Slow flow across macroscopically semi-circular fibre lattices and a free-flow region of variable width—visualisation by magnetic resonance imaging

Slow flow of an incompressible Newtonian fluid across a fibrous porous medium bounded by a free-flow region of variable width was studied experimentally by magnetic resonance imaging velocimetry. The fibrous porous medium (fibre lattice) comprised of aligned rows of cylindrical rods, which were macroscopically arranged in a semi-circular fashion in a Hele-Shaw cell. The local aspects of the flow in the interior of and exterior to the fibre lattices were studied for (i) three individual semi-circular fibre lattices of different porosity and/or cylinder size, with each lattice bounded by an open channel and (ii) an assembly of five fibre lattices with the interstitial space between them forming a free-flow region. The symmetry (in a practical sense) of slow flow over symmetrical lattice-channel arrangements is demonstrated. The subtle characteristics of the flow within the lattices are seen as considerable local velocity enhancements (LVE) transverse to and in the direction of superficial flow. These LVE within the lattices strongly depend on the interface configuration of the lattice-channel arrangement, the gap size between the cylinders and the lattice porosity. The penetration depth of the LVE may even extend to the lattice centre. When a fibre lattice is a part of an assembly, the surface irregularities of neighbouring lattices create more complex tortuous flow pathways in the free-flow region. These pathways produce recurrent LVE within the fibre lattice. The implications that the above findings have for the flow, heat transfer and mass transfer in conceptually similar heterogeneous porous media used in, for example, liquid composite moulding processes and filtration processes are discussed.     

Calculation of the Thermal Conductivity and Gas Permeability in a Uniaxial Bundle of Fibers

A model of the local microstructure of a bundle of fibers is simulated and used as the basis for calculations of transport properties. This, in turn, can be used in a macroscopic model of the chemical vapor infiltration process. An expanding/overlapping circle representation of the micro-structure simulates the deposition of matrix in a uniaxial bundle of fibers. An iterative heat conduction algorithm is used to calculate the transverse thermal conductivity based on the thermal conductivities of the solid and gas phases. The permeability of gas through the microstructure is calculated for flow both parallel and transverse to overlapping cylinders using a Stokes equation and assuming a Darcy's law behavior. Both the simulations of the microstructure and associated calculations of the transport properties compare favorably with experimental data. Darcy's law for the behavior of gas in a bundle of fibers is shown to be valid for gas pressures of 5–13 kPa.     

Effect of oxidation on the chemical nature and distribution of low-temperature pyrolysis products from bituminous coal

Two bituminous coals, a high volatile Eastern Canadian and a medium volatile Western Canadian, were used to investigate the effect of oxidation on yields and chemical composition of gases, liquids and chars produced during coal pyrolysis. Pyrolysis experiments were performed at 500 °C using the Fischer assay method. Mild oxidation of coals resulted in a decrease of liquid hydrocarbon yields. Further coal oxidation increased the proportion of aromatic carbon in liquid products as determined by n.m.r., and also increased the content of oxygen in liquid products. The content of oxygen in chars was markedly lower than in corresponding coals. An attempt is made to explain reactions occurring during oxidation and subsequent pyrolysis of coal on the basis of differences in chemical composition of gases, liquids and chars.     

Multi-chord fiber-coupled interferometer with a long coherence length laser

This paper describes a 561 nm laser heterodyne interferometer that provides time-resolved measurements of line-integrated plasma electron density within the range of 10(15)-10(18) cm(-2). Such plasmas are produced by railguns on the plasma liner experiment, which aims to produce μs-, cm-, and Mbar-scale plasmas through the merging of 30 plasma jets in a spherically convergent geometry. A long coherence length, 320 mW laser allows for a strong, sub-fringe phase-shift signal without the need for closely matched probe and reference path lengths. Thus, only one reference path is required for all eight probe paths, and an individual probe chord can be altered without altering the reference or other probe path lengths. Fiber-optic decoupling of the probe chord optics on the vacuum chamber from the rest of the system allows the probe paths to be easily altered to focus on different spatial regions of the plasma. We demonstrate that sub-fringe resolution capability allows the interferometer to operate down to line-integrated densities of the order of 5 × 10(15) cm(-2).     

