Predicting the Spinel–Nepheline Liquidus for Application to Nuclear Waste Glass Processing. Part II: Quasicrystalline Freezing Point Depression Model

The crystal-melt equilibria in complex 15-component-simulated high-level waste (HLW) glass melts are modeled based on quasicrystalline concepts that are discussed in Part I. A pseudobinary phase diagram between a transition metal ferrite spinel (an incongruent melt product of a transition metal iron-rich acmite) and nepheline is defined based on calculation of the quasicrystalline melt precursors calculated by a freezing point depression approach. The pseudobinary lies within the Al₂O₃–Fe₂O₃–Na₂O–SiO₂ quaternary system that defines the crystallization of basalt glass melts. The modeling provides the partitioning of species between the melt and the primary liquidus phases. The medium-range order of the melt and the melt-crystal exchange equilibria are defined based on a constrained mathematical treatment that considers the crystallochemical coordination of the elemental species in acmite and nepheline. The liquidus phases that form are shown to be governed by the melt polymerization (Part II) and the thermodynamic octahedral site preference energies (Part I). The liquidus model developed based on these concepts has been used to prevent unwanted crystallization in the world's largest HLW melter for the past 4 years while allowing >10 wt% higher waste loadings to be processed.     

The bogus pipeline revisited: The use of the threat of detection as a means of increasing self-reports of tobacco use.

Reexamined the use of the bogus pipeline (biological monitoring) as a means of enhancing self-reports of cigarette smoking among 541 9th and 1,100 8th graders who had been previously questioned and tested concerning tobacco use. Ss were either put under the bogus pipeline condition through the concurrent collection of saliva and questionnaire data or were not put under this condition and simply completed the questionnaire with normal guarantees of confidentiality. Predicted differences in self-reports between groups were not observed. Overall, Ss who were asked to provide specimens reacted negatively to the biological monitoring, with a sizable proportion refusing to participate. The value of the bogus pipeline as a technique for increasing the accuracy of self-reports among older and previously tested adolescents is questioned. (9 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Use of Nitrogen Dioxide to Improve the Superconducting Properties of YBa2Cu3O7

The elemental homogeneity of YBa₂Cu₃O₇ powders can be improved substantially by heating the powder in a nitrogen dioxide-containing atmosphere (e.g., 950°C), followed by annealing in oxygen above 750°C, and slow cooling to room temperature. The improved homogeneity results in a substantially larger flux exclusion signal for the NO₂-treated powder, as measured by ac susceptibility. Moreover, the NO₂-processed powder exhibits a slablike morphology which should be more suitable for grain alignment. A substantial advantage of the NO₂ process is that this process is easily scaled to larger batches and the results are highly reproducible. This is not the case for solid-state reaction processes requiring repeated heating and grinding. The experimental results suggest a mechanism which involves the formation of a small amount of molten Ba(NO₃)₂ which acts as a flux that dissolves the constituents and reprecipitates them as highpurity YBa₂Cu₃O₇. The effects of the various process variables on the properties of the treated powder, and the reproducibility of the process, are discussed.     

An adaptive numerical integration code for a chain of transputers

We consider the calculation of ∫_a^bƒ(x)dx, on a linear chain of transputers of arbitrary length, in which each transputer calculates an approximation to this integral on a subinterval of equal length using an adaptive method based on the ten point Gaussain rule and the twenty-one point Kronrod extension. Extensive numerical testing on a chain of 32 T800s shows that if a large number of function evaluations are needed then linear speed-ups are achievable with any number of transputers.     

Hypnotic blindness and the relevance of cognitive style.

Real, hypnotized and simulating, unhypnotized subjects were instructed to use either a constructive or a concentrative cognitive style when attempting to respond to a suggestion for hypnotic blindness; also, some subjects were administered the suggestion without any instructions about cognitive style. More reals who received the constructive rather than the concentrative instructions reported complete blindness; a similar number of simulators who received the different instructions reported complete blindness. Moreover, reals who received the constructive instructions reported a more rapidly developed belief in their blindness. The findings are discussed in terms of the relevance of cognitive style to subjects' reports of hypnotic blindness, and the possibility is considered that both reports of and belief in hypnotic blindness are determined in part by cognitive style. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Employee reactions to contextual and session components of performance appraisal.

