| 61. |
- Albinsson, Anton, 1989, et al.
(författare)
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Identification of tyre characteristics using active force excitation
- 2016
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Ingår i: The Dynamics of Vehicles on Roads and Tracks - Proceedings of the 24th Symposium of the International Association for Vehicle System Dynamics, IAVSD 2015. - : CRC Press. - 9781138028852 ; , s. 501-510
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Konferensbidrag (refereegranskat)abstract
- Knowledge of the maximum tyre-road friction coefficient can improve active safety systems by defining actuator boundaries and adaptable intervention thresholds. Estimation of the coefficient of friction based on tyre response measurements requires large level of force excitation. Under normal driving conditions, manoeuvres with large tyre utilizations are rare. This study investigates a method where wheel torques with opposite signs are applied to the front and rear axle simultaneously. This procedure allows for an intervention with large tyre excitations without disturbing the motion of the vehicle. The intervention is evaluated in simulations and experiments. Further, a method is proposed which does not require measurement of the vehicle longitudinal velocity. The results show that it is possible to estimate the current friction coefficient with the proposed method, although the assumption made in the proposed method makes the friction estimate sensitive to measurement noise on the wheel speed signal.
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| 62. |
- Almgren, Mats, et al.
(författare)
-
Cryotransmission electron microscopy of thin vitrified samples.
- 1996
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Ingår i: Current Opinion in Colloid & Interface Science. - 1359-0294 .- 1879-0399. ; 1:2, s. 270-278
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Tidskriftsartikel (refereegranskat)abstract
- During the past few years cryotransmission electron microscopy (EM) of vitrified thin samples has gained acceptance as a standard method in the arsenal of the colloid and interface scientist. The seemingly direct visualization of fluid colloidal structures during the use of cryotransmission EM is both convincing and reliable to the scientist who nowadays has an increasing awareness of the limitations and pitfalls of instrumentation. Notable recent observations include branched threadlike micelles, faceted particles (cubosomes) of a dispersed cubic phase and transitions of certain structures from globular micelles via bilayers to reversed structures. These transitions may be caused by changes of compos ition, temperature, pH, or salt concentration.
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| 63. |
- Alves, C. A., et al.
(författare)
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Physical and chemical properties of non-exhaust particles generated from wear between pavements and tyres
- 2020
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Ingår i: Atmospheric Environment. - : Elsevier Ltd. - 1352-2310 .- 1873-2844. ; 224
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Tidskriftsartikel (refereegranskat)abstract
- A road simulator was used to generate wear particles from the interaction between two tyre brands and a composite pavement. Particle size distributions were monitored using a scanning mobility particle sizer and an aerosol particle sizer. Continuous measurements of particle mass concentrations were also made. Collection of inhalable particles (PM10) was conducted using a high-volume sampler equipped with quartz filters, which were then analysed for organic and elemental carbon, organic constituents and elemental composition. Tyre fragments chopped into tiny chips were also subjected to detailed organic and elemental speciation. The number concentration was dominated by particles <0.5 μm, whereas most of the mass was found in particles >0.5 μm. The emission factor from wear between pavements and tyres was of the order of 2 mg km−1 veh−1. Organic carbon represented about 10% of the PM10 mass, encompassing multiple aliphatic compounds (n-alkanes, alkenes, hopanes, and steranes), PAHs, thiazols, n-alkanols, polyols, some fragrant compounds, sugars, triterpenoids, sterols, phenolic constituents, phthalate plasticisers and several types of acids, among others. The relationship between airborne particulate organic constituents and organic matter in tyre debris is discussed. The detection of compounds that have been extensively used as biomass burning tracers (e.g. retene, dehydroabietic acid and levoglucosan) in both the shredded tiny tyre chips and the wear particles from the interaction between tyres and pavement puts into question their uniqueness as markers of wood combustion. Trace and major elements accounted for about 5% of the mass of the tyre fragments but represented 15–18% of the PM10 from wear, denoting the contribution of mineral elements from the pavement. Sulphur and zinc were abundant constituents in all samples.
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| 64. |
- Alänge, Sverker, 1951, et al.
