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Evaluation of the Use of Guard Nodes for Securing the Routing in VANETs
Juan A. Martinez,Daniel Vigueras,Francisco J. Ros,Pedro M. Ruiz 한국통신학회 2013 Journal of communications and networks Vol.15 No.2
We address the problem of effective vehicular routing in hostile scenarios where malicious nodes intend to jeopardize the delivery of messages. Compromised vehicles can severely affect the performance of the network by a number of attacks, such as selectively dropping messages, manipulating them on the fly, and the likes. One of the best performing solutions that has been used in static wireless sensor networks to deal with these attacks is based on the concept of watchdog nodes (also known as guard nodes) that collaborate to continue the forwarding of data packets in case a malicious behavior in a neighbor node is detected. In this work,we consider the beacon-less routing algorithm for vehicular environments routing protocol, which has been previously shown to perform very well in vehicular networks, and analyze whether a similar solution would be feasible for vehicular environments. Our simulation results in an urban scenario show that watchdog nodes are able to avoid up to a 50% of packet drops across different network densities and for different number of attackers, without introducing a significant increase in terms of control overhead. However, the overall performance of the routing protocol is still far from optimal. Thus, in the case of vehicular networks, watchdog nodes alone are not able to completely alleviate these security threats.
Evaluation of the Use of Guard Nodes for Securing the Routing in VANETs
Martinez, Juan A.,Vigueras, Daniel,Ros, Francisco J.,Ruiz, Pedro M. The Korea Institute of Information and Commucation 2013 Journal of communications and networks Vol.15 No.2
We address the problem of effective vehicular routing in hostile scenarios where malicious nodes intend to jeopardize the delivery of messages. Compromised vehicles can severely affect the performance of the network by a number of attacks, such as selectively dropping messages, manipulating them on the fly, and the likes. One of the best performing solutions that has been used in static wireless sensor networks to deal with these attacks is based on the concept of watchdog nodes (also known as guard nodes) that collaborate to continue the forwarding of data packets in case a malicious behavior in a neighbor node is detected. In this work, we consider the beacon-less routing algorithm for vehicular environments routing protocol, which has been previously shown to perform very well in vehicular networks, and analyze whether a similar solution would be feasible for vehicular environments. Our simulation results in an urban scenario show that watchdog nodes are able to avoid up to a 50% of packet drops across different network densities and for different number of attackers, without introducing a significant increase in terms of control overhead. However, the overall performance of the routing protocol is still far from optimal. Thus, in the case of vehicular networks, watchdog nodes alone are not able to completely alleviate these security threats.
Static wind loads on rigid roof model with complex hyperbolic geometry
Juan S. Delnero,Julio Marañón Di Leo,Mariano A. Martinez 한국풍공학회 2021 Wind and Structures, An International Journal (WAS Vol.33 No.3
The use of tensioned structures, such as membranes, as solutions for roofing and other kinds of covers has become more and more frequent. Current regulations do not provide detailed information about the coefficients needed to develop efficient designs, regarding wind loads. A lot of simulations and tests have been performed on different geometries which are typically used in these kinds of designs. However, no precise and clear standard has been established, yet, in order to regulate efficiently this application. Current regulations consider only simple geometries, while the effects of the interference between multiple covers or between a cover and the near urban environment is completely absent. In this paper are presented the results obtained from testing a 1:75 scale complex geometry model in a boundary layer wind tunnel. More precisely a model of a parking lot for vans, roofed with a complex geometry tensioned membrane was tested in order to measure its pressure distribution. Due to the high complexity of the geometry and in order to obtain a better description of the effects of the wind it was decided to lead wind tunnel tests to validate and to verify the load conditions over the roof. Information about wind load distributions for simple geometries such as cones, hyperboloids, etc. alone can be easily found in current technical bibliography. However, when designs are based on more complex shapes, including arrays of simpler shapes, a profound lack of information is observed. Therefore, it is not possible to calculate the wind loads over the membrane which are needed to dimension the supporting structure.
Iliana Barrera-Martinez,R. Axayácatl González-García,Edgar Salgado-Manjarrez,Juan S. Aranda-Barradas 한국생물공학회 2011 Biotechnology and Bioprocess Engineering Vol.16 No.1
Production of Saccharomyces cerevisiae yeast for applications in the food industry or in bioethanol production still presents important techno-economic challenges as an industrial bioprocess. Mathematical modeling of cellular metabolism in biological production usually improves process yields, though for industrial applications,the model should be as simple as possible in order to sustain model usefulness and technical feasibility. A comparative analysis between a black box description and a simple metabolic network accounting for the main metabolic events involved in yeast growth and bioethanol production is proposed here. In both cases, a thorough analysis of reaction rates allowed for the ethanol concentrations produced in fed-batch yeast cultures, although our results showed more accurate estimations with the metabolic flux balance methodology. Moreover, an interpretation of the yeast physiological state in fed-batch cultures at different glucose feed concentrations was accomplished by means of a stoichiometric analysis linked to the simplified metabolic network. The results confirmed that increasing glucose uptake rates, controlled mainly by the glucose concentration in the input flow, produced an up-regulation in reductive catabolism, resulting in higher ethanol excretion. The biomass production relied mostly on oxidative catabolism,which is controlled by the glucose and oxygen uptake rates. Thus, ethanol or biomass production is strongly dependent on the physiological state of yeast in the culture, which can be inferred from a suitable metabolic flux balance approach.
Broadcast Message Dissemination Schemes for Urban Environments : a Survey
Julio A. Sanguesa,Manuel Fogue,Piedad Garrido,Francisco J. Martinez,Juan-Carlos Cano,Carlos T. Calafate 한국산업정보학회 2014 한국산업정보학회 학술대회논문집 Vol.2014 No.1
In VANKT traffic safety applications, efficient warning message dissemination is required. The main goal is to reduce the latency while ensuring the correct reception of warning information by nearby vehicles when a dangerous situation occurs. So far, several dissemination schemes have been proposed and evaluated under different conditions, and using different simulators, making it difficult to determine which is the optimal dissemination scheme. In this paper, we assess the performance of several existing broadcast dissemination schemes by evaluating them under the same conditions, and focusing on the same metrics, thus providing researchers with a general overview of the drawbacks and benefits associated to each scheme.
Ruiz, Christian C.,Caballero, Jose L.,Martinez, Juan H.,Aperador, Willian A. Techno-Press 2020 Advances in concrete construction Vol.9 No.3
Many failures of concrete structures are related to steel corrosion. For this reason, it is important to recognize how the carbonation can affect the durability of reinforced concrete structures. The repeatability of the carbonation depth measure in a specimen of concrete sprayed with a phenolphthalein solution is consistently low whereby it is necessary to have an impartial method to measure the carbonation depth. This study presents two automatic algorithms to detect the non-carbonated zone in concrete specimens. The first algorithm is based solely on digital processing image (DPI), mainly morphological and threshold techniques. The second algorithm is based on artificial intelligence, more specifically on an array of Kohonen networks, but also using some DPI techniques to refine the results. Moreover, another algorithm was developed with the purpose of measure the carbonation depth from the image obtained previously.