Feature distortions of data are a typical problem in remote sensing image classification, especially in the area of transfer learning. In addition, many transfer learning-based methods only focus on ...spectral information and fail to utilize spatial information of remote sensing images. To tackle these problems, we propose spectral-spatial weighted kernel manifold embedded distribution alignment (SSWK-MEDA) for remote sensing image classification. The proposed method applies a novel spatial information filter to effectively use similarity between nearby sample pixels and avoid the influence of nonsample pixels. Then, a complex kernel combining spatial kernel and spectral kernel with different weights is constructed to adaptively balance the relative importance of spectral and spatial information of the remote sensing image. Finally, we utilize the geometric structure of features in manifold space to solve the problem of feature distortions of remote sensing data in transfer learning scenarios. SSWK-MEDA provides a novel approach for the combination of transfer learning and remote sensing image characteristics. Extensive experiments have demonstrated that the proposed method is more effective than several state-of-the-art methods.
Instability of submarine slopes in Zhoushan Islands is widespread. Frequent submarine landslides pose a great threat to offshore facilities such as submarine optical cables, reclamation projects, ...ports and docks. In this paper, a self-developed in-situ observation system is used to observe the deformation of submarine slopes on the southwest side of Zhujiajian Island in Zhoushan Islands for 75 days. The results show that the deformation characteristics of sediments at different depths of the submarine slope are different, and the lateral deformation of bottom sediments is about 0.75 mm, which is three times as much as the deformation of overlying sediments. The deformation process presents a step-like change, and the deformation direction is consistent with the trend of submarine slope.
In this paper, an integrated energy storage system consisting of Compressed Carbon dioxide Energy Storage (CCES) and Organic Rankine Cycle (ORC) was proposed. Four criteria (system exergy efficiency, ...total cost rate of exergy destruction, total product unit cost, and total exergoeconomic factor) were defined to evaluate the system performance from exergy and exergoeconomic points of view. The influence of key parameters on system performance was analyzed, and multi-objective optimization of the system was conducted. The results showed that for the base case, the net power output, system exergy efficiency, and total product unit cost were 27.736 MW, 66.64%, and 20.34 $/GJ, respectively. Recuperator had the largest exergy destruction (39.17% of the total exergy destruction) and a higher value of investment cost rate, signifying its necessity of optimization. Sensitivity analysis demonstrated the monotonic effects of compressor inlet temperature, turbine inlet temperature, and minimum temperature difference in heat exchangers on system performance, but for pressure ratio or pump2 outlet pressure, there was an optimal value for the system performance within the range of values studied. Finally, multi-objective optimization recommended a 72.6% for system exergy efficiency, 452.35 $/h for total cost rate of exergy destruction, and 18.49 $/GJ for total product unit cost.
•Exergoeconomic performance of an integrated system based on CCES and ORC is analyzed.•Recuperator has the largest exergy destruction in the integrated system.•There is an optimal pressure ratio to make system performance best.•Multi-objective optimization of the integrated system is conducted by NSGA-II.
Monitoring and early warning of submarine landslides could provide instant predictions for landslides, which is to avoid the destructive damage of submarine facilities such as pipelines and optical ...cable, etc effectively. However, researches on submarine landslide focus on numerical simulation and laboratory test, lacking support of in-situ observation data. This paper established the submarine landslide monitoring and early warning system by combining real-time monitoring data with web network platform and database technique. Based on the computational analysis of key monitoring parameters in the process of seabed deformation and sliding, the system has realized the accurate prediction and early warning of submarine landslides. The system has been applied to the submarine landslide monitoring in Zhoushan sea area, Zhejiang province, China, which has ensured the safety of offshore platforms and submarine projects in this area. The establishment of this system provides a new idea and method for submarine landslide warning.
