The aim of the project is to analyze the enlargement of the district heating line located in Gävle, evaluating the hydraulic facilities and calculating the heat losses with different insulation thicknesses to choose the best insulation thickness for the pipes. To choose the best thickness, different insulation thicknesses have been evaluated calculating the heat losses for each insulation thickness. To manage the heat losses problem, the pipe length has been divided into three stretches, underground pipe, sea pipe and air pipe. These three stretches have different boundary conditions, and each stretch has been calculated separately. The best thermal solution is choosing the insulation of 0.5m of thickness, but the best thermal solution is not the best solution for this project due to the elevated cost of this thickness in one of the stretches of the line. The pipe crossing the seahas to be on the bottom and to keep the pipe on the bottom concrete is going to be added. The quantity of concrete needed depends on the floatability of the pipe and specifically depends on the insulation thickness. The insulation is a porous material and its density is very small, therefore it has a high floatability. The final selection is a multi-thickness insulation, with different insulation thicknesses in the different stretches, 0.6m of thickness in the underground and air pipe and 0.3m of thickness in the sea pipe. With this configuration the heat losses are quite close to the optimum case. The purpose in the hydraulic study has been quantifying the start pressure in the new line to fulfil the energy demand in the worst point of the line. With 320kPa at the start of line, the pressure in the worst point is enough to fulfil the nowadays demand, 3MW, and in the future when this line will be enlarged and the demand increased to 20MW, the pressure at the start of the line to ensure the requested pressure of 250kPa in the worst point should reach more than 380kPa. Having such pressure is not recommended to avoid the pressure hammer and to build a new pumping station after the sea pipe is recommended.

<p>Heat transfer from building foundations varies significantly in all three spatial dimensions and has important dynamic effects at all timescales, from one hour to several years. With the additional consideration of moisture transport, ground freezing, evapotranspiration, and other physical phenomena, the estimation of foundation heat transfer becomes increasingly sophisticated and computationally intensive to the point where accuracy must be compromised for reasonable computation time. The tools currently available to calculate foundation heat transfer are often either too limited in their capabilities to draw meaningful conclusions or too sophisticated to use in common practices. This work presents Kiva, a new foundation heat transfer computational framework. Kiva provides a flexible environment for testing different numerical schemes, initialization methods, spatial and temporal discretizations, and geometric approximations. Comparisons within this framework provide insight into the balance of computation speed and accuracy relative to highly detailed reference solutions. The accuracy and computational performance of six finite difference numerical schemes are verified against established IEA BESTEST test cases for slab-on-grade heat conduction. Of the schemes tested, the Alternating Direction Implicit (ADI) scheme demonstrates the best balance between accuracy, performance, and numerical stability. Kiva features four approaches of initializing soil temperatures for an annual simulation. A new accelerated initialization approach is shown to significantly reduce the required years of presimulation. Methods of approximating three-dimensional heat transfer within a representative two-dimensional context further improve computational performance. A new approximation called the boundary layer adjustment method is shown to improve accuracy over other established methods with a negligible increase in computation time. This method accounts for the reduced heat transfer from concave foundation shapes, which has not been adequately addressed to date. Within the Kiva framework, three-dimensional heat transfer that can require several days to simulate is approximated in two-dimensions in a matter of seconds while maintaining a mean absolute deviation within 3%.

