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91.
Slake durability study of shaly rock and its predictions 总被引:2,自引:0,他引:2
More than 35% of the earths crust is comprised of clay-bearing rocks, characterized by a wide variation in engineering properties and their resistance to short term weathering by wetting and drying phenomenon. The resistance to short-term weathering can be determined by slake durability index test. There are various methods to determine the slake durability indices of weak rock. The effect of acidity of water (slaking fluid) on slake durability index of shale in the laboratory is investigated. These methods are cumbersome and time consuming but they can provide valuable information on lithology, durability and weather ability of rock. Fuzzy set theory, Fuzzy logic and Artificial Neural Networks (ANN) techniques seem very well suited for typical complex geotechnical problems. In conjunction with statistics and conventional mathematical methods, a hybrid method can be developed that may prove a step forward in modeling geotechnical problems. During this investigation a model was developed and compared with two other models i.e., Neuro-fuzzy systems (combination of fuzzy and artificial neural network systems) and artificial neural network system, for the prediction of slake durability index of shaly rock to evaluate the performance of its prediction capability. 相似文献
92.
Sustaining the human ecological benefits of surface water requires carefully planned strategies for reducing the cumulative
risks posed by diverse human activities. The municipality of Aksaray city plays a key role in developing solutions to surface
water management and protection in the central Anatolian part of Turkey. The responsibility to provide drinking water and
sewage works, regulate the use of private land and protect public health provides the mandate and authority to take action.
The present approach discusses the main sources of contamination and the result of direct wastewater discharges into the Melendiz
and Karasu rivers, which recharge the Mamasın dam sites by the use of artificial neural network (ANN) modeling techniques.
The present study illustrates the ability to predict and/or approve the output values of previously measured water quality
parameters of the recharge and discharge areas at the Mamasin dam site by means of ANN techniques. Using the ANN model is
appreciated in such environmental research. Here, the ANN is used for estimating if the field parameters are agreeable to
the results of this model or not. The present study simulates a situation in the past by means of ANN. But in case any field
measurements of some relative parameters at the outlet point “discharge area” have been missed, it could be possible to predict
the approximate output values from the detailed periodical water quality parameters. Because of the high variance and the
inherent non-linear relationship of the water quality parameters in time series, it is difficult to produce a reliable model
with conventional modeling approaches. In this paper, the ANN modeling technique is used to establish a model for evaluating
the change in electrical conductivity (EC) and dissolved oxygen (DO) values in recharge (input) and discharge (output) areas
of the dam water under pollution risks. A general ANN modeling scheme is also recommended for the water parameters. The modeling
process includes four main stages: (1) source data analysis, (2) system priming, (3) system fine-tuning and (4) model evaluation.
Results of the ANN modeling scheme indicate that the output values are agreeable to the water quality parameters, which were
measured at the field in the static water mass of the Mamasın dam lake. Water contamination at the dam site is caused by the
continuous increase of nutrient contents and decrease of the O2 level in water causing an anaerobic condition. It may stimulate algae growth flow in such water bodies, consequently reducing
water quality. 相似文献
93.
开展干旱预测是有效应对干旱风险的前提基础,根据1960-2016年三江平原7个站点逐日降水和气温数据,利用ARIMA和ANN模型对不同时间尺度标准化降水蒸散指数(SPEI)序列进行分析建模预测。借助相关系数R、纳什效率系数NSE、Kendall秩相关系数τ、均方误差MSE和Kolmogorov-Smirnov (K-S)检验对模型的有效性进行了判定,然后分别用ARIMA和ANN模型进行12步预测,并将预测值与实际值进行比较。结果表明:(1) ARIMA模型和ANN模型对SPEI的预测能力都随时间尺度的增加而逐渐提高。(2)两种模型对3、6个月尺度SPEI的预测精度偏低,9、12、24个月的SPEI的预测精度在70%以上;(3)SPEI-9、SPEI-12、SPEI-24三个时间尺度ANN模型的预测精度优于ARIMA模型。 相似文献
94.
95.
