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51.
  • Brethes, Anaïs (författare)
  • An integrated study of geological, magnetic and electromagnetic data for mineral exploration in the Jameson Land Basin, central East Greenland
  • 2018
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • The Jameson Land Basin, located in central East Greenland, initiated in Devonian time with the collapse of the over-thickened Caledonian Orogen. The basin developed during different phases of rifting from the late Paleozoic to the Mesozoic and has accumulated between 16-18 km of sediments. In Paleogene time, the basin was affected by intense magmatism due to the opening of the North Atlantic Ocean c. 55 Ma ago. Due to a significant uplift in Miocene time, the sedimentary sequence is well exposed along the basin margins, revealing numerous mineral occurrences hosted within almost the entire stratigraphic succession. The major types of mineralization comprise: (1) intrusion-related Mo (± Pb, Zn, Cu, Ag) mineralization associated with Paleogene intrusive complexes; (2) stratabound and/or stratiform Cu, Pb, Zn, (Ag) within Upper Permian and Triassic clastic and marine sedimentary formations; (3) stratabound and structurally controlled Pb-Zn, Cu, Ba, (Sr) mineralization in Upper Permian carbonates; and (4) structurally-controlled Pb, Zn, Cu (±Sb, Bi, Ag, Au) vein-type mineralization within Caledonian and Paleozoic rocks.It is well acknowledged that structures such as faults, thrusts, detachments, shear zones and associated fracture systems play an important role as fluid conduits connecting metal sources and sites of mineral precipitation. In particular, previous studies showed that mineral occurrences within the East Greenland Caledonides are closely related to lineaments and intrusions. In this context, the Crusmid-3D project was initiated in 2014, aiming at establishing the links between the crustal structures and the mineral occurrences in the Jameson Land Basin using a combination of geological and geophysical data. The interest for mineral exploration in the area led exploration companies and institutions to carry out magnetic and electromagnetic surveys, and the data derived from these constitute the base of this study.This thesis provides a detailed structural interpretation of aeromagnetic data in the Jameson Land Basin where several magnetic trends associated with Tertiary dikes and sills as well as with reactivated Paleozoic and Triassic faults were delineated. These data, in combination with a literature review and compilation of the mineral occurrences in the Jameson Land Basin, allowed highlighting seven prospective areas for structurally-controlled base metal mineralization.New structural data from geological fieldwork, drilling results and geophysical data (magnetic, electromagnetic and seismic data) along the eastern margin of the basin allowed a new interpretation of the geometry of the Triassic rift in East Greenland, represented by NE-SW-trending basins and highs segmented by NW-SE-trending transfer zones. It can be correlated with its European conjugate margin, displaying analogies with the Triassic Froan and Helgeland Basins in the Norwegian offshore and with the Papa and West Shetlands Basins north of the Shetland Islands.The proposed structural model of the Triassic rift was further investigated using 3D-geologically-constrained inversion of magnetic data in order to refine the architecture of the eastern margin of the Jameson Land Basin. Modelling results confirmed the presence of a shallow westward dipping peneplained crystalline basement in the southern part of the area while the northern part is characterized by faulted blocks, which accommodated relatively thick red bed sedimentary sequences, thereby representing a good potential source of base metals.Furthermore, Induced Polarization (IP) effects observed in airborne time-domain electromagnetic data acquired in the eastern margin of the basin were investigated using Self-Organizing Maps (SOM). The analysis of the shape and amplitude of the transient response curves using the SOM allowed identifying four areas where the transient curve patterns exhibit strong IP effects. These are shown to be collocated with Tertiary sills and dikes, clay-altered rocks as well as with a sulfide-bearing brecciated granite and with Triassic stratigraphic horizons hosting disseminated base metal sulfides.
52.
