As one of the most popular visual programming languages,Scratch has a lot of evaluation around it.Reasonable evaluation can help programmers understand their projects better.At the same time,it can also provide a reference for them to browse other projects in the online community.Most of the existing evaluations on Scratch are carried from three perspectives:Computational Thinking(CT)ability,visual presentation aesthetics,and code quality.Among them,the assessment of CT and code quality is mainly carried out from the program script,while the evaluation of visual aesthetics is analyzed from the perspective of image sequences generated by project execution.The single-view evaluation focuses on the performance of a program in a certain aspect and is one-sided.In this paper,we propose a multi-view evaluation framework to integrate various evaluations using different policies.We quantitatively analyze the assessment of different views driven by data.Combined with overall evaluations that represent human opinions,we analyze their differences and connections.Through experiments,we determine the weights of different integration policies,the proposed multi-view evaluation method can generate evaluation results similar to human opinions.
Vibration-assisted grinding is one of the most promising technologies for manufacturing optical components due to its efficiency and quality advantages.However,the damage and crack propagation mechanisms of materials in vibration-assisted grinding are not well understood.In order to elucidate the mechanism of abrasive scratching during vibration-assisted grinding,a kinematic model of vibration scratching was developed.The influence of process parameters on the evolution of vibration scratches to indentation or straight scratches is revealed by displacement metrics and velocity metrics.Indentation,scratch and vibration scratch experiments were performed on quartz glass,and the results showed that the vibration scratch cracks are a combination of indentation cracks and scratch cracks.Vibration scratch cracks change from indentation cracks to scratch cracks as the indenter moves from the entrance to the exit of the workpiece or as the vibration frequency changes from high to low.A vertical vibration scratch stress field model is established for the first time,which reveals that the maximum principal stress and tensile stress distribution is the fundamental cause for inducing the transformation of the vibration scratch cracking system.This model provides a theoretical basis for understanding of the mechanism of material damage and crack propagation during vibration-assisted grinding.
