THE RESULTS OF EXPERIMENTAL STUDIES OF THE PROCESS OF REDISTRIBUTION OF SELF-OSCILLATION ENERGY UNDER THE INFLUENCE OF ATTENUATES

2019 ◽  
pp. 46-51 ◽  
Author(s):  
A. M. Konovalov ◽  
V. I. Kugushev ◽  
A. Yu. Yakovlev
Keyword(s):  
Nondestructive Testing ◽  
Small Amplitude ◽  
Rectangular Cross Section ◽  
Experimental Studies ◽  
Energy Redistribution ◽  
Damping Effect ◽  
Highly Sensitive ◽  
Oscillation Energy ◽  
Split Mode ◽  
The Given

Below given are the results of experimental studies of the process of damping of self-oscillation of the beam which is a long plate with rectangular cross-section. The studies were aimed at demonstration of the process (accompanying the damping) of energy redistribution between the modes and harmonics of self-oscillations under the conditions when this energy is essentially bounded. The artificial damper was used which was a small-size slightly pressed plate. The same local damping effect is created by cracks in the parts when there are oscillations, plastic deformation at the apex of crack. Specially developed transducers operating in split mode as part of multifunction acoustic impedance fault detector were used as measuring equipment. The receiver-transducer was attached at the end of the beam, the generator-transducer was attached at the centre of the beam so as to induce oscillation train consisting of five dominant flexural modes of self-oscillations of the beam. Limitation of energy inducing self-oscillations was determined by the rigidity of spring-plates of generator-transducer. The rigidity of the plates was chosen so as oscillation energy was sufficient only for extraction of the given train amplitudes as being dominant, whereas the rest modes of self-oscillations were either not induced at all or were induced with small amplitude. It is demonstrated that redistribution process, when inducing energy is limited, is highly sensitive to attenuants, which allows to use it as a crack indicator during integral nondestructive testing of parts and entire assemblies. For this reason it is concluded that the process of energy redistribution between different harmonics and modes of self-oscillations under the influence of damping factors is advanced for computer-aided nondestructive testing.

scholarly journals Isospectrals of non-uniform Rayleigh beams with respect to their uniform counterparts

2018 ◽  
Vol 5 (2) ◽  
pp. 171717 ◽  
Author(s):  
Srivatsa Bhat K ◽  
Ranjan Ganguli
Keyword(s):  
Boundary Condition ◽  
Cross Section ◽  
Natural Frequencies ◽  
Rectangular Cross Section ◽  
Beam Equation ◽  
The Finite Element Method ◽  
Rayleigh Beam ◽  
Uniform Beam ◽  
Governing Differential Equation ◽  
The Given

In this paper, we look for non-uniform Rayleigh beams isospectral to a given uniform Rayleigh beam. Isospectral systems are those that have the same spectral properties, i.e. the same free vibration natural frequencies for a given boundary condition. A transformation is proposed that converts the fourth-order governing differential equation of non-uniform Rayleigh beam into a uniform Rayleigh beam. If the coefficients of the transformed equation match with those of the uniform beam equation, then the non-uniform beam is isospectral to the given uniform beam. The boundary-condition configuration should be preserved under this transformation. We present the constraints under which the boundary configurations will remain unchanged. Frequency equivalence of the non-uniform beams and the uniform beam is confirmed by the finite-element method. For the considered cases, examples of beams having a rectangular cross section are presented to show the application of our analysis.

Moderate Reynolds Number Mixing in a T-Channel

2010 ◽  
Author(s):  
Susan Thomas ◽  
Tim Ameel
Keyword(s):  
Reynolds Number ◽  
Cross Section ◽  
Rectangular Cross Section ◽  
Large Body ◽  
Experimental Studies ◽  
Numerical Work ◽  
Moderate Reynolds Number ◽  
Wide Range ◽  
Particle Imaging ◽  
Experimental Trials

An experimental investigation of water flow in a T-shaped channel with rectangular cross section (20 × 20 mm inlet ID and 20 × 40 mm outlet ID) has been conducted for a Reynolds number Re range of 56 to 422, based on inlet diameter. Dynamical conditions and the T-channel geometry of the current study are applicable to the microscale. This study supports a large body of numerical work, and resolution and the interrogation region are extended beyond previous experimental studies. Laser induced fluorescence (LIF) and particle imaging velocimetry (PIV) are used to characterize flow behaviors over the broad range of Re where realistic T-channels operate. Scalar structures previously unresolved in the literature are presented. Special attention is paid to the unsteady flow regimes that develop at moderate Re, which significantly impact mixing but are not yet well characterized or understood. An unsteady symmetric topology, which develops at higher Re and negatively impacts mixing, is presented, and mechanisms behind the wide range of mixing qualities predicted for this regime are explained. An optimal Re operating range is identified based on multiple experimental trials.

