• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 147
  • 138
  • 50
  • 38
  • 8
  • 6
  • 5
  • 5
  • 4
  • 4
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 480
  • 121
  • 41
  • 39
  • 38
  • 35
  • 34
  • 30
  • 29
  • 28
  • 26
  • 25
  • 24
  • 23
  • 23
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
101

Rock cavern as thermal energy storage

Berglund, Simon January 2020 (has links)
In the fall of 2019, a comprehensive idea study was conducted on heat storage in two rock caverns located at Näsudden in Skelleftehamn and was part of the project course "Energiteknik, huvudkurs" at Luleå University of Technology. This idea study investigated the conditions of using waste heat from Boliden AB:s copper smeltery (Rönnskär) and storing this waste heat in two rock caverns and use them as seasonal thermal storage tanks, with the purpose of using the heat in the nearby district heating network, thus replacing some of the oil burned at Rönnskär. To investigate this, the authors of the idea study looked at two different storage cycles of seasonal storage and modeled this in ANSYS Fluent to simulate the heat storage and the heat losses. The results from this idea study showed promising results for using these caverns as heat storage and this work is therefore a continuation of the idea study. Since the study provided a good understanding of the conditions for seasonal storage, some questions arose about how the rock caverns will behave during an intermittent operation, which is the planned mode of operating the caverns in case of deployment. In this thesis, intermittent operation of these caverns are explored and how this effects the temperature in the caverns and its surrondings, the charge/discharge speed, how insulated walls affect the operation and how much oil is replaced. At the beginning of this project a review of the idea study and similar projects was done to gain deeper knowledge about the subject, but also to get a wider grasp on the different problems that could arise during the thesis. Relevant data for the caverns was collected and acquired to get a deeper understanding of its geometry, layout and what kind of modifications are really possible. Further data from the district heating networks of Boliden AB and Skellefteå Kraft was acquired. The available waste heat from Rönnskär was examined and used to calculate the chargeable energy by hour for the caverns, with the limits of Skelleftehamn district heating network in mind. By examining the different steam boiler patterns, the discharge pattern could be calculated. Using CFD, the unknown global heat transfer coefficient between the cavern water and the cavern wall can be determined. This data was then used with a set of differential equations to model the behavior of the caverns in Simulink. This allowed to determine the behavior for the caverns during normal operation, such as how the heat losses evolve, how the temperatures fluctuate, how much heat the caverns can be charged with and how much they can discharge. The results from the simulations showed that the caverns discharge a higher amount of energy when operating intermittently than when operating seasonally. Depending on how the caverns are utilized, different amounts of discharged energy are obtained. This range from 2224,7MWh to 7846,1MWh for the different discharging patterns. The usage also affects the efficiency of the cavern giving the efficiency a range between 19% to 53,9%. The heat losses range from around 20kW to 1000kW, depending on operation. Insulating the cavern walls reduces on average the heat losses by a factor of 5. Operating the caverns intermittently