Placemaking - a process that supports social sustainability in urban planning? : an investigation in theory and examples from Scandinavian practice

En hållbar utveckling är högt på agendan i dagens stadsplanering. I takt med den starka urbanisering som sker blir staden en allt viktigare arena för att hantera den sociala pelaren av en hållbar utveckling. Att människor är delaktiga och involverade i utvecklingen av sin omgivning är viktigt för social hållbarhet i stadsplanering. I ett sätt att involvera invånare i planeringen som sker av deras närmiljö har placemaking utvecklats som en filosofi och process för att skapa attraktiva platser som människor bryr sig om. Filosofin och processen bygger på delaktighet och involvering genom hela planeringsprocessen och anses därför lämplig för att hantera frågor som rör social hållbarhet. Placemaking har dock stött på kritik för att exempelvis bidra till gentrifiering när områden upprustas för att bli attraktiva. Syftet med arbetet är att utreda hur det egentligen ligger till. Har placemaking potential att användas för att skapa attraktiva platser och samtidigt främja en socialt hållbar utveckling? I en inledande litteraturstudie beskrivs begreppen placemaking samt social hållbarhet. Denna del följs av en översikt med kritik riktad mot placemaking. Genom intervjuer med involverade personer i de tre skandinaviska projekten With a heart for Arendal i Norge, Sønderparken i Danmark samt kortsiktiga experiment i Haninge kommun, undersöks placemaking i praktiken . Detta bidrar till en diskussion kring skillnader och likheter i filosofin och hur processen egentligen går till i praktiken gällande placemakings potential att användas i syfte att främja en socialt hållbar stadsutveckling. Arbetet kommer fram till att placemaking som filosofi har stor potential att hantera frågor som rör en socialt hållbar utveckling. Arbetet kommer också fram till att det finns kritiska punkter när filosofin implementeras i praktiken och att detta påverkar placemakings faktiska potential att främja en socialt hållbar utveckling. Att placemaking är ett otydligt begrepp med varierad definition och användning anses vara en avgörande faktor. I en skandinavisk kontext är problematiken densamma men de redan demokratiska planeringssystemen i Skandinavien anses utgöra en god grund för att den grad av medborgarmedverkan som placemaking förespråkar ska kunna utvecklas och fungera i syfte att främja en socialt hållbar stadsutveckling. Arbetet bidrar med en diskussion kring placemakings potential att användas för att främja en socialt hållbar stadsutveckling samt specifikt en fördjupning angående frågeställningen i skandinavisk kontext.A sustainable development is high on the agenda in today’s urban planning. While a strong urbanization is a fact, the city becomes an increasingly important arena to deal with the social pillar of a sustainable development. An important part of social sustainability in urban planning is inclusiveness and the ability to participate in the development of the environment. In an attempt to involve people in the planning of their everyday environment, the philosophy and process of placemaking has developed to create attractive places which people care about. The philosophy and process is based on community-led planning and aims for participation and involvement throughout the process. Placemaking can for this reason be seen to deal well with aspects of a socially sustainable urban development. Placemaking has, on the other hand, been criticized to lead to gentrification while areas are being developed to become more attractive. The aim with this work is to investigate what really is the case. Does placemaking have potential to be used in order to create attractive places while supporting a socially sustainable urban development? In an introducing study of literature placemaking and social sustainability are described. This is followed by an overview of critics of placemaking in relation to social sustainability. Through interviews with participants of the three Scandinavian placemakingprojects With a heart for Arendal and Levende Lokaler in Norway, Sønderparken in Denmark and short term experiments in the municipality of Haninge in Sweden, placemaking is in practice investigated. The projects contribute to a discussion of similarities and differences in the philosophy and how the process actually is used in practice regarding the potential of placemaking to be used in order to support a socially sustainable urban development. The study finds out that placemaking as a philosophy has big potential to deal with questions regarding social sustainability. The study also finds out that there are critical points when the philosophy is implemented in practice, which has an influence on the actual potential of placemaking to support social sustainability. The unclear definition and variated use of placemaking is claimed to be one important factor. In a Scandinavian context the same type of problems appear. The already democratic planning systems of Scandinavia is however seen to be a good basis for the amount of involvement the community-led process of placemaking is promoting. Placemaking is therefore seen to have potential to further be developed in order to support social sustainability in a Scandinavian context. The work contributes to discussions regarding placemaking and its potential to be used in order to support a socially sustainable urban development and is specifically contributing with a recess in a Scandinavian context

