79 research outputs found
The impact of economic abuse on depressive symptoms among survivors of intimate partner violence
No full textThis dissertation examined the impact of economic abuse and the mediating role of economic self-efficacy on depressive symptoms among survivors of intimate partner violence (IPV). The primary research question aimed to examine the associations between economic abuse experiences and depressive symptoms from a cross-sectional and longitudinal viewpoint, among a sample of 457 female survivors of IPV, recruited from 14 domestic violence programs, across 10 states and Puerto Rico. The secondary research question aimed to examine the mediating role of economic self-efficacy in the relationship between economic abuse and depressive symptoms. This dissertation theorized that higher levels of economic abuse experiences would relate to increased levels of depressive symptoms. Stress theory (Thoits, 2010) was utilized to provide a framework for understanding the way the stress of economic abuse and the accumulated life strain, which occurred from financial dependence on an abuser, might converge to produce high levels of stress and depression for survivors of IPV. Furthermore, this dissertation theorized that economic self-efficacy would mediate the relationship between economic abuse experiences and depressive symptoms. The concept of self-efficacy evolved from social learning theory (Bandura, 1994, 1997, 2008) and examined how the survivor’s perceived economic competence, during or following the economic abuse experiences, provided a specific mediating construction in the development of depressive symptoms. The findings revealed that, from a cross-sectional perspective, higher levels of economic abuse experiences related to higher levels of depressive symptoms; however, this relationship was not mediated by economic self-efficacy. Furthermore, from a longitudinal, 14-month perspective, there was no significant impact of the change in economic abuse experiences on the change in depressive symptoms. In examining the impact of economic abuse on depressive symptoms among survivors of IPV, this study added to the knowledge base of the social sciences, furthered understanding of the impact of economic abuse and the possible mediating impact of economic self-efficacy, and provided critical information that the field of IPV could utilize in developing programs and policies to support survivors.Ph.D.Includes bibliographical referencesby Amanda Mathisen Styliano
Seismic performance of an innovative dissipative replaceable components bracing steel frame (DRBrC)
No full textThe structural performance of a steel Concentrically Braced Frame (CBF) equipped with replaceable dissipative seismic components, called DRBrC, is presented. X-diagonal CBFs are an efficient structural solution for buildings in seismic prone areas, being conceived to dissipate the energy stored during the earthquake through plastic deformation of bracing elements; all the other components remain in the elastic field thanks to opportune design criteria. Of course, structural damages, even if voluntarily located in specific regions, need to be repaired after the seismic event to restore the functionality of the building, leading to relevant economic (and time) effort since the full replacement of damaged dissipative components is necessary after irreversible plastic deformations. Recently, research activities have been widely carried out to provide repairability of steel buildings by means of easily replaceable dissipative components. The Research Fund for Coal and Steel (RFCS) of European Commission, for instance, promoted and funded the research project DISSIPABLE - Fully dissipative and easily reparable device for resilient buildings with composite steel-concrete structure”, with the aim of designing, producing, optimizing and testing several dissipative components for steel structures having, as fundamental feature, the full repairability after the earthquake without impacting on other components. In the present paper, the seismic performance of a steel braced frame equipped with a specific typology of dissipative replaceable device at the ends of braces is presented by means of nonlinear analyses
Energioptimalisering og mikrogrid, Granåsen skisenter
No full textGranåsen (ca 1 - 1,3 GWh/år for de siste 5 år) står ovenfor store endringer årene fremover. En
rekke utbyggingsfaser er under planlegging, og første utbyggingsfase pågår allerede.
Utbygningene vil bidra til et høyere energiforbruk (estimert til >6,1 GWh/år) med oftere og
høyere effekttopper. Utbygningene skal følge Trondheims kommunedelplan for energi og klima
for perioden 2017-2030. Kartlegging av laster, installasjon av effektloggere, andre målinger
vedrørende anlegget og litteraturstudie, er utført for å undersøke potensialet for mikrogrid i
Granåsen fra et energi- og økonomisk perspektiv. Et modellerings- og simuleringsverktøy
(HOMER Pro) har blitt brukt til å lage forenklede modeller av Granåsen som mikrogrid.
