Automatic Detection of Egg Shell Cracks

The challenge was to find a reliable, non-intrusive means of detecting cracks in eggs. Intensity data from eggs were collected by VisionSmart for the group to analyse. Given the short time period three main questions were addressed. 1) Is there a feature of the intensity data which detects, and discriminates between pinholes, cage marks and cracks? 2) Are there ways to improve the current data collection process? 3) Are there other data collection methods which should be tried? A partial positive response to 1) is presented and describes the many problems that arose. Some answers to 2) and 3) are also presented

YSO jets in the Galactic plane from UWISH2 – III. Jets and outflows in Cassiopeia and Auriga

We present the analysis of 35.5 deg2 of images in the 1–0 S(1) line of H2 from the UK Widefield Infrared Survey for H2 (UWISH2) towards Cassiopeia and Auriga. We have identified 98 Molecular Hydrogen emission-line Objects (MHOs) driven by Young Stellar Objects, 60 per cent of which are bipolar outflows and all are new discoveries. We estimate that the UWISH2-extended emission object catalogue contains fewer than 2 per cent false positives and is complete at the 95 per cent level for jets and outflows brighter than the UWISH2 detection limit. We identified reliable driving source candidates for three quarters of the detected outflows, 40 per cent of which are associated with groups and clusters of stars. The driving source candidates are 20 per cent protostars, the remainder are Classical T-Tauri Stars. We also identified 15 new star cluster candidates near MHOs in the survey area. We find that the typical outflow identified in the sample has the following characteristics: the position angles are randomly orientated; bipolar outflows are straight within a few degrees; the two lobes are slightly asymmetrical in length and brightness; the length and brightness of the lobes are not correlated; typical time gaps between major ejections of material are 1–3 kyr, hence FU-Ori or EX-Ori eruptions are most likely not the cause of these, but we suggest MNors as a possible source. Furthermore, we find that outflow lobe length distributions are statistically different from the widely used total length distributions. There are a larger than expected number of bright outflows indicating that the flux distribution does not follow a power law

Pressure injury in Australian public hospitals: a cost-of-illness study

Objective: Pressure injuries (PI) are largely preventable and can be viewed as an adverse outcome of a healthcare admission, yet they affect millions of people and consume billions of dollars in healthcare spending. The existing literature in Australia presents a patchy picture of the economic burden of PI on society and the health system. The aim of the present study was to provide a more comprehensive and updated picture of PI by state and severity using publicly available data. Methods: A cost-of-illness analysis was conducted using a prevalence approach and a 1-year time horizon based on data from the existing literature extrapolated using simulation methods to estimate the costs by PI severity and state subgroups. Results: The treatment cost across all states and severity in 2012–13 was estimated to be A$983 million per annum, representing approximately 1.9$820 million per annum. These estimates were associated with a total number of 121 645 PI cases in 2012–13 and a total number of 524 661 bed days lost. Conclusions: The costs estimated in the present study highlight the economic waste for the Australian health system associated with a largely avoidable injury. Wastage can also be reduced by preventing moderate injuries (Stage I and II) from developing into severe cases (Stage III and IV), because the severe cases, accounting for 12% of cases, mounted to 30% of the total cost

Circumventing the radiation pressure barrier in the formation of massive stars via disk accretion

We present radiation hydrodynamics simulations of the collapse of massive pre-stellar cores. We treat frequency dependent radiative feedback from stellar evolution and accretion luminosity at a numerical resolution down to 1.27 AU. In the 2D approximation of axially symmetric simulations, it is possible for the first time to simulate the whole accretion phase (up to the end of the accretion disk epoch) for the forming massive star and to perform a broad scan of the parameter space. Our simulation series show evidently the necessity to incorporate the dust sublimation front to preserve the high shielding property of massive accretion disks. While confirming the upper mass limit of spherically symmetric accretion, our disk accretion models show a persistent high anisotropy of the corresponding thermal radiation field. This yields to the growth of the highest-mass stars ever formed in multi-dimensional radiation hydrodynamics simulations, far beyond the upper mass limit of spherical accretion. Non-axially symmetric effects are not necessary to sustain accretion. The radiation pressure launches a stable bipolar outflow, which grows in angle with time as presumed from observations. For an initial mass of the pre-stellar host core of 60, 120, 240, and 480 Msun the masses of the final stars formed in our simulations add up to 28.2, 56.5, 92.6, and at least 137.2 Msun respectively.Comment: 55 pages, 24 figures, accepted at Ap

