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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

LTE/LTE-Advanced for Vehicular Safety Applications

Soleimani, Hossein 11 July 2018 (has links)
IEEE 802.11p, the known standard for Vehicular Adhoc NETworks (VANETs), suffers from scalability issues and unbounded delay. In addition, the desire to use networks already in existence has created motivation for using cellular networks for vehicular applications. LTE-Advanced is one of the most promising access technologies in the wireless field, providing high data rate, low latency, and a large coverage area. Thus, LTE/LTE-A can be potential access technologies for supporting vehicular applications. Vehicular safety applications are based on broadcasting messages to neighboring vehicles. The vehicle location precision is crucial for safety applications. Thus, the freshness of the information (i.e. vehicle location) at the neighboring vehicles is very important. As LTE is an infrastructure-based network, all transmissions should pass through it. When the load of the network is high compared to the available resources, large delays may occur. The focus of this thesis is to propose solutions to make LTE suitable for vehicular safety applications. The first solution is to adapt the vehicular safety application to be suitable in LTE network. For this purpose, we propose an adaptation of the safety message generation rate. This adaptation uses a queueing model to compute the freshness of the information of vehicles at the destination, based on their message generation rates. It then adjusts the generation periods to provide a similar accuracy for all vehicles. The second approach is to modify the LTE and make it suitable for these kinds of applications. Thus, we proposed a scheduler for LTE which is suitable for vehicular safety applications. It considers the speed and location of the vehicles to allocate the resources to them for the transmission of safety messages. We also studied the message dissemination in the downlink, and proposed an efficient way to deliver the safety messages to the neighboring vehicles. Finally, we propose a scheme that uses both LTE-D2D and LTE-cellular communication for the transmission of safety messages. The centralized location information is used for Device-to-Device (D2D) pair discovery and resource allocation. The proposed scheme provides resource efficiency by enabling the reuse of the resources by vehicles. We also study the effect of the awareness range and period of updating location information at the server on resource usage and accuracy of D2D pair detection.
42

Beacone : En ny BLE beacon med Wi-Fi-stöd för uppdatering av URL / Beacone : A new BLE Beacon with Wi-Fi support for URL update

Fryxelius, Jonathan, Runeson, Johannes January 2017 (has links)
Ända sedan radion uppfanns har trådlös kommunikation varit ett mål för modern teknologi. Trots över 100 års teknologisk utveckling är radiosignaler högst relevanta, och används idag både för traditionell enkelriktad radiosändning, men också som grund för Bluetoothteknologin, som stöds av allt från bilar till telefoner och högtalare. Den här avhandlingen beskriver framtagandet av en speciell typ av Bluetoothsändare, så kallad beacon, som dessutom tillämpar trådlös nätverksanslutning för att utvidga beacons klassiska funktionalitet och ge nya möjligheter. Den nya produkten kallas Beacone. Som stöd för dess funktionalitet utvecklas ett webbgränssnitt och en mobilapplikation. Resultatet utvärderas och möjliga förbättringar diskuteras. Arbetet visar att det under flera omständigheter finns fördelar med en nätverksansluten beacon, som tillhandahåller möjligheter som inte annars hade funnits. / Ever since the invention of the radio, wireless communication has been the goal for modern technology. Despite 100 years of technological development, radio waves remain highly relevant, and are today used both in traditional one-way radio transmission, but also as the foundation for Bluetooth technology, which is supported by cars, phones, speakers, and everything in between. This report describes the development of a special Bluetooth transmitter, a so-called beacon, which also features wireless network connection to expand the traditional functionality of beacons and yield new opportunities. The new product is named Beacone. Supportive software, such as a web interface and a mobile cellphone application, is also developed. The result is evaluated, and possible improvements are discussed. The work shows that there are circumstances where Wi-Fi connectivity provides benefits which would not be available without it.
43