Resultater fra installerte effektloggere fremstilles i rapporten. De målte lastene inkluderer lys
for langrennsløyper, snøproduksjon, og flomlys ved langrenn og hoppstadion. Måledataen og
vurdering av resultatene har ført til konkrete forslag for energioptimalisering. Mer spesifikt,
erstatte eldre teknologi til smart styring av LED flomlys og mer automatisk snøproduksjon er
blitt anbefalt. Automatisk snøproduksjon vil bidra til å gi større fleksibilitet, redusere timer som
blir brukt på forhåndsarbeid og oppstart av snøproduksjonsenhetene. Loggeutstyr ble installert
i Toppidrettsenteret (en bygning), som bidrar til Granåsen totale energiforbruk på grunn av
oppvarming (størst energisektor).
Flere forenklede modeller er blitt implementert i HOMER Pro. En referansemodell for
anleggets nåværende situasjonen, samt scenarioer med batteri, solcellepanelmodeller eller
kombinasjoner. Modellene inkluderer produksjonen (solcellepaneler) og energilagring
(batterier), da disse er mulige tiltak for Granåsen. Tidligere undersøkelser og planlegging viser
at solcellepaneler kan installeres en rekke steder. Det er usikkerheter tilknyttet
simuleringsresultatene fordi modellene er bygd ved hjelp av parametere, som for eksempel
dagens priser for solcellepaneler og batterier.
Mikrogridmodellen med sol og batteri (NPC: 16 461 810 kr) førte til en høyere livsløpskostnad
sammenlignet med dagens referansemodell (NPC: 9 779 497 kr), men mikrogridmodellen
reduserte energi og effektleddet. Modellen med solcellepaneler og batterilagring kan gi en
kostnadsbesparelse på 9,77 % for energileddet per år og 14,18 % for effektleddet per år. Ifølge
simuleringene kan solcellepanelene levere ca. 115 118 kWh/år. Et fremtidig energibehov ble
estimert. Mikrogridmodellen med fremtidig energibehov (NPC: 88 009 640 kr) førte fortsatt til
en høyere livsløpskostnad sammenlignet med fremtidig referansemodell (NPC: 33 811 020 kr),
men mikrogridmodellen reduserte energi og effektleddet. Modellen med solcellepaneler og
batterilagring for fremtidig behov kan gi en kostnadsbesparelse for energileddet på 16,12 % og
effektleddet med 9,95 % per år. Fra simuleringene kan solcellepanelene levere ca. 1 604 984
kWh/år.
Disse simuleringene inkluderer ikke økonomisk støtte, og modellene er også ulønnsomme.
Investeringene i de ulike modellene er høye. Kraftprisene er lavere om sommeren når solenergi
er mest effektiv. Lavere teknologikostnader, samt økte energikostnader, er nødvendig for å
gjøre solenergi og batterier mer konkurransedyktig i Norge. Mikrogrid i Granåsen bør vurdere
andre tiltak for å redusere energiforbruket, samt bruk av solcellepaneler og mobile
batterisystemer
Noise filtering from a nonlinear system by using AANN
No full textIn order to run a gas turbine, the operator (be it human or
automatic) needs to monitor the conditions of the various
parts inside it. Pressures, temperatures, mass flows,
vibrations, power output. These properties all need to be
controlled in order to run the gas turbine optimally. And
in order for the operator to make the necessary
adjustments, sensors inside the gas turbine are needed to
monitor said properties.
As the industry drives towards higher efficiencies and
lower emissions, the accuracy of these sensor readings
inside the gas turbine become more and more important.
The objective of this thesis then, was to see how this
accuracy could be improved by the use of autoassociative
neural networks (AANN), which is a kind of noise filter.
