| 1. |
- Thomas, Richard D., et al.
(författare)
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DESIREE : Physics with cold stored ion beams
- 2015
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Ingår i: DR2013. - : EDP Sciences. ; 84, s. 01004-01004
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Konferensbidrag (refereegranskat)abstract
- Here we will briefly describe the commissioning of the Double ElectroStatic Ion Ring ExpEriment (DESIREE) facility at Stockholm University, Sweden. This device uses purely electrostatic focussing and deflection elements and allows ion beams of opposite charge to be confined under extreme high vacuum and cryogenic conditions in separate rings and then merged over a common straight section. This apparatus allows for studies of interactions between cations and anions at very low and well-defined centre-of-mass energies (down to a few meV) and at very low internal temperatures (down to a few K).
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| 2. |
- Podgorski, Krzysztof, et al.
(författare)
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Distributions of spatial wave size for random fields
- 2016
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Ingår i: 2nd International Conference on Event-Based Control, Communication, and Signal Processing (EBCCSP), Krakow, POLAND, JUN 13-15, 2016. - 9781509041961
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Konferensbidrag (refereegranskat)abstract
- A method of measuring three-dimensional spatial wave size is proposed and statistical distributions of the size characteristics are derived in explicit integral forms for Gaussian sea surfaces. New definitions of wave characteristics such as the crest-height, the length, the size and the wave front location are provided in fully dimensional context. The joint statistical distributions of these wave characteristics are derived using the Rices formulas for expected numbers of local maximum and distance from a local maximum to a level crossing countour. %The methodology will be also illustrated by some examples from other type of engineering applications. Review of the Rice's method to study crossing distributions is given.
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| 3. |
- Berntsson Svensson, Richard, 1978, et al.
(författare)
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A Case Study Evaluation of the Guideline-Supported QUPER Model for Elicitation of Quality Requirements
- 2015
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Ingår i: Requirements Engineering: Foundation for Software Quality. - Cham : Springer-Verlag Berlin. - 0302-9743 .- 1611-3349. - 9783319161013 - 9783319161006 ; 9013, s. 230-246
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Konferensbidrag (refereegranskat)abstract
- For market-driven software product developing organizations operating on a competitive open market, it is important to plan the product's releases so that they can reach the market as early as possible with a competitive level of quality compared to its competitors' products. Hence, quality requirements can be seen as a key competitive advantage. The QUPER model was developed with the aim to support high-level decision-making in release planning of quality requirements. As a follow up on previous studies on QUPER, this study investigates: What are practitioners' views on the utilities of QUPER extended with guidelines including domain-specific examples? [Principal ideas/results] In the presented case study, a set of detailed guidelines of how to apply QUPER in practice, including how to handle cost dependencies between quality requirements, was evaluated at a case company in the mobile handset domain with 24 professionals using real quality requirements. The results point to the importance of having concrete guidelines combined with instructive examples from real practice, while it is not always obvious for a practitioner to transfer cost-dependency examples into the domains that are different from the example domain. The transferability of guidelines and examples to support methodology adoption is an interesting issue for further research.
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| 4. |
- Wiqvist, Samuel, et al.
(författare)
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Partially Exchangeable Networks and architectures for learning summary statistics in Approximate Bayesian Computation
- 2019
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Ingår i: Proceedings of the 36th International Conference on Machine Learning. - : PMLR. ; 2019-June, s. 11795-11804
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Konferensbidrag (refereegranskat)abstract
- We present a novel family of deep neural architectures, named partially exchangeable networks (PENs) that leverage probabilistic symmetries. By design, PENs are invariant to block-switch transformations, which characterize the partial exchangeability properties of conditionally Markovian processes. Moreover, we show that any block-switch invariant function has a PEN-like representation. The DeepSets architecture is a special case of PEN and we can therefore also target fully exchangeable data. We employ PENs to learn summary statistics in approximate Bayesian computation (ABC). When comparing PENs to previous deep learning methods for learning summary statistics, our results are highly competitive, both considering time series and static models. Indeed, PENs provide more reliable posterior samples even when using less training data.
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| 5. |
- Podgorski, Krzysztof, et al.
(författare)
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Distributions at random events
- 2016
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Ingår i: 2016 2ND INTERNATIONAL CONFERENCE ON EVENT-BASED CONTROL, COMMUNICATION, AND SIGNAL PROCESSING (EBCCSP). - 9781509041961 ; , s. 1-8
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Konferensbidrag (refereegranskat)abstract
- We discuss the generalized Rice formula approach to deriving long-run distributions of characteristics defined at random events of a stochastic process or field. The approach stems from the same principle originally introduced by Rice for the level crossing intensity in a random signal and we review its extensions to more general contexts.Events are defined on random surfaces through crossing levels of (multivariate) stochastic fields.We also account for the dynamics of spatial-temporal fields using observed velocities. Extensions beyond the Gaussian model are shown and models for sampling from the level crossing distributions are presented.The importance of these generalizations for applications is illustrated through examples.
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| 6. |
- Alvén, Jennifer, 1989, et al.
