Wall Flow Research Articles

Experimental Investigation of a Helium-Cooled Breeding Blanket First Wall under LOFA Conditions and Pre-Test and Post-Test Numerical Analysis

The experimental investigation of a prototypical set-up simulating a loss of flow accident in a helium-cooled breeding blanket first wall mock-up under typical heat load conditions is presented. The experimental campaign reproduces the expected DEMO thermal-hydraulics conditions during normal and off-normal situations and aims at providing some insight into the fast transients associated with the loss of flow in the blanket first wall. The experimental set-up and the definition of the experimental matrix are discussed, including pre-test analysis performed in support of these activities. The major experimental results are discussed, and a procedure of using the acquired data for validating and calibrating the RELAP-3D model of the mock-up is introduced. All these activities contributed to the creation of a relevant theoretical and practical experience that can be used in further studies concerning incidental transients in real-plant scenarios in the framework of DEMO plant fusion safety activities.

CFD simulation of flow distribution in the randomly packed bed Dixon ring

ABSTRACT The maldistribution in randomly packed beds with a high diameter ratio is a result of wall-flow formation and channeling. In this study, the thin randomly packed bed (dp/D = 1/8) filled with Dixon ring is simulated with a porous media model. The motivation of our study is to understand the effect of surface tension and liquid inlet velocity on the height of the wall-flow formation. Furthermore, the flow structure in this packed bed was described by numerical simulation. The results show that increasing the liquid inlet velocity and surface tension causes a faster distribution of liquid flow that led to faster formation of wall flow. Increasing the surface tension from 0.05 to 0.07 N/m causes the lower wall-flow formation from 0.19 m to 0.15 m in liquid velocity of 0.015 m/s and 0.09 to 0.06 in liquid velocity of 0.08 m/s. According to the findings, the 30% increasing the surface tension (from 0.07 N/m to 0.085 N/m) led to 30% decreases in height of wall-flow formation in the case of lower liquid velocity (0.015 m/s) and 50% decreases in the height of wall-flow formation in case of higher liquid velocity (0.08 m/s).

In Vitro Red Blood Cell Segregation in Sickle Cell Anemia

Red blood cells in sickle cell anemia (sRBC) are more heterogeneous in their physical properties than healthy red blood cells, spanning adhesiveness, rigidity, density, size, and shape. sRBC with increased adhesiveness to the vascular wall would trigger vaso-occlusive like complications, a hallmark of sickle cell anemia. We investigated whether segregation occurs among sRBC flowing in micron-sized channels and tested the impact of aggregation on segregation. Two populations of sRBC of different densities were separated, labeled, and mixed again. The mixed suspension was flowed within glass capillary tubes at different pressure-drops, hematocrit, and suspending media that promoted or not cell aggregation. Observations were made at a fixed channel position. The mean flow velocity was obtained by using the cells as tracking particles, and the cell depleted layer (CDL) by measuring the distance from the cell core border to the channel wall. The labeled sRBC were identified by stopping the flow and scanning the cells within the channel section. The tube hematocrit was estimated from the number of fluorescence cells identified in the field of view. In non-aggregating media, our results showed a heterogeneous distribution of sRBC according to their density: low-density sRBC population remained closer to the center of the channel, while the densest cells segregated towards the walls. There was no impact of the mean flow velocity and little impact of hematocrit. This segregation heterogeneity could influence the ability of sRBC to adhere to the vascular wall and slow down blood flow. However, promoting aggregation inhibited segregation while CDL thickness was enhanced by aggregation, highlighting a potential protective role against vaso-occlusion in patients with sickle cell anemia.

Effect of Emissary Vein on Hemodynamics of the Transverse- Sigmoid Sinus Junction.

