scholarly journals On monotonicity and search strategies in face-based copositivity detection algorithms

2021 ◽  
Author(s):  
B. G.-Tóth ◽  
E. M. T. Hendrix ◽  
L. G. Casado
Keyword(s):  
Research Question ◽  
Quadratic Function ◽  
Mixed Integer ◽  
Quadratic Program ◽  
Matrix Methods ◽  
Detection Algorithms ◽  
Standard Simplex ◽  
Mathematical Properties ◽  
The Face ◽  
Spatial Branch And Bound

AbstractOver the last decades, algorithms have been developed for checking copositivity of a matrix. Methods are based on several principles, such as spatial branch and bound, transformation to Mixed Integer Programming, implicit enumeration of KKT points or face-based search. Our research question focuses on exploiting the mathematical properties of the relative interior minima of the standard quadratic program (StQP) and monotonicity. We derive several theoretical properties related to convexity and monotonicity of the standard quadratic function over faces of the standard simplex. We illustrate with numerical instances up to 28 dimensions the use of monotonicity in face-based algorithms. The question is what traversal through the face graph of the standard simplex is more appropriate for which matrix instance; top down or bottom up approaches. This depends on the level of the face graph where the minimum of StQP can be found, which is related to the density of the so-called convexity graph.

Model Predictive Control for Stable Walking Using the Divergent Component of Motion with Footstep Location and Yaw Adaptation

2019 ◽  
Vol 16 (05) ◽  
pp. 1950025 ◽  
Author(s):  
Robert J. Griffin ◽  
Alexander Leonessa
Keyword(s):  
Model Predictive Control ◽  
Predictive Control ◽  
Bipedal Walking ◽  
Mixed Integer ◽  
Quadratic Program ◽  
Time Varying ◽  
Complex Environments ◽  
Control Frequency ◽  
The Face ◽  
Quadratically Constrained

This paper presents an extension of previous model predictive control (MPC) schemes for dynamic walking to the stabilization of the time-varying divergent component-of-motion (DCM). In order to address the control authority limitations caused by fixed footholds, the step positions and rotations are treated as control inputs, allowing the generation and execution of stable walking motions, both at high speeds and in the face of disturbances. The use of the time-varying DCM allows consideration of height changes on the DCM dynamics, improving the robustness of the controller over varying terrain. Footstep rotation is included to allow for better modeling of the adjustment effects on reachability for stability and navigation of complex environments. This is done by formulating a quadratically constrained mixed-integer quadratic program (MIQCQP), which, when combined with the use of the time-varying DCM to account for the effects of height changes and use of angular momentum, improves the capabilities of MPC strategies for bipedal walking. While the MIQCQP cannot be solved at the desired control frequency, a method for compensating for the DCM dynamics between solves is presented. Simulation results of fast walking over flat ground and navigating varying-height terrain is presented with the ESCHER humanoid. This is combined with experiments that recover from a variety pushes, which demonstrate the effectiveness of this approach.

Supporting the Use of Rudimentary Vocalizations

2014 ◽  
Vol 23 (3) ◽  
pp. 132-139 ◽  
Author(s):  
Lauren Zubow ◽  
Richard Hurtig
Keyword(s):  
Rett Syndrome ◽  
Visual Cues ◽  
Acoustic Analysis ◽  
Eye Gaze ◽  
Research Question ◽  
Primary Research ◽  
Multiple Modalities ◽  
Face To Face ◽  
Perceptual Judgments ◽  
The Face

Children with Rett Syndrome (RS) are reported to use multiple modalities to communicate although their intentionality is often questioned (Bartolotta, Zipp, Simpkins, & Glazewski, 2011; Hetzroni & Rubin, 2006; Sigafoos et al., 2000; Sigafoos, Woodyatt, Tuckeer, Roberts-Pennell, & Pittendreigh, 2000). This paper will present results of a study analyzing the unconventional vocalizations of a child with RS. The primary research question addresses the ability of familiar and unfamiliar listeners to interpret unconventional vocalizations as “yes” or “no” responses. This paper will also address the acoustic analysis and perceptual judgments of these vocalizations. Pre-recorded isolated vocalizations of “yes” and “no” were presented to 5 listeners (mother, father, 1 unfamiliar, and 2 familiar clinicians) and the listeners were asked to rate the vocalizations as either “yes” or “no.” The ratings were compared to the original identification made by the child's mother during the face-to-face interaction from which the samples were drawn. Findings of this study suggest, in this case, the child's vocalizations were intentional and could be interpreted by familiar and unfamiliar listeners as either “yes” or “no” without contextual or visual cues. The results suggest that communication partners should be trained to attend to eye-gaze and vocalizations to ensure the child's intended choice is accurately understood.

