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629 Uppsatser om Voltage measuring - Sida 12 av 42
Uppföljning av elevers läsutveckling
Utbildningsförvaltningen fattade 2003 ett beslut om att alla lärare i Stockholm skulle använda mätinstrument för bedömning av elevers läsutveckling. Syftet med denna uppsats är att granska och jämföra de två vanligast förekommande mätinstrumenten i Stockholmsområdet. De båda mätinstrumenten finns beskrivna i böckerna Nya Lusboken och God läsutveckling. En diskursanalys av de båda mätinstrumenten har gjorts och skillnader dem emellan har därigenom kunnat påvisas. Den största skillnaden är författarnas syn på fonologisk medvetenhet.
Dämplindningens inverkan på spänningens kurvform i en vattenkraftsgenerator
Harmonics are a well-known problem that has to be dealt with in the design of thegenerator. Internationally accepted standards limits the amount of harmonics allowedin the no-load voltage. These limits can be difficult to fulfill with integral slot winding,where the number of slots per pole and phase is an integer. The presence of thedamper winding often makes the problem with harmonics even worse and harmonicswith frequencies of order 6q±1 arise with significant amplitude. How the damperwinding is designed affect the content of harmonics in the no-load voltage and the aimwith these ? has been to investigate in which extent design of the damper windingaffects the contents of harmonics.Simulations with the 2-D finite element method have showed that if the damper barsis centered in the pole shoe, the amplitude of the harmonics of order 6q±1dependsboth on the ratio between the stator slot pitch and damper bars slot pitch and if thedamper bars are connected between the poles or not.If the damper bars is displaced with ¼ stator slot pitch alternately, the amplitude ofthe harmonics of order 6q±1 is reduced and the influence of the ratio between thestator slot pitch and the damper bars slot pitch will vanish.
Analys av linjetaxering i samband med gallringsinventering med avseende på kvalitet, tillförlitlighet och framtida utformning
Modern forest owners are very familiar with forest management and forest economics. Therefore they have high demands for quality in forest operations. Guarantee of quality in the shape of self-checking activities is an important tool to guarantee a well managed forestry operation. To meet the forest owners? demands on guarantee of quality and the entrepreneurs wish of an easy method for self-checking, the forest owners association, Södra skogsägarna, has developed a new method for thinning inventory.
The purpose of this study is to evaluate the method that is used for self-checking and to find ways to develop and improve of the method.
The data has been collected by inventory in a number of stands with circle-area survey and with strip survey, which is method that is used for self-checking.
The results show that the strip survey does not diverge more than ±10 % in measuring values of basal area, number of stems, roads share, thinning quotient, outtake of basal area and total volume compared to circle-area survey.
Utvärdering av förbättrad metod för objektiv kvalitetsbedömning av spermiemotilitet hos hingst :
In this trial we used QualispermTM as an objective method of measuring stallion semen.
Samples of semen were analyzed before and after centrifugation. Motility and concentration
were statistically analyzed. During the trial all the objective mesaurments were compared to a
subjective method.
The advantages of QualispermTM compared to older CASA- systems is it´s ability of
measuring a greater amount of spermatozoa while it also grades them into different
subpopulations. These subpopulations have different qualities that decides their capacity of
fertilization.
The results showed that this objective method might be used practically. Although, there are
still some disadvantages, such as high costs and the necessarity of accurat training of the
handler.
If it´s possible to prove further relevant results that also are statistically correct, this could
prove the usefulness of QualispermTM as an objective measurment method in the daily work
at gestuts and stallion stations, thus giving the staff a reliable instrument in assisting the work
for an improved horse breeding in Sweden, improving both in quality and economically..
Analys av spänningsstabilitetsberäkningar i det svenska elsystemet
Numerical simulations play a vital role in both static and dynamic stability assessment of electric power systems and the foreseeing of voltage collapse. Simulations performed by Svenska Kraftnät(SvK) are mainly done in the specialized voltage collapse predicting software tool, SPICA and the more all?purpose software tool, ARISTO.The grid operators at SvK use SPICA to predict the maximum transfer limit at specified sections (in this report the section in concerns is the southern part of Sweden i.e. interface1 4). SPICA is mainly used as an online application by using actual states from the grid, these states update every quarter of an hour.This thesis is a continuation of the master thesis SPICA ? ARISTO JÄMFÖRELSE by Jakob Katzman and Johan Fält.
Balis trädgårdar
The urbanization of the world is increasing. How it affects bird populations have been well studied during the last decade, and comparisons between urban and non-urban habitats have been carried out. A common method for measuring habitat quality is to calculate the population density. This method is easy to use, but have been criticized during the last couple of years. In this study, data of population densities was compared with data on reproduction success.
Att studera validerade mätinstrument : för att mäta barns oro inför dagoperation
Background: Anxiety with children before surgery is well known. From the 1950s there are various assessment instruments. Despite that most day surgery units offer preparation for children and parents, there are many children who exhibit a strong anxiety the day of surgery, which can lead to postoperative behavioral changes. Today the nurse estimates the anxiety of a child on personal experience and knowledge, forming the basis for estimation whether the child is in need of sedation or not. The purpose: of this study was to evaluate instruments that the nurse can use in measuring the degree of anxiety of children before fast clinical settings, such as day surgery.
