| 1. |
- Antonello, Riccardo, et al.
(author)
-
Hierarchical scaled–states direct predictive control of synchronous reluctance motor drives
- 2016
-
In: IEEE Transactions on Industrial Electronics. - 0278-0046 .- 1557-9948. ; 63:8, s. 5176-5185
-
Journal article (peer-reviewed)abstract
- This paper presents the design and experimental validation of a finite-state direct predictive control for synchronous reluctance motor drives. The main features are the hierarchical selection policy of the optimal voltage vector and the dynamic scaling of the voltage amplitude which keeps the current ripple limited even in presence of low switching frequencies, as required by medium and high-power applications. The implementation is simple, intuitive and low-demanding. The study is fully supported by experimental evidences.
|
|
| 2. |
- Cote, Laurent, et al.
(author)
-
Symplectic rigidity of fibers in cotangent bundles of open Riemann surfaces
- 2023
-
In: Mathematische Annalen. - : Springer. - 0025-5831 .- 1432-1807. ; 386, s. 1717-1751
-
Journal article (peer-reviewed)abstract
- We study symplectic rigidity phenomena for fibers in cotangent bundles of Riemann surfaces. Our main result can be seen as a generalization to open Riemann surfaces of arbitrary genus of work of Eliashberg and Polterovich on the Nearby Lagrangian Conjecture for T*R-2. As a corollary, we answer a strong version in dimension 2n = 4 of a question of Eliashberg about linking of Lagrangian disks in T*R-n, which was previously answered by Ekholm and Smith in dimensions 2n >= 8.
|
|
| 3. |
- Durbeej, Bo, et al.
(author)
-
Photodegradation of substituted stilbene compounds : what colors aging paper yellow?
- 2005
-
In: Journal of Physical Chemistry A. - : American Chemical Society (ACS). - 1089-5639 .- 1520-5215. ; 109:25, s. 5677-5682
-
Journal article (peer-reviewed)abstract
- Photodegradation of lignin is one of the major postprocessing problems in paper production, as this renders yellowing of the paper and reduced paper quality. In this study, we have explored the photochemical properties of substituted stilbene derivatives believed to be key chromophores in the photodegradation of lignin derived from cinnamyl alcohol. In particular, the present work focuses on the computation of UV/vis electronic absorption spectra for different methoxylated stilbenes and their proposed photodegradation products. All calculations were performed using the time-dependent formalism of density functional theory (TD-DFT) and the B3LYP hybrid functional. It is concluded that the methodology employed is capable of reproducing not only the overall spectra, but also subtle features owing to the effects of different substitution patterns. For the strongly absorbing first excited singlet state (HOMO LUMO excitation) of the methoxylated stilbenes, the calculated transition energies are, albeit somewhat fortuitously, in excellent agreement with experimental data. The light-induced yellowing indirectly caused by the presence of stilbenes can be rationalized in terms of the absorption spectra of the resulting photodegraded o-quinones, for which distinct transitions in the 420–500 nm region of the visible spectrum lacking prior to degradation are observed.
|
|
| 4. |
- Hossain, MF, et al.
(author)
-
Molecular Basis for the Interactions of Human Thioredoxins with Their Respective Reductases
- 2021
-
In: Oxidative medicine and cellular longevity. - : Hindawi Limited. - 1942-0994 .- 1942-0900. ; 2021, s. 6621292-
-
Journal article (peer-reviewed)abstract
- The mammalian cytosolic thioredoxin (Trx) system consists of Trx1 and its reductase, the NADPH-dependent seleno-enzyme TrxR1. These proteins function as electron donor for metabolic enzymes, for instance in DNA synthesis, and the redox regulation of numerous processes. In this work, we analysed the interactions between these two proteins. We proposed electrostatic complementarity as major force controlling the formation of encounter complexes between the proteins and thus the efficiency of the subsequent electron transfer reaction. If our hypothesis is valid, formation of the encounter complex should be independent of the redox reaction. In fact, we were able to confirm that also a redox inactive mutant of Trx1 lacking both active site cysteinyl residues (C32,35S) binds to TrxR1 in a similar manner and with similar kinetics as the wild-type protein. We have generated a number of mutants with alterations in electrostatic properties and characterised their interaction with TrxR1 in kinetic assays. For human Trx1 and TrxR1, complementary electrostatic surfaces within the area covered in the encounter complex appear to control the affinity of the reductase for its substrate Trx. Electrostatic compatibility was even observed in areas that do not form direct molecular interactions in the encounter complex, and our results suggest that the electrostatic complementarity in these areas influences the catalytic efficiency of the reduction. The human genome encodes ten cytosolic Trx-like or Trx domain-containing proteins. In agreement with our hypothesis, the proteins that have been characterised as TrxR1 substrates also show the highest similarity in their electrostatic properties.
|
|
| 5. |
|
|
| 6. |
- Karlgren, Jussi, et al.
