An Adaptive Backstepping Sliding Mode Cascade-Control Method for a DC Microgrid Based on Nonlinear Virtual Inertia

In order to improve the bus voltage robustness of distributed multi-source DC microgrid, a new cascade control method based on nonlinear virtual inertia and adaptive backstepping sliding mode is proposed. Firstly, the mathematical model of distributed multi-source DC microgrid with a buck–boost interface converter is analyzed and established. A nonlinear virtual inertia control method based on a variable droop coefficient is given by introducing the converter output voltage variation rate feedback term and a saturation function equation. Secondly, the voltage and current double closed-loop cascade controller is designed by using backstepping sliding mode control and adaptive algorithms. Finally, the system and cascade control models are built in MATLAB/Simulink for multi-case simulation. The feasibility and effectiveness of the proposed method is verified by comparing the results with traditional control methods

An Adaptive Backstepping Sliding Mode Cascade-Control Method for a DC Microgrid Based on Nonlinear Virtual Inertia

In order to improve the bus voltage robustness of distributed multi-source DC microgrid, a new cascade control method based on nonlinear virtual inertia and adaptive backstepping sliding mode is proposed. Firstly, the mathematical model of distributed multi-source DC microgrid with a buck–boost interface converter is analyzed and established. A nonlinear virtual inertia control method based on a variable droop coefficient is given by introducing the converter output voltage variation rate feedback term and a saturation function equation. Secondly, the voltage and current double closed-loop cascade controller is designed by using backstepping sliding mode control and adaptive algorithms. Finally, the system and cascade control models are built in MATLAB/Simulink for multi-case simulation. The feasibility and effectiveness of the proposed method is verified by comparing the results with traditional control methods

Mining Sequential Update Summarization with Hierarchical Text Analysis

The outbreak of unexpected news events such as large human accident or natural disaster brings about a new information access problem where traditional approaches fail. Mostly, news of these events shows characteristics that are early sparse and later redundant. Hence, it is very important to get updates and provide individuals with timely and important information of these incidents during their development, especially when being applied in wireless and mobile Internet of Things (IoT). In this paper, we define the problem of sequential update summarization extraction and present a new hierarchical update mining system which can broadcast with useful, new, and timely sentence-length updates about a developing event. The new system proposes a novel method, which incorporates techniques from topic-level and sentence-level summarization. To evaluate the performance of the proposed system, we apply it to the task of sequential update summarization of temporal summarization (TS) track at Text Retrieval Conference (TREC) 2013 to compute four measurements of the update mining system: the expected gain, expected latency gain, comprehensiveness, and latency comprehensiveness. Experimental results show that our proposed method has good performance

Learning Observer-Based Sensor Fault-Tolerant Control of Distributed Generation in an Islanded Microgrid for Bus Voltage Stability Enhancement

In order to improve robust operating performance and enhance bus voltage stability, a learning observer-based fault-tolerant control strategy is proposed for the distributed generation in islanded microgrid with sensor faults and uncertain disturbances. Firstly, the output feedback control theory and the linear matrix inequality method are used to design closed-loop controller for the voltage source inverter of distributed generation; secondly, a fault-tolerant model and control structure of the distributed generation in an islanded microgrid with sensor faults is analyzed. By employing the fault output signal conversion filter and proportional derivative type learning observer, the online estimation and real-time compensation of the sensor fault signal are realized. Thirdly, the system synthesis of output feedback control and fault-tolerant control is completed. Finally, the multi-scenario sensor fault scheme simulation experiment verifies that the proposed control strategy has strong sensor fault tolerance and adaptability

A Symbiotic System of Irrigated Rice–Earthworm Improves Soil Properties and Rice Growth in Southern China

Earthworms have been studied in many ecosystems, demonstrating their high ecological value. However, there are few studies on the coupling of earthworms to irrigated paddy fields. On this basis, a symbiotic system of irrigated rice and earthworms was established with a wide-ridge cultivation model, and a combination of field experiments and pot experiments was carried out in Southern China. The results showed that the symbiosis of irrigated rice and earthworms in the pot experiment significantly loosened the soil by 5–10 cm, compacted the soil by 10–20 cm, increased the soil pH value by 0–10 cm, and increased the content of soil organic matter by 5–20 cm compared with rice monoculture. Due to the significant increase in leaf area index and grain weight at the mature stage, the white root at the heading and grain filling stages improved significantly, and the yield of irrigated rice also increased significantly by 15.39%. However, in the field experiment, due to the low survival rate of earthworms, the effect of inoculating earthworms was not significant. This study confirmed the beneficial effect of earthworm inoculation on the paddy field ecosystem, and provided a research basis for introducing earthworms into the paddy field ecosystem, realizing the sustainable development of rice cultivation, and ensuring world food security

