Yes / The performance of Ground Source Heat Pump (GSHP) systems for domestic use is an increasing area of study in the UK. This paper examines the thermal performance of three bespoke shallow horizontal GSHP systems installed in newly built residential houses in the North of England against a control house which was fitted with a standard gas boiler. A total of 350 metres of High Density Polyethylene pipe with an external diameter of 40 mm was used for each house as a heat pump loop. The study investigated (i) the performance of a single loop horizontal Ground Heat Exchanger (GHE) against a double loop GHE and (ii) rainfall effects on heat extraction by comparing a system with an infiltration trench connected to roof drainage against a system without an infiltration trench above the ground loops. Parameters monitored for a full year from October 2013 to September 2014. Using the double GHE has shown an enhanced performance of up to 20% compared with single GHE. The infiltration trench is found to improve performance of the heat pumps; the double loop GHE system with an infiltration trench had a COP 5% higher than that of the double loop GHE system without a trench.

Deep soil mixing to construct stiff columns is one of the methods used today to improve performance of loose ground and remediate liquefaction problems. This research adopts a numerical approach to study seismic performance of soil-cement columnar reinforcements in loose sandy profiles. Different constitutive models were investigated in order to find a model that can properly predict soil behavior during seismic excitations. These models included NorSand, Dafalias-Manzari, Plasticity Model for Sands (PM4Sand) and Pressure-Dependent-Multi-Yield-02 (PDMY02) model. They were employed to predict behavior of soils with different relative densities and under different confining pressures during monotonic and cyclic loading. PDMY02 was identified as the most suitable model to represent soil seismic behavior for the system studied herein. The numerical aspects of the finite element approach were investigated to minimize the unintended numerical miscalculations. The focus was put on convergence tolerance, solver time-step, constraint definition, and, integration, material and Rayleigh damping. This resulted in forming a robust numerical configuration for 3-D nonlinear models that were later used for studying behavior of the reinforced grounds. Nonlinear finite element models were developed to capture the seismic response of columnar reinforced ground during dynamic centrifuge testing. The models were calibrated with results from tests with unreinforced profiles. Thereafter, they were implemented to predict the response of two reinforced profiles during seismic excitations with different intensities and liquefaction triggering. Model predictions were compared with recordings and the possible effects from the reinforcements were discussed. Finally, parametric studies were performed to further evaluate the efficiency of the reinforcements with different extension depths and area replacement ratios. The results collectively showed that the stiff elements, if constructed appropriately, can withstand seismic excitations with different intensities, and provide a firm base for overlying structures. However, the presence of the stiff elements within the loose ground resulted in stronger seismic intensities on the soil surface. The columns were not able to considerably reduce pore water pressure generation, nor prevent liquefaction triggering. The reinforced profiles, comparing to the free-field profiles, had larger settlements on the soil surface but smaller settlements on the columns. The results concluded that utilization of the columnar reinforcements requires great attention as these reinforcements may result in larger seismic intensities at the ground surface, while not considerably reducing the ground deformations. / Ph. D.

Thesis (Ph. D. in Civil Engineering)--University of California, Berkeley, 2006. / Cover title. "Fall 2006." Includes bibliographical references (leaves 292-300). Also available online.

