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Sapindus mukorossi seeds are commonly drilled and processed into Buddha beads and other craft products. To improve the machining qualities of the micro-drilling of S. mukorossi seeds, the effects of drilling parameters (feed rate, drilling speed, and drill diameter) on the drilling force, hole diameter and hole morphology were found. The mechanism behind these changes was further analyzed. The drilling parameters and machining process for the micro-drilling of S. mukorossi seeds were optimized. Results indicated that each drilling parameter influenced the drilling force and hole-machining quality by affecting the amount of cutting, the working conditions of the drill bit, chip formation, and the generation of drilling heat. Moreover, the feed rate and drill diameter were the main factors that influenced the drilling force, and the drilling speed played a leading role that influenced hole-machining quality. Interestingly, for the drilling of S. mukorossi seeds, a feed rate of 0.03 mm/r, a drilling speed of 6 m/min, and a drill-bit diameter of 0.9 or 1.5 mm resulted in a hole with high accuracy, good hole morphology, and minimal wear on the drill bit. This study facilitates the selection of suitable drilling parameters and processing technology for the micro-drilling of S. mukorossi seeds to improve processing accuracies and qualities, and provides a theoretical basis for the improvement of related drilling processing equipment.

Forest fires have long been a significant global problem. How to reliably accomplish the early warning and real-time monitoring of forest fires has become a pressing issue in order to limit the damage caused by forest fires. A novel technological approach for forest fire monitoring has been made possible by the quick development of wireless sensor network (WSN) technology. Currently, batteries are the primary source of power for WSNs used in forests, but frequent battery replacement will compromise the network for monitoring. As a result, the power supply is the key limit to its application in forest areas. This paper puts forward the thermoelectric conversion based on the Seebeck effect. Its notable feature is to convert heat energy into electric energy through the temperature difference between shallow soil and air. In the process of testing the device, the maximum voltage was 803.36 mV. At the same time, a power management system (PMS) for a thermoelectric conversion device was designed. The main feature of this system is that there is no need for an external control module. In the laboratory test, the minimum input power of this system was 200 mV. When the load resistance was 8 KΩ, the output power was 0.55 mW, and the maximum efficiency could reach 65.38% when the input was 500 mV, which fulfills the requirements of low cost and high reliability, providing a feasible solution for solving the energy limitation problem of WSNs in a forest area.

Vibration harvesting is a promising method for walnut production owing to its low cost and high efficiency. However, current research focuses on simulation analysis and lacks a theoretical model explaining the walnuts’ specific vibration response. This affects the design of the input vibration parameters during harvesting and thus reduces the harvesting efficiency. In this paper, a novel theoretical model of walnuts during vibration harvesting was established to analyze the vibration response, including the motion morphology (motion trajectory and dropping position) and detachment force. A field test was then carried out to verify the theoretical model. The theoretical and experimental results showed that the motion trajectory of the walnuts during vibration harvesting is similar to an ellipse, and the dropping position is at either of the two end points of the trajectory. The detachment force was found to be proportional to the vibration amplitude and the square of the vibration frequency theoretically. This paper provides a theoretical reference for designing the optimal input vibration parameters of a harvesting device to improve the harvesting rate of walnuts.

A friction-driven forestry electric monorail car based on a wheel hub motor is designed with the aim of solving the problems of the low transportation capacity, low running speed, large turning radius, and poor stability of low-slope mountain forestry monorails. The relationships between the minimum turning radius and the steering spring elasticity coefficient, between the body tilt and the anti-tip spring elasticity coefficient, and between the minimum turning radius of the monorail car and the distance between the two chassis and the two steering wheels was provided by the theoretical calculation and analysis of the key parameters of a dual-chassis structure, steering device, and anti-tip device. The dimensional parameters of the key components were determined. The three-dimensional design of the overall car was carried out, and the feasibility of the design was verified in kinematic simulation experiments. A performance test of the monorail car was conducted with the minimum turning radius, maximum load capacity, maximum full load speed, climbing degree, and center of gravity offset as indicators. The test results show that the monorail car has a minimum turning radius of 3.3 m, a maximum load capacity of 300 kg, a maximum speed of 20 km·h−1 fully loaded, a maximum gradient of 21°, and a unilateral vibration amplitude of 8 mm or less. The double-chassis structure and anti-tip device met the design requirements. The good transportation performance of the designed monorail car effectively solves the problems of a large turning radius and unstable driving of current forestry monorails. Additionally, the designed monorail car is environmentally friendly and efficient, meeting the requirements of monorail transporters for low-slope mountain forests and laying the foundation for the intelligent harvesting and transportation of mountain forest fruits.

Walnuts with their shells are a popular agricultural product in China. However, mildew from growth can sometimes be processed into foods. It is difficult to visually determine which walnuts have mildew without breaking the shells. A non-destructive method for detecting walnuts with mildew was studied by combining spectral data with image information. A total of 120 “Lüling” walnuts with shells were used for the mildew experiment. The characteristics of the spectral data from six surfaces of all samples were collected in the range of 370–1042 nm on days 0, 15, and 30. The spectrum was pretreated using SNV, and the feature bands were extracted using PCA and modeled using a support vector machine (SVM). The results show that the overall classification accuracy was 93%, with an of accuracy of 100% for INEN walnuts (normal internally and externally). The accuracy for IMEM walnuts (mildew internally and externally) reached 87.29%. There was an accuracy of 78.6% for IMEN walnuts (mildew internally and normal externally). The non-destructive detection of mildewed walnuts can be undertaken using hyperspectral imaging technology, which provides a new technique for exploring the mechanisms of walnuts with mildew.

