Software for design of experiments and response modelling of cake filtration applications

Filtration is a widely used unit operation in chemical engineering. The huge variation in the properties of materials to be ltered makes the study of ltration a challenging task. One of the objectives of this thesis was to show that conventional ltration theories are di cult to use when the system to be modelled contains all of the stages and features that are present in a complete solid/liquid separation process. Furthermore, most of the ltration theories require experimental work to be performed in order to obtain critical parameters required by the theoretical models. Creating a good overall understanding of how the variables a ect the nal product in ltration is somewhat impossible on a purely theoretical basis. The complexity of solid/liquid separation processes require experimental work and when tests are needed, it is advisable to use experimental design techniques so that the goals can be achieved. The statistical design of experiments provides the necessary tools for recognising the e ects of variables. It also helps to perform experimental work more economically. Design of experiments is a prerequisite for creating empirical models that can describe how the measured response is related to the changes in the values of the variable. A software package was developed that provides a ltration practitioner with experimental designs and calculates the parameters for linear regression models, along with the graphical representation of the responses. The developed software consists of two software modules. These modules are LTDoE and LTRead. The LTDoE module is used to create experimental designs for di erent lter types. The lter types considered in the software are automatic vertical pressure lter, double-sided vertical pressure lter, horizontal membrane lter press, vacuum belt lter and ceramic capillary action disc lter. It is also possible to create experimental designs for those cases where the variables are totally user de ned, say for a customized ltration cycle or di erent piece of equipment. The LTRead-module is used to read the experimental data gathered from the experiments, to analyse the data and to create models for each of the measured responses. Introducing the structure of the software more in detail and showing some of the practical applications is the main part of this thesis. This approach to the study of cake ltration processes, as presented in this thesis, has been shown to have good practical value when making ltration tests.

Design and characterization of large area position sensitive radiation detectors

Planar, large area, position sensitive silicon detectors are widely utilized in high energy physics research and in medical, computed tomography (CT). This thesis describes author's research work relating to development of such detector components. The key motivation and objective for the research work has been the development of novel, position sensitive detectors improving the performance of the instruments they are intended for. Silicon strip detectors are the key components of barrel-shaped tracking instruments which are typically the innermost structures of high energy physics experimental stations. Particle colliders such as the former LEP collider or present LHC produce particle collisions and the silicon strip detector based trackers locate the trajectories of particles emanating from such collisions. Medical CT has become a regular part of everyday medical care in all developed countries. CT scanning enables x-ray imaging of all parts of the human body with an outstanding structural resolution and contrast. Brain, chest and abdomen slice images with a resolution of 0.5 mm are possible and latest CT machines are able to image whole human heart between heart beats. The two application areas are presented shortly and the radiation detection properties of planar silicon detectors are discussed. Fabrication methods and preamplifier electronics of the planar detectors are presented. Designs of the developed, large area silicon detectors are presented and measurement results of the key operating parameters are discussed. Static and dynamic performance of the developed silicon strip detectors are shown to be very satisfactory for experimental physics applications. Results relating to the developed, novel CT detector chips are found to be very promising for further development and all key performance goals are met.

