Passive particles driven by self-propelled particle:The wake effect

This work focuses on numerically studying hydrodynamic interaction between a passive particle and a self-propelled particle,termed a squirmer,by using a two-dimensional lattice Boltzmann method(LBM).It is found that the squirmer can capture a passive particle and propel it simultaneously,provided the passive particle is situated within the squirmer's wake.Our research shows that the critical capture distance,which determines whether the particle is captured,primarily depends on the intensity of the squirmer's dipolarity.The stronger dipolarity of squirmer results in an increased critical capture distance.Conversely,the Reynolds number is found to have minimal influence on this interaction.Interestingly,the passive particle,when driven by the squirmer's wake,contributes to a reduction in the squirmer's drag.This results in a mutual acceleration for both particles.Our findings can provide valuable perspectives for formulating the principles of reducing the drag of micro-swimmers and help to achieve the goal of using micro-swimmers to transport goods without physical tethers.

MiR-30a-5p alleviates LPS-induced HPMEC injury through regulation of autophagy via Beclin-1

Background:Sepsis,a type of systemic disease,can impact nearly all organs,tissues and cells.Among them,endothelial cells are amongst thefirst to be affected and respond to the insult.In this study,we investigated the protective effects of microRNA-30a-5p(miR-30a-5p)on human pulmonary microvascular endothelial cells(HPMECs)treated with lipolysaccharide(LPS).Methods:An in vitro model of sepsis was established in HPMECs with the use of LPS.Transfecting with different tools(mimetic and inhibitor)to modify miR-30a-5p expression.Cell viability,proliferation and apoptosis were detected by the CCK-8 assay,the EdU kit andfluorescence staining,respectively.The autophagy-related protein and mRNA expression,the number of autophagosomes were separately examined through Western blot analysis,qPT-PCR and confocal microscopy.TargetScan and the luciferase reporter assays were used to probe target genes interacting with miR-30a-5p.Results:LPS caused a reduction in the viability and proliferation of HPMECs,as well as an elevation in the number of apoptotic cells.Subsequently,we observed that miR-30a-5p might play a role in preventing LPS-induced inhibition of cell damage and decreasing HPMEC apoptosis,suggesting the potential function of miR-30a-5p in this injury process.Finally,we confirmed that miR-30a-5p exerts its protective effect by regulating cell autophagy,possibly by targeting Beclin-1.Conclusion:Our study provided evidence that autophagy is a crucial aspect in the protective role of miR-30a-5p against LPS-induced HPMEC injury,identifying a promising target for sepsis-related endothelial cell injury.

A Double Adaptive Random Spare Reinforced Sine Cosine Algorithm

Many complex optimization problems in the real world can easily fall into local optimality and fail to find the optimal solution,so more new techniques and methods are needed to solve such challenges.Metaheuristic algorithms have received a lot of attention in recent years because of their efficient performance and simple structure.Sine Cosine Algorithm(SCA)is a recent Metaheuristic algorithm that is based on two trigonometric functions Sine&Cosine.However,like all other metaheuristic algorithms,SCA has a slow convergence and may fail in sub-optimal regions.In this study,an enhanced version of SCA named RDSCA is suggested that depends on two techniques:random spare/replacement and double adaptive weight.The first technique is employed in SCA to speed the convergence whereas the second method is used to enhance exploratory searching capabilities.To evaluate RDSCA,30 functions from CEC 2017 and 4 real-world engineering problems are used.Moreover,a nonparametric test called Wilcoxon signed-rank is carried out at 5%level to evaluate the significance of the obtained results between RDSCA and the other 5 variants of SCA.The results show that RDSCA has competitive results with other metaheuristics algorithms.

Establishing nursing adverse events’reporting content of hospital:using the Delphi method

Objective:To develop nursing adverse events’reporting content of hospital.Methods:The study included two phases.The first phase was to develop the category and definition of nursing adverse events that need to be reported through an expert meeting.The second phase was to develop every nursing adverse event’s reporting content by using the Delphi method.In total,8 experts attended the meeting and 15 experts conducted two rounds of consultation letter.Results:Nursing adverse events that need to be reported of hospital include pressure sore,fall/falling from bed,unplanned extubation,medication error,and accident.Reporting content of these events in detail had also been obtained,which was helpful for cause analysis systematically.Conclusions:The reporting content of the nursing adverse event of hospital is established,and it is a basis for further study of the development of nursing adverse event reporting and feedback system.

