| 1. |
- Kim, Kyung Hwan, et al.
(författare)
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Anisotropic X-Ray Scattering of Transiently Oriented Water
- 2020
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Ingår i: Physical Review Letters. - : American Physical Society (APS). - 0031-9007 .- 1079-7114. ; 125:7
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Tidskriftsartikel (refereegranskat)abstract
- We study the structural dynamics of liquid water by time-resolved anisotropic x-ray scattering under the optical Kerr effect condition. In this way, we can separate the anisotropic scattering decay of 160 fs from the delayed temperature increase of similar to 0.1 K occurring at 1 ps and quantify transient changes in the O-O pair distribution function. Polarizable molecular dynamics simulations reproduce well the experiment, indicating transient alignment of molecules along the electric field, which shortens the nearest-neighbor distances. In addition, analysis of the simulated water local structure provides evidence that two hypothesized fluctuating water configurations exhibit different polarizability.
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| 2. |
- Mariedahl, Daniel, et al.
(författare)
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X-ray Scattering and O-O Pair-Distribution Functions of Amorphous Ices
- 2018
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 122:30, s. 7616-7624
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Tidskriftsartikel (refereegranskat)abstract
- The structure factor and oxygen-oxygen pair distribution functions of amorphous ices at liquid nitrogen temperature (T = 77 K) have been derived from wide-angle X-ray scattering (WAXS) up to interatomic distances of r = 23 angstrom, where local structure differences between the amorphous ices can be seen for the entire range. The distances to the first coordination shell for low-, high-, and very-high-density amorphous ice (LDA, HDA, VHDA) were determined to be 2.75, 2.78, and 2.80 angstrom, respectively, with high accuracy due to measurements up to a large momentum transfer of 23 angstrom(-1). Similarities in pair-distribution functions between LDA and supercooled water at 254.1 K, HDA and liquid water at 365.9 K, and VHDA and high-pressure liquid water were found up to around 8 angstrom, but beyond that at longer distances, the similarities were lost. In addition, the structure of the high-density amorphous ices was compared to high-pressure crystalline ices IV, IX, and XII, and conclusions were drawn about the local ordering.
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| 3. |
- Perakis, Fivos, et al.
(författare)
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Diffusive dynamics during the high-to-low density transition in amorphous ice
- 2017
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 114:31, s. 8193-8198
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Tidskriftsartikel (refereegranskat)abstract
- Water exists in high- and low-density amorphous ice forms (HDA and LDA), which could correspond to the glassy states of high(HDL) and low-density liquid (LDL) in the metastable part of the phase diagram. However, the nature of both the glass transition and the high-to-low-density transition are debated and new experimental evidence is needed. Here we combine wide-angle X-ray scattering (WAXS) with X-ray photon-correlation spectroscopy (XPCS) in the small-angle X-ray scattering (SAXS) geometry to probe both the structural and dynamical properties during the high-to-low-density transition in amorphous ice at 1 bar. By analyzing the structure factor and the radial distribution function, the coexistence of two structurally distinct domains is observed at T = 125 K. XPCS probes the dynamics in momentum space, which in the SAXS geometry reflects structural relaxation on the nanometer length scale. The dynamics of HDA are characterized by a slow component with a large time constant, arising from viscoelastic relaxation and stress release from nanometer-sized heterogeneities. Above 110 K a faster, strongly temperature-dependent component appears, with momentum transfer dependence pointing toward nanoscale diffusion. This dynamical component slows down after transition into the low-density form at 130 K, but remains diffusive. The diffusive character of both the high- and low-density forms is discussed among different interpretations and the results are most consistent with the hypothesis of a liquid-liquid transition in the ultraviscous regime.
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| 4. |
- Amann, Daniel, 1967-, et al.
(författare)
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Affordability aspects in the concept generation of defence systems
- 2017
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Ingår i: Proceedings of 18th International CINet Conference. - Twente : Continuous Innovation Network. - 9789077360200 ; , s. 26-38
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Cost escalation for fighter aircraft is arguably not sustainable. Pushing frontiers oftechnology by incremental improvements of traditional platforms has led to anexponential increase in cost. This paper addresses the process of concept generationwith the purpose to explore how affordability is managed in that process, in order toidentify possible measures to improve the likelihood of generating affordableconcepts. This is done by studying two cases of concept generation of future combatair systems. The concepts generated in these two cases are however not curbing thecost escalation and are, with only one notable exception, based on incrementalinnovation. Nevertheless, the empirical observations offer leads to potentially fostera more innovative and cost conscious concept generation process, indicatingavenues for future research.
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| 5. |
- Amann, Daniel, Doktorand, et al.
