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  • Presentation: 2018-03-01 10:00 F3, Stockholm
    Lundberg, Joacim
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials. VTI - Statens Väg- och Transportforskningsinstitut.
    Non-Exhaust PM10 and Road Dust2018Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Non-exhaust PM10 is an issue in the urban environment linked to health issues. Emissions of non-exhaust PM10 is relatable to pavement properties. Also of importance is resuspension of road dust stored from surfaces. This depends on the traffic and metrological conditions. Given this, the purpose of the thesis was to give an overview limited to Sweden and the Nordic countries regarding non-exhaust PM10 emissions and road dust.

    The overview includes how particles are related to human health. Also included is the principle of how particles are emitted from road surface and tyre interaction, both directly and through resuspension of road dust. This thesis also includes an overview of how the use of studded tyres impact on asphalt surfacings and how the properties of the materials used impact on the abrasion wear. This is then linked to the emissions of non-exhaust particles. Further described is how measurements can be done of ambient particles and road dust, followed on two major models for road abrasion wear and non-exhaust PM prediction. Also included is how road operation, e.g. traction sanding and dust binding, influence the particle emissions together with other options to reduce the emissions through, e.g. limiting the use of studded tyres.

    One special issue discussed in this thesis is the lack of holistic view regarding the environmental problems in the urban environment with focus on particle emissions and road noise emissions, both from the road surface and tyre interaction. Currently the most problematic issue is prioritized and the resulting solution to that specific problem might increase other problems.

    This thesis shows that much knowledge is available regarding non-exhaust PM10 emissions and road dust, but also that several knowledge gaps exists. Several suggestions on further studies is given together with a brief overview on the continued work forward from this thesis.

  • Presentation: 2018-03-08 10:00 B1, Stockholm
    Vieira, Tiago
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials. VTI.
    Tyre-road Interaction: a holistic approach to noise and rolling resistance2018Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Energy dissipation, fuel consumption, real-estate property prices and health issues are some of the aspects related to the tyre/pavement interaction and its functional properties of rolling resistance and noise. The first two aspects are affected by the tyre/road interaction as energy is dissipated mostly by hysteretic losses as the tyre is subjected to dynamic deformations when contacting the pavement surface. The other effect of this contact system that is analysed in this thesis is noise. Excessive noise exposure leads to a decrease in real-estate property values and even health issues such as increased blood pressure, sleep disturbance, cognitive impairment in children, among others.

    To mitigate such issues, a good understanding of the underlying causes is crucial and therefore a holistic approach was used to analyse the contact interaction in a more comprehensive way, encompassing the pavement, tyre, environmental and contact media (contaminations). Both noise and rolling resistance were analysed after subjecting the contact system to controlled interventions in one variable while maintaining the other variables constant and then comparing to a reference condition. In the first part of the investigative work, different tyres were tested while maintaining the pavement, environment and contact media constant, allowing an evaluation of the impact of winter tyres on noise and rolling resistance. In the second part, an intervention in the pavement was applied while maintaining the other variables constant. allowing an evaluation of the impact of surface grinding on noise and rolling resistance.

    The first part quantified how noisier studded tyres are in comparison to non-studded tyres, yet no substantial difference in rolling resistance was found. The second part revealed the potential of the horizontal grinding to reduce noise and rolling resistance, having a limitation, on the duration of such effects, especially for Swedish roads where studded tyres are used.

  • Presentation: 2018-03-14 10:15 Seminarierummet, KTH Hållfasthetslära, 100 44 Stockholm
    Everitt, Carl-Magnus
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.).
    Initiation of rolling contact fatigue from asperities in elastohydrodynamic lubricated contacts2018Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Rolling contacts are utilized in many technical applications, both in bearings and in the contact between gear teeth. These components are often highly loaded, which makes them susceptible to suffer from rolling contact fatigue. This work focuses on the rolling contact fatigue mechanism of pitting. In order to attain a better understanding of why pitting initiates and grows, detailed simulations of rolling contacts have been performed. In particular the contact between two gears in a truck retarder was here used as a case study. The investigated contact experienced elastohydrodynamic lubrication conditions since the load was high enough to causes the surfaces in contact to deform and the viscosity of the lubricant to increase significantly.

