| 1. |
- Salmasi, Armin, 1983-
(författare)
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ICME guided study of mass transport in production and application of cemented carbides
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cemented carbides are metallic composites consisting of a WC hard phase and a ductile binder, usually Co-based, produced by powder metallurgy and sintering. Cemented carbides are an essential part of modern material and manufacturing processes. However, Co powder is classified as a carcinogenic material with serious health hazards, and most virgin Co reservoirs are located in conflict regions. In addition, there are monopolies in the market for pure tungsten. Therefore, reducing the consumption of cobalt or replacing it with other non-hazardous elements would increase the sustainability of cemented carbide production. Furthermore, advances in production technology can help overcome raw material limitations. One such advancement is non-homogeneous structures and properties for optimization of microstructure which is the topic of this thesis. Integrated computational materials engineering (ICME) and its complementary tools, calculation of phase diagram (CALPHAD), and ab-initio modeling are strong tools that bridge experimentation and modeling. In this thesis, a framework for the material design of non-homogeneous cemented carbides is proposed and tested using these computational tools. The workflow of the material design of non-homogeneous microstructure and properties were studied on different length scales. Atomistic modeling with density functional theory (DFT), ab-initio molecular dynamics (AIMD), and generalized hydrodynamics (GHD) were used to model the viscosity of liquid Co binder. In addition, the mobility of Ti and Fe in disordered BCC TiFe alloy was assessed using new experimental data from the diffusion couple experiments and an electron probe micro-analyzer (EPMA). These two studies were conducted to complete the data necessary to study cemented carbides’ processing and performance. The other studied phenomenon studied by experimentation and modeling is the formation of the gradient zone and the γ cone structure. In addition, a phenomenological model for liquid phase migration (LPM) was created and implemented using the homogenization approach. The LPM pro- cess was studied experimentally and modeled with the YAPFI software. A study of these performers was necessary to link processing and microstructure. On the performance side, the chemical interaction between cutting tools and Ti alloys was studied in detail through experimentation and modeling of diffusion. In addition, hardness and toughness models were applied to predict the longevity of studied cemented carbides. Finally, by applying ICME and material design, a high entropy alloy (HEA) alternative to Co binder was designed, produced, and tested. The research presented in this dissertation attempts to fill the gaps in the material design workflow of cemented carbides by developing new tools and methods based on ICME and CALPHAD paradigms. This goal is achieved by studying different length scales, processing methods, microstructure, properties, and performance of cemented carbides.
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| 2. |
- Johansson, Christian, 1980-
(författare)
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Knowledge engineering in the virtual enterprise : exploring a maturity-based decision support
- 2007
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In product development, lead-time reduction, cost reduction, and quality improvement are issues that companies want to improve on to increase competitiveness. One recent approach to reach this - particularly in the aerospace industry where the complexity of product offers is steadily increasing - is to manage risk by forming virtual enterprises. A virtual enterprise is a network of partner companies that join on equal terms when an opportunity arises to develop a product offer, e.g. a jet engine offer, in a more agile manner than if any of the partners would realise it by themselves. They therefore team up to share risk, investment and resources - to in return also share revenue and profit. A driver for the formation of the virtual enterprise is the ability to effectively utilise partner knowledge assets. However, when sharing and managing knowledge effectively across the virtual enterprise, current practices have yet to evolve to meet the needs of knowledge workers, who may come from different aerospace companies, have different roles, belong to different disciplines and that may also be situated in geographically dispersed locations.Improving product development includes allowing developers from all disciplines to know - as early as possible in the product development process - more about the customer needs, the desired product properties, and the downstream impact of the decisions they choose to make throughout the process. Knowing about the impact in downstream phases would allow for significant time and cost savings due to the avoidance of unnecessary and expensive rework that would otherwise occur much further on in the product's life cycle.Among other things, a virtual enterprise can start organising and mapping the knowledge assets available in their teams, and information overload can be managed by assuring that the right knowledge ends up with the right person, to mention but a few things that can facilitate the everyday work of engineers and their colleagues. When working in a product development project, the virtual enterprise needs to assess the quality of the created knowledge as early as possible to devise the correct actions early. In this thesis, a Gated Maturity Assessment technique including the concept of knowledge maturity has been developed as an example of an improved stage-gate decision-making process. With this approach development teams are able to assess the knowledge maturity level in the content and rationale that is put forward as a basis for a decision - as opposed to only assessing the raw data of the results (i.e. thrust, weight, fuel burn, etc.). Knowledge maturity is used to support decision makers when in the process of assessing a decision base to make a decision whether to go ahead, abort the process, or order rework to be done. Naturally, if the decision base is poor, a decision to go ahead should probably not be taken, as the consequences might be negative. In assessing maturity, decision makers can determine at decision points if the knowledge base is good enough to move forward to the next step in the jet engine component design, if there is need for rework, and what specific areas need to be improved. Decision makers can divert and focus resources to areas of importance due to, for instance, too low maturity levels.Knowledge maturity is a way to - using a criteria scale that prescribes the knowledge needed at each level - help development teams assess and visualise how well they know what they know, and subsequently, what they need to know. This thesis explores the feasibility of using knowledge maturity as a way of supporting knowledge engineering in the context of a development process in aeronautics.
