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Mechanisms Modeling the Double Rotation of the Elytra in Beetles （Coleoptera）

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Journal of Bionic Engineering 2011年第4期8卷 395-405页

作者： leonid Frantsevich schmalhausen-Institute of Zoology B. Chmielnicki str. 15 Kiev-3 O 01601 Ukraine

We recorded transient movements, i.e. opening and closing, of beetle elytra. The beetles were tethered from below and filmed under a skew mirror; two markers were glued on each elytron at the apex and at the base. Body-fixed 3D traces of the apical and basal markers were reconstructed. The trace of the basal marker was, as a rule, non-parallel to the apical trace. The costal edge of the elytron uniformly supinated in the course of adduction of the apical marker. We found two essential attributes of double rotation：（1） the elytron to body articulation is approximately a spherical mechanism; （2） transient opening and closing possess single degree of freedom. The double rotation was modeled with two mechanisms：（1） a flexagon model of the Haas and Wootton＇s type simulated the elytral movement relative to the movement of one facet of the flexagon; （2） a screw and nut model provided traces as two sectors of a helical thread, one sector was phase shifted with respect to other one. screw guideways in a spherical mechanism give rise to discrepancies. Exact solution for a spherical mechanism with two guideways was proposed. The modeling revealed the attribute （3）： the elytron is actuated by two linked but differently directed drives. Experimental investigations on the elytron to body articulation may be oriented at search of those mechanisms.

关键词： insect flight insect thorax flexagon screw and nut joint

Computational study of laser fragmentation in liquid:Phase explosion,inverse Leidenfrost effect at the nanoscale,and evaporation in a nanobubble

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science China(Physics,Mechanics & Astronomy) 2022年第7期65卷 99-114页

作者： Hao Huang leonid V.Zhigilei school of Mechanical science and Engineering Huazhong University of Science and TechnologyWuhan 430074China Department of Materials science and Engineering University of VirginiaCharlottesville 22904-4745USA

Laser fragmentation in liquid is an effective and environment-friendly processing technique capable of yielding colloidal nanoparticles and atomic clusters with a narrow size distribution. The advancement of this technique can be facilitated by an improved understanding of processes that control the sizes, shapes, and structures of the produced nanoparticles. In this work, the dependence of the fragmentation mechanisms on the energy density deposited by the laser pulse is investigated in atomistic simulations performed for 20 nm Au nanoparticles irradiated in water by 10 ps laser pulses. The simulations reveal that the decrease in the absorbed laser energy leads to sequential transitions from the regime of “strong” phase explosion, when all products of an explosive phase decomposition of the irradiated nanoparticle are promptly injected into the water surrounding a nanobubble formed around the nanoparticle, to two distinct regimes of nanoparticle fragmentation leading to the formation of a large central nanoparticle surrounded by smaller satellite fragments. First, in the regime of “mild” phase explosion, the central nanoparticle is produced by the reflection of some of the hot metal droplets generated by the explosive decomposition of the nanoparticle from the boundary of the nanobubble. This reflection is attributed to the inverse Leidenfrost effect acting at the nanoscale. The reflected droplets converge in the center of the nanobubble and coalesce into a single droplet that solidifies shortly after the collapse of the nanobubble. Further decrease in the absorbed laser energy brings the irradiation conditions below the threshold for the phase explosion and results in the formation of a core-satellite structure of the fragmentation products through an interplay of the intense evaporation from the surface of the irradiated nanoparticle, evolution of the nanobubble, and condensation of the metal vapor into clusters and small satellite nanoparticles. The computationa

关键词： laser fragmentation in liquid molecular dynamics simulations phase explosion inverse Leidenfrost effect nanobubble nanoparticles

Nonlinear interference in crystal superlattices

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Light(science & Applications) 2020年第1期9卷 1239-1245页

作者： Anna V.Paterova leonid A.Krivitsky Institute of Materials Research and Engineering(IMRE) Agency for Science Technology and Research(A*STAR)138634 SingaporeSingapore

Nonlinear interferometers with correlated photons hold promise to advance optical characterization and metrology techniques by improving their performance and *** interferometers offer subshot noise phase sensitivity and enable measurements in detection-challenging regions using inexpensive and efficient *** sensitivity of nonlinear interferometers,defined by the ability to measure small shifts of interference fringes,can be significantly enhanced by using multiple nonlinear elements,or crystal ***,to date,experiments with more than two nonlinear elements have not been realized,thus hindering the potential of nonlinear ***,we build a nonlinear interferometer with up to five nonlinear elements,referred to as superlattices,in a highly stable and versatile *** study the modification of the interference pattern for different configurations of the superlattices and perform a proof-of-concept gas sensing experiment with enhanced *** approach offers a viable path towards broader adoption of nonlinear interferometers with correlated photons for imaging,interferometry,and spectroscopy.