Diffusion Combustion Of The Round Microjet Mixture Of Hydrogen With Metane, Helium And Nitrogen

2016 ◽  
Vol 11 (2) ◽  
pp. 56-76
Author(s):  
Andrey Shmakov ◽  
Genrich Grek ◽  
Viktor Kozlov ◽  
Yuriy Litvinenko ◽  
Oleg Korobeinichev
Keyword(s):  
Turbulent Flame ◽  
Combustion Process ◽  
Experimental Studies ◽  
Diffusion Combustion ◽  
Pure Hydrogen ◽  
Hydrogen Mixture ◽  
Combustion Features ◽  
The Given ◽  
Stabilization Of Combustion

The purpose of the given work will consist in an experimental studies of the diffusion combustion features of the hydrogen round microjet mixtures with the metane, helium and nitrogen. It is found, that the mechanism and characteristics of a microjet and a flame evolution at diffusion combustion of the hydrogen mixture with the metane, helium or nitrogen are connected with the «bottleneck» flame area formation, as well as in a situation of a pure hydrogen microjet diffusion combustion. It is revealed, that process of diffusion combustion of a hydrogen / metane mixture in a round microjet is accompanied by stage-by-stage stages of a turbulent flame detachment at preservation of combustion in the «bottleneck» flame area, and, at last extinction of microjet combustion that correlates with combustion process of a similar microjet of pure hydrogen. It is found, that all above-listed stages of a hydrogen / metane mixture combustion are realized in a range considerably smaller speeds of a microjet (200÷500 m/sec), than in a similar situation of a pure hydrogen microjet combustion (600÷800 m/sec). It is shown, that at diffusion combustion of a mixture of hydrogen with metane or helium or nitrogen in a round microjet for stabilization of combustion with growth of a microjet speed it is necessary to increase a portion of hydrogen (or to reduce a portion of an impurity) in a mixture of gases.

Development and Validation of UV Spectroscopy Method for the Estimation of Dolutegravir in Bulk and Pharmaceutical Dosage Form

2021 ◽  
pp. 188-190
Author(s):  
Vaishnavi Dulange ◽  
G.B. Gajeli
Keyword(s):  
Dosage Form ◽  
Uv Spectroscopy ◽  
Spectroscopic Method ◽  
Water Mixture ◽  
Uv Spectrum ◽  
Pharmaceutical Dosage Form ◽  
Highly Sensitive ◽  
Development And Validation ◽  
The Given ◽  
Regression Correlation

UV spectroscopic method was developed for the estimation of Dolutegravir in bulk and Formulation.The UV spectrum of Dolutegravir in methanol and water mixture showed λ max at 254nm. Beer’s law is valid in the concentration range of 10-50µg/ml. This method was validated for linearity, accuracy, precision, LOD and LOQ. The method has demonstrated excellent linearity over the range of 10-50µg/ml with regression equation y = 0.030x + 0.008 and regression correlation coefficient r2= 0.998. Moreover, the method was found to be highly sensitive with LOD (2.056μg/ml) and LOQ (6.230μg/ml). Depending on results the given method can be successfully applied for assay of Dolutegravir in formulation.

Pneumatic and similar breakwaters

1955 ◽  
Vol 231 (1187) ◽  
pp. 457-466 ◽  
Keyword(s):  
Small Amplitude ◽  
Wave Motion ◽  
Surface Current ◽  
Water Velocity ◽  
Air Injection ◽  
Air Bubbles ◽  
Surface Currents ◽  
Damping Effect ◽  
Water Jets ◽  
Set Up

The process of calming waves by injecting air bubbles beneath the surface has been known to civil engineers for nearly 50 years. It has been little used for its results have been erratic, its method of working was unknown and its effect could not be predicted. The investigation described in this paper has shown that the surface currents set up by air injection, and the distribution of the water velocity within the currents, can be matched by currents set up by water jets, and that the two currents so matched have almost the same wave-damping effect whether they are set up by water jets or by air. It is concluded that the bubbles as such have at most a very small effect on the wave motion. It is found that waves of small amplitude are stopped in the way predicted theoretically, but that as the amplitude increases the surface current necessary to stop waves of a given length increases.

