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simulation of thermal processes in metamaterial millimeter-wave to infrared converter for millimeter-wave imager

International Journal of Modeling, simulation, and scientific Computing 2014年第S1期5卷 120-128页

作者： peter s.Zagubisalo Andrey G.Paulish sergey A.Kuznetsov Novosibirsk Branch of the Institute of semiconductor Physics siberian Branch of Russian Academy of sciences 2/1 pr.Akademika LavrentyevaNovosibirsk 630090Russian Federation Novosibirsk state University 2 ul.PirogovaNovosibirsk 630090Russian Federation

The main characteristics of millimeter-wave(MM-wave)image detector were simulated by means of accurate numerical modeling of thermophysical processes in a metamaterial MM-to-IR *** converter represents a multilayer structure consisting of an ultra thin resonant metamaterial absorber and a perfect emissive *** absorber consists of a dielectric self-supporting film that is metallized from both sides.A micropattern is fabricated from one *** absorption of the MM waves induces the converter heating that yields enhancement of IR emission from the emissive *** emission is detected by IR *** this contribution an accurate numerical model for simulation of the thermal processes in the converter structure was created by using COMsOL Multiphysics *** simulation results are in a good agreement with experimental results that validates the *** simulation shows that the real-time operation is provided for the converter thickness less than 3µm and time response can be improved by decreasing of the converter *** energy conversion efficiency of MM waves into IR radiation is over 80%.The converter temperature increase is a linear function of a MM-wave radiation power within three orders of the dynamic *** blooming effect and ways of its reducing are also *** model allows us to choose the ways of converter structure optimization and improvement of image detector parameters.

关键词： Metamaterials subterahertz waves terahertz waves millimeter waves highimpedance surface ultra-thin absorber focal plane array detector bolometric detectors thermodynamic modeling optical readout system

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Variation in the plant-mediated methane transport and its importance for methane emission from intact wetland peat mesocosms

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Journal of Plant Ecology 2013年第4期6卷 298-304页

作者： Gurbir s.Bhullar peter J.Edwards Harry Olde Venterink Institute of Integrative Biology ETH ZurichUniversitätstrasse 168092 ZurichSwitzerland

Aims and Methods Vascular plants are known to influence the production,transport and oxidation of methane in wetland soils,but these processes are not well *** plants grown in intact peat cores,we compared the influence upon methane emissions of 20 forb and graminoid species from European *** measured plant-mediated transport of methane(conduit or chimney effect)using a novel agar-sealing technique that prevented methane exchange from the bare soil to the *** Findings the plant-mediated transport(chimney effect)represented between 30%and almost 100%of the total methane flux,with graminoids exhibiting greater internal transport than *** general,plants with less dense root tissues and a relatively larger root volume exhibited a larger chimney *** species(12 out of 20)signif-icantly reduced methane emissions compared to bare soil and only one species,succisa pratensis,increased *** suggest that characterising vegetation in terms of plant functional traits and plant processes offers an effective method for estimating methane emis-sions from ***,we found no correlation between the magnitude of the chimney effect and the overall influence of different plant species on methane *** introducing a useful tool to study plant-mediated transport,this work suggests that characterising vegetation in terms of functional traits could improve estimates of methane emissions from wetlands,which in turn could help in designing mitigation strategies.

关键词： functional group graminoid forb agar-sealing conduit gas transportreceived

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Clinical and dietary predictors of common carotid artery intima media thickness in a population with type 1 and type 2 diabetes: A cross-sectional study

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World Journal of Diabetes 2017年第1期8卷 18-27页

作者： Kristina s petersen Jennifer B Keogh peter J Meikle Manohar L Garg peter M Clifton school of Pharmacy and Medical sciences University of South Australia Baker IDI Heart and Diabetes Institute Nutraceuticals Research Group University of NewcastleCallaghan

AIM To determine the clinical and dietary predictors of common carotid artery intima media thickness(CCA IMT) in a cohort of subjects with type 1 and type 2 diabetes. METHODs Participants with type 1(n = 23) and type 2 diabetes(n = 127) had mean and mean maximum CCA IMT measured using B mode ultrasound. Dietary intake was measured using a food frequency questionnaire. Clinical and dietary predictors of mean and mean maximum CCA IMT were determined using linear regression analysis adjusted for potential confounders. REsULTs The main predictors of mean and mean maximum CCA IMT were age and weight. After multivariate adjustment there were no dietary predictors of CCA IMT. However,in subjects that were not prescribed a lipid lowering medication alcohol consumption was positively associated with CCA IMT after multivariate adjustment. No difference existed in CCA IMT between subjects with type 1 or type 2 diabetes once age was adjusted for. CONCLUsION CCA IMT was predominantly predicted by age and weight in these subjects with diabetes. The finding that CCA IMT was not different between people with type 1 and type 2 diabetes warrants further investigation in a larger cohort.

