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  • 1.
    Cebecauer, Matej
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport planning.
    Gundlegård, David
    Department of Science and Technology,Linköping University.
    Jenelius, Erik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport planning.
    Burghout, Wilco
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport planning.
    3D Speed Maps and Mean Observations Vectors for Short-Term Urban Traffic Prediction2019In: TRB Annual Meeting Online, Washington DC, US, 2019, p. 1-20Conference paper (Refereed)
    Abstract [en]

    City-wide travel time prediction in real-time is an important enabler for efficient use of the road network. It can be used in traveler information to enable more efficient routing of individual vehicles as well as decision support for traffic management applications such as directed information campaigns or incident management. 3D speed maps have been shown to be a promising methodology for revealing day-to-day regularities of city-level travel times and possibly also for short-term prediction. In this paper, we aim to further evaluate and benchmark the use of 3D speed maps for short-term travel time prediction and to enable scenario-based evaluation of traffic management actions we also evaluate the framework for traffic flow prediction. The 3D speed map methodology is adapted to short-term prediction and benchmarked against historical mean as well as against Probabilistic Principal Component Analysis (PPCA). The benchmarking and analysis are made using one year of travel time and traffic flow data for the city of Stockholm, Sweden. The result of the case study shows very promising results of the 3D speed map methodology for short-term prediction of both travel times and traffic flows. The modified version of the 3D speed map prediction outperforms the historical mean prediction as well as the PPCA method. Further work includes an extended evaluation of the method for different conditions in terms of underlying sensor infrastructure, preprocessing and spatio-temporal aggregation as well as benchmarking against other prediction methods.

  • 2.
    Warg, Jennifer
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport Planning, Economics and Engineering.
    Ait-Ali, Abderrahman
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport Planning, Economics and Engineering.
    Eliasson, Jonas
    Assessment of Commuter Train Timetables Including Transfers2019In: 21st EURO Working Group on Transportation Meeting, EWGT 2018, 17th – 19th September 2018, Braunschweig, Germany, 2019, Vol. 37, p. 11-18Conference paper (Refereed)
    Abstract [en]

    Many railway networks suffer from high capacity utilisation. For scheduling all services, adjustments to the desired slots are often needed. Such adjustments might lead to longer travel times, crowded trains, longer waiting times for boarding and for transfers. All of this has an important socio-economic impact on both travellers and train operators. This raises the question of the socio-economic assessment of changes in commuter train timetables including transfers. Thus, the aim of this study is to evaluate the effects of adjustments of commuter train timetables on the traveller (i.e. consumer costs) and the train operator (i.e. producer costs). These costs are estimated based on all train trips and operations in the network. In a case study, the effect of changes in departure times (resulting in non-regular interval timetables) is analysed. Further, the price of cancelling a two-way service during different times of the day is compared. The results show that changing departure times can both decrease and increase the total costs, and that regularity for parallel services might not be as important as expected if it is kept for each separate service. For the second study, waiting times for transfers were indicated to have a (too) large impact which can lead to misleading results and might be adjusted in future work. The model is adequate for such kind of questions but needs some more adjustments. For railway networks with dense and heterogeneous traffic (as is the case in Sweden), the contributions of this model are useful for making the challenging timetabling process easier and commuter train services less costly.

  • 3.
    Eriksson, Daniel
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Malm, Richard
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Hellgren, Rikard
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Assessment of frost damage in hydraulic structures using a hygro-thermo-mechanical multiphase model2019In: Sustainable and Safe Dams Around the World / [ed] Jean-Pierre Tournier, Tony Bennett & Johanne Bibeau, 2019, Vol. 2, p. 332-346Conference paper (Refereed)
    Abstract [en]

    This paper presents an extension of a novel hygro-thermo-mechanical multiphase model for simulation of freezing of partially saturated air-entrained concrete on the structural scale to account for the effect of damage in the material. The model is applied in an example which investigates the extent and severity of frost damage caused by extremely cold climate conditions in a typical concrete wall in a waterway constructed with air-entrained concrete. The results were concluded to comply with observations made in experimental work and testing of freezing air-entrained concrete under exposure conditions similar to those in hydraulic structures. Furthermore, the results indicate that the effect of short periods of time with high rates of freezing was rather small on the obtained damage. Additionally, increasing the depth of the boundary region with an initially high degree of water saturation on the upstream side had also a rather small effect on the damaged zone.

  • 4.
    Wang, Ruoqi
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Leander, John
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Karoumi, Raid
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Comparison of simulation methods applied to steel bridge reliability evaluations2019Conference paper (Refereed)
    Abstract [en]

    Steel bridges are in general subjected to fatigue deterioration and the structural reliability of bridges will thus reduce over time. There are multiple simulation-based procedures available to perform structural probabilistic studies with several classes of uncertainty taken into account. Since the crack propagation is highly nonlinear and the limit state function (LSF) is multi-dimensional, it imposes specific demands on the simulation methods. Monte Carlo simulation (MCS) has been widely applied in various of fields, however, it requires a great amount of samples and long computation time to reach a high level of accuracy. A more advanced method, Subset Simulation (SS), compensates this shortage. It calculates the product of conditional probabilities of several chosen intermediate failure events. In this paper, the performance of each method was evaluated and compared against fatigue deterioration for aselected bridge detail. A probabilistic model was defined and both prior and updated reliability estimation were performed. The results showed that SS is a good option to deal with fatigue problem with high nonlinearity and multi-dimensional LSF, and shows outstanding time efficiency compared to MCS to reach a comparable accuracy.

  • 5.
    Wersäll, Carl
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Åkesson, Fredrik
    Persson, Andreas
    Dynamic roller characteristics and CCC using automatic frequency control2019Conference paper (Refereed)
  • 6.
    Olsson, Lars
    et al.
    Geostatistik AB.
    Spross, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Hintze, Staffan
    NCC.
    Stille, Håkan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Båtelsson, Olle
    Trafikverket.
    Framtidens riskhantering – nu med systemförståelse2019Conference paper (Other (popular science, discussion, etc.))
    Abstract [sv]

    Geoteknikern hanterar i sin vardag många och ofta stora risker. Men trots att kostnaden för negativa utfall av geotekniska risker årligen bedöms ligga på flera miljarder kronor, används tillgängliga verktyg för strukturerad riskhantering sparsamt. I ett SBUF-projekt har vi tagit fram en vägledning för hur sådana verktyg kan användas i praktiken. Vi har i denna vägledning särskilt fokuserat på den för riskhanteringen så viktiga systemförståelsen av det geotekniska sammanhanget som man verkar i. Denna artikel är en sammanfattande kortversion av den slutrapport som författarna skrivit inom ramen för SBUF-projektet.

  • 7.
    Spross, Johan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Stille, Håkan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Johansson, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Palmström, Arild
    Rock Mass AS.
    Hur ska bergbyggande kunna inkluderas i Eurokod 7: How to include rock engineering in Eurocode 72019Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    Sweden, among other countries, has chosen not to apply Eurocode 7 to rock engineer­ing design. However, Eurocode 7 is currently under revision, with one purpose being to improve its applicability to rock engineering. Such a revision would however require that the code accommodates the current principles of rock engineering design and exe­cution, since rock engineering in many cases fundamentally differs from other types of construction. In this presentation, we give our view on how a design code for rock engineering needs to be organized, in order to ensure that new rock engineering struc­tures become both sufficiently safe and cost-effectively constructed. An important pre­requisite is having a decision-theoretical connection between design and risk manage­ment that always should permeate geotechnical design and construction. The presented research is based on the results from a research project funded by the Rock Engineering Research Foundation (BeFo) that was finalized in January 2019.

