Average Pressure Difference Research Articles

Soft plant root structure-media flow interactions: Exploring the adverse effect of lead contamination in North-Eastern Indian rice

We experimentally investigate the effect of lead (Pb2+) contamination on the roots of an Assamese rice line variety Lachit using a heavy metal analyzing fluidic tool. To demonstrate the adverse effects of lead contamination on rice seedlings in a controlled environment, we have performed a number of multidisciplinary experiments. Also, we develop a numerical model in this endeavor to predict the Michaelis–Menten kinetics parameters, which are used to depict the lead transport phenomenon following soft root structure-media flow interactions. We show that increased inlet lead concentration of the media solution leads to a reduction in root growth exponentially in the developed fluidic device. As supported by the Raman spectra analysis, the drastic metabolic changes are visible under lead contamination. Our results revel that, in comparison to the control condition, lead accumulation results in a decrease in the uptake of nitrogen and also, the metallic nutritional components (K+, Na+, and Ca2+). Under lead contamination, the average osmotic pressure difference at the root surface is seen to be less than in the control situation. The inferences drawn from the current research shed light on the detrimental effects of lead contamination on rice roots, which have the potential to significantly lower agricultural yields and threaten food security in areas where rice is the primary food source.

Initial results of the READY registry: comparison of visual and physiological lesion characterization and the effect of hydrostatic pressure correction

Abstract We aimed to compare resting Pd/Pa, FFR, and distal RFR values with and without hydrostatic pressure correction. Our main goal was to assess the influence of this correction on cut-off value-based decision-making for each physiological parameter. Data from patients enrolled in two centers of the READY registry (NCT04857762) were analyzed. Center 1 employed catheter and pressure sensor height differences defined from lateral angiographic projection for hydrostatic pressure correction, while Center 2 utilized average pressure differentials from published data. In Center 1, the height difference underlying the hydrostatic pressure correction did not differ significantly from the average values published in previous publication (-5.22±1.1cm for LAD, 2.44±1.1cm for CX, and 1.63±2.8cm for RCA). Consequently, FFR and distal RFR values corrected with average pressure differentials rarely yielded different cut-off-based characterizations compared to individually measured corrections (2.4%). A total of 42 measurements were evaluated in Center 1 (33 patients) and 40 measurements in Center 2 (40 patients). Stenoses were characterized using resting Pd/Pa (0.91 ± 0.05), FFR (0.80 ± 0.08), distal RFR (0.86 ± 0.09) and ΔRFR (0.07 ± 0.07) values. Regarding all the investigated vessels, statistically significant differences were observed in FFR (0.80 ± 0.08 vs 0.81 ± 0.08; p < 0.001), distal RFR (0.86 ± 0.09 vs 0.87 ± 0.09; p < 0.001), and ΔRFR (0.053 ± 0.04 vs 0.047 ± 0.04; p = 0.014) before and after correction. These changes after hydrostatic correction were driven dominantly by the LAD measurements being LAD stenoses constituted the majority of the cases (73.2%). Overall (n=82), hydrostatic pressure correction modified cut-off-based categorization in 24 (29.3%) cases for Pd/Pa, and 19 (23.2%) cases for both distal RFR and FFR measurements. Notably, ΔRFR assessment also changed in 22.2% of cases after correction. Among LAD stenoses (n=60), hydrostatic pressure correction altered cut-off-based characterization in 22 (36.7%), 19 (31.7%), and 17 (28.3%) cases of resting Pd/Pa, distal RFR, and FFR measurements, respectively. Hydrostatic pressure correction offers the potential to enhance the accuracy of intracoronary physiological measurements, especially for LAD stenoses. Our data suggest that the published average pressure differences of each coronary segment can be used for correction.Lateral view and delta RFRIndividual vs Average LAd correction

Stabilized equal lower-order finite element methods for simulating Brinkman equations in porous media

This paper demonstrates the mixed formulation of the Brinkman problem using linear equal-order finite element methods in porous media modelling. We introduce Galerkin least-squares (GLS) and least-squares (LS) finite element methods to address the incompatibility of finite element spaces, treating velocity, pressure, and vorticity as independent variables. Theoretical analysis examines coercivity and continuity, providing error estimates. Demonstrating resilience in theoretical findings, these methods achieve optimal convergence rates in the L 2 norm by incorporating stabilization terms with low-order basis functions. Numerical experiments validate theoretical predictions, showing the effectiveness of the GLS method and addressing finite element space incompatibility. Additionally, the GLS method exhibits promising capabilities in handling the Brinkman equation at low permeability compared to the LS method. The study reveals an increase in the average pressure difference in the Brinkman problem compared to the Stokes equations as the inlet velocity rises, providing insights into the behaviour of Brinkman equations.

