Publications

Flip-chip assembly of photonic components can be achieved at room temperature by using 10 μm pitch interconnects made of metallised oxide microtubes inserted into ductile reception pads. In order to reduce the electrical resistance of interconnects and the assembly force required, interconnect design in regard to geometry and materials used are optimised through electrical and mechanical finite elements (FEM) simulations. To reduce electrical resistance, one may increase the metallisation thickness or microtube inner diameter. To minimise the assembly force, reducing the reception pad diameter is recommended. Experiments on silicon (Si) test vehicles are conducted to validate these predictions; they indicate that there is no short circuit, with an effectiveness of 100 %. This is achieved first through the assembly of Al-0.5 %wCu metallised oxide microtubes into Al-0.5 %wCu reception pads, using a force less than 10 mN/interconnect and proved to have a resistance of 230 mΩ. Second, with gold (Au) metallised oxide microtubes in indium (In) pads assembled with a force less than 0.7 mN/ interconnect. Last interconnects have a resistance of 670 mΩ/interconnect and can still be reduced to 500 mΩ by 2 h annealing at 100 ◦C.

This study presents the first life cycle assessment for the municipal solid waste management system of Samsun, the largest city in the Black Sea region in Turkey (about 1 million people). Its importance is that it proposes to identify the environmental impacts and improvements for the waste management system planned to be implemented by 2023 and the separate collection at source system to be adopted in the future, within the scope of the zero waste policy. Six scenarios were compared using LCA to highlight the potential impacts from transportation. Data were collected from Samsun landfill, Ecoinvent 3 database, regional data collected with the industrial partner and literatures from scientific articles. Life cycle impact analysis was evaluated with the environmental footprint (EF) 3.0 method. In this study, it is reported that environmental impacts are sensitive to transport emissions and the recycling rate of virgin materials. According to the results, the Scenario S3 without the material recovery facility system was approved as the worst final disposal alternative. In contrast, the Scenario S5, which supports the separation of recyclable and organic wastes at the source, showed the most environmentally friendly performance. This research contributes to improving Samsun’s current municipal solid waste management (MSWM) system and policies for sustainable development.

This research aims to develop an acoustic design methodology for CLT floor assemblies using artificial neural networks approach by integration of life cycle assessment (LCA). 72 Lab-based measurements are used to develop the acoustic prediction tool. They are related to 29 different CLT-based floor assemblies. The weighted sound reduction index (Rw), and the weighted normalized impact sound pressure level (Ln,w) are estimated with an accuracy of 2 dB. Then a LCA study is conducted on wooden assemblies. The acoustic performance and their environmental impacts are compared to highlight trends that may guide decision-makers in the design phase. This paper initially found that CLT-based floor assemblies generally increase the environmental impacts to achieve better acoustic insulation. However, a good sound attenuation can be reached by selecting suitable acoustic solutions.

This study examines the influence of fiber orientation variability on the mechanical properties of wood, focusing on veneer clear wood specimens. The research is motivated by the need to develop high performance composite materials for sustainable transportation applications, particularly in reducing greenhouse gas emissions. The experimental protocol involves manufacturing veneers from beech wood, followed by producing the manufacturing of veneers from beech wood, followed by the production of small specimens with deliberate variations in fiber orientation. Non-destructive measurements of local fiber orientations and global density are conducted, along with tensile tests to determine local mechanical properties, i.e., Young's modulus, strength, and the shear modulus Advanced imaging techniques (DIC) and models for isotropic materials are employed for analysis.The resultsreveal that fiber orientation has a significant role in wood variability, with pronounced effects on Young's modulus and strength at low angles. Transversal and shear modulus appear lower than in the literature due to the cracks due to the manufacturing of veneer (peeling process).

Local authorities have a strategic role in mitigating the environmental impacts of the transport sector. However, they struggle to integrate environmental issues into their decision-making processes, especially planning. In the European context of the Sustainable Urban Mobility Plan approach and Strategic Environmental Assessments (SEAs), this paper scrutinises three French localities to determine the current best practices and limitations for designing mobility plans and integrating environmental issues. Several limitations are identified: (1) limited expertise in defining and characterising actions and objectives, which complexifies plans' design, understanding, and monitoring; (2) a lack of a framework to conduct long-term quantitative environmental assessments and to use the results to influence decision effectively; and (3) monitoring processes are barely described in the documents, and the planning horizon where objectives are defined is not in sync with the indicators’ mandatory evaluation period. This French case study thus reveals that European planning practices must be further analysed and improved to deal with the rising environmental concerns, e.g. through an operational framework to design mobility plans with effective integration of environmental issues.

