Repositório Institucional da Universidade de Aveiro
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Adjustable Electrical Dispersion Compensation in a 40-Gb/s Optical Single Sideband System
No full textThe efficiency of an adjustable electrical dispersion compensator (AEDC) in a 40-Gb/s optical single sideband system is investigated experimentally. The AEDC is implemented using a developed monolithic feed-forward equalizer whose performance can be optimized by adjusting the tap weights. Specifically, the AEDC contribution to the system performance improvement is achieved by synthesizing a suitable transfer function that shows group delay dependency on the frequency opposite to that of the fiber. Group velocity dispersions up to 272 ps/nm are experimentally obtained with a power penalty of less than 4 dB relative to the back-to-back situation without equalization
Investor sentiment and market reaction: evidence on 2010 FIFA World Cup
No full textThe purpose of this study is to examine whether investor sentiment influences the stock price reaction to football matches results, giving some contribute to the behaviour finance, or if investors react in a rational way, giving evidence of standard finance. To proxy for investor sentiment, we analyse the 2010 FIFA World Cup of South Africa.
Globally, the study provides no evidence of a direct relationship between games results and the subsequent market reaction, not documenting a change in investor mood caused by soccer games outcomes.
This paper contributes to the recent literature on the asset pricing impact of behaviour biases. The global results are more in line with standard finance than on behaviour finance, suggesting that stock prices are not influenced by economically-neutral events that can affect the investor sentiment, and, consequently, the stock prices
Numerical solution of curved pipes submitted to in-plane loading conditions
No full textThe paper describes numerical solutions based in the combination of polynomial/trigonometric shape functions to define the stress and deformation field of curved pipes under bending.(Not applicable
Competitiveness factors: a portuguese perspective
No full textThis book aims at contributing to the on-going discussion about economies’ performance and firm competitiveness by looking at what the contemporary and emerging factors of firm competitiveness are within the present setting characterized by globalization, the knowledge-based economy and technological and climate change. It looks at what factors are critical for competitiveness, focussing on a Portuguese perspective within the EU context. While an adequate economic and institutional framework in the EU and its member states (an issue addressed within the Lisbon Agenda) importantly conditions firms’ competitiveness, this book primarily deals with the firm level and considers how firms may transform the challenges and constraints brought about by a rapidly changing business environment into economic opportunity. To find out what provides a decisive edge for companies on the global market one needs to analyze the leading competitiveness factors today, but also try to understand what those competitiveness factors will or could look like within the medium and longer term.
The book brings together a range of contributions combining illustrative data and theory on the subject of competitiveness from contributors with different backgrounds, notably from business, economics and engineering, in the follow-up of the enterprise of the future project at DEGEI, University of Aveiro. llle book is composed of two parts. Part I addresses competitiveness facro rs in the
co ntemporary eco nomy. In mday's world firms need to plan ahead and innovate in the
face of an uncenain business environment, they need to be COSt effici ent in production
and generally realize COSt effi ciencies and innovation ever more within a cluster and
synergy perspective.
-nle second part of the book discusses competiti veness with a view to the challenges
and indeed opportunities arising from globalization . the knowledge economy and
from technological and climate change. Issues addressed regard the internationalisation
of the va lu e chain. the role of public institutions for innovation and firm
competitiveness, and effi ciency and innovation in energy as a new and emerging
competiti veness factor
A new approach for time-triggered phase in the FTT-CAN protocol: a case study in an automotive system
No full textImportant researches have presented different
approaches in the real-time embedded communication domain
aiming to cover the growing demands of performance,
predictability and reliability of emerging applications. Such
requirements involve low latency, reduced jitter, time composability,
fault-tolerance and finally, support for future extensions.
In agreement, the FTT (Flexible Time-Triggered) model is
an approach which aiming to provide flexibility on the timetriggered
traffic together with timeliness, differently of others
approaches. This paper present a new and enhanced FTT model
to improve some drawbacks in the time-triggered message
traffic and time-triggered task execution. Some experimental
results has been performed using a FTT-CAN implementation
over an embedded linux with RTAI extension
Rigidity of abnormal extrema in nonlinear programming problems with equality and inequality constraints
No full textOptimality conditions for nonlinear problems with equality and inequality constraints are considered. In the case when
no constraint qualification (or regularity) is assumed, the Lagrange multiplier corresponding to the objective function can
vanish in first order necessary optimality conditions given by Fritz John and the corresponding extremum is called abnormal.
In the paper we consider second order sufficient optimality conditions that guarantee the rigidity of abnormal extrema
(i.e. their isolatedness in the admissible sets)
On the minimum and maximum averaged resistance problem of moving bodies
No full textA body moving in a rarefied medium of point fixed particles is considered. The center of mass of the body moves with a constant speed, and, moreover, the body executes slow rotational motions. The resistance force of the medium to the body's motion is defined. The concept of a rough body is introduced, and it is proved that the ratio between the resistance of the rough body and that of the smooth body corresponding to it lies in the limits from 0.969 up to 2. © 2007 Springer Science+Business Media, Inc
A influência do tipo de haste do componente femoral na revisão da ATJ: Analise pelo método dos elementos finitos
No full textEste artigo tem como objectivo dar resposta sobre a capacidade de transferência de carga, assim como
a estabilidade proporcionada pela utilização das hastes (cimentada ou press-fit) no componente
femoral aquando da cirurgia de revisão da artroplastia total do joelho. A análise pelo método dos
elementos permitiu determinar a quantidade de carga transferida pelos diferentes tipos de haste para a
zona proximal do fémur assim como a estabilidade entre o componente femoral e o osso cortical,
assim como na interface osso-cimento. Procurou-se igualmente correlacionar qualitativamente alguns
dos resultados obtidos com alguns factos clínicos
The propagation of axisymmetric transverse waves along a thin-walled cylindrical pipe
No full textThis work involves the numerical and experimental study of the propagation of axisymmetric waves along a pipe submitted to a sudden and uniformly applied radial force. In an experimental procedure, this kind of loading may result from the detonation of an explosive inside the pipe. Both ends were left open, so that only radial loads could be achieved in the experiment. A value for the axial propagation of the generated transverse wave train was determined and compared with the numerical analysis
Numerical analysis of piping elbows for in-plane bending and internal pressure
No full textThis work presents the development of two different finite piping elbow elements with two nodal tubular sections for
mechanical analysis. The formulation is based on thin shell displacement theory, where the displacement is based on
high-order polynomial or trigonometric functions for rigid-beam displacement, and uses Fourier series to model warping
and ovalization phenomena of cross-tubular section. To model the internal pressure effect an additional formulation is used
in the elementary stiffness matrix definition. Elbows attached to nozzle or straight pipes produce a stiffening effect due to the restraint
of ovalization provided by the adjacent components. When submitted to any efforts, the excessive oval shape may reduce the
structural resistance and can lead to structural collapse. For design tubular systems it is also important to consider the internal-pressure
effect, given its effect on the reduction of the pipe flexibility. Some conclusions and examples are compared with results produced by other authors