Abstract P106: Association of long term blood pressure variability and Major Cardiovascular events in patients with primary aldosteronism

Objective: Long-term blood pressure variability (BPV) is associated with an increased risk of major cardiovascular events (MACE), but it is rarely reported in patients with primary aldosteronism (PA). We aim to investigate the association between long-term BPV and cardiovascular events in patients with PA. Methods: This was a retrospective cohort study which conducted at the Hypertension Center of People’s Hospital of Xinjiang Uygur Autonomous Region from January 2006 to December 2021. The study included patients with PA aged over 30 years. The primary outcome was the incidence of major cardiovascular events during the follow-up, which extended until June 2023. The BPV index encompassed four parameters: standard deviation (SD), coefficient of variation (CV), average real variability (ARV), and maximum and minimum blood pressure difference (MMD). Multivariate analysis using logistic regression was performed, adjusting for demographic variables such as age, sex, body mass index, as well as clinical characteristics including smoking and alcohol consumption. Results: A total of 2,380 patients with PA were ultimately enrolled in this study. Access to clinic blood pressure was ensured at least three times during follow-up visits, with a minimum follow-up interval of 1 month. During a median follow-up of3.6 years, there were 124 cases of MACE. The mean age of the participants was 49.36 years, with men accounting for 1,288 cases. The average blood pressure recorded was 135 mmHg. After adjusting for confounding factors such as age, sex, smoking, alcohol consumption, BMI and cardiovascular risk factors, the systolic BPV (SD, CV, ARV) was found to be significantly associated with MACE (OR= 1.03, CI 1.02-1.05; P<0.05). In the group of mean SBP≥130mmHg, SBP variability had a significant association with MACE (OR: 1.03; CI: 1.01-1.06; P<0.05). However, no significant correlation between SBP variability and MACE in group of mean SBP <130mmHg (P>0 .05). Conclusion: Focusing on long-term systolic BP SD, CV, and ARV in patients with primary aldosteronism may help to prevent the occurrence of cardiovascular events.

Optimal control for district heating systems based on imbalance analysis of pipe networks

In district heating (DH) systems, the transmission and distribution process occupy large amount of energy consumption. Hydraulic and thermal imbalance in pipe networks often lead to uneven heating, affecting user comfort and resulting in energy losses. To solve this problem, this study investigates the root causes of hydraulic and thermal imbalances in DH systems. Key factors have been identified such as initial flow rates, initial loads, and positions in the network of end-users. And the relationship between hydraulic and thermal imbalances have been analyzed. Building on this analysis, we further propose a novel strategy for differential pressure set-point adjustment. This strategy is developed based on a quantitative understanding of the flow rate changes and positions of end-users. It aims to rectify imbalances efficiently, thus enhancing the overall performance of the network. The effectiveness of the proposed strategy is validated through comparative analysis with the conventional constant differential pressure (CCDP) control strategy and an exist variable differential pressure (VDP) control strategy. Results demonstrate significant improvements in network performance, including enhanced stability and reduced energy losses. The proposed strategy reduces the average pressure difference in the main pipe by up to 10.9 %, improves the supply and return temperature difference by 10.9 %, and maintains valve openings above 70 % during peak periods. Additionally, it achieves 23.5 % energy savings in transmission and distribution, highlighting its potential to enhance system performance and efficiency. In addition, this strategy is more in line with the actual situation of end-user demand change for valve adjustment.

Study of piston offset inhibition method based on the biased center port

The linear compressor is one of the main energy-consuming components in domestic and space refrigeration systems. Due to the asymmetric leakage in the clearance, the piston offset unavoidably causes the piston to deviate from its designed equilibrium position and worsens the compressor performance. In this paper, a new method is proposed to inhibit the piston offset. A biased center port is employed to direct gas from the back chamber to the front at the position close to the back chamber to balance the pressure on the two sides of the piston. To verify this method, a numerical simulation was performed to calculate the mass flow through the clearance and center port channel, and the average pressure difference across the piston. An experimental bench was established to compare the offset of the structures with no center port, unbiased center port and biased center port. Results show that the biased center port can almost eliminate the piston offset at the designed operating condition.