  • 8. Wei, Y.
    et al.
    Liu, Wei
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings.
    Xue, Y.
    Zhai, Z.
    Chen, Q.
    Zhang, T.
    Integrated inverse design of ventilation for an aircraft cabin2019In: E3S Web of Conferences, EDP Sciences , 2019Conference paper (Refereed)
    Abstract [en]

    Cabin ventilation is crucial for maintaining thermal comfort and air quality for passengers and crew. The genetic algorithm, proper orthogonal decomposition (POD), and adjoint method have been proposed to inversely design the cabin ventilation. However, each method has its cons and pros. This paper proposed to integrate the above three methods in cascades. The genetic algorithm was applied first in the first stage to roughly circumscribe the ranges of design parameters. Then POD was applied in the next stage to further narrow the ranges and estimate the optimal parametric sets for each design criterion. The estimated optimal design from POD was supplied to the adjoint method for fine tuning. The air-supply parameters of a five-row aircraft cabin were inversely designed to achieve the minimum absolute value of the predicted mean vote (PMV) and the minimum averaged mean age of air. The results showed that the integrated method was able to improve the design stage by stage. The integrated method has superior advantages to assure the optimal design while minimizing the computing expense.

  • 9.
    Lövqvist, Lisa
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE), Architecture, Architectural Technologies. KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Modeling the evolution of winter damage in an asphalt concrete microstructure2019Conference paper (Refereed)
    Abstract [en]

    Winter damage in asphalt pavements is a complex phenomenon which may cause pothole formation, dislodging of stones and structural layer separation. In order to reduce the winter damage, knowledge about the process in both the pavement and on a microstructural level is required. This paper focuses on modeling the process of damage evolution on a microstructural level in order to identify and understand the different phenomena influencing the degradation process. In this paper the evolution of winter damage in an asphalt concrete microstructure was modeled throughout the course of two winter seasons. The simulations include freezing and thawing cycles as well as additional damage originating from snow plows, both based on real weather data from Luleå in the north of Sweden. The results show a large increase of damage in both the mastic and the aggregate-mastic interface, and thereby also vertical displacement of the top surface, after the first freeze-thaw cycle. During the following freeze-thaw cycles the mastic damage continuous to increase but with a decreasing rate while the damage in the aggregate-mastic interface is only affected by the manually added damage from the snow plow. These results indicate a need to include the growth of -and emergence of new air voids in the model as well as an investigation of the actual behavior and influence of the damage evolution in the interface regions.

  • 10.
    Hellgren, Rikard
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Malm, Richard
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Eriksson, Daniel
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Modelling of the ice load on a Swedish concrete dam using semi-empirical models based on Canadian ice load measurements2019In: Sustainable and Safe Dams Around the World / [ed] Jean-Pierre Tournier, Tony Bennett & Johanne Bibeau, 2019, Vol. 2, p. 3068-3080Conference paper (Refereed)
    Abstract [en]

    In cold regions where the water surface of a river or lake freezes during the winter, concrete dams may be subjected to a pressure load from the ice sheet. This pressure load may constitute a large portion of the total horizontal load acting on a small dam. From a dam safety perspective, it is important to determine the design value of the ice load. In February 2016, a prototype of an ice load panel was installed on a Swedish concrete dam. The 1x3m2 panel measures the ice pressure with three load cells. In this paper, the ice load measured on the Swedish dam is predicted using a Canadian empirical model, previously developed from a 9-year field program to estimate the ice loads caused by thermal effects and variation in water level. The predictions from the model could not accurately predict the measured ice loads. Since the current understanding of ice load is limited, it is not possible to determine whether the measurement, the model or both are inaccurate.

  • 11.
    Zou, Liangchao
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Håkansson, Ulf
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics. Skanska AB .
    Cvetkovic, Vladimir
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Non-Newtonian grout flow in single rough-walled rock fractures2019Conference paper (Refereed)
    Abstract [en]

    Modeling of cement grout flow in rock fractures plays an important role in the design of rock grouting. Cement grouts used in rock grouting practice are typical non-Newtonian fluids containing yield stress, and are often assumed as Bingham fluids. Natural rock fractures typically consist of rough surfaces. Therefore, in reality, rock grouting process actually involves non-Newtonian fluid flow in rough-walled fractures, which is rarely studied in the literature. In this work, we focus on the impact of surface roughness and present direct numerical simulations of non-Newtonian grouts flow in single rough-walled fractures, using a regularized method to approximate the yield-stress. The rough-walled rock fracture models are created from a laser-scanned surface of a granite rock sample, to represent realistic features of natural rock fractures. The numerical results generally show nonlinear behaviors of non-Newtonian fluid flow in rough-walled fractures. The surface roughness significantly reduces the effective transmissivity when Reynolds number is relatively large. The obtained result can be used for upscaling analysis in practice, in order to reduce the potential uncertainties caused by the surface roughness of the rock fractures.

    The full text will be freely available from 2020-01-01 23:22
  • 12.
    Karlsson, Freddie
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering. Department of Civil Engineering, KU Leuven, Leuven, Belgium.
    Maes, K.
    Lombaert, G.
    Online tracking of inputs, states and parameters of structural dynamic systems2019In: Life-Cycle Analysis and Assessment in Civil Engineering: Towards an Integrated Vision - Proceedings of the 6th International Symposium on Life-Cycle Civil Engineering, IALCCE 2018, CRC Press, 2019, p. 211-217Conference paper (Refereed)
    Abstract [en]

    This paper presents a novel filtering algorithm for joint input-state-parameter estimation. The algorithm is derived from an existing joint input-state estimation algorithm. In each step, the system model is linearized around the current state, yielding an algorithm which is similar to the Extended Kalman filter. It is shown that, in the application to linear structural dynamic systems, the analytical expressions for the Jacobian matrices involved in the linearization are readily available due to the choice of parametrization. The proposed methodology is verified by numerical simulations for a four story shear building.

  • 13. Leurent, F.
    et al.
    Li, S.
    Badia, Hugo
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Structural design of a hierarchical urban transit network integrating modal choice and environmental impacts2019In: 21st EURO Working Group on Transportation Meeting, EWGT 2018, 17th – 19th September 2018, Braunschweig, Germany, Elsevier, 2019, Vol. 37, p. 99-106Conference paper (Refereed)
    Abstract [en]

    The paper develops a structural model and a design methodology for transit system planning in an urban area. Transit "components" are modelled by subarea and by sub-mode in terms of line length, station spacing, and fleet size, in order to determine both quality of service and production costs. Roadway networks are modeled with a Macroscopic Fundamental Diagram that relates speed to network capacity and vehicle demand. Local and global environmental impacts are considered. Travel demand includes both mode-dependent users and mode-choosers able to adopt the mode that offers higher utility. The design methodology involves a mathematical program of welfare optimization with respect to transit factors and fares. Two definitions of welfare are given, one that takes into account only demand surplus and supply profit, the other including environmental impacts. An example of application to Greater Paris shows that there is room for system optimization under current subsidy conditions, and that the explicit inclusion of environmental impacts brings about a significant shift in the "optimal" policy package.

  • 14. Tondini, N.
    et al.
    Morbioli, A.
    Battini, Jean-Marc
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    A 2D beam element for the analysis of flexural buckling of steel structures at elevated temperatures2018In: Applications of Fire Engineering - Proceedings of the International Conference of Applications of Structural Fire Engineering, ASFE 2017, CRC Press/Balkema , 2018, p. 199-208Conference paper (Refereed)
    Abstract [en]

    The paper describes the development of a two-dimensional (2D) nonlinear beam finite element that includes advanced path-following capabilities for detecting bifurcation instability of steel elements subjected to fire loading. A co-rotational formulation was used for describing the beam kinematic. The degradation of the steel mechanical properties at high temperature according to the Eurocode 1993-1-2 was considered by integrating the material constitutive law based on a predetermined temperature field in the cross section. Advanced path-following methods were implemented to analyse the elastic-plastic post-buckling behaviour of compressed steel elements at high temperature without the need of introducing geometrical imperfections. To highlight the practical implications, a parametric analysis showed that the element could reproduce the EN1993-1-2 buckling curve. The obtained outcomes were validated against experimental and numerical data obtained with commercial software ABAQUS and SAFIR. 

