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CFB cyclones at high temperature:Operational results and design assessment

Particuology 2008年第3期6卷 149-156页

作者： raf Dewil Jan Baeyens Bart Caerts Department of Chemical Engineering Associated Faculty of Technology and Bio-sciencesCampus De NayerKatholieke Universiteit LeuvenJan De Nayerlaan 5B-2860 Sint-Katelijne-WaverBelgium Department of Chemical Engineering University of BirminghamEdgbastonBirmingham B15 2TTUnited Kingdom Department of Chemical Engineering Katholieke Universiteit LeuvenWillem De Croylaan 46B-3001 HeverleeBelgium

Pressure drop and cut size measurements are reported for a full scale cyclone operating within a 58 mWth CFB-combustor unit at 775 ℃. The paper reviews the vast number of equations to calculate the pressure drop and separation efficiency of cyclones, generally for operation at ambient temperature and at low Cs [〈0.5]. None of the literature correlations predicts the pressure drop with a fair accuracy within the range of experimental operating conditions. The cut size d50 can be estimated using direct empirical methods or using the Stokes number, Stk50. Both methods were used to compare measured and predicted values of d50. With the exception of muschelknautz and Krambrock, none of the equations made accurate predictions. Finally, an alternative method to determine the friction factor of the pressure drop equation （Euler number, Eu） and of the cut size is proposed. The Eu number is determined from the geometry of common cyclones, and the derived value of Stk50 defines more accurate cut sizes. The remaining discrepancy of less than 5%, when compared with the measured values, is tentatively explained in terms of a reduced cyclone diameter due to the solids layer formed near its wall. Further measurements, mostly using positron emission particle tracking, elucidate the particle motion in the cyclone and both tracking results and the influence of the particle movement on Eu and Stk50 will be discussed in a follow-up paper.

关键词： Cyclone High loading High temperature Combustor

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Predictive Characteristics of Co-authorship Networks: Comparing the unweighted, Weighted, and Bipartite Cases

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Journal of Data and Information Science 2016年第3期1卷 59-78页

作者： raf Guns Centre for R&D monitoring (ECOOm) University of Antwerp

Purpose： This study aims to answer the question to what extent different types of networks can be used to predict future co-authorship among ***/methodology/approach： We compare three types ot networks： unwelgntea networks, in which a link represents a past collaboration; weighted networks, in which links are weighted by the number of joint publications; and bipartite author-publication networks. The analysis investigates their relation to positive stability, as well as their potential in predicting links in future versions of the co-authorship network. Several hypotheses are ***： Among other results, we find that weighted networks do not automatically lead to better predictions. Bipartite networks, however, outperform unweighted networks in almost all cases. Research limitations： Only two relatively small case studies are considered Practical implications： The study suggests that future link prediction studies on networks should consider using the bipartite network as a training network. Originality/value： This is the first systematic comparison of unweighted, weighted, and bipartite training networks in link prediction.

关键词： Network evolution Link prediction Weighted networks Bipartite networks Two-mode networks

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Recent advances in H_(2)O_(2)-based advanced oxidation processes for removal of antibiotics from wastewater

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Chinese Chemical Letters 2023年第3期34卷 39-48页

作者： Xuechun Wang Jiana Jing minghua Zhou raf Dewil Key Laboratory of Pollution Process and Environmental Criteria Ministry of EducationCollege of Environmental Science and EngineeringNankai UniversityTianjin 300350China Tianjin Key Laboratory of Environmental Technology for Complex Trans-media Pollution Nankai UniversityTianjin 300350China Tianjin Advanced Water Treatment Technology International Joint Research Center College of Environmental Science and EngineeringNankai UniversityTianjin 300350China Department of Chemical Engineering KU LeuvenJ.De Nayerlaan 5Sint-Katelijne-Waver B-2860Belgium

As important emerging contaminants, antibiotics have caused potential hazards to the ecological environment and human health due to their extensive production and consumption. Among various techniques for removing antibiotics from wastewater, H_(2)O_(2)-based advanced oxidation processes(AOPs) have received increasing attention due to their fast reaction rate and strong oxidation capability. Hence this review critically discusses:(i) Recent research progress of AOPs with the addition of H_(2)O_(2) for antibiotics removal through different methods of H_(2)O_(2) activation;(ii) recent advances in AOPs that can in-situ generate and activate H_(2)O_(2) for antibiotics removal;(iii) H_(2)O_(2)-based AOPs as a combination with other techniques for the degradation and mineralization of antibiotics in wastewater. Future perspectives about H_(2)O_(2)-based AOPs are also presented to grasp the future research trend in the area.

