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45 results on '"Negrov, D. A."'

1. An Approximate Backpropagation Learning Rule for Memristor Based Neural Networks Using Synaptic Plasticity

Author

Negrov, D. V., Karandashev, I. M., Shakirov, V. V., Matveyev, Yu. A., Dunin-Barkowski, W. L., and Zenkevich, A. V.

Subjects
Computer Science - Neural and Evolutionary Computing, Computer Science - Emerging Technologies
Abstract

We describe an approximation to backpropagation algorithm for training deep neural networks, which is designed to work with synapses implemented with memristors. The key idea is to represent the values of both the input signal and the backpropagated delta value with a series of pulses that trigger multiple positive or negative updates of the synaptic weight, and to use the min operation instead of the product of the two signals. In computational simulations, we show that the proposed approximation to backpropagation is well converged and may be suitable for memristor implementations of multilayer neural networks., Comment: 21 pages, 6 figures, 1 table, title changed, manuscript thoroughly rewritten

Published
2015

6. Using advanced pressing technology for the wear resistance of polytetrafluoroethylene.

Author

Negrov, D. A. and Putintsev, V. Yu.

Subjects
*WEAR resistance, *MATERIALS science, *MECHANICAL wear, *AMPLITUDE modulation, *TECHNOLOGICAL innovations, *POLYTEF
Abstract

The development of new methods for obtaining materials with predetermined operational properties that ensure the durability and the wear resistance of friction units is an urgent problem in modern material science. The article considers the effect of ultrasonic pressing modes with simultaneously superimposed low-frequency amplitude modulation on the mechanical and tribotechnical properties of polytetrafluoroethylene. The comparison of the obtained research results of the new technology is carried out with the traditional pressing technology. The results of studies indicated that the technology of ultrasonic pressing with the simultaneous application of low-frequency amplitude modulation makes it possible to increase the mechanical properties of PTFE: the tensile strength by 15 %, elongation by 13 %, the elastic modulus by 8 %, the hardness by 12 %, while the intensity of the mass wear rate is reduced by 40 %, and the coefficient of friction by 27 %. [ABSTRACT FROM AUTHOR]

Published
2023
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14. The exploration of a structure change and properties of composite based on polytetrafluoroethylene activated by ultrasonic vibrations.

Author

Negrov, D. A., Eremin, E. N., and Putintsev, V. Yu.

Subjects
*ULTRASONICS, *WEAR resistance, *COMPOSITE materials, *POLYTEF, *FRICTION
Abstract

The article describes the influence of ultrasonic vibrations energy on the submolecular structure and tribotechnical properties of polymer composite materials based on polytetrafluoroethylene. Comparative analysis of the performed experiments showed that the introduction of ultrasonic vibration energy during pressing effects an increase in the wear resistance of polymer composite materials while maintaining low values of the coefficient of friction. In the friction process the submolecular structure changes because of a significant decrease in the size of crystallite blocks due to their fragmentation. [ABSTRACT FROM AUTHOR]

Published
2021
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21. Increasing the Hardness and Wear Resistance of Tungstenless Hard Alloy Working under the Abrasive Wear and Dynamic Loads.

Author

Akimov, V. V., Mishurov, A. F., Negrov, D. A., Putintsev, V. Yu., Pantyukhova, K. N., and Burgonova, O. Yu.

Subjects
WEAR resistance, FRETTING corrosion, HARDNESS, COMPOSITE materials, LEAD alloys, DYNAMIC loads
Abstract

The article considers way to increase the microhardness of the surface of tungstenless hard alloy based on titanium carbide with a binding phase of intermetallic titanium nickelide (TiNi). The matrix in solid composite materials must exhibit the capability to arbitrary form making during the deformation process of the composite and to strengthen its positions and good wet particulate, providing a strong bond along the phase boundaries and high density during sintering. The increase of strength properties and hardness of composite materials are achieved by improving the microstructure, repairing defects in their structure, while improving the wetting processes with the binder phase. It was established experimentally that the process of irradiating the surface of polished samples the ions Ar+ and Zr+ with energy about 20 keV and a dose of 1017 ions/cm² of a solid alloy leads to a significant change in the microhardness of the material. It happens due to the formation of quenching point defects occuring during intense heating and cooling of composite samples. Structure formation occurs in extremely non-equilibrium conditions of interaction of the surface of tungstenless alloy with a concentrated energy flow, during the implantation the samples of solid alloys. The data are presented, visually showing that increasing the strength and microhardness is promising way to increase the wear resistance of products intended for earth works related to drilling wells and laying tunnels. [ABSTRACT FROM AUTHOR]

Published
2019
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22. Development of Rational Heat Treatment Modes for Hot-Rolled Steel Bends.

