scholarly journals Foveal Pit Morphology Characterization: A Quantitative Analysis of the Key Methodological Steps

Entropy ◽  
2021 ◽  
Vol 23 (6) ◽  
pp. 699
Author(s):  
David Romero-Bascones ◽  
Maitane Barrenechea ◽  
Ane Murueta-Goyena ◽  
Marta Galdós ◽  
Juan Carlos Gómez-Esteban ◽  
...  
Keyword(s):  
State Of The Art ◽  
Parameter Estimates ◽  
Human Visual Perception ◽  
The Gaze ◽  
Center Location ◽  
Geometrical Features ◽  
Foveal Center ◽  
Location Methods ◽  
Morphology Characterization ◽  
Fitting Error

Disentangling the cellular anatomy that gives rise to human visual perception is one of the main challenges of ophthalmology. Of particular interest is the foveal pit, a concave depression located at the center of the retina that captures light from the gaze center. In recent years, there has been a growing interest in studying the morphology of the foveal pit by extracting geometrical features from optical coherence tomography (OCT) images. Despite this, research has devoted little attention to comparing existing approaches for two key methodological steps: the location of the foveal center and the mathematical modelling of the foveal pit. Building upon a dataset of 185 healthy subjects imaged twice, in the present paper the image alignment accuracy of four different foveal center location methods is studied in the first place. Secondly, state-of-the-art foveal pit mathematical models are compared in terms of fitting error, repeatability, and bias. The results indicate the importance of using a robust foveal center location method to align images. Moreover, we show that foveal pit models can improve the agreement between different acquisition protocols. Nevertheless, they can also introduce important biases in the parameter estimates that should be considered.

scholarly journals A Hybrid Strategic Oscillation with Path Relinking Algorithm for the Multiobjective k-Balanced Center Location Problem

Mathematics ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 853
Author(s):  
Jesús Sánchez-Oro ◽  
Ana D. López-Sánchez ◽  
Anna Martínez-Gavara ◽  
Alfredo G. Hernández-Díaz ◽  
Abraham Duarte
Keyword(s):  
Location Problem ◽  
State Of The Art ◽  
Path Relinking ◽  
Multiobjective Evolutionary Algorithms ◽  
Demand Point ◽  
High Quality ◽  
Nondominated Solutions ◽  
Center Location ◽  
Strategic Oscillation ◽  
N Demand

This paper presents a hybridization of Strategic Oscillation with Path Relinking to provide a set of high-quality nondominated solutions for the Multiobjective k-Balanced Center Location problem. The considered location problem seeks to locate k out of m facilities in order to serve n demand points, minimizing the maximum distance between any demand point and its closest facility while balancing the workload among the facilities. An extensive computational experimentation is carried out to compare the performance of our proposal, including the best method found in the state-of-the-art as well as traditional multiobjective evolutionary algorithms.

scholarly journals Comparing the State-of-the-Art Efficient Stated Choice Designs Based on Empirical Analysis

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Li Tang ◽  
Xia Luo ◽  
Yang Cheng ◽  
Fei Yang ◽  
Bin Ran
Keyword(s):  
Discrete Choice ◽  
State Of The Art ◽  
Choice Model ◽  
Orthogonal Design ◽  
Asymptotic Variance ◽  
Parameter Estimates ◽  
Efficient Design ◽  
Stated Choice ◽  
Reliable Parameter ◽  
Efficient Data

The stated choice (SC) experiment has been generally regarded as an effective method for behavior analysis. Among all the SC experimental design methods, the orthogonal design has been most widely used since it is easy to understand and construct. However, in recent years, a stream of research has put emphasis on the so-called efficient experimental designs rather than keeping the orthogonality of the experiment, as the former is capable of producing more efficient data in the sense that more reliable parameter estimates can be achieved with an equal or lower sample size. This paper provides two state-of-the-art methods called optimal orthogonal choice (OOC) andD-efficient design. More statistically efficient data is expected to be obtained by either maximizing attribute level differences, or minimizing theD-error, a statistic corresponding to the asymptotic variance-covariance (AVC) matrix of the discrete choice model, when using these two methods, respectively. Since comparison and validation in the field of these methods are rarely seen, an empirical study is presented.D-error is chosen as the measure of efficiency. The result shows that both OOC andD-efficient design are more efficient. At last, strength and weakness of orthogonal, OOC, andD-efficient design are summarized.

