On formation compaction and energy balance law for liquid-saturated porous media reservoirs

In most treatments of liquid flow through porous media, it is assumed that the pore fluid and formation motions are decoupled except that porosity φ is taken to be a function of fluid pressure. This article examines the conditions under which such a decoupling is valid. More specifically, it is shown that the usual statements of the energy balance law ignore the work performed by the overburden as the formation compaction progresses. This work term is shown to be negligibly small in practical cases.     

Antibiotic resistance and genetic diversity in water-borne Enterobacteriaceae isolates from recreational and drinking water sources

A total of 240 water-borne bacteria including 72 Escherichia coli, 83 Enterobacter, 30 Klebsiella, 36 Salmonella and 19 Shigella spp. isolates from drinking and recreational water sources were assessed for antibiotic resistance and genetic diversity. Escherichia coli (88.89 %) and species of Enterobacter (86.75 %), Klebsiella (83.33 %) and Salmonella (100 %) were resistant to cefadroxil, while >94 % Shigella spp. were resistant to cefaclor and cefuroxime. Ofloxacin was the most effective antibiotic against isolates of all the genera. Multiple antibiotic resistance index identified dug well, pond and piped water supplies as high risk sources of enteric pathogens. Random amplified polymorphic DNA analysis and restriction fragment length polymorphism of amplified 16S rRNA gene were studied for genetic relatedness of Enterobacteriaceae isolates. Primer P1254 identified 10, 16, 4, 4 and 1 distinct random amplified polymorphic DNA group(s) of E. coli, Enterobacter, Klebsiella, Salmonella and Shigella species, respectively. Unlike random amplified polymorphic DNA, restriction fragment length polymorphism using AluI and HaeIII could not segregate isolates in different genetic profiles. 16S rRNA gene of three Enterobacter spp. strains from different sources with similar restriction fragment length polymorphism but different random amplified polymorphic DNA patterns was sequenced, and identified as Enterobacter hormaechei strains skg0061, 0062 and 0063. The sequence information has been submitted to GenBank (HQ322393-95). Biochemically similar but genetically diverse Enterobacteriaceae members from drinking and recreational water sources exhibited varying antibiotic sensitivity. Contamination of water sources with such multiple antibiotic-resistant enteric pathogens poses threat to human health.     

Formation compaction associated with thermal cooling in geothermal reservoirs

Concepts from the Theory of Interacting Continua are employed to develop constitutive relations for thermoelastic fluid-saturated porous media; these constitutive relations are shown to be equivalent to those of Biot in isothermal limit. For uniaxial compaction, the constitutive theory is simplified to give formation compaction as a function of changes in fluid pressure and temperature. The formation compaction due to thermal cooling is equal to 3hη[(1 + v)/3(1 − v)]ΔT.     

Role of the Water Vapour Greenhouse Effect in the Forecasting Of Fog Occurrence

Nocturnal measurements of air temperature, relative humidity, temperatureinversion-layer thickness, water vapour path and visibility-through-fog, madeunder non-foggy and foggy conditions in winter over two seasons at Delhi,are analysed to study the decrease in both rate of cooling and temperature inversion-layer thickness during the course of nights followed by fog occurrence.In particular, the decrease in the rate of cooling, compared to that on non-foggynights, is explained as due to the greenhouse warming effect by a layer of excessive,near-saturated water vapour trapped in a temperature inversion. Next, the linearprogramming technique is employed to forecast the occurrence of fog, where thevisibility-through-fog is minimized through its linear regression equation with thepair of variables, mean air temperature and temperature decrease over one hour(measuring rate of cooling at two convenient hours) in the pre-midnight period.This technique provides feasible solutions that enables one to forecast the occurrenceof radiative fog.     

Spectral reflectance pattern study of some Indian landuse/landcover features

To utilize the full potential of multispectral data acquired from aerial photographs/satellite imagery increased knowledge of the spectral reflectance characteristics of Landuse/Landcover features are required. Spectro-Radiometer was used to collect the spectral reflectance values in wavelength regions ranging from 0.48 to 0.96 u m, of some Landuse/Landcover features, in Roorkee and its surrounding areas. Spectral reflectance values, thus collected, were used to draw spectral reflectance curves of each feature separately and to determine the optimum wavelength regions for identifying each Landuse/Landcover feature. The wavelength regions, in which two dissimilar Landuse/Landcover features exhibit nearly same tonal variation in B&W aerial photographs/satellite imagery, were also determined from these curves.     

Spectral delineation of albite zone using ASTER data in Khetri Copper Belt

The Khetri Copper Belt is well known because of its economically viable Cu deposits. In this region, there is a linear narrow zone following a major crustal fracture. Along this zone, due to hydrothermal activity and subsequent alteration, a new rock, albitite has formed. The study presents an account of the spectral analysis of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) dataset for albitite mapping in the Khetri Copper Belt. Spectral angle mapper algorithm is applied on the ASTER data taking the ground sample reflectance spectra (VNIR–SWIR) and image derived spectra (TIR) as reference spectra. The albitite-classified areas are analyzed spatially and statistically to determine the extent of albitite zone in the study area. This research is to contribute to the better understanding of the spatial extent of the albitite zone which will assist in determining the potential for the mineralization in the area. The remote sensing approach of utilizing multichannel data offers the capability to resolve the key geological features of this geologically dynamic area.     

