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3151 Uppsatser om Power-loss - Sida 1 av 211

Faktorer som påverkar vindkraftsutbyggnaden

Wind power is expanding rapidly in Sweden. Increasing amounts of wind power sets higher requirements on balancing power and grid expansions and would affect the whole Swedish electricity system. The aim of this report is to examine the factors affecting the wind power expansion in Sweden. How many wind power plants projects will obtain building permissions and what costs and revenues can be expected? How much balancing power will be required and does a changing geographical distribution of the wind power plants reduce the need of balancing power?A survey of the county board?s official applications has been made and out of all the applications, corresponding to 80 TWh produced per year, about half of the applications are expected to obtain a permit with a major portion of them located in the north of Sweden.Especially older wind power plants, deriving revenue from Nord pool, find themselves today in a complicated financial situation.

Spänningsstyrd underfrekvenslastfrånkoppling i elektriska kraftsystem

This report is a Master?s Thesis performed by Andreas Adolfsson and David Jacobsson atChalmers University of Technology. The purpose of this master?s thesis is to evaluate anew method for load-shedding, the voltage controlled underfrequency load-sheddingdeveloped by ABB. This report presents a comparison between conventionalunderfrequency load-shedding and this new method for load-shedding.

Trafikverkets effektstyrningssystem - EFS 132 kV : Bidraget till minskade förluster

The technological legacy from the early electrification of the Swedish railroads has resulted in a power grid with a lower grid frequency than the national power grid from which it is fed. Energy transfer between these power grids with different frequencies requires substations, adapting the grid frequency for the rail road power grid. For this purpose, a feeding power grid has been built, stretching across the country from Boden in the north to Tälle/Häggvik in the south.Power transfer in the Swedish power grid results in voltage angle differences which increase with increasing loads and transfer distance. These voltage angle differences are transferred from the power feeding substations to the rail road power grid, will in some extent cause loss of energy due to unwanted power flows from north to south.To minimize the losses due to this phenomenon, a power management system called EFS 132 kV has been developed and implemented. The system minimizes the unwanted power flows and controls the desired power flow for a good distribution of loads between the power feeding substations.This thesis investigates the extent of the transmission losses avoided due to the EFS 132 kV that coordinates the idling angles to a common reference point.The results indicate that EFS 132 kV affects the power flow, especially between the northern substations through an improved load distribution.

Barn med 22q11.2 deletionssyndromet ? hur hör de?

The 22q11.2 deletion syndrome is a common genetic disorder that affects for example the heart, palate, immune system and hearing and therefore affects a child?s development. The purpose of this study was to investigate the proportion of children (0-18 years) with 22q11.2 deletion syndrome who have a hearing loss. A retrospective study of 103 children diagnosed with 22q11.2 deletion syndrome was conducted by medical records. Of the 103 children, 51 were boys and 52 were girls.

Wool loss in sheep

The idea behind this project came from a feed study executed two years during the lambing season. Both years wool loss was experienced. Low temperature in combination with shearing was believed to cause the wool loss the first year, while protein deficiency was believed to be the cause the second year. In the literature many causes of wool loss are described; mechanical wear, telogen effluvium, bacterial dermatitis, external parasites, wool break, scrapie, genetic causes and nutritional deficiencies are some examples. The aim of this thesis was to study causes for wool loss and how common wool loss is in Swedish sheep herds.

Mätsystem för effektförluster i en högfrekvenstransformator

To measure losses in a transformer with today?s methods is either slow or insecure. There s a new method developed by Alstom that hasn't been actualize in to a test-system and that has been the assignment in this project. The idea is built on a switched system and a CLR- circuit in the resonant frequency. The test-system has a calculated Power-loss that make the efficiency to be as high as 99,8% and in reality over 95%.

Att förlora sitt vuxna barn : En kvalitativ studie om hur fem mammor upplever och hanterar sina vuxna barns död

The purpose of this study was to examine how five mothers experience and cope with theloss of their adult children and also how this loss affect the mothers. We chose a qualitativemethod using semistructured interviews. We used Lazarus and Folkman?s coping theoryand Folkman?s revised coping theory in our analysis. The results showed that the mothers?experiences were very individual.

Vilka strategier och metoder kan vara användbara för en hållbar viktnedgång?

The purpose of the study was to examine what methods and strategies individuals use to maintain their weight loss. Another aim was to explore which factors can complicate or simplify weight loss maintenance. Fifty-four individuals who had maintained their weight loss more than a year, participated by answering a questionnaire. The questionnaire was constructed and distributed through the internet. The answers were registered in the program google docs.  The participants mentioned successful methods and strategies, such as exercising regularly, the majority exercised 30 minutes at least five times per week.

