Agricultural Engineering
The vertical slit fishway has the characteristics of good flow conditions of water, clear location of the reflux zone, and strong adaptability to changes in upstream and downstream water levels. It is currently a high efficient and widely used fish passing engineering facility. In order to increase the effectiveness of fish migration in the research area, according to regulatory requirements, three types of fishway tank compartments were preliminarily designed, and numerical simulation methods were used to explore the impact of changes in baffle types on the flow structure of water of the tank compartments at a constant depth of 2 meters both upstream and downstream. The baffle type was optimized by analyzing the water flow pattern inside the pool, the velocity distribution at the vertical joints, and the energy dissipation effect. By changing the size of the second type of baffle, the width of the vertical joint was reduced from 0.6 m to 0.5 m. Under the premise of flow pattern of good water in the tank and flow velocity at the vertical joint, the maximum flow velocity near the vertical joint was reduced to less than the design flow velocity of 1.2 m/s; and the flow capacity of the optimized body under different conditions of equal water depth was calculated. When the water depth changed between 0.5 m and 2.0 m, the flow capacity of the fishway was between 0.236 m3/s and 0.951 m3/s. The flow pattern of good water inside the pool and the rationality of the velocity distribution at the vertical joints provided a good channel for the trace back of most fish in the study area, and the flow capacity at different water depths provided a reference for the operation and scheduling of the fishway.
Adjustment of agricultural planting structure is the main content of agricultural supply-side reform, and is also an important measure to promote farmers’ income. In order to study the impact of agricultural planting structure adjustment on agricultural mechanization, based on the panel data of 14 prefecture-level cities in Guangxi, we empirically analyzed the impact of agricultural planting structure adjustment on the development level of regional agricultural mechanization in Guangxi by the fixed-effect model. The results show that: the adjustment of agricultural planting structure has no direct impact on agricultural mechanization. Rural road facilities and agricultural operation scale have significant positive impact on the development level of regional agricultural mechanization. The increase of farmers’ income has a mediating effect on the development level of agricultural mechanization in Guangxi. According to the research results, the level of agricultural mechanization can be comprehensively improved by improving the rural infrastructure, promoting the moderate scale of agricultural operation, adjusting the agricultural planting structure and increasing farmers’ income.
In-depth study of the patent layout of the robotic milking machines in China is of great significance for Chinese technology research and protection. Based on the Derwent Innovation (DI) patent database, using the bibliometric method and topic clustering, the layout characteristics of the robotic milking machine in China are analyzed and summarized from the aspects of annual change of patent application, technology exporting country, patentee, patent legal status, classification defined by experts, IPC classification, research focus, etc. The analysis results showed that China started slowly in this field and entered a period of technological development in 2011. The key patentees of this technology were concentrated, the overall invalid patents accounted for 41%, and the patent maintenance was not strong. Foreign institutions had more effective patent ratios and technical directions in China than domestic institutions. Patent applications by foreign institutions accounted for 22.6%, mainly from Sweden, Germany, Netherlands and the United States, and patentees mainly included DeLaval and GEA. Among domestic institutions, Anhui Yomo Machinery Group Co. and Shandong Chengcheng Iot Technology Co. had more authorized and effective patents. Foreign institutions had more patents than Chinese institutions in advanced technology directions such as automatic teatcup attacher, automatic cluster remover, automatic teat identification equipment, mechanical arm and powerplant of automatic teatcup attacher or remover, automatic attaching or detaching of clusters. It is recommended that Chinese institutions should establish effective cooperation mechanisms such as patent pools, strengthen cooperation between companies, universities, and research institutions, and strengthen the overall patent layout and cutting-edge technology patent layout.
