Degree Not Listed / Department of Clinical Sciences / Warren L. Beard / Recumbency affects respiratory mechanics and oxygenation in anesthetized horses. Changes in pleural and abdominal pressures that can impair ventilation have not been described in all recumbencies. The objective of this study was to determine the effects of patient positioning on transdiaphragmatic pressures and selected hemodynamic variables. Horses were maintained under total intravenous general anesthesia with nasal oxygen supplementation. Trans-nasal balloon catheters connected to pressure transducers placed within the stomach and thoracic esophagus were used to measure intrathoracic and gastric pressure in standing and anesthetized horses positioned in: right and left lateral recumbency, dorsal recumbency, reverse Trendelenburg position, and Trendelenburg position. Transdiaphragmatic pressures were calculated as the difference between gastric and intrathoracic pressure. Measurements of SpO2, heart rate, systolic, diastolic and mean arterial pressure, and respiratory rate were obtained every 5 minutes. When compared to dorsal recumbency, gastric expiratory pressure is decreased in the standing position. Thoracic expiratory pressure is decreased in standing and reverse Trendelenburg. Transdiaphragmatic expiratory pressure and SpO2 are decreased in Trendelenburg. Heart rate is increased in reverse Trendelenburg. Systolic, diastolic, and mean arterial pressures are decreased in reverse Trendelenburg and increased in left lateral and right lateral. We found there is wide variation in respiratory pressures between horses and positions and they are not predictive of associated changes in hemodynamic variables.

The content of this master‘s thesis is a study of diaphragm pump with linear drive. Linear motor was used as the linear drive. Thesis is well – founded by theoretic calculation of pump and its design draft. Likewise, the thesis includes optimalization of suction, or pressure, valve for pump, created by using computer fluid dynamics software. Thesis is complemented by basic view of different types of pumps based on the classification by hydrodynamic and hydrostatic pumps. Subsequently, the preview of blood – flow pumps is presented.

Since the isolation of triiodothyronine (T3) by Pitt-Rivers and Gross (1953) several questions as to its role as a thyroid hormone arose. Does T3 have the same or different actions than that of thyroxine (T4 )? Is T3 an emergency hormone, since its synthesis relative to T4 is greatly increased during periods of low iodine intake and its response time is I/5th that of T4 (Ackerman and Arons, 1958)? Are there any interactions modifying their respective actions?

