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Essential to human life is water. Drinking water, in particular, is of utmost significance for all living creatures including man. An examination of the transmission process of drinking water reveals the high importance of pipe lines. The water pipe lines delivering water today encounter serious problems. Corrosion has caused deterioration in pipe lines, which contributes rust to drinking, a serious water quality problem. In addition, pipe line failures have caused social issues, such as suspension of water supply. This study developed a model to estimate the life expectancy and residual life of a pipe based on the assessment of failure risk in order to evaluate the current failure possibility and predict when the pipe will reach the point of failure. The developed model for estimation of residual life by failure risk was used to assess the failure risk of water pipes based on the general data and pipe sources of the Chang Won City water pipes. The efforts to diagnose and evaluate water pipes are limited to the assessment of current pipe conditions, which is why they can easily determine the priority of rehabilitation based on the current pipe conditions but have hard time getting information about how the pipes have deteriorated to the point of requiring rehabilitation. The objectives of this study are: (1) develop a model for estimating corrosion rates and residual thickness of water pipes, (2) assess loads and stress affecting water pipes, (3) to estimate damage risk, and (4) calculate safety factors. Results of the study could help reduce rehabilitation costs and secure water quality after renovation. Thus it would contribute to the safe and stable operation and management of pipe networks by increasing the life of water pipes.

Aging and leaking water infrastructure wastes water resources and creates public health risks. Upgrading of potable water systems represents a large financial burden for water utilities and private property owners. The conventional approaches of repair, rehabilitation and replacement are very effective, but will take decades to implement even if a financial commitment to do so was made immediately. A novel approach of in-situ remediation of leaks, achieved by harnessing the ability of water or pipe to repair leaks via clogging, could potentially reduce leak rates and extend the lifetime of existing infrastructure at relatively low cost and inconvenience. Physical clogging, precipitation and metallic corrosion were identified as major mechanisms of in-situ leak remediation in potable water pipelines. Autogenous repair (i.e., self-repair without added particles) of small leak-holes (150–"1000 μm) in copper and iron was validated in the laboratory at water pHs of 3.0–11.0, operating water pressures of 20–60 psi, upward and downward leak orientations, and for a range of water chemistries. In bench scale experiments, the time to repair of iron pipe leaks increased with leak size to the power of 0.89–1.89, and decreased with pipe wall thickness to the power of -1.9 to -1.0. The time to repair of copper pipe leaks increased with water pressure to the power of 1.7. Additionally, the waters with a higher DO and corrosivity as measured by RSI, significantly decreased the time to repair of carbon steel 400 μm leaks by 50–70%. The presence of chlorine dioxide significantly increased the fraction of repaired 200 μm copper pipe leaks by 3 times when compared to the control without any disinfectant. In the building scale study, the fraction of repaired iron pipe leaks decreased with the logarithmic leak size with a slope of -0.65 after one-year duration of experiments, while leak orientation and water pressure were not influential in time to or likelihood of repair for iron pipe leaks. Addition of calcium carbonate particles (~8.8 μ]m), silica particles (~29 μm) and wood ash particles (~160 μm) in Blacksburg, VA tap water at a water pressure of 10 psi increased the fraction of remediated iron pipe leaks of 280–1000 μm diameter sizes. Although the control condition with no added particles for 58 days resulted in remediation of 0/12 leaks, remediation rate increased to 1/12 with calcium carbonate particles, to 10/12 with silica particles and to 10/12 with wood ash particles. Leak size and particle size played an important role in controlling the remediation success rate. The strength of the in-situ leak repair was sometimes very strong and resilient. The sealing materials of leak-holes repaired at 20–60 psi could sometimes withstand a 100 psi water pressure without failure, demonstrating the potential of the approach to sustain aging and leaking infrastructure. In-situ leak repair can also occur naturally, and the success rate might be unintentionally altered by adjustment of chemistry or treatments that decrease or increase particulates. / Ph. D. / Old and leaking pipes waste water resources and can contaminate water. Upgrading of drinking water systems represents a large financial burden for water utilities and home owners. The traditional approaches to repair or replace the leaking water pipes are very effective, but will take decades to implement even if a financial commitment to do so was made immediately. A new approach of leak remediation, achieved by changing the drinking water chemistry, could potentially reduce leak rates and repair water leaks while in use without digging up the buried water pipes. Therefore, leak remediation could extend the lifetime of existing infrastructure at relatively low cost and inconvenience, and may be necessary if society cannot afford pipe replacement. Recent field observations indicate that metal corrosion, one type of reaction that eats up water pipes and causes water leaks, could clog the leaks via the corrosion products. And the repair in most cases could last for a long period of time. Our work was the first to reproduce the field observations in the laboratory, revealing that water pipe leaks could be successfully clogged or remediated by natural corrosion reaction products, if the water chemistry is favorable. Additionally, our work also showed that water leaks could be clogged or remediated by addition of water particles to drinking water, which was practiced by Roman engineers a long time ago. There are legitimate health concerns about particulates because they are indicative of microbial risks, but addition of particulates to water at low levels might heal pipes without such concerns. We also proved that in some cases the repaired materials clogging the leaks could withstand a very high household water pressure, showing that the sealing materials in water leaks repaired with natural corrosion products or added water particles could create long term repairs. With improved practical understanding this approach might be usefully applied, either intentionally to repair existing leaks, or make sure that changes to water chemistry do not unintentionally make problems worse.