A zonal approach for estimating pressure ratio at compressor extreme off-design conditions

This is the author s version of a work that was accepted for publication in International Journal of Engine Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published as https://doi.org/10.1177/1468087418754899[EN] Zero-dimensional/one-dimensional computational fluid dynamics codes are used to simulate the performance of complete internal combustion engines. In such codes, the operation of a turbocharger compressor is usually addressed employing its performance map. However, simulation of engine transients may drive the compressor to work at operating conditions outside the region provided by the manufacturer map. Therefore, a method is required to extrapolate the performance map to extended off-design conditions. This work examines several extrapolating methods at the different off-design regions, namely, low-pressure ratio zone, low-speed zone and high-speed zone. The accuracy of the methods is assessed with the aid of compressor extreme off-design measurements. In this way, the best method is selected for each region and the manufacturer map is used in design conditions, resulting in a zonal extrapolating approach aiming to preserve accuracy. The transitions between extrapolated zones are corrected, avoiding discontinuities and instabilities.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Daniel Tari is partially supported through contract FPI-S2-2015-1095 of Programa de Apoyo para la Investigacion y Desarrollo (PAID) of Universitat Politecnica de Valencia.Galindo, J.; Navarro, R.; García-Cuevas González, LM.; Tarí, D.; Tartoussi, H.; Guilain, S. (2019). A zonal approach for estimating pressure ratio at compressor extreme off-design conditions. International Journal of Engine Research. 20(4):393-404. https://doi.org/10.1177/1468087418754899S393404204Mezher, H., Chalet, D., Migaud, J., Raimbault, V., & Chesse, P. (2014). Wave dynamics measurement and characterization of a charge air cooler at the intake of an internal combustion engine with integration into a nonlinear code. International Journal of Engine Research, 15(6), 664-683. doi:10.1177/1468087413513584Lavoie, G. A., Ortiz-Soto, E., Babajimopoulos, A., Martz, J. B., & Assanis, D. N. (2012). Thermodynamic sweet spot for high-efficiency, dilute, boosted gasoline engines. International Journal of Engine Research, 14(3), 260-278. doi:10.1177/1468087412455372Dolz, V., Novella, R., García, A., & Sánchez, J. (2012). HD Diesel engine equipped with a bottoming Rankine cycle as a waste heat recovery system. Part 1: Study and analysis of the waste heat energy. Applied Thermal Engineering, 36, 269-278. doi:10.1016/j.applthermaleng.2011.10.025Serrano, J. R., Dolz, V., Novella, R., & García, A. (2012). HD Diesel engine equipped with a bottoming Rankine cycle as a waste heat recovery system. Part 2: Evaluation of alternative solutions. Applied Thermal Engineering, 36, 279-287. doi:10.1016/j.applthermaleng.2011.10.024Bousquet, Y., Carbonneau, X., Dufour, G., Binder, N., & Trebinjac, I. (2014). Analysis of the Unsteady Flow Field in a Centrifugal Compressor from Peak Efficiency to Near Stall with Full-Annulus Simulations. International Journal of Rotating Machinery, 2014, 1-11. doi:10.1155/2014/729629Broatch, A., Galindo, J., Navarro, R., & García-Tíscar, J. (2016). Numerical and experimental analysis of automotive turbocharger compressor aeroacoustics at different operating conditions. International Journal of Heat and Fluid Flow, 61, 245-255. doi:10.1016/j.ijheatfluidflow.2016.04.003Semlitsch, B., & Mihăescu, M. (2016). Flow phenomena leading to surge in a centrifugal compressor. Energy, 103, 572-587. doi:10.1016/j.energy.2016.03.032Hung, K.-S., Chung, J.-C., Liu, C.-C., & Huang, J.-M. (2017). A study of off-design performance improvement for a centrifugal refrigerant compressor. Advances in Mechanical Engineering, 9(3), 168781401769622. doi:10.1177/1687814017696224Leufvén, O., & Eriksson, L. (2014). Measurement, analysis and modeling of centrifugal compressor flow for low pressure ratios. International Journal of Engine Research, 17(2), 153-168. doi:10.1177/1468087414562456Serrano, J. R., Tiseira, A., García-Cuevas, L. M., Inhestern, L. B., & Tartoussi, H. (2017). Radial turbine performance measurement under extreme off-design conditions. Energy, 125, 72-84. doi:10.1016/j.energy.2017.02.118Serrano, J. R., Olmeda, P., Tiseira, A., García-Cuevas, L. M., & Lefebvre, A. (2013). Theoretical and experimental study of mechanical losses in automotive turbochargers. Energy, 55, 888-898. doi:10.1016/j.energy.2013.04.042Galindo, J., Tiseira, A., Navarro, R., Tarí, D., & Meano, C. M. (2017). Effect of the inlet geometry on performance, surge margin and noise emission of an automotive turbocharger compressor. Applied Thermal Engineering, 110, 875-882. doi:10.1016/j.applthermaleng.2016.08.099Casey, M., & Robinson, C. (2012). A Method to Estimate the Performance Map of a Centrifugal Compressor Stage. Journal of Turbomachinery, 135(2). doi:10.1115/1.4006590Martin, G., Talon, V., Higelin, P., Charlet, A., & Caillol, C. (2009). Implementing Turbomachinery Physics into Data Map-Based Turbocharger Models. SAE International Journal of Engines, 2(1), 211-229. doi:10.4271/2009-01-0310Serrano, J. R., Olmeda, P., Arnau, F. J., Dombrovsky, A., & Smith, L. (2014). Analysis and Methodology to Characterize Heat Transfer Phenomena in Automotive Turbochargers. 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Modeling for control of centrifugal compressors