Design and experimental study of the end-effector for broccoli harvesting

The end-effector is an important part of the broccoli harvesting robot.Aiming at the physical characteristics of a large broccoli head and thick stem,a spherical cutting tool broccoli harvesting end-effector was designed in this study.First,the physical characteristics of broccoli were tested,and physical parameters such as the broccoli head diameter and stem diameter of broccoli were measured.The maximum cutting force of broccoli stems under different cutting angles was tested.Second,according to the physical characteristics and harvesting process of broccoli,the end-effector was designed,and the mathematical model of kinematics and dynamics was established.Based on the results of dynamic analysis,the end-effector rod was optimized,and the unilateral width of the slider was 40 mm,the length of the connecting rod was 120 mm,and the length of the crank was 42 mm.The mechanism needed an external driving force of 140.54 N to cut the broccoli stem.Therefore,a 32 mm cylinder with a load rate of 50%was selected as the power source.Finally,the feasibility of the broccoli harvesting end-effector was verified by the harvesting test.Experiments showed that the overall harvesting success rate of the end-effector is 93.3%,and the smoothness rate of the stem section is 83.3%.The harvesting performance of the broccoli end-effector was verified.This lays a foundation for agricultural robots to harvest broccoli.

An epidermal electrode based triboelectric walking energy harvester for wearable wireless sensing applications

Harvesting bio-kinetic energy using a triboelectric nanogenerator(TENG) is one of the promising routes to solve the sustainable energy supply problem for wearable electronics. However, additional materials, complex fabricating processes or specific mechanical structures are needed for existing TENGs to harvest bio-kinetic energy. Besides, they need to be tightly attached to the human body, which may result in detachment and malfunction under tense human motion. Herein, an intrinsic epidermal electrode-based TENG(E-TENG) is proposed to harvest human walking energy. The wearing shoes and ground are used as tribo-materials, and the human epidermis is used as the back electrode of the E-TENG. Compared with the traditional TENGs,the E-TENG does not need any additional tribo-materials and complex mechanical structures. Under optimal conditions, the voltage output of E-TENG can reach 914 V. E-TENG has been used as a self-powered warning sensor and pedometer sensor for demonstration. Furthermore, E-TENG based self-powered wireless sensor system has been developed using a newly designed micro energy electronic switch(MEES). Ambient ultraviolet intensity, temperature and humidity information can be monitored and then transmitted to mobile phone every 3.5 min, demonstrating great potential for widespread wearable applications.

Lightweight detection method for lotus seedpod in natural environment

In order to solve the problems of the current target detection algorithms,such as poor discrimination of occluded targets,multiple parameters,complex networks,large amounts of computation,and not conducive to the deployment of mobile terminals,a lightweight lotus seedpod detection method based on YOLOv5s model was proposed in this study.First,the dataset was augmented by using a combination of offline and online augmentation,which improved the adaptability and robustness of the model in complex environments.Then,a lightweight Ghost convolution module was introduced to replace the original convolution,and a lightweight bidirectional feature pyramid network was designed,which could enhance the feature extraction and fusion capability of the network and reduce the amount of calculation and model size;On this basis,the combination of WIoU loss function and Mish activation function was adopted to improve the accuracy of feature extraction.Finally,the knowledge distillation training strategy was used to ensure the proposed lightweight model has the learning ability of a complex network model,improving the recall and precision of model detection.The results of the ablation study show that the proposed method effectively improves the detection performance of the YOLOv5s model for lotus seedpods.The mean average precision of the improved model was 89.7%,compared with the original YOLOv5s model increased by 2.8%,and the parameters and FLOPs were reduced by 2.36M and 7.3G,respectively.Compared with other detection algorithm models,the proposed algorithm model has the advantages of less computation,smaller model size,and higher detection precision.Therefore,the proposed improved optimization method based on the YOLOv5s model can effectively detect lotus seedpods,which provides theoretical research and technical support for intelligent picking of lotus seedpods in the actual operating environment.