The study aims to use a cellular automata dynamic model with spatiotemporal features to simulate the calculation process of fruit and vegetable medium treated by a high voltage pulse electric field, and this simulation provides theoretical support for the application of high-voltage pulse electric field technology in fruits and vegetable preservation, drying, and sterilization. On the basis of considering the phenomenon and principle of cell breakdown in fruits and vegetables caused by high-voltage pulsed electric field treatment, a cellular automaton model for fruit and vegetable breakdown in the electric field was constructed by specifying the cellular space, state, and rules. The results showed that the simulation results of the experiment were in line with the breakdown characteristics of pulsed electric field treatment of fruit and vegetable media. The fitting degree was high compared with the actual situation, and the error was small. By using cellular automaton to simulate the model of pulsed electric field treatment of fruits and vegetable media, the breakdown process of fruits and vegetable media was reflected, which was beneficial to the application and promotion of pulsed electric field technology in the field of fruits and vegetables.
In order to avoid the overall structural damage caused by the failure of local components, a Venlo type greenhouse in Xianyang area was selected as the research object, and an improved sensitivity analysis method was applied based on the basic mechanism of continuous collapse resistance, and the key components of the continuous greenhouse structure and their distribution were obtained. The design and optimization of the greenhouse skeleton section was carried out by MIDAS-GEN software, and then the sensitivity coefficient of the column was determined by combining the demolition member method and the sensitivity analysis method in ANSYS software. The results showed that: (1) the sensitivity coefficient of the long side column was close to that of middle column and greater than that of the short side column, and the sensitivity coefficient of the short side column was greater than that of the corner column; (2) the sensitivity coefficient of the long side column near both ends increased significantly, and the column with truss hinged had a slightly higher sensitivity coefficient than that of other columns; (3) the sensitivity coefficient of the middle column showed a positive correlation with the direct stress, while the long and short column were opposites. The research results can provide a reference for the optimization of multi-span greenhouse and the study of continuous collapse resistance.
To promote the sustainable development of agriculture, improve the utilization efficiency of agricultural water resources, realize the mechanization and intelligence of the whole process of agricultural planting, and realize the yield increase and efficiency of root crops, the research progress of ridging and film mulching technology, ridging and film mulching machinery and film was summarized. It was found that China was relatively behind in intelligent agricultural machinery at present. The development idea of ridging, pipe laying and film mulching compound operation machinery was put forward to realize the effective utilization of water resources, mechanization of crop production and the intelligence control of dosage, and finally realize the yield increase and efficiency of root crops. It is expected to promote the further development of agricultural intelligence in the future.
To study the characteristics of different technologies and equipment of straw fuel utilization, and explore the appropriate mode and development path of straw fuel utilization in Northeast China, based on field investigation combined with practical operation experience and cost-effectiveness, this paper analyzes the current situation, process characteristics and development advantages of straw fuel utilization in Northeast China, and sums up three heating modes utilized in the region. The “one village, one factory” household straw briquette utilization mode is suitable for scattered residential rural area. The biomass boiler transformation heating mode is suitable for public institutions in villages and towns with large heating area and the cost can be decreased by 30% in heating period compared with coal-fired boiler. The straw bundled direct fired central heating mode with large and medium-sized boilers could be adapted in cities or towns and its cost is much lower, which can be decreased by 30%-36% in the heating period compared with coal-fired boiler. Finally, the countermeasures of strengthening organizational leadership, innovating development concept, perfecting market mechanism, paying attention to technical support, strengthening publicity and consciousness promotion are put forward based on the key problems existing in the utilization of straw fuel in Northeast China.
In order to explore the characteristics, advantages and disadvantages of cup-cover transplanting instead of plastic film application, taking appropriative cup and film as test materials,experiments were carried out to study the effect of two transplanting patterns (cup-cover and plastic film mulching) on yield, output value, quality and production cost of flue-cured tobacco. The cup-cover transplanting of tobacco played the role in warming, preventing insect, avoiding hail and water retention of soil through the "micro greenhouse" effect, and the product characteristics and agronomic standards were constructed. Compared with plastic film mulching, cup-cover increased average yield by 75.40 kg/hm2 and outcome by 2770.5 yuan/hm2, decreased plastic consumption by 60.00%and labor consumption by 63.40%. It had been popularized more than 70000 hectares because of its advantages of low consumption and environmental protection, although cup-cover transplanting had functional limitationin high altitude and low temperature areas. As a promising transplanting technology, cup-cover transplanting provides a new method for controlling residual film pollution.
