Persistent energy–time entanglement covering multiple resonances of an on-chip biphoton frequency comb

We investigate the time-frequency signatures of an on-chip biphoton frequency comb (BFC) generated from a silicon nitride microring resonator. Using a Franson interferometer, we examine the multifrequency nature of the photon pair source in a time entanglement measurement scheme; having multiple frequency modes from the BFC results in a modulation of the interference pattern. This measurement together with a Schmidt mode decomposition shows that the generated continuous variable energy–time entangled state spans multiple pair-wise modes. Additionally, we demonstrate nonlocal dispersion cancellation, a foundational concept in time–energy entanglement, suggesting the potential of the chip-scale BFC for large-alphabet quantum key distribution

Assessing Grain Productivity Coupled with Farmers’ Behaviors Based on the Agro-Ecological Zones (AEZ) Model

This study presents a method that dynamically embeds constraints of farmers’ management and input levels to improve a traditional agro-ecological zones (AEZ) model to solve the problem of overestimation of grain production capacity. The proposed method is applied to Yuanjiang county in central China to evaluate the grain productivity of farmland and analyze its spatial distribution characteristics. Our results indicated that (1) The feasibility of the AEZ method coupled with farmers’ behavior had been verified, and the revised model can better improve the accuracy of the evaluation results. (2) Low-value areas of grain production potential are mainly distributed in the central region, high-value areas are mainly distributed in the southwest and northeast regions, and the spatial differentiation characteristics of production potential and total production capacity are the same. (3) The total grain productivity is 935,800 tons, and the total yield gap is 470,100 tons, which is 1.01 times the actual yield, indicating a large potential to increase grain production under the current technicality. The main contribution of this study is to propose a method to dynamically embed farmers’ behavioral factors into the traditional AEZ model, and apply this method to the actual farmland productivity evaluation in small-scale areas, which improves the reliability of the actual regional productivity evaluation results

Assessing Grain Productivity Coupled with Farmers’ Behaviors Based on the Agro-Ecological Zones (AEZ) Model

This study presents a method that dynamically embeds constraints of farmers’ management and input levels to improve a traditional agro-ecological zones (AEZ) model to solve the problem of overestimation of grain production capacity. The proposed method is applied to Yuanjiang county in central China to evaluate the grain productivity of farmland and analyze its spatial distribution characteristics. Our results indicated that (1) The feasibility of the AEZ method coupled with farmers’ behavior had been verified, and the revised model can better improve the accuracy of the evaluation results. (2) Low-value areas of grain production potential are mainly distributed in the central region, high-value areas are mainly distributed in the southwest and northeast regions, and the spatial differentiation characteristics of production potential and total production capacity are the same. (3) The total grain productivity is 935,800 tons, and the total yield gap is 470,100 tons, which is 1.01 times the actual yield, indicating a large potential to increase grain production under the current technicality. The main contribution of this study is to propose a method to dynamically embed farmers’ behavioral factors into the traditional AEZ model, and apply this method to the actual farmland productivity evaluation in small-scale areas, which improves the reliability of the actual regional productivity evaluation results

Regional Differences in Ecological Compensation for Cultivated Land Protection: An Analysis of Chengdu, Sichuan Province, China

Exploring the elements that affect farmers’ willingness to protect cultivated land is the key to improving the ecological compensation mechanism for cultivated land protection. The purpose of this study was to analyze regional differences in ecological compensation for cultivated land protection, and to explore the influence of different external environments on farmers’ willingness to engage in cultivated land protection. Based on the Profitable Spatial Boundary Analysis theory (PSBA), GIS spatial analysis technology was used to analyze regional space differences and assess ecological compensation for urban and rural cultivated land protection at the micro scale. The results show that the willingness of farmers to participate in cultivated land protection is affected by the external environment and the ecological compensation offered. The trend of the comprehensive benefit of cultivated land protection ecological compensation (B) is “Λ” from the first layer to the third layer. The B value of the urban–rural junction area is the highest value. This shows that the external environment is favorable for ecological compensation in this area, which has a positive effect on farmers’ willingness to protect cultivated land. B < 0 in the first and third layer, which has a depressant effect on farmers’ willingness to protect cultivated land. The study results contribute to the understanding of the impact of regional differences in the external environmental on ecological compensation and farmers’ willingness to engage in cultivated land protection

Classification of Complete Regular Minimal Surfaces in ℝ<i>ⁿ</i> with Total Curvature −6<i>π</i>

In this paper, we classify the complete regular orientable minimal surfaces in Rn with total curvature −6π and give a method to construct a series of complete non-holomorphic minimal surfaces with total curvature −6π. Specially, we give a simplified classification in another method if the surfaces lie in R4

A Framework of Payment for Ecosystem Services to Protect Cropland: A Case Study of the Yangtze River Delta in China

