| 1. |
- Baratieri, Marco, et al.
(författare)
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Biomass Gasification with Dolomite as Catalyst in a Small Fluidized Bed Experimental and Modelling Analysis
- 2010
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Ingår i: Waste and Biomass Valorization. - : Springer Science+Business Media B.V.. - 1877-2641 .- 1877-265X. ; 1:3, s. 283-291
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Tidskriftsartikel (refereegranskat)abstract
- Purpose Actually, one of the main challenges to be achieved in biomass gasification is the minimization of tar concentration in combination with optimization of the gas composition. An extensive examination has been performed in order to expose the effect of several Chinese dolomites as a catalyst for tar cracking and gas composition enhancement. In this paper, the experimental data collected are presented. Methods Thebiomass gasification tests have been performed in a laboratory small-scale atmosphericfluidized bed gasifier that uses nitrogen as a fluidizing media and pure oxygen as gasifying agent. The system is equipped with a ceramic filter and a catalytic bed. Different types of dolomites have been used as catalyst. Results The main results are that thedolomite reduces the tar concentration and at the same time increases the permanent gas yield. A gasification equilibrium model, written in Matlab environment, has been developed to predict the synthesis gas composition. Main conclusions Several biomassgasification tests have been performed to assess the dolomite effect on the syngas and tar composition. The results have been used to tune an equilibrium model up. The model has been modified with some experimental data and it seems to predict with good accuracy the syngas composition.
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| 2. |
- Haug, Thomas, et al.
(författare)
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Self-help treatment of anxiety disorders : A meta-analysis and meta-regression of effects and potential moderators
- 2012
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Ingår i: Clinical Psychology Review. - : Elsevier BV. - 0272-7358 .- 1873-7811. ; 32:5, s. 425-445
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Forskningsöversikt (refereegranskat)abstract
- Self-help treatments have the potential to increase the availability and affordability of evidence-based treatments for anxiety disorders. Although promising, previous research results are heterogeneous, indicating a need to identify factors that moderate treatment outcome. The present article reviews the literature on self-help treatment for anxiety disorders among adults, with a total sample of 56 articles with 82 comparisons. When self-help treatment was compared to wait-list or placebo, a meta-analysis indicated a moderate to large effect size (g = 0.78). When self-help treatment was compared to face-to-face treatment, results indicated a small effect that favored the latter (g = -0.20). When self-help was compared to wait-list or placebo, subgroup analyses indicated that self-help treatment format, primary anxiety diagnosis and procedures for recruitment of subjects were related to treatment outcome in bivariate analyses, but only recruitment procedures remained significant in a multiple meta-regression analysis. When self-help was compared to face-to-face treatment, a multiple meta-regression indicated that the type of comparison group, treatment format and gender were significantly related to outcome. We conclude that self-help is effective in the treatment of anxiety disorders, and should be offered as part of stepped care treatment models in community services. Implications of the results and future directions are discussed.
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| 3. |
- Haug, Thomas, et al.
(författare)
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Stepped care versus face-to–face cognitive behavior therapy for panic disorder and social anxiety disorder : Predictors and moderators of outcome
- 2015
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Ingår i: Behaviour Research and Therapy. - : Elsevier. - 0005-7967 .- 1873-622X. ; 71, s. 76-89
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To investigate predictors and moderators of treatment outcome by comparing immediate face-to-face cognitive behavioral therapy (FtF-CBT) to a Stepped Care treatment model comprising three steps: Psychoeducation, Internet-delivered CBT, and FtF-CBT for panic disorder (PD) and social anxiety disorder (SAD).Method: Patients (N = 173) were recruited from nine public mental health out-patient clinics and randomized to immediate FtF-CBT or Stepped Care treatment. Characteristics related to social functioning, impairment from the anxiety disorder, and comorbidity was investigated as predictors and moderators by treatment format and diagnosis in multiple regression analyses.Results: Lower social functioning, higher impairment from the anxiety disorder, and a comorbidcluster C personality disorder were associated with significantly less improvement, particularly among patients with PD. Furthermore, having a comorbid anxiety disorder was associated with a better treatment outcome among patients with PD but not patients with SAD. Patients with a comorbid depression had similar outcomes from the different treatments, but patients without comorbid depression had better outcomes from immediate FtF-CBT compared to guided self-help.Conclusions: In general, the same patient characteristics appear to be associated with the treatment outcome for CBT provided in low- and high-intensity formats when treated in public mental health care clinics. The findings suggest that patients with lower social functioning and higher impairment from their anxiety disorder benefit less from these treatments and may require more adapted and extensive treatment.ClinicalTrials.govIdentifier: NCT00619138.
