Rozprawy doktorskie: „Ventilation”

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Ramsay, Michelle Clare. "Patient-ventilator interaction in domiciliary non-invasive ventilation". Thesis, King's College London (University of London), 2018. https://kclpure.kcl.ac.uk/portal/en/theses/patientventilator-interaction-in-domiciliary-noninvasive-ventilation(9b60bd3e-84b6-4605-96a8-22b4546b1e90).html.

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Introduction: Patient-ventilator asynchrony (PVA) can adversely affect the initiation of home mechanical ventilation (HMV). The aim was to quantify the prevalence of PVA during HMV and determine the relationships between PVA and adherence to therapy, respiratory muscle loading, nocturnal gas exchange, health-related quality of life measures and sleep quality. Method: A pilot randomised control trial was conducted to compare a physiological led set-up of HMV, using neural respiratory drive to optimise ventilator set-up, to an expert led set-up. Type and frequency of PVA were measured by surface parasternal muscle electromyography, thoraco-abdominal plethysmography and mask pressure during initiation of HMV and 3 months post therapy. Severe PVA was defined as affecting ≥10% of breaths. Results: 40 patients (25 male) were enrolled with an age of 58±17years and a body mass index(BMI) of 33±10kg/m2. Underlying diagnoses were neuromuscular ± chest wall disease (NMD-CWD,n=11), obesity-related chronic respiratory failure (ORRF,n=13) and chronic obstructive pulmonary disease (COPD, n=16). Overall, PVA affected 25.6(16.4-35.7)% breaths at initiation of HMV, with ineffective efforts as the predominant type of PVA affecting 10.9(4.6-23.7)% breaths. No difference was observed in the frequency of PVA between physician led and physiological led set-up of HMV at initiation or 3 months(28.4(17.4-37.6)%vs 25.6(14.0-30.4)%;p=0.6 and 22.4(13.3-37.1)%vs23.3(15.2-41.5)%;p=0.7,respectively). No correlations were observed between PVA and ventilator adherence(rs=0.02,p=0.90), nocturnal oxygen saturations(rs =0.04,p=0.85), nocturnal carbon dioxide levels(rs=0.15,p=0.41), respiratory muscle unloading(rs=0.06,p= 0.76), patient perception of ventilator synchronisation(rs=0.03,p=0.9) at 3 months of HMV therapy. 10 patients (7 male) underwent polysomnography assessment of sleep quality. No further correlations were observed between PVA during sleep and sleep efficiency (rs=-0.6,p=0.1), wake after sleep onset(rs=0.5,p= 0.2) or total sleep time(rs=-0.4,p= 0.3) at 3 months of HMV therapy. Conclusion: Severe PVA was identified in the majority of patients irrespective of pathophysiological disease. This was not associated with inappropriate delivery of effective ventilation. These data suggest that elimination of PVA may not be required to successfully set-up HMV.

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Sperber, Jesper. "Protective Mechanical Ventilation in Inflammatory and Ventilator-Associated Pneumonia Models". Doctoral thesis, Uppsala universitet, Infektionssjukdomar, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-282602.

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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.

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Carteaux, Guillaume. "Optimisation des interactions patient-ventilateur en ventilation assistée : intérêt des nouveaux algorithmes de ventilation". Thesis, Paris Est, 2015. http://www.theses.fr/2015PESC0027/document.

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En ventilation assistée, les interactions patient-ventilateur, qui sont associés au pronostic, dépendent pour partie des algorithmes de ventilation. Objectifs : Caractériser l'intérêt potentiel des nouveaux algorithmes de ventilation dans l'optimisation des interactions patient-ventilateur : 1) en ventilation invasive, deux modes et leurs algorithmes nous ont semblé novateurs et nous avons cherché à personnaliser l'assistance du ventilateur en fonction de l'effort respiratoire du patient au cours de ces modes proportionnels : ventilation assistée proportionnelle (PAV+) et ventilation assistée neurale (NAVA) ; 2) en ventilation non-invasive (VNI) nous avons évalué si les algorithmes VNI des ventilateurs de réanimation et des ventilateurs dédiés à la VNI diminuaient l'incidence des asynchronies patient-ventilateur. Méthodes : 1) En PAV+ nous avons décrit un moyen de recalculer le pic de pression musculaire réalisée par le patient à chaque inspiration à partir du gain réglé et de la pression des voies aériennes monitorée par le respirateur. Nous avons alors évalué la faisabilité clinique d'ajuster l'assistance en ciblant un intervalle jugé normal de pression musculaire. 2) Nous avons comparé une titration de l'assistance en NAVA et en aide inspiratoire (AI) en se basant sur les indices d'effort respiratoire. 3 et 4) En VNI, nous avons évalué l'incidence des asynchronies patient-ventilateur avec et sans l'utilisation d'algorithmes VNI : sur banc d'essai au cours de conditions expérimentales reproduisant la présence de fuites autour de l'interface ; en clinique chez des patients de réanimation. Résultats : En PAV+, ajuster le gain dans le but de cibler un effort respiratoire normal était faisable, simple et souvent suffisant pour ventiler les patients depuis le sevrage de la ventilation mécanique jusqu'à l'extubation. En NAVA, l'analyse des indices d'effort respiratoire a permis de préciser les bornes d'utilisation et de comparer les interactions patient-ventilateur avec l'AI dans des intervalles d'assistance semblables. En VNI, nos données pointaient l'hétérogénéité des algorithmes VNI sur les ventilateurs de réanimation et retrouvaient une meilleure synchronisation patient-ventilateur avec l'utilisation de ventilateurs dédiés à la VNI pour des qualités de pressurisation par ailleurs identiques. Conclusions : En ventilation invasive, personnaliser l'assistance des modes proportionnels optimise les interactions patient-ventilateur et il est possible de cibler une zone d'effort respiratoire normale en PAV+. En VNI, les ventilateurs dédiés améliorent la synchronisation patient-ventilateur plus encore que les algorithmes VNI sur les ventilateurs de réanimation, dont l'efficacité varie grandement selon le ventilateur considéré
During assisted mechanical ventilation, patient-ventilator interactions, which are associated with outcome, partly depend on ventilation algorithms.Objectives: : 1) during invasive mechanical ventilation, two modes offered real innovations and we wanted to assess whether the assistance could be customized depending on the patient's respiratory effort during proportional ventilatory modes: proportional assist ventilation with load-adjustable gain factors (PAV+) and neurally adjusted ventilator assist (NAVA); 2) during noninvasive ventilation (NIV): to assess whether NIV algorithms implemented on ICU and dedicated NIV ventilators decrease the incidence of patient-ventilator asynchrony.Methods: 1) In PAV+ we described a way to calculate the muscle pressure value from the values of both the gain adjusted by the clinician and the airway pressure. We then assessed the clinical feasibility of adjusting the gain with the goal of maintaining the muscle pressure within a normal range. 2) We compared titration of assistance between neurally adjusted ventilator assist (NAVA) and pressure support ventilation (PSV) based on respiratory effort indices. During NIV, we assessed the incidence of patient-ventilator asynchrony with and without the use of NIV algorithms: 1) using a bench model; 2) and in the clinical settings.Results: During PAV+, adjusting the gain with the goal of targeting a normal range of respiratory effort was feasible, simple, and most often sufficient to ventilate patients from the onset of partial ventilatory support until extubation. During NAVA, the analysis of respiratory effort indices allowed us to precise the boundaries within which the NAVA level should be adjusted and to compare patient-ventilator interactions with PSV within similar ranges of assistance. During NIV, our data stressed the heterogeneity of NIV algorithms implemented on ICU ventilators. We therefore reported that dedicated NIV ventilators allowed better patient-ventilator synchronization than ICU ventilators, even with their NIV algorithms engaged.Conclusions: During invasive mechanical ventilation, customizing the assistance during proportional ventilatory modes with the goal of targeting a normal range of respiratory effort optimizes patient-ventilator interactions and is feasible with PAV+. During NIV, dedicated NIV ventilators allow better patient-ventilator synchrony than ICU ventilators, even with their NIV algorithm engaged. ICU ventilators' NIV algorithms efficiency is however highly variable among ventilators

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Fjellborg, Anders. "Energieffektiv ventilation". Thesis, Linköpings universitet, Energisystem, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-76910.

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Syftet med detta examensarbete är att konkretisera och visa på de grundläggande problemen med inomhusklimatet i Brogårdsfabriken i Vetlanda, för att utifrån detta komma fram med åtgärdsförslag för att minska dem. Detta samt att utreda möjligheterna att ta till vara den i fabriken internt genererade överskottsvärmen och minska energianvändningen. Arbetet har skett i ett top-down-perspektiv, vilket betyder att fabriken ses som ett slutet system där tillförd energi in i systemet ställs mot bortförd energi ut ur systemet. Stor del av arbetet har bedrivits i simuleringsprogrammet IDA – Indoor Climate and Energy till vilket data samlats in genom fysiska mätningar i fabriken och genom intern dokumentation på företaget. Problemen med inomhusklimatet för de anställda ute i produktionen är av olika karaktär i olika delar av fabriken och varierar även i intensitet beroende på vilken tid på året som studeras. Dock är de bakomliggande orsakerna till problemen alltid desamma. Det handlar bland annat om bristfällig processventilation, stora öppna lokaler som är svårkontrollerade, problem med infiltration genom portar och andra öppningar i klimatskalet. Förslag att återskapa en tidigare befintlig vägg rekommenderas för att lösa problemet med kalldrag i packhallen. Väggen skulle förhindra luftrörelser i områden där problemen upplevs och nästintill eliminera dem. Fokus på att minska energianvändningen har skett genom att titta på en optimering av ventilationsdriften vilket har resulterat i en kostnadsbesparing på cirka 370 tkr/år vid reducering av driften under enbart helger. Det finns ytterligare potential till kostnadsbesparingar för ventilationsdriften under andra tillfälliga driftstopp eller semesterstängningar av fabriken, om ventilationsdriften anpassas efter detta.

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Bengtsson, Patrik, i Joel Blomfelt. "Variabel Ventilation". Thesis, KTH, Energiteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-190163.