Recurrent events are very common in a wide range of scientific disciplines. The majority of statistical models developed to characterise recurrent events are derived from either reliability theory or survival analysis. This thesis concentrates on applications that arise from reliability, which in general involve the study about components or devices where the recurring event is failure. Specifically, interest lies in repairable components that experience a number of failures during their lifetime. The goal is to develop statistical models in order to gain a good understanding about the driving force behind the failures. A particular counting process is adopted, the non-homogenous Poisson process (NHPP), where the rate of occurrence (failure rate) depends on time. The primary application considered in the thesis is the prediction of underground water pipe bursts although the methods described have more general scope. First, a Bayesian mixed effects NHPP model is developed and applied to a network of water pipes using MCMC. The model is then extended to a mixture of NHPPs. Further, a special mixture case, the zero-inflated NHPP model is developed to cope with data involving a large number of pipes that have never failed. The zero-inflated model is applied to the same pipe network. Quite often, data involving recurrent failures over time, are aggregated where for instance the times of failures are unknown and only the total number of failures are available. Aggregated versions of the NHPP model and its zero-inflated version are developed to accommodate aggregated data and these are applied to the aggregated version of the earlier data set. Complex devices in random environments often exhibit what may be termed as state changes in their behaviour. These state changes may be caused by unobserved and possibly non-stationary processes such as severe weather changes. A hidden semi-Markov NHPP model is formulated, which is a NHPP process modulated by an unobserved semi-Markov process. An algorithm is developed to evaluate the likelihood of this model and a Metropolis-Hastings sampler is constructed for parameter estimation. Simulation studies are performed to test implementation and finally an illustrative application of the model is presented. The thesis concludes with a general discussion and a list of possible generalisations and extensions as well as possible applications other than the ones considered.

Magister Chirurgiae Dentium (MChD) / Water-pipe tobacco smoking (WTS) is a form of tobacco use with different names. There is a misconception that passing tobacco smoke through water reduces its harmful effects to increase its popularity. One million individuals smoke water-pipe daily, resulting in approximately five million deaths per annum globally. The toxic effects of WTS are related to the several components of the tobacco mixture. WTS contains 100 times more tar, four-fold more nicotine, eleven-fold more Carbon Monoxide (CO), and two to five-fold more polycyclic aromatic hydrocarbons than cigarettes.