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| 3. |
- Johansson, Christian, 1980-
(författare)
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Knowledge maturity as decision support in stage-gate product development : a case from the aerospace industry
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In today’s fast-paced industry where fight for market share is fierce and reaching the market ahead of competition imperative, product development is a target for lead-time reductions. In this context, in product development in stage-gate processes, decisions need to be made even though knowledge and information are scarce and flawed. The challenge is how to support the decisions that are made in light of uncertainty and ambiguity. The thesis moves from analysing the role of the stage-gate process within the aerospace industry. The stage-gate process was more than a decision making mechanism, and instead a mechanism that facilitated communication, discussion and knowledge sharing between team members, as well as supported knowledge creation and shaping of the boundaries between people’s different perceptions of the knowledge base. However, the communicative and negotiative function of the stage-gate was highly dependent on the ability of the participating individuals to reflect on the status and quality of the available knowledge assets used throughout the process. To make this reflective activity an explicit part of the stage-gate practice, this thesis proposes the application of a knowledge maturity concept at the gates to raise the decision makers’ awareness of the status of the knowledge assets handled at the decision point. The knowledge maturity concept considers three basic dimensions: input, method/tool and experience/expertise in assessing the knowledge base maturity. The scale is intended to act as a boundary object, facilitating the knowledge creation process by highlighting the current status of the knowledge base and making stakeholders aware of the nature of the project’s uncertainties and ambiguities. In the knowledge maturity concept, its purpose is to support design teams at the gates in taking appropriate action, mitigating risk and focusing their efforts on improving the knowledge assets where it is needed most, regarding the situation at hand and, finally, to make more confident decisions.The thesis was developed within the EU FP6 VIVACE (Value Improvement through a Virtual Aeronautical Collaborative Enterprise) and EU FP7 CRESCENDO (Collaborative and Robust Engineering using Simulation Capability Enabling Next Design Optimisation) projects, and within the Faste Laboratory, a VINNOVA Excellence Centre involving partners from the Swedish manufacturing industry.
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| 4. |
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| 5. |
- Bojesson, Catarina
(författare)
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Enabling Dynamic Capability : Managing and Organizing for Change
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This doctoral thesis is based on a longitudinal single-case study conducted over five years within a product development context at a manufacturing company. In dynamic environments that demand flexibility and adaptability, it is essential to understand how organizations can improve dynamic capabilities to remain viable and competitive during periods of turbulence and change. This challenge is especially central to product development organizations offering customer-specific products as it tends to increase organizational complexity. An excessive focus on internal coordination and control to manage this complexity has led to inertia due to establishment of strict, rigid processes and hierarchical bureaucracies within organizational management and design.This study aims to contribute with new knowledge on how organizations operating in dynamic contexts can develop adaptability to changing needs. Specifically, it seeks to understand how to design and manage organizations to increase their preparedness for and adaptability to change. Investigating the factors and mechanisms that influence an organization's dynamic capability can provide insights into the sources of inertia and support the transition toward a more dynamic structure. The longitudinal study is based on data collected through an initial interview study followed by a questionnaire study, and finally through a concluding interview study. The research has been phenomenon-driven; as the organization’s circumstances have evolved, the focus of the study has shifted accordingly. Emerging from the aggregated results of the longitudinal study, the overall scope of the research is the change process, transitioning from a rigid to a more dynamic organization. Research findings are presented in five appended papers.Analysis from literature studies and the empirical study show that the primary focus on improving performance often centers on internal efficiency. However, within the case company, tension arose between the desire of strict control according to predefined processes and plans and the actual need for flexibility. Dynamic contexts require working processes that facilitate reactive problem-solving, creativity, and flexibility, as well as managers capable of going back and forth between management styles to benefit performance. Successful organizational reconfiguration depends on developing the conditions that enable the firm's dynamic capability in relation to its context. This involves identifying both the microfoundations that generate dynamic capability and the internal and external constraints to change.Considering the external environment is crucial for developing an understanding of how to best organize and manage resources and capabilities, which places demands on managerial capabilities. Managers must possess the skills to monitor the external environment and formulate strategies to respond to changing conditions, as their interpretation of the external environment will influence their decisions, which will subsequently enable or hinder possible actions. The design of organizations will impact the ability to rearrange resources and capabilities. Processes and working procedures must allow for reconfigurations to respond swiftly to changing constraints or opportunities. The use of multiple theoretical perspectives has been imperative in the analysis of the data, and the theoretical contribution extends to exploration of various factors and mechanisms that influence an organization's dynamic capability.
