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695 Uppsatser om Frequency - Sida 5 av 47
Factors affecting bark-stripping by red deer (Cervus elaphus) : the importance of landscape structure and forage availability
Bark-stripping by red deer (Cervus elaphus) cause extensive damage to economically valuable spruce trees (Picea abies) in Swedish forests. The underlying causes for bark-stripping are not fully understood, and the Frequency and severity of damage unpredictably differ between regions. In this study, I investigated if landscape structure (e.g. agricultural dominated landscape opposed to forest dominated landscape), forage availability, population density and disturbance (e.g. roads and settlements) affect bark-stripping Frequency.
Utredning av frekvensregleringens påverkan på mekanisk utrustning i en kaplanturbin
As a consequence of increasing wind power installations in the Nordic grid the last years, the need for regulating power has become larger. In the Nordic grid, regulating power is mainly provided by hydro power. One part of the regulating power is called Frequency control, which ensures that the grid Frequency is stable and close to 50 Hz.However, setting the turbine into Frequency controlled operation may cause stress and wear of the components in the mechanical control system. Frequency controlling implies large and frequent servo forces and longer travelling distance of the sliding bearings in the Kaplan turbine.Based on one selected Kaplan turbine, Selsfors G1, measurements and MATLAB calculations have been performed in order to determine forces and movements of the linkage system. With these forces and movements as input, stresses and fatigue have been determined as well as sliding distances, bearing pressures and wear of bearings during a typical lifetime of 40 years.The results indicate that no severe wear exists on the bearings during 40 years of service.
Vindfällning i naturliga och skapade bryn och kanter :
The aim of this work was to study if the edge of the forest is more resistant to heavy winds than the trees located further in from the edge, and how this edge effect changes between different types of tree species and site types.
The data was collected from an electric power line going from the north to the south of
Sweden. The mean value of the clearcutted area around the power line was 120 meters. The
main direction of the storm in January 2005 was west-southwest and thus the power line was a perfect place for gathering a large data set.
The main parameter studied was the damage Frequency at the edge of the forest compared to
the trees located further in from the edge (up to 100 m from the power line). Tree species mixture, soil moisture class, soil type, topography, stand height, stand height of the stand on the other side of the power line and wind exposition was estimated.
The results showed a distinct edge effect. The edge of the forest had clearly lower damage Frequency for all tree species.
A marked difference was observed between tree species and damage Frequency.
Åt var och en efter behov? Kriminalitet som markör för olika behandlingsalternativ
The aim of this study was to, using previously collected data from self-declared antisocial behaviour questionnaires, examine if the crime Frequency has been different between adolescents that have either been referred to two different forms of open care in social service, child and youth psychiatric inpatient care or have been sent to Homes for Specialised Supervision. The criminality Frequency and the most common crimes committed were compared between the study groups and further between genders in each particular study group. Statistical significance testing was used and the results of the survey revealed that juvenile delinquents that had committed severe criminal acts were represented in all four groups. The study group with adolescents in national care was the most different from other groups. These youths seemed to have had a lower crime Frequency than the other groups with the exception assault and robbery.
Trådlös energiöverföring via elektromagnetisk induktion
This paper describes a method for wireless energy transfer via near-field electromagnetic inductionthat is inexpensive, simple and can be applied to almost any type of system, regardless of size andenergy demands.The method uses a primary unit consisting of an oscillator, amplifier and inductive coil thattransfers energy to a secondary unit consisting of a coil, rectifier and voltage regulator. Two typesof oscillators and several amplifier designs were realized and evaluated together with a multitudeof flat coils of both monofilar and bifilar type.The results show that it is important to use an oscillator whose Frequency is dependent on theinductance of the connected transmission coil, such as the Colpitts oscillator. This is preferable toan oscillator with a preset Frequency, such as a Schmitt-trigger oscillator..
Svansbitning hos grisar, arv eller miljö?
Tail-biting in pigs is an animal welfare issue and in Sweden during 2002 the producers lost tree million Swedish crowns because of tail biting. This economic loss depends on the pigs which are discarded at slaughter because of tail biting. Tail biting can be separated into two stages, "pre-injury" and "injury". The aim of this study is to investigate if tail biting depends on environment or genetic background.A lot of research on the environments effects on the behaviour of pigs but not so much on the genetic effects has been performed. The Frequency of tail biting in pig farms influence among others of environment enrichment, ventilation, gender and breed of the pig.
Beteenden hos geparder i två stora svenska djurparker
Cheetahs in the wild are declining due to hunting, lack of prey, exploitation of habitats and loss of cubs to predators. Those are the main reasons to why cheetahs are kept in captivity today for conservation. Many cheetahs kept in captivity are seen pacing ? a behaviour that arise when the animal is prohibited from performing natural behaviours. It is believed to being attributed to a lack of stimulation in the environment where they are being held.
Anläggningsmaterial för landskapsarkitekten ur miljösynpunkt
Tail-biting in pigs is an animal welfare issue and in Sweden during 2002 the producers lost tree million Swedish crowns because of tail biting. This economic loss depends on the pigs which are discarded at slaughter because of tail biting. Tail biting can be separated into two stages, "pre-injury" and "injury". The aim of this study is to investigate if tail biting depends on environment or genetic background.A lot of research on the environments effects on the behaviour of pigs but not so much on the genetic effects has been performed. The Frequency of tail biting in pig farms influence among others of environment enrichment, ventilation, gender and breed of the pig.
