136 research outputs found
Acceso abierto a las publicaciones científicas : definición, recursos, copyright e impacto
Publicado en: El Profesional de la Información 15(4): pp. 255-66 (2005)El movimiento a favor del acceso abierto a las publicaciones científicas (Open access) cada vez tiene más adeptos y apoyo, tanto institucional como de los miembros de la comunidad científica, y también son numerosas las manifestaciones e iniciativas en torno al mismo. Este artículo analiza el significado de Open access o Acceso abierto a las publicaciones científicas a través de internet de acuerdo con las declaraciones de Budapest, Bethesda y Berlín. Se revisan algunos aspectos relacionados con el impacto de las revistas OA y las implicaciones de la cesión de derechos de copyright en el acceso abierto. Por último se evalúan las perspectivas de futuro del acceso en abierto desde el punto de vista de las políticas.Peer reviewe
Robust Flows over Time: Models and Complexity Results
We study dynamic network flows with uncertain input data under a robust
optimization perspective. In the dynamic maximum flow problem, the goal is to
maximize the flow reaching the sink within a given time horizon , while flow
requires a certain travel time to traverse an edge.
In our setting, we account for uncertain travel times of flow. We investigate
maximum flows over time under the assumption that at most travel times
may be prolonged simultaneously due to delay. We develop and study a
mathematical model for this problem. As the dynamic robust flow problem
generalizes the static version, it is NP-hard to compute an optimal flow.
However, our dynamic version is considerably more complex than the static
version. We show that it is NP-hard to verify feasibility of a given candidate
solution. Furthermore, we investigate temporally repeated flows and show that
in contrast to the non-robust case (that is, without uncertainties) they no
longer provide optimal solutions for the robust problem, but rather yield a
worst case optimality gap of at least . We finally show that the optimality
gap is at most , where and are newly introduced
instance characteristics and provide a matching lower bound instance with
optimality gap and . The results obtained in
this paper yield a first step towards understanding robust dynamic flow
problems with uncertain travel times
Pre-processing for Triangulation of Probabilistic Networks
The currently most efficient algorithm for inference with a probabilistic
network builds upon a triangulation of a network's graph. In this paper, we
show that pre-processing can help in finding good triangulations
forprobabilistic networks, that is, triangulations with a minimal maximum
clique size. We provide a set of rules for stepwise reducing a graph, without
losing optimality. This reduction allows us to solve the triangulation problem
on a smaller graph. From the smaller graph's triangulation, a triangulation of
the original graph is obtained by reversing the reduction steps. Our
experimental results show that the graphs of some well-known real-life
probabilistic networks can be triangulated optimally just by preprocessing; for
other networks, huge reductions in their graph's size are obtained.Comment: Appears in Proceedings of the Seventeenth Conference on Uncertainty
in Artificial Intelligence (UAI2001
Обоснование параметров рамно-анкерной крепи протяженных горных выработок с учетом закономерностей деформирования системы «крепь – массив»
Проблемы сохранности личных данных сотрудников в организации
Каждый человек обладает личной информацией, который в праве, распоряжаться только он сам. К персональным данным человека относится не только рост и вес, но и данные о его рождении, место проживания, образование, серия и номер паспорта, которые в современном обществе от нас требуют в каждой организации. А на сколько, защищены наши персональные данные, при передаче их иному лицу? Кто несет ответственность за безопасное хранение данной информации
Recoverable Robust Knapsacks: the Discrete Scenario Case
Admission control problems have been studied extensively in the past. In a typical setting, resources like bandwidth have to be distributed to the different customers according to their demands maximizing the profit of the company. Yet, in real-world applications those demands are deviating and in order to satisfy their service requirements often a robust approach is chosen wasting benefits for the company. Our model overcomes this problem by allowing a limited recovery of a previously fixed assignment as soon as the data are known by violating at most k service promises and serving up to l new customers. Applying this approaches to the call admission problem on a single link of a telecommunication network leads to a recoverable robust version of the knapsack problem
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