4 resultados para polarity

em Universidade Federal do Rio Grande do Norte(UFRN)


Relevância:

10.00% 10.00%

Publicador:

Resumo:

This work has risen from the researcher s pedagogical practice at a technical school in Natal, and it aims to observ how affectiveness is noticed by the students in their English classes, since we can have an idea of technicist teaching, which foccus on the acquisition of technical abilities. As cognition and affectiveness are considered indivisible elements in this research, we tried to identify the linguistic signs that express the students representations about affectiveness in their English classes. We used the Systemic Functional Linguistics approach to study the Ideational metafunction of Halliday (1994), by means of the transitivity system, to show how the clauses are used to illustrate these representations, and the interpersonal metafunction, that deals with the relationship between the teacher and the students. We tried to identify the most common processes (HALLIDAY, 1994) mentioned by the 68 students who participated in this work. We used learning narratives (BARCELOS, 2006) submitted to Wordsmith Tools computing program (SCOTT, 2009), whose results indicate the most frequent lexical items found in their narratives. The lexical choices seem to indicate that affectiveness is noticed as a composing element of the English classes in that school. There are representations of interacting classes, where the students needs are considered. These representations are built in the relationship of the students and the teacher, and they are grammatically realized by means of the polarity adjunct no , the intensity adjunct very , and the nominal group the teacher . The relational and mental processes (be) and (like) are the most used in their narratives, and we also observe that affectiveness and disponibility to help the students are considered the most important attitudes in their representations. The Appraisal system is used to analise the choices related to the attitudes and judgement of the students, that show appreciation for interacting classes, but there is still authorithary berhavior from the teacher in the English classes

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The effect of confinement on the magnetic structure of vortices of dipolar coupled ferromagnetic nanoelements is an issue of current interest, not only for academic reasons, but also for the potential impact in a number of promising applications. Most applications, such as nano-oscillators for wireless data transmission, benefit from the possibility of tailoring the vortex core magnetic pattern. We report a theoretical study of vortex nucleation in pairs of coaxial iron and Permalloy cylinders, with diameters ranging from 21nm to 150nm, and 12nm and 21nm thicknesses, separated by a non-magnetic layer. 12nm thick iron and Permalloy isolated (single) cylinders do not hold a vortex, and 21nm isolated cylinders hold a vortex. Our results indicate that one may tailor the magnetic structure of the vortices, and the relative chirality, by selecting the thickness of the non-magnetic spacer and the values of the cylinders diameters and thicknesses. Also, the dipolar interaction may induce vortex formation in pairs of 12nm thick nanocylinders and inhibit the formation of vortices in pairs of 21nm thick nanocylinders. These new phases are formed according to the value of the distance between the cylinderes. Furthermore, we show that the preparation route may control relative chirality and polarity of the vortex pair. For instance: by saturating a pair of Fe 81nm diameter, 21nm thickness cylinders, along the crystalline anisotropy direction, a pair of 36nm core diameter vortices, with same chirality and polarity is prepared. By saturating along the perpendicular direction, one prepares a 30nm diameter core vortex pair, with opposite chirality and opposite polarity. We also present a theoretical discussion of the impact of vortices on the thermal hysteresis of a pair of interface biased elliptical iron nanoelements, separated by an ultrathin nonmagnetic insulating layer. We have found that iron nanoelements exchange coupled to a noncompensated NiO substrate, display thermal hysteresis at room temperature, well below the iron Curie temperature. The thermal hysteresis consists in different sequences of magnetic states in the heating and cooling branches of a thermal loop, and originates in the thermal reduction of the interface field, and on the rearrangements of the magnetic structure at high temperatures, 5 produce by the strong dipolar coupling. The width of the thermal hysteresis varies from 500 K to 100 K for lateral dimensions of 125 nm x 65 nm and 145 nm x 65 nm. We focus on the thermal effects on two particular states: the antiparallel state, which has, at low temperatures, the interface biased nanoelement with the magnetization aligned with the interface field and the second nanoelement aligned opposite to the interface field; and in the parallel state, which has both nanoelements with the magnetization aligned with the interface field at low temperatures. We show that the dipolar interaction leads to enhanced thermal stability of the antiparallel state, and reduces the thermal stability of the parallel state. These states are the key phases in the application of pairs of ferromagnetic nanoelements, separated by a thin insulating layer, for tunneling magnetic memory cells. We have found that for a pair of 125nm x 65nm nanoelements, separated by 1.1nm, and low temperature interface field strength of 5.88kOe, the low temperature state (T = 100K) consists of a pair of nearly parallel buckle-states. This low temperature phase is kept with minor changes up to T= 249 K when the magnetization is reduced to 50% of the low temperature value due to nucleation of a vortex centered around the middle of the free surface nanoelement. By further increasing the temperature, there is another small change in the magnetization due to vortex motion. Apart from minor changes in the vortex position, the high temperature vortex state remains stable, in the cooling branch, down to low temperatures. We note that wide loop thermal hysteresis may pose limits on the design of tunneling magnetic memory cells

