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569 Uppsatser om Temperature gradient - Sida 1 av 38

Termisk analys av kompakta jordvärmesystem - Sensitivitetsanalys och korrektions faktorer baserat på fältmätningar i referensanläggningar i Östergötland

Chapter 1 defines the aim of the project and gives a general orientation about ground heat extractors. In chapter 2 physical processes that could be expected to be involved in the heat transport around a ground heat exchanger are discussed. It is shown from a literature study what amount of moisture transport due to thermal gradients there could be expected in a ground heat exchanger. The conclusion is drawn that the moisture gradient (Sr) is of same magnitude as the driving Temperature gradient (°C). At the expected amount of increased moisture around the pipes the moisture transport could be considered to have a little effect on the brine temperature.

Variation in protein precipitation and phenolic content within and among species across an elevational gradient in subarctic Sweden

This project investigated how elevation and vegetation type influences variation in plant litter phenolic content and protein precipitation capacity among and within common plant species for two different vegetation types, heath and meadow, in a subarctic ecosystem in the Abisko region of northern Sweden. As nutrient availability generally decreases with increasing elevation as a result of decreasing temperature, I hypothesised that phenolic content would increase with elevation and be higher on the heath than the meadow. To test this, the total phenolic content and protein precipitation capacity was estimated in leaf litter from 13 species in both heath and meadow vegetation across an elevational gradient ranging from 500 to 1000 meters above sea level (m.a.s.l.) in the study region. The results showed that elevation and vegetation type both had a strong impact on both variables. Total phenolic concentrations decreased with elevation for the meadow, and were greater for the heath than the meadow.

Temperaturstyrning av aluminiumextruderingsprocess

In this final thesis a rough description of aluminium extrusion is made, the importance of temperature of both the raw material and the extruded profile for a good profile quality. The difficulty in controlling these temperatures are discussed and attempts to increase the control are described. The attempts are basically made by controlling the furnace that is heating the raw material. This is done in a manner that the raw material reaches its final temperature shortly before it is extruded. An IR-camera at the press can be used for profile temperature measurements.

Sänkta sjöars inverkan på ytvatten i Västerbottens kustland : Samband mellan sänkningsnivåer och vattenkemi i sjöar på sulfidrika sedimentjordar

Lake lowering in sulphide-rich areas is currently a major environmental impact for surface water. This study focuses on whether there is a relationship between a gradient of lake lowering and surface water impacts in areas of sulphide-rich sediments, in order to better understand their contribution of heavy metals and sulfuric acid. Also, is it a reasonable method to use the reduced lake area in order to quantify the gradient? The survey was conducted by collecting water samples from reference lakes and lowered lakes from south to north in coastal areas within the county of Västerbotten. Water samples were then analyzed for TOC, pH, conductivity, anions, base cations, alkalinity, acidity, sulfate, Al, Cd, Fe, Mn, Cu, Zn and Pb.

Inverkan av stora mängder halm som underlag i grisningsboxen på den nyfödda smågrisens temperaturreglering :

The aim of the present study was to evaluate the effects of large amounts of straw in the farrowing pen on thermal regulation of the newborn piglet in different weight classes. 20 sows were given 15 kg of straw in the farrowing pen 2 days prior to until 7 days after parturition. A control group of 18 sows had no straw in the pen. 6 litters from each treatment were observed. Measurements of piglet body temperature were made at 0h, 2h, 4h, 8h and 24h after parturition. At ?8h? the body temperature of the piglets in the Straw group were significantly higher (P=0,0149) than the piglets in the Control group.

Kroppstemperatur och vattenavdunstning via huden hos extremt underburna barn vid vård i kuvös och med kängurumetoden

Aim: To examine the reaction of extreme preterm infants with regarding to body temperature and transepidermal water loss during skin-to-skin care according to Kangaroo Mother Care (KMC) during the infant?s first week of life. Method: This was a descriptive quantitatively designed study, which was a pilot study within the framework of a larger project. Nine children, with a median gestational age of 24.91 weeks, were examined by measuring body temperature (axilla and skin temperature) as well as transepidermal water loss before, during and after KMC. Results: The study showed that skin temperature tended to rise during KMC, especially for those children who were nursed with KMC for more than 60 minutes.

Test och verifiering av en ny inkapslingsmetod för SiC BJT och MOSFET

The use of silicon carbide (SiC) as a base material in power electronics has manyadvantages, including high breakdown voltage and excellent temperature endurance.However, the packaging of such electronics presents major challenges and there is aneed for packaging that can operate in higher temperature. The purpose of this thesishas been to develop a test method and verify the functionality of SiC powertransistors prototypes with a new packaging technique developed by Swerea IVF AB.It includes setting up an electrical test-bed for power and high temperature cyclingand analysis of the results. Even though test confirmed functionality after thepackaging process, (at room temperature) the performance seemed to have been reduced. This could be a result of the measurement setup and the packaging process.In higher temperature the transistors failed to operate longer than a couple ofminutes which showed the weaknesses in the design and the challenges with this typeof packaging..

