Langley Research Center

About: Langley Research Center is a facility organization based out in Hampton, Virginia, United States. It is known for research contribution in the topics: Mach number & Wind tunnel. The organization has 15945 authors who have published 37602 publications receiving 821623 citations. The organization is also known as: NASA Langley & NASA Langley Research Center.

The International Reference Ionosphere 2012 – a model of international collaboration

Abstract: The International Reference Ionosphere (IRI) project was established jointly by the Committee on Space Research (COSPAR) and the International Union of Radio Science (URSI) in the late sixties with the goal to develop an international standard for the specification of plasma parameters in the Earth’s ionosphere. COSPAR needed such a specification for the evaluation of environmental effects on spacecraft and experiments in space, and URSI for radiowave propagation studies and applications. At the request of COSPAR and URSI, IRI was developed as a data-based model to avoid the uncertainty of theory-based models which are only as good as the evolving theoretical understanding. Being based on most of the available and reliable observations of the ionospheric plasma from the ground and from space, IRI describes monthly averages of electron density, electron temperature, ion temperature, ion composition, and several additional parameters in the altitude range from 60 km to 2000 km. A working group of about 50 international ionospheric experts is in charge of developing and improving the IRI model. Over time as new data became available and new modeling techniques emerged, steadily improved editions of the IRI model have been published. This paper gives a brief history of the IRI project and describes the latest version of the model, IRI-2012. It also briefly discusses efforts to develop a real-time IRI model. The IRI homepage is at http://IRImodel.org.

Electrohydrodynamic Flow Control with a Glow-Discharge Surface Plasma

Abstract: Multiplee ow diagnostics have been applied to planarpanels covered by strips of glow-discharge surface plasma in atmospheric pressure air generated by the one atmosphere uniform glow discharge plasma. Direct drag measurements, smoke wire and titanium tetrachloride e ow visualization, and boundary-layer velocity proe les were obtained. The plasma generated along streamwise-oriented, symmetric strip electrodes is shown to cause a large increase in drag, whereas the plasma along spanwise-oriented, asymmetric strip electrodes can generate a signie cant thrust. Flow visualization and mean velocity measurements show the primary cause of the phenomena to be a combination of mass transport and vortical structures induced by strong electrohydrodynamic body forces on the e ow, known as paraelectric forcing.

Low-cost piezocomposite actuator for structural control applications

Abstract: The design, manufacture, and testing of a low-cost, flexible, planar composite piezoceramic actuator device will be presented. The actuator uses interdigitated electrodes for poling and subsequent actuation of an internal layer of machined piezoceramic fibers. The fiber sheets are formed from monolithic piezoceramic wafers and conventional computer controlled wafer-dicing methods. The fabrication and use of fiber sheets allows precise handing and alignment of piezoceramic fibers during subsequent phases of actuator assembly. Test show that the actuator is capable of producing large, directional in-plane strains; on order of 2000 parts-per-million under a 4000 V peak-to-peak applied voltage cycle. Preliminary endurance testing indicates that the device is relatively durable, with no reductions in free-strain performance up to 90 million electrical cycles.

The Earth Radiation Budget Experiment (ERBE).

Abstract: The three-satellite ERBE will be flown in the mid-1980s and will provide upgraded data on changes in the input and outflow of energy which drives climatic phenomena. The spacecraft will carry radiometers, self-calibration equipment, and be programmed with inversion and averaging algorithms. Radiation will be scanned at 0.2-5 and 5-50 microns. The ACRIM detector, similar to that on the SMM spacecraft, will measure the incoming solar radiation at the 600 km sun-synchronous orbit travelled by the three ERBE spacecraft. Data transmitted to the NASA-Langley Center will be analyzed with algorithms which extract radiant flux data from the measured radiances.

Transport and Chemical Evolution over the Pacific (TRACE-P) aircraft mission: Design, execution, and first results

Abstract: The NASA Transport and Chemical Evolution over the Pacific (TRACE-P) aircraft mission was conducted in February-April 2001 over the NW Pacific (1) to characterize the Asian chemical outflow and relate it quantitatively to its sources and (2) to determine its chemical evolution. It used two aircraft, a DC-8 and a P-3B, operating out of Hong Kong and Yokota Air Force Base (near Tokyo), with secondary sites in Hawaii, Wake Island, Guam, Okinawa, and Midway. The aircraft carried instrumentation for measurements of long-lived greenhouse gases, ozone and its precursors, aerosols and their precursors, related species, and chemical tracers. Five chemical transport models (CTMs) were used for chemical forecasting. Customized bottom-up emission inventories for East Asia were generated prior to the mission to support chemical forecasting and to serve as a priori for evaluation with the aircraft data. Validation flights were conducted for the Measurements Of Pollution In The Troposphere (MOPITT) satellite instrument and revealed little bias (6 plus or minus 2%) in the MOPITT measurements of CO columns. A major event of transpacific Asian pollution was characterized through combined analysis of TRACE-P and MOPITT data. The TRACE-P observations showed that cold fronts sweeping across East Asia and the associated warm conveyor belts (WCBs) are the dominant pathway for Asian outflow to the Pacific in spring. The WCBs lift both anthropogenic and biomass burning (SE Asia) effluents to the free troposphere, resulting in complex chemical signatures. The TRACE-P data are in general consistent with a priori emission inventories, lending confidence in our ability to quantify Asian emissions from socioeconomic data and emission factors. However, the residential combustion source in rural China was found to be much larger than the a priori, and there were also unexplained chemical enhancements (HCN, CH3Cl, OCS, alkylnitrates) in Chinese urban plumes. The Asian source of CCl4 was found to be much higher than government estimates. Measurements of HCN and CH3CN indicated a dominant biomass burning source and ocean sink for both gases. Large fractions of sulfate and nitrate were found to be present in dust aerosols. Photochemical activity in the Asian outflow was strongly reduced by aerosol attenuation of UV radiation, with major implications for the concentrations of HOx, radicals. New particle formation, apparently from ternary nucleation involving NH3, was observed in Chinese urban plumes.