11-20 of 30 results
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An Exploratory Study of General Aviation Visual to Instrument Meteorological Condition Contextual Factors
PI James Hartman
CO-I Mark Friend
The purpose of this dissertation was to bridge the existing literature gap of outdated contextual factor (CF) research through examination and determination of current General Aviation (GA) Title 14 Code of Federal Regulations (CFR) Part 91 visual flight rules (VFR)-into-instrument meteorological condition (IMC) contextual factors. Contextual factors are a multifaceted arrangement of pertinent events or occurrences contributing to pilot accidents in weather-related decision-making errors.
A total of 46 contextual factors were identified and examined from the reviewed research literature. The study examined and determined the presence of the 46 contextual factors, frequencies, and manifestations in the GA VFR-into-IMC Aviation Accident Reports (AARs) archived in the National Transportation Safety Board (NTSB) online safety database. Significant relationships were identified among the contextual factors and pilot age, flight experience, weather, flight conditions, time of day, and certification level using point biserial and phi correlations. Contextual factor significant effects on the crash distance from departure and crash distance from the planned destination were revealed using multiple regression. A qualitative methodology was used on secondary data. Three subject matter experts (SMEs) for the main study analyzed a sample of 85 accidents for the presence of the 46 contextual factors. Raters then reported the presence of the contextual factors and provided opinions on how the contextual factors were manifested. Qualitative analysis revealed the presence of 37 out of 46 contextual factors. Highest frequency factors included number of passengers on board (CF29), accident time of day (CF1), crash distance from the planned destination (CF15), not filing of a flight plan (CF21), and underestimating risk (CF43). Raters described numerous manifestations of the contextual factors including 62% of the accident flights had passengers on board the aircraft (CF29). Quantitative analysis discovered several significantly weak to moderate relationships among pilot age, flight experience, weather, flight conditions, time of day, certification level, and the contextual factors. Several contextual factors had significant effects on the crash distance from departure and crash distance from the planned destination. Findings indicated the contextual factors were extensive in GA accidents. Additional research should focus on all flight domains, including further study of GA Part 91 VFR-into-IMC accidents. It is recommended the GA Part 91 pilot community be trained on the contextual factors assessed.
Categories: Graduate
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An Investigation of Factors that Influence Passengers’ Intentions to Use Biometric Technologies at Airports
PI Kabir Kasim
CO-I Scott Winter
This research investigated the factors that influence passengers’ intentions to choose the use of biometrics over other methods of identification. The current study utilized a quantitative research method via an online survey of 689 persons from Amazon ® Mechanical Turk ® (MTurk) and employed structural equation modeling (SEM) techniques for data analysis. The study utilized the theory of planned behavior (TPB) as the grounded theory, while perceived usefulness and perceived ease of use were included as additional factors that could influence individuals’ intentions to use new technology.
The study further assessed the impact of passengers’ privacy concerns on the intentions to use biometrics and investigated how the privacy concerns moderate the influencing factors of passengers’ behavioral intentions. Because of the coronavirus (COVID-19) pandemic that became prevalent at the time of the study, a COVID-19 variable was introduced as a control variable to examine if there were any effects of COVID-19 on passengers' behavioral intentions while controlling for the other variables.
Results showed that for the TPB factors, attitudes and subjective norms significantly influenced passengers’ behavioral intentions to use biometrics, while the effect of perceived behavioral control (PBC) on passengers’ intentions was not significant. The additional factors of perceived usefulness and perceived ease of use did not significantly influence passengers’ intentions. In addition, the hypothesized relationships between privacy concerns and four factors, behavioral intentions, attitudes, PBC, and perceived ease of use were supported, while the relationships between privacy concerns and perceived usefulness and between privacy concerns and subjective norms were not supported.
The examination of the moderating effects found that privacy concerns moderated the relationships between passengers’ intentions and three factors: attitudes, subjective norms, and perceived usefulness. However, because the interaction plots showed that the moderating effects were weak, the effects were not considered to be of much value and were therefore not added to the final model. Results also showed that the control variable (COVID-19) did not significantly influence passengers’ behavioral intentions and passengers’ privacy concerns while controlling for the other variables.
