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- Johansson, Mats P., 1965-
(författare)
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Growth and microstructure of reactive sputter deposited boron nitride : carbon (BN:C) thin films
- 1995
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Growth, microstructure and mechanical properties of boron nitride: carbon (BN:C) have been studied in films prepared by reactive r.f. diode sputter deposition as well as by reactive unbalanced d.c. magnetron (UBM) sputter deposition of low resistivity boron carbide (B4C) targets. Due to the fäet that d.c. glow discharges offers a better control of the important growth parameters such as particle flux and energy distribution in both neutral and ionized states at the substrate as compared to r.f. methods, fundamental growth and plasma studies were in some detail performed in the UBM sputtering system.Films were prepared with three characteristic phase compositions; cubic c-BN:C, hexagonal (turbostratic-like) h-BN:C and a mixtures of these on Si (001) substrates. The same phase compositions were obtained in both deposition techniques. While keeping the B/N ratio close to unity, the formation of BN:C phases were mainly correlated to the energy and flux of impinging ions towards the negatively d.c. biased substrate. A c-BN:C phase formation was typically found in mixed c-BN:C and h-BN:C films prepared at high ion-to-neutral flux ratios (UBM: Ji/Jn ~24), within a narrow range in ion energies (UBM: 85 eV < Ei < 135 eV) and at low process temperatures <250 °C. However, almost single phase c-BN:C (~80 % of sp3-bonded B-N) was obtained at deposition conditions of high ion flux (UBM: Ji/Jn ~24) and low ion energy (UBM: Ei = 110 eV) whereas films deposited at much lower ion energy or at a lower ion fluxes contained exclusively h-BN:C. Also, c-BN:C films revealed a BN:C film phase evolution sequence from an initial amorphous BN:C layer followed by a highly oriented h-BN:C layer with the c-axis parallel to the film surface, to a c-BN:C layer exhibiting a (110)preferred orientation. Furthermore, as-deposited films contained 5 - 20 at% of C that was found to decrease with increasing volume fraction of c-BN:C and also with increasing J/Jn. Chemical sputtering of volatile CN species is suggested for the reduction of C in BN:C films. Nevertheless, the C in c-BN:C films is mainly present as C-C and B-C bonds.Unnoticed the presence of C, cubic phase BN:C films are shown to be formed at deposition conditions not included in the present models of c-BN growth. For example, in terms of momentum transfer, values of 200 - 250 (eV emu)% have been reported to be required for the synthesis of c-BN whereas in this study an order of magnitude higher values were found. The results thus point at an extended deposition window for cubic phase formation, with potential for using further reduced ion energies such that intrinsic compressive stress in BN can be minimized.Finally, the mechanical properties of randomly- and highly-oriented h-BN:C as well as of c-BN:C films were studied and compared to the uncoated Si substrate. Although all coated substrates showed an increased stiffness, the maybe most interesting properties were found in the highly oriented h-BN:C films with the c-axis parallel to the film surface. These films showed a predominantly elastic behaviour exhibiting an elastic recovery as high as 82% indicating high hardness values. The improved hardness and elasticity may be explained by the apparent microstructure with buckling of the hexagonal basal planes. This structure is proposed to correspond to a three dimensional strongly covalently bonded network of BN:C, similar to what has been reported for CNx films.
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| 2. |
- Yousefi Mojir, Kayvan
(författare)
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New Forms of Collaboration in Emergency Response Systems : A framework for participatory design of information systems
- 2016
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- An emergency response systems (ERS) is usually responsible for delivering essential services to save lives and minimise environmental damage in case of small, frequent or large-scale emergencies. The ongoing global financial crisis, lack of professional resources, public sector cuts and rising public expectations are some of the challenges ERSs currently are facing. At the same time, societal trends in form of large-scale disasters such as tsunamis, storms, forest fires, terror attacks, and wars in the Middle East leading to mass migration have intensified recently and globally, increasing demand for these services in the public sector. As a result, emergency response actors are often under extreme pressure, and may need to seek assistance from and cooperate with other resources in society in order to become more effective. An emerging trend in ERSs in response to the challenges, in Sweden and internationally, is to create new forms of collaboration in emergency management (e.g., cross-sector collaboration, involving citizens in e-government, and involving volunteers). While research and practice have started to show the benefits of organising ERSs in new ways, the increasingly broad set of heterogeneous stakeholders involved in the collaborations introduce various challenges. Legal issues, unclear responsibilities of actors, difficulty in the categorisation of tasks, job insurance problems, diversity in education and background of actors, and difficulty determining actors’ specific needs for IS support are some examples. Analysis of collaborations thus becomes increasingly complex, and must incorporate many aspects. Rudimentary analyses may result in failure of related projects and IS development, and ultimately in less effective collaborations. New forms of collaboration must therefore be analysed and understood rigorously, generally and in each specific context in order to develop them for ERSs and the public sector and to support actors with effective IS tools.This thesis develops and presents a framework for analysing new forms of collaboration in ERSs. It also provides an initial suggestion on how to apply the framework with a specific focus on IS development. The study was carried out as a qualitative case study based on three kinds of collaboration in the Swedish ERS: co-operative, cross-sector use of resources, involving civil volunteers in response operations and co-location of actors. The framework has fifteen dimensions. They are: Type/Role, Attitude, Training, Background, Task and Responsibility, Availability/Accessibility, Incident Type, Communication Methods, Information Technology, Emergency Supplies, Organisational Structure, Leadership, Costs/Benefits, Environment, and Regulations and Legal Issues. Sociotechnical systems theory and participatory design principles were applied to make the framework usable in the IS field. The framework can be used generally to analyse new forms of collaboration in ERSs in order to understand its different aspects and emergent challenges, such as actors’ tasks, relevant laws, leadership and organisational factors, which may otherwise be overlooked, into the analysis process. As to IS development, the framework can contribute to organisational analysis and needs analysis in the participatory design of IS for ERSs, e.g. by helping to identify key stakeholders and involve them in the development process.The framework was initially tested at the co-location case and showed several promising benefits in terms of identifying and involving stakeholders in the development process. It was deemed helpful in determining and formulating interviews, observations, and future workshops in order to explore and study all relevant dimensions of the collaboration in the early phases of participatory design. It was also felt that the framework saved time and resources. It is argued that it may offer similar benefits in similar cases, although this will require further testing with more case studies. A standardised and developed version of the framework may also be adapted to be applicable to other public sector contexts such as e-government in which new forms of collaboration and governance are in focus. Such a framework may also help to address general challenges often associated with participatory design, add formalisation to it, and contribute to shift it from an academic to a practical approach in order to derive its benefits in complex environments. The next step will be to use the framework as a departure point for analysing the potential co-operative use of resources and cross-sector collaboration in the project ‘Efficient Communal Use of Municipal Resources for Increased Safety and Security’ (ESKORT) in the municipality of Norrköping.
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