L'industrie nucléaire est une industrie génératrice de déchets, dont certains sont radioactifs. Ces déchets radioactifs ont des formes et des origines diverses, allant de la paire de gant de manutention faiblement contaminés, à la suspension aqueuse de produits de fissions hautement radioactifs. Dans ce travail, un type de déchet bien particulier a été étudié ; des boues issues de la décontamination d'effluents liquides radioactifs, possédant entre autres les trois particularités suivantes ; * Etre moyennement radioactif, selon les critères de l'ANDRA. * Etre composé d'une forte teneur en eau de constitution (ne pouvant être retirée par simple évaporation) ; * Etre composé d'un sorbant (PPFeNi) dont la stabilité chimique n'est pas assurée pour un pH supérieur à 11. Ces particularités font qu'un enrobage dans une matrice minérale forte consommatrice d'eau, et bas-pH (pH < 11) est envisageable. Le choix c'est alors porté sur le développement d'une matrice ettringitique réalisée à partir d'un mélange de Ciment d'Aluminate de Calcium (CAC) et de sulfate de calcium. Dans un premier temps, la stabilité du sorbant du césium utilisé dans cette étude a été testée dans différents environnements de pH (2 à 14) et de température. Pour cela des analyses chimiques de solution ainsi que des caractérisations du composé par diffraction de rayons X, FTIR et microscopie électronique à balayage-EDS ont permis de fixer les bornes de stabilité que la formulation ettringitique doit avoir. Puis une étude microstructurale (nature et morphologie des produits) de mélanges ettringitiques binaires CAC/sulfate de calcium type hémihydrate et/ou anhydrite a été effectuée afin de caractériser la stabilité de l'ettringite, hydrate fort consommateur d'eau. Les propriétés bas-pH ont été vérifiées notamment par analyse chimique de solutions porales. Certaines limites de ces systèmes concernant le dégagement de chaleur et la possible formation de systèmes expansifs ont été mises en évidence. L'effet de l'augmentation du rapport eau/liant, responsable d'un effet de dilution et permettant de réduire les deux effets précédents, a été également regardé pour ces systèmes binaires. Afin de réduire la chaleur dégagée à court terme tout en permettant le développement de l'hydratation à long terme de systèmes ettringitiques, ces systèmes binaires ont été substitués par des additions minérales à hydraulicité latente type laitier de haut fourneau. Une étude microstructurale de la réactivité du laitier et de la modification de l'assemblage ettringitique a montré une réactivité modérée de ce dernier à jeune âge conformément aux attentes. Pour favoriser sa réactivité à long terme par activation alcaline/sulfatique différentes proportions de sulfate de calcium à dissolution plus lente ont été testés. Les caractéristiques microstructurales de ces systèmes ternaires en présence de différentes teneurs en eau intrinsèquement liée à la nature de type boue du déchet a été étudiée. Enfin, les différentes informations sur l'effet des paramètres de formulation obtenues ont débouché sur la mise en place de tests sur des formulations contenant un déchet simulé inerte et enrichi en chlorures. Des essais systématiques de fluidité, de résistances mécaniques et pour certains d'entre eux d'expansion et de dégagement de chaleur doivent permettre d'identifier une série de mélanges adaptés au test à l'échelle de prototype industriel pour la cimentation de boues. / Nuclear industry generated waste including radioactive wastes, which have different forms and origins. The wastes produced by reprocessing of nuclear fuel are characterized by important water content, by high pH and temperature sensitivity. The cementation in ettringite systems might be a promising solution to solidify radioactive wastes. Mixtures of Calcium Aluminate Cement (CAC) and calcium sulfate are planned to be used, instead of Ordinary Portland Cement (OPC), to form a significant amount of ettringite able to catch water molecules when forming. Moreover, due to the low pH of CAC-based matrices, the latter have a good compatibility with the compounds used to stabilize active elements. Initially, the stability of the sorbent of cesium used in this study was tested in different pH environments (2 to 14) and temperature. Chemical analysis and different microstructural characterizations like X-ray diffraction, FTIR and SEM-EDS have allowed to set stability limits of ettringite systems. Then microstructural study on binary systems composed by mixture of CAC/calcium sulfate (hemihydrate and/or anhydrite) was realized to characterize ettringite stability during the time of hydration. Low pH properties were checked by chemical pore solutions analysis. However, the heat generated by hydration and the possible formation of expansive systems require an increase of e/s ratio and additional components like Ground Granulated Furnace Slag (GGBS). These two parameters were studied subsequently. Microstructural study of GGBS reactivity and the modification of ettringite assemblage were showed that GGBS act as filler at early time of hydration. To promote the GGBS reactivity at long term of hydration by alkaline and sulfate activation, different nature of calcium sulfate was used. Then the microstructural characteristic of this ternary system in presence of different e/s ratio was studied. Finally, different information on the effect of formulation parameters obtained led to the development of tests on formulations containing an inert simulated waste and enriched in chlorides. Systematic tests of fluidity, mechanical strength and for some expansion and heat generation should identify a series of mixtures adapted to test prototype to industrial scale for cementing wastes.

