Darcy’s Experiments and the Deviation to Nonlinear Flow Regime

2000 ◽  
Vol 122 (3) ◽  
pp. 619-625 ◽  
Author(s):  
J. L. Lage ◽  
B. V. Antohe
Keyword(s):  
Flow Regime ◽  
Additional Data ◽  
Quadratic Extension ◽  
Nonlinear Flow ◽  
Data Set ◽  
Natural Processes ◽  
Darcy Equation ◽  
Flow Through ◽  
Cubic Extension ◽  
Consistent Parameter

Many important technological and natural processes involving flow through porous media are characterized by large filtration velocity. It is important to know when the transition from the linear flow regime to the quadratic flow regime actually occurs to obtain accurate models for these processes. By interpreting the quadratic extension of the original Darcy equation as a model of the macroscopic form drag, we suggest a physically consistent parameter to characterize the transition to quadratic flow regime in place of the Reynolds number, Re. We demonstrate that an additional data set obtained by Darcy, and so far ignored by the community, indeed supports the Darcy equation. Finally, we emphasize that the cubic extension proposed in the literature, proportional to Re3 and mathematically valid only for Re≪1, is irrelevant in practice. Hence, it should not be compared to the quadratic extension experimentally observed when Re⩾O1.[S0098-2202(00)01703-X]

scholarly journals Convolutional Neural Networks Model in Premature Detection of Melanoma

2019 ◽  
Vol 8 (12S2) ◽  
pp. 6-11 ◽  
Keyword(s):  
Neural Networks ◽  
Skin Cancer ◽  
Convolutional Neural Networks ◽  
Additional Data ◽  
Data Set ◽  
Non Invasive ◽  
Convolution Filter ◽  
The University ◽  
Improved Accuracy

The objective of this research is provide to the specialists in skin cancer, a premature, rapid and non-invasive diagnosis of melanoma identification, using an image of the lesion, to apply to the treatment of a patient, the method used is the architecture contrast of Convolutional neural networks proposed by Laura Kocobinski of the University of Boston, against our architecture, which reduce the depth of the convolution filter of the last two convolutional layers to obtain maps of more significant characteristics. The performance of the model was reflected in the accuracy during the validation, considering the best result obtained, which is confirmed with the additional data set. The findings found with the application of this base architecture were improved accuracy from 0.79 to 0.83, with 30 epochs, compared to Kocobinski's AlexNet architecture, it was not possible to improve the accuracy of 0.90, however, the complexity of the network played an important role in the results we obtained, which was able to balance and obtain better results without increasing the epochs, the application of our research is very helpful for doctors, since it will allow them to quickly identify if an injury is melanoma or not and consequently treat it efficiently.

scholarly journals FerryBox data in the North Sea from 2002 to 2005

2018 ◽  
Vol 10 (3) ◽  
pp. 1729-1734 ◽  
Author(s):  
Wilhelm Petersen ◽  
Susanne Reinke ◽  
Gisbert Breitbach ◽  
Michail Petschatnikov ◽  
Henning Wehde ◽  
...  
Keyword(s):  
Daily Basis ◽  
Time Interval ◽  
Arctic Seas ◽  
Data Set ◽  
The North ◽  
The North Sea ◽  
Flow Through ◽  
Data Portal ◽  
Data Gap ◽  
Biogeochemical Parameters

Abstract. From 2002 to 2005 a FerryBox system was installed aboard two different ferries travelling between Cuxhaven (Germany) and Harwich (UK) on a daily basis. The FerryBox system is an automated flow-through monitoring system for measuring oceanographic and biogeochemical parameters installed on ships of opportunity. The variables were recorded in a time interval of 10–20 s, corresponding to a spatial resolution of about 100 m. The data set provides the parameters water temperature, salinity, dissolved oxygen and chlorophyll a fluorescence. There is a longer data gap between November 2002 and August 2003 in the time series due to a change of the vessel in October 2002. The data are available at https://doi.org/10.1594/PANGAEA.883824 (Petersen et al., 2017) and as part of the COSYNA (Coastal Observing System for Northern and Arctic Seas) data portal CODM at http://codm.hzg.de/codm (last access: September 2018) or https://doi.org/10.17616/R3K02T (Breitbach, 2018).

