Volume Flow Research Articles

Exposure to nitrate and nitrite disrupts cardiovascular development through estrogen receptor in zebrafish embryos and larvae.

Increasing nitrate concentration on surface and groundwater due to anthropogenic activities is an environmental concern. In this study, Tg(fli1: EGFP) zebrafish embryos were exposed to nitrate (NO3-) and nitrite (NO2-), and their cardiovascular development were investigated. Exposure to 10mg/L NO3-N and 1 and 10mg/L NO2-N decreased heart rate at 48-96-h post-fertilization (hpf), ventricular volume, and red blood cell flow rate at 96 hpf. Similar concentrations increased the number of embryos and larvae with pericardial edema and missing intersegmental and parachordal vessels in the caudal region at 48-96 hpf. Addition of ICI 182,720 (ICI) reversed the effects of nitrate and nitrite, suggesting estrogen receptors (ER) are involved. 10mg/L NO3-N and 1mg/L NO2-N decreased cardiovascular-related genes, gata4,5,6, hand2, nkx2.5, nkx2.7, tbx2a, tbx2b, and fgf1a. Gene expressions of ovarian aromatase and brain aromatase (cyp19a1a and cyp19a1b, respectively) decreased in the exposed groups, whereas ERs (esr1, esr2a, and esr2b) and nitric oxide synthase 2a (nos2a) increased. The effects on gene expression were also reversed by addition of ICI. Taken together, nitrate and nitrite disrupt cardiovascular system through ER in developing zebrafish, implying that environmental nitrate and nitrite contamination may be harmful to aquatic organisms.

Assessment of endometrial and subendometrial three-dimensional power Doppler angiography evaluated by the VOCAL method in frozen-thawed embryo transfer cycles on hormone replacement therapy

BACKGROUND: The effectiveness of in vitro fertilization cycles / frozen-thawed embryo transfer cycles depends on a number of factors, the endometrial one being of great importance. Adequate endometrial and subendometrial blood supply is considered necessary for successful implantation. Currently, the possibilities of non-invasive assessment of the implantation properties of the endometrium are limited to the use of ultrasound. AIM: The aim of this study was to assess the performance of endometrial and subendometrial three-dimensional power Doppler angiography combined with the Virtual Organ Computer-aided Analysis (VOCAL) method in frozen-thawed embryo transfer cycles on hormone replacement therapy and compare the obtained data among the women examined. MATERIALS AND METHODS: This prospective study included 20 women. Doppler measurements were carried out three times — on the day of progesterone initiation, the day before embryo transfer and on the day of embryo transfer. The VOCAL software assessed the endometrial and subendometrial volume and blood flow indices such as vascularization index, flow index, and vascularization flow index. Patients were divided into two study groups depending on the onset of clinical pregnancy. RESULTS: On the day of progesterone initiation among patients who got pregnant, we observed higher vascularization (3.52 ± 1.99 vs. 1.05 ± 1.36; p = 0.03) and vascularization flow (1.54 ± 0.98 vs. 0.63 ± 0.55; p = 0.03) indices compared to women with a negative result. Moreover, endometrial vascularization index on the day of progesterone initiation was positively correlated with the estrogen dose among both pregnant (r = 0.61; p = 0.04) and non-pregnant (r = 0.9; p = 0.0008) women. No differences in subendometrial blood flow indices depending on the onset of pregnancy were obtained, just as endometrial blood flow indices the day before embryo transfer and on the day of embryo transfer were comparable between women in the both study groups. CONCLUSIONS: Three-dimensional power Doppler angiography evaluated by the Virtual Organ Computer-aided Analysis (VOCAL) method is a promising tool for non-invasive assessment of endometrial receptivity in frozen-thawed embryo transfer programs. However, further studies are required on a larger patient sample to form conclusions that are more accurate.

