The ellipsoidal form of clasts with practical applications to fabric and size analyses of fluvial gravels

1980 ◽  
Vol 17 (12) ◽  
pp. 1725-1739 ◽  
Author(s):  
Emlyn H. Koster ◽  
Brian R. Rust ◽  
Don J. Gendzwill
Keyword(s):  
Statistical Analysis ◽  
Flow Direction ◽  
Probability Distributions ◽  
Size Analysis ◽  
Shape Variation ◽  
Practical Applications ◽  
Flow Interactions ◽  
Typical Range ◽  
Plane Area ◽  
Key Parameter

The widespread assumption that most water-worn gravel clasts approximate ellipsoids is confirmed by a statistical analysis of available data. The analysis demonstrates a Gaussian distribution of V/Ve ratios, centred on unit ratio, where V is clast volume and Ve the volume of a symmetric ellipsoid with equivalent triaxial dimensions. For internally isotropic and unbroken clasts, ellipsoidal form evolves as the rounding due to abrasion reaches its final stages. There appears to be no other major control on the tendency towards ellipsoidal geometry. The ellipsoidal tendency assists the interpretation of fluvial gravel deposits, which depends greatly on accurate description of clast size and fabric.Firstly, it facilitates calculation of Ap, the plane area projected upstream by clasts, a key parameter in bed–flow interactions such as preferred fabric. Formulae are derived to calculate Ap for ellipsoidal clasts with any configuration relative to flow direction. Viewing fabric in terms of the Ap variable supports and explains earlier conclusions concerning the controls on variability of imbrication angle.Secondly, an investigation of the relative merits of six size measures as descriptors of areal trends and predictors of nominal diameter, dn, concludes that (abc)1/3(the formula for dn of an ellipsoid) is superior. Other measures, namely, a, b, c, (a + c)/2, and (a + b + c)/3, are all subject to error in proportion to the degree of shape variation. Also, since downstream fining is typically accompanied by a changing proportion of oblate, bladed, prolate, and equant forms, dn is subject to inconsistent levels of under- or overestimation. The commonly used b dimension is endorsed as an acceptable predictor of dn, but a severely overestimates dn and should be abandoned. Information on errors in size analysis is presented as nomograms in the form of contoured c/b versus b/a plots and as probability distributions based on the typical range of shape variation in fluvial gravel.

scholarly journals Statistical Analysis and Machine Learning Prediction of Fog-Caused Low-Visibility Events at A-8 Motor-Road in Spain

Atmosphere ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 679
Author(s):  
Sara Cornejo-Bueno ◽  
David Casillas-Pérez ◽  
Laura Cornejo-Bueno ◽  
Mihaela I. Chidean ◽  
Antonio J. Caamaño ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Probability Distributions ◽  
Pearson Correlation ◽  
Likelihood Method ◽  
Neural Network Approach ◽  
Event Duration ◽  
Full Characterization ◽  
Low Visibility ◽  
Learning Machine ◽  
The Impact

This work presents a full statistical analysis and accurate prediction of low-visibility events due to fog, at the A-8 motor-road in Mondoñedo (Galicia, Spain). The present analysis covers two years of study, considering visibility time series and exogenous variables collected in the zone affected the most by extreme low-visibility events. This paper has then a two-fold objective: first, we carry out a statistical analysis for estimating the fittest probability distributions to the fog event duration, using the Maximum Likelihood method and an alternative method known as the L-moments method. This statistical study allows association of the low-visibility depth with the event duration, showing a clear relationship, which can be modeled with distributions for extremes such as Generalized Extreme Value and Generalized Pareto distributions. Second, we apply a neural network approach, trained by means of the ELM (Extreme Learning Machine) algorithm, to predict the occurrence of low-visibility events due to fog, from atmospheric predictive variables. This study provides a full characterization of fog events at this motor-road, in which orographic fog is predominant, causing important traffic problems during all year. We also show how the ELM approach is able to obtain highly accurate low-visibility events predictions, with a Pearson correlation coefficient of 0.8, within a half-hour time horizon, enough to initialize some protocols aiming at reducing the impact of these extreme events in the traffic of the A-8 motor road.

