Tesis sobre el tema "Diaphragm"
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1
Orrey, Samantha Taylor. "The relationship between diaphragm thickness, diaphragm strength and diaphragm endurance in young, healthy individuals". Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86666.
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Thesis (MScPhysio)--Stellenbosch University, 2014.ENGLISH ABSTRACT: Introduction: In the intensive care unit population, approximately 40% of patients require mechanical ventilation and 20-25% of these patients will encounter difficulties in the discontinuation of mechanical ventilation. As mechanical ventilation affects the diaphragm, a better understanding of the structural and functional changes of the diaphragm is warranted. Method: A scoping review was done to determine whether a relationship between diaphragm thickness, diaphragm strength and diaphragm endurance had been established. Seven databases were searched using a specific search strategy. Papers were identified based on pre-defined inclusion criteria. Data was extracted by the primary investigator (PI) into a self-developed excel spreadsheet. Criteria were developed for a more focused review to inform the planning of a primary study. The primary study investigated the relationship between diaphragm thickness, diaphragm strength and diaphragm endurance in young, healthy individuals. A sample of convenience was used; included healthy individuals (18-24); three activity-levels (sedentary; endurance- and strength related sporting activities); stratified for gender and BMI. Measurements included: Sonographic measurement of diaphragm thickness; mouth pressure manometer measurements for diaphragmatic strength; and fatigue resistance index as a measure of endurance. Participants were instructed to breathe through a pressure threshold device at 60% of PImax until task failure. The fatigue resistance index was calculated as PImax final/PImax initial. Intra-rater reliability was established and testing procedures standardised a priori. Results: 405 full texts were retrieved and assessed for inclusion into the review. Papers identified the evaluation of diaphragm function in a variety of populations. 23 papers were included in the focused review. Six papers were published on diaphragm thickness, six on diaphragm strength and eleven on diaphragm endurance. No papers identified the correlation between diaphragm thickness, diaphragm strength and diaphragm endurance. 55 subjects, males and females, were recruited for the primary study. Groups were similar at baseline with regards to gender, age and BMI. The mean age of the sample was 21.16 years (SD = 1.55), with a mean body mass index (BMI) of 25.43 kg/m2 (SD = 3.70). A moderate positive correlation was established between diaphragm thickness and diaphragm strength measurements (r = 0.52; r2 = 0.27; p < 0.01). Diaphragm thickness was not correlated with diaphragm endurance (r = -0.15; r2 = 0.02; p = 0.29). No relationship was found between the strength of the diaphragm and the endurance of the diaphragm (r= -0.19; r2 = 0.04; p= 0.16). Conclusion: Guidelines for the measurement of diaphragm function do exist, but they are not adhered to by the majority of studies. Study procedures are inconsistently reported and this may affect the reproducibility of techniques in future studies. We further conclude that a correlation exists between diaphragm thickness and diaphragm strength. The use of ultrasound to measure diaphragm thickness proved to be a reliable technology and gave a moderate indication of the strength of the diaphragm. This technology may help clinicians to detect and monitor dysfunction of the diaphragm in the early stages of admission to the acute setting.
AFRIKAANSE OPSOMMING: Inleiding: Ongeveer 40% van pasiente wat in intensiewe sorgeenheid behandel word, benodig intubasie en meganiese ventilasie. Tot 25% van hierdie pasiënte sal probleme ondervind in die staking van meganiese ventilasie. Meganiese ventilasie beïnvloed die diafragma, daarom word n beter begrip van die strukturele en funksionele veranderinge van die diafragma benodig. Metode: 'n Literatuur oorsig is gedoen om te bepaal of daar 'n verhouding bestaan tussen die dikte, krag en uithouvermoë van die diafragma. Sewe databasisse is deurgesoek aan die hand van spesifieke databasis gedefinieerde soektog strategie. Relevante artikels is geïdentifiseer aan die hand van pre-gedefinieerde insluiting kriteria. Data is onttrek en in ‘n self-ontwikkelde datablad opgesom deur die primêre ondersoeker (PI). Hierdie inligting is gebruik in die beplanning van ‘n primêre studie. Die doel van die primêre studie was om die verhouding tussen die diafragma dikte, krag en uithouvermoë in jong, gesonde individue te ondersoek. ‘n Gerieflikheids steekproef is gebruik; insluitend gesonde individue (18-24); drie aktiwiteits vlakke (passief; uithouvermoë- en krag verwante sportaktiwiteite) en breë spektrum vir geslag en ligaamsbou (BMI). Metings ingesluit: sonografiese meting van die diafragma se dikte; monddruk manometer metings vir diafragmatiese krag en ‘n moegheid/weerstand indeks as maatstaf van diafragmatiese uithouvermoë. Deelnemers is opdrag gegee om asem te haal deur toestel met druk maksimum gestel 60% van PImax, tot mislukking. Die moegheid/weerstand indeks is bereken as PImax finale / PImax oorspronlik. Intra-meter betroubaarheid is bepaal en toets prosedures is gestandaardiseer voordat data ingesamel is. Resultate: 405 vol teks artikels is uitgelig vir insluiting in die literatuur oorsig. Diafragmatiese funksie is ge-evalueer in 'n verskeidenheid bevolkings. Drie en twintig artikels is in die finale oorsig ingesluit. Ses artikels wat diafragma dikte evalueer, ses wat diafragmatiese krag evalueer en elf wat die diafragma se uithouvermoë evalueer is ingesluit in die oorsig. Geen van die artikels uitgelig het ‘n ooreenkoms tussen diafragma dikte, diafragma krag en diafragma uithouvermoë geïdentifiseer nie. 55 deelnemers is gewerf vir die primêre studie. Groepe was soortgelyk by basislyn met betrekking tot geslag, ouderdom en BMI. Die gemiddelde ouderdom van die toetsgroep was 21.16 jaar (SD=1.55), met 'n gemiddelde BMI van 25.43 kg/m2 (SD = 3.70). ‘n Middelmatige positiewe verhouding is waargeneem tussen diafragma dikte en krag (r = 0.52; r2 = 0.27; p < 0.01). Geen verhouding is gevind tussen diafragma dikte en uithouvermoë nie (r= -0.15; r2 = 0.02; p = 0.29). Daar is ook geen verhouding waargeneem tussen diafragma krag en diafragma uithouvermoë nie. (r= 0.19; r2 = 0.04; p = 0.16). Gevolgtrekking: Daar bestaan wel riglyne vir die meting van die diafragma se funksie, maar in die meerderheid van studies word dit nie nagekom nie. Studie prosedures is nie konsekwent weergegee nie en dit kan die resultate van tegnieke beinvloed in toekomende studies. ‘n Matige sterk verhouding is waargeneem tussen diafragmatiese dikte en krag. Die gebruik van ultraklank om die diafragma se dikte te meet is betroubare tegnologie en kan n redelike aanduiding gee oor die krag van die diafragma. Hierdie tegnologie kan praktisyne help om enige disfunksie van die diafragma te identifiseer en te monitor in die vroeë stadiums van toelating tot die akute omgewing.
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Singh, Bhajan. "The function of the human diaphragm as a volume pump and measurement of its efficiency /". Connect to this title, 2003. http://theses.library.uwa.edu.au/adt-WU2004.0029.
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O'Brien, Patrick Emmet. "Characterizing the Load-Deformation Behavior of Steel Deck Diaphragms using Past Test Data". Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/78679.
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Recent research has identified that current code level seismic demands used for diaphragm design are considerably lower than demands in real structures during a seismic event. However, historical data has shown that steel deck diaphragms, common to steel framed buildings, perform exceptionally well during earthquake events. A new alternative diaphragm design procedure in ASCE 7-16 increases diaphragm seismic demand to better represent expected demands. The resulting elastic design forces from this method are reduced by a diaphragm design force reduction factor, Rs, to account for the ductility of the diaphragm system. Currently, there exist no provisions for Rs factors for steel deck diaphragms. This research was therefore initiated to understand inelastic steel deck diaphragm behavior and calculate Rs factors.