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A lot of people today spend most of their lives indoors. Both at home and at work time is spent in areas where the climate is not governed by the weather but by ventilation systems meant to create a suitable indoor climate. Despite having such a central part in society the subject of ventilation seldom gets very much attention, and in the current situation it is not a foregone conclusion that indoor air quality and climate is satisfactory. Those who build the homes and premises normally explain this as a result of cost considerations, but essentially the situation originates from other issues. A more accurate explanation is that there are some problems concerning the planning stage of ventilation systems, which implies both a highly simplified designing approach and the price, not the function and quality, being decisive. The problems have been confirmed by several sources and research is in progress within the area in order to address the underlying issues. Among other things, various types of test-bed housing is constructed in several parts of the world, designed for measurement and data collection in a real living environment. Such projects can both verify different system´s function and promote the development of new innovations, but also help in creating well-justified research material regarding, among other things, different ventilation solutions such as for example variable ventilation. One of these projects, called KTH Live-in Lab, is located at KTH in Stockholm. This report presents a work regarding comparisons of different ventilation solutions for such a student apartment as constructed in the ongoing research project KTH Live-in Lab. The work focuses on both finding a suitable system and then link the results to an adequate combination for use with variable ventilation. In order to deal with today´s problems within the area, the work is focused on deviating from the current conventional approach and ventilation design. The result is illustrated digitally in the form of computer simulations of air flow in a virtual model of the apartment, and comparisons led both to a number of conclusions, and proposals of suitable and unconventional solutions. For non-variable ventilation systems, a suitable system consisted of one ventilation inlet placed at ceiling level and two outlets whereof one at ceiling level and one at floor level. For variable ventilation, the results showed that the system solution should suitably be combined with the ability to switch to an inlet at floor level at nights and other scenarios without activity and movement in the apartment. Other conclusions are mainly about findings regarding how certain design variations affect the characteristics of the ventilation system.
Många människor spenderar idag större delen av sitt liv inomhus. Det är vanligt att man både hemma och på jobbet vistas i utrymmen där klimatet inte styrs av väder och vind utan av ventilationssystem som är tänkta att skapa ett lämpligt inomhusklimat. Trots ventilationens centrala del av samhället hamnar ämnet dock ofta i skymundan, och i dagens läge är det ingen självklarhet att inomhusklimaten och dess luftkvalité är tillfredställande. Av dem som bygger bostäderna och lokalerna förklaras detta ofta bero på kostnadsaspekter, men i grund och botten är det annat som ligger till grund för dagens situation. En bättre förklaring är att det finns viss problematik kring ventilationens planeringsskede, vilket innebär ett väldigt förenklat arbetssätt och att kostnad prioriteras framför funktion och kvalité. Problemen har bekräftats från flera håll och forskning pågår inom området i syfte att möta de bakomliggande orsakerna. Bland annat uppförs på flera håll i världen olika typer av testbädd-bostäder utformade för mätning och datainsamling i en verklig boendemiljö. Med hjälp av dessa kan man både verifiera olika systems funktion och gynna framtagning av nya innovationer och välgrundat forskningsmaterial gällande bland annat olika ventilationslösningar som exempelvis variabel ventilation. Ett av dessa projekt, med namnet KTH Live-in Lab, utförs på KTH i Stockholm. I denna rapport presenteras ett arbete gällande jämförelser av olika ventilationslösningar för en sådan studentlägenhet som uppförs i det pågående bygg- och forskningsprojektet KTH Live-in Lab. Arbetet fokuseras på att dels hitta en lämplig ventilationslösning och sedan även koppla resultatet till en möjlig kombination att använda för variabel ventilation. I syfte att möta dagens problematik fokuserades på att frångå dagens konventionella arbetssätt och ventilationsdesign. Resultatet illustreras digitalt i form av datorsimuleringar av luftflöden i en virtuell modell av bostaden, och jämförelserna ledde till ett antal slutsatser och förslag på lämpliga okonventionella lösningar. För icke-variabel ventilation var det lämpligt att placera ett inlopp i taknivå, samt två utlopp varav ett i taknivå och ett i golvnivå. För variabel ventilation visade det sig att denna systemlösning bör kombineras med möjlighet att växla inloppet till lågt inlopp på nätter och andra scenarion utan aktivitet och rörelse i bostaden. Övriga slutsatser gäller vilka egenskaper som bör varieras beroende på vad man vill uppnå med ventilationen.

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Hammash, Muna Hassan. "CARDIAC RHYTHM DURING MECHANICAL VENTILATION AND WEANING FROM VENTILATION". UKnowledge, 2010. http://uknowledge.uky.edu/gradschool_diss/56.

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The transition from mechanical ventilation (MV) to spontaneous ventilation during weaning is associated with hemodynamic alterations and autonomic nervous system (ANS) alterations (reflected by heart rate variability [HRV]). Although cardiac dysrhythmias are an important manifestation of hemodynamic alterations, development of dysrhythmias during MV and weaning and subsequent impact on length of MV has received little attention. The purposes of this dissertation were to 1) evaluate the relationship of heart rate variability (HRV) during weaning to the development of cardiac dysrhythmias and 2) determine the relationship of cardiac dysrhythmias to length of MV. A convenience sample of 35 patients (66.7% men; mean age 53.3 years) who required MV was enrolled in this study. Continuous 3-lead electrocardiographic data were collected for 24 hours at baseline during MV and for the first 2 hours during the initial weaning trial. HRV was evaluated using spectral power analysis. Twenty- seven patients out of 30 were exposed to a combination of pressure support (8-15 cm H2O) and continuous positive airway pressure 5 cm H2O during weaning trial. Three patients self- extubated and received supplemental oxygen through either a partial rebreathing or non-rebreathing mask. Low frequency (LF) power HRV decreased, while high frequency (HF) and very low frequency (VLF) power HRV did not change during weaning. Multiple regression analyses showed that LF and HF HRV were significant predictors of occurrence of ventricular and supraventricular ectopic beats during weaning, while VLF power predicted occurrence of ventricular ectopic beats only. The mean of occurrence of supraventricular ectopic beats per hour during weaning was double the mean at baseline, while the mean of ventricular ectopic beats per hour did not change. Mean number of supraventricular ectopic beats per hour during weaning was a significant predictor of length of MV. This dissertation has fulfilled an important gap in the evidence base for cardiac dysrhythmias during weaning from MV. Cardiac dysrhythmias and HRV alterations should be systemically evaluated during MV and weaning trials in order to decrease length of MV.

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Jerräng, Carlstedt Ludwig. "A comparison between emergency ventilation systems semi-transvers ventilation and natural ventilation in Road Tunnel A". Thesis, Luleå tekniska universitet, Byggkonstruktion och brand, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-65671.

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Rashid, Dewan Md Harunur Mechanical &amp Manufacturing Engineering Faculty of Engineering UNSW. "Wake survey behind a rotating ventilator". Awarded by:University of New South Wales. School of Mechanical and Manufacturing Engineering, 2002. http://handle.unsw.edu.au/1959.4/19076.

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With environmental concern growing in both affluent and developing countries, roof top ventilators, a form of natural ventilation requiring only wind energy to ensure quality air circulation and comfort is becoming a considered choice of many households and industries. Unfortunately, however, many of these ventilators have evolved through trial and error and the flow physics associated with these ventilators is barely understood. The present experimental project was, therefore, undertaken as part of UNSW- Industry collaboration program funded under an Australian Research Council Grant to explore whether the aerodynamics forces acting on these ventilators during their operation could be obtained. A commercial roof top ventilator supplied by industry was, therefore, tested in an open jet wind tunnel of the University of New South Wales and the results are presented in this thesis. A novel feature of this project is the examination of the suitability of ???the three dimensional wake traverse??? technique to the wake of rotating ventilator. This technique has so far been applied with limited success to the wake of lifting bodies of fixed wing configuration only. In the absence of adequate data in the literature on rotating ventilator, the aerodynamics force components obtained by this technique have been compared against force balance measurements. The results show that the wake traverse technique is capable of determining lift and total drag forces associated with the ventilator flow during its operation from the pressure and velocity information gathered downstream of a ventilator in its wake. Generally, from these data, the technique also allows isolation of the profile and induced components of the drag force. However, from the induced drag value, while it is possible to determine the lift force, it is however, found that a more accurate value of lift force can be evaluated using axial vorticity formulation. The availability of the above technique which does not require measurements on the test specimen itself, will aid in providing a cost efficient investigation of the aerodynamic forces and consequently the performance of a roof top ventilator.

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Todd, Susan Katharine. "Shock assisted ventilation". Thesis, University of Surrey, 1999. http://epubs.surrey.ac.uk/843314/.

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Respiratory distress syndrome is the major cause of mortality in premature babies. Increasing numbers of neonates are now surviving the disease due to advances in techniques used in neonatal intensive care units. Mechanical ventilation is an essential part of the treatment for respiratory distress syndrome and is an area in which improvements and modifications are constantly being made. In the early 1980's a new infant ventilator was introduced involving ventilation by a distal jet. As yet, the mechanisms by which the distal jet ventilator enhances gas exchange are unknown. Original experiments are carried out to record the attenuation and speeds of the pressure wave produced by the distal jet ventilator. The observed changes in wave shape and the high wave speed imply that the ventilator produces waves operating within an acoustic regime. An understanding of the gas exchange mechanisms active in shock assisted ventilation is initiated by a comprehensive investigation of the transport properties of acoustic waves. The advection and diffusion that result from a linear concentration gradient in an acoustic flow are analysed, from the Eulerian and Lagrangian viewpoints. The Eulerian investigation shows that the total flux of tracer through a given pipe can be optimized by choosing the frequency appropriately. The Lagrangian transport is increased as both frequency and radius increase. For all values of parameters, Lagrangian streaming is observed, with a steady net flow in the pipe core away from the tube entrance and an opposing net flow near the tube walls.

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CHAIPRASIT, KRIRKPHAN. "Designing for Ventilation". The University of Arizona, 1989. http://hdl.handle.net/10150/555319.

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Bergman, Eric, i Emma Gahne. "Ventilation av inomhusskjutbanor". Thesis, KTH, Byggteknik och design, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-257747.