Time synchronization is an important building block for deterministic low-power wireless networks such as IETF 6TiSCH. The synchronized nature of this class of networks can be used by the application running on it, including to start/stop actions in a coordinated fashion across different nodes. This is called “orchestration” in 6TiSCH parlance. This demo proposes to interpret this term literally, by turning each lowpower wireless device into an embedded musician. The network of 20 of these wireless musicians deployed across the demo space becomes an embedded orchestra, which plays John Williams’ iconic orchestral arrangement of the Star Wars anthem.

This work focuses on the 316L austenitic stainless-steel case-hardening microstructure, after the SPS process near the solid/liquid state transition temperature. This process, faster than conventional carburizing techniques, is equivalent to weld cladding, allowing the achievement of high surface carbon contents with large-size carbide grains in the case of partial melting. Three distinct zones were formed: internal carburizing, carburizing with melting, and carburizing with melting and chromium depletion; all three composed of mixed carbides (Cr0.4Fe0.6)7C3 distributed in an austenitic matrix. The internal carburizing layer growths following a parabolic kinetic law with kp 1027 cm2/s, while the advancement of the melting front is very fast and follows a linear law with kl = 1.0 3 1024 cm2/s at 1100 °C. The Cr-depleted fusion zone microstructure is similar to a composite material with a metallic matrix, which includes graphite particles, Mo-rich intermetallic phases, and core-shell eutectic carbides. The partial melting zone without Cr depletion shows the formation of a dense carbide layer with diameters exceeding 10 µm, constituting 60% of the volume, and achieving a hardness of 850 HV5. Its wear rate is about 100 times lower than the 316L steel, indicating a significant improvement in the alloy's wear behavior.

The purpose of this study is to explore the individual and combined effects of auditory and visual stimuli on stress perception within Virtual Reality (VR). The exploration utilized physiological measures as Blood Volume Pulse (BVP), psychological assessments like the State-Trait Anxiety Inventory-Short Form (STAI-S), and NASA Task Load Index (NASA-TLX). Participants were immersed in two contrasting VR environments. The first environment was a tranquil forest, whereas the second scene was a chaotic city. Participants’ stress levels under different sensory conditions were assessed methodically by switching between congruent and incongruent audio-visual experiences. The findings of this study contribute to our understanding of sensory impacts on stress perception in VR environments and to the development of individualized VR experiences specific to individuals’ sensory preferences. While the findings suggest some individual variability in stress responses, particularly in audio versus visual stimulus dominance, these observations were not statistically significant, indicating a need for further exploration into personalized sensory experiences in VR.

This study proposes a model for the influence of work hardening and microstructure on the thermal relaxation of residual stresses. To construct such a model, an experimental campaign is first conducted on shot peened samples of Inconel 718 to generate different levels of residual stress and work hardening. The effect of the grain size and the size of the strengthening precipitates is investigated by producing two modified microstructures. Two shot peening conditions are used to introduce several profiles of residual stress and work hardening. These profiles are evaluated using X-ray diffraction. A thermal loading is then applied at 550°C with varying holding times, leading to a rapid but not complete relaxation of the residual stresses and work hardening. The experimental results exhibit the fact that the work hardening levels have a significant influence on this relaxation while the grain size and the size of the strengthening precipitates have a very moderate influence. Based on these experimental results, a model is proposed that considers the influence of work hardening on the thermal relaxation of residual stresses with some predictive applications. It is therefore possible to estimate the relaxation of residual stresses at any point on a shot peened part.

In the context of cochlear implants, which are now widely used, and innovative active devices, the cranial implantation of electronic devices raises new questions about the mechanical interactions between the implant and the skull. The aim of this study was to build a methodology using experimental data and numerical simulations to evaluate the mechanical interactions between the skull and the WIMAGINE® active cranial implant intended for use for tetraplegic patients. A finite element model of the implant housing and a simplified model of the three-layered skull were developed. 2.5 J-hammer impact tests were performed on implant housings and ovine cadaver heads for model calibration. The two models were then combined to analyze the interactions between the skull and the implant and compared against impact tests. The implant dissipates a certain amount of the impact energy which could be a parameter to include in implant design in addition to the implant integrity, tending to increase the implant stiffness. The non-implanted as well as the implanted lamb heads demonstrated an overall good resistance to the impact tests. The models correlated well with the experimental data, and improvements of the model through more realistic geometry (CT-scans) and more complex material behavior could now be implemented. Such a model could then be used with human head geometries and help for future implant design optimizations using numerical models of the implant-skull and even implant-head complex.