A simple diagnostic model for the cross-channel distribution of the depth average velocity in curved open channels

2020 ◽  
pp. 1-30
Author(s):  
Peter Russell ◽  
Ross Vennell
Keyword(s):  
Average Velocity ◽  
Open Channels ◽  
Diagnostic Model ◽  
Channel Distribution ◽  
The Cross

III. Hydraulic problems on the cross-sections of pipes and channels

1888 ◽  
Vol 44 (266-272) ◽  
pp. 101-109
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Open Channels ◽  
The Cross

In that division of hydromechanics which is devoted to the investigation of the flow of liquids through pipes and open channels, the resistance due to the friction of the contained liquid against the sides of the pipes or channels has led to expressions for the velocity as a function of the dimensions and shape of the cross-section commonly designated as the hydraulic mean depth. This quantity is defined as the quotient of the area of the cross-section of the liquid by that part of its perimeter in contact with the pipe or channel. In a full pipe this perimeter is identical with that of the pipe’s cross-section, and in practice this is generally a circle.

Dynamical aspects of shallow sea fronts

1981 ◽  
Vol 302 (1472) ◽  
pp. 563-581 ◽  
Keyword(s):  
Diffusion Equation ◽  
Vertical Mixing ◽  
Circulation Pattern ◽  
Viscosity Coefficient ◽  
Similarity Solutions ◽  
Tidal Mixing ◽  
Interfacial Friction ◽  
Diagnostic Model ◽  
Mean Flow ◽  
The Cross

We examine the role of internal friction in the evolution of a two-dimensional front in a rotating stratified fluid. For a two-layer fluid with interfacial friction the depth of the frontal interface satisfies a diffusion equation with respect to time and the cross-frontal coordinate. Similarity solutions are used to compare the behaviour of the front for linear and quadratic interfacial friction laws. For a continuously stratified front a simple formula is derived for the cross-frontal flow induced by friction, parametrized in terms of an eddy viscosity coefficient Av, provided that the Rossby and Ekman numbers are small. Outside surface and bottom Ekman layers the deptht) of an isopycnal with density p satisfies the diffusion equation z t — [(A 1 2/ / 2) where are the Väisälä and Coriolis frequencies, x is the cross-frontal coordinate and t is time. The consequences of this for the evolution and maintenance of a front are discussed. The circulation in tidal mixing fronts is examined, with results being presented for a semi-analytic diagnostic model, which is fitted to two particular continental shelf fronts. A prominent feature is a two-cell circulation pattern in the plane normal to the front. A variety of cross-frontal transfer mechanisms are discussed, with order-of-magnitude comparisons of their importance being made. Transfer by the mean flow appears to be more important than either shear flow dispersion or the flux associated with baroclinic eddies, but the results are sensitive to the parametrization of vertical mixing of momentum.

scholarly journals Study on the Characteristic Point Location of Depth Average Velocity in Smooth Open Channels: Applied to Channels with Flat or Concave Boundaries

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 430 ◽  
Author(s):  
Tongshu Li ◽  
Jian Chen ◽  
Yu Han ◽  
Zhuangzhuang Ma ◽  
Jingjing Wu
Keyword(s):  
Average Velocity ◽  
Characteristic Point ◽  
Vertical Direction ◽  
Side Wall ◽  
Mathematical Expression ◽  
Open Channels ◽  
Point Location ◽  
Flow Measurements ◽  
Characteristic Points ◽  
Concave Boundaries

Based on the flow partition theory, we derive a mathematical expression by using the log-law for the characteristic point location (CPL) of depth average velocity in channels with flat or concave boundaries. It can manifest the position of the characteristic points in the vertical direction relative to the channel side wall or bed. Taking rectangular and semi-circular channels as research objects, we put forward a method to calculate the discharge of channels with CPL. Additionally, we carried out some experiments on rectangular and semi-circular channel sections. CPL’s analytic expression is validated against experimental results through comparison of velocity and discharge. The proposed formulation of characteristic point location could be extensively employed in flow measurements of flat and concave boundary channels, which has practical application value in simplifying the flow measurement steps of open channels.

