Engineering Research & Analysis (United States)

The organocatalyst- and reagent-controlled highly selective synthesis of diversely functionalized novel 2-hydroxybenzophenone frameworks for potent UV-A/B filters is developed.

This data was collected to develop baselines for three Land Degradation Neutrality (LDN) indicators: land use and land cover change (LUC) for the period 2001-2017, soil organic carbon (SOC) stocks for 2017 and bush density for 2017 as a baseline for bush encroachment in Omusati region, Namibia.

As-manufactured rotors behave quite differently than nominal as-designed rotors due to small geometric and material property deviations in the rotor, referred to as mistuning. The mistuning of a 20 bladed, integrally bladed rotor (IBR) will be evaluated via analytical methods, benchtop testing, and using a rotating compressor research facility. Analytical methods consist of the development of an as-manufactured model based on geometry measurements from a high fidelity optical scanning system. Benchtop testing of the IBR is done using a traveling wave excitation (TWE) system that simulates engine order excitation in stationary bladed disks for the purpose of determining potentially high responding blades due to mistuning. The compressor research facility utilizes blade tip timing to measure the blade vibration of the IBR. The resonant response of the IBR at various modes and harmonic excitations is investigated. A comprehensive mistuning and force amplification comparison between the as-manufactured model, TWE, and the compressor rig is performed. Mistuning of each method is evaluated using three different methods. First, the tuned absorber factor (TAF), which is a metric to determine potential high responding blades, is determined for each system. Next, mistuning is analyzed by isolating individual blades both experimentally on the bench and analytically to determine the mistuning patterns. Lastly, the mistuning determined by each system will be evaluated using a reduced-order model, namely the fundamental mistuning model identification (FMM ID). It will be shown that TAF shows variability between each method providing indications TAF may not be the best approach of force amplification predictions. Basic mistuning agreements exist when isolating blades both experimentally and analytically exhibiting as-manufactured models are capable of representing full experiments. System ID methods provide a basic agreement between both the mistuning pattern and the mistuning amplification for all three methods analyzed. This ultimately shows the importance and the ability to use as-manufactured models to help increase detailed understanding of IBR's.

Pd(TFA)2-catalyzed cross-dehydrogenative coupling reaction for the direct C-3 arylation of quinoxalin-2-ones with arenes is described.

For the first time ever, engineers were able to observe a heatshield on the surface of another planet after a successful entry through the atmosphere. A three-week heatshield observation campaign was conducted in December 2004 after the Mars Exploration Rover Opportunity exited Endurance Crater. By utilizing the rover's scientific instruments, data was collected to make a qualitative assessment of the performance of the heatshield. This data was gathered to gain a better understanding of how the heatshield performed during entry through the Martian atmosphere. In addition, this unprecedented look at the heatshield offered engineers the opportunity to assess if any unexpected anomalies occurred. Once a survey of the heatshield debris was completed, multiple targets of interest were chosen for the collection of imaging data. This data was then used to assess the char depth of the thermal protection material, which compared well with design and post-flight computational predictions. Extensive imaging data was collected and showed the main seal in pristine conditions, and no observable indications of structure overheating. Additionally, unexpected vehicle dynamics during the atmospheric entry were explained by the observation of thermal blanket remnants attached to the heatshield.

Predicted shock-layer emission signatures during the reentry of the Japanese Hayabusa capsule are presented and compared with flight measurements conducted during an airborne observation mission in NASA's DC-8 Airborne Laboratory. For selected altitudes at 11 points along the flight trajectory of the capsule, lines of sight were extracted from flow field solutions computed using the in-house high-fidelity CFD code, DPLR. These lines of sight were used as inputs for the line-by-line radiation code NEQAIR, and emission spectra of the air plasma were computed in the wavelength range from 300 nm to 1600 nm, a range which covers all of the different experiments onboard the DC-8. In addition, the computed flow field solutions were post-processed with the material thermal response code FIAT, and the resulting surface temperatures of the heat shield were used to generate thermal emission spectra based on Planck radiation. Both spectra were summed and integrated over the flow field. The resulting emission at each trajectory point was propagated to the DC-8 position and transformed into incident irradiance to be finally compared with experimental data.

<div class="section abstract"><div class="htmlview paragraph"> Many heavy vehicles have an event data recorder (EDR) that can record pre-event and post-event information. It has been previously reported by researchers that the EDR speed is under-reported during hard braking. <span class="xref">Reust (2004)</span> and <span class="xref">Reust and Morgan (2006)</span> . Well documented tests were conducted with instrumented vehicles to measure time, speed and distance. The vehicles used for this study were equipped with engines manufactured by the Detroit Diesel Corporation. The tests also include measurement of individual wheel speeds and corresponding wheel slip. The authors offer a method to better determine true vehicle speed of a heavy vehicle with air brakes during ABS braking events by using specific speed data from the EDR. The results show that the trend of the EDR-reported speed can be used to determine a precise time of when brake initiation first began. The results of the vehicle speed and brake initiation can be used to calculate travel distance during the brake event. </div></div>