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Structural analysis of rubble-pile asteroids applied to collisional evolution

Astrodynamics 2017年第1期1卷 57-69页

作者： Yang Yu derek CRichardson patrick Michel School of Aeronautic Science and Technology Beihang UniversityBeijing 100191China department of Astronomy University of MarylandCollege Park MD 20740-2421USA Observatoire de la Cote d'Azur UMR 7293 Lagrange/CNRS06304 Nice Cedex 4France

Solar system small bodies come in a wide variety of shapes and sizes,which are achieved following very individual evolutional paths through billions of ***,some common mechanisms can still be found during these processes,e.g.,rubble-pile asteroids tend towards fluid equilibrium as they are reshaped by external *** paper focuses on the reshaping process of rubble-pile asteroids driven by meteorite impacts.A mesoscale cluster of solid spheres is employed as the principal model for a rubble-pile asteroid,for which little is actually known about their interior *** take this simple model as a rough guide to the qualitative aspects of the reshaping processes,and it can reveal,to some degree,the inner workings of rubble-pile *** our study,numerous possible equilibrium configurations are obtained via Monte Carlo simulation,and the structural stability of these configurations is determined via eigen analysis of the geometric *** eigen decomposition reveals a connection between the cluster’s reactions and the types of external *** simulations are performed to verify the analytical *** gravitational N-body code pkdgrav is used to mimic the responses of the cluster under intermittent non-dispersive *** statistically confirm that the stability index I S,the total gravitational potential P G,and the volume of inertia ellipsoid V E show consistent tendency of variation.A common regime is found in which the clusters tend towards crystallization under intermittent impacts,i.e.,only the configurations with high structural stability survive under the external *** results suggest the trivial non-disruptive impacts might play an important role in the rearrangement of the constituent blocks,which may strengthen these rubble piles and help to build a robust structure under impacts of similar *** final part of this study consists of systematic simulations over two parameters

关键词： asteroids interior structure geological processes N-body simulations gravitational aggregates meteorite impacts

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Hastily formed knowledge networks and distributed situation awareness for collaborative robotics

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Autonomous Intelligent Systems 2021年第1期1卷 244-272页

作者： patrick doherty Cyrille Berger Piotr Rudol Mariusz Wzorek department of Computer and Information Science Linköping UniversityLinköpingSweden School of Intelligent Systems and Engineering Jinan University(Zhuhai Campus)ZhuhaiChina

In the context of collaborative robotics,distributed situation awareness is essential for supporting collective intelligence in teams of robots and human agents where it can be used for both individual and collective decision *** is particularly important in applications pertaining to emergency rescue and crisis *** operational missions,data and knowledge are gathered incrementally and in different ways by heterogeneous robots and *** describe this as the creation of Hastily Formed Knowledge Networks(HFKNs).The focus of this paper is the specification and prototyping of a general distributed system architecture that supports the creation of HFKNs by teams of robots and *** information collected ranges from low-level sensor data to high-level semantic knowledge,the latter represented in part as RdF *** framework includes a synchronization protocol and associated algorithms that allow for the automatic distribution and sharing of data and knowledge between *** is done through the distributed synchronization of RdF Graphs shared between ***-level semantic queries specified in SPARQL can be used by robots and humans alike to acquire both knowledge and data content from team *** system is empirically validated and complexity results of the proposed algorithms are ***,a field robotics case study is described,where a 3d mapping mission has been executed using several UAVs in a collaborative emergency rescue scenario while using the full HFKN Framework.

关键词： Multi-robot collaboration Unmanned aerial vehicles distributed knowledge representation distributed situation awareness Semantic web technology Knowledge synchronization Multi-agent human/robot interaction

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Evidence of dual Scale Porous Mechanisms during Fluid Migration in Hardwood Species (Ⅱ) A dual Scale Computational Model to describe the Experimental Results

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Chinese Journal of Chemical Engineering 2004年第6期12卷 783-791页

作者： patrick PERR LERMAB-UMR INRA/ENGREF/UHP 1093 ENGREF-INRA-14 rue Girardet 54042 Nancy Cedex France

The second part of this paper is devoted to the computational modelling of transient water migration in hardwood. during re-saturation, the moisture content, measured during the process by using X-ray attenuation (see part 1 of this paper), increases quickly very close to the cavity, but requires a very long time for the remaining part of the sample to absorb the moisture in wetting. For this configuration and this material, the macroscopic approach fails. Consequently, a dual-porosity approach is proposed. The computational domain uses a 2-d axisymmetric configuration for which the axial coordinate represents the macroscopic longitudinal direction of the sample whereas the radial coordinate allows the slow migration from each active vessel towards the fibre zone to be considered. The latter is a microscopic space variable. The moisture content field evolution depicts clearly the dual scale mechanisms:a very fast longitudinal migration in the vessel followed by a slow migration from the vessel towards the fibre *** macroscopic moisture content field resulting from this dual scale mechanism is in quite good agreement with the experimental data.

