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698 Uppsatser om Frequency inverter - Sida 14 av 47

Mätningar och analys av elnätet hos FHP, Basproduktion

This report is a degree project performed at Freudenberg Household Products AB, (FHP). The degree project comprises measurement and analysis of the power net at FHP Basproduction. The content is divided between one theory-part, one document- part with measurements and also conclusions and a list of measures to be taken. During the project the purpose and restriction change from a quality investigation to only concentrate on harmonics and finding the reason why they exist, and also to find a solution to the problem with harmonics. The measurements shows that the power net contains harmonics of different order and intensity.

Bedömning av utländsk brytning och förståelighet hos personer med svenska som andraspråk före och efter en kurs i svenskt uttal

There is a lot of research made on second language (L2) learning (Jesney, 2004). However the relationship between foreign accent, intelligibility and acoustics within pronunciation tutoring is quite an unresearched area (Thorén, 2008). The aim of the study was to analyze how a course in Swedish pronunciation affected foreign accent, intelligibility and acoustics among L2-learners of Swedish. A total of 41 people participated in the study: 16 L2-learners, 4 native Swedish speakers consisting a control group and 21 perceptual assessors with Swedish as native language. The L2-learners foreign accent and intelligibility were rated by the listeners before and after a course in Swedish pronunciation on an eight-point Likert-scale.

Design av stimuligenerator för radarmålsökare

During the development of microwave based sensors such as radar target seekers, input signals are needed to verify the performance of the system. Therefore, a channel board has been developed by previous thesis projects at Saab Bofors Dynamics. It uses a technique called Digital Radio Frequency Memory (DRFM). The purpose of this board is to sample and digitally store radio frequency signals in order to reconstruct them after a certain delay.The aim of this thesis project was to use the channel board named above to construct a portable instrument for generation of stimuli signals. This assignment has been divided into two tasks: firstly, to construct and put together the hardware components and secondly, to implement a graphical user interface for the instrument.

Aktiv bullerdämpning i ventilationssystem

Active headsets have been on the market for years and now it is time for something else to enter the stage. The technology of active noise reduction can for exmple also be used in ventilation systems for reducing ventilation noise. An active control system principally consists of four important components, namely the downstream error microphone, the upstream detection or reference microphone, the digital signal processor (DSP) and a loudspeaker. The upstream reference microphone listen to the primary ventilation noise and sends it to the DSP which makes a phase shift to the signal and sends it to the loudspeaker. The loudspeaker sends out the opposite waveform of the incoming one and reduce the primary ventilation noise.

Effektiviseringspotential inom industrisektorn : Energibesparing vid frekvensstyrning av centrifugalpumpar ? en fallstudie

The project was performed at SiemensIndustry Drive Technologies with theobjective to provide actual values forthe energy savings potential withinSiemens scope of practice.In Sweden the electrical drives standfor about 30 % of the total electricityconsumption and about 60 % of theelectricity consumption within theindustry. During the pre-study phaseelectrical drives with pump applicationswere identified as large energy users.Because of this a case study at one ofSiemens customers, Stora Enso Fors wasperformed. The system that was evaluatedduring the case study was a throttledsystem with a centrifugal pump forpumping pulp.The results yielded that a saving ofover 50 % could be achieved by replacingthe throttle valve with a variable speeddrive, a frequency converter. Thepayback period was two years and twomonths and the present value for thetotal life cycle cost of the variablespeed system was 662.566 SEK lower thanfor the throttled system. As aconsequence, Stora Enso Fors is advisedto invest in a frequency converter forregulation of the system.The general conclusion is that a focuson system efficiency is the mostimportant factor in energy efficiencyprojects and that the system regulationmethod has a large impact on the overallsystem losses and hence its efficiency.Energy efficiency potential forthrottled systems with centrifugal pumpsis large and significant economicalsavings can be made through investmentswith short payback time..

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.

Orsaker till kalvningssvårigheter och dödfödslar hos SLB och SRB

Difficult calvings and stillborn calves are costly for the producer and lowering these frequencies can decrease the costs for the dairy operation. Each calving in the herd is registered by the farmer and stored in a central database. The information is used to monitor the level of calving-difficulties and stillborn calves in the herd and nationally. Monitoring of these registrations is important to detect possible changes. Breeding-value prediction for calving traits is based on the calving information in the database.

