Current Harvesting Research Articles

Continuing the continuous harvests of food production: from the perspective of the interrelationships among cultivated land quantity, quality, and grain yield

The rapid population growth around the world has become one of the main challenges for countries to ensure adequate food supply. To address this difficulty and ensure adequate food production, sustainable land use, in particular sustainable cultivated land (CL) use, can make a great contribution. Sustainable utilization of CL encompasses several aspects such as quantity and quality, but previous studies have focused on increasing food production, while the interrelationships among cultivated land quantity, quality, and grain yield (CLQQGY) have still received less attention. Hence, based on the GlobeLand30 data during 2000–2020, this paper analyzed the changes of CLQQGY in 130 prefecture-level cities in the Yangtze River Economic Belt (YREB) in China and explored whether the current consecutive harvests is sustainable in the future to feed increasing population. The results revealed the areal loss and quality degradation of CL in most cities in the YREB, the total CL area decreased by 31.07 × 104 hm2 and 282.59 × 104 hm2 during 2000–2010 and 2010–2020, respectively, and the CL quality declining trend was presented in 68.46% and 69.23% cities in the YREB during 2000–2010 and 2010–2020, respectively. Even with such acreage and ecological losses, the total grain yield still increased by 3.77% and 9.53% during 2000–2010 and 2010–2020, respectively, continuing the miracle “continuous harvests” of grain yield in this region. This successive increase in food production in the context of decreasing acreage and ecological deterioration of CL depend mainly on the amount of chemical fertilizer usage, the total power of agricultural machinery and rural electricity consumption. However, due to the heavy reliance on a growth model driven by resource inputs, this type of harvest appeared to be unsustainable because of the significant negative effects brought out by overusing resources. With a view to achieving sustainable use of CL and food production, therefore, this paper proposed policies to promote the sustainable use of CL and food supply for supporting the survival of increasing population through the full implementation of administrative regulations and economic measures that focus on the balance among the quantity and quality and food production of CL in the process of agricultural production and CL management.

Design and characteristic analysis of a high-performance deformable piezoelectric wind energy harvester based on coupled vibrations

The current vortex-induced vibration piezoelectric wind energy harvesters have a narrow operating wind speed range, while galloping piezoelectric energy harvesters are at risk of damage from excessive amplitude at high wind speeds, a novel high-performance deformable piezoelectric wind energy harvester based on coupled vibrations (DPWEH) has been proposed. The alteration of the compound blunt body shape effectively modifies the shedding characteristics and intensity of vortices, subsequently influencing the vibration mode and output voltage of the system. The vibration mode transitions from galloping to coupled vibration, ultimately to vortex-induced vibration. The rigid wing and long elastic beam suppress galloping at high wind speeds. A thinner flexible wing can extend the duration of coupled vibration. A smaller wing width ratio and larger Y-type base wing width are beneficial for increasing the output voltage. By optimizing the parameters of the compound blunt body, the onset wind speed can be effectively reduced, the effective wind speed bandwidth can be expanded, and the DPWEH can undergo coupled vibration for an extended duration while stably generating electricity. The peak output power is 0.36 mW at a load of 150 kΩ. Moreover, the energy harvester demonstrates the prolonged power generation capability of signal transmitters and 100 LED lights.

Improving On-farm Energy Use Efficiency by Optimizing Machinery Operations and Management: A Review

