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Design and guidance of a multi-active debris removal mission

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Astrodynamics 2023年第4期7卷 383-399页

作者： Minduli C.Wijayatunga(b) Roberto Armellin harry Holt Laura Pirovano Aleksander A.Lidtke Te Pūnaha Atea–Space Institute The University of AucklandAuckland 1010New Zealand Astroscale Japan Inc. 1-16-4-16 KinshiSumida-kuTokyoJapan

Space debris have become exceedingly dangerous over the years as the number of objects in orbit continues to *** debris removal(ADR)missions have gained significant interest as effective means of mitigating the risk of collision between objects in *** study focuses on developing a multi-ADR mission that utilizes controlled reentry and *** mission comprises two spacecraft:a Servicer that brings debris to a low altitude and a Shepherd that rendezvous with the debris to later perform a controlled reentry.A preliminary mission design tool(PMDT)was developed to obtain time and fuel optimal trajectories for the proposed mission while considering the effect of J2,drag,eclipses,and duty *** PMDT can perform such trajectory optimizations for multi-debris missions with computational time under a *** guidance schemes are also studied,taking the PMDT solution as a reference to validate the design methodology and provide guidance solutions to this complex mission profile.

关键词： active debris removal(ADR) trajectory design optimization autonomous guidance low-thrust electric propulsion △u-law guidance Q-law guidance

Folding metamaterials with extremely strong electromagnetic resonance

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Photonics Research 2022年第9期10卷 2215-2222页

作者： harry MIYOSI SILALAHI WEI-FAN CHIANG YI-HONG SHIH WAN-YI WEI JOU-YU SU CHIA-YI HUANG Department of Applied Physics Tunghai UniversityTaichung 40704China Department of Photonics Taiwan Cheng Kung UniversityTainan 70101China

Aqueous solutions cannot be detected using transmissive terahertz metamaterials because water strongly absorbs terahertz *** terahertz metamaterials are easier to integrate terahertz emitters and receivers into single and compact devices than reflective terahertz *** detection of aqueous solutions using transmissive terahertz metamaterials is a big *** work fabricates a transmissive terahertz metamaterial using a folding metamaterial comprising split-ring resonators(SRRs)with nano-profiles with a high aspect ratio *** folding metamaterial has a small transmittance of-49 d b at its resonance frequency,large transmittance contrast of approximately 6×10^(4)with respect to the transmittance of its substrate,large refractive index sensitivity of 647 GHz/RIU,and large quality factor of *** result arises from the nano-profiles of the *** nanoprofiles increase the surface areas of the SRRs,increasing their surface currents and enhancing the electromagnetic resonance of the folding *** folding metamaterial detects a 188-μm-thick rabbit-blood layer that is deposited on it,which cannot be detected by using a common *** result reveals that folding metamaterials have potential in detecting the products of live microorganisms with geometrical sizes up to several hundreds of micrometers,such as hydrogen gas,hydrocarbons,and antibodies.

关键词： resonance sizes integrate

A robust WENO scheme for nonlinear waves in a moving reference frame

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Journal of Hydrodynamics 2016年第3期28卷 482-488页

作者： Stavros KONTOS harry b.bINGHAM Ole LINDbErg Allan P.ENGSIG-KARUP Department of Mechanical Engineering Technical University of DenmarkDenmark Department of Applied Mathematics and Computer Science Technical University of DenmarkDenmark

For robust nonlinear wave simulation in a moving reference frame, we recast the free surface problem in Hamilton-Jacobi form and propose a Weighted Essentially Non-Oscillatory （WENO） scheme to automatically handle the upwinding of the convective term. A new automatic procedure for deriving the linear WENO weights based on a Taylor series expansion is introduced. A simplified smoothness indicator is proposed and is shown to perform well. The scheme is combined with high-order explicit Runge-Kutta time integration and a dissipative Lax-Friedrichs-type flux to solve for nonlinear wave propagation in a moving frame of reference. The WENO scheme is robust and less dissipative than the equivalent order upwind-biased finite difference scheme for all ratios of frame of reference to wave propagation speed tested. This provides the basis for solving general nonlinear wave-structure interaction problems at forward speed.

