Effect Of The Thickness Of Undoped Gan Interlayers Between Multiple Quantum Wells And The P-Doped Layer On The Performance Of Gan Light-Emitting Diodes,
2011
Missouri University of Science and Technology
Effect Of The Thickness Of Undoped Gan Interlayers Between Multiple Quantum Wells And The P-Doped Layer On The Performance Of Gan Light-Emitting Diodes, T. Lu, S. Li, K. Zhang, C. Liu, Y. Yin, L. Wu, H. Wang, Xiaodong Yang, G. Xiao, Y. Zhou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
InGaN based light-emitting diodes (LEDs) with undoped GaN interlayer of variant thicknesses grown by metal-organic chemical vapor deposition technique have been investigated. It was found that the thickness of undoped GaN interlayers affected LEDs' performance greatly. The LED with 50 nm undoped GaN interlayer showed higher light output power and lower reverse-leakage current compared with the others at 20 mA. Based on electrical and optical characteristics analysis and numerical simulation, these improvements are mainly attributed to the improvement of the quality of depletion region by inserting an undoped GaN layer, as well as reduction of the Shockley-Read-Hall recombination in InGaN/GaN …
Space Environment-Iii Lecture - Powerpoint Presentation,
2011
Morehead State University
Space Environment-Iii Lecture - Powerpoint Presentation, Robert J. Twiggs
Robert "Bob" Twiggs STEM Education Collection
Professor Bob Twiggs' lecture on Space Environment-III PowerPoint presentation delivered on September 2, 2011.
Space Environment - A Review,
2011
Morehead State University
Space Environment - A Review, Robert J. Twiggs
Robert "Bob" Twiggs STEM Education Collection
A PowerPoint presentation created by Professor Bob Twiggs on "Space Environment" on September 2, 2011.
Mission Performance Considered As Point Performance In Aircraft Design,
2011
California Polytechnic State University, San Luis Obispo
Mission Performance Considered As Point Performance In Aircraft Design, Robert A. Mcdonald
Aerospace Engineering
The cruise or loiter performance of an aircraft is intimately tied to its wing loading and its thrust-to-weight ratio. Paradoxically, mission performance is often not considered when these fundamental aircraft parameters are determined in conceptual design. In this paper, the traditional constraint diagram is extended to include contours of range or endurance parameter. These performance metrics represent the mission-performance capability of the aircraft without sizing the aircraft to a particular mission. This gives the designer an immediate and intuitive understanding of the tradeoff between the point and mission performance of the aircraft. The potential freedom for the designer to choose …
Designing Propulsion Systems For Future Aerospace Applications,
2011
Minnesota State University - Mankato
Designing Propulsion Systems For Future Aerospace Applications, Nihad E. Daidzic
Aviation Department Publications
No abstract provided.
Advances In Hydrogen Compression Ignition Internal Combustion Engines,
2011
Missouri University of Science and Technology
Advances In Hydrogen Compression Ignition Internal Combustion Engines, Alberto Boretti
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The turbocharged direct injection lean burn Diesel engine is the most efficient engine now in production for transport applications within heavy duty trucks applications full load brake engine thermal efficiencies up to 45% and reduced penalties in brake engine thermal efficiencies reducing the load by the quantity of fuel injected. the secrets of this engine's performances are the high compression ratio and the lean bulk combustion mostly diffusion controlled in addition to the partial recovery of the exhaust energy to boost the charging efficiency. the major downfalls of this engine are the carbon dioxide emissions and the depletion of natural …
Flow Characteristics Of The Renovated Cal Poly 3 X 4 Ft Subsonic Wind Tunnel,
2011
California Polytechnic State University, San Luis Obispo
Flow Characteristics Of The Renovated Cal Poly 3 X 4 Ft Subsonic Wind Tunnel, Mathew L. Thomas, Dorian V. Pandey, Jason N. Nguyen
Aerospace Engineering
This paper investigates the flow characteristics of the renovated Cal Poly 3 x 4 ft subsonic wind tunnel. The IFA 300 constant-temperature anemometer along with a cross-plane X-wire dual-sensor probe was used to measure the mean velocity and turbulence intensity of the tunnel flow and part of the turbulent boundary layer at one section of the tunnel. Because of the malfunction of one channel of the IFA 300, only one wire of the dual sensor probe was calibrated for the measurements. The probe was then placed in a streamlined probe holder mounting on the traverse inside the wind tunnel. The …
Vibration-Based Health Monitoring Of Multiple-Stage Gear Train And Differential Planetary Transmission Involving Teeth Damage And Backlash Nonlinearity,
2011
California Polytechnic State University, San Luis Obispo
Vibration-Based Health Monitoring Of Multiple-Stage Gear Train And Differential Planetary Transmission Involving Teeth Damage And Backlash Nonlinearity, Andrew Patrick Sommer
Master's Theses
The objective of this thesis is to develop vibration-based fault detection strategies for on-line condition monitoring of gear transmission systems. The study divides the thesis into three sections. First of all, the local stresses created by a root fatigue crack on a pinion spur gear are analyzed using a quasi-static finite element model and non-linear contact mechanics simulation. Backlash between gear teeth which is essential to provide better lubrication on tooth surfaces and to eliminate interference is included as a defect and a necessary part of transmission design. The second section is dedicated to fixed axis power trains. Torsional vibration …
