Average Flow Volume Research Articles

Streamflow Simulation for Nam Xong River Basin in Vang Vieng District, Vientiane Province

Nam Xong River is one of the tributaries of Nam Lik River, which is considered an important river that creates natural tourism value for the people in Vang Vieng District. Nam Xong Dam was another dam built to generate electricity and divert water to Nam Ngum 1 reservoir to increase hydropower generation capacity. Recently, Nam Xong River Basin (NXRB) has been affected by flooding almost every year due to changes in the amount and pattern of rainfall which is highly variable. Another issue is aggravated by the problem of ungauged basins where the number of hydrological and meteorological stations are limited and unequally distributed over the basins. This obstructs the reliability of streamflow prediction and water resources management. This study therefore aims to address the problems of ungauged basins by performing tasks that serve a main objective: application of HEC-HMS for simulating the streamflow for NXRB. The hydrological and meteorological data used in this study are daily streamflow 2 stations and rainfall 4 stations located in and around the basin. The simulation period is considered based on random flood events from 2005 to 2021. Out of these, 5 events (2005-2015) are selected for model calibration and another event of 2021 are considered for model validation. The results found that the HEC-HMS model can estimate the flow rate in accordance with the observed data, especially during the low flow period. Throughout the considered period, the average flow and total flow volume showed a downward trend. For the result of estimating the maximum flow from the model, the streamflow is lower than the observed data, and the time to peak from the model comes about 1 day later than the observed one in 2014, probably due to the distribution of rainfall in the study area with high variability. Therefore, the HEC-HMS model could be used to simulate daily streamflow in limited data areas. This study could provide recommendations for hydrological modeling for other basins that have similar characteristics to the NXRB.

Study on the Water Use at the Tailwater of Nam Theun 2 Hydropower Station through the Canal of the 3rd Water Gate (Case study: Nongping and Boungbao villages) Nhommalath District, Khammounce Province

Water management is managed through the Nam Theun 2 hydroelectric project. The project has released water in two parts: 1) Water gates and channels release water into natural streams about 30 km long and can drain 1,200 m3/s; and 2) Releasing through the newly constructed regulating dam to the Xe Bang Fai River directly, with a length of about 27 km, can drain 330 m3/s. According to the length of the channel, there is a built water gate for 5 irrigations. Currently, only 3 water gates have been opened to supply water for production in 9 villages that depend on Nhommalath district, Khammouane province. In order to make the use of water through the channel to the maximum benefit, it can operate together between electricity generation and the actual use of water by the community. In this chapter, we have studied the amount of water flow according to the season through Regulating Dam during the past 11 years. Since 2012 to 2022, we have studied the participation of farmers in the management and use of water within the scope of agricultural land. Through comparing the amount of water flow during the past 11 years, from 2012 to 2022, The amount of water flow through the channel with the lowest flow in December 2022 is equal to 0.0 cubic meters per second caused by the stoppage of the company's electricity production to do various repairs, and the highest flow rate in November 2016 was 318.18 cubic meters per second. The reason is that the project has full production capacity to respond to the electricity buyers. Among them, the annual average flow volume with the lowest value in 2022 is equal to 153.06 cubic meters per second, and the annual average flow volume with the highest value in 2017 is equal to 239.11 cubic meters per second. At the time the company stopped production, it used a backup pump with a suction power equal to 0.083 m3/s, which was installed at 2 points to pump water into the irrigation channel for the people. The company is responsible for all costs, such as fuel for the pump, maintenance of the pump, and the water system from the pump to the channel. Assessment of farmers' participation in water management with topics such as survey participation and data collection, participation in the implementation of four seasonal plans, participation in monitoring and evaluation, and participation in the review of all outputs is at a very satisfactory level ( = 3-3.8), except for the topic of participation in determining water use regulations within the channel, and the flood problems are evaluated at a moderate level ( = 2.4). Because of management, the municipality has appointed a committee and has specific management rules. There has never been a natural disaster in the area in the past, such as a drought or flood.