  • 15.
    Lövqvist, Lisa
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE), Architecture, Architectural Technologies. KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    A Coupled Micromechanical Model of Frost Damage in Asphalt2018In: Transportation Research Board 97th Annual Meeting, Washington DC, January 7-11, 2018, 2018Conference paper (Refereed)
    Abstract [en]

    Frost damage in asphalt pavements is an important factor influencing the performance of the pavement. This type of damage occurs during freeze-thaw cycles when ice forms in the air voids, causing microstructural changes and degradation of material properties, thus affecting the performance of the pavement. It is therefore necessary to understand the process of frost damage in order to prevent it. However, experimental testing is often expensive and time consuming and only a limited number of numerical models dealing with the topic exist. In this work, a numerical micromechanical model has been developed that couple the diffusion of moisture in the asphalt to the damage occurring in a freezing and thawing environment. In this paper, the model is presented and applied on an asphalt microstructure obtained by x-ray scanning of a real asphalt sample. The effect of including frost damage is shown by comparing the behavior of a damaged microstructure to the behavior of an undamaged microstructure. It is revealed that the strength of the damaged microstructure reduces to about 50% of the strength of the undamaged microstructure. Furthermore, the coupling of the moisture content in the air voids to the expansion of the air voids is proved to be important since the assumption that all air voids are fully saturated overestimates the decrease in strength. The next step in this research will be to validate the model with laboratory data. A validated model can assist in improving the predictions of frost damage and help in developing better laboratory tests.

  • 16.
    Neves, Andreas C.
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Gonzalez, Ignacio
    Sweco AB, Stockholm, Sweden..
    Leander, John
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges. KTH Royal Inst Technol, Struct Engn & Bridges, Stockholm, Sweden..
    Karoumi, Raid
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    A New Approach to Damage Detection in Bridges Using Machine Learning2018In: EXPERIMENTAL VIBRATION ANALYSIS FOR CIVIL STRUCTURES: TESTING, SENSING, MONITORING, AND CONTROL / [ed] Conte, JP Astroza, R Benzoni, G Feltrin, G Loh, KJ Moaveni, B, SPRINGER INTERNATIONAL PUBLISHING AG , 2018, p. 73-84Conference paper (Refereed)
    Abstract [en]

    At the same time that civil engineering structures are increasing in number, size and longevity, there is a conforming increasing preoccupation regarding the monitoring and maintenance of such structures. In this sense the demand for new reliable Structural Health Monitoring systems and damage detection techniques is high. A model-free damage detection approach based on Machine Learning is presented in this paper. The method performs on the collected feature measurements on a railway bridge, which for this study were gathered in a numerical experiment using a three dimensional finite element model. The first step of the approach consists in collecting the dynamic response of the structure, simulated during the passage of a train over the bridge, in both the healthy and damage states of the structure. The next step consists in the design and unsupervised training of Artificial Neural Networks that use as input accelerations and axle loads and compute a novelty index, called prediction error, based on a novelty detection approach. The distribution of the obtained prediction errors is statistically evaluated by means of a Gaussian Process and, after this process, damage indexes can be defined. Finally, the efficiency of the method is assessed in terms of Type I (false positive) and Type II (false negative) errors using Receiver Operating Characteristic curves. The promising results obtained in the case study demonstrate the capability of the presented method.

  • 17.
    Sadrizadeh, Sasan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Fluid and Climate Technology.
    Stensson, Sofia
    Walker, Iain
    Marashian, Shahrzad
    Holmberg, Sture
    Airborne bacteria inactivation in a hospital ward by ultraviolet irradiation2018In: In: Proceedings of the 4th International Conference on building Energy & Environment (COBEE 2018). February 5-9 2018; Melbourne, Australia, 2018Conference paper (Refereed)
    Abstract [en]

    This study considers numerical modelling based on the Computational Fluid Dynamics technique for a hospital ward with an upper-room ultraviolet germicidal irradiation fixture. A two-bed hospital ward equipped with a ceiling-level low-velocity ventilation diffuser was considered. The airflow field was considered steady state and ultraviolet distribution was treated as a scalar flux. Different particle sizes were simulated representing the pathogenic contaminants released from patients’ breathing zones. The results confirm the effectiveness of ultraviolet germicidal irradiation. However, an optimization study should be performed to enhance the disinfection efficiency of the system. Ultraviolet germicidal irradiation is an effective technique for airborne bacteria inactivation which potentially can be used to prevent the spread of certain infectious diseases.

  • 18.
    Lundberg, Joacim
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials. VTI - Statens Väg- och Transportforskningsinstitut.
    Janhäll, Sara
    VTI - Statens Väg- och Transportforskningsinstitut.
    Gustafsson, Mats
    VTI - Statens Väg- och Transportforskningsinstitut.
    Erlingsson, Sigurdur
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering. VTI - Statens Väg- och Transportforskningsinstitut / Islands Universitet.
    Calibration of the Swedish Studded Tyre Abrasion Wear Prediction Model and the Implication for the NORTRIP Road Dust Emission Model2018In: Transportation Research Board 97th annual meeting, Washington, D.C., 2018Conference paper (Refereed)
    Abstract [en]

    An experimentally based prediction model of rut development due to studded tyres is available in 3 Sweden and which had been found to work well. However, since it has not been validated since 4 2007, during which traffic as well as road and tyre design have developed, the question has 5 arisen regarding the model’s current validity. Also, since the prediction model is used in the 6 NORTRIP (NOn-exhaust Road Traffic Induced Particle emission) emission model, a natural 7 question is how a change in the wear model will affect the emission model. In this paper, two 8 versions of the abrasion model are compared to measurements at several recently constructed 9 roads in Sweden to investigate the validity, while also proposing changes to allow for continued 10 use. In addition, the impact on NORTRIP is briefly investigated. The paper first describes the 11 abrasion models and their calibration, as well as the test sections for calibration. Both versions of 12 the model, as expected, overestimated the wear and an update was suggested. It was also found 13 that NORTRIP is indicatively affected by overestimating the contribution of pavement wear to 14 the emissions.

  • 19.
    Ríos Bayona, Francisco
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Stigsson, Martin
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure. SKB, Swedish Nuclear Fuel and Waste Management Co.
    Johansson, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Mas Ivars, Diego
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics. SKB, Swedish Nuclear Fuel and Waste Management Co.
    Comparison between shear strength based on Barton’s roughness profiles and equivalent synthetic profiles based on fractal theory2018In: 52nd U.S. Rock Mechanics/Geomechanics Symposium, American Rock Mechanics Association (ARMA) , 2018Conference paper (Refereed)
    Abstract [en]

    A comprehensive understanding of the shear strength and the mechanical behavior of rock joints is to some extent still missing today. Several attempts have been made to develop empirical and analytical shear strength criteria that explain this mechanism. One of the most important parameters governing the shear strength of rock fractures is the surface roughness, which is generally determined using the Joint Roughness Coefficient (JRC). This parameter is often determined subjectively in the field by comparison with 10 predefined roughness profiles. Recent studies indicate that surface roughness can be accurately represented by using fractal analysis. The aim of this study is to perform a first attempt to investigate the mechanical equivalence in terms of the peak shear strength between synthetic rock fractures, where the surface roughness has been generated using fractal theory, and standard roughness profiles from Barton and Choubey, 1977, using the particle flow code PFC2D. The results from the numerical shear tests under constant normal load (CNL) are compared with the predicted peak shear strength using Barton’s criterion and a back-calculation of the JRC value is carried out.

