scholarly journals Critical Angle Refractometry for Lossy Media with a Priori Known Extinction Coefficient

Physics ◽  
2021 ◽  
Vol 3 (3) ◽  
pp. 569-578
Author(s):  
Spyridon Koutsoumpos ◽  
Panagiotis Giannios ◽  
Konstantinos Moutzouris
Keyword(s):  
Extinction Coefficient ◽  
Critical Angle ◽  
Incidence Angle ◽  
A Priori ◽  
Sufficient Accuracy ◽  
Independent Measurement ◽  
Reflectance Measurement ◽  
Lossy Media ◽  
Established Technique ◽  
Better Than

Critical angle refractometry is an established technique for determining the refractive index of liquids and solids. For transparent samples, the critical angle refractometry precision is limited by incidence angle resolution. For lossy samples, the precision is also affected by reflectance measurement error. In the present study, it is demonstarted that reflectance error can be practically eliminated, provided that the sample’s extinction coefficient is a priori known with sufficient accuracy (typically, better than 5%) through an independent measurement. Then, critical angle refractometry can be as precise with lossy media as with transparent ones.

From Isovist to Spatial Perception: Wayfinding in Historic Quarter

2016 ◽  
Vol 1 (3) ◽  
Author(s):  
Chih-Hung Chen ◽  
Ting-Ju Lin ◽  
Chih-Yu Chen
Keyword(s):  
Social Interactions ◽  
Spatial Perception ◽  
Publishing House ◽  
A Priori ◽  
Relative Area ◽  
Social Stimuli ◽  
Historical District ◽  
International Publishing ◽  
A Priori Analysis ◽  
Better Than

Based on the assumption that human behaviours are mainly affected by physical and animate environments, this empirical research takes the changeful and complex historical district in Tainan to observe wayfinding behaviours. An a priori analysis of the isovist fields is conducted to identify spatial characteristics. Three measures, the relative area, convexity, and circularity, are applied to scrutinize the possible stopping points, change of speed, and route choices. Accordingly, an experiment is carried out to observe spatial behaviours and different influences of social stimuli. Results show that social interactions afford groups and pairs to perform better than individual observers in wayfinding.© 2016. The Authors. Published for AMER ABRA by e-International Publishing House, Ltd., UK. Peer–review under responsibility of AMER (Association of Malaysian Environment-Behaviour Researchers), ABRA (Association of Behavioural Researchers on Asians) and cE-Bs (Centre for Environment-Behaviour Studies, Faculty of Architecture, Planning & Surveying, Universiti Teknologi MARA, MalaysiaKeywords: wayfinding; isovist; spatial perception and social stimuli; historic quarter

scholarly journals Sensorimotor priors in nonstationary environments

2013 ◽  
Vol 109 (5) ◽  
pp. 1259-1267 ◽  
Author(s):  
Devika Narain ◽  
Robert J. van Beers ◽  
Jeroen B. J. Smeets ◽  
Eli Brenner
Keyword(s):  
Environmental Variables ◽  
A Priori ◽  
Past Research ◽  
Systematic Change ◽  
Recent Experience ◽  
Environmental Variance ◽  
Adaptive Models ◽  
Priori Information ◽  
Human Nervous System ◽  
Better Than

In the course of its interaction with the world, the human nervous system must constantly estimate various variables in the surrounding environment. Past research indicates that environmental variables may be represented as probabilistic distributions of a priori information (priors). Priors for environmental variables that do not change much over time have been widely studied. Little is known, however, about how priors develop in environments with nonstationary statistics. We examine whether humans change their reliance on the prior based on recent changes in environmental variance. Through experimentation, we obtain an online estimate of the human sensorimotor prior (prediction) and then compare it to similar online predictions made by various nonadaptive and adaptive models. Simulations show that models that rapidly adapt to nonstationary components in the environments predict the stimuli better than models that do not take the changing statistics of the environment into consideration. We found that adaptive models best predict participants' responses in most cases. However, we find no support for the idea that this is a consequence of increased reliance on recent experience just after the occurrence of a systematic change in the environment.

Estimation Design Using Youla Parametrization With Automotive Applications

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Francis Assadian ◽  
Alex K. Beckerman ◽  
Jose Velazquez Alcantar
Keyword(s):  
Kalman Filtering ◽  
Feedback Stabilization ◽  
Estimation Technique ◽  
Single Input Single Output ◽  
Normal Forces ◽  
Single Output ◽  
Multiple Input ◽  
Single Input ◽  
Established Technique ◽  
Better Than

