Unit Capacity Research Articles

Development, Implementation, and Impact of a Proning Team During the COVID-19 Intensive Care Unit Surge.

Prone positioning has been used as an intervention to improve oxygenation in critically ill patients with acute respiratory distress syndrome. During the COVID-19 pandemic, resources were even more limited given a surge in acute respiratory distress syndrome patients, which outstripped intensive care unit (ICU) capacity at many institutions. The purpose of this article is to describe the development and implementation of a proning team during the surge in ICU patients with COVID-19 and to measure the impact of the program through surveys of staff involved. A proning protocol and educational plan was developed. A proning team of redeployed staff was created. A survey of ICU registered nurses and proning team members was used to evaluate the benefits and challenges of the proning team. The proning team was successful in safely performing more than 300 proning and supinating maneuvers for critically ill patients. There is overwhelming support within the institution for a proning team for future COVID-19 surges. The development and implementation of the proning team happened quickly to assist with the surge of patients and off-load work from ICU registered nurses. Despite the success of the proning team, more clearly defined roles and expectations, as well as additional education, are needed to further enhance teamwork and workflow. Creation of the proning team was a creative use of resources that helped manage the large and medically complex patient population. This work may serve as a guide to other health care institutions.

Development and Approbation of Methodology Aimed to Define the Reasons for Turbine Unit Capacity Limitation Based on the Specified Mathematical Model of its Condenser

The purpose of this work is to develop and test the methodology of elucidation of the reasons for turbine unit capacity limitations based on a mathematical model of its condenser. This pur-pose is achieved by using a mathematical model of the condenser as part of the developed methodology, taking into account the separate effects of contamination of the heat exchange surfaces, air suction into the vacuum system and the operating mode of the main ejector. Based on operational data sampling, the value of the limiting pressure in the condenser, excess of which leads to limitation of turbine unit capacity, was determined. It was established that the cause of power limitation is the abnormal operation of the main ejector due to inadmissible high temperature in the intermediate cooler of its first stage. For regimes that were not pressure-limited, using a mathematical model, the degree of tubes contamination, its influence on the condenser pressure and the power generated by the turbine unit, and the influence of actual air suctions on the condenser pressure were determined. The most important result of the study is to determine the possibility and feasibility of using the developed and tested methodology for solv-ing similar problems for any type of turbine unit equipped with a condenser. The significance of the work lies in the fact that the proposed approach expands the possibilities of using mathemat-ical models of this class in terms of solving such problems.

Determination of the Average Specific Capital Consumptions of CCPP with Gas Turbine of 30-125 MW and Put into Operation at TPPs of the Russian Federation from 2015 to the First Quarter of 2021

Research was carried out on the volume of gas turbine commissioning in the range of unit capacities of 30–125 MW at TPPs of the Russian Federation operating as part of a CCPP in the period from 2015 to the first quarter of 2021. The purpose of the research was to determine the average specific capital investment in construction and the average specific fuel consumption for the supply of electricity and heat for the CCPP introduced over the years in the united energy systems of the Russian Federation. Gas turbines are classified by electrical capacity into three groups: from 100 to 125 MW, from 60 to 99 MW and from 30 to 59 MW. An assessment of the quantitative distribution of gas turbines over the interconnected energy systems of the Russian Federation has been carried out. The results of the comparison of the quantitative commissioning of gas turbines are shown in the period from 2010 to the economic crisis of 2014 and in the period from 2015 to the present. A preliminary estimate of the increase in average specific capital investments in the construction of CCPP, which included gas turbines of the same electric power, was made for these periods.

Comparative Efficiency Evaluation of Hydrogen Energy Complexes Based on Reversible Fuel Cells and Hydrogen-Thermal Storage When Combined with Nuclear Power Plants

This work evaluates the technical and economic efficiency of combining NPPs with a system based on reversible fuel cells (RFC) in comparison with the well-known approach of hydrogen-thermal accumulation (HTA) using an additional low-power steam turbine unit. One of the main advantages of RFC is its ability to alternately operate both in the electrolysis mode in order to accumulate off-peak electricity, and in the fuel cell mode to generate peak electricity without converting hydrogen fuel energy into thermal or mechanical energy. The authors developed a schematic diagram and methodology for assessing efficiency of using RFC at NPPs. The calculations have shown that at the present stage of technology development, the use of RFC is less effective in comparison with the system based on HTA. At the same time, until 2035the advantage of the HTA will grow from 9.68%, excluding the economic effect from preventing unloading of the NPP, up to 25.31% in the current scenario, taking into account the economic effect from preventing unloading of the NPP. The target level of base specific capital investments in the proposed RFC system (units with a unit capacity of 250 kW) has been determined, providing equal technical and economic efficiency in comparison with HTA, which amounted to 1079-1134 $/kW

Doubling Intensive Care Unit Capacity by Surging Onto Medical-Surgical Units During the COVID-19 Pandemic.