Practically, the study contributed a research model and specified factors that were postulated to influence passengers’ behavioral intentions to use biometrics at airports. Further research would be required to determine additional factors that influence behavioral intentions. Finally, although the moderating effects were not used in the final model, the findings suggest that stakeholders can customize biometric systems and solutions appropriately to cater to passengers’ concerns.
Categories: Graduate
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The Effects of Carry-on Baggage on Aircraft Evacuation Efficiency
PI Sang-A Lee
Overall, two studies were conducted to provide an outline of the factors that affect and affected by carry-on baggage. Study 1 used an agent-based model, AnyLogic, to simulate the aircraft evacuation model of an A380. The model was validated, and a two-way Analysis of Variance (ANOVA) was conducted to examine the effects of the percentage of passengers evacuating with carry-on baggage and exit selection choices on the total evacuation time. The simulation results suggested that the mean evacuation time for 0% was significantly lower than 50% and 80%. The mean evacuation time for the shortest queue choice was also lower than the closest exit choice. Study 2 used an expanded theory of planned behavior (TPB) to determine the factors that affect passengers’ intentions to evacuate with carry-on baggage. The confirmatory factor analysis (CFA) and structural equation model (SEM) were used to analyze the data. The results indicated that attitude was the significant determinant of passengers’ intention to evacuate with carry-on baggage.
The most frequent obstacle of an aircraft evacuation is the passengers carrying baggage while evacuating. Passengers who insist on taking their carry-on baggage during an emergency evacuation not only slow down the evacuation process but also act as a significant risk to the safety of other passengers. This study investigated the factors that affect passengers’ behavioral intention to evacuate with carry-on baggage and the effects of evacuating with carry-on baggage on the total evacuation time. Overall, two studies were conducted to provide an outline of the factors that affect and affected by carry-on baggage.
Study 1 used an agent-based model, AnyLogic, to simulate the aircraft evacuation model of an A380. The model was validated, and a two-way Analysis of Variance (ANOVA) was conducted to examine the effects of the percentage of passengers evacuating with carry-on baggage and exit selection choices on the total evacuation time. The simulation results suggested that the mean evacuation time for 0% was significantly lower than 50% and 80%. The mean evacuation time for the shortest queue choice was also lower than the closest exit choice.
Study 2 used an expanded theory of planned behavior (TPB) to determine the factors that affect passengers’ intentions to evacuate with carry-on baggage. The total v sample size was 281 after data cleaning. The confirmatory factor analysis (CFA) and structural equation model (SEM) were used to analyze the data. The results indicated that attitude was the significant determinant of passengers’ intention to evacuate with carry-on baggage. The factor of ‘perceived risk’ was not supported, but the results showed that the opposite effect of the hypothesis was significant. The results of this study fill a gap in the research regarding passengers’ behavior of evacuating with carry-on baggage. Potential applications of this study will also help the federal regulations, airlines, and aircraft manufacturers by providing a better understanding of carry-on baggage at aircraft emergency.
Categories: Graduate
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The impact of corporate social responsibility communication on corporate reputation
PI Doreen McGunagle
CO-I Dixie Button
The goal of this research project is to analyze the ethics of social media used by U.S. airlines. In particular, how the four major carriers, Southwest Airlines, Delta, United, and American Airlines Group, stack up against each other in terms of privacy and the ethical use of information obtained via social media sites such as Facebook.
Corporate social responsibility (CSR) is increasingly more important for firms in today’s global marketplace and effective communication of CSR initiatives is vital toward enhancing a company’s reputation and its sales revenues. With this consideration, the reputations of firms in the Aerospace and Defense (A & D) industry worldwide, in conjunction with their use of social media were examined to validate a link between the use of social media to communicate CSR activities and a firm’s reputation ranking.
Methodology involved a qualitative content analysis of the online and social media presence of the top 20 A & D companies from the Deloitte Toche Tohmatso Limited (DTTL) 2014 Global A & D financial performance study. Data from six indicators of CSR: environment, community relations, diversity, employee relations, human rights, and client comments was examined.
According to the findings, firms utilizing social media for CSR communication should expect improved reputation ratings. All top 20 A & D companies publish at least four CSR indicators on social media platforms. The conclusion reached is that while CSR content via social media can lead to higher reputation ratings, companies need to strategically choose the ideal number of CSR indicators, to position themselves in the global marketplace.
