Broadband excitation in the system identification of active magnetic bearing rotor systems

One of the targets of the climate and energy package of the European Union is to increase the energy efficiency in order to achieve a 20 percent reduction in primary energy use compared with the projected level by 2020. The energy efficiency can be improved for example by increasing the rotational speed of large electrical drives, because this enables the elimination of gearboxes leading to a compact design with lower losses. The rotational speeds of traditional bearings, such as roller bearings, are limited by mechanical friction. Active magnetic bearings (AMBs), on the other hand, allow very high rotational speeds. Consequently, their use in large medium- and high-speed machines has rapidly increased. An active magnetic bearing rotor system is an inherently unstable, nonlinear multiple-input, multiple-output system. Model-based controller design of AMBs requires an accurate system model. Finite element modeling (FEM) together with the experimental modal analysis provides a very accurate model for the rotor, and a linearized model of the magneticactuators has proven to work well in normal conditions. However, the overall system may suffer from unmodeled dynamics, such as dynamics of foundation or shrink fits. This dynamics can be modeled by system identification. System identification can also be used for on-line diagnostics. In this study, broadband excitation signals are adopted to the identification of an active magnetic bearing rotor system. The broadband excitation enables faster frequency response function measurements when compared with the widely used stepped sine and swept sine excitations. Different broadband excitations are reviewed, and the random phase multisine excitation is chosen for further study. The measurement times using the multisine excitation and the stepped sine excitation are compared. An excitation signal design with an analysis of the harmonics produced by the nonlinear system is presented. The suitability of different frequency response function estimators for an AMB rotor system are also compared. Additionally, analytical modeling of an AMB rotor system, obtaining a parametric model from the nonparametric frequency response functions, and model updating are discussed in brief, as they are key elements in the modeling for a control design. Theoretical methods are tested with a laboratory test rig. The results conclude that an appropriately designed random phase multisine excitation is suitable for the identification of AMB rotor systems.

Rural Food System Change in Tanzania during the Post-Ujamaa Era. A Case Study from Western Bagamoyo District

Food systems in Sub-Saharan Africa have been rapidly transforming during the recent decades with diverse outcomes on human development and environment. This study explores the food system change in rural villages in eastern Tanzania where subsistence agriculture has traditionally been the main source of livelihood. The focus is on the salient changes in the spatial dimensions and structural composition of the food system in the context of economic liberalization that has taken place after the end of the socialist ujamaa era in the mid-1980s. In addition, the linkages of the changes are examined in relation to food security, socio-economic situation, livelihoods, and local environment. The approach of the study is geographical, but also involves various multi-disciplinary elements, particularly from development studies. The research methods included thematic and questionnaire interviews, participatory tools, and the analysis of land use/ cover data and official documents. Several earlier studies that were made in the area during the late 1970s and 1980s provided an important reference base. The study shows that subsistence farming has lost its dominant role in food provisioning due to the declining productivity of land, livestock losses, and the increasing shift of labour to non-farm sectors. Also rapid population growth has added to the pressure on land and other natural resources. Despite the increasing need for money for buying marketed foods and other necessities, the nutritional situation shows improvement and severe malnutrition has diminished. However, the long-term sustainability of this transformation raises concerns. Firstly, the food security situation continues to be fragile and prone to shocks such as adverse climatic conditions, crop failures and price hikes. Secondly, the commodification of the food system and livelihoods in general is linked to rapid environmental degradation in the area, particularly the loss of soil fertility and deforestation. The situation calls for efforts that take more determined and holistic approaches towards sustainable development of the rural food system with particular focus on the role and viability of small-scale farming.