关键词： nonlinear waves Weighted Essentially Non-Oscillatory (WENO) finite difference

3D U-Net Segmentation Improves Root System Reconstruction from 3D MRI Images in Automated and Manual Virtual Reality Work Flows

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Plant Phenomics 2023年第3期5卷 598-611页

作者： Tobias Selzner Jannis Horn Magdalena Landl Andreas Pohlmeier Dirk Helmrich Katrin Huber Jan Vanderborght harry Vereecken Sven behnke Andrea Schnepf Forschungszentrum Juelich GmbH Agrosphere(IBG-3)JuelichGermany Autonomous Intelligence Systems Group University of BonnBonnGermany Forschungszentrum Juelich GmbH Juelich Supercomputing CenterJuelichGermany

Magnetic resonance imaging(MRI)is used to image root systems grown in opaque ***,reconstruction of root system architecture(RSA)from 3-dimensional(3D)MRI images is *** resolution and poor contrast-to-noise ratios(CNRs)hinder automated ***,manual reconstruction is still widely ***,we evaluate a novel 2-step work flow for automated RSA *** the first step,a 3D U-Net segments MRI images into root and soil in *** the second step,an automated tracing algorithm reconstructs the root systems from the segmented *** evaluated the merits of both steps for an MRI dataset of 8 lupine root systems,by comparing the automated reconstructions to manual reconstructions of unaltered and segmented MRI images derived with a novel virtual reality *** found that the U-Net segmentation offers profound benefits in manual reconstruction:reconstruction speed was doubled(+97%)for images with low CNR and increased by 27%for images with high *** root lengths were increased by 20%and 3%,***,we propose to use U-Net segmentation as a principal image preprocessing step in manual work *** root length derived by the tracing algorithm was lower than in both manual reconstruction methods,but segmentation allowed automated processing of otherwise not readily usable MRI ***,model-based functional root traits revealed similar hydraulic behavior of automated and manual *** studies will aim to establish a hybrid work flow that utilizes automated reconstructions as scaffolds that can be manually corrected.

关键词： Root utilize otherwise

Propulsive matrix of a helical flagellum

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Chinese Physics b 2014年第11期23卷 51-56页

作者：张何朋刘斌 bruce Rodenborn harry L.Swinney Department of Physics and Astronomy and Institute of Natural Sciences School of Natural Sciences University of California Department of Physics and Center for Nonlinear Dynamics University of Texas at Austin

We study the propulsion matrix of bacterial flagella numerically using slender body theory and the regularized Stokeslet method in a biologically relevant parameter regime. All three independent elements of the matrix are measured by computing propulsive force and torque generated by a rotating flagellum, and the drag force on a translating flagellum. Nu- merical results are compared with the predictions of resistive force theory, which is often used to interpret micro-organism propulsion. Neglecting hydrodynamic interactions between different parts of a flagellum in resistive force theory leads to both qualitative and quantitative discrepancies between the theoretical prediction of resistive force theory and the numerical results. We improve the original theory by empirically incorporating the effects of hydrodynamic interactions and propose new expressions for propulsive matrix elements that are accurate over the parameter regime explored.

关键词： low-Reynolds-number flows micro-organism dynamics bacterial swimming

The Local Asymptotic behavior of Solutions of Second Order Linear Differential Equations in a Nutshell

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Journal of Mathematical Research with Applications 1993年第3期 337-350页

作者： harry Gingold Dept.of Math College of Arts and Sciences Morgantown:WV26505 U.S.A.

*** a second order linear differential equation with meromorphic coefficienta（x）y”+b（x）y’+c（x）y=0 （1.1）in,a domain D the local analytic theory for such equations is well developed,see e.g.[8].If xis a regular point for（1.1）then the theory advocates to utilize Taylor seriesexpansions of two linearly indepentdent solutions of（1.1）.If xis a regular singular pointfor（1.1）,Frobenius’method tells us to follow sometimes a laborious procedure which

关键词： exp The Local Asymptotic behavior of Solutions of Second Order Linear Differential Equations in a Nutshell

Dextran sulfate sodium-induced colitis-associated neoplasia:a promising model for the development of chemopreventive interventions

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Acta Pharmacologica Sinica 2007年第9期28卷 1450-1459页

作者： Margie Lee CLAPPER harry Stanley COOPER Wen-Chi Lee CHANG Divisions of Population Science Medical Science Fox Chase Cancer CenterPhiladelphiaPA 19111USA

