scholarly journals Self-Excited Acoustical Measurement System for Rock Mass Stress Mapping

Sensors ◽  
2021 ◽  
Vol 21 (20) ◽  
pp. 6749
Author(s):  
Krzysztof Lalik ◽  
Ireneusz Dominik ◽  
Krzysztof Skrzypkowski ◽  
Waldemar Korzeniowski ◽  
Krzysztof Zagórski
Keyword(s):  
Rock Mass ◽  
Measurement System ◽  
The Self ◽  
Equivalent Model ◽  
Excited System ◽  
Mine Excavation ◽  
Stress Mapping ◽  
Preliminary Study ◽  
Two Degree Of Freedom ◽  
Actual Stress

This paper presents the results of a preliminary study of a self-excited acoustical system (SAS) for nondestructive testing (NDT). The SAS system was used for mine excavation stresses examination. The principle of operation of the SAS system based on the elastoacoustical effect is presented. A numerical analysis of the excavation was carried out considering the stress factor. An equivalent model based on a two-degree-of-freedom system with a delay has been developed. This model allowed to determine the relation which relates the frequency of the self-excited system to the stress level in the studied ceiling section. This relationship is defined by the elastoacoustic coefficient. The test details for anchorages in laboratory conditions and Wieliczka Salt Mine were presented. This research details of a method for creating actual stress maps in the ceiling of a mine excavation. The results confirmed the possibility of using the new measurement system to monitor the state of stresses in the rock mass.

PRELIMINARY STUDY ON NOVEL BEAM-TO-COLUMN CONNECTION BASED ON SMA PLATE

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Michael CH Yam ◽  
Ke Ke ◽  
Ping Zhang ◽  
Qingyang Zhao
Keyword(s):  
Friction Coefficient ◽  
Energy Dissipation ◽  
Numerical Study ◽  
Numerical Models ◽  
Numerical Technique ◽  
The Self ◽  
Hysteretic Behavior ◽  
The Novel ◽  
Energy Dissipation Capacity ◽  
Preliminary Study

A novel beam-to-column connection equipped with shape memory alloy (SMA) plates has been proposed to realize resilient performance under low-to-medium seismic actions. In this conference paper, the detailed 3D numerical technique calibrated by the previous paper is adopted to examine the hysteretic behavior of the novel connection. A parametric study covering a reasonable range of parameters including the thickness of the SMA plate, friction coefficient between SMA plate and beam flange and pre-load of the bolt was carried out and the influence of the parameters was characterized. In addition, the effect of the SMA Belleville washer on the connection performance was also studied. The results of the numerical study showed that the initial connection stiffness and the energy-dissipation capacity of the novel connection can be enhanced with the increase of the thickness of the SMA plate. In addition, the initial connection stiffness and energy-dissipation behavior of the novel connection can be improved by increasing the friction coefficient or pre-load of bolts, whereas the increased friction level could compromise the self-centering behavior of the connection. The hysteretic curves of the numerical models of the connection also implied that the SMA washers may contribute to optimizing the connection behavior by increasing the connection stiffness and energy-dissipation capacity without sacrificing the self-centering behavior.

The Role of Witnesses in Humiliation: Why Does the Presence of an Audience Facilitate Humiliation Among Victims of Devaluation?

2021 ◽  
pp. 014616722110530
Author(s):  
Saulo Fernández ◽  
Tamar Saguy ◽  
Elena Gaviria ◽  
Rut Agudo ◽  
Eran Halperin
Keyword(s):  
Moderating Effect ◽  
The Self ◽  
The Other ◽  
Recall Method ◽  
Preliminary Study ◽  
Event Recall

We examined the role that witnesses play in triggering humiliation. We hypothesized that witnesses trigger humiliation because they intensify the two core appraisals underlying humiliation: unfairness and internalization of a devaluation of the self. However, we further propose that witnesses are not a defining characteristic of humiliating situations. Results of a preliminary study using an event-recall method confirmed that witnesses were as characteristic of humiliating episodes as of those that elicited shame or anger. In Experiments 1 and 2, we manipulated the presence (vs. absence) of witnesses when a professor devalued participants and the hostile tone of this devaluation. As hypothesized, in both experiments, witnesses indirectly increased humiliation via the appraisal of unfairness. Results of Experiment 2 revealed that the presence of witnesses also interacted with hostility, enhancing humiliation. As expected, this moderating effect occurred via the other key appraisal of humiliation (i.e., internalization).