(author)
-
Foreground and background text in retrieval
- 2002. - 1
-
Conference paper (peer-reviewed)abstract
- Our hypothesis is that certain clauses have foreground functions in text, while other clauses have background functions and that these functions are expressed or reflected in the syntactic structure of the clause. Presumably these clauses will have differing utility for automatic approaches to text understanding; a summarization system might want to utilize background clauses to capture commonalities between numbers of documents while an indexing system might use foreground clauses in order to capture specific characteristics of a certain document.
|
|
| 7. |
- Lundquist, Knut, 1933, et al.
(author)
-
THE STRUCTURE AND CONFORMATION OF LIGNIN AS JUDGED BY X-RAY CRYSTALLOGRAPHIC INVESTIGATIONS OF LIGNIN MODEL COMPOUNDS: ARYLGLYCEROL β-SYRINGYL ETHERS
- 2009
-
In: BioResources. - 1930-2126 .- 1930-2126. ; 4:2, s. 529-536
-
Journal article (peer-reviewed)abstract
- Structural elements of the arylglycerol β-syringyl ether type are very frequent in hardwood lignins. A variety of crystalline dimeric lignin models representing different diastereomeric forms of structural elements in lignin of this type have been studied using X-ray crystallography. Bond distances and bond angles in the model compounds are in all probability nearly identical with those of the corresponding structural elements in lignins. Special attention was paid to the geometry of the β-O-syringyl linkage, since the reactivity of this linkage is of particular interest in connection with pulping reactions. The crystal structures of the model compounds suggest that two types of conformations are predominating; in both of them the aromatic rings are separated by ca. 4.5 Å (maximal distance 4.9-5 Å). Based on X-ray crystallographic data from four compounds a sequence of units (5 aromatic rings, 8 chiral C-atoms) attached to each other by β-syringyl ether linkages was constructed. The appearance of the resulting oligomer illustrates that stereoisomerism can be expected to influence the shape of the lignin molecules to a great extent.
|
|
| 8. |
- Simmons, Aaron T., et al.
(author)
-
Environmental consequences of a consumer shift from dairy- to soy-based products
- 2024
-
In: Crop and Pasture Science. - : CSIRO Publishing. - 1836-0947 .- 1836-5795. ; 75:1
-
Journal article (peer-reviewed)abstract
- Context. Climate change and water scarcity are global challenges facing humanity. Animal agriculture generates considerable greenhouse gas (GHG) emissions and consumes large volumes of water from rivers, streams and lakes. Reducing consumption of animal agricultural products with a relatively high carbon or water footprint, such as dairy, is often promoted as a mechanism to reduce the environmental impacts of food production. Attributionally-based footprints do not, however, assess the consequences of a change in demand for a product. Aims. This study aimed to assess the water and climate change consequences of replacing NSW dairy production, and co-products of dairy production, with plant-based alternatives. Methods. Process-based consequential life cycle assessment was used. Key results. Water savings associated with the change would be limited and GHG emissions reductions would be ~86% of that as estimated by the carbon footprint of production. When NSW dairy production was replaced with soy-based alternatives and two GHG emissions reduction strategies were implemented across the industry, namely enteric methane inhibitors and flaring methane from effluent ponds, GHG emissions increased by 0.63 Mt carbon dioxide equivalent when dairy production was replaced. Conclusions. The environmental benefits associated with replacing NSW dairy production with plant-based alternatives should not be determined by attributionally-based approaches. Implications. Policies that aim to reduce the environmental impacts of agricultural production need to consider the market effects of a change in demand for products and not rely on estimated impacts of current production.
|
|
| 9. |
|
|
| 10. |
- Simmons, Benno I., et al.
(author)
-
Motifs in bipartite ecological networks: uncovering indirect interactions
- 2019
-
In: Oikos. - : WILEY. - 0030-1299 .- 1600-0706. ; 128:2, s. 154-170
-
Journal article (peer-reviewed)abstract
- Indirect interactions play an essential role in governing population, community and coevolutionary dynamics across a diverse range of ecological communities. Such communities are widely represented as bipartite networks: graphs depicting interactions between two groups of species, such as plants and pollinators or hosts and parasites. For over thirty years, studies have used indices, such as connectance and species degree, to characterise the structure of these networks and the roles of their constituent species. However, compressing a complex network into a single metric necessarily discards large amounts of information about indirect interactions. Given the large literature demonstrating the importance and ubiquity of indirect effects, many studies of network structure are likely missing a substantial piece of the ecological puzzle. Here we use the emerging concept of bipartite motifs to outline a new framework for bipartite networks that incorporates indirect interactions. While this framework is a significant departure from the current way of thinking about bipartite ecological networks, we show that this shift is supported by analyses of simulated and empirical data. We use simulations to show how consideration of indirect interactions can highlight differences missed by the current index paradigm that may be ecologically important. We extend this finding to empirical plant-pollinator communities, showing how two bee species, with similar direct interactions, differ in how specialised their competitors are. These examples underscore the need to not rely solely on network- and species-level indices for characterising the structure of bipartite ecological networks.
