针对复杂环境下高铁轨道入侵异物对列车的安全行驶有严重的威胁,而现有检测方法不能满足实际的高铁轨道异物检测工作,提出一种基于改进YOLOv7的高铁异物入侵检测算法。引入CARAFE算子作为上采样算法,减少输入图像的特征信息损失,增大网...针对复杂环境下高铁轨道入侵异物对列车的安全行驶有严重的威胁,而现有检测方法不能满足实际的高铁轨道异物检测工作,提出一种基于改进YOLOv7的高铁异物入侵检测算法。引入CARAFE算子作为上采样算法,减少输入图像的特征信息损失,增大网络感受野;在YOLOv7模型中引入GhostConv卷积,可以有效地减少模型的计算量和参数量;引入全局注意力机制(Global Attention Mechanisms,GAM),增强全局信息交互能力和表达能力,提高检测性能;采用Alpha_GIoU损失函数,提升小目标的检测能力和模型的收敛速度。实验结果表明,改进后的YOLOv7-CGGA模型的平均检测精度(mean Average Precision,mAP)和平均每秒推理速度(Frames Per Second,FPS)值分别达到96.7%和96.1,与原YOLOv7模型相比,分别提升了1.6%和31.1,较好地平衡了模型的检测精度和效率,可以满足实际的检测需求。展开更多
In order to treat hazardous municipal solid waste incinerator＇s （MSWI） fly ash, a new DC arc plasma furnace was developed. Taking an arc of 100 V/1000 A DC as an example, the heat transfer characteristics of the DC...In order to treat hazardous municipal solid waste incinerator＇s （MSWI） fly ash, a new DC arc plasma furnace was developed. Taking an arc of 100 V/1000 A DC as an example, the heat transfer characteristics of the DC arc plasma, ablation of electrodes, heat properties of the fly ash during melting, heat transfer characteristics of the flue gas, and heat loss of the furnace were analyzed based on the energy conservation law, so as to achieve the total heat information and energy balance during plasma processing, and to provide a theoretical basis for an optimized design of the structure and to improve energy efficiency.展开更多
Fly ash from a municipal solid waste incinerator （MSWI） without preprocessing （original fly ash, OFA） was melted by a direct current （DC） plasma arc furnace to investigate how the feed forms governed the results...Fly ash from a municipal solid waste incinerator （MSWI） without preprocessing （original fly ash, OFA） was melted by a direct current （DC） plasma arc furnace to investigate how the feed forms governed the results. Dioxins in flue gas from stack and bag-filter ash （BFA） were detected. The distribution of heavy metals of Pb, Cd, As, and Cr along the flue gas process system was analyzed. Through a comparison of the results for dioxins and heavy metals in this study and previous work, carrying-over of fly ash particles with the flue gas stream can be deduced. Based on the magnetic induction equation and Navier-Stokes equations, a magnetohydrodynamic （MHD） model for the plasma arc was developed to describe the particle-carrying effect. The results indicate that, a. when melted, the feed forms of MSWI fly ash affect the results significantly; b. it is not preferable to melt MSWI fly ash directly, and efforts should be made to limit the mass transfer of OFA from the plasma furnace.展开更多
Plasma sputtering deposition techniques are good candidates for the fabrication of electrodes used for direct methanol fuel cells （DMFCs）. A house-made plasma sputtering system was used to deposit platinum of 0.1 mg...Plasma sputtering deposition techniques are good candidates for the fabrication of electrodes used for direct methanol fuel cells （DMFCs）. A house-made plasma sputtering system was used to deposit platinum of 0.1 mg/cm^2 onto un-catalyzed gas diffusion layers （GDLs） to form a Pt catalyzed cathode at different radio frequency （RF） powers and sputtering-gas pressures. The sputtered cathodes were assembled in custom-made membrane electrode assemblies （MEAs） with a commercial anode and tested for the electrical performance of the single cell. A custommade MEA with a sputtering prepared cathode was compared with that of a reference membrane electrode assembly made of commercial JM （Johnson Mattey） catalysts （Pt loading per electrode of 0.5 mg/cm^2） under passive methanol supply, ambient temperature and air-breathing conditions. The results showed that the cathode prepared at an input power of 110 W and sputtering-gas pressure of 5.3 Pa exhibited the best cell performance and highest Pt utilization efficiency, which was due to the miniaturization of the Pt particles and formation of the porous catalyst layer. Although the single cell performance of the commercial cathode was better than all the sputtering fabricated cathodes, the Pt utilization efficiency of all the sputtered cathodes was higher than that of the commercial cathode.展开更多