  • Broström, Robert (författare)
  • Design implications for visual-manual interfaces in cars
  • 2016
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • During the past decades there has been an extensive evolution in computer and communication technologies. In the last ten years these technologies have become an integrated part of our cars via in-vehicle information systems. Considerable efforts are put into research and development of the interface between the in-vehicle information systems and the driver. Due to the fact that vision is imperative in driving, the focus is in particular on the visual-manual interface and on apt usability evaluation methods.The purpose of this thesis is to study design implications for the development of visual-manual interfaces in cars. A point of departure is that the practice of the usability concept, usability evaluation methods, and compliance tests has implications for the design process.Four papers are appended to the thesis. Paper I focuses on differences between rotary control and touch screen interfaces in terms of driving simulator and glance metrics. Paper II investigates correlations between data from customer evaluations and expert evaluations for visual-manual interfaces. Paper III searches for the presence of and possible explanations for individual glance strategies in a driving simulator study. Paper IV investigates effects of individual glance strategies on the NHTSA visual-manual distraction test in a driving simulator set-up.In the thesis it is concluded that the optimal input device is dependent on the task being performed, that is, the touch screen is more efficient for alphanumeric input while rotary control performs list scrolling more efficiently. In addition, drivers seem to adapt their glance behaviour based on the display position. It is evident that efficiency metrics correlate between several usability evaluation methods. Hence, it is possible to generalise results from expert evaluations at an early design phase, to customer survey samples based on car ownership. Concerning glance behaviour, it is clear that individual glance strategies exist. Especially interesting are two glance strategies, long glancers and frequent glancers, that affect the results of the NHTSA compliance testing. These glance strategies have to be controlled for in the test situation. Finally, a framework is proposed that combines a classification of visual-manual actions with different visual fixations. The task analysis framework has the potential to analyse actions in terms of required visual resources, thus already providing an evaluation of visual-manual interfaces in the concept phase.
53.
  • Brown, Terrence, 1962- (författare)
  • An Evaluation of Crowdsourcing as a Tool  for Marketing Activities
  • 2019
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • Advances in technology and social media have facilitated the rapid development of crowdsourcing as an innovative tool within the field of marketing. This has driven researchers to investigate more deeply the phenomenon of crowdsourcing as a marketing innovation. The overall purpose of this thesis is expressed as: To explore and describe the use of crowdsourcing within the field of marketing. More specifically, the primary purpose of the thesis is to understand better - How crowdsourcing can be used as a marketing tool. This thesis aims to illuminate the gap in the extant marketing literature by reviewing current academic knowledge surrounding crowdsourcing and marketing.  The use of the crowd as a marketing tool is growing primarily because of the advent of the Internet; however, as technology continues to advance the possibilities, challenges and side effects of crowdsourcing also change. These also need to be investigated continually. More specifically as digital marketing moves from a Web 2.0 environment to a Web 3.0 environment there will be new opportunities as well as pitfalls. As a result, new and relevant marketing problems exist at the nexus of crowdsourcing and marketing.The research problem is sub-divided into the following four research questions:RQ1:  To what extent are crowdfunding platforms accessible to organizations as a marketing channel and, if so, what role can these platforms play?RQ2:  How will the shift from Web 2.0 (and active-user input) to Web 3.0(and passive-data/sensor–based input) impact the new opportunities/product development process?RQ3:  How can user-generated content help firms make strategic decisions about new business opportunities? RQ4:  How is the evolution of crowdsourcing impacting information externalities and consumer privacy and how is this impacting marketing? This research is further divided into two sections. The first part investigates marketing activities specifically new opportunities/product development, advertising and promotion, and marketing research. The second section focuses on one of the possible repercussions of crowdsourcing in the marketing process. Most research on crowdsourcing focuses on the first section (i.e., the marketing activities) and how crowdsourcing is a positive marketing tool. Much less research aims its attention on the consequences and/or potential negative aspects of crowdsourcing.This thesis consists of two published papers and two studies. Each project handles one of research questions. The first two papers and the first study focus on three marketing activities (i.e., advertising, promotion and sales, new product and service development, and market research). The second study focuses on one of the possible consequences of the growth of crowdsourcing as a tool in the marketing process.While each paper and study has its own individual contributions, the overall contribution of this study is multi-fold. First, it develops a definition of crowdsourcing as: a tool or process by which the firm can increase or expand the resources to which it has access to by using the collective effort of a group of individuals or organizations. Second, as a result of these four research projects, crowdsourcing can further be seen as a situational, contextual and flexible tool that can be used in many different organizational contexts. The specific context for this thesis is marketing and as a result, crowdsourcing can play a wide variety of marketing roles.
54.