Author

Pantyukhova, K. N., Burgonova, O. Yu., Negrov, D. A., and Putintsev, V. Yu.

Subjects
HEAT treatment, MANUFACTURING processes, STEEL, HEAT treatment of metals
Abstract

In this paper, the causes of the drop in the mechanical properties in the process of manufacturing the “bend-out” part are investigated. On the basis of the obtained results, non-standard heat treatment is proposed, allowing to increase the mechanical characteristics to the initial values. Experimental data showing the validity of the proposed heat treatment regimes are given. [ABSTRACT FROM AUTHOR]

Published
2019
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38. Technology of the production components of friction units from polymeric composite materials

Author

Negrov, D. A., Putintsev, V. U., Peredelskaya, O. A., and Naumova, A. V.

Subjects
677.494.743.41 [УДК 621.891], политетрафторэтилен, композит, polytetrafluoroethylene composite, ultrasonic pressing, ГРНТИ 55.39, УДК 620.22-419.8, ультразвуковое прессование
Abstract

Рассмотрено влияние режимов ультразвукового прессования на механические свойства полимерного композиционного материала на основе политетрафторэтилена и разработка технологии изготовления деталей узлов трения, методом ультразвукового прессования. В процессе ультразвукового прессования полимеров существенно облегчается возникновение и развитие пластической деформации частиц порошка, осуществляется активация дислокаций, происходящая в результате поглощения акустической энергии в местах дефектов кристаллической решетки и других структурных несовершенств. Вследствие этого за короткое время происходит локальный нагрев материала вокруг этих источников поглощения, увеличение молекулярной подвижности, что обусловливает более интенсивное развитие пластической деформации. Ультразвуковое воздействие может быть успешно использовано при твердофазной технологии получения (синтезе) полимерных композиционных материалов. Особенно это актуально для дисперснонаполненных модифицированных композиционных материалов на основе политетрафторэтилена (ПТФЭ). Совершенствование технологии получения модифицированного политетрафторэтилена в направлении приложения ультразвука большой интенсивности непосредственно при прессовании композита позволяет достичь существенного повышения его механических и триботехнических свойств. Целью данной работы является исследование влияния параметров ультразвукового прессования на механические свойства композиционного материала на основе политетрафторэтилена и разработка на этой основе технологии изготовления подшипников скольжения. Объектом исследования являлся композиционный материал на основе политетрафторэтилена с модифицирующей добавкой 5 масс. % гексагонального нитрида бора. Показано, что введение ультразвуковых колебаний в прессуемый материал приводит к повышению предела прочности и модуля упругости синтезируемого композита. Столь значительное повышение механических свойств, свидетельствует в первую очередь об изменении структуры композиционного материала, которое и приводит к повышению предела прочности и модуля упругости политетрафторэтилена модифицированного гексагональным нитридом бора. In the article is examined the influence of the regimes of ultrasonic extrusion on the mechanical properties of polymeric composite material on the basis of polytetrafluoroethylene and the development of the technology of the production of the components of friction units, by the method of ultrasonic extrusion. In the process of the ultrasonic extrusion of polymers significantly is facilitated appearance and development of the plastic deformation of the particles of the powder, is accomplished the activation of dislocations, proceeding as a result the absorption of acoustic energy in the places of the defects of crystal lattice and other structural imperfections. Because of this in short time occur the local heating of material around these sources of absorption, an increase in the molecular mobility, which causes the more intensive development of plastic deformation. Ultrasonic action can be successfully used for the solidphase technology of obtaining (synthesis) polymeric composite materials. Especially this is urgent for the dispernonapolnennykh modified composite materials on the basis of polytetrafluoroethylene (PTFE). The perfection of the technology of obtaining the modified politetrafluoroethylene in the direction of the application of the ultrasound of large intensity directly during the extrusion of composite makes it possible to reach a considerable increase in its mechanical and tribotechnical properties. The purpose of this work is a study of the influence of the parameters of ultrasonic extrusion on the mechanical properties of composite material on the basis of polytetrafluoroethylene and development on this the basis of the technology of the production of slide bearings. Composite material on the basis of polytetrafluoroethylene with modifying addition 5 mass. % of hexagonal nitride of boron was the subject of a study. It is shown that the introduction of ultrasonic fluctuations into the pressed material leads to an increase in the limit of strength and modulus of elasticity of the synthesized composite. So substantial increase in the mechanical properties, testifies first of all about the change in the structure of composite material, which leads to an increase in the limit of strength and modulus of elasticity of polytetrafluoroethylene of modified by hexagonal nitride boron Негров Дмитрий Анатольевич. Кандидат технических наук, доцент кафедры «Машиностроения и материаловедения», Омский государственный технический университет, negrov_d_a@mail.ru. Путинцев Виталий Юрьевич. Студент, Омский государственный технический университет, putintsev_vit@mail.ru. Передельская Ольга Андреевна. Студент, Омский государственный технический университет, olga.peredelskay@mail.ru. Наумова Анастасия Витальевна. Магистрант, Омский государственный технический университет, nase4karulit@nextmail.ru. D.A. Negrov, Omsk State Technical University, Omsk, Russian Federation, negrov_d_a@mail.ru, V.U. Putintsev, Omsk State Technical University, Omsk, Russian Federation, putintsev_vit@mail.ru, O.A. Peredelskaya, Omsk State Technical University, Omsk, Russian Federation, olga.peredelskay@mail.ru, A.V. Naumova, Omsk State Technical University, Omsk, Russian Federation, nase4karulit@nextmail.ru

