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Aiming at the problems that SSA is prone to fall into local optimal and relatively low accuracy during search iteration. This paper proposed an enhanced sparrow search algorithm with multiple strategies (ESSA). At first, ESSA applied Lévy flight and cloud based adaptive weights to refine the original discoverers’ position update equation, which expanded the search range and enriched population diversity of the algorithm. Secondly, ESSA adopted a fuzzy control based adaptive lens imaging strategy to get the reversed position of the current optimal position to enhance the algorithm’s ability to jump out of local optimal. This paper selected 12 test functions from CEC2017 testbed as benchmark to evaluate the performance of ESSA with standard SSA, and other 4 improved sparrow algorithms: ISSA, MSSSA, HSSA, and SHSSA. Experiment result shows that ESSA can achieve the supreme results among evaluated algorithms. This paper also applied ESSA to the 3D UAV path planning problem. The simulation result illustrates that ESSA can also find the supreme 3D paths for UAV. [ABSTRACT FROM AUTHOR]

Objective The applicability of current China's natural gas analysis and testing standards under hydrogen-blended conditions needs to be confirmed ed to promote the standardization of hydrogen-blended natural gas. Methods By analyzing China's natural gas analysis and testing standards, 10 standards related to hydrogen-blended natural gas have been selected and the applicability of natural gas composition analysis standards and physical property calculation standards under hydrogen-blended conditions has been studied. Results The results show that the maximum hydrogen concentration specified by the natural gas composition analysis standard represented by GB/T 13610-2020 Analysis of natural gas composition-Gas chromatography and the physical property calculation standard represented by GB/T 17747.2-2011 Natural gas-Calculation of compression factor- Part 2: Calculation using molar-composition analysis is 10%, and the relevant standards need to be revised under the condition of high hydrogen concentration. Besides, if the hydrogen is not separated downstream, the interchangeability of natural gas and its standardization need to be studied urgently. Conclusions The proposed formulation and revision framework has reference significance for the future standardization work of hydrogen-blended natural gas. [ABSTRACT FROM AUTHOR]

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]

In order to solve the problems of unstable and low efficiency in the work space, a particle swarm optimization (PSO) algorithm with dynamic changes of inertia weight and learning factors was used to optimize the trajectory of 3-5-3 piecewise polynomial interpolation. Through the kinematic analysis of the forest work vehicle, four passing points in the working space were obtained, and the 3-5-3 piecewise polynomial interpolation was used for trajectory planning. Finally, the improved particle swarm optimization algorithm was used to optimize the trajectory running time under the kinematic constraints, and the optimization performance of the standard particle swarm optimization algorithm was compared. The results showed that the 3-5-3 piecewise polynomial interpolation curve using the improved particle swarm optimization algorithm had faster convergence speed, smaller fitness after convergence, and about 13% shorter running time, which effectively improved the working efficiency of the forest work vehicle. [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]

With high-rise buildings emerging, objective fear of heights detection is a key step in the standardization of the aerial work industry. Taking into account virtual reality, this paper designs an aerial exposure experiment, which studies the brain neural mechanism of fear of heights reaction, and proposes the functional brain network (FBN) to detect the fear of heights .By comparing the basic topological characteristics of FBNs, the brain regions closely related to fear of heights are found through thresholding. By dividing the community structures according to the brain regions, the recognition model of fear of heights is established . The results show that the more severe the fear of heights, the more complicated the FBN. The main brain regions involved in fear of heights include frontal lobe, central area, and occipital lobe. Using these brain regions to divide the community structures, the calculation accuracy of connection strengths on fear of heights can reach (97.37±0.58)%. [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]

BACKGROUND: Most scholars believe that the fracture of the lumbar spine and pedicle is stable, and transvertebral pedicle screw implantation can improve the stability of fractures. However, the diameter of the transvertebral pedicle screw, mechanical stability and safety of the vertebrae still remain controversial. OBJECTIVE: To analyze the effect of pedicle screws of different diameters and pedicle cortex on the mechanical stability of the fractured vertebrae and pedicle by three-dimensional finite element method. METHODS: Based on normal adult L2-L3 CT DICOM data, a mimics software was used to establish a model of the fracture at L2 vertebral body and the pedicle. At the same time, a three-dimensional model of L3 vertebra was created. The L2-L3 model was imported into 3-matic in stl format, and a model of pedicle screws with different diameters (diameter of 6.5 and 6.0 mm, and length of 45 mm) was established. The model was imported into ansys after the material attributes were assigned in the mimics software. A vertical load of 500 N was applied to the upper surface of the L2 vertebral body to simulate the biomechanical performance of a adult with standard body mass after implantation with transvertebral pedicle screw with different diameters under upright condition. RESULTS AND CONCLUSION: (1) After implantation with 6.0 mm screw, the equivalent load on the lower, upper, inner, and outer walls of the pedicle at the junction of the lumbar vertebra and the pedicle was (1.28±0.62), (0.95±0.18), (0.62±0.37), and (0.36±0.16) MPa, respectively. The difference was significant among groups (F=4.298, P < 0.05). (2) After implantation with 6.5 mm screw, the equivalent load on the lower, upper, inner, and outer walls of the pedicle at the junction of the lumbar vertebra and the pedicle was (1.82±0.76), (1.11±0.18), (0.93±0.38), and (0.43±0.14) MPa, respectively. The difference was significant among groups (F=7.034, P < 0.05). (3) The equivalent load on the lower, upper, inner, and outer walls of the 6.5 mm pedicle screw model was significantly higher than that on the 6.0 mm pedicle screw model (P < 0.05). (4) These results imply that the larger the pedicle screw is, the greater the load on the cortical bone at the junction of the lumbar vertebra and the pedicle is, and the stronger the holding force is. The load on the upper, lower, inner and outer walls of the pedicle is positively related to its cortical thickness. The cortical bone of the inferior wall is thickest, the equivalent load it bears is largest, and the cortical bone of the outer wall is thinnest, and it has the smallest equivalent load. The closer the pedicle screw is to the lower medial wall within the pedicle, the stronger the holding force and the better the stability. The closer it is to the upper and outer side walls, the smaller the gripping force and the worse the stability. However, the placement of nails on the upper and outer walls is safer than the placement of nails on the lower inner wall, and the pros and cons need to be weighed in accordance with the experience of the surgeon during placement. [ABSTRACT FROM AUTHOR]

