Catálogo de publicaciones - libros

Security policies form a collection of access restrictions on objects and resources. In this paper, we introduce an access control model with constraints that are common in typical information systems. This access control model is based on the role-based access control policy. It is modified to represent object classes and their hierarchies. The formalization of the proposed policy and constraints is performed using a logical approach based on description logics. Several access control constraints are discussed. The capability of the proposed model to formalize object-based constraints is demonstrated.

Most of the existing IDS use all the features in network packet to evaluate and look for known intrusive patterns. Some of these features are irrelevant and redundant. The drawback to this approach is a lengthy detection process. In real-time environment this may degrade the performance of an IDS. Thus, feature selection is required to address this issue. In this paper, we use wrapper approach where we integrate Rough Set and Particle Swarm to form a 2-tier structure of feature selection process. Experimental results show that feature subset proposed by Rough-DPSO gives better representation of data and they are robust.

Simulating fluid flow in geological formations requires mesh generation, lithology mapping to the cells, and computing geometric properties such as normal vectors and volume of cells. The purpose of this research work is to compute and process the geometrical information required for performing numerical simulations in geological formations. We present algebraic techniques, named Transfinite Interpolation, for mesh generation. Various transfinite interpolation techniques are derived from 1D projection operators. Many geological formations such as the Utsira formation and the Snøhvit gas field can be divided into layers or blocks based on the geometrical or lithological properties of the layers. We present the concept of block structured mesh generation for handling such formations.

In any parallel programming language; collective communication operations involve more than one thread/process and act on multiple streams of data. The language’s API provides both algorithmic and run-time system support to optimize the performance of these operations. Some developers, however, choose to play clever and start from the language’s primitive operations and write their own versions of the collective operations. The question that always pops up: Are these developers wise? In this paper, we check the case of UPC (Universal Parallel C) and prove that in some circumstances, it is wiser for developers to optimize starting from UPC’s primitive operations. In our testing we found out that optimization using primitive UPC operations by the developers can have better performance than readily available UPC’s collective operations. In this paper, we pin point specific optimizations at both the algorithmic and the runtime support levels that developers could use to uncover missed optimization opportunities. We also propose a novel approach to implementing UPC collective operations across clusters. Under this methodology, performance-critical components are moved close to the network. We argue that this provide unique advantages for performance improvement.

Support vector machines (SVM) and rough sets theory (RST) are two emerging techniques in data analysis. The RST can deal with vague data and remove redundant attributes without losing any information of the data; and SVM has powerful classification ability. In this study, the RST is employed to reduce data attributes. Then, the reduced attributes are used by the SVM model for classification. An example of diesel engine diagnosis in the literature is used to demonstrate the diagnosis ability of the proposed RSSVM (rough set theory with support vector machines) model. In terms of classification accuracy and efficiency, experimental outcomes show that the RSSVM model can provide better diagnosis results than those obtained by the directed acyclic graph support vector machine (DAGSVM) model.

A style dress outlet usually purchases products from multiple suppliers with different cost, quality and selling price. It is assumed that some suppliers will sell their goods to the buyer outright, while some other suppliers will offer return policy for items unsold. In the latter case, the supplier buys back from the buyer the unsold items at the end of the selling season. The purpose of this study is to enable the buyer to develop a supplier selection and replenishment policy subject to limited budget. A minimal service level and uncertain market are assumed as well. Genetic algorithm (GA) is used to solve the problem.

Controlling the amount of water in maintaining lawn health and beauty is a main topic in horticulture. A reliable controller is needed to control the amount of water to disperse as to ensure the soil has enough moisture adequacy level. This research explores the use of fuzzy logic for the controlling of water dispersal. The performances of fuzzy water dispersal controller (FuziWDC) was measured based on a significant set of common Bermuda turfgrass. An improved Sugeno inferencing for the task of water dispersal controller is presented that considered both evapotranspiration (ET), tensiometer variable as opposed to the earlier work. A comparison of the output is being performed to evaluate Sugeno with conventional system. The result shows FuziWDC has performed better than the conventional technique based on the lower annual average water usage for the whole year recorded.

Unforgeabilty is a primitive property of a secure digital signature. As two extensions of digital signature, signcryption and certificateles signature play an important role in the sensitive transmission. In this work, we analyze the security of two signature schemes, one is the certificateless signature scheme[17] which was proposed by Gorantla in CIS 2005, the other is an efficient short signcryption scheme[8] which was proposed by Ma in Inscrypto 2006. Then, we show that the two schemes were insecure. In Ma ’s scheme, if the recipient is dishonest, then he can produce any forgery on an arbitrary message and convince the trusted third party that the forgeable signcrytion comes from the signer. While, in Gorantla ’s scheme, any one can forge a signature on an arbitrary message in the name of the others. Finally, we give the corresponding improved scheme, respectively.

Information aggregation is an important operation in wireless sensor networks executed for the purpose of monitoring and reporting of the environmental data. Due to the performance constraints of sensor nodes the in-network form of the aggregation is especially attractive since it allows to save expensive resources during the frequent network queries. Easy accessibility of networks and nodes and almost no physical protection against corruptions arise high challenges on the security of the aggregation process. Especially, protection against attacks aiming to falsify the aggregated result is considered to be of prime importance.

In this paper we propose a novel security model for the aggregation process based on the well-established cryptographic techniques, focusing on the scenario with the single aggregator node. In order to show soundness and feasibility of our definitions we describe a practical approach that achieves security against node corruptions during the aggregation process in a provable cryptographic way based solely on the symmetric cryptographic primitives. To the best of our knowledge this is the first paper which aims to combine the paradigm of in the cryptographic sense with the task of information aggregation in WSNs.

Ubiquitous multimedia services are emerging to be available at anytime and anywhere using a variety of computing devices. In this paper, we propose a low-complexity unequal loss protection (ULP) scheme for real-time transmission of video over ubiquitous networks. By using the unequal importance existing in different levels of hierarchical structure for video coding, the assignment algorithm for forward error correction (FEC) of packets with low complexity is proposed. The developed algorithm for efficient FEC assignment is based on a simple closed form solution for the estimation of the expected length of error propagation. The closed form solution represents well the weighted temporal propagation effect of packet loss. The proposed algorithm provides a simple and effective FEC assignment with much reduced computational complexity. Simulation results show that the performance is better while the computational complexity is very low compared to the previous ULP scheme. Hence the proposed FEC assignment scheme can be used efficiently for real-time video applications over ubiquitous networks.