Development of a process for the direct synthesis of hydrogen peroxide in a novel microstructured reactor

Microreactors have proven to be versatile tools for process intensification. Over recent decades, they have increasingly been used for product and process development in chemical industries. Enhanced heat and mass transfer in the reactors due to the extremely high surfacearea- to-volume ratio and interfacial area allow chemical processes to be operated at extreme conditions. Safety is improved by the small holdup volume of the reactors and effective control of pressure and temperature. Hydrogen peroxide is a powerful green oxidant that is used in a wide range of industries. Reduction and auto-oxidation of anthraquinones is currently the main process for hydrogen peroxide production. Direct synthesis is a green alternative and has potential for on-site production. However, there are two limitations: safety concerns because of the explosive gas mixture produced and low selectivity of the process. The aim of this thesis was to develop a process for direct synthesis of hydrogen peroxide utilizing microreactor technology. Experimental and numerical approaches were applied for development of the microreactor. Development of a novel microreactor was commenced by studying the hydrodynamics and mass transfer in prototype microreactor plates. The prototypes were designed and fabricated with the assistance of CFD modeling to optimize the shape and size of the microstructure. Empirical correlations for the mass transfer coefficient were derived. The pressure drop in micro T-mixers was investigated experimentally and numerically. Correlations describing the friction factor for different flow regimes were developed and predicted values were in good agreement with experimental results. Experimental studies were conducted to develop a highly active and selective catalyst with a proper form for the microreactor. Pd catalysts supported on activated carbon cloths were prepared by different treatments during the catalyst preparation. A variety of characterization methods were used for catalyst investigation. The surface chemistry of the support and the oxidation state of the metallic phase in the catalyst play important roles in catalyst activity and selectivity for the direct synthesis. The direct synthesis of hydrogen peroxide was investigated in a bench-scale continuous process using the novel microreactor developed. The microreactor was fabricated based on the hydrodynamic and mass transfer studies and provided a high interfacial area and high mass transfer coefficient. The catalysts were prepared under optimum treatment conditions. The direct synthesis was conducted at various conditions. The thesis represents a step towards a commercially viable direct synthesis. The focus is on the two main challenges: mitigating the safety problem by utilization of microprocess technology and improving the selectivity by catalyst development.

Model based analysis of the post-combustion calcium looping process for carbon dioxide capture

This thesis presents a one-dimensional, semi-empirical dynamic model for the simulation and analysis of a calcium looping process for post-combustion CO2 capture. Reduction of greenhouse emissions from fossil fuel power production requires rapid actions including the development of efficient carbon capture and sequestration technologies. The development of new carbon capture technologies can be expedited by using modelling tools. Techno-economical evaluation of new capture processes can be done quickly and cost-effectively with computational models before building expensive pilot plants. Post-combustion calcium looping is a developing carbon capture process which utilizes fluidized bed technology with lime as a sorbent. The main objective of this work was to analyse the technological feasibility of the calcium looping process at different scales with a computational model. A one-dimensional dynamic model was applied to the calcium looping process, simulating the behaviour of the interconnected circulating fluidized bed reactors. The model incorporates fundamental mass and energy balance solvers to semi-empirical models describing solid behaviour in a circulating fluidized bed and chemical reactions occurring in the calcium loop. In addition, fluidized bed combustion, heat transfer and core-wall layer effects were modelled. The calcium looping model framework was successfully applied to a 30 kWth laboratory scale and a pilot scale unit 1.7 MWth and used to design a conceptual 250 MWth industrial scale unit. Valuable information was gathered from the behaviour of a small scale laboratory device. In addition, the interconnected behaviour of pilot plant reactors and the effect of solid fluidization on the thermal and carbon dioxide balances of the system were analysed. The scale-up study provided practical information on the thermal design of an industrial sized unit, selection of particle size and operability in different load scenarios.

