An improved YOLO v4 used for grape detection in unstructured environment

Visual recognition is the most critical function of a harvesting robot, and the accuracy of the harvesting action is based on the performance of visual recognition. However, unstructured environment, such as severe occlusion, fruits overlap, illumination changes, complex backgrounds, and even heavy fog weather, pose series of serious challenges to the detection accuracy of the recognition algorithm. Hence, this paper proposes an improved YOLO v4 model, called YOLO v4+, to cope with the challenges brought by unstructured environment. The output of each Resblock_body in the backbone is processed using a simple, parameterless attention mechanism for full dimensional refinement of extracted features. Further, in order to alleviate the problem of feature information loss, a multi scale feature fusion module with fusion weight and jump connection structure was pro-posed. In addition, the focal loss function is adopted and the hyperparameters α, γ are adjusted to 0.75 and 2. The experimental results show that the average precision of the YOLO v4+ model is 94.25% and the F1 score is 93%, which is 3.35% and 3% higher than the original YOLO v4 respectively. Compared with several state-of-the-art detection models, YOLO v4+ not only has the highest comprehensive ability, but also has better generalization ability. Selecting the corresponding augmentation method for specific working condition can greatly improve the model detection accuracy. Applying the proposed method to harvesting robots may enhance the applicability and robustness of the robotic system

S-phase kinase-associated protein 2 positively controls mitotic arrest deficient 2 in lung cancer cells

Background. Mitotic arrest deficient 2 (Mad2) is a key component of spindle assembly checkpoint and overexpressed in human lung cancers, but the mechanism of the deregulation of Mad2 in lung cancer is largely unknown. We aim to investigate the regulation of Mad2 by S-phase kinase-associated protein 2 (Skp2) in human lung cancer cells

Estimates of entropy numbers in probabilistic setting

In this paper, we define the entropy number in probabilistic setting and determine the exact order of entropy number of finite-dimensional space in probabilistic setting. Moreover, we also estimate the sharp order of entropy number of univariate Sobolev space in probabilistic setting by discretization method

Effect of Vacuum Packaging on Storage Quality of Peanut

The purpose of the study is to investigate the effect of vacuum packaging on storage quality of peanut. The acid value, peroxide value, relative conductivity, mildew rate and germination rate of peanut were examined in both vacuum-packed bags and control packaging bags. The results showed that the acid value, peroxide value, relative conductivity and mildew rate of peanut were maintained at a lower level and germination rate was maintained at a higher level in vacuum-packed bags than in control packaging bags. The storage quality of peanut in vacuum-packed bags was better than in control packaging bags. The order of different vacuum degree of vacuum-packed bags from good to bad according to storage quality of peanut was－0.06 MPa>－0.09 MPa>－0.03 MPa, and －0.06 MPa was the most beneficial vacuum degree for the peanut storage

Flexible Actuators Based on Conductive Polymer Ionogels and Their Electromechanical Modeling

High-performance flexible actuators, integral components of soft robotics, hold promise for advancing applications in safe human–robot interactions, healthcare, and various other fields. Notable among these actuators are flexible electrochemical systems, recognized for their merits in low-voltage manipulation, rapid response speed, and cost-effectiveness. However, the optimization of output strain, response speed, and stability presents a significant challenge in this domain. Despite the application of diverse electrochemically active materials to enhance actuation performance, a critical need persists for corresponding electrical-mechanical models to comprehensively grasp actuation mechanisms. In this study, we introduce a novel electrochemical actuator that utilizes conductive polymer ionogel as active electrodes. This ionogel exhibits exceptional properties, including high conductivity, flexibility, and electrochemical activity. Our electrochemical actuators exhibit noteworthy bending strain capabilities and rapid response rates, achieving frequencies up to 10 Hz at a modest voltage of 1 V. An analytical model integrating ion migration and dynamic processes has been established to elucidate actuator behavior. Simulation results highlight that electrodes characterized by low resistance and high capacitance are optimal for simultaneous enhancement of bending strain and blocking force. However, the augmentation of Young’s modulus, while increasing blocking force, compromises bending strain. Furthermore, a larger aspect ratio proves beneficial for unidirectional stress output, leading to increased bending strain, while actuator blocking force diminishes with greater length. These findings underscore the intricate interplay between material properties and dimensions in optimizing the performance of flexible electrochemical actuators. This work provides important practical and theoretical guidance for the manufacture of high-performance flexible actuators and the search for new smart materials

An Investigation of the Wear on Silicon Surface at High Humidity

Using an atomic force microscope (AFM), the wear of monocrystalline silicon (covered by a native oxide layer) at high humidity was investigated. The experimental results indicated that tribochemistry played an important role in the wear of the silicon at different relative humidity levels (RH = 60%, 90%). Since the tribochemical reactions were facilitated at 60% RH, the wear of silicon was serious and the friction force was around 1.58 μN under the given conditions. However, the tribochemical reactions were restrained when the wear pair was conducted at high humidity. As a result, the wear of silicon was very slight and the friction force decreased to 0.85 μN at 90% RH. The slight wear of silicon at high humidity was characterized by etching tests. It was demonstrated that the silicon sample surface was partly damaged and the native oxide layer on silicon sample surface had not been totally removed during the wear process. These results may help us optimize the tribological design of dynamic microelectromechanical systems working in humid conditions