Agricultural efficient water-saving service is an important means to promote the sustainable utilization of agricultural water-saving projects. Based on the field survey data of 2028 cotton farmers in south part, north part and east part of Xinjiang, this paper analyzed the behavior choices and paths of cotton farmers towards agricultural efficient water-saving services from the perspective of regional differences and cotton farmers' characteristics by using binary Logistic regression model. The results showed that, the significance of the government's promotion of efficient agricultural water-saving service on cotton farmers’ choice in southern Xinjiang, northern Xinjiang and eastern Xinjiang decreased in turn. The age of householder, education level and the proportion of household labor force had no significant influence on cotton farmers' choice of efficient water-saving agricultural service. The water-saving technical experience of householders, the degree of farmland fragmentation, the rate of irrigation water security and the number of water-saving irrigation service organizations had a significant influence on the cotton farmers' choice of efficient water-saving service behavior, and the influence degree was great. Finally, the paper proposed three development paths: improving water resources guarantee rate, strengthening scale management of small-scale farmers' land, and increasing the supply of efficient agricultural water-saving service organizations.
In order to explore the feasibility of wind-solar hybrid power generation in the field of facility agriculture, the central arid zone in Ningxia, which is rich in wind-solar resources, was selected as test area. Based on the existing foundation, a kind of solar greenhouse that can be powered by wind-solar hybrid power generation system is designed, and related indicators such as wind power generation and photovoltaic power generation were calculated and analyzed. The research shows that the wind and solar complementarity is good in the central part of Ningxia, which is suitable for the application of wind and solar hybrid power generation system. Under reasonable configuration, the annual power generation capacity of this power generation system is about 15481.3 kW·h, which can meet the routine use of daily greenhouses in spring, summer and autumn. Moreover, there is a surplus in power generation, and grid-connected power generation can be realized if conditions permit. In winter, due to the low temperature at night, the greenhouse needs to be heated by electric heaters, resulting in a sudden increase in power consumption, requiring an external power supply or other heating methods.
To effectively relieve the pressure from population, environment and resources, it is very important to develop plant factory. Intelligent plant factory is an advanced stage in the development of facility agriculture. It is a new topic to study how to apply machine learning in plant factory to effectively improve the production efficiency and promote the intelligent development of plant factory. Combining machine learning with crop phenotype study, a crop growth model is established and applied to plant growth environment monitoring (diseases, insects, grass, drought and water logging, nutrition, etc.), accurate plant factory indoor environment regulation, and intelligent nutrient solution regulation etc., so as to solve the problem of high cost and low crop yield of plant factories in China. The study can help plant factories develop towards the one with information technology, automation, intelligence, precision and individuation.
The purpose is to prepare a new type of mixed beverage with grains, oil crops and edible fungi as raw materials, and optimize the producing process. For grain crops, we chose Euryale ferox, barley and highland barley; for oil crops, we chose hazelnut, flaxseed and walnut; and for fungi, we chose Ganoderma lucidum, Hericium erinaceus and Cordyceps militaris. After the pretreatment of raw materials, the best raw materials and their best proportions for the beverage were determined through single factor experiment and orthogonal experiment respectively. The single factor results showed that the compatibility of Euryale ferox, hazelnut and Ganoderma lucidum was the best. The orthogonal test results showed that when the ratio of Euryale ferox, hazelnut and Ganoderma lucidum was 7:2:0.8, the taste of the compound beverage was the best, and the sensory evaluation score reached 88.5. In conclusion, the compound beverage prepared with 70% Euryale ferox, 20% hazelnut, 8% Ganoderma lucidum, 5% white granulated sugar, 0.15% citric acid and 0.02% compound stabilizer has the strongest flavor and sweet taste, which is suitable for consumers and is a new health beverage with development potential.
