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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

Improved TDOA/AOA Position Location for Indoor UWB Systems

Yeh, Yi-Ching 25 August 2005 (has links)
Accurate indoor geolocation is an important and novel emerging technology for commercial, public safety, and military applications. Since most wireless communication systems used for indoor position location may suffer from dense multipath situation, which leads to a severe degradation of position accuracy. The improved TDOA/AOA(Time Difference of Arrival/ Angle of Arrival) position location for indoor ultra-wide band (UWB) systems in the thesis improves the position accuracy of indoor location by using fine resolution of UWB signals. In the line of sight situation, by means of increasing angle of arrival (AOA) information to time difference of arrival (TDOA) based location to achieve the goal of accurate indoor geolocation and provides non-line of sight (NLOS) error mitigation for time measurement and AOA selection to suppress the impact to position accuracy in NLOS environment. Finally, the extended Kalman filter is used to perform position tracking of the target. In the simulations, the NLOS error in time measurement is produced according to the characteristics of indoor UWB channel. Several assumptions of NLOS errors are made in angular measurement. It is observed that proposed method efficiently mitigates the position error in NLOS environment, and detect if the NLOS exists between base station and mobile station immediately.
2

Quantum computers for nuclear physics

Yusf, Muhammad F 08 December 2023 (has links) (PDF)
We explore the paradigm shift in quantum computing and quantum information science, emphasizing the synergy between hardware advancements and algorithm development. Only now have the recent advances in quantum computing hardware, despite a century of quantum mechanics, unveiled untapped potential, requiring innovative algorithms for full utilization. Project 1 addresses quantum applications in radiative reactions, overcoming challenges in many-fermion physics due to imaginary time evolution, stochastic methods like Monte Carlo simulations, and the associated sign problem. The methodology introduces the Electromagnetic Transition System and a general two-level system for computing radiative capture reactions. Project 2 utilizes Variational Quantum Eigensolver (VQE) to address the difficulties in adiabatic quantum computations, highlighting Singular Value Decomposition (SVD) in quantum computing. Results demonstrate an accurate ground state wavefunction match with only a 0.016% energy error. These projects advance quantum algorithm design, error mitigation, and SVD integration, showcasing quantum computing’s transformative potential in computational science.
3

Low Overhead Soft Error Mitigation Methodologies

Prasanth, V January 2012 (has links) (PDF)
CMOS technology scaling is bringing new challenges to the designers in the form of new failure modes. The challenges include long term reliability failures and particle strike induced random failures. Studies have shown that increasingly, the largest contributor to the device reliability failures will be soft errors. Due to reliability concerns, the adoption of soft error mitigation techniques is on the increase. As the soft error mitigation techniques are increasingly adopted, the area and performance overhead incurred in their implementation also becomes pertinent. This thesis addresses the problem of providing low cost soft error mitigation. The main contributions of this thesis include, (i) proposal of a new delayed capture methodology for low overhead soft error detection, (ii) adopting Error Control Coding (ECC) for delayed capture methodology for correction of single event upsets, (iii) analyzing the impact of different derating factors to reduce the hardware overhead incurred by the above implementations, and (iv) proposal for hardware software co-design for reliability based upon critical component identification determined by the application executing on the hardware (as against standalone hardware analysis). This thesis first surveys existing soft error mitigation techniques and their associated limitations. It proposes a new delayed capture methodology as a low overhead soft error detection technique. Delayed capture methodology is an enhancement of the Razor flip-flop methodology. In the delayed capture methodology, the parity for a set of flip-flops is calculated at their inputs and outputs. The input parity is latched on a second clock, which is delayed with respect to the functional clock by more than the soft error pulse width. It requires an extra flip-flop for each set of flip-flops. On the other hand, in the Razor flip-flop methodology an additional flip-flop is required for every functional flip-flop. Due to the skew in the clocks, either the parity flip-flop or the functional flip-flop will capture the effect of transient, and hence by comparing the output parity and latched input parity an error can be detected. Fault injection experiments are performed to evaluate the bneefits and limitations of the proposed approach. The limitations include soft error detection escapes and lack of error correction capability. Different cases of soft error detection escapes are analyzed. They are attributed mainly to a Single Event Upset (SEU) causing multiple flip-flops within a group to be in error. The error space due to SEUs is analyzed and an intelligent flip-flop grouping method using graph theoretic formulations is proposed such that no SEU can cause multiple flip-flops within a group to be in error. Once the error occurs, leaving the correction aspects to the application may not be desirable. The proposed delayed capture methodology is extended to replace parity codes with codes having higher redundancy to enable correction. The hardware overhead due to the proposed methodology is analyzed and an area savings of about 15% is obtained when compared to an existing soft error mitigation methodology with equivalent coverage. The impact of different derating factors in determining the hardware overhead due to the soft error mitigation methodology is then analyzed. We have considered electrical derating and timing derating information for the evaluation purpose. The area overhead of the circuit with implementation of delayed capture methodology, considering different derating factors standalone and in combination is then analyzed. Results indicate that in different circuits, either a combination of these derating factors yield optimal results, or each of them considered standalone. This is due to the dependency of the solution on the heuristic nature of the algorithms used. About 23% area savings are obtained by employing these derating factors for a more optimal grouping of flip-flops. A new paradigm of hardware software co-design for reliability is finally proposed. This is based on application derating in which the application / firmware code is profiled to identify the critical components which must be guarded from soft errors. This identification is based on the ability of the application software to tolerate certain errors in hardware. An algorithm to identify critical components in the control logic based on fault injection is developed. Experimental results indicated that for a safety critical automotive application, only 12% of the sequential logic elements were found to be critical. This approach provides a framework for investigating how software methods can complement hardware methods, to provide a reduced hardware solution for soft error mitigation.
4

