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991.
Diaz Zayas Almudena Merino Gomez Pedro Rivas Tocado Francisco 《Pervasive Computing, IEEE》2010,9(1):54-61
The SymPA (Symbian Protocol Analyzer) tool correlates traffic information, radio-access-technology measurements, and location data to help developers evaluate mobile applications in the field. 相似文献
992.
This work presents a multi-objective genetic algorithm to solve route planning problem for multiple autonomous underwater vehicles (AUVs) for interdisciplinary coastal research. AUVs are mobile unmanned platforms that carry their own energy and are able to move themselves in the water without intervention from an external operator. Using AUVs one can provide high-quality measurements of physical properties of effluent plumes in a very effective manner under real oceanic conditions. The AUV's route planning problem is a combinatorial optimization problem, where the vehicles must travel through a three-dimensional irregular space with all dimensions known. Therefore, minimization of the total travel distance while considering the maximum number of water samples is the main objective. Besides the AUV kinematics restrictions other considerations must be taken into account to the problem, like the ocean currents. The practical applications of this approach are the environmental monitoring missions which typically require the sampling of a volume of water with non-trivial geometry for which parallel line sweeping might be a costly solution. Some real-life test problems and related solutions are presented. 相似文献
993.
In this work, we introduce a Model Driven Development method for developing context-aware pervasive systems. This method allows us to specify a context-aware pervasive system at a high level of abstraction by means of a set of models, which describes both the system functionality and the context information. From these models, an automated code generation strategy is applied. This strategy allows us to generate the system Java code that provides the system functionality and as well as an OWL specification that represents the context information and allows us to manage this information without additional burden. Furthermore, this specification is used by a reasoner at runtime to infer context knowledge that is not directly observable, and it is also used by machine learning algorithms to give support to the system adaptation according to the context information. 相似文献
994.
Asier Ibeas Manuel de la Sen Pedro Balaguer Ramón Vilanova Carles Pedret 《International Journal of Control, Automation and Systems》2010,8(4):707-719
In this paper, a digital implementation of an inverse-model based control scheme is proposed using Generalised Sampling and Hold Functions. The implementation of the controller using this kind of holds allows overcoming the difficulties related to the presence of unstable zeros in the continuous-time model and the usual appearance of unstable discretisation zeros in the discrete model when a ZOH is applied. The Generalised Sampling and Hold Functions allows obtaining a discrete model of the plant with all its zeros stable which allows realizing an exact inverse model of the plant in comparison to the use of a classical ZOH which only allows, in general, an approximate inversion of the plant. The proposed approach is then extended to the adaptive case where the stability and tracking properties of the general scheme are fully proved. Simulation examples showing the scope and application of the method are also presented. 相似文献
995.
Davide Figo Pedro C. Diniz Diogo R. Ferreira João M. P. Cardoso 《Personal and Ubiquitous Computing》2010,14(7):645-662
The ubiquity of communication devices such as smartphones has led to the emergence of context-aware services that are able
to respond to specific user activities or contexts. These services allow communication providers to develop new, added-value
services for a wide range of applications such as social networking, elderly care and near-emergency early warning systems.
At the core of these services is the ability to detect specific physical settings or the context a user is in, using either
internal or external sensors. For example, using built-in accelerometers, it is possible to determine whether a user is walking
or running at a specific time of day. By correlating this knowledge with GPS data, it is possible to provide specific information
services to users with similar daily routines. This article presents a survey of the techniques for extracting this activity
information from raw accelerometer data. The techniques that can be implemented in mobile devices range from classical signal
processing techniques such as FFT to contemporary string-based methods. We present experimental results to compare and evaluate
the accuracy of the various techniques using real data sets collected from daily activities. 相似文献
996.
