A Standards-Based Digital Twin of an Experiment with a Scale Model Ship

A digital twin feasibility study (Part I): Non-deterministic predictions of fatigue life in aluminum alloy 7075-T651 using a microstructure-based multi-scale model

Engineering Fracture Mechanics ◽

10.1016/j.engfracmech.2020.106888 ◽

2020 ◽

Vol 228 ◽

pp. 106888

Author(s):

Saikumar R. Yeratapally ◽

Patrick E. Leser ◽

Jacob D. Hochhalter ◽

William P. Leser ◽

Timothy J. Ruggles

Keyword(s):

Aluminum Alloy ◽

Fatigue Life ◽

Feasibility Study ◽

Scale Model ◽

Digital Twin ◽

Multi Scale ◽

Aluminum Alloy 7075

Download Full-text

Maneuvering and Seakeeping Performance of a Generic Tug Based on Numerical Simulations

Volume 6A: Ocean Engineering ◽

10.1115/omae2020-18624 ◽

2020 ◽

Author(s):

Yingying Zheng ◽

Yuting Jin ◽

Lucas J. Yiew ◽

Allan R. Magee

Keyword(s):

Numerical Simulations ◽

Hydrodynamic Performance ◽

Scale Model ◽

Navier Stokes ◽

Published Data ◽

Real Time Control ◽

Hydrodynamic Behavior ◽

Digital Twin ◽

Time Control ◽

Seakeeping Performance

Abstract Autonomous tugs may play an important role in future ports, due to the shortage of qualified mariners. A digital twin (mathematical model incorporating a vessel’s hydrodynamic behavior and response, suitable for real-time control) would be needed for autonomous operations. Yet, partly because tugs are generally high-powered and very maneuverable compared to conventional vessels, there is little published data on the hydrodynamic performance of such vessels. As a first step in the development of the tug’s digital twin, the present work studies the maneuvering and seakeeping performance of a generic tug at model scale. Numerical simulations are performed for an approximately 1:10 scale model for standard resistance, static and dynamic captive and seakeeping cases. Reynolds-Averaged Navier-Stokes (RANS) k-ω model is employed for the simulations including the free surface through the Volume of Fluid approach. The hydrodynamic forces and moments on the tug model in the simulations of the standard resistance and the static and dynamic captive cases, as well as the tug model’s motions and the added resistance in headseas, are investigated. The simulation results provide data to build a mathematical maneuvering model for the tug based on 4-DoF MMG manoeuvring model, which serves as the digital twin in this case.

Download Full-text

A Digital Twin Approach to a Quantitative Microstructure-Property Study of Carbon Fibers through HRTEM Characterization and Multiscale FEA

Materials ◽

10.3390/ma13194231 ◽

2020 ◽

Vol 13 (19) ◽

pp. 4231

Author(s):

Rebekah Sweat ◽

Jin Gyu Park ◽

Richard Liang

Keyword(s):

Carbon Fiber ◽

Carbon Fibers ◽

Focused Ion Beam ◽

Ion Beam ◽

Scale Model ◽

X Ray ◽

Digital Twin ◽

X Ray Scattering ◽

Forms Of Carbon ◽

Ray Scattering

Microstructures of typical carbon fibers (CFs) from polyacrylonitrile (PAN) and pitch-based precursors were studied using a novel digital twin approach with individual carbon fibers for a local crystal scale model. The transmission electron microscopy (TEM) samples were prepared using a focused-ion beam (FIB) for both longitudinal and transverse directions of carbon fibers. Measurements of the crystal size and orientation were estimated from X-ray scattering. TEM imaging of graphitic packing facilitated further comprehension of associations between processing and final material properties, which could enable customization of microstructures for property targets. Then the detailed microstructural information and their X-ray scattering properties were incorporated into the simulation model of an individual carbon fiber. Assuming that graphene properties are the same among different forms of carbon fiber, a reasonable physics-based explanation for such a drastic decrease in strength is the dislocations between the graphitic units. The model reveals critical defects and uncertainty of carbon fiber microstructures, including skin/core alignment differences and propagating fracture before ultimate failure. The models are the first to quantify microstructures at the crystal scale with micromechanics and to estimate tensile and compressive mechanical properties of carbon fiber materials, as well as potentially develop new fundamental understandings for tailoring carbon fiber and composites properties.

