Deduction as verbal reasoning.

Most theories of deduction have assumed that linguistic processes transduce from language into an internal representation and back again, and that non-linguistic processes are central to deduction itself. In this article it is proposed that for deduction tasks for which the necessary information is provided verbally, the heart of deduction for untrained participants involves repeatedly reencoding the problem, a type of behavior referred to here as verbal reasoning. It is shown that model theory accounts of behavior on most deduction tasks are consistent with verbal reasoning and that verbal reasoning can account for detailed behavior in a single task; a computational model of syllogistic reasoning—VR—based on linguistic mechanisms is presented. VR models all of the standard phenomena, makes a number of accurate novel predictions, and fits the behavior of individual participants with an accuracy that rivals their own test–retest reliability. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The perceptive workbench: Computer-vision-based gesture tracking,object tracking,and 3D reconstruction for augmented desks

Abstract. The Perceptive Workbench endeavors to create a spontaneous and unimpeded interface between the physical and virtual worlds. Its vision-based methods for interaction constitute an alternative to wired input devices and tethered tracking. Objects are recognized and tracked when placed on the display surface. By using multiple infrared light sources, the object's 3-D shape can be captured and inserted into the virtual interface. This ability permits spontaneity, since either preloaded objects or those objects selected at run-time by the user can become physical icons. Integrated into the same vision-based interface is the ability to identify 3-D hand position, pointing direction, and sweeping arm gestures. Such gestures can enhance selection, manipulation, and navigation tasks. The Perceptive Workbench has been used for a variety of applications, including augmented reality gaming and terrain navigation. This paper focuses on the techniques used in implementing the Perceptive Workbench and the system's performance.     

Microstructural modifications in a dynamically consolidated microcrystalline nickel titanium alloy powder

Spherically shaped, microcrystalline NiTi alloy powder with both nonhomogeneous particle-size distribution (2 to 60m diameter) and chemical composition, was consolidated with a shock input energy of 316 kJ kg^–1. Upon shock compaction, the two-phase NiTi powder particles (containing 45wt% Ti and 65 wt% Ti) were bonded together, generally by interparticle melting and subsequent welding. The melted material at interparticle regions was observed to have rapidly solidified to largely amorphous and/or microcrystalline phases. Particle interiors were also subjected to extensive plastic deformation which resulted in deformation twinning, grain elongation and some recrystallization to defect-free grains. Unique microstructural modifications occurring due to inhomogeneous thermal and mechanical processing during the dynamic consolidation process, are reported here.     

Detection and tracking of the backreflection of potassium dihydrogen phosphate images in the presence or absence of a phase mask

The potassium dihydrogen phosphate (KDP) crystals present in the final optics assembly at the National Ignition Facility (NIF) are used for conversion of an infrared laser light beam into an ultraviolet beam. The conversion is highest for a certain incident angle, the alignment of which is determined from the position of the backreflection beam, which exhibits a distinct characteristic shape. When a phase-plate device is introduced before the final assembly to increase the uniformity of the beam, the backreflection pattern changes drastically. The algorithm that is best for tracking the special-shaped beam is no longer suitable for tracking the phase-modified beam. We discuss our detection schemes for both situations. In particular, we demonstrate how the algorithm senses the modified beam by using a newly proposed criterion of correlation peak pedestal area and executes an alternate algorithm in real time without operator intervention. This new algorithm continuously tracks the beam pattern to guarantee reliable and repeatable sensing. Results from simulation and real-world implementation of the algorithm at the NIF facility are presented.