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Characterisation of recycled plastics for automotive radar applications at 77 GHz
(2024) Ameerudeen, Mohamed Azad; Nourjoo, Mohammad; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap (MC2); Chalmers University of Technology / Department of Microtechnology and Nanoscience (MC2); Stake, Jan; Bevilacqua, Stella; Tell, Sara; Vakili, Iman
This work investigates the potential of various recycled plastic materials for use in bumper areas which are in closer proximity to automotive radar systems operating at 77 GHz. The study focuses on both experimental and analytical calculation approaches to assess the electromagnetic properties of these materials, specifically focusing on their complex permittivity and loss tangent characteristics at 77 GHz. For this purpose, a quasi-optical measurement setup which utilises metallic reflective mirrors to narrow and collimate the beam of waves produced by WR12 frequency extenders in the 65-90 GHz range is used. The S-parameters measured by the Vector Network Analyzer (VNA) of the samples are utilised to calculate the complex refractive index. This procedure allows for the determination of the permittivity and loss tangent for each specific sample material. To ensure the robustness of the calculation method, the known permittivity and loss tangent values at 77 GHz from a reference non-recycled material provided by the supplier are utilised to calculate theoretical S-parameters, which are then employed in the same method to re-evaluate the permittivity and loss tangent. This process enables a direct comparison with the initial VNA-derived results. This round-trip verification process confirms the reliability of the calculation method used in the analysis. From the analysis of all test materials, a particular recycled plastic material is chosen, suggesting its potential suitability for use in automotive bumper production. Overall, this research offers significant insights into the development of radar-compatible recycled plastics for bumper design and manufacturing.
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Probing electronic nematicity and anisotropic electron-phonon coupling in strained YBCO nanowires
(2024) Rongrueangkul, Karn; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap (MC2); Chalmers University of Technology / Department of Microtechnology and Nanoscience (MC2); Lombardi, Floriana; Kalaboukhov, Alexei; Bauch, Thilo
Despite nearly 40 years since its discovery in 1986, the underlying mechanism behind the high-temperature superconductivity (HTS) in cuprates remains a significant enigma in condensed matter physics. The existence of multiple intertwined local orders, originating from the strongly correlated electrons, further complicates the study of these materials. Such complexity of the normal state is depicted in a very intricate temperature-doping phase diagram. A way to advance the knowledge of these materials is to tune the local orders, both in the superconducting and in the normal state, to disentangle them for individual study. One way to achieve such an effect is to apply strain to the cuprates in nm-thick films. Previously, it was discovered that the unidirectional strain, induced by few-unit-cell-thick films deposited on a nanostructured surface, can modify the charge order and cause the in-plane resistivity of the films to become much more anisotropic than in bulk materials. According to the Boltzmann transport model, such anisotropy in the in-plane resistivity is due to the directional modification of the Fermi velocity in which the velocity along one crystallographic in-plane direction is much higher than another. This results in an anisotropic Fermi surface that connects to the presence of an electronic nematicity, wherein the electronic structure retains translational symmetry while spontaneously breaking rotational symmetry. In earlier reports on the archetypal HTS YBa2Cu3O7−δ (YBCO) superconductor, the photoemission and transport measurements appear to show that electron-phonon coupling (EPC) can become directionally suppressed if the Fermi surface becomes nematic (as in our sample). This should strongly affect the heat transport in nm-thick YBCO films. Hence, the focus of this thesis work is to investigate the anisotropic EPC through the study of electrical and heat transport properties of YBCO nanowires oriented along different crystallographic axes. The nanowires are fabricated from YBCO thin films epitaxially grown by the Pulsed Laser Deposition technique, and the strain is tuned by modifying the film thickness.
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Aircraft simulations using hydrogen as an energy carrier
(2023) Hall, Jonathan; Mustafha, Mohamed; Shanbhag, Shashank Gobalkrishna; Chalmers tekniska högskola; Chalmers University of Technolog; Wickman, Björn; Grönstedt, Tomas
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Extra High Tensile Steel Applications for RoPax ferries
(2024) Ribeiro Da Silva Mangas Pereira, Ana Carolina; Chalmers tekniska högskola / Institutionen för mekanik och maritima vetenskaper; Chalmers University of Technology / Department of Mechanics and Maritime Sciences; Li, Zhiyuan; Li, Zhiyuan
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From Learning to Execution: A General Interface for Kinesthetic Teaching in Robotics
(2024) Ahlebrand, Hampus; Chalmers tekniska högskola / Institutionen för elektroteknik; Dean, Emmanuel; Ramirez, Karinne