Torsional vibration absorbers in heavy-duty truck powertrains

The heavy-duty vehicle manufacturers face large challenges when it comes to reducing CO2 emissions from vehicles. The ongoing development of more efficient combustion engines leads to an increase in torsional vibrations. Experience within the industry indicates that the conventional single mass flywheel (SMF) and clutch will not be enough to protect the gearbox and rear driveline from engine induced vibrations in the future; more advanced technology will be needed.The work presented in this thesis focuses on simulation and analysis of torsional vibration absorbers for heavy-duty truck applications. Different multiple-mass flywheels are analysed, including dual mass flywheels (DMFs), power split vibration absorbers (PSVAs) and DMFs combined with tuned vibration absorbers (TVAs). DMFs have been used in smaller vehicles for many years, but the use in heavy-duty commercial applications is to date very limited. The other two vibration absorbers studied in this work have not yet been industrialised.The vibrations absorbers are analysed by means of simulations. Methodologies for efficient simulations in time- and frequency-domain have been developed and are presented in the thesis. The frequency-domain methods used include the harmonic response and a harmonic balance method, combined with an arc-length continuation scheme. For models with many gap-activated springs, a time-domain approach is proposed, where the dynamics problem is reformulated as a linear complementary problem (LCP).A detailed DMF model, including internal parts, friction and clearances, is presented for time-domain studies requiring high accuracy. The model is correlated based on test rig measurements.The torsional vibrations in typical heavy-duty truck powertrains with the different multiple-mass flywheels are simulated in a large engine load and speed range. The results are analysed and compared to corresponding conventional powertrains. It is evaluated how different design parameters affect the torsional vibrations and the feasibility of the concepts for heavy-duty use is studied. The simulations show that the torsional vibration amplitudes are generally significantly lower with a DMF than with an SMF, but under some conditions significant resonance excitation can occur. The PSVA and DMF equipped with a TVA can reduce vibrations further than a corresponding DMF within limited speed ranges, but lead to higher vibration amplitudes outside these ranges

Integrated Dynamic Aquaculture and Wastewater Treatment Modelling for Recirculating Aquaculture Systems

Recirculating aquaculture systems (RAS) in land based fish tanks, where the fish tank effluent is biologically treated and then recirculated back to the fish tanks, offers a possibility for large scale ecologically sustainable fish production. In order to fully exploit the advantages of RAS, however, the water exchange should be as small as possible. This implies strong demands on the water treatment, e.g. the maintenance of an efficient nitrification, denitrification and organic removal. Because of the RAS complexity, though, dynamic simulations are required to analyze and optimize a plant with respect to effluent water quality, production and robustness. Here, we present a framework for integrated dynamic aquaculture and wastewater treatment modelling. It provides means to analyze, predict and explain RAS performance. Using this framework we demonstrate how a new and improved RAS configurations is identified

Dual mass flywheels in truck powertrains, Modelling, simulations and validation

The heavy-duty vehicle manufacturers face large challenges when it comes to reducing CO2 emissions from vehicles. The on-going development of more efficient combustion engines leads to an increase in torsional vibrations. In the future, the conventional flywheel and clutch will probably not be enough to protect the gearbox and rear driveline from engine induced vibrations. More advanced technology will be needed.Dual mass flywheels (DMFs) have been used in smaller vehicles for many years and have shown to reduce the torsional vibrations transmitted to the gearbox. The use in heavy-duty commercial applications is to date very limited.The work presented in this thesis focuses on DMFs for heavy-duty applications. It comprises modelling, measurements, correlation, development of numerical algorithms and complete powertrain simulations.Two different DMF simulation models are used. The first one is a piecewise linear model, without the internal DMF parts explicitly modelled. It is used together with the harmonic balance method to evaluate resonances. The simulated results show that with piecewise linear DMF design, sub-harmonic resonance excitation can occur in operating speed range.The second model includes the DMF internal parts. A simulation method where the dynamics problem is reformulated as a linear complementary problem (LCP) is proposed. The model is correlated based on test rig measurements on a DMF for heavy-duty applications. It is shown that the general DMF behaviour, as observed in the measurements, can be reproduced in the simulations for the speed and torque ranges studied.The torsional vibrations in a heavy-duty truck powertrain with a single mass flywheel model and with the second DMF model are evaluated with simulations. The effects on resonance modes and frequencies when changing different powertrain parameters are presented. The simulations show that the vibration amplitudes are generally lower with a DMF. Resonance excitation can occur in operating speed range with the DMF and the DMF and clutch properties need to be adapted to the powertrain in order to obtain good vibration isolation in the complete operating speed and torque range

