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The joint operation of cascaded reservoirs can generate various compensation benefits. How to calculate all compensation benefits scientifically and fairly, and how to share these benefits reasonably, will be of great importance for the sustainable development of the basin and for the rolling development of a cascaded reservoir of a hydropower station. This article examines the joint operation of Longyangxia and Liujiaxia reservoirs at the upper reaches of the Yellow River in China. To study the reservoir compensation benefits, the authors have built a compensative regulation model for the joint operation of the reservoir group. The electricity generation compensation economic effects of the joint operation of the Longyangxia and Liujiaxia reservoirs in 2005 were calculated. The results showed that the joint operation of cascaded reservoirs can generate remarkable economic benefits. [ABSTRACT FROM AUTHOR]

Remote sensing has been recognized as an effective tool to monitor water quality in inland waters. An adaptive model coupled with a modified discrete binary particle swarm optimization algorithm utilizing the catastrophe strategy and partial least squares (MDBPSO-PLS) was developed to retrieve the water quality indexes (chlorophyll a (chl- a ), total suspended matter (TSM), and turbidity) in Weishan Lake. Based on the selective bands for water quality retrieval, the proposed MDBPSO algorithm was compared with original DBPSO and Genetic Algorithm (GA) in order to validate the feasibility and efficiency of the proposed algorithm. The comparison results indicated that MDBPSO with the catastrophe strategy could avoid the premature convergence phenomenon of DBPSO algorithm. The hyperspectral data from HJ-1A Hyperspectral Imager (HSI) selected by MDBPSO were utilized to establish the PLS model by correlating the spectral data with measured water quality parameters. Then the established PLS model was compared with the PLS model established with full spectral data and measured water quality parameters. MDBPSO-PLS showed the better performance in retrieving the above-mentioned three parameters in Weishan Lake. The comprehensive errors between measured and retrieved parameters in MDBPSO-PLS (chl- a ( R 2  = 0.97, CE  = 3.16%), TSM ( R 2  = 0.97, CE  = 5.84%), and turbidity ( R 2  = 0.97, CE  = 7.40%)) were lower than those in PLS model (chl- a ( R 2  = 0.55, CE  = 18.71%), TSM ( R 2  = 0.49, CE  = 49.50%), and turbidity ( R 2  = 0.50, CE  = 50.46%). The three water quality parameters were mapped by using MDBPSO-PLS. Our observations indicated that the MDBPSO-PLS model showed the significantly higher retrieval accuracy than the PLS model and could provide realistic information on the distribution of chl- a , TSM, and turbidity in Weishan Lake based on HJ-1A HSI. [ABSTRACT FROM AUTHOR]

In order to ensure economic development, China plans to build fourteen large-scale coal bases during the period of the 13th Five-Year Plan (2015–2020). Coal production and washing, coal-fired power generation, and coal chemistry are the major developing industries in relation to the coal bases. In this study, we predict that by 2020, the newly increased water demand of these three industries will reach 3.8 billion m 3 . Even if water saving measures are reinforced, the newly increased water demand will still be 2.3 billion m 3 . Water resources will become the weak link, restricting the energy industry development of coal bases in areas such as Xinjiang, Ordos, Northern Shaanxi, and Huanglong. In addition, according to current plans, the scale of development for coal bases in water-deficient areas such as Northern Shaanxi, Huanglong, Shendong, Eastern Mongolia, Eastern Ningxia, and Xinjiang is expected to increase substantially. This will drive increased water demand, intensifying competition for water among different industries and regions in the context of a limited capability to guarantee regional water resources. Severe water resources challenge China’s energy development strategies is foreseeable, and if we are to guarantee the water supply required by these coal bases, it is necessary to begin expanding supply and controlling demand now. [ABSTRACT FROM AUTHOR]

This study analyzed the contributions of output, technological, and structural factors to industrial water use. Using Tianjin, a National Water-Saving City in China, as a case study, we adopted the refined Laspeyres and Logarithmic Mean Divisia Index models to decompose the driving forces of industrial water use changes. The decomposition results of both models show that output and technology have long-term, stable effects on industrial water use in Tianjin. Output stimulates water use, leading to an average annual growth of 7700 × 10 4 m 3 , while technology inhibits water use, with an average annual reduction of 7900 × 10 4 m 3 . However, the effects of structure on industrial water use are not stable. During the study period, the stimulation and inhibition of industrial water use alternated; however, stimulation was dominant after 2008, implying increased partiality of the industrial structure toward high water use. The results of the study contrasted the hypothesis that Tianjin's primary goal in restructuring local industries over the past decade has been the achievement of water use efficiency. Reduced water use may have resulted from Tianjin's development with targets other than water-savings. [ABSTRACT FROM AUTHOR]