  • 20.
    Frolovskaia, A. , V
    et al.
    Russia.
    Deordiev, S. , V
    Russia.
    Falk, Andreas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials. KTH Royal Inst Technol, SE-10044 Stockholm, Sweden..
    Klinduh, N. Y.
    Russia.
    Terehova, I. I.
    Russia.
    Experience of light thin-walled structures improvement in construction2018In: 6TH INTERNATIONAL CONFERENCE ON MECHATRONICS AND CONTROL ENGINEERING (ICMCE 2017), IOP PUBLISHING LTD , 2018, article id UNSP 012004Conference paper (Refereed)
    Abstract [en]

    The authors on the basis of practical experience have analyzed low-rise construction with the use of energy-saving technologies. Characteristic features of possible variants of frame construction are looked at and described. The relevance of the paper consists in the improvement of the building frame design solution based on the analysis and elimination of disadvantages taking into account consumers' point of view.

  • 21. Alsved, Malin
    et al.
    Wang, Cong
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Fluid and Climate Technology.
    Civilis, Anette
    Sadrizadeh, Sasan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Fluid and Climate Technology.
    Ekolind, Peter
    Skredsvik, Henrik
    Höjerback, Peter
    Jakobsson, Jonas
    Löndahl, Jakob
    Experimental and computational evaluation of airborne bacteria in hospital operating rooms with high airflows2018In: Proceedings of The 5th Working & Indoor Aerosols Conference 18-20 April 2018; Cassino, Italy, 2018Conference paper (Refereed)
    Abstract [en]

    Post-operative infections after surgery can be decreased by the use of efficient ventilation with clean air. In this study, we investigated three types of operating room ventilation: turbulent mixed airflow(TMA), laminar airflow (LAF) and a new type of ventilation named temperature controlled airflow(TcAF). Measurements of airborne bacteria were made during surgery and compared with values calculated by computational fluid dynamics (CFD). The results show that LAF and TcAF are most efficient in removing bacteria around the patient. With LAF, there are large differences in bacterial loads, depending on location in the room.

  • 22.
    Lövqvist, Lisa
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE), Architecture, Architectural Technologies. KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Freeze-thaw damage in asphalt: a set of simplified simulations2018In: Proceedings of Canadian Technical Asphalt Association 63rd Annual Conference / [ed] Stephen Goodman, 2018Conference paper (Refereed)
    Abstract [en]

    Winter damage in pavements, such as potholes, dislodging of stones and structural layer separation, occurs during and after winter seasons. This damage is caused by several processes, such as freezing and thawing action, moisture accumulation, traffic loads and winter maintenance actions, which combined makes winter damage a highly complex phenomenon. To better understand this process and, in the future, being able to predict the damage propagation by modeling, this paper discusses the possibility to separate these actions and phenomena into different cases. The focus in this paper is on the freezing -and thawing damage and how it is affected by different environmental conditions, inspired by real weather data from the City of Luleå in the north of Sweden. To investigate this, a microscale model is utilized. The results from the simulations show an increasing adhesive damage with the number of freeze-thaw cycles while the cohesive damage in the viscoelastic mastic increases is the most severe for a period with several days of freezing temperatures. A discussion of how the separation of winter damage into different cases will contribute to the ultimate goal of a multiscale model is also included.

  • 23.
    Andersson, Andreas
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Lind Östlund, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Mahir, Ülker-Kaustell
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Battini, Jean-Marc
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Karoumi, Raid
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Full-Scale Dynamic Testing of a Railway Bridge Using a Hydraulic Exciter2018In: EXPERIMENTAL VIBRATION ANALYSIS FOR CIVIL STRUCTURES: TESTING, SENSING, MONITORING, AND CONTROL / [ed] Conte, JP Astroza, R Benzoni, G Feltrin, G Loh, KJ Moaveni, B, SPRINGER INTERNATIONAL PUBLISHING AG , 2018, p. 354-363Conference paper (Refereed)
    Abstract [en]

    This paper presents a full-scale dynamic testing on a simply supported railway bridge with integrated end-shields, by using a hydraulic exciter. Experimental frequency response functions are determined based on load controlled frequency sweeps. Apart from accurate estimates of natural frequencies, damping and mode shapes, the experimental testing also gives valuable information about the dynamic characteristics at resonance and amplitude dependent nonlinearities. Numerical models are used to simulate the dynamic response from passing trains which is compared to experimental testing of similar train passages. The results show that the bridge deck is partially constrained due to the interaction between the end-shields and the wing walls with the surrounding soil. Measurements at the supports also show that the flexibility of the foundation needs to be accounted for. An updated numerical model is able to accurately predict the response from passing trains. The response is lower than that predicted from the initial simulations and the bridge will fulfil the design requirements regarding vertical deck acceleration.

  • 24.
    Eriksson, Daniel
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Gasch, Tobias
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Influence of air voids in multiphase modelling for service life prediction of partially saturated concrete2018In: Computational Modelling of Concrete Structures / [ed] Günther Meschke, Bernhard Pichler, Jan G. Rots, London, UK: CRC Press, 2018, p. 317-326Conference paper (Refereed)
    Abstract [en]

    The purpose of this study is to show the influence and significance of including water filling of air pores when studying moisture conditions in concrete structures cast with air-entrained concrete and in contact with free water. Especially if the aim is to assess the risk for frost damages in different regions of the structure, based on a critical degree of saturation, in order to ultimately perform a service life prediction. A hygro-thermo-mechanical multiphase model that includes the effect of water filling in air pores, recently presented by the authors, is briefly described and applied in two numerical examples. The results show moisture distributions that would not be possible to capture without the air pore filling included in the model. More importantly, the general shape of these distributions complies well with measured distributions in real concrete structures as well as with distributions obtained in laboratory measurements.

  • 25.
    Ghafoori Roozbahany, Ehsan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Partl, Manfred
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Guarin, Alvaro
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Influence of layer thickness on the flow of asphalt under simulated compaction2018In: Bearing Capacity of Roads, Railways and Airfields - Proceedings of the 10th International Conference on the Bearing Capacity of Roads, Railways and Airfields, BCRRA 2017, CRC Press/Balkema , 2018, p. 1435-1441Conference paper (Refereed)
    Abstract [en]

    Compaction is one of the most important phases in the life cycle of asphalt pavements and has therefore been a hot subject of research for a long time. However, despite of valuable research efforts on this topic, a remarkable gap between laboratory and field measurements still remains. Moreover, whereas most of the experimental methods are carried out on compacted pavement material, methods for evaluating compactability of asphalt mixtures for increasing the fundamental knowledge about internal movements within the asphalt during compaction are only scarce. Hence, in this study, a recently developed tool for simulating the compaction process with respect to the particle flow, i.e. Compaction Flow Test (CFT), was used along with simultaneous X-ray imaging for investigating the impact of thickness changes on two different asphalt mixture structures in terms of the compaction effort as well as flow pattern differences. The results of the investigation provided reasonably useful input for building up a better understanding of the behavior of mixtures under compaction loads. This method was able to successfully reveal the differences of the structural rearrangements within the asphalt mixtures for three different lift thicknesses. It also helped to explain some of the previous research studies results in a more comprehensive way. The achievements of this study may serve for developing an in-site evaluating test method for assessing compactability of asphalt mixtures before placing them on the roads.

  • 26.
    Wang, Cong
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Fluid and Climate Technology.
    Sadrizadeh, Sasan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Fluid and Climate Technology.
    Holmberg, Sture
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Fluid and Climate Technology.
    Influence of the shape of surgical lamps on the airflow and particle distribution in operating rooms2018In: Proceedings of Roomvent & Ventilation 2018. June 02-05, 2018; Espoo, Finland, 2018Conference paper (Refereed)
    Abstract [en]

    Operating room ventilation plays a significant role in reducing bacteria carrying particles concentration and preventing post-operative infections. The ventilation airflow may be disturbed by objects and heat loads and their effectiveness in reducing bacteria concentration can be compromised. Surgical lamps are one of the major disturbances in an operating room. This study numerically investigated the influence of lamp shapes on airflow patterns and dispersion of airborne bacteria.