The ability of an organization to accommodate a large influx of patients during a prolonged period is dependent on surge capacity. The aim of this article is to describe the surge experience with space, supplies, and staff training in response to COVID-19 and provide guidance to other organizations. A hospital's response to a large-scale event is greatly impacted by the ability to surge and, depending on the type of threat, to maintain a sustained response. To identify surge capacity, an organization must first consider the type of event to appropriately plan resources. An epidemic surge drill, conducted in 2012, served as a guide in planning for the COVID-19 pandemic. The principles of crisis standards of care and a hospital incident command structure were used to clearly define roles, open lines of communication, and inform our surge plan. Preparation began by collaborating with multidisciplinary groups to acquire the most appropriate space, as well as adequate supplies, and identify and train staff. Teams were formed to identify the necessary resources to expand the intensive care unit (ICU) environment quickly and efficiently. Educational training was developed for redeployed staff. Beth Israel Deaconess Medical Center experienced the largest surge of ICU patients within a hospital system in the state of Massachusetts. The ICU capacity was expanded by 93% from 77 to 149 beds, and the surge was maintained for approximately 9 weeks. Shadowing experiences before the actual surge were extremely valuable. Planning for the surge of critically ill patients required a thoughtful, collaborative approach. Ongoing staff support and communication from nursing leadership were necessary to ensure safe, effective care for critically ill patients in a new and dynamic environment.

Techno-Commercial Study of a Solar Hybrid Renewable Energy Generator With an Initial Sizing Strategy

Abstract Solar energy-based hybrid renewable energy generators are techno-economically designed for various standalone uses such as far-distance area electrification, commerical building electrification, polygeneration, and industrial application. This article attempts to address the problem of high cost of energy of such generators, which needs to be optimized. The research gap is that there is hardly any work on techno-economic optimization of such generators using an initial sizing technique, thereby resulting in a design with higher cost of energy. In this work, a hybrid renewable energy generator comprising solar photovoltaic-biogas-battery storage is techno-economically optimized with the aim of minimizing its cost of energy for electrification of a radio-broadcasting station in India by using simulation software called hybrid optimization model for electric renewables. An initial sizing strategy has been proposed in the modeling of the hybrid system. Optimal designs are obtained under different scenarios like in the standalone mode with and without capacity shortage fraction and in grid-connected mode with scheduled and random outages. The results show that during initial sizing in the standalone mode, consideration of larger size (25 kW) of the component with lower unit capacity cost (biogas unit) and higher load sharing by it (102,625 kWh/year) in the energy management of the hybrid design with a small capacity shortage (5%) reduces the levelized cost of energy to 0.0956 $/kWh compared to some of the literature designs. Of all the optimal designs, the grid-connected system has the lowest levelized cost of energy of 0.0873 $/kWh with a renewable fraction of 0.821. The present work contributes to the component size planning of hybrid renewable energy generator to generate lower levelized cost of energy. The novelty of the present work is that in the component size planning in the standalone mode, following the initial sizing strategy, if the component with lower unit capacity cost shares majority of the load, then the levelized cost of energy with or without grid-connected mode can be further reduced compared to some existing designs, which can be verified from the simulation results. Therefore, the present results will be useful for component planning and sizing of hybrid renewable generators so as to preset the size of its components as per their unit capacity cost to result in a lower cost of energy.

Hydroxyapatite-hybridized double-network hydrogel surface enhances differentiation of bone marrow-derived mesenchymal stem cells to osteogenic cells.