The role of umbilical-portal venous hemodynamics in fetal macrosomia pathogenesis in pregnancy complicated by diabetes mellitus

BACKGROUND: During pregnancy complicated by diabetes mellitus, the risks of developing fetal macrosomia and other perinatal complications increase. Redistribution of blood flow in the fetal umbilical-portal venous system may be an important but poorly understood compensatory mechanism that affects macrosomic fetal growth. AIM: The aim of this study was to determine the features of the fetal umbilical-portal venous hemodynamics in pregnant women with various types of diabetes mellitus and the absence of carbohydrate metabolism disorders, taking into account the gestational age and the macrosomic fetal growth. MATERIALS AND METHODS: In this prospective cohort study, 86 pregnant women with pregestational diabetes mellitus, 44 pregnant women with gestational diabetes mellitus and 58 patients without carbohydrate metabolism disorders underwent ultrasound examinations from 30+0 to 41+3 weeks of gestation. During ultrasound, we performed Doppler assessment of venous hemodynamic parameters in the vessels of the umbilical-portal venous system, with volumetric blood flow calculated for each vessel. Additionally, the total liver volumetric blood flow and ductus venosus shunt fraction were calculated. RESULTS: The presence of fetal macrosomia in patients from the pregestational diabetes mellitus group is associated with an increase in the volumetric blood flow of the umbilical vein by 89.5 ml/min (p = 0.003) and the left portal vein by 33.3 ml/min (p = 0.008), as well as the total volumetric blood flow of the fetal liver by 95.7 ml/min (p = 0.001) compared with normal-weight fetuses. At the same time, the ductus venosus shunt fraction decreased in macrosomic fetuses by 3.83% (p = 0.001). In the gestational diabetes mellitus and control groups, despite the tendency for these parameters to increase in fetuses with macrosomia, the differences did not reach statistical significance. With a left portal vein volume flow threshold of 94.51 ml/min, the sensitivity and specificity for predicting large births were 84.46 and 72.09%, respectively. CONCLUSIONS: Pregestational diabetes mellitus in the mother is associated with a priority redistribution of blood flow to the fetal liver and is accompanied by a decrease in the ductus venosus shunt fraction. The severity of these hemodynamic changes increases in the presence of fetal macrosomia, which confirms the role of liver perfusion in the regulation of fetal growth in uncomplicated pregnancy and maternal diabetes mellitus.

Technical Aspects of Natural Gas Pyrolysis in Liquid Metal Bubble Column Reactors

The pyrolysis of low alkanes (in the following short “pyrolysis”) has already been investigated during the 1960s. However, none of the reactor systems used at the time are capable of continuous operation. Therefore, the Karlsruhe Institute of Technology has intensified the development of the promising liquid metal bubble column technology in recent years, which is capable of continuous operation. Various key aspects have been addressed, such as scale‐up and the pyrolysis of high‐caloric natural gas. Herein, further developments for a pilot scale system have been investigated, which concern increased throughput and long‐term operation capabilities. Careful evaluation of the impact of according measures has been done, which shows that the achieved scale‐up has only negligible effects on the pyrolysis outcome. The effects of the scale‐up on residence times are negligible. The bubble formation behavior depends on the throughput and the characteristics of the orifice. Wall effects are marginal. Fundamental minimization of weeping could not be confirmed. Reactor pre‐chambers in combination with tin collection chambers are recommended for further scale‐up. An increase in the volume flow should be examined. In terms of long‐term operation , head as well as feed pressure control is recommended.

Determination of the impacts of supplemental dietary curcumin on post-partum uterine involution using pulsed-wave doppler ultrasonography in Zaraibi goat

