Calculation and Analysis of TVMS Considering Profile Shifts and Surface Wear Evolution Process of Spur Gear

Profile shift is a highly effective technique for optimizing the performance of spur gear transmission systems.However,tooth surface wear is inevitable during gear meshing due to inadequate lubrication and long-term operation.Both profile shift and tooth surface wear(TSW)can impact the meshing characteristics by altering the involute tooth profile.In this study,a tooth stiffness model of spur gears that incorporates profile shift,TSW,tooth deformation,tooth contact deformation,fillet-foundation deformation,and gear body structure coupling is established.This model efficiently and accurately determines the time-varying mesh stiffness(TVMS).Additionally,an improved wear depth prediction method for spur gears is developed,which takes into consideration the mutually prime teeth numbers and more accurately reflects actual gear meshing conditions.Results show that consideration of the mutual prime of teeth numbers will have a certain impact on the TSW process.Furthermore,the finite element method(FEM)is employed to accurately verify the values of TVMS and load sharing ratio(LSR)of profile-shifted gears and worn gears.This study quantitatively analyzes the effect of profile shift on the surface wear process,which suggests that gear profile shift can partially alleviate the negative effects of TSW.The contribution of this study provides valuable insights into the design and maintenance of spur gear systems.

Study of three-dimensional spatial diffuse discharge in contact electrode structure applied to air purification

In this work,based on the role of pre-ionization of the non-uniform electric field and its effect of reducing the collisional ionization coefficient,a diffuse dielectric barrier discharge plasma is formed in the open space outside the electrode structure at a lower voltage by constructing a three-dimensional non-uniform spatial electric field using a contact electrode structure.The air purification study is also carried out.Firstly,a contact electrode structure is constructed using a three-dimensional wire electrode.The distribution characteristics of the spatial electric field formed by this electrode structure are analyzed,and the effects of the non-uniform electric field and the different angles of the vertical wire on the generation of three-dimensional spatial diffuse discharge are investigated.Secondly,the copper foam contact electrode structure is constructed using copper foam material,and the effects of different mesh sizes on the electric field distribution are analyzed.The results show that as the mesh size of the copper foam becomes larger,a strong electric field region exists not only on the surface of the insulating layer,but also on the surface of the vertical wires inside the copper foam,i.e.,the strong electric field region shows a three-dimensional distribution.Besides,as the mesh size increases,the area of the vertical strong electric field also increases.However,the electric field strength on the surface of the insulating layer gradually decreases.Therefore,the appropriate mesh size can effectively increase the discharge area,which is conducive to improving the air purification efficiency.Finally,a highly permeable stacked electrode structure of multilayer wire-copper foam is designed.In combination with an ozone treatment catalyst,an air purification device is fabricated,and the air purification experiment is carried out.

YOLO-CRD:A Lightweight Model for the Detection of Rice Diseases in Natural Environments

Rice diseases can adversely affect both the yield and quality of rice crops,leading to the increased use of pesticides and environmental pollution.Accurate detection of rice diseases in natural environments is crucial for both operational efficiency and quality assurance.Deep learning-based disease identification technologies have shown promise in automatically discerning disease types.However,effectively extracting early disease features in natural environments remains a challenging problem.To address this issue,this study proposes the YOLO-CRD method.This research selected images of common rice diseases,primarily bakanae disease,bacterial brown spot,leaf rice fever,and dry tip nematode disease,from Tianjin Xiaozhan.The proposed YOLO-CRD model enhanced the YOLOv5s network architecture with a Convolutional Channel Attention Module,Spatial Pyramid Pooling Cross-Stage Partial Channel module,and Ghost module.The former module improves attention across image channels and spatial dimensions,the middle module enhances model generalization,and the latter module reduces model size.To validate the feasibility and robustness of this method,the detection model achieved the following metrics on the test set:mean average precision of 90.2%,accuracy of 90.4%,F1-score of 88.0,and GFLOPS of 18.4.for the specific diseases,the mean average precision scores were 85.8%for bakanae disease,93.5%for bacterial brown spot,94%for leaf rice fever,and 87.4%for dry tip nematode disease.Case studies and comparative analyses verified the effectiveness and superiority of the proposed method.These researchfind-ings can be applied to rice disease detection,laying the groundwork for the development of automated rice disease detection equipment.

