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An advanced theoretical approach to study super-multiperiod superlattices:theory vs experiments

Journal of Semiconductors 2024年第2期45卷 57-66页

作者： Alexander Sergeevich Dashkov Semyon Andreevich Khakhulin Dmitrii Alekseevich Shapran Gennadii Fedorovich Glinskii Nikita Andreevich Kostromin Alexander Leonidovich Vasiliev Sergey Nikolayevich Yakunin Oleg Sergeevich Komkov Evgeniy Viktorovich Pirogov Maxim Sergeevich Sobolev Leonid Ivanovich Goray Alexei Dmitrievich Bouravleuv saint-petersburg Electrotechnical university"LETI" Saint Petersburg197022Russian Federation Alferov saint-petersburg National Research academic university of the russian academy of sciences Saint Petersburg194021RussiaFne deration saint petersburg Polytechnic university of Peter the Great Saint Petersburg195251Russian Federation Shubnikov Institute of Crystallography of Federal Scientific Research Centre“Crystallography and Photonics” Russian Academy of SciencesMoscow119333Russian Federation National Research Center‘Kurchatov Institute’ Moscow123182Russian Federation university associated with IA EAEC Saint Petersburg194044Russian Federation Institute for Analytical Instrumentation Saint Petersburg198095Russian Federation Ioffe Institute Saint Petersburg194021Russian Federation

A new theoretical method to study super-multiperiod superlattices has been *** method combines the precision of the 8-band kp-method with the flexibility of the shooting method and the Monte Carlo *** method was applied to examine the finest quality samples of super-multiperiod Al_(0.3)Ga_(0.7)As/GaAs superlattices grown by molecular beam *** express photoreflectance spectroscopy method was utilized to validate the proposed theoretical *** the first time,the accurate theoretical analysis of the energy band diagram of super-multiperiod superlattices with experimental verification has been *** proposed approach highly accurately determines transition peak positions and enables the calculation of the energy band diagram,transition energies,relaxation rates,and gain *** has achieved a remarkably low 5%error compared to the commonly used method,which typically results in a 25%error,and allowed to recover the superlattice *** retrieved intrinsic parameters of the samples aligned with XRD data and growth *** proposed method also accurately predicted the escape of the second energy level for quantum well thicknesses less than 5 nm,as was observed in photoreflectance *** new designs of THz light-emitting devices operating at room temperature were suggested by the developed method.

关键词： super-multiperiod superlattice photoreflectance spectroscopy Kane model kp-method energy band diagram light amplifiers

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Analysis of the X-ray emission of OB stars II: B stars

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Research in Astronomy and Astrophysics 2019年第8期19卷 143-150页

作者： Elizaveta Ryspaeva Alexander Kholtygin Crimean Astrophysical Observatory NauchnyCrimeaRussia saint-petersburg State university Saint-PetersburgRussia Institute of Astronomy Russian Academy of SciencesRussia

This paper is the second part of an investigation into the mechanism for the origin of X-rays in early-type stars. Archival X-ray observations of 25 B stars, obtained by the XMM-Newton satellite, are analysed. We check two hypotheses on the origin of X-ray emission: the Magnetically Confined Wind Shock Model(MCWS) and Pollock’s paradigm. For all studied stars, the mean ratio of the half widths at half maximum to the terminal velocities appears to be R ≈ 0.15-0.20 in contradiction to Pollock’s hypothesis that R ≈ 0.5. We checked three possible consequences of the MCWS model: correlations between the hardness of the X-ray spectra for B stars and terminal wind velocities, mass loss rates and magnetic *** was shown that such correlations are marginal or even absent both for magnetic and non-magnetic B stars.

