École Polytechnique Fédérale de Lausanne
Infoscience - École polytechnique fédérale de LausanneNot a member yet
191401 research outputs found
Sort by
WeChat as an unavoidable research tool for fieldwork, and its problems
No full textI did not use WeChat as my main method or main source of materials, but I realized that during my fieldwork in China, I did use WeChat very often to help me collect data, and I see the potential of using WeChat as an increasingly important method for further research in China. Since I did not dig deeper with WeChat data, this proposal is mainly served as a starting point to help me think about potential approaches about “WeChat ethnography” and I would be willing to join the discussion and learn from scholars about how they use WeChat as a method for their research projects. I would like to share some ideas of how WeChat were used during my fieldwork in Beijing and Zhangjiakou for my research project about the Beijing 2022 Winter Olympics. During my stay in Beijing in the first half year of 2022, I suffered from different forms of physical and digital restrictions, and therefore even I was on site, I did a number of interviews through WeChat, including video, voice, and text interviews, as well as informal chats, but I also encountered problems in terms of how to conduct effective virtual interviews, how to find useful informants, and how to communicate more deeply. Meanwhile, I also figured out differentforms of second-hand information collection approaches via WeChat, such as through WeChat official accounts and mini-programs, as well as private WeChat groups serving as an agency platform. I also relied on informal information shared through my local friends as I was blocked in Beijing and could not access my field during my stay. Lastly, there were of course some other functions of WeChat, such as payment that has been studied by many scholars, and in the Covid era, some important functions have been incorporated into WeChat, such as the health code system that is even used to detect people’s daily Covid test results, which I describe it as a new approach of digital regulation/surveillance. Thus, I follow Plantin & de Seta (2019)’s argument that WeChat is an infrastructure, which penetrates into people’s everyday life, and is unavoidable if we want to do research in/related to China.SCI-ENAC-FGBgrpc
Gerstenhaber structure on Hochschild cohomology of the Fomin–Kirillov algebra on 3 generators
No full textThe goal of this article is to compute the Gerstenhaber bracket of the Hochschild cohomology of the Fomin–Kirillov algebra on three generators over a field of characteristic different from 2 and 3. This is in part based on a general method we introduce to easily compute the Gerstenhaber bracket between elements of HH0(A) and elements of HHn(A) for n∈N0, the method by M. Suárez-Álvarez [J. Pure Appl. Algebra 221, No. 8, 1981–1998 (2017; Zbl 1392.16009)] to calculate the Gerstenhaber bracket between elements of HH1(A) and elements of HHn(A) for any n∈N0, as well as an elementary result that allows to compute the remaining brackets from the previous ones. We also show that the Gerstenhaber bracket of HH∙(A) is not induced by any Batalin–Vilkovisky generator.AVP-E-CAP
Military and Art Museum Bunkered into the Landscape
No full textThe project is situated at the entrance of the Sado Estuary, a crucial location for the defense of Lisbon and Setubal. This place witnessed military occupations at various historical periods. Faced with abandonment and destruction, the intervention focuses on the site of the Old Fort (17th c.) and 7th Artillery Battery (WWII), located on top of a cliff. The proposal is defined by a new structure that connects the military buildings (Old Fort, Entrenched Buildings, and 3 Batteries) guiding visitors to understand and discover the place in a unique way. This new structure integrates a museum that features a permanent exhibition on coastal defense and temporary installations of contemporary art. The museum represents the overlapping of three distinct periods: the Old Fort period, the 7th Battery period; and the Museum period. Preserving, adapting, and rebuilding are interconnected actions, that form the very foundation of the museum project itself. The museum appears as a new mark in time connecting and adapting the pre-existing structures. The visitors’ journey is defined by a series of diverse spaces where light guides them through underground areas, creating a sense of surprise and wonder. The proposal works with the topography, mainly through underground spaces, employing the same camouflage logic used in bunkers. The project blends into the landscape, remaining invisible from the outside, without keeping the protagonist away from pre-existing heritage structures and preserving the protected landscape.MANSLAB-COCDHSAR-DCote: 2023.014MEM.1/2 autre, MEM.2/2 autreGroupe de suivi: Blanc, Alexandre (dir. pédagogique) ; Graezer Bideau, Florence (prof.) ; Nay, Nicole (maître EPFL) ; Wellinger, Jeanne (expert)Professeur responsable de l'Enoncé: Graezer Bideau, Florence (EPFL CDH-DIR)Enoncé théorique de master: Defense of the coast: Outão
Scalable Logic Rewriting Using Don’t Cares
No full textLogic rewriting is a powerful optimization technique that replaces small sections of a Boolean network with better implementations. Typically, exact synthesis is used to compute optimum replacement on-the-fly, with possible support for Boolean don't cares. However, exact synthesis is computationally expensive, rendering it impractical in industrial tools. For this reason, optimum structures are typically pre-computed and stored in a database, commonly limited to 4-inputs. Nevertheless, this method does not support the use of don't cares. In this paper, we propose a technique to enable the usage of don't cares in pre-computed databases. We show how to process the database and perform Boolean matching with Boolean don't cares, with negligible run time overhead. Logic rewriting techniques are typically very effective at optimizing majority-inverter graphs (MIGs). In the experiments, we show that the usage of don't cares in logic rewriting on MIGs offers an average size improvement of 4.31% and up to 14.32% compared to state-of-the-art synthesis flow.LSI1LSI