Spatio-Temporal Distribution of Water Availability in Marshyangdi Basin: Hydrological Model Development

This Study has developed a hydrological model for the Marshyangdi river basin in Western Nepal, showing considerable potential for developing water resources and overall national prosperity. The model is also used to characterise hydrology and assess the availability of water resources across different spatial and temporal dimensions, hence improving our comprehension of water availability and its possible applications. The newly developed hydrological model in the Soil and Water Assessment Tool (SWAT) replicates the mean flows, hydrological pattern, and flow duration curve at the basin and 54 sub-basin outputs. Additionally, the model undergoes calibration and validation, employing Sufi-2 to fine-tune hydrological parameters. Based on the data generated by the model, the annual average precipitation (P) in the Marshyangdi basin is projected to be 1843 mm. Approximately 17.88% of the average yearly rainfall is lost via evapotranspiration; however, this varies significantly across different locations and time periods. Contrasting the two, the mountains have a higher moisture level than the Himalayan regions. The predicted average annual flow volume at the basin outflow is 9467.423 million cubic metres (MCM). Examining water shortages, finding regions with excess water, and developing solutions to address the competing needs of agriculture, industry, urban areas, and ecosystems are advantageous. Therefore, this method may improve the effectiveness of strategic planning and the long-term management of water resources.

Sustainable bio-inspired water pump using a thermo-pneumatic phenomenon with a blinking light

In the natural world, the irradiance intensity of sunlight on the ground changes periodically due to diurnal motion. Here, inspired by natural trees, we propose a water pump using a thermo-pneumatic phenomenon with a blinking light. Specifically, we demonstrate that by the periodic irradiation of 110 W/m2 for the intrinsic irradiation area of ∼15 cm2, a Y-shaped bio-inspired pump having three chambers with two check valves can suck up water from a water source and expel it from the outlet at a 30 cm height with an average volume flow rate of ∼2.1 cm3/h (∼0.7 cm3/cycle). Surprisingly, the pumping ability of our pump is ∼20.4 times higher than that of the recent high-performance artificial tree in a simple comparison. Our findings should contribute to the sustainable transport of water and understanding of the transportation mechanism of natural trees in the future.

Analysis of hemodynamic changes in vertebral arteries and veins during functional tests with ultrasound monitoring

Aim to evaluate the correlation between the course of vertebral arteries and veins and the results of calculations of hemodynamic parameters during ultrasound with functional tests.
 Material and methods. In the observation, 252 volunteers were examined using Samsung SonoAce R7 and GE Logiq F6 equipment. The hemodynamics was studied at the level of the second segment of the vertebral arteries and veins at rest, when turning, tilting and lifting the head. The results were processed using Microsoft Excel 2007 with subsequent statistical analysis.
 Results. 504 vascular complexes were analyzed without taking into account the visualization side. When assessing the arteries, the highest maximum blood flow velocity was registered when lifting the head in women with a rectilinear course of the vessels. In the group of men with non-rectilinear course of vessels, the lowest average blood flow velocity was registered when tilting the head. The highest volume flow was recorded in case of non-rectilinear vascular course in women when lifting the head.
 For vertebral veins, the highest indicators of maximum and minimum venous blood flow rates were observed in men with a rectilinear course of vessels when lifting the head. The highest values of the average flow velocity and volume flow were noted in men who had a rectilinear course of the vessels.
 The maximum values of the calculated venous volume flow were registered in groups with rectilinear vascular course: in men up to 19.4214.85 ml/min. (Me 12.45 ml/min.), in women 18.52 15.30 ml/min. (Me 10.50 ml/min.).
 Conclusion. The data obtained by the study contributes to improving the software and analysis of individual changes during patient examination, helps to evaluate the effectiveness of treatment and rehabilitation, as well as to analyze multifactorial models.

