scholarly journals ELECTROTECHNICAL COMPLEX FOR ELECTRODYNAMIC PROCESSING OF WELDED JOINTS

2020 ◽  
Vol 2020 (6) ◽  
pp. 61-68
Author(s):  
L.M. Lobanov ◽  
◽  
I.P. Kondratenko ◽  
V.M. Mikhalskyi ◽  
M.O. Pashchin ◽  
...  
Keyword(s):  
Current Pulse ◽  
Welded Joints ◽  
Single Channel ◽  
Experimental Studies ◽  
Compressive Force ◽  
Electrical Circuit ◽  
Simultaneous Action ◽  
Limited Area ◽  
Channel Switching ◽  
Electroplastic Effect

The composition of a two-channel switching power supply for electrodynamic processing of welded joints is determined, which consists in simultaneous action on a limited area of the electric current seam and compressive force of the electrode of such values that the electroplastic effect becomes possible. A linear electromechanical induction transducer is used to create the force pressure. The duration of the compressive phase of the power pulse is chosen to be longer than the duration of the current pulse, which reduces the probability of rupture of the electrical circuit and the release of thermal energy. By controlled delay of the beginning of the current pulse, synchronization of both factors of the electroplastic effect is achieved. The parallel inclusion of semiconductor devices that switch the discharge circuit alternately is proposed, which in the conditions of operation of electrical equipment with a pulse frequency of up to 10 Hz reduces the heat load. Experimental studies have shown a twofold increase in the number of cycles before the destruction of the samples with symmetrical bending. Comparison of two-channel and single-channel electrodynamic processing revealed a twofold reduction in power consumption in a two-channel device. References 8, figures 3, table 1.

Electric Current Pulse Welding of Titanium with 18-10 Stainless Steel

2009 ◽  
Vol 83-86 ◽  
pp. 1251-1253 ◽  
Author(s):  
E.G. Grigoryev ◽  
V.N. Bazanov
Keyword(s):  
Stainless Steel ◽  
Electric Current ◽  
Current Pulse ◽  
Contact Zone ◽  
Welded Joints ◽  
High Speed ◽  
Welded Joint ◽  
Electric Current Pulse ◽  
Pulse Effect ◽  
Different Thickness

The purpose of the work was to determine the capabilities of the pulse effect of electric current and pressure to produce welded joints of various component parts of different thickness from 18-10 stainless steel and titanium. Application of electric current pulses on the surfaces of contacting metallic conductors leads to considerable changes in the surface structure. Depending on the initial state of the surfaces and parameters of the pulse effect this can result in melting without formation of joints, formation of a strong welded joint with characteristics no worse than those of welded metals, and in destruction of the contact zone. A combination of a short electric pulse with simultaneous application of mechanical pressure in the weld zone causes high-speed deformation of the contact zone. The process of joint formation itself does not cause any appreciable diffusion during welding. The greatest energy emission and the maximal heating occur on the contacting surfaces being welded with the passage of an electric current pulse through the welding zone. Simultaneously with intensive heating, and due to applied pressure, high-speed deformation of materials takes place and a strong welded joint is formed. Optimal parameters for the welding of titanium and 18-10 stainless steel have been determined on the basis of the tests conducted. Investigations into the welding of titanium and 18-10 stainless steel have shown that application of a short electric current pulse and pressure produces stronger welded joints composed of both similar and different metals of considerably different thickness.

scholarly journals A meta-analysis of channel switching approaches for reducing zapping delay in internet protocol television

2021 ◽  
Vol 22 (3) ◽  
pp. 1476
Author(s):  
Timothy T. Adeliyi ◽  
Ropo E. Ogunsakin ◽  
Marion O. Adebiyi ◽  
Oludayo O. Olugbara
Keyword(s):  
Meta Analysis ◽  
Internet Protocol ◽  
Experimental Studies ◽  
Channel Switching ◽  
Major Bottleneck ◽  
Internet Protocol Television ◽  
Delay Component ◽  
Meta Analyses

Channel zapping delays are inconveniences that are often experienced by the subscribers of Internet protocol television (IPTV). It is a major bottleneck in the IPTV channels switching system that affect the quality of experience of users. Consequently, numerous channels switching approaches to minimize zapping delay in IPTV have been suggested. However, there is little knowledge reported in the literature on the determination of the strength of the evidence presented on the approaches of reducing zapping delay in IPTV, which is the prime purpose of this study. The extraction of the relevant articles was designed following the technique of preferred reporting items for systematic reviews and meta-analyses (PRISMA). All the included research articles were searched from the widely used databases of Google Scholar, and Web of Science. All statistical analyses were performed with the aid of the random-effects model implementation in Stata version 15. The overall pooled estimated delay component was presented in forest plots. Overall, thirteen studies were included in the meta-analysis and the overall pooled estimate was 10% (95% CI: 7%, 30%)). Experimental studies have shown that virtual elimination of IPTV zapping delay is possible for a relevant chunk of channel switching requests.

