Quantifying the recrystallization texture of tantalum

The utilization of crystallographic texture is gaining acceptance as a commercially viable tool for characterizing the attributes and confirming the quality of engineering materials. Traditionally, x-ray diffraction (XRD) involving the measurement and subsequent analysis of normal-orientation pole figures is used to determine the preferred orientation in sheet metals. Unfortunately, most XRD techniques are incapable of providing quantifying texture information of wrought tantalum. This is because integrative texture measurement methods cannot detect the presence of texture gradients and bands known to be detrimental to the performance of tantalum for select applications. Instead, discrete orientation measurement techniques such as electron backscatter diffraction are required to resolve the microtexture of tantalum. Inverse pole figure maps generated using orientation imaging microscopy have been used to gain qualitative insight into the texture character of wrought tantalum. Recently, a numerical means for quantifying the texture uniformity of tantalum (as well as other materials) from discrete orientation data has been devised and demonstrated.     

Chemical quality of depositional sediments and associated soils in New Orleans and the Louisiana peninsula following Hurricane Katrina

Hurricane Katrina made landfall on the Louisiana peninsula south of New Orleans on Aug 29, 2005. The resulting storm surge caused numerous levy breaches in the parishes of New Orleans as well as on the Louisiana peninsula. This study was conducted to determine the concentrations of inorganic and organic constituents in sediments and associated soils in New Orleans parishes and the Louisiana peninsula after the floodwaters had been removed and/or receded following Hurricane Katrina. A total of 46 sediment and soil samples were analyzed that were collected throughout New Orleans and the Louisiana peninsula. Approximately 20% of the sediment samples were analyzed, including shallow sediment samples from locations that included the top and beneath automobiles, in residential and commercial areas, and near refineries. Gasoline constituents, pesticides, and leachable heavy metals were analyzed using headspace gas chromatography/mass spectrometry (GC/MS), organic extraction GC/MS, and inductively coupled plasma/mass spectrometry, respectively. A significant number of samples had leachable As and Pb concentrations in excess of drinking water standards. The remaining metals analyzed (i.e., Cd, Cr, Cu, Hg, and V) generally had much lower leachable levels. Of the gasoline constituents, only benzene was observed above the limit of detection (of 5 microg/kg), with no samples observed as being above the method detection limits of 10 microg/kg. For the 18 pesticides analyzed, most were in the nondetectable range and all were in trace amounts that were orders of magnitude below regulatory guidelines.     

Robust and low‐communication geographic routing for wireless ad hoc networks

A novel beacon‐less algorithm called Blind Geographic Routing (BGR) is presented, which comes with an effective and robust recovery strategy to circumvent voids, and a new technique to avoid simultaneous forwarding by more than one node, features not included in other beacon‐less algorithms. BGR is the first beacon‐less algorithm that also works in 3D topologies. Additionally, BGR supports different delivery semantics, which specify how close a node must be to the destination location in order to receive the message, and how many nodes shall receive it. These semantics allow for routing not only to designated nodes with network‐wide known locations such as sinks, but to arbitrary destinations within the network area. It is shown through extensive simulation that BGR performs well even in the case of mobility, radio irregularity, and location errors, while GPSR as a beacon‐based algorithm suffers from severe problems in realistic scenarios that do not follow the unit disk graph model, even with recent enhancements of the original GPSR algorithm. Copyright © 2009 John Wiley & Sons, Ltd.