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| 4. |
- Haug, Thomas, et al.
(författare)
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Working alliance and competence as predictors of outcome in cognitive behavioral therapy for social anxiety and panic disorder in adults
- 2016
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Ingår i: Behaviour Research and Therapy. - : Elsevier BV. - 0005-7967 .- 1873-622X. ; 77, s. 40-51
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The research on the association between the working alliance and therapist competence/adherence and outcome from cognitive behavioral therapy (CBT) is limited and characterized by inconclusive findings. This study investigates the working alliance and competence/adherence as predictors of outcome of CBT for social anxiety disorder(SAD) and panic disorder (PD).Method: Eighty-two clinically referred patients (58.5% female; age: M = 33.6 years, SD = 10.3) with PD (n = 31) or SAD (n = 51) were treated with 12 sessions of manualized CBT by 22 clinicians with limited CBT experience in a randomized controlled effectiveness trial. Independent assessors rated the CBT competence/adherence of the therapists using a revised version of the Cognitive Therapy Adherence and Competence Scale, and the patients rated the quality of the working alliance using the Working Alliance Inventory-short form in therapy sessions 3 and 8. The outcome was assessed by independent assessors as well as by patients self-report. A total of 20.7% of the patients (27.5% SAD, 9.7% PD) dropped out during treatment. The association between the alliance, competence/adherence, outcome and dropout was investigated using multiple regression analyses.Results: Higher therapist' competence/adherence early in the therapy was associated with a better outcome among PD patients, lower competence/adherence was associated with dropout among SAD patients. Higher rating of the alliance late in the therapy was associated with a better outcome, whereas lower alliance rating late in the therapy was associated with dropout.Conclusion: The findings indicate that the therapist competence/adherence and the working alliance have independent contributions to the outcome from CBT for anxiety disorders, but in different phases of the treatment.
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| 5. |
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| 6. |
- Nemanova, Vera, et al.
(författare)
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Biomass gasification in an atmospheric fluidised bed : Tar reduction with experimental iron-based granules from Höganäs AB, Sweden
- 2011
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Ingår i: Catalysis Today. - : Elsevier BV. - 0920-5861 .- 1873-4308. ; 176:1, s. 253-257
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Tidskriftsartikel (refereegranskat)abstract
- The present study investigates the effect of several experimental iron-based granules on biomass tar decomposition. The iron-based materials were provided by Höganäs AB and were all in their metallic state when they were applied in a secondary catalytic reactor. Bark-free birch was employed as fuel in an atmospheric fluidised bed reactor, and the tar concentration and gas composition in the producer gas were measured before and after the catalytic bed. The results demonstrate a clear tar reduction capacity for all the tested iron-based materials.
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| 7. |
- Nordgreen, Thomas, et al.
(författare)
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Elemental iron as a tar breakdown catalyst in conjunction with atmospheric fluidized bed gasification of biomass : A thermodynamic study
- 2006
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 20:3, s. 890-895
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Tidskriftsartikel (refereegranskat)abstract
- Metallic iron as a catalyst for tar cracking in biomass gasification has been investigated. Based on previous studies showing that iron must be in its elemental form to catalyze the tar breakdown reactions, thermodynamic calculations suggest the existence of an operating window where iron is neither oxidized nor contaminated by carbon deposits. A straightforward biomass gasification model has been derived and used in conjunction with thermodynamics for making plots that illustrate the mentioned operating window, which is achievable under real conditions. Experiments made under these specific calculated conditions confirm that elemental iron effectively acts as a tar breakdown catalyst, resulting in an improved gas yield and a decrease in tar concentration. The desired operating window is governed mainly by adjusting the oxygen input (i.e., the equivalence ratio) and the temperature.
