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Dynamic interaction between clustered liquid propellant rocket engines under their asynchronous start-ups

Propulsion and Power Research 2021年第4期10卷 347-359页

作者： sergey I.Dolgopolov Olexiy D.Nikolayev Nataliia v.Khoriak Institute of Technical Mechanics of the National Academy of Sciences of Ukraine and the State Space Agency of Ukraine 15Leshko-Popel Str.Dnepr49600Ukraine

A nonlinear mathematical model of the low-frequency dynamics of the clustered multi-engine rocket propulsion system has been developed and the computations of the engine transient processes during the start-ups of the four-engine propulsion system with a shared feed system have been made *** on propulsion system start-up modeling the influence of the connectivity of engines in a cluster on the starting characteristics of individual engines is *** particular,an advanced nonlinear mathematical model of the pump cavitation phenomena is a distinctive feature of the mathematical *** computation results showed that the asynchronous engines start-ups during rocket lift-off lead to severely nonlinear engine transients and clustered engine thrust *** influence of the rocket engines asynchronous start-ups on the clustered feed system transients depends on many factors,mainly on from the clustered feed system low-frequency dynamics,the magnitude of the disturbance and the phase difference between disturbances acting on different branches of the feed *** deep lingering dips in the flow rate and pressure transients are possible due to the nonlinear dynamic interaction of the *** case of great pressure dips at the pump inlet(up to the pressure of saturated vapors during significant periods of start-up time)the cavitation breakdowns of the pumps of one or more engines from the cluster are *** can disrupt the operation of the entire propulsion system and leads to the failure of the launch vehicle mission.

关键词： Liquid propellant rocket engine Clustered engine thrust misbalance Nonlinear mathematical model Start-up transient Pump cavitation model Low-frequency processes Start-up sequence Shared feed system

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Seasonal variations in temperature sensitivity of soil respiration in a larch forest in the Northern Daxing’an Mountains in Northeast China

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Journal of Forestry Research 2022年第3期33卷 1061-1070页

作者： Lin Yang Qiuliang Zhang Zhongtao Ma Huijun Jin Xiaoli Chang sergey S.Marchenko valentin v.Spektor College of Forestry and Da Xing’anling Forest Ecosystem Research Station of Inner Mongolia Autonomous Region Inner Mongolia Agricultural UniversityHohhot010019People’s Republic of China Research-Station of Permafrost Geo-Environment Ministry of EducationInstitute of Cold Regions Science and Engineering and School of Civil EngineeringNortheast Forestry UniversityHarbin150040People’s Republic of China State Key Laboratory of Frozen Soils Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou730000People’s Republic of China Geophysical Institute University of Alaska FairbanksFairbanksAK99775USA Laboratory of General Geocryology Melnikov Permafrost InstituteSiberia BranchRussian Academy of SciencesYakutskRussia677010

Temperature sensitivity of respiration of forest soils is important for its responses to climate warming and for the accurate assessment of soil carbon budget. The sensitivity of temperature (T_(i)) to soil respiration rate (R_(s)), and Q_(10) defined by e^(10(lnRs−lna)/Ti) has been used extensively for indicating the sensitivity of soil respiration. The soil respiration under a larch (Larix gmelinii) forest in the northern Daxing’an Mountains, Northeast China was observed in situ from April to September, 2019 using the dynamic chamber method. Air temperatures (T_(air)), soil surface temperatures (T_(0cm)), soil temperatures at depths of 5 and 10 cm (T_(5cm) and T_(10cm), respectively), and soil-surface water vapor concentrations were monitored at the same time. The results show a significant monthly variability in soil respiration rate in the growing season (April–September). The Q_(10) at the surface and at depths of 5 and 10 cm was estimated at 5.6, 6.3, and 7.2, respectively. The Q_(10@10 cm) over the period of surface soil thawing (Q_(10@10 cm, thaw) = 36.89) were significantly higher than that of the growing season (Q_(10@10 cm, growth )= 3.82). Furthermore, the Rs in the early stage of near-surface soil thawing and in the middle of the growing season is more sensitive to changes in soil temperatures. Soil temperature is thus the dominant factor for season variations in soil respiration, but rainfall is the main controller for short-term fluctuations in respiration. Thus, the higher sensitivity of soil respiration to temperature (Q_(10)) is found in the middle part of the growing season. The monthly and seasonal Q_(10) values better reflect the responsiveness of soil respiration to changes in hydrometeorology and ground freeze-thaw processes. This study may help assess the stability of the soil carbon pool and strength of carbon fluxes in the larch forested permafrost regions in the northern Daxing’an Mountains.

