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6095 Uppsatser om High-performance concrete - Sida 17 av 407
Spillvärmeåtervinning
SAPA´s resource of waste heat is the basis for this thesis to investigate the possibility of energy assets in their cooling water and possible uses for it. The energy in the waste water is greater than the current need which has three uses which are (1) heating the factory, (2) converting liquid propane to propane gas and (3) local domestic heating. The average energy load that is available is 1, 7 MW and the average temperature in the cooling water is 41°C. The total energy load at dimensioning out side temperature is approximately 1,6 MW for the three current uses. The temperature is currently too low to be used directly in the existing systems so an upgrade is needed.
Axial- och gradientkrympning hos golv på mark enligt Eurokod 2 : Sprickbredders beroende av betongkvalité, tvångseffekter och armeringshalt
AbstractConcrete foundation slabs are usually exposed to unilateral drying during the curing process. The unilateral drying causes an axial shrinkage and a concave curvature of the construction. The curvature results from the fact that the upper part of the slab is drying and shrinking faster than the lower part. This is called gradient shrinkage.A problem occurs when the slab is considered fully restrained by adjoining structural parts. The deformations caused by axial contraction due to the constant part of the shrinkage and the curvature caused by gradient shrinkage of the slab are then prevented by the fact that the slab is fully restrained.
Prestationspåverkan av flerträdshantering i klena gallringar
The aim of this study is to investigate how multiple tree handling harvesters perform compared to earlier developed standards. The study shows that multiple tree handling harvesters are more efficient in thinnings stands with mean stock volumes less than 0,12 m3fub per stock. The increased efficiency is different for different mean stem classes. In stands with a mean stem volume of 0,04 m3fub per stock, the increase can be as high as 40 percent while it is about 10 percent in stands with a mean stem volume of 0,12 m3fub.
Comparisons have been done between stands that are felled with partly limbed stands and stands without partly limbed assortments. The difference in performance is clear and shows that the partly limbed assortments strengthen the multiple tree handling harvesters positive effects in low dimension thinnings.
Bedömning förr och nu : En studie i bedömning genom grundskolan
AbstractAimThe aim is that by using the curriculumcodes, analyze and compare four curriculums in physical education. The study begins in the elementary school introduction in 1962, and then makes three more strikes in 1980, 1994 and 2011.The questions that are addressed in this paper are,Which expression of competence code can be found in the different curricular?What are the expressions for performance code can be found in the different curricula?Is there any change regarding which code teachers use when they assess the students?Method As a basis, the four curricula Lgr 62 Lgr 80, Lpo 94 and Lgr 11 in physical education are used. These four curriculums are studied and compared for similarities and changes in the assessment uses comparative content analysis. A number of publications in the curriculum codes are used in the analysis of the curriculum.
En skola är en skola, är det EN skola?
Ett utvecklingsarbete med gymnasielever om faktorer som ligger utanför skoltid och som de anser inverkar på deras skolprestation. The purpose of this paper was to develop a material that highlights what causes there were outside school that pupils thought affected their performance in school. This was strictly done according to the statements that the pupils made. To fetch these statements the paper used essays, interviews and inquiries, all of whom were presented for the pupils. Initially we asked the pupils to write a short essay where we wanted them to describe circumstances in the classroom, in school and spare time that affects their performance in school.
Hantering av personuppgifter ? en arbetsmiljöfråga?
Unhealthiness is not just a damaged back or asbestos. The fact that mental ill-health seems to increase in our society is well known. Statistics from Arbetsmiljöverket proves a fourfold increase of work-related disorders since 1997. These are primarily caused by organizational and social factors, 60% are considered caused by stress and a heavy workload. Sick leave due work related fatigue and depressions are scarily common today.
Tryckhållfasthet för resurssnål betong : Utvärdering i tävling av högsta tryckhållfasthet för resurssnål betong
Betong är vårt vanligaste byggmaterial men cement står globalt sett för 5 % av CO2-emissionerna. Med detta som bakgrund så har CBI Betonginstitutet anordnat en tävling, där målet är att nå den högsta tryckhållfasthet i en resurssnål betong, med enbart 200 kg cement per m3. Syftet med denna rapport är att utvärdera tävlingen, vilket har utförts genom en omfattande litteraturstudie. En första analys av de olika betongrecepten medförde att olika grupperingar kunde urskiljas. Ur dessa fanns det tre stycken vars resultat var väldigt bra. ? Concrete Innovation Centre, som med ett lågt vct, stora mängder granulerad masugnsslagg (81 %) och lite silikastoft (5 %), uppnådde en tryckhållfasthet på 80 MPa vid 28 dygn och 95 MPa vid 56 dygn. ? CBI Stockholm, som genom användandet av ulltrafint filler och silikastoft (4,8 %), uppnådde en tryckhållfasthet på 84 MPa vid 28 dygn och 98 MPa vid 56 dygn. ? Thomas Concrete Group som genom att ersätta cementet med en medelmåttig mängd granulerad masugnsslagg (54 %), liten mängd flygaska (9 %), kalkfiller och silikastoft (5 %), uppnådde en tryckhållfasthet på 94 MPa vid 28 dygn och 98 MPa vid 56 dygn. Det finns således tre recept som vidare studier kan vara rättfärdigade på, de tre ovan nämnda. Det bör tilläggas att en imponerande tryckhållfasthet på nästan 100 MPa, kan uppnås i en betong med enbart 200 kg cement per m3. .
