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In recent years, the frequent occurrence of air pollution incidents has seriously affected people's health and life. Therefore, PM 2.5 , as the main pollutant, is an important research object of air pollution at present. Effectively improving the prediction accuracy of PM 2.5 volatility makes the PM 2.5 prediction content perfect, which is an important aspect of PM 2.5 concentration research. The volatility series has an inherent complex function law, which drives the volatility movement. When machine learning algorithms such as LSTM (Long Short-Term Memory Network) and SVM (Support Vector Machine) are used for volatility analysis, a high-order nonlinear form is used to fit the functional law of the volatility series, but the time-frequency information of the volatility has not been utilized. Based on EMD (Empirical Mode Decomposition) technique, GARCH (Generalized AutoRegressive Conditional Heteroskedasticity) model and machine learning algorithms, a new hybrid PM 2.5 volatility prediction model is proposed in this study. This model realizes time-frequency characteristic extraction of volatility series through EMD technology, and integrates residual and historical volatility information through GARCH model. The simulation results of the proposed model are verified by comparing the samples of 54 cities in North China with the benchmark models. The experimental results in Beijing showed that MAE (mean absolute deviation) of hybrid-LSTM decreased from 0.00875 to 0.00718 compared with LSTM, and hybrid-SVM based on the basic model SVM also significantly improved generalization ability, and its IA (index of agreement) improved from 0.846707 to 0.96595, showing the best performance. The experimental results show that the hybrid model is superior to other considered models in terms of prediction accuracy and stability, which verifies that the hybrid system modeling method is suitable for PM 2.5 volatility analysis. [ABSTRACT FROM AUTHOR]

In the study, a comprehensive transient fuel cell-battery hybrid power system model is established to explore the output performances and dynamic responses of fuel cell electric vehicles (FCEVs). A fuel cell system sub-model, a one-dimensional transient Li-ion battery sub-model, two direct current/direct current (DC/DC) sub-models as well as a vehicle load sub-model are integrated. The coupled heat and mass transfer processes are considered inside fuel cell system and Li-ion battery. After rigorous model validation, the overall performances under several typical China standard vehicle road conditions are investigated, including power distribution between different power units, battery state of charge (SOC), battery charge/discharge rate, fuel cell operating duration, temperature, and other key parameters. During the 100 km h−1 acceleration processes under the preliminary rule-based energy management strategy (EMS), the accelerated speed is found to be the largest in the beginning, resulting in the fact that the discharge power for battery increases sharply. The shorter the acceleration time, the larger the maximum power demand for Li-ion battery. During the combined 1300 s high-speed operating conditions under the on-off switch EMS, the total operating duration of fuel cell system is calculated to be about 531 s, and the total output power is calculated to be 11,556 kJ. In comparison, the vehicle saves about 1044 kJ energy and increases the fuel cell operation duration by 333.7% under the power-following EMS. The present study provides important guidance in terms of dynamic simulation analysis and energy management strategy for FCEVs. [ABSTRACT FROM AUTHOR]

In recent times, there has been a growing demand for the use of biomass as an alternative energy due to its sustainable nature. At present, anaerobic digestion and gasification has been proven as a promising technology for exploiting this energy from biomass. This review aims to provide a comprehensive and detailed analysis of the combination of anaerobic and gasification technology as a hybrid system for sustainable waste-to-energy generation. This review reveals that both anaerobic digestion and biomass gasification have been successfully demonstrated as technologies for energy recovery. However, to improve the conversion efficiency in both technologies, the utilization of an intensifier, additive, and enhancer will be required. Moreover, temperature has been identified as a major factor affecting the technologies and should be considered. The bibliometric study conducted revealed that China is the leading country and has set the pace for other countries to follow suit. Subsequently, waste-to-energy research could be easily implemented on a global scale. This study recommends an experimental study of anaerobic digestion and gasification as a hybrid system. [ABSTRACT FROM AUTHOR]

With the sharply increased development of variable renewable energy resources (VRERs) in recent years, the hydro-wind-photovoltaic (PV) hybrid system (HWPHS) has the prospective to enhance the grid integration of VRERs. Nevertheless, the intense variation associated with wind and PV generation causes uncertainties in the long-term operation of the HWPHS. To overcome this drawback, this paper develops a novel method to derive adaptive operating rules for a cascade HWPHS. First, a scenario-generating method coupling Kernel density estimation with the copula function is proposed to characterize the wind and PV forecast errors. Second, based on the power generation scenarios, an optimal scheduling model for the cascade HWPHS considering transmission section constraints is proposed to simulate the hydro-wind-PV complementary operation; finally, the long-term operating rules for the cascade HWPHS are extracted by grey relational analysis and BP neural network. As a case study, the HWPHS of the Wu River basin in China is chosen. Results demonstrate that the proposed model can effectively utilize the flexibility of cascade hydropower stations, improve transmission section utilization efficiency, and promote clean energy absorption. [ABSTRACT FROM AUTHOR]

The issue of renewable energy curtailment poses a crucial challenge to its effective utilization. To address this challenge, mitigating the impact of the intermittency and volatility of wind and solar energy is essential. In this context, this paper employs scenario analysis to examine the complementary features of wind and solar hybrid systems. Firstly, the study defines two types of complementary indicators that distinguish between output smoothing and source-load matching. Secondly, a novel method for generating wind and solar output scenarios based on improved Generative Adversarial Networks is presented and compared against the conventional Monte Carlo and Copula function methods. Lastly, the generated wind and solar scenarios are employed to furnish complementary features. The testing results across eight regions indicate the proposed scenario generation method proficiently depicts the historical relevance as well as future uncertainties. This study found that compared to the Copula function method, the root mean square error of the generated data was reduced by 4% and 3.4% for independent and hybrid systems, respectively. Moreover, combining these two resources in most regions showed that the total output smoothness and source-load matching level cannot be enhanced simultaneously. This research will serve as a valuable point of reference for planning and optimizing hybrid systems in China. [ABSTRACT FROM AUTHOR]

Cytoplasmic male sterility (CMS) is the main mechanism employed to utilize the heterosis of Brassica napus. CMS three-line rapeseed hybrids have dramatically enhanced yield and brought about the global revolution of hybrid varieties, replacing conventional crop varieties. Over the last half century, China has led the development of hybrid Brassica napus varieties. Two sterile lines, polima (pol) and shaan 2A, were of particular importance for the establishment of three-line hybrid systems in rapeseed, which has opened up a new era of heterosis utilization. However, in current breeding practices, it takes up to three years to identify the restorer or maintainer relationship and the cytoplasmic type of any inbred material. This greatly affects the breeding speed of new varieties and inhibits the rapid development of the rapeseed industry. To address this problem, we developed a set of molecular markers for the identification of fertile cytoplasmic gene N and sterile cytoplasmic gene S, as well as for the fertile nucleus gene R and sterile nucleus gene r, based on differences in the gene sequences between the CMS line, maintainer line and restorer line of Brassica napus. Combining these markers can accurately identify the CMS line, maintainer and restorer of both the pol and shaan systems, as well as their hybrids. These markers can not only be used to identify of the maintainer and restorer relationship of inbred materials; they can also be used as general molecular markers to identify the CMS-type hybrid purity of pol and shaan systems. [ABSTRACT FROM AUTHOR]

The traditional long-term operation models of hydro–photovoltaic (PV)–wind hybrid systems (HPWHSs) were formulated on the basis of monthly or ten-day time-scale, and they failed to describe intraday stochastic and fluctuating features of the PV and wind power, resulting in sub-optimal operating rules. To address this issue, we proposed an effective method to refine long-term operating rules for the large HPWHS by nesting a set of response functions. These response functions were derived based on numerous daily operation results, characterizing relationships between long-term hydropower output and residual load, operational risk, and electricity curtailment metrics, respectively. A large HPWHS located in the upper Yellow River basin, Qinghai province, China was selected as a case study. Results showed that the refined operating rules could decrease curtailment rate of the new energy from 17.5% to 9% compared with a standard operation policy. Meanwhile, energy production of the HPWHS and its generation guaranteed rate were increased by 7.7% and 72.7%, respectively, and the residual load fluctuation and operational risk rate were reduced by 35.6% and 23.3%, respectively. Therefore, the proposed long-term operation method is effective for guiding the complementary management of the large HPWHS. [ABSTRACT FROM AUTHOR]