Objective: To investigate the effect of the blood flow direction and afflux location of emissary veins (EVs) on the hemodynamics of the transverse-sigmoid sinus (TS-SS) junction.Methods: A patient-specific geometric model was constructed using computed tomography venography (CTV) and 4D flow MR data from a venous pulsatile tinnitus (PT) patient. New EV models were assembled with the afflux at the superior, middle and inferior portions of the SS from the original model, and inlet and outlet directions were applied. Computational fluid dynamics (CFD) simulation was performed to analyze the wall pressure and flow pattern of the TS-SS junction in each condition.Results: Compared to the model without EVs, the wall pressure was greatly increased in models with inlet flow and greatly decreased in models with outlet flow. The more closely the EV approached the TS-SS, the larger the pressure in models with inlet flow, and the smaller the pressure in models with outlet flow. The flow streamline in the lateral part of the TS-SS junction was smooth in all models. The streamlines in the medial part were regular spirals in outlet models and chaotic in inlet models. The streamlines showed no obvious changes regardless of afflux location. The velocity at the TS-SS junction of inlet models were uniform, medium-low flow rate, while in control and outlet models were the lateral high flow rate and the central low flow rate.Conclusion: The flow direction and afflux location of EVs affect the hemodynamics of the TS-SS junction, which may influence the severity of PT.

Computational simulation of rheological blood flow containing hybrid nanoparticles in an inclined catheterized artery with stenotic, aneurysmal and slip effects

Influenced by nano-drug delivery applications, the present article considers the collective effects of hybrid biocompatible metallic nanoparticles (Silver and Copper), a stenosis and an aneurysm on the unsteady blood flow characteristics in a catheterized tapered inclined artery. The non-Newtonian Carreau fluid model is deployed to represent the hemorheological characteristics in the arterial region. A modified Tiwari-Das volume fraction model is adopted for nanoscale effects. The permeability of the arterial wall and the inclination of the diseased artery are taken into account. The nanoparticles are also considered to have various shapes (bricks, cylinders, platelets, blades) and therefore the influence of different shape parameters is discussed. The conservation equations for mass, linear momentum and energy are normalized by employing suitable non-dimensional variables. The transformed equations with associated boundary conditions are solved numerically using the FTCS method. Key hemodynamic characteristics i.e. velocity, temperature, flow rate, wall shear stress (WSS) in stenotic and aneurysm region for a particular critical height of the stenosis, are computed. Hybrid nanoparticles (Ag–Cu/Blood) accelerate the axial flow and increase temperatures significantly compared with unitary nanoparticles (Ag/blood), at both the stenosis and aneurysm segments. Axial velocity, temperature and flow rate are all enhanced with greater nanoparticle shape factor. Axial velocity, temperature, wall shear stress and flow rate magnitudes are always comparatively higher at the aneurysm region compared with the stenotic segment. The simulations provide novel insights into the performance of different nanoparticle geometries and also rheological behaviour in realistic nano-pharmaco-dynamic transport and percutaneous coronary intervention (PCI).

Aeroelastic response of a propulsive rotor blade with synthetic jets

Understanding the aeroelastic response of a propulsive rotor blade is critical to implementing active flow control techniques to mitigate blade structural vibration. In this experimental study, the coupling between rotor blade aerodynamic loading and first flap mode bending and torsion is explored. The three-bladed rotor is 2.58 m in diameter, and contains a NACA 0012 airfoil with zero pre-built twist. Each blade contains 20 high-performance synthetic jet actuators distributed along the span and are activated with a constant mean jet velocity of 66.3 m/s. The rotor was tested at rotor speeds, Ω of 250, 500, 750, and 1000 revolutions per minute (RPM) and collective blade pitch angles, θc of 2, 5, and 8 degrees. Rotor thrust and torque were measured using a high-capacity load cell, and the flow near the blade tip was measured using laser Doppler velocimetry (LDV) techniques. Blade bending and torsion was measured at three equally spaced radial stations on the blade root, middle, tip regions defined by r/R= 0.32, 0.64, and 0.96 respectively using three onboard electronic accelerometers. Synthetic jets reduce the near-wall streamwise velocity deficit and turbulence intensity in the near wall flow, improving the sectional lift coefficient of the blade and delaying flow separation which results in marginally higher thrust and lower torque loading of up to 7.4% and 4.3 % respectively. At higher rotor speeds of 750 and 1000 RPM, there is a pronounced non-linear increase in bending and torsion along blade span. In the blade tip region, the streamwise flow undergoes a significant decrease in velocity and momentum, which contributes to instabilities in the boundary layer with early-stage unsteady flow separation at θc= 8°. This is correlated to a dramatic rise in the baseline power spectral density (PSD) at the blade’s natural frequency along with an increase in root mean square (rms) of bending acceleration and blade pitch angle, where the maximum values measured are arms= 0.74 g and θrms= 1.45°.

