This paper presents an innovative investigation on prototyping a digital twin(DT)as the platform for human-robot interactive welding and welder behavior analysis.This humanrobot interaction(HRI)working style helps to ...This paper presents an innovative investigation on prototyping a digital twin(DT)as the platform for human-robot interactive welding and welder behavior analysis.This humanrobot interaction(HRI)working style helps to enhance human users'operational productivity and comfort;while data-driven welder behavior analysis benefits to further novice welder training.This HRI system includes three modules:1)a human user who demonstrates the welding operations offsite with her/his operations recorded by the motion-tracked handles;2)a robot that executes the demonstrated welding operations to complete the physical welding tasks onsite;3)a DT system that is developed based on virtual reality(VR)as a digital replica of the physical human-robot interactive welding environment.The DT system bridges a human user and robot through a bi-directional information flow:a)transmitting demonstrated welding operations in VR to the robot in the physical environment;b)displaying the physical welding scenes to human users in VR.Compared to existing DT systems reported in the literatures,the developed one provides better capability in engaging human users in interacting with welding scenes,through an augmented VR.To verify the effectiveness,six welders,skilled with certain manual welding training and unskilled without any training,tested the system by completing the same welding job;three skilled welders produce satisfied welded workpieces,while the other three unskilled do not.A data-driven approach as a combination of fast Fourier transform(FFT),principal component analysis(PCA),and support vector machine(SVM)is developed to analyze their behaviors.Given an operation sequence,i.e.,motion speed sequence of the welding torch,frequency features are firstly extracted by FFT and then reduced in dimension through PCA,which are finally routed into SVM for classification.The trained model demonstrates a 94.44%classification accuracy in the testing dataset.The successful pattern recognition in skilled welder operations should benefit to accelerate n展开更多
Objective To investigate whether photochemical smog emitted during the process of electric arc welding might cause oxidative stress and potential oxidative damage in the bodies of welding operators. Methods Seventy...Objective To investigate whether photochemical smog emitted during the process of electric arc welding might cause oxidative stress and potential oxidative damage in the bodies of welding operators. Methods Seventy electric arc welding operators (WOs) and 70 healthy volunteers (HVs) were enrolled in a randomized controlled study design, in which the levels of vitamin C (VC) and vitamin E (VE) in plasma as well as the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX), and the level of lipoperoxide (LPO) in erythrocytes were determined by spectrophotometry. Results Compared with the average values of the above experimental parameters in the HVs group, the average values of VC and VE in plasma as well as those of SOD, CAT and GPX in erythrocytes in the WOs group were significantly decreased (P<0.005-0.0001), while the average value of LPO in erythrocytes in the WOs group was significantly increased (P<0.0001). The findings from the partial correlation analysis on the controlling of age suggested that with a prolonged duration of exposure to photochemical smog the values of VC, VE, SOD, and GPX, except for CAT, in the WOs were decreased gradually (P<0.05-0.005), the value of LPO in the WOs was increased gradually (P<0.001), and that with the ozone dose increased in the air in each worksite VC, VE, SOD, CAT and GPX decreased (P<0.005-0.001), but LPO increased (P<0.001). The findings from the reliability analysis for the VC, VE, SOD, CAT, GPX, and LPO values which were used to reflect oxidative stress and potential oxidative damage in the WOs showed that the reliability coefficients?alpha (6 items) was 0.8021, P<0.0001, and that the standardized item alpha was 0.9577, P<0.0001. Conclusion Findings in the present study suggest that there exists an oxidative stress induced by long-term exposure to photochemical smog in the bodies of WOs, thereby causing potential oxidative and lipoperoxidative damages in their bodies.展开更多
The new connection assembly program contains four cone-shapes of fixed welders and four bolts.It is used for connecting the cover assembly of a Down-The-Hole( DTH) drill rig and its chassis.The design feasibility and ...The new connection assembly program contains four cone-shapes of fixed welders and four bolts.It is used for connecting the cover assembly of a Down-The-Hole( DTH) drill rig and its chassis.The design feasibility and reliability are evaluated according to the mechanical calculation and finite element method.展开更多
Background: The welding trade includes many industrial activities in both the formal and informal sectors. Workers in this professional environment do not have access to individual and collective means of protection a...Background: The welding trade includes many industrial activities in both the formal and informal sectors. Workers in this professional environment do not have access to individual and collective means of protection adapted to the activity, which exposes them to the dust emitted during their activity and therefore contributes to increasing the risk of developing respiratory disorders in this population. Objective: Our study aimed to evaluate the ventilatory function of metal welders in the city of Dakar. Method: This was a comparative study based on the analysis of the spirometric parameters of metal welders working in the city of Dakar (Senegal) with those of a control group of the same kind, selected from the general population. Measurements of forced expiratory volume