Towards Versatile Robots Through Open Heterogeneous Modular Robots

Robots are important tools in our everyday life. Both in industry and at the consumer level they serve the purpose of increasing our scope and extending our capabilities. Modular robots take the next step, allowing us to easily create and build various robots from a set of modules. If a problem arises, a new robot can be assembled rapidly from the existing modules, in contrast to conventional robots, which require a time consuming and expensive development process. In this thesis we define a modular robot to be a robot consisting of dynamically reconfigurable modules. The goal of this thesis is to increase the versatility and practical usability of modular robots by introducing new conceptual designs. Until now modular robots have been based on a pre-specified set of modules, and thus, their functionality is limited. We propose an open heterogeneous design concept, which allows a modular robot to be easily extended with new functionality. In addition we introduce deformability, a new means for modular robots to perform autonomous adaptation to changing environments, and enabling parallel actuation. This thesis presents two new modular robotic concepts, the Odin and Thor modular robot. The Odin robot realizes both deformability, and is based on the open heterogeneous design concept. The Thor robot focuses on the open heterogeneous design concept. The robots are brought outside the lab, to the ICRA Planetary Robotic Contingency Challenge, to test their potential, and evaluate the concepts in a real world scenario.We encourage further research in deformability, distinguishing between parallel and collective actuation, and the ability to passively adapt to changing environments. For this thesis, deformability, and the complexities involved, started to curtail the practical usability of the modular robots presented. However, we conclude, that the open heterogeneous design concept can increase the versatility of modular robots, and bring us towards more versatile robots in general

Towards Versatile Robots Through Open Heterogeneous Modular Robots

Robots are important tools in our everyday life. Both in industry and at the consumer level they serve the purpose of increasing our scope and extending our capabilities. Modular robots take the next step, allowing us to easily create and build various robots from a set of modules. If a problem arises, a new robot can be assembled rapidly from the existing modules, in contrast to conventional robots, which require a time consuming and expensive development process. In this thesis we define a modular robot to be a robot consisting of dynamically reconfigurable modules. The goal of this thesis is to increase the versatility and practical usability of modular robots by introducing new conceptual designs. Until now modular robots have been based on a pre-specified set of modules, and thus, their functionality is limited. We propose an open heterogeneous design concept, which allows a modular robot to be easily extended with new functionality. In addition we introduce deformability, a new means for modular robots to perform autonomous adaptation to changing environments, and enabling parallel actuation. This thesis presents two new modular robotic concepts, the Odin and Thor modular robot. The Odin robot realizes both deformability, and is based on the open heterogeneous design concept. The Thor robot focuses on the open heterogeneous design concept. The robots are brought outside the lab, to the ICRA Planetary Robotic Contingency Challenge, to test their potential, and evaluate the concepts in a real world scenario.We encourage further research in deformability, distinguishing between parallel and collective actuation, and the ability to passively adapt to changing environments. For this thesis, deformability, and the complexities involved, started to curtail the practical usability of the modular robots presented. However, we conclude, that the open heterogeneous design concept can increase the versatility of modular robots, and bring us towards more versatile robots in general

Comparison between Si MOSFETs and GaN HEMTs with special emphasis on low load problems occuring in the LLC resonant converter