<p> The building sector consumes about 40% of energy used in the United States and is responsible for nearly 40% of greenhouse gas emissions. Energy reduction in this sector by means of cost-effective and scalable approaches will have an enormous economic, social, and environmental impact. Achieving substantial energy reduction in buildings may require to rethink the entire processes of design, construction, and operation of buildings. This thesis focuses on advanced control system design for energy efficient commercial buildings. </p><p> Commercial buildings are plants that process air in order to provide comfort for their occupants. The components used are similar to those employed in the process industry: chillers, boilers, heat exchangers, pumps, and fans. The control design complexity resides in adapting to time-varying user loads as well as occupant requirements, and quickly responding to weather changes. Today this is easily achievable by over sizing the building components and using simple control strategies. Building controls design becomes challenging when predictions of weather, occupancy, renewable energy availability, and energy price are used for feedback control. Green buildings are expected to maintain occupants comfort while minimizing energy consumption, being robust to intermittency in the renewable energy generation and responsive to signals from the smart grid. Achieving all these features in a systematic and cost-effective way is challenging. The challenge is even greater when conventional systems are replaced by innovative heating and cooling systems that use active storage of thermal energy with critical operational constraints.</p><p> Model predictive control (MPC) is the only control methodology that can systematically take into account future predictions during the control design stage while satisfying the system operating constraints. This thesis focuses on the design and implementation of MPC for building cooling and heating systems. The objective is to develop a control methodology that can 1) reduce building energy consumption while maintaining indoor thermal comfort by using predictive knowledge of occupancy loads and weather information, (2) easily and systematically take into account the presence of storage devices, demand response signals from the grid, and occupants feedback, (3) be implemented on existing inexpensive and distributed building control platform in real-time, and (4) handle model uncertainties and prediction errors both at the design and implementation stage.</p><p> The thesis is organized into six chapters. Chapter 1 motivates our research and reviews existing control approaches for building cooling and heating systems. </p><p> Chapter 2 presents our approach to developing low-complexity control oriented models learned from historical data. Details on models for building components and spaces thermal response are provided. The thesis focuses on the dynamics of both the energy conversion and storage as well as energy distribution by means of heating ventilation and air conditioning (HVAC) systems.</p><p> In Chapter 3, deterministic model predictive control problems are formulated for the energy conversion systems and energy distribution systems to minimize the energy consumption while maintaining comfort requirement and operational constraints. Experimental and simulative results demonstrate the effectiveness of the MPC scheme, and reveal significant energy reduction without compromising indoor comfort requirement.</p><p> As the size and complexity of buildings grow, the MPC problem quickly becomes computationally intractable to be solved in a centralized fashion. This limitation is addressed in Chapter 4. We propose a distributed algorithm to decompose the MPC problem into a set of small problems using dual decomposition and fast gradient projection. Simulation results show good performance and computational tractability of the resulting scheme.</p><p> The MPC formulation in Chapter 3 and 4 assumes prefect knowledge of system model, load disturbance, and weather. However, the predictions in practice are different from actual realizations. In order to take into account the prediction uncertainties at control design stage, stochastic MPC (SMPC) is introduced in Chapter 5 to minimize expected costs and satisfy constraints with a given probability. In particular, the proposed novel SMPC method applies feedback linearization to handle system nonlinearity, propagates the state statistics of linear systems subject to finite-support (non Gaussian) disturbances, and solves the resulting optimization problem by using large-scale nonlinear optimization solvers.</p>

Thèse (Ph.D.)--Université de Sherbrooke (Canada), 2008. / Titre de l'écran-titre (visionné le 1 février 2007). In ProQuest dissertations and theses. Publié aussi en version papier.

<p> With increasing penetrations of solar photovoltaic (PV) power in the electricity grid, the variability of the irradiance, and therefore power, is important to understand because variable resources can challenge grid operations. The smoothing of solar irradiance over the extent of PV power plants is examined using two methods: averaging measurements from many irradiance sensors, and using a model developed by Lave, Kleissl, and Stein (2013) called the Wavelet Variability Model. This thesis utilizes data from a network of 45 solar irradiance sensors which was deployed north of Flagstaff, Arizona. The results show the similarities and differences between two irradiance smoothing methods. These two models both show that the smoothing effect is significant for large PV power plants, which means the power plant output has less variability and is easier to integrate into the electricity grid than might have been expected using a single point sensor measurement to predict variability.</p>