Under årens gång har regelverk och byggnormer ändrats, och det har även gjort att utformningen av dessa har påverkats. Utförandekrav har övergått till funktionskrav, vilket har gjort att säkerhetsrisker kan uppstå eftersom olika metoder används vid installation. Ett sådant exempel är risken för legionellatillväxt. För att minimera denna risk har Boverket tagit fram byggregler, däribland att tappkallvattentemperaturen inte får överstiga 24°C under en period på åtta timmar då vattnet är stillastående. Baserat på detta har Säker Vatten AB utvecklat branschregler för VVS-företag och har därmed upptäckt problem då tappkallvattenledningen ligger i ett golv med installerad golvvärme. På denna grund bygger detta arbete som genom simuleringar i Comsol Multiphysics® v. 5.4 undersöker fyra modeller av kallvattenrör i golv med golvvärme. Resultatet för de fyra modellerna visar att kallvattnets temperatur överstiger 24°C vid installation av golvvärme vid användning av smala vattenrör och tunn isolering. Vid undersökning av användning av grövre rör med tjockare isolering blev resultatet att en kombination av 20mm i diameter vattenrör och 80mm isolering respektive 25mm i diameter vattenrör och drygt 50mm isolering klarade Boverkets temperaturkrav. Det framtagna resultatet visar på att det krävs en stor isoleringstjocklek vilket kan göra kallvattenledningen för stor i jämförelse med golvets tjocklek och därmed riskeras golvets stabilitet. Därför kan det vara bättre att använda en annan placering av kallvattenledningen när golvvärme installerats. / Building regulations and standards have changed over the years which has also had an impact on their design. Performance standards have changed to functional standards, which has led to potential safety hazards, as different methods are used by different stakeholders during installation. An example of a potential safety hazard is legionella growth. To minimize this particular hazard, the Swedish Board of Housing, Building and Planning has developed building regulations, including the regulation that the temperature of cold tap water cannot exceed 24°C for a period of eight hours while the water is stagnant. Based on this regulation, Säker Vatten AB has developed a set of trade standards for plumbing companies and has discovered that problems arise when cold-water pipes are situated in floors with underfloor heating. Based on the above, this project studies four models of cold-water pipes situated in floors with underfloor heating through simulations in Comsol Multiphysics® v. 5.4. The results from the four models show that the cold-water temperature exceeds 24°C when underfloor heating is installed and narrow water pipes and thin insulation are used. When studying the use of pipes with larger diameters and thicker insulation, the results show that the combinations of a 20mm diameter pipe with 80mm insulation, and a 25mm diameter pipe with just over 50mm insulation, satisfied the temperature regulations required by the Swedish Board of Housing, Building and Planning. The results obtained show that thick insulation is necessary, which can cause the cold-water pipe to be too large in comparison with the floor’s thickness, risking the floor’s stability. As a result, alternative placement of the cold-water pipe is to is to be preferred when underfloor heating is installed.

Over the last few years, several advancements have been made in water and wastewater pipe renewal technologies that have allowed utilities to utilize innovative renewal techniques that decrease project costs, the impact of the project on the surrounding citizens and environment, and allow for expedited pipeline renewals compared to traditional open trench methods. The challenge now is in getting utilities to implement new innovative technologies within their system. This thesis provides background information on a number of the technologies available for the renewal of water and wastewater system pipelines. It then provides State of the Art Literature and State of the Art Practice Reviews based on technology use trends in literature and technology use trends in utility practice. The information from both reviews is then synthesized to provide a clear view of the state of the water and wastewater pipeline renewal technology industry, including the trends by pipe material, drivers for renewal, and technology type. / Master of Science

Dans les pays développés, l’eau potable est distribuée au domicile des usagers. Ce confort requier tun long linéaire de réseau de forte valeur patrimoniale. Pour maintenir un équilibre entre ressources financières et performances, il est important d’essayer de renouveler les tronçons au meilleur moment possible. Ce manuscrit présente les modèles court (1 à 3 ans), moyen et long terme ( > 30 ans)actuellement employés. Les processus court terme semblent assez efficaces, mais les méthodes moyen et long terme restent frustes. Le modèle OPTIMEAU propose une approche long terme pour obtenir une vision globale du patrimoine de canalisations et rationaliser sa gestion, tout en restant en phase avec les pratiques opérationnelles de programmation à court terme. Cette démarche, fondée sur des modèles statistiques de survie, est testée à partir des données réelles de 3 services d’eau Européens : le SEDIF (Syndicat des Eaux d’Ile de France), le Grand Lyon et eau service Lausanne en Suisse. L’originalité de ce modèle réside dans l’estimation de la distribution des âges à la mise hors service passée, clef de voûte dans la construction de onze indicateurs liés aux finances, aux réalisations et à la performance future des services. / In developed countries, drinking water is distributed to households. This comfort requires a long networkwith a high value. To optimize resources and performance, it is important to renew pipe sectionsat the best possible time. This thesis presents the short (1-3 years), medium and long term (> 30 years)models commonly employed. The short-term processes seem quite effective, but long term methods remainrough. The OPTIMEAU model proposes a long-term approach to get a prospective overview ofpipes and improve its management, while remaining connected to the technical practices at short-termlevel. This approach, based on survival statistical models, is tested using actual data of three Europeanwater services : SEDIF (Syndicat des Eaux d’Ile de France), Grand Lyon and eauservice Lausanne inSwitzerland. The originality of this model lies in the estimation of the past decommissioning age distribution,keystone in the construction of eleven indicators related to finance, achievements and futureperformance of water utilities.

