Thèses sur le sujet « Mechanical ventilation system »

The trend towards improving building airtightness to save energy has increased the incidence of poor indoor air quality and associated problems, such as condensation on windows, mould, rot and fungus on window frames. Mechanical ventilation/heat recovery systems, combined with heat pumps, offer a means of significantly improving indoor air quality, as well as providing energy efficient heating and cooling required in buildings. This thesis is concerned with the development of a novel mechanical ventilation heat recovery/heat pump system for the domestic market. Several prototypes have been developed to provide mechanical ventilation with heat recovery. These systems utilise an annular array of revolving heat pipes which simultaneously transfer heat and impel air. The devices, therefore, act as fans as well as heat exchangers. The heat pipes have wire finned extended surfaces to enhance the heat transfer and fan effect. The systems use environmentally friendly refrigerants with no ozone depletion potential and very low global warming potential. A hybrid system was developed which incorporated a heat pump to provide winter heating and summer cooling. Tests were carried out on different prototype designs. The type of tinning, the working fluid charge and the number and geometry of heat pipes was varied. The prototypes provide up to 1000m3/hr airflow, have a maximum static pressure of 220Pa and have heat exchanger efficiencies of up to 65%. At an operating supply rate of 200m3/hr and static pressure 100Pa, the best performing prototype has a heat exchanger efficiency of 53%. The heat pump system used the hydrocarbon isobutane as the refrigerant. Heating COPs of up to 5 were measured. Typically the system can heat air from 0°C to 26°C at 200m3/hr with a whole system COP of 2. The contribution to knowledge from this research work is the development of a novel MVHR system and a novel MVHR heat pump system and the establishment of the performances of these systems.

This Master Studies Thesis of Quality in Process Technology deals with Process Improvement. The ventilation system of University building is dealt as a Process and is looked for improvements. The ventialtion system for two computer rooms is studied and analyzed for the variaitons in the operating conditions.

This study concerns the development of a novel mechanical ventilation system, with a view to analysing the results of a new mechanical ventilation technique, referred to noisy ventilation. Additionally, the study addresses the assessment of the system, involving the estimation of certain mechanical parameters of the respiratory system under noisy ventilation and discusses a pilot trial in vivo, with a pig. During acute respiratory failure, intubation and invasive mechanical ventilation may be life saving procedures. The general aim of mechanical ventilation is to provide adequate gas exchange support, while not damaging the respiratory system. This technique is one of the most important life support tools in the intensive care unit. However, it may also be harmful by causing ventilator induced lung injury and other undesirable effects. There is a growing interest in the development and use of variable mechanical ventilation performing variable volume and variable pressure controlled ventilation. The reasons are that this technique can improve lung functions and reduce lung damage, when compared to standard mechanical ventilation. Moreover, variable ventilation can improve lung mechanics and gas exchanges. The new ventilation system has to have the capabilities to perform a noisy ventilation regime, besides the standard mechanical ventilation. The development started with commercial devices: a mechanical ventilator and a personal computer, whose roles were to execute the noisy ventilation regime and to implement the new ventilation pattern by means of a ventilation routine, commanding the mechanical ventilator. After these two components were working together, a bench test was performed, in which a calibrated measuring device and a mechanical lung simulator were utilized. Considering that the system was working properly, it was possible to validate it by analysing the results. As the mechanical properties of the respiratory system are important quantities to know, a parameter estimation method was developed, with a view to estimating some relevant properties, such as compliance, positive end--expiratory pressure, resistance and others. The estimates were related to the adopted model for the respiratory system. In this study, four models were discussed: first order linear model, flow dependent resistance model, volume dependent elastance model and second order linear model. For each one, all parameters were estimated and the outcomes from each estimation were compared with the others, with a view to finding relationships between them and to evaluating the goodness of each model. Furthermore, as some parameters could be adjusted directly in the devices, adjusted and estimated values could also be compared. Finally, one trial in vivo was performed, with a view to assessing the behaviour of the system in a real situation and to showing the developed system to the research team. The system was set to work in a noisy and in a standard ventilation regime. It showed reasonable results in terms of quality of ventilation as well as reliability and maintainability of the ventilatory regime, during the whole test period. The developed parameter estimation methods were utilized to estimate the mechanical respiratory properties of the animal under test and to find cross relationships between these outcomes and others, such as those from blood gas, ultrasonography and electrical impedance tomography.

The building sector is responsible for 36% of the energy usage and 39 % of all CO2- emissions in European union (EU). Therefore, it is of great interest to investigate how the building sector can become more energy efficient and lower the environmental impact. It is reported that 80-90 % of a building’s total energy usage occurs during the operational phase. The energy usage is mainly due to lightning, technical equipment and the heating, cooling and ventilation system (HVAC-system). During the last century the energy efficiency in lightning developed significantly meaning the energy used in the HVAC-system becomes increasingly significant. As EU aim to increase the energy efficiency and the ratio of renewable energy in the grid, one can assume that the importance of other phases in the HVAC system lifecycle will be increasingly interesting as for example the manufacturing process and material usage which can be evaluated through life cycle assessment (LCA).This thesis presents a comparison between the environmental impacts of a hybrid ventilation (HV) system and a mechanical ventilation system with heat recovery (MVHR) system through a LCA perspective designed for an office building in Lystrup, Denmark. The office building in Lystrup, Denmark was chosen as the HV system is implemented there. The HV system consists of an automated natural ventilation (NV) system and a mechanical exhaust air ventilation (MEV) system. The environmental impact from the NV was provided through environmental products declarations provided by the company dimensioning the NV system. The data was lacking for the MEV system and that system was therefore dimensioned and evaluated through LCA. The mechanical ventilation system chosen for comparison is a mechanical ventilation system with heat recovery (MVHR) decided by the commissioner of the project, Sweco AB. The MVHR system was dimensioned as well. The project was significantly affected by lack of data resulting in many assumptions. The system boundary of the life cycle was set to cradle to grave excluding the energy usage of producing the ventilation components. The assumed lifetime is 25 years. Gabi Education software was used for calculating the LCA results. The impact categories chosen are global warming potential (GWP), ozone depletion potential (ODP), acidification potential (AP), eutrophication potential (EP), photochemical ozone depletion potential (PODP), abiotic depletion potential (ADP) elements and ADP fossil which are used in the EN15804 standard when conducting LCA for construction components. The CML2001-IA 2001 IA method was used for the life cycle impact assessment in the LCA software which also is recommended according to EN15804.The LCA results were compared between the systems and interpreted through contribution analysis were the result was divided in the following categories; Energy usage (use phase), transportation, material usage (including raw material extraction and material processing) and end of life treatment. The two systems score similarly on all environmental impacts categories except for the global warming potential (GWP) and the abiotic depletion potential (ADP) fossil were the MVHR system scores approximately 3 times higher than the HV system. The MVHR system consumes approximately 3 times more energy during the use phase. The contribution analysis showed that the energy usage (use phase) dominated the contribution in almost all environmental impact categories. Further, the environmental impact caused by the material usage was compared between the MVHR - and HV system and the MVHR system scored higher in all categories except ADP elements.The conclusion drawn from this report is that the HV system is better if one looks to GWP and ADP fossil. The HV contributes less to climate change which is an important environmental concern. Further, the energy usage during use phase contributed most to environmental impacts for both the MVHR - and HV system. The environmental impact of the material usage is less for the HV - compared with the MVHR system.
Byggnadssektorn står för 36 % av energianvändningen och 39 % av alla koldioxidutsläpp i Europeiska unionen (EU). Därför är det av stort intresse att undersöka hur byggsektorn kan bli mer energieffektiv och undersöka hur dess miljöpåverkan kan minskas. Det rapporteras att 80–90 % av en byggnads totala energianvändningen inträffar under driftsfasen. Energianvändningen beror främst på belysning och värme-, kyla- och ventilationssystemet (VVS-systemet). Under det sista århundradet har energieffektiviteten gällande belysning förbättrats avsevärt, vilket innebär att betydelsen för energianvändningen till VVS-systemet ökat. Eftersom EU strävar efter att öka energieffektiviteten och mängden förnybar energi i elnätet kan man anta att betydelsen av andra faser i VVS-systemets livscykel kommer att bli allt mer intressant, till exempel tillverkningsprocessen och materialanvändningen vilket kan utvärderas genom livscykelanalys (LCA).   Denna rapport jämför miljöpåverkan från ett hybridventilationssystem (HV) med ett mekaniskt ventilationssystem med värmeåtervinningssystem (FTX-system) ur ett LCA-perspektiv. Studien utförs på kontorsbyggnad i Lystrup, Danmark. Kontorsbyggnaden i Lystrup valdes eftersom ett HV-systemet är implementerat där. HV-systemet består av ett automatiserat naturligt ventilationssystem (NV) och ett mekaniskt frånluftsventilationssystem (F-system). Miljöpåverkan från det NV-systemet tillhandahölls ur miljöproduktdeklarationer (EPD:er) som dimensioneringsföretaget tillhandahöll. Uppgifterna saknades för F-systemet och därför dimensionerades det förhand för att sedan utvärderades genom LCA. Hv-systemet jämfördes mot ett FTX system vilket bestämdes av uppdragsgivaren på företaget Sweco AB. FTX-systemet dimensionerades också förhand för att sedan utvärderas genom LCA. Livscykelns systemgräns sattes till från ”vagga-till-grav” exklusive energianvändningen för att producera ventilationskomponenterna då denna data saknades. Den antagna livslängden för ventilationssystemen är 25 år. LCA programvaran Gabi Education användes för att beräkna LCA resultaten. De miljöpåverkanskategorier som undersökts i den här studien är: global uppvärmningspotentialen, ozonuttunnande potential, försurningspotential, eutrofieringspotential, fotokemisk ozonuttunningspotential, abiotisk utarmningspotential (material) och abiotisk utarmningspotential (fossila bränslekällor) vilka skall användas enligt EN15804-standarden då LCA:er utförs på byggkomponenter. CML2001-IA metoden användes som livscykelkonsekvensbedömningen LCA-programvaran, vilket också rekommenderas enligt EN15804.   LCA-resultaten jämfördes mellan systemen och tolkades genom en bidragsanalys där resultatet delades in i följande kategorier: Energianvändningen (användningsfas), transport, materialanvändning (inklusive råvaruutvinning och materialbearbetning) och slutanvändningsfasen för komponenterna. De två systemen var likvärdiga i de flest miljöpåverkanskategorier utom den globala uppvärmningen potential och abiotiska utarmning potential fossil där FTX-systemet bidrog med ungefär 3 gånger så hög potentiell påverkan än det HV-systemet. FTX-systemet förbrukar ungefär 3 gånger mer energi under användningsfasen. Bidragsanalysen visade att energianvändningen (under användningsfasen) var den dominerade faktorn i nästan alla kategorier av miljöpåverkan. Utöver denna analysen jämfördes miljöpåverkan orsakad av materialanvändningen mellan FTX - och HV-systemet, där FTX-systemet fick högre poäng i alla kategorier utom i abiotiska utarmnings potential (material).   Slutsatsen från den här studien är att det HV-systemet är bättre om man ser till global uppvärmningspotential och abiotisk utarmningspotential fossil. Det HV-system har alltså mindre potential till att bidra till klimatförändringar och mindre potential att utarma fossila bränslekällor. Enligt den här studien är energianvändningen under användningsfasen den faktor som bidrar mest till miljöpåverkanskategorierna för både FTX - och det HV-systemet. Miljöpåverkan orsakad av materialåtgången är mindre för det HV-systemet än FTX systemet.

