Browsing by Issue Date, starting with "2011-04"
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- Using social networks theory as a complementary perspective to the study of organizational changePublication . Ferreira, Manuel Portugal; Armagau, SunguThis paper contributes to the literature on organizational change by examining organizations as social entities embedded in inter-organizational networks. In contrast with extant research that focuses on macro environmental and internal factors to explain organizational change, we put forth the social network surrounding the firm as a major driver of any change process. Specifically, we examine organizational change as driven by the organizations’ positions and relations in an interorganizational network, and advance a set of theory driven propositions on innovation, imitation, inertia, structural equivalence and structural positioning. Our conceptual discussion demonstrates that inter-organizational networks are important in complementing the macroenvironment and internal organizational factors for the study of organizational changes. We conclude with a discussion on normative implications for organizations and avenues for future research.
- Blind men and the elephant : how to cope with european mobility finantial cutbacksPublication . Boa-Ventura, Ana Cecília; Silva, José ManuelDonald Puchala's metaphor of the blind men and the elephant is used to stress what the authors consider to be the current situation with the financial aid cutbacks from the European Commission: each of one of the member states is able to see only part of the problem and cannot see the whole picture. How can we cope with the consequences of having less students in mobility programs and more strategies to increase mobility in our own universities? We will share with you (1) how Portugal is trying to solve this problem, (2) the data from the past 2 years from our National Agency’s new policies and (3) the results of a case study of the Polytechnic Institute of Leiria, regarding incoming and outgoing Erasmus students for the 2010/2011 academic year.
- A 130 nm CMOS LNA for 30 GHz applicationsPublication . Ribeiro, R.; Moreira Mendes, Luís Miguel; Vaz, J. C.; Rosario, M. J.; Freire, J. C.This paper presents the design of a 30 GHz low noise amplifier in a 130 nm CMOS technology. The amplifier is based on a cascode topology. The circuit uses autotransformers in the input and output matching networks. This design approach eliminates the necessity of the use of source degeneration and allows obtaining an ultra compact LNA. The amplifier presents a forward gain (S21) of 7.4 dB at 30 GHz with a bandwidth of 10 GHz, input and output VSWRs better than 1.22:1 and a noise figure of 3.7 dB. The LNA is unconditionally stable and consumes only 7 mW when supplied with 1.2 V. The amplifier fits an area of 0.08 mm2, which is one of the smallest areas reported.
- Computational complexity reduction methods for multiscale recurrent pattern algorithmsPublication . Francisco, Nelson C.; M. M. Rodrigues, Nuno; Silva, Eduardo A. B. da; Carvalho, Murilo B. de; Faria, SergioThe Multidimensional Multiscale Parser algorithm was originally proposed as a generic lossy data compression algorithm. An high degree of adaptivity and versatility allowed it to outperform state-of-the-art transform-based compression methods for a wide range of applications, from still images, compound documents, or even ECG's, just to name a few. However, as other pattern matching algorithms, it presents a high computational complexity. In this paper, we investigated several techniques that allowed to considerably reduce both the encoder's and the decoder's computational complexity, with marginal R-D performance losses. The most important reduction was achieved on the decoder, that reduced up to 95% the time required by the previous method. These improvements contribute to affirm MMP as an alternative to traditional transform-based encoders, approaching its computational complexity with that of transform-based algorithms.
- Development and performance analysis of a real time high-resolution channel sounder - IF stagePublication . Ferreira, D.; Caldeirinha, RafaelThis paper presents an intermediate frequency (IF) stage of a swept time delayed cross-correlation (STDCC) channel sounder. The proposed topology employs the real-time sliding correlation technique of pseudo-random (PN) sequences, enabling amplitude and Doppler spectrum measurements and analysis of multipath components. It makes use of recent technologies, specifically in the generation and transmission of PN sequences, which allows for an easy adjustment of the main specifications of the sounder. The system presented here has been tested and validated by using a PN sequence at 1GHz chip rate, which allows for a time-delay resolution of consecutive multipath components of 2ns. The dynamic range at the IF stage's input was measured to be around 40 to 50 dB. The results presented are also compared with the VNA frequency sweep method.
- Vítimas mortais em acidentes de viação em Portugal continental : uma abordagem através da Análise Espectral SingularPublication . Sebastião, Fernando; Oliveira, IreneUma das preocupações da política nacional, nas últimas décadas, tem sido a segurança rodoviária, e em particular a intenção de reduzir os níveis de sinistralidade. Um dos agentes envolventes é a mortalidade resultante dos acidentes de viação. Este trabalho tem como objectivo explorar os dados mensais do número de vítimas mortais em acidentes de viação ocorridos em Portugal Continental, durante os últimos doze anos, através da Análise Espectral Singular.