The Power of Data - Advocating for Library by Showing Evidence of Impact

Markku Laitinen's keynote presentation in the QQML conference in Limerick, Ireland the 23rd of April, 2012.

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.

The Design and Implementation of a Power Management Feature to a Configuration Management System

Green IT is a term that covers various tasks and concepts that are related to reducing the environmental impact of IT. At enterprise level, Green IT has significant potential to generate sustainable cost savings: the total amount of devices is growing and electricity prices are rising. The lifecycle of a computer can be made more environmentally sustainable using Green IT, e.g. by using energy efficient components and by implementing device power management. The challenge using power management at enterprise level is how to measure and follow-up the impact of power management policies? During the thesis a power management feature was developed to a configuration management system. The feature can be used to automatically power down and power on PCs using a pre-defined schedule and to estimate the total power usage of devices. Measurements indicate that using the feature the device power consumption can be monitored quite precisely and the power consumption can be reduced, which generates electricity cost savings and reduces the environmental impact of IT.

Intrapartum hypoxia and power spectral analysis of fetal heart rate variability

Reliable detection of intrapartum fetal acidosis is crucial for preventing morbidity. Hypoxia-related changes of fetal heart rate variability (FHRV) are controlled by the autonomic nervous system. Subtle changes in FHRV that cannot be identified by inspection can be detected and quantified by power spectral analysis. Sympathetic activity relates to low-frequency FHRV and parasympathetic activity to both low- and high-frequency FHRV. The aim was to study whether intra partum fetal acidosis can be detected by analyzing spectral powers of FHRV, and whether spectral powers associate with hypoxia-induced changes in the fetal electrocardiogram and with the pH of fetal blood samples taken intrapartum. The FHRV of 817 R-R interval recordings, collected as a part of European multicenter studies, were analyzed. Acidosis was defined as cord pH ≤ 7.05 or scalp pH ≤ 7.20, and metabolic acidosis as cord pH ≤ 7.05 and base deficit ≥ 12 mmol/l. Intrapartum hypoxia increased the spectral powers of FHRV. As fetal acidosis deepened, FHRV decreased: fetuses with significant birth acidosis had, after an initial increase, a drop in spectral powers near delivery, suggesting a breakdown of fetal compensation. Furthermore, a change in excess of 30% of the low-to-high frequency ratio of FHRV was associated with fetal metabolic acidosis. The results suggest that a decrease in the spectral powers of FHRV signals concern for fetal wellbeing. A single measure alone cannot be used to reveal fetal hypoxia since the spectral powers vary widely intra-individually. With technical developments, continuous assessment of intra-individual changes in spectral powers of FHRV might aid in the detection of fetal compromise due to hypoxia.

Chelyabinsk CHP-3 “locked power” problem solving

All over the world power systems become bigger and bigger every day. New equipment is installed, new feeders are constructed, new power units are installed. Some old elements of the network, however, are not changed in time. As a result, “bottlenecks” for capacity transmission can occur. By locked power problem the situation when a power plant has installed capacity exceeding the power it can actually deliver is usually meant. Regime, scheme or even technical restrictions-related issues usually cause this kind of problem. It is really important, since from the regime point of view it is typical decision to have a mobile capacity reserve, in case of malfunctions. And, what can be even more significant, power plant owner (JSC Fortum in our case) losses his money because of selling less electrical energy. The goal of master`s thesis is to analyze the current state of Chelyabinsk power system and the CHP-3 (Combined Heat and Power plant) in particular in relation with it`s ability to deliver the whole capacity of the CHP in it`s existing state and also taking into consideration the prospect of power unit 3 installation by the fourth quarter of 2010. The thesis contains some general information about the UPS of Russia, CPS of Ural, power system of Chelyabinsk and the Chelyabinsk region itself. Then the CHP-3 is described from technical point of view with it`s equipment observation. Regimes for the nowadays power system and for the system after the power unit 3 installation are reviewed. The problems occurring are described and, finally, a solution is offered.

