Computational modelling of structural integrity following mass loss in polymeric charred cellular solids

A novel computational technique is presented for embedding mass-loss due to burning into the ANSYS finite element modelling code. The approaches employ a range of computational modelling methods in order to provide more complete theoretical treatment of thermoelasticity absent from the literature for over six decades. Techniques are employed to evaluate structural integrity (namely, elastic moduli, Poisson’s ratios, and compressive brittle strength) of honeycomb systems known to approximate three-dimensional cellular chars. That is, reducing the mass of diagonal ribs and both diagonal-plus-vertical ribs simultaneously show rapid decreases in the structural integrity of both conventional and re-entrant (auxetic, i.e., possessing a negative Poisson’s ratio) honeycombs. On the other hand, reducing only the vertical ribs shows initially modest reductions in such properties, followed by catastrophic failure of the material system. Calculations of thermal stress distributions indicate that in all cases the total stress is reduced in re-entrant (auxetic) cellular solids. This indicates that conventional cellular solids are expected to fail before their auxetic counterparts. Furthermore, both analytical and FE modelling predictions of the brittle crush strength of both auxetic and conventional cellular solids show a relationship with structural stiffness

Debris Slide Susceptibility Analysis in the Mount Leconte-Newfound Gap Area of the Great Smoky Mountains, Tennessee and North Carolina

In this study, Geographic Information System (GIS) techniques are combined with statistical analyses to create two debris slide susceptibility maps of the Mount Leconte-Newfound Gap area in the Great Smoky Mountains National Park (GRSMNP). This area has experienced numerous debris slide events in the past half century. Although the area has been the subject of several mass movement studies, this is the first known application of debris slide susceptibility mapping in the GRSMNP. The factors that influence the potential for slope failure are extremely variable, and the interrelationships between these factors are complex. Six topographic variables (slope angle, slope aspect, slope form (plan and profile), geology, distance to ridge crest, and precipitation) were examined to determine their influence on slope stability. Results indicate that slope angles in the 35-40 degree range are the most susceptible to failure. Among slope aspects, south facing slopes are most failure prone. Slopes that are concave in cross section are more susceptible than other slope forms. The rock type with the highest degree of susceptibility is the Anakeesta Formation. Locations that are slightly below ridge crest have the highest incidences of failure. Lastly, susceptibility tends to increase with the amount of precipitation received. The two statistical techniques used to produce the debris slide susceptibility maps were failure rate analysis and logistic regression. I found that logistic regression is a superior method because scalar values are used rather than categorical values so that a greater amount of information is retained. This type of slope failure analysis over a broad area provides important information to planners and demonstrates the utility of GIS in debris slide susceptibility mapping

The structure of Jeremiah 4:5-6:30

https://place.asburyseminary.edu/ecommonsatsdissertations/1977/thumbnail.jp

Improving Administrative Law

(Editor\u27s Note: Mr. Henderson addressed the Association on September 17. The first part of his remarks dealt with the accomplishments of the American Bar Association. The remainder of his address was concerned with the subject of administrative law and is set out here in full.

Dendroclimatological Analysis and Fire History of Longleaf Pine (\u3cem\u3ePinus Palustris\u3c/em\u3e Mill.) in the Atlantic and Gulf Coastal Plain

The purpose of this research was to use longleaf pine trees at three major sites in the Southeastern Coastal Plain to: (1) determine how longleaf pine trees respond to climate, (2) reconstruct past climate conditions using long tree-ring chronologies, (3) determine the effects of atmospheric teleconnections on longleaf pine growth, and ( 4) reconstruct fire history from fire-scar data. The native range of longleaf pine and its associated communities extends from southeastern Virginia south and westward to the Trinity River in eastern Texas. I collected samples from living and remnant longleaf pine wood in coastal South Carolina, Eglin Air Force Base in the Florida panhandle, and the Big Thicket National Preserve of Texas. In the climate response analysis, the Palmer Drought Severity Index (PDSI) and Palmer Hydrological Drought Index (PHDI) had the highest correlation with longleaf pine growth. The strongest relationships between longleaf pine growth and the Palmer indices occur between the months of July and November. Precipitation in the spring and summer was also positively related to growth at all sites. The relationship between temperature and growth was the weakest among all climate variables, but warm summer temperatures had a consistent, negative relationship with longleaf pine growth. The climate signal in the latewood was generally more robust than those in total ring width and earlywood width. developed chronologies for total ring width at all sites and for earlywood and latewood widths in Texas and South Carolina. The master chronologies for each site spanned the years from 1629-2003 in Texas, 1503-2003 in Florida, and 1455-2003 in South Carolina. I reconstructed September PHDI at all sites using a transfer function with tree-ring indices as the independent variable. For all reconstructions, the most widespread and intense year of drought since 1700 was 1925. The driest five-year period common to all reconstructions was 1951-1955. At decadal scales, extremely wet periods were often followed immediately by extremely dry periods. My reconstructions showed evidence for several historic disturbances, including the Charleston earthquake of 1886 and the arctic outbreak of 1835. Spectral analysis showed no significant spectral signatures in any of the reconstructions. Atmospheric teleconnnections such as El Nino-Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO), the North Atlantic Oscillation (NAO) and the Atlantic Multidecadal Oscillation (AMO) significantly affected longleaf pine growth at all sites, but the strength of the teleconnections varied through time. ENSO in the summer and fall correlated significantly with tree growth in Texas and South Carolina. The PDO in the year prior to growth was generally directly related to longleaf pine growth, while PDO in the current year usually showed an inverse association. The NAO from August of the previous year and May of the current year were generally negatively related to longleaf pine growth. The AMO was generally positively associated with longleaf pine growth in all months of the year. The reconstruction of fire history revealed that fire was frequent at all sites prior to the advent of fire suppression in the 20th century. The nature of the fire regime varied according to site conditions, such as the size of fire compartments and soil types. Fire frequency and seasonality of fires were also variable over time, reflecting the combined influence of climatic conditions and anthropogenic ignitions. Fire-scarred samples were not particularly abundant at any of the sites, and most scars were embedded deep inside the tree rather than on obvious, fire-scarred surfaces. Trauma rings that are abundant at the root-stem interface may be useful indicators of injury from fire, but more samples will be required to verify this hypothesis

An integrated eddy current detection and imaging system on a silicon chip

Eddy current probes have been used for many years for numerous sensing applications including crack detection in metals. However, these applications have traditionally used the eddy current effect in the form of a physically wound single or different probe pairs which of necessity must be made quite large compared to microelectronics dimensions. Also, the traditional wound probe can only take a point reading, although that point might include tens of individual cracks or crack arrays; thus, conventional eddy current probes are beset by two major problems: (1) no detailed information can be obtained about the crack or crack array; and (2) for applications such as quality assurance, a vast amount of time must be taken to scan a complete surface. Laboratory efforts have been made to fabricate linear arrays of single turn probes in a thick film format on a ceramic substrate as well as in a flexible cable format; however, such efforts inherently suffer from relatively large size requirements as well as sensitivity issues. Preliminary efforts to fully extend eddy current probing from a point or single dimensional level to a two dimensional micro-eddy current format on a silicon chip, which might overcome all of the above problems, are presented