Study of generation characteristics of glow-type atmospheric-pressure plasma jet based on DC discharge in air

In order to form an atmospheric-pressure plasma jet without airflow, a needle–ring electrode structure is proposed in this paper. When heteropolar potentials are applied to a needle and a ring, a marked electric field strength enhancement around the needle’s pointed end has been found. When the same potential is applied to both the needle and the ring, the lateral electric field strength for the needle can be weakened. By using the above two methods, an increase of the difference between the pointed end electric field strength and the lateral one is achieved and stable plasma jets are formed. A symmetrical space electric field distribution is established at the pointed end of the needles when several sets of heteropolar needle–ring electrodes are uniformly arranged, which is conducive to forming a uniform array plasma jet. Under DC discharge conditions, a safe and stable plasma jet of high density and an array plasma jet are successfully achieved.

Study of ionic wind based on dielectric barrier discharge of carbon fiber spiral electrode

Based on the idea that a large number of charged particles can be generated by a high-frequency alternating current(AC)dielectric barrier discharge(DBD),and charged particles can be accelerated directionally by a direct current(DC)electric field,a new type of ionic wind formation method is proposed in this paper.To this end,a carbon fiber spiral electrode serves as the generation electrode and a metal rod electrode as the collection electrode,with AC and DC potentials applied respectively to the generation electrode and the collection electrode to form an AC-DC coupled electric field.Under the action of the coupled electric field,a dielectric barrier discharge is formed on the carbon fiber spiral electrode,and the electrons generated by the discharge move from the generation electrode to the collection electrode in the opposite direction of the electric field vectors.During the movement,energy is transferred to the gas molecules by their colliding with neutral gas molecules,thereby forming a directional gas stream movement,i.e.ionic wind.In the research process,it is verified through electric field simulation analysis and discharge experiment that this method can effectively increase the number of charged particles in the discharge process,and the velocity of the ionic wind is nearly doubled.On this basis,the addition of a third electrode forms a distinct discharge region and an electron acceleration region,which further increases its velocity.The experimental result shows that the ionic wind speed reaches up to 2.98 m s^?1.Thanks to the ability of the electrode structure to generate an atmospheric pressure DBD plasma and form an ionic wind,we can create a noise-free air purification device without resorting to a fan,with this device having good application prospects in the field of air purification.

Generation characteristics of a metal ion plasma jet in vacuum discharge

To improve the performance of a metal ion plasma jet in vacuum discharge, an anode-insulated cone-cylinder electrode with insulating sleeve is proposed in this paper. Discharge characteristics and generation characteristics of plasma of the electrode are investigated, effects of diameter of insulating sleeve, variety of cathode material and length of the insulating sleeve on characteristics of metal ion plasma jet are discussed. Results indicate that a directional and steady plasma jet is formed by using the novel electrode with insulating sleeve under high vacuum conditions. Moreover, the properties of metal ion plasma jet are improved by using the aluminum cathode and thin and long insulating sleeve. The study provides strong support for research of vacuum metal ion plasma thruster and ion implantation technology.