The strategic use of military contractors : American commercial military service providers in Bosnia and Liberia, 1995-2009

Drawing from strategic theory, this study investigates the strategic roles of commercial companies providing military services, frequently referred to as private military companies. Theoretically, the thesis analyzes how states organize its military capabilities in order to be able to wield power within the international system while empirically, it examines the character and role of commercial companies that provide military training services to the United States Government and partner nations. The reason for this rather instrumental and functional, rather than critical, approach is that this work is written within the discipline known as War Studies. Strategic theory is used first to logically organize the empirical findings in two case studies and then to develop an analytical framework with which the strategic roles of companies providing military services can be investigated. The analysis has been conducted using both new and hitherto unknown sources in the shape of interviews as well as previously classified telegrams, but also draws on previous research and other secondary sources. The main findings are that commercial companies have five typical strategic roles: first, they cloak the state by substituting traditional uniformed troops; second, they act as trailblazers by securing US influence in new regions and by breaking new ground by contributing to the build-up of new partners; third, they act as scene setters by preparing the ground for military exit out of a theater of operations or by facilitating inter-operability between foreign militaries and the US military; fourth, they can be used to infiltrate the security structures of foreign countries; fifth and finally, they can be used to provide offensive capabilities by providing either kinetic or cyber warfare effects. Another finding is that military service contracting is an important part of the US strategic culture.

Development of a measuring-control system for energy monitoring in low power

In this thesis a control system for an intelligent low voltage energy grid is presented, focusing on the control system created by using a multi-agent approach which makes it versatile and easy to expand according to the future needs. The control system is capable of forecasting the future energy consumption and decisions making on its own without human interaction when countering problems. The control system is a part of the St. Petersburg State Polytechnic University’s smart grid project that aims to create a smart grid for the university’s own use. The concept of the smart grid is interesting also for the consumers as it brings new possibilities to control own energy consumption and to save money. Smart grids makes it possible to monitor the energy consumption in real-time and to change own habits to save money. The intelligent grid also brings possibilities to integrate the renewable energy sources to the global or the local energy production much better than the current systems. Consumers can also sell their extra power to the global grid if they want.

Building object-oriented software with the D-Bus messaging system

Object-oriented programming is a widely adopted paradigm for desktop software development. This paradigm partitions software into separate entities, objects, which consist of data and related procedures used to modify and inspect it. The paradigm has evolved during the last few decades to emphasize decoupling between object implementations, via means such as explicit interface inheritance and event-based implicit invocation. Inter-process communication (IPC) technologies allow applications to interact with each other. This enables making software distributed across multiple processes, resulting in a modular architecture with benefits in resource sharing, robustness, code reuse and security. The support for object-oriented programming concepts varies between IPC systems. This thesis is focused on the D-Bus system, which has recently gained a lot of users, but is still scantily researched. D-Bus has support for asynchronous remote procedure calls with return values and a content-based publish/subscribe event delivery mechanism. In this thesis, several patterns for method invocation in D-Bus and similar systems are compared. The patterns that simulate synchronous local calls are shown to be dangerous. Later, we present a state-caching proxy construct, which avoids the complexity of properly asynchronous calls for object inspection. The proxy and certain supplementary constructs are presented conceptually as generic object-oriented design patterns. The e ect of these patterns on non-functional qualities of software, such as complexity, performance and power consumption, is reasoned about based on the properties of the D-Bus system. The use of the patterns reduces complexity, but maintains the other qualities at a good level. Finally, we present currently existing means of specifying D-Bus object interfaces for the purposes of code and documentation generation. The interface description language used by the Telepathy modular IM/VoIP framework is found to be an useful extension of the basic D-Bus introspection format.

Battery Cell Modeling for Battery Management System

Usage of batteries as energy storage is emerging in automotive and mobile working machine applications in future. When battery systems become larger, battery management becomes an essential part of the application concerning fault situations of the battery and safety of the user. A properly designed battery management system extends one charge cycle of battery pack and the whole life time of the battery pack. In this thesis main objectives and principles of BMS are studied and first order Thevenin’s model of the lithium-titanate battery cell is built based on laboratory measurements. The battery cell model is then verified by comparing the battery cell model and the actual battery cell and its suitability for use in BMS is studied.