A neglected area of performance appraisal research concerns the context within which the appraisal process occurs. For a sample of exempt employees, measures were developed that assessed system components of the appraisal context. The contribution of these variables (complexity, implementation, and follow-up) to the prediction of 2 measures of employee reactions to performance appraisal (review session satisfaction and appraisal system satisfaction) was compared with the contribution of a more frequently studied set of variables—supervisory behaviors in the review session. The relationship of a salary linkage variable to the 2 outcome criteria also was assessed. The supervisory session variables were related to session satisfaction, and the system contextual variables were primarily related to system satisfaction. Salary linkage was associated with system satisfaction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Controlling free flight of a robotic fly using an onboard vision sensor inspired by insect ocelli

Scaling a flying robot down to the size of a fly or bee requires advances in manufacturing, sensing and control, and will provide insights into mechanisms used by their biological counterparts. Controlled flight at this scale has previously required external cameras to provide the feedback to regulate the continuous corrective manoeuvres necessary to keep the unstable robot from tumbling. One stabilization mechanism used by flying insects may be to sense the horizon or Sun using the ocelli, a set of three light sensors distinct from the compound eyes. Here, we present an ocelli-inspired visual sensor and use it to stabilize a fly-sized robot. We propose a feedback controller that applies torque in proportion to the angular velocity of the source of light estimated by the ocelli. We demonstrate theoretically and empirically that this is sufficient to stabilize the robot''s upright orientation. This constitutes the first known use of onboard sensors at this scale. Dipteran flies use halteres to provide gyroscopic velocity feedback, but it is unknown how other insects such as honeybees stabilize flight without these sensory organs. Our results, using a vehicle of similar size and dynamics to the honeybee, suggest how the ocelli could serve this role.     

Optical Measurement of Peak Air Shock Pressures Following Explosions

High speed video and streak camera imaging are used to measure peak pressures for explosions of spherical charges of the high explosive C‐4 (92 % trimethylenetrinitramine, C₃H₆N₆O₆). The technique measures the velocity of the air shock produced by the detonation of the explosive charges, converts this velocity to a Mach number, and uses the Mach number to determine a peak shock pressure. Peak pressure measurements are reported from a few millimeters to approximately one meter from the charge surface. Optical peak pressure measurements are compared to peak pressures measured using piezoelectric pressure transducers, and to peak pressure measurements estimated using the blast computer code CONWEP. A discussion of accuracy of peak pressures determined optically is provided.     

Design,fabrication, and analysis of transparent silicon solar cells for multi‐junction assemblies

Transparent silicon solar cells can lead to an increased efficiency of silicon‐based multi‐junction assemblies by transmitting near and below band gap energy light for conversion in a low band gap solar cell. This analysis shows that the maximum efficiency gain for a low band gap solar cell beneath silicon at a concentration of 50 suns is 5.8%, based on ideal absorption and conversion of the photons. This work analyzes the trade‐offs between increased near band edge absorption in the silicon and silicon solar cell transparency. Application of these results to real cases including a germanium bottom solar cell is analyzed, leading to a range of cases with increased system efficiency. Non‐ideal surfaces and real silicon and germanium solar cell device performance are presented. The range of practical system gains may be as low as 2.2 – 1% absolute when compared with the efficiency of a light‐trapped silicon solar cell for 1‐sun operation, based on this work. Copyright © 2012 John Wiley & Sons, Ltd.     

Cooperative aspect-oriented programming

Aspect-oriented programming (AOP) seeks to improve software modularity via the separation of cross-cutting concerns. AOP proponents often advocate a development strategy where programmers write the main application (base code), ignoring cross-cutting concerns, and then aspect programmers, domain experts in their specific concerns, weave in the logic for these more specialized cross-cutting concerns. This purely oblivious strategy, however, has empirically been shown to tightly couple aspects to base code in many cases, hindering aspect modularity and reuse. In essence, the more intricate the weaving between the cross-cutting concern and the base code (lexically and/or semantically), the harder it becomes to: (a) robustly specify how to weave the aspects in at the required points, (b) capture interactions between aspects and base code, and (c) preserve the correct weaving as the base code evolves.We propose an alternate methodology, termed cooperative aspect-oriented programming (Co-AOP), where complete lexical separation of concerns is not taken as an absolute requirement. Instead, cross-cutting concerns are explicitly modeled as abstract interfaces through explicit join points (EJPs). Programmers specify where these interfaces interact with base code either through explicit lexical references or via traditional oblivious aspects. This explicit awareness allows base code and aspects to cooperate in ways that were previously not possible: arbitrary blocks of code can be advised, advice can be explicitly parameterized, base code can guide aspects in where to apply advice, and aspects can statically enforce new constraints upon the base code that they advise. These new techniques allow aspect modularity and program safety to increase, and bring us towards a cooperative AOP paradigm.We illustrate our methodology via an example on transactions, and also give an initial evaluation of cooperative AOP through an empirical study on program extensibility comparing both the traditional and cooperative AOP methodologies. Initial results show that cooperative AOP techniques result in code that is less complex with lower overall coupling, facilitating extensibility.