Changes In Flow Speed Research Articles

Position-dependent roles of somatic cells in phototaxis of Volvox

Abstract A spherical green alga, Volvox, achieves phototaxis via a simple on/off switch of flagellar beating in response to changes in light intensity, without the need for complex signal transduction between cells. Moreover, the alga can change its susceptibility to light in order to adapt to its environment. To identify the mechanisms of susceptibility regulation, experiments were conducted at three different levels: population, individual, and cellular. The light intensity dependence of the average velocity at the population level and that of the change in flow speed obtained at the individual level were consistent, indicating that susceptibility regulation occurred in each Volvox colony. Furthermore, by measuring the probability of stopping flagellar beating when the light intensity was changed, susceptibility regulation was found to result from the properties of somatic cells as differential and adaptive photosensors. These photosensing properties deteriorated from the anterior to the posterior regions of the colony. Considering the mechanical motion of a Volvox colony, the position-dependent ability of somatic cells indicates that the anterior cells play the role of a rudder, whereas the posterior cells play the role of a rower. The position-dependent properties of somatic cells imply an early stage of cell differentiation that allows for an efficient response to changes in the circumstances.

Performance Development of Fluidic Oscillator Nozzle for Cleaning Autonomous-Driving Sensors

Contaminated autonomous-driving sensors frequently malfunction, resulting in accidents; these sensors need regular cleaning. The autonomous-driving sensor-cleaning nozzle currently used is the windshield-washer nozzle; few studies have focused on the sensor-cleaning nozzle. We investigated the flow characteristics of the nozzle to improve its performance in cleaning the autonomous-driving sensor. The nozzle concept was based on the fluidic oscillator nozzle. Various performance parameters of the fluidic oscillator nozzle were selected and investigated. Transient fluid flow was simulated to determine the effect of the design parameters to maximize the oscillation flow phenomenon. Additionally, the spray angle and frequency were calculated. Analysis results showed that the change in flow speed affects the frequency, and the change in feedback-channel-inlet flow rate affects the angle change. To verify the simulation result, the three best models (R4+RC10, R6+RC11, R8+RC10) and the base model were manufactured and tested. The test results were consistent with the simulation results within a 6% error.

Time-Lagged Functional Ultrasound for Multi-Parametric Cerebral Hemodynamic Imaging.

We introduce an ultrasound speckle decorrelation-based time-lagged functional ultrasound technique (tl-fUS) for the quantification of the relative changes in cerebral blood flow speed (rCBF [Formula: see text]), cerebral blood volume (rCBV) and cerebral blood flow (rCBF) during functional stimulations. Numerical simulations, phantom validations, and in vivo mouse brain experiments were performed to test the capability of tl-fUS to parse out and quantify the ratio change of these hemodynamic parameters. The blood volume change was found to be more prominent in arterioles compared to venules and the peak blood flow changes were around 2.5 times the peak blood volume change during brain activation, agreeing with previous observations in the literature. The tl-fUS shows the ability of distinguishing the relative changes of rCBFspeed, rCBV, and rCBF, which can inform specific physiological interpretations of the fUS measurements.

Myosin-independent stiffness sensing by fibroblasts is regulated by the viscoelasticity of flowing actin

The stiffness of the extracellular matrix induces differential tension within integrin-based adhesions, triggering differential mechanoresponses. However, it has been unclear if the stiffness-dependent differential tension is induced solely by myosin activity. Here, we report that in the absence of myosin contractility, 3T3 fibroblasts still transmit stiffness-dependent differential levels of traction. This myosin-independent differential traction is regulated by polymerizing actin assisted by actin nucleators Arp2/3 and formin where formin has a stronger contribution than Arp2/3 to both traction and actin flow. Intriguingly, despite only slight changes in F-actin flow speed observed in cells with the combined inhibition of Arp2/3 and myosin compared to cells with sole myosin inhibition, they show a 4-times reduction in traction than cells with myosin-only inhibition. Our analyses indicate that traditional models based on rigid F-actin are inadequate for capturing such dramatic force reduction with similar actin flow. Instead, incorporating the F-actin network’s viscoelastic properties is crucial. Our new model including the F-actin viscoelasticity reveals that Arp2/3 and formin enhance stiffness sensitivity by mechanically reinforcing the F-actin network, thereby facilitating more effective transmission of flow-induced forces. This model is validated by cell stiffness measurement with atomic force microscopy and experimental observation of model-predicted stiffness-dependent actin flow fluctuation.

