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Studentarbeid i sykepleie (bachelorgrad) - Universitetet i Nordland, Bodø, 201

RLFC: Random Access Light Field Compression using Key Views and Bounded Integer Encoding

We present a new hierarchical compression scheme for encoding light field images (LFI) that is suitable for interactive rendering. Our method (RLFC) exploits redundancies in the light field images by constructing a tree structure. The top level (root) of the tree captures the common high-level details across the LFI, and other levels (children) of the tree capture specific low-level details of the LFI. Our decompressing algorithm corresponds to tree traversal operations and gathers the values stored at different levels of the tree. Furthermore, we use bounded integer sequence encoding which provides random access and fast hardware decoding for compressing the blocks of children of the tree. We have evaluated our method for 4D two-plane parameterized light fields. The compression rates vary from 0.08 - 2.5 bits per pixel (bpp), resulting in compression ratios of around 200:1 to 20:1 for a PSNR quality of 40 to 50 dB. The decompression times for decoding the blocks of LFI are 1 - 3 microseconds per channel on an NVIDIA GTX-960 and we can render new views with a resolution of 512X512 at 200 fps. Our overall scheme is simple to implement and involves only bit manipulations and integer arithmetic operations.Comment: Accepted for publication at Symposium on Interactive 3D Graphics and Games (I3D '19

An hybrid ensemble based approach for process parameter estimation in offshore oil platforms

International audienceThe valve flow coefficient is commonly used as a parameter to assess the erosion state of choke valves in offshore oil platforms. In particular, the difference between the theoretical value of the valve flow coefficient and its actual value calculated during operation is retained as the valve health indicator. The actual valve flow coefficient is analytically calculated from the oil, water and gas mass flow rates. These quantities, which are allocated on a daily basis based on the measured total production from a number of wells, on physical parameters (pressures and temperatures) related to the specific well, and on a physical model of the process, can be affected by large uncertainties. Based on such values, the evaluation of the health indicator becomes unreliable and undermines the possibility of using it for prognostic purposes. Similar situations arise every time health monitoring rely on unreliable measurement taken by sensors subject to hard working condition, as often happen in the nuclear industry. This paper proposes a method to obtain more accurate daily estimates of the actual values of the oil, water and gas flow rates, from which improved estimates of the flow coefficient will follow. In this respect, an hybrid ensemble aggregating the physical model with data-driven models built using the Kernel Regression (KR) method has been used. Ensemble diversity is ensured by using different training sets;a local procedure based on the historical performance of the models is adopted to aggregate their predictions. The method is verified on real measurements performed on a number of similar offshore choke valves

Validity of a pictorial perceived exertion scale for effort estimation and effort production during stepping exercise in adolescent children

This is the author's PDF version of an article published in European Physical Education Review ©2002. The definitive version is available at http://epe.sagepub.com.Recent developments in the study of paediatric effort perception have continued to emphasise the importance of child-specific rating scales. The purpose of this study was to examine the validity of an illustrated 1 – 10 perceived exertion scale; the Pictorial Children’s Effort Rating Table (PCERT). 4 class groups comprising 104 children; 27 boys and 29 girls, aged 12.1±0.3 years and 26 boys, 22 girls, aged 15.3±0.2 years were selected from two schools and participated in the initial development of the PCERT. Subsequently, 48 of these children, 12 boys and 12 girls from each age group were randomly selected to participate in the PCERT validation study. Exercise trials were divided into 2 phases and took place 7 to 10 days apart. During phase 1, children completed 5 x 3-minute incremental stepping exercise bouts interspersed with 2-minute recovery periods. Heart rate (HR) and ratings of exertion were recorded during the final 15 s of each exercise bout. In phase 2 the children were asked to regulate their exercising effort during 4 x 4-minute bouts of stepping so that it matched randomly prescribed PCERT levels (3, 5, 7 and 9). Analysis of data from Phase 1 yielded significant (P<0.01) relationships between perceived and objective (HR) effort measures for girls. In addition, the main effects of exercise intensity on perceived exertion and HR were significant (P<0.01); perceived exertion increased as exercise intensity increased and this was reflected in simultaneous significant rises in HR. During phase 2, HR and estimated power output (POapprox) produced at each of the four prescribed effort levels were significantly different (P<0.01). The children in this study were able to discriminate between 4 different exercise intensities and regulate their exercise intensity according to 4 prescribed levels of perceived exertion. In seeking to contribute towards children’s recommended physical activity levels and helping them understand how to self-regulate their activity, the application of the PCERT within the context of physical education is a desirable direction for future research