Lateral forces generated by wind, earthquakes, and other horizontal loads are trans-mitted from the floor diaphragms to the columns and walls that comprise the vertical lateral force resisting system in a building. Strengthening of the diaphragms in older reinforced concrete buildings may be necessary for several reasons, including to enhance seismic performance, address inadequate strength or stiffness, provide missing or incomplete load paths, improve inadequate shear transfer/connection capacity, and to accommodate changes in the use and occupancy of the structure. Engineers are currently using externally bonded fiber reinforced polymer (FRP) composites to retrofit deficient diaphragms. However, this application is beyond the scope of current FRP-related design documents, including ACI PRC-440.2R-17 "Guide for the Design and Construction of Externally bonded FRP Systems for Strengthening Concrete Structures". The lack of consensus around design recommendations for FRP strengthening of diaphragms is problematic and creates uncertainty about which approaches are proven and what are best practice. This thesis summarizes the results from an experimental research program designed to investigate the shear behavior of reinforced concrete diaphragms strengthened using external-ly bonded FRP. Six one-half scale reinforced concrete cantilever diaphragms were tested in shear to evaluate the influence of FRP material, density, spacing, orientation, and intermediate anchorage configuration on the performance of diaphragm strengthening. The specimens were designed to represent the diaphragm shear zone adjacent to a shear wall in a concrete building. The tests were performed using a reverse cyclic displacement protocol representative of earthquake actions. The tests included a baseline unretrofitted concrete specimen, followed by five retrofitted specimens with different configurations of externally bonded FRP. Each retrofitted specimen was designed to maintain a similar FRP axial stiffness while varying the FRP retrofit parameters. The results demonstrated that externally bonded FRP retrofitting improved both the shear strength and stiffness of the strengthened test specimens. All the retrofitted specimens experienced an FRP debonding failure initiated by intermediate shear cracks with the field of the diaphragm, occurring after yielding of the internal steel rebar. The results highlighted that the overall behavior of the specimens was influenced by the way the retrofit schemes were proportioned and detailed. For example, the application of FRP parallel to the direction of applied shear was found to be most effective at increasing the diaphragm strength. Conversely, the application of FRP perpendicular to the applied shear was found to increase the diaphragm ductility. In addition, the shear strength contribution of externally bonded FRP was significantly influenced by the retrofit surface coverage. Compared with narrow strips of high-density fabric, retrofits detailed with less dense fabric spread uniformly over the surface exhibited superior performance due to better control of the shear cracks. Furthermore, no meaningful difference in performance was observed between diaphragms strengthened with glass and carbon FRP composites, provided the retrofits were proportioned to achieve com-parable levels of stiffness. This finding suggests that either type of fabric may be suitable for diaphragm strengthening. Finally, the use of overstrength intermediate FRP anchors did not noticeably affect the FRP shear strength contribution. However, the presence of intermediate anchors led to localized failures that concentrated inelastic diaphragm response between anchor locations, resulting in a significant reduction in diaphragm deformation capacity. The test results were used to develop design recommendations for shear strengthening existing concrete diaphragms using externally bonded FRP. The recommendations included guidance on how to establish the effective FRP design strain and the nominal shear strength contribution of the FRP, both of which tended to be conservative and underestimated the actual behavior observed during the experiments. The recommendations also address the use of intermediate and end FRP anchors, limitations on the clear spacing between sheets, and other factors pertinent to retrofit design. / Master of Science / The floor diaphragm in a reinforced concrete building transmits lateral forces generated by wind, earthquakes, and other horizontal loads to the building's vertical lateral force resisting system. Diaphragms in older reinforced concrete buildings are often retrofitted to meet seismic demands. Retrofitting deficient diaphragms increases infrastructure sustainability by promoting reuse and reconfiguration of existing buildings while mitigating structural deficiencies. Using externally bonded fiber reinforced polymer (FRP) composites is a com-mon strengthening technique often used without supporting guidance or test data. An industry need for diaphragm retrofit provisions, coupled with a substantial lack of data clearly indicates a need for experimental testing of diaphragm elements strengthened with externally bonded FRP. This thesis summarizes the results from an experimental research program designed to investigate the shear behavior of reinforced concrete diaphragms strengthened using externally bonded FRP. Six reinforced concrete diaphragm specimens were tested to study how variations in FRP material, density, spacing, orientation, and anchorage configuration impacted the performance of the retrofit. One specimen served as a control while the five other specimens were retrofitted with various configurations of FRP. The control specimen experienced a diagonal tension shear failure while each FRP strengthened specimen exhibited an FRP debonding failure, which was initiated by intermediate shear cracks occurring within the field of the diaphragm. The experimental results were analyzed to understand how the FRP retro-fits affected the strength, stiffness, ductility, and energy dissipation of each specimen. It was concluded that externally bonded FRP improves the seismic performance of a building by increasing the in-plane shear strength of the diaphragm. Existing design provisions were evaluated and compared to the experimental findings. Design recommendations were formed based on the observed affect of the test variables.