would on average remove a total of 29 ktonne CO2 and 88,74 tonne NOx for its expected lifespan of 30 years. Economically, the rock caverns have good economic potential as they would save about 80 million SEK during their lifetime just from buying less oil. / Hösten 2019 genomfördes en omfattande idéstudie om värmelagring i två bergrum vid Näsudden i Skelleftehamn och var en del av projektkursen "\textit {Energiteknik, huvudkurs}" vid Luleå tekniska universitet. Denna idéstudie undersökte villkoren för att använda spillvärme från Boliden AB:s kopparsmältverk (Rönnskär) och lagra denna värme i bergrummen och använda dem som säsongslagrade ackumulatortankar. Syftet med detta var att använda värmen i det närliggande fjärrvärmenätverket och därmed ersätta en del av den förbrända oljan hos Rönnskär. Författarna utforskade detta genom att undersöka två olika lagringscykler för säsongslagring och modellerade detta i ANSYS Fluent för att simulera värmelagring och värmeförluster. Resultaten från idéstudien visade lovande resultat för säsongsbaserad värmelagring i dessa bergrum och detta arbete är därför en fortsättning av idéstudien. Eftersom studien gav en god förståelse för förhållandena för säsongslagring, uppstod några frågor om hur bergrummen kommer att bete sig under en intermittent drift, vilket är den planerade driften av bergrummen vid en framtida användning. I detta projekt undersöks intermittent drift av dessa bergrum och hur detta påverkar temperaturen i bergrummen och dess omgivning, laddnings- / urladdningshastigheten, hur isolerade väggar påverkar driften och hur oljeförbrukningen reduceras. I början av detta projekt gjordes en genomgång av idéstudien och liknande projekt för att få djupare kunskap om ämnet, men också för att få ett bredare grepp om de olika problem som kan uppstå under arbetets gång. Relevant data för bergrummen samlades in och anskaffades för att få en djupare förståelse för dess geometri, layout och vilken typ av ändringar som verkligen är möjliga. Ytterligare data från fjärrvärmenätverket för Boliden AB och Skellefteå Kraft förvärvades. Den tillgängliga spillvärme från Rönnskär undersöktes och användes för att beräkna den urladdningsbara energin per timme för bergrummen, med begränsningarna i Skelleftehamns fjärrvärmenät i åtanke. Genom att undersöka de olika ångpannmönstren kan urladdningsmönstret beräknas. Med hjälp av CFD kan den okända globala värmeöverföringskoefficienten mellan bergrumsvattnet och bergväggen bestämmas. Denna data användes sedan med en uppsättning differentialekvationer för att modellera driften av bergrummen i Simulink. Detta gjorde det möjligt att bestämma beteendet för bergrummen under normal drift, till exempel hur värmeförlusterna utvecklas, hur temperaturen fluktuerar, hur mycket värme bergrummen kan laddas med och hur mycket de kan ladda ur. Resultaten från simuleringarna visade att bergrummen kan ladda ur en större mängd energi än vid en säsongsbetonad drift. Beroende på hur grottorna utnyttjas erhålls olika mängder urladdad energi. Detta sträcker sig från 2224,7MWh till 7846,1MWh för de olika urladdningsmönstren. Användningen påverkar också grottans effektivitet vilket ger en effektivitet mellan 19% och 53,9%. Värmeförlusterna sträcker sig från cirka 1000 kW till 20kw, beroende på drift. Isolering av bergväggarna minskar i genomsnitt värmeförlusten med en faktor 5. Att använda grottorna intermittent skulle i genomsnitt ersätta totalt 29 kton CO2 och 88,74 ton NOx för den förväntade livslängden på 30 år. Bergrummen har även god ekonomisk potential eftersom de skulle spara cirka 80 miljoner SEK under sin livstid bara från minskade oljekostnader.
102