Youla parametrization is a well-established technique in deriving single-input single-output (SISO) and, to a lesser extent, multiple-input multiple-ouput (MIMO) controllers (Youla, D., Bongiorno, J. J., Jr., and Lu, C., 1974, “Singleloop Feedback-Stabilization of Linear Multivariable Dynamical Plants,” Automatica, 10(2), pp. 159–173). However, the utility of this methodology in estimation design, specifically in the framework of controller output observer (COO) (Ozkan, B., Margolis, D., and Pengov, M., 2008, “The Controller Output Observer: Estimation of Vehicle Tire Cornering and Normal Forces,” ASME J. Dyn. Syst., Meas., Control, 130(6), p. 061002), is not established. The fundamental question to be answered is as follows: is it possible to design a deterministic estimation technique using Youla paramertization with the same robust performance, or better, than well-established stochastic estimation techniques such as Kalman filtering? To prove this point, at this stage, a comparative analysis between Youla parametrization in estimation and Kalman filtering is performed through simulations only. In this paper, we provide an overview of Youla parametrization for both control and estimation design. We develop a deterministic SISO and MIMO Youla estimation technique in the framework of COO, and we investigate the utility of this method for two applications in the automotive domain.

scholarly journals Comparative Study of the Grid-Scale and Subgrid-Scale Velocity Fields - A Priori Test

1970 ◽  
Vol 30 ◽  
pp. 19-31
Author(s):  
M Ashraf Uddin ◽  
M Matiar Rahman ◽  
M Saiful Islam Mallik
Keyword(s):  
Isotropic Turbulence ◽  
A Priori ◽  
Velocity Fields ◽  
Subgrid Scale ◽  
Homogeneous Isotropic Turbulence ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Spatial Spectra ◽  
Sharp Cutoff ◽  
Better Than

Generation of grid-scale (GS) and subgrid-scale (SGS) velocity fields is performed by direct filtering of DNS (Direct Numerical Simulation) data at a low Reynolds number in homogeneous isotropic turbulence in order to assess the spectral accuracy as well as the performance of filter functions for LES (Large Eddy Simulation). The filtering is performed using three classical filter functions: Gaussian, Tophat and Sharp cutoff filters and in all three cases the results are compared with three different filter widths for LES. Comparing the distributions of GS and SGS velocities, and the decay of turbulence with those from DNS fields through out the whole calculation we have found that among the three filter functions, the performance of Sharp cutoff filter is better than that of the other two filter functions in terms of both spatial spectra and the distribution of velocities. Furthermore, it is shown that the accuracy of the filtering approach does not depend only on the filter functions but also on the filter widths for LES. GANIT J. Bangladesh Math. Soc. (ISSN 1606-3694) 30 (2010) 19-31   DOI: http://dx.doi.org/10.3329/ganit.v30i0.8499

scholarly journals The risks of mixing dependency lengths from sequences of different length

Glottotheory ◽  
2014 ◽  
Vol 5 (2) ◽  
Author(s):  
Ramon Ferrer-i-Cancho ◽  
Haitao Liu
Keyword(s):  
Null Hypothesis ◽  
Empirical Distribution ◽  
A Priori ◽  
Sentence Length ◽  
The Other ◽  
Language Research ◽  
Varying Length ◽  
Syntactic Dependency ◽  
Better Than

AbstractMixing dependency lengths from sequences of different length is a common practice in language research. However, the empirical distribution of dependency lengths of sentences of the same length differs from that of sentences of varying length. The distribution of dependency lengths depends on sentence length for real sentences and also under the null hypothesis that dependencies connect vertices located in random positions of the sequence. This suggests that certain results, such as the distribution of syntactic dependency lengths mixing dependencies from sentences of varying length, could be a mere consequence of that mixing. Furthermore, differences in the global averages of dependency length (mixing lengths from sentences of varying length) for two different languages do not simply imply a priori that one language optimizes dependency lengths better than the other because those differences could be due to differences in the distribution of sentence lengths and other factors.

scholarly journals EFFECTS OF STANDARD AND MODIFIED GRAVITY ON INTERPLANETARY RANGES

2011 ◽  
Vol 20 (02) ◽  
pp. 181-232 ◽  
Author(s):  
L. IORIO
Keyword(s):  
Initial Conditions ◽  
A Priori ◽  
Earth Planet ◽  
General Relativistic ◽  
Heliocentric Orbits ◽  
Newtonian Constant ◽  
The Impact ◽  
Very High ◽  
Better Than

We numerically investigate the impact on the two-body range of several Newtonian and non-Newtonian dynamical effects for some Earth-planet (Mercury, Venus, Mars, Jupiter, Saturn) pairs, in view of the expected cm-level accuracy in some future planned or proposed interplanetary ranging operations. The general relativistic gravitomagnetic Lense–Thirring effect should be modeled and solved for in future accurate ranging tests of Newtonian and post-Newtonian gravity, because it falls within their measurability domain. It could a priori "imprint" the determination of some of the target parameters of the tests considered. Moreover, the ring of the minor asteroids, Ceres, Pallas, Vesta (and also many other asteroids if Mars is considered) and the trans-Neptunian objects (TNOs) act as sources of nonnegligible systematic uncertainty on the larger gravitoelectric post-Newtonian signals from which it is intended to determine the parameters γ and β of the parametrized post-Newtonian (PPN) formalism with very high precision (several orders of magnitude better than the current 10-4–10-5levels). Also, other putative, nonconventional gravitational effects, like a violation of the strong equivalence principle (SEP), a secular variation of the Newtonian constant of gravitation G, and the Pioneer anomaly, are considered. The presence of a hypothetical, distant planetary-sized body X could be detectable with future high-accuracy planetary ranging. Our analysis can, in principle, be extended to future interplanetary ranging scenarios in which one or more spacecrafts in heliocentric orbits are involved. The impact of fitting the initial conditions, and of the noise in the observations, on the actual detectability of the dynamical signatures investigated, which may be partly absorbed in the estimation process, should be quantitatively addressed in further studies.

