scholarly journals Numerical Simulation of Effects of River Reconstruction on Flooding: A Case Study of the Ba River, China

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Haixiao Jing ◽  
Yongbiao Lang ◽  
Xinhong Wang ◽  
Mingyang Yang ◽  
Zongxiao Zhang
Keyword(s):  
Flow Velocity ◽  
Eddy Currents ◽  
Human Life ◽  
River Channel ◽  
Computational Domain ◽  
River Channels ◽  
One Dimensional ◽  
Local Reconstruction ◽  
Before And After ◽  
Flood Flow

The local reconstruction of river channels may pose obstacles of flood flow, local eddy currents, or high flow velocity which pose potential threats to human life and infrastructures nearby. In the design of such projects, the effects of local reconstruction of the river channel on flooding are often evaluated by the one-dimensional method, which is based on the formula of one-dimensional nonuniform flow. In this study, a two-dimensional hydrodynamic model based on shallow water equations is employed to investigate the impacts of river reconstruction on flooding in the Ba River, China. The finite volume method and an unstructured triangular mesh are used to solve the governing equations numerically. The numerical model is validated by comparison with the results of a physical model of 1 : 120 scale. The backwater effects and impacts of flood flow fields under two flood frequencies are analyzed by comparing the numerical results before and after local reconstruction. The results show that the backwater length under both 10-year and 100-year floods can be reached up to the upstream boundary of the computational domain. However, the maximum water level rises are limited, and the levees in this river channel are safe enough. The flow velocity fields under both floods are changed obviously after local reconstruction in the Ba River. Areas with the potential for scour and deposition of the river bed are also pointed out. The findings of this study are helpful for the evaluation of flood risks of the river.

scholarly journals Flow velocity behavior programming on open channel bends

2021 ◽  
Vol 878 (1) ◽  
pp. 012049
Author(s):  
S Setiyadi
Keyword(s):  
Flow Velocity ◽  
Transverse Direction ◽  
Open Channel ◽  
Transverse Velocity ◽  
River Channel ◽  
River Channels ◽  
Flood Prevention ◽  
Channel Bend ◽  
Secondary Velocity

Abstract Flow velocity on open channel bends generally experiences additional velocity which is called secondary velocity. This paper aims to analyse and calculate the velocity that occurs in an open channel bend in general. The calculation that the writer uses is the calculation with fortran programming, in a case study of a river that bends, where the variables that must be present are given. The results of calculations and measurements of Secondary Speeds that occur at channel bends in this Open Channel will be very useful for river channel improvement or flood prevention in river channels, especially on existing bends. The conclusion is that at the bend of an open channel or river, there will be an increase in flow velocity in the transverse direction. This additional velocity is caused by the additional secondary velocity, namely the transverse velocity.

Intraoperative transesophageal assessment of coronary artery flow can predict 5 type myocardial infarction

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
A Zagatina ◽  
M Novikov ◽  
N Zhuravskaya ◽  
V Balakhonov ◽  
S Efremov ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Cardiac Surgery ◽  
Coronary Artery ◽  
Flow Velocity ◽  
Coronary Flow ◽  
Index Number ◽  
Left Main ◽  
Coronary Flow Velocity ◽  
Before And After ◽  
Flow Velocities

