Forecasting water deficit is challenging because it is modulated by uncertain climate, different environmental and anthropic factors, especially in arid and semi-arid northwestern China. The monthly water deficit inde...
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Forecasting water deficit is challenging because it is modulated by uncertain climate, different environmental and anthropic factors, especially in arid and semi-arid northwestern China. The monthly water deficit index D at 44 sites in northwestern China over 1961-2020 were calculated. The key large-scale circulation indices related to D were screened using Pearson's correlation (r). Subsequently, we predicted monthly D with the multi-variable linear regression (MLR) and random forest (RF) models at certain lagged times after being strictly calibrated and validated. The results showed the following: (1) The r between the monthly D and the screened key circulation indices varied from 0.71 to 0.85 and the lagged time ranged from 1 to 12 months. (2) The calibrated and validated performance of the established MLR and RF models were all good at the 44 sites. Overall, the RF model outperformed the MLR model with a higher coefficient of determination (R-2 > 0.8 at 38 sites) and mean absolute percentage error (MAPE < 50% at 30 sites). (3) The Pacific Polar Vortex Intensity (PPVI) had the greatest impact on D in northwestern China, followed by SSRP, WPWPA, NANRP, and PPVA. (4) The forecasted monthly D values based on RF models indicated that the water deficit in northwestern China would be most severe (-239.7 to -62.3 mm) in August 2022. In conclusion, using multiple large-scale climate signals to drive a machine learning model is a promising method for predicting water deficit conditions in northwestern China.
Fracture porosity is one of the most effective parameters for reservoir productivity and recovery efficiency. This study aims to predict and improve the accuracy of fracture porosity estimation through the application...
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Fracture porosity is one of the most effective parameters for reservoir productivity and recovery efficiency. This study aims to predict and improve the accuracy of fracture porosity estimation through the application of advanced machine learning (ML) algorithms. A novel approach was introduced for the first time to estimate fracture porosity by reaping the benefits of petrophysical and fullbore formation micro-imager (FMI) data based on employing various stand-alone, ensemble, optimisation and multi-variable linear regression (MVLR) algorithms. This study proposes a ground-breaking two-step committee machine (CM) model. Petrophysical data containing compressional sonic-log travel time, deep resistivity, neutron porosity and bulk density (inputs), along with FMI-derived fracture porosity values (outputs), were employed. Nine stand-alone ML algorithms, including back-propagation neural network, Takagi and Sugeno fuzzy system, adaptive neuro-fuzzy inference system, decision tree, radial basis function, extreme gradient boosting, least-squares boosting, least squares support vector regression and k-nearest neighbours, were trained for initial estimation. To improve the efficacy of stand-alone algorithms, their outputs were combined in CM structures using optimisation algorithms. This integration was applied through five optimisation algorithms, including genetic algorithm, ant colony, particle swarm, covariance matrix adaptation evolution strategy (CMA-ES) and Coyote optimisation algorithm. Considering the lowest error, the CM with CMA-ES showed superior performance. Subsequently, MVLR was employed to improve the CMs further. Employing MVLR to combine the CMs yielded a 57.85% decline in mean squared error and a 4.502% improvement in the correlation coefficient compared to the stand-alone algorithms. The results of the benchmark analysis validated the efficacy of this approach.
This paper presents short term load forecasting using multi-variable linear regression (MLR) for big data. Load forecasting is very important for planning, operation, resource scheduling and so on in power system. Tot...
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ISBN:
(纸本)9781538627266
This paper presents short term load forecasting using multi-variable linear regression (MLR) for big data. Load forecasting is very important for planning, operation, resource scheduling and so on in power system. Total electric demand dynamically changes in a power system and mainly depends on temperature, humidity, wind speed, human nature, regular activities, events, etc. input variables. For the help of sensors and data science, enough historical and future input data with good accuracy are easily available. On the other hand, linearregression is a proven method, widely used in industries for forecasting. It is deterministic and robust. However, it is slow for big data because it needs large size matrix operations. In this paper, linearregression is formulated for small number of variables with big data and multi-core parallel processing is applied in all matrix operations that allow unlimited historical big data and unlimited scenarios in acceptable execution time limit. Mean absolute percent error is 3.99% of real field recorded data shown in Simulation and Result section.
