ETH Zurich Research Articles

Lacaton & Vassal: Open Conditions for Permanent Change. Interview with Anne Lacaton


 
 
 
 Interview by Jose? Mayoral MoratillaRealized in Lacaton & Vassal Architects Office, Paris (December 21st, 2018).
 
 
 
 
 Anne Lacaton, founding partner of Lacaton & Vassal, is a professor at ETH Zurich and has been a visiting professor at ETSAM, EPFL, TU Delft and Harvard University, among other institutions. The work of Lacaton & Vassal has been widely published, including monographs in 2G and El Croquis, and has been recognized with the granting of the EU Mies Award in 2019.
 From their first house, Maison Latapie, to the transformation of 530 dwellings in Bordeaux, Lacaton and Vassal’s approach aims to create open conditions to facilitate permanent change. Expanding the space, doubling the height, and increasing the structural capacity are several of the spatial strategies they employ to embrace evolution and change.

Sensitivity analysis on the impact of geometrical and operational variations on turbine hub cavity modes and practical methods to control them

This paper presents an experimental investigation on the impact of different design and operational variations on the instabilities induced at the hub cavity outlet of a turbine. The experiments were conducted at the “LISA” test facility at ETH Zurich. The axial gap at the 2nd stage hub cavity exit was varied, and also three different flow deflectors were implemented at the cavity exit to control the cavity modes (CMs). Furthermore, the turbine pressure ratio was altered to mimic the off-design condition and study the sensitivity of the CMs to this parameter. Measurements were performed using pneumatic, and Fast Response Aerodynamic Probes (FRAP) at stator and rotor exit. In addition, unsteady pressure transducers were installed at the cavity exit wall to measure the characteristic parameters of the CMs. For the small axial gap, distinct and strong CMs were generated, which actively interacted with stator and rotor hub flow structures. Increasing the gap damped the fluctuations; however, a broader range of frequencies was amplified. The flow deflectors successfully suppressed the CMs by manipulating the shear layer velocity profile and blocking the growing instabilities. Eventually, the increase in the turbine pressure ratio strengthened the CMs and vice versa.

Clariant signs catalysis research partnership with prestigious ETH Zurich University

Clariant signs catalysis research partnership with prestigious ETH Zurich University

Shaking table investigation of inelastic deformation demand for a structure isolated using friction-pendulum sliding bearings

This study aims at investigating experimentally if seismically isolated structures can manifest inelastic behavior when they are subjected to strong earthquake ground motion excitation. A steel structure is seismically isolated with four friction pendulum bearings and subjected to an ensemble of recorded earthquake ground motion excitations using the shaking table of ETH Zurich Laboratory. The structure is designed to concentrate its inelastic behavior on a mechanical clevis connection comprising two hinges and a pair of replaceable steel coupons. The use of this configuration enables the adjustment of the strength of the structure and thus the parametric investigation of its displacement ductility demand µ for a wide range of earthquake ground motion excitations. The experimentally derived values of the ductility demand µ for the seismically isolated structure are compared with the analytically determined values obtained through the use of Ry-μ-Tn relations for fixed-based structures and the corresponding relations developed for seismically isolated structures.

Turbine Hub Cavity Modes and Their Impact on Efficiency

Abstract Non-synchronous pressure and temperature fluctuations at the hub cavity of a turbine stage are the main focus of this study. Cavity modes are unsteady fluctuations generated at the cavity exit due to instabilities in this region. The cavity modes carried into the main flow impose an unsteady flow field in the rotor passages, which varies the passage-wise flow parameters considerably. A two-stage axial turbine was designed and tested in the “LISA” test facility at ETH Zurich. A reference case with baseline geometry and a modified case with an axial deflector at the hub cavity exit were tested. Comprehensive unsteady pressure and temperature measurements were performed using fast response aerodynamic (FRAP) and entropy probes (FENT), respectively. In addition, 12 fast response unsteady pressure transducers were mounted on the stationary wall of the cavity exit to measure the main characteristic parameters of the cavity modes. Full annular unsteady simulations were also carried out for both cases to support the experiments. Computational fluid dynamics (CFD) successfully predicted the effect of cavity modes on both frequency and amplitude of the fluctuations. The cavity modes indicated fluctuation amplitudes up to eight times of the blade passing fluctuations at the cavity exit. The analysis shows that the convected cavity modes alter the efficiency of different rotor passages by redistributing the mass flow and the losses resulting in a drop in overall efficiency. This work suggests that implementing a small axial deflector at the hub cavity exit would completely eliminate the cavity modes leading to a reduced pressure unsteadiness and enhanced efficiency.

