Improved optimization methods for image registration problems

In this paper, we propose new multilevel optimization methods for minimizing continuously differentiable functions obtained by discretizing models for image registration problems. These multilevel schemes rely on a novel two-step Gauss-Newton method, in which a second step is computed within each iteration by minimizing a quadratic approximation of the objective function over a certain two-dimensional subspace. Numerical results on image registration problems show that the proposed methods can outperform the standard multilevel Gauss-Newton method

A cross-linguistic quantitative study of homophony

Homophony is ubiquitous across languages. It is an important source of ambiguity which is a distinctive feature of human language. There have been, however, few quantitative investigations on questions such as “do languages have similar degrees of homophony?”, “can the degree of homophony in a language be predictable?”. We report a preliminary attempt to answer these questions. We measure the degree of homophony of two sets of languages, one including twenty Chinese dialects and the other including three Germanic languages. It is found that there exists a strong correlation between the degree of homophony and the number of occurring syllable types (which can be taken as an estimation of the size of the phonological resource of a language), or the number of monosyllabic words in the lexicon. Furthermore, the distributional properties of homophony reflect some self-organization characteristics of language as a system, as illustrated by two pieces of evidence: the first is the correlation between the degree of homophony and the degree of disyllabification in Chinese dialects, and the second is the observation from some languages that pairs of words tend to exist in different grammatical classes, suggesting that language self-organizes in a way to decrease the chances of ambiguity. 1

Abstract Analyzing language development from a network approach

In this paper we propose some new measures of language development using network analyses, which is inspired by the recent surge of interests in network studies of many real-world systems. Children’s and care-takers ’ speech data from a longitudinal study are represented as a series of networks, word forms being taken as nodes and collocation of words as links. Measures on the properties of the networks, such as size, connectivity, hub and authority analyses, etc., allow us to make quantitative comparison so as to reveal different paths of development. For example, the asynchrony of development in network size and average degree suggests that children cannot be simply classified as early talkers or late talkers by one or two measures. Children follow different paths in a multi-dimensional space. They may develop faster in one dimension but slower in another dimension. The network approach requires little preprocessing of words and analyses on sentence structures, and the characteristics of words and their usage emerge from the network and are independent of any grammatical presumptions. We show that the change of the two articles "the " and "a " in their roles as important nodes in the network reflects the progress of children’s syntactic development: the two articles often start in children’s networks as hubs and later shift to authorities, while they are authorities constantly in the adult’s networks. The network analyses provide a new approach to study language development, and at the same time language development also presents a rich area for network theories to explore. 1

Effect of Drawing Parameters on the Properties of Polypropylene/Inorganic Particles Composites by Solid-State Die Drawing

Die drawing is an effective method for improving the properties of polymer. In this work, polypropylene (PP)/inorganic particle composites were fabricated by a solid-state die drawing process to investigate the effects of drawing parameters, such as inorganic particles types, drawing temperature, and drawing speed, on the thermal properties, microstructure, and mechanical behavior of the drawn composites. The mechanical properties of the material were significantly improved through this processing method. For the drawn PP/inorganic particle composites with 45 wt% CaCO3, when the drawing speed was 2.0 m/min and the drawing temperature was 110 °C, the density of the drawn composites reached the lowest at 1.00 g/cm3. At this time, the tensile strength, flexural strength, and impact strength of the drawn composites were 128.32 MPa, 77.12 MPa, and 170.42 KJ/m2, respectively. This work provides a new strategy for the preparation of lightweight and high-strength PP-based composites, which have broad application prospects in the field of engineering and structural materials