Recently, we have developed a hydroxyapatite (HAp)-hybridized double-network (DN) hydrogel (HAp/DN gel), which can robustly bond to the bone tissue in the living body. The purpose of this study is to clarify whether the HAp/DN gel surface can differentiate the bone marrow-derived mesenchymal stem cells (MSCs) to osteogenic cells. We used the MSCs which were harvested from the rabbit bone marrow and cultured on the polystyrene (PS) dish using the autogenous serum-supplemented medium. First, we confirmed the properties of MSCs by evaluating colony forming unit capacity, expression of MSC markers using flow cytometry, and multidifferential capacity. Secondly, polymerase chain reaction analysis demonstrated that the HAp/DN gel surface significantly enhanced mRNA expression of the eight osteogenic markers (TGF-β1, BMP-2, Runx2, Col-1, ALP, OPN, BSP, and OCN) in the cultured MSCs at 7 days than the PS surfaces (p < 0.0001), while the DN gel and HAp surfaces provided no or only a slight effect on the expression of these markers except for Runx2. Additionally, the alkaline phosphatase activity was significantly higher in the cells cultured on the HAp/DN gel surface than in the other three material surfaces (p < 0.0001). Thirdly, when the HAp/DN gel plug was implanted into the rabbit bone marrow, MSC marker-positive cells were recruited in the tissue generated around the plug at 3 days, and Runx2 and OCN were highly expressed in these cells. In conclusion, this study demonstrated that the HAp/DN gel surface can differentiate the MSCs into osteogenic cells.

Determination of granule (prill) movement modes in the prilling tower for mineral fertilizer production

The object of research is the mode of movement of the granules of mineral fertilizers obtained in the towers. The subject of research is the effect of the physical and chemical properties of granules, their size and initial hydrodynamic parameters on the speed of movement of the granules in the tower. The fertilizer industry is characterized by high requirements for the production of mineral fertilizers, which makes it promising to use granulation plants of large unit capacity, tower production. The resulting product must have a stable physical and chemical composition, be monodisperse with a spherical shape of granules, which allows long-term storage in bulk without the use of auxiliary equipment and meet international quality standards. The main granulation equipment that is used in the tower production of mineral fertilizers is spray type granulation equipment. In such towers, there is a likelihood of crossing pellet flares, getting pellets into the walls of the pelletizing tower and adhesion of the melt on this surface in industrial conditions, which leads to negative consequences. Therefore, the determination of the modes of motion of granules is still important. Methods of mathematical modeling of the movement of granules under different conditions were used in the work. Numerical methods were used to solve the equations of differential equations. As a result, an equation was obtained to determine the speed components along the x and y axes. The calculation of the horizontal speed of the granule and the determination of the time of its movement in the working area of the prilling tower makes it possible to determine the length of the granule path in this direction, to determine the diameter of the spray torch of the granules. Provides information on preventing the ingress of granules into the walls of the prilling tower and adhesion of the melt on this surface in industrial conditions, which leads to negative consequences. The magnitude of the speed, especially for the vertical component, changes its value several times over time due to a change in the mode of motion of the granules when moving from the granulator down the tower. This indicates the need to also take into account the change in the value of the resistance coefficient over time. When deriving the equations, simplifications were used, and the motion of a solid granule was considered. However, a drop begins to move from the granulator (disperser), which then crystallizes into a granule. Comparing the obtained results, allowing to predict by calculation the behavior of the spray plume of granules, with the initial ones obtained in industrial conditions, it is possible to conclude that the error of the equations obtained is 10.5%. Therefore, work on improving the obtained equations describing the mode of motion (speed) of the granules will be continued.

Early health system responses to the COVID-19 pandemic in Mediterranean countries: A tale of successes and challenges

This paper conducts a comparative review of the (curative) health systems’ response taken by Cyprus, Greece, Israel, Italy, Malta, Portugal, and Spain during the first six months of the COVID-19 pandemic. Prior to the COVID-19 pandemic, these Mediterranean countries shared similarities in terms of health system resources, which were low compared to the EU/OECD average. We distill key policy insights regarding the governance tools adopted to manage the pandemic, the means to secure sufficient physical infrastructure and workforce capacity and some financing and coverage aspects.We performed a qualitative analysis of the evidence reported to the ‘Health System Response Monitor’ platform of the European Observatory by country experts. We found that governance in the early stages of the pandemic was undertaken centrally in all the Mediterranean countries, even in Italy and Spain where regional authorities usually have autonomy over health matters. Stretched public resources prompted countries to deploy “flexible” intensive care unit capacity and health workforce resources as agile solutions. The private sector was also utilized to expand resources and health workforce capacity, through special public-private partnerships. Countries ensured universal coverage for COVID-19-related services, even for groups not usually entitled to free publicly financed health care, such as undocumented migrants.We conclude that flexibility, speed and adaptive management in health policy responses were key to responding to immediate needs during the COVID-19 pandemic. Financial barriers to accessing care as well as potentially higher mortality rates were avoided in most of the countries during the first wave. Yet it is still early to assess to what extent countries were able to maintain essential services without undermining equitable access to high quality care.