A comparative analysis of age-related alterations in foot biomechanics and visual input in pre-adolescent and adolescent children with normal body mass index

Background: Foot biomechanics undergo age related changes and visual input may be important for postural stability and stance dynamics. This study aimed to investigate how age-related alterations in foot biomechanics and visual input interact to influence postural stability and stance dynamics in children aged 6 to 19 years. Materials and methods: Prospective observational study was conducted after getting permission from Institutional Ethics Committee. Informed consent was obtained before collecting data. OHM3000 used for collecting data. Data was collected for bipedal stance test, stabilometry test with eyes open and eyes closed, and dynamic stance test during walking with predefined protocol. Result: Statistically significant difference in maximum pressure, average pressure, foot area and foot length are exhibited in both feet with higher values in adolescents as compared to pre-adolescents. Maximum lateral deviation was significantly less in adolescent with eyes open toward right feet as compare to preadolescents and the difference was lost with eyes closed. Maximum pressure, average pressure, foot contact area and forefoot maximum pressure in both feet were statistical significance. Conclusion: Increased maximum pressure, average pressure, foot area and foot length indicating physical growth and higher load-bearing capacities in adolescents. Weight distribution over the forefoot and hindfoot remained consistent across age groups even if significant changes shown in foot size and pressure. Visual input significantly improved postural stability in both groups. Adolescents show better postural stability probably due to foot maturation. During walking, adolescents showed increased maximum and average pressures, especially in forefoot. Keywords: foot; clinical anatomy; biomechanics; adolescents; children; postural stability; gait; visual input

Study on a flexible rod-type valved linear compressor without piston offset

Over the past few decades, research has been increasing on valved linear compressors in cryogenics and refrigeration. To guarantee the high performance of the compressor, the piston needs to move at the designed maximum stroke. However, most of the compressors suffer from piston offset. Due to the reduction of stroke, the piston offset greatly deteriorates the compressor's performance. To solve this problem, a valved linear compressor with a flexible rod connecting dual pistons is proposed to eliminate the offset. The flexible rod is characterized by large axial stiffness and small radial stiffness. The large axial stiffness ensures that the two pistons move simultaneously. It counteracts the average differential pressure force on the dual pistons. The small radial stiffness allows frictionless movement of the dual pistons in the dual cylinders with slight non-coaxial deformation. A prototype was designed numerically and verified experimentally. In a none-flexible-rod compressor, the piston stroke can only travel up to 60% of its design value because of the offset. On the contrary, the flexible rod-type compressor can perform without piston offset.

Association between Mitral Valve Mean Pressure Gradient and Atrial Fibrillation in Patients with Rheumatic Mitral Stenosis: A Cross-Sectional Study

Plain Language SummaryRheumatic mitral stenosis, particularly for women and young patients, is one of the most prevalent cardiovascular conditions in the world. The disease has become a global burden in recent decades. Common complications of rheumatic mitral stenosis include atrial fibrillation and stroke. Individuals with rheumatic mitral stenosis who develop AF are at increased risk of heart failure and thromboembolic events. Echocardiography is the preferred method for diagnosis, assessment of severity, and hemodynamic consequences of mitral stenosis. The mitral valve mean pressure gradient, a well-established echocardiographic parameter representing the average pressure difference between the left atrial and the left ventricle during diastole, can reflect the consequences of mitral stenosis and have a prognostic role. Individuals with high mitral valve mean pressure gradient warrant greater attention to prevent atrial fibrillation.

Lasix for the prevention of de novo postpartum hypertension: a randomized placebo-controlled trial (LAPP Trial)