scholarly journals Estrogen Receptor β-Mediated Inhibition of Male Germ Cell Line Development in Mice by Endogenous Estrogens during Perinatal Life

Endocrinology ◽  
2004 ◽  
Vol 145 (7) ◽  
pp. 3395-3403 ◽  
Author(s):  
Géraldine Delbès ◽  
Christine Levacher ◽  
Catherine Pairault ◽  
Chrystèle Racine ◽  
Clotilde Duquenne ◽  
...  
Keyword(s):  
Estrogen Receptor ◽  
Germ Cell ◽  
Experimental Studies ◽  
Cell Lineage ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Testicular Development ◽  
Fetal Life ◽  
Germ Cell Line ◽  
Highly Sensitive ◽  
Labeling Method

Abstract Epidemiological, clinical, and experimental studies have suggested that excessive exposure to estrogens during fetal/neonatal life can lead to reproductive disorders and sperm abnormalities in adulthood. However, it is unknown whether endogenous concentrations of estrogens affect the establishment of the male fetal germ cell lineage. We addressed this question by studying the testicular development of mice in which the estrogen receptor (ER) β or the ERα gene was inactivated. The homozygous inactivation of ERβ (ERβ−/−) increased the number of gonocytes by 50% in 2- and 6-d-old neonates. The numbers of Sertoli and Leydig cells and the level of testicular testosterone production were unaffected, suggesting that estrogens act directly on the gonocytes. The increase in the number of gonocytes did not occur during fetal life but instead occurred just after birth, when gonocytes resumed mitosis and apoptosis. It seems to result from a decrease in the apoptosis rate evaluated by the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling method and cleaved caspase-3 immunohistochemical detection. Last, mice heterozygous for the ERβ gene inactivation behaved similarly to their ERβ−/− littermates in terms of the number of gonocytes, apoptosis, and mitosis, suggesting that these cells are highly sensitive to the binding of estrogens to ERβ. ERα inactivation had no effect on the number of neonatal gonocytes and Sertoli cells. In conclusion, this study provides the first demonstration that endogenous estrogens can physiologically inhibit germ cell growth in the male. This finding may have important implications concerning the potential action of environmental estrogens.

PROBABILISTIC ANALYSIS OF ANCHOR (DOWEL) PULL-OUT CAPACITY IN AERATED CONCRETE

2020 ◽  
pp. 25-29
Author(s):  
S. A. Soloviev ◽  
L. S. Shevcov
Keyword(s):  
Statistical Data ◽  
Probabilistic Approach ◽  
Experimental Studies ◽  
Reliability Theory ◽  
Pull Out ◽  
Concrete Blocks ◽  
Aerated Concrete ◽  
Statistical Approaches ◽  
The Given ◽  
Control Samples

Aerated concrete structures are widely used in construction as load-bearing or filler structures. The article describes the probabilistic approach to estimation of anchor (dowel) pull-out capacity. The article also presents the experimental studies of control samples from aerated concrete and diagrams “stress – strain”. The maximum permissible load values are obtained for the given batch of aerated concrete blocks based on the requirements of ensuring the specified reliability (probability of no-failure). Permissible load on the anchor (dowel) will also depend on the number of anchors in case of set of anchors as a conditional sequential mechanical system in terms of reliability theory. The design equations is given the reliability analysis of anchor (dowel) on pull-out force with limited statistical data and small number of control samples for using probabilistic and statistical approaches.

scholarly journals THE RESULTS OF STUDIES OF THE DEPENDENCE OF THE PERFORMANCE OF THE VIBRATING TWO-SHAFT CENTRIFUGAL MODULE ON THE MODE AND DESIGN PARAMETERS

2019 ◽  
pp. 5-10
Author(s):  
Vladimir Naduty ◽  
Anastasia Loginova ◽  
Vitaliy Sukharev
Keyword(s):  
Rock Mass ◽  
Vibration Amplitude ◽  
Experimental Studies ◽  
Design Parameters ◽  
Crushed Rock ◽  
Experimental Sample ◽  
Elastic Supports ◽  
Loaded Rock ◽  
The Given

