Specification Searches: Ad Hoc Inference with Non-Experimental Data.

Economica ◽  
1981 ◽  
Vol 48 (190) ◽  
pp. 210
Author(s):  
Jean-Francois Richard ◽  
Edward E. Leamer
Keyword(s):  
Experimental Data ◽  
Ad Hoc

scholarly journals Study of a test methodology to assess potential drift generated by air-assisted sprayers

2013 ◽  
Vol 44 (2s) ◽  
Author(s):  
Paolo Balsari ◽  
Paolo Marucco ◽  
Claudio Bozzer ◽  
Mario Tamagnone
Keyword(s):  
Experimental Data ◽  
Ad Hoc ◽  
Sustainable Use ◽  
Spray Drift ◽  
Field Crop ◽  
The European Union ◽  
Pesticide Application ◽  
Buffer Zones ◽  
Iso Standard ◽  
Test Methodology

During pesticide application spray drift may cause diffuse pollution phenomena in the environment. In the last years the European Union, through the Directive on the sustainable use of pesticides (128/2009 EC), has recommended the adoption of measures enabling to prevent spray drift. Among these measures, the adoption of buffer zones beside the sprayed fields requires to consider different widths for these no spray zones according to the amount of spray drift generated by the spraying equipment used for application. It is therefore necessary to classify the different sprayer models according to drift risk. For what concerns the sprayers used on arboreal crops, in order to make this classification in a simple and quick way as it was already proposed for the field crop sprayers (ISO FDIS 22369-3), a study was started aimed at defining a methodology to assess potential drift produced by the different sprayer models in absence of wind, using ad hoc test benches. On the basis of the positive first experimental data obtained, a first proposal for a new ISO standard methodology was prepared.

Generalized Activation Energy Spectrum Theory: A New Approach for modeling Structural Relaxation in Amorphous Solids

1993 ◽  
Vol 321 ◽  
Author(s):  
Jung H. Shin ◽  
Harry A. Atwater
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Structural Relaxation ◽  
Ad Hoc ◽  
Amorphous Solids ◽  
Nucleation Kinetics ◽  
Crystal Silicon ◽  
Time Resolved ◽  
New Approach ◽  
Kinetics Of

ABSTRACTA general approach to the dynamics of structural relaxation in amorphous solids is developed. A form of the recombination kinetics of defects is chosen which removes the ad hoc assumption made in previous theories that defects recombine only with others of identical activation energy. The generalized theory is tested quantitatively by modelling the structural relaxation of amorphous silicon, and comparing the results with the experimental data on structural relaxation. It is found that the generalized theory is necessary in order to accurately describe the time-resolved relaxation data. The generalized theory is also applied to estimate the effect of irradiation on the nucleation kinetics of crystal silicon, and is found to agree well with experimental data.

scholarly journals Abraded Glass Strength: An Ad Hoc Fitting Protocol Based on the Change of Variable Theorem

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Camilla Ferretti ◽  
Piero Ganugi ◽  
Gabriele Pisano ◽  
Francesco Zammori
Keyword(s):  
Experimental Data ◽  
Ad Hoc ◽  
Probability Distributions ◽  
Glass Strength ◽  
Innovative Method ◽  
Change Of Variable ◽  
Random Nature ◽  
Over Time ◽  
Variable Theorem ◽  
Glass Properties

This work tackles the problem of finding a suitable statistical model to describe relevant glass properties, such as the strength under tensile stress. As known, glass is a brittle material, whose strength is strictly related to the presence of microcracks on its surface. The main issue is that the number of cracks, their size, and orientation are of random nature, and they may even change over time, due to abrasion phenomena. Consequently, glass strength should be statistically treated, but unfortunately none of the known probability distributions properly fit experimental data, when measured on abraded and/or aged glass panes. Owing to these issues, this paper proposes an innovative method to analyze the statistical properties of glass. The method takes advantage of the change of variable theorem and uses an ad-hoc transforming function to properly account for the distortion, on the original probability distribution of the glass strength, induced by the abrasion process. The adopted transforming function is based on micromechanical theory, and it provides an optimal fit of the experimental data.