Birthing people with de novo postpartum hypertensive disorders continue to be among the populations at highest risk for severe maternal morbidity. Randomized controlled trials demonstrate a benefit of oral loop diuretics in decreasing postpartum hypertensive morbidity in patients with an antenatal diagnosis of preeclampsia. It is not known whether this same therapy benefits patients at risk for new-onset postpartum hypertension. This study aimed to evaluate whether oral furosemide can reduce the risk for de novo postpartum hypertension among high-risk birthing people by reducing postdelivery blood pressure. From October 2021 to April 2022, we conducted a randomized triple-masked placebo-controlled clinical trial of individuals at high risk for de novo postpartum hypertension at a single university-based tertiary care medical center. A total of 82 postpartum patients with no antenatal diagnosis of chronic hypertension or a hypertensive disorder of pregnancy who were at high risk for the development of de novo postpartum hypertension based on a prespecified risk factor algorithm were enrolled after childbirth. The participants were randomly assigned in a 1:1 ratio to a 5-day course of 20-mg oral furosemide daily or identical-appearing placebo starting within 8 hours of delivery. Participants were followed for 6 weeks postpartum using Bluetooth-enabled remote blood pressure monitoring and electronic surveys. The primary outcome was mean arterial pressure averaged over the 24 hours before discharge or the 24 hours before antihypertensive therapy initiation. The study was powered to detect a 5 mm Hg difference in average mean arterial pressure (standard deviation, 6.4 mm Hg) with 90% power at an alpha of 0.05, requiring a sample size of 41 per group. Secondary outcomes included the rate of de novo postpartum hypertension, readmission data, other measures of hypertensive and maternal morbidity, breastfeeding data, and drug-related neonatal outcomes. The primary outcome was assessed in 80 of the 82 participants. Baseline characteristics were similar between the groups. There was no significant difference in average mean arterial pressure in the 24 hours before discharge (or antihypertensive initiation) in the furosemide group (88.9±7.4 mm Hg) compared with the placebo group (86.8±7.1 mm Hg; absolute difference, 2.1 mm Hg; 95% confidence interval,-1.2 to 5.3). Of the 79 participants for whom secondary outcomes were assessed, 10% (n=8) developed de novo postpartum hypertension and 9% (n=7) were initiated on antihypertensive therapy. Rates were not significantly different between the groups (P=.71 and P>.99, respectively). De novo postpartum hypertension is a common phenomenon among at-risk patients, warranting close monitoring for severe hypertension and other maternal morbidity. There is insufficient evidence to suggest that furosemide reduces average mean arterial pressure in the 24 hours before discharge from the delivery hospitalization (or antihypertensive medication initiation) compared with placebo.

Thermodynamic modeling and analysis of cascade hydrogen refuelling with three-stage pressure and temperature for heavy-duty fuel cell vehicles

Recently, the development of heavy-duty fuel cell vehicles (HDFCVs) has received intense attention. Unlike the refuelling protocol of SAE J2601 for light-duty fuel cell vehicles, the SAE J2601-2 for HDFCVs does not propose a specific filling strategy but only specifies the limits that need to be observed for safety. Refuelling data for HDFCVs at hydrogen refuelling station (HRS) shows that refuelling parameters are often set conservatively, resulting in long refuelling time. To shorten the refuelling time, energy consumption and power demand of the cooling system, we establish a detailed three-stage pressure filling model to study the effects of pressure ramp rate (PRR), initial pressure, number of onboard tanks and precooling temperature on the filling time. Then, a three-stage temperature precooling method is proposed simultaneously, whose cooling energy and power of the heat exchanger are compared with the single-stage temperature precooling method. Research shows that three-stage and two-stage pressure filling can reduce the average pressure difference between the station-side and the vehicle-side storage tanks, thereby reducing the Joule-Thomson heat generated by the reduction valve throttling and the heat exchanger energy consumption. Increasing the PRR and initial pressure can significantly and directly shorten the filling time. Increasing the number of onboard tanks and decreasing precooling temperature have little effect on the filling time but reduce the final hydrogen temperature in the onboard tank, which is beneficial to increase the PRR further to shorten the filling time. Within the ambient temperature range set in this article, compared with the single-stage temperature precooling method, the three-stage temperature precooling method can reduce the maximum peak cooling power by 16.69%–17.38% without increasing the total cooling energy of the heat exchanger and onboard tank's final hydrogen temperature, reducing equipment investment in cooling systems. This research is significant for optimizing HRS design and operation strategies.

Transcatheter aortic valve replacement in the treatment of bicuspid aortic stenosis with "down-size" interventional valves: procedural and mid-term follow-up.