The article presents a new design of a vibrating twin-shaft centrifugal module designed for grinding and classification of rock mass. In this design, in addition to grinding, the operation of classification or screening of the crushed mass was added, which does not allow its regrinding and increases the productivity of the device. This is achieved by installing in the bottom of the chamber grinding mesh with cells in accordance with the required class size. At the same time, the classification process is intensified by the presence of vibration from vibration exciters fixed on the camera body and the installation of the camera on elastic supports. The reciprocating horizontal vibrations of the chamber with a given amplitude and frequency contribute to the segregation of the crushed rock mass in the bed by size, which positively affects the efficiency of classification and grinding. The presence of vibration helps to unload the oversize product from the grinding chamber. Also, the article considers experimental studies performed on a vibrational two-shaft centrifugal module to determine the dependence of the performance of a given design on five variable factors: rotor shaft revolutions (n, rpm), size of the loaded rock mass (Δ, mm), rock mass strength (σ, kg/mm2), camera vibration frequency (ω, rpm) and its vibration amplitude (A, mm). Studies have shown the efficiency and increased productivity of the new design in relation to a centrifugal disintegrator without a classification grid and vibration. The results of the work allow us to recommend the design under study for the manufacture of an experimental sample according to the given initial requirements, and the established dependences (Q = f (n, Δ, σ, ω, A) make it possible to develop a mathematical model of the grinding process in this setup to calculate the required parameters.

scholarly journals METHODS FOR CALCULATING RECTANGULAR SECTION BEAMS MADE OF WOOD AND CONCRETE

2021 ◽  
pp. 1-5
Author(s):  
Ksenia Olegovna Dubrakova ◽  
Viacheslav Aseev ◽  
Aleksey Bulgakov
Keyword(s):  
Comparative Analysis ◽  
Concrete Beam ◽  
Concrete Beams ◽  
Rectangular Cross Section ◽  
Limit State ◽  
Experimental Studies ◽  
Ultimate Limit State ◽  
Numerical Comparison ◽  
Building Structures ◽  
Ultimate Limit

The research aimed to study methods for calculating wood-concrete beams of rectangular cross-section when testing building structures according to the ultimate limit state. The article focuses on the comparison of theoretical methods for calculating structures and considers several methods of fastening the samples of a typical wood-concrete beam. There were obtained experimental data of the ultimate limit state for each sample and carried out a comparative analysis of the most advantageous scheme of fastening the sample parts. The scientific novelty is in the development of an algorithm for calculating composite wood-concrete beams of rectangular cross-sections. As a result, numerical comparison of the values for calculating a typical wood-concrete beam using two of the methods under consideration was given, experimental studies were carried out, as well as a comparative analysis of the obtained theoretical and experimental results.

scholarly journals Mathematical modeling of filling the CCM mold with liquid metal during its supply from a rotating submersible nozzle

2021 ◽  
Vol 64 (4) ◽  
pp. 302-310
Author(s):  
V. I. Odinokov ◽  
A. I. Evstigneev ◽  
E. A. Dmitriev ◽  
S. Yu. Alexandrov ◽  
G. I. Usanov
Keyword(s):  
Mathematical Modeling ◽  
Liquid Metal ◽  
Steel Casting ◽  
Theoretical Calculations ◽  
Rectangular Cross Section ◽  
New Technology ◽  
Metal Flow ◽  
Experimental Studies ◽  
Equations Of Mathematical Physics ◽  
Difference Form

Experimental studies of the flow of liquid metal in CCM mold are long, complex and labor consuming process. Therefore, mathematical modeling by numerical methods is increasingly used for this purpose. The article considers a new technology for liquid metal supply into a mold. The authors present original patented design of the device, consisting of direct-flow and rotating bottom nozzles. The main results of investigations of the melt flow in the mold are considered. The objects of research were hydrodynamic and heat flows of liquid metal at new process of steel casting into a CCM mold of rectangular section. The result is spatial mathematical model describing flows and temperatures of liquid metal in the mold. To simulate the processes occurring during metal flow in the mold, special software was designed. Theoretical calculations are based on fundamental equations of hydrodynamics, equations of mathematical physics (equation of heat conduction taking into account mass transfer) and proven numerical method. The area under study was divided into elements of finite dimensions; for each element, resulting system of equations was written in difference form. The results are fields of velocities and temperatures of metal flow in the mold volume. A calculation program was compiled based on developed numerical schemes and algorithms. An example of calculation of steel casting into a mold of rectangular cross-section, and flow diagrams of liquid metal along various sections of the mold are given. Vector flows of liquid metal in different sections of the mold are clearly presented at different angles of rotation of the deep-bottom nozzle. The authors have identified the areas of intense turbulence. Metal flows of the described technological process were compared with traditional metal supply through a fixed bottom nozzle.

Sign in / Sign up

Export Citation Format

Share Document