AbstractThe energy use and emissions from direct fossil fuel combustion on-farms to power farm machinery was critically reviewed. Approximately, 15% of agricultural production costs on-farm are energy-related. A potential solution to more sustainable energy use is a shift toward biofuels from renewable resources. The reduction of greenhouse gas emissions through the substitution of diesel oil with biodiesel depends on the feedstock, the inter-esterification process, the storage period, and ambient conditions. In modern tractors, increased fuel use efficiency (or reduced fuel consumption) has been achieved by power/load matching and the use of variable transmission. Engine management systems that are capable of continuously communicating with the engine and transmission to make appropriate adjustments based on inputs received from the tractor allow for quick and precise responses to changing conditions. As a result, maximum efficiency and productivity can be obtained from the tractor operating similarly to the traditional ‘gear-up and throttle-back’ methods of a proficient operator. The future for autonomous tractors is promising, though not new. Electric-powered tractors are near to commercialization or are already commercially available. Hybrid electric driven tractors present some advantages in terms of increased energy use efficiency and functionalities. Increased efficiency can lead to a reduction in diesel fuel consumption and hence, a concurrent decrease in CO2 emission. Where the local electricity supply has a low-carbon emission factor, this can also result in significant emission reductions. Small light-weight robotic equipment can potentially perform functions currently undertaken by tractor-drawn and other heavy equipment with high-fuel consumption, provided field operating capacity was not compromised. However, the size and weight limitations inherent in current harvesting and transport technology mean that soil compaction will still be a problem with robotic units. The robotic operation of medium-scale equipment within a precision-controlled traffic farming environment should offer more feasible and energy-efficient alternatives.

Structural Parameter Optimization of a Tomato Robotic Harvesting Arm: Considering Collision-Free Operation Requirements.

The current harvesting arms used in harvesting robots are developed based on standard products. Due to design constraints, they are unable to effectively avoid obstacles while harvesting tomatoes in tight spaces. To enhance the robot's capability in obstacle-avoidance picking of tomato bunches with various postures, this study proposes a geometric parameter optimization method for a 7 degree of freedom (DOF) robotic arm. This method ensures that the robot can reach a predetermined workspace with a more compact arm configuration. The optimal picking posture for the end-effector is determined by analyzing the spatial distribution of tomato bunches, the main stem position, and peduncle posture, enabling a quantitative description of the obstacle-avoidance workspace. The denavit-hartenberg (D-H) model of the harvesting arm and the expected collision-free workspace are set as constraints. The compactness of the arm and the accessibility of the harvesting space serve as the optimization objectives. The Non-dominated Sorting Genetic Algorithm II (NSGA-II) multi-objective genetic algorithm is employed to optimize the arm length, and the results were validated through a virtual experiment using workspace traversal. The results indicate that the optimized structure of the tomato harvesting arm is compact, with a reachability of 92.88% in the workspace, based on the collision-free harvesting criteria. This study offers a reference for structural parameter optimization of robotic arms specialized in fruit and vegetable harvesting.

An enhanced broadband piezoelectric energy harvester via elastic amplification structure for multidirectional vibration

Abstract Vibration energy harvesting using a piezoelectric mechanism has significant potential for powering wireless sensors. However, most current vibration energy harvesters face limitations such as bidirectionality, narrow bandwidth, and high operating frequencies. To address these issues, we propose an enhanced broadband piezoelectric energy harvester utilizing an elastic amplification structure for multidirectional vibration (EB-PVEH). By utilizing the multidirectional rotation capacity of the excitation block and the amplified foundation excitation provided by springs, the EB-PVEH effectively captures broadband vibrations in 2D space under low-frequency excitation. Additionally, its design features long-term durability, as the piezoelectric beams are smoothly excited by the pendulum-induced motion of the block without a tip mass. The practical feasibility and the impact of structural parameters on the output behavior of EB-PVEH were investigated through theoretical analysis and experimental testing. The results revealed that the introduction of springs dynamically amplified the harnessed electrical power output. Moreover, EB-PVEH could harvest the multidirectional vibration, and it exhibited different power-generating characteristics in various directions. Furthermore, the resonance frequency could be efficiently tuned by adjusting the flexible arm length and proof mass, with different optimal arm lengths identified for each vibration direction to maximize working bandwidth. The harvester achieved an optimal output power of 3.98 mW. Practical applications, such as charging a capacitor by driving an e-bike or a bike, demonstrate the potential of the proposed harvester to provide power for micro-electrical devices.