Hydro-wind-photovoltaic hybrid systems gain profit by bidding in the forecast lead-time. However, the literature focuses on bidding strategy to maximize current profits, while the future utilities (beyond forecast time) for hybrid systems are generally neglected. To address the research gap, the study proposed an integrated bidding strategy for a hydro-wind-photovoltaic hybrid system with a trade-off between current profits and future utilities considered. Steps are as follows: (1) ensemble forecasts are used within the forecast lead-time, within historical data input as stochastic scenarios beyond forecast time, (2) functional forms between the profit beyond forecast time and the reservoir carryover storage, expected price, inflow, wind and photovoltaic power are fitted, and (3) a two-layer nested bidding model is to maximize the total-profit. With China's Sichuan province as the market, the Jinping-I hybrid system was selected as the case study. Results show that: (1) profits beyond forecast time can be quantified as a linear function with R-squared for 10-day above 0.6, and (2) the optimal bidding strategy raises the profit by 0.45% while reduces water-consumption by 10.3% compared with conventional strategy. The framework is effective in gaining more profit with lower risk for hybrid systems. [ABSTRACT FROM AUTHOR]

Environmentally friendly and pollution-free hydrogen cell, battery and supercapacitor hybrid power system has taken the attention of scientists in recent years. Several notable advancements in energy storage mechanisms with hybrid power systems have been made during the last decade, influencing innovation, research, and the possible direction for improving energy storage technologies. This paper represents a quantitative analysis of all knowledge carriers with mathematical and statistical methods of hydrogen energy storage to establish a hybrid power system. For selecting the top cited papers in this topic, related articles on energy storage mechanisms for hybrid power systems were searched in the Scopus database under specified predetermined parameters. The selection technique of the most cited paper was based on filtered keywords in the hybrid hydrogen energy storage-based hybrid power system and related research during 2008–2021. About 48% of all articles have been published between 2016 and 2019; 21% will have originated from China; and 29% of the papers have used batteries as a form of energy storage in the application of electric vehicles. Most of the articles contain experimental work (25.11%) followed by simulation analysis (25%) and systematic and nonsystematic review (18.75%). Related publications with the most citations were published in 35 different impactful journals from different publishers and nations. This research found that integrating hydrogen energy storage with battery and supercapacitor to establish a hybrid power system has provided valuable insights into the field's progress and development. Moreover, it is a thriving and expanding subject of study. Bibliometric analysis was used to identify the most significant research publications on the subject of hybrid energy storage, mapping the multidisciplinary character, illustrating nature and trends, and outlining areas for further research. The process of collecting, selecting, and analyzing the most cited articles is expected to contribute to a methodical foundation for future developments of hydrogen energy storage systems and provide viable research paths toward attaining a hybrid power system. • Hydrogen-battery-supercapacitor hybrid power system made notable advancements. • A statistical analysis of hydrogen storage integrated hybrid system is demonstrated. • Top cited papers were searched in Scopus database under predetermined parameters. • Challenges and recommendations are highlighted for future energy applications. • Bibliometric analysis was used to identify potentials for future research directions. [ABSTRACT FROM AUTHOR]

• Absorption subcooling CO 2 refrigeration system driven by solar energy & waste heat. • Optimize thermodynamic performance and assess carbon emission of systems. • Effect of maldistribution of solar radiation and ambient temperature is discussed. • Annual performance factor and life cycle carbon emissions are evaluated in cities. • Hybrid absorption subcooling shows better performance in hot and solar rich areas. A novel hybrid solar energy and waste heat driving absorption subcooled carbon dioxide (CO 2 /R744) booster refrigeration system (SE + WH) is proposed to improve the energy efficiency of the traditional CO 2 refrigeration system used in supermarkets. The thermodynamic and energy conversion model of the system is established. Then, the optimization method of the two-dimensional golden section search algorithm is introduced to optimize the system energy efficiency taking the variation of ambient temperature and solar radiation intensity into account. Moreover, considering the maldistribution of solar energy and the influence of meteorological conditions in China, eight typical cities are selected to assess the annual performance factor and life cycle carbon emissions to achieve energy saving and carbon emission potentials. The performance of hybrid solar energy and waste heat driving absorption subcooled CO 2 booster refrigeration system is the best with the COP enhanced by 3.05–42.30 % at the solar radiation intensity of 1200 W/m2 and the temperature of 0–35 °C in contrast to the baseline system. In addition, the discharge pressure of the new proposed hybrid system can be reduced by 7.86 % when the ambient temperature is 34 °C. The annual performance factor of the new proposed hybrid system in Haikou can be increased by 14.47 %, and the life cycle carbon emissions are effectively reduced by 39.54 %. The payback period is also reduced by 4.01 % and 3.37 % for Beijing and Shanghai. Consequently, the novel configuration of the hybrid absorption subcooling subsystem is recommended, particular in hot or warm climate areas with rich solar energy. [ABSTRACT FROM AUTHOR]

Hydropower is utilized to regulate the fluctuations of wind and photovoltaic (PV) power in the hydro-wind-PV renewable energy system (H-RES), which can effectively improve energy utilization. However, it is challenging to determine the optimal capacity configuration considering power delivery and power output characteristics simultaneously. This study launched a research framework for determining the optimal capacity configuration and short-term coordinative operation rules considering the ultra-high voltage (UHV) transmission and reservoir operation requirements. Firstly, a scenario analysis technique was proposed to generate joint wind-PV scenarios considering the uncertainties and correlation. Secondly, a two-stage adaptive complementary operation strategy was presented. Subsequently, a nested mathematical model of capacity configuration and coordinated operation optimization of H-RES was established. Finally, the framework was applied to a case study in Qinghai Province, China. The results show that: (1) it is recommended the H-RES wind-PV penetration rate should not exceed 50% when the system is configured; (2) the proposed model and strategy can eliminate hydropower abrupt fluctuations by 32.7% on average; (3) the power grid role of the H-RES varies by season and it shows great potential of bearing the baseload in summer and autumn. Therefore, this research is instructive in the planning and actual operation of the large-scale H-RES. [ABSTRACT FROM AUTHOR]

With the continuous development of the times, the educational concept in the information age continues to advance, in order to meet the needs of the society, each school in China has reformed and piloted according to its own situation to improve the quality of teaching. The research of conventional mixed physical education teaching, from the perspective of research methods, can be divided into two orientations: qualitative and quantitative. On the other hand, from the perspective of sample size, traditional research is a small sample study, and these objective behavioral data have opened up a new perspective for the research of blended physical education teaching from the research methods and research content. In this context, this paper combines the fuzzy comprehensive evaluation method to propose fuzzy comprehensive evaluation methods for mixed physical education teaching, such as preclass preparation, in-class links, teaching content, and teaching methods and designs an online and offline hybrid teaching mode for physical education courses based on a fuzzy comprehensive evaluation to construct an evaluation system, determine its fuzzy operators, determine indicators, and evaluate them comprehensively, reasonably and accurately through experiments. The fuzzy comprehensive evaluation method is based on the fuzzy mathematics comprehensive evaluation method, which can evaluate the evaluation object from all aspects, can objectively reflect the essential characteristics of things, and the evaluation process of the mixed mode construction of physical education courses is more scientific and reasonable. The application of the fuzzy comprehensive evaluation method has effectively promoted the reform and improvement of education and provided a foundation for the continuous improvement and innovation of students' learning and teachers' teaching effects. [ABSTRACT FROM AUTHOR]

• Employing the combinations of short- and long-duration energy storage is assessed. • Equipping with both batteries and thermal energy storage outperforms in economy. • Integrating concentrated solar power is advised in good solar resource regions. • Hydrogen storage demonstrates reduced energy waste under high reliability. • The optimal system combination is influenced by the maximum capacity limits. Renewable energy generation systems typically exhibit variable output. The integration of short- and long-duration energy storage systems is the strategy to reconcile the discrepancy between renewable energy generation and load demand. This investigation aims to evaluate the feasibility of utilizing combinations of short- and long-duration energy storage under diverse conditions. The study involves energy generation systems incorporating photovoltaic arrays, wind turbines, batteries, hydrogen storage, thermal energy storage, and concentrated solar power components. The analysis covers 12 distinct regions within China, each paired with two distinctive demand profiles. The optimal capacity for each system's components was determined to minimize the levelized cost of energy (LCOE) while maintaining a loss of power supply probability (LPSP) of 1 %. Subsequently, the energy waste and environmental performance of the optimized system were examined. Additionally, the impact of maximum component capacity limitations on the optimal system configuration was investigated. Results indicate that systems equipped with both batteries and thermal energy storage outperform those paired with batteries and hydrogen storage in terms of economic performance under the LPSP of 1 % constraint. Moreover, the inclusion of a concentrated solar field proves to be economical in regions with ample solar resources. When calibrated to capacities that yield minimal LCOE while ensuring exceptional power supply reliability, the benefits of reducing energy waste with a battery and hydrogen storage configuration become pronounced. For installations where the capacity of generation components does not exceed 600 MW, a system integrating battery and hydrogen storage demonstrates superior economic performance in regions with abundant wind resources. [ABSTRACT FROM AUTHOR]

