Starting with tensor calculus and the variational form of the Hamiltonian functional, a generalized theory is formulated for doubly curved thin shells. The formulation avoids geometric approximations commonly adopted in other formulations. The theory is then specialized for cylindrical and toroidal shells as special cases, both of interest in the modeling of straight and elbow segments of pipeline systems. Since the treatment avoids geometric approximations, the cylindrical shell theory is believed to be more accurate than others reported in the literature. By adopting a set of consistent geometric approximations, the present theory is shown to revert to the well known Flugge shell theory. Another set of consistent geometric approximations is shown to lead to the Donnell-Mushtari-Vlasov (DMV) theory. A general closed form solution of the theory is developed for cylinders under general harmonic loads. The solution is then used to formulate a family of exact shape functions which are subsequently used to formulate a super-convergent finite element. The formulation efficiently and accurately captures ovalization, warping, radial expansion, and other shell behavioural modes under general static or harmonic forces either in-phase or out-of-phase. Comparisons with shell solutions available in Abaqus demonstrate the validity of the formulation and the accuracy of its predictions. The generalized thin shell theory is then specialized for toroidal shells. Consistent sets of approximations lead to three simplified theories for toroidal shells. The first set of approximations has lead to a theory comparable to that of Sanders while the second set of approximation has lead to a theory nearly identical to the DMV theory for toroidal shells. A closed form solution is then obtained for the governing equation. Exact shape functions are then developed and subsequently used to formulate a finite element. Comparisons with Abaqus solutions show the validity of the formulation for short elbow segments under a variety of loading conditions. Because of their efficiency, the finite elements developed are particularly suited for the analysis of long pipeline systems.

Den här examensarbete är en utredning av värmeförluster och ekonmiska besparingar av olika fjärrvärmerör. En fiktiv fjärrvärmeförläggning på 100m, för respektive dimension av fjärrvärmerör, har legat till grund för beräkningarna. Syftet är att få en klar bild på hur lönsamt det är att använda sig utav isoleringsserie 3 istället för isoleringsserie 2 alternativt dubbelrör med isoleringsserie 2 när förutsättningar tillåter detta.Resultaten visar att dubbelrör i mindre dimensioner har en lägreinvesteringskostnad, har lägre värmeförluster och ger en större vinst än vad enkelrör serie 2 och serie 3. För dubbelrör i större dimensioner så är investeringskostnaderna något högre men värmeförlusterna mycket lägre.I jämförelsen mellan serie 2 och serie 3 så är serie 3 lönsamt i båda fallen.Dessa resultat visar att det gynnar fjärrvärmenätägare i längden att använda sig utav en högre isoleringsserie alternativt dubbelrör.Examensarbetet har ej utrett miljöpåverkan av respektive rör, ej heller har kontirör undersökts. / This thesis is an evaluation of heat losses and economical savings for different types of district heating pipes. Calculations have been based on a fictional district heating system with the length 100m, for each district heating pipe dimension. The cause is to get a clear image of how profitable it is to use a higher series of insulation alternatively using twin pipes when it’s possible.The results show that twin pipes in lower dimensions has a lower investment cost, less heat losses and is more profitable than insulation series 2 and series 3. When it comes to twin pipes with a higher dimension the investment cost is slightly higher than single pipe insulation series 3, though the heat losses are much lower.The comparison between series 2 and series 3 show that series 3 is more profitable in both cases.These results show that it’s profitable for the network owners in the long-term to use either a higher insulation series or twin pipes.No evaluation of neither the impact on the environment or district heating pipes with diffusion barrier, has been done.

The problem of the formation of the beaded pipe ends by reduction described in this work. Patent and literature review ways to reduce the longitudinal varying wall thickness is made. Technology for the production of pipes for pipe-rolling plant is shown. An improved method for calculating changes in wall thickness of the pipe in the reducing mill developed. Mode calculation thinning ends of the pipe before the reducing mill is made. / В данной работе описана проблема образования утолщенных концов труб при редуцировании. Выполнен патентно-литературный обзор способов снижения продольной разностенности при редуцировании труб. Приведена технология производства труб на ТПА-80. Разработана усовершенствованная методика расчета изменения толщины стенки трубы в редукционном стане. Выполнен расчет режима утонения концов труб перед редукционным станом.

