LVI- ja sähköurakoinnin raportoinnin kehittäminen IT-palveluyrityksessä

Työn tavoitteena oli kehittää LVI- ja sähköurakointitoimialan asiakkaille tarjottavaa raportointia IT-palveluyrityksessä. Raportoinnin tulisi soveltua paremmin yrityksen ohjaamiseen ja sen avulla yrityksen tulisi tietää kannattavuutensa, rahoitustilanteensa ja liiketoimintansa kehityssuunnat. Tarkoituksena oli suunnitella raportointimalli, joka soveltuu toimialan pienten ja keskisuurten yritysten käyttöön. Tutkimus toteutettiin konstruktiivisena eli tutkimuksen tavoitteena oli luoda uusi ratkaisumalli käytännön ongelmaan. Konstruktion rakentamiseksi työssä selvitettiin LVI- ja sähköurakoinnin erityispiirteitä, yrityksen ohjaukseen vaikuttavia tekijöitä ja menetelmiä sekä raportoinnin periaatteellista ja teknistä toteuttamista. Näiden osa-alueiden avulla luotiin raportointimallille vaatimukset, jotka sen tulisi täyttää. Tämän jälkeen kuvattiin raportoinnin nykyinen tekninen toteutustapa ja sen sisältämät osa-alueet. Selvitettyjen vaatimusten ja nykyisen raportoinnin ongelmien perusteella luotiin alustava raportointimalli, jonka käytännön merkitys selvitettiin haastattelemalla 11 LVI- ja sähköurakointiyrityksen vastuunalaista johtajaa. Haastatteluista saatiin selville, että kahdeksan johtajaa olisi ollut valmis käyttämään konstruktiota. Alustavan raportointimallin ja haastatteluista saadun palautteen perusteella luotiin ehdotus raportointimallista toimialalla. Lisäksi IT-palveluyrityksen nykyiselle raportointimallille luotiin kolmivaiheinen kehityssuunnitelma, jolla raportointia voidaan kehittää luodun raportointimallin mukaiseksi.

Electrical characteristics of eddy current position sensor

In the thesis the principle of work of eddy current position sensors and the main cautions that must be taken into account while sensor design process are explained. A way of automated eddy current position sensor electrical characteristics measurement is suggested. A prototype of the eddy current position sensor and its electrical characteristics are investigated. The results obtained by means of the automated measuring system are explained.

DFM(A)- aspects for a fixed electrical attenuator design

The goal of this paper is to describe a complete and extensive prototype design of a fixed electrical attenuator. The paper starts by describing the function and by giving some basic information about the attenuators. After a comprehensive description of the component, the facts of reverse engineering are discussed. The method itself is applied to ease manufacturing and design stages of this component. Information about materials and applied manufacturing technologies are also included in this report. By applying some specified DFMA-aspects the final design turned out to be a potential prototype device to be manufactured and for further analyse.

Statistical Inversion Theory in X-ray Tomography

In this thesis the X-ray tomography is discussed from the Bayesian statistical viewpoint. The unknown parameters are assumed random variables and as opposite to traditional methods the solution is obtained as a large sample of the distribution of all possible solutions. As an introduction to tomography an inversion formula for Radon transform is presented on a plane. The vastly used filtered backprojection algorithm is derived. The traditional regularization methods are presented sufficiently to ground the Bayesian approach. The measurements are foton counts at the detector pixels. Thus the assumption of a Poisson distributed measurement error is justified. Often the error is assumed Gaussian, altough the electronic noise caused by the measurement device can change the error structure. The assumption of Gaussian measurement error is discussed. In the thesis the use of different prior distributions in X-ray tomography is discussed. Especially in severely ill-posed problems the use of a suitable prior is the main part of the whole solution process. In the empirical part the presented prior distributions are tested using simulated measurements. The effect of different prior distributions produce are shown in the empirical part of the thesis. The use of prior is shown obligatory in case of severely ill-posed problem.