Aiming to reduce thermal energy loss at the cold side of a thermoelectric generator (TEG) module during thermoelectric conversion, a thermoelectric energy conversion system for heat recovery with a water-cooling energy exchange circuit was devised. The water-cooling energy exchange circuit realized sufficient recovery and reuse of heat accumulated at the cold side of the TEG, reduced the danger of heat accumulation, improved the stability and output capacity of thermoelectric conversion, and provided a low-cost and high-yield energy conversion strategy in energy conversion and utilization. Through the control variable method to adjust the heat generation of the heat source in the thermoelectric conversion, critical parameters (e.g., inner resistance of the TEG, temperatures of thermoelectric modules, temperature differences, output current, voltage, power, and efficiency of thermoelectric conversion) were analyzed and discussed. After using the control variable method to change the ratio of load resistance and internal resistance, the impacts of the ratio of load resistance to inner resistance of the TEG on the entire energy conversion process were elaborated. The results showed that the maximum value of output reached 397.47 mV with a current of 105.56 mA, power of 41.96 mW, and energy conversion efficiency of 1.16%. The power density of the TEG module is 26.225 W/m2. The stability and practicality of the system with a water-cooling energy exchange circuit were demonstrated, providing an effective strategy for the recovery and utilization of heat energy loss in the thermoelectric conversion process.

For the purpose of collecting solar radiation for energy conversion and utilization and improving the output performance of thermoelectric power-generation components, a new solar thermoelectric conversion device based on an all-glass solar heat transfer pipe and gravity-assisted heat pipe with recycling air cooling and water cooling circuits is designed. The uniqueness of the device lies in the combination of gravity-assisted heat pipes with excellent thermal conductivity and a direct air-cooled mode, a fin-cooled mode, and two solar-driven water-cooling modes with different flow rates. Based on the structure, the device can realize four separate output modes and multiple composite output modes and has practical significance for meeting different load power requirements, such as wireless sensors and electronics. Under a state of regular illumination from 3.14 × 104 lx to 10.04 × 104 lx, with one thermoelectric power generator (TEG) in one mode, the peak output voltage and power values of the device in single-output mode range from 183.1 mV to 370.7 mV and 33.5 mW to 137.2 mW, respectively, proving the feasibility of the proposed device. The energy supply of the above structure is completely obtained from the natural environment, and this aspect provides a high reference value for the cross-research of natural environment energy utilization and thermoelectric energy-conversion technology.

A two-phase closed thermosyphon is an efficient heat transfer element. The heat transfer process of this type of thermosyphon includes conduction and convective heat transfer accompanied by phase changes. Variations in the inclination angle of a thermosyphon affect the steady-state heat transfer performance of the device. Therefore, the inclination angle is an important factor affecting the performance of a thermosyphon. In this paper, an equation for the actual heating area variations with respect to the inclination angle is deduced, and a model for the areal thermal resistance of a thermosyphon is proposed by analyzing the main influence mechanisms of the inclination angle on the heat transfer process. The experimental results show that the areal thermal resistance, which accounts for the effect of the actual heating area, does not change with respect to the inclination angle and exhibits a linear relationship with the heat transfer rate. The thermal resistance equation is fit according to the experimental data when the inclination angle of the thermosyphon is vertically oriented (90°), and the predicted values of the thermosyphon’s thermal resistance are obtained when the thermosyphon is inclined. The deviations between the experimental data and predicted values are less than ±0.05. Therefore, the theoretical equation can accurately predict the thermosyphon’s thermal resistance at different inclination angles.

To efficiently harvest environmental micro-energy from shallow soil, simulated analysis, theoretical arithmetic and experimental verification are performed to explore the spatiotemporal rules of heat transfer on a soil/finned tube interface. Simulations are carried out for 36 types of different working conditions, and the empirical formulas for temperature and heat flux are obtained. The temperature and heat flux can be calculated using the formulas if the soil temperature, soil moisture content and finned tube initial temperature are known. The simulations also show that the highest heat flux can reach approximately 0.30 mW/mm2, and approximately 1507.96 mW of energy can be harvested through the finned tube. Theoretical arithmetic indicates that the heat transfer rate of the copper finned tube is 76.77% higher than that of the bare tube, the highest rate obtained in any study to date. Results also show that the finned tube should be placed where the soil moisture is greater than 30% to get more heat from the soil. A field experiment is carried out in the city of Harbin in Northeast China, where a thermoelectric power generation device has been installed and temperature data have been monitored for a certain time. The results are in good agreement with those obtained from the simulation analysis. The heat transfer processes and heat transfer steady state on the soil/finned tube interface are revealed in this work and are of great importance for the use of geothermal energy.