The history of land utilization in Scandinavia is characterized by two major periods of open landscape. The first one temporal ranged from cal. AD 0-500 and the second one ranged from cal. AD 1200-1900 including the medieval crisis in Scandinavia. Both periods were characterized by animal husbandry and intensive grazing as well as cultivation. However, slash-and-burn-cultivation and hay production on mires and meadows were prevailing during the medieval crisis. These activities significantly altered the concentration of transported organic carbon (OC) from the terrestrial ecosystem to inland waters. Burning and grazing decreased the terrestrial OC and water table, due to reduction of biomass, whereby burning has a greater effect. Biennial scything of mires for hay production reduced the biomass as well, hence resulting in a decreasing water table and peat accumulation. Even though two periods of open landscape has been present in the historical land utilization of Scandinavia, only the latest one resulted in a decreasing OC concentration in surface water in boreal lake. This indicates that especially the slash-and-burn cultivation and hay production on mires are very important components of altering the carbon storage in soils and peat due to lowering the terrestrial OC pool.

Master of Science / Department of Architectural Engineering and Construction Science / Thomas Logan / Typical building sanitary lines are sloped at a minimum of 1/8” to utilize gravity and prevent liquid separation from solid waste. The purpose of this research is to analyze how a lesser amount of water from a 1.6 gallon per flush water closet affects drainage in a four inch diameter pipe at 1/4" slope. Low flow water closet manufacturers ensure that waste clears the bowl, but there is no significant research following the flushed water further down the pipe line. This research utilizes a 1.6 gallon per flush floor-mounted water closet connected to 30 feet of sloped four inch PVC Drain Waste Vent piping. Data presented from 25 flush trials indicates that further research needs to be conducted at a smaller pipe diameter. Four-inch piping is too large, causing the 1.6 gallons of water to quickly lose the required force over the course of 30 feet, resulting in pipe line clogs. An average of four additional water-only flushes are necessary to completely clear the test media and toilet paper from the pipe. This research references previously published research and focuses on test results presented by the Plumbing Efficiency Research Coalition. Two case studies of city wide replacements of old water closets are presented to discuss the viability of city wide mandates in relation to water conservation.

Submitted in fulfillment of the requirements of the Degree of Magister Technologiae: Civil Engineering, Durban University of Technology, 2013. / The urgent need to rehabilitate or replace ageing deteriorated buried potable water pipeline networks is one of the many critical service utility provision challenges faced within the municipalities in South Africa. The majority of these unreliable deteriorated pipeline networks consist of un-dipped (not coated with bitumen) AC piping which have long passed their planned economic and technical lifespan. Traditionally, the open trenching method has been utilised for the replacement of aged and deteriorated piping. However, this traditional open trenching method has shown to be expensive and difficult to implement, particularly in congested high traffic use urban areas. The need to rehabilitate or replace the ageing deteriorated buried potable water pipelines in South Africa, taking into account the above mentioned expensive factors has a solution. This solution is termed ‘trenchless technology’ and sometimes also termed ‘no dig’. Recent advancements in trenchless technologies now include innovative methods such as pipe bursting, close-fit lining and sliplining. Close-fit compact pipe manufactured by Wavin Overseas B.V. was newly introduced in South Africa in 2010 for the rehabilitation of deteriorated pipelines. These trenchless methods require further research into their technical application merits, drawbacks and costs in relation to the traditional open trenching method in order to determine which method is more expensive and also least suitable. Traditionally, the ‘total cost’ associated with pipe rehabilitation or replacement projects consisted only of the direct costs. The indirect and socio-economic inconvenience costs were often ignored and resulted in costly expenses to the municipalities. However, this research will show that these indirect and socio-economic inconvenience costs must form part of the total cost of a project as it assists with the successful completion of the project without expensive unforeseen costs to the municipalities. In addition, this research will provide insight as to which indirect and socio-economic inconveniences are dominantly experienced by the public. To achieve this, a quantitative socio-economic survey questionnaire was developed. This questionnaire was aimed at residents and business owners who were affected during a project of this nature. This research study will serve as a support tool to municipalities of South Africa when selecting a pipe rehabilitation or replacement method. This support tool will provide key technical merits and drawbacks of the traditional open trenching method, pipe bursting method, close-fit compact pipe method and sliplining method. In addition, this research study will compare the ‘total cost’ of the traditional open trenching method against the trenchless pipe bursting method. The decision making process lies in the hands of the municipal technical managers. Therefore, their knowledge and experience of up to date information on trenchless methods (as well as the traditional open trenching method) is vitally important. This research provides insight as to the knowledge and experience of technical municipal staff on trenchless methods, its application and use in South Africa. A quantitative survey questionnaire was developed by the researcher. This questionnaire was aimed at technical staff in the water departments of district and local municipalities of South Africa. The results of the above questionnaire surveys formed part of the eThekwini Water and Sanitation (EWS) Feasibility study funded by the Dutch Government. When comparing the costs of the trenchless pipe bursting method against the traditional open trenching method, the results revealed that trenchless methods are undoubtedly cheaper and far less disruptive to the public. The results of the socio-economic survey revealed that trenchless methods were preferred by the public since it was less disturbing and the hindrances experienced were also far less than the traditional open trenching method. The results of the technical municipal survey questionnaire revealed that at least 50% of municipal technical staff of South Africa are not adequately informed about trenchless methods, its application and technical merits and drawbacks respectively. This survey questionnaire revealed that South Africa may be advancing over the years on the use of trenchless methods, however, more educating in the form of training, seminars and other methods of marketing must be undertaken starting at a municipal level.