Some new approaches to probability distributions

1980 ◽  
Vol 12 (04) ◽  
pp. 903-921 ◽  
Author(s):  
S. Kotz ◽  
D. N. Shanbhag
Keyword(s):  
Probability Distributions ◽  
Random Variables ◽  
Representation Theorems ◽  
Practical Applications ◽  
New Approaches ◽  
Characterization Of Distributions ◽  
Stability Theorems ◽  
Conditional Expectations

We develop some approaches to the characterization of distributions of real-valued random variables, useful in practical applications, in terms of conditional expectations and hazard measures. We prove several representation theorems generalizing earlier results, and establish stability theorems for two general characteristics introduced in this paper.

scholarly journals Guided Optical Modes in Metal-Cladded Tunable Hyperbolic Metamaterial Slab Waveguides

Crystals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 176 ◽  
Author(s):  
Marcin Kieliszczyk ◽  
Bartosz Janaszek ◽  
Anna Tyszka-Zawadzka ◽  
Paweł Szczepański
Keyword(s):  
Power Flow ◽  
Guided Waves ◽  
Flow Direction ◽  
Nonlinear Effects ◽  
Optical Signal ◽  
Infrared Range ◽  
Graphene Sheets ◽  
Hyperbolic Metamaterial ◽  
Practical Applications ◽  
Optical Modes

We have theoretically investigated metal-cladded waveguides of tunable hyperbolic metamaterial (THMM) cores, employing graphene sheets as a tunable layer, in terms of guided waves propagation over near- to mid-infrared range, following the effective medium approximation. We have proven that these subwavelength guiding structures offer a number of effects usually not found in other types of waveguides, including controllable propagation gap and number of modes, inversion of power flow direction with respect to phase velocity, TM mode propagation, and absence of the fundamental mode, which occur as a result of controlled change of the guiding layer dispersion regime. This is the first time that the above-mentioned effects are obtained with a single, voltage-controlled waveguiding structure comprising graphene sheets and a dielectric, although the presented methodology allows us to incorporate other tunable materials beyond graphene equally well. We believe that such or similar structures, feasible by means of current planar deposition techniques, will ultimately find their practical applications in optical signal processing, controlled phase matching, controlled coupling, signal modulation, or the enhancement of nonlinear effects.

CP VIOLATION IN THE B SYSTEM—A STATISTICAL ANALYSIS

1990 ◽  
Vol 05 (05) ◽  
pp. 337-347
Author(s):  
DAVID LONDON
Keyword(s):  
Statistical Analysis ◽  
Cp Violation ◽  
Standard Model ◽  
Probability Distributions ◽  
New Physics ◽  
Hadronic Decay ◽  
System A ◽  
The Standard Model ◽  
Model Predictions ◽  
Cp Asymmetries

The standard model predictions for CP violating hadronic decay asymmetries are presented in the form of probability distributions. From these distributions, it can be easily seen what the most likely values of these quantities are, which measurements would clearly be signs of new physics, and which values of the CP asymmetries would most constrain the parameters of the standard model.

On the distribution of records in a finite sequence of observations, with an application to a road traffic problem

1973 ◽  
Vol 10 (03) ◽  
pp. 556-571 ◽  
Author(s):  
Dariush Haghighi-Talab ◽  
Christopher Wright
Keyword(s):  
Experimental Observation ◽  
Road Traffic ◽  
Probability Distributions ◽  
Finite Sequence ◽  
Simple Application ◽  
Practical Applications ◽  
Record Time ◽  
Lower Records

Probability distributions relating to the number and positions of lower records in a finite sequence of observations are obtained by methods involving the permutation of ranks. Some new results, and results of earlier authors, are expressed in a form thought to be useful for direct practical applications. Expressions are also given for the distribution of the length of a ‘record run’, which consists of the observations following and including a given record either up to the next record, or, if a further record does not occur, up to the end of the sequence of observations. This quantity, whose distribution is closely related to that of the inter-record time, has a direct and simple application to road traffic leaving a signal which has been confirmed by experimental observation.

scholarly journals Statistical deprojection of galaxy pairs

2018 ◽  
Vol 614 ◽  
pp. A45 ◽  
Author(s):  
Laurent Nottale ◽  
Pierre Chamaraux
Keyword(s):  
Statistical Analysis ◽  
Probability Distribution ◽  
Physical Properties ◽  
Previous Analysis ◽  
Probability Distributions ◽  
Second Step ◽  
Line Of Sight ◽  
Mass Determination ◽  
Dynamical Parameters

Aims. The purpose of the present paper is to provide methods of statistical analysis of the physical properties of galaxy pairs. We perform this study to apply it later to catalogs of isolated pairs of galaxies, especially two new catalogs we recently constructed that contain ≈1000 and ≈13 000 pairs, respectively. We are particularly interested by the dynamics of those pairs, including the determination of their masses. Methods. We could not compute the dynamical parameters directly since the necessary data are incomplete. Indeed, we only have at our disposal one component of the intervelocity between the members, namely along the line of sight, and two components of their interdistance, i.e., the projection on the sky-plane. Moreover, we know only one point of each galaxy orbit. Hence we need statistical methods to find the probability distribution of 3D interdistances and 3D intervelocities from their projections; we designed those methods under the term deprojection. Results. We proceed in two steps to determine and use the deprojection methods. First we derive the probability distributions expected for the various relevant projected quantities, namely intervelocity vz, interdistance rp, their ratio, and the product $r_p v_z^2$, which is involved in mass determination. In a second step, we propose various methods of deprojection of those parameters based on the previous analysis. We start from a histogram of the projected data and we apply inversion formulae to obtain the deprojected distributions; lastly, we test the methods by numerical simulations, which also allow us to determine the uncertainties involved.