Due to the influence of anatomical structure, replacing the bicuspid valve using transcatheter aortic valve replacement (TAVR) would increase the risk of perivalvular leakage and conduction block, affecting the hemodynamic effect of the interventional valve. In this study, for bicuspid and tricuspid valves, we implemented different valve selection strategies to explore the safety and effectiveness of TAVR in the treatment of bicuspid aortic stenosis with "down-size" interventional valves using the VenusA-valve system. The operation was performed with the VenusA-valve via transfemoral approach. The selected valves were appropriately sized based on the results of transthoracic echocardiography (TTE), contrast-enhanced computed tomography (CT), and the morphology of intraoperative pre-dilation balloons. For tricuspid valve cases, the VenusA valve is usually larger than the annulus diameter, whereas the "down-size" approach was adopted for bicuspid aortic valve (BAV) cases. The shape of the pre-dilation balloon allowed further sizing of the annulus diameter by the degree of lumbar constriction of the balloon, aiding in intervention valve size selection, particularly in cases of BAVs. A total of 65 patients underwent TAVR for aortic stenosis with VenusA-valve systems. Of these, 29 cases had a BAV and 36 cases had a tricuspid aortic valve (TAV). The distribution of VenusA-valve sizes differed between TAV and BAV cases (P=0.007). Furthermore, there was a significant decrease in the average mean gradient in TAV patients from 54.7 to 12.2 mmHg (P<0.001), and in BAV patients from 61.6 to 14.3 mmHg (P<0.001). The percentage of paravalvular leakage greater than mild was 6.90% in the BAVs and 5.56% in the TAVs at procedural outcomes (P=0.955). The mean follow-up period was 22.23 months (range, 12 to 39 months). The proportion of New York Heart Association (NYHA) class III/IV decreased from 78.5% preoperatively to 11.3% at the last follow-up (P<0.001). A total of 27 patients with TAV and 19 patients with BAV underwent TTE at 1-year follow-up after operation. There was no significant contrast in the average pressure difference between TAVs and BAVs at 1-year follow-up (11.9 vs. 14.3 mmHg, P=0.18). The VenusA-valve for TAVR produced positive clinical outcomes and valve functionality in both BAVs and TAVs. In the case of BAVs, selecting a smaller interventional valve size was deemed viable.

A new type of velocity averaging tube vortex flow sensor and measurement model of mass flow rate

Accurate mass flow rate measurement of fluid is one of the key technologies to ensure product quality and utilization of energy resources. However, the accuracy of traditional combined measuring devices is limited. In this paper, a new type of velocity averaging tube vortex flow sensor (VATV) is designed, and the mass flow rate measurement model is proposed and analyzed to achieve the high precision measurement of mass flow rate. The size, shape and structure of the VATV are designed in this study and there are no moving parts inside the integrated VATV. The method of double differential pressure is proposed to achieve the measurement of the average differential pressure signal and differential pressure fluctuation signal. Then, the method of Empirical Wavelet Transform (EWT) is used to extract the vortex shedding frequency from the differential pressure fluctuation signal. It indicated that the proposed VATV achieves an accuracy of ±0.50%, and the repeatability is also lower than 0.07%. A remarkable improvement of accuracy is achieved compared to the original combined measurement devices. The proposed sensor shows good prospect for the detection of gas-liquid two-phase flow such as wet stream due to the feature of strong anti-interference, high stability and reliability.

Hyperuricemia and coronary heart disease: The mediating role of blood pressure and thrombospondin 3

Background & aimsAlthough hyperuricemia is a known risk factor for coronary heart disease (CHD), little is known about the role of blood pressure in mediating this association. The purpose of this study is to investigate the role of blood pressure-related indicators and Thrombospondin 3 (THBS3) in the association between hyperuricemia and CHD. Methods and resultsOur observational epidemiology study included 593 CHD cases and 760 controls from a residential stable sample. We also chose 43 new CHD patients and 43 controls to test the expression levels of THBS3 using ELISA kits. We used logistic regression models and mediating effect analysis to investigate the relationships between hyperuricemia and CHD, as well as the mediating role of blood pressure-related indicators and THBS3. In the general population (OR: 2.001 [95% CI: 1.528–2.622]), male population (OR: 1.591 [95% CI: 1.119–2.262]), and female population (OR: 2.813 [95% CI: 1.836–4.310]), hyperuricemia is an independent risk factor for CHD. In general, average systolic blood pressure (SBP) and average pulse pressure difference (PPD) mediated 3.35% and 4.59%, respectively, of the association between hyperuricemia and CHD, and 6.60% and 6.60% in women. However, in the male population, we have not yet found that blood pressure-related indicators had a significant mediating effect. Meanwhile, we found that THBS3 mediated 19.23% of the association between hyperuricemia and CHD. ConclusionsAverage SBP, PPD, and THBS3 all play a role in the association of hyperuricemia and CHD. In the female population, similar mediating results in blood pressure-related indicators were observed.