Evaluation of the Chemistry Knowledge of Students Entering the ETH Zurich with a Moodle Quiz.

The basic chemistry knowledge of first-year students in the disciplines Chemistry, Biology, Pharmaceutical Sciences, and Health Sciences and Technology has been evaluated within the first three weeks of the Fall semester with a Moodle-based quiz at ETH Zurich. It consists of 37 small problems testing the knowledge that ETH students entering the lecture courses General Chemistry 1 (Inorganic Chemistry) (AC1) and Organic Chemistry 1 (OC1) should ideally have. An initial set of questions was developed by Bernhard Jaun (ETH Zurich) in 2007, it was combined with questions from an evaluation created in 2015 by Markus Müller (secondary school II teacher). The results of a total of 925 students who took part in the 2016 and 2017 evaluations are presented. It was found that 80% of the students of Chemistry, Chemical Engineering and Interdisciplinary Natural Sciences (AC1 course) and 70% of the students of Biology, Pharmaceutical Sciences, and Health Sciences and Technology (OC1 course) scored ≥60%. Students who took the focus course (Schwerpunktfach) Biology and Chemistry at the SEK II level (Swiss school system) performed on average 13-18% better and with a smaller standard deviation than other students. No significant differences were observed with regard to gender or the region in which the qualification for university entrance was obtained.

Full optical SESAM characterization methods in the 1.9 to 3-µm wavelength regime.

Semiconductor saturable absorber mirrors (SESAMs) are widely used for modelocking of various ultrafast lasers. The growing interest for SESAM-modelocked lasers in the short-wave infrared and mid-infrared regime requires precise characterization of SESAM parameters. Here, we present two SESAM characterization setups for a wavelength range of 1.9 to 3 µm to precisely measure both nonlinear reflectivity and time-resolved recovery dynamics. For the nonlinear reflectivity measurement, a high accuracy (<0.04%) over a wide fluence range (0.1-1500 µJ/cm2) is achieved. Time-resolved pump-probe measurements have a resolution of about 100 fs and a scan range of up to 680 ps. Using the two setups, we have fully characterized three different GaSb-SESAMs at an operation wavelength of 2.05 µm fabricated in the FIRST lab at ETH Zurich. The results show excellent performance suitable for modelocking diode-pumped solid-state and semiconductor disk lasers. We have measured saturation fluences of around 4µJ/cm2, modulation depths varying from 1% to 2.4%, low non-saturable losses (∼ 0.2%) and sufficiently fast recovery times (< 32 ps). The predicted influence of Auger recombination in the GaSb material system is also investigated.

Critique of “Planetary Normal Mode Computation: Parallel Algorithms, Performance, and Reproducibility” by SCC Team From ETH Zurich

This report analyzes the reproducibility of the article “Computing Planetary Interior Normal Modes with A Highly Parallel Polynomial Filtering Eigensolver” by Jia Shi et al. (Shi, 2018). To reproduce the results we perform different weak and strong scaling studies using a series of Mars models. All experimental runs were performed during the SC19 Student Cluster Competition on a four node Intel Skylake cluster. We show that the findings of the original article can be reproduced in a different environment.

Editorial: SESMO Special Issues

As the journal nears the end of its second official year, we are pleased to start accepting submissions to our first two Special Issues. The first Special Issue is on Resilience of complex coupled Socio-Technical-Environmental systems through the modeling lens with guest editors Tatiana Filatova, Tina Comes (4TU Resilience Engineering Centre), Christoph Hoelscher (ETH Zurich) and Juliet Mian (Resilence Shift). This Special Issue aims to bring together cutting-edge research and international practice to offer insights into the latest scientific modelling methods, gaps, challenges and opportunities and best practice examples relating to operationalising resilience across a range of socio-technical-environmental applications. The second Special Issue is on Large-scale behavioural models of land use change with guest editors Calum Brown (Karlsruhe Institute of Technology), Tatiana Filatova (University of Twente), Birgit Müller (Helmholtz Centre for Environmental Research – UFZ), and Derek Robinson (University of Waterloo). This Special Issue is focussed on better understanding and modelling of temporal or spatial scales in land use dynamics.&#x0D; &#x0D; We invite new proposals for Special Issues that fit within SESMO’s aims and scope. Our Special Issues are cohesive collections of articles focussed on a specific contemporary theme related to socio-environmental systems modelling. The Special Issue can build on previous work and research gaps, but can also explore new and emerging terrain relevant to our aims. Although the conceptualisation of a Special Issue may be initiated in a conference or workshop, it is critical that such a proposal also builds on the original dialogue. Articles should also be canvassed from across the globe. SESMO is an open access journal with no article processing or publication charges for authors. If you have a topic to propose, please contact us to discuss further.