Abstract Background Stenosis of a coronary artery results in an increase in flow velocity in the pathologic segment. Effective grafting should decrease the stenotic native coronary velocity according to hemodynamic law. The range of decreased velocity before and after cardiac surgery can hypothetically reflect the effectiveness of a graft. The aim of the study is to determine if measuring coronary flow velocity changes during coronary artery bypass grafting (CABG) can predict intraoperative myocardial infarction. Methods One hundred sixty-six (166) consecutive patients (121 men, 64±9 years old) referred for cardiac surgery, were prospectively included in the study. A standard basic perioperative transesophageal echocardiography (TEE) examination was performed with additional scans of the left main, left anterior descending (LAD), and circumflex (LCx) arteries' proximal segments. Measurements of coronary flow velocities were performed before and after grafting in the same sites of the arteries. The maximal value of cardiac troponin I (cTnI) after CABG and the additive criteria were accounted for in the analysis as it is described in the expert consensus document for Type 5 myocardial infarction (MI) definition. Results One hundred sixty-three patients (98%) had arterial hypertension, 28 patients (17%) had diabetes mellitus, 35 patients (21%) were currently smokers. The feasibility of coronary flow assessment during cardiac operations was 95%. Before grafting, the mean velocity in the left main artery was 91±49 cm/s, in LAD 101±35 cm/s, and in LCx 117±49 cm/s. There was a significant correlation between changes in coronary flow velocities during operation and the value of cTnI (R=0.34, p<0.0001). Ten patients met the criteria for Type 5 MI. There were no differences in age, body mass index, number of coronary arteries with stenoses, frequency of prior MI, ejection fraction or coronary flow velocity before surgery in patients with and without Type 5 MI. The group of patients with Type 5 MI had an increase in native artery velocities during surgery in comparison with patients without MI, who had a significant decrease in coronary flow velocity after grafting (30±48 vs. −10±30 cm/s; p<0.0006). Increases in native coronary velocities greater than 3 cm/s predicted Type 5 MI with 81% accuracy (sensitivity 88%, specificity 70%). Conclusion Coronary flow velocity assessment during cardiac surgery could predict an elevation of cardiac troponins and Type 5 MI. Funding Acknowledgement Type of funding source: None

Abortion and its consequences before and after legalization

1927 ◽  
Vol 23 (2) ◽  
pp. 258-258
Author(s):  
G. Baksht
Keyword(s):  
Ethical Issues ◽  
Human Life ◽  
Point Of View ◽  
Before And After ◽  
Comprehensive Coverage

From a social point of view, the problem of abortion was and is, perhaps, more topical today than ever before. The comprehensive coverage of this problem, which involves the most intimate aspect of human life, social and domestic conditions, and ethical issues, can only be the product of the collective efforts of physicians, sociologists, and lawyers.

scholarly journals Doppler Flow Velocity Indices (RI, PI, S/D & PSV) of Fetal Middle Cerebral Artery in Normal Pregnancies: Correlation with Gestational Age of 20 to 40 Weeks

2012 ◽  
Vol 2 (2) ◽  
pp. 77-80
Author(s):  
Md Abu Taher ◽  
Nuzhat Tasmin ◽  
AS Mohiuddin ◽  
Md Mohit Ul Alam ◽  
Md Mofazzal Sharif ◽  
...  
Keyword(s):  
Middle Cerebral Artery ◽  
Flow Velocity ◽  
Cerebral Artery ◽  
Gestational Age ◽  
Resistance Index ◽  
Peak Systolic Velocity ◽  
Doppler Flow ◽  
Significant Difference ◽  
Before And After ◽  
Doppler Indices

This observational type of descriptive study was carried out in the Department of Radiology and Imaging, BIRDEM selecting 70 Bangladeshi pregnant babies with the aim to find out the normogram of foetal middle cerebral artery Doppler flow velocity indices and correlation between Doppler flow velocity indices [Resistance Index (RI), Pulsatility Index (PI), Systolic/Diastolic ratio (S/D) & Peak Systolic Velocity (PSV)] of foetal middle cerebral artery and gestational age in normal pregnancies of 20 to 40 weeks. It was observed that RI, PI and S/D were decreased with the advance of gestational age but PSV was increases with the advance of gestational age. Statistical analyses showed there were significant difference between mean PSV, RI and PI before and after 25 weeks of gestation. No significant difference was found between mean S/D before and after 25 weeks of gestation. It was observed from Correlation analysis between Doppler indices with independent gestational age that all the Doppler indices of foetal middle cerebra artery was positively correlated with the whole gestation period. The statistical analysis showed only PSV and RI were significantly correlated with the gestational age. Simple regression analysis between dependent Doppler index with independent gestational age before and after 25 weeks revealed that all the Doppler indices had positive relationship with the corresponding gestational age but relationship between PSV and PI (before 25 weeks) with their corresponding gestational ages were only statistically significant.DOI: http://dx.doi.org/10.3329/birdem.v2i2.12306 Birdem Med J 2012; 2(2) 77-80

scholarly journals Help Rendered by Thozhi for Love Marriage

2020 ◽  
Vol 3 (1) ◽  
pp. 71-81
Author(s):  
Elavarasu R
Keyword(s):  
Human Life ◽  
Close Friend ◽  
Before And After ◽  
Love Marriage