Studien använder linjärprogrammering för att optimera driften av det termiska energisystemet på Karlstad centralsjukhus ur ett ekonomiskt perspektiv. Bakgrunden till studien är de höga elpriser som rådde under slutet av 2021 samt att det i dagsläget finns kunskapsluckor angående hur systemet bör köras optimalt. Studien baseras på driftdata från 2021. Energisystemet som optimeras är uppbyggt av kylvärmepumpar, bergvärmepumpar, kylmaskiner, frikyla, fjärrvärme och marklager. Ett förhållande för hur många kWh termisk energi som produceras per tillförd kWh el tas fram för samtliga komponenter, vilket sedan används för att modellera energisystemet. Optimering av systemet ger vilka komponenter som skall användas vid olika tidpunkter för att uppfylla ett bestämt värmebehov och kylbehov. Resultatet i form av optimal drift under 2021 analyseras och används för att ta fram driftrekommendationer för energisystemet i framtiden. En metod för att teoretiskt begränsa marklagrets kapacitet vid optimering presenteras. Metodenanvänder nettoenergi till marklagret över en specifik tidsperiod för att approximera temperaturen på brinevätskan ut ur marklagret. Genom att sätta temperaturbegränsningar på brinevätskan kan därigenom nettoenergin till marklagret begränsas. Baserat på data från 2021 tillåts nettoenergin till marklagretvariera mellan -14 700 kWh och 12 500 kWh per 24 timmar. Resultaten visar att det under vintern är fördelaktigt att primärt använda bergvärmepumparna A-D i kombination med frikyla. Sekundärt används kylvärmepumparna E-F. Skillnaden mellan primär och sekundär systemlösning är liten och de båda kan ses som relativt likvärdiga. Fjärrvärme används enbart som sista alternativ under vintern. Energikällan för bergvärmepumparna bör variera mellan Klarälven och marklager med avsikt att utnyttja marklagrets kapacitet optimalt. Vår och höst fallet är till stora delar likvärdigt med vinterfallet med undantaget att det innehåller fler variationer till följd av förändringar i omgivande förutsättningar. Under sommaren bör enbart fjärrvärme användas för att tillgodose värmebehovet. Frikyla och kylmaskinerna 2-3 används för att tillgodose kylbehovet. Frikyla reserveras till att användas under de tidpunkter då kylbehovet är som högst. Effektavgiften för fjärrvärme står för 25,7 % av total driftkostnad i optimalt driftfall. För att minska kostnaderna anses det därför viktigt att kapa effekttopparna för fjärrvärme. Studien undersöker eventuella fördelar med att koppla frikyle-värmeväxlaren mot Klarälven med avsikt att kunna utnyttja den mer än vad som görs i dagsläget. Systemlösningen ger ingen signifikant minskning av driftkostnader vid simulering av ett års drift. Det kan dock vara fördelaktigt att koppla frikyla mot Klarälven ur perspektivet att kunna justera nettoenergin till marklagret för att förhindra långsiktiga temperaturförändringar i berggrunden. Årlig driftkostnad kan minskas genom att öka maxkapaciteten för värmepumparna. En ökning avbergvärmepumparnas kapacitet motsvarande en komponent minskar total årlig kostnad med 4,6 %. En ökning av kylvärmepumparnas kapacitet motsvarande en komponent minskar total årlig kostnad med 1,5 %. Att öka maxkapaciteten för övriga komponenter ger ingen signifikant förändring av årlig driftkostnad. Förbättring av studien innebär att basera modellen på bättre indata samt ta hänsyn till fler detaljer i systemet. Vidare studier bör fokusera på att tillämpa resultaten för att verifiera dem i verkligheten samt göra investeringskalkyler över att utöka kapaciteten för värmepumparna. / The study uses linear programming to optimize the operation of the thermal energy system at Karlstad Central Hospital from an economic perspective. The background to the study is the high electricity prices that occurred at the end of 2021 and the fact that there are currently knowledge gaps regarding how the system should be run optimally. The study is based on operational data from 2021. The energy system that is optimized is made up of cooling heat pumps, ground source heat pumps, cooling machines, free cooling, district heating and ground storage. A ratio for how many kWh of thermal energy that is produced per kWh of supplied electricity was produced for all components, which was then used to model the energy system. Optimization of the system provides which components are to be used at different times to meet a specific heating and cooling demand. The result in the form of optimal operation during 2021 is analyzed and used to produce operating recommendations for the energy system in the future. A method for theoretically limiting the capacity of the ground storage during optimization is presented. The method uses net