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455 Uppsatser om Voltage stability - Sida 11 av 31
Lodgepole pine - stability after thinning
SCA has today almost 300 000 hectares of their forest land planted with lodgepole pine(Pinus contorta var. latifolia). Due to initial extensive planting in the 1970ies the area oflodgepole pine forests in the thinning age has grown rapidly from the end of the 1990ies.During the years 1996-2005 first commercial thinning of lodgepole pine at SCA took place.The goal of the hereby presented study was to investigate the growth and stability in thosefirstly-thinned lodgepole pine stands a few years after thinning. Furthermore, the objectivewas to investigate the relationship between stand stability and different stand parameters.Additionally, lodgepole pine stem quality was estimated.The study is mainly based on the data collected during an inventory project carried out atSCA in 2008. Altogether 91 lodgepole pine stands in northern Sweden were measured afterthe first thinning.
Hisskärna av skalväggar i höga byggnader : Ett alternativ till den platsgjutna kärnan
A common way to stabilize high rise buildings is to use an elevator core built of concrete. Today, we use to build these elevator cores of in-situ concrete. Precast concrete twin wall (double wall) is a semi-finished product that has become more common in recent years. This diploma work studies how the twin wall works out as structural elements in an elevator core. The work also shows some possible ways of designing twin walls and highlights some important parts of the design that will be vital to the stability of the building. The result shows that it is important to think through where the element joints should be placed.
DESIGN AV ALUTON 38? FRAKTBÅT FÖR KUSTNÄRA TRANSPORTER
This master thesis is about designing and dimensioning a boat for transport of caravan, car, trailer or ATV. Buoyancy and stability are important properties as the pontoonboat should also be able to serve as a workboat. Many of the vessels on the market today that is being used for similar purpose are stable enough, but their hull is often similar with barges and thus too slow. This work has been to construct a boat that has good stability but also has a hull that enables it to move faster, is more maneuverable and having a more attracting design than today?s barges.
Design och implementation av konfigurationsverktyg för funktionsblock
Abstract In high voltage substations there is an increasing demand for computerized equipment, and automation of operation and supervision. The future primary equipment will provide the possibility to collect more information and to provide better control for improved effectiveness. Since ABB has got a large customer target, each product must be custom made to fulfil the customers (often from different countries) demands. Later these products will be configured by engineers who may not be familiar with the tools used at ABB. This is a very expensive and time consuming.
How to build a rein tension meter
A large part of the interactions between horse and rider during horseback riding takes place through the reins and the bit and devices for measuring the tension on the reins, rein tension meters, has fairly recently been developed. To safeguard the welfare of the ridden horse riders need to be aware of the rein tension they apply and actively work to decrease it. Furthermore, there is a need to develop the study of rein tension through new techniques and refined analysis procedures. A good-quality rein tension meter should be small in size, sensitive, durable and as accurate for light rein tension as for strong forces. Rein tension meters used in research on horse and rider interaction commonly depend on strain gauge technique for generating rein tension data.
Förbättrad förbränningsstabilitet i EBK för turbofläktmotor RM12 genom förändrad motorreglering : Improved afterburner combustion stability for turbofan engine RM12 by modified engine control
The engine of JAS 39 Gripen, RM12, has recently been equipped with a new flameholder and a new engine inlet. This change has caused an increased noise level from the engine when the afterburner is in use. The noise level reaches its peak when the afterburner is partially used. The problem is thought to be unstable combustion in the regions around the flameholder. A solution to the problem has been proposed by Volvo Aero.
Elektrolytisk reduktion av zink vid reningsprocess
When cylinders for motor saws are manufactured there are high demands on the cylinders strength and wearing qualities. Aluminum is a material with low density and is used by Husqvarna AB for their motor saw cylinders. The aluminum is strengthening with nickel that is attached to the cylinders through electrolysis. When aluminum is in contact with oxygen a film of oxide is formed. To eliminate the oxide and to prevent formation of new oxide zinc is used.
