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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Tvorba real-time aplikace pro platformu IMS / Creating real-time IMS application

Novotný, Filip January 2011 (has links)
This paper presents a description of the IP Multimedia Subsystem (IMS) architecture and IMS services. IMS is a standardized next-generation networking architectural framework providing advanced services on mobile and fixed networks. The first chapter describes four-layer IMS architecture and also mentions supported services. The second chapter deals with IMS protocols and primarily focuses on the SIP signaling protocol. UDP, RTP and TLS protocols are also included in this chapter. The third chapter is dedicated to practical part of this paper. A VoIP Java application has been created based on the findings gained throughout the thesis. The main part of the created application consists of client-side application, database MySQL and Servlet application for communication between database and client-side application. The whole system was created using SDS Sony Ericsson 4.1. FD1. An OpenIC lite client has been tested during development on our system and results were compared with created client-side application. A web application based on PHP, MySQL and ActionScript then handles administration and monitoring of customers using voice services.
42

Sledování a účtování provozu IP telefonie / Accounting and Inspecting IP Telephony Traffic

Sivák, Vladimír January 2011 (has links)
This thesis describes architecture of IP telephony networks based on signaling protocol SIP and transport protocol RTP. Also tools used for analyzing VoIP traffic are described. Main objective is to design and implement a system for the detection of calls and extraction of voice payloads from  the captured packets. The system first recognizes the signaling messages of SIP protocol. These messages are analyzed afterwards. Output statistics are generated based on gathered data. Voice data will be stored in form, which is suitable for further processing.
43

Návrh a realizace testeru VoIP protokolů / Design and implementation of VoIP protocols tester

Polášek, Jakub January 2016 (has links)
This paper deals with ways and means of testing SIP or IAX2 based equipment and protocols itselfs. I analyse terminology and methodology for benchmarking of proxy and registrar servers as it was described in documents RFC 7501 and RFC 7502 from organization IETF. In the practical part is described the tester realization programmed in PHP programming language witch will use described methodology. Aplication is available in web based interface.
44

Implementace protokolu SIP v PBX Asterisk / SIP implementations in Asterisk open source PBX

Bednář, Vít January 2017 (has links)
The thesis compares native SIP stack with PJSIP stack in the open source telephone private branch exchange (PBX) Asterisk. First, there are described both SIP protocol and Asterisk application. Subsequently, the architecture, new function support and the stacks setting possibilities are explored. For different exchange scenarios several commented configuration files are presented. The stacks are tested using Spirent TestCenter C1 software thereafter. In conclusion, selected properties are assessed and new PJSIP stack benefits are summarized. In addition, the laboratory assignment is attached.
45