Congenital diaphragmatic hernia (CDH) is a potentially fatal condition found in neonates where embryological defects in the diaphragm negatively impact fetal maturation and growth. The defect allows contents below the diaphragm to potentially migrate into the thoracic cavity during development, which could lead to secondary complication including pulmonary hypertension and left ventricular hypoplasia. CDH tends to have a high neonate mortality rate in congruence with the severity of the condition. Several risk factors for CDH include accompanying chromosomal abnormalities and the anatomical positions of organs in the fetus. Diagnosis is typically found with an ultrasound (US) in utero. There have been several studies in order to better understand the pathology of the disease and new techniques to try and alleviate the cases prenatally, however the risks involved with these procedures may outweigh the benefits. The standard practice for neonates that qualify for postnatal treatment is the use of extracorporeal membrane oxygenation (ECMO) postnatally, to facilitate oxygenated blood to the fetus via a bio-mechanical device. Recent treatment techniques that have revolutionized care for CDH include a delayed surgical intervention in order to reduce the risk of developing a pulmonary ailment such as pulmonary hypertension and/or lung hypoplasia. Interventions with inhaled nitric oxide have also been shown to relegate a similar outcome to those with ECMO intervention. Despite the advancements in knowledge, treatment, and technology, the mortality rate for CDH still hovers around 50% on average, yet that percentage can increase or decrease depending on the severity of the condition and any genetic abnormalities associated with it. Overall, while there have been great strides in treatment and understanding of CDH, additional research is necessary in order to provide the utmost care for future generations of CDH patients.

The validity of the dynamic analysis based on simplified plate model was investigated using of FE-codes ANSYS in the present paper. The simplified clamped multi-layered plate model was first verified by comparison with the exact model. The simply supported plate model was confirmed to be not a suitable model due to its large error as comparing with exact model. Influence of dimensions of laminar diaphragm on nature frequencies was studied. Deflection and voltage response driven by mechanical and electric loads were described. The optimized thickness ratio of PZT layer to SiO₂ and Si layers was given in the paper to obtain the best deflection export of actuator in design. / Singapore-MIT Alliance (SMA)

The primary objective of the dissertation research is to establish the seismic demands of precast concrete floor diaphragms designed with an emerging design methodology. To accomplish this, three-dimensional (3D) finite element (FE) models of diaphragm-sensitive precast concrete structures have been developed by extending two-dimensional (2D) diaphragm model developed previously for nonlinear static "pushover" analyses. Using these models, diaphragm seismic demands under expected hazard are evaluated through the nonlinear transient dynamic analyses (NLTDA).The research work is composed of four major parts:(1) Developing 3D NLTDA analytical model for diaphragm-sensitive precast concrete structures: The 3D structure model is extended from a 2D FE diaphragm model developed by a previous researcher. This process involves properly handling comparability conditions in 3D, incorporating proper hysteresis behavior for the diaphragm reinforcement, and developing appropriate lateral force resisting system (LFRS) models. A sensitivity analysis is performed for 3D NLTDA modeling to assist in creating an appropriate model.(2) Application of the model in integrated analysis-driven physical testing: These experiments occurred at Lehigh University (LU) with project collaborators. The loading in these tests were controlled by NLTDA of the 3D analytical model. The tests were used to examine the seismic response of key joints (critical flexure and shear joints) in the diaphragm under realistic demands and to further calibrate the analytical model.(3) Analytical modeling in support of shake table testing: The shake table test was performed at University of California San Diego (UCSD). The test involved a half scale three-story diaphragm-sensitive precast concrete structure. NLTDA using the 3D analytical model is used to assist in design and performance prediction of the test specimen. The test results are being used to calibrate/verify the analytical model.(4) Calibrating design factors for the emerging diaphragm design methodology: In the last research step, the 3D analytical model is used to calibrate trial design factors for the emerging diaphragm design methodology. These factors are established based on a parametric study of NLDTA at different seismic hazard levels using simple structure configurations. These factors will be evaluated on models of realistic structures to determine design factors for the final design procedure.