First record of Ulva californica in the mainland of China:a single alien parthenogenetic population in discontinuous distribution

Molecular investigations have raised concerns about the ecological risks of green tides caused by alien Ulva species in new habitats.The green tide-forming species U.californica Wille was generally considered to be native to North America,but new records have been widely reported in Europe,Asia,and Oceania in recent decades,indicating a strong dispersal capacity of the species.In this study,the first record of U.californica on the coastline of China's Mainland was reported,following a combined identification with multi-molecular markers and morphological characterization.It was shown that this species has a discontinuous distribution pattern along the coast of China's Mainland,with northern populations in the Yellow Sea and southern populations in the East China Sea and South China Sea.According to results of examination for life cycles and identification with mating type(MT)genetic markers,it was indicated that all U.californica samples were male gametophytes,and reproduced themselves through parthenogenesis solely.Combined with the fact that southern and northern populations are highly genetically identical,here we believed that U.californica was a recent alien species to China's Mainland with a rapid local spread.This finding provided evidences that the ability to reproduce in a variety of ways may play an important role in the spread of Ulva species,as well as essential basic data for marine risk management of green tides in China.In addition,according to the phylogeographic analysis,the possible geographical origin and global dispersal routes of U.californica were also proposed.

Study on water treatment effect of dispersion discharge plasma based on flowing water film electrode

To improve the utilization rate of plasma active species,in this study,a closed non-uniform air gap is formed by a flowing water film electrode and a sawtooth insulating dielectric layer to realize the diffuse glow discharge in the atmosphere.Firstly,the electric field distribution characteristics of non-uniform air gap in the sawtooth dielectric layer are studied,and the influence of aspect ratio on the characteristics of diffuse discharge plasma is discussed.Subsequently,the effects of wire mesh,the inclination angle of the dielectric plate,and liquid inlet velocity on the flow characteristics of the water film electrode are analyzed.The results show that the non-uniform electric field distribution formed in the sawtooth groove can effectively inhibit the filamentous discharge,and the 1 mm flowing water film is directly used as the electrode,and high-active plasma is formed directly on the lower surface of the water film.In addition,a plasma flowing water treatment device is built to treat the methyl orange solution and observe its decolorization effect.The experimental results show that after 50 min of treatment,the decolorization rate of the methyl orange solution reaches 96%,which provides a new idea for industrial applications of wastewater treatment.

Exploration to generate atmospheric pressure glow discharge plasma in air

Atmospheric pressure glow discharge（APGD） plasma in air has high application value. In this paper, the methods of generating APGD plasma in air are discussed, and the characteristics of dielectric barrier discharge（DBD） in non-uniform electric field are studied. It makes sure that APGD in air is formed by DBD in alternating current electric field with using the absorbing electron capacity of electret materials to provide initial electrons and to end the discharge progress. Through designing electric field to form two-dimensional space varying electric field and three-dimensional space varying electric field, the development of electron avalanches in airgap is suppressed effectively and a large space of APGD plasma in air is generated. Further,through combining electrode structures, a large area of APGD plasma in air is generated. On the other hand, by using the method of increasing the density of initial electrons, millimeter-gap glow discharge in atmospheric pressure air is formed, and a maximum gap distance between electrodes is 8 mm. By using the APGD plasma surface treatment device composed of contact electrodes, the surface modification of high polymer materials such as aramid fiber and polyester are studied and good effect of modifications is obtained. The present paper provides references for the researchers of industrial applications of plasma.

Generation of atmospheric pressure diffuse dielectric barrier discharge based on multiple potentials in air

In order to achieve atmospheric pressure diffuse dielectric barrier discharge(DBD) in air, a helical-helical electrode structure with a floating-voltage electrode is proposed in this paper.Results from an electric field distribution simulation indicate that strong electric fields are formed where the helical-contact electrodes’ insulating layers are in contact with each other, as well as near the floating-voltage electrode, which contributes to the production of a large number of seed electrons. The electric field within the air gap is weak(<3?×?106 V m-1), which inhibits the rapid development of electron avalanches and the formation of filament discharge. The experimental result shows that a 3.0 mm width diffuse DBD is generated in air. Moreover, based on the study of the helical-helical electrode with a floating-voltage electrode, a threedimensional electrode structure is presented, and a three-dimensional diffuse discharge is generated in air by adopting this electrode structure. The plasma studied is stable and demonstrates good diffusion characteristics, and therefore has potential applications in the field of exhaust gas treatment and air purification.