Published
2015

44. Ferroelectric properties of full plasma-enhanced ALD TiN/La:HfO2/TiN stacks.

Author

Chernikova, A. G., Kuzmichev, D. S., Negrov, D. V., Kozodaev, M. G., Polyakov, S. N., and Markeev, A. M.

Subjects
ELECTRODES, FERROELECTRIC devices, METALS, ANNEALING furnaces, ELECTRIC potential, POLARIZATION (Electricity)
Abstract

We report the possibility of employment of low temperature (≤330 °C) plasma-enhanced atomic layer deposition for the formation of both electrodes and hafnium-oxide based ferroelectric in the metal-insulator-metal structures. The structural and ferroelectric properties of La doped HfO2-based layers and its evolution with the change of both La content (2.1, 3.7 and 5.8 at. %) and the temperature of the rapid thermal processing (550-750 °C) were investigated in detail. Ferroelectric properties emerged only for 2.1 and 3.7 at.% of La due to the structural changes caused by the given doping levels. Ferroelectric properties were also found to depend strongly on annealing temperature, with the most robust ferroelectric response for lowest La concentration and intermediate 650 °C annealing temperature. The long term wake-up effect and such promising endurance characteristics as 3x108 switches by bipolar voltage cycles with 30 µs duration and ±3 MV/cm amplitude without any decrease of remnant polarization value were demonstrated. [ABSTRACT FROM AUTHOR]

Published
2016
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45. Nonvolatile memory cells based on the effect of resistive switching in depth-graded ternary HfAlO oxide films.

Author

Orlov, O., Chuprik, A., Baturin, A., Gornev, E., Bulakh, K., Egorov, K., Kuzin, A., Negrov, D., Zaitsev, S., Markeev, A., Lebedinskii, Yu., and Zablotskii, A.

Subjects
HAFNIUM compounds, METALLIC oxides, PROTOTYPES, FLASH memory, SWITCHING circuits
Abstract

A nonvolatile memory cell prototype based on the effect of resistive switching in thin HfAlO oxide films grown by atomic layer deposition (ALD) with a Al depth-graded profile has been developed. This prototype imitates the arrangement of memory cells between the metallization layers of integral circuits. The obtained results are much superior to the parameters of conventional flash memory cells in increasing the reset speed and decreasing the reset voltage. [ABSTRACT FROM AUTHOR]

Published
2014
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