A Comparison of AVIRIS and Landsat for Land Use Classification at the Urban Fringe

In this study we tested whether AVIRIS data allowed for improved land use classification over synthetic Landsat ETM+ data for a location on the urban-rural fringe of Colorado. After processing the AVIRIS image and creating a synthetic Landsat image, we used standard classification and post-classification procedures to compare the data sources for land use mapping. We found that, for this location, AVIRIS holds modest, but real, advantages over Landsat for the classification of heterogeneous and vegetated land uses. Furthermore, this advantage comes almost entirely from the large number of sensor spectral bands rather than the high Signal-to-Noise Ratio (SNR)

Mineralogical Mapping in the Cuprite Mining District, Nevada

The airborne imaging spectrometer (AIS) has provided for the first time, the possibility to map mineralogical constituents in the Earth's surface and thus has enormously increased the value of remote-sensing data as a tool in the solution of geologic problems. The question addressed with AIS at Cuprite was how well could the mineral components at the surface of a hydrothermal alteration zone be detected, identified and mapped? The question was answered positively and is discussed. A relatively rare mineral, buddingtonie, that could not have been detected by conventional means, was discovered and mapped by the use of AIS

Some effects of tip fins on wing flutter characteristics

A wind tunnel investigation has been conducted over the Mach number range from about 0.6 to 1.2 to determine the effects of large tip fins on the flutter characteristics of a swept wing. The basic wing configuration had an aspect ratio of 0.95, leading-edge sweep of 40 deg 0, and trailing-edge sweep of 21 deg. Two of these configurations were modified with tip fins of 60 deg dihedral and had effective aspect ratios of 1.5 and 2.2. In general, the results indicate that the addition of tip fins reduces the flutter speed, with the larger fin having the greater effect. Comparison of the experimental flutter speeds at Mach numbers between 0.60 and 0.90 with calculated values obtained by using doublet-lattice unsteady aerodynamic theory was good. Analytical results where structural and aerodynamic effects of the tip fins were isolated indicated that the reduction in flutter speed produced by the addition of the fins was caused by both effects, with the structural effect being the more pronounced

Double-containment coil with enhanced winding mounting for transcranial magnetic stimulation with reduced acoustic noise

Objective: This work aims to reduce the acoustic noise level of transcranial magnetic stimulation (TMS) coils. TMS requires high currents (several thousand amperes) to be pulsed through the coil, which generates a loud acoustic impulse whose peak sound pressure level (SPL) can exceed 130 dB(Z). This sound poses a risk to hearing and elicits unwanted neural activation of auditory brain circuits. Methods: We propose a new double-containment coil with enhanced winding mounting (DCC), which utilizes acoustic impedance mismatch to contain and dissipate the impulsive sound within an air-tight outer casing. The coil winding is potted in a rigid block, which is mounted to the outer casing by its acoustic nodes that are subject to minimum vibration during the pulse. The rest of the winding block is isolated from the casing by an air gap, and sound is absorbed by foam within the casing. The casing thickness under the winding center is minimized to maximize the coil electric field output. Results: Compared to commercial figure-of-eight TMS coils, the DCC prototype has 10-33 dB(Z) lower SPL at matched stimulation strength, whilst providing 22% higher maximum stimulation strength than equally focal commercial coils. Conclusion: The DCC design greatly reduces the acoustic noise of TMS while increasing the achievable stimulation strength. Significance: The acoustic noise reduction from our coil design is comparable to that provided by typical hearing protection devices. This coil design approach can enhance hearing safety and reduce auditory co-activations in the brain and other detrimental effects of TMS sound.Comment: 8 pages, 5 figure

Discretized rotation has infinitely many periodic orbits

For a fixed k in (-2,2), the discretized rotation on Z^2 is defined by (x,y)->(y,-[x+ky]). We prove that this dynamics has infinitely many periodic orbits.Comment: Revised after referee reports, and added a quantitative statemen

Invariant sets for discontinuous parabolic area-preserving torus maps

We analyze a class of piecewise linear parabolic maps on the torus, namely those obtained by considering a linear map with double eigenvalue one and taking modulo one in each component. We show that within this two parameter family of maps, the set of noninvertible maps is open and dense. For cases where the entries in the matrix are rational we show that the maximal invariant set has positive Lebesgue measure and we give bounds on the measure. For several examples we find expressions for the measure of the invariant set but we leave open the question as to whether there are parameters for which this measure is zero.Comment: 19 pages in Latex (with epsfig,amssymb,graphics) with 5 figures in eps; revised version: section 2 rewritten, new example and picture adde