Abstract Heavy metals in water can be deposited on graphite flakes, which can be used as an enrichment method for laser-induced breakdown spectroscopy （LIBS） and is studied in this paper. The graphite samples were p...Abstract Heavy metals in water can be deposited on graphite flakes, which can be used as an enrichment method for laser-induced breakdown spectroscopy （LIBS） and is studied in this paper. The graphite samples were prepared with an automatic device, which was composed of a loading and unloading module, a quantitatively adding solution module, a rapid heating and drying module and a precise rotating module. The experimental results showed that the sample preparation methods had no significant effect on sample distribution and the LIBS signal accumulated in 20 pulses was stable and repeatable. With an increasing amount of the sample solution on the graphite flake, the peak intensity at Cu I 324.75 nm accorded with the exponential function with a correlation coefficient of 0.9963 and the background intensity remained unchanged. The limit of detection （LOD） was calculated through linear fitting of the peak intensity versus the concentration. The LOD decreased rapidly with an increasing amount of sample solution until the amount exceeded 20 mL and the correlation coefficient of exponential function fitting was 0.991. The LOD of Pb, Ni, Cd, Cr and Zn after evaporating different amounts of sample solution on the graphite flakes was measured and the variation tendency of their LOD with sample solution amounts was similar to the tendency for Cu. The experimental data and conclusions could provide a reference for automatic sample preparation and heavy metal in situ detection.展开更多
To increase the machine accuracy by improving the stiffness of bearings,a preload was applied to bearings.A variable preload technology was necessary to perform machining processes in both low and high speed regions.A...To increase the machine accuracy by improving the stiffness of bearings,a preload was applied to bearings.A variable preload technology was necessary to perform machining processes in both low and high speed regions.An automatic variable preload device was fabricated using an eccentric mass.By installing the fabricated device on a spindle,the effect of the automatic variable preload device on the performance of the spindle was analyzed.In the results of the vibration measurement of the spindle,the vibration is increased by 20%-37% according to measurement points at the maximum rotation speed of 5 000 r/min.And,in the results of the noise measurement of the spindle,the spindle rotation speed is increased by about 1.9% and 1.5% at the front and side of the spindle,respectively.Based on the results of this analysis,an improved method that reduces such effects on the performance of the spindle is proposed.展开更多
The principle of an automatic piecing device is presented, and the mathematic model of a specific combined mechanism of the automatic piecing device is analysed. The kinematics and dynamics equation of the combined me...The principle of an automatic piecing device is presented, and the mathematic model of a specific combined mechanism of the automatic piecing device is analysed. The kinematics and dynamics equation of the combined mechanism is established on the basis of the mathematic model. By the virtual prototype technology, the motion of this mechanism is simulated, whose result is post-processed by ADAMS. To improve the output motion, according to the simulation output and automatic piecing device's practical working condition, the optimisation of the cam mechanism is carried out by finite difference method. The simulation result of this combined mechanism turns out in accordance with its theoretical analysis of virtual prototype in this research, which, therefore, lays a principle basis for the further study of automatic piecing device.展开更多
Aiming at the problems of low success rate and high seedling injury rate of automatic vegetable transplanting,this study focused on cabbage substrate block seedlings and developed a progressive push-out automatic seed...Aiming at the problems of low success rate and high seedling injury rate of automatic vegetable transplanting,this study focused on cabbage substrate block seedlings and developed a progressive push-out automatic seedling device controlled by a PLC system.Based on the friction mechanical properties of seedlings-tray during seedling taking,the collision rebound theoretical analysis of substrate block seedling delivery and the finite element simulation analysis of the seedling taking mechanism were carried out to determine the conditions for stable seedling taking and delivery of the device and the working parameters of the key mechanisms.To evaluate individual parameter effects,a test bench was built,and the effective ranges of key factors were subsequently determined.Three key experimental factors,the inclination angle of the limit guide plate,the seedling separation channel width,and the seedling separation cylinder pressure,were investigated using an L9(34)orthogonal array design with blockage rate and breakage rate as evaluation metrics.The range and variance analysis methods were employed to determine the relative significance of each factor’s influence on the performance indicators.The optimal parameters were determined as:the inclination angle of the limiting guide plate was 3.5°,the width of the seedling separation channel was 50 mm,and the pressure of the seedling separation cylinder was 0.6 MPa.Under these conditions,the seedling taking effect was significantly improved:the blockage rate was 2.46%,the breakage rate was 3.18%,and the seedling taking success rate was 94.36%.The optimal parameter combination was verified by the experiment:the average blockage rate was 3.23%,the average breakage rate was 3.68%,and the average success rate was 93.09%.Compared with the orthogonal experiment,the relative success rate error was 1.27%,indicating that the device has high stability.This study will provide a reference for the design of automatic vegetable transplanters.展开更多
