oalib

OALib Journal期刊

ISSN: 2333-9721

费用:99美元

投稿

时间不限

2019 ( 39 )

2018 ( 345 )

2017 ( 343 )

2016 ( 489 )

自定义范围…

匹配条件: “F.T.;” ,找到相关结果约243156条。
列表显示的所有文章,均可免费获取
第1页/共243156条
每页显示
Cinemática relativística: paradoxo dos gêmeos
Falciano, F.T.;
Revista Brasileira de Ensino de Física , 2007, DOI: 10.1590/S1806-11172007000100006
Abstract: the twin paradox was first formulated almost 100 years ago but still nowadays is one of the best ways to present the dependence on the definition of space and time of the state of motion of the observer. in this paper we present the conventional formulation of the twin paradox pointing out some of its key concepts and analyse one of its modification in which we compactify one of the spatial dimensions. given the compactification, it is no more necessary to accelerate one of the twins to rejoin them. in this way, we circunvent the conventional explanation to the asymmetry between the twins. following this reasoning, we move to clarify the fundamental role played by acceleration and conclude with some comments on synchronization of clocks and observables in special relativity.
Geometria, espa?o-tempo e gravita??o: conex?o entre conceitos da relatividade geral
Falciano, F.T;
Revista Brasileira de Ensino de Física , 2009, DOI: 10.1590/S1806-11172009000400010
Abstract: the theory of general relativity is formulated in a precise, but very complex, mathematical formalism. in spite of being necessary, this mathematical rigour may become an insurmountable obstacle. notwithstanding this theory is grounded in principles and ideas accessible to anyone. we will try to construct a logical path between the ideas that helped einstein formulate general relativity and connect concepts at first glance so apart as geometry, curved space-times and gravitation. we have chosen to favour a constructive approach at the expense of lack of accuracy from a historical perspective. we hope to clarify the main concepts and principles involved in general relativity focusing mainly on its epistemological and philosophical implications.
Evaluation of the Benefits of Infiltration Pits on Soil Moisture in Semi-arid Zimbabwe
F.T. Mugabe
Journal of Agronomy , 2004,
Abstract: Rainfall is low and erratic in the semi-arid areas such that crop production fails in most years. Water harvesting techniques have been observed to harvest and concentrate rainwater and this results in increased soil moisture and yields. Most of this study has been done on in-field water harvesting techniques while there has not been any similar work to evaluate the benefits of in-contour water harvesting techniques on soil moisture and crop yields. Soil water storage was monitored above and below an infiltration pit over a season to identify differences in soil water storage of access tubes that are at different distances both above and below an infiltration pit. Soil moisture storage in the access tubes decreased from the infiltration pit both down slope and up slope. The difference in soil moisture between these access tubes increased during dry periods. The study highlights that the benefits of infiltration pits on soil moisture are realised during the dry spells because the water that is captured by the infiltration pits slowly seeps downwards to replenish soil moisture that is lost through evapotranspiration.
Mejoras del Aprendizaje y del Rendimiento de Grupos Reducidos de Estudiantes en una Asignatura de Proyectos de Ingeniería
Bogumil,F.T; Abad,F;
Formación universitaria , 2008, DOI: 10.4067/S0718-50062008000300003
Abstract: the characteristics, theoretical results and final conclusions of an experience for the improvement of the learning process and of its evaluation of a reduced group of students of a university course, is presented in this article. the experiment was done with an engineering project course at the technical university school of industrial engineers of terrassa, spain. the methodology considered the application of a questionnaire to evaluate the following aspects: individual work, group work, and preparation of oral presentations. during the academic course, several evaluations were done which allowed detecting students with low efficiency and making the necessary corrections to integrate them into the dynamics of the group. the results demonstrate that the new evaluation method allowed to achieve the objectives of motivation for the course, cohesion of the group and subject learning.
Effect of Landform and Irrigation Frequency on Cotton (Gossypium) Yield in Semi-arid Zimbabwe
F.T. Mugabe,F. Munyanyi
Journal of Biological Sciences , 2004,
Abstract: The effect of planting irrigated cotton on Tied Ridge (TR) and Flat (F) under three irrigation frequencies (75, 40 and 30% Depletion of Available Moisture, DAM) on yield and water use efficiency was studied at Chiredzi Research Station for two seasons 1990/91 and 1991/92. Growing cotton on tied ridges gave 19 and 35% more yield than on flat in the 1990/91 and 1991/92 seasons, respectively. More available moisture due to water collection on tied ridges as compared to flat was given as the reason for the yield increase. Yields were not affected by frequency of irrigation.
Ethical research as the target of animal extremism: an international problem
Michael Conn, P.;Rantin, F.T.;
Brazilian Journal of Medical and Biological Research , 2010, DOI: 10.1590/S0100-879X2010005000006
Abstract: animal extremism has been increasing worldwide; frequently researchers are the targets of actions by groups with extreme animal rights agendas. sometimes this targeting is violent and may involve assaults on family members or destruction of property. in this article, we summarize recent events and suggest steps that researchers can take to educate the public on the value of animal research both for people and animals
Reconstrucción del lóbulo auricular con colgajo bilobulado modificado
Fidalgo Rodríguez,F.T.;
Cirugía Plástica Ibero-Latinoamericana , 2012, DOI: 10.4321/S0376-78922012000100005
Abstract: earlobe absence may be due to congenital, oncologic or traumatic causes. this deformity sometimes constitutes an obvious facial deformity that warrants surgical correction. there are several techniques for reconstructing the earlobe, however, most of them require more than a onestage operation, may leave scars on the cheek or the preauricular or postauricular regions and sometimes require complementary skin grafts. it is difficult to reconstruct the natural and three-dimensional structure of the earlobe. in our practice we use a new type of local flap, with transposition and rotation techniques, based in a bilobed shape flap design.
On the Indeterminacy in Hardness of Shape Memory Alloys
FTCheng,
F.T.Cheng

