A Comparison of Sentinel-1 Biased and Unbiased Coherence for Crop Monitoring and Classification

Synthetic Aperture Radar (SAR) holds significant potential for applications in crop monitoring and classification. Interferometric SAR (InSAR) coherence proves effective in monitoring crop growth. Currently, the coherence based on the maximum likelihood estimator is biased towards low coherence values. Therefore, the main aim of this work is to access the performance of Sentinel-1 time-series biased coherence and unbiased coherence in crop monitoring and classification. This study was conducted during the 2018 growing season (April-October) in Komoka, an agricultural region in southwestern Ontario, Canada, primarily cultivating three crops: soybean, corn, and winter wheat. To verify the ability of coherence to monitor crops, a linear correlation coefficient between temporal coherence and dual polarimetric radar vegetation index (DpRVI) was fitted. The results revealed a stable correlation between temporal coherence and DpRVI time-series, with the highest correlation observed for soybean (0.7 < R < 0.8), followed by wheat and corn. Notably, unbiased coherence of the VV channel exhibited the highest correlation (R > 0.75). In addition, we applied unbiased coherence to crop classification. The results show that unbiased coherence exhibits very promising classification performance, with the overall accuracy (84.83%) and kappa coefficient (0.76) of VV improved by 8.35% and 0.12, respectively, over biased coherence, and the overall accuracy (73.25%) and kappa coefficient (0.57) of VH improved by 7.56% and 0.14, respectively, over biased coherence, and all crop classification accuracies were also effectively improved. This study demonstrates the feasibility of coherence monitoring of crops and provides new insights in enhancing the higher separability of crops

µFuncCache: A User-Side Lightweight Cache System for Public FaaS Platforms

Building cloud-native applications based on public “Function as a Service” (FaaS) platforms has become an attractive way to improve business roll-out speed and elasticity, as well as reduce cloud usage costs. Applications based on FaaS are usually designed with multiple different cloud functions based on their functionality, and there will be call relationships between cloud functions. At the same time, each cloud function may depend on other services provided by cloud providers, such as object storage services, database services, and file storage services. When there is a call relationship between cloud functions, or between cloud functions and other services, a certain delay will occur, and the delay will increase with the length of the call chain, thereby affecting the quality of application services and user experience. Therefore, we introduce μFuncCache, a user-side lightweight caching mechanism to speed up data access for public FaaS services, fully utilizing the container delay destruction mechanism and over-booked memory commonly found in public FaaS platforms, to reduce function call latency without the need to perceive and modify the internal architecture of public clouds. Experiments in different application scenarios have shown that μFuncCache can effectively improve the performance of FaaS applications by consuming only a small amount of additional resources, while achieving a maximum reduction of 97% in latency

Research Status and Development of Non-Ferrous Metal Beneficiation Wastewater Treatment

Non-ferrous metal beneficiation wastewater is often acidic or alkaline, and contains a large number of residual reagents, suspended solids and metal ions-based pollutants. With the continuous development and utilization of mineral resources, non-ferrous metal beneficiation wastewater has become a major cause of mine environment, water and soil pollution. The wastewater from mineral processing can not be applied to mineral processing. This was accounted by the fact that all kinds of pollutants can damage mineral processing equipment, affect mineral processing flowsheet and decrease concentrate quality. Therefore, the comprehensive treatment of non-ferrous metal beneficiation wastewater has become an urgent problem that needs to be solved in China and even in the world. This article summarizes the treatment methods of the main pollutants that are generated from non-ferrous metal beneficiation wastewater, expounds the current research status of non-ferrous metal beneficiation wastewater treatment in recent years, looks forward to future development direction of wastewater treatment

Highly efficient Co3O4/Co@NCs bifunctional oxygen electrocatalysts for long life rechargeable Zn-air batteries

© 2020 Elsevier Ltd Rational design and synthesis of high-performance bifunctional oxygen electrocatalysts are in high demand for metal air batteries. Herein, Co3O4/Co nano-heterojunctions tailored in nitrogen-doped porous graphitized carbon frameworks (Co3O4/Co@NCs) are synthesized via annealing Co-based metal-organic-frameworks (Co-based MOFs). This structure for electrocatalysts with a combination of mixed metallic Co species and encapsulating porous graphitized carbon offers an efficient charge/mass transport environment. In addition, the Co3O4/Co nano-heterostructured interfaces serve as efficient reactive sites to enhance oxygen electrocatalysis. Furthermore, the strong binding forces between nanoparticles and carbon frameworks through Co–N covalent bonds prevent the loss of nanoparticles from the electrocatalysts, providing outstanding durability. Consequently, Co3O4/Co@NCs surpasses the performance of noble-metal catalysts with a positive half-wave potential of 0.92 V (vs. reversible hydrogen electrode, RHE) for the oxygen reduction reaction and a low potential of 1.55 V at 10 mA cm−2 for the oxygen evolution reaction. Impressively, our assembled zinc–air batteries using Co3O4/Co@NCs as the rechargeable air electrode exhibit superior charge-discharge performance and ultra-stable cyclability with almost no increase in polarization even after 600 h (10 mA cm−2), possessing great potential for practical application in next-generation rechargeable batteries