We know that In Sangam Literature Thozhi (A Close Friend of Heroine) played a vital roll in hero and heroine’s life before and after their marriage. The parents have all rights to make arrangement of marriage for their daughter for their own wish. But, once a woman fall in love with a man and she would like to marry that man, in this situation the help rendered by Thozhi is inevitable. This article focuses to research the roll of Thozhi in hero and heroine’s love marriage which have been recorded in Sangam literature. The above said performance of Thozhi reflected her minute knowledge about human life, her fond of love on the heroine and smart action etc., Sangam literature recorded many knowledgeable and important activities of Thozhi. This article is like to reveal the various performances of Thozhi in the love marriage proposal of hero and heroine.

scholarly journals Estimation of peak discharges of historical floods

2014 ◽  
Vol 11 (5) ◽  
pp. 5463-5485 ◽  
Author(s):  
J. Herget ◽  
T. Roggenkamp ◽  
M. Krell
Keyword(s):  
Flood Frequency ◽  
River Channels ◽  
Sources Of Information ◽  
Mean Flow ◽  
General Outline ◽  
One Dimensional ◽  
Flood Level ◽  
Alternative Approaches ◽  
The Mean ◽  
Generalized Statement

Abstract. There is no doubt, that the hazard assessment of future floods especially under consideration of the recent environmental change can be significantly improved by the consideration of historic flood events. While flood frequency inventories on local, regional and even European scale are already developed and published, the estimation of their magnitudes indicated by discharges is still challenging. Such data are required due to significant human impact on river channels and floodplains though historic flood levels cannot be related to recent ones or recent discharges. Based on own experiences from single local key studies the general outline of an approach to estimate the discharge of the previous flood based on handed down flood level and topographic data is presented. The model for one-dimensional steady flow is based on the empirical Manning equation for the mean flow velocity. Background and potential sources of information, acceptable simplifications and data transformation for each element of the model-equation are explained and discussed. Preliminary experiences on the accuracy of ±10% are documented and potential approaches for the validation of individual estimations given. A brief discussion on benefits and limitations including a generalized statement on alternative approaches closes the review presentation of the approach.

scholarly journals Flood flow at the confluence of compound river channels

2015 ◽  
Author(s):  
T. Ishikawa ◽  
R. Akoh ◽  
N. Arai
Keyword(s):  
River Channels ◽  
Flood Flow

A simple calculation method for estimating the flow velocity on the roof of a train running through a tunnel using an unsteady incompressible flow model

2019 ◽  
Vol 234 (7) ◽  
pp. 734-748
Author(s):  
Katsuhiro Kikuchi ◽  
Satoru Ozawa ◽  
Yuhei Noguchi ◽  
Shinya Mashimo ◽  
Takanobu Igawa
Keyword(s):  
Boundary Layer ◽  
Flow Velocity ◽  
Calculation Method ◽  
Model Experiment ◽  
Flow Model ◽  
Simple Calculation ◽  
Dimensional Model ◽  
One Dimensional ◽  
Calculation Results ◽  
Tunnel System

Predicting the aerodynamic phenomena in a train-tunnel system is important for increasing the speed of railway trains. Among these phenomena, many studies have focused on the effects of pressure; however, only a few studies have examined the effects of flow velocity. When designing train roof equipment such as a pantograph and an aerodynamic braking unit, it is necessary to estimate the flow velocity while considering the influence of the boundary layer developed on the train roof. Until now, numerical simulations using a one-dimensional model have been utilized to predict the flow velocity around a train traveling through a tunnel; however, the influence of the boundary layer cannot be taken into consideration in these simulations. For this purpose, the authors have previously proposed a simple calculation method based on a steady incompressible tunnel flow model that can take into account the influence of the boundary layer, but this method could not incorporate the unsteadiness of the flow velocity. Therefore, in this study, the authors extend the previous simple calculation method such that it can be used for an unsteady incompressible tunnel flow. The authors compare the calculation results obtained from the extended method with the results of a model experiment and a field test to confirm its effectiveness.

