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394 Uppsatser om Maximum-likelihood - Sida 12 av 27

Lagring av kyla med horisontella markvärmeväxlare för kylning av koncepthus i Mellanöstern

Norconsult AB has developed a solarhousing concept, a house designed for the warm climate in the Middle East andwith large quantities of solar panels installed. The cooling system for the house was designed in an earlier report, the purpose of this thesis is to investigate the possibility of short and long term storage of thermal energy via an underground energy storage volume.Two different designs of the storage and three different filling materials have been integrated into a model to simulate different cases. The first design consisted of pipes installed in the ground, without insulation. The second design consisted of an insulated concrete box installed to prevent thermal energy from the surrounding soil to flow towards the lower temperature regions within the storage. The three different filling materials were dry saudi sand, water saturated saudi sand and the filling material used by the client for energy storage in Sweden.The results from the simulations show that neither of the designs, regardless of the filling material, managed to extract enough thermal energy from the house to the ground to uphold the demands of indoor climate.

Självförsörjande elgenerering : Kan Orust bli självförsörjande på förnybar el?

Orust Kretsloppsakademi is a nonprofit organisation, with a goal of annually generate the same amount of electrical energy that is consumed. Orust is an island on the west coast of Sweden, north of Gothenburg. The population of 15 000 reaches 40 000 during summer, due to the large amount of vacationer. The total electricity demand is 174 GWh a year with a maximum power need of 32 MW. This report presents an analysis for the plausibility of their plan and from a power system stability perspective, the effects on the electrical grid.The conclusion is that the restraints for development of power generation from wind, solar and wave generation, are the power systems capability to transfer power, primarily in the transformers of the grid.

En arbetsmiljöutredning för yrkeschaufförer hos Schenker Åkeri AB i Halmstad

The project has been done in cooperation with Schenker Åkeri AB in Sweden, Halmstad. Theproject is based on an inspection made by Arbetsmiljöverket, where they found minorshortcomings with distribution of goods for the employees. The project is an investigation ofthe drivers? working environment.Schenker Logistics is one of the world's leading providers of integrated logistics services.Schenker Åkeri AB is a subsidiary to Schenker Logistics and transports 2.4 million tons ofgoods yearly.The project started with a background study to evaluate drivers working environment. Wehave studied goods receptions, the working environment, strain injury and injury mechanisms.Methods used was observations, tests, questionnaire surveys and ergonomic andbiomechanical calculations.One result of the study is a working model, which gives recommendations for the maximumweight a driver should push and pull.

Jämförande av Genesis Single och kliniska test : Muskelstyrka hos individer med tidigare ACL-skada

Inom sjukgymnastiken används mätning av muskelstyrka för att utvärdera och planera rehabiliteringsperioder. Isokinetiska dynamometrar och one repetition maximum (1RM) är två vanliga metoder för att mäta muskelstyrka. Efter en skada på främre korsbandet (ACL) sker en muskelatrofi av bland annat mm. quadriceps och hamstringsmuskulaturen och det är därför viktigt att kunna utvärdera dessa muskler. Genesis Single är en ny tränings- och utvärderingsmaskin på vilken inga tidigare studier gjorts.

Sinnlig stimulans i vaken vila : en studie av växter i en restorativ trädgård

Den här studien berör några av de miljöpsykologiska grunderna i Alnarps Rehabiliteringsträdgårds uppbyggnad. Den ger förslag på hur karaktären rofylld kan förstärkas och hur säsongen kan förlängas i den restorativa delen av välkomstträdgården med växter som tilltalar flera av våra sinnen. Deltagarna som kommer till trädgården har i regel stressrelaterade åkommor såsom utmattningssyndrom och har varit sjukskrivna en längre tid. De är ofta mycket känsliga på grund av fysisk och psykisk utmattning. Studier visar att deltagarna har behov av en kravlös miljö där de kan få vara ostörda.

Lantbruk i framtiden : ett praktikfall

The economic prerequisite to many farmers in Sweden after the EU membership and the new agriculture policy has generated large demands on the farm management. Until year 2004 you got a grant based on what you had produced and not on consumer demand. In 2005 a new economic aid (Mid Term Revue) was introduced and the conditions has changed again. Due to this I have chosen to do a cost-benefit analysis on a case, to investigate if the present production is sustainable in the future. My conclusion is that the profitability is acceptable even if the farm has a high debt. But to make the production more profitable the products produced should be refined as much as possible at the farm, to get maximum economic return.

Mobilt övervakningssystem : System för internetkommunikation mellan sensorer, webbsida, server och databas

This thesis has been carried out in cooperation with a company which develops mobile sensor platforms. The sensors measure different types of data such as temperature, pressure etc.. They will communicate through the internet with a server that stores data in a database. This system will be controlled and monitored through a web page. The project's aim has been to develop this system and to implement a server, a database, a website and a client application that simulates sensor signals.