Computational modeling of the properties of TiO2 nanoparticles

In this study we discuss the electronic, structural, and optical properties of titanium dioxide nanoparticles, and also the properties of Ni(II) diimine dithiolato complexes as dyes in dye-sensitized TiO2 based solar cells. The abovementioned properties have been modeled by using computational codes based on the density functional theory. The results achieved show slight evidence on the structure-dependent band gap broadening, and clear blue-shifts in absorption spectra and refractive index functions of ultra-small TiO2 particles. It is also shown that these properties are strongly dependent on the shape of the nanoparticles. Regarding the Ni(II) diimine dithiolato complexes as dyes in dye-sensitized TiO2 based solar cells, it is shown that based on the experimental electrochemical investigation and DFT studies all studied diimine derivatives could serve as potential candidates for the light harvesting, but the e ciencies of the dyes studied are not very promising.

Computational studies for the design of process equipment with complex geometries

This study combines several projects related to the flows in vessels with complex shapes representing different chemical apparata. Three major cases were studied. The first one is a two-phase plate reactor with a complex structure of intersecting micro channels engraved on one plate which is covered by another plain plate. The second case is a tubular microreactor, consisting of two subcases. The first subcase is a multi-channel two-component commercial micromixer (slit interdigital) used to mix two liquid reagents before they enter the reactor. The second subcase is a micro-tube, where the distribution of the heat generated by the reaction was studied. The third case is a conventionally packed column. However, flow, reactions or mass transfer were not modeled. Instead, the research focused on how to describe mathematically the realistic geometry of the column packing, which is rather random and can not be created using conventional computeraided design or engineering (CAD/CAE) methods. Several modeling approaches were used to describe the performance of the processes in the considered vessels. Computational fluid dynamics (CFD) was used to describe the details of the flow in the plate microreactor and micromixer. A space-averaged mass transfer model based on Fick’s law was used to describe the exchange of the species through the gas-liquid interface in the microreactor. This model utilized data, namely the values of the interfacial area, obtained by the corresponding CFD model. A common heat transfer model was used to find the heat distribution in the micro-tube. To generate the column packing, an additional multibody dynamic model was implemented. Auxiliary simulation was carried out to determine the position and orientation of every packing element in the column. This data was then exported into a CAD system to generate desirable geometry, which could further be used for CFD simulations. The results demonstrated that the CFD model of the microreactor could predict the flow pattern well enough and agreed with experiments. The mass transfer model allowed to estimate the mass transfer coefficient. Modeling for the second case showed that the flow in the micromixer and the heat transfer in the tube could be excluded from the larger model which describes the chemical kinetics in the reactor. Results of the third case demonstrated that the auxiliary simulation could successfully generate complex random packing not only for the column but also for other similar cases.

Enabling Change in Universities: Enhancing Education for Sustainable Development with Tools for Quality Assurance

