Mechanical properties testing and results for thermal barrier coatings

Thermal Barrier Coatings (TBC's) provide a significant challenge in the evaluation of their mechanical properties in ways that provide data that is not specimen dependent. The paper reviews various developments of the principal author over the past several years for both plasma sprayed and physical vapor deposited (PVD) materials, as well as new data on the fatigue behavior of one material system. The test methods that have been employed address tensile and compressive modulus and ultimate strength, tensile and compressive fatigue strength, and interfacial strength. This testing is now underway. Property testing is especially difficult for TBC's owing to the limitation on fabrication thickness of the coating. Bending tests are not used as these tests do not provide sufficiently uniform states of strain for property evaluations. Test specimens with uniform states of axial stress have been devised for each material system. The results show that the material property results between various experimenters and experimental methods are not yet consistent. However, the results provide critical design data at a suitable level of accuracy for life prediction. The paper will review both tensile and compressive mechanical testing of uniaxial specimens showing property dependencies on material density and temperatures for both material systems. Successful test results for both tensile and compressive fatigue loadings will be given. The test data shows that the fatigue strength of the TBC's is highly stress dependent in both loading conditions and is likely to depend on stress range and not mean stress. The fatigue strength of the plasma sprayed TBC's appears to increase with elevated temperatures in a range of temperatures below the creep activation temperature for the materials. The plasma sprayed TBC materials have been confirmed to have cyclic hysteresis at all temperature levels down to room temperature. Limited failure analysis data for various specimens suggest that the failure modes are driven by normal geometric discontinuities in the TBC's

Spin-dynamic field coupling in strongly THz driven semiconductors : local inversion symmetry breaking

We study theoretically the optics in undoped direct gap semiconductors which are strongly driven in the THz regime. We calculate the optical sideband generation due to nonlinear mixing of the THz field and the near infrared probe. Starting with an inversion symmetric microscopic Hamiltonian we include the THz field nonperturbatively using non-equilibrium Green function techniques. We find that a self induced relativistic spin-THz field coupling locally breaks the inversion symmetry, resulting in the formation of odd sidebands which otherwise are absent.Comment: 8 pages, 6 figure

Quasienergy Spectroscopy of Excitons

We theoretically study nonlinear optics of excitons under intense THz irradiation. In particular, the linear near infrared absorption and resonantly enhanced nonlinear sideband generation are described. We predict a rich structure in the spectra which can be interpreted in terms of the quasienergy spectrum of the exciton, via a remarkably transparent expression for the susceptibility, and show that the effects of strongly avoided quasienergy crossings manifest themselves directly, both in the absorption and transmitted sidebands.Comment: 4 pages RevTex, 3 eps figs included, as publishe

Multiplication and Composition in Weighted Modulation Spaces

We study the existence of the product of two weighted modulation spaces. For this purpose we discuss two different strategies. The more simple one allows transparent proofs in various situations. However, our second method allows a closer look onto associated norm inequalities under restrictions in the Fourier image. This will give us the opportunity to treat the boundedness of composition operators.Comment: 49 page

Strong-field terahertz-optical mixing in excitons

Driving a double-quantum-well excitonic intersubband resonance with a terahertz (THz) electric field of frequency \omega_{THz} generated terahertz optical sidebands \omega=\omega_{THz}+\omega_{NIR} on a weak NIR probe. At high THz intensities, the intersubband dipole energy which coupled two excitons was comparable to the THz photon energy. In this strong-field regime the sideband intensity displayed a non-monotonic dependence on the THz field strength. The oscillating refractive index which gives rise to the sidebands may be understood by the formation of Floquet states, which oscillate with the same periodicity as the driving THz field.Comment: 4 pages, 6 figure

Langtidsovervåking av miljøkvaliteten i kystområdene av Norge. Årsrapport 1996

Kystovervåkingsprogrammet skal gi en oversikt over miljøtilstanden m.h.t. næringssalter og effektene av disse på alge- og dyresamfunn fra svenskegrensen til Fedje. Utvikling over tid overvåkes innen fagdisiplinene hydrografi, hydrokjemi, planteplankton, bløtbunnsfauna og hardbunnsflora og -fauna. Året 1996 ble innledet med en kald vinter og vår. Vanntemperaturen i Skagerrak ned til ca. 25 m var i januar - februar kaldere enn gjennomsnittet for 1980-1990, mens samme periode i 1995 var uvanlig varm. Til forskjell fra 1995 var det ingen flom på kontinentet eller på Østlandet i 1996, og det resulterte i små tilførsler av næringssalter fra land. Sammenlignet med langtidsobservasjoner fra Arendalstasjonene (1980-90) var 1996 et år med lavere næringssaltkonsentrasjoner i de øvre vannmasser vinter og vår og for de løste næringssaltene også tildels sommeren og høsten. C/N-forholdet i stortare fra Sørlandskysten var meget høyt og kan indikere næringsbegrenset algevekst på Sørlandskysten sommeren 1996. Utbredelse og forekomst av fastsittende alger var generelt sett noe redusert i 1996 i forhold til 1995 og mer lik hva som ble funnet i 1993/94. Variasjonene kan sees i sammenheng med vinter/vår temperaturene. Fortsatt tilvekst av tareskog i Skagerrak gjør stasjonene mer homogene. Forekomst av organismer på bløt- og hardbunn viste en normal øst-vest gradient, med økende artsantall og diversitet mot vest. Bløtbunnsfaunaen viste ingen større endringer fra 1995 til 1996. For enkelte stasjoner ble det funnet en nedgang i individtall, mens det ble funnet en økning for andre stasjoner, uten at det er noen klar årsakssammenheng eller tendens i variasjonene