Solution of 2D nonstationary problem of hydrogeology for groundwater level detection in different phases of open pit mining

Solution of any problem of hydrogeology, especially pit wall slope stability design, needs information on groundwater levels in different phases of open pit mining. The groundwater level is mostly determined from the numerical modeling of fluid flows. The unsteady fluid flow modeling is a labor-consuming process and it often involves 3D methods of finite elements, finite volumes and finite differences, which requires much time and is sometimes impossible because of the lack of the source data. The fastest way of determining groundwater levels and fluid flow parameters in wanted directions at different times of open pit mining is the solution of 2D nonstationary problem of hydrogeology using the finite element method. The problem solving details are insufficiently described in technical literature, and the present authors instantiate the process by comparing the Rocscience Slide 2 application with the analytical solutions. The 2D unstable groundwater flow in the pit wall was modeled for 5 time periods: open pit mine life for 1460 days; every year until termination of open pit mining; time of the steady-state flow setting 25 years long. The modeling domain is found based on the open pit mine geometry, topography and impact radius. The impact radius is 1357 m. The model identifies a single aquifer with the permeability of 0.69 m/day. The model groundwater level deviates from the in-situ measurements taken in observation wells at a distance of 23 m by 2.5 %.

A Numerical Investigation Into the Heat Transfer Performance and Particle Dynamics of a Compressible, Highly Mass Loaded, High Reynolds Number, Particle Laden Flow

Abstract In this work, we study the heat transfer performance and particle dynamics of a high mass-loaded, compressible, particle-laden flow in a horizontally oriented pipe using an Eulerian–Eulerian (two-fluid) computational model. Previous experimental work by our group provides the basis for the study. Specifically, a 17 bar coflow of nitrogen gas and copper powder are modeled with inlet Reynolds numbers of 3 × 104, 4.5 × 104, and 6 × 104 and mass loadings of 0, 0.5, and 1.0. Eight binned particle sizes were modeled to represent the known powder properties. Significant settling of all particle groups is observed leading to asymmetric temperature distributions. Wall and core flow temperature distributions are observed to agree well with measurements. In high Reynolds number cases, the predictions of the multiphase computational model were satisfactorily aligned with the experimental results. Low Reynolds number model predictions were not as consistent with the experimental measurements.

Elucidation of material removal mechanism in float polishing

Float polishing (FP) is a non-contact polishing method in which a thin layer of fluid is maintained between the workpiece and precision lap by hydrodynamic pressure effect. While it is known to consistently produce atomically flat surfaces with little or no sub-surface damage, the characteristics of polishing fluid flow and material removal have not been studied in-depth. In this research, the underlying mechanism in FP is investigated by means of computational fluid dynamics (CFD) and molecular dynamics (MD) simulation. It is revealed that a fluid gap few microns in height is generated by the wedge effect of slurry. The near wall flow condition is further investigated by direct observation and tracing of cavitation bubbles. Abrasive particle trajectory tracing is carried out with a well calibrated CFD model, and suggests that single abrasive particles move almost parallel to the workpiece surface at a relative speed of around 0.5 mm/s. Next, single abrasive particle interactions with the surface of a Ni crystal are simulated by MD to predict the required conditions in terms of kinetic energy for effective smoothing of the surface. Finally, it is concluded that the material removal mechanism in FP is dependent on a minimum size of nano-abrasive agglomerates of several 100 nm, and the existence of two types of smoothing phenomena: atomic removal and atomic transfer.

