Positive displacement compounding of a heavy duty diesel engine

A helical screw type positive displacement (PD) compressor and expander was considered as an alternative to the turbocharger and the power turbine in the Cummins advanced turbocompound engine. The Institute of Gas Technology (IGT) completed the design, layout, and performance prediction of the PD machines. The results indicate that a screw compressor-expander system is feasible up to at least 750 HP, dry operation of the rotors is feasible, cost and producibility are uncertain, and the system will yield about 4% improvement in brake specific fuel consumption (BSFC) over the advanced turbocompound engine

Phase control and measurement in digital microscopy

The ongoing merger of the digital and optical components of the modern microscope is creating opportunities for new measurement techniques, along with new challenges for optical modelling. This thesis investigates several such opportunities and challenges which are particularly relevant to biomedical imaging. Fourier optics is used throughout the thesis as the underlying conceptual model, with a particular emphasis on three--dimensional Fourier optics. A new challenge for optical modelling provided by digital microscopy is the relaxation of traditional symmetry constraints on optical design. An extension of optical transfer function theory to deal with arbitrary lens pupil functions is presented in this thesis. This is used to chart the 3D vectorial structure of the spatial frequency spectrum of the intensity in the focal region of a high aperture lens when illuminated by linearly polarised beam. Wavefront coding has been used successfully in paraxial imaging systems to extend the depth of field. This is achieved by controlling the pupil phase with a cubic phase mask, and thereby balancing optical behaviour with digital processing. In this thesis I present a high aperture vectorial model for focusing with a cubic phase mask, and compare it with results calculated using the paraxial approximation. The effect of a refractive index change is also explored. High aperture measurements of the point spread function are reported, along with experimental confirmation of high aperture extended depth of field imaging of a biological specimen. Differential interference contrast is a popular method for imaging phase changes in otherwise transparent biological specimens. In this thesis I report on a new isotropic algorithm for retrieving the phase from differential interference contrast images of the phase gradient, using phase shifting, two directions of shear, and non--iterative Fourier phase integration incorporating a modified spiral phase transform. This method does not assume that the specimen has a constant amplitude. A simulation is presented which demonstrates good agreement between the retrieved phase and the phase of the simulated object, with excellent immunity to imaging noise

Phase control and measurement in digital microscopy

The ongoing merger of the digital and optical components of the modern microscope is creating opportunities for new measurement techniques, along with new challenges for optical modelling. This thesis investigates several such opportunities and challenges which are particularly relevant to biomedical imaging. Fourier optics is used throughout the thesis as the underlying conceptual model, with a particular emphasis on three--dimensional Fourier optics. A new challenge for optical modelling provided by digital microscopy is the relaxation of traditional symmetry constraints on optical design. An extension of optical transfer function theory to deal with arbitrary lens pupil functions is presented in this thesis. This is used to chart the 3D vectorial structure of the spatial frequency spectrum of the intensity in the focal region of a high aperture lens when illuminated by linearly polarised beam. Wavefront coding has been used successfully in paraxial imaging systems to extend the depth of field. This is achieved by controlling the pupil phase with a cubic phase mask, and thereby balancing optical behaviour with digital processing. In this thesis I present a high aperture vectorial model for focusing with a cubic phase mask, and compare it with results calculated using the paraxial approximation. The effect of a refractive index change is also explored. High aperture measurements of the point spread function are reported, along with experimental confirmation of high aperture extended depth of field imaging of a biological specimen. Differential interference contrast is a popular method for imaging phase changes in otherwise transparent biological specimens. In this thesis I report on a new isotropic algorithm for retrieving the phase from differential interference contrast images of the phase gradient, using phase shifting, two directions of shear, and non--iterative Fourier phase integration incorporating a modified spiral phase transform. This method does not assume that the specimen has a constant amplitude. A simulation is presented which demonstrates good agreement between the retrieved phase and the phase of the simulated object, with excellent immunity to imaging noise

Minimising leg length inequality after total hip replacement.

The total hip replacement is one of the most effective medical interventions undertaken, with high reported rates of pain relief and patient satisfaction 1,2. Leg length inequality (LLI) following total hip replacement was first recognised by Charnley when the operation was popularised but has only recently increased in prominence in the literature. The definition of an unacceptable value of LLI is controversial and is complicated not only by the lack of agreement of significance but also by the fact that for any given magnitude of LLI, only a proportion will be symptomatic. This thesis begins by exploring the opinions of British Hip Society (BHS) members to generate an expert opinion on acceptable values. Findings were in broad agreement with the literature, with 6784% of respondents stating they believed that LLI of less than 10mm would always be within the bounds of acceptable practice. A second survey of BHS members regarding methods of minimising LLI intra-operatively identified that 77% of surgeons use the Shuck technique during every total hip replacement, and that 11% use a commercial device. Chapter four evaluated five commonly used intra-operative tests and concluded that when used in combination these tests could produce acceptable values of LLI. Most reliance was placed on the Shuck technique during decision making. Results from this work identified scope for development of a novel device to be used as an adjunct to the Shuck test as an indirect measurement of leg length. A device was designed and manufactured and preliminary results from in vivo studies show a narrow range of both distraction distance and force applied during the Shuck test. These results indicate that the device could be developed further to standardise the Shuck test and use it as an adjunct to train junior surgeons how to assess leg length, minimising the requirement for subjective and invasive methods

Experimental and Numerical Studies of the Seismic Performance of Precast Segmental Concrete Columns