关键词： Diabetes Carotid intima media thickness Arterial structure Diet Lipidomics Carotenoids

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seasonal changes in group size and composition of Arabian sand gazelle Gazella subgutturosa marica Thomas, 1897 during a period of drought in central western saudi Arabia

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Current Zoology 2011年第1期57卷 36-42页

作者： peter Low CUNNINGHAM King Khalid Wildlife Research Centre Thumamah E O. Box 61681 Riyadh Kingdom of Saudi Arabia Zoological society of London Conservation Programmes Regent's Park London NW1 4RY United Kingdom

Group size variations of the Arabian sand gazelle Gazella subgutturosa marica were studied during a period of drought at the Mahazat as-sayd Protected Area in central western saudi Arabia. significant differences in median group sizes were observed between all seasons except summer. single animals were observed mainly during summer while group sizes ex- ceeding 10 individuals were observed mainly during winter. solitary male and female groups were typically observed during winter and mixed groups mainly during the autumn rutting period. Most mixed groups were two to four times larger during winter than summer. The adult sex ratio （male： female） for all seasons combined was in parity and highest during autumn （1：1.23）, probably as a result of prolonged drought conditions. The variability in group structure related to environmental conditions may be one factor permitting G. s. marica to adapt to hyper-arid habitats and climatic regimes in central western saudi Arabia. The value of continuous monitoring of the gazelle population is emphasised for this drought prone region

关键词： Group variations seasonality sex ratio Desert ungulate Mahazat as-sayd Protected Area

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Experimental investigation on slip conditions during thread rolling with flat dies

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Friction 2024年第1期12卷 136-143页

作者： stefan VOLZ peter GROCHE Institute for Production Engineering and Forming Machines Technical University DarmstadtOtto-Berndt Straße 2Darmstadt 64287Germany

The process design of flat die rolling operations can be a tedious and costly process due to the challenges posed by small process *** this work,an effort is made to closely investigate and understand the process limits caused by excessive slippage of the *** measurements are carried out to capture the characteristics of excessive slippage and the influence of the stroke rate and the tribological system on this process *** differences in slippage were observed,depending on the tribological *** systems with polymer based lubricants showed excessive slippage at low stroke rates,systems using oil or no lubricant endured higher stroke rates before process limits were *** optical measurements revealed three major forms of slippage:successful rolling without slippage,failure due to excessive slippage at process start,and failure due to excessive slippage at around one workpiece rotation.

关键词： rolling incremental forming thread rolling slippage profile rolling

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“Towards Re-Inventing Psychohistory”:Predicting the Popularity of Tomorrow’s News from Yesterday’s Twitter and News Feeds

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Journal of systems science and systems Engineering 2021年第1期30卷 85-104页

作者： Jiachen sun peter Gloor MIT Center for Collective Intelligence 245 First StreetCambridgeMA02142USA school of Electronics and Information Technology Sun Yat-Sen UniversityGuangzhou510275China

Rapid advances in machine learning combined with wide availability of online social media have created considerable research activity in predicting what might be the news of tomorrow based on an analysis of the *** this work,we present a deep learning forecasting framework which is capable to predict tomorrow’s news topics on Twitter and news feeds based on yesterday’s content and topic-interaction *** proposed framework starts by generating topics from words using word embeddings and K-means *** temporal topic-networks are constructed where two topics are linked if the same user has worked on both *** and dynamic metrics calculated from networks along with content features and past activity,are used as input of a long short-term memory(LsTM)model,which predicts the number of mentions of a specific topic on the subsequent *** dependencies among topics,our experiments on two Twitter datasets and the HuffPost news dataset demonstrate that selecting a topic’s historical local neighbors in the topic-network as extra features greatly improves the prediction accuracy and outperforms existing baselines.

关键词： Topic’s popularity trend forecasting social media

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Hypervelocity Impacts and Exposed Lithospheric Mantle: A Way to Recognize Large Terrestrial Impact Basins?