Downsizing and turbocharging of engines provide a way to meet increasing demands for efficiency and performance in the automotive industry. An engine design is a result of compromises, e.g. the selection of charging system, and the trend is to reduce these compromises by increasing system complexity. Models have come to play a central role to handle this rise in complexity, and are used for simulation, system optimization and control synthesis. The models should describe the entire operating range, be capable of extrapolation, be easily parameterizable, and wide cover a range of applications. A novel compressor model is developed which, in addition to the nominal operation, also covers surge, choke and operation at pressure ratios less than one. The model is based on data from more than 300 compressor maps, measurements from engine test stands, and a surge test stand. The general knowledge gained from the in-depth analysis is condensed in the model equations. The model can be automatically parametrized using a compressor map, is based on static functions for low computational cost, and is shown to extrapolate low speed compressor operation well. Furthermore, it is shown to be applicable to compressors of different size, ranging from small car applications to large heavy duty vehicles. Compressor restriction operation is modeled down to a standstill compressor, and shown to agree well with gas stand measurements. Further, the analysis contributes with new knowledge and models for choking pressure ratio and flow. A method to automatically determine a turbo map, when the turbo is installed on an engine in an engine test stand is developed. The method can be used to validate manufacturer maps or expand the region covered in a map. An analysis of the limits that an engine installation imposes on the reachable points in the compressor map is performed. The addition of a throttle before the compressor is suggested to increase the reachable map region, and an engine and test cell control structure that can be used to automate the measurements is proposed. Two methods that compensate for the deviation between measured and desired speeds, are proposed and investigated. A gas stand map is compared to the map generated in the engine test stand, and a generally good agreement results. An experimental analysis of the applicability of the commonly used correction factors, used for estimating compressor performance when the inlet conditions deviate from nominal, is performed. Correction factors are vital, to e.g. estimate turbocharger performance for driving at high altitude or to characterize second stage compressor performance, where the variations in inlet conditions are large. Measurements from an engine test stand and a gas stand show a small but clearly measurable trend, with decreasing compressor pressure ratio for decreasing compressor inlet pressure, for points with equal corrected shaft speed and corrected mass flow. A method that enables measurements to be analyzed with modified corrections is developed. As a result, an adjusted shaft speed correction quantity is proposed, incorporating also the inlet pressure in the shaft speed correction