关键词： Advanced oxidation processes H_(2)O_(2)in-situ generation Antibiotics degradation Combined AOPs Wastewater treatment

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The Flemish Performance-based Research Funding System: A unique Variant of the Norwegian model

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Journal of Data and Information Science 2018年第4期3卷 45-60页

作者： Tim C.E.Engels raf Guns Centre for R&D monitoring (ECOOm) Faculty of Social Science University of Antwerp

The BOF-key is the performance-based research funding system that is used in Flanders, Belgium. In this paper we describe the historical background of the system, its current design and organization, as well as its effects on the Flemish higher education landscape. The BOFkey in its current form relies on three bibliometric parameters: publications in Web of Science, citations in Web of Science, and publications in a comprehensive regional database for SSH publications. Taken together, the BOF-key forms a unique variant of the Norwegian model: while the system to a large extent relies on a commercial database, it avoids the problem of inadequate coverage of the SSH. Because the bibliometric parameters of the BOF-key are reused in other funding allocation schemes, their overall importance to the Flemish universities is substantial.

关键词： Performance-based research funding systems Flanders(Belgium) Norwegian model Web of Science VABB-SHW

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Patterns of forest composition and their long term environmental drivers in the tropical dry forest transition zone of southern Africa

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Forest Ecosystems 2017年第1期4卷 33-44页

作者： Vera De Cauwer Coert J.Geldenhuys raf Aerts miya Kabajani Bart muys Namibia university of Science and Technology Faculty of Natural Resources and Spatial SciencesPrivate Bag 13388WindhoekNamibia university of Leuven Division ForestNature and LandscapeCelestijnenlaan 200E box 2411BE-3001 LeuvenBelgium. Forest&Wood Science Stellenbosch Universityc/o Forestwood ccMurrayfieldPretoriaSouth Africa. university of Leuven Division EcologyEvolution and Biodiversity ConservationKasteelpark Arenberg 31-2435BE-3001 LeuvenBelgium.

Background： Tropical dry forests cover less than 13 % of the world＇s tropical forests and their area and biodiversity are declining. In southern Africa, the major threat is increasing population pressure, while drought caused by climate change is a potential threat in the drier transition zones to shrub land. monitoring climate change impacts in these transition zones is difficult as there is inadequate information on forest composition to allow disentanglement from other environmental drivers. methods： This study combined historical and modern forest inventories covering an area of 21,000 km2 in a transition zone in Namibia and Angola to distinguish late succession tree communities, to understand their dependence on site factors, and to detect trends in the forest composition over the last 40 years. Results： The woodlands were dominated by six tree species that represented 84 % of the total basal area and can be referred to as Bdikioea - Pterocarpus woodlands. A boosted regression tree analysis revealed that late succession tree communities are primarily determined by climate and topography. The Schinziophyton rautanenfi and Baikiaea plurijuga communities are common on slightly inclined dune or valley slopes and had the highest basal area （5.5 - 6.2 m^2 ha＆-1）. The Burkea africana - Guibourtia coleosperma and Pterocarpus angolensis - Diafium englerianum communities are typical for the sandy plateaux and have a higher proportion of smaller stems caused by a higher fire frequency. A decrease in overall basal area or a trend of increasing domination by the more drought and cold resilient B. africana community was not confirmed by the historical data, but there were significant decreases in basal area for Ochna pulchra and the valuable fruit tree D. englerianum. Conclusions： The slope communities are more sheltered from fire, frost and drought but are more susceptible to human expansion. The community with the important timber tree P. angolensis can best withstand high

关键词： Baikiaea woodland Tree community Namibia boosted regression trees Pterocarpus ango/ensis Disturbance miombo Ecoregion Climate change

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unnormalized and normalized forms of gefura measures in directed and undirected networks