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| 6. |
- Dahlén, Ewa
(författare)
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Rektorn och den dubbla styrningen : en studie om gymnasierektors uppdrag i styrkedjan
- 2023
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In a global education policy context, school leadership has grown in importance in relation to improving school outcomes as well as equity in education. At the same time, during the last decades, the Swedish school system has undergone several large-scale national education reforms. Reforms that have changed the relations between the different levels in the decentralised Swedish school system and at the same time created debates about the purpose and goals of the school system. These debates are based in different perspectives and shaped by various school discourses. The result discourse connected to the perspective of marketization and the democratic discourse connected to the perspective of social inclusion and equality. These are two central discourses who proclaim different views on how challenges within the school system should best be solved. The purpose of this study is to contribute to knowledge about the mission and responsibilities of principals in upper secondary schools in the Swedish school system. The study takes its point of departure in observations of follow-up meetings between principals within upper secondary schools and the local education authority (LEA). This study has three theoretical contributions. The first contribution concerns knowledge of the principal’s mission, assignment, and work tasks. The second contribution is knowledge of how the result discourse and the democratic discourse are used in conversations about the principal’s mission, assignment, and work tasks. The third contribution is knowledge of the interaction between the principal and the LEA, different levels in the decentralised Swedish school system, in the context of follow-up meetings. The results show that LEAs describe the principal’s mission in three parts – economy, administration, and pedagogy. The two discourses are used in all three of the missions where they sometimes collide, creating a discursive conflict and sometimes co-exist without conflict. The results also show that the LEA and principals often have a common view of the purpose and goal of the school system, but there is seldom a common strategy for how these goals are to be achieved. This study contributes to an understanding how LEAs and political governance shape the role of the principals, but more studies are needed.
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| 7. |
- Frick, Andreas, Docent, et al.
(författare)
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Neuroimaging, genetic, clinical, and demographic predictors of treatment response in patients with social anxiety disorder
- 2020
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Ingår i: Journal of Affective Disorders. - : Elsevier BV. - 0165-0327 .- 1573-2517. ; 261, s. 230-237
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Tidskriftsartikel (refereegranskat)abstract
- Background: Correct prediction of treatment response is a central goal of precision psychiatry. Here, we tested the predictive accuracy of a variety of pre-treatment patient characteristics, including clinical, demographic, molecular genetic, and neuroimaging markers, for treatment response in patients with social anxiety disorder (SAD). Methods: Forty-seven SAD patients (mean±SD age 33.9 ± 9.4 years, 24 women) were randomized and commenced 9 weeks’ Internet-delivered cognitive behavior therapy (CBT) combined either with the selective serotonin reuptake inhibitor (SSRI) escitalopram (20 mg daily [10 mg first week], SSRI+CBT, n = 24) or placebo (placebo+CBT, n = 23). Treatment responders were defined from the Clinical Global Impression-Improvement scale (CGI-I ≤ 2). Before treatment, patients underwent functional magnetic resonance imaging and the Multi-Source Interference Task taxing cognitive interference. Support vector machines (SVMs) were trained to separate responders from nonresponders based on pre-treatment neural reactivity in the dorsal anterior cingulate cortex (dACC), amygdala, and occipital cortex, as well as molecular genetic, demographic, and clinical data. SVM models were tested using leave-one-subject-out cross-validation. Results: The best model separated treatment responders (n = 24) from nonresponders based on pre-treatment dACC reactivity (83% accuracy, P = 0.001). Responders had greater pre-treatment dACC reactivity than nonresponders especially in the SSRI+CBT group. No other variable was associated with clinical response or added predictive accuracy to the dACC SVM model. Limitations: Small sample size, especially for genetic analyses. No replication or validation samples were available. Conclusions: The findings demonstrate that treatment outcome predictions based on neural cingulate activity, at the individual level, outperform genetic, demographic, and clinical variables for medication-assisted Internet-delivered CBT, supporting the use of neuroimaging in precision psychiatry.
