Reduction In Flow Rate Research Articles

Salivary Gland Dysfunction Secondary to Cancer Treatment.

The number of cancer survivors are increasing and so are the oral toxicities from cancer therapy. Most patients receiving treatment for cancer develop some form of oral adverse events including, but not limited to, mucositis, opportunistic infections, dry mouth, and/or osteonecrosis of the jaw. One of the most common complications from head and neck cancer radiation therapy is salivary gland dysfunction (SGD). SGD is an umbrella term that includes the subjective sensation of dry mouth (xerostomia) and hyposalivation (objective reduction of the salivary flow rate). Dry mouth in cancer patients may lead to functional defects (e.g., eating, speaking, and swallowing), increase the risk of dental caries and oral candidiasis, and can have a negative effect on the nutritional and psychological status of the patients. The aim of this mini review was to summarize the current criteria for diagnosis and management of SGD associated with cancer treatment.

Impacts of different exhaust thermal management methods on diesel engine and SCR performance at different altitude levels

Exhaust thermal management is important for efficient operation of the diesel engine aftertreatment system to meet emissions requirements at low speed and low load conditions. In order to study the impacts of exhaust thermal management strategies on diesel engine performance and SCR conversion efficiency at different altitudes, the effects of the altitudes (2000, 1000, and 0 m), intake throttling, exhaust throttling, and post injection were experimentally studied with a high-pressure common-rail diesel engine that consisted of a diesel oxidation catalyst (DOC) and a selective catalytic reduction (SCR) aftertreatment device. The results showed that the exhaust temperature and the SCR conversion efficiency were improved by intake or exhaust throttling or post injection at any altitudes. However, the intake or exhaust throttling resulted in engine air flow rate reduction, combustion deterioration, brake specific fuel consumption (BSFC) increase, and NOx emissions decrease. When the intake throttling and the exhaust throttling were compared with the same pressure change amplitude, the intake throttling provided better effects on exhaust temperature enhancement, SCR conversion efficiency increase, while the exhaust throttling provided worse effects on BSFC. As the altitudes increased, the impacts of the intake or exhaust throttling on the SCR conversion efficiency and the BSFC became more prominent. Moreover, increasing post injection fuel quantity or retarding post injection timing made combustion worse, BSFC higher, and NOx emissions lower with benefits of exhaust gas temperature increase and SCR conversion efficiency increase. Therefore, post injection is an effective method of exhaust thermal management and should be adopted first. Then, intake throttling should be used. Finally, exhaust throttling can be considered.

JOINT DEVELOPMENT: OIL AND GAS RESOURCES

Commercial production of unconventional oil and gas resources will be difficult to achieve without large-scale engineering measures, let alone the additional operating costs, increasingly stringent safety and environmental requirements, fluctuating low oil and gas prices, and so on, all of which will undermine investors' confidence. As a reason, unconventional techniques to steering the exploration and production of nontraditional oil and gas production are urgently required. As a conclusion, we proposed the notion of joint exploration and development, which involves combining search strategy and operational approaches for a variety of oil resources in order to analyze, develop, acquire, and utilize numerous hydrocarbon sources at the same time. In this method, the vexing interference between the created mixture of hydrocarbon flow, which results in a reduction in single-well flowrate, might be transformed into a dynamic mutual force that boosts the well's flowrate. The necessity of joint exploration and development is dictated by the occurrence circumstances of oil and gas resources, its practicality is dependent on technological advancements, and its laborious and long-term nature is linked to the existing energy market and environment, we also point out. Despite a number of issues and challenges, we believe that collaborative exploration and development will be a viable choice for lowering costs and increasing output and benefits, boosting investor confidence, increasing energy comprehensive use, and improving energy supply efficiency. Keywords: development oil and gas resources, analysis, energy comprehensive use

Spatiotemporal Distribution of Precipitates and Mineral Phase Transition During Biomineralization Affect Porosity–Permeability Relationships