scholarly journals An Improved Method Constructing 3D River Channel for Flood Modeling

Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 403 ◽  
Author(s):  
Pengbo Hu ◽  
Jingming Hou ◽  
Zaixing Zhi ◽  
Bingyao Li ◽  
Kaihua Guo
Keyword(s):  
High Resolution ◽  
River Channel ◽  
Hydrodynamic Process ◽  
River Channels ◽  
Section Data ◽  
Terrain Model ◽  
Digital Elevation ◽  
Hydrodynamic Processes ◽  
Hermite Spline ◽  
Elevation Model

The high-resolution topography is very crucial to investigate the hydrological and hydrodynamic process. To resolve the deficiency problem of high resolution terrain data in rivers, the Quartic Hermite Spline with Parameter (QHSP) method constructing the river channel terrain based on the limited cross-section data is presented. The proposed method is able to not only improve the reliability of the constructed river terrain, but also avoid the numerical oscillations caused by the existing constructing approach, e.g., the Cubic Hermite Spline (CHS) method. The performance of the proposed QHSP method is validated against two benchmark tests. Comparing the constructed river terrains, the QHSP method can improve the accuracy by at least 15%. For the simulated flood process, the QHSP method could reproduce more acceptable modeling results as well, e.g., in Wangmaogou catchment, the numerical model applying the Digital Elevation Model (DEM) produced by the QHSP method could increase the reliability by 18.5% higher than that of CHS method. It is indicated that the QHSP method is more reliable for river terrain model construction than the CHS and is a more reasonable tool investigating the hydrodynamic processes in river channels lacking of high resolution topography data.

scholarly journals P1564 Changes in coronary flow velocity measuring during coronary bypass grafting can predict elevation of cardiac troponin

2020 ◽  
Vol 21 (Supplement_1) ◽  
Author(s):  
A Zagatina ◽  
M Novikov ◽  
N Zhuravskaya ◽  
V Balakhonov ◽  
D Shmatov
Keyword(s):  
Coronary Artery ◽  
Flow Velocity ◽  
Cardiac Troponin ◽  
Coronary Flow ◽  
Bypass Grafting ◽  
Left Main ◽  
Coronary Flow Velocity ◽  
Before And After ◽  
Velocity Changes ◽  
75Th Quartile

Abstract Background Stenosis of a coronary artery results in an increase in flow velocity in the pathologic segment. Effective grafting should decrease the stenotic native coronary velocity according to a hemodynamic law. The range of decreased velocity can hypothetically reflect the effectiveness of a graft. Grafting effect insufficiencies often cause elevations in periprocedural cardiac troponin (cTn) elevation. The aim of the study is to determine, if measuring coronary flow velocity changes during coronary artery bypass grafting (CABG) can predict further cTn elevation. Methods and results Consecutive 68 patients (48 men, 64 ± 9 years old), who were referred for CABG, were included into the study. A standard basic perioperative transesophageal echocardiography (TEE) examination was performed with additional scans of the left main, left anterior descending (LAD), and circumflex (LCx) arteries’ proximal segments. Measurements of coronary flow velocities was performed before and after grafting in the same sites of the arteries. The maximal value of cTnI within 48 hours after CABG was accounted for in the analysis. All patients had arterial hypertension, 15 patients (22%) had diabetes mellitus, 12 patients (18%) was current smokers. Forty-one patients (60%) had prior myocardial infarctions, 18 persons (26%) had previous coronary stenting. The ejection fraction before the operation was 56 ± 13%. Before grafting the mean velocity in the left main artery was 79 cm/s (25th-75th quartile, 42-111), in LAD 98 cm/s (25th-75th quartile, 71-125), and in LCx 116 cm/s (25th-75th quartile, 68-156). There was a strong significant correlation between changes in coronary flow velocities and the value of cTnI (R = 0.56, p < 0.0004). The patients with and without significant elevations in cTnI had differences in coronary velocity changes before and after grafting (p < 0.009). Patients with elevated cTnI in more than 5 times, had, on average, an increase in the velocities for native arteries of 21 ± 19 cm/s. Conclusion Coronary flow velocity assessment during CABG could predict an elevation of cardiac troponins after cardiac surgery. Abstract P1564 Figure.

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