AE Characterization of Brick Masonry Walls Mechanical Behavior: The Case-Study of Alessandria and Boves Barracks

2019 ◽  
Vol 817 ◽  
pp. 563-570 ◽  
Author(s):  
Nicola Viale ◽  
Federico Accornero ◽  
Giuseppe Lacidogna ◽  
Giulio Ventura
Keyword(s):  
Scale Effects ◽  
Brick Masonry ◽  
Test Method ◽  
Critical Conditions ◽  
Masonry Walls ◽  
Significant Information ◽  
Strain Relationship ◽  
The Difference ◽  
Extent Of Damage ◽  
Relationship Of

IIn the present study, Acoustic Emission (AE) monitoring technique is applied in order to characterize the brick masonry of two important military buildings located in Northern Italy: the barracks of Alessandria and Boves. The internal brick masonry walls of the two barracks object of the study are tested by two double flat-jack systems, in order to analyze the compressive strength of the structural material. Flat-jack testing is a versatile and powerful technique that provides significant information on the mechanical properties of historical constructions. The first applications of this technique on some historical monuments clearly showed its great potential. The flat-jack test method is only slightly destructive, and when double jacks are used, this test works according to the same principle as a standard compressive test. The difference is that it is performed in situ and the load is applied by means of two flat-jacks instead of the loading platens. During the tests, the stress-strain relationship of the masonry is determined by gradually increasing the pressure applied by the flat-jacks in the course of three loading-unloading cycles. Moreover, AE technique is coupled to the flat-jack testing, in order to assess the extent of damage in the masonry texture. Thus, AE technique makes it possible to highlight critical phenomena and fracture mechanics scale effects in the masonry by identifying the critical conditions, not entrusted to an analysis of the loading process (compression or shear), rather depending primarily on the distribution and evolution of crack patterns.

scholarly journals Experimental Study on the Compressive Behaviors of Brick Masonry Strengthened with Modified Oyster Shell Ash Mortar

Buildings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 266
Author(s):  
Zhouyi Chen ◽  
Wenyuan Chen ◽  
Chenglin Mai ◽  
Jianguang Shi ◽  
Yiren Xie ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Poor Performance ◽  
Oyster Shell ◽  
Brick Masonry ◽  
Masonry Walls ◽  
Test Results ◽  
Strain Relationship ◽  
Design Requirements ◽  
Relationship Of ◽  
Strengthening Method

Masonry bricks were widely used in construction of the walls in most of Chinese historical buildings. The low strength of lime–clay mortar used in existing historical brick masonry walls has usually led to poor performance such as cracking and collapse during earthquakes. As the composition of modified oyster shell ash mortar (MOSA mortar) with higher strength is similar to that of lime–clay mortar, it can be used to partially replace original lime–clay mortar for historical brick masonry buildings in order to improve their seismic performance. Previous research has proven that this strengthening method for brick masonry is effective in improving shear strength. In this paper, we present further experimental research regarding the compressive behaviors of brick masonry strengthened by replacing mortar with a MOSA mortar. The test results showed that the compressive strength of brick masonry specimens strengthened by the proposed method meets the design requirements. The formula for calculating compressive strength for brick masonry strengthened by replacing mortar was obtained by fitting the test results. The calculated values were consistent with the tested ones. In addition, the stress–strain relationship of tested specimens under axial compression was simulated using the parabolic model.

Location Of Residual Donors In GaN Epitaxial Layers

1997 ◽  
Vol 482 ◽  
Author(s):  
E. R. Glaser ◽  
T. A. Kennedy ◽  
A. E. Wickenden ◽  
D. D. Koleske ◽  
W. G. Perry ◽  
...  
Keyword(s):  
Double Resonance ◽  
High Resistivity ◽  
Biaxial Compression ◽  
Electron Nuclear Double Resonance ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Strain Relationship ◽  
The Difference ◽  
Optically Detected ◽  
Relationship Of

AbstractOptically-detected electron-nuclear double resonance (ODENDOR) studies at 24 GHz on high-resistivity GaN films grown on Al2O3 have been combined with x-ray diffraction measurements to obtain information on the location of the residual shallow donors. Strong ODENDOR assigned to 69,71Ga lattice nuclei was detected on the g=1.951 effective-mass donor resonance found on the 2.2 eV emission bands. The x-ray studies reveal that the layers are under biaxial compression with high values of strain (∼ 2–3 × 10−3). The quadrupole splittings for 69Ga are smaller than those reported for strain-free samples by 15–25 %. The dominant sources of the local electric field gradient (EFG) responsible for the splittings are attributed to the wurtzite crystal structure and the strain fields that arise from the lattice constant mismatch and the difference in thermal expansion coefficients. An EFG/strain relationship of 3 × 1022 Vm−2 per unit strain at the 69,71Ga nuclei is deduced. The ODENDOR can be described with asymmetry parameter η=0. This provides evidence that the donors are in the crystallites rather than near grain boundaries.

