排序方式: 共有49条查询结果,搜索用时 15 毫秒
31.
Abubakar Sadiq Aliyu Ahmad Termizi Ramli Muneer Aziz Saleh 《Stochastic Environmental Research and Risk Assessment (SERRA)》2014,28(7):1897-1911
The US Environmental Protection Agency’s short-range atmospheric dispersion model (AERMOD 12345) is a good candidate for radiological dose calculations to the general public and the environment. It advanced capability should provide better confidence in the accuracy of offsite dose and risk assessment. The code has been used to compute the scaling factors for air concentration and ground level deposition of fission products based on routine and hypothetical accident releases from the NPP site in Geregu, Nigeria (7°33′N, 6°41′E). All computations were within the 16 km emergency planing zone of a generic reactor design considered by the study. The scaling factors have been used to assess the potential environmental risk of the NPP using an integrated approach to the assessment and management of environmental risks from ionizing radiation (D-ERICA). Obtained results should provide baseline information for decision making in terms of operation license provision for the pioneer NPP. 相似文献
32.
The Huntly coalfield has significant coal deposits that contain biogenically-sourced methane. The coals are subbituminous in rank and Eocene in age and have been previously characterised with relatively low to moderate measured gas (CH4) contents (2–4 m3/ton). The CO2 holding capacity is relatively high (18.0 m3/ton) compared with that of CH4 (2.6 m3/ton) and N2 (0.7 m3/ton) at the same pressure (4 MPa; all as received basis). The geothermal gradient is also quite high at 55 °C/km.A study has been conducted which simulates enhancement of methane recovery (ECBM) from these deposits using a new version of the TOUGH2 (version 2) reservoir simulator (ECBM-TOUGH2) that can handle non-isothermal, multi-phase flows of mixtures of water, CH4, CO2 and N2. The initial phase of the simulation is CH4 production for the first 5 years of the field history. The model indicates that methane production can be significantly improved (from less than 80% recovery to nearly 90%) through injection of CO2. However, although an increase in the rate of CO2 injection increases the amount of CO2 sequestered, the methane recovery (because of earlier breakthrough with increasing injection rate) decreases. Modeling of pure N2 injection produced little enhanced CH4 production. The injection of a hypothetical flue gas mixture (CO2 and N2) also produced little increase in CH4 production. This is related to the low adsorption capacity of the Huntly coal to N2 which results in almost instantaneous breakthrough into the production well. 相似文献
33.
Natural Hazards - This study systematically reviews the diverse body of research on community flood risk management in the USA to identify knowledge gaps and develop innovative and practical... 相似文献
34.
The pressure acid leach process is the most widely used method of metal extraction from laterite ores. The self-weight settling rate of the ore slurries governs the throughput of the process and is improved by adding synthetic polymers. The charge density, molecular weight, and dosage of the polymers are the key factors influencing the settling rate of the slurries. This interdisciplinary paper uses the geotechnical understanding of hindered sedimentation for a mining engineering application. A conceptual fuzzy rule-based model was developed to evaluate the initial hydraulic conductivity of polymer-modified laterite ore slurries. Identification of control parameters and selection of the model architecture (fuzzy rule-base) were based on expert judgment. The developed model was trained and validated using bench-scale settling test data. The model reasonably predicts the initial hydraulic conductivity of polymer-added laterite ore slurry with a coefficient of determination of 0.75. Rank correlation coefficient-based sensitivity analyses indicated that charge density was the most significant polymer parameter followed by molecular weight and then by dosage. Charge density accounted for more than 97% of variability in the initial hydraulic conductivity estimates for both anionic and cationic polymers. 相似文献
35.