Enzymatically induced calcium carbonate precipitation is a promising geotechnique with the potential, for example, to seal leakage pathways in the subsurface or to stabilize soils. Precipitation of calcium carbonate in a porous medium reduces the porosity and, consequently, the permeability. With pseudo-2D microfluidic experiments, including pressure monitoring and, for visualization, optical microscopy and X-ray computed tomography, pore-space alterations were reliably related to corresponding hydraulic responses. The study comprises six experiments with two different pore structures, a simple, quasi-1D structure, and a 2D structure. Using a continuous injection strategy with either constant or step-wise reduced flow rates, we identified key mechanisms that significantly influence the relationship between porosity and permeability. In the quasi-1D structure, the location of precipitates is more relevant to the hydraulic response (pressure gradients) than the overall porosity change. In the quasi-2D structure, this is different, because flow can bypass locally clogged regions, thus leading to steadier porosity–permeability relationships. Moreover, in quasi-2D systems, during continuous injection, preferential flow paths can evolve and remain open. Classical porosity–permeability power-law relationships with constant exponents cannot adequately describe this phenomenon. We furthermore observed coexistence and transformation of different polymorphs of calcium carbonate, namely amorphous calcium carbonate, vaterite, and calcite and discuss their influence on the observed development of preferential flow paths. This has so far not been accounted for in the state-of-the-art approaches for porosity–permeability relationships during calcium carbonate precipitation in porous media.

Flow Characteristics of a Mixed Compression Hypersonic Intake

The flow field in a two-dimensional hypersonic mixed-compression inlet in a freestream Mach numbers of M∞ =2.0, 3.0, and 5.0 are numerically solved to understand the effect of throat area variation. The exit area ratio variation is simulated by placing a plug insert at different axial locations at the exit of the model. The flow field is achieved computationally by solving the Reynolds Averaged Navier-Stokes equations in a finite volume framework. For each flow condition, the variation in shock structure is analyzed and the variation of the oblique shock wave angle with the mass flow rate is calculated theoretically and compared with the present CFD analysis. The variation in oblique shock angle is calculated in terms of the mass flow rate by considering the capture area and spillage flow through the inlet. The theoretical results suggest that the method can predict the inlet operating conditions at different freestream Mach numbers and area ratios. This method can quantify the reduction in mass flow rate due to the throttling effect by analyzing the flow field shock pattern. The effects of various important performance parameters such as free stream Mach number, total pressure recovery, and mass flow ratio were then numerically investigated. As the Mach number is increased, the total pressure recovery is reduced, but the maximum value of the mass flow rate is increased. The analysis is also focused on the effect of throat area variation on performance parameters at each Mach number. The characteristic curve of the inlet is then obtained for each free stream Mach number.

Umbilical cord mesenchymal stem cells alleviate Sjögren's syndrome and related pulmonary inflammation through regulating Vγ4+ IL-17+ T cells.

BackgroundSince gamma delta (γδ) T cells are involved in various autoimmune diseases, we aimed to verify whether γδ T cells participate in the pathogenesis of Sjögren’s syndrome (SS) and related pulmonary inflammation, and also aimed to evaluate the effects of umbilical cord mesenchymal stem cells (MSCs) on SS-related pulmonary inflammation and the γδ T cells.MethodsThe saliva flow rates of female non-obese diabetic (NOD/Ltj) mice were measured. Histopathologic analysis was performed in salivary glands (SG) and lung tissues. The levels of γδ T cells and their subsets in the peripheral blood, spleen, and lung were examined by flow cytometry. The purified γδ T cells were adoptively transferred into NOD/Ltj mice. MSC transplantation was performed in 8-week-old NOD/Ltj mice.ResultsThe results showed lymphocytic infiltration in SG and lacrimal glands (LG), and reduction of saliva flow rates in 8-week NOD/Ltj mice. The levels of γδ T cells decreased in peripheral blood, but increased in the lung of 8- and 12-week-old NOD/Ltj mice. The proportions and numbers of Vγ4+ T cells and Vγ4+ IL-17A+ T cells increased in the lung, but decreased in peripheral blood of 8-week-old NOD/Ltj mice. Notably, transfer of γδ T cells decreased the rate of saliva flow, as well as aggravated the pathological changes in the lung. The transplantation of MSCs increased saliva flow rate and alleviated pathological injury in the SG and lung. The frequencies of Vγ4+ T cells and Vγ4+ IL-17A+ T cells in the lung and spleen significantly decreased after MSC treatment. Our results demonstrated that γδ T cells and Vγ4+ T cells contribute to the pathogenesis of SS and SS-related pulmonary inflammation. In addition, MSCs relieved SS and SS-related pulmonary inflammation through suppressing Vγ4+ IL-17A+ T cells.ConclusionsPeripheral Vγ4+ T cells infiltrate into the lung in SS mice, and aggravate the symptoms of SS and SS-related pulmonary inflammation by secreting IL-17A. Meanwhile, lymphocyte infiltration could be reversed by MSC transplantation, which indicates the potential of MSCs in the treatment of SS and SS-related pulmonary inflammation patients.