This project investigated the effect of PP skin on the PE core pipe in a PP/PE dual layer pipe during production and outdoor exposure under various radiation dosages by comparing the results with the corresponding uncoated pipe using different characterization techniques. It was found for unaged samples that after extrusion the adhesion reducer present in the PP skin migrated to the PE core pipe outer surface but had little effect on the electrofusion (EF) joint quality. The PP skin prevents the PE core pipe from quenching therefore more perfect PE crystal is formed as shown by a higher crystallinity and the residual stress is reduced as shown by a slit ring method. Due to the reduced residual stress, the skinned pipe had higher long term hydrostatic strength (LTHS) than the uncoated pipe. After outdoor weathering, photo-oxidation products were evident at the solar irradiated PP outer surface after 3 GJ/m2 weathering and the whole PP outer surface was oxidized after 10 GJ/m2 weathering. By deconvoluting the IR peaks, ketones, carboxylic acid and esters were found the main products. Although only slight photo-oxidation was identified after 10 GJ/m2 aging on the uncoated PE pipe outer surface, oxidation induction time (OIT) results indicated that the solar irradiated side of the surface lost most of its antioxidants after only 1 GJ/m2 weathering which led to production of weak layer in the EF joint. In the middle pipe wall and at the inner surface, a more gradual decrease of antioxidant was found. The skinned pipe showed better resistance to antioxidant loss than the uncoated pipe and still had adequate antioxidant for EF. The thermal effect of solar irradiation was thought to cause secondary crystallization of the uncoated pipe at the irradiated side and release of residual stress of both uncoated and skinned pipes after aging. The residual stress release rate was found to decline with weathering. As the pipe with thicker skin always had a lower residual stress, it can be inferred that the skinned pipe still had a higher LTHS value than the uncoated pipe even after aging.

The following paper presents a one-dimensional numerical model for simulating transient thermohydraulic pipe flow based on the Method of Characteristics. In addition to mass and momentum conservation, the proposed scheme also guarantees compliance with the laws of thermodynamics by solving the energy equation. The model covers transient changes in fluid properties due to pressure changes, heat transfer and dissipation. The presented methodology also allows the computation of the transient temperature distribution in the pipe wall through an additional ordinary finite difference scheme. The numerical procedure is implemented in the commercial simulation software DSHplus. The capability of the code is examined by comparing the simulation results with theoretical solutions and experimental data.

