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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.
31

Vybrané problémy provozu dopravní firmy MKD / Various problems of running an international haulage

Kadavá, Eva January 2010 (has links)
Transport sector as a whole records growing trend, whereas road transport has recorded the biggest growth of transported goods. An increase in international trade brings more opportunities for firms involved in the haulage industry. The aim of this thesis is to show the basic requirements in order to set up the haulage and forwarding business. I will mention various factors, that influence the transport market. In other chapters I will analyze laws and treaties, which every haulage company has to adhere to. The last chapter is devoted to problems of financing truck fleet. In the end there is a summary of ways on how to tackle and reduce non-payment by clients.
32

Zasílatelská smlouva, aktuální a navrhovaná právní úprava / Forwarding Contract, actual and planned legislation

Mrkvová, Petra January 2011 (has links)
The thesis focuses on the Czech regulation of forwarding contract. The aim of this thesis is to answer the question whether planned legislation in The New Czech Civil Code is type of modern legislation, which takes into account the needs of freight forwarders and international developments in the unification and harmonization of forwarding contract. The answer is based on analysis of the current legislation of forwarding contract, jurisprudence and comparison with regulation abroad.
33

Overlay Neighborhoods for Distributed Publish/Subscribe Systems

Sherafat Kazemzadeh, Reza 07 January 2013 (has links)
The Publish/Subscribe (pub/sub) model has been widely applied in a variety of application scenarios which demand loose-coupling and asynchronous communication between a large number of information sources and sinks. In this model, clients are granted the flexibility to specify their interests at a high level and rely on the pub/sub middleware for delivery of their publications of interest. This increased flexibility and ease of use on the client side results in substantial complexity on part of the pub/sub middleware implementation. Furthermore, for several reasons including improved scalability, availability and avoiding a single point of failure, the pub/sub middleware is commonly composed of a set of collaborating message routers, a.k.a. brokers. The distributed nature of this design further introduces new challenges in ensuring end-to-end reliability as well as efficiency of operation. These challenges are largely unique to the pub/sub model and hence absent in both point-to-point or multicast protocols. This thesis develops solutions that ensure the dependable operation of the pub/sub system by exploiting the notion of overlay neighborhoods in a formal manner. More specifically, brokers maintain information about their neighbors within a configurable distance in the pub/sub overlay and exploit this knowledge to construct alternative forwarding paths or make smart forwarding decisions that improves efficiency, bandwidth utilization and delivery delay, all at the same time. Furthermore, in the face of failures overlay neighborhoods enable fast reconstruction of forwarding paths in the system without compromising its reliability and availability. Finally, as an added benefit of overlay neighborhoods, this thesis develops large-scale algorithms that bring the advantages of the pub/sub model to the domain of file sharing and bulk content dissemination applications. Experimental evaluation results with deployments as large as 1000 nodes illustrate that the pub/sub system scales well and outperforms the traditional BitTorrent protocol in terms of content dissemination delay.
34

Many-to-Many Multicast/Broadcast Support for Mobile Ad Hoc Networks

Hsia, Ming-Chun 25 June 2003 (has links)
Broadcasting is a fundamental primitive in local area networks (LANs).Operations of many data link protocols, for example, ARP (Address Resolution Protocol) and IGMP (Internet Group Management Protocol), must rely on this LAN primitive. To develop the broadcasting service in mobile ad hoc wireless LANs (WLANs) is a challenge. This is because a mobile ad hoc WLAN is a multi-hop wireless network in which messages may travel along several links from the source to the destination via a certain path. Additionally, there is no fixed network topology because of host moving. Furthermore, the broadcast nature of a radio channel makes a packet be transmitted by a node to be able to reach all neighbors. Therefore, the total number of transmissions (forward nodes) is generally used as the cost criterion for broadcasting. The problem of finding the minimum number of forward nodes in a static radio network is NP-complete. Almost all previous works, therefore, for broadcasting in the WLAN are focusing on finding approximation approaches in a, rather than, environment. In this paper, we propose a novel distributed protocol in WLANs to significantly reduce or eliminate the communication overhead in addition to maintaining positions of neighboring nodes. The important features of our proposed protocol are the adaptability to dynamic network topology change and the utilization of the existing routing protocol. The reduction in communication overhead for broadcasting operation is measured experimentally. From the simulation results, our protocol not only has the similar performance as the approximation approaches in the static network, but also outperforms existing ones in the adaptability to host moving.
35

Adaptive Forwarding in Named Data Networking

Yi, Cheng January 2014 (has links)
Named Data Networking (NDN) is a recently proposed new Internet architecture. By naming data instead of locations, it changes the very basic network service abstraction from "delivering packets to given destinations" to "retrieving data of given names." This fundamental change creates an abundance of new opportunities as well as many intellectual challenges in application development, network routing and forwarding, communication security and privacy. The focus of this dissertation is a unique feature introduced by NDN: its adaptive forwarding plane. Communication in NDN is done by exchanges of Interest and Data packets. Consumers send Interest packets to request desired Data, routers forward them based on data names, and producers answer with Data packets, which take the same path of Interests but in reverse direction. During this process, routers maintain state information of pending Interests. This state information, coupled with the symmetric exchange of Interest and Data, enables NDN routers to detect loops, observe data retrieval performance, and explore multiple forwarding paths, all at the forwarding plane. Since NDN is still in its early stage, however, none of these powerful features has been systematically designed, valuated, or explored. In this dissertation, we present a concrete design of NDN's forwarding plane to make the network resilient and efficient. First, we design the basic adaptation mechanism and evaluate its effectiveness in circumventing prefix hijack attacks. Second, we propose a novel NACK mechanism for fast failure detection and evaluate its benefits in handling network failures. We also show that a resilient forwarding plane makes routing more stable and more scalable. Third, we design a congestion control mechanism, Dynamic Interest Limiting, to adapt traffic rate in a hop-by-hop and multipath fashion, which is effective even with a large number of flows in a large network topology.
36

