Further experiments on successiveness discrimination
Uncertainty effect on successiveness discrimination function and variation effect in standard interval on forced choice successiveness discrimination
HUMAN PERFORMANCE↗
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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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Speed tuning of motion segmentation and discrimination
Motion transparency requires that the visual system distinguish different motion vectors and selectively integrate similar motion vectors over space into the perception of multiple surfaces moving through or over each other. Using large-field (7 degrees x 7 degrees) displays containing two populations of random-dots moving in the same (horizontal) direction but at different speeds, we examined speed-based segmentation by measuring the speed difference above which observers can perceive two moving surfaces. We systematically investigated this 'speed-segmentation' threshold as a function of speed and stimulus duration, and found that it increases sharply for speeds above approximately 8 degrees/s. In addition, speed-segmentation thresholds decrease with stimulus duration out to approximately 200 ms. In contrast, under matched conditions, speed-discrimination thresholds stay low at least out to 16 degrees/s and decrease with increasing stimulus duration at a faster rate than for speed segmentation. Thus, motion segmentation and motion discrimination exhibit different speed selectivity and different temporal integration characteristics. Results are discussed in terms of the speed preferences of different neuronal populations within the primate visual cortex.
NASA Center ARC↗
Discriminative Methodology using the Unscented Transform in Special Euclidean Group SE(3) for Autonomous GN&C
Kalman filtering techniques usually compare a known dynamic model with some process noise to an updated, noisy measurement. Both sources of noise are generally assumed to be Gaussian and are filtered to obtain a more accurate estimate of the state of the system of interest. However, these methods assume that a relatively accurate dynamical model already exists. By including discriminative methodology to interpret differences in the predictive model and the measured states over time, an incorrect model can be corrected overtime, allowing a spacecraft to learn about its environment and adapt to changing conditions. In this paper, a discriminative unscented Kalman filter (DUKF) is introduced on the special Euclidean group SE(3) formulation framework. A spacecraft is initialized near a small body with no knowledge of its parameters, and using several consecutive conditional models the environment is studied and the filter is updated. The case study of a spacecraft in a slightly elliptical, inclined, relatively tight orbit around the irregular moon Phobos is simulated and discussed. The accuracy of this approach is quantifying the differences between the true state, the UKF with a poor model, and the DUKF.
GN&C↗
Digitally controlled pulse-level discriminator operates over wide voltage range
Low power drain discriminator circuit generates an output pulse when an input pulse exceeds a discrete digitally controlled threshold voltage. The discriminator operates over a wide linear or nonlinear range of threshold levels. It uses several amplifier stages ahead of a fixed-reference threshold detector.
Cancro, C. A.↗
Improved pulse shape discriminator for fast neutron-gamma ray detection system
Discriminator in nuclear particle detection system distinguishes nuclear particle type and energy among many different nuclear particles. Discriminator incorporates passive, linear circuit elements so that it will operate over a wide dynamic range.
Lockwood, J. A.↗
Average evoked potential correlates of two-flash perceptual discrimination in cats.
Average evoked potentials (AEPs) were recorded from the optic tract, lateral geniculate nucleus, and visual cortex of cats trained to discriminate between two successive flashes of light at various interflash intervals (IFI) and a single flash. The percent of correct responses to two-flash stimuli decreased sharply as IFI decreased from 100 to 20 msec. This behavioral response decrement was paralleled by a progressive overlapping of the AEPs to the two flashes and at 20 msec the AEPs resembled those to a single flash at all levels of the visual pathways. Implications for the coding of the information relevant to the discrimination of two flashes are discussed.
Peck, C. K.↗
Improved discrimination in photographic density contouring
Density discrimination can be accomplished through use of special photographic contouring material which has two sensitive layers (one negative, one positive) on single support. Process will be of interest to investigators who require finer discrimination of densities of original photograph for purposes such as identification of crops and analysis of energy levels of radiating objects.
Godding, R. A.↗
Application of frequency discrimination technique to the analysis of electroencephalographic signals
A frequency discrimination technique is realized by an inexpensive frequency discriminator for direct on-line measurement of the entrainment phenomenon in EEG as entrained by the frequency of a sensory stimulus. The use of this device for detecting the presence or absence of the stimulus effect and the measurement of the time delays in the entrainment is demonstrated. The EEG signal is first filtered by a narrow-band filter with center frequency about the alpha-rhythm of the individual. It is then reasonable to consider the alpha signal as narrow-band random process with the alpha frequency f sub alpha as the mean frequency of the spectral band.
Lai, D. C.↗
Characteristics of cesium iodide for use as a particle discriminator for high energy cosmic rays
The possible use of CsI to discriminate between high energy cosmic ray electrons and interacting protons has been investigated. The pulse-shape properties as a function of ionization density, temperature, and spectral response are presented for thallium-activated CsI and as a function of ionization density for sodium-activated CsI. The results are based on previously published data and on corroborative measurements from the present work. Experimental results on the response of CsI to electron-induced electromagnetic cascades and to interacting hadrons are described. Bibliographies of publications dealing with the properties of CsI and with pulse-shape discrimination techniques are presented.
Crannell, C. J.↗
A slope reversal video processor having amplitude and pulse width discrimination.
