针对铝合金冷金属过渡焊接技术(cold metal transfer,CMT)分析了熔滴过渡过程,以Mast语言构建了相关模型,并测定瞬时送丝速度,给出了CMT过渡周期中送丝速度变化曲线,结合弧焊电源的电路结构,构建了基于Saber的CMT焊机主电路和控制电路...针对铝合金冷金属过渡焊接技术(cold metal transfer,CMT)分析了熔滴过渡过程,以Mast语言构建了相关模型,并测定瞬时送丝速度,给出了CMT过渡周期中送丝速度变化曲线,结合弧焊电源的电路结构,构建了基于Saber的CMT焊机主电路和控制电路仿真平台.通过该平台进行改变峰值持续时间的非一元化焊接仿真,并同实测的电流和电压信号进行对比,探讨了焊接电流、电弧电压、过渡频率、熔滴体积和送丝速度等参数误差.结果表明,仿真与实测值误差较小,均在10%以下,证实了搭建CMT仿真平台的准确性,进而为理解CMT物理过程,优化工艺参数奠定了初步的基础.展开更多
The objective of this paper is to evaluate the coal petrology characteristics of slack middlings(13–0.5 mm)of dense media separation and flotation middlings from Qianjiaying fat coal preparation plant.Phase compositi...The objective of this paper is to evaluate the coal petrology characteristics of slack middlings(13–0.5 mm)of dense media separation and flotation middlings from Qianjiaying fat coal preparation plant.Phase composition,macerals distribution,microlithotype and mineral occurrence of the two middlings were studied by XRD analysis and polarized light microscopy observation.Macerals distribution and wettability of the float-and-sink products separated from the middlings after grinding was investigated to determine the liberation degree.Studies show that there are more vitrinite and mineral,but less inertinite in slack middlings than in flotation middlings.Macerals associated with mineral in slack middlings is 69.85%,by volume,which is 17.86%higher than that in flotation middlings.Minerals in slack middlings are dominated by pyrite and clay,which are disseminated with the diameter less than2 lm.The main mineral in flotation middlings is clay with size range of 2–20 lm.Single macerals in the slack middlings are diffcult to liberate due to the fne-grained minerals.After grinding,macerals associated with minerals in the slack middlings decrease to 46.73%,by volume,which is higher than in flotation middlings by 25.89%,by volume.For slack middlings with poor liberation degree,density fractions below1.8 g/cm3is hydrophobic with contact angle above 71.5°.For the well liberated flotation middlings,there is signifcant wettability difference among the float-and-sink products.This research is the theoretical basis to realize re-separation of middlings.展开更多
With the rapid development of immersive multimedia technologies,360-degree video services have quickly gained popularity and how to ensure sufficient spatial presence of end users when viewing 360-degree videos become...With the rapid development of immersive multimedia technologies,360-degree video services have quickly gained popularity and how to ensure sufficient spatial presence of end users when viewing 360-degree videos becomes a new challenge.In this regard,accurately acquiring users’sense of spatial presence is of fundamental importance for video service providers to improve their service quality.Unfortunately,there is no efficient evaluation model so far for measuring the sense of spatial presence for 360-degree videos.In this paper,we first design an assessment framework to clarify the influencing factors of spatial presence.Related parameters of 360-degree videos and headmounted display devices are both considered in this framework.Well-designed subjective experiments are then conducted to investigate the impact of various influencing factors on the sense of presence.Based on the subjective ratings,we propose a spatial presence assessment model that can be easily deployed in 360-degree video applications.To the best of our knowledge,this is the first attempt in literature to establish a quantitative spatial presence assessment model by using technical parameters that are easily extracted.Experimental results demonstrate that the proposed model can reliably predict the sense of spatial presence.展开更多
文摘针对铝合金冷金属过渡焊接技术(cold metal transfer,CMT)分析了熔滴过渡过程,以Mast语言构建了相关模型,并测定瞬时送丝速度,给出了CMT过渡周期中送丝速度变化曲线,结合弧焊电源的电路结构,构建了基于Saber的CMT焊机主电路和控制电路仿真平台.通过该平台进行改变峰值持续时间的非一元化焊接仿真,并同实测的电流和电压信号进行对比,探讨了焊接电流、电弧电压、过渡频率、熔滴体积和送丝速度等参数误差.结果表明,仿真与实测值误差较小,均在10%以下,证实了搭建CMT仿真平台的准确性,进而为理解CMT物理过程,优化工艺参数奠定了初步的基础.
基金the financial supports by the National Basic Research Program of China(No.2012CB214905)the National Natural Science Foundation of China(No.51274198)the Graduate Education Innovation Project of Jiangsu Province of China(No.CXLX12_0966)
文摘The objective of this paper is to evaluate the coal petrology characteristics of slack middlings(13–0.5 mm)of dense media separation and flotation middlings from Qianjiaying fat coal preparation plant.Phase composition,macerals distribution,microlithotype and mineral occurrence of the two middlings were studied by XRD analysis and polarized light microscopy observation.Macerals distribution and wettability of the float-and-sink products separated from the middlings after grinding was investigated to determine the liberation degree.Studies show that there are more vitrinite and mineral,but less inertinite in slack middlings than in flotation middlings.Macerals associated with mineral in slack middlings is 69.85%,by volume,which is 17.86%higher than that in flotation middlings.Minerals in slack middlings are dominated by pyrite and clay,which are disseminated with the diameter less than2 lm.The main mineral in flotation middlings is clay with size range of 2–20 lm.Single macerals in the slack middlings are diffcult to liberate due to the fne-grained minerals.After grinding,macerals associated with minerals in the slack middlings decrease to 46.73%,by volume,which is higher than in flotation middlings by 25.89%,by volume.For slack middlings with poor liberation degree,density fractions below1.8 g/cm3is hydrophobic with contact angle above 71.5°.For the well liberated flotation middlings,there is signifcant wettability difference among the float-and-sink products.This research is the theoretical basis to realize re-separation of middlings.
基金supported in part by ZTE Industry⁃University⁃Institute Coop⁃eration Funds.
文摘With the rapid development of immersive multimedia technologies,360-degree video services have quickly gained popularity and how to ensure sufficient spatial presence of end users when viewing 360-degree videos becomes a new challenge.In this regard,accurately acquiring users’sense of spatial presence is of fundamental importance for video service providers to improve their service quality.Unfortunately,there is no efficient evaluation model so far for measuring the sense of spatial presence for 360-degree videos.In this paper,we first design an assessment framework to clarify the influencing factors of spatial presence.Related parameters of 360-degree videos and headmounted display devices are both considered in this framework.Well-designed subjective experiments are then conducted to investigate the impact of various influencing factors on the sense of presence.Based on the subjective ratings,we propose a spatial presence assessment model that can be easily deployed in 360-degree video applications.To the best of our knowledge,this is the first attempt in literature to establish a quantitative spatial presence assessment model by using technical parameters that are easily extracted.Experimental results demonstrate that the proposed model can reliably predict the sense of spatial presence.
