171-180 of 189 results
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ACTIVE CONTROL OF SUPERSONIC JET NOISE VIA BI-MODAL EXCITATION
Jet noise is a major problem for both military and commercial aircraft, and there is a lot of interest in ways to reduce it. In this research project sponsored by the Office of Naval Research, the objective is to implement active control in rectangular jets to reduce the noise. This is to be done by exciting the jet at a fundamental frequency as well as either a harmonic or subharmonic frequency. The amplitudes of the excitation are small, thus there should be minimal impact of excitation on aircraft performance. In doing this, we can manipulate the large-scale structures in the jet, which is the dominant noise source. The working principle here is that energy from the fundamental mode is transferred to the subharmonic or harmonic, which results in a reduction of the peak noise.
In order to compute the noise sources, High-Fidelity Large Eddy Simulations (LES) is done by modifying a code originally developed by the Air Force Research Laboratory, which uses high-order numerical schemes. However, LES is very computationally expensive and can take weeks to obtain results when running on a supercomputer. Choosing the wrong excitation parameters can result in zero noise reduction or even enhancement of the noise. To predict optimal excitation parameters, a Reduced-Order Model (ROM) has been derived to predict the propagation of noise sources in a jet. Inputs to the ROM can come from linear methods such as Linear Stability Analysis or the Linearized Euler Equations. Once the ROM is set up, a set of nonlinear differential equations can be solved numerically. By comparison, this takes only a matter of seconds and does not require the use of a supercomputing cluster. Using these results, we can observe the damping effect on the dominant noise source, and optimal excitation parameters can be chosen as inputs into LES.
Current work is focused on performing LES on a Mach 1.5 planar jet, which approximates the flow in the minor plane of a rectangular jet. This is being done to validate open-loop control using results from the ROM. Both the symmetric and asymmetric modes will be studied. Future work will involve performing LES on a Three-dimensional rectangular jet, which will be more representative of a real jet. Here, closed-loop control can also be implemented. By measuring the noise signal near the exit of the jet, parameters can be inputted to the ROM to give optimal excitation parameters thereby maximizing the noise reduction.
Categories: Faculty-Staff
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PI of the project Coalition for Undergraduate Comp, Science & Eng. Education (TUES 1244967) 2014-2016,
The project creates a cluster of collaborating institutions that combine students into common Computational Sciences and Engineering (CSE) classes and uses cyberlearning technologies to deliver instruction. Students also conduct projects that begin in a summer workshop in Embry-Riddle's Nonlinear Wave Lab and complete them at their home institution using remote lab access. Because few small colleges have the resources to provide undergraduate CSE courses, the project significantly increases student participation in computational science. The project intends to scale-up by establishing a network of clusters. The project advances the learning of CSE by using an R&D process to provide a coherent framework for designing instruction and assessing learning in which the instructional and assessment methods are aligned with a common idea: Model-based learning and reasoning. In addition, the educational infrastructure is improved by establishing a state of the art cyberlearning network that includes a virtual conferencing system; video communication between multiple endpoints such as PCs & iPads; automatic recording and archiving of sessions; and remote lab access in which all operations and measurements in the Nonlinear Wave Lab are remotely operational and streamed online.
Categories: Faculty-Staff
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NUMERICAL SIMULATIONS OF SYNTHETIC JET ACTUATOR-BASED ICE PROTECTION SYSTEMS
The project investigates numerically a novel approach to efficient icing control using an array of thermally activated synthetic jet actuators (SJAs) embedded in an aircraft surface exposed to ice accretion due to supercooled subsonic upstream flow. General aspects of the unsteady active flow control (AFC) using synthetic-jet actuation are first addressed, including integrating multiple design and analysis tools to account for various geometry and unsteady flow parameters. A numerically efficient approach is developed to allow for the natural interaction of the generated synthetic jet with the external flow without the need to model the entire actuator dynamics. The effects of SJA actuation with and without jet heating on ice accretion are next examined for a benchmark test case of the flow over a wedge. The parametric study investigates the effects of droplet distribution, SJA chamber temperature, droplet size, and freestream temperature. It is shown that the use of heated actuating SJAs may lead to complete prevention or a significant reduction in the ice accreted on the wedge surface.Categories: Faculty-Staff
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Self-sustaining Wind Energy Extraction Technique (SWEET) Using Multi-Level Control Design Methods
This international collaboration project supported by NSF-BSF grant involves ERAU Departments of Aerospace Engineering (co-PIs: Dr. Vladimir Golubev and Dr. Reda Mankbadi) and Physical Sciences (PI: Dr. William MacKunis), and Israeli Technion University (co-PI: Dr. Oksana Stalnov). The primary scientific objective of the proposed research is to investigate and experimentally validate new physics-based closed-loop active flow control methods that can be utilized to enhance the fluid kinetic energy harvesting capability of oscillating foil-based wind energy harvesting systems. Specifically, some of the challenges addressed in the conducted research stem from the conventional inability to sustain limit cycle oscillations (i.e., plunging and pitching foil displacements) and achieve continual power generation in realistic, time-varying operating conditions. The scientific objective is achieved using a ground-up multidisciplinary approach, which synergistically combines the international collaborative efforts in (1) physics-based mathematical modeling and closed-loop control design and analysis; (2) development of high-fidelity computational fluid dynamics simulations to optimize foil geometry and to test closed-loop flow control methods; and (3) experimental wind tunnel testing and validation of new closed-loop oscillating foil-based fluid kinetic energy harvesting systems under realistic conditions that foils will encounter under atmospheric boundary layer.