Puuelementtien teollisen tuotannon kehittäminen

Tavoitteena tässä diplomityössä oli selvittää puuelementtien teollisen tuotannon mahdollisuuksia ja kehityksen tilaa. Millaiset valmiudet puuelementtien valmistajilla on valmistaa rakennuttajien ja rakentajien edellyttämiä suur- ja tilaelementtejä puukerrostaloja varten, millaista tuotekehitystä ja tuotantoinvestointeja tarvitaan kaiken tämän mahdollistamiseksi, mikä on yritysten halukkuus ja resurssit investoida uuteen teknologiaan sekä kuinka voidaan parantaa tuotannon tehokkuutta. Ensin diplomityössä luotiin katsaus puukerrostalorakentamisen historiaan, nykytilaan, kerrostalojärjestelmiin, palomääräyksiin ja ruotsalaiseen puuelementtien valmistamisen kehityksen tilaan. Puuelementtien valmistukseen tutustumisen jälkeen laadittiin kyselylomake tutkimusta varten, joka lähettiin 64:lle puuelementtien valmistajalle. Tutkimukseen vastasi kaikkiaan 20 puuelementtien valmistajaa. Vastausprosentiksi muodostui 31 %. Tutkimuksen perusteella voidaan todeta puuelementtien valmistajien olevan pieniä ja keskisuuria pk-yrityksiä jotka valmistavat puuelementtejä pääasiassa pientaloteollisuudelle. Suomalaisten valmistajien automaation taso ja tekninen osaaminen ei juuri eroa ruotsalaisesta puuelementtien valmistuksesta. Suomessa puuelementtien valmistus puukerrostaloja varten ei ole vielä vakiintunutta samalla tavalla kuten Ruotsissa. Suomessa Puukerrostalokohteita lähtee liikkeelle tällä hetkellä vielä aivan liian vähän. Kilpailukyky ja tehokkuus tulevat kehittymään nopeasti kun teollinen valmistus saadaan riittävän korkealle tasolle.

Foot Health In Older People - Development of a preventive, evaluative instrument for nurses

Foot health is a part of overall health in every age group and its importance increases during ageing. Health care professionals are in a vital position for preventing foot health problems, and identifying and caring them in older people. Despite the rather high number of studies conducted in the field of foot health in older people, reliable and valid nurse-administered foot health assessment instruments seem to be lacking. By identifying foot health in older people, it is possible to develop nursing interventions to enhance safe, independent living at home. The purpose of this three-phase study was to develop an instrument to assess the level of foot health in older people and evaluate foot care practices from the perspective of older people themselves and nurses in home care. The ultimate goal is to prevent foot health problems by increasing the attention paid to older people’s feet and recognizing those foot health problems which need further care; thus not focus on different foot health problems. The study was conducted in different phases and contexts. In phase 1, a descriptive design with a literature review from the Medline (R) and CINAHL databases to explore foot health in older people and nurses’ role in foot health care and pre-post design intervention study in nursing home with nursing staff (n=16) and older residents (n=43) were conducted. In phase 2, a descriptive and explorative study design was employed to develop an instrument for assessing foot health in older people (N=651, n=309, response rate 47%) and explore the psychometrics of the instrument. The data were collected from sheltered housing and home care settings. Finally, in phase 3, descriptive and explorative as well as cross-sectional correlational survey designs were used to assess foot health and evaluate the foot self-care activities of older people (N=651, n=309, response rate 47%) and to describe foot care knowledge and caring activities of nurses (N=651, n=322, response rate 50%) in home care in Finland. To achieve this, the Foot Health Assessment Instrument (FHAI) developed in phase 2 was used; at the same time, this large sample also was used for the psychometric evaluation of the FHAI. The data analysis methods used in this study were content analysis, descriptive and inferential statistics including factor and multivariate analysis. Many long-term diseases can manifest in feet. Therefore, the FHAI, developed in this study consisted of items relating to skin and nail health, foot structure and foot pain. The FHAI demonstrated acceptable preliminary psychometric properties. A great deal of different foot health problems in older people were found of which edema, dry skin, thickened and discoloured toenails and hallux valgus were the most prevalent foot health problems. Moreover, many older people had difficulties in performing foot self-care. Nurses’ knowledge of foot care was insufficient and revealed a need for more information and continuing education in matters relating to foot care in older people. Instead, nurses’ foot care activities were mainly adequate, though the findings indicate the need for updating foot care activities to correspond with the evidence found in the field of foot care. Practical implications are presented for nursing practice, education and administration. In future, research should focus on developing interventions for older people and nurses to promote foot health in older people and to prevent foot health problems, as well as for further development of the FHAI.

