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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.
1

A Dynamic Navigational Algorithm for VANET

Sung, Wei-Cheng 11 September 2009 (has links)
In recent years, road navigational devices equipped with GPS technologies are becoming more and more popular. These devices can facilitate drivers to guide the way to reach their destinations. In this Thesis, we propose a dynamic route navigational algorithm (DNA) that can be combined with GPS, electronic map system, and wireless technologies (such as DSRC, VANET, 802.11p, WLAN, WiMAX ..., etc.). By calculating metric from road type, road length, average distance, and average speed of each available candidate road, DNA generates road score table and choose the route with the highest score among candidate routes to reach destination. Additionally, in DNA, a Dynamic Block re-Broadcasting (DBB) scheme is designed to carry out Road-Request message (R-REQ) rebroadcast function. The R-REQ rebroadcast function provides two advantages: (i) It can broadcast R-REQ to a specific coverage area with least hop counts; (ii) It can reduce the number of R-REQ broadcast packets significantly. Although DNA takes more processing time than other navigational algorithms, it can greatly reduce the traveling time by determining the best route to destination. For the purpose of performance evaluation, we develop a simulator by using C++ programming language to compare the performance of DNA with other navigational algorithms. Simulation results have shown that DNA performs much better than other navigational algorithms in reaching destination with shorter travel distance and shorter traveling time.
2

Neue Technologien für hochzuverlässige Aufbau- und Verbindungstechniken leistungselektronischer Bauteile

Becker, Martin 03 November 2015 (has links) (PDF)
Achieving the utmost reliability of power semiconductors is an ongoing challenge for the scientists and engineers in the packaging community of the industry and research institutions. Still the semiconductor and therefore the function of the power module could live longer, when only the bonding and joining technologies would be more stable against power and temperature cycling wearout. In particular, the conventional electrical connection to the top and bottom surface of the semiconductor is limiting the lifetime due to degradation. For both, the solder layer under the backside and the Al-wire on the topside of the die, it is necessary to develop new contact technologies, as the substitution of just one connection does not perform the required reliability of the module. In this work, different new technologies for power modules were evaluated and an own development is presented. Especially the new development is characterized by an outstanding reliability while keeping the design flexibility of the currently applied methods. To achieve that, the solder joints were replaced by Ag-sintered connections and Cu-wires were bonded as a substitute of Al-wires. This new approach is called DBB-Technology („Danfoss BondBuffer“) and is demonstrated in the example of a 1700V DBB power module. With the help of this technology sintering creates two joints: One between the bottom of die and the substrate and between the die and a thin Cu-foil, which is located on top. This Cu foil (BondBuffer) enables the Cu-bond process as top contact technology without damaging the semiconductor. The DBB Cu foil acts as an absorber for the high bond-forces. The detailed characterization of a DBB-covered semiconductor module reveals an extraordinary high reliability improvement, enhanced thermal impedance and upgraded electrical properties. / Leistungsmodule unterliegen in der Anwendung vielfältigen, kombinierten Beanspruchungen, die je nach Anwendung eine Herausforderung an unterschiedliche Verbindungsstellen im Modul darstellen. Die Betriebsdauer eines Leistungsmoduls wird im Wesentlichen von den halbleiternahen Aufbau- und Verbindungstechniken limitiert. Das geht z.B. aus umfangreichen Lastwechseluntersuchungen hervor, in denen als Fehlermechanismen die Zerrüttung des Lots unter dem Chip oder das Abheben des Aluminium-Bonddrahts vom Halbleiter identifiziert wurden. Die einzelnen Verbindungsschichten im Leistungsmodul bilden eine Funktionskette, die beim Ausfall nur eines Gliedes die gesamte Funktionalität verliert. Maßnahmen zur Optimierung einzelner Schichten, z. B. der Halbleiter-Substrat-Verbindung oder nur der oberseitigen Chipkontaktierung, bringen alleinstehend also nicht den gewünschten Erfolg. In dieser Arbeit werden unterschiedliche Aufbaukonzepte leistungselektronischer Module aus Fachveröffentlichungen verglichen, bevor das eigene Konzept beschrieben wird. Die Lösung basiert dabei auf innovativen und sehr robusten Fügetechnologien, die gezielt herkömmliche Verbindungen im Aufbau ersetzen. Das Ergebnis ist ein Leistungsmodul mit verbesserten thermischen, elektrischen und thermo-mechanischen Eigenschaften. Eine wesentliche Rolle spielt dabei das Silbersintern als Alternative zum Löten. Dank der Sintertechnik geht der Halbleiter eine hochfeste Verbindung mit dem Substrat ein. Darüber hinaus ermöglicht die Sintertechnologie das stoffschlüssige Verbinden einer dünnen Kupferfolie mit der oberen Halbleitermetallisierung. Diese Kupferfolie ist erforderlich, um das Cu-Drahtbonden für die oberseitige Kontaktierung der Halbleiter anzuwenden, ohne diesen aufgrund hoher Bondkräfte zu zerstören. Dank der vorteilhaften Materialeigenschaften ist die Cu-Bondverbindung deutlich leistungsfähiger als eine Al-Bondverbindung. Diese Kombination aus robusten Fügestellen trägt den Namen DBB-Technologie („Danfoss BondBuffer“) und soll zukünftig dank der Verfügbarkeit sinterbarer Halbleiter in hochzuverlässigen Leistungsmodulen angewendet werden.
3