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Skytte med eldhandvapen skapar buller, utsläpp av farliga ämnen och risk för att avlossade projektiler missar sina mål och istället hamnar utanför skjutbanan. Att förlägga skjutbanor inomhus löser vissa av dessa problem. Samtidigt kan risken för att utsättas för farliga ämnen öka för dem som brukar skjutbanan. En nyckelfaktor för att omhänderta dessa farliga ämnen och därmed skapa en god arbetsmiljö på inomhusskjutbanan är att ventilationen fungerar på rätt sätt. Syftet med detta arbete är främst att utvärdera hur ventilationen på inomhusskjutbanor bör utformas för att ventilera bort de hälsofarliga ämnen som uppstår. Arbetet har särskilt fokuserat på blyföroreningar men resultatet är generaliserbart även för många andra föroreningar som är aktuella. Arbetet är en del av Fortifikationsverkets pågående projekt om framtidens inomhusskjutbanor. Gränssättande för ventilationen är att arbetsmiljön på en inomhusskjutbana måste uppfylla relevanta arbetsmiljökrav. Utöver frågan om ventilation belyses även andra aspekter som är av vikt för att säkra en god arbetsmiljö. Arbetet har baserats på en forskningsöversikt där material från 1975 och fram till idag har studerats. Sökningarna har skett både strukturerat och riktat. Den strukturerade sökningen har skett i Web of Science och Scopus. Arbetet har identifierat de normer som används internationellt och som också har legat till grund för många av de skjutbanor som uppförts i Sverige. Vidare har arbetet identifierat den ursprungliga rapport som merparten av den tillgängliga litteraturen baserats på. I denna ursprungliga rapport har vi även identifierat viktiga frågetecken angående vilka grundförutsättningar som denna rapport baserats på. Resultatet av forskningsöversikten är att skjutbanor bör projekteras med laminärt flöde (“kolvströmning”) från skyttarna och mot kulfånget. Ventilationen bör projekteras med ett flöde på mellan 0,25 och 0,4 m/s. Ett bra verktyg under projekteringen är CFD-simuleringar. Med dessa kan olika tekniska lösningar utvärderas och för befintliga skjutbanor kan även orsak till eventuella problem undersökas. CFD-simuleringsresultaten bör i görligaste mån verifieras mot uppmätta värden. Vidare är både städning och personlig hygien viktiga faktorer för att arbetsmiljön på en inomhusskjutbana skall vara god. Ytskikt som är lätta att städa skall väljas och förutsättningar för att hantera både tvätt av arbetskläder och personlig hygien skall finnas. Dessa resultat knyts ihop under diskussionskapitlet där två grundläggande scenarier formuleras, ett för en nybyggnation och ett för en ombyggnad av en befintlig inomhusskjutbana.
The use of firearms creates noise pollution, release of toxic elements and a risk that the projectiles miss the targets and end up outside of the firing range. One of the solutions to these issues is to erect walls and a roof around the range, and thus create an indoor firing range. This might however increase the range users’ exposure to toxic elements related to the discharge of firearms. To mitigate this the indoor firing range needs a properly designed and well-functioning ventilation system. The purpose of this study is to evaluate how ventilation systems for indoor firing ranges should be designed in order to remove the toxic elements released when shooting. The study is primarily focused on lead pollution, but the results can also be generalised for a multitude of other relevant pollutants. The study is part of the Swedish Fortifications Agency (Fortifikationsverket) project regarding the design of future indoor firing ranges. The design parameters for ventilation systems at indoor firing ranges are regulated by the occupational safety and health regulations. In the final part of the study the authors also address other important aspects to create a safe working environment at indoor firing ranges. This study is conducted as a research review where literature from 1975 up until today has been studied. Search terms based on permutations of “shooting”, “firing”, “range”, “ventilation” and “firearm” have been used in the Web of Science and Scopus databases. The resulting list, after being culled for duplicates and “false positives”, contained approximately 70 articles. Reviewing these articles let us identify the design parameters used both internationally and nationally in Sweden. We also identified the original report that most of the internationally available literature is based upon. In this Bachelor of Science thesis, we also raise some questions related to the original report and the prerequisites it was based upon. The result of the research survey is that the ventilation for indoor firing ranges should be designed for laminar flow (piston flow) in the direction from the shooters towards the bullet trap. The air flow should be between 0,25 and 0,4 m/s (50 to 75 feet per minute). A good tool when designing the range ventilation is CFD simulations. CFD simulations allow for early phase evaluation of different design solutions. Similar simulations can also be used when problem solving problems on already existing ranges, if any. Furthermore, both cleaning and personal hygiene are crucial components to achieve a safe working environment at indoor firing ranges. To facilitate cleaning the range should have surface materials that are non-porous and easy to clean. Washing facilities for work clothes and personal hygiene should be present. These results are addressed as part of the discussion chapter in the Bachelor of Science thesis where two basic scenarios are formulated, one for building a new indoor firing range, and one for redesigning an existing indoor firing range.

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Benscoter, Dan T. "Ventilation Reconciliation: Improving the Accuracy of Documented Home Ventilator Settings in a Pediatric Home Ventilator Clinic". University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin155421301584871.

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Pálsson, Daði Snær. "Hybrid Ventilation : Simulation of Natural Airflow in a Hybrid Ventilation System". Thesis, KTH, Installations- och energisystem, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-146761.

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This thesis investigates the possibilities of using hybrid ventilation in an office building in Stockholm. The focus is on simulating the natural airflow to find out for which conditions it is sufficient. The thesis is done at White Arkitekter AB in cooperation and under the supervision of environmental specialists working there. A literature study is carried out to study what has been done before in Sweden as well as in other countries. Computer simulations are used to simulate the airflow to examine the conditions and architecture. A synthetic computer model representing a realistic office building is built up as a starting point. The ventilation method for the natural ventilation part is to take air in through the fa\c{c}ade and use the stack effects in an atrium for natural ventilation. By altering the architecture and the sizes of the openings according to the results from the simulations the building is dimensioned and formed to cope with the rules and requirements about the indoor air quality in workplaces. The simulations are done with a multi zone energy performance simulation tool that can simulate airflows and indoor air climate conditions in the zones as well as the energy consumption. Computational fluid dynamics calculations are then used to more closely simulate the conditions within the zones. The results from those simulations suggest that the natural ventilation as a part of a hybrid ventilation works for all the floors of the building for up to 10$\,^{\circ}\mathrm{C}$. The computational fluid dynamics simulations showed that the thermal comfort of all the occupants is fulfilled for these conditions but there is a risk of occupants experiencing draught because of to high velocities in the air especially for the colder outdoor temperatures. For the higher outdoor temperatures the airflow needs to be enforced to ensure sufficient conditions for the occupants and for the colder temperatures mechanical ventilation is needed to decrease heat losses and avoid the risk of draught.

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Lofaso, Frédéric. "Effet de la ventilation mécanique sur le contrôle de la ventilation". Paris 12, 1996. http://www.theses.fr/1996PA120064.

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Jusqu'a ces dernieres annees les modifications de l'activite respiratoire au cours de la ventilation mecanique avaient ete peu explorees chez l'homme. Nous avons donc etudie les mecanismes physiologiques qui expliquent une diminution de l'activite inspiratoire et une modification de l'activite expiratoire sous ventilation mecanique. En effectuant une augmentation progressive du co#2 inspire sous ventilation mecanique, nous avons pu mettre en evidence l'existence d'une inhibition extra-humorale (non liee a la capnie) de l'activite inspiratoire. En montrant qu'au cours de la ventilation mecanique, l'inhibition extra-humorale de l'activite inspiratoire est moins presente chez les transplantes bipulmonaires que chez les sujets normaux, nous avons pu evoquer l'importance du role des recepteurs bronchiques a l'etirement dans la genese de cette inhibition extra-humorale. Nous avons observe que l'importance de l'inhibition de l'activite inspiratoire depend de l'importance du debit inspiratoire initial insuffle par le ventilateur. Ainsi, l'activite inspiratoire peut etre reduite a une valeur proche de zero et la compliance thoracopulmonaire peut etre mesuree chez des sujets eveilles. Nous avons egalement pu mettre en evidence l'apparition d'une activite expiratoire sous certains modes d'assistance ventilatoire, responsable de l'apparition d'une pression expiratoire positive intrinseque. Ainsi, nous avons observe qu'une ventilation en pression positive continue peut induire, du fait de l'augmentation de volume pulmonaire, une activite expiratoire remplacant l'activite inspiratoire ; et que cette activite expiratoire disparait si l'augmentation de volume pulmonaire est prevenue par une contrepression thoraco-abdominale

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Nöjd, Mathilda, i Emma Petersson. "Parallelltak med mekanisk ventilation : En jämförelse mellan mekanisk och naturlig ventilation". Thesis, Uppsala universitet, Institutionen för samhällsbyggnad och industriell teknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-415713.

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To build and conserve the moisture proof roof constructions is a central problem in the building industry. Outdoor ventilated roof constructions is considered to be a riskful construction that can be burdened with moist damages. It is problematic to build parallel roof with low energy consumption that are resistant to moist. New demands of energy efficient buildings has contributed to an increased amount of insulation in roof constructions. Well insulated roof constructions in combinations with moist and cold winters is the main cause to the current moisture problematic in Sweden. High relative humidity in air gap and high moisture in materials increases the risk for mold growth. The winter is a critical period of time due to outside air containing high amount of moisture that can be harmful for roof constructions that are ventilated by outside air. Organic materials like wood is sustained a risk for mold growth by a relative humidity of 75%. Duration and a favorable temperature are also required for mold growth to take place. Parallel roofing usually consists of wood materials that can be attacked by mold at favorable conditions. Tongue and groove and battens have a position close to the outer layers in a parallel roofing that contributes to them being exposed to mold growth that should be especially consider. There is a large need for technical solutions to be able to handle the current moist problems in Swedish constructions. Mechanical ventilation is one of the technical solutions that is controlled by sensors that regulates the ventilations in roof constructions air gap. The mechanical ventilation is controlled by sensors and fans. Sensors measure and compares the current temperature and vapour content of the outside air and the air in the air gap. At appropriate conditions the ventilation activates and at inappropriate conditions the ventilation is limited. This report is focused on comparing outdoor ventilated parallel roofing to mechanical ventilated parallel roofing. This report studies an existing building outside Norrtälje with parallel roofing. This system is equipped with sensors that logs the temperatures, relative humidity and moisture on the tongue and groove and battens in the air gaps in both the part of the roof that is mechanically ventilated and outdoor ventilated. The collected data have been analyzed in a risk analysis and a mold analysis. The risk analysis compares data from 2 or more measuring points to be able to analyze the difference in result. The mold analysis consists of a simulation in the program: WUFI Bio and delivers an index of calculated mold growth per year. This study indicates that roof constructions with outdoor ventilation runs a big risk of mold growth during the winter season. The mechanically ventilated roof construction shows a trend that reduces the risk of mold growth in all orientations and in the ridge. The measuring points with southern orientations shows a trend that, of a mechanically ventilated roof, will reduces mold growth in a higher degree compared to the other orientations. Even though the reduced effect of mold growth in mechanically ventilated roof constructions the results indicates a result where mold growths on tongue and groove and battens. Although the risk is not as extensive as in naturally ventilated roofs.
Att bygga och bibehålla fuktsäkra takkonstruktioner är ett centralt problem inom byggbranschen. Utomhusventilerade takkonstruktioner anses vara en riskkonstruktion som kan drabbas av fuktskador. Det är problematiskt att bygga parallelltak med låg energiförbrukning som är beständigt mot fukt. Nya krav på energieffektiviseringar har bidragit till ökade mängder isolering i takkonstruktioner. Välisolerade takkonstruktioner i kombination med fuktiga och kalla vintrar är den huvudsakliga orsaken till den rådande fuktproblematiken som finns i Sverige. Hög relativ fuktighet i luftspalten och hög fuktkvot i materialet ökar risken för mikrobiell påväxt. Vinterhalvåret är en kritisk period eftersom utomhusluften innehåller hög mängd fukt som kan vara skadlig för takkonstruktioner som utomhusventileras. Organiska material som trävirke löper risk för mikrobiell påväxt vid en relativ fuktighet på 75 %. Det krävs även varaktighet och en gynnsam temperatur för att mikrobiell påväxt ska kunna uppstå. Parallelltak består vanligtvis av trämaterial som kan angripas av mögel vid gynnsamma förutsättningar. Råspont och läkt har en position långt ut i parallelltaket som bidrar till att de löper stor risk för mögelpåväxt och bör särskilt beaktas. Det finns stort behov av tekniska lösningar för att kunna lösa den rådande fuktproblematiken i svenska bostäder. Mekanisk ventilation är en teknisk lösning som styr och reglerar ventilationen i takkonstruktionens luftspalt. Den mekaniska ventilationen styrs av sensorer och fläktar. Sensorerna jämför temperatur och ånghalt i utomhusklimatet med klimatet i luftspalten. Vid goda klimatförhållanden tillåts ventilation i luftspalten och vid sämre förhållanden begränsas ventilationen. Syftet med den mekaniska ventilationen är att parallelltaket endast ventileras när det leder till uttorkning. Rapporten har fokus på att jämföra utomhusventilerat parallelltak (naturlig ventilation) med mekanisk ventilation. Rapporten studerar en befintlig byggnad med parallelltak belägen utanför Norrtälje. Parallelltaket är utrustat med loggrar som mäter relativ fuktighet, temperatur och fuktkvot i råspont eller läkt i luftspalter med naturlig och mekanisk ventilation. Mätdata har analyserats i en riskanalys och en mögelanalys. Riskanalysen jämför mätdata från två eller flera mätpunkter för att kunna analysera skillnader i resultatet. Mögelanalysen består av simuleringar i programmet WUFI Bio och anger ett fiktivt mögelindex för beräknad påväxt i millimeter per år. Studien indikerar att luftspalter med naturlig ventilation löper stor risk för mögelpåväxt under vinterhalvåret. Den mekaniska ventilationen uppvisar en trend som reducerar risken för mögelpåväxt i samtliga väderstreck, inklusive taknock. Mätpunkter med mekaniska ventilation orienterad mot söder och väster uppvisar en trend som procentuellt reducerar mögelpåväxten i högre grad jämfört med resterande väderstreck. Trots den reducerande effekten med mekanisk ventilation indikerar resultatet att det finns risk för mögelpåväxt även på råspont och läkt i luftspalter med mekanisk ventilation. Däremot är risken inte lika omfattande.