Exploring traffic breakdown with vehicle-level data

Traffic breakdown involves complicated vehicle behavior, and is regarded as a probabilistic event with macroscopic traffic data from fixed detectors. However, with the advent of connected vehicle technologies, traffic data will develop to the vehicle-level, such as trajectory data, and provide unprecedented opportunities to better understand various traffic phenomena. Using novel vehicle-level data from drone videos, this research explores the traffic breakdown by interactions between vehicles. Specifically, this paper categorizes the typical behavior of individual vehicles that causes or resolves traffic congestion. Based on the behavior that occurred in the extensive time–space domain, this research develops a novel measurement method to quantify the behavior as temporal delay or spatial residual. With real-world data, this research verifies the vehicle-level congestion can be estimated from specific vehicle behavior, and their aggregation could describe the change in flow speed or traffic breakdown. The proposed framework can address the traffic phenomenon better when more extensive data is available.

Development of High-Precision Urban Flood-Monitoring Technology for Sustainable Smart Cities.

Owing to rapid climate change, large-scale floods have occurred yearly in cities worldwide, causing serious damage. We propose a real-time urban flood-monitoring technology as an urban disaster prevention technology for sustainable and secure smart cities. Our method takes advantage of the characteristic that water flow is regularly detected at a certain distance with a constant Doppler velocity within the radar observation area. Therefore, a pure flow energy detection algorithm in this technology can accurately and immediately detect water flow due to flooding by effectively removing dynamic obstacles such as cars, people, and animals that cause changes in observation distance, and static obstacles that do not cause Doppler velocities. Specifically, in this method, the pure flow energy is detected by generating a two-dimensional range-Doppler relation map using 1 s periodic radar observation data and performing statistical analysis on the energy detected on the successive maps. Experiments to verify the proposed technology are conducted indoors and in real river basins. As a result of conducting experiments in a narrow indoor space that could be considered an urban underpass or underground facility, it was found that this method can detect flooding situations with centimeter-level accuracy by measuring water level and flow velocity in real time from the time of flood occurrence. And the experimental results in various river environments showed that our technology could accurately detect changes in distance and flow speed from the river surface. We also confirmed that this method could effectively eliminate moving obstacles within the observation range and detect only pure flow energy. Finally, we expect that our method will be able to build a high-density urban flood-monitoring network and a high-precision digital flood twin.

Lumped parameter liver simulation to predict acute haemodynamic alterations following partial resections.

Partial liver resections are routinely performed in living donor liver transplantation and to debulk tumours in liver malignancies, but surgical decisions on vessel reconstruction for adequate inflow and outflow are challenging. Pre-operative evaluation is often limited to radiological imaging, which fails to account for post-resection haemodynamic alterations. Substantial evidence suggests post-surgical increase in local volume flow rate enhances shear stress, signalling hepatic regeneration, but excessive shear stress has been postulated to result in small for size syndrome and liver failure. Predicting haemodynamic alterations throughout the liver is particularly challenging due to the dendritic architecture of the vasculature, spanning several orders of magnitude in diameter. Therefore, we developed a mathematical lumped parameter model with realistic heterogeneities capturing inflow/outflow of the human liver to simulate acute perfusion alterations following surgical resection. Our model is parametrized using clinical measurements, relies on a single free parameter and accurately captures established perfusion characteristics. We quantify acute changes in volume flow rate, flow speed and wall shear stress following variable, realistic liver resections and make comparisons with the intact liver. Our numerical model runs in minutes and can be adapted to patient-specific anatomy, providing a novel computational tool aimed at assisting pre- and intra-operative surgical decisions for liver resections.

