The dynamic behaviors of the keyhole and weld pool are coupled together in plasma arc welding, and the geometric variations of both the keyhole and the weld pool determine the weld quality. It is of great significance...The dynamic behaviors of the keyhole and weld pool are coupled together in plasma arc welding, and the geometric variations of both the keyhole and the weld pool determine the weld quality. It is of great significance to simultaneously sense and monitor the keyhole and the weld pool behaviors by using a single low-cost vision sensor in plasma arc welding process. In this study, the keyhole and weld pool were observed and measured under different levels of welding current by using the near infrared sensing technology and the charge coupled device （CCD） sensing system. The shapes and relative position of weld pool and keyhole under different conditions were compared and analyzed. The observation results lay solid foundation for controlling weld quality and understanding the underlying process mechanisms.展开更多
In this paper,for the first time,an experimental proof of concept for utilising time reversal(TR)in the acoustic regime to localise partial discharge(PD)sources was presented using a single sensor.To achieve this,an e...In this paper,for the first time,an experimental proof of concept for utilising time reversal(TR)in the acoustic regime to localise partial discharge(PD)sources was presented using a single sensor.To achieve this,an experimental setup comprising a water tank,acoustic transducers for signal transmission and reception,and 2D scanners was developed.The performance of the proposed method was evaluated across various scenarios,encompassing different PD source locations and sensor placements,barriers obstructing the line of sight between the receiving sensor and PD sources,varying levels of noise,and different frequency bandwidths for the PD sources.The experimental results demonstrate a near-zero localisation error in all considered examples.The achieved resolution was approximately half of the minimum wavelength.Furthermore,the acoustic TR method exhibits remarkable precision in source localisation,even when faced with obstacles such as a multi-layered metallic cylinder and in scenarios lacking a direct line of sight between the sensor and the source.The accuracy of acoustic TR's localisation remained robust in the presence of noise,showcasing resilience at signal-to-noise ratio levels as low as−20 dB.Additionally,the performance of the acoustic TR method remained consistent across a broad frequency spectrum,spanning from 60 to 200 kHz.展开更多
A method for the multi target locating and tracking with the multi sensor in a field artillery system is studied. A general modeling structure of the system is established. Based on concepts of cluster and closed ba...A method for the multi target locating and tracking with the multi sensor in a field artillery system is studied. A general modeling structure of the system is established. Based on concepts of cluster and closed ball, an algorithm is put forward for multi sensor multi target data fusion and an optimal solution for state estimation is presented. The simulation results prove the algorithm works well for the multi stationary target locating and the multi moving target tracking under the condition of the sparse target environment. Therefore, this method can be directly applied to the field artillery C 3I system.展开更多
Optical nanoparticles are nowadays one of the key elements of photonics.They do not only allow optical imaging of a plethora of systems(from cells to microelectronics),but,in many cases,they also behave as highly sens...Optical nanoparticles are nowadays one of the key elements of photonics.They do not only allow optical imaging of a plethora of systems(from cells to microelectronics),but,in many cases,they also behave as highly sensitive remote sensors.In recent years,it has been demonstrated the success of optical tweezers in isolating and manipulating individual optical nanoparticles.This has opened the door to high resolution single particle scanning and sensing.In this quickly growing field,it is now necessary to sum up what has been achieved so far to identify the appropriate system and experimental set-up required for each application.In this review article we summarize the most relevant results in the field of optical trapping of individual optical nanoparticles.After systematic bibliographic research,we identify the main families of optical nanoparticles in which optical trapping has been demonstrated.For each case,the main advances and applications have been described.Finally,we also include our critical opinion about the future of the field,identifying the challenges that we are facing.展开更多
Single crystal fibers(SCF)are considered to be a combination of bulk crystals and conventional fibers,thereby possessing the stable physical and chemical properties accompanied with excellent waveguide properties.This...Single crystal fibers(SCF)are considered to be a combination of bulk crystals and conventional fibers,thereby possessing the stable physical and chemical properties accompanied with excellent waveguide properties.This paper gives a detailed introduction to the development history of single crystal fibers,including the evolution of the growth technique and the optimization of the growth process.Laser-heated pedestal growth(LHPG)and Micro-pulling-down(μ-PD)methods are considered to be the most widely used growth techniques for growing single crystal fibers,and the advantages of the two methods are also introduced in detail.The second part of this paper describes the characterization of single crystal fibers,including diameter fluctuation,crystal quality and optical losses.A series of cladding approaches for SCF,such as magnetron sputtering,sol-gel,liquid phase epitaxy,co-drawing LHPG,ion implantation and micro-structure cladding will be reviewed.In addition,the research status of single crystal fiber laser and single crystal fiber sensor are also summarized in view of the current research foundation.展开更多
The nanopore size effect on translocation of poly(dT)30through Si3N4 membrane is investigated.In this paper,we report that the speed of the poly(dT)30 transport through Si3N4 nanopores can be slowed down by half throu...The nanopore size effect on translocation of poly(dT)30through Si3N4 membrane is investigated.In this paper,we report that the speed of the poly(dT)30 transport through Si3N4 nanopores can be slowed down by half through increasing the nanopore diameter from 4.8 nm to 10.8 nm.The results are consistent with our simulation results.Besides,the current blockage induced by DNA passing through the nanopore is less obvious as pore diameter is larger,which is in good agreement with the theoretical prediction.The conclusion about DNA transport through nanopores is beneficial for the design of DNA sequencing devices.展开更多
文摘The dynamic behaviors of the keyhole and weld pool are coupled together in plasma arc welding, and the geometric variations of both the keyhole and the weld pool determine the weld quality. It is of great significance to simultaneously sense and monitor the keyhole and the weld pool behaviors by using a single low-cost vision sensor in plasma arc welding process. In this study, the keyhole and weld pool were observed and measured under different levels of welding current by using the near infrared sensing technology and the charge coupled device （CCD） sensing system. The shapes and relative position of weld pool and keyhole under different conditions were compared and analyzed. The observation results lay solid foundation for controlling weld quality and understanding the underlying process mechanisms.