Investigations into the Potential of Using Open Source CFD to Analyze the Differences in Hemodynamic Parameters for Aortic Dissections (Healthy versus Stanford Type A and B)

The objective of this study was to develop a method to evaluate the effects of an aortic dissection on hemodynamic parameters by conducting a comparison with that of a healthy (nondissected) aorta. Open-source software will be implemented, no proprietary software/application will be used to ensure accessorily and repeatability, in all the data analysis and processing. Computed tomography (CT) images of aortic dissection are used for the model geometry segmentation. Boundary conditions from literature are implemented to computational fluid dynamics (CFD) to analyze the hemodynamic parameters. A numerical simulation model was created by obtaining accurate 3-dimensional geometries of aortae from CT images. In this study, CT images of 8 cases of aortic dissection (Stanford type-A and type-B) and 3 cases of healthy aortae are used for the actual aorta model geometry segmentation. These models were exported into an open-source CFD software, OpenFOAM, where a simplified pulsating flow was simulated by controlling the flow pressure. Ten cycles of the pulsatile flow (0.50 sec/cycle) conditions, totaling 5 sec, were calculated. The pressure distribution, wall shear stress (WSS) and flow velocity streamlines within the aorta and the false lumen were calculated and visualized. It was found that the flow velocity and WSS had a high correlation in high WSS areas of the intermittent layer between the true and false lumen. Most of the Stanford type-A dissections in the study showed high WSS, over 38 Pa, at the systole phase. This indicates that the arterial walls in type-A dissections are more likely to be damaged with pulsatile flow. Using CFD to estimate localized high WSS areas may help in deciding to treat a type-A or B dissection with a stent graft to prevent a potential rupture.

High-resolution heat transfer measurements on a rotating turbine endwall with infrared thermography

Computational thermo-fluid dynamics in the field of turbo machinery research tend to account for transient interaction mechanisms to predict the convective heat transfer within the hot gas path. In this context, the rotor hub side endwall region of the high pressure turbine depicts an object of interest as the near wall flow field may be dominated by rotating flow structures emerging from the disc space cavities. The validation of the applied numerical tools rely on experimental heat transfer setups reproducing such transient boundary conditions. This paper describes an experimental approach to quantify the heat transfer coefficient and the adiabatic wall temperature on the rotating endwall of a large scale test turbine. The wall heat flux distribution in a thin film isolator coated to a well conducting support structure is quantified for a series of quasi-isothermal boundary conditions. A high-resolution infrared camera is used to capture triggered thermograms of the rotating surface. Distributed thermocouples in the base body serve as reference points for camera calibration and to deduce the temperature distribution at the interface to the isolator. The calibration is in-situ and includes the pixel-wise quantification of uncertainties in the surface temperatures. An advanced linear fit approach is applied to derive the unknown adiabatic quantities and their uncertainties. For the examined operating point with a rim seal purge flow rate of 1% the random part of the relative measurement uncertainty is clearly below 10% for the heat transfer coefficient and below 5% for the adiabatic wall temperature. As the evaluation algorithm is designed to consider covariances between the thermocouple and infrared readings, the surface wall heat flux can be evaluated for every single infrared image.

The susceptibility of the aortic root: porcine aortic rupture testing under cardiopulmonary bypass

BackgroundIn our earlier study on the functional limits of the aneurysmal aortic root we determined the pig root is susceptible to failure at high aortic pressures levels. We established a pig rupture model using cardiopulmonary bypass to determine the most susceptible region of the aortic root under the highest pressures achievable using continuous flow, and what changes occur in these regions on a macroscopic and histological level. This information may help guide clinical management of aortic root and ascending aorta pathology.MethodsFive pigs underwent 4D flow MRI imaging pre surgery to determine vasopressor induced wall sheer stress and flow parameters. All pigs were then placed on cardiopulmonary bypass (CPB) via median sternotomy, and maximal aortic root and ascending aorta flows were initiated until rupture or failure, to determine the most susceptible region of the aorta. The heart was explanted and analysed histologically to determine if histological changes mirror the macroscopic observations.ResultsThe magnetic resonance imaging (MRI) aortic flow and wall sheer stress (WSS) increased significantly in all regions of the aorta, and the median maximal pressures obtained during cardiopulmonary bypass was 497 mmHg and median maximal flows was 3.96 L/m. The area of failure in all experiments was the non-coronary cusp of the aortic valve. Collagen and elastin composition (%) was greatest in the proximal regions of the aorta. Collagen I and III showed greatest content in the inner aortic root and ascending aorta regions.ConclusionsThis unique porcine model shows that the aortic root is most susceptible to failure at high continuous aortic pressures, supported histologically by different changes in collagen content and subtypes in the aortic root. With further analysis, this information could guide management of the aortic root in disease.