Design and Demonstration of a Passive Pitch System for Tidal Turbines

Tidal currents are renewable and predictable energy sources that could prove fundamental to the transition to a sustainable use of renewable energy resources. Over a tidal period, changes in the flow speed in a tidal channel require that the blade pitch is adjusted to maximise power extraction. This is currently achieved with active pitch actuation, which however increases the capital and maintenance cost of the turbine. Furthermore, because of turbulence in the tidal stream, turbine yaw, wave-induced currents, etc., tidal turbine blades experience high-frequency velocity fluctuations that result in power and thrust unsteadiness, both of which are transmitted to the generator, the tower, and the active pitching mechanism, shortening the operating life due to fatigue loading.
 A passive morphing blade concept capable of reducing the load fluctuations without affecting the mean loads has recently been formulated and demonstrated with low-order simulations (https://doi.org/10.1016/j.renene.2021.10.085) and measurements (https://doi.org/10.1016/j.renene.2023.01.051). The system allows both passive pitch adjustment to changes in the mean flow speed over the tidal period, and the mitigation of high-frequency fluctuations.
 In this paper, we present the recent progress on the development of morphing blade technology, including with numerical simulations and experimental tests on a 1.2-m diameter turbine. Two different design concepts have been tested in the FloWave facility at the University of Edinburgh and in the recirculating channel at the Institute for Marine Engineering of the Italian National Research Council, respectively.
 Experimental results show that the amplitude of power variations over a wide range of flow speeds is substantially decreased, while thrust variations with changes in freestream speed are essentially suppressed. The detrimental effect of yawed inflow is, in addition, almost entirely cancelled. The fluctuations in the root-bending moment, thrust and torque are consistently reduced over a broad range of tip-speed ratios. We also show that such a system, if improperly designed, could result in a negative starting torque, and we show the steps necessary to avoid this issue.
 Furthermore, we present a theoretical and numerical framework that allows the design of passive pitch blades that can cancel either thrust or power fluctuations in specific flow conditions, as well as mitigating both types of fluctuations over a wide range of conditions. Specifically, we show that for any quasi-steady change in the relative flow speed and direction, there is a pitching axis that allows a chosen force component to be kept constant. High-frequency force fluctuations can also be substantially mitigated, and the extent of the mitigation depends on the inertia and friction in the system.
 Overall this paper demonstrates experimentally the effectiveness of morphing blades for tidal turbines and presents a theoretical and numerical framework for the future development of this technology.

Impact of Medieval Climate Anomaly and Little Ice Age on the Labrador Current flow speed and the AMOC reconstructed by the sediment dynamics and biomarker proxies

It is widely accepted that the changes in freshwater transport into the Labrador Sea occurred during the Medieval Climate Anomaly (MCA) and Little Ice Age (LIA), which were instrumental in modifying the climate surrounding the North Atlantic. However, the extent to which paleo proxies accurately reflect freshwater transport is poorly known due simply to lack of data. This study provides the first direct proxy record of freshwater supply by the sediment dynamics sortable silt proxy for the past 1.45 ka. A sediment core MO2009061–0217 (46.387°N, 46.742°W) retrieved off the SE Grand Banks along the flow path of the Labrador Current was used to determine the sortable silt and extract lipid biomarkers. The sortable silt data were converted to current speed (cm/s), which suggests that the Labrador Current was weak during the MCA and most vigorous during the LIA. One concurrent water column temperature proxy, namely TEX86 based on glycerol dialkyl glycerol tetraethers (GDGTs), shows that the outer Labrador Current water was cooler during the LIA than the MCA. In contrast, the converse temperature changes were recorded along the inner Labrador Current, where temperature change was slight. Our data are placed with a few high-resolution (i.e., multi-decadal) published temperature data to reflect broader changes in the subpolar northwestern Atlantic. The temperature variations on the SE Grand Banks are analogous to those between northern Iceland and Greenland shelves over this period and reflect changes in the subpolar gyre geometry of the North Atlantic. We hypothesize that the heterogenous temperatures coupled to changes in the Labrador Current flow speed were modulated by subpolar ocean currents on the SE Grand Banks.

Speed-resolved perfusion imaging using multi-exposure laser speckle contrast imaging and machine learning.

Laser speckle contrast imaging (LSCI) gives a relative measure of microcirculatory perfusion. However, due to the limited information in single-exposure LSCI, models are inaccurate for skin tissue due to complex effects from e.g. static and dynamic scatterers, multiple Doppler shifts, and the speed-distribution of blood. It has been demonstrated how to account for these effects in laser Doppler flowmetry (LDF) using inverse Monte Carlo (MC) algorithms. This allows for a speed-resolved perfusion measure in absolute units %RBC × mm/s, improving the physiological interpretation of the data. Until now, this has been limited to a single-point LDF technique but recent advances in multi-exposure LSCI (MELSCI) enable the analysis in an imaging modality. To present a method for speed-resolved perfusion imaging in absolute units %RBC × mm/s, computed from multi-exposure speckle contrast images. An artificial neural network (ANN) was trained on a large simulated dataset of multi-exposure contrast values and corresponding speed-resolved perfusion. The dataset was generated using MC simulations of photon transport in randomized skin models covering a wide range of physiologically relevant geometrical and optical tissue properties. The ANN was evaluated on in vivo data sets captured during an occlusion provocation. Speed-resolved perfusion was estimated in the three speed intervals 0 to , 1 to , and , with relative errors 9.8%, 12%, and 19%, respectively. The perfusion had a linear response to changes in both blood tissue fraction and blood flow speed and was less affected by tissue properties compared with single-exposure LSCI. The image quality was subjectively higher compared with LSCI, revealing previously unseen macro- and microvascular structures. The ANN, trained on modeled data, calculates speed-resolved perfusion in absolute units from multi-exposure speckle contrast. This method facilitates the physiological interpretation of measurements using MELSCI and may increase the clinical impact of the technique.

