1,839 research outputs found
Measuring Risk Aversion Model-Independently
We propose a new method to elicit individuals' risk preferences. Similar to Holt and Laury
(2002), we use a simple multiple price-list format. However, our method is based on a general
notion of increasing risk, which allows classifying individuals as more or less risk-averse
without assuming a specic utility framework. In a laboratory experiment we compare both
methods. Each classies individuals almost identically as risk-averse, -neutral, or -seeking.
However, classications of individuals as more or less risk-averse dier substantially. Moreover,
our approach yields higher measures of risk aversion, and only with our method these
measures are robust toward increasing stakes
Measuring Risk Aversion Model-Independently
We propose a new method to elicit individuals' risk preferences. Similar to Holt and Laury (2002), we use a simple multiple price-list format. However, our method is based on a general notion of increasing risk, which allows classifying individuals as more or less risk-averse without assuming a specic utility framework. In a laboratory experiment we compare both methods. Each classies individuals almost identically as risk-averse, -neutral, or -seeking. However, classications of individuals as more or less risk-averse dier substantially. Moreover, our approach yields higher measures of risk aversion, and only with our method these measures are robust toward increasing stakes.Risk Aversion; Multiple Price-List; Elicitation; Laboratory Experiment; Holt and Laury Method; Mean Preserving Spreads; Non-EUT; Increasing Risk
Towards Improved Understanding of Mass Transport in Polymer Electrolyte Membrane Water Electrolysers
The advent of a global societal and governmental movement to curb climate change has put low-carbon technologies at the centre stage of public interest and scientific efforts. In the wake of rising concerns around the carbon footprint of personal mobility and the energy sector, the concept of a ‘Hydrogen Economy’ has experienced yet another rapid spur of popularity. Polymer electrolyte membrane water electrolysers (PEMWEs) are a promising candidate for large-scale hydrogen production, and improvements in the technology have led to increasingly high operational current densities exceeding 2 A cm-2, which requires adequate mass transport strategies to ensure sufficient supply of reactant and removal of products. Optimization and diagnosis of mass transport processes in PEMWEs has long been neglected despite its significance, but the amount of scientific literature has recently increased sharply. This thesis uses existing diagnostic tools to gather new insights into the processes within PEMWE flow channels and liquid-gas diffusion layers, aims at providing new low-cost diagnostic tools to accelerate the investigation of mass transport processes, and consequently deduces novel approaches to the design of PEMWEs components, cells, and stacks. Neutron and X-ray imaging are used to demonstrate the effect of liquid-gas diffusion layer microstructure on the water-gas distribution in a PEMWE, revealing significant inhomogeneity across the active area. Due to cost and accessibility issues around radiation imaging, acoustic methods are explored as alternative diagnostic tools. Acoustic emission is successfully demonstrated as an operando technique to monitor two-phase flow in the flow channels, detecting the transition from bubbly to slug flow. Bubbly flow is observed at the onset of electrochemical activity and low current densities, with a high number of small bubbles, while at higher current densities these small bubbles coalesce and form larger slug bubbles. Lastly, acoustic time-of-flight imaging is used to monitor the water-gas distribution in the liquid-gas diffusion layer and the flow channels, with results being consistent with expectations and previous results obtained via neutron imaging
Guiding Companies to Reduce Technostress: A Mixed-Methods Study Deriving Practice-Oriented Recommendations
Technostress is a major challenge for employees using information technology. Technostress research has revealed the causes, i.e. techno-stressors, and resulting adverse consequences for employees and companies. However, there is a lack of practical insights guiding companies on how to reduce technostress. To offer such practical insights, we follow a mixed-methods approach. The qualitative study bases on eleven expert interviews and reveals seven measures that reduce technostress. We then elaborate on these interview results with a quantitative study of 110 employees. The quantitative results reveal the degree to which the seven measures are useful to reduce specific techno-stressors. Our results show that although there are measures used in practice, none reduces all different techno-stressors. We complement existent theoretical technostress research by offering practice-oriented recommendations on how to reduce technostress. Based on the illustration of which measures are useful for which techno-stressors, practitioners can choose the measures that best fits their needs
Initiator-free photo-crosslinkable cellulose-based resists for fabricating submicron patterns via direct laser writing
Novel bifunctional cellulose diacetate derivatives were synthesized in order
to achieve bio-based photoresists, which can be structured by two-photon
absorption via direct laser writing (DLW) without the need to use a
photoinitiator. Therefore, cellulose diacetate is functionalized with thiol
moieties and olefinic or methacrylic side groups enabling thiol-conjugated
crosslinking. These cellulose derivatives are also photo-crosslinkable via UV
irradiation ( = 254 nm and 365 nm) without using an initiator
Utilizing the sensitization effect for direct laser writing in a novel photoresist based on the chitin monomer N-acetyl-D-glucosamine
The great flexibility of direct laser writing arises from the possibility to
fabricate precise three-dimensional structures on very small scales as well as
the broad range of applicable materials. However, there is still a vast number
of promising materials which are currently inaccessible requiring the
continuous development of novel photoresists. Here, a new bio-sourced resist is
reported which relies on the monomeric unit of chitin, N-acetyl-D-glucosamine,
expanding the existing plant-based biopolymer resists by a bio-based monomer
