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With the increasing demand for straw resource utilization under the rice-wheat rotation system in the middle and lower reaches of the Yangtze River, less tillage or no-tillage (conservation tillage) on rice stubble fields has become a new trend. A large amount of residual surface straw can easily cause the entanglement and blockage of the soil-contacting parts for the no-till planter, which leads to a sharp increase in power consumption and a decrease in passability of the machine. To predict and evaluate the performance of the soil-contacting components for no-tillage planters, it’s necessary to establish the interaction model of the implement-soil coupling system. Traditional models regard the straw scattered on the soil surface as a rigid body and fail to simulate the rupture and deformation characteristics of the straw under rotary tillage operating conditions, which reduces the prediction accuracy of the model. In order to overcome the shortcomings of the previous models, an improved flexible model of the straw was proposed and the corresponding discrete element model of the tool-straw-soil coupling system was constructed considering the effect of scattered straw on the soil surface was constructed in this work. The soil and straw model parameters were calibrated by repose angle and compression experiments, respectively. Then, the correctness of the improved straw model was verified by soil bin test. At the same time, in order to solve the winding and obstructing problems caused by the operation of the standard rotary blade, a novel structure scheme of trapezoidal straight blade is designed. On this basis, straw displacement, shaft torque, stubble crushing and burying performance of both standard and trapezoidal straight blades under rotary tillage conditions are analyzed. Simulation results show that the existence of straw flexibility reduces the displacement of the straw, and plays a buffering role in the interaction between the straw and the cutter. The standard blade has a larger soil disturbance ability and causes the straw to move a longer distance, while the trapezoidal straight blade has a stronger stubble smashing ability after breaking the soil as a result of sharp blade edge. Stubble crushing and burying performance of the trapezoidal straight blade is better than that of the standard blade and the groove section shapes of both standard and trapezoidal straight blades under rotary tillage conditions are trapezoidal and triangular, respectively. The groove depth of the standard blade is 57 mm and that of the trapezoidal straight blade is 52 mm. The bending structure of standard blade causes a large amount of soil to be scattered in the seed ditch, especially when the depth of furrow is large, which will lead to the phenomenon of over-burying and affect the development of seeds. After the trapezoidal straight blade operation, the shape of the groove is more regular, and the residual soil is less. Triangular impact peak exits in the torque of the cutter shaft. The torque of the cutter shaft under the operation of the trapezoidal straight blade is greater than that of standard blade, while the soil breaking performance of the standard blade is better than that of the trapezoidal straight blade. In addition, taking the bending angle, flank angle and blade height as design variables, the influence of the variance and the interaction of design variables on the regression model was analyzed using the response surface method and the simplified regression equation of the objective function (rotary tillage torque and soil breakage rate) was determined. Based on the NSGA-II algorithm, the structure of the trapezoidal straight blade is optimized, and the optimal structural parameters are determined as follows: bending angle (150°), flank angle (60°), and blade height (88 mm). Through the comparative analysis of field experiments, it can be seen that the average torque and peak torque of cutter shaft were reduced by 11.70% and 6.28%, respectively, and the soil breaking rate is increased from 82.53% to 89.22%, which verifies the effectiveness of the optimization design of the tool structure. [ABSTRACT FROM AUTHOR]

Entity relation extraction is a fundamental task to detect a list of triplets, including two entities and the semantic relations between them. An overlapping relationship has caused the low performance of standard entity relation extraction in fishery in recent years. In this study, a novel entity relation extraction was proposed in fishery using the dual attention mechanism. First, a sentence classification and labeling strategy were selected to solve the difficulty in labeling overlapping relations in fishery standard texts. Second, an extraction model of standard entity relationship was established using a combination of dual attention, and Bidirectional Encoder Representations from Transformers-Bi-directional Long Short-Term Memory-Conditional Random Field (BERT-BiLSTM-CRF). Five components were included from the bottom to top: BERT layer, BiLSTM layer, word attention mechanism, sentence attention, and CRF output layer. In the pre-trained BERT model, the dual-layer two-way