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An Event Horizon Imager(EHI) mission Concept Utilizing medium Earth Orbit Sub-mm Interferometry

空间科学学报 2021年第2期41卷 211-233页

作者： KUDRIASHOV V mARTIN-NEIRA m ROELOFS F FALCKE H BRINKERINK C BARYSHEV A HOGERHEIJDE m YOUNG A POURSHAGHAGHI H KLEIN-WOLT m mOSCIBRODZKA m DAVELAAR J BARAT I DUESmANN B VALENTA V PERDIGUES ARmENGOL J m DE WILDE D mARTIN IGLESIAS P ALAGHA N VAN DER VORST m Department of Astrophysics/ImAPP Radboud University NijmegenP.O.Box 90106500 GL Nijmegenthe Netherlands ESTEC/ESA Keplerlaan 12201 A2 Noordurigkthe Netherlands mar Planck Institute for Radio Astrorny Auf dem Higel 69D-53121 Bon(Endenich)Germany University of Groningen Landleven 129747 AD Groningenthe Netherlands Leiden Observatory Leiden UniversityPO Box 95132300 RALeidenthe Netherlands Anton Pannekoek Institute for Astronomy University of AmsterdamScience Park 9041098 XHAmsterdamthe Netherlands Center for Computational Astrophysics Flatiron Institute162 Fifth AvenueNew YorkNY 10010USA

Submillimeter interferometry has the potential to image supermassive black holes on event horizon scales,providing tests of the theory of general relativity and increasing our understanding of black hole accretion *** Event Horizon Telescope(EHT) performs these observations from the ground,and its main imaging targets are Sagittarius A~* in the Galactic Center and the black hole at the center of the m87 ***,the EHT is fundamentally limited in its performance by atmospheric effects and sparse terrestrial(u,v)-coverage(Fourier sampling of the image).The scientific interest in quantitative studies of the horizon size and shape of these black holes has motivated studies into using space interferometry which is free of these *** resolution considerations and interstellar scattering effects push the desired observing frequency to bands above 500 *** paper presents the requirements for meeting these science goals,describes the concept of interferometry from Polar or Equatorial medium Earth Orbits(PECmEO) which we dub the Event Horizon Imager(EHI),and utilizes suitable space technology *** this concept,two or three satellites orbit at slightly different orbital radii,resulting in a dense and uniform spiral-shaped(u,v)-coverage over *** local oscillator signals are shared via an inter-satellite link,and the data streams are correlated on-board before final processing on the ***-satellite metrology and satellite positioning are extensively employed to facilitate the knowledge of the instrument position vector,and its time *** European space heritage usable for both the front ends and the antenna technology of such an instrument is *** and future sensors for the required inter-satellite metrology are *** performance estimates and simulation results are given.

关键词： Instrumentation Space VLBI Radio Telescopes

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Energy transport for ion acoustic waves in a spin polarized quantum plasma

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Communications in Theoretical Physics 2020年第1期72卷 124-129页

作者： m Ayub Z Iqbal H A Shah G murtaza Salam Chair Department of PhysicsG.C.UniversityKatchery RoadLahore 54000Pakistan Department of Physics G.C.UniversityKatchery RoadLahore 54000Pakistan Department of Physics Mirpur University of Science and TechnologyMirpur-10250(AJK)Pakistan

The separate spin evolution quantum hydrodynamics(SSE-QHD)model is used to investigate the energy behavior for ion acoustic waves in degenerate quantum *** results show that the energy flow speed decreases with spin polarization *** is also shown that it decreases with the increasing rate up to a certain range of wave number and then it goes to zero *** is observed that Bohm potential suppresses the energy flow *** is also noticed that the energy flow speed deviates from the group velocity even in the absence of Bohm potential ***,the contribution of of Bohm poential effect in spin polarized plasma reduces the extent of deviation.