关键词： spectroscopy nonlinear Nonlinear

Artificial intelligence applications in finance:a survey

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Journal of Management Analytics 2023年第4期10卷 676-692页

作者： Xuemei Li Alexander sigov leonid Ratkin leonid A.Ivanov Ling Li Department of Information Technology and Decision sciences Strome College of BusinessOld Dominion UniversityNorfolkVAUSA Department of Electronic Machinery University of Electronic Science and Technology of ChinaChengduPeople’s Republic of China Russian Technological University MoscowRussian Federation Russian Academy of sciences MoscowRussian Federation Russian Academy of Engineering MoscowRussian Federation

Finance is in our daily *** invest,borrow,lend,budget,and save *** also provides guidelines for corporation and government spending and revenue *** statistical solutions such as regression,PCA,and CFA have been widely used in financial forecasting and *** the increasing interest in artificial intelligence in recent years,this paper reviews the Artificial Intelligence(AI)techniques in the finance domain systematically and attempts to identify the current AI technologies used,major applications,challenges,and trends in *** explores AI-related articles in Finance in IEEE Xplore and EI compendex *** suggest AI has been engaged in Finance in financial forecasting,financial protection,and financial analysis and decision-making *** forecasting is one of the main sub-fields of Finance affected by AI *** major AI technology used is supervised *** learning has gained popular in recent *** could be used to address some emerging topics.

关键词： machine learning artificial intelligence finance

subcritical dynamo and hysteresis in a Babcock-Leighton type kinematic dynamo model

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Research in Astronomy and Astrophysics 2021年第10期21卷 250-256页

作者： Vindya Vashishth Bidya Binay Karak leonid Kitchatinov Department of Physics Indian Institute of Technology(BHU)Varanasi 221005India Institute of solar-Terrestrial Physics sB RAs Lermontov Str.126A664033IrkutskRussia Pulkovo Astronomical Observatory Pulkovskoe Sh.65St.Petersberg196140Russia

In the sun and sun-like stars,it is believed that cycles of the large-scale magnetic field are produced due to the existence of differential rotation and helicity in the plasma flows in their convection zones(CZs).Hence,it is expected that for each star,there is a critical dynamo number for the operation of a large-scale *** a star slows down,it is expected that the large-scale dynamo ceases to operate above a critical rotation *** our study,we explore the possibility of the operation of the dynamo in the subcritical region using the Babcock–Leighton type kinematic dynamo *** some parameter regimes,we find that the dynamo shows hysteresis behavior,i.e.,two dynamo solutions are possible depending on the initial parameters—decaying solution if starting with weak field and strong oscillatory solution(subcritical dynamo)when starting with a strong ***,under large fluctuations in the dynamo parameter,the subcritical dynamo mode is unstable in some parameter ***,our study supports the possible existence of subcritical dynamo in some stars which was previously demonstrated in a mean-field dynamo model with distributedαand MHD turbulent dynamo simulations.

关键词： magnetic field sun:activity sun:magnetic fields stars:rotation stars:dynamo stars

Ultrashort pulse laser ablation in liquids:probing the first nanoseconds of underwater phase explosion

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Light(science & Applications) 2022年第6期11卷 1005-1007页

作者： Chaobo Chen leonid V.Zhigilei Department of Materials science and Engineering University of Virginia395 McCormick RoadCharlottesvilleVA 22904-4745USA

The ultrafast pump-probe microscopy has shed new light on the complex dynamics of laser-induced explosive phase transformations and highlighted the importance of close integration of experimental,computational,and the... 详细信息

关键词： laser pump pulse

Tractable XML data exchange via relations

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Frontiers of Computer science 2012年第3期6卷 243-263页