scholarly journals Evaluation of Delamination in Concrete by IE Testing Using Multi-Channel Elastic Wave Data

Sensors ◽  
2019 ◽  
Vol 20 (1) ◽  
pp. 201 ◽  
Author(s):  
Seong-Hoon Kee ◽  
Jin-Wook Lee ◽  
Ma. Doreen Candelaria
Keyword(s):  
Data Processing ◽  
Elastic Wave ◽  
Single Channel ◽  
Experimental Studies ◽  
Test Method ◽  
Wave Data ◽  
Wave Measurements ◽  
Propagating Waves ◽  
The Impact ◽  
Wave Modes

The main objectives of this study are to develop a non-destructive test method for evaluating delamination defects in concrete by the Impact-echo test using multi-channel elastic wave data and to verify the validity of the proposed method by experimental studies in the laboratory. First, prototype equipment using an eight-channel linear sensor array was developed to perform elastic wave measurements on the surface of the concrete. In this study, three concrete slab specimens (1500 mm (width) by 1500 mm (length) by 300 mm (thickness)), with simulated delamination defects of various lateral dimensions and depth, were designed and constructed in the laboratory. Multi-channel elastic wave signals measured on the three concrete specimens were converted to the frequency-phase velocity image by using the phase-shift method. A data processing method was proposed to extract the dominant propagating waves and non-propagating waves from the dispersion images. The dominant wave modes were used to evaluate delamination defects in concrete. It was demonstrated that the surface wave velocity values were useful for characterizing the shallow delamination defects in concrete. In addition, the peak frequency of non-propagating wave modes extracted from the dispersion images gives information on the lateral dimensions and depths of the delamination defects. This study also discussed the feasibility of combined use of the results from propagating and non-propagating wave modes to better understand the information on delamination defects in concrete. As will be discussed, the multi-channel elastic wave measurements enable more accurate, consistent, and rapid measurements and data processing for evaluation of delamination defects in concrete than the single-channel sensing method.

scholarly journals Determination of Strain and Stress Fields in Welded Joints of S960-QC Steel

2017 ◽  
Vol 62 (4) ◽  
pp. 2081-2087 ◽  
Author(s):  
T. Pała ◽  
I. Dzioba
Keyword(s):  
Welded Joints ◽  
Experimental Studies ◽  
Welding Process ◽  
Tensile Tests ◽  
Stress Fields ◽  
Uniaxial Tensile ◽  
Displacement Fields ◽  
The Individual ◽  
Computational Part

Abstract The paper presents the results of two butt welded joints by conventional method. The welding process was performed using a variety of linear welding energy. The studies included experimental and computational part. In experimental studies determined the distribution of hardness and mechanical properties of the individual analyzed sections of welded joints. The data obtained were intended to determine the extent of zones in the welded joints that have certain strength characteristics. Also conducted uniaxial tensile tests of welded joints with the registration of displacement fields on the surface of specimens by means of Aramis video-system what the final result are images of strain fields map on the surface of welded joints. The resulting strain values were compared with the results of numerical computations FEM.

THE NON-CLASSICAL PROBLEM OF AN ORTHOTROPIC BEAM OF VARIABLE THICKNESS WITH THE SIMULTANEOUS ACTION OF ITS OWN WEIGHT AND COMPRESSIVE AXIAL FORCES

2019 ◽  
Vol 53 (3 (250)) ◽  
pp. 183-190
Author(s):  
R.M. Kirakosyan ◽  
S.P. Stepanyan
Keyword(s):  
Collocation Method ◽  
Variable Thickness ◽  
Transverse Shear ◽  
Specific Problem ◽  
Classical Problem ◽  
Compressive Force ◽  
Simultaneous Action ◽  
Axial Forces ◽  
The Stability

thickness, the equations of the problem of bending of an elastically clamped beam in the case of simultaneous action of its own weight and axial compressive forces are obtained. The effects of transverse shear and the effect of reducing the compressive force of the support are taken into account. Turning to dimensionless quantities, the specific problem for a beam of linearly variable thickness is solved by the collocation method. The question of the stability of the beam is discussed.

scholarly journals Signal-to-signal neural networks for improved spike estimation from calcium imaging data

2021 ◽  
Vol 17 (3) ◽  
pp. e1007921
Author(s):  
Jilt Sebastian ◽  
Mriganka Sur ◽  
Hema A. Murthy ◽  
Mathew Magimai-Doss
Keyword(s):  
Correlation Coefficient ◽  
Calcium Imaging ◽  
Action Potentials ◽  
Single Channel ◽  
Imaging Techniques ◽  
Experimental Studies ◽  
Fluorescence Signal ◽  
Imaging Data ◽  
Operating Characteristics ◽  
Signal Conversion