Mechanical ventilators are devices in critical care to assist breathing in case of expiratory dysfunction. The expiratory valve is a critical component to the ventilator as it controls the pressure in the patient’s lungs. The design process of a new expiratory valve assembly is a time consuming one due to the wide range of possible design solutions both the voice-coil actuators and membrane valves typically used in ventilators. This thesis evaluates the possibility of creating and using analytical models for model based development to speed up the early design phases of a expiratory valve assembly. The main components, voice-coil actuator and membrane valve are modelled separately and experimentally verified. A complete expiratory system model and hardware-in-the-loop test setup are constructed in order to explore how well can the dynamic properties and control performance of valve assembly be predicted. Finally various questions in the valve assembly design are explored and a new design is proposed to demonstrate the capabilities of the model based approach. The resulting voice-coil and membrane valve models can be considered accurate enough for fast exploration of the design space, as an error rate below 10% is reached without manual tuning for each design.
Mekaniska ventilatorer är en utrustning inom intensivvården för assisterad andning för patienter med nedsatt andningsförmåga. Utandningsventilen är en kritisk komponent till ventilatorn då den kontrollerar lungtrycket hos patienten. Design processen för en ny utandningsventil är en tidskrävande process mycket på grund av den mängd olika design möjligheter som kan utforskas för både talspole aktuatorn samt membran ventilen som oftast används i ventilatorerna. I detta examensarbete utforskades möjligheterna till att skapa och använda analytiska modeller för modellbaserad utveckling för att accelerera de tidiga design stadierna för en utandningsventil. Huvudkomponenterna, talspole aktuatorn och membran ventilen är modellerade separat och experimentellt verifierade. En fullständig modell för hela utandningssystemet samt en hardware-in-the-loop test plattform är konstruerad för att utforska hur väl de dynamiska egenskaperna samt kontroll prestandan för en utandningsventil kan prediceras. Slutligen utforskas diverse frågor angående ventil designen och en ny design föreslås för att demonstrera möjligheterna med en modellbaserad metod. Den slutliga modellen för både talspole aktuatorn och membran ventilen kan betraktas som tillräcklig precisa för snabb utforskning inom de olika design möjligheterna, då en felprocent under 10% är uppnådd utan manuell finjustering för varje design.

Severe infections, trauma or major surgery can each cause a state of systemic inflammation. These causes for systemic inflammation often coexist and complicate each other. Mechanical ventilation is commonly used during major surgical procedures and when respiratory functions are failing in the intensive care setting. Although necessary, the use of mechanical ventilation can cause injury to the lungs and other organs especially under states of systemic inflammation. Moreover, a course of mechanical ventilator therapy can be complicated by ventilator-associated pneumonia, a factor greatly influencing mortality. The efforts to avoid additional ventilator-induced injury to patients are embodied in the expression ‘protective ventilation’. With the use of pig models we have examined the impact of protective ventilation on systemic inflammation, on organ-specific inflammation and on bacterial growth during pneumonia. Additionally, with a 30-hour ventilator-associated pneumonia model we examined the influence of mechanical ventilation and systemic inflammation on bacterial growth. Systemic inflammation was initiated with surgery and enhanced with endotoxin. The bacterium used was Pseudomonas aeruginosa. We found that protective ventilation during systemic inflammation attenuated the systemic inflammatory cytokine responses and reduced secondary organ damage. Moreover, the attenuated inflammatory responses were seen on the organ specific level, most clearly as reduced counts of inflammatory cytokines from the liver. Protective ventilation entailed lower bacterial counts in lung tissue after 6 hours of pneumonia. Mechanical ventilation for 24 h, before a bacterial challenge into the lungs, increased bacterial counts in lung tissue after 6 h. The addition of systemic inflammation by endotoxin during 24 h increased the bacterial counts even more. For comparison, these experiments used control groups with clinically common ventilator settings. Summarily, these results support the use of protective ventilation as a means to reduce systemic inflammation and organ injury, and to optimize bacterial clearance in states of systemic inflammation and pneumonia.