Sensor readings will not be completely accurate, since
the technology is not perfect. One problem is something
called random noise, meaning sensor measurements that
are scattered randomly close to the exact value. A noise
filter will take these scattered measurements and move
them all closer to the exact value.
It is already known that an AANN can perform this task,
and in this thesis the main objective was to find some
indication of just how effective it is as a noise filter.
In order to measure how effective a noise filter is, one
would ideally need one set of measurements, which are
noisy, and one set of corresponding measurements, which
are not noisy at all (perfect measurements). Checking the
level of noise reduction then would be to first filter the
noisy measurements, and then comparing both the
filtered and noisy measurements to the perfect
measurements.
Such a solution can not be found with real measurements
from a gas turbine, because they are never perfect. But if
the measurements were calculated using thermodynamic
and physics equations, they would not contain noise.
They would be completely theoretical, but they would not
contain noise.
Synthetic measurements like these were generated by the
use of a software which can model gas turbines and
calculate theoretical properties for various theoretical
scenarios. Noise was then added to these noise free
measurements in order to emulate the real gas turbine. And with that, two sets of measurements were available:
One set of noisy measurements, and one set of perfect
measurements.
With the use of the MATLAB neural network toolbox,
these sets of measurements were used to test the
effectiveness of an AANN as a noise filter. The noisy
measurements were filtered through an AANN, and the
filtered and noisy measurements were then compared to
the perfect measurements.
Artificial neural networks (ANN), which also have some
noise filtering abilities, were also tested this way. But not
as extensively as the AANN.
Results showed that there was indeed noise reduction, but
not for all the individual parameters in the measurements.
For some parameters, the AANN achieved very good
noise filtering, but for other parameters there was no
effect.
The reason for this is not entirely clear, but earlier two
purely mathematical examples were tested in order for the
author to familiarize himself with the methodology. And
these examples only had twothree
parameters; few
enough to visualize in graphs (2and
3 dimensional).
In these two examples, there was found a trend which
suggested that an AANN does not filter each parameter
individually, but rather all parameters together as if they
were one.
The author can not prove this, but he speculates the same
principle could apply to measurements that have more
than three parameters as well, which means that an
AANN might not be very ideal for noise filtering of
individual sensors inside a gas turbine.
It the future, it could certainly be interesting to test an
AANN on measurements from a real gas turbine. Several
conditions would need to be met for such a test to prove
useful; like extensive correlations between the different
parameters included, and redundant measurements. But it
is not unreasonable to assume there would be some reduction of noise
Analytic Gradients Based Parametric Optimization using CutFEM
No full textDenne avhandlingen presenterer en metodikk for å beregne analytisk deriverivasjoner
av visse mekaniske egenskaper, for eksempel eksempel stivhetsmatrisen, med hensyn
til parametrene som definerer geometrien, for eksempel høyden på en utkragebjelke.
Beregningen benytter en implementering av den isogeometriske metoden
beskåret finittelementmetode (CutFEM).
Evnen til å beregne analytiske gradienter av egenskaper med hensyn til parametere
er verdifull for gradientbasert optimalisering. Spesielt utforskes scenariet av å
minimere ettergivenhet mens man holder seg til en forutbestemt maksimal materialmengde,
selv om andre muligheter også er bemerket. CutFEM gir fordelen med
et fast bakgrunnsnett som ikke påvirkes av endringer i geometri, noe som gjør det
særskilt egnet for parametrisk optimalisering da det eliminerer behovet for komplekst
nett, og omnettlegging.
Et utkrageraktig plateproblem introduseres hvor parametere beskriver formen til en
glatt funksjon (spesifikt en B-spline) som representerer høyden på en 2D utkragerbjelke.
