A systematic spatial bias in remembering eye positions

Categorical bias in location memory in geometric spaces is well established. The present study assessed the presence of the bias in locating eyes in images of human faces. Participants were presented with digital faces and indicated the position of one of the eyes in both upright and inverted orientations. Biases resulted from participants using multiple sources of accessible information. No differences were found for upright vs. inverted face images. Overall, the data were consistent with the retrieval category adjustment model. These distortions may be considered within the forensic context, when eyewitnesses work with a sketch artist or use a computer program to generate an image of the culprit.     

Dynamic Effects of Signal Normalizing on Adaptive Algorithms

A method is shown for suppressing the adaptive switching transient that arises in complex adaptive (LMS and stochastic approximation) algorithms due to signal normalization with controlled switched gains. The method involves rescaling of the adaptive weights with the normalizing gains just prior to the first adaptation with the new gains. In addition, an effective method of rescaling the adaptive gain factor based on the maximum eigenvalues of the respective covariance matrices is shown.     

Modern microwave power sources

The primary advantages of electron tubes over solid-state devices are that they are usually more efficient and will operate at higher temperature. Therefore, they can be smaller, tighter and still dissipate the waste heat that, unavoidably, goes along with the production of high output power. It is no accident that a one-megawatt cw microwave tube (1340 horsepower) is about the same size as a 1250 horsepower internal combustion engine. An assemblage of transistors or integrated circuits would be a much larger maze of circuit boards, power busses, cables, combiners, fuses, heat sinks, and, probably, water pipes. Unlike the situation that pertains for signal and data processing in which Moore's law applies, and complexity and performance increase while size and cost decrease in secular fashion, the transmitter built one hundred years from now will be no smaller and no lighter than the one you build today, unless the active elements are more efficient or run hotter than present-day microwave tubes. At ultra-high frequencies and above, solid-state technology has little hope of providing either advantage. The laws of thermodynamics are not man-made and cannot be broken. Many signals, including both analog and digital TV, digital communications, and EW, have high ratios of peak to average power. The poor efficiency of some microwave solid-state devices in class-A or class-AB operation when compared to that of class-AB gridded electron tubes and TWTs with multistage depressed collectors has interfered with their acceptance as amplifiers of such signals in both commercial and military service at UHF and higher frequencies. In this paper, new data on the new kinds of microwave tubes will be presented with emphasis on their suitability for application in economical, high-reliability, high-performance satellites, and communications, electronic warfare, and radar systems     

Adaptive Resource Allocation in a Spatial Spectral Processor

A method for achieving an optimal allocation of fixed computational resources in a spatial/spectral filtering system is developed. Specifically, clock cycles per unit time for a given processor are to be optimally allocated. The system is a cascade of three subsystems: an adaptive beamformer, a bandpass filter, and a spectral whitener. Each subsystem has adjustable parameters which are related to required arithmetic operations. A gradient projection algorithm is used to find a best allocation according to specified criteria. Two simulation examples are presented to show how the algorithm operates and to indicate the kind of improvement that is possible in a system design.