Regformer:基于稀疏注意力的输油管道水力压降预测方法

输油管道水力压降预测对于输油管道的生产调控十分重要,目前机器学习方法将压降预测看作回归问题,然而管道水力计算受多种因素影响,传统的机器学习方法由训练集得到的固定权重难以泛化到更多的测试样例或真实的工程场景中。本文提出一种水力压降回归预测方法Regformer,该方法将稀疏注意力机制引入回归任务,在多头注意力的基础上设计一种平滑概率方法,并融入特征投影机制。在10个公共数据集上对7种主流方法进行对比实验分析,定性实验显示Regformer对于局部的突变有很好的拟合能力;水力压降预测实验表明自注意力方法对于多变量不确定性的回归任务具有显著的优势,尤其是对极端情况的处理体现了自适应回归参数的重要性,并且Regformer用了更少的计算量取得了比Transformer更好的性能,验证了本文提出的稀疏注意力和自适应特征投影在水力压降预测任务中的优越性。

水力侵蚀预测模型GeoWEPP研究进展

总结了水力侵蚀预测模型Geo WEPP的发展历程、技术框架、适用性和局限性,从DEM数据、土地利用/覆被变化、管理因子和土壤要素等4个角度详细论述了Geo WEPP模型的研究进展,针对模型的优势及存在的问题,结合当前水文和侵蚀模型研究形势,对Geo WEPP模型未来发展的趋势与走向作了展望,指出该模型在DEM精度阈值的确定、空间尺度的转换、人类活动集中区的应用、与生态过程的结合以及WEPP与GIS集成开发5个方面有较大的拓展空间。

基于深度学习的水力发电预测

精准的水力发电预测有助于安排检修计划等。为此,文章提出一种基于门控循环单元的水力发电预测模型。首先,采用自适应噪声的完全集合经验模态分解将原始水力发电序列分解为多个序列分量;接着,运用样本熵对所有分量进行复杂度分析后对序列分量进行重构;最后,对重构后的序列分量分别构建门控循环单元进行预测,将所有预测结果进行重构获得最终的预测结果。结合实际算例分析,验证了本文所提模型的有效性。

CLIGEN随机气候生成器在天山西部中山带的适用性评价

根据中国科学院天山积雪雪崩研究站1978-2007年降水和气温的月平均资料以及在全美范围内选择参证站点得到的其他气象因子,利用CLIGEN模型分别模拟出日序列气象数据,统计出多年月平均降水量、多年月平均最高温度和多年月平均最低温度。选择模型有效系数E和平均绝对百分比误差(MAPE)为评价指标。最终确定HIBBING站点为最优参证站。HIBBING站点的模拟多年月平均降水量、月平均最高温度和月平均最低温度的模型有效系数E分别为0.980 0、0.956 3、0.996 5,平均绝对百分比误差(MAPE)分别为7.1%、10.70%、8.30%。从而确定了CLI-GEN模型在天山西部中山带的适用性。

排土场植被覆盖度及地形变化对流域水土流失的影响

煤矿区排土场的水土流失现象十分严重,盲目地进行植被重建会消耗大量资源,合理的植被覆盖度有助于指导矿区植被重建工作。基于水力侵蚀预测模型GeoWEPP,在野外调查结合遥感技术获取实测数据的基础上,以矿群为研究尺度探究了研究区排土场植被覆盖度变化对流域水土流失的影响规律并得出排土场植被覆盖度最佳范围。分析了锡林浩特矿群所在流域水土流失量增加的主要原因,在此基础上进一步模拟了地形格局变化下流域水土流失量的变化,研究了流域地形和地表植被覆盖类型变化对流域水土流失情况的影响效果;以10%的植被覆盖度为间隔、10%~90%覆盖度为区间,以50 a为模拟时长,分区域模拟分析矿群所在流域水土流失,并通过非线性均值变点法分析了生态效益最大化时的排土场植被覆盖度最佳范围。结果表明:①地形变化是研究区水土流失量增加的主要原因,地形变化对水土流失量增加的影响远高于排土场植被重建的缓解效果;②排土场边坡是发生水土流失的主要源点,仅仅进行排土场的植被重建难以较好地缓解水土流失状况,应该在地貌重塑的基础上重建排土场植被,以达到研究区生态环境优化的效益最大化;③水土流失归一化值随植被覆盖度的升高呈幂函数分布,经均值变点法计算得出锡林浩特矿群排土场的植被覆盖度最佳范围为40%~50%。

