University of Piraeus

About: University of Piraeus is a education organization based out in Piraeus, Attiki, Greece. It is known for research contribution in the topics: Context (language use) & Computer science. The organization has 1731 authors who have published 6209 publications receiving 106699 citations.

Developing full-spectrum innovation capability for survival and success in the global economy

Abstract: In the last two decades the competitive landscape for many organisations has been changing rapidly in complex and unpredictable ways. As a result, their ability to survive in the global economy often takes priority over the industrial era goal of profit maximisation. This is particularly obvious now, following the onset of the current global economic crisis, the biggest since the Great Depression of the 1930s. Full-spectrum innovation capability refers to an organisation's ability to create value derived not only from new products and services for customers, but also from changes in its business model, in its culture and in the distribution of power for decision-making. The proposed approach involves pursuing innovations (1) horizontally, working from customer needs backwards along successive stages of a firm's value chain; and (2) vertically, at successively deeper levels of communications and decision-making processes, based on challenging the assumptions underlying the present business model. The purpo...

A Stochastic Beamforming Algorithm for ESPAR Antennas

Abstract: Beamforming capabilities of ESPAR antenna structures have attracted considerable attention in recent literature. In this letter, we consider a different beamforming approach, presenting an efficient optimization algorithm which enables such antennas to create desired transmit radiation patterns in real time, rather than patterns aiming at signal to interference ratio maximization. The proposed algorithm may be used in any beamforming, diversity or multiuser system. In order to demonstrate the algorithm's efficiency, we investigate a scenario with mobile handsets equipped with ESPAR antennas, considering a beamspace multiple inputmultiple output architecture. It is shown that the algorithm may enforce even cost and size sensitive devices to efficiently operate in closed loop communication environments.

A study of the build-time estimation problem for Stereolithography systems

Abstract: In this paper the problem of build-time estimation for Stereolithography systems is examined. Experimental results from various case studies indicate that the accuracy of estimation greatly depends on the type of part geometry representation processed and the uncontrolled laser power fluctuations. It is shown that estimation based on sliced (CLI) representation can be extremely accurate, assuming that the average laser power during fabrication can be predicted. On the other hand, estimations based on tessellated (STL) representation, although not so accurate, satisfy the accuracy requirements imposed at early stages of the Stereolithography process, where no slice data are available. As part of this study, build-time itself is also analyzed and factors affecting it are identified and investigated experimentally. Results indicate that hatching time depends not only on the hatching distance and speed, as originally assumed, but also on the number of hatching vectors employed.