Recognition by directed attention to recursively partitioned images

A learning/recognition model (and instantiating program) is described which recursively combines the learning paradigms of conceptual clustering (Michalski, 1980) and learning-from-examples to resolve the ambiguities of real-world recognition. The model is based on neuropsychological and psychological evidence that the visual system is analytic, hierarchical, and composed of a parallel/serial dichotomy (many, see conclusions by Crick, 1984). Emulating the experimental evidence, parallel processes in the model decompose the image into components and cluster the constituents in much the same way as the image processing technique known as moment analysis (Alt, 1962). Serial, attentive mechanisms then reassemble the decompositions by investigating spatial relationships between components. The use of attentive mechanisms extends the moment analysis technique to handle alterations in structure and solves the contention problem created by combining the two learning paradigms. The contention results from a disagreement between the teacher and the model on what constitutes the salient features at the highest level of the symbol. There are four cases ZBT must handle, two of which result from the disagreement with the teacher. The parallel/serial dichotomy represents a vertical/horizontal tradeoff between the invariant and variant features of a domain. The resultant learned hierarchy allows ZBT to recognize structural differences while avoiding problems of exponential growth

Mechanism of shot peening enhancement for the fatigue performance of AA7050-T7451

Shot peening is a dynamic cold working process involving the impingement of peening media onto a substrate surface. Shot peening is commonly employed as a surface treatment technique within the aerospace industry during manufacturing, in order to improve fatigue performance of structural components. The compressive residual stress induced during shot peening is understood to result in fatigue crack growth retardation, improving the performance of shot peened components. However, shot peening is a compromise between the benefit of inducing a compressive residual stress and causing detrimental surface damage. Due to the relatively soft nature of AA7050-T7451, shot peening can result in cracking of the constituent particles, the effect of which is recognized as a ‘critically detrimental influence upon the component’s fatigue performance.’ The intention of this thesis is to understand the balance and fundamentals of these competing phenomena, through analysis involving a comparative study throughout the fatigue life cycle of ‘as manufactured’ versus shot peened AA7050-T7451. A series of dog bone samples were manufactured, with a subset undergoing shot peening surface treatment. Microstructural grain characterization and comparison of ‘as manufactured’ and shot peened AA7050-T7451 has been carried out using scanning electron microscope (SEM), electron back scatter diffraction (EBSD), and energy dispersive spectroscopy (EDS) techniques. A residual stress analysis through interrupted fatigue of ‘as manufactured’ and shot peened AA7050-T7451 was completed utilizing a combination of x-ray diffraction (XRD) and nano-indentation. The fatigue life cycle performance of the ‘as manufactured’ versus shot peened material has been evaluated, including qualitative analysis and comparison of crack initiation and propagation in ‘as manufactured’ and shot peened material. Through this experimentation and analysis, this thesis endeavors to answer the question of what is the mechanism for shot peening enhancement for fatigue performance. An objective of this work is to understand how a cracked particle starts to incubate the short crack into the matrix within a residual stress field

Integrated speech and morphological processing in a connectionist continuous speech understanding for Korean

A new tightly coupled speech and natural language integration model is presented for a TDNN-based continuous possibly large vocabulary speech recognition system for Korean. Unlike popular n-best techniques developed for integrating mainly HMM-based speech recognition and natural language processing in a {\em word level}, which is obviously inadequate for morphologically complex agglutinative languages, our model constructs a spoken language system based on a {\em morpheme-level} speech and language integration. With this integration scheme, the spoken Korean processing engine (SKOPE) is designed and implemented using a TDNN-based diphone recognition module integrated with a Viterbi-based lexical decoding and symbolic phonological/morphological co-analysis. Our experiment results show that the speaker-dependent continuous {\em eojeol} (Korean word) recognition and integrated morphological analysis can be achieved with over 80.6% success rate directly from speech inputs for the middle-level vocabularies.Comment: latex source with a4 style, 15 pages, to be published in computer processing of oriental language journa

Actor perception in business use case modeling

Mainstream literature recognizes the validity and effectiveness of use cases as a technique for gathering and capturing system requirements. Use cases represent the driver of various modern development methods, mainly of object-oriented extraction, such as the Unified Process. Although the adoption of use cases proliferated in the context of software systems development, they are not as extensively employed in business modeling . The concept of business use case is not a novelty, but only recently did it begin to re-circulate in the literature and in case tools. This paper examines the issues involved in adopting business use cases for capturing the functionality of an organization and proposes guidelines for their identification, packaging, and mapping to system use cases. The proposed guidelines are based on the principle of actor perception described in the paper. The application of this principle is exemplified with a worked example aimed at demonstrating the utility of the proposed guidelines and at clarifying the application of the principle of actor perception. The worked example is based on a series of workshops run at a major UK financial institution