Algoritm för lokalisering av referensnoder med Indoor Positioning System

Abbassi, Selma, Engström, Rickard January 2016 (has links)
Indoor Positioning Systems lokaliserar människor och objekt inomhus med hjälp av minst tre kända referenspunkter. System för inomhuspositionering som använder kända referenspunkter kallas anchor-based lokalisering medan de som beräknar deras positioner själva kallas anchor-free lokalisering. Syftet med detta arbete är att utveckla en algoritm som är anpassad efter ett anchor-free lokaliseringssystem. Den ska vara oberoende av nätverksuppkopplingen, hårdvaran och hur avstånden mellan mottagare och sensorer beräknats. Utgångspunkten för algoritmen är enbart avstånd mellan en mottagare och tre sensorer vilket kan beskrivas som arbetets huvudsakliga problem. Algoritmen implementerades i Java med en simulering som återspeglar positioneringen i en perfekt miljö och sedan testas på en Android-applikation. Simuleringen tillåter användaren att rita ut flera mätpunkter som skapar en rutt. Dessa mätpunkter utnyttjas för att dynamiskt lokalisera referenspunkterna och mätpunkterna genom att hitta ett minsta avstånd mellan sensorerna. Dessa avstånd kan beskrivas som sidorna för en referenstriangel som möjliggör att ett koordinatsystem kan spännas upp. Resultatet av den empiriska studien visade en felmarginal mellan 0,3-6 m utan signalstörningar, vilket inte var tillräckligt noggrant. Efter att algoritmen implementerats lades fokus på en korrigering som kan itereras igenom för att uppskatta bättre mätvärden för referenstriangeln. Korrigeringen gav positiva resultat med lägre felmarginal. Arbetet kan vidareutvecklas genom att implementeras i ett verkligt IPS-system och algoritmen kan förbättras genom att skapa utökade funktioner som kan hantera fler än tre beacons.
44

A COMPOSITE APPROACH TO DEAL WITH LOCALIZATION PROBLEMS IN WIRELESS SENSOR NETWORK

Rao, Shehryar January 2010 (has links)
Universal algorithm approach is very a unique and quite useful. It can be used for most of the localization problems. A number of research studies have been taken to evaluate the different algorithms. The literature review and surveys are the key sources to get the resultant algorithm. This thesis addresses different kind of localization problems and provides a universal solution for these problems. I have done a very important literature review and some industry based surveys. The result of surveys and literature review was a bit same, so it was quite easy to find solution for those similar problems. The idea behind this universal solution is very simple. I chose two algorithms which were quite useful in the localization and merge. The resultant algorithm proves more useful than other two algorithms. The author finds it very healthy and useful algorithm. Moreover, there is need to improve some aspects. There is need to implement this algorithm practically. Some sort of professional skills are required to make this algorithm worthy.
45

WiFi and LTE Coexistence in the Unlicensed Spectrum

Rupasinghe, Nadisanka 26 March 2015 (has links)
Today, smart-phones have revolutionized wireless communication industry towards an era of mobile data. To cater for the ever increasing data traffic demand, it is of utmost importance to have more spectrum resources whereby sharing under-utilized spectrum bands is an effective solution. In particular, the 4G broadband Long Term Evolution (LTE) technology and its foreseen 5G successor will benefit immensely if their operation can be extended to the under-utilized unlicensed spectrum. In this thesis, first we analyze WiFi 802.11n and LTE coexistence performance in the unlicensed spectrum considering multi-layer cell layouts through system level simulations. We consider a time division duplexing (TDD)-LTE system with an FTP traffic model for performance evaluation. Simulation results show that WiFi performance is more vulnerable to LTE interference, while LTE performance is degraded only slightly. Based on the initial findings, we propose a Q-Learning based dynamic duty cycle selection technique for configuring LTE transmission gaps, so that a satisfactory throughput is maintained both for LTE and WiFi systems. Simulation results show that the proposed approach can enhance the overall capacity performance by 19% and WiFi capacity performance by 77%, hence enabling effective coexistence of LTE and WiFi systems in the unlicensed band.
46

Fluorescent Labeling of Antibiotic Resistant Bacteria Model DNA

Darko, Janice 01 August 2018 (has links)
Global threats to treatment of bacterial infections due to antibiotic resistance (AR) have been on the rise in recent years. Current diagnostic tests identify bacteria by using blood culture, which takes more than 24 hours. This study focuses on the fluorescent labeling of DNA derived from bacterial AR genes (KPC & VIM) and other model DNAs using oligreen dye (OG) and molecular beacons (MB). A NanoDrop 3300 fluorospectrometer was used to take fluorescence measurements. Linear dynamic range and labeling efficiency were dependent on the following optimized conditions: dilution factor of OG (200 fold), buffer (20 mM Tris HCl, pH 8), and heat treatment of 95 °C for 15 min.Fluorescence analysis of a target DNA with a designed MB showed signal-to-background of 10 with our buffer only and 20 with our buffer and 25% ethanol. I also demonstrated a simple microfluidic device capable of detecting AR genes using model DNAs, magnetic beads, and designed MBs for assays of µ50 L volume. This study provides a first step towards detecting MB-DNA complexes by a simple, low cost, and fast non-amplified method, which may be used to detect AR genes in clinical samples in the future.
47

