9,604 Works

Methodology for efficient use of thermal energy in the chemical and petrochemical industry

Elfie Marie Méchaussie
The current European energy regulation, aligned with the European Union energy strategy and targets for the next decade, requires large industrial companies to regularly assess their energy performance and implement energy efficiency improvement measures. In many cases, these energy reviews fulfill minimum criteria for energy audits set by the legislation, and focus on the optimisation of the energy conversion units and utilities distribution. Opportunities for energy savings within production processes are missed, which can also...

Three methodological contributions towards modelling endogenous policy-emergence in societal transitions

Reinier Verhoog
Today we are facing many politically driven sustainability transitions in complex sociotechnical systems. Sustainability transition scholars look at these transitions with their own theoretical lenses, often paying too little attention to the interactions of power, politics and agency. While simulation is a useful method to address the complexity of long-term sustainability transitions, the number of transition studies using simulation is limited, as the field is still dominated by the use of qualitative case studies. This...

Defect chemistry of methylammonium lead iodide

Alessandro Senocrate
The present work deals with the defect chemistry and charge transport properties in halide perovskites, and in particular in the archetypal methylammonium lead iodide. These materials are extensively researched due to their very promising application as light-harvesters in solar cells and in other optoelectronic devices. Notwithstanding the numerous studies dealing with these materials (especially with their optical and electronic properties, and with device application), a significant portion of the underlying physics and chemistry is still...

IT Investment and its impacts:does IT matter during crisis, during financing and in Innovation?

Shameem Hasan
This thesis empirically explored the impacts of IT investment on three different scenarios under the common denominator / threads of IT investments. It comprises three different essays on the impacts of IT investments. IT investments and its impact on many aspects of the firms are well known - like performance / productivity, output, market value etc. But I looked into areas that were not explored before and examined events that didnât take place after the...

Aerial Human-Comfortable Collision-free Navigation in Dense Environments

Nicolas Dousse
With current overuse of the road transportation system and planned increase in traffic, inno- vative solutions that overcome environmental and financial cost of the current system should be assessed. A promising idea is the use of the third dimension for personal transportation. Therefore, the European project myCopter, funded under the 7th framework, aimed at en- abling the technologies for Personal Aerial Transportation Systems as breakthrough in 21st century transportation systems. This project was the starting...

Fréchet means in Wasserstein space:theory and algorithms

Yoav Zemel
This work studies the problem of statistical inference for Fréchet means in the Wasserstein space of measures on Euclidean spaces, $\mathcal W_2 ( \mathbb R^d )$. This question arises naturally from the problem of separating amplitude and phase variation in point processes, analogous to a well-known problem in functional data analysis. We formulate the point process version of the problem, show that it is canonically equivalent to that of estimating Fréchet means in $\mathcal W_2...

Control of Topological Magnetic Textures by Magnetic and Electric Fields in Magnetoelectric Helimagnet Cu₂OSeO₃

Ping Huang
Magnetic skyrmions, topologically non-trivial chiral whirl-like spin configurations, have been under massive investigations in both fundamental and application aspects. In some special compounds, these quasi-particles can formtriangular skrymion lattice (SkL) exhibiting abundant unique properties. This thesis presents my comprehensive studies on the SkL in the magnetoelectric (ME) coupling helimagnet Cu2OSeO3. Starting from measurements on single crystal bulk Cu2OSeO3 samples, including dc magnetization, magnetoelectric susceptibility and neutron scattering, so as to get the general understanding of...

Charge Carrier Dynamics in Organo Lead Halide Perovskites

Mahmoud Saeed Qaid Mohammad Hezam
In the last five years, organo lead halide perovskites have emerged as a new and efficient player in the field of photovoltaics, jumping in a short time to an advanced front position. This class of materials has also shown proficient light emission capabilities, and perovskite-based light emission devices have been demonstrated as well. Therefore, the optical characterization of these materials has been widely used to explain and evaluate their light absorption/emission characteristics. Despite their remarkable...

