Experimental and theoretical aerodynamic characteristics of a high-lift semispan wing model

Experimental and theoretical aerodynamic characteristics were compared for a high-lift, semispan wing configuration that incorporated a slightly modified version of the NASA Advanced Laminar Flow Control airfoil section. The experimental investigation was conducted in the Langley 14- by 22-Foot Subsonic Tunnel at chord Reynolds numbers of 2.36 and 3.33 million. A two-dimensional airfoil code and a three-dimensional panel code were used to obtain aerodynamic predictions. Two-dimensional data were corrected for three-dimensional effects. Comparisons between predicted and measured values were made for the cruise configuration and for various high-lift configurations. Both codes predicted lift and pitching moment coefficients that agreed well with experiment for the cruise configuration. These parameters were overpredicted for all high-lift configurations. Drag coefficient was underpredicted for all cases. Corrected two-dimensional pressure distributions typically agreed well with experiment, while the panel code overpredicted the leading-edge suction peak on the wing. One important feature missing from both of these codes was a capability for separated flow analysis. The major cause of disparity between the measured data and predictions presented herein was attributed to separated flow conditions

Triplet exciton transport in isotopic mixed naphthalene crystals. I. Kinetic analysis of trapping and fusion

Time‐resolved triplet exciton transport in binary mixed crystals has been studied for C10H8 in C10D8 (20%–100%) at liquid helium temperatures. The delayed fluorescence decays are exponential and range from milliseconds to nanoseconds as Cg goes from 0.2 to 1.0. The analysis is based on the presence of a BMN supertrap in large amounts (10−3) and on the fact that supertrapping of the guest excitons dominates the kinetics while heterofusion (triplet guest‐triplet supertrap annihilation) dominates over the homofusion (guest–guest annihilation) and was used to monitor the kinetics. We also investigated in detail photodetrapping and the relative efficiencies of the various fusion channels. An analysis of the transport data is given in paper II.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70437/2/JCPSA6-81-7-3014-1.pd

Singlet exciton transport in substitutionally disordered naphthalene crystals: Percolation and generalized diffusion@fa@f)

Experimental data is presented for singlet exciton transport in a ternary naphthalene system (C10H8/C10D8/BMN). The trapping probability varies with guest concentration and with temperature. The data at 4.2 K are consistent with a generalized diffusion treatment such as that proposed by Gochanour, Andersen, and Fayer. The 1.8 K data conform to a quasistatic percolation model. The supertrap induced energy funnels which might affect this energy transport are limited to nearest neighbors. The BMN fluorescence spectra are affected by exciton–phonon interactions similar to Herzberg–Teller coupling.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70050/2/JCPSA6-78-1-373-1.pd

Speech Delay in Seven Siblings with Unusual Sound Preferences

By the age of 8 years, children who are developing normally show almost adult speech skills. Children with serious phonological disorders, however, may exhibit significant differences in development well beyond the age of 8 years with little or no improvement in speech if therapy is not provided. This is a descriptive study of seven siblings, ranging in age from 6 to 14 years of age who had never attended school or received speech therapy until these ages. All of the children exhibited moderate to severe speech disorder with no evidence of predisposing genetic factors, hearing loss, physical abuse, or prenatal drug exposure. These cases, which would obviously be impossible to duplicate in a controlled study, provide strong support for the efficacy of speech therapy. Children with serious speech delays will not improve appreciably without direct intervention

Triplet exciton transport in isotopic mixed naphthalene crystals. II. Master equation analysis

The experimental data on triplet exciton transport in isotopically mixed crystals of naphthalene/perdeuteronaphthalene (paper I) are contrasted with singlet exciton transport in the same samples (20%–100%) and analyzed in terms of incoherent hopping models. The master equation approach is emphasized and extended. We modify the conventional continuum master equations via a physically plausible cutoff of the high‐frequency transfer rates. This results in an experimentally acceptable functional form (transport linear with high power of concentration) and nearest‐neighbor transfer time (100 ps). We also developed a lattice master equation (numerically soluble), using an experimentally tested exciton superexchange formula. The somewhat surprising result is that the lattice master equations do not fit the experimental functional form. The success of the continuum models and the failure of the lattice models are attributed to the latter’s neglect of the spread in transfer rates for a given intersite distance. We claim that clusterization as well as diagonal homogeneous and/or inhomogeneous disorder cause the above spread. On the other hand, these energy mismatches are small with respect to the thermal energy, in contrast to the singlet exciton transport case, where, due to larger energy mismatches, a percolation‐like critical concentration is observed. Thus for the given concentration and temperature regimes, the triplet exciton transport is diffusive while the singlet exciton transport is percolative. Lower temperatures and/or concentrations are required for percolative triplet energy transport in these systems.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70331/2/JCPSA6-81-7-3022-1.pd