A review of the literature showed that a large number of experimental programs have been performed to obtain the in-plane load-deformation behavior of steel deck diaphragms. To unify review of these diaphragm tests and their relevant results, a database of over 750 tested specimens was created. A subset of 108 specimens with post-peak, inelastic behavior was identified for the characterization of diaphragm behavior and ductility. A new recommended method for predicting shear strength and stiffness for steel deck diaphragms with structural concrete fill is proposed along with an appropriate resistance factor. Diaphragm system level ductility and overstrength are estimated based on subassemblage test results and Rs factors are then calculated based on these parameters. The effects of certain variables such as deck thickness and fastener spacing on diaphragm ductility are explored.Master of Science
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Bott, James Wescott. "Horizontal Stiffness of Wood Diaphragms". Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/32641.
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An experimental investigation was conducted to study the stiffness of wood diaphragms. Currently there is no method to calculate wood diaphragm stiffness that can reliably account for all of the various framing configurations. Diaphragm stiffness is important in the design of wood framed structures to calculate the predicted deflection and thereby determine if a diaphragm may be classified as rigid or flexible. This classification controls the method by which load is transferred from the diaphragm to the supporting structure below.
Multiple nondestructive experimental tests were performed on six full-scale wood diaphragms of varying sizes, aspect ratios, and load-orientations. Each test of each specimen involved a different combination of construction parameters. The construction parameters investigated were blocking, foam adhesive, presence of designated chord members, corner and center sheathing openings, and presence of walls on top of the diaphragm.
The experimental results are analyzed and compared in terms of equivalent viscous damping, global stiffness, shear stiffness, and flexural stiffness in order to evaluate the characteristics of each construction parameter and combinations thereof. Recommendations are presented at the end of this study as to the next steps toward development of an empirical method for calculating wood diaphragm stiffness.Master of Science
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Zhu, Ercheng. "Exercise-induced diaphragm sarcolemmal injury". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0013/NQ52201.pdf.
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Singh, Bhajan. "The function of the human diaphragm as a volume pump and measurement of its efficiency". University of Western Australia. School of Biomedical and Chemical Sciences, 2004. http://theses.library.uwa.edu.au/adt-WU2004.0029.
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[Truncated abstract] The function of the diaphragm as a volume pump has not been adequately evaluated because there are no accurate methods to measure the volume displaced by diaphragm motion (ΔVdi). As a consequence, the work done, power output and efficiency of the diaphragm have not been measured. Efficiency of the diaphragm could be measured by relating the power output of the diaphragm to its neural activation. The aims of this thesis were to (a) develop a new biplanar radiographic method to measure ΔVdi and use this to evaluate the effect of costophrenic fibrosis and emphysema on ΔVdi, (b) develop a new fluoroscopic method to enable breath-by-breath measurements of ΔVdi, (c) evaluate a method for quantifying neural activation of the diaphragm, and (d) combine measurements of transdiaphragmatic pressure, ΔVdi, inspiratory duration and neural activation of the diaphragm to quantify the neuromechanical efficiency of the diaphragm
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Leong, Hong Sai. "Prediction of deformation of diaphragm wall". Thesis, University of Macau, 2001. http://umaclib3.umac.mo/record=b1445039.
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Radell, Peter J. "Studies of diaphragm fatigue and dysfunction /". Stockholm, 2001. http://diss.kib.ki.se/2001/91-628-4751-1/.
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Huang, Xinlei. "Diaphragm stiffness in wood-frame construction". Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/43908.
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This thesis presents an investigation of the in-plane stiffness of wood-frame diaphragms. Studying the stiffness of the diaphragm is important since it affects the distribution of lateral loads to shear walls. In order to determine the force in each shear wall, it is common to classify a diaphragm as either flexible in engineering design. Wood-frame diaphragms have generally been treated as flexible, which distributes the lateral loads using the straightforward “tributary area” approach. The accuracy of this assumption is investigated in this study.
A detailed numerical model is developed for the study of the in-plane behaviour of wood-frame diaphragms. The model is validated with full-scale diaphragm tests, which has not been done so far for other diaphragm models in previous studies. As such, the model can be used as a “virtual laboratory” to predict the in-plane behaviour of wood-frame diaphragms with various configurations. A simplified model is developed based on the detailed diaphragm model to be used in the building analysis. The simplified model consists of “truss units”, which can be calibrated using analytical methods. In previous studies, wood-frame diaphragms were generally simplified as beam or spring models, where individual calibration is required for diaphragms with various configurations. Compared with these models, the simplified model developed here is obtained as an assembly of truss units, thus the number of calibration times can be considerably reduced. A case study of a one-storey wood-frame building is conducted to investigate the distribution of lateral loads to shear walls under different diaphragm flexibility conditions. It is found that the wood-frame diaphragm in this work is rather rigid, but is found that the distribution of lateral loads to the shear walls is strongly dependent on the relative stiffness of the diaphragm and the shear walls.
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Sheffy, Jacob. "Recording of diaphragm activity during anaesthesia". Thesis, Oxford Brookes University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261673.
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Cruickshank, Jane Laura. "A vibrating silicon diaphragm micro gyroscope". Thesis, University of Newcastle Upon Tyne, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285737.
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Ottenheijm, Coen, Leo Heunks y Richard Dekhuijzen. "Diaphragm adaptations in patients with COPD". BioMed Central, 2008. http://hdl.handle.net/10150/610242.
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Inspiratory muscle weakness in patients with COPD is of major clinical relevance. For instance, maximum inspiratory pressure generation is an independent determinant of survival in severe COPD. Traditionally, inspiratory muscle weakness has been ascribed to hyperinflation-induced diaphragm shortening. However, more recently, invasive evaluation of diaphragm contractile function, structure, and biochemistry demonstrated that cellular and molecular alterations occur, of which several can be considered pathologic of nature. Whereas the fiber type shift towards oxidative type I fibers in COPD diaphragm is regarded beneficial, rendering the overloaded diaphragm more resistant to fatigue, the reduction of diaphragm fiber force generation in vitro likely contributes to diaphragm weakness. The reduced diaphragm force generation at single fiber level is associated with loss of myosin content in these fibers. Moreover, the diaphragm in COPD is exposed to oxidative stress and sarcomeric injury. This review postulates that the oxidative stress and sarcomeric injury activate proteolytic machinery, leading to contractile protein wasting and, consequently, loss of force generating capacity of diaphragm fibers in patients with COPD. Interestingly, several of these presumed pathologic alterations are already present early in the course of the disease (GOLD I/II), although these patients appear not limited in their daily life activities. Treatment of diaphragm dysfunction in COPD is complex since its etiology is unclear, but recent findings indicate the ubiquitin-proteasome pathway as a prime target to attenuate diaphragm wasting in COPD.
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Sullivan, Rory Daniel. "Sound insulation of brick diaphragm walls". Thesis, University of Liverpool, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318231.
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Kazadi, Dieudonne Matang'a. "Non-Newtonian losses through diaphragm valves". Thesis, Cape Peninsula University of Technology, 2005. http://hdl.handle.net/20.500.11838/904.
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Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology, 2005The prediction of head losses in a pipe system is very important because head losses affect the performance of fluid machinery such as pumps. In a pipe system, two kinds of losses are observed: major losses and minor losses. In Newtonian and non-Newtonian flow, major losses are those that are due to friction in straight pipes and minor losses are those that are due to pipe fittings such as contractions, expansions, bends and valves. Minor losses must be accurately predicted in a pipe system because they are not negligible and can sometimes outweigh major losses (Edwards et al., 1985). There is presently little data for the prediction of non-Newtonian head losses in pipe fittings in the literature and little consensus amongst researchers (Pienaar et al., 2004). In the case of diaphragm valves, usually, only one loss coefficient value is given in turbulent flow or in laminar flow with no reference to a specific size of the valve, assuming geometrical similarity that would lead to dynamic similarity. However, no one has done a systematic study of various sizes of diaphragm valves from the same manufacturer to establish if this is true. This could be the main reason for discrepancies found in the literature (Hooper, 1981; Perry & Chilton, 1973; Miller, 1978 and Pienaar et al., 2004). This work addresses this issue. A literature revIew on the flow of Newtonian and non-Newtonian fluids has been presented. The work of Hooper (1981) on diaphragm valves and the works of Edwards et al., (1985), BaneIjee et aI., (1994) and Turian et al., (1997) for non-Newtonian fluids in globe and gate valves were found to be relevant to this work.