Enabling Change in Universities: Enhancing Education for Sustainable Development with Tools for Quality Assurance This thesis deals with enabling change in universities, more explicitly enhancing education for sustainable development with tools for quality assurance. Change management is a discipline within management that was developed in the 1980s because business changed from being predictable to unpredictable. The PEST mnemonic is a method to categorize factors enabling change; such as political, economic, socio-cultural and technological factors, which all affect higher education. A classification of a change, in either hard or soft, can help understanding the type of change that an organization is facing. Hard changes are more applied to problems that have clear objectives and indicators, with a known cause of the problem. Soft changes are applied to larger problems that affect the entire organization or beyond it. The basic definition for sustainable development is: the future generations should have similar opportunities as the previous. The UN has set as a global goal an integration of education for sustainable development (ESD) at all levels of education during 2005- 2014. The goal is set also in universities, the graduates of which are future leaders for all labor markets. The objective for ESD in higher education is that graduates obtain the competence to take economic, social and environmental costs and benefits into account when making decisions. Knowledge outcomes should aim for systematic and holistic thinking, which requires cross disciplinary education. So far, the development of ESD has not achieved its goals. The UN has identified a need for more transdisclipnary research in ESD. A joint global requirement for universities is quality assurance, the aim of which is to secure and improve teaching and learning. Quality, environmental and integrated management systems are used by some universities for filling the quality assurance requirements. The goal of this thesis is to open up new ways for enhancing ESD in universities, beyond the forerunners; by exploring how management systems could be used as tools for promoting ESD. The thesis is based on five studies. In the first study, I focus on if and how tools for quality assurance could be benefitted for promoting ESD. It is written from a new perspective, the memetic, for reaching a diversity of faculty. A meme is an idea that diffuses from brain to brain. It can be applied for cultural evolution. It is a theory that is based on the evolutionary theory by Darwin, applied for social sciences. In the second Paper, I present the results from the development of the pilot process model for enhancing ESD with management systems. The development of the model is based on a study that includes earlier studies, a survey in academia and an analysis of the practice in 11 universities in the Nordic countries. In the third study, I explore if the change depends on national culture or if it is global. It is a comparative study on both policy and implementation level, between the Nordic countries and China. The fourth study is a single case study based on change management. In this study, I identify what to consider in order to enable the change: enhancing ESD with tools for quality assurance in universities. In the fifth Paper, I present the results of the process model for enhancing ESD with management systems. The model was compared with identified drivers and barriers for enhancing ESD and for implementing management systems. Finally, the process model was piloted and applied for identifying sustainability aspects in curricula. Action research was chosen as methodology because there are not already implemented approaches using quality management for promoting ESD, why the only way to study this is to make it happen. Another reason for choosing action research is since it is essential to involve students and faculty for enhancing ESD. Action based research consists of the following phases: a) diagnosing, b) planning action, c) taking action and d) evaluating action. This research was made possible by a project called Education for Sustainable Development in Academia in the Nordic countries, ESDAN, in which activities were divided into these four phases. Each phase ended with an open seminar, where the results of the study were presented. The objective for the research project was to develop a process for including knowledge in sustainable development in curricula, which could be used in the quality assurance work. Eleven universities from the Nordic countries cooperated in the project. The aim was, by applying the process, to identify and publish examples of relevant sustainability aspects in different degree programs in universities in the Nordic countries. The project was partly financed by the Nordic Council of Ministers and partly by the participating pilot universities. Based on the results of my studies, I consider that quality, environmental and integrated management systems can be used for promoting ESD in universities. Relevant sustainability aspects have been identified in different fields of studies by applying the final process model. The final process model was compared with drivers and barriers for enhancing ESD and for implementing management systems in universities and with succeeding with management systems in industry. It corresponds with these, meaning that drivers are taken into account and barriers tackled. Both ESD and management systems in universities could be considered successful memes, which can reflect an effective way of communication among individuals. I have identified that management systems could be used as tools for hard changes and to support the soft change of enhancing ESD in universities with management system. Based on the change management study I have summarized recommendations on what to consider in order to enable the studied change. The main practical implications of the results are that the process model could be applied for assessment, benchmarking and communication of ESD, connected to quality assurance, when applied. This is possible because the information can be assembled in one picture, which facilitates comparison. The memetic approach can be applied for structuring. It is viable to make comparative studies between cultures, for getting insight in special characteristics of the own culture. Action based research is suitable for involving faculty. Change management can be applied for planning a change, which both enhancing ESD and developing management systems are identified to be.

Project Management Tools in Agile Embedded Systems Development

Agile methods have become increasingly popular in the field of software engineering. While agile methods are now generally considered applicable to software projects of many different kinds, they have not been widely adopted in embedded systems development. This is partly due to the natural constraints that are present in embedded systems development (e.g. hardware–software interdependencies) that challenge the utilization of agile values, principles and practices. The research in agile embedded systems development has been very limited, and this thesis tackles an even less researched theme related to it: the suitability of different project management tools in agile embedded systems development. The thesis covers the basic aspects of many different agile tool types from physical tools, such as task boards and cards, to web-based agile tools that offer all-round solutions for application lifecycle management. In addition to these two extremities, there is also a wide range of lighter agile tools that focus on the core agile practices, such as backlog management. Also other non-agile tools, such as bug trackers, can be used to support agile development, for instance, with plug-ins. To investigate the special tool requirements in agile embedded development, the author observed tool related issues and solutions in a case study involving three different companies operating in the field of embedded systems development. All three companies had a distinct situation in the beginning of the case and thus the tool solutions varied from a backlog spreadsheet built from scratch to plug-in development for an already existing agile software tool. Detailed reports are presented of all three tool cases. Based on the knowledge gathered from agile tools and the case study experiences, it is concluded that there are tool related issues in the pilot phase, such as backlog management and user motivation. These can be overcome in various ways epending on the type of a team in question. Finally, five principles are formed to give guidelines for tool selection and usage in agile embedded systems development.

