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  • 31601.
    Mustafa, Ospac Shakur
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    COMPRESSED AIR DEMAND FOR A TYPICAL BATTERY MANUFACTURING FACILITY: Optimization in operation to minimize peak power demand2020Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
  • 31602.
    Muthalagappan, Narayanan
    Högskolan Dalarna, Akademin Industri och samhälle, Energi och miljöteknik.
    Correlation of PID with other Reliability Tests for CIGS Solar Cells2014Independent thesis Advanced level (degree of Master (One Year)), 20 poäng / 30 hpOppgave
    Abstract [en]

    With solar photovoltaic plants getting larger and larger, the balance in the system is getting important. Balance of the system is necessary to get the maximum power from the system by arranging its components in an optimal way. With PV systems having high DC voltages of up to 600V in USA and 1000V in Europe, the high voltage stress induced in the system is a lot. One of the effects created due to an imbalance in the system is the Potential Induced Degradation. Previous researchers have found out that the Potential Induced Degradation (PID) is due to the voltage imbalance in the string (a schematic arrangement of solar modules in a system) which is influenced by the environmental factors. The objective of the project is to characterize the electrical properties of different available CIGS solar cell types and to correlate other reliabilty tests with PID test to find out if PID has any correlation with the other degradation mechanisms. Thus 8 samples were requested from two different manufacturers of different CIGS solar cells which were tested and results were compared and analysed. Therefore it was found out some compostional structure prove stable against the PID. But changing the combinaton of the compounds have a difference. Some relational pattern of degradation with the Stability test was evident. Few of the previous finding were again confirmed with a new path of approach for the further researches.

  • 31603.
    Muthyala, Monica
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Design and Crash Analysis of Ladder Chassis2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    A chassis is known as the carrying unit of an automobile, like the engine, transmission shaft and other parts are mounted on it. Ladder chassis has longitudinal rails which are connected along the length with crossmembers through welding or mechanical fasteners. Rectangular box section is chosen for the longitudinal rails of ladder chassis. Design modifications are done in HyperMesh to improve torsional and bending stiffness of the chassis designed in steel and CFRP. Adding of the X- bracing cross-member and ribs are few of the techniques used to provide strength to chassis. This thesis aims to produce a light-weight chassis. A combination chassis of both steel and CFRP components is created by replacing heavy steel cross-members with CFRP cross-members, which resulted in the reduction of weight by 14.6%. Crash analysis is performed to all the chassis using Radioss. Depending on the result obtained from crash analysis and values of torsional and bending stiffness, the combination chassis is selected. Thickness optimization is performed to the combination chassis. It is observed that 7.91% of weight is further reduced in the combination chassis.

    Fulltekst (pdf)
    BTH2019Muthyala
  • 31604.
    Muti, Muaz Abdul
    Blekinge Tekniska Högskola.
    Design of an Autonomous underwater drone for achieving efficiency in the operation of the sensor package during monitoring of water bodies2022Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    Background: the process of water quality monitoring is a critical quality assurance process. However, conventional methods include monitoring by a team of divers going to different depths to collect water samples. This method is expensive, time-consuming, and can lead to adverse consequences like a fatality. 

    Objectives: This study aimed to develop a robust, autonomous prototype for water quality monitoring. The idea was to measure water quality at a depth of 20 meters by designing an unmanned underwater drone with sensors for measurement and tracking. 

    Methods: a detailed literature review was conducted and trend watching, tech watching, and benchmarking were some strategies used to extract design ideas. After creating a good scope, various design ideas were iterated to solve the problem. Two concept designs of the underwater drones were selected and evaluated by a discussion matrix. The design idea that best fit the project requirements was selected and produced. Stress analysis was performed on the final design to check design performance at a depth of 20 meters. 

    Results: Design Fish 2 was chosen as the final design of the prototype. The selected design is manufactured from S316 stainless steel which is the material used for the shell while the rest is PLA. 

    Conclusion: The prototype has a hollow, cylindrical body that provides low hydrodynamic resistance, and the vertical design provides better stability when moving underwater. 

    Fulltekst (pdf)
    fulltext
  • 31605.
    Mutwali, Reem
    Högskolan Dalarna, Institutionen för information och teknik.
    The influence of the built environment on the climate in different Swedish urban fabrics2023Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    The urban heat island effect is usually disregarded when considering energy-efficient measures for the built environment. This study aims to present and analyze the effect of the urban built environment on the Swedish urban climate. This analysis is done in terms of assessing the mean urban heat island and monthly average air temperature. Different urban fabrics were studied from Goteborg and Stockholm using Goteborg weather as reference weather data. The geographical information system (QGIS) is used to generate the morphological and land coverdata of the study areas. The UWG model is used to estimate the air temperature difference between the reference data and the study areas. This difference is referred to as the UHI intensity. It is also used to perform a sensitivity analysis considering 6 urban parameters namely: site coverage ratio, average building height, façade-to-site ratio, tree coverage, grass coverage,and surface albedo. The results showed that areas with a high site coverage ratio experienced higher monthly mean UHI intensity in summer and winter. The night-time monthly mean urban heat island for sites with the highest site coverage ratio was 2.0 O C in summer and 0.35 O C in winter. The vegetation cover (trees and grass) —although it is likely due to the limitation of the representation of the shadowing effect of trees in the model —and surface albedo have the least effect on the monthly mean UHI. The influence of the average building height and façade to site ratio is moderate and depends on the shape of the urban canyon which is highly simplified in the UWG model. The future prediction of the monthly mean air temperature showed an increase of 1.1 O C forcompact sites in summer and 0.9 to 1.0 O C in open sites. In winter the average monthly airt emperature will increase by 1.8 to 2.0 O C in different urban textures. There will be an increase of 0.3 O C in mean urban heat island in summer and a 0.2 increase in winter by 2070.

    Fulltekst (pdf)
    fulltext
  • 31606.
    Muwumuza, Linda
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik. KTH Royal Institute of Technology.
    Social and Environmental effects of Bujagali Dam2014Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Abstract

    There has been a steady increment in economic growth in Uganda and as the economy is on the rise, the demand for energy also increases. Hydro power energy production has been growing in Uganda as a result of the different types of dams created in Uganda along the River Nile. Uganda has been trying to reach the target of electricity capacity so as to ensure that her people get the energy required to improve on their livelihoods. Uganda as a whole has different energy sources but in this thesis, Bujagali dam will be at the center of the focus. Looking at the social and environmental impacts made upon its construction in Jinja.

    The main objective of this thesis was therefore to show how the livelihoods of the people dwelling in the neighborhood and the environment were affected by the construction of the dam. The livelihoods of the people before the construction of the dam were reviewed in regard to their social life as well as the environment from past literature provided. The different aspects in which the people and environment were affected after the construction of the dam were also reviewed through different interviews with the residents of Bujagali.  

    There were both positive and negative effects, socially, environmentally and economically due to the construction of the Bujagali. The positive social effects were: provision of land for farming, provision of employment opportunities for the residents, increase in tourism at the dam, the falls and the cultural centers, community development including education, health facilities, skill training, water supply and power supply while the negative effects were loss of land, cultural loss, and less access to different points of the river for fishing purposes for the residents.

    The positive environmental effects were increase in fish species, more health and safety awareness, and thermal plants closure hence less green house gases effects on the ozone layer, the noise levels effects due to the dam construction, were of no consequence as they were in the required standard.  The negative environmental effects were majorly water levels fluctuation that affects the head of water which in turn affects the capacity of power produced at the dam and air quality of the area during and after the construction of the dam especially air emissions.

    The positive economic effects were: increment of power to the national grid, lower electricity costs, closure of thermal plants as they were expensive to run and maintain and reduction of load shedding. The negative effect was the financial loan that the government of Uganda obtained to construct the dam that has to be paid back. 

    Fulltekst (pdf)
    fulltext
  • 31607.
    Muñoz García, Marina
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap.
    Hurtado Sierra, Juan Carlos
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap.
    Structural analysis of the 17th century warship Vasa: Influence of the dowels on the stiffness of the hull2014Independent thesis Advanced level (degree of Master (One Year)), 20 poäng / 30 hpOppgave
    Abstract [en]

    After 333 years under depths of the Baltic Sea, the warship Vasa was salvaged and nowadayslies in a dry dock inside the Vasa Museum in Stockholm. Its current support system, which consists on eighteen cradle-stanchions pairs of steel, is not able to handle the present loads in a satisfactory manner. Experimental tests showed that the Vasa's hull is gradually deforming mainly due to creep behavior.

    Thus, in order to preserve the Vasa for future generations, a new support system has to be implemented in a foreseeable future. There are several factors to take into consideration for its construction, which are: the degradation of the oak, its current mechanical properties and its inhomogeneity in addition to the climatic conditions of the Museum and the impossibility of taking unlimited specimens for its analysis. Hence, it is crucial to investigate the areas where the stresses and deformations are critical in the ship and how affected is the stiffness of the hull, its most important component.

    In this dissertation work two Finite Element Analyses are accomplished. The first study consists on the creation of a superelement of a section of Vasa's hull with the intention of investigating the influence of the dowels on the stiffness of the hull. In the second analysis a simplied model of the entire warship Vasa is created in order to analyze it and locate possible critical areas on the hull due to its own weight and the stresses originated by the support system. The software selected for these simulations are Abaqus and CreoSimulate 2.0.

    From the first study it is concluded that that the dowels do not have a signicant influence in the stiffness coeffcients of the hull. The second analysis determines that the maximum stresses are located on the bottom part of the hull. This dissertation work concludes with a suggested future work.