Comments were made on some thought-provoking articles,which included articles that dealt with cardiac arrest(CA).Two articles on CA elaborate on the role of automated compression devices to provide chest compressions ...Comments were made on some thought-provoking articles,which included articles that dealt with cardiac arrest(CA).Two articles on CA elaborate on the role of automated compression devices to provide chest compressions during cardiopulmonary resuscitation(CPR)in“hostile”environments and on a predictive model in cases of out-of-hospital CA(OHCA).CPR after CA has been practiced for centuries,and the evolution until current modern-day practices are discussed.The delay in adopting efficient techniques of resuscitation by the medical community for decades is also touched upon.Both in-hospital and OHCA are discussed along with guidelines and strategies to improve outcomes.Areas of possible research in the future are mentioned.展开更多
Background:Our aim was to evaluate the sensitivity and specificity of the automated computer-based Alberta Stroke Program Early CT Score(e-ASPECTS)for acute stroke patients and compare the result with physicians at di...Background:Our aim was to evaluate the sensitivity and specificity of the automated computer-based Alberta Stroke Program Early CT Score(e-ASPECTS)for acute stroke patients and compare the result with physicians at different levels.Methods:In our center,e-ASPECTS and 9 physicians at different levels retrospectively and blindly assessed baseline computed tomography(CT)images of 55 patients.Sensitivity,specificity,receiver-operating characteristic curves,Bland–Altman plots with mean score error,and Matthews correlation coefficients were calculated.Comparisons were made between the scores by physicians and e-ASPECTS with diffusion-weighted imaging(DWI)being the ground truth.Two methods for clustered data were used to estimate sensitivity and specificity in the region-based analysis.Results:In total,1100(55 patients×20 regions per patient)ASPECTS regions were scored.In the region-based analysis,sensitivity of e-ASPECTS was better than junior doctors and residents(0.576 vs 0.165 and 0.111,p<0.05)but inferior to senior doctors(0.576 vs 0.617).Specificity was lower than junior doctors and residents(0.883 vs 0.971 and 0.914)but higher than senior doctors(0.883 vs 0.809,p<0.05).E-ASPECTS had the best Matthews correlation coefficient of 0.529,compared to senior doctors,junior doctors,and residents(0.463,0.251,and 0.087,respectively).Conclusions:e-ASPECTS showed a similar performance to that of senior physicians in the assessment of brain CT of acute ischemic stroke patients with the Alberta Stroke Program Early CT score method.展开更多
基金supported by National Natural Science Foundation of China(No.60908018)National High Technology Research and Development Program of China(No.2013AA065502)Anhui Province Outstanding Youth Science Fund of China(No.1108085J19)
文摘Abstract Heavy metals in water can be deposited on graphite flakes, which can be used as an enrichment method for laser-induced breakdown spectroscopy （LIBS） and is studied in this paper. The graphite samples were prepared with an automatic device, which was composed of a loading and unloading module, a quantitatively adding solution module, a rapid heating and drying module and a precise rotating module. The experimental results showed that the sample preparation methods had no significant effect on sample distribution and the LIBS signal accumulated in 20 pulses was stable and repeatable. With an increasing amount of the sample solution on the graphite flake, the peak intensity at Cu I 324.75 nm accorded with the exponential function with a correlation coefficient of 0.9963 and the background intensity remained unchanged. The limit of detection （LOD） was calculated through linear fitting of the peak intensity versus the concentration. The LOD decreased rapidly with an increasing amount of sample solution until the amount exceeded 20 mL and the correlation coefficient of exponential function fitting was 0.991. The LOD of Pb, Ni, Cd, Cr and Zn after evaporating different amounts of sample solution on the graphite flakes was measured and the variation tendency of their LOD with sample solution amounts was similar to the tendency for Cu. The experimental data and conclusions could provide a reference for automatic sample preparation and heavy metal in situ detection.
基金Project(2011-0027035) supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF)funded by the Ministry of Education,Science and Technology,Korea
文摘To increase the machine accuracy by improving the stiffness of bearings,a preload was applied to bearings.A variable preload technology was necessary to perform machining processes in both low and high speed regions.An automatic variable preload device was fabricated using an eccentric mass.By installing the fabricated device on a spindle,the effect of the automatic variable preload device on the performance of the spindle was analyzed.In the results of the vibration measurement of the spindle,the vibration is increased by 20%-37% according to measurement points at the maximum rotation speed of 5 000 r/min.And,in the results of the noise measurement of the spindle,the spindle rotation speed is increased by about 1.9% and 1.5% at the front and side of the spindle,respectively.Based on the results of this analysis,an improved method that reduces such effects on the performance of the spindle is proposed.
