155 resultados para power position
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Markku Laitinen's keynote presentation in the QQML conference in Limerick, Ireland the 23rd of April, 2012.
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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.
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This thesis consists of four articles and an introductory section. The main research questions in all the articles refer to the changes in the representativeness of the Finnish Paper Workers' Union. Representativeness stands for the entire entity of external, internal, legal and reputational factors that enable the labor union to represent its members and achieve its goals. This concept is based on an extensive reading of quantitative and qualitative industrial relations literature, which includes works based on Marxist labor-capital relations (such as Hyman's industrial relations studies), and more recent union density studies as well as gender- and ethnic diversity-based 'union revitalization' studies. Müller-Jentsch's German studies of industrial relations have been of particular importance as well as Streeck's industrial unionism and technology studies. The concept of representativeness is an attempt to combine the insights of these diverse strands of literature and bring the scientific discussion of labor unions back to the core of a union's function: representing its members. As such, it can be seen as a theoretical innovation. The concept helps to acknowledge both the heterogeneity of the membership and the totality of a labor union organization. The concept of representativeness aims to move beyond notions of 'power'. External representativeness can be expressed through the position of the labor union in the industrial relations system and the economy. Internal representativeness focuses on the aspects of labor unions that relate to the function of the union as an association with members, such as internal democracy. Legal representativeness lies in the formal legal position of the union – its rights and instruments. This includes collective bargaining legislation, co-decision rules and industrial conflict legislation. Reputational representativeness is related to how the union is seen by other actors and the general public, and can be approximated using data on strike activity. All these aspects of representativeness are path-dependent, and show the results of previous struggles over issues. The concept of representativeness goes beyond notions of labor union power and symbolizes an attempt to bring back the focus of industrial relations studies to the union's basic function of representing its members. The first article shows in detail the industrial conflict of the Finnish paper industry in 2005. The intended focus was the issue of gender in the negotiations over a new collective agreement, but the focal point of the industrial conflict was the issue of outsourcing and how this should be organized. Also, the issue of continuous shifts as an issue of working time was very important. The drawn-out conflict can be seen as a struggle over principles, and under pressure the labor union had to concede ground on the aforementioned issues. The article concludes that in this specific conflict, the union represented its' female members to a lesser extent, because the other issues took such priority. Furthermore, because of the substantive concessions. the union lost some of its internal representativeness, and the stubbornness of the union may have even harmed the reputation of the union. This article also includes an early version of the representativeness framework, through which this conflict is analyzed. The second article discusses wage developments, union density and collective bargaining within the context of representativeness. It is shown that the union has been able to secure substantial benefits for its members, regardless of declining employment. Collective agreements have often been based on centralized incomes policies, but the paper sector has not always joined these. Attention is furthermore paid to the changing competition of the General Assembly, with a surprisingly strong position of the Left Alliance still. In an attempt to replicate analysis of union density measures, an analysis of sectoral union density shows that similar factors as in aggregate data influence this measure, though – due to methodological issues – the results may not be robust. On this issue, it can be said that the method of analysis for aggregate union density is not suitable for sectoral union density analysis. The increasingly conflict-ridden industrial relations predicted have not actually materialized. The article concludes by asking whether the aim of ever-increasing wages is a sustainable one in the light of the pressures of globalization, though wage costs are a relatively small part of total costs. The third article discusses the history and use of outsourcing in the Finnish paper industry. It is shown using Hyman's framework of constituencies that over time, the perspective of the union changed from 'members of the Paper Workers' Union' to a more specific view of who is a core member of the union. Within the context of the industrial unionism that the union claims to practice, this is an important change. The article shows that the union more and more caters for a core group, while auxiliary personnel is less important to the union's identity and constituencies, which means that the union's internal representativeness has decreased. Maintenance workers are an exception; the union and employers have developed a rotating system that increases the efficient allocation of these employees. The core reason of the exceptional status of maintenance personnel is their high level of non-transferable skills. In the end it is debatable whether the compromise on outsourcing solves the challenges facing the industry. The fourth article shows diverging discourses