Spiking information of individual neurons is essential for functional and behavioral analysis in neuroscience research. Calcium imaging techniques are generally employed to obtain activities of neuronal populations. However, these techniques result in slowly-varying fluorescence signals with low temporal resolution. Estimating the temporal positions of the neuronal action potentials from these signals is a challenging problem. In the literature, several generative model-based and data-driven algorithms have been studied with varied levels of success. This article proposes a neural network-based signal-to-signal conversion approach, where it takes as input raw-fluorescence signal and learns to estimate the spike information in an end-to-end fashion. Theoretically, the proposed approach formulates the spike estimation as a single channel source separation problem with unknown mixing conditions. The source corresponding to the action potentials at a lower resolution is estimated at the output. Experimental studies on the spikefinder challenge dataset show that the proposed signal-to-signal conversion approach significantly outperforms state-of-the-art-methods in terms of Pearson’s correlation coefficient, Spearman’s rank correlation coefficient and yields comparable performance for the area under the receiver operating characteristics measure. We also show that the resulting system: (a) has low complexity with respect to existing supervised approaches and is reproducible; (b) is layer-wise interpretable, and (c) has the capability to generalize across different calcium indicators.

scholarly journals Low-cycle fatigue of welded structures made from domestic and imported materials

2019 ◽  
Vol 80 (4) ◽  
pp. 75-79
Author(s):  
M. A. Vasechkin ◽  
S. V. Egorov ◽  
A. B. Kolomensky ◽  
E. D. Chertov
Keyword(s):  
Titanium Alloys ◽  
Welded Joints ◽  
Low Cycle Fatigue ◽  
Testing Machine ◽  
Simultaneous Action ◽  
Asymmetry Factor ◽  
External Loading ◽  
Cycle Fatigue ◽  
Corrosion Resistant ◽  
Stress Concentrators

In various branches of modern engineering, corrosion-resistant steels and titanium alloys are widely used as structural materials. At the same time, it is possible to connect parts made from domestic and imported alloys using automatic argon-arc electric welding, which leads to the formation of a material with unexplored properties in the weld. Welded joints are stress concentrators and currently there is no information about low-cycle fatigue of welded joints obtained by fusing domestic and imported materials. In the course of the research, the modes of welding and heat treatment of butt welded joints obtained from sheet titanium alloys and corrosion-resistant steel of domestic and foreign production have been developed. Resource tests for low-cycle fatigue of samples of welded joints were carried out. Tests on low-cycle fatigue were carried out on the upgraded testing machine UMM-10 with repeated static stretching with an asymmetry factor of +0.1 and at a frequency of 0.6–0.8 Hz. The maximum tensile stress was 80% of the temporary tensile strength of the weakest alloy in the pair. The main stress axis from external loading in all cases was perpendicular to the weld. The tests were carried out until the destruction of the sample. As a result of research, it was established that all welded joints were destroyed along the fusion line, which is explained by the simultaneous action of geometric and structural stress concentrators. In this case, the destruction of the samples, as a rule, began near the seam from the side of the weakest alloy in the pair. It was also established that the use of temperatures of incomplete annealing in comparison with the full one allows to increase the cyclic durability for welded joints of titanium alloys by 1.3–2 times. From the results of comparative tests of samples of corrosion-resistant steels, it follows that domestic and imported steels, as well as their welded joints, have similar properties, both in strength and in re-static durability.

scholarly journals Numerical investigation of the cope hole shape impact on fatigue life of welded joints in steel bridges

2019 ◽  
Vol 252 ◽  
pp. 07008
Author(s):  
Krzysztof Śledziewski
Keyword(s):  
Fatigue Life ◽  
Welded Joints ◽  
Hot Spot ◽  
Experimental Studies ◽  
Free Access ◽  
Steel Bridge ◽  
High Concentration ◽  
Hole Shape ◽  
Weld Toe ◽  
The Impact

Holes in the bridge girders are usually made at the joint of strips. In most cases, they are made when there is a need to make double-sided butt welds and in order to avoid welds crossing. Size of the hole is selected in order to allow full penetration of the strips across their whole width and also to ensure free access to the welds during NDT. Welded joints with holes, due to low fatigue life, are critical elements affecting durability of large-span steel bridge structures. Low fatigue life of joints with holes results mostly from high concentration of stresses near the weld toe caused by local reduction of cross-section. The paper covers parametric studies based on finite elements method in order to determine the impact of geometrical changes of the hole shape on distribution of stresses within probable areas of cracks initiation and durability of such joint. With reference to experimental studies results, four different holes geometries were analysed: semi-circle (conventional), triangle, parabola of second degree and oval. Assessment of the fatigue was performed using the so-called hot spot method, i.e. geometrical stresses. Results of the studies show that geometrical change of the hole shape affects the stresses concentration change, but it does not translate to the increase of fatigue life of such joint.

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