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In recent years, deep learning has become the mainstream development direction in the change detection field, and its accuracy and speed have also reached a high level. However, the change detection method based on deep learning cannot predict all the change areas accurately, and its application is limited due to local prediction defects. For this reason, we propose an interactive change detection network (ICD) for very high resolution (VHR) based on a deep convolution neural network. The network integrates positive and negative click information in the distance layer of the change detection network, and users can correct the prediction defects by adding clicks. We carried out experiments on the open source dataset WHU and LEVIR-CD. By adding clicks, their F1-scores can reach 0.920 and 0.912, respectively, which are 4.3% and 4.2% higher than the original network. To better evaluate the correction ability of clicks, we propose a set of evaluation index—click correction ranges, which is suitable for evaluating clicks, and we carry out experiments on the above models. The results show that the method of adding clicks can effectively correct the prediction defects and improve the result accuracy.

Gadolinium-doped ceria (GDC) interlayers are required to prevent the interfacial reaction between La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) cathode and Y2O3-stabilized ZrO2 (YSZ) electrolyte in solid oxide fuel cells (SOFCs). However, it's difficult to prepare a thin and dense GDC interlayer on the sintered half-cell at a low temperature. In this study, the physical vapor deposition (PVD) method was employed to successfully manufacture dense GDC interlayers with the thickness of 1 μm. The influences of GDC sintering temperature (900 °C, 1000 °C and 1100 °C) on cell performance characteristics and degradation behavior were investigated. The cell with GDC interlayer sintered at 1100 °C showed the lowest degradation rate during the 216-h operation. The best stability was attributed to the most effective inhibition of Sr diffusion by the GDC interlayer, which was demonstrated by the almost unchanged Ohmic and polarization resistances during the aging stage and the negligible Sr enrichment at YSZ/GDC interface. Compared to the conventional screen-printed GDC interlayers (sintered above 1250 °C), the GDC interlayer prepared by the PVD method and sintered at 1100 °C was significantly denser and thinner, showing a promising application prospect due to its benefits for cell stability.

Hydrothermal reaction in Cerium and Gadolinium solution as an optimization method is developed and first reported for the densification of gadolinia doped ceria, the barrier layer between Zirconia electrolyte and (La,Sr)(Co,Fe)O3-δ cathode. This method is based on the hydrothermal reaction for nano particles in-situly grown on porous surface, to improve barrier layer density, alongside the sintering of cathode at 1075 °C. As a result, the ohmic resistance is prominently decreased by ∼16.4 % at 750 °C for electrolyte supported symmetrical cell. Whereas, the cathode polarization resistance is decreased by as much as a factor of ∼3 from 0.3702 Ω·cm2 to 0.1325 Ω·cm2 at 750 °C and p O 2 = 0.21 a t m . Furthermore, the anode supported cell exhibits higher open circuit voltage, smaller area specific resistance, elevated performance output and less degradation. And this modified barrier layer shows reduced Sr migration in 300 h operation at 750 °C. The hydrothermal reaction is demonstrated to prepare denser and sintering-active barrier layer with faster oxygen ion transfer and better interface connection, with large-scale application prospects and cost-competitiveness.

Solid oxide fuel cell combined with heat and power (SOFC-CHP) system is a distributed power generation system with low pollution and high efficiency. In this paper, a 10 kW SOFC-CHP system model using syngas was built in Aspen plus. Key operating parameters, such as steam to fuel ratio, stack temperature, reformer temperature, air flow rate, and air preheating temperature, were analyzed. Optimization was conducted based on the simulation results. Results suggest that higher steam to fuel ratio is beneficial to the electrical efficiency, but it might decrease the gross system efficiency. Higher stack and reformer temperatures contribute to the electrical efficiency, and the optimal operating temperatures of stack and reformer when considering the stack degradation are 750 °C and 700 °C, respectively. The air preheating temperature barely affects the electrical efficiency but affects the thermal efficiency and the gross system efficiency, the recommended value is around 600 °C under the reference condition.

Solid oxide fuel cells (SOFC) can directly convert chemical energy into electrical energy with high power generation efficiency. However, the power generation process is always accompanied by the release of heat, and the balance of heat and electricity is important to the safe and stable operation of the SOFC stack. In this paper, a semi-empirical model of a kilowatt-level SOFC stack was established based on the experiment data that was operated in Xuzhou HuaTsing Jingkun Energy Co. Ltd. Based on this model, the effects of different operating temperatures, fuel and air flow rates, air-to-hydrogen ratio and other factors on the thermoelectric balance were analyzed with hydrogen fuel. In addition, methanol was also selected to study the thermo-electric balance performance. The results shows that the SOFC stack would meet the thermal balance on a special voltage, called self-heating balance voltage, but which varies under different conditions. With the increase of the fuel and air flow rates, the self-heating balance voltage and the limited voltage that shows the heat is surpass the power are decreases clearly. However, the self-heating balance voltage and the limited voltage changes differently under different air-to-hydrogen ratios. The air-to-hydrogen ratio enlarges from 2.4 to 3.6, the self-heating balance voltage and the limited voltage decreases by -4.14% and -2.42% by increasing air rates, however changes 1.26% and -3.07% by decreasing hydrogen rates, respectively.