A single-fibre microfiltration system was employed to investigate the importance of various operating and sludge property parameters to the membrane fouling during sludge filtration. The sludge was obtained from a sub...
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A single-fibre microfiltration system was employed to investigate the importance of various operating and sludge property parameters to the membrane fouling during sludge filtration. The sludge was obtained from a submerged membrane bioreactor (SMBR). A series of comparative and correlative filtration and fouling tests were conducted on the influence of the operating variables, sludge properties and the liquid-phase organic substances on the membrane fouling development. The test results were analysed statistically with Pearson's correlation coefficients and the stepwise multi-variable linear regression. According to the statistical evaluation, the membrane fouling rate has a positive correlation with the biopolymer cluster (BPC) concentration, sludge concentration (mixed liquor suspended solids, MLSS), filtration flux and viscosity, a negative correlation with the cross-flow velocity, and a weak correlation with the extracellular polymeric substances and soluble microbial products. BPC appear to be the most important factor to membrane fouling development during the sludge filtration, followed by the filtration flux and MLSS concentration. The cross-flow rate also is important to the fouling control. It is argued that, during membrane filtration of SMBR sludge, BPC interact with sludge flocs at the membrane surface to facilitate the deposition of the sludge cake layer, leading to serious membrane fouling.
Experimental amino acid concentrations of blonde and black commercial beers, brewed in Argentina, as well as national malts were subjected for the first time to Quantitative Structure-Property Relationships (QSPRs). T...
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Experimental amino acid concentrations of blonde and black commercial beers, brewed in Argentina, as well as national malts were subjected for the first time to Quantitative Structure-Property Relationships (QSPRs). Thus, Dragon theoretical descriptors were derived for a set of optimised amino acid structures with the purpose of assessing QSPR models. We used the statistical Replacement Method for designing the best multi-parametric linearregression models, which included structural features selected from a pool containing 1497 constitutional-, topological-, geometrical-, and electronic-type molecular descriptors. In this work QSPR results were in good agreement with experimental amino acid profiles, thus demonstrating the predictive power of the designed QSPRs. QSPR-modelling was used to predict aminograms, and was also used to estimate non-available amino acid concentrations for these malts, and beers. The developed QSPR approach showed to be an useful tool for discriminating among blonde and dark beers, and malts. This is a new application of the QSPR theory to food, in particular to chemical biomarkers of malts and beers. (C) 2010 Elsevier Ltd. All rights reserved.
In the machining of small holes by the conventional micro abrasive jet machining, the colliding abrasives accumulate in the bottom of the hole, preventing the direct impact of successive abrasives onto the workpiece. ...
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In the machining of small holes by the conventional micro abrasive jet machining, the colliding abrasives accumulate in the bottom of the hole, preventing the direct impact of successive abrasives onto the workpiece. As a result, the machining efficiency decreases as the machining progresses. This paper introduces a new method of micro abrasive jet machining, called micro abrasive intermittent jet machining (MAIJM), in which there exists a period of time during which no abrasive is injected into the gas stream from the nozzle so that the continuous flow of gas without abrasives from the nozzle could blow away any abrasives that have accumulated in the hole. Empirical models are developed for evaluation of the effect of MAIJM process parameters on the shape of the machined holes by proper design of experiments based on a Taguchi orthogonal array and by multi-variable linear regression. Further experiments are conducted to confirm the validity of the developed statistical model by comparing the model predictions with the experimental results. (c) 2004 Elsevier Ltd. All rigts reserved.