Facilitating the adoption and use of the IP Multimedia System

Papazafeiropoulos, Christos January 2009 (has links)
The IP Multimedia Subsystem (IMS) is still under development and not widely adopted in the market. Some companies are reluctant to deploy IMS and some telecommunications vendors believe that IMS will not achieve a desirable market share. The purpose of this thesis work is to give a boost to this technology (i.e., to accelerate its market growth) by providing the community (both developers and operators who might adopt this technology) with an evaluation of the Ericsson Java Application Programming Interfaces (APIs) called Mobile Java Communication Framework (MJCF) APIs. Developers with or even without knowledge of the IMS architecture and signaling should be able to use these interfaces in order to develop applications on top of IMS. A client-server application is designed and implemented to facilitate this evaluation and to serve as an example for others. The motivation behind this application is the every day needs of the people who search for discounts while they are shopping. Users set up their profile by specifying their preference concerning discounts for specific products; while shop owners publish discounts. When a user is near a store which offers interesting discounts (i.e., discounts that match their profile) new notifications will be sent to his/her mobile device. This application exploits the MJCF APIs and uses several of its basic functions; specifically subscriptions, messages, notifications, and publications are some of the messages that can be utilized through these interfaces.</p> Throughout the application development, bugs were found in the APIs and corrections were suggested for the documentation. Measurements were made in order to evaluate the memory utilization and delay associated with these APIs. It was observed that the delays added by the APIs are somewhat high and may negatively affect the experience of users. However memory utilization seamed to be low for client applications and quite high for the server side given the resources of today's services and cellular phones. / Systemet IP Multimedia Subsystem (IMS) är under utveckling och är inte vida etablerat än. Nogra företag tvekar inför etablering av IMS och nogra telekomföretag anser att IMS inte kommer uppnå önskad marknadsandel. Syftet med detta examensarbete är att ge denna teknologi en skjuts framåt (d.v.s. att öka marknadstillväxten) genom att tillhandahålla den gemenskap av både utvecklare och operatörer som kan tänka sig ta in denna teknologi, med en utvärdering of Ericsson’s Java Applications Programming Interfaces (APIs) kallade MJCF API. Utvecklare med eller t.o.m. utan kunskap om arkitekturen och signalleringen hos IMS ska kunna använda dessa gränssnitt till att utveckla tjänster på IMS. En klient-server applikation är designade och implementerad för att möjliggöra denna utvärdering och för att agera exempel för andra. Motiveringen bakom denna applikation är det vardagliga behovet hos människor som söker efter rabatter/erbjudanden när de handlar. Användare sätter upp sin profil genom att specificera sina önskemål angående erbjudanden för specifika produkter medan butiksinnehavare publicerar sina erbjudanaden. När en användare är nära en butik som erbjuder någonting interessant (d.v.s. produkter som matchar använadarens profil), så kommer nya notifikationer att anlända till hans/hennes mobil. Denna applikation uttnyttjar MJCF APIet och använder ett flertal av dess basala funktioner; speciellt gällande prenumerationer, meddelanden, notifieringar och publiceringar är några av de meddelanden som möjliggörs genom dessa gränssnitt.</p> Genom applikationsutvecklingen så blev flera buggar i APIerna upptäckta och förbättringar till dokumentationen föreslogs. Mätningar gjordes för att utvärdera minnesåtgången och fördröjningar associerade med dessa APIer. Det observerades att API fördröjningar är något höga och kan påverka användarupplevelsen negativt. Däremot verkade minnesåtgången vara låg på klientsidan och hög på serversidan, givet de resurser dagens tjänster och mobila telefoner förfogar över.
46

Charakterisierung des Nitritoxidanten Nitrospira in unterschiedlichen Ökosystemen

Kruse, Myriam 11 October 2011 (has links)
Im Rahmen dieser Studie wurde die chemolithoautotrophe, Nitrit-oxidierende Bakteriengemeinschaft im Belebungsbecken einer kommunalen Kläranlage und im Biofiltersystem mariner Aquakulturanlagen untersucht. Die Zellaktivität der autotrophen Bakteriengemeinschaft ist über die Assimilation von 13C-CO2, welches den Kulturen in Form von stabilen Isotopen zugefügt wurde, ermittelt worden. Der Einbau von 13C in die Zellbestandteile der autotrophen Nitrit-oxidierenden Bakteriengemeinschaft wurde über die Fettsäureanalytik (FAME-SIP) detektierbar und kann über den Markierungsgrad dargestellt werden. Die Assimilierungen des 13C ermöglichen Rückschlüsse auf die metabolische Zellaktivität der Nitritoxidanten. Der chemotaxonomische Ansatz konnte mit molekularbiologischen Untersuchungen ergänzt werden. Hierzu wurden neu entwickelte spezifische Primer und Sonden für die Gattung Nitrospira eingesetzt. Die Primer sind für die spezifische Amplifikation der 16S rRNA verwendet worden, der direkte Nachweis der Organismen erfolgte über die Fluoreszenz in situ Hybridisierung (FISH) mittels Oligonukleotidsonden.
47