Modeling Ecological Niches And Sustainable Management Of Piper Guineense In Côte d'Ivoire For Conservation And Domestication

Background: Ecosystem degradation due to anthropogenic pressure is a major threat to biodiversity in Côte d'Ivoire. Piper guineense, a medicinal and aromatic plant, is particularly affected by overexploitation in the areas around the Taï and Azagny national parks. This study aims to model the ecological niches conducive to the domestication of P. guineense, to analyze current harvest levels and commercial dynamics. Materials and Method: Data on the presence and exploitation of Piper guineense in Côte d'Ivoire were collected from a literature review. The Maximum Entropy model was used to establish the ecological niche of the species and identify the most influential environmental variables. An ethnobotanical survey was conducted in the localities surrounding the Taï and Azagny national parks. Data on local dynamics around the exploitation of Piper guineense were collected. Results: Piper guineense is mainly present in the dense rainforests of southern Côte d'Ivoire, with a marked dependence on minimum and maximum rainfall. Ecological modeling indicates probable areas of presence in the studied parks, with an AUC of 0.822, demonstrating the robustness of the model. Furthermore, ethnobotanical surveys reveal that 55.79% of harvesters around Taï Park and 47.5% around Azagny Park are non-natives, suggesting a strong economic dependence of these populations on this resource. Reported harvests are more abundant around Taï Park (1968 kg) than Azagny (1274 kg). Conclusion: Domestication of P. guineense is proposed as a viable alternative to meet the growing demand, while reducing pressure on natural ecosystems. Conservation efforts will need to include awareness-raising initiatives, harvest quotas, and the introduction of agroforestry practices for sustainable management of this resource

A passive self-excited oscillation AC low-voltage energy harvesting circuit without a bridge

Most current electromagnetic energy harvesters use capacitor voltage multipliers or boost circuits controlled by external signals to step up and store energy. However, for most low-voltage output electromagnetic energy harvesters, generating switching control signals and rectification results in significant energy loss. To reduce these losses, this paper proposes an AC boost circuit without additional power supply or rectifier bridge, designed for low-voltage electromagnetic energy harvesting. Both theoretical analysis and experimental results confirm the effectiveness of the proposed interface. The results show that the circuit can start self-excited boosting at an initial voltage of 0.48V and achieve an AC-DC conversion efficiency of 71.3 % within an input voltage range of 0–2.9V.

The Devils in the Details—but So Are the Angels: Linear Density Estimates of Harpagophytum zeyheri (Devil's Claw) From the Zambezi Region, Namibia

ABSTRACTHarpagophytum zeyheri (devil's claw) tubers are manually harvested for its pharmaceutical properties (anti‐inflammatory) in the sandier regions, especially the communal areas in north‐eastern Namibia, with various authors having questioned the sustainability and viability of current harvesting practices. Although regulation in the form of a quota system is implemented, this is not based on scientifically established density estimates or sustainable harvesting quotas. There is a dearth of published data regarding density estimates for H. zeyheri from Namibia. The average linear density from the Zambezi Region (all areas; this study) is 22.4 plants/km while other estimates from Namibia for H. procumbens vary between < 1 and 2000 plants/ha. The aim of this study was to contribute to the poorly known distribution and density of H. zeyheri from the Zambezi Region where most of Namibia's resource for the export market originates from and to highlight the potential threat of not conducting scientifically based preharvest counts on sustainability of this valuable resource.