Alle sidene på platen er rette, bortsett fra den parameteriserte toppen. Målet er
å optimalisere formen på denne glatte funksjonen for å minimere ettergivenhet mot
en punktbelastning plassert i nedre høyre hjørne, samtidig som begrensninger på
det totale arealet er begrenset. Det optimale geometrien ble beregnet både med klassisk
Finittelementmetode (FEM) og CutFEM, som ga lignende, men ikke identiske,
resultater. Noen analyser tyder på at en del av avvikene ville forsvinne hvis en jevnt
fordelt belastning langs den høyre enden ble brukt. De gjenværende avvikene kunne
ikke forklares, likevell synes de oppnådde resultatene til å indikere at for plateproblemet
vurderer CutFEM-implementasjonen buede geometrier som for myke sammenlignet
med når kanter består av rette linjer, og at dette påvirker dens dens vurdering
av hvilken geometri som er optimal.
Til slutt presenteres forslag til forbedringer av de anvendte metodene, med særlig
vekt på å redusere diskontinuiteter og raskere beregninger. Disse forslagene tar hensyn
til hvilke egenskaper som er viktige i sammenheng med optimalisering.This thesis introduces a strategy for finding analytical derivatives of certain mechanical
properties, such as the stiffness matrix, with respect to geometry-defining parameters,
such as the height of a cantilever beam. The calculation uses an implementation
of the isogeometric method known as cut finite element method (CutFEM).
Analytical gradients of properties with respect to parameters are useful for gradientbased
optimisation. In particular, the case where minimising compliance using a
set maximum amount of material is discussed, although other possibilities are also
noted. CutFEM has the advantage of having a fixed background mesh that is independent
of the geometry, which makes it particularly well suited for parametric
optimisation since it requires neither complicated meshing nor re-meshing.
The thesis aims is not to directly describe a general solution to a general CutFEM
implementation, rather it uses a specific minimalist implementation as a foundation
to introduce the necessary concepts in an easy and intuition-based manner. The implementation
flaws and shortcomings are used as examples of pitfalls, thoroughly
discussed, and improvements are suggested.
A sheet problem is introduced where parameters describe the shape of the smooth
function, particularly a B-spline, representing the height of this cantilever. All sides
are straight, except for the parameterised top. The shape of this smooth function
is optimised to minimise compliance against a point load placed at the lower right
corner, with constrictions on the total area. The optimal result was calculated using
classical FEM and CutFEM, with similar but not identical results. Some analysis
suggest that some of the discrepancies likely would disappear if a uniformly distributed
load along the right end was used. The reaming discrepancies could not be
accounted for, and the obtained results seem to indicate that for the sheet problem,
the CutFEM implementation has a slight bias towards evaluating curved geometries
as too soft compared when edges composed of straight lines. This bias does in turn
bias what is considered optimal.
Finlay suggestions for improvement of the schemes used are presented, these take
notes of what important characteristics are important in the context of optimisation.
With particular emphases on reducing discontinues, and quicker calculations
How Experience Transfer and Learning Can Lift Knowledge From Individuals to the Organizational Level
No full textAbstractDuring a field development, huge amounts of data are created and gathered. To what extent is the captured data and knowledge actually reused? Is human knowledge and operational information effectively utilized in future projects and can it be used more efficiently during the development phase or the lifetime of the field?Since 2014-2015, The pilot client has been focussing on implementing a software tool for collecting operational data and engineering experience. By creating a common "knowledge database", the operator makes sure the individual learning in each project is saved and made accessible on a company level. Based on the results recorded on the field development, the pilot client has seen that by standardising the knowledge management process, it is possible to locate features for improvement of effectiveness by minimising human error and ensuring motivation for working with optimisation