Download Full-text

Modeling Within-Person Variance in Reaction Time Data of Older Adults

GeroPsych ◽

10.1024/1662-9647/a000045 ◽

2011 ◽

Vol 24 (4) ◽

pp. 169-176 ◽

Cited By ~ 4

Author(s):

Philippe Rast ◽

Daniel Zimprich

Keyword(s):

Reaction Time ◽

Cognitive Aging ◽

Reaction Times ◽

Reaction Time Task ◽

Reaction Time Data ◽

Scale Model ◽

Time Data ◽

Time Task ◽

The Mean ◽

Second Wave

In order to model within-person (WP) variance in a reaction time task, we applied a mixed location scale model using 335 participants from the second wave of the Zurich Longitudinal Study on Cognitive Aging. The age of the respondents and the performance in another reaction time task were used to explain individual differences in the WP variance. To account for larger variances due to slower reaction times, we also used the average of the predicted individual reaction time (RT) as a predictor for the WP variability. Here, the WP variability was a function of the mean. At the same time, older participants were more variable and those with better performance in another RT task were more consistent in their responses.

Download Full-text

Using the Rating Scale Model to Examine the Psychometric Properties of the Self-Efficacy Scale for Driver Competence

European Journal of Psychological Assessment ◽

10.1027/1015-5759/a000063 ◽

2011 ◽

Vol 27 (3) ◽

pp. 164-170 ◽

Cited By ~ 1

Author(s):

Anna Sundström

Keyword(s):

Psychometric Properties ◽

Self Efficacy ◽

Rating Scale ◽

Measurement Precision ◽

The Self ◽

Test Theory ◽

Self Report ◽

Scale Model ◽

Validity And Reliability ◽

Two Samples

This study evaluated the psychometric properties of a self-report scale for assessing perceived driver competence, labeled the Self-Efficacy Scale for Driver Competence (SSDC), using item response theory analyses. Two samples of Swedish driving-license examinees (n = 795; n = 714) completed two versions of the SSDC that were parallel in content. Prior work, using classical test theory analyses, has provided support for the validity and reliability of scores from the SSDC. This study investigated the measurement precision, item hierarchy, and differential functioning for males and females of the items in the SSDC as well as how the rating scale functions. The results confirmed the previous findings; that the SSDC demonstrates sound psychometric properties. In addition, the findings showed that measurement precision could be increased by adding items that tap higher self-efficacy levels. Moreover, the rating scale can be improved by reducing the number of categories or by providing each category with a label.

Download Full-text

An IRT Investigation of the Validity of Non-Patient Analogue Research Using the Beck Depression Inventory

European Journal of Psychological Assessment ◽

10.1027/1015-5759.11.1.14 ◽

1995 ◽

Vol 11 (1) ◽

pp. 14-20 ◽

Cited By ~ 22

Author(s):

Sean M. Hammond

Keyword(s):

Differential Item Functioning ◽

Beck Depression Inventory ◽

Rating Scale ◽

Latent Trait ◽

Scale Model ◽

Item Functioning ◽

Two Samples ◽

Patient Groups ◽

Analogue Research ◽

Rating Scale Model

This paper presents an IRT analysis of the Beck Depression Inventory which was carried out to assess the assumption of an underlying latent trait common to non-clinical and patient samples. A one parameter rating scale model was fitted to data drawn from a patient and non-patient sample. Findings suggest that while the BDI fits the model reasonably well for the two samples separately there is sufficient differential item functioning to raise serious duobts of the viability of using it analogously with patient and non-patient groups.

Download Full-text

Modeling Intraindividual Variability in Three-Level Multilevel Models

Methodology ◽

10.1027/1614-2241/a000150 ◽

2018 ◽

Vol 14 (3) ◽

pp. 95-108 ◽

Cited By ~ 4

Author(s):

Steffen Nestler ◽

Katharina Geukes ◽

Mitja D. Back

Keyword(s):

Multilevel Model ◽

Multilevel Models ◽

Mixed Effects ◽

Repeated Measurements ◽

Scale Model ◽

Suggested Approach ◽

Psychological Study ◽

Level Data ◽

Ecological Momentary ◽

Momentary Assessment

Abstract. The mixed-effects location scale model is an extension of a multilevel model for longitudinal data. It allows covariates to affect both the within-subject variance and the between-subject variance (i.e., the intercept variance) beyond their influence on the means. Typically, the model is applied to two-level data (e.g., the repeated measurements of persons), although researchers are often faced with three-level data (e.g., the repeated measurements of persons within specific situations). Here, we describe an extension of the two-level mixed-effects location scale model to such three-level data. Furthermore, we show how the suggested model can be estimated with Bayesian software, and we present the results of a small simulation study that was conducted to investigate the statistical properties of the suggested approach. Finally, we illustrate the approach by presenting an example from a psychological study that employed ecological momentary assessment.

Download Full-text