关键词： stars:early-type stars:spectra:X-ray

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Satellite mapping of air temperature under polar night conditions

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Geo-Spatial Information Science 2022年第2期25卷 325-336页

作者： Kritsuk Sergei Victor Gornyy Tatiana Davidan Iscander Latypov Alexandra Manvelova Pavel Konstantinov Andrei Tronin Mikhail Varentsov Mikhail Vasiliev saint-petersburg Scientific Research Center for Ecological Safety Russian Academy of SciencesSaint-PetersburgRussia Faculty of Geography/Research Computing Center Lomonosov Moscow State UniversityMoscowRussia

A novel satellite technique for air temperature mapping with a spatial resolution of~100 m was proposed for the town of Apatity,the Kola Peninsula(Russia),taken as a case *** main idea behind this novel technique is to find the statistical relationships between the land surface temperatures in each point of the study area,observed by multiple infrared thermal satellite imagery,and the time series of air temperatures recorded by World Meteorological Organization(WMO)weather *** scenes of infrared thermal spectral band of the Landsat satellites for the period 2014–2019 were used,as well as the long-term time series of air temperature from the weather station and the results of air temperature observations carried out by the network of *** calm weather conditions,according to the ground truth,the error of air temperature mapping wasσ=1.5°C,and the precision was estimated asδ=1.0°*** analysis of the compiled air temperature map showed that,under polar night conditions,the air temperature on the hilltops was by 10–18°C higher than in the *** was concluded that,for economic reasons,as well as for the reasons of population health protection in the Arctic,it would be advisable to plan the placement of new cities on the *** of these new areas should be designed in a“semi-isolated”manner in order to minimize the time needed by the local people for crossing the lowlands between the nearby districts.A characteristic feature of modern megalopolises is their internal structure formed by the growing primary settlements that can be considered as nuclei interlinked by transportation ***,the new Arctic cities can be called“Arctic megalopolises”because of their internal structure that is specific to megalopolises.

关键词： Polar night town of Apatity air temperature satellite images time series regression mapping bioclimatic comfort

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Ion-conducting Membranes Based on Bacterial Cellulose Nanofibers Modified by Poly(sodium acrylate-co-2-acrylamido-2-methylpropanesulfonic acid)

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Chinese Journal of Polymer Science 2024年第3期42卷 333-343,I0007页

作者： Elizaveta V.Batishcheva Nikolay N.Smirnov Natalya V.Bobrova Maria P.Sokolova Michael A.Smirnov Institute of Macromolecular Compounds Russian Academy of SciencesBolshoy pr.31Saint Petersburg 199004Russia

Green method for preparation of ion-conducting membranes(ICM) based on bacterial cellulose nanofibers(CNF) modified by a copolymer of sodium acrylate and 2-acrylamido-2-methylpropanesulfonic acid was elaborated. FTIR and NMR data confirmed grafting of polyacrylate onto cellulose surface. Formation of porous structure of the ICM was controlled by SEM and AFM. The maximal ionic conductivity of the membranes reaches 1.5 and 3.1 mS·cm^(-1)(60 ℃ and 98% relative humidity) when they are saturated with water or H_2SO_4(1 mol·L^(-1)) electrolyte,respectively. Prepared ICM was tested as a separator in a symmetrical supercapacitor with electrodes based on polyaniline hydrogel. The assembled cell demonstrate ability to operate at high current density up to 100 A·g^(-1) maintaining specific capacitance 165 F·g^(-1). Maximal specific capacitance of 289 F·g^(-1) was achieved at current density 1 A·g^(-1). Retaining of 90% of initial capacitance after 10000 of charge-discharge cycles proves high electrochemical stability of prepared ICM.

关键词： Bacterial cellulose Ion conductivity Porous membrane Supercapacitor

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Self-healable and Robust Film Based on Electroactive Polymer Brush as Electrode for Flexible Supercapacitor

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Chinese Journal of Polymer Science 2024年第8期42卷 1049-1059页

作者： Maria P.Sokolova Vitaly K.Vorobiov Nikolay N.Smirnov Ivan S.Kuryndin Natalya V.Bobrova Michael A.Smirnov Institute of Macromolecular Compounds Russian Academy of SciencesBolshoy pr.31Saint Petersburg 199004Russia