  • Brämming, Mats (författare)
  • An Operational View on Foaming and Slopping Control in Top-blown BOS Vessels
  • 2015
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • Slag formation plays a decisive role in all steelmaking processes. In top-blowing Basic Oxygen Steelmaking (BOS) i.e., in the LD process, an emulsion consisting of liquid slag, dispersed metal droplets, undissolved particles and solid precipitates will, together with process gases, form an expanding foam. Extensive research has defined the parameters that govern the foaming characteristics of BOS slag-metal emulsions. It is a well-known fact that certain process conditions in the Basic Oxygen Furnace (BOF) will lead to excessive foam growth, forcing foam out through the vessel opening (mouth). This process event is commonly known as slopping. Slopping results in loss of valuable metal, equipment damage, lost production time, unsafe work environment and pollution. A literature survey covering the slopping phenomena has been carried out, as well as a deeper investigation into the causes behind slopping on the BOF type LD/LBE at SSAB Europe, Luleå, equipped with an automatic system for slopping registration using image analysis Good slag formation and foam-growth control in order to avoid slopping is primarily accomplished by taking preventive “static” measures. The most common pre-blowing operational conditions favouring foam growth and, hence, slopping were found to be linked to oxygen lance positioning, hot metal Si and Mn contents, scrap quality and large additions of iron oxide bearing materials. Improved slopping control may be achieved by developing oxygen lance control schemes with automatic adjustment of the distance between the lance tip and the metal bath (i.e., the lance gap) according to scrap quality and ore additions. If “static” measures cannot be effectuated, a set of in-blow slopping preventive measures is needed. For such “dynamic” measures to be effective, it is necessary to have a system for slopping prediction. Trials with vessel vibration measurements for indirect foam height estimation in industrial scale BOFs, type LD/LBE, have been carried out. FFT spectrum analysis was applied in order to find the frequency band with best correlation to an estimated foam height. The results show that there is a correlation between vessel vibration and foam height which can be used for dynamic foam level and slopping control, and this during the entire blow. The vessel vibration results have been tested against what is the perhaps most commonly implemented technique for dynamic foam height estimation and slopping control, the audiometric system. Parallel vibration and audio measurements have been carried out on 130-tonne as well as on 300-tonne BOFs. The results show that during stable process conditions there is good agreement between the two methods in regard to foam height estimation and that combining the two methods will provide a powerful slopping prediction and control system. A feasibility study has been carried out with the aim to describe the possibilities and limitations of multivariate data analysis, including batch analysis, for dynamic BOS process control, mainly in regard to slopping prevention. Two principal modelling approaches were tested.A central part of this PhD work is the performed emulsion characterisation and the subsequent investigation into the influence of emulsion mineralogy and morphology on slopping in the LD process. The results are based on the study of emulsion samples from trial heats conducted in a 6-tonne pilot plant LD vessel. The main emulsion slag phase mineral species identified were di-calcium silicate, monoxides (mainly FeO, MnO and MgO), calcium ferrites and late-appearing tri-calcium silicate. The study also show that the iron oxidation state has a large influence on the emulsion mineralogy and morphology, as a higher Fe3+ content facilitates the precipitation of calcium ferrites, raising the emulsion apparent viscosity and, hence, the foam index. The same effect is caused by higher MgO contents (i.e., at saturation), resulting in the precipitation of monoxide phase. However, large volume fractions of emulsion precipitates will not always lead to slopping in the LD process. A second “requirement” for excessive foam growth is a simultaneously high gas generation rate. Vice versa; an LD heat may very well slop at low volume fractions of 2ndphase particles in the emulsion if the gas generation rate is sufficiently high. It is an indisputable fact that excessive foaming is one of the main features of the LD process, due to the practice of top-lance oxygen blowing, creating a highly oxidised slag, and heavy batch additions of basic slag formers, causing an initial formation of large quantities of precipitates. Therefore, preventing slopping is primarily a matter of tight process control, most importantly, control of the oxygen lance gap in order to reach a state of sufficiently high liquid MeO phase to minimise the emulsion apparent viscosity, but low enough to avoid over-oxidising and a high gas generation rate.
55.
