| 1. |
- Hussain, Jawad, et al.
(författare)
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Modeling and simulation of planar SOFC to study the electrochemical properties
- 2020
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Ingår i: Current applied physics. - : ELSEVIER. - 1567-1739 .- 1878-1675. ; 20:5, s. 660-672
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, modeling and simulations are carried out using COMSOL Multiphysics. A three-dimensional model is developed for a planar intermediate temperature (IT) solid oxide fuel cell (SOFC). A parametric study has been carried out to analyze the performance of SOFC. Simulations reveal some promising features and enhanced performance of SOFC. It is shown that the maximum value of power (4-3.3) kW/m(2) still remains higher with significant rise of temperature (600 degrees C-1000 degrees C), nearly 0.15 kW/m(2) is the very small loss of power per 100 degrees C rise of temperature. Results have shown that the electrolytic current density is (6700-5500) A/m(2) for peak value of power (4-3.3) kW/m(2) with increase of temperature (600 degrees C-1000 degrees C). For model validation we have plotted a comparison of average current density.
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| 2. |
- Aldén, Lina, 1979-, et al.
(författare)
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Etnic origin, local labour markets and self-employment in Sweden : A multilevel approach
- 2013
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Ingår i: The annals of regional science. - : Springer Science and Business Media LLC. - 0570-1864 .- 1432-0592. ; 50:3, s. 885-910
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the importance of ethnic origin and local labour markets conditions for self-employment propensities in Sweden. In line with previous research, we find differences in the self-employment rate between different immigrant groups as well as between different immigrant cohorts. We use a multilevel regression approach in order to quantify the role of ethnic background, point of time for immigration and local market conditions in order to further understand differences in self-employment rates between different ethnic groups. We arrive at the following: The self-employment decision is to a major extent guided by factors unobservable in register data. Such factors might be, that is, individual entrepreneurial ability and access to financial capital. The individual’s ethnic background and point of time for immigration play a smaller role for the self-employment decision but are more important than local labour market conditions.
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| 3. |
- Almasri, Abdullah, et al.
(författare)
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Impact of the periodicity and trend on the FD parameter estimation
- 2007
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Ingår i: Journal of Statistical Computation and Simulation. - : Informa UK Limited. - 1563-5163 .- 0094-9655. ; 77:1, s. 79-87
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Tidskriftsartikel (refereegranskat)abstract
- It is well known that one of the features of long-memory processes is that they tend to have what looks like trends and cycles. A consequence of this property is that it is difficult to distinguish a long-memory process from a nonstationary process. In this paper, we study the impact of the periodicity and trend on different methods for estimating the long-memory processes parameter d.
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| 4. |
- Andersson, Lina (current name Aldén, Lina), 1979-, et al.
(författare)
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Ethnic origin, local labour markets and self-employment in Sweden : A multlilevel approach
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- We investigate the importance of ethnic origin and local labour markets conditions for self-employment propensities in Sweden. In line with previous research we find differences in the self-employment rate between different immigrant groups as well as between different immigrant cohorts. We use a multilevel regression approach in order to quantify the role of ethnic background, point of time for immigration and local market conditions in order to further understand differences in self-employment rates between different ethnic groups. We arrive at the following: The self-employment decision is to a major extent guided by factors unobservable in register data. Such factors might be i.e. individual entrepreneurial ability and access to financial capital. The individual’s ethnic background and point of time for immigration play a smaller role for the self-employment decision but are more important than local labour market conditions.
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| 5. |
- Anxo, Dominique, 1953-, et al.
(författare)
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The demand of part-time in European companies : a multilevel modelling approach
- 2012
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Ingår i: Applied Economics. - : Taylor & Francis. - 0003-6846 .- 1466-4283. ; 44:8, s. 1057-1066
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Tidskriftsartikel (refereegranskat)abstract
- Part-time work is one of the most well-known « atypical » working time arrangements. In contrast to previous studies focusing on the supply side, the originality of our research is to investigate the demand-side of part-time work and to examine how and why companies use part-time work. Based on a large and unique sample of European firms operating in 21 member states, we use a multilevel multinomial modeling in a Bayesian environment. Our results suggest that the variations in the extent of part-time workers at the establishment level is determined more by country-specific features than by industry specific factors.
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| 6. |
- Araghi, Marzieh Hosseini, et al.
