Журнал нано- та електронної фізики (Journal of nano- and electronic physics)
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Item Experimental results regarding the influence of initial ovality on local buckling under external pressure (collapse) of oil industry tubulars(Видавництво СумДУ, 2003) Dumitrescu, A.; Zisopol, D.G.An important load which can considerably affect the resistance capacity of oil industry tubulars (mainly casing and tubing in high pressure wells, and submarine pipelines installed in deep waters) is the external pressure, causing the pipe collapse phenomenon. Some of the factors with the greatest influence on pipe collapse behaviour are its geometrical imperfections (ovality, eccentricity, etc.). This paper presents the results of research activities aimed to investigate the influence of the pipe initial ovality on the external pressure collapse phenomenon, in order to define design methodologies and criteria for assessing the external pressure resistance capacity of oil industry tubulars. To that purpose, some tests have been performed on small scale pipe specimens, based on the similitude law, and their results have been compared with the calculation formulas usually used to assess pipe collapse resistance capacity considering the influence of initial ovality. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/10900Item Three-phased inverter analysis in linear modulated regime with weak inductive charge in triangle connection(Видавництво СумДУ, 2003) Cremenescu, Gh.The paper presents a framework for the analysis of the three-phased inverter functioning in linear modulated regime with weak inductive charge in triangle connection. The resistive – inductive charge with a power factor cosφ > 0,55 is defined as weak inductive. The recovery time of the reactive energy accumulated in the charge’s inductances is smaller than tact (an interval from a period). On the circuits configurated in the pulses of a tact one determines their equations in transitory regime and their solutions, and on the basis of some recurrent relations for the other tacts one determines the waveforms of the voltages and electric currents for a period. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/10895Item Simulation model of the mono-phased inverter with pulses width modulation(Видавництво СумДУ, 2003) Cremenescu, Gh.The article presents a model of pulse width modulation based on the assessment of a certain harmonic content of the inverter synthetic voltage. The commutation moments of the pulses (with the same amplitude but with different widths) are computed in the conditions when the fundamental of the synthetic voltage is equal to the proposed sinusoidal voltage, and the high harmonics up to order 4m – 2 are null. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/10890Item Input millimetric wave amplifiers for microcellular communications(Видавництво СумДУ, 2005) Sukhoruchko, O.N.; Belous, O.I.; Fisun, A.I.Работа посвящена созданию широкополостных входных усилительных устройств для современных телекоммуникационных систем КВЧ диапазона. Рассмотрена перспективная схема входного модуля с параметрическим усилением сигнала, состоящего из параметрического усилителя и генератора накачки. Благодаря моделированию колебательных процессов в так называемом сфероуголковоэшелетном открытом резонаторе, создан генератор накачки на ЛПД с уникальными шумовыми характеристиками. Удачное сочетание характеристик параметрического усилителя и твердотельного генератора накачки позволило создать входной модуль с пониженным уровнем шумов и предложить рекомендации по разработке входных цепей с усилением сигнала в диапазонах 60-100 ГГц. При цитуванні документа, використовуйте посилання http://essuir.sumdu.edu.ua/handle/123456789/10512Item Surfase morphology and optical properties of CdSe films obtained by the close-spaced vacuum sublimation technique(Видавництво СумДУ, 2009) Іващенко, Максим Миколайович; Иващенко, Максим Николаевич; Ivashchenko, Maksym Mykolaiovych; Опанасюк, Анатолій Сергійович; Опанасюк, Анатолий Сергеевич; Opanasiuk, Anatolii Serhiiovych; Starikov, V.V.; Perevertaylo, V.L.Investigation of the surface morphology, growth mechanisms and optical properties of CdSe films obtained by the close-spaced vacuum sublimation (CSVS) technique, which are promising for use as the absorption layers of tandem solar cells and photodetectors, was carried out in the present paper. Measurements of the optical characteristics of the layers were performed by the spectrophotometric analysis method near the “red boundary” of semiconductor photoactivity. Performed investigations allowed to obtain the spectral distributions of the transmission T(λ), reflection R(λ), absorption α(λ), and refraction n(λ) coefficients, and the real ε1(λ) and imaginary ε2(λ) parts of the optical dielectric constant of the samples and to define their dependence on the film