Adaptive Routing Approaches for Networked Many-Core Systems

Through advances in technology, System-on-Chip design is moving towards integrating tens to hundreds of intellectual property blocks into a single chip. In such a many-core system, on-chip communication becomes a performance bottleneck for high performance designs. Network-on-Chip (NoC) has emerged as a viable solution for the communication challenges in highly complex chips. The NoC architecture paradigm, based on a modular packet-switched mechanism, can address many of the on-chip communication challenges such as wiring complexity, communication latency, and bandwidth. Furthermore, the combined benefits of 3D IC and NoC schemes provide the possibility of designing a high performance system in a limited chip area. The major advantages of 3D NoCs are the considerable reductions in average latency and power consumption. There are several factors degrading the performance of NoCs. In this thesis, we investigate three main performance-limiting factors: network congestion, faults, and the lack of efficient multicast support. We address these issues by the means of routing algorithms. Congestion of data packets may lead to increased network latency and power consumption. Thus, we propose three different approaches for alleviating such congestion in the network. The first approach is based on measuring the congestion information in different regions of the network, distributing the information over the network, and utilizing this information when making a routing decision. The second approach employs a learning method to dynamically find the less congested routes according to the underlying traffic. The third approach is based on a fuzzy-logic technique to perform better routing decisions when traffic information of different routes is available. Faults affect performance significantly, as then packets should take longer paths in order to be routed around the faults, which in turn increases congestion around the faulty regions. We propose four methods to tolerate faults at the link and switch level by using only the shortest paths as long as such path exists. The unique characteristic among these methods is the toleration of faults while also maintaining the performance of NoCs. To the best of our knowledge, these algorithms are the first approaches to bypassing faults prior to reaching them while avoiding unnecessary misrouting of packets. Current implementations of multicast communication result in a significant performance loss for unicast traffic. This is due to the fact that the routing rules of multicast packets limit the adaptivity of unicast packets. We present an approach in which both unicast and multicast packets can be efficiently routed within the network. While suggesting a more efficient multicast support, the proposed approach does not affect the performance of unicast routing at all. In addition, in order to reduce the overall path length of multicast packets, we present several partitioning methods along with their analytical models for latency measurement. This approach is discussed in the context of 3D mesh networks.

Model-View-Controller architectural pattern and its evolution in graphical user interface frameworks

Model-View-Controller (MVC) is an architectural pattern used in software development for graphical user interfaces. It was one of the first proposed solutions in the late 1970s to the Smart UI anti-pattern, which refers to the act of writing all domain logic into a user interface. The original MVC pattern has since evolved in multiple directions, with various names and may confuse many. The goal of this thesis is to present the origin of the MVC pattern and how it has changed over time. Software architecture in general and the MVC’s evolution within web applications are not the primary focus. Fundamen- tal designs are abstracted, and then used to examine the more recent versions. Prob- lems with the subject and its terminology are also presented.

“Valley co-creation” – exploring the emergence of a cultural product in an entrepreneur-driven value network: Case study: Black Weekend festival

The interconnected domains are attracting interest from industries and academia, although this phenomenon, called ‘convergence’ is not new. Organizational research has indeed focused on uncovering co-creation for manufacturing and the industrial organization, with limited implications to entrepreneurship. Although convergence has been characterized as a process connecting seemingly disparate disciplines, it is argued that these studies tend to leave the creative industries unnoticed. With the art market boom and new forms of collaboration riding past the institution-focused arts marketing literature, this thesis takes a leap to uncover the processes of entrepreneurship in the emergence of a cultural product. As a symbolic work of synergism itself, the thesis combines organizational theory with literature in natural sciences and arts. Assuming nonlinearity, a framework is created for analysing aesthetic experience in an empirical event where network actors are connected to multiple contexts. As the focal case in study, the empirical analysis performed for a music festival organized in a skiing resort in the French Alps in March. The researcher attends the festival and models its cocreation process by enquiring from an artist, festival organisers, and a festival visitor. The findings contribute to fields of entrepreneurship, aesthetics and marketing mainly. It is found that the network actors engage in intimate and creative interaction where activity patterns are interrupted and cultural elements combined. This process is considered to both create and destruct value, through identity building, legitimisation, learning, and access to larger audiences, and it is considered particularly useful for domains where resources are too restrained for conventional marketing practices. This thesis uncovered the role of artists and informants and posits that particularly through experience design, this type of skilled individual be regarded more often as a research informant. Future research is encouraged to engage in convergence by experimenting with different fields and research designs, and it is suggested that future studies could arrive at different descriptive results.