This study aimed to evaluate the impacts of supplemental dietary curcumin on post-partum uterine involution using pulsed-wave Doppler ultrasonography in postpartum goats. Ten pluriparous Zaraibi goats were used and divided into two groups. Group 1 (n = 5; control) received only a base diet. Group 2 (n = 5; treated) received a base diet supplemented with curcumin (200 mg/kg diet) daily for 28 days, starting from day 1 postpartum (PP) till day 28 PP. Uterine morphometrical changes (uterine horn diameter; UHD and caruncle diameter; CD), uterine hemodynamics (resistance and pulsatility indices (RI and PI), systolic/ diastolic ratio (S/D), peak systolic velocity (PSV), end-diastolic velocity (EDV), blood flow volume (BFV), and blood flow rate (BFR)), and progesterone level were evaluated. Results revealed that the diameter of the uterine horn decreased rapidly from day 1 to day 10 PP (> 50%) but more steadily from day 14 to day 28 PP in both groups. After day 21 PP, there was nearly no reduction in UHD and CD in both groups. The treated group had lower values of the RI and PI (P < 0.05) than the control group. Regarding the BFR and BFV in the treated group, there was a significant increase (P < 0.05) on day 17 PP, then started to decrease till day 28 PP. While in the control group, there was a significant decrease (P < 0.05) in BFR and BFV from day 1 PP till day 28 PP. In conclusion, the incorporation of curcumin in the diet of PP Zaraibi goats improved reproductive performance via improvements in uterine morphometric changes as well as blood perfusion.

Value of foetal umbilical vein standardised blood flow volume in predicting weight gain in the third trimester: a prospective case-cohort study

ObjectiveThis study aims to establish a prediction model of foetal umbilical vein standardised blood flow volume (sQuv) on estimated foetal weight (EFW) in the third trimester.MethodsA case-cohort study involving 200 eligible normal foetuses was conducted at the Ultrasound Department of Longquanyi District of Maternity and Child Healthcare Hospital between June 1, 2020 and December 31, 2021. Ultrasound measurements were taken at two separate intervals to assess EFW and the rate of EFW (rEFW) [first: between 28 w and 33 w6d of gestational age (GA); second: after 4–6 weeks]. Umbilical vein blood flow volume (Quv) and sQuv (normalised with EFW) were calculated only during the initial measurement. Using general linear regression, a prediction model for EFW based on GA and sQuv was developed, with the gestational week employed as a calibration scalar and validated using linear regression cross-validation.ResultsIn the third trimester, EFW exhibited significant correlations with GA, abdominal circumference (AC), head circumference (HC) and Quv (all ρ &amp;gt; 0.6, P &amp;lt; 0.001). Furthermore, the rEFW showed significant correlations with Quv and sQuv (all ρ &amp;gt; 0.6, P &amp;lt; 0.001). A linear regression equation was established using a general linear regression model: rEFW = 0.32689 × sQuv. Additionally, a foetal weight prediction model (EFW = −2,554.6770 + 0.9655 × sQuv + 129.6916 × GA) was established using sQuv. The above two formulas were cross-validated by intra-group linear regression and proved to be of good efficacy.ConclusionsIn the third trimester, EFW displayed significant correlations with GA, AC, HC and Quv. Additionally, the rEFW exhibited significant correlations with Quv and sQuv. The sQuv during the third trimester has predictive value for foetal weight, serving as an early warning indicator.

Probabilistic assessment of postfire debris-flow inundation in response to forecast rainfall

Abstract. Communities downstream of burned steep lands face increases in debris-flow hazards due to fire effects on soil and vegetation. Rapid postfire hazard assessments have traditionally focused on quantifying spatial variations in debris-flow likelihood and volume in response to design rainstorms. However, a methodology that provides estimates of debris-flow inundation downstream of burned areas based on forecast rainfall would provide decision-makers with information that directly addresses the potential for downstream impacts. We introduce a framework that integrates a 24 h lead-time ensemble precipitation forecast with debris-flow likelihood, volume, and runout models to produce probabilistic maps of debris-flow inundation. We applied this framework to simulate debris-flow inundation associated with the 9 January 2018 debris-flow event in Montecito, California, USA. When the observed debris-flow volumes were used to drive the probabilistic forecast model, analysis of the simulated inundation probabilities demonstrates that the model is both reliable and sharp. In the fully predictive model, however, in which debris-flow likelihood and volume were computed from the atmospheric model ensemble's predictions of peak 15 min rainfall intensity, I15, the model generally under-forecasted the inundation area. The observed peak I15 lies in the upper tail of the atmospheric model ensemble spread; thus a large fraction of ensemble members forecast lower I15 than observed. Using these I15 values as input to the inundation model resulted in lower-than-observed flow volumes which translated into under-forecasting of the inundation area. Even so, approximately 94 % of the observed inundated area was forecast to have an inundation probability greater than 1 %, demonstrating that the observed extent of inundation was generally captured within the range of outcomes predicted by the model. Sensitivity analyses indicate that debris-flow volume and two parameters associated with debris-flow mobility exert significant influence on inundation predictions, but reducing uncertainty in postfire debris-flow volume predictions will have the largest impact on reducing inundation outcome uncertainty. This study represents a first step toward a near-real-time hazard assessment product that includes probabilistic estimates of debris-flow inundation and provides guidance for future improvements to this and similar model frameworks by identifying key sources of uncertainty.

