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941.
Pushpa Tuppad Narayanan Kannan Raghavan Srinivasan Colleen G. Rossi Jeffrey G. Arnold 《Water Resources Management》2010,24(12):3115-3144
The Bosque River Watershed in Texas is facing a suite of water quality issues including excess sediment, nutrient, and bacteria.
The sources of the pollutants are improperly managed cropland and grazing land, dairy manure application, and effluent discharge
from wastewater treatment facilities. Several best management practices (BMPs) have been proposed for pollution reduction
and watershed protection. The overall objectives of this study were to demonstrate a modeling approach using Soil and Water
Assessment Tool (SWAT) model to simulate various BMPs and assess their long-term impacts on sediment and nutrient loads at
different spatial levels. The SWAT model was calibrated and validated for long-term annual and monthly flows at Valley Mills
and for monthly sediment, total nitrogen (TN) and total phosphorus (TP) at Hico and Valley Mills monitoring locations. The
BMPs including streambank stabilization, gully plugs, recharge structures, conservation tillage, terraces, contour farming,
manure incorporation, filter strips, and PL-566 reservoirs were simulated in the watershed areas that met the respective practice’s
specific criteria for implementation. These BMPs were represented in the pre- and post-conditions by modifying one or more
channel parameters (channel cover, erodibility, Manning’s n), curve number (CN), support practice factor (P-factor), filter
strip width, and tillage parameters (mixing efficiency, mixing depth). The BMPs were simulated individually and the resulting
Hydrologic Response Units (HRUs), subwatershed, and watershed level impacts were quantified for each BMP. Sensitivity of model
output values to input parameters used to represent the BMPs was also evaluated. Implementing individual BMPs reduced sediment
loads from 3% to 37% and TN loads from 1% to 24% at the watershed outlet; however, the changes in TP loads ranged from 3%
increase to 30% decrease. Higher reductions were simulated at the subwatershed and HRU levels. Among the parameters analyzed
for sensitivity, P-factor and CN were most sensitive followed by Manning’s n. The TN and TP outputs were not sensitive to
channel cover. This study showed that the SWAT modeling approach could be used to simulate and assess the effectiveness of
agricultural best management practices. 相似文献
942.
This paper provides a new test technique for detecting defects in Through Silicon Via (TSV) in 3-D ICs and presents a substrate-dependent
equivalent electrical model for TSVs. Process-related defects that affect the functional electrical performance of the TSV
are identified, and fault models are developed for each individual defect. The fault models are integrated into the equivalent
electrical model of the TSV for testing. Our test technique uses an RF carrier signal modulated with a multi-tone signal with
added Gaussian white noise to synthesize the test stimulus; the peak-to-average ratio is measured as output response. We find
a significant difference in peak-to-average ratio between defect-free and defective TSVs. Our test technique is very sensitive
to small defects in these nanostructures, thereby identifying the defects with high accuracy. 相似文献
943.
R. Narayanasamy M. Ravi chandran C. Sathiya Narayanan N. L. Parthasarathi R. Ravindran 《International Journal of Mechanics and Materials in Design》2006,3(4):293-307
In this paper, the influence of annealing temperature on formability, fracture behavior, void nucleation, its growth, and
coalescence are studied. The voids and fracture behavior are studied as a function of various void parameters, namely δd-factor
(ligament thickness between consecutive voids), d factor (ratio of δd and radius of the void), void area fraction (Va) and L/W ratio (ratio of length to width of the void). The L/W ratio of the oblate or prolate voids at fracture is correlated
with the mechanical properties, microstructure, minor strain at fracture (ε2), Mohr’s circle shear strains, stress, and strain triaxiality factors. The Lode factor (θ) is determined and correlated with
the Stress triaxiality factor (T), which is the ratio of mean stress (σm) to effective stress (σe). In addition, the Void area fraction (Va), which is the ratio of void area to the representative sample area, is determined correlated with the Strain triaxiality
factor (To). It is found that the sheets annealed at 300°C, possesses better formability due to lower d-factor, higher
and -values, greater void area fraction and lower L/W ratio of void accommodating more plastic deformation. 相似文献
944.
R. Narayanasamy V. Senthilkumar K. S. Pandey 《International Journal of Mechanics and Materials in Design》2006,3(2):175-184
An experimental research work was performed for the understanding of the workability behavior of pure iron preforms produced
through powder metallurgy route during hot forging under triaxial stress state condition. Relationship was established between
the formability stress index and the axial strain. A relationship between the relative density and the axial strain was also
established. Various stress ratio parameter under triaxial stress state condition which indicates the workability behavior
of the material namely, , and were studied. An attempt has also been made to relate the stress ratio parameters with the relative density (R). 相似文献
945.
Concentrations of four perfluorinated contaminants, including perfluorooctanesulfonate (PFOS) and perfluorooctanoic acid (PFOA), were measured in liver tissue from 80 adult female sea otters collected from the California coast during 1992-2002. Concentrations of PFOS and PFOA were in the ranges of <1-884 and <5-147 ng/g, wet wt, respectively. Concentrations of PFOA in the livers of these sea otters were among the highest values reported for marine mammals to date. Liver tissue from 6 male sea otters also was analyzed and contained significantly higher concentrations of PFOS than did tissues from female otters. To examine the association between exposures and potential effects, concentrations of PFOS and PFOA were compared among the adult female otters that died from infectious diseases, noninfectious causes, and from apparent emaciation. Concentrations of both PFOA and PFOS were significantly higher in sea otters in the infectious disease category than in the noninfectious category. Concentrations of PFOS and PFOA were not significantly different between noninfectious and emaciated otters, suggesting that the poor nutritive (body) status of emaciated otters did not affectthe concentrations of perfluorochemicals in livers. Concentrations of PFOA increased significantly from 1992 to 2002, whereas PFOS concentrations increased from 1992to 1998 and then decreased after 2000. Significant association between infectious diseases and elevated concentrations of PFOS/PFOA in the livers of sea otters is a cause for concern and suggests the need for further studies. 相似文献
946.