To ease the growing water crisis, Tianjin has pioneered the implementation of the most stringent water management system in China. Presently, Tianjin achieves the highest industrial water efficiency in China. In 2010, Tianjin was named the first “Water-Saving Society Construction Demonstration City” by the Chinese central government. To provide a theoretical basis and supporting data for the construction of “national water-saving cities”, a decomposition method is adopted to quantitatively analyze changing industrial water use in Tianjin. Data are decomposed using a refined Laspeyres model, highlighting changes associated with industrial restructuring, followed by detailed sectoral analysis. There are two distinct stages of industrial water use: before 2008, industrial water use decreased, driven predominantly by technological advances; after 2008, higher industrial output led to greater industrial water use that overshadowed the water savings achieved by technological development. Nevertheless, water efficiency showed limited improvement, despite the increasing industrial scale and output of certain industrial sectors. The findings show that in Tianjin, reduced industrial water use is not the primary objective, but an associated combination of industrial development and structural adjustment. [ABSTRACT FROM AUTHOR]

At present, the urbanization and energy consumption complex system enters the stage of ultimate development. So it is not certain about synergistic development. From the perspective of causal feedback mechanism system and based on the mechanism of various elements of urbanization and energy consumption, this paper explores the path of synergistic development of urbanization and energy consumption, simulates the baseline scenario from 2005 to 2020 through establishment of the SD model of urbanization and energy consumption complex system, predicts the future behavior of the state variable when the control variable changes in the system through simulation, seeks for interaction and interrelationships between various elements in the process of evolution and development, and finally puts forward three paths to optimize the synergistic development of urbanization and energy consumption which are population transfer, industrial upgrading and technological improvement, which provides some references and foundation for making decisions of synergistic development of new urbanization and energy consumption. [ABSTRACT FROM AUTHOR]

Coal is China's most important primary energy source, and is supporting the rapid economic growth going on there. However, the reverse geographical distribution of coal production and consumption results in a high cost of coal transportation and low efficiency of coal utilization. To ease the pressure on coal transportation, and to mitigate pollution in eastern coastal regions, China has kicked off a strategic west–east transfer of energy industries that requires the movement of coal power projects to the arid northwest regions. Under this strategic framework, the regulation is focused on “clean production”, “consumption reduction” and “reuse”, rather than conservation and protection of water resources. This study found that the northwest areas are unable to accommodate fully the planned scale of coal-fired power industry. Moreover, the subsidiary chemical industry, even if the scale of electric power development is determined according to the need for coal production, is problematic because the current water demand for the coal industry has exceeded “allowed water withdrawal”. Given limited water saving potential and the huge demand-and-supply gap, it is also unrealistic to balance water demand by combination of water conservation in the power industry and water right diversion from agriculture. This study on the synergies between energy and water is urgently needed, in order to provide scientific and technological support for laying out new energy industries. A critical change should involve conciliation of conflicting policies or plans before implementation begins. [ABSTRACT FROM AUTHOR]

Abstract Intense vibrations in hydraulic turbine generator unit draft tubes lead to a run-out of the unit shafting and threaten its safe and stable operation. Correct maintenance is therefore important for the safe operation of such units. This study involves assessing the condition of the turbine generator unit by extracting the feature information of its vibration signals. Based on previous research, we present an enhanced Hilbert–Huang transform (HHT) method with an energy-correlation fluctuation criterion to extract feature information and effectively verify the method with simulated signals. An inspection application based on the signal from a vortex strip in the draft tube of a prototype turbine under suboptimal operating conditions indicates that this method is more effective than the traditional one, with a better component identification capability and better suited to the analysis of the complex and dynamic feature information of hydro turbines. Highlights • Intense vibration in hydraulic turbine generator unit draft tubes leads to a run-out of the shafting of the unit. • It assessed the condition of the unit by extracting information concerning its vibration signal features. • An enhanced Hilbert Huang Transform (HHT) method with an energy-correlation fluctuation criterion was used. [ABSTRACT FROM AUTHOR]