    Two different shapes of lamps were studied: a closed-shape and an open-shape lamp. The simulation was performed based on the physical configuration of two operating rooms ventilated respectively by laminar airflow and temperature controlled airflow. Results show that the closed-shape lamp severely obstructs the airflow and results in high bacteria concentration in the laminar airflow, whereas the open-shape lamp has a negligible impact on the particle dispersion. The temperature controlled airflow is less sensitive to obstructions and maintains a clean surgical site with both types of lamps.

  • 27.
    Partl, Manfred
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Introduction2018In: RILEM State-of-the-Art Reports, Springer Netherlands , 2018, p. 1-14Conference paper (Refereed)
    Abstract [en]

    An overview on the background and motivation for this report on the achievements of the technical committee RILEM TC 237-SIB on Testing and Characterization of Sustainable Innovative Bituminous Materials and Systems is presented, together with a short summary on the scope of this voluntary international team effort. Challenges and key research paths towards modern “green” asphalt pavements are addressed, focusing on general aspects associated with the increasing variety of approaches and their implication on testing and characterization of innovative asphalt pavement materials. As example for the complexity of the experimental challenges and the potential necessity to break free from traditional testing patterns, selected specific aspects of reinforced asphalt pavements are considered and discussed. It is emphasized that testing must be consistent with the purpose of the reinforcement, answering the key questions in what respect, under what conditions and in what loading direction reinforcement should be achieved and tested. This “garbage-in-garbage-out” awareness is also valid for all other fields dealing with testing and characterization of innovative bituminous materials and systems, of course. 

  • 28.
    Ansell, Anders
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Nordström, Erik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures. Sweco Energuide, Hydro Power & Dams, Stockholm, Sweden.
    Guarin, Alvaro
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Laboratory investigation of steel fibre reinforced sprayed concrete using a computed tomography method2018In: Eight International Symposium on SPRAYED CONCRETE - Modern Use of Wet Mix Sprayed Concrete for Underground Support, 2018, p. 24-38Conference paper (Refereed)
    Abstract [en]

    A laboratory method for investigation of cored samples of steel fibre reinforced sprayed concrete (shotcrete) is described. A pilot study on computed tomography (CT) has been conducted, with focus on how the technique can be used for non-destructive testing where the cores remain intact after scanning and evaluation. The CT method require advanced integrated equipment for X-ray scanning and image detection, together with a computerized visualization system that can reproduce a threedimensional virtual, transparent model of the studied object. The method is well suited to describe orientation and distribution of steel fibres within the concrete. Interfaces between rock-concrete and concrete-concrete, between layers of differentsequences ofspraying, can also be identified. The results from the CT investigations can be presented as qualitative data that in 3D shows locations of steel fibres, aggregates, etc., and also as quantitative data showing relative distributions of cement paste, aggregates, steel fibres and voids, which is here demonstrated by a selection of examples. The method is well suited for practical analysis of sprayed concrete in situ specimens and it is recommended that it is established as a standard method for special inspections and performance evaluation of rock support in tunnels and subspace structures.

  • 29. Koháni, M.
    et al.
    Czimmermann, P.
    Váňa, M.
    Cebecauer, Matej
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport Planning, Economics and Engineering.
    Buzna, Ľ.
    Location-scheduling optimization problem to design private charging infrastructure for electric vehicles2018In: 6th International Conference on Operations Research and Enterprise Systems, ICORES 2017, Springer, 2018, p. 151-169Conference paper (Refereed)
    Abstract [en]

    We propose optimization model to design a charging infrastructure for a fleet of electric vehicles. Applicable examples include a fleet of vans used in the city logistics, a fleet of taxicabs or a fleet of shared vehicles operating in urban areas. Fleet operator is wishing to replace vehicles equipped with an internal combustion engine with fully electric vehicles. To eliminate interaction with other electric vehicles it is required to design a private network of charging stations that is specifically adjusted to the fleet operation. First, to derive a suitable set of candidate locations from GPS data, we propose a practical procedure where the outcomes can be simply controlled by setting few parameter values. Second, we formulate a mathematical model that combines location and scheduling decisions to ensure that requirements of vehicles can be satisfied. We validate the applicability of our approach by applying it to data characterizing a large taxicab fleet operating in the city of Stockholm. The model assumes that all vehicles posses complete information about all other vehicles. To study the role of available information, we evaluate the resulting designs considering the coordinated charging when vehicle drivers, for example, reveal to each other departure times, and the uncoordinated charging when vehicle drivers know only actual occupation of charging points. Our results indicate that this approach can be used to estimate the minimal requirements to set up the charging infrastructure.

  • 30.
    Zou, Liangchao
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Håkansson, Ulf
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Cvetkovic, Vladimir
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Modeling of rock grouting in saturated variable aperture fractures2018In: Proceedings of Bergdagarna 2018., 2018, p. 79-87, article id 10Conference paper (Refereed)
    Abstract [en]

    Modeling and analysis of cement grouts flow in rock fractures is important in the design, execution and monitoring of grouting in fractured rocks. At present, modeling of rock grouting mainly relies on analytical models, e.g., the real time grouting control (RTGC) method. In the RTGC method, it is assumed that the rock fractures are consisting of smooth parallel plates or disks and water flow is neglected. However, in reality, the natural rock fractures are commonly consisting of complex rough-walled surfaces and are filled with groundwater; therefore, grouting is actually a multiphase (non-Newtonian grouts and groundwater) flow process in rough-walled rock fractures with variable apertures. In this study, we present an efficient one-dimensional (1D) numerical model for modeling of rock grouting in a single rock fracture with consideration of multiphase flow and variable apertures. It is assumed that the cement grouts are Bingham fluids and that the analytical solution for flowrate with a given pressure gradient in a pair of smooth parallel plates is locally applicable. A time-dependent advection equation is used to describe the interface (between the grout and groundwater) propagation. A finite element method (FEM) code is developed to iteratively solve the mass balance and the interface advection equations. The numerical simulations are compared with the RTGC method. It generally shows that water flow significantly affect grouts penetration in the fracture, especially for the grouts with relatively lower viscosity. The variable aperture significantly postpones the penetration process compared with that of constant aperture. This numerical model is able to describe more realistic physical processes and geometry conditions in rock grouting, which can be readily used in practice to reduce the potential uncertainties in application of simplified analytical models.

  • 31.
    Sjölander, Andreas
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Rikard, Hellgren
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Ansell, Anders
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Modelling aspects to predict failure of a bolt-anchored fibre reinforced shotcrete lining2018In: 8th International Symposium on Sprayed Concrete: Modern Use of Wet Mix Sprayed Concrete for Undergro­und Support / [ed] Thomas Beck, Synnove A. Myren, Siri Engen, Trondheim, 2018, p. 278-292Conference paper (Refereed)
    Abstract [en]

     Tunnels in hard and jointed rock are normally excavated with an arch shape to enable the rock to carry itself. The arch effect depends on the stability of individual blocks and too high or too low horizontal stresses could cause blocks to be pushed out or to fall down. To prevent this, systematic rock bolting in combination with fibre reinforced sprayed concrete (FRSC) is commonly used to support the rock. To understand the failure mechanism of the lining when subjected to the load from one block is therefore important for the design. In this paper, the three main failure mechanisms for a rock support shotcrete lining has been identified as failure in the fibre reinforced concrete, bond failure between shotcrete and rock or failure of rock bolts. For each of the failure modes, a short review of numerical methods is presented followed by a selection of a preferred modelling approach. The selected methods are then verified against experimental results from the literature. The selected methods all shows good agreements with tests and demonstrates the ability to simulate each failure mode one by one.