Anodes used for direct methanol fuel cells （DMFCs） were fabricated by magnetron sputtering process. A house-made plasma sputtering system was used to deposit Pt and PtRu onto un-catalyzed gas diffusion layers （GDLs...Anodes used for direct methanol fuel cells （DMFCs） were fabricated by magnetron sputtering process. A house-made plasma sputtering system was used to deposit Pt and PtRu onto un-catalyzed gas diffusion layers （GDLs） at different radio frequency （RF） powers and sputtering- gas pressures. The thin film catalyst layers were characterized by X-ray diffraction, energy dis- persive X-ray analysis, and X-ray photoelectron spectroscopy. The sputtered anodes were assem- bled in custom-made membrane electrode assemblies （MEAs） with a commercial cathode and the electrical performance of the single cell were tested under passive methanol supply, ambient tern- perature and air-breathing conditions. The electrochemical performance of the anodes prepared with PtRu alloy was compared with a reference anode sputtered with Pt only. X-ray diffraction and X-ray photoelectron spectroscopy revealed that platinum and ruthenium existed as a form of alloy. The cell polarization measurements showed that all the PtRu alloy catalysts had better electrochemical performance than the Ptl catalyst, and the Pto.n3Ruo.57 catalyst achieved the best performance.展开更多
Oxidized nanocarbons(ONCs)have been regarded as efficient electrocatalysts for H2O2 production.However,wet chemical procedures involving large volumes of strong acid and long synthetic time are usually needed to obtai...Oxidized nanocarbons(ONCs)have been regarded as efficient electrocatalysts for H2O2 production.However,wet chemical procedures involving large volumes of strong acid and long synthetic time are usually needed to obtain these ONCs.Herein,a plasma activation strategy is developed as a rapid and environmentally benign approach to obtain various ONCs,including oxidized multiwalled carbon nanotubes,single-walled carbon nanotube,graphene,and super P carbon black.After a few minutes of plasma activation,oxygen-containing functional groups and defects can be effectively introduced onto the surface of nanocarbons.Enhanced electrocatalytic activity and selectivity are demonstrated by the plasma-ONCs for H2O2 production.Taking oxidized multiwalled carbon nanotubes as an example,high selectivity(up to 95%)and activity(0.75 V at 1 mA cm^(−2))can be achieved in alkaline solution.Moreover,ex situ x-ray photoelectron spectroscopy and in situ Raman measurements reveal that C–O,C=O,edge defect,and sp2 basal planar defect are probably the active sites.展开更多
文摘针对复杂环境下高铁轨道入侵异物对列车的安全行驶有严重的威胁,而现有检测方法不能满足实际的高铁轨道异物检测工作,提出一种基于改进YOLOv7的高铁异物入侵检测算法。引入CARAFE算子作为上采样算法,减少输入图像的特征信息损失,增大网络感受野;在YOLOv7模型中引入GhostConv卷积,可以有效地减少模型的计算量和参数量;引入全局注意力机制(Global Attention Mechanisms,GAM),增强全局信息交互能力和表达能力,提高检测性能;采用Alpha_GIoU损失函数,提升小目标的检测能力和模型的收敛速度。实验结果表明,改进后的YOLOv7-CGGA模型的平均检测精度(mean Average Precision,mAP)和平均每秒推理速度(Frames Per Second,FPS)值分别达到96.7%和96.1,与原YOLOv7模型相比,分别提升了1.6%和31.1,较好地平衡了模型的检测精度和效率,可以满足实际的检测需求。
基金supported by the Knowledge Innovation Project in the Chinese Academy of Sciences (No. O45CF3A211)
文摘In order to treat hazardous municipal solid waste incinerator＇s （MSWI） fly ash, a new DC arc plasma furnace was developed. Taking an arc of 100 V/1000 A DC as an example, the heat transfer characteristics of the DC arc plasma, ablation of electrodes, heat properties of the fly ash during melting, heat transfer characteristics of the flue gas, and heat loss of the furnace were analyzed based on the energy conservation law, so as to achieve the total heat information and energy balance during plasma processing, and to provide a theoretical basis for an optimized design of the structure and to improve energy efficiency.
