| 1. |
- Romano, Luigi
(författare)
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OC generator
- 2023
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The present code can be used to synthesise stochastic operating cycles (sOCs) and deterministic operating cycles (dOCs) for longitudinal vehicle dynamics simulations. The files need to be integrated with the WAFO package.
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| 2. |
- Nybacka, Mikael, et al.
(författare)
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Project: CASTT - Centre for Automotive Systems Technologies and Testing
- 2007
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Annan publikation (populärvet., debatt m.m.)abstract
- Through the Centre for Automotive Systems Technologies and Testing, Luleå University of Technology aims to first of all support automotive winter testing in Northern Sweden. This means to support the local automotive test entrepreneurs and through them their customers: the car manufacturers and their suppliers. To succeed in this task, the center relies on the university's areas of leading research and most importantly on the cooperation between those areas.
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| 3. |
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| 4. |
- Sh. Sichani, Matin, et al.
(författare)
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An approximate analytical method to solve frictionless contact between elastic bodies of revolution
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- An analytical method is proposed for calculating the contact patch and pressure distribution between two elastic bodies generated by rotating arbitrary profiles about parallel axes. The elastic deformation is approximated based on the separation between the bodies in contact. This makes it possible to estimate the contact patch analytically. The contact pressure distribution, in the direction perpendicular to the axes of rotation, is assumed to be elliptic with its maximum calculated by applying Hertz solution locally. The results are exact for contact between two ellipsoids when compared against Hertz's. In non-elliptic contact cases (e.g. in wheel-rail contact) good agreement is achieved in comparison to more accurate but computationally expensive methods such as Kalker's variational method (CONTACT algorithm). Compared to simplified non-elliptic contact methods based on virtual penetration, the calculated contact patch and pressure distribution are markedly improved. The computational cost of the proposed method is significantly lower than the more detailed methods, making it worthwhile to be applied to rolling contact in rail vehicle dynamic simulation.
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| 5. |
- Lundberg, Oskar, 1980-, et al.
(författare)
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A compact internal drum test rig for measurements of rolling contact forces between a single treadblock and a substrate
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- A novel test rig design is presented which enables detailed studies of the three force components generated in the impact and release phase of rolling contact between a tyre tread block and a substrate. The design of the compact internal drum test rig provides realistic impact and release angles for the tread block-substrate contact and enables force measurements at high rolling speeds with a high signal-to-noise ratio. Measurements of the rolling contact forces are presented for different values of rolling velocity, static pre-load and acceleration. It is demonstrated that this test rig provides results which contribute to the understanding of tyre--road interaction and can be used as input to modelling-based development of both tyres and roads aiming for improved handling, safety, energy efficiency and comfort.
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| 6. |
- Lundberg, Oskar, 1980-
(författare)
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An experimental study on the influence of substrate roughness on the friction of a tread block in rolling and sliding contact
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- An experimental study of the friction coefficient is performed for a tyre tread block in rolling and sliding contact with two different asphalt substrates, a smooth aluminium and an anti-slip tape substrate. The sliding friction coefficient is for all substrates seen to increase as the sliding velocity is increasing. However, the slope for the increasing friction as a function of sliding velocity differs significantly between the substrates, presumably due to differences in the respective contribution from adhesive and hysteresis friction mechanisms. Parametric studies of the rolling friction show that the choice of substrate as well as the rolling velocity and the slip ratio has significant influence on the resulting friction coefficient. A linear relation is observed between the longitudinal rolling friction coefficient measured at low values of slip ratio and the sliding friction coefficient measured at low sliding velocities. For the tests of rolling friction at higher values of slip, stick\textendash slip conditions are observed for which the frequency content of the longitudinal force is seen to vary substantially between the different operating conditions and choice of substrate. The outcomes of this study can potentially be used to improve future tyre\textendash road contacts with respect to wear, traction and noise generation.
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| 7. |
- Lundberg, Oskar, 1980-
(författare)
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Friction of a rubber tread block in rolling and sliding contact with asphalt---An experimental study
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The longitudinal and vertical contact force history of an individual truck tyre tread block in rolling contact with an asphalt surface is experimentally investigated. Different rolling velocities up to approximately 60 km/h and different amount of slip ratios are studied with the use of a novel compact internal drum test rig, leading to results with high signal-to-noise ratio. Interestingly, the longitudinal rolling contact force component and the corresponding friction coefficient exhibit substantial variations not only between the different operating conditions, but also along the contact length of individual impacts. In addition, separate investigatory characterisations for the dynamic elastic deformation of the rubber and for the sliding friction of the rubber\textendash asphalt contact are found to be useful; they provide approximate input values for an initial, promising attempt to separate the contribution from elastic deformation and that from sliding friction. Conclusively, valuable insights are gained which has the potential to further reduce the gap between physically based modelling of friction and empirically based knowledge, which are commonly used in vehicle and tyre industry.