  • Burström, Per (författare)
  • Computational Fluid Dynamics of Processes in Iron Ore Grate-Kiln Plants
  • 2015
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • Computational Fluid Dynamics (CFD) approaches have been developed to studypollution reduction in the manufacturing phase and heat transfer in the packed beds of iron ore pellets. CFD is a versatile tool that can be applied to study numerous problems in fluid mechanics. In the present thesis it is used, verified and validated to reveal the fluid mechanics of a couple of processes taking place during the drying and sintering of iron ore pellets. This is interesting in itself and can facilitate the optimization of the production as to product quality of the pellets, reduced energy consumption and reduction of emissions such as NOx and CO2. The practical aim with the pollution reduction research project is to numerically study the use of Selective Non-Catalytic Reduction (SNCR) technologies in gratekiln pelletizing plants for NOx reduction which had, to the best knowledge of the author, never been used in this context before despite that it is commonly used in cement and waste incineration plants. The investigation is done in several stages: 1)Reveal if it is possible to use the technique with the two most commonly reagents, ammonia and urea. 2) Derive a chemistry model for cyanuric acid (CA) so that this reagent also can be scrutinized. 3) Compare the reagents urea and CA in the gratekiln pelletizing process.A CFD model was developed and numerical simulations were carried out solving the flow field. A model for spray injection into the grate was then included in the model enabling a study of the overall mixing between the injected reagent droplets and the NOx polluted air. The results show that the SNCR technique with urea and CA may reduce the amount of NOx in the grate-kiln process under certain conditions while ammonia fails under the conditions investigated. The work also lays grounds for continued development of the proposed chemistry model by the adding of reactions to the RAPRENOx-process for CA as reagent, facilitating an extension to ammonia and urea as reagents.The grate-kiln plant consists of a grate, a rotating kiln and an annular cooler. The pellets are loaded onto the grate to shape a bed with a mean height of about 0.2 m. The pellets in LKABs processes consist mainly of magnetite and different additives chosen to fit the demand from the customer. Throughout the grate a temperature gradient is formed in the bed. This gradient should be as even as possible throughout the grate to ensure an even quality of the pellets. Method to study this numerically is the second main task in this thesis. The aim is to find out how temperature distributions in the bed can be modeled and adjusted. Of special interest is how the incoming process gas, leakage, and the detailed composition of the pellet bed influence the heat transfer through the bed. To achieve the goals and create a trustful model for the heat transfer through the packed bed the model must be build up in steps. Heat transfer to a bed of iron ore pellets is therefore examined numerically on several scales and with three methods: a one-dimensional continuous model, a discrete three-dimensional model and traditional computational fluid dynamics.In a first study the convective heat transport in a relatively thin porous layer ofmonosized particles is set-up and computed with the one-dimensional continuous model and the discrete three-dimensional model. The size of the particles is only one order of magnitude smaller than the thickness of the layer. For the three-dimensional model the methodology applied is Voronoi discretization with minimization of dissipation rate of energy. The discrete model captures local effects, including low heat transfer in sections with low speed of the penetrating fluid and large velocity and temperature variations in a cross section of the bed. The discrete and continuousmodel compares well for low velocities for the studied uniform boundary conditions. When increasing the speed or for a thin porous layer however, the continuous model diverge from the discrete approach if a constant dispersion is used in the continuous approach. The influence is larger from an increase in pellet diameter to bed height ratio than from increased velocity. In a second study the discrete model is compared to simulations performed with CFD. If local values are of importance the discrete model should always be used but if mean predictions are sufficient the CFD model isan attractive alternative that is easy to couple to the physics up- and downstream the packed bed. The good agreement between the discrete and continuous model furthermore indicates that the discrete model may be used also for non-Stokian flow in the transitional region between laminar and turbulent flow, as turbulent effects show little influence of the overall heat transfer rates in the continuous model.
56.
