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Block Incremental dense Tucker decomposition with Application to Spatial and Temporal Analysis of Air Quality data

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Computer Modeling in Engineering & Sciences 2024年第4期139卷 319-336页

作者： SangSeok Lee HaeWon moon Lee Sael department of Artificial Intelligence Ajou UniversitySuwon-si16499Korea department of Software and Computer Engineering Ajou UniversitySuwon-si16499Korea

How can we efficiently store and mine dynamically generated dense tensors for modeling the behavior of multidimensional dynamic data?Much of the multidimensional dynamic data in the real world is generated in the form of time-growing *** example,air quality tensor data consists of multiple sensory values gathered from wide locations for a long *** data,accumulated over time,is redundant and consumes a lot ofmemory in its raw *** need a way to efficiently store dynamically generated tensor data that increase over time and to model their behavior on demand between arbitrary time *** this end,we propose a Block Incrementaldense Tucker decomposition(BId-Tucker)method for efficient storage and on-demand modeling ofmultidimensional spatiotemporal *** that tensors come in unit blocks where only the time domain changes,our proposed BId-Tucker first slices the blocks into matrices and decomposes them via singular value decomposition(SVd).The SVds of the time×space sliced matrices are stored instead of the raw tensor blocks to save *** modeling from data is required at particular time blocks,the SVds of corresponding time blocks are retrieved and incremented to be used for Tucker *** factor matrices and core tensor of the decomposed results can then be used for further data *** compared our proposed BId-Tucker with d-Tucker,which our method extends,and vanilla Tucker *** show that our BId-Tucker is faster than both d-Tucker and vanilla Tucker decomposition and uses less memory for storage with a comparable reconstruction *** applied our proposed BId-Tucker to model the spatial and temporal trends of air quality data collected in South Korea from 2018 to *** were able to model the spatial and temporal air quality *** were also able to verify unusual events,such as chronic ozone alerts and large fire events.

关键词： dynamic decomposition tucker tensor tensor factorization spatiotemporal data tensor analysis air quality

Converting TREx-RGB green-channel data to 557.7 nm auroral intensity:Methodology and initial results

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Earth and Planetary Physics 2024年第1期8卷 258-274页

作者： Jun Liang d.M.Gillies E.Spanswick E.f.donovan University of Calgary CalgaryT2N 1N4Canada

The recently deployed Transition Region Explorer(TREx)-RGB(red-green-blue)all-sky imager(ASI)is designed to capture“true color”images of the aurora and *** the 557.7 nm green line is usually the brightest emission line in visible auroras,the green channel of a TREx-RGB camera is usually dominated by the 557.7 nm *** this rationale,the TREx mission does not include a specific 557.7 nm imager and is designed to use the RGB green-channel data as a proxy for the 557.7 nm *** this study,we present an initial effort to establish the conversion ratio or formula linking the RGB green-channel data to the absolute intensity of 557.7 nm auroras,which is crucial for quantitative uses of the RGB *** illustrate two approaches:(1)through a comparison with the collocated measurement of green-line auroras from the TREx spectrograph,and(2)through a comparison with the modeled green-line intensity according to realistic electron precipitation flux measurements from low-Earth-orbit satellites,with the aid of an auroral transport *** demonstrate the procedures and provide initial results for the TREx-RGB ASIs at the Rabbit Lake and Lucky Lake *** RGB response is found to be *** conversion ratios or formulas between RGB green-channel data and the green-line auroral intensity are given and can be applied immediately by TREx-RGB data *** methodology established in this study will also be applicable to the upcoming SMILE ASI mission,which will adopt a similar RGB camera system in its deployment.

