Kalendarium
Thesis defence: Dude, Where's My Car? Cellular Navigation for Autonomous Driving
Publicerad: 2024-03-21
Position and direction estimation is useful for numerous engineering applications for commercial, scientific, and military purposes. Technology that fuses observations of signals broadcast by Global Navigational Satellite Systems (GNSS) with inertial measurements is standard for electronic devices, but this requires at least a periodically unobstructed view of the sky to perform reliably. This has motivated the use of terrestrial radio signals as navigation references to complement or as an alternative to satellite systems, but environments with obstructions, specular reflectors, and scatterers of electromagnetic waves create challenges for any wireless navigation system.
This thesis is about how wireless signals other than those transmitted by GNSS might be used for navigation in complex propagation environments, particularly for safety-critical systems, and conversely how position and orientation information can be used to better understand electromagnetic wave propagation. The thesis is split into introductory chapters that provide broad background on the researched subjects, and five papers published in or submitted to scientific conferences and journals.\par
The first paper offers a broad analysis of the requirements for a cellular navigation system to meet the unique and particularly challenging operating requirements of an autonomous vehicle. Aspects of the problem that are not frequently addressed in literature on terrestrial positioning, particularly requirements for safety-critical operation, are included in the analysis. \par
The second, third, and fourth papers propose methods for position estimation for a passenger vehicle operating in a dense urban canyon environment, tested with a specially-designed measurement system that makes passive (opportunistic), high-resolution observations of down-link synchronization signals transmitted by commercial cellular base stations that are paired with highly accurate pose estimates. Inspired by the prominence and success of Artificial Neural Networks (ANNs) in computer vision, ANNs are used for wireless navigation. The results show that meter-level position estimates and accurate heading estimation can be achieved simultaneously when receiving only reflected and scattered signals from a single transmitter that is never within line-of-sight of the receiving antenna array, relying entirely on multipath propagation.
Finally, in the fifth paper, the link between geometry and multipath propagation is explored from a different perspective. Known navigation states are used to study and characterize multipath propagation. A method for multipath component clustering for statistical channel modeling is proposed, where knowledge about the receiver position is used to gain insight into channel statistics. The algorithm is shown to provide consistent results and to be scalable to large data sets.
Link to thesis i LU Research Portal:
Zoom link. Zoom ID: 69963010473.
När: | 2024-04-10 09:15 till 2024-04-10 13:00 |
Plats: | E-house, E:1406. |
Kontakt: | russell.whiton@eit.lth.se |
Thesis defence: Computational Methods and Measurements for Direct and Inverse Scattering of Microwaves
Publicerad: 2024-03-18
The problem of electromagnetic scattering has long been important in radar, where it is the mechanism for detection. This is often called the direct scattering problem, where a known object is illuminated by an incident wave and the scattered wave is computed. In Paper I, a computational code implementing the finite element-boundary integral method is presented. The code, which is publicly available at https://www.github.com/nwingren/fe2ms, was developed using open-source software to accelerate the development process. While this code is verified in Paper I, there were no comparisons to measurements. In Paper II, a complete design process was performed using the code from Paper I, with manufacturing using 3D printing and measurements of the performance to validate the computations. This acted both as a demonstration of using the code practically, and as a validation. One advantage of the finite element-boundary integral method used in the code is that problems with highly complex media can be solved. This was utilized in Paper III where characteristic modes were computed for a an inhomogeneous, bianisotropic, and nonreciprocal object.
A different problem is that of inverse scattering, for which the scattered wave is known but the object or incident wave is unknown. This is a more complicated problem which requires the modern computational methods available today, and can be used to discern properties of an object, for example for nondestructive testing. In Paper IV, a method for nondestructive testing of singly curved composite panels using millimeter waves is presented together with measurements of real panels. The method is based on computational electromagnetics and was designed specifically for detection of sparsely distributed flaws in such panels. Microwaves and millimeter waves are relatively new in nondestructive testing compared to other methods like ultrasound. One possible development would be to combine the new and the old by utilizing interaction between acoustic and electromagnetic waves. As a way to demonstrate that this might be possible, microwaves scattered by ultrasound were measured in Paper V in air, where the interaction would be much weaker than in nondestructive testing settings.