Ulla Molin - Östbergs trädgård i Lund
Tail-biting in pigs is an animal welfare issue and in Sweden during 2002 the producers lost tree million Swedish crowns because of tail biting. This economic loss depends on the pigs which are discarded at slaughter because of tail biting. Tail biting can be separated into two stages, "pre-injury" and "injury". The aim of this study is to investigate if tail biting depends on environment or genetic background.A lot of research on the environments effects on the behaviour of pigs but not so much on the genetic effects has been performed. The Frequency of tail biting in pig farms influence among others of environment enrichment, ventilation, gender and breed of the pig.
Jämförelse mellan ?Auditory Brainstem Response (ABR) och ?Auditory Steady State Response? (ASSR) för att uppskatta hörtrösklar på barn i narkos. Kan testtiden minska om 500 Hz utesluts vid ASSR-mätning?
ObjectiveThe objective of this study was to investigate the clinical application to use ASSR in anesthetized childrenDesignOne main ambition of the investigation was to compare hearing threshold using ABR with estimated hearing threshold using ASSR. Another aim was to examine if the duration of an ASSR measurement could be reduced by only using the frequencies 1, 2 and 4 kHz and exclude the Frequency 0.5 kHz. This is a retrospective study using electrophysiological measurement from a database.ResultResults showed a high correlation between hearing threshold using ABR and estimated thresholds using ASSR, with the Frequency 0.5 kHz showing a slightly lower correlation. Result also showed that the test duration was increased when using all test frequencies in ASSR-measurement compared to when 0.5kHz was excluded. ConclusionThe study showed a high correlation when comparing hearing threshold using ABR and ASSR.
Förekomst & kostnad av kapsprickor i stormaskadad skog
The aim for this study where to investigate the Frequency of cutting cracks in saw timber harvested in the storm-damaged forests in regions where the storms Hilde and Ivar hit. The idea for this work came from one of the region?s biggest actors, SCA Skog and Jämtlands district. The purpose where to find out how big proportion of the saw timber that contains cutting cracks, their financial cost in lost wood value and also give advice and suggestions on how to work against the Frequency of cutting cracks.
For the field-study some guidelines where used to make sure that the samples were taken under the same conditions, they were:
? The field-study must be performed under harvesting of storm-felled forest, which are horizontal/inclined trunks.
? The averaged sized tree will make it possible to harvest saw timber.
? The trunks can?t be root cut.
A methodology called in Swedish ?Trissmetoden? was used because it is the most frequent used methodology in earlier performed studies and the only one that can be used I field.
Under the field-study data were collected from 570 saw timber logs, 30 logs from each one of the tested harvesters.
En studie om vad som behövs för att skolträdgårdar skall fungera under en längre tid : en utvärdering av Edane skolas skolträdgård
Tail-biting in pigs is an animal welfare issue and in Sweden during 2002 the producers lost tree million Swedish crowns because of tail biting. This economic loss depends on the pigs which are discarded at slaughter because of tail biting. Tail biting can be separated into two stages, "pre-injury" and "injury". The aim of this study is to investigate if tail biting depends on environment or genetic background.A lot of research on the environments effects on the behaviour of pigs but not so much on the genetic effects has been performed. The Frequency of tail biting in pig farms influence among others of environment enrichment, ventilation, gender and breed of the pig.
Marknadsundersökning av Claas Lexion tröskor : kapacitet och kundnöjdhet
LEXION is the name of the largest series of combines made by the CLAAS factory in
Germany. LEXION was introduced on the Swedish market 1996 and was for sale in Sweden
from 1997. LMB have sold over 400 LEXION-combines in Sweden.
In cooperation with the Swedish general agency we decided to make a market research on the
Swedish LEXION-market. The questionnaire was supposed to give answers about capacity
and technical equipment.
Before I made the questionnaire I studied manuals and combines.
I got 81 answers of about 325 questionnaires. That makes 25 % reply Frequency.
MPD-vågformer för helikopterradar
A helicopter based system equipped with a millimetre-wave fire control radar is studied for improvement of the detection probability for moving ground targets. The system is a pulse doppler radar that sends out the electromagnetic wave in repetitive pulses. The Frequency in which radar sends this pulse is called Pulse Repetition Frequency (PRF). The velocity of the moving targets is measured by spectral analysis of the pulses received. With this sort of system some targets will not be possible to detect.
RCC-Jordfelsskydd, mätmodul för övertonsanalys
The majority of all power cuts that affects individuals and communities are caused by earth faults on the power transmission lines at 10kV and 20kV level [1]. If these power cuts could be eliminated, less disturbances and interrupts would lead to large amounts of money savings.Swedish Neutral has developed such a protection system. When an earth fault occurs power is injected into the neutral point of the transformer. The RCC (Residual Current Compensation) protection calculates a compensation current exactly 180 degrees out of phase to the fault current. Doing this, the voltage at the fault location becomes very close to zero, without affecting the power transmission.The protection system can only compensate automatically for the fundamental Frequency (50Hz), and manually for the 3rd, 5th, 7th and 9th harmonics.