关键词： TREx RGB green-line aurora auroral transport model

The magnetosheath at high spectral resolution

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Earth and Planetary Physics 2024年第1期8卷 234-246页

作者： K.d.Küntz d.Koutroumpa W.R.dunn A.foster f.S.Porter d.G.Sibeck B.Walsh The Henry A.Rowland department of Physics and Astronomy Johns Hopkins University3701 San Martin DriveBaltimoreMD21218USA NASA Goddard Space flight Center 8800 Greenbelt RoadGreenbeltMD 20771USA LATMOS-OVSQ CNRSUVSQ Paris-SaclaySorbonne Université11 Boulevard d’Alembert78280GuyancourtFrance department of Physics and Astronomy University College LondonLondonUK The Centre for Planetary Science at UCL/Birkbeck Gower StreetLondon WC1E 6BTUK Center for Astrophysics Harvard University&Smithsonian Institution60 Garden StreetCambridgeMA 02138USA Center for Space Physics Boston University110 Cummington MallBostonMAUSA

While we eagerly anticipate SMILE’s(Solar wind Magnetosphere Ionosphere Link Explorer)unprecedented X-ray observations of the Earth’s magnetosheath and the initiation of a new era of magnetospheric research,it seems appropriate to look ahead to the abilities of the next generation of astrophysics *** these,the Line Emission Mapper(LEM),a large aperture micro-calorimeter based mission,is currently planned to be able to observe the magnetosheath at high spectral resolution(~2 eV).With a field of view of~30′,LEM will allow higher spatial resolution and higher cadence measurement of the motion of a very small portion of the magnetopause over relatively short periods of time(multiple hours),complementing SMILE’s global ***’s strength is its spectral *** will be able to measure the abundance of a broad range of elements and ionization states,many of which are inaccessible to current in situ instruments,and will be able to separate the emission from the magnetosheath from the emission from the cosmic X-ray background using the difference in their relative velocities.

关键词： magnetosheath charge exchange solar wind abundances

Localized-states quantum confinement induced by roughness in CdMnTe/CdTe heterostructures grown on Si(111) substrates

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Journal of Semiconductors 2024年第9期45卷 28-35页

作者： Leonarde N.Rodrigues Wesley f.Inoch Marcos L.f.Gomes Odilon d.d.Couto Jr. Bráulio S.Archanjo Sukarno O.ferreira Physics department Federal University of ViçosaViçosa36570-900Minas GeraisBrazil Instituto de física Gleb Wataghin Universidade Estadual de CampinasCampinas13083-859São PauloBrazil National Institute of Metrology Quality and Technology(Inmetro) Materials Metrology Division(DIMAT)Xerém2525-020Rio de JaneiroBrazil

This work shows that despite a lattice mismatch of almost 20%, CdMnTe/CdTe/CdMnTe heterostructures grown directly on Si(111) have surprisingly good optical emission properties. The investigated structures were grown by molecular beam epitaxy and characterized by scanning transmission electron microscopy, macro-and micro-photoluminescence. Low temperature macro-photoluminescence experiments indicate three emission bands which depend on the CdTe layer thickness and have different confinement characteristics. Temperature measurements reveal that the lower energy emission band (at 1.48 eV)is associated to defects and bound exciton states, while the main emission at 1.61 eV has a weak 2d character and the higher energy one at 1.71 eV has a well-defined (zero-dimensional, 0d) 0d nature. Micro-photoluminescence measurements show the existence of sharp and strongly circularly polarized (up to 40%) emission lines which can be related to the presence of Mn in the heterostructure. This result opens the possibility of producing photon sources with the typical spin control of the diluted magnetic semiconductors using the low-cost silicon technology.

关键词： CdMnTe/CdTe/CdMnTe heterostructure CdTe/CdMnTe quantum emitters quantum dot-like emission silicon(111)substrate

failure mechanism and simulation for long run-out of the catastrophic rock landslide in the Shanyang Vanadium Mine,China

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Journal of Mountain Science 2024年第9期21卷 2905-2917页

作者： LIU Yinpeng Mumtaz HAIdER david-darnor lawrence LI Tonglu SHEN Wei LI Ping College of Geological Engineering and Geomatics Chang’an UniversityXi’an 710054China Observation and Research Station of Water Cycle and Geological Environment for the Chinese Loess Plateau Ministry of EducationZhengning 745399China

On 12th August 2015,a massive rapid long run-out rock landslide occurred in the Shanyang Vanadium Mine in Shaanxi Province,China,which claimed the lives of 65 *** heavy rainfalls,earthquakes,and mining blasts were recorded before the ***,the failure mechanism and the cause of the long run-out movement are always in *** this paper,we conducted a detailed field investigation,laboratory tests,block theory analysis,and numerical simulation to investigate the failure and long run-out mechanisms of the *** field investigation results show that the source material of the rock landslide is a huge dolomite wedge block bedding on siliceous shale *** compression tests indicate that the uniaxial compression strength of the intact dolomite is 130-140MPa and the dolomite shows a brittle failure *** to the progressive downward erosion of the gully,the dolomite rock bridge at the slope toe became *** the compression stress in the dolomite bridge increased to surpass its strength,the brittle failure of the bridge *** huge potential energy was released following the disintegration of the landslide,which led to the high acceleration of this rock *** 3d discrete element simulation results suggest that the low intergranular friction contributes to the long run-out movement of this rock landslide.