Calibrating the coefficients of discharge formulas of gates has great significance for the simulation and control of water flow. By investigating three discharge formulas derived from the energy equation and one discharge formula derived from dimensionless analysis of radial gates, the new parameter identification models for these discharge formulas were established using the least squares method, and the coefficients of discharge formulas were obtained. Followed by that, these discharge formulas of radial gates were applied through a case study. The results showed that the mean relative errors of the four formulas were 18.99%, 34.26%, 24.10% and 21.11%, respectively; while the mean relative errors were reduced to 3.54%, 3.54%, 1.90% and 1.09% by the use of parameter identification technique, respectively, indicating that the accuracy was greatly improved. The results proved that the parameter identification method may have potential application to improve the accuracy of calculating the discharge under the radial gates, and can also be applied to the sluice gates. [ABSTRACT FROM AUTHOR]

The presence of native adsorptive substances (NAS) cause uncertainties in the analysis of sediment phosphorus (P) adsorptive capacity. Therefore, HCl washing pretreatment is now used to clean sediment NAS. However, uncertainties still exist because the concentration ( C ) varies widely, from pH 3.5–12 mol/L, among studies. In this study, sediment samples from four sites were washed with HCl at different concentrations ( C ), and then analyzed to evaluate washing effects on the native absorptive substances (phosphorus, metals, and organic matter), the phosphorus equilibrium adsorption capacity (EAC), and sediment skeleton erosion. Study results reveal that washing efficiency, sediment skeleton erosion, and adsorption capacity varied with C . Micromorphology analysis showed that sediment erosion increased with increasing C ; the optimum C value is 0.0–1.0 mol/L (STG1) level based on its small negative impact on the sediment skeleton. Additionally, NAS analysis further showed that washing efficiency increased with increasing C . Most native adsorptive substances (NAP, Fe, Al, Ca, and OM) were released when the HCl concentration was in the range of 0.5–1.0 mol/L. Therefore, 0.5–1.0 mol/L (in STG1) may be the best choice for sediment washing because of its fairly satisfactory washing efficiency. Finally, P equilibrium adsorption capacity (EAC) analysis showed that the sorption capacity varied greatly with C at 0.5–1.0 mol/L, due to the erosion of the sediment skeleton. Therefore, C at 0.5 mol/L is the optimal concentration because the skeleton erosion was minimized when C decreased to the minimum point in the 0.5–1.0 mol/L range. The HCl washing pretreatment ( C = 0.5 mol/L) can also be used for analyzing other basic physicochemical substances (P, Ca, OM, Fe, Al). Our findings are an important step in providing important data for ecological restoration of wetlands, streams, rivers, lakes, and reservoirs, especially for those controlled by the internal source. [ABSTRACT FROM AUTHOR]

Optimizing energy structure to reduce carbon intensity is an effective way to build the low-carbon city development model. To assess the contribution potential of energy structure optimization in order to achieve the carbon intensity target in Hangzhou City, the component data prediction, scenario prediction, GMI (1, 1) model and other multidisciplinary approaches were adopted to predict the carbon intensity trends in the above said City from 2014 to 2020. This contribution potential is evaluated based on 9 kinds of combined scenarios. The results show that: 1. Under the same economic growth rate, with the increase in energy structure adjustment range, the carbon intensity “decline range” becomes larger, and the higher is the “contribution potential” of energy structure optimization to achieve the carbon intensity target. 2. Within the same range of energy structure optimization, the economic growth rate is lower, the carbon intensity “decline range” is smaller, and the “contribution potential” of energy structure optimization is higher for the same carbon intensity objective. By optimizing energy structure and industrial structures adjustment, the technology upgrading for carbon emissions and the scientific and technological level of the systematic industrial policies are more conducive to supporting the realization of low-carbon city. [ABSTRACT FROM AUTHOR]