scholarly journals Frame-Based Facial Expression Recognition Using Geometrical Features

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Anwar Saeed ◽  
Ayoub Al-Hamadi ◽  
Robert Niese ◽  
Moftah Elzobi
Keyword(s):  
Facial Expression ◽  
Prior Knowledge ◽  
State Of The Art ◽  
Recognition Rate ◽  
Human Interaction ◽  
Expression Recognition ◽  
Acoustic Data ◽  
Geometrical Features ◽  
Benchmark Datasets ◽  
Neutral Expression

To improve the human-computer interaction (HCI) to be as good as human-human interaction, building an efficient approach for human emotion recognition is required. These emotions could be fused from several modalities such as facial expression, hand gesture, acoustic data, and biophysiological data. In this paper, we address the frame-based perception of the universal human facial expressions (happiness, surprise, anger, disgust, fear, and sadness), with the help of several geometrical features. Unlike many other geometry-based approaches, the frame-based method does not rely on prior knowledge of a person-specific neutral expression; this knowledge is gained through human intervention and not available in real scenarios. Additionally, we provide a method to investigate the performance of the geometry-based approaches under various facial point localization errors. From an evaluation on two public benchmark datasets, we have found that using eight facial points, we can achieve the state-of-the-art recognition rate. However, this state-of-the-art geometry-based approach exploits features derived from 68 facial points and requires prior knowledge of the person-specific neutral expression. The expression recognition rate using geometrical features is adversely affected by the errors in the facial point localization, especially for the expressions with subtle facial deformations.

scholarly journals Fitting Logistic IRT Models: Small Wonder

1999 ◽  
Vol 2 ◽  
pp. 74-94 ◽  
Author(s):  
Miguel A. García-Pérez
Keyword(s):  
Item Response ◽  
State Of The Art ◽  
Logistic Function ◽  
Parameter Estimates ◽  
Data Set ◽  
Parameter Spaces ◽  
Irt Models ◽  
Best Fit ◽  
Logistic Functions ◽  
Metaphorical Interpretation

State-of-the-art item response theory (IRT) models use logistic functions exclusively as their item response functions (IRFs). Logistic functions meet the requirements that their range is the unit interval and that they are monotonically increasing, but they impose a parameter space whose dimensions can only be assigned a metaphorical interpretation in the context of testing. Applications of IRT models require obtaining the set of values for logistic function parameters that best fit an empirical data set. However, success in obtaining such set of values does not guarantee that the constructs they represent actually exist, for the adequacy of a model is not sustained by the possibility of estimating parameters. This article illustrates how mechanical adoption of off-the-shelf logistic functions as IRFs for IRT models can result in off-the-shelf parameter estimates and fits to data. The results of a simulation study are presented, which show that logistic IRT models can fit a set of data generated by IRFs other than logistic functions just as well as they fit logistic data, even though the response processes and parameter spaces involved in each case are substantially different. An explanation of why logistic functions work as they do is offered, the theoretical and practical consequences of their behavior are discussed, and a testable alternative to logistic IRFs is commented upon.

The Improved Frequency Response Function and its Effect on Modal Circle Fits

1984 ◽  
Vol 51 (3) ◽  
pp. 657-663 ◽  
Author(s):  
K. B. Elliott ◽  
L. D. Mitchell
Keyword(s):  
Frequency Response ◽  
Response Function ◽  
Frequency Response Function ◽  
System Analysis ◽  
Resonance Region ◽  
Random Excitation ◽  
Structural Parameter ◽  
Parameter Estimates ◽  
Average Percentage ◽  
Fitting Error