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Dres, Martin. "Evaluation et impact de la dysfonction diaphragmatique au cours du sevrage de la ventilation mécanique chez le patient adulte de réanimation". Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066253/document.
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La dysfonction diaphragmatique, au même titre que la neuromyopathie de réanimation qui touche les membres périphériques sont des causes fréquemment impliquées dans l'échec du sevrage de la ventilation mécanique. Des données suggèrent que ces deux atteintes sont le reflet d'une même affection ayant un tropisme respiratoire et locomoteur. Cette thèse met en évidence que la dysfonction diaphragmatique et la neuromyopathie de réanimation sont deux atteintes distinctes dont la coexistence est relativement faible. De plus, la dysfonction diaphragmatique a un impact délétère plus important sur le sevrage et le pronostic vital que la neuromyopathie de réanimation. Toutefois, le niveau de fonction diaphragmatique requis pour permettre une séparation du ventilateur est plus faible que le niveau de fonction définissant la dysfonction diaphragmatique. Ce travail montre également que l'exploration de la fonction diaphragmatique peut être simplifiée par l'utilisation de l'échographie et de l'électromyographie du diaphragmeDiaphragm dysfunction and critical illness associated neuropathy and myopathy are frequently suspected to cause weaning failure from mechanical ventilation. Some data suggest that both may be gathered into a same entity with two localisations, respiratory and peripheral. This thesis highlights that diaphragm dysfunction and critical illness neuromyopathy are two distinct diseases that don’t frequently coexist. In addition, diaphragm dysfunction has a more severe impact on weaning outcome and prognosis than critical illness associated neuromyopathy and myopathy. However, the level of diaphragm function required to ensure safe mechanical ventilation discontinuation is lower than the level of diaphragm function defining diaphragm dysfunction. This work also shows that investigating diaphragm function may be simplified by the use of ultrasound and diaphragm electromyogram activity
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Evcil, E. Hilal Malas Mehmet Ali. "Fetal dönem boyunca Diaphragma gelişimi /". Isparta : SDÜ Sağlık Bilimleri Enstitüsü, 2005. http://tez.sdu.edu.tr/Tezler/TT00205.pdf.
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Reid, Wendy Darlene. "Fatigue and rest of the hamster diaphragm". Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/29168.
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Decreased respiratory muscle strength and/or excessive loads imposed on the respiratory muscles by disease may result in respiratory muscle fatigue and ventilatory failure. Once the respiratory muscles fatigue, the only treatment is rest by mechanical ventilation. However, no one has yet determined the best protocol of rest. The purpose of these studies was to develop an animal model in the hamster in order to examine the time course of recovery following fatigue of the diaphragm and specifically, to test whether mechanical ventilation or spontaneous unloaded breathing was a better mode for functional recovery. The studies required the initial development of an anesthetic regimen which produced minimal respiratory depression in the hamster. A new method of stimulating the diaphragm in small animals was developed by apposing plate electrodes directly against the diaphragm. The validity of this technique was examined and comparison of the mechanical and electrophysiological response to that of phrenic nerve stimulation were similar at maximal stimulation. The histological characteristics of the normal hamster diaphragm were determined for fibre type proportions and sizes, oxidative capacity and glycogen levels in the costal and crural regions of this muscle. The examination revealed three distinct areas of the diaphragm with different histological features: the abdominal surface of the crural region, the thoracic surface of the crural region and the sternal and costal region. Diaphragmatic fatigue was induced in vivo by repetitive electrical stimulation which resulted in both high and low frequency fatigue. The fatigue stimulus also produced muscle fibre damage, primarily along the abdominal surface of the diaphragm over the electrodes, and glycogen depletion in the type lib fibres. Rest by continuous mechanical ventilation resulted in recovery of high frequency fatigue in the hamster diaphragm whereas rest by spontaneous unloaded breathing resulted in no recovery. Sham fatigue groups rested by either mechanical ventilation or spontaneous breathing demonstrated progressive deterioration in transdiaphragmatic pressure throughout the rest period. Decreased muscle fibre damage but increased inflammation and glycogen depletion was demonstrated in all four fatigue/sham fatigue and rest groups compared to that demonstrated by the fatigue/sham fatigue only groups. The results suggest that passive rest by continuous mechanical ventilation promotes recovery following fatigue induced by electrical stimulation. Additional factors such as prolonged fasting, loads imposed on the diaphragm by the plate electrode apparatus, positive pressure ventilation, and cumulative effects of intraperitoneal urethane likely contributed to the progressive deterioration of diaphragmatic function demonstrated in the animals of the two sham groups rested by either spontaneous breathing or mechanical ventilation, and confounded the results shown by the two fatigue groups rested by either spontaneous breathing or mechanical ventilation.Medicine, Faculty of
Pathology and Laboratory Medicine, Department of
Graduate
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Beck, Jennifer. "Measurement of diaphragm myoelectric activity in humans". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0007/NQ44360.pdf.
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Koch, Wijnandus Franciscus Robertus Maria. "Early development of the human pelvic diaphragm". Enschede : University of Twente [Host], 2006. http://doc.utwente.nl/57608.
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Beck, Jennifer 1968. "Measurement of diaphragm myoelectric activity in humans". Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=34912.
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This thesis is about the development and evaluation of a standardized method to measure the crural diaphragm electromyogram (EMG) in humans, with an esophageal electrode. In order for the diaphragm EMG to be physiologically relevant, its measurement and analysis require objective control of the disturbances and filter effects which can influence the sigma. One issue of importance is the maintenance of diaphragm-to-electrode positioning throughout the inspiration. In the present work, we describe a cross-correlation algorithm by which the position of the diaphragm along a multiple army esophageal electrode can be determined at any instant during a breath, and a second algorithm, the "double subtraction technique", which further minimizes the detrimental effects of diaphragm movement. The double subtraction technique also results in the improvement of the diaphragm EMG signal to noise ratio by 2 dB. By implementing these algorithms, we demonstrate in healthy subjects that there is no artifactual influence of lung volume/chest wall configuration on the diaphragm EMG frequency content nor on the diaphragm EMG signal strength during voluntary isometric contractions of the diaphragm. This is in contrast to the electrically elicited diaphragm compound muscle action potentials which are severely influenced by changes in lung volume. We also show that the volume-activation relationship of the diaphragm (required change in activation for changes in lung volume at a given tension) is directly related to the length-tension properties of the muscle. During dynamic, voluntary breathing maneuvers, we could find no evidence for an increase in diaphragm EMG signal strength when inspirations from functional residual capacity to total lung capacity (TLC) were performed at increasing inspiratory flow rates (velocities of shortening) up to 1.4 l/s. To account for anatomical and physiological differences between subjects, we demonstrate that the diaphragm EMG signal strength can be no
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Powrie, W. "The behaviour of diaphragm walls in clay". Thesis, University of Cambridge, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372634.
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Herlihy, Michael D. "Precast concrete floor support and diaphragm action". Thesis, University of Canterbury. Engineering, 1999. http://hdl.handle.net/10092/9578.
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Experimental research, engineering analysis and theoretical developments comprise a study in which various interactions between ductile moment resisting frames and precast prestressed hollow core flooring have been examined. The most critical interaction tested involves support behaviour, and the ability of reinforcing details to provide control against loss of support and possible catastrophic flooring collapse under dilation effects. Plastic hinge dilation, also known as elongation or growth, is an inherent property of ductile concrete members when subjected to cyclic plastic deformations. Hence, the performance of floor support details is enveloped by the general design philosophy of seismic resisting structures. In the experimental phase, emphasis was placed on testing support construction joints from contemporary building practice, for direct comparison with special support tie details of known capabilities. The contemporary details were found to exhibit seriously flawed behaviour under monotonic and cyclic loading regimes.
Corroborative experiments were undertaken to establish direct shear capacities between typical composite bond surfaces. In particular, these tests addressed the discrepancy that has emerged between direct shear and shear flow strengths. Also, the continuity response of conventional and proposed support detail types was examined.
A composite section model was analysed to demonstrate the likely influence of prestressing steel on beam bending strength within a ductile frame environment. Likewise, the probable effects of prestressing steel on beam plastic hinge development were examined, but on a more theoretical basis.
