Assessment of the spatial and temporal variations of water quality for agricultural lands with crop rotation in China by using a HYPE model

Many water quality models have been successfully used worldwide to predict nutrient losses from anthropogenically impacted catchments, but hydrological and nutrient simulations with little data are difficult considering the transfer of model parameters and complication of model calibration and validation. This study aims (i) to assess the performance capabilities of a new and relatively more advantageous model-hydrological predictions for the environment (HYPE) to simulate stream flow and nutrient load in ungauged agricultural areas by using a multi-site and multi-objective parameter calibration method and (ii) to investigate the temporal and spatial variations of total nitrogen (TN) and total phosphorous (TP) concentrations and loads with crop rotation using the model for the first time. A parameter estimation tool (PEST) was used to calibrate parameters, which shows that the parameters related to the effective soil porosity were most sensitive to hydrological modeling. N balance was largely controlled by soil denitrification processes, whereas P balance was influenced by the sedimentation rate and production/decay of P in rivers and lakes. The model reproduced the temporal and spatial variations of discharge and TN/TP relatively well in both calibration (2006–2008) and validation (2009–2010) periods. The lowest NSEs (Nash-Suttclife Efficiency) of discharge, daily TN load, and daily TP load were 0.74, 0.51, and 0.54, respectively. The seasonal variations of daily TN concentrations in the entire simulation period were insufficient, indicated that crop rotation changed the timing and amount of N output. Monthly TN and TP simulation yields revealed that nutrient outputs were abundant in summer in terms of the corresponding discharge. The area-weighted TN and TP load annual yields in five years showed that nutrient loads were extremely high along Hong and Ru rivers, especially in agricultural lands

Intraday multi-objective hierarchical coordinated operation of a multi-energy system

An intraday, multi-objective, hierarchical and coordinated operation scheduling method for a multi-energy system (MES), which uses 15-min and 5-min scheduling intervals for different energy subsystems, is proposed. According to the characteristics of MES and the response time of energy conversion equipment, energy subsystems are dispatched on different dispatch intervals instead of unified dispatch intervals to dispatch energy subsystems. In a case study, the prediction error rate for a load is 5% and 2% when the dispatch interval is 15 min and 5 min, respectively; the prediction error rates for wind and solar energy output are 10% and 5%, respectively. Dispatching different subsystems with different intervals according to their characteristics reduces the impact of source and load uncertainties, which improves energy management. Multi-energy power dispatch considers exergy efficiency and the operation cost to improve the utilization energy efficiency. The Tchebycheff method, which considers the fuzzy entropy weight, is employed to balance the objectives between highest exergy efficiency and lowest operation cost. Numerical studies demonstrate that the operation cost of a multi-objective system is ¥500.8877 higher than that of a system with the objective of lowest operation cost. The exergy efficiency is increased by 3.94%, and the operation cost, which is reduced by ¥1706.9606, is 2.13% lower than that for the objective of highest exergy efficiency. Thus, the proposed method can balance the objectives between highest exergy efficiency and lowest operation cost. These findings provide a multi-dimensional dispatch scheme for dispatchers and highlight the development potential of an MES

Coordinated configuration strategy of multi-energy systems based on capacity-energy-information sharing

Multi-energy systems (MESs) integrate multiple energy vectors and contribute to energy efficient utilization, which have received considerable attention in the energy research field. However, regarding a MES with multi communities, the coordination among the communities has not been fully considered in its planning and configuration. Therefore, this paper proposes a coordinated configuration strategy for MES planning based on capacity-energy-information sharing. First, analysing the capacity, energy and information sharing mechanisms among communities, an improved energy hub (EH) model and hierarchical planning framework for MES is built. Moreover, a bilevel configuration model that coordinates the planning and operation stages is developed to design a MES, which is guided by the information sharing of communities. While the upper level model makes the optimal quantity and capacity configuration plan of communities with consideration of capacity sharing, the lower level model optimizes the best operation economy considering energy interactions in MES scheduling. Finally, a case study is carried out and simulation results show that, compared with the planning approaches in the reference cases, the proposed strategy contributes to a decrease in the MES planning costs and exhibits better performances in jointly considering the planning economy, robustness, carbon emissions and user benefits

Atomistic simulations of dislocation mobility in refractory high-entropy alloys and the effect of chemical short-range order.

Refractory high-entropy alloys (RHEAs) are designed for high elevated-temperature strength, with both edge and screw dislocations playing an important role for plastic deformation. However, they can also display a significant energetic driving force for chemical short-range ordering (SRO). Here, we investigate mechanisms underlying the mobilities of screw and edge dislocations in the body-centered cubic MoNbTaW RHEA over a wide temperature range using extensive molecular dynamics simulations based on a highly-accurate machine-learning interatomic potential. Further, we specifically evaluate how these mechanisms are affected by the presence of SRO. The mobility of edge dislocations is found to be enhanced by the presence of SRO, whereas the rate of double-kink nucleation in the motion of screw dislocations is reduced, although this influence of SRO appears to be attenuated at increasing temperature. Independent of the presence of SRO, a cross-slip locking mechanism is observed for the motion of screws, which provides for extra strengthening for refractory high-entropy alloy system

Anodic oxidation triggered divergent 1,2- and 1,4-group transfer reactions of β-hydroxycarboxylic acids enabled by electrochemical regulation.

We report a set of electrochemically regulated protocols for the divergent synthesis of ketones and β-keto esters from the same β-hydroxycarboxylic acid starting materials. Enabled by electrochemical control, the anodic oxidation of carboxylic acids proceeded in either a one-electron or a two-electron pathway, leading to a 1,4-aryl transfer or a semipinacol-type 1,2-group transfer product with excellent chemoselectivity. The 1,4-aryl transfer represents an unprecedented example of carbon-to-oxygen group transfer proceeding via a radical mechanism. In contrast to previously reported radical group transfer reactions, this 1,4-group transfer process features the migration of electron-rich aryl substituents. Furthermore, with these chemoselective electrochemical oxidation protocols, a range of ketones and β-keto esters including those possessing a challenging-to-access medium-sized ring could be synthesized in excellent yields

Atomistic simulations of dislocation mobility in refractory high-entropy alloys and the effect of chemical short-range order.

Refractory high-entropy alloys (RHEAs) are designed for high elevated-temperature strength, with both edge and screw dislocations playing an important role for plastic deformation. However, they can also display a significant energetic driving force for chemical short-range ordering (SRO). Here, we investigate mechanisms underlying the mobilities of screw and edge dislocations in the body-centered cubic MoNbTaW RHEA over a wide temperature range using extensive molecular dynamics simulations based on a highly-accurate machine-learning interatomic potential. Further, we specifically evaluate how these mechanisms are affected by the presence of SRO. The mobility of edge dislocations is found to be enhanced by the presence of SRO, whereas the rate of double-kink nucleation in the motion of screw dislocations is reduced, although this influence of SRO appears to be attenuated at increasing temperature. Independent of the presence of SRO, a cross-slip locking mechanism is observed for the motion of screws, which provides for extra strengthening for refractory high-entropy alloy system