Based on genetic algorithm and neural network algorithm,the finite element analyses on the temperature fields and stress fields of multi-track laser cladding were carried out by using the ANSYS software.The results sh...Based on genetic algorithm and neural network algorithm,the finite element analyses on the temperature fields and stress fields of multi-track laser cladding were carried out by using the ANSYS software.The results show that,in the multi-track cladding process,the temperature field ellipse leans to the cladding formed,and the front cladding has preheating function on the following cladding.During cladding,the longitudinal stress is the largest,the lateral stress is the second,and the thickness direction stress is the smallest.The center of the cladding is in the tensile stress condition.The longitudinal tensile stress is higher than the lateral or thickness direction stress by several times,and the tensile stress achieves the maximum at the area of joint between the cladding and substrate.Therefore,it is inferred that transversal crack is the most main crack form in multi-track laser cladding.Moreover,the joint between cladding and substrate is the crack sensitive area,and this is consistent with the actual experiments.展开更多
Laser directed energy deposition(DED)involves complex physical processes,and the trial and error examinations are time consuming and cost expensive.The research paradigm can be reshaped using advanced phenomenological...Laser directed energy deposition(DED)involves complex physical processes,and the trial and error examinations are time consuming and cost expensive.The research paradigm can be reshaped using advanced phenomenological models via computing the spatiotemporal variations of the build features.In this work,multi-layer and multi-track laser DED of Ti-6 Al-4 V were systematically explored on multiple scales including the 1D track,the 2D layer and the 3D full build considering the complex transport of energy,mass,and momentum in the moving freeform molten pool.The results showed that convex,nearflat,and wavy builds were generated using gradually larger hatch spacings.The profiles of individual tracks and layers were extracted through the unique advantages of the model.The individual tracks exhibited various patterns and rotated with specific inclinations to form distinct layer profiles.The net increments of the deposit generated upon the printing of a new track during the continuous deposition process showed that the smaller hatch spacing caused higher overlap rate of horizontally adjacent tracks but lower remelting rate of vertically adjacent tracks in neighboring layers.The 3D numerical model was validated with corresponding experiments for various process conditions.The scientific findings can provide useful insights for further researches of DED.展开更多
To improve the efficiency and accuracy of single-event effect(SEE)research at the Heavy Ion Research Facility at Lanzhou,Hi’Beam-SEE must precisely localize the position at which each heavy ion hitting the integrated...To improve the efficiency and accuracy of single-event effect(SEE)research at the Heavy Ion Research Facility at Lanzhou,Hi’Beam-SEE must precisely localize the position at which each heavy ion hitting the integrated circuit(IC)causes SEE.In this study,we propose a fast multi-track location(FML)method based on deep learning to locate the position of each particle track with high speed and accuracy.FML can process a vast amount of data supplied by Hi’Beam-SEE online,revealing sensitive areas in real time.FML is a slot-based object-centric encoder-decoder structure in which each slot can learn the location information of each track in the image.To make the method more accurate for real data,we designed an algorithm to generate a simulated dataset with a distribution similar to that of the real data,which was then used to train the model.Extensive comparison experiments demonstrated that the FML method,which has the best performance on simulated datasets,has high accuracy on real datasets as well.In particular,FML can reach 238 fps and a standard error of 1.6237μm.This study discusses the design and performance of FML.展开更多
A new inorganic-organic hybrid constructed from α-octamolybdate polyoxometalates modified by hexad- track Cu―bpe chains, 2{[Cu（bpe）]6[α-Mo8O26]3/2}·[Cu（bpe）]3·3H2O[1, bpe=bis（4-pyridyl）ethylene], ha...A new inorganic-organic hybrid constructed from α-octamolybdate polyoxometalates modified by hexad- track Cu―bpe chains, 2{[Cu（bpe）]6[α-Mo8O26]3/2}·[Cu（bpe）]3·3H2O[1, bpe=bis（4-pyridyl）ethylene], has been synthesized and structurally characterized. X-Ray diffraction analysis reveals that each α-octamolybdate cluster links six transition metal complex chains and the title compound has represented the highest connective number of M―N chains modified octamolybdate POMs to date. Note that there are two crystallographically unique [α-Mo8O26]n- clusters and eight unique copper sites, which play an important role in the overall architecture of hybrid compounds. Additionally, the electrochemical properties of the title compound were studied.展开更多