The concentrations of the amino acids of Reggianito Argentino and Goya full-ripened industrial Argentine hard cheeses were subjected to quantitative structure-property relationship (QSPR) models. We used the statistic...
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The concentrations of the amino acids of Reggianito Argentino and Goya full-ripened industrial Argentine hard cheeses were subjected to quantitative structure-property relationship (QSPR) models. We used the statistical Replacement Method technique for designing the best multi-parametric linearregression models, which included structural features selected from a pool containing 1497 molecular descriptors. Predicted QSPR values were in good agreement with experimental amino acid profiles carried out in our laboratories. The developed approach is of practical value, especially to assign unknown analyte concentrations for Reggianito Argentino and Goya cheeses, and to establish whether any cheese sample belongs to these kinds of hard cheeses. (C) 2011 Elsevier B.V. All rights reserved.
Electrorheological fluid (ER fluid) is a functional fluid with the property that its viscosity can vary with the applied electric field strength. This paper investigates a polishing method using the electrorheological...
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Electrorheological fluid (ER fluid) is a functional fluid with the property that its viscosity can vary with the applied electric field strength. This paper investigates a polishing method using the electrorheological fluid, known as ER fluid-assisted polishing, for the finishing of micro dies of tungsten carbide alloy, which are used for the mass production of micro aspheric glass lens. The machining principle of the ER fluid-assisted polishing is introduced. By proper design of experiments based on a Taguchi orthogonal array and by multi-variable linear regression, empirical models are developed for evaluation of the effect of the process parameters on the material removal depth and surface roughness obtained in the ER fluid-assisted polishing. Further experiments are conducted to confirm the validity of the developed statistical model by comparing the model predictions with the experimental results and meanwhile the influences of the process parameters on the polishing performance are revealed. (c) 2005 Elsevier Ltd. All rights reserved.
Material loading is one of the most critical operations in earthmoving projects. A number of different equipment is available for loading operations. Project managers should consider different technical and economic i...
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Material loading is one of the most critical operations in earthmoving projects. A number of different equipment is available for loading operations. Project managers should consider different technical and economic issues at the feasibility study stage and try to select the optimum type and size of equipment fleet, regarding the production needs and project specifications. The backhoe shovel is very popular for digging, loading and flattening tasks. Adequate cost estimation is one of the most critical tasks in feasibility studies of equipment fleet selection. This paper presents two different cost models for the preliminary and detailed feasibility study stages. These models estimate the capital and operating cost of backhoe shovels using uni-variable exponential regression (UVER) as well as multi-variable linear regression (MVLR), based on principal component analysis. The UVER cost model is suitable for quick cost estimation at the early stages of project evaluation, while the MVLR cost function, which is more detailed, can be useful for the feasibility study stage. Independent variables of MVLR include bucket size, digging depth, dump height, weight and power. Model evaluations show that these functions could be a credible tool for cost estimations in prefeasibility and feasibility studies of mining and construction projects.
Dragon theoretical descriptors were derived for a set of optimised amino acid structures, with the purpose of establishing quantitative structure-property relationship (QSPR) models to predict aminograms for 100% natu...
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Dragon theoretical descriptors were derived for a set of optimised amino acid structures, with the purpose of establishing quantitative structure-property relationship (QSPR) models to predict aminograms for 100% natural fresh juices and concentrates of Navel and Valencia oranges, and Eureka lemon. We used the statistical replacement method technique for designing the best multi-parametric linearregression models, which included structural features selected from a pool containing 1497 constitutional, topological, geometrical, or electronic types of molecular descriptors. The prediction results achieved in this work were in most cases in good agreement with experimental amino acid profiles obtained in our laboratories by a validated HPLC procedure, thus demonstrating the predictive power of the designed QSPR. The developed approach is of practical value, especially when it is not possible to assign the analyte concentration with an accurate degree of certainty. (C) 2010 Elsevier Ltd. All rights reserved.
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