CADRE: An Asynchronous Embedded DSP for Mobile Phone Applications

Asynchronous design techniques have a number of compelling features that make them suited for complex system on chip designs. However, it is necessary to develop practical and efficient design techniques to overcome the present shortage of commercial design tools. This paper describes the development of CADRE (Configurable Asynchronous DSP for Reduced Energy), a 750K transistor, high performance, low-power digital signal processor IP block intended for digital mobile phone chipsets. A short time period was available for the project, and so a methodology was developed that allowed high-level simulation of the design at the earliest possible stage within the conventional schematic entry environment and simulation tools used for later circuit-level performance and power consumption assessment. Initial modeling was based on C behavioral models of the various data and control components, with the many asynchronous control circuits required automatically generated from their specifications. This has enabled design options to be explored and unusual features of the design, such as the Register Bank which is designed to exploit data access patterns, are presented along with the power and performance results of the processor as a whole.     

Growth of masking as a measure of response growth in hearing-impaired listeners

Growth-of-masking functions were obtained from 19 normal and 5 hearing-impaired listeners using a simultaneous-masking paradigm. When masker and probe frequency are identical, the slope of masking approximates 1.0 for both normal-hearing and impaired listeners. For masker frequencies less than or greater than probe frequency, the slopes for impaired listeners are shallower than those of normals. These findings are consistent with previously reported physiological data (single-fiber rate versus level and AP masking functions) for animals with induced cochlear lesions. Results are discussed in terms of a potential masking technique to estimate the growth of response in normal and impaired ears.     

Derived Lengths of Solvable Groups Having Five Irreducible Character Degrees II

Let G be a solvable group with five character degrees. Suppose that there is some prime p so that G/O ^p (G) is not Abelian. Also, assume that cd(G) contains a degree that is not divisible by p. Under these hypotheses, we show that the derived length of G is at most 4.     

Preservice Elementary Teachers' Use of Mathematics in a Project‐Based Science Approach

The use of a project‐based science (PBS) approach to teaching encourages students to integrate mathematics and science in meaningful ways as they create projects. As a beginning study of how students use mathematics in such an approach, an analysis of 23 projects developed by preservice elementary teachers enrolled in an elementary science course was conducted. Findings showed that students made a number of different types of mathematical errors and underutilized data representation and summary forms. Implications included the importance of developing methods for supporting the use of mathematical tools in utilizing a project‐based approach and considering ways that such tools mediate scientific thinking.     

Metaheuristics can solve sudoku puzzles

In this paper we present, to our knowledge, the first application of a metaheuristic technique to the very popular and NP-complete puzzle known as ‘sudoku’. We see that this stochastic search-based algorithm, which uses simulated annealing, is able to complete logic-solvable puzzle-instances that feature daily in many of the UK’s national newspapers. We also introduce a new method for producing sudoku problem instances (that are not necessarily logic-solvable) and use this together with the proposed SA algorithm to try and discover for what types of instances this algorithm is best suited. Consequently we notice the presence of an ‘easy-hard-easy’ style phase-transition similar to other problems encountered in operational research.     

A transportable gamma spectroscopy system applied to the measurement of fission products

Normally, gamma-ray spectroscopy is performed by equipment positioned in the SLOWPOKE-2 Facility at the Royal Military College; however, there have occasionally been requirements for analyses externally. A transportable gamma spectroscopy system was thus assembled by acquiring a commercially available multichannel analyzer, analysis program and detector, and by designing and constructing a transportable shielding castle. It was then used to take measurements of fission product concentrations at several research reactors.     

Current methods for site-directed structure generation

Summary There has been a rapid growth of interest in techniques for site-directed drug design, fuelled by the increasing availability of structural models of proteins of therapeutic importance, and by studies reported in the literature showing that potent chemical leads can be obtained by these techniques. Structure generation programs offer the prospect of discovering highly original lead structures from novel chemical families. Due to the fact that this technique is more-or-less still in its infancy, there are no case studies available that demonstrate the use of structure generation programs for site-directed drug design. Such programs were first proposed in 1986, and became commercially available in early 1992. They have shown their ability to reproduce, or suggest reasonable alternatives for, ligands in well-defined binding sites. This brief review will discuss the recent advances that have been made in the field of site-directed structure generation.     

Load-capacity interference and the bathtub curve

Load-capacity (stress-strength) interference theory is used to derive a heuristic failure rate for an item subjected to repetitive loading which is Poisson distributed in time. Numerical calculations are performed using Gaussian distributions in load and capacity. Infant mortality, constant failure rate (Poisson failures), and aging are shown to be associated with capacity variability, load variability, and capacity deterioration, respectively. Bathtub-shaped failure rate curves are obtained when all three failure types are present. Changes in load or capacity distribution parameters often strongly affect the quantitative behavior of the failure-rate curves, but they do not affect the qualitative behavior of the bathtub curve. Neither is it likely that the qualitative behavior will be affected by the use of nonGaussian distributions. The numerical results, however, indicate that infant mortality and wear-out failures interact strongly with load variability. Thus bathtub curves arising from this model cannot be represented as simple superpositions of independent contributions from the three failure types. Only if the three failure types arise from independent failure mechanisms or in different components is it legitimate simply to sum the failure rate contributions     

Solution of nonlinear kinematics of a parallel-link constrained Stewart platform manipulator

The Stewart platform manipulator is a fully parallel kinematic linkage system that has great advantages over typical serial link robots. However, one major problem in controlling this kind of manipulator is that, due to its closed kinematic chain and parallel-link constrained structure, it is impossible to derive an explicit kinematic solution. This paper proposes a simplified algorithm to numerically solve the forward kinematics of a six-links Stewart platform. Taking advantage of some fundamental geometric operations, the proposed algorithm involves only 3 nonlinear simultaneous equations. The explicit expressions are derived for some special configurations which can directly give the geometric limitations to motion in terms of the geometric dimensions of the platforms and the legs.Research was supported by Texas Advanced Technology program under grant 003656-008 and National Science Foundation under grant MSS9211970.