Convergence of iterative coupling for coupled flow and geomechanics

In this paper, we study solving iteratively the coupling of flow and mechanics. We demonstrate the stability and convergence of two widely used schemes: the undrained split method and the fixed stress split method. To our knowledge, this is the first time that such results have been rigorously obtained and published in the scientific literature. In addition, we propose a new stress split method, with faster convergence rate than known schemes. These results are specially important today due to the interest in hydraulic fracturing (Dean and Schmidt SPE J. 14:707–714, 2009; Ji et al. SPE J. 14:423–430, 2009; Samier and De Gennaro 2007; Settari and Maurits SPE J. 3:219–226, 1998), in oil and gas shale reservoirs.     

Computational engineering and science methodologies for modeling and simulation of subsurface applications

We discuss computational engineering and science (CES) methodologies and tools applicable to a variety of subsurface models and their couplings. First we overview both basic and widely recognized multiphase and multicomponent models. In the CES methodologies area we focus on accurate and robust numerical algorithms and linear and nonlinear solvers with parallel scalability. In the CES tools area, we discuss a few representative programming tools and technologies. We present several simulation examples which reflect the experiences of the research group at the Center for Subsurface Modeling at The University of Texas at Austin.     

Can saltwater toxicity be predicted from freshwater data?

The regulation of substances discharged to estuarine and coastal environments relies upon data derived from ecotoxicity tests. Most such data are generated for freshwater rather than saltwater species. If freshwater toxicity data are related to saltwater toxic effects in a systematic and predictable way, the former can be used to predict the latter. This would have economic advantages due to a reduction in toxicity testing of saltwater species. If toxicity data are plotted as species sensitivity distributions, four theoretical relationships between freshwater and saltwater can be envisaged. Examples show that each one of these relationships is supported by empirical data. These examples show that although there is considerable potential for freshwater to saltwater prediction, species parity and representativeness need to be examined for each chemical substance to avoid bias.     

How multiagency partnerships can successfully address large-scale pollution problems: a Hawaii case study

Oceanic circulation patterns deposit significant amounts of marine pollution, including derelict fishing gear from North Pacific Ocean fisheries, in the Hawaiian Archipelago [Mar. Pollut. Bull. 42(12) (2001) 1301]. Management responsibility for these islands and their associated natural resources is shared by several government authorities. Non-governmental organizations (NGOs) and private industry also have interests in the archipelago. Since the marine debris problem in this region is too large for any single agency to manage, a multiagency marine debris working group (group) was established in 1998 to improve marine debris mitigation in Hawaii. To date, 16 federal, state, and local agencies, working with industry and NGOs, have removed 195 tons of derelict fishing gear from the Northwestern Hawaiian Islands. This review details the evolution of the partnership, notes its challenges and rewards, and advocates its continued use as an effective resource management tool.     

SPICES: spectro-polarimetric imaging and characterization of exoplanetary systems

SPICES (Spectro-Polarimetric Imaging and Characterization of Exoplanetary Systems) is a five-year M-class mission proposed to ESA Cosmic Vision. Its purpose is to image and characterize long-period extrasolar planets and circumstellar disks in the visible (450?C900 nm) at a spectral resolution of about 40 using both spectroscopy and polarimetry. By 2020/2022, present and near-term instruments will have found several tens of planets that SPICES will be able to observe and study in detail. Equipped with a 1.5 m telescope, SPICES can preferentially access exoplanets located at several AUs (0.5?C10?AU) from nearby stars (<25 pc) with masses ranging from a few Jupiter masses to Super Earths (??2 Earth radii, ??10 M_??) as well as circumstellar disks as faint as a few times the zodiacal light in the Solar System.     