COVID-19 as a chance for hybrid teaching concepts.

COVID-19 has turned the 2020 spring semester upside down. Three days before the start of the block week of the “Teamwork” module, the Federal Office of Public Health (FOPH) announced the ban on live interaction, which made it impossible to conduct five days of practice in the simulation centre of the University Hospital of Zurich. But how can the teaching of all the learning objectives necessary for medical training be guaranteed during an exceptional situation with constantly changing conditions? In the case of the BSc Human Medicine at ETH Zurich (ETHZ), the answer is: Hybrid teaching.The field report “COVID-19 as a chance for hybrid teaching concepts” outlines how ETHZ switched to hybrid teaching within a very short time and how hospital placements were combined with video conferences. The qualitative surveys conducted at the end of the semester and the weekly quantitative surveys of students from March to June indicate the importance of personal exchange despite the ban on contact and that interactivity is possible even without physical proximity. An example from the autumn semester will also be used to show which aspects have proved to be successful and can therefore be retained.

Dataset from the shake table tests of a rocking podium structure

Conventional validation of analytical and numerical models in Earthquake Engineering involves the comparison of numerically simulated response time histories to experimentally obtained benchmark responses to the same earthquake excitations. As the seismic design problem is inherently stochastic, an alternative, statistical, and easier-to-pass validation procedure has been suggested. As an example, numerical and analytical models may fail to predict the planar rocking response of a rigid block to a specific ground motion, but they can be proven quite successful in predicting the statistical distribution of the maxima of that response to an ensemble of ground motions. This article describes the publicly available data obtained from a series of 226 shake table tests of a 3D rocking podium structure, designed at ETH Zurich and carried out at EQUALS Lab, University of Bristol. This well-documented dataset is the largest one involving a shake table and can be used to statistically validate analytical and numerical models of rocking structures.

Interview with Beat Signer

Beat Signer is Professor of Computer Science at the Vrije Universiteit Brussel (VUB) and co-director of the Web &amp; Information Systems Engineering (WISE) research lab. He received a PhD in Computer Science from ETH Zurich where he has also been leading the Interactive Paper lab as a senior researcher for four years. He is an internationally distinguished expert in cross-media technologies and interactive paper solutions. His further research interests include human-information interaction, document engineering, data physicalisation, mixed reality as well as multimodal interaction. He has published more than 100 papers on these topics at international conferences and journals, and received multiple best paper awards. Beat has 20 years of experience in research on cross-media information management and multimodal user interfaces. As part of his PhD research, he investigated the use of paper as an interactive user interface and developed the resource-selector-link (RSL) hypermedia metamodel. With the interactive paper platform (iPaper), he strongly contributed to the interdisciplinary European Paper++ and PaperWorks research projects and the seminal research on paper-digital user interfaces led to innovative cross-media publishing solutions and novel forms of paper-based human-computer interaction. The RSL hypermedia metamodel is nowadays widely applied in his research lab and has, for example, been used for cross-media personal information management, an extensible cross-document link service, the MindXpres presentation platform as well as in a framework for cross-device and Internet of Things applications. For more details, please visit https://beatsigner.com.

Pre-Culture of Human Mesenchymal Stromal Cells in Spheroids Reduces Hypertrophic Differentiation &lt;i&gt; in vitro&lt;/i&gt; and Facilitates Chondrogenesis at a Low Total Cell Count Upon Embedding in Biomaterials

Material assisted cartilage tissue engineering approaches have limited application in cartilage treatment due to hypertrophic and fibrocartilaginous tissue formation and the high cell count needed. The aim of this study was to investigate the potential of human mesenchymal stromal cell (hMSC) spheroids embedded in biomaterials to study the effect of biomaterial composition on cell differentiation. hMSCs were pre-cultured in spheroids (250 cells/spheroid) for three days in chondrogenic differentiation media. Spheroids were embedded in tyramine-modified hyaluronic acid (THA) and collagen type I (Col) composite hydrogels at four combinations of THA (12.5 vs 16.7 mg/ml) and Col (2.5 vs 1.7 mg/ml) content at a cell density of 5 Mio cells/ml (1’000 spheroids/sample). Macro-pellets derived from hMSCs (250’000 cells, MP) or hMSC spheroids (250’000 cells/1’000 spheroids, SP) served as controls. hMSCs differentiation (day 21) was analyzed using quantification of glycosaminoglycans (GAGs), gene expression analysis and (immuno-) histological stainings. Embedding of hMSC spheroids in THA-Col biomaterials induced chondrogenic differentiation marked by upregulation of aggrecan (ACAN) and COL2A1, and production of GAGs. A lower THA content led to a more pronounced chondrogenic phenotype compared to a higher THA content. Col content had no significant influence on hMSC chondrogenesis. Pellet cultures (MP, SP) showed an upregulation in chondrogenic-associated genes and production of GAGs with less upregulation of hypertrophic-associated genes in MP culture compared to SP group.This study indicated a positive benefit of pre-culturing hMSCs in spheroids with respect to hypertrophic gene expression compared to the gold standard pellet culture without compromising chondrogenic matrix production. Funding: This work is part of the osteochondral defect collaborative research program supported by the AO Foundation. F.S. received the AO Foundation Fellowship in Health Sciences and Technology from ETH Zurich Foundation. Declaration of Interests: The authors have no competing of interests. Ethics Approval Statement: Full ethical approval (Inselspital Bern - Bern Req-2016-00141, University hospital Freiburg - EKFreiburg: 135/14).