energy to the ground storage over a specific period of time to approximate the temperature of the brine liquid out of the ground storage. By setting temperature limits on the brine liquid, the net energy to the ground storage can thereby be limited. Based on data from 2021, the net energy to the ground storage is allowed to vary between -14 700 kWh and 12 500 kWh per 24 hours. The results show that during the winter it is advantageous to primarily use the ground source heat pumps A-D in combination with free cooling. Secondary, the cooling heat pumps E-F are used. The difference between primary and secondary system solution is small and the two can be seen as relatively equivalent. District heating is only used as a last resort during the winter. The energy source for the ground source heat pumps should vary between the Klarälven river and the ground storage with the intention of utilizing the capacity of the ground storage optimally. The spring and autumn case is largely equivalent to the winter case, with the exception that it contains more variations as a result of changes in surrounding conditions. During the summer, only district heating should be used to meet the heat demand. Free cooling and cooling machines 2-3 are used to meet the cooling needs. Free cooling is reserved for use during the times when the cooling demand is at its highest.The power fee for district heating accounts for 25.7% of the total operating cost in the optimal operating case. To reduce costs, it is therefore considered important to cut the power peaks for district heating. The study examines the possible benefits of connecting the free cooling heat exchanger to the Klarälven river with the intention of being able to use it more than what is currently the case. The system solution does not provide a significant reduction in operating costs when simulating one year of operation. It might however be advantageous to connect free cooling to the Klarälven river from the perspective of being able to adjust the net energy to the ground storage to prevent long-term temperature changes in the bedrock. Annual operating costs can be reduced by increasing the maximum capacity of the heat pumps. An increase in the capacity of the ground source heat pumps equivalent to one component reduces the total annual cost by 4.6%. An increase in the capacity of the cooling heat pumps equivalent to one component reduces the total annual cost by 1.5%. Increasing the maximum capacity for the other components does not result in a significant change in annual operating costs. Improvements of the study means basing the model on better input data and taking into account more details in the system. Further studies should focus on applying the results to verify them in reality andmake investment calculations regarding expansion of the capacity of the heat pumps

One of the most difficult tasks towards designing earthquake resistant structures is the determination of critical earthquakes. Conceptually, these are the ground motions that would induce the critical response in the structures being designed. The quantification of this concept, however, is not easy. Unlike the linear response of a structure, which can often be obtained by using a single spectrally modified ground acceleration history, the nonlinear response is strongly dependent on the phasing of ground motion and the detailed shape of its spectrum. This necessitates the use of a suite (bin) of ground acceleration histories having phasing and spectral shapes appropriate for the characteristics of the earthquake source, wave propagation path, and site conditions that control the design spectrum. Further, these suites of records may have to be scaled to match the design spectrum over a period range of interest, rotated into strike-normal and strike-parallel directions for near-fault effects, and modified for local site conditions before they can be input into time-domain nonlinear analysis of structures. The generation of these acceleration histories is cumbersome and daunting. This is especially so due to the sheer magnitude of the data processing involved. The purpose of this thesis is the development and documentation of PC-based computational tools (hereinafter called EQTools) to provide a rapid and consistent means towards systematic assembly of representative strong ground motions and their characterization, evaluation, and modification within a performance-based seismic design framework. The application is graphics-intensive and every effort has been made to make it as user-friendly as possible. The application seeks to provide processed data which will help the user address the problem of determination of the critical