Observation of muonic Dalitz decays of chib mesons and precise spectroscopy of hidden-beauty states
No full textThe decays of the χb1(1P), χb2(1P), χb1(2P) and χb2(2P) mesons into the Υ(1S)μ+μ− final state are observed with a high significance using proton-proton collision data collected with the LHCb detector and corresponding to an integrated luminosity of 9 fb−1. The newly observed decays together with the Υ(2S) → Υ(1S)π+π− and Υ(3S) → Υ(2S)π+π− decay modes are used for precision measurements of the mass and mass splittings for the hidden-beauty states.LPHE-OSPH-SBLPHE-RMLPHE-L
Deterministic grayscale nanotopography to engineer mobilities in strained MoS<inf>2</inf> FETs
No full textField-effect transistors (FETs) based on two-dimensional materials (2DMs) with atomically thin channels have emerged as a promising platform for beyond-silicon electronics. However, low carrier mobility in 2DM transistors driven by phonon scattering remains a critical challenge. To address this issue, we propose the controlled introduction of localized tensile strain as an effective means to inhibit electron-phonon scattering in 2DM. Strain is achieved by conformally adhering the 2DM via van der Waals forces to a dielectric layer previously nanoengineered with a gray-tone topography. Our results show that monolayer MoS2 FETs under tensile strain achieve an 8-fold increase in on-state current, reaching mobilities of 185 cm²/Vs at room temperature, in good agreement with theoretical calculations. The present work on nanotopographic grayscale surface engineering and the use of high-quality dielectric materials has the potential to find application in the nanofabrication of photonic and nanoelectronic devices.LMIS1PRNMARVEL-GELQPLBNITHEOSLANE
On the performance of learning-based image compression as source coding for JPEG DNA
No full textUsing DNA molecules for data storage presents a compelling solution to the ever-growing demand for efficient and sustainable data storage systems. DNA offers notable advantages in terms of storage density, longevity, and energy efficiency. This has made the development of effective coding and compression techniques for DNA-based storage a critical research area within signal processing. One particularly challenging aspect is the encoding of multimedia content, such as images, for storage in DNA. JPEG DNA, a recent standardization effort led by the JPEG Committee, addresses this challenge by integrating both source and channel coding. The source coding focuses on data compression, while the channel coding ensures error resilience and accommodates the biochemical constraints of the DNA medium. In this paper, the impact of integrating learning-based source coding into the JPEG DNA framework is explored. This study reveals promising improvements in performance by replacing traditional image compression techniques with a learning-based approach, highlighting the potential for further advancements in DNA-based data storage.GR-E
Demonstration of full polarization control of soft X-ray pulses with Apple X undulators at SwissFEL using recoil ion momentum spectroscopy
No full textThe ability to freely control the polarization of X-rays enables measurement techniques relying on circular or linear dichroism, which have become indispensable tools for characterizing the properties of chiral molecules or magnetic structures. Therefore, the demand for polarization control in X-ray free-electron lasers is increasing to enable polarization-sensitive dynamical studies on ultra-fast time scales. The soft X-ray branch Athos of SwissFEL was designed with the aim of providing freely adjustable and arbitrary polarization by building its undulator solely from modules of the novel Apple X type. In this paper, the magnetic model of the linear inclined and circular Apple X polarization schemes are studied. The polarization is characterized by measuring the angular electron emission distributions of helium for various polarizations using cold target recoil ion momentum spectroscopy. The generation of fully linear polarized light of arbitrary angle, as well as elliptical polarizations of varying degree, are demonstrated.LUX
Colonie arboricole Revalorisation et extension d’un village dans le Nord Vaudois
No full textLa ferme vaudoise s’inscrit dans le paysage de plaine comme un témoin des évolutions du système agricole. Architecture de résistance, elle s’est construite comme un système autonome permettant une autosuffisance alimentaire. Comme beaucoup de typologies rurales, la ferme vaudoise regroupe sous le même toit habitat et activité. Ceci amène à reconsidérer la vie villageoise, où les besoins essentiels de la vie quotidienne sont couverts par les ressources de proximité. Car les villages sont délaissés, voués au statut de cités dortoirs, il s’agit dès lors de proposer une alternative à une politique d’aménagement centralisée à partir de la typologie étudiée, tout en prenant en compte les enjeux environnementaux et la crise des ressources actuels. Le projet s’implante dans la continuité de la rue existante et se structure sous la forme d’un dispositif qui alterne le logement et l’activité, en reprenant les qualités de la typologie originelle telles que le couloir traversant et la maisonnette compacte. De plus, le verger faisant partie intégrante d’un tel ensemble, une plantation d’arbres fruitiers en cultures associées, inspirée des principes agroécologiques, est introduite et complétée par une activité de transformation liée à cette production. Ainsi, le projet se propose comme un système semi-autonome inscrit dans l’économie locale d’un village pouvant être complétée par d’autres unités d’exploitation. Le principe pourrait s’étendre dans une vision territoriale par la multiplication de centres ruraux dans une politique économique de circuit courtLAPISENAC-SARCote: 2024.024MEM.1/1Groupe de suivi: Braghieri, Nicola (dir. pédagogique) ; Fröhlich, Anja (prof.) ; Zurbruegg, Pierre (maître EPFL) ; Wéry, Jeanne (expert)Professeur responsable de l'Enoncé: Braghieri, Nicola (ENAC IA LAPIS)Enoncé théorique de master: La maison paysanne vaudoise: évolution et potentiel d’une typologie agricol