Licensing Model Development for Small Modular Reactors (SMRs) - Focusing on the Finnish Regulatory Framework

Recently, Small Modular Reactors (SMRs) have attracted increased public discussion. While large nuclear power plant new build projects are facing challenges, the focus of attention is turning to small modular reactors. One particular project challenge arises in the area of nuclear licensing, which plays a significant role in new build projects affecting their quality as well as costs and schedules. This dissertation - positioned in the field of nuclear engineering but also with a significant section in the field of systems engineering - examines the nuclear licensing processes and their suitability for the characteristics of SMRs. The study investigates the licensing processes in selected countries, as well as other safety critical industry fields. Viewing the licensing processes and their separate licensing steps in terms of SMRs, the study adopts two different analysis theories for review and comparison. The primary data consists of a literature review, semi-structured interviews, and questionnaire responses concerning licensing processes and practices. The result of the study is a recommendation for a new, optimized licensing process for SMRs. The most important SMR-specific feature, in terms of licensing, is the modularity of the design. Here the modularity indicates multi-module SMR designs, which creates new challenges in the licensing process. As this study focuses on Finland, the main features of the new licensing process are adapted to the current Finnish licensing process, aiming to achieve the main benefits with minimal modifications to the current process. The application of the new licensing process is developed using Systems Engineering, Requirements Management, and Project Management practices and tools. Nuclear licensing includes a large amount of data and documentation which needs to be managed in a suitable manner throughout the new build project and then during the whole life cycle of the nuclear power plant. To enable a smooth licensing process and therefore ensure the success of the new build nuclear power plant project, management processes and practices play a significant role. This study contributes to the theoretical understanding of how licensing processes are structured and how they are put into action in practice. The findings clarify the suitability of different licensing processes and their selected licensing steps for SMR licensing. The results combine the most suitable licensing steps into a new licensing process for SMRs. The results are also extended to the concept of licensing management practices and tools.

Wind tunnel simulation of atmospheric boundary layer flows

The present work shows how thick boundary layers can be produced in a short wind tunnel with a view to simulate atmospheric flows. Several types of thickening devices are analysed. The experimental assessment of the devices was conducted by considering integral properties of the flow and the spectra: skin-friction, mean velocity profiles in inner and outer co-ordinates and longitudinal turbulence. Designs based on screens, elliptic wedge generators, and cylindrical rod generators are analysed. The paper describes in detail the experimental arrangement, including the features of the wind tunnel and of the instrumentation. The results are compared with experimental data published by other authors and with naturally developed flows.