关键词： Rock landslide Gully erosion Long run-out Wedge block discrete element method

Two-Stream Approximation to the Radiative Transfer Equation:A New Improvement and Comparative Accuracy with Existing Methods

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Advances in Atmospheric Sciences 2024年第2期41卷 278-292页

作者： f.Momo TEMGOUA L.Akana NGUIMdO dNJOMO Environmental Energy Technologies Laboratory(EETL) Faculty of SciencesUniversity of YaoundéPO Box 812 YaoundéCameroon department of Electrical and Electronic Engineering Faculty of Engineering and TechnologyUniversity of BueaPO Box 63 BueaCameroon

Mathematical modeling of the interaction between solar radiation and the Earth's atmosphere is formalized by the radiative transfer equation(RTE), whose resolution calls for two-stream approximations among other methods. This paper proposes a new two-stream approximation of the RTE with the development of the phase function and the intensity into a third-order series of Legendre polynomials. This new approach, which adds one more term in the expression of the intensity and the phase function, allows in the conditions of a plane parallel atmosphere a new mathematical formulation of γparameters. It is then compared to the Eddington, Hemispheric Constant, Quadrature, Combined delta function and Modified Eddington, and second-order approximation methods with reference to the discrete Ordinate(disort) method(δ –128 streams), considered as the most precise. This work also determines the conversion function of the proposed New Method using the fundamental definition of two-stream approximation(f-TSA) developed in a previous work. Notably,New Method has generally better precision compared to the second-order approximation and Hemispheric Constant methods. Compared to the Quadrature and Eddington methods, New Method shows very good precision for wide domains of the zenith angle μ 0, but tends to deviate from the disort method with the zenith angle, especially for high values of optical thickness. In spite of this divergence in reflectance for high values of optical thickness, very strong correlation with the disort method(R ≈ 1) was obtained for most cases of optical thickness in this study. An analysis of the Legendre polynomial series for simple functions shows that the high precision is due to the fact that the approximated functions ameliorate the accuracy when the order of approximation increases, although it has been proven that there is a limit order depending on the function from which the precision is lost. This observation indicates that increasing the order of app

关键词： Radiative Transfer Equation two-stream method Legendre polynomial optical thickness moments of specific intensity conversion function transmittance reflectance

Precipitation transformation pathway and mechanical behavior of nanoprecipitation strengthened fe-Mn-Al-C-Ni austenitic low-density steel

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Journal of Materials Science & Technology 2024年第7期174卷 157-167页

作者： Y.f.An X.P.Chen L.Mei P.Ren d.Wei W.Q.Cao College of Materials Science and Engineering Chongqing UniversityChongqing 400044China Guangxi Engineering Research Center for Characteristic Metallic Powder Materials School of Electronic EngineeringGuangxi University of Science and TechnologyLiuzhou 545006China Central Iron&Steel Research Institute Beijing 100081China

Precipitation strengthening has been widely adopted in austenitic low-density steel owing to excellent hardened *** approach generally employs the coherentκ′carbides and non-coherent B2 *** the precipitation transformation pathway is decisive for further optimizing the microstructures under specific engineering ***,the detailed precipitation sequence of fe-28Mn-11Al-1C-5Ni(wt%)austenitic low-density steel as well as its influence on mechanical prop-erties during aging process is systematically *** results reveal that nano-sizedκ′carbides domains(2 nm)exist in the solution-treated *** aging at 500℃for 1 h,the cuboidalκ′carbides(15-20 nm)uniformly disperse in austenite ***,after aging at 700℃for 15 min,the coarsenκ′carbides(30-35 nm)inhomogeneously distribute and align preferentially along the〈100〉***,extending the aging time to 60 min,the needle-type B2 particles replace theκ′carbides due to the enrichment of Ni elements at the phase boundaries among the austenite andκ′*** aging at 900℃,κ′carbides entirely dissolve into the austenite matrix,and the intragranular B2 particles are the sole precipitates in the austenite matrix and follow the K-S orientation relationship with *** work hardening capability seriously deteriorates due to the shearing ofκ′carbides by gliding *** the intragranular B2 particles preserve excellent work hardening rate by dislocations bow-out *** present work is meaningful for guiding the design of new generation dual-nano precipitation austenitic lightweight steel.