In order to solve the problems of traditional solar greenhouses such as poor resistance to natural disasters and low soil utilization efficiency, a new type of prefabricated heterogeneous composite wall solar greenhouse is proposed. The greenhouse is composed of a bone structure forming a load-bearing structure, and the wall is composed of a heat storage layer and an insulation layer, with a thickness of only 30 cm, which realizes the efficient use of land resources. This study mainly tested and analyzed the winter application effect of the greenhouse, and arranged 31 temperatures, 1 solar irradiance and 1 outdoor wind speed measurement point in the greenhouse and outdoor respectively. The results showed that under continuous cloudy days, the daily minimum air temperature range in the greenhouse was 6.5-8.9℃, the daily minimum temperature range of soil was 15.3-18.2℃, and the minimum temperature range of the internal surface of the greenhouse wall was 6.5-9.6℃, which were all maintained within the suitable growth temperature range of tomatoes. At the same time, the indoor temperature of the greenhouse was analyzed continuously for one month, and there was no temperature lower than the minimum tolerance temperature of tomatoes. The designed greenhouse has good thermal insulation and heat storage properties under the unfavorable condition of continuous cloudy days, which can realize the overwintering production of tomatoes. This study can provide a certain theoretical basis for the construction and development of prefabricated solar greenhouses and the selection of new composite wall materials.
To calculate the probability of disasters caused by different hazard winds to facility agriculture in Hubei Province, and analyze the change characteristics of disaster-causing winds, based on the meteorological datasets of each city in Hubei from 1991 to 2020, this study defined the indexes of mild, moderate, severe, and extra-heavy grade of wind disasters by double-condition constraints. The results showed that the greater the wind speed, the larger the disaster probability of facility agriculture was. The days of hazard winds were evenly distributed over the four seasons, and the days in spring and summer were greater than that in autumn and winter. The Ensemble Empirical Mode Decomposition (EEMD) analysis results showed that there were quasi-periodic changes of about 2-3 years, 6 years and 15 years in the disaster-causing wind force of facility agriculture in Hubei and the disaster-causing wind force remained stable until 2008. Since then, it showed a significant upward trend, and the number of disaster-causing wind days might increase in the future. The overall wind disaster risk in facility greenhouses was high in the central of the province and low in the east and west. The risk of wind disaster in Xiangyang was the greatest. In summary, the following cities, including Xiaogan, Enshi, Wuhan, Yichang, Huanggang, Shiyan, and Xianning, are at mild to moderate risk of wind disasters, which are suitable for the development of facility agriculture.
The strategic goal of “peaking carbon emissions and achieving carbon neutrality” shows China's responsibility as a major country to address global climate change issue, and its commitment to realizing a community of shared future for mankind and accelerating the course of energy-saving and emission-reduction. This study took a project with a daily output of 20,000 cubic meters of biogas as a case and used the method of life cycle assessment (LCA) to evaluate its environmental impact. The study divided the entire life cycle into three stages: raw material collection and pretreatment, medium-high temperature anaerobic fermentation and biogas resource utilization, and established an evaluation list for the biogas anaerobic fermentation project. The results show that the net production capacity of this biogas project can reach 2494064.6 kg/a. Compared with traditional coal power generation, its ability to reduce environmental impact is 234.9038 kpt/a, and the reduction rate is 32.89%. The study proves that the biogas project has productivity benefits and environmental benefits. Based on the current development situation of the biogas industry at home and abroad, and the opportunities and challenges under the vision of “peaking carbon emissions and achieving carbon neutrality”, this study shows that China's future biogas industry has great potential for development.
Guided by the theories of the Internet of Things, cloud computing, artificial intelligence and auto-control, we comprehensively utilized the methods and technologies of computer, geographic information and service-oriented sciences, to design a control terminal system, which included pump room control terminal, field control terminal, weather station monitoring terminal and moisture monitoring terminal, and constructed an intelligent irrigation cloud service system based on weather. The irrigation scheme would be generated according to the mathematical model of irrigation decision-making based on soil moisture and meteorological elements, and the intelligent irrigation cloud service system would distribute it to the water fertilizer integration equipment, thus realizing the whole chain management of irrigation and fertilization from scientific decision-making to accurate implementation. The result shows that the intelligent irrigation equipment with integrated water and fertilizer can achieve 36.36% water-saving rate, 26.17% fertilizer saving rate, 16.67% yield increasing rate and 13% increase in the proportion of high-quality apples, which has great popularization and application value.