Comparison of artificial neural network models for hydrologic predictions at multiple gauging stations in an agricultural watershed 总被引:1,自引:0,他引:1
This paper reports on an evaluation of the use of artificial neural network (ANN) models to forecast daily flows at multiple gauging stations in Eucha Watershed, an agricultural watershed located in north‐west Arkansas and north‐east Oklahoma. Two different neural network models, the multilayer perceptron (MLP) and the radial basis neural network (RBFNN), were developed and their abilities to predict stream flow at four gauging stations were compared. Different scenarios using various combinations of data sets such as rainfall and stream flow at various lags were developed and compared for their ability to make flow predictions at four gauging stations. The input vector selection for both models involved quantification of the statistical properties such as cross‐, auto‐ and partial autocorrelation of the data series that best represented the hydrologic response of the watershed. Measured data with 739 patterns of input–output vector were divided into two sets: 492 patterns for training, and the remaining 247 patterns for testing. The best performance based on the RMSE, R2 and CE was achieved by the MLP model with current and antecedent precipitation and antecedent flow as model inputs. The MLP model testing resulted in R2 values of 0·86, 0·86, 0·81, and 0·79 at the four gauging stations. Similarly, the testing R2 values for the RBFNN model were 0·60, 0·57, 0·58, and 0·56 for the four gauging stations. Both models performed satisfactorily for flow predictions at multiple gauging stations, however, the MLP model outperformed the RBFNN model. The training time was in the range 1–2 min for MLP, and 5–10 s for RBFNN on a Pentium IV processor running at 2·8 GHz with 1 MB of RAM. The difference in model training time occurred because of the clustering methods used in the RBFNN model. The RBFNN uses a fuzzy min‐max network to perform the clustering to construct the neural network which takes considerably less time than the MLP model. Results show that ANN models are useful tools for forecasting the hydrologic response at multiple points of interest in agricultural watersheds. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
96.
97.
Hydrological model comparison and assessment: criteria from catchment scales and temporal resolution
ABSTRACTThis study examines the performance of three hydrological models, namely the artificial neural network (ANN) model, the Hydrologiska Byråns Vattenbalansavdelning-D (HBV-D) model, and the Soil and Water Integrated Model (SWIM) over the upper reaches of the Huai River basin. The assessment is done by using databases of different temporal resolution and by further examining the applicability of SWIM for different catchment sizes. The results show that at monthly scale the performance of the ANN model is better than that of HBV-D and SWIM. The ANN model can be applied at any temporal scale as it establishes an artificial precipitation–runoff relationship for various time scales by only using monthly precipitation, temperature and runoff data. However, at daily scale the performance of both HBV-D and SWIM are similar or even better than the ANN model. In addition, the performance of SWIM at a small catchment size (less than 10 000 km2) is much better than at a larger catchment size. In view of climate change modelling, HBV-D and SWIM might be integrated in a dynamical atmosphere-water-cycle modelling rather than the ANN model due to their use of observed physical links instead of artificial relations within a black box.
Editor D. Koutsoyiannis; Associate editor D. Hughes 相似文献
98.
Integrating multiple images with artificial neural networks (ANN) improves classification accuracy. ANN performance is sensitive to training datasets. Complexity and errors compound when merging multiple data, pointing to needs for new techniques. Kohonen's self-organizing mapping (KSOM) neural network was adapted as an automated data selector (ADS) to replace manual training data processes. The multilayer perceptron (MLP) network was then trained using automatically extracted datasets and used for classification. Two hypotheses were tested: ADS adapted from the KSOM network provides adequate and reliable training datasets, improving MLP classification performance; and fusion of Landsat thematic mapper (TM) and SPOT images using the modified ANN approach increases accuracy. ADS adapted from the KSOM network improved training data quality and increased classification accuracy and efficiency. Fusion of compatible multiple data can improve performance if appropriate training datasets are collected. This proved to be a viable classification scheme particularly where acquiring sufficient and reliable training datasets is difficult. 相似文献
99.
人工神经网络法和线性回归法对降水相态的预报效果对比 总被引:2,自引:1,他引:1
本文主要对相同条件下线性回归法(LR)和人工神经网络法(ANN)对降雨、雨夹雪和降雪3种降水相态的预报效果进行了对比检验.选取降水发生时和发生前6h的地面2 m温度、露点温度作为预报因子,对降雨、雨夹雪和降雪进行预报.应用国家气象中心2001-2011年我国地面756站实况观测资料,其中应用2001-2010年资料对方法进行训练,2011年资料用来对比检验预报效果.结果显示,(1)两种方法对3种相态降水都有一定的预报能力,对降雪预报最好,其次是降雨和雨夹雪;(2)两种方法对北方的雨雪分界线预报比对南方的好;(3)无论是对全国还是长江中下游流域,在相同条件下,ANN法的预报效果大都优于LR法,当温度和露点温度预报准确时,ANN法对北方的雨雪分界线能进行较准确的预报. 相似文献
100.
谭峻 《测绘与空间地理信息》2014,(11)
探索科学的城市土地合理利用评价框架,从协调性、集约性和可持续利用性三个方面进行综合评价。采用2001~2010年重庆市社会经济和土地利用统计数据,运用人工神经网络模型确定土地利用的协调性、集约性和可持续性评价体系的权重,评价结果显示,2010年度重庆市土地利用比较协调、基本集约和比较可持续。因此,重庆市在土地利用方面应当注重科学引导城市空间布局,合理地确定城市人口与建设用地规模,从而完善城市基础设施体系,优化城市人居环境。 相似文献