Patienters upplevelser av långvarig behandling med urinkateter / Patients’ experiences of a long-term catheter-treatment

Boquist, Emelie, Söderberg, Sofie January 2022 (has links)
Bakgrund: Det finns tre olika former av behandling med urinkateter vilka alla har olika egenskaper och påverkar användaren i olika utsträckning. Urinvägsinfektion är en vanlig komplikation i samband med kateteranvändning och den personliga upplevelsen av behandlingen skiljer sig beroende på vilken typ av urinkateter som används. En ökad förståelse för patienters upplevelser av långvarig behandling med urinkateter kan hjälpa sjuksköterskor att individanpassa information och omvårdnad avseende kateterbehandlingen. Syfte: Att beskriva patienters upplevelser av långvarig kateterbehandling i det dagliga livet. Metod: Denna studie har genomförts som en litteraturöversikt där 11 vetenskapliga artiklar utgör grunden för resultatet. Sökningarna har genomförts i databaserna CINAHL och PubMed. Resultat: I litteraturöversikten framkom ett antal områden vilka påverkade livet för kateteranvändare. Huvudkategorierna som identifierades var: Betydelsen av informationoch kunskap och Påverkan på individen. Vidare fann vi fem underkategorier: Handhavande, komplikationer, sexualitet, kroppsuppfattning och självbild, självständighet och dagliga aktiviteter. Slutsats: Kateteranvändande patienter önskar tydligare information kring kateteranvändande. Ökad kunskap och informationsnivå sågs stärka patienternas självkänsla och möjligheten att leva ett mer självständigt liv. För att säkerställa att patienternas frågor och behov tillgodoses krävs att sjuksköterskorna känner sig trygga och kompetenta i dessa avseenden. / Background: There are three different forms of treatment with urinary catheters, all of which have different characteristics and affect the user to different extents. Urinary tract infection is a common complication associated with catheter use, while the personal experience of thetreatment differs depending on the type of urinary catheter used. An increased understanding of patients’ experiences of long-term treatment with urinary catheters can help nurses to customize information and nursing regarding catheter treatment. Aim: To describe patients’ experience of long-term catheter treatment in daily life. Method: This study has been conducted as a literature review where 11 scientific articles form the basis for the results. The searches were performed in the databases CINAHL and PubMed. Results: The literature review revealed several areas that affected the lives of catheter users. The summary main categories that were identified were: The importance of information and knowledge and Impact on the individual. Furthermore, we found in these main categories six subcategories: Care, complications, sexuality, body image and self-image, independence, and daily activities. Conclusions: Catheter-using patients wants more information regarding catheter use. Increased knowledge was seen to strengthen patients’ self-esteem and the possibility to live a more independent life. To ensure that patients’ questions and needs are met, nurses must feel safe and competent in these regards.
103