Les objectifs de la thèse sont l'a nalyse approfondie d'un système de supervision automatique de la ventilation artificielle des patients hospitalisés en soins intensifs et l'élaboration de solutions pour améliorer et étendre son fonctionnement. Ce système adapte l'assistance en pression de la ventilation spontanée avec aide inspiratoire (AI) par un rétrocontrôle basé sur la fréquence respiratoire du patient et, comme variables de "sécurité", le volume courant et le CO2 de fin d'expiration (etCO2). Il établit ainsi une classification ventilatoire et règle un niveau de pression d'AI.Sur la base d'études publiées rapportant des limitations, d'analyses d'une base de données rétrospectives acquises sur patient, d'études sur banc-test et d'études observationnelles prospectives réalisées chez les patients, nous avons étudié précisément le fonctionnement du système. Pour la plupart des limitations, une solution a été proposée et évaluée sur banc. A partir d'une étude clinique, nous avons proposé une amélioration de la procédure de traitement du signal etCO2 par le système. En nous basant sur les observations de la base de données, nous avons décrit une procédure automatisée de sevrage de la PEP dont un niveau supérieur à 5 mbar entrave le sevrage par le système. Sur le même principe, nous avons souhaité, en amont de l'AI, tenter d'automatiser un changement de mode depuis la ventilation assistée contrôlée. Au travers d'une étude clinique, nous avons déterminé des critères ventilatoires qui pourraient permettre d'automatiser cette procédure. L'ensemble a permis la définition d'une méthodologie d'évaluation et d'amélioration d'un système automatisé de ventilation artificielle

Introdução: A assistência ventilatória adequada é imprescindível para o tratamento do paciente ventilado artificialmente. A busca por parâmetros para realizar o ajuste ótimo e que tenham aplicação fácil a beira leito como, por exemplo, métodos não-invasivos, são desejáveis. Objetivo: analisar a acurácia diagnóstica das variáveis do padrão respiratório, da P0.1 esofágica e traqueal, para o ajuste da assistência ventilatória em pressão de suporte. Métodos: Vinte e sete pacientes internados em unidade de terapia intensiva foram consecutivamente incluídos no estudo. Todos pacientes estavam no modo de pressão de suporte, que foi aumentada para 20 cmH2O e diminui em passos de 3 cmH2O, até 2 cmH2O ou antes se o paciente apresentasse sinais de desconforto respiratório. Os pacientes foram monitorizados com cateteres para medidas de pressão esofágica e gástrica, com uma peça proximal ao tubo para mensurar a pressão traqueal a partir da oclusão da via aérea e com um pneumotacógrafo para medidas de fluxo. Durante todos níveis de suporte, foram gravados os dados dos cateteres esofágicos, gástricos, da traquéia, dados hemodinâmicos e do padrão respiratório. O ajuste da assistência ventilatória foi classificado como adequado, insuficiente e excessivo de acordo com critérios pré-estabelecidos. Resultados: Foram analisados 210 períodos com diferentes pressões de suporte e em 49% destes períodos a assistência foi excessiva, enquanto em 3,8% a assistência foi insuficiente. No início do estudo, enquanto os pacientes ainda estavam com a assistência ventilatória ajustada pela equipe assistente, 48,2% apresentavam assistência ventilatória excessiva. Pela pequena incidência de períodos com assistência ventilatória insuficiente, não foi avaliado a acurácia das variáveis para diagnóstico de assistência insuficiente. Para diagnosticar assistência ventilatória excessiva, a variável do padrão respiratório que se mostrou mais acurada foi a frequência respiratória, com sensibilidade de 90% e especificidade de 88% quando a frequência respiratória foi menor que 17 incursões por minuto. Outras variáveis do padrão respiratório não mostraram elevada acurácia. Também para o diagnóstico de assistência excessiva, foi elevada a acurácia da P0.1 esofágica (sensibilidade de 81% e especificidade de 70% quando P0.1 <= 1,9) e da P0.1 traqueal (sensibilidade de 81% e especificidade de 70% quando P0.1 <= 2,1). Conclusão: A ocorrência de assistência ventilatória excessiva foi significativamente maior que a assistência ventilatória insuficiente. A frequência respiratória menor que 17 foi a variável do padrão respiratório com maior acurácia para diagnosticar assistência ventilatória excessiva. As P0.1 esofágica e traqueal também tiveram acurácia elevas, mas menores que a frequência respiratória .
Introdution: The adequate assistance is essential for the treatment of mechanically ventilated patient. The search of parameters to achieve the optimal adjustment and with easy application to bedside, for example, non-invasive methods. Objective: Analyze the diagnostic accuracy of the breathing pattern variables, esophageal and tracheal P0.1 for adjustment of mechanical ventilation in pressure support ventilation. Methods: Twenty-seven patients in intensive care unit were consecutively included in the study. All patients were in the pressure support mode, which was raised to 20 cmH2O and decreased in steps of 3 cmH2O up to 2 cmH2O or earlier if the patient had signs of respiratory distress. Patients were monitored with catheters for esophageal and gastric pressure measurements, with the T-piece was used close to the tube to measure tracheal pressure during an airway occlusion and a pneumotachograph for flow measurements. Data was recorded for all support levels to esophageal, gastric, and tracheal pressures, also hemodynamic data and ventilatory pattern. The adjustment of mechanical ventilation was classified as adequate assistance, overassistance and underassistance according to pre-established criteria. Results: Two hundred and ten periods were analyzed with different pressures of support and 49% of these periods were overassistance, while 3,8% these periods were underassistance. At baseline, while patients were still ventilatory assistance set by assistance staff, 48,2% had overassistance. Due to the low incidence of periods with underassistance, the variables accurancy has not been evaluated. The variable breathing pattern that was more accurate diagnosing overassistance was the respiratory rate (90% sensitivity and specificity of 88 % when the respiratory rate was less than 17 breaths per minute). Other variables of the breathing pattern did not show high accuracy although esophageal P0.1 (sensitivity 81 % and specificity of 70 % when P0.1 <= 1,9) and tracheal P0.1 (sensitivity 81 % and specificity of 70 % when P0.1 <= 2,1) were high accuracy diagnosing overassistance. Conclusion: The occurrence of overassistance was significantly higher than underassistance. The respiratory rate below 17 was the variable breathing pattern more accurate to predict overassistance. The esophageal and tracheal P0.1 also had high accuracy but lower than the respiratory rate

