Estimating discharge in rivers through the combined use of dimensionless isovels and point velocity measurements

2017 ◽  
Vol 48 (3) ◽  
pp. 616-633 ◽  
Author(s):  
G. Farina ◽  
S. Alvisi ◽  
M. Franchini
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Accurate Estimation ◽  
Velocity Measurements ◽  
Combined Use ◽  
Point Velocity ◽  
New Formulation ◽  
The Relationship ◽  
River Cross Section

This paper presents a procedure for estimating discharge in a river cross-section based on the combined use of dimensionless isovels and point velocity measurements. Specifically, taking the Biot–Savart law on the magnetic field induced by an electric current in a wire as their basis as already done by other researchers, the authors propose a new formulation of the relationship characterizing the effect of the wetted perimeter on the range of velocities in a cross-section in order to take explicit account of roughness, expressed by means of Manning's coefficient. Once appropriately nondimensionalized, the isoeffect contours can be read as dimensionless isovels. Assuming in situ velocity measurements are available, discharge at a cross-section can be computed using two different methods. The proposed procedure was applied to six case studies characterized by river cross-sections which differed greatly from one another. The results show that the two methods proposed for estimating discharge lead to equivalent outcomes, and in all the cases the procedure as a whole enables a sufficiently accurate estimation of discharge, even when it is based on a limited number of velocity measurements or on the measurement of maximum surface-water velocity alone.

scholarly journals Ultraviolet Absorption Cross-Sections of Ammonia at Elevated Temperatures for Nonintrusive Quantitative Detection in Combustion Environments

2021 ◽  
pp. 000370282199044
Author(s):  
Wubin Weng ◽  
Shen Li ◽  
Marcus Aldén ◽  
Zhongshan Li
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Absorption Cross Section ◽  
Elevated Temperatures ◽  
Uv Absorption ◽  
Energy Utilization ◽  
Quantitative Detection ◽  
Absorption Cross ◽  
Hot Gas

Ammonia (NH3) is regarded as an important nitrogen oxides (NOx) precursor and also as an effective reductant for NOx removal in energy utilization through combustion, and it has recently become an attractive non-carbon alternative fuel. To have a better understanding of thermochemical properties of NH3, accurate in situ detection of NH3 in high temperature environments is desirable. Ultraviolet (UV) absorption spectroscopy is a feasible technique. To achieve quantitative measurements, spectrally resolved UV absorption cross-sections of NH3 in hot gas environments at different temperatures from 295 K to 590 K were experimentally measured for the first time. Based on the experimental results, vibrational constants of NH3 were determined and used for the calculation of the absorption cross-section of NH3 at high temperatures above 590 K using the PGOPHER software. The investigated UV spectra covered the range of wavelengths from 190 nm to 230 nm, where spectral structures of the [Formula: see text] transition of NH3 in the umbrella bending mode, v2, were recognized. The absorption cross-section was found to decrease at higher temperatures. For example, the absorption cross-section peak of the (6, 0) vibrational band of NH3 decreases from ∼2 × 10−17 to ∼0.5 × 10−17 cm2/molecule with the increase of temperature from 295 K to 1570 K. Using the obtained absorption cross-section, in situ nonintrusive quantification of NH3 in different hot gas environments was achieved with a detection limit varying from below 10 parts per million (ppm) to around 200 ppm as temperature increased from 295 K to 1570 K. The quantitative measurement was applied to an experimental investigation of NH3 combustion process. The concentrations of NH3 and nitric oxide (NO) in the post flame zone of NH3–methane (CH4)–air premixed flames at different equivalence ratios were measured.

Algorithm for Determining the Statistical Properties of Cloud Particles through In Situ Ensemble Measurements

2016 ◽  
Vol 33 (9) ◽  
pp. 1985-2000
Author(s):  
Matthew Hayman
Keyword(s):  
Cross Sections ◽  
Fundamental Principle ◽  
Individual Particle ◽  
Analytical Relationship ◽  
Particle Properties ◽  
Network Bandwidth ◽  
Single Detector ◽  
The Relationship ◽  
Aircraft Data

AbstractAn algorithm is described for inverting individual particle properties from statistics of ensemble observations, thereby dispelling the notion that coincident particles create inherently erroneous data in particle probes. The algorithm assumes that the observed property obeys superposition, that the particles are independently randomly distributed in space, and that the particle distribution is stationary over the accumulation distance. The fundamental principle of the algorithm is based on a derived analytical relationship between ensemble and individual particle statistics with fully defined derivatives. This enables rapid convergence of forward inversions. Furthermore, this relationship has no dependence on the particular instrument realization, so the accuracy of the relationship is not fundamentally constrained by the accuracy to which a measurement system can be characterized or modeled. This algorithm is presented in terms of a single observed property, but the derivation is valid for correlated multiparameter retrievals. Because data are collected in histograms, this technique would require relatively little storage and network bandwidth on an aircraft data system. This statistical analysis is derived here for measuring particle geometric extinction cross sections, but it could also be applied to other particle properties, such as scattering cross-section and phase matrix elements. In this example application, a simulated beam passes through a sampled environment onto a single detector to periodically measure beam extinction. This measured extinction may be the result of one or more particles, but it is shown that the probability distribution function of the ensemble (multiparticle) extinction measurement can be used to obtain the distribution of individual particle extinction cross sections (used here as a proxy for particle size distribution).