Comparative chloroplast genomes of Ulva prolifera and U.linza(Ulvophyceae)provide genetic resources for the development of interspecific markers

The green seaweeds Ulva linza and U.prolifera are closely related species.They usually co-occur widely and have important ecological significance as primary producers thriving in the intertidal zone.In the Yellow Sea,a genetically unique floating ecotype of U.prolifera even bloomed to cause serious green tides.However,there is still a lack of appropriate molecular markers to distinguish these two species,partially due to limited evaluations on the intraspecific variations in U.prolifera among dif ferent ecotypes.Since organelle genomes could provide rich genetic resources for phylogenetic analysis and development of genetic markers,in this study,the chloroplast genome from one attached population of U.prolifera was completely sequenced,and comparative genomic analyses were performed with other existing chloroplast genomes from U.linza and the floating ecotype of U.prolifera.The results showed that in spite of the high level of collinearity among three genomes,there were plenty of genetic variations especially within the non-coding regions,including introns and gene spacer regions.A strategy was proposed that only those signals of variation,which were identical between two ecotypes of U.prolifera but divergent between U.linza and U.prolifera,were selected to develop the interspecific markers for U.linza and U.prolifera.Two candidate markers,psa B and pet B,were shown to be able to distinguish these two closely related species and were applicable to more attached populations of U.prolifera from a wide range of geographical sources.In addition to the interspecific marker,this study would also provide resources for the development of intraspecific markers for U.prolifera.These markers might contribute to the surveys for Ulva species composition and green tide monitoring especially in the Yellow Sea region.

Study of the influence of discharge loop parameters on anode side on generation characteristics of metal plasma jet in a pulsed vacuum discharge

In a pulsed vacuum discharge,the ejection performance of a metal plasma jet can be effectively improved by preventing charged particles from moving to the anode.In this paper,the effects of resistance and capacitance on the anode side on the discharge characteristics and the generation characteristics of plasma jet are investigated.Results show that the existence of a resistor on the anode side can increase the anode potential,thereby preventing charged particles from entering the anode and promoting the ejection of charged particles along the axis of the insulating sleeve nozzle.The application of a capacitor on the anode side can not only absorb electrons at the initial stage of discharge,increasing the peak value of the cathode hump potential,but also prevent charged particles from moving to the anode,thereby improving the ejection performance of the plasma jet.In addition,the use of a larger resistance and a smaller capacitance can improve the blocking effect on charged particles and further improve the ejection performance of the plasma jet.Results of this study will provide a reference for the improvement of the ejection performance of plasma jets and their applications.

Aviation armament system-of-systems modeling and identification method of vulnerable nodes based on interdependent network

Aiming at the problem that it is difficult to build model and identify the vulnerable equipment for aviation armament System-of-Systems(SoS)due to complex equipment interaction relationships and high confrontation,the interdependent network theory is introduced to solve it.Firstly,a two-layer heterogeneous interdependent network model for aviation armament SoS is proposed,which reflects the information interaction,functional dependency and inter-network dependence effectively.Secondly,using the attack cost to describe the confrontation process and taking the comprehensive impact on kill chains as the entry point,the node importance index and the attack cost measurement method are constructed.Thirdly,the identification of vulnerable nodes is transformed into the optimization problem of node combinatorial selection,and the vulnerable node identification method based on tabu search is proposed.Based on vulnerable nodes,a robustness enhancement strategy for aviation armament SoS network is presented.Finally,the above methods are used to an aerial confrontation SoS,and the results verify the rationality and effectiveness of the proposed methods.