Solid oxide fuel cell (SOFC) is one of the new energy conversion technologies producing electricity and heat from fuel and oxidant through an electrochemical reaction. The high operating temperature has many advantages including high efficiency, flexible fuel adaptability and low emissions. However, it has also some drawbacks, e.g., thermal expansion mismatches among the involved materials, particularly when the temperature reaches around 1400 oC during the sintering process, which may cause non-uniform distribution of thermal stress and even further deformation and warpage observed in the cell manufacturing steps. A three-dimensional CFD (computational fluid dynamics) simulation model is developed to study the thermal stress distributed in the sintered function layers of the anode-supported planar SOFC unit cells (10×10 cm2) using a finite element method. Five layers are included, i.e., cathode and its separation layer (GDC/LSCF, 70 µm), anode support and active layers (Ni/YSZ, 550µm), and electrolyte layer (YSZ, 30 µm) between them. In terms of the thermal stress and deformation, the predicted results are presented and discussed for the sintered unit cells with different angels located around the four cornels. It is found that the maximum thermal stress occurs at the interface between the electrode and electrolyte; the magnitude and distribution of thermal stress at the interfaces are closely related to the material thermal properties; the maximum deformation about 13 mm in the thickness direction is predicted for the 90-angel shaped cornels at the sintering temperature 1400 oC, which is bigger than that for the case with the circular shaped cornels; the deformation magnitude depends not only on the maximum thermal stress, but also the difference between the maximum and minimum thermal stress. The findings and predicted results may be applied for optimization of design and sintering conditions for SOFC unit cells. Acknowledgements This work is supported by the National Key Research and Development Project of China (2018YFB1502204, 2018YFB1502203, 2018YFB1502205), the Ningbo major special projects of the Plan “Science and Technology Innovation 2025” (2018B10048). Figure 1

Electrical performance, durability and degradations are challenging issues for Solid Oxide Fuel Cell (SOFC) commercialization. Ce0.9Gd0.1O2-δ (GDC) and La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) are current gold material system in SOFC, which mainly works as barrier layer and cathode, respectively. However, the porous GDC barrier layer and vulnerable cathode/electrolyte interface often leads to high ohmic resistances and fast degradations. Herein, we develop and report a novel approach for barrier layer and cathode modifications, using cost-competitive and scalable hydrothermal reaction. Results show that, the as-sintered porous GDC barrier layer is filled up with in-situly grown Ceria based nano particles during hydrothermal reaction, yielding improved density and sintering-active surface, simultaneously. After co-sintered with cathode, the cell obtains optimized cathode/barrier layer interface, exhibiting decreased ohmic and cathode polarization resistances with higher electrical performance and less degradation. On the other aspect, the Ceria based nano particles are also observed in-situly precipitated on LSCF powder surface during hydrothermal reaction, forming dual-phase LSCF@GDC cathode, which also yields decreased ohmic and polarization resistance than pristine LSCF. Above results suggest that hydrothermal modifications are effective for barrier layer and cathode/electrolyte interface optimizations. Thus, the improved oxygen ion transfer and interface contact are beneficial for SOFC electrical performance and long-term operation. Furthermore, this hydrothermal modification is applicable in many other surface and interface optimizations.