This work presents the results of different numerical and experimental studies about energy performance, thermal comfort and ventilation effectiveness of radiant systems combined with different types of mechanical ventilation. Experimental studies have been carried out in Italy, in a test room in the laboratories of the company RHOSS S.p.A in Codroipo (Udine) and in Denmark, in a test room in the laboratories of the International Centre for Indoor Environment and Energy (ICIEE), at DTU (Danish Technical University), in Lyngby. Radiant systems in residential and in office buildings are increasingly used because of the low heating or cooling demand and, at the same time, for the good thermal comfort they assure. The thermal output estimation of radiant system in steady state condition needs the determination of the convective heat transfer coefficient from the surface to the room; a critical review among the correlations available in literature have been carried out and correlations for heated ceiling and cooled floor have been presented. Furthermore the variation of convective heat transfer coefficients, depending on the considered ventilation systems, has been estimated by means of the Computational Fluid Dynamics (CFD) technique. The energy performance and thermal behavior of radiant systems during transient conditions have been predicted by using experimental tests and numerical calculations with the software Digithon that was developed by the University of Padua. In this work the validation of this software by comparison with experimental data has been presented. In new and renovated buildings the high tightness and high insulation determine a potential risk of poor indoor air quality and condensation at the surfaces; for this reason an efficient ventilation system is necessary to provide for fresh air in the rooms. In a low polluted building air quality depends on human bioeffluents, among which carbon dioxide is considered the most significant one. By using numerical simulations (CFD) the effects of the supply and extract air terminals on contaminants distribution in offices equipped with a cooled ceiling has been investigated. Besides, in order to fully characterize the indoor climate of residential rooms or offices, an extensive experimental study has been carried out in a test room to determine both thermal comfort and ventilation effectiveness for different solutions of mixing ventilation and displacement ventilation combined with floor radiant systems. In particular, the effects of supply and extract air terminals positions by using low air change rates in mixing ventilation and the effects of different ventilation rates with displacement ventilations terminals have been analyzed. Results from experiments have been used for the validation of a CFD model for the prediction of air distribution in rooms equipped with mixed or displacement ventilation, combined with heating/cooling floor systems.
In questo lavoro di dottorato vengono presentati i risultati di uno studio sui sistemi radianti per il raffrescamento ed il riscaldamento in ambito civile e sulla loro integrazione con opportuni sistemi di ventilazione meccanica. Le prestazioni energetiche in regime stazionario e transitorio, così come le prestazioni di comfort termico e di qualità dell’aria garantita, sono state studiate mediante l’ausilio di prove sperimentali, di simulazioni fluidodinamiche e di altri codici di calcolo. Gli studi sperimentali sono stati realizzati in parte in Italia, presso i laboratori dell’azienda RHOSS S.p.A di Codroipo (Udine), e in parte presso i laboratori dell’ICIEE (International Centre for Indoor Environment and Energy), dell’Università Tecnica di Danimarca, (DTU) a Lyngby (DK). L’aspetto più rilevante di questo lavoro è legato alla sempre maggiore diffusione dei sistemi radianti come soluzione per il riscaldamento ed il raffrescamento di ambienti interni, in quanto combinano vantaggi energetici ad elevati livelli di comfort termico. Per ragioni dovute alla piccola differenza di temperatura tra l’ambiente e il fluido termovettore, i sistemi radianti si interfacciano molto bene con caldaie a condensazione, pompe di calore, sistemi free cooling, collettori solari e altre sorgenti rinnovabili e soluzioni ad alta efficienza energetica. Il calcolo della resa termica di tali sistemi viene eseguito mediante le equazioni valide per la convezione in regime stazionario, come quelle fornite dalle norme Europee EN 1264 ed EN 15377. In letteratura esistono numerose correlazioni valide per il calcolo della potenza convettiva di superfici orizzontali e verticali e di superfici interne di stanze reali; le norme EN 1264 ed EN 15377 consigliano correlazioni diverse e lo stesso accade per codici si simulazione energetica degli edifici. Ad oggi non è disponibile una chiara definizione di coefficiente di scambio termico convettivo per i sistemi radianti, specialmente per quanto riguarda pavimenti freddi e soffitti caldi. Il primo obiettivo di questa tesi è stato di realizzare un’analisi critica delle correlazioni disponibili in letteratura adatte ai sistemi radianti e di proporre delle equazioni per ogni configurazione di riscaldamento o raffrescamento da soffitto, pavimento o parete. In ambito residenziale il pavimento radiante rappresenta una delle soluzioni più richieste grazie all’elevato livello di comfort termico garantito; tuttavia, al fine di migliorare la qualità dell’aria e specialmente a causa della necessità di deumidificare l’aria in estate per evitare formazione di condensa, accanto al sistema radiante andrebbe installato un sistema di ventilazione meccanica. L’aria primaria in estate è solitamente a temperatura più bassa della temperatura della stanza e dotata di una certa velocità; nel caso di immissione da bocchette installate vicino ad una superficie radiante, lo scambio convettivo potrebbe venire variato rispetto ad una soluzione senza ventilazione. Mediante uno studio con simulazioni fluidodinamiche CFD è stato possibile valutare l’incremento dello scambio convettivo da un soffitto freddo mediante lo sfruttamento di aria primaria. I sistemi radianti, in particolare i sistemi a soffitto, rappresentano un’ottima soluzione per rimuovere i carichi termici degli uffici durante il periodo estivo, ma allo stesso tempo possono essere usati per il riscaldamento invernale degli stessi con buone prestazioni energetiche e di comfort termico. La differenza sostanziale è che durante la stagione invernale il sistema radiante si trova a lavorare prevalentemente in regime stazionario, mentre durante la stagione estiva i carichi esterni dovuti alla radiazione solare e all’escursione diurna, accompagnati da carichi interni dovuti all’occupazione umana, determinano condizioni piuttosto variabili durante la giornata. Il comportamento di sistemi radianti a regimi stazionari e transitori sono state studiate mediante prove in camera climatica; inoltre un modello di calcolo chiamato Digithon, sviluppato all’interno del Dipartimento di Fisica Tecnica dell’Università di Padova, è stato validato mediante un confronto con dati sperimentali. Seguendo un’opportuna procedura, riportata nella tesi, è stato possibile impostare dei profili di carico che simulano una tipica giornata estiva o invernale su una parete della stanza ed è stato studiato come il soffitto radiante reagisca per cercare di mantenere una certa temperatura di comfort nella stanza. Al fine di mantenere una buona qualità dell’aria, evitare la formazione di condensa, ma anche per incrementare la capacità di raffrescamento quando richiesto, i sistemi radianti per gli uffici andrebbero sempre associati a sistemi di ventilazione meccanica. Accanto ai tradizionali sistemi a soffitto con ventilazione a miscelazione, le soluzioni con ventilazione a dislocamento accoppiate a sistemi a pavimento o a soffitto sono alternative di crescente interesse per gli uffici. In edifici dove sia bassa la quantità di inquinanti emessi dai materiali edili, dai mobili e dalle attrezzature, la quantità di bioeffluenti dagli occupanti, dei quali l’anidride carbonica CO2 è normalmente usata come principale indicatore, è determinante per la qualità dell’aria interna. La capacità di rimozione dei contaminanti e, parallelamente, la capacità di immettere aria pulita negli ambienti sono espresse dall’efficienza di ventilazione (ventilation effectiveness). Mediante simulazione fluidodinamiche CFD è stato possibile confrontare l’efficienza di rimozione dei contaminanti utilizzando diverse soluzioni di ventilazione a dislocamento piuttosto che soluzioni tradizionali a miscelazione. La qualità di un ambiente interno andrebbe misurata in termini sia di comfort termico garantito all’occupante che di qualità dell’aria. Attraverso prove sperimentali in laboratorio, i principali indici di comfort termico e di efficienza di ventilazione sono stati determinati per diverse configurazioni di ventilazione a miscelazione e di ventilazione a dislocamento in ambienti rappresentativi di applicazioni residenziali o del terziario. I risultati sono stati in seguito utilizzati per effettuare una validazione di un modello fluidodinamico (CFD) creato per la previsione del movimento dell’aria in ambienti residenziali o uffici.

Nowadays individuals spend more than 85% of their total time in indoor environments, mainly at home and work. Thereby, the quality of the indoor environment plays a substantial role in human health and wellness. The four basic factors that define the perception of the indoor environment, through the senses, are the thermal comfort, the indoor air quality, the acoustical quality and the visual or lighting quality. A standard level of the above factors is ensured by the building envelope and the services systems. At the same time, the bearing structure provides the necessary resistance and durability to the construction in order to sustain the various loads without breaking down. Inevitably, over the years, all structures’ robustness declines and their functionality state degrades. For that reason, intensive provision should be given to assure the users’ safety and well-being. The objective of this study is to assess the current indoor air quality, the thermal comfort and the damages at four publicly owned buildings located in Athens, Greece. The evaluation was done through the facilities management contribution, a questionnaire survey and a technical visit – inspection where measurements were taken. Special focus was also put on the Sick Building Syndrome (SBS) and its effects. The results indicated that at 3 out of 4 buildings mainly suffer from unpleasant odors and lack of fresh air intake. Therefore, the installation of mechanical ventilation systems (air handling units, outdoor air processing units) combined with an effective air distribution system (confluent jet ventilation system) is suggested. Substantial building damages were detected at the cultural center (floorings, door/window openings, fungi) and specific proposals for restoration are made. Despite the existence of indicators of an unhealthy indoor environment, a direct correlation between the exposure to various pollutants and the SBS symptoms, cannot be established. The optimization of the research methodologies and the institution of new building design protocols is essential in order to overcome the SBS effects. On the whole, the questionnaire achieved to fulfil the objectives of the survey. It was comprehensible by the respondents while the outcome of the questionnaire and the inspection were consistent to each other. The questionnaire and the checklists are practical tools that could be used as a guide for future investigation in similar fields. Except for technical surveys and questionnaires, many suggestions for future maintenance of the buildings are provided aiming to retain their functionality. These proposals concern the services systems, the building envelope as well as the bearing structure of the buildings.