Edge preparation methods for cutting tools:a review

Edge preparation can remove cutting edge defects,such as burrs,chippings,and grinding marks,generated in the grinding process and improve the cutting performance and service life of tools.Various edge preparation methods have been proposed for different tool matrix materials,geometries,and application requirements.This study presents a scientific and systematic review of the development of tool edge preparation technology and provides ideas for its future development.First,typical edge characterization methods,which associate the microgeometric characteristics of the cutting edge with cutting performance,are briefly introduced.Then,edge preparation methods for cutting tools,in which materials at the cutting edge area are removed to decrease defects and obtain a suitable microgeometry of the cutting edge for machining,are discussed.New edge preparation methods are explored on the basis of existing processing technologies,and the principles,advantages,and limitations of these methods are systematically summarized and analyzed.Edge preparation methods are classified into two categories:mechanical processing methods and nontraditional processing methods.These methods are compared from the aspects of edge consistency,surface quality,efficiency,processing difficulty,machining cost,and general availability.In this manner,a more intuitive understanding of the characteristics can be gained.Finally,the future development direction of tool edge preparation technology is prospected.

Design of flower transplanting mechanisms based on double planet carrier non-circular gear train with complete rotation kinematic pair

In view of the problems of the existing mechanisms based on 2R open-chain planetary gear train for seedling transplanting,such as the bad tracking flexibility,low positioning accuracy,and high structure design difficulties of the mechanisms based on 3R open-chain planetary gear train for seedling manipulation.In this paper,a transplanting mechanism based on the solution domain synthesis of a 3R open-chain-based complete rotation kinematic pair,a gear train with a single cycle integral rotating pair,is designed.The Burmester curve equation is derived from the given transplanting trajectory and four exact poses corresponding to each other on the rotation center.Then,the open-chain road model of the 3R complete rotation kinematic pair is obtained under the constraint governed by the judgment condition of the hinge integral rotating pair.Meanwhile,combined with our developed in-house optimization software,the solution to the optimal parameters for the transplanting mechanism can be optimized according to the target trajectory.Finally,the feasibility of the design method is verified by transplanting testing,where kale seedlings with ages of about 20 d and heights of about 80-120 mm are used.The experimental results show that the actual motion trajectory of the prototype is basically identical to the theoretical trajectory,validating the feasibility of transplanting mechanism design,parts processing,and test-bed construction.Through the statistical analysis,the average success rate of transplanting is 90.625%,and the reliability of designed mechanism is satisfied.This study provides a promising solution for the seedling transplanting of two-planet scaffold pots.

Influence of impact velocity and impact attack angle of bullets on damage of human tissue surrogate--ballistic gelatin

Purpose Terminal performance of a bullet in human body is critical for the treatment of gunshot injury and optimization of bullet design.The effects of the impact velocity(v_(0))and the impact attack angle(δ_(0))of the bullet on its terminal performance was investigated,using a new evaluation method(called expansion method)based on the expansion of cracks and the permanent cavity wall in ballistic gelatin.Methods Ballistic gelatin was used to simulate human body.The 7.62 mm×39 mm rifle bullets with different v_(0)(600–76_(0)m/s)andδ_(0)(0°–6°)were fired into the gelatin blocks.The gelatin block was cut into slices of about 2_(0)mm thickness.The cracks and the permanent cavity on each slice were obtained manually.The damaged gelatin was determined using two methods:expanding the permanent cavity but ignoring the cracks,and expanding both the permanent cavity and the cracks.The relations between the damaged gelatin and v_(0)andδ_(0)were obtained using linear fitting method.Results According to the distribution of the damaged gelatin along the penetration depth,the damaged gelatin block could be divided into two parts:the less damaged part and the severely damaged part.The length of the less damaged part depends mostly onδ_(0);while the average damaged area of this part depends on bothδ_(0)as well as v_(0).The cracks contributed significantly to the total volume of damaged gelatin,particularly when the expansion was larger than 1.9 mm.The total damaged gelatin increases with v_(0),δ_(0)and the expansion extent.The average length of equivalent cracks grew with v_(0)andδ_(0)when considering the cracks,and decreased with v_(0)when ignoring the cracks.Conclusion The expansion method is suitable to investigate the influence of different factors of bullets on their terminal performance.The characteristics of the damaged gelatin have a linear relationship with the initial attack angle(δ_(0))and the initial velocity(v_(0))of the bullet.

