Prediction of the lateral flow regime and critical depth in compound open channels

2009 ◽  
Vol 36 (1) ◽  
pp. 1-13 ◽  
Author(s):  
E. Kordi ◽  
S. A. Ayyoubzadeh ◽  
M. Z. Ahmadi ◽  
A. Zahiri
Keyword(s):  
Cross Sections ◽  
Specific Energy ◽  
Laboratory Data ◽  
Flow Distribution ◽  
Flow Regimes ◽  
Transitional Zone ◽  
Main Channel ◽  
Critical Depth ◽  
Single Cross Section ◽  
The Common

In this study, the common critical depth calculation in compound channels has been modified considering the effect of momentum transfer between the interface of a main channel and its floodplains. In noncorrected specific energy curves of a given slope, the flow is not necessarily entirely sub- or supercritical as it is in a single cross section and there is a possibility of both flow regimes at a certain stage, called the lateral mixed flow regimes, which makes the application of specific energy equation to determine the critical depth and transitional zone calculations questionable. In the present research, the flow distribution in a main channel and floodplains has been corrected by combining the corrected hydraulic flow in compound cross sections using the coherence method. The specific energy has been subsequently modified in the subsections. The results seem satisfactory when compared with the results based on the available laboratory data.

Anatomy of the adventitious roots of Philodendron (Araceae) and its importance for the systematics of the genus

2020 ◽  
Vol 33 (2) ◽  
pp. 207
Author(s):  
Rafaela de Oliveira Ferreira ◽  
Ana Cristina Campos Borges ◽  
Juan Augusto Rodrigues dos Campos ◽  
Artur Manoel Leite Medeiros ◽  
Cassia Mônica Sakuragui ◽  
...  
Keyword(s):  
Cross Sections ◽  
Related Species ◽  
Adventitious Roots ◽  
Related Genus ◽  
Phylogenetic Hypothesis ◽  
The Common

The genus Philodendron Schott comprises the following three currently accepted subgenenera: P. subg. Philodendron, P. subg. Pteromischum and P. subg. Meconostigma; however, these lack a well-defined classification. In the present study, we examined anatomically samples of adventitious roots in species of the group, so as to establish aspects relevant for taxonomic purposes. The anatomical analyses emphasised the characteristics of the steles in cross-sections of the root samples from regions near the apex to the most mature zones. A species of a closely related genus Adelonema, namely A. crinipes, was included in the study to clarify the results. Our results indicated notable differences in the species of the subgenus Meconostigma, mainly in terms of the presence (and variations) of a lobed stele, whereas the cylindrical stele stood out among the common characteristics in P. subg. Philodendron, P. subg. Pteromischum and the related species A. crinipes. Moreover, the characteristics shared by P. subg. Philodendron and P. subg. Pteromischum corroborated the phylogenetic hypothesis that these two taxa were more closely related to one another than to P. subg. Meconostigma.

3D modelling of the flow distribution in the delta of Lake Øyeren, Norway

2010 ◽  
Vol 41 (2) ◽  
pp. 92-103 ◽  
Author(s):  
Peggy Zinke ◽  
Nils Reidar Bøe Olsen ◽  
Jim Bogen ◽  
Nils Rüther
Keyword(s):  
Water Level ◽  
Cross Sections ◽  
Stokes Equations ◽  
Morphological Changes ◽  
Flow Distribution ◽  
Field Measurements ◽  
Navier Stokes ◽  
Error Sources ◽  
Navier Stokes Equations ◽  
Water Level Measurements

A 3D numerical model was used to compute the discharge distribution in the channel branches of Lake Øyeren's delta in Norway. The model solved the Navier–Stokes equations with the k–ɛ turbulence model on a 3D unstructured grid. The bathymetry dataset for the modelling had to be combined from different data sources. The results for three different flow situations in 1996 and 1997 showed a relative accuracy of the computed discharges within the range of 0 to±20% compared with field measurements taken by an ADCP at 13 cross sections of the distributary channels. The factors introducing the most error in the computed results are believed to be uncertainties concerning the bathymetry. A comparison between the computational results of the older morphology data from 1985–1990 and the model morphology from 1995–2004 indicated that morphological changes in this period had already had consequences for the flow distribution in some channels. Other important error sources were the inevitable use of averaged water level gradients because of unavailable water level measurements within the delta.