Lors d’un incendie en tunnel, la perte de visibilité due à la densité optique des fumées et leurs problèmes de toxicité sont considérés comme les risques principaux auxquels les usagers sont exposés. Pour cela, le contrôle de la fumée est souvent la partie la plus importante de la planification d’urgence. Les systèmes de ventilation sont l’une des principales mesures de protection à adopter pour empêcher la fumée de se répandre. Cependant, la propagation de la fumée est un phénomène très complexe et il est donc parfois difficile à contrôler. Cette complexité exige de meilleurs outils de sécurité pour améliorer l’efficacité des systèmes de ventilation et assurer ainsi la sécurité des personnes en cas d’incendie, ce qui constitue l’objectif principal de nos travaux de recherche. Dans cette thèse, l’étude des incendies dans les tunnels routiers équipés de systèmes de désenfumage longitudinaux et transversaux a été réalisée expérimentalement et numériquement. Les expériences ont été menées dans la maquette située au LMFA et les simulations numériques ont été réalisées en utilisant le code de calcul FDS (Fire Dynamics Simulator) avec l’approche de simulation des grandes échelles LES (Large Eddy Simulation). Le foyer est modélisé par le rejet d’un mélange d’air et d’hélium dans de d’air frais. Avec ce type de simulation d’incendie, les pertes de chaleur par rayonnement et par conduction à travers les parois du tunnel ne sont pas prises en compte, mais le modèle peut néanmoins fournir des informations sur la phénoménologie et les champs de données pouvant être comparés à des incendies réels. Dans une première partie, des mesures de champ de vitesse ont été effectuées à l’aide de la technique de vélocimétrie par images de particules PIV pour étudier la dynamique des rejets flottants dans des tunnels à ventilation longitudinale. L’objectif est d’évaluer les effets non Boussinesq (liés aux grandes différences de densité entre le rejet flottant et l’air ambiant) sur la dynamique des rejets "forcés" et "paresseux", dominés respectivement par le flux de quantité de mouvement et le flux de flottabilité. Ensuite, l'effet de barrières solides (connues sous le nom "d'écrans de cantonnement" et placées au plafond du tunnel) sur la propagation des fumées d’incendie dans des tunnels à ventilation longitudinale est étudié. Deux types d'obstacles ont été examinés: des "petites barrières", conçues pour être fixées le long du plafond du tunnel, et des "grandes barrières", conçues pour être mobiles et déployées uniquement en cas d’incendie. Pour ce dernier type, seulement une seule barrière est placée au plafond du tunnel. Les expériences ont été réalisées avec et sans les effets de blocage des véhicules, qui sont modélisés par des blocs cubiques de différentes tailles. Les résultats ont montré que les barrières peuvent contrôler efficacement la propagation des fumées, même à basses vitesses de ventilation. Le taux de réduction de la vitesse critique (définie comme la vitesse de ventilation minimale à partir de laquelle toutes les fumées sont repoussées en aval du feu, dans le même sens que le flux de ventilation) dépend du taux de blocage créé par les obstacles (barrières, blocs ou les deux) situés juste en amont de la source. Les pertes de charge induites par ces barriers ont été aussi évaluées. Les résultats finals ont montré que les grandes barrières sont plus efficaces que les petites barrières car elles réduisent considérablement la vitesse critique et induisent moins de perte de charge dans les tunnels encombrés. Dans une deuxième partie, à l'aide d'un système de ventilation transversale, les conditions de confinement des fumées entre deux trappes d’extraction situées de part et d'autre de la source sont étudiées. Les effets de la forme et de la position des trappes (y compris le cas particulier des trappes de pleine largeur) sur les performances du système de ventilation transversale ont été évalués. [...]
In this thesis, fires in road tunnels with longitudinal and transverse ventilation systems are investigated numerically and experimentally. The fire smoke is simulated as a buoyant plume obtained by injecting a mixture of air and helium into ambient air. With this simplified representation, the radiation and the heat losses at the walls are not taken into account, but the model can nevertheless provide relevant information on phenomenology and data fields that can be compared to real fires. The study aims to meet various objectives, in particular increasing the efficiency of the mechanical ventilation systems and improving the safety of tunnels users in the event of fires. In the first part, experiments are conducted to measure, using Particle Image Velocimetry (PIV) system, the velocity fields induced by turbulent buoyant plumes released within a longitudinally ventilated tunnel. The aim is to study the non-Boussinesq effects (i.e. effects related to large density differences between the buoyant plume and the ambient air) on the dynamics of the momentum-driven releases and buoyancy-driven releases. Then, the effect of solid barriers, placed at the tunnel ceiling, on the propagation of smoke in fire events within longitudinally ventilated tunnels is studied. Two types of barrier are considered: "small barriers" designed to be fixed in place and "large barriers" designed to be mobile in real tunnels. Experiments are carried out with and without vehicular blockage, which are modelled by blocks of different sizes and placed upstream of the source. It is found that the presence of barriers and/or blocks reduces the critical velocity, which is defined as the minimum ventilation velocity required to ensure that all the smoke remains downstream of the source, in the same direction as the ventilation flow. The reduction rate of the latter depends on the blocking rate created by the obstacles (barriers, blocks or both) located just upstream of the source. Subsequently, the effect of blockages on pressure losses inside the tunnel is investigated. It is shown that the large barriers are more effective than small ones because they reduce the critical velocity and induce less pressure losses in congested tunnels. In the second part, using a transverse ventilation system, the conditions of confinement of the smoke flow between two exhaust vents located on either side of a buoyant source are investigated. The effect of the shape and the position (with respect to the tunnel axis) of the dampers, including the specific case of full-width dampers, on the performance of the transverse ventilation system is evaluated. The extent of the backflow length beyond the extraction dampers, the confinement velocity and the stability of the smoke stratification are studied. Results show that the greater the proportion of the tunnel width the vent covers and the closer to the centre of the tunnel the vent is placed, the more efficient the ventilation system at confining the smoke to the extraction zone and ensuring the stability of the smoke stratification. The effect of solid barriers placed at the tunnel ceiling is also evaluated with transverse ventilation and it’s found that large barriers can improve the efficiency of vents that do not cover the full width of the tunnel, by reducing the confinement velocity and enhancing the stability of the smoke stratification. In the last part, numerical simulations of fires in a tunnel with longitudinal and transverse ventilation are carried out using Fire Dynamics Simulator (FDS) software and Large Eddy Simulation (LES) approach. Several physical simulations are numerically reproduced to complete the interpretation of the experimental results. A good agreement is usually reached between the experimental and the numerical results. [...]

The direct exposure to fire is not the most immediate threat to passengers&
#8217
life in case of fire in an underground transportation system. Most of the casualties in fire are the results of smoke-inhalation. Numerical simulation of fire and smoke propagation provides a useful tool when assessing the consequence and deciding the best evacuation strategy in case of a train fire inside the underground transportation system. In a station fire the emergency ventilation system must be capable of removing the heat, smoke and toxic products of combustion from the evacuation routes to ensure safe egress from the underground transportation system station to a safe location. In recent years Computational Fluid Dynamics has been used as a tool to evaluate the performance of emergency ventilation systems. In this thesis, Computational Fluid Dynamics technique is used to simulate a fire incidence in underground transportation systems station. Several case studies are performed in two different stations in order to determine the safest evacuation scenario in CFDesign 7.0. CFD simulations utilize three dimensional models of the station in order to achieve a more realistic representation of the flow physics within the complex geometry. The steady state and transient analyses are performed within a simulation of a train fire in the subway station. A fire is represented as a source of smoke and energy. In transient analyses, a fast t2 growth curve is used for the heat release rate and smoke release rate. The results of the studies are given as contour plots of temperature, velocity and smoke concentration distributions. One of the case studies is compared with a code well known in the discipline, the Fire Dynamics Simulator, specifically developed for fire simulation. In selection of the preferred direction of evacuation, fundamental principles taken into consideration are stated.

The aim of this project is to calculate how much energy could be saved in the School of Jädraås, in the municipality of Ockelbo. The objects of study were the lighting and the ventilation systems, not only because of the energy saving but due to the comfort also. After our study, the municipality wants to use our results to improve all their municipality buildings and save as much energy as it is possible in the whole municipality.

We analyzed the hours when the ventilation system is working during the whole year, and we calculated how much energy could be saved if the amount of working hours were decreased or if new devices, as heat exchangers, were installed.

In the lighting system part, the aim was not only the energy saving, but the comfort also. The currently lighting system is quite bad, specially in the dinning room, where bulbs are still lighting the room. These bulbs, anyways, should not be changed in the next ten years. The lighting system in the learning rooms is also old. Although there are fluorescent lamps already, some new lamps with lower energy consumption and better efficiency can be installed.