conversion and decoding were used to automatically learn sentence features for the vector representation. In the BiLSTM model, the context feature of the target entity was learned from the BERT output. The word and sentence level attention was utilized to optimize the weight of target words and sentences in the paragraph, including the noise removal, and the accuracy of relationship extraction. The CRF decoder was used to represent the output of the attention layer in the form of sequence tags. Finally, a comparative experiment was designed to verify the effectiveness of the model. The results show that better overall performance was achieved in the entity relationship extraction using the dual attention on the fishery standard interaction (DLOU-FSI) dataset, where the accuracy, recall, and F1 value were 92.67%, 92.31%, and 92.49%, respectively. The overlapping relations were effectively solved in the extraction of fishery standard relations. In addition, the recognition accuracy rates in the seven relation categories were all higher than others. The accuracy rate, recall rate, and F1 value were greatly improved by more than 90% in the quotation relationship, regulation, release, proposal, drafting, and centralization. Nevertheless, the recall rate of the improved model was dropped slightly in the comparison test. The reason was that there was a sparse distribution of sentence samples in the related category of comparative relations. In the DLOU-FSI corpus, each standard text of fishery contained only 0-3 comparison relation triples, less than 1% of the total number of all relational triples. As such, the comprehensive relationship features were necessary to learn for the higher recognition in the relationship extraction task. In addition, the quality of corpus was determined on the extraction of fishery standard text relations. The higher quality and the more accurate recognition of the model were achieved, as the deep learning model was trained to learn more data. There was also a critical value, after which the model cannot be greatly improved. In the case of a model adaptation, the test data can be effectively expanded to increase the number and diversity of samples for a better overall effect of relationship extraction. This finding can lay a significant foundation for the construction of fishery standard knowledge graphs. [ABSTRACT FROM AUTHOR]

Toilet revolution has become one important part of a rural revitalization strategy in China, aiming to effectively reduce the incidence rate of fecal oral diseases, while to ensure the health-care level and quality of human beings. Since 2018, the Ministry of Agriculture and Rural Affairs, together with relevant departments, has taken active actions to vigorously promote the rural toilet revolution and achieved positive effects. However, some situation, like “poor construction, not working well and improper use” of rural toilets, still occurs in some rural areas. The main reason is a lack of a standard system for the toilet modernization and utilization of excrement, further to improve the hygiene of toilets facilities in rural areas. Therefore, this study first summarized the 22 national and industry standards system that were directly related to rural toilet construction and excrement disposal in China. It was found that the number of existing standards was seriously insufficient, indicating the standard system has not been well-established for the rural toilet construction and excrement disposal in China. As such, this study aims to establish a three-dimensional structure diagram of rural toilet construction and excrement disposal, using the system engineering technology method, including levels (basic standards, general standards, special standards), sequence (product equipment standards, engineering construction standards, technical method standards, operation management standards, safety and health standards), category (rural household toilet standards, fecal sewage centralized treatment center standards, other standards). An optimal level of special standard was further determined, according to the basic established principles of a standard system for rural toilet construction and excrement disposal. The key content of a standard system construction was proposed to fill the research gaps in the basic national standards, and the general standards system, as well as in the special standards. Four recommendations were also proposed during this time: 1) To organize a special standardization working group or professional committee as soon as possible to systematically implement the policy of the toilet revolution; 2) To strengthen the fundamental research on the various advanced international standards systems; 3) To speed up the preparation of urgently needed standards systems; 4) To encourage the local governments to actively prepare the local standards system, in order to provide for the rural toilet revolution in China. The standard system of toilet modernization and utilization of excrement in rural areas can provide an important means to guide the renovation of toilet and the utilization of excrement as resources, further to standardize development of the modern industry. [ABSTRACT FROM AUTHOR]