|
|
| 11. |
|
|
| 12. |
- Simmons, Christian, et al.
(author)
-
Airborne sound insulation in dwellings - Single numbers weighted from 50-3150 Hz correlated to Swedish questionnaire surveys
- 2019
-
In: Proceedings of the ICA 2019 and EAA Euroregio. - : Deutsche Gesellschaft für Akustik e.V. (DEGA). ; , s. 5063-5070
-
Conference paper (other academic/artistic)abstract
- During the work with the draft standard ISO/DIS 19488 for the sound classification of dwellings, several studies were presented with recommendations on whether 50 or 100 Hz would be the most appropriate lower frequency limit when evaluating single numbers of airborne sound insulation between dwellings. It was observed that 100-3150 Hz is the range used in almost all national building regulations, but including lower frequencies has been considered in some countries and are recommended for higher sound classes in some standards. The Swedish regulations began including evaluation from 50 Hz in 1999, which means there is a long-term experience from the field to support this discussion. In this paper, several single numbers based on field measurements are compared to subjective ratings given by the residents in a variety of building types. The questionnaire surveys were distributed in total 46 building objects with light-weight or heavy walls and floors. Several single number quantities according to ISO 717-1 were correlated against the ratings given by the residents. The statistical evidence for a 50 Hz limit was found to be small on the average, but analysing light-weight buildings separately showed an importance of including sound reduction indices from 50 Hz. Currently, we consider measurements from 50 Hz the best choice when good sound protection against music at low frequencies may occur, since it will also protect from noise at mid and high frequencies. If protection against disturbing speech is sufficient, measuring from 100 Hz is enough. In 2019-2021, about 15 surveys will be made in buildings with timber joist, CLT- or concrete floors.
|
|
| 13. |
- Simmons, Christian, et al.
(author)
-
Aku20 - Searching for Optimal Single Number Quantities in EN ISO 717 Correlating Field Measurements 20-5000 Hz to Occupant's Ratings
- 2015
-
In: Proceedings of EuroNoise 2015. - : European Acoustics Association (EAA). ; , s. 1873-1877
-
Conference paper (peer-reviewed)abstract
- Two versions of a question on impact sounds from neighbouring spaces in dwellings have been demonstrated to return different results. At first, a new version of a questionnaire appeared to be imprecise, too broad etcetera and therefore it returned higher annoyance ratings than the previous, more specific question. But the previous version may have been too restricted - disturbing sounds other than footstep sounds in building with concrete floors seem be a greater problem than anticipated. If so, concrete floors may have appeared to perform better in the previous surveys than occupants actually experience. A modified questionnaire is used in a current survey, which asks for specific sources of impact sounds.
|
|
| 14. |
- Simmons, Christian
(author)
-
Comparison of standard software predictions of the sound insulation in CLT and concrete buildings with field measurements
- 2020
-
In: InterNoise20, Seoul, Korea, pages 990-1987. - : Institute of Noise Control Engineering. ; , s. 1469-1475
-
Conference paper (other academic/artistic)abstract
- Within the research projects AkuLite, Aku20 and the current AkuTimber at LTU, more than 30 newly built wooden buildings have been examined since 2010 by means of detailed field measurements of sound insulations and vibration transmissions. The field results were used to look into a question of practical interest: - When acoustic consultants apply commonly used calculation softwares and their own experience, how close to the real performance is reasonable to assume they will get, on the average? To find out, a selection of building cases examined in the research projects have been studied, amended with a few external measurement results. The first estimates of DnT and LnT were made from the drawings only. The second estimates were supported by the measurement results and vibration transmission measurements to refine the models of the junctions. 30 field measurements of DnT and LnT in buildings with CLT floors as well as 17 measurements in concrete buildings have been compared to calculations made according to EN ISO 12354. The results are presented as average (systematic) deviations and standard deviations, combined to provisional safety margins of 5-8 dB for LnT,w in CLT and 2- 3 dB for concrete buildings respectively.
|
|
