1,134 research outputs found
NMR Determination of an Incommensurate Helical Antiferromagnetic Structure in EuCo2As2
We report Eu, As and Co nuclear magnetic resonance
(NMR) results on EuCoAs single crystal. Observations of Eu and
As NMR spectra in zero magnetic field at 4.3 K below an
antiferromagnetic (AFM) ordering temperature = 45 K and its
external magnetic field dependence clearly evidence an incommensurate helical
AFM structure in EuCoAs. Furthermore, based on Co NMR data in
both the paramagnetic and the incommensurate AFM states, we have determined the
model-independent value of the AFM propagation vector = (0, 0, 0.73
0.07)2/ where is the lattice parameter. Thus the
incommensurate helical AFM state was characterized by only NMR data with
model-independent analyses, showing NMR to be a unique tool for determination
of the spin structure in incommensurate helical AFMs.Comment: 6 pages, 4 figures, accepted for publication in Phys.Rev.
The structure of the space of affine Kaehler curvature tensors as a complex module
We use results of Matzeu and Nikcevic to decompose the space of affine
Kaehler curvature tensors as a direct sum of irreducible modules in the complex
settin
Características da madeira de algumas espécies de eucalipto plantadas no Brasil.
bitstream/item/94756/1/doc38.pd
Propriedades da madeira de Taxodium distichum (L.) Rich.
bitstream/CNPF-2009-09/43373/1/Com_tec108.pd
The rate of convergence of Euler approximations for solutions of stochastic differential equations driven by fractional Brownian motion
The paper focuses on discrete-type approximations of solutions to
non-homogeneous stochastic differential equations (SDEs) involving fractional
Brownian motion (fBm). We prove that the rate of convergence for Euler
approximations of solutions of pathwise SDEs driven by fBm with Hurst index
can be estimated by ( is the diameter of
partition). For discrete-time approximations of Skorohod-type quasilinear
equation driven by fBm we prove that the rate of convergence is .Comment: 21 pages, (incorrect) weak convergence result removed, to appear in
Stochastic
NMR studies of the incommensurate helical antiferromagnet EuCo2P2 : determination of the antiferromagnetic propagation vector
Recently Ding et al. [Phys. Rev. B 95, 184404 (2017)] reported that their
nuclear magnetic resonance (NMR) study on EuCoAs successfully
characterized the antiferromagnetic (AFM) propagation vector of the
incommensurate helix AFM state, showing that NMR is a unique tool for
determination of the spin structures in incommensurate helical AFMs. Motivated
by this work, we have carried out Eu, P and Co NMR
measurements on the helical antiferromagnet EuCoP with an AFM ordering
temperature = 66.5 K. An incommensurate helical AFM structure was
clearly confirmed by Eu and P NMR spectra on single crystalline
EuCoP in zero magnetic field at 1.6 K and its external magnetic field
dependence. Furthermore, based on Co NMR data in both the paramagnetic
and the incommensurate AFM states, we have determined the model-independent
value of the AFM propagation vector k = (0, 0, 0.73 0.09)2/ where
is the -axis lattice parameter. The temperature dependence of k is also
discussed.Comment: 8 pages, 10 figures, accepted for publication in Phys. Rev. B. arXiv
admin note: substantial text overlap with arXiv:1704.0629
INVESTIGATION ON VOLUME VARIATION FOR ALPHA STIRLING ENGINES ON ISOTHERMAL MODEL
The usage of renewable energies is approximately 11% of the matrix energy worldwide. In countries known for its renewable sources, such as Brazil, the percentage is close to 38%. The importance to study Stirling engines and propose a prototype is that they are a feasible alternative for generation of power and electricity when considering low quality sources such as solar and waste energy. This paper will compare two different approaches of the volume variation, sinusoidal and kinematic, using an isothermal model that represents the Stirling engines. The comparison is made for an a type engine. Such approaches are capable of representing an estimative of work and power output for Stirling engines since the difference of results for these approaches are 8.07% for power output. As both approaches are a valid choice for analyzing the Stirling engine cycle, the availability of the data determines which approach is the most suitable for characterizing the engine performance
Comparação entre métodos de avaliação da estabilidade fenotípica e adaptabilidade aplicados a dados de Eucalyptus cloeziana (F. MUELL).
Foram avaliadas a estabilidade fenotipica e adaptabilidade de 62 progenies pertencentes a 4 procedencias de Eucalyptus cloeziana, estabelecidas em seis locais do Brasil. Foram aplicados e comparados os metodos biometricos de Yates & Cochran, Plaisted & Peterson, Wricke, Finlay & Wilkinson e Eberhart & Russel. Para adaptabilidade, os resultados revelaram uma concordancia entre os metodos de Eberhart & Russel e Finlay & Wilkinson, exceto que o de Finlay & Wilkinson tendeu a apresentar melhores ajustes das similares pela metodologias de Eberhart & Russel, Wricke e Plaisted & Peterson, os quais discordaram dos obtidos pelo metodo de Yates & Cochran. Nao foram detectadas correlacoes entre estabilidade e adaptablidade com produtividade media, tendo sido identificadas progenies de alta produtividade, alta estabilidade e adaptabilidade geral
Ampliação da rede experimental do programa de melhoramento de eucalipto no CNPF/Embrapa.
Edição dos Anais do Congresso Florestal Brasileiro, 6., 1990, Campos do Jordão
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