A Hydromechanical Perspective to Study the Effect of Body Acceleration through Stenosed Artery

The spread of numerous deadly diseases such as Thrombosis, Diabetes, Atherosclerosis and other cardiac diseases, carry on to be major root of demise and growing public curiosity about the prevention and treatment of such fatal disorders. Body acceleration has very important role on the flow through stenosed artery. In this research work a problem for irregular development in the inner wall of the artery is known atherosclerosis that settled as a result of buildup due to cholesterol on the arterial wall has been discussed. In this work the effects of body acceleration, slip velocity in presence of catheter on the wall shear, velocity profile and flow rate reveal the graphical finding for pulsatile blood flow in narrow blood vessels. Here it is shown that flow rate, velocity and shear stress escalate as body acceleration increases.

Characterization and Chromatographic Fingerprint Analysis of Traditional Wallflower Oil

Background and objective: Wallflower oil is made from the flowers of Erysimum cheiri (L.) Crantz which is a herb rich in cardenolide compounds. Wallflower oil was traditionally indicated for analgesic, anti-inflammatory, hair tonic, and wound healing purposes. In this paper, wallflower oil was prepared based on the method cited in Persian medicine resources. Methods: To prepare the oil, 250 g dried flower was soaked in 5000 g distilled water for 20 h. Then, it was boiled for 2 h till half of the water volume evaporated. The obtained decoction was filtered and boiled in 2500 g sesame oil until all the aqueous part evaporated. The quality control tests were performed. Results: Acid, peroxide, iodine, and saponification values were determined as 0.72±0.02 (oleic acid%), 7.16±0.10 (meq/kg oil), 104.73±0.71 (g of I2/100 g oil), and 242.85±0.29 (mg KOH/g oil), respectively. HPTLC analysis revealed the presence of cardenolide compounds in wallflower oil, decoction, maceration, and flower samples. GC-FID results recognized linoleic acid (42.91%), oleic acid (41.22%), and palmitic acid (9.76%) as major fatty acids of wallflower oil. In addition, GC-MS study identified 11 volatile compounds among which, thymol (28.13%), carvacrol (21.63%), and dodecane (11.50%) were recognized as the main components. Conclusion: Thymol and carvacrol could be used for evaluation and determination of wallflower oil. On the other hand, presence of cardenolides in wallflower oil and consequent probable cardiac actions should be considered during clinical administrations. This paper recommends further in vitro and in vivo studies as well as clinical trials to evaluate the safety and efficacy of wallflower oil.

Stability analysis of open-channel flows with secondary currents

This paper presents some results coming from a linear stability analysis of turbulent depth-averaged open-channel flows (OCFs) with secondary currents. The aim was to identify plausible mechanisms underpinning the formation of large-scale turbulence structures, which are commonly referred to as large-scale motions (LSMs) and very-large-scale motions (VLSMs). Results indicate that the investigated flows are subjected to a sinuous instability whose longitudinal wavelength compares very well with that pertaining to LSMs. In contrast, no unstable modes at wavelengths comparable to those associated with VLSMs could be found. This suggests that VLSMs in OCFs are triggered by nonlinear mechanisms to which the present analysis is obviously blind. We demonstrate that the existence of the sinuous instability requires two necessary conditions: (i) the circulation of the secondary currents $\omega$ must be greater than a critical value $\omega _c$ ; (ii) the presence of a dynamically responding free surface (i.e. when the free surface is modelled as a frictionless flat surface, no instabilities are detected). The present paper draws some ideas from the work by Cossu, Hwang and co-workers on other wall flows (i.e. turbulent boundary layers, pipe, channel and Couette flows) and somewhat supports their idea that LSMs and VLSMs might be governed by an outer-layer cycle also in OCFs. However, the presence of steady secondary flows makes the procedure adopted herein much simpler than that used by these authors.