基金supported by the Knowledge Innovation Project in Chinese Academy of Sciences (045CF3A211)
文摘Fly ash from a municipal solid waste incinerator （MSWI） without preprocessing （original fly ash, OFA） was melted by a direct current （DC） plasma arc furnace to investigate how the feed forms governed the results. Dioxins in flue gas from stack and bag-filter ash （BFA） were detected. The distribution of heavy metals of Pb, Cd, As, and Cr along the flue gas process system was analyzed. Through a comparison of the results for dioxins and heavy metals in this study and previous work, carrying-over of fly ash particles with the flue gas stream can be deduced. Based on the magnetic induction equation and Navier-Stokes equations, a magnetohydrodynamic （MHD） model for the plasma arc was developed to describe the particle-carrying effect. The results indicate that, a. when melted, the feed forms of MSWI fly ash affect the results significantly; b. it is not preferable to melt MSWI fly ash directly, and efforts should be made to limit the mass transfer of OFA from the plasma furnace.
基金supported by National Natural Science Foundation of China (No. 10975162)the Principal Foundation of Institute of Plasma PhysicsChinese Academy of Sciences (No. 095GZ1156Y)
文摘Plasma sputtering deposition techniques are good candidates for the fabrication of electrodes used for direct methanol fuel cells （DMFCs）. A house-made plasma sputtering system was used to deposit platinum of 0.1 mg/cm^2 onto un-catalyzed gas diffusion layers （GDLs） to form a Pt catalyzed cathode at different radio frequency （RF） powers and sputtering-gas pressures. The sputtered cathodes were assembled in custom-made membrane electrode assemblies （MEAs） with a commercial anode and tested for the electrical performance of the single cell. A custommade MEA with a sputtering prepared cathode was compared with that of a reference membrane electrode assembly made of commercial JM （Johnson Mattey） catalysts （Pt loading per electrode of 0.5 mg/cm^2） under passive methanol supply, ambient temperature and air-breathing conditions. The results showed that the cathode prepared at an input power of 110 W and sputtering-gas pressure of 5.3 Pa exhibited the best cell performance and highest Pt utilization efficiency, which was due to the miniaturization of the Pt particles and formation of the porous catalyst layer. Although the single cell performance of the commercial cathode was better than all the sputtering fabricated cathodes, the Pt utilization efficiency of all the sputtered cathodes was higher than that of the commercial cathode.
基金supported by National Natural Science Foundation of China (No.10975162)the Principal Foundation of Institute of Plasma Physics, Chinese Academy of Sciences (No.095GZ1156Y)
文摘Anodes used for direct methanol fuel cells （DMFCs） were fabricated by magnetron sputtering process. A house-made plasma sputtering system was used to deposit Pt and PtRu onto un-catalyzed gas diffusion layers （GDLs） at different radio frequency （RF） powers and sputtering- gas pressures. The thin film catalyst layers were characterized by X-ray diffraction, energy dis- persive X-ray analysis, and X-ray photoelectron spectroscopy. The sputtered anodes were assem- bled in custom-made membrane electrode assemblies （MEAs） with a commercial cathode and the electrical performance of the single cell were tested under passive methanol supply, ambient tern- perature and air-breathing conditions. The electrochemical performance of the anodes prepared with PtRu alloy was compared with a reference anode sputtered with Pt only. X-ray diffraction and X-ray photoelectron spectroscopy revealed that platinum and ruthenium existed as a form of alloy. The cell polarization measurements showed that all the PtRu alloy catalysts had better electrochemical performance than the Ptl catalyst, and the Pto.n3Ruo.57 catalyst achieved the best performance.
基金National Natural Science Foundation of China(No.12075002)the Outstanding Youth Fund of Anhui Province(No.2008085J21)+1 种基金the Anhui Provincial Supporting Program for Excellent Young Talents in Universities(No.gxyqZD2019005)the Innovation and Entrepreneurship Project of Overseas Returnees in Anhui Province(No.2019LCX018).
文摘Oxidized nanocarbons(ONCs)have been regarded as efficient electrocatalysts for H2O2 production.However,wet chemical procedures involving large volumes of strong acid and long synthetic time are usually needed to obtain these ONCs.Herein,a plasma activation strategy is developed as a rapid and environmentally benign approach to obtain various ONCs,including oxidized multiwalled carbon nanotubes,single-walled carbon nanotube,graphene,and super P carbon black.After a few minutes of plasma activation,oxygen-containing functional groups and defects can be effectively introduced onto the surface of nanocarbons.Enhanced electrocatalytic activity and selectivity are demonstrated by the plasma-ONCs for H2O2 production.Taking oxidized multiwalled carbon nanotubes as an example,high selectivity(up to 95%)and activity(0.75 V at 1 mA cm^(−2))can be achieved in alkaline solution.Moreover,ex situ x-ray photoelectron spectroscopy and in situ Raman measurements reveal that C–O,C=O,edge defect,and sp2 basal planar defect are probably the active sites.