Compressor Modeling for Control of Automotive Two Stage Turbochargers

There is a demand for increasing efficiency of automotive engines, and one way to achieve this is through downsizing and turbocharging. In the design compromises are made, for example the maximum power of the engine determines the size of the compressor, but since the compressor mass flow range is limited, this affects the torque for low engine speeds. A two stage system, with two different sized turbochargers, reduces this compromise, but the system complexity increases. To handle the complexity, models have come to play a central role where they aid engineers in the design. Models are used in simulation, for design optimization and also in the control synthesis. In all applications it is vital that the models have good descriptive capabilities for the entire operating range studied. A novel control oriented compressor model is developed, with good performance in the operating regions relevant for compressors in a two stage system. In addition to the nominal operating regime, also surge, choke and operation at pressure ratios less than unity, are modeled. The model structure can be automatically parametrized using a compressor map, and is based on static functions for low computational cost. A sensitivity analysis, isolating the important characteristics that influence surge transients in an engine is performed, and the gains of a novel surge controller are quantified. A compressor map is usually measured in a gas stand, that has different surrounding systems, compared to the application where the compressor is used. A method to automatically determine a turbo map, when the turbo is installed on an engine in an engine test stand is developed. The map can then be used to parametrize the developed compressor model, and effectively create a model parametrized for its intended application. An experimental analysis of the applicability of the commonly used correction factors, used for estimating compressor performance when the inlet conditions deviate from nominal, is presented. Correction factors are vital, to e.g. estimate turbocharger performance for driving at high altitude or to analyze second stage compressor performance, where the variations in inlet conditions are large. The experimental campaign uses measurements from an engine test cell and from a gas stand, and shows a small, but clearly measurable trend, with decreasing compressor pressure ratio for decreasing compressor inlet pressure, for points with equal corrected shaft speed and corrected mass flow. A method is developed, enabling measurements to be analyzed with modified corrections. An adjusted shaft speed correction quantity is proposed, incorporating also the inlet pressure in the shaft speed correction. A high altitude example is used to quantify the influence of the modified correction

Modeling for control of centrifugal compressors

Downsizing and turbocharging of engines provide a way to meet increasing demands for efficiency and performance in the automotive industry. An engine design is a result of compromises, e.g. the selection of charging system, and the trend is to reduce these compromises by increasing system complexity. Models have come to play a central role to handle this rise in complexity, and are used for simulation, system optimization and control synthesis. The models should describe the entire operating range, be capable of extrapolation, be easily parameterizable, and wide cover a range of applications. A novel compressor model is developed which, in addition to the nominal operation, also covers surge, choke and operation at pressure ratios less than one. The model is based on data from more than 300 compressor maps, measurements from engine test stands, and a surge test stand. The general knowledge gained from the in-depth analysis is condensed in the model equations. The model can be automatically parametrized using a compressor map, is based on static functions for low computational cost, and is shown to extrapolate low speed compressor operation well. Furthermore, it is shown to be applicable to compressors of different size, ranging from small car applications to large heavy duty vehicles. Compressor restriction operation is modeled down to a standstill compressor, and shown to agree well with gas stand measurements. Further, the analysis contributes with new knowledge and models for choking pressure ratio and flow. A method to automatically determine a turbo map, when the turbo is installed on an engine in an engine test stand is developed. The method can be used to validate manufacturer maps or expand the region covered in a map. An analysis of the limits that an engine installation imposes on the reachable points in the compressor map is performed. The addition of a throttle before the compressor is suggested to increase the reachable map region, and an engine and test cell control structure that can be used to automate the measurements is proposed. Two methods that compensate for the deviation between measured and desired speeds, are proposed and investigated. A gas stand map is compared to the map generated in the engine test stand, and a generally good agreement results. An experimental analysis of the applicability of the commonly used correction factors, used for estimating compressor performance when the inlet conditions deviate from nominal, is performed. Correction factors are vital, to e.g. estimate turbocharger performance for driving at high altitude or to characterize second stage compressor performance, where the variations in inlet conditions are large. Measurements from an engine test stand and a gas stand show a small but clearly measurable trend, with decreasing compressor pressure ratio for decreasing compressor inlet pressure, for points with equal corrected shaft speed and corrected mass flow. A method that enables measurements to be analyzed with modified corrections is developed. As a result, an adjusted shaft speed correction quantity is proposed, incorporating also the inlet pressure in the shaft speed correction