    Fulltekst (pdf)
    Structural analysis of the 17th century warship Vasa
  • 31608.
    Muñoz Rocha, Angel
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap.
    Morilla Cabello, Pablo
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap.
    Investigating the robot pool from a cyber-physical production system perspective2023Independent thesis Basic level (degree of Bachelor), 20 poäng / 30 hpOppgave
    Abstract [en]

    The current industry landscape is witnessing a trend towards high-mix production, which requires a reconsideration of the existing production systems. Although high levels of automation have been achieved in the industry, the traditional automated production line, designed for mass production of homogeneous goods, is not well-suited for high-mix production. To address this situation, flexible and adaptable alternatives have been sought to replace the inflexible and rigid traditional production lines.

    One of the proposed solutions is the combination of digital technology and physical automation, creating a highly connected and intelligent production environment. Such an environment requires the implementation of a cyber-physical production system that integrates Industry 4.0 technologies, such as Automated Guided Vehicles (AGVs) and flexible robots. This system enables a set of robots to perform different tasks instead of being exclusively dedicated to a specific task, making it moreadaptable and flexible.

    The integration of advanced technologies, such as AGVs and Cyber-Physical Production Systems (CPPS), can significantly enhance workflow optimization, reduce production times, and enable flexible layout adaptations to cater to the specific requirements of different products in the production line. Furthermore, it can facilitate better control of information and enable real-time monitoring of the production process, leading to improved production efficiency and quality.

    To demonstrate the potential of such a system, a virtual commissioning of a fully innovative production line has been carried out, encompassing all the previously mentioned technologies and elements. The virtual commissioning of the production line serves as a proof-of-concept for the cyber-physical production system and its ability to provide a highly connected, intelligent, and adaptable production environment.

    Fulltekst (pdf)
    fulltext
  • 31609.
    Mwaba, MG
    et al.
    Carleton University, Ottawa, Canada.
    Golriz, Mohammad R
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Gu, J
    Carleton University, Ottawa, Canada.
    A semi-empirical correlation for crystallization fouling on heat exchange surfaces2006Inngår i: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 26, nr 4, s. 440-447Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Crystallization fouling experiments are reported in this paper. In general the results show four distinct time regions: a region where the fouling thermal resistance is zero, a region where the fouling thermal resistance is negative, a region where the fouling resistance increases steadily and a region where the fouling thermal resistance remains constant. Each of these regions can be matched with different development phases in the crystallization fouling process: nucleation phase (regions 1 and 2), growth phase and asymptotic phase. Overall the fouling curves exhibit an S-curve, characteristic of the logistic curve. A new correlation based on the solution of the logistic equation is formulated. The correlation parameters are evaluated and related to the crystallization parameters. The results of this work can find application in predicting the evolution of the fouling scale layer in heat exchangers that are in operation. The predictions can assist heat exchanger operators to plan cleaning schedules.

  • 31610.
    Mwakyanjala, Moses
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Software-Defined Radios for Satellite Ground Stations: Literature Survey2020Rapport (Annet vitenskapelig)
    Abstract [en]

    This report presents a literature survery on software-defined radio (SDR) technology and commercial-off-the-shelf (CoTS) SDR frontends. The survey on SDR technology covers hardware components with special emphasis on signal processing devices. On the other hand, the survey on CoTS covers two SDR platforms that are considered for the development of a software defined satellite ground station. This development is part of a project jointly hosted by Luleå Tekniska Universitet (LTU) and the Swedish Space Corporation (SSC). It is titled "Advanced Software Dened Radio technology for new satellite ground equipmentarchitecture".

    Fulltekst (pdf)
    fulltext
  • 31611.
    Myhr, Ulla
    et al.
    Boden College of Health and Caring Sciences.
    von Wendt, Lennart
    University of Gothenburg, Department of Handicap Research.
    Sandberg, Karl W.
    Boden College of Health and Caring Sciences.
    Assessment of sitting in children with cerebral palsy from videofilm: A reliability study1993Inngår i: Physical & Occupational Therapy in Pediatrics, ISSN 0194-2638, E-ISSN 1541-3144, Vol. 12, nr 4, s. 21-35Artikkel i tidsskrift (Fagfellevurdert)
  • 31612. Myhre, M
    et al.
    Moyroud, F
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM).
    Numerical investigation of the sensitivity of forced response characteristics of bladed disks to mistuning2003Konferansepaper (Fagfellevurdert)
  • 31613.
    Myhren, Jonn Are
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Byggteknik.
    Heier, Johan
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Hugosson, Mårten
    Högskolan Dalarna, Akademin Industri och samhälle, Företagsekonomi.
    Zhang, Xingxing
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    The perception of Swedish housing owner’s on the strategies to increase the rate of energy efficient refurbishment of multi-family buildings2020Inngår i: Intelligent Buildings International, ISSN 1750-8975, E-ISSN 1756-6932, Vol. 12, nr 3, s. 153-168Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Improving the energy performance of existing buildings is crucial for reaching both EU and national climate and energy targets. The main objective of this study was to map challenges that Swedish housing owners perceive when making energy-efficiency refurbishments. A secondary objective was to compare how well these challenges relate to national strategies. The study applied a combined methods approach with audience response meters and in-depth qualitative semi-structured interviews. The housing owners express the view that they have sufficient knowledge of national ambitions to improve the energy performance of buildings and welcome the new building regulations. Despite this supposed knowledge and the current economic situation with beneficial loans, the refurbishment rate still remains low. The housing owners explain that they are concerned about the ‘performance gap’ and request more accurate energy performance predictions. They are also waiting for proof that all sustainability goals can be reached in reality. Probably, too few projects fulfilling ambitions in all categories: economically, socially and energy-wise have been followed up and demonstrated nationally. The new national information centre on refurbishment of buildings may help to spread information about such projects, raise awareness and thus increase the refurbishment rate.

    Fulltekst (pdf)
    fulltext
  • 31614.
    Myhren, Jonn Are
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Byggteknik.
    Olofsson, Thomas
    Högskolan Dalarna, Akademin Industri och samhälle, Byggteknik.
    Bergdahl, Martin
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Lågtemperaturuppvärmning med tilluftsradiatorer och värmeåtervinning i frånluft: en varsam renovering av flerbostadshus för energieffektivisering2014Rapport (Annet vitenskapelig)
    Abstract [sv]

    För att nå reella sänkningar av energianvändningen i hela byggnadsbeståndet krävs tillgång till kostnadseffektiva renoveringspaket med energieffektiva systemlösningar där samspel mellan installationssystem och byggnad beaktas.

    Denna förstudie belyser möjligheter med alternativa renoveringspaket med lågtemperatur-tilluftsradiatorer och värmeåtervinning i frånluften (FX). Systemkombinationer och jämförelser har gjorts med mera etablerade lösningar med traditionella radiatorer, balanserad mekanisk ventilation (FTX) och solvärme. Mindre prövade lösningar såsom frånluftsmoduler (VBX) kopplat till befintliga värmepumpar och behovsstyrd ventilation undersöktes också.

    Energianvändning och kostnadseffektivitet med de undersökta åtgärdspaketen prövades för två äldre bostadshus med vardera specifika restriktioner: den ena inom fjärrvärmenätet och det andra ett K-märkt hus utanför fjärrvärmenätet. Samtidigt reflekterades det över vilka tekniska lösningar som samtidigt är gynnsammast ur hållbarhetssynpunkt. För flertalet befintliga byggnader behöver såväl metoder som komponenter utvecklas på ett varsamt sätt som uppfyller båda ägarens krav som övergripande mål baserat på systemförutsättning och kostnadseffektivitet.

    Förstudien visar att:

     lågtemperatur-tilluftsradiatorer är en systemkomponent som möjliggör ökad komfort via förvärmning och filtrering av inkommande ventilationsluft, effektivare värmeproduktion och minskning av värmeförluster i distribution av varmvatten. Renovering med installation av FX-system i kombination med lågtemperatur-tilluftradiatorer är ett alternativ till FTX system som begränsar byggåtgärderna i byggnaden och ger lägre livscykelkostnad

     Byggnadsskalets täthet blir avgörande för energinyttan båda med FX- och FTX-system. Förstudien visar att FX-system är fördelaktig i byggnader med dålig lufttäthet

     I byggnader med befintligt frånluftssystem kan behovsstyrning av ventilationen vara ett enkelt och kostnadseffektivt sätt att sänka ventilationsförlusterna och spara energi som alternativ till att installera återvinningssystem

    Förstudien visar klart att energieffektiv renovering kan åstadkommas med val av varsamma metoder som också åstadkommer ökad komfort och systemnytta, utanför såväl som inom fjärrvärmenätet. Samtidigt kan ägarens krav på kostandsnytta nås och byggnaders bevarandekrav uppfyllas.

    Nu krävs det demonstrationsprojekt för att inte minst sprida kunskap i branschen men också applicering på större bostadsområden.

    Fulltekst (pdf)
    fulltext
  • 31615.
    Myhrman, Christopher
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013).
    Optimering av hydraulsystem på pappershanteringstruck2013Independent thesis Basic level (university diploma), 15 poäng / 22,5 hpOppgave
    Abstract [sv]

    Det här examensarbetet inom Maskiningenjörsprogrammet på Karlstad universitet har utförts på Linde Material Handling AB i Örebro. Arbetet inleddes med att en kundundersökning utfördes genom en enkät till personal på Stora Enso Skoghall. Enkäten innehöll relevanta frågor om hur kunden upplever sina truckar från Linde, hur service och underhåll fungerar, samt hur de skulle vilja förbättra truckarna inför framtiden.

    Utifrån kundundersökning hos Stora Enso uppdagades det bl.a. att hydrauliken i klämaggregatet går för långsamt och att detta är ett störande moment som medför irritation bland truckförarna. Frågeställningen blev, hur väl anpassat klämaggregatet är till truckens hydrauliska funktion utifrån dagens krav på klämkraft och fart. Hydrauliken hos truckar som byggs idag är mycket förfinad gentemot äldre system och kan leverera högre hydraultryck. Med ett högre hydraultryck kan samma klämkraft uppnås med en mindre cylinderdiameter.