Integrated Project Delivery (IPD): Un marco integrador de ejecución de proyectos

Pila Huancachoque, Yuri Gabriel 10 April 2018 (has links)
Los proyectos de construcción suelen tener relaciones adversarias entre colaboradores, bajos ratios de productividad, alto grado de ineficiencia y re trabajo, frecuentes disputas y poca innovación. Como resultado, se tienen proyectos que son muy costosos y que no cumplen con los plazos especificados. Este panorama puede ser visto desde enfoques diversos de solución, empezando por la mejora de la productividad, la tecnología, entre otros. Sin embargo, es necesario revisar las bases mismas de la relación entre las empresas que forman parte de un proyecto y, a partir de ello, presentar un nuevo modo de trabajo colaborativo: el IPD, un marco de trabajo integrador de resultados fascinantes.
4

Atividade in vitro de formulações de lípides catiônicos contra bactérias multirresistentes, fungos e microalgas de interesse médico humano e veterinário. / In vitro activity of cationic lipids formulations against multiresistants bacterias, fungi and microalgae from human and veterinary medical interest.

Bentivoglio, Enyd Crystina Rodrigues de Oliveira 29 August 2016 (has links)
Infecções microbianas podem ser causadas por bactérias, fungos, vírus, parasitas e algas. O presente estudo avaliou a atividade in vitro de formulações de lípides catiônicos contra bactérias multirresistêntes (MRs), fungos e microalgas de interesse médico humano e veterinário. A atividade biocida de bicelas de brometo de dioctadecildimetilamônio (DBB) foi avaliada contra bactérias gram-negativas produtoras de β-lactamases de amplo espectro e carbapenemases mundialmente disseminadas. Para fungos (Candida albicans, Trichophyton rubrum) e microalgas (Prototheca zopfii), a atividade biocida de DBB, sem e com a associação a drogas antifúngicas (ex., miconazol, terbinafina e anfotericina B), foi avaliada determinando-se adicionalmente a atividade sinérgica. Nanodispersões catiônicas de DBB exibiram atividade bactericida, fungicida e algicida, mesmo para patógenos MRs, sendo que a sua associação com outros antimicrobianos resultou em uma atividade sinérgica que poderia favorecer a produção de formulações com potencial para aplicação clínica humana e veterinária. / Microbial infections can be caused by bactérias, fungi, virus, parasites and algae. This study evaluated in vitro activity from cationic lipds formulations against multiresistant bacterias (MRs), fungi and e microalgae from human and veterinary. The Biocidal activity from bromide dioctadecildimetilammonium biceles (DBB) was evaluated against gram-negative bactérias β-lactamases producers and carbapenemases from broad spectrum with wide spread dissemination. For fungi (Candida albicans, Trichophyton rubrum) and microalgae (Prototheca zopfii), the biocidal activity from DBB wuth and without antifungal drugs (ex., miconazole, terbinafine e amphotericin B), was also evaluated by synergistic activity. Cationic nanodispertions of DBB has shown bactericidal, fungicidal and algicidal activity, even for MRs patogens, thus , the association with the others antimicrobials resulted in a synergistic activity wich could foment the production of the formulations with a potential application in human and veterinary medicine.
5

Atividade in vitro de formulações de lípides catiônicos contra bactérias multirresistentes, fungos e microalgas de interesse médico humano e veterinário. / In vitro activity of cationic lipids formulations against multiresistants bacterias, fungi and microalgae from human and veterinary medical interest.

Enyd Crystina Rodrigues de Oliveira Bentivoglio 29 August 2016 (has links)
Infecções microbianas podem ser causadas por bactérias, fungos, vírus, parasitas e algas. O presente estudo avaliou a atividade in vitro de formulações de lípides catiônicos contra bactérias multirresistêntes (MRs), fungos e microalgas de interesse médico humano e veterinário. A atividade biocida de bicelas de brometo de dioctadecildimetilamônio (DBB) foi avaliada contra bactérias gram-negativas produtoras de β-lactamases de amplo espectro e carbapenemases mundialmente disseminadas. Para fungos (Candida albicans, Trichophyton rubrum) e microalgas (Prototheca zopfii), a atividade biocida de DBB, sem e com a associação a drogas antifúngicas (ex., miconazol, terbinafina e anfotericina B), foi avaliada determinando-se adicionalmente a atividade sinérgica. Nanodispersões catiônicas de DBB exibiram atividade bactericida, fungicida e algicida, mesmo para patógenos MRs, sendo que a sua associação com outros antimicrobianos resultou em uma atividade sinérgica que poderia favorecer a produção de formulações com potencial para aplicação clínica humana e veterinária. / Microbial infections can be caused by bactérias, fungi, virus, parasites and algae. This study evaluated in vitro activity from cationic lipds formulations against multiresistant bacterias (MRs), fungi and e microalgae from human and veterinary. The Biocidal activity from bromide dioctadecildimetilammonium biceles (DBB) was evaluated against gram-negative bactérias β-lactamases producers and carbapenemases from broad spectrum with wide spread dissemination. For fungi (Candida albicans, Trichophyton rubrum) and microalgae (Prototheca zopfii), the biocidal activity from DBB wuth and without antifungal drugs (ex., miconazole, terbinafine e amphotericin B), was also evaluated by synergistic activity. Cationic nanodispertions of DBB has shown bactericidal, fungicidal and algicidal activity, even for MRs patogens, thus , the association with the others antimicrobials resulted in a synergistic activity wich could foment the production of the formulations with a potential application in human and veterinary medicine.
6