Det stilles store krav til likerettere brukt til å forsyne datasentere med kraft. Et av kravene er høy virkningsgrad. En av de vanligste topologiene brukt til dette formålet består av en PFC-likeretter, for å få sinusformet strøm fra nettet, etter- fulgt av en DC-link og en LLC-konverter for DC-DC omforming. Disse strøm- forsyningene har allerede høy virkningsgrad. En mulighet for å øke virknings- graden ytterligere er allikevel å redusere motstanden til transistorene når de er skrudd på. Men vanlige silisium(Si) ’metal-oxide-semiconductor field-effect transis- torer’(MOSFET) nærmer seg raskt sin teoretiske grense for sammenhengen mellom on-state motstand og fysisk størrelse. For å redusere motstanden til en gitt silisium MOSFET enda mer, er da eneste mulig å øke størrelsen. Økt størrelse betyr større parasittiske kapasitanser, noe som kan gi problemer. En av de viktigste teknologiene for økt virkningsgrad er derfor galliumni- trid(GaN) ’high electron mobility transistor’ (HEMT). GaN har overlegne materi- alegenskaper, og kan derfor gi transistorerer med bedre egenskaper. Dette inklud- erer blant annet mindre parasittiske kapasitanser for den samme on-state mot- standen. Det forventes derfor at å erstatte Si MOSFET med GaN HEMT i LLC- omformeren kan bedre virkningsgraden, samtidig som man unngår problemene som oppstår ved alt for store utgangskapasitanser. Spesielt lavlast-reguleringsproblemer forventes å kunne bli bedre. I denne rapporten vil bare LLC-omformeren bli vurdert. PFC-leddet diskuteres ikke. Mer spesifikt er det LLC-topologien med en halvbro-struktur på inngan- gen, og fullbro diodelikeretter som blir brukt. Designmetodikk, transferfunksjoner, nullspennings-svitsjing, driftmoduser og lavlastproblemer diskuteres. Andre store tema slik som for eksempel kontroll av omformeren nevnes bare kort. Si MOSFET og GaN HEMT er de eneste transistortypene som blir vurdert. Rapporten begynner med et litteraturstudie på GaN transistor, og da spesielt GaN HEMT. Dette er etterfulgt av det litteraturstudie på LLC-serie-resonans- omformeren. Mulig implementering av GaN HEMT i LLC-omformeren blir un- dersøkt. GaN HEMT og silisium MOSFETer sammenlignes direkte ved hjelp av ’figure of merit’(FOM). Spesiell vekt legges på hensyn som er viktig for ’soft- switching’-topologier slik som LLC-konverteren. Gjennom simulering i LTspice valideres noen av de diskuterte konseptene, spesielt FHA-antagelsen i utledningen av transferfunksjonen. Transferfunksjon blir også målt i lab. Resultatene viser god overensstemmelse mellom teori og simulering og lab. En LLC-modul med GaN HEMT og en annen LLC-modul med Si MOSFETer sammenlignes også gjennom labmålinger. Her vises det at GaN HEMT kan forbedre lavlastproblemene samtidig som virkningsgraden forblir den samme, og kan til og med økes noe.Rectifiers for supplying data center with power from the grid are subject to many requirements, one of which is very high efficiency. One of the most common con- verter architectures consists of a PFC rectifier stage, used for achieving sinusoidal mains current, followed by a DC-link and a LLC resonant converter for the DC-DC conversion. This topology is already quite efficient. However, one possible solu- tion to increasing the efficiency further is lowering the on-state resistance of the transistors used. Regular silicon(Si) metal-oxide-semiconductor field-effect transis- tors(MOSFET) however are quickly approaching their theoretical limit in terms of tradeoff between die size and on-state resistance. To reduce on-state resistance further, the die size must then be increased. An increased die size comes with the disadvantage of large terminal capacitances, which can lead to problems. One of the main enabling technologies for increased efficiency is therefore gal- lium nitride(GaN) high electron mobility transistors(HEMT). This is because they have smaller terminal capacitances for the same on-state resistance, owing to su- perior material properties. It is expected that replacing the Si MOSFETs in the LLC converter with GaN HEMTs could improve efficiency, while also avoiding the some of the problems that could occur with excessively large output capacitances. Especially low load regulation problems is considered in this regard. In this report, only the LLC converter will be considered. The PFC con- verter will not be discussed. More specifically the LLC topology with a half-bridge structure at the input will be considered. On the secondary side a full-bridge diode-rectifier is used. Design methods, transfer functions, zero-voltage switching, operation modes and low load problems are discussed. Other broad topics such as control is only briefly mentioned. Si MOSFETs and GaN HEMTs are the only transistor types considered. This report starts with a literature study on GaN devices, more specifically GaN HEMT. In the second part the LLC series resonant topology is discussed. Possible implementation of new GaN-switches in the LLC converter is researched. A direct comparison between GaN HEMTs and silicon MOSFETS is done. Special emphasis is put on considerations that are important to soft-switching topologies such as the LLC converter. Simulations in LTSPICE are done to validate some of the discussed concepts, especially the derived transfer function from the fundamen- tal harmonic approximation(FHA), which shows good results. Lab measurements are also done, and it is seen that the GaN HEMT can improve upon the low load problems occurring in the LLC converter when using Si MOSFETs. The results show that this is achieved with the same degree of efficiency, and using GaN HEMTs the efficiency might even be increased

Data Integration for Species Distribution Models

I denne oppgaven blir fordelingen av ferskvannsfisk i norske innsjøer estimert ved å bruke data fra to standardiserte datasett og ett opportunistisk datasett sammen med miljøbaserte kovariater til å lage en kombinert modell. Modellen er en Bayesiansk hierarkisk modell, og modelltilpasning blir utført med integrert nøstet Laplace approksimasjon, et verktøy for å utføre rask Bayesiansk inferens. Bruken av INLA gjør åpner opp for å bruke romlige Gaussiske stokastiske felter i modellen, og parametrisering av disse feltene blir analysert. Forskjellige typer data blir utforsket, og resultatene fra den kombinerte modellen blir sammenlignet med resultater fra modeller basert på de individuelle datasettene. Den kombinerte modellen får bedre resultater enn de individuelle modellene for tre av de fire artene som undersøkes.In this thesis the distribution of freshwater fish in Norwegian lakes is estimated by using data from two standardized data sets and one opportunistic data set in addition to environmental covariates to create a combined model. The model used is a Bayesian hierarchical model and model fitting is done using Integrated nested Laplace approximation (INLA), a tool for fast Bayesian inference. The use of INLA allows for the use of Gaussian random fields in the model, and parameterization of this random field is analysed. The combined model is shown to be better than all individual models for three of the four species examined