Nonlinear Flow Through an Anisotropic Porous Media

1995 ◽  
Vol 38 (3) ◽  
pp. 863-868
Author(s):  
A. T. Hjelmfelt Jr. ◽  
D. B. Brooker
Keyword(s):  
Porous Media ◽  
Nonlinear Flow ◽  
Anisotropic Porous Media ◽  
Flow Through

scholarly journals Estimation of Band-Tailed Pigeon Band Recovery and Population Vital Rates in Colorado, 1969–1981

2016 ◽  
Vol 7 (2) ◽  
pp. 369-376 ◽  
Author(s):  
Mark E. Seamans ◽  
Clait E. Braun
Keyword(s):  
New Mexico ◽  
Data Collection ◽  
Standard Error ◽  
Additional Data ◽  
Vital Rates ◽  
Data Set ◽  
Sierra Madre Occidental ◽  
Annual Survival ◽  
Sierra Madre ◽  
Additional Data Collection

AbstractData to inform population assessment of the Interior subspecies of band-tailed pigeon, Patagioenas fasciata fasciata (breeding range from Colorado and Utah south into Sierra Madre Occidental of Mexico), have been lacking despite substantial past banding efforts. We used a data set of more than 26,000 bandings from Colorado, with 3,500 live recaptures and 780 recoveries from the harvest of banded individuals to estimate annual survival, fidelity, and harvest rates. Most birds were harvested in Colorado (62%) followed by Mexico (18%); New Mexico (16%); Arizona (3%); and 1% or less each in California, Washington, and Utah. On average, each year 15% (range 0–30%) of surviving band-tailed pigeons did not return to Colorado. From 1969 to 1981 mean annual survival was 0.633 (standard error [SE] = 0.031) for hatch-year and 0.719 (SE = 0.016) for after-hatch-year birds, with a mean annual recovery rate of 0.015 (SE = 0.002) for hatch-year and 0.011 (SE = 0.001) for after-hatch-year birds. From 1970 to 1974, mean annual abundance of band-tailed pigeons in Colorado on 1 September was 59,911–88,290. These data provide a baseline for additional data collection for band-tailed pigeons in the range of the Interior subspecies.

Framework to characterize nonlinear flow through pervious concrete

2022 ◽  
Vol 151 ◽  
pp. 106633
Author(s):  
Sergio Tunis Martins Filho ◽  
Ricardo Pieralisi ◽  
Fábio Cunha Lofrano
Keyword(s):  
Pervious Concrete ◽  
Nonlinear Flow ◽  
Flow Through

Effect of Threshold Voltage Window and Variation of Organic Synaptic Transistor for Neuromorphic System

2021 ◽  
Vol 21 (8) ◽  
pp. 4303-4309
Author(s):  
Yeongjin Hwang ◽  
Jeong Hoon Jeon ◽  
Juhyun Lee ◽  
Jonghyuk Yoon ◽  
Felix Sunjoo Kim ◽  
...  
Keyword(s):  
Power Consumption ◽  
Threshold Voltage ◽  
Random Access ◽  
Resistive Random Access Memory ◽  
Classification Rate ◽  
Data Set ◽  
Organic Transistor ◽  
Handwritten Digit ◽  
Flow Through ◽  
Neuromorphic System

Synaptic devices, which are considered as one of the most important components of neuromorphic system, require a memory effect to store weight values, a high integrity for compact system, and a wide window to guarantee an accurate programming between each weight level. In this regard, memristive devices such as resistive random access memory (RRAM) and phase change memory (PCM) have been intensely studied; however, these devices have quite high current-level despite their state, which would be an issue if a deep and massive neural network is implemented with these devices since a large amount of current-sum needs to flow through a single electrode line. Organic transistor is one of the potential candidates as synaptic device owing to flexibility and a low current drivability for low power consumption during inference. In this paper, we investigate the performance and power consumption of neuromorphic system composed of organic synaptic transistors conducting a pattern recognition simulation with MNIST handwritten digit data set. It is analyzed according to threshold voltage (VT) window, device variation, and the number of available states. The classification accuracy is not affected by VT window if the device variation is not considered, but the current sum ratio between answer node and the rest 9 nodes varies. In contrast, the accuracy is significantly degraded as increasing the device variation; however, the classification rate is less affected when the number of device states is fewer.

The Influence of Confinement on the Hydrodynamic Characteristics of a Cylindrical Pillar Within a Microchannel

2015 ◽  
Author(s):  
John O’Connor ◽  
Jeff Punch ◽  
Nicholas Jeffers ◽  
Jason Stafford
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Flow Regime ◽  
Power Law ◽  
Open Channel ◽  
Head Loss ◽  
Heat Fluxes ◽  
Hydrodynamic Characteristics ◽  
Data Set ◽  
Number Range

Microfluidic cooling technologies for future electronic and photonic microsystems require more efficient flow configurations to improve heat transfer without a hydrodynamic penalty. Although conventional microchannel heat sinks are effective at dissipating large heat fluxes, their large pressure drops are a limiting design factor. There is some evidence in the literature that obstacles such as pillars placed in a microchannel can enhance downstream convective heat transfer with some increase in pressure drop. In this paper, measured head-loss coefficients are presented for a set of single microchannels of nominal hydraulic diameter 391μm and length 30mm, each containing a single, centrally-located cylindrical pillar covering a range of confinement ratios, β = 0.1–0.7, over a Reynolds number range of 40–1900. The increase in head-loss due to the addition of the pillar ranged from 143% to 479%, compared to an open channel. To isolate the influence of the pillar, the head-loss contribution of the open channel was extracted from the data for each pillar configuration. The data was curve-fitted to a decaying power-law relationship. High coefficients of determination were recorded with low root mean squared errors, indicating good fits to the data. The data set was surface-fitted with a power law relationship using the Reynolds number based on the cylinder diameter. This was found to collapse the data well below a Reynolds number of 425 to an accuracy of ± 20%. Beyond this Reynolds number an inflection point was observed, indicating a change in flow regime similar to that of a cylinder in free flow. This paper gives an insight into the hydrodynamic behavior of a microchannel containing cylindrical pillars in a laminar flow regime, and provides a practical tool for determining the head-loss of a configuration that has been demonstrated to improve downstream heat transfer in microchannels.