Rodríguez Erasmo Sánchez Inés Duque Nicolás Arboleda Pedro Vega Carolina Zamora David López Patricia Kaune Alexander Werner Micha García Camila Burke Sophia 《Water Resources Management》2020,34(7):2179-2199
Water Resources Management - Reanalysis and earth observation data have enormous potential to support water resources management, particularly in river basins where data availability is poor or... 相似文献
997.
Pedro Arsnio Patricia María Rodríguez‐Gonzlez Ivan Bernez Filipe S. Dias Miguel N. Bugalho Simon Dufour 《河流研究与利用》2020,36(6):907-920
Social‐ecological contexts are key to the success of ecological restoration projects. The ecological quality of restoration efforts, however, may not be fully evident to stakeholders, particularly if the desired aesthetic experience is not delivered. Aesthetically pleasing landscapes are more highly appreciated and tend to be better protected than less appealing landscapes, regardless of their ecological value. Positive public perception of restoration actions may therefore facilitate stakeholder involvement and catalyse recognition of ecological improvement. Here we aim to contrast aesthetical perception and ecological condition in headwater river reaches restored through passive ecological restoration in study areas in Portugal (Alentejo) and France (Normandy). We recorded structural and functional indicators of riparian vegetation to monitor the ecological condition of study sites along a passive restoration trajectory. Aesthetical perception indicators were assessed through stakeholder inquiries developed under a semantic differential approach. We analysed perception responses to changes in the riparian ecosystems resulting from passive ecological restoration across different geographical contexts and social groups. The analysed social groups comprised stakeholders (environmental managers and landowners) and university students (landscape architecture and geography students). Results indicate that (a) visual preferences often do not reflect changes in ecological condition, (b) perception of the restoration process is strongly context dependent, and (c) experience and cultural background affect perception of ecological condition across the different social groups analysed. Clear identification of relevant stakeholder groups (those interested in or directly affected by restoration), effective communication, and stakeholder engagement are therefore essential for assuring the success of river restoration projects. 相似文献
998.
Stability of gaseous samples is a major concern when dealing with odours and airborne pollutants sampling. In terms of odours, the representativeness of the sample can be very seriously compromised, despite the rigorous application of the maximum storage time established by EN-13725. The present paper is focused on the use of the cryo-condensation technique (Cryocore) for time-weighted-average (TWA) sampling in waste water treatment plants (WWTPs), with the aim of comparing the values of TWA odour and H(2)S concentration when using the Cryocore system and other well established sampling methods, such as those described in EN-13725 and passive sampling. The study showed comparable results when comparing all the methodologies tested. 相似文献
999.
Pedro Lara Fábio Borges Renato Portugal Nadia Nedjah 《Journal of Computer and System Sciences》2012,78(2):575-582
The modular exponentiation operation of the current algorithms for asymmetric cryptography is the most expensive part in terms of computational cost. The RSA algorithm, for example, uses the modular exponentiation algorithm in encryption and decryption procedure. Thus, the overall performance of those asymmetric cryptosystems depends heavily on the performance of the specific algorithm used for modular exponentiation. This work proposes new parallel algorithms to perform this arithmetical operation and determines the optimal number of processors that yields the greatest speedup. The optimal number is obtained by balancing the processing load evenly among the processors. Practical implementations are also performed to evaluate the theoretical proposals. 相似文献
1000.
The phenomenon of birefringence may be observed when light arrives at an anisotropic crystal surface and refracts through
it, causing the incident light ray to split into two rays; these become polarized in mutually orthogonal directions, and two
images are formed. The principal goal of this paper is the study of the directional issues involved in the behavior of light
when refracting through a homogeneous, non-participating medium, including both isotropic and anisotropic media (uniaxial
and, for the first time, biaxial). The paper focuses on formulating and solving the non-linear algebraic system that is obtained
when the refraction process is simulated using the geometric model of Huygens. The main contribution focuses on the case of
biaxial media. In the case of uniaxial media, we rely on symbolic calculus techniques to formulate and solve the problem. 相似文献