earthquakes. The various computational tools developed in EQTools facilitate the identification of severity and damage potential of more than 700 components of recorded earthquake ground motions. The application also includes computational tools to estimate the ground motion parameters for different geographical and tectonic environments, and perform one-dimensional linear/nonlinear site response analysis as a means to predict ground surface motions at sites where soft soils overlay the bedrock. While EQTools may be used for professional practice or academic research, the fundamental purpose behind the development of the software is to make available a classroom/laboratory tool that provides a visual basis for learning the principles behind the selection of ground motion histories and their scaling/modification for input into time domain nonlinear (or linear) analysis of structures. EQTools, in association with NONLIN, a Microsoft Windows based application for the dynamic analysis of single- and multi-degree-of-freedom structural systems (Charney, 2003), may be used for learning the concepts of earthquake engineering, particularly as related to structural dynamics, damping, ductility, and energy dissipation. / Master of Science

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2003. / No abstract available

As vast networks of high pressure buried energy pipelines traverse North America and other continents, the stability of such essential buried infrastructure must be maintained under a variety of earth loading conditions. The pipe-soil interaction and the longitudinal behaviour of buried pipes due to relative ground movements is poorly understood. This thesis presents full scale testing and numerical modeling of steel and Glass Fibre Reinforced Polymer (GFRP) pipelines to better understand the flexural performance of buried pipes subjected to lateral earth movement. For the experimental phase of the study, a series of pipe bending experiments have been conducted on 102 mm nominal diameter and 1830 mm long steel and GFRP pipes buried in dense sand. Pipe loading was carried out by pulling pipe ends using two parallel cables attached to a spreader beam outside the test region, using a hydraulic actuator. The different tests covered burial depth-to-diameter (H/D) ratios of 3, 5 and 7. During the steel pipe testing phase, special consideration was given to assess the effect of boundary limits, friction within the pulling mechanism, and consistency of results using repeated tests. For the GFRP pipes, the experimental work investigated the effect of the laminate structure of the pipes, including both cross-ply and angle-ply laminates. Test results showed that burial depth significantly influenced the ultimate pulling forces, longitudinal strains, and pipe net deflection at mid-span. The results were also compared between the two types of pipes. The failure mechanism for all tests was consistently governed by soil failure, except for the angle-ply GFRP pipe that failed at a burial depth of H/D=7. For the numerical analysis, the study presents the development and verification of two and three-dimensional numerical models including material constitutive models for both the pipe and for the soil using a stress-dependent modulus. Calculations are presented for different burial depths and are compared to experimental data. It was shown that the numerical model can successfully capture the pipe-soil interaction behaviour for both pipe types in terms of load-displacement responses and net bending deflection. Also, the effect of material variation and laminate structure were in agreement with test data. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2013-04-18 22:21:53.025

Orientador: Gustavo Luiz Chagas Manhães de Abreu / Resumo: O presente trabalho propõe uma nova estratégia para supressão ativa robusta do fenômeno Ground Resonance (GR) em Helicópteros. O modelo clássico de análise deste fenômeno é desenvolvido para um rotor isotrópico e a análise de estabilidade é feita no domínio de Coleman, para encontrar as fronteiras de instabilidade. Também é proposta uma nova estratégia para lidar com essas fronteiras de instabilidade e suprimir o GR usando controladores com formulação descrita por conjuntos politópicos convexos. Controladores são projetados via desigualdades lineares matriciais (LMIs, Linear Matrix Inequalities), formulados de acordo com a Teoria de Estabilidade de Lyapunov. Adicionalmente, incertezas paramétricas na frequência de lead-lag das pás e a apresentação de uma falha estrutural nos atuadores são consideradas e, assim, novos controladores robustos são projetados a fim de expandir o envelope operacional da aeronave. Ainda, são considerados diferentes tipos de não-linearidades estruturais na rigidez e amortecimento do trem de pouso do helicóptero e a caracterização da estabilidade não-linear do sistema exibe oscilações em ciclo limite (LCO, Limit Cycle Oscillation), que são determinadas a partir da construção de Diagramas de Bifurcação. Utiliza-se a modelagem Fuzzy-TS do sistema para cada caso de estudo e, com base nas fronteiras de estabilidade não-linear do GR, definidas a partir dos Diagramas de Bifurcação, têm-se o projeto de controladores para supressão das LCOs do sistema. Os res... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The present work proposes a new strategy for robust active suppression of Ground Resonance (GR) phenomenon in Helicopters. The classical model to analysis of this phenomenon is developed for an isotropic rotor and stability analysis is done in Coleman domain, to nd the boundaries of instability. It is also proposed a new strategy for dealing with these boundaries of instability and suppressing GR using controllers with polytopic convex hulls formulation. Controllers are designed via Linear Matrix Inequalities (LMIs), formulated according to the Lyapunov Stability Theory. Additionally, parametric uncertainties in the lead-lag frequency of the blades and actuators faults are considered and thus new robust controllers are designed to expand the aircraft operating envelope. Also, di erent types of structural nonlinearities in the landing gear sti ness and damping of the helicopter are considered, and the characterization of the nonlinear stability of the system exhibits Limit Cycle Oscillation (LCO), which are determined from the construction of Bifurcation Diagrams. Fuzzy-TS modeling is used for each case study and, based on the nonlinear stability boundaries of the GR, de ned from the Bifurcation Diagrams, the controllers to suppress the LCO are designed. The results of numerical simulations, discussions and conclusions are presented and show that the control strategy proposed is an attractive solution to suppress the linear and nonlinear GR problem, being able to expand the o... (Complete abstract click electronic access below) / Doutor

Na primeira parte do trabalho estudamos a equação de Schrödinger logarítmica com um delta potencial; $V(x)=-\\gamma \\,\\delta(x)$, onde $\\delta$ é a distribuição de Dirac na origem e o parâmetro real $\\gamma$ descreve a intensidade do potencial. Estabelecemos a existência e unicidade das soluções do problema de Cauchy associado em um espaço de funções adequado. No caso do potencial atrativo ($\\gamma>0$), calculamos de forma explícita o seu único ground state e mostramos a sua estabilidade orbital.\\\\ A segunda parte trata detalhadamente da equação de Schrödinger logarítmica com um delta derivada potencial; $V(x)=-\\gamma\\, \\delta^{\\prime}(x)$. A boa colocação global para o problema de Cauchy é verificada em um espaço de funções adequado. No caso do potencial atrativo ($\\gamma>0$), o conjunto dos ground states é completamente determinado. Mais precisamente: se $0<\\gamma\\leq2$, então há um único ground state e é uma função ímpar; se $\\gamma>2$, então existem dois ground states não-simétricos. Em adição, provamos que cada ground state é orbitalmente estável através de uma abordagem variacional. Finalmente, usando a teoria de extensão de operadores simétricos, também mostramos um resultado de instabilidade para $\\gamma>2$. / The first part of this thesis deals with the logarithmic Schrödinger equation with a delta potential; $V(x)=-\\gamma \\,\\delta(x)$, where $\\delta$ is the Dirac distribution at the origin and the real parameter $\\gamma$ is interpreted as the strength of the potential. We establish the existence and uniqueness of the solutions of the associated Cauchy problem in a suitable functional framework. In the attractive potential case ($\\gamma>0$), we explicitly compute the unique ground state and we show their orbital stability .\\\\ The second part deals with the case of the logarithmic Schrödinger equation with a delta prime potential; $V(x)=-\\gamma\\, \\delta^{\\prime}(x)$. Global well-posedness is verified for the Cauchy problem in a suitable functional space. In the attractive potential case ($\\gamma>0$), the set of the ground state is completely determined. More precisely: if $0<\\gamma\\leq2$, then there is a single ground state and it is an odd function; if $\\gamma>2$, then there exist two non-symmetric ground states. Moreover, we show that every ground state is orbitally stable via a variational approach. Finally, by applying the theory of extensions of symetric operators, we also prove a result of instability for $\\gamma>2$.