Spelling suggestions: "subject:"miljöteknik"" "subject:"energiteknikk""
81 |
En studie av mekanismene bak telehiving. / A Study on Mechanisms of Frost Heave.Hinna, Åshild January 2012 (has links)
Telehivskader er et stort problem på norske veger. Senest i fjor vinter ble flere nye norske motorveger ødelagt av telehiv. Siden hele vegkroppen må graves opp og bygges på ny for å få bukt med telehivskadene, medfører dette store økonomiske kostnader som burde vært unngått. Denne oppgaven ser nærmere på telehivproblemet. Teorien bak problemet er belyst i første del av oppgaven. Den inkluderer de tre forutsetningene for at telehiv skapes: vann, frost og telefarlige materialer. Det er sett på forhold ved topografi og drenering som kan skape problemer, hva som skjer i frysefronten, den termiske prosessen som foregår der, samt hvordan dannelsen av islinser foregår.Frostmengder brukes til å dimensjonere frostsikring av veger. Ved beregning av frostmengder er det ulik praksis i estimeringen av frostmengder. Man kan enten bruke døgnmiddelverdier eller månedsmiddelverdier for lufttemperaturen i beregningen. På bakgrunn av dette er det utført beregninger av frostmengde F5 og F10 for ti ulike målestasjoner i Norge både ved bruk av måneds- og døgntemperaturer. Det ble funnet en forskjell i frostmengde mellom de to metodene på cirka 2000 hoC mindre frostmengde ved bruk av månedstemperatur enn ved døgntemperaturer. Dermed vil dimensjonering etter døgntemperatur gi et dypere frostsikringslag enn dimensjonering etter månedstemperatur. Malvikvegen, fylkesveg 950, har tidligere hatt noe ujevnheter grunnet telehiv. Strekningen er derfor nærmere undersøkt i denne oppgaven. For å studere telehiv direkte i felt er det utført høydemålinger med nivellement gjennom vinteren på to steder på strekningen. På denne måten kan eventuelle hevelser i grunnen som følge av telehiv og tilbaketrekning av telehivet i teleløsningen registreres. Forholdene i grunnen på denne strekningen er kartlagt med georadar for å få oversikt over eventuelle islinser, telefronten og en grov materialkarakteristikk. Selbuvegen, fylkesveg 963, er en annen strekning der det er store problemer med telehiv, både i form av ujevnheter og sprekkedannelser på overflaten. Det er derfor utført oppgraving og uttak av materialprøver i ulike dybder for å undersøke denne strekningen. Prøvene er undersøkt i laboratoriet med blant annet direkte telehivforsøk.Oppgraving av materialprøver er også utført på Malvikvegen. Ved oppgraving er grunnforholdene analysert og materialprøver tatt i ulike dybder for videre analyse i laboratoriet. I laboratoriet er det utført sikteanalyse, direkte telehivforsøk og glødetapstest på materialet. Det er også utført Coulteranalyse for å finne finstoffgraderingen til materialene. Materialets telefare er vurdert på bakgrunn av de ulike forsøkene og ulike klassifiseringssystem. Telehivforsøk viste teleskytende evne middels for alle de fire prøvene, selv om maks-døgn med telehiv og vannopptak viste store forskjeller. Prøvene fra Selbuvegen er de som har høyest maks-døgn med telehiv og høyest vannopptak. Dette samsvarer med observasjoner i felt, da denne vegen har mest telehivskader av de to vegene.
|
82 |
Wind-induced Dynamic Response and Aeroelastic Stability of a Suspension Bridge crossing SognefjordenOdden, Trine Hollerud, Skyvulstad, Henrik January 2012 (has links)
This thesis is a feasibility study, with regards to aerodynamic stability, about the possibility of constructing a suspension bridge with a main span of 3700m over the Sogne Fjord in Norway. The design wind velocity for the Sogne Bridge is 64.2 m/s. A preliminary design is conducted to find the approximate dimensions for the bridge models with different cross sections. These bridges are then modeled in Abaqus in order to find the natural frequencies, vibration modes and mass properties. The key to calculating the critical velocity of the models is to include the aerodynamic derivatives of the cross sections. A Matlab program has the aerodynamic derivatives, natural frequencies, vibration modes and mass properties as input. With this information the program is able to calculate the multimode flutter velocity of the models. Also, a response calculation is executed in order to see how the different models behave under serviceability wind velocity. This gives a better picture of which models are most applicable. The results show that to apply a slotted box girder improves the flutter velocity, and all the models with this type of cross-section have a stability limit above the design velocity. For a single box girder, the structural measure of using a mono-cable instead of the traditional two-cable bridge geometry increases the critical wind velocity to above the design velocity. All the models satisfy the serviceability response requirements.