Prediction for asphalt pavement water film thickness based on artificial neural network

In order to study the variation o f the asphalt pavement water film thickness influenced by multi-factors,anew method for predicting water film thickness was developed by the combination o f the artificial neural network(ANN)a d two-dimensional shallow water equations based on hydrodynamic theory.Multi-factors included the rainfall intensity,pavement width,cross slope,longitudinal slope a d pavement roughness coefficient.The two-dimensional hydrodynamic method was validated by a natural rainfall event.Based on the design scheme o f Shen-Sha expressway engineering project,the limited training data obtained by the two-dimensional hydrodynamic simulation model was used to predict water film thickness.Furthermore,the distribution of the water film thickness influenced by multi-factors on the pavement was analyzed.The accuracy o f the ANN model was verified by the18sets o f data with a precision o f0.991.The simulation results indicate that the water film thickness increases from the median strip to the edge o f the pavement.The water film thickness variation is obviously influenced by rainfall intensity.Under the condition that the pavement width is20m and t e rainfall intensity is3m m/h,t e water film thickness is below10mm in the fast lane and20mm in t e lateral lane.Athough there is fluctuation due to the amount oftraining data,compared with the calculation on the basis o f the existing criterion and theory,t e ANN model exhibits a better performance for depicting the macroscopic distribution of the asphalt pavement water film.

System Dynamics Approach to Urban Water Demand Forecasting—A Case Study of Tianjin

A system dynamics approach to urban water demand forecasting was developed based on the analysis of urban water resources system, which was characterized by multi-feedback and nonlinear interactions among sys-tem elements. As an example, Tianjin water resources system dynamic model was set up to forecast water resources demand of the planning years. The practical verification showed that the relative error was lower than 10%. Fur-thermore, through the comparison and analysis of the simulation results under different development modes pre-sented in this paper, the forecasting results of the water resources demand of Tianjin was achieved based on sustain-able utilization strategy of water resources.

Prediction of plastic zone size around circular tunnels in non-hydrostatic stress field

This paper discusses the calculation of plastic zone properties around circular tunnels to rock-masses that satisfy the Hoek–Brown failure criterion in non-hydrostatic condition,and reviews the calculation of plastic zone and displacement,and the basis of the convergence–confinement method in hydrostatic condition.A two-dimensional numerical simulation model was developed to gain understanding of the plastic zone shape.Plastic zone radius in any angles around the tunnel is analyzed and measured,using different values of overburden(four states)and stress ratio(nine states).Plastic zone radius equations were obtained from fitting curve to data which are dependent on the values of stress ratio,angle and plastic zone radius in hydrostatic condition.Finally validation of this equation indicate that results predict the real plastic zone radius appropriately.

Simplified method for predicating consolidation settlement of soft ground improved by floating soil-cement column

A simplified method is presented for predicting consolidation settlement of soft ground improved by floating soil-cement column on the basis of double soil-layer consolidation theory. Combining the axisymmetric consolidation model and equal strain assumption, the governing equation was derived for the consolidation of clayey subsoil reinforced by soil-cement column. By modifying the boundary condition of the interface between the improved layer and underlying layer on seepage and pore-water pressure, the analytical solution of consolidation of soft ground improved by floating soil-cement column was developed under depth-dependent ramp load. The results of the parameter analysis of consolidation behavior show that the consolidation rate is closely related with the depth replacement ratio by the column and the permeability of upper layer. The influence of column-soil constrained modulus ratio and radius ratio of the influence zone to the column on consolidation is also affected by depth replacement ratio. The column-soil total stress ratio increases with time and approaches the final value accompanied with the dissipation of excess pore water pressure.