    In Paper A it was investigated if surface irregularities in the size of the surface roughness are large enough to cause surface initiated fatigue. The investigation focused on the pitch line since small surface initiated pits were found here even though there was no slip present. Since there were pits present at the pitch line, it is important that the theories of pitting can explain the development of pits also in the absence of slip. The conclusion of the work was that surface irregularities of the size of normal surface roughness are enough to cause surface initiated fatigue at the pitch line.

    In Paper B it was investigated why pits are more likely to initiate in the dedendum of pinion gears than in the addendum. In both areas slip is present but in different directions. In the dedendum the friction from slip is against the rolling direction which enhances the risk for pitting. The investigation was performed by studying the effect of the temperature rise in the contact caused by the slip. The conclusion drawn was that the temperature rise in the contact explained why pitting was more common in the dedendum than in the addendum.

  • Presentation: 2018-03-14 13:27 M311, Stockholm
    Harahap, Fumi
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    An evaluation of biodiesel policies: The case of palm oil agro-industry in Indonesia2018Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Oil palm has flourished as an economically vital crop in Indonesia given its use in both food and non-food products (including biodiesel) for domestic and export markets. However, the expansion of oil palm plantations in Indonesia is controversial. While the crop generates fiscal earnings for the country, and regular income streams for farmers and companies, oil palm plantation expansion is claimed to cause deforestation, environmental degradation and biodiversity losses. At the same time, there is a national target to reduce GHG emissions from land use change and the production of palm oil. Climate change mitigation goals also include ambitious targets to blend biodiesel with fossil diesel in various economic sectors.

    This thesis looks at the palm oil agro-industry, from oil palm plantation to crude palm oil (CPO) production, and CPO based biodiesel production. It proposes a policy evaluation to verify policy implications in relation to the issue of land use allocation, and the poor profitability in palm oil biodiesel production. The overarching objective is to evaluate the effectiveness of prevailing policies used to promote the palm oil agro-industry for biodiesel production in Indonesia.

    The thesis is framed by policy research and ex-post policy evaluation. The focus is on the process of policy formulation and implementation, rather than outcome evaluation. Two specific analytical frameworks are used to answer the research questions while addressing the criteria of effectiveness in policy evaluation: (i) policy coherence analysis and (ii) life cycle cost analysis. Qualitative indicators are used to measure the coherence of biofuel policy with other sectoral policies (agriculture, climate and forestry) in relation to land allocation. Quantitative economic indicators are used to compare the costs and benefits of conventional palm oil biodiesel production with a biorefinery conceptual plant.

    There are valuable lessons to be learnt from this policy evaluation. The results indicate areas in which policy effectiveness can be improved. For land allocation, adjustments and improvements in policy formulation and implementation are crucial. Uncertainties when it comes to the allocation of land to meet multi sectoral policy goals are to be addressed by clarifying land use definitions and categories, which should be backed up by consistent land use definitions in various policy documents. The dual land classification presently applied should move towards a single land classification, linking actual landscape coverage and the legal status of the land. Policy information and guidance across sectoral policies should be compiled in a single database. Such a publicly available database would help enhance the efficiency of land allocation for multiple policy purposes. More importantly, the formulation of biodiesel policy has to engage various sectoral policies that compete for the same resources.

    The biorefinery conceptual plant allows the reduction of government subsidies, while also providing a pathway to enhance the use of renewable energy and reduce GHG emissions. Policies have been designed to enhance plant profits through the improved utilisation of biomass residues in the palm oil mill for energy generation and composting. However, the low implementation rate of policies indicates the need to improve the effectiveness of policy implementation, and therefore the need for better monitoring processes, and possibly more stringent consequences for non-compliance.

