925 resultados para electric fields


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The number of electric vehicles grows continuously and the implementation of charging electric vehicles is an important issue for the future. Increasing amount of electric vehicles can cause problems to distribution grid by increasing peak load. Currently charging of electric vehicles is uncontrolled, but as the amount of electric vehicles grows, smart charg-ing (controlled charging) will be one possible solution to handle this situation. In this thesis smart charging of electric vehicles is examined from electricity retailers` point of view. The purpose is to find out plausible saving potentials of smart charging, when it´s controlled by price signal. Saving potential is calculated by comparing costs of price signal controlled charging and uncontrolled charging.

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Kirjallisuusarvostelu

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Several degraded areas can be found along the Highway MG-010 that crosses the Espinhaço Mountain Biosphere Reserve in the Brazilian state of Minas Gerais. Restoration by planting the legume Cajanus cajan was implemented in some of these areas. The present study compares plant species richness, diversity, abundance, equitability, similarity, and soil composition between restored and non-restored areas, in an attempt to evaluate the effectiveness of the use of C. cajan in the restoration process in the mountain environment. Each treatment (restored and non-restored) had four sampling areas, each with three 300 m² plots. We counted and identified every individual plant found within these plots. We also collected soil from the superficial layer (0-10 cm) of each sampling area in both treatments. The areas where C. cajan was planted revealed lower species richness, diversity, and plant abundance. The soil of these areas also contained higher levels of Phosphorus and Magnesium. Plant equitability and similarity between plots and other soil components (pH, Nitrogen, Aluminum, Calcium, Potassium, H+Al, sum of bases - SB, cation exchange capacity - CTC, base saturation - V%, aluminum saturation - M%) did not differ between the two treatments. Contrary to the expectations, soil enhancement in the quartzitic soil poor in nutrients in the rupestrian fields can facilitate the invasion by exotic plants, which are not adapted to the lack of nutrients. As it appears, the use of C. cajan in restoration projects represents a mistake and future restoration plans should avoid the use of exotic species, given that they may cause negative effects on the native plant community, as demonstrated here in the rupestrian fields.

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The theoretical research of the study focused to business process management and business process modeling, the goal was to found a new business process modeling method for electrical accessories manufacturing enterprise. The focus was to find few options for business process modeling methods where company could have chosen the best one for its needs The study was carried out as a qualitative research with an action study and a case study as the most important ways collect data. In the empirical part of the study examples of company’s processes modeled with the new modeling method and process modeling process are presented. The new way of modeling processes improves especially visual presentation of the processes and improves the understanding how employees should work in the organizational interfaces of the process and in the interfaces between different processes. The results of the study is a new unified way to model company’s processes, which makes it easier to understand and create the process models. This improved readability makes it possible to reduce the costs that were created from the unclear old process models.

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This dissertation critically reviews the idea of meritocracy from both a theoretical and an empirical perspective. Based on a discussion of classical texts of social philosophy and sociology, it is argued that meritocracy as a concept for social stratification is best compatible with the sociological tradition of status attainment research: both frame social inequality in primarily individualistic terms, centring on the role of ascribed (e.g., gender, social background) and achieved (e.g., educational qualifications) characteristics for determining individuals’ socioeconomic rewards. This theoretical argument introduces the research problem at the core of this dissertation: to what extent can the individualistic conception of social stratification be maintained empirically? Fields of study and their interaction with educational attainment levels play a prominent role in the analysis of this question. Drawing on sociological versions of segmented labour market theory, it is assumed that fields of study may channel individuals into heterogeneous political-economic contexts on the labour market, which potentially modify the socioeconomic benefit individuals derive from their qualification levels. The focus on fields of study may also highlight economic differentials between men and women that derive from the persisting segregation of men’s and women’s occupational and educational specializations rather than direct gender discrimination on the labour market. The quantitative analyses in this dissertation consist of three research articles, which are based primarily on Finnish data, but occasionally extend the view to other European countries. The data sources include register-based macro- and microdata as well as survey data. Article I examines the extent and the patterns of gender segregation within the Finnish educational system between 1981 and 2005. The results show that differences between men’s and women’s field specializations have for the most part remained stable during this period, with particularly high levels of gender segregation observed at lower educational levels. The focus in Article II rests on the effects of gender-segregated fields of study on higher education graduates’ occupational status. It is shown that fields of study matter for accessing professional jobs and avoiding low-skilled positions in Finland: at the early career stage, particularly polytechnic graduates from female-dominated fields are less likely to work in professional positions. Finnish university graduates from male-dominated fields were more likely than their peers with different specializations to work as professionals, yet they also faced a greater risk of being sorted into lowskilled jobs if they failed to make use of this advantage. Article III proceeded to analyse the joint impact of educational qualification levels and fields of study on young adults’ median earnings in Finland between 1985 and 2005. The results show that qualification levels do not confer a consistent benefit in the process of earnings stratification. Advanced qualifications raise median earnings most clearly among individuals specializing in the same field of study. When comparing individuals with different field specializations, on the other hand, higher-level qualifications do not necessarily lead to higher median earnings. Overall, the findings of this dissertation reveal a heterogeneous effect of education for achieving social positions, which challenges individual-centred, meritocratic accounts of social stratification and underlines the problematic lack of structural and institutional dimensions in the dominant account of social status attainment.

