Machine Control System Modeling and Design For Incremental Profile Forming of Metal Tubular Structures

Today, manufacturers require specialized machinery to produce various metal tubular designs for aeronautical and automotive applications. In an effort to reduce machine and tooling redesign with every unique tubular cross-sectional profile, the Incremental Profile Forming (IPF) process was created a few years ago at the Technical University of Dortmund, Germany. The innovative IPF machine includes eight degrees of freedom of motion which enable flexibility in manufacturing, such that a single machine can produce various metal tube profiles. However, control of machine motions alone has not resulted in precision of the manufactured part geometry. The lack of precision using the current process calls for extending control of the manufacturing process beyond machine control, and for better utilization of machine control to support such extension. The purpose of this research is to investigate current control of machine motions used by the IPF machine, and identify ways to integrate machine control with process control to increase precision of the manufactured parts. Within this research, the current machine control systems used to govern the motions of the radial actuators used for tube forming were studied. Multiple experiments were conducted on the IPF machine to help validate system models and investigate system responses to various inputs and IPF processes. The gathered force, position, and structural measurements were analyzed to support the development of the motion control system models, as well as active stiffness control and online identification methods. Extensions of the machine control to include active stiffness control and online-identification of process parameters are two different control methods that were investigated to help improve precision in tube manufacture. The potential of these two methods to better accommodate various process disturbances and process characteristics was examined. Research results include complete models of the commercially available motors and radial actuators that are used by the motion control systems. These models were used to modify active stiffness control and online identification capabilities. This work establishes the basis for, and feasibility of, controller modeling for current and potential future functions performed by the IPF machine. Successful integration of new control methods in the IPF machine will enable effective use of its flexibility, while improving its accuracy in metal tube manufacturing.National Science FoundationNo embargoAcademic Major: Mechanical Engineerin

Application of a constitutive model to extensional and shear rheology of polystyrene carbon nanofiber composites

This research focuses on improving an existing constitutive model to predict the rheology of polystyrene-carbon nanofiber (CNF) composites and examining the differences between two nanocomposite preparation techniques and two types of nanofibers. The constitutive model is a set of equations adapted to predict the dynamic behavior of polymer nanocomposites and the orientation evolution of nanofibers. The equations in the model are functions of time, type of flow, stress, deformation, nanofiber orientation, and flow history due to the polymer's viscoelasticity. Important parameters in the model include: polymer relaxation time, polymer viscosity, mobility factor, polymer-particle interaction, particle-particle interaction, and aspect ratio. Three flow fields were examined: small-amplitude oscillatory shear, transient shear, and transient extensional flows. The two preparation techniques examined are commonly used in preparing polymer composites: melt-blending and solvent casting. The nanofibers examined were as received from the manufacturer with some undergoing additional high-heat treating. This research resulted in the development of an accurate model for the composites for all three flow fields. Values of parameters in the model have given insight into the physical behavior of the composite due to polymer-particle and particle-particle interactions and due to agglomeration. An accurate model of a polymer-CNF composite would be beneficial to industry, as the manufacturing processes such as extrusion, flow through dies, or spraying alter the orientation and consequently the mechanical, electrical, thermal, and optical properties of the composite. This model can provide a way to understand these effects would improve the optimization of properties.No embargoAcademic Major: Chemical Engineerin

Comparison of PFAS soil remediation alternatives at a civilian airport using cost-benefit analysis

Contamination of soil and water systems by per-and polyfluoroalkyl substances (PFAS) due to uncontrolled use of aqueous film-forming foams (AFFFs) at firefighting training sites at civilian and military airports is a universal issue and can lead to significant human health and environmental impacts. Remediation of these sites is often complex but necessary to alleviate the PFAS burden and minimise the risks of exposure by eliminating the hotspot/source from which the PFAS spreads. This study presents a probabilistic cost-benefit analysis (CBA) for evaluating PFAS reme-diation alternatives, which includes monetisation of both direct costs and benefits as well as externalities. The method is applied for a case study to compare five remediation alternatives for managing PFAS contaminated soil at Stockholm Arlanda Airport in Sweden. The social profitability, or the net present value (NPV), of each remediation alternative was calculated in comparison to two reference alternatives - 'total excavation' of the site (Alt 0) or 'do nothing'. Sensitivity analyses and model scenarios were tested to account for uncertainties, including small or large PFAS spreading and simulating different values for the magnitude of annual avoided cost of inaction (i.e., aggregate benefit) from PFAS re-mediation. In comparison to total excavation, four of the five studied remediation alternatives resulted in a positive mean NPV. Excavation and stabilization/solidification of the hotspot on-site combined with stabilization using acti-vated carbon for the rest of site (Alt 2) had the highest NPV for both spreading scenarios, i.e., Alt 2 was the most so-cially profitable alternative. Simulations of the annual avoided cost of inaction enabled estimation of the breakeven point at which a remediation alternative becomes socially profitable (NPV > 0) compared to 'do nothing'. Alt 2 had the lowest breakeven point: 7.5 and 5.75 millions of SEK/year for large and small spreading, respectively