Precast segmental concrete column has many advantages, but its applications are limited due to insufficient knowledge about its seismic performance. This thesis aims to investigate the seismic performance of precast segmental column. Cyclic tests and shake table tests were carried out to evaluate the static and dynamic performance of the precast segmental column. Extensive numerical studies were also conducted as supplementary to the experimental results for better understanding of its seismic performance

PRODUCTION, EXCHANGE AND SOCIAL INTERACTION IN THE GREEN RIVER REGION OF WESTERN KENTUCKY: A MULTISCALAR APPROACH TO THE ANALYSIS OF TWO SHELL MIDDEN SITES

The Green River region of western Kentucky has been a focus of Archaic period research since 1915. Currently, the region is playing an important role in discussions of Archaic hunter-gatherer cultural complexity. Unfortunately, many of the larger Green River sites contain several archaeological components ranging from the Early to Late Archaic periods. Understanding culture change requires that these multiple components somehow be sorted and addressed individually. Detailed re-analyses of Works Progress Administration (WPA) era artifact collections from two archaeological sites in the Green River region – the Baker (15Mu12) and Chiggerville (15Oh1) shell middens – indicate that these sites are relatively isolated Middle and Late Archaic components, respectively. The relatively unmixed character of Baker and Chiggerville makes these sites excellent candidates for evaluating aspects of complexity during the Archaic. After developing a theoretical basis for evaluating the relative complexity of the social organization of the Baker and Chiggerville site inhabitants on the basis of the material record they left behind, I employ detailed analyses of the bone, antler, and stone tools from these two sites to examine six microscalar aspects of complexity – technological organization, subsistence, specialization, leadership, communication networks, and exchange. These microscalar aspects of complexity all can be linked materially to the archaeological record of the Green River region and can be evaluated as proxies for changes in social organization among the hunter-gatherers who inhabited this region during the Middle and Late Archaic periods. Although the Baker assemblage indicated greater complexity in communication networks and certain proxies for leadership and technological organization, most indicators suggest that the Chiggerville site inhabitants were the more complexly organized group and were in the process of developing a tribal-like social formation. This research, therefore, tentatively supports the hypothesis of increasing complexity through time during the Archaic. However, marked differences in the technological strategies utilized by the Baker and Chiggerville site inhabitants indicates these groups may not have been historically related, thereby violating one of the primary assumptions of the project. If this alternative hypothesis is confirmed through additional research, then no conclusions concerning change through time can be derived from this study

Interactional Competence in L2 English Upper Secondary Oral Assessment: Exploring Teachers’ Understandings and Practices

I denne masteroppgaven har jeg undersøkt hvordan interaksjonell kompetanse (interactional competence, IC) er inkludert i læreres vurdering av muntlige ferdigheter i engelskfaget på videregående skole. Læreplanen (LK20) legger vekt på at muntlige ferdigheter i engelsk handler om å skape mening gjennom å lytte, tale og samtale. Det er derfor relevant å undersøke hvordan interaksjonell kompetanse blir inkludert og operasjonalisert i muntlig vurdering ettersom samhandling er en sentral del av elevenes muntlige ferdigheter. Læreres oppfatninger og praksis har blitt undersøkt gjennom en mixed methods tilnærming ved bruk av spørreundersøkelse, intervjuer og analyse av læreres oppgaver og vurderingskriterier for muntlig vurdering. Et teoretisk rammeverk for interaksjonell kompetanse tilpasset muntlig vurdering i engelsk på videregående skole blir presentert i studien og funnene har blitt analysert ut fra dette og annen relevant teori. Funnene fra studien viser at begrepet IC er ukjent for de fleste, men at lærere likevel oppfatter at denne kompetansen omhandler ferdigheter knyttet til samhandling med andre. Når lærerne blir bedt om å foreslå hvordan IC kan bli operasjonalisert i kriterier for muntlig vurdering, foreslår de fleste kriterier som reflekterer kjennetegnene på IC som er definert i oppgavens rammeverk. Det indikerer at det teoretiske rammeverket som er definert og foreslått i denne oppgaven, kan være passende å inkludere i muntlig vurdering i engelskfaget på videregående skole. Videre viser analysen at vurderingskriterier relatert til elevers kommunikative ferdigheter er i mindre grad språkliggjort og operasjonalisert enn kriterier som omhandler språk. Likevel rapporterer majoriteten av lærere å bruke gruppevurderinger som muntlig vurdering, en oppgaveform som inkluderer samhandling. Dette indikerer at det er behov for et rammeverk som kan konkretisere og operasjonalisere også deler av elevers muntlige ferdigheter som ikke er knyttet til språklige elementer. Studien finner også at det i varierende grad er samsvar mellom læreres oppfatninger og praksis rundt muntlig vurdering, noe som indikerer at det er potensiale for å konkretisere flere aspekter knyttet til elevers muntlige ferdigheter. Jeg håper at denne oppgaven kan bidra til å utvikle læreres begrepsapparat knyttet til samhandling og inspirere til å inkludere konkrete kriterier knyttet til de implisitte strategiene som er en viktig del av elevers muntlige og kommunikative kompetanse. IC er lite undersøkt i sammenheng med muntlig vurdering i engelskfaget på videregående skole og videre forskning er nødvendig for å kunne vurdere effekten av å inkludere IC i vurdering.Engelsk mastergradsoppgaveENG350MAHF-ENGMAHF-LÆF