The aim of this study was to develop self-healable and robust elect roconductive film based on polyaniline copolymer for application as electrode in flexible *** this purpose,the electroconductive polymer brushes(EPB)was *** synthesis of EPB is based on graft polymerizations of acrylamide(AAm)on poly(vinyl alcohol)(PVA)with formation of PVA-PAAm polymer brush and subsequent graft copolymerization of aniline and p-phenylenediamine on PVA-PAAm resulting in formation of EPB with electroconducting copoly(aniline-co-pphenylenediamine)(PAPh DA).It was found that the ratio between PVA and PAAm at the first stage greatly influence the electrochemical performance of the *** films were prepared by casting of EPB solution with subsequent *** of electrical current distribution through the film with AFM reveal more uniform distribution of PAPhDA in EPB in comparison with reference PVA-PAPhDA and PAAm-PAPhDA *** was demonstrated that mechanical cha racteristics and electrical conductivity values of films restore at large extent after curring and self-healing under optimal relative humidity level(58%).The flexile supercapacitor cell with EPB film electrodes demon strate specific capacitance 602 mF·cm^(-2)at the current density of 1 mA·cm^(-2)and retention 94%of initial capacitance after 5000 charge/discharge cycles.

关键词： Polymer brush Polyaniline Flexible supercapacitor Self-healing Electroconducting film

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Competitive Resource Allocation Among Urban Congestion Areas in a Modern Big City

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Journal of the Operations Research Society of China 2024年第1期12卷 133-153页

作者： Alexander Krylatov Anastasiya Raevskaya Institute of Applied Mathematical Research of the Karelian Research Centre of the russian academy of sciences Petrozavodsk185910Russia saint petersburg State university Saint Petersburg199034Russia

The continuing growth of modern big cities leads to their spatial expansion and the emergence of new road connections and urban *** where large transportation flows of pedestrians,passengers,and drivers come together create demand points,which attract business companies that strive to allocate their resources in the most sought-after ***,the law of supply and demand restrains companies from allocating all their resources solely in the most popular congestion areas since the more valuable an urban area,the higher the cost to be paid for a resource unit allocation *** a result,companies act in a non-cooperative manner and try to minimize their own overall costs when allocating resources across available commercial areas in a big ***-cooperative behavior of companies leads to the problem of Nash equilibrium search in the game of competing *** this paper,we study the corresponding resource allocation game under affine cost functions and obtain Nash equilibrium strategies in explicit *** findings allow us to develop a simple procedure for computing Nash equilibria in the game of companies allocating their resources among urban congestion *** computational study demonstrates the dependence of the average price for resource allocation on the number of players and their resource *** outcome of the paper contributes to flow theory and seems to be fresh and useful for managers.

关键词： Resource allocation Nash equilibrium Affine costs

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Photocurrent in the Polyfluorene Copolymer/PTCDI Heterojunction Enhanced by Reabsorption of Fluorescence Emission

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Chinese Journal of Polymer Science 2024年第12期42卷 1941-1947,I0009页

作者： Dmitriy A.Lypenko Alexey E.Aleksandrov Artem V.Dmitriev Anton A.Yakimanskiy Ilya E.Kolesnikov Tatiana G.Chulkova Alexander V.Yakimansky Alexey R.Tameev Frumkin Institute of Physical Chemistry and Electrochemistry of the russian academy of sciences 31/bld.4 Leninskiy ProspectMoscow119071Russia Institute of Macromolecular Compounds of the russian academy of sciences 31 Bolshoi pr.VOSaint Petersburg199004Russia saint petersburg State university 7/9 Universitetskaya nab.Saint Petersburg199034Russia

Copolyfluorenes are of great interest due to their ability to form thin films with tunable optical and electrical *** this paper,copolymers of polyfluorene with electron withdrawing dicyanostilbene and dicyanophenanthrene moieties were synthesized;their thin films were characterized by electron spectroscopy,cyclic voltammetry,electrical,and photoelectrical *** mobility of charge carriers in the copolymers was measured for the first time,with the acceptor components providing balanced electron and hole mobilities of the order of 10^(-6) cm^(2)·V^(-1)·s^(-1).Photodetectors based on the copolymer/PTCDI heterojunction exhibited the photoresponse band extended into the green region due to the absorption of PTCDI and an increased photocurrent in the UV-blue absorption band of the copolymer,which is related to the absorption of photoluminescent emission of the copolymers in *** presented approach to improving the performance of a polymer-based photodetector is promising in organic optoelectronics.