Dans le secteur de la santé et particulièrement en unité des soins intensifs, diverses situations cliniques sont rencontrées et l'interprétation d'une grande quantité de données, y compris celles fournies par les équipements tels que moniteurs et ventilateurs, est exigée pour une prise de décision appropriée. La disparité entre cette quantité importante d'information et la capacité humaine limitée crée une variabilité inutile à la décision clinique. Pour faire face au problème, les experts médicaux ont défini des stratégies en vue de promouvoir une pratique fondée sur les données probantes. Cette méthode est devenue un standard pour la pratique clinique et a montré beaucoup d'avantages en menant à la définition de directives spécifiques ou des protocoles précis à appliquer dans certaines situations. Cependant, l'utilisation de directives/protocoles, particulièrement dans les soins intensifs, exige une participation continue des professionnels au chevet du malade et est ainsi difficile à appliquer en pratique clinique. La définition d'assistants informatisés est une solution technologique intéressante à explorer pour faciliter l'introduction des protocoles dans la routine clinique. En ventilation mécanique, on assiste à une prise de conscience croissante sur le potentiel de l'informatisation et son applicabilité au-delà de la recherche et plus concrètement dans le soutien du clinicien dans sa prise de décision quotidienne. Ceci à travers la prise en charge des tâches répétitives et la proposition de suggestions. Ce domaine constitue un environnement idéal pour de telles applications surtout que les ventilateurs de réanimation son aujourd'hui des équipements électroniques sophistiqués qui peuvent embarquer des protocoles informatisés. L'objectif de cette thèse était d'explorer les aspects de développement, déploiement et d'efficacité des « contrôleurs intelligents » en ventilation mécanique afin d'accélérer leur création et leur adoption. Pour examiner les phases de développement et de déploiement, nous nous sommes concentrés sur l'utilisation et l'extension du SmartCare®, une plateforme logicielle qui facilite l'automatisation des procédures thérapeutiques en ventilation mécanique à partir de la modélisation des connaissances expertes jusqu'à leur exécution en temps réel dans un équipement médical. A travers une approche ascendante, en se basant particulièrement sur notre expérience pratique dans le design de contrôleurs intelligents et après l'examen de divers contrôleurs existants, l'objectif était de définir un catalogue de pièces maitresses pour la représentation des protocoles en ventilation mécanique. L'utilisation d'une ontologie du domaine assure une formalisation saine de ces pièces.Sur base de cette approche, nous avons développé un contrôleur pour l'oxygénation testé au chevet du malade. Nous rapportons ses performances comparées à la pratique standard
In healthcare, especially in critical care, various clinical situations are encountered and a huge amount of data, including those provided by equipment such as monitors and ventilators, are required for an appropriate decision-making. The mismatch between this vast amount of information and the human capability creates unnecessary variability in clinical decision. To cope with this problem, medical experts have defined specific strategy called evidence based medicine. This method has become the standard of practice and showed many benefits by leading to the definition of specific guidelines or precise protocols to follow in specific situations. However, the use of guidelines/protocols, especially in critical care, requires the continuous involvement of professionals at the patient's bedside strongly limiting their application in practice. The introduction of computerized assistants for implementing such guidelines/protocols may be an interesting technological solution. In mechanical ventilation where various protocols are available there is a growing acceptance that such computerization might be useful beyond research, in assisting clinicians in their daily decision making by taking over some routine tasks or providing suggestions. Moreover, this domain constitutes an ideal environment because mechanical ventilators are presently powerful electronic equipments in which computerized protocols can be efficiently embedded. The objective of this thesis was to explore several aspects of the development, deployment, and effectiveness of computerized protocols or smart controllers in mechanical ventilation in order to accelerate their creation and adoption. For this purpose, we focused on the use and the extension of SmartCare®, a computer framework for the automation of respiratory therapy starting from clinical knowledge modelling to execution in real time of specific routines embedded into medical products [1]. Through a reengineering approach, from practical experience in smart controller design and investigation of existing controllers, the objective was to define a catalogue of building blocks to facilitate the creation of new controllers. The modeling of such blocks using dedicated domain ontology ensures a sound formalization. To prove the effectiveness of such a generic approach, we built a smart controller for oxygenation tested on the patient's bedside. We reported its performance compared to standard therapy

The diploma thesis deals with the problems of the indoor environment of swimming pool halls. Firstly, it describes issues and principles of designing HVAC system in the areas with high humidity production. Thesis then focuses on various approaches to calculations of evaporation from the water surface and different possibilities of dehumidification including different types of HVAC units. This knowledge was applied to the design of HVAC system for particular assigned building, for which are proposed two different solutions. Thesis includes experimental part, its aim is to analyse one specific critical part of the hall. Based on local surveying and long-term measurements a few possibilities of improvement are suggested.

A ventilação mecânica pulmonar é a substituição da respiração espontânea de um paciente quando este não realiza ou realiza parcialmente esta tarefa. Esta ventilação é de extrema importância para o tratamento de pacientes em estado crítico em unidades de terapia intensiva e para a manutenção da oxigenação sanguínea durante cirurgias. A ventilação mecânica pulmonar consiste em empurrar os gases para dentro do pulmão de forma controlada, mantendo uma pressão inspiratória ou um volume inspiratório determinado. Além disso, controla o nível de pressão durante a expiração do paciente para manter os alvéolos abertos e dificultar lesões internas. Este trabalho se propõe a caracterizar uma especificação de engenharia para os sistemas de controle de ventilação, se baseando em características fisiológicas do sistema respiratório do paciente saudável e também com patologias conhecidas. São apresentados modelos matemáticos para os sistemas mecânicos responsáveis pela atuação na inspiração e na expiração do paciente, bem como um modelo matemático para o sistema respiratório. Foram desenvolvidos sistemas de controle, baseados no controlador PID, para os principais tipos de modalidades ventilatórias. Os sistemas controlados foram simulados e os resultados são apresentados neste trabalho. Os controles propostos foram implementados em equipamentos de anestesia e UTI projetados na K. Takaoka Ind. Com. Prod. Hosp. LTDA. entre 2008 e 2010 no Brasil, e estão sendo usados hoje nas salas de cirurgia e centros de terapia intensiva pelo Brasil e em alguns países da América do Sul e do Oriente médio.
The mechanical ventilation is the replacement of spontaneous breathing of a patient when it does not perform or partially perform this task. This ventilation is extremely important for the treatment of critically ill patients in intensive care units and for the maintenance of blood oxygenation during surgery. The mechanical ventilation consists in pushing the gas into the lungs in a controlled manner, maintaining a determined inspiratory pressure or inspiratory volume. In addition, it has to control the pressure level during the patients exhalation to keep the alveoli opened and prevent internal injuries. This work aims to characterize an engineering specification for the control systems of ventilation, relying on physiological characteristics of the patient\'s respiratory system on healthy subjects and also subjects with known diseases. Here are presented mathematical models for the mechanical systems responsible for acting on the inspiration and expiration of the patient, as well as a mathematical model for the respiratory system. There were developed control systems, based on the PID controller for the main types of ventilation modes. Controlled systems were simulated and the results are presented in this dissertation. The proposed controls were implemented in anesthesia and intensive care equipments designed in K. Takaoka Ind. Com Prod. Hosp. LTD. between 2008 and 2010 in Brazil, and are being used today in the operating rooms and intensive care centers in Brazil and some countries in South America and the Middle East.

Past research has shown that natural ventilation can be used to satisfy upwards of 98% of the yearly cooling demand when utilized in the appropriate climate zone. Yet widespread implementation of natural ventilation has been limited in practice. This delay in market adoption is mainly due to lack of effective and reliable control. Historically, control of natural ventilation was left to the occupant (i.e. they are responsible for opening and closing their windows) because occupants are more readily satisfied when given control of the indoor environment. This strategy has been shown to be effective during summer months, but can lead to both over and under ventilation, as well as the associated unnecessary energy waste during the winter months. This research presents the development and evaluation of a model-based control algorithm for natural ventilation. The proposed controller is designed to modulate the operable windows based on ambient temperature, wind speed, wind direction, solar radiation, indoor temperature and other building characteristics to ensure adequate ventilation and thermal comfort throughout the year without the use of mechanical ventilation and cooling systems. A midrise student dormitory building, located in Portland OR, has been used to demonstrate the performance of the proposed controller. Simulation results show that the model-based controller is able to reduce under-ventilated hours to 6.2% of the summer season (June - September) and 2.5% of the winter (October - May) while preventing over-heating during 99% of the year. In addition, the model-based-controller reduces the yearly energy cost by 33% when compared to a conventional heat pump system. As a proactive control, model-based control has been used in a wide range of building control applications. This research serves as proof-of-concept that it can be used to control operable windows to provide adequate ventilation year-round without significantly affecting thermal comfort. The resulting control algorithm significantly improves the reliability of natural ventilation design and could lead to a wider adoption of natural ventilation in appropriate climate zones.