With the continuous expansion of human activities to the ocean and the development of marine engineering, the stability of submarine landslides has attracted increasing attention. Monitoring data of ...the stability of submarine landslides under the action of strong wind and waves remain lacking because of limited observation technology and complex real sea conditions. This paper reports the long-term and continuous stability monitoring of submarine landslides under the action of wind and waves in the seabed of the Zhujiajian landslide area of Zhoushan by using a self-developed observation equipment. Effective data were collected, and variations in the pore pressure and displacement of seabed under the action of wind and waves were analyzed. Then, problems related to the change of displacement of seabed under the action of waves were explored. A typhoon event occurred during the observation period, and the significant wave height increased significantly from about 0.1 m under calm sea conditions to 0.5 m. The excess pore pressure in the sediment of 1 m under the seabed fluctuated obviously under the action of waves, with an amplitude of 2-4 kPa. By contrast, the amplitude of excess pore pressure oscillation was about 0.5 kPa under calm sea conditions, and the wave enhancement significantly increased the excess pore pressure oscillation in shallow sediments. The displacement of 0.5 mm occurred from 12 m to 13.5 m under the seabed, and the rapid accumulation or large fluctuation of lateral displacement occurred at different depths during the three periods when the significant wave height peaked.
•An integrated energy storage system was thermodynamically analyzed.•Conventional and advanced exergy analyses were conducted.•Conventional exergy analysis showed that LRHE should be firstly ...improved.•Advanced exergy analysis revealed that ROHE should be firstly improved.•The exergy efficiency difference between real and unavoidable conditions was 9.22%.
In this paper, an integrated energy storage system based on transcritical CO2 energy storage and Organic Rankine Cycle (ORC) is proposed. The working fluid of ORC cycle is R290 and the cold energy of LNG is utilized as the heat sink. The performance of the system is analyzed using conventional and advanced exergy analyses. The conventional exergy analysis quantifies the exergy destruction of each component independently and showed the exergy destruction of LRHE was the largest. The advanced exergy analysis considers the interconnections among the components of the system and the technical limitations of each component, which can reveal more valuable information. The results showed that the R290-Thermal oil heat exchanger had the greatest potential for improvement due to the largest avoidable exergy destruction rate of 171.679 kW. The unavoidable exergy destruction rate of the LNG-R290 heat exchanger was the largest, sharing 35.66% of total unavoidable exergy destruction. A comparison between the results of the two analysis methods showed the advanced exergy analysis gave more reasonable suggestions in terms of system optimization. Besides, the system exergy efficiency was 34.62% under real condition and the theoretical maximum for unavoidable condition was 43.48%, meaning great potential for the improvement of system performance.
•A novel energy storage system based on carbon dioxide Brayton cycle is proposed.•Low-temperature thermal storage and cold energy storage are adopted in the system.•The storage of thermal energy and ...cold energy can meet the demand for utilization.•There exists an optimal pressure ratio to maximize power and exergy efficiencies.•In heat exchangers, heat exchanger3 should be given priority for better performance.
Low-temperature energy storage system is an important development direction of physical energy storage technology, which can avoid the technical difficulties caused by high-temperature conditions. In this paper, a novel physical energy storage system based on carbon dioxide Brayton cycle, low-temperature thermal storage, and cold energy storage was proposed. Water was chosen as the working medium for thermal storage, and ice slurry was chosen as the working medium for cold energy storage. The working processes of this low-temperature carbon dioxide energy storage system were introduced in detail and the corresponding thermodynamic model was established. In addition to the evaluation based on power efficiency and exergy efficiency, thermal energy utilization efficiency and cold energy utilization efficiency were defined to assess the feasibility of the independent operation of the system. Parametric analysis was carried out to analyze the effects of several important parameters on system performance. The results showed that, for the system under the basic working condition, power efficiency was 55.7%, exergy efficiency was 52.87%, thermal energy utilization efficiency was 83.3% and cold energy utilization efficiency was 89.5%. The total exergy destruction was 48.07 kW and the largest exergy destruction came from the compressor. According to the sensitivity analysis, in turbomachinery, turbine efficiency had the greatest influence on power efficiency as well as exergy efficiency, and when turbine efficiency increased by 1%, both power efficiency and exergy efficiency increased by 0.634%. There was an optimum for pressure ratio to get the maximum values of power efficiency and exergy efficiency, and the optimum was 6.5. The decrease of the pressure drop in heat exchangers could increase power efficiency and exergy efficiency whereas the decrease of minimum temperature difference in heat exchangers could increase the four efficiencies. Measured in terms of the degree of influence, heat exchanger3 had the greatest influence and should be paid more attention. As to the cooling medium, the increase of the inlet temperature of water could increase power efficiency and exergy efficiency. Besides, there was an optimum for the mass flow rate of water to maximize power efficiency and exergy efficiency. Finally, it should be noted that, to ensure that the storage of cold energy during the charge process could meet the demand of cold energy during the discharge process, all the parameters studied needed to be carefully set. Relevant research provided important guidance for understanding the thermodynamic performance of the low-temperature energy storage system with carbon dioxide as the working fluid.