Administración de energía en sistemas empaquetados o multi-chip

Soto, Angel José 30 March 2015 (has links)
En los últimos años dispositivos móviles y sistemas de cómputo han logrado disminuir sus tamaños y aumentar su funcionalidad sin sacrificar sus consumos energéticos a través de buenas estrategias de administración de energía. En esta tesis se aborda la implementación de convertidores de potencia para administración de energía. Dos líneas de investigación serán abordadas; la primera a nivel de sistemas empaquetados (system in a package) y la segunda en sistemas en circuitos integrados (system on chip). En la primera parte se presenta un análisis de la técnica de desvío de ondulación (ripple steering) aplicada a tecnologías de cerámicas de baja temperatura de sinterizado (low temperature co-fired ceramics, LTCC) magnético y se analiza la factibilidad de usarla en filtros de potencia. Luego se determina la zona de trabajo en la que el filtro con ripple steering presenta mayor atenuación que un filtro LC de 2do orden con el mismo volumen. Para esto se modela el comportamiento del filtro dependiendo de diferentes parámetros de fabricación y se propone una figura de mérito que evalúa la mejora en la atenuación entre el fltro con ripple steering y el filtro clásico LC de 2do orden con el mismo volumen. Para validar el modelo propuesto y la figura de mérito se construyen inductores acoplados en LTCC que son utilizados en un filtro de potencia. Los resultados experimentales muestran que el filtro con ripple steering se desempeña mejor, con una atenuación 66% más alta que el filtro clásico LC de 2do orden. Ambos filtros son luego utilizados como filtros de salida de un convertidor reductor (buck) y se comprueba que la ondulación de salida (ripple) también es 66% menor para el filtro con ripple steering. En la segunda parte de la tesis se aborda el caso de estudio de un convertidor de múltiples salidas utilizando una única inductancia (single inductor multiple outputs, SIMO) completamente integrado, orientado a la administración de energía dentro de la misma pastilla de silicio (die) de un sistema en circuito integrado. El convertidor posee dos salidas, una reductora (buck) y otra elevadora (boost) de tensión. Para llevar a cabo la implementación se elije una tecnología CMOS de 65 nm, ampliamente utilizada en sistemas en circuitos integrados. Se propone y desarrolla una estrategia de control por histéresis, los módulos y circuitos necesarios para su implementación. Comparadores de alta velocidad, transductores de corriente instantánea y media y los sensores de corriente cero por la inductancia son desarrollados junto con una máquina de estados asincrónica que ofrece las mejores características para el control del sistema. El convertidor desarrollado genera tensiones de 1.2 V y 0.8 V a partir de una tensión de 1 V. Las salidas poseen una regulación del 10% en la condición de máxima carga que es de 50 mA. El convertidor logra un pico de eficiencia mayor al 70 %, que es comparable a la eficiencia reportada en trabajos previos y superior a la que se puede obtener con reguladores lineales. / In recent years, mobile devices and computer systems have reduced their size and increased functionality without increasing their energy consumption through good energy management strategies. In this thesis the implementation of power converters is discussed for power management. Two lines of research will be addressed; the first in system in a package and the second in system on chip. In the first part, an analysis of the ripple steering technique applied to magnetic low temperature co-fired ceramics (LTCC) and the feasibility to be applied to power filters are presented. The working zone where the filter with ripple steering shows a greater attenuation than a LC filter of 2nd order with the same volume is determined. With this purpose, the filter behavior is modeled depending on various manufacturing parameters and a figure of merit which evaluates the improvement in attenuation between the filter with ripple steering and classical LC filter 2nd order with the same volume is proposed. To validate the proposed model and the figure of merit LTCC coupled inductors which are used in a power filter are constructed. Experimental results show that the filter with ripple steering performs better than the classic LC filter 2nd order with an attenuation 66% higher. Both filters are then used as output filters of a buck converter and it can be checked that the output ripple is 66% lower for the filter with ripple steering. In the second part of the thesis the case study of a converter with multiple outputs using a single inductor (SIMO) fully integrated, oriented power management within the same die of a system integrated circuit. The inverter has two outputs, a buck-like and a boost-like. To carry out the implementation, 65 nm CMOS technology is chosen since it is widely used in system on a chip. A hysteretic control strategy is proposed and developed; modules and circuits necessary for its implementation are also carried on. High speed comparators, instantaneous, average and zero inductor current transducers and sensors are developed together with an asynchronous state machine which offers the best features for control the system. The developed converter generates output voltages of 1.2 V and 0.8 V from a input voltage of 1 V. The outputs have a regulation of 10% at maximum load condition (50 mA). The converter achieves a peak eficiency of 70 %, which is better than the expected eficiency of a linear regulator and it is comparable with the fully integrated power converter eficiency previously reported in the literature.
48