Evidence-based medicine is at the heart of current medical practice where clinical decisions are driven by research data. However, most current therapy recommendations follow generalized protocols and guidelines that are based on epidemiological (population) studies and thus not suited for the individual patient's demands. Patient-tailored therapies are considered, hence, an unmet clinical need. We believe that mathematical models of the physiology can attend to such a clinical need, because they can be tuned to the individual patient. Such models provide a sound mathematical framework for personalized clinical decisions. In particular, physiological models in medicine can serve the following two purposes: 1) They can be an efficient tool to quantify cardiopulmonary dynamics, conduct virtual clinical/physiological experiments, and investigate the effects of specific treatments. 2) Model-based estimation techniques can assess physiological parameters or variables, which are otherwise impractical or dangerous to measure; they can effectively tune a generic model to become patient-specific, able to mimic the behavior of a particular patient. In this thesis, we propose a series of modifications to a previously developed cardiopulmonary model (CP Model) in order to better replicate heart-lung interaction phenomena that are typically observed under mechanical ventilation, hence allowing for a more accurate analysis of ventilation-induced changes in cardiac function. The response of this modified model is validated with experimental data collected during mechanical ventilation conditions. Further, as an industrial application of mathematical models, we present a patient emulator system that comprises the modified CP Model, a physical ventilator, and a piston-cylinder arrangement that serves as an electrical-to-hydraulic transducer. The modified CP Model then serves as the virtual patient that is being ventilated, where disease conditions can be instilled. Such a system is designed to offer a well-controlled experimental environment for ventilator manufacturers to efficaciously test and compare ventilation modalities and therapies, thereby enhancing their verification and validation manufacturing processes. Finally, we develop a model-based approach to estimate (noninvasively) the function of the cardiovascular system, in terms of cardiac performance (i.e., cardiac output) and the dynamics of the systemic arterial tree (i.e., time constant). With this technique, we envision to provide continuous and real-time bedside monitoring of changes in cardiovascular function, such as those induced by changes in ventilator settings.

This work takes us a step closer to realizing personalized medicine, complementing empirical and heuristic way in which clinicians typically work. This thesis presents mechanistic models of physiology. These models, given continuous signals from a patient, can be fine-tuned via parameter estimation methods so that the model's outputs match the patient's. We thus obtain a virtual patient mimicking the patient at hand. Therapeutic scenarios can then be applied and optimal diagnosis and therapy can thus be attained. As such, personalized medicine can then be achieved without resorting to costly genetics. In particular we have developed a novel comprehensive mathematical model of the cardiopulmonary system that includes cardiovascular circulation, respiratory mechanics, tissue and alveolar gas exchange, as well as short-term neural control. Validity of the model was proven by the excellent agreement with real patient data, under normo-physiological as well as hypercapnic and hypoxic conditions, taken from literature. As a concrete example, a submodel of the lung mechanics was fine-tuned using real patient data and personalized respiratory parameters (resistance, R_rs, and compliance, C_rs) were estimated continually. This allows us to compute the patient's effort (Work of Breathing), continuously and more importantly noninvasively. Finally, the use of Bayesian estimation techniques, which allow incorporation of population studies and prior information about model's parameters, was proposed in the contest of patient-specific physiological models. A Bayesian Maximum a Posteriori Probability (MAP) estimator was implemented and applied to a case-study of respiratory mechanics. Its superiority against the classical Least Squares method was proven in data-poor conditions using both simulated and real animal data. This thesis can serve as a platform for a plethora of applications for cardiopulmonary personalized medicine.

The suburbs of most Italian cities particularly feel this need of restoration. The immense quantity of public housing built from the '60s to the '80s, in response to a pressing need to create housing quickly and with limited financial resources, is now in urgent need of redevelopment both from the energy performance point of view and for increasing the poor internal comfort conditions. The research defines a sustainable refurbishment method for public residential buildings made with industrialized techniques in the Mediterranean climate, starting from the results obtained by the application of renovation strategies to some sample buildings built with these construction methods during the ‘60s-‘80s, located in the Florence area. Two building complexes are analysed: COMPLEX A located in Prato consisting of 2 buildings and COMPLEX B located in Firenze involving 4 buildings.

碩士
國立陽明大學
醫務管理研究所
101
Study Background: With an aging population, an increased incidence of chronic diseases and medical technology development, and an increase in medical expense is also observed when the number of patients under prolonged mechanical ventilation continues to rise. There is a rising concern for the appropriation of acute care hospital bed resources for patients under prolonged mechanical ventilation. In year 2000, the Bureau of National Health Insurance initiated a trial run of the “National Health Insurance Managed Care Demonstration Program for Ventilator Dependent Patients”, with a purpose of improving the appropriation of acute care hospital bed resources for patients under prolonged mechanical ventilation in clinical practice. It provides comprehensive medical service and improves the quality, as the medical resources are more appropriately shared in clinical practice. Objective: The study aimed to investigate the influence of integrated delivery system and tracheostomy on prognosis and medical resource usage in patients with prolonged mechanical ventilation, and to examine the independent effect of both interrentions. Method: In the study, a retrospective analysis was performed on the National Health Insurance database between year 2000 and 2009. Subjects included were patients under prolonged mechanical ventilation for more than 30 days, and descriptive statistics would analyze the basic characteristics of such patients. Inferential statistics included multiple regression analysis on length of stay, total inpatient expense, and the relation to ventilator dependent days. The Cox proportional hazard regression model was also used to analyze the mortality risk and the ventilator weaning rate. Result: The total samples in the study were 3522 patients, Patients under prolonged mechanical ventilation who received tracheostomy, showed longer length of stay, higher total hospital cost, and longer ventilator dependent days, decrease in mortality risk and ventilator weaning rate. The integrated delivery system reduced mortality and increased the chance of weaning but had a longer hospital and ventilator days with higher medical consumption. Patients who received both tracheostomy and integrated delivery system had longer survival. Conclusion: Both tracheostomy and integrated delivery system, decrease in mortality rate and increase in medical resource utilization. But patients in receiving integrated delivery system had a higher chance of ventilator weaning.

Human pregnancy is characterized by significant increases in central ventilatory drive and perceived respiratory discomfort (breathlessness). The physiological mechanisms of hyperventilation and breathlessness in pregnancy remain largely unknown and understudied. Objective: The main purpose of this research was to elucidate the mechanisms of maternal hyperventilation, and to systematically examine the contribution of alterations in central ventilatory drive, static/dynamic respiratory mechanics and their interaction with respect to the intensity of perceived breathlessness during exercise in pregnancy. General Methods: Experiments were conducted between 34-38 wks gestation and again 4-5 months post-partum in a total of 35 healthy, young women. A comprehensive mathematical model of ventilatory control was used to examine the role of alterations in wakefulness and central chemoreflex drives to breathe, acid-base balance and female sex hormones in maternal hyperventilation. The effects of pregnancy on detailed ventilatory (breathing pattern, airway function, operating lung volumes, esophageal pressure-derived indices of respiratory mechanics) and perceptual (breathing and leg discomfort) responses to incremental cycle exercise to the limits of tolerance were also examined. Results: Maternal hyperventilation resulted from a complex interaction between alterations in arterial and central acid-base balance and other factors that directly affect ventilation, including increased wakefulness and central chemoreflex drives to breathe, increased metabolism and decreased cerebral blood flow. Mechanical adaptations of the respiratory system, including recruitment of resting inspiratory capacity and reduced airway resistance, accommodated the increased demand for tidal volume expansion during exercise in pregnancy, while preserving effort-displacement and breathlessness-ventilation relationships. Variation in the severity of gestational breathlessness could not be explained by respiratory mechanical/muscular factors, but ultimately reflected variation in the amplitude of maternal hyperventilation and temporal desensitization to the sensory consequences of increased ventilation. Conclusion: Our results indicated that 1) the hyperventilation and attendant hypocapnia/alkalosis of pregnancy can be explained by alterations in wakefulness and central chemoreflex drives to breathe, acid-base balance, metabolic rate and cerebral blood flow; 2) mechanical adaptations of the respiratory system obviated the anticipated rise in perceived breathlessness for a given ventilation during exercise in pregnancy, and helped to ensure that peak aerobic working capacity was admirably preserved, even in late gestation; and 3) gestational breathlessness ultimately reflected the normal awareness of increased ventilation and contractile respiratory muscle effort.
Thesis (Ph.D, Kinesiology & Health Studies) -- Queen's University, 2008-08-28 16:01:40.78