• The complementarity in the PV-wind-hydropower-hydrogen system is investigated. • Both PEMEL and AEL are integrated to significantly improve the economic benefits. • A novel simultaneous design and scheduling optimization model is proposed. • Cold/warm start-up behaviors and load range for various electrolyzers are considered. • Big-M linearization method is used to reduce the computational complexity greatly. Hydrogen production through both proton exchange membrane (PEM) and alkaline water electrolyzers provides a potential solution for enhancing electricity utilization in the photovoltaic (PV)-wind-hydropower system. This study proposes a novel simultaneous design and scheduling optimization model for the PV-wind-hydropower-hydrogen hybrid system. The detailed operating characteristics and constraints of both PEM and alkaline water electrolyzers, including cold/warm start-up and load range, are investigated to enhance the reliability of the optimization model. The Big-M method is utilized to convert the original optimization model into a mixed integer linear programming model for reducing the computational complexity. Finally, a case study in the Yalong River basin of China is employed to demonstrate the effectiveness of the proposed approach. The results illustrate that the coordinated scheduling among the hydropower station and electrolyzers could significantly improve the comprehensive performance of the hybrid system. Integrating PEM and alkaline electrolyzers could improve the economic benefits by 73.32% and 53.02%, respectively, compared to employing a single PEM and alkaline electrolyzer. It is thus indicated that the proposed approach could provide a promising solution for the optimal design and scheduling of PV-wind-hydropower-hydrogen hybrid systems. [ABSTRACT FROM AUTHOR]

Construction of the linearized state-space model is the key step of eigenvalue analysis for SSO study of power systems with large-scale renewable power generation (RPG) integrated. This paper proposes a novel method to construct the state matrix of the AC/DC hybrid power system with RPG within the discrete-time domain. The continuous-time state-space model of each AC/DC component as well as RPG units in the power system, is discretized together with their corresponding control. The discretized equation of each component is then represented by an equivalent circuit consisting of parallel historical current and conductance. According to the power system configuration, the discrete-time equivalent circuit of the whole AC/DC hybrid system is established, and the nodal analysis method is applied for the construction of the discrete-time state-space model of the power system. In this way, the state matrix can be acquired much more conveniently than that of continuous-time state-space method, which needs topology analysis to find independent state variables of the network from the proper tree. The proposed method has been applied in the eigenvalue analysis for the SSO study of a case system adapted from the AC/DC hybrid transmission system in northwest China. Eigenvalue results are in high accordance with time-domain simulation results in PSCAD/EMTDC. [ABSTRACT FROM AUTHOR]

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Water level prediction is vital in developing a sustainable conceptual design of water infrastructures, providing flood and drought control measures, etc. However, due to the complexity and many other inter-related influencing factors within a catchment, water level prediction remains a challenging task. A reliable method that is able to extract the non-linear behaviors of various parameters effectively, and thus enhances the modelling capability in terms of computation time and accuracy is required. Therefore, the Dongting Lake of China, a large-scale river–lake system has been selected for this study. The main aim is to provide a practical method for advanced water level prediction at the downstream outlet of Dongting Lake for flood warning purposes. The novelty of this study is the adoption of a soft computing modelling approach, based on minimum input requirements to reduce its dependency on too many inputs which might limit its functionality in the future. The results obtained show that the model developed can predict the hourly water level in Dongting Lake accurately with an error of 1.2%. It is able to provide an advanced water level prediction of 21 h ahead of the time step, and thus applicable for early flood warning to the surrounding area with densely populated townships. [ABSTRACT FROM AUTHOR]

The variation principle widely used in structural dynamics analysis allows us to transform the differential equation of the boundary value problem into a functional with extreme value. In recent years, it has been applied to the band-gap analysis of periodic structures. However, for periodic beam-plate composite structures with periodic and ordinary boundaries, it is relatively difficult for the traditional energy methods, such as the Rayleigh–Ritz method, to construct the displacement functions that satisfy boundary conditions. Hence, a hybrid solution is proposed in this paper to account for various boundary conditions of the periodic beam-plate composite structure. Specifically, the displacement functions constructed by the plane wave series can automatically satisfy the periodic boundary conditions. With the ordinary boundaries modeled by artificial springs, the spectral functions conforming to arbitrary boundary conditions are used to represent the displacement functions. The proposed solution is used to solve the band-gap problems of CRTS-III and CRTS-II slab ballastless tracks in China, and the accuracy of the solution is verified by comparing the calculated results with numerical simulations. In addition, through band-gap formation mechanism analysis, the frequency range of propagating flexural waves in each track component is accurately evaluated, which provides a theoretical basis for refined structural vibration reduction in the future. The solution proposed in this paper is flexible and convenient, which can be extended to a more complex band-gap analysis of periodic structures. [ABSTRACT FROM AUTHOR]

The multi-terminal hybrid LCC/MMC HVDC has been applied to overcome the simultaneous commutation failure problem caused by the multi-infeed LCC-HVDCs in the East China. The high-speed and selectivity line protection method is required for the multi-terminal hybrid HVDC system. In this paper, the reflection and refraction of the fault traveling waves at different kinds of line terminals are characterized by transfer functions. Then the fault voltage as well as its first peak time at different line terminals when different internal and external faults occur are derived respectively. The conclusion proves that the first peak time of line-mode fault component voltage (FPTV) for internal faults is smaller than that for external faults, which is independent of fault impedance and fault type as well. Therefore, a FPTV-based non-unit ultra-high-speed dc line protection method is proposed. The algorithm is implemented in the developed protection prototype and validated in the Kun-Liu-Long three-terminal hybrid HVDC RTDS test system. The test results show that the proposed method can fast and correctly identify line faults in the multi-terminal hybrid HVDC system, even with 500 Ω fault impedance. Comparing with the traveling wave protection method of ABB, the proposed method improves the sensitivity when high-impedance faults occur. [ABSTRACT FROM AUTHOR]

Wind and solar power are expected to play important roles in many countries to achieve carbon neutrality; however, their inherent instabilities pose significant threats to existing power grids. Because hydropower has been recognized as a viable compensatory resource for solar and wind energy uncertainties, many studies have sought to determine optimal scheduling strategies for hydro-PV, hydro-wind, and hydro-PV-wind systems. However, few studies have simultaneously considered the sizing and scheduling of large-scale hydro-PV-wind hybrid systems connected to long-distance transmission lines. Therefore, this paper develops a mathematical metric to measure the wind and solar output complementarity and incorporates it into a multi-objective sizing and scheduling model for a hybrid hydro-PV-wind system, in which resource complementarity, profit generation, system reliability, and power curtailment trade-offs are concurrently considered. The ɛ -constraint method is employed and decision makers' attitude parameters are introduced to transform the proposed model into its equivalent single objective form. A case study in China reveals that the maximum wind and solar power output complementarity rate can be at least 0.19 for the studied hybrid hydro-PV-wind system. The incorporation of wind enables the hybrid hydro-PV-wind system to provide 4.11% more load than a hydro-PV system. In addition, if 2% of power curtailment is permitted, 1.53% more load can be served and 14.9% higher profits can be earned. To better explore the application of hybrid systems, management recommendations are provided for system operators, the power industry, and management administrations. • Multi-objective sizing and scheduling method for the hybrid renewable system is proposed. • Mathematical metrics to measure wind and solar power complementarity is provided. • A complementarity rate of 0.19 can be reached with 100% reliable service and no curtailment. • Integrating wind power into the hydro-PV system can reliably serve 4.11% more load. • An optimal rather than minimal level of the renewable power curtailment is more efficient. [ABSTRACT FROM AUTHOR]

