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Micro-grid can be used as a supplement to power supply of large power grids. Combined with smart park, users can easily manage the micro-grid. In the tourist scenic area, the local distributed new energy is mainly used to provide energy for the system. The micro-grid control system as the core of the system controls the optimal operation of the entire smart park. In order to ensure the efficient operation of the entire system, the energy management system is needed for smart control and automatic scheduling. In the grid-connected mode, the main-grid complements the system energy and charges the park energy storage device. In the island mode, the distributed energy is fully used to provide energy for the smart park system. The energy power fluctuates greatly, and the energy management system needs to schedule the micro-grid energy, energy storage system, electric vehicle load and so on, and power quality needs to be monitored. Use of micro-grid control system in the smart parking deploying photovoltaic power generation, wind power generation, charging and exchanging devices and other devices, real-time monitoring of the park of cars, charging cars automatically complete charging, automatic processing of visitor cars into and out of smart park, and improve work efficiency.

The majority of a coal mine's goaf is semi-closed complex porous medium space, which is a critical place for coal spontaneous combustion disasters. To investigate the flow diffusion pattern of inorganic compounds in fractured coal in the goaf, as well as the capacity to put out coal fires. It examine the viscosity properties of an inorganic material slurry as a function of water/material ratio and time. By building a three-dimensional grouting test platform in the lab, simulating the broken coal body with sand and gravel, designing orthogonal tests to run multiple groups of grouting tests, and analyzing the effects of factors besides grouting pressure, water/material ratio, and air space ratio on the slurry diffusion radius. The effect of grouting pressure on the pattern of slurry diffusion radius of inorganic material and the water/material ratio under the action of grouting pressure is studied. The test of inorganic materials to extinguish coal pile fire is done, and the fire extinguishing and cooling ability is assessed in comparison to mud of the same grade, based on a prior research of inorganic materials to suppress CO formation in coal oxidation warming. According on the findings, the three-dimensional grouting test platform can pass the grouting test of loose sand and gravel bodies at various grouting pressures. The effects of grouting pressure, water/material ratio, and air space ratio on slurry dispersion are discovered to be multivariate power function relationships rather than linear correlations. The related slurry diffusion radius equation is established, and the variables impacting the parameters of the slurry diffusion range are evaluated, with the grouting pressure and water/material ratio having a substantial impact on slurry diffusion. Inorganic materials, as opposed to mud, require less time to extinguish coal pile fires and are less prone to scatter. It can form an oxygen barrier through continually covering the surface of coal. The study's findings might give a solid foundation for the avoidance of slurry and fire suppression of inorganic materials in the goaf. [ABSTRACT FROM AUTHOR]

In the field of substation operation and maintenance, real-time detection and precise segmentation of tools play an important role in maintaining the safe operation of the power grid and guiding operators to work safely. To improve the accuracy and real-time performance of semantic segmentation of substation operation and maintenance tools, we have proposed an improved, light-weight, real-time, semantic segmentation network based on an efficient image cascade network architecture (ICNet). The network uses multiscale branches and cascaded feature fusion units to extract rich multilevel features. We designed a semantic segmentation and purification module to deal with redundant and conflicting information in multiscale feature fusion. A lightweight backbone network was used in the feature extraction stage at different resolutions, and a recursive gated convolution was used in the upsampling stage to achieve high-order spatial interactions, thereby improving segmentation accuracy. Due to the lack of a substation tool semantic segmentation data set, we constructed one. Training and testing on the data set showed that the proposed model improved the accuracy of tool detection while ensuring real-time performance. Compared with the currently popular semantic segmentation network, it had better performance in real-time and accuracy, and provided a new semantic segmentation method for embedded platforms. [ABSTRACT FROM AUTHOR]

