scholarly journals Improvement of Accuracy of Control of Physical‑Mechanical Characteristics of Materials By Ultrasonic Pulse Method Due to Reduction of Measurement Error of Propagation Time of Elastic Waves

2018 ◽  
pp. 31-35
Author(s):  
Ya. Serikov
Keyword(s):  
Mechanical Characteristics ◽  
Pulse Method ◽  
Structural Heterogeneity ◽  
Ultrasonic Pulse ◽  
Ultrasonic Signal ◽  
Ultrasonic Transducers ◽  
Propagation Time ◽  
Information Signal ◽  
Pass Through ◽  
Definition Of

Ensuring the reliability of buildings, structures, analysis of their structural elements during reconstruction or major repair includes the task of determining the physical and mechanical characteristics of materials — strength, homogeneity, evaluation of structural heterogeneity, the presence of microcracks, etc. In solving this problem, an ultrasonic pulse method of non-destructive quality control is used. The basis of the method is the dependence of the parameters of ultrasonic oscillations, on these characteristics when they pass through the material. As the main parameter of the information ultrasonic signal, the time of its passage from the radiating to the receiving ultrasonic transducers is used. The amplitude of the information ultrasonic signal to a large extent depends on the structure of the investigated material, its acoustic resistance. At significant violations of the structure of the material there is a significant decrease in the amplitude of the information signal, which causes an increase in the error of measuring the time of its passage, and hence the definition of characteristics, quality of the investigated material. The article describes the developed method of increasing the accuracy of measuring the time of passage of the ultrasonic signal from the radiating to the receiving ultrasonic transducers. The essence of the technique is to use the mathematical modeling of the shape of the ultrasound signal, in particular the form of its so-called «first introduction».

scholarly journals Problems of Development and Implementation of Ultrasonic Pulse Method in the Problem of Measurement of Parameters for Determination of Physical-Mechanical Characteristics of Concrete Maintained Buildings and Constructions

2019 ◽  
pp. 56-61
Author(s):  
Ya. Serikov
Keyword(s):  
Construction Projects ◽  
System Analysis ◽  
Mechanical Characteristics ◽  
Pulse Method ◽  
Ultrasonic Pulse ◽  
Destructive Testing ◽  
Stage Of Development ◽  
Foreign Countries ◽  
Ultrasonic Devices ◽  
Physical And Mechanical Characteristics

The current stage of development of the construction industry of Ukraine and foreign countries contains the direction to extend the life of the operated construction projects. This direction is directly related to the research of physical and mechanical characteristics of concrete as the main building material. A significant number of such studies can be performed using the ultrasonic pulse method. But despite its potential practice shows the insufficient level of use of this method. Thus, this method, in addition to determining the strength of concrete, allows to determine its characteristics such as the level of crack formation, geometric parameters of the planes of stratification in monolithic concrete, and the like. The system analysis of technical characteristics of serial ultrasonic devices that are produced in Ukraine and foreign countries is carried out. The results of the analysis revealed that their technical characteristics allow measurements, mainly to determine the strength, uniformity of concrete. These devices also do not allow to measure vibration, noise and electrical interference, which is typical for production conditions. The conducted researches allowed to reveal the main directions of improvement of serial ultrasonic devices, Metrology. This allows us to solve the problem of expanding the application of this method in the practice of non-destructive testing of physical and mechanical characteristics of concrete operated construction projects.

scholarly journals EVALUACIÓN DE LOS RIESGOS DE AFECTACIÓN POR EL ESTABLECIMIENTO DE GRANJAS ATUNERAS EN RELACIÓN CON LA DISTRIBUCIÓN ESPACIAL DE CETÁCEOS EN EL GOLFO DULCE, COSTA RICA

2011 ◽  
Vol 1 ◽  
pp. 159 ◽  
Author(s):  
Lenin E. Oviedo Correa ◽  
Juan Diego Pacheco ◽  
David Herra Miranda
Keyword(s):  
Fish Fauna ◽  
Humpback Whales ◽  
Marine Biodiversity ◽  
Limiting Factor ◽  
Predator Population ◽  
Incidental Capture ◽  
Top Predators ◽  
Habitat Niche ◽  
Pass Through ◽  
Definition Of