across the company.Learning across large organisations has always been a great challenge. During a field development a huge amount of data is collected over a longer period. Data comes from several sources in different formats – service companies, rig owners, technology providers, and licence partners. During a field development project, it is natural that the engineering teams want rather to spend time on operational project management than looking for data.Based on the experience from both AGR and the pilot client, offset analysis often means a large portion manual data processing and searching for experiences. Working like this means that human error is not locked out. In addition it is very time-consuming and often creating repeated efforts, leading to non efficient resource usage. In the planning and execution of operations, it is important to learn from past experiences to avoid making the same mistakes several times, and to learn from others' success. Valuable experiences exist in most of the organisations, but are unfortunately often difficult to access for the end user.To address the human element around creating and capturing data, The pilot clienthas focused on standardising the process at the same time prioritising knowledge management and skills development within the field development team.To execute the focus, The pilot client uses software technologies to create a cloud based database of well data and experiences in one place, enabling easy access to visual displays for the user. Experiences are captured through a standardised user interface.The engineering time is now spent on analysing data, not looking for it or if found spending hours on processing it.The software visualises trends and opens window for detecting potential challenges in the project and identify missing data and risk. Similar information can be shared between teams onshore and offshore and information flow enables to map potential for improvement in effectiveness.</jats:p
Airbnb og kortidsutleies påvirkning på boligleiemarkedet: evidens fra Tromsø
No full textTromsø har de siste årene vært preget av en betydelig vekst i internasjonal turisme, hvor reisende kommer for å se nordlys og oppleve det arktiske klimaet. Parallelt med dette opplever byen et stadig mer presset boligmarked, og økende leiepriser. Den økte etterspørselen etter korttidsutleie har ført til en markant økning i antall boliger som tilbys gjennom plattformer som Airbnb. Denne utviklingen har reist spørsmål om hvorvidt korttidsutleie påvirker det tradisjonelle bolig- og leiemarkedet i Tromsø. Formålet med denne oppgaven ble dermed å undersøke i hvilken grad økt Airbnb-aktivitet påvirker leiemarkedet i Tromsø, og hvordan konsekvenser dette har for prisdannelse og boligtilgjengelighet.
Den metodiske tilnærmingen tar for seg omfattende data fra flere kilder, hvor det er benyttet en OLS-regresjon i kombinasjon med deskriptiv statistikk for å estimere effekter av mulige forhold som påvirker leiemarkedet. Resultatene viser at en økning i Airbnb-aktivitet er positivt assosiert med høyere leiepriser i langtidsleiemarkedet. Samtidig finner vi indikasjoner på at det skjer en strukturell omfordeling av utleiebolig fra langtidsleiemarkedet, til korttidsleiemarkedet. Effekten fremstår som signifikant, men moderat i størrelse. Videre byr utredningen på interessante og uventede funn, hvor sekundærboliger er positivt assosiert med leiepriser, noe som er motstridende til teori.
Oppgaven konkluderer med at korttidsutleie gjennom Airbnb har målbare effekter på Tromsøs leiemarked, og at dette særlig kommer til uttrykk gjennom redusert tilbud av langtidsleieboliger og et forsterket press på leieprisene
Airbnb og korttidsutleies påvirkning på boligleiemarkedet: evidens fra Tromsø
No full textSammendrag
Tromsø har de siste årene vært preget av en betydelig vekst i internasjonal turisme, hvor reisende kommer for å se nordlys og oppleve det arktiske klimaet. Parallelt med dette opplever byen et stadig mer presset boligmarked, og økende leiepriser. Den økte etterspørselen etter korttidsutleie har ført til en markant økning i antall boliger som tilbys gjennom plattformer som Airbnb. Denne utviklingen har reist spørsmål om hvorvidt korttidsutleie påvirker det tradisjonelle bolig- og leiemarkedet i Tromsø. Formålet med denne oppgaven ble dermed å undersøke i hvilken grad økt Airbnb-aktivitet påvirker leiemarkedet i Tromsø, og hvordan konsekvenser dette har for prisdannelse og boligtilgjengelighet.