Study on heat transfer characteristics of regenerative shell-and-tube heat exchangers

A new type of regenerative shell-and-tube heat exchanger is designed to solve the problems that the generation load of cogeneration units is limited by the amount of heat supply during the heating period, the peak shaving capacity of units decreases, and the phenomenon of wind and light abandonment in the power system is serious. Considering the advantages of nearly constant temperature and large potential heat release during the heat storage/release process ofphase change materials, paraffin is selected as the phase change material, and the phase change area of the heat exchanger is selected as the heat exchange unit. The control variates method is used to simulate the heat storage/release process of the heat exchange unit according to the key factors such as the flow rate of heat transfer fluid, the thermal conductivity of phase change materials and the thickness of phase change layer. The results show that increasing the flow rate of heat transfer fluid can enhance the heat storage capacity of the heat exchange unit and shorten the complete melting time of phase change materials. In order to control the heat at the output end of the heat exchanger during the heat release process, the flow rate of heat transfer fluid should be appropriately selected; using composite materials to improve the thermal conductivity of phase change materials can enhance the heat transfer capacity of the heat exchange unit, and the average heat transfer coefficient of the heat exchange unit is more than 2 times higher than that of pure paraffin at the same heat transfer fluid flow rate; increasing the thickness of phase change layer can prolong the time of maintaining the outlet temperature of heat transfer fluid in the process of heat release.

Validation of inertial measurement units for the assessment of trunk control in subjects with spinal cord injury

Background: Trunk control (TC) constitutes one of the main objectives in the rehabilitation of people with a spinal cord injury (SCI), but there are few clinically validated tests to assess it. Accelerometers have been proposed as sensitive and suitable procedures to assess TC. Objective: To evaluate test–retest reliability, construct and criterion validity of accelerometer parameters to assess TC in people with SCI. Methods: A cross-sectional study of simultaneous application of Clinical Trunk Control Test (CTCT) and accelerometer evaluation was conducted. Accelerometers were placed on the trunks of 27 people with SCI and 15 people without SCI. Reliability was assessed by three repeated measures in random order of selected static and dynamic TC tasks. Acceleration on three axes was analyzed using five metrics. Criterion validity was assessed by analyzing correlation of acceleration to CTCT scores. Construct validity was assessed by analyzing capacity of inertial measurement units (IMU) to differentiate individual’s characteristics, ASIA Impairment scale, gait capacity, level of TC, and neurological level of injury. Results: Reliable IMU data were obtained in people with SCI and without SCI, of all accelerometer axes, metrics, and tested items of the CTCT. Reliability of acceleration decreases with the increasing demand for TC tasks. Ten acceleration parameters showed construct and criterion validity. Conclusion: Accelerometer parameters are reliable, valid, and sensitive to evaluate TC in people with SCI. Significance: A set of IMU parameters were validated as reliable and valid measures to evaluate TC, which could be useful for the assessment of progression of people with SCI and clinical interventions.

Safety and feasibility of a nurse-led ambulatory abdominal paracentesis service.