关键词： fluid migration dual-porosity computational model hardwood vessel fibre

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Guest Editorial for Special Issue on Time Series Classification

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IEEE/CAA Journal of Automatica Sinica 2019年第6期6卷 1291-1292页

作者： Houshang darabi Georgiana Ifrim patrick Schafer diego Furtado Silva department of Mechanical and Industrial Engineering University of Illinois at Chicago(UIC) University of Bucharest Romania University of Berlin Sciences(ICMC) University of Sao Paulo

TIME series classification research and applications have recently received a lot of *** the rapid advancement of technological devices,time series data are being collected by a wide variety of devices,resulting in a wide range of research and *** fields of studies,ranging from healthcare to weather readings,require time series *** and action recognition using time series data from fitness trackers are commonly being ***,a new generation of algorithms and techniques are being used to classify time series data that are extensively available to the research *** example,recently deep learning techniques that utilize convolutions and recurrent neural networks are being used to classify epileptic seizures from EEG recordings made available at the University of California-Irvine data repository.

关键词： classify utilize recording

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Plasticity in the antipredator behavior of the orange-footed sea cucumber under shifting hydrodynamic forces

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Current Zoology 2019年第6期65卷 685-695页

作者： Nicholas A.W.BROWN david R.WILSON patrick GAGNON department of Ocean Sciences Memorial University of NewfoundlandSt.John'sNewfoundlandA1C 5S7Canada department of Psychology Memorial University of NewfoundlandSt.John'sNewfoundlandA1B 3X9Canada

Marine invertebrates that move too slowly to evade unfavorable environmental change may instead exhibit phenotypic plasticity,allowing them to adjust to varying *** orange-footed sea cucumber Cucumaria frondosa is a slow-moving suspension feeder that is preyed on by the purple sunstar Solaster *** sea cucumber's antipredator behavior involves changing shape and detaching from the substratum,which might increase its probability of being displaced by water motion into an unsuitable *** hypothesized that sea cucumbers'antipredator responses would be diminished under stronger hydrodynamic forces,and that behavioral strategies would be flexible so that individuals could adjust to frequent changes in water *** a natural orange-footed sea cucumber habitat,individuals lived along a pronounced hydrodynamic gradient,allowing us to measure antipredator behavior under different water flow *** placed purple sunstars in physical contact with sea cucumbers living at various points along the gradient to elicit antipredator *** then repeated this procedure in a laboratory mesocosm that generated weak and strong hydrodynamic forces similar to those observed at the field *** in the mesocosm experiment were tested in both wave conditions to determine if their antipredator behavior would change in response to sudden environmental change,as would be experienced under deteriorating sea *** responses did not covary with hydrodynamic forces in the ***,antipredator responses in the mesocosm experiment increased when individuals were transplanted from strong to weak forces and decreased when transplanted from weak to strong ***,our results indicate environmentally induced plasticity in the antipredator behavior of the orange-footed sea cucumber.

关键词： behavioral plasticity benthic invertebrate predator-prey interaction reciprocal transplant experiment Solaster endeca.wave environment

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Laboratory study on the formation of Al2O3 inclusions at the on-set of deoxidation and during reoxidation

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Frontiers of Materials Science 2011年第1期5卷 69-76页

作者： Marie-Aline VAN ENdE Muxing GUO Bart BLANPAIN patrick WOLLANTS department of Metallurgy and Materials Engineering Katholieke Universiteit Leuven Kasteelpark Arenberg 44- bus 2450 BE-3001 Leuven Belgium Unite d＇lngeniede des Materiaux et des Procedes Universite Catholique de Louvain Place Sainte Barbe 2 B-1348 Louvain-la-Neuve Belgium

The formation of Al2O3 inclusions in liquid iron has been investigated in a resistance heated tube furnace to obtain deoxidation and reoxidation related data. The formation of inclusions during the early stages of deoxidation was simulated by bringing a piece of AI in contact for a short time with liquid Fe containing different dissolved oxygen levels. Reoxidation was studied by exposing AI containing Fe melts to a CO/CO2 atmosphere, Through modeling, an estimate of the local and time-dependent growth conditions for the inclusions can be made and linked to the inclusion characteristics.