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Walsh, Brian Kendall. "Computer-aided mechanical ventilation". Thesis, Rush University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10111109.

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Statement of the problem: The systematic implementation of evidence-based practice through the use of guidelines, checklists and protocols has been shown to mitigate the risks associated with MV, yet variation in practice remains prevalent. Recent advances in MV, physiologic monitoring, device-to-device communication, computer processing and software engineering have allowed for the development of an automated point-of-care access to real-time goal setting and practice variance identification. Our aim was to assess the utility of a computer-aided MV (CAMV) system that displays variances and scores the overall MV course. Methods: A retrospective categorization of the ventilation and oxygenation statuses of patients within our pediatric intensive care unit (PICU) over a 2 '/z years period utilizing 15 rule-based algorithms was initiated as a proof of concept. Goals were predetermined based on generally accepted values. All patient categories were calculated and presented as a percent of recording time. Following the feasibility study, a retrospective observational study (baseline), followed by two sequential interventions made over a 2-month period was conducted. Phase I comprised a survey of goals of MV by clinicians caring for patients being monitored by the CAMV system. Phase II intervention was the setting and monitoring of goals of MV with a web browser based data visualization system (T3). An outcome measurement tool was developed to score each MV course. The MV score (MVS) evaluated four outcomes: (1) acceptable ventilation, (2) acceptable oxygenation, (3) barotrauma free and (4) volutrauma-free states as a percent of recording time. Results: Pilot consisted of 222 patients. The Baseline phase evaluated 130 patients, Phase I enrolled 31 patients and Phase II enrolled 36 patients. There were no differences in demographic characteristics between cohorts. One hundred and seventy-one surveys were completed in Phase I. An increase in the use of T3 by 87% was observed in Phase II from Phase I. MVS improved by 8.4% in Phase I and 11.3% in Phase II from Baseline. The largest improvement was in the volutraumafree category. MVS was 9% higher on average in those who survived. Conclusion: The use of CAMV was associated with an improvement in MVS. Further research is needed to determine if improvements in MVS through a targeted, process-oriented intervention such as CAMV will lead to improved patient outcomes.

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Patel, Deena. "Optimisation of neonatal ventilation". Thesis, King's College London (University of London), 2014. https://kclpure.kcl.ac.uk/portal/en/theses/optimisation-of-neonatal-ventilation(020793ce-af66-48de-b969-bc0d702a673f).html.

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Background: Infants born prematurely or at term may unfortunately suffer morbidity from ventilator related complications. New ventilation techniques have been developed aimed at reducing that morbidity, but have yet to be fully evaluated. Aim: To optimise the delivery of new techniques using physiological outcome measures. Methods: A series of studies were undertaken. The objectives were: • In prematurely born infants with acute respiratory distress, to determine the optimal level of volume targeted ventilation. • In term and prematurely born infants, to assess the effect on work of breathing of the addition of pressure support (PSV) to synchronised intermittent mandatory ventilation (SIMV) during weaning and then compare the efficacy of PSV to assist control (ACV) in a randomised trial. • To perform in vitro and in vivo assessments of proportional assist ventilation (PAV). • The physiological outcome measures were the transdiaphragmatic pressure time product (PTPdi), respiratory muscle strength, thoracoabdominal asynchrony, tension time index of the diaphragm and assessment of asynchronous events. Results: A volume target of 4ml/kg in comparison to 6ml/kg or no volume targeting resulted in a higher PTPdi (p <0.001). In infants weaning from the ventilator, the PTPdi was 20% lower (p <0.001) during SIMV with PSV in comparison to SIMV alone. No significant difference in the duration of weaning was demonstrated between PSV and ACV. The in vitro PAV study highlighted abnormalities of airway pressure waveform and higher than excepted airway pressures during both elastic and resistive unloading. Conclusions: Low levels of volume targeting even within the ‘physiological’ range significantly increased the work of breathing. A triggered mode supporting all the infant breaths was superior to when a limited number of breaths were supported. When similar inflation times were used, triggered modes supporting all breaths were equally efficacious. Unloading levels affect the efficacy of PAV; these may be determined by using the ventilator calculated respiratory mechanics.

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Shetty, Sandeep Krishnanand. "Optimisation of neonatal ventilation". Thesis, King's College London (University of London), 2018. https://kclpure.kcl.ac.uk/portal/en/theses/optimisation-of-neonatal-ventilation(4bf50e9a-9ef5-41f9-baff-db581cf231d2).html.

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Background: Survival of neonates requiring respiratory support has improved over the last two decades, but unfortunately many suffer morbidity from ventilator related complications. Aim: To undertake a series of studies using physiological measurements as outcomes in infants with evolving or established bronchopulmonary dysplasia (BPD) to test the following hypotheses and carry out a national survey. Hypotheses: Proportional assist ventilation (PAV) compared to assist control ventilation (ACV) would improve oxygenation as assessed by the oxygenation index (OI). Neurally adjusted ventilatory assist (NAVA) compared to ACV would improve oxygenation. Use of heated, humidified, high flow nasal cannula (HHFNC) would not have increased given the results of recent randomised trials. Continuous positive airway pressure (CPAP) would reduce the work of breathing (WOB) and thoraco-abdominal asynchrony (TAA) and improve oxygen saturation (SaO2) compared to HHFNC. Methods: Four studies were undertaken. The OI was calculated from measurement of blood gases and the level of respiratory support. A survey was undertaken of lead practitioners in all UK neonatal units. The WOB was assessed by measurement of the pressure time product of the diaphragm (PTPdi) and TAA using respiratory inductance plethysmography (RIP).

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Howe, Kimberly Palazzo. "Mechanical Ventilation Antioxidant Trial". Case Western Reserve University School of Graduate Studies / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=case1112877564.

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Chowdhury, Olie. "Optimisation of neonatal ventilation". Thesis, King's College London (University of London), 2015. http://kclpure.kcl.ac.uk/portal/en/theses/optimisation-of-neonatal-ventilation(eac22c4d-b74f-4e29-8a7f-995a5c17c8a9).html.

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Background: Survival of neonates requiring intensive care has improved, but many suffer ventilator-related complications. This thesis aims to optimise use of ventilation techniques, with a focus on infants born at term. Hypotheses: In infants with acute respiratory failure, volume-targeted ventilation (VTV) will be superior to pressure-limited ventilation (PLV). Proportional assist ventilation (PAV) will be effective in reducing elastic and resistive work of breathing (WOB) in an in vitro experiment. Methods: A series of studies were undertaken. National survey of practice in relation to respiratory support in term infants. Comparison of WOB at different levels of volume-targeting in term infants. Randomised comparison of VTV and PLV in preterm infants. Analysis of spontaneous respiratory activity in ventilated term infants. In vitro study of effect of elastic and resistive unloading on WOB during PAV. Results: Respiratory support practices for term-born infants differed between different levels of care. In term infants, WOB was higher at 4ml/kg compared to 5 and 6ml/kg. In preterm infants, there was no difference in time to achieve weaning criteria on VTV versus PLV. Fewer infants on VTV experienced hypocarbia. Patterns of patient-ventilator interaction were described for term-born infants. Active expiration was more common on SIMV versus CMV, and less common on triggered ventilation at 4ml/kg compared to 6ml/kg or no volume-targeting. Using PAV, elastic unloading was more effective than resistive unloading in reducing WOB.

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Mallya, Prashant Moodabidri. "Pressure support ventilation or synchronised intermittent mandatory ventilation for weaning premature babies on mechanical ventilation : a multi centre randomised controlled trial". Thesis, University of Newcastle upon Tyne, 2017. http://hdl.handle.net/10443/3820.

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Mechanical ventilation is life saving as a respiratory support for preterm infants with respiratory distress syndrome. There is good evidence now that any form of volume-targeted modality of mechanical ventilation is superior over pressure-targeted modality to reduce chronic lung disease and death. It is perceived by minimising the duration of mechanical ventilation would reduce the exposure to positive pressure breaths and thereby could reduce long term morbidities such as chronic lung disease. An area of lacunae is defining what is weaning on mechanical ventilation. Whilst most clinicians will agree when to commence mechanical ventilation there is paucity of consensus on when to commence weaning on mechanical ventilation and the best way for weaning to prevent extubation failure. Pressure support ventilation (PSV) is pressure-targeted modality of ventilation designed to support spontaneous breathing. It was designed as a weaning mode to facilitate extubation. Pure PSV has no back up rate. Currently, PSV is used in combination with other modes such as SIMV to provide some back up respiratory rate for the unreliable respiratory drive due to apnoea in preterm infants. However, there is inadequate understanding of the appropriate PSV level for weaning preterm infants on mechanical ventilation. Clinicians routinely use 50%-70% of peak inflation pressures used prior to commencing the weaning mode. Use of Pressure support ventilation (PSV) could be variable- with one extreme utilising minimal pressure to just overcome the tube resistance (PSmin) with the aim to prevent fatigue and avoid extubation failure. The other extreme is augmenting spontaneous breathing effort to provide a full tidal volume breath (PSmax). Features of flow triggering and flow cycling aid synchrony at inspiration and expiration and this allows greater autonomy to the infant to control all aspects of its breathing cycle. Addition of some PSV to aid spontaneous breaths has shown to reduce the duration of weaning. A randomised controlled study was designed to compare duration of weaning using PSmax and SIMV. Infants less than 32 weeks gestation at birth with respiratory distress syndrome from surfactant deficiency were eligible to participate. 93 infants stratified in three groups based on their gestation at birth were randomised over 30-month period. Weaning was commenced in the randomised mode when infants reached a set priori of MAP < 10 cm H2O, FiO2 < 40% and had a reliable respiratory drive for at least 2 consecutive hours. In the control arm (SIMV with PSmin)– clinicians reduced the back up rate to wean. In the intervention arm (PSmax with ten SIMV breaths)- clinicians reduced the PSVmax to PSVmin for weaning. A minute ventilation test was performed to assess readiness to extubation when both arms reached PSmin with ten back up SIMV breaths. Primary outcome for the study was duration of weaning on mechanical ventilation. Our study suggests there is no difference between the two groups but there is a trend towards faster extubation in the PSV arm (the median time to extubate in the SIMV arm was 42 (95%CI, 28.23 to 55.76) hours and the median time to achieve the primary outcome in the PSV arm was 31 (95% CI, 12.59 to 49.40) hours). The survival distribution between the interventions was statistically not significant, Chi-square 0.768, p 0.381. This effect was more evident in bigger infants weighing at least 1500 grams. There was no difference in the secondary outcomes between the two groups and common preterm morbidities were equally balanced. There were no adverse events during the study period to report. Contrary to the general belief, infants are not disadvantaged by weaning on PSVmax. Clinical outcomes were comparable with the traditional SIMV method of weaning on mechanical ventilation.