  • Presentation: 2018-03-15 10:00 Room 643 (Albert Danielsson), Stockholm
    Jazairy, Amer
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.). University of Gävle, Sweden.
    Exploring shippers, logistics service providers and their relationships in facilitating green logistics2018Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The logistics industry causes various harms to the environment. The literature assigns the main responsibility for alleviating such harms to two supply chain actors: shippers (logistics buyers) and logistics service providers (LSPs), which motivated studying them in this thesis. Specifically, this thesis explores and identifies how green logistics practices can be facilitated through aligning both actors throughout the different phases of their relationships. Two studies are compiled. The first study is based on five distinct cases -- three shippers and five LSPs, providing the basis for two papers: (i) one that analyses the institutional pressures (regulatory, market, competitive) on shippers to purchase green logistics services, and on LSPs to provide these services, and (ii) one that investigates the two actors’ stances on environmental concerns in the four key logistics purchasing phases (request for proposal, negotiations, contracting, execution), while proposing ways to align their efforts along such phases. The second study covers a single case of a dyadic relationship between a shipper and its LSP, handling enhancing logistics performance (cost efficiency, on-time delivery) in the early stages of their relationship. The findings indicate a general lack of regulatory pressure in driving shippers and LSPs to engage in green logistics, contrasted by a long-term influence of competitive pressure and a prevalent influence of market pressure. It was also found that both actors must put substantial efforts in the beginning of their relationships to reach a mutual business understanding, allowing performance and green enhancements. In the execution, it was found that both partners should regularly communicate performance metrics while modifying working standards, which would also support their green practices. For practitioners, insights are offered to align shippers’ and LSPs’ efforts within their relationships to attain positive performance and green outcomes.

  • Presentation: 2018-03-16 10:00 Q2, Stockholm
    Verginis, Christos
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control.
    Planning and Control of Cooperative Multi-Agent Manipulator-Endowed Systems2018Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Multi-agent planning and control is an active and increasingly studied topic of research, with many practical applications, such as rescue missions, security, surveillance, and transportation. More specifically, cases that involve complex manipulator-endowed systems  deserve extra attention due to potential complex cooperative manipulation tasks and their interaction with the environment. This thesis addresses the problem of cooperative motion- and task-planning of multi-agent and multi-agent-object systems under complex specifications expressed as temporal logic formulas. We consider manipulator-endowed robotic agents that can coordinate in order to perform, among other tasks, cooperative object manipulation/transportation. Our approach is based on the integration of tools from the following areas: multi-agent systems, cooperative object manipulation, discrete abstraction design of multi-agent-object systems, and formal verification. More specifically, we divide the main problem into three different parts.The first part is devoted to the control design for the formation control of a team of rigid-bodies, motivated by its application to cooperative manipulation schemes. We propose decentralized control protocols such that desired position and orientation-based formation between neighboring agents is achieved. Moreover, inter-agent collisions and connectivity breaks are guaranteed to be avoided. In the second part, we design continuous control laws explicitly for the cooperative manipulation/transportation of an object by a team of robotic agents. Firstly, we propose robust decentralized controllers for the trajectory tracking of the object's center of mass.  Secondly, we design model predictive control-based controllers for the transportation of the object with collision and singularity constraints. In the third part, we design discrete representations of multi-agent continuous systems and synthesize hybrid controllers for the satisfaction of complex tasks expressed as temporal logic formulas. We achieve this by combining the results of the previous parts and by proposing appropriate trajectory tracking- and potential field-based continuous control laws for the transitions of the agents among the discrete states. We consider teams of unmanned aerial vehicles and mobile manipulators as well as multi-agent-object systems where the specifications of the objects are also taken into account.Numerical simulations and experimental results verify the claimed results.

  • Presentation: 2018-03-16 14:00 F11, Stockholm
    Altafi, Nasrin
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.).
    Lefschetz Properties of Monomial Ideals2018Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis concerns the study of the Lefschetz properties of artinian monomial algebras. An artinian algebra is said to satisfy the strong Lefschetz property if multiplication by all powers of a general linear form has maximal rank in every degree. If it holds for the first power it is said to have the weak Lefschetz property (WLP).

    In the first paper, we study the Lefschetz properties of monomial algebras by studying their minimal free resolutions. In particular, we give an afirmative answer to an specific case of a conjecture by Eisenbud, Huneke and Ulrich for algebras having almost linear resolutions. Since many algebras are expected to have the Lefschetz properties, studying algebras failing the Lefschetz properties is of a great interest. In the second paper, we provide sharp lower bounds for the number of generators of monomial ideals failing the WLP extending a result by Mezzetti and Miró-Roig which provides upper bounds for such ideals. In the second paper, we also study the WLP of ideals generated by forms of a certain degree invariant under an action of a cyclic group. We give a complete classication of such ideals satisfying the WLP in terms of the representation of the group generalizing a result by Mezzetti and Miró-Roig.