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Frontiers of Information Technology & Electronic Engineering 2015年第4期16卷 311-320页

作者： raf GuNS Ronald ROuSSEAu Institute for Education and lnformation Sciences University of Antwerp Venusstraat 35 Antwerp B-2000 Belgium Department of mathematics KU Leuven Celestijnenlaan 200B Leuven B-3001 Belgium

In some networks nodes belong to predefined groups （e.g., authors belong to institutions）. Common network cen- trality measures do not take this structure into account. Gefura measures are designed as indicators of a node＇s brokerage role between such groups. They are defined as variants of betweeuness centrality and consider to what extent a node belongs to shortest paths between nodes from different groups. In this article we make the following new contributions to their study：（1） We systematically study unnormalized gefura measures and show that, next to the ＇structural＇ normalization that has hitherto been applied, a ＇basic＇ normalization procedure is possible. While the former normalizes at the level of groups, the latter normalizes at the level of nodes. （2） Treating undirected networks as equivalent to symmetric directed networks, we expand the definition of gefura measures to the directed case. （3） It is shown how Brandes＇ algorithm for betweenness centrality can be adjusted to cover these cases.

关键词： Networks subdivided in groups Partitions Gefura measures Q-measures Brokerage role Directed and undirectednetworks Brandes' algorithm

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The use of ultrasonics in the Treatment of Waste Activated Sludge

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Chinese Journal of Chemical Engineering 2006年第1期14卷 105-113页

作者： raf Dewil Jan Baeyensa Rebecca Goutvrind university of Antwerp Department of Bio-engineering Groenenborgerlaan 171 B-2020 Antwerp Belgium university of Birmingham Department of Chemical Engineering Edgbaston Birmingham UK SGS Environmental Services Keetberglaan Haven 1091 B-9120 Melsele Belgium

The present paper reports on extensive investigations using an ultrasomc treatment ot WAS, to study its potential to meet one or all of four objectives：（1） reduce WAS quantities; （2） achieve a better dewaterability; （3） provoke a release of COD from the biosolids, preferably transformed into biodegradable organics and （4） possibly destroy the filamentous micro-organisms responsible for sludge bulking. The experiments are carried out in a batch reactor of volume up to 2.3L. The ultrasonic apparatus consisted of a generator, a converter and a sonotrode, supplied by Alpha ultrasonics under the brand name of Telsonic. Three different sludge kinds were tested, at approximate concentration （DS/WAS） between 3.5 and 20g·L^-1. The release of COD from the WAS-phase into the filtrate phase is a function of the specific energy-input SE with yields of about 30% achievable at SE-values of 30000 kJ·kg^-1. A major fraction of the COD is transformed into biodegradable organics （BOD）. The reduction of DS-fraction of the sludge is equivalent to the COD-release rates. Although the dry solids content （DS） is reduced, the dewaterability of the sludge is not improved. This reflects itself in a slightly decreased dryness of the filter cake using vacuum filtration, and in increased values of the capillary suction time （CST）. This more difficult dewaterability is the result of considerably reduced floc sizes, offering an extended surface area. more surface water is bound （CST increases） and the filterability decreases due to clogging of the cake. To reach the same dryness as the untreated cake, the required dosage of poly-electrolyte increases proportionally with the level of ultrasound energy supplied. The ultrasonic reduction of filamentous WAS organisms is not conclusive and very little effect is seen at low intensities and short treatment durations. microscopic analysis of the WAS identified the dominant presence of Actynomyces. Especially the release of COD and its transformation into

关键词： sludge treatment ultrasound dewaterability COD-release bulking

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National Lists of Scholarly Publication Channels: An Overview and Recommendations for Their Construction and maintenance

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Journal of Data and Information Science 2021年第1期6卷 50-86页

作者： Janne Pölönen raf Guns Emanuel Kulczycki Gunnar Sivertsen Tim C.E.Engels Federation of Finnish Learned Societies Snellmaninkatu 1300170 HelsinkiFinland university of Antwerp Faculty of Social SciencesCentre for R&D Monitoring(ECOOM)Middelheimlaan 12020 AntwerpBelgium Adam mickiewicz university Scholarly Communication Research GroupSzamarzewskiego 89c60-568 PoznańPoland Nordic Institute for Studies in Innovation Research and Education(NIFU)P.O.Box 28150608 TøyenOsloNorway

