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- Jeppsson, Ulf, et al.
(författare)
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Benchmark simulation model no 2: general protocol and exploratory case studies
- 2007
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Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 56:8, s. 67-78
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Tidskriftsartikel (refereegranskat)abstract
- Over a decade ago, the concept of objectively evaluating the performance of control strategies by simulating them using a standard model implementation was introduced for activated sludge wastewater treatment plants. The resulting Benchmark Simulation Model No 1 (BSM1) has been the basis for a significant new development that is reported on here: Rather than only evaluating control strategies at the level of the activated sludge unit (bioreactors and secondary clarifier) the new BSM2 now allows the evaluation of control strategies at the level of the whole plant, including primary clarifier and sludge treatment with anaerobic sludge digestion. In this contribution, the decisions that have been made over the past three years regarding the models used within the BSM2 are presented and argued, with particular emphasis on the ADM1 description of the digester, the interfaces between activated sludge and digester models, the included temperature dependencies and the reject water storage. BSM2-implementations are now available in a wide range of simulation platforms and a ring test has verified their proper implementation, consistent with the BSM2 definition. This guarantees that users can focus on the control strategy evaluation rather than on modelling issues. Finally, for illustration, twelve simple operational strategies have been implemented in BSM2 and their performance evaluated. Results show that it is an interesting control engineering challenge to further improve the performance of the BSM2 plant (which is the whole idea behind benchmarking) and that integrated control (i.e. acting at different places in the whole plant) is certainly worthwhile to achieve overall improvement.
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- Nawka, T, et al.
(författare)
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Item reduction of the voice handicap index based on the original version and on European translations
- 2009
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Ingår i: Folia phoniatrica et logopaedica : official organ of the International Association of Logopedics and Phoniatrics (IALP). - : S. Karger AG. - 1421-9972. ; 61:1, s. 37-48
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Tidskriftsartikel (refereegranskat)abstract
- <i>Objective:</i> Constructing an internationally applicable short-scale of the Voice Handicap Index (VHI). <i>Methods:</i> Subjects were 1,052 patients with 5 different types of voice disorder groups from Belgium, France, Sweden, Germany, Italy, The Netherlands, Portugal, and the USA. Different 9- and 12-item subsets were selected from the 30 VHI items using (1) the first factor of an unrotated factor analysis (narrow range subsets) and (2) the first three factors after promax rotation (broad range subsets). Country-specific subsets were selected to test deviations from the international subsets. For all subsets, reliability was investigated using Cronbach’s alphas and correlations with the total VHI. Validity was investigated using regression on voice disorder groups. All analyses were performed for the total and for all country-specific subject samples. <i>Results:</i> Reliability was high for all item subsets. It was lower for the international compared to the country-specific subsets and for the broad range compared to the narrow range subsets. Validity was best for the broad range subsets. Validity was better for the international than for the country-specific subsets. For all statistics the 12-item subsets were not essentially better than the 9-item subsets. <i>Conclusion:</i> The international broad range 9-item subset forms a scale which approximates well the total VHI.
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- Sunesson, A-L, et al.
(författare)
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Multivariate evaluation of VOCs in buildings where people with non-specific building-related symptoms perceive health problems and in buildings where they do not.
- 2006
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Ingår i: Indoor Air. - : Hindawi Limited. - 0905-6947 .- 1600-0668. ; 16:5, s. 383-391
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Tidskriftsartikel (refereegranskat)abstract
- Volatile organic compounds (VOCs) were sampled in buildings where people with non-specific building-related symptoms perceive health problems and in buildings where they do not. In total, nine persons and 34 buildings were included in the study. The obtained VOC data was evaluated using multivariate methods, to investigate possible systematic differences in air quality of 'problem' and 'non-problem' buildings. All individual compounds were included as variables in a multivariate partial least squares (PLS) data analysis. 'Problem' and 'non-problem' buildings separated into two distinct groups, showing that air samples of the two groups of building were chemically different. PRACTICAL IMPLICATIONS: The study showed that there was an identifiable systematic difference in the collected VOC data between buildings causing and not causing problems for people with non-specific building-related symptoms (also called sick building syndrome, SBS). This is an important indication that even such volatile organic compounds that can be sampled by commonly used adsorbents are of importance for the presence of such symptoms. By coordination of procedures for sampling and analysis of VOCs in buildings between laboratories, to get large datasets and more general models, the method can become a useful diagnostic measure in evaluating indoor air and to identify chemical compounds and sources that contribute to SBS problems.
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