The effects of wing-tip droop on the aerodynamic characteristics of a delta-wing aircraft at supersonic speeds
Wing-tip droop effects on performance and stability of canard delta-wing aircraft at supersonic speeds
SUPERSONIC FLIGHT↗
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Results for “TiP”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Analysis of pressure distributions for a series of tip and trailing-edge controls on a 60 deg wing at Mach numbers of 1.61 and 2.01
Supersonic pressure distributions for tip and trailing edge controls on 60 deg delta wing
TRAILING EDGE↗
Calculated blade response at high tip-speed ratios
This paper presents the initial results of a digital computer study of helicopter rotor-blade-motion stability for a broad range of forward speeds encompassing proposed conventional and compound helicopter designs. The analysis treats the general case of nonlinear, coupled flapping and lagging motions of hinged rigid blades. The results of the study to date indicate that blade-motion stability boundaries cannot be specified for a given blade design in terms of a fixed value of rotor tip-speed ratio. The stability boundaries can shift significantly within the desired operational speed range, with the stability limits depending upon the rotor loading, the magnitude of the disturbance encountered by the blade, and the blade position at the instant the external disturbance is encountered. The sample methods suggested for improving blade-motion stability include increasing the effective hinge spring restraint by incorporating pitch-flap coupling or by using hingeless or teetering rotor systems. Reducing rotor loading also has a beneficial effect on the blade-motion stability. The results indicate that methods used to deal with the blade-motion stability problem can be expected to diminish the overall vibration levels of the helicopter rotor system across the entire design speed range.
TIP SPEED↗
Investigation of aerodynamic characteristics of an airplane configuration having tail surfaces outboard of the wing tips at Mach numbers of 2.30, 2.97, and 3.51
Aerodynamic characteristics of aircraft configuration having tail surfaces outboard of wing tips at supersonic speeds - wind tunnel stability test
AERODYNAMIC CHARACTERISTICS↗
Effect of skewed wing-tip controls on a variable-sweep wing-fuselage configuration
Skewed wing tip control effects on variable sweep wing-fuselage configuration
WING TIP CONTROL↗
Free-stream interference effects on effectiveness of control jets near the wing tip of a VTOL aircraft model
Free-stream interference effects on effectiveness of control jets near wing tip of VTOL aircraft model
VTOL AIRCRAFT↗
Systems constraints imposed on spacecraft utilizing long extendable rods with attached tip masses.
Systems constraints imposed on spacecraft utilizing long flexible rods with attached tip masses, specifically deployment and retraction problems
SYSTEMS ANALYSIS↗
Visualization and Quantification of Rotor Tip Vortices in Helicopter Flows
This paper presents an automated approach for effective extraction, visualization, and quantification of vortex core radii from the Navier-Stokes simulations of a UH-60A rotor in forward flight. We adopt a scaled Q-criterion to determine vortex regions and then perform vortex core profiling in these regions to calculate vortex core radii. This method provides an efficient way of visualizing and quantifying the blade tip vortices. Moreover, the vortices radii are displayed graphically in a plane.
Quantification↗
Tests of Full-Scale Helicopter Rotors at High Advancing Tip Mach Numbers and Advance Ratios
As a continuation of the studies of reference 1, three full-scale helicopter rotors have been tested in the Ames Research Center 40- by SO-foot wind tunnel. All three of them were two-bladed, teetering rotors. One of the rotors incorporated the NACA 0012 airfoil section over the entire length of the blade. This rotor was tested at advance ratios up to 1.05. Both of the other rotors were tapered in thickness and incorporated leading-edge camber over the outer 20 percent of the blade radius. The larger of these rotors was tested at advancing tip Mach numbers up to 1.02. Data were obtained for a wide range of lift and propulsive force, and are presented without discussion.
High Advancing Tip Mach Numbers↗
Energy Saver Guide: Tips on Saving Money and Energy at Home
Follow the simple tips in the Energy Saver guide to make your home more comfortable and easier to heat and cool--while you save money. This guide shows you how easy it is to cut your energy use at home and also on the road.
Guide, Tips, Money, Home, Saver, Consumer, Energy ↗
Tip-Induced 3D Printing on the Nanoscale with Field Emission Scanning Probes
3D printing down to the nanoscale remains a significant challenge. In this paper, the study explores the use of scanning probes that emit low-energy electrons (<100 eV) coupled with the localized injection and electron-induced decomposition of precursor molecules, for the precise localized deposition of 3D nanostructures. The experiments are performed inside the chamber of a scanning electron microscope (SEM), enabling the use of the in-built gas injector system (GIS) with gaseous naphthalene precursor for carbon deposition, as well as immediate inspection of the deposits by SEM. Substrate materials are planar fused silica with thin conductive coatings and non-planar copper wedges. After investigation of the deposition process parameters, various 2D and 3D carbon deposits are grown. Vertical nanowires several microns in length with a diameter <100 nm are achieved and 3D deposits with a high degree of nanoscale branching are also obtained, presumably due to a charging effect. High aspect ratio carbon nanostructures such as those demonstrated here can be employed as miniaturized electrodes or field emitters. The tip-based approach presented thus paves the way toward 3D nanoscale printing of various materials and functional nanostructures.
