No description available.

The aspiration of oral and gastric substances is a well-known risk for ventilator associated pneumonia (VAP) in the intubated, mechanically ventilated (MV), patient of the intensive care unit (ICU) population. The gastric biomarker pepsin and the oral biomarker salivary amylase have been identified as evidence of aspiration prior to the manifestation of acute pulmonary illness. In an effort to decrease the risk for aspiration, several evidence based nursing practices are in place. Actions include 30 degree head of the bed positioning, oral care, suctioning, and circuit change interval protocols, as well as the administration of medication with the objective of reducing acid reflux. Additional recommendations concern the type of endotracheal tube (ETT) used to ventilate the intubated patient. The continuous subglottic suctioning endotracheal tube (CSS-ETT) features an additional port which continually suctions secretions that accumulate above the inflated endotracheal cuff. Patients with standard endotracheal tubes (S-ETT) receive manual, as needed suctioning of accumulated secretions in the mouth and the oropharynx per agency protocol. Research of the critical care population has demonstrated a decreased instance of VAP using CSS-ETT as compared to S-ETT utilization. This study sought to compare the incidence of the biomarkers pepsin and salivary amylase in the suctioned oral and tracheal secretions of patients with S-ETT compared to patients with CSS-ETT. Part of the protocol of a descriptive, comparative study of the clinical indicators for suctioning established the collection of the paired suctioned oral and tracheal aspirates. Those collected aspirates were analyzed for a pilot study of pepsin and amylase analysis. This study compares the incidence of aspirates in oral and tracheal secretions by endotracheal tube type.; The intention of this study was that it would assist in demonstrating beneficial aspects of the selection of the CSS-ETT. It is considered that further investigation with a larger population group could add statistical significance.; Tracheal aspirates were obtained with a closed tracheal suction device while oral secretions were obtained with a suction catheter designed to reach the oropharynx. Biomarkers assayed were the gastric marker pepsin and the oropharyngeal marker salivary amylase. Assays of pepsin and salivary amylase were performed using standard procedures in a specialty diagnostic laboratory. Specimens were obtained from 11 subjects: 8 male and 3 female. The majority were Caucasian (n=9), had a CSS-ETT (n=8), were on mechanical ventilation in the synchronized intermittent mandatory ventilation mode, and on tube feedings (n=9) located in the stomach (n=7). The mean age was 56 years. Feeding tubes were placed in 9 patients, and the majority of the tubes were Dobbhoff. Pepsin was found in the oral secretions of 62.5% (n = 5) of the CSS-ETT subjects, while 50.0% (n = 4) had pepsin in the tracheal aspirate. Pepsin was found in the oral secretions of 66.7% (n = 2) of the S-ETT subjects, and 66.7% (n = 2) had pepsin in their tracheal aspirate. All subjects of both groups (n = 11) had oral salivary amylase detected. Salivary amylase was detected in the tracheal aspirate of 100% (n = 3) of the S-ETT subjects versus 62.5% (n = 5) in CSS-ETT group. Based on the results of this study, there was a reduction in the number of subjects who had oral compared to tracheal aspirate pepsin in the CSS-ETT group (n = 5 oral versus n = 4 tracheal) tube type. The S-ETT group had equal number of subjects with oral (n = 2) and tracheal pepsin detected (n = 2). However, the results when comparing the S-ETT and the CSS-ETT groups were not statistically significant (p = 0.898 pepsin oral and 0.621 tracheal pepsin). There may be clinical significance. It appears that the CSS-ETT was beneficial in that group; two fewer subjects had pepsin in their tracheal aspirate (n = 5 oral versus n = 4 tracheal aspirate pepsin).

The Navy is interested in comparing multi-thermocouple probes, tested in the field, with scanned laser absorption thermometry. This comparison aims to understand the effects of excess Carbon Monoxide (CO) and carbon (soot) resulting from rich nitromethane (CH3NO2) combustion events interacting with the outside air, as well as aluminum catalysts, on the temperature of the ensuing fireball. These interactions create mixing zones with varying gas temperature and composition. Currently, research at the UCF shock tube involves taking preliminary CO-scanned thermometry data with the goal of comparing thermocouple insert results in the future. The thermocouple insert is securely positioned within a specially designed end wall and protected by a heat shield. By comparing the temperature measurements obtained by one-dimensional shock relations with those obtained through scanned laser thermometry, based on CO characterization experiments conducted previously on the same shock tube, we aim to analyze temperature measurements and evaluate how the presence of the thermocouple insert affects the incident shockwave geometry, as well as the resulting reflected wave and temperature conditions. The goal is to observe any discrepancies in temperature measurements between the one-dimensional shock relations and the scanned laser method. This will enable researchers to assess the impact of the thermocouple insert in testing environments. Experiments were conducted using a mixture of 3% carbon monoxide (CO), 20% helium (He), and 77% argon (Ar), with an expected temperature range of 950 – 1950K, at pressures of 0.7 – 1 atmosphere (atm).

No description available.

No description available.

No description available.