Phosphorus removal efficiency by in-stream constructed wetlands treating agricultural runoff: Influence of vegetation and design

With population growth, demand for agricultural products has increased, which affects agriculture, fertiliser use and land management. Due to nutrient inputs from arable areas, the water quality of rivers and lakes near agricultural lands has deteriorated. Constructed wetlands (CWs) are one of the measures used to improve water quality through natural water treatment processes. We studied phosphorus removal in relation to environmental characteristics in five in-stream free surface flow CWs in Finland, Estonia and Latvia. Wetland/catchment area ratios varied from 0.1% to 5%. Three CWs were covered in dense vegetation. On average, the Vända CW and Hovi CW TP removal efficiency throughout the study period were highest (32.1 ± 3.6% and 34.9 ± 4.4%, respectively) among all studied CWs. Nummela Gateway CW, Rantamo-Seitteli CW and Mezaciruli CW showed lower TP removal efficiency and on many occasions the outflow concentration exceeded the inflow concentration in Rantamo-Seitteli and Mezaciruli CW. Vegetation cover emerged as the most important factor in the treatment efficiency of in-stream CWs, reducing flow rate, increasing water retention time and decreasing probability of the CW becoming a source of phosphorus during flood events.

A novel type of unpowered air curtain at a tunnel portal to reduce the intrusion of cold air

In modern cities in cold regions, where the average ambient temperature is always below 0 °C during winter, an increasing number of subway lines are being constructed due to the rapid development of urban traffic. Cold air intrusion is caused by train operation, and natural ventilation will pose a risk of freezing equipment at the tunnel entrance and affect the regular operation of the subway line. However, there is still a lack of established efficient and energy-saving methods to control the cold air invasion of tunnels. In this paper, a new curved tunnel structure installed at the entrance of a tunnel can form an unpowered air curtain, and the installation method and optimal structure of the curved tunnel are determined by numerical simulation. In this research, by optimizing the four dimensionless geometric parameters of the curved tunnel structure, a primary optimized structure with a flow reduction rate of 18.79% is obtained. In addition, the flow reduction rate of the curved tunnel can be increased to 37.29% by adding a deflector at the curved tunnel entrance. The optimized results are verified by a scale model experiment, ensuring the accuracy of the proposed structure. This paper provides guidance for the study of controlling cold air invasion at tunnel portals.

Identifying the performance and losses of a scroll compressor with vapour injection and R1234ze(E)

This work investigates a vapour injection scroll compressor integrated in a heat pump using the refrigerant R1234ze(E). The water-to-water heat pump was tested under a wide temperature range at the evaporator and condenser sides. The test results revealed that the performance is significantly reduced for lifts of over 30 K with the coefficient of performance being even below 2 and the maximum 2nd law efficiency was just 28%. In order to enlighten the reasons behind such significant compressor underperformance, a semi-empirical model has been extended to include vapour injection, and a new improved modelling approach for the suction pressure drop was developed and implemented considering both the turbulent and laminar inlet flow regimes. Once the accuracy of the developed semi-empirical model was verified, the model was then adjusted to account for the R1234ze(E) operation, by fine-tuning its parameters based on the test data. The main loss mechanism identified is the high suction pressure drop, due to the high friction factor, with the inlet refrigerant flow possibly being laminar instead of turbulent. This resulted in a significant reduction of the mass flow rate and volumetric efficiency, while the standard model for suction pressure drop was not able to capture this effect.