Experimental and numerical characterization of screw elements used in twin-screw extrusion

Hot melt extrusion by a co-rotating twin screw extruder is an important process in the pharmaceutical industry. Especially for quality by design aspects, a comprehensive process understanding is indispensable. The performance of conveying elements was determined as critical process parameter, and therefore an experimental and numerical framework was developed to analyze and compare variations. A test rig capable of measuring volume flow, pressure and torque with high accuracy and precision was designed and built. The 3D simulation was performed using computational fluid dynamics (CFD). A stationary model with impulse transmission and an apparent motion of the screws was applied. The experimental data were fitted to the model of Pawlowski, and parameters for the pressure (A1, A2) and power characteristics (B1, B2) were determined. Good agreement between experimental data and the model was observed. The simulation was significantly faster compared to common methods, and the results were consistent with the literature. Systematic investigations of a native and worn screw were performed with CFD resulting in a transport capacity increase and a pressure build up decrease for all tested screw elements. An experimental and simulation setup was generated to assess the performance of co-rotating twin screw elements. The experiments provided high-quality data, and the simulations exhibited high flexibility with low computational effort.

Comparison of feasibility and effectiveness of tunneled dialysis catheter placement with or without DSA guidance: a propensity score-matched cohort study

Background In some resource-limited regions, the placement of tunneled dialysis catheters (TDC) is often preferred under ultrasound guidance rather than fluoroscopy. This study compared ultrasound-and digital subtraction angiography-guided (DSA)-guided TDC in renal replacement therapy. Methods This retrospective cohort study included all TDC placements performed at our hospital between January 2020 and October 2022. We utilized 1:1 propensity score matching (PSM) to balance the demographic and clinical characteristics of the DSA-guided and ultrasound-guided groups. Dialysis prescriptions and actual dialysis completion were assessed using intraclass correlation coefficients (ICC). Multivariable logistic regression analyses determined the risk factors for early termination of dialysis. The differences in adverse events, catheter function, and catheter tip position were evaluated between the two groups. Results The study included 261 patients (142 in the DSA-guided group and 119 in the ultrasound-guided group). After PSM, 91 patients were included in each group, with no significant baseline differences (p > .1). Both groups achieved adequate catheter blood flow and ultrafiltration volumes without deviations from dialysis prescriptions (ICC ≥ 0.75). The DSA-guided group had fewer early dialysis terminations than the ultrasound-guided group (3.3 vs. 12.0%, p = .026). The position of the catheter tip in the right atrium was more consistent in the DSA-guided group (100 vs. 74.2%, p < .001). Conclusion Hemodialysis catheters inserted under DSA guidance exhibited superior performance compared to those inserted under ultrasound guidance, primarily due to more accurate catheter tip positioning. DSA guidance is recommended when ensuring optimal catheter tip placement.