关键词： spin polarization quantum plasma ion acoustic wave energy flow speed

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Impacts of longterm conservation measures on ecosystem services in Northwest Ethiopia

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International Soil and Water Conservation Research 2020年第1期8卷 47-55页

作者： Woubet G.Alemu Assefa m.melesse Department of Earth and Environment Florida International UniversityMiamiFL33199USA

A Soil Conservation Research Program(SCRP)has been on-going in Anjeni Watershed,Amhara Region,Ethiopia since the 1980s,focussing particularly on soil-based,graded fanya juu *** study was carried out to examine the long-term impacts of these soil and water conservation measures in improving ecosystem services.A comparative analysis was made with a non-treated 100 ha adjacent watershed(Zikrie).The Revised Universal Soil Loss Equation(RUSLE)was used in a geographic infor-mation system(GIS)to quantify soil *** soil samples were taken 30 cm deep soil pits in the loss and deposition zones in the terraced Anjeni and topo-sequential soil samples on both *** analysis was carried out at the National Soil Testing Laboratory(NSTL)of *** texture,pH and OC were analyzed for the 91 soil samples.A GIS analysis of the RUSLE factors was made on a 5 m grid cell *** mean annual soil loss rate in Anjeni was estimated to be 37 t ha^-1 yr^-1,while that of the adjacent non-conserved Zikrie was 45 t ha^-1 yr^-*** total estimated soil loss in Anjeni watershed was 4214 t yr^-*** valleys in the Anjeni watershed had the maximum mean annual esti-mated soil loss hazard(86 t ha^-1 yr^-1).Cultivated land had medium mean annual estimated soil loss(44 t ha^-1 yr^-1)due to the soil conservation *** the soil-based graded fanya juu terraces with biological soil conservation measures is important for the stability of the ecosystem.

关键词： Soil and water conservation Soil loss RUSLE GIS Anjeni

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Linear matrix inequality approach for synchronization control of fuzzy cellular neural networks with mixed time delays

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Chinese Physics B 2012年第4期21卷 586-596页

作者： P.Balasubramaniam m.Kalpana R.Rakkiyappan Department of mathematics Gandhigram Rural Institute-Deemed UniversityGandhigram-624302TamilnaduIndia Department of mathematics Bharathiar UniversityCoimbatore-641046TamilnaduIndia

Fuzzy cellular neural networks （FCNNs） are special kinds of cellular neural networks （CNNs）. Each cell in an FCNN contains fuzzy operating abilities. The entire network is governed by cellular computing laws. The design of FCNNs is based on fuzzy local rules. In this paper, a linear matrix inequality （LmI） approach for synchronization control of FCNNs with mixed delays is investigated. mixed delays include discrete time-varying delays and unbounded distributed delays. A dynamic control scheme is proposed to achieve the synchronization between a drive network and a response network. By constructing the Lyapunov-Krasovskii functional which contains a triple-integral term and the free-weighting matrices method an improved delay-dependent stability criterion is derived in terms of LmIs. The controller can be easily obtained by solving the derived LmIs. A numerical example and its simulations are presented to illustrate the effectiveness of the proposed method.

关键词： asymptotic stability chaos fuzzy cellular neural networks linear matrix inequalities synchronization

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Three-dimensional mixed convection flow with variable thermal conductivity and frictional heating

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Communications in Theoretical Physics 2020年第3期72卷 14-20页

作者： m Qasim N Riaz Dianchen Lu S Shafie Department of mathematics Faculty of ScienceJiangsu UniversityZhenjiang 212013China Department of mathematics COMSATS University Islamabad(CUI)455000Park RoadTarlai KalanIslamabad.Pakistan Department of mathematical Sciences Faculty of ScienceUniversiti Teknologi Malaysia81310 UTM Johor BahruJohor 81310Malaysia

In this article,three-dimensional mixed convection flow over an exponentially stretching sheet is *** equation is modelled in the presence of viscous dissipation and variable thermal *** of the sheet is varying exponentially and is chosen in a form that facilitates the similarity transformations to obtain self-similar *** nonlinear ordinary differential equations are solved numerically employing the Runge-Kutta shooting *** order to check the accuracy of the method,these equations are also solved using bvp4c built-in routine in *** solutions are in excellent *** effects of physical parameters on the dimensionless velocity field and temperature are demonstrated through various *** novelty of this analysis is the self-similar solution of the threedimensional boundary layer flow in the presence of mixed convection,viscous dissipation and variable thermal conductivity.