Due to large land demand and insufficient economic incentives, stakeholders have little motivation to protect cropland during rapid urbanization. The considerable loss of cropland poses a serious threat to food security and ecological sustainability. This research proposes a framework of payment for ecosystem services (PES) to reconcile the large land demand and the need for cropland protection during economic development by identifying whom to compensate, what to pay, how much to pay, the mechanisms for payment, and verification of service delivery. Using the Yangtze River Delta as an example, the features of the PES based on supply-demand analysis, compensation quality and value standards, and payment regulation are demonstrated. The results show the effectiveness of this PES framework for handling the externality of environmental protection compared to traditional regulatory approaches. The framework will also aid in the protection of cropland by coordinating the benefits of stakeholders

Study on prediction and optimization of gas–solid erosion on S-Zorb reactor distribution plate

Adsorption desulfurization of catalytic gasoline (S Zorb) is an important desulfurization measure that is performed to meet the environmental protection requirements before the final product oil is sold in the market. The desulfurization reactor is a gas–solid two-phase flow environment composed of high-temperature and high-pressure hydrogen-oil mixed gas and sorbent particles; erosion prominently occurs on the reactor distribution plate. This study selects the typical gas–solid two-phase flow conditions and defines the erosion mechanism of the gas–solid two-phase flow environment for the plastic material of E347. Moreover, an S Zorb desulfurization reactor model is constructed, the CFD-DEM model is adopted to predict the wall erosion characteristics in a gas–solid two-phase flow environment, typical erosion laws are obtained via calculations. The erosion laws under the influence of variable parameters are studied based on the orthogonal test, the orthogonal test results show the best parameter combination, the parameter combination yields the maximum erosion rate and high erosion area that are 29.9% and 17.3%, respectively, lower than the existing values. Moreover, an optimum scheme of the inner structure parameters of the reactor is determined for reducing erosion rate and area

Coupling Ecological Security Pattern Establishment and Construction Land Expansion Simulation for Urban Growth Boundary Delineation: Framework and Application

Reasonable delineation of the urban growth boundary (UGB) plays a vital role in guiding orderly urban space growth and ensuring urban environmental health. Existing methodologies for UGB delineation have failed to address the significance of ecological security. Therefore, this study presents a framework that couples ecological security pattern (ESP) establishment and construction land expansion (CLE) simulation to delineate the UGB. The proposed framework is applied to the Nanchang Metropolitan Area (NCMA) in southeastern China. First, we established the regional ESP of the NCMA in 2018 based on an improved minimum cumulative resistance model. The areas of low-, medium-, and high-level ESP were 1050.75, 736.42, and 720.59 km2, respectively. Second, we implemented a multi-scenario simulation of CLE in the NCMA in 2025 based on a cellular automata–Markov model. A natural development scenario was superior to urban growth and ecological protection scenarios for social, economic, and ecological development at the regional scale. Accordingly, we delineated the UGB of the NCMA in 2025 with a scale of 687.87 km2, based on dynamic adjustment using the results of ESP establishment and CLE simulation in the natural development scenario. The rationality and scientificity of the proposed framework were verified by comparing the scale and layout of the delineated UGB with the regional planning of Nanchang City. The framework incorporating dynamic adjustment with ESP establishment and multi-scenario CLE simulation provides a useful tool for the delineation of the UGB in similar urbanized cities. Its application is conducive to achieving a win–win outcome of regional ecological security and urban development

Coupling Ecological Security Pattern Establishment and Construction Land Expansion Simulation for Urban Growth Boundary Delineation: Framework and Application

Reasonable delineation of the urban growth boundary (UGB) plays a vital role in guiding orderly urban space growth and ensuring urban environmental health. Existing methodologies for UGB delineation have failed to address the significance of ecological security. Therefore, this study presents a framework that couples ecological security pattern (ESP) establishment and construction land expansion (CLE) simulation to delineate the UGB. The proposed framework is applied to the Nanchang Metropolitan Area (NCMA) in southeastern China. First, we established the regional ESP of the NCMA in 2018 based on an improved minimum cumulative resistance model. The areas of low-, medium-, and high-level ESP were 1050.75, 736.42, and 720.59 km2, respectively. Second, we implemented a multi-scenario simulation of CLE in the NCMA in 2025 based on a cellular automata&ndash;Markov model. A natural development scenario was superior to urban growth and ecological protection scenarios for social, economic, and ecological development at the regional scale. Accordingly, we delineated the UGB of the NCMA in 2025 with a scale of 687.87 km2, based on dynamic adjustment using the results of ESP establishment and CLE simulation in the natural development scenario. The rationality and scientificity of the proposed framework were verified by comparing the scale and layout of the delineated UGB with the regional planning of Nanchang City. The framework incorporating dynamic adjustment with ESP establishment and multi-scenario CLE simulation provides a useful tool for the delineation of the UGB in similar urbanized cities. Its application is conducive to achieving a win&ndash;win outcome of regional ecological security and urban development