关键词： steel cleanliness Al2O3 inclusions deoxidation reoxidation morphology

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Understanding temporal stability:a long-term analysis of USdA ARS watersheds

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International Journal of digital Earth 2021年第10期14卷 1243-1254页

作者： Evan J.Coopersmith Michael H.Cosh patrick J.Starks david d.Bosch Chandra Holifield Collins Mark Seyfried Stan Livingston John Prueger Soil Insight LLCWashington D.C.USA USdA-Agricultural Research Service Beltsville Agricultural Research CenterHydrology and Remote Sensing LaboratoryBeltsvilleUSA USdA-Agricultural Research Service-Grazinglands Research Laboratory El RenoUSA USdA-Agricultural Research Service-Southeast Watershed Research Laboratory TiftonUSA USdA-Agricultural Research Service-Southwest Watershed Research Center TucsonUSA USdA-Agricultural Research Service-Northwest Watershed Research Laboratory BoiseUSA USdAAgricultural Research Service-National Soil Erosion Research Laboratory West LafayetteUSA USdA-Agricultural Research Service-National Laboratory for Agriculture and Environment AmesUSA

The *** of Agriculture’s Agricultural Research Service(USdAARS)maintains seven in situ soil moisture networks throughout the continental United States,some since *** networks are crucial for understanding the spatial and temporal extent of droughts in their historical context,parameterization of hydrologic models,and local agricultural decision ***,the estimates from these networks are dependent upon their ability to provide reliable soil moisture information at a large *** is also not known how many network stations are sufficient to monitor watershed scale ***,the objectives of this research were to:(1)determine how temporally stable these networks are,including the relationships between various sensors on a year-to-year and seasonal basis,and(2)attempt to determine how many sensors are required,within a network,to approximate the full network *** data from seven in situ,it is concluded that approximately 12 soil moisture sensors are sufficient in most environments,presuming their locations are distributed to capture the hydrologic heterogeneity of the *** is possible to install a temporary network containing a suitable number of sensors for an appropriate length of time,glean stable relationships between locations,and retain these insights moving forward with fewer sensor resources.

关键词： Soil moisture temporal stability in situ networks

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Electrocatalytic hydrogen peroxide formation on mesoporous non-metal nitrogen-doped carbon catalyst

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Journal of Energy Chemistry 2016年第2期25卷 249-255页

作者： Frédéric Hasché Mehtap Oezaslan Peter Strasser Tim-patrick Fellinger Technische Universitat Berlin Department of Chemistry10623 BerlinGermany Max Planck Institut fur Kolloid-und Grenzfliichenforschung Department of Colloids14424 PoadamGermany Carl von Ossietzky University of Oldenburg Department of ChemistryElectrocatalysis26111 OldenburgGermany

direct electrochemical formation of hydrogen peroxide（H2O2） from pure O2 and H2on cheap metal-free earth abundant catalysts has emerged as the highest atom-efficient and environmentally friendly reaction pathway and is therefore of great interest from an academic and industrial point of view. Very recently,novel metal-free mesoporous nitrogen-doped carbon catalysts have attracted large attention due to the unique reactivity and selectivity for the electrochemical hydrogen peroxide formation [1–3]. In this work,we provide deeper insights into the electrocatalytic activity, selectivity and durability of novel metal-free mesoporous nitrogen-doped carbon catalyst for the peroxide formation with a particular emphasis on the influence of experimental reaction parameters such as p H value and electrode potential for three different electrolytes. We used two independent approaches for the investigation of electrochemical hydrogen peroxide formation, namely rotating ring-disk electrode（RRdE） technique and photometric UV–VIS technique. Our electrochemical and photometric results clearly revealed a considerable peroxide formation activity as well as high catalyst durability for the metal-free nitrogen-doped carbon catalyst material in both acidic as well as neutral medium at the same electrode potential under ambient temperature and pressure. In addition, the obtained electrochemical reactivity and selectivity indicate that the mechanisms for the electrochemical formation and decomposition of peroxide are strongly dependent on the p H value and electrode potential.