作者： Rada CHIRKOVA leonid LIBKIN Juan L. REUTTER Department of Computer science North Carolina State University Raleigh NC 27606 USA school of Informatics University of Edinburgh Edinburgh EH8 9AB UK

We consider data exchange for XML documents： given source and target schemas, a mapping between them, and a document conforming to the source schema, construct a target document and answer target queries in a way that is consistent with the source information. The problem has pri- marily been studied in the relational context, in which data- exchange systems have also been built. since many XML documents are stored in relations, it is natural to consider using a relational system for XML data exchange. However, there is a complexity mismatch between query answering in relational and in XML data exchange. This indicates that to make the use of relational systems pos- sible, restrictions have to be imposed on XML schemas and mappings, as well as on XML shredding schemes. We isolate a set of five requirements that must be ful- filled in order to have a faithful representation of the XML data-exchange problem by a relational translation. We then demonstrate that these requirements naturally suggest the in- lining technique for data-exchange tasks. Our key contribu- tion is to provide shredding algorithms for schemas, docu- ments, mappings and queries, and demonstrate that they en- able us to correctly perform XML data-exchange tasks using a relational system.

关键词： data exchange XML XML shredding inlining

Dynamo saturation in rapidly rotating solar-type stars

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Research in Astronomy and Astrophysics 2015年第11期15卷 1801-1812页

作者： leonid L.Kitchatinov serge V.Olemskoy Institute for solar-Terrestrial Physics Pulkovo Astronomical Observatory

The magnetic activity of solar-type stars generally increases with stellar rotation rate. The increase, however, saturates for fast rotation. The Babcock-Leighton mechanism of stellar dynamos saturates as well when the mean tilt angle of active regions approaches ninety degrees. saturation of magnetic activity may be a consequence of this property of the Babcock-Leighton mechanism. stellar dynamo models with a tilt angle proportional to the rotation rate are constructed to probe this *** versions of the model- treating the tilt angles globally and using Joy＇s law for its latitude dependence- are considered. Both models show a saturation of dynamogenerated magnetic flux at high rotation rates. The model with latitude-dependent tilt angles also shows a change in dynamo regime in the saturation region. The new regime combines a cyclic dynamo at low latitudes with an（almost） steady polar dynamo.

关键词： saturation stellar latitude rotation rotating stars polar regime meridional consequence

Alkali control of high-grade metamorphism and granitization

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Geoscience Frontiers 2014年第5期5卷 711-727页

作者： Oleg G.safonov leonid Y.Aranovich Institute of Experimental Mineralogy RAs ChernogolovkaMoscow RegionRussia Department of Petrology Moscow State UniversityMoscowRussia Department of Geology.University of Johannesburg Johannesburg.south Africa Institute of Geology of Ore Deposits PetrographyMineralogy and Geochemistry

We review petrologic observations of reaction textures from high-grade rocks that suggest the passage of fluids with variable alkali activities. Development of these reaction textures is accompanied by regular compositional variations in plagioclase, pyroxenes, biotite, amphibole and garnet. The textures are interpreted in terms of exchange and net-transfer reactions controlled by the K and Na activities in the fluids. On the regional scale, these reactions operate in granitized, charnockitized, syenitized etc. shear zones within high-grade complexes. Thermodynamic calculations in simple chemical systems show that changes in mineral assemblages, including the transition from the hydrous to the anhydrous ones, may occur at constant pressure and temperature due only to variations in the H2O and the alkali activities. A simple procedure for estimating the activity of the two major alkali oxides, K2O and Na2O, is imple- mented in the TWQ software. Examples of calculations are presented for well-documented dehydration zones from south Africa, southern India, and sri Lanka. The calculations have revealed two end-member regimes of alkalis during specific metamorphic processes： rock buffered, which is characteristic for the precursor rocks containing two feldspars, and fluid-buffered for the precursor rocks without K-feldspar. The observed reaction textures and the results of thermodynamic modeling are compared with the results of available experimental studies on the interaction of the alkali chloride and carbonate-bearing fluids with metamorphic rocks at mid-crustal conditions. The experiments show the complex effect of alkali activities in the fluid phase on the mineral assemblages. Both thermodynamic calculations and experiments closely reproduce paragenetic relations theoretically predicted by D.s. Korzhinskii in the 1940s.

关键词： High-grade metamorphismAlkali activityFluidsReaction texturesFluid-mineral reactionsThermodynamic modeling