Applying Memoization as an Approximate Computing Method for Transiently Powered Systems / Tillämpa Memoization i en Ungefärlig Beräkningsmetod för Transientdrivna System

Perju, Dragos-Stefan January 2019 (has links)
Internet of Things (IoT) is becoming a more and more prevailing technology, as it not only makes the routine of our life easier, but it also helps industry and enteprise become more efficient. The high potential of IoT can also help support our own population on Earth, through precision agriculture, smart transportation, smart city and so on. It is therefore important that IoT is made scalable in a sustainable manner, in order to secure our own future as well.The current work is concerning transiently powered systems (TPS), which are embedded systems that use energy harvesting as their only power source. In their basic form, TPS suffer frequent reboots due to unreliable availability of energy from the environment. Initially, the throughput of such systems are therefore lower than their battery-enabled counterparts. To improve this, TPS involve checkpointing of RAM and processor state to non-volatile memory, as to keep computation progress saved throughout power loss intervals.The aim of this project is to lower the number of checkpoints necessary during an application run on a TPS in the generic case, by using approximate computing. The energy need of TPS is lowered using approximations, meaning more results are coming through when the system is working between power loss periods. For this study, the memoization technique is implemented in the form of a hash table. The Kalman filter is taken as the testing application of choice, to run on the Microchip SAM-L11 embedded platform.The memoization technique manages to yield an improvement for the Kalman application considered, versus the initial baseline version of the program. A user is allowed to ”balance” between more energy savings but more inaccurate results or the opposite, by adjusting a ”quality knob” variable epsilon ϵ.For example, for an epsilon ϵ = 0.7, the improvement is of 32% fewer checkpoints needed than for the baseline version, with the output deviating by 42% on average and 71% at its maximum point.The proof of concept has been made, being that approximate computing can indeed improve the throughput of TPS and make them more feasiable. It is pointed out however that only one single application type was tested, with a certain input trace. The hash table method implemented can behave differently depending on what application and/or data it is working with. It is therefore suggested that a pre-analysis of the specific dataset and application can be done at design time, in order to check feasiability of applying approximations for the certain case considered. / Internet of Things (IoT) håller på att bli en mer och mer utbredd teknik, eftersom det inte bara underlättar rutiner i vårt liv, utan det hjälper också industrin och företag att bli effektivare. Den höga potentialen med IoT kan också hjälpa till att ge stöd åt vår egen befolkning på jorden, genom precisionslantbruk, smart transport, smarta städer och mer. Det är därför viktigt att IoT görs skalbart på ett hållbart sätt för att säkra vår egen framtid.Det nuvarande arbetet handlar om transientdrivna system (TPS), vilket är inbäddade system som använder energiskörning som sin enda kraftkälla. I sin grundform har TPS ofta återställningar på grund av opålitlig tillgång till energi från miljön. Ursprungligen är därför sådana systems genomströmning lägre än deras batteriaktiverade motsvarigheter. För att förbättra detta använder TPS kontrollpunkter i RAM och processortillstånd till icke-flyktigt minne, för att hålla beräkningsförloppet sparat under strömförlustintervaller.Syftet med detta projekt är att sänka antalet kontrollpunkter som krävs under en applikationskörning på en TPS i ett generiskt fall, genom att använda ungefärlig datorberäkning. Energibehovet för TPS sänks med ungefärliga belopp, vilket innebär att fler resultat kommer när systemet arbetar mellan strömförlustperioder. För denna studie implementeras memoiseringstekniken i form av en hashtabell. Kalman-filtret tas som testapplikation för att köra på Microchip SAM-L11 inbäddad plattform.Memoization-tekniken lyckas ge en förbättring för Kalman-applikationen som beaktades, jämfört med den ursprungliga baslinjeversionen av programmet. En användare får ”balansera” mellan mer energibesparingar men mer felaktiga resultat eller motsatsen genom att justera en ”kvalitetsrat”-variabel epsilon ϵ. Till exempel, för en epsilon ϵ = 0.7, är förbättringen 32% färre kontrollpunkter som behövs än för baslinjeversionen, med en utdata avvikelse med 42% i genomsnitt och 71% vid sin högsta punkt.Beviset på konceptet har gjorts, att ungefärlig databeräkning verkligen kan förbättra genomströmning av TPS och göra dem mer genomförbara. Det påpekas dock att endast en enda applikationstyp testades, med ett visst inmatningsspår. Den implementerade hashtabellmetoden kan bete sig annorlunda beroende på vilken applikation och/eller data den arbetar med. Det föreslås därför att en föranalys av det specifika datasättet och applikationen kan göras vid designtidpunkten för att kontrollera genomförbarheten av att tillämpa ungefärliga belopp för det aktuella fallet.
104