The possibility of comparing line standards of length photographically

1953 ◽  
Vol 219 (1139) ◽  
pp. 500-515 ◽  
Keyword(s):  
Standard Deviation ◽  
Sufficient Accuracy ◽  
Visual Methods ◽  
Line Position ◽  
Single Measurement ◽  
Photographic Images ◽  
Suitable Definition ◽  
Definition Of ◽  
Better Than

Line standards of length, such as metres or yards, can be compared visually using micrometer microscopes to about one in ten millions in the most precise work. It seems possible that in a photographic comparison appreciably higher precision could be attained with less labour. Photographs of the lines on some line standards have been examined with a densitometer to determine the accuracy with which the distance between two photographic images of such lines could be measured. With suitable definition of line position a single measurement of this distance should have a standard deviation corresponding to less than 0.05 μ . Provided the temperature of the bars is known with sufficient accuracy it should be possible to compare two line standards to much better than one in ten millions in less than half the time taken by present visual methods. A machine for measuring the photographs is suggested. The characteristics of photographs of some lines are given in an appendix.

Production Lots as Determinant of Paper Production Lead Time Performance

2009 ◽  
Vol 2 (4) ◽  
pp. 63-79
Author(s):  
Pekka Koskinen ◽  
Olli-Pekka Hilmola
Keyword(s):  
Supply Chain ◽  
Lead Time ◽  
A Priori ◽  
Research Work ◽  
Dynamics Simulation ◽  
Production Environment ◽  
Time Performance ◽  
Production Order ◽  
It Applications ◽  
Better Than

In this research work we are interested about connection between lead time performance, and production order size as well as in how many production lots this order was eventually produced. Based on the system dynamics simulation model, the authors got a priori assumption that production lots have in multiproduct environment better explanation power. Our empirical findings give support for this – number of production lots explain in production environment manufacturing lead time much better than production order size. Further support is gained from supply chain phases, which are analyzed similarly, but as surprise explanation power of production lots decreases, and seems to be significantly lower in more distant markets. It is interesting to note that currently used IT applications of analyzed global case company do not give real time snapshot regarding to the development of overall supply chain lead time.

scholarly journals Critical-Angle Differential Refractometry of Lossy Media: A Theoretical Study and Practical Design Issues

Instruments ◽  
2019 ◽  
Vol 3 (3) ◽  
pp. 36
Author(s):  
Koutsoumpos ◽  
Giannios ◽  
Triantis ◽  
Moutzouris
Keyword(s):  
Optical Sensors ◽  
Critical Angle ◽  
Theoretical Study ◽  
Angle Of Incidence ◽  
Multiple Reflections ◽  
Angular Acceptance ◽  
Practical Design ◽  
Lossy Medium ◽  
Lossy Media ◽  
Differential Refractometry

At a critical angle of incidence, Fresnel reflectance at an interface between a fronttransparent and a rear lossy medium exhibits sensitive dependencies on the complex refractiveindex of the latter. This effect facilitates the design of optical sensors exploiting single (or multiple)reflections inside a prism (or a parallel plate). We determine an empirical framework that capturesperformance specifications of this sensing scheme, including sensitivity, detection limit, range oflinearity and—what we define here as—angular acceptance bandwidth. Subsequently, we developan optimization protocol that accounts for all relevant optical or geometrical variables and that canbe utilized in any application.

Design and Analysis of Hard X-Ray Microscope Employing Toroidal Mirrors Working at Grazing-Incidence

2019 ◽  
Vol 34 (04) ◽  
pp. 2055010
Author(s):  
Ying Cui ◽  
Yadong Yan ◽  
Bingjing Wu ◽  
Qi Li ◽  
Junhua He
Keyword(s):  
Optical Axis ◽  
Incidence Angle ◽  
Incident Angle ◽  
Optical Design ◽  
Grazing Incidence ◽  
Imaging Diagnosis ◽  
X Ray ◽  
Imaging Characteristics ◽  
Axis Offset ◽  
Better Than

A high resolution microscope is designed for plasma hard X-ray (10–20[Formula: see text]keV) imaging diagnosis. This system consists of two toroidal mirrors, which are nearly parallel, with an angle twice that of the grazing incidence angle and a plane mirror for spectral selection and correction of optical axis offset. The imaging characteristics of single toroidal mirror and double mirrors are analyzed in detail by the optical path function. The optical design, parameter optimization, image quality simulation and analysis of the microscope are carried out. The optimized hard X-ray microscope has a resolution better than 5[Formula: see text][Formula: see text]m at 1[Formula: see text]mm object field of view. The experimental data shows that the variation of the resolution is smaller in the direction of incident angle decrease than that in the increasing direction.

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