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国际原子能机构通报 2002年第1期44卷 7-10页

作者： JEFFREY sachs 美国哥伦比亚大学地球研究所

世界上的不发达国家问题,特别是最低收入国家问题,远远不止是经济战略问题。我们发现,世界很多地区缺乏解决健康、粮食供给、营养、环境管理、气候改变等方面关键问题所必需的科学技术,而这些问题给经济发展设置了巨大的障碍。作为一个... 详细信息

世界上的不发达国家问题,特别是最低收入国家问题,远远不止是经济战略问题。我们发现,世界很多地区缺乏解决健康、粮食供给、营养、环境管理、气候改变等方面关键问题所必需的科学技术,而这些问题给经济发展设置了巨大的障碍。作为一个经济学家。

关键词：低收入国家国家问题粮食供给气候改变环境管理经济发展研究与发展农业生产率私有部门国际原子能机构

Assessing fire severity in Turkey's forest ecosystems using spectral indices from satellite images

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Journal of Forestry Research 2023年第6期34卷 1747-1761页

作者： Coşkun Okan güney Ahmet Mert Serkan gülsoy Department of Forest Fires Aegean Forestry Research Institute35430 IzmirTurkey Department of Wildlife Ecology and Management Faculty of ForestryIsparta University of Applied Science32260 IspartaTurkey Department of Soil Science and Ecology Faculty of ForestryIsparta University of Applied Science32260 IspartaTurkey

Fire severity classifications determine fire damage and regeneration potential in post-fire areas for effective implementation of restoration *** fire damage varies according to vegetation and fire characteristics,regional assessment of fire severity is *** objectives of this study were:(1)to test the performance of different satellite imagery and spectral indices,and two field—measured severity indices,CBI(Composite Burn Index)and geoCBI(geometrically structured Composite Burn Index)to assess fire severity;(2)to calculate classification thresholds for spectral indices that performed best in the study areas;and(3)to generate fire severity maps that could be used to determine the ecological impact of forest *** large fires in Pinus brutia(Turkish pine)and Pinus nigra *** ***(Anatolian black pine)—dominated forests during 2020 and 2021 were selected as study *** results show that geoCBI provided more reliable estimates of field—measured fire severity than *** Sentinel-2 and Landsat-8/OLI images performed similarly well,MODIS performed *** severity classification thresholds were determined for Sentinel-2 based RdNBR,dNBR,dSAVI,dNDVI,and dNDMI and Landsat-8/OLI based dNBR,dNDVI,and *** several spectral indices,the highest accuracy for fire severity classification was found for Sentinel-2 based RdNBR(72.1%)and Landsat-8/OLI based dNBR(69.2%).The results can be used to assess and map fire severity in forest ecosystems similar to those in this study.

关键词： Remote sensing Forest fire Fire severity Spectral indices Composite burn index

Investigation on 3Dt wake flow structures of swimming bionic fish

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Acta Mechanica Sinica 2012年第5期28卷 1494-1508页

作者： g.-X.Shen g.-K.Tan g.-J.Lai Fluid Mechanics Institute Beihang University

A bionic experimental platform was designed for the purpose of investigating time accurate three-dimensional flow field, using digital particle image velocimetry （DSPIV）. The wake behind the flapping trail of a robotic fish model was studied at high spatial resolution. The study was performed in a water channel. A robot fish model was designed and built. The model was fixed onto a rigid support frame- work using a cable-supporting method, with twelve stretched wires. The entire tail of the model can perform prescribed motions in two degrees of freedom, mainly in carangiform mode, by driving its afterbody and lunate caudal fin respectively. The DSPIV system was set up to operate in a trans- lational manner, measuring velocity field in a series of parallel slices. Phase locked measurements were repeated for a number of runs, allowing reconstruction of phase average flow field. Vortex structures with phase history of the wake were obtained. The study reveals some new and complex three-dimensional flow structures in the wake of the fish, including ＂reverse hairpin vortex＂ and ＂reverse Karman S-H vortex rings＂, allowing insight into physics of this complex flow.

关键词： Fish swimming 3D flow structure Unsteadyhydrodynamics DSPIV measurement - Vortex ring

Suppression of Self-Discharge in Aqueous Supercapacitor Devices Incorporating Highly Polar Nanofiber Separators

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Energy & Environmental Materials 2023年第3期6卷 74-86页

作者： Wesley g.Buxton Simon g.King Vlad Stolojan Advanced Technology Institute University of SurreyGuildford SurreyGU27XHUK

One of the major problems limiting the applications of electric double-layer(EDLC)supercapacitor devices is their inability to maintain their cell voltage over a significant ***-discharge is a spontaneous decay in charged energy,often resulting in fully depleted devices in a matter of ***,a new method for suppressing this self-discharge phenomenon is proposed by using directionally polarized piezoelectric electrospun nanofiber films as separator *** engineering of polyvinylidene fluoride(PVDF)nanofiber films containing a small concentration of sodium dodecyl sulfate(SDS)results in a high proportion of polarβphases,reaching 380.5%of the total *** polarity into the separator material provides a reverse-diode mechanism in the device,such that it drops from an initial voltage of 1.6 down to 1 V after 10 h,as opposed to 0.3 V with a nonpolarized,commercial separator ***,the energy retained for the polarized separator is 37%and 4%for the nonpolarized separator,making supercapacitors a more attractive solution for long-term energy storage.