Predictively Coordinated Vehicle Acceleration and Lane Selection Using Mixed Integer Programming

2018 ◽  
Author(s):  
R. Austin Dollar ◽  
Ardalan Vahidi
Keyword(s):  
Autonomous Vehicle ◽  
Mixed Integer ◽  
Quadratic Program ◽  
Vehicle To Vehicle ◽  
Trip Time ◽  
Induced Travel ◽  
Vehicle Acceleration ◽  
Vehicle Technology ◽  
Rule Based Approach ◽  
Integer Quadratic Program

Autonomous vehicle technology provides the means to optimize motion planning beyond human capacity. In particular, the problem of navigating multi-lane traffic optimally for trip time, energy efficiency, and collision avoidance presents challenges beyond those of single-lane roadways. For example, the host vehicle must simultaneously track multiple obstacles, the drivable region is non-convex, and automated vehicles must obey social expectations. Furthermore, reactive decision-making may result in becoming stuck in an undesirable traffic position. This paper presents a fundamental approach to these problems using model predictive control with a mixed integer quadratic program at its core. Lateral and longitudinal movements are coordinated to avoid collisions, track a velocity and lane, and minimize acceleration. Vehicle-to-vehicle connectivity provides a preview of surrounding vehicles’ motion. Simulation results show a 79% reduction in congestion-induced travel time and an 80% decrease in congestion-induced fuel consumption compared to a rule-based approach.

Managing hazards of the make-buy decision in the face of radical technological change

2018 ◽  
Vol 118 (7) ◽  
pp. 1345-1364 ◽  
Author(s):  
Woo-Yong Park
Keyword(s):  
Technological Change ◽  
Research Question ◽  
Strategy Choice ◽  
Switching Regression ◽  
Content Type ◽  
Bicycle Industry ◽  
Moderating Factors ◽  
Sourcing Strategy ◽  
The Face ◽  
Technological Experience

Purpose The purpose of this paper is to consider the management of hazards arising from the make-buy choice in the face of radical technological change. This sourcing choice can lead to distinctive exchange and hierarchical hazards. This study’s main interest is in investigating the research question “How can firms reduce those distinctive exchange and hierarchical hazards arising from the make-buy sourcing strategy when dealing with radical technological change?” Design/methodology/approach The author develops hypotheses that the in-house retention of outsourced component knowledge will likely reduce exchange hazards arising from the buy strategy choice. And prior exploratory technological experience will likely reduce hierarchical hazards arising from the make strategy choice. The author explores the US mountain bicycle industry from 1980 to 1992 to test the developed hypotheses. For endogeneity arising from the make-buy sourcing decision, the author uses Heckman’s two-stage switching regression model. Findings The major findings are that the in-house retention of outsourced component knowledge and prior exploratory technological experience is distinctive moderating factors improving performance of a buy strategy and a make strategy, respectively. Originality/value Since the extant literature tends to focus on which of the two sourcing strategies provides the greatest performance advantages in the face of radical technological change, there is a strong implication to suggest that if a firm performs poorly with one sourcing decision, the firm should switch to an alternative one. Different from the expositions of the literature, this study elevates the understanding regarding how firms can improve the performance of their current sourcing orientation rather than whether they should switch from one sourcing strategy to another.

A Comparison of Trajectory Planning and Control Frameworks for Cooperative Autonomous Driving

2021 ◽  
Vol 143 (7) ◽  
Author(s):  
Icaro Bezerra Viana ◽  
Husain Kanchwala ◽  
Kenan Ahiska ◽  
Nabil Aouf
Keyword(s):  
Trajectory Planning ◽  
Cooperative Behavior ◽  
Autonomous Driving ◽  
General Idea ◽  
Mixed Integer ◽  
Quadratic Program ◽  
Change Scenario ◽  
Planning Problem ◽  
Lane Change ◽  
Double Lane Change

Abstract This work considers the cooperative trajectory-planning problem along a double lane change scenario for autonomous driving. In this paper, we develop two frameworks to solve this problem based on distributed model predictive control (MPC). The first approach solves a single nonlinear MPC problem. The general idea is to introduce a collision cost function in the optimization problem at the planning task to achieve a smooth and bounded collision function, and thus to prevent the need to implement tight hard constraints. The second method uses a hierarchical scheme with two main units: a trajectory-planning layer based on mixed-integer quadratic program (MIQP) computes an on-line collision-free trajectory using simplified motion dynamics, and a tracking controller unit to follow the trajectory from the higher level using the nonlinear vehicle model. Connected and automated vehicles (CAVs) sharing their planned trajectories lay the foundation of the cooperative behavior. In the tests and evaluation of the proposed methodologies, matlab-carsim cosimulation is utilized. carsim provides the high-fidelity model for the multibody vehicle dynamics. matlab-carsim conjoint simulation experiments compare both approaches for a cooperative double lane change maneuver of two vehicles moving along a one-way three-lane road with obstacles.

