Integrity Monitoring of Pressurized Gas Cylinders Using the SSUE Technique

Spread-Spectrum Ultrasonic Evaluation (SSUE) is a newly emerging technique for the global inspection and integrity monitoring of objects such as pressurized gas cylinders and structures such as bridges and airframes. This technique is based upon the measurement of an ultrasonic correlation signature which is sensitive to the structural and material properties of the test object. Recently, we applied the technique to pressurized gas cylinders and found that it was very sensitive to small changes in the cylinder. Specifically, we looked at the ability of the SSUE method to detect artificially-induced cracks at various points on the outside of the cylinder

Design and Fabrication of an Industrial-Grade Instrument to Measure Texture and Predict Drawability in Sheet Metal

Texture in sheet metal must be controlled in the rolling process to assure the fabrication properties desired in later manufacturing. Drawability is one of the required engineering properties in a family of applications including beverage cans, propane tanks, and automotive parts

Approximate and dynamic rank aggregation

Rank aggregation, originally an important issue in social choice theory, has become more and more important in information retrieval applications over the Internet, such as meta-search, recommendation system, etc. In this work, we consider an aggregation function using a weighted version of the normalized Kendall-τ distance. We propose a polynomial time approximation scheme, as well as a practical heuristic algorithm with the approximation ratio two for the NP-hard problem. In addition, we discuss issues and models for the dynamic rank aggregation problem. © 2004 Elsevier B.V. All rights reserved.link_to_subscribed_fulltext9th International Computing and Combinatorics Conference, Big Sky, MT, 25-28 July 2003. In Theoretical Computer Science, 2004, v. 325 n. 3, p. 409-42

Hong Kong: How sustainability is managed in a high density city

organized by France (Pacific Territories) National Committee for Pacific Economic Cooperatio

The effects of annual harvesting on the subsequent phytomass and species composition of grassland and fernland: A Hong Kong case

Anthropogenic grasslands mixed with fern and shrubland, on scales from metres to kilometres, are widespread in tropical Southeast Asia, and especially in southern China and adjoining regions where harvesting for domestic fuel is a major factor in their maintenance. Baseline surveys in grassland and fernland in 1989-90 and resurveys in 2001 of three 6 × 20 m plots in Wong Chuk Yuen, Hong Kong, showed substantial change in species composition and total aboveground phytomass as a result of annual harvesting, with more pronounced change in the fernland. Under harvesting pressure, the species composition of the grassland changed considerably, though the proportions of the various life-forms did not. Ischaemum spp. and Miscanthus floridulus increased whereas Themeda gigantea died out while the proportion of other grass species remained much the same. Under the same regime the species composition and life-forms of the fernland changed markedly. The proportion of Dicranopteris fern dropped substantially, though still comprising a third of the phytomass by 2001. The shrub Melastoma survived harvesting. A firebreak cut in the fernland became grassy under annual harvesting and remained grassy six years after cutting ceased. The annual harvests from the growth-years 1991-2000 showed a substantial though variable increase in total phytomass. Analyses relating harvested phytomass with various climatic parameters showed no significant correlations. Some possible reasons for this are suggested. Although annual harvesting was clearly sustainable over the ten years of observation, the question of continued sustainability on sites harvested for centuries, the situation in much of southern China and parts of upland mainland Southeast Asia, remains unresolved. © 2004 Department of Geography, National University of Singapore and Blackwell Publishers Ltd.link_to_subscribed_fulltex

Finding Linear Motif Pair from Protein Interaction Networks: A Probabilistic Approach

To exploit theoretical advances in elastic wave inverse scattering, an automated multiviewing ultrasonic transducer system and the associated signal processing algorithms have been developed at the Ames Laboratory for the reconstruction of the size, shape, and orientation of volumetric flaws [1]. The flaw sizing algorithm is based on elastic wave inverse scattering theories in the long and intermediate wavelength, regime [2,3] and the three-dimensional reconstruction algorithm finds the equivalent ellipsoid that best fits the flaw sizes in the various viewing directions [4,5]. The original multiprobe system consists of six peripheral transducers equally spaced in a circle surrounding one transducer at the center. The peripheral transducers may be tilted at an angle toward the center to increase the aperture and can also be translated along their respective axes to allow an equilization of the acoustic propagation time. The axis of the aperture cone is normally placed perpendicular to the part surface. The flaw sizing procedure was a one-dimensional inverse Born algorithm to determine the flaw’s centroid-to-tangent plane distances for a number (normally 13 or 19) of pulse-echo or pitch-catch scattering directions within a finite aperture cone. The flaw sizes are then used as inputs to a nonlinear least squares regression program to yield a complete geometric reconstruction in the form of three semi-axes and three Euler angles of the best-fit ellipsoid. Using this system, successful reconstructions have been obtained for both oblate spheroidal (disk-like) and prolate spheroidal (rod-like) inclusions and voids. The readers are referred to a complete description of the system in Ref. 1

Chinese Merchants in the Hong Kong Colonial Context, 1840s-1900s

The texture (preferred grain orientation) of rolled metal plates influences a number of important properties. Included are their form-ability into complex shapes such as beverage cans, vehicle bodies, or airframe skins, and their response to static or dynamic loading when the resulting components are placed into service [1–3]. Considerable benefit would be gained from the development of instrumentation which could measure texture in real time for process control applications or which could easily establish the texture of incoming materials or finished components so that their elastic or plastic mechanical properties could be estimated. As an example of the economic benefits of such a device, it has been estimated that $40 million could be saved by the aluminum can industry through adequate texture monitoring [4]

A multivariate twin study of hippocampal volume, self-esteem and well-being in middle-aged men.

Self-esteem and well-being are important for successful aging, and some evidence suggests that self-esteem and well-being are associated with hippocampal volume, cognition and stress responsivity. Whereas most of this evidence is based on studies on older adults, we investigated self-esteem, well-being and hippocampal volume in 474 male middle-aged twins. Self-esteem was significantly positively correlated with hippocampal volume (0.09, P = 0.03 for left hippocampus, 0.10, P = 0.04 for right). Correlations for well-being were not significant (Ps > 0.05). There were strong phenotypic correlations between self-esteem and well-being (0.72, P < 0.001) and between left and right hippocampal volume (0.72, P < 0.001). In multivariate genetic analyses, a two-factor additive genetic and unique environmental (AE) model with well-being and self-esteem on one factor and left and right hippocampal volumes on the other factor fits the data better than Cholesky, independent pathway or common pathway models. The correlation between the two genetic factors was 0.12 (P = 0.03); the correlation between the environmental factors was 0.09 (P > 0.05). Our results indicate that largely different genetic and environmental factors underlie self-esteem and well-being on one hand and hippocampal volume on the other