Monitoring and Assessment of Water Quality in Fuchunjiang and Hangzhou Reaches of Qiantangjiang Estuarine Zone

2013 ◽  
Vol 316-317 ◽  
pp. 711-714
Author(s):  
Zhi Yong Dong ◽  
Yong Gu ◽  
Shuo Shuo Wang ◽  
Ying Biao Shi ◽  
Ruo Hua Li ◽  
...  
Keyword(s):  
Water Quality ◽  
Cross Section ◽  
Cross Sections ◽  
Ph Value ◽  
Flood Plain ◽  
Quality Parameters ◽  
Main Channel ◽  
Water Quality Parameters ◽  
Vertical Line ◽  
Estuarine Zone

This paper presents monitoring investigation of water quality parameters in Fuchunjiang and Hangzhou reaches of Qiantang estuarine zone by YSI 6600 V2-4-M multi-parameter water quality sonde. The 7 monitoring cross-sections were streamwise placed, and the 2 vertical lines respectively located in flood plain and main channel at each cross-section. Surface, intermediate and bed layers were chosen at each vertical line in main channel, and surface and bed layers at each vertical line in flood plain. At each vertical line, the main water quality parameters such as dissolved oxygen, salinity, turbidity, pH value, electrical conductivity and oxidation reduction potential were monitored, variation of these parameters along longitudinal and vertical directions analyzed, and water quality conditions at each monitoring cross-section assessed.

scholarly journals Calculation of Multiple Critical Depths in Open Channels Using an Adaptive Cubic Polynomials Algorithm

Water ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 799 ◽  
Author(s):  
Ioannis Petikas ◽  
Evangelos Keramaris ◽  
Vasilis Kanakoudis
Keyword(s):  
Computer Program ◽  
Specific Energy ◽  
Simple Formula ◽  
The Other ◽  
Critical Depth ◽  
Compound Channel ◽  
Local Minima ◽  
Analysis System ◽  
Cubic Polynomials ◽  
The Given

A method for the calculation of multiple critical depths in compound and natural channels, using an adaptive cubic polynomials algorithm (ACPA), is presented in this paper. The algorithm is based on the approximation of the specific energy with multiple cubic polynomials. The roots of these polynomials’ derivatives are determined to calculate all local minima and maxima. These extremities yield the critical depths. Furthermore, the Froude number can be calculated at any elevation by applying a simple formula after calculating the derivative of the corresponding polynomial, which contains the given elevation. The algorithm developed was tested on various compound and natural channels. Its results were then compared with the results provided by the HEC-RAS (Hydrologic Engineering Center – River Analysis System) computer program, proving that in some cases ACPA results were more accurate than those of HEC-RAS. This has to do with the fact that HEC-RAS algorithm determines a single critical depth and is better fitted to simple prismatic channels. On the other hand, the ACPA algorithm is able to calculate all critical depths of a natural or compound channel, providing thus more accurate results.

A Parallel Implementation of 3D Computed Tomography Algorithm

2015 ◽  
Vol 770 ◽  
pp. 491-494
Author(s):  
Andrey E. Kovtanyuk
Keyword(s):  
Computed Tomography ◽  
3D Reconstruction ◽  
Density Distribution ◽  
Cross Section ◽  
Cross Sections ◽  
Input Data ◽  
Parallel Implementation ◽  
Back Projection ◽  
Single Cross Section ◽  
Single Cross

A computed tomography problem as a 3D reconstruction of density distribution is considered. The input data are obtained as a result of irradiations. The solution of the computed tomography problem is presented as a set of cross-section images. The reconstruction in a single cross-section is performed by algorithm of convolution and back projection. The parallelization is fulfilled over a set of cross-sections by use of the MPI technology.