Other elements of theory have been presented. These mainly concern the general topic of elastic-plastic response in reinforced concrete elements. The particular focus of this work has been to demonstrate a rational basis to stiffness transition and plastic buckling analysis. The important role of stiffness degradation in dynamic analysis has also been examined.
Although ductile moment resisting concrete frames have been emphasised, it is considered that the findings of this thesis are applicable to other structural systems, such as dry joint "hybrid" precast concrete frames and spring connected steel frame structures.
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Omar, Wahid. "Diaphragm action in precast concrete floor construction". Thesis, University of Nottingham, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254392.
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Montague, T. I. "Concrete blockwork diaphragm walls - prestressed and unprestressed". Thesis, University of Manchester, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293672.
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Mulligan, Mark Thomas. "Protein turnover in the isolated mouse diaphragm". Thesis, University of Liverpool, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328161.
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Polkey, Michael Iain. "Diaphragm function in chronic obstructive pulmonary disease". Thesis, King's College London (University of London), 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286262.
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Masuda, Toru. "Behavior of deep excavation with diaphragm wall". Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/12172.
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Iqbal, Qaiser. "The performance of diaphragm type cellular cofferdams". Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/73612/.
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The construction of water management and navigation structures often requires temporary works to exclude water to facilitate construction in the dry or at least under a lower water level within the construction area. The use of cellular cofferdams for both temporary and permanent earth/water retaining works is very common. A number of theories are presented that describe the failure mechanisms involved. These failure mechanisms were identified from model studies on circular type cofferdams are applied independent of cofferdam geometry. It is common to use diaphragm type cofferdams. To asses the validity of common failure mechanisms associated with cellular cofferdams when applied to diaphragm type cofferdams, a series of numerical modelling analyses were conducted. These were validated using field monitoring results of a large scale diaphragm type cofferdam constructed at St. Germans, Norfolk, UK. A series of plane strain analyses of a diaphragm type cofferdam were conducted using the geometry from a critical section of cofferdam. These analyses identified the lowest factor of safety based on the drained strength of the clay on which the cofferdam was constructed. The water level within the river was increased to accommodate flooding and soil strength was reduced to identify the general failure mechanism. The structural forces were calculated using both 2D and 3D models for a larger width section (13m wide) to allow comparison with wall bending moments and displacements measured in field. The 3D analyses used actual tie spacing and membrane effects whilst reducing the lateral stiffness of the wall to accommodate the stiffness reduction due to variation in the interlock forces. To measure the bending moment in sheet piles, resistance type strain gauges were installed on a 13m wide section of cofferdam. The cell deflection, river and cell water levels were also monitored to identify tidal river effect and the influence of cell water level on performance. Comparison of field and numerical results highlighted a number of important design and construction detail related to diaphragm type cellular cofferdams.
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Samples, Matthew W. "Micro Electrostatic Actuation of a Silicon Diaphragm". DigitalCommons@CalPoly, 2015. https://digitalcommons.calpoly.edu/theses/1432.
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There are a number of applications, from hearing aids to microfluidic pumps, which utilize micro-scale actuating diaphragms. These MEMS (micro-electromechanical system) devices can be actuated by electrostatic forces, which utilize an induced electric field to pull two charged plates towards one another. Such devices were fabricated and electrostatic actuation of the diaphragms was performed to analyze its viability as a micro-speaker. The long-term performance of such products requires adequate diaphragm deflection to create audible pressure waves with relatively low maximum stresses to ensure a high cycle fatigue life. With these requirements, initial calculations and FEA (finite element analysis) were performed to establish the optimal square diaphragm side length combined with an attainable gap between electrodes to achieve an audible response. Optical and acoustic testing was then performed on 4, 5, and 7 mm side length square diaphragms with 10 μm thickness and a 70 μm electrode gap. For the 5 mm device and a 300 V applied potential, deflection was calculated to be 4.12 μm theoretically and 3.82 μm using FEA, although deflections based on optical test data averaged 30.53μm under DC conditions. The DAQ used for optical testing was extremely limiting due to its fastest sampling interval of 89 milliseconds, so this testing was performed at 2 and 5 Hz. Although the 7 mm device generated audible noise at 300 V and 2 kHz when the observer was within approximately 6 inches of the device, acoustic testing with a microphone placed 1 inch from the device did not yield any definitive results.
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Dridi, Haikel. "Mécanismes cellulaires précoces impliqués dans la dysfonction diaphragmatique induite par la ventilation mécanique". Thesis, Montpellier, 2016. http://www.theses.fr/2016MONT4005/document.
Texto completoResumen
La ventilation mécanique(VM) est le premier traitement en réanimation du syndrome de détresse respiratoire aigüe permettant de maintenir une oxygénation tissulaire suffisante. Mais elle induit une atteinte de la fonction contractile des muscles respiratoires, principalement le diaphragme, augmentant ainsi la dépendance du patient vis à vis de son ventilateur. Cette pathologie musculaire acquise est appelée Dysfonction Diaphragmatique induite par la ventilation (VIDD). L’objectif de cette thèse est proposer, à partir d’un modèle murin de ventilation mécanique, les mécanismes physiopathologiques précoces impliqués dans cette dysfonction, afin d’identifier de nouvelles cibles thérapeutiques dans la prévention de cette pathologie musculaire.Nous avons montré en effet la présence, après 6 heures de ventilation mécanique chez la souris, d’un stress oxydant d’origine mitochondrial à la base d’une oxydation du récepteur à la ryanodine (RyR1), principal canal calcique impliqué dans le CEC. Nous avons également montré la présence au bout d’un temps de ventilation mécanique équivalent, d’une phosphorylation de ce même canal, du faite d’une activation de la voie des protéines kinase, secondaire à un stress adrénergique. Nous également avons démontré que ces deux modifications post traductionnelles du RyR1 devaient être nécessairement associées pour induire une atteinte fonctionnelle du canal avec fuite calcique dans le cytosol, du faite de la perte de liaison avec sa protéine stabilisatrice FKBP12. Dans ses travaux de thèse, nous montrons également, que ces anomalies de troubles de l’homéostasie calcique observée après 6 heures de ventilation mécanique, induisaient au bout de 12 heures de ventilation une activation secondaire de la protéolyse dépendante du calcium, associée à une atrophie. Ainsi ces résultats montrent l’intérêt de toutes thérapeutiques permettant de stabiliser la liaison entre le canal RyR1 et sa protéine FKBP12 dans la prévention de la VIDD. En effet, avons observé chez la souris, qu’un traitement anti oxydant spécifique de la mitochondrie (SS-31) ou qu’un traitement bétabloquant spécifique de la voie béta2 adrénergique (ICI-118551) ou qu’un traitement qui stabilise directement la liaison RyR1-FKBP12 (S107) permettaient de prévenir les troubles précoces de l’homéostasie calcique et l’apparition secondaire d’une protéolyse et d’une atrophie induite par la ventilation mécanique. Enfin, dans le dernier travail de ma thèse, je propose que la production de ROS mitochondriale, puisse être associée à un remodelage du réseau mitochondrial avec prépondérance d’un phénomène de fission des mitochondries. Ce remodelage, qui pourrait être considéré comme une adaptation de la mitochondrie du faite d’une rupture brutale de l’équilibre entre production et consommation d’énergie par la fibre musculaire. En effet, nous montrons qu’un inhibiteur de la fission mitochondriale (P110), qui bloque la liaison entre la protéine Drp1 et son récepteur, dans notre modèle animal de ventilation mécanique, pouvait prévenir l’apparition d’une VIDD. Ainsi dans la continuité de ses derniers travaux, afin de faire le lien entre fission mitochondriale et stress oxydant à la base des troubles de l’homéostasie calcique, j’espère montrer que ce traitement, au cours de la ventilation mécanique, limite la production de ROS mitochondriale, l’oxydation du canal RyR1, ainsi que la fuite calcique à travers le RyR1. Ces derniers travaux, mettraient en avant toute thérapeutique permettant de limiter les phénomènes de fission mitochondriale et ses conséquences dans la prévention de la VIDD.Mots clés : RyR, mitochondrie, dysfonction contractile, VIDD, stress oxydantMechanical ventilation (MV) is the first treatment in intensive care for acute respiratory distress syndrome to maintain adequate tissue oxygenation. However, it induces an impairment of the contractile function of the respiratory muscles, particularly the diaphragm, thereby increasing the patient's dependence on his ventilator. This acquired muscle disease have been termed ventilator induced diaphragmatic dysfunction (VIDD). The aim of this thesis is to propose, from a mouse model of mechanical ventilation, early pathophysiologic mechanisms involved in this dysfunction, to identify new therapeutic targets in preventing VIDD.We observed after 6 hours of mechanical ventilation, a mitochondrial oxidative stress which induces ryanodine receptor (RyR1) oxidation, the main calcium