scholarly journals Influence of the binder technological shrinkage on the strength of composite reinforcement

2021 ◽  
Vol 350 ◽  
pp. 00001
Author(s):  
Vladimir Barsukov ◽  
Alla Volik ◽  
Sviatlana Sazon
Keyword(s):  
Experimental Studies ◽  
Mechanical Analysis ◽  
Educational Process ◽  
Published Data ◽  
Shrinkage Effect ◽  
Predictive Assessment ◽  
Reinforcement Bar ◽  
Polymer Shrinkage ◽  
Engineering Personnel ◽  
Composite Reinforcement

A structural and mechanical analysis of the effect of polymer binder technological shrinkage on the destruction mechanisms and strength at break of construction composite reinforcement has been carried out. Using the results of our own experimental studies, as well as published data of other researchers, the differences in the destruction mechanisms of fiberglass and carbon fiber reinforcement are shown. A calculated assessment of the polymer shrinkage effect in the anchor sleeve on the appearance of additional shrinkage stresses in the interface between the reinforcement bar and the test anchor sleeve has been made. The results obtained make it possible to modernize the methodology for predictive assessment of the strength of composite construction reinforcement and can be used by engineering and technical workers of manufacturers and consumers of such reinforcement, as well as in the educational process in the preparation of engineering personnel for the construction profile.

scholarly journals Structural Mechanics Aspect of Strength of Composite Reinforcement

2020 ◽  
Vol 212 ◽  
pp. 02002
Author(s):  
Vladimir Barsukov ◽  
Alla Volik ◽  
Svetlana Sazon
Keyword(s):  
Mechanical Analysis ◽  
Educational Process ◽  
Loading Capacity ◽  
Reinforcing Bars ◽  
Composite Construction ◽  
Lower Estimation ◽  
Design Production ◽  
Reinforcement Bar ◽  
Production And Operation ◽  
Composite Reinforcement

When operating in wet and corrosive conditions, composite reinforcement is in some cases an effective substitute for the suitable steel reinforcement. However, many questions related to its design, production and operation are insufficiently studied. The aim of the work is to create a methodology and carry out a comparative structural and mechanical analysis of strength indexes when working under load of coils and a bar of composite construction reinforcement. A method has been developed for analyzing the loading capacity of composite reinforcement according to the criteria of strength at rupture of a bar, as well as shear strength and bearing strength of its braid coils. Analytical and numerical modeling of conditions of equal strength of structural elements of composite construction reinforcement was carried out. Theoretically substantiated the assumption of a relatively low loading capacity of the braid coils in comparison with the loading capacity of the reinforcement bar. A predictive estimate of the conditions for ensuring the uniform strength of the bar for breaking and braid coils for shear and crushing by the method of lower estimation (for the minimum values of strength) has been carried out using the example of composite reinforcing bars produced by the industry of Republic of Belarus. In conclusion, results of work are formulated and it is noted that the results can be used by manufacturers and consumers of construction composite reinforcement, also in the educational process in the training of engineering personnel for the construction profile.

Thoracoabdominalis aortakirekesztés során fellépő elektrofiziológiai változások a gerincvelőben

2020 ◽  
Vol 73 (4) ◽  
pp. 160-166
Author(s):  
Csaba Dzsinich ◽  
Péter Gloviczki ◽  
Gabriella Nagy ◽  
Klaudia Vivien Nagy
Keyword(s):  
Spinal Cord ◽  
Motor Evoked Potentials ◽  
Spinal Cord Ischemia ◽  
Experimental Studies ◽  
Neuron Specific Enolase ◽  
Neurological Complications ◽  
Neurologic Outcome ◽  
Published Data ◽  
Aortic Clamping ◽  
Sensory Evoked

