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Noise and vibration measurements in a Viking military vehicle

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Defence Technology（防务技术） 2021年第6期17卷 1976-1987页

作者： Gurmail S.Paddan Marietta l.l.McIlraith Institute of Naval Medicine Crescent RoadAlverstokeHampshirePO122DLUK Formerly at Institute of Naval Medicine Crescent RoadAlverstokeHampshirePO122DLUK

Noise and whole-body vibration measurements were made in a Viking military vehicle to determine the variation that should be expected during repeat measures,the effect of speed(up to 60 km/h in 5 km/h increments),and during travel over different types of terrain(comprising concrete road,gravel track and rough cross-country).Measurements were made at various crew positions(including the driver and commander)in both the front and the rear cabs in the *** translational axes of vibration were measured in each *** speeds were investigated over road(35 km/h and 55e60 km/h)and gravel(20 km/h and 35 km/h)*** effect of varying speed of the vehicle on the measured noise and vibration magnitudes was also *** highest sound pressure level(lAeq)of 104 dB(A)was measured at the commander’s standing position during travel over concrete road at 55 km/*** noise levels occurred for a standing commander compared with when sitting on the seat.A maximum single axis frequency-weighted vibration magnitude of 1.0 m/s^(2) *** measured on the driver’s seat during travel over track at 35 km/*** vibration magnitudes occurred during travel over track compared with travel over *** noise and vibration exposure of crew within the Viking vehicle increased with increasing speed of the vehicle.

关键词： Noise Whole-body vibration Vibration dose value Viking military vehicle

Waveform liDAR concepts and applications for potential vegetation phenology monitoring and modeling:a comprehensive review

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Geo-Spatial Information Science 2021年第2期24卷 179-200,I0001页

作者： Eric Ariel l Salas Agricultural Research Development Program(ARDP) Central State UniversityWilberforceUSA

Researchers continually demonstrated through published literature how liDAR could create unparalleled measurements of ecosystem structure and forest *** are a number of studies conducted utilizing waveform liDAR products for terrestrial monitoring,but those that deal specifically with the assessment of space-borne waveform liDAR for monitoring and modeling of phenology is very *** review highlights the waveform liDAR system and looks into satellite sensors that could link waveform liDAR and vegetation phenology,such as the proposed NASA’s Global Ecosystem Dynamics Investigation(GEDI)and the Japanese Experimental Module(JEM)-borne liDAR sensor named MOlI(Multi-footprint Observation lIDAR and Imager).Further,this work examines the richness and utility of the waveform returns and proposes a spline-function-derived model that could be exploited for estimating the leaf-shooting *** new approach may be utilized for ecosystem-level phenological studies.

关键词： Ecosystems gedi moli phenology vegetation modeling waveform liDAR

Applying machine learning to study fluid mechanics

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Acta Mechanica Sinica 2021年第12期37卷 1718-1726页

作者： Steven l.Brunton Department of Mechanical Engineering University of WashingtonSeattleWA 98195USA

This paper provides a short overview of how to use machine learning to build data-driven models in fluid *** process of machine learning is broken down into five stages:(1)formulating a problem to model,(2)collecting and curating training data to inform the model,(3)choosing an architecture with which to represent themodel,(4)designing a loss function to assess the performance of the model,and(5)selecting and implementing an optimization algorithm to train the *** each stage,we discuss how prior physical knowledge may be embedding into the process,with specific examples from the field of fluid mechanics.

关键词： Machine learning Fluid mechanics Physics-informed machine learning Neural networks Deep learning

Beyond COVID: Reframing the Global Problematique with STiP (Systems Thinking in Practice)

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Journal of Systems Science and Systems Engineering 2023年第1期32卷 1-15页

作者： Raymond l.Ison IFSR(International Federation for Systems Research)&Applied Systems Thinking in Practice(ASTiP)Group School of Engineering&InnovationThe Open UniversityWalton HallUK

Since 2019 humanity has been subjected to the perturbations of pandemic,economic disruption,war,civil unrest and changes in whole-Earth dynamics associated with a human-induced *** perturbation is like a wave-front breaking on the shore of our historical ways of thinking and acting,increasingly unfit for our human *** challenge to humanity is not *** 1970 the French term‘problematique’was coined to refer to a set of 49 interrelated global problems;the classic description of wicked and tame problems was published soon after,yet little progress has been made towards answering the question:what purposeful action will aid human flourishing,create and sustain a viable space for humanity,in our ongoing co-evolution with the Anthropocene-Biosphere?A case for innovation in our ways of knowing and doing is made based on arguments that our social world is constrained by:(i)explanations we accept that are no longer relevant to our circumstances;(ii)outdated historical institutions(in the institutional economics sense)that contribute as social technologies to a broader human created and ungoverned technosphere;(iii)inadequate theory-informed practices,or praxis,and(iv)governance-systems no longer adequate for *** of knowledge science and systems science are urged to act reflexively to critically evaluate the traditions-of-understanding out of which they think and act.