Stoichiometric H2ice With Water Injection And Exhaust And Coolant Heat Recovery Through Organic Rankine Cycles,
2011
Missouri University of Science and Technology
Stoichiometric H2ice With Water Injection And Exhaust And Coolant Heat Recovery Through Organic Rankine Cycles, Alberto Boretti
Mechanical and Aerospace Engineering Faculty Research & Creative Works
High power density, stoichiometric, turbocharged, directly injected engines with water injection and a three-way catalytic converter after treatment have been proposed as one of the most promising H2ICE [1]. These throttle-controlled engines have top brake efficiencies exceeding 40%, but large penalties in efficiency reducing the load with 1 bar BMEP values approaching 10%. Recovery of the large amount of fuel energy lost in the coolant especially at low loads as well as the fuel energy lost in the exhaust that is significant at high loads and speeds may push not only the top brake efficiencies to exceed the 45% mark, …
Femtosecond Laser Fabricated All-Optical Fiber Sensors With Ultrahigh Refractive Index Sensitivity: Modeling And Experiment,
2011
Missouri University of Science and Technology
Femtosecond Laser Fabricated All-Optical Fiber Sensors With Ultrahigh Refractive Index Sensitivity: Modeling And Experiment, Lan Jiang, Longjiang Zhao, Sumei Wang, Jinpeng Yang, Hai Xiao
Mechanical and Aerospace Engineering Faculty Research & Creative Works
All-optical fiber sensors based on ultracompact fiber inline Mach-Zehnder interferometer (MZI) are fabricated by side-ablating a Ushape microcavity in a single-mode optical fiber with the fiber core partially removed using femtosecond (fs) laser pulses, in which the two light paths are accordingly formed in the remaining D-type fiber core and the U-shape microcavity. Beam propagation method (BPM) analysis is utilized to illustrate the dependences of good transmission spectra on parameters including the ablation depth, ablation length and the refractive index of Ushape microcavity, which gives some guidelines to optimize parameters for fs laser micromachining and predicts RI (refractive index) sensitivities …
Sitting In The Pilot's Seat: Optimizing Human-Systems Interfaces For Unmanned Aerial Vehicles,
2011
California State University - Long Beach
Sitting In The Pilot's Seat: Optimizing Human-Systems Interfaces For Unmanned Aerial Vehicles, Steven Michael Queen, Kurt Sanner
STAR Program Research Presentations
One of the pilot-machine interfaces (the forward viewing camera display) for an Unmanned Aerial Vehicle called the DROID (Dryden Remotely Operated Integrated Drone) will be analyzed for optimization. The goal is to create a visual display for the pilot that as closely resembles an out-the-window view as possible. There are currently no standard guidlines for designing pilot-machine interfaces for UAVs. Typically, UAV camera views have a narrow field, which limits the situational awareness (SA) of the pilot. Also, at this time, pilot-UAV interfaces often use displays that have a diagonal length of about 20". Using a small display may result …
Simulation Of Wing Tip Vortices,
2011
California Polytechnic State University - San Luis Obispo
Simulation Of Wing Tip Vortices, Ryan Termath, Jason Lechniak, Keerti Bhamidipati
STAR Program Research Presentations
Modeling and Simulation (M&S) computational fluid dynamics (CFD) techniques were used to better understand wing tip vortices about a wing section. The CFD results were compared to experimental wind tunnel data derived from the University of Iowa (Ref. 2). The experiment used Stereoscopic Particle Image Velocimetry (SPIV) to measure the flow field. The SPIV data from the experiment illustrates the vortex core development and behavior downstream of the trailing edge of the wing section. Three CFD simulations using various mesh sizes and time steps were completed and compared to the experimental results. Two dimensional plots of modeled local flow field …
Unsteady Total Pressure Measurement For Laminar-To-Turbulent Transition Detection,
2011
California Polytechnic State University, San Luis Obispo
Unsteady Total Pressure Measurement For Laminar-To-Turbulent Transition Detection, Akane Sharon Karasawa
Master's Theses
This thesis presents the use of an unsteady total pressure measurement to detect laminar-to-turbulent transition. A miniature dynamic pressure transducer, Kulite model XCS-062-5D, was utilized to measure the total pressure fluctuations, and was integrated with an autonomous boundary layer measurement device that can withstand flight test conditions. Various sensor-probe configurations of the Kulite pressure transducer were first examined in a wind tunnel with a 0.610 m (2.0 ft) square test section with a maximum operational velocity of 49.2 m/s (110 mph), corresponding dynamic pressure of 1.44 kPa (30 psf). The Kulite sensor was placed on an elliptical nose flat plate …
Thermal Expansions In Wurtzite Aln, Gan, And Inn: First-Principle Phonon Calculations,
2011
Missouri University of Science and Technology
Thermal Expansions In Wurtzite Aln, Gan, And Inn: First-Principle Phonon Calculations, L.-C. Xu, R.-Z. Wang, Xiaodong Yang, H. Yan