Finding Automated (Bot, Sensor) or Semi-Automated (Cyborg) Social Media Accounts Using Network Analysis and NodeXL Basic

2017 ◽  
pp. 383-424 ◽  
Author(s):  
Shalin Hai-Jew
Keyword(s):  
Social Media ◽  
Social Network ◽  
Social Network Analysis ◽  
Network Analysis ◽  
Research Question ◽  
Other Information ◽  
The Face ◽  
Research Findings ◽  
Levels Of Automation ◽  
Information Streams

Various research findings suggest that humans often mistake social robot (‘bot) accounts for human in a microblogging context. The core research question here asks whether the use of social network analysis may help identify whether a social media account is fully automated, semi-automated, or fully human (embodied personhood)—in the contexts of Twitter and Wikipedia. Three hypotheses are considered: that automated social media account networks will have less diversity and less heterophily; that automated social media accounts will tend to have a botnet social structure, and that cyborg accounts will have select features of human- and robot- social media accounts. The findings suggest limited ability to differentiate the levels of automation in a social media account based solely on social network analysis alone in the face of a determined and semi-sophisticated adversary given the ease of network account sock-puppetry but does suggest some effective detection approaches in combination with other information streams.

scholarly journals Cooperation in the Face of Transboundary Crisis: A Framework for Analysis

2020 ◽  
Vol 3 (3) ◽  
pp. 197-209 ◽  
Author(s):  
Donald Blondin ◽  
Arjen Boin
Keyword(s):  
European Union ◽  
Financial Crisis ◽  
Crisis Management ◽  
Research Question ◽  
Cyber Attacks ◽  
Nation State ◽  
The European Union ◽  
Environmental Threats ◽  
The Face ◽  
Crisis Responses

Abstract The nation state is discovering the limits of its crisis management capacities. The Ebola and Zika outbreaks, the financial crisis, the downing of flight MH17 over Ukraine, sinking ships overfilled with refugees, cyber-attacks, urban terrorism and existential environmental threats serve as strong reminders of the complex origins and transboundary dimensions of many contemporary crises and disasters. As these transboundary aspects of modern crises become increasingly manifest, the need for international, collaborative responses appears ever clearer. But that collaboration does not always emerge in time (or at all). Even in the European Union, which has various transboundary crisis management mechanisms in place, the willingness to initiate joint crisis responses varies. This observation prompted our research question: Why do states collaborate in response to some transboundary crises but not others? We bring together the crisis and collective action literatures to formulate a theoretical framework that can help answer this question. This article identifies crucial factors that facilitate a possible pathway toward a joint response.

Analyzing the 2000 National Election Study

2005 ◽  
Vol 13 (1) ◽  
pp. 109-111 ◽  
Author(s):  
Jake Bowers ◽  
Nancy Burns ◽  
Michael J. Ensley ◽  
Donald R. Kinder
Keyword(s):  
Research Question ◽  
National Election ◽  
Survey Nonresponse ◽  
Face To Face ◽  
National Election Study ◽  
Technical Report ◽  
Random Digit Dial ◽  
The Face ◽  
Research Questions ◽  
Election Studies

In an earlier report, two of us (Bowers and Ensley, 2003, National Election Studies Technical Report, www.umich.edu/~nes) provided a general framework for understanding the particular strategy outlined by Fogarty et al. (in this issue). Fogarty et al.'s strategy is to make the face-to-face variables more like the random digit dial (RDD) telephone variables by trimming the ends in order to reduce the variance of the face-to-face (FTF) variables. Perhaps some scholars will want the FTF variables to look like the RDD variables, but that would be a fix for a specific research question. Given the significant differences in the representativeness of the samples, the processes of survey nonresponse, and the quality and character of the responses between data taken from a National Area Probability sample in person and data taken from an RDD telephone sample, research questions involving comparisons with other years in the 50-year time series will require different remedies.

scholarly journals Evaluation of Automatic Facial Wrinkle Detection Algorithms

2020 ◽  
Vol 6 (4) ◽  
pp. 17
Author(s):  
Remah Mutasim Elbashir ◽  
Moi Hoon Yap
Keyword(s):  
Gabor Filter ◽  
Ground Truth ◽  
Jaccard Similarity ◽  
Skin Changes ◽  
Detection Algorithms ◽  
New Methods ◽  
Facial Wrinkle ◽  
Similarity Indices ◽  
The Face ◽  
Enhancement Method

Facial wrinkles (considered to be natural features) appear as people get older. Wrinkle detection is an important aspect of applications that depend on facial skin changes, such as face age estimation and soft biometrics. While existing wrinkle detection algorithms focus on forehead horizontal lines, it is necessary to develop new methods to detect all wrinkles (vertical and horizontal) on whole face. Therefore, we evaluated the performance of wrinkle detection algorithms on the whole face and proposed an enhancement technique to improve the performance. More specifically, we used 45 images of the Face Recognition Technology dataset (FERET) and 25 images of the Sudanese dataset. For ground truth annotations, the selected images were manually annotated by the researcher. The experiments showed that the method with enhancement performed better at detecting facial wrinkles when compared to the state-of-the-art methods. When evaluated on FERET, the average Jaccard similarity indices were 56.17%, 31.69% and 15.87% for the enhancement method, Hybrid Hessian Filter and Gabor Filter, respectively.

Sign in / Sign up

Export Citation Format

Share Document