Ducted wind turbines in yawed flow: a numerical study

Abstract. Ducted wind turbines (DWTs) can be used for energy harvesting in urban areas where non-uniform flows are caused by the presence of buildings or other surface discontinuities. For this reason, the aerodynamic performance of DWTs in yawed-flow conditions must be characterized depending upon their geometric parameters and operating conditions. A numerical study to investigate the characteristics of flow around two DWT configurations using a simplified duct-actuator disc (AD) model is carried out. The analysis shows that the aerodynamic performance of a DWT in yawed flow is dependent on the mutual interactions between the duct and the AD, an interaction that changes with duct geometry. For the two configurations studied, the highly cambered variant of duct configuration returns a gain in performance by approximately 11 % up to a specific yaw angle (α= 17.5∘) when compared to the non-yawed case; thereafter any further increase in yaw angle results in a performance drop. In contrast, performance of less cambered variant duct configuration drops for α>0∘. The gain in the aerodynamic performance is attributed to the additional camber of the duct that acts as a flow-conditioning device and delays duct wall flow separation inside of the duct for a broad range of yaw angles.

Комплексна променева діагностика некротичного ентероколіту в новонароджених

Актуальність. Некротичний (некротизуючий) ентероколіт (НЕК) (Р77) — неспецифічне запальне захворювання, що викликається інфекційними агентами на тлі незрілості механізмів місцевого захисту та/або гіпоксично-ішемічного ушкодження слизової кишечника, схильне до генералізації з розвитком системної запальної реакції. Мета дослідження: визначити рентгенологічні та ультразвукові симптоми НЕК у новонароджених залежно від стадії захворювання. Матеріали та методи. Проаналізовані рентгенограми та дані ультразвукової діагностики (УЗД) органів черевної порожнини 32 новонароджених, із них 28 (87,5 %) — недоношених, 4 (12,5 %) — доношених. Результати. НЕК 1-ї ст. виявлений у 18,8 % випадків: гіперпневматоз кишечника — у 16,7 %, петлі у вигляді «скоб», потовщення стінок кишечника — у 83,3 %, мілкі горизонтальні рівні рідини з газом над ними — у 33,3 %. При УЗД відмічені потовщення стінок кишечника, зниження перистальтики в уражених сегментах. НЕК 2-ї ст. діагностований у 31,3 % випадків: ригідні петлі кишечника — в 30 %, статичні петлі кишечника — в 40 %. При УЗД відмічено потовщення стінок кишечника, зниження перистальтики в уражених сегментах, наявність прозорого випоту. При кольоровому допплерівському картуванні — посилений чи гіперемічний тип кровотоку кишкової стінки. НЕК 3-ї ст. діагностований у 28,1 % випадків: пневматоз стінки кишки — у 77,8 %; на тлі тіні печінки спостерігалося повітря в гілках портальної вени — у 33,3 %. При УЗД виявлені ознаки запалення з боку стінки кишечника (77,8 %), пневматоз стінки кишки (88,9 %) і поширення газу в портальній вені (44,4 %). НЕК 4-ї ст. діагностований у 21,9 % випадків, головною ознакою був пневмоперитонеум. Висновки. Основною метою променевого дослідження дітей із НЕК є виявлення всього комплексу проявів, що дозволяють якомога раніше діагностувати захворювання і визначити адекватне для даного пацієнта лікування. Ультразвукове дослідження органів черевної порожнини необхідно проводити всім пацієнтам, особливо з неспецифічними рентгенологічними або сумнівними для НЕК клінічними ознаками.