When structures are excited by random force excitation the circle fits of the data around resonance are usually poor. The structural parameter estimates, which result from this fit, are usually erroneous. No matter how elegant the circle or the multimodal fit, the results will be poor if the frequency response function (FRF) is a poor representation of the actual structural response. In general for the random excitation case, this is the case. The conventional fast Fourier transform (FFT) method which is used to estimate the frequency response function, is given by H1 (f) = Gxy/Gxx. This produces poor results when the coherence of the data falls in the resonance region. A drop in the coherence usually indicates noise at the input of the structure for this case. H1 (f) is quite sensitive to such noise giving erroneous estimates. This paper investigates an alternative method for computing the frequency response function, H2 (f) = Gyy/Gyx, and its impact on the accuracy of the circle fit procedure used in modal analysis. This new estimator is not sensitive to input noise like the currently used H1 (f). H2(f) provides the best estimate at or around resonance even in the presence of noise on the input signal. If one defines the average percentage fit error in the circle fit operation as 100 times the average radial deviation of the data points from the radius of the statistically fit circle divided by the fit circle radius, one can compute the circle fit accuracy for each of the proposed methods of data treatment. Typically, the percentage fitting error for H1 (f) might be 10 percent while the fitting error for H2 (f) using exactly the same data will be 0.5 percent. Thus, the proposed method eliminates long-standing system analysis errors through the use of a simple revision of the way the data are treated in the FFT processor around the resonance regions.

A Decision-Making Model for Distribution Center Location during Earthquake Responses

2012 ◽  
Vol 629 ◽  
pp. 808-814
Author(s):  
Wei Dong Tian ◽  
Hai Qiu Jiang ◽  
Hong Juan Zhou ◽  
Dan Guo ◽  
Wen Bo Li ◽  
...  
Keyword(s):  
Decision Making ◽  
Large Scale ◽  
Distribution Center ◽  
The Other ◽  
Yushu Earthquake ◽  
Earthquake Disaster ◽  
Center Location ◽  
Location Methods ◽  
Decision Making Model ◽  
Distribution Center Location

Different from the other distribution center location methods, there are new characteristics in distribution center location during earthquake disaster responses. In this paper, we investigate the factors impacting the location of distribution center during earthquake responses, and propose a decision-making model based on improved AHP framework for this issue. The improved AHP is extended to automatically calculate large scale judgment matrices by the crosstie model. This decision-making model was successfully applied in the simulation case of Yushu earthquake responses in 2010. The results show that the proposed decision-making model is reasonable.

scholarly journals iMon

2021 ◽  
Vol 5 (4) ◽  
pp. 1-26
Author(s):  
Sinh Huynh ◽  
Rajesh Krishna Balan ◽  
JeongGil Ko
Keyword(s):  
Mobile Applications ◽  
State Of The Art ◽  
Tracking System ◽  
Tracking Error ◽  
Motion Blur ◽  
Gaze Tracking ◽  
The Gaze ◽  
Previous State ◽  
Personal Productivity ◽  
Different Sources

Gaze tracking is a key building block used in many mobile applications including entertainment, personal productivity, accessibility, medical diagnosis, and visual attention monitoring. In this paper, we present iMon, an appearance-based gaze tracking system that is both designed for use on mobile phones and has significantly greater accuracy compared to prior state-of-the-art solutions. iMon achieves this by comprehensively considering the gaze estimation pipeline and then overcoming three different sources of errors. First, instead of assuming that the user's gaze is fixed to a single 2D coordinate, we construct each gaze label using a probabilistic 2D heatmap gaze representation input to overcome errors caused by microsaccade eye motions that cause the exact gaze point to be uncertain. Second, we design an image enhancement model to refine visual details and remove motion blur effects of input eye images. Finally, we apply a calibration scheme to correct for differences between the perceived and actual gaze points caused by individual Kappa angle differences. With all these improvements, iMon achieves a person-independent per-frame tracking error of 1.49 cm (on smartphones) and 1.94 cm (on tablets) when tested with the GazeCapture dataset and 2.01 cm with the TabletGaze dataset. This outperforms the previous state-of-the-art solutions by ~22% to 28%. By averaging multiple per-frame estimations that belong to the same fixation point and applying personal calibration, the tracking error is further reduced to 1.11 cm (smartphones) and 1.59 cm (tablets). Finally, we built implementations that run on an iPhone 12 Pro and show that our mobile implementation of iMon can run at up to 60 frames per second - thus making gaze-based control of applications possible.