in the first second (FEV1), forced vital capacity (FVC), peak expiratory flow (PEF) and maximum mid expiratory flow (MMEF) were measured. Results: A total of 75 men between the ages of 19 and 61 were recruited and divided into two groups (43 controls and 32 welders). The welding population had more frequent distal and central obstructions and pulmonary restriction compared to the control group. The metals most commonly used by welders were aluminum for welders who had an obstruction, while for those who had a restriction, iron was the most used metal. Signs of metal fever were frequently found in welders, especially those with ventilatory disorders. Conclusion: The prevalence of respiratory disorders observed is close to that observed in industrial environments, where exposure levels are the highest. The lack of personal protective equipment could also be a significant risk factor in the development of these disorders.展开更多
[背景]上海市松江区是上海市工业产业集中的郊区之一,辖区内接触职业病危害因素劳动者众多,其中因长期接触生产性粉尘导致的尘肺病是松江区最主要的职业病,尤其以电焊工尘肺为主。因此,如何有效控制辖区电焊作业场所电焊烟尘浓度成为劳...[背景]上海市松江区是上海市工业产业集中的郊区之一,辖区内接触职业病危害因素劳动者众多,其中因长期接触生产性粉尘导致的尘肺病是松江区最主要的职业病,尤其以电焊工尘肺为主。因此,如何有效控制辖区电焊作业场所电焊烟尘浓度成为劳动者、企业和职业卫生监管部门关注的重点。[目的]了解上海市松江区哨点企业中劳动者电焊烟尘暴露水平,并分析其影响因素。[方法]2014-2018年,采用三阶段分层抽样方法抽取松江区62家企业共228名焊接作业劳动者为研究对象。采用个体采样仪采样,采用重量法测定工作场所电焊烟尘8 h时间加权平均浓度(TWA)。采用现场调查问卷,收集和分析可能影响暴露的因素。[结果]本研究共获得228份电焊烟尘样品,8 h TWA中位数为1.76 mg/m^3,总超标率为17.54%。5年间电焊烟尘超标率差异有统计学意义(χ^2=17.46,P <0.01),呈现逐渐下降趋势(P趋势<0.01)。专用设备制造业企业电焊烟尘超标率(30.19%)和8 h TWA(2.40 mg/m^3)最高,不同行业间电焊烟尘超标率和8 h TWA差异有统计学意义(χ^2=10.66,P <0.05;H=15.78,P <0.01)。连续作业超标率(23.08%)和8 h TWA(2.10 mg/m^3)高于间歇作业(χ^2=4.05,P <0.05;Z=-3.17,P <0.01)。CO2气体保护焊的超标率(22.09%)高于氩弧焊和焊条电弧焊(χ^2=6.19,P <0.05;P <0.05);CO2气体保护焊的8 h TWA(1.92 mg/m^3)也高于氩弧焊(Z=-3.84,P <0.01)。通风效果较差的作业场所中电焊烟尘超标率(34.29%)和8 h TWA(3.63 mg/m^3)高于通风效果好的作业场所(χ^2=8.70,P <0.05;H=44.73,P <0.01)。[结论]2014-2018年上海市松江区哨点企业电焊烟尘暴露水平和超标率呈现下降趋势。作业场所通风效果、焊接工艺类型和作业特征是影响电焊烟尘暴露水平的主要因素。今后仍要对通风效果差、连续作业和CO2气体保护焊等重点岗位的电焊烟尘暴露进行防控。展开更多
文摘This paper presents an innovative investigation on prototyping a digital twin(DT)as the platform for human-robot interactive welding and welder behavior analysis.This humanrobot interaction(HRI)working style helps to enhance human users'operational productivity and comfort;while data-driven welder behavior analysis benefits to further novice welder training.This HRI system includes three modules:1)a human user who demonstrates the welding operations offsite with her/his operations recorded by the motion-tracked handles;2)a robot that executes the demonstrated welding operations to complete the physical welding tasks onsite;3)a DT system that is developed based on virtual reality(VR)as a digital replica of the physical human-robot interactive welding environment.The DT system bridges a human user and robot through a bi-directional information flow:a)transmitting demonstrated welding operations in VR to the robot in the physical environment;b)displaying the physical welding scenes to human users in VR.Compared to existing DT systems reported in the literatures,the developed one provides better capability in engaging human users in interacting with welding scenes,through an augmented VR.To verify the effectiveness,six welders,skilled with certain manual welding training and unskilled without any training,tested the system by completing the same welding job;three skilled welders produce satisfied welded workpieces,while the other three unskilled do not.A data-driven approach as a combination of fast Fourier transform(FFT),principal component analysis(PCA),and support vector machine(SVM)is developed to analyze their behaviors.Given an operation sequence,i.e.,motion speed sequence of the welding torch,frequency features are firstly extracted by FFT and then reduced in dimension through PCA,which are finally routed into SVM for classification.The trained model demonstrates a 94.44%classification accuracy in the testing dataset.The successful pattern recognition in skilled welder operations should benefit to accelerate n
文摘Objective To investigate whether photochemical smog emitted during the process of electric arc welding might cause oxidative stress and potential oxidative damage in the bodies of welding operators. Methods Seventy electric arc welding operators (WOs) and 70 healthy volunteers (HVs) were enrolled in a randomized controlled study design, in which the levels of vitamin C (VC) and vitamin E (VE) in plasma as well as the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX), and the level of lipoperoxide (LPO) in erythrocytes were determined by spectrophotometry. Results Compared with the average values of the above experimental parameters in the HVs group, the average values of VC and VE in plasma as well as those of SOD, CAT and GPX in erythrocytes in the WOs group were significantly decreased (P<0.005-0.0001), while the average value of LPO in erythrocytes in the WOs group was significantly increased (P<0.0001). The findings from the partial correlation analysis on the controlling of age suggested that with a prolonged duration of exposure to photochemical smog the values of VC, VE, SOD, and GPX, except for CAT, in the WOs were decreased gradually (P<0.05-0.005), the value of LPO in the WOs was increased gradually (P<0.001), and that with the ozone dose increased in the air in each worksite VC, VE, SOD, CAT and GPX decreased (P<0.005-0.001), but LPO increased (P<0.001). The findings from the reliability analysis for the VC, VE, SOD, CAT, GPX, and LPO values which were used to reflect oxidative stress and potential oxidative damage in the WOs showed that the reliability coefficients?alpha (6 items) was 0.8021, P<0.0001, and that the standardized item alpha was 0.9577, P<0.0001. Conclusion Findings in the present study suggest that there exists an oxidative stress induced by long-term exposure to photochemical smog in the bodies of WOs, thereby causing potential oxidative and lipoperoxidative damages in their bodies.
