Conceptual behavior in pigeons: Categories, subcategories, and pseudocategories.

In 3 experiments with a total of 16 Ss, we explored how pigeons learn to classify diverse pictures of cats, flowers, cars, and chairs and later how they accurately categorize brand-new pictures from these classes. Using a 4-key forced-choice procedure, Ss in Exp 1 discriminated individual examples within each of the categories from one another (subcategory training); nevertheless, errors were disproportionately conceptual in nature, with Ss more likely to confuse examples within a given category than between different categories. Ss in Exp 2 trained to classify pictures into human language categories (category training) learned far faster and more completely than Ss trained to sort the same pictures into totally arbitrary groupings (pseudocategory training). Finally, in Exp 3, category-trained and subcategory-trained Ss were tested on normally oriented pictures, on left–right reversals, and on top–bottom reversals. Subcategory-trained Ss responded less accurately on both kinds of reversed pictures and less accurately on top–bottom than on left–right reversals; category-trained Ss were less affected by both types of picture reversals, only top–bottom reversals decrementing their performance. Results suggest that many words in our language denote clusters of related visual stimuli, which pigeons also see as highly similar. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The ontogeny of long-term memory over the first year-and-a-half of life

This research documents the development of long-term memory in human infants from 2 months through the end of the first year-and-a-half of life. In the initial study phase, we trained 6- to 18-month-old human infants in an operant task and tested them after increasing delays until they exhibited no retention for 2 successive weeks. In the second phase, their data were combined with data previously obtained from 2- to 6-month-olds in an equivalent task. The resulting function revealed that the duration of retention increases monotonically between 2 and 18 months of age. This increase was not due to age differences in original learning. This is the first systematic analysis of the course of long-term memory across an extended period of infant development that is based on standardized parameters of training and testing. It provides a reference function against which measures of retention from infants of different ages that are obtained in different memory tasks with different parameters can be meaningfully compared.     

Using wavelet transforms for ECG characterization. An on-linedigital signal processing system

The rapid and objective measurement of timing intervals of the electrocardiogram (ECG) by automated systems is superior to the subjective assessment of ECG morphology. The timing interval measurements are usually made from the onset to the termination of any component of the EGG, after accurate detection of the QRS complex. This article describes a real-time system that uses wavelet transforms to overcome the limitations of other methods of detecting QRS and the onsets and offsets of P- and T-waves. Wavelet transformation is briefly discussed, and detection methods and hardware and software aspects of the system are presented, as well as experimental results     

Routing multiple paths in hypercubes

We present new techniques for mapping computations onto hypercubes. Our methods speed up classical implementations of grid and tree communications by a factor of (n), wheren is the number of hypercube dimensions. The speedups are asymptotically the best possible.We obtain these speedups by mapping each edge of the guest graph onto short, edge-disjoint paths in the hypercube such that the maximum congestion on any hypercube edge isO(1). These multiple-path embeddings can be used to reduce communication time for large grid-based scientific computations, to increase tolerance to link faults, and for fast routing of large messages.We also develop a general technique for deriving multiple-path embeddings from multiple-copy embeddings. Multiple-copy embeddings are one-to-one maps of independent copies of the guest graph within the hypercube. We present an efficient multiple-copy embedding of the cube-connected-cycles network within the hypercube. This embedding is used to derive efficient multiple-path embeddings of trees and butterfly networks in hypercubes.This research was supported by NSF/DARRA Grant CCR-8908285, NSF Grant CCR-8807426, and AFOSR Grant 89-0382.     

Investigations on N-halogen cyclic ureide based magnesium primary cell system at various temperatures

This paper reports the results of experimental studies on a magnesium/magnesium perchlorate/N,N-dichlorodimethylhydantoin cell system at various temperatures ranging from 70 to –20° C. A constant current discharge method was employed to evaluate the battery parameters such as discharge capacity, energy density, coulombic efficiency and internal resistance. Cyclic voltammetric (CV) investigations of the N,N-dichlorodimethylhydantoin (DDH) were carried out in 0.1 M magnesium perchlorate medium in order to supplement the results. Scanning electron microscopy (SEM) was performed on post-polarized magnesium samples to follow the morphological changes in the anodic material with respect to temperatures. These investigations broadly reveal that the cell system can give rise to the open-circuit/closed-circuit voltage of 2.0 V and it is possible to obtain current densities of 20 mA cm^–2 during discharge.     

Experimental investigation of top burr formation in high-speed micro-end milling of titanium alloy

ABSTRACT

Superalloys with burr-free parts are most preferably used in biomedical, aerospace, marine and automotive applications. In order to reduce the global pollution content, industries strive to execute stringent green manufacturing technologies. There is a need to investigate the different available tools in high-speed micro-milling process to achieve desired burr free with good surface finish on super alloys without using traditional coolants. In machining of titanium and its alloys, because of low thermal conductivity and reactivity with tool materials instigate the burr formation on work material and lowers the tool performance. The main objective of this article is to investigate the top burr formation in high-speed micro-end milling of alpha + beta-titanium alloy-grade 23 ELI (Ti-6Al-4V) under dry cutting conditions using Uncoated and physical vapor deposition coated AlTiN, TiAlN tungsten carbide end mills. Machining performance of the three cutting tools was compared. From the comparison of cutting tools for machining titanium alloy-grade 23, it is found that coated TiAlN tools produce less burr formation than coated AlTiN and uncoated tungsten carbide tools.     

Generalized Reynolds equation for porous boundaries

A generalized form of Reynolds equation has been obtained which permits the variation of relevant quantities across as well as along the lubricant film with porous boundaries. The equation has been derived with a minimum of restrictive assumptions and in particular cases it reduces to the various forms which other workers have developed. It is suggested that the equation derived is applicable to the various models for synovial joints and porous bearings.