Experimental Analysis of Evacuation Pressure and Gas Flow Rate in Structured-Core Transparent Vacuum Insulation Panels

The notion that modern buildings should strive to be net zero energy buildings (NZEBs) is widely accepted. One of the causes leading to high energy usage for space heating, resulting in avoidable carbon emissions, is heat loss via building windows. In order to improve window’s insulation in existing buildings, structured-core transparent vacuum insulation panels (TVIPs) are proposed. TVIPs mainly consist of the structured core material, the low-emissivity film, and the transparent gas barrier envelope. TVIPs have high insulation performance and are inexpensive to manufacture and can be easily installed. Therefore, TVIPs have potential to improve window’s insulation in existing buildings with low cost. However, it is necessary to overcome the issue of preventing the pressure rise inside TVIP after vacuum sealing. The authors constructed an experimental setup to quantify the effect of reduction of gas flow rate in TVIP after evacuation by applying pressure-rate-of-rise-method. In this experiment, a gas barrier film with a straw was used as the vacuum chamber. This could reproduce the pressure increase in the TVIP after sealing and the gas flow rate in the TVIP is evaluated. The experimental result show that the coated core material and the enclosing getter agentlowered the pressure rise and gas flow rate in TVIP by combining concurrent evacuation and heating. Furthermore, after extending the simultaneous vacuuming and heating period to 8 hours and applying the coated core material and enclosing the gettering agent, the internal pressure in TVIP may be lowered to around 1 Pa after 30 minutes after halting vacuuming. It was confirmed that this pressure satisfied the performance required for TVIPs, and the result was much closer to the realization of TVIPs.

Suppression of flow pulsations and energy consumption of a drug delivery roller pump based on a novel tube design

A drug infusion peristaltic pump is experimentally studied, examining its performance for three flexible tubes, two cylindrical, and an innovative one of lenticular cross-section with an inflated part. Using water as flowing medium, the pump outlet flow rates were measured at nine phases of the semi-period, based on phase-locked 2D-PIV data. The roller disengagement phase showed to cause a reduction of the outlet flow rate, and in a lesser degree, the engagement phase. Flow acceleration at the pump outlet occurred when only one roller was squeezing the tube. The gauge pressure waveforms at the pump inlet and outlet although noisy had a phase lead with respect to the flow rate. According to the pump motor current waveform, the work of the forces necessary for the tube deformation was about 10 times higher than that of the fluid viscous and inertial forces. Among the three examined flexible tubes, the pump performance was the best when the lenticular tube was used, presenting the highest volumetric efficiency and the smallest outlet flow rate pulsations, pressure amplitudes, and energy consumption. The high pump performance is attributed to the innovative inflated part of the lenticular tube, its cross-sectional shape and its higher compliance compared to the other tubes.

A Rare Cause of Severe Biventricular Dyssynchrony During Venoarterial Extracorporeal Membrane Oxygenation for COVID-19 Respiratory Failure

A Rare Cause of Severe Biventricular Dyssynchrony During Venoarterial Extracorporeal Membrane Oxygenation for COVID-19 Respiratory Failure

Combating district heating bottlenecks using load control

The 4th generation of district heating systems face a potential problem where lowered water temperatures lead to higher flow rates, which requires higher hydraulic capacity in terms of pipe and pump sizes. This increases the effect of the already existing issue of hydraulic bottlenecks, causing peripheral units (customers) to experience reduced flow rates. A coordinating control strategy is presented in this work aimed at reducing the effect of such bottlenecks on the comfort of customers. This is done by distributing the flow deficit over many units rather than a few. Previous works mainly focus on MPC-structured controllers that depend on complex system models and online optimization techniques. This work proposes a method that requires little information about models for individual units and minimal IT communication between control systems. The proposed method is compared with a traditional control strategy and an optimal baseline in a simulation study. This shows that the proposed method can decrease the worst case indoor temperature deviations.

Hepatorenal syndrome: criteria and problems of diagnosis (part II)

Hepatorenal syndrome, the extreme manifestation of renal impairment in patients with cirrhosis, is characterized by reduction in renal blood flow and glomerular filtration rate. Hepatorenal syndrome is diagnosed when kidney function is reduced but evidence of intrinsic kidney disease is absent. Unlike other causes of kidney injury, hepatorenal syndrome results from functional changes in the renal circulation and is potentially reversible. An analysis of literature reviews, clinical studies, experimental research, clinical recommendations from PubMed / Medline and ELIBRARY databases was carried out for 7 keywords according to the review topic.