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| 8. |
- Nordgreen, Thomas
(författare)
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Iron-based materials as tar cracking catalyst in waste gasification
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The treatment of municipal solid waste (MSW) in Sweden has changed during the past decades due to national legislation and European Union directives. The former landfills have more or less been abandoned in favour of material recycling and waste incineration. On a yearly basis approximately 2.2 million tonnes waste are incinerated in Sweden with heat recovery and to some extent also with electricity generation, though at a low efficiency. It is desirable to alter this utilisation and instead employ MSW as fuel in a fluid bed gasification process. Then electrical energy may be produced at a much higher efficiency. However, MSW contain about 1 % chlorine in the form of ordinary table salt (NaCl) from food scraps. This implies that the tar cracking catalyst, dolomite, which is normally employed in gasification, will suffer from poisoning if applied under such conditions. Then the tar cracking capacity will be reduced or vanish completely with time. Consequently, an alternative catalyst, more resistant to chlorine, is needed. Preliminary research at KTH has indicated that iron in its metallic state may possess tar cracking ability. With this information at hand and participating in the project “Energy from Waste” an experimental campaign was launched. Numerous experiments were conducted using iron as tar cracking catalyst. First iron sinter pellets from LKAB were employed. They were reduced in situ with a stream of hydrogen before they were applied. Later iron-based granules from Höganäs AB were tested. These materials were delivered in the metallic state. In all tests the KTH atmospheric fluidised bed gasifier with a secondary catalytic reactor housing the catalytic material was deployed. Mostly, the applied fuel was birch. The results show that metallic iron possesses an intrinsic ability, almost in the range of dolomite, to crack tars. Calculations indicate that iron may be more resistant to chlorine than dolomite. The exploration of metallic iron’s excellent tar cracking capacity led to the innovative manufacture of an iron catalytic tar cracking filter as well as a general knowledge of its tar cracking capacity. This filter with dual functionality would be a general improvement of the gasification process since it among other things would make the process denser.
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| 9. |
- Nordgreen, Thomas, et al.
(författare)
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Iron-based materials as tar depletion catalysts in biomass gasification : Dependency on oxygen potential
- 2012
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 95:1, s. 71-78
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Tidskriftsartikel (refereegranskat)abstract
- A study has been performed using experimental iron based granules as a tar breakdown catalyst in a biomass gasification gas. Previous examinations established that metallic iron located in a separate catalytic bed reactor has a stronger influence on the tar content and composition in the product gas than their corresponding iron oxides. The results from the present study show that tar diminution in the product gas is dependent on temperature, catalyst material and oxygen potential. Typically, values of 50-75% tar reduction were achieved when varying the catalytic bed temperature between 750 and 850 degrees C. Also, the oxidation state of the catalyst material has an influence on the tar content and gas composition in the gas. When changing the gasification temperature from 800 degrees C to 850 degrees C the oxygen potential in the producer gas also changes, resulting in a transition from oxidative to reductive conditions in the gas. This implies that when the gasification temperature is 800 degrees C, the catalyst is transformed from its metallic state to the iron oxide, wustite. Consequently, the tar reduction capacity of the catalyst is reduced by approximately 20%. In view of the overall results it can be concluded that the catalysts in their metallic states in general exhibits a better tar cracking capacity than their corresponding oxides. The iron material used is sintered iron powders manufactured at Hoganas AB, Sweden. The iron materials were dispensed in the metallic state.
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| 10. |
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| 11. |
- Nordgreen, Thomas, et al.
(författare)
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Metallic iron as a tar breakdown catalyst related to atmospheric, fluidised bed gasification of biomass
- 2006
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 85:06-maj, s. 689-694
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Tidskriftsartikel (refereegranskat)abstract
- Tar formation is a major drawback when biomass is converted in a gasifier to obtain gas aimed for utilisation in power production plants or for production of chemicals. Catalytic cracking is an efficient method to diminish the tar content in the gas mixture. In this study, the capability of metallic iron and iron oxides to catalytically crack tars has been experimentally examined. To obtain metallic iron, small grains of hematite (Fe2O3) were placed in a secondary reactor downstream the gasifier and reduced in situ prior to catalytic operation. The fuel used in the atmospheric fluidised bed gasifier was Swedish birch with a moisture content of approximately 7 wt%. The influence of temperature in the range 700-900 degrees C and), values (i.e. equivalence ratio, ER) between 0 and 0.20 have been investigated. In essence, the results show that raising the temperature in the catalytic bed to approximately 900 degrees C yields almost 100% tar breakdown. Moreover, increasing the). value also improves the overall tar cracking activity. The iron oxides did not demonstrate any catalytic activity.
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| 12. |
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| 13. |
- Nordgreen, Tine, et al.