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| 8. |
- Skagestad, Ragnhild, 1978, et al.
(författare)
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GCCSI Webinar: Cutting Cost of CO2 Capture in Process Industry (CO2stCap) Project overview & first results for partial CO2 capture at integrated steelworks
- 2017
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- GCCSI Webinar: Cutting Cost of CO2 Capture in Process Industry (CO2stCap) Project overview & first results for partial CO2 capture at integrated steelworks This publication has the format of a webinar: The CO2StCap project is a four year initiative carried out by industry and academic partners with the aim of reducing capture costs from CO2 intensive industries (more information here). The project, led by Tel-Tek, is based on the idea that cost reduction is possible by capturing only a share of the CO2 emissions from a given facility, instead of striving for maximized capture rates. This can be done in multiple ways, for instance by capturing only from the largest CO2 sources at individual multi-stack sites utilising cheap waste heat or adapting the capture volumes to seasonal changes in operations. The main focus of this research is to perform techno-economic analyses for multiple partial CO2 capture concepts in order to identify economic optimums between cost and volumes captured. In total for four different case studies are developed for cement, iron & steel, pulp & paper and ferroalloys industries. The first part of the webinar gave an overview of the project with insights into the cost estimation method used. The second part presented the iron & steel industry case study based on the Lulea site in Sweden, for which waste-heat mapping methodology has been used to assess the potential for partial capture via MEA-absorption. Capture costs for different CO2 sources were discussed, demonstrating the viability of partial capture in an integrated steelworks.
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| 9. |
- Svensson, Elin, 1980, et al.
(författare)
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A Scenario-Based Stochastic Programming Model for the Optimization of Process Integration Opportunities in a Pulp Mill
- 2008
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Several studies show that substantial industrial energy savings can be achieved through process integration. The returns on such investments are, however, uncertain because of uncertainties in future energy prices and policies. This article presents a stochastic mixed-integer programming approach which enables the identification of robust process integration investments under uncertainty. The proposed approach is applied to the case of a pulp mill for which the complete optimization model is presented. The model is a scenario-based multistage stochastic programming model with the objective of maximizing the net present value of the investments. The model also enables the optimization of investment timing. We show as one important result that the probability distribution can be varied rather much without a change in the optimal solution. This implies that the stochastic programming approach is a valuable tool although the true probabilities for the future scenarios are not known.
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| 10. |
- Tasala Gradin, Katja, 1976-, et al.
(författare)
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Comparative Life Cycle Assessment of Car Disc Brake Systems : case study results and methodological options for comparative LCAs
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- PurposeTwo Life Cycle Assessment (LCA) studies comparing a new low-particulate- matter-emission disc brake and a reference disc brake are presented. The purpose is to identify the difference in environmental impacts due to a material change in the new disc brake parts. Additionally, the validity of the simplification called comparative LCA with an omission of parts is investigated. This is done by comparing results between the simplified and the full LCA model.MethodsThe two disc brakes, new disc brake and reference disc brake, are assessed according to the LCA ISO standards. The ReCiPe 2016 Midpoint (Hierarchist) impact assessment method is chosen. Simplifying a comparative LCA is possible. All of the LCA parts that are identical between the two compared products can be omitted, and only the ones that differ need to be assessed. In this paper, this simplification is called comparative LCA with an omission of parts and is defined as an isolated model of the full LCA system. The epistemology is borrowed from economics research on models and adapted to LCA models. An objective is to support discussions around the methodology of the simplification that is lacking in published LCA research.Results and discussionThe comparative impacts are analysed over seventeen impact categories. The new disc brake alternative uses more resources during the manufacture of one disc compared to the reference disc brake alternative. The shorter life length of the reference disc demands a higher number of spare part discs to fulfil the same functional unit, but this impact is reduced due to material recycling. The new disc brake contributing impacts are connected primarily to the coating and secondly to the pad manufacture and materials. The external validity of the isolated LCA model is investigated by comparing the results of the two LCA models. The impact differences are identical independent of the LCA model. Hence, the purpose of the study can be fulfilled, and the isolated model is valid.ConclusionsBoth LCA models, simplified and full, reveal that the new disc brake has limited environmental advantages. The omission of identical parts makes it more difficult to determine if an impact is significant or insignificant. There are no arguments that point to that the external validity is compromised for the ‘comparative LCA with omitted parts’, compared to the full LCA. The simplification seems to be reasonable from a short-term perspective
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