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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

Implementation of Sub-GHz Real Time Radio

Åstrand, Lisa January 2016 (has links)
The field of automation and smart devices is currently expanding. As most devices require wireless communication, the market for low budget, low power radios is growing rapidly. Many applications, such as the remote control of machines, have real time requirements with minimal latency. In this report, the market of wireless chips in the sub-GHz region has been investigated in order to give Syntronic AB an insight of the current market. Several key features such as range, data rate and output power were ranked among the available chips. To provide Syntronic with a marketing tool when reaching out to customers in the remote control field, a demonstration prototype (demo) was implemented using one of the radio chips from the list. The demo shows real time requirements with low latency between two wireless nodes. The first node takes movement data from a computer mouse and transmits it to the other node controlling an array of light emitting diodes (LEDs). This report contains the selection of radio configurations, design of a new wireless communications protocol, and implementation of the system in hardware and software. Measurements show a latency of 3.6 ms and a range of approximately 450 m which is regarded satisfactory.
2

Impairment Mitigation in High Capacity and Cost-efficient Optical Data Links

Iglesias Olmedo, Miguel January 2017 (has links)
The work presented in this thesis fits within the broader area of fiber optics communications. This is an important area of research as it provides a breeding ground for the present and future technologies supporting the Internet. Due to the ever-increasing bandwidth demands worldwide, the network infrastructures that make up the Internet are continuously being upgraded. This thesis aims to identify key segments of the Internet that are deemed to become the Internet's bottleneck if new technology does not replace the current one. These are datacenter intra and inter-connects, and metropolitan core area networks. In each category, we provide a comprehensive overview of the state of the art, identify key impairments affecting data transmission, and suggest solutions to overcome them.   For datacenter intra and inter-connects, the key impairments are lack of bandwidth from electro-optic devices, and dispersion. Solutions attempting to tackle these impairments must be constrained by cost and power consumption. The provided solution is MultiCAP, an alternative advanced modulation format that is more tolerable to dispersion and provides bandwidth management features, while being flexible enough to sacrifice performance in order to gain simplicity. MultiCAP was the first advanced modulation format to achieve over 100~Gb/s in 2013 for a data-center interconnect and set the world record on data transmission over a single VCSEL in 2014 for a short reach data link.    On metro-core networks, the challenge is to efficiently mitigate carrier induced frequency noise generated by modern semiconductor lasers. We point out that, when such lasers are employed, the commonly used laser linewidth fails to estimate system performance, and we propose an alternative figure of merit we name "Effective Linewidth". We derive this figure of merit analytically, explore it by numerical simulations and experimentally validate our results by transmitting a 28~Gbaud DP-16QAM over an optical link. / <p>QC 20170602</p> / GRIFFON
3

Issues in Assessing Short-Term Water Supply Capabilities of Reservoir Systems

Schnier, Spencer Thomas 2010 May 1900 (has links)
The Texas Commission on Environmental Quality (TCEQ) uses a Water Availability Modeling System (WAM) to support long-term regional and statewide water resources planning and management. The water availability studies are based on the modeling capabilities of the Water Rights Analysis Package (WRAP). This research improves the understanding of decision support tools for short-term river basin management. Current reservoir storage levels must be considered to assess short-term frequencies and reliabilities. Conditional reliability modeling (CRM) is used to assess the likelihood of meeting targets for instream flow, reservoir storage, water supply diversion and hydroelectric power generation in the near future (next month to next several years), conditioned upon preceding storage. This study uses data for the Brazos River Basin from the TCEQ WAM System to assess key complexities of water supply reliability analysis in general and conditional reliability modeling in particular. These complexities include uncertainties associated with river basin hydrology, estimating yield-reliability relationships for individual reservoirs and multiple reservoir systems, conventional long-term planning versus short-term adaptive management and other modeling and analysis issues. The modeling capabilities of WRAP were expanded to support near real-time operation of dams under various stream flow conditions. The sensitivity to changes in modeling options is assessed for short and long-term simulations. Traditional and newly developed methodologies for estimating firm yields and water supply reliabilities are evaluated. Guidelines are developed regarding the practical application of firm yield analyses and conditional reliability modeling. Important applications of this research include real-time decision support during drought and routinely recurring operational planning activities. A case study of the drought of 2009 uses the CRM features of WRAP for these applications.
4

Self referencing SPR sensor by simultaneous excitation of long and short range surface plasmon modes