63 Background: Ascites is a common complication of cancer. Symptomatic ascites contributes to cancer-related morbidity and is distressing for patients (pts). Therapeutic abdominal paracentesis (TAP) provides symptom relief but requires specialized procedural knowledge and is usually performed in the inpatient setting with several days of hospitalization. Additionally, high hospital bed occupancy during the COVID-19 pandemic prevented timely admission for TAP. An Advanced Practice Nurse (APN)-led ambulatory TAP service was introduced at our center, with the aim of improving access to TAP and reducing hospital bed occupancy. Methods: A multidisciplinary team developed workflows and safety guidelines for TAP to enable right-siting of pts in a cancer day care unit. Pts were scheduled for radiologically guided insertion of abdominal drains in the morning before 10am to allow adequate time for drainage. Pre-procedure clinical examination and safety checks were performed by APNs in the day unit. Following the procedure, abdominal fluid was drained with concurrent administration of 20% IV albumin. Drains were removed by the APN and pts were examined before discharge on the same day. Data for all cancer pts requiring TAP in the day unit and hospital from 1 Jan to 30 Nov 2020 were extracted from the electronic medical record system. The primary outcome was length-of-stay (LOS). The primary safety outcome was adverse events in the day unit. Continuous data were compared using the t-test. Data analysis was done in SPSS version 22. Results: The number of TAPs performed in the day unit and general ward requiring hospitalization were 102 and 133, respectively. There was a significant reduction in average LOS with TAPs performed in the day unit vs. hospitalization (1.48 vs. 5.82 days, p&lt;0.001) (Table). The mean difference was 4.34 (95% confidence interval 3.33 - 5.34) days saved per pt, or a saving of 443 inpatient bed days. The TAP day unit service encountered 10 adverse events (AEs) requiring admission to the ward for continued drainage. AEs were borderline baseline blood pressure, pt frailty and inability to care for an indwelling catheter. There were no infective or bleeding complications. The majority of TAPs (86.8%) were performed in one day, with the remainder over 2-days with the abdominal drain left in-situ and reattendance at the day unit the next day for further drainage. Differences in average length-of-stay with TAP in the hospital vs. day unit. Conclusions: An APN-led ambulatory abdominal paracentesis service is a safe alternative to inpatient paracentesis. Optimal utilization of a day unit enabled reduced LOS for pts with advanced cancer. This reduction in LOS was critical during a pandemic where bed demand was high. This was possible from advanced scheduling and control over the day unit capacity.[Table: see text]

Stress and burnout among health-care workers in the coronavirus disease 2019 intensive care unit.

Since late December 2019, the city of Wuhan in China has reported a novel pneumonia caused by coronavirus disease 2019 (COVID-19), which has now spread domestically and internationally. The COVID-19 pandemic has caused unthinkable consequences and has challenged and, in numerous cases, beaten the capacity of hospitals and intensive care units (ICUs) worldwide to handle it. Apart from the obvious burden of patient care, extended work timings, and fear of personal safety, health-care workers (HCWs) also suffer from occupational stress as a result of lack of skills, organizational factors, and low social support at work leading to distress, burnout, and psychosomatic problems. This leads to stress, direct deterioration in quality of life as well as the quality of service provided. In this article, the authors navigate on the root cause of stress that is peculiar to the HCWs deployed in the ICU and suggest recommendations to alleviate it. To aid in the research, we searched the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, PsycINFO, CINAHL, NIOSHTIC-2, and Web of Science up to May 2021.

Development of an indoor air purification system to improve ventilation and air quality

Novel types of an air purification system for improving indoor air quality (IAQ) and ventilation by reducing carbon dioxide (CO2) concentration were assessed in office buildings in India. This study provides an evaluation of a control system that reduces toxic gases in indoor spaces using the synthesized filter media. The reduction potential of CO2 levels of the control system, for different air handling unit (AHU) capacities, were compared. Experimental studies and in-situ evaluation has been done using the air purification system. Ventilation rates and CO2 concentration are monitored before and after the installation of the purification system. The results of the investigation indicated CO2 concentrations were reduced by more than 40% with the purification system. Fresh air intake to maintain the desired ventilation rates has been reduced to more than 50%, further reduce heat load. Ventilation flow rates were achieved with this air purification system. This system has the potential aspiration in controlling the CO2 levels in mechanically ventilated buildings. CO2 concentrations were brought down to permissible limits and maintained further without introducing fresh air into the system. Based on the results, assessment of the air purification system is a crucial and wide range of applicability in indoor environments to reduce cooling costs.

Assessing the Risk to Indoor Thermal Environments on Industrial Sites Offering AHU Capacity for Demand Response

Increasing participation in demand response within the industrial sector may be crucial to growing the levels of available flexible capacity required to reliably control national electricity grids as renewable generation increases to satisfy emission targets. This research aims to assist the uptake of demand response in the industrial sector by investigating risk to indoor thermal environments on industrial sites offering air handling unit capacity for demand response. This evaluation uses a systematic model-based approach, calibrated and validated with empirical data from a relevant case study industrial building to assess risk through a number of scenarios. The conditions investigated cover several relevant grid response times and durations, and national and international extreme external ambient temperatures in the past, present and future under a variety of temperature limits. The study demonstrated that there is very low risk to the case study site participating in demand response, with only 15 of 264 initial and 284 of 936 total scenarios triggering any risk. The major factors affecting risk levels identified were more stringent temperature limits and the influence of more extreme climates. The development and implementation of this concept has considerable potential to benefit industrial participants and the wider national electricity grids.