Automatic retrieval of data for industrial machines with handheld devices : Positioning in indoor environments using iBeacons

Sjöbro, Linus January 2021 (has links)
Positioning of mobile phones or other handheld devices in indoor environments is hard because it’s often not possible to retrieve a GPS-signal. Therefore, other techniques need to be used for this. Despite the difficulties with indoor positioning, the Swedish mining company LKAB want to do exactly this in their processing plants. LKAB has developed an Apple iPhone mobile application to maintain real-time process data and documents for their machines. To retrieve the information an OCR code need to be manually scanned with the application. Instead of manually scanning these codes, LKAB want to develop an Indoor Positioning System that can automatically locate handheld devices in their production plants. This thesis aimed to create a proof of concept Apple iOS application that can position devices without GPS-signals. In the system developed Bluetooth Low Energy iBeacons is used to transmit data to the application. From this data Received Signal Strength Indication values is collected and sent off to a server that transform the values into positioning fingerprints. These fingerprints are used together with the classification algorithms K-Nearest Neighbour to determine in which, on pre-hand created, group the user is located. In these created groups there is a defined set of machines that is being presented back to the user. Test results conducted with the proof of concept application shows that the implemented system works and gives a positioning accuracy of up to 75%.
48

The Latency Effects of Utilizing a Microservice Architecture in a Time-Critical System

Hölscher, Anton January 2021 (has links)
This study aims to examine the effects of transforming a monolithic server system into a microservice architecture, focusing on the increased latency introduced by using a microservice orchestrator. The microservice orchestrator was implemented using an OpenFlow switch controlled by the Beacon and Ryu OpenFlow controllers. These controllers, along with the round robin, random assign and a server-aware load balancing algorithm, were all compared in order to find the combination resulting in the lowest latency and highest achieved server balance in varying network environments. We show that the OpenFlow switch enforces a client-aware load balancing policy and that only the initial request is handled by the controller, effectively reducing the importance of choosing the optimal OpenFlow controller. In addition, the round robin load balancer was preferred when dealing with homogeneous requests, and a server-aware load balancer was required for heterogeneous requests. For most requests, the system would only slow down by a few microseconds using the proposed architecture. However, for 0.001\% of all requests, the slowdown was much more significant, with each of those requests being at least 100 times slower than when using a monolithic server architecture.
49

Zdroj modulačního signálu pro mikrovlnný maják / Modulation signal source for microwave beacon

Belloň, Michal January 2013 (has links)
This project is focused on construction of source of modulation signal for microwave beacon. The output signal is the same as signal, which is generated by PC software WSJT (Weak Signal by Joe Taylor) on PC sound card output. Signal on device output is modulated using by WSJT modulation and its specific JT4 mode. The device output has I and Q components of signal.
50

Novel Metal Clusters for Imaging Applications

Alsaiari, Shahad K. 05 1900 (has links)
During the past few years, gold nanoparticles (AuNPs) have received considerable attention in many fields due to their optical properties, photothermal effect and biocompatibility. AuNPs, particularly AuNCs and AuNRs, exhibit great potential in diagnostics and imaging. In the present study, AuNCs were used to selectively image and quantify intracellular antioxidants. It was reported by Chen et al. that the strong fluorescence of AuNCs is quenched by highly reactive oxygen species (hROS). Most of applications depend on fluorescence quenching, however, for our project we designed turn-on fluorescent sensors using AuNCs that sense antioxidants. In the presence of antioxidants, AuNCs fluorescence switch on, while in the absence of antioxidants their fluorescence immediately turn off due to hROS effect. AuNRs were also used for cellular imaging in which AuNRs were conjugated to Cy3-labelled molecular beacon (MB) DNA. Next, the previous complex was loaded in two different strains of magnetotactic bacteria (MTB). MTB were used as a targeted delivery vehicle in which magnetosomes direct the movement of bacteria. The DNA sequence was specific to a certain sequence in mitochondria. The exposure of MTB to an alternating magnetic field (AMF) leads to the increase of temperature inside the bacteria, which destruct the cell wall, and hence, bacterial payload is released. When MD-DNA hybrid with the target sequence, AuNR and Cy3 separate from each other, the fluorescence of the Cy3 is restored.

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