Link to thesis i LU Research Portal:
Zoom link. Zoom ID: 62684643819.
När: | 2024-04-05 09:15 till 2024-04-05 13:00 |
Plats: | E-house, E:1406. |
Kontakt: | niklas.wingren@eit.lth.se |
An inclusive work environment - Norm awareness in practice
Publicerad: 2024-02-26
The workshop combines basic theory with humour, practical exercises and everyday examples of how different norms affect our treatment of each other. The different grounds for discrimination are linked together and you will gain knowledge about how they interact and the mechanisms that lie behind and create inequality.
We all have different experiences and values that affect how we treat each other - often unconsciously. This workshop aims wants to stimulate people's desire to change because they themselves feel that they are developing, not because someone else demands it. This requires a large portion of humour and humility. It is about creating inspiration and seeing things outside your own normative bubble. We all have a lot to gain from counteracting prejudices and seeing the norms that exist in our workplaces.
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Mingle after the workshop: Coffee and cake will be served in the foyer.
Registration is not needed but will be appreciated. Please use this link ?? https://www.eit.lth.se/ws-jamstallt
När: | 2024-03-12 13:15 till 2024-03-12 14:45 |
Plats: | E-house, E:A |
Kontakt: | kaan.bur@eit.lth.se |
Thesis defence: Navigating the Future: Intersection of Safety, Efficiency, and Resilience in Autonomous Traffic Systems
Publicerad: 2024-02-29
This thesis embarks on a journey in the advancement of urban traffic management, centering around the innovative integration of Autonomous Intersection Management (AIM) systems. The research encompasses a comprehensive exploration of various facets of AIM implementation, significantly contributing to the evolution of a more efficient and safer urban transport system.
The research investigates the dynamic and complex environment of city transportation, addressing the myriad of challenges and opportunities that arise with the advancement of autonomous vehicle technology. It synthesizes a broad spectrum of dimensions in AIM implementation, collectively contributing to the vision of a more streamlined and safer urban transportation network.
A pivotal aspect of this thesis is the exploration of the interplay between autonomous and non-autonomous vehicles in urban settings. The study assesses the robustness and resilience of AIM systems across diverse and unpredictable scenarios, with a focus on adaptive control strategies, wireless communication challenges, and efficient traffic flow management. This emphasis highlights the crucial role of these systems in ensuring safety and efficiency, especially in mixed-traffic environments.
A notable contribution of this work is the integration of cutting-edge technologies like machine learning with AIM, proposing innovative solutions for traffic management. These solutions are designed to reduce operational complexities and enhance scalability, showcasing potential to transform traditional traffic management practices. This aspect of the research not only demonstrates innovation but also practical applicability in urban contexts.
The thesis culminates in demonstrating the practical application and effectiveness of AIM systems in real-world urban contexts. Besides underscoring the relevance and utility of the research, it also showcases the practical applicability of the model. The findings and developments presented in this work pave the way for future advancements in the field.
In summary, this thesis offers a substantial contribution to urban transportation management by providing innovative insights and practical solutions for the integration and optimization of AIM systems. It lays a foundational framework for future research, steering towards advanced transportation networks, which are both safe and efficient.
Link to thesis i LU Research Portal:
https://portal.research.lu.se/en/publications/navigating-the-future-intersection-of-safety-efficiency-and-resil
Zoom link. Zoom ID: 66179207826.
När: | 2024-03-12 09:15 till 2024-03-12 13:00 |
Plats: | E-house, E:1406. |
Kontakt: | seyedezahra.chamideh@eit.lth.se |
Thesis defence: Ferroelectric memristors: materials, interfaces and applications
Publicerad: 2024-02-28
The backbone of modern computing systems rely on two key things: logic and memory, and while computing power has
seen tremendous advancements through scaling of the fundamental building block ? the transistor, memory access hasn?t
evolved as rapidly, leading to significant memory-bound systems. Additionally, the rapid evolution of machine learning
and deep neural network (DNN) applications, has exposed the fundamental limitations of the traditional von Neumann
computing architecture, due to its heavy reliance on memory access. The physical separation between the computing unit
and the memory in von Neumann architectures is limiting performance and energy efficiency. A promising solution to
address these challenges is the development of emerging non-volatile memory technologies that provide significant scaling
and integration possibilities, fast switching speeds, and highly energy-efficient operations. Additionally, by integrating
?memory resistors? (memristors) in large crossbar arrays, the computation can take place in-memory which can resolve the
bottleneck in traditional von Neumann architectures.