Ranging Error Correction in a Narrowband, Sub-GHz, RF Localization System / Felkorrigering av avståndsmätingar i ett narrowband, sub-GHz, RF-baserat positioneringssystem

Barrett, Silvia January 2023 (has links)
Being able to keep track of ones assets is a very useful thing, from avoiding losing ones keys or phone to being able to find the needed equipment in a busy hospital or on a construction site. The area of localization is actively evolving to find the best ways to accurately track objects and devices in an energy efficient manner, at any range, and in any type of environment. This thesis focuses on the last aspect of maintaining accurate localization regardless of environment. For radio frequency based systems, challenging environments containing many obstacles, e.g., indoor or urban areas, have a detrimental effect on the measurements used for positioning, making them deceptive. In this work, a method for correcting range measurements is proposed for a narrowband sub-GHz radio frequency based localization system using Received Signal Strength Indicator (RSSI) and Time-of-Flight (ToF) measurements for positioning. Three different machine learning models were implemented: a linear regressor, a least squares support vector machine regressor and a gaussian process regressor. They were compared in their ability to predict the true range between devices based on raw range measurements. Achieved was a 69.96 % increase in accuracy compared to uncorrected ToF estimates and a 88.74 % increase in accuracy compared to RSSI estimates. When the corrected range estimates were used for positioning with a trilateration algorithm using least squares estimation, a 67.84 % increase in accuracy was attained compared to positioning with uncorrected range estimates. This shows that this is an effective method of improving range estimates to facilitate more accurate positioning. / Att kunna hålla reda på var ens tillgångar befinner sig kan vara mycket användbart, från att undvika att ens nycklar eller telefon tappas bort till att kunna hitta utrustningen man behöver i ett myllrande sjukhus eller på en byggarbetsplats. Området av lokalisering utvecklas aktivt för att hitta de bästa metoderna och teknologierna för att med precision kunna spåra fysiska objekt på ett energieffektivt sätt, på vilken räckvidd som helst, och i vilken miljö som helst. Detta arbete fokuserar på den sista aspekten av att uppnå precis positionering oavsett miljö. För radiofrekvensbaserade system har utmanande miljöer med många fysiska hinder som till exempel inomhus och stadsområden en negativ effekt på de mätningar som används för positionering, vilket gör dem vilseledande. I detta arbete föreslås en metod för att korrigera avståndsmätningar i ett narrowband sub-GHz radiofrekvensbaserat lokaliseringssystem som använder Received Signal Strength Indicator (RSSI)- och Time-of-Flight (ToF)-mätningar för positionering. Tre olika maskininlärningsmodeller har implementerats: en linear regressor, en least squares support vector machine regressor och en gaussian process regressor. Dessa jämfördes i sin förmåga att förutspå det sanna avståndet mellan enheter baserat på råa avståndsmätningar. De korrigerade avståndsmätningarna uppnådde 69.96 % högre nogrannhet jämfört med okorrigerade ToF-uppskattningar och 88.74 % högre nogrannhet jämfört med RSSI-uppskattningar. Avståndsuppskattningarna användes för positionering med trilateration och minsta kvadratmetoden. De korrigerade uppskattningarna gav 67.84 % mer precis positionering jämfört med de okorrigerde uppskattningarna. Detta visar att detta är en effektiv metod förbättra avståndsuppskattningarna för att i sin tur bidra till mer exakt positionering.
5