Open-Circuit-Voltage hysteresis measurement and modelling of LiFePO4 Batteries : Master Thesis Report - 2023

Larrat, Guillaume January 2023 (has links)
In a context of an expected increasing use of Lithium-ion batteries in the transportation sector, Volvo AB is developing its own solutions for large electric vehicles. It is then beneficial to reduce the costs, the energy demand and the raw materials demand by improving the battery systems’ performances. For that purpose, understanding the physical phenomena which come into play in lithium ion cells is necessary. This project’s motivation has been to deepen the existing knowledge on one or a group of these phenomena which include those at the origin of the Open Circuit Voltage (OCV) hysteresis. It is characterized by the difference in charging and discharging voltage when the cell is at a resting state. These voltage differences might result in heat losses in the cells. In this thesis, the behaviour of the Open Circuit Voltage (OCV) under different operating conditions is studied, and a Preisach empirical hysteresis model is developed. The core part of the work consisted in experimental measurements of the Open-Circuit-Voltage of 10 Ah prismatic LiFePO4 (Lithium Iron Phosphate) cells. These measurements were completed using the Galvanostatic Intermittent Titration Technique (GITT) that consists of alternative current pulse and relaxation phases. The tests were performed using relaxation times ranging from 1 hour to 48 hours with the cells being under various cycles (series of charge and discharge). The impacts of the temperature, various current rates from 0.1C to 1C (1 A to 10 A) on the OCV and the voltage relaxation were evaluated. The amplitude of the OCV hysteresis that does not vanish after full relaxation, which is defined by the difference between the OCV charge and the OCV after discharge, was found to vary between 5 mV and 20-25 mV depending on the State-of-Charge of the cells. Two peaks are identified around 20-30% and 65-70% State-of-Charge. The measured OCV hysteresis with 24 hours relaxation is about half of the measured OCV hysteresis with 2-5 hours relaxation. The experiments also measured an apparent smaller OCV hysteresis when the magnitude of the current increases; this trend is to be verified after full relaxation. The temperature has an impact on the OCV which is averaging around ±0.2 mV/K. The analysis of the voltage relaxation behaviour described that at low temperatures and low C-Rates, the cells get closer to equilibrium voltage at a slower pace. In addition, a higher test time, characterized by longer relaxation times after each step and/or a larger number of steps within the same State of Charge (SOC) range, tends to increase the time required for the cell to reach an equilibrium. After completing the OCV measurements, a Preisach hysteresis model is developed based on the experimental results. The model predicts the OCV variations of an Lithium ferrophosphate (LFP) cell at ambient temperature when going through various charge and discharge cycles. Its estimated Root Mean Square Error (RMSE) is 3 mV, but the accuracy of the model could be partially confounded with measurement uncertainty. The main outcomes are a more accurate description of the voltage relaxation behaviour and a new estimation of the amplitude of the OCV hysteresis in LFP cells. / I en värld där det finns en förväntad ökning av användandet av litiumjonbatterier inom transportsektorn, utvecklar AB Volvo sina egna lösningar för stora elfordon som lastbilar. För att reducera kostnaderna, energibehovet och efterfrågan på råvaror, är det nödvändigt att förstå fysiska fenomen inom litiumjoncellerna eftersom det kan hjälpa till att förbättra systemens prestanda. Examensarbetets motivation är att fördjupa kunskapen om fenomenen vid uppkomsten av öppen kretsspänningshysteres inom litiumjärnfosfatceller. Denna hysteres definieras av skillnaden mellan öppen kretsspänning (Open-Circuit-Voltage eller OCV) under laddning och OCV under urladdning. Det orsakar över- och underspänning som ökar värmeförlusterna i litiumjoncellerna. Detta projekt studerar beteendet av både spänningsrelaxation och OCV för ett valt intervall av parametrar. Sedan utvecklas en Preisach empirisk modell. Huvuddelen av arbetet bestod i den experimentella mätningen av OCV av 10 Ah prismatiska LiFePO4 celler (Litiumjärnfosfatceller). Dessa experiment genomfördes medelst en mätprocedur som kallas Galvanostatic Intermittent Titration Technique eller Galvanostatisk intermittent titreringsteknik (GITT). Testerna innehåller växelvis strömpuls- och relaxationsfaser. Spänningsrelaxationsfaserna varade mellan 1 och 48 timmar under olika laddnings- och urladdningscykler. Inverkan av båda temperaturen och strömstyrkan (mellan 0.1C och 1C) på OCV utvärderades. Amplituden för OCV hysteresen som kvarstår efter full relaxation beräknades ligga mellan 5 mV och 20-25 mV beroende på cellersladdningstillstånd. Två hysterestoppar identifierades: en runt 70% och en andra mellan 20% och 30% laddningstillstånd. Hysteresen som mäts med 24 timmar av relaxation är runt hälften av hysteresen som mäts med två till fem timmar av relaxation. Med större strömstyrka är den uppmätta hysteresen lite lägre. Ytterligare tester bör göras för att verifiera att hysteresen fortfarande är lägre efter full relaxation. Temperaturen har en begränsad effekt på den totala hysteresen, men entropikoefficientensvärdet är i genomsnitt runt ± 0.2 mV/K. Analysen av relaxations beteende beskriver att en högre temperatur och strömstyrka ökar hastigheten med vilken jämviktspotentialen nås efter strömpulsen. Dessutom orsakaren ökning av den totala testlängden en långsammare relaxering. En längre testtid karaktäriseras av en längre relaxationstid efter varje strömpuls och/eller flera steg för laddningstillstånd. Efter OCV-mätningarna, byggdes en Preisach hysteresmodel med hjälp av de experimentella resultaten. OCV-variationer under olika laddnings och urladdnings cykler modellerades vid rumstemperatur med ett uppskattat minsta kvadratfel på cirka 3 mV. Modellen testades inte med ett begränsat antal cykler så den exakta noggrannheten behöver ytterligare verifieras för att få ner mätosäkerheten. Det huvudsakliga bidraget från detta examensarbete är uppskattning av amplituden för den hysteresen och beskrivningen av spänningsrelaxering efter olika strömpulser, såväl i längd som i amplitud.
105