  • Byström, Alexandra (författare)
  • Compartment Fire Temperature Calculations and Measurements
  • 2017
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • Denna avhandling behandlar problem kopplade till värmeöverföring och branddynamik i slutna utrymmen med tonvikt på värmeöverföring mellan gaser och utsatta konstruktioner. Avhandlingen består av en huvuddel och ett appendix innehållande sju vetenskapliga artiklar. I huvuddelen sammanfattas och diskuteras grundläggande teorier och principer inom värmeöverföring och branddynamik samt studier av ett antal specialfall av brandscenarion som baseras på dessa teorier. I de avslutande bilagorna (Artiklar A1-A3 och Artiklar B1-B2) finns sju vetenskapliga artiklar som grundligare beskriver de ovan nämnda specialfallen.Huvudfokus i avhandlingen ligger på temperaturutveckling vid brand i slutna utrymmen. I avhandlingen studeras i synnerhet en- och två-zonsmodeller för brand i slutna utrymmen, och en ny metod för att beräkna brandgastemperaturer före och efter övertändning i rumsbränder är framtagen. Validering av dessa modeller med experiment visar att deras noggrannhet är bra. Modellerna visar också att de termiska egenskaperna hos de omgivande ytorna har stor inverkan på brandtemperatursutvecklingen. I tillägg studeras i denna avhandling betydelsen av val av mätmetoder i brandtekniska tillämpningar. På grundval av slutsatserna från dessa studier har de främsta mätteknikerna använts i ytterligare experimentella studier av olika brandscenarier.
57.
  • Bäckström, Lars (författare)
  • Svensk gruvrätt En rättsvetenskaplig studie rörande förutsättningarna för utvinning av mineral
  • 2015
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • Swedish landowners Historically, Swedish landowners have been forced to accept that that their land is claimed for mining activities. This has been done on the basis of different laws and legal rules. The Minerals Act currently in force also entitles third parties to extract miner-als from other people's property. The question of who owns the mineral prior to extraction is however not answered by the Minerals Act or by any other statute. The ownership issue is, in addition to principally interesting, also of practical importance, for instance in relation to the right to exploit minerals covered by the Minerals Act for household use, or the right to exploit unregulated minerals, as well as for future discussion regarding mineral compensation. Besides the principal question of ownership, the Minerals Act gives rise to a number of other issues affecting the landowner's right in relation to the extraction of minerals on the property. The main purpose of the study in Part I is to identify who, if anyone, under Swedish law can be regarded as the principal owner of the components of earth that contain minerals. To this end, it has been necessary to define the concept of ownership in the property context. Access to minerals has been essential for the development of civilization and is still of crucial importance for the way we live our lives. While mineral extraction can be said to constitute a significant public interest, it is an activity that claims limited resources, competes with other land-use interests and causes significant environmental impacts. Even these interests have gradually begun to be considered public and essential, especially the interest of sustainable development. As a result of this, the legal framework governing the extraction of minerals has expanded substantially. This applies not least in relation to other interests, such as environ-mental protection and the rights of others, for example various types of user rights. The legal framework for mineral extraction is today a complex system consisting of several laws with wholly or partly different objectives. An important question is how well these overarching objectives can be ensured within the licensing process for mineral extraction and its associated parallel application of more or less independent laws. The main purpose of the study in Part II is to examine how the overarching objective of the Environmental Code is safeguarded in the licensing process for mineral extraction, and how the process should be designed in order for it to result in well-balanced solutions where all interests are given sufficient consideration. In addition to the analysis of the various legal issues and conflicts that may arise in connection with the exploration, exploitation and processing of minerals, the study also aims to investi-gate what should be regarded as applicable law in situations where clear rules are missing.
58.