(författare)
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A Deep Learning Approach to MR-less Spatial Normalization for Tau PET Images
- 2019
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Ingår i: Medical Image Computing and Computer Assisted Intervention : MICCAI 2019 - 22nd International Conference, Proceedings - MICCAI 2019 - 22nd International Conference, Proceedings. - Cham : Springer International Publishing. - 1611-3349 .- 0302-9743. - 9783030322441 - 9783030322458 ; 11765 LNCS, s. 355-363
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Konferensbidrag (refereegranskat)abstract
- The procedure of aligning a positron emission tomography (PET) image with a common coordinate system, spatial normalization, typically demands a corresponding structural magnetic resonance (MR) image. However, MR imaging is not always available or feasible for the subject, which calls for enabling spatial normalization without MR, MR-less spatial normalization. In this work, we propose a template-free approach to MR-less spatial normalization for [18F]flortaucipir tau PET images. We use a deep neural network that estimates an aligning transformation from the PET input image, and outputs the spatially normalized image as well as the parameterized transformation. In order to do so, the proposed network iteratively estimates a set of rigid and affine transformations by means of convolutional neural network regressors as well as spatial transformer layers. The network is trained and validated on 199 tau PET volumes with corresponding ground truth transformations, and tested on two different datasets. The proposed method shows competitive performance in terms of registration accuracy as well as speed, and compares favourably to previously published results.
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| 7. |
- Örnhag, Marcus Valtonen, et al.
(författare)
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Planar motion bundle adjustment
- 2019
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Ingår i: ICPRAM 2019 - Proceedings of the 8th International Conference on Pattern Recognition Applications and Methods. - : SCITEPRESS - Science and Technology Publications. - 9789897583513 ; , s. 24-31
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Konferensbidrag (refereegranskat)abstract
- In this paper we consider trajectory recovery for two cameras directed towards the floor, and which are mounted rigidly on a mobile platform. Previous work for this specific problem geometry has focused on locally minimising an algebraic error between inter-image homographies to estimate the relative pose. In order to accurately track the platform globally it is necessary to refine the estimation of the camera poses and 3D locations of the feature points, which is commonly done by utilising bundle adjustment; however, existing software packages providing such methods do not take the specific problem geometry into account, and the result is a physically inconsistent solution. We develop a bundle adjustment algorithm which incorporates the planar motion constraint, and devise a scheme that utilises the sparse structure of the problem. Experiments are carried out on real data and the proposed algorithm shows an improvement compared to established generic methods.
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| 8. |
- Carlsson, Håkan, 1973, et al.
(författare)
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General User Surveys and Other Methods for Quality Assessment – User Knowledge and Evidence-Based Library Development
- 2019
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Ingår i: 10th International Evidence Based Library and Information Practice Conference EBLIP, 16-19 June 2019 Glasgow, Scotland, University of Strathclyde.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Aim A key component of library management is meeting the needs of our users. This requires continuous analysis of user experience followed by library development. The aim of this study was to better understand the use and effect of general user surveys (GUS) and other methods of gathering user input for quality assessment and improvement of library activities. Methods Data collection was done via surveys, which were sent out to the library directors of all 308 European LIBER university libraries. The response rate was 42%. After survey collection the free-text answers were coded and categorised and then the results were analysed. Results A majority of the responding libraries (77%) have performed a GUS during the last four years. Of these libraries, 54% reported changes to services based on the surveys. The most common method of obtaining user input was by placing a digital “user suggestion box” on the library website. The next most common method entailed using systematic processes to ensure continuous quality improvements. Discussion/conclusion Nearly half of libraries develop their own survey instruments. Appropriate follow-up after the survey was important in order to assure library development. The key step was producing a written report, which increased success in changes to services by nearly 50%. Changes were observed in all traditional library areas, with most changes reported for the areas of physical library standard, communication/marketing and quality of information literacy education. The changes implemented were typically small steps leading to substantial improvements, rather than larger strategic shifts. Small libraries have limited resources and difficulty arranging large user surveys. They reported higher usage of methods performed in the physical library. The library strengths most valued by users were in the areas of the physical library, researcher support- especially in the area of scholarly communication- and information literacy education. User feedback helps build institutional profile and image. Analysis of the different methods revealed information regarding which methods give the best understanding of the users.
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| 9. |
- Carlsson, Håkan, 1973, et al.
(författare)
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User Knowledge Management – How University Libraries Analyse User Needs and Develop Services
- 2018
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Ingår i: Proceedings of the 39th annual IATUL conference.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The demands on library services are quickly changing in a continually updating digital age. This increases the importance of a good understanding of the needs and demands of the users. In order to sample and follow the change in user needs library organisations analyse their efforts using a series of different methods. In a recent survey distributed to all 301 European LIBER university libraries, we asked questions pertaining to methods for quality development, particularly implementation of general user surveys (GUS). Among the 127 answering libraries (42%) we analysed how library services can be developed via a user-centred approach. In general, libraries engaged in explorative methods, such as UX techniques or process mapping, displayed an increased understanding of what the users find as library strengths. On the other hand libraries using primarily reporting tools such as balanced scorecard showed little or no such effect. The library strengths most valued by users in the study were in the areas of the physical library, researcher support - especially in the area of scholarly communication - and information literacy tuition. Several answers indicate that user feedback has helped build institutional profile and image. The results also give an indication of how general user surveys can best be used. Appropriate follow-up after the survey is important in gaining usable results. The key step was the production of a written report, which resulted in a nearly 50% increased chance of obtaining changes in services. Most libraries developed their own surveys for the effort. Services most commonly changed after performing a GUS were in the areas of the physical library, followed by communication/marketing and information literacy tuition. A GUS most often leads to a number of minor service improvements rather than large strategic shifts. This work was commissioned and supported by the former LIBER Working Group on Research and Education.
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| 10. |
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