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The objective of this thesis was to study the effect of pulsed electric field on the preparation of TiO2 nanoparticles via sol-gel method. The literature part deals with properties of different TiO2 crystal forms, principles of photocatalysis, sol-gel method and pulsed electric field processing. It was expected that the pulsed electric field would have an influence on crystallite size, specific surface area, polymorphism and photocatalytic activity of produced particles. TiO2 samples were prepared by using different frequencies and treatment times of pulsed electric field. The properties of produced TiO2 particles were examined X-ray diffraction (XRD), Raman spectroscopy and BET surface area analysis. The photocatalytic activities of produced TiO2 particles were determined by using them as photocatalysts for the degradation of formic acid under UVA-light. The photocatalytic activities of samples produced with sol-gel method were also compared with the commercial TiO2 powder Aeroxide® (Evonic Degussa GmbH). Pulsed electric field did not have an effect on the morphology of particles. Results from XRD and Raman analysis showed that all produced TiO2 samples were pure anatase. However, pulsed electric field did have an effect on crystallite size, specific surface area and photocatalytic activity of TiO2 particles. Generally, the crystallite sizes were smaller, specific surface areas larger and initial formic acid degradation rates higher for samples that were produced by applying the pulsed electric field. The higher photocatalytic activities were attributed to larger surface areas and smaller crystallite sizes. Though, with all of the TiO2 samples produced by the sol-gel method the initial formic acid degradation rates were significantly slower than with the commercial TiO2 powder.

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Kartta kuuluu A. E. Nordenskiöldin kokoelmaan

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The growing pharmaceutical interest, among others, in the polymorphic composition of the emerging solid end-products from production processes has been traced to the need for attainment of high product purity. This is more so as the presence of different polymorphs may constitute physical impurity of the product. Hence, the need for optimization of the yield of desired product component(s) through controlled crystallization kinetics for instance. This study was carried out to investigate the impact of pulsed electric field (PEF) irradiation on the crystal morphology of glycine obtained by cooling crystallization (without seeding) from commercial glycine sample in distilled deionized water solution. In doing so, three different pulse frequencies (294, 950 and 145 Hz) and a case without PEF were studied at three cooling rates (5, 10 and 20 ºC/h). The crystal products obtained were analyzed for polymorphic composition by powder x-ray diffraction (PXRD) and Fourier transform infrared (FTIR) spectroscopy while the particles characterization was done on Morphologi G3. The results obtained from this study showed that pulsed electric field irradiation had significant impact on metastability of the aqueous solution as well as on the polymorphic composition of the end product. With increasing PEF frequency applied, nucleation started earlier and the γ-glycine polymorph content of the product crystals increased. These were found to have been aided by cooling rate, as the most significant effect was observed at 5 ºC/h. It was also discovered that PEF application had no measurable impact on the pH of the aqueous solution as well as the size distribution of the particles. Cooling on the contrary was believed to be responsible for the broadening of the particle size distribution with a downward shift of the lower limit of the raw material from about 100 μm to between 10 and 50 μm.

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The design process of direct-driven permanent magnet synchronous machines (PMSMs) for a full electric 4 ´ 4 sports car is presented. The rotor structure of the machine consists of two permanent magnet layers embedded inside the rotor laminations thus resulting in some inverse saliency, where the q-axis inductance is larger than the d-axis one. An integer slot stator winding was selected to fully take advantage of the additional reluctance torque. The performance characteristics of the designed PMSMs were calculated by applying a twodimensional finite element method. Cross-saturation between the d- and q-axes was taken into account in the calculation of the synchronous inductances. The calculation results are validated by measurements.