channel involved in the ECC. We also showed the presence after an equivalent time of mechanical ventilation, phosphorylation of RyR1, due to protein kinase activation, secondary to an adrenergic stress. Then, we have demonstrated that these post-translational modifications of RyR1 should be necessarily associated to trigger a functional impairment of RyR1 with calcium leakage from the sarcoplasmic reticulum to the cytosol, due to the loss of connection between RyR1 and the stabilizing protein KBP12. In his thesis, we also showed that these calcium homeostasis disorders, induced by 12 hours of ventilation, secondary activates the dependent proteolysis calcium and atrophy.Thus, these results show the benefit of all therapy stabilizing the connection between the RyR1 channel and the FKBP12 protein to prevent VIDD. Indeed, were observed in mice, that a specific mitochondrial anti-oxidant treatment (SS-31), or a specific beta-blocker treatment of beta2 adrenergic pathway (ICI-118551 ) or a treatment that stabilizes directly FKBP12- binding RyR1 (S107 ) prevent early disorders of calcium homeostasis and secondary appearance of proteolysis and atrophy induced by mechanical ventilation.Finally, in the last part of my work thesis, I suggest that mitochondrial ROS production may be associated with remodeling of the mitochondrial network with a preponderance of mitochondrial fission phenomenon. This remodeling could be seen as an adaptation of the mitochondria due to a sudden mismatch between energy production and consumption. Indeed, we showed that an inhibitor of the mitochondrial fission (P110), which blocks the connection between the DRP1 protein and its receptor in our animal model of mechanical ventilation, could prevent the appearance of VIDD. Thus the continuity of this last work of my thesis is to make the link between mitochondrial fission and oxidative stress underlying the disorders of calcium homeostasis. Indeed, I hope to show that this treatment during mechanical ventilation, may decrease mitochondrial ROS production, oxidation of RyR1 channel and calcium leak through the RyR1. This last work will emphasis any therapeutic which limit mitochondrial fission and its consequences, to prevent VIDD.Keywords: RyR1, mitochondria, contractile dysfunction, VIDD, oxidative stress
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Weinberg, Jan. "Studies on ventilatory function in chronic neuromuscular disorders /". Stockholm, 1999. http://diss.kib.ki.se/1999/91-628-3936-5/.
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Segura-Castillo, Luis. "Bi-layer diaphragm walls : experimental and numerical analysis". Doctoral thesis, Universitat Politècnica de Catalunya, 2013. http://hdl.handle.net/10803/134771.
Texto completoResumen
Leakage is a widespread problem associated with the construction of diaphragm walls whenever they are erected in water-bearing ground. The aim of the present research is to develop a new type of slurry wall: the bi-layer diaphragm wall (BL), which main objective is to tackle the aforementioned problem. The method to construct it is based on an existing solution: casting a second waterproof concrete layer against the diaphragm walls. In the BL technique, the second layer is made of steel fibre reinforced concrete (SFRC) sprayed over the conventional diaphragm wall (called Mono-Layer diaphragm wall (ML) in this thesis), including a waterproof admixture. The central idea is to maximize the functional attributes of the second layer, allowing it to play a structural role in addition to the waterproofing function.The proposed methodology is based on a combination of experimental works and numerical tools. A design method for the BL walls, which is based on an uncoupled structural-section model, is proposed. The method is later used to carry out different comparisons with ML walls and an exhaustive parametric analysis of the construction processes involved in the walls construction. The experimental campaign comprised test at two levels. At element level, the structural response of walls built in a real building located in Barcelona was studied and, at section level, the bond strength between concretes of cores extracted from the abovementioned walls was measured.The model at structural level, which is based on a finite element model, was contrasted with the results obtained in the experimental walls. The sectional analysis is taken from the specialized literature. With the complete structural-section model, the BL walls are analysed. The study shows that the main flexural resistance is provided by the first layer (the conventional diaphragm wall), providing the SFRC layer a secondary flexural resistance.For the geometrical ranges of the elements considered in the thesis (35 cm to 60 cm width first layer, and 10 cm width second layer) the increase in the cross-section ultimate bending resistance when it is strengthened by the SFRC layer is between 8% and 15%. This increase allows a reduction in the steel reinforcement of the first layer (up to 7.0% of the total flexural reinforcement) and, to some extent, it also collaborates with a displacement reduction (reducing up to 7.3% of the maximum displacements). It was also found that the spraying sequence is a crucial parameter to be able to take advantage of the SFRC collaboration, and specific indications are described.Good concrete to concrete bond strength was obtained for the extracted cores. The average shear strength value measured for each age (2, 6 and 35 days) was always above 1.0 MPa for the different cases. Beyond the local test performed, a monolithic behaviour was observed at element level in the experimental walls.A similar final material consumption was observed between the BL walls and the combined consideration of a ML wall and an external waterproof system. The consideration of the technology cost entails a higher construction cost for the BL technique. However, it is still an interesting option under particular circumstances, like space limitations or if continuous maintenance costs want to be avoided in the future.In general terms it can be said that the research herein presented lay the foundation for the development of the bi-layer diaphragm wall technique, which is a promising solution for the leakage problem of diaphragm walls. Nonetheless, more studies are needed to be able to fully use these types of walls as a standard technique, e.g. a detailed cost study and sustainability analysis, debonding risk, waterproofing capability and above all more full scale experimental cases.Un problema habitual en la construcción de pantallas continuas en terrenos con presencia de agua es la existencia de filtraciones. El objetivo de esta tesis busca resolver este problema mediante el desarrollo de un nuevo tipo de pantalla: la pantalla bi-capa (BL, por sus siglas en inglés). El método para construir estos muros se basa en una solución existente: realizar una segunda capa de hormigón impermeable sobre los muros pantalla. En las pantallas BL, la segunda capa se realiza con hormigón con fibras de acero (SFRC) proyectado sobre las pantallas convencionales (llamadas ML en esta tesis) e incluyendo a su vez una adición impermeabilizante. La idea central es maximizar las funciones de la segunda capa, asignándole un rol estructural, además de la función impermeabilizante. La metodología propuesta se basa en la combinación de trabajos experimentales y herramientas numéricas. Se propone un método de diseño para las pantallas BL basado en modelos estructura-sección desacoplados. Posteriormente se utiliza este método para realizar diferentes comparaciones con pantallas ML y un análisis paramétrico exhaustivo de distintos procesos constructivos involucrados en la construcción de las pantallas BL. La campaña experimental realizada comprende dos niveles: a nivel elemento, se estudió la respuesta estructural de pantallas construidas en un edificio real ubicado en Barcelona; a nivel seccional, se midió el nivel de adherencia entre ambas capas de hormigón mediante testigos extraídos de las pantallas antes mencionadas. El modelo a nivel estructural, basado en elementos finitos, se contrastó con los resultados experimentales obtenidos. El modelo seccional se tomó de la bibliografía estudiada. Con el modelo estructura-sección completo se analizaron las pantallas BL. El estudio muestra que la principal resistencia flexional es aportada por la primera capa (el muro pantalla convencional), siendo secundario el aporte de la capa de SFRC. Para el rango de elementos considerados en esta tesis (35 cm a 60 cm de espesor de primera capa y 10 cm de segunda), el incremento de la resistencia última a flexión cuando se considera el aporte de la capa de SFRC, está entre 8% y 15%. Este incremento permite una reducción en el acero de refuerzo de la primera capa de hasta un 7.0% del total del acero de flexión y, hasta cierto punto, también colabora con una reducción en los desplazamientos (alcanzando reducciones de hasta un 7.3% del desplazamiento máximo). Se observó también que la secuencia de proyección es un factor clave a la hora de aprovechar la colaboración extra aportada por la capa de SFRC. Indicaciones específicas se describen a este respecto. Se obtuvo una buena resistencia de adherencia entre hormigones para los testigos extraídos. La resistencia media medida a cada edad (2, 6, y 35 días) estuvo siempre, para los distintos casos, por encima de 1.0 MPa. Más allá de los ensayos puntuales, se observó un comportamiento monolítico a nivel elemento para las pantallas BL experimentales. Se obtuvo un consumo final de materiales similar entre pantallas BL y la consideración conjunta de una pantalla ML más un sistema impermeabilizante externo. Considerar los costos tecnológicos conlleva un costo constructivo mayor para las pantallas BL. Sin embargo, ésta es aún una opción interesante bajo consideraciones particulares, como limitaciones del espacio subterráneo interior o si se desean evitar costos continuos de mantenimiento. En términos generales, se puede decir que la investigación aquí presentada sienta las bases para el desarrollo de la técnica de muros pantalla bi-capa, la cual es una solución prometedora para el problema de las filtraciones en pantallas. No obstante, son necesarios más estudios para poder usar plenamente este tipo de pantallas de forma habitual, e.g. estudios de sostenibilidad detallados, evaluación del riesgo de desprendimiento de la segunda capa, capacidad impermeable y, sobre todo, más ensayos experimentales a escala real
33
Ward, Michael Edward. "Mechanical, neural and vascular determinants of diaphragm function". Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28549.