Design Space Exploration for MPSoC Architectures

Multiprocessor system-on-chip (MPSoC) designs utilize the available technology and communication architectures to meet the requirements of the upcoming applications. In MPSoC, the communication platform is both the key enabler, as well as the key differentiator for realizing efficient MPSoCs. It provides product differentiation to meet a diverse, multi-dimensional set of design constraints, including performance, power, energy, reconfigurability, scalability, cost, reliability and time-to-market. The communication resources of a single interconnection platform cannot be fully utilized by all kind of applications, such as the availability of higher communication bandwidth for computation but not data intensive applications is often unfeasible in the practical implementation. This thesis aims to perform the architecture-level design space exploration towards efficient and scalable resource utilization for MPSoC communication architecture. In order to meet the performance requirements within the design constraints, careful selection of MPSoC communication platform, resource aware partitioning and mapping of the application play important role. To enhance the utilization of communication resources, variety of techniques such as resource sharing, multicast to avoid re-transmission of identical data, and adaptive routing can be used. For implementation, these techniques should be customized according to the platform architecture. To address the resource utilization of MPSoC communication platforms, variety of architectures with different design parameters and performance levels, namely Segmented bus (SegBus), Network-on-Chip (NoC) and Three-Dimensional NoC (3D-NoC), are selected. Average packet latency and power consumption are the evaluation parameters for the proposed techniques. In conventional computing architectures, fault on a component makes the connected fault-free components inoperative. Resource sharing approach can utilize the fault-free components to retain the system performance by reducing the impact of faults. Design space exploration also guides to narrow down the selection of MPSoC architecture, which can meet the performance requirements with design constraints.

Coercion, Perceived Care and Quality of Life Among Patients in Psychiatric Hospitals

The goals of the study were to describe patients’ perceptions of care after experiencing seclusion/restraint and their quality of life. The goal was moreover to identify methodological challenges related to studies from the perspective of coerced patients. The study was conducted in three phases between September 2008 and April 2012. In the first phase, the instrument Secluded/ Restrained Patients’ Perception of their Treatment (SR-PPT) was developed and validated in Japan in cooperation with a Finnish research group (n = 56). Additional data were collected over one year from secluded/restrained patients using the instrument (n = 90). In the second phase, data were collected during the discharge process (n = 264). In the third phase, data were collected from electronic databases. Methodological and ethical issues were reviewed (n = 32) using systematic review method. Patients perceived that co-operation with the staff was poor; patients’ opinions were not taken into account, treatment targets collated and treatment methods were seen in different ways. Patients also felt that their concerns were not well enough understood. However, patients received getting nurses’ time. In particular, seclusion/restraint was considered unnecessary. The patients felt that they benefited from the isolation in treating their problems more than they needed it, even if the benefit was seen to be minor. Patients treated on forensic wards rated their treatment and care significantly lower than in general units. During hospitalization secluded/restrained patients evaluated their quality of life, however, better than did non-secluded/restrained patients. However, no conclusion is drawn to the effect that the better quality of life assessment is attributable to the seclusion/restraint because patients’ treatment period after the isolation was long and because of many other factors, as rehabilitation, medication, diagnostic differences, and adaptation. According to the systematic mixed studies review variation between study designs was found to be a methodological challenge. This makes comparison of the results more difficult. A research ethical weakness is conceded as regards descriptions of the ethical review process (44 %) and informed consent (32 %). It can be concluded that patients in psychiatric hospital care and having a voice as an equal expert require special attention to clinical nursing, decision-making and service planning. Patients and their family members will be consulted in plans of preventive and alternative methods for seclusion and restraint. The study supports the theory that in ethical decision-making situations account should be taken of medical indications, in addition to the patients’ preferences, the effect of treatment on quality of life, and this depends on other factors. The connection between treatment decisions and a patient’s quality of life should be evaluated more structurally in practice. Changing treatment culture towards patients’ involvement will support daily life in nursing and service planning taking into account improvements in patients’ quality of life.

