Sittin'On the Dock of the (WiFi) Bay: On the Frame Aggregation under IEEE 802.11 DCF

It is well known that frame aggregation in Internet communications improves transmission efficiency. However, it also causes a delay that for some real-time communications is inappropriate, thus creating a trade-off between efficiency and delay. In this paper, we establish the conditions for frame aggregation under the IEEE 802.11 DCF protocol to be beneficial on average delay. To do so, we first describe the transmission time in IEEE 802.11 in a stochastic framework and then we calculate the optimal value of the frames that, when aggregated, saves transmission time in the long term. Our findings, discussed with numerical experimentation, show that frame aggregation reduces transmission congestion and transmission delays

Some Experiments in Evaluating ASR Systems Applied to Multimedia Retrieval

Proceedings of: 7th International Workshop on Adaptive Multimedia Retrieval (AMR 2009). Took place 2009, September 24-25, in Madrid. The event Web site is http://nlp.uned.es/amr2009/This paper describes some tests performed on different types of voice/audio input applying three commercial speech recognition tools. Three multimedia retrieval scenarios are considered: a question answering system, an automatic transcription of audio from video files and a real-time captioning system used in the classroom for deaf students. A software tool, RET (Recognition Evaluation Tool), has been developed to test the output of commercial ASR systems.This research work has been supported by the Regional Government of Madrid under the Research Network MA2VICMR (S2009/TIC-1542) and by the Spanish Ministry of Education under the project BRAVO (TIN2007-67407-C03-01).Publicad

Colección Diplomática del Concejo de Segura (Guipúzcoa). (1290-1400)

Los fondos seguratarras son en cuanto a su cantidad (y en lo que refiere a documentación medieval), considerables. Buena parte de sus fondos refieren a un interés local, pero también hay documentación referente a lugares, personas e instituciones extra-municipales e igualmente destacan ciertos documentos que tienen un evidente interés provincial. Este volumen recoge la documentación situada cronológicamente entre 1290 y 140

Colección Diplomática del Concejo de Segura (Guipúzcoa). (1401-1450)

Los fondos seguratarras son en cuanto a su cantidad (y en lo que refiere a documentación medieval), considerables. Buena parte de sus fondos refieren a un interés local, pero también hay documentación referente a lugares, personas e instituciones extra-municipales e igualmente destacan ciertos documentos que tienen un evidente interés provincial. Este es el segundo volumen dedicado a esta colección diplomática en el que se recoge la documentación fechada entre 1401 y 1500

A nationwide study of chronic pain prevalence in the general Spanish population, identifying clinical subgroups through cluster analysis.

Objective. This study aims to assess the prevalence of chronic pain, its characteristics, and its impact on the general Spanish population. Also, to establish chronic pain patient subgroups according to the characteristics of pain and to identify variables specifically associated with each subgroup. Design. Telephone-based, cross-sectional nationwide study. Subjects. A sample of 1,957 individuals representative of the Spanish population. Methods. Data were collected through telephone interviews. A subject was considered to have chronic pain if they had suffered pain (at least 4 days a week) during the last 3 months. The subjects were divided into two subgroups through a cluster analysis, and a regression model was established to determine the variables most specifically associated with these subgroups. Results. The prevalence of chronic pain was 16.6% (95% confidence interval: 14.9–18.3) and among these subjects, more than 50% referred to limitations in their daily activities, 30% felt sad and/or anxious, and 47.2% indicated that their pain was affecting their family life. Two subgroups of subjects with pain were identified: 1) characterized by generalized pain in more than one location and of a long evolution (150 months); and 2) characterized by pain localized to only one site with a shorter duration (100 months). Individuals who felt anxious because of their pain and those who considered that their pain was affecting their family were more likely to belong to group 1. Conclusions. Pain affects an important proportion of the Spanish adult population and that it has a strong personal impact. Two pain groups were clearly distinguished by their clinical characteristics

Propuesta de diseño de cámaras de bombeo, cámara húmeda, cámara seca, cámara rejas, cámara arqueta en Ancón – Lima, 2021

El propósito de esta investigación es el de proponer un diseño de cámaras de bombeo que beneficiarán a la red de desagüe del distrito de Ancón en Lima, se realizó el análisis y se propone el diseño estructural de una cámara húmeda, una cámara seca, una cámara de rejas y una cámara arqueta. El análisis y diseño fue realizado bajo el método LRFD que figura en las normas AASHTO, y con base también en la normativa peruana como son las normas técnicas E.020 Cargas, E.030 Diseño sismorresistente, E.050 Suelos y Cimentaciones, E.060 Concreto Armado, además de las normas OS.050 Redes de distribución de agua para consumo humano y OS.090 Plantas de tratamiento de aguas residuales. La investigación realizada es de una metodología tipo de investigación aplicada y el diseño de investigación es no experimental, por la segunda característica la información generada se usará en un tiempo determinado y documental. La información utilizada en este trabajo tiene un análisis interpretativo de los datos aportados por una revisión documental de la información dada por estudios realizados por la Municipalidad Distrital de Ancón conjuntamente con la empresa SEDAPAL, en donde determinan los datos pertinentes para poder realizar este diseño. Con lo cual se obtuvo lo siguiente Cámara Seca (techo 5/8”@0.20m, muros doble malla ½”@0.25 m, losa de piso doble malla ½”@0.25 m); Cámara Húmeda (techo 3/8”@0.175m, muros doble malla ½”@0.175 m, losa de piso doble malla ½”@0.25 m), Cámara Rejas (techo 1/2”@0.15m, muros doble malla ½”@0.15 m, losa de piso doble malla ½”@0.15 m), Cámara Arqueta (muros doble malla ½”@0.15 m, losa de piso doble malla ½”@0.15 m)

Short message multichannel broadcast encryption

The current use of short messages in wireless networks is highly growing. Messaging applications in mobile terminals with wireless coverage are very common in shopping, educational and transport centers, i.e. in centers of massive influx of people. This requires improving its efficiency, without losing security in such a hostile environment. In this paper, we propose an improvement in the use of the medium through a new multichannel broadcast encryption paradigm. Firstly, we rigorously demonstrate the security of our model that is characterized by two main issues: short messages and maintaining privacy in a shared frame. The improvements are obtained by reducing the transmitted overheads, saving bandwidth and airtime. To implement them, we improve the efficiency of communications, reducing the security headers to a single one, which will be shared by all receivers, while the payload is multiplexed via Chinese Remainder Theorem. In this way we reduce the packet length (less headers) and set the ratio of the encrypted text/plaintext equals to one, if we do not take into account padding and security headers. Although the model can be used by all types of networks, both wired and wireless, the improvement is more noticeable in the latter type. To make it remarkable, we quantify what this gain will consist of