关键词： Cybersystemics governance systems reframing and framing critical social learning system

lONG-TIME ASYMPTOTIC OF STABlE DAWSON-WATANABE PROCESSES IN SUPERCRITICAl REGIMES

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Acta Mathematica Scientia 2019年第1期39卷 37-45页

作者： Khoa lê Department of Mathematical and Statistical Sciences University of Alberta Department of Mathematics South Kensington Campus Imperial College London

let W =(W_t)_(t≥0) be a supercritical a-stable Dawson-Watanabe process(withα∈(0,2]) and f be a test function in the domain of-(-△)^(α/2) satisfying some integrability condition. Assuming the initial measure W_0 has a finite positive moment, we determine the long-time asymptotic of arbitrary order of W_t(f). In particular, it is shown that the local behavior of Wt in long-time is completely determined by the asymptotic of the total mass W_t(1), a global characteristic.

关键词： Dawson-Watanabe process α-stable process

Unitary Scattering Protected by Pseudo-Hermiticity

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Chinese Physics letters 2022年第3期39卷 82-88页

作者： l.Jin School of Physics Nankai UniversityTianjin 300071China

Hermitian systems possess unitary ***,the Hermiticity is unnecessary for a unitary scattering although the scattering under the influence of non-Hermiticity is mostly *** we prove that the unitary scattering is protected by certain type of pseudo-Hermiticity and unaffected by the degree of *** energy conservation is violated in the scattering process and recovers after *** subsystem of the pseudo-Hermitian scattering center including only the connection sites is *** findings provide fundamental insights on the unitary scattering,pseudo-Hermiticity,and energy conservation,and are promising for light propagation,mesoscopic electron transport,and quantum interference in non-Hermitian systems.

关键词： scattering unitary protected

Nonplanar flow-induced vibrations of a cantilevered PIP structure system concurrently subjected to internal and cross flows

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Acta Mechanica Sinica 2019年第6期35卷 1241-1256页

作者： Z.Y.liu T.l.Jiang l.Wang H.l.Dai Department of Mechanics Huazhong University of Science and TechnologyWuhan 430074China Hubei Key laboratory for Engineering Structural Analysis and Safety Assessment Wuhan 430074China

Pipe-in-pipe(PIP)structures are widely used in offshore oil and gas pipelines to settle thermal insulation issues.A PIP structure system usually consists of two concentric pipes and one softer layer for thermal insulation *** total response of the system is related to the dynamics of both pipes and the interactions between these two concentric *** the current work,a theoretical model for flow-induced vibrations of a PIP structure system is proposed and analyzed in the presence of an internal axial flow and an external cross *** interactions between the two pipes are modeled by a linear distributed damper,a linear distributed spring and a nonlinear distributed spring along the pipe *** unsteady hydrodynamic forces due to cross flow are modeled by two distributed van der Pol wake *** nonlinear partial differential equations for the two pipes and the wake are further discretized by the aid of Galerkin’s technique,resulting in a set of ordinary differential *** ordinary differential equations are further numeri cally solved by using a fourth-order Runge-Kutta integration *** portraits,bifurcation diagrams,an Argand diagram and oscillation shape diagrams are plotted,showing the existence of a lock-in phenomenon and figure-of-eight *** PIP system subjected to cross flow displays some interesting dynamical behaviors different from that of a single-pipe structure.

关键词： Cantilevered PIP structure Theoretical model Flow-induced vibration Cross flow Internal flow

Melting, Oxidation, Evaporation of Particle in-Flight in Plasma Spray Processes

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Journal of Materials Science & Technology 2003年第Z1期19卷 49-52页

作者： H.B.Xiong l.l.Zheng Department of Mechanical Engineering State University of New York at Stony Brook Stony Brook NY 11794-2300 USA Department of Mechanical Engineering State University of New York at Stony Brook Stony Brook NY 11794-2300 USA

A comprehensive numerical model has been developed to investigate the transient behaviors of particle characteristics, such as temperature, melting, evaporation, and oxidation status during argon-hydrogen DC plasma *** model includes heat, momentum and mass transfer of carrier gas, and particle heating, melting, evaporationand oxidation. Special attentions have been paid to the evaporation-induced mass transfer and oxidation-inducedevaporation as well as variable non-continuum phenomena.

关键词： Melting, Oxidation, Materials processing, Multi-components reacting flow, Computational heat transfer

Focal distance tabu search

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Science China(Information Sciences) 2021年第5期64卷 5-16页

作者： Fred GlOVER Zhipeng lü Meta-Analytics Inc. School of Computer Science and Technology Huazhong University of Science and Technology

Focal distance tabu search modifies a standard tabu search algorithm for binary optimization by augmenting a periodic diversification step that drives the search away from a current best(or elite) solution until the objective function deteriorates beyond a specified threshold or until attaining a lower bound on the distance from the originating solution. The new augmented algorithm combines the threshold and lower bound approaches by introducing an initial focal distance for the lower bound which is updated when the diversification step is completed. However, rather than terminating the diversification step at the customary completion point, focal distance tabu search(TS) retains the focal distance bound through additional search phases designed to improve the objective function, drawing on a strategy proposed with strategic *** algorithm realizes this strategy by partitioning the variables into two sets which are managed together with an abbreviated tabu search process. An advanced version of the approach drives the search away from a collection of solutions rather than a single originating solution, introducing the concept of a signature solution to guide the search. The method can be employed to augment a variety of other metaheuristic algorithms such as those using threshold procedures, late acceptance hill climbing, iterated local search, breakout local search, GRASP, and path relinking.

关键词： tabu search diversification strategic oscillation adaptive partitioning metaheuristics