Texto completoResumen
The respiratory muscles play a role in respiratory failure when the efficient performance of the work of ventilation and/or their supply of metabolic substrates is disrupted. In this report a model of inspiratory muscle action is presented. The inflationary pressure applied to the lungs and the lung apposed rib cage is partitioned into two parts. One component is attributable to the action of rib cage muscles and the other is due to the interaction between upper and lower rib cage compartments. These contributions were found to be equal.The role of afferent impulses travelling in the phrenic nerve in the control of respiratory muscle activity was investigated by electrical stimulation of its central cut end. Activation of these fibres exerts a non-uniform effect on the activities of the upper airway, rib cage and abdominal muscles and may influence respiratory muscle recruitment.
The roles of blood flow and oxygen delivery in determining diaphragm function was investigated. The rate at which diaphragmatic fatigue develops is diminished at high rates of blood flow and this effect is not related to the associated increase in oxygen delivery. The critical oxygen delivery at which oxygen consumption becomes supply dependent is the same for the resting diaphragm as for the rest of the body tissues. Activation of the diaphragm results in a higher critical oxygen delivery, however, this effect is mitigated by an increase in the critical oxygen extraction ratio.
The role of nitric oxide in regulating diaphragmatic blood flow and oxygen uptake was investigated by infusion of N$ sp{G}$-nitro-L-arginine. This treatment increased diaphragmatic vascular resistance, reduced the duration and magnitude of reactive vasodilation and increased the oxygen consumption and critical extraction ratio in the contracting diaphragm.
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Li, Shing Foon. "On the analysis of singly-propped diaphragm walls". Thesis, King's College London (University of London), 1990. https://kclpure.kcl.ac.uk/portal/en/theses/on-the-analysis-of-singlypropped-diaphragm-walls(a2d84f73-2205-49e9-957e-9ee48b6dd46f).html.
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Kantartzi, Christina. "Ground movements during diaphragm wall installation in clays". Thesis, Queen Mary, University of London, 1993. http://qmro.qmul.ac.uk/xmlui/handle/123456789/1532.
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Diaphragm walls are being used increasingly in connection with building basements and road improvement schemes, particularly in urban areas. Many of these walls retain overconsolidated clay, and the magnitude of the lateral stresses which will act on the wall under service conditions is uncertain. One of the reasons for this is that, although the initial in situ lateral effective earth pressures in an overconsolidated clay deposit will be high, they will be affected to some extent by the process of installation of the wall. Stress relief which occurs during installation should be taken into account, since it will influence the starting point for analysis of the post-construction behaviour. Ground movements which occur during installation are important in their own right, and might for a diaphragmtype retaining wall be more significant than those which occur during and after excavation in front of the wall. The investigation of this problem using a centrifuge modelling technique is the principal aim of the current research. An extensive literature review has been carried out to collate field data concerning the stress history and in situ lateral stresses of overconsolidated clay deposits. These were used to confirm that the proposed centrifuge modelling technique would achieve realistic stress states and changes in stress. A series of centrifuge tests has been carried out at the London Geotechnical Centrifuge Centre (operated jointly by Queen Mary & Westfield College and City University), on samples of overconsolidated speswhite kaolin, simulating the effects of excavation under a slurry trench and concreting the diaphragm wall. The background to the tests, and the geometry and design of the model are discussed. The influence of the groundwater level and panel width on ground movements and changes in pore water pressures during diaphragm wall installation have been investigated, and the results are presented. The centrifuge test results are compared with field data from various sites. The development of a simplified analytical method is presented, which may be used to estimate the installation effects of diaphragm walls in clay. The results of this analysis are compared with the centrifuge test results and field data. Finally, some areas of continuing uncertainty are highlighted and some suggestions for further research are made.
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Langlois, Gilles. "Diaphragm forming : innovation and application to ocean engineering". Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/37530.
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Von, Waldburg Arthur Russell. "Diaphragm control in inflated tool forming of composites". Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/31074.
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Segura, Castillo Luís Emilio. "Bi-layer diaphragm walls : experimental and numerical analysis". Doctoral thesis, Universitat Politècnica de Catalunya, 2013. http://hdl.handle.net/10803/134771.
Texto completoResumen
Tesi per compendi de publicacionsLeakage is a widespread problem associated with the construction of diaphragm walls whenever they are erected in water-bearing ground. The aim of the present research is to develop a new type of slurry wall: the bi-layer diaphragm wall (BL), which main objective is to tackle the aforementioned problem. The method to construct it is based on an existing solution: casting a second waterproof concrete layer against the diaphragm walls. In the BL technique, the second layer is made of steel fibre reinforced concrete (SFRC) sprayed over the conventional diaphragm wall (called Mono-Layer diaphragm wall (ML) in this thesis), including a waterproof admixture. The central idea is to maximize the functional attributes of the second layer, allowing it to play a structural role in addition to the waterproofing function.The proposed methodology is based on a combination of experimental works and numerical tools. A design method for the BL walls, which is based on an uncoupled structural-section model, is proposed. The method is later used to carry out different comparisons with ML walls and an exhaustive parametric analysis of the construction processes involved in the walls construction. The experimental campaign comprised test at two levels. At element level, the structural response of walls built in a real building located in Barcelona was studied and, at section level, the bond strength between concretes of cores extracted from the abovementioned walls was measured.The model at structural level, which is based on a finite element model, was contrasted with the results obtained in the experimental walls. The sectional analysis is taken from the specialized literature. With the complete structural-section model, the BL walls are analysed. The study shows that the main flexural resistance is provided by the first layer (the conventional diaphragm wall), providing the SFRC layer a secondary flexural resistance.For the geometrical ranges of the elements considered in the thesis (35 cm to 60 cm width first layer, and 10 cm width second layer) the increase in the cross-section ultimate bending resistance when it is strengthened by the SFRC layer is between 8% and 15%. This increase allows a reduction in the steel reinforcement of the first layer (up to 7.0% of the total flexural reinforcement) and, to some extent, it also collaborates with a displacement reduction (reducing up to 7.3% of the maximum displacements). It was also found that the spraying sequence is a crucial parameter to be able to take advantage of the SFRC collaboration, and specific indications are described.Good concrete to concrete bond strength was obtained for the extracted cores. The average shear strength value measured for each age (2, 6 and 35 days) was always above 1.0 MPa for the different cases. Beyond the local test performed, a monolithic behaviour was observed at element level in the experimental walls.A similar final material consumption was observed between the BL walls and the combined consideration of a ML wall and an external waterproof system. The consideration of the technology cost entails a higher construction cost for the BL technique. However, it is still an interesting option under particular circumstances, like space limitations or if continuous maintenance costs want to be avoided in the future.In general terms it can be said that the research herein presented lay the foundation for the development of the bi-layer diaphragm wall technique, which is a promising solution for the leakage problem of diaphragm walls. Nonetheless, more studies are needed to be able to fully use these types of walls as a standard technique, e.g. a detailed cost study and sustainability analysis, debonding risk, waterproofing capability and above all more full scale experimental cases.