Most transfer learning methods have the problem of insufficient distance constraint that plays a very important role in improving image classification performance. Therefore, this letter proposes a ...new method called joint distance transfer metric learning (JDTML) for remote-sensing image classification. First, the JDTML method establishes the constraints of marginal distribution, intraclass distance, interclass distance, and intraclass divergence based on the maximum mean discrepancy. Second, the objective function is to combine these constraints. So, JDTML can not only reduce the differences between the two domains on the whole and in each class, but also gather the samples of the same class and expand the distance from each class to the rest classes. By solving the objective function, the transfer metric matrix is obtained. Finally, the source and target domains are transferred to a common subspace for dimension reduction. The data after dimension reduction is used for classification, and the accuracy of classification is improved by iteration. The experimental results show that JDTML is more accurate than other methods compared.
Countries have sought to stop the spread of coronavirus disease 2019 (COVID-19) by severely restricting travel and in-person commercial activities. Here, we analyse the supply-chain effects of a set ...of idealized lockdown scenarios, using the latest global trade modelling framework. We find that supply-chain losses that are related to initial COVID-19 lockdowns are largely dependent on the number of countries imposing restrictions and that losses are more sensitive to the duration of a lockdown than its strictness. However, a longer containment that can eradicate the disease imposes a smaller loss than shorter ones. Earlier, stricter and shorter lockdowns can minimize overall losses. A 'go-slow' approach to lifting restrictions may reduce overall damages if it avoids the need for further lockdowns. Regardless of the strategy, the complexity of global supply chains will magnify losses beyond the direct effects of COVID-19. Thus, pandemic control is a public good that requires collective efforts and support to lower-capacity countries.
The relationship between three scoring systems (LODS, OASIS, and SAPS II) and in-hospital mortality of intensive care patients with ST segment elevation myocardial infarction (STEMI) is currently ...inconclusive. The baseline data, LODS score, OASIS score, SAPS II score, and in-hospital prognosis of intensive care patients with STEMI were retrieved from the Medical Information Mart for Intensive Care IV database. Propensity score matching analysis was performed to reduce bias. Receiver operating characteristic curves (ROC) were drawn for the three scoring systems, and comparisons between the areas under the ROC curves (AUC) were conducted. Decision curve analysis (DCA) was performed to determine the net benefits of the three scoring systems. LODS and SAPS II were independent risk factors for in-hospital mortality. For the study cohort, the AUCs of LODS, OASIS, SAPS II were 0.867, 0.827, and 0.894; after PSM, the AUCs of LODS, OASIS, SAPS II were 0.877, 0.821, and 0.881. A stratified analysis of the patients who underwent percutaneous coronary intervention/coronary artery bypass grafting (PCI/CABG) or not was conducted. In the PCI/CABG group, the AUCs of LODS, OASIS, SAPS II were 0.853, 0.825, and 0.867, while in the non-PCI/CABG group, the AUCs of LODS, OASIS, SAPS II were 0.857, 0.804, and 0.897. The results of the Z test suggest that the predictive value of LODS and SAPS II was not statistically different, but both were higher than OASIS. According to the DCA, the net clinical benefit of LODS was the greatest. LODS and SAPS II have excellent predictive value, and in most cases, both were higher than OASIS. With a more concise composition and greater clinical benefit, LODS may be a better predictor of in-hospital mortality for intensive care patients with STEMI.
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