A Pid3 allele from rice cultivar Gumei2 confers resistance to Magnaporthe oryzae

Rice blast, caused by Magnaporthe oryzae, is one of the most devastating diseases. Using map-based strategy and in silico approach we isolated a new rice （Oryza sativa L.） blast resistance allele of Pid3, designated Pi25, from a stable blast resistance cultivar Gumei2. Overexpression analysis and complementation test showed that Pi25 conferred blast resistance to M. oryzae isolate js001-20. Sequence analysis showed that Pi25 was an intronless gene of 2772 nucleotides with single nucleotide substitution in comparison to Pid3 at the nucleotide position 459 and predicatively encoded a typical coiled coil-nucleotide binding site-leucine rich repeat （CC-NBS-LRR） protein of 924 amino acid residuals with 100% identity to Pid3 putative protein. The susceptible allele pi25 in Nipponbare contained a nonsense mutation at the nucleotide position 2209 resulting in a truncated protein with 736 amino acid residuals. In addition, 14 nucleotide substitutions resulting in 10 amino acid substitutions were identified between Pi25 and pi25 upstream the premature stop codon in the susceptible allele. Although the mechanism of Pi25/Pid3-mediated resistance needs to be further investigated, the isolation of the allele would facilitate the utilization of Pi25/Pid3 in rice blast resistance breeding program via transgenic approach and marker assisted selection.

Design and experiment of anti-vibrating and anti-wrapping rotary components for subsoiler cum rotary tiller

The commonly used subsoiling cum rotary tiller machine(SRT)in Northern China is a combination of subsoiler and horizontal rotary tiller,however backfilling of the subsoiling slot,excessive vibration and plant residue wrapping on rotary components has been rarely considered.Therefore,the rotary components and assembly were redesigned to address these issues and to an SRT fitted with IT225 short curve rotary blades behind the V-shape subsoiling slots and IIT245 long curve rotary blades between the tines.Long and short blades were fitted on a rotor in a double helix,with optimal spiral angles of 65° and 90°,and phase angle of 147°and 180°,respectively.Compared with the commonly used SRT(CSRT),the additional anti-wrapping cutting blades in the circumferential and axial direction of ASRT could remove hanging residue on the blade holders,wrapping on the rotor and formation of an isolation layer.Moreover,the cutting edge curve of anti-wrapping cutting blades was an exponential curve.Field tests demonstrated that the redesigned SRT with anti-vibrating and anti-wrapping rotary components(ASRT)had was a significant advancement over the CSRT.Moreover,the working depth of rotary tillage was more stable,while other observations confirmed that backfilling of the subsoiling slot was also improved.

Experiment and analysis of potato-soil separation based on impact recording technology

In order to discover the damage mechanism and improve separation performance in the separation process of potato-soil mixture,the experiment was conducted on an in-house test-bed.The impact recording device and high-speed camera technology were employed in order to obtain the instantaneous dynamics of the potato-soil mixture for detail data analysis.Five vibration intensities were defined according to the vibration frequency and amplitude.It was found that the mean number of impacts and maximum impact acceleration increased significantly as the level of vibration intensity rose.As a result,the separation performance increased significantly,however,the bruising rate also increased to a certain extent.The mathematical relationship between the maximum impact acceleration and the factors of interest,including vibration amplitude,the vibration frequency and the operating speed of the separation sieves was established through the response surface experiment.It was demonstrated that the presented model was capable to reflect the degree of the factors on influencing bruising rate and separation performance.According to the significance on the maximum impact acceleration,the factors of interest were given in a descending order with vibration frequency,vibration amplitude,running speed of the separation sieve.A set of the optimum operating parameters were found to achieve a desired separation performance as follows,the vibration amplitude was 34.1 mm,the vibration frequency was 5.24 Hz,the running speed of the separation sieve was 2.05 m/s;where the maximum impact acceleration was 98.62 g,the relative error was 3.23%,the bruising rate was 1.81%and the separation performance was 98.5%.The presented model can potentially provide a technical reference for further investigation of the separation mechanism and development of measures for reducing the loss of separation.