Avaliação dos protocolos VoIP SIP e IAX utilizando simulação e parâmetros de qualidade de voz / Evaluation of SIP and IAX VoIP protocols using simulation and parameters of voice quality

Milanez, Mateus Godoi 27 April 2009 (has links)
Recentemente, as tecnologias de telecomunicações esão convergindo para a concepção da Next Generation Network, onde propõe-se que todas as informações trocadas sejam classificadas por prioridade e segurança. Porém, como as redes atuais ainda não promovem tais práticas, protocolos VoIP, em conjunto a outras soluçõoes, buscam a melhoria da qualidade das ligações. Como o protocolo VoIP IAX vem ganhando credibilidade na comunidade open source nos úlltimos anos, torna-se relevante compará-lo ao protocolo SIP, o qual é bastante investigado pela literatura. Desta forma, o objetivo deste trabalho é o estudo e avaliação dos protocolos SIP e IAX, através de verificações de qualidade do áudio em ligações VoIP. Para a realização dos experimentos foi desenvolvida uma estrutura que representasse chamadas VoIP no simulador Network Simulator e, para tais ligações, empregou-se método de avaliação de qualidade PESQ. Assim, foi possível a verficação das semelhanças compreendidas entre os protocolos SIP e IAX diante dos problemas de perda de pacotes, atraso, limitação da taxa de dados e jitter / Telecommunications technologies are recently converging to the Next Generation Network conception, where it is proposed that all exchanged information should be classied by security and priority. As the currently available networks do not provide such practices, VoIP protocols, among other solutions, aim for the improvement of the calls quality. As the IAX VoIP protocol had been receiving credibility in the open source community in the last years, it is relevant to compare it to the SIP protocol, which is widely investigated in the literature. In this way, the objective of this work is the study and evaluation of the SIP and IAX protocols through verications of audio quality in VoIP calls. To implement the experiments, a structure that represents VoIP calls was developed in the \"Network Simulator\" software. For these calls, the PESQ method was used to evaluate the calls quality. Using this approach, it was possible to verify similarities between the SIP and IAX protocols regarding the problems of packet loss, delay, limitation in the data rate and jitter
49

Atténuation naturelle potentielle de BTEX en aquifère de stockage de gaz. / Potential BTEX natural attenuation in gas storage aquifers