Hörselnedsättning hos för tidigt födda barn ? En litteraturstudie

A stay in the neonatal intensive care unit of greater than 5 days is one of the identified risks ofa sensorineural hearing loss. Preterm infants usually have at least one risk factor for hearingimpairment. The period from 25 weeks' gestation to 5 to 6 months of age is most critical tothe development of the auditory system. We think it is important to investigate hearingimpariment among infants born preterm, degree and type of hearing loss, risk factorsassociated with hearing loss and how the auditory system may be affected by preterm birth.ObjectiveA critical review of the current literature including studies of preterm infants born betweengestonal age 25-37. Our aim is to identify the most common type and degree of hearing lossamong infants born preterm and if there is an association between hearing loss and pretermbirth.MethodA literature search of Scopus and Pubmed resulted in 16 articles from 2000-2015ResultsMost of the infants in this study had a severe to profound sensorineural hearing loss.

Hållbar vattenkraft i Nissan : En förstudie och konsekvensutredning över förutsättningarna för ökade vandringsmöjligheter med nya fiskvägar.

The hydropower from Nissan River is of national interest and produces annually 230 GWh from the twelve power stations in the main flow. For modified waters a consideration between the power production and the biological values has to be made. This reports serves as a pre-study for Nissans Vattenråd. It tries to evaluate some of the biological values in the Nissan basin and map the power production in the area. And the size and value of lost power production from new fishways for the twelve stations in the main flow.The investment of new fishways is calculated using simplified templates with values from the business.

Beteende inför lek hos odlad respektive vild lax (Salmo salar L.) i Klarälven

In many regulated rivers, authorities have stocked hatchery salmon to compensate for loss of wild populations. However, hatchery fish have not always behaved as wild fish do, and stocking them has not always fully compensated for the loss of wild fish. The purpose of this study was to compare swimming behaviour in the river before spawning, the choice of spawning areas and body size between wild and hatchery-reared salmon in the river Klarälven. Salmon behaviour in the river before spawning was analyzed using radio telemetry. The salmon were caught at Forshaga power plant, radio-tagged and returned to Klarälven at Ekshärad, 107 km from the river?s mouth.

Beräkning av värmeförluster och energieffektivisering av elbussar

The ?civilized? world is in need of fossil fuel in order to function. Hybricon AB is a company in Umeå that is developing a technology that hopefully can reduce parts of this need. They are currently testing their two electrical busses (with Hybrid backup) in city traffic on the roads of Umeå in cooperation with the county of Umeå.                               The busses are originally diesel-busses, but the diesel motor has been replaced with two electrical hub-motors with a power of 145 kW each that are powered by batteries.The batteries are charged at the end station after each route. In case the batteries should run low on capacity during driving, they can be recharged by the so called genset.

Kartläggning av allmänhetens attityd till hörselnedsättning och självskattad kunskap om hörsel ? en enkätundersökning

Objective: 1.4 million people in Sweden state that they are having problems with hearing and the majority havehad no contact with the hearing rehabilitation services. To have a hearing loss seems to be associated withseveral negative attributes. This could be due to bad attitude and insufficient knowledge on hearing loss intoday?s society.Purpose: The purpose with this study was to map the adult populations attitude towards hearing loss and selfratedknowledge of hearing with a survey.Methods: A web survey was made for this study. An official link to the survey was shared from two Facebookaccounts to a total of 997 contacts and a total of 247 responses were collected.Results: The majority of the respondents have estimated their general knowledge of hearing to fairly extensivefollowed by very small.

Hörselnedsättning bland diabetiker med typ 1-diabetes respektive typ 2-diabetes ? en jämförande metaanalys

Background: Diabetes mellitus is one of today's major public health problems, affecting up to 347 million people worldwide. Several studies have shown a correlation between hearing loss and diabetes mellitus. However, it is still unclear whether this correlation differs between type 1-diabetes and type 2-diabetes.Purpose: The purpose of this study is to investigate whether there is any difference in prevalence of hearing loss in type 1-diabetics versus type 2-diabetics.Method: A meta-analysis was performed based on ten studies that were identified through the database PubMed and through manual searching of references. Odds ratios for the risk of developing hearing loss were calculated in each study. Pooled odds ratios were calculated using a random effects model.Results: Pooled odds ratios indicates that both type 1-diabetics and type 2-diabetics are more likely to develope hearing loss compared to non-diabetic controls.

Pengar, press & partiledare : En studie om porträtteringen av makt i svenska tidsskrifter

We have studied how power is portrayed in Swedish journals by analyzing eight portraits of Swedish persons with economic or political power. We have studied how they and their power are described by the journalist in text and picture. We wanted to see which picture the journalist shows of people with power, what properties they are given by the journalist and how this picture is shown by the texts and the pictures. We have also looked if there are any differences between people with political power and people with economic power. We have under our studies noticed that the persons with power are described as very successful and special and this picture are shown in a very clear and unproblematic way..

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