Three‐dimensional ordered macroporous (3DOM) materials have good properties in the mass transfer and diffusion. Herein, a novel Z‐scheme 3DOM‐ZrO2/Cd0.5Zn0.5S (Zr3D/CZS) heterojunction catalyst was prepared and applied to photocatalytic water splitting for hydrogen production. The results show that the three‐dimensional macroporous zirconia is conducive to the transport of photogenerated charges, and the optimal catalyst 2Zr3D/CZS achieves the highest hydrogen production rate of 83.12 mmol g−1 h−1 under the full spectrum illumination, which is 213 and 2 times higher than that of pure ZrO2 (0.39 mmol g−1 h−1) and CZS (40.86 mmol g−1 h−1), respectively. Under 450 nm light irradiation, the apparent quantum efficient is up to 44 %. In addition, the catalyst also showed good stability. The possible charge transfer mechanism was proposed under the full spectrum and visible light, respectively. This work provides an efficient strategy for design and synthesis of high active ZrO2 based photocatlysts for hydrogen production. [ABSTRACT FROM AUTHOR]

The effects of various energy conservation and carbon reduction (ECCR) strategies can differ significantly despite equal investment. Given limited amount of capital expenditure, managers and planners of industrial parks must carefully select from different ECCR strategies and implementation technologies to maximize investment returns. This study establishes mathematical models for four ECCR strategies: forestry carbon sequestration (FCS), carbon capture and utilization (CCU), waste heat recovery (WHR), and photovoltaic (PV). A universal ECCR planning optimization model is constructed to maximize annual economic benefits or carbon emission reduction. Using an industrial park in southern China as a case study, genetic algorithms are utilized to solve the model and validate its feasibility. The study analyzes three key parameters: capital expenditure caps, carbon trading price in the Emission Trading Scheme, and transportation distance of captured CO2 products for sensitivity. The results demonstrate considerable economic benefits of the CCU strategy when demand matches appropriately. However, in cases with limited capital expenditure, implementing small-scale FCS strategies in industrial parks is not advisable from both an economic and environmental perspective. [ABSTRACT FROM AUTHOR]

From the end of May to the first ten days of June in 2020, a 12 day heavy rain process occurred in Guangxi. Due to the extreme complexity of its formation, it is necessary to analysis deeply and reveal its characteristics and causes. Based on hourly EC ERA5 0.25° x 0.25° reanalysis and real data, a multiscale comprehensive analysis of the process is carried out. The results show that:(1) This process has the characteristics of long duration of heavy rainfall, wide range, strong intensity, large accumulated rainfall, breaking the historical record of 24 h rainfall in many places and particularly serious disaster. (2) The process occurs under the circulation background of favorable configuration of mid-and-high-latitudes circulation, subtropical high, Bay of Bengal trough, low-level jet and South Asia high. There is no stable confrontation between the South Asian high transition layer and the subtropical high. there is a Transition from the meridional circulation to zonal circulation in mid-and-high-latitudes. The influence of cold air on South China is fluctuating, it causes alternating effects of cold front, stationary front and warm-sector. Thus, the local, regional and provincial rainstorms occur alternately, which is obviously different from the previous continuous rainstorms. (3) The atmosphere accumulates large energy, and huge energy is accumulated before the rainstorm in the fronts and warm-sector. Energy accumulation and effective release are positively correlated with the maximum hourly rainfall. The high temperature and humidity of the lower atmosphere and the deep wet layer of the whole atmosphere and the smaller CIN and lower TCL_P are conducive to energy accumulation and convection triggering. Warm sector and static Front Rainstorm have easier environmental conditions for triggering. The extreme convergence of energy, power and water vapor leads to the extreme rainfall. (4) The frontal rainstorm is triggered by the surface mesoscale frontal area, shear line and terrain. The combination of systems and the enhancement of low-level environmental wind field organize the development of convection. The warm-sector rainstorm is triggered by the cyclonic shear on the left side of the boundary layer jet axis, the convergence of low-level jet outlet and topographic uplift. The pulsation of jet stream enhances the development of convection. (5) The frontal rainstorm is a mobile cloud belt, and the warm sector rainstorm is a less mobile cloud cluster. The lower the cloud top brightness temperature, the greater the maximum hourly rainfall. The cloud top brightness temperature lower than 200 K can be used as the criterion for the maximum hourly rainfall greater than 50 mm/h. The maximum hourly rainfall occurs after the minimum cloud top brightness temperature reaches the minimum value. The heavy rainfall begins with the maximum radar RCS ≥ 45 dBZ and lasts for the maximum radar RCS ≥ 50 dBZ. The front echo is cold cloud echo with high centroid, and the warm-sector echo is warm cloud echo with low centroid. (6) Topography plays an important role in triggering and maintaining rainstorm, and it is more obvious for warm-sector rainstorm.(7) There are differences between the observation and reanalysis data in the penetration analysis of weak cold air, and the former is easier to capture the convective trigger. [ABSTRACT FROM AUTHOR]

