On the Measurement of Creep by Nanoindentation with Continuous Stiffness Techniques

2004 ◽  
Vol 841 ◽  
Author(s):  
Andrei Rar ◽  
Sangjoon Sohn ◽  
Warren C. Oliver ◽  
David L. Goldsby ◽  
Terry E. Tullis ◽  
...  
Keyword(s):  
Time Dependence ◽  
Contact Area ◽  
Indentation Depth ◽  
Contact Stiffness ◽  
Point Of View ◽  
Hard Material ◽  
Thermal Drift ◽  
Material Creep ◽  
Creep Measurements ◽  
Using Data

ABSTRACTMeasurement of material creep parameters by means of nanoindentation using continuous stiffness techniques avoids the problems associated with thermal drift that often plague creep measurements based on the time dependence of the indentation depth alone [1, 2]. Problems with thermal drift are negligible from a practical point of view during continuous stiffness measurements because the contact stiffness can be measured over a short time period, typically less than one second, during which time the displacements due to thermal drift are minimal. Determination of the time dependence of the indentation depth from the stiffness data relies on the well-known relation between contact stiffness and the square root of the contact area. For pyramidal indenters, the true indentation contact depth must be proportional to the contact stiffness, leading to the assumption that indentation depth is also proportional to the contact stiffness. In this study, we critically examine this assumption using data obtained from experiments on a relatively soft material, epoxy, and a relatively hard material, fused quartz. The results show that just after initial load application, the change in contact area may be different than that expected from the change in indentation depth. One possible explanation for the observed behavior is examined by finite element modeling.

Analysis of the contact interactions between fingertips and objects with different surface curvatures

2005 ◽  
Vol 219 (2) ◽  
pp. 89-103 ◽  
Author(s):  
J Z Wu ◽  
R G Dong
Keyword(s):  
Contact Pressure ◽  
Contact Area ◽  
Contact Surface ◽  
Soft Tissues ◽  
Contact Stiffness ◽  
Element Model ◽  
Point Of View ◽  
Contact Interactions ◽  
Grasp Stability ◽  
Simulation Results

Previous experimental observations indicated that the contact interactions between finger and tool handle interfere with the grasp stability, affecting the comfort and manipulations of handheld tools. From a biomechanical point of view, the curvature of the contact surface should affect the contact pressure and contact area, and thereby the comfort and manipulations of hand tools. The current authors analysed, via a finite element model, the contact interactions between fingertips and objects with different curvatures. The effects of the curvature on the contact stiffness, fingertip deformations, contact pressure distributions, and stress/strain distributions within the soft tissues were analysed. The simulation results indicated that the curvature of the contact interface influences the contact characteristics significantly. For a given contact force, the contact area and the contact stiffness increase but the contact pressure and the fingertip deformation decrease with the decrease of the contact surface curvature. The present simulation results will be useful for ergonomic designers in their aim to improve the design of tool handles.

scholarly journals Determinants of Corporate Anti-Corruption Disclosure: The Case of the Emerging Economics

2021 ◽  
Vol 13 (6) ◽  
pp. 3462
Author(s):  
Maider Aldaz Odriozola ◽  
Igor Álvarez Etxeberria
Keyword(s):  
Empirical Studies ◽  
Geographical Area ◽  
Control Variable ◽  
Emerging Countries ◽  
Point Of View ◽  
Press Freedom ◽  
Negative Effects ◽  
Key Factor ◽  
Using Data ◽  
Positive Effect

Corruption is a key factor that affects countries’ development, with emerging countries being a geographical area in which it tends to generate greater negative effects. However, few empirical studies analyze corruption from the point of view of disclosure by companies in this relevant geographical area. Based on a regression analysis using data from the 96 large companies from 15 emerging countries included in the 2016 International Transparency Report, this paper seeks to understand what determinants affect such disclosure. In that context, this paper provides empirical evidence to understand the factors that influence reporting on anti-corruption mechanisms in an area of high economic importance that has been little studied to date, pointing to the positive effect of press freedom in a country where the company is located and with the industry being the unique control variable that strengthens this relationship.