Categories: Faculty-Staff Graduate
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Seaplane design analysis: Focus on structure factor optimization
PI Alberto Mello
CO-I Soham Bahulekar
CO-I Sergio Butkewitshch
CO-I Wesley Queiroz
In this work, a design optimization is being investigated considering possible hydrodynamic and structural advantages aiming to reduce the structure weight factor, with a trade-off between fluid dynamics and structural aspects.
Seaplanes are known to have mandatory design characteristics that lead to disadvantages in comparison to landplanes what limit their use as regular passenger commuters. The main design points to consider are that seaplanes have higher structure weight factor due to hull with its specific shape that creates higher drag than the fuselage of a landplane. They also have higher trim drag because of the need of placing the propellers far from the water surface. All these drawbacks reduce payload capability of seaplanes. In this work, a design optimization will be investigated considering possible hydrodynamic and structural advantages aiming to reduce the structure weight factor, with a trade-off between fluid dynamics and structural aspects, increasing payload capability. An optimized structure may lead to a more effective use of seaplanes as cargo or passenger commuters. A SEAMAX M-22 currently being assembled in the ERAU Research Park hangar will be used for result comparisons.
Categories: Graduate
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Influence of cold expansion and aggressive environment on crack growth in aluminum alloy
PI Alberto Mello
CO-I Christopher Leirer
CO-I Ken Shishino
CO-I Open Position - New students are welcome
This research aims to establish the effect of hole cold expansion on fatigue life of pre-cracked material under aggressive environment.
This research investigates the relationship between crack propagation and secondary crack initiation in aluminum alloys with cold worked holes subjected to cyclic loads to determine the impact on fatigue life of joints in presence of aggressive environment. We work with experiments and analysis of fatigue life of bolted joints with coldworked holes in presence of galvanic corrosion. This investigation is examining the effect of local plastic deformation and localized galvanic corrosion on small cracks and fatigue life of bolted joints. The benefits of cold work are well known and its application is widely used in new and repaired structures, even in crack arrester holes. However, coldworked holes are usually fastened to dissimilar materials, what may induce localized galvanic corrosion. When applied in the field, damaged material removal in a cold work procedure may be limited to a maximum allowable diameter for reaming and finishing, what may leave micro/small cracks on the strained region. To completely understand the effect of initial cracks as a function of initial plastic deformation level in a coldworked hole it is necessary to fully evaluate strain distribution during and post cold work with microscopic detail. In a first approach, we have analyzed (FEM and classic analysis) and measured strain distribution during the process using digital image correlation (DIC). In the next step, we have tested specimens under fatigue. Pre cold work induced micro cracks was monitored in-situ via digital optical microscopy. In sequence, the coldworked holes were filled with a dissimilar material fastener in saline environment and the impact of galvanic corrosion on crack growth rate was determined for AA 2024-T3.
In a next step, we will further investigate the formation of critical secondary cracks. The probable cause could be a local corrosion around cathodic precipitates, but a detailed study is necessary to confirm this hypothesis. The tested samples must be prepared for use in scanning electron microscope (SEM) to identify the local pit formation at the plate edge, find the point of crack initiation, and determine the propagation path. Using striation counting technique, we may be able to estimate the number of cycles to failure and, consequently, the time necessary for the crack initiation under aggressive environment. Additionally, we will plan to use and analyze a special ceramic coating to mitigate galvanic corrosion effect on loaded components.
Categories: Graduate
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Damage Control Measures in Composites: Focus on Damage Tolerance of Aerospace Structures
PI Alberto Mello
CO-I Kais Jribi
CO-I Doug Neill (C.E.S. LLC)
CO-I Jon Gosse (C.E.S. LLC)
The focus of this research is to provide advanced methods and tools to address damage tolerance in composite structure
This study is in partnership with Computational Engineering Software, LLC (http://icmedesign.com).
Critical damage within metallic structure usually takes the form of cracks. The main issue is continued growth of the cracks as a function of in-service loading conditions. Often crack growth due to cyclic loading is of interest. Damage within composite structure has a higher number of factors to represent how critical the damage is. It must be considered that:
- Single cracks rarely exist in composite laminates, if they exist do it is usually as a delamination between adherents.