Laser directed energy deposition(DED)is a multi-physics process that accompanies mass flow,energy transfer,and complex phase transitions.The printing characteristics of small size parts are significantly affected by t...Laser directed energy deposition(DED)is a multi-physics process that accompanies mass flow,energy transfer,and complex phase transitions.The printing characteristics of small size parts are significantly affected by the progressive variations of the temperature fields and the fluid flow within the molten pool.In this work,the deposition characteristics during multi-layer and multi-track laser DED were explored through a well-tested phenomenological model and corresponding experimental results.The variations of the build profiles and the decoupled track and layer profiles were systematically examined.Moreover,the printing characteristics of the builds with different scanning lengths were compared.Results showed that the multi-layer and multi-track transient deposition processes generated a significantly wavy surface profile.Compared with the long scanning length part,the beginning region of the short build produced an obvious bulge followed by sharply decreased height along the scanning direction.The transverse section of the short build varied significantly at different positions.Two adjacent columns of tracks were extracted from the overall build,demonstrating that the tracks tilted outwards and the angle increases along the scanning direction.The 3D numerical model was validated with corresponding experiments for builds with various layers.The scientific findings from this work can provide useful insights for the understanding of the additive mechanisms during laser DED for the precise shape control of small size parts.展开更多
Bit-Pattemed Magnetic Recording(BPMR)is one of the emerging data storage technologies,which promises an Areal Density(AD)of about 4 Tb/in2.However,a major problem practically encountered in a BPMR system is Inter-Trac...Bit-Pattemed Magnetic Recording(BPMR)is one of the emerging data storage technologies,which promises an Areal Density(AD)of about 4 Tb/in2.However,a major problem practically encountered in a BPMR system is Inter-Track Interference(ITI)that can deteriorate the overall system performance,especially at high ADs.This paper proposes an iterative ITI cancellation method for an m-head m-track BPMR system,which uses m heads to read m adjacent tracks and decodes them simultaneously.To cancel the ITI,we subtract the weighted readback signals of adjacent tracks,acting as the ITI signals,from the readback signal of the target track,before passing the refined readback signal to a turbo decoder.Then,the decoded data will be employed to reconstruct the ITI signal for the next turbo iteration.Experimental results indicate that the proposed system performs better than the conventional system that uses one head to read one data track.Furthermore,we also find out that the proposed system is more robust to media noise and track misregistration than the conventional system.展开更多
基金Project(HIT(WH)200711)supported by the Study Fund of Harbin Institute of Technology at Weihai,China。
文摘Based on genetic algorithm and neural network algorithm,the finite element analyses on the temperature fields and stress fields of multi-track laser cladding were carried out by using the ANSYS software.The results show that,in the multi-track cladding process,the temperature field ellipse leans to the cladding formed,and the front cladding has preheating function on the following cladding.During cladding,the longitudinal stress is the largest,the lateral stress is the second,and the thickness direction stress is the smallest.The center of the cladding is in the tensile stress condition.The longitudinal tensile stress is higher than the lateral or thickness direction stress by several times,and the tensile stress achieves the maximum at the area of joint between the cladding and substrate.Therefore,it is inferred that transversal crack is the most main crack form in multi-track laser cladding.Moreover,the joint between cladding and substrate is the crack sensitive area,and this is consistent with the actual experiments.
基金The National Key Research and Development Program of China(No.2017YFB1103000)The National Natural Science Foundation of China(No.51805267)+1 种基金The Natural Science Foundation of Jiangsu Province(No.BK20180483)the fund of the State Key Laboratory of Solidification Processing in NWPU(No.SKLSP201830)。
文摘Laser directed energy deposition(DED)involves complex physical processes,and the trial and error examinations are time consuming and cost expensive.The research paradigm can be reshaped using advanced phenomenological models via computing the spatiotemporal variations of the build features.In this work,multi-layer and multi-track laser DED of Ti-6 Al-4 V were systematically explored on multiple scales including the 1D track,the 2D layer and the 3D full build considering the complex transport of energy,mass,and momentum in the moving freeform molten pool.The results showed that convex,nearflat,and wavy builds were generated using gradually larger hatch spacings.The profiles of individual tracks and layers were extracted through the unique advantages of the model.The individual tracks exhibited various patterns and rotated with specific inclinations to form distinct layer profiles.The net increments of the deposit generated upon the printing of a new track during the continuous deposition process showed that the smaller hatch spacing caused higher overlap rate of horizontally adjacent tracks but lower remelting rate of vertically adjacent tracks in neighboring layers.The 3D numerical model was validated with corresponding experiments for various process conditions.The scientific findings can provide useful insights for further researches of DED.
基金supported by the National Natural Science Foundation of China (Nos.U2032209,11975292,12222512)the National Key Research and Development Program of China (2021YFA1601300)+2 种基金the CAS“Light of West China”Programthe CAS Pioneer Hundred Talent