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1615 Uppsatser om Two phase flow - Sida 54 av 108

A Swedish national forest programme ? participation and international agreements

Sweden is in the initial phase of forming a national forest programme (nfp). The establishment of an nfp has been evoked by international policy developments and a national debate questioning Swedish forestry and forest policy. National forest programmes are participatory processes for the development and implementation of forest-related policies and international commitments. Hence, the aim of this master thesis is to assess the stakeholders? acceptance of participation and integration of international issues within the Swedish national forest programme.

Påverkas röstkällans egenskaper av förändrad stående kroppshållning? En experimentell studie av otränade mansröster

The aim of this study was to investigate whether a direct shift inpostural alignment results in changes in voice source characteristics. Ninemales with untrained voices were recorded standing in ideal posturalalignment and in the deviant postures swayback and kyphosis characterizedby extended hips and a slump back respectively. The voice source wasderived from the audio signal by inverse filtering. The parameters pulseamplitude, maximal flow declination rate, level difference between the firstand second voice source partials, closed quotient and the normalizedamplitude quotient in relation to subglottal pressure were compared betweenideal postural alignment and swayback and kyphosis respectively. Resultsindicate an impact of changed postural alignment on the voice source.Swayback posture gave significantly less pulse amplitude and maximal flowdeclination rate and significantly higher subglottal pressures thus resulting ina less effective phonation.

Slithållfastheten för dentin och cement i förhållande till emalj in vivo hos häst

The female dog has a unique reproductive endocrinology, with high levels of progesterone throughout the 70-day long luteal phase. In this project, markers of glucose metabolism were studied and compared from the aspects of breed group and time in oestral cycle. The parameters studied were: glucose, insulin, progesterone, fructosamine and the newly introduced analysis of HbA1c. Hba1c was also further evaluated and discussed as a diagnostic tool in canine medicine.No differences in terms of glucose markers were found between a group of purebreed dogs of various breeds compared to a group of dogs with high risk of dioestrus diabetes, namely the Norwegian and Swedish elkhounds.No differences were found between the two sample occasions, anoestrus and dioestrus, concluding that there is no need for relating test results to the time of the oestrous cycle in middle-aged intact female dogs.There were statistically significant higher values of all glucose markers in diabetic dogs than in non-diabetic dogs. When it came to HbA1c, however, there was a larger overlap between the two groups, compared to fructosamine.

Resonans

This report describes how the system may be exposed to oscillations and how this can lead to resonance. Resonance is a phenomenon that occurs when a system is affected by external periodic oscillations with frequencies close to the system's natural frequencies. Structures subjected to resonance can risk great damage and destruction, why resonance is something that is important to take into account when designing structures. Alternative ways to counteract resonance is to supply damping in the system. Damping means that the resonance decreases instead of letting the amplitude increase.The report discusses some examples on constructions that have experienced the effect of resonance.

Skydd mot yterosion i slänter av finmorän

Slopes in fine till soils are exposed to surface erosion due to rainfall, snowmelt and upland water sources. Large areas of road slopes are therefore covered for surface erosion protection. Preventive methods like ditches and trenches are also being used. Silt tills are particularly troublesome since the water can bring the soil into suspension and cause mudslides. Different methods for erosion protection have been studied in this work, with the emphasis placed on rockfill covering. The need for and the dimensioning of this type of covering has been examined in literature and field studies.

Vattennivåreglering i Avesta Lillfors : På uppdrag av Fortum Generation AB

I denna rapport utreds olika metoder för att kunna reglera vattennivån i vattenkraftverket Avesta Lillfors i Dalarna. Två kraftverk ligger endast 900 m uppströms och detta gör att svarstiderna blir korta och regleringen blir lätt nervös. Att använda sig av vattennivåreglering i ett kraftverk för-enklar dess styrning då anpassning till inflödet sker automatiskt.En flödestabell har tagits fram genom mätningar i turbinen, med hjälp av Winter-Kennedy-metoden. Denna tabell används för att kunna fram-koppla regulatorn och därmed dämpa stora variationer i inflödet. Dessu-tom har en modell av älven skapats och testats med en återkopplad PID-regulator.

Implementering av en PSS i Trängslets kraftstation

The purpose of this master thesis is to implement and validate a Power System Stabilizer (PSS) to a generator at Trängslet hydropower station in Dalarna, Sweden. Problems with local rotor oscillations can occur at the hydropower station when power is transferred on a new power line (130 kV) from Northern to Southern part of Dalarna. To ensure good operation properties on this power line Fortum Generation AB and Fortum Distribution AB wants to activate a PSS on a generator.There have been investigations in which situations and what equipment that contributes to rotor oscillations. When this is known the PSS is tuned to damp these oscillations by choosing a good set of parameters. The most important parameters for good performance are to choose amount of gain and phase compensation.