- Damage usually manifests itself as a network of inter-connected delaminations and transverse cracks.
- Unlike metals, Fracture mechanics is generally not applicable to laminated damage. The Mode I, Mode II and Mode III single crack failure modes require satisfaction of similitude to be realized in composite structures.
The main question to be answered is this study is when will the damage perimeters begin to grow under operational cyclic load. To do that, we expect to accomplish the following main steps:
Obtain limiting critical values for one or more material systems.
Develop a sequence of tests to simulate damage and then measure limits to catastrophic failure in compression and/or tension.
Model each of the test articles and apply the Onset approach to predict whether (for a given applied loading environment) the damage will or will not begin to propagate.
Compare prediction of the onset of propagation to measured ultimate failure. The criterion of success is that the numerical methodology can conservatively, but realistically predict a load level below which propagation does not occur.
Categories: Graduate
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Bird Strike - The Effect of the Leading Edge Radius on the Behavior of the Bird Upon Impact
PI Alberto Mello
CO-I Kiran Kumar Avula
CO-I James Pembridge
This project is in partnership with Gulfstream Aerospace Corporation under MMSE program.
Birds pose a major threat to aviation. Bird impact can lead to significant damage of the aircraft and can be sometimes catastrophic. For a damage tolerant design of an aircraft structure, the structure has to fulfill the airworthiness specifications prescribed by FAA or EASA.
According to FAR 25, Sub-part 25.571, leading-edge structures of large transport aircraft have to withstand an impact with a 4 lb (1.81 kg) bird (8 lb (3.62kg) for empennage leading edge) when the velocity of the airplane relative to the bird along the airplane's flight path is equal to its cruising speed (Vc) at sea level or 0.85 (Vc) at 8,000 feet, whichever is more critical.
When a bird impacts the structure, it either slides off of the impacted surface causing less damage or it creates a dent or hole due to penetration into the structure, causing significant damage. The behavior of the bird upon the impact depends on the geometrical characteristics of the structure and the velocity at which the bird impacts. When split upon impact, it results in low impact forces and thus less damage. The impact forces are higher when the bird doesn’t split upon the impact which causes more damage to the target structure as the impact forces are directly proportional to the mass of the bird.
Bird strike tests are very expensive and their number in the engine development programs should be minimized. Numerical simulations help reduce a significant amount of testing by providing valuable information in the design process. This thesis aims to develop a model using smooth particle hydrodynamics (SPH) method for analyzing aircraft leading edges for bird strikes that will correlate well with the test results and subsequently, apply the method to study the effect of the leading edge radius on the behavior of the bird (split/not split) upon the impact.
The objective is to generate sufficient data through numerical analysis to confirm the “one inch radius split/no split dividing line”, and to validate the empirical formulas used to calculate the impact forces. Overall, the goal is to save both time and money for the future generation aircraft by minimizing or eliminating the bird strike tests.
Categories: Graduate
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Predicting Pilot Misperception of Runway Excursion Risk Through Machine Learning Algorithms of Recorded Flight Data
PI Edwin Odisho
CO-I Dothang Truong
The research used predictive models to determine pilot misperception of runway excursion risk associated with unstable approaches. The Federal Aviation Administration defined runway excursion as a veer-off or overrun of the runway surface. The Federal Aviation Administration also defined a stable approach as an aircraft meeting the following criteria: (a) on target approach airspeed, (b) correct attitude, (c) landing configuration, (d) nominal descent angle/rate, and (e) on a straight flight path to the runway touchdown zone. Continuing an unstable approach to landing was defined as Unstable Approach Risk Misperception in this research. A review of the literature revealed that an unstable approach followed by the failure to execute a rejected landing was a common contributing factor in runway excursions.
Flight Data Recorder data were archived and made available by the National Aeronautics and Space Administration for public use. These data were collected over a four-year period from the flight data recorders of a fleet of 35 regional jets operating in the National Airspace System. The archived data were processed and explored for evidence of unstable approaches and to determine whether or not a rejected landing was executed. Once identified, those data revealing evidence of unstable approaches were processed for the purposes of building predictive models.