文摘The new connection assembly program contains four cone-shapes of fixed welders and four bolts.It is used for connecting the cover assembly of a Down-The-Hole( DTH) drill rig and its chassis.The design feasibility and reliability are evaluated according to the mechanical calculation and finite element method.
文摘Background: The welding trade includes many industrial activities in both the formal and informal sectors. Workers in this professional environment do not have access to individual and collective means of protection adapted to the activity, which exposes them to the dust emitted during their activity and therefore contributes to increasing the risk of developing respiratory disorders in this population. Objective: Our study aimed to evaluate the ventilatory function of metal welders in the city of Dakar. Method: This was a comparative study based on the analysis of the spirometric parameters of metal welders working in the city of Dakar (Senegal) with those of a control group of the same kind, selected from the general population. Measurements of forced expiratory volume in the first second (FEV1), forced vital capacity (FVC), peak expiratory flow (PEF) and maximum mid expiratory flow (MMEF) were measured. Results: A total of 75 men between the ages of 19 and 61 were recruited and divided into two groups (43 controls and 32 welders). The welding population had more frequent distal and central obstructions and pulmonary restriction compared to the control group. The metals most commonly used by welders were aluminum for welders who had an obstruction, while for those who had a restriction, iron was the most used metal. Signs of metal fever were frequently found in welders, especially those with ventilatory disorders. Conclusion: The prevalence of respiratory disorders observed is close to that observed in industrial environments, where exposure levels are the highest. The lack of personal protective equipment could also be a significant risk factor in the development of these disorders.
文摘[背景]上海市松江区是上海市工业产业集中的郊区之一,辖区内接触职业病危害因素劳动者众多,其中因长期接触生产性粉尘导致的尘肺病是松江区最主要的职业病,尤其以电焊工尘肺为主。因此,如何有效控制辖区电焊作业场所电焊烟尘浓度成为劳动者、企业和职业卫生监管部门关注的重点。[目的]了解上海市松江区哨点企业中劳动者电焊烟尘暴露水平,并分析其影响因素。[方法]2014-2018年,采用三阶段分层抽样方法抽取松江区62家企业共228名焊接作业劳动者为研究对象。采用个体采样仪采样,采用重量法测定工作场所电焊烟尘8 h时间加权平均浓度(TWA)。采用现场调查问卷,收集和分析可能影响暴露的因素。[结果]本研究共获得228份电焊烟尘样品,8 h TWA中位数为1.76 mg/m^3,总超标率为17.54%。5年间电焊烟尘超标率差异有统计学意义(χ^2=17.46,P <0.01),呈现逐渐下降趋势(P趋势<0.01)。专用设备制造业企业电焊烟尘超标率(30.19%)和8 h TWA(2.40 mg/m^3)最高,不同行业间电焊烟尘超标率和8 h TWA差异有统计学意义(χ^2=10.66,P <0.05;H=15.78,P <0.01)。连续作业超标率(23.08%)和8 h TWA(2.10 mg/m^3)高于间歇作业(χ^2=4.05,P <0.05;Z=-3.17,P <0.01)。CO2气体保护焊的超标率(22.09%)高于氩弧焊和焊条电弧焊(χ^2=6.19,P <0.05;P <0.05);CO2气体保护焊的8 h TWA(1.92 mg/m^3)也高于氩弧焊(Z=-3.84,P <0.01)。通风效果较差的作业场所中电焊烟尘超标率(34.29%)和8 h TWA(3.63 mg/m^3)高于通风效果好的作业场所(χ^2=8.70,P <0.05;H=44.73,P <0.01)。[结论]2014-2018年上海市松江区哨点企业电焊烟尘暴露水平和超标率呈现下降趋势。作业场所通风效果、焊接工艺类型和作业特征是影响电焊烟尘暴露水平的主要因素。今后仍要对通风效果差、连续作业和CO2气体保护焊等重点岗位的电焊烟尘暴露进行防控。