Effect of the Continuous Traverse Trajectory and Dynamic Error of the Vane Anemometer on the Accuracy of Average Velocity Measurements at the Cross-Section of the Mine Heading – Model-Based Testing

2014 ◽  
Vol 59 (4) ◽  
pp. 1051-1060 ◽  
Author(s):  
Paweł Jamróz
Keyword(s):  
Velocity Profile ◽  
Cross Section ◽  
Average Velocity ◽  
Dynamic Error ◽  
Measuring Instruments ◽  
Velocity Measurements ◽  
Model Based Testing ◽  
Measurement Signal ◽  
Stationary Signals ◽  
The Cross

Abstract This paper discusses the problem of measuring the average velocity at the cross-section of mine heading with the use of the continuous traverse method. Based on model testing, it has been shown that measurement signals, obtained along the traversing trajectory, belong to the group of non-stationary signals. The methodology of the traversing method measurements, with the aspect of capabilities of measuring instruments used for that purpose, has been analysed. Results of simulation tests concerning the dynamic response of a vane anemometer to the measurement signal for selected trajectories of the continuous traverse have been presented. For this purpose, a velocity profile presenting an expanded stream of undisturbed air flow in the excavation has been used. Attention has been paid to the problem of selecting an adequate trajectory of anemometer movement, as the value of the velocity measured at the cross-section depends on the trajectory

scholarly journals Ein einfaches Modell zum Vergleich der Theorien von Hauser-Feshbach und P. A. Moldauer

1968 ◽  
Vol 23 (7) ◽  
pp. 955-961
Author(s):  
F. Schmidt
Keyword(s):  
Elastic Scattering ◽  
Cross Section ◽  
Compound Nucleus ◽  
Cross Sections ◽  
Channel Model ◽  
Open Channels ◽  
Nucleus Formation ◽  
Compound Nucleus Formation ◽  
The Cross

We discuss and compare the theories of HAUSER and FESHBACH and P. A. MOLDAUER by a simple two channel model. It is found that after a good fit of parameters only the cross sections of compound-elastic scattering differ substantially. Most differences appear if there are a few open channels. The consequences for the cross section of compound nucleus formation and also for calculations by the evaporation mdel are considered. By our model an evident foundation is given for the statement that MOLDAUER'S theorie would be valid for 〈Γλc〉/D ≦ 1.

scholarly journals Oral Microbiome Characteristics in Patients With Autoimmune Hepatitis

2021 ◽  
Vol 11 ◽  
Author(s):  
Benchen Rao ◽  
Jiamin Lou ◽  
Haifeng Lu ◽  
Hongxia Liang ◽  
Juan Li ◽  
...  
Keyword(s):  
Autoimmune Hepatitis ◽  
Validation Cohort ◽  
Oral Microbiome ◽  
Diagnostic Tools ◽  
Diagnostic Model ◽  
Oral Microbiota ◽  
Microbiome Diversity ◽  
Gene Functions ◽  
Successful Establishment ◽  
The Cross

Autoimmune hepatitis (AIH) is a common cause of liver cirrhosis. To identify the characteristics of the oral microbiome in patients with AIH, we collected 204 saliva samples including 68 AIH patients and 136 healthy controls and performed microbial MiSeq sequencing after screening. All samples were randomly divided into discovery cohorts (46 AIH and 92 HCs) and validation cohorts (22 AIH and 44 HCs). Moreover, we collected samples of 12 AIH patients from Hangzhou for cross-regional validation. We described the oral microbiome characteristics of AIH patients and established a diagnostic model. In the AIH group, the oral microbiome diversity was significantly increased. The microbial communities remarkably differed between the two groups. Seven genera, mainly Fusobacterium, Actinomyces and Capnocytophaga, were dominant in the HC group, while 51 genera, Streptococcus, Veillonella and Leptotrichia, were enriched in the AIH group. Notably, we found 23 gene functions, including Membrane Transport, Carbohydrate Metabolism, and Glycerolipid metabolism that were dominant in AIH and 31 gene functions that prevailed in HCs. We further investigated the correlation between the oral microbiome and clinical parameters. The optimal 5 microbial markers were figured out through a random forest model, and the distinguishing potential achieved 99.88% between 46 AIH and 92 HCs in the discovery cohort and 100% in the validation cohort. Importantly, the distinguishing potential reached 95.55% in the cross-regional validation cohort. In conclusion, this study is the first to characterize the oral microbiome in AIH patients and to report the successful establishment of a diagnostic model and the cross-regional validation of microbial markers for AIH. Importantly, oral microbiota-targeted biomarkers may be able to serve as powerful and noninvasive diagnostic tools for AIH.