Összefoglaló. A thoracoabdominalis aortakirekesztés okozta gerincvelő ischemia súlyos neurológiai következményeit számos klinikai és kísérleti tanulmány bizonyítja. E nehezen kiszámítható, súlyos szövődmény megelőzésének érdekében régi törekvés megfelelő intra- és posztoperatív monitorizálás kifejlesztése, ami előre jelzi a gerincvelő-funkció romlását, illetve a kialakuló celluláris károsodást. A legelterjedtebb, a klinikai gyakorlatban széles körben alkalmazott megoldás a gerincvelői kiváltott motoros potenciál (MEP) folyamatos ellenőrzése. Ritkábban alkalmazott – bár ígéretes – eljárás a biokémiai változások nyomon követése, ami a sejtszintű károsodás markereit használja fel az ischemia okozta változások felismerésére. Korábbi dolgozatunkban kutyákon végzett kísérleteink azon eredményeit ismertettük, amelyekben a 60 perces thoracoabdominalis aortakirekesztés okozta neurológiai változások és a perfúzió adatainak összefüggéseit tárgyaltuk. Jelen tanulmányunkban a gerincvelői motoros (MEP) és szenzoros (SEP) kiváltott potenciálok változásait vizsgáljuk a neurológiai végállapot vonatkozásában. Megállapítottuk, hogy SEP változásai a neurológiai károsodás mértékével értékelhető összefüggést nem mutatnak. A MEP-amplitúdó és -latencia értékei biztonsággal jelzik a fenyegető gerincvelő ischemiát. A neurológiai deficit mélységét (Tarlov 2,1,0) a MEP-értékek változásai numerikusan nem értékelhetően követik. Summary. Severe neurological complications of the thoracoabdominal aortic clamping were published in numerous clinical and experimental studies. These hardly predictable, devastating consequences demanded to develop a monitoring system which might detect impending level of spinal cord ischemia in time – in order to introduce or enhance protective procedures and prevent permanent neurological deficit. The most widely used monitoring in clinical practice is the continuous surveillance of the motor evoked potentials (MEP) during and after thoracoabdominal aortic clamping. Much less used, but promising opportunity is to control the metabolic changes and cellular integrity utilizing specific markers like liquor lactate and neuron specific enolase (NSE) etc. In our earlier study we published data of our canine experiment related to coherencies between neurological outcome and specific perfusion of the spinal cord during and after one hour thoracoabdominal aortic clamping. In the present paper we investigate the behavior of motor evoked (MEP) and sensory evoked (SEP) potentials related to neurological changes. We conclude the behavior of SEP values hardly correlate with the neurologic outcome, meanwhile decrease of MEP amplitude provides reliable signal for developing spinal cord ischemia. We could not confirm a numeric correlation of these data and the level of the final neurologic outcome.

The Mechanical Analysis of the Composite Reinforced Circular Saw Blade

2011 ◽  
Vol 228-229 ◽  
pp. 484-489
Author(s):  
Xiao Ling Wang ◽  
Zhong Jun Yin ◽  
Chao Zhang
Keyword(s):  
Volume Fraction ◽  
Mechanical Analysis ◽  
Loading Conditions ◽  
Circular Saw ◽  
Model And Simulation ◽  
Circular Saw Blade ◽  
Saw Blade ◽  
Reinforcement Model ◽  
Circular Saws ◽  
Composite Reinforcement

Thinner saw blades cannot resist large lateral cutting forces due to their lower stiffness. In this paper we propose a composite reinforcement method to improve the mechanical properties of circular saw blades. We analyze and simulate the stress and strain fields of our proposed reinforced circular saws by Finite element method. Our analytical results contain not only influences of reinforcing parameters but also loading conditions on the lateral stiffness and the natural frequency of composite saw blades. Here the reinforcing parameters include: 1) the reinforcement location on circular saw blades, 2) the volume fraction of the reinforcements, 3) the number of the reinforcements; and loading conditions include: 1) the cutting force, 2) the rotational speed. Our composite reinforcement model and simulation results can contribute to a better design of circular saw blades.

scholarly journals Development of E-Learning in a Modern Technical University

2021 ◽  
Author(s):  
Sergey Kulik ◽  
◽  
Ivan Aladyshkin ◽  
Svetlana Kalmykova ◽  
Maria Odinokaya ◽  
...  
Keyword(s):  
Professional Training ◽  
Systematic Approach ◽  
Educational Process ◽  
Learning System ◽  
Educational Institutions ◽  
Learning Models ◽  
New Learning ◽  
E Learning ◽  
Coronavirus Infection ◽  
Engineering Personnel

The article is devoted to the increasing role and prospects for the development of e-learning in modern transformation of higher polytechnic education. In the context of preventing the spread of coronavirus infection COVID-19 and the transition of universities to various forms of distance education, this issue is of particular relevance. The aim of the study is to assess the process of introducing e-learning into the educational process of higher technical educational institutions in Russia. The methodological basis of the work was the analytical and systematic approach to the study of the object of research using methods of data systematization, evaluative analysis and forecasting, as well as logical generalization. The authors come to the conclusion that the introduction of e-learning in technical universities in Russia until recently played a supporting role in the reorganization and optimization of the processes of training engineering personnel. The development of e-learning helped to reduce the costs of the educational process, reduce the number of employees, as well as solve the problem of the classroom fund. An important role in the development of e-learning was played by the desire to increase the rating indicators. The desire to expand non-budgetary sources of funding for modern technical universities and the possibility of implementing new learning models were only additional incentives for expanding the e-learning system. The results of this study can be used in further studying the digitalization of higher education and assessing the prospects for the development of professional training in Russia.

scholarly journals The implementation of smartphones in the instructional process in the views of the female students at Hail University