Value of the ultrasound research in the diagnostic of acute strangulated small bowel obstruction

Purpose. To identify and evaluate the effectiveness of sonographic signs of intestinal ischemia in patients with strangulated small bowel obstruction.Materials and methods. For the period 2017–2019, 115 patients with SIO were treated at the N.V. Sklifosovsky Federal Research Institute of Emergency Medicine. There were 64 women (55.6%) and 51 men (44.4%). The mean age was 62 ± 15 years. In all patients, the diagnosis was verified intraoperatively. All patients underwent ultrasound examination of the abdominal cavity in B-mode with the assessment of blood flow of the intestinal wall in the mode of CDI. Patients were divided on the basis of intraoperative data into 2 groups. The first group: 63 (54.8%) patients with signs of ischemia of the strangulated loop of the intestine. The second group consisted of 21 (18.1%) patients in whom intestinal necrosis was detected. The comparison group included 31 (26.7%) patients with adhesive small bowel obstruction without intestinal strangulation.Results. The most informative signs of ischemia of the strangulated intestine of the loop are infiltrative changes of its mesentery. In the second and third groups 9 (14.3%) and 12 (57.1%) participants, respectively, showed severity of intestinal ischemia, compared with 1 participant (3.2%) in the first group. The next informative criterion is the thickening of more than 0.4 cm and edema of the intestinal wall. In the second and third groups 30 (47.6%) and 14 (66.6%), in the comparison group 4 (12.9%), akinesis of the strangulated loop and paresis of the entire small intestine also directly correlated with intestinal ischemia. The absence of differentiation of intestinal wall layers occurs in (23.8%), the absence of blood flow in the intestinal wall in the CDI mode (19%), gas inclusions in the intestinal wall (4.3%).Conclusion. The assessment of sonographic symptoms allows to diagnose the presence of ischemic changes in the intestinal wall and perform surgery before the development of necrosis in the early period. In cases of late admission of the patient to the hospital, with the onset of intestinal necrosis and the associated erased clinical picture, ultrasound allows to establish indications for surgery before the development of peritonitis.

649 EFFECTS OF THE PREPARATION METHOD ON THE ICG FLUORESCENCE BLOOD FLOW IN THE GASTRIC CONDUIT AFTER ESOPHAGECTOMY

Abstract In this study, we investigated how the blood flow of gastric conduit changed due to the difference in the lesser curvature cut line using ICG fluorescence imaging in patients with esophageal cancer. Methods A total of 193 cases of esophageal cancer surgery with gastric conduit reconstruction were included. (Conventional method) The lesser curvature cut line of the stomach was started from a distance of 5 cm from the pylorus (141 cases). (Current method) Gastric lesser curvature dissection was started from the last branch of the left gastric artery (52 cases). Blood flow of the gastric conduit was measured by the ICG fluorescence imaging, and the correlation between the changes in the gastric conduit and both blood flow and anastomotic failure was examined. Results Median length of the lesser curvature cut line was 10 cm from the pylorus in the current method, which was significantly longer than that in the conventional method (P < 0.001). Congestion at the tip of the gastric conduit were more observed in the conventional method (P = 0.02). The ICG fluorescent blood flow speed in the gastric conduit wall was 2.54 cm/s by the conventional method and 2.82 cm/s by the current method (P = 0.03). There were 23 cases (16.3%) of anastomotic leakage in the conventional method and 4 cases (7.7%) in the current method (P = 0.09). Conclusion By preserving the right gastric artery and vein, improvement of venous return is expected, and it is suggested that blood flow in the gastric conduit wall can be well maintained.

Prediction of time-varying inner wall temperature of surge lines by a dynamic neural network

Thermal fatigue, mainly caused by thermal stratification, is one of the major factors for reliability degradation of surge lines in nuclear power plants and is well managed through on-line temperature monitoring. However, the vast amount of outer wall temperature data generated by on-line temperature monitoring requires an efficient way of calculating the inner wall temperature. In this paper, the time-varying inner wall temperature is predicted rapidly and precisely using a dynamic artificial neural network model based on outer wall temperature and flow velocity. By optimizing the length of time series, the time delay of heat transfer between the inner wall and outer wall temperature is fully considered in the dynamic model. Consequently, the best root mean squared error of the temperature prediction is as low as 3.78. More importantly, the importance analysis based on dynamic model is also performed to quantify the importance of outer wall temperature variables, which can be used to optimize the arrangement of outer wall temperature measurement points for further applications under different circumstances to reduce cost while maintain high prediction accuracy. The results in this study will be helpful for the optimization of measurement points arrangement and rapid on-line thermal fatigue evaluation of nuclear power plants.