Fast-fission tokamak breeder reactors

A fast-fission blanket around a fusion plasma exploits high neutron multiplication for superior breeding and high-energy multiplication to generate significant net electrical power. A major improvement over previous fast-fission blanket concepts is the use of mobile fuel, namely a pebble-bed configuration with helium cooling. Upon loss of coolant, the mobile fuel can be gravity-dumped to a separately cooled dump tank before excessive temperatures are reached. The pebble bed is also compatible with rapid fuel exchange and a low-cost reprocessing method. With the ignited tokamak plasma producing 620 MW of fusion power, the net electric power is 1600 MW_e and the annual fissile production exceeds 3 tonnes.     

Derivatization of Preformed Polymers to Produce Ceramic Precursors

The feasibility of producing derivatized preformed polymers to be used as ceramic precursors was explored. A borane derivative of polyethyleneimine (PEI) was prepared through a transamination reaction involving Me₃NBH₃. Higher boron loadings were possible with Me₃NB₃H₇. The borane derivative could be cast into films and produced boron nitride upon pyrolysis. Similarly, polyethyleneimine hydrochloride was converted into the cyanohydroborate derivative through a reaction with NaBH₃CN. This derivative was also accessible through a transamination reaction. Both materials produced boron nitride upon pyrolysis. Polyallylamine hydrochloride could not be derivatized. Silyl derivatives of PEI were also prepared, but the products obtained afforded low ceramic yields upon pyrolysis.     

Milling procedures and air classification of amaranth flours

The different milling characteristics of Amaranthus cruentus, a domestic variety prevailing in Mexico, selected as representative sample, are herein discussed. This was subjected to proximate analysis, which confirmed its good quality. Milling trials were carried out for the preparation of whole flour by means of conventional mills and by combining some of these with the Raymond and Alpine separators for air classification. Results were then compared to those obtained with a Strong-Scott pearler. Grits and bran contained the highest protein concentration. After comparing overall results, it may be concluded that the best operating conditions are the following: a) seed pearling using five passes, in a pearler, with variable yields of approximately 22% containing 36% protein, and b) combining the Miag mill and Raymond air separator, with variable yields of approximately 32% and a protein content of 30-36%. Proximate analysis of the fractions as well as farinographic and amylographic characteristics--different from those of whole wheat and amaranth flours--suggest their use in the preparation of nutritionally-enriched food products.     

An introduction to object-oriented programming with a didactic microworld: objectKarel

The objects-first strategy to teaching programming has prevailed over the imperative-first and functional-first strategies during the last decade. However, the objects-first strategy has created added difficulties to both the teaching and learning of programming. In an attempt to confront these difficulties and support the objects-first strategy we developed a novel programming environment, objectKarel, which uses the language Karel++. The design of objectKarel was based on the results of the extended research that has been carried out about novice programmers. What differentiates it from analogous environments is the fact that it combines features that have been used solely in them: incorporated e-lessons and hands-on activities; an easy to use structure editor for developing/editing programs; program animation; explanatory visualization; highly informative and friendly error messages; recordability. In this paper, we present the didactic rationale that dictated the design of objectKarel and the features of the environment, including the e-lessons. In addition, we present the results from the use of objectKarel in the classroom and the results of the students’ assessment of the environment.     

A reconfigurable computing framework for multi-scale cellular image processing

Cellular computing architectures represent an important class of computation that are characterized by simple processing elements, local interconnect and massive parallelism. These architectures are a good match for many image and video processing applications and can be substantially accelerated with Reconfigurable Computers. We present a flexible software/hardware framework for design, implementation and automatic synthesis of cellular image processing algorithms. The system provides an extremely flexible set of parallel, pipelined and time-multiplexed components which can be tailored through reconfigurable hardware for particular applications. The most novel aspects of our framework include a highly pipelined architecture for multi-scale cellular image processing as well as support for several different pattern recognition applications. In this paper, we will describe the system in detail and present our performance assessments. The system achieved speed-up of at least 100× for computationally expensive sub-problems and 10× for end-to-end applications compared to software implementations.     

Business or pleasure? Utilitarian versus hedonic considerations in emotion regulation.

It is widely accepted that emotions have utilitarian as well as hedonic consequences. Nevertheless, it is typically assumed that individuals regulate emotions to obtain hedonic, rather than utilitarian, benefits. In this study, the authors tested whether individuals represent the utility of pleasant and unpleasant emotions and whether they would be motivated to experience unpleasant emotions if they believed they could be useful. First, findings revealed that participants explicitly viewed approach emotions (e.g., excitement) as useful for obtaining rewards, but viewed avoidance emotions (e.g., worry) as useful for avoiding threats. Second, this pattern was replicated in implicit representations of emotional utility, which were dissociated from explicit ones. Third, implicit, but not explicit, representations of emotional utility predicted motives for emotion regulation. When anticipating a threatening task, participants who viewed emotions such as worry and fear as useful for avoiding threats preferred to engage in activities that were likely to increase worry and fear (vs. excitement) before the task. These findings demonstrate that utilitarian considerations play an important, if underappreciated, role in emotion regulation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

From product documentation to a ‘method prototype’ and standard times: a new technique for complex manual assembly

This paper suggests a new technique to facilitate consistent transition between planning and production stages of small lots of complex products (in quantities that do not justify full automation). Despite the usage of modern approaches such as design for assembly and design for manufacturing the typical product planning ends up before production planning begins, instead of having a unified seamless planning process. This paper presents a new three stage technique to fill the gap between product planning and production. The paper shows how to generate a rigorous production plan by: (1) extending the Bill-of-Materials to include additional required information, (2) constructing an assembly ‘method prototype’ and (3) using the ‘method prototype’ to calculate time standards for executing the assembly. A case study illustrates the proposed technique.