Upplevelse av arbetsglädje och känsla av sammanhang - en enkätstudie bland anställda på en högskola
Man spends most part of the day at work and is therefore influenced by it?s ambience. That?s why it?s important that the environment at work is health promoting and can function as a supportive environment. The purpose of this study was to describe job satisfaction among employees and to analyse a possible connection between job satisfaction and employees experiences of SOC.
Förbättring av U-värde i träkonstruktion för fönster med Aerogel
When constructing a building, a number of aspects must be harmonized in order for it to fulfill requirements ? a building must fulfill requirements such a load-bearing, conservation of energy and a good indoor environment by means of, among other things, moisture proofing .Moisture problems in buildings can affect health negatively. As we are increasingly staying in indoors, demands on a good indoor environment are higher.This work starts with examining moisture problems in slab-on-ground solutions, and then links the various scenarios to moisture problems in a concrete slab of a real building. The building with moisture problems is located in Årby by in Borlänge and moisture damage was found in the slab at an apartment adjoining wall.By reviewing literature written within the field of moisture problem, making hand calculations and modeling in the program Comsol Multiphysics, judgments are made to find explanations as to why the rise of moisture occurred in the building in Årby by.Generally, the following guidelines may be used to reduce the risk of moisture problems in slab-on-ground constructions:Drying of construction moisture before laying the floor material.Using draining layer beneath the slab, to prevent capillary suction.Using insulation under the slab, partly for comfort and to establish the temperature difference between the ground and the concrete slab.Avoid direct contact between the wood and concrete, due to degradation and fouling smells that normally occurs.If necessary, use additional vapor barrier.In addition to the above, there are various methods for moisture-proof and moisture-monitoring by design or by the method ByggaF suited for the entire construction process various events..
Development of concrete compressive strength: a study of Swedish bridges constructed during the 20th century
Tryckhållfasthetsutveckling hos broar. En studie av svenska broar byggda under 1900-talet.
Solcellsdrivning av distribuerade inbyggda system
The high level of energy consumption that the industrialised countries have reached and thepollution that this brings has long been a cause for analysis and debate, development and usageof so called renewable energy sources is therefore more important than ever. The energy in theelectromagnetic radiation from the sun is an interesting alternative. One way of harvesting thisenergy is by using solar cells, devices that generate DC current when exposed to electromagneticradiation.The goal of this master?s thesis was to design a solar powered power supply to Syntronic AB?sMidrange platform. The envisioned application is a stand-alone distributed embedded system,for example a node-based temperature monitoring system.
Vakuumbrytare i småskaliga vattenkraftstationer
This master thesis has been performed at Vattenfall Power Consultant in Gothenburg and Trollhättan for Vattenfall Vattenkraft. In this report vacuum circuit breaker in small-scale hydropower stations with the rated power 4 MVA and below has been studied. Models of the stations are modeled and analyzed in PSCAD/EMTDC to study the high voltage transients that are created after current chopping with vacuum circuit breaker. Vacuum circuit breaker may chop the current before it reaches zero value, which means that high voltage transients can be created. The equipment of the stations can be destroyed by high voltage transients.The purpose of this thesis is to examine the use of vacuum circuit breaker in small-scale hydropower stations and the risk for high voltage transients from current chopping.According to the results there is a risk of high voltage transients after current chopping with small synchronous generators in stations with the operating voltages 0.4 kV and 3.6 kV.
Generationsskräpsamling med explicit kontroll av hårdvarucache
This report evaluates whether an interpreted high-level garbage collected language has enough information about its memory behaviour to make better cache decisions than modern general CPU hardware.With a generational garbage collector, depending on promotion algorithm and generation size, around 90% of all objects never leave the first generation. This report is based on the hypothesis that, because of the low promotion rate, accesses to higher generations are sufficiently rare not to benefit from caching.To test this hypothesis, we built an operating system with a Scheme interpreter in kernel mode, where the interpreter controls the cache. Generic x86 PC hardware was used, since it allows fine-grained control of cache decisions.Measurements of execution time in this interpreter show that disabling the cache for generations higher than the first does not give any performance gain, but rather a performance loss of up to 50%.We conclude that this interpreter design is not an improvement, but cannot conclude that the hypothesis is false in general. We suggest building a better CPU simulator to gather more data from which to make better caching decisions, moving internal interpreter data structures into the garbage collected heap and modifying the hardware to allow control in the currently rigid dimension of where data is cached---for example separate control of instruction and data caches and separate data caches for different areas of memory..
Val av stommaterial : Vilket är det mest fördelaktiga stommaterialet vid uppförande av en hallbyggnad?
When constructing an industrial- or hall building, the most common framework materials thatis used are wood, steel or concrete. Due to an assignment from Byggnadstekniska Byrån ABhas a document been created that makes it possible to investigate how the final costs is af-fected by gapes in between elements and which used foundation. And this with steel as thematerial. The purpose with this essay is to investigate which is the most well fitted materialwhen constructing an industrial- or hall building wood, steel or concrete. Information aboutthe different materials has been collected by litterateurs and by different internet pages.
Ny brandstation i Viskafors
ABSTRACTThe discussions about energy use have increased year by year everywhere in the society, and so also in the healthcare sector. But what is actually energy use in a hospital facility, and what affects it?The typical way today to express the energy use is in kWh/m2. The problem with a key performance indicator that is expressed as energy use in relation to a specific area is that it does not take into account the activity in the building. Even though the activity to a very high extent affects the energy use.