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Balaji, Ravishankar. "Breathing Entrainment and Mechanical Ventilation in Rats". Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1307743446.

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Tomasi, Roberta. "Energy performance, comfort and ventilation effectiveness of radiant systems coupled with mechanical ventilation". Doctoral thesis, Università degli studi di Padova, 2012. http://hdl.handle.net/11577/3422467.

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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.

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Thille, Arnaud. "Asynchronies patient-ventilateur au cours de la ventilation assistée". Phd thesis, Université Paris-Est, 2010. http://tel.archives-ouvertes.fr/tel-00667286.

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Des asynchronies patient-ventilateur sont fréquemment observées en ventilation assistée. Objectif : Déterminer l'incidence et les facteurs favorisants des asynchronies, venant du patient, du ventilateur ou des réglages, et préciser le réglage optimal du ventilateur. Méthodes : Nous avons évalué l'incidence des asynchronies avec une méthode simple et non invasive basée sur l'analyse des courbes du ventilateur. Chez les patients qui présentaient des efforts inefficaces, nous avons mesuré l'effort inspiratoire avec une sonde œsophagienne afin d'optimiser le réglage du ventilateur. Nous avons évalué l'impact du mode ventilatoire sur la qualité du sommeil avec une polysomnographie complète. Enfin, tous les ventilateurs de réanimation ont été testés sur banc afin de comparer les performances en termes de trigger et pressurisation. Résultats : Près d'un quart des patients présentaient des asynchronies fréquentes. La durée de ventilation de ces patients était plus longue et le sevrage plus difficile. Les efforts inefficaces, qui représentaient les asynchronies les plus fréquentes, étaient favorisés par une assistance ventilatoire excessive. La réduction du niveau d'aide inspiratoire (AI) permettait d'éliminer quasi-complètement les efforts inefficaces, sans augmenter l'effort inspiratoire et sans modifier la vraie fréquence respiratoire du patient. Le mode ventilatoire n'avait pas d'influence sur la qualité du sommeil et les asynchronies. Les efforts inefficaces survenaient aussi bien en AI qu'en ventilation assistée contrôlée. Avec un niveau d'AI adéquat, les apnées centrales étaient peu nombreuses et n'avaient pas d'influence sur la qualité du sommeil. Les performances insuffisantes observées avec certains ventilateurs peuvent également altérer la synchronisation. Conclusion : Les asynchronies patient-ventilateur sont fréquentes et associées à une durée de ventilation prolongée. Une " dose de ventilation " excessive favorise les efforts inefficaces, mais un réglage optimal du ventilateur permet de minimiser ces asynchronies. Cette thèse est un support pour déterminer dans une étude plus large si une synchronisation adéquate peut réduire la durée de ventilation.

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Clark, Craig. "Use of hybrid ventilation techniques for improved energy efficiency of fan systems". Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33962.

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The goal of this thesis was to improve the energy efficiency of building ventilation systems by exploring new methods of applying natural ventilation concepts. Strictly natural systems have limitations in which climates they can function or can provide optimal performance; these limitations lead to the use of mechanical or hybrid ventilation. This study looked at methods of combining the operation of the systems, such that the natural components improve the efficiency of the mechanical system.

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Hermand, Eric. "Contrôle ventilatoire à l'exercice et en hypoxie : mise en évidence d'une périodicité constitutionnelle". Thesis, Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCD037/document.

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L’instabilité de la ventilation est un phénomène connu chez l’homme. Elle était jusqu’à présent observée chez l’homme sain en altitude et chez les patients souffrant d’insuffisance cardiaque (IC) et de syndrome d’apnées du sommeil (SAS), d’origine centrale, obstructive ou mixte, le plus souvent pendant le sommeil. Une analyse spectrale rétrospective de tests d’effort en hypoxie a mis à jour une instabilité ventilatoire lorsque le système de contrôle de la ventilation est soumis à une double contrainte, physiologique (exercice modéré) et environnemental (hypoxie simulant une altitude de 2000 à 4800 m d’altitude). Des protocoles prospectifs ont corrélé positivement l’amplitude de ces oscillations de la ventilation au débit cardiaque (Q̇c) et au niveau de ventilation (V̇E), tandis que la période est raccourcie lorsque V̇E et Q̇c augmentent. À l’opposé d’une période des apnées d’environ 1 minute chez les patients IC et SAS, nos observations ont permis de mesurer la période des oscillations ventilatoires à l’exercice et en hypoxie entre 11 et 12 secondes. Les sujets montrant une plus forte réponse ventilatoire à l’hypoxie et une sensibilité plus élevée au CO₂ exhibent une plus grande instabilité ventilatoire. L’hyperoxie et l’hypercapnie ont des effets opposés : alors que l’inhalation d’O₂ ne modifie pas la stabilité du système (vs normoxie), l’hypercapnie hyperoxique exacerbe le phénomène oscillatoire. Un traitement pharmacologique par acétazolamide (ACZ) améliore la stabilité ventilatoire, appuyant ainsi, en regard des données précédentes, le rôle central des chémorécepteurs périphériques dans la survenue des oscillations de la ventilation. Un modèle mathématique du contrôle de la ventilation intégrant, parmi de nombreux paramètres cardiorespiratoires, les sensibilités à l’O₂ et au CO₂, et les interactions périphérique-central, confirme l’implication du niveau d’hypoxie et du délai de convection sanguine entre les poumons et les chémorécepteurs périphériques dans la période des oscillations. Il souligne également le rôle potentiel de l’espace mort dans la survenue de l’instabilité respiratoire
Breathing instability is a well-known phenomenon in human. Until now, it was observed in healthy subjects at altitude et in patients suffering from chronic heart failure (CHF) or sleep apnea syndrome (SAS), central, obstructive or mixed, mostly during sleep. A retrospective spectral analysis of standard hypoxic exercise test evidenced a ventilatory instability when the control system is submitted to a double stress, physiological (moderate exercise) and environmental (hypoxia, from 2000 to 4800m simulated altitudes). Prospective analyses positively correlated magnitude of the ventilatory oscillations to cardiac output (Q̇c) and ventilation (V̇E), whereas their period is shortened with increasing V̇E and Q̇c. Unlike the one-minute period apneas in CHF and SAS patients, we observed a much shorter period at exercise in hypoxia, between 11 and 12 seconds. Subjects with a higher ventilatory response to hypoxia and a greater sensitivity to CO₂ showed a deeper breathing instability. Hyperoxia and hypercapnia have opposite effects : O₂ inhalation does not alter the system stability, hypercapnia enhances the oscillatory phenomenon. A pharmacological treatment by acetazolamide (ACZ) improves breathing stability, supporting a major role of peripheral chemoreceptors in the genesis of ventilatory oscillations. A mathematical model of ventilation control including, among numerous cardiorespiratory parameters, sensibilities to O₂ and CO₂, peripheral-central interactions, confirms the contribution of hypoxia level and the delay of blood convection between lungs and peripheral chemoreceptors in the oscillations period. It also highlights a potential role of dead space in the onset of breathing instability

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27

Booth, Derrick W. "An evaluation of industrial ventilation troubleshooting methods /". Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/10105.

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Chowdhury, Patrik. "Aspekter som avgör anestesisjuksköterskans val av peroperativ ventilation vid bukkirurgi, volym eller tryckkontrollerad ventilation?" Thesis, University of Gävle, Ämnesavdelningen för vårdvetenskap, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-4864.

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Bakgrund. Enligt den nya kompetensbeskrivningen för anestesisjuksköterskor framgår bland annat att anestesisjuksköterskan ska ha kompetens att övervaka och följa upp ventilation och cirkulation hos sina patienter. Det har länge varit vanligt att använda volymkontrollerad ventilation (VCV) till patienter som genomgår bukkirurgi. Nu finns det ett annat alternativ, tryckkontrollerad ventilation (PCV). Det är ett omdiskuterat ämne huruvida det mer traditionella VCV eller det senare PCV ska tillämpas på patienter som genomgår bukkirurgi. Syfte. Syftet med denna studie var att beskriva de aspekter som avgör anestesisjuksköterskans val av ventilationsmode vid bukkirurgi. Metod. Studien har en deskriptiv design med en kvalitativ ansats. Tio anestesisjuksköterskor fick svara på en frågeguide. Frågeguiden var konstruerad med öppna frågor. Svaren analyserades utifrån ett innehållsanalytiskt perspektiv. Resultat. Svaren på frågeguiden redovisas utifrån följande subkategorier: patientens bakgrund, operationsberoende aspekter, operationens förlopp, patient instabilitet, utbildning samt patientsäkerhet. Diskussion. Det visade sig att det fanns aspekter som påverkade anestesisjuksköterskan inför valet av ventilationsmode så som: patientens ålder, tidigare sjukdomar, operationsteknik samt kunskap om anestesiapparaten.

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Sütterlin, Robert. "Jet Ventilation for Airway Surgery : The Influence of Mode and Frequency on Ventilation Efficacy". Doctoral thesis, Uppsala universitet, Anestesiologi och intensivvård, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-229033.

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In surgery for airway obstruction, the anesthetist and the ear-nose-throat surgeon share the approach to the airway and jet ventilation (JV) is a mutually convenient ventilation technique for both parties. As a consequence of the open system jet ventilation is applied in, bedside measurements of lung volumes are cumbersome to perform and thus, there is a lack of studies comparing different modes of JV or investigating the influence of ventilator settings on lung volumes and gas exchange. In this thesis, single frequency jet ventilation and superimposed high frequency jet ventilation (SHFJV) at different frequencies are systematically compared with respect to lung volume changes, underlying airway pressure variations and the resulting gas exchange. We compared three single-frequency JV modalities with SHFJV in patients. Moreover, we performed a systematic investigation of single frequency JV and SHFJV in a porcine model. Single frequency JV and SHFJV were compared frequency-wise in intact airways and in a newly developed model of tracheal obstruction. This model was also used to assess the influence of variable airway diameter on ventilation effectiveness during SHFJV. We measured chest wall volume variations with opto-electronic plethysmography and obtained airway pressures as well as gas exchange parameters. In unobstructed airways, both single-frequency JV and SHFJV provided adequate oxygenation, despite differences in lung volumes. Carbon dioxide removal was most effective using single frequency JV at a frequency of 150 min-1. During SHFJV, for both intact and obstructed airways, the choice of frequency for the high frequency component had little influence on lung volumes, airway pressures and gas exchange. With decreasing airway diameter and SHFJV, we observed air trapping and lower tidal volumes and acceptable oxygenation. Carbon dioxide removal, however, was insufficient at the narrowest airway diameter. In single frequency JV, very high frequencies resulted in negligible tidal volume and inacceptable gas exchange. Airway obstruction potentiated this frequency dependence. In conclusion, in intact airways, single frequency JV at sufficiently low frequencies provided adequate oxygenation and better CO2 removal than SHFJV. With decreasing airway diameter, SHFJV provided better oxygenation and CO2 removal and may therefore be the mode of choice in more complicated cases.