    Arbetet har gått ut på att undersöka och kartlägga förluster i lasthanteringshydrauliken, samt att om möjligt minska dessa. Arbetet har avgränsats till att undersöka hydraulsystemet för klämhydrauliken, från truckens ventilblock, genom masten och ut till aggregatet. Aggregatets hydraulcylindrar ingick i undersökningen, även utvärdering av dess dimension, med mål att minimera tiden från öppet till stängt aggregat.

    Resultatet av experiment och beräkningar visar att slangvindan, och tillhörande slangledningar, för klämfunktionen är underdimensionerad och ger upphov till en stor värmeeffekt som ger energiförluster i form av onödig uppvärmning av hydrauloljan. Genom grövre dimensionering av slangvindan kan besparingen på ett år uppnå till 9 m

    3 dieselbränsle, motsvarande cirka 126 000 Skr. Detta beräknat på att utlastningstruckarna på Stora Enso Skoghall hanterar 700 000 ton kartong per år. Ur miljöperspektiv skulle bränslebesparingen motsvara cirka 22 ton fossil koldioxid.

    För att öka farten från öppet till stängt aggregat finns möjligheten att minska hydraulcylindrarnas diameter och på så vis minska tiden från öppet till stängt aggregat, från 5,7 s till cirka 3,6 s, samtidigt som erforderlig klämkraft uppnås.

    Fulltekst (pdf)
    Optimering hydraulsystem
  • 31616.
    Myhrman, Nils
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Andersson, Sebastian
    Mälardalens högskola, Akademin för innovation, design och teknik.
    ÅTGÄRDER FÖR SÄNKNINGEN AV UNDERHÅLLKOSTNADER FÖR MATERIALTRANSPORTÖRER: En fallstudie på Volvo GTO Powertrain2016Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [en]

    The purpose of the study is to investigate in the possibilities to lower the maintenance cost for material transporters without having an effect on the quality on the environment where there is a variation in quantities and versions of products. To best fulfill the requirement of the purpose of the study, following questions have been defined. 1. Which factors has the greatest effect on the cost of maintenance for the material transporters? 2. Which factor or factors have the biggest impact and how could they be tackled? 3. How can it be solved without binding to much capital? The work with the study has been done with case study at Volvo GTO Powertrain, combined with literature studies. The work with the case study has been with the method DMAIC to achieve the most satisfactory result. The field of literature is within the field of logistics with focus on flows, transports and maintenance. The study has showed the problems causing the high maintenance cost. The costs for a truck set came to an amount of 405313 SEK for the years 2013-2015. To solve the problem with the high maintenance costs, changes in packaging where made to diminish the burden of one of the trucks in the trucks set that have high maintenance costs. Several solutions were also made to improve the situation for the trucks, but there were ergonomical factors involved. Suggestions on which articles and their package solution that are affected by the solution and the effects of these changes on current production have been presented. In regards of the case study sole study object, it is desirable if a similar case studies could be made at another company. The reason lies in the unique assembly line that is elevated and therefore requires custom made trucks. Despite the uniqueness of the assembly line, the framework for continues improvements has been marked out and we strongly recommend further work and researches.

    Fulltekst (pdf)
    fulltext
  • 31617.
    Mylavarapu, Goutham
    et al.
    Aerospace Engineering, University of Cincinnati.
    Mihaescu, Mihai
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Fuchs, Laszlo
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Papatziamos, Georgios
    Karolinska Hospital.
    Gutmark, Ephraim
    Aerospace Engineering, University of Cincinnati.
    Planning human upper airway surgery using Computational Fluid Dynamics2013Inngår i: Journal of Biomechanics, ISSN 0021-9290, E-ISSN 1873-2380, Vol. 46, nr 12, s. 1979-1986Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The study advances the idea of using computational fluid dynamics in the process of planning surgical treatment modalities for patients with obstructive airway disorders. It is hypothesized that the a priori knowledge of the functional outcome of surgical intervention on the flow and airway resistance can guide the surgeon in choosing an effective surgical strategy. Computed tomography images spanning the respiratory tract of an adult patient with a combined glottic and subglottic stenosis are used to reconstruct three-dimensional geometrical models of the airway. Computational fluid dynamics is used to obtain airway flow patterns during inspiration and expiration in these models. Numerical predictions about flow velocity, pressure distribution on the airway lumen, wall shear stress, and airway resistance are obtained so that the relevance of each individual stenotic level is quantified. Four different virtual surgeries in different combinations are assessed in order to remedy the constricted airway. The virtual surgery based airway models are evaluated by comparisons with the pre-treatment flow modeling results. The predicted numerical data revealed that the removal of the constriction at the level of the vocal folds will have the most significant effect on the airway resistance. The flow simulations offer a quantitative method of evaluating the airway resistance in patients with combined glottic and subglottic stenoses. Predictions of airway resistances and other numerical calculations from different virtual surgeries give additional inputs for the surgeon, in deciding the most appropriate surgery on a case-by-case basis.

  • 31618.
    Mylavarapu, Goutham
    et al.
    Aerospace Engineering, University of Cincinnati.
    Mihaescu, Mihai
    Aerospace Engineering, University of Cincinnati.
    Gutmark, Ephraim
    Aerospace Engineering, University of Cincinnati.
    Fuchs, Laszlo
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Papatziamos, Georgios
    Karolinska Hospital Solna.
    Virtual Surgery: a Computational Engineering Approach to a Medical Problem2010Inngår i: proceedings of International Conference on Jets, Wakes and Separated Flows ICJWSF-2010, 2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The aim of the study is to utilize Computational Fluid Dynamics in the process of planning surgical treatment modalities for patients with obstructive airway disorders. It is hypothesized that the a-priori knowledge of the functional outcome of surgical intervention on the flow and airway resistance can guide the surgeon in choosing an effective surgical strategy. Computed Tomography images spanning the respiratory tract of an adult patient with a combined glottic and subglottic stenosis are used to reconstruct three-dimensional geometrical models of the airway. Computational Fluid Dynamics is used to obtain airway flow patterns during inspiration and expiration in these models. Numerical predictions about flow velocity, pressure distribution on the airway lumen, wall shear stress, and airway resistance are obtained so that the relevance of each individual stenotic level is quantified. Four different virtual surgeries in different combinations are assessed in order to remedy the constricted airway. The virtual surgery based airway models are evaluated by comparisons with the pre-treatment flow modeling results. The predicted numerical data revealed that the removal of the constriction at the level of the vocal folds will have the most significant effect on the airway resistance. The flow simulations offer a quantitative method of evaluating the airway resistance in patients with combined glottic and subglottic stenosis. Predictions of airway resistances and other numerical calculations from different virtual surgeries give additional inputs for the surgeon, in deciding the most appropriate surgery on a case-by-case basis.

  • 31619.
    Mylavarapu, Goutham
    et al.
    Aerospace Engineering, University of Cincinnati.
    Mihaescu, Mihai
    Aerospace Engineering, University of Cincinnati.
    Gutmark, Ephraim
    Aerospace Engineering, University of Cincinnati.
    Murugappan, Shanmugam
    Otolargyngology, Head and Neck Surgery, University of Cincinnati-Medical Center.
    Kalra, Maninder
    Cincinnati Children's Hospital.
    Fluid-Structure Interaction Analysis in Human Upper Airways to Understand Sleep Apnea2010Inngår i: 48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition, AIAA , 2010, s. 2010-1264-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Sleep apnea is characterized by partial or complete obstruction of upper airway during sleep. Existing clinical therapies are not fool-proof. Understanding human upper airway mechanisms with flow and structure dynamics is hence, essential for designing better clinical therapies. In this study, two dimensional Fluid-Structure Interaction (FSI) simulations were carried on human upper airway models using ADINA 8.4, a finite element code. Baseline model (B) is reconstructed from a mid-sagittal Magnetic Resonance Image (MRI) of an adolescent. In-house developed MATLAB code is used to de-feature various structures on the MRI scan. Vertices information from MATLAB code is then imported into Gambit 2.2, where edges are reconstructed and exported in IGES format to ADINA. Fluid and Solid surfaces are reconstructed and discretized in ADINA. Flow was assumed laminar and incompressible. Plain Strain hypothesis and small strains were assumed with solid domain. Appropriate boundary conditions with wall and fluid structure interfaces were defined in both fluid and solid domains. Pressure drop across airway is varied incrementally with a user defined time function. Airway wall displacement and flow features are obtained. The displacement of tip of soft palate and critical closing pressures required for partial or complete closure of upper airways are computed and compared across different cases. For comparative studies between a normal, narrower and corrected airway models (A, B, C), Model B is reconstructed from Model A by moving its posterior airway wall in anterior direction and Model C is reconstructed from Model B by excising the length of soft palate by 30%. It was observed that airway is more susceptible to collapse during expiration phase than inspiration. Increasing the stiffness of soft palate as in a palatal implant clinical therapy showed significant improvement in airway potency as demonstrated in Models A and B. Model B demonstrates a case of complete obstruction for significantly lower closing pressures when compared to Model A. Model A demonstrated hypo-apnea or partial obstruction of airway. Model C with excised soft palate is less susceptible to airway collapse when compared to Model B. This study is step forward to our previous studies on upper airways where airway walls were assumed static.

