Los enfoques de aprendizaje en la universidad : un estudio de caso

En este trabajo se presentan los resultados de una investigación sobre los Enfoques de Aprendizaje correspondientes a 157 estudiantes de las carreras de Psicopedagogía y Ciencias de la Educación de la Facultad de Psicología y Educación de la Pontificia Universidad Católica Argentina (Buenos Aires).* Se utilizó el Cuestionario de Procesos de Estudio, de Biggs- Hernández Pina. Se analizó la predominancia de los enfoques Superficial, Profundo y de Alto Rendimiento en la población estudiada, diferenciando entre motivos y estrategias de aprendizaje. El análisis discriminó el nivel de los alumnos en la carrera (Psicopedagogía). A partir de las conclusiones se hicieron actividades de orientación dirigidas a los docentes para lograr optimizar la acción educativa.

Comparative observation of Ar, Ar-H-2 and Ar-N-2 DC arc plasma jets and their arc root behaviour at reduced pressure

Results observed experimentally are presented, about the DC arc plasma jets and their arc-root behaviour generated at reduced gas pressure without or with an applied magnetic field. Pure argon, argon-hydrogen or argon- nitrogen mixture was used as the plasma-forming gas. A specially designed copper mirror was used for a better observation of the arc-root behaviour on the anode surface of the DC non-transferred arc plasma torch. It was found that in the cases without an applied magnetic field, the laminar plasma jets were stable and approximately axisymmetrical. The arc-root attachment on the anode surface was completely diffusive when argon was used as the plasma-forming gas, while the arc-root attachment often became constrictive when hydrogen or nitrogen was added into the argon. As an external magnetic field was applied, the arc root tended to rotate along the anode surface of the non-transferred arc plasma torch.

环状日冕瞬变的活塞驱动理论

本文用柱面活塞驱动过程模拟环状日冕瞬变现象。用特征线法数值研究在太阳引力作用下活塞的运动过程,得出了符合活塞运动条件及联结条件的等离子体密度分布、流速分布及激波特征。活塞驱动理论所得结果在形态、运动学、动力学及演化方面均与观测一致。

板块运动的模拟实验

本文较详细地分析了板块运动模拟实验的困难性.提出了用物质密度差代替温度差的实验方法,结合离心技术,研究了地幔对流对板块运动的作用,成功地再现了板块运动的流动图案。 通过对上涌流动微分方程组的分析,本文还建立了模拟实验中“模型”与“原型”之间的相似准则D_e=D_m。

Soberania popular e reforma constitucional : acerca da legitimação democrática da mudança constitucional

Discute como os processos de mudança constitucional se relacionam com o princípio da soberania popular. A inadequação das respostas dadas a esse dilema pela teoria constitucional liberal e autoritária provê a oportunidade para, a partir de premissas da teoria discursiva, apontar uma alternativa capaz de conciliar constitucionalismo e democracia. Por fim, as premissas teóricas organizadas ao longo do texto são utilizadas para analisar a proposta de emenda à Constituição n. 157, de 2003, em especial quanto ao papel que a democracia direta exerce (ou pode exercer) na legitimação dos processos de mudança constitucional.

Computation of turbulent-flow in a square duct - aspects of the secondary flow and its origin

A numerical study of turbulent flow in a straight duct of square cross-section is made. An order-of-magnitude analysis of the 3-D, time-averaged Navier-Stokes equations resulted in a parabolic form of the Navier-Stokes equations. The governing equations, expressed in terms of a new vector-potential formulation, are expanded as a multi-deck structure with each deck characterized by its dominant physical forces. The resulting equations are solved using a finite-element approach with a bicubic element representation on each cross-sectional plane. The numerical integration along the streamwise direction is carried out with finite-difference approximations until a fully-developed state is reached. The computed results agree well with other numerical studies and compare very favorably with the available experimental data. One important outcome of the current investigation is the interpretation analytically that the driving force of the secondary flow in a square duct comes mainly from the second-order terms of the difference in the gradients of the normal and transverse Reynolds stresses in the axial vorticity equation.

A discussion about a class of stress intensity factors and its verification

In this paper, new formulae of a class of stress intensity factors for an infinite plane with two collinear semi-infinite cracks are presented. The formulae differ from those gathered in several handbooks used all over the world. Some experiments and finite element calculations have been developed to verify the new formulae and the results have shown its reliability. Finally, the new formulae and the old are listed to show the differences between them.

冲击压缩下玻璃等脆性材料中失效波的研究进展

失效波的研究始于Rasorenov和Kanel发现K19玻璃样品后自由表面速度时程曲线上有反常再压缩信号。失效波是二十世纪九十年代冲击动力学研究领域的一个重要发现，它是指在一维平面应变冲击压缩下，在玻璃等脆性材料中由冲击波引起的一种独特的失效或破坏现象。较为系统地回顾近年来对失效波的研究工作，评述了研究现状、最新结果、发展趋势、研究方法和实验手段，对尚存的问题进行了分析讨论，并介绍了玻璃材料的基本特性。最后简单汇报了作者在这方面的研究工作和取得的阶段性结果。

GCr15钢超高周疲劳行为的实验研究

以GCr15钢为实验材料进行旋转弯曲超高周疲劳行为的实验研究。用光学显微镜和扫描电镜对试样疲劳断口进行观察 ,结果显示 ,疲劳断裂周次从 10 6 直到 4× 10 8,GCr15钢疲劳裂纹大多起源于试样内部 ,裂纹源一般为非金属夹杂物。从内部起裂的试样 ,疲劳寿命一般比从表面起裂试样的寿命长。文中从断裂力学和断裂物理的角度 ,对实验结果和疲劳机理进行分析