Horns, hunters, and harvest: re‐examining management paradigms for pronghorn

AbstractThe sustainable use of wildlife is foundational to the success of the North American model of wildlife conservation. Harvest management often is shaped through both species biology and public desires. The long timespan it takes males of most ungulate species to reach peak weapon size has created a situation in harvest management in which harvest strategies cannot prioritize both generous hunter opportunity and opportunities to pursue large‐weaponed males; therefore, current harvest paradigms prioritize one at the expense of the other. In contrast to other species, pronghorn (Antilocapra americana) attain the majority of their peak horn size early in life. The rapid development of horns relative to their age may allow for liberal harvest without sacrificing the opportunity for hunters to harvest males with large horns. We evaluated the influence of sex ratios and average age of harvested males on the average horn size of harvested male pronghorn from 2019 to 2022 in 9 hunt areas in Wyoming, USA. Although mean age of harvested males was negatively affected by rate of harvest, increases in mean age at harvest led to only slight increases in mean horn size (i.e., a 1‐year increase in mean age increased mean horn size by 2.1 cm [~1 inch]). The proportion of the harvest composed of large‐horned males was not influenced by mean age of harvest or sex ratio of the population. Based on simulated populations, increasing harvest led to an increase in the number of large‐weaponed pronghorn in the harvest—a relationship that existed for bighorn sheep (Ovis canadensis) and elk (Cervus canadensis) but only at low to moderate rates of harvest. The comparatively young age that pronghorn attain near‐peak horn size alleviates what is otherwise a tradeoff between hunter opportunity and managing for large horn size that is evident in management of other ungulate species. Though rarely a reality in management for large ungulates, for pronghorn, liberal harvest may be possible while still providing opportunity to harvest males with large horns.

Design and Testing of an Electric Side-Mounted Cabbage Harvester

To address the limitations of current cabbage harvesters in China, which are often designed for a single variety and lack adaptability to different cabbage varieties, we developed an electric side-mounted cabbage harvester suitable for field operations in the Jiangsu region of China. This design is informed by the statistical analysis of the physical and agronomic parameters of major cabbage varieties. The harvester consists of key components, including an extraction device, a leaf-stripping device, a clamping and conveying device, and a root-cutting device. Powered by a 120 Ah direct current (DC) power source, it is capable of performing cabbage extraction, feeding, clamping, conveying, root cutting, and boxing in a single operation for three hours. Through theoretical analysis of the key components, specific parameters were determined, and field tests were conducted to verify the design. The results of the field experiments indicate that all components of the cabbage harvester operated effectively. Optimal performance was observed when the extraction roller speed was set between 100 and 110 RPM, the conveyor belt speed at 60 RPM, and the cutter speed between 160 and 220 RPM, resulting in a low cabbage harvest loss rate. The harvest loss rates from the three experiments were 11.3%, 13.3%, and 12%, respectively, which meets the mechanical harvesting requirements for cabbage.

Harvest sustainability assessments need rethinking under climate change: A ringed seal case study from Svalbard, Norway

AbstractThroughout the Arctic, ice‐affiliated marine mammals constitute local subsistence resources but detrimental effects of declines in their sea ice habitats create a need for harvest sustainability assessments in light of climate change. At the same time, empirical data required for thorough population analysis of these species are often sparse at best, as illustrated by the focal species in this study, ringed seals in Svalbard: the last population survey took place two decades ago (2002–2003), demographic data are limited to age, sex, and reproductive status of a small subset of shot individuals, and harvest reporting is patchy and incomplete. Data sparsity is one of the main reasons why potential biological removal (PBR) became a commonly used tool for assessing sustainability of marine mammal harvests. Herein, we calculated PBR for Svalbard ringed seals using both recommended default parameters and population‐specific parameters obtained from an integrated population model (IPM). PBR estimates were highly uncertain, suggesting the number of sustainably harvestable individuals could lie anywhere between 0 and 91, with a substantial chance of any harvest being unsustainable under current environmental conditions and trends. Subsequent population viability analyses (PVAs) further confirmed that the current harvest was likely unsustainable, even in a scenario in which sea ice conditions would not deteriorate (and therefore lower pup survival) further. However, uncertainty in population projections was high, and forecasts thus not ideal for formulating management advice. Better forecasts will require more frequent population surveys and obtaining more knowledge regarding the links between vital rates and environmental conditions, both of which may be facilitated by the adoption of novel technology (e.g., drone monitoring, genetic studies). The modeling framework created in this study can be readily updated with new data as they become available, and can serve as a tool for adaptive management of this and other marine mammal populations.