För att minska framtida problem med läckor på våra ledningsnät är det viktigt att man förnyar dessa. Planeringen av denna förnyelse kallas för förnyelseplanering. En metod i förnyelseplaneringen är så kallad ”riskbaserad förnyelseplanering”. Denna metod syftar till att hitta de ledningar som innebär störst risk. Med hög risk menas: en ledning som har hög sannolikhet för brott, samtidigt som konsekvensen av att ett brott uppstår är stor. Tekniska Verken i Linköping ansvarar för vattenledningsnätet i Linköpings kommun. I sin förnyelseplanering arbetar man på att få fram ett nytt verktyg, kallat ”Knappen”. Ambitionen med ”Knappen” är kunna hitta sina riskledningar med ”endast ett knapptryck”. ”Knappen” är en beräkning som baseras på en mängd indata om sannolikhet och konsekvens. En av faktorerna som ska användas i beräkningen är en uppskattning av reparationskostnaden läckan medför. Denna undersökning har resulterat i en formel för beräkning av denna kostnad. Formeln är baserad på data om tidigare läckor från 2011. De faktorer som formeln visade sig bero på är: vilken marktyp läckan har skett i, hur långt avståndet är, vilken reparationsmetod man måste använda samt ledningens material och diameter. För en läcka i en segjärnsledning med dimensionen 150 mm som måste lagas med en infällning blir reparationskostnaden enligt formeln 118 740 kr om den inträffade i en villagata. Om samma förutsättningar gäller för en läcka i en gjutjärnsledning med dimensionen 100 mm som tätas med en repmuff blir reparationskostnaden enligt formeln 62 060 kr. / Water is an essential resource that we today take for granted. The distribution of drinking water is done with pipes in our water distribution network. These pipes have a limited lifetime and at some point they will rupture, with a leak as a result. The leak can lead to major consequences. Some examples are: disturbance in traffics, damage to property, as well as private individuals and businesses that are without water. Another consequence is the cost itself of repairing the leak, which sometimes is the most severe consequence. To avoid future problems with water leaks, it is important to renew the pipe network. The planning of this renewal is called renewal planning. A method in renewal planning is so-called “risk-based renewal planning”. This method aims to find the pipes that carry the highest risk. A pipe with high risk is a pipe that has high probability of rupturing, at the same time as the consequence of a rupture is great. Tekniska Verken in Linköping is in charge of the water distribution network in Linköping municipality. In their renewal planning they are working on a new tool, called “Knappen”. The ambition with “Knappen” is to be able to find pipes with high risk with “just one touch of a button”. “Knappen” is a calculation based on a variety of input data on probability and consequence. One of the factors to be used in the calculation is an estimate of the repair cost that the leak causes. This study has resulted in a formula for calculating this cost. The formula is based on data about past leaks from 2011. The factors that the formula turned out to depend on is: in which land type the leak has occurred, how far the distance is, which repair method has to be used and also the material and dimension of the pipe.

Lärande med elektroniska medel har potentialen att revolutionera lärande. Via datorskärmen kan man enkelt åskådliggöra fysikaliska fenomen och underlätta arbetet för läraren. Om en utbildning bedrivs elektroniskt med hjälp av en dator och på distans uppstår en del svårigheter men samtidigt möjligheter, jämfört med en traditionell utbildning med fysisk närvaro i en skola. Datorer ger möjligheten att ta hänsyn till pedagogiska aspekter som kan effektivisera lärande. I dagens läge finns det inte ett utarbetat sätt att lära ut med elektroniska medel som garanterar ett gott lärande resultat. Hur en elektronisk kurs utformas är upp till läraren och institutionen som erbjuder kursen. I denna rapport ger vi ett enkelt förslag på hur vi anser en elektronisk kurs bör vara utformad samt det innehållet i kursen bör täcka. / Teaching by electronic means has the potential to revolutionize teaching. The screen of the computer can easily visualize physical phenomenon and facilitate the work of the teacher. If an education is conducted electronically and by distance it creates some difficulties but at the same time opportunities, compared to traditional education with a physical presence at a school. Today there is no prepared way to teach by electronic means that guarantees good teaching results. How an electronic course is formed is decided by the teacher and the institution offering the course. In this report we give a simple suggestion of how we consider an electronic technics course should be formed and what the course content should cover.