Study on the Difference between Multipotiential Surface Model and Duncan-Chang Model Based on the Triaxial Test of Heda Highway Turfy Soil

2012 ◽  
Vol 538-541 ◽  
pp. 965-970 ◽  
Author(s):  
Shuai Tang ◽  
Lei Nie ◽  
Dao Yong Qiao ◽  
Yan Lv ◽  
Xu Ran Yang
Keyword(s):  
Triaxial Test ◽  
Axial Strain ◽  
Surface Model ◽  
Model Based ◽  
Strain Relationship ◽  
The Difference ◽  
Relationship Of ◽  
The Relationship ◽  
Chang Model

Firstly, this paper determined the experiment parameter of Duncan-Chang model, through Heda highway turfy soil ordinary triaxial test. Then get to the elastics strain relationship of the multipotiential surface model according to the data above. And finally get the applicable category of the two model through the contrast of the relationship of body strain and axial strain and the relationship of partial stress and axial strain.

Systolic quick releases of nonexcised blood-perfused canine papillary muscle

1980 ◽  
Vol 238 (2) ◽  
pp. H153-H155
Author(s):  
H. Suga
Keyword(s):  
Papillary Muscle ◽  
Papillary Muscles ◽  
Quick Release ◽  
Stiffness Constant ◽  
Length Relationship ◽  
Strain Change ◽  
Strain Relationship ◽  
The Mean ◽  
The Difference ◽  
Relationship Of

Systolic stiffness was studied in five coronary perfused twitching papillary muscles of canine right ventricles. The muscles beat at regular sinus rhythms at 37 degrees C. They were shortened quickly at about 10 muscle lengths/s in the middle of isometric contractions. Systolic force decreased exponentially with the shortening in the force-length diagram. Relating Lagrangian stress (sigma) and strain change (delta epsilon) relative to isometric length calculated from the force-length relationship curve during quick release, I found a linear relationship between ln sigma and delta epsilon. This indicates that the systolic stres-strain relationship of the canine papillary muscle can be approximated by an exponential curve, sigma = sigma m exp(k . delta epsilon), where sigma m = isometric stress at the onset of quick release. The mean +/- SE of the stiffness constant k was calculated to be 55 +/- 8 (dimensionless). These k values are greater than those of excised cat papillary muscles at 37 degrees C reported in literature. This difference in k values may be ascribed to the difference in the mechanical property of the uncut pinned end of the present preparation as opposed to the cut clamped end of the conventional preparation, although the canine and feline papillary muscles may simply have the different k values.

Lungs Under Cyclic Compression and Expansion

1987 ◽  
Vol 109 (2) ◽  
pp. 160-162 ◽  
Author(s):  
Z. L. Tao ◽  
Y. C. Fung
Keyword(s):  
Strain History ◽  
Rabbit Lung ◽  
Compression Waves ◽  
Cyclic Compression ◽  
Volume Relationship ◽  
Compression And Expansion ◽  
Strain Relationship ◽  
Pressure Volume Relationship ◽  
The Difference ◽  
Relationship Of

The pressure-volume relationship of lungs subjected to repeated compression and expansion is studied in detail. The investigation was motivated by an attempt to understand why lungs are frequently injured by compression waves; hence the lung was compressed to a degree greater than normally encountered in physiological conditions. Attention was focused on the collapse of the lung at a critical strain and the reopening of the trap at a critical stress. We found that when a rabbit lung is compressed, about one-half to one-quarter of its gas may be trapped in the alveoli because of the closure of airways. Reopening of the trap occurs at a pressure higher than the critical pressure for collapsing. The difference of the critical pressures of collapsing and reopening is influenced by the rate of strain and the strain history, especially by the maximum compressive stress imposed on the lung. The stress-strain relationship of the lung tissue, which resembles the PV curves, depends strongly on the strain history.

An evaluation of ECT sample height for small flute board grades and Box Manufacturer’s Certification compliance

TAPPI Journal ◽  
2009 ◽  
Vol 8 (6) ◽  
pp. 24-28
Author(s):  
CORY JAY WILSON ◽  
BENJAMIN FRANK
Keyword(s):  
Compressive Strength ◽  
Compressive Load ◽  
Test Sample ◽  
Test Methods ◽  
Test Method ◽  
Initial Development ◽  
Sample Height ◽  
Relationship Of ◽  
The Relationship ◽  
Corrugated Fiberboard

TAPPI test T811 is the specified method to ascertain ECT relative to box manufacturer’s certification compliance of corrugated fiberboard under Rule 41/ Alternate Item 222. T811 test sample heights were derived from typical board constructions at the time of the test method’s initial development. New, smaller flute sizes have since been developed, and the use of lighter weight boards has become more common. The T811 test method includes sample specifications for typical A-flute, B-flute, and C-flute singlewall (and doublewall and triplewall) structures, but not for newer thinner E-flute or F-flute structures. This research explores the relationship of ECT sample height to measured compressive load, in an effort to determine valid E-flute and F-flute ECT sample heights for use with the T811 method. Through this process, it identifies challenges present in our use of current ECT test methods as a measure of intrinsic compressive strength for smaller flute structures. The data does not support the use of TAPPI T 811 for ECT measurement for E and F flute structures, and demonstrates inconsistencies with current height specifi-cations for some lightweight B flute.