This study focuses on the development of absolute gravity model for Pakistan based on best possible residual terrain model of gravity using residual terrain modeling technique. The datasets used for the development of model are observed gravity, global gravity models, and Shuttle Radar Topographic Mission (SRTM30) elevation data. The residual terrain modeling technique has been used in the remove-restore procedure for smoothing the observed gravity field. Different topographic elevation models were tested in the model selection and one best possible model with minimum mean and standard deviation was selected for residual terrain effects. Least square collocation technique has been used for quality control and error estimates. The best possible covariance model was established from residual gravity for onward prediction of gravity anomalies at the earth surface for error and prediction analysis. The residual terrain effect of gravity, value of free air anomaly from EGM96, and observed free air anomaly are added to normal gravity to compute the absolute gravity at earth surface. The prediction of these parameters is made by employing Lagrange interpolation with least square adjustment. The results are compared with ~5% randomly selected data points not utilized for the development of covariance function and/or model development. Spline interpolation technique has also been used for the prediction of gravity field-related parameters. Lagrange interpolation exhibits relatively superior results over spline-based interpolation. This is as per expectation due to the reason that additional gridding for spline interpolation filters the signal part as well. This fact is evident from the results of spline interpolation of Grid-I and Grid-II with relatively better prediction results in Grid-I. This version of the model is capable of prediction having limiting error of 30 mGal. The predicted results show that 96.16% of prediction data falls within above-mentioned limit with Lagrange interpolation technique with least square adjustment for whole Pakistan area. The adverse effect of gridding is absent in case of Grid-I due to relatively flat areas and predicted data matches totally with control values for both spline as well as Lagrange interpolations. However, in case of Grid-II which includes high mountains of Himalaya, gridding effect is present and the accuracy of the predicted results falls to ~92%. The computed results have been compared with absolute values predicted using EGM96 and EGM2008 models as well. The gravity field recovered with PAKGM model is much better, i.e., ~ 96.16%, than both with EGM96 and EGM2008 which is about 85% only. 相似文献
36.
Natural Resources Research - Blasting outcomes have significant impacts on downstream mining operations such as loading, hauling, crushing, milling, and mineral processing. An ideal blasting plan... 相似文献
37.
38.
39.
Solomon Tesfamariam Rehan Sadiq 《Stochastic Environmental Research and Risk Assessment (SERRA)》2008,22(1):1-15
The concepts of system load and capacity are pivotal in risk analysis. The complexity in risk analysis increases when the
input parameters are either stochastic (aleatory uncertainty) and/or missing (epistemic uncertainty). The aleatory and epistemic
uncertainties related to input parameters are handled through simulation-based parametric and non-parametric probabilistic
techniques. The complexities increase further when the empirical relationships are not strong enough to derive physical-based
models. In this paper, ordered weighted averaging (OWA) operators are proposed to estimate the system load. The risk of failure
is estimated by assuming normally distributed reliability index. The proposed methodology for risk analysis is illustrated
using an example of nine-input parameters. Sensitivity analyses identified that the risk of failure is dominated by the attitude
of a decision-maker to generate OWA weights, missing input parameters and system capacity.
相似文献
Rehan Sadiq (Corresponding author)Email: |
40.
Qian?PanEmail author Gyan?Chhipi-Shrestha Deyun?Zhou Kun?Zhang Kasun?Hewage Rehan?Sadiq 《Stochastic Environmental Research and Risk Assessment (SERRA)》2018,32(4):1099-1111
Water reuse is a viable option to increase urban water supply, especially under new realities of climate change and increasing anthropogenic activities. A sustainable water reuse application should be cost-effective and have acceptable health risk to consumers. Water reuse application evaluation is complex because data acquisitions are usually associated with the problems of uncertainty, hesitancy, and parameterization. In this paper, a generalized intuitionistic fuzzy soft set (GIFSS)-based decision support framework is proposed to provide an effective approach to describe uncertainty and hesitancy in an intuitionistic fuzzy number. In addition, the modified measures of comparison and similarity are proposed to compare water reuse applications. Then, the proposed framework is applied to the City of Penticton (British Columbia, Canada) to evaluate seven water reuse applications. The evaluation results show that the applications of garden flower watering and public parks watering are the most preferred alternatives, which are consistent with the existing practice in the city. Furthermore, the results are highly affected by the generalized parameter and the weights of evaluation criteria. Both the comparison measure-based and similarity measure-based evaluations within the same GIFSS-based framework produce consistent results, indicating an applicable and efficient methodology. 相似文献