Predictors of Arteriovenous Fistula Maturation among Patients with Severe Obesity

There is an increasing prevalence of obesity among patients who develop end-stage renal disease and require dialysis. While referrals for arteriovenous fistulas (AVFs) among patients with class 2-3 obesity (i.e., body mass index [BMI] ≥ 35) are increasing, it is unclear what type of autogenous access is most likely to mature in this patient population. This study was designed to evaluate factors that impact maturation of AVF among patients with class ≥2 obesity. We retrospectively reviewed AVFs created at a single center from 2016 to 2019 for patients who had undergone dialysis within the same healthcare system. Ultrasound studies were used to evaluate factors that defined functional maturation, including diameter, depth, and volume flow rates through the fistula. Logistic regression models were used to evaluate the risk-adjusted association between class ≥2 obesity and functional maturation. A total of 202 AVFs [radiocephalic (24%), brachiocephalic (43%), and transposed brachiobasilic (33%)] were created during the study period, of which 53 (26%) patients had a BMI >35. Functional maturation was significantly lower among patients with class ≥2 obesity undergoing brachiocephalic (58% obese versus 82% normal-overweight; P=0.017), but not radiocephalic or brachiobasilic AVFs. This was primarily a result of excessive AVF depth in severely obese patients (9.6±4.0mm obese versus 6.0±2.7mm normal-overweight; P<0.001), whereas there was no significant difference found in average volume flow or AVF diameter between groups. In risk-adjusted models, a BMI ≥35 was associated with a significantly lower likelihood of achieving AVF functional maturation (odds ratio: 0.38; 95% confidence interval: 0.18-0.78; P=0.009) after controlling for age, sex, socioeconomic status, and fistula type. Patients with a BMI >35 are less likely to mature AVFs after creation. This principally affects brachiocephalic AVFs and occurs because of increased fistula depth as opposed to diameter or volume flow parameters. These data can help guide decision-making when planning AVF placement in severely obese patients.

Biological analysis of emerging nanoparticles with blood through propagating flow along a plumb porous canal in the occurrence of energy and heat transfer

This paper presents the study of unsteady peristaltic flow across a channel with finite width and porous medium. Here, we have discussed the effects of nanoparticles on blood through a vertical porous sinusoidal channel with radiation and heat generation/ absorption cases. This work has not been yet discussed in literature. The aim of the present study is to see the effects of nano particles with blood in Esophagus to see its application in drug delivery and biomedical engineering etc. It also has many applications in microscale phenomena in physiology. Here blood is taken as a base fluid and nanofluid is prepared by the suspension of copper oxide nanoparticles in blood. Copper oxide is extremely useful in the medical domain for drug delivery and cancer treatment. In a restricted domain, the proceeding equations for temperature, transverse velocity, pressure gradient, axial velocity, volume flow rate, shear stresses at walls, average volume flow and stream function were solved. By plotting the graphs of temperature profile, velocity profile, wall shear stress, reflux limit, and stream lines, the effect of different parameters has been analyzed.

Generation of a net flow due to fixed oblique beam structures in the nucleate boiling region

Effective utilization of unused heat below 200 °C is essential for a sustainable society. In this study, we propose a thermally driven water pump using fixed oblique beam structures with bubbles in the nucleate boiling region (approximately, 100–130 °C). Here, the oblique beam structure breaks the symmetry of the bubble force, and thus, they provide a net flow. Specifically, by using six fixed oblique beams along a circular fluidic channel, we observed a net flow of an average flow velocity of ∼40 mm/s and an average volume flow rate of ∼10 000 mm3/s (∼0.01 l/s) at the superheat of ∼22 K. Our findings should contribute to the effective use of unused heat such as factory waste heat and environmental energy.

Fetal 4D flow MRI of the great thoracic vessels at 3 Tesla using Doppler-ultrasound gating: a feasibility study