Den metodiske tilnærmingen tar for seg omfattende data fra flere kilder, hvor det er benyttet en OLS-regresjon i kombinasjon med deskriptiv statistikk for å estimere effekter av mulige forhold som påvirker leiemarkedet. Resultatene viser at en økning i Airbnb-aktivitet er positivt assosiert med høyere leiepriser i langtidsleiemarkedet. Samtidig finner vi indikasjoner på at det skjer en strukturell omfordeling av utleiebolig fra langtidsleiemarkedet, til korttidsleiemarkedet. Effekten fremstår som signifikant, men moderat i størrelse. Videre byr utredningen på interessante og uventede funn, hvor sekundærboliger er positivt assosiert med leiepriser, noe som er motstridende til teori.
Oppgaven konkluderer med at korttidsutleie gjennom Airbnb har målbare effekter på Tromsøs leiemarked, og at dette særlig kommer til uttrykk gjennom redusert tilbud av langtidsleieboliger og et forsterket press på leieprisene
Cost Analysis of Plug and Abandonment Operations on the Norwegian Continental Shelf
No full textNorway is one of the world's largest petroleum exporters and has been producing oil and gas for almost 50 years. Many of the petroleum fields are soon reaching their maturity stage where income cannot cover the expenses, and must shut down production. In this process, all associated wells are required to be plugged and abandoned. These operations are expensive, and there is a need for conducting targeted research aimed at reducing the costs associated with plug and abandonment (P&A).
In this thesis we consider 82 currently producing fields and 3308 wellbores on the Norwegian Continental Shelf (NCS). A categorisation of these wellbores was performed by using publicly available information on wellbore statuses in combination with a method for determining the required remaining P&A operations. This information was used to estimate the total costs related to P&A operations for each petroleum field on the NCS. The categorisation, cost estimate and information on forecast production and expenses, formed the basis for the development of three optimisation models and one real options model aimed at conducting cost and planning analyses of P&A operations.
We address this cost analysis of P&A operations holistically by focusing on three different planning levels: strategic, tactical and operational. Our study shows that P&A costs should be included when planning for shut downs and that in general there are incentives for postponing shut downs both due to discount rate benefits and uncertainty in petroleum prices. In addition, we found that collaboration in the planning of multi-well P&A campaigns might be economic desirable compared to planning for these operations for fields and wells independently.
This thesis' main contribution is the development of optimisation models that can be used for several purposes associated with P&A, a subject that up to this point is at best scarcely covered in current literature. We believe that the models could be a good starting point for robust cost analysis and planning tools relevant for different actors in the Norwegian petroleum industry
Cost Analysis of Plug and Abandonment Operations on the Norwegian Continental Shelf
No full textNorway is one of the world's largest petroleum exporters and has been producing oil and gas for almost 50 years. Many of the petroleum fields are soon reaching their maturity stage where income cannot cover the expenses, and must shut down production. In this process, all associated wells are required to be plugged and abandoned. These operations are expensive, and there is a need for conducting targeted research aimed at reducing the costs associated with plug and abandonment (P&A).
In this thesis we consider 82 currently producing fields and 3308 wellbores on the Norwegian Continental Shelf (NCS). A categorisation of these wellbores was performed by using publicly available information on wellbore statuses in combination with a method for determining the required remaining P&A operations. This information was used to estimate the total costs related to P&A operations for each petroleum field on the NCS. The categorisation, cost estimate and information on forecast production and expenses, formed the basis for the development of three optimisation models and one real options model aimed at conducting cost and planning analyses of P&A operations.
We address this cost analysis of P&A operations holistically by focusing on three different planning levels: strategic, tactical and operational. Our study shows that P&A costs should be included when planning for shut downs and that in general there are incentives for postponing shut downs both due to discount rate benefits and uncertainty in petroleum prices. In addition, we found that collaboration in the planning of multi-well P&A campaigns might be economic desirable compared to planning for these operations for fields and wells independently.
This thesis' main contribution is the development of optimisation models that can be used for several purposes associated with P&A, a subject that up to this point is at best scarcely covered in current literature. We believe that the models could be a good starting point for robust cost analysis and planning tools relevant for different actors in the Norwegian petroleum industry
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