材料科学技术学报 , 2004,
Abstract: The present communication addresses an interesting problem related to the indeterminacy in hardness of superelastic NiTi reported by Xu et al.1]. The origin of the indeterminacy is attributed to the inadequacy of the conventional Vickers hardness testing measurement which does not record elastic deformation, and thus the indeterminacy may be removed with suitable techniques. Concepts of hardness in relation to deformation are clarified. Recommendations for measuring the hardness of NiTi and other elastic-plastic materials are suggested, together with comments on the advantages and disadvantages of each of these methods.
Reflections on the Mechanism of Calcium Phosphate Nucleation on Titanium in Simulated Body Fluids
FTCheng,
F.T.Cheng

材料科学技术学报 , 2005,
Abstract: The results and main findings of studies reported in the literature in relation to the deposition of calcium phosphate on Ti in simulated body fluids are summarized. The effects of the surface hydroxyl groups and the sign of surface charge on the nucleation of calcium phosphate are reviewed. One major controversy among the conclusions of different studies is the order of adsorption of the calcium ions and the phosphate ions in the initial stage of immersion. A simple model based on the amphoteric nature of the hydroxyl groups on Ti is proposed in an attempt to delineate the nucleation process for calcium phosphate on Ti in simulated body fluids. HPO42- ions interact with the hydroxyl groups via ion exchange and/or electrostatic attraction, and Ca2 ions, via electrostatic attraction only. There is no preferential order of adsorption. Seemingly inconsistent results in different studies possibly arise from different prior treatments of the samples, which affect the adsorption properties.
Chieftaincy Titles In Yorubaland And Their Implication For Growth And Tolerance Among Christians And Muslims
Dr F.T. Lateju,Olusegun Oladosu
Lumina , 2012,
Abstract: This paper will examine comparatively the forms of chieftaincy title given among the three religious faiths in Yoruba land and how they have co-existed without necessarily jeopardizing their basic tenets of faith and practices. Yoruba people of South Western Nigeria have their own way of practicing their beliefs and the demands of the practice. The practices and beliefs held by Christians and Muslims today in Yoruba land in the area of chieftaincy titles have some identifiable variants. Christianity and Islam however did not come to the soil of Africa as a universal religion by which African may claim that it will solely represent the custom and cultural race of the people. The title of a chief which is one of the cultural titles in Yoruba land is associated with village heads, heads of cults or heads of lineages. These heads with a rank of chief perform traditional functions among the people that elect them. In this age of religious acculturation, where Christianity and Islam have taken a similar platform in the affairs of the people, the issues of traditional chieftaincy seem to them a form of tracking the concentration of their members in the act of discharging their spiritual responsibilities. In this case, they prefer to adopt a better mode of disengaging the spiritual conflict of their members for them to remain faithfully committed. Functions of the chieftaincy include addressing any issue in the administration of justice in relation to their office, seeing to the welfare of their communities, monitoring socio-economic and promoting religious tenet as it relates to their convictions. Subsequently, some sects among Christian and Islamic groups therefore created a dimension of title that fits into their faith and is traditionally oriented.
第1页/共243156条
每页显示


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.