Solid oxide fuel cell (SOFC) has attracted more and more attention in recent years due to its high efficiency and low pollution. However, lifetime and stability are still limitations that affect further commercial applications of the SOFC technology. Therefore, it is critical to establish an online monitoring and analysis method to study the mechanism of SOFC performance evolution. The initial performance evolution of SOFCs is more apparent and non-linear than the subsequent stages, affecting the performance calibration and trading, especially for the industrial large-size cells and stacks. In this study, a single cell with an effective area of 100 cm2 was tested in Xuzhou HuaTsing Jingkun Energy Co. Ltd. under the constant current condition with humidified H2 for 80 hours after the NiO-YSZ anode was reduced for 4 hours. During the operation, the EIS data under different DC electrical current biases (0, 20, 50, 100, 300 mA cm-2) and j-V curve were recorded at 24-hour intervals. The EIS data were decomposed by the distribution of relaxation time (DRT) method, and the evolution of each electrode process under different polarization conditions was obtained. For the first 22 hours, the voltage under galvanostatic test and the power density at 0.7 V increased. The performance improvement is mainly due to the increase of the OCV and the decrease of the anode gas diffusion as well as gas conversion resistance, which can be attributed to the further anode reduction. The long reduction time is related to the low porosity and fine granularity of the Ni-YSZ anode, which was preliminarily verified by FIB-SEM. During the next 60 hours, the voltage dropped rapidly, and the power density at 0.7 V decreased by 27%. This nonlinear degradation was mainly caused by the weakening of the charge transfer reactions at the anode and the O2 surface exchange kinetics at the cathode. With the increase of current density, the deterioration of anode reaction gradually became the dominant factor for the increase of polarization impedance.

In recent years, deep learning has become the mainstream development direction in the field of change detection, and its accuracy and speed have also reached high levels. However, a change detection method based on deep learning cannot accurately predict all change areas, and its applicability is limited due to local prediction defects. For this reason, we propose an interactive change detection (ICD) network for very-high-resolution (VHR) remote sensing images based on a deep convolutional neural network. Positive and negative click information is integrated in the distance layer of the change detection network, and users can correct prediction defects by adding clicks. We carry out experiments on the open source WHU dataset and the homemade GTMAP-ICD dataset. By adding clicks, the F1 coefficients achieved on these dataset can reach 0.833 and 0.819, respectively, which are 5.8% and 5.3% higher than those of the original network. To better evaluate the correction ability of clicks, we propose an evaluation index, the click correction range, which is suitable for the evaluation of clicks, and we carry out experiments on the above models. The results show that the method of adding clicks can effectively correct prediction defects and improve the accuracy of the obtained results.

In the commercialization of the solid oxide fuel cell (SOFC) technology, the long-term stability and the use of hydrocarbon fuels are important. An 18-layer SOFC stack with anode-supported cells was first designed, assembled and operated in Huatsing Power Co., Ltd in China. After the basic performance test with H2, the stack was operated at 750 °C with a 14.53 L/min hydrocarbon fuel for nearly 800 hours. The voltage degradation rate was only 1.42%/kh. Post analysis was performed through SEM and EDS. Microstructures of Ni particles with different degree of carbon deposition at the fuel inlet were observed and discussed. A phenomenon of rainbow-shaped color distributions on the surfaces of anode and nickel mesh in every layer was found. This phenomenon was related to the oxidation of the upper part of the nickel contact layer. Due to the light interference taking place at the nickel-oxide-air interfaces, different thickness of oxide film led to different colors. Carbon deposition and oxide film of nickel contact layer with non-uniform thickness were the possible causes of degradation.

In this work, the electrical and electrochemical performances of LaNi0.6Fe0.4O3 (LNF) cathode contact and current collecting layer are investigated. The screen-printed LNF thin film on LSCF-GDC cathode effectively improves the performance of anode supported single cell with maximum power density increase by ∼15% and polarization resistance decrement by ∼24%. However, the LNF layer is found to hinder oxygen diffusion under low cathode oxygen partial pressure below ∼0.07 atm. For the application as thick contact layer, an optimized method is developed in combination with alternate ink deposition and drying processes, to provide decent structural stability and interfacial contact. The area specific resistance (ASR) of thick LNF contact layer shows high long-term stability under current load of 300 mA cm−2. The ASR stabilizes at 0.086 Ω·cm2 for more than 1600 h. Moreover, the LNF contact layer operates stably after 7 thermal cycles. The results indicate that, LNF is promisingly applicable as current contact and collecting material in solid oxide fuel cells.

High fuel utilization rate is the basis for solid oxide fuel cells (SOFCs) to achieve high power generation efficiency. However, the severe concentration polarization, namely limiting current behavior, hinders cell performances in the situation of high utilization rates. In this work, a planar SOFC with 10 × 10 cm2 working area is tested using both voltammetry and electrochemical impedance spectroscopy (EIS) at various air and fuel flow rates. Cell resistance is obtained from the smoothed derivatives of voltage vs. current curves as well as the Nyquist plots of EIS results. It is found that resistance vs. current plots reveal the limiting current behavior better than voltage vs. current curves. It is indicated that cell resistance is a more suitable and robust criterion for the limiting current behavior of fuel cells. It is also found that the high reactant utilization rate leading to the limiting current behavior is stable. This finding can provide useful information about fuel sensitivity analysis. Overall, cell resistance is a useful indicator that quantitatively describes the working status of SOFCs. Setting a resistance threshold is a good option to maintain safe and healthy operating status, especially for industrial SOFCs.