scholarly journals PENERAPAN MODEL PEMBELAJARAN KOOPERATIF JIGSAW UNTUK MENINGKATKAN MOTIVASI PADA SISWA KELAS V SEKOLAH DASAR

2020 ◽  
Vol 7 (2) ◽  
pp. 56-63
Author(s):  
Bandi Usman ◽  
Khairil Akbar ◽  
Kurnia Dyah Anggorowati
Keyword(s):  
Physical Education ◽  
Student Learning ◽  
Learning Model ◽  
Point Of View ◽  
Learning Motivation ◽  
Fifth Grade ◽  
Motivation To Learn ◽  
Average Value ◽  
Fifth Grade Students ◽  
Using Data

Abstrak: This study aims to increase student learning motivation in the field of physical education, sports and health. The learning model used is the application of the learning model through cooperative jigsaw to increase learning motivation in the field of physical education, sports and healthfor fifth grade students. Classroom action research (PTK) is carriedout using data collection techniques, namely motivation tests and questionnaires. The results of this study showed that in cycle 1, the average value of student learning motivation was 73% in the motivated category but not yet complete. Then in cycle II obtained a percentage of learning motivation of 90% categorized as motivated according to the success criteria and seen from the point of view of the maximum completeness criteria (KKM) students are said to be complete. The percentage of increasing learning motivation from cycle I to cycle II was 17%. The jigsaw cooperative learning model can increase student motivation, especially in sports and health physical education subjects.Keywords: learning Model, motivation to learn physical education sports and health.Abstrak: Penelitian ini bertujuan untuk meningkatkan motivasi belajar siswa pada bidang studi Pendidikan Jasmani Olahraga dan Kesehatan. Model pembelajaran yang digunakan adalah penerapan model pembelajaran melalui kooperatif Jigsaw untuk meningkatkan motivasi belajar pada bidang studi Pendidikan Jasmani Olahraga dan Kesehatan pada siswa kelas V, dilakukan penelitian tindakan kelas (PTK) dengan teknik pengumpulan data yakni tes dan angket motivasi. Hasil penelitian ini diperoleh siklus I nilai rata-rata motivasi belajar siswa presentase sebesar 73% kategori termotivasi tetapi belum tuntas. Kemudian pada siklus II diperoleh presentase motivasi belajar sebesar 90% dikategorikan termotivasi sesuai kriteria keberhasilan dan dilihat dari sudut pandang kriteria ketuntasan maksimal (KKM) siswa sudah dikatakan tuntas. Presentase peningkatan motivasi belajar siklus I ke siklus II yaitu 17%. Model pembelajaran kooperatif jigsaw dapat meningkatkan motivasi belajar siswa, terutama pada mata pelajaran Pendidikan Jasmani Olahraga dan Kesehatan.Kata Kunci: Model Pembelajaran, Motivasi Belajar Pendidikan Jasmani Olahraga dan Kesehatan

scholarly journals Political Correlates of Apophatic and Cataphatic Listening Styles

2018 ◽  
Author(s):  
Eike Mark Rinke ◽  
Patricia Moy
Keyword(s):  
Empirical Test ◽  
National Sample ◽  
Point Of View ◽  
Sample Survey ◽  
Normative Concepts ◽  
Political Outcomes ◽  
Critical Error ◽  
Using Data ◽  
Task Oriented ◽  
And Task