文摘The principle of an automatic piecing device is presented, and the mathematic model of a specific combined mechanism of the automatic piecing device is analysed. The kinematics and dynamics equation of the combined mechanism is established on the basis of the mathematic model. By the virtual prototype technology, the motion of this mechanism is simulated, whose result is post-processed by ADAMS. To improve the output motion, according to the simulation output and automatic piecing device's practical working condition, the optimisation of the cam mechanism is carried out by finite difference method. The simulation result of this combined mechanism turns out in accordance with its theoretical analysis of virtual prototype in this research, which, therefore, lays a principle basis for the further study of automatic piecing device.
基金supported by the Fundamental Research Fund of the Chinese Academy of Agricultural Sciences at the Institute Level(Grant No.S202409)Jiangsu Modern Agricultural Machinery Equipment and Technology Demonstration and Promotion Project(Grant No.NJ2023-11)+2 种基金National Key R&D Program of China(Grant No.2023YFD2300700)Key Laboratory of Agricultural Equipment for Hilly and Mountainous Areas in Southeastern China(Co-construction by Ministry and Province)Ministry of Agriculture and Rural Affairs(Grant No.QSKF2023006).
文摘Aiming at the problems of low success rate and high seedling injury rate of automatic vegetable transplanting,this study focused on cabbage substrate block seedlings and developed a progressive push-out automatic seedling device controlled by a PLC system.Based on the friction mechanical properties of seedlings-tray during seedling taking,the collision rebound theoretical analysis of substrate block seedling delivery and the finite element simulation analysis of the seedling taking mechanism were carried out to determine the conditions for stable seedling taking and delivery of the device and the working parameters of the key mechanisms.To evaluate individual parameter effects,a test bench was built,and the effective ranges of key factors were subsequently determined.Three key experimental factors,the inclination angle of the limit guide plate,the seedling separation channel width,and the seedling separation cylinder pressure,were investigated using an L9(34)orthogonal array design with blockage rate and breakage rate as evaluation metrics.The range and variance analysis methods were employed to determine the relative significance of each factor’s influence on the performance indicators.The optimal parameters were determined as:the inclination angle of the limiting guide plate was 3.5°,the width of the seedling separation channel was 50 mm,and the pressure of the seedling separation cylinder was 0.6 MPa.Under these conditions,the seedling taking effect was significantly improved:the blockage rate was 2.46%,the breakage rate was 3.18%,and the seedling taking success rate was 94.36%.The optimal parameter combination was verified by the experiment:the average blockage rate was 3.23%,the average breakage rate was 3.68%,and the average success rate was 93.09%.Compared with the orthogonal experiment,the relative success rate error was 1.27%,indicating that the device has high stability.This study will provide a reference for the design of automatic vegetable transplanters.
文摘Comments were made on some thought-provoking articles,which included articles that dealt with cardiac arrest(CA).Two articles on CA elaborate on the role of automated compression devices to provide chest compressions during cardiopulmonary resuscitation(CPR)in“hostile”environments and on a predictive model in cases of out-of-hospital CA(OHCA).CPR after CA has been practiced for centuries,and the evolution until current modern-day practices are discussed.The delay in adopting efficient techniques of resuscitation by the medical community for decades is also touched upon.Both in-hospital and OHCA are discussed along with guidelines and strategies to improve outcomes.Areas of possible research in the future are mentioned.
基金supported by the National Key Research and Development Program of China(2016YFC1301500)Beijing Hospitals Authority Youth Programme(QML20170502)China Postdoctoral Science Foundation(2020-YJ-008).
文摘Background:Our aim was to evaluate the sensitivity and specificity of the automated computer-based Alberta Stroke Program Early CT Score(e-ASPECTS)for acute stroke patients and compare the result with physicians at different levels.Methods:In our center,e-ASPECTS and 9 physicians at different levels retrospectively and blindly assessed baseline computed tomography(CT)images of 55 patients.Sensitivity,specificity,receiver-operating characteristic curves,Bland–Altman plots with mean score error,and Matthews correlation coefficients were calculated.Comparisons were made between the scores by physicians and e-ASPECTS with diffusion-weighted imaging(DWI)being the ground truth.Two methods for clustered data were used to estimate sensitivity and specificity in the region-based analysis.Results:In total,1100(55 patients×20 regions per patient)ASPECTS regions were scored.In the region-based analysis,sensitivity of e-ASPECTS was better than junior doctors and residents(0.576 vs 0.165 and 0.111,p<0.05)but inferior to senior doctors(0.576 vs 0.617).Specificity was lower than junior doctors and residents(0.883 vs 0.971 and 0.914)but higher than senior doctors(0.883 vs 0.809,p<0.05).E-ASPECTS had the best Matthews correlation coefficient of 0.529,compared to senior doctors,junior doctors,and residents(0.463,0.251,and 0.087,respectively).Conclusions:e-ASPECTS showed a similar performance to that of senior physicians in the assessment of brain CT of acute ischemic stroke patients with the Alberta Stroke Program Early CT score method.
