EFFECT OF STORAGE CONDITIONS ON WEATHERING OF COMMERCIAL GLASS CONTAINERS*

Important factors in the weathering of commercial flint glass containers were determined by the storage of empty bottles, capped and uncapped, of ten different compositions for periods up to thirteen months at (1) 100°F., 80% relative humidity, (2) 12OoF., 15% relative humidity, and (3) normal room conditions. The effect of storage was determined by visual inspection, tests of the alkali extraction by water at elevated temperatures and photomicrographs of the weathered surfaces. The results obtained indicate that the most important factor in the weathering conditions used is the humidity. Although the weathering produced depends on several factors, the important weathering effect of high humidity may be significantly controlled by the chemical composition of the glass. Storage for the periods used at low relative humidity or at normal room conditions was relatively ineffective for weathering any of the bottles tested. Photomicrographs of representative weathered internal and external bottle surfaces are shown. A microscopic examination of these surfaces revealed the presence of calcite     

Tables for boundary-layer thicknesses of similar compressible laminar flow

Similarity solution of the compressible, laminar boundary-layer equation depends on pressure gradient parameter β and wall to inviscid stagnation temperature ratiog _w . However, the derived quantities, such as various thicknesses, also depend on speed parameter S, thereby requiring three dimensional tables for the tabulated results. A new formulation is provided that enables all quantities of interest to be determined by the two-dimensional tables in which β andg _w are the input parameters. With such a set, accurate values can be found for the skin-friction coefficient, Stanton number, and the five most common viscous and thermal boundary-layer thicknesses for arbitrary values of the speed parameter. A comprehensive set of tables is provided in which β ranges from its separation value to 100 andg _w ranges 0 to 5. Quasi-linearization method is applied to the governing equations and generalized Newton-Raphson method is used to obtain successive initial condition. As a result computation time is reduced significantly.     

Rolling Bearing Service Life Based on Probable Cause for Removal—A Tutorial

In 1947 and 1952 G. Lundberg and A. Palmgren developed what is now referred to as the Lundberg-Palmgren model for rolling bearing life prediction based on classical rolling-element fatigue. Today, bearing fatigue probably accounts for less than 5% of bearings removed from service for cause. A bearing service life prediction methodology and tutorial indexed to eight probable causes for bearing removal, including fatigue, are presented that incorporate strict series reliability; Weibull statistical analysis; available published field data from the Naval Air Rework Facility; and ～224,000 rolling-element bearings removed for rework from commercial aircraft engines. Bearing service life L_serv can be benchmarked and calculated to the bearing L₁₀ fatigue life as follows: L_serv = X^1/m L₁₀, where X is the number of bearings removed from service because of fatigue divided by the total of all bearings removed from service regardless of cause and m is the Weibull modulus of the bearings removed from service. The most conservative bearing L₁₀ service life calculation is obtained assuming an exponential distribution where m = 1.1. Of the ～224,000 commercial engine bearings removed from service for rework, 1,977 or 0.88% were rejected because of fatigue. From the Naval Air Rework Facility bearing data, eliminating rolling–element fatigue as a cause for removal, the L₁₀ service life of these bearings would increase by approximately 3%.     

Improving Learning in First‐Year Engineering Courses through Interdisciplinary Collaborative Assessment

This paper describes a feedback process that assessed first‐year engineering student learning using a mastery exam. The results were used to improve learning and teaching in first‐year courses. To design the initial exam, basic knowledge and concepts were identified by instructors from each of the host departments (Chemistry, Math, Physics and Computer Science). In 2004, the 45‐item exam was administered to 191 second‐year engineering students, and in September 2005, the revised exam was administered to the next class of second‐year engineering students. The exam was analyzed using Item Response Theory (IRT) to determine student abilities in each subject area tested. Between exam administrations, workshops were conducted with the four department instructor groups to present exam results and discuss teaching issues. The exam provided a learning assessment mechanism that can be used to engage faculty in science, mathematics, and engineering in productive linkages for continual improvement to curriculum.     