(författare)
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Effectiveness of Lifestyle Interventions on Obstructive Sleep Apnea (OSA) : Systematic Review and Meta-Analysis
- 2013
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Ingår i: Sleep. - : Oxford University Press. - 0161-8105 .- 1550-9109. ; 36:10, s. 1553-1562
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Forskningsöversikt (refereegranskat)abstract
- Background: Obstructive sleep apnea (OSA) is a common sleep disorder associated with several adverse health outcomes. Given the close association between OSA and obesity, lifestyle and dietary interventions are commonly recommended to patients, but the evidence for their impact on OSA has not been systematically examined. Objectives: To conduct a systematic review and meta-analysis to assess the impact of weight loss through diet and physical activity on measures of OSA: apnea-hypopnea index (AHI) and oxygen desaturation index of 4% (ODI4). Methods: A systematic search was performed to identify publications using Medline (1948-2011 week 40), EMBASE (from 1988-2011 week 40), and CINAHL (from 1982-2011 week 40). The inverse variance method was used to weight studies and the random effects model was used to analyze data. Results: Seven randomized controlled trials (519 participants) showed that weight reduction programs were associated with a decrease in AHI (-6.04 events/h [95% confidence interval -11.18, -0.90]) with substantial heterogeneity between studies (I-2 = 86%). Nine uncontrolled before-after studies (250 participants) showed a significant decrease in AHI (-12.26 events/h [95% confidence interval -18.51, -6.02]). Four uncontrolled before-after studies (97 participants) with ODI4 as outcome also showed a significant decrease in ODI4 (-18.91 episodes/h [95% confidence interval -23.40, -14.43]). Conclusions: Published evidence suggests that weight loss through lifestyle and dietary interventions results in improvements in obstructive sleep apnea parameters, but is insufficient to normalize them. The changes in obstructive sleep apnea parameters could, however, be clinically relevant in some patients by reducing obstructive sleep apnea severity. These promising preliminary results need confirmation through larger randomized studies including more intensive weight loss approaches.
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| 7. |
- Aude, Samar Abdulhameed, et al.
(författare)
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Slope Stability And Soil Liquefaction Analysis Of Earth Dams With A Proposed Method Of Geotextile Reinforcement
- 2022
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Ingår i: International Journal of GEOMATE. - : GEOMATE International Society. - 2186-2982 .- 2186-2990. ; 22:94, s. 102-112
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Tidskriftsartikel (refereegranskat)abstract
- Dam projects require comprehensive studies and a careful implementation process; thus, the causes of the possible failure, during the construction or operation of dams, should be thoroughly investigated. Specifically, geotechnical analysis of seepage, static stability, and seismic stability is essential to be evaluated. Earthquakes shaking imposes additional hysteric and short-term loads in the two directions that may cause serious problems and may lead to dam failure due to settlement, piping, high pore water pressure, and soil liquefaction. In this study, Geo-Studio 2018 software was utilized to evaluate the slope stability and the seepage analysis of Al-Adhaim Dam in Iraq. The dynamic stability of the dam and the soil liquefaction were also evaluated as a result of applying earthquake shaking to the dam. The results obtained from the analysis indicated that the dam was stable in the static condition. Furthermore, the results of the dynamic condition indicated that an earthquake, with an acceleration value of 0.38g and 10 seconds period, caused a vertical displacement of the dam of 0.12 m and reduced the factor of safety to 1.01 which was less than the allowable value. Therefore, geotextile reinforcement was suggested to reduce the effect of the soil liquefaction that was observed in the front shell of the dam. As discussed herein, the reinforcement increased the dam stability as the factor of safety of the dam increased to 1.946 which was within the allowable values.
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| 8. |
- Hussain, Shakir, et al.
(författare)
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Conditional two level mixture with known mixing proportions : applications to school and student level overweight and obesity data from Birmingham, England
- 2014
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Ingår i: International Journal of Statistics in Medical Research. - Mississauga : Lifescience Global. - 1929-6029. ; 3:3, s. 298-308
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Tidskriftsartikel (refereegranskat)abstract
- Two Level (TL) models allow the total variation in the outcome to be decomposed as level one and level two or ‘individual and group’ variance components. Two Level Mixture (TLM) models can be used to explore unobserved heterogeneity that represents different qualitative relationships in the outcome.In this paper, we extend the standard TL model by introducing constraints to guide the TLM algorithm towards a more appropriate data partitioning. Our constraints-based methods combine the mixing proportions estimated by parametric Expectation Maximization (EM) of the outcome and the random component from the TL model. This forms new two level mixing conditional (TLMc) approach by means of prior information. The new framework advantages are: 1. avoiding trial and error tactic used by TLM for choosing the best BIC (Bayesian Information Criterion), 2. permitting meaningful parameter estimates for distinct classes in the coefficient space and finally 3. allowing smaller residual variances. We show the benefit of our method using overweight and obesity from Body Mass Index (BMI) for students in year 6. We apply these methods on hierarchical BMI data to estimate student multiple deprivation and school Club effects.
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| 9. |
- Hussain, Shakir, et al.
(författare)
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Congenial Multiple Imputation and Matched Pairs Models for Square Tables : An Example of patients’ self-management
- 2013
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Ingår i: Journal of Business Administration Research. - : Sciedu Press. - 1927-9507 .- 1927-9515. ; 2:1, s. Article ID: 1-
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Tidskriftsartikel (refereegranskat)abstract
- Experimental studies often measure an individual’s quality of life before and after an intervention, with the data organized into a square table and analyzed using matched pair modeling. However, it is not unusual to find missing data in either round (i.e., before and/or after) of such studies and the use of multiple imputations with matched-pair modeling remains relatively unreported in the applied statistics literature. In this paper we introduce an approach which maintains dependency of responses over time and makes a match between the imputer and the analyst. We use ‘before’ and ‘after’ quality-of-life data from a randomized controlled trial to demonstrate how multiple imputation and matched-pair modeling can be congenially combined, avoiding a possible mismatch of imputation and analyses, and to derive a properly consolidated analysis of the quality-of-life data. We illustrate this strategy with a real-life example of one item from a quality-of-life study that evaluates the effectiveness of patients’ self-management of anticoagulation versus standard care as part of a randomized controlled trial.
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| 10. |
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