This paper focuses on obtaining fundamental data for optimizing the design of intelligent equipment for cutting natural rubber and its key components. It uses natural rubber bark as the research subject and employs specific experimental apparatus to measure the physical properties and contact coefficients of the rubber bark. The discrete element method, along with the Hertz–Mindlin model featuring bonding contacts, are employed to create a discrete element model of natural rubber bark. Parameters are calibrated, and model validation is performed. Subsequently, a one-factor simulation test is conducted to assess various cutting angles of the rubber cutter knife. A secondary Fourier fitting is applied to fit the curve to the average shear force values obtained from the simulation. The results indicate that the lowest average shear force, at 84.345 N, occurs within the range of cutting angles between 25° and 30°. The corresponding optimal cutting angle is 29.294°, suggesting that cutting with low resistance can be achieved at this angle, leading to reduced power consumption. Following a statistical analysis of field rubber-cutting tests conducted in a forest setting, it was found that the average power consumption for rubber-cutting operations under the optimal cutting angle is 0.96 W·h. Additionally, the volume of rubber discharged in the initial 5 min period is 6.53 mL. These findings hold significant importance for guiding the optimization and enhancement of the design of intelligent equipment for cutting natural rubber and its key components.

This study investigated the effect of the angle between the blade and the inclined disc on particle trajectory correction during ejection from an organic fertilizer side-throwing device. Using the inclined disc device as the test subject, a blade-based coordinate system was established to model the complex relative particle motion under combined disc and blade inclination. Particle dynamics and blade forces were analyzed quadrantally, enabling the development of a mechanical model and the derivation of displacement equations. Numerical simulation, virtual simulation, and experimental testing yielded the following results: Under the current device parameters, the relative velocity between particles and the blade reaches its maximum when the angle between the blade and the inclined disc is 80°. Within the angle range from 65° to 85°, as the angle increases, the scattering angle of single-sided discs monotonically decreases, while that of dual-sided discs monotonously increases. At an angle of 65°, the trajectories of the dual-sided disc flows tend to converge. At 80°, the flow is at the critical point between convergence and divergence. The effective throwing distance first increases and then decreases, reaching a maximum at an angle of 80°. This study clarifies the relationship between the angle correction of blade–disc inclination and particle velocity and trajectory on the blade, providing a reliable mathematical model and simulation method for similar studies in the field of inclined disc centrifugal material ejection.

It is the flourishing development of MOOCs that brings new mode of educa-tion. The paper focuses on the improvement of the teaching methods of pro-gramming experiment course in the environment of MOOCs, the develop-ment of experimental platform for innovative teaching methods, and the as-sessment methods of student learning. The current research and use of MOOCs are discussed, and its application in the programming experiment course. According to the present research analysis, the online programming experiment course platform is built, and a kind of online assessment system for students' achievement evaluation methods is elaborated. The academic performance and interest in learning are improved when experiment course platform is applied through two years teaching comparison. It is feasible to adopt the online platform for programming experiment course.

Research and test of the measurement sensing device for the downforce of no-till planter row unit gauge wheels

Aiming at a series of hot issues and topics, such as resource waste, environmental pollution, and Mollisol protection, related to the arbitrary discharge of livestock and poultry feces, livestock and poultry feces are taken as the research object, a questionnaire survey was conducted to investigate residents' cognition and willingness to pay (WTP) for the nonmarket value of livestock and poultry feces returning to farmland in Heilongjiang Province, China. The contingent valuation method (CVM) was used for the correlation analysis of WTP and socioeconomic characteristics, and correlation analysis of payment mode and socioeconomic characteristics. Meanwhile, the factors influencing WTP and payment mode were analyzed. The results show that the majority of the respondents are aware of the harmfulness of the arbitrary discharge of livestock and poultry feces and the importance of its nonmarket regeneration value. Approximately 90.09% of respondents were willing to pay for the return of livestock and poultry feces to fields. In 2020, the total value of WTP of livestock and poultry feces returning to farmland in Heilongjiang Province was 4.65 billion CNY, equivalent to 1.32% of the total agricultural production of Heilongjiang Province in the same year. And the nonmarket value of livestock and poultry feces is estimated to be 1456.69 CNY/t. The annual average WTP of rural and urban households is 286.42 CNY and 422.90 CNY per household, accounting for 0.46% and 0.52% of the average annual income of households, respectively. Therefore, the return of livestock and poultry feces to farmland utilization has a high nonmarket value. The analysis shows that the average annual household income is a significant factor in WTP, and the registered permanent residence type and the average annual household income are significant factors in payment mode. The research results should provide a scientific and theoretical basis for the government's policy and decision-making on the return of livestock and poultry feces to farmland. Keywords: nonmarket value, livestock and poultry feces, farmland utilization, CVM, WTP DOI: 10.25165/j.ijabe.20231602.7588 Citation: Shang J J, Xie Y T, Guo L F, Fan J X, Liu H X. Evaluation of the nonmarket value of livestock and poultry feces returning to farmland utilization using CVM in Heilongjiang, China. Int J Agric & Biol Eng, 2023; 16(2): 48-56.