Induced abortion on demand and birth rate in Sami-speaking municipalities and a control group in Finnmark, Norway

Objectives. The objective of this study was to analyze the birth and induced abortion on demand (IAD) rate among women in Sami-speaking communities and a control group in Finnmark County, Norway. Methods. The 6 northern municipalities included in the administration area of the Sami language law (study group) were matched with a control group of 9 municipalities. Population data (numbers, sex and age) were accessed from Statistics Norway. Data on birth rate and IAD during the time period 1999&#x2013;2009 were derived from the Medical Birth Registry (MBR) of Norway. Data on number of women in fertile age (15&#x2013;44 years) were obtained from Statistics Norway. Between 2001 and 2008, this age group was reduced by 12% (Sami) and 23% (controls), respectively. Results. Finnmark County has a high IAD rate and 1 in 4 pregnancies (spontaneous abortions excluded) ended in IAD in the study and control groups. The total fertility rate per woman was 1.94 and 1.87 births, respectively. There was no difference between groups with regard to the IAD/birth ratio (P=0.94) or general fertility rate GFR (P=0.82). Conclusions. Women in the Sami-majority area and a control group in Finnmark County experienced a similar frequency of IAD and fertility rate

Toddlers’ childcare stress across context and time: A cross-sectional and longitudinal investigation of children’s cortisol levels during transition, in childcare, and at home - and their relation to childcare, child, and family factors