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.

Biologiska behandlingsmetoder för rening av rejektvatten från biogasproduktion

In this literature review the characteristics of two free-floating macrophytes, water hyacinth   (Eichhornia crassipes) and duckweed (Lemna sp.), and two microalgae, Chlorella and Scenedesmus, have been examined regarding their suitability as efficient nutrient removers in the treatment of wastewater with high levels of nutrients and suspended solids from a biogas plant in Loudden. The needs required for the plants to be able to grow in wastewater and the amounts of biomass they can produce have also been studied. The results show that Chlorella is capable of a very high uptake of nutrients in photobioreactors with high nutrient loadings. With an ammonia uptake maximum value at 10900mg/m2/d Chlorella outshines the other organisms in this study. The test organism that performed the closest to Chlorella in terms of nitrogen uptake was water hyacinth with an uptake about 1602mg/m2/d.

Styrketillväxt med hjälp av vibrationsplatta

Abstract 1.The purpose of this study was to investigate the effects whole body vibrations on maximal strength, power output and neuromuscular activity in m. pectoralis major during bench press.Participants consisted of 35 male and 9 female military high school students (m=23, 1 years). On the basis of initial maximal performances in bench press the participants was divided into two experiments groups and one control group. Intervention groups performed a specifically designed push up program on a vibrating plate respectively a step board during 12 weeks Initial load at 60 % of 1 RM showed an average of 46, 5 kg. All groups showed an average increase of 13 kg for each person after 12 weeks.

Tidssynkroniserade mätningar i vattenkraftstationer

Vattenfall and Svenska Kraftnät perform start-up tests, where hydropower generators are used to power up the electrical grid in case of a blackout. To monitor the electrical grid, Phasor Measurement Units (PMU) are used. Each PMU is individually equipped with a GPS-receiver to precisely timestamp the data relative to the official time UTC. During the test, it is also of interest to timestamp the measurement signals from individual hydropower generators to later compare with PMU-data, and thus study the power grids impact on the generator. The aim is to work out an appropriate method to make these measurements and to build a data acquisition system, capable of timestamp data relative to UTC, from a generator in one of Vattenfalls hydroelectric power stations. The problem is that the generator is located in an underground station which hampers the reception of GPS-signals and wiring should be avoided if possible. Time synchronization has been solved by using Vattenfalls network, which is synchronized by the network protocol NTP.

Utdragshållfasthet av inlimmade skruvar i limträ

In this thesis tests has been performed on the pull strength of screws glued into glulam beams.The experiment is based on the already approved method whereby the diameter of the drilled holes is the same as the screw outer diameter of 1 mm or bigger. The screws strength class shall not be less than 4.6 (EN ISO 898-1:1999, 1999).The difference in the experiments that were performed where that the drilled diameter were 1 mm smaller than the outer diameter of the screw so that the screw thread was worked into the wood.In the tests the gluing where made on M8 glulam beams. The screws where drilled at and angel of 90°tangental to the fiber direction with a diameter of 7 mm. The gluing of the screws where made in three different depths and where later exposed to pulling forces. The results showed both pulling breaks and screw breaks when they reached their maximum capacity.

Augmented Commerce Index : Värdeskapande lösningar inom e-handeln

Today there are many technical solutionsfor the e-commerce industry, incombination with a change in behavior ofthe end user. The consumer of todaydemands more availability andconvenience.This Master?s thesis has examined thecritical aspects of e-commercecompanies, as well as how they candevelop their e-commerce to create valuefor the end user. The aim has been toidentify the more and less importantfactors of the e-commerce business, andto investigate the extent to which thesefactors are used in the e-commerceindustry. To answer these questions, aninteractive, online questionnairecustomized for e-commerce companies wasdeveloped.

Acceptansgränsen för solceller i lågspänningsnät : Kan den ökas?

Microproduction, also called distributed generation, is something that has become more and more popular in the electric grid. Microproduction can however lead to unacceptable performance if several units are installed in the same low voltage network. It is therefore good to know a limit where the performance of the low voltage network becomes unacceptable based on given parameters. This limit is usually called hosting capacity.In this report the hosting capacity with respect to voltage and current have been studied in three low voltage networks which are located in Falu Elnäts concession area. This has been done by simulations in a GIS-program where critical times of the grid have been simulated.

Slitundersökning för jordbearbetning och sådd :

In this study we try to focus on the costs for wear parts on different type of soil tillage machines and at Väderstad Rapid drilling machine. We have studied some of the leading types of cultivators and disk harrows. Among the cultivators we have investigated Väderstad Cultus, Dalbo Dinkomax, Horsch Tiger and Terrano. At disk harrow we have looked at Amazone Catros and Väderstad Carrier. We have made more detailed study on costs for wear parts, working depth, driving speed and diesel consumption.

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