Stormwater runoff reduction benefits of distributed curbside infiltration devices in an urban catchment

Distributed infiltration systems can benefit downstream water bodies by reducing the runoff flowrate and volume discharges from the catchment. Investigating their runoff flowrate and volume reduction potential at the catchment scale will inform decision makers regarding their efficacy for managing catchment outflows. To this end, we conducted field investigations at the residential catchment scale for three years. The study monitored the catchment for one year before the installation of leaky well systems (preinstallation) and two years after installation (postinstallation). The hydrological model, calibrated to preinstallation catchment outflows, acted as a virtual control tool. Runoff flow outputs from the control model and two years of monitored runoff flow data from the postinstallation period were analysed using statistical methods. The statistical tests showed a significant 13% reduction in average flowrates in storms with a corresponding runoff flowrate of up to 50 L/s. The study further reported the ability of infiltration systems to reduce runoff volume in the catchment by 9%. This reduction was not significant, however, as per the results of the statistical analysis. We then fitted the generalized linear model (GLM) to the monitored and simulated runoff volume data. This enabled us to break down the effect of curbside infiltration systems on runoff volume according to corresponding peak flowrates during the storm. The results of the two-way ANOVA performed to detect significant differences in the regression slopes of the GLM indicated that curbside infiltration systems significantly reduced runoff volume for storms when the runoff flowrates remained below 100 L/s.

Validation of the thermal-hydraulic thunder code and application for PWR core in transient conditions

The THUNDER computer code allows performing thermal-hydraulic core analysis of pressurized water reactors aiming at the design and safety analysis of power and naval reactors in steady state and transient conditions. It uses the subchannel and control volume methods to perform a tridimensional analysis of the nuclear reactor core. The conservation equations are solved simultaneously for each control volume based on geometric and operation conditions. The Integral Momentum Method is used for solving the conservation equations decoupling the momentum equation from the mass and energy conservation equations. The drift-flux model is adopted to treat the two-phase flow condition. The analysis is performed in two-stages: first, a macroscopic analysis is conducted with subchannel equivalent to a fuel assembly (bundle), and second, with a subchannel equivalent to an individual coolant channel. Only the hottest fuel assembly is analyzed with detail. To validate the THUNDER code we used the experimental data from the NUPEC PWR benchmark (subchannel and bundle tests), in which we verify the accuracy of the coolant temperature at steady-state in 4 different void fraction conditions and the accuracy of the void fraction at transients initiated by four different conditions: core power increase, reduction of inlet mass flow rate, increase of inlet coolant temperature and depressurization of the inlet coolant. At steady-state conditions, the mean relative discrepancy for the coolant temperature was 0.09. At transient conditions, the void fraction mean absolute discrepancy for power increase was 0.045, for mass flow reduction was 0.079, for inlet coolant depressurization was 0.032 and for temperature increase was 0.092. The code was applied for the Brazilian 1350 MW nuclear power plant ANGRA 2 for evaluating the thermal-hydraulic safety parameters at steady-state, as well as the operational transients of loss of one or several primary coolant pumps. The THUNDER code results showed that the safety limits were not exceeded in concordance to the Final Safety Analysis Report of the plant. These results indicate that the THUNDER code is sufficiently accurate to perform thermal-hydraulic analyses for PWR power plants at steady-state and transient conditions.

Couette flow in a rectangular channel in the whole range of the gas rarefaction

The mass flow rate of a Couette flow in a long rectangular channel is calculated for constant or linear wall velocities in the whole range of the gas rarefaction and in a wide range of the width-to-height ratio. Analytical solutions for arbitrary width-to-height ratios are given for the hydrodynamic regime, the slip regime, and the free molecular regime. Therefore, both the velocity field and the mass flow rate can be calculated. In the transitional regime, simulations via direct simulation Monte Carlo method are performed. The results are provided as reduced flow rates in tabulated data, which can be used for any constant or linear increasing wall velocity (e.g., bounding walls of working chambers in positive displacement vacuum pumps).

Contemporary outcomes of precision banding for high flow hemodialysis access.