Interpreting inverse correlation time: From blood flow to vascular network

The inverse correlation time (ICT) is a key quantity in laser speckle contrast imaging (LSCI) measurements. Traditionally, ICT is regarded as a metric of blood flow, such as speed or perfusion. However, we highlight that ICT not only contains important information about blood flow, but also reflects the underlying structure of the vascular network. In the past, ICT has been found to be correlated with vessel diameter. Here, we further report that ICT exhibits a different sensitivity to blood flow depending on vessel orientation. Specifically, ICT is more sensitive to blood flow speed changes in vessels descending from or arising to the tissue surface, compared with those laying parallel to the surface. Those findings shift our understanding of ICT from purely blood flow to a combination of blood flow and vascular network structure. We also develop theories to facilitate the study of vascular network’s impact on ICT.

Glaciological history and structural evolution of the Shackleton Ice Shelf system, East Antarctica, over the past 60 years

Abstract. The discovery of Antarctica's deepest subglacial trough beneath the Denman Glacier, combined with high rates of basal melt at the grounding line, has caused significant concern over its vulnerability to retreat. Recent attention has therefore been focusing on understanding the controls driving Denman Glacier's dynamic evolution. Here we consider the Shackleton system, comprised of the Shackleton Ice Shelf, Denman Glacier, and the adjacent Scott, Northcliff, Roscoe and Apfel glaciers, about which almost nothing is known. We widen the context of previously observed dynamic changes in the Denman Glacier to the wider region of the Shackleton system, with a multi-decadal time frame and an improved biannual temporal frequency of observations in the last 7 years (2015–2022). We integrate new satellite observations of ice structure and airborne radar data with changes in ice front position and ice flow velocities to investigate changes in the system. Over the 60-year period of observation we find significant rift propagation on the Shackleton Ice Shelf and Scott Glacier and notable structural changes in the floating shear margins between the ice shelf and the outlet glaciers, as well as features indicative of ice with elevated salt concentration and brine infiltration in regions of the system. Over the period 2017–2022 we observe a significant increase in ice flow speed (up to 50 %) on the floating part of Scott Glacier, coincident with small-scale calving and rift propagation close to the ice front. We do not observe any seasonal variation or significant change in ice flow speed across the rest of the Shackleton system. Given the potential vulnerability of the system to accelerating retreat into the overdeepened, potentially sediment-filled bedrock trough, an improved understanding of the glaciological, oceanographic and geological conditions in the Shackleton system are required to improve the certainty of numerical model predictions, and we identify a number of priorities for future research. With access to these remote coastal regions a major challenge, coordinated internationally collaborative efforts are required to quantify how much the Shackleton region is likely to contribute to sea level rise in the coming centuries.

Measuring capillary flow dynamics using interlaced two-photon volumetric scanning

Two photon microscopy and optical coherence tomography (OCT) are two standard methods for measuring flow speeds of red blood cells in microvessels, particularly in animal models. However, traditional two photon microscopy lacks the depth of field to adequately capture the full volumetric complexity of the cerebral microvasculature and OCT lacks the specificity offered by fluorescent labeling. In addition, the traditional raster scanning technique utilized in both modalities requires a balance of image frame rate and field of view, which severely limits the study of RBC velocities in the microvascular network. Here, we overcome this by using a custom two photon system with an axicon based Bessel beam to obtain volumetric images of the microvascular network with fluorescent specificity. We combine this with a novel scan pattern that generates pairs of frames with short time delay sufficient for tracking red blood cell flow in capillaries. We track RBC flow speeds in 10 or more capillaries simultaneously at 1 Hz in a 237 µm × 237 µm × 120 µm volume and quantified both their spatial and temporal variability in speed. We also demonstrate the ability to track flow speed changes around stalls in capillary flow and measure to 300 µm in depth.