Subshifts with Simple Cellular Automata

A subshift is a set of in nite one- or two-way sequences over a xed nite set, de ned by a set of forbidden patterns. In this thesis, we study subshifts in the topological setting, where the natural morphisms between them are ones de ned by a (spatially uniform) local rule. Endomorphisms of subshifts are called cellular automata, and we call the set of cellular automata on a subshift its endomorphism monoid. It is known that the set of all sequences (the full shift) allows cellular automata with complex dynamical and computational properties. We are interested in subshifts that do not support such cellular automata. In particular, we study countable subshifts, minimal subshifts and subshifts with additional universal algebraic structure that cellular automata need to respect, and investigate certain criteria of `simplicity' of the endomorphism monoid, for each of them. In the case of countable subshifts, we concentrate on countable so c shifts, that is, countable subshifts de ned by a nite state automaton. We develop some general tools for studying cellular automata on such subshifts, and show that nilpotency and periodicity of cellular automata are decidable properties, and positive expansivity is impossible. Nevertheless, we also prove various undecidability results, by simulating counter machines with cellular automata. We prove that minimal subshifts generated by primitive Pisot substitutions only support virtually cyclic automorphism groups, and give an example of a Toeplitz subshift whose automorphism group is not nitely generated. In the algebraic setting, we study the centralizers of CA, and group and lattice homomorphic CA. In particular, we obtain results about centralizers of symbol permutations and bipermutive CA, and their connections with group structures.

Digital Preservation Tools, Practices, and Policies in Islandora

Presentation at Open Repositories 2014, Helsinki, Finland, June 9-13, 2014

Geo-enabling repositories - techniques, tools, and challenges

Presentation at Open Repositories 2014, Helsinki, Finland, June 9-13, 2014

LVDC power distribution system: computational modelling

In the doctoral dissertation, low-voltage direct current (LVDC) distribution system stability, supply security and power quality are evaluated by computational modelling and measurements on an LVDC research platform. Computational models for the LVDC network analysis are developed. Time-domain simulation models are implemented in the time-domain simulation environment PSCAD/EMTDC. The PSCAD/EMTDC models of the LVDC network are applied to the transient behaviour and power quality studies. The LVDC network power loss model is developed in a MATLAB environment and is capable of fast estimation of the network and component power losses. The model integrates analytical equations that describe the power loss mechanism of the network components with power flow calculations. For an LVDC network research platform, a monitoring and control software solution is developed. The solution is used to deliver measurement data for verification of the developed models and analysis of the modelling results. In the work, the power loss mechanism of the LVDC network components and its main dependencies are described. Energy loss distribution of the LVDC network components is presented. Power quality measurements and current spectra are provided and harmonic pollution on the DC network is analysed. The transient behaviour of the network is verified through time-domain simulations. DC capacitor guidelines for an LVDC power distribution network are introduced. The power loss analysis results show that one of the main optimisation targets for an LVDC power distribution network should be reduction of the no-load losses and efficiency improvement of converters at partial loads. Low-frequency spectra of the network voltages and currents are shown, and harmonic propagation is analysed. Power quality in the LVDC network point of common coupling (PCC) is discussed. Power quality standard requirements are shown to be met by the LVDC network. The network behaviour during transients is analysed by time-domain simulations. The network is shown to be transient stable during large-scale disturbances. Measurement results on the LVDC research platform proving this are presented in the work.

Development of remote monitoring process tools for biomass fired bubbling fluidized bed boilers

Remote monitoring of a power boiler allows the supplying company to make sure that equipment is used as supposed to and gives a good chance for process optimization. This improves co-operation between the supplier and the customer and creates an aura of trust that helps securing future contracts. Remote monitoring is already in use with recovery boilers but the goal is to expand especially to biomass-fired BFB-boilers. To make remote monitoring possible, data has to be measured reliably on site and the link between the power plant and supplying company’s server has to work reliably. Data can be gathered either with the supplier’s sensors or with measurements originally installed in the power plant if the plant in question is not originally built by the supplying company. Main goal in remote monitoring is process optimization and avoiding unnecessary accidents. This can be achieved for instance by following the efficiency curves and fouling in different parts of the process and comparing them to past values. The final amount of calculations depends on the amount of data gathered. Sudden changes in efficiency or fouling require further notice and in such a case it’s important that dialogue toward the power plant in question also works.