  • 31620.
    Mylavarapu, Goutham
    et al.
    Aerospace Engineering, University of Cincinnati.
    Mihaescu, Mihai
    Aerospace Engineering, University of Cincinnati.
    Gutmark, Ephraim
    Aerospace Engineering, University of Cincinnati.
    Murugappan, Shanmugam
    Otolargyngology, Head and Neck Surgery, University of Cincinnati-Medical Center.
    Prahl Wittberg, Lisa
    Dept. Energy Sciences, Division of Fluid Mechanics, Lund University.
    Fuchs, Laszlo
    Dept. Energy Sciences, Division of Fluid Mechanics, Lund University.
    Papatziamos, Georgios
    Karolinska Hospital Solna.
    Importance of paranasal sinuses in computational modeling of nasal airflow2009Inngår i: 47th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, AIAA , 2009, s. 2009-0772-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper investigates the importance of including paranasal sinuses in the computational modeling of the nasal airflow. Three dimensional models of human nasal airway with and without including paranasal sinuses were reconstructed from Computed Tomography (CT) axial images of a subject with healthy nasal airway. The reconstruction process was performed using MIMICS® software program. The airway volume was discretized using TGRID® mesh generator. Steady Reynolds-Averaged Navier-Stokes (RANS) simulations were carried in both inspiratory and expiratory phases of respiratory cycle at a peak flow rate of 15 L/min in FLUENT®. The results show that the left and right nasal resistances change with less than 11% when paranasal sinuses are included in the computational model of the nasal airway. The flow into the sinuses is characterized by very low velocities during both inspiration and expiration conditions. The velocity distributions in the main nasal passage show small change predominantly in regions closer to the paranasal sinuses when compared to the model where sinuses were not included.

  • 31621.
    Mylavarapu, Goutham
    et al.
    Aerospace Engineering, University of Cincinnati.
    Mihaescu, Mihai
    Aerospace Engineering, University of Cincinnati.
    Gutmark, Ephraim
    Aerospace Engineering, University of Cincinnati.
    Murugappan, Shanmugam
    Otolargyngology, Head and Neck Surgery, University of Cincinnati-Medical Center.
    Zimmer, Lee
    University of Cincinnati-Medical Center.
    Seiden, Allen
    University of Cincinnati-Medical Center.
    Computational Fluid Dynamics modeling of nasal airflow to understand drug delivery process2010Inngår i: 40th AIAA Fluid Dynamics Conference, AIAA , 2010, s. 2010-4735-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Computational Fluid Dynamics (CFD) is often used in multidisciplinary studies like respiratory flows in understanding the flow mechanisms and in optimizing therapeutic and surgical treatments in patients with respiratory disorders. This study is one such attempt to understand nasal drug delivery processes. Three dimensional anatomically accurate nasal airway model is reconstructed from axial Computed Tomography (CT) scans of a patient using MIMICS®. Computational volume for the nasal airway model is discretized using TGRID® and Gambit®. Flow and Particle tracking simulations are carried for a range of peak inspiratory flow rates 7.5, 15, 30, 45 and 60 lpm and particle diameters in range of 0.5 -30 μm using commercial CFD package FLUENT®. Flow field is solved using a steady RANS k-ω SST turbulence closure model. For discrete phase modeling (DPM), a stochastic random walk model with a random eddy life time is used for turbulent dissipation. Effect of particle deposition efficiencies in nasal airway with several factors like particle diameter, particle density, turbulence intensity, injection types, flow rate, spray half-cone angles were studied. Increase in particle diameter, particle diameter or flow rate or all increases impaction factor and also chances of total particle deposition. Increase in turbulence intensities shows only small improvement in particle deposition and that too for smaller particle diameters only (<10 μm). Modes of particle injection studied in this report have not so significant improvement in terms of total deposition; however local deposition varies with modes of injections. In spray injection, half cone-angles appear to have little influence on total particle depositions.

  • 31622.
    Mylavarapu, Goutham
    et al.
    Aerospace Engineering, University of Cincinnati.
    Murugappan, Shanmugam
    Otolaryngology, Head and Neck Surgery, University of Cincinnati-Medical Center.
    Mihaescu, Mihai
    Aerospace Engineering, University of Cincinnati.
    Kalra, Maninder
    Cincinnati Children's Hospital.
    Khosla, Sid
    Otolaryngology, Head & Neck Surgery, University of Cincinnati-Medical Center.
    Gutmark, Ephraim
    Aerospace Engineering, University of Cincinnati.
    Validation of computational fluid dynamics methodology used for human upper airway flow simulations2009Inngår i: Journal of Biomechanics, ISSN 0021-9290, E-ISSN 1873-2380, Vol. 42, nr 10, s. 1553-1559Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An anatomically accurate human upper airway model was constructed from multiple magnetic resonance imaging axial scans. This model was used to conduct detailed Computational Fluid Dynamics (CFD) simulations during expiration, to investigate the fluid flow in the airway regions where obstruction could occur. An identical physical model of the same airway was built using stereo lithography. Pressure and velocity measurements were conducted in the physical model. Both simulations and experiments were performed at a peak expiratory flow rate of 200L/min. Several different numerical approaches within the FLUENT commercial software framework were used in the simulations; unsteady Large Eddy Simulation (LES), steady Reynolds-Averaged Navier-Stokes (RANS) with two-equation turbulence models (i.e. kε, standard kω, and kω Shear Stress Transport (SST)) and with one-equation Spalart–Allmaras model. The CFD predictions of the average wall static pressures at different locations along the airway wall were favorably compared with the experimental data. Among all the approaches, standard kω turbulence model resulted in the best agreement with the static pressure measurements, with an average error of ∼20% over all ports. The highest positive pressures were observed in the retroglossal regions below the epiglottis, while the lowest negative pressures were recorded in the retropalatal region. The latter is a result of the airflow acceleration in the narrow retropalatal region. The largest pressure drop was observed at the tip of the soft palate. This location has the smallest cross section of the airway. The good agreement between the computations and the experimental results suggest that CFD simulations can be used to accurately compute aerodynamic flow characteristics of the upper airway.

  • 31623.
    Myrberg, Emil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Industriell ekonomi, Elektro- och Maskinteknik.
    Rudenstam, Simon
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Industriell ekonomi, Elektro- och Maskinteknik.
    Robotgradning: En förstudie för automatisering av gradnings- och slipningsprocesser i syfte att förbättra ergonomi2021Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Siemens har uppmärksammat problem med ergonomi i sina gradnings- och slipningsprocesser. Detta fastställs genom nulägesanalys som består av intervjuer med lagledare, enkäter för operatörer och observation. Under nulägesanalysen noterades vibrationer från verktygen som ett omfattande problem vilket resulterar i att cirka 50% av arbetstiden ägnas åt pauser. För att minska vibrationerna och därmed också stillastående tid evaluerades möjligheten att implementera en automatisk lösning i form av en robot. Robotar existerar i två former: traditionella industriella robotar och kollaborativa robotar, även kallade cobotar. Skillnaderna mellan de två är bland annat att industriella robotar programmeras av externa företag, de arbetar snabbare än cobotar och de kräver ett bås för att få användas. Cobotar, å andra sidan, kan programmeras av företaget själva och kan arbeta jämsides med operatörerna. Verktyget Wandelbots Tracepen identifierades som ett sätt att ytterligare förenkla programmeringen av cobotar. Med denna information i åtanke identifierades processer i verkstaden som är lämpligast för automatisering, dessa är rillslipning av inner och yttermantel på SGT-800 och impingement på SGT-800. Andra processer som inte är av typen gradning och slipning noterades också som automatiseringsbara, men undersöktes inte ytterligare i denna studie. För att fastställa vilken robottyp som är mest optimal för ändamålet undersöktes skillnaderna mellan industriella robotar och cobotar ytterligare, bland annat genom intervjuer med Sveriges Forskningsinstitut och ARHO som båda är specialister på robotintegration. Cobotar fastställdes som bättre lämpade till följd av deras användarvänlighet och flexibilitet samt de utvalda processernas utdragna men enkla utförande. Vid identifiering av optimal robotmodell användes en beslutsmatris där prestanda, pris och användarvänlighet vägdes in. Två robotar från företaget Universal Robots ställs moten robot från ABB. Modellen UR-10e från Universal Robots fastställdes som bäst lämpad och visualiserades därmed i en robotcell med hjälp av 3D-programmet Siemens NX12. Slutsatsen som kunde dras från studien var att investering av en cobot hade haft en positiv effekt på förbättringen av operatörernas ergonomiska problem samt eliminerat deras frekventa pauser. Vidare hade teknologisk arbetslöshet undvikits eftersom cobotar är designade för arbete jämsides med mänskliga operatörer och avlägsnar därmed även säkerhetsfrågorna associerade med traditionella robotar. Däremot krävs fortsatt arbete, som nämns i slutet av studien, innan implementering av rekommenderat lösningsförslag. 

  • 31624.
    Myrelid, Paulina
    Chalmers University of Technology, Gothenburg, Sweden.
    Information quality deficiencies in delivery schedules and their impact on production scheduling2017Inngår i: Production planning & control (Print), ISSN 0953-7287, E-ISSN 1366-5871, Vol. 28, nr 3, s. 232-243Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purpose of this paper is to explore how different delivery schedule characteristics affect the quality of shared delivery schedule information and, in turn, how deficiencies in quality affect a supplier’s production scheduling process. It describes a case study conducted in the Swedish automotive industry involving a supplier that operates as the first-, second- and third-tier supplier to an original equipment manufacturer. The study reveals how four delivery schedule characteristics–namely, receiving frequency, planning period, frozen period and demand variation–create information quality (IQ) deficiencies in five dimensions of IQ: completeness, conciseness, reliability, timeliness and credibility. At the same time, it demonstrates how such deficiencies affect the supplier’s production scheduling process by requiring additional rescheduling, reworking and follow-up activities as well as additional capacity problems, safety time, safety stock and backlogs. In effect, the paper extends previous IQ-related research by considering IQ in delivery schedules.