High resolution investigation of the 7 μm region of the ethane spectrum

Building upon previous studies, we re-investigated the ethane spectrum between 1330 and 1610 cm^?1 by combining unapodized spectra obtained at room temperature with a Bruker Fourier transform spectrometer (FTS) in Brussels and at 131 K with a Bruker FTS in Pasadena. The maximum optical path differences (MOPD) of the two datasets were 450 and 323.7 cm, corresponding to spectral resolutions of 0.0020 and 0.0028 cm^?1, respectively. Of the 15,000 lines observed, over 4592 transitions were assigned to the ν₆ (at 1379 cm^?1), ν₈ (at 1472 cm^?1), ν₄+ν₁₂ (at 1481 cm^?1) and 2ν₄+ν₉ (at 1388 cm^?1) bands, and another 1044 transitions were located for the ν₄+ν₈?ν₄ hot band (at 1472 cm^?1). Our new analysis included an improved implementation of the Hamiltonian calculation needed to interpret the complex spectral structures caused by numerous interactions affecting these four modes of vibration. From these results, we created the first line-by-line database containing the molecular parameters for over 20,000 ¹²C₂H₆ transitions at 7 μm.     

Earth observations during space shuttle mission STS‐45 mission to planet earth March 24—April 2, 1992

Abstract

The impact of animals upon the landscape, through such actions as trampling, feeding, burrowing, mounding, and dam building, is a topic of interest in university geography classrooms. However, the relatively fine‐scale nature of most such impacts precludes its examination via remote sensing. Nevertheless, remote sensing of many types of animal impact is possible, and in this paper I illustrate several such examples, primarily drawn from free‐access sites on the World Wide Web, using a variety of remote sensing platforms. Instructors of physical geography or resource/land use management courses can thus introduce a variety of remote sensing concepts and imagery types in their classrooms while at the same time examining the role of animals on the landscape.     

Southern urbanism or a world of cities? Modes of enacting a more global urban geography in textbooks,teaching and research

Despite growing attentiveness to cities in the global south, questions remain as to how to enact a more global urban studies. We analyze five contemporary textbooks as a lens into how southern cities ought to be incorporated in teaching as well as the field of urban geography. We find both separate chapters for southern cities (southern urbanism), and southern cities integrated into existing thematic chapters (a world of cities). We further show that i) the global south is 2–33% of the content; ii) information about the south is typically more general than the north, but never as universal trends iii) representations differ not just in content but in style and iv) the south is exemplar or exception rather than as a source of theory. We suggest that geographers must continue their efforts in thinking about how southern cities should be incorporated in urban geography in and outside the classroom.     

A Review of “Appalachian Aspirations: The Geography of Urbanization and Development in the Upper Tennessee River Valley, 1865–1900”

This article tests the explanatory power and interactions among five alternative explanations of environmental knowledge: (1) local information availability, (2) neighborhood characteristics, (3) environmental attitudes, (4) personal empowerment, and (5) information seeking. Using random forest and conditional inference trees, the article analyzes survey responses and finds that attitudes about personal empowerment and frequent information seeking are the strongest predictors of knowledge. The study offers random forest and conditional inference trees as statistical tools for complex data sets and studies that test hypotheses generated from multiple theories. We discuss the influence of knowledge differences over inclusive sustainability discussions.     

Tracing offshore low-salinity plumes in the Northeastern Gulf of Mexico during the summer season by use of multispectral remote-sensing data

To trace offshore surface low-salinity water (LSW) in the northeastern Gulf of Mexico, a proxy was developed using the surface water beam attenuation coefficient (c _p), and salinity matched with synchronous Sea-viewing Wide Field-of-view Sensor (SeaWiFS) satellite data from three annual summer cruises (July 1998–August 2000) using a two-step empirical approach. First, a relationship between in-situ salinity and c _p was obtained. Second, in-situ c _p was matched with SeaWiFS radiance ratios of all available blue-to-green wavelengths. Finally, satellite-derived surface salinity was determined directly by combining the two empirical relationships, providing a robust estimate over a range of salinities (26–36). This significantly improves the limited spatial and temporal resolution of surface salinity distribution obtained by shipboard sampling. The resulting correlation is best explained as mixing between low-salinity plume waters and normal salinity Gulf waters. The empirical relationships were used to map satellite-derived salinity using the average of SeaWiFS images during each summer cruise. As expected for summer, spatial patterns of LSW plumes with high c _p, particulate matter (PM), particulate organic carbon (POC), and chlorophyll-a (Chl-a) were connected to the mouth of the Mississippi River Delta and extended to the east-southeast. Normal salinity Gulf water with lower c _p, PM, POC, and Chl-a was confined to the shelf and upper slope in the eastern part of the study area, outside the plumes. This proxy approach can be applied throughout the region of shipboard sampling for more detailed coverage and analysis.