A New Approach to the Demonstration of Oxidase-Localization Using Tannic Acid Or Catechin

1973 ◽  
Vol 31 ◽  
pp. 698-699
Author(s):  
V. Mizuhira ◽  
Y. Futaesaku
Keyword(s):  
Cross Section ◽  
Tannic Acid ◽  
Elastic Fiber ◽  
The Other ◽  
New Approach ◽  
Tissue Block ◽  
Active Reaction ◽  
The Cross

Previously we reported that tannic acid is a very effective fixative for proteins including polypeptides. Especially, in the cross section of microtubules, thirteen submits in A-tubule and eleven in B-tubule could be observed very clearly. An elastic fiber could be demonstrated very clearly, as an electron opaque, homogeneous fiber. However, tannic acid did not penetrate into the deep portion of the tissue-block. So we tried Catechin. This shows almost the same chemical natures as that of proteins, as tannic acid. Moreover, we thought that catechin should have two active-reaction sites, one is phenol,and the other is catechole. Catechole site should react with osmium, to make Os- black. Phenol-site should react with peroxidase existing perhydroxide.

Structures Resembling Striated Rootlets in Oocytes

1972 ◽  
Vol 30 ◽  
pp. 124-125
Author(s):  
Valerie V. Ernst
Keyword(s):  
Golgi Complex ◽  
Fibrous Structure ◽  
Oocyte Development ◽  
The Cross

During the earliest stage of oocyte development in the limpet, Acmea scutum, Golgi complexes are small, few and randomly dispersed in the cytoplasm. As growth proceeds, the Golgi complexes increase in size and number and migrate to the periphery of the cell. At this time, fibrous structures resembling striated rootlets occur associated with the Golgi complexes. Only one fibrous structure appears to be associated with a Golgi complex.The fibers are periodically cross banded with an average of 4 dense fibrils and 6 lighter fibrils per period (Fig. 1). The cross fibrils have a center to center spacing of about 7 run which appears to be the same as that of the striated rootlets of the gill cilia in this animal.

Energy Distribution in Electron Beams

1972 ◽  
Vol 30 ◽  
pp. 568-569
Author(s):  
Tamotsu Ohno
Keyword(s):  
Electron Beam ◽  
Energy Distribution ◽  
Cross Section ◽  
Integral Curve ◽  
Electron Beams ◽  
Electron Gun ◽  
Angular Divergence ◽  
Apparent Increase ◽  
Integral Width ◽  
The Cross

The energy distribution in an electron; beam from an electron gun provided with a biased Wehnelt cylinder was measured by a retarding potential analyser. All the measurements were carried out with a beam of small angular divergence (<3xl0-4 rad) to eliminate the apparent increase of energy width as pointed out by Ichinokawa.The cross section of the beam from a gun with a tungsten hairpin cathode varies as shown in Fig.1a with the bias voltage Vg. The central part of the beam was analysed. An example of the integral curve as well as the energy spectrum is shown in Fig.2. The integral width of the spectrum ΔEi varies with Vg as shown in Fig.1b The width ΔEi is smaller than the Maxwellian width near the cut-off. As |Vg| is decreased, ΔEi increases beyond the Maxwellian width, reaches a maximum and then decreases. Note that the cross section of the beam enlarges with decreasing |Vg|.

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