9,211 Works

Impact and post-impact flexural behavior of composite sandwich structures in extreme low temperature arctic conditions

Kwek-Tze Tan & Khan, Md. Mahfujul

Fluctuation Analysis of Repetitive Writing Motion by Using DFA

Masafumi Uchida

MATHICSE Technical Report : Incremental computation of block triangular matrix exponentials with application to option pricing

Daniel Kressner, Robert Luce & Francesco Statti
We study the problem of computing the matrix exponential of a block triangular matrix in a peculiar way: Block column by block column, from left to right. The need for such an evaluation scheme arises naturally in the context of option pricing in polynomial diffusion models. In this setting a discretization process produces a sequence of nested block triangular matrices, and their exponentials are to be computed at each stage, until a dynamically evaluated criterion...

Non-equilibrium dynamics of di-platinum complexes and molecular dyes in solution: Insights from transient absorption and two-dimensional Fourier transform spectroscopy

Lars-Hendrik Mewes
Unraveling the interplay between electronic- and vibrational degrees of freedom on the earliest time scales of physical, chemical and biological processes is crucial to gaining insight into the mechanisms that govern the world around us, since it is during these primary steps that the fate of the excitation energy - be it solar, chemical or physical - is decided. A tiny structural change during the first 10s of femtoseconds can for example predetermine the dynamics...

Modeling the kinetics of the main peak and later age of alite hydration

Alexandre Reda Constantin William Caleb Ouzia
The aim of this thesis is to understand the mechanisms underlying the main hydration peak and later ages of alite hydration; it proposes new mechanistic models for these two stages. Alite is the main constituent of Portland Cement (PC), and is responsible for the setting and hardening of concrete during the first reaction day. Because future cements will still be based on PC, alite remains worthy of investigation. Alite hydration can be divided into five...

Defecation initiates a stereotyped behavior in the cricket Gryllus bimaculatus

Keisuke Naniwa, Yasuhiro Sugimoto, Koichi Osuka & Hitoshi Aonuma

Ascorbate Detection Using Single-Trap Phenomena in Two-Layer Si NW FETs

Yurii Kutovyi, Ihor Zadorozhnyi, Natalia Naumova, Nazarii Boichuk & Mykhaylo Petrychuk

Targeting mitochondrial bioenergetics and NAD+ metabolism during sarcopenia and regeneration of skeletal muscle

Tanja Sonntag
The progressive decline of muscle mass and function called sarcopenia is a multi-factorial process associated to frailty, disability, and low quality of life in the elderly. The co-factor nicotinamide adenine dinucleotide (NAD+) becomes a limiting factor in the course of aging and other pathological conditions. It has emerged as a major regulator of cellular metabolism, which is modulated by dietary precursors of the vitamin B3 family. So far, no direct link between sarcopenia and alterations...

A novel microfabrication platform for hybrid multilayer MEMS

Nahid Hosseini
In Atomic force microscopy (AFM), the tip-sample interaction force can be measured through two primary detection techniques: optical beam detection (OBD) and electrical (self-sensing) readout. Compared to the optical method, the convenience of the self-sensing readout AFM measurements comes at the cost of higher force noise. In the self-sensing method, there is a trade-off between reducing the force noise and maintaining the cantilever characteristics (e.g. resonance frequency, spring constant, quality factor, and planar dimension) within...

Sandwich structures with synthetic and natural fiber composite skins under flexural and axial loading

Amir Fam

MATHICSE Technical Report : Preconditioned low-rank Riemannian optimization for linear systems with tensor product structure

Daniel Kressner, Michael Maximilian Steinlechner & Bart Carl Vandereycken
The numerical solution of partial differential equations on high-dimensional domains gives rise to computationally challenging linear systems. When using standard discretization techniques, the size of the linear system grows exponentially with the number of dimensions, making the use of classic iterative solvers infeasible. During the last few years, low-rank tensor approaches have been developed that allow to mitigate this curse of dimensionality by exploiting the underlying structure of the linear operator. In this work, we...

Distributed State Estimation and Control of Autonomous Quadrotor Formations Using Exclusively Onboard Resources

Duarte Da Cruz Baptista Dias
The navigation of unmanned aerial vehicles operating in environments without global positioning systems, including global navigation satellite systems and motion capture systems, is a recent research topic, without much work reported in the literature. In indoor applications, particularly, small-scale vehicles are subjected to severe power and weight constraints, limiting their overall navigation capabilities. In such scenarios, multi-vehicle systems can be used in order to mitigate the impact of limited capabilities at the individual vehicle level....

Spin-Dependent Processes at Electrodes Detected by Simultaneously Performed EPR, Electrochemistry and EDMR

Felix Blumenschein
The electrically detected magnetic resonance (EDMR) results presented in this thesis demonstrate a spin dependence of the charge transfer between an electrode and an electrolyte. These results were found using simultaneous detection of continuous wave electron paramagnetic resonance (CW EPR), EDMR and cyclic voltammetry. The electrochemical cell was located inside a microwave cavity and the electrolyte was saturated withmethyl viologen radicals. Electrodes were either spin polarized using optical spin-pumping in p-GaAs or electrodes functionalized with...