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Using the first-principle phonon calculations under the quasiharmonic approximation, thermal expansions in III-nitrides with wurtzite AlN, GaN, and InN are reported. The results showed that it is different for each thermal expansion of three III-nitrides at low temperatures, which is consistent with their Grneisen parameters as the function of temperature. Below 50 K, negative thermal expansions occur in InN, while GaN and AlN follow the rule of positive thermal expansion. To seek the origin of positivenegative thermal expansion distinction, the mode Grneisen parameters and the phonon spectra are investigated. They indicate that different low-frequency phonon vibration modes correspond to the …
The Future Of Aerospace Propulsion: Visco-Elastic Non-Newtonian Liquids,
2011
Purdue University
The Future Of Aerospace Propulsion: Visco-Elastic Non-Newtonian Liquids, Nicole Arockiam
The Journal of Purdue Undergraduate Research
Aerospace propulsion often involves the spray and combustion of liquids. When a liquid is sprayed, large drops form first, in a process known as primary atomization. Then, each drop breaks up into smaller droplets, in a process known as secondary atomization. This determines final drop sizes, which affect the liquid’s evaporation and mixing rates and ultimately influence combustor efficiency. Little has been published concerning the secondary atomization of visco-elastic non-Newtonian liquids, such as gels. These substances have special potential as aerospace propellants, because they are safer to handle than their Newtonian liquid counterparts, such as water. Additionally, they can be …
Comparison Of Best Economy And Best Power Mixture Settings In The Purdue University Training Fleet,
2011
Purdue University
Comparison Of Best Economy And Best Power Mixture Settings In The Purdue University Training Fleet, Charles G. Chrisman
Purdue Polytechnic Directed Projects
Purdue University operates a fleet of Cirrus SR20s as training aircraft. Standard operating procedures for the cruise portion of cross country training flights call for 65% power with a best power mixture, also called rich of peak, as opposed to a best economy setting, also called lean of peak. Previous work demonstrated that fuel consumption rates, cylinder head temperatures, and true airspeeds are lower when best economy is employed compared to best power for the same power output. This study confirmed that best economy is associated with a lower fuel consumption rate and lower cylinder head temperatures but was unable …
Comparison Of Turbine Engine Test Cell Airborne Nanoparticle Count Versus Ambient Background Particle Count,
2011
Purdue University
Comparison Of Turbine Engine Test Cell Airborne Nanoparticle Count Versus Ambient Background Particle Count, Ryne Larowe
Purdue Polytechnic Directed Projects
With the establishment of the National Test Facility for Aerospace Fuels and Propulsion at Purdue University in October of 2009, new equipment has been acquired to measure and classify exhaust emissions. This facility utilizes the Honeywell F109 turbofan and Pratt & Whitney PT-6 turboprop engine test cells to analyze the emissions and engine operation of new alternative aviation fuels. This observational study investigates what, if any difference there is in the amount of ambient residual Particulate Matter (PM) in the turbofan engine test cell when compared to ambient particle count associated with the Purdue University Airport (KLAF) property. The project …
Blair Balden,
2011
Western Michigan University
Blair Balden, Margaret Von Steinen
International Faculty Researchers
A visiting professorship at the University of Passau in Passau, Germany for Dr. Blair Balden, a WMU associate professor of aviation, provided an excellent opportunity to share ideas and information about teaching aviation law with professors from Germany and Austria.
Comparison Of A High Purity Germanium Gamma Ray Spectrometer And A Multidimensional Nai(T1) Scintillation Gamma Ray Spectrometer,
2011
California Polytechnic State University, San Luis Obispo
Comparison Of A High Purity Germanium Gamma Ray Spectrometer And A Multidimensional Nai(T1) Scintillation Gamma Ray Spectrometer, Greg Stratton
Aerospace Engineering
This report compares two different gamma ray spectrometers in terms of performance, operation, and apparatus and also investigates the design and integration challenges of using gamma ray spectrometers in space. The first spectrometer is a one-dimensional high purity germanium (HPGe) spectrometer and the second is a multidimensional NaI(Tl) scintillation spectrometer (MGRS). The key results show that the HPGe exhibits 15 to 27 times better energy resolution than the MGRS, but the MGRS is 52 times more sensitive and removes 177 % more of the background radiation.
3d Cfd On An Open Wheel Race Car Front Wing In Ground Effects,
2011
California Polytechnic State University, San Luis Obispo
3d Cfd On An Open Wheel Race Car Front Wing In Ground Effects, Thomas A. Price
Aerospace Engineering
The purpose of the report is to investigate the ability of the Fluent 6.3 k-ε Realizable turbulence model with standard wall functions to model the flow around the front wing of Cal Poly’s 2008 Formula SAE car. The three primary areas of interest are ground effects, the wing wheel interaction, and the wing tip vortices. Fluent was successful at modeling the increase suction from the ground effects, and the upwash due to the wing tip vortices. The results also displayed how the high pressure region in front of the tire propagates forward and interacts with the pressure distribution around the …