from the animal kingdom. In addition it is shown that combined use of two
photoinitiators is advantageous over the use of a single one. In our approach,
the first photoinitator is a good two-photon absorber at the applied
wavelength, while the second photoinitiator exhibits poor two-photon absorbtion
abilities, but is better suited for crosslinking of the monomer. The first
photoinitiator absorbs the light acting as a sensitizer and transfers the
energy to the second initiator, which subsequently forms a radical and
initializes the polymerization. This sensitization effect enables a new route
to utilize reactive photointiators with a small two-photon absorption
cross-section for direct laser writing without changing their chemical
structure
Investigating (sequential) unit asking: an unsuccessful quest for scope sensitivity in willingness to donate judgments
People exhibit scope insensitivity: Their expressed valuation of a problem is not proportionate with its scope or size. To address scope insensitivity in charitable giving, Hsee et al. (2013) developed the (Classical) Unit Asking technique, where people are first asked how much they are willing to donate to support a single individual, followed by how much they are willing to donate to support a group of individuals. In this paper, we explored the mechanisms, extensions, and limitations of the technique. In particular, we investigated an extension of the technique, which we call Sequential Unit Asking (SUA). SUA asks people a series of willingness-to-donate questions, in which the number of individuals to be helped increases in a stepwise manner until it reaches the total group size. Across four studies investigating donation judgments (total (Formula presented.)), we did not find evidence that willingness to donate (WTD) judgments to the total group increased with larger groups. Instead, our results suggest that Unit Asking (sequential or classical) increases donation amounts only through a single one-off boost. Further, we find evidence in three out of four studies that the SUA extension increases WTD judgments over Classical Unit Asking. In a fifth study ((Formula presented.)) using a contingent valuation design (instead of donation judgments), we find scope sensitivity using all asking techniques. We conclude that, while it is difficult to create scope sensitivity in WTD judgments, SUA should be considered a promising approach to increase charitable donations
In-Situ Characterization of Microstructural Changes in Alloy 718 during High-Temperature Low-Cycle Fatigue
Components made of nickel-based alloys are typically used for high-temperature applications because of their high corrosion resistance and very good creep and fatigue strength, even at temperatures around 1000 °C. Corrosive damage can significantly reduce the mechanical properties and the expected remaining service life of components. In the present study, a new method was introduced to continuously determine the change in microstructure occurring as a result of exposure to high temperature and cyclic mechanical loading. For this purpose, the conventional low-cycle fatigue test procedure was modified and a non-destructive, electromagnetic testing technique was integrated into a servohydraulic test rig to monitor the microstructural changes. The measured values correlate with the magnetic material properties of the specimen, allowing the microstructural changes in the specimen’s subsurface zone to be analyzed upon high-temperature fatigue. Specifically, it was possible to show how different loading parameters affect the maximum chromium depletion as well as the depth of chromium depletion, which influences the magnetic properties of the nickel-based material. It was also observed that specimen failure is preceded by a certain degree of microstructural change in the subsurface zone. Thus, the integration of the testing technology into a test rig opens up new possibilities for improved prediction of fatigue failure via the continuous recording of the microstructural changes
A spatial obesity risk score for describing the obesogenic environment using kernel density estimation: development and parameter variation
Defect thermodynamics and lattice site basicity of proton and mixed conducting oxides
The extent of hydration of acceptor doped proton conducting oxides, typically described by dissociative hydration
(1)
has been correlated to various materials properties such as cation electronegativityand is argued to reflect the oxides’ basicity. 1,2 The reaction is, however, amphoteric; lattice oxygen ions are protonated while oxygen vacancies are hydroxylated, suggesting that the extent of hydration rather is governed by the basicity of the lattice oxygen ions – and the acidity of the oxygen vacancies. Recently a number of mixed conducting perovskites with redox-active and typically more acidic elements on the perovskite\u27s B-site have been shown to protonate according to
(2)
indicating that the hydration properties of e.g. novel cathode materials can be tailored by optimizing the oxide ion and vacancy basicity/acidity.
In this contribution we introduce the oxides’ proton and hydroxide affinity (PA and HA) as a measure of the oxide ion basicity and vacancy acidity, respectively, and show how these parameters can be determined from first principles DFT calculations. The PA and HA, and thermodynamics of Eq. 1 are calculated for a selection of binary and perovskite structured oxides, and discussed in relation to the oxide’s electronic, structural and bonding properties. The calculated affinities of the binary oxides generally follow the expected periodic trends and are shown to correlated with the position of the O2p bonding states, reflecting the relationship between the oxide’s electronic structure and basicity. We furthermore assess a series of perovskite structured oxides and discuss correlations between their defect thermodynamics/ion affinities and electronic structure, basicity and A-O and B-O bond characteristics
The research leading to these results has received funding from the Research Council of Norway (Grant nᵒ 272797 “GoPHy MiCO”) through the M-ERA.NET Joint Call 2016.
[1] T. Norby, M. Widerøe, R. Glöckner and Y. Larring, Dalton Transactions, 19, (2004)
[2] K.D. Kreuer, Annu. Rev. Mater. Res. 33 (2003) 333–5
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