Underwater blade-free triboelectric nanogenerator for harvesting current energy in low-speed current

Ocean current energy bears the characteristics of wide distribution and high energy density. Harvesting current energy as the in-situ power for distributed ocean sensors will greatly enhance the sustainability of ocean sensing. In many parts of the ocean, the current speed is not desirable (low or unstable) for conventional current energy harvesting devices. Here, an underwater blade-free triboelectric nanogenerator (UBF-TENG) is developed to effectively utilize the low-speed currents through the flow-induced vibration (FIV). The power generation unit is fully enclosed inside the shell, effectively reducing the direct impact and underwater corrosion. The study demonstrates that within the established experimental parameters space, the optimized UBF-TENG can facilitate a start-up speed as low as 0.14 m/s. The UBF-TENG has achieved a maximum open-circuit voltage output of 250 V and a maximum short-circuit current output of 2.2μA at 0.76 m/s. The charging capacity of the UBF-TENG is tested with various capacitors, demonstrating the application potential of the UBF-TENG as an in-situ power supply underwater.

Design and characterization of a wind-adaptable piezoelectric energy harvester utilizing a rigid-flexible compound blunt body

In response to the challenges posed by uncontrolled amplitude during galloping and narrow effective bandwidth during vortex-induced vibrations in current energy harvesters, a novel wind-adaptable piezoelectric energy harvester utilizing a rigid-flexible compound blunt body (W-APEH) is proposed. The rigid-flexible compound blunt body improves environmental adaptability and power generation capacity. During the transformation process of the rigid-flexible compound blunt body from a Y-shape to an r-shape, a vibration pattern changes from galloping to coupled vibration, then to vortex-induced vibration. The feasibility of the structure and principle of the W-APEH were proved through a series of simulations and experiments. The higher proportion of rigid wings within a blunt body increases the susceptibility to galloping. A larger windward angle will delay the occurrence of galloping in the W-APEH, shorten the time of coupled vibration, and reduce the output voltage. In the case of the flexible wing thickness remains below 0.3 mm, an increase in thickness leads to an extended galloping time, with vortex-induced vibrations occurring later. Specifically, the onset wind speed is only 3.5 m/s, and the working wind speed range is 5–21 m/s with appropriate structural dimensions. Furthermore, the W-APEH provides a maximum output power of 3.78 mW at an optimal load resistance of 250 kΩ.

Charge self-shuttling triboelectric nanogenerator based on wind-driven pump excitation for harvesting water wave energy

The most important ocean energy sources are wind energy and water wave energy, both of which are significant to carbon neutrality. Due to uneven distribution and random movement, the conversion efficiency from the two energies into electrical energy is limited, so the coupling of them is necessary. However, the current energy harvesting technologies generally target one certain type, or are simple mechanical coupling. Here, we propose a composite water wave energy harvesting scheme with wind excitation based on triboelectric nanogenerators (TENGs). A rotation TENG driven by wind is introduced as a pump to inject charges into the main TENG. For the main TENG driven by water waves, a specially designed charge self-shuttling mode is applied (CSS-TENG). Under the pump excitation, the shuttling charge amount is increased by 11.8 times, and the peak power density reaches 33.0 W m−3, with an average power density of 2.4 W m−3. Furthermore, the CSS-TENG is expanded into an array by parallel connection, and the practical applications are demonstrated. This work organically couples the wind and water wave energy in the ocean scene, through the charge pumping and self-shuttling mode, providing a new pathway for the synergistic development of clean and renewable energy sources.