(författare)
-
ISO 9000: Erfarenheter från certifierade företag
- 1993
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Idag har många svenska företag fått ISO 9000-certifikat genom tredjeparts bedömning, antingen via SIS, Norsk Veritas, Lloyd's eller British Standard Institute. De flesta företagen har antingen certifierats enligt ISO 9001 eller ISO 9002. I september 1992 hade 34 företag certifierats genom Norsk Veritas och det fanns 72 certifierade företag på SIS lista.Det finns dock många olika synpunkter angående värdet av en certifiering. Vissa anser att den är grundläggande för ett gott kvalitetsarbete och andra anser att det verkar vara en krånglig pappersexercis utan större inverkan på kvalitetsresultatet. Juran väckte en del uppståndelse och eftertanke när han 1989 sa "Se gärna till att uppfylla ISO 9000 men låt det inte störa kvalitetsarbetet".Denna rapport baseras på en undersökning för att ta reda på hur det verkligen förhåller sig i svenska företag. Den är utförd av teknologer som deltagit i en kurs i "Industriell kvalitetsteknik" vid Chalmers tekniska högskola. Var och en av teknologerna har haft som uppgift att ta kontakt med ett svenskt företag som certifierats enligt ISO 9001 eller ISO 9002. Uppgiften gällde att undersöka vilka positiva och negativa erfarenheter de certifierade företagen har av certifieringsprocessen och vilka resultat de uppnått internt och externt på grund av ISO 9000.Teknologerna delades in i grupper om 5-7 personer där var och en ringde ett företag under november-december 1992. Därefter sammanställde varje grupp en liten rapport baserad på 5-7 intervjuer. De analyserade de viktigaste positiva och negativa synpunkterna från dessa intervjuer. De undersökte om det fanns något gemensamt i svaren, eller om företagen hade olika erfarenheter och då försökte de komma fram till vad detta kunde bero på.Genom den egna direkta kontakten med ett företag och den gruppvisa diskussionen och författandet av en rapport har teknologerna kunna skaffa sig egna kunskaper om ISO 9000. I storgrupp presenterade därefter de olika smågrupperna sina rapporter och diskuterade resultaten. Baserat på denna diskussion, smågruppsrapporterna och ifyllda intervjuformulär har därefter tre teknologer sammanställt resultatet till föreliggande rapport.
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| 65. |
- Amato, Fulvio, et al.
(författare)
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Urban air quality : The challenge of traffic non-exhaust emissions
- 2014
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Ingår i: Journal of Hazardous Materials. - : Elsevier BV. - 0304-3894 .- 1873-3336. ; 275, s. 31-36
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Tidskriftsartikel (refereegranskat)abstract
- About 400,000 premature adult deaths attributable to air pollution occur each year in the European Region. Road transport emissions account for a significant share of this burden. While important technological improvements have been made for reducing particulate matter (PM) emissions from motor exhausts, no actions are currently in place to reduce the non-exhaust part of emissions such as those from brake wear, road wear, tyre wear and road dust resuspension. These "non-exhaust" sources contribute easily as much and often more than the tailpipe exhaust to the ambient air PM concentrations in cities, and their relative contribution to ambient PM is destined to increase in the future, posing obvious research and policy challenges.This review highlights the major and more recent research findings in four complementary fields of research and seeks to identify the current gaps in research and policy with regard to non-exhaust emissions. The objective of this article is to encourage and direct future research towards an improved understanding on the relationship between emissions, concentrations, exposure and health impact and on the effectiveness of potential remediation measures in the urban environment.
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| 66. |
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| 67. |
- Ammenberg, Jonas, 1973-, et al.
(författare)
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Perspectives on biomethane as a transport fuel within acircular economy, energy, and environmental system
- 2021
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The literature indicates that the life cycle costs of biomethane fueled light vehicles may be 15 to 20% highe rthan for similar petrol and diesel fueled vehicles, while liquid biomethane fueled heavy duty trucks may have similar life cycle costs to diesel. However, such an analysis can be two dimensional and limited in the message it conveys. On one hand the acceptance of diesel fueled trucks and buses will be limited due to the climate emergency and air pollution and after 2030 diesel may not be the competition for biomethane anymore. On the otherhand, biomethane production is part of a larger circular economy, energy, and environmental system. It is verydifficult to divorce the energy vector, biomethane, from the system through which it is produced. In essence biomethane can be considered as one of the products or services of a broad biogas system.An advantage of biogas is that it can be produced from most wet organic wastes or by-products, includingfor food waste, animal by-products, (such as manure), agricultural residues, sewage sludge, industrial biowaste (such as from slaughterhouses and food and beverage processing industries). Biogas production is an element in the environmental management of such wastes; biogas plants can also deliver digestate, which contains most ofthe nutrients in the feedstock and can be an excellent biofertilizer. In addition, it is possible to utilize the carbon dioxide removed in upgrading biogas to biomethane as a product with added value. The resource of biomethane is very significant in considering the vast amounts of organic wastes landfilled around the world each year, that instead could be used to produce biogas, biofertilizers and food grade CO2 while improving the environment through reduced fugitive methane emissions and improved water quality. Furthermore, the application of biogas systems in bio-industrial contexts (such as paper mills, food production facilities, or other types of biorefineries) has huge potential to decarbonize industry while significantly increasing the resource of biomethane. Due to the multifunctionality of biomethane solutions, broad assessment methods are needed to grasp thewide spectrum of relevant factors when comparing different technologies:• Biomethane has a competitive performance compared with fossil fuels and other biofuels on a whole lifecycle analysis and is particularly suited to long distance heavy vehicles.• Biomethane from manure, residues, waste & catch crops is estimated to have low GHG emissions ascompared to other renewable fuels.• Biomethane may contribute to reduced air pollution in comparison with diesel, petrol, and other biofuels.