|
83 |
Analytisk brannprosjektering med simulering : Alternativ røykventilering i Alabasterhallen i det nye Nasjonalmuseet / Analytic Fire Design with Simulation : Alternative Smoke Ventilation in Alabasterhallen in the New National MuseumLarsen, Maiken, Tøndevold, Nina January 2012 (has links)
Oppgaven tar for seg Alabasterhallen i det nye Nasjonalmuseet på Vestbanen i Oslo. Dette er en utstillingshall som per dags dato er under prosjektering. Det er undersøkt hvordan en alternativ røykventilasjonsløsning vil fungere. Løsningen er arkitektønsket og består av 20 cm brede slisser i himling nær yttervegg som røyken skal bevege seg gjennom for deretter å trekkes videre ut av avtrekksluker eller -vifter i tak. Den alternative løsningen er vurdert opp mot en tradisjonell termisk røykventilasjonsløsning dimensjonert etter Melding HO-3/2000 Temaveiledning Røykventilasjon. Den tradisjonelle løsningen består kun av avtrekks- og tilluftsluker. Rapporten består av et litteraturstudie, en kvalitativ- og en kvantitativ analyse. Litteraturstudiet inkluderer teori om brannprosjektering, regelverk, røyk, røykventilasjon og CFD-simulering.I den kvalitative analysen er brannscenarioer fastsatt på bakgrunn av befaringer på museer, informasjon funnet gjennom litteraturstudiet og brann¬statistikk. To brann-scenarioer ble valgt for videre kvantitativ analyse.I den kvantitative analysen er den alternative røykventilasjonsløsningen vurdert ved bruk av CFD-programmet FDS. Det er også foretatt en evakueringssimulering i Pathfinder. Dette er gjort for å kunne sammenligne nødvendig rømningstid, funnet i Pathfinder, med tilgjengelig rømningstid funnet fra brannsimuleringene.De ulike røykventilasjonsløsningene er sammenlignet med hverandre, og i tillegg vurdert opp mot tålegrenser for evakuering gitt i NS 3901:1998 Risikoanalyse av brann i byggverk og HO-meldingen.Følgende anbefalinger er gitt i oppgaven:- Alternativ røykventilasjonsløsning med slisser, avtrekksvifter i tak og tilluftsvifter i fasade bør benyttes i Alabasterhallen.- Det bør benyttes røykskjermer som er dimensjonert for å hindre at røyken synker og spres på undersiden av skjermene, og som kan aktiveres avhengig av brannens plassering.- Det bør benyttes røykseksjonering over himling for å unngå at røyken sprer seg på oversiden og trekker ned i de andre delene av hallen. Dette vil også kunne hindre sotlegging av hele himlingen.