Methane Diffusion in a Porous Environment

2014 ◽  
Vol 353 ◽  
pp. 50-55 ◽  
Author(s):  
Pavel Staša ◽  
Vladimír Kohut ◽  
Oldřich Kodym ◽  
Zora Jančíková
Keyword(s):  
Fluid Dynamics ◽  
Geometric Model ◽  
Water Layer ◽  
Mining Activities ◽  
Natural Processes ◽  
First Case ◽  
Flow Through ◽  
Methane Diffusion ◽  
The Given ◽  
Methane Flow

The paper deals with modeling and simulation of methane flow through the porous environment using the CFD (Computational Fluid Dynamics) software Fluent. We compare three situations, which can occur in areas, where mining activities were closed few years ago, in this article. First case is modeling of methane flow through the rocks. Second event is situation where the thin water layer is situated at the surface. The last one is occurrence of groundwater. The article responds to the need for knowledge of natural processes in the given area and it follows our previous papers [1], [2]. Software Gambit was used for creating a geometric model of the working area, for modeling the flow of gas it was used CFD software, Fluent from ANSYS, Inc..

scholarly journals On the Transition From Creeping to Inertial Flow in Arrays of Cylinders

2010 ◽  
Author(s):  
K. Yazdchi ◽  
S. Srivastava ◽  
S. Luding
Keyword(s):  
Porous Media ◽  
Darcy’S Law ◽  
Computational Study ◽  
Darcy's Law ◽  
Natural Processes ◽  
Inertial Flow ◽  
Flow Through ◽  
High Reynolds ◽  
An Array Of Cylinders ◽  
Element Method

Many important natural processes involving flow through porous media are characterized by large filtration velocity. Therefore, it is important to know when the transition from viscous to the inertial flow regime actually occurs in order to obtain accurate models for these processes. In this paper, a detailed computational study of laminar and inertial, incompressible, Newtonian fluid flow across an array of cylinders is presented. Due to the non-linear contribution of inertia to the transport of momentum at the pore scale, we observe a typical departure from Darcy’s law at sufficiently high Reynolds number (Re). Our numerical results show that the weak inertia correction to Darcy’s law is not a square or a cubic term in velocity, as it is in the Forchheimer equation. Best fitted functions for the macroscopic properties of porous media in terms of microstructure and porosity are derived and comparisons are made to the Ergun and Forchheimer relations to examine their relevance in the given porosity and Re range. The results from this study can be used for verification and validation of more advanced models for particle fluid interaction and for the coupling of the discrete element method (DEM) with finite element method (FEM).

A METHODICAL APPROACH TO CRITICAL WELL RE- EVALUATION

1989 ◽  
Vol 29 (1) ◽  
pp. 269
Author(s):  
R.J. Willink
Keyword(s):  
Additional Data ◽  
Oil And Gas ◽  
Limited Data ◽  
Case Histories ◽  
Data Set ◽  
Apparent Lack ◽  
Methodical Approach ◽  
Negative Effect ◽  
New Ideas ◽  
Petroleum Wells

A review of existing petroleum wells in a particular basin of interest is commonly the first step in acreage evaluation and prospect identification. A rigorous assessment to determine whether a well's prospect was fully evaluated must be methodical and must incorporate reviews of petrophysical, engineering, geological, seismic and economic data.Based on Australian and international case histories, comprehensive checklists of pertinent questions that should be addressed have been formulated for each of these disciplines. Some aspects questioned are broad, and obvious to the point that they can be easily overlooked. Others are more specific and subtle and require close consultation with experts. The greatest value of these checklists' documentation is their potential as a guide for the comparatively inexperienced petroleum explorationist.Implicit in critical well re- evaluation is the need to be open minded, commencing on the premise that previous interpretations are not necessarily valid today. It should be appreciated that the first interpretation of an existing well was based on a limited data set of observations strongly influenced by the geological model in favour at the time and, as such, is extremely prone to change as additional data become available, as the economic environment changes or as new ideas are formulated.Experience has shown that significant, but as yet undetected, volumes of oil and gas may be present in prospects already drilled by one or more wells. Apparent lack of success in a well has often had an unjustifiably negative effect on further exploration in the area in which this well was drilled.

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