关键词： Soil respiration Dynamic chamber method Ground thawing Major growth period Soil temperature

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Spiral attractor created by vector solitons

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Light(Science & Applications) 2014年第1期3卷 355-362页

作者： sergey v sergeyev Chengbo Mou Elena G Turitsyna Alexey Rozhin Sergei K Turitsyn Keith Blow Aston Institute of Photonic Technologies Aston UniversityBirmingham B47ETUK

Mode-locked lasers emitting a train of femtosecond pulses called dissipative solitons are an enabling technology for metrology,high-resolution spectroscopy,fibre optic communications,nano-optics and many other fields of science and ***,the vector nature of dissipative solitons has been exploited to demonstrate mode locked lasing with both locked and rapidly evolving states of ***,for an erbium-doped fibre laser mode locked with carbon nanotubes,we demonstrate the first experimental and theoretical evidence of a new class of slowly evolving vector solitons characterized by a double-scroll chaotic polarisation attractor substantially different from Lorenz,Ro¨ssler and Ikeda strange *** underlying physics comprises a long time scale coherent coupling of two polarisation *** observed phenomena,apart from the fundamental interest,provide a base for advances in secure communications,trapping and manipulation of atoms and nanoparticles,control of magnetisation in data storage devices and many other areas.

关键词： chaos mode-locked laser polarisation phenomena vector soliton

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Ballistic performance of titanium-based layered composites made using blended elemental powder metallurgy and hot isostatic pressing

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Defence Technology（防务技术） 2024年第9期39卷 1-14页

作者： Pavlo Markovsky Jacek Janiszewski Dmytro Savvakin Oleksandr Stasyuk Bartosz Fikus victor Samarov vianey Ellison sergey v.Prikhodko G.v.Kurdyumov Institute for Metal Physics of N.A.S.of Ukraine 36Academician Vernadsky BoulevardUA-03142 KyivUkraine Jarosław Dabrowski Military University of Technology 2Gen.Sylwester Kaliski Str.00e908 Warsaw 46Poland Synertech Inc. 11711 Monarch Street Garden GroveLos AngelesCA 92841USA Department of Materials Science and Engineering University of California Los AngelesLos AngelesCA 90095USA

Metal matrix composites tiles based on Ti-6Al-4v(Ti64)alloy,reinforced with 10,20,and 40(vol%)of either TiC or TiB particles were made using press-and-sinter blended elemental powder metallurgy(BEPM)and then bonded together into 3-layer laminated plates using hot isostatic pressing(HIP).The laminates were ballistically tested and demonstrated superior *** microstructure and properties of the laminates were analyzed to determine the effect of the BEPM and HIP processing on the ballistic properties of the layered *** effect of porosity in sintered composites on further diffusion bonding of the plates during HIP is analyzed to understand the bonding features at the interfaces between different adjacent layers in the *** ballistic performance of fabricated structures was explained by a significant reduction in the residual porosity of the BEPM products by their additional processing using HIP,which provides an unprecedented increase in the hardness of the layered *** is argued that the combination of the used two technologies,BEPM and HIP is principally complimentary for the materials in question with the abilities to solve the essential problems of each used individually.