  • 32.
    Ulker-Kaustell, Mahir
    et al.
    Tyrens AB, Stockholm, Sweden..
    Boschmonar, Gabriel F.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Isusi, Pablo B.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Trillkott, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Kullberg, Claes
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Karoumi, Raid
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Modelling of Pot Bearings - A Preliminary Study2018In: EXPERIMENTAL VIBRATION ANALYSIS FOR CIVIL STRUCTURES: TESTING, SENSING, MONITORING, AND CONTROL / [ed] Conte, JP Astroza, R Benzoni, G Feltrin, G Loh, KJ Moaveni, B, SPRINGER INTERNATIONAL PUBLISHING AG , 2018, p. 343-353Conference paper (Refereed)
    Abstract [en]

    Previous research indicates that roller and pot bearings may give rise to considerable non-linear effects in certain bridges. These effects appear as variations in natural frequency, mode shape and modal damping ratio, depending on the amplitude of vibration. At small amplitudes of vibration, it seems reasonable to assume that the rolling or sliding mechanism is inactive, thus yielding a stiffer structure and no additional dissipation of energy due to friction. At slightly larger amplitudes of vibration, although still remaining small with respect to geometrical non-linearity, the rolling or sliding mechanism activates, whereby the corresponding constraints are relieved. At the same time, because of the rolling or sliding friction, a certain amount of energy dissipates to the surroundings. In order to improve our understanding of these mechanisms and their practical implications, a preliminary experimental study has been performed with the aim of developing a simple model of these mechanisms, which can be included in theoretical models of bridges and other structures. In this paper, we give a short description of the outcome of our laboratory tests and the status of our model development process.

  • 33. Aggestam, E.
    et al.
    Nielsen, J. C. O.
    Andersson, Andreas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges. Swedish Transport Administration, Solna, SE-171 54, Sweden.
    Li, M.
    Multi-objective design optimisation of transition zones between different railway track forms2018In: Proceedings of the 11th International Conference on Contact Mechanics and Wear of Rail/wheel Systems, CM 2018, TU Delft , 2018, p. 1-6Conference paper (Refereed)
    Abstract [en]

    The vertical dynamic interaction between vehicle and railway track is simulated in the time domain using an extended state space vector approach. The track model includes a transition zone between slab track on a bridge and ballasted track on an embankment. By considering a multi-objective optimisation problem, solved using a genetic algorithm, selected vehicle and track responses are simultaneously minimised by optimising the distributions of rail pad stiffness and sleeper spacing in the transition zone. It is shown that the magnitudes of the maximum dynamic loads in the optimised transition zone can be reduced to be similar as the magnitudes far away from the transition zone.

  • 34.
    Vieira, Tiago
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials. VTI.
    Sandberg, Ulf
    VTI.
    Negative Texture, Positive for the Environment: Results of Horizontal Grinding of Asphalt Pavements2018Conference paper (Refereed)
    Abstract [en]

    A pavement surface having its texture deflections mostly directed downwards is said to have a “negative texture” and is expected to result in positive tire/road noise and rolling resistance properties. Negative textures are typical of porous asphalt pavements, but another way to achieve this is to grind-off the top of the asperities of a rough-textured surface. This paper explores the application of grinding pavement texture by tools operating in the horizontal plane (not to be confused with common “diamond grinding” which is made by tools operating in the vertical plane) on a number of asphalt pavements in Sweden, including porous asphalt and stone matrix asphalt. Noise measurements with the Close Proximity method were carried out to evaluate the different acoustical performance of the ground and the original surfaces. In most cases, also tire/road rolling resistance was measured. Texture and wet friction measurements were carried out to characterize how the grinding operation changed the surface texture. It was demonstrated that the grinding treatment led to a more negatively skewed surface texture, resulting in an A-weighted noise reduction up to 3 dB, while rolling resistance coefficients were reduced by up to 15 %. It is concluded that horizontal grinding indeed creates more “negative textures”, which results in improved noise and rolling resistance properties without sacrificing friction, though with limited longevity.

  • 35.
    Gonzalez, I.
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Khouri, Elisa
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Gentile, C.
    Karoumi, Raid
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Novel AI-based railway SHM, its behaviour on simulated data versus field deployment2018In: Proceedings of the 7th Asia-Pacific Workshop on Structural Health Monitoring, APWSHM 2018, NDT.net , 2018, p. 802-807Conference paper (Refereed)
    Abstract [en]

    A new damage detection method for railway bridges is presented. The proposed method uses raw acceleration data, avoiding the difficult step of designing a-priori a damage sensitive feature and leaving that task to the powerful pattern-recognition capacity of Artificial Intelligence, in particular an Artificial Neural Networks (ANN). The proposed method is applied to data from a numerical experiment and a field deployment and demonstrates good novelty detection capabilities in both cases. Closer examination of the results reveals, however, that the features automatically extracted by the ANN are qualitatively different in the two case studies. The numerical data, obtained by simulating moving point forces, is dominated by the modal behaviour of the structure and, consequently, whatever feature the ANN learns to evaluate it must be based on that modal information. The data measured in the field deployment is dominated by non-modal vibration (vibrations induced by rail-roughness, sleeper-distance and train-bridge interactions), which are of higher frequency than the modal data. Experiments with low- And high-pass filtered real data are performed to discern if the ANN extract features from the modal data (low-frequency), other high-frequency phenomena or a mix of both. These reveal that it is mainly the high-frequency data that informs the ANN novelty detection. The fact that the damage detection of the proposed algorithm is based mainly the high-frequency content of the input signals raises important questions about the validity/efficacy of numerical validations of this type of damage detection methods (and of modal-based approaches in general). These are normally confined to modalsimulations of moving point forces and thus only contain modal data, which seems to be of lesser importance when a machine learning approach is used. 

  • 36.
    Wang, Cong
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Fluid and Climate Technology.
    Sadrizadeh, Sasan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Fluid and Climate Technology.
    Numerical Assessment of a Novel Ventilation Strategy for Operating Rooms in Comparison with Turbulent Mixing and Laminar Air Flow2018In: Proceedings of The 15th Conference of the International Society of Indoor Air Quality & Climate (ISIAQ). July 22-27, 2018; Philadelphia, PA, USA, 2018Conference paper (Refereed)
    Abstract [en]

    Infectious airborne particles can cause surgical site infections (SSIs). SSIs cause substantially increased morbidity and mortality as well as patients’ sufferings. A well-functioning ventila-tion system in an operating room (OR) plays an essential role in the prevention of SSIs. In this study, we applied Computational Fluid Dynamics (CFD) to evaluate the performance of a novel OR ventilation strategy – temperature controlled airflow (TAF) against two widely used OR ventilation systems: laminar airflow (LAF) and turbulent mixing airflow (TMA). The performance was measured in terms of airborne bacteria concentration. Simulation results confirmed the superiority of LAF and TAF to TMA in providing high air cleanliness and also showed that TAF can serve as an efficient alternative to LAF.

  • 37.
    Hong, Beichuan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Ma, Xiaoliang
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Path optimization for a wheel loader considering construction site terrain2018In: 2018 IEEE Intelligent Vehicles Symposium (IV), Changshu, Suzhou, China, 26-30 June 2018, Changshu, China: IEEE, 2018, p. 2098-2103Conference paper (Refereed)
    Abstract [en]

    Wheel loader is one of the most widely used heavy-duty vehicles for transporting building materials in construction site. Improvement of its efficiency is important for sustainable transport and construction operations. This paper proposes a path optimization approach that allows us to plan loader trajectory and corresponding vehicle motions in construction site when the topological relief information is available. Vehicle dynamics is modeled for 3D motions considering the power balance of vehicle propulsion. The path planning problem is then formulated using a framework of constrained optimal control where vehicle dynamics is incorporated as system constraints. In order to solve the problem, a discrete search method is developed based on the principle of dynamic programming (DP), in which the states of the forward and backward movement paths of wheel loader are explored in parallel. A numerical study is then presented to demonstrate the application of the proposed approach for optimizing the loader path using terrain information.