Detailed explanation and reliable quantification of the numerous degradation mechanisms contained in solid oxide fuel cells (SOFCs) are key issues to improve their durability. Although electrochemical impedance spectroscopy (EIS) has been widely used to unfold the complex and coupled physical/chemical processes, there are still some concerns with respect to the measurement and analysis procedures. In this study, an industrial-size cell (10 × 10 cm2) is tested to clarify the evolution of electrochemical characteristics during initial-stage operation, including 5 h of anode reduction, 32 h of activation process and 40 h of initial aging process. Detailed analysis of EIS measured under different DC bias is implemented through distribution of relaxation times (DRT) and subsequent equivalent circuit model (ECM) fitting to identify the contributions of individual processes to the rapid performance degradation during initial aging process. It is found that the deterioration of anode charge transfer reactions and ionic transport jointly causes more than 60% of the voltage degradation, followed by the O2 surface exchange kinetics coupled with O2- diffusion (17.3%), and then the anode gas conversion (13%). The microstructure deterioration of anode/electrolyte interface caused by Ni redistribution is regarded as the dominant degradation mechanism during initial aging process. A fast Ni migration mechanism is proposed to explain the observable Ni depletion in the anode functional layer, which is verified by detailed post-test characterization.

Stainless steel 441 was oxidized in water vapor containing atmospheres at 1,000 °C to study the contrary effects of water vapor on the oxidization process. The steel in 3.5 vol. % H2O containing atmosphere exhibited an relatively strong protective behavior. The reason was that the densification of the chromium oxide scale was promoted due to the sintering of the oxide grains via Cr-containing species vapor. But the oxidation of the steel in 11.5 ~ 15.6 vol. % H2O containing atmosphere followed a non-protective breakaway oxidation due to the breakage of the dense scale by “bubbles” and the formation of iron-rich oxides layer. Experimental result shows that the growth stress increased about 2 GPa during the first 70 ks in wet oxidizing atmosphere. The relatively slow increase of the oxides scale growth stress could be release in water vapor containing atmosphere.

Solid oxide fuel cells (SOFCs) provide a clean and efficient pathway to use a variety of carbon containing fuels for power generation. Reuse or recycle of the high-temperature off-gas can help to improve the fuel or air utilization of SOFC stacks, as well as to improve system efficiency and reduce operating costs. The off-gas utilization mode and its effect on the stack performance need to be further clarified. In this study, a novel semi-empirical parametric stack model was established based on the experimental data of a 3-cell SOFC stack. This parametric model can accurately predict the output performance of real stacks, which was verified by multi-condition experiments. Based on this stack model, one basic process and four off-gas utilization modes were designed and constructed. Comparative analysis of these modes under different operation parameters was carried out. The effects of key operation parameters, including fuel flow rate, operating current, stack temperature, pre-reformer temperature, split ratio and recycle ratio on the stack performance were studied, which were characterized by the electrical efficiency and exergy efficiency of the power module. It was found that the mode with two-stage stacks can get the maximum electrical efficiency (>45%) with the operating current less than 20 A, while the mode with anode off-gas recycled to the pre-reformer instead obtained the maximum electrical efficiency (>35%) when the specified current was larger than 25 A. A comprehensive and in-depth perspective on different stack off-gas utilization modes is provided, which can supply feasible guidance for the next-step overall system design. Besides, the stack modeling and process simulation method developed in this study can provide reference for related research.

The oxidation behavior of the stainless steel 441 in the initial 2 h was investigated gravimetrically at 600 °C–950 °C under various oxygen pressures. The morphology, composition and the growth stress of the scale on the oxidized alloy were analyzed by SEM/EDS and Raman spectra. It was found that the performances of the scale degraded with the temperature and oxygen pressure increasing. The oxidation of stainless steel 441 presented a multi-stages behavior. It was suggested that the first chemical reaction determining stage was the nonselective oxidation of steel surface. The following stage in pure oxygen ambient was the formation of chromium-oxide-mainly-containing layer. Kinetic mechanism of second stage oxidation changed from diffusion determining step (600–800 °C) to interface chemical reaction (900–950 °C) due to the decline of the protection of the oxides layer. Only linear rate law was obeyed in the lower oxygen pressure atmospheres at 800 and 900 °C within the initial 2 h.