Patienters upplevelse av ren intermittent kateterisering : En intervjustudie

Hedman-Lindqvist, Nilla January 2016 (has links)
Bakgrund: Ren intermittent katetrisering (RIK) är en åtgärd som utförs dagligen på ett flertal patienter inom sjukvården, där sjukvårdspersonal tränger innanför patientens integritetssfär. Patienter har olika personliga gränser för när den personliga integriteten hotas och deras upplevelse vid RIK postoperativt, är sparsamt belyst i tidigare forskning.  Syfte: Att beskriva patienters upplevelse av ren intermittent kateterisering postoperativt. Metod: Datainsamlingen genomfördes med semistrukturerade intervjuer där tretton patienter som kateteriserats postoperativt deltog. Data analyserades med kvalitativ innehållsanalys. Resultat: Resultatet visade att patienterna upplevde vårdpersonalen som kompetenta och de förlitade sig på att vårdpersonalen visste vad som var bäst för patienterna som också kände sig omhändertagna. Det upplevdes vara viktigt att bevara den personliga integriteten och de påtalade vikten av tillräckligt insynsskydd vid kateteriseringen vilket inte alltid varit tillfyllest. Patienterna uttryckte också rädsla dels för smärta i samband med kateteriseringen och dels för att de trodde att det var något fel eftersom de inte kunde urinera. Några beskrev det som en lättnad att få hjälp att tömma blåsan, medan andra kände sig utlämnade och upplevde det som att de inte hade något val. Majoriteten av patienterna hade inte fått/kom inte ihåg att de fått adekvat information om att kateterisering kunde komma att behövas postoperativt och de påtalade vikten av att detta gavs innan operationen. Slutsats: Vårdpersonalens bemötande av patienter som behöver genomgå RIK är av största vikt för patientens upplevelse av vårdsituationen. Vikten av att information ges, som är adekvat och lättförståelig, poängteras. Det är en fördel om patienten görs delaktig i sin vård och att hänsyn även tas till speciella önskemål, som t.ex. kön på den som utför kateteriseringen. / Background: Clean intermittent catheterization is an action that is performed daily on several patients in health care, where health care staff penetrates inside the patients privacy sphere. Patients’ have different personal limits when privacy is threatened and research with focus on the patients experience of clean intermittent catheterization postoperatively is limited. Aim: To describe patients’ experience of clean intermittent catheterization postoperatively. Method: Data collection was conducted by using semi-structured interviews with thirteen patients that had been catheterized postoperatively. Data were analysed using qualitative content analysis. Result: The result showed that patients’ experienced health care staff as competent and they relied on that the medical staff knew what was best for the patients who also felt cared for. It felt to be important to preserve privacy and they stressed the importance of sufficient transparency protection during catheterization which had not always been satisfactory. The patients’ expressed fear partly for pain associated with catheterization and partly because they thought there was something wrong since they were unable to urinate. Some described it as a relief to get help emptying the bladder, while others felt vulnerable and felt that they had no choice. The majority of patients’ had not got or could not remember if they had received adequate information that catheterization could be needed postoperatively and they emphasized importance of that this information was given before surgery. Conclusion: Health care staff treatment of patient’s requiring clean intermittent catheterisation is crucial for the patient's experience of the care situation. The importance that the information given is adequate and understandable was emphasized. It is an advantage if the patient is involved in care and that consideration to special requests, such as that the gender of the person performing catheterisation is considered.
106

"Du dör inte av att vara hungrig en stund" : Människors erfarenheter kring intermittent fasta och drivkrafterna bakom denna kosthållning / "You don’t die from being hungry for a while" : People’s experiences of intermittent fasting and the motives behind this diet

Olesen, Pauline, West, Camilla January 2013 (has links)
Bakgrund Intermittent fasta är ett aktuellt ämne som fått stort genomslag i Sverige. Forskningen har konstaterat att intermittent fasta kan påverka kroppsvikten och den mentala hälsan. Det har även observerats ett samband mellan intermittent fasta och förlängt liv. Syfte Syftet med studien var att utforska vilka upplevelser och erfarenheter människor har som går eller har gått på en intermittent fasta, samt ta reda på vilka motiv och drivkrafter som influerar människor till att utöva denna kosthållning. Metod Åtta kvalitativa intervjuer med semistrukturerad frågeguide genomfördes. Intervjuerna spelades in och transkriberades ordagrant. Datainsamlingen analyserades med kvalitativ innehållsanalys. Resultat Deltagarna ansåg att fasta bara handlade om att ta en paus från att äta. Drivkrafterna som låg bakom utövandet av intermittent fasta var framför allt viktnedgång, förändrad kroppssammansättning samt förbättrad mental och fysisk prestation. Det fanns en allmän uppfattning om att hungern var påtaglig under fastan men att den var hanterbar. Många var överens om att det kunde vara svårt att fasta vid sociala sammanhang men att det var viktigt att vara flexibel med fastan och inte bli fundamental. Slutsats Viktnedgång var den största drivkraften till varför deltagarna utövade intermittent fasta. Dieten var något deltagarna kunde vara flexibla med, dels för att inte låta dieten styra ens liv men också för att inte avvika från de sociala normerna. Hungern sågs som en liten uppoffring för att få en kropp som stämmer överens med samhällets kroppsideal. / Background Intermittent fasting is a current topic that has had great impact in Sweden. Research has found that intermittent fasting can affect body weight and mental health. It has also been observed a correlation between intermittent fasting and a longer life. Objective The aim of the study was to explore the experiences of people who follow or has followed an intermittent fasting, as well the motives and driving forces that influence people to practice this diet.M ethod Eight qualitative interviews with a semi-structured interview guide were conducted. The interviews were recorded and transcribed word for word. The data collection was analyzed using a qualitative content analysis. Results Participants believed that fasting just is about taking a break from eating. The motives behind the practice of intermittent fasting were particularly weight loss, changes in body composition and improved mental and physical performance. There was a general perception that the hunger could be apparent during the period of fasting but it was manageable. Several agreed that it could be difficult to fast in social contexts but it was important to be flexible with the fast and not to be fundamental. Conclusion Weight loss was the major motivator as to why participants began practicing intermittent fasting. The diet was something participants could be flexible with, partly because they did not want to let the diet control their life, but also because they did not want to deviate from social norms. The hunger was considered as a small sacrifice to get a body that lived up to society's ideals.
107

