Photoelastic Measurement of High Stress Profiles in Ion-Exchanged Glass

Photoelastic fringes were directly measured to fully characterize high magnitude, steep compressive stress gradients in an ion-exchanged glass, trade named Ion-Armor™. Initially, using a thick (9.9 mm) rectangular bar and circular polariscope arrangement the overall residual stress profile in a bulk specimen was determined. However, due to the relatively large thickness of the specimen, the high density of fringes (steep stress gradient) close to the edge of the specimen became too diffused to allow an accurate count of fringe order. A thinner (0.71 mm) specimen was then used along with a polarizing light microscope to enhance the fringe contrast. This arrangement yielded approximately four isochromatic fringes, representing a maximum surface compressive stress of 984 MPa, which rapidly decreased to ~300 MPa within 25 μm depth from the strengthened surface. Also, the case-depth of the ion-exchange process was found to be 0.8 mm. Thus, the technique was able to directly capture the extremely high residual compressive stresses generated in an ion-exchanged glass. The current technique utilized for residual stress measurement is more objective and straightforward to implement than what is specified in ASTM standard C-1422, particularly for those specimens having steep stress gradients just below the strengthened surface.     

Postmodern sandplay: An introduction for play therapists.

In this article we apply postmodern insights to sandplay therapy. In doing so, we seek to move sandplay therapy from its traditional base of an endeavor at problem solving: a therapeutic method to aid one's diagnosis and address concerns over functioning. Rather, we offer an approach to sandplay therapy from a base of postmodern thought. As has been done in the field of family therapy with solution-building therapy (De Jong & Berg, 2002) and narrative therapy (White, 2007), postmodern insights transform this therapeutic method into a narrative endeavor concerned with the articulation of identity as the means to foster change in the client. Sandplay offers a safe and secure site where the articulation of this new, empowered identity begins to get crafted. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Uranium Exploration in the United States

The United States Atomic Energy Commission looks to the private prospector and the mining industry to assure the success of our uranium exploration program. We believe that industry is certain to increase its activity in the field rapidly as the economic importance of uranium to its operations is more fully realized. The contribution made by educational institutions and by other government agencies in developing and distributing information is recognized by the Commission as an important phase of the program.

Progress is being made in the discovery of ore and the development of ore-finding techniques on the Colorado Plateau, which is the most important uranium-producing region in the United States. Other areas of primary and secondary uranium mineralization, such as the Colorado Front Range, the newly discovered deposits in the Sunshine Mine in Idaho, the Marysvale, Utah, area, and the Upper Peninsula of Michigan, show promise for future production. Evaluation of potential low-grade uranium ores such as the phosphate rocks of Florida and the northwestern states, and the black shales of Tennessee and Kentucky, has been substantially completed.

The Commission's exploration program will, we believe, assure the United States of a growing supply of domestic uranium ore. Together with the results of the Canadian exploration activities, which are most encouraging, our program should provide increasing resources of this all-important material, and should further reduce our dependence on supplies from overseas.     

Industrial model predictive control technology as applied to continuous polymerization processes

This paper will review the progress to date concerning the application of the new Model Predictive Control (MPC) tools to a prototype continuous polymerization (CP) process. It will discuss in general why the MPC technology maybe a good fit for the CP control problems (minimize settling time after transition, multivariable interactions, unusual process dynamics). It will also discuss our experience with these tools.     

The kinetics of ettringite formation

Conversion of hemihydrate to gypsum, and ettringite formation in the system C₃A---CaSO₄·1/2H₂O---H₂O three hydration temperatures using x-ray diffraction. Analysis of the kinetics of gypsum formation suggests that the rate limiting step changes from an initial dependence on the hemihydrate surface area to a dependence on the gypsum growth rate. The formation of ettringite was found to be controlled by diffusion. In accord with the needle-like morphology that ettringite exhibits, a nucleation and growth model predicted one-dimensional growth. An apparent activation energy calculated for ettringite formation is consistent with a diffusionally controlled process.     

Pavlov's Bugs: Matching Repair Policies with Rewards

Software maintenance engineers devote a significant amount of work to repairing user-identified errors. But user, maintainer, and manager perceptions of an error's importance can vary, and bug-repair assignment policies can adversely affect those perceptions.     

Psychological influences on surgical recovery: Perspectives from psychoneuroimmunology.

Greater fear or distress prior to surgery is associated with a slower and more complicated postoperative recovery. Although anxiety presumably interferes with recuperation through both behavioral and physiological mechanisms, the pathways have been unclear. Recent work in psychoneuroimmunology (PNI) has demonstrated that stress delays wound healing. In addition, a second line of research has illustrated the adverse effects of pain on endocrine and immune function. A biobehavioral model is described that is based on these and other data; it suggests a number of routes through which psychological and behavioral responses can influence surgery and postsurgical outcomes. Clinical and research implications are highlighted. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Predicting individual differences in complex skill acquisition: Dynamics of ability determinants.

Addresses the controvervesy about ability determinants of individual differences in performance during and subsequent to skill acquisition. An information-processing examination of ability–performance relations during complex task acquisition is described. Included are ability testing (including general, reasoning, spatial, perceptual speed, and perceptual/psychomotor abilities) and skill acquisition over practice on the terminal radar approach controller simulation. Results validate and extend P. L. Ackerman's (1988) theory of cognitive ability determinants of individual differences in skill acquisition. Benefits of ability component and task component analyses over global analyses of ability–skill relations are demonstrated. Implications are discussed for selection instruments to predict air traffic controller success and for other tasks with inconsistent information-processing demands. (PsycINFO Database Record (c) 2010 APA, all rights reserved)