Structural Engineering with NiTi. I: Basic Materials Characterization

The overarching goal of this two-part paper is to provide a more unified understanding of NiTi shape memory alloys intended for use in structural engineering applications. Here, we present results from basic materials characterization of large diameter polycrystalline NiTi bars. Deformation processed bars with diameters of 12.7, 19.1, and 31.8?mm and various heat treatments were characterized at multiple length scales. Transmission electron microscopy revealed a nanometer scale precipitate structure present in the heat-treated, but not as-received bars. Spatial crystallographic texture measurements performed with electron backscatter diffraction, reveal a 〈111〉 texture along the longitudinal bar drawing axis in the majority of the bar, with a secondary longitudinal 〈110〉 component near the center of the bars. The prominence of the 〈110〉 texture increases with decreasing bar diameter or increasing percentage of deformation processing. Transformation temperatures and hardness were measured on samples extracted from the bars and are shown to depend strongly on bar heat treatment, but not bar diameter. The fine coherent precipitate structure induced during low temperature aging places transformation temperatures in the pseudoelastic range at room temperature and can be used to tailor material hardness.     

Chemical supply chain network optimization

Chemical supply chain networks provide large opportunities for cost reductions through the redesign of the flow of material from producer to customer. In this paper we present a mixed-integer linear program (MILP) capable of optimizing a multi-product supply chain network made up of production sites, an arbitrary number of echelons of distribution centers, and customer sites. The emphasis of our approach is on the redesign of existing supply chain networks. The model does not lump customer demand into zones, but rather deals with individual customer demand to directly address customer preferred mode of transport at each location. Historical records can be used to fix decision variables in the model so that a base case can be computed to validate the model and contrast it against the optimized network. The details inherent in this approach allow the optimization results to be partitioned and prioritized for implementation. The model results are processed to assign cost components to individual customer records. A simple case study is presented to illustrate the method and actual industrial results are reviewed.     

Public mental health: The role of population-based and macrosystems interventions in the wake of Hurricane Katrina.

Policy makers and decision makers are struggling to recognize the needs of shattered communities in the wake of unimaginable devastation. Professional psychology is providing some of the answers as it examines the consequences of disaster. The authors, 6 U.S. Public Health Service commissioned officers, describe their experiences in this new arena. Working at the federal, state, and local levels of government during the national response to the Hurricane Katrina disaster, the authors strive to identify high-value practice areas and define new roles for professional psychologists. The authors suggest that traditional crisis and trauma interventions are expanding to include nontraditional population-based and macrosystems-level interventions. Such roles are explored in narrative form, providing professional and personal insight into the impact that psychologists can have on decision makers who recognize their value and position them effectively. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Psychology's reality debate: A "levels of reality" approach.

For different reasons, some modern and postmodern psychologists are skeptical about the reality of psychological phenomena as irreducible, influential entities. Nonetheless, much psychological inquiry presumes precisely such a reality. The authors present a "levels of reality" approach to psychological reality that they believe can assuage some of the concerns of psychological skeptics. This approach treats psychological reality as inseparably embedded in sociocultural, biological, and physical levels of reality, without being reducible to any of these other levels. The authors develop their "levels of reality" approach in relation to four different doctrines of realism, and elaborate its implications for understanding psychological phenomena. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Using a Virtual Body to Aid in Exergaming System Development

A framework for simulating physiological responses to exercise lets exergame developers more efficiently test their games during development. An example implementation combines software that simulates heart-rate responses with a custom hardware setup. Simulated heart-rate responses closely match the real physiological responses, demonstrating the approach's validity and potential.     

Sinterbonding cobalt-cemented tungsten carbide to tungsten heavy alloys

Cobalt-cemented tungsten carbide (WC–Co) powder was sinterbonded to nickel–iron tungsten heavy alloy (WHA) for use in high-temperature tooling applications. Sinterbonding was performed under various conditions, including changes to the sintering conditions and initial WHA material forms, to determine various processing conditions that yield a consolidated interface indicative of a high degree of bonding. Sinterbonding WC–Co to fully dense WHA bar stock yielded a consolidated interface comprised primarily of complex η-carbides. Defects at the interface, including voids, microcracking, and porosity were the result of other sinterbonding processing conditions explored in this work. Co-rich η-carbides were found to form at the interface in every condition examined. A thermodynamic evaluation of η-carbides as a function of carbon activity determined that Co-rich η-carbides formed preferentially in regions of low carbon activity. The predicted thermodynamic trends are in agreement with interfacial microstructural observations.     

Selecting the best system when systems are revealed sequentially

Statistical Ranking and Selection (R&S) is a collection of experiment design and analysis techniques for selecting the system with the largest or smallest mean performance from among a finite set of alternatives. R&S procedures have received considerable research attention in the stochastic simulation community, and they have been incorporated in commercial simulation software. All existing procedures assume that the set of alternatives is available at the beginning of the experiment. In many situations, however, the alternatives are revealed (generated) sequentially during the experiment. We introduce procedures that are capable of selecting the best alternative in these situations and provide the desired statistical guarantees.