Sammendrag Små barns barnehagestress på tvers av kontekst og tid Hjernen er under rask utvikling i barns første leveår og i denne perioden dannes et livslangt helsegrunnlag. I Norge går nesten alle ett- og toåringer i barnehagen og det er derfor viktig å skaffe til veie mer kunnskap om hvordan de har det i barnehagen. Det er funnet at små barn har et forhøyet nivå av stresshormonet kortisol i barnehagen. Dette er et fenomen vi trenger mer forskning på. Det er for eksempel uklart hvilken type stress dette er, i hvilken grad den er begrenset til barnehagekonteksten, og hvordan den utvikler seg over tid. Kortisol, målt i spytt, er en anerkjent indikator på opplevd stress. Å undersøke små barns kortisolnivå kan bidra til økt forståelse av hvordan de opplever barnehagen, hvilke barn som er mest utsatt for barnehagestress og sammenhenger mellom barnehagekvalitet og stress. I studiene som inngår i denne avhandlingen er små barns kortisolnivå undersøkt, både på tvers av kontekster (i barnehagen og hjemme) og over tid (fra tilvenningen og gjennom et helt barnehageår), samt at det er sett på hvordan endringer av stressnivå henger sammen med kjennetegn ved barnet, familien og barnehagen. For å måle endringer av barnas kortisolnivå, ble det tatt spyttprøver av 320 barn ved til sammen 30 anledninger, om morgen, ettermiddagen og kvelden under tilvenningen til barnehagen og i starten, midten og slutten av et barnehageår. I tillegg ga spørreskjemaer og observasjoner informasjon om blant annet barnas temperament og trivsel i barnehagen, samt barnehagekvalitet. Lineære blandete effektmodeller ble brukt i de statistiske analysene. Barna hadde et forhøyet stressnivå på alle ettermiddagsmålinger i barnehagen, mens de hadde et lavt stressnivå på kvelden hjemme og både på ettermiddag og kveld på helgedager hjemme. Funnene indikerer at barna opplevede barnehagen og hjemmet forskjellig og at lav barnehagekvalitet forsterket denne forskjellen: Barna var mer stresset i avdelinger med flere enn tre barn per voksen og i avdelinger som hadde mindre forutsigbare rammer. Under tilvenningen til barnehagen hadde stressnivået et kurvlineært mønster. Barna hadde et lavt stressnivå så lenge foreldrene var til stede sammen med dem i barnehagen, mens de var tydelig stresset den første uken de var adskilt fra foreldrene. Etter cirka en måned i barnehagen hadde stressnivået falt til et lavere nivå, men var fortsatt noe forhøyet. De aller yngste barna hadde et høyere stressnivå ved dette tidspunktet. Barna ble fulgt videre gjennom barnehageåret og i gjennomsnitt så det ut som om de akkumulerte noe stress over tid ved at de viste stigende nivåer av morgen- og kveldskortisol. Dette langsiktige stressmønsteret delte seg i to profiler i henhold til trivsel i barnehagen: Barn med veldig høy trivsel viste tegn til å gradvis falle mer til ro i barnehagen mens barn med lavere trivsel hadde et høyere og stigende stressnivå over tid og så dermed ut til å bli mer stresset gjennom året. Barnehagekonteksten så ut til å være mer krevende enn hjemmet for barna og dette kan tyde på at barnehagepraksis ikke er ideelt tilpasset til de minste barnas forutsetninger og behov. Våre funn indikerer at en forsvarlig bemanning av minst en voksen per tre barn gjennom hele åpningstiden, stabile og forutsigbare rutiner, rolige ettermiddager, og oppmerksomhet på de aller yngste barna, samt fysisk passive barn, er viktig for barnas stressregulering gjennom barnehageåret. Stressmønsteret som ble observert under tilvenningen peker på hvor viktig foreldres involvering i overgangen fra hjem til barnehage er, og at de aller yngste barn trenger mer tid til å falle til ro i barnehagen. Barna så ut til å ha en forskjellig tilpasning til barnehagen gjennom året, basert på hvordan ansatte vurderte deres trivsel. Mekanismene bak dette funnet er vanskelig å vurdere, men med støtte fra tidligere forskning er det rimelig å påstå at ansatte må se og inkludere barn som er tilbaketrukne og lett blir oppskaket, samt de som vurderes til å ikke trives, og tilrettelegge for godt samspill mellom voksne og barn og barna imellom. Det vurderes at det stressnivået som er observert i denne avhandlingen, er moderat og tidsbegrenset, men at det samtidig skjedde noe stressakkumulering hos barna gjennom barnehageåret. Siden stressnivået viste seg å henge sammen med lavere trivsel og lavere barnehagekvalitet, konkluderes det at dette ikke utelukkende representerer såkalt positivt stress. Framtidig forskning bør blant annet undersøke barnehagestress i et langtidsperspektiv nærmere, samt dens effekter, og hvordan dyadisk samspill med voksne kan regulere barnas stressnivå.Abstract Toddlerhood is a stage of rapid brain development, during which the foundation for a life-long health trajectory is built. With a large and increasing share of young children attending out-of-home childcare, it is vital to know how they are faring in this context. Toddlers have been observed to have elevated levels of the stress hormone cortisol in childcare and this phenomenon needs to be understood better. It is unclear which type of stress the observed cortisol elevations constitute and whether these elevations are limited to the childcare environment, and how they develop over time. Cortisol is recognized as marker of perceived stress and can give us an indication of children’s experience in childcare. Investigating the link between cortisol levels and child and family characteristics as well as childcare quality can help us to determine if there are groups of children who are more prone to stress in childcare and if there are childcare practices which may trigger or alleviate stress. These insights could help us to better adjust childcare practice to toddlers’ needs. The studies included in this thesis have measured young children's cortisol levels both cross-sectionally (in childcare and at home) and longitudinally (starting from the transition to childcare and throughout a year in childcare) and examined how stress levels were linked to child, family, and childcare factors. Saliva samples were collected from 320 children in the morning, afternoon, and evening during the initial transition to childcare and at the beginning, middle, and end of a year in childcare and analyzed for cortisol. Parents and caregivers respectively filled questionnaires on age, gender, temperament, number of siblings, childcare quantity, and maternal education, as well as group size, the number of caregivers and pedagogues among the caregivers, children’s well-being in childcare, and organizational flow in group units. In addition, interactional quality was observed. Linear mixed models were applied for statistical analysis. Children had elevated cortisol levels in the afternoon in childcare on every measurement occasion. However, cortisol levels were distinctly sinking towards the evening and on weekend days at home. The childcare context seemed to be more demanding than the home context for the children in our studies. Lower childcare quality exacerbated this difference: Children had higher cortisol levels in childcare when they were attending group units with more than three children per caregiver and a higher degree of disorganization. Our cross-sectional investigation indicated that childcare practice may have not fully matched to the needs of toddlers. A sufficient caregiver availability, stable and predictable routines, quiet afternoons, and a focus on young and passive children are likely highly important for stress regulation. The longitudinal investigation started from one-year-olds’ initial transition to childcare. Cortisol levels followed a curve-linear pattern during transition, with low levels on days with parents present, high levels in the first week separated from parents and comparably lower levels after a month of childcare attendance. Acclimatization days with parents likely offered an important time window to familiarize children with the childcare environment. The youngest children had higher afternoon cortisol levels after a month in childcare and may have needed longer time to settle in at childcare. The investigation continued through a year in childcare, and, on average, it seemed that children accumulated some stress throughout the year as indicated by increasing evening and morning cortisol levels. This longitudinal stress pattern split into two profiles according to children’s well-being in childcare: Children with very high well-being showed a decrease in afternoon cortisol elevations while other children had higher overall cortisol levels and increasing morning and evening cortisol levels throughout the year and thus showed more distinct signs of a stress accumulation. Hence, children seemed to follow different patterns of long-term adaption to childcare based on their well-being. The mechanisms behind this finding are difficult to assess, but with support from previous research, it is reasonable to assert that caregivers must see and include children who are withdrawn or easily upset, as well as those they assess as not thriving. The observed stress was likely moderate and time-limited, yet there was some long-term stress accumulation. Since stress was associated with lower well-being and aspects of lower childcare quality, it is concluded that cortisol elevations in childcare do not merely represent positive stress. Future research must examine childcare stress in a longitudinal perspective, as well as its effects, and how dyadic interactions with caregivers can regulate children's stress levels