(författare)
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Affordability Aspects in the Development of Defence Equipment : Case Studies of Concept Generation in the Defence Industry
- 2021
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Ingår i: Defence and Peace Economics. - : Informa UK Limited. - 1024-2694 .- 1476-8267. ; 32:7, s. 847-863
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Tidskriftsartikel (refereegranskat)abstract
- Cost escalation for many complex defence equipment is arguably not sustainable. Customer driven requirements have led to an exponential increase in costs by pushing frontiers of technology to support primarily incremental improvements of traditional equipment concepts. Accordingly, affordability has become a more discussed subject indefence acquisition. This paper addresses the process of generating complex defence equipment concepts. The purpose is to explore how affordability is managed in that process and to identify possible leads to how an unsustainable cost escalation for this type of equipment can be curbed. This is done by studying two cases of concept generation of future combat air equipment systems from a company process perspective. This applied micro perspective on cost escalation showed that none of the concepts generated in these two cases were assessed to curb the cost escalation. Further, the innovation model for the generated concepts, with only one notable exception, was incremental. Nevertheless, the empirical observations from these two cases offer leads on how to potentially foster a more innovative and affordability-oriented concept generation process for future defence equipment, as well as indicating avenues for future research.
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| 6. |
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| 7. |
- Amann, Daniel, Doktorand
(författare)
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Changing Path and Curbing Cost Escalation : Lessons Learnt from the Gripen Case
- 2022
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Ingår i: Defence and Peace Economics. - : Informa UK Limited. - 1024-2694 .- 1476-8267. ; 33:4, s. 421-437
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Tidskriftsartikel (refereegranskat)abstract
- Extant theory suggests that paths of development, although identified as being unsustainable, might be difficult to depart from. The aim of this study has therefore been to explore and understand how a path change can be facilitated in a setting of complex product systems. A unique single case of product development that managed to curb an unsustainable intergenerational cost escalation for complex defence equipment has been studied. The study shows a relation between a path change and a challenging opportunity, and also indicates how this relation can be moderated by the company management and the customers. The study provides both theoretical and practical implications, supporting understanding and facilitation of path changes.
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| 8. |
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| 9. |
- Amann, Daniel, et al.
(författare)
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DISRUPTIVE INNOVATION IN COMPLEX PRODUCT SYSTEMS (COPS) : INFLUENCING CHARACTERISTICS AND CONDITIONS
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Complex product systems (CoPS) tend to get more complex for every new productgeneration, which for some product categories imply cumbersome escalating costs. Forthese products, promises of lowered costs by disruptive innovation certainly areappealing, but frequently deluding. Therefore, this paper aims at exploring specific CoPScharacteristics and conditions influencing companies’ propensity to develop disruptiveproducts, and to derive related managerial implications. This is performed by analysingfour case studies of CoPS product development in four different industrial sectors. Thestudy suggests that specific characteristics and conditions in the CoPS setting influenceproduct development management to aim at incremental improvements of earlier productconcepts, whereby disruptive innovations in reality rarely get a chance. Moreover, it isfound that barriers for disruptive innovation in CoPS classified as tournament goods areconsidered even higher, because this product category generally do not offer anyperformance oversupply.
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| 10. |
- Amann, Daniel, 1967-
(författare)
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Exploring affordability in concept generation for complex defence products
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- National defence budgets face pressure from intergenerational escalating costs for complex defence products, such as fighter aircraft and submarines. These escalating costs originate from ever-increasing performance requirements due to the competitive nature of warfare. In combat, only winning is good enough. Therefore, the products’ performance is considered crucial for gaining an edge over an opponent. As the continuous development of ever-costlier complex defence products is not sustainable, it is high time for a path change towards affordability, meaning less costly products without any compromises in terms of operational requirements. However, the fact that this cost escalation has long been recognised as unsustainable indicates that a path change towards affordability will not be easy to achieve. Such a path change will likely require radical changes in product concepts – even though costs might be reduced in other ways, product concepts are believed to have the greatest potential. In accordance with this assumption, this thesis suggest that the phenomenon of continuous generation of ever-costlier complex defence concepts is ultimately sealed in the front end of innovation, where opportunities are identified and product concepts are defined. Accordingly, this thesis aims to explore how firms and customers can influence activities in the front end of innovation in order to successfully manage the affordability of complex defence products. This aim is approached through phenomenon-driven research performed in a set of four concatenated studies, represented by five papers. By letting successive studies be informed by preceding studies, new knowledge and theory are added to this under-researched topic. Empirically, several factors and aspects influencing the front end of innovation are identified as potential barriers to or enablers of path changes towards affordability. In addition, different measures that companies and customers can adopt to support such path changes are proposed. The thesis contributes to extant theory by providing a definition of affordability adapted to complex defence products, and by contrasting affordability with established concepts and methods aimed at making products less costly. Furthermore, benefits and deficiencies in the industry’s handling of concept generation for complex defence products are highlighted from an affordability perspective, and the influence of specific characteristics on path changes towards affordability in relation to complex defence equipment is described and discussed. Finally, conditions supporting affordability related to opportunities, knowledge and motivations are described, and the benefits of providing those generating complex capability-oriented concepts with cost-related information are demonstrated.In addition to these contributions to theory, this thesis has several implications for the practice of companies and governmental customers. It highlights measures that these two sets of actors can take to shape conditions and, thereby, influence key activities in the front end of innovation to generate complex defence-product concepts that meet affordability criteria. These suggested measures constitute an embryo of an explicit approach to affordability management.
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