Design and Development of a CubeSat Hardware Architecture with COTS MPSoC using Radiation Mitigation Techniques

Vasudevan, Siddarth January 2020 (has links)
CubeSat missions needs components that are tolerant against the radiation in space. The hardware components must be reliable, and it must not compromise the functionality on-board during the mission. At the same time, the cost of hardware and its development should not be high. Hence, this thesis discusses the design and development of a CubeSat architecture using a Commercial Off-The- Shelf (COTS) Multi-Processor System on Chip (MPSoC). The architecture employs an affordable Rad-Hard Micro-Controller Unit as a Supervisor for the MPSoC. Also, it uses several radiation mitigation techniques such as the Latch-up protection circuit to protect it against Single-Event Latch-ups (SELs), Readback scrubbing for Non- Volatile Memories (NVMs) such as NOR Flash and Configuration scrubbing for the FPGA present in the MPSoC to protect it against Single-Event Upset (SEU)s, reliable communication using Cyclic Redundancy Check (CRC) and Space packet protocol. Apart from such functionalities, the Supervisor executes tasks such as Watchdog that monitors the liveliness of the applications running in the MPSoC, data logging, performing Over-The-Air Software/Firmware update. The thesis work implements functionalities such as Communication, Readback memory scrubbing, Configuration scrubbing using SEM-IP, Watchdog, and Software/Firmware update. The execution times of the functionalities are presented for the application done in the Supervisor. As for the Configuration scrubbing that was implemented in Programmable Logic (PL)/FPGA, results of area and latency are reported. / CubeSat-uppdrag behöver komponenter som är toleranta mot strålningen i rymden. Maskinvarukomponenterna måste vara pålitliga och funktionaliteten ombord får inte äventyras under uppdraget. Samtidigt bör kostnaden för hårdvara och dess utveckling inte vara hög. Därför diskuterar denna avhandling design och utveckling av en CubeSatarkitektur med hjälp av COTS (eng. Custom-off-The-Shelf) MPSoC (eng. Multi Processor System-on-Chip). Arkitekturen använder en prisvärd strålningshärdad (eng. Rad-Hard) Micro-Controller Unit(MCU) som Övervakare för MPSoC:en och använder också flera tekniker för att begränsa strålningens effekter såsom kretser för att skydda kretsen från s.k. Single Event Latch-Ups (SELs), återläsningsskrubbning för icke-volatila minnen (eng. Non-Volatile Memories) NVMs som NOR Flash och skrubbning av konfigurationsminnet skrubbning för FPGA:er i MPSoC:en för att skydda dem mot Single-Event Upsets (SEUs), och tillhandahålla pålitlig kommunikation mha CRC och Space Packet Protocol. Bortsett från sådana funktioner utför Övervakaren uppgifter som Watchdog för att övervaka att applikationerna som körs i MPSoC:en fortfarande är vid liv, dataloggning, och Over- the-Air-uppdateringar av programvaran/Firmware. Examensarbetet implementerar funktioner såsom kommunikation, återläsningsskrubbning av minnet, konfigurationsminnesskrubbning mha SEM- IP, Watchdog och uppdatering av programvara/firmware. Exekveringstiderna för utförandet av funktionerna presenteras för den applikationen som körs i Övervakaren. När det gäller konfigurationsminnesskrubbningen som implementerats i den programmerbara logiken i FPGA:n, rapporteras area och latens.

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