How has external knowledge contributed to lithium-ion batteries for the energy transition?

SummaryInnovation in clean-energy technologies is central toward a net-zero energy system. One key determinant of technological innovation is the integration of external knowledge, i.e., knowledge spillovers. However, extant work does not explain how individual spillovers come about: the mechanisms and enablers of these spillovers. We ask how knowledge from other technologies, sectors, or scientific disciplines is integrated into the innovation process in an important technology for a net-zero future: lithium-ion batteries (LIBs), based on a qualitative case study using extant literature and an elite interview campaign with key inventors in the LIB field and R&D/industry experts. We identify the breakthrough innovations in LIBs, discuss the extent to which breakthrough innovations—plus a few others—have resulted from spillovers, and identify different mechanisms and enablers underlying these spillovers, which can be leveraged by policymakers and R&D managers who are interested in facilitating spillovers in LIBs and other clean-energy technologies.

Diseño, Construcción y Capacidades del Large Universal Shell Element Tester

El Large Universal Shell Element Tester (LUSET) es un nuevo dispositivo de ensayos, desarrollado en la ETH Zúrich, el cual facilita el estudio del comportamiento mecánico, a escala real, de elementos lámina de hormigón armado sujetos a solicitaciones en sus tres dimensiones (esfuerzos combinados de elementos tipo losa y membrana). En este artículo se presentan los motivos que condujeron al desarrollo del LUSET y, adicionalmente, se describen sus componentes, el software de control y los sistemas de medición. Finalmente, se presenta una breve descripción de la serie de ensayos usada para validar la funcionalidad del LUSET, así como, un resumen de sus posibilidades.

The language centre as a laboratory for innovation

Abstract This paper discusses the potential of language centres in higher education as laboratories for innovation. Despite their hybrid character as central service providers that are also defined by their teaching, their positioning at the academic periphery, and the lack of a mandate to do academic research, language centres still have an obligation to conduct research as a means of promoting innovation. The design-based research (DBR) approach in learning and teaching, in which teaching stakeholders examine learning processes in real situation, offers a suitable opportunity for language centres to overcome the restrictions placed upon them. DBR can be done using existing resources and the innovation potential of a language centre’s teaching staff. The leadership and management of the language centre must be made responsible for providing and/or enabling the necessary structural, material, and cultural conditions for such research. This paper discusses the DBR approach at language centres in higher education and its impact on leadership. It then gives two examples of the successful implementation of DBR at the Language Center of UZH and ETH Zurich.

Integrating systems and design thinking in transdisciplinary case studies

In the new Bachelor-level courseUmweltproblemlösen (Tackling environmental problems), a part of ETH Zurich’s Environmental Sciences Bachelor’s programme, we teach students to zoom in on elements of practice (design thinking) and to zoom out on the whole system (systems thinking). Participants take stakeholders’ interests and needs into account and prepare possible measures, thus developing transformation knowledge and anticipating their future role as transdisciplinary sustainability scientists.Umweltproblemlösen (Tackling environmental problems)is a Bachelor-level course that carries on a long tradition of transdisciplinary (td) case studies in the Environ mental Sciences curriculum at ETH Zurich. Td case studies introduce students to key features of transdisciplinarity. Two corres ponding learning goals of the case studies are 1. to not only analyse problems, but to also suggest solutions, and 2. to take the complexity of the tackled socio-ecological system into account. In the new course we address both learning goals by integrating systems and design thinking. We present this approach in detail to show how features of transdisciplinarity are transferred to learning contexts. We compare it to the approaches of other td case studies by asking how each interprets and addresses the two learning goals. The comparison shows that the case study approaches implicitly impart different ideas about how a td environmental scientist should support societal problem solving. A key difference to previous approach es is that the new course asks students to enter deeply into the world of practice and the stakeholders’ divergent needs.