Development and Performance Evaluation Experiment of a Device for Simultaneous Reduction of SOx and PM

Mitigating air pollutants such as SOx and PM emitted from ships is an important task for marine environmental protection and improving air quality. To address this, exhaust gas after-treatment devices have been introduced, but treating pollutants like SOx and PM individually poses challenges due to spatial constraints on ships. Consequently, a Total Gas Cleaning System (TGCS) capable of simultaneously reducing sulfur oxides and particulate matter has been developed. The TGCS combines a cyclone dust collector and a wet scrubber system. The cyclone dust collector is designed to maintain a certain distance from the bottom of the wet scrubber, allowing exhaust gases entering from the bottom to rise as sulfur oxides are adsorbed. Additionally, the exhaust gases descending through the space between the cyclone dust collector and the wet scrubber collide with the scrubbing solution before entering the bottom of the wet scrubber, facilitating the absorption of SOx. In this study, the efficiency of the developed TGCS was evaluated, and the reduction effects based on design parameters were investigated. Furthermore, the impact of this device on ship engines was analyzed to assess its practical applicability. Experimental results showed that increasing the volume flow rate of the cleaning solution enhanced the PM reduction effect. Particularly, when the height of the Pall ring was 1000 mm and the volume flow rate was 35 L/min, the sulfur oxide reduction effect met the standards for Sulfur Emission Control Areas (SECA). Based on these findings, suggestions for effectively controlling atmospheric pollutants from ships were made, with the expectation of contributing to the development of systems combining various after-treatment devices.

Experimental Investigation Of The Flow-Acoustic Interaction In Human Phonation

In the human phonation process, acoustic standing waves in the vocal tract can influence the fluid flow through the glottis. To investigate the amount of two-way coupling between the flow field and the acoustics, the supraglottal flow field has been recorded via high-speed particle image velocimetry (PIV) in a synthetic larynx model for several configurations with different vocal tract lengths. Based on the obtained velocity fields, aeroacoustic source terms were computed. Furthermore, the hydrodynamic pressure in the vocal tract was recorded via wall pressure measurements. The recordings revealed that near a vocal tract resonance frequency, the focal fold oscillation frequency jumps onto the resonance. This is accompanied by a substantial relative increase in aeroacoustic sound generation efficiency. At the same time, the glottal volume flow needed for stable vocal fold oscillation decreases strongly. The pressure measurements showed that acoustic anti-resonances of the vocal tract directly dampen the harmonic content of the hydrodynamic pressure field when matching frequencies. This result shows that back-coupling of the acoustics onto the flow field does not only occur in the case where the vocal fold oscillation frequency and a resonance frequency of the vocal tract match, but also under more other conditions.

Low Volume Gas-Flow Seeding For Highly Resolved Velocimetry Of The Boundary Layer

Ensuring fire safety in polymeric materials, which are inherently flammable but widely used in various industries, is of significant societal and economic importance. This study is part of a broader effort to understand polymer combustion and flame retardant effectiveness at a fundamental level. A major focus is the behavior of polymers burning along a vertical wall, a configuration chosen to study the release of flammable gases during pyrolysis, which contributes to the self-sustaining combustion reaction of a fire. This process occurs predominantly near the polymer surface within the boundary layer, requiring detailed analysis to evaluate flame retardant effectiveness. Our experimental setup replicates polymer pyrolysis using a flame-wall interaction burner with a vertical jet and a small inlet to mimic the release of flammable gases. The primary challenge in this setup is the introduction of seeding particles for Particle Image Velocimetry (PIV) measurements at low volume flow rates, which is complicated by reflections from the wall and the small flow scale relative to the main flow. To address this problem, we have developed a novel piezo-based ultrasonic seeder capable of controlled seeding at extremely low flow rates, thereby improving the accuracy of PIV measurements in non-reactive configurations. This seeder uses a piezo ring to excite a perforated metal membrane, forming uniform aerosol droplets. The design ensures a steady supply of particles, which is critical for evaluating boundary layer conditions. Our results demonstrate the seeder’s ability to maintain sufficient seeding density in the low volume flow region, facilitating detailed velocimetry analysis. The innovative seeder design proves effective in overcoming the limitations of conventional methods and provides new insights into polymer combustion processes and the role of flame retardants.