Landslide susceptibility mapping of Blue Nile and Tekeze River Basins using oblique rainfall-aspect rasters

This research was carried out to prepare the regional level landslide susceptibility maps by incorporating the oblique rainfall raster in the upper Blue Nile and Tekeze River basins. The oblique rainfall is the amount that actually falls on sloping surfaces, and varies considerably with slope inclination and aspect with respect to the prevailing trend of the wind direction. The monthly averaged precipitation data for the Kermit (July–September) and the Belg (March–April) rainfall seasons for the study area were acquired for the period of 1950 to 2000, and utilized to compute the oblique rainfall vectors at 40°, 45°, 50°, 55°, and 60° angles (representing “wind-driven” rainfall vectors). The weighted overlay index method using ArcGIS software was applied for this regional landslide susceptibility mapping (scales >1:100,000) by incorporating vertical rainfall intensity maps and aspect separately and as a combination (rainfall raster coupled with the slope aspect raster). The resulting landslide susceptibility maps were compared which reveals that the results obtained from using integrated rainfall/aspect raster’s (combined) were found to be more reasonable towards computing high to very high hazards than using aspect and rainfall rasters as separate layers. The susceptibility maps were validated with landslide inventory maps as well as documented rockslides, scattered throughout the study area. This reconnaissance level study could serve as guide maps in identifying those areas where more detailed landslide hazard mapping might, or should be, undertaken in the future for detailed investigations.     

Once upon a time: Crafting allegories to analyze and share the cultural complexity of strategic alignment

Allegories are fictional tales that convey meaning not explicitly set out in their narratives. In writing them, researchers move beyond the “realistic” tale to frame coherent organizational metaphors and symbols and to offer a multi-layered truth that lies “between the lines” in the often subconscious spaces of organizational life. As such, this genre offers an evocative, yet concise alternative to traditional approaches for information systems research. Drawing on a 2-year cultural study of strategic alignment of IT in two insurance organizations as illustrative context, the allegory is introduced and demonstrated in five steps to guide researchers in creating their own allegories. This illustration uses allegory to recast diverse cultural and historical data into short stories that involve magic dragons and wizards, thereby demonstrating the usefulness of the genre for comparative, multi-case designs to translate organizational features to achieve a common representation. In conclusion, the paper offers reflections on how the genre of allegory may contribute to future information systems research, to alternative styles of presentation, and to reflexive practices.     

The practitioner as researcher: Qualitative case studies in play therapy.

To help clinicians better understand case study research and encourage clinicians to share valuable experiences with others in the field, this article will define case study, identify the components of case studies, review critical considerations in case studies, and provide a recommended template for qualitative case studies. Fifteen case studies published in the International Journal of Play Therapy will be examined to review the process of these case studies, and the potential contribution of the study to illustrate the use of play therapy. Suggestions for further directions in the area of case study methodology in play therapy will be made. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stop versus yield on pedestrian-involved fatal crashes in the United States

In an effort to improve pedestrian safety, several states in the United States changed their pedestrian laws by changing the requirement that drivers yield to pedestrians in crosswalks to a requirement that drivers stop for pedestrians in crosswalks. This study examined whether this change had an effect on pedestrian safety in the United States, with its focus on low-speed roads. To examine the association between changes in pedestrian laws and changes in pedestrian-involved fatal crashes, three approaches were employed: before–after analysis, time-series analysis, and cross-sectional analysis. Pedestrian-involved fatal traffic crashes on low-speed roads were extracted from the U.S. national fatal crash database, the Fatality Analysis Reporting System (FARS), from 1980 through 2005. This study found no statistically significant reduction in pedestrian-involved fatal crashes attributable to changes in the laws, yet this finding is not definitive because of study limitations such as the omission of relevant exposure data.     

Consumption symbols as carriers of culture: A study of Japanese and Spanish brand personality constucts.

This research argues that the meaning embedded in consumption symbols, such as commercial brands, can serve to represent and institutionalize the values and beliefs of a culture. Relying on a combined emic-etic approach, the authors conducted 4 studies to examine how symbolic and expressive attributes associated with commercial brands are structured and how this structure varied across 3 cultures. Studies 1 and 2 revealed a set of "brand personality" dimensions common to both Japan and the United States (Sincerity, Excitement, Competence, and Sophistication), as well as culture-specific Japanese (Peacefulness) and American (Ruggedness) dimensions. Studies 3 and 4, which extended this set of findings to Spain, yielded brand personality dimensions common to both Spain and the United States (Sincerity, Excitement, and Sophistication), plus nonshared Spanish (Passion) and American (Competence and Ruggedness) dimensions. The meaning of the brand personality dimensions is discussed in the context of cross-cultural research on values and affect, globalization issues, and cultural frame shifting. (PsycINFO Database Record (c) 2010 APA, all rights reserved)