| 20331. |
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| 20332. |
- Riml, Joakim, 1979-
(författare)
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Solute Transport Across Scales : Time Series Analyses of Water Quality Responses to Quantify Retention and Attenuation Mechanisms in Watersheds
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The intra-continental movement of waterborne contaminants is governed by the distribution of solute load in the landscape along with the characteristics and distribution of the hydrological pathways that transport the solutes. An understanding of the processes affecting the transport and fate of the contaminants is crucial for assessments of solute concentrations and their environmental effect on downstream recipients. Elevated concentration of nutrients and the presence of anthropogenic substances, such as pharmaceutical residues, are two examples of the current problems related to hydrological transport. The overall objective of this thesis is to increase the mechanistic understanding of the governing hydrological transport processes and their links to geomorphological and biogeochemical retention and attenuation processes. Specifically, this study aims to quantify the processes governing the transport and fate of waterborne contaminants on the point, stream reach, and watershed scales by evaluating time series obtained from stream tracer tests and water quality monitoring data. The process quantification was achieved by deriving formal expressions for the key transport characteristics, such as the central temporal moments of a unit solute response function and the spectral scaling function for time series of solute responses, which attributes the solute response in the Laplace and Fourier domains to the governing processes and spatial regions within the watershed. The results demonstrate that in addition to the hydrological and biogeochemical processes, the distribution of the load in the landscape and the geomorphological properties in terms of the distribution of transport pathway distances have defined effects on the solute response. Furthermore, the spatial variability between and along the transport pathways significantly affect the solute response. The results indicate that environments with high retention and attenuation intensity, such as stream-reaches with pronounced hyporheic zones, may often dominate the solute flux in the watershed effluent, especially for reactive solutes. The mechanistic-based framework along with the evaluation methodologies presented within this study describes how the results can be generalized in terms of model parameters that reflect the hydrology, geomorphology and biogeochemistry in the studied area. This procedure is demonstrated by the parameterization of a compartment-in-series model for phosphorous transport.
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| 20333. |
- Rimsjö, Åsa
(författare)
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Environmental Assessment of Building Products and Components in a Service Life Perspective
- 2003
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents a survey of different tools, used byenvironmental consultants in Sweden, for their recommendationsof building products and components in different constructionprojects. The goal was to identify possible improvements of thetools so that life cycle methodology could be used to a largerextent than today. This thesis also presents a general methodfor multi-criteria assessment. The purpose of this generalmethod was to show how assessment of environmental impacts,cost and prediction of service life have to be combined for acomprehensive view over all the criteria that influencedecision-making in different construction projects.The evaluation of the present role of environmentalconsultants in the building process in Sweden and their toolsis based on a literature study together with interviews.Advantages and disadvantages of the different tools fordecision-making have been identified. It was found that thereare many improvements to be made, for example, concerningbuilding product declarations. The declarations have to containmore quantitative data and the guidelines have to be furtherdeveloped to secure equivalence in product comparisons. Thestudy showed that an environmental consultant seldom makes anelaborate assessment of aspects other than environmentalimpacts. Others, for example, the client or contractor,consider aspects of economy and technical functionality.However, there is a need of a more comprehensive view wherecosts and technical functionality are included in theassessment together with environmental concerns. If differentaspects are treated separately there is a risk ofsuboptimisations. This need has been identified by for exampleconsultants and the commission of the Swedish government and isoften emphasised by the building material industry.In Life Cycle Assessment (LCA) the functionality, as well asthe time of use should be reflected in the definition thefunctional unit of the study. Calculations of Life Cycle Cost(LCC) also include the time aspect and compared systems shouldfulfil the same requirements of functionality. Therefore, it isof obvious interest to find a method that brings together LCA,LCC and service life planning (with estimations of servicelives). The presented method of multi-criteria assessment is toa large extent considered to be of practical use for practisingconsultants in their recommendations of the preferable choice,as soon as a pedagogical interface has been developed. Inaddition, a simplified LCA technique has to be used, where somesystemlimits and assumptions are pre-defined. A multi-criteriaassessment approach is one step ahead to fulfil therequirements of the authorities and the society. Themulti-criteria approach also helps the building sector to worktowards the goal of increased environmental concern in thesector and the overarching goal of an environmental sustainablesociety.Key words:life cycle assessment, LCA, environmentaldeclarations, building product declarations, environmentalconsultants, tool for decision-making, service life planning,estimation of service life, the factor method, multi-criteriaassessment
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| 20334. |
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| 20335. |
- Rinehart, Aidan, 1987-, et al.