A Symbiotic System of Irrigated Rice–Earthworm Improves Soil Properties and Rice Growth in Southern China

Earthworms have been studied in many ecosystems, demonstrating their high ecological value. However, there are few studies on the coupling of earthworms to irrigated paddy fields. On this basis, a symbiotic system of irrigated rice and earthworms was established with a wide-ridge cultivation model, and a combination of field experiments and pot experiments was carried out in Southern China. The results showed that the symbiosis of irrigated rice and earthworms in the pot experiment significantly loosened the soil by 5–10 cm, compacted the soil by 10–20 cm, increased the soil pH value by 0–10 cm, and increased the content of soil organic matter by 5–20 cm compared with rice monoculture. Due to the significant increase in leaf area index and grain weight at the mature stage, the white root at the heading and grain filling stages improved significantly, and the yield of irrigated rice also increased significantly by 15.39%. However, in the field experiment, due to the low survival rate of earthworms, the effect of inoculating earthworms was not significant. This study confirmed the beneficial effect of earthworm inoculation on the paddy field ecosystem, and provided a research basis for introducing earthworms into the paddy field ecosystem, realizing the sustainable development of rice cultivation, and ensuring world food security

Volatile carbonyl compounds’ retaining behavior of cellulose acetate cigarette filter along its axial direction

In order to investigate the filtration effects of cellulose acetate (CA) on volatile carbonyl compounds, axial sectional cellulose acetate filter samples and filter samples with harm reduction materials were prepared. Results showed that cellulose acetate filter had better filtration effects on crotonaldehyde(53%), propionaldehyde(57.66%) and formaldehyde (38.35%) and filtration rate decreased as cigarette mainstream smoke flowed towards the mouth end. When harm reduction materials were added to the section away from tobacco end, the filter showed better filtration effect

Review of Rice–Fish–Duck Symbiosis System in China—One of the Globally Important Ingenious Agricultural Heritage Systems (GIAHS)

The Chinese rice–fish–duck symbiosis system is one of the globally important agricultural heritage systems, with a history of nearly a thousand years. It embodies the wisdom of the Chinese ancestors and has huge comprehensive value, which has extremely important references for the sustainable development of agriculture. The technological core for the rice–fish–duck symbiosis system lies in the selection of rice, fish, and duck varieties and the coupling of agricultural operation time. In the process of modern agriculture, many varieties with high comprehensive benefits have also been applied to the rice–fish–duck system, and the rice–fish–duck model has been further developed. What is worrying is that the transfer of rural labor, the promotion of modern agricultural technology, the low degree of marketization and industrialization, the weakening of cultural awareness, and the change in climate have posed huge threats and challenges to the traditional Chinese rice–fish–duck system. The protection and development of the system are urgently needed. Therefore, we recommend delimiting active protection areas, establishing scientific research bases, improving relevant systems, developing rural tourism markets, and innovating farming technology, which also provide guidance for protecting and developing other agricultural cultural heritages

Review of Rice–Fish–Duck Symbiosis System in China—One of the Globally Important Ingenious Agricultural Heritage Systems (GIAHS)

The Chinese rice–fish–duck symbiosis system is one of the globally important agricultural heritage systems, with a history of nearly a thousand years. It embodies the wisdom of the Chinese ancestors and has huge comprehensive value, which has extremely important references for the sustainable development of agriculture. The technological core for the rice–fish–duck symbiosis system lies in the selection of rice, fish, and duck varieties and the coupling of agricultural operation time. In the process of modern agriculture, many varieties with high comprehensive benefits have also been applied to the rice–fish–duck system, and the rice–fish–duck model has been further developed. What is worrying is that the transfer of rural labor, the promotion of modern agricultural technology, the low degree of marketization and industrialization, the weakening of cultural awareness, and the change in climate have posed huge threats and challenges to the traditional Chinese rice–fish–duck system. The protection and development of the system are urgently needed. Therefore, we recommend delimiting active protection areas, establishing scientific research bases, improving relevant systems, developing rural tourism markets, and innovating farming technology, which also provide guidance for protecting and developing other agricultural cultural heritages