关键词： self-similar equations viscous dissipation mixed convection variable thermal conductivity shooting technique bvp4c matlab

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Effect of electrolyte temperature on the nano-carbonitride layer fabricated by surface nanocrystallization and plasma treatment on a γ-TiAl alloy

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Rare metals 2009年第5期28卷 454-459页

作者： m. Aliofkhazraei A. Sabour Rouhaghdam H. Hassannejad Department of materials Engineering Faculty of Engineering Tarbiat Modares University

The distribution of nano-carbonitrides produced by the treatments of surface nanocrystallization and plasma electrolytic carbonitriding on a γ-TiAl was investigated by means of figure analysis. The skewness and kurtosis of Gaussian shape distribution curves were studied and the effect of electrolyte temperature was determined. The usage of lower temperatures of the electrolyte is more suitable for achieving lower sizes of complex nano-carbonitrides. The surface roughness of treated samples was measured and it was observed that there is an optimum level of electrolyte temperature for surface roughness increase （difference between two measured data）.

关键词： carbonitride electrolyte temperature nanostructures plasma electrolytic deposition roughness γ-TiAl

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Larger floods reduce soil CO_(2)efflux during the post-flooding phase in seasonally flooded forests of Western Amazonia

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Pedosphere 2021年第2期31卷 342-352页

作者： Emma m.DOCHERTY Andrew D.THOmAS Department of Geography and Earth Sciences Aberystwyth UniversityAberystwyth SY233DB(UK) School of Geography University of LeedsLeeds LS29JT(UK)

Seasonally flooded várzea forests of Western Amazonia are one of the most productive and biodiverse wetland forests in the ***,data on their soil CO_(2)emissions,soil organic matter decomposition rates,and soil C stocks are *** is a concern because hydrological changes are predicted to lead to increases in the height,extent,and duration of seasonal floods,which are likely to have a significant effect on soil C stocks and ***,with no empirical data,the impact of altered flood regimes on várzea soil C cycles remains *** study quantified the effects of maximum annual flood height and soil moisture on soil CO_(2)efflux rate(R_(s))and soil organic matter decomposition rate(k)in the várzea forests of Pacaya Samiria National Reserve,*** study was conducted between may and August *** results showed that R_(s)(10.6–182.7 mg C m^(-2)h^(-1))and k(0.016–0.078)varied between and within sites,and were considerably lower than the values reported for other tropical *** addition,R_(s)was negatively affected by flood height(Pmoisture(Pmentioned *** moisture was the dominant factor influencing R_(s),and it was significantly affected by maximum flood height,even after the floods had subsided(Pmain unchanged but with decomposition processes becoming more anaerobic.

关键词： C cycle climate change greenhouse gas soil CO_(2)emissions soil moisture soil organic matter decomposition rate tropical forest

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Al–TiO_2–Gr powder metallurgy hybrid composites with cold upset forging

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Rare metals 2014年第6期33卷 686-696页

作者： m.Ravichandran A.Naveen Sait V.Anandakrishnan Department of mechanical Engineering Chendhuran College of Engineering and Technology Department of Production Engineering National Institute of Technology

The cold upsetting studies were carried out for the aluminium metal matrix hybrid composites in the present study. Aluminium metal matrix hybrid composites were synthesised through powder metallurgy route from ball-milled powders to yield the following compositions：Al ＋ 2.5 wt% TiO2＋ 2 wt% Gr, Al ＋ 2.5 wt% TiO2＋ 4 wt% Gr, Al ＋ 5.0 wt% TiO2＋ 2 wt% Gr and Al ＋ 5.0 wt% TiO2＋ 4 wt% Gr. The compaction process was carried out using suitable punch and die in 40 k N hydraulic press, and sintering was done in an electric muffle furnace at the temperature of 590 °C for 3 h. The sintered preforms were subjected to incremental compressive loading of 10 k N until the cracks were found at the free surface. The true axial stress, true hoop stress, true hydrostatic stress and true effective stress were calculated for all the preforms, and all these stresses are correlated with the true axial strain. The stress ratio parameters（rz/reff, rh/reff, rz/rmand rh/rm） of the all preforms were correlated with true axial strain. The maximum true axial stress, true hoop stress, true effective stress and hydrostatic static stress are obtained for the composite containing5 wt% of TiO2 and 4 wt% of graphite and the minimum ones are obtained for composite containing 2.5 wt% of TiO2 and 2 wt% of graphite.