Vibration dynamics in non-linear dual mass flywheels for heavy-duty trucks

A non-linear model for simulations of a dual mass flywheel (DMF) for heavy-duty applications is proposed. The model includes internal clearances and friction. LuGre friction model is used, which depends on normal force, relative velocity between the two surfaces and an internal deflection variable. Measurements on the DMF are performed in a test rig and the test rig properties are analysed. The correlation shows that the general behaviour of the DMF is reproduced by the proposed simulation model. The viscous part of the friction is dominant for the analysed cases with zero mean torque, and a conventional Coulomb friction model would not suffice for this application. Near resonances, the model also shows a high sensitivity to internal clearances and spring stiffness. This indicates that correlation could be improved further if the static stiffness was measured with good accuracy for the relevant range of deflection angles

Genetic Risk Factors in Lupus Nephritis and IgA Nephropathy - No Support of an Overlap

Background: IgA nephropathy (IgAN) and nephritis in Systemic Lupus Erythematosus (SLE) are two common forms of glomerulonephritis in which genetic findings are of importance for disease development. We have recently reported an association of IgAN with variants of TGFB1. In several autoimmune diseases, particularly in SLE, IRF5, STAT4 genes and TRAF1-C5 locus have been shown to be important candidate genes. The aim of this study was to compare genetic variants from the TGFB1, IRF5, STAT4 genes and TRAF1-C5 locus with susceptibility to IgAN and lupus nephritis in two Swedish cohorts. Patients and Methods: We genotyped 13 single nucleotide polymorphisms (SNPs) in four genetic loci in 1252 DNA samples from patients with biopsy proven IgAN or with SLE (with and without nephritis) and healthy age-and sex-matched controls from the same population in Sweden. Results: Genotype and allelic frequencies for SNPs from selected genes did not differ significantly between lupus nephritis patients and SLE patients without nephritis. In addition, haplotype analysis for seven selected SNPs did not reveal a difference for the SLE patient groups with and without nephritis. Moreover, none of these SPNs showed a significant difference between IgAN patients and healthy controls. IRF5 and STAT4 variants remained significantly different between SLE cases and healthy controls. In addition, the data did not show an association of TRAF1-C5 polymorphism with susceptibility to SLE in this Swedish population. Conclusion: Our data do not support an overlap in genetic susceptibility between patients with IgAN or SLE and reveal no specific importance of SLE associated SNPs for the presence of lupus nephritis.Original Publication: Mai Tuyet Vuong, Iva Gunnarsson, Sigrid Lundberg, Elisabet Svenungsson, Lars Wramner, Anders Fernström, Ann-Christine Syvanen, Lieu Thi Do, Stefan H. Jacobson and Leonid Padyukov, Genetic Risk Factors in Lupus Nephritis and IgA Nephropathy - No Support of an Overlap, 2010, PLOS ONE, (5), 5. http://dx.doi.org/10.1371/journal.pone.0010559 Licensee: Public Library of Science (PLoS) http://www.plos.org/</p

Genetic variation in the transforming growth factor-β1 gene is associated with susceptibility to IgA nephropathy

Background. There is growing evidence of genetic risk for susceptibility to IgA nephropathy. Among several candidate genes related to immunological regulation in renal tissue, TGFB1 is known to be a contributor to proliferation and the development of fibrosis

Torsional vibrations in truck powertrains with dual mass flywheel having piecewise linear stiffness

The vehicle industry faces big challenges when it comes to reducing the emissions of heavy vehicles. In order to cope with the increasing demand for efficient, low emission vehicles, the trend within the industry is to down-size and down-speed the engines. These measures lead to higher torsional vibrations in the powertrain and therefore there is also an increasing need for efficient reduction of torsional vibrations. One way to reduce the vibration is to use a dual mass flywheel. A dual mass flywheel consists of two flywheels connected by a torsional spring package.\ua0 The spring package should have low stiffness but must also cope with very high torques. Therefore the dual mass flywheels are often designed so that they have a piecewise linear relationship between torque and wind-up angle. A full powertrain model has been used with realistic engine load in order to evaluate how the piecewise linear design affects the vibrations in the powertrain. Simulations have been performed in frequency domain and time domain and evaluation is done both with respect to mode shapes and frequencies and computed steady-state vibration amplitudes. In the linear region, there is a frequency shift for a problematic resonance mode that leads to significant decrease in vibration amplitude at low engine speeds. In non-linear regions, a resonance mode corresponding to half the main exciting frequency from the engine can be excited, leading to high vibration amplitudes. The frequency of this mode and the extent to which it is excited depends on the engine torque and highest amplitudes are not always obtained at the highest load