ObjectivesTo evaluate the feasibility of Doppler-ultrasound (DUS)-gated 4D flow MRI of the fetal great thoracic vessels at 3T in a clinical setting.MethodsSixteen consecutive fetuses (range 30+4–38+5 weeks) with (n = 11) and without (n = 5) cardiovascular anomalies underwent 4D flow MRI of the great thoracic vessels at 3T. Direct fetal cardiac gating was obtained using a MR-compatible DUS device. 4D flow MRI–based visualisation and quantification of four target regions (ascending aorta (AAo), descending aorta (DAo), main pulmonary artery (MPA), and ductus arteriosus (DA)) were performed using dedicated software.ResultsFetal 4D flow MRI of the great thoracic vessels was successful in 12/16 fetuses (75%) by adopting clinical 4D flow MR protocols in combination with direct fetal cardiac DUS-gating. Four datasets were excluded due to artefacts by fetal movement or maternal breathing. 4D flow MRI–derived time-velocity curves revealed typical arterial blood flow patterns in the aorta. 4D flow quantification was achieved for the pre-defined target regions. Average velocity and flow volume were 21.1 ± 5.2 cm/s and 6.0 ± 3.1 mL/s in the AAo, 24.3 ± 6.7 cm/s and 8.4 ± 3.7 mL/s in the DAo, 21.9 ± 6.4 cm/s and 7.8 ± 4.2 mL/s in the MPA, and 23.4 ± 4.7 cm/s and 5.9 ± 3.6 mL/s in the DA, respectively.ConclusionsCombination of DUS-gating of the fetal heart and 4D flow MRI allows comprehensive visualisation and quantification of haemodynamics in the fetal great thoracic vessels. DUS-gated fetal 4D flow MRI may provide a new diagnostic approach for prenatal assessment of blood flow haemodynamics.Key Points• Fetal cardiac Doppler-ultrasound (DUS) gating and 4D flow MRI can be successfully combined.• DUS-gated fetal 4D flow MRI allowed visualisation and evaluation of streamline directionality, illustration of blood flow variations, and pulsatile arterial waveforms in the target vessels.• 4D flow MRI–based visualisation and quantification of the fetal great thoracic vessels were successful and flow metrics agreed with echocardiographic reference values.

Profile Design and Performance Research of Hydrogen Circulation Pump in Fuel Cell System

A general design formula for rotor profile is proposed based on conjugation theory and feasibly verified by using the four different design shapes. The overset mesh method and the realizable k-ε two-layer turbulence model are used for simulation calculation. The results stated that the average volume flow error of hydrogen medium and air medium is small, so an alternative experimental study has been carried out. By building a test system for experimental verification, it is found that the error between the simulation results and the experimental results is small at the low-pressure ratio and increases at the high-pressure ratio because the influence of the ambient temperature is not considered. The results further verified the reliability using the simulation calculation method. At last, the fluid characteristics of the two-tangent-arcs type, single-arc type, ellipse type, and quadratic-curve type rotors are evaluated. The result shows that the comprehensive performance of the single-arc type rotor is superlative as followed by the ellipse type rotor. However, the quadratic-curve rotor has the largest average flow but the worst flow stability and the two-tangent-arcs rotor shows the smallest average flow.

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.

Chiari Type 1 malformation: CSF flow dynamics and morphology in the posterior fossa and craniocervical junction and correlation of these findings with syrinx formation

BackgroundChiari type 1 malformation (CMI) is a disorder in which cerebellar tonsils descend below the foramen magnum. Although syringomyelia associated with CMI thought to be caused by hypoplastic posterior fossa and stenosis at the craniocervical junction; it has characteristic neurological and radiological features and the exact mechanism of syringomyelia remains unknown. PurposeThe purposes of this study were to gain insight into morphological changes in posterior fossa and to find whether there is a difference in aqueductal stroke volume (ASV) between CMI with syrinx and without syrinx which may be an underlying mechanism of syrinx development. Materials and methodsWe consecutively evaluated 85 patients with Chiari malformation between January 2017 and December 2019 who had undergone phase-contrast MRI examination for CSF flow and between 18–60-years-old. We divided patients into two groups as subjects with syrinx (n=19) and without syrinx (n=66). After evaluating morphological changes, peak and average velocity (cm/s), forward and reverse flow volume (μl), net forward flow volume (μl), ASV (aqueductal stroke volume) (μl), aqueductus Sylvi (AS) area (mm2), and prepontine cistern diameter to AS diameter ratio (PPC/AS) were calculated. Distribution of variables from two groups was evaluated by using Shapiro–Wilk normality test. Independent t test was used for groups comparison. ResultsThe forward and reverse volumes were statistically significantly higher in patients with syrinx (P=0.021, P=0.005 respectively). ASV was significantly increased in patients with syringomyelia (P=0.014). The PPC/AS was significantly lower in patients with syrinx compared to those without (P <0.001). AS area was significantly larger in those with syrinx. (P=0.022). The diameter of foramen magnum was significantly lower in patients with syrinx than those without (P <0.0001). The diameter of the herniated tonsilla at the foramen magnum level was found to be significantly lower in those with syrinx (P=0.011). ConclusionForamen magnum diameter, ASV, diameter of herniated tonsil, and PPC/AS ratio are important factors in syrinx development.