Este estudio trata sobre la distribución espacial de depredadores marinos topes, particularmente cetáceos odontocetos y misticetos migratorios. Se describe el riesgo potencial de afectación por el establecimiento de instalaciones asociadas con operaciones locales de maricultura: jaulas de engorde para atún. Por medio de un enfoque teórico y empírico se establece cuantitativamente como la profundidad máxima, un factor limitante en la distribución y definición del nicho ecológico de cetáceos, se solaparía en valores con el área propuesta para el establecimiento de las jaulas, lo que induciría dos escenarios probables de afectación: el desplazamiento de las poblaciones de depredadores de un hábitat-nicho de alimentación potencial y la interacción progresiva entre los depredadores con la fauna acompañante alrededor de las instalaciones de la operación de cultivo, lo anterior implicaría un riesgo perenne de captura incidental de dichos depredadores. Adicionalmente, la presencia de ballenas jorobadas durante la temporada de lluvia en zonas aledañas a Punta Banco, se asociaría a una ruta migratoria desde las zonas de alimentación en Sudamérica-Antártica, que pasaría por el área proyectada para el establecimiento de la operación de maricultura. Los resultados ilustran la necesidad de seguir un principio precautorio y promover la reubicación de proyecto de maricultura en áreas de menor valor en términos de biodiversidad marina.This contribution deals with the spatial distribution of marine top predators, particularly odontocete and migratory misticete cetaceans. The study describes the potential risk of disturbances due to the establishment of mariculture operations and corresponding infrastructure: tuna feed lots. Through a mixed theoretical and empirical approach, this research corroborates how the maximum depth, a limiting factor in the definition of cetacean trophic niches off the study area, overlaps with the values for depths from an area proposed as the focal location of a tuna feed lot facility. The latter implies two particular scenarios: the translocation of the local predator population from a potential foraging habitat-niche, and the progressive negative interaction between predators and the accompanying fish fauna around of the cages, with a high probability of incidental capture of those predators by entanglement. Additionally, the occurrence of humpback whales during the rainy season associated with a migratory route from feeding grounds off Chile-Antarctica, that would pass through the area projected to harbor the mariculture operation. The results illustrate the need of considering a precautionary approach and relocate mariculture projects to areas of lesser value in terms of marine biodiversity.

scholarly journals 2D IPO's for Constant Speed Lines, Curves, NURBS

2019 ◽  
Author(s):  
Valere Huypens
Keyword(s):  
Major Axis ◽  
Pulse Method ◽  
Constant Speed ◽  
Sampled Data ◽  
Reference Pulse ◽  
Production Manager ◽  
Definition Of ◽  
The Right ◽  
2D And 3D ◽  
Better Than

<div>Current constant speed IPO's, usually, use Sampled-data IPO's and constant speed lines use the </div><div>wrong initialized software DDA-ipo's, which make these IPO's unusable. The Bresenham- and </div><div>midpoint IPO's are non-constant speed reference pulse IPO's with bounded inaccuracy.</div><div>By adding an ultra-fast 3-lines algorithm "PRM-cs" to the actual midpoint or Bresenham algorithms, </div><div>we convert these midpoint-ipo's to very fast, constant speed, reference pulse IPO's. </div><div>This applies to 2D-lines, 3D-lines, 2D-curves and 2D-NURBS.</div><div>The PRM-cs measures, in real-time, the length of the discrete curve and the PRM-cs is completely new. </div><div>We define the best IPO, the major axis principle and the LSD-priority. </div><div>The major axis principle holds for the actual 3D-line IPO's. These IPO's are, generally, inaccurate, </div><div>but they can be updated to constant speed 3D-line IPO's, when the production manager agrees.</div><div>The Digital Geometric Geometry (DAG) defines the discrete lines globally, but this global </div><div>definition of a discrete 3D-line, gives discrete 3D-lines whose accuracy is much less than the </div><div>accuracy of the best discrete 3D-lines (e.g. 37% worse).</div><div>We describe the three causes of the inaccurate (imperfect) discrete 3D-lines. </div><div>All existing pulse-rate or PRM-ipo's use a wrong initialization, which deteriorates the accuracy. </div><div>We determine the right initialization for the new PRM-cs and the updated PRM-ipo. </div><div>We propose the benchmark-ipo "listSIM-ipo". This constant speed IPO can, also, be used in real-</div><div>time for every 2D- and 3D-curve. </div><div>The 3rd-degree Trident NURB shows that the constant speed reference pulse method is much </div><div>better than the existing sampled-data methods.</div>

Non-Destructive Tests as Durability Indicators in Cement Mortars with Pozzolanic Substitutions

2017 ◽  
Vol 902 ◽  
pp. 9-13
Author(s):  
Rosalía Ruiz Ruiz ◽  
Elia Mercedes Alonso Guzmán ◽  
Wilfrido Martínez Molina ◽  
Hugo Luis Chávez García ◽  
Judith Alejandra Velázquez Perez
Keyword(s):  
Mechanical Characteristics ◽  
Ultrasonic Pulse Velocity ◽  
Good Alternative ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Cement Industry ◽  
Capillary Absorption ◽  
Pozzolanic Material ◽  
Cement Mortars ◽  
Non Destructive

Cement industry is responsible of 5-7% of CO2 emissions to the atmosphere. This is preoccupant because this is one of the greenhouse effect gases which cause global warming. Pozzolanic material incorporation in cement mortars elaboration represents a good alternative to partially substitute cement, since its chemical composition could contribute to improvement of its durability and mechanical characteristics. In this research, mortars with pozzolanic substitutions are evaluated through non-destructive tests as: capillary absorption, electrical resistivity, and ultrasonic pulse velocity to the age of 1000 days. The results suggested that the incorporation of pozzolanic material as partial substitutes of Portland cement increases the mortars properties mainly in substitutions of CBC 20%, PN 10, and 30%.