ALLMÄN FISKEVÅRDSAVGIFT I SVERIGE : Utredningsrapport om utformningen av en allmän fiskevårdavgift i Sverige

Utredningens uppdrag har varit att utforma ett detaljerat förslag till allmän fiskevårdsavgift. Utredningen konstaterar ett stort och ökande behov av fiskevård som inte har tillgodosetts på grund av medelsbrist. Det föreslås att en allmän fiskevårdsavgift införs och att avgiftsmedlen används för att finansiera angelägna fiskevårdsinsatser. Den allmänna fiskevårdsavgiften bör i princip erläggas av alla fiskande över 18 år. Den bör sättas så att medlen ger ett substantiellt bidrag till fiskevården samtidigt som ingen av ekonomiska skäl hindras från att fiska. Avgiften bör vara differentierad enligt följande: handredskapsfiske, år 100 kr handredskapsfiske, vecka 40 kr husbehovsfiske, år 250 kr yrkesfiske, år 500 kr Enligt förslaget bör den allmänna fiskevårdsavgiften hanteras av Fiskeriverket men beslut om avgiftsmedlens användning bör fattas av ett särskilt råd med fem ledamöter. Dessa föreslås representera Sveriges sportfiske- och fiskevårdsförbund, Sveriges fiskevattenägareförbund, Sveriges fiskares riksförbund, allmänintresset samt Fiskeriverket. Avgiftsmedlen föreslås i första hand användas för bidrag till bildande av fiskevårdsområden, fiskevårdsåtgärder inklusive utsättning av fisk, fisketillsyn och utveckling av fiskevården. De medel som den allmänna fiskevårdsavgiften inbringar bör förvaltas av Fiskeriverket och enbart användas för fiskevård och hantering av avgiftssystemet. Inbetalningen av avgiften bör i första hand ske via postgirot. Färdigtryckta giroblanketter bör ges en vid spridning. Avgiften bör också kunna inbetalas kontant till försäljare av fiskekort, turistbyråer m.fl. Av bl.a. kostnadsskäl bedöms det inte vara motiverat att upprätta ett särskilt register över de personer som erlagt avgift. Kontrollen av att allmän fiskevårdsavgift erlagts bör ske inom ramen för den ordinarie fisketillsynen. Denna föreslås dock förstärkas via medel ur den allmänna fiskevårdsavgiften

Dual-mass flywheels with tuned vibration absorbers for application in heavy-duty truck powertrains

As the heavy-duty combustion engine development goes towards lower rotational speeds and higher cylinder pressures, the torsional vibrations increase. There is therefore a need to identify and study new types of vibration absorbers that can reduce the level of torsional vibrations transmitted from the engine to the gearbox. In this work, the concept of a dual-mass flywheel combined with a tuned vibration absorber is analysed. The tuned vibration absorber efficiently reduces the vibration amplitudes for engine load frequencies near the tuning frequency, but it also introduces an additional resonance into the system. By placing the tuned vibration absorber on an intermediate flange between the two dual-mass flywheels, the introduced resonance frequency will be lower than the tuning frequency and a resonance in operating engine speed range can be avoided. Numerical simulations are used to show how the torsional vibration amplitudes in a heavy-duty truck powertrain are affected by the tuned vibration absorber and how the different parameters of the tuned vibration absorber and the dual-mass flywheel affect the torsional vibrations and the resonance frequencies

Synkronisering och desynkronisering - Hur människans hjärna bearbetar lätt beröring