A randomized open label, parallel-group study to evaluate the hemodynamic effects of Cafedrine/Theodrenaline vs Noradrenaline in the treatment of intraoperative hypotension after induction of general anesthesia: the “HERO” study design and rationale

Objective Intraoperative arterial hypotension (IOH) is associated with poor patient outcome. This study aims to compare the hemodynamic effects of Cafedrine/Theodrenaline (C/T) and Noradrenaline (NA) for the treatment of hypotension in patients who develop IOH after anesthesia induction. Research design and methods This is a national, randomized, parallel-group, multicenter, and open-label study. Adult patients (≥50 years, ASA-classification III–IV) who undergo elective surgery will be included. When IOH (MAP <70 mmHg) develops, C/T or NA will be given as a bolus injection (“bolus phase”, 0–20 min after initial application) and subsequently as continuous infusion (“infusion phase”, 21–40 min after initial application) to achieve MAP = 90 mmHg. Hemodynamic data are captured in real time by advanced hemodynamic monitoring. Results Primary endpoints, i.e. the treatment-related difference in average mean arterial pressure (MAP) during the “infusion phase” and the treatment-related difference in average cardiac index during the “bolus phase” are assessed (fixed-sequence method). Non-inferiority of C/T compared to NA in achieving 90 mmHg (MAP) when applied as continuous infusion is hypothesized. In addition, superiority of C/T over NA, applied as bolus injection, in increasing cardiac index is postulated. It is estimated that 172 patients are required to establish statistical significance with a power of 90%. After adjusting for ineligibility and dropout rate, 220 patients will be screened. Conclusion This clinical trial will yield evidence for marketing authorization of C/T applied as continuous infusion. Additionally, the effects of C/T compared to NA on cardiac index will be assessed. First results of the “HERO”-study are expected in 2024. DRKS identifier: DRKS00028589. EudraCT identifier: 2021-001954-76.

Upscaled dynamic capillary pressure for two-phase flow in porous media

A closed expression for the average pressure difference (often called the macroscopic dynamic capillary pressure in the literature) is proposed for two-phase, Newtonian, incompressible, isothermal and creeping flow in homogeneous porous media. This upscaled equation complements the average equations for mass and momentum transport derived in a previous article. Consistently with this work, the expression is derived employing a simplified version of the volume-averaging method that makes use of elements of the adjoint method and Green's formula. The resulting equation for the average pressure difference is novel, as it shows that this quantity is controlled by the pressure gradient (and body forces) in each phase, as well as interfacial effects, and is applicable to situations in which the fluid–fluid interface is not necessarily at its steady position. The effective-medium quantities associated with the sources are all obtained from the solution of a single adjoint (or closure) problem to be solved on a (periodic) unit cell representative of the process. The average pressure difference predicted by the derived expression is validated through excellent comparisons with direct numerical simulations performed in a model porous structure.

Pre-Compressed Foam Sealing Tapes to Seal Joints between Building Envelope Components Watertight: An Experimental Assessment

Currently there is gaining interest in pre-compressed foam sealing tapes to seal joints watertight between different building envelope components. Little to no information is available on the parameters affecting the resistance of these foam tapes to driving rain. On the other hand, several research studies have shown that water leakages can be expected at relatively low-pressure differences and that drainage should be provided. Therefore, a study was designed to on the one hand assess the material and installation parameters that affect the watertightness of pre-compressed polyurethane foam sealing tapes impregnated with an acrylic polymer dispersion and on the other hand evaluate the potential of providing drainage possibilities, either as a two-barrier system or by means of integrated drainage cavities. It was found that the joint width, the presence of an airtight coating, and the position of the tape relative to the exterior surface affected the watertightness of the sealed joints. Notably, 87% of the evaluated foam tapes applied as a single barrier showed water leakages at pressure differences of 600 Pa or lower. Foam tapes with integrated drainage cavities, on the other hand, resulted in watertight joints up to an average pressure difference of 825 Pa.