Exploration and Design of Power-Efficient Networked Many-Core Systems

Multiprocessing is a promising solution to meet the requirements of near future applications. To get full benefit from parallel processing, a manycore system needs efficient, on-chip communication architecture. Networkon- Chip (NoC) is a general purpose communication concept that offers highthroughput, reduced power consumption, and keeps complexity in check by a regular composition of basic building blocks. This thesis presents power efficient communication approaches for networked many-core systems. We address a range of issues being important for designing power-efficient manycore systems at two different levels: the network-level and the router-level. From the network-level point of view, exploiting state-of-the-art concepts such as Globally Asynchronous Locally Synchronous (GALS), Voltage/ Frequency Island (VFI), and 3D Networks-on-Chip approaches may be a solution to the excessive power consumption demanded by today’s and future many-core systems. To this end, a low-cost 3D NoC architecture, based on high-speed GALS-based vertical channels, is proposed to mitigate high peak temperatures, power densities, and area footprints of vertical interconnects in 3D ICs. To further exploit the beneficial feature of a negligible inter-layer distance of 3D ICs, we propose a novel hybridization scheme for inter-layer communication. In addition, an efficient adaptive routing algorithm is presented which enables congestion-aware and reliable communication for the hybridized NoC architecture. An integrated monitoring and management platform on top of this architecture is also developed in order to implement more scalable power optimization techniques. From the router-level perspective, four design styles for implementing power-efficient reconfigurable interfaces in VFI-based NoC systems are proposed. To enhance the utilization of virtual channel buffers and to manage their power consumption, a partial virtual channel sharing method for NoC routers is devised and implemented. Extensive experiments with synthetic and real benchmarks show significant power savings and mitigated hotspots with similar performance compared to latest NoC architectures. The thesis concludes that careful codesigned elements from different network levels enable considerable power savings for many-core systems.

Power cycling lifetime estimation of IGBT power modules based on chip temperature modeling

In this doctoral thesis, methods to estimate the expected power cycling life of power semiconductor modules based on chip temperature modeling are developed. Frequency converters operate under dynamic loads in most electric drives. The varying loads cause thermal expansion and contraction, which stresses the internal boundaries between the material layers in the power module. Eventually, the stress wears out the semiconductor modules. The wear-out cannot be detected by traditional temperature or current measurements inside the frequency converter. Therefore, it is important to develop a method to predict the end of the converter lifetime. The thesis concentrates on power-cycling-related failures of insulated gate bipolar transistors. Two types of power modules are discussed: a direct bonded copper (DBC) sandwich structure with and without a baseplate. Most common failure mechanisms are reviewed, and methods to improve the power cycling lifetime of the power modules are presented. Power cycling curves are determined for a module with a lead-free solder by accelerated power cycling tests. A lifetime model is selected and the parameters are updated based on the power cycling test results. According to the measurements, the factor of improvement in the power cycling lifetime of modern IGBT power modules is greater than 10 during the last decade. Also, it is noticed that a 10 C increase in the chip temperature cycle amplitude decreases the lifetime by 40%. A thermal model for the chip temperature estimation is developed. The model is based on power loss estimation of the chip from the output current of the frequency converter. The model is verified with a purpose-built test equipment, which allows simultaneous measurement and simulation of the chip temperature with an arbitrary load waveform. The measurement system is shown to be convenient for studying the thermal behavior of the chip. It is found that the thermal model has a 5 C accuracy in the temperature estimation. The temperature cycles that the power semiconductor chip has experienced are counted by the rainflow algorithm. The counted cycles are compared with the experimentally verified power cycling curves to estimate the life consumption based on the mission profile of the drive. The methods are validated by the lifetime estimation of a power module in a direct-driven wind turbine. The estimated lifetime of the IGBT power module in a direct-driven wind turbine is 15 000 years, if the turbine is located in south-eastern Finland.

Analysis and validation of space averaged drag model for numerical simulations of gas-solid flows in fluidized beds

This thesis presents an approach for formulating and validating a space averaged drag model for coarse mesh simulations of gas-solid flows in fluidized beds using the two-fluid model. Proper modeling for fluid dynamics is central in understanding any industrial multiphase flow. The gas-solid flows in fluidized beds are heterogeneous and usually simulated with the Eulerian description of phases. Such a description requires the usage of fine meshes and small time steps for the proper prediction of its hydrodynamics. Such constraint on the mesh and time step size results in a large number of control volumes and long computational times which are unaffordable for simulations of large scale fluidized beds. If proper closure models are not included, coarse mesh simulations for fluidized beds do not give reasonable results. The coarse mesh simulation fails to resolve the mesoscale structures and results in uniform solids concentration profiles. For a circulating fluidized bed riser, such predicted profiles result in a higher drag force between the gas and solid phase and also overestimated solids mass flux at the outlet. Thus, there is a need to formulate the closure correlations which can accurately predict the hydrodynamics using coarse meshes. This thesis uses the space averaging modeling approach in the formulation of closure models for coarse mesh simulations of the gas-solid flow in fluidized beds using Geldart group B particles. In the analysis of formulating the closure correlation for space averaged drag model, the main parameters for the modeling were found to be the averaging size, solid volume fraction, and distance from the wall. The closure model for the gas-solid drag force was formulated and validated for coarse mesh simulations of the riser, which showed the verification of this modeling approach. Coarse mesh simulations using the corrected drag model resulted in lowered values of solids mass flux. Such an approach is a promising tool in the formulation of appropriate closure models which can be used in coarse mesh simulations of large scale fluidized beds.