  • 31625.
    Myrelid, Paulina
    et al.
    Mälardalens universitet, Akademin för innovation, design och teknik, Innovation och produktrealisering. Chalmers, Sweden.
    Jonsson, Patrik
    Chalmers, Sweden.
    Kaipia, Riikka
    Chalmers, Sweden.
    Wänström, Carl
    Chalmers, Sweden.
    Towards differentiated information sharing in supplier relations: Contextual considerations of information utilisation2017Inngår i: Proceedings of the annual EurOMA conference 2017, 2017Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    How to share and use information in a supply chain to improve operations planning and control (OPC) in the automotive industry is explored from the viewpoint of suppliers. The purpose is to investigate how context characteristics from portfolio models can be used for information sharing purposes and explore how intended usage of shared information at a supplier is connected to context. Case research of five suppliers revealed context characteristics that define the intention to use shared supply chain information. Information sharing differentiation through supplier relations clustering is presented as propositions and can be empirically tested in further research. 

  • 31626.
    Myrman, Alexander
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013).
    Modulerbart matarverk för CamCoil2014Independent thesis Basic level (university diploma), 180 hpOppgave
    Abstract [sv]

    Det här är ett examensarbete som går ut på att konstruera ett modulerbart matarverk för bandstålsindustrin. Examensarbetet görs på företaget CamCoils förfrågan. Som underlag och inspiration fanns ett matarverk som tagits fram i examensarbetet ”Matarverk för Camcoil” som tidigare gjorts åt CamCoil.

    CamCoil är ett nystartat produktbolag som bygger på deras haspelsystem med samma namn. CamCoil vill komplettera detta haspelsystem med ett matarverk för att bland annat bli mer konkurrenskraftiga på marknaden. Matarverket har som uppgift att dra bandstålet av haspeln, som håller en rulle med bandstål, och dra bandet genom någon sorts bearbetning och mata på det nybearbetade bandstålet på en haspel i andra änden av bearbetningen. Ett matarverk består i enkelhet av roterande valsar som driver fram bandstål antingen med hjälp av att valsarna trycks ihop och på det sättet skapar friktion. Eller så drivs bandstålet fram av friktionskraften som bildas av den stora kontaktytan som bildas när bandet dras runt valsarna vilket då förstärker den kraften bandet redan dras med.

    En maskinfamilj, med flertalet olika sorters matarverk, skulle i examensarbete tas fram. Detta så att CamCoils kunder själva kan välja det verk som är bäst anpassat för dem.

    Mätbara krav att konstruera efter:

    • Produktionshastighet: 0-100 m/min                           
    • Banddrag: 0-2 ton ≈ 0-20 kN
    • Antal band i bredd: 1-2 st.
    • Plåttjocklek: 0,3-1,5 mm
    • Bandbredd: 20-350 mm

    Examensarbetet resulterade i slutändan i sju koncept med matarverk som består av valsar med diametrar på 200 och 600 mm. De olika valsstorlekarna kombineras på olika sätt i enkelmatarverk, dubbelmatarverk och S-verk och skapar på detta sätt en hel maskinfamilj.

    Enkelmatarverk och dubbelmatarverk driver fram bandstålet genom att trycka ihop valsarna och då skapar friktion mellan vals och band, friktionskraften är då beroende på tryckkraften. Vid enkelmatarverk och dubbelmatarverk är den största begränsningen ytbeläggningen som läggs på valsarna. Ytbeläggningen är till för att skapa större friktion mellan bandet och valsarna. Ytbeläggningen valdes till Slitan 95 Shore A och är ett gummi av sorten polyuretan. S-verk driver fram bandstålet genom att bandet dras runt valsarna och skapar stor kontaktyta där friktion bildas. Vid S-verk begränsas banddraget av vilket drag man har i bandet efter matarverket. S-verket förstärker banddraget som finns efter matarverket med en faktor av 3,514 vid en kontaktvinkel då bandet är lindat ett halvvarv runt två valsar.

    Matarverkens konstruktion består i slutändan främst av en övre och en undre modul. Den undre modulen varierar i höjd beroende på vilka valsar som används, medan överdelen i stort endast varierar beroende på om matarverket har en eller två drivna valsar.

    Fulltekst (pdf)
    Examensarbete
  • 31627.
    Myrna, Olena
    et al.
    Department of Agricultural Economics, Humboldt-Universität zu Berlin, Berlin, Germany.
    Odening, Martin
    Department of Agricultural Economics, Humboldt-Universität zu Berlin, Berlin, Germany.
    Ritter, Matthias
    Department of Agricultural Economics, Humboldt-Universität zu Berlin, Berlin, Germany.
    The influence of wind energy and biogas on farmland prices2019Inngår i: Land, E-ISSN 2073-445X, Vol. 8, nr 1, artikkel-id 19Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the context of the rapid development of renewable energy in Germany in the last decade, and increased concerns regarding its potential impacts on farmland prices, this paper investigates the impact of wind energy and biogas production on agricultural land purchasing prices. To quantify the possible impact of the cumulative capacity of wind turbines and biogas plants on arable land prices in Saxony-Anhalt, we estimate a community-based and a transaction-based model using spatial econometrics and ordinary least squares. Based on data from 2007 to 2016, our analysis shows that a higher cumulative capacity of wind turbines in communities leads to higher farmland transaction prices, though the effect is very small: if the average cumulative capacity of wind turbines per community doubles, we expect that farmland prices per hectare increase by 0.4%. Plots that are directly affected by a wind turbine or part of a regional development plan, however, experience strong price increases.

  • 31628.
    Myronycheva, Olena
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Characterization of Mould Fungi Growth on Scots Pine Sapwood Surfaces2019Licentiatavhandling, med artikler (Annet vitenskapelig)
    Fulltekst (pdf)
    fulltext
  • 31629.
    Myronycheva, Olena
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Bandura, Iryna
    Department of Technology Processing and Storag e of Agricultural Products, Tavria State Agrotecnological University.
    Bisko, Nina
    Department of Mycology, Institute of Botany, National Academy of Sciences of Ukraine.
    Grygansky, Andrii P.
    LF Lambert Spawn Co..
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Assessment of the Growth and Fruiting of 19 Oyster Mushroom Strains for Indoor Cultivation on Lignocellulosic Wastes2017Inngår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 12, nr 3, s. 4606-4626Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    AbstractTwelve Pleurotus ostreatus (Jacq. ex Fr.) P. Kumm and six Pleurotus pulmonarius (Fr.) Quél. strains were characterized from the National Culture Collection of Mushrooms, Institute of Botany Kholodny, National Academy of Science, Kyiv, Ukraine (IBK). The strains were grown under commercial conditions on a mixture of wheat straw and sunflower shells under both winter and summer temperatures typical for those climatic conditions. The strains were divided into three groups according to their growing patterns. Important characteristics were compared with a commercial analogue, HK-35, such as vegetative growth, generative growth, and biological efficiency (1.9- to 3.1-fold), and were recorded for strains 2251, 2292, 2316, 2319, and 2320 of P. ostreatus and 2314 of P. pulmonarius. Strains 2251, 2292, 2301, 2321 and 2323 were the most suitable for commercial production, while strains 2319 and 2320 could satisfy processing industry requirements with their high biological efficiency. Strains 2287 and 2317 produced high-quality fruit bodies but probably required a higher temperature for cultivation. Strain 2318 might be attractive for some consumers due to its unique and unusual fruit body shape. Strain 2314 was the most promising for summer cultivation, while strain 537 produced the highest quality fruit bodies.KeywordsOyster mushroom; Strain; Vegetative growth; Fruit body; Biological efficiency; Conversion Factor (CF); Asymmetry of the Fruit Body Cap (Cas)

    Fulltekst (pdf)
    fulltext
  • 31630.
    Myronycheva, Olena
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sehlstedt-Persson, Margot
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Öhman, Micael
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Distribution of low-molecular lipophilic extractives beneath the surface of air- and kiln-dried Scots pine sapwood boards2018Inngår i: PLOS ONE, E-ISSN 1932-6203, Vol. 13, nr 10, artikkel-id e0204212Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    During industrial wood drying, extractives migrate towards the wood surfaces and make the material more susceptible to photo/biodegradation. The present work provides information about the distribution, quantity and nature of lipophilic substances beneath the surface in air- and kiln-dried Scots pine (Pinus sylvestris L.) sapwood boards. Samples were taken from knot-free sapwood surfaces and the composition of lipophilic extractives, phenols and low-molecular fatty/resin acids layers at different nominal depths below the surface was studied gravimetrically, by UV-spectrometry and by gas chromatography-mass spectrometry (GC-MS). The concentration of total extractives was significantly higher in kiln-dried than in air-dried samples and was higher close to the surface than in the layers beneath. The scatter in the values for the lipophilic extractives was high in both drying types, being highest for linoleic acid and slightly lower for palmitic, oleic and stearic acids. The amount of fatty acids was low in kiln-dried boards, probably due to a stronger degradation due to the high temperature employed. The most abundant resin acid was dehydroabietic acid followed by pimaric, isopimaric, and abietic acids in both drying types. It is concluded that during kiln-drying a migration front is created at a depth of 0.25 mm with a thickness of about 0.5 mm.