scholarly journals Testing roundabout capacity models: a practical aid for choosing the right one based on total capacity calculation

2020 ◽  
Vol 80 (ET.2020) ◽  
pp. 1-17
Author(s):  
Raffaele Mauro
Keyword(s):  
Probability Distributions ◽  
Specific Capacity ◽  
Traffic Demand ◽  
Practical Applications ◽  
Capacity Model ◽  
Efficiency Measures ◽  
Capacity Calculation ◽  
Total Capacity ◽  
Capacity Formulation ◽  
The Right

The determination of efficiency measures, under a known traffic demand, is a central aspect of roundabouts analysis. Many capacity formulations have been available for some time in different countries relating to different roundabout layouts. This paper refers to fifteen roundabout entry capacity models used above all in the European countries, highlighting their input requirements and their algorithm complexity. The formulations reviewed are then compared referring to a test roundabout, with a simple and widespread layout. Monte Carlo simulation have been performed considering 5,000 traffic distribution matrices for each capacity model. The results obtained are critically assessed resorting to the calculation of roundabout total capacity. The probability distributions of total capacity allow finding a model that stands out among all as an advisable choice for a suitable capacity formulation, acting as a synthesis of all those examined. This can be of considerable use in view of practical applications, for the design of efficient and safe roundabout intersections in situations in which a country-specific capacity formulation is not available.

scholarly journals A mixture-density-based tandem optimization network for on-demand inverse design of thin-film high reflectors

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Rohit Unni ◽  
Kan Yao ◽  
Xizewen Han ◽  
Mingyuan Zhou ◽  
Yuebing Zheng
Keyword(s):  
Thin Film ◽  
High Efficiency ◽  
Periodic Structures ◽  
Probability Distributions ◽  
Optimization Techniques ◽  
Training Data ◽  
Inverse Design ◽  
Practical Applications ◽  
Mixture Density ◽  
On Demand

Abstract Deep learning (DL) has emerged as a promising tool for photonic inverse design. Nevertheless, despite the initial success in retrieving spectra of modest complexity with nearly instantaneous readout, DL-assisted design methods often underperform in accuracy compared with advanced optimization techniques and have not proven competitive in handling spectra of practical usefulness. Here, we introduce a tandem optimization model that combines a mixture density network (MDN) and a fully connected (FC) network to inversely design practical thin-film high reflectors. The multimodal nature of the MDN gives access to infinite candidate designs described by probability distributions, which are iteratively sampled and evaluated by the FC network to allow for rapid optimization. We show that the proposed model can retrieve the reflectance spectra of 20-layer thin-film structures. More interestingly, it reproduces with high precision the periodic structures of high reflectors derived from physical principles, even though no such information is included in the training data. Improved designs with extended high-reflectance zones are also demonstrated. Our approach combines the high-efficiency advantage of DL with the optimization-enabled performance improvement, enabling efficient and on-demand inverse design for practical applications.

Computational Fluid Dynamics to Assess the Blade Effect of a New Savonius Rotor for Improvement of the Output Power Coefficient

2019 ◽  
Author(s):  
Takanori Matsui ◽  
Tomohiro Fukui ◽  
Koji Morinishi
Keyword(s):  
Output Power ◽  
Flow Direction ◽  
Power Coefficient ◽  
Moment Arm ◽  
Practical Applications ◽  
Savonius Rotor ◽  
Output Coefficient ◽  
The Moment ◽  
Boltzmann Method ◽  
Virtual Flux

Abstract The output power coefficient of the Savonius rotor should be improved for better practical applications. So far, new Savonius rotor has been developed to improve the minimum output coefficient by adding semi-elliptical blade. Thus, the purpose of this research is to investigate the influence of the additional semi-elliptical blade’s position on the output coefficient. Flow around the rotor was simulated by using the regularized lattice Boltzmann method. The virtual flux method was used to express the shape of the rotor on a Cartesian grid, and the multi-block method was used for local fine grids of the rotor. The rotation speed of the Savonius rotor was maintained constant, and its performance was evaluated by the output power and torque coefficients. As a result, the semi-elliptical blade successfully generated additional positive torque in the range of the advancing phase and improved the minimum output power coefficient of the rotor during a cycle. When the moment arm is short, the semi-elliptical blade did not generate large negative torque in the range of the returning phase owing to its position behind the main blade in the wind flow direction. The output power coefficient of the new Savonius rotor was improved compared to that of the traditional one depending on the length of the semi-elliptical blade’s moment arm.

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