2021 ◽  
Vol 8 (11) ◽  
pp. 30-36
Author(s):  
Laila Mohamed Sedky Genedy ◽  
Keyword(s):  
Standard Deviation ◽  
Learning Process ◽  
Experimental Studies ◽  
Female Students ◽  
Educational Process ◽  
Survey Method ◽  
Arithmetic Average ◽  
Instructional Process ◽  
The University ◽  
Descriptive Survey

This study aims to examine the implications of implementing smartphones in the educational process in the views of students at the University of Hail. The descriptive survey method was used in the research. To achieve the goal of the research, a questionnaire was prepared regarding the degree of use of smartphones in the learning process which is consisted of 20 paragraphs. The research sample was the female students at the University of Hail. It is found that the overall degree is medium as the arithmetic average is 3.34 with a standard deviation of 0.28. It was concluded that students are prodigiously interested in reviewing the university sites. Moreover, it was found that students are immensely skilled in using smartphones for the exchange of electronic messages and the exchange of information. However, they are less interested in submitting electronic assignments. Few students are watching educational presentations on smartphones because of their small size screens and high drainage from the batteries. Therefore, it is highly recommended to conduct experimental studies showing the importance of using the smartphone.

scholarly journals A new approach to assess the influence of road roughness on driver speed behavior based on driving simulator tests

2016 ◽  
Vol 11 (2) ◽  
pp. 144-152 ◽  
Author(s):  
Mariano Pernetti ◽  
Mauro D’Apuzzo Mauro D’Apuzzo ◽  
Francesco Galante
Keyword(s):  
Driving Simulator ◽  
Experimental Studies ◽  
Vertical Vibration ◽  
The Other ◽  
Added Value ◽  
Published Data ◽  
Vehicle Speed ◽  
Safety Level ◽  
The Road ◽  
Road Roughness

Vehicle speed is one of main parameters describing driver behavior and it is of paramount importance as it affects the travel safety level. Speed is, in turn, affected by several factors among which in-vehicle vibration may play a significant role. Most of speed reducing traffic calming countermeasures adopted nowadays rely on vertical vibration level perceived by drivers that is based on the dynamic interaction between the vehicle and the road roughness. On the other hand, this latter has to be carefully monitored and controlled as it is a key parameter in pavement managements systems since it influences riding comfort, pavement damage and Vehicle Operating Costs. There is therefore the need to analyse the trade-off between safety requirements and maintenance issues related to road roughness level. In this connection, experimental studies aimed at evaluating the potential of using road roughness in mitigating drivers’ speed in a controlled environment may provide added value in dealing with this issue. In this paper a new research methodology making use of a dynamic driver simulator operating at the TEST Laboratory in Naples is presented in order to investigate the relationship between the driver speed behavior on one hand, and the road roughness level, road alignment and environment, vehicle characteristics on the other. Following an initial calibration phase, preliminary results seem fairly promising since they comply with the published data derived from scientific literature.

scholarly journals Carbides and Nitrides of Zirconium and Hafnium

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2728 ◽  
Author(s):  
Sergey V. Ushakov ◽  
Alexandra Navrotsky ◽  
Qi-Jun Hong ◽  
Axel van de Walle
Keyword(s):  
Experimental Data ◽  
Phase Equilibria ◽  
Ab Initio ◽  
Solid Solutions ◽  
Binary Systems ◽  
Experimental Studies ◽  
Published Data ◽  
Oxygen Solubility ◽  
Melting Temperatures ◽  
Ab Initio Computations

Among transition metal carbides and nitrides, zirconium, and hafnium compounds are the most stable and have the highest melting temperatures. Here we review published data on phases and phase equilibria in Hf-Zr-C-N-O system, from experiment and ab initio computations with focus on rocksalt Zr and Hf carbides and nitrides, their solid solutions and oxygen solubility limits. The systematic experimental studies on phase equilibria and thermodynamics were performed mainly 40–60 years ago, mostly for binary systems of Zr and Hf with C and N. Since then, synthesis of several oxynitrides was reported in the fluorite-derivative type of structures, of orthorhombic and cubic higher nitrides Zr3N4 and Hf3N4. An ever-increasing stream of data is provided by ab initio computations, and one of the testable predictions is that the rocksalt HfC0.75N0.22 phase would have the highest known melting temperature. Experimental data on melting temperatures of hafnium carbonitrides are absent, but minimum in heat capacity and maximum in hardness were reported for Hf(C,N) solid solutions. New methods, such as electrical pulse heating and laser melting, can fill the gaps in experimental data and validate ab initio predictions.