Cause of a Crisis

2020 ◽  
pp. 235-252
Author(s):  
Jonathan J. Felix
Keyword(s):  
Higher Education ◽  
Trinidad And Tobago ◽  
Higher Education Institutions ◽  
Mission Statements ◽  
The Self ◽  
Current Crisis ◽  
Commercial Activity ◽  
21St Century Education ◽  
Current State ◽  
Preliminary Study

From the 1990s until the present, there has been a growing movement in the higher education sector worldwide, emphasizing the primacy of the natural sciences and commercial activity as an important part of 21st century education and workforce preparation. Since then, the ongoing discourse on higher education has also systematically led to the marginalization of humanities. This chapter explores the ways in which the statements of purpose of higher education institutions, and their subsequent activities, might contribute toward the current state of the humanities. The author argues that the self-perception of these entities is related to their organizational identity, values, and actions. Using discourse analysis, this work will also attempt to explore the mission statements of 15 major higher education institutions in Trinidad and Tobago, and how statements regarding their core work are related to the current crisis with the humanities. From this preliminary study, higher education providers may be able to reconsider the ways in which their core internal and market-driven activities might severely compromise their ability to adequately serve students and the wider society by extension.

scholarly journals Self-potential response characteristics of red sandstone samples under uniaxial compression

2019 ◽  
Vol 16 (4) ◽  
pp. 742-752
Author(s):  
Cai Yang ◽  
Shengdong Liu ◽  
Haiping Yang
Keyword(s):  
Rock Mass ◽  
Uniaxial Compression ◽  
Inflection Point ◽  
Radial Direction ◽  
The Self ◽  
Potential Difference ◽  
Potential Response ◽  
Red Sandstone ◽  
Response Characteristics ◽  
Self Potential

Abstract Deformation and rupture of rock mass under loading cause the variation of electric potential. Response characteristics of self-potential and stress during the complete stress-strain process of red sandstones play an important role in evaluating the stress state of sandstone on the basis of self-potential. Experimental results demonstrate that the stress of red sandstone under uniaxial compression is linearly correlated with the self-potential difference before the first inflection point in the initial stage of loading. The average variation rate of self-potential difference and stress is 0.1325 mV MPa−1. As the loading pressure gradually increases and enters the softening stage (before the maximum loading point), the catastrophic points of uniaxial loading stress correspond to the inflection point of self-potential. The self-potential of red sandstone varies in a range of 0–45.6 mV in that case and it fluctuates most significantly around the maximum loading point, with a range of 0.3–195.5 mV. In the end stage of loading, the macroscopic rupture of the red sandstone sample is complete, the self-potential of red sandstone fluctuates slightly around the maximum load point and then gradually stabilizes. Moreover, it is found that self-potentials change more significantly in the radial direction than in the axial direction in the uniaxial compression experiment, indicating that self-potentials generated by rock mass rupture are more sensitive in the radial direction. The rupture process of red sandstone can be dynamically represented by the tempo-spatial evolution profiles of self-potential.