Currently, gait rehabilitation for gait deviations associated with stroke has focused on task-specific repetitive rehabilitation techniques. Body weight supported treadmill training has been used to administer this type of rehabilitation but is labor intensive for therapists. To alleviate the burden on therapists, mechanized or robotic gait trainers have been used to elicit gait-like movements. This study is focused on evaluating an elliptical trainer that was modified to provide an ankle articulation pattern similar to that found in normal gait. The kinematic, kinetic, and metabolic effect of the modifications on normal subjects was evaluated. Eight healthy adult subjects (4 male, 4 female; mean age 28.6 ± 5.2) participated in this research. Subjects were asked to ambulate on the elliptical trainer with and without the modifications at two metronome-paced speeds (1Hz and 1.5Hz). Video-based motion analysis techniques were used to collect sagittal plane kinematic data at a rate of 30 Hz. Reflective markers were placed over the acromion, greater trochanter, fibular head, lateral malleolus, heel, and fifth metatarsal. Metabolic Energy – The rate of energy consumption (VO2 consumption and VCO2 production) was measured using ventilatory expired gas analysis (SensorMedics, Yorba Linda, CA). The articulation of the footplate on the modified elliptical trainer correlated with the foot movement seen in normal ambulation (r2=0.89). It was found that for the ankle and knee, the joint angles while ambulating on the modified elliptical trainer correlated better to normal gait than the non-modified elliptical trainer. However, the hip angles were found to correlate worse. This suggests that the ankle articulation was successful, but the distal control was not as effective as expected. Kinetic energy was found to not be significantly different between the modified elliptical trainer and the non-modified elliptical trainer. Metabolic energy was found to be statistically higher on the modified elliptical trainer (p=0.001). This may suggests that there is co-contraction of muscles around joints. Further study using electromyography may provide further insight on the difference seen in metabolic energy consumption.

Detta examensarbete har genomförts på Volvo Aero i Trollhättan och består av tre delar: en kartläggning av processventilationens uppbyggnad på ett antal utvalda maskiner och beräkning av dess energiåtgång, en jämförelse ur energieffektivitetssynpunkt mellan ett nyutvecklat maskinkoncept som kallas MultiTask-Cell och traditionell tillverkning, sist har en tomgångsanalys gjorts i verkstaden för att identifiera vad som använder elenergi då ingen produktion sker. För att kunna genomföra uppgifterna har mätningar av elanvändningen gjorts på både maskinnivå och transformatorer, detta för att kunna beräkna energianvändning på utvalda maskiner och även få en helhetssyn över verkstadens energianvändning. Det har även gjorts datainsamling och intervjuer för att få grepp över processventilationens funktion och uppbyggnad. Det finns två varianter på processluften, ett där konstant relativt högt luftflöde används och ett när man genom varvtalsreglering av fläkten använder ett lägre grundflöde som forceras en viss tid vid spindelstopp. Ur energisynpunkt är metoden med grundflöde och forcering att föredra då det leder till både mindre energiförluster genom processluften och en stor minskning av fläktens elbehov. Det har även räknats ut en teoretisk energibesparing vid införande av värmeåtervinning för två maskingrupperingar. Jämförelsen mellan MultiTask-cellen och traditionella maskiner har gjorts genom att mäta den energi det krävs för att tillverka en detalj för respektive tillverkningssätt. MultiTask-cellen visade sig använda cirka 25 % mindre energi än de traditionella maskinerna för tillverkning av samma typ av detalj. Tomgångsanalysen visar på ett högt effektuttag även då det ej sker någon produktion på Volvo Aero. Detta beror till stor del på att maskinerna har en relativt hög tomgångsförbrukning. Denna krävs för att hålla maskinen varm vilket ger en så problemfri uppstart som möjligt. Att byta ut allmänbelysningens armatur till nyare och modernare skulle årligen ge en betydande energibesparing.

Simulation is one of the best Analytical tools for Building Research .Energy Efficient Buildings are of great concern which is gaining importance steeply in this energy scarcity’s world. Selected for the thesis work is a small Office building (Mariannelund), located in Jönköping. The building is single-storied with 26 rooms. The study motive involves Energy Survey and to provide, investigate Energy conservation measures. The Energy simulation software used is the IDA indoor climate and energy 3.0. (ICE).Data included was from the provided (Specifications) and with the review of architectural drawings. Energy saving measures was analyzed, documented with respect to their feasibility and practical operational strategies. Measures concerning the modifications in the building envelope; retrofit insulation, shading devices and other improvements leading to savings of energy have been tested and are supplemented with results. The Proposed Model which is with the combined Energy saving measures yields annual energy savings of about 70% and also working efficiency is increased by 37% compared to the existing building’s Baseline model.Considering the economic aspects together with the thermal response of employees the analyzed energy saving measures are highly recommended.