While it is a truism that political voice is a cornerstone of democratic theory, less theorizing has focused on its counterpart, political listening. Drawing upon research related to listening practices, this study operationalizes for empirical study Dobson’s (2014) normative concepts of apophatic listening, which is dialogic and facilitates discussion across lines of difference, and cataphatic listening, which is monologic and disruptive in nature. Using data from a national sample survey of Latinos fielded shortly after the 2016 U.S. presidential election (N = 720), we provide an empirical test of these listening practices’ democratic value by examining how relational and analytical listening (dimensions of apophatic practices) and task-oriented and critical listening (dimensions of cataphatic practices) are associated with various political outcomes, including political interest, knowledge, trust, and participation. Findings indicate that, from a normative point of view, task-oriented listening was unrelated or negatively related to political outcomes while relational listening had ambivalent relations. However, the two cognitive-epistemic dimensions of both types of listening – analytical listening and critical (error-seeking) listening – were both strongly and positively related to most studied political outcomes. These findings offer nuanced evidence that apophatic and cataphatic listening might not necessarily be at odds with each other where democratically desirable outcomes are concerned.

scholarly journals Strategic Aspect of Knowledge Management

Organizacija ◽  
2017 ◽  
Vol 50 (2) ◽  
pp. 163-176 ◽  
Author(s):  
Olja Arsenijević ◽  
Dragan Trivan ◽  
Iztok Podbregar ◽  
Polona Šprajc
Keyword(s):  
Knowledge Management ◽  
Tacit Knowledge ◽  
First Generation ◽  
Point Of View ◽  
Factors Affecting ◽  
Level Of Knowledge ◽  
Empirical Point ◽  
Using Data ◽  
Tacit Knowledge Management

Abstract Background and Purpose: This paper analyses the strategic aspects of knowledge management in organizations in Serbia, from the theoretical and empirical point of view. In its theoretical part, the paper analyzes the latest literature in the fields of knowledge management, relations between communications strategyes and knowledge management, generations of knowledge management and organizational culture. Design/Methodology/Approach: In its empirical part, the paper deals with determining the level of knowledge management in Serbian organizations through diffrent generations of knowledge management, as well as the problem with explicit and tacit knowledge management. The hypotheses were tested using data colleted from organizatons in Serbia via questionnaire, which consisted of 50 questions to examine five key factors in knowledge management. Results: The results showed that out of 41 indicators, only eight are rated positively. Results of t-test indicate significant distinctions within factors affecting the quality of knowledge management, as well as differences in quality of explicit and tacit knowledge management, therefore they confirmed both hypotheses. Conclusion: The knowledge management projects in organizations in Serbia are initiated, as well as that belonging to the first generation of knowledge management can be defined.

scholarly journals A methodology for the professional training of the management and evaluation of HPC systems

2018 ◽  
Vol 8 (1) ◽  
pp. 68-79
Author(s):  
Jarmila Skrinarova ◽  
Adam Dudas
Keyword(s):  
Professional Training ◽  
Job Scheduling ◽  
Complex Problem ◽  
Point Of View ◽  
System Management ◽  
Specific Content ◽  
Scientific Project ◽  
Job Scheduling Problem ◽  
Using Data ◽  
New Education

Abstract The paper is motivated by critical demand for experts and scientists working in areas of mathematical modeling, simulations, big data techniques and who are familiar with management of HPC systems from user and administrator point of view. We created a new course entitled “HPC system management”. Our goal is focused on students to provide them with knowledge and understanding of complex problem of the HPC system management concerning job scheduling. Important fact is that the job scheduling problem is an NP-complete problem. Next objective of our course is to educate skilled experts, who are able to design and implement programs, scripts and models doing job management to solve specific parts of this complex problem. The course is innovative from several points of view. Our new approach lies in specific content, which is oriented to the HPC system management in contrast to existing courses, which are usually focused on development of HPC applications. Also we developed and provide new education methodology in a form of scientific project, which decomposes the complex problem into subproblems and subsequently brings together solutions to the subproblems to form united model. New education methodology is focused on generation of (pseudo-) optimal jobs schedule using data from real systems. The huge volume of used data leads to ideas and methodologies of problem solving, which are suitable for problems not solvable in polynomial time. Educational methodology also contains implementation of a job scheduling simulator. The paper presents a pilot course, in which students explore various scheduling algorithms and research their properties with the use of data gained from NorduGrid

scholarly journals Image editing-based data augmentation for illumination-insensitive background subtraction