Parametric Generation of Polygonal Tree Models for Rendering on Tessellation-Enabled Hardware

The main contribution of this thesis is a parametric method for generation of single-mesh polygonal tree models that follow natural rules as indicated by da Vinci in his notebooks. Following these rules allow for a relatively simple scheme of connecting branches to parent branches. Proper branch connection is a requirement for gaining the benefits of subdivision. Techniques for proper texture coordinate generation and subdivision are also explored.The result is a tree model generation scheme resulting in single polygonal meshes susceptible to various subdivision methods, with a Catmull-Clark approximation method as the evaluated example.As realistic visualization of tree models is the overall objective, foliage appearance and the impression of a dense branching structure is considered. A shader-based method for accurately faking high branch density at a distance is explored

Real-Time Data-Driven Drilling Optimization

Drilling a well for exploration or production of petroleum resources is a costly and complicated procedure. There is a great potential for cost reduction by drilling safer, faster and with less Non-Productive Time (NPT). Reducing the time spent on drilling will not only save costs, it also provides the benefit of lowering the environmental impact of drilling operations. From a mechanical standpoint, achieving high efficiency drilling can be realized by optimizing the applied Weight on Bit (WOB) and drillstring rotational speed (Revolutions per Minute - RPM). However, selection of optimal values for WOB and RPM is a complex task. The drilling action at the bit happens at distances often several kilometers away from the rig, and only indirect measurements performed at the surface are routinely available to gauge what is happening down the hole. The task is further complicated by uncontrollable changes in downhole conditions such as variations in rock properties and wear and tear on the bit, which can alter the bit/rock interaction so that the WOB and RPM that was optimal a few minutes ago might no longer be the most efficient solution. Furthermore, the information required to accurately model the downhole conditions might not be directly measurable or available in real-time, which could preclude available models from predicting the optimal WOB and RPM. In this work, an adaptive model-free algorithm called Extremum Seeking (ES) is investigated for the purpose of optimizing the WOB and RPM in real-time. The method is data-driven and relies on continuously performing small tests with the applied WOB and RPM while drilling ahead, to gather information about the current downhole conditions. The test results are used to generate a local linear model, based on which the ES algorithm continuously performs automatic adjustments in WOB and RPM in the direction that increases Rate of Penetration (ROP) or reduces Mechanical Specific Energy (MSE). This process is designed to iteratively drive the WOB and RPM to their optimal values and maintain optimal drilling by adapting to changes in downhole conditions. The ES method does not require an a priori model of the drilling process and can thus be applied even in instances when sufficiently accurate drilling models are not available. To ensure that the ES algorithm does not steer the WOB or RPM to values which might be detrimental to drilling equipment or personnel, several constraint handling techniques are included in the proposed methodology. The ES algorithm employed in this thesis is a product of modifications proposed by the authors, as well as different algorithms and tools found in the literature, which are assembled to make the routine better suited for drilling applications. The outlined optimization strategy is tested in a variety of scenarios with simulations and experiments on a small-scale drilling rig. The experiments and simulations demonstrate the ES algorithm’s ability to seek out optimal values for WOB and RPM, adapt to changes in downhole conditions, and avoid violation of process constraints. Therefore, this study indicates a potential for significant improvement in drilling efficiency from applying the ES method for real-time drilling optimization