Tourist gaze and beyond: state of the art

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
W.H.M.S. Samarathunga ◽  
Li Cheng
Keyword(s):  
State Of The Art ◽  
Qualitative Content Analysis ◽  
Future Research ◽  
Research Directions ◽  
Content Type ◽  
Tourist Gaze ◽  
The Gaze ◽  
Use Of Technology ◽  
Future Research Directions ◽  
Gaze Theory

Purpose The tourist gaze remains a key concept in tourism research. The purpose of this paper is to comprehend the theoretical and empirical development of the tourist gaze notion and its contributions to tourism knowledge, identifying potential research directions by reviewing and analyzing articles that have defined, refined and applied the concept of the tourist gaze. Design/methodology/approach The study identified 109 relevant research papers primarily through the Web of Science and Scopus databases. Google Scholar, ResearchGate.net and Academia.edu were used to capturing additional work not indexed in the key databases. Qualitative content analysis was used to map the evolution of the concept, distinguish between different perspectives and identify gaps in the tourist gaze literature. Findings This “state of the art” paper on tourist gaze outlines Foucault’s original work on gaze and power, which underpins subsequent theorization within tourism. The study identifies how the tourist gaze operates in different contexts and circumstances allowing the development of gaze theory. Importantly, the evolution of the gaze theory is presented after analyzing the knowledge gaps, the contexts in which it was used, the methodologies with which it was applied. Based on the findings, the study proposes future works of gaze with the use of technology, science, nature and social media. Originality/value This paper is among one of the first states of the art papers in tourism literature that comprehensively analyzes the works on the tourist gaze, tracing its evolution and identifying future research directions to address gaps in existing knowledge.

scholarly journals Neural Networks Trained on Natural Scenes Exhibit Gestalt Closure

2021 ◽  
Author(s):  
Been Kim ◽  
Emily Reif ◽  
Martin Wattenberg ◽  
Samy Bengio ◽  
Michael C. Mozer
Keyword(s):  
State Of The Art ◽  
Ecological Validity ◽  
Past Research ◽  
Natural Images ◽  
Natural Scenes ◽  
Human Visual Perception ◽  
Statistical Structure ◽  
Visual Elements ◽  
Complete Figure ◽  
Gestalt Laws

AbstractThe Gestalt laws of perceptual organization, which describe how visual elements in an image are grouped and interpreted, have traditionally been thought of as innate. Given past research showing that these laws have ecological validity, we investigate whether deep learning methods infer Gestalt laws from the statistics of natural scenes. We examine the law of closure, which asserts that human visual perception tends to “close the gap” by assembling elements that can jointly be interpreted as a complete figure or object. We demonstrate that a state-of-the-art convolutional neural network, trained to classify natural images, exhibits closure on synthetic displays of edge fragments, as assessed by similarity of internal representations. This finding provides further support for the hypothesis that the human perceptual system is even more elegant than the Gestaltists imagined: a single law—adaptation to the statistical structure of the environment—might suffice as fundamental.

scholarly journals Counter-Passive Coherent Locator (C-PCL)—A Method of Remote Detection of Passive Radars for Electronic Warfare Systems

Electronics ◽  
2021 ◽  
Vol 10 (14) ◽  
pp. 1625
Author(s):  
Michał Knioła ◽  
Tomasz Rogala ◽  
Zenon Szczepaniak
Keyword(s):  
State Of The Art ◽  
Remote Detection ◽  
Modern State ◽  
Proof Of Concept ◽  
Extensive Discussion ◽  
Electronic Warfare ◽  
Rf Receiver ◽  
Location Methods ◽  
Physical Features ◽  
Detection And Localization

Passive Coherent Location methods and techniques have an established position in the modern state-of-the-art radar. Inexpensive, easy to deploy and undetectable for other sensors, passive radars are growing in popularity. Due to that, a need arises to develop proper methods of any possible kind of countermeasure. In this work, a method of detection and localization of hidden PCL systems is proposed. Authors exploit certain physical features of an RF receiver in order to detect such a passive systems. Results of selected hardware measurements are presented as a proof of concept. Summarized findings are followed by an extensive discussion of conditions related with the method implementation in a real world scenarios.

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