Soraääniä, sitaatteja ja suunnitelmallisuutta. Moniäänisyys Eira Stenbergin romaanituotannossa

Tutkin väitöskirjassani Eira Stenbergin (s. 1943) romaanituotannon moniäänisyyttä, joka liittyy niin subjektiin, kertomisen prosessiin kuin todellisuuskäsityksiin. Aineistonani ovat Stenbergin 1980–1990-luvulla kirjoittamat, tutkimusongelmani kannalta keskeiseen ajanjaksoon kuuluvat romaanit Paratiisin vangit (1984), Häikäisy (1987), Kuun puutarhat (1990) sekä Gulliverin tytär (1993). 1980-luvulla postmodernista tuli kirjallisen kulttuurin keskeisimpiä aiheita Suomessa, ja subjektista tuli ongelma jopa siinä määrin että puhuttiin sen kuolemasta. Ääni oli 1980-luvulla osa subjektia koskevaa keskustelua: yhtäältä nousevan feministisen liikkeen identiteettipoliittisena ja emansipatorisena metaforana, toisaalta jälkistrukturalismin antihumanismin uhkakuvana, joka koski subjektin ääntä alkuperän lähteenä ja persoonan ilmaisuna. Äänen käsitteen voidaan katsoa implikoivan jonkinlaista käsitystä subjektista, ja tarkastelenkin tutkimuksessani erityisesti henkilöhahmoja, kertojia ja kertomisen prosessia, mutta myös tekijän suunnitelmallisuutta ja kuulijaa kohti orientoitumista. Yhdistelen tutkimuksessani retorista kertomuksen teoriaa dekonstruktioon sekä feministisiin subjektiteorioihin. Myös Mihail Bahtinin käsitys moniäänisestä romaanista on työssäni keskeinen. Problematisoin tutkimuksessani äänen kytköksen sisimmän ilmaisuun, omistamiseen ja auktoriteettiin ja ymmärrän sen keskustelualueena, jossa kohtaavat erilaiset arvot ja näkemykset maailmasta. Tällöin kaikenkattava puhe subjektin kuolemasta sekä käsitykset 1980-luvun kirjallisuudesta maailmasta vieraantuneena ja yksityisen alueelle vetäytyvänä problematisoituvat. Stenbergin tuotannon perusteella voi sanoa, että kirjallisuuden äänet saavat merkityksensä vasta erilaisina äänensävyinä konkreettisissa ja ainutkertaisissa konteksteissa. Tämä viittaa tarpeeseen ymmärtää kirjallisuusteoreettisessa keskustelussa usein historiattomana ja universaalina nähty käsite historiaan paikantuneena: eivät vain erityiset aineistot, vaan myös erityiset kontekstit määrittelevät äänen saamia merkityksiä.

Quantification and Clinical Relevance of Cystatin C

An aging population and increasing rates of diabetes mellitus contribute to a high prevalence of kidney dysfunction – approximately 10 percent of adults in developed countries have chronic kidney disease (CKD). CKD is a progressive loss of kidney function and this remains permanent. Early recognition of this condition is important for prevention or impeding severe adverse cardiac and renal outcomes. Cystatin C is a low molecular weight cysteine protease inhibitor that has emerged as a biomarker of kidney function. The special potential of plasma cystatin C in this setting is related to its independency of muscle mass, which is a remarkable limitation of the traditional marker creatinine. Cystatin C is a sensitive marker in diagnosing mild and moderate CKD, especially in small children, in the elderly and in conditions where muscle mass is affected. Cystatin C is quantified with immunoassays, mainly based on particle-enhanced nephelometry (PENIA) or turbidimetry (PETIA). The aim of this study was to develop a rapid and reliable assay for quantification of human cystatin C in plasma or serum by utilizing time-resolved fluorescence-based immunoassay methods. This was accomplished by utilizing different antibodies, including polyclonal and 7 monoclonal antibodies against cystatin C. Different assay designs were tested and the best assay was further modified to a dry-reagent double monoclonal assay run on an automated immunonalyzer. This assay was evaluated for clinical performance in estimating reduced kidney function and in predicting risk of adverse outcomes in patients with non-ST elevation acute coronary syndrome. Of the tested assay designs, heterogeneous non-competitive assay had the best performace and was chosen to be developed further. As an automated double monoclonal assay, this assay enabled a reliable measurement of clinically relevant cystatin C concentrations. It also showed a stronger concordance with the reference clearance method than the conventional PETIA method in patients with reduced kidney function. Risk of all-cause mortality and combined events, defined by death and myocardial infarction, increased with higher cystatin C and cystatin C remained an independent predictor of death and combined events after adjustment to nonbiochemical baseline factors. In conclusion, the developed dry-reagent double monoclonal assay allows rapid and reliable quantitative measurement of cystatin C. As measured with the developed assay, cystatin C is a potential predictor of adverse outcomes in cardiac patients.