Un problema habitual en la construcción de pantallas continuas en terrenos con presencia de agua es la existencia de filtraciones. El objetivo de esta tesis busca resolver este problema mediante el desarrollo de un nuevo tipo de pantalla: la pantalla bi-capa (BL, por sus siglas en inglés). El método para construir estos muros se basa en una solución existente: realizar una segunda capa de hormigón impermeable sobre los muros pantalla. En las pantallas BL, la segunda capa se realiza con hormigón con fibras de acero (SFRC) proyectado sobre las pantallas convencionales (llamadas ML en esta tesis) e incluyendo a su vez una adición impermeabilizante. La idea central es maximizar las funciones de la segunda capa, asignándole un rol estructural, además de la función impermeabilizante. La metodología propuesta se basa en la combinación de trabajos experimentales y herramientas numéricas. Se propone un método de diseño para las pantallas BL basado en modelos estructura-sección desacoplados. Posteriormente se utiliza este método para realizar diferentes comparaciones con pantallas ML y un análisis paramétrico exhaustivo de distintos procesos constructivos involucrados en la construcción de las pantallas BL. La campaña experimental realizada comprende dos niveles: a nivel elemento, se estudió la respuesta estructural de pantallas construidas en un edificio real ubicado en Barcelona; a nivel seccional, se midió el nivel de adherencia entre ambas capas de hormigón mediante testigos extraídos de las pantallas antes mencionadas. El modelo a nivel estructural, basado en elementos finitos, se contrastó con los resultados experimentales obtenidos. El modelo seccional se tomó de la bibliografía estudiada. Con el modelo estructura-sección completo se analizaron las pantallas BL. El estudio muestra que la principal resistencia flexional es aportada por la primera capa (el muro pantalla convencional), siendo secundario el aporte de la capa de SFRC. Para el rango de elementos considerados en esta tesis (35 cm a 60 cm de espesor de primera capa y 10 cm de segunda), el incremento de la resistencia última a flexión cuando se considera el aporte de la capa de SFRC, está entre 8% y 15%. Este incremento permite una reducción en el acero de refuerzo de la primera capa de hasta un 7.0% del total del acero de flexión y, hasta cierto punto, también colabora con una reducción en los desplazamientos (alcanzando reducciones de hasta un 7.3% del desplazamiento máximo). Se observó también que la secuencia de proyección es un factor clave a la hora de aprovechar la colaboración extra aportada por la capa de SFRC. Indicaciones específicas se describen a este respecto. Se obtuvo una buena resistencia de adherencia entre hormigones para los testigos extraídos. La resistencia media medida a cada edad (2, 6, y 35 días) estuvo siempre, para los distintos casos, por encima de 1.0 MPa. Más allá de los ensayos puntuales, se observó un comportamiento monolítico a nivel elemento para las pantallas BL experimentales. Se obtuvo un consumo final de materiales similar entre pantallas BL y la consideración conjunta de una pantalla ML más un sistema impermeabilizante externo. Considerar los costos tecnológicos conlleva un costo constructivo mayor para las pantallas BL. Sin embargo, ésta es aún una opción interesante bajo consideraciones particulares, como limitaciones del espacio subterráneo interior o si se desean evitar costos continuos de mantenimiento. En términos generales, se puede decir que la investigación aquí presentada sienta las bases para el desarrollo de la técnica de muros pantalla bi-capa, la cual es una solución prometedora para el problema de las filtraciones en pantallas. No obstante, son necesarios más estudios para poder usar plenamente este tipo de pantallas de forma habitual, e.g. estudios de sostenibilidad detallados, evaluación del riesgo de desprendimiento de la segunda capa, capacidad impermeable y, sobre todo, más ensayos experimentales a escala real
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Kabwe, Aime Mume. "Non-Newtonian loss coefficients for Saunders diaphragm valves". Thesis, Cape Peninsula University of Technology, 2009. http://hdl.handle.net/20.500.11838/914.
Texto completoResumen
Dissertation submitted in fulfilment of requirements for the degree
Master Technology: Chemical Engineering
in the FACULTY OF ENGINEERING
at the CAPE PENINSULA UNIVERSITY OF TECHNOLOGY, 2009The prediction of the energy losses when designing pipeline and pumping systems requires accurate loss coefficient data. But the loss coefficient data found in the open literature was not adequate for predicting the loss coefficient for Saunders straight-through diaphragm valves. As more accurate loss coefficient data to enable more efficient pipeline designs are scarce in the open literature, it is problematic to predict the head loss due to the pipeline fittings, and particularly for diaphragm valves. Most of the data given in the literature are for turbulent flow based on water. Due to water shortages mining operations are forced to increase their solids concentrations and to operate in laminar flow (Slatter, 2002). Consequently there is a need to determine loss coefficient data in laminar flow for valves used in these industries to ensure energy efficient designs (Pienaar et al., 2001; 2004) or if needed, to derive a new correlation to predict losses through Saunders diaphragm valves. However, a systematic study of various sizes of diaphragm valves of different manufacturers to ascertain, if the same loss coefficient can be applied, has never been done. Therefore a comparison will be made between the data produced in this work and the existing correlations. The objective of this research was to determine loss coefficient data in laminar, transitional and turbulent flow for the Saunders type straight-through diaphragm valves ranging from 40 mm to 100 mm in the fully open, 75 %, 50 % and 25 % open positions, using a range of Newtonian and non-Newtonian fluids. The test work was conducted on the valve test rig in the Flow Process Research Centre at the Cape Peninsula University of Technology. This work investigated only Newtonian and time independent homogeneous non-Newtonian fluids or slurries flowing through Saunders straight-through diaphragm valves in the turbulent, transitional and laminar regimes. Weir-type Saunders valves and time-dependent fluid behaviour were not investigated in this study. Preamble Non-Newtonian Loss Coefficients for Saunders Diaphragm Valves A Mume Kabwe The results for each test are presented in the form of valve loss coefficient (kvalve) against Reynolds number (Re). This thesis adds new loss coefficient data to the open literature, and a new correlation, which will be useful for designing pipelines in industries, as well as contributing to the academic debate in this discipline.
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Mbiya, Baudouin Mulumba. "Predicting pressure losses in straight-through diaphragm valves". Thesis, Cape Peninsula University of Technology, 2007. http://hdl.handle.net/20.500.11838/2168.
Texto completoResumen
Thesis (DTech (Civil Engineering))--Cape Peninsula University of Technology, 2007The diaphragm valve traces its origins to ancient Roman and Greek times, where it was used to control water flow and temperature of hot baths (Century-Instruments, 2007). The particularity of this type of valve is the presence of a diaphragm or membrane which controls the flow. Over the years, the design of this type of valve has evolved into two major varieties. The first is the "weir" type, more suitable for less viscous fluids and a second is the "straight-through" type, suitable for suspensions. This study is focused on the straight-through. With the widespread use of such valves in the mining and mineral processing operations and other industrial applications, although there has been improvement in the selection of the diaphragms and body materials of the valves, as well as actuation methods, improvements were not accompanied by thorough hydraulic investigation to determine the method of calculating the additional head loss caused by the presence of diaphragm valves in pipelines, and in particular for the laminar flow of non-Newtonian fluids. The limited correlations available, such as Hooper's (1981), Perry's (1997) and Miller's (1990) are valid only for Newtonian fluids. Furthermore they are classified as Class 3 (Miller, 1990) which means they are not corroborated in other independent studies. BM
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Schmit, Brian David. "Electrical activation of the diaphragm using epimysial electrodes". Case Western Reserve University School of Graduate Studies / OhioLINK, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=case1062594358.
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Kabwe, Aime Mume. "Non-newtonian loss coefficient for Saunders diaphragm valves /". [S.l. : s.n.], 2009. http://dk.cput.ac.za/cgi/viewcontent.cgi?article=1008&context=td_cput.