Техніко-економічні показники технологій теплової енергетики, що експлуатуються в маневрених режимах

There is a deficit in united energy system of Ukraine of installed capacity of flexible generation units which are able to quickly reach the operating mode, change the power generation levels in a wide range. To model additional measures increasing the flexibility of the power system, it is necessary to know the technical and economic indicators of thermal power technologies and its specific operating modes. The purpose of the article is to determine: efficiency factors depending on the power unit load; start-up costs depending on downtime duration and different fuel prices; the influence of maneuvering modes on lifetime resource indicators; as well as comparison of indicators for various technologies of thermal energy. The following thermal power technologies: natural gas, hard or bituminous coal fired steam turbine supercritical pressure, steam-gas, gas turbine open cycle and gas piston engines. The calculation formulas allowing estimate the influence of the power plant operation mode on the efficiency is obtained. The results of calculation of the start-up specific costs depending from the type of the unit and the idle time is presented. The different values of thermal power unit start-up cost are presented depending on idle time. As an example, the balancing of 660 MW electric power with different equipment composition are considered. The analysis of the results shows that the highest start-up cost is for coal-fired steam turbine plants, and the composition of the equipment with the lowest start-up cost varies depending on the downtime: up to 2 hours, 2 – 5 hours, more than 5 hours. Formulas for recalculating the cost of starting at different fuel prices are obtained. The influence of maneuvering modes on the lifetime resource indicators of thermal power plants is also presented. The conventional thermal power generators of the united energy system of Ukraine have actually overcome their physical capabilities to ensure effective load following, therefore, it is necessary to introduce new highly flexible capacities, and the proposed formulas and results could be helpful to determine the volumes and characteristics of new thermal power plants needed to implement into power system. Keywords: thermal power, maneuverable mode, efficiency, downtime, start-up cost, service life

Economic solution for low carbon process heat: A horizontal, compact high temperature gas reactor

In 2018, nuclear energy generated 55% of United States’ and one third of the world’s carbon free electricity, making nuclear energy a key tool in efforts to mitigate climate change before 2050. However, the current nuclear technology, light water reactors (LWRs), is limited to 300°C, so it cannot be used to decarbonize industrial process heat which accounts for 12% of US greenhouse gas emissions. High temperature gas reactors (HTGRs) can meet the high temperature demand with carbon free nuclear heat. The estimated cost of HTGRs, such as the Next Generation Nuclear Plant (NGNP), are even higher than state-of-the-art LWRs. In this paper, we expanded our nuclear cost estimating tool to include HTGRs and find that the NGNP overnight capital costs were 32% higher than an advanced LWR per unit capacity. The higher cost will naturally result in larger risk to cost overrun as recently experienced by larger LWRs in western nations. With a design-to-build mindset to minimize cost and construction risk, we introduce the horizontal, compact HTGR (HC-HTGR). The reactor core and steam generator are mounted horizontally on rails and in-line with one another, decreasing the size of the reactor building relative to the power capacity four times when compared to traditional HTGRs. The HC-HTGR reduced overnight civil structure costs by 42%, indirect costs by 38%, and total capital costs by 20% from NGNP. We discussed the required engineering of new systems for the HC-HTGR including vessel supports, the reactor cavity cooling system, and steam generator design. Finally, we estimated the fuel and operations costs of the HC-HTGR, and a survey of low-carbon industrial process heat technology showed the HC-HTGR can deliver a highly competitive levelized cost of heat in the range of $6.13–12.48/GJ.