关键词： Polyfluorene copolymer Perylenedicarboximide derivative Charge carrier mobility Fluorescence Photoconductivity

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Synergistic effect of chitin nanofibers and polyacrylamide on electrochemical performance of their ternary composite with polypyrrole

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Journal of Energy Chemistry 2018年第3期27卷 843-853页

作者： Michael A.Smirnov Maria P.Sokolova Natalya V.Bobrova Alexander M.Toikka Pierfrancesco Morganti Erkki Lahderanta Lappeenranta university of Technology 53850 LappeenrantaFinland Institute of Macromolecular compounds Russian Academy of Sciences199004 Saint PetersburgRussia St.petersburg State university PeterhofSaint Petersburg 198504Russia Dermatological Institute II University of Naples80138 NaplesItaly

Development of simple methods for preparation of polymeric electrode materials with nanofibrous network structure is a perspective way toward cheap supercapacitors with high specific capacitance and energy density. In this work one-pot synthesis of electroactive ternary composite based on polypyrrole, polyacrylamide and chitin nanofibers with beneficial morphology was elaborated. Ternary system demonstrates better electrochemical performance in comparison with both polypyrrole–polyacrylamide and polypyrrole–chitin binary composites. Possible mechanism of synergistic effect of simultaneous influence of polyacrylamide and chitin nanofibers on the formation of composite＇s structure is *** highest attained specific capacitance of electroactive polypyrrole in ternary composite reached 249 F/g at 0.5 A/g and 150 F/g at 32 A/g. Symmetrical supercapacitor was assembled using the elaborated electrode material. High specific capacitance 89 F/g and good cycling stability with capacitance retention of 90% after 3000 cycles at 2 A/g were measured.

关键词： Energy materials Nanocomposites Natural fibers Electrical properties

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On a Heuristic Point of View Concerning the Mechanics and Electrodynamics of Moving Bodies

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World Journal of Mechanics 2016年第9期6卷 305-322页

作者： Leonid Filippov saint petersburg academic university of the russian academy of sciences Saint Petersburg Russia

The aspiration to clarify and visualize Einstein’s interpretation of the notion of simultaneity and relativistic understanding of length and time interval measurements led to the development of a model in which light pulses were replaced by sound signals. The model revealed the essence of Einstein’s mathematical constructs and the mechanism for origination of relativistic effects. Moreover, its consistent application produced novel results in particular, constructing a relativity theory based on derivation of its fundamentals out of a thought experiment. Using this approach, the ex-perimentally observed independence of the speed of light from the motion of source and observer was a necessary consequence of the finiteness of propagation speed for all kinds of in-formation. The paper provides a rationale for the logical framework formulated in article [1], and describes the experimental device built to validate the predictions of the theory and the results obtained.

关键词： Principle of Relativity Measurement Process Lorentz Group

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Heuristic Approach to Kinematics and Electrodynamics of Moving Bodies

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World Journal of Mechanics 2016年第3期6卷 52-83页

作者： Leonid Filippov saint petersburg academic university of the russian academy of sciences Saint Petersburg Russia

Relativity theory formulation is proposed, based not on the axiomatic postulation of its main principles but on their inference out of a thought experiment. With this approach, the experimentally observed independence of the speed of light from the motion of source and observer is a necessary consequence of the finiteness of propagation speed of all kinds of information. The mechanism of relativistic effects origination is described;the formulas of Lorentz transformations, Doppler quadratic effect, electromagnetic interaction and centrifugal force of inertia are derived.

关键词： The Principle of Relativity The Measurement Process Lorentz Group Doppler Effect Mach’s Principle

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