Non-Invasive Evaluation of Cerebral Hemodynamic Changes After Surgery in Adult Patients With Moyamoya Using 2D Phase-Contrast and Intravoxel Incoherent Motion MRI.

ObjectiveTo explore the feasibility of 2D phase-contrast MRI (PC-MRI) and intravoxel incoherent motion (IVIM) MRI to assess cerebrovascular hemodynamic changes after surgery in adult patients with moyamoya disease (MMD).MethodsIn total, 33 patients with MMD who underwent 2D PC-MRI and IVIM examinations before and after surgery were enrolled. Postsurgical changes in peak and average velocities, average flow, forward volume, and the area of superficial temporal (STA), internal carotid (ICA), external carotid (ECA), and vertebral (VA) arteries were evaluated. The microvascular perfusion status was compared between the hemorrhage and non-hemorrhage groups.ResultsThe peak velocity, average flow, forward volume, area of both the ipsilateral STA and ECA, and average velocity of the ipsilateral STA were increased (p < 0.05). The average flow and forward volume of both the ipsilateral ICA and VA and the area of the ipsilateral VA were increased (p < 0.05). The peak velocity, average velocity, average flow and forward volume of the contralateral STA, and the area of the contralateral ICA and ECA were also increased (p < 0.05), whereas the area of the contralateral VA was decreased (p < 0.05). The rf value of the ipsilateral anterior cerebral artery (ACA) supply area was increased (p < 0.05) and more obvious in the non-hemorrhage group (p < 0.05).ConclusionTwo-dimensional PC-MRI and IVIM may have the potential to non-invasively evaluate cerebrovascular hemodynamic changes after surgery in patients with MMD. An improvement in the microvascular perfusion status is more obvious in patients with ischemic MMD than in patients with hemorrhagic MMD.

Experimental Regulating Parameters of Bladder-Type Hydraulic Accumulator

Experimental regulating parameters of the non-stationary expansion of air inside a bladder-type hydraulic accumulator, working with the simple short pipeline, are presented in the paper. The technique of continuous online monitoring of changes in time of volume and absolute air pressure inside the hydraulic accumulator during the discharge process has been improved. Three series of experimental studies of transient gas processes inside the accumulator at different values of the average volume flow rate are made. Tendencies of change of the integral parameters of the hydraulic accumulator are obtained and analyzed depending on the serial number of the discharge cycle. A general dependence of dimensionless storage volume &lt;i&gt;Kreg&lt;/i&gt; on the polytropic index &lt;i&gt;n&lt;/i&gt; in series # 1–3, approximated by single power-law dependence, is obtained. The systematic changes of integral parameters in each subsequent discharge cycle can be explained by the non-stationary transient thermodynamic processes in air inside the accumulator until the thermodynamic equilibrium with the ambient air parameters is reached.