Solid Oxide Fuel Cells (SOFCs) represent an attractive technology for the conversion of chemical to electrical energy because of their high efficiencies and low environmental impact. Additionally, they also have good fuel flexibility and long-term stability, which could direct utilize the hydrocarbon fuels and contribute to the more sparing utilisation of remaining fossil fuel reserves. Thus, they have been regarded as one of the most promising green power generation system in the near future. SOFC stacks are the key components of SOFC power generation system. Planar SOFC stack fabricated by assembling the planar single cells in series have the advantages of short current route and thereby of the low ohmic cell resistance, high power density and performance, simple structure, relatively easy fabrication process and low cost. However, it still has drawbacks of difficult sealing technique, low thermal cycle stability and high performance degradation. In this paper, the recent progress of the research and development on planar SOFC single cells and stacks are comprehensively reviewed, including the materials and structures of single cells, sealing strategy and types of sealants, design and materials of interconnects and the design and assembly of the stacks. The state of the art technologies and the current achievements of the companies and institutes which take the lead in SOFC field are introduced as well. Finally, some key issues need to be addressed for promoting the commercialization processes of planar SOFC stacks are put forward.

The micro Solid Oxide Fuel Cell-Combined Heat and Power (SOFC-CHP) System is one of the most promising technologies of distributed generation and has been commercialized in Japan and Europe. However, the performance degradation of an SOFC stack still exists, causing the ratio of power and heat to change and the Joule heat to increase in the stack. This phenomenon should not have been neglected. A zero-dimension SOFC model including basic Nernst, ohmic, activation and concentration voltage loss was used to simulate the micro SOFC-CHP system, and a degradation model was also applied to modeling the power change with respect to operating time in different situations. Both of the models were verified by real stacks experiment data and the effectiveness was proved in system-level modeling. Three key operating parameters of the system were promoted: stack current I, excess air factor α and fuel utilization Uf. Given the safe temperature ranges of an SOFC stack, combustor and reformer, the most appropriate parameter range was illustrated to be limited in a shape of a small triangle. Within the safe parameter range, while the excess air factor α was fixed at 2.64, the electrical efficiency reached a maximum 44.9% (HHV) at 120 A, while the electric power output of SOFC and hot water were both 5.58 kW. As for the dynamic modeling, by comparing constant current, constant voltage and constant power three operating patterns, results showed that the constant current pattern had the longest lifetime and the constant power pattern followed.

The reduced operating temperatures of SOFCs makes the possible of using metallic alloys as interconnect. Stainless steel 441 is one of the common studied materials for the interconnect component. The oxidation behavior of a stainless steel 441 in various oxygen pressure atmospheres in the initial 2 hours was investigated gravimetically in the temperature range of 600 ~ 950oC in the present work. And the morphology of the scale surface of oxidized alloy was observed by SEM, and the impacts of oxygen pressure and temperature on the oxidation were examined. The oxidation mechanisms were analyzed by Real Physical Picture model. Different oxidation kinetic processes were found in various exposure temperatures and oxygen pressures. In the case of 900~950 oC in pure oxygen, it obeyed two stages linear rate law. When the temperature was reduced to 600~800 oC in pure oxygen, the oxidation of 441 alloy followed linear-to-parabolic rate law. But only linear rate law was obeyed in the lower oxygen pressure atmospheres at 800 and 900 oC in the initial 2 hours. The kinetic parameters of the alloy oxidation process were given.

Under the three-dimensional(3D) tendency in land-use,the two-dimension(2D) cadastre management model can not reflect the land-use of the vertical space and the property.It is essential to introduce the 3D cadastre management model.The previous scholars didn't put the relation between people,right and land administrative unit into consideration.This article analyzed the core classes of LADM in ISO/TC211,including LA_Party,LA_RRR,LA_BAUnit and LA_SpatialUnit,and their relationship.LADM get a thought of constructing administration units and space units separately.This allows for a separate introduction in LADM of the "legal/administrative part"(the registers) and of the "spatial part"(the cadastral map),e.g.first the registers,then the map.Considering the framework of LADM's core classes and the design concept of it,choosing a hybrid solution of combined 3D cadastre and 2D cadastre,the 3D cadastre concept model which is suitable for the current situation in China was proposed.In this model,the basic administrative unit consists of 2D and 3D entity of right,and the spatial unit consists of 2D space object and 3D space object,so there is a relationship of one-to-one between them.In order to meet the management need of land's spatial right,the model introduced the core class LA_SpatialUnit which covers building units,networks and other 3D cadastre forms.And based on facial model theory and the object-oriented thought,the data model of spatial unit was constructed.According to the concept model and spatial data model of the 3D cadastre,the 3D cadastre management model was designed and its prototype system was developed to verify the model's feasibility.Through the instance of the management of house property right units in Shenghe garden district and underground land parcel which locates in a commercial district,the model is confirmed to be viable in the 3D cadastre management in our country.