Development and Performance Evaluation Experiment of a Device for Simultaneous Reduction of SOx and PM

Mitigating air pollutants such as SOx and PM emitted from ships is an important task for marine environmental protection and improving air quality. To address this, exhaust gas after-treatment devices have been introduced, but treating pollutants like SOx and PM individually poses challenges due to spatial constraints on ships. Consequently, a Total Gas Cleaning System (TGCS) capable of simultaneously reducing sulfur oxides and particulate matter has been developed. The TGCS combines a cyclone dust collector and a wet scrubber system. The cyclone dust collector is designed to maintain a certain distance from the bottom of the wet scrubber, allowing exhaust gases entering from the bottom to rise as sulfur oxides are adsorbed. Additionally, the exhaust gases descending through the space between the cyclone dust collector and the wet scrubber collide with the scrubbing solution before entering the bottom of the wet scrubber, facilitating the absorption of SOx. In this study, the efficiency of the developed TGCS was evaluated, and the reduction effects based on design parameters were investigated. Furthermore, the impact of this device on ship engines was analyzed to assess its practical applicability. Experimental results showed that increasing the volume flow rate of the cleaning solution enhanced the PM reduction effect. Particularly, when the height of the Pall ring was 1000 mm and the volume flow rate was 35 L/min, the sulfur oxide reduction effect met the standards for Sulfur Emission Control Areas (SECA). Based on these findings, suggestions for effectively controlling atmospheric pollutants from ships were made, with the expectation of contributing to the development of systems combining various after-treatment devices.

Experimental Investigation Of The Flow-Acoustic Interaction In Human Phonation

In the human phonation process, acoustic standing waves in the vocal tract can influence the fluid flow through the glottis. To investigate the amount of two-way coupling between the flow field and the acoustics, the supraglottal flow field has been recorded via high-speed particle image velocimetry (PIV) in a synthetic larynx model for several configurations with different vocal tract lengths. Based on the obtained velocity fields, aeroacoustic source terms were computed. Furthermore, the hydrodynamic pressure in the vocal tract was recorded via wall pressure measurements. The recordings revealed that near a vocal tract resonance frequency, the focal fold oscillation frequency jumps onto the resonance. This is accompanied by a substantial relative increase in aeroacoustic sound generation efficiency. At the same time, the glottal volume flow needed for stable vocal fold oscillation decreases strongly. The pressure measurements showed that acoustic anti-resonances of the vocal tract directly dampen the harmonic content of the hydrodynamic pressure field when matching frequencies. This result shows that back-coupling of the acoustics onto the flow field does not only occur in the case where the vocal fold oscillation frequency and a resonance frequency of the vocal tract match, but also under more other conditions.

Retrofit of grass swales with outflow controls for enhancing drainage capacity

Reduction of runoff flow peaks and volumes is one of the performance objectives of grass swales in the context of Green Stormwater Infrastructure (GSI). Towards this end, a study of the feasibility of using a retrofitted swale outlet control weir (SOCW) to reduce runoff volume and peak flow, by enhancing swale runoff storage and infiltration into swale soils, was conducted in Luleå, Northern Sweden. Experimental field work consisted of 43 irrigation-driven runoff experiments, mimicking rainfall events with return periods between 1- to 50-years, with a constant intensity and duration of 30 min, in a 30-m long grass swale section. Experimental results confirmed that, under the tested conditions, swales with the retrofitted outflow control, reduced runoff volumes and peak flows. Such reductions ranged from 32 percentage points (for 2-year) to 1 and 4 percentage points (for 50-year return period) for runoff volumes and peak flows, respectively. Outcomes of scenarios with outflow controls clearly indicated a decreasing performance with increasing flow rates (and irrigation event return periods). Furthermore, the retrofitted swale controlled the outflow release during less frequent 20 to 50-year events, which would contribute to reducing flood risks in downstream urban areas.