Power semiconductor nonlinearities in active du/dt output filtering

This doctoral thesis introduces an improved control principle for active du/dt output filtering in variable-speed AC drives, together with performance comparisons with previous filtering methods. The effects of power semiconductor nonlinearities on the output filtering performance are investigated. The nonlinearities include the timing deviation and the voltage pulse waveform distortion in the variable-speed AC drive output bridge. Active du/dt output filtering (ADUDT) is a method to mitigate motor overvoltages in variable-speed AC drives with long motor cables. It is a quite recent addition to the du/dt reduction methods available. This thesis improves on the existing control method for the filter, and concentrates on the lowvoltage (below 1 kV AC) two-level voltage-source inverter implementation of the method. The ADUDT uses narrow voltage pulses having a duration in the order of a microsecond from an IGBT (insulated gate bipolar transistor) inverter to control the output voltage of a tuned LC filter circuit. The filter output voltage has thus increased slope transition times at the rising and falling edges, with an opportunity of no overshoot. The effect of the longer slope transition times is a reduction in the du/dt of the voltage fed to the motor cable. Lower du/dt values result in a reduction in the overvoltage effects on the motor terminals. Compared with traditional output filtering methods to accomplish this task, the active du/dt filtering provides lower inductance values and a smaller physical size of the filter itself. The filter circuit weight can also be reduced. However, the power semiconductor nonlinearities skew the filter control pulse pattern, resulting in control deviation. This deviation introduces unwanted overshoot and resonance in the filter. The controlmethod proposed in this thesis is able to directly compensate for the dead time-induced zero-current clamping (ZCC) effect in the pulse pattern. It gives more flexibility to the pattern structure, which could help in the timing deviation compensation design. Previous studies have shown that when a motor load current flows in the filter circuit and the inverter, the phase leg blanking times distort the voltage pulse sequence fed to the filter input. These blanking times are caused by excessively large dead time values between the IGBT control pulses. Moreover, the various switching timing distortions, present in realworld electronics when operating with a microsecond timescale, bring additional skew to the control. Left uncompensated, this results in distortion of the filter input voltage and a filter self-induced overvoltage in the form of an overshoot. This overshoot adds to the voltage appearing at the motor terminals, thus increasing the transient voltage amplitude at the motor. This doctoral thesis investigates the magnitude of such timing deviation effects. If the motor load current is left uncompensated in the control, the filter output voltage can overshoot up to double the input voltage amplitude. IGBT nonlinearities were observed to cause a smaller overshoot, in the order of 30%. This thesis introduces an improved ADUDT control method that is able to compensate for phase leg blanking times, giving flexibility to the pulse pattern structure and dead times. The control method is still sensitive to timing deviations, and their effect is investigated. A simple approach of using a fixed delay compensation value was tried in the test setup measurements. The ADUDT method with the new control algorithm was found to work in an actual motor drive application. Judging by the simulation results, with the delay compensation, the method should ultimately enable an output voltage performance and a du/dt reduction that are free from residual overshoot effects. The proposed control algorithm is not strictly required for successful ADUDT operation: It is possible to precalculate the pulse patterns by iteration and then for instance store them into a look-up table inside the control electronics. Rather, the newly developed control method is a mathematical tool for solving the ADUDT control pulses. It does not contain the timing deviation compensation (from the logic-level command to the phase leg output voltage), and as such is not able to remove the timing deviation effects that cause error and overshoot in the filter. When the timing deviation compensation has to be tuned-in in the control pattern, the precalculated iteration method could prove simpler and equally good (or even better) compared with the mathematical solution with a separate timing compensation module. One of the key findings in this thesis is the conclusion that the correctness of the pulse pattern structure, in the sense of ZCC and predicted pulse timings, cannot be separated from the timing deviations. The usefulness of the correctly calculated pattern is reduced by the voltage edge timing errors. The doctoral thesis provides an introductory background chapter on variable-speed AC drives and the problem of motor overvoltages and takes a look at traditional solutions for overvoltage mitigation. Previous results related to the active du/dt filtering are discussed. The basic operation principle and design of the filter have been studied previously. The effect of load current in the filter and the basic idea of compensation have been presented in the past. However, there was no direct way of including the dead time in the control (except for solving the pulse pattern manually by iteration), and the magnitude of nonlinearity effects had not been investigated. The enhanced control principle with the dead time handling capability and a case study of the test setup timing deviations are the main contributions of this doctoral thesis. The simulation and experimental setup results show that the proposed control method can be used in an actual drive. Loss measurements and a comparison of active du/dt output filtering with traditional output filtering methods are also presented in the work. Two different ADUDT filter designs are included, with ferrite core and air core inductors. Other filters included in the tests were a passive du/dtfilter and a passive sine filter. The loss measurements incorporated a silicon carbide diode-equipped IGBT module, and the results show lower losses with these new device technologies. The new control principle was measured in a 43 A load current motor drive system and was able to bring the filter output peak voltage from 980 V (the previous control principle) down to 680 V in a 540 V average DC link voltage variable-speed drive. A 200 m motor cable was used, and the filter losses for the active du/dt methods were 111W–126 W versus 184 W for the passive du/dt. In terms of inverter and filter losses, the active du/dt filtering method had a 1.82-fold increase in losses compared with an all-passive traditional du/dt output filter. The filter mass with the active du/dt method was 17% (2.4 kg, air-core inductors) compared with 14 kg of the passive du/dt method filter. Silicon carbide freewheeling diodes were found to reduce the inverter losses in the active du/dt filtering by 18% compared with the same IGBT module with silicon diodes. For a 200 m cable length, the average peak voltage at the motor terminals was 1050 V with no filter, 960 V for the all-passive du/dt filter, and 700 V for the active du/dt filtering applying the new control principle.