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A direct-driven permanent magnet synchronous machine for a small urban use electric vehicle is presented. The measured performance of the machine at the test bench as well as the performance over the modified New European Drive Cycle will be given. The effect of optimal current components, maximizing the efficiency and taking into account the iron loss, is compared with the simple id=0 – control. The machine currents and losses during the drive cycle are calculated and compared with each other.

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Findings by our group have shown that the dorsolateral telencephalon of Gymnotus carapo sends efferents to the mesencephalic torus semicircularis dorsalis (TSd) and that presumably this connection is involved in the changes in electric organ discharge (EOD) and in skeletomotor responses observed following microinjections of GABA A antagonist bicuculline into this telencephalic region. Other studies have implicated the TSd or its mammalian homologue, the inferior colliculus, in defensive responses. In the present study, we explore the possible involvement of the TSd and of the GABA-ergic system in the modulation of the electric and skeletomotor displays. For this purpose, different doses of bicuculline (0.98, 0.49, 0.245, and 0.015 mM) and muscimol (15.35 mM) were microinjected (0.1 µL) in the TSd of the awake G. carapo. Microinjection of bicuculline induced dose-dependent interruptions of EOD and increased skeletomotor activity resembling defense displays. The effects of the two highest doses showed maximum values at 5 min (4.3 ± 2.7 and 3.8 ± 2.0 Hz, P < 0.05) and persisted until 10 min (11 ± 5.7 and 8.7 ± 5.2 Hz, P < 0.05). Microinjections of muscimol were ineffective. During the interruptions of EOD, the novelty response (increased frequency in response to sensory novelties) induced by an electric stimulus delivered by a pair of electrodes placed in the water of the experimental cuvette was reduced or abolished. These data suggest that the GABA-ergic mechanisms of the TSd inhibit the neural substrate of the defense reaction at this midbrain level.

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The objective of this thesis was to study the effect of pulsed electric field on the preparation of TiO2 nanoparticles via sol-gel method under the visible light irradiation. The literature part introduces properties of different TiO2 crystal forms and principle of photocatalysis. It was expected that pulsed electric field would have an influence on degradation for oxalic acid and formic acid. TiO2 samples were prepared by using three frequencies (50Hz, 294Hz, and 963Hz) and two treatment times (12 minutes and 24 minutes) of pulsed electric field. The photocatalytic activities of TiO2 samples produced with sol-gel method were also compared with the TiO2 particles made by previous study and with the commercial TiO2 powder Aeroxide® (Evonic Degussa GmbH) at the same condition. Results show that pulsed electric field does have an effect on degradation for oxalic acid and formic acid. Generally, higher photocatalytic activities for oxalic acid and formic acid were obtained with lower frequency and longer treatment time of pulsed electric field.

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This study proposes alternatives to the current methods of processing round-cooked lobster. The paralyzation of lobsters with direct electric shock consumes 10.526 x 10-3 kWh, which is significantly less than the 11 kWh required by the traditional thermal-shock method (based on 60 kg of lobsters). A better weight gain was obtained by immersion of paralyzed lobsters in brine before cooking. Systematic trials combining 3, 6, or 9% brine concentrations with immersion periods of 15, 30, or 45 minutes were performed in order to determine the best combinations. A mathematical model was designed to predict the weight gain of lobsters of different sizes in any combination of treatments. For small lobsters, a 45 minutes immersion in 6% brine gave the best response in terms of weight gain (4.7%) and cooking produced a weight loss of only 1.34% in relation to fresh lobster weight. For medium-sized lobsters, a 45 minutes immersion in 9% brine produced a weight gain of 2.64%, and cooking a weight gain of 1.08%. For large lobsters, a 45 minutes immersion in 6% brine produced a weight gain of 3.87%, and cooking a weight gain of 1.62%.

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The application of VSC-HVDC technology throughout the world has turned out to be an efficient solution regarding a large share of wind power in different power systems. This technology enhances the overall reliability of the grid by utilization of the active and reactive power control schemes which allows to maintain frequency and voltage on busbars of the end-consumers at the required level stated by the network operator. This master’s thesis is focused on the existing and planned wind farms as well as electric power system of the Åland Islands. The goal is to analyze the wind conditions of the islands and appropriately predict a possible production of the existing and planned wind farms with a help of WAsP software program. Further, to investigate the influence of increased wind power it is necessary to develop a simulation model of the electric grid and VSC-HVDC system in PSCAD and examine grid response to different wind power production cases with respect to the grid code requirements and ensure the stability of the power system.