Photovoltaic module (PVM) only can utilize visible and ultra-violet parts of solar spectrum, constrained by the Shockley-Queisser limit. To fully use solar spectrum, in this study, solar selective absorber (SSA) and elastocaloric cooler (ECC) are gradually hybridized with PVM to form a new hybrid system for the first time. The performance metrics of PVM, ECC, and hybrid system, taking into account various irreversible effects, are mathematically derived. The hybrid system achieves approximately a 63% enhancement in both energy efficiency and power output density compared to a standalone PVM, outperforming other similar PVM-based hybrid systems. Exhaustive parametric studies show that increasing the operating temperature, solar irradiance, diode ideality factor, length ratio or section area ratio can enhance the hybrid system performance. The optimal combination of refrigerant and actuator materials are, respectively, Ni–Ti and Cu–Zn–Al alloys. Furthermore, a case study conducted to forecast practical performance under southeast China's weather conditions reveals that the hybrid system attains significant annual maximum energy efficiency and power output density, reaching 29.3% and 54.66 W m−2, respectively. The findings from this study provide valuable insights and recommendations for the optimum design and operation for such a hybrid system. • A new photovoltaic/thermal/elastocaloric hybrid system is theoretically developed. • The models of hybrid system and each subsystem are described and validated. • The hybrid system design can gain a 63% enhancement in energy efficiency. • Exhaustive parametric analyses on the performance of hybrid system are conducted. • A case study predicts the practical performance based on local weather conditions. [ABSTRACT FROM AUTHOR]

The settlement and deformation monitoring for existing tunnels would encounter the difficulties in sensor installation and health evaluation in real time. Thus, it is necessary to develop effective methods for settlement and deformation measurements in the existing tunnels. This study proposed a more practical tunnel deformation monitoring theory and developed remote wireless tunnel deformation real-time monitoring and early warning system based on infrared laser ranging technology and cable sensing technology. The system could monitor the settlement and deformation of the tunnel in real time from a long distance and transmit the deformation data wirelessly in real time; then, three-dimensional space model of tunnel deformation was established, which intuitively and comprehensively reflected the actual deformation of the tunnel and intelligently identified the deformation. Finally, based on the practice of deformation control during tunnel excavation at Xiaohongshu Station of Wuhan Metro Line 8 of China, the measurement results of this new method were compared with the measurement results of particle image velocimetry technology (PIV), the reliability of the new tunnel deformation monitoring method was proved, the settlement error of each monitoring point was found to be less than 1 mm, and the deformation trend was consistent with the actual deformation. The results of this research could provide useful guidance for tunnel deformation monitoring. [ABSTRACT FROM AUTHOR]

Background: Harnessing heterosis is one of the major approaches to increase rice yield and has made a great contribution to food security. The identification and selection of outstanding parental genotypes especially among male sterile lines is a key step for exploiting heterosis. Two-line hybrid system is based on the discovery and application of photoperiod- and thermo-sensitive genic sensitive male sterile (PTGMS) materials. The development of wide-range of male sterile lines from a common gene pool leads to a narrower genetic diversity, which is vulnerable to biotic and abiotic stress. Hence, it is valuable to ascertain the genetic background of PTGMS lines and to understand their relationships in order to select and design a future breeding strategy. Results: A collection of 118 male sterile rice lines and 13 conventional breeding lines from the major rice growing regions of China was evaluated and screened against the photosensitive (pms3) and temperature sensitive male sterility (tms5) genes. The total gene pool was divided into four major populations as P1 possessing the pms3, P2 possessing tms5, P3 possessing both pms3 and tms5 genes, and P4 containing conventional breeding lines without any male sterility allele. The high genetic purity was revealed by homozygous alleles in all populations. The population admixture, principle components and the phylogenetic analysis revealed the close relations of P2 and P3 with P4. The population differentiation analysis showed that P1 has the highest differentiation coefficient. The lines from P1 were observed as the ancestors of other three populations in a phylogenetic tree, while the lines in P2 and P3 showed a close genetic relation with conventional lines. A core collection of top 10% lines with maximum within and among populations genetic diversity was constructed for future research and breeding efforts. Conclusion: The low genetic diversity and close genetic relationship among PTGMS lines in P2, P3 and P4 populations suggest a selection sweep and they might result from a backcrossing with common ancestors including the pure lines of P1. The core collection from PTGMS panel updated with new diverse germplasm will serve best for further two-line hybrid breeding. [ABSTRACT FROM AUTHOR]

Renewable and carbon free energy relates to the sustainable development of human beings while hydrogen production by renewables and hydrogen underground storage ensure the stable and economic renewable energy supply. A hybrid energy system combining hydrogen production by offshore wind power with hydrogen storage in depleted oil reservoirs was constructed along with a mathematical model where the Weibull distribution, Wind turbine power function, Faraday's law, continuity equation, Darcy's law, state equation of real gas, Net Present Value (NPV) and the concept of leveling were adopted to clarify the system characteristics. For the case of a depleted oil field in the Bohai Bay, China, the annual hydrogen production, annual levelized cost of hydrogen and payback period are 2.62 × 106 m³, CNY 34.6/kgH 2 and 7 years, respectively. Sensitivity analysis found that the wind speed impacted significantly on system NPV and LCOH, followed by hydrogen price and stratum pressure. • A novel hybrid energy system for hydrogen production and storage was built. • The hydrogen was produced by offshore wind while stored in the depleted reservoir. • The H 2 production and CO 2 reduction were 2.6 × 106 m³ and 6.9 × 105 kg annually. • The system NPV and payback period were CNY 1.1 × 108 and 7 years. • Wind speed, H 2 price and stratum static pressure impacted the most on system NPV. [ABSTRACT FROM AUTHOR]

The renewable energy hybrid generation system in the area with renewable energy and land source plays a key role in improving the application of the renewable energy in China, with the rapid development of the extra high voltage (EHV) and ultra‐high voltage (UHV) grids to transmit the electricity. The suitable plan and decision‐making mechanism has a significant influence on the utilization of the renewable energy. The output of thermal power, wind power and photovoltaic are respectively simulated in the plan period of a hybrid generation system, and then all the output are comprehensively studied with the consideration of some constrains. However, the experience of the applications of the renewable energy hybrid generation system with thermal power revealed an obvious disadvantage that to maintain the competitiveness of the power output without the guidance of the price signals in the electricity market is difficult. The dispersed areal distribution and discontinuous power output of the renewable energy may be responsible for this disadvantage. The investigation to improve the consumption of the renewable energy hybrid generation system is meaningful to solve the renewable energy curtailment problems. In the present study, the investigation to the operation of a thermal‐wind‐photovoltaic hybrid generation system with market mechanism was conducted to optimize the consumption of the renewable energy. These results are beneficial to the operations of the similar hybrid generation systems. [ABSTRACT FROM AUTHOR]

To take full advantage of the complementary characteristics of various renewable energy sources, hybrid generation systems (HGSs) are used to accommodate the increased variability and uncertainty. In southwest China, there are many small cascade hydropower stations (CHSs) and PV power stations, which have spatial and temporal correlation characteristics and complementary characteristics. Pumped-storage units are considered as ideal large-scale energy storage elements for HGSs due to their fast response and long life. The purpose of this study is to increase the system reliability and water power utilization rate and maximize the economic benefits of a cascade hydro-PV-pumped storage (CH-PV-PS) generation system. Considering the reliability, economy, and water power utilization rate of the system, the CH-PV-PS system model with multiple objectives and multiple constraints is established. Then, a multi-objective stochastic numerical P system (MOSNP) is proposed. The external storage set and correction method in the MOSNP algorithm are introduced to ensure the diversity of the solution and improve the efficiency of the algorithm. The CH-PV-PS system is introduced in Sichuan Province, Southwest China. The simulation results show that (1) the MOSNP method can obtain robust and effective optimization results for the hybrid system; (2) the use of pumped storage units has increased the daily economy by 1018 CNY, and the total fluctuation of CHSs has been reduced by 29.3%, which makes the hybrid system safer and more economical; and (3) the uncertainty of PV and runoff will lead to frequent dispatching of CHSs, thus reducing the economic benefits of the system. [ABSTRACT FROM AUTHOR]

Building on research on hybridization, this study integrates the cultural and political perspectives to investigate the hybrid HR system of foreign-invested enterprises (FIEs) in China's emerging economy. Conceptualizing the hybrid system as an innovative adaptation based on selective adoptions of international and local management practices, we develop a cultural-political duality argument and consider both external-cultural conditions and internal-political processes in affecting the emergence and effectiveness of the hybrid HR system. Drawing on quantitative evidence from original survey data, we find that the cultural distance between a FIE's home and host countries exerts a U-shaped curvilinear effect on the emergence of a hybrid HR system. Moreover, a FIE with more balanced internal power structures is more likely to adopt a hybrid HR system. Finally, a hybrid system significantly enhances HRM effectiveness. As the hybrid system serves as a valuable alternative to the foreign and local models, our theoretical framework and findings have broad theoretical significance and important practical implications in international business management. [ABSTRACT FROM AUTHOR]