• Biomethane can contribute to a substantial reduction in acidification compared with fossil fuels.• Biomethane may contribute to significantly reduced noise levels in comparison with diesel heavy goodsvehicles.• Well-designed and applied biogas systems may be essential to transform conventional farming to moresustainable farming and to organic farming.• Common types of biogas solutions provide essential sociotechnical systems services as components ofsystems for waste and (waste) water management.• Biogas solutions may importantly contribute to improved energy supply/security and flexibility.Natural gas systems should be a facilitator of the introduction of biomethane for transport, but the sustainability problems associated with natural gas negatively impact the view of biomethane. This is where arguments amongst the renewable sector actors can hinder progress. Biomethane and (power to methane) can utilize the existing gas grid and accelerate progress to decarbonization of the overall energy sector beyond just electricity and also to decarbonize chemical (such as ammonia and methanol) and steel production. This should be advantageous especially when realizing that more energy is procured from the natural gas grid than the electricity gridin the EU and the US; however, suggestions that biomethane is only greenwashing the natural gas industry, and in doing so extending the lifetime of natural gas, greatly impedes this progress.This report provides exemplars of very good biomethane based transport solutions, with a high technologicalreadiness level for all elements of the chain from production to vehicles. Transport biomethane sits well in the broad circular economy, energy, and environmental system providing services across a range of sectors including reduction in fugitive methane emissions from slurries, treatment of residues, environmental protection, provision of biofertiliser, provision of food grade CO2 and a fuel readily available for long distance heavy haulage. What we do not have is time to postpone the sustainable implementation of such circular economy biomethane systems as the climate emergency will not wait for absolutely perfect zero emission solutions; should they exist.
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| 68. |
- Andersson, Claes, 1978-
(författare)
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Fusing Domain Knowledge with Data : Applications in Bioinformatics
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Massively parallel measurement techniques can be used for generating hypotheses about the molecular underpinnings of a biological systems. This thesis investigates how domain knowledge can be fused to data from different sources in order to generate more sophisticated hypotheses and improved analyses. We find our applications in the related fields of cell cycle regulation and cancer chemotherapy. In our cell cycle studies we design a detector of periodic expression and use it to generate hypotheses about transcriptional regulation during the course of the cell cycle in synchronized yeast cultures as well as investigate if domain knowledge about gene function can explain whether a gene is periodically expressed or not. We then generate hypotheses that suggest how periodic expression that depends on how the cells were perturbed into synchrony are regulated. The hypotheses suggest where and which transcription factors bind upstreams of genes that are regulated by the cell cycle. In our cancer chemotherapy investigations we first study how a method for identifiyng co-regulated genes associated with chemoresponse to drugs in cell lines is affected by domain knowledge about the genetic relationships between the cell lines. We then turn our attention to problems that arise in microarray based predictive medicine, were there typically are few samples available for learning the predictor and study two different means of alleviating the inherent trade-off betweeen allocation of design and test samples. First we investigate whether independent tests on the design data can be used for improving estimates of a predictors performance without inflicting a bias in the estimate. Then, motivated by recent developments in microarray based predictive medicine, we propose an algorithm that can use unlabeled data for selecting features and consequently improve predictor performance without wasting valuable labeled data.
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| 69. |
- Andersson, Claes R., et al.
(författare)
-
Bayesian detection of periodic mRNA time profiles withouth use of training examples
- 2006
-
Ingår i: BMC Bioinformatics. - : Springer Science and Business Media LLC. - 1471-2105. ; 7, s. 63-
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Detection of periodically expressed genes from microarray data without use of known periodic and non-periodic training examples is an important problem, e.g. for identifying genes regulated by the cell-cycle in poorly characterised organisms. Commonly the investigator is only interested in genes expressed at a particular frequency that characterizes the process under study but this frequency is seldom exactly known. Previously proposed detector designs require access to labelled training examples and do not allow systematic incorporation of diffuse prior knowledge available about the period time. RESULTS: A learning-free Bayesian detector that does not rely on labelled training examples and allows incorporation of prior knowledge about the period time is introduced. It is shown to outperform two recently proposed alternative learning-free detectors on simulated data generated with models that are different from the one used for detector design. Results from applying the detector to mRNA expression time profiles from S. cerevisiae showsthat the genes detected as periodically expressed only contain a small fraction of the cell-cycle genes inferred from mutant phenotype. For example, when the probability of false alarm was equal to 7%, only 12% of the cell-cycle genes were detected. The genes detected as periodically expressed were found to have a statistically significant overrepresentation of known cell-cycle regulated sequence motifs. One known sequence motif and 18 putative motifs, previously not associated with periodic expression, were also over represented. CONCLUSION: In comparison with recently proposed alternative learning-free detectors for periodic gene expression, Bayesian inference allows systematic incorporation of diffuse a priori knowledge about, e.g. the period time. This results in relative performance improvements due to increased robustness against errors in the underlying assumptions. Results from applying the detector to mRNA expression time profiles from S. cerevisiae include several new findings that deserve further experimental studies.
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| 70. |
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