Identification and characterisation of a novel adhesin of Streptococcus suis and its use as a target of adhesion inhibition and bacterial detection

Streptococcus suis is an important pig pathogen but it is also zoonotic, i.e. capable of causing diseases in humans. Human S. suis infections are quite uncommon but potentially life-threatening and the pathogen is an emerging public health concern. This Gram-positive bacterium possesses a galabiose-specific (Galalpha1−4Gal) adhesion activity, which has been studied for over 20 years. P-fimbriated Escherichia coli−bacteria also possess a similar adhesin activity targeting the same disaccharide. The galabiose-specific adhesin of S. suis was identified by an affinity proteomics method. No function of the protein identified was formerly known and it was designated streptococcal adhesin P (SadP). The peptide sequence of SadP contains an LPXTG-motif and the protein was proven to be cell wall−anchored. SadP may be multimeric since in SDS-PAGE gel it formed a protein ladder starting from about 200 kDa. The identification was confirmed by producing knockout strains lacking functional adhesin, which had lost their ability to bind to galabiose. The adhesin gene was cloned in a bacterial expression host and properties of the recombinant adhesin were studied. The galabiose-binding properties of the recombinant protein were found to be consistent with previous results obtained studying whole bacterial cells. A live-bacteria application of surface plasmon resonance was set up, and various carbohydrate inhibitors of the galabiose-specific adhesins were studied with this assay. The potencies of the inhibitors were highly dependent on multivalency. Compared with P-fimbriated E. coli, lower concentrations of galabiose derivatives were needed to inhibit the adhesion of S. suis. Multivalent inhibitors of S. suis adhesion were found to be effective at low nanomolar concentrations. To specifically detect galabiose adhesin−expressing S. suis bacteria, a technique utilising magnetic glycoparticles and an ATP bioluminescence bacterial detection system was also developed. The identification and characterisation of the SadP adhesin give valuable information on the adhesion mechanisms of S. suis, and the results of this study may be helpful for the development of novel inhibitors and specific detection methods of this pathogen.

Dispersal and metacommunity dynamics in a soft-sediment benthic system : how well is the seafloor connected?

Connectivity depends on rates of dispersal between communities. For marine soft-sediment communities continued small-scale dispersal as post-larvae and as adults can be equally important in maintaining community composition, as initial recruitment of substrate by pelagic larvae. In this thesis post-larval dispersal strategies of benthic invertebrates, as well as mechanisms by which communities are connected were investigated. Such knowledge on dispersal is scarce, due to the difficulties in actually measuring dispersal directly in nature, and dispersal has not previously been quantified in the Baltic Sea. Different trap-types were used underwater to capture dispersing invertebrates at different sites, while in parallel measuring waves and currents. Local community composition was found to change predictably under varying rates of dispersal and physical connectivity (waves and currents). This response was, however, dependent on dispersal-related traits of taxa. Actively dispersing taxa will be relatively better at maintaining their position, as they are not as dependent on hydrodynamic conditions for dispersal and will be less prone to be passively transported by currents. Taxa also dispersed in relative proportions that were distinctly different from resident community composition and a significant proportion (40 %) of taxa were found to lack a planktonic larval life-stage. Community assembly was re-started in a large-scale manipulative field experiment over one year across several sites, which revealed how patterns of community composition (α-, β- and λ-diversity) change depending on rates of dispersal. Results also demonstrated that in response to small-scale disturbance, initial recruitment was by nearby-dominant species after which other species arrived from successively further away. At later assembly time, the number of coexisting species increased beyond what was expected purely by local niche requirements (species sorting), transferring regional differences in community composition (β-diversity) to the local scale (α-diversity, mass effect). Findings of this thesis complement more theoretical studies in metacommunity ecology by demonstrating that understanding how and when individuals disperse relative to underlying environmental heterogeneity is key to interpreting how patterns of diversity change across different spatial scales. Such information from nature is critical when predicting responses to, for example, different types of disturbances or management actions in conservation.