<p>Detta examensarbete har genomförts på Volvo Aero i Trollhättan och består av tre delar: en kartläggning av processventilationens uppbyggnad på ett antal utvalda maskiner och beräkning av dess energiåtgång, en jämförelse ur energieffektivitetssynpunkt mellan ett nyutvecklat maskinkoncept som kallas MultiTask-Cell och traditionell tillverkning, sist har en tomgångsanalys gjorts i verkstaden för att identifiera vad som använder elenergi då ingen produktion sker.</p><p>För att kunna genomföra uppgifterna har mätningar av elanvändningen gjorts på både maskinnivå och transformatorer, detta för att kunna beräkna energianvändning på utvalda maskiner och även få en helhetssyn över verkstadens energianvändning. Det har även gjorts datainsamling och intervjuer för att få grepp över processventilationens funktion och uppbyggnad.</p><p>Det finns två varianter på processluften, ett där konstant relativt högt luftflöde används och ett när man genom varvtalsreglering av fläkten använder ett lägre grundflöde som forceras en viss tid vid spindelstopp. Ur energisynpunkt är metoden med grundflöde och forcering att föredra då det leder till både mindre energiförluster genom processluften och en stor minskning av fläktens elbehov. Det har även räknats ut en teoretisk energibesparing vid införande av värmeåtervinning för två maskingrupperingar.</p><p>Jämförelsen mellan MultiTask-cellen och traditionella maskiner har gjorts genom att mäta den energi det krävs för att tillverka en detalj för respektive tillverkningssätt. MultiTask-cellen visade sig använda cirka 25 % mindre energi än de traditionella maskinerna för tillverkning av samma typ av detalj.</p><p>Tomgångsanalysen visar på ett högt effektuttag även då det ej sker någon produktion på Volvo Aero. Detta beror till stor del på att maskinerna har en relativt hög tomgångsförbrukning. Denna krävs för att hålla maskinen varm vilket ger en så problemfri uppstart som möjligt. Att byta ut allmänbelysningens armatur till nyare och modernare skulle årligen ge en betydande energibesparing.</p>