Modeling population dynamics of beluga whales in the Eastern High Arctic – Baffin Bay population

AbstractBeluga whales (Delphinapterus leucas) have a long history of subsistence harvest that has continued into the present and a history of exploitation through commercial harvest. The Eastern High Arctic – Baffin Bay (EHA) population of beluga whales has the northernmost distribution of any beluga whale population in Canada. Beluga whales from the EHA population have a single complete abundance estimate from 1996 and 3 partial abundance estimates in 1981, 2010, and 2012 from aerial surveys; reliable estimates from surveys are lacking in recent years, limiting the ability to determine population dynamics. In 2020 satellite imagery was used to estimate abundance for beluga whales in the EHA population for estuaries in the whales' summering area. We built a stochastic stock production model to estimate population dynamics from the start of reliably compiled harvest history data in 1977 to 2022, using abundance estimates from 1981, 1996, 2010, 2012, and 2020. We also extended the model 10 years into the future under 7 potential annual harvest scenarios (within the range of annual reported harvests) to calculate the probability of decline. We estimated the starting population in 1977 as 29,615 whales (95% CI = 20,765–46,251), and the estimate from 2022 was 16,495 whales (95% CI = 6,731–33,504). Landed catch of 0, 100, 200, 300, 400, 500, and 600 beluga whales annually resulted in <1%, 3%, 23%, 50%, 70%, 83%, and 90% probabilities of decline, respectively. There was a notable decrease in abundance over the time series, likely caused by harvest pressure. Harvest in recent years has ranged from 155–553 catches per year, and our results suggest that 108 landed catches per year equates to a 5% risk of decline, the low risk goal for precautionary fisheries management, which aligns with population conservation goals. Our model is a first step in understanding the EHA beluga whale population dynamics using what data are available and suggests that current harvests in some years may result in a population decline and should be monitored.

Multi-Variable Optimization to Enhance the Performance of a Cantilevered Piezoelectric Harvester

Over the past decade, various researchers have shown the practicality of extracting electrical energy from vibrating structures. The primary objective of this research was to optimize the parameters of a basic cantilever harvester to maximize the energy production of electricity from surrounding mechanical energy. A distributed parameter model and its modal solution were utilized to determine the design variables via a parametric investigation. It is important to ensure sufficient power generation when there is a wide range of frequencies being excited, without any specific frequency being emphasized. The cost function for the optimization problem was defined as the average power within a specific frequency range, considering geometric and physical restrictions. It was discovered that different parameters’ values can be utilized to generate varying maximum power levels for different frequency ranges. Furthermore, a comparative analysis was performed between the finite element method (FEM) using ANSYS and the current harvesting model. The comparison demonstrated a high level of concordance, enabling the utilization of the finite element method (FEM) for subsequent investigation.

Tomato Recognition Method Based on the YOLOv8-Tomato Model in Complex Greenhouse Environments

Tomatoes are a critical economic crop. The realization of tomato harvesting automation is of great significance in solving the labor shortage and improving the efficiency of the current harvesting operation. Accurate recognition of fruits is the key to realizing automated harvesting. Harvesting fruit at optimum ripeness ensures the highest nutrient content, flavor and market value levels, thus maximizing economic benefits. Owing to foliage and non-target fruits obstructing target fruits, as well as the alteration in color due to light, there is currently a low recognition rate and missed detection. We take the greenhouse tomato as the object of research. This paper proposes a tomato recognition model based on the improved YOLOv8 architecture to adapt to detecting tomato fruits in complex situations. First, to improve the model’s sensitivity to local features, we introduced an LSKA (Large Separable Kernel Attention) attention mechanism to aggregate feature information from different locations for better feature extraction. Secondly, to provide a higher quality upsampling effect, the ultra-lightweight and efficient dynamic upsampler Dysample (an ultra-lightweight and efficient dynamic upsampler) replaced the traditional nearest neighbor interpolation methods, which improves the overall performance of YOLOv8. Subsequently, the Inner-IoU function replaced the original CIoU loss function to hasten bounding box regression and raise model detection performance. Finally, the model test comparison was conducted on the self-built dataset, and the test results show that the mAP0.5 of the YOLOv8-Tomato model reached 99.4% and the recall rate reached 99.0%, which exceeds the original YOLOv8 model detection effect. Compared with faster R-CNN, SSD, YOLOv3-tiny, YOLOv5, and YOLOv8 models, the average accuracy is 7.5%, 11.6%, 8.6%, 3.3%, and 0.6% higher, respectively. This study demonstrates the model’s capacity to efficiently and accurately recognize tomatoes in unstructured growing environments, providing a technical reference for automated tomato harvesting.