Tire Treadwear — A Comprehensive Evaluation of the Factors: Generic Type, Aspect Ratio, Tread Pattern, and Tread Composition Part I: Introduction and Details on the Organization of the Program

1986 ◽  
Vol 14 (4) ◽  
pp. 201-218 ◽  
Author(s):  
A. G. Veith
Keyword(s):  
Aspect Ratio ◽  
Comprehensive Evaluation ◽  
Test Method ◽  
Interactive Effects ◽  
Data Analyses ◽  
Main Effect ◽  
Systematic Determination ◽  
Relationship Of ◽  
The Relationship

Abstract This four-part series of papers addresses the problem of systematic determination of the influence of several tire factors on tire treadwear. Both the main effect of each factor and some of their interactive effects are included. The program was also structured to evaluate the influence of some external-to-tire conditions on the relationship of tire factors to treadwear. Part I describes the experimental design used to evaluate the effects on treadwear of generic tire type, aspect ratio, tread pattern (groove or void level), type of pattern (straight rib or block), and tread compound. Construction procedures and precautions used to obtain a valid and functional test method are included. Two guiding principles to be used in the data analyses of Parts II and III are discussed. These are the fractional groove and void concept, to characterize tread pattern geometry, and a demonstration of the equivalence of wear rate for identical compounds on whole tread or multi-section tread tires.

It Keeps Me Seeking

2018 ◽  
Author(s):  
Andrew Briggs ◽  
Hans Halvorson ◽  
Andrew Steane
Keyword(s):  
Evolutionary Biology ◽  
Quantum Physics ◽  
Natural World ◽  
Theological Reflection ◽  
Fine Tuning ◽  
Good Argument ◽  
The Difference ◽  
Argument From Design ◽  
Relationship Of

Two scientists and a philosopher aim to show how science both enriches and is enriched by Christian faith. The text is written around four themes: 1. God is a being to be known, not a hypothesis to be tested; 2. We set a high bar on what constitutes good argument; 3. Uncertainty is OK; 4. We are allowed to open up the window that the natural world offers us. This is not a work of apologetics. Rather, the text takes an overview of various themes and gives reactions and responses, intended to place science correctly as a valued component of the life of faith. The difference between philosophical analysis and theological reflection is expounded. Questions of human identity are addressed from philosophy, computer science, quantum physics, evolutionary biology and theological reflection. Contemporary physics reveals the subtle and open nature of physical existence, and offers lessons in how to learn and how to live with incomplete knowledge. The nature and role of miracles is considered. The ‘argument from design’ is critiqued, especially arguments from fine-tuning. Logical derivation from impersonal facts is not an appropriate route to a relationship of mutual trust. Mainstream evolutionary biology is assessed to be a valuable component of our understanding, but no exploratory process can itself fully account for the nature of what is discovered. To engage deeply in science is to seek truth and to seek a better future; it is also an activity of appreciation, as one may appreciate a work of art.

Dynamic network intelligent hybrid recommendation algorithm and its application in online shopping platform

2021 ◽  
pp. 1-13
Author(s):  
Yuxuan Gao ◽  
Haiming Liang ◽  
Bingzhen Sun
Keyword(s):  
Online Shopping ◽  
Rapid Development ◽  
Dynamic Network ◽  
Topsis Method ◽  
Recommendation Algorithm ◽  
Time Periods ◽  
The Difference ◽  
Relationship Of ◽  
Hybrid Recommendation ◽  
Novel Model

With the rapid development of e-commerce, whether network intelligent recommendation can attract customers has become a measure of customer retention on online shopping platforms. In the literature about network intelligent recommendation, there are few studies that consider the difference preference of customers in different time periods. This paper proposes the dynamic network intelligent hybrid recommendation algorithm distinguishing time periods (DIHR), it is a integrated novel model combined with the DEMATEL and TOPSIS method to solved the problem of network intelligent recommendation considering time periods. The proposed method makes use of the DEMATEL method for evaluating the preference relationship of customers for indexes of merchandises, and adopt the TOPSIS method combined with intuitionistic fuzzy number (IFN) for assessing and ranking the merchandises according to the indexes. We specifically introduce the calculation steps of the proposed method, and then calculate its application in the online shopping platform.

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