Prediction of the Nutrient Retention Capacity of the Rehabilitated Gemenc-Bdda-Karapancsa Floodplains

The GEF-WB Nutrient Reduction project aims to reduce the phosphorus inputs of the Black Sea from the Danube by means of different interventions. Hungary takes part of this project by enhancing the nutrient trapping capacity of the Gemenc and Beda-Karapancsa wetlands （GBK） which can be found on the premises of the Danube Drava National Park along the Danube River in Southern Hungary. Due to anthropogenic influences, less of small floods reach the oxbows of the area than some decades before which has a negative effect on the ecosystem. The objective of the study is to predict the nutrient reduction capacity of the Gemenc-B6da-Karapancsa water system and to make a proposal to increase this capacity. Although the floodplain vegetation has a huge nutrient intake capacity, this is limited by the fact that the floodplain is not always covered by the water of the river Danube. For that reason, a combination of hydrodynamic modelling, flood probability calculation and an estimation of suspended solids settling constitute the base of this study. The main course taken into account is the settling of suspended solids and the ratio of total nitrogen and total phosphorus to the mass of sediment is determined by local measurement results.

Combined effects of water temperature and copper ion concentration on catalase activity in Crassostrea ariakensis

A central composite experimental design and response surface method were used to investigate the combined effects of water temperature(18–34℃) and copper ion concentration(0.1–1.5 mg/L) on the catalase(CAT) activity in the digestive gland of C rassostrea ariakensis. The results showed that the linear effects of temperature were significant(P <0.01), the quadratic effects of temperature were significant( P <0.05), the linear effects of copper ion concentration were not significant(P >0.05), and the quadratic effects of copper ion concentration were significant(P <0.05). Additionally, the synergistic effects of temperature and copper ion concentration were not significant(P >0.05), and the effect of temperature was greater than that of copper ion concentration. A model equation of CAT enzyme activity in the digestive gland of C. ariakensis toward the two factors of interest was established, with R 2, Adj. R 2 and Pred. R 2 values as high as 0.943 7, 0.887 3 and 0.838 5, respectively. These findings suggested that the goodness of fit to experimental data and predictive capability of the model were satisfactory, and could be practically applied for prediction under the conditions of the study. Overall, the results suggest that the simultaneous variation of temperature and copper ion concentration alters the activity of the antioxidant enzyme CAT by modulating active oxygen species metabolism, which may be utilized as a biomarker to detect the effects of copper pollution.

In-situ stress measurements and stress change monitoring to monitor overburden caving behaviour and hydraulic fracture pre-conditioning

A coal mine in New South Wales is longwall mining 300 m wide panels at a depth of 160–180 m directly below a 16–20 m thick conglomerate strata. As part of a strategy to use hydraulic fracturing to manage potential windblast and periodic caving hazards associated with these conglomerate strata,the in-situ stresses in the conglomerate were measured using ANZI strain cells and the overcoring method of stress relief. Changes in stress associated with abutment loading and placement of hydraulic fractures were also measured using ANZI strain cells installed from the surface and from underground. Overcore stress measurements have indicated that the vertical stress is the lowest principal stress so that hydraulic fractures placed ahead of mining form horizontally and so provide effective pre-conditioning to promote caving of the conglomerate strata. Monitoring of stress changes in the overburden strata during longwall retreat was undertaken at two different locations at the mine. The monitoring indicated stress changes were evident 150 m ahead of the longwall face and abutment loading reached a maximum increase of about7.5 MPa. The stresses ahead of mining change gradually with distance to the approaching longwall and in a direction consistent with the horizontal in-situ stresses. There was no evidence in the stress change monitoring results to indicate significant cyclical forward abutment loading ahead of the face. The forward abutment load determined from the stress change monitoring is consistent with the weight of overburden strata overhanging the goaf indicated by subsidence monitoring.

The fracturing pressure prediction model for hydraulic fracturing treatment

The accurate prediction of fracturing pressure for pay zone is the very important guidance to hydraulic fracturing design and operation. The pore pressure around the wellbore happens to change variously as the fracturing fluid entering the pay zone. The change of pore pressure affects the stress-state and the fracturing pressure around the wellbore. In this paper, a new concept of the effective membrane pressure coefficient is presented according to the wall building capacity of the fracturing fluid, then the change of pore pressure around the wellbore is studied, and it is proven that the prediction model for fracturing pressure is improved.