  • Calner, Tommy (författare)
  • Persistent musculoskeletal pain A web-based activity programme for behaviour change, does it work? Expectations and experiences of the physiotherapy treatment process
  • 2018
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • This thesis concerned persons with persistent musculoskeletal pain in primary health care and had three aims. The first aim was to evaluate the effects of a web-based programme for behaviour change. The second aim was to create and evaluate a multimodal intervention. The third aim was to explore and describe expectations andexperiences of the physiotherapy treatment process.In Study I, we evaluated the effects of a web-based activity programme for behaviour change added to multidisciplinary rehabilitation (MDR) in primary health care. Ninety-nine participants were randomized to 1) MDR with an additional web-based programme, and 2) MDR. Outcome measures were work ability, pain intensity, pain-relate disability and health-related quality of life. There were no significant effects of the web-based programme for any outcome measure at 4 or 12 months. In conclusion, this study provides no support for adding a self-guided web-based programme to MDR in primary health care.In Study II, we evaluated first the web-based programme from Study I compared to the waiting list. Effect measures were workability, pain intensity, disability and self-efficacy. Thereafter, we evaluated the effects and process of a novel multimodal intervention consisting of the web-based programme with additional individual counselling, and individually tailored physiotherapy treatment. Ten participants were included in the study. Effects were evaluated using a Single Subject Experimental Design (SSED) and the process was evaluated by interviews with the participants and log data of usage of the modalities. There were no conclusive effects of the self-managed web-based programme as compared to the waiting list. The SSED analyses of the multimodal intervention showed promising short-term results regarding disability and pain intensity, but no conclusive results for work ability or self-efficacy. The multi-modal intervention process seemed successfully implemented, and the importance of physiotherapy and, to some extent counselling, was emphasized by the participants. In conclusion, the newly designed multimodal intervention in primary health care seemed feasible and showed some promising short-term effects, while the implementation of a self-managed web-based programme as a single intervention seemed without effect.In Study III, qualitative interviews were conducted with ten participants to explore their expectations of physiotherapy. Data were analysed with qualitative content analysis and the findings described a multi-faceted picture of the participants’ expectations, encompassing several aspects regarding the treatment process and outcome. Regarding the treatment process, participants expected a good dialogue, to be confirmed as individuals, and to get an explanation for their pain. The participants expected tailored training with frequent follow-ups and their expectations of outcome ranged from hope of the best possible results to being realistic or resigned.In Study IV, qualitative interviews were conducted with 11 participants to explore their experiences in physiotherapy treatment. Data were analysed with qualitative content analysis. The findings show how the participants described how they used knowledge, awareness, movements and exercises learned from the physiotherapy treatment to develop strategies to manage pain and the process of acceptance. There were experiences involving the importance of establishing an alliance with the physiotherapist, based on trust and with a continuous dialogue. When exercises, activities and other treatment modalities were individualized, participants were actively involved in the process. This was rewarding but was also considered an effort and a challenge. The physiotherapist’s initiatives and actions were considered important for incentive and support.In conclusion, we found no effects of the web-based activity programme on behaviour change for persons with persistent musculoskeletal pain. The newly designed multi-modal intervention in primary health care seemed feasible and showed some promising short-term effects. Expectations of physiotherapy treatment were multi-faceted, encompassing both process and outcome. After finishing physiotherapy, the participants described how they used knowledge, awareness, movements and exercises learned from the physiotherapy treatment to develop strategies to manage pain and the process of acceptance. The importance of alliance and incentives for activities throughout the physiotherapy treatment process were also described.
59.
  • Capaci, Francesca (författare)
  • Adapting Experimental and Monitoring Methods for Continuous Processes under Feedback Control : Challenges, Examples, and Tools
  • 2019
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • Continuous production covers a significant part of today’s industrial manufacturing. Consumer goods purchased on a frequent basis, such as food, drugs, and cosmetics, and capital goods such as iron, chemicals, oil, and ore come through continuous processes. Statistical process control (SPC) and design of experiments (DoE) play important roles as quality control and product and process improvement methods. SPC reduces product and process variation by eliminating assignable causes, while DoE shows how products and processes may be improved through systematic experimentation and analysis. Special issues emerge when applying these methods to continuous process settings, such as the need to simultaneously analyze massive time series of autocorrelated and cross-correlated data. Another important characteristic of most continuous processes is that they operate under engineering process control (EPC), as in the case of feedback controllers. Feedback controllers transform processes into closed-loop systems and thereby increase the process and analysis complexity and application of SPC and DoE methods that need to be adapted accordingly. For example, the quality characteristics or process variables to be monitored in a control chart or the experimental factors in an experiment need to be chosen considering the presence of feedback controllers.The main objective of this thesis is to suggest adapted strategies for applying experimental and monitoring methods (namely, DoE and SPC) to continuous processes under feedback control. Specifically, this research aims to [1] identify, explore, and describe the potential challenges when applying SPC and DoE to continuous processes; [2] propose and illustrate new or adapted SPC and DoE methods to address some of the issues raised by the presence of feedback controllers; and [3] suggest potential simulation tools that may be instrumental in SPC and DoE methods development.The results are summarized in five appended papers. Through a literature review, Paper A outlines the SPC and DoE implementation challenges for managers, researchers, and practitioners. For example, the problems due to process transitions, the multivariate nature of data, serial correlation, and the presence of EPC are discussed. Paper B describes the issues and potential strategies in designing and analyzing experiments on processes operating under closed- loop control. Two simulated examples in the Tennessee Eastman (TE) process simulator show the benefits of using DoE methods to improve these industrial processes. Paper C provides guidelines on how to use the revised TE process simulator under a decentralized control strategy as a testbed for SPC and DoE methods development in continuous processes. Papers D and E discuss the concurrent use of SPC in processes under feedback control. Paper D further illustrates how step and ramp disturbances manifest themselves in single-input single-output processes controlled by variations in the proportional-integral-derivative control and discusses the implications for process monitoring. Paper E describes a two-step monitoring procedure for multivariate processes and explains the process and controller performance when out-of-controlprocess conditions occur.