Double-ejection micro-cathode arc thruster applied to micro-satellite

An innovative double-ejection micro-cathode arc thruster(AC_(d-μ)CAT),which consists of a cylindrical inner anode,a cylindrical outer cathode and two insulating sleeves(an inner insulating sleeve and an outer insulating sleeve),was proposed.The differences in electrical characteristics,plasma parameters and propulsion performance between the newly proposed AC_(d-μ)CAT and a traditionalμCAT were examined.Study results showed that compared to the traditionalμCAT structure,by using the AC_(d-μ)CAT,the peak value of produced thrust was increased 9.3 times,while the amplitude of the ion current and the ion-to-arc ratio were increased 5.4 and 5.9 times(from 1.2%to 7.1%),respectively.In addition,data from Langmuir probe experiments indicated that peak values of the directional propagation speed and density of plasma plume were increased 3.1 times and 4.2 times,respectively.Moreover,plasma plume directional ejection performance was also significantly improved.This study result will provide support for the development of a new-generationμCAT.

医源性胆管损伤的修复时机

1905年Mayo首次报道2例胆总管十二指肠吻合修复胆囊切除术导致的医源性胆管损伤(iatrogenic bile duct injury,IBDI)。其后IBDI经历了两次发生高峰,分别是20世纪60年代开腹胆囊切除术和90年代腹腔镜胆囊切除术(LC)广泛开展时。目前,LC致IBDI发生率为0.104%~0.38%,占全部IBDI的80%~85%,成为导致IBDI的首要原因[1]。站在手术者的角度,手术过程中曾发生IBDI的外科医师占72.3%~80%[2]。但由于IBDI统计的难度,实际发生率可能更高。此外胃大部切除术、肝破裂修补术、肝切除术、ERCP及相关操作导致的IBDI也见于文献。

Simulation-oriented model reuse in cyber-physical systems: A method based on constrained directed graph

Modeling and Simulation of Cyber-Physical Systems(MSCPS)is demanding in terms of immediate response to dynamic and complex changes of CPS.Simulation-oriented model reuse can be used to build a whole CPS model by reusing developed models in a new sim-ulation application,which avoid repeated modeling and thus reduce the redevelopment of submodels.Model composition,one of the important methods,enables model reuse by selecting and adopting diversified integration solutions of simulation components to meet the requirements of simulation application systems.In this paper,a real-time model integration approach for global CPS modeling is proposed,which reuses devel-oped submodels by compositing submodel nodes.Specifically,a constrained directed graph of submodels for the whole system which can meet the simulation requirements is constructed by reverse matching.Submodel properties,including co-simulation distance between submodel nodes,reuse benefit and simulation performance of model nodes,are quantified.Based on the properties,the model-integrated solution for the whole CPS simulation is retrieved throughout the model constrained digraph by the Genetic Algo-rithm(GA).In the experiment,the proposed method is applied to a typical model integrated computing scenario containing multiple model-integration solutions,among which the Pareto optimal solutions are retrieved.Results show that the effectiveness of the model integration method proposed in this paper is verified.

Knowledge-driven material design platform based on the whole-process simulation and modeling

In order to realize the agility,collaboration and visualization of alloy material devel-opment process,a product development platform based on simulation and modeling technologies is established in this study.In this platform,the whole-process simulation module builds multi-level simulation models based on metallurgical mechanisms from the production line level,the thermo-mechanical coupling field level and the microstructure evolution level.The design knowledge management module represents the multi-source heterogeneous material design knowledge through ontology model,including customers’requirement knowledge,material component knowledge,process design knowledge and quality inspection knowledge,and utilizes the case-based reasoning approach to reuse the knowledge.The data-driven modeling module applies machine learning algorithms to mine the relationships between product mechanical properties,material components,and process parameters from historical samples,and utilizes multi-objective optimiza-tion algorithms to find the optimal combination of process parameters.Application of the developed platform in actual steel mills shows that the proposed method helps to improve the efficiency of product design process.