Fuel spray diagnostics

Several laser measurement methods are being studied to provide the capability to make droplet size and velocity measurements under a variety of spray conditions. The droplet sizing interferometer (DSI) promises to be a successful technique because of its capability for rapid data acquisition, compilation and analysis. Its main advantage is the ability to obtain size and velocity measurements in air-fuel mixing studies and hot flows. The existing DSI at NASA Lewis is a two-color, two-component system. Two independent orthogonal measurements of size and velocity components can be made simultaneously. It also uses an off-axis large-angle light scatter detection. The fundamental features of the system are optics, signal processing and data management system. The major component includes a transmitter unit, two receiver units, two signal processors, two data management systems, two Bragg cell systems, two printer/plotters, a laser, power supply and color monitor

Fuel Spray Diagnostics

Fundamental experimental data base for turbulent flow mixing models is provided and better prediction of the more complex turbulent chemical reacting flows. Analytical application to combustor design is provided and a better fundamental understanding of the combustion process

Un modelo multirregional para la proyección de la población de las provincias españolas

La realización de proyecciones de población es un tema de estudio con cierta tradición pero que, a consecuencia de su complejidad y dificultad, no ha sido abordado adecuadamente en nuestro país, ya sea en número de trabajos como en validez de sus resultados - En especial se echan en falta proyecciones de la población española donde se tenga en cuenta explícitamente la dirección de los flujos migratorios interprovinciales. El objetivo de este trabajo es dar un paso adelante en este sentido. En la actualidad diversos grupos de investigación, tanto demógrafos como geógrafos, intentan desarrollar métodos y técnicas donde el espacio intervenga de modo explícito en los análisis demográficos.Peer reviewe

Libraries Atwitter: Trends in Academic Library Tweeting

Purpose – This paper aims to present an overview of how libraries are using Twitter in an academic setting. Design/methodology/approach – This study analyzed the current state of 296 Twitter accounts from a random sample of academic libraries. A total of 19 different criteria were explored, with an emphasis on the following three categories: layout and design, content and number of tweets, and account followers. Findings – Only 34 per cent of libraries in the study had a Twitter account and characteristics varied widely among libraries, however it is evident that it is possible to successfully communicate with patrons via Twitter. Research limitations/implications – A primary limitation for this study is the frequency with which Twitter can change. Practical implications – This paper provides a snapshot of how libraries are currently using Twitter, which can be of assistance to libraries seeking to implement a Twitter presence. Originality/value – The paper presents an overview of trends in academic library Twitter accounts, which could be useful to librarians who are considering launching a Twitter account for their library

Self-synchronized Encryption for Physical Layer in 10Gbps Optical Links

In this work a new self-synchronized encryption method for 10 Gigabit optical links is proposed and developed. Necessary modifications to introduce this kind of encryption in physical layers based on 64b/66b encoding, such as 10GBase-R, have been considered. The proposed scheme encrypts directly the 64b/66b blocks by using a symmetric stream cipher based on an FPE (Format Preserving Encryption) block cipher operating in PSCFB (Pipelined Statistical Cipher Feedback) mode. One of the main novelties in this paper is the security analysis done for this mode. For the first time, an expression for the IND-CPA (Indistinguishability under Chosen-Plaintext Attack) advantage of any adversary over this scheme has been derived. Moreover, it has been concluded that this mode can be considered secure in the same way of traditional modes are. In addition, the overall system has been simulated and implemented in an FPGA (Field Programmable Gate Array). An encrypted optical link has been tested with Ethernet data frames, concluding that it is possible to cipher traffic at this level, getting maximum throughput and hiding traffic pattern from passive eavesdroppers

A new simple technique for improving the random properties of chaos-based cryptosystems

A new technique for improving the security of chaos-based stream ciphers has been proposed and tested experimentally. This technique manages to improve the randomness properties of the generated keystream by preventing the system to fall into short period cycles due to digitation. In order to test this technique, a stream cipher based on a Skew Tent Map algorithm has been implemented on a Virtex 7 FPGA. The randomness of the keystream generated by this system has been compared to the randomness of the keystream generated by the same system with the proposed randomness-enhancement technique. By subjecting both keystreams to the National Institute of Standards and Technology (NIST) tests, we have proved that our method can considerably improve the randomness of the generated keystreams. In order to incorporate our randomness-enhancement technique, only 41 extra slices have been needed, proving that, apart from effective, this method is also efficient in terms of area and hardware resources

Physical Layer Encryption for Industrial Ethernet in Gigabit Optical Links

Industrial Ethernet is a technology widely spread in factory floors and critical infrastructures where a high amount of data need to be collected and transported. Fiber optic networks at gigabit rates fit well with that type of environment, where speed, system performance, and reliability are critical. In this paper, a new encryption method for high-speed optical communications suitable for such kinds of networks is proposed. This new encryption method consists of a symmetric streaming encryption of the 8b/10b data flow at physical coding sublayer level. It is carried out thanks to a format preserving encryption block cipher working in CTR (counter) mode. The overall system has been simulated and implemented in a field programmable gate array. Thanks to experimental results, it can be concluded that it is possible to cipher traffic at this physical level in a secure way. In addition, no overhead is introduced during encryption, getting minimum latency and maximum throughput

Thermoelectric properties of directionally grown Bi2Ba2Co2Oδ/Ag composites: effect of annealing

Bi2Ba2Co2Oδ thermoelectric ceramics with Ag additions (0, 1, 3, and 5 wt%) have been successfully textured using the laser floating zone method. Microstructure has shown that samples are composed by thermoelectric grains, together with a high amount of secondary phases, and that 3 wt% Ag addition leads to the best grain orientation. These microstructural benefits have been reflected in the highest thermoelectric performances determined in these samples. It has also been found that annealing procedure leads to a drastic decrease of secondary phases amount and raises the oxygen content in the thermoelectric phase. These modifications are reflected in an important decrease of electrical resistivity, ρ (compared to the as-grown samples) without drastic modification of Seebeck coefficient, S. As a consequence, the highest thermoelectric performances, determined through the power factor, have been reached in the 3 wt% Ag textured and annealed samples in the whole measured temperature range. The maximum PF (=S/ρ) values at 650 °C determined in these samples are very close to the highest reported in single crystals or very low rate LFZ grown Bi2Ba2Co2Oδ compounds, making them very attractive for practical applications.This research has been supported by the Spanish MINECO-FEDER (MAT2013-46505-C3-1-R). The authors wish to thank the Gobierno de Aragón and Fondo Social Europeo (Consolidated Research Groups T87 and T12) for financial support.Peer Reviewe

Chaotic Encryption for 10-Gb Ethernet Optical Links

In this paper, a new physical layer encryption method for optical 10-Gb Ethernet links is proposed. Necessary modifications to introduce encryption in Ethernet 10GBase-R standard have been considered. This security enhancement has consisted of a symmetric streaming encryption of the 64b/66b data flow at physical coding sublayer level thanks to two keystream generators based on a chaotic algorithm. The overall system has been implemented and tested in a field programmable gate array. Ethernet traffic has been encrypted, transmitted, and decrypted over a multimode optical link. Experimental results are analyzed concluding that it is possible to cipher traffic at this level and hide the complete Ethernet traffic pattern from any passive eavesdropper. In addition, no overhead is introduced during encryption, getting no losses in the total throughput