  • 38.
    Tympakianaki, Athina
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport Planning, Economics and Engineering.
    Koutsopoulos, Haris N.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport Planning, Economics and Engineering. Department of Civil and Environmental Engineering, Northeastern University, Boston, MA 02115, United States.
    Jenelius, Erik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport Planning, Economics and Engineering.
    Robust SPSA algorithms for dynamic OD matrix estimation2018In: The 9th International Conference on Ambient Systems, Networks and Technologies (ANT 2018) / The 8th International Conference on Sustainable Energy Information Technology (SEIT-2018) / Affiliated WorkshopsThe 9th International Conference on Ambient Systems, Networks and Technologies (ANT 2018) / The 8th International Conference on Sustainable Energy Information Technology (SEIT-2018) / Affiliated Workshops, Elsevier, 2018, Vol. 130, p. 57-64Conference paper (Refereed)
    Abstract [en]

    The Simultaneous Perturbation Stochastic Approximation (SPSA) algorithm has been used for solving the off-line dynamic origin-destination (OD) estimation problem. While the algorithm can be used with very general formulations of the problem, it can also be unstable. The paper proposes methods and evaluates their effectiveness in improving the SPSA performance at two levels: a) scaling the step size and using a hybrid gradient estimation; and b) proposing alternative clustering strategies to be used with the c-SPSA version of the algorithm, where OD flows are estimated in clusters. The proposed enhancements are evaluated through simulation experiments on a real network.

  • 39. Darcel, C.
    et al.
    Davy, P.
    Le Goc, R.
    Ivars, Diego Mas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Rock mass effective properties from a DFN approach2018In: 2nd International Discrete Fracture Network Engineering Conference, DFNE 2018, American Rock Mechanics Association (ARMA) , 2018Conference paper (Refereed)
    Abstract [en]

    Rock mass mechanical properties are strongly controlled by the fractures they contain. Their determination raises strong issues for many rock-engineering applications, like underground repository safety assessment, support design, slope stability or mine caving. To compensate the impossibility to perform direct in-situ measures of these properties at appropriate scales, empirical approaches classically aim to determine the rock mass equivalent properties from simple indicators. Here we propose an approach based on the complete representation of the rock mass as an intact rock with a population of discrete fractures through it (the Discrete Fracture Network). The core of the approach is the definition, at the rock mass scale, of the deformation induced by each fracture locally, including the fracture mechanical and geometrical parameters, the remote stress conditions and the interactions with the rest of the fracture population. Depending on the conditions, the resulting scaling and anisotropic effects can be critical. The method is applied to the Forsmark site in Sweden. We show that two main scaling regimes occur, where the shift from the one to the other is controlled by the ratio between the intact rock modulus, the typical fracture stiffness and the DFN size distribution. Beyond the scaling issue we quantify the resulting level of anisotropy. 

  • 40.
    Wersäll, Carl
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Nordfelt, Ingmar
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Roller compaction of rock-fill with automatic frequency control2018In: Proceedings of the Anniversary Symposium – 40 Years of Roller Integrated Continuous Compaction Control (CCC), 2018Conference paper (Refereed)
  • 41.
    Leander, John
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Karoumi, Raid
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Rohner, Christian
    Uppsala universitet.
    Höglund, Joel
    SICS RISE.
    Wirström, Niklas
    SICS RISE.
    Rosengren, Peter
    CNet Svenska AB.
    Eriksson, Daniel
    CNet Svenska AB.
    Smart condition assessment, surveillance and management of critical bridges2018Conference paper (Refereed)
    Abstract [sv]

    Bridges with critical roles in heavily loaded transport infrastructures often need to be kept in service despiteknown damage and deficiencies. Closing or limiting the traffic on a bridge, leading to traffic diversions, issometimes not a feasible option. The current paper describes an approach for securing the functionalityand the safety of critical bridges by using an innovative smart system for monitoring and conditionassessment. It builds on the use of wireless sensor networks, advanced assessment methods, and cloudbased services for storage and distribution of results. This is an ongoing research project and the progressso far is presented in this paper. A case study of the Old Lidingö Bridge in Stockholm, Sweden, is used todemonstrate the approach. The monitoring system installed, devices for energy harvesting, and methodsfor condition assessment are presented. Some preliminary results on the condition of the bridge are alsopresented.

  • 42.
    Johansson, Fredrik
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Westberg Wilde, Marie
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Krounis, Alexandra
    KTH, School of Architecture and the Built Environment (ABE).
    Spross, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Ríos Bayona, Francisco
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Some recent developments in reliability based slidingstability assessments for concrete dams2018In: 26th International Congress on Large Dams, 2018, CRC Press/Balkema , 2018, p. 1277-1294Conference paper (Refereed)
    Abstract [en]

    In this paper, a reliability based framework for the assessment of sliding stability for concrete dams was presented. The framework consists of several parts based on the Probabilistic model code for concrete dams developed by Westberg-Wilde and Johansson and includes guidelines on how reliability based sliding stability assessment should be performed, together with recent work by Krounis et al. how to account for partially bonded interfaces. In the proposed framework, the assessments start with performing preliminary calculations using a priori assumptions on parameters included in the analysis. If cost-benefit analyses show that further analyses could be beneficial, investigations are undertaken on relevant parameters in the failure modes. The results from the investigations are used to update the calculations in the assessment and decisions on stability enhancing measures are undertaken if necessary. In the presented example the preliminary sliding stability analysis of the interface, before testing was performed, showed a reliability index of 4.91, indicating an unacceptable failure probability of the dam without any testing. Taking into account the information obtained from testing the basic friction angle of the interface increased the reliability index from 4.91 to 7.24, clearly showing the gain of including test results in the assessment. When the influence of cohesion was accounted for a reliability index of 6.49 was obtained, which shows that cohesion can give a potential gain to the stability, even though it in this case still is lower than the gain from updating the basic friction angle. When both limit states of the interface were considered as a system the reliability index increased to 8.1.

  • 43.
    Johansson, Fredrik
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Westberg Wilde, Marie
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics. ÅF.
    Krounis, Alexandra
    ÅF.
    Spross, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Ríos Bayona, Francisco
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Some recent developments in reliability-based assessments for concrete dams2018In: Proceedings of 26th Congress on large dams, 2018, Vol. Q101-R78, p. 1277-1294Conference paper (Refereed)
    Abstract [en]

    In this paper, a reliability based framework for the assessment of sliding stability for concrete dams was presented. The framework consists of several parts based on the Probabilistic model code for concrete dams developed by Westberg-Wilde and Johansson and includes guidelines on how reliability based sliding stability assessment should be performed, together with recent work by Krounis et al. how to account for partially bonded interfaces. In the proposed framework, the assessments start with performing preliminary calculations using a priori assumptions on parameters included in the analysis. If cost–benefit analyses show that further analyses could be beneficial, investigations are undertaken on relevant parameters in the failure modes. The results from the investigations are used to update the calculations in the assessment and decisions on stability enhancing measures are undertaken if necessary. In the presented example the preliminary sliding stability analysis of the interface, before testing was performed, showed a reliability index of 4.91, indicating an unacceptable failure probability of the dam without any testing. Taking into account the information obtained from testing the basic friction angle of the interface increased the reliability index from 4.91 to 7.24, clearly showing the gain of including test results in the assessment. When the influence of cohesion was accounted for a reliability index of 6.49 was obtained, which shows that cohesion can give a potential gain to the stability, even though it in this case still is lower than the gain from updating the basic friction angle. When both limit states of the interface were considered as a system the reliability index increased to 8.1.