Fitness assessment and recovery strategies for soccer

Erith, Samuel January 2007 (has links)
In recent years our understanding of the physical demands of soccer has improved. We know that the intensity at which the game is played has increased and that the fixture schedules for professional teams can often be very congested. These factors are likely to have increased the importance placed on the physical condition of players. Therefore, the process of monitoring the fitness levels of players is likely to be an important task within clubs. Any fitness assessments that are employed need to be sensitive enough to detect changes that may result from different training stimuli. A further critical consideration for clubs is what are the best practices to implement in order to maximise recover between matches? The two areas that are central to successful recovery of performance are the restoration of muscle and liver glycogen stores and the rapid reduction of muscle soreness. We have a good understanding of the importance of carbohydrate feeding in the immediate hours following the completion of exercise, furthermore that high levels of carbohydrate consumed during short recovery periods can improve subsequent endurance running capacity in both continuous and intermittent exercise. However, there is dearth of literature investigating the effects that different types (glycemic index) of carbohydrates have on subsequent performance of high intensity intermittent exercise. Furthermore, we know that the movement patterns experienced in soccer commonly induce symptoms of muscle damage. Despite this there is little research based information on modalities that reduce these potentially detrimental side-effects (Bamett, 2006). For these reasons the series of investigations that have been conducted in this thesis were designed with the intent to examine areas that are critical to the preparation and recovery of soccer players. The first of five experimental chapters collated information on the use of fitness testing within English professional football. It was concluded that the practise of fitness testing players is extremely commonplace and that field-based testing protocols were far more popular an assessment method. The second experimental chapter went on to demonstrate that the most commonly used fitness test within professional football (MSFT) was sensitive enough to detect performance changes that occur as a result of training. A further finding within the context of the question was that it is possible for female players to significantly improve aerobic capabilities with additional high intensity aerobic training. The third experimental chapter investigated the effect different glycemic index high CHO diets could have on recovery of performance following 90 min of intermittent soccer type exercise. This study concluded that consuming either predominately high or low GI CHO mixed meals in the 24h recovery period between bouts of high intensity prolonged intermittent exercise had no difference on measures of performance. The final two experimental chapters went on to investigate the effects of cold water immersion on indices of muscle damage following intermittent exercise. Results from these investigations suggest that submerging individuals in 10°C water immediately following high intensity intermittent exercise reduces some but not all indices of muscle damage. In summary, fitness assessments of players are commonly made within professional football clubs. The most common test used was the MSFT and this appears to be sensitive to changes that result as a consequence of training. During recovery from high intensity intermittent exercise the importance of carbohydrates is apparent although the type of carbohydrate appears to be less important, furthermore, cold-water immersion may be effective in reducing some but not all indices of muscle damage.
108

Investigation into the potential of energy storage to tackle intermittency in renewable energy generation