Storage stability in a milk based UHT-beverage : effect of pH, carrageenan and storage time
The different characteristics of many food products, such as aroma and texture, changes during storage time and become undesirable. The reason is instabilities within the product which become prominent as the product ages. These changes in characteristics are quality losses caused by changes in the product?s intrinsic and extrinsic environment. The stability in UHT-milk and beverages similar to it have been studied in the past decades and a certain focus have been on age gelation which is a common
defect in these type of products.
Ethnicity and Politics of Exclusion in Nigeria : Employing Rawls'Theory of Justice in Plural Societies
With an estimated 250 ethnic groups, Nigeria, no doubt, has been grappling with the problem of pluralism of ethnic nationalities. It is not news in Nigeria that extreme ethnic consciousness of its citizens has led to the victimization of one ethnic group by another. This victimization has come in the form of exclusions in the distribution of both wealth and power in the country.Amidst all the exclusions, the unity of the country has been ironically regarded as sacrosanct, and should not be negotiated. It is often said that fate brought all the ethnic nationalities in order to form one great country. I subscribe to this belief that fate brought us together for the above purpose, especially now that several countries around the world are merging in one way or the other to form a formidable force to reckon with both politically and economically.
Kartläggning av nätförlusternas storlek inom Mälarenergis elnät
Energy losses are an essential part of a power grid company?s costs. From anenvironmental and economic perspective, it is important to reduce these costs. Toknow where efforts should be deployed, it is important to have good knowledge ofwhere in the network losses are situated. When creating network tariffs, there is alsonecessary to have a correct distribution such that the network customers that use acertain part of the network, only pays for the network losses in this area.
Utvärdering av en ny selektionsmetod för hingstsperma : med avseende på membranintegriteten och membranstabiliteten
Today, equine breeding is based on performance and conformation, resulting in a vast variation in fertility among different horses, with noticeable economic losses as a consequence. The horse breeding industry is therefore in need of methods that diagnose the spermatozoa concerning their quality and provide the best sperm for AI. The commonly used selection methods for sperm today are: centrifugation, where extender is added, the sample is centrifuged and then resuspended; swim-up self-migration; adherence separation; and density gradient centrifugation. However, none of these methods are in used routinely in practice before inseminating mares with fresh or cooled semen.
The aim of this study was to evaluate a new selection method, Single Layer Centrifugation (SLC), and its effect on sperm viability. The viability was analyzed with regard to membrane integrity and membrane stability of ejaculated spermatozoa.
EU:s grannskapspolitik i Medelhavsregionen : En säkerhetspolitisk analys av Medelhavssamarbetet
AbstractThe thesis investigates how the European Union promotes stability and security in the Mediterranean region. The aim is to analyse the European Union?s security ambitions with Euro-Mediterranean Partnership, the Barcelona Process. An analytical framework with five sectors (military, political, economic, environmental and societal), based on the Copenhagen School?s theories about security sectors and securitization, is used for the analysis.
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 mätdata från nätstationer
Fortum has in a pilot project installed metering equipment with wireless communication in secondary substations in Stockholm. So far, the collected data are used only in specific projects.This master thesis was carried out at Fortum Distribution AB in Stockholm during 2013. The purpose of this study is to simplify and enhance the use of data in for example network planning process, by giving suggestions on how data can be managed and giving examples of analyzes that collected data can be used for.The electricity meter which Fortum has installed is a EDMI-Mk10A which is set to measure max/average/min values with a one hour time resolution of the following parameters: voltage (per phase), current (per phase) andactive power and active and reactive energy.In order to analyze the collected data an analysis tool is required. During this thesis two customized tools in Microsoft Excel have been developed, one for sorting data and one for analyzing.One aim of the thesis is to show examples of what collected measurement data can be used for. This work shows an example of analysis of active power, power factor, voltage, occurrence of interrupts and the relationship between outdoor temperature and power.This master thesis has among others resulted in the following advice: Expand the number of secondary substations with measuring equipment.
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.