  • 31631.
    Myronycheva, Olena
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sehlstedt-Persson, Margot
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Öhman, Micael
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Portable microNIR sensor for the evaluation of mould contamination on wooden surfaces2019Inngår i: Proceedings of the 2019 Society of Wood Science and Technology International Convention: Convention Theme: Renewable Materials and the Wood-based Bioeconomy / [ed] Susan LeVan-Green, Society of Wood Science and Technology (SWST) , 2019, s. 120-125Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The traditional assessment of mould growth is sometimes subjective and can differ from person to person. By applying spectroscopic tools, it is possible to create an individual fingerprint of a wooden material and create databases for obtaining more objective information related to the chemical and biological composition. Side-boards (the flat-sawn sapwood part of the log) of Scots pine were single stacked on stickers and naturally dried indoors at 20°C to an average moisture content (MC) of 4.6%. Another ten side-boards were dried in a small-scale laboratory air-circulation kiln to an average MC of 14%. Another group of side-boards were double-stacked with the bark-side surfaces of each pair turned outwards in order to get a high extractive concentration on these surfaces, and less concentration on opposite surfaces. The different flat-side surfaces were planed according to a planing-depth scheme : 0 mm (unplanned), 0.25, 0.75, and 1.75 mm depth from the surface, and the residual wood particles were collected for further analysis. The planned surfaces were exposed to a mould test, performed by spraying a spore suspension of five mould fungi on the wood surfaces followed by incubation at the temperature of 24°C and 95±3%RH for 35 days. Thereafter, the surfaces were graded according to mould growth. A portable microNIR sensor (wave-length range 900-1670 nm, step 6 nm) was used for NIRspectra detection on the surfaces after mould test, and a data matrix was created. Multivariate analysis of obtained spectra was performed. The results show that the principal component analysis (PCA) can describe and predict 99.7% of the spectroscopic data obtained. No influence of the drying method or planned depth was discovered during classification. Two mould-classes could, however, be clearly separated; no mould, and with mould growth respectively, and the separation could be detected on a 93.4% level.

    The study demonstrates that mould growth on the wooden surface could be evaluated by portable MicroNIR spectrometer, which is sensitive enough to detect chemical differences caused by fungal contamination.

    Fulltekst (pdf)
    fulltext
  • 31632.
    Myronycheva, Olena
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Poohphajai, Faksawat
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik. innoReNew, Slovenia.
    Sehlstedt-Persson, Margot
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Vikberg, Tommy
    RISE Research Institutes of Sweden, Skellefteå, Sweden.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Junge, Helmut
    ABiTEP GmbH, Berlin, Germany.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Application of GRAS Compounds for the Control of Mould Growth on Scots Pine Sapwood Surfaces: Multivariate Modelling of Mould Grade2019Inngår i: Forests, ISSN 1999-4907, E-ISSN 1999-4907, Vol. 10, nr 9, artikkel-id 714Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Research Highlights: In this study, the Generally Recognised as Safe (GRAS) compounds were applied in order to study mould-fungi growth on dried Scots pine sapwood. Background and Objectives: The transition to the use of more sustainable wood-material may be possible by applying GRAS compounds that can control and prevent contamination by primary colonising mould fungi. Materials and Methods: Kiln-dried sawn timber was treated with three different GRAS compounds, and different fungal inoculation methods applied in order to investigate differences in the development of fungal communities. Results: Substances based on potassium silicate significantly reduced fungal growth and mould contamination on the studied wood surfaces. By combining wood-surface treatments with GRAS compounds, fungal-area size as predictors and mould grade as response, a partial least squares (PLS) model that makes it possible to predict mould grade on wood surfaces was developed. The PLS model is a key component in the development of a smart grading-systems equipped by e.g. high-speed digital cameras for the early detection of fungal attack on wood surfaces in different applications. However, the measurements based on chemical characterisation should be the next step to take in order significantly to enhance the model and increase the range of robust applications. In the current study, a multivariate model describing the influence of each fungal-covering area on mould grade was presented for the first time.

    Fulltekst (pdf)
    fulltext
  • 31633.
    Myronycheva, Olena
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sehlstedt-Persson, Margot
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Growth of mold and rot fungi on copper-impregnated Scots pine sapwood: Influence of planing depth and inoculation pattern.2018Inngår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 13, nr 4, s. 8787-8801Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The biocidal properties of an industrially used copper-based preservative were evaluated at different planing depths on exposure of pine wood to mold fungi in direct and indirect contamination methods, with simultaneous verification of white rot fungi virulence on wood. The preservative was an aqueous solution of copper carbonate, 2-aminoethanol, and quaternary ammonium compounds. Full cell preservative impregnation efficiency against visual mold fungi growth was tested on sapwood surfaces planed to different depths before impregnation. The virulence of two white rot fungal strains of Trametes versicolor (441 and JPEI) against the dried non-impregnated and impregnated wood samples was also tested. The unplaned surface of impregnated timber was occupied by air-borne contaminants, such as Paecilomyces variottiand Aspergillus niger up to 30%, and, even after impregnation it was necessary to process the surface to avoid micro-fungi settlement. The virulence of the tested rot fungi strains was confirmed by the aggressive degradation of non-impregnated wood with a mass loss of over 40%. Both Trametes sp. strains degraded the preservative-impregnated wood with a mass loss of 3.1% to 4.8%, but degradation by the JPEI strain was more intensive and more dependent on planing depth than the other strain (441).

    Fulltekst (pdf)
    fulltext
  • 31634.
    Myrén, Leo
    KTH, Skolan för teknikvetenskap (SCI), Teknisk mekanik, Farkostteknik och Solidmekanik, Hållfasthetslära.
    Effect of topographical variation for the fatigue of welds2020Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Welding is a common method of joining that is currently used in industry, one example is heavy-duty applications such as cranes, trucks etc.

    The stochastic nature of thewelding process means that several factors are affecting the mechanical properties of the final product. Among these are such measurements as leg length, toe radius, undercut, and toe angle.

    Currently it is hard to evaluate the effect of these parameters in a consistent and time-efficient manner. To that end, this project has been focused on developing a method that utilizes laser scanning in order to get a more comprehensive understanding of how structural integrity is related to the random nature of these parameters.

  • 31635.
    Myrén, Marcus
    et al.
    Blekinge Tekniska Högskola, Institutionen för maskinteknik.
    Olsson, Jörgen
    Blekinge Tekniska Högskola, Institutionen för maskinteknik.
    Modal Analysis of Exhaust System1999Annet (Annet vitenskapelig)
    Abstract [en]

    A modal analysis is performed on an exhaust system for cars. Natural frequencies and mode shapes are correlated between experimental and finite element models. MAC-values are calculated. Theories and guidelines for modal analyses of exhaust systems are discussed.

    Fulltekst (pdf)
    FULLTEXT01
  • 31636.
    Myska, Martin
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    Possibilities with Stirling Engine and High Temperature Thermal Energy Storage in Multi-Energy Carrier System: An analysis of key factors influencing techno-economic perspective of Stirling engine and high-temperature thermal energy storage2021Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Small and medium-scale companies are trying to minimise their carbon footprint and improve their cash flow, renewable installations are increasing all over the Europe and are expected to do so in following years. However, their dependency on the weather cause pressure on matching the production with demand. An option how to challenge this problem is by using energy storage. The aim of this project is to determine techno-economic benefits of Stirling engine and high temperature thermal energy storage for installation in energy user system and identify key factors that affect the operation of such system. In order to determine these factors simulations in Matlab were conducted. The Matlab linear programming tool Optisolve using dual-simplex algorithm was used. The sensitivity analysis was conducted to test the energy system behaviour. Economic evaluation was done calculating discounted savings. From the results, it can be seen the significant benefit of SE-HT-TES installation is the increased self-consumption of the electricity from PV installation. While the self-consumption in cases when there was no energy storage implemented was around 67 % and in one case as low as 50 % with the SE-HT-TES the value has increased up to 100 %. Energy cost savings are 4.7 % of the cost for the original data set and go up to 6.2 % when simulation with load shift was executed. Simulations have also shown that energy customer with predictable energy demand pattern can achieve higher savings with the very same system. It was also confirmed that for users whose private renewable production does not match load potential savings are 30 % higher compared to the system where energy load peak is matching the PV production peak. Simulations also shown that the customers located in areas with higher electricity price volatility can benefit from such system greatly. 

    Fulltekst (pdf)
    Possibilities with Stirling Engine and High Temperature Thermal Energy Storage in Multi-Energy Carrier System
  • 31637.
    Mäehans, Jacqueline
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Teknoekonomisk analys av alternativ elproduktion till svensk kärnkraft2015Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Runt hälften av Sveriges elförsörjning kommer från kärnkraft. De tre verk som finns börjar alla närma sig den beräknade livslängden på 40 år. I dagsläget – dvs. år 2015 – så har tre rektorer redan uppnått deras framtagna livslängder. Dessa är OKG 1, OKG 2 samt Ringhals 2 vars livslängder var 2012, 2014 respektive 2015. Detta projekt har som mål att undersöka om kärnkraften kan ersättas med enbart förnybar elproduktion.

     

    Inledningsvis görs en litteraturstudie där en del fakta tas fram angående dagens existerande kärnkraft; såsom livslängder, byggnadsår, reaktortyper samt elproduktion. Det sistnämnda ligger under de senaste tio åren som mest på 70,3 TWh och minimum har varit 50 TWh.

     

    Därefter undersöks alternativa förnyelsebara tekniker som finns. De som framkom mest troliga att använda i Sverige i dagsläget konstaterades vara vatten-, vind- och solkraft. Kraftvärme är även den ett eventuellt utbyte och nämns kortfattat, men denna uteslöts ur denna analys.

     

    I metoden används en webbaserad beräkningsapplikation framtagen av Elforsk. Genom att anta rimliga värden baserad på fakta ur litteraturstudien – exempelvis som att den totala resursen i Sveriges vattendrag sträcker sig uppemot hela 170 TWh – tas en lämplig ersättning till kärnkraften fram.

     

    Medelvärdet för kärnkraftsproduktionen under de senaste sex åren beräknas till 58,3 TWh. Två varianter – en inklusive och en exklusive solkraft anpassad för villa – visar att det är möjligt att ersätta kärnkraftsproduktionens medelvärde med förnybar el. 