New method for determining correction factors for pin-in-paste solder volumes

2017 ◽  
Vol 29 (1) ◽  
pp. 2-9 ◽  
Author(s):  
Oliver Krammer ◽  
Bertalan Varga ◽  
Karel Dušek
Keyword(s):  
Explicit Expression ◽  
Cross Sections ◽  
New Method ◽  
Solder Paste ◽  
Correction Factors ◽  
Surface Evolver ◽  
Volume Calculation ◽  
Content Type ◽  
The Common ◽  
Approach Zero

Purpose This paper aims to present a new method to calculate the appropriate volume of solder paste necessary for the pin-in-paste (PIP) technology. By the aid of this volume calculation, correction factors have been determined, which can be used to correct the solder fillet volume obtained by an explicit expression. Design/methodology/approach The method is based on calculating the optimal solder fillet shape and profile for through-hole (TH) components with given geometrical sizes. To calculate this optimal shape of the fillet, a script was written in Surface Evolver. The volume calculations were performed for different fillet radiuses (0.4-1.2 mm) and for different component lead geometries (circular and square cross-sections). Finally, the volume obtained by the Evolver calculations was divided by the volume obtained by an explicit expression, and correction factors were determined for the varying parameters. Findings The results showed that the explicit expression underestimates the fillet volume necessary for the PIP technology significantly (15-35 per cent). The correction factors for components with circular leads ranged between 1.4 and 1.59, whereas the correction factors for square leads ranged between 1.1 and 1.27. Applying this correction can aid in depositing the appropriate solder paste volume for TH components. Originality/value Determining the correct volume of solder paste necessary for the PIP technology is crucial to eliminate the common soldering failure of TH components (e.g. voiding or non-wetted solder pads). The explicit expression, which is widely used for volume calculation in this field, underestimates the necessary volume significantly. The new method can correct this estimation, and can aid the industry to approach zero-defect manufacturing in the PIP technology.

scholarly journals Development of the computerized decision-making support system for the prevention and revealing of dangerous zones of flooding

2019 ◽  
Vol 97 ◽  
pp. 05040 ◽  
Author(s):  
Farrukh Shaazizov ◽  
Bakhtiyar Uralov ◽  
Elyor Shukurov ◽  
Aydar Nasrulin
Keyword(s):  
Cross Sections ◽  
Calculation Method ◽  
Visual Inspection ◽  
Wave Speed ◽  
Emergency Situation ◽  
Technical Condition ◽  
The Common ◽  
The Given ◽  
Modern Condition ◽  
Partial Destruction

In considered article the results are presented of the carried out researches on high-mountainous lakes of the Tashkent area. Visual inspection of a modern condition of natural dams of considered high-mountainous lakes of the Tashkent oblast is carried out. On the basis of the analysis of visual inspection it is possible to note, that the common technical condition of natural dams of the submitted high-mountainous lakes safe and does not represent danger to downstream situated territories. It was carried out the modeling of occurrence of emergency situation on high-mountainous lakes of the Tashkent oblast in case of full or partial destruction of natural dams. By an available calculation method of flooding waves are determined its key parameters, height of a wave, speed of distribution of a wave of break on the certain distances and reaching time the given wave up to the certain distances. On the basis of calculation method have been calculated and put on cross-sections of the rivers Pskem and Kocy zones of possible flooding in full and partial destruction of dams of high-mountainous lakes. Results of the carried out calculations have been put on the digital map, created on platform ArcView 3.2a.

Efficiency of visual strength grading of timber with respect to origin, species, cross section, and grading rules: a critical evaluation of the common standards

Holzforschung ◽  
2014 ◽  
Vol 68 (2) ◽  
pp. 203-216 ◽  
Author(s):  
Peter Stapel ◽  
Jan-Willem G. van de Kuilen
Keyword(s):  
Mechanical Properties ◽  
Cross Section ◽  
Cross Sections ◽  
Critical Evaluation ◽  
International Standards ◽  
National Standards ◽  
Visual Grading ◽  
Source Areas ◽  
The Common ◽  
Machine Strength

Abstract Strength grading is essential for the efficient use of structural timber. Although international standards exist for machine strength grading, visual grading is still regulated based on national rules, which are expected to allow safe and economic grading results. Although there are large differences in the graded output because the species, the cross section, and the origin of the timber influence the results, some of these standards are considered to be applicable universally. The present article demonstrates how the chosen standards influence the grading results. Depending on the parameters, the yields or the mechanical properties are low compared with the declared values. The results also show the efficiency and applicability of different national standards for strength grading of timber from various origins. Furthermore, it is recommended to reconsider the existing limits for source areas and cross sections given in the standard EN 1912.

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