Submitted by MAYARA ALINE BALLER null (mayara.baller@hotmail.com) on 2018-03-27T18:13:55Z No. of bitstreams: 1 Dissertação_Mayara_Aline_Baller.pdf: 1097419 bytes, checksum: 1ed29fabe4f9766088f4c08034fb44bb (MD5) / Rejected by Alexandra Maria Donadon Lusser Segali null (alexmar@fcav.unesp.br), reason: Solicitamos que realize correções na submissão seguindo as orientações abaixo: No arquivo pdf submetido ao repositório não consta o certificado de aprovação (parte obrigatória). Peço o favor de inserir o mesmo no arquivo pdf e posteriormente faça uma nova submissão. Agradecemos desde já a compreensão. on 2018-03-28T12:44:35Z (GMT) / Submitted by MAYARA ALINE BALLER null (mayara.baller@hotmail.com) on 2018-04-02T19:57:16Z No. of bitstreams: 1 Definitivo_Mayara_Aline_Baller.pdf: 1118401 bytes, checksum: a6ef83398402780f3bf51364be72e883 (MD5) / Approved for entry into archive by Alexandra Maria Donadon Lusser Segali null (alexmar@fcav.unesp.br) on 2018-04-03T10:44:39Z (GMT) No. of bitstreams: 1 baller_ma_me_jabo.pdf: 1118401 bytes, checksum: a6ef83398402780f3bf51364be72e883 (MD5) / Made available in DSpace on 2018-04-03T10:44:39Z (GMT). No. of bitstreams: 1 baller_ma_me_jabo.pdf: 1118401 bytes, checksum: a6ef83398402780f3bf51364be72e883 (MD5) Previous issue date: 2017-02-23 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A adição de água é uma das variáveis que otimiza o processo de extrusão, uma vez que favorece o umedecimento dos ingredientes e transferência de calor, proporcionando o cozimento adequado; ocasiona mudanças na viscosidade e nas características macroestruturais dos kibbles reduzindo o desgaste da rosca extrusora; e se adicionada em quantidades suficientes, diminui a taxa de ocorrência da reação de Maillard. Apesar de sua importância, não se localizaram estudos sobre os melhores intervalos de umidade de processamento para a produção de rações para gatos. O objetivo deste trabalho foi avaliar os efeitos da umidade da massa no canhão da extrusora sobre os parâmetros de processamento, macroestrutura dos kibbles, balanço de massa e energia, gelatinização do amido e teor de lisina reativa em alimentos extrusados para gatos. Uma fórmula padrão para gatos foi extrusada, e durante o processo de extrusão foram adicionadas seis diferentes quantidades de água no canhão extrusor, correspondendo as umidades da massa de 22%, 27%, 30%, 32%, 35% e 37% (tratamentos). O alimento foi produzido em extrusora de rosca simples e as condições de processamento foram estabilizadas para a dieta 22%, não sendo alteradas para as demais dietas. Os parâmetros registrados foram a temperatura do pré-condicionador, temperatura, pressão e produtividade da extrusora. Amostras de ração foram coletados a cada 15 minutos na saída da extrusora, sendo considerado cada coleta uma unidade experimental. A energia mecânica específica e a energia térmica específica, transferidas à massa, foram calculadas de acordo com Riaz (2007). A lisina reativa foi avaliada pelo método da O-metilisoureia (Moughan e Rutherfurd, 1996). Os dados obtidos foram submetidos à análise de variância (ANOVA) e as médias comparadas por contrastes polinomiais (P<0,05). A adição de água aumentou a umidade de processamento de forma linear (P<0,001), o que resultou em diminuição da pressão e temperatura de extrusão, redução quadrática da aplicação de energia mecânica específica (EME) (P<0,001), redução quadrática na densidade aparente e específica, e na expansão radial e longitudinal (P<0,01), sem alterar a força de ruptura e a gelatinização do amido das dietas. Houve ainda um aumento da lisina ligada, indicando maior complexação do aminoácido (P<0,001). Conclui-se que uma elevada umidade da massa no canhão leva à uma redução da EME, da temperatura, da pressão, da gelatinização do amido, explicado pelo aumento da fluidez da massa e consequente reduz do cisalhamento. Por outro lado, a baixa umidade da massa reduziu a expansão, a temperatura e o flash-off ou vaporização da água, fenômeno chave na formação celular e expansão do extrusado. / The addition of water is one of the variables that maximizes the extrusion process, since it favors the hydration of the ingredients and the heat transfer, providing a proper cooking; it also causes changes in the viscosity and macrostructural characteristics of the kibbles, reducing the wear of the extruder thread; if added in sufficient amounts it decreases the occurrence of Maillard reaction. Despite their importance, there are no studies evaluating the best processing moisture ranges for the production of cat food. The objective of this work was to evaluate the effects of the in-barrel moisture on the processing parameters, kibble macrostructure, mass and energy balance, starch gelatinization and reactive lysine content of extruded foods for cats. A standard formula for cats was extruded, and during the extrusion process six different amounts of water were added to the extruder barrel, corresponding to the moistures of22%, 27%, 30%, 32%, 35% and 37% (treatments).The feed was extruded in a single screw extruder and the processing conditions were stabilized for the 22% diet, they were not changed for the other diets. The productivity, pressure and temperatures of the conditioner and of the extruder were recorded. Feed samples were collected every 15 minutes at the end of the extruder, each sample was considered an experimental unit. The specific mechanical energy and specific thermal energy transferred to the mass were calculated according to Riaz (2007). The reactive lysine was evaluated by the O-methylisourea method (Moughan and Rutherfurd, 1996). The data were submitted to analysis of variance (ANOVA) and the means were compared by polynomial contrasts (P <0.05). Addition of water linearly increased the processing moisture (P <0.001), which resulted in a decrease in extrusion pressure and temperature, quadratic reduction of specific mechanical energy application (P <0.001), quadratic reduction in density apparent and specific, radial and longitudinal expansion (P <0.01), without altering the breaking strength and the starch gelatinization of the diets. There was also an increase in the bound lysine indicating greater amino acid complexation (P <0.001). It is concluded that an increase in in-barrel moisture leads to a reduction in the EME, the temperature, the pressure, the starch gelatinization, explained by the increase of the fluidity mass and consequent reduction of the shear. On the other hand, a low in-barrel moisture reduced expansion, a temperature and flash off, a key phenomenon in the cell formation and expansion of the extrudate.