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This research aims to focus on the education problem, since its source of development is the Research Base: Teachers Training and Qualification of UFRN. Therefore, we seek guidance in the beliefs in sustainability to propose plausible alternatives to promote the education process of UFRN administration undergraduates in order to meet the demands of a market-oriented society, since the market trend is to evolve from environmental guided activities, and future administrators should be trained to meet those conditions. The need to develop an instrument capable of understanding the beliefs of undergraduates on the sustainability problem becomes the object of analysis. This research aims to develop a normative questionnaire to study administration students beliefs in sustainability. The complexity and sensitivity of this research required the integration of various methodological procedures. These proposals were made as follows: analysis and selection of literature, expert validation procedures and psychometric methods and statistics. As for the literature, types of sustainability were identified and categorized, such as: political, social, economic and environmental sustainability. However, it is understood that the educational type, although included in all of those, needed to be converted into another type to fit the theme, since education is believed to be the best way to raise awareness about sustainability. Thus, it was required the categorization of the types, which was defined using criteria such as: contexts, objectives, goals, pathways and hypotheses. The normative questionnaire was the guiding instrument to investigate the role of administration students, regarding the level of knowledge established and regulated by social educational context, especially by becoming a basic condition for carrying out research on beliefs. The study confirmed that the types of sustainability - political, social, economic, environmental and educational - for having institutionalized literatures as sources, in international and national levels, are representative in the identification of future administrators. Therefore, it is believed that the types of sustainability categorized to provide a characterization of sustainability include the structuring of knowledge for undergraduates. The economic and political types, however, were not as representative with respect to their typicality and polarity indices as the educational, environmental and social ones. Although the beliefs of the undergraduates show how much they share ideas on all types, they present more identification with the educational and environmental types. Finally, it is expected that this instrument be subject to application in similar contexts so that it can ascertain whether such statements are part of the knowledge structure of future administrators from other institutions. Therefore, it is expected this strategy to strengthen the validation of the normative questionnaire

Relevância:

10.00% 10.00%

Publicador:

Resumo:

In this dissertation we studied the seismic activity in the São Caetano county, Pernambuco State, Northeastern Brazil, located near the Pernambuco Lineament. The Pernambuco Lineament is a one of Neoproterozoic continental-scale shear zones that deforms the Borborema province. The seismicity estudied occurred in a NE trending branch of Pernambuco Lineament. The seismic activity in São Caetano started in 2006 and in May 20th, 2006 a 4,0 mb earthquake hit there. This was the largest earthquake ever reported in Pernambuco State. This dissertation is the result of a campaign done in the period from Februay 1th 2007 to July 31 th 2007. In this campaign up to nine three-component digital seismographic stations were deployed and the collected data was used to determine hypocenters and focal mechanism. A total of 214 earthquakes, recorded at least by three stations, were analyzed. To determine hypocenters and time origin the HYPO71 program was used assuming a half-space model with parameters : VP (P-wave velocity) equal to 5.90 km/s and the ratio VP/VS 1.70, where VS is the S-wave velocity. The earthquakes hypocentral distribution was approximately 4 km long and agrees with the NE-SW direction of the Pernambuco Lineamento branch. Hypocentres depth range from 2 to 8 km. The composed focal mechanism was made from a group of 14 selected earthquakes. We try firstly to find the fault plane solution matching the polarity distribution at stations, using the FPFIT program. The result was 43 deg ± 15 deg for strike, 59 deg ± 9 deg for dip and -142 deg ± 15 deg for rake. We also fitted a plane using the hypocentral distribution to obtain the dip and azimuth of the hypocentral distribution. The results obtained by this fit were 58 deg for the azimuth, 55 deg for the dip and -155 deg for rake. This result shows a mechanism of a strike-slip dextral fault with a normal component. This dissertation shows, once more, that there is a good correlation between the seismic activity and geological features in the region near the Pernambuco Lineament and its NE branches