A structure-based model for turbulent-boundary-layer wall pressures

2010 ◽  
Vol 650 ◽  
pp. 443-478 ◽  
Author(s):  
B.-K. AHN ◽  
W. R. GRAHAM ◽  
S. A. RIZZI
Keyword(s):  
Experimental Data ◽  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Ad Hoc ◽  
Time Resolved ◽  
Number Range ◽  
Eddy Simulation ◽  
Physically Based ◽  
Physical Insight ◽  
Velocity Spectra

Practical prediction of structural vibrations due to a turbulent boundary layer currently depends on empirical representations of the unsteady wall pressures. Improvements in these representations would be greatly facilitated if a simple, physically based model were available to test ad hoc assumptions and provide rigorous interpolation of experimental data. A possible candidate is the attached-eddy model, developed from Townsend's initial ideas by Perry and co-workers in the context of turbulence velocity spectra. This approach employs the superposition of contributions from individual ‘eddies’, of varying size, to yield its predictions. It is shown here that the same methodology can be applied for wall pressures, once the field due to an eddy has been obtained via solution of the governing Poisson equation. Comparisons with large-eddy simulation and experimental data, spanning a two-decade Reynolds number range, show remarkably good agreement, given the simplicity of the model. It is concluded that this approach has the potential to provide useful physical insight and, subject to its extension to a time-resolved form, improvements to existing empirical formulations.

scholarly journals A continuum model for concrete informed by mesoscale studies

2017 ◽  
Vol 27 (10) ◽  
pp. 1451-1481 ◽  
Author(s):  
Oleg Vorobiev ◽  
Eric Herbold ◽  
Souheil Ezzedine ◽  
Tarabay Antoun
Keyword(s):  
Experimental Data ◽  
Continuum Model ◽  
Large Scale ◽  
Ad Hoc ◽  
Target Material ◽  
Model Parameters ◽  
Single Element ◽  
Deformation And Failure ◽  
Multiple Parameters ◽  
Representative Volume

The paper describes a novel computational approach to refine continuum models for penetration calculations which involves two stages. At the first stage, a trial continuum model is used to model penetration into a concrete target. Model parameters are chosen to match experimental data on penetration depth. Deformation histories are recorded at few locations in the target around the penetrator. In the second stage, these histories are applied to the boundaries of a representative volume comparable to the element size in large scale penetration simulation. Discrete-continuum approach is used to model the deformation and failure of the material within the representative volume. The same deformation histories are applied to a single element which uses the model to be improved. Continuum model may include multiple parameters or functions which cannot be easily found using experimental data. We propose using mesoscale response to constrain such parameters and functions. Such tuning of the continuum model using typical deformation histories experienced by the target material during the penetration allows us to minimize the parameter space and build better models for penetration problems which are based on physics of penetration rather than intuition and ad hoc assumptions.

Fatigue Laws via Functional Equations

2008 ◽  
Author(s):  
Navendu Patil ◽  
Pradeep Mahadevan ◽  
Anindya Chatterjee
Keyword(s):  
Experimental Data ◽  
Fatigue Life ◽  
Ad Hoc ◽  
Complex Loading ◽  
Metal Fatigue ◽  
Life Estimation ◽  
Fatigue Life Estimation ◽  
Miner’S Rule ◽  
Miner's Rule ◽  
Many Sources

In routine industrial design, fatigue life estimation is largely based on S-N curves and ad hoc cycle counting algorithms used with Miner’s rule for predicting life under complex loading. However, there are well known deficiencies of the conventional approach. Of the many cumulative damage rules that have been proposed, Manson’s Double Linear Damage Rule (DLDR) has been the most successful. Here we follow up, through comparisons with experimental data from many sources, on a new approach to empirical fatigue life estimation (‘A Constructive Empirical Theory for Metal Fatigue Under Block Cyclic Loading’, Proceedings of the Royal Society A, in press). The basic modeling approach is first described: it depends on enforcing mathematical consistency between predictions of simple empirical models that include indeterminate functional forms, and published fatigue data from handbooks. This consistency is enforced through setting up and (with luck) solving a functional equation with three independent variables and six unknown functions. The model, after eliminating or identifying various parameters, retains three fitted parameters; for the experimental data available, one of these may be set to zero. On comparison against data from several different sources, with two fitted parameters, we find that our model works about as well as the DLDR and much better than Miner’s rule. We finally discuss some ways in which the model might be used, beyond the scope of the DLDR.