Methodologies towards approximating the volume displacement by a roller in a roller-type peristaltic pump

The roller volume displacement (RVD) is the volume that a roller displaces within the tube of a roller-type peristaltic pump when it is being occluded by the roller, not to be confused with the pump volume displacement. The RVD is generally measured in order to model and simulate the pump by means of first principle modeling. The rate of change of this volume displacement (referred to as the roller induced flow rate) gives rise to the pulsatile flow rate and pressure commonly associated with roller-type peristaltic pumps. In addition to this, the volume displaced by the roller reduces the amount of transported fluid per revolution of the motor, effectively altering the average volume flow rate of the pump. The ability to obtain this flow rate without physically measuring it is advantageous for both design and modeling applications. This paper provides methods of approximating the volume displaced by the roller in a roller-type peristaltic pump. The approximations are derived from the pump and process tube dimensions. Several methods of varying complexity and accuracy are provided for approximating the maximum volume displaced by the roller. An angle dependent approximation allows for approximating this volume for both partial occlusion and compressed occlusion of the tube. The approximations are validated by testing the RVD of a roller-type peristaltic pump with specified geometries. Validation is achieved by means of measuring the RVD of the physical pump, as well as pump volume displacement over various motor speeds and comparing these values to modeled values. Additionally, the variable occlusion approximation is used to simulate the pressure response of the pump’s inlet and outlet and compared to the same simulation using the measured RVD. The variable occlusion approximation was found to have a normalized root-mean square error (NRMSE) of 6.09% when compared to the experimental average over the entire angle of engagement. Comparing the approximated RVD simulation results to that of the measured RVD simulation results revealed an average NRMSE of 6.35% and 6.62% for the inlet and outlet pressures respectively for the entire span of simulated motor speeds.

Decreased CSF Dynamics in Treatment-Naive Patients with Essential Hypertension: A Study with Phase-Contrast Cine MR Imaging.

Arterial sclerosis resulting from hypertension slows CSF transportation in the perivascular spaces, showing the intrinsic relationship between the CSF and the blood vasculature. However, the exact effect of hypertension on human CSF flow dynamics remains unclear. The present study aimed to evaluate CSF flow dynamics in treatment-naive patients with essential hypertension using phase-contrast cine MR imaging. The study included 60 never-treated patients with essential hypertension and 60 subjects without symptomatic atherosclerosis. CSF flow parameters, such as forward flow volume, forward peak velocity, reverse flow volume, reverse peak velocity, average flow, and net flow volume, were measured with phase-contrast cine MR imaging. Differences between the 2 groups were assessed to determine the independent determinants of these CSF flow parameters. Forward flow volume, forward peak velocity, reverse flow volume, reverse peak velocity, and average flow in the patients with hypertension significantly decreased (all, P < .05). Increasing systolic blood pressure was significantly associated with lower forward flow volume (β = -0.44 mL/mL/mm Hg; 95% CI, -0.83 to -0.06 mL/mL/mm Hg), forward peak velocity (β = -0.50 cm/s/mm Hg; 95% CI, -0.88 to -0.12 cm/s/mm Hg), reverse flow volume (β = -0.61 mL/mL/mm Hg; 95% CI, -0.97 to -0.26 mL/mL/mm Hg), reverse peak velocity (β = -0.55 cm/s/mm Hg; 95% CI, -0.91-0.18 cm/s/mm Hg), and average flow (β = -0.50 mL/min/mm Hg; 95% CI, -0.93 to -0.08 mL/min/mm Hg). The CSF flow dynamics in patients with hypertension are decreased, and increasing systolic blood pressure is strongly associated with lower CSF flow dynamics.

Evolution and control of deformation mechanisms in micro-grooving of Zr-based metallic glass

The evolution of deformation mechanisms with increasing depth of cut (DOC) in micro-grooving of Zr-based metallic glass was deeply investigated in this study for the first time. The micro-grooving characteristics of metallic glass were initially studied by nanoscratch test, which verified that the material removal mode abruptly changes from extrusion mode to cutting mode with increase of DOC. Based on the free-volume theory, a dynamic model coupling stress, temperature and free volume concentration was used to simulate the change of deformation characteristics with DOC. The results showed that the deformation mechanism of metallic glass is closely related to free volume flow, which is significantly affected by average strain rate and free volume flow coefficient in deformation zone and can be tuned with different DOC. Considering that free volume flow is determined by its flow coefficient and concentration, we proposed to control the deformation characteristics of metallic glass in micro-grooving by heat treatment and verified its effectiveness experimentally. • Materials removal mode of metallic glass changes with the increase of depth of cut. • The evolution of deformation mechanisms was studied using a dynamic model. • Free volume flow affects the evolution of deformation mechanisms significantly. • Deformation characteristics of metallic glass were experimentally modulated.