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| 8. |
- Herman, Stephanie, et al.
(författare)
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Integration of magnetic resonance imaging and protein and metabolite CSF measurements to enable early diagnosis of secondary progressive multiple sclerosis
- 2018
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Ingår i: Theranostics. - : Ivyspring International Publisher. - 1838-7640. ; 8:16, s. 4477-4490
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Tidskriftsartikel (refereegranskat)abstract
- Molecular networks in neurological diseases are complex. Despite this fact, contemporary biomarkers are in most cases interpreted in isolation, leading to a significant loss of information and power. We present an analytical approach to scrutinize and combine information from biomarkers originating from multiple sources with the aim of discovering a condensed set of biomarkers that in combination could distinguish the progressive degenerative phenotype of multiple sclerosis (SPMS) from the relapsing-remitting phenotype (RRMS). Methods: Clinical and magnetic resonance imaging (MRI) data were integrated with data from protein and metabolite measurements of cerebrospinal fluid, and a method was developed to sift through all the variables to establish a small set of highly informative measurements. This prospective study included 16 SPMS patients, 30 RRMS patients and 10 controls. Protein concentrations were quantitated with multiplexed fluorescent bead-based immunoassays and ELISA. The metabolome was recorded using liquid chromatography-mass spectrometry. Clinical follow-up data of the SPMS patients were used to assess disease progression and development of disability. Results: Eleven variables were in combination able to distinguish SPMS from RRMS patients with high confidence superior to any single measurement. The identified variables consisted of three MRI variables: the size of the spinal cord and the third ventricle and the total number of T1 hypointense lesions; six proteins: galectin-9, monocyte chemoattractant protein-1 (MCP-1), transforming growth factor alpha (TGF-alpha), tumor necrosis factor alpha (TNF-alpha), soluble CD40L (sCD40L) and platelet-derived growth factor AA (PDGF-AA); and two metabolites: 20 beta-dihydrocortisol (20 beta-DHF) and indolepyruvate. The proteins myelin basic protein (MBP) and macrophage-derived chemokine (MDC), as well as the metabolites 20 beta-DHF and 5,6-dihydroxyprostaglandin F1a (5,6-DH-PGF1), were identified as potential biomarkers of disability progression. Conclusion: Our study demonstrates, in a limited but well-defined and data-rich cohort, the importance and value of combining multiple biomarkers to aid diagnostics and track disease progression.
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| 9. |
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| 10. |
- Jangmo, Andreas, et al.
(författare)
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Attention-Deficit/Hyperactivity Disorder, School Performance, and Effect of Medication
- 2019
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Ingår i: Journal of the American Academy of Child and Adolescent Psychiatry. - : Elsevier. - 0890-8567 .- 1527-5418. ; 58:4, s. 423-432
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Individuals with attention-deficit/hyperactivity disorder (ADHD) are at increased risk for poor school performance, and pharmacological treatment of ADHD may have beneficial effects on school performance. Conclusions from previous research have been limited by small sample sizes, outcome measures, and treatment follow-up. The current study analyzed school performance in students with ADHD compared to students without ADHD, and the association between pharmacological treatment of ADHD and school performance.METHOD: A linkage of Swedish national registers covering 657,720 students graduating from year 9 of compulsory school provided measures of school performance, electronically recorded dispensations of ADHD medication, and potentially confounding background factors such as parental socioeconomic status. Primary measures of school performance included student eligibility to upper secondary school and grade point sum.RESULTS: ADHD was associated with substantially lower school performance independent of socioeconomic background factors. Treatment with ADHD medication for 3 months was positively associated with all primary outcomes, including a decreased risk of no eligibility to upper secondary school, odds ratio = 0.80, 95% confidence interval (CI) = 0.76-0.84, and a higher grade point sum (range, 0.0-320.0) of 9.35 points, 95% CI = 7.88-10.82; standardized coefficient = 0.20.CONCLUSION: ADHD has a substantial negative impact on school performance, whereas pharmacological treatment for ADHD is associated with higher levels in several measures of school performance. Our findings emphasize the importance of detection and treatment of ADHD at an early stage to reduce the negative impact on school performance.
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