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Publicações

2014

STOVEPipe: Observable Access Control of User Data for Untrusted Applications on Mobile Devices

Autores
Tan, J; Drolia, U; Martins, R; Gandhi, R; Narasimhan, P;

Publicação
IEEE 6th International Conference on Cloud Computing Technology and Science, CloudCom 2014, Singapore, December 15-18, 2014

Abstract
The rapid growth in mobile devices will give rise to the trend of the leasing out of compute and data resources on mobile devices to third-parties for applications to be run on multiple mobile devices. However, these third-party applications running on leased mobile devices are typically written by unknown entities, and cannot be trusted by mobile device owners. Current mobile device platforms (e.g. Android) have permissions and access control systems designed for mobile apps that are written by reputable developers and vetted by authoritative app stores, and they are not suitable for untrusted apps. We propose STOVEPipe, an observable access control system for user data on mobile devices for untrusted third-party applications. STOVEPipe ensures that untrusted code is isolated and cannot directly access system data, and performs all data accesses on behalf of untrusted apps. This enables STOVEPipe to observe all data accessed by untrusted apps, implement content-based access control, perform accounting and auditing on accessed data easily, and perform privacy-preserving data transformations. © 2014 IEEE.

2014

Risk-Constrained Offering Strategy of Wind Power Producers Considering Intraday Demand Response Exchange

Autores
Heydarian Forushani, E; Moghaddam, MP; Sheikh El Eslami, MK; Shafie khah, M; Catalao, JPS;

Publicação
IEEE TRANSACTIONS ON SUSTAINABLE ENERGY

Abstract
This paper proposes a comprehensive stochastic decision making model for wind power producers' (WPPs) participation in a competitive market. The presented model incorporates three trading floors: 1) day-ahead; 2) intraday; and 3) balancing markets. An efficient integration of intraday markets allows market players to react to the latest information (e. g., more accurate wind forecast). Creating a platform that allows demand response resources (DRRs) to contribute to the intraday markets improves both WPP's business and power system flexibility. In this context, providing an intraday demand response exchange (IDRX) market for trading demand response (DR) between DR providers and DR users (e. g., WPPs) is proposed. The problem uncertainties, such as wind power and market prices, are considered using a scenario-based approach. Moreover, an appropriate risk measurement, conditional value-at-risk (CVaR), is incorporated with the model. Numerical results illustrate that utilizing DR to compensate wind generation imbalances can increase WPP's profit and reduce the related risks.

2014

Influence of consumer purchasing behaviour on the production planning of perishable food

Autores
Amorim, P; Costa, AM; Almada Lobo, B;

Publicação
OR SPECTRUM

Abstract
This paper addresses the impact of consumer purchasing behaviour on the production planning of perishable food products for companies operating in the fast moving consumer goods using direct store delivery. The research presented here builds on previous marketing studies related to the effects of expiry dates in order to derive mathematical formulae, which express the age dependent demand for different categories of perishable products. These demand expressions take into account both customer willingness to pay and product quality risk. The paper presents deterministic and stochastic production planning models, which incorporate the customer's eagerness to pick up the fresher products available. Results indicate that model approximations neglecting the fact that customers pick up the fresher products or considering that all products have the same product quality risk have a reduced impact on profit losses. On the other hand, not considering the decreasing customer willingness to pay has an important impact both on the profit losses and on the amount of spoiled products.

2014

A New Cavity Ring-Down Topology for Remote Sensing

Autores
Passos, DJ; Silva, SO; Marques, MB; Frazao, O;

Publicação
2014 THIRD MEDITERRANEAN PHOTONICS CONFERENCE

Abstract
A new, fiber-based, cavity ring-down topology is presented which enables the application of the cavity ring-down technique to remote sensing, by the use of a large cavity ring and an optical circulator. For a proof of concept a 1.5 km ring is assembled and a taper is used as a sensing head for measuring displacement. The cavity ring-down technique is seen to hold some potential for remote sensing through its implementation on optical fibers.

2014

Effects of experience on the dimensions of intensity, direction and frequency of the competitive anxiety and self-confidence: A study in athletes of individual and team sports [Efeitos da experiência nas dimensões de intensidade, direção e frequência da ansiedade e autoconfiança competitiva: Um estudo em atletas de desportos individuais e coletivos]

Autores
Fernandes, MG; Nunes, SAN; Raposo, JV; Fernandes, HM;

Publicação
Motricidade

Abstract
The present study had the following objectives: i) to examine the inter-scale correlations between the three dimensions of responses (intensity, direction and frequency) of the CSAI-2R and its relationship with competitive experience, and ii) evaluate the effect of competitive experience anxiety (cognitive and somatic) and self-confidence in the total sample and for different types of modalities (individual vs. team). The sample consisted of 267 athletes (196 male and 71 female), of different sports, aged be-tween 18 and 40 years (M = 24.30, SD = 5.62). Athletes completed the Brazilian version of the CSAI-2, which included the addition of the dimensions of direction and frequency response. Spearman test and Manova were used for the data analysis. Overall, it was found that the competitive experience has a high multivariate and significant effect on the dimensions of competitive anxiety. Both individual and team athletes with low competitive experience showed a trend to report lower levels of self-confidence intensity, compared to counterparts with high competitive experience. These results were discussed in view of the theoretic framework and practical implications planning Sport Psychology intervention programs in local athletes with different backgrounds. Copyright © 2014 Fundação Técnica e Científica do Desporto.

2014

A Safe Approximation for Kolmogorov Complexity

Autores
Bloem, P; Mota, F; de Rooij, S; Antunes, L; Adriaans, P;

Publicação
Algorithmic Learning Theory (ALT 2014)

Abstract
Kolmogorov complexity (K) is an incomputable function. It can be approximated from above but not to arbitrary given precision and it cannot be approximated from below. By restricting the source of the data to a specific model class, we can construct a computable function (kappa) over bar to approximate K in a probabilistic sense: the probability that the error is greater than kappa decays exponentially with kappa. We apply the same method to the normalized information distance (NID) and discuss conditions that affect the safety of the approximation.

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