Utvärdering av laddningskoncept för lastbilsbatterier
When drivers overnight in the truck lots of electric energy is consumed by heaters, fans, lights and other extra equipment. If the engine is not running, this energy is taken from the lead/acid batteries of the truck which then needs to be recharged during operating hours. The fact that the charge acceptance of the lead/acid batteries is dependent on the temperature makes it hard to fully recharge the batteries at lower temperatures. A negative charge balance can lead to starting problems within a few days use in cold climate.In this thesis work, the effects of different battery charging concept are evaluated on the most common Scania battery (175Ah). A battery model is implemented in Matlab and some simulations of charging are made.
Energikartläggning hos RostiGP i Gislaved
In today?s modern age, energy consumption has become a major issue, both from an environmental viewpoint and cost perspective. Because of a rapid technologic change and increased costs of production of electricity, the demand to develop effective methods for energy efficiency industries have grown.The electricity-intensive industries, such as plastic industry, the demand to reduce energy consumption has grown significantly over the past 10 years, which have led to the development of different methods to determine and locate energy-consuming parts in the industry. This also means being able to prioritize and organize activities in the industry.In this study the measurements of voltage, current, power and PF performance on injection molding machines (K-TEC 275 form Ferromatik Milacron in Germany) with a focus to locate, within a machine, various measures that could improve energy use in the plastics industry, in this case RostiGP in Gislaved. These measurements have been carried out with the help of a power quality clamp meter to carry out time logs of the machines for some time during normal word rate.
Analys av lageregenskaper utifrån mätningar i testrigg
Vertical hydropower units has a rotating mass of up to 1000 tons. For the generator and turbine to work well the rotating system is required to be centered in relation to the surrounding structure. This is achieved by means of radial bearings. The dynamic characteristics of these bearings have a strong impact on the overall rotational dynamics of the total system and thus influence the vibrations in the unit. At Vattenfall Research & Development in Älvkarleby ongoing research is taking place on how the bearing parameters should be represented in the rotor dynamic calculations.
Utveckling av en metod och en utrustning för mätning av bränslesprayers rörelsemängd
A new type of device for measuring thev m& ?rate of fuel sprays from a diesel fuel injector has been developed and the various steps in the development are described. The device works by deflecting all of the sprays from the injector at the same time by using a bell shaped deflector. A load cell consisting of a machined steel part with strain gauges mounted on it measures the resulting force. The shape of the curvature in the deflector bell shape has been evaluated by photographing the flow in a 2D?version of the curve shape.
MÄTNING AV LJUDIMMISSION FRÅN VINDKRAFT. VIDAREUTVECKLING AV METOD FÖR MÄTNING
The Swedish government have a goal that wind turbines shall produce 30 TWh by the year 2020, compared to about 3,5 TWh produced in Sweden during 2010. To minimize the disturbance that wind turbines create the Swedish Environmental Protection Agency has stated a guideline value that noise from wind turbines at nearby residents shouldn?t exceed 40 dBA, at 8 m/s wind speed. With advanced calculation models, like Nord 2000, the emitted sound from future wind turbines can be calculated at an early stage to optimize the power production without exceeding the 40 dBA. When the turbines have been built there is a need to verify that they really are within the guideline.
Åsktransienter och överspänningar : En spänningsfylld simulering av elkraftsystemet vid Forsmark 3
A power system will inevitably be subjected to transient overvoltages, most often produced by switching operations and lightning strikes. These transient overvoltages may harm sensitive equipment without sufficient protection, but it is not an easy task to predict what transients may occur or how they affect the system. A fault occurred in a low voltage system at Forsmark 2012 and overvoltages from lightning were concluded as the probable cause. The three aims with this thesis are to develop and test a model of the power system at Forsmark 3, analyse the transient behaviour of the system when subjected to lightning surges and identify critical parameters, and lastly to provide a tool for investigating the protection of the system. The modelling and simulations were performed in the freely available simulation program LT Spice.
Kartläggning av begränsande faktorer vid fellokalisering med pulsekometod på mellanspänningskablar
I samband med att mellanspänningsnätet kablifieras ökar också kraven vad gäller fellokalisering. För att hålla avbrottstiderna i nätet korta är effektiv felsökning erforderlig. Detta arbete syftar till att kartlägga och redogöra för begränsande faktorer som finns vid fellokalisering med fokus på pulsekometoden. Uppdraget utförs tillsammans med Vattenfall Eldistribution AB.Det har uppdagats problem gällande fellokalisering på mellanspänningskablar med pulsekometoden. Ett flertal faktorer bidrar till denna problematik.
Systematiskt arbete för att hantera osäkerheter vid mätning : vid Q-Med AB i Uppsala
This report is about helping Q-Med AB in Uppsala to start its implementation of uncertainty of measurements analyses in their manufacturing department. Prior to this, the company relied solely on personal experience or did not take this uncertainty into consideration at all during different kind of measurements, which means that some of the processes that the company previously believed were within specified acceptance limits, will actually fail when considering these sources of uncertainties.Q-Med AB needed some sort of instruction to help the company, in a systematic way, to investigate different types of disorders that are affecting all kinds of measurements. This instruction includes a short summary about measurements and uncertainty of measurements in general and a detailed procedure about how these uncertainties are going to be handled in their daily work.The goal was to be able to use this instruction to systematically locate, eliminate (when possible) and analyze all kinds of disorders when measuring. Q-Med is using a lot of different types of instruments when measuring different types of quantities, including temperature, mass, pressure and density. This instruction will hereafter be used for every instrument, regardless of quantity and type of instrument.The instruction is tested through 4 different kinds of measurements, for mass, temperature and humidity.