Boiling induced atomization of liquid film produced by oblique jet impingement on superheated wall

For the thermal management of industrial devices, a reduction in the net coolant flow rate by droplet dispersion from a liquid film is important because it can cause unexpected thermal failure. To understand the process of droplet dispersion from a liquid film better, we experimentally and theoretically evaluated the characteristics of boiling-induced atomization in a liquid film formed by oblique jet impingement on a superheated wall. Atomization processes were visualized using magnified high-speed imaging using a backlight technique. In this study, two types of droplets were observed using high-speed-magnification imaging. These were large droplets that disintegrated from the ligament formed on a relatively high-temperature wall, and small droplets from the ligament formed via bubble bursting in the nucleate boiling regime. For the atomization induced by nucleate boiling, larger droplets were produced via bubble bursting further downstream from the impingement point because the bubble size and liquid film thickness increased. Finally, the total volume of the droplets produced by nucleate boiling was estimated from the frequency of bubble bursting and droplet size measured from the visualization results. The estimation results suggest that the ratio of the total volume flow rate of the ejected droplets to the injection flow rate of the liquid was negligible (2%). Thus, most of the injected liquid eventually reached the wetting front of the sheet, separating it from the wall before drying out.

STUDYING THE IMPACT OF THE VOLUME OF WORK AT THE RAILCAR TRANSFER POINT ON THE NEED FOR TRACK STORAGE CAPACITY FOR BOGIES

Purpose. In the context of military aggression by moscow, export cargo flows, which were largely transported by sea from Ukraine's Black Sea ports, were directed towards western land crossings. At the same time, exporters were trying not only to find new logistics routes but also to increase exports to European countries. This resulted in longer queues at land borders, both road and rail, and the turnover of railcars and their individual components became uncontrollable and unpredictable. The reason for the downtime of cargo in railroad cars at the borders was the limited processing capacity of railcar interchange points and the transshipment capacity of cargo terminals at border stations. One of the elements of the cargo border crossing system, the increase of which will increase the volume of export cargo flow, is the points of change of wagons from 1435 mm gauge to 1520 mm gauge. Therefore, the aim of this study is to determine the required track capacity for storing 1520 mm and 1435 mm gauge bogies under conditions of daily uneven transportation and the stochastic nature of the turnover of cars on the territory of European railways. Methodology. Simulation modeling, mathematical statistics, and inventory management methods were used to study the impact of the workload of a railcar transfer point on track capacity. Results. As a result of the research, the numerical characteristics of a random variable of the number of cars transferred to the transfer point during the day, as well as the value of car turnover in Europe, were obtained. A methodology for determining the required track capacity for storing bogies based on simulation modeling of the operation of the railcar interchange points was developed. The dependence of the guaranteed stock of bogies of 1435 mm gauge at the station on the daily number of cars serviced at the railroad car transfer point was obtained. Practical significance. The obtained dependences of the required capacity of the tracks for storing bogies on the daily number of cars arriving at the transfer point will allow us to check and, if necessary, bring the existing track development of border stations into line with the calculated volumes of work.

Physical enhancement of older adults using hyperbaric oxygen: a randomized controlled trial