scholarly journals The relationship between the arrangement of rays in secondary phloem and grain inclination in the wood of Pinus silyestris L. and Picea abies Karst

2014 ◽  
Vol 59 (1-4) ◽  
pp. 9-24
Author(s):  
Władysław Pyszyński
Keyword(s):  
Picea Abies ◽  
Cross Section ◽  
Cross Sections ◽  
Pinus Silvestris ◽  
Secondary Phloem ◽  
The Cross ◽  
Wood Grain ◽  
The Right ◽  
The Relationship ◽  
Wood Columns

The arrangement of rays in cross sections of secondary phloem and the wood grain on the tangential and radial surfaces of wood columns from <i>Pinus silvestris</i> and <i>Picea abies</i> was studied. It was found that in most cases the rays were slanted and deviated from the geometric radius in either the S-direction (to the left) or in the Z-direction (to the right) when the cross section of the stem was observed from above. The S-type deviation dominated in those stems in which the wood grain in the peripheral parts was of the S-type (left-oriented), whereas the deviation of rays in the Z-direction was found to dominate in those objects, in which the wood grain in the peripheral parts of the stem was of the Z-type (right-oriented).

scholarly journals Use of Nuclear Data Sensitivity and Uncertainty Analysis for the Design Preparation of the HCLL Breeder Blanket Mockup Experiment for ITER

2008 ◽  
Vol 2008 ◽  
pp. 1-5
Author(s):  
I. Kodeli
Keyword(s):  
Uncertainty Analysis ◽  
Cross Section ◽  
Cross Sections ◽  
Nuclear Data ◽  
Maximum Information ◽  
Tritium Production ◽  
Section Data ◽  
Combined Use ◽  
Deterministic Transport ◽  
The Cross

An experiment on a mockup of the test blanket module based on helium-cooled lithium lead (HCLL) concept will be performed in 2008 in the Frascati Neutron Generator (FNG) in order to study neutronics characteristics of the module and the accuracy of the computational tools. With the objective to prepare and optimise the design of the mockup in the sense to provide maximum information on the state-of-the-art of the cross-section data the mockup was pre-analysed using the deterministic codes for the sensitivity/uncertainty analysis. The neutron fluxes and tritium production rate (TPR), their sensitivity to the underlying basic cross-sections, as well as the corresponding uncertainties were calculated using the deterministic transport codes (DOORS package), the sensitivity/uncertainty code package SUSD3D, and the VITAMINJ/ COVA covariance matrix libraries. The cross-section reactions with largest contribution to the uncertainty of the calculated TPR were identified to be (n,2n) and (n,3n) reactions on lead. The conclusions of this work support the main benchmark design and suggest some modifications and improvements. In particular this study recommends the use, as far as possible, of both natural and enriched lithium pellets for the TRP measurements. The combined use is expected to provide additional and complementary information on the sensitive cross-sections.

POLARIZED AND UNPOLARIZED INCLUSIVE ELECTRON SCATTERING IN NUCLEI AND THE INCLUSIVE NEUTRINO CROSS-SECTION

1995 ◽  
Vol 04 (01) ◽  
pp. 163-179
Author(s):  
S.L. MINTZ ◽  
M. POURKAVIANI
Keyword(s):  
Cross Section ◽  
Electron Scattering ◽  
Cross Sections ◽  
Inelastic Electron ◽  
Nuclear Excitation ◽  
Scattering Cross ◽  
Neutrino Cross Section ◽  
Inclusive Electron ◽  
Scattering Cross Sections ◽  
The Relationship

The unpolarized and parity violating polarized inclusive inelastic electron scattering cross-sections are calculated for incident electrons from threshold to 100 MeV, for the 12C nucleus. The relationship between these cross-sections and the inclusive neutrino cross-section on this same nucleus is discussed. The possibility of using the parity violating polarized electron scattering interaction to obtain the average nuclear excitation is also discussed.

scholarly journals IMPROVED ANISOTROPIC LINEAR SOURCE FORMULATION FOR MULTIPHYSICS PROBLEMS