SAS™ Enterprise MinerR was used to explore the data, as well as to build and assess predictive models. The advanced machine learning algorithms utilized included: (a) support vector machine, (b) random forest, (c) gradient boosting, (d) decision tree, (e) logistic regression, and (f) neural network. The models were evaluated and compared to determine the best prediction model. Based on the model comparison, the decision tree model was determined to have the highest predictive value.
The Flight Data Recorder data were then analyzed to determine predictive accuracy of the target variable and to determine important predictors of the target variable, Unstable Approach Risk Misperception. Results of the study indicated that the predictive accuracy of the best performing model, decision tree, was 99%. Findings indicated that six variables stood out in the prediction of Unstable Approach Risk Misperception: (1) glideslope deviation, (2) selected approach speed deviation (3) localizer deviation, (4) flaps not extended, (5) drift angle, and (6) approach speed deviation. These variables were listed in order of importance based on results of the decision tree predictive model analysis.
The results of the study are of interest to aviation researchers as well as airline pilot training managers. It is suggested that the ability to predict the probability of pilot misperception of runway excursion risk could influence the development of new pilot simulator training scenarios and strategies. The research aids avionics providers in the development of predictive runway excursion alerting display technologies.
Categories: Graduate
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Investigation of Bio-Inspired Cylinders for Enhanced Heat Transfer
PI Anish Prasad
CO-I Yogesh Pai
CO-I Royce Fernandes
CO-I Mark Ricklick
This project investigates a novel cylinder design inspired from the Harbor Seal whisker, with the goal of reducing coolant pumping power requirements while maintaining heat transfer rates in pin-fin arrays.
Arrays of constant cross-section cylinders have been employed in many heat exchange applications. Increases in heat transfer rates characteristically result in an increase in the coolant pumping power requirements, which can be quite high for a circular cylinder array. Pin fin channels are often used at the trailing edge of the blades where they also serve an additional purpose of providing structural support. It has been found that the behavior of the flow around a wall-mounted cylinder significantly impacts the heat transfer. The boundary layer becomes broken up by the presence of the pin, creating a horseshoe vortex. This horseshoe vortex produces high wall shear stress beneath it, resulting in high heat transfer from the wall in this region. The resulting flow separation around the pin, however, results in large pressure losses. The pin fin channel has been heavily studied in the literature, in an effort to describe the heat transfer and flow behavior and improve prediction abilities. The circular cylindrical pins are relatively easy to manufacture and hence, this configuration is often found in commercial applications. However, the need to reduce pressure drop and maintain the heat transfer rates are a much needed requirement for a variety of industries to improve the cooling efficiency.
One such prominent line of research is conducted on optimizing the design of the circular cylindrical pins to increase their cooling performance. In this line of research, it was found that bio-mimicked harbor seal whisker geometry leads to the reduction in the cooling system pumping power requirements, while maintaining or improving heat transfer rates. The seal whisker geometry consists of stream-wise and span-wise undulations which reduce the size of the wake and coherent structures shed from the body as a result of an added component of stream-wise vorticity along the pin surface. Also, the vortex shedding frequency becomes less pronounced, leading to significantly reduced lateral loading on the modified cylinder. Preliminary computational studies have shown that the modified wake and vortex shedding structures resulting from the geometry tend to reduce the total pressure loss throughout the system without degrading the cooling levels.
Seal whisker and proposed bio-inspired cylinder:
Three different cross-section types, one elliptical, one of circular cross section and a 0.25X axially scaled type of the bio inspired pin were created for further investigation along with two baseline circular cylindrical and elliptical pins. Computational analysis for an array of the above three shapes and a standard elliptical cross-section pin array was undertaken. The results obtained were compared with the baseline circular cylindrical pin array. The main purpose of this research is to describe the heat transfer and flow characteristics of 3 novel bio inspired pin designs using steady and unsteady Reynolds-Averaged-Navier-Stokes (RANS) based simulations, in an effort to better understand their performance. These findings are important to the gas turbine community as reduced penalties associated with cooling flows directly translate to improved thermodynamic and propulsive efficiencies.
Pin-fin geometries analyzed:
Further computational research is being conducted in these geometries, and later will be compared with the experimental results, which will be carried out in Embry-Riddle's Gas Turbine Laboratory.
Categories: Graduate
11-20 of 30 results