Analys av PWM-mönster i Matlab

One of ABB Power Systems´s business areas is HVDC (High Voltage Direct Current) technology. HVDC is used for transmissions for both short and long distances. One of Power Systems?s products is called HVDC Light. HVDC Light is a relatively new technology for power transmission, but have before only been used for motor drives applications.

Analys av Husqvarna AB:s lastbilstransporter till Italien

The thesis has been written as a part of the Bachelor degree in Industrial engineering and management at the School of Engineering in Jönköping. The work is focused on the part of Husqvarna AB?s supply chain that is associated with the lorry transports to Italy. Husqvarna AB has approximately ten Italian customers, whose delivery patterns have been studied from January 2007 to July 2008. Some of the customers have a low delivery frequency and small amounts of goods that they therefore have not been fully analyzed in this report.

Reducering av effektförbrukning i inbyggda system med Linux

Linux is a growing operating system in embedded systems. Today, Linux is not only in heavy servers but also in cell phones, PDAs, cameras and other devices running on battery power. While current technology is more energy efficient, more and more technologies are implemented into a single unit resulting in an overall increase of power consumption.Low power consumption is an increasingly important feature of a system today. Lower power consumption means lower costs, less environmental impact, and longer life for applications that runs on batteries.This work compiles methods to reduce power consumption of Linux systems. The work includes examining whether the available opportunities are platform-specific or of a more general nature.

Effect of low light intensities on dairy cows? behavior

The animal welfare act in Sweden states that dairy cows need to have at least a dim light present at night, but there are no recommendations for what intensity the light should have. It is unknown how cows perceive and react to low light intensities and earlier studies on this topic are limited. Red light as night light has also been suggested, based on the cows? inability to perceive red light. This have however been questioned. The aim with this study was to investigate how four different light intensities affect dairy cows behavior.

The effect of rapeseed oil and palm oil supplement and milking frequency on milk yield and milk fat quality

Milk fat is an important feature in many different milk products and other foodstuffs and it is often crucial for the dairy plants that the milk fat is stable for different manufacturing processes. Lipolysis is the enzymatic degradation of fat and is the one of the causes for an elevated amount of free fatty acids (FFA) in milk. Further, the change in fatty acid (FA) composition in milk can affect the stability of the product and also the manufacturing process. Both internal and external factors, at farm level or at the dairy plants can affect both FA composition and content of FFA. Milking frequency (MF=number of milkings per cow and day) and the composition of feed are two examples of factors generally performed at farm level. The objective of the present study was to evaluate how FA composition of milk and amount of FFA are influenced by two different ingredients supplemented to concentrate.

Statistisk kartläggning av dimma längs E4:an mellan Helsingborg och Jönköping

Fog is a small-scale weather phenomenon that are fascinating to people. However, the presence of fog in road traffic reduces the visibility and increases the risk of road accidents. By the Swedish Road Weather Information System (VViS), the safety on roads could ameliorate and road accidents caused by fog and other weather hazards could be prevented. Fog is however a complex and usually local phenomenon, why fog formation generally is not easy to predict. For that reason, a statistical mapping of fog, especially along a motorway with high traffic volumes, could be useful in planning to prevent road accidents.

Kraftig anemi hos tax :

The Clinical Pathology Laboratory at SLU in Uppsala has analysed several blood samples from Dachshunds with severe anemia. As there are no previous studies on this topic, a study was performed to evaluate if Dachshunds are more prone to severe anemia compared with other breeds. In addition, a retrospective case study on Dachshunds with severe anemia was done to search for common risk factors or diseases. Hemoglobin values in samples from 1272 Dachshunds and 2269 German Shepherds analyzed from September 1994 to October 2007 were used to compare the frequency of severe anemia in Dachshund and German shepherd. The samples were identified by laboratory information system.

Det gör ont när stockar spricker!

The aim of this study was to provide SCA Forest Norrbotten District with material to assist in their work towards decreasing the frequency of bucking splits in their saw timber logs. SCA Forest supplies the Munksund sawmill with pine timber. Periodically the sawmill experiences problems related to bucking splits in their logs. The purpose of this study was to find an available method to measure the occurrence of splits directly on incoming timber. The ambition was also to gain some knowledge about possible variations between different logging crews in terms of split frequency. If possible, this information could be used to investigate if certain crews produced more splits than others, and thereby making it possible to provide feedback to the logging machine operators. The study consisted of two major parts, a literature review, and a practical sawmill study.

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