Combined Momentum Theory and Simple Vortex Theory Inflow Model for Multirotor Configurations

2021 ◽  
Author(s):  
Feyyaz Guner ◽  
J. V. R. Prasad
Keyword(s):  
Experimental Data ◽  
Ad Hoc ◽  
Complex Flow ◽  
Momentum Theory ◽  
Vortex Theory ◽  
Performance Predictions ◽  
Flow Interactions ◽  
Overall Performance ◽  
And Performance ◽  
Flight Simulations

For conventional main/tail rotor helicopters, momentum theory-based inflow models are still popular for design trade studies and flight simulations. However, simple momentum theory-based inflow models are not readily applicable in design trade studies of multirotor configuration vehicles where complex flow interactions among rotors can have a significant impact on vehicle overall performance, and hence, can impact vehicle sizing. The use of empirically corrected ad hoc inflow models is not often satisfactory. In this study, momentum theory is combined with a simple vortex theory in the development of a combined momentum theory and simple vortex theory (CMTSVT) based inflow model that is readily applicable to generic multirotor configurations. The developed model is validated against some multirotor inflow models and experimental data from the literature through comparisons of inflow predictions and performance predictions for different dual-rotor configurations. Further, inflow predictions using the proposed inflow model for a partially overlapping quad-rotor configuration are presented to illustrate the significance of rotor-on-rotor flow interactions in multirotor vehicle configurations.

scholarly journals Isotope effects in N<sub>2</sub>O photolysis from first principles

2011 ◽  
Vol 11 (5) ◽  
pp. 16075-16105 ◽  
Author(s):  
J. A. Schmidt ◽  
M. S. Johnson ◽  
R. Schinke
Keyword(s):  
Experimental Data ◽  
Cross Sections ◽  
First Principles ◽  
Potential Energy Surfaces ◽  
Ad Hoc ◽  
Isotope Effects ◽  
Isotopic Fractionation ◽  
Energy Surfaces ◽  
First Time ◽  
Wavepacket Propagation

Abstract. For the first time, accurate potential energy surfaces allow N2O cross sections and isotopic fractionation spectra to be derived that are in agreement with available experimental data (without ad hoc shifting), extending knowledge to a much broader range of conditions. Absorption spectra of rare N- and O-isotopologues (15N14N16O, 14N15N16O, 15N216O, 14N217O and 14N218O) calculated using wavepacket propagation are compared to the most abundant isotopologue (14N216O). The fractionation constants as a function of wavelength and temperature are in excellent agreement with experimental data. The study shows that excitations from the 3rd excited bending state, (0,3,0), and the first combination band, (1,1,0), are important for explaining the isotope effect at wavelengths longer than 210 nm. Only a small amount of the mass independent oxygen isotope anomaly observed in atmospheric N2O samples can be explained as arising from photolysis.

Microdiffraction Patterns of Small Metallic Particles II; Theoretical Analysis

1982 ◽  
Vol 40 ◽  
pp. 668-669
Author(s):  
A. Gómez ◽  
P. Schabes-Retchkiman ◽  
M. José-Yacamán ◽  
T. Ocaña
Keyword(s):  
Experimental Data ◽  
Electron Diffraction ◽  
Theoretical Analysis ◽  
Size Range ◽  
Dynamical Theory ◽  
Metallic Particles ◽  
Splitting Effect

The splitting effect that is observed in microdiffraction pat-terns of small metallic particles in the size range 50-500 Å can be understood using the dynamical theory of electron diffraction for the case of a crystal containing a finite wedge. For the experimental data we refer to part I of this work in these proceedings.

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