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60.
  • Cardenas, Edgar, 1990- (författare)
  • Synthesis of zeolites from economic raw materials
  • 2019
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • Synthesis methods using economic raw materials, such as kaolin and diatomite have been developed for the production of zeolites in the present work. Zeolite Y and ZSM-5 have been synthetized successfully from diatomite and kaolin, respectively. The synthesis of zeolite Y was extensively studied (Paper I) in order to obtain final products with high crystallinity and an appropriate SiO2/Al2O3 ratio to be suitable for application as catalyst. Then, the influence of the alkalinity (in terms of SiO2/Na2O ratio) on the outcome of the synthesis was studied. Thus, an optimum range of alkalinity that satisfies the requirements stated before was found. Additionally, the results also showed that diatomite produce similar products as colloidal silica, which may be expected since both silica sources are highly polymerized forms of silica.The synthesized zeolite Y crystals were also ion-exchanged with Lanthanum to obtain a Rare Earth zeolite Y (REY) catalyst (Paper V).  The REY catalyst was shown to be thermally stable up to 800°C as expected for this catalyst. The REY catalyst was also evaluated in the reaction of Catalytic Cracking of cumene. The results of catalytic tests shown that the REY catalyst synthetized from diatomite holds activity towards the catalytic cracking of cumene.In addition, studies of synthesis of ZSM-5 zeolite from kaolin have been performed to understand the crystal growth and morphology, crystal size, and aluminum distribution. In particular, the influence of the gel on the morphology of the crystals (Paper II) has been studied. It was observed that when the crystal surface is in contact with the gel phase, dendritic features appear at the crystal surface, that become smoother as the reaction proceeds. On the contrary, when only liquid phase is in contact with crystal surface there is no presence of dendritic features and the growth rate is higher.Further studies demonstrated that the ZSM-5 crystals possess a non-homogeneous aluminum distribution, a phenomenon known as Al-zoning.  A thorough characterization at distinct stages of the reaction has been performed (Paper III), on the different reaction mixture phases such as solid part, gel phase and liquid phase. The main finding was that the gel phase consists of a nanoparticle skeleton rich in alumina, filled by a silica rich matrix. In the beginning of crystallization, the silica rich matrix is preferentially consumed to form the crystals, leaving behind the alumina rich nanoparticle skeleton that is consumed later, resulting in the non-homogeneous distribution of aluminum in the crystals.Finally, studies of the microstructure of a TPA-ZSM-5 system using fumed silica as silicon source have been performed (paper IV). In this system, three stages of crystallization were observed. Stage I, formation of amorphous gel phase. Stage II formation of XRD amorphous spherical entities denoted as Condensed Agregates (CAs). Stage III, Crystallization of CAs into ZSM-5. This study was focused only in the stage III. Findings showed that ZSM-5 nanocrystals are formed in the core of the CA (beginning of stage III), surrounded by an amorphous shell composed of alumino-silica. As the crystallization proceeds, the amorphous shell crystallizes into ZSM-5 by competitive growth, but the nanocrystals of the core remain intact. Moreover, compositional analysis results showed that the silicon from the liquid phase provided most of the nutrients for growth of the ZSM-5 crystals resulting in polycrystalline ZSM-5 aggregates with an Al rich core - Si rich shell morphology.
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