Simulation Analysis of Stress Field of Walnut Shell Composite Powder in Laser Additive Manufacturing Forming

A calculation model of stress field in laser additive manufacturing of walnut shell composite powder(walnut shell/Co-PES powder)was established.The DFLUX subroutine was used to implement the moveable application of a double ellipsoid heat source by considering the mechanical properties varying with temperature.The stress field was simulated by the sequential coupling method,and the experimental results were in good accordance with the simulation results.In addition,the distribution and variation of stress and strain field were obtained in the process of laser additive manufacturing of walnut shell composite powder.The displacement of laser additive manufacturing walnut shell composite parts gradually decreased with increasing preheating temperature,decreasing laser power and increasing scanning speed.During the cooling process,the displacement of laser additive manufacturing of walnut shell composite parts gradually increased with the increasing preheating temperature,decreasing scanning speed and increasing laser power.

Association rule mining algorithm based on Spark for pesticide transaction data analyses

With the development of smart agriculture,the accumulation of data in the field of pesticide regulation has a certain scale.The pesticide transaction data collected by the Pesticide National Data Center alone produces more than 10 million records daily.However,due to the backward technical means,the existing pesticide supervision data lack deep mining and usage.The Apriori algorithm is one of the classic algorithms in association rule mining,but it needs to traverse the transaction database multiple times,which will cause an extra IO burden.Spark is an emerging big data parallel computing framework with advantages such as memory computing and flexible distributed data sets.Compared with the Hadoop MapReduce computing framework,IO performance was greatly improved.Therefore,this paper proposed an improved Apriori algorithm based on Spark framework,ICAMA.The MapReduce process was used to support the candidate set and then to generate the candidate set.After experimental comparison,when the data volume exceeds 250 Mb,the performance of Spark-based Apriori algorithm was 20%higher than that of the traditional Hadoop-based Apriori algorithm,and with the increase of data volume,the performance improvement was more obvious.