Overview of Natural Source Zone Depletion: Processes,Controlling Factors,and Composition Change

Natural source zone depletion (NSZD) has emerged as a practical alternative for restoration of light non‐aqueous phase liquid (LNAPL) sites that are in the later stages of their remediation lifecycle. Due to significant research, the NSZD conceptual model has evolved dramatically in recent years, and methanogenesis is now accepted as a dominant attenuation process (e.g., Lundegard and Johnson 2006 ; Ng et al. 2015 ). Most of the methane is generated within the pore space adjacent to LNAPL (Ng et al. 2015 ) from where it migrates through the unsaturated zone (e.g., Amos and Mayer 2006 ), where it is oxidized. While great progress has been made, there are still some important gaps in our understanding of NSZD. NSZD measurements provide little insight on which constituents are actually degrading; it is unclear which rate‐limiting factors that can be manipulated to increase NSZD rates; and how longevity of the bulk LNAPL and its key constituents can be predicted. Various threads of literature were pursued to shed light on some of the questions listed above. Several processes that may influence NSZD or its measurement were identified: temperature, inhibition from acetate buildup, protozoa predation, presence of electron acceptors, inhibition from volatile hydrocarbons, alkalinity/pH, and the availability of nutrients can all affect methanogenesis rates, while factors such as moisture content and soil type can influence its measurement. The methanogenic process appears to have a sequenced utilization of the constituents or chemical classes present in the LNAPL due to varying thermodynamic feasibility, biodegradability, and effects of inhibition, but the bulk NSZD rate appears to remain quasi‐zero order. A simplified version of the reactive transport model presented by Ng et al. 2015 has the potential to be a useful tool for predicting the longevity of key LNAPL constituents or chemical fractions, and of bulk LNAPL, but more work is needed to obtain key input parameters such as chemical classes and their biodegradation rates and any potential inhibitions.     

Holocene humidity fluctuations in Sweden inferred from dendrochronology and peat stratigraphy

Tree-ring and peat stratigraphy data were examined back to 5000 BC in order to identify and compare humidity changes in Fennoscandia. The temporal variation in distribution of Scots pine ( Pinus sylvestris L.) was used as a measure of past lake-level fluctuations in central Sweden. The chronology, which spans 2893 BC–AD 1998 with minor gaps in AD 887–907 and 1633–1650 BC and with additional floating chronologies back to 4868 BC, was cross-dated and fixed to an absolute timescale using a chronology from Torneträsk, northern Sweden. The peat stratigraphy from the Stömyren peat bog, south-central Sweden, was transformed into humification indices to evaluate humidity changes during the past 8000 years. The peat chronology is established by four tephra datings and eight ¹⁴C datings. Synchronous periods of drier conditions, interpreted from regeneration and the mortality pattern of pine, tree-ring chronology and peat humification, were recognized at c. 4900–4800 BC, 2400–2200 BC, 2100–1800 BC, 1500–1100 BC, AD 50–200, AD 400–600 and AD 1350–1500. Possible wetter periods were encountered at 3600–3400 BC, 3200–2900 BC, 2200–2100 BC, 1700–1500 BC, 1100–900 BC, 100 BC-AD 50, AD 200–400, AD 750–900 and AD 1550–1700. The wet and dry periods revealed by the tree rings and peat stratigraphy data indicate considerable humidity changes in the Holocene.     

Fatigue life of critical members in a railway truss bridge

The fatigue life of critical members, such as hangers, floor-beams and stringers in a single track, open deck railroad truss bridge, was investigated for various unit freight trains, operating at different speeds. A partial bridge model was used, along with a three-car train, to determine the stress cycles. For determining the fatigue lives of critical members, four fully-loaded trains per day were assumed to pass over the bridge. Each train was assumed to consist of one hundred 70-ton cars or seventy 100-ton cars. The 100-ton freight cars cause large stress ranges, and consequently shorter fatigue lives than the 70-ton freight cars. For the hundred-car train, with 70-ton and 100-ton cars mixed in various proportions, the fatigue lives became shorter as the percentage of 100-ton cars in the consist was increased. The impact percentages were also studied.     

Sedimentation of particulate matter in the Dona Paula Bay, West Coast of India during November to May 1995–1997

Data on hydrography, nutrients, suspended particles, and sedimented particles were collected at weekly intervals from November to May during 1995 to 1997 at a station in the coastal waters of Dona Paula Bay, India. Suspended and sedimented particles were analyzed for total suspended matter (SPM), total sedimented particulate matter (TPM), particulate organic carbon (POC), particulate organic nitrogen (PON), chlorophylla (chla), and diatom abundance. Variations in hydrography and nutrients influenced the quantity and composition of sedimented particles. The TPM, POC, PON, and chla fluxes showed small-scale seasonal variations and were higher in the summer (February to May) than in the winter (November to January). Resuspension of carbon accounted for approximately 25% of the gross POC and was highest in April 1997 (45%). The mean net POC flux was 197±90 mg C m⁻² d⁻¹ and accounts for 4.6% of the TPM. The average C∶N (w∶w) ratio of the sedimented material was 13.2±6.6. The POC:chla ratio was relatively higher in the sedimented material as compared to the suspended material. The particulate carbon reaching the bottom sediment was 39% of the primary production. The low organic carbon concentration (approximately 0.1% of dry sediment) in the sediments implies that about 98% of the sedimented carbon was either consumed at the sedimentwater interface or resuspended/advected before it was finally buried into the sediments.