    Fulltekst (pdf)
    fulltext
  • 31638.
    Mählkvist, Simon
    et al.
    Mälardalens universitet, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Ejenstam, Jesper
    Kanthal AB, S-73427 Hallstahammar, Sweden..
    Kyprianidis, Konstantinos
    Mälardalens universitet, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Cost-Sensitive Decision Support for Industrial Batch Processes2023Inngår i: Sensors, E-ISSN 1424-8220, Vol. 23, nr 23, artikkel-id 9464Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work, cost-sensitive decision support was developed. Using Batch Data Analytics (BDA) methods of the batch data structure and feature accommodation, the batch process property and sensor data can be accommodated. The batch data structure organises the batch processes' data, and the feature accommodation approach derives statistics from the time series, consequently aligning the time series with the other features. Three machine learning classifiers were implemented for comparison: Logistic Regression (LR), Random Forest Classifier (RFC), and Support Vector Machine (SVM). It is possible to filter out the low-probability predictions by leveraging the classifiers' probability estimations. Consequently, the decision support has a trade-off between accuracy and coverage. Cost-sensitive learning was used to implement a cost matrix, which further aggregates the accuracy-coverage trade into cost metrics. Also, two scenarios were implemented for accommodating out-of-coverage batches. The batch is discarded in one scenario, and the other is processed. The Random Forest classifier was shown to outperform the other classifiers and, compared to the baseline scenario, had a relative cost of 26%. This synergy of methods provides cost-aware decision support for analysing the intricate workings of a multiprocess batch data system.

  • 31639.
    Mählkvist, Simon
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    Pontus, Netzell
    Pulp mill heat and mass balance model: Exploring the benefits and possibilities of process modelling as an applied method in a case study2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis focused on the modelling of a pulping process. The purpose was to see if an accurate model can be crated based on relatively simple premises and if the errors can be identified or analysed. To realise this, the authors conducted a literature study to identify the current state of the art regarding the chemical pulping process. In addition, flow charts and sample data from a case study were examined. Based on the literature review and case study, model assumptions were derived. The model is divided into sixteen components. Where mixing occurs, lumped conditions are assumed. The model has five validation points, four of which are temperatures and a mass flowrate. These are shown as deviations from the measured values. In conclusions, it was the model could produce stable results over a narrow time frame. More so if the transition period at the start of the simulation is overlooked. Several new model assumptions are presented with the purpose to increase accuracy e.g. account for the components ability to store mass.

    Fulltekst (pdf)
    fulltext
  • 31640.
    Mähönen, Joonas
    et al.
    BRP Finland Oy, Finland.
    Lintzén, Nina
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Casselgren, Johan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Portable bevameter for measuring snow properties in field2021Inngår i: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 182, artikkel-id 103195Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mechanical properties of snow related to snowmobiles or similar lightweight tracked vehicles aren't widely researched today and it is difficult to find data. One challenge is that snow properties constantly are changing due to aging, climate conditions and location. Also the measuring procedure is difficult since aged snow often contains layers with various densities and hardness. Soil is to some extent similar to snow, in the context that both are granular materials. The bevameter is a popular device for measuring soil properties, however this device needs to be scaled in order to meet criteria of target for research, i.e. in this case snowmobiles. In this paper a new type of portable bevameter is presented, which is designed and built for measuring snow properties in the field. Results from initial tests are also presented. The aim with the bevameter is to measure snow properties which can be used to simulate the interaction between a snowmobile and soft snow. The designed bevameter can be towed with one snowmobile to the field to execute measurements. One full set of test results is introduced and parameters for simulations are extracted from the result data. The parameters from the data were usable but the quality of the measurements can be improved. One problem with the data collected was noise, which was caused by the interaction between the mechanical parts and the low mass of the bevameter. Furthermore, the usability can be improved by reducing cables which can be hard and fragile during cold weather and by replacing the laser distance-sensor with a string wire potentiometer which isn't sensitive to snow dropping in the measurement area. With some improvements the constructed bevameter is a very useful tool which can be used for field measurements to determine snow properties for snowmobile-size vehicle simulations.

  • 31641.
    Mäkelä, Petri
    et al.
    STFI Packforsk AB.
    Östlund, Sören
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Cohesive crack modelling of paper materials2007Inngår i: Proceedings of the 2007 International Paper Physics Conference, 2007, s. 357-364Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    When a notched structure is subjected to sufficiently large tensile loading, it generally exhibits damage evolution in the crack tip region. In paper materials, this damage evolution may reach considerable sizes before ultimate collapse of the structure occurs. Gradual crack growth, characterized by large-scale damage evolution ahead of the crack tip prior to ultimate failure, makes the determination of the initiation of crack growth ill-conditioned and causes the loading in the structure to increase non-proportionally. The applicability of fracture mechanics models that neglect damage evolution, such as classical non-linear fracture mechanics models, therefore becomes questionable for paper materials. The aim of this work was to develop an anisotropic elasticplastic cohesive crack model, i.e. a fracture mechanics model that is capable of accurately describing the anisotropic non-linear constitutive behaviour and the damage behaviour of paper materials. Furthermore, the aim was to use the developed model for studying whether the crack tip state can be characterised by one parameter, as in classical non-linear fracture mechanics models, although large-scale damage evolves. An orthotropic incremental elastic-plastic softening cohesive crack model was formulated. The material parameters of the cohesive crack model were determined for one grade of commercial paper, solely by tensile testing. Short tensile test pieces, allowing for stable post-peak stress behaviour during tensile testing, were used to determine the damage material parameters. The developed cohesive crack model is selfcontained in fracture mechanics applications, i.e. no testing on notched structures was required for calibrating the fracture criterion. The accuracy of the cohesive crack model was investigated by comparing model predictions with experimental data from ordinary tensile tests in different material directions and from tensile testing of notched test pieces with different crack lengths. The calibrated cohesive crack model was shown to predict constitutive behaviour and ultimate failure in excellent agreement with the experiments. The cohesive crack model was further used for examining the crack tip region in more detail. It was demonstrated that the J-integral may accurately characterise the stress and deformation state in the vicinity of the crack tip, although large-scale damage evolves in the crack tip region.

  • 31642.
    Mäki, Jonatan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Energieffektivisering av "kontorslimpan": Energianalys med förslag till energieffektiviserande åtgärder2018Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Sektorn bostäder och service står för nära 40 % av Sveriges totala energianvändning. Inom denna sektor står hushåll och lokaler för ungefär 90 % av energianvändningen. Det finns stora möjligheter till besparingar i byggnader genom energieffektivisering.Syftet med projektet är att ta fram förslag på åtgärder som på ett kostnadseffektivt sätt kan minska byggnadens energianvändning.Energiberäkningsprogrammet BV2 har använts för att bygga upp en modell av byggnaden. Den simulerade modellens energianvändning jämförs sedan mot uppmätta värden på energianvändningen för att se hur väl modellen stämmer överens med verkligheten.När dessa stämmer överens övergår arbetet till att undersöka olika energieffektiviseringsåtgärder. Simuleringar utförs för åtgärder som installation av värmeväxlare, tilläggsisolering av vindbjälklag och byte av fönster etc.Av de åtgärder som har undersökts har installation av roterande värmeväxlare den kortaste återbetalningstiden på ungefär 3 år, vätskekopplad värmeväxlare hamnar aningen högre med en återbetalningstid på 3,5 - 4 år. Tilläggsisolering av vindbjälklag har en återbetalningstid på runt 5,5 - 6,5 år vid en tjocklek på 350 mm. Denna åtgärd är, efter installation av värmeväxlare, den mest lönsamma och är även relativt enkel att utföra.Utifrån de simulerade åtgärderna har ett åtgärdspaket tagits fram och undersökts med Beloks internräntemetod. Resultatet för hela åtgärdspaketet ger en internränta på 18,7 % och en återbetalningstid på 5 år. Detta överstiger avkastningskravet på 7 % med god marginal.

    Fulltekst (pdf)
    Energieffektivisering av "kontorslimpan"
  • 31643. Mäki, Rikard
    Apparatus for measurement of friction surface temperature in a wet clutch2001Inngår i: Tribology 2001 : scientific achievements, industrial applications, future challenges: plenary and session key papers from the 2nd World Tribology Congress, Vienna, Austria, 3 - 7 September / [ed] Friedrich Franek, Wien: ÖTG , 2001Konferansepaper (Fagfellevurdert)
  • 31644. Mäki, Rikard
    Wet clutch tribology: friction characteristics in all-wheel drive differentials2003Inngår i: Tribologia : Finnish Journal of Tribology, ISSN 0780-2285, Vol. 22, nr 3, s. 5-16Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In recent past several electronically controlled automotive transmission systems, where wet clutches are used as intelligent differentials, have emerged on the market. These applications generally impose high stresses on the transmission fluids. The fluids must retain the desired frictional characteristics at different torque levels during its lifetime in an environment where the ambient and system temperatures vary in a wide temperature range. This paper deals with friction characteristics of transmission fluids for wet clutches in all-wheel drive systems, and summarizes a recent licentiate thesis on the subject. The all-wheel drive system, featuring a wet multi-plate clutch with a sintered bronze based friction material, is described. Test equipment designed in order to determine the frictional characteristics of transmission fluids are described. This equipment can also be used to measure the actual temperature experienced by the fluid in the contact zone using an infrared temperature measurement method. Results show the influence of several operating parameters on the frictional behaviour of the clutch. Temperature is shown to have significant influence on the friction characteristics of transmission fluids. The friction decreases with increasing temperature, and it is therefore necessary to measure the correct temperature in the clutch to obtain realistic values of friction. The friction-velocity relationship is a good indicator of the fluid's ability to suppress friction induced vibrations. It is, however, important to measure the friction-velocity relationship at constant temperature, or compensate the relationship accordingly. The influence of clutch disc pressure on friction is quite moderate, as compared to the influence of temperature and sliding velocity. The influence of different oil additives on friction has also been investigated. These additives have considerable influence on friction, and this must be considered when formulating new transmission fluids.