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Dimitrios Sakkos ◽  
Edmond S. L. Ho ◽  
Hubert P. H. Shum ◽  
Garry Elvin
Keyword(s):  
Deep Learning ◽  
Pilot Study ◽  
Background Subtraction ◽  
Data Augmentation ◽  
Point Of View ◽  
Content Type ◽  
Illumination Changes ◽  
Image Appearance ◽  
Using Data ◽  
Limited Training Samples

PurposeA core challenge in background subtraction (BGS) is handling videos with sudden illumination changes in consecutive frames. In our pilot study published in, Sakkos:SKIMA 2019, we tackle the problem from a data point-of-view using data augmentation. Our method performs data augmentation that not only creates endless data on the fly but also features semantic transformations of illumination which enhance the generalisation of the model.Design/methodology/approachIn our pilot study published in SKIMA 2019, the proposed framework successfully simulates flashes and shadows by applying the Euclidean distance transform over a binary mask generated randomly. In this paper, we further enhance the data augmentation framework by proposing new variations in image appearance both locally and globally.FindingsExperimental results demonstrate the contribution of the synthetics in the ability of the models to perform BGS even when significant illumination changes take place.Originality/valueSuch data augmentation allows us to effectively train an illumination-invariant deep learning model for BGS. We further propose a post-processing method that removes noise from the output binary map of segmentation, resulting in a cleaner, more accurate segmentation map that can generalise to multiple scenes of different conditions. We show that it is possible to train deep learning models even with very limited training samples. The source code of the project is made publicly available at https://github.com/dksakkos/illumination_augmentation

Mechanical System Modelling Using Physics-Based and Data-Based Subsystems

2020 ◽  
Author(s):  
Siamak Arbatani ◽  
József Kövecses
Keyword(s):  
Mechanical System ◽  
Interaction Force ◽  
Point Of View ◽  
Training Data ◽  
System Modelling ◽  
Core Element ◽  
Interaction Forces ◽  
Force Systems ◽  
Using Data ◽  
Novel Concept

Abstract Mechanical systems have been traditionally represented using parametric physics-based models. In this work, we introduce a novel concept, in this part of the mechanical system is represented using data-based subsystem models, and the overall mechanical system model is composed of these data-based and other, physics-based subsystems. A core element is the interfacing of the subsystems, which gives rise to interaction forces. The interfacing problem is formulated in a way that makes it possible to give a general representation to the interaction forces. We demonstrate that from the point of view of the physics-based subsystems the important element is that the data-based models can represent the interaction force systems properly. The data-based subsystems are developed using deep recurrent neural networks, and the training data is generated based on simulations using the fully parametric physics-based model of the system. Such training data could also be obtained through physical experimentation.

Deterministic Contact Model of a Rough Surface Against a Flat-Layered Surface

2004 ◽  
Author(s):  
H. R. Pasaribu ◽  
D. J. Schipper
Keyword(s):  
Mechanical Properties ◽  
Rough Surface ◽  
Contact Area ◽  
Indentation Depth ◽  
Normal Load ◽  
Contact Model ◽  
Real Contact Area ◽  
Single Asperity ◽  
Real Contact ◽  
Effective Mechanical Properties

The effective mechanical properties of a layered surface vary as a function of indentation depth and the values of these properties range between the value of the layer itself and of the substrate. In this paper, a layered surface is modelled like a solid that has effective mechanical properties as a function of indentation depth by assuming that the layer is perfectly bounded to the substrate. The normal load as a function of indentation depth of sphere pressed against a flat layered surface is calculated using this model and is in agreement with the experimental results published by El-Sherbiney (1975), El-Shafei et al. (1983), Tang & Arnell (1999) and Michler & Blank (2001). A deterministic contact model of a rough surface against a flat layered surface is developed by representing a rough surface as an array of spherically shaped asperities with different radii and heights (not necessarily Gaussian distributed). Once the data of radius and height of every single asperity is obtained, one can calculate the number of asperities in contact, the real contact area and the load carried by the asperities as a function of the separation.

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