|
84 |
Capacity Assessment of Titanium Pipes Subjected to Bending and External PressureBjørset, Arve January 2000 (has links)
<p>Exploration for oil and gas is moving towards deeper waters. Steel has been the most common riser material. Related to deep water concepts titanium has become an alternative to steel for these applications.</p><p>Several codes exist today for predicting collapse loads for marine pipes. However, the capacity formulas are developed for steel. If the formulas are applied directly to titanium several parameter uncertainties will be unknown. Ideally, extensive model testing of titanium pipes is required. This thesis discusses and investigates utilisation of experimental material test data and a supplementary numerical approach based on finite element analysis. The relationship between material model parameters as input to the analysis and the collapse capacity is investigated by performing a series of nonlinear FEM analyses.</p><p>Statistical models for the input material model parameters are established based on tests on small specimens cut from titanium pipes. These models are subsequently combined with results from the FEM analyses by application of response surface methods. As output from the analysis, the probability distributions of the pipe capacity with respect to local buckling/collapse are obtained.</p><p>Finally, the data from the nonlinear finite element analyses are compared to a relevant design code. Suggestions for a possible basis for design formulas to check for the local collapse capacity of deep water titanium risers are provided.</p>
|
85 |
Statistical modelling of pipe failures in water networksRøstum, Jon January 2000 (has links)
<p>This thesis presents an evaluation of statistical methods for modelling pipe failures for each individual pipe in a water distribution network. This thesis introduces the Non Homogeneous Poisson Process (NHPP) with covariates (i.e. explanatory variables) as an appropriate method for modelling pipe failures in water networks. As part of this research, a computer program has been developed that estimates the parameters in the NHPP (“Power law” model). The results from this NHPP model are compared to the results obtained from a modified Weibull Proportional Hazards Model (PHM), where the hazard function is allowed to continue beyond the pipe’s first failure. The models are applied in a case study using data for the water distribution network in Trondheim, Norway.</p><p>The statistical models have been calibrated, verified and used to predict failures for both networks (i.e. group of pipes) and individual pipes. Covariates that have a significant influence on the rate of occurrence of failures (ROCOF) are documented. Based on the results from the case study, NHPP is recommend over the Weibull PHM for modelling failures in water networks.</p><p>The output from the statistical models can be used for a variety of purposes in water network management. In the long term the models can be used to estimate future budget needs for rehabilitation. In the short term the models can be used to define candidates for replacement based on poor structural condition. Information about failure intensity is also required for carrying out network reliability analysis. For this purpose reliability data for each individual pipe is required, which is exactly what the predictive models described in this thesis provide.</p>
|
86 |
Hard Rock Tunnel BoringBruland, Amund January 2000 (has links)
<p>The main purpose of the thesis work has been to improve the existing prediction models and to provide a toolbox for the TBM tunnelling industry (project owners, consultants, contractors, manufacturers, etc.) to be used through all phases of a project:</p><p>• Preliminary and feasibility studies</p><p>• Project design and optimisation</p><p>• Site investigations</p><p>• Tendering and contract</p><p>• Construction</p><p>• Possible disputes or claims.</p><p>The various reports of the thesis treat various subjects of TBM tunnelling. Combined with other estimation models published in the Project Report Series from the Department of Building and Construction Engineering, the reports of the thesis provides a reliable and practical tool to be used for:</p><p>• Estimating net penetration rate and cutter life</p><p>• Estimating construction time and costs, including risk or uncertainty</p><p>• Assessing risk with regard to deviation or variation in estimated rock mass boreability, machine parameters and tunnelling performance</p><p>• Designing auxiliary systems such as ventilation, muck transport, etc.</p><p>• Establishing and managing price regulation in contracts</p><p>• Verifying machine performance</p><p>• Back-mapping and verification of the geological conditions</p><p>• Collecting, normalising and analysing of rock samples, machine performance data and cutter wear data.</p><p>The thesis work has not been focused on basic principles, theoretical modelling or laboratory experiments of rock cutting with disc cutters, although observations and results from field studies are presented and analysed in [11]. Several other researchers and institutions have covered those topics. To be mentioned here is the prominent and comprehensive research done at Colorado School of Mines in the USA and at Luleå University of Technology in Sweden. Both institutions have a series of publications ranging over three decades in this area.</p> / This thesis consists of 10 volumes. Only volume one is available for download. See http://www.tunnel.no/ for more information or contact the author: amund.bruland at ntnu.no
|
87 |
Capacity Assessment of Titanium Pipes Subjected to Bending and External PressureBjørset, Arve January 2000 (has links)
Exploration for oil and gas is moving towards deeper waters. Steel has been the most common riser material. Related to deep water concepts titanium has become an alternative to steel for these applications. Several codes exist today for predicting collapse loads for marine pipes. However, the capacity formulas are developed for steel. If the formulas are applied directly to titanium several parameter uncertainties will be unknown. Ideally, extensive model testing of titanium pipes is required. This thesis discusses and investigates utilisation of experimental material test data and a supplementary numerical approach based on finite element analysis. The relationship between material model parameters as input to the analysis and the collapse capacity is investigated by performing a series of nonlinear FEM analyses. Statistical models for the input material model parameters are established based on tests on small specimens cut from titanium pipes. These models are subsequently combined with results from the FEM analyses by application of response surface methods. As output from the analysis, the probability distributions of the pipe capacity with respect to local buckling/collapse are obtained. Finally, the data from the nonlinear finite element analyses are compared to a relevant design code. Suggestions for a possible basis for design formulas to check for the local collapse capacity of deep water titanium risers are provided.