关键词： piezoelectric polar nanofibers PVDF separators self-discharge supercapacitors

Effects of precommercial thinning intensity on growth of Fagus orientalis Lipsky stands over 6 years

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Journal of Forestry Research 2022年第3期33卷 937-947页

作者： Deniz güney Fahrettin Atar İbrahim Turna Alkan günlü Department of Forest Engineering Faculty of ForestryKaradeniz Technical UniversityTrabzon61080Turkey Department of Forest Engineering Faculty of ForestryÇankırıKaratekin UniversityÇankırıTurkey

Determining the most suitable intensities for precommercial thinning (PCT) in oriental beech (Fagus orientalis) stands, which cover substantial areas in Turkey and have a high economic and ecological value, is essential to provide higher economic return and obtain well-formed stems. The effects of various rates of PCT interventions on the growth characteristics of natural stands, located in the northern part of Turkey, were explored to determine appropriate thinning rates;24 experimental PCT plots (4 PCT rates × 3 replications × 2 sites) were established in young thicket-stage stands and four precommercial thinning rates such as light (1 – 1.5 m spacing), moderate (1.5−2.0 m spacing) and heavy (2.5–3.0 m spacing) thinning, including a control plot (i.e., untreated), were applied. At the end of the 2007 and 2010 growing seasons, the diameter and height of the trees were measured and growth analyzed based on the 3-year and 6-year incremental growth. PCT levels were found to have significant (P ght, total basal area and total volume increment at the end of each period. The mean diameter and height increment proportionally increased with increasing PCT intensity in the third and the sixth year. In both sites, the moderate PCT provided the greatest total basal area and total volume increment. The early results indicate that the moderate PCT (1.5–2 m spacing) boosted stand development over time.

关键词： Tending operation Stand development Precommercial thinning Thicket stage

Embedded Atom Method-Based geometry Optimization Aspects of Body-Centered Cubic Metals

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Chinese Physics Letters 2013年第5期30卷 112-115页

作者： M.güler E.güler Department of Physics Hitit University19030 CorumTurkey

We present embedded atom method-based geometry optimization calculations for Fe, Cr, Mo, Nb, Ta, V and W body-centered cubic metals with Finnis–Sinclair potentials. After the optimization, we determine their typical elastic constants, bulk modulus, shear modulus, Young's modulus, Poisson's ratios, elastic wave velocities and cohesive energies. Additionally, we perform a benchmark between the experiments and the available density functional theory results. In general, our results show a good consistency with previous findings on the elastic and cohesive energy properties of the considered metals.

关键词： modulus optimization cubic

150 Years(1872-2022)of research on deep-water processes,deposits,settings,triggers,and deformation:A difficult domain of progress,dichotomy,diversion,omission,and groupthink

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Journal of Palaeogeography 2022年第4期11卷 469-564页

作者： g.Shanmugam Department of Earth and Environmental Sciences The University of Texas at ArlingtonArlingtonTX 76019USA

In capturing a snapshot of 150 years(1872-2022)of research on deep-water processes,deposits,settings,triggers,and deformation,the following 22 topics are selected:(1)*** expedition(1872-1876):The discovering of the“Challenger Deep”by the *** in the Mariana Trench has been the single most important achievement in deep-water research.(2)Five pioneers amid 50 notable contributors:***,***,***,***,and ***.(3)Mass transport:Mass-transport deposits(MTD)are the most important deep-water facies in terms of volume,geohazards,and petroleum reservoirs.(4)gravity flows:There are six basic types,namely(a)hyperpycnal flows,(b)turbidity currents,(c)debris flows,(d)liquefied/fluidized flows,(e)grain flows,and(f)thermohaline contour *** debrites are the most important petroleum reservoir *** their popularity,turbidites are not an important reservoir facies.(5)Kelvin-Helmholtz(KH)waves:Turbidites,related to KH waves,with internal hiatus are not qualified to function as predictive facies models;nor are they fit for stratigraphic correlations.(6)High-density turbidity currents(HDTC):Misclassification of density-stratified gravity flows with laminar debris flows and turbulent turbidity currents as HDTC is *** generation of density-stratified gravity flows in flume studies has debunked the concept of HDTC.(7)Classification of turbidites:Contrary to the popular groupthink,turbidites are exclusive deposits of turbidity currents.(8)Bottom currents:The four basic types of deep-marine bottom currents are:(a)thermohaline-induced geotropic contour currents,(b)wind-driven bottom currents,(c)tide-driven bottom currents(mostly in submarine canyons),and(d)internal wave/tide-driven baroclinic currents.(9)Classification of contourites:Contrary to the popular groupthink,contourites are the exclusive deposits of thermohaline-induced geotropic contour currents.(10)Tidal currents in submarine canyons:Th