IntroductionAging is associated with a progressive decline in the capacity for physical activity. The objective of the current study was to evaluate the effect of an intermittent hyperbaric oxygen therapy (HBOT) protocol on maximal physical performance and cardiac perfusion in sedentary older adults.MethodsA randomized controlled clinical trial randomized 63 adults (> 64yrs) either to HBOT (n = 30) or control arms (n = 33) for three months. Primary endpoint included the maximal oxygen consumption (VO2Max) and VO2Max/Kg, on an E100 cycle ergometer. Secondary endpoints included cardiac perfusion, evaluated by magnetic resonance imaging and pulmonary function. The HBOT protocol comprised of 60 sessions administered on a daily basis, for 12 consecutive weeks, breathing 100% oxygen at 2 absolute atmospheres (ATA) for 90 min with 5-minute air breaks every 20 min.ResultsFollowing HBOT, improvements were observed in VO2Max/kg, with a significant increase of 1.91 ± 3.29 ml/kg/min indicated by a net effect size of 0.455 (p = 0.0034). Additionally, oxygen consumption measured at the first ventilatory threshold (VO2VT1) showed a significant increase by 160.03 ± 155.35 ml/min (p < 0.001) with a net effect size of 0.617. Furthermore, both cardiac blood flow (MBF) and cardiac blood volume (MBV) exhibited significant increases when compared to the control group. The net effect size for MBF was large at 0.797 (p = 0.008), while the net effect size for MBV was even larger at 0.896 (p = 0.009).ConclusionThe findings of the study indicate that HBOT has the potential to improve physical performance in aging adults. The enhancements observed encompass improvements in key factors including VO2Max, and VO2VT1. An important mechanism contributing to these improvements is the heightened cardiac perfusion induced by HBOT.Trial registrationClinicalTrials.gov Identifier NCT02790541 (registration date 06/06/2016).

Modeling and mitigation of vortex formation in ejector deep hole drilling with smoothed particle hydrodynamics

AbstractEjector deep hole drilling achieves high-quality boreholes in production processes. High feed rates are applied to ensure a high productivity level, requiring reliable chip removal from the cutting zone for a stable process. Therefore, a constant metalworking fluid flow under high volume flow rates or high pressure is required. Experimental results show a vortex formation at the outer cutting edge. This vortex can lead to delayed chip removal from the cutting zone, and ultimately, it can lead to chip clogging and result in drill breakage due to increased torque. This paper investigates modified drill head designs using the smoothed particle hydrodynamics method. The investigated modifications include various designs of the chip mouth covering. Besides graphical analysis based on flow visualizations, flow meters are placed at the tool’s head to evaluate the impact of the modifications on the flow rate and possible increased resistance and relocation of the fluid flow from the outer cutting edge to other parts of the tool. The simulation results for the reference design show the experimentally observed vortex formation, validating the simulation model. By adding the tool’s rotation in the SPH simulation, which is not included in the experiments for observation reasons, the vortex formation is positively influenced. In addition, some designs show promising results to further mitigate the vortex formation while maintaining a sufficient fluid flow around the cutting edges.

The use of the Isolation Forest model for anomaly detection in measurement data

The subject of the research is the Isolation Forest model, which is a powerful and efficient tool for detecting anomalies in measurement data and outliers, applicable in various fields where ensuring high accuracy and reliability of measurements is important. The goal of the study is to apply the Isolation Forest model to identify unusual or anomalous patterns that differ from typical patterns in the output data. This is achieved by isolating anomalous patterns from normal ones through the construction of multiple different decision trees. The task of the research is to detect outliers in data obtained during the preparation for international comparisons on the state primary standard for mass and volume flow rate of fluid, mass and volume of fluid flowing through a pipeline, by measuring with a сoriolis flowmeter. Data collected during metrological studies undergo processing by the model to detect anomalies. This model analyzes the data and identifies anomalous or outlier values that may indicate systematic or random measurement errors. It enables quick and efficient detection of even the smallest deviations in the data, helping to maintain high accuracy and reliability of measurement results. The main methods for detecting outliers in statistical analysis, which are distribution-independent, are the Grubbs' criterion, interquartile range distribution, and standard deviation. They are sensitive to sample size but are simple and understandable tools. However, the Isolation Forest model also has its limitations, particularly it can be resource-demanding for large datasets. Additionally, it is necessary to consider that using the model requires proper parameter tuning to achieve optimal results. The results of the research include assessment of the Isolation Forest model's effectiveness by comparing it with traditional outlier detection methods. Comparative analysis of the results of different approaches to the same task is an effective method for evaluating the model's performance. Conclusion. The article concludes with the perspective of further research development in this direction. The work will focus on further developing methods for detecting anomalies in measurement data and improving the accuracy and reliability of measurement results in various application fields, which can find broad applications in science and industry.