Macroalgae across environmental gradients : tools for managing rocky coastal areas of the northern Baltic Sea

Macroalgae are the main primary producers of the temperate rocky shores providing a three-dimensional habitat, food and nursery grounds for many other species. During the past decades, the state of the coastal waters has deteriorated due to increasing human pressures, resulting in dramatic changes in coastal ecosystems, including macroalgal communities. To reverse the deterioration of the European seas, the EU has adopted the Water Framework Directive (WFD) and the Marine Strategy Framework Directive (MSFD), aiming at improved status of the coastal waters and the marine environment. Further, the Habitats Directive (HD) calls for the protection of important habitats and species (many of which are marine) and the Maritime Spatial Planning Directive for sustainability in the use of resources and human activities at sea and by the coasts. To efficiently protect important marine habitats and communities, we need knowledge on their spatial distribution. Ecological knowledge is also needed to assess the status of the marine areas by involving biological indicators, as required by the WFD and the MSFD; knowledge on how biota changes with human-induced pressures is essential, but to reliably assess change, we need also to know how biotic communities vary over natural environmental gradients. This is especially important in sea areas such as the Baltic Sea, where the natural environmental gradients create substantial differences in biota between areas. In this thesis, I studied the variation occurring in macroalgal communities across the environmental gradients of the northern Baltic Sea, including eutrophication induced changes. The aim was to produce knowledge to support the reliable use of macroalgae as indicators of ecological status of the marine areas and to test practical metrics that could potentially be used in status assessments. Further, the aim was to develop a methodology for mapping the HD Annex I habitat reefs, using the best available data on geology and bathymetry. The results showed that the large-scale variation in the macroalgal community composition of the northern Baltic Sea is largely driven by salinity and exposure. Exposure is important also on smaller spatial scales, affecting species occurrence, community structure and depth penetration of algae. Consequently, the natural variability complicates the use of macroalgae as indicators of human-induced changes. Of the studied indicators, the number of perennial algal species, the perennial cover, the fraction of annual algae, and the lower limit of occurrence of red and brown perennial algae showed potential as usable indicators of ecological status. However, the cumulated cover of algae, commonly used as an indicator in the fully marine environments, showed low responses to eutrophication in the area. Although the mere occurrence of perennial algae did not show clear indicator potential, a distinct discrepancy in the occurrence of bladderwrack, Fucus vesiculosus, was found between two areas with differing eutrophication history, the Bothnian Sea and the Archipelago Sea. The absence of Fucus from many potential sites in the outer Archipelago Sea is likely due to its inability to recover from its disappearance from the area 30-40 years ago, highlighting the importance of past events in macroalgal occurrence. The methodology presented for mapping the potential distribution and the ecological value of reefs showed, that relatively high accuracy in mapping can be achieved by combining existing available data, and the maps produced serve as valuable background information for more detailed surveys. Taken together, the results of the theses contribute significantly to the knowledge on macroalgal communities of the northern Baltic Sea that can be directly applied in various management contexts.

Cardiac Troponin Specific Autoantibodies: Analytical Tools for Exploring Their Impact on Cardiac Troponin I Testing