Tailoring Surface Properties of Fiber Materials:Novel Opportunities in the Fabrication of Multi-scale Fiber-based Architectures

Dang Tung Nguyen
Many surface properties of materials can be tailored by a proper physical patterning. Such patterned surfaces, commonly fabricated by wafer-based techniques, have been widely exploited for light trapping in advanced photovoltaic systems, for tailoring the hydrophobicity of surface, and for enabling the preferential positioning and growth of biological cells. Nevertheless, wafer-based techniques, despite being versatile and mature, are limited to small, flat and rigid Silicon substrates. There is however an increasing demand for micro and...

Defects on surface and interface for photoelectrochemical properties of hematite photoanodes

Yelin Hu
Hydrogen is a highly versatile fuel that may become one of the key solutions to face our future energy challenges. Among all these methods for hydrogen production, solar water splitting offers possible advantages regarding components integration, stability and costs. The key component for photoelectrochemical (PEC) water splitting is the semiconductor photoelectrode, which requires many material requirements in a single component, such as light absorption, charge separation, charge transport, H2 or O2 evolution kinetics at surface...

Brevets de la maison en béton, 1892-1923:visions d'une construction monolithique, d'Edison à Le Corbusier

Gia Bao Khue Aurélie Do-Tran
Looking back at the history of concrete houses around 1900, we can discover how reinforced concrete, initially tied to construction systems of renowned inventors (and other less known), is gradually becoming autonomous and a material on its own, highlighted for its aesthetics and malleability. Also, studying the different experiments by businesses, designers, developers, engineers or architects and linked to the interpretation of the structure, yields novel ideas. The research process focuses on construction technic in...

Rake, Peel, Sketch:The Signal Processing Pipeline Revisited

Robin Scheibler
The prototypical signal processing pipeline can be divided into four blocks. Representation of the signal in a basis suitable for processing. Enhancement of the meaningful part of the signal and noise reduction. Estimation of important statistical properties of the signal. Adaptive processing to track and adapt to changes in the signal statistics. This thesis revisits each of these blocks and proposes new algorithms, borrowing ideas from information theory, theoretical computer science, or communications. First, we...

Optimal Representations of Sparse Stochastic Processes with Applications in Image Processing

Pedram Pad
We establish in the world of stochastic processes a theoretical relation between sparsity and wavelets. The underlying principle is to treat stochastic processes as generalized functions, which facilitates the study of their properties in a transform domain. We focus on symmetric-$\alpha$-stable (S$\alpha$S) processes, with $\alpha\in(0,2]$. They are central to a recently proposed framework for sparse stochastic processes. The case $0

Aesthetic Space:The Visible and the Invisible in Urban Agency

Mirza Tursić
Recent 'turns' in social sciences, namely the visual, qualitative, actorial or spatial turns, all indicate a rising interest in individuals. Since the aesthetic dimension always nourishes and informs individualsâ spatialities and their decision-making processes, my research explores how the subjective realm of the aesthetic has proved itself able to generate conditions that lead to action, and consequently influence other dimensions of society, especially in the ethical, political or legal realms. My systemic approach is grounded...

Influence of structural and electrostatic disorder on transport properties of monolayers of two-dimensional semiconductors

Dmitry Ovchinnikov
Two-dimensional (2D) materials are under intensive investigation recently due to variety of electronic properties, ranging from insulators (h-BN) to semi-metals (graphene), semiconductors (MoS2, WSe2) with wide variability of band-gap and correlated phases (NbSe2, TaS2). Recently, focus of research has been moved from graphene, which is now a well understood material, towards less explored materials, in particular monolayers of semiconducting transition metal dichalcogenides (TMDCs) such as MoS2 with direct band-gap in optical range (1.5 - 2...

Limitations of Proximity Lithography Printing:Simulations, Experiments, and Applications

Krishnaparvathy Puthankovilakam
Photolithography is one of the earliest technologies used to transfer patterns to a substrate. It is also known as optical lithography since it uses light to transfer the pattern. The main exposure techniques exist in the industry are projection printing, contact printing, and proximity printing. Projection printing technology uses optical elements between mask and wafer to project the feature on the mask to the wafer. This is very expensive and delivers the highest resolution. In...