Comparative Study of Flow Patterns around Rhizophora and Avicennia Mangrove Roots Using Computational Fluid Dynamics Simulation

The goal of this research is to visualize and compare the patterns of the fluid flow around stilt roots of Rhizophora mangrove species and pneumatophore roots of Avicennia mangrove species in Pichavaram mangrove forest to better understand how mangrove roots can potentially slow down heavy wind flow and thereby offer protection to the coast from natural disasters. The flow around the roots is simulated and analyzed using ANSYS Computational Fluid Dynamics (CFD) software using an unsteady k-ε turbulence model. Wind and water flow velocities vary with respect to time during tsunami, cyclones, typhoons, or hurricanes. Hence, inlet velocity taken as the step function is applied to simulate the change in speed of fluid flow to study the flow behavior. Velocity and pressure are measured at various points around Rhizophora and Avicennia mangrove roots. The findings of the simulation reveal that the Rhizophora stilt roots and pneumatophore roots of Avicennia marina continuously lower the fluid velocity. The Rhizophora mangrove roots can largely decrease the flow velocity because of the complexity and its root dimensions in comparison to Avicennia roots. The data obtained from this research can be applied to increase the efficiency of breakwater models and, as a result, safeguard the shore from natural disasters.

An 80 kyr record of intermediate‐depth water flow on the western South Atlantic margin

AbstractUnderstanding the Antarctic Intermediate Water transport is fundamental to knowing the Atlantic Meridional Overturning Circulation and its variations over time. This study investigates the temporal variations of the northward flow of the Intermediate Western Boundary Current (the leading carrier of the Antarctic Intermediate Water) over the last 80 kyr by using grain‐size data (sortable silt and end‐member analysis). The results presented show abrupt changes in Sortable Silt (interpreted as changes in flow speed) in the transition between Marine Isotope Stage 4 and Marine Isotope Stage 3 and during Marine Isotope Stage 3. In addition, there is a clear coarsening of Sortable Silt from the Deglacial to the Holocene, indicating an intensification of the northward transport of the Antarctic Intermediate Water along the south‐western Atlantic margin. These results highlight the existence of a prevailing positive relationship between the northward carrier of the Antarctic Intermediate Water and the Atlantic Meridional Overturning Circulation over the last 80 kyr, with a negative relationship at the beginning of Marine Isotope Stage 3 and over the Holocene. This contribution states that the positive relationship between the Antarctic Intermediate Water and the Atlantic Meridional Overturning Circulation is a dynamic interconnection that needs to be further constrained by future works.

In vivo assessment of hypertensive nephrosclerosis using ultrasound localization microscopy.

As a typical chronic kidney disease (CKD), hypertensive nephrosclerosis (HN) is a common syndrome of hypertension, characterized by chronic kidney microvascular damage. Early diagnosis of microvascular damage using conventional ultrasound imaging encounters challenges in sensitivity and specificity owing to the inherent diffraction limit. Ultrasound localization microscopy (ULM) has been developed to obtain microvasculature and microvascular hemodynamics within the kidney, and would be a promising tool for the early diagnosis of CKD. In this study, the advantage of quantitative indexes obtained by using ULM (mean arterial blood flow speeds of different segments of interlobular arteries) over indexes obtained using conventional clinical serum (β2-microglobulin, serum urea nitrogen, and creatinine) and urine (24-h urine volume and urine protein) tests and ultrasound Doppler imaging (peak systolic velocity [PSV], end-diastolic velocity [EDV], and resistance index [RI]) and contrast-enhanced ultrasound imaging (CEUS; rise time [RT], peak intensity [IMAX], mean transit time [mTT], and area under the time-intensity curve [AUC]) for early diagnosis of HN were investigated. Examinations were carried out on six spontaneously hypertensive rats (SHR) and five normal Wistar-Kyoto (WKY) rats at the age of 10weeks. The experimental results show that the indicators derived from conventional clinical inspections (serum and urine tests) and ultrasound imaging (PSV, EDV, RI, RT, IMAX, mTT, and AUC) do not show significant difference between hypertensive and healthy rats (p>0.05), while the TTP of the SHR group (28.52 ± 5.52 s) derived from CEUS is significantly higher than that of the WKY group (18.68 ± 7.32 s; p<0.05). The mean blood flow speed in interlobular artery of SHR (12.47 ± 1.06mm/s) derived from ULM is significantly higher than that of WKY rats (10.13 ± 1.17mm/s; p<0.01). The advantages of ULM over conventional clinical inspections and ultrasound imaging methods for early diagnosis of HN were validated. The quantitative results show that ULM can effectively diagnose HN at the early stage by detecting the blood flow speed changes of interlobular arteries. ULM may promise a reliable technique for early diagnosis of HN in the future.