文摘In this paper,for the first time,an experimental proof of concept for utilising time reversal(TR)in the acoustic regime to localise partial discharge(PD)sources was presented using a single sensor.To achieve this,an experimental setup comprising a water tank,acoustic transducers for signal transmission and reception,and 2D scanners was developed.The performance of the proposed method was evaluated across various scenarios,encompassing different PD source locations and sensor placements,barriers obstructing the line of sight between the receiving sensor and PD sources,varying levels of noise,and different frequency bandwidths for the PD sources.The experimental results demonstrate a near-zero localisation error in all considered examples.The achieved resolution was approximately half of the minimum wavelength.Furthermore,the acoustic TR method exhibits remarkable precision in source localisation,even when faced with obstacles such as a multi-layered metallic cylinder and in scenarios lacking a direct line of sight between the sensor and the source.The accuracy of acoustic TR's localisation remained robust in the presence of noise,showcasing resilience at signal-to-noise ratio levels as low as−20 dB.Additionally,the performance of the acoustic TR method remained consistent across a broad frequency spectrum,spanning from 60 to 200 kHz.
文摘A method for the multi target locating and tracking with the multi sensor in a field artillery system is studied. A general modeling structure of the system is established. Based on concepts of cluster and closed ball, an algorithm is put forward for multi sensor multi target data fusion and an optimal solution for state estimation is presented. The simulation results prove the algorithm works well for the multi stationary target locating and the multi moving target tracking under the condition of the sparse target environment. Therefore, this method can be directly applied to the field artillery C 3I system.
基金supported by projects PID2019-106211RB-I00,PID2019-105195RA-I00,and PID2021-123228NB-I00funded by MCIN/AEI/10.13039/501100011033 and projects CNS2022-135495,and TED2021-129937B-I00 funded by MCIN/AEI/10.13039/501100011033 and by the European Union NextGeneration EU/PRTR.P.Camarero thanks Comunidad de Madrid for Programa Investigo by Plan de Recuperación,Transformación y Resiliencia-Comunidad de Madrid-Ministerio de Trabajo y Economía Social de España-Unión Europea-NextGenerationEU.F.Zhang acknowledges the scholarship from the China Scholarship Council (202108440235)supported by Comunidad de Madrid (S2022/BMD-7403 RENIM-CM and REACT-UCM projects).
文摘Optical nanoparticles are nowadays one of the key elements of photonics.They do not only allow optical imaging of a plethora of systems(from cells to microelectronics),but,in many cases,they also behave as highly sensitive remote sensors.In recent years,it has been demonstrated the success of optical tweezers in isolating and manipulating individual optical nanoparticles.This has opened the door to high resolution single particle scanning and sensing.In this quickly growing field,it is now necessary to sum up what has been achieved so far to identify the appropriate system and experimental set-up required for each application.In this review article we summarize the most relevant results in the field of optical trapping of individual optical nanoparticles.After systematic bibliographic research,we identify the main families of optical nanoparticles in which optical trapping has been demonstrated.For each case,the main advances and applications have been described.Finally,we also include our critical opinion about the future of the field,identifying the challenges that we are facing.
基金We gratefully acknowledge the financial support from the National key Research and Development Program of China(Grant No.2016YFB1102201,2018YFB0406502)the key Research and Development Program of Shandong province(Grant No.2018CXGC0410,2017GGX20116 and 2018JMRH0207)+1 种基金the Young Scholars Program of Shandong University(Grant No.2015WLJH36)the 111 Project 2.0(Grant No.BP2018013).
文摘Single crystal fibers(SCF)are considered to be a combination of bulk crystals and conventional fibers,thereby possessing the stable physical and chemical properties accompanied with excellent waveguide properties.This paper gives a detailed introduction to the development history of single crystal fibers,including the evolution of the growth technique and the optimization of the growth process.Laser-heated pedestal growth(LHPG)and Micro-pulling-down(μ-PD)methods are considered to be the most widely used growth techniques for growing single crystal fibers,and the advantages of the two methods are also introduced in detail.The second part of this paper describes the characterization of single crystal fibers,including diameter fluctuation,crystal quality and optical losses.A series of cladding approaches for SCF,such as magnetron sputtering,sol-gel,liquid phase epitaxy,co-drawing LHPG,ion implantation and micro-structure cladding will be reviewed.In addition,the research status of single crystal fiber laser and single crystal fiber sensor are also summarized in view of the current research foundation.
基金supported by the National Basic Research Program of China(Grant No.2011CB707605)the Natural Science Foundation of China(Grants Nos.50925519,51003015,and 51005048)the Research Funding for the Doctor Program from China Educational Ministry(Grant No.20100092110051)
文摘The nanopore size effect on translocation of poly(dT)30through Si3N4 membrane is investigated.In this paper,we report that the speed of the poly(dT)30 transport through Si3N4 nanopores can be slowed down by half through increasing the nanopore diameter from 4.8 nm to 10.8 nm.The results are consistent with our simulation results.Besides,the current blockage induced by DNA passing through the nanopore is less obvious as pore diameter is larger,which is in good agreement with the theoretical prediction.The conclusion about DNA transport through nanopores is beneficial for the design of DNA sequencing devices.