Threshold of Multiple Stick-Slip Chaos for an Archetypal Self-Excited SD Oscillator Driven by Moving Belt Friction

2017 ◽  
Vol 27 (01) ◽  
pp. 1750009 ◽  
Author(s):  
Z. X. Li ◽  
Q. J. Cao ◽  
A. Léger
Keyword(s):  
Multiple Solutions ◽  
Coulomb Friction ◽  
Homoclinic Orbits ◽  
The Self ◽  
External Excitation ◽  
Stick Slip ◽  
Sd Oscillator ◽  
Excited System ◽  
Analytical Expressions ◽  
Natural Characteristics

In this paper, we investigate the multiple stick-slip chaotic motion of an archetypal self-excited smooth and discontinuous (SD) oscillator driven by moving belt friction, which is constructed with the SD oscillator and the classical moving belt. The friction force between the mass and the belt is modeled as a Coulomb friction for this system. The energy introduction or dissipation during the slip and stick modes in the system is analyzed. The analytical expressions of homoclinic orbits of the unperturbed SD oscillator are derived by using a special coordinate transformation without any pronominal truncation to retain the natural characteristics, which allows us to utilize the Melnikov’s method to obtain the chaotic thresholds of the self-excited SD oscillator in the presence of the damping and external excitation. Numerical simulations are carried out to demonstrate the multiple stick-slip dynamics of the system, which show the efficiency of the prediction for stick-slip chaos of the perturbed self-excited system. The results presented herein this paper demonstrate the complicated dynamics of stick-slip periodic solutions, multiple stick-slip chaotic solutions and also coexistence of multiple solutions for the perturbed self-excited SD oscillator.

Two-degree-of-freedom displacement measurement system based on double diffraction gratings

2016 ◽  
Vol 27 (7) ◽  
pp. 074012 ◽  
Author(s):  
Zhengang Lu ◽  
Peipei Wei ◽  
Chaoqun Wang ◽  
Jialei Jing ◽  
Jiubin Tan ◽  
...  
Keyword(s):  
Measurement System ◽  
Diffraction Gratings ◽  
Degree Of Freedom ◽  
Displacement Measurement ◽  
Double Diffraction ◽  
Two Degree Of Freedom

Research on High Bandwidth Rogowski Coil for Measuring Lightning Traveling Wave Current on Double Circuit Transmission Line

2014 ◽  
Vol 986-987 ◽  
pp. 1558-1564
Author(s):  
Cheng Ju Yang ◽  
Cheng Wei Zhang ◽  
Geng Bin Zhang ◽  
Pei Ling Chen ◽  
Shi Jun Xie
Keyword(s):  
Transmission Line ◽  
Traveling Wave ◽  
High Frequency ◽  
Power Grid ◽  
Low Frequency ◽  
Rogowski Coil ◽  
The Self ◽  
Equivalent Model ◽  
High Bandwidth ◽  
Frequency Components

Double circuit transmission line is an important part of the power grid, which is vulnerable to lightning and may endanger the security and stability of the power grid. In order to design a sensor which can monitor the lightning traveling wave current on double circuit transmission line, simulations of lightning on the double circuit transmission line were conducted. The simulation result shows that besides high frequency components, the traveling wave contains a lot of low frequency components. Based on the equivalent model and the frequency response of the self-integrated Rogowski coil, it turns out that the widely used self-integrated Rogowski coil is not suitable for this application as the problem of low frequency distortion. In this paper, through theoretical analysis and simulations in Matlab, an improved Rogowski coil with analog integrator is proposed which can correct the low frequency distortion of the self-integrated Rogowski coil. All the simulations, experiments and operating data installed to a double circuit transmission line in China verify the validity of the high bandwidth Rogowski coil.

scholarly journals Repeatability of WalkinSense® in shoe pressure measurement system: A preliminary study

The Foot ◽  
2012 ◽  
Vol 22 (1) ◽  
pp. 35-39 ◽  
Author(s):  
Aoife Healy ◽  
Philip Burgess-Walker ◽  
Roozbeh Naemi ◽  
Nachiappan Chockalingam
Keyword(s):  
Measurement System ◽  
Pressure Measurement ◽  
System A ◽  
Preliminary Study ◽  
Pressure Measurement System
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