|
88 |
Statistical modelling of pipe failures in water networksRøstum, Jon January 2000 (has links)
This thesis presents an evaluation of statistical methods for modelling pipe failures for each individual pipe in a water distribution network. This thesis introduces the Non Homogeneous Poisson Process (NHPP) with covariates (i.e. explanatory variables) as an appropriate method for modelling pipe failures in water networks. As part of this research, a computer program has been developed that estimates the parameters in the NHPP (“Power law” model). The results from this NHPP model are compared to the results obtained from a modified Weibull Proportional Hazards Model (PHM), where the hazard function is allowed to continue beyond the pipe’s first failure. The models are applied in a case study using data for the water distribution network in Trondheim, Norway. The statistical models have been calibrated, verified and used to predict failures for both networks (i.e. group of pipes) and individual pipes. Covariates that have a significant influence on the rate of occurrence of failures (ROCOF) are documented. Based on the results from the case study, NHPP is recommend over the Weibull PHM for modelling failures in water networks. The output from the statistical models can be used for a variety of purposes in water network management. In the long term the models can be used to estimate future budget needs for rehabilitation. In the short term the models can be used to define candidates for replacement based on poor structural condition. Information about failure intensity is also required for carrying out network reliability analysis. For this purpose reliability data for each individual pipe is required, which is exactly what the predictive models described in this thesis provide.
|
89 |
Hard Rock Tunnel BoringBruland, Amund January 2000 (has links)
The main purpose of the thesis work has been to improve the existing prediction models and to provide a toolbox for the TBM tunnelling industry (project owners, consultants, contractors, manufacturers, etc.) to be used through all phases of a project: • Preliminary and feasibility studies • Project design and optimisation • Site investigations • Tendering and contract • Construction • Possible disputes or claims. The various reports of the thesis treat various subjects of TBM tunnelling. Combined with other estimation models published in the Project Report Series from the Department of Building and Construction Engineering, the reports of the thesis provides a reliable and practical tool to be used for: • Estimating net penetration rate and cutter life • Estimating construction time and costs, including risk or uncertainty • Assessing risk with regard to deviation or variation in estimated rock mass boreability, machine parameters and tunnelling performance • Designing auxiliary systems such as ventilation, muck transport, etc. • Establishing and managing price regulation in contracts • Verifying machine performance • Back-mapping and verification of the geological conditions • Collecting, normalising and analysing of rock samples, machine performance data and cutter wear data. The thesis work has not been focused on basic principles, theoretical modelling or laboratory experiments of rock cutting with disc cutters, although observations and results from field studies are presented and analysed in [11]. Several other researchers and institutions have covered those topics. To be mentioned here is the prominent and comprehensive research done at Colorado School of Mines in the USA and at Luleå University of Technology in Sweden. Both institutions have a series of publications ranging over three decades in this area. / This thesis consists of 10 volumes. Only volume one is available for download. See http://www.tunnel.no/ for more information or contact the author: amund.bruland at ntnu.no
|
90 |
Impact on Duplex Steel Pipes with Precipitated Sigma-phase : Modeling a Full-scale Impact Test on Pipe FittingsBratlie, Andreas, Hillestad, Christian Bergstrøm January 2012 (has links)
Duplex stainless steel (DSS) is a common material in offshore pipe fittings. A manufacturing defect has altered the behavior of the components through an erroneous heat treatment, which has led to precipitation of &#120590;-phase. A report showing a strong correlation between precipitated &#120590;-phase and the reduction in impact toughness, initiated a great interest in the offshore industry for further studies of the effect of precipitated &#120590;-phase in DSS pipe fittings. In this thesis a numerical approach to simulate the behavior of duplex stainless steel with precipitated &#120590;-phase has been performed. The simulations have been done using the Gurson material model, which is implemented in the user defined material model in the SIMLab Metal Model. In addition the material model has been combined with a brittle fracture criterion. The results deviate from the observations done in the laboratory. The reasons for the deviations were found to be quite complex, but effects from mesh sensitivity and incorrect material optimization was found. The influence of the Gurson model is limited for the specimens acting in a brittle manner. It is therefore considered unnecessary to apply this material model for these problems.
|
Page generated in 0.0536 seconds