The P300 as an electrophysiological probe of alcohol expectancy.

Language-based measures indicate that alcohol expectancies influence alcohol consumption. To relate these measures to brain actions that precede verbal output, the P300 component of the Event-related potentials (ERPs) was used to detect violations of individually held alcohol expectancies. As predicted, P300 amplitude elicited by negative alcohol expectancy stimuli was positively correlated with endorsement of positive/arousing alcohol expectancies on the language-based measures, such that the higher an individual's positive/arousing expectancies, the larger was the P300 elicited by negative alcohol expectancy stimuli. These results demonstrated concordance between language-based measures of alcohol expectancies and electrophysiological probes of expectancy. While it remains unknown whether these expectancy processes are integral to decision pathways that influence consumption, these findings suggest that such processing can occur very quickly outside of conscious deliberation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Probabilistic inference of multijoint movements, skeletal parameters and marker attachments from diverse motion capture data

This paper describes a comprehensive solution to the problem of reconstructing the multijoint movement trajectories of the human body from diverse motion capture data. The problem is formulated in a probabilistic framework so as to handle multiple and unavoidable sources of uncertainty: sensor noise, soft tissue deformation and marker slip, inaccurate marker placement and limb measurement, and missing data due to occlusions. All unknown quantities are treated as state variables even though some of them are constant. In this way, state estimation and system identification can be performed simultaneously, obtaining not only the most likely values but also the confidence intervals of the joint angles, skeletal parameters, and marker positions and orientations relative to the limb segments. The inference method is a Gauss-Newton generalization of the extended Kalman filter. It is adapted to the kinematic domain by expressing spatial rotations via quaternions and computing the sensor residuals and their Jacobians analytically. The ultimate goal of this project is to provide a reliable data analysis tool used in practice. The software implementation is available online.     

Aberration-free superresolution imaging via binary speckle pattern encoding and processing

We present an approach that provides superresolution beyond the classical limit as well as image restoration in the presence of aberrations; in particular, the ability to obtain superresolution while extending the depth of field (DOF) simultaneously is tested experimentally. It is based on an approach, recently proposed, shown to increase the resolution significantly for in-focus images by speckle encoding and decoding. In our approach, an object multiplied by a fine binary speckle pattern may be located anywhere along an extended DOF region. Since the exact magnification is not known in the presence of defocus aberration, the acquired low-resolution image is electronically processed via a parallel-branch decoding scheme, where in each branch the image is multiplied by the same high-resolution synchronized time-varying binary speckle but with different magnification. Finally, a hard-decision algorithm chooses the branch that provides the highest-resolution output image, thus achieving insensitivity to aberrations as well as DOF variations. Simulation as well as experimental results are presented, exhibiting significant resolution improvement factors.     

A better approach to goodness: Reply to Wagemans (1999).

In P. A. van der Helm and E. L. J. Leeuwenberg (see record 1996-01780-002), the authors presented a representation model for the goodness, or detectability, of visual regularities such as mirror symmetry and repetition. J. Wagemans (see record 1999-03499-009) acknowledged that this holographic goodness model has considerable explanatory power, but he also argued that it is not good enough yet. He challenged van der Helm and Leeuwenberg to qualify some open ends of their representation model, in particular those concerning its process assumptions. He also questioned the authors' assessment of previous goodness accounts such as S. E. Palmer's (1982, 1983) transformational approach and his own bootstrap model. He concluded that it is expedient to aim at a synthesis of useful aspects of diverse accounts of goodness, but he did not establish such a synthesis. Van der Helm and Leeuwenberg agree with his conclusion that such a synthesis is a worthy cause, but they disagree with his evaluation of the issues involved. This article is a reply with an alternative evaluation of these issues, advancing the discussion to a process-representation synthesis called holographic bootstrapping. (PsycINFO Database Record (c) 2010 APA, all rights reserved)