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Ronski, Stephanie. "Ventilation der Grönlandsee : Variabilität und ihre Ursachen 1994-2001 = Ventilation on the Greenland Sea /". Bremerhaven : Alfred-Wegener-Institut für Polar- und Meeresforschung, 2003. http://www.gbv.de/dms/bs/toc/364268026.pdf.

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Choonya, Gasper. "Experimental investigation of ventilation performance of corner placed stratum ventilation in an office environment". Thesis, Högskolan i Gävle, Energisystem och byggnadsteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-29710.

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Energy use in buildings account for about one third of the total global energy supply and contributes as much as 30% of the anthropogenic greenhouse gas emissions. It is estimated that energy use in buildings will increase to 67% by 2030. The need for better thermal comfort and air quality in indoor environments is the leading cause for high energy use in buildings. Heating, ventilation and air conditioning systems take up about 50% of the total energy use in buildings which is about 10-20% of the national energy use in most developed countries. The development and adoption of sustainable ventilation systems is a viable solution to mitigate climate change and curtail carbon emissions. The experimental study was conducted in a room resembling a modern office in a laboratory environment. The study involved investigating the ability of the system to provide cooling and heating. Concentration decay tracer gas technique using Sulphur hexafluoride (SF6) gas was used to determine the local air change index and air change efficiency in the room. Low-velocity omni-directional thermistor anemometer type CTA88 were used to measure the air velocity and temperature in the room. Smoke was used to visualise the flow patterns created in the room. The climate chamber was used to mimic climatic conditions in winter. Fifteen cases were investigated with five air flow rates set points (30, 40, 50, 60 and 70 l/s) at three supply air temperatures, i.e., 17.6 °C, 21.0 °C and 25.3 °C. The results of the local air change index and air change efficiency for the nominal supply temperature of 17.6 °C showed that the system had strong characteristics of a mixing ventilation system. At the supply air temperature of 21.0 °C, the performance of the system deteriorated slightly to below that of a mixing ventilation system and could not satisfactorily provide heating at supply temperature of 25.3 °C. Better performance of the system at all supply air temperature setpoints was observed at lower airflow rates. At all supply air temperature setpoints, relatively higher degree of temperature stratification was observed at lower supply. The draught rate levels decreased with increase in supply air temperature and height. The location of the air inlet terminals in relation to the workstations had significant effect on the performance of the system. The stratum ventilation system did not work efficiently because the air streams were heavily mixed before reaching the occupants.

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Hillblom, Karin. "Ombyggnad av ventilation i kulturbyggnader". Thesis, KTH, Byggvetenskap, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-46321.

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I detta arbete studeras hur en systemombyggnad i kulturbyggnader kan gå till med avseende på installationerna. I Sverige finns det idag totalt ca 4,7 miljoner byggnader av vilka ca 235 000-280 000 bör genomgå kulturbevarande byggnadsvårdsinsatser. Vid ombyggnad av ventilationen i en kulturbyggnad är det viktigt att man, samtidigt som man får en ändamålsenlig och energisnål lösning, tar hänsyn till byggnadens karaktär och förutsättningar så att den kulturhistoriskt värdefulla miljön bevaras. I detta arbete studeras tre olika kulturhistoriskt värdefulla byggnader som genomgått renovering av ventilationssystemet under de senaste tio åren. Byggnaderna är Skridskopaviljongen, Dekanhuset och Södra Bancohuset, som alla förvaltas av Statens fastighetsverk (SFV). Efter samtal, studier och undersökningar om de tre byggnaderna visar det sig att det är viktigt att i början av en systemombyggnad i en kulturbyggnad, först läsa in sig på byggnaden samt ställa sig frågorna: vad ska byggnaden användas till, vilken verksamhet passar här, vilket systemval kommer att passa brukaren bäst mm. När man vet det, är det bra att ta kontakt med en antikvarie så tidigt som möjligt samt inventera byggnaden för att t.ex. få en bild av var gamla håltagningar finns och vilka kanaler som kan gå att använda. En fördjupad undersökning gjordes av Skridskopaviljongen, där simuleringar genomförts för att utreda om systemet som byggdes var bäst i ett LCC-perspektiv ”livscykelkostnad” (Life Cycle Cost) jämfört med två andra systemlösningar. Resultatet blev att det mest avancerade systemvalet inte behöver vara det bästa, utan om man uppfyller lagkraven för inomhusklimatet kan man använda sig av ett enklare system. Men då får man tänka på att om verksamheten i framtiden ändras måste inomhusklimatet fortfarande vara godkänt. Detta kan medföra viss systemombyggnad vid byte av hyresgäst. Varje kulturbyggnad är unik och olika delar i dem skyddas mer eller mindre av lagar om skydd av kulturvärden. Därför går det inte att göra en speciell checklista för hur man ska gå till väga, utan varje byggnad måste betraktas från fall till fall. En unik systemlösning får tas fram för varje unik byggnad.

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Kenton, Amanda Gail. "Natural ventilation in theatre design". Thesis, University of Cambridge, 2006. https://www.repository.cam.ac.uk/handle/1810/252011.

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Zou, Yue. "Air jets in ventilation applications". Doctoral thesis, Stockholm, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3146.

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MacKinnon, Ian R. (Ian Roderick) 1964. "Air distribution from ventilation ducts". Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59655.

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A wooden, perforated, uniform cross-section duct was examined to determine the optimum levels of aperture ratio and fan speed with respect to uniformity of discharge. The optimum aperture ratio for the 8.54 m long duct was 1.0 with a uniformity coefficient of 90.28%. The fan speed had little effect on the uniformity of discharge. The friction factor was experimentally determined to be 0.048 for a non-perforated duct and this value was assumed to be the same for a perforated duct of similar construction. A kinetic energy correction factor was used to analyze the flow in the duct. Values for this correction factor were determined from experimental data. Values of the coefficient of discharge and the total duct energy were calculated. A mathematical model was proposed based on the conservation of momentum and the Bernoulli's equation. The model responded favourably and predicted the duct velocity nearly perfectly and slightly underestimated the total duct energy.

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36

Li, Rong. "Natural ventilation of atrium spaces". Thesis, University of Sheffield, 2007. http://etheses.whiterose.ac.uk/6112/.

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This research is aimed to develop a series of design guidelines and relevant prediction tools for the incorporation of natural ventilation in atrium spaces as a passive cooling strategy. Focused on the geometrical and thermal characteristics of atrium buildings, four issues related to this purpose are investigated in this work including thermal comfort, wind-induced ventilation, buoyancy-induced ventilation and combined buoyancy and wind driven ventilation: In order to identify when passive cooling strategies are needed for atrium spaces, a new thermal comfort assessment method which enables the treatment of the solar radiation and non-uniform environment is developed using M.ATLAB as the data exchange platform. It is found that high mean radiant temperature (MRT) can be a more significant factor contributing to the thermal discomfort of the space when the internal occupants' level is irradiated by the sun rays. It is also shown that the air temperature at the occupants' level is mostly affected by the temperatures of the surfaces at lower levels and the temperatures at the roof level and the upper areas generally have little influence on the air temperature at the occupants' level. The study of wind-induced ventilation is concerned with the airflow through roof openings since the atrium is' often placed in the centre of a building andÃ‚Â· as a result the openings at lower levels are not available. In this way the air movement in the space is actually driven by the recirculation rather than the direct main flow from the wind. Three. possible flow patterns, and related controlling forces for each flow pattern are defined first, based on which the impacts of the design parameters on the ventilation performance are investigated by CFD techniques and design guidelines are developed accordingly. The effects of the location of heat source and the control of the neutral level when bidirectional flow occurs are studied for buoyancy-driven natural ventilation of atrium spaces. The tendency of the heat source efficiency with the variation of. its location is examined and the optimised location for the heat source is suggested, based on which the guidelines for the selection of materials for the atrium internal surfaces are made. A series of new' algorithms are also developed for the prediction of neutral level when bi-directional flows occur and validated with CFD simulations. The investigation of the combined ventilation focuses on the condition where wind forces and buoyancy forces partly assist each other and partly oppose each other, and it is found that the phenomenon of solution multiplicity still exists for this condition and different solutions may have different ventilation performance depending on the initial conditions.

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van, Drunen Erwin Johan. "Mechanical Ventilation Modelling and Optimisation". Thesis, University of Canterbury. Mechanical Engineering, 2013. http://hdl.handle.net/10092/8400.

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Acute Respiratory Distress Syndrome (ARDS) is associated with lung inflammation and fluid filling, resulting in a stiffer lung with reduced intrapulmonary gas volume. ARDS patients are admitted to the Intensive Care Unit (ICU) and require Mechanical Ventilation (MV) for breathing support. Positive End Expiratory Pressure (PEEP) is applied to aid recovery by improving gas exchange and maintaining recruited lung volume. However, high PEEP risks further lung injury due to overstretching of healthy lung units, and low PEEP risks further lung injury due to the repetitive opening and closing of lung units. Thus, selecting PEEP is a balance between avoiding over-stretching and repetitive opening of alveoli. Furthermore, specific protocols to determine optimal PEEP do not currently exist, resulting in variable PEEP selection. Thus, ensuring an optimal PEEP would have significant impact on patient mortality, and the cost and duration of MV therapy. Two important metrics that can be used to aid MV therapy are the elastance of the lungs as a function of PEEP, and the quantity of recruited lung volume as a function of PEEP. This thesis describes several models and model-based methods that can be used to select optimal PEEP in the ICU. Firstly, a single compartment lung model is investigated for its ability to capture the respiratory mechanics of a mechanically ventilated ARDS patient. This model is then expanded upon, leading to a novel method of mapping and visualising dynamic respiratory system elastance. Considering how elastance changes, both within a breath and throughout the course of care, provides a new clinical perspective. Next, a model using only the expiratory portion of the breathing cycle is developed and presented, providing an alternative means to track changes in disease state throughout MV therapy. Finally, four model-based methods are compared based on their capability of estimating the quantity of recruited lung volume due to PEEP. The models and model-based methods described in this thesis enable rapid parameter identification from readily available clinical data, providing a means of tracking lung condition and selecting optimal patient-specific PEEP. Each model is validated using data from clinical ICU patients and/or experimental ARDS animal models.

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Luo, Zhiwen, i 罗志文. "City ventilation by slope wind". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B46089962.

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Young, Peter Jeffrey. "Pulmonary aspiration in mechanical ventilation". Thesis, University of East Anglia, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323263.