Bed-scale rockweed harvest findings are not altered by study critiques, a response to Seeley et al.

Seeley et al., 2024 (Comment: A reexamination of Johnston et al., 2023, bed-scale impact and recovery of a commercially important intertidal seaweed. J. Exp. Mar. Biol. Ecol. 574) describe a number of reasons that they believe our study's experimental design was flawed and our inferential conclusions were incorrect. We believe that these claims are the result of misunderstandings of the objectives behind our sampling design and statistical analyses. Throughout this response to Seeley et al., we reiterate key objectives of our study design: examining rockweed harvest at a whole-bed scale, realistically capturing the effects of current commercial rockweed harvest methods in Maine, and using coastwide site averages to estimate effect sizes of rockweed harvest. The first claim by Seeley et al. that our study design severely undersampled rockweed beds ignores established sampling methodologies in rockweed research. The suggestion that our sampling design resulted in impact sites that were de facto control sites is not supported by our analyses that showed greater declines in mean rockweed height and biomass at impact sites relative to control sites. In response to their second claim that rockweed companies had control of key elements of our study design and execution, we detail our specific approaches to lessen any possibility for such conflicts to bias our findings. In the final section of our response, we present power analyses in support of our Before-After Control-Impact study design and we highlight the statistically significant effects of treatment on rockweed biomass that contradict Seeley et al.'s claim that we drew conclusions about biomass recovery based solely on large p-values.

A piezoelectric cantilever-beam-spring-pendulum oscillator for multi-directional vibration energy harvesting

Harvesting energy from environmental vibrations holds significance for powering wireless sensors and transducers. However, the current vibration energy harvesting methods still have room for improvement, especially in the field of low-frequency vibration, where the performance of output voltage is relatively insufficient. This paper proposes a novel piezoelectric energy harvester consisting of a piezoelectric cantilever beam and a spring pendulum in order to address this challenge. Under external excitation, energy exchange is generated between the internal parts of the system, so that the swinging of the pendulum is interchanged with the extension and contraction motion of the spring and the bending motion of the cantilever beam to realize multidirectional energy harvesting. Firstly, the energy equation of system is obtained and the dynamics model of system is derived based on Lagrange's theorem. In addition, the response characteristics of system under harmonic excitation and the effects of different parameters on the system performance are investigated by simulation. With proper parameter selection, the system can produce higher output voltages. Compared to a piezoelectric cantilever-single-pendulum, the proposed structure demonstrates superior performance, especially in low-frequency vibration. The maximum voltage amplitudes in the x- and z-directions were 106.6% and 187.3% of those of the piezoelectric cantilever-single-pendulum, respectively. This paper proves the superior energy harvesting performance of the proposed structure.

A method for cabbage root posture recognition based on YOLOv5s

Efficient, non-destructive cabbage harvesting is crucial for preserving its flavor and quality. Current cabbage harvesting mainly relies on mechanized automatic picking methods. However, a notable deficiency in most existing cabbage harvesting devices is the absence of a root posture recognition system to promptly adjust the root posture, consequently impacting the accuracy of root cutting during harvesting. To address this issue, this study introduces a cabbage root posture recognition method that combines deep learning with traditional image processing algorithms. Preliminary detection of the main root Region of Interest (ROI) areas of the cabbage is carried out through the YOLOv5s deep learning model. Subsequently, traditional image processing methods, the Graham algorithm, and the method of calculating the minimum circumscribed rectangle are employed to specifically detect the inclination angle of cabbage roots. This approach effectively addresses the difficulty in calculating the inclination angle of roots caused by occlusion from outer leaves. The results demonstrate that the precision and recall of this method are 98.7 % and 98.6 %, respectively, with an average absolute error of 0.80° and an average relative error of 1.34 % in posture. Using this method as a reference for mechanical harvesting can effectively mitigate cabbage damage rates.