In the Multi-objective evolutionary algorithm, the solution of the rank distribution takes up most of the computation time. According to the Pareto dominance relationship, this paper researched the solution of the rank and distribution, and found that there are some redundancy operation of rank and allocation in the classic methods. The classic algorithms need to rank all solutions, and select the next generation after sort, so it caused some unnecessary sort operations. To reduce the redundancy, this paper introduced a fast method of non-dominated sorting. The proposed algorithm only dealed the individual which belong the highest level in current population, and meanwhile it could choose individual into the next generation during the process of distribution level. When the next generation individuals were selected enough, the program was ended. This method reduced the number of the sorting of individuals, and also reduced the time complexity greatly. Then, it used three objectives optimization problem as an example, combined the fast non-dominated sorting method with the differential evolution algorithm, and proposed a fast three objective differential evolution algorithm based on non-dominated sorting. Finally, it compared this method with the famous ranking method and ENS/BNS method. The simulation results show that the proposed algorithm in time complexity and convergence speed is better than the classical method, and is not worse than the ENS/BNS algorithm. On the performance of the standard test function DTLZ1-DTLZ6, the proposed method is similar to or better than the comparison algorithms. The experiment verifies the correctness and effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Evaluating the comprehensive performance of high standard farmland construction project has important significance in the implementation of high standard farmland planning and government decision-making. On the bases of particle projection pursuit model (PP) optimized with swarm optimization (PSO) algorithm, investigation data, maps and statistic data of land use were used to build the index system for comprehensive performance evaluation of high standard farmland construction project in Dianjiang County, Chongqing. The results showed that: 1) Compared with the situation before the construction of high standard farmland, the contiguous degree of cultivated land increased by 13.56% , which indicated the improvement of the agricultural land flat condition. After the construction of high standard farmland, arable land showed significant discreteness, and the rate of terraced field increased significantly. The road accessibility also increased by 25% , which showed the improvement of the agricultural production conditions. Spatial dispersion slightly increased and agglomeration effect appeared after the project implementation. Road hardening rate were high in the middle and low at two sides of the area after high standards farmland construction. Irrigation guarantee rate and ditch density were improved apparently after high standards farmland construction, and the improved area was closely related to the industrial structure and terrain conditions in the south. The vegetation coverage rate of farmland ecological environment kept remarkably discrete during the whole process of the project. The thickness of effective soil layer increased obviously, and its spatial distribution is quite related with road accessibility. There existed big dispersion in the improvement of multiple subjects’satisfaction that both individual satisfaction and corporation satisfaction were high in southern crane platform areas after the implementation. The spatial distribution of newly increased annual income was evenly distributed after the high standards farmland construction. 2) As for the comprehensive effect evaluation, the comprehensive effect of Class I production area, accounting for 53.26% of the area, was the best where the multiple subjects’ satisfaction was promoted, the agricultural condition, the farmland ecological environment and the agricultural land flat condition were all improved. The overall comprehensive effect of Class II area, taking 37.62% of the area, was the second where the projection values of the four subgoals matched the effect and comprehensive results will be significant after the completion of the project. The comprehensive effect of Class III area, taking 9.12% of the area, was relatively poor where the projection values of the four subsystems were relatively low. Comprehensive evaluation of high standard farmland construction should take unique regional characteristics into consideration, formulate scientific and reasonable evaluation plan, and orderly perform differential evaluation. [ABSTRACT FROM AUTHOR]

Based on the variable amplitude loading tests of nine RC members, the possibility of giving the performance division standard for the damage process under different variable amplitudes according to the stiffness reduction index was studied. The influence of the duration of earthquake, peak displacement, longitudinal ratio and stirrup ratio on the damage of RC members were also discussed. It was found that the stiffness reduction index provided a unified standard of performance division for RC members under different variable amplitudes, and five performance levels (no damage, mild damage, moderate damage, severe damage and destruction) according to the capacity reduction index are proposed. The standard is verified by nine flexural failure specimens of rectangular section in the PEER database; The stiffness reduction index is in accordance with the peak deformation index in defining the light damage of RC members while the stiffness reduction index is in good agreement with the Park-Ang damage index in defining the moderate and severe damage of RC members. Based on the case study, the relationship between the stiffness reduction index and the stirrup ratio, and that between the effective duration and the ductility coefficient are discussed. [ABSTRACT FROM AUTHOR]