关键词： Lightweight steel κ′-carbides B2 particles Work hardening capability

Numerical analysis of high‑speed railway slab tracks using calibrated and validated 3d time‑domain modelling

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Railway Engineering Science 2024年第1期32卷 36-58页

作者： A.f.Esen O.Laghrouche P.K.Woodward d.Medina‑Pineda Q.Corbisez J.Y.Shih d.P.Connolly Institute for High‑Speed Rail and System Integration University of LeedsLeeds LS29JTUK Institute for Infrastructure and Environment Heriot-Watt UniversityEdinburgh EH144ASUK Alstom Transport Saint‑OuenFrance Birmingham Centre for Railway Research and Education University of BirminghamBirmingham B152TTUK

Concrete slabs are widely used in modern railways to increase the inherent resilient quality of the tracks,provide safe and smooth rides,and reduce the maintenance *** this paper,the elastic performance of a novel slab trackform for high-speed railways is investigated using three-dimensional finite element modelling in *** is then compared to the performance of a ballasted ***,slab and ballasted track models are developed to replicate the full-scale testing of track *** the models are calibrated with the experimental results,the novel slab model is developed and compared against the calibrated slab track *** slab and ballasted track models are then extended to create linear dynamic models,considering the track geodynamics,and simulating train passages at various speeds,for which the Ledsgard documented case was used to validate the *** travelling at low and high speeds are analysed to investigate the track deflections and the wave propagation in the soil,considering the issues associated with critical *** train loading methods are discussed,and the most practical approach is retained and ***,correlations are made between the geotechnical parameters of modern high-speed rail and conventional *** is found that considering the same ground condition,the slab track deflections are considerably smaller than those of the ballasted track at high speeds,while they show similar behaviour at low speeds.

关键词： High-speed railways Slab track New ballastless track Ballasted track Critical speeds finite element modelling Calibration of numerical models

design of a Novel Exoskeleton with Passive Magnetic Spring Self-locking and Spine Lateral Balancing

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Journal of Bionic Engineering 2024年第1期21卷 236-255页

作者： Jhon f.Rodríguez-León Betsy d.M.Chaparro-Rico daniele Cafolla francesco Lago Eduardo Castillo-Castañeda Giuseppe Carbone Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada Unidad Querétaro MecatronicaInstituto Politécnico NacionalCerro Blanco 14176090 Colinas del CimatarioQuerétaroMexico department of Mechanical Energy and Management EngineeringUniversity of CalabriaVia P.Bucci Cubo 46 C87036 RendeItaly faculty of Science and Engineering Department of Computer ScienceSwansea UniversitySwanseaUK CESTER University of Cluj-NapocaCluj-NapocaRomania

This paper proposes a new upper-limb exoskeleton to reduce worker physical *** proposed design is based on a novel PRRRP(P-Prismatic;R-Revolute)kinematic chain with 5 passive degrees of freedom(dof).Utilizing a magnetic spring,the proposed mechanism includes a specially designed locking mechanism that maintains any desired task *** proposed exoskeleton incorporates a balancing mechanism to alleviate discomfort and spinal torsional effects also helping in limb weight *** paper reports specific models and simulations to demonstrate the feasibility and effectiveness of the proposed *** experimental characterization is performed to validate the performance of the mechanism in terms of forces and physical strain during a specific application consisting of ceiling-surface drilling *** obtained results preliminarily validate the engineering feasibility and effectiveness of the proposed exoskeleton in the intended operation task thereby requiring the user to exert significantly less force than when not wearing it.

关键词： Assistive mechanism Exoskeleton Locking mechanism Bionic robot