Due to the economic trends around the world and the strong support and guidance of relevant governments, the number of entrepreneurial projects has soared in China. It is necessary to construct a standard assessment system for entrepreneurial projects that is comprehensive and effective. This study extracted six dimensions and 23 criteria for evaluating entrepreneurial projects. This study applies the best and worst methods to obtain the weights of the dimensions and criteria. Then, the Technique for Order Preference by Similarity to an Ideal Solution method was used to evaluate the entrepreneurial projects in an entrepreneurial competition. The results show that team quality, the business model and entrepreneurship ability are the three most important dimensions for evaluating entrepreneurial projects. The improvement of the innovating ability, the training of the team and the value proposition are the three keys to successful implementation of the entrepreneurial projects. [ABSTRACT FROM AUTHOR]

• Proposed hybrid system incorporates a fresh air conditioner with refrigerant system. • Fresh air conditioner has a heat-exchanger network for two-stage energy recovery. • Four independent affecting parameters are included for parametric analysis. • Optimum air-water heat capacity ratio of packed tower is found to be between 0.4–0.6. • Average energy-saving rate of the proposed hybrid system is 44.0%. Energy recovery technologies can effectively improve the energy efficiency of air-conditioning systems and significantly reduce building energy consumption. In this paper, a parametric analysis and energy-saving potential evaluation for a new hybrid air conditioning system (HAC) is carried out theoretically based on developed models. The proposed HAC incorporates into a conventional mechanical vapor compression air conditioning system with an independent fresh air conditioner which is composed of a network of heat exchangers, including a packed bed and three air-water finned coils. Under cold winter climate, in the fresh air conditioner, a packed bed is coupled with a water-air heat exchange coil to form a total energy recovery loop. A run-around sensible energy recovery loop is also integrated in the system to produce a two-stage energy recovery effect. Moreover, a sprayer is installed upstream of the two-stage energy recovery process for fresh air humidification, and a fresh air recirculation duct is equipped for frost-free operation. In the parametric analysis, four independent affecting parameters are included: the air-to-water heat capacity ratio, the indoor temperature, the ambient temperature, and the ratio of recirculation fresh air. The energy-saving potential of the HAC is also evaluated for applications in seven typical cities located in middle-lower Yangtze River region of China over the winter period (December, January and February). The results show that compared with the conventional system with electric humidification, the HAC has an average energy saving rate of 44.0%, and its average power saving per hour is 13.41 W m−2. [ABSTRACT FROM AUTHOR]

In 2018, the Trump Administration claimed for the first time that the United States erred in supporting China's accession to the World Trade Organization because China has failed to fulfill its commitments to dismantle its state-led economy and adopt open-market oriented reforms. Instead, China has maintained a mercantilist state-led economy in which China provides preferential treatment to its state-owned enterprises and supports their exports while it discriminates against U.S. companies in China and creates barriers to U.S. imports. Frustrated with being unable to effect change through dialogue, the United States is now using punitive trade sanctions against China in disregard of the WTO. China has retaliated in kind, igniting a potential global trade war. A review of the background of China's accession to the WTO indicates, however, that China never made any commitments to dismantle the state sector of its economy and is not otherwise legally bound to do so under the WTO. The claim that China agreed to adopt open markets is a myth created by President Bill Clinton due to wishful thinking or political expediency when he sought congressional support for China's accession to the WTO in 2001. Clinton argued that China's WTO entry would lead to the adoption of economic freedoms that in turn would lead to political freedoms and greater protection for human rights. Clinton even dangled the possibility China could shed the shackles of communism and embrace democracy. In response to Clinton's grandiose vision, China remained cautious and made no extravagant promises. China promised only to adopt a hybrid system in which some free markets would operate within an overall state-led economy. Rather than dismantling its state-led economy after its WTO accession, China has incessantly strengthened it. Tightening the state's grip over the economy serves important goals of the Communist Party, including further entrenching its power, whereas loosening its grip would be tantamount to relinquishing power, a prospect that the Party will never accept. This Article argues that the United States must finally reject the Clinton myth and accept that China has no intention of dismantling its state-led economy. Only with this sober realization can the United States deal effectively in the future with China in the WTO, in bilateral trade negotiations outside of the WTO, and beyond. [ABSTRACT FROM AUTHOR]

Regional hybrid energy system (RHES) is an effective way to accommodate clean energy and reduce its uncertainty. It is also an important development direction for energy market reform, playing an important role in the field of energy supply and demand. Based on electricity price, thermal price, and the relationship between load supply and demand, the paper proposes an optimal scheduling model for regional energy systems to promote clean energy consumption. Firstly, the typical structure and system modules of the integrated regional energy system are introduced in detail, and the two subsystem operating models of electricity and heating are given. Secondly, a multi‐objective function that combines the economics and stability of the system is constructed. The model maximizes the economic benefits and minimizes the net load fluctuations on the basis of maximizing the consumption of clean energy. The multi‐objective singularity is realized by fuzzy membership function. The decision‐making risk caused by the uncertainty of clean energy output is analyzed by introducing robust optimization theory. Finally, the effectiveness of the proposed model is verified based on a region in northwestern China. The results show that the proposed multi‐objective model can combine different optimization demands together, maximize the economic characteristics of clean energy while properly controlling risks, and provide reasonable support for decision makers to develop optimal operation plans. [ABSTRACT FROM AUTHOR]

The application of air source heat pumps is mainly restricted by the outdoor ambient temperature, which causes poor application effects in the severe cold region of China. This paper proposes an innovative hybrid energy system of "solar air collector + air source heat pump + energy storage" that is utilized to save energy for ultra-low energy building in severe cold region. The feasibility and performance of this hybrid energy system is studied in Hailar which is located in severe cold region of China. The hybrid energy system is introduced and the dynamic characteristics of the key components of the system are analyzed in combination with the local meteorological conditions. The results indicate that, in Hailar, where the outdoor heating calculation temperature is lower than −30 °C and solar energy resources are not particularly abundant, the peak inlet air temperature of the air source heat pump increases by no less than 10 °C and the coefficient of performance of the system is expected to be higher than 3.0 under extremely low temperature conditions. Warm air from solar air collector can be supplied for heating without ASHP operation if its temperature is higher than 25 °C. These results provide some references for the application of the hybrid energy system in the severe cold region of China. • The hybrid system applied in the severe cold region of China has be proposed. • Performance of the hybrid system has be investigated deeply. • The hybrid energy system can be used for passive ultra-low energy building. • The temperature range of air source heat pump application is broadened. [ABSTRACT FROM AUTHOR]

Battery lifetime is a key factor in the optimal design of hybrid renewable energy systems (HRESs). However, the integration of both battery calendar and cycle lifetimes into HRES design optimization poses challenges in achieving high computational efficiency and ensuring global optimality. In this work, a battery lifetime model considering both calendar and cycle lifetimes is adopted for the simultaneous sizing and scheduling optimization of photovoltaics-wind-battery systems. To reduce computational complexity, the nonlinear term originated from the minimum function, which determines the actual battery lifetime as the earlier-reached one of calendar and cycle lifetimes, is reformulated into a mixed integer linear programming framework. This modified model is then applied to conduct HRES design optimization in China, utilizing climate and load data with 0.5° × 0.5° spatial resolution. High-resolution results not only validate the wide applicability and satisfactory computational efficiency of the proposed model, but also underline the economic importance of incorporating both calendar and cycle lifetimes in system design. It is found that lifecycle costs of stand-alone and grid-connected HRESs could be reduced by 5000k CNY and 22,600k CNY in over 50% of the resource-abundant areas in China, respectively. Moreover, it is discovered that costs of HRESs might apparently increase when local maximum consecutive rainy days (MCRD) exceeds 3, suggesting that MCRD could be a useful indicator to assess system feasibility in diverse locations. This work provides efficient tools and valuable insights that could be generalized worldwide to assist investors and governments in the system siting, evaluation and design processes. • Design optimization of PV-wind-battery system is conducted across China. • A mode efficient model is used to integrate battery calendar and cycle lifetimes. • High-spatial-resolution analysis is performed for both on-grid and off-grid modes. • Incorporating both battery lifetimes greatly reduces cost under certain scenarios. • Maximum consecutive rainy days significantly impacts system design and cost. [ABSTRACT FROM AUTHOR]