碩士
輔仁大學
護理學系碩士班
93
This study aims at comparing of closed- and open-system endotracheal suctioning on the effects of artierial oxygenation and breathing effort during mechanical ventilation without pre-oxygenation. The independent variable is the endotracheal suctioning method and the dependent variables are the arterial blood oxygen pressure tested from the laboratory and the pressure-time product monitored by the pneumotachograph. The sample consisted 30 patients at the intensive care unit of a medical center in northern region of Taiwan. All the 30 cases were tested for the arterial blood oxygen pressure, only 22 of the 30 cases were tested for pressure-time product. A two groups cross-over experimental research design was applied, in which two patients were selected as a group and were randomly assigned one into Model 1, a closed-open sequencing of endotracheal suctioning system, and the other Model 2, an open-closed sequencing of endotracheal suctioning system. Thus, there were 15 patients in each model for test of arterial blood oxygen pressure and 11 patients for test of pressure-time product. Patients in model 1 were first applied a closed endotracheal suctioning system. Thereafter, these patients were received three measurement for arterial blood oxygen pressure at the time right before endotracheal suctioning, right after endotracheal suctioning and one minute after endotracheal suctioning, and were received six measurement for pressure-time product at the time right before endotracheal suctioning and once per minute for 5 minute after endotracheal suctioning. Thirty minutes after last data collected, patients' closed endotracheal suctioning system were transformed into open endotracheal suctioning system, and the same measures were repeated for tests of arterial blood oxygen pressure and pressure-time product. Patients in model 2, an open-closed sequencing of endotracheal suctioning system, the application of the endotracheal suctioning system was just reverse to model 1, but the measurement method for arterial blood oxygen pressure and pressure-time product was the same as of model 1. A better suctioning system should result in less decrease in the arterial blood oxygen pressure and less increase in the pressure-time product. There are two hypotheses in this study. Hypothesis 1 tests if the decrease on values of arterial blood oxygen pressure for pre-and post-endotracheal suctioning and to that of pre-endotracheal suctioning of the closed endotracheal suctioning system is less than that of the same comparison of the open endotracheal suction system. Result from the modified analysis of GEE model shows that the decrease of the arterial blood oxygen pressure between pre- and post-endotracheal suctioning on the closed endotracheal suctioning system is less than that of the open endotracheal suctioning system by 11.18 mmHg, but the difference does not reach the statistical significance level (p = .10). Hypothesis 2 tests if the increase on values of pressure-time product for pre- and post endotracheal suctioning of the closed endotracheal suctioning system is less than that of the same comparison of the open endotracheal suctioning system. Result from the modified analysis of GEE model shows that the increase of the pressure-time product between pre- and post-endotracheal suctioning on the closed endotracheal suctioning system is less than that of the open endotracheal suctioning system by 27.04 cmH2O．sec/breath, but the difference does not reach the statistical significance level (p = .39). It is suggested that a large sample size should be applied to retest these two hypotheses. Results of this study can be used as a reference to those who care for patients that are highly dependent on ventilators with high concentration of oxygen.

Please read the abstract in the section 00front of this document
Dissertation (MEng (Mechanical Engineering))--University of Pretoria, 2007.
Mechanical and Aeronautical Engineering
unrestricted

博士
國立臺灣科技大學
建築系
100
Radiant cooling ceiling systems have already been proven to potentially provide an improved thermal comfort environment. This work conducted a full-scale experiment in an office, and a computational fluid dynamics (CFD) simulation study for a radiant cooling ceiling system integrated with air dehumidification equipment installed in this test space. The obtained results from the experiment were compared with the values from the CFD simulation to validate the accuracy of the model. Predicted mean vote (PMV) index was used to assess the original indoor thermal condition and improved conditions according to the simulation results. Experimental variables included supply air temperature from the diffuser, surface temperature, and the area of the cooling panels. In addition, diffuser position in the mechanical ventilation system was analyzed that provided suggestions on improving the design of radiant cooling ceiling panels. This study proposed solutions alongside limitations on improving indoor thermal comfort and energy efficiency using a radiant cooling ceiling system in the subtropical regions of Taiwan.

Heating, ventilation and air conditioning systems (HVAC) are the single largest consumer of energy in commercial and residential sectors. Minimizing its energy consumption without compromising indoor air quality (IAQ) and thermal comfort would result in environmental and financial benefits. Currently, most buildings still utilize constant air volume (CAV) systems with on/off control to meet the thermal loads. Such systems, without any consideration of occupancy, may ventilate a zone excessively and result in energy waste. Previous studies showed that CO₂-based demand-controlled ventilation (DCV) methods are the most widely used strategies to determine the optimal level of supply air volume. However, conventional CO₂ mass balanced models do not yield an optimal estimation accuracy. In this study, feed-forward neural network algorithm (FFNN) was proposed to estimate the zone occupancy using CO₂ concentrations, observed occupancy data and the zone schedule. The occupancy prediction result was then utilized to optimize supply fan operation of the air handling unit (AHU) associated with the zone. IAQ and thermal comfort standards were also taken into consideration as the active constraints of this optimization. As for the validation, the experiment was carried out in an auditorium located on a university campus. The results revealed that utilizing neural network occupancy estimation model can reduce the daily ventilation energy by 74.2% when compared to the current on/off control.

Dissertação de mestrado integrado em Engenharia Civil
As exigências da sociedade moderna e os seus hábitos estão a transformar o planeta Terra, desgastando os seus recursos naturais e poluindo os solos, a água e a atmosfera. O elevado ritmo de consumo energético, especialmente no sector da construção, tem levado a um intenso estudo de desenvolvimento e à utilização de energias renováveis com o objetivo de reduzi-lo até um nível sustentável. As Diretivas Comunitárias e a legislação portuguesa atualmente em vigor apontam para o aumento da eficiência energética dos edifícios, conseguindo-o através do aumento do isolamento térmico da envolvente, do melhoramento da estanquicidade ao ar dos envidraçados e da implementação de um mínimo horário de renovações do ar interior. No entanto, tem-se verificado que se com o aumento do isolamento da envolvente se conseguem reduzir os fluxos de calor entre o exterior e o interior, com a renovação de ar por hora aumenta-se as necessidades de aquecimento e por vezes de arrefecimento. Neste contexto, a utilização conjunta de sistemas de ventilação convencionais e de permutadores de calor com tubos enterrados no solo, pode trazer benefícios na redução dos consumos energéticos das necessidades de aquecimento e arrefecimento. Nestes sistemas, o ar insuflado é pré-aquecido ou pré-arrefecido ao circular nos tubos, dependendo da temperatura do ar em relação ao solo. Estas diferenças de temperatura podem atingir valores durante os picos de calor ou de frio, suficientes para reduzir significativamente ou eliminar a necessidade de equipamentos de aquecimento e arrefecimento. Tendo em conta que o referido sistema já foi alvo de variados estudos e é amplamente utilizado em vários países, pretende-se com este estudo a comparação direta entre os comportamentos térmicos de um edifício com e sem um sistema de tubos enterrados. Em adição, pretende-se estudar parametricamente a influência que os parâmetros de comprimento, diâmetro, profundidade e tipo de material dos tubos exercem na performance do sistema. Para isso, utilizar-se-á o programa de simulação energética “EnergyPlus” de modo a avaliar o desempenho da manutenção do conforto térmico num ambiente doméstico em várias zonas de Portugal.
The demands of modern society and its habits are changing the planet Earth, wearing out natural resources and polluting the soil, water and atmosphere. The high rate of energy consumption, especially in the construction sector, has led to an intense study, development and use of renewable energy in order to reduce it to a sustainable level. The Community Policies and Portuguese legislation currently in effect lead to an improvement of buildings' energy efficiency, achieving it by increasing thermal insulation of the external envelope, improving the air tightness of the glazing and the implementation of a minimum legal value of interior air changes per hour. However, it has been found that if with increased thickness of the surrounding insulation the heat flow between the inside and the outside is reduced, the imposed air changes per hour increase the energy consumption for heating and cooling. In this context, the joint use of conventional HVAC and earth-to-air heat exchanger systems can bring benefits in reducing energy consumption for heating and cooling. In these systems, the insufflated air is preheated or precooled, depending on the difference between the soil and air temperatures, when it flows through the buried pipes. These temperature difference can reach values, at the peaks of heat or cool, enough to significantly reduce or eliminate the need for heating and cooling equipment. Considering that this system has been the subject of various studies and is widely used in various countries, the aim of this study is the direct comparison of the thermal behaviour of a building with and without the buried pipes' system. In addition, it is intended to perform a parametrical study which determines the system's performance influence of parameters such as length, diameter, depth and pipes' material. For this, the energy simulation program "EnergyPlus" shall be used, in order to evaluate the thermal performance of the earth-to-air heat exchanger system applied in a residential environment in several places of Portugal.