Multi-colored layers for visualizing aerodynamic flow effects

A method is provided for visualizing aerodynamic flow effects on a test surface. First, discrete quantities of a sublimating chemical such as naphthalene are distinctively colored via appropriate dyes or paints. Next, a uniform layer of the sublimating chemical having a particular color is applied to the test surface. This layer is covered with a second uniform layer of a different colored sublimating chemical, and so on until a composite of multi-colored layers is formed having a discrete thickness. Friction caused by an airflow results in the distinctly colored layers being removed in proportion to such aerodynamic flow characteristics as velocity and temperature, resulting in a multi-colored portrait which approximates the air flow on the underlying test surface

IMPLICATIONS OF TAXING QUOTA VALUE IN AN INDIVIDUAL TRANSFERABLE QUOTA FISHERY: REPLY

Resource /Energy Economics and Policy,

IMPLICATIONS OF TAXING QUOTA VALUE IN AN INDIVIDUAL TRANSFERABLE QUOTA FISHERY

Taxing pure rents is usually considered the least distortionary method for raising revenues. In the literature on fishery economics, the term "rent" is regularly employed, suggesting that pure rents exist in that sector. Indeed, with the recent development of individual transferable quotas, the resulting market value of quota has been treated as reflecting pure resource rents. In this paper, the view that the market value of quota represents a pure rent that can be readily extracted in a nondistortionary manner by the taxing authority is challenged because that argument ignores both economic incentives and political realities.Resource /Energy Economics and Policy,

A relative-intensity two-color phosphor thermography system

The NASA LaRC has developed a relative-intensity two-color phosphor thermography system. This system has become a standard technique for acquiring aerothermodynamic data in LaRC Hypersonic Facilities Complex (HFC). The relative intensity theory and its application to the LaRC phosphor thermography system is discussed along with the investment casting technique which is critical to the utilization of the phosphor method for aerothermodynamic studies. Various approaches to obtaining quantitative heat transfer data using thermographic phosphors are addressed and comparisons between thin-film data and thermographic phosphor data on an orbiter-like configuration are presented. In general, data from these two techniques are in good agreement. A discussion is given on the application of phosphors to integration heat transfer data reduction techniques (the thin film method) and preliminary heat transfer data obtained on a calibration sphere using thin-film equations are presented. Finally, plans for a new phosphor system which uses target recognition software are discussed

Surface effects on hydrogen permeation through Ti-14Al-21Nb alloy

Hydrogen transport through Ti-14Al-21Nb (wt percent) alloy is measured using ultrahigh vacuum permeation techniques over the temperature range of 500 to 900 C and hydrogen pressure range of 0.25 to 10 torr. Hydrogen permeability through the alloy can be described through two different mechanisms depending on th temperature of exposure. In the 675 to 900 C range, the process is diffusion-limited: the permeability has a weak temperature dependence, but the diffusivity has a strong temperature dependence. Below 675 C, the permeation rate of hydrogen is very sensitive to surface controlled processes such as the formation of a barrier layer from contaminants. A physical model explaining the role of surface films on the transport of hydrogen through Ti-14Al-21Nb alloy was described

Saltation threshold reduction due to the electrostatic agglomeration of fine particles

Particles between 80 and 110 microns in diameter are the most easily moved by the wind. As the particle size decreases below 60 microns, they are increasingly more difficult to move by surface winds, and a number of experiments were performed in an attempt to reduce the required wind velocity. These include: (1) the bombardment of a bed of fine particles by particles near the optimum size, the larger particles kicking the fine particles into the windstream where they are entrained; and (2) the electrostatic agglomeration of fine particles into sizes more easily saltated. The results of these experiments are discussed

Recoiling DNA Molecule: Simulation & Experiment

Single molecule DNA experiments often generate data from force versus extension measurements involving the tethering of a microsphere to one end of a single DNA molecule while the other is attached to a substrate. We show that the persistence length of single DNA molecules can also be measured based on the recoil dynamics of these DNA-microsphere complexes if appropriate corrections are made to the friction coefficient of the microsphere in the vicinity of the substrate. Comparison between computer simulated recoil curves, generated from the corresponding Langevin equation, and experimental recoils is used to assure the validity of data analysis.Comment: 14 pages (single column preprint), 7 figures. Major changes: data analysis method improved; dna-ethidium bromide results removed (dna-ethidium bromide protocol affected microspheres and coverglass behavior

Uphill migration in coupled driven particle systems

In particle systems subject to a nonuniform drive, particle migration is observed from the driven to the non--driven region and vice--versa, depending on details of the hopping dynamics, leading to apparent violations of Fick's law and of steady--state thermodynamics. We propose and discuss a very basic model in the framework of independent random walkers on a pair of rings, one of which features biased hopping rates, in which this phenomenon is observed and fully explained.Comment: 8 pages, 10 figure