deposition temperature. При цитуванні документа, використовуйте посилання http://essuir.sumdu.edu.ua/handle/123456789/9358Item Effect of the type of electrolyte аnion on the porous InP morphology obtained by the electrochemical etching(Видавництво СумДУ, 2009) Suchikova, Ya.A.; Kidalov, V.V; Sukach, G.A.In this work the analysis of the dependence of the porous InP morphology on the type of reacting anion is presented. It is shown that nanoporous InP layers are obtained under certain conditions of electrochemical etching. При цитуванні документа, використовуйте посилання http://essuir.sumdu.edu.ua/handle/123456789/9352Item physical and mechanical properties of the nanocomposite and combined Ti-N-Si /WC-Co-Cr and Ti-N-Si/(CR3C2)75-(NiCr)25 coatings(Видавництво СумДУ, 2009) Погребняк, Олександр Дмитрович; Погребняк, Александр Дмитриевич; Pohrebniak, Oleksandr Dmytrovych; Каверін, Михайло Валерійович; Каверин, Михаил Валерьевич; Kaverin, Mykhailo Valeriiovych; Il'yashenko, M.V.; Shypylenko, A.P.; Pshyk, A.V.; Beresnev, V.M.; Kirik, G.V.; Erdybayeva, N.K.; Makhmudov, N.A.; Kolisnichenko, O.V.; Tyurin, Yu.N.; Shpak, A.P.Two types of the combined nanocomposite coatings (Ti-N-Si /WC-Co-Cr and Ti-N-Si/ (Cr3C2Ni)75-(NiCr)25) of 160-320 μm thickness were produced using two deposition techniques: the cumulative-detonation and the vacuum-arc deposition with the high-frequency discharge. This gives the possibility (using the combined coatings) to restore the size of worn areas of the tools and demonstrate the high corrosion and wear resistance, to increase the hardness, modulus of elasticity, and plasticity index. Composition of the top coating varied from Ti = 60 at.%, N = 30 at.%, and Si = 10 at.% to Ti = 75 at.%, N = 20 at.%, and Si = 5 at.%. In the first series of coatings the following phases were obtained: (Ti;Si) and TiN in thin top coating and WC and W2C in thick bottom coating. The second series gives (Ti;Si)N and TiN in top coating; Cr3Ni2 and pure Cr in bottom coating; and small amount of Ti19O17 in the transition region between thin and thick coatings. For the first series the grain size achieved 25 nm at the hardness of 38 GPa. For the second series the grain size was 15 nm at the hardness of 42 GРa ± 4 GPa. It is shown that the corrosion resistance in salt solution and acid media increases with the wear decrease as a result of the cylinder friction over the surface of combined coating. При цитуванні документа, використовуйте посилання http://essuir.sumdu.edu.ua/handle/123456789/9351Item Grain-boundary diffusion in Cu and Ni films with thin metal coating(Видавництво СумДУ, 2009) Пчелінцев, Віктор Олександрович; Пчелинцев, Виктор Александрович; Pchelintsev, Viktor Oleksandrovych; Говорун, Тетяна Павлівна; Говорун, Татьяна Павловна; Hovorun, Tetiana Pavlivna; Проценко, Сергій Іванович; Проценко, Сергей Иванович; Protsenko, Serhii Ivanovych; Чорноус, Анатолій Миколайович; Чорноус, Анатолий Николаевич; Chornous, Anatolii MykolaiovychInvestigation results of the grain-boundary diffusion in Сu films with thin Ni coating and in Ni films with thin Cu coating by the low-temperature resistometric method are presented in this work. It is shown that during the coating deposition and thermal annealing the irreversible increase in the electrical resistance by the value from tenth parts to a few Ohms is observed. This is caused by the diffusion processes of coating atoms on the grain boundaries of base layers. При цитуванні документа, використовуйте посилання http://essuir.sumdu.edu.ua/handle/123456789/9350Item Properties of anisotropic stratified structure at the wave propagation along the interface(Видавництво СумДУ, 2009) Vytovtov, K.A.; Arkhipov, A.V.Plane-parallel anisotropic stratified structure is considered. Dependence of the reflection coefficient on the incident angle and anisotropic axis orientation is studied. It is proposed to use such structure as a valve and a frequency detector in the optical band. При цитуванні документа, використовуйте посилання http://essuir.sumdu.edu.ua/handle/123456789/9335Item Analysis of the thermal conditions of pulse impact avalanche transit-time diodes(Видавництво СумДУ, 2009) Sorokin, M.S.; Arkhipov, A.V.The nonstationary problem of the thermal process for the pulse mode of impact avalanche transit-time diodes is solved. The one-dimensional thermal model of such diodes, which takes into account the heterogeneity of the thermal power distribution and the heat spreading along the heat sink in the operating temperature range, is considered. The numerical calculation results of the average temperature of the active layer and the thermal resistance on the pulse parameters, as well as on the geometric and thermophysical diode parameters, are presented. При цитуванні документа, використовуйте посилання http://essuir.sumdu.edu.ua/handle/123456789/9333
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