Over the past fifty years, many states have recognized the benefits of making precast, prestressed multi-girder bridges continuous by connecting the girders with a continuity diaphragm. Although there is widespread agreement on the benefits of continuous construction, there has not been as much agreement on either the methods used for design of these systems or the details used for the continuity connections. To aid designers in choosing the most appropriate method, an analytical and experimental study was undertaken at Virginia Tech. Analyses were done to compare the differences in the predicted continuity moments for different design methods and assumptions over a range of commonly used systems of Precast Concrete Bulb Tee (PCBT) girders and cast-in-place slabs. The results of the analyses were used to develop three continuity connection details for testing during the experimental study. Three different continuity connections were tested using full depth PCBT 45 in. deep girders made continuous with a 6 ft wide slab. The bottom of the ends of the girders were made continuous with the continuity connection by extending prestressing strands for one test and extending 180 degree bent bars for the other test. Both connections adequately resisted service, cyclic, and ultimate loads. But, the test with the extended bars remained stiffer during cyclic loading and is recommended for use. A third test was performed on a system using only a slab cast across the top of the girders. Two primary cracks formed above the ends of the girders at the joint during service testing, after which no significant increase in damage took place. Results from the analytical study indicate that the predicted positive thermal restraint moments may be significant, similar in magnitude to the actual positive cracking moment capacities. Results from the experimental study indicate that restraint moments develop early due to thermal expansion of the deck during curing and subsequent differential shrinkage; however, the magnitudes of the early age restraint moments are much less than conventional analyses predict. / Ph. D.

Several rubber diaphragms, of the same type used inside an hydraulic accumulator, failed a short time after they were mounted. While there is nothing special with these failures the cost, in some cases can be high. A closer look, at the damaged diaphragms reveal an interesting nonsymmetric radial deformation accompanied in some cases by cracks. Most of the analyses regarding the failures of rubber diaphragms offer explanations only from a chemical or material science point of view. We propose in this thesis a new perspective from a mechanical-structural engineering view. Therefore the main goal of the thesis is to investigate the deformation of a diaphragm and based on this analysis to propose an explanation for formation of the cracks. It is shown that the analysis of the diaphragm problem leads to a pseudo-nonconservative system and involves a buckling, a post buckling (dynamic snap-through), an eversion, and a load response analysis. The problem is approached numerically using the nite element method. The character of pseudo-nonconservativeness of the system requires, in this case, an update of the tangent stiffness matrix with a certain stiffness correction. This new correction is proposed also. The result is valid not only for this particular problem but for the entire class of problems to which the diaphragm belongs. This correction is implemented in an existing nite element program (NIKE3D) and used to analyze the diaphragm deformation. The results indicate that under the typical load condition for a diaphragm a certain deformation pattern occurs, and this can lead to the formation of cracks. This deformation matches extremely well with the actual deformed shape of a typical failed diaphragm. It is shown that the deformation pattern depends on the structural properties of the diaphragm rather than on the magnitude of the applied load. The nonsymmetry in the diaphragm deformation and the difference in the crack development is explained also. / Ph. D.

This research document focuses on prestressed PCBT girders made composite with a cast-in-place concrete deck and continuous over several spans through the use of continuity diaphragms. The current design procedure in AASHTO states that a continuity diaphragm is considered to be fully effective if a compressive stress develops in the bottom of the diaphragm when the superimposed permanent load, settlement, creep, shrinkage, 50 percent live load, and temperature gradient are summed, or if the girders are stored at least 90 days when continuity is established. It is more economical to store girders for fewer days, so it is important to know the minimum number of days that girders must be stored to satisfy AASHTO requirements. In 2005, Charles Newhouse developed the positive moment diaphragm reinforcement detail that is currently being adopted by VDOT. This thesis concludes that Newhouse's detail, four No. 6 bars bent 180° and extended into the diaphragm, is adequate for all girders except for the PCBT-77, PCBT-85, and the PCBT-93 when the girders are stored for a minimum of 90 days. It is recommended that two additional bent strands be extended into the continuity diaphragm for these three girder sizes. It was also concluded that about half of the cases result in a significant reduction in the minimum number of storage days if the designer is willing to perform a detailed analysis. The other half of the cases must be stored for 90 days because the total moment in the diaphragm will never become negative and satisfy the AASHTO requirement. In general, narrower girder spacing and higher concrete compressive strength results in shorter required storage duration. The PCA Method was used in this analysis with the updated AASHTO LRFD creep, shrinkage, and prestress loss models. A recommended quick check is to sum the thermal, composite dead load, and half of the live load restraint moments. The girder must be stored 90 days if that sum is positive, and a more detailed time-dependent analysis would result in a shorter than 90 day storage period if that sum is negative. / Master of Science