Radio Frequency Measurement Method for Detecting Bearing Currents in Induction Motors

Induction motors are widely used in industry, and they are generally considered very reliable. They often have a critical role in industrial processes, and their failure can lead to significant losses as a result of shutdown times. Typical failures of induction motors can be classified into stator, rotor, and bearing failures. One of the reasons for a bearing damage and eventually a bearing failure is bearing currents. Bearing currents in induction motors can be divided into two main categories; classical bearing currents and inverter-induced bearing currents. A bearing damage caused by bearing currents results, for instance, from electrical discharges that take place through the lubricant film between the raceways of the inner and the outer ring and the rolling elements of a bearing. This phenomenon can be considered similar to the one of electrical discharge machining, where material is removed by a series of rapidly recurring electrical arcing discharges between an electrode and a workpiece. This thesis concentrates on bearing currents with a special reference to bearing current detection in induction motors. A bearing current detection method based on radio frequency impulse reception and detection is studied. The thesis describes how a motor can work as a “spark gap” transmitter and discusses a discharge in a bearing as a source of radio frequency impulse. It is shown that a discharge, occurring due to bearing currents, can be detected at a distance of several meters from the motor. The issues of interference, detection, and location techniques are discussed. The applicability of the method is shown with a series of measurements with a specially constructed test motor and an unmodified frequency-converter-driven motor. The radio frequency method studied provides a nonintrusive method to detect harmful bearing currents in the drive system. If bearing current mitigation techniques are applied, their effectiveness can be immediately verified with the proposed method. The method also gives a tool to estimate the harmfulness of the bearing currents by making it possible to detect and locate individual discharges inside the bearings of electric motors.

Overvoltage Mitigation Techniques in Wind Power Generators

Advancements in power electronic semiconductor switching devices have lead to significantly faster switching times. In motor and generator applications, the fast switching times of pulse width modulated (PWM) inverters lead to overvoltages caused by voltage reflections with shorter and shorter cables. These excessive overvoltages may lead to a failure of the electrical machine in a matter of months. In this thesis, the causes behind the overvoltage phenomenon as well as its different mitigation techniques are studied. The most suitable techniques for mitigating the overvoltage phenomenon in wind power generator applications are chosen based on both simulations and actual measurements performed on a prototype. An RC filter at the terminals of the electrical machine and an inverter output filter designed to reduce the rise and fall times of voltage pulses are presented as a solution to the overvoltage problem. The performance and losses of both filter types are analysed.

Impedance field and noise of submicrometer n+ nn+ diodes: analytical approach

A theoretical model for the noise properties of n+nn+ diodes in the drift-diffusion framework is presented. In contrast with previous approaches, our model incorporates both the drift and diffusive parts of the current under inhomogeneous and hot-carrier conditions. Closed analytical expressions describing the transport and noise characteristics of submicrometer n+nn+ diodes, in which the diode base (n part) and the contacts (n+ parts) are coupled in a self-consistent way, are obtained

Aplicació de tècniques geofísiques electromagnètiques a la localització de zones afectades per abocaments incontrolats de residus

Increase of the metropolitan area of cities provoking a progressive settlement of zones that previously had a different territorial use. These zones are usually located within city houndaries and for many years have been affected hy the waste of many kinds of residues. Qualitative analysis of the electrical behaviour of soil, based on maps and cross sections of apparent conductivity, allows us to locate anomalies generated by the wastes. Moreover, the electrornagnetic techniques (EM-31 and EM-34 Geonics devices) are cheaper than other survey methods. Two examples in the campus of the University of Girona, in the southern area of Girona city, illustrate the environmental problem and the applicability of the geophysical method

Ionospheric tomography using GNSS reflections

In this paper, we report a preliminary analysis of the impact of Global Navigation Satellite System Reflections (GNSS-R) data on ionospheric monitoring over the oceans. The focus will be on a single polar Low Earth Orbiter (LEO) mission exploiting GNSS-R as well as Navigation (GNSS-N) and Occultation (GNSS-O) total electron content (TEC) measurements. In order to assess impact of the data, we have simulated GNSS-R/O/N TEC data as would be measured from the LEO and from International Geodesic Service (IGS) ground stations, with an electron density (ED) field generated using a climatic ionospheric model. We have also developed a new tomographic approach inspired by the physics of the hydrogen atom and used it to effectively retrieve the ED field from the simulated TEC data near the orbital plane. The tomographic inversion results demonstrate the significant impact of GNSS-R: three-dimensional ionospheric ED fields are retrieved over the oceans quite accurately, even as, in the spirit of this initial study, the simulation and inversion approaches avoided intensive computation and sophisticated algorithmic elements (such as spatio-temporal smoothing). We conclude that GNSS-R data over the oceans can contribute significantly to a Global/GNSS Ionospheric Observation System (GIOS). Index Terms Global Navigation Satellite System (GNSS), Global Navigation Satellite System Reflections (GNSS-R), ionosphere, Low Earth Orbiter (LEO), tomography.