(författare)
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Stepped Care Versus Direct Face-to-Face Cognitive Behavior Therapy for Social Anxiety Disorder and Panic Disorder : A Randomized Effectiveness Trial
- 2016
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Ingår i: Behavior Therapy. - : Elsevier BV. - 0005-7894 .- 1878-1888. ; 47:2, s. 166-183
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to assess the effectiveness of a cognitive behavioral therapy(CBT) stepped care model (psychoeducation, guided Internet treatment, and face-to-face CBT) compared with direct face-to-face (FtF) CBT. Patients with panic disorder or social anxiety disorder were randomized to either stepped care (n = 85) or direct FtF CBT (n = 88). Recovery was defined as meeting two of the following three criteria: loss of diagnosis, below cut-off for self-reported symptoms, and functional improvement. No significant differences in intention-to-treat recovery rates were identified between stepped care (40.0%) and direct FtF CBT (43.2%). The majority of the patients who recovered in the stepped care did so at the less therapist-demanding steps (26/34, 76.5%). Moderate to large within-groups effect sizes were identified at posttreatment and 1-year follow-up. The attrition rates were high: 41.2% in the stepped care condition and 27.3% in the direct FtF CBT condition. These findings indicate that the outcome of a stepped care model for anxiety disorders is comparable to that of direct FtF CBT. The rates of improvement at the two less therapist-demanding steps indicate that stepped care models might be useful for increasing patients’ access to evidence-based psychological treatments for anxiety disorders. However, attrition in the stepped care condition was high, and research regarding the factors that can improve adherence should be prioritized.
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| 14. |
- Smoktunowicz, Ewelina, et al.
(författare)
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Consensus statement on the problem of terminology in psychological interventions using the internet or digital components
- 2020
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Ingår i: Internet Interventions. - : Elsevier. - 2214-7829. ; 21, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- Since the emergence of psychological interventions delivered via the Internet they have differed in numerous ways. The wealth of formats, methods, and technological solutions has led to increased availability and cost-effectiveness of clinical care, however, it has simultaneously generated a multitude of terms. With this paper, we first aim to establish whether a terminology issue exists in the field of Internet-delivered psychological interventions. If so, we aim to determine its implications for research, education, and practice. Furthermore, we intend to discuss solutions to mitigate the problem; in particular, we propose the concept of a common glossary. We invited 23 experts in the field of Internet-delivered interventions to respond to four questions, and employed the Delphi method to facilitate a discussion. We found that experts overwhelmingly agreed that there were terminological challenges, and that it had significant consequences for conducting research, treating patients, educating students, and informing the general public about Internet-delivered interventions. A cautious agreement has been reached that formulating a common glossary would be beneficial for the field to address the terminology issue. We end with recommendations for the possible formats of the glossary and means to disseminate it in a way that maximizes the probability of broad acceptance for a variety of stakeholders.
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| 15. |
- Valderrama, Cesar, et al.
(författare)
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Shared curriculum at KTH and UPC universities Blended learning experience at the MSc SELECT programme
- 2018
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Ingår i: PROCEEDINGS OF 2018 IEEE GLOBAL ENGINEERING EDUCATION CONFERENCE (EDUCON) - EMERGING TRENDS AND CHALLENGES OF ENGINEERING EDUCATION. - : IEEE. - 9781538629574 ; , s. 669-676
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Konferensbidrag (refereegranskat)abstract
- The aim of this paper is to present the experience and lessons learned of experimental implementing of blended learning methodology in the Master programme "Environomical Pathways for Sustainable Energy Systems" (SELECT) at the Royal Institute of Technology' (KTH in Stockholm) and the Universitat Politecnica de Catalunya.BarcelonaTech (UPC in Barcelona), in common and remotely taught courses (shared curriculum) under a transnational framework. Shared curriculum has been designed and strongly connected to the intended learning outcomes (ILO's) of the programme. Blended learning was implemented to improve the efficiency of the learning process through updated technological means of instruction and to have the same curriculum with equally shared teaching load to ensure that students by the end of year I have the same competence and background. It can be noted that, at least from the perspective of academic performance, the implementation of blended learning in the shared SELECT curriculum does not have a significant impact, although local students show slightly higher grade point average (GPA). Finally and from our general experience with students, it is possible to identify the interaction of communication as one of the key challenges and factors in blended education.
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| 16. |
- Yu, Q. Z., et al.
(författare)
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Effects of Chinese dolomites on tar cracking in gasification of birch
- 2009
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 88:10, s. 1922-1926
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Tidskriftsartikel (refereegranskat)abstract
- To minimize tar in the producer gas from birch gasification at 700, 750 and 800 degrees C, four Chinese dolomites (Zhenjiang, Nanjing, Shanxi, Anhui) and a Swedish dolomite (Sala) used as reference were studied in a laboratory-scale atmospheric fluidized bed gasifier. The gasifier was equipped with a downstream fixed catalyst bed. The results imply that all dolomites but Anhui dolomite effectively decompose tar into gases. Anhui dolomite showed a low catalytic capacity to crack tar produced at 700 and 800 degrees C. The influence of various ratios of steam to biomass on tar content in the producer gas after passing over dolomite was studied. The tar cracking efficiency of the dolomites did not improve significantly with the ratio of steam to biomass in the region 0.11-0.52.
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