关键词： Electrochemical hydrogen peroxide formation Selectivity Mesoporous nitrogen-doped carbon Green synthesis Electrocatalysis Metal-free catalysis

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Comparisons between numerical calculations and measurements in vaned diffuser of SHF impeller

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排灌机械工程学报 2013年第12期31卷 1013-1020页

作者： Annie-Claude Bayeul-Lainé patrick dupont Giovanna Cavazzini patrick Cherdieu Antoine dazin Gérard Bois Olivier Roussette Laboratoire de Mécanique de Lille(UMR CNRS 8107) Arts et Métiers ParisTech Laboratoire de Mécanique de Lille(UMR CNRS 8107) Ecole Centrale de LilleVilleneuve D'Ascq Cedex 59651France department of Industrial Engineering University of Padova

The paper presents analysis of the performance and the internal flow behaviour in the vaned diffuser of a radial flow pump using PIV(particle image velocimetry)and pressure probe *** measurements have already been performed at middle height inside one diffuser channel passage for a given speed of rotation and various mass flow *** results have been already presented in several previous *** experiments have been performed using a three-hole pressure probe traverses from hub to shroud diffuser width at different radial locations between the two diffuser geometrical *** simulations are also realized with the commercial codes Star CCM+7.02.011 and *** rotor and fully unsteady calculations of the whole pump have been *** between numerical results,previous experimental PIV results and new probe traverses one's are presented and discussed for one mass flow *** this respect,a first attempt to take into account fluid leakages between the rotating and fixed part of the pump has been checked since it may affects the real flow structure inside the diffuser.

关键词： vaned diffuser radial flow pump unsteady flow numerical calculations particle image velocimetry(PIV) three-hole probe

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Effect of age on aortic atherosclerosis

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Journal of Geriatric Cardiology 2013年第2期10卷 135-140页

作者： Michael A. Chen Miwa Kawakubo patrick M. Colletti dongxiang Xu Laurie LaBree dustin Robert detrano Stanley P Azen Nathan d. Wong Xue-Qiao Zhao department of Medicine Division of Cardiology Harborview Medical Center/University of Washington 325 9th Avenue Box 359748 Seattle WA 98104 USA department of Preventive Medicine Division of Biostatistics Keck School of Medicine of the University of Southern California 2001 N Soto Street SSB 201A M/C 9234 Los Angeles CA 90089-9237 USA department of Radiology Keck School of Medicine of the University of Southern California1 1500 San Pablo Street Second Floor Imaging Los Angeles CA 90033 USA department of Radiology University of Washington School of Medicine Box 357115 1959 Pacific Street RR-215 Seattle WA 98195-7117 USA department of Radiological Sciences University of California Irvine School of Medicine 101 the City Drive South Route 140 Orange CA 92868 USA department of Medicine UC Irvine School of Medicine 333 City Blvd. West Suite 400 Orange CA 92868-3298 USA

Objective To examine the association of atherosclerosis burden in the survivors of an asymptomatic elderly cohort study and its relationship to other coronary risk factors (specifically, age) by evaluating aortic atherosclerotic wall burden by magnetic resonance imaging (MRI). Methods A total of 312 participants in an ongoing observational cohort study underwent cardiac and descending thoracic aorta imaging by MRI. Maximum wall thickness was measured and the mean wall thickness ***/outer wall ratio was used as a normalized wall index (NWI) adjusted for artery size difference among participants. Percent wall volume (PWV) was calculated as NWI ×*** In this asymptomatic cohort (mean age: 76 years), the mean (Sd) aortic wall area andwall thicknesswere 222 ±45 mm2 and 2.7 ±0.4 mm, respectively. Maximum wall thickness was 3.4 ±0.6 mm, and PWV was 32% ±4%. Women appeared to have smaller wall area,but after correcting for their smaller artery size, had significantly higher PWV than men (P = 0.03). Older age was associatedwith larger wall area (P = 0.04 for trend) with similar PWVs. However, there were no statistically significant associations between standard risk factors,Framingham global risk, or metabolic syndrome status, therapy for cholesterol or hypertension, coronary or aortic calcium score, and the aortic wall burden. Aortic calcificationwas associated with coronary calcification. Conclusions Asymptomatic elderly in this cohort had a greater descending thoracic aortic wall volume that correlated with age, andwomen had a significantly increased PWV compared to men. In these survivors, the atherosclerotic aortic wall burden was not significantly associated with traditional risk factors or with coronary or aortic calcium scores or coronary calcium progression. Results suggest that age, or as yet unidentified risk factor(s), may be responsible for the increase in atherosclerosis.

关键词： Aging Aortic atherosclerosis Atherosclerotic risk factors Magnetic resonance imaging

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