Advanced Plasmonic Nanostructures for Engineering Fluorescence Applications

Xiaolong Wang
The appeal of plasmonics lies in the unique properties of coinage metal nanoparticles to strongly confine and enhance electromagnetic fields at the subwavelength. A simple 50 nm colloidal plasmonic particle can not only break the classical diffraction limit and produce subwavelength imaging, but it can also absorb light for killing cancer cells. A dipole gap antenna or a nanohole in a thin filmcan concentrate light below 10 nm, thus opening many perspectives, such as highly...

Rack-Scale Memory Pooling for Datacenters

Stanko Novakovic
The rise of web-scale services has led to a staggering growth in user data on the Internet. To transform such a vast raw data into valuable information for the user and provide quality assurances, it is important to minimize access latency and enable in-memory processing. For more than a decade, the only practical way to accommodate for ever-growing data in memory has been to scale out server resources, which has led to the emergence of...

Functional and Adaptive Construction for Rescue:an Analysis of the Approach Using Autonomous Robots

Hadi Ardiny
Although recent advances in the field of robotics have greatly increased robotic capabilities for several applications, autonomous robots are still in their infancy regarding their support of onsite construction. Unlike production robots that are used, for instance, in automotive industries, autonomous robotic systems should be designed with special considerations, such as the complexity of the cluttered and dynamic working space, inaccuracy in positioning because of the nature of mobile systems, and so forth. Thus, construction...

Power-System State Estimation based on PMUs:Static and Dynamic Approaches - from Theory to Real Implementation

Lorenzo Zanni
An increasing number of phasor measurement units (PMUs) are being deployed in power systems in order to enhance the situational awareness and, in the near future, we expect that many networks will be extensively equipped with PMUs. These devices provide accurate and synchronized voltage/current phasors (called synchrophasors) at a reporting rate up to 60 measurements-per-second, which is a significantly different type of information with respect to the commonly-used voltage/current magnitude and power measurements of remote...

Hydrodynamics of Francis turbine operation at deep part load condition

Keita Yamamoto
The electrical energy production from New and Renewable Energy (NRE) sources have become increasingly important in the past decades. However, intermittent electrical generation from NRE sources due to their stochastic nature often prevents stable power output from existing power grids. To enable a smooth integration of NRE sources, flexible operations at hydraulic power plants are key to providing the capability of primary and secondary grid control to balance the energy production. The rapid growth of...

Antennas for low-cost Ka-band ground terminal devices

Joana Rita Alves Dos Santos Silva
The ever-growing demand for high-speed data links together with the increasing congestion in the traditional microwave spectrum are pushing for the exploitation of higher microwave and millimeter-wave (mm-wave) frequencies, including the so-called Ka band. Major investments came along, especially in the satellite communications industry, raising the technological con-straints imposed on electronic equipment, mainly concerning performance, compactness and both reduced cost and weight. The great antenna size reduction achieved at Ka band has boosted the research...

Acoustic emission source detection and wave generation on a working plate using piezoelectric actuators

Xinchang Liu
In modern automated assembly lines, part feeders play an important role to separate and sort parts. Agility and flexibility are required to achieve a good yield for different types of parts. The common working principle is to vibrate a working plate driven by electromagnetic actuators in order to orient or separate parts on it. Then, a vision system will help a robotic arm to pick up the parts if they are correctly placed. However, the...

Properties of Enzymes Involved in Tetrachloroethene Respiration:From Physiology to Protein Function

Géraldine Florence Buttet
Tetrachloroethene (PCE) pollution threatens nature and human health due to its toxic and carcinogenic potential. Due to industrial activities, large amounts of PCE were discharged into the environment over the last decades and represent one of major groundwater pollutants. Organohalide respiration (OHR) is a bacterial anaerobic respiration in which the halogenated compounds, such as chloroethenes, are used as terminal electron acceptors. This process requires the presence of an electron transport chain located in the cytoplasmic...

Atomically Thin Two-dimensional Materials Grown by Molecular Beam Epitaxy

Ming-Wei Chen
Atomically thin two-dimensional (2D) materials have attracted great interest due to their unique optoelectronic properties which are very different from their bulk counterparts. Most of the proof-of-concept devices, however, have been demonstrated using the scotch tape exfoliation method. The low yield thus limits the application of 2D materials and prevents them from meeting industry criteria. In order to fulfill potential roadmaps, it is essential to develop a reliable growth route and investigate the fundamental properties...

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