Modeling and Control of the Power Conversion Unit in a Solid Oxide Fuel Cell Environment

In this doctoral thesis, a power conversion unit for a 10 kWsolid oxide fuel cell is modeled, and a suitable control system is designed. The need for research was identified based on an observation that there was no information available about the characteristics of the solid oxide fuel cell from the perspective of power electronics and the control system, and suitable control methods had not previously been studied in the literature. In addition, because of the digital implementation of the control system, the inherent characteristics of the digital system had to be taken into account in the characteristics of the solid oxide fuel cell (SOFC). The characteristics of the solid oxide fuel cell as well the methods for the modeling and control of the DC/DC converter and the grid converter are studied by a literature survey. Based on the survey, the characteristics of the SOFC as an electrical power source are identified, and a solution to the interfacing of the SOFC in distributed generation is proposed. A mathematical model of the power conversion unit is provided, and the control design for the DC/DC converter and the grid converter is made based on the proposed interfacing solution. The limit cycling phenomenon is identified as a source of low-frequency current ripple, which is found to be insignificant when connected to a grid-tied converter. A method to mitigate a second harmonic originating from the grid interface is proposed, and practical considerations of the operation with the solid oxide fuel cell plant are presented. At the theoretical level, the thesis discusses and summarizes the methods to successfully derive a model for a DC/DC converter, a grid converter, and a power conversion unit. The results of this doctoral thesis can also be used in other applications, and the models and methods can be adopted to similar applications such as photovoltaic systems. When comparing the results with the objectives of the doctoral thesis, we may conclude that the objectives set for the work are met. In this doctoral thesis, theoretical and practical guidelines are presented for the successful control design to connect a SOFC-based distributed generation plant to the utility grid.

Mor-Power auto-akkumulaattoreita

kuv., 14 x 22 cm

Long live! : South African HIV-activism, knowledge and power

Då aktivister i den sydafrikanska organisationen Treatment Action Campaign - TAC- demonstrerar för tillgång till bromsmediciner för den fattiga delen av världen, iklädda T-skjortor med texten "HIV-POSITIV", är de offer samtidigt som de är globala aktörer för en rättvisare värld. Denna typ av aktivism, och särskilt mobiliseringen av kvinnor som lever med hiv och kämpar för tillgång till bromsmediciner, utmanar aktuell, hälso- och hiv-forskning. Vidare kastar hiv-aktivismen ljus på globaliseringens effekter på sjukdom och hälsa. TAC är en hälsorörelse som fokuserar på hiv på såväl ett personligt, nationellt som globalt plan. Genom sitt breda perspektiv förskjuter TAC frågan om hiv från att handla om individuell sjukdom till att beröra ett brett spektrum av politiska frågor. Studien "Long Live! HIV-aktivism, knowledge and power", som grundar sig på ett rikt etnografisk material insamlat i Sydafrika under åren 200-2006, visar hur hiv-aktivisterna utmanar dikotomier mellan socialt och medicinskt, mellan behandling och prevention samt mellan aktör och offer. I TAC:s arbete dekonstrueras också de ofta skarpa konstrasterna mellan expert- och lekmannakunskap, eftersom organisationen belyser hur läkare, patienter och aktivister kan samarbeta för en fungerande hälsovård. Studien granskar hur TAC-aktivister, som lever med hiv, agerar som globala aktörer i sitt arbete för förändring. Studien visar vidare hur TAC-aktivister utmanar hur hiv-prevention och -behandling sätts i motsatsförhållande till varandra och hävdar att man inte kan ha det ena utan det andra. Man kan säga att aktivisternas kritik av hälsopolitik synliggör hur teorier om hälsa och sjukdom, måste ta i beaktande det komplexa förhållandet mellan kön, ras, klass och globala maktstrukturer.