Changes in area, flow speed and structure of southwest Antarctic Peninsula ice shelves in the 21st century

Abstract Since the mid-20th century, ice shelves around the Antarctic Peninsula have declined in extent and thickness, and some have shown signs of structural instability. Here, using satellite imagery from 1999/2000 to 2019/20 (Landsat 7 and 8, Sentinel-2 and ASTER), we measure areal changes, calculate surface flow speeds, and quantify structural changes of Bach, Stange and George VI ice shelves, located in the southwest Antarctic Peninsula. We recorded a total area loss of 797.5 km2 from 2009/10 to 2019/20, though spatial and temporal patterns varied at individual ice fronts. Flow speeds remained largely stable over the observation periods, but notable acceleration was calculated for Bach Ice Shelf, and at the northern and southern extents of George VI Ice Shelf. Open fractures widened and lengthened between 2009/10 and 2019/20 on all three ice shelves. We conclude that Stange Ice Shelf is stable, and not under any immediate threat of enhanced recession. Continued ice-mass loss and consequential speed up of George VI South may cause further fracturing and destabilisation in the coming decades. Of more immediate concern are the glaciological changes noted for Bach Ice Shelf and George VI North; substantial areas of stabilising ice have already, or will soon be removed, that may lead to enhanced recession within the next decade.

Contrasting Westward and Eastward Propagating Mesoscale Eddies in the Global Ocean

Although the zonal propagation of mesoscale eddies is intrinsically westward in oceans worldwide, eddies occasionally propagate eastward. Westward propagating eddies (WPEs) and eastward propagating eddies (EPEs) have distinctively different characteristics. In this article, the propagation features of WPEs and EPEs were studied using a combination of current, wind, and topographical data. We found that, except for in the North Atlantic, the energetic areas for WPEs and EPEs did not overlap. Furthermore, the propagation channels of WPEs and EPEs were located at different depths. The magnitude of change in current and wind stress simultaneously affected both the spread direction and velocity of eddies. The average translation speeds of eddies increased as subsurface current velocity increased, regardless of the angle between the direction of eddy propagation and flow. Compared with WPEs, increases in wind stress had little effect on the propagation speeds of EPEs. The directions of EPEs were more sensitive to changes in flow and wind speed. Even small changes in bathymetry slowed the propagation speeds of eddies. This topographical inhibition was biggest when the topographic gradients were around 0.02 and 0.04 for WPEs and EPEs, respectively. The propagation directions of EPEs were also sensitive to the surrounding terrain and tended to move along seamounts and ridges. These findings may refine eddy predictions and aid eddy observations in the future.

전기자동차 배터리 모듈의 공기 냉각 최적화 설계

The Due to the development of the industry, the demand for electricity is increasing, and the use of fossil fuels is causing global warming and various environmental pollution problems. Recently, electric vehicles (EV) driven by Li-ion battery are one of the solution to overcome environmental and energy crisis. Due to high energy density, Li-ion batteries have become a necessity for electric vehicles (EV). The weakness of lithium-ion batteries, which are important as solutions to environment-friendly energy, is the thermal problem. So, in the current study, the CFD simulation study was conducted to solve this thermal problem induced from Li-ion batteries. The thermal behavior of cylindrical battery cells due to the change of air flow speed was carried out using the CFD analysis program. It was confirmed that the temperature of the cell decreased as the velocity increased. However, an appropriate velocity was set because the cell could not withstand when applying a high velocity which the pressure drop issue can be existed. As a result, it was found that even at the same temperature, the temperature has different values depending on the cell position. At the same time, it was found that the closer the inlet area and outlet area, the lower the temperature of the cell.

Blood flow in the umbilical vein of the fetus in first half of pregnancy

The present investigation aims at studying the blood flow in the umbilical vein in the first half of normal pregnancy. It was shown that the establishing of hemocirculation passes through 4 periods: 8- 10th, 11-12th, 13-16th and after the 16th week of pregnancy. Besides that, statistically verified changes in maximum blood flow speed and index of pulsation in this vessel were revealed. Constant bloodstream spectrum reflects stability of oxygenic bloodsupply of the fetus.