(författare)
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Experimental and numerical investigation of turbulent boundary layer over an anisotropic porous plate.
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- We investigate how a porous substrate with streamwise preferential permeability modifies the near wall flow structures and turbulent statistics. The study provides particle image velocimetry (PIV) measurements made in a turbulent boundary layer over 3D printed porous tiles. The same idealized porous surface in an open channel flow is modeled within a direct numerical simulation. The combined approach allows complete flow details to be analyzed as well as insight into the real world application of such surfaces. The turbulent statistics of the experimental and numerical approaches show a reduction in the peak streamwise fluctuations and enhanced wall normal fluctuations. We show a negligible drag change for the experiment work and slight drag increase for the simulation. Kelvin Helmholtz vortices are observed confirming earlier predictions as a source of performance degradation.
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| 20336. |
- Rinehart, Aidan, 1987-
(författare)
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Numerical and experimental investigations of fluid-surface interaction
- 2021
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Fluid-structure interactions play a central role in an overwhelming number of physical phenomena. All fluid dynamic students are familiar with the common assumption of a "smooth boundary". While this assumption often is enough to provide a high level understanding of the dynamics and physics at hand in practice this is not true. Much of the detail and the unique phenomena can be traced back to surface properties that deviate from this elementary assumption. In this work we investigate three problems all motivated by the existence of non-smooth surfaces. The first paper considers how inhomogeneous surfaces can generate a lift force for lubricated contacts. This work showcases how subtle changes to surface texture or chemistry modeled by a slip length can invoke non-trivial forces. These forces result in striking particle trajectories not possible in the presence of a smooth no-slip wall. The next work focuses on porous surfaces. Often the geometry of surfaces in nature and industry are complex covering a wide range of length scales. Resolving all the scales of motion arising from fluid interaction with such surfaces are computationally expensive. Effective equations are often applied to reduce the cost of such simulations. The Brinkman equation is one common model choice for free-fluid and porous surface interface. Despite the common application of the Brinkman equation, fundamental questions about what the effective viscosity should be remain open. We compare pore-scale Stokes flow solutions to the Brinkman model for several porous surfaces. This study provides a scaling for the effective viscosity as well as error quantification of the Brinkman model. Lastly, we investigate how porous surfaces modify a turbulent boundary layer. Streamwise preferential porous surfaces have recently been suggested as a surface modification that has the potential to reduce drag. We compare particle image velocimetry measurements with direct numerical simulations focusing on the near wall features that are modified from the canonical smooth wall case. We present some preliminary turbulent statistics and flow visualizations in the current report.
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| 20337. |
- Rinehart, Aidan, et al.
(författare)
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Validation of Brinkman equation for a steady shear flow over porous media.
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The Brinkman equation has found great popularity in modeling the interfacial flow between a free fluid and a porous medium. However, there is a significant debate in what the Brinkman viscosity should be as well as the physical applicability of the model. Here, we perform a numerical study of the Brinkman equation's capability as an effective model of the flow in a porous media with regular structures when subjected to an overlying steady shear flow. By adjusting the Brinkman viscosity, the effective solution is matched to the volume-averaged pore-scale flow field obtained from direct numerical simulations.As previous studies, we find that the Brinkman viscosity can obtain values much smaller and larger than the free fluid viscosity. By computing the L2 norm error of the velocity profiles, we provide a quantitative evaluation of the accuracy of the Brinkman equation over various isotropic and anisotropic regular porous geometries. For a range of solid volume fractions, a significant improvement of the accuracy of the effective model is obtained when the porous medium is decomposed into two domains with different Brinkman viscosities. Given the solid volume fraction of structured porous medium, our work can be used to estimate the modeling error induced by the single- and two-domain Brinkman system.
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| 20338. |
- Ringenson, Tina, et al.