Cardiac troponin (cTn) I and T are the recommended biomarkers for the diagnosis and risk stratification of patients with suspected acute coronary syndrome (ACS), a major cause of cardiovascular death and disability worldwide. It has recently been demonstrated that cTn-specific autoantibodies (cTnAAb) can negatively interfere with cTnI detection by immunoassays to the extent that cTnAAb-positive patients may be falsely designated as cTnI-negative. The aim of this thesis was to develop and optimize immunoassays for the detection of both cTnI and cTnAAb, which would eventually enable exploring the clinical impact of these autoantibodies on cTnI testing and subsequent patient management. The extent of cTnAAb interference in different cTnI assay configurations and the molecular characteristics of cTnAAbs were investigated in publications I and II, respectively. The findings showed that cTnI midfragment targeting immunoassays used predominantly in clinical practice are affected by cTnAAb interference which can be circumvented by using a novel 3+1-type assay design with three capture antibodies against the N-terminus, midfragment and C-terminus and one tracer antibody against the C-terminus. The use of this assay configuration was further supported by the epitope specificity study, which showed that although the midfragment is most commonly targeted by cTnAAbs, the interference basically encompasses the whole molecule, and there may be remarkable individual variation at the affected sites. In publications III and IV, all the data obtained in previous studies were utilized to develop an improved version of an existing cTnAAb assay and a sensitive cTnI assay free of this specific analytical interference. The results of the thesis showed that approximately one in 10 patients with suspected ACS have detectable amounts of cTnAAbs in their circulation and that cTnAAbs can inhibit cTnI determination when targeted against the binding sites of assay antibodies used in its immunological detection. In the light of these observations, the risk of clinical misclassification caused by the presence of cTnAAbs remains a valid and reasonable concern. Because the titers, affinities and epitope specificities of cTnAAbs and the concentration of endogenous cTnI determine the final effect of circulating cTnAAbs, appropriately sized studies on their clinical significance are warranted. The new cTnI and cTnAAb assays could serve as analytical tools for establishing the impact of cTnAAbs on cTnI testing and also for unraveling the etiology of cTn-related autoimmune responses.

Computational modeling of stented coronary arteries

The application of computational fluid dynamics (CFD) and finite element analysis (FEA) has been growing rapidly in the various fields of science and technology. One of the areas of interest is in biomedical engineering. The altered hemodynamics inside the blood vessels plays a key role in the development of the arterial disease called atherosclerosis, which is the major cause of human death worldwide. Atherosclerosis is often treated with the stenting procedure to restore the normal blood flow. A stent is a tubular, flexible structure, usually made of metals, which is driven and expanded in the blocked arteries. Despite the success rate of the stenting procedure, it is often associated with the restenosis (re-narrowing of the artery) process. The presence of non-biological device in the artery causes inflammation or re-growth of atherosclerotic lesions in the treated vessels. Several factors including the design of stents, type of stent expansion, expansion pressure, morphology and composition of vessel wall influence the restenosis process. Therefore, the role of computational studies is crucial in the investigation and optimisation of the factors that influence post-stenting complications. This thesis focuses on the stent-vessel wall interactions followed by the blood flow in the post-stenting stage of stenosed human coronary artery. Hemodynamic and mechanical stresses were analysed in three separate stent-plaque-artery models. Plaque was modeled as a multi-layer (fibrous cap (FC), necrotic core (NC), and fibrosis (F)) and the arterial wall as a single layer domain. CFD/FEA simulations were performed using commercial software packages in several models mimicking the various stages and morphologies of atherosclerosis. The tissue prolapse (TP) of stented vessel wall, the distribution of von Mises stress (VMS) inside various layers of vessel wall, and the wall shear stress (WSS) along the luminal surface of the deformed vessel wall were measured and evaluated. The results revealed the role of the stenosis size, thickness of each layer of atherosclerotic wall, thickness of stent strut, pressure applied for stenosis expansion, and the flow condition in the distribution of stresses. The thicknesses of FC, and NC and the total thickness of plaque are critical in controlling the stresses inside the tissue. A small change in morphology of artery wall can significantly affect the distribution of stresses. In particular, FC is the most sensitive layer to TP and stresses, which could determine plaque’s vulnerability to rupture. The WSS is highly influenced by the deflection of artery, which in turn is dependent on the structural composition of arterial wall layers. Together with the stenosis size, their roles could play a decisive role in controlling the low values of WSS (<0.5 Pa) prone to restenosis. Moreover, the time dependent flow altered the percentage of luminal area with WSS values less than 0.5 Pa at different time instants. The non- Newtonian viscosity model of the blood properties significantly affects the prediction of WSS magnitude. The outcomes of this investigation will help to better understand the roles of the individual layers of atherosclerotic vessels and their risk to provoke restenosis at the post-stenting stage. As a consequence, the implementation of such an approach to assess the post-stented stresses will assist the engineers and clinicians in optimizing the stenting techniques to minimize the occurrence of restenosis.

Digitization Project of Kindred Languages : materials, methods and tools for researchers

Presentation at "Soome-ugri keelte andmebaasid ja e-leksikograafia" at Eesti Keele Instituut (Institution of Estonian Languages) in Tallnn on the 18th of November 2014.