MEMS baserad referensoscillator

The interest in tiny wireless applications raises the demand for an integrated reference oscillator with the same performance as the macroscopic quartz crystal reference oscillators. The main challenge of the thesis is to prove that it is possible to build a MEMS based oscillator that approaches the accuracy level of existing quartz crystal oscillators. The MEMS resonator samples which Philips provides are measured and an equivalent electrical model is designed for them. This model is used in the simulations of the Pierce oscillator and the transresistance amplifier oscillator that are evaluated in this thesis. Finally the Pierce oscillator is implemented in the A BCD2 process and manufactured at Philips Semiconductors in Nijmegen, The Netherlands.

Avbördningskapacitet för Traryd kraftverk: en modellstudie vid dimensionerande flöde

Sydkraft Vattenkraft AB owns and operates the Traryd hydropower plant, located in the river Lagan in the southern part of Sweden. The gravity dam is classed according to RIDAS guidelines (Hydropower Industry Dam Safety Guidelines) as a class 1B dam. This means that the dam must discharge a class 1-flow which has a return period of 10 000 years. The inflow into the dam has been calculated in an earlier report to 495 m3/s, with a waterline at an elevation of 126, 3 meters above sea level. The gravity dam has a discharge system with two rectangular weirs, which results in a smaller discharge than the necessary 495 m3/s.

Energieffektiviserande åtgärderpå Robertsfors VA-nät : En förstudie av vilka energieffektiviserande åtgärdersom kan göras på pumpstationer och reningsverk

The objective of this work was to introduce measures to reduce energy and water demand at Gävle Söder 17:10. To succeed, this energy audit has been made. The work is based on collected statistics from the property owner Norrporten, measurements, literature review and through consultation with experts in the field. Two models, one for each building, have been created in the simulation program BV2 to estimate the potential of energy measures based on the collected information. The models in BV2 have been verified against the statistics of the energy consumption.With the help of calculations and simulations, seven cost-effective measures have been identified.

Förbättrad Kravhantering med hjälp av Lösningsinriktad Pedagogik

Abstract The purpose of writing this thesis was to improve methods during requirements engineering phase. Usercentred system engineering has some problem areas, which are examined and verified to create a new guideline for developers. This guideline tends to make requirements engineering more effective and help developers create more concrete requirements. It is not uncommon that system development projects ends up with unsatisfied users or delay in deliveries. The reasons are different kinds of communication problems between users and developers during verification of requirements.

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.

"Don´t put lipstick on a pig"

Spelifiering har funnits genom historien, utan att det tidigare har definierats. Spår av användning av begreppet finns på Internet sedan 2004, men begreppet blev populärt först runt 2010. Spelifiering kan beskrivas som en process där det lånas komponenter och upplägg från spelvärlden som appliceras på verksamheter som traditionellt inte hör samman med spelande. I vår undersökning riktar vi in oss på kopplingen mellan spelifiering och lärande, alltså spelifierat lärande. Syftet med denna studie är att ur ett diskursanalytiskt perspektiv beskriva vad det är som kännetecknar spelifierat lärande.

Reglerbara skovlar på pumphjul

The thesis investigates if it is possible to replace several pumpimpellers with one controllable pumpimpeller, with a economical and a manufacturing analisys aspect. The studied pumpimpeller is mounted on a midrange wastewaterpump, N3127MT.In the thesis a contemplated manufacturing process is evaluated for a concept that are supposed to act as a controllable pumpimpeller. The pumpimpeller are studied in a manufacturing and flow matter and are presented in the thesis.The manufacturing cost is also estimated, and this has been compared to the storage cost and other costs that the existing pumpimpeller generates.The thesis also shows that the concept has minor losses in cutting quality aswell as the effiency comparing to the existing pumpimpeller.The concept also raises the manufacturing cost and this increasing cost makes the presented concept to expensive to carry through.An investigation of the costs that the existing pumpimpeller produces has also been done, and this shows that there is not that much expenses to earn regarding to for example the storage cost. The storage cost includes information from Flygt?s central storagecenter in Lindas, Sweden and Metz, France, and also an inventory about the pumpimpellers located at Flygt?s different distributors worldwide.The thesis shows that a controllable pumpimpeller will generally increase the cost for the pumpimpeller and the performance of the pumpimpeller will decrease..

Dokumentation av en experimentell biogasanläggning

This thesis is   focused on identifying and documenting all   electrical equipment, such as devices, power lines / cables, and connectors in the facility and also on presenting a brief   technical description and information of the systems around the reactors.   Furthermore there will be a brief description of LabVIEW - which is a   graphical programming language- and which devices / elements   are programmed. For further notification, I am not   responsible for the programming of the devices in LabVIEW   which I have only used as a tool in my work. The plant   for production of biogas consists of four reactors   of which the third reactor (Lakbädden)   is connected to another reactor (UASB)   where they cooperate with each other.   The reactors are used for producing   biogas in the form of methane gas.The reactors I and II are   connected to, various electrical devices as, flow meters, temperature   sensors, frequency converter and   more.

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