Thesis (MSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: A tunable narrow-bandwidth vacuum ultra violet laser source was developed and characterised. Two-photon resonant four-wave sum-frequency mixing of two pulsed dye laser beams in magnesium vapour was used to generate the VUV laser light. A heat pipe oven with a concentric design was incorporated to provide a magnesium vapour column of around 30 cm in length with a sufficiently stable temperature and appropriate vapour pressure for efficient VUV production. This is a longer nonlinear medium length than previously produced in our laboratory using a crossed heat pipe oven. The longer medium facilitated the production of VUV laser light of higher intensity than was previously obtainable. High resolution laser induced fluorescence spectra of carbon monoxide in a supersonic gas jet was recorded using the tunable VUV laser light produced in the crossed heat pipe oven. Experimental parameters were optimised and adjusted for the selective detection of the forbidden singlet-triplet transitions which typically have longer lifetimes than singlet-singlet transitions. Transitions from the X¹Σ⁺(v = 0) ground state to the e³Σ⁻( v = 5) triplet state were recorded, and accurate wavelength for the spectral lines were determined. Laboratory wavelengths for these lines have not been measured previously. Accurate wavelength for the weak forbidden spectral lines of CO are important in astrophysical applications, for example determining column densities of interstellar gas clouds. / AFRIKAANSE OPSOMMING: 'n Afstembare smal bandwydte vakuum ultraviolet laser bron is ontwikkel en gekarakteriseer. Twee-foton resonante vier-golf som-frekwensie vermenging van twee gepulseerde kleurstoflaserbundels in 'n magnesium damp is gebruik om die VUV laser lig te produseer. 'n Hittepyp oond met 'n konsentriese ontwerp is in gebruik geneem om a magnesium damp kollom van ongeveer 30 cm in lengte te voorsien waarvan die temperatuur voldoende stabiel is en die dampdruk toepaslik is vir effektiewe VUV produksie. Dit is 'n langer nie-liniêre medium as wat in die verlede deur 'n kruis-hittepyp oond voorsien is. Die langer medium het dit moontlik gemaak om VUV laser lig van hoër intensiteit te produseer as wat tot dusver bereikbaar was. Hoë resolusie laser geinduseerde fluoresensie spektra van koolstof monoksied in a supersoniese gasstraal is opgeneem met die hulp van die afstembare VUV laser lig geproduseer in die kruis-hittepyp oond. Eksperimentele parameters is geoptimeer en verstel vir die selektiewe waarneming van die verbode singlet-triplet oorgange wat tipies langer leeftye besit in vergelyking met singlet-singlet oorgange. Oorgange vanaf die X¹Σ⁺(v = 0) grond toestand na die e³Σ⁻( v = 5) triplet toestand is opgeneem en akkurate golflengtes vir die spektrale lyne is bepaal. Laboratorium golflengtes het tot dusver nie bestaan vir hierdie lyne nie. Akkurate golflengtes vir die swak verbode spektrale lyne van CO het belangrike toepassings in astrofisika soos die bepaling van die kollom digtheid van interstellêre gas wolke.

Thesis (MBA)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: The continuous growth in the world’s population together with the increasing scarcity of water resources, especially drinkable water, has cultivated an environmentally-conscious society. As consumers are looking for eco-friendly alternatives or methods, manufacturers are including environmentally-friendly (EF) products in their product mix to address this topic. However, there seems to be a disconnect between manufacturers of EF product solutions and consumers. Consumers are either not aware of EF products or they are still hesitant in adopting environmentally-friendly products as the perception is that they are either too expensive or there is something amiss with the product’s functionality. It is up to suppliers and marketers of EF goods to do a better job of educating consumers about their products. This research study was conducted to understand the domestic consumer’s ecological behaviour and key influencing factors when purchasing water-efficient fittings. The literature review in this study gives us background on the status quo in terms of climate change, the green consumer, and water supply issues. A survey was conducted amongst domestic consumers in the plumbing retail environment to test their willingness to purchase water-efficient fittings based on their profile, habits and key influencing factors. The profile of the respondent showed a consumer who is more affluent. The water-efficient consumer’s primary concern is to save costs by reducing their water bill. Cost saving is the key influencing driver in terms of consumer’s willingness to purchase water-efficient fittings.