Donipudi, Raghunandan K 01 January 2006 (has links)
A novel surface plasmon resonance sensor is fabricated to evaluate its use in biochemical sensing. The sensor can differentiate between bulk refractive index changes and surface binding reactions of interest. There has been a great interest in developing sensors to differentiate biological or chemical agents from interfering effects, but they still remain in research phase. In this work, a prism coupler is used to simultaneously excite both long and short range surface plasmon modes of the sensor. The differing sensitivities of the long and short range modes allow one to distinguish surface binding reactions of interest from refractive index fluctuations. In this thesis, we have demonstrated the sensors self referencing capability by detecting the formation of an octadecanethiol self assembled monolayer while varying solution refractive index.
5

A multi-model ensemble system for short-range weather prediction in South Africa

Landman, Stephanie 06 February 2012 (has links)
Predicting the location and timing of rainfall events has important social and economic impacts. It is also important to have the ability to predict the amount of rainfall accurately. In operational centres forecasters use deterministic model output data as guidance for a subjective probabilistic rainfall forecast. The aim of this research is to determine the skill in an objective multi-model, multi-institute objective probabilistic forecast system. This was done by obtaining the rainfall forecast of two high-resolution regional models operational in South Africa. The first model is the Unified Model (UM) which is operational at the South African Weather Service. The UM contributed three members which differ in physics, data assimilation techniques and horisontal resolution. The second model is the Conformal-Cubic Atmospheric Model (CCAM) which is operational at the Council for Scientific and Industrial Research which in turn contributed two members to the ensemble system differing in horisontal resolution. A single-model ensemble was constructed for the UM and CCAM models respectively with each of the individual members having equal weights. The UM and CCAM single-model ensemble prediction models have been used in turn to construct a multi-model ensemble prediction system, using simple un-weighted averaging. The multi-model system was used to predict the 24-hour rainfall totals for three austral summer half-year seasons of 2006/07 to 2008/09. The forecast of this system was rigorously tested using observed rainfall data for the same period. From the multi-model system it has been found that the probabilistic forecast has good significant skill in predicting rainfall. The multi-model system proved to have skill and shows discrimination between events and non-events. This study has shown that it is possible to make an objective probabilistic rainfall forecast by constructing a multi-model, multi-institute system with high resolution regional models currently operational in South Africa. Thus, probabilistic rainfall forecasts with usable skill can be made with the use of a multi-model short-range ensemble prediction system over the South African domain. Such a system is not currently operational in South Africa. Copyright / Dissertation (MSc)--University of Pretoria, 2012. / Geography, Geoinformatics and Meteorology / Unrestricted
6

An investigation of the propagation characteristics of a single frequency mid-latitude NVIS radio channel

Burgess, Samuel J. January 1999 (has links)
No description available.
7

A Study of the Relationship between the Intensity of Short-Range and Medium-Range Capacity Management and the Effectivenesss of Manufacturing Operations

Yehudai, Joseph 05 1900 (has links)
The objective of this study was to examine the relationship between intensity of short-range and medium-range capacity management and effectiveness of manufacturing operations. Data were collected to test the null hypothesis which stated that intensity of short-range and medium-range capacity management does not influence manufacturing effectiveness. Intensity of short-range and medium-range capacity management was indicated by the following variables: (1) production standards; (2) priority determination; (3) delivery dates determination; (4) material requirements planning; (5) routing information; (6) capacity utilization; and (7) backlog measurement. Manufacturing effectiveness was indicated by the following variables: (1) delivery dates performance; (2) lead times; (3) subcontract work; (4) direct labor overtime; (5) direct labor efficiency; (6) plant and equipment utilization; and (7) work in process inventory. The population selected to provide data for this study is the manufacturing firms in the State of Texas with five hundred or more employees. Over 42 percent of the eligible firms responded to a six-page questionnaire. Several multivariate techniques were utilized for data analysis: (1) factor analysis; (2) canonical correlation analysis; (3) bivariate correlation; (4) multiple linear regression; (5) cross-tabulation; and (6) analysis of variance. The results of this research did not adequately support the rejection of the null hypothesis. However, they did definitely identify a distinct group of capacity management intensity variables that influence manufacturing effectiveness in specific cases. Intensity variables were placed in three groups that identified how influential they were over the effectiveness measures. The most influential group included the variables: production standards and material requirements planning. The indication for the manufacturing manager is to concentrate on improvements in these areas. Effectiveness variables were also placed in three groups that identified the level at which the variables were influenced by the intensity variables. The highly influenced group included plant and equipment utilization and delivery dates performance.
8

Evaluation of Wireless Techniques for Short-Range Communication / Utvärdering av trådlösa tekniker för kommunikation över korta avstånd