within the union with regard to union-employer partnership for competitiveness improvements and instruments of local union representatives. In the collective agreement of 2008, the provision regulating wage effects of significant changes in the organization or content of work was thoroughly changed, though this mainly reflected decisions by the Labor Court on the pre-2008 version of the provision. This change laid bare the deep rift between the Social Democratic and Left Alliance (ex-Communist) factions of the union. The article argues that through the changed legal meaning of the provision, the union was able to transform concession bargaining into a basis for partnership. The internal discontent about this issue is nonetheless substantial and a threat to the unity of the union, both locally and at the union level. On the basis of the results of the articles, other factors influencing representativeness, such as technology and EU law and an overview of the main changes in the Finnish paper industry, it is concluded that, especially in recent years, the Finnish Paper Workers' Union has lost some of its representativeness. In particular, the loss of the efficiency of strikes is noted, the compromise on outsourcing which may have alienated a substantial part of the union's membership, and the change in the collective agreement of 2008 have caused this decline. In the latter case, the internal disunion on that issue shows the constraints of the union's internal democracy. Furthermore, the failure of the union to join the TEAM industrial union (by democratic means), the internal conflicts and a narrow focus on its own sector may also hurt the union in the future, as the paper industry in Finland is going through a structural change. None of these changes in representativeness would have been so drastic without the considerable pressure of globalization - in particular changing markets, changing technology and a loss of domestic investments to foreign investments, which in the end have benefited the corporations more than the Finnish employees of these corporations. Taken together, the union risks becoming socially irrelevant in time, though it will remain formally very strong on the basis of its institutional setting and financial situation.
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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.
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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.
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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.
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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.
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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.
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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.
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14 x 22 cm
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In ship and offshore terminal construction, welded cross sections are thick and the number of welds very high. Consequently, there are two aspects of great importance; cost and heat input. Reduction in the welding operation time decreases the costs of the work force and avoids excessive heat, preventing distortion and other weld defects. The need to increase productivity while using a single wire in the GMAW process has led to the use of a high current and voltage to improve the melting rate. Unfortunately, this also increases the heat input. Innovative GMAW processes, mostly implemented for sheet plate sections, have shown significant reduction in heat input (Q), low distortion and increase in welding speed. The aim of this study is to investigate adaptive pulsed GMAW processes and assess relevant applications in the high power range, considering possible benefits when welding thicker sections and high yield strength steel. The study experimentally tests the usability of adaptive welding processes and evaluates their effects on weld properties, penetration and shapes of the weld bead.The study first briefly reviews adaptive GMAW to evaluate different approaches and their applications and to identify benefits in adaptive pulsed. Experiments are then performed using Synergic Pulsed GMAW, WiseFusionTM and Synergic GMAW processes to weld a T-joint in a horizontal position (PB). The air gap between the parts ranges from 0 to 2.5 mm. The base materials are structural steel grade S355MC and filler material G3Si1. The experiment investigates heat input, mechanical properties and microstructure of the welded joint. Analysis of the literature reveals that different approaches have been suggested using advanced digital power sources with accurate waveform, current, voltage, and feedback control. In addition, studies have clearly indicated the efficiency of lower energy welding processes. Interest in the high power range is growing and a number of different approaches have been suggested. The welding experiments in this study reveal a significant reduction of heat input and a weld microstructure with the presence of acicular ferrite (AF) beneficial for resistance to crack propagation. The WiseFusion bead had higher dilution, due to the weld bead shape, and low defects. Adaptive pulse GMAW processes can be a favoured choice when welding structures with many welded joints. The total heat reduction mitigates residual stresses and the bead shape allows a higher amperage limit. The stability of the arc during the process is virtually spatter free and allows an increase in welding speed.
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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.
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14 x 22 cm
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kuv., 14 x 22 cm
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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.