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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

Spatially enabling Australia-the next decade

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International Journal of Digital Earth 2010年第1期3卷 91-107页

作者： peter Woodgate Australian Cooperative Research Centre for Spatial Information 723 Swanston StreetUniversity of MelbourneMelbourneVIC 3010Australia

A strategy for the development of the Australian spatial information industry called‘Spatially Enabling Australia’has recently been developed by the Cooperative Research Centre for Spatial *** comprises three fundamental research programs and an integrated applications *** Program 1,‘Positioning,’underpins a full framework of continuous operating reference stations to ultimately enable all of continental Australia to be capable of realtime precise positioning services based on global navigation satellite *** Program 2,‘Automated Spatial Information Generation,’addresses complex processing of multiple remote sensing *** Program 3,‘Spatial Infrastructures,’helps form the foundation for development of an Australian Spatial Marketplace that will make accessible vast amounts of government held data under a new licensing and access regime which supports combination with user-generated content from the mass *** three core programs are integrated with Program 4,‘Applications,’to support users from the Health,Defense and Security,Energy and Utilities,Urban Development,and Agriculture-Natural Resources-Climate Change *** 4 drives outputs from the three core research programs in sector-specific deployments for high *** will see a rapid acceleration of the use and value adding of information products and services that utilize spatial *** are considerable research and development challenges that must be met in order to achieve the strategic outcomes.

关键词： Australia spatial information positioning marketplace research

Counter Rotating Fans- An Aircraft Propulsion for the Future?

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Journal of Thermal Science 2003年第2期12卷 97-103页

作者： peter Schimming DLR Institute for Propulsion TechnologyCologneGermany

In the mid seventies a new propulsor for aircraft was designed and investigated - the so-called PROPFAN. With regard to the total pressure increase, it ranges between a conventional propeller and a turbofan with very high bypass ratio. This new propulsion system promised a reduction in fuel consumption of 15 to 25% compared to engines at that time.A lot of propfans (Hamilton Standard, USA) with different numbers of blades and blade shapes have been designed and tested in wind tunnels in order to find an optimum in efficiency, Fig.1. Parallel to this development GE, USA, made a design of a counter rotating unducted propfan, the so-called UDF, Fig.2. A prototype engine was manufactured and investigated on an in-flight test bed mounted at the MD82 and the B727. Since that time there has not been any further development of propfans (except AN 70 with NK 90-engine, Ukraine, which is more or less a propeller design) due to relatively low fuel prices and technical obstacles. Only technical programs in different countries are still going on in order to prepare a data base for designing counter rotating fans in terms of aeroacoustics, aerodynamics and aeroelasticities. In DLR, Germany, a lot of experimental and numerical work has been undertaken to understand the physical behaviour of the unsteady flow in a counter rotating fan.

关键词： propfan counter rotation unsteady aerodynamics active noise control aeroelasticities.

THE USE OF PLANE WAVES TO APPROXIMATE WAVE PROPAGATION IN ANISOTROPIC MEDIA

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Journal of Computational Mathematics 2007年第3期25卷 350-367页

作者： Tomi Huttunen peter Monk Department of Physics University of KuopioP.O.Box 1627FIN-70211 KuopioFinland Department of Mathematical Sciences University of DelawareNewarkDE 19716USA

In this paper we extend the standard Ultra Weak Variational Formulation （UWVF） of Maxwell＇s equations in an isotropic medium to the case of an anisotropic medium. We verify that the underlying theoretical framework carries over to anisotropic media （however error estimates are not yet available） and completely describe the new scheme. We then consider TM mode scattering, show how this results in a Helmholtz equation in two dimensions with an anisotropic coefficient and demonstrate how to formulate the UWVF for it. In one special case, convergence can be proved. We then show some numerical results that suggest that the UWVF can successfully simulate wave propagation in anisotropic media.

关键词： Ultra weak Maxwell Plane wave Anisotropic medium.