Aüllo, Thomas 25 September 2013 (has links)
La France est dépendante en gaz naturel dont elle importe 98% de sa consommation. Comme pour plusieurs autres pays (Etats-Unis, Canada, Grande Bretagne, Autriche, Allemagne, etc.), le stockage de gaz est principalement réalisé afin de pallier aux variations saisonnières de consommation. Grâce aux spécificités géologiques de notre territoire, ce stockage se fait essentiellement aux niveaux d’aquifères très profonds (-500 à 1000 mètres). Le gaz naturel contient en majorité du méthane mais également des traces d’autres composés tels que les BTEX (Benzène, Toluène, Ethylbenzène et les trois isomères du Xylène) qui sont connus pour leur toxicité. Ces hydrocarbures monoaromatiques peuvent se solubiliser dans l’eau de formation aux niveaux des interfaces eau/gaz. Leur biodégradation est bien moins rapide en anaérobiose qu’en aérobiose mais un potentiel d’atténuation naturelle des BTEX par les communautés microbiennes indigènes a déjà pu être démontré lors de travaux antérieurs. Cependant, bien que de nombreuses études aient été réalisées sur le sujet, les voies de dégradation anaérobie ne sont que partiellement connues et les connaissances concernant les microorganismes impliqués sont réduites, voire inexistantes. Le développement de biomarqueurs moléculaires in situ doit permettre d’évaluer rapidement le potentiel de dégradation des microorganismes d’un aquifère. Pour atteindre cet objectif, il est indispensable d’acquérir une meilleure compréhension des mécanismes de dégradation et donc, d’isoler les microorganismes impliqués dans la dégradation de ces composés. Au cours de cette étude, des communautés microbiennes provenant d’échantillons d’eau de formation issue de trois aquifères distincts (nommés dans ce travail A, C et D) ont été étudiées à l’aide de trois approches différentes de microbiologie environnementale. L’ensemble de ces résultats ainsi que ceux de la littérature suggèrent l’ubiquité des bactéries sulfato-réductrices à Gram positif tels que les Desulfotomaculum dans les environnements profonds. Les résultats obtenus lors de ce travail de doctorat suggèrent le rôle prépondérant de microorganismes affiliés au genre Desulfotomaculum dans la dégradation des BTEX en aquifères très profonds et représentent une avancée dans la compréhension des phénomènes d’atténuation naturelle des BTEX dans ce type d’environnement. / France is dependent on natural gas and imports 98% of its consumption. Like in many other countries (The United States of America, Canada, Great Britain, Austria, Germany, etc.), gas storage is primarily performed to compensate for seasonal variations in consumption. Geological characteristics of our territory allow to store essentially natural gas into deep aquifers (-500 to 1000 meters). Natural gas contains mostly methane, but also traces of other compounds such as BTEX (Benzene, Toluene, Ethylbenzene and the three isomers of Xylene) which are known to be toxic. These mono-aromatic hydrocarbons are soluble in water. Anaerobic biodegradation is much slower than aerobic processes however potential for anaerobic BTEX natural attenuation by indigenous microbial communities has already been shown previously. Although many studies have been done on the topic, the anaerobic degradation pathways are only partially known and the knowledge of microorganisms involved is low or nonexistent. The development of in situ molecular biomarkers will allow rapid evaluation of the potential degradation of aquifer microorganisms. To achieve this goal, a better understanding of the mechanisms of degradation is crucial and requires isolation of microorganisms involved in the degradation of these compounds. In this study, microbial communities sampled from formation waters of three distinct aquifers (named in this work A, C and D) were studied using three different environmental microbiology approaches. All these results and those from the literature suggest the ubiquity of sulfate-reducing bacteria such as Gram positive Desulfotomaculum in deep environments. The results obtained during this PhD suggest the importance of microorganisms related to the genus Desulfotomaculum in BTEX degradation in deep aquifers. This work represents a step forward in understanding the phenomenon of natural attenuation of BTEX in this kind of environment.
50

Load balancing of IP telephony / Lastbalansering av IP-telefoni

Montag, David January 2008 (has links)
<p>In today's world, more and more phone calls are made over IP. This results in an increasing demand for scalable IP telephony equipment.</p><p>Ingate Systems AB produces firewalls specialized in handling IP telephony. They have an inherent limit in the number of concurrent phone calls that they can handle. This can be a bottleneck at high loads. There is a load balancing solution available in the platform, but it has a number of drawbacks, such as media latency and client capability requirements, limiting its usage.</p><p>Many companies provide load balancing solutions for SIP. However, it appears few handle all the problematic scenarios that the Ingate firewall does. This master's thesis aims to add load balancing functionality to the Ingate firewall, so that it can handle all types of clients.</p><p>By splitting the firewall into two completely separate layers - a SIP layer and a firewall layer - the concept of a virtual machine emerges. A machine is no longer restricted to its physical SIP and firewall layers. Instead, virtual machines are used to process calls. They still have SIP and firewall layers, but the layers can reside on different physical machines.</p><p>This thesis demonstrates the operation of an innovative load balancing implementation. The implementation was evaluated, and using four machines the test setup performed 50% better than the original Ingate platform, while still retaining all functionality -- something that was not possible with the original platform. This surpassed both the company's and my own expectations.</p>

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