An improved YOLOv3-tiny algorithm for vehicle detection in natural scenes

YOLO(You Only Look Once),as a target detection algorithm with good speed and precision,is widely used in the industry.In the process of driving,the vehicle image captured by the driving camera is detected and it extracts the license plate and the front part of the vehicle.Compared with the network structure of YOLOv3-tiny algorithm,the acquisition method of anchor box is improved by combining the Birch algorithm.In order to improve the real-time performance,the original two-scale detection is added to the multi-scale prediction of three-scale detection to ensure its accuracy.Finally,the experimental results show that the improved YOLOv3-tiny network structure proposed in this study can improve the performance of mean-average-precision,intersection over union and speed by 5.99%,17.52%and 48.4%,respectively,and the algorithm has certain robustness.

Fully self-powered instantaneous wireless liquid level sensor system based on triboelectric nanogenerator

Self-powered sensors are highly sought for wireless sensing applications in space exploration,industries,and environmental monitoring,etc.However,most current self-powered sensor technologies are based on the multiple energy conversion routine:energy collection,rectification,energy storage,and power management before it can be used for sensor systems,leading to exceptionally low energy utilization efficiency and very short periods of wireless sensing operation with majority of information lost.Here,we propose a triboelectric nanogenerator(TENG)based fully self-powered instantaneous and real-time wireless sensor system which does not contain electronic devices and microchips,but the passive components only.An innovative cylindrical capacitive-type liquid level sensor is also proposed and is then integrated into the wireless sensor system for monitoring liquid levels or identifying substance of the liquids.This sensor system can convert pulsed voltage output of the TENG into sinusoidal signal with a resonant frequency containing the sensing information and is transmitted to the receiver in distance in real-time.The maximum transmission distance of the sensor system could reach 1.5 m for a 10 cm diameter magnetic-core coil pair.The wireless sensor system exhibited excellent stability and excellent linearity with a sensitivity of 4.63 kHz/cm,and demonstrated its great application potential for the self-powered liquid level monitoring.

Spatial Clustering and Epidemiological Trends of Hand, Foot and Mouth Disease in China's Mainland,2009-2015

HFMD can be caused by a variety of enteroviruses,including Coxsackievirus A16 and enterovirus71.There are no effective therapeutic measures to cure HFMD at present.So,this study aimed to analyze the spatial relativity and the local accumulation type based on the theory of spatial analysis and the spatial autocorrelation analysis module of ArcGIS and Geo Da.We found that there was a seasonal trend in HFMD.The lowest incidence appeared in February,and the peak of the reported incidence was occurred during the period from May to June.However,in most cases,another peak appeared from September to November.The trend of incidence was related to age,too.The overall trend of the reported incidence was a U-shape in north-south orientation and exposed an inverted U-shape in east-west.The correlation between the spatial distribution of HFMD was positive.Hunan,Guangxi and Guangdong were the hot areas,while the cold spots were Jilin,Inner Mongolia,Xinjiang,Gansu and Qinghai.

Cutting edge preparation of microdrills by shear thickening polishing for improved hole quality in electronic PCBs

Printed circuit boards(PCBs)are representative composite materials,and their high-quality drilling machining remains a persistent challenge in the industry.The finishing of the cutting edge of a microdrill is crucial to drill performance in machining fine-quality holes with a prolonged tool life.The miniature size involving submicron scale geometric dimensions,a complex flute shape,and low fracture toughness makes the cutting edge of microdrills susceptible to breakage and has been the primary limiting factor in edge preparation for microdrills.In this study,a newly developed cutting edge preparation method for microdrills was tested experimentally on electronic printed circuit boards.The proposed method,namely,shear thickening polishing,limited the cutting edge burrs and chipping on the cutting edge,and this in turn transformed the cutting edge’s radius from being sharp to smooth.Moreover,the edge–edge radius could be regulated by adjusting the processing time.PCB drilling experiments were conducted to investigate the influence of different cutting edge radii on wear,hole position accuracy,nail head value,and hole wall roughness.The proposed approach showed 20%enhancement in hole position accuracy,33%reduction in the nail head value,and 19%reduction in hole wall roughness compared with the original microdrill.However,a threshold is needed;without it,excessive shear thickening polishing will result in a blunt edge,which may accelerate the wear of the microdrill.Wear was identified as the primary factor that reduced hole quality.The study indicates that in printed circuit board machining,microdrills should effectively eliminate grinding defects and maintain the sharpness of the cutting edge as much as possible to obtain excellent drilling quality.Overall,shear thickening polishing is a promising method for cutting edge preparation of microdrills.Further research and optimization can lead to additional improvements in microdrill performance and contribute to the continued advancement of printed circuit board manufacturing.