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Journal of Earth science 2019年第3期30卷 451-459页

作者： peter Olds Chemistry Faculty College of Alameda

On the Moon and Mars olivine of probable mantle origin is detected at rims of large Late Heavy Bombardment(LHB) age impact basins for which excavation depth estimates exceed crustal thickness estimates. But lunar Crisium size impact basins are not recognized on Earth nor expected in the Phanerozoic from conventional interpretations of crater size frequency distributions. In this study several large circular to elliptical basin structures on Earth, for which hypothesized impact excavation depth would greatly exceed crustal thickness, are examined for the presence of exposed lithospheric mantle, expressed as ophiolite, at the rims. Three Phanerozoic impact basins, modified by plate tectonics and tentatively correlated with "ophiolite obduction" plus global extinction events, are proposed here. These tentatively suggested Phanerozoic impact basins are:(1) Yucatan Basin/Puerto Rico Trench with a Greater Antilles ophiolite rim. Cretaceous-Paleogene Boundary global extinction may correlate with Maastrichtian ophiolite obduction in southeast Cuba.(2) Loyalty Basin with a New Caledonia ophiolite plus d’Entrecasteaux Ridge rim. Late Eocene global extinction may correlate with obduction of the New Caledonia Peridotite Nappe.(3) sulu sea Basin with a Palawan, sabah etc. ophiolite rim. The Middle Miocene Disruption Event may correlate with ophiolite obduction plus ophiolitic mélange emplacement in sabah and in Palawan. These originally circular to elliptical belts of exposed lithospheric mantle may serve as strain markers for relative plate motions in the vicinity of plate boundaries during post-impact geologic times. It is further speculated that plate boundaries may be initiated and/or modified by such impacts.

关键词： olivine mantle impact basin ophiolite obduction mass extinction

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Genetic climatic regionalization of the Balkan Peninsula using cluster analysis

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Journal of Geographical sciences 2017年第1期27卷 43-61页

作者： peter NOJAROV National Institute of Geophysics Geodesy and Geography Bulgarian Academy of Sciences Akad. G. BonchevStr. BI.3 Room 327 1113 Sofia Bulgaria

sea Level Pressure（sLP） data for the period 1950–2012 at 61 stations located in or around the Balkan Peninsula was used. The main concept is that intra-annual course of sLP represents the best different air masses that are situated over the Balkan Peninsula during the year. The method for differentiation of climatic zones is cluster analysis. A hierarchical clustering technique–average linkage between groups with Pearson correlation for measurement of intervals was employed in the research. The climate of the Balkan Peninsula is transitional between oceanic and continental and also between subtropical and temperate climates. several major changes in atmospheric circulation over the Balkan Peninsula have happened over the period 1950–2012. There is a serious increase of the influence of the Azores High in the period January–Marchwhich leads to an increase of sLP and enhances oceanic influence. There is an increase of the influence of the north-west extension of the monsoonal low in the period June–september. This leads to more continental climatebut also to more tropical air masses over the Balkan Peninsula. Accordinglythe extent of subtropical climate widens in northern direction. There is an increase of the influence of the siberian High in the period October–December. This influence covers central and eastern part of the peninsula in October and Novemberand it reaches western parts in December. Thusthe climate becomes more continental.

关键词： genetic classification regionalization Balkan Peninsula cluster analysis sea Level Pressure circulation indices

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Nonlocal Nonlinear Advection-Diffusion Equations

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Chinese Annals of Mathematics,series B 2017年第1期38卷 281-292页

作者： peter CONsTANTIN Department of Mathematics Princeton UniversityPrincetonNJ 08544USA.

The author reviews some results about nonlocal advection-diffusion equations based on lower bounds for the fractional Laplacian.

关键词： Nonlocal Advection Diffusion Fractional Laplacian

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Generic principles of crack-healing ceramics

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Journal of Advanced Ceramics 2012年第4期1卷 249-267页

作者： peter GREIL Department of Materials science(Glass and Ceramics) University of Erlangen-NuernbergMartensstr.5Erlangen 91058Germany

Ceramic materials able to heal manufacture or damage induced microstructure defects might trigger a change in paradigm for design and application of load bearing *** work reviews thermodynamic and kinetic aspects governing the regeneration of solid contact able to transfer stress between disrupted crack surfaces in *** crack healing processes include perturbation of crack-like pores followed by sintering of isolated pores,as well as reaction with an environmental atmosphere and filling of the crack space with an oxidation *** thermally activated solid state reactions require elevated temperatures which may exceed 1000℃,processes able to trigger crack healing at lower temperatures are of particular interest for transferring into engineering *** principles of microstructure modifications able to facilitate crack repair at lower temperatures will be considered:(i)acceleration of material transport by grain boundary decoration and grain size reduction,and(ii)reduction of thermal activation barrier by repair filler *** demonstrating crack healing capability include oxidation reaction of low energy bonded intercalation metal from nano-laminate MAX phases and catalyzed surface nitridation of polymer derived ceramics containing repair fillers.

关键词： crack healing microstructure modifications oxidation healing MAX phases preceramic polymers

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