Improving alumni administration by self-built information system : building IMMIT connected' to enhance alumni connection

Alumni are considered as precious resource of the institutions, thus improving alumni adminis-tration is critical. In information era, alumni administration is assisted by widespread information technology, such as social network sites. This paper aims to discover if a self-built information sys-tem would enhance alumni connection in the IMMIT context, and what kind of attributes would be helpful applying to the special context. The current online alumni services at other universities and at the IMMIT host university are analyzed, and then social media is introduced. After illustrating the social capital existing in IM-MIT, the type of the self-built information system is suggested, following an interpretation of the prototype. Two research models are utilized in this article: TAM and intentional social action model. The second model is adjusted with proposed parameters. Afterwards, a survey and an interview protocol are designed under the guidance of the models. The results are analyzed in several groups, and the proposed parameters are tested. A conclusion is drawn to indicate how to improve alumni‟s intention to use and how to achieve a better-accepted design.

Secure Bluetooth Audio Transmission System

The growing spread of small but powerful mobile devices (such as PDAs, mobile phone, Internet Tablet, etc.) opens up new scenarios in which users can interact with such devices in many environments in order to access the information at different locations. In this thesis, a ubiquitous computing based system called Secure Bluetooth Audio Transmission System is introduced. This system is situated in a large public place (like airport, festival venues, etc.), where voice messages are conveyed from the system to users' Bluetooth headsets in order to inform users the latest flight schedule and other public information. The reliability of the message is secured by adopting an authorization strategy and ECDSA. In order to assess and evaluate the risks and potential weaknesses of the system, an easy-to-use prototype implementation was written and tested. Other possible uses and further research were also considered.

Tertiary Treatment and Re-use of Kraft Pulp Mill Effluent

The efficient use of materials and natural recourses, for ecological and economic reasons, has become more and more important in all industries. In the forest industries this means higher levels of closure in the material circulations of the mills. One possibility to reduce wastewater discharge is to re-use part of the 2nd clarifier effluent as process water. The main target of this thesis was to evaluate the technical suitability of several mechanical and chemical tertiary treatment methods for water re-use. Some of the tested methods seemed to have high potential for the removal of some specific constituents from the wastewater. Tertiary treatment is needed because higher levels of closure may cause problems with increasing amounts of non-process elements in different points of kraft pulp process. The aspect of sustainable development was taken into account by evaluating positive and negative environmental effects of the treatment processes. Environmental benefits can be gained by using some of the tertiary treatment methods tested. These methods should still be researched more for system optimization.

Effects of anthropogenic and natural hydrological changes on the behavior of the acidic metal discharge from acid sulfate soils in a river- and lake system in western Finland

Larsmo-Öjasjön i Österbotten skapades genom invallningar på 1960-talet pga. industrins behov av sötvatten. Sedan dess har vattenområdet drabbats av återkommande försurning och fiskdöd, och invallningen har ofta beskyllts för problemen. Avhandlingen undersöker syrabelastningen i området; bl.a. hur markanvändning, hydrologi och klimatförändringen påverkar belastningen. Konsekvenserna undersöks med fiskyngel som bioindikator, och olika miljömetoder testas och diskuteras. Ökad kunskap om försurningen hjälper oss att tillämpa effektiva miljömetoder och få förbättrad vattenkvalitet i framtiden. Den primära orsaken till den försämrade vattenkvaliteten under de senaste 40 åren är intensiv dikning av svavelrika sediment. Detta leder till oxidering av svavlet till svavelsyra och uppkomst av sura sulfatjordar. Syran löser upp mängder med toxiska metaller som spolas ut i vattendragen. Undersökningen visar att tiotusentals ton svavelsyra tillsammans med stora mängder metaller rinner till Larsmo-Öjasjön per år från sura sulfatjordar. Åarna bidrar med mest belastning, men den sammanlagda belastningen från de otaliga dikena och bäckarna är oväntat stor. Andra potentiella källor till försurningen, t.ex. muddringar och humussyror, beräknas vara obetydliga. Syra- och metallbelastningen varierar kraftigt med hydrologin, dvs. störst belastning sker under vår- och höstflöden. En eventuell klimatförändring kan ändra på avrinningsmönstret och orsaka mera belastning vintertid. Den årligt återkommande syra- och metallbelastningen kan ofta hindra lakens förökning, vilket kan ha större långtgående konsekvenser för fiskpopulationerna än de relativt sällsynta stora surchockerna med synlig fiskdöd. För att förebygga skador på vattendragen bör man undvika att dränera svavelrika sedimenten. På redan existerande sura sulfatjordar visade sig kontroll av grundvattennivån kunna möjliggöra en effektiverad markanvändning utan märkbart ökade miljökonsekvenser.