Hos människan finns det två typer av sensoriska nerver som på huden registrerar lätt beröring. Dessa två kallas Aβ- och CT-afferenter. De registrerar när något rör vid huden och skickar då elektriska impulser upp till hjärnan, vilket leder till känslan av beröring. Aβ-afferenter leder elektriska impulser snabbt och har funktioner såsom att avgöra objekts lokalisering och rörelse över huden. CT-afferenter leder elektriska impulser långsamt och har endast receptorer belägna i behårad hud. Deras funktion är ännu inte helt känd, men det finns forskning som indikerar att de är viktiga för hur behaglig vi upplever att en beröring är. Man vet heller inte vart i hjärnan de impulser de skickar till slut hamnar. Detta har lett till att mycket forskning har gjorts på detta, för att få en större förståelse för hur behaglig beröring bearbetas i hjärnan och i slutändan hur den skulle kunna påverka vårt beteende. En av de metoder som har använts för att studera hur lätt beröring bearbetas i hjärnan är elektroencefalografi, förkortat EEG. Den fungerar genom att man placerar elektroder på huvudet hos en försöksperson. Dessa elektroder kan registrera de spänningsskillnader som uppstår när nervcellerna i hjärnan skickar elektriska impulser mellan varandra. Detta kan dels ses som positiva eller vågor eller som en synkronisering eller desynkronisering av nervcellernas impulser, vilket innebär att impulser vid vissa frekvenser ökar eller minskar. Synkroniseringen anses stå för en del av hjärnan som är inaktiv, medan desynkronisering anses stå för en del av hjärnan som aktivt bearbetar information. Vid en tidigare EEG-studie på lätt beröring såg man två positiva vågor, en tidig och en sen. Tidpunkten för den första var då man förväntar sig att impulser från Aβ-afferenter når hjärnan, och tidpunkten för den andra var då man förväntar sig att impulser från CT när hjärnan. Denna sena våg såg man däremot inte när man gjorde ett liknande experiment med Magnetoencefalografi (förkortat MEG, en metod som registrerar magnetfält som uppstår av de ovan nämnda spänningsskillnaderna i hjärnan). Syftet med denna studie har därmed varit att med EEG vidare undersöka aktivitet som uppstår i hjärnan vid lätt beröring, med en fokus på eventuell sen aktivitet. Detta för att få en större förståelse för hjärnans bearbetning av lätt och behaglig beröring. En väsentlig skillnad från tidigare den EEG-studien är att vi har använt oss av en EEG-inspelning med 128 elektroder, istället för 64. Detta för att få en högre precision för var i hjärnan vi ser aktivitet och för att eventuellt se något man inte tidigare kunnat se. Den typ av aktivitet vi har letat efter i detta arbete är synkronisering och desynkronisering av nervcellernas impulser. Det frekvensintervall vi främst tittat på kallas beta, vilket innebär impulser mellan 15 och 30 Hz. EEG spelades in på 14 försökspersoner, samtidigt som de stimulerades med en mjuk borste på överarmen 200 gånger, på ett sådant sätt som definierats som optimalt för att aktivera CT-afferenter. Med hjälp av medelvärdet för de 200 stimuleringarna utfördes så kallad tids-frekvensanalys. Med denna metod räknade man ut synkronisering och desynkronisering av nervcellsimpulser efter stimuleringstillfället. Det mest framstående resultat vi fick var en desynkronisering i mittlinjen av hjärnan efter 1,2 sekunder. Eftersom vi såg en desynkronisering kan vi anta att detta representerar en del av hjärnan som aktivt bearbetar information. Den sena tidpunkten för denna aktivitet stämde överens med då man kan förvänta sig att impulser från CT-afferenter når hjärnan. Man har tidigare sett aktivitet i mittlinjen när man har studerat lätt beröring med EEG och MEG, men inte i form av en desynkronisering vid denna sena tidpunkt. Därmed anser vi att vi har hittat en ny möjlig representation av hjärnans bearbetning av lätt och behaglig beröring. Vi tror att den sena aktiviteten beror på både impulser från CT- och Aβ-afferenter, vilket stämmer överens med tidigare slutsatser om att båda typerna av afferenter är viktiga för upplevelsen av beröring som behaglig. Vidare forskning krävs för att utreda betydelsen av den sena desynkroniseringen, och den fortsatta planen inom forskningsgruppen är att räkna ut vilka anatomiska strukturer i hjärnan som gett upphov till denna aktivitet.The aim of this study was to investigate human brain activity following gentle touch. Two types of afferents register gentle touch on the hairy skin in humans: myelinated Aβ-, and the unmyelinated CT-afferents. Aβ have mostly qualities of discriminative processing of touch, whereas CT-afferents have been suggested to be important for pleasant touch. Since the cortical projections of the CT-afferents are not known, there is a reason to investigate them further, in order to gain more knowledge of pleasant touch, the brain mechanisms that are involved, and ultimately to understand the way this might affect behavior. With a difference in conduction velocity, there is a potential for seeing two waves of activity in the brain, with the first one being due to Aβ- and the second to CT-input. This was illustrated in an earlier EEG study. This late activity was however not detected in a following MEG study. Here, we wanted to further investigate this with EEG experiments using a 128-electrode cap, which provides a higher spatial resolution than the previous EEG study. We found a late event-related reduction of oscillations in the 15-30 Hz beta range (event-related desynchronization, ERD). This was not seen in previous studies, which might be explained by the higher spatial resolution of these recordings. Since this late activity both in time and localization might be explained by the late CT-input, this could be a reflection of the cortical processing of CT-afferents that has not been presented before. In order to conclude what brain area was responsible for this activity, source localization analysis should be performed