Linear optical absorption spectra of mesoscopic structures in intense THz fields: free particle properties

We theoretically study the effect of THz radiation on the linear optical absorption spectra of semiconductor structures. A general theoretical framework, based on non-equilibrium Green functions, is formulated, and applied to the calculation of linear optical absorption spectrum for several non-equilibrium mesoscopic structures. We show that a blue-shift occurs and sidebands appear in bulk-like structures, i.e., the dynamical Franz-Keldysh effect [A.-P. Jauho and K. Johnsen, Phys. Rev. Lett. 76, 4576 (1996)]. An analytic calculation leads to the prediction that in the case of superlattices distinct stable steps appear in the absorption spectrum when conditions for dynamical localization are met.Comment: 13 Pages, RevTex using epsf to include 8 ps figures. Submitted to Phys. Rev. B (3 April 97

Addressing reoffending through addressing offender mental health: Exploring the viability of the Change Laboratory method as means of promoting social innovation in the delivery of integrated mental health care offenders in prison services.

Recidivism rates are a typical measure of the success of the criminal justice system. Effective collaboration is required between criminal justice services and mental health services to effectively achieve offender rehabilitation and reduce reoffending. Previous work on collaborative practice in the Norwegian prison systems (Hean et al., 2016) has concluded that more effective models of collaboration are required between the mental health and criminal justice services. It made the case for implementation of the Change Laboratory Method (CL) of interagency working and workforce transformation as a means of supporting interagency collaborative practice in this context. The CL has been used successfully and extensively by researchers internationally to transform interagency working practices in a wide range of countries (e.g., Finland, Brazil; New Zealand) and contexts (e.g. child protection, secondary health care and business) with an extensive list of products and work transformations arising from them (e.g. new adaptations of care pathways, new forms of service delivery) (Kerosuo & Engeström, 2003, Warmington et al., 2005, Tolviainen, 2007, Virkkunen et al., 2014). However, CLs as interventions are a new idea in Norwegian prison development, none as yet having been applied across organisational borders or specifically to the challenges facing collaboration between correctional and health and welfare services. It is essential therefore to explore first the feasibility of the such a possible intervention before implementation. The aim of this developmental project was therefore to conduct first the ethnographic phase of a CL intervention in a case study Norwegian prison, and identify issues that would benefit from future intervention, organizational development and learning. Second, the project explored the viability of the CL as a means of addressing these and improving collaboration between Correctional and Mental Health Services. The purpose of the first CL phase is for the interventionist team to describe the current situation of collaboration in the prison. The focus was to reveal challenges (theoretically described as contradictions) by seeing them as systemic causes of problems in collective activity instead of indications of individuals’ actions. Data from the first CL phase was gathered through interviews, observations and documentary data from an open department at the prison in Region West of the Norwegian Correctional Services. A cultural-historical activity theory approach guided the methods of data collection and analysis. This meant that the collaborative tools and voices of frontline workers, such as officers and mental health workers were brought to the fore. The analysis illustrated the complexity of the collaboration network in the prison, its variety of actors, and its challenges. This report presents the characteristics of current collaboration practices, examples of good practice as well as its challenges, and the complexity of the collaboration network between the mental health and prison services. These collaboration practices have developed with an aim to enhance the welfare of offenders and to reduce recidivism. However, the increasing needs of offender, of which loneliness and mental health were central, have come into play, which challenges the outputs of the services and collaboration between service providers. We report here three potential contradictions for future exploration by the prison that arose from the analysis. The first pertained to the challenges facing the BRIK assessment tool. BRIK is a tool used in the prison through which information on offender’s needs and resources are collected and evaluated by the officer and offender together. However, a lack of time to keep the content of BRIK regularly updated and ensuring the quality of its content ,is a challenge. In the report, we suggest that these challenges are connected to the fact that users of the tool (members of interagency meetings, offenders and officers) perceive the meaning and purpose of BRIK differently. For offenders, BRIK represents a tool to get more face-to-face time with the officer, which points to the inmate’s need of having more social contact. However, for the officer BRIK is one of their work tasks, a task required of them by Correctional Services authorities. For members of interagency meetings with health and other services, however, BRIK is a tool for understanding an offender’s motivation behind any specific request they might make of the meeting. This contradiction between different needs and meanings of purpose of BRIK challenges the effective use of the instrument. The second contradiction lay in observations that the prison officer`s purpose of work has changed over time but the development of tools to support their work has not kept up with these changing objectives. The third contradiction pertained to the suboptimal work organization, development, and flow of psychological knowledge in the prison. The purpose of this ethnographic phase of the CL presented in this report is not to fully elaborate these above contradictions collected by researchers as it essential to the model that these are articulated and understood by the prison, mental health and other prison based actors themselves when participating in future interventions. The contradictions raised by the ethnographic phase must be further revealed within this group of actors working together. Based on the potential contradictions raised in the ethnographic phase of the CL we now recommend a second phase of the CL in which our observations and findings of the collaborative network would be presented as mirror data to representatives of this network. This next phase would seek to open up new perspectives and motivate people in the prison to examine and develop their current practices further and collectively. During the process of CL, the organization would learn to solve their own contradictions and develop their activity. However, to ensure the implementation of this second phase ,careful negotiation, sensitivity and commitment of the researchers, prison management and frontline professionals involved, is required