Analysis of the influence of the current-voltage characteristics of the voltage rectifiers on the static characteristics of hydrogen electrolyzer load

Traditionally, the determination of static load characteristics is one of the main stages in the preparation of a design model of an electric power system. It is especially important to correctly take into account energy-intensive industries, which make a huge contribution to the formation of these characteristics. In particular, the increased interest in hydrogen technologies observed in the world as one of the most promising high-tech areas of energy development, and an increase in the share of the installed capacity of generation units based on renewable energy sources determine the prospects for the development of hydrogen production by water electrolysis. Accordingly, a significant increase in the scale of application of hydrogen technologies, in particular, in accordance with the “Hydrogen Strategy for Climatically Neutral Europe”, the European Commission for the production of “green” hydrogen, determines the task of forming correct mathematical models of these devices in terms planning of modes, analyzing their impact on the parameters of electric power systems. Determination of static load characteristics on the basis of a physical experiment will not allow obtaining a characteristic with a significant increase or decrease in voltage in the node of the electric power system, which occur only in emergency modes of operation of the power system. Therefore, it seems relevant to analyze and determine the electrical characteristics of consumers by mathematical modeling of the power circuit. This article presents the results of correcting the static load characteristic of a high-power electrolyzer used in the production of hydrogen. The analysis of these results obtained with the MATLAB software is carried out using least squares regression to procure polynomial functions of the static load characteristics. According to this analysis, the static characteristics of the considered electrolyzer, being close to linear within the control range, outside the control range acquire parabolic dependences of active and reactive power on voltage. The static load characteristics of the installation are determined by the parameters of the power circuit and the current-voltage characteristic of the rectifiers displacing the vertices of the parabolas from the origin, which should be taken into account to increase the reliability of the design scheme.

Optimal Reopening Pathways With COVID-19 Vaccine Rollout and Emerging Variants of Concern.

We developed a stochastic optimization technology based on a COVID-19 transmission dynamics model to determine optimal pathways from lockdown toward reopening with different scales and speeds of mass vaccine rollout in order to maximize social economical activities while not overwhelming the health system capacity in general, hospitalization beds, and intensive care units in particular. We used the Province of Ontario, Canada as a case study to demonstrate the methodology and the optimal decision trees; but our method and algorithm are generic and can be adapted to other settings. Our model framework and optimization strategies take into account the likely range of social contacts during different phases of a gradual reopening process and consider the uncertainties of these contact rates due to variations of individual behaviors and compliance. The results show that, without a mass vaccination rollout, there would be multiple optimal pathways should this strategy be adopted right after the Province's lockdown and stay-at-home order; however, once reopening has started earlier than the timing determined in the optimal pathway, an optimal pathway with similar constraints no longer exists, and sub-optimal pathways with increased demand for intensive care units can be found, but the choice is limited and the pathway is narrow. We also simulated the situation when the reopening starts after the mass vaccination has been rolled out, and we concluded that optimal pathways toward near pre-pandemic activity level is feasible given an accelerated vaccination rollout plan, with the final activity level being determined by the vaccine coverage and the transmissibility of the dominating strain.

Colorectal cancer screening: foreign guidelines on fecal immunochemical test cut-off (review)

Introduction. According to WHO data for 2020, colorectal cancer occupies first (highest) position (excluding non-melanoma skin cancer) in the top ranking list of the most frequent cancers in the Russian Federation. Colorectal cancer screening plays a pivotal role in early diagnosis and treatment. The best positive threshold values for hemoglobin concentration in a quantitative fecal immunochemical test (FIT) are postulated in a fraction of foreign recommendations. We reviewed the FIT cut-off values in those clinical guidelines. Materials and methods. The relevant publications were retrieved from PubMed and Google. The search horizon covered the last decade. Searches used the terms: «fecal immunochemical test» AND «screening» OR «cancer» AND «colorectal» OR «colon» OR «rectum", as well as other semantic and thematic forms. The recommendations appeared in last decade were reviewed. Results. This review summarizes the cut-off values for hemoglobin concentration in FIT, included in the clinical and laboratory guidelines developed in such regions as: Europe, Canada, USA, New Zealand. Many CRC screening programs use the FIT with a threshold setting for interpreting a positive test result. In practice, a wide range of options for threshold hemoglobin concentrations is used to interpret positive results of quantitative FIT. The FIT cut-off value is critically important to select the size of population for further examination depending on capacity of colonoscopy units. Discussion and conclusions. The foreign guidelines don’t establish single unified approach for FIT results interpretation, which would be an optimal fit for all imaginable practical situations in healthcare system. Improvement of screening techniques based on FIT would lead to the further steps on the way towards more effective and safe CRC diagnosis.