Co-activation in the bilingual lexicon: Evidence from Chinese-English bilinguals

Investigation of the bilingual mental lexicon suggests that one of its defining characteristics is integration. Words across both languages are subject to parallel co-activation during language processing. An auditory stimulus typing task was used to assess connectivity on the basis of both morphology and phonology. English loanwords in Chinese and transparent English noun-noun compounds with Chinese translation equivalents with corresponding compound structure (corresponding compounds) were used as the critical stimuli. Accent was also manipulated to determine whether or not phonological cues may influence the degree of cross-linguistic co-activation. Results suggest cross-linguistic co-activation on the basis of phonological overlap in different script bilinguals but only weakly supported morphological integration in Chinese-English bilinguals. Accent led to greater co-activation of phonologically similar loanword pairs. Results are discussed in terms of inhibitory control, language acquisition, and the structure of the bilingual lexicon

Gradient-based optimization of non-linear structures and materials

Gradient-based optimization is a potent tool in many design processes today. It is particularly useful in industries where weight considerations are crucial, such as aerospace, but can also be exploited in for example civil engineering applications to reduce the material use and thereby the environmental impact. With the advent of advanced manufacture methods, it even possesses the potential to design novel materials with enhanced properties that naturally occurring materials lack. Unfortunately, most research on the subject often limits itself to linear problems, wherefore the optimization's utility in solving intricate non-linear problems is still comparatively rudimentary. The aim of this thesis is therefore to investigate gradient-based optimization of various non-linear structural problems, while addressing their inherent numerical and modeling complexities.This thesis contains an introduction to gradient-based optimization of non-linear structures and materials, involving both shape and topology optimization. To start, the governing equations of the macroscopic and microscopic problems are described. A multi-scale framework which details the transition between the scales is defined. A substantial part of the thesis is dedicated to eigenvalue problems in topology optimization, and the numerical issues that they accompany. Specifically, the effects of finite deformations on the topology optimized design taking into account eigenfrequencies, structural stability or elastic wave propagation are scrutinized. A fictitious domain approach to topology optimization is employed, wherein void regions are modeled via an ersatz material with low stiffness. Unfortunately, this brings about artificial eigenmodes and convergence problems in the finite element analyzes. Two methods which deal with both of the aforementioned problems are proposed, and their efficacy is illustrated via several numerical examples. The use of shape optimization to post-process topology optimized designs is investigated for problems where accurate boundary descriptions are crucial to capture the physics, as is the case in contact problems. To take this concept further, a simultaneous topology and shape optimization method is proposed, which allows parts of the structural boundaries to be modeled exactly up to numerical precision. This approach is proven to be especially useful in the design of pressure-driven soft robots

Simulation model of erosion and deposition on a barchan dune

Erosion and deposition over a barchan dune near the Salton Sea, California, are modeled by bookkeeping the quantity of sand in saltation following streamlines of transport. Field observations of near surface wind velocity and direction plus supplemental measurements of the velocity distribution over a scale model of the dune are combined as input to Bagnold type sand transport formulas corrected for slope effects. A unidirectional wind is assumed. The resulting patterns of erosion and deposition compare closely with those observed in the field and those predicted by the assumption of equilibrium (downwind translation of the dune without change in size or geometry). Discrepancies between the simulated results and the observed or predicted erosional patterns appear to be largely due to natural fluctuations in the wind direction. The shape of barchan dunes is a function of grain size, velocity, degree of saturation of the oncoming flow, and the variability in the direction of the oncoming wind. The size of the barchans may be controlled by natural atmospheric scales, by the age of the dunes, or by the upwind roughness. The upwind roughness can be controlled by fixed elements or by sand in the saltation. In the latter case, dune scale is determined by grain size and wind velocity

Multi Sentence Description of Complex Manipulation Action Videos

Automatic video description requires the generation of natural language statements about the actions, events, and objects in the video. An important human trait, when we describe a video, is that we are able to do this with variable levels of detail. Different from this, existing approaches for automatic video descriptions are mostly focused on single sentence generation at a fixed level of detail. Instead, here we address video description of manipulation actions where different levels of detail are required for being able to convey information about the hierarchical structure of these actions relevant also for modern approaches of robot learning. We propose one hybrid statistical and one end-to-end framework to address this problem. The hybrid method needs much less data for training, because it models statistically uncertainties within the video clips, while in the end-to-end method, which is more data-heavy, we are directly connecting the visual encoder to the language decoder without any intermediate (statistical) processing step. Both frameworks use LSTM stacks to allow for different levels of description granularity and videos can be described by simple single-sentences or complex multiple-sentence descriptions. In addition, quantitative results demonstrate that these methods produce more realistic descriptions than other competing approaches

Micromechanical finite element analyses of fire retardant woven fabric composites at elevated temperatures using unit cells at multiple length scales

This paper presents a micromechanical Finite Element (FE) model developed to predict the effective mechanical properties of glass fibre-reinforced (woven fabric) polymer composites with/without fire retardant particulate additives at elevated temperatures. The elevated mechanical properties of glass fibre-reinforced epoxy composites with/without fire retardants were predicted using three unit cells of varying length scales in micromechanical FE analysis. Theoretically predictions of flexural behaviour of these fibre-reinforced polymer composites at elevated temperatures were satisfactorily validated against experimentally measured data. The numerical model developed herein was then used for the prediction of other mechanical properties of fibre-reinforced polymer composites that would have been difficult to collect at elevated temperatures. Micromechanical FE models such as the one contained in this paper are useful to architectural engineers as they can be used to guide the design and qualification of new engineering composites that satisfy stringent Building codes in fire prone engineering applications