关键词： metal matrix composites Cold upsetting Powder metallurgy

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HEALTHCARE: A COmPLEX SERVICE SYSTEm

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Journal of Systems Science and Systems Engineering 2009年第3期18卷 257-282页

作者： James m. TIEN Pascal J. GOLDSCHmIDT-CLERmONT Dean College of Engineering University of Miami Coral GablesFlorida USA Dean Miller School of Medicine University of Miami Coral GablesFlorida USA

Healthcare is indeed a complex service system, one requiring the technobiology approach of systems engineering to underpin its development as an integrated and adaptive system. In general, healthcare services are carried out with knowledge-intensive agents or components which work together as providers and consumers to create or co-produce value. Indeed, the engineering design of a healthcare system must recognize the fact that it is actually a complex integration of human-centered activities that is increasingly dependent on information technology and knowledge. Like any service system, healthcare can be considered to be a combination or recombination of three essential components - people （characterized by behaviors, values, knowledge, etc.）, processes （characterized by collaboration, customization, etc.） and products （characterized by software, hardware, infrastructures, etc.）. Thus, a healthcare system is an integrated and adaptive set of people, processes and products. It is, in essence, a system of systems which objectives are to enhance its efficiency （leading to greater interdependency） and effectiveness （leading to improved health）. Integration occurs over the physical, temporal, organizational and functional dimensions, while adaptation occurs over the monitoring, feedback, cybernetic and learning dimensions. In sum, such service systems as healthcare are indeed complex, especially due to the uncertainties associated with the human-centered aspects of these systems. moreover, the system complexities can only be dealt with methods that enhance system integration and adaptation.

关键词： Services healthcare system integration system adaptation system complexity system of systems customization co-production decision informatics real-time decision making

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material Research Related to Structural Pavement Failure on motorway A32 in the Netherlands

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武汉理工大学学报 2010年第17期32卷 8-17页

作者： HOUBEN L J m mOLENAAR A A A ERKENS S m J G Faculty Civil Engineering and Geosciences Delft University of Technology ministry of Traffic Public Works and Water ManagementCentre for Transport and Navigation

In 2008 structural failures occurred on the asphalt pavement,with a hydraulic blast furnace slag base,of the motorway A32 (constructed in 1986～1988) in the Netherlands. Within a few weeks serious depressions occurred,in which the asphalt pavement was full of cracks and the base had a very low stiffness. In 2008 and 2009 the pavement including the base was rehabilitated over a length of 10 *** Dutch ministry of Public Works has initiated an extensive research into the risks of occurrence of this type of unexpected structural damages on the main road network in the Netherlands. Among many other things this research includes material research into the base material of the A32 to find the cause of the structural *** total 130 cores,divided over 26 cross-sections,were drilled from the A32. The cross-sections were divided over 3 areas,with a high and low base stiffness respectively and also at heaves that had grown into the pavement since 1998. In areas with high base stiffness the cores mainly contained bound base material,in areas with low base stiffness mainly granular material and at the heaves it was a mix thereof. Standard (static) and dynamic crushing tests were done on the granular material. Dynamic and monotonic indirect tensile tests and compression tests were performed on the bound material. In all cases no systematic difference was found between the mechanical properties of the blast furnace slag base material from the heavily loaded right traffic lane and the material from the other *** is concluded that the pavement failure on the A32 is introduced by the occurrence of full depth asphalt fatigue cracks in the pavement that was originally designed for 12 years (but was never strengthened) in areas where the base stiffness always has been low or became low through crushing (that also has resulted in the heaves). Penetrated rainwater then has weakened the base and pumping has occurred,resulting into loss of bearing capacity and decrease of vo

关键词： structural failure blast furnace slags base laboratory testing

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