Barbour, Edward January 2013 (has links)
Renewable Energy is by nature intermittent and matching the supply of energy to specific time dependent demand poses huge challenges. Energy storage is a useful tool in handling this temporal disparity, although except for regions very suitable for pumped hydroelectric storage schemes, it suffers from being technically difficult to implement and costly as a result. This study investigates the potential benefits offered by various scales of energy storage to different types of renewable energy generation. It also explores the economic drivers behind energy storage operating as part of an electricity spot market. A stochastic optimisation algorithm for determining the maximum possible arbitrage revenue available to energy storage devices is presented and schedule of operation of storage acting in this manner is analysed. The schedule of operation for maximising the revenue is compared to the schedule of operation for minimising the fuel cost to the network and it is demonstrated that because prices are more volatile than the demand which drives them, storage devices do not always act to decrease the fuel cost to the network. It is shown that storage behaving in the right manner can offer significant benefits to electricity systems, and increases the usage of base-load generation, reducing peak electricity demands and the need for expensive peaking plants. The value of storage also increases as the penetration of renewable energy generation increases, although the current electricity market framework is perhaps not the best way to encourage this behaviour. Advanced Adiabatic Compressed Air Energy Storage (AA-CAES) is also identified as a theoretical storage option which deserves further scrutiny. Using thermodynamic modelling the efficiency of this type of system is estimated in the range of 63-67%, and we suggest that this may be increased closer to 73% by using direct contact heat exchangers rather than indirect contact heat exchangers (and a separate thermal fluid), as described in the currently available literature. However, dealing with large pressure ranges (leading to large variations in pressure ratios) encountered in the expansion process is a problematic area which will have to be resolved before this type of system can be constructed with “off-the-shelf” components. Some small scale experiments are used to gain valuable insights into a AA-CAES system. While these suffer from a very low overall efficiency, they highlight the effect of variable pressure ratio on expander efficiency. We conclude that AA-CAES is thermodynamically sound and will be achieved one of two ways: either through the construction of expanders that can work with high efficiency over large pressure ratios, or by resolving the engineering issues with maintaining a constant storage pressure.
109

Effects of Click + Continuous Food Vs. Click + Intermittent Food on the Maintenance of Dog Behavior.

Wennmacher, Pamela L. 05 1900 (has links)
There is disagreement among clicker trainers on whether or not food should be delivered every time the clicker (conditioned reinforcer) is used. However, presenting a conditioned reinforcer without food can weaken the strength of the conditioned reinforcer and also disrupt its discriminative stimulus function. A within subjects reversal design was used with 2 dogs to compare the behavioral effects of continuous pairings (C+F condition) vs. intermittent pairings (C+C+F condition) of the clicker with food. Results show that the C+C+F condition affects the frequency, accuracy, topography, and intensity of the behavior, and increases noncompliance and other unwanted behaviors. This study adds to the literature by evaluating the effects of conditioned reinforcement in an applied setting using discrete trials without undergoing extinction.
110

The IL-6 system and its interaction with chronic low-grade inflammation and high intensity intermittent exercise

Leggate, Melanie January 2012 (has links)
The IL-6 system is key in the development of chronic low-grade inflammation. It is known to be upregulated in response to acute exercise and lowered at rest after exercise training. IL-6 has both anti- and pro-inflammatory properties and moderation of this cytokine could alleviate chronic low-grade inflammation which is associated with obesity and Type 2 diabetes mellitus (T2DM). This thesis investigated the interplay between inflammation, glycaemic control and high intensity intermittent training (HIIT) - an exercise regimen that has been shown to yield many health benefits. There was a greater increase in IL-6 after an acute bout of HIIT than continuous moderate intensity exercise, where external work was matched (Chapter 4). Although sIL-6R and the IL-6/sIL-6R complex were both significantly increased after acute exercise there were no differences between HIIT and moderate intensity exercise. In response to 2 weeks HIIT there was a significant reduction in IL-6 and increase in IL-6R in adipose tissue in overweight and obese males (Chapter 5). It was also determined that IL-6R present in adipose tissue is at least partly composed of the membrane-bound IL-6R isoform (Chapter 6). Reductions in circulating sIL-6R, the IL-6/sIL-6R complex, MCP-1 and adiponectin, as well as a decrease in waist circumference and increase in peak oxygen uptake during exercise were also induced after 2 weeks HIIT (Chapter 5). Young adults with T2DM (< 40 y) displayed elevated levels of inflammatory proteins in comparison to lean controls, however there were no significant differences in comparison to obese controls (Chapter 7). In conclusion, the findings of this thesis demonstrate that acute and repeated bouts of HIIT have positive effects on the inflammatory profile in the circulation and adipose tissue, particularly in relation to the IL-6 system. It should be determined if HIIT is an achievable mode of exercise for patient populations, including T2DM patients, in order to downregulate the inflammatory profile.

Page generated in 0.096 seconds