Skadliga nollflödespunkter i Fortum Värmes fjärrvärmenät i Stockholm : En analys av dess förekomst och effekter

When several production units provide a district heating network, water is pumped from different directions. When the flows from the plants finally meet in the network, the water can be completely still. These places are called zero flow zones. In district heating networks with several plants, which also have different supply temperatures, large and frequent temperature fluctuations can occur when the zero flow zones move. This may cause wear on the pipes, a phenomenon called low cycle fatigue.For this reason it is important to examine where and when zero flow zones that cause temperature changes occur.

Värmestyrning I Handske

This rapport is result of a project. The purpose of which was to design a circuit that is used in a heat glove. The heat glove is the technical aid which provides heat inside a glove.It is specially suited for old people who have problems with cold hands because of decreased blood circulation.There already was an old circuit in the glove that gives a constant current which develops heat from battery to glove through a circuit. The temperature is between 32 and 34 degrees.The problem with the existing circuit was to regulate the temperature. There is only on/off switch and there is no way to adjust desirable value of the temperature.In order to solve the problem the old circuit was investigated.

Healthier vegetables through temperature stress? : a review of Brassica oleracea

The objective of this report is to present a review of the studies which has been carried out up to days date concerning how temperature affects vegetables physiologically when it comes to their health inducing as well as quality reducing features. The essay therefore starts off with defining what is meant by the terms health promoting and quality reducing features. It then moves on to describe how different subspecies of Brassica oleracea, that is to say vegetables such as broccoli, cauliflower, Brussels sprouts and kale, is affected by temperature. B. oleracea was chosen because the species contains several commercially interesting subspecies and therefore provides a broad field even though only one species is assessed.

Temperature monitoring during transport of test samples

Quality is the main focus in management of all laboratories. Accurate results of the analyses are not only determined by the analytical procedure but also by preanalytical factors. In the total analytical process of clinical specimens, there are many possible preanalytical sources of error. Monetoring of temperature on test samples of the transport boxes is one way to reduce the mistakes in the preanalytical phase.In this study, four laboratories from primary health care were invited to participate. The temperature has been measured on test samples of the transport boxes being delivered to the laboratory.In three cases the temperature remained within the limits, but in the fourth case the temperature varied more than the allowed interval.

Potatislagring :

The aim with the thesis is to get deeper knowledge in one of the subjects botany, livestock technology or economy. I have chosen to get deeper knowledge in how to store potatoes. How are you going to act to keep the quality on the potato during the storage, with a minimum of weight lost? My aim with this thesis is to get a view over how the potato act in storage space. The storage environment is very important in the storage space.

Sänkt returtemperatur : Potentiell besparing i fjärrvärmesystem

Optimizing energy systems is, in Sweden, as in many other countries, of growing interest. District heating systems are no exception. In 2012, 285 out of 290 municipals in Sweden had district heating in use and the majority of these systems have a higher return temperature than that which is possible with an error-free substation of day current technology. To, when possible, lower the return temperature is a way of increasing the effectiveness of the district heating system.This study means to investigate, through simulations and calculations, how big of a reduction in production cost a lower temperature in the city of Ystad?s district heating system would correspond to.

Tid kontra pengar : Goal-gradient effekt vid valet mellan nettonuvärdesmetoden och återbetalningsregeln

Syftet med denna uppsats var att studera om det finns en målgradient vid investeringsbedömning som medför en preferens för alternativ med kort återbetalningstid och snabba belöningar. Vi valde att genomföra denna studie med hjälp av en kvantitativ ansats, då vi genomförde ett experiment med studenter vid Blekinge Tekniska Högskola. Detta motiverar vi med att utifrån vårt syfte och vår teoretiska referensram, ger det oss störst möjlighet att generera ett intressant och relevant resultat. Vårt resultat visar tydligt att beslutsfattare föredrar att använda återbetalningsregeln före nettonuvärdesmetoden i en beslutssituation, och därmed ett fokus på tidsaspekten och när en investering är återbetald. 81 % av våra respondenter valde tidsalternativet i minst ett av de två casen.

Kartläggning av material flödesflaskhals i ICA butik.

In the spring of 2014 Sweco Systems AB were commissioned to design a ventilation system for a newly built preschool in Linköping. Terms from the client was that it cost efficiency would cope with the energy demands that are placed on the building. The unit chosen was a cross-flow heat exchanger, and this work is to compare it with two other heat exchangers to see if a more energy and cost efficient could have been chosen. The heat exchangers that was chosen for the comparison was a rotating- and a counterflow heat exchanger. Simulations have been made to the different heat exchangers by the manufacturers.

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