  • 44.
    Cebecauer, Matej
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport planning.
    Jenelius, Erik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport planning.
    Burghout, Wilco
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport planning.
    Spatio-Temporal Partitioning of Large Urban Networks for Travel Time Prediction2018In: 2018 21ST INTERNATIONAL CONFERENCE ON INTELLIGENT TRANSPORTATION SYSTEMS (ITSC), IEEE , 2018, p. 1390-1395Conference paper (Refereed)
    Abstract [en]

    The paper explores the potential of spatiotemporal network partitioning for travel time prediction accuracy and computational costs in the context of large-scale urban road networks (including motorways/freeways, arterials and urban streets). Forecasting in this context is challenging due to the complexity, heterogeneity, noisy data, unexpected events and the size of the traffic network. The proposed spatio-temporal network partitioning methodology is versatile, and can be applied for any source of travel time data and multivariate travel time prediction method. A case study of Stockholm, Sweden considers a network exceeding 11,000 links and uses taxi probe data as the source of travel times data. To predict the travel times the Probabilistic Principal Component Analysis (PPCA) is used. Results show that the spatio-temporal network partitioning provides a more appropriate bias-variance tradeoff, and that prediction accuracy and computational costs are improved by considering the proper number of clusters towards robust large-scale travel time prediction.

  • 45.
    Abbaszadeh Shahri, Abbas
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Spross, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Johansson, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Storskalig kartering av skredbenägenhet i västra Götaland med artificiell intelligens2018Conference paper (Other academic)
  • 46.
    Amer, Wadi
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Lars, Pettersson
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Structural response of a high profile arch flexible culvert in sloping terrain using finite element modeling2018Conference paper (Refereed)
    Abstract [en]

    Flexible culverts are generally considered cost-effective structures for their simplicity in construction and the short time involved in the erection process. This has constantly motivated practitioners to explore the different areas of application including their performance in sloping environment. Yet, the complex nature of the interaction between the soil and steel materials marks a challenge, where the performance of these structures is fundamentally influenced by the quality of the backfill soil and its configuration around the conduit/arch. Surface slopes may affect the structural response by inducing an asymmetrical soil support and an unbalanced earth loading.

    The use of numerical simulation is utilized to provide insights about the performance of flexible culvert in sloping environment, where a case study of a high profile arch is investigated under different construction schemes. The paper focuses mainly on predicting the structural behavior of soil loading effects. The study includes the influence of different slopes in combination with various depths of soil cover.

    The results enabled to realize the importance of soil configuration around the steel arch and its influence on the structural response. While the presence of surface slopes emphasizes the susceptibility of flexible culverts with low depths of soil cover, higher covers may help in reducing the effect of steep slopes. Sectional forces were found to increase with the increase of surface slopes. The study also highlighted recent research efforts on the topic and briefly discussed some design implications when building flexible culverts in sloping terrain.

  • 47.
    Wadi, Amer
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Pettersson, Lars
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Structural response of a high profile arch flexible culvert in sloping terrain using finite element modeling2018Conference paper (Refereed)
    Abstract [en]

    Flexible culverts are generally considered cost-effective structures for their simplicity in construction and the short time involved in the erection process. This has constantly motivated practitioners to explore the different areas of application including their performance in sloping environment. Yet, the complex nature of the interaction between the soil and steel materials marks a challenge, where the performance of these structures is fundamentally influenced by the quality of the backfill soil and its configuration around the conduit/arch. Surface slopes may affect the structural response by inducing an asymmetrical soil support and an unbalanced earth loading.

    The use of numerical simulation is utilized to provide insights about the performance of flexible culvert in sloping environment, where a case study of a high profile arch is investigated under different construction schemes. The paper focuses mainly on predicting the structural behavior of soil loading effects. The study includes the influence of different slopes in combination with various depths of soil cover.

    The results enabled to realize the importance of soil configuration around the steel arch and its influence on the structural response. While the presence of surface slopes emphasizes the susceptibility of flexible culverts with low depths of soil cover, higher covers may help in reducing the effect of steep slopes. Sectional forces were found to increase with the increase of surface slopes. The study also highlighted recent research efforts on the topic and briefly discussed some design implications when building flexible culverts in sloping terrain.

  • 48.
    Döse, Magnus
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures. RISE CBI BETONGINSTITUTET AB.
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures. KTH.
    Supplementary Cementitious Materials and Additives – Effective Measures to Hinder Radon in Concrete2018Conference paper (Refereed)
    Abstract [en]

    The second largest cause of lung cancer is related to radon (222Rn) and its progenies in our environment. Building materials, such as concrete, contribute to the production of radon gas through the natural decay of 238U from its constituents. The Swedish Cement and Concrete Research Institute (CBI) has examined ten different concrete recipes containing an additive or Supplementary Cementious Material (SCM), such as fly ash, slag or silica and combinations thereof. The SCM´s were added in small to moderate portions and substituted the reference Portland cement (OPC). The inputs of an additive as well as a supplementary cementitious material were made as a mean to investigate their potential influence on the radon exhalation rates of the concrete as well as the radon gas diffusion length (L) that could be expected from the different recipes. Measurements were performed with an ATMOS 33 ionizing pulsation chamber. The results indicate a reduction of the exhalation rate by approximately 10-55 % depending on recipe at an RH of 75 %. The diffusion coefficients, corrected for background subtraction vary in the interval 1.1 x 10-10 – 7.6 x 10-12 m2/s. The diffusion lengths vary between 2 and 9 mm. In the case where the largest reduction of the exhalation rate is achieved, this roughly correspond to >2 mSv per year decrease in effective dose to a human. Consequently, using an additive or a SCM, as part of the mix, would be an option to effectively lower the radon gas exhalation in their initial stage of production. Secondly, the use of additives and SCM´s will contribute to a lower environmental impact (CO2).

  • 49.
    Leander, John
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Karoumi, Raid
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    The value of monitoring on the service life prediction of a critical steel bridge2018In: Life Cycle Analysis and Assessment in Civil Engineering: Towards an Integrated Vision: Proceedings of the Sixth International Symposium on Life-Cycle Civil Engineering (IALCCE 2018), 28-31 October 2018, Ghent, Belgium, 2018, p. 2121-2128Conference paper (Refereed)
    Abstract [en]

    This paper is focused on the service life prediction of steel bridges subjected to a combination of corrosion and fatigue. Both deterioration mechanisms are dubious to handle in theoretical assessments due to large uncertainties, on the action effect side and the resistance side. A reliability-based assessment in combination with updating considering monitoring and inspections provide an approach to reduce the uncertainties. To evaluate what assessment actions to engage, this approach has been combined with Bayesian decision theory which provides a rational basis to evaluate the value of information (VoI). The Old Liding\"{o} Bridge in Sweden is used as a case study to demonstrate the reliability-based approach. This bridge is subjected to severe corrosion and has been deemed unfit for service. However, it provides the only link to the island Liding\"{o} for the local tram and pedestrians why the bridge owner has decided to keep it in service until a new bridge is in place. To secure the safety of the bridge, recurrent inspections are conducted and discovered defects are repaired immediately. A system for continuous monitoring of critical parts was installed during the spring 2017. The bridge, the approach for assessment, and the procedure for evaluating the VoI are presented in the paper.

  • 50.
    Sadrizadeh, Sasan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Fluid and Climate Technology.
    Rojas, Gabriel
    Clark, Jordan
    Walker, Iain
    Sherman, Max
    Validated numerical simulations of wall-mounted kitchen range hood pollutant capture and sensitivity tests to inform development of a method of test2018In: Proceedings of The 15th Conference of the International Society of Indoor Air Quality & Climate (ISIAQ). July 22-27, 2018; Philadelphia, PA, USA, 2018Conference paper (Refereed)
    Abstract [en]

    Cooking is one of the most important sources of indoor air pollution in most residences. Until recently, range hoods used to remove pollutants generated during cooking were rated by flow rate and noise criteria only in the United States. We sought to help inform a standardized method of test for range hoods which relates rating more directly to pollutant removal performance. To this end, a numerical model is first validated and then used to assess the effects of several parameters on apparent capture efficiency for a wall-mounted hood. Results show that some seemingly benign variables, such as the size of the test room, have large effects on simulated capture efficiency.

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