PRECONDITIONING BLOCK LANCZOS ALGORITHM FOR SOLVING SYMMETRIC EIGENVALUE PROBLEMS

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Journal of Computational Mathematics 2000年第4期18卷 365-374页

作者： Hua Dai peter Lancaster Nanjing University of Aeronautics and Astronautics Naming210018China University of Calgary CalgaryCanada

A preconditioned iterative method for computing a few eigenpairs of large sparse symmetric matrices is presented in this paper. The proposed method which combines the preconditioning techniques with the efficiency of block Lanczos algorithm is suitable for determination of the extreme eigenvalues as well as their multiplicities. The global convergence and the asymptotically quadratic convergence of the new method are also demonstrated. [ABSTRACT FROM AUTHOR]

关键词： eigenvalue eigenvector sparse matrices Lanczos method preconditioning

Maintaining biodiversity will define our long-term success

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Plant Diversity 2020年第4期42卷 211-220页

作者： peter Raven Mathis Wackernagel Missouri Botanical Garden 4344 Shaw BlvdSt.LouisMO63110USA Global Footprint Network 1528 Webster StreetSuite 11OaklandCA94612USA

Human beings are not only a part of our planet's ecosystems,but also,they are massively overusing *** makes ecosystem protection,including biodiversity preservation,vital for humanity's *** speed and scale of the threat are unprecedented in human *** long arch of evolution has been confronted with such a high level of human impact,that we are now facing the sixth mass extinction event,66 million years after the last *** threat heightens the imperative for bold human *** paper identifies three strategies for such an ***,and possibly most challenging,human demand needs to be curbed so it fits within the bounds of what Earth's ecosystems can *** meeting this quantitative goal,biodiversity preservation efforts will not be able to get ***,in the transition time,we must focus on those locations and areas where most biodiversity is *** a focus on‘hotspots’will help safeguard the largest portion of biodiversity with least ***,to direct biodiversity preservation strategies,we need to much better document the existence and distribution of biodiversity around the *** information technologies could help with this critical *** conclusion,biodiversity preservation is no longer just a concern for specialized biologist but is becoming a societal necessity if humanity wants to have a stable future.

关键词： Biodiversity Hotspots Biocapacity Conservation strategy

Emerging and Innovative Materials for Hydropower Engineering Applications:Turbines,Bearings,Sealing,Dams and Waterways,and Ocean Power

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Engineering 2022年第1期8卷 148-158页

作者： Emanuele Quaranta peter Davies European Commission Joint Research Centre Ispra 21027Italy Marine Structures Laboratory IFREMER Centre BretagnePlouzané29280France

The hydropower sector is currently experiencing several technological *** technologies and practices are emerging to make hydropower more flexible and more *** materials have also been recently developed to increase performance,durability,and reliability;however,no systematic discussions can be found in the ***,in this paper,novel materials for hydropower applications are presented,and their performance,advantages,and limitations are *** example,composites can reduce the weight of steel equipment by 50%to 80%,polymers and superhydrophobic materials can reduce head losses by 4%to 20%,and novel bearing materials can reduce bearing wear by 6%.These improvements determine higher efficiencies,longer life span,waste reduction,and maintenance needs,although the initial cost of some materials is not yet competitive with respect to the costs of traditional *** novel materials are described here based on the following categories:novel materials for turbines,dams and waterways,bearings,seals,and ocean hydropower.

关键词： Bearing Composite Dam Hydropower Material Ocean Seal Turbine

MADM gives new insights into gliomagenesis

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Journal of Molecular Cell Biology 2011年第5期3卷 273-275页

作者： Liang Lei peter Canoll Department of Pathology and Cell Biology Columbia UniversityNew YorkNY 10032USA

In their recent paper,Liu et al.(2011)make use of an elegant genetic mouse model to study the formation of malignant brain *** findings add strong support to the growing body of evidence from several labs showing that some gliomas arise from oligodendrocyte precursor cells(OPCs).They also provide new insights,and raise new questions,regarding where,when,and how malignant gliomas form.

关键词： glioma al. malignant

On variations of m, n-simply presented abelian p-groups

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Science China Mathematics 2014年第9期57卷 1771-1784页

作者： DANCHEV peter Department of Mathematics University of Plovdiv

We define a few new classes of p-primary abelian groups,and study their crucial properties,one of which is the so-called Nunke’s-esque *** are also closely related to n-simply presented groups from Keef and Danchev(2... 详细信息

关键词： m n-simply presented groups m n-totally projective groups potentially m n-simply presented groups completely m n-simply presented groups absolutely m n-simply presented groups