Using citizen science data to improve regional bird species list:A case study in Shaanxi,China

An accurate and updated regional bird species checklist is the foundation for biodiversity research and conservation.However,with ongoing climate and landscape changes,tracking the distributions of bird species is challenging,and expert-curated species lists are often limited regarding survey area and timeliness.Birdwatching in China is becoming increasingly popular,and observations recorded by citizen birders are quickly increasing as well.Assessing the value of these data for improving regional species lists and studying bird distribution needs a detailed and quantitative comparison of citizen science data and expert-curated data.We collected observation reports from the China Bird Report Center,the largest online open platform for sharing bird sightings in China.We focused on reports from 2016 to 2019 in Shaanxi Province.For expert-curated species lists,we used three sources:the latest bird field guide published by local ornithologists,the province list from Avibase,and a list generated from overlaying distribution range from BirdLife International with the outline of Shaanxi Province.In addition,we also compared the bird sighting coordinates with the species distribution maps from BirdLife International.Surprisingly,species checklists from different sources have considerable discrepancies,even among lists based on expert knowledge.Including birdwatching data,there are 616 bird species in total,but less than half of the species(294)appear in all checklists,and 17.2%of species are unique to one list.One hundred sixty-three species lack birdwatching records,but birdwatching identified 39 species new to the province.One hundred thirty-six bird species have sighting locations outside the distribution ranges from BirdLife International,suggesting that updates might be needed.The data also showed a clear trend of bird species shifting to higher latitudes than their traditional distributions.While being inadequate for generating a regional species checklist on its own,birdwatching data in China can be a valuable source for complementing expert knowledge.In particular,the coordinate information of bird sighting can help track species distribution shifts.On the other hand,comparing expert-curated lists to birdwatching data can generate a species list for targeted birdwatching and monitoring,which will improve the quality of the birdwatching data in the future.

Drilling process of indexable drill bit based on Coupled Eulerian-Lagrangian method:A simulation study

42CrMo steel has the characteristics of high strength,high wear resistance,high impact resistance,and fatigue resistance.Therefore,drilling 42CrMo steel has always been a challenging task.The indexable drill bit has the advantages of high processing efficiency and low processing cost and has been widely used in the field of aerospace hole processing.To better understand the machining mechanism of the indexable drill bit,this paper uses the Coupled EulerianLagrangian method(CEL)to simulate the three-dimensional drilling model for the first time.The simulation results of the drilling force obtained by the CEL method and Lagrangian method are compared with the experimental results.It is verified that the CEL method is easy to converge and can avoid the problem of program interruption caused by mesh distortion,and the CEL simulation value is more consistent with the actual value.Secondly,the simulation results of cutting force and blade cutting edge node temperature under different process parameters are extracted.The variation of time domain cutting force,frequency domain cutting force and tool temperature with process parameters are obtained.This study provides a new method for the prediction of cutting performance and the optimization of process parameters of indexable drills.