关键词： Metal matrix composites Powder metallurgy Titanium hydride powder Master alloy Titanium carbide Titanium boride Hot isostatic pressing Ballistic tests

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A new aberrant species of the genus Sphaerostoma (Trematoda: Opecoelidae) from the Amur River basin

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Zoological Systematics 2024年第4期49卷 352-360页

作者： sergey G.Sokolov Sergei v.Shchenkov Evgeniy v.Frolov Sergei A.vlasenkov A.N.Severtsov Institute of Ecology and Evolution RAS Moscow 119071Russia Department of Invertebrate Zoology St.Petersburg State UniversitySt.Petersburg 199034Russia Sakhalin Branch of Russian Federal Research Institute of Fisheries and Oceanography Yuzhno-Sakhalinsk 693023Russia

A new freshwater opecoelid species,Sphaerostoma tamarae ***.,is described from Rhynchocypris percnura mantschurica caught in the Syumnyur River(Amur River basin,Russia).This parasite species differs from all other congeners in the distribution of the vitelline follicles(restricted to the hindbody)and the morphology of the ventral sucker(strongly protuberant).Molecular phylogenetic analysis based on 28S rRNA gene sequences and the morphological analysis allow to tentatively assign the new species to the genus Sphaerostoma,without closing the question regarding the true genus affiliation of this *** addition,the authors provide an argument for renaming the Plagioporinae to the Sphaerostomatinae.

关键词： Rhynchocypris Plagioporinae Sphaerostomatinae minnow

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Disease modifying treatment of spinal cord injury with directly reprogrammed neural precursor cells in non-human primates

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World Journal of Stem Cells 2021年第5期13卷 452-469页

作者： vladimir P Baklaushev Oleg v Durov vladimir A Kalsin Eugene v Gulaev sergey v Kim Ilya L Gubskiy veronika A Revkova Ekaterina M Samoilova Pavel A Melnikov Dzhina D Karal-Ogly sergey v Orlov Alexander v Troitskiy vladimir P Chekhonin Alexander v Averyanov Jan-Eric Ahlfors Biomedical Research Federal Research and Clinical Center of Specialized Medical Care and Medical TechnologiesFMBA of RussiaMoscow 115682MoskvaRussia Department of Neurosurgery Federal Research and Clinical Center of Specialized Medical Care and Medical TechnologiesFMBAMoscow 115682MoskvaRussia Department of Anesthesiology N.N.Blokhin Russian Cancer Research CentreMoscow 115478MoskvaRussia Radiology and Clinical Physiology Scientific Research Center Federal center of brain research and neurotechnologies of the Federal Medical Biological AgencyMoscow 117997Russia Department of Neurobiology Serbsky National Medical Research Center for Psychiatry and NarcologyMoscow 119992MoskvaRussia Department of Primatology Russian Acad Med SciResearch Institute of Medical PrimatologySochi 119992SochiRussia Department of vascular Surgery Federal Research and Clinical Center of Specialized Medical Care and Medical TechnologiesFMBA of RussiaMoscow 115682MoskvaRussia Department of Basic and Applied Neurobiology V.P.Serbsky Federal Medical Research Center for Psychiatry and NarcologyRussia Department of Medical Nanobiotechnology Pirogov Russian National Research Medical University(RNRMU)Moscow 115682MoskvaRussia New World Laboratories Laval H7V 4A7QuebecCanada