This thesis investigates the implementation of ferroelectric HfO2 in ferroelectric tunnel junctions (FTJs) and ferroelectric
field effect transistors (FeFETs) as potential candidates for emerging non-volatile memories and memristors.
Initially, the thesis focuses on the integration of ferroelectric HfO2 onto the high mobility III-V semiconductor InAs for
the fabrication of metal-oxide-semiconductor (MOS) capacitors. Moreover, optimization of the processing conditions on the
critical interface between the semiconductor and high-k oxide is extensively studied using both electrical characterization and
synchrotron radiation techniques. After optimization of the annealing treatment and top electrode texturing, the fabrication
of vertical InAs nanowire FeFETs is successfully implemented. The FeFET shows encouraging initial results with limitations
solvable by further process engineering.
Link to thesis i LU Research Portal:
Zoom link. Zoom ID: 63504410836
När: | 2024-03-08 09:15 till 2024-03-08 13:00 |
Plats: | E-house, E:1406. |
Kontakt: | robin.atle@eit.lth.se |
Thesis defence: III-V Devices for Emerging Electronic Applications
Publicerad: 2024-02-05
Today?s digitalized society relies on the advancement of silicon (Si) Complementary Metal Oxide Semiconductor (CMOS) technology, but the limitations of down-scaling and the rapidly increasing demand for added functionality that is not easily achieved in Si, have pushed efforts to monolithically 3D-integrate III-V devices above the Si-CMOS technology. In addition, the demand for increased computational power and handling of vast amounts of data is rapidly increasing. This has led to an increased interest in quantum computing, offering the potential to solve specific complex problems more efficiently than conventional computers. Superconducting transmon Quantum Bits (qubits) are promising for the realization of quantum computers, which has led to an increased interest in cryogenic electronics. For these applications, III-Vs are suitable as their high carrier mobility enables low power consumption, low noise, and highly transparent superconductor-semiconductor interfaces. High-quality interfaces between superconductors and semiconductors are crucial for the implementation of gate-tunable hybrid superconductor-semiconductor qubits known as gatemon qubits.
This thesis explores the potential of utilizing indium arsenide (InAs) and indium gallium arsenide (InGaAs) nanowire and quantum well devices in these emerging electronic applications. Both as an add-on in Si-CMOS technology, as well as the channel material in electronic devices for cryogenic applications.
The electron transport in near surface quantum wells is studied by DC-measurements in combination with applied magnetic fields, from room temperature down to cryogenic temperatures. Several different ways to extract the carrier mobility are investigated, such as standard current-voltage sweeps, the Geometrical Magnetoresistance Effect (gMR), as well as the Hall effect. A deeper understanding of electron transport at cryogenic temperatures is obtained by the development of a model for the current characteristics of long-channel InGaAs quantum well Metal-Oxide Semiconductor Field-Effect Transistors (MOSFETs), which includes the effects of band tail states, electron concentration-dependent mobility, and interface trap density. The model shows an increased effect of remote impurity scattering associated with mobility degradation in the subthreshold region.
A demultiplexer based on an InGaAs nanowire network was fabricated, to enable routing of DC-currents on-chip and reduce the number of connections to the cryostat. To facilitate system-level investigation of circuits containing Josephson Field-Effect Transistors (JoFETs), a compact model was developed which by circuit simulations accurately reproduced the measured data from our JoFET.
Finally, a process for the growth of InAs nanowires on tungsten was developed. This novel approach is based on Template-Assisted Selective Epitaxy (TASE) and allows for easy 3D-integration of III-V devices in Si-CMOS technology.
Link to thesis i LU Research Portal:
https://portal.research.lu.se/en/publications/iii-v-devices-for-emerging-electronic-applications
När: | 2024-02-23 09:15 till 2024-02-23 13:00 |
Plats: | E-house, E:1406. |
Kontakt: | patrik.olausson@eit.lth.se |