  • 31645. Mäki, Rikard
    Wet clutch tribology: friction characteristics in all-wheel drive differentials2003Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    In recent past, several electronically controlled automotive transmission systems, where wet clutches are used as intelligent differentials, have emerged on the market. These applications generally impose high stresses on the transmission fluids. The fluids must retain the desired frictional characteristics at different torque levels during its lifetime in an environment where the ambient and system temperatures vary in a wide temperature range. This thesis is focused on transmission fluids for wet clutches in all-wheel drive systems. The all-wheel drive system, featuring a wet multi-plate clutch with a sintered bronze based friction material, is described and compared to other systems on the market. A comprehensive literature review section where the state-of-art in this field is presented gives an insight to many of the problems commonly experienced in this type of application. Different methods to investigate the function of wet clutch transmission fluids are also presented. Test equipments designed during this thesis work in order to determine the frictional characteristics of transmission fluids are described. These equipments can also be used to measure the actual temperature experienced by the fluid in the contact zone using an infrared temperature measurement method. Results show the influence of several operating parameters on the frictional behavior of the clutch. Temperature is shown to have significant influence on the friction characteristics of transmission fluids. The friction decreases with increasing temperature, and it is therefore necessary to measure the correct temperature in the clutch to obtain realistic measurements of friction. The friction-velocity relationship is a good indicator of the fluids ability to suppress friction induced vibrations. It is, however, important to measure the friction-velocity relationship at constant temperature, or compensate the relationship accordingly. The influence of clutch disc pressure on friction is quite moderate, as compared to the influence of temperature and sliding velocity. The influence of different oil additives on friction has also been investigated. These additives have considerable influence on friction, and this must be considered when formulating new transmission fluids.

  • 31646. Mäki, Rikard
    Wet clutch tribology: friction characteristics in limited slip differentials2005Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    In recent years, electronically controlled automotive transmission systems, where wet clutches are used as intelligent differentials, have appeared in the market. These applications impose great demands on the transmission fluids and friction materials used as well as on controllability and vibration preventive (anti-shudder) properties of the clutch systems. This thesis focuses on transmission fluids used in wet clutches in all- wheel drive systems. The investigated all-wheel drive system, featuring a wet multi-plate clutch with a sintered brass based friction material, is described. A comprehensive literature review section outlines the state-of-art in this field and gives an insight into many of the problems commonly experienced in this type of application. Different methods used to investigate the function of wet clutch transmission fluids are also presented. Test equipment designed during this thesis work in order to determine the frictional characteristics of transmission fluids is described. This equipment measures friction torque, normal load, oil temperatures and the actual temperature experienced by the fluid in the contact zone. Base oil type and viscosity have been found not to significantly influence friction characteristics of a wet-plate clutch , indicating that the torque is primarily transmitted by asperity contacts rather than fluid films. Oil additives, on the other hand, have a considerable influence on friction, again leading to the conclusion that tribolayers on contacting asperities rather than fluid films govern friction. From these observations it can be concluded that the lubrication regime under the conditions studied are boundary lubrication, moving into mixed lubrication at high velocities and low temperatures. Results show the influence of several operating parameters on the frictional behavior of the clutch. Temperature is shown to have significant influence on the friction of transmission fluids which decrease with increasing temperature. It is therefore necessary to measure the true temperatures in the clutch contact in order to obtain realistic measurements of friction. A method which excludes the influence of temperature on measured friction data have been developed and verified. The influence of clutch disc pressure on friction is quite moderate compared to the influence of temperature and sliding velocity. The influence of velocity on friction is governed by the transmission fluid and friction material used in the clutch. The friction-velocity relationship is a good indicator of the fluid’s ability to suppress friction induced vibrations. It is, however, important to measure the friction-velocity relationship at constant temperature, or to compensate the relationship for temperature effects. A successful method to develop transmission fluids has been developed. Formulated fluids allow good anti-shudder properties to be combined with good lubrication performance for other machine elements present in the transmission. Interactions between different additives must be considered which can, in many cases, completely alter the friction characteristics since additives compete for the same adsorption surface. Extreme pressure additives have been found to be particularly troublesome when used in combination with other additives as far as their ability to maintain good anti-shudder properties is concerned. Based on the knowledge of clutch performance obtained from the research presented in this thesis, a model to predict transmitted clutch torque has been developed. This accurately determines the transferred torque from the current operating conditions and the thermal history of the clutch. It can be concluded that thermal effects have a significant influence on the torque transferred by the clutch, and it is therefore necessary to have a thermal model of the clutch combined with a temperature dependant boundary friction model based on empirical friction data for the friction material/transmission fluid combination of interest.

    Fulltekst (pdf)
    FULLTEXT01
  • 31647.
    Mäki, Rikard
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Ganemi, B.
    Statoil Lubricants, Stockholm.
    Flores, R.T.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Olsson, R.
    Haldex Traction Systems AB.
    Wet clutch transmission fluid for AWD differentials: influence of lubricant additives on friction characteristics2006Inngår i: Automotive and industrial lubrication: 15th International Colloquium Tribology, January 17 - 19, 2006 ; [book of synopses 2006] / [ed] Wilfried J. Bartz, Ostfildern: Techn. Akad. Esslingen , 2006, s. 35-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A study on the influence of base oils on friction properties was carried out. The effects of additive interactions must be considered but were hard to predict. This was most notable with EP additives that were hard to combine with other additives without compromising the anti-shudder properties of the clutch. The developed fluid showed that it is feasible to combine anti-shudder properties and hypoid gear lubrication abilities in one fluid. Good anti-shudder properties were realized despite high concentrations of EP additives. This is an abstract of a paper presented at the 15th International Colloquium Tribology-Automotive and Industrial Lubrication (Ostfildern, Germany 1/17-19/2006).

  • 31648. Mäki, Rikard
    et al.
    Ganemi, B.
    Statoil Lubricants R&D.
    Olsson, R.
    Haldex Traction Systems AB.
    Wet clutch transmission fluid, development method2002Inngår i: 10th Nordic Symposium on Tribology: NORDTRIB 2000 : Hotel Foresta and KTH, Stockholm, Sweden, June 9-12, 2002, Stockholm: Kungl. Tekniska Högskolan , 2002, s. 144-Konferansepaper (Annet vitenskapelig)
  • 31649. Mäki, Rikard
    et al.
    Ganemi, B.
    Statoil Lubricants, Nynäshamn.
    Olsson, R.
    Haldex Traction Systems AB.
    Wet clutch transmission fluid for AWD differentials: base fluid influence on friction characteristics2004Inngår i: Tribology and lubrication engineering: 14th International Colloquium Tribology, January 13 - 15, 2004 / [ed] Wilfried J. Bartz, Ostfildern: Techn. Akad. Esslingen , 2004, s. 399-404Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The influence of base fluids on the anti-shudder properties of transmission fluids for wet clutches in all-wheel drive systems was studied. The all-wheel drive system, featuring a wet multi-plate clutch with a sintered brass base friction material, was described. Five different fluids (Fluid C = semi-synthetic, Fluid A and E = synthetic based fluids combined with the additive package from Fluid C, Fluid B and D = mineral based fluids combined with the additive package from fluid C) were used. Fluids A and B were low viscosity fluids while Fluids D and E were high viscosity fluid. The low viscosity base fluids presented a higher temperature dependence of the dynamic friction, μ50, compared to high viscosity fluids. These low viscosity fluids had better anti-shudder properties compared to the high viscosity fluids, especially at lower temperatures. The friction characteristics were mainly additive dependant, since large differences in the friction parameters could be observed from tests run at temperatures corresponding to a given viscosity. Synthetic and mineral base fluids showed similar behavior while the semi-synthetic commercial fluid presented better performance in some areas, implying that the additive package lose some performance when placed in a different base fluid than the originally intended. This is an abstract of a paper presented at the Technische Akademie Esslingen 14th International Colloquium Tribology (Stuttgart/Ostfildern, Germany 1/13-15/2004).

  • 31650. Mäki, Rikard
    et al.
    Ganemi, Bager
    Svenska Statoil AB.
    Höglund, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Olsson, Richard
    Haldex Traction Systems AB.
    Wet clutch transmission fluid for AWD differentials: influence of lubricant additives on friction characteristics2007Inngår i: Lubrication Science, ISSN 0954-0075, E-ISSN 1557-6833, Vol. 19, nr 2, s. 87-99Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In recent years, several electronically controllable automotive transmission systems using wet clutches as intelligent differentials have emerged on the market. These applications place great demands on the anti-shudder properties of the transmission fluids used. The aims of this study were (i) to investigate the influence of different additives on the friction characteristics of a transmission fluid for all-wheel drive systems featuring wet multi-plate clutch with a sintered brass-based friction material and, based on this knowledge, (ii) to formulate a new transmission fluid with the desired frictional properties. In addition to excellent anti-shudder properties, the new fluid was required to lubricate hypoid gears under high load. To meet this requirement, it is necessary to add significant amounts of extreme pressure additives to the base oil, which are known to have an unfavourable influence on anti-shudder properties, necessitating the adoption of novel additive technologies. The additives studied include anti-wear additives, friction modifiers, corrosion inhibitors, detergents, antioxidants and extreme pressure additives. This paper shows how different additives affect friction in different ways, and that the interactions between the different additives are important to consider. It was concluded that it is feasible to combine good anti-shudder properties for wet clutches with good lubrication of hypoid gears.

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