An investigation of the dynamic lift on the central tube in square tube arrays is conducted. Three array spacing ratios with P/ D = 3.37, 2.18 and 1.58, corresponding to large, intermediate and small spacing ratios are investigated. These three classes exhibit specific flow characteristics and distinct behavior during acoustic resonance. The aim of the present investigation is to determine the effect of the acoustic pressure field and its contribution to dynamic lift during acoustic resonance. During acoustic resonance there are two sources of dynamic lift. One source is provided by the sound field. The standing wave excited during resonance causes dynamic lift from the acoustic pressure distribution on the surface of the cylinder. In the absence of flow, loud speakers are used to excite the first transverse acoustic mode over a range of sound pressure levels, effectively determining the relationship between the resultant dynamic lift and sound pressure level of the acoustic standing wave. The dynamic lift due to the sound field is well predicted by numerical simulation of the acoustic pressure distribution in the tube array. Using the validated numerical simulation it is possible to extend the results to a large range of cylinder diameter to wavelength ratios. The other source of dynamic lift is provided by the periodic flow though the tube array, known as vortex shedding, which is enhanced during resonance. The total dynamic lift is dependant on the phase shift between the sound field and aerodynamic lift components. For small and intermediate tube arrays, acoustic resonance occurs before coincidence of the natural vortex shedding frequency and the acoustic mode. For the large tube array, frequency coincidence occurs within the resonance range. The phase shift between the dynamic lift due to sound and that due to the aerodynamic lift is small for the pre-coincidence resonance range observed for small and intermediate tube arrays and therefore the total dynamic lift is well predicted by the sum of the magnitudes of the dynamic lift due to the sound field and aerodynamic lift components caused by vortex shedding. Past the frequency of coincidence, a phase jump occurs in the aerodynamic lift causing a large phase shift between the sound field and aerodynamic lift components in the large spacing ratio array. The summation of the aerodynamic lift and the lift due to the sound field over predicts the total dynamic lift measured during acoustic resonance in this case. The present results are used to develop a conservative guideline for estimating the total dynamic lift during acoustic resonance. / Thesis / Master of Applied Science (MASc)

Rhythmic collapse and reinflation of tracheal tubes is a form of active ventilation that augments convective gas exchange in multiple orders of insects. The underlying mechanism driving this phenomenon is not known. Among other things, tracheal tube collapse could be caused by either direct impingement of trachea or by a difference of pressure gradients between the intra-tracheal air and the surrounding hemolymph. To determine the relationship between hemolymph pressure and tracheal tube collapse in the ground beetle (Pterostichus commutabulis), we performed direct measurements of hemolymph pressure inside the beetle's prothorax while simultaneously using synchrotron phase contrast imaging to observe morphological changes in the trachea. We observed that a pressure pulse co-occurred with every tube compression observed throughout the body, suggesting that pulses in hemolymph pressure are responsible for tracheal collapse. To assess the effects of the experimental x-ray conditions imposed on the subjects during imaging, hemolymph pressure was also directly measured in the prothorax of beetles less restricted in non-x-ray trials. To compare the pressure patterns in the two experiments, a novel method of identifying and analyzing pressure pulses was developed and applied to the data sets. The comparison provides the first quantitative characterization of a directly measured hemolymph pressure environment, and demonstrates strong similarities in the pressure patterns recorded in both tests. However, pulses occurring during the x-ray experiments exhibited larger average magnitudes. Further video analysis however shows that collapse of the primary tracheal tubes was observed to occur even in the presence of the smallest simultaneously measured pressure pulse (1.01 kPa), suggesting that collapse of the primary tracheal tubes. / Master of Science

Compact heat exchangers are usually characterized by a large heat transfer surface per unit of volume. These characteristics are useful when thermal energy between two or more fluids must be exchanged without mixing. Most compact heat exchangers are liquid-to-air heat exchangers, with approximately 85% of the total thermal resistance occurring on the air side of the heat exchanger. To reduce the space and weight of a compact heat exchanger, augmentation strategies must be proposed to reduce the air side resistance. However, before any strategies to augment the air side heat transfer can be proposed, a thorough insight of the current mechanisms that govern air side heat transfer is required. The tube wall heat transfer results presented in this paper were obtained both experimentally and computationally for a typical compact heat exchanger design. Both isothermal and constant heat flux tube walls were studied. For the experimental investigation, a scaled-up model of the louvered fin-tube wall was tested in a flow facility. Although computational results for the isothermal tube wall are shown, control of the experimental isothermal tube wall proved to be unrealistic and only heat transfer measurements along the constant heat flux tube wall were made. For the constant heat flux tube wall, reasonable agreement has been achieved between the measurements and the steady, three-dimensional computational predictions. The results of the study showed that high heat transfer coefficients existed at the entrance to the louver array as well as in the louver reversal region. Vortices created at the leading edge of the louvers augmented heat transfer by thinning the tube wall boundary layer. Results indicate that an augmentation ratio of up to 3 times can occur for a tube wall of a louvered fin compact heat exchanger as compared to a flat plate. / Master of Science

Daylight penetration into a deep interior space can be achieved by using a light tube strategy. This research investigates how effective a room's ceiling cavity can be as a daylight transporting system. The design, therefore, tries to answer the question "What is the optimal geometry for a ceiling cavity and inlet aperture to bring deeper daylight penetration and achieve a higher illumination level, measured at the back of a room, than that achieved by a typical high window opening?" Corporate affiliate 3M assisted this project by providing a prismatic and highly specular surface to cover the underlying geometry of the ceiling cavity. A 16' deep room section with a high window opening on one side was constructed as a test cell. Inside, sensors were set up to allow light measurement at task level along the depth of the room. Light rays were deflected by the geometry of the ceiling cavity, through a number of internal reflections on the highly reflective film surface, to a diffuser at the back. The three most promising geometric designs from scaled model tests were selected, installed and tested for efficiency in the full-scale test cell. / Master of Science