scholarly journals State of the Art Study of Influence of Bed Roughness and Alluvial Cover on Bedrock Channels and Comparisons of Existing Models with Laboratory Scale Experiments

2020 ◽  
Author(s):  
Jagriti Mishra ◽  
Takuya Inoue
Keyword(s):  
Mathematical Models ◽  
State Of The Art ◽  
Theoretical Models ◽  
Sediment Supply ◽  
Laboratory Scale ◽  
Experimental Results ◽  
Bed Topography ◽  
Bed Roughness ◽  
The Relationship ◽  
Bedrock Channels

Abstract. Several studies have implied towards the importance of bed roughness on alluvial cover, besides, several mathematical models have also been introduced to mimic the effect bed roughness may project on alluvial cover. Here, we provide a state of the art review of research exploring the relationship between alluvial cover, sediment supply and bed topography, thereby, describing various mathematical models used to analyse deposition of alluvium. In the interest of analysing the efficiency of various available mathematical models, we performed laboratory-scale experiments and compared the results with various models. Our experiments show that alluvial cover is not merely governed by increasing sediment supply, and, bed topography is an important controlling factor of alluvial cover. Testing experimental results with various theoretical models suggest a fit of certain models for a particular bed topography and inefficiency in predicting higher roughness topography. Three models efficiently predict the experimental observations, albeit their limitations which we discuss here in detail.

scholarly journals Alluvial cover on bedrock channels: applicability of existing models

2020 ◽  
Vol 8 (3) ◽  
pp. 695-716 ◽  
Author(s):  
Jagriti Mishra ◽  
Takuya Inoue
Keyword(s):  
Mathematical Models ◽  
Sediment Accumulation ◽  
Theoretical Models ◽  
Sediment Supply ◽  
Model Parameters ◽  
Hydraulic Roughness ◽  
Bed Topography ◽  
Bed Roughness ◽  
The Relationship ◽  
Bedrock Channels

Abstract. Several studies have demonstrated the importance of alluvial cover; furthermore, several mathematical models have also been introduced to predict the alluvial cover on bedrock channels. Here, we provide an extensive review of research exploring the relationship between alluvial cover, sediment supply and bed topography of bedrock channels, describing various mathematical models used to analyse the deposition of alluvium. To test one-dimensional theoretical models, we performed a series of laboratory-scale experiments with varying bed roughness under simple conditions without bar formation. Our experiments show that alluvial cover is not merely governed by increasing sediment supply and that bed roughness is an important controlling factor of alluvial cover. A comparison between the experimental results and the five theoretical models shows that (1) two simple models that calculate alluvial cover as a linear or exponential function of the ratio of the sediment supplied to the capacity of the channel produce good results for rough bedrock beds but not for smoother bedrock beds; (2) two roughness models which include changes in roughness with alluviation and a model including the probability of sediment accumulation can accurately predict alluvial cover in both rough and smooth beds; and (3), however, except for a model using the observed hydraulic roughness, it is necessary to adjust model parameters even in a straight channel without bars.

scholarly journals Saga of Superfluid Solids

Physics ◽  
2020 ◽  
Vol 2 (1) ◽  
pp. 49-66 ◽  
Author(s):  
Vyacheslav I. Yukalov
Keyword(s):  
Numerical Simulations ◽  
State Of The Art ◽  
Theoretical Models ◽  
The State ◽  
Experimental Results ◽  
Standing Problem

The article presents the state of the art and reviews the literature on the long-standing problem of the possibility for a sample to be at the same time solid and superfluid. Theoretical models, numerical simulations, and experimental results are discussed.

scholarly journals Adaptive Image Rendering Using a Nonlinear Mapping-Function-Based Retinex Model

Sensors ◽  
2019 ◽  
Vol 19 (4) ◽  
pp. 969
Author(s):  
JongGeun Oh ◽  
Min-Cheol Hong
Keyword(s):  
Light Source ◽  
State Of The Art ◽  
Contrast Ratio ◽  
Mapping Function ◽  
Experimental Results ◽  
Nonlinear Mapping ◽  
Low Light ◽  
Reconstruction Process ◽  
Image Rendering ◽  
The Relationship

This paper introduces an adaptive image rendering using a parametric nonlinear mapping-function-based on the retinex model in a low-light source. For this study, only a luminance channel was used to estimate the reflectance component of an observed low-light image, therefore halo artifacts coming from the use of the multiple center/surround Gaussian filters were reduced. A new nonlinear mapping function that incorporates the statistics of the luminance and the estimated reflectance in the reconstruction process is proposed. In addition, a new method to determine the gain and offset of the mapping function is addressed to adaptively control the contrast ratio. Finally, the relationship between the estimated luminance and the reconstructed luminance is used to reconstruct the chrominance channels. The experimental results demonstrate that the proposed method leads to the promised subjective and objective improvements over state-of-the-art, scale-based retinex methods.

Verification of Models of Personal Perception of Faces by Closed-Eye Classifier Using Histogram Correlation

2015 ◽  
Author(s):  
J. Romero ◽  
L. Diago ◽  
J. Shinoda ◽  
I. Hagiwara
Keyword(s):  
Computational Models ◽  
State Of The Art ◽  
Experimental Results ◽  
Fuzzy Rules ◽  
Data Driven ◽  
Facial Appearance ◽  
Social Decisions ◽  
Verification Of Models ◽  
The Relationship

People rapidly form impressions from facial appearance, and these impressions affect social decisions. Data-driven, computational models are the best available tools for identifying the source of such impressions. However, the computational models cannot be accepted unless they have passed the tests of validation to ascertain their credibility. In this paper, the condition of the eyes of the person is used to validate the fuzzy rules extracted from the computational models. A simple and effective classifier is proposed to evaluate the closeness of the eyes during the evaluation of a small database of portraits. The experimental results show that closed-eyes can be detected only after the proposed shift of the normalized histogram is applied. Although it is very simple, the proposed classifier can achieve better accuracy than other state of the art classifiers. The relationship between the closeness of the eyes and the evaluation of the subjects is also analyzed.

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