Hydropower, an excellent power source for peak shaving, can respond quickly to load changes, which helps to overcome the anti-peak characteristics of wind and solar power. However, complementary operation with wind and solar power changes the operating boundaries of hydropower stations, making the original operating rules no longer applicable. Considering daily peak-shaving demands, this paper proposes a methodology to develop operating rules for a hydro–wind–solar hybrid system (HWSHS). First, a multi-objective and multi-timescale operation model is developed to ensure energy generation and peak-shaving performance simultaneously. Second, the feasible and reasonable region of available energy-based operating rules is analyzed, and three rule forms are employed to explore the optimal operating rules. Last, NSGA-II is utilized to optimize the rule parameters. A decoupling method is proposed to handle the shape constraints of operating rules, and the multi-timescale simulation method for a HWSHS is developed as the fitness function. In the simulation method, a load reconstruction-based load shedding (LRLS) method is introduced to determine the hourly output of each hydropower station. A forebay elevation check method is performed to obtain the hourly forebay elevation and correct the hourly output. The Beipan HWSHS in Guizhou Province, China, is selected as a case study, and the optimal operating rules are determined. The results also show that (1) the standard operating rules with hedging and packing increase peak-shaving performance by an average of 4.31% and 2.03% compared to the standard operating rules and linear operating rules, respectively; (2) the peak-shaving performance can be significantly increased (6.70%) with a slight decrease (0.37%) in the energy generation through changing the seasonal distribution of water and energy of the cascade hydropower stations; (3) the LRLS method, which makes the interday energy distribution more uniform, increases the peak-shaving performance by an average of 9.17% compared to the traditional load shedding method; (4) the energy generation and peak-shaving performance of the HWSHS are affected by the transmission capacity, and it is necessary to increase the transmission capacity by 25% to 35% of the installed capacity of wind and solar power stations. • A methodology is proposed to develop operating rules considering peak-shaving demands. • A multi-objective and multi-timescale operation model is developed. • The feasible and reasonable region of available energy-based operating rules is analyzed. • A multi-timescale simulation method is designed to simulate the operation of a HWSHS. • The methodology significantly improves the peak-shaving performance. [ABSTRACT FROM AUTHOR]

A major distinction between the COVID-19 pandemic and previous pandemics is the significant role of social media platforms in shaping public adherence to non-pharmaceutical interventions and vaccine acceptance. The information propagation and individual emotion communication relevant to public health messages have been promoted in the Chinese Sina Microblog, one of the most popular social platforms in China, through two major interaction mechanisms, "commenting" and "forwarding". Here, we develop a hybrid system of macro information propagation dynamics Susceptible-Commenting-Forwarding-Immune model coupled with the micro emotion influence dynamics Hegselmann-Krause model, termed HK-SCFI coupled system, and reveal the mechanisms of individual emotion infection using the commenting and forwarding data (including time point and content) publicly available on public opinion events in the Chinese Sina Microblog. We demonstrate how our data-driven and model-informed analysis can provide quantitative insights into the co-evolution mechanism of individual emotion during information propagation, describe the emergency of emotion clusters, and predict individual emotion evolution trends. Our study shows that multiple interactive mechanisms can facilitate the propagation of public messages and shape public sentiment through online social networks. Our modeling framework can potentially be a tool for designing effective propagation strategies during public health emergencies. • Establish a dynamic modeling framework to analyze the macro information propagation and micro individual emotion evolution. • Consider two unique interaction mechanisms on the social network. • Introduce an individual character as the inherent factor to illustrate the dynamic emotion interaction. • Effective communication strategies are identified for public health emergencies. [ABSTRACT FROM AUTHOR]

The complementary scheduling of hydropower with wind and photovoltaic (PV) power is an effective way to promote new energy consumption. However, previous studies have disregarded the operational risks of hydropower plants due to their physical constraints when complementing new energy sources. This study proposes a risk control method for a hybrid hydro-PV power system by adding electrochemistry energy storage (EES). A "day ahead–intraday–real-time" three-layer nested model is developed to guide the joint operation of the hydro-PV-EES hybrid system. The complementary flexibility of hydropower and EES is quantified and utilized to minimize unfavorable operating conditions of hydropower units when regulating PV forecast deviations. A case study of China's Longyangxia hydro-PV complementary project shows that after EES is connected to the system: (1) the total power generation of the system is improved 3.04%, and no power curtailment or shortage occurs; (2) the number of startups and shutdowns, and crossing the vibration zone of hydropower units are reduced by 12.87% and 12.17%, thereby improving the safety and operational stability of the hydropower plant; (3) the regulation flexibility supply of the complementary system is considerably improved; and (4) EES achieves flexible and safe control itself, with over 90% of the scheduling periods being in a healthy SOC range. • Quantify the comprehensive regulation flexibility of hydropower and energy storage; • Reduce the operation risk of the hydro-PV complementary system by deploying energy storage; • Propose a complementary operation strategy of hydro-PV- energy storage hybrid power system. [ABSTRACT FROM AUTHOR]

Giving full play to the flexibility of hydropower and integrating more variable renewable energy (VRE) is of great significance for accelerating the transformation of China's power energy system. For middle- to large-sized hydropower units, its irregular vibration zone (VZ) is a major factor affecting its flexibility, because VZs limits the power output and adjustment range. In the existing studies on hydropower unit commitment and flexibility scheduling, VZs only limits the output of hydropower units, while the impact on the flexibility adjustment ability of units is ignored. The hydropower flexibility in day-ahead scheme is overestimated, which increases the risk of system flexibility shortage causing power curtailment and load loss. In this study, a novel day-ahead scheduling model considering the flexibility limited by the VZs and the probability of flexibility shortage is constructed for the day-ahead generation scheme of hydropower-VRE hybrid generation system (HVHGS) to optimize the target load, VRE output and hydropower unit commitments. The impaction of the VZs on hydropower flexibility is firstly modeled by chance constraints and stochastic programming method. Moreover, a data-driven model based on machine learning and an efficient solving approach based on successive linear programming is carry out to describe the uncertainty of VRE output more realistically and ensure the timeliness of optimization scheme, respectively. The proposed model is applied to a real hydropower station in the Hongshui River Basin in China. In 16 representative scenarios, the proposed model can complete the optimization in an acceptable time, with a maximum of 444.57 s. Compared with the traditional interval optimization model, the proposed model effectively improves the flexibility supply capacity of hydropower in the day-ahead scheme. The maximum reduction value of flexibility shortage probability and expectation reach 98.77% and 442.66 MW, respectively. In particular, the flexibility of the model is most obvious under heavy load demand in flood season, and it is almost not at the cost of daily target load adjustment, which provides practical reference for decision makers. • The limitation of vibration zones on flexibility supply of hydropower. • Chance constrains on flexibility shortage probability considering vibration zones. • Machine learning model to describe the uncertainty of variable renewable energy. • Mitigate the risk of insufficient flexibility of day-ahead scheme. [ABSTRACT FROM AUTHOR]

Modern agriculture involves the cooperation of stakeholders in multi-fields where their interaction significantly impacts the planning and operation of rural power systems. However, the traditional planning and operation for rural power systems assumes the power consumption as a given input without considering its unique feature caused by human factors. Particularly in China's rural areas, power consumption will rapidly increase and decrease due to the human-factor-based activity of farmer households' off-farm employment in urban and their home-returning during some important festivals. Therefore, this work proposes a multi-agent decision-making framework to realize the planning and operational optimization of power systems in a human-factor-based rural community. The framework integrates multiple agents' decision-making models including various stakeholders in modern agricultural systems and analyses their interaction. The meteorology-load and meteorology-generation models of power are materialized and embedded in the intensive agriculture and power system agent's decision-making models, which are used by the two agents to estimate the power consumption and photovoltaic (PV) generation, respectively. This work first quantizes the macro choice process of human-factor-based farm and off-farm employment and the numbers innovatively. Further, the farmer behavior for farm employment is simulated by the agent-based modeling system, and the power consumption of the farmer household group is estimated. Based on the overall agents' power consumption in the community, the planning and operation model of the power system is proposed to decide the optimal size and dispatch of the electrical devices. A multi-agent rural community is conducted for the case study to verify the effectiveness of the proposed decision-making framework. The results show that the farmer households who choose off-farm employment account for 66 % of the total households and their power consumption in most of the daytime on weekends is higher than on weekdays. The transportation system agent decides to purchase the electric truck with 5 tons of struck capacity for crop transportation. The power system agent decides to construct a hybrid system of PV, battery energy storage, and a transmission line of less transmission capacity, which can reduce its total system cost. Additionally, this paper finds that the solar radiation obtained by the greenhouse, which is considered the intensive agriculture agent, and its power consumption show opposite variation tendency, and the power consumption of the farmer household group in the Spring Festival is the largest. • A multi-agent decision-making framework of a rural community is proposed. • A meteorology-load and meteorology-generation models are materialized. • A macro choice process of human-factor-based farm/off-farm employment is quantized. • A bottom-up estimation method of power consumption is established by farmer behavior. [ABSTRACT FROM AUTHOR]