An Experimental Study of Fluid Flow in Disk Cavities

1992 ◽  
Vol 114 (2) ◽  
pp. 454-461 ◽  
Author(s):  
S. H. Bhavnani ◽  
J. M. Khodadadi ◽  
J. S. Goodling ◽  
J. Waggott
Keyword(s):  
Experimental Study ◽  
Fluid Flow ◽  
Gas Turbine ◽  
Experimental Studies ◽  
Reynolds Numbers ◽  
Turbine Disk ◽  
Published Data ◽  
Disk System ◽  
Flow Rates ◽  
Pressure Distributions

Results are presented for an experimental study of fluid flow in models of gas turbine disk cavities. Experiments were performed on 70-cm-dia disks for rotational Reynolds numbers up to 2.29 × 106. Velocity and pressure distributions are presented and compared to previous theoretical and experimental studies for a free disk, and an unshrouded plane Rotor–Stator disk system. Minimum coolant flow rates for the prevention of ingress, determined for the case of a simple axial rim seal, compare well with previously published data.

Error propagation in the estimation of glomerular pressure from macromolecule sieving data

1995 ◽  
Vol 268 (4) ◽  
pp. F736-F745 ◽  
Author(s):  
A. Edwards ◽  
W. M. Deen
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Experimental Studies ◽  
Systematic Errors ◽  
Published Data ◽  
Hydraulic Pressure ◽  
Random Errors ◽  
True Value ◽  
Experimental Errors

The theoretical effects of the glomerular transmural hydraulic pressure difference (delta P) on the sieving coefficients (theta i) of macromolecules of varying size have led to a number of attempts to use sieving curves to estimate delta P noninvasively, with inconsistent results. The objective of this study was to determine the extent to which experimental errors and imperfections in the theoretical models limit the ability to obtain reliable estimates of delta P using this method. Our approach was to generate many sets of synthetic “experimental data” using computer simulations of glomerular sieving and to compute values of delta P by fitting models to those data in the presence of various types and magnitudes of errors. Unbiased experimental errors were simulated by adding random amounts to individual values of theta i, and systematic errors were investigated by using a model based on one type of pore-size distribution to fit “data” generated using a model of a different type. We found that with random errors in theta i only, the estimate of delta P was accurate to within +/- 4 mmHg nearly all of the time, provided that the standard deviation, sigma i, was < or = 5% of theta i. When there were also systematic errors arising from the use of an “incorrect” form of pore-size distribution, a useful predictor of success was the probability P that the residuals, the differences between the measured and predicted sieving coefficients, were randomly distributed. A value of P > 0.2, as calculated from the algebraic signs of the residuals, indicated a high likelihood that the pressure estimate was accurate, provided that the random errors were sufficiently small. When P > 0.2, the fitted value of delta P was within +/- 4 mmHg of the true value in about 90%, 80%, and 70% of the cases examined when sigma i was < or = 2%, 5%, or 10% of theta i, respectively. An analysis of published data from a number of experimental studies indicated, however, that the favorable conditions of small sigma i and large P are extremely difficult to achieve, making it unlikely that an accurate group-mean value of delta P will be estimated from any given set of sieving data. Significant experimental and theoretical advances will be needed to make this a reliable method for estimating glomerular pressure.

scholarly journals Oxygen-Enriched Diesel Engine Performance: A Comparison of Analytical and Experimental Results

1991 ◽  
Vol 113 (3) ◽  
pp. 365-369 ◽  
Author(s):  
R. R. Sekar ◽  
W. W. Marr ◽  
D. N. Assanis ◽  
R. L. Cole ◽  
T. J. Marciniak ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Heat Release ◽  
Experimental Studies ◽  
Engine Performance ◽  
Oxygen Enrichment ◽  
Published Data ◽  
Particulate Emissions ◽  
Lower Grade ◽  
Nox Emissions ◽  
Release Rates

Use of oxygen-enriched combustion air in diesel engines can lead to significant improvements in power density, as well as reductions in particulate emissions, but at the expense of higher NOx emissions. Oxygen enrichment would also lead to lower ignition delays and the opportunity to burn lower grade fuels. Analytical and experimental studies are being conducted in parallel to establish the optimal combination of oxygen level and diesel fuel properties. In this paper, cylinder pressure data acquired on a single-cylinder engine are used to generate heat release rates for operation under various oxygen contents. These derived heat release rates are in turn used to improve the combustion correlation—and thus the prediction capability—of the simulation code. It is shown that simulated and measured cylinder pressures and other performance parameters are in good agreement. The improved simulation can provide sufficiently accurate predictions of trends and magnitudes to be useful in parametric studies assessing the effects of oxygen enrichment and water injection on diesel engine performance. Measured ignition delays, NOx emissions, and particulate emissions are also compared with previously published data. The measured ignition delays are slightly lower than previously reported. Particulate emissions measured in this series of tests are significantly lower than previously reported.

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