Söderkvist, Jonas January 2003 (has links)
<p>On radar level gauges currently shipped by Saab Rosemount, some adjustments of the unit's parameters has to be performed in the field. Presently, this is a cumbersome procedure; the operator has to be very close to the gauge and he either has to carry with him a bulky configuration unit or use a basic control unit on the gauge. A wireless solution, where a portable device and a receiver replace the control unit, would both allow the operator to work from a distance and eliminate the need for the bulky device. </p><p>The most conspicuous restraint for such a solution is a very low allowed power dissipation. The reason for this is that some gauges do not have a separate power supply, but are fed directly off the communication bus. A viable solution should also be commercially available and robust enough to operate in an industrial environment. </p><p>To meet these requirements both a theoretical and a practical assessment was conducted, where the two techniques for wireless communication, IrDA, and Bluetooth, was given special consideration. As for the portable device, the market for hand-held computers was investigated and ultimately a PDA from Palm was selected for this project. Together with this PDA, a prototype for each of the two wireless techniques was tested to ascertain their performance with respect to power dissipation, communication range, and communication robustness. </p><p>This investigation revealed that Bluetooth could be used over a much greater distance than IrDA and it did also provide a more robust solution overall. IrDA is nonetheless also a competent technique, and has its primary advantage in terms of much lower power dissipation compared to Bluetooth.</p>
9

QoS Evaluation of BandwidthSchedulers in IPTV Networks OfferedSRD Fluid Video Traffic

Mondal, Chandra Shekhar January 2009 (has links)
Internet protocol TV (IPTV) is predicted to be the key technology winner in the future. Efforts to accelerate the deployment of IPTV centralized model which is combined of VHO, encoders, controller, access network and Home network. Regardless of whether the network is delivering live TV, VOD, or Time-shift TV, all content and network traffic resulting from subscriber requests must traverse the entire network from the super-headend all the way to each subscriber's Set-Top Box (STB).IPTV services require very stringent QoS guarantees When IPTV traffic shares the network resources with other traffic like data and voice, how to ensure their QoS and efficiently utilize the network resources is a key and challenging issue. For QoS measured in the network-centric terms of delay jitter, packet losses and bounds on delay. The main focus of this thesis is on the optimized bandwidth allocation and smooth datatransmission. The proposed traffic model for smooth delivering video service IPTV network with its QoS performance evaluation. According to Maglaris et al [5] First, analyze the coding bit rate of a single video source. Various statistical quantities are derived from bit rate data collected with a conditional replenishment inter frame coding scheme. Two correlated Markov process models (one in discrete time and one incontinuous time) are shown to fit the experimental data and are used to model the input rates of several independent sources into a statistical multiplexer. Preventive control mechanism which is to be include CAC, traffic policing used for traffic control.QoS has been evaluated of common bandwidth scheduler( FIFO) by use fluid models with Markovian queuing method and analysis the result by using simulator andanalytically, Which is measured the performance of the packet loss, overflow and mean waiting time among the network users.
10

QoS evaluation of Bandwidth Schedulers in IPTV Networks Offered SRD Fluid Video Traffic

Habib, Mohammad Ahasan January 2009 (has links)
Internet protocol TV (IPTV) is predicted to be the key technology winner in the future. Efforts to accelerate the deployment of IPTV centralized model which is combined of VHO, encoders, controller, access network and Home network. Regardless of whether the network is delivering live TV, VOD, or Time-shift TV, all content and network traffic resulting from subscriber requests must traverse the entire network from the super-headend all the way to each subscriber's Set-Top Box (STB). IPTV services require very stringent QoS guarantees When IPTV traffic shares the network resources with other traffic like data and voice, how to ensure their QoS and efficiently utilize the network resources is a key and challenging issue. For QoS measured in the network-centric terms of delay jitter, packet losses and bounds on delay. The main focus of this thesis is on the optimized bandwidth allocation and smooth data transmission. The proposed traffic model for smooth delivering video service IPTV network with its QoS performance evaluation. According to Maglaris et al [5] first, analyze the coding bit rate of a single video source. Various statistical quantities are derived from bit rate data collected with a conditional replenishment inter frame coding scheme. Two correlated Markov process models (one in discrete time and one in continuous time) are shown to fit the experimental data and are used to model the input rates of several independent sources into a statistical multiplexer. Preventive control mechanism which is to be including CAC, traffic policing used for traffic control. QoS has been evaluated of common bandwidth scheduler( FIFO) by use fluid models with Markovian queuing method and analysis the result by using simulator and analytically, Which is measured the performance of the packet loss, overflow and mean waiting time among the network users.

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