Neue Technologien für hochzuverlässige Aufbau- und Verbindungstechniken leistungselektronischer Bauteile

Becker, Martin 17 September 2015 (has links)
Achieving the utmost reliability of power semiconductors is an ongoing challenge for the scientists and engineers in the packaging community of the industry and research institutions. Still the semiconductor and therefore the function of the power module could live longer, when only the bonding and joining technologies would be more stable against power and temperature cycling wearout. In particular, the conventional electrical connection to the top and bottom surface of the semiconductor is limiting the lifetime due to degradation. For both, the solder layer under the backside and the Al-wire on the topside of the die, it is necessary to develop new contact technologies, as the substitution of just one connection does not perform the required reliability of the module. In this work, different new technologies for power modules were evaluated and an own development is presented. Especially the new development is characterized by an outstanding reliability while keeping the design flexibility of the currently applied methods. To achieve that, the solder joints were replaced by Ag-sintered connections and Cu-wires were bonded as a substitute of Al-wires. This new approach is called DBB-Technology („Danfoss BondBuffer“) and is demonstrated in the example of a 1700V DBB power module. With the help of this technology sintering creates two joints: One between the bottom of die and the substrate and between the die and a thin Cu-foil, which is located on top. This Cu foil (BondBuffer) enables the Cu-bond process as top contact technology without damaging the semiconductor. The DBB Cu foil acts as an absorber for the high bond-forces. The detailed characterization of a DBB-covered semiconductor module reveals an extraordinary high reliability improvement, enhanced thermal impedance and upgraded electrical properties. / Leistungsmodule unterliegen in der Anwendung vielfältigen, kombinierten Beanspruchungen, die je nach Anwendung eine Herausforderung an unterschiedliche Verbindungsstellen im Modul darstellen. Die Betriebsdauer eines Leistungsmoduls wird im Wesentlichen von den halbleiternahen Aufbau- und Verbindungstechniken limitiert. Das geht z.B. aus umfangreichen Lastwechseluntersuchungen hervor, in denen als Fehlermechanismen die Zerrüttung des Lots unter dem Chip oder das Abheben des Aluminium-Bonddrahts vom Halbleiter identifiziert wurden. Die einzelnen Verbindungsschichten im Leistungsmodul bilden eine Funktionskette, die beim Ausfall nur eines Gliedes die gesamte Funktionalität verliert. Maßnahmen zur Optimierung einzelner Schichten, z. B. der Halbleiter-Substrat-Verbindung oder nur der oberseitigen Chipkontaktierung, bringen alleinstehend also nicht den gewünschten Erfolg. In dieser Arbeit werden unterschiedliche Aufbaukonzepte leistungselektronischer Module aus Fachveröffentlichungen verglichen, bevor das eigene Konzept beschrieben wird. Die Lösung basiert dabei auf innovativen und sehr robusten Fügetechnologien, die gezielt herkömmliche Verbindungen im Aufbau ersetzen. Das Ergebnis ist ein Leistungsmodul mit verbesserten thermischen, elektrischen und thermo-mechanischen Eigenschaften. Eine wesentliche Rolle spielt dabei das Silbersintern als Alternative zum Löten. Dank der Sintertechnik geht der Halbleiter eine hochfeste Verbindung mit dem Substrat ein. Darüber hinaus ermöglicht die Sintertechnologie das stoffschlüssige Verbinden einer dünnen Kupferfolie mit der oberen Halbleitermetallisierung. Diese Kupferfolie ist erforderlich, um das Cu-Drahtbonden für die oberseitige Kontaktierung der Halbleiter anzuwenden, ohne diesen aufgrund hoher Bondkräfte zu zerstören. Dank der vorteilhaften Materialeigenschaften ist die Cu-Bondverbindung deutlich leistungsfähiger als eine Al-Bondverbindung. Diese Kombination aus robusten Fügestellen trägt den Namen DBB-Technologie („Danfoss BondBuffer“) und soll zukünftig dank der Verfügbarkeit sinterbarer Halbleiter in hochzuverlässigen Leistungsmodulen angewendet werden.

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