Purpose: This paper presents an overview of different kinds of lists of scholarly publication channels and of experiences related to the construction and maintenance of national lists supporting performance-based research funding systems. It also contributes with a set of recommendations for the construction and maintenance of national lists of journals and book ***/methodology/approach: The study is based on analysis of previously published studies, policy papers, and reported experiences related to the construction and use of lists of scholarly publication channels. Findings: Several countries have systems for research funding and/or evaluation, that involve the use of national lists of scholarly publication channels(mainly journals and publishers). Typically, such lists are selective(do not include all scholarly or non-scholarly channels) and differentiated(distinguish between channels of different levels and quality). At the same time, most lists are embedded in a system that encompasses multiple or all disciplines. This raises the question how such lists can be organized and maintained to ensure that all relevant disciplines and all types of research are adequately represented. Research limitation: The conclusions and recommendations of the study are based on the authors' interpretation of a complex and sometimes controversial process with many different stakeholders *** implications: The recommendations and the related background information provided in this paper enable mutual learning that may feed into improvements in the construction and maintenance of national and other lists of scholarly publication channels in any geographical context. This may foster a development of responsible evaluation ***/value: This paper presents the first general overview and typology of different kinds of publication channel lists, provides insights on expert-based versus metrics-based evaluation, and formulates a set of recommend

关键词： Publication channel lists Research funding Scholarly communication Journal ranking

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概念视角下信息计量学的三个层面

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图书馆理论与实践 2014年第9期 46-50页

作者： raf Guns 王岗不详宁夏图书馆银川750011

简要回顾信息计量学研究内容的现行模型,并就模型的记录层面、社会层面、认知层面分别进行了讨论;在此基础上,讨论了每个层面内部以及层面之间的关系,并特别论述了引用关系的性质,研究了映射、距离远近以及影响等概念在该模型中的位置。

关键词：信息计量学文献计量学引用实体-关系模型概念模型信息信息检索

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Gasification of plastic waste as waste-to-energy or waste-to-syngas recovery route

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Natural Science 2013年第6期5卷 695-704页

作者： Anke Brems raf Dewil Jan Baeyens Rui Zhang College of Life Science and Technology The Key Laboratory of Bioprocess of Beijing Beijing University of Chemical Technology Beijing China Department of Chemical Engineering Chemical and Biochemical Process Technology and Control Section Katholieke Universiteit Leuven Heverlee Belgium

The disposal of plastic solid waste (PSW) has become a major worldwide environmental problem. New sustainable processes have emerged, i.e. either advanced mechanical recycling of PSW as virgin or second grade plastic feedstock, or thermal treatments to recycle the waste as virgin monomer, as synthetic fuel gas, or as heat source (incineration with energy recovery). These processes avoid land filling, where the non-biodegradable plastics remain a lasting environmental burden. Within the thermal treatments, gasification and pyrolysis gain increased interest. Gasification has been widely studied and applied for biomass and coal, with results reported and published in literature. The application to the treatment of PSW is less documented. Gasification is commonly operated at high temperatures (> 600℃ to 800℃) in an air-lean environment (or oxygen-deficient in some applications): the air factor is generally between 20% and 40% of the amount of air needed for the combustion of the PSW. Gasification produces mostly a gas phase and a solid residue (char and ashes). The use of air introduces N2 in the product gases, thus considerably reducing the calorific value of the syngas, because of the dilution. The paper will review the existing literature data on PSW gasification, both as the result of laboratory and pilot-scale research. Processes developed in the past will be illustrated. Recently, the use of a sequential gasification and combustion system (at very high temperatures) has been applied to various plastic-containing wastes, with atmospheric emissions shown to be invariably below the legal limits. Operating results and conditions will be reviewed in the paper, and completed with recent own lab-scale experimental results. These results demonstrate that gasification of PSW can be considered as a first order reaction, with values of the activation energy in the order of 187 to 289 kJ/mol as a function of the PSW nature.

关键词： Plastic Waste Re-use Gasification Syngas Char Sustainability Reaction Rate

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