High-flow hemodialysis accesses are a well-recognized source of patient morbidity. Among available management strategies inflow constriction based on real-time physiologic flow monitoring offers a technically straightforward data-driven approach with potentially low morbidity. Despite the benefits offered by this approach, large contemporary series are lacking. A retrospective review of a prospectively maintained clinical database was undertaken to capture patients undergoing precision banding within a signal tertiary care institution between 2010 and 2019. Multivariable logistic regression modeling of thrombosis within 30 days and re-banding within 1 year were performed. In total, 297 patients underwent banding during the study period for a total number of 398 encounters. Median [IQR] follow-up was 157 [52-373] days. Most accesses were upper arm with brachial artery inflow (84%) and half of the banding procedures were performed for flow imbalance based on exam, duplex, or fistulogram. Median flow rate reduction was 58%. The 30-day thrombosis rate after banding was 15 of 397 (3.8%) with a median time to event of 5.5 days (2-102). The re-banding rate within a year was 54 of 398 (14%) with a median time to re-banding of 134 days [56-224]. Multivariate logistic regression analysis using a univariate screen did not identify any predictors of 30-day thrombosis. Having a forearm radial-cephalic AVF compared to all other access types was protective against need for rebanding at 1 year (OR 0.12 95% CI 0.02-0.92, p = 0.04), as was flow imbalance as the indication for banding (OR 0.43 95% 0.23-0.79, p = 0.006). Precision banding offers an effective, low-morbidity approach for high-flow hemodialysis accesses. Early thrombosis is a rare event after precision banding, although in the long term, one in four patients will require re-banding to maintain control of flow volumes.

Pressure behavior and heat transfer behavior of air natural convection in an asymmetrically heated vertical channel with a damper

The natural convection of air between vertical parallel plates under asymmetrical heating was investigated focusing on the pressure behavior and the heat transfer performance as varying two experimentally controlled parameters, namely, the damper closing angle (0 ∼ 45 °) and the thermal operating condition (1.7 ∼ 6.4 kW). By varying the damper closing angle, the form loss coefficient of the damper was estimated from the measured pressure and the calculated pressure difference relating to the thermal gravity effect. It was verified that the form loss coefficient estimated for natural convection was close to the reported form loss coefficient estimated for forced flow. The thermal stratification of the ambient air was additionally considered in the pressure analysis. In addition, the heat transfer was analyzed in terms of the heat transfer correlation. As the damper angle increased, the heat transfer performance decreased owing the reduced flow rate. However, as the thermal operating condition intensified, the heat transfer performance was increased by the improved flow rate. Interestingly, the trend of the Rayleigh number was the same regardless of the two control parameters, even though an intensifying thermal boundary condition improved the heat transfer performance and an increasing damper closing angle weakened the heat transfer performance, conflictingly. Therefore, the correlation conventionally used for natural convection cannot be applied under the conditions of a high wall temperature and control using a damper because it does not consider the flow rate effect. To consider the flow rate effect additionally in the heat transfer correlation, a correlation based on Jackson's mixed convection correlation is suggested. The suggested correlation predicts the heat transfer performance on each wall by considering the effects of the damper angle and operating condition, simultaneously, within the error of less than 30%.

Non-equilibrium molecular dynamics simulation to evaluate the effect of confinement on fluid flow in silica nanopores

The flow of fluids in nano-confinement has applications in separations, water purification, medical systems and in the recovery of fluids in petroleum systems. It is believed that fluids do not obey continuum laws when flowing in nanopores (or in confinement). This paper attempts to shed light on various nano confinement effects such as fluid-wall interactions, pore size and molecular geometry, using molecular dynamic simulation. Water, hexane, and methanol flow behaviors were simulated for pore diameters ranging from 1 to 8 nm. In addition to the density analysis of the confined fluids, the fluid flows in saturated nanopores were simulated by the sectional flow method. Water and methanol molecules were completely stabilized in the 1 nm pore. Hexane molecules could not enter the 1 nm pore, due to geometric considerations. For the 2 – 8 nm pores, all fluids showed reduced flow rate compared to the Hagen–Poiseuille flow, due to an interfacial molecular layer stabilized at the pore surface. Flow reduction observed in these studies is contrary to significant flow enhancements observed for fluid flow in carbon nanotubes of similar dimensions. Water flow showed almost constant stick length for all the pore sizes. Methanol flow had the largest stick length. Hexane flow was reduced because of overcrowding of molecules at the pore surface. The effect of confinement diminished with an increase in pore diameter.