Transforming brownfields into urban greenspaces: A working process for stakeholder analysis

Urban greenspaces (UGS) provide a range of ecosystem services and are instrumental in ensuring the liveability of cities. Whilst incorporating UGS in increasingly denser cities is a challenge to planners, brownfields form a latent resource with the potential of being converted into UGS. Transformation of brownfields to greenspaces, however, requires engagement of a variety of stakeholders, from providers to users. The overall aim of this study was to support effective and realistic realisations of UGS in the context of urban brownfields’ regeneration and stakeholder engagement. A working process was developed to: 1) integrate methods relevant for UGS realisation for a) identification and categorising of relevant stakeholders, b) mapping their interests and resources, c) identifying various challenges, and d) matching those challenges with the mapped resources over the timeline of UGS development; and 2) apply these methods to assess relevance and shortcomings. The methods were applied to a study site in Sweden, and data was collected using a questionnaire survey. The survey received 31 responses and the respondents’ comments indicated that the combination of several uses, especially integrated with an urban park, is preferable. Visualisation was an important component for data analysis: stakeholder categorisation was effectively visualised using a Venn diagram, and the needed mobilisation of resources among stakeholders to manage identified challenges was visualised using a timeline. The analysis demonstrates the need for collaboration between stakeholders to achieve an effective realisation of UGS and how multiple methods can be used in concert to map stakeholders, preferences, challenges, and resources for a particular site. The application at a study site provided site-specific data but the developed stakeholder categorisation, and the method for matching identified challenges with the stakeholders’ resources using a timeline, can be generalised to applications at other sites

Comparison of PFAS soil remediation alternatives at a civilian airport using cost-benefit analysis

Contamination of soil and water systems by per- and polyfluoroalkyl substances (PFAS) due to uncontrolled use of aqueous film-forming foams (AFFFs) at firefighting training sites at civilian and military airports is a universal issue and can lead to significant human health and environmental impacts. Remediation of these sites is often complex but necessary to alleviate the PFAS burden and minimise the risks of exposure by eliminating the hotspot/source from which the PFAS spreads. This study presents a probabilistic cost-benefit analysis (CBA) for evaluating PFAS remediation alternatives, which includes monetisation of both direct costs and benefits as well as externalities. The method is applied for a case study to compare five remediation alternatives for managing PFAS contaminated soil at Stockholm Arlanda Airport in Sweden. The social profitability, or the net present value (NPV), of each remediation alternative was calculated in comparison to two reference alternatives – ‘total excavation’ of the site (Alt 0) or ‘do nothing’. Sensitivity analyses and model scenarios were tested to account for uncertainties, including small or large PFAS spreading and simulating different values for the magnitude of annual avoided cost of inaction (i.e., aggregate benefit) from PFAS remediation. In comparison to total excavation, four of the five studied remediation alternatives resulted in a positive mean NPV. Excavation and stabilization/solidification of the hotspot on-site combined with stabilization using activated carbon for the rest of site (Alt 2) had the highest NPV for both spreading scenarios, i.e., Alt 2 was the most socially profitable alternative. Simulations of the annual avoided cost of inaction enabled estimation of the breakeven point at which a remediation alternative becomes socially profitable (NPV > 0) compared to ‘do nothing’. Alt 2 had the lowest breakeven point: 7.5 and 5.75 millions of SEK/year for large and small spreading, respectively

Enhancing ecosystem services at urban brownfield sites - What value does contaminated soil have in the built environment?

Urban environments are challenged with a plethora of wicked problems in the face of rapid urbanization and land use change, not least natural capital degradation and widespread land and water contamination. Brownfields, under-used sites with real or perceived contamination, are significant urban and peri-urban land resources which, with well-designed remediation and management strategies can address these concerns. Gentle remediation options (GRO) are scalable nature-based techniques which provide significant opportunities for multi-functionality: managing risks posed by contaminants and at the same time enhance ecosystem services (ES) by improving the soil ecosystem in a low-impact, cost-effective manner. GRO align with an increasing interest in taking a holistic view on soil and land management to protect and improve the soil ecosystem for direct human benefit in the form of ES as well as for its indirect, intrinsic value as a haven for biodiversity. This short review aims to present a synthesis of ideas to raise awareness for urban planners about GRO techniques as nature-based solutions which can promote green infrastructure in the urban environment

A risk management framework for Gentle Remediation Options (GRO)