BACKGROUND The development of regenerative therapy for human spinal cord injury(SCI)is dramatically restricted by two main challenges:the need for a safe source of functionally active and reproducible neural stem cells and the need of adequate animal models for preclinical *** reprogramming of somatic cells into neuronal and glial precursors might be a promising solution to the first *** use of non-human primates for preclinical studies exploring new treatment paradigms in SCI results in data with more translational relevance to human *** To investigate the safety and efficacy of intraspinal transplantation of directly reprogrammed neural precursor cells(drNPCs).METHODS Seven non-human primates with verified complete thoracic SCI were divided into two groups:drNPC group(n=4)was subjected to intraspinal transplantation of 5 million drNPCs rostral and caudal to the lesion site 2 wk post injury,and lesion control(n=3)was injected identically with the equivalent volume of *** Follow-up for 12 wk revealed that animals in the drNPC group demonstrated a significant recovery of the paralyzed hindlimb as well as recovery of somatosensory evoked potential and motor evoked potential of injured *** resonance diffusion tensor imaging data confirmed the intraspinal transplantation of drNPCs did not adversely affect the morphology of the central nervous system or cerebrospinal fluid *** immunohistochemical analysis showed that drNPCs maintained SOX2 expression characteristic of multipotency in the transplanted spinal cord for at least 12 wk,migrating to areas of axon growth *** Our data demonstrated that drNPC transplantation was safe and contributed to improvement of spinal cord function after acute SCI,based on neurological status assessment and neurophysiological recovery within 12 wk after *** functional improvement described was not associated with neuronal differentiation of th

关键词： Direct cell reprogramming Neural precursor cells Directly reprogrammed neural precursor cells Spinal cord injury Nonhuman primates Regenerative therapy,Evoked potentials

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Efficient network immunization under limited knowledge

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National Science Review 2021年第1期8卷 127-134页

作者： Yangyang Liu Hillel Sanhedrai Gao Gao Dong Louis M.Shekhtman Fan Wang sergey v.Buldyrev Shlomo Havlin Department of Systems Science National University of Defense Technology Department of Physics Bar-Ilan University Faculty of Science Jiangsu University Network Science Institute Northeastern University Department of Physics Yeshiva University

Targeted immunization of centralized nodes in large-scale networks has attracted significant ***, in real-world scenarios, knowledge and observations of the network may be limited, thereby precluding a full assessment of the optimal nodes to immunize（or quarantine） in order to avoid epidemic spreading such as that of the current coronavirus disease（COvID-19） epidemic. Here, we study a novel immunization strategy where only n nodes are observed at a time and the most central among these n nodes is immunized. This process can globally immunize a network. We find that even for small n（≈10） there is significant improvement in the immunization（quarantine）, which is very close to the levels of immunization with full knowledge. We develop an analytical framework for our method and determine the critical percolation threshold p;and the size of the giant component P∞ for networks with arbitrary degree distributions P（k）. In the limit of n →∞ we recover prior work on targeted immunization, whereas for n = 1 we recover the known case of random immunization. Between these two extremes, we observe that, as n increases,p;increases quickly towards its optimal value under targeted immunization with complete information. In particular, we find a new general scaling relationship between |p;（∞）-p;（n）| and n as |p;（∞）-p;（n）| ～n;exp（-αn）. For scale-free（SF） networks, where P（k）～ k;, 2 ving knowledge of ≈log N nodes and immunizing the most optimal among them can dramatically reduce epidemic spreading. We also demonstrate our limited knowledge immunization strategy on several real-world networks and confirm that in these real networks, p;increases significantly even for small n.

关键词： percolation complex networks network immunization critical phenomena

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Safety of small and medium dams in permafrost regions

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Research in Cold and Arid Regions 2014年第4期6卷 331-339页

作者： Rudolf v.Zhang sergey A.velikin Melnikov Permafrost Institute Siberian Branch of the Russian Academy of SciencesYakutsk 677010 Russia vilyui Permafrost Research Station Melnikov Permafrost Institute Siberian Branch of the Russian Academy of SciencesChernyshevsky 678185 Russia

Safe operation and performance of dams is one of the key issues in permafrost regions. At present, the existing dams are 40–45 years old and they are reaching their design life limit. Intensive geocryological processes（thermokarst, thermal erosion, frost heaving, suffosion, concentrated seepage along the voids left by melt ice and others） begin to develop at the early stages of construction. These processes are even more intensive under severe climatic conditions of the permafrost zone due to the large thermal and moisture gradients and the resulting complex thermal stress-strain state in the structures. Determining safety criteria is a critical and difficult task in dam safety management. The existing procedures need to be continuously refined and improved depending on dam importance class. Some researchers recommend introducing process development criteria（stability, destabilization, and extremality） for more objective assessment of dam safety, in addition to the existing two condition criteria. In other words, they call for a multi-factor dam – environment interaction system. A case study of safety declaration for an existing dam is presented.