The dispersibility in deionized water of hydroxyapatite (HA) synthesized by a high-temperature (1000°C) solid-state reaction between tricalcium phosphate and calcium hydroxide was investigated as a function of the pH of the medium and the quantity of two dispersing agents (A = inorganic, B = organic) added to the slips. Although pH modification had a negligible effect on dispersibility, both of the dispersing agents produced a good dispersion at considerably higher concentrations (>2 wt% of HA). At optimum amounts (2–4 wt%) of the dispersing agents, the slips showed near-Newtonian flow behavior up to 45 wt% solids loading and non-Newtonian behavior at >50 wt%. By the optimal addition of dispersing agents and conditioning by ball milling, 60–67 wt% (32–39 vol%) solids-loaded HA slips could be cast into plaster molds to produce 50%–58% dense green bodies, which, in turn, sintered to 90%–94% density in the temperature range 1300°–1400°C. The sintered HA exhibited a three-point flexural strength of 40–60 MPa and a homogeneous microstructure, with interspersed microporosities. 相似文献
947.
Wastewater treatment plants have recently been identified as a significant pathway for the introduction of perfluoroalkyl surfactants (PASs) to natural waters. In this study, we measured concentrations and fate of several PASs in six wastewater treatment plants (WWTPs) in New York State. We also monitored and measured matrix effects (ionization suppression and enhancement) by postcolumn infusion and standard additions. Concentrations of perfluorooctanoate (PFOA) in effluents of the six WWTPs ranged from 58 to 1050 ng/L. Perfluorooctanesulfonate (PFOS) was also ubiquitous in effluents of these WWTPs, albeit at much lower concentrations (3-68 ng/L). Two of these WWTPs employed identical treatment processes, with similar hydraulic retentions, but differed only in that Plant B treated domestic and commercial waste, whereas Plant A had an additional industrial influence. We found that this industrial influence resulted in significantly greater mass flows of all of the PASs analyzed. Primary treatment was found to have no effect on the mass flows of PASs. Secondary treatment by activated sludge in Plant A significantly increased (p < 0.05) the mass flows of PFOS, PFOA, perfluorononanoate (PFNA), perfluorodecanoate (PFDA), and perfluoroundecanoate (PFUnDA). However, in Plant B, only the mass flow of PFOA was significantly increased. The observed increase in mass flow of several PASs may have resulted from biodegradation of precursor compounds such as fluorotelomer alcohols, which is supported by significant correlations in the mass flow of PFOA/PFNA and PFDA/PFUnDA. Furthermore, the masses of PFDA and PFUnDA were significantly correlated only after the secondary treatment. In Plant A, concentrations of odd-number PFCAs were greater than those of even-number PFCAs, and concentration decreased with increasing chain length (from C8 to C12). A different pattern was observed in sludge samples, in which the dominance of PFOA decreased, and PFDA and PFUnDA increased, suggesting preferential partitioning of longer-chain PFCAs to sludge. 相似文献
948.
I. Kruusenberg L. Matisen Q. Shah A.M. Kannan K. Tammeveski 《International Journal of Hydrogen Energy》2012
Hydrogen–oxygen fuel cells using an alkaline anion exchange membrane were prepared and evaluated. Various non-platinum catalyst materials were investigated by fabricating membrane-electrode assemblies (MEAs) using Tokuyama membrane (# A201) and compared with commercial noble metal catalysts. Co and Fe phthalocyanine catalyst materials were synthesized using multi-walled carbon nanotubes (MWCNTs) as support materials. X-ray photoelectron spectroscopic study was conducted in order to examine the surface composition. The electroreduction of oxygen has been investigated on Fe phthalocyanine/MWCNT, Co phthalocyanine/MWCNT and commercial Pt/C catalysts. The oxygen reduction reaction kinetics on these catalyst materials were evaluated using rotating disk electrodes in 0.1 M KOH solution and the current density values were consistently higher for Co phthalocyanine based electrodes compared to Fe phthalocyanine. The fuel cell performance of the MEAs with Co and Fe phthalocyanines and Tanaka Kikinzoku Kogyo Pt/C cathode catalysts were 100, 60 and 120 mW cm−2 using H2 and O2 gases. 相似文献
949.
Hema L. Degala Jasmine R. Scott Francisco I. Rico Espinoza Ajit K. Mahapatra Govind Kannan 《Journal of Food Safety》2020,40(1):e12740
Ozonated and electrolyzed water have been reported to have bactericidal activities against most pathogenic and spoilage microorganisms associated with fresh meat and contact surfaces in meat processing facilities at room temperature. However, antimicrobial effects of these two treatments combined are not known. Therefore, the objective of this study was to evaluate the effectiveness of ozonated and electrolyzed water in combination for inactivating Escherichia coli K12 on goat meat. The combination of ozonated water and alkaline electrolyzed water resulted in higher log reductions (1.03 CFU/ml) compared to ozonated water alone (0.53 CFU/ml). Regression analysis performed using the GInaFiT tool showed that nonlinear Weibull models were more effective than log-linear models for describing the inactivation kinetics of E. coli K12 on goat meat. 相似文献
950.