Forecasting Financial Crashes: A Dynamic Risk Management Approach

Since 2009, stock markets have resided in a long bull market regime. Passive investment strategies have succeeded during this low-volatility growth period. From 2018 on, however, there was a transition into a more volatile market environment interspersed by corrections increasing in amplitude and frequency. This calls for more adaptive dynamic risk management strategies, as opposed to static buy-and-hold strategies. To hedge against market drawdowns, the greatest source of risk that should accurately be estimated is crash risk. This article applies the Log-Periodic Power Law Singularity (LPPLS) model of endogenous asset price bubbles to monitor crash risk. The model is calibrated to 15 years market history for five relevant equity country indices. Particular emphasis is put on the US S&P 500 Composite Index and the recent market history of the year 2020. The results show that relevant historical bubble events, including the Corona crash, could be detected with the model and derived indicators. Many of these events were predicted in advance in monthly reports by the Financial Crisis Observatory (FCO) at ETH Zurich. The Corona crash, as the most recent event of interest, is discussed in further detail. Our conclusion is that unsustainable price dynamics leading to an unstable bubble, fuelled by quantitative easing and other policies, already existed well before the pandemic started. Thus, the bubble bursting in February 2020 as a reaction to the Corona pandemic was of endogenous nature and burst in response to the exogenous Corona crisis, which was predictable to some degree based on the endogenous price dynamics. Following the crash, a fast recovery of the price to pre-crisis levels ensued in the following months. This lets us conclude that, as long as the underlying origins and the macroeconomic environment that created this bubble do not change, the bubble will continue to grow and potentially spread to other sectors. This may cause even more hectic market behaviour, overreaction and volatile corrections in the future.

Finite element analysis of the seismic shake‐table response of a rocking podium structure

AbstractRocking podium structures consist of rocking columns supporting a platform to achieve kinematic seismic isolation of the superstructure above. This article presents detailed finite element (FE) analysis modeling and results of the benchmark rocking podium structure that was tested as part of a blind prediction contest organized by the Pacific Earthquake Engineering Research center (PEER) at UC Berkeley, the University of Bristol, and ETH Zurich in 2019. Details of the FE modeling approach, as well as a discussion on key results and findings of this study are outlined herein. It was found that the FE model of the rocking podium structure was not sensitive to the element type, mesh layout or maximum time step, while the choice of contact algorithm influences the stability of the predicted rocking behavior. Modeling of the friction interactions between the rocking interfaces also had a nontrivial influence on the dynamic rocking response as it represented the main source of energy dissipation in the system. Further, instead of assuming an arbitrary value for inherent damping which was deemed to be very low for such a structure, explicit modeling of the frictional dissipation mechanism at the column‐to‐podium interface was preferred in this study.

From organic chemistry to chemical biology via macromolecules with Hermann Staudinger

Hermann Staudinger was born in Worms, Germany on March 23, 1881 and studied chemistry at University of Halle, Technical University, Darmstadt and Ludwig Maximillian University, Munich. In 1903 when he was only 22 years old, he obtained his PhD in Chemistry with Daniel Vorlaender in Halle. He started his habilitation with J. Thiele at the University of Strasbourg where in 1905, at age 25 he reported the discovery of ketenes. In 1907 at age 26 he discovered the [2 + 2] cycloaddition of ketenes with imines. This reaction remains even today the method of choice for the synthesis of β-lactams the main building block of antibiotics. This reaction is known as the Staudinger synthesis. In 1907 he obtained his habilitation in Strasbourg and moved as a junior faculty to the Technical University in Karslruhe. In Karslruhe he became for the first time interested in polymers. In 1912 he moved as professor of organic chemistry at Swiss Federal Institute of Technology in Zurich (ETH Zurich) where in 1919 he discovered the reduction of azides with triphenylphosphine, known as the Staudinger reaction. In 1920, at age 39 and at the pick of his professional career as an organic chemist he published a paper claiming that natural and synthetic polymers are covalently linked macromolecules. He had no support for this concept. In 1953 he received Nobel Prize in chemistry “for his discoveries in the field of macromolecular chemistry.” As seen even from Nobel lecture, his ultimate dream was to bridge between synthetic macromolecules and biology. His dream came through in the year 2000 when Bertozzi, Raines and Kiessling discovered Staudinger ligation, a bioorthogonal reaction that allows chemistry in living systems. His dream did not come through by bridging between synthetic macromolecules and biology but by transforming Staudinger reaction into Staudinger ligation.