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Pulmonary aspiration in mechanical ventilation occurs despite appropriate inflation of the tracheal tube cuff. After anaesthesiath is can causep ostoperative and, in critically ill patients, ventilator-associated pneumonia. Cuff over-inflation exerts excessive pressure on the tracheal mucosa causing injury. High volume low pressure (HVLP) cuffs permit wall pressure control as the intracuff pressure (CP) is the tracheal wall pressure (TWP). Unfortunately, at the cuff wall, folds and channels and, therefore, fluid leakage occur. Low volume high pressure (LVHP) cuffs develop neither folds nor associated leakage, but TWP is not easily inferred from CP and excessive pressures can result in tracheal injury. This thesis examines the problem of aspiration in a model, in anaesthetised patients and in the critically ill. In the model, protection against leakage resulted from positive end-expiratory pressure and cuff lubrication. Two tracheal cuff prototypes are introduced. Firstly, the compliant HVLP cuff is one with a tapered shape made of highly compliant material. Within the model this produced a circumferential band at the cuff wall without folds thus effectively eliminating channels and leakage. Secondly, the prototype pressure limited cuff (PLC) is a latex LVHP cuff with inflation characteristics such that TWP can be inferred from CP and maintained at an acceptable level. Within the model the PLC prevented leakage at acceptable TWPs. For clinical use a constant pressure inflation device is required to provide uninterrupted protection, although notably HVLP cuffs allow leakage despite this. The PLC prevented dye aspiration in 100% of tracheally intubated critically ill patients compared with 13% of the control HVLP group (p<0.01). A silicone cuff with similar inflation characteristics, yet improved biocompatability and shelf life, prevented dye aspiration in 100% of patients with tracheostomies compared to 0% of the HVLP control group (p=0.001). HVLP cuff lubrication delayed dye aspiration for 1 to 5 days (p<0.05).

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Young, John Duncan. "Gas movement during jet ventilation". Thesis, University of Southampton, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358708.

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Kobayashi, Nobukazu 1967. "Floor-supply displacement ventilation system". Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8688.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Architecture, 2001.
Includes bibliographical references (p. 104-106).
Research on indoor environments has received more attention recently because reports of symptoms and other health complaints related to indoor environments have been increasing. Heating, ventilating, and air-conditioning (HVAC) systems are used to control the indoor environment. Therefore, it is necessary to provide a good ventilation system that can provide good indoor environment. To improve indoor air quality, displacement ventilation systems can work well. The system provides fresh air directly to the occupied zone. However, the existing floor-supply displacement ventilation systems have some problems. Hence, the objective of this research was to improve the disadvantages of the current system, and to develop a new design for the floor-supply displacement ventilation system with floor diffusers. The research used numerical simulations through computational-fluid-dynamics (CFD). The experiment was carried out in a full -scale environmental chamber to obtain a reliable data on the floor-supply ventilation system. With the detailed data, the CFD program used in this research was validated. By using the validated program, we conducted numerical simulations of several different cases of the floor-supply system to evaluate the design and the performance of the system. The impacts of several parameters, such as the air change rate, number of diffusers, furniture arrangement, and cooling loads, on the indoor environment were investigated based on the thermal comfort level and indoor air quality. From the results, the parameters were ranked in the order of their impact. This result can be used for more specific case studies of each building design.
by Nobukazu Kobayashi.
S.M.

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Chen, Shaw-Bing. "Natural ventilation generates building form". Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/65048.

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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Architecture, 1996.
Includes bibliographical references (leaves 149-151).
Natural ventilation is an efficient design strategy for thermal comfort in hot and humid climates. The building forms can generate different pressures and temperatures to induce natural ventilation. This thesis develops a methodology that uses a computational fluid dynamics (CFD) program. The purpose of the CFD program is to assist architects to design optimum building form for natural ventilation. The design of a cottage in Miami, Florida demonstrates the application of this methodology. The first phase of this methodology is to create an input file for the CFD program. The input file uses wind velocity, wind direction, and air temperature of the site to simulate the weather. Different weather conditions can be generated through modification of the first input file. The second phase of this methodology is to develop building forms. The CFD programs can simulate airflow in different building forms by changing the building geometry in the input files. The program calculates the airflow pattern, velocity, and temperature for different forms. The printouts of the simulations allow architects to understand the airflow behavior in spaces with different forms. This thesis also uses the CFD program to study variance between the proposed and the actual results of a design. As demonstrated in a sports museum in Washington, DC, this case study clearly displays a difference between the intentions of the architect and the results of CFD calculation. Some problems appear in developing CFD models. However, when the input files are correctly defined, and the calculations converge, very few computational problems appear in developing building forms. Therefore, architects can easily use the CFD programs to develop building form after the input files are correctly defined.
by Shaw-Bing Chen.
M.S.

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Kuesters, Andrea Susanne. "A study of ventilation flows". Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607801.

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Vad-Schütt, Klockervold Beatrice. "Natural ventilation and behavioural differences". Thesis, KTH, Energiteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-192156.

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To open a window can feel natural when experiencing frowsty air, a high room temperature, or stuffiness. Regardless of the purpose of the natural ventilation, heat is being let out and thereby energy. The problem with this arises for instance when planning new real estate constructions when ventilation of this kind is an individual behaviour dependent factor, and thereby impossible to exactly predetermine. Today, a relatively unevaluated standard value is used for annual energy losses at 4 kWh/m2, but considering that these losses are hard to measure it is uncertain how well this number matches reality. Besides, the natural ventilation behaviour and the use of energy differs from household to household. The purpose was to examine the average natural ventilation behaviour in households, whether some groups of people ventilate more than others, which the reasons of ventilating are, how large effect one person’s ventilation behaviour can have on his or hers neighbours, and also how the needs of ventilation and the amount of used energy will look in the future. To answer this a thorough literature study, a couple of preparing interviews for the survey template, a survey about ventilating behaviour, and a simple example calculation about heat transferring through partition walls was done. Important results obtained from this is that: · Natural ventilation behaviour depend on both age and property. · Older age groups ventilate more than younger. People between 30-50 years ventilate half as much as people between 30-50 years and a third as much as people over 50.People between 50-70 years and older ventilate approximately equally. · People living in buildings of 10-50 m2 and over 100 m2 ventilate approximately equally while people in buildings of 50-100 m2 ventilate 35% more. · Detached houses and apartments are naturally ventilated as often but apartments are ventilated more than an hour longer each session, which results in that apartments are ventilated 50 % more. · 71 % of all people does not shut off their heating sources during natural ventilation. · Frowsty air represents 47 %, high room temperatures represents 35 % and the want to get closer to the outside nature in any way represents 14 % of the reasons for ventilating. · Heat conduction from one apartment to another due to natural ventilation costs at the most 37,23 SEK a year. In the long run the results from this survey with more additional and extensive examinations, could lead to more accurate standard values used in energy calculations for new constructions. Depending on property and probable age of future inhabitants less uncertain calculations could be made. Studies and analyses was limited to Nordic climate and especially to the second and third climate zones of Sweden. The main reason for this was that the participants of the survey and interviews resided in this area. Beside this, the only properties which has been analysed are residences and therefore not office buildings or other real estate’s not resided by people.
”Att öppna ett fönster” kan kännas naturligt vid upplevd dålig luft, för hög temperatur eller instängdhet. Men oavsett vad orsaken för vädring är så släpps värme ut och därmed energi vilket ger problem bland annat vid planering av byggnationer av nya fastigheter. Detta då vädring av detta slag är en individuell beteendeberoende faktor och därmed omöjlig att exakt förutbestämma. Idag används ett relativt outvärderat standardvärde från Boverket för energiförluster på 4 kWh/m2 per år men då dessa förluster är ytterst svåra att mäta är det oklart hur väl siffran stämmer överens med verkligheten. Dessutom skiljer sig vädringsbeteendet och energianvändningen åt från hushåll till hushåll. Syftet var att undersöka hur mycket bostäder vädras i genomsnitt, om vissa grupper av människor vädrar mer än andra, vad orsakerna till vädring är, vilken effekt en människas vädringsbeteende kan ha på intilliggande bostäders energianvändning, samt hur vädringsbehovet och mängden använd energi kommer se ut i framtiden. För att besvara detta gjordes en grundlig litteraturundersökning, ett antal intervjuer som förberedelse för en enkätmall, en enkätundersökning om vädringsbeteende, samt en enkel exempelberäkning om värmeöverföring från en bostad till en annan. Viktiga resultat som erhållits är att: · Vädringsbeteende beror av både ålder på de boende samt bostadstyp. · Äldre åldersgrupper vädrar i genomsnitt mer än yngre. Personer mellan 18- 30 år vädrar hälften så mycket som personer mellan 30-50 år och en tredjedel så mycket som personer över 50 år. Personer mellan 50-70 år och äldre vädrar ungefär lika mycket. · Personer i bostäder på 10-50 m2 och över 100 m2 vädrar ungefär lika mycket medan personer i bostäder på 50-100 m2 vädrar 35 % mer. · Friliggande villor och lägenheter vädras lika ofta men lägenheter vädras över en timme längre per vädringstillfälle vilket för den totala vädringstiden betyder att lägenheter vädras 50 % mer än villor. · 71 % i genomsnitt stänger inte av sina värmekällor under vädring. · Dålig luft, för höga inomhustemperaturer, och vilja att komma närmare naturen på något sätt står för 47 %, 35 % respektive 14 % av vädring. · Värmeöverföring från en lägenhet till en annan till följd av vädring kostar i extremfall max 37,23 kr per år. I det långa loppet kan resultatet från denna undersökning med fler kompletterande och omfattande sådana medföra mer korrekta standardvärden i energiberäkningar för nybyggnationer. Beroende på bostadstyp och trolig ålder för framtida inneboenden skulle mer riktiga beräkningar kunna göras. Undersökningar och analyser avgränsades till Nordiskt klimat och då främst till Sveriges 2a och 3e klimatzon. Orsaken till detta var främst att de tillfrågade i enkäten och intervjuerna var bosatta i detta område. Dessutom har endast bostäder analyserats och därmed exempelvis inte kontorshus eller andra fastigheter som inte innehar sådana.

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MacGilchrist, Graeme. "Lagrangian perspectives on ocean ventilation". Thesis, University of Oxford, 2017. http://ora.ox.ac.uk/objects/uuid:de6c14b7-a55c-44e7-8c2b-2f94a601ab8e.

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Within the global climate system, the ocean operates as a vast store of important components such as heat and carbon dioxide that it exchanges with the atmosphere on timescales from days to millennia. Its facility to do so is in large part due to the process of ocean ventilation by which water is moved from the surface mixed layer, where it is in contact with the atmosphere, and transported through the subsurface. An understanding of ocean ventilation, therefore, is crucial in establishing the magnitudes and timescales of ocean-atmosphere exchange. In this thesis, a predominantly Lagrangian approach is adopted, evaluating trajectories in an eddy-permitting numerical ocean circulation model to explore different aspects of the ventilation process. Following critical assessment of the fidelity of the trajectory analysis, a dynamical systems approach is applied to assess the role of ocean turbulence in the transport of ventilated water in the subsurface, with application to the subtropical gyre of the North Atlantic. The pathways of ventilation, represented by Lagrangian maps, are found to be highly chaotic and characterised by a non-dimensional filamentation number that compares the ventilation and filamentation timescales of the flow. Subsequently, the mechanisms and variability of ventilation of dense water masses in the high-latitude North Atlantic are considered, a crucial component in present-day oceanic uptake of heat and carbon dioxide. A Lagrangian approach allows us to link surface processes to their subsurface signature, and reveals that variations in annual re-entrainment establish substantial inter-annual variability in the water that enters the deep ocean. Furthermore, the results reveal that mechanisms of ventilation in the numerical simulation differ substantially from observations, with possible implications for the fidelity of future climate projections. Finally, the translation into the ocean interior of a biologically and chemically active tracer, such as carbon dioxide, is considered, and how this is dependent on the interaction between ventilation, circulation and biogeochemical processes. From observations in the Weddell Gyre, it is shown that biological export and the horizontal circulation are critical in sustaining regional uptake of carbon dioxide from the atmosphere. Broadly, these various results serve to emphasise the complexity of the ventilation process and its associated role in the oceanic storage of climate-relevant components, from the chaotic nature of pathways, short timescales of variability, its difficulty of representation in numerical models, and its interaction with the biogeochemical system.

