701 research outputs found
Traceability for Model Driven, Software Product Line Engineering
Traceability is an important challenge for software organizations. This is true for traditional software development and even more so in new approaches that introduce more variety of artefacts such as Model Driven development or Software Product Lines. In this paper we look at some aspect of the interaction of Traceability, Model Driven development and Software Product Line
Solutions of Podolsky's Electrodynamics Equation in the First-Order Formalism
The Podolsky generalized electrodynamics with higher derivatives is
formulated in the first-order formalism. The first-order relativistic wave
equation in the 20-dimensional matrix form is derived. We prove that the
matrices of the equation obey the Petiau-Duffin-Kemmer algebra. The
Hermitianizing matrix and Lagrangian in the first-order formalism are given.
The projection operators extracting solutions of field equations for states
with definite energy-momentum and spin projections are obtained, and we find
the density matrix for the massive state. The -matrix Schrodinger
form of the equation is derived, and the Hamiltonian is obtained. Projection
operators extracting the physical eigenvalues of the Hamiltonian are found.Comment: 17 pages, minor corrections, published versio
Fe-bearing phases in Antarctic carbonaceous chondrites Yamato-82162 and Yamato-86720: A Mossbauer study
We report the results of variable temperature Mossbauer spectroscopy measurements on samples of Yamato-82162 and Yamato-86720 carbonaceous chondrites. Transmission Mossbauer spectra were taken through the temperature range from 4.2K to 300K. The Mossbauer spectra at room temperature clearly indicate the presence of magnetic splits and quadrupole doublets in both meteorites, which can be attributed to troilite and olivine, respectively. The measurements also indicate the presence of a superparamagnetic component, probably ferryhidrite, in Y-86720 but not in Y-82162. These results are mostly consistent with those obtained by mineralogical studies. However, our Mossbauer measurements indicate the presence of a previously unknown magnetic component having a field of 250kOe in both meteorites; the mineral is unidentified so far. Our study supports the view that these meteorites were affected by thermal metamorphism, and that Y-82162 was less thermally metamorphosed than Y-86720
Principais usos da madeira de reflorestamento.
O plantio de espĂ©cies florestais de rápido crescimento em propriedades rurais traz uma sĂ©rie de benefĂcios indiretos,tais como a ocupação de solos nĂŁo agricultáveis,proteção de nascentes e cursos d'água,recuperação do solo,entre outros.Contudo,a cultura da floresta Ă© tambĂ©m uma atividade econĂ´mica,tal como uma cultura agrĂcola tradicional
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