Gentle Remediation Options (GRO) are remediation measures involving plants, fungi, bacteria, and soil amendments that can be applied to manage risks at contaminated sites. Several studies and decision-support tools promote the wider range of benefits provided by GRO, but there is still skepticism regarding GRO implementation. Key issues that need to be better communicated are the various risk mitigation mechanisms, the required risk reduction for an envisioned land use, and the time perspective associated with the risk mitigation mechanisms. To increase the viability and acceptance of GRO, the phytomanagement approach implies the combination of GRO with beneficial green land use, gradually reducing risks and restoring ecosystem services. To strengthen the decision basis for GRO implementation in practice, this paper proposes a framework for risk management and communication of GRO applications to support phytomanagement strategies at contaminated sites. The mapping of the risk mitigation mechanisms is done by an extensive literature review and the Swedish national soil guideline value model is used to derive the most relevant human health exposure pathways and ecological risks for generic green land use scenarios. Results indicate that most of the expected risk mitigation mechanisms are supported by literature, but that knowledge gaps still exist. The framework is demonstrated to support the identification of GRO options for the case study site given two envisioned land uses: biofuel park and allotment garden. A more easily understandable risk management framework, as proposed here, is expected to act as a communication tool to educate decision-makers, regulatory bodies and other stakeholders for better understanding of risk mitigation mechanisms and preliminary timeframes of various GRO, particularly in the early stages of a brownfield redevelopment project

The significance of planning and management of the subsurface to achieve sustainable cities

Introduction: The subsurface is the foundation upon which all cities rest. But the subsurface is not only a construction basis which provide physical space for infrastructure and the possibility to create a better surface living environment: the subsurface is a multifunctional natural resource. Apart from physical space, it provides water, energy, materials, habitats for ecosystems, support for surface life, and a repository for cultural heritage and geological archives. Currently, the subsurface is often utilised according to the “first-come-first-served” principle, which hinders possibilities to take strategic decisions on prioritisation and optimisation of competing subsurface uses, as well as fair inter- and intragenerational distribution of limited natural resources. A great disadvantage is the invisibility of the subsurface and consequently a lack of understanding of it as a multifunctional resource: the recently launched concept of geosystem services could help mitigate its underrating. Methods: In order to better acknowledge and lift forward the significance of the subsurface in achieving a sustainable future, the 17 SDGs are scrutinized in relation to the resources of subsurface, and specifically how better planning and management of the subsurface can contribute in achieving the goals. Results: Subsurface planning and management is relevant to at least seven (3, 6, 7, 9, 11, 12, 13) out of seventeen SDGs. Although the subsurface is not explicitly mentioned in the SDGs (except for aquifers), the subsurface can significantly contribute in achieving several of these goals. Conclusions: Sound planning and management of the subsurface can support the achievement of the mapped SDGs in various ways. The subsurface must be recognised as a precious and multifunctional resource which require careful planning and sensitive management in accordance with its potential and its value to society.Grant support: Swedish Research Council Formas (942-2016-50), Swedish Rock Engineering Research Foundation (BeFo 385), Swedish Institute Visby Programme (23887/2017)

Using soil function evaluation in multi-criteria decision analysis for sustainability appraisal of remediation alternatives

Soil contamination is one of the major threats constraining proper functioning of the soil and thus provision of ecosystem services. Remedial actions typically only address the chemical soil quality by reducing total contaminant concentrations to acceptable levels guided by land use. However, emerging regulatory requirements on soil protection demand a holistic view on soil assessment in remediation projects thus accounting for a variety of soil functions. Such a view would require not only that the contamination concentrations are assessed and attended to, but also that other aspects are taking into account, thus addressing also physical and biological as well as other chemical soil quality indicators (SQIs). This study outlines how soil function assessment can be a part of a holistic sustainability appraisal of remediation alternatives using multi-criteria decision analysis (MCDA). The paper presents a method for practitioners for evaluating the effects of remediation alternatives on selected ecological soil functions using a suggested minimum data set (MDS) containing physical, biological and chemical SQIs. The measured SQls are transformed into sub-scores by the use of scoring curves, which allows interpretation and the integration of soil quality data into the MCDA framework. The method is demonstrated at a study site (Marieberg, Sweden) and the results give an example of how soil analyses using the suggested MDS can be used for soil function assessment and subsequent input to the MCDA framework

Session summary - The accelerating need for Urban Green Spaces (UGS) in cities and how to best accommodate it

Urban Green Spaces (UGS) are vegetated open spaces that provide a multitude of ecological functions that are essential for the physical and mental well-being of the citizens as well as for the urban environment. However, land is an extremely competitive resource in cities that are struggling to sustain the ever-growing urban population and UGS are constantly under threat of urban encroachment. Even the well spread out cities are pressured to densify by the more commonplace ‘sustainable dense urban neighbourhood’ approach that in turn, increases the pressure on open spaces such as UGS. But UGS are lacking both by quantity and quality in most cities to support the need of the citizen. Their shortage and inadequacy of UGS were made obvious during the Covid-19 pandemic when the quarantine restricted the mobility of the urban populace and made UGS an essential, and often time, the only outdoor element in everyday city life. As well as lacking in quality and quantity, the pandemic and the resulting extended quarantine also pushed forward the inherent social issues with UGS; such as their unequal distribution, access, ongoing privatisation, ‘green gentrification, etc. The session focus was on the multifaceted challenge for UGS management and governance and how to accommodate the growing necessity of UGS in cities that are heightened in a world with Covid-19