2021 ◽  
Vol 247 ◽  
pp. 03003
Author(s):  
Nicholas F. Herring ◽  
Andrew Fitzgerald ◽  
Brendan Kochunas ◽  
Thomas Downar
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Substantial Reduction ◽  
Anisotropic Scattering ◽  
Linear Source ◽  
Isotropic Source ◽  
Cross Section Dependence ◽  
New Formulation ◽  
Similar Accuracy ◽  
Multiphysics Problems

This work seeks to extend an existing formulation of the method of characteristics with linear source approximation for problems with dynamic cross sections. The previous formulation eliminated cross section dependence of precomputed coefficients for systems with an isotropic source. The method is extended to include a formulation for spatially flat anisotropic scattering that eliminates cross section dependence of precomputed coefficients without adding additional operations; increasing efficiency in multiphysics simulations where cross sections can be subject to change. The new formulation is implemented in the MPACT code and tested on two problems: 3D transport assembly calculations using MPACT’s 2D/1D method and a 3D assembly with T/H feedback using MPACT’s 2D/1D method coupled with COBRA-TF. This work demonstrates that the new linear source formulation allows for the number of mesh elements to be significantly reduced while maintaining accuracy, leading to shorter run-times for 3D cases with fixed cross sections, and substantial reduction of memory usage for 3D cases with fixed cross sections. The multiphysics calculations show similar runtimes for the same accuracy with significant reduction of memory. For similar accuracy, the method proved effective in reducingmemory usage by, on average, 30% for 3D problems and 21% for multiphysics problems.

Electrical Tomography Sensing and Dielectrophoresis in Microchannel for 3D Particle Mixing

2011 ◽  
Author(s):  
Nur Tantiyani Ali Othman ◽  
Je-Eun Choi ◽  
Masahiro Takei
Keyword(s):  
Electric Field ◽  
Cross Section ◽  
Electric Fields ◽  
Cross Sections ◽  
Electrical Tomography ◽  
Field Frequency ◽  
Particle Mixing ◽  
Measurement Plane ◽  
Electric Field Frequency ◽  
The Relationship

The present study describes the electrical tomography sensing and dielectrophoresis (DEP) force for visualize the 3D particle mixing in the microchannel system. In the presence of non-uniform electric fields generated by point microelectrodes, the dynamic distribution behaviors of a polystyrene particle and deionized water had been investigated in this system. Microchannel was fabricated with five cross sections where 12 electrodes were installed for each measurement plane. In this experiment, the relationship between electric field frequency and DEP force of particles are calculated at different electric frequencies and diameter of particles. The applied electric field intensities are E = ±1 V/mm, ±3 V/mm and ±5 V/mm while the electric field frequencies are f = 1 kHz, 10 kHz, 100 kHz and 1 MHz and the diameter of particles are 1.3μm, 1.5μm and 2.0μm are investigated in this experiment. Simultaneously, imaged by manipulating tomography sensing at cross section A, C and D and the coupled DEP forces at cross section B and D, the particles flowing had been visualized and concentrate uniformly at near the outlets. The electrical capacitances and DEP forces between the electrode pairs of the microchannel were measured and the ECT tomograms representing the particle distribution were constructed from the measured capacitance data for each cross section in microchannel.

scholarly journals Minimisation of Overestimation of River Flows in 1D- Hydrodynamic Modeling

2021 ◽  
Author(s):  
Komal Vashist ◽  
K. K. Singh
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
River Flow ◽  
Model Performance ◽  
Mean Square ◽  
Hydrodynamic Models ◽  
One Dimensional ◽  
Index Of Agreement ◽  
Error Index ◽  
River Cross Section

Abstract One-dimensional hydrodynamic models overestimate river cross-section derived from freely available SRTM DEMs. The present study aims to minimize the overestimation of river flow. DEM-extracted cross-sections obtained from 30 m and 90 m resolutions show higher elevation values than the actual river cross sections of Krishna and Bhima rivers, India. To minimize the overestimation of the river flow, DEM-extracted cross-sections are modified using known cross-section of the river. The corrections for cross sections extracted from DEM, are obtained by subtracting the DEM-derived cross-sections from a known cross-section of the river. Monsoons flows that occurred in years 2006 and 2009 in Krishna and Bhimariver have been used for modeling. The MIKE HYDRO River model performance with modified DEM-extracted cross-sections of river improves as the correlation coefficient, root mean square error, index of agreement, Nash Sutcliffe efficiency & Percentage deviation in peak (%) values are improved.

scholarly journals Three Methods for Estimating the Entropy Parameter M Based on a Decreasing Number of Velocity Measurements in a River Cross-Section

Entropy ◽  
2014 ◽  
Vol 16 (5) ◽  
pp. 2512-2529 ◽  
Author(s):  
Giulia Farina ◽  
Stefano Alvisi ◽  
Marco Franchini ◽  
Tommaso Moramarco
Keyword(s):  
Cross Section ◽  
Velocity Measurements ◽  
Entropy Parameter ◽  
River Cross Section
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