Root vegetable crops, such as beet, potato, etc., are rich in nutrition and suitable for large-scale planting, and have broad development potential. However, the growth process of the aboveground and the underground parts of root vegetable crops differ widely. It is hard to estimate the growth of the underground tuber by observing the aboveground part. To monitor the process of the underground tuber growth in real time and conduct auto-management, a tuber auto-measuring device was developed. The device was composed of X-type measuring clamps, resistance displacement meters, built-in wires, data memories, and other components. A field test was conducted to measure sugar beet tuber growth by the device. The results showed that the device was capable of monitoring the tuber growth in real time, and was qualified to distinguish the growth period and determine the tuber root diameter. The error range of the developed device was 2%-7% through the investigation.
Environmental DNA metabarcoding (eDNA metabarcoding) is a fast, efficient and environmentally friendly method to investigate the diversity of fish species, but its sensitivity and reliability remain to be further evaluated. In this study, Gaobi Stream and Chengping Reservoir, located in the source region of Songyin Stream, a first level tributary of Oujiang River, were selected as the investigated waters, and the survey on fish species distributed in those two waters was carried out by traditional capture-based method and eDNA metabarcoding technology, respectively. The results showed that a total of 24 species of fish were found in the two waters by capture-based method, 88% (21 species) of fish species were recorded in the Oujiang River system. 12 fish species belonging to 4 orders, 8 families, and 11 genera were collected from Gaobi River, and 16 species of fish belonging to 3 orders, 4 families and 14 genera were collected from Chengping Reservoir. A total of 31 species were detected in the two waters by eDNA metabarcoding technology, and 84% (26 species) of fish species were recorded in the Oujiang River system. 28 fish species were found in Gaobi Stream, belonging to 5 orders, 12 families and 25 genera, and 27 species were found in Chengping Reservoir, belonging to 6 orders, 11 families, and 25 genera. However, the two survey methods found only one fish species together in the stream water and only five in the reservoir water. In addition, Shannon diversity index, Simpson diversity index, Margalef’s richness index and Pielou’s evenness of Gaobi Sream were higher than those of Chengping Reservoir, and the conclusions of the two survey methods were relatively consistent. In conclusion, eDNA metabarcoding can find more species and has higher sensitivity than the traditional method, but its results of fish species composition have a marked deviation from those of actual capture. Therefore, eDNA metabarcoding technology can only be used as reference for traditional fishery survey methods at present, and it is necessary to be cautious in drawing survey conclusions by using this technology.
Agricultural and forestry waste is a valuable biomass resource. If the resource cannot be used efficiently, it will cause serious environmental pollution and even great harm to human health. Therefore, the resource utilization of agricultural and forestry wastes is the important content of controlling agricultural non-point source pollution, saving biomass resources, energy conservation and emission reduction, protecting the ecological environment, achieving the goal of peaking carbon emissions and carbon neutralization, and social and economic sustainable development. In order to promote the resource utilization of agricultural and forestry wastes, this paper summarized the progress achieved in this field at home and abroad in recent years.
Water-retaining agent, also known as superabsorbent polymer, has the ability of absorbing water and controlling the release of fertilizer, and can promote the growth of plants. Water-retaining agents can be synthesized from synthetic polymers, natural polymers, and combinations of organic and inorganic materials. The synthesis of water-retaining agent includes physical, chemical and hybrid bonding, which is mainly realized by bulk polymerization, solution polymerization, inverse suspension polymerization, radiation polymerization and other methods. Based on this, the basic concept, properties, mechanism of action, synthesis methods and classification of water-retaining agents are reviewed, and some existing problems are also discussed in this paper. It is pointed out that the future research focus of water-retaining agent should be on high salt resistance, reusable property and mass production potential.
Agricultural Engineering