Surface transformation hardening of carbon steel with high power fiber laser

This study investigated the surface hardening of steels via experimental tests using a multi-kilowatt fiber laser as the laser source. The influence of laser power and laser power density on the hardening effect was investigated. The microhardness analysis of various laser hardened steels was done. A thermodynamic model was developed to evaluate the thermal process of the surface treatment of a wide thin steel plate with a Gaussian laser beam. The effect of laser linear oscillation hardening (LLOS) of steel was examined. An as-rolled ferritic-pearlitic steel and a tempered martensitic steel with 0.37 wt% C content were hardened under various laser power levels and laser power densities. The optimum power density that produced the maximum hardness was found to be dependent on the laser power. The effect of laser power density on the produced hardness was revealed. The surface hardness, hardened depth and required laser power density were compared between the samples. Fiber laser was briefly compared with high power diode laser in hardening medium-carbon steel. Microhardness (HV0.01) test was done on seven different laser hardened steels, including rolled steel, quenched and tempered steel, soft annealed alloyed steel and conventionally through-hardened steel consisting of different carbon and alloy contents. The surface hardness and hardened depth were compared among the samples. The effect of grain size on surface hardness of ferritic-pearlitic steel and pearlitic-cementite steel was evaluated. In-grain indentation was done to measure the hardness of pearlitic and cementite structures. The macrohardness of the base material was found to be related to the microhardness of the softer phase structure. The measured microhardness values were compared with the conventional macrohardness (HV5) results. A thermodynamic model was developed to calculate the temperature cycle, Ac1 and Ac3 boundaries, homogenization time and cooling rate. The equations were numerically solved with an error of less than 10-8. The temperature distributions for various thicknesses were compared under different laser traverse speed. The lag of the was verified by experiments done on six different steels. The calculated thermal cycle and hardened depth were compared with measured data. Correction coefficients were applied to the model for AISI 4340 steel. AISI 4340 steel was hardened by laser linear oscillation hardening (LLOS). Equations were derived to calculate the overlapped width of adjacent tracks and the number of overlapped scans in the center of the scanned track. The effect of oscillation frequency on the hardened depth was investigated by microscopic evaluation and hardness measurement. The homogeneity of hardness and hardened depth with different processing parameters were investigated. The hardness profiles were compared with the results obtained with conventional single-track hardening. LLOS was proved to be well suitable for surface hardening in a relatively large rectangular area with considerable depth of hardening. Compared with conventional single-track scanning, LLOS produced notably smaller hardened depths while at 40 and 100 Hz LLOS resulted in higher hardness within a depth of about 0.6 mm.

Limestone Reactions in a Fluidized Bed Heat Exchanger of an Oxy-fuel Circulating Fluidized Bed Boiler

Oxy-fuel combustion in a circulating fluidized bed (CFB) boiler appears to be a promising option for capturing CO2 in power plants. Oxy-fuel combustion is based on burning of fuel in the mixture of oxygen and re-circulated flue gas instead of air. Limestone (CaCO3) is typically used for capturing of SO2 in CFB boilers where limestone calcines to calcium oxide (CaO). Because of high CO2 concentration in oxy-fuel combustion, calcination reaction may be hindered or carbonation, the reverse reaction of calcination, may occur. Carbonation of CaO particles can cause problems especially in the circulation loop of a CFB boiler where temperature level is lower than in the furnace. The aim of the thesis was to examine carbonation of CaO in a fluidized bed heat exchanger of a CFB boiler featuring oxy-fuel combustion. The calculations and analyzing were based on measurement data from an oxy-fuel pilot plant and on 0-dimensional (0D) gas balance of a fluidized bed heat exchanger. Additionally, the objective was to develop a 1-dimensional (1D) model of a fluidized bed heat exchanger by searching a suitable pre-exponential factor for a carbonation rate constant. On the basis of gas measurement data and the 0D gas balance, it was found that the amount of fluidization gas decreased as it flew through the fluidized bed heat exchanger. Most likely the reason for this was carbonation of CaO. It was discovered that temperature has a promoting effect on the reaction rate of carbonation. With the 1D model, a suitable pre-exponential factor for the equation of carbonation rate constant was found. However, during measurements there were several uncertainties, and in the calculations plenty of assumptions were made. Besides, the temperature level in the fluidized bed heat exchanger was relatively low during the measurements. Carbonation should be considered when fluidized bed heat exchangers and the capacity of related fans are designed for a CFB boiler with oxy-fuel combustion.