关键词： Mass transport gravity flows Bottom currents High-density turbidity currents Contour currents Tidal currents Internal waves and tides Kelvin-helmholtz waves Hybrid flows The Bouma Sequence Tsunami waves Deflected sediment plumes Basin-floor fans Tutbidite groupthink Bute Inlet(BC Canada) Soft-Sediment Deformation structures(SSDS)

Breather solutions of modified Benjamin-Bona-Mahony equation

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Chinese Physics B 2021年第2期30卷 220-226页

作者： g T Adamashvili Technical University of georgia Kostava Street 77Tbilisi0179Georgia

New two-component vector breather solution of the modified Benjamin-Bona-Mahony(MBBM)equation is *** the generalized perturbation reduction method,the MBBM equation is reduced to the coupled nonlinear Schr¨odinger equations for auxiliary *** analytical expressions for the profile and parameters of the vector breather oscillating with the sum and difference of the frequencies and wavenumbers are *** two-component vector breather and single-component scalar breather of the MBBM equation is compared.

关键词： modified Benjamin-Bona-Mahony equation generalized perturbation reduction method vector breather nonlinear waves

Dinophysoid dinoflagellates from subphotic depths:Amphisolenia ***,Dinofurcula tricornuta ***.,and Dinophysis profunda ***.(Dinophysales,Dinophyceae)

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Journal of Oceanology and Limnology 2022年第2期40卷 703-711页

作者： Fernando gÓMEZ Department of Biological and Environmental Sciences and Technologies University of SalentoLecce 73100Italy

Three species of dinophysoid planktonic dinoflagellates are described from the eastern Mediterranean *** *** was collected at 70-m depth in the Ionian *** small species showed a more asymmetric midbody and a proportionally longer neck when compared to the closer relative *** individuals of Dinofurcula tricornuta *** at 154-m depth in the Marmara Sea are characterized by three posterior-oriented processes when compared to its congeneric *** is the first record of the genus Dinofurcula beyond the eastern tropical Pacific *** profunda *** at 500-m depth in the Ionian Sea is characterized by ovate hypotheca and a serrate crest-like left sulcal list when compared to its close relative *** findings evidence an undescribed biodiversity in the under-sampled subphotic depths.

关键词： deep ocean Dinophyta Dinoflagellata Mediterranean Sea mesopelagic new species

The turbidite-contourite-tidalite-baroclinite-hybridite problem: orthodoxy vs. empirical evidence behind the “Bouma Sequence”

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Journal of Palaeogeography 2021年第2期10卷 125-156页

作者： g.Shanmugam Department of Earth and Environmental Sciences The University of Texas at ArlingtonTX 76019USA

The underpinning problems of deep-water facies still remain unresolved.(1) The Tb, Tc, and Td divisions of the turbidite facies model, with traction structures, are an integral part of the "Bouma Sequence"(Ta, Tb, Tc, Td, Te).However, deposits of thermohaline contour currents, wind-driven bottom currents, deep-marine tidal currents, and baroclinic currents(internal waves and tides) also develop discrete rippled units, mimicking Tc.(2) The application of "cut-out" logic of sequences, which was originally introduced for the "Bouma Sequence", with sharp basal contacts and sandy divisions containing well-developed traction structures, to muddy contorts with gradational basal contacts and an absence of well-developed traction structures is incongruent.(3) The presence of five internal divisions and hiatus in the muddy contoured facies model is in dispute.(4) Intersection of along slope contour currents with down slope sediment-gravity flows, triggering hybrid flows, also develops traction structures.(5) The comparison of genuine hybrid flows with down slope flow transformation of gravity flows is inconsistent with etymology of the term "hybrid".(6) A reexamination of the Annot Sandstone at the Peira Cava type locality in SE France fails to validate either the orthodoxy of five internal divisions of the "Bouma Sequence" or their origin by turbidity currents. For example, the "Ta" division is composed of amalgamated units with inverse grading and floating mudstone clasts, suggesting a mass-transport deposit(MTD). The "Tb" and "Tc" divisions are composed of double mud layers and sigmoidal cross bedding, respectively, which suggest a tidalite origin.(7) Although it was reasonable to introduce a simplistic "Bouma Sequence" in 1962, at a time of limited knowledge on deep-water processes, it is obsolete now in 2021 to apply this model to the rock record amid a wealth of new knowledge.(8)The disconnect between 12 observed, but questionable, modern turbidity currents and over 10,

关键词： Turbidity currents Contour currents Tidal currents Internal waves and tides Hybrid flows The Bouma Sequence BCRS(i.e. bottom-current reworked sands)