Primary and Revision Hip Replacement. A University Hospital Database and Registry Study

Large-headed total hip arthroplasty (THA) and hip resurfacing arthroplasty (HRA) with metal-on-metal (MoM) bearings became popular during the last decade. Recently, it has become evident that the large-head MoM hip implants are associated with increased revision rates despite their theoretical advantages. The purpose of this study was to evaluate the early results of primary MoM hip replacements and of acetabular revisions. I analyzed retrospectively the results of four MoM implant designs and the survival rate of acetabular revisions with impaction bone grafting, as documented in the Turku University Hospital database. Further, I evaluated the correlation between femoral head size and dislocation rate, and used the Finnish Arthroplasty Register data to compare the survival of three large-head MoM THAs to analogous HRAs. The early results for the Magnum M2A–ReCap THA were good. A larger head size decreased the risk of dislocation. Articular surface replacement (ASR) THA yielded inferior results compared to analogous HRA. For two other designs the results were similar. The R3–Synergy THA yielded inferior results compared to the reference implants. The survival of acetabular reconstructions with impaction bone grafting was inferior compared to previous reports. In conclusion, the early results of the Biomet ReCap–Magnum design were promising, and large head sizes decreased the dislocation rate. The survival of different MoM hip implant designs varied. The survival of new designs and techniques may be inferior to those reported by the clinics where implants are developed. An important caveat is that early promising results of new devices may rapidly worsen. New implants need to be introduced in a controlled fashion to the market; here, arthroplasty registers are a valuable tool that needs to be used.