Response of noise-amplifier flows: From linear control to nonlinear jet breakup

Isha Shukla
Among hydrodynamically unstable flows, the amplifier-flows are characterized by their large amplification potential in presence of external noise. Since amplifiers do not have an intrinsic dynamics, a chosen forcing can be applied to eventually control the downstream evolution of such flows. With this aim, we intend to analyse the flow control in amplifier-flows, common examples being the flow in a backward facing step and the free surface capillary jet. We begin by analysing the flow...

Secure, Confidential Blockchains Providing High Throughput and Low Latency

Eleftherios Kokoris Kogias
One of the core promises of blockchain technology is that of enabling trustworthy data dissemination in a trustless environment. What current blockchain systems deliver, however, is slow dissemination of public data, rendering blockchain technology unusable in settings where latency, transaction capacity, or data confidentiality are important. In this thesis we focus on providing solutions on two of the most pressing problems blockchain technology currently faces: scalability and data confidentiality. To address the scalability issue, we...

Multiscale experimental characterisation and modelling of transverse cracking in thin-ply composites

Sébastien Kohler
In this work, the damage dependency on ply thickness is investigated experimentally for three different thin-ply CFRP quasi-isotropic laminates, with constituents spanning a large range of properties. It is shown that free edge damage mechanisms, observed with in-situ microscopy, change with decreasing ply thickness. Whilst free-edge delamination dominates the damage behaviour when thicker plies are used, transverse cracking (TC) dominates the free edge behaviour of thinner plies with an increasing onset of damage with decreasing...

MATHICSE Technical Report : Perturbation analysis for the Darcy problem with log-normal permeability

Francesca Bonizzoni & Fabio Nobile
We study the single-phase flow in a saturated, bounded heterogeneous porous medium. We model the permeability as a log-normal random field. We perform a perturbation analysis, expanding the solution in Taylor series. The series is directly computable in the case of a random field parametrized by a finite number of random variables. On the other hand, in the case of an infinite dimensional random field, suitable equations satisfied by the derivatives of the stochastic solution...

Development of functionalized alginate-based hydrogels to reduce fibrosis in the transplantation of microencapsulated cells

François Rémi Pierre Noverraz
Nowadays, the development of cell therapy relies mainly on the advances made toward cell microencapsulation which allows to evade the need for immunosuppression during cell transplantation. Among the materials considered for cell encapsulation, hydrogels distinguish themselves by their exceptional properties. Due to its gelling properties in contact with divalent cations, the biopolymer sodium alginate (Na-alg), has been widely studied for the microencapsulation and transplantation of cells. However, several defects notably in permselectivity and durability in...

Scaling as a key conceptual tool for the interpretation of empirical and experimental patterns in ecology and biology

Silvia Zaoli
This thesis is concerned with regular patterns found in ecology and biology, their linkages and the statistical description of their fluctuations around average trends. Among such patterns, often conforming to power laws, well-known examples include the Species-Area relationship (SAR), quantifying the increase of the number of species S inhabiting an ecosystem with ecosystem area, and the scale-invariant body size spectrum, routinely observed, e.g., in aquatic ecosystems. In biology, Kleiber's law is an allometric relationship describing...

Tokamak plasma edge studies by microwave short-pulse reflectometry and backscattering

Pedro Andres Molina Cabrera
Moving towards an increased understanding of the dynamic processes in the edge of tokamak plasmas requires continuous innovation in diagnostic capabilities, pushing the envelope in both spatial and temporal dimenstions. Plasma density and rotation, and their respective fluctuations, are essential quantities for tokamak physics studies. The present thesis describes the design, development, and first results of two new dedicated diagnostics in the TCV tokamak of the reflectometry type: a heterodyne continuous- wave Doppler backscattering (DBS)...

Promoted Propulsion by Foot Windlass Mechanism in Jumping

Xiangxiao Liu, Tsung-Yuan Chen, Yuntong Xu, Shuhei Ikemoto, Masahiro Shimizu & Koh Hosoda

Structural design and optimization of FRP curved sandwich panels used as the enclosure structure of a large bridge

Xinmiao Meng & Peng Feng

Making large art historical photo archives searchable

Benoît Laurent Auguste Seguin
In recent years, museums, archives and other cultural institutions have initiated important programs to digitize their collections. Millions of artefacts (paintings, engravings, drawings, ancient photographs) are now represented in digital photographic format. Furthermore, through progress in standardization, a growing portion of these images are now available online, in an easily accessible manner. This thesis studies how such large-scale art history collection can be made searchable using new deep learning approaches for processing and comparing images....

SUBDIVIDE AND CONQUER Active Contours and Surfaces for Biomedical Image Segmentation

Anaïs Laure Marie-Thérèse Badoual
Ongoing advances in imaging techniques create new demands regarding the analysis of images in medicine and biology. Image segmentation is a key step of many image analysis pipelines and its proper execution is a particularly challenging task. This thesis is dedicated to the development of segmentation algorithms for biomedical structures in 2D and 3D images. In this work, we aim to improve upon classical parametric active contours/surfaces, whose limitations we address. This thesis is organized...

Wearable Technologies for Embodied Human-Robot Interaction

Carine Rognon
Robotic teleoperation is fundamental to augment the resilience, precision, and force of robots with the cognition of the operator. However, current interfaces, such as joysticks and remote controllers, are often complicated to handle since they require cognitive effort and learned skills. Wearable interfaces can enable more natural and intuitive interactions with robots, which would make robotic teleoperation accessible to a larger population of users for demanding tasks, such as manipulation or search-and-rescue. The aim of...

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