3D printing↗
A Tip-based Workflow for Sensitive IMAC-based Low Nanogram Level Phosphoproteomics
Analyzing the phosphoproteome at nanoscale poses a significant challenge, mainly due to the substantial sample loss from non-specific surface adsorption during the enrichment of low stoichiometric phosphopeptides. Here, we describe a tandem tip-based phosphoproteomics sample preparation method capable of sequential sample cleanup and enrichment without the need for additional sample transfer, thereby minimizing sample loss. Integration of this method to our recently developed SOP (Surfactant-assisted One-Pot sample preparation) and iBASIL (improved Boosting to Amplify Signal with Isobaric Labeling) approaches creates a streamlined workflow, enabling sensitive, high-throughput nanoscale phosphoproteomics measurements.
Phosphoproteome, Immobilized metal ion affinity ch↗
Review and status of tool tip frequency response function prediction using receptance coupling
This paper provides a chronological review of publications that implement and advance the receptance coupling substructure analysis (RCSA) approach first applied to tool tip receptance (or frequency response function) prediction for milling applications in 2000. The review topics mimic the RCSA approach, where the tool, holder, and spindle-machine receptances are coupled analytically, and include: tool-holder receptance modeling; connection modeling; spindle-machine receptances; and applications. The review paper summarizes contributions from multiple, international authors (198 papers) to these topics. Additionally, it provides a comprehensive resource for those beginning an investigation into RCSA.
42 ENGINEERING↗
Spatially Resolved Mapping of Three-Dimensional Molecular Orientations with ~2 nm Spatial Resolution through Tip-Enhanced Raman Scattering
We record local optical field images of silver nanocubes (75 nm) using tip-enhanced Raman (TER) spectral imaging. The images that we observe are consistent with several recent reports from our group, but here, we demonstrate sub-2 nm spatial resolution in local optical field nanoimaging under ambient laboratory conditions. This is achieved by scanning the substrate (nanocube on Si) relative to a 4-thiobenzonitrile (TBN)-functionalized Ag-coated TER probe. The spatial resolution that we obtain necessitates that only a few molecules govern the recorded optical response; molecular orientation becomes an important consideration in such measurements. We model the orientation through geometry optimization of a TBN molecule chemisorbed onto an Ag79 cluster (sphere with a ~1 nm diameter). Using the computed orientation of the cluster-bound molecule, we then model the optical response using formalism that accounts for the orientation of the molecule relative to vector components of the local optical fields. We find optimal agreement between experiment and theory. In effect, this work reveals the parallels between single-molecule Raman scattering and high-spatial-resolution TER spectroscopy, even when the images themselves cannot be used to visualize a single molecule in real space.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Power-Dependent Dual Analyte Tip-Enhanced Raman Spectral Imaging
In this work, we explore the information content in tip-enhanced Raman (TER) spectral images of gold nanoplates coated with two distinct molecular reporters: 4-thiobenzonitrile (TBN) and 4-nitrothiophenol (NTP). Using our dual analyte approach, we rigorously demonstrate pixel-limited spatial resolution in Raman nano-images that are otherwise dominated by local optical fields that vary more gently in space. Reproducibility is ensured through power dependent TERS mapping. Power-dependent imaging also (i) directly illustrates that TBN is more robust than NTP at higher laser powers, and (ii) reveals an increase in population of the Stark-tuned nitrile resonances of TBN molecules with increasing incident laser power.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Tip-Enhanced Raman Nanospectroscopy of Smooth Spherical Gold Nanoparticles
We record nanoscale-resolved chemical images of thiobenzonitrile (TBN)-functionalized smooth gold nanospheres on silicon via tip-enhanced Raman (TER) nano-spectroscopy. The recorded images trace the nascence of the familiar doughnut-shaped scattering profile of nanoparticles on silicon at its origin (the particle surface), which appears as a horseshoe-shaped scattering pattern under our experimental conditions. The local optical field maps are in agreement with their simulated finite-difference time-domain analogues. Analysis of the recorded spectra with the aid of ab initio molecular dynamics-based Raman spectral simulations further suggests that optical rectification and molecular charging take place throughout the course of atomic force microscopy-based TER nanoscale chemical imaging.
Bhattarai, Ashish↗
Spatio-Spectral Characterization of Multipolar Plasmonic Modes of Au Nanorods via Tip-Enhanced Raman Scattering
Tip-enhanced Raman (TER) spectral images of 4-thiobenzonitrile-coated Au nanorods map the spatial profiles and trace the resonances of dipolar and multipolar plasmonic modes that are characteristic of the imaged particles. For any particular rod, we observe sequential transitions between high-order modes at low frequency shifts and lower-order modes at higher frequencies. We also notice that higher-order modes (up to $m$ = 4) are generally observed for long rods as compared to their shorter analogues, where longitudinal dipolar resonances ($m$ = 1) are observable. In effect, this research adds a new dimension to local optical field mapping via TERS, which we have previously explored. Not only can the magnitudes, vector components, local/nonlocal characters of local optical fields be imaged through molecular TERS, but spatially varying local optical resonances are also direct observables.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Suppressing Molecular Charging, Nanochemistry, and Optical Rectification in the Tip-Enhanced Raman Geometry
Classical vs quantum plasmons are operative in tapping vs contact mode tip-enhanced Raman scattering (TERS) and lead to distinct observables. Under otherwise identical experimental conditions, we illustrate the concept through tapping and contact mode TERS mapping of chemically functionalized silver nanocubes. Whereas molecular charging, chemical transformations, and optical rectification are prominent observables in contact mode TERS, the same effects are suppressed using tapping mode feedback. In effect, this work demonstrates that nanoscale physical and chemical processes can be accessed/suppressed on-demand in the TERS geometry. Further, the advantages of tapping mode TERS are otherwise highlighted with the latter in mind.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