(författare)
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Digitalization and Environmental Aims in Municipalities
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Many municipalities express a wish to use digital technologies to reach environmental aims. However, there is still a need for better understandings of how this should practically be done, both among municipalities and among ICT developers. We have used workshops and literature studies to formulate technological abilities of digitalization. We use two EU directives that are relevant for municipal environmental goals, and combine the activities that these directives indicate, in order to formulate practical implementations of digital technology to help these activities and reach the directives’ goals. We suggest that this method can be used for any municipal goal, as follows: 1. Identify the objective (in our case set by the EU-directives); 2. Identify what activities these points will require or generate; 3a. From a municipal viewpoint: Based on the results of 1 and 2, formulate and structure ideas of how digitalization can support the objectives, and how those ideas can be implemented; 3b. From a provider´s viewpoint: Investigate what digital solutions supporting 1 and 2 exist, or how existing services can be tweaked to support the objectives, and explore how new digital solutions supporting 1 and 2 can be developed.
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| 20339. |
- Ringenson, Tina, 1988-
(författare)
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How municipalities can work with digitalisation for environmental aims
- 2018
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Humanity is facing big environmental challenges. Apart from the climate changes, there is also an ongoing depletion of the natural resources necessary for our survival in general, and for highly electronics-dependant lifestyles especially. At the same time, both urbanisation and digitalisation are progressing at a rapid pace. Digitalisation holds a potential to decrease environmental impact from cities and urban lifestyles, and many cities want to increase their use of digital technologies and services. This is often at least partially motivated by environmental concerns. In these cases, it is often the municipality that is responsible for strategies and support of increased digitalisation.This dissertation places itself in the Smart Sustainable City field, but more specifically aims to support municipalities’ work with digitalisation for environmental goals. The results are structured around three parts. The first part accounts for six cities’ promising digital solutions with possible environmental benefits, and of possible digital tools to support two EU directives that can affect municipalities’ environmental work. The second part suggests how municipalities can work with digitalisation for environmental goals, and especially stresses evaluation and strategic investments. The third part looks at possible long-term societal changes in relation to digitalisation, and the risks with a city depending on electronics: It is important that a city can remain adequately functional, even in the case of a short- or long term shortage of resources and/or energy.Finally, I discuss some of the uncertainties in digitalisation for environmental goals. There are uncertainties regarding digitalisation’s actual effects, which can make it harder to know what investments to make. Implementing digital technologies for municipal aims often demands cooperation between actors with different interests, but if the municipality relates its decision to environmental goals, it facilitates demanding that digital services and tools have environmental benefits.
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| 20340. |
- Ringenson, Tina, 1988-
(författare)
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Mobilising digitalisation to serve environmental goals
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Human development is currently leading to destruction of the stability of the earth system upon which we depend for our survival. In other words, it is unsustainable. At the same time, urbanisation and digitalisation are progressing at a rapid pace. Digital technologies have a potential to decrease environmental impact from cities and urban lifestyles. Transport and mobility is an important part of urban life, and it has been suggested that digital technology can improve urban transport performance in both accessibility and sustainability. Mobility as a Service (MaaS) is a relatively new concept for provision of mobility services through a digital platform, sometimes together with digital accessibility services that lower the need to travel (Accessibility as a Service – AaaS). It has been suggested that MaaS could offer a real alternative to the privately owned car and lead to more sustainable mobility. However, its real effects in practice are still not well known.This thesis aims to create knowledge to guide public and private actors in developing digital technologies and using digitalisation to support environmental goals, especially regarding urban mobility. The results are structured around three parts. The first part explores strategies and digital services for municipalities that want to use digital technology to support environmental goals. The second part presents requirements for MaaS and AaaS to support environmental goals for urban mobility. To do so, they should reduce travelling overall and reduce environmental impact per kilometre travelled through enabling better modes of transport and lower vehicle emissions. It also suggests that a functional physical infrastructure for public transport and bicycling is important if MaaS are to support environmental goals. The third part identifies important knowledge gaps to explore, if digital services are to support environmental goals. The relationship between digital services, urban form, and sustainability implications is brought up as an important subject for future research, as well as how to ensure that MaaS fulfil the previously identified requirements.Finally, I discuss how to ensure that digital services and MaaS serve environmental goals. There are sometimes grave uncertainties regarding the real effects of various services. Although this makes future effects difficult to predict, it also suggests that investments need to be done strategically, and that data of effects need to be carefully collected and evaluated. Public and private actors both have responsibilities to ensure that digital services fulfil environmental goals. However, it is important not to only look at how to solve specific problems today. To support urban sustainability, we need to think about what kinds of cities we want. We do not have to focus digital services on streamlined, seamless and instant access to things no matter where they are. They can also support urban lifestyles of less focus on physical ownership and daily travelling, and more on positive experiences of sustainable modes of travel and of the local community.
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