Free Flap Monitoring. Using Tissue Oxygen Measurement and Positron Emission Tomography

Aims:This study was carried out to evaluate the feasibility of two different methods to determine free flap perfusion in cancer patients undergoing major reconstructive surgery. The hypotheses was that low perfusion in the flap is associated with flap complications. Patients and methods: Between August 2002 and June 2008 at the Department of Otorhinolaryngology – Head and Neck Surgery, Department of Surgery, and at the PET Centre, Turku, 30 consecutive patients with 32 free flaps were included in this study. The perfusion of the free microvascular flaps was assessed with positron emission tomography (PET) and radioactive water ([¹⁵O] H₂O) in 40 radiowater injections in 33 PET studies. Furthermore, 24 free flaps were monitored with a continuous tissue oxygen measurement using flexible polarographic catheters for an average of three postoperative days. Results: Of the 17 patients operated on for head and neck (HN) cancer and reconstructed with 18 free flaps, three re-operations were carried out due to poor tissue oxygenation as indicated by p_tiO₂ monitoring results and three other patients were reoperated on for postoperative hematomas in the operated area. Blood perfusion assessed with PET (BF_PET) was above 2.0 mL / min / 100 g in all flaps and a low flap-to-muscle BFPET ratio appeared to correlate with poor survival of the flap. Survival in this group of HN cancer patients was 9.0 months (median, range 2.4-34.2) after a median follow-up of 11.9 months (range 1.0-61.0 months). Seven HN patients of this group are alive without any sign of recurrence and one patient has died of other causes. All of the 13 breast reconstruction patients included in the study are alive and free of disease at a median follow-up time of 27.4 months (range 13.9-35.7 months). Re-explorations were carried out in three patients due data provided by p_tiO₂ monitoring and one re-exploration was avoided on the basis of adequate blood perfusion assessed with PET. Two patients had donorsite morbidity and 3 patients had partial flap necrosis or fat necrosis. There were no total flap losses. Conclusions: P_tiO₂ monitoring is a feasible method of free flap monitoring when flap temperature is monitored and maintained close to the core temperature. When other monitoring methods give controversial results or are unavailable, [₁₅O] H₂O PET technique is feasible in the evaluation of the perfusion of the newly reconstructed free flaps.

Active du/dt Filtering for Variable-Speed AC Drives

An oscillating overvoltage has become a common phenomenon at the motor terminal in inverter-fed variable-speed drives. The problem has emerged since modern insulated gate bipolar transistors have become the standard choice as the power switch component in lowvoltage frequency converter drives. Theovervoltage phenomenon is a consequence of the pulse shape of inverter output voltage and impedance mismatches between the inverter, motor cable, and motor. The overvoltages are harmful to the electric motor, and may cause, for instance, insulation failure in the motor. Several methods have been developed to mitigate the problem. However, most of them are based on filtering with lossy passive components, the drawbacks of which are typically their cost and size. In this doctoral dissertation, application of a new active du/dt filtering method based on a low-loss LC circuit and active control to eliminate the motor overvoltages is discussed. The main benefits of the method are the controllability of the output voltage du/dt within certain limits, considerably smaller inductances in the filter circuit resulting in a smaller physical component size, and excellent filtering performance when compared with typical traditional du/dt filtering solutions. Moreover, no additional components are required, since the active control of the filter circuit takes place in the process of the upper-level PWM modulation using the same power switches as the inverter output stage. Further, the active du/dt method will benefit from the development of semiconductor power switch modules, as new technologies and materials emerge, because the method requires additional switching in the output stage of the inverter and generation of narrow voltage pulses. Since additional switching is required in the output stage, additional losses are generated in the inverter as a result of the application of the method. Considerations on the application of the active du/dt filtering method in electric drives are presented together with experimental data in order to verify the potential of the method.

Combined dielectrophoretic and impedance system for on-chip controlled bacteria concentration: Application to Escherichia coli

The present paper reports a bacteria autonomous controlled concentrator prototype with a user-friendly interface for bench-top applications. It is based on a micro-fluidic lab-on-a-chip and its associated custom instrumentation, which consists in a dielectrophoretic actuator, to pre-concentrate the sample, and an impedance analyser, to measure concentrated bacteria levels. The system is composed by a single micro-fluidic chamber with interdigitated electrodes and a instrumentation with custom electronics. The prototype is supported by a real-time platform connected to a remote computer, which automatically controls the system and displays impedance data used to monitor the status of bacteria accumulation on-chip. The system automates the whole concentrating operation. Performance has been studied for controlled volumes of Escherichia coli (E. coli) samples injected into the micro-fluidic chip at constant flow rate of 10 μL/min. A media conductivity correcting protocol has been developed, as the preliminary results showed distortion of the impedance analyser measurement produced by bacterial media conductivity variations through time. With the correcting protocol, the measured impedance values were related to the quantity of bacteria concentrated with a correlation of 0.988 and a coefficient of variation of 3.1%. Feasibility of E. coli on-chip automated concentration, using the miniaturized system, has been demonstrated. Furthermore, the impedance monitoring protocol had been adjusted and optimized, to handle changes in the electrical properties of the bacteria media over time.