Individuals diagnosed with ulcerative colitis face a significantly increased risk ofdeveloping colorectal dysplasia and cancer during their *** date,littleattention has been given to the development of a chemopreventive interventionfor this high-risk *** mouse model of dextran sulfate sodium (DSS)-induced colitis represents an excellent preclinical system in which to both charac-terize the molecular events required for tumor formation in the presence of inflam-mation and assess the ability of select agents to inhibit this *** admin-istration of DSS in drinking water results in the establishment of chronic colitisand the development of colorectal dysplasias and cancers with pathological fea-tures that resemble those of human colitis-associated *** incidenceand multiplicity of lesions observed varies depending on the mouse strain used(ie,Swiss Webster,C57bL/6J,CbA,ICR) and the dose (0.7%-5.0%) and schedule(1-15 cycles with or without a subsequent recovery period) of *** incidenceof neoplasia can be increased and its progression to invasive cancer acceleratedsignificantly by administering DSS in combination with a known colon carcinogen(azoxymethane (AOM),2-amino-3-methylimidazo[4,5-f]quinoline (IQ),2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)) or *** recent induction ofcolitis-associated neoplasia in genetically defined mouse strains has providednew insight into the role of specific genes (ie,adenomatous polyposis coli (Apc),p53,inducible nitric oxide synthase (iNOS),Msh2) in the development of colitis-associated *** data from chemopreventive intervention studiesdocument the efficacy of several agents in inhibiting DSS-induced neoplasiaand provide great promise that colitis-associated colorectal neoplasia is a pre-ventable disease.

关键词： colorectal colitis chemoprevention dextran sulfate sodium mouse models

基于势流理论和OpenFOAM的耦合模型对多向不规则波浪的模拟

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水科学进展 2016年第1期27卷 88-99页

作者：季新然柳淑学 bo T.PAULSEN harry b.bINGHAM 大连理工大学海岸和近海工程国家重点实验室辽宁大连116024 丹麦技术大学机械学院代尔夫特三角洲研究中心

基于势流理论的数值水池可以快速计算波浪的传播及其对建筑物的作用,但是势流理论是基于波浪的无黏性假设的,而在工程中,通常需要在固体边界及波浪破碎的区域考虑黏性效应。针对基于求解Navier-Stokes方程的黏性水池计算量较大、速度较... 详细信息

基于势流理论的数值水池可以快速计算波浪的传播及其对建筑物的作用,但是势流理论是基于波浪的无黏性假设的,而在工程中,通常需要在固体边界及波浪破碎的区域考虑黏性效应。针对基于求解Navier-Stokes方程的黏性水池计算量较大、速度较慢的缺点,采用耦合的方法模拟多向不规则波浪的传播,即在外域通过基于势流理论的数值水池产生多向不规则波浪,内域采用求解Navier-Stokes方程和流体体积法(VOF方法)对自由表面进行追踪,通过外域所提供的边界波浪,内域计算可以在较小区域进行计算,从而达到减少计算量、提高计算效率的目的。

关键词：势流理论 OpenFOAM 耦合多向不规则波浪

Applications of next-generation sequencing to the study of biological invasions

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Current Zoology 2015年第3期61卷 488-504页

作者： Marc RIUS Steve bOURNE harry Guy HORNSbY Mark A. CHAPMAN Ocean and Earth Science National Oceanography Centre Southampton University of Southampton SO 14 3ZH UK Centre for biological Sciences Life Sciences Building 85 University of Southampton Southampton SO 17 1B J UK

Through the widespread implementation of next-generation sequencing (NGS), analyses of the whole genome (the entire DNA content) and the whole transcriptome (the genes being expressed) are becoming commonplace. NGS enables the analysis of a vast amount of previously unattainable genetic information. Despite this potential, NGS has yet to be widely implemented in genetic studies of biological invasions. The study of the genomic causes and consequences of biological invasions allows a deeper understanding of the molecular mechanisms underpinning the invasion process. In this review, we present a brief introduction to NGS followed by a synthesis of current research in the genomics and transcriptomics of adaptation and colonization. We then highlight research opportunities in the field, including: (1) assembling genomes and transcriptomes of non-model organisms, (2) identifying genomic regions and candidate genes underlying evolutionary processes, and (3) studying the adaptive role of gene expression variation. In particular, because introduced species face a broad range of physiological and biotic challenges when colonizing novel and variable environments, transcriptomics will enable the study of gene regulatory pathways that may be responsible for acclimation or adaptation. To conclude, we identify a number of research approaches that will aid our future understanding of biological invasions.

关键词：生物入侵测序基因组分析应用转录组学基因表达 DNA含量信息分析