关键词： permafrost dam safety hydraulic structure geocryological process safety criteria safety declaration

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Direct patterning of reduced graphene oxide/graphene oxide memristive heterostructures by electron-beam irradiation

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Journal of Materials Science & Technology 2020年第3期38卷 237-243页

作者： Olesya O.Kapitanova Evgeny v.Emelin sergey G.Dorofeev Pavel v.Evdokimov Gennady N.Panin Youngmin Lee Sejoon Lee Lomonosov Moscow State University Leninskie gory119991 MoscowRussia Moscow Institute of Physics and Technology 9 Institutskiy per.DolgoprudnyMoscow Region141701Russia Institute of Microelectronics Technology and High-Purity Materials Russian Academy of SciencesChernogolovkaMoscow district142432Russia Nano Information Technology Academy Dongguk University-SeoulSeoul 04620Korea Quantum-Functional Semiconductor Research Center Dongguk University-SeoulSeoul 04620Korea Department of Semiconductor Science Dongguk University-SeoulSeoul 04620Korea

Memristive heterostructures,composed of reduced graphene oxide with different degree of reduction,were demonstrated through a simple method of‘direct electron-beam writing’on graphene *** with an electron beam at various doses and accelerating voltages made it possible to define highand low-conductivity graphene-oxide *** electron beam-reduced graphene oxide/graphene oxide heterostructure clearly exhibited a nonlinear behavior and a well-controlled resistive switching characteristic at a low operating-voltage range(v).The proposed memristive heterostructures are promising for highly-efficient digital storage and information process as well as for analogous neuromorphic computations.

关键词： Electron beam irradiation Reduced graphene oxide Graphene oxide Memristive heterostructure

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Writing with atoms： Oxygen adatoms on the MoO2/Mo（110） surface

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Nano Research 2013年第12期6卷 929-937页

作者： sergey A. Krasnikov Olaf Lubben Barry E. Murphy sergey I. Bozhko Alexander N. Chaika Natalia N. Sergeeva Brendan Bulfin and Igor v. Shvets Centre for Research on Adaptive Nanostructures and Nanodevices School of Physics Trinity College Dublin Dublin 2 Ireland Institute of Solid State Physics Russian Academy of Sciences Chernogolovka Moscow District 142432 Russia School of Chemistry University of Leeds Leeds LS2 9JT UK

Writing at the nanoscale using the desorption of oxygen adatoms from the oxygen-rich MoO2＋x/Mo（110） surface is demonstrated by scanning tunnelling microscopy （STM）. High-temperature oxidation of the Mo（110） surface results in a strained, bulk-like MOO2（010） ultra-thin film with an O-Mo-O trilayer structure. Due to the lattice mismatch between the Mo（110） and the MOO2（010）, the latter consists of well-ordered molybdenum oxide nanorows separated by 2.5 nm. The MoO2（010）/Mo（110） structure is confirmed by STM data and density functional theory calculations. Further oxidation results in the oxygen-rich MoOa^x/Mo（110） surface, which exhibits perfectly aligned double rows of oxygen adatoms, imaged by STM as bright protrusions. These adatoms can be removed from the surface by scanning （or pulsing） at positive sample biases greater than 1.5 v. Tip movement along the surface can be used for controlled lithography （or writing） at the nanoscale, with a minimum feature size of just 3 nm. By moving the STM tip in a predetermined fashion, information can be written and read by applying specific biases between the surface and the tip.

关键词： scanning tunnellingmicroscopy inelastic tunnelling atom manipulation molybdenum oxide

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