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Schmidt, Andreas. "Atmung mit Pressure-Support-Ventilation und Proportional-Assist-Ventilation bei gesunden Probanden mit gesteigerter Elastance". [S.l.] : [s.n.], 1999. http://www.sub.uni-hamburg.de/disse/559/Disse.pdf.

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Chen, Huijuan. "Experimental and numerical investigations of a ventilation strategy – impinging jet ventilation for an office environment". Doctoral thesis, Linköpings universitet, Energisystem, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-106483.

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A well-functioning, energy-efficient ventilation system is of vital importance to offices, not only to provide the kind of comfortable, healthy indoor environment necessary for the well-being and productive work performance of occupants, but also to reduce energy use in buildings and the associated impact of CO2 emissions on the environment. To achieve these goals impinging jet ventilation has been developed as an innovative ventilation concept. In an impinging jet ventilation system, a high momentum of air jet is discharged downwards, strikes the floor and spreads over it, thus distributing the fresh air along the floor in the form of a very thin shear layer. This system retains advantages of mixing and stratification from conventional air distribution methods, while capable of overcoming their shortcomings. The aim of this thesis is to reach a thorough understanding of impinging jet ventilation for providing a good thermal environment for an office, by using Computational Fluid Dynamics (CFD) supported by detailed measurements. The full-field measurements were carried out in two test rooms located in a large enclosure giving relatively stable climate conditions. This study has been divided into three parts where the first focuses on validation of numerical investigations against measurements, the second addresses impacts of a number of design parameters on the impinging jet flow field and thermal comfort level, and the third compares ventilation performance of the impinging jet supply device with other air supply devices intended for mixing, wall confluent jets and displacement ventilation, under specific room conditions. In the first part, velocity and temperature distributions of the impinging jet flow field predicted by different turbulence models are compared with detailed measurements. Results from the non-isothermal validation studies show that the accuracy of the simulation results is to a great extent dependent on the complexity of the turbulence models, due to complicated flow phenomena related to jet impingement, such as recirculation, curvature and instability. The v2-f turbulence model shows the best performance with measurements, which is slightly better than the SST k-ω model but much better than the RNG k-ε model. The difference is assumed to be essentially related to the magnitude of turbulent kinetic energy predicted in the vicinity of the stagnation region. Results from the isothermal study show that both the SST k-ω and RNG k-ε models predict similar wall jet behaviours of the impinging jet flow. In the second part, three sets of parametric studies were carried out by using validated CFD models. The first parametric study shows that the geometry of the air supply system has the most significant impact on the flow field. The rectangular air supply device, especially the one with larger aspect ratio, provides a longer penetration distance to the room, which is suitable for industrial ventilation. The second study reveals that the interaction effect of cooling ceiling, heat sources and impinging jet ventilation results in complex flow phenomena but with a notable feature of air circulation, which consequently decreases thermal stratification in the room and increases draught discomfort at the foot level. The third study demonstrates the advantage of using response surface methodology to study simultaneous effects on changes in four parameters, i.e. shape of air supply device, jet discharge height, supply airflow rate and supply air temperature. Analysis of the flow field reveals that at a low discharge height, the shape of air supply device has a major impact on the flow pattern in the vicinity of the supply device. Correlations between the studied parameters and local thermal discomfort indices were derived. Supply airflow rates and temperatures are shown to be the most important parameter for draught and stratification discomfort, respectively. In the third part, the impinging jet supply device was shown to provide a better overall performance than other air supply devices used for mixing, wall confluent jets and displacement ventilation, with respect to thermal comfort, heat removal effectiveness, air exchange efficiency and energy-saving potential related to fan power.

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Latifi, Kujtim. "Assessment of the Dependence of Ventilation Image Calculation from 4D-CT on Deformation and Ventilation Algorithms". Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3197.

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Ventilation imaging using 4D-CT is a convenient and cost effective functional imaging methodology which might be of value in radiotherapy treatment planning to spare functional lung volumes. To calculate ventilation imaging from 4D-CT we must use deformable image registration (DIR). This study validates the DIR methods and investigates the dependence of calculated ventilation on DIR methods and ventilation algorithms. The first hypothesis is if ventilation algorithms are robust then they will be insensitive to the precise DIR used provided the DIR is accurate. The second hypothesis is that the change in Houndsfield Unit (HU) method is less dependent on the DIR used and depends more on the CT image quality due to the inherent noise of HUs in normal CT imaging. DIR of the normal end expiration and inspiration phases of the 4D-CT images was used to correlate the voxels between the two respiratory phases. All DIR algorithms were validated using a 4D pixel-based and point-validated breathing thorax model, consisting of a 4D-CT image data set along with associated landmarks. Three different DIR algorithms, Optical Flow (OF), Diffeomorphic Demons (DD) and Diffeomorphic Morphons (DM), were retrospectively applied to the same group of 10 esophagus and 10 lung cancer cases all of which had associated 4D-CT image sets that encompassed the entire lung volume. Three different ventilation calculation algorithms were compared (Jacobian, ΔV, and HU) using the Dice similarity coefficient comparison. In the validation of the DIR algorithms, the average target registration errors with one standard deviation for the DIR algorithms were 1.6 ± 0.7 mm, maximum 3.1 mm for OF, 1.3 ± 0.6 mm, maximum 3.3 mm for DM, 1.3 ± 0.6 mm, maximum 2.8 mm for DD, indicating registration errors were within 2 voxels. Dependence of ventilation images on the DIR was greater for the ΔV and the Jacobian methods than for the HU method. The Dice similarity coefficient for 20% of low ventilation volume for ΔV was 0.33 ± 0.03 between OF and DM, 0.44 ± 0.05 between OF and DD and 0.51 ± 0.04 between DM and DD. The similarity comparisons for Jacobian was 0.32 ± 0.03, 0.44 ± 0.05 and 0.51 ± 0.04 respectively, and for HU 0.53 ± 0.03, 0.56 ± 0.03 and 0.76 ± 0.04 respectively. Dependence of ventilation images on the ventilation method used showed good agreement between the ΔV and Jacobian methods but differences between these two and the HU method were significantly greater. Dice similarity coefficient for using OF as DIR was 0.86 ± 0.01 between ΔV and Jacobian, 0.28 ± 0.04 between ΔV and HU and 0.28 ± 0.04 between Jacobian and HU respectively. When using DM or DD as DIR, similar values were obtained when comparing the different ventilation calculation methods. The similarity values for 20% of the high ventilation volume were close to those found for the 20% low ventilation volume. Mean target registration error for all three DIR methods was within one voxel suggesting that the registration done by either of the methods is quite accurate. Ventilation calculation from 4D-CT demonstrates some degree of dependency on the DIR algorithm employed. Similarities between ΔV and Jacobian are higher than between ΔV and HU and Jacobian and HU. This shows that ΔV and Jacobian are very similar, but HU is a very different ventilation calculation method.

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Chatterjee, Arnab. "Optimization of mine ventilation fan speeds according to ventilation on demand and time of use tariff". Diss., University of Pretoria, 2014. http://hdl.handle.net/2263/45900.

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With the growing concerns about energy shortage and demand supply imbalance, demand side management (DSM) activities has found its way into the mining industry. This study analyzes the potential to save energy and energy-costs in underground mine ventilation networks, by application of DSM techniques. Energy saving is achieved by optimally adjusting the speed of the main fan to match the time-varying flow demand in the network, which is known as ventilation on demand (VOD). Further cost saving is achieved by shifting load to off-peak or standard times according to a time of use (TOU) tariff, i.e. finding the optimal mining schedule. The network is modelled using graph theory and Kirchhoff’s laws; which is used to form a non-linear, constrained, optimization problem. The objective of this problem is formulated to minimize the energy cost; and hence it is directly given as a function of the fan speed, which is the control variable. As such, the operating point is found for every change in the fan speed, by incorporating the fan laws and the system curve. The problem is solved using the fmincon solver in Matlab’s optimization toolbox. The model is analyzed for different scenarios, including varying the flow rate requirements and tariff structure. Although the results are preliminary and very case specific, the study suggests that significant energy and energy-cost saving can be achieved in a financially viable manner.
Dissertation (MEng)--University of Pretoria, 2014.
tm2015
Electrical, Electronic and Computer Engineering
MEng
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Koombua, Kittisak. "Multiscale Modeling of Airway Inflammation Induced by Mechanical Ventilation". VCU Scholars Compass, 2009. http://scholarscompass.vcu.edu/etd/1841.

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Mechanical ventilation (MV) is a system that partially or fully assists patients whose respiratory system fails to achieve a gas exchange function. However, MV can cause a ventilator-associated lung injury (VALI) or even contribute to a multiple organ dysfunction syndrome (MODS) in acute respiratory distress syndrome (ARDS) patients. Despite advances in today technologies, mortality rates for ARDS patient are still high. A better understanding of the interactions between airflow from mechanical ventilator and the airway could provide useful information used to develop a better strategy to ventilate patients. The mechanisms, which mechanical ventilation induces airway inflammation, are complex processes and cover a wide range of spatial scales. The multiscale model of the airway have been developed combining the computational models at organ, tissue, and cellular levels. A model at the organ level was used to study behaviors of the airway during mechanical ventilation. Strain distributions in each layer of the airway were investigated using a model at the tissue level. The cellular inflammatory responses during mechanical ventilation were investigated through the cellular automata (CA) model incorporating all biophysical processes during inflammatory responses. The multiscale modeling framework started by obtaining airway displacements from the organ-level model. They were then transferred to the tissue-level model for determining the strain distributions in each airway layer. The strain levels in each layer were then transferred to the cellular-level model for inflammatory responses due to strain levels. The ratio of the number of damage cells to healthy cells was obtained through the cellular-level model. This ratio, in turn, modulated changes in the Young’s modulus of elasticity at the tissue and organ levels. The simulation results showed that high tidal volume (1400 cc) during mechanical ventilation can cause tissue injury due to high concentration of activated immune cells and low tidal volume during mechanical ventilation (700 cc) can prevent tissue injury during mechanical ventilation and can mitigate tissue injury from the high tidal volume ventilation. The multiscale model developed in this research could provide useful information about how mechanical ventilation contributes to airway inflammation so that a better strategy to ventilate patients can be developed.

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