In recent years, the optimization community has witnessed a surge in the popularity of population-based optimization methods. However, many of these methods suffer from various shortcomings, including unclear performance characteristics, incomplete validation, excessive reliance on metaphors, inadequate exploration and exploitation components, and compromised trade-offs between exploration and exploitation in real-world scenarios. As a result, users often find themselves needing to extensively modify and fine-tune these methods to achieve faster convergence, stable balance, and high-quality results. To shift the optimization community's focus towards performance rather than metaphorical changes, we propose a general population-based optimization technique called the Great Wall Construction Algorithm (GWCA). This study presents GWCA as a simple yet robust method with competitive performance for efficiently solving constrained and unconstrained problems. GWCA draws inspiration from the competition and elimination mechanisms observed among workers during the construction of the ancient Great Wall. It introduces a mathematical model of the labor movement to simulate the algorithm's dynamics. Unlike other methods that employ multiple models to generate new solutions, GWCA randomly assigns a single predefined motion model to each worker in every iteration. This unique approach showcases GWCA's dynamic nature, simple structure, high convergence performance, and ability to deliver satisfactory solution quality, thus outperforming existing optimization methods in terms of efficiency. To validate GWCA, we conduct extensive comparisons with popular and advanced algorithms on the IEEE CEC 2017 benchmark suite across different dimensions (D = 10, 30, 50, 100). Additionally, GWCA is applied to solve 16 constrained engineering problems and 6 NP-Hard problems, demonstrating its applicability in handling constrained and complex nonlinear problems. Finally, we compare GWCA's optimized solutions with those obtained from 33 advanced meta-heuristic algorithms, including the winner of CEC 2017. The results confirm the effectiveness of the proposed optimizer in solving a wide range of single-objective problems, surpassing popular base optimizers, advanced variants of existing methods, and several CEC winners. We present GWCA as an open-source population-based method that can serve as a standard optimization tool across various domains of artificial intelligence and machine learning. It exhibits a range of exploratory and exploitative features, offering high performance and optimization capabilities. The method is highly flexible, scalable, and can be further extended in terms of structure and application to accommodate diverse forms of optimization scenarios. https://github.com/guangian/Great-Wall-Construction-Algorithm-a-novel-meta-heuristic-algorithm-for-global-optimization. [ABSTRACT FROM AUTHOR]

The completion of Shuibuya, the last hydropower station to be constructed in the Qingjiang cascade, signifies China's successful development of the world's largest mixed cascade hydropower generation system. Joint operation of such cascaded hydropower stations is considered necessary to improve hydropower output in China. In this study, two modeling methods – routine and optimal operations – were adopted, based on existing rules of reservoir operation, to determine the effects of joint operation. To investigate the realistic and potential effects, the two models were computed using observed runoff data (1951–2009). The potential effects were identified by comparing the total hydropower generation two single cascades and their cogeneration. Under the routine operational mode, the incremental power generation of joint operation would be 5.73 × 10 8 kWh, an increase of 5‰ compared to isolated operation. However, even in isolation, if reservoir operation is optimized through the dynamic programming algorithm, the incremental power generation of the cascade would be 42.24 × 10 8 kWh, which is seven times that of joint operation with routine reservoir operation (5.73 × 10 8 kWh). The results showed that, under current reservoir operating rules, there is little room for improvement in hydropower generation, although joint operation could increase hydropower generation to a certain extent, especially in the reservoirs' refill and release stages. China must amend its existing operational mode for reservoirs to enhance the economic benefits of cascade hydropower stations. Furthermore, to meet increasing demands for both water and energy, carefully considered planning of constructing clusters of these stations is required. [ABSTRACT FROM AUTHOR]

China is a country with a serious water shortage. Irrigation water accounts more than 60% of total water use. With the nation’s population forecasted to peak approximately 2030, the production of food for additional people will require more water resources, which exacerbates water shortages. North China is a typical case for studying water-food nexus because water shortage has become a primary factor in restricting food production. From the perspective of virtual water, the study calculates the changing trend of the virtual water (VW) flow related to grain transfer in China, for which three primary crops of China, including rice, wheat and maize, are considered. The results demonstrate the impact of changing the spatial patterns of grain production on water resource utilization is large, and water resources are redistributed related to grain trade. Northern China imports water-intensive products from southern China and exports water-extensive products, and the VW flow from North to South from 2004 to 2013 was approximately 42.6 billion m 3 per year, about 10.2 billion m 3 irrigation water was transferred per year which accounts for about 10% of the water consumption for crop production in the North. Although the South–North Water Diversion Project, a mega-engineering scheme constructed from the Yangtze River Basin to the Huang-Huai-Hai River Basins, alleviates water pressure on the North to a certain extent, it is insufficient for exporting to provinces, and water resources for meeting grain production in the North is problematic. Based on the results, this paper suggests that virtual water flow among provinces should be linked to water resource management. The next step in water management should focus on water demand management, rather than increasing crop trade from the North to the South, which is governed by governmental policies and economy. [ABSTRACT FROM AUTHOR]