Algorithms for GPS operation indoors and downtown

The proliferation of mobile devices and the emergence of wireless location-based services has generated consumer demand for availability of GPS in urban and indoor environments. This demand calls for enhanced GPS algorithms that accommodate high degrees of signal attenuation and multipath effects unique to the "urban channel." This paper overviews the market for location-based services and discusses algorithmic innovations that address challenges posed by urban environments. Electronic Publication     

Mobilization and transport of organic compounds from reservoir rock and caprock in geological carbon sequestration sites

Supercritical CO₂ (scCO₂) is a good solvent for organic compounds such as benzene, toluene, ethyl-benzene, and xylene (BTEX), phenols, and polycyclic aromatic hydrocarbons (PAHs). Monitoring results from geological carbon sequestration (GCS) field tests have shown that organic compounds are mobilized following CO₂ injection. Such results have raised concerns regarding the potential for groundwater contamination by toxic organic compounds mobilized during GCS. Knowledge of the mobilization mechanism of organic compounds and their transport and fate in the subsurface is essential for assessing risks associated with GCS. Extraction tests using scCO₂ and methylene chloride (CH₂Cl₂) were conducted to study the mobilization of volatile organic compounds (VOCs, including BTEX), the PAH naphthalene, and n-alkanes by scCO₂ from representative reservoir rock and caprock obtained from depleted oil reservoirs and coal from an enhanced coal-bed methane recovery site. Results showed that the extent of mobilization for the organic compounds was a function of the source rock. In fate and transport sand column experiments, moisture content was found to have an important influence on the transport of the organic compounds. In dry sand columns the majority of the compounds were retained in the column except benzene and toluene. In wet sand columns the mobility of the BTEX was much higher than that of naphthalene. Based upon the results determined for the reservoir rock, caprock, and coal samples studied here, the risk to aquifers from contamination by organic compounds appears to be relatively low; however, further work is necessary to fully evaluate the risks.     

Estimating <Emphasis Type="Italic">probable maximum loss</Emphasis> from a Cascadia tsunami

The Cascadia margin is capable of generating large magnitude seismic-tsunami. We use a 1:500 year tsunami hazard flood layer produced during a probabilistic tsunami hazard assessment as the input to a pilot study of the vulnerability of residential and commercial buildings in Seaside, OR, USA. We map building exposure, apply the Papathoma Tsunami Vulnerability Assessment Model to calculate building vulnerability and estimate probable maximum loss (PML) associated with a 1:500 year tsunami flood. Almost US$0.5 billion worth of buildings would be inundated, 95% of single story residential and 23% of commercial buildings would be destroyed with PML’s exceeding US$0.5 billion worth of buildings would be inundated, 95% of single story residential and 23% of commercial buildings would be destroyed with PML’s exceeding US116 million. These figures only represent a tiny fraction of the total values of exposed assets and loss that would be associated with a Cascadia tsunami impacting the NW Pacific coast. Not withstanding the various issues associated with our approach, this study represents the first time that PML’s have ever been calculated for a Cascadia type tsunami, and these results have serious implications for tsunami disaster risk management in the region. This method has the potential to be rolled out across the United States and elsewhere for estimating building vulnerability and loss to tsunami.     

Development and skill assessment of a real-time hydrologic-hydrodynamic-wave modeling system for Lake Champlain flood forecasting

Ocean Dynamics - In response to record-breaking flooding on Lake Champlain in 2011, the International Joint Commission launched a 5-year study to explore solutions to flooding in the binational...     

Can Hydraulic Conductivity of Fluvial Sediments be Informed by Spectral Reflectance?

Water Resources - This study explores the statistical relationship between spectral reflectance and hydraulic conductivity (K) of fluvial sediments in two Nebraska rivers. The spectral reflectance...