Overlay Neighborhoods for Distributed Publish/Subscribe Systems

Sherafat Kazemzadeh, Reza 07 January 2013 (has links)
The Publish/Subscribe (pub/sub) model has been widely applied in a variety of application scenarios which demand loose-coupling and asynchronous communication between a large number of information sources and sinks. In this model, clients are granted the flexibility to specify their interests at a high level and rely on the pub/sub middleware for delivery of their publications of interest. This increased flexibility and ease of use on the client side results in substantial complexity on part of the pub/sub middleware implementation. Furthermore, for several reasons including improved scalability, availability and avoiding a single point of failure, the pub/sub middleware is commonly composed of a set of collaborating message routers, a.k.a. brokers. The distributed nature of this design further introduces new challenges in ensuring end-to-end reliability as well as efficiency of operation. These challenges are largely unique to the pub/sub model and hence absent in both point-to-point or multicast protocols. This thesis develops solutions that ensure the dependable operation of the pub/sub system by exploiting the notion of overlay neighborhoods in a formal manner. More specifically, brokers maintain information about their neighbors within a configurable distance in the pub/sub overlay and exploit this knowledge to construct alternative forwarding paths or make smart forwarding decisions that improves efficiency, bandwidth utilization and delivery delay, all at the same time. Furthermore, in the face of failures overlay neighborhoods enable fast reconstruction of forwarding paths in the system without compromising its reliability and availability. Finally, as an added benefit of overlay neighborhoods, this thesis develops large-scale algorithms that bring the advantages of the pub/sub model to the domain of file sharing and bulk content dissemination applications. Experimental evaluation results with deployments as large as 1000 nodes illustrate that the pub/sub system scales well and outperforms the traditional BitTorrent protocol in terms of content dissemination delay.
37

Anypath Routing for Reducing Latency in Multi-Channel Wireless Mesh Networks

Lavén, Andreas January 2013 (has links)
Increasing capacity in wireless mesh networks can be achieved by using multiple channels and radios. By using different channels, two nodes can send packets at the same time without interfering with each other. To utilize diversity of available frequency, a channel assignment scheme is required. Hybrid channel assignment is an interesting approach where at least one radio is tuned to a fixed channel for receiving and the remaining interfaces switch their channels dynamically in order to match the receiving channel at the receiving node. This provides full connectivity, but at the expense of introduced switching costs. Due to hardware limitations it is too costly to switch channels on a per packet basis. Instead, this thesis proposes an anypath routing and forwarding mechanism in order to allow each node along the route to select the best next hop neighbor on a per packet basis. The routing algorithm finds for each destination a set of next hop candidates and the forwarding algorithm considers the state of the channel switch operation when selecting a next hop candidate. Also, in order to allow latency-sensitive packets to be transmitted before other packets, latency-awareness has been introduced to distinguish e.g. VoIP flows from FTP traffic. The ideas have been implemented and tested using real-world experiments, and the results show a significant reduction in latency.
38

Sentiment analysis in social events

Liu, Qiaoshan January 2018 (has links)
Purpose: The purpose of this study is going to visualize the public sentiment on expected and unexpected social events. Exploring the relationship between tweets forwarding and sentiment. Design/methodology/approach: This research related to sentiment analysis of social events applied a lexicon-based method. The social events come from Facebook data breach and Ireland vote on abortion event. The study conducted This study focused on how the public sentiment changes over time and the relationship between sentiment and tweet forwarding. Bing lexicon and NRC lexicon are adopted in the analysis. Result: The result of this study is the dominant sentiment trend is consistent with the trend of the number of tweets over time in the Facebook data breach and Ireland vote on abortion. Besides, the sentiment has affected people forward tweets in this research.
39

Analýza zasílatelských a kurýrních služeb v ČR / Analysis of Forwarding and Courier Services in Czech Republic

TONCAR, Jiří January 2010 (has links)
Analysis of Forwarding and Courier Services in Czech Republic was carried out fron the end of a service portfolio, quality and cost at the end. The following companies were in a scope of analysis: DHL Express (Czech Republic) s.r.o., FedEx s.r.o., UPS s.r.o., TNT s.r.o., DACHSER EST a.s., Gebrüder Weiss s.r.o., DB Schenker s.r.o.
40

Virtual Routing and Forwarding (VRF) - och dess påverkan på en routers processor

Ohlson, Johan January 2010 (has links)
I dagsläget används VPN allt mer bland företagen för att ansluta till olika nätverk. Detta kan medföra att routingtabellen blir alltför stor och det kan i sin tur påverka processorbelastningen på routern som delar ut alla VPN.Detta arbete hade som syfte att granska om det är några märkbara prestandaskillnader på en routers processor när olika routingprotokoll används tillsammans med VRF. Protokollen som detta arbete tog upp var BGP, OSPF och RIP.Tre olika nätverks-scenarier skapades där olika tester genomfördes för de tre nämnda routingprotokollen. Det gjordes även tester på routrar när ingen VRF användes för att jämföra resultaten. Testerna bestod av att granska processorbelastningen på routrar när det fanns många rutter i nätverket och när nätverket var belastat med trafik.Testernas visade att skillnaden mellan BGP och OSPF inte är särskilt stor, men när RIP användes så steg processorbelastningen markant när nätverket hade många rutter. Om däremot VRF användes tillsammans med RIP så sjönk belastningen avsevärt på vissa routrar.

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