ENTRE "MOTS MUETS" ET SILENCE BRUISSANT: le 'je' en tension

2008 ◽  
Vol 19 (1) ◽  
pp. 383-391
Author(s):  
Julia Siboni
Keyword(s):  
Pass Through ◽  
Definition Of

Throughout his oeuvre, Beckett wavers between "unspoken words" and murmurous silences questioning in this manner the nature of the existence of "true silence." The tension between these two poles reflects the perpetual (re)construction, (re)definition of an inside and outside, interiority and exteriority. Indeed, the limit between these two spaces turns out to be more often than not mobile and porous, letting sound pass through. Thus the Beckettian subject is called on to search for a place in this profoundly dynamic space of tension, which is both limit and border and the ground of a precarious and elusive identity.

scholarly journals SPILLING BREAKERS, BORES, AND HYDRAULIC JUMPS

1978 ◽  
Vol 1 (16) ◽  
pp. 30 ◽  
Author(s):  
D.H. Peregrine ◽  
I.A. Svendsen
Keyword(s):  
Water Waves ◽  
Mean Flow ◽  
The Mean ◽  
White Water ◽  
Pass Through ◽  
Definition Of ◽  
Spilling Breakers ◽  
Almost All ◽  
Plunging Breaker ◽  
Spilling Breaker

On gently sloping beaches, almost all water waves break. After the initial breaking the water motion usually appears quite chaotic. However, for a moderate time, for example two or three times the descent time of the "plunge" in a plunging breaker, the flow can be relatively well organised despite the superficial view which is largely of spray and bubbles. If waves continue to break the breaking motion, or "white water" soon becomes fully turbulent and the mean motions become quasisteady. A reasonable definition of a quasi-steady wave is one which changes little during the time a water particle takes to pass through it. We exclude water particles which may become trapped in a surface roller and surf along with the wave. At this stage in its development a wave on a beach may be described as a spilling breaker or as a bore. In fact, there is a range of these waves from those with a little white water at the crest to examples where the whole front of the wave is fully turbulent. In investigating the properties of such waves it is desirable to start by looking at the whole range of related motions. The most obvious extension is to the hydraulic jump; since, in the simplest view, it is equivalent to a bore but in a frame of reference moving with the wave. It is also an example where the mean flow is steady rather than quasisteady.

Relationship Between Some Physico-Mechanical Properties and Numerical Indexes of Graphite Shape in Compacted-Vermicular Graphite Cast Irons

1982 ◽  
Vol 104 (1) ◽  
pp. 60-65
Author(s):  
Yuichi Tanaka ◽  
Hakaru Saito ◽  
Ikuo Tokura ◽  
Katsuya Ikawa
Keyword(s):  
Mechanical Properties ◽  
Cast Iron ◽  
Mechanical Characteristics ◽  
Point Of View ◽  
Cast Irons ◽  
Graphite Cast Iron ◽  
Mechanical And Physical Properties ◽  
Definition Of ◽  
Thermal Diffusivities ◽  
The Relationship

The main purpose of this paper is to present some data on the mechanical and physical properties of compacted-vermicular graphite cast iron and to give a reasonable interpretation to the characteristics by using numerical indexes indicating the shape of graphite flakes in the structure. After describing the preparation of the material and a new method for measuring thermal diffusivity of the iron, the influence of kind and amount of alloy added for treatment and of cooling rate upon the graphite shape is discussed by using the indexes of the structure. The thermal diffusivities and mechanical characteristics such as tensile strength and hardness are shown as functions of the indexes to clarify the relationship between them. Furthermore, the present indexes are compared with those proposed earlier to find which is most suitable for the cast iron treated in this work. Authors propose a definition of compacted-vermicular graphite cast iron, which is reasonable from the physico-mechanical point of view, and also show some typical mechanical properties and measures required to produce such cast iron with desirable features.

To the Problems of Determination of Dynamic Elasticity Modules of Calcium Silicate Bricks by Means of Resonance Method

2014 ◽  
Vol 897 ◽  
pp. 139-143 ◽  
Author(s):  
Jiří Brožovský ◽  
Ámos Dufka
Keyword(s):  
Modulus Of Elasticity ◽  
Calcium Silicate ◽  
Building Materials ◽  
Resonance Method ◽  
Pulse Method ◽  
Ultrasonic Pulse ◽  
Test Methods ◽  
Test Method ◽  
Resonance Test ◽  
Accuracy Of Measurement

Modulus of elasticity of building materials can be determined in a static way (loading in a press) or by means of non-destructive test methods (ultrasonic pulse method and resonance method); the parameter is most frequently determined for concrete and both methods of determining elasticity modulus are codified in Standards. Elasticity characteristics of calcium silicate bricks were determined by means of resonance test method. Because the shape of calcium silicate bricks (a block with oblong foot) is different from the shape of test specimens for concrete (usually blocks with square foot), expected frequencies for verification of accuracy of measurement by resonance method were determined. Moisture content of calcium silicate bricks (water absorbing capacity is up to 12-14%) has influence on the value of resonance frequency. Difference between dynamic Young's modulus of elasticity from fundamental longitudinal and transverse resonant frequency is on average 2.8%.

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