Energy systems for flexibility in buildings are hybrid, primarily including rooftop photovoltaics (PV), cooling storage, and battery. Considering their techno-economic patterns, this research establishes an optimization model to determine the optimal technology portfolio and financial advantages of PV-battery-cooling storage systems for commercial buildings in China. The analysis of all cases indicates that cooling storage outperforms batteries in economic benefits, suggesting the prioritization of cooling storage installation. Once the optimal cooling storage rate is exceeded, it is advisable to proceed with batteries. Meanwhile, PV integration significantly enhances the system efficiency and promotes battery utilization. For example, a 40% PV penetration combined with a 0.006 $/(a·kWh e) energy storage investment results in an impressive 27.3% cost reduction in a Beijing mall, while the optimal cooling storage rate decreases from 55% to 40%. Furthermore, the study emphasizes the impact of tariff patterns and electricity demand on the economic feasibility of hybrid energy systems. The museum's substantial annual cooling requirements and nighttime loads make cooling storage favorable, with PV less suitable than the mall and office. Notably, cities like Beijing, Shanghai, Chongqing, and Guangzhou exhibit considerable peak-to-valley tariff differences, yielding higher economic benefits ranging from 23% to 27%. Finally, as battery costs decline and electricity price becomes more volatile, the battery would gradually replace cooling storage, especially when battery cost drops from 150 $/kWh to 70 $/kWh. [Display omitted] • Technology portfolio and cost savings of hybrid energy systems are optimized. • Application potential of PV-battery-cooling storage systems is discussed in China. • Cooling storage is prioritized due to economic performance compared to batteries. • PV integration enhances energy storage efficiency and promotes battery utilization. • Tariff patterns and electricity demand impact economic feasibility of hybrid systems. [ABSTRACT FROM AUTHOR]

A coupled hybrid ensemble square root filter and three-dimensional ensemble-variational (EnSRF-En3DVar) radar data assimilation system, developed for the Weather Research and Forecasting model, was applied to a mesoscale convective system (MCS) that occurred over southeastern China on 5 June 2009. This hybrid system uses the extended control variable method to combine the static and ensemble flow-dependent forecast error covariance. The potential of the hybrid EnSRF-En3DVar system was first explored by comparing the derived results with those obtained using 3DVar and EnSRF approaches alone. Assimilation results showed the hybrid EnSRF-En3DVar system reduces the root mean square innovations for reflectivity and radial velocity, and better represents the pattern of the MCS than either 3DVar or EnSRF. This successful analysis improved quantitative reflectivity and precipitation forecasting skills, and helped forecast the MCS more realistically with regard to location, structure and intensity. Moreover, the root mean square error of the forecast wind, temperature and water vapor mixing ratio were found reduced by the hybrid EnSRF-En3DVar system when compared with the other methods. Diagnoses of the forecast fields showed the hybrid EnSRF-En3DVar system increases low-level cooling and mid-level warming within the convective area. Furthermore, sensitivity experiments testing the ensemble covariance weighting factor effect in the hybrid EnSRF-En3DVar method suggested that a stronger ensemble covariance weighting value led to improved precipitation forecast results. • A new hybrid EnSRF-En3DVar radar data assimilation system is developed and applied to an MCS case. • The improvements of the hybrid approach are found in the forecasting of the MCS comparing with 3DVar and EnSRF. • A stronger ensemble covariance weighting value lead to an improved forecast results. [ABSTRACT FROM AUTHOR]

The overlying rock thickness of a subsea tunnel controls its vertical line. It not only ensures the safety and stability of tunnel construction period and operation period, but also ensures the economy of subsea tunnel. In the current research, few papers give full consideration to the complex indicators of prediction the overlying rock thickness. However, in this study, a hybrid intelligent system was established to predict the overlying rock thickness of a subsea tunnel based on Qingdao Kiaochow Bay Subsea Tunnel, China. The sea depth, basic quality index of rock mass, soft soil layer thickness, permeability coefficient, and construction management level were selected as the main factors influencing the overlying rock thickness. Using the data obtained from project site exploration, objective weight factors were calculated using rough set theory, and subjective weight factors were calculated using the analytic hierarchy process. Furthermore, the combination of weights was obtained for each factor. Finally, the weight of influencing factors was incorporated into the extension model, and the overlying rock thickness of pending section was calculated. The results of overlying rock thickness prediction model are consistent with the actual value, indicating that the model has good engineering applicability and application value. [ABSTRACT FROM AUTHOR]

In this paper, a tramway's system model is established to evaluate its longitudinal dynamics performance, where the model includes multiple masses point connecting together powered by the catenary and a hybrid energy-storage system which consists of a battery pack and ultracapacitor pack. To explore an optimal or appropriate real-time power distribution among these energy sources, a dual fuzzy logic control-based energy management strategy combined with wavelet transform and multi-objective optimization is proposed. The control parameters of the dual fuzzy logic controller are adjusted using a multi-objective particle swarm optimization algorithm while considering the daily operating cost of the tramway. To verify the effectiveness and validity of the proposed model and energy management strategy, its simulation results are further compared and verified with the field experimental results of a real tramway and a real driving cycle in China. • A improved simulation model is presented for a multi-sources hybrid tramway. • A optimal strategy combined with fuzzy logic, wavelet transform and PSO is proposed. • The dual fuzzy logic controller is optimized by multi-objective PSO algorithm. • The strategy shows lower tramway daily operating cost and better energy efficiency. [ABSTRACT FROM AUTHOR]

• An improved deep neural network for capturing the high-dimensional features of wind-solar energy. • A refined model and a two-stage solution for cascade hydropower stations. • Proof of the applicability of only a hydro-wind-solar hybrid system to satisfy power transmission. • Improvement of the quality of generated scenarios helps enhance the hybrid system performance. The high penetration of variable renewable energy sources (RESs) has greatly increased the difficulty in power system scheduling and operation. To fully utilize the complementary characteristics of various RESs, a stochastic optimization model considering the strong regulation capacity of cascade hydropower stations and the uncertainty of wind and photovoltaic (PV) power is presented. Based on the improved generative adversarial networks, the spatial and temporal correlation characteristics between wind farms and PV plants are accurately captured via measured data. Due to the nonlinear features of the hydroelectric plants, linearization methods are adopted to reformulate the original model into a standard mixed integer linear programming (MILP) formulation. Then, the model is solved with a proposed two-stage approach, in which a heuristic algorithm is used to solve the first-stage unit commitment optimization. The cascade hydraulic connection and time delay of the water flow are established in the second stage to exploit the considerably controllable adjustment capability of hydropower generation. A renewable energy base in southwest China is chosen as a detailed case study. The simulation results reveal the potential of the large-scale application of only a hydro-wind-solar hybrid system to satisfy the power transmission demand with the guidance of the coordinated operation strategy, and the performance of the hybrid system can be further enhanced with high-quality scenarios from the proposed deep neural network. [ABSTRACT FROM AUTHOR]

• A novel method for the optimal sizing of the hydro/PV hybrid system is proposed. • A multi-objective model for sizing of the hydro-PV hybrid system is developed. • A method for computing the complementary guarantee rate is presented. • A case study optimizes PV capacity for two large-scale hydro/PV hybrid systems. • The impact of some factors on the complementarity between hydro and PV is analyzed. Solar and wind energy pose a challenge to direct power grid acceptance due to their randomness, intermittency and fluctuation, whereas hydropower with rapid response, good adjustability and stable output has become the most preferred option for complementary energy. In this study, a novel approach to optimal sizing of large-scale hydro-photovoltaic (PV) hybrid systems considering electricity delivery demand and reservoir characteristics has been proposed. We establish a multi-objective mathematical model that minimizes the difference between the daily output process of the hydro-PV hybrid system and the setting-up characteristic load process while maximizing the daily power generation of the hydro-PV hybrid system. The proposed method was applied to a multi-energy complementary base in the upper reaches of the Yellow River in Qinghai Province, China. The results show that the optimal PV capacity for a hydro-PV hybrid system and the complementary guarantee rate are closely related to electricity delivery demand and reservoir characteristics. It was observed that at the complementary guarantee rate of 0.7, the optimal PV capacities of the Yangqu-PV hybrid system were 402 and 425 MW under three- and five-segment line modes, respectively, with the corresponding optimal PV capacities of the Banduo-PV hybrid system at 129 and 154 MW under three- and five-segment line modes, respectively. Additionally, the Yangqu-PV hybrid system meets bimodal and unimodal load shaving well; however, the Banduo-PV hybrid system only satisfies unimodal load shaving well. Finally, simulation results indicate that upstream reservoir regulation, hydropower expansion and regulated storage capacity expansion benefit the complementarity between hydro and PV. The highlighted results verify the feasibility of the proposed method. Therefore, the proposed method provides technical support and reference for planning and constructing PV power plants and can be used to implement other hybrid systems in the future. [ABSTRACT FROM AUTHOR]