The Langley 14- by 22-Foot Subsonic Tunnel: Description, Flow Characteristics, and Guide for Users

The Langley 14- by 22-foot Subsonic Tunnel is a closed circuit, single-return atmospheric wind tunnel with a test section that can be operated in a variety of configurations (closed, slotted, partially open, and open). The closed test section configuration is 14.5 ft high by 21.75 ft wide and 50 ft long with a maximum speed of about 338 ft/sec. The open test section configuration has a maximum speed of about 270 ft/sec, and is formed by raising the ceiling and walls, to form a floor-only configuration. The tunnel may be configured with a moving-belt ground plane and a floor boundary-layer removal system at the entrance to the test section for ground effect testing. In addition, the tunnel had a two-component laser velocimeter, a frequency modulated (FM) tape system for dynamic data acquisition, flow visualization equipment, and acoustic testing capabilities. Users of the 14- by 22-foot Subsonic Tunnel are provided with information required for planning of experimental investigations including test hardware and model support systems

Evaluation and Demonstration of BMPs for Cattle on Grazing Lands for the Lone Star Healthy Streams Program

According to the 2008 Texas Water Quality Inventory and 303(d) List, recreation is impaired in 274 waterbody segments and oyster harvest is impaired in another 21 due to bacteria. One of the primary strategies for reducing bacteria in many of these waterbodies is to provide technical and financial assistance to implement best management practices (BMPs) to reduce bacteria runoff from cattle on grazing lands. In order to inspire behavior change, evaluations and demonstrations of BMP effectiveness are needed to encourage voluntary implementation of BMPs and participation in federal and state technical and financial assistance programs designed to reduce bacterial runoff ultimately improve water quality. The goal of this project was to reduce bacterial contamination caused by grazing livestock in Texas waterbodies through evaluation and demonstration of BMP effectiveness in reducing bacteria runoff from grazing lands. This BMP effectiveness data then served as the scientific-basis for the Lone Star Healthy Streams education program (grazing cattle component). Lone Star Healthy Streams programs and other outreach and technology transfer were utilized to increase voluntary implementation of BMPs and participation in federal and state technical and financial assistance programs by providing landowners with feasible options for addressing sources of bacteria through education programs based on the evaluation and demonstration of BMP effectiveness

Low-speed aerodynamic characteristics of a twin-engine general aviation configuration with aft-fuselage-mounted pusher propellers

An investigation was conducted to determine the aerodynamic characteristics of an advanced turboprop aircraft model with aft-pylon-mounted pusher propellers. Tests were conducted through an angle-of-attack range of -8 to 28 degrees, and an angle-of-sideslip range of -20 to 20 degrees at free-stream conditions corresponding to Reynolds numbers of 0.55 to 2.14 x 10 to the 6th power based on mean aerodynamic chord. Test results show that for the unpowered configurations the maximum lift coefficients for the cruise, takeoff, and landing configurations are 1.45, 1.90, and 2.10, respectively. Nacelle installation results in a drag coefficient increase of 0.01. Increasing propeller thrust results in a significant increase in lift for angles of attack above stall and improves the longitudinal stability. The cruise configuration remains longitudinally stable to an angle of attack 5 degrees beyond the stall angle, the takeoff configuration is stable 4 degrees beyond stall angle, and the landing configuration is stable 3 degrees beyond stall angle. The predominant effect of symmetric thrust on the lateral-directional aerodynamic characteristics is in the post-stall region, where additional rudder control is available with power on

Profiles of cash flow components

Includes bibliographical references (p. 20-22)