Hacia la Armonización de Modelos de Requisitos de Seguridad

La ingeniería de requisitos de seguridad se ha convertido en un campo vital en el desarrollo de sistemas informáticos. En la actualidad, se utilizan lenguajes, técnicas, artefactos, diagramas; resumidos todos como modelos, para la representación de requisitos de seguridad desde las etapas más tempranas del desarrollo. En el presente trabajo se describen los pasos a seguir en un proceso de armonización de dichos modelos. Desde la identificación de la necesidad de armonización, hasta la estructura de una propuesta inicial para llevarla a cabo, basados en los conceptos de la Ingeniería Dirigida por Modelos (MDE). Como parte de esos pasos, se hace especial hincapié en la presentación de los resultados de una revisión sistemática de la literatura en el campo tratado; así como los de una comparación entre los modelos obtenidos, orientada a justificar la necesidad y viabilidad del proceso armonizador.Sociedad Argentina de Informática e Investigación Operativ

SILVERING OF CUCURBITA MOSCHATA (DUCHESNE) POIR ASSOCIATED WITH BEMISIA TABACI GENN. (HOMOPTERA: ALEYRODIDAE) IN PUERTO RICO

SILVERING OF CUCURBITA MOSCHATA (DUCHESNE) POIR ASSOCIATED WITH BEMISIA TABACI GENN. (HOMOPTERA: ALEYRODIDAE) IN PUERTO RIC

PRELIMINARY EVALUATION OF COMMERCIAL HYBRIDS AND OPEN POLLINATED EGGPLANT CULTIVARS

PRELIMINARY EVALUATION OF COMMERCIAL HYBRIDS AND OPEN POLLINATED EGGPLANT CULTIVAR

EXTENDING THE TOMATO SEASON IN PUERTO RICO: PROBLEMS OF SUMMER PRODUCTION

Commercial varieties and breeding lines of tomato were evaluated over three planting dates (April, May, June) in 1988 and 1989 at Juana Diaz, Puerto Rico in order to study the effects of planting date, variety, and planting date by variety interaction of summer tomato production. In addition, the 1989 plantings included sprayed and nonsprayed plots at every planting date to evaluate the importance of insect pests particularly pinworm. While average yield over all varieties decreased markedly with later planting dates, heat tolerant varieties 'Heatwave' and 'Capitan' maintained excellent yields (up to 70,000 kg/ha) in the April and May planting dates and good yields (45,000 kg/ha) in the June planting. Tomato pinworm populations and damage were high at the beginning of the summer, decreased and then increased again. Use of a heat tolerant variety is essential for successful summer tomato production

Improvement of the intergranular pinning energy in uniaxially compacting (Bi-Pb) 2Sr 2Ca 2Cu 3O 10+δ ceramic samples

Measurements of the electrical resistivity as a function of temperature, ρ(T), for different values of applied magnetic field, B a (0 ≤ B a ≤ 50 mT), were performed in polycrystalline samples of Bi 1.65 Pb 0.35 Sr 2Ca 2 Cu 3O 10+δ subjected to different uniaxial compacting pressure (UCP). We have found appreciable differences in the grain orientation between samples by using X-ray diffractometry. From the X-ray diffraction patterns performed, in powder and pellet samples, we have estimated the Lotgering factor along the (00l) direction, F (00l) . The results indicate that F (00l) increases ~23% with increasing UCP suggesting that grains of these samples are preferentially aligned along the c-axis, which is parallel to the compacting direction. The resistive transition of the samples have been interpreted in terms of the thermally activated flux-creep model. In addition, the effective intergranular pinning energy, U 0, have been determined for different applied magnetic field. The magnetic field dependence of U 0, for B a > 8 mT, was found to follow a H - α dependence with α = 0.5 for all samples. The analysis of the experimental data strongly suggested that increasing UCP results in appreciable changes in both the grain alignment and the grain connectivity of the samples. We have successfully interpreted the data by considering the existence of three different superconducting levels within the samples: the superconducting grains, the weak-links, and the superconducting clusters. Copyright EDP Sciences/Società Italiana di Fisica/Springer-Verlag 200774.72.Hs Bi-based cuprates, 74.81.Bd Granular, melt-textured, amorphous and composite superconductors, 74.25.Fy Transport properties (electric and thermal conductivity, thermoelectric effects, etc.), 74.25.Qt Vortex lattices, flux pinning, flux creep,

Temperature Dependence of the Intergranular Critical Current Density in Uniaxially Pressed Bi(1.65)Pb(0.35)Sr(2)Ca(2)Cu(3)O(10+delta) Samples

We have studied the normal and superconducting transport properties of Bi(1.65)Pb(0.35)Sr(2)Ca(2)Cu(3)O(10+delta) (Bi-2223) ceramic samples. Four samples, from the same batch, were prepared by the solid-state reaction method and pressed uniaxially at different compacting pressures, ranging from 90 to 250 MPa before the last heat treatment. From the temperature dependence of the electrical resistivity, combined with current conduction models for cuprates, we were able to separate contributions arising from both the grain misalignment and microstructural defects. The behavior of the critical current density as a function of temperature at zero applied magnetic field, J (c) (T), was fitted to the relationship J (c) (T)ae(1-T/T (c) ) (n) , with na parts per thousand 2 in all samples. We have also investigated the behavior of the product J (c) rho (sr) , where rho (sr) is the specific resistance of the grain-boundary. The results were interpreted by considering the relation between these parameters and the grain-boundary angle, theta, with increasing the uniaxial compacting pressure. We have found that the above type of mechanical deformation improves the alignment of the grains. Consequently the samples exhibit an enhance in the intergranular properties, resulting in a decrease of the specific resistance of the grain-boundary and an increase in the critical current density.Brazilian agencies Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)[05/53241-9]Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Brazilian agencies Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)[2009/51562-3]Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)[473932/2007-5]Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)[308706/2007-2