Coal is the main energy source in China, and spontaneous combustion of coal is one of the main disasters in coal mines. Fully mechanized caving top coal mining technology is widely used in coal mines. Under the comprehensive action of multiple factors, gas generated by coal oxidation and low oxygen gas in goaf is easy to rush to working face, resulting in lower oxygen concentration in upper corner and exceeding harmful gas concentration. It seriously threatens the health of underground workers and the normal operation of production. If the oxygen concentration in the upper corner is changed, it is bound to cause the change of the oxygen concentration in the goaf and aggravate the threat of spontaneous combustion of coal in the goaf. In order to solve the double threat of low oxygen in upper corner and coal spontaneous combustion in goaf, based on Coulomb model, this paper uses command flow to conduct numerical simulation tests on the failure law of overlying strata, and obtains the influence of mining of the lower 1 coal seam and the lower 5 coal seam on the overlying strata subsidence and surface penetration. Based on the comprehensive consideration of atmospheric pressure, ore pressure activity, external air leakage and other factors, the mixed model of the source and emission of low oxygen gas in goaf was established, and the formation mechanism of low oxygen problem in the corner of return air of working face was defined. The use of pressure air belt to deal with low oxygen in return air corner is proposed creatively. The comprehensive fire prevention measures such as corner plugging, nitrogen injection and grouting are used to inhibit the oxidation of the left coal and the influx of low oxygen gas to the corner in the goaf, so as to achieve the goal of collaborative prevention and control of low oxygen in the corner of return air and coal spontaneous combustion. The research results have important reference significance for the mine with the risk of spontaneous combustion or the problem of low oxygen in the return air corner. [ABSTRACT FROM AUTHOR]

Background: Pancreatic neuroendocrine tumors (PNETs) are one of the most common endocrine tumors, and liver metastasis (LMs) are the most common location of metastasis from PNETS; However, there is no valid nomogram to predict the diagnosis and prognosis of liver metastasis (LMs) from PNETs. Therefore, we aimed to develop a valid predictive model to aid physicians in making better clinical decisions. Methods: We screened patients in the Surveillance, Epidemiology, and End Results (SEER) database from 2010–2016. Feature selection was performed by machine learning algorithms and then models were constructed. Two nomograms were constructed based on the feature selection algorithm to predict the prognosis and risk of LMs from PNETs. We then used the area under the curve (AUC), receiver operating characteristic (ROC) curve, calibration plot and consistency index (C-index) to evaluate the discrimination and accuracy of the nomograms. Kaplan-Meier (K-M) survival curves and decision curve analysis (DCA) were also used further to validate the clinical efficacy of the nomograms. In the external validation set, the same validation is performed. Results: Of the 1998 patients screened from the SEER database with a pathological diagnosis of PNET, 343 (17.2%) had LMs at the time of diagnosis. The independent risk factors for the occurrence of LMs in PNET patients included histological grade, N stage, surgery, chemotherapy, tumor size and bone metastasis. According to Cox regression analysis, we found that histological subtype, histological grade, surgery, age, and brain metastasis were independent prognostic factors for PNET patients with LMs. Based on these factors, the two nomograms demonstrated good performance in model evaluation. Conclusion: We developed two clinically significant predictive models to aid physicians in personalized clinical decision-makings. [ABSTRACT FROM AUTHOR]