Maximizing the Flap Inflow in a Foot Reconstruction: Ultrasonographic Evaluation of Artery Flow in Accordance with the Angle of the Ankle.

Adequate arterial inflow is mandatory for a successful free tissue transfer. Maximizing this inflow appears to be especially important during distal lower extremity reconstruction, where perfusion pressures can be significantly lower than in the trunk or head and neck. In the current study, the authors used color and pulsed-wave Doppler ultrasonography to analyze blood flow volumes in the foot in accordance with the ankle position. Twenty feet of 10 healthy subjects were included in the analyses. All subjects were examined by Doppler ultrasonography at three different ankle angles (dorsiflexion at 90 degrees, relaxed position, and complete plantar flexion). The average flow volumes of the dorsalis pedis artery varied dramatically at the different ankle positions, as follows: dorsiflexion, 19.81 ± 3.88 ml/minute; relaxed position, 11.71 ± 4.72 ml/minute; and plantar flexion, 3.47 ± 1.41 ml/minute. The average flow volume of the posterior tibial artery also varied dramatically at these different ankle positions: dorsiflexion, 9.08 ± 8.25 ml/minute; relaxed position, 14.78 ± 2.45 ml/minute; and plantar flexion, 19.03 ± 5.03 ml/minute. The ankle position dramatically affects the flow velocity in the anterior and posterior tibial vessels, which is an important consideration when performing free tissue transfer reconstruction of the foot. Ankle dorsiflexion would be recommended when using the anterior tibial artery as a recipient vessel, whereas plantar flexion of the ankle would be advised when the posterior tibial artery is used as a recipient vessel.

Study of Four Passive Second Skin Façade Configurations as a Natural Ventilation System During Winter and Summer

The fight against climate change is a significant challenge, resulting mainly from the linear and extensive exploitation of natural resources, particularly fossil fuels. Its impacts are now recognized. The current climate models are neither sustainable nor ecological in economic and social terms, especially as we live in a century marked by galloping demography and urbanization. Researchers worldwide have paid great attention to passive solar design strategies such as double skin or Second Skin Façade. From this point, the present work aims to contribute to a better understanding of the feasibility of using a passive façade as a useful technology for natural ventilation to achieve potential energy savings and improve thermal comfort and indoor air quality. For this purpose, a parametric study was conducted for a room with four different southern facade configurations in six Moroccan climatic zones; the difference between each lies in the vent's position in the entrance and exit. This process was done by using COMSOL Multiphysics software. Velocity and volume flow rate fields were analyzed. The proposed configurations provided an average volume flow rate between 200 m3/h and 400 m3/h for a surface of 1 m2 of southern façade with an air vent area of 0.1mx0.2m.

Non-uniform pumping flow model for the couple stress particle-fluid under magnetic effects

In this article, peristaltically induced motion of couple stress fluid under the suspension of small particles have been studied. A peristaltic wave with non-uniform motion is traveling with a constant wave celerity. An extrinsic magnetic field is applied to an electrically conducting incompressible fluid with irrotational motion. Lubrication theory is applied for the mathematical formulation of both fluid- and particle-phase equations. Analytically and numerically, the formulated equations are solved using computational software Mathematica. The exact solutions are determined against the velocity profile for both fluid- and particulate-phases. The volumetric flow rate is also presented and calculated numerically to examine the pumping characteristics. Trapping mechanisms via streamlines are plotted and discussed against all the leading parameters. The present results are also beneficial to observe the Newtonian behavior and single phase fluid model. It is also observed that magnetic field opposes the fluid movement in the middle of the channel, while the presence of small particles tends to resist the fluid motion along the whole channel. A significant reduction in the pumping rate was observed due to the rise in the couple stress fluid parameter, the fraction of the particle volume, and the average volume flow rate, but a dual behavior is observed against the magnetic parameter. The fluid bolus diminishes in magnitude and reduces in quantity against the higher values of Hartmann number.