Categories: Faculty-Staff
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). The Engagement of Non-Traditional Students in Online Engineering Pathways.
This project aims to serve the national interest by identifying best practices for improving the persistence and advancement of adult and veteran students pursuing online engineering degrees. Through the introduction of peer leaders and synchronous recitation sessions, students will receive additional support beyond what is traditionally offered in online modalities. Moreover, peer-led team learning environments create safe havens where foundational math and engineering principles may be explored outside the instructor-student hierarchical structure. Learning from fellow students who recently completed the course can provide motivation, context, and example for undergraduate students, especially those from adult and veteran populations who may not be comfortable with online learning or perhaps have been out of the formal academic environment for some time.
The intent of the study is to inform instructional practice that other institutions can leverage to better support non-traditional students in online programs. The project will produce a peer leader training curriculum and peer-led team learning activities for introductory engineering courses including statics, aerodynamics, and digital circuits. In identifying social and academic factors under which students’ experiences in peer-led team learning produce better academic outcomes, this project hopes to advance pedagogical approaches for additional underrepresented populations and contribute to the increasing breadth of knowledge for the online education community.
Peer-led team learning has proven to be effective in face-to-face classroom settings. The scope of the current project is to implement similar structural and pedagogical practices through development of a sustainable online model that is transferable to other institutions. Goals for this project include increasing commitment to online engineering pathways, improving student persistence and advancement in online engineering programs, and identifying and mitigating cultural and structural barriers associated with non-traditional student populations. Evidence from the study will be collected from students enrolled across multiple sections of introductory engineering courses and evaluated against control sections in developing a comprehensive set of best practices. Results will advance our understanding of peer-led team learning activities’ ability to produce both statistically significant and substantially greater gains in non-traditional students’ academic performance and identity development as part of the engineering community. The EHR program supports research and development projects to improve the effectiveness of STEM education for all students. Through the Engaged Student Learning track, the program supports the creation, exploration, and implementation of promising practices and tools.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.Categories: Faculty-Staff
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OPTIMIS: Optimizing Human Performance in the Air Transportation Sector by Integrating Human Factors into Homeland Security Deterrence and Detection Procedures and Training: System Interfaces and Behavioral Screening at Security Checkpoints (Embry-Riddle Aeronautical University Undergraduate Research Collaborative Grants Program 2023)
This project addresses human performance optimization in commercial air transportation by integrating human factors principles into homeland security deterrence and detection tasks, procedures, training, and technology interfaces at airport security checkpoints.
9/11 occurred as terrorists overcame security screening procedures. Subsequently, the Transportation Security Administration (TSA) was created as a component of the U.S. Department of Homeland Security founded 20 years ago. In today’s persistent threat environment, strengthening the airport security screening checkpoint with its holistic human, social, and technological ecology in mind is an ongoing challenge. This project addresses human performance optimization in commercial air transportation by integrating human factors principles into homeland security deterrence and detection tasks, procedures, training, and technology interfaces at security checkpoints. The project takes a systemic approach in identifying behavioral risk vulnerabilities of airport security screening checkpoints associated with human error in order to: (a) close effectiveness and efficiency gaps in user interaction with systemic elements and (b) enhance human reliability as a measure to improve overall system performance and hence air transportation security. The focus is on how well system components are designed to interface with human physiological and cognitive abilities and limitations. System components include equipment and technology, tasks, environment, and organizational elements. Organizational elements include scheduling/shiftwork, training, culture, communication, procedures, etc. Expected outcomes include focused controls associated with fatigue/circadian dysrhythmia and development of training materials for improved recognition of behavioral threat risks indicators.Categories: Faculty-Staff
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Analyticity and kernel stabilization of unbounded derivations on C*-algebras
We first show that a derivation studied recently by E. Christensen has a set of analytic elements which is strong operator topology-dense in the algebra of bounded operators on a Hilbert space, which strengthens a result of Christensen. Our second main result shows that this derivation has kernel stabilization, that is, no elements have derivative eventually equal to 0 unless their first derivative is 0. As applications, we (1) show that a family of derivations on C*-algebras studied by Bratteli and Robinson has kernel stabilization, and (2) we provide sufficient conditions for when two operators which satisfy the Heisenberg Commutation Relation must both be unbounded.