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Oguoma, Onywuchi N. "Analysis and procedures for design of diaphragm chucks". Thesis, Loughborough University, 1985. https://dspace.lboro.ac.uk/2134/25513.
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In modern automated manufacturing systems, there is a need for work-holding devices that provide for precision, accuracy, reliability, flexibility and remoteness of control. One of such devices is the diaphragm chuck which utilizes the strain energy of its varying thickness diaphragm plate for gripping action. The jaw-carrying diaphragm plate is deflected by a thrust load, and the jaws are bored or ground to the nominal diameter of the workpiece. Gripping action occurs when the workpiece is inserted into the jaws and the thrust is relieved. Designers and manufacturers of diaphragm chucks have in the past been limited to the use of empirical data for diaphragm chuck design. This design limitation has been caused by complex problems due to factors such as the varying thickness encastre diaphragm plate, the gripping couples and the stiffening effects of the jaw slides. This work involved the establishment, by theory and experimental verification, of the design and performance parameters of a diaphragm chuck, and the provision of diaphragm chuck design methodology. The designer is therefore able to achieve the a priori design of the diaphragm chuck. In addition, the user is able to adapt existing diaphragm plates to achieve required gripping forces within existing constraints. The scope of this research is the static gripping action for any number of symmetric jaws. The design method is for diaphragm plates with small thickness taper, and carry detachable jaw slides. The concept of the equivalent constant thickness is applied to the diaphragm plate. Gripping action is divided into two major phases - the separate deflections of the diaphragm plate by a thrust load and symmetric couples. These deflections are equated to obtain the gripping force. This research concludes that the gripping force of a diaphragm chuck is closely predicted by the equivalent constant thickness method. Design data and methodology are provided for diaphragm chuck design. Thus, a designer can now design a diaphragm chuck based on a desired and pre-specified gripping force requirement.
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Hamilton, Kent Anthony. "Improvements to the Design of a Flexible Diaphragm for use in Pressure Wave Generators for Cryogenic Refrigeration Systems". Thesis, University of Canterbury. Mechanical Engineering, 2013. http://hdl.handle.net/10092/7950.
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Low cost cryocoolers suitable for long term use in industrial environments are required for superconducting technologies to be competitive with copper based devices in real world applications. Industrial Research Limited is developing such cryocoolers, which use metal diaphragm based pressure wave generators to convert electrical energy to the gas volume displacement required. This project explores methods of increasing the volume displacement provided by the diaphragms while ensuring the components stay within the acceptable material limits.
Various alternative diaphragm shapes are tested against the currently used shape through finite element analysis. In addition to testing alternative diaphragm shapes, each shape’s dimensions are optimised. It is concluded the currently used design can be improved by offsetting the piston rest position and slightly reducing the piston diameter.
A more detailed analysis is carried out of the bend radii created during fabrication of the diaphragm, and physical testing is performed to verify unexpected calculated stress concentrations. High stresses are observed, however it is concluded unmodelled material features have a large effect on the final stress distribution.
It is recommended advantageous shape changes calculated in the first part of the work be trialled to increase the efficiency of the cryocooler, and that investigation of the material behaviour during commissioning of the pressure wave generator be carried out to better understand the operational limits of the diaphragms.
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Yarber, Caroline Nicole. "Experimental Determination of the Stiffness and Strength of Continuity Tie Connections in Large Wood Roof Dipahragms, and Impact on the Collective Chord Model". DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/846.
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The goal of this thesis is to determine whether continuity ties in large wood diaphragms are stiff enough to engage and provide diaphragm flexural stiffness in a collective chord model. Four series of continuity tie assemblies using Simpson Strong-Tie steel connectors were tested to determine the stiffness of each assembly. The results found from testing were applied to an example building and then analyzed using both the traditional chord method and the collective chord method.
The completed analysis on a typical size warehouse building showed that the collective chord model will act inadvertently on an existing building designed with a traditional chord, or alternatively will potentially act intentionally in the design of a new building. The relative stiffness of the continuity ties will determine if they engage and allow them to act collectively. The testing and analysis completed creates a basis for further research into the actual static and dynamic behavior of these diaphragms. The collective chord model does seem to be a reasonable approximation for how diaphragms actually behave. If more research is conducted into different shaped and sized buildings to confirm that the collective chord model will work on most buildings then it will be a more accurate way to design new diaphragms and analyze existing diaphragms than the current traditional model.
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Lau, Siu Kei. "Fully coupled numerical analysis of a diaphragm wall construction". Thesis, University of Macau, 2009. http://umaclib3.umac.mo/record=b2099635.
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Wong, Sio Leong. "Field monitoring of a diaphragm wall construction in Macau". Thesis, University of Macau, 2009. http://umaclib3.umac.mo/record=b2099642.
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Paquette, Jocelyn. "Seismic testing of unreinforced masonry building with flexible diaphragm". Thesis, University of Ottawa (Canada), 2002. http://hdl.handle.net/10393/6314.
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Appendix 1 of the Uniform Code for Building Conservation (UCBC) presents a systematic procedure for the evaluation and seismic strengthening of unreinforced masonry (URM) bearing wall buildings having flexible diaphragms. However, even though this procedure is founded on extensive component testing, full scale testing of an entire 3-D building having wood diaphragms has not been conducted. Such a test would complement the computer simulations and small-scale shake table tests done by other researchers. For those reasons, a full-scale one-story unreinforced brick masonry specimen having a wood diaphragm was subjected to earthquake excitations using pseudo-dynamic testing. The specimen was designed to better understand the flexible-floor/rigid-wall interaction, the impact of wall continuity at the building corners and the effect of a relatively weak diaphragm on the expected seismic behavior. The unreinforced masonry walls of this building were also repaired with fiberglass materials and re-tested. The dynamic response of the shear walls with piers having a rocking and/or a sliding behavior is analyzed, as well as the response of the wood diaphragm and its interaction with the shear wails. These results are compared with predictions from existing seismic evaluation methodologies and demonstrate how fiberglass strips can be used to improve the rocking behavior. Furthermore, for masonry walls subjected to out-of-plane seismic forces, while it is required to anchor the wall at every floor as a minimum, questions arise as to whether it is also necessary to retrofit the walls between floors. Notably for the facade of many older (circa 1900) residential buildings in North America in which a single wythe exterior masonry wall was tied only with nails to the timber structure, leaving an irregular gap between the masonry and timber walls. To partly answer these questions, three specimens were extracted from an existing building, and were tested using a shake table, submitting them to multiple ground motions of progressively larger intensity until structural failure. Different retrofit methods to increase out-of-plane stiffness and strength were investigated, and various analytical procedures to explain the observed behavior are discussed.
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Gauthier, Alain P. "Structure and function of the fresh and fatigued diaphragm". Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41596.
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This thesis examines the importance of the length-force relationship and the three-dimensional shape of the diaphragm with regard to its inspiratory function. As well as it reports on the manner in which fatigue and aminophylline affect the length-force properties of the diaphragm. First, I studied the effect of fatigue on diaphragm contractility as a function of sarcomere length using an in vitro rat diaphragm strips. Results indicated that fatigue resulted in disproportionately greater reduction of tetanic force at short sarcomere lengths. Second, I reconstructed the three-dimensional shape of the diaphragm to determine if in vitro results are physiologically relevant in humans. I estimated the changes in fibre length and shape that occurs with lung inflation from residual volume to total lung capacity in normal subjects. Results suggested that the inspiratory function of the human diaphragm can be entirely attributed to its length-force relationship rather than changes in shape under conditions of twitch phrenic nerve stimulations. Finally, I confirmed that fatigue caused a greater percent reduction of transdiaphragmatic pressure at high lung volume in response to single supramaximal shocks delivered bilaterally to the phrenic nerves at high lung volume; and demonstrated that aminophylline potentiated human diaphragm contractility more at high than at low lung volumes, both under fresh and fatigue conditions. I propose an explanation for the effect of fatigue and aminophylline on diaphragm contractility at different sarcomere lengths based on known actions of these factors and muscle shortening on excitation-contraction coupling mechanisms of skeletal muscles.
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Sharshar, Tarek. "Cortical control of the diaphragm : insights from transcranial stimulation". Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417110.
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