Re-Injection of Formation Water and Sea Water to Increase Oil Recovery from Sandstone Rocks: A Laboratory Experiment Under Room Conditions

Laboratory tests and field applications show that low-salinity water flooding could lead to significant reduction of residual oil saturation. There has been a growing interest with increasing number of low-salinity water flooding studies. However, there are few quantitative studies on the effect of using sea-water injections on oil recovery. As oil production continues, a drop-in reservoir pressure will occur due to the loss of reservoir fluids, and this drop-in pressure will lead to a decrease in oil production. The reservoir pressure is maintained by the water injection process. Where sea-water is injected into the aquifer area below the oil area to support the tank pressure. This study presents a laboratory investigation of the effect of salinity injection water on oil recovery, permeability, and relative permeability in the water flooding process. This study was conducted using several samples of sandstone saturated with oil by placing them in the reservoir conditions by placing them in a vacuum oven to ensure complete saturation of the samples with oil and then extracting the oil from them using liquid permeability where the samples are injected. With the formation water until reaching the recovery plateau and obtaining an average reading, the flow, permeability and pressure difference are measured, as well as the relative permeability and recovery factor, then the samples are injected again with sea water and the new results are recorded through seawater injection. The results of this study showed an increase in oil recovery with decrease in residual oil saturation and increase in the recovery factor.

Filtration of mechanically activated seawater

This article presents the results of a comprehensive experimental study of the impact of mechanical activation (vibration activation, vibro-mechanical activation) on the processes of seawater filtration through the filter partitions, performed on physical models in a laboratory setting closely resembling industrial conditions. Over the course of the experimental work, the main indicators of the processes of seawater filtration were determined based on the constructed curves that characterize the dependence of this processes on the applied modes of mechanical action, specifically the average throughput of paper, fabric and bulk filters (sand, gravel) when filtering seawater without its preliminary activation, after its preliminary vibration activation and vibration mechanical activation for 120 seconds under the same conditions (air temperature in the room, initial water temperature, volume of filtered liquid, its mass, volume and height of the column, etc.); average pressure difference, as well as average volume flow. It has been established that vibration activation and vibro-mechanical activation of seawater contributes to an increase in the throughput through the paper filter: vibration activation (up to 60%), vibro-mechanical activation (up to 78%); fabric filter: vibration activation (up to 8%), vibo- mechanical activation (up to 71%); bulk filter: vibration activation (up to 41%); vibrо-mechanical activation (up to 116%). It is established that there is a clear advantage of vibrо-mechanical activation over vibration activation: paper filter (by 18%), fabric filter (63%), bulk filter (75%). Along with this, the study of seawater before and after mechanical action was reflected in the form of an analysis of changes in physical and chemical parameters such as temperature, pH value, density, salinity, and the total amount of dissolved solids that affect the result.

Numerical Study on Vortical Flow Structure and Performance Enhancement of Centrifugal Compressor Impeller

The performance and efficiency of a centrifugal compressor are usually affected by the highly complex 3-dimensional flow structures which develop in the flow field of the compressor. Several experiments and research using numerical analysis have been reported, however, there are still many unknown physical phenomena that need to be studied, in order to optimize the design and improve the efficiency of turbomachines, especially those installed on hydrogen-powered fuel cell electric vehicles (FCEVs). In this study, the 3-dimensional vortex structures were analyzed using the critical-point theory and the probabilistic definitions, for an air supply device mounted on the commercial hydrogen FCEVs. The behavior of the complex 3-dimensional vortex structures at the design flow rate and low flow rate were elucidated. A tip leakage vortex was observed to develop at the leading edge of the main blade at all flow rates, which caused interference to the splitter blade. At 60% of the design flow rate, a vortex breakdown occurred at the tip leakage vortex near the leading edge of the main blade, and a reverse flow at 50% chord length of the main blade’s suction surface. The boundary layer which developed at the leading edge of the main blade’s suction surface at all flow rates led to the creation of a hub separation vortex by interfering with the boundary layer developed at the hub surface as a result of the centrifugal force. In addition, the boundary layer developed at the hub and shroud surface created a horseshoe vortex as it moved downstream and interfered with the leading edge of the main blade and splitter blade. It was confirmed that the behavior of the tip leakage, hub separation, and horseshoe vortex structures determined the aerodynamic performance of the centrifugal compressor. The average pressure difference improved by 1.47% of the entire flow rate after optimizing the compressor design.