The Junggar Basin of NW China is representative in containing oil and gas seeps worldwide as there are a wide variety of oil and gas seeps over a large area. However, the genesis of these seeps remains poorly known, limiting the understanding of their implications for petroluem geology and hydrocarbon exploration. Here, we investigate 26 samples of oil and gas seeps from nine outcrops within five areas along the margins of the Junggar Basin to determine the geochemical characteristics of the hydrocarbons, constrain their genesis, and discuss future exploration strategies. Results indicate one type of gas seeps and five types of oil seeps. The gas seeps are derived from low-maturity Jurassic source rocks and occur in the Wusu and Dushanzi areas in the western segment of the southern basin. Type 1 oil seeps, sourced from lower Permian rocks (P1f), occur on the northwestern margin. Type 2 oil seeps, derived from middle Permian source rocks (P2l/P2p), occur on the eastern segment of the southern margin and eastern margin of the Junggar Basin. Type 3 oil seeps, with Jurassic source rocks, occur in the Qigu area in the middle segment of the southern basin. Type 4 oil seeps, with Cretaceous source rocks, occur in the Anjihai and Huoerguosi areas within the middle segment of the southern basin. Type 5 oil seeps mainly have Paleogene source rocks with a minor contribution from Jurassic rocks and occur in the Wusu and Dushanzi areas in the western segment of the southern basin with the single-type gas seeps. These results indicate the presence of lacustrine hybrid petroleum systems within the Junggar Basin with complex oil and gas sources and migration-accumulation. Six potential areas along the basin margin were proposed for exploration in the future. [ABSTRACT FROM AUTHOR]

Highlights • The small signal dynamic model for a hybrid 3-terminal HVDC system is developed. • This paper identifies the low-damped oscillatory modes of the hybrid system. • This paper investigates the impact of power-type controllers on the system. • The impact of AC system strength on system stability is investigated. • The findings are useful for systematic design of the HVDC system. Abstract The Hybrid Multi-Terminal High Voltage Direct Current (H-MTDC) transmission system can take advantages of Line-Commutated Converter (LCC) technology to reduce capital cost and Modular Multilevel Converter (MMC) technology to eliminate commutation failure (CF) issues, and recently attracts much attention in academic research and practical engineering. Based on the scheme of Wudongde H-MTDC project, which is under construction in China, this paper develops a small-signal dynamic model of the hybrid 3-terminal HVDC system, adopting an LCC station at rectifier and two MMC stations at inverter. Then, the small-signal model is validated by comparing its time-domain responses with the detailed electromagnetic transient (EMT) simulation results obtained from PSCAD/EMTDC. Based on eigen-analysis and participation factor methods, this paper identifies the oscillatory modes of the overall hybrid system. From the revealed oscillatory modes, it indicates that DC-side active power relevant state variables and MMC internal harmonics have major contributions to low-damped modes which may result in instability of the system. Then, the effects of power-type controllers, i.e., constant DC current controller of LCC station, DC-side voltage controller of MMC station and active power controller of MMC station, and circulating current suppressing controllers (CCSC) of MMC stations on the stability of the hybrid system are investigated. Finally, the effects of AC system strength on the stability of the hybrid system are analyzed. The results show that smaller proportional gains of constant DC current controller of LCC and DC-side voltage controller of MMC can enhance the system small-signal stability. And the active power controller gain of MMC station has slight influences on the system stability. Moreover, the CCSC gains are required to be properly selected based on the system setup to prevent from the possible internal harmonic instability of MMC stations. [ABSTRACT FROM AUTHOR]

The Mutsu-Isuzu cytoplasmic male sterility (MI CMS) system is one of the three-line hybrid systems used in China. As we know, the hybrid system is tightly associated with the yield variation in F1 heterosis, while the restorer gene for the Ml CMS (Rfm) has not been finely mapped for further application in marker-assisted selection (MAS). In this study, the sets of near-isogenic lines (NILs) of Rfm in two different genetic backgrounds were hybridized with the genome-wide 60 K single-nucleotide polymorphism (SNP) chip of Brassica for screening the possible associated genomic region of Rfm. Through screening genotypes with SNP loci and sequencing the candidate loci, one 2.5 Mb physical region (covering three scaffolds) on chrA09 w'as identified as the candidate for the Rfm region. Then, the SSR markers for the target scaffolds were used to delect the recombination in an F2 population and narrowed the Rfm gene within the genetic distance of 0.52 cM, equivalent to a 350 kb physical segment. Moreover, the markers w'ere tested to improve new elite restoration lines and to assess the percentage of hybrid seeds. Our results could potentially accelerate the map-based cloning of the Rfm gene to benefit rapeseed breeding. [ABSTRACT FROM AUTHOR]

Abstract A novel concept of energy harvesting method (PV-RC) based on the conventional photovoltaic (PV) panel, combining diurnal PV conversion and nocturnal radiative cooling (RC) method, was developed to generate electricity and obtain cooling energy. A PV-RC hybrid system was also designed, manufactured, and spectral characterized, which exhibit high solar absorption in PV conversion band (0.3–1.1 μm) and has strong thermal emission within thermal radiation band (4–25 μm). Experimental studies of the hybrid system were carried out in Hefei (117° E, 32° N), China. The measured results demonstrate that the hybrid system has an average electricity output of 75.7 W m−2 with an average electrical efficiency of 12.4% for diurnal PV conversion and exhibits an equilibrium temperature reduction of 12.7 °C below ambient temperature for nocturnal RC process. Parametric studies were also conducted by a validated simulation model, which discuss the effects of different meteorological parameters on the performance of the system. The simulated results imply that dry regions are more suitable for nocturnal RC mechanism. Highlights • PV panel based photovoltaic and radiative cooling (PV-RC) system was proposed. • A PV-RC hybrid system was designed, manufactured, and spectral characterized. • An average electricity output of 75.7 W m−2 was obtained at daytime PV mode. • An average temperature reduction of 12.7 °C was obtained at nighttime RC mode. • Thermal analysis was conducted by validated mathematical model. [ABSTRACT FROM AUTHOR]

• Refined model for cascade hydropower stations and optimal reservoir operation strategy. • Vine copula for capturing the spatial and temporal characteristics of wind-solar energy. • Demonstrated potential for a hydro-wind-solar hybrid system to ensure stable power export. • Case study that optimizes the installed capacity of the integrated wind and PV plants. The high proportional integration of variable renewable energy sources (RESs) has greatly challenged traditional approaches to the safe and stable operation of power systems. Considering the complementary characteristics of various RESs, an optimization model is proposed in this study for cascade hydropower stations coupled with renewable-energy-based power generation methods such as wind and photovoltaics (PV). Building on the autoregressive moving average (ARMA) model and improved vine-copula theory, a joint distribution model for wind and PV power is built with measured data to capture the spatial and temporal correlations between wind and solar plants, and sufficiently representative scenarios for renewable energy generation are explored. Due to nonlinearities in the forebay elevation vs. reservoir volume, tailwater elevation vs. water flow, and head-sensitive power generation in hydropower stations, several linearization approaches are used to reformulate the optimization model into a more tractable form. The hydraulic relationship and time delay of water flow between cascade reservoirs are established to make full use of the controllable complementarity of hydropower generation. Optimized coefficients of coordinated operations in different seasons are obtained by a heuristic algorithm for cascade reservoirs. A detailed case study is undertaken in a basin with wind farms and solar arrays in Southwest China, and the simulation results demonstrate the potential of a large-scale hydro–wind–solar hybrid system to meet export power transmission demands. Finally, the optimal capacity of wind and PV plants is determined to inform the future planning and construction of actual systems. [ABSTRACT FROM AUTHOR]