A timing discriminator whose output is relatively insensitive to input pulse width and amplitude is described. The video-handling technique is known as slope reversal processing and is based on tapped delay line estimation methods. The concept, design, breadboard construction, and preliminary laboratory test results are reviewed. The processor system features (1) a peak input voltage dynamic range of 80x starting at 100 microvolts; (2) a four stage preamplifier/line-driver having a voltage gain of 2400x; (3) a tapped delay-line estimator implemented for slope reversal triggering by differential comparison; (4) a nominal plus or minus 2.5 nsec shift of the output trigger leading edge over the entire input voltage range, (5) up to 7 dB discrimination against pulse widths less than 35 nsec; and (6) up to one order of magnitude reduction in the false alarm rate compared to a constant fraction system.
Hoge, F. E.↗
Development of a two channel linear discriminant function for detecting and identifying surface water using ERTS-1 data
A method for detecting surface water using ERTS-1 multispectral scanner digital data is described. The several computer programs for processing multispectral data are described, along with the manner in which these programs were used. The use of the LARSAA program to test and demonstrate the discriminant function is explained. The discriminant function itself was later implemented in an operational program which performs only those specific operations necessary to test each data point for an indication of surface water in the scene. Several possible sources of difficulty in the use of the function are identified, and suggestions are made for avoiding or correcting those difficulties.
Source record↗
An evaluation of multiband photography for rock discrimination
The ability of multiband photography to discriminate sedimentary rocks is investigated. Measurements showed that there is a large natural variation in the band reflectance of rock formations and that the differences in the contrast ratios for different Wratten filters is small, making it statistically impossible to select a set of best bands from in situ reflectance measurements. It is concluded that the designed multiband photography concept is not a practical method for improving sedimentary-rock discrimination capabilities.
Raines, G. L.↗
Intermodal transfer in temporal discrimination
This study determined if training for accuracy in temporal discrimination would transfer across sensory modalities. A fractionation method was used in which subjects bisected the durations of acoustic and visual signals at three standard intervals (6, 12, and 18 sec). Absolute error was the performance index. Half of the subjects were trained with acoustic stimuli and then tested in vision; the remainder were trained in vision and tested in audition. Similar negatively accelerated acquisition functions were noted for both modalities. Positive intermodal transfer, characterized by symmetry across modalities, was obtained at all standard durations. The results were considered to provide support for the notion that a common mechanism underlies temporal discriminations in different sensory systems.
Warm, J. S.↗
Optimum spectral bands for rock discrimination
Using stepwise discriminant analysis on spectral reflectance and spectral emissivity data collected by a Multispectral Scanner and Data System, mounted in an NC-130B aircraft and flown at an altitude of approximately 3 km, spectral bands were ranked as to their usefulness in separating specific rock types and rock alteration products in seven geologically diverse Utah sites. The optimum band for rock discrimination included the 1.18 to 1.30 micron interval, and the optimum combination of bands comprised the 1.18 to 1.30, 4.50 to 4.75, 0.46 to 0.50, 1.52 to 1.73, and 2.10 to 2.36 micron intervals. It is concluded that the spectral interval combination was more successful in differentiating geologic materials than either simulated Multispectral Scanner bands or simulated Thematic Mapper bands.
Siegrist, A. W.↗
Discriminator aided phase lock acquisition for suppressed carrier signals
A discriminator aided technique for acquisition of phase lock to a suppressed carrier signal utilizes a Costas loop which is initially operated open loop and control voltage for its VCXO is derived from a phase detector that compares the VCXO to a reference frequency thus establishing coarse frequency resolution with the received signal. Then the Costas loop is closed with the low-pass filter of the channel having a bandwidth much greater (by a factor of about 10) than in the I channel so that a frequency discriminator effect results to aid carrier resolution. Finally, after carrier acquisition, the Q-channel filter of the Costas loop is switched to a bandwidth substantially equal to that of the I-channel for carrier tracking.
Carson, L. M.↗
Radar image processing for rock-type discrimination
Image processing and enhancement techniques for improving the geologic utility of digital satellite radar images are reviewed. Preprocessing techniques such as mean and variance correction on a range or azimuth line by line basis to provide uniformly illuminated swaths, median value filtering for four-look imagery to eliminate speckle, and geometric rectification using a priori elevation data. Examples are presented of application of preprocessing methods to Seasat and Landsat data, and Seasat SAR imagery was coregistered with Landsat imagery to form composite scenes. A polynomial was developed to distort the radar picture to fit the Landsat image of a 90 x 90 km sq grid, using Landsat color ratios with Seasat intensities. Subsequent linear discrimination analysis was employed to discriminate rock types from known areas. Seasat additions to the Landsat data improved rock identification by 7%.
Blom, R. G.↗
Enhanced crop discrimination using the mid-IR (1.55-1.75 microns)
Improvements in crop discrimination can be realized by using mid-IR bands (1.55 -1.75 and 2.08 -2.35 microns) which are sensitive to canopy moisture content. Analyses of data from two growing seasons in Webster County, Iowa clearly indicate that corn and soybeans are highly separable in the mid-IR from early season through harvest. This contrasts sharply with visible and near-IR bands where corn and soybeans are confused throughout much of the growing season. The mid-IR temporal reflectance behavior appears to result from differences between C4 monocot and C3 dicot internal leaf structure. If this hypothesis holds, mid-IR observations should improve discrimination in other instances where similar differences in internal leaf structure are present.
Ungar, S. G.↗
Discriminator Aids Phase-Lock Acquisition
Voltage-controlled oscillator in suppressed-carrier detector acquire carrier frequency and phase quickly with help of frequency-discriminator arrangement. To obtain discriminator function, filter bandwidth in quadrature (Q) leg of detector is widened with respect to bandwidth of filter in inphase (l) leg.
Carson, L. M.↗