Categories: Faculty-Staff
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Simulation Based Inquiry Oriented Linear Algebra
CO-I Ashish Amresh
Games that teach introductory concepts in linear algebra such as vectors, span and dependence are created to be used by instructors in an undergraduate class.
A well-established National workforce need and critical challenge is to recruit and train students in Science, Technology, Engineering and Mathematics (STEM) fields. Since mathematics is a fundamental part of all STEM disciplines, success of undergraduate students in mathematics is a crucial ingredient to address this challenge. Linear algebra is a vital transition course for students in the STEM disciplines because of its unifying power within mathematics and its applicability to areas outside of mathematics. Accordingly, effective instruction at this stage in students' development is paramount. The focus of this project will be to improve teaching, learning, and student success in linear algebra by incorporating a blending of technology and several learning theories and applications to lead to new research results and production of curriculum resources. This project will leverage the investigators' previous research and curriculum development in Inquiry-Oriented Linear Algebra (IOLA) and expertise in Technology Based Learning to explore the unification of curriculum design and technology design theories and practices.
The goals of the project are to: (1) create a digital platform that will equip students with a virtual experience of a version of the IOLA curriculum; (2) document the affordances and constraints for learning using a game platform (IOLA-G) in comparison to face-to-face instruction by experienced IOLA instructors; (3) compare different digital gaming formats to determine which are most conducive to inquiry-oriented learning; and (4) use the knowledge gained from (1), (2), and (3) to improve student learning through the developed technology, and, reflexively, to enhance the existing IOLA curriculum and teacher support resources. The project team will investigate students' mathematical activity and learning while the students are engaged with the digital platform and will use this insight to inform further refinement of design. Building on prior research efforts in the learning and teaching of linear algebra and expertise in Game Based Learning (GBL), the team will design IOLA-G to mimic the problem-centered approach of the existing IOLA curriculum and will iteratively refine this platform through teaching experiments with students throughout the project. The project also will explore the extent to which GBL can provide a dynamic approach to addressing the constraints that larger class sizes place on instructors' implementation of inquiry-oriented curricula. In addition to, and as part of the process of, creating the resource technology, the investigators will incorporate a mixed methods approach with a blending of game-based learning design, curriculum design theory, and research from inquiry-based learning to explore the following research questions: What are the mathematical practices that students engage in and the conceptual understandings students develop using IOLA-G compared to when using only the face-to-face IOLA curriculum? What are the affordances and constraints of different game environments in terms of enacting an inquiry-oriented curriculum? The impact of the project will include the positive effects on STEM discipline student learning, knowledge, abilities, and overall success, which will lead to strengthening United States workforce needs in STEM areas.Categories: Faculty-Staff
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The S-Band Array for Bistatic Electromagnetic Ranging (SABER)
CO-I Brian Butka
Faculty in the Electrical, Computer, Software, and Systems Engineering Department at Embry-Riddle are developing new radar that may alter the paradigm of locating aircraft.
Unlike standard radars that generate high-power radio pulses and listen for the return echoes indicating aircraft, the SABER system has no transmitter of its own. Instead, the researchers use weak echoes of signals from existing satellites high above the Earth to locate their quarry.Passive radars exploiting environmental signals are not uncommon and systems using television and radio stations have been known for more than a decade; however, systems using satellites are unique. Satellite signals are much weaker than ground-based signals, and are often considered too weak to be useful. The key, says Barott, is in the signal processing, which is able to identify the very weak echoes - and thus the aircraft - among the sea of radio noise and interfering signals.
Passive radars exploiting environmental signals are not uncommon and systems using television and radio stations have been known for more than a decade; however, systems using satellites are unique. Satellite signals are much weaker than ground-based signals, and are often considered too weak to be useful. The key, says Barott, is in the signal processing, which is able to identify the very weak echoes - and thus the aircraft - among the sea of radio noise and interfering signals.The researchers envision many applications for passive radars using satellite-based signals. To start with, a network of inexpensive stations could supplement existing systems for tracking low-altitude aircraft, and provide coverage in mountainous regions where little radar coverage currently exists. “It's a similar idea to why you might get satellite television,” says Barott. “Remote locations and rough terrain might block ground-based signals, but are no problem for satellites sending their signals down from orbit.” Other applications include rapid deployment radars and approach radars for remote airfields. The researchers also note potential applications utilizing the covert and stealth-detecting aspects of this type of radar
Categories: Faculty-Staff
171-180 of 189 results