Retrieval of kinetic rates in reactions with semi batch liquid phase using ill-posed inverse problem theory

A neural network procedure to solve inverse chemical kinetic problems is discussed in this work. Rate constants are calculated from the product concentration of an irreversible consecutive reaction: the hydrogenation of Citral molecule, a process with industrial interest. Simulated and experimental data are considered. Errors in the simulated data, up to 7% in the concentrations, were assumed to investigate the robustness of the inverse procedure. Also, the proposed method is compared with two common methods in nonlinear analysis; the Simplex and Levenberg-Marquardt approaches. In all situations investigated, the neural network approach was numerically stable and robust with respect to deviations in the initial conditions or experimental noises.

Simple method for mass production of polypyrrole/carbon nanotubes hybrid artificial muscle

Large scale preparation of hybrid electrical actuators represents an important step for the production of low cost devices. Interfacial polymerization of polypyrrole in the presence of multi-walled carbon nanotubes represents a simple technique in which strong interaction between components is established, providing composite materials with potential applications as actuators due to the synergistic interaction between the individual components, i.e., fast response of carbon nanotubes, high strain of polypyrrole, and diversity in the available geometry of resulting samples.

Early Detection of Alzheimer's Disease Beta-amyloid Pathology -Applicability of Positron Emission Tomography with the Amyloid Radioligand 11C-PIB

Early Detection of Alzheimer's Disease Beta-amyloid Pathology -Applicability of Positron Emission Tomography with the Amyloid Radioligand ¹¹C-PIB Accumulation of beta amyloid (Abeta) in the brain is characteristic for Alzheimer’s disease (AD). Carbon-11 labeled 2-(4’-methylaminophenyl)-6-hydroxybenzothiazole (¹¹C-PIB) is a novel positron emission tomography (PET) amyloid imaging agent that appears to be applicable for in vivo Abeta plaque detection and quantitation. The biodistribution and radiation dosimetry of ¹¹C-PIB were investigated in 16 healthy subjects. The reproducibility of a simplified ¹¹C-PIB quantitation method was evaluated with a test-retest study on 6 AD patients and 4 healthy control subjects. Brain ¹¹C-PIB uptake and its possible association with brain atrophy rates were studied over a two-year follow-up in 14 AD patients and 13 healthy controls. Nine monozygotic and 8 dizygotic twin pairs discordant for cognitive impairment and 9 unrelated controls were examined to determine whether brain Abeta accumulation could be detected with ¹¹C-PIB PET in cognitively intact persons who are at increased genetic risk for AD. The highest absorbed radiation dose was received by the gallbladder wall (41.5 mjuGy/MBq). About 20 % of the injected radioactivity was excreted into urine, and the effective whole-body radiation dose was 4.7 mjuSv/MBq. Such a dose allows repeated scans of individual subjects. The reproducibility of the simplified ¹¹C-PIB quantitation was good or excellent both at the regional level (VAR 0.9-5.5 %) and at the voxel level (VAR 4.2-6.4 %). ¹¹C-PIB uptake did not increase during 24 months’ follow-up of subjects with mild or moderate AD, even though brain atrophy and cognitive decline progressed. Baseline neocortical ¹¹C-PIB uptake predicted subsequent volumetric brain changes in healthy control subjects (r = 0.725, p = 0.005). Cognitively intact monozygotic co-twins – but not dizygotic co-twins – of memory-impaired subjects exhibited increased ¹¹C-PIB uptake (117-121 % of control mean) in their temporal and parietal cortices and the posterior cingulate (p<0.05), when compared with unrelated controls. This increased uptake may be representative of an early AD process, and genetic factors seem to play an important role in the development of AD-like Abeta plaque pathology. ¹¹C-PIB PET may be a useful method for patient selection and follow-up for early-phase intervention trials of novel therapeutic agents. AD might be detectable in high-risk individuals in its presymptomatic stage with ¹¹C-PIB PET, which would have important consequences both for future diagnostics and for research on disease-modifying treatments.