Variable speed drive in fan system monitoring

Fan systems are responsible for approximately 10% of the electricity consumption in industrial and municipal sectors, and it has been found that there is energy-saving potential in these systems. To this end, variable speed drives (VSDs) are used to enhance the efficiency of fan systems. Usually, fan system operation is optimized based on measurements of the system, but there are seldom readily installed meters in the system that can be used for the purpose. Thus, sensorless methods are needed for the optimization of fan system operation. In this thesis, methods for the fan operating point estimation with a variable speed drive are studied and discussed. These methods can be used for the energy efficient control of the fan system without additional measurements. The operation of these methods is validated by laboratory measurements and data from an industrial fan system. In addition to their energy consumption, condition monitoring of fan systems is a key issue as fans are an integral part of various production processes. Fan system condition monitoring is usually carried out with vibration measurements, which again increase the system complexity. However, variable speed drives can already be used for pumping system condition monitoring. Therefore, it would add to the usability of a variablespeed- driven fan system if the variable speed drive could be used as a condition monitoring device. In this thesis, sensorless detection methods for three lifetime-reducing phenomena are suggested: these are detection of the fan contamination build-up, the correct rotational direction, and the fan surge. The methods use the variable speed drive monitoring and control options for the detection along with simple signal processing methods, such as power spectrum density estimates. The methods have been validated by laboratory measurements. The key finding of this doctoral thesis is that a variable speed drive can be used on its own as a monitoring and control device for the fan system energy efficiency, and it can also be used in the detection of certain lifetime-reducing phenomena.

Comparison between dSPACE and NI systems based on real-time intelligent control of a teleoperated hydraulic servo system

The Laboratory of Intelligent Machine researches and develops energy-efficient power transmissions and automation for mobile construction machines and industrial processes. The laboratory's particular areas of expertise include mechatronic machine design using virtual technologies and simulators and demanding industrial robotics. The laboratory has collaborated extensively with industrial actors and it has participated in significant international research projects, particularly in the field of robotics. For years, dSPACE tools were the lonely hardware which was used in the lab to develop different control algorithms in real-time. dSPACE's hardware systems are in widespread use in the automotive industry and are also employed in drives, aerospace, and industrial automation. But new competitors are developing new sophisticated systems and their features convinced the laboratory to test new products. One of these competitors is National Instrument (NI). In order to get to know the specifications and capabilities of NI tools, an agreement was made to test a NI evolutionary system. This system is used to control a 1-D hydraulic slider. The objective of this research project is to develop a control scheme for the teleoperation of a hydraulically driven manipulator, and to implement a control algorithm between human and machine interaction, and machine and task environment interaction both on NI and dSPACE systems simultaneously and to compare the results.

PDM system functions and utilizations analysis to improve efficiency of sheet metal product design and manufacturing

This study will concentrate on Product Data Management (PDM) systems, and sheet metal design features and classification. In this thesis, PDM is seen as an individual system which handles all product-related data and information. The meaning of relevant data is to take the manufacturing process further with fewer errors. The features of sheet metals are giving more information and value to the designed models. The possibility of implementing PDM and sheet metal features recognition are the core of this study. Their integration should make the design process faster and manufacturing-friendly products easier to design. The triangulation method is the basis for this research. The sections of this triangle are: scientific literature review, interview using the Delphi method and the author’s experience and observations. The main key findings of this study are: (1) the area of focus in triangle (the triangle of three different point of views: business, information exchange and technical) depends on the person’s background and their role in the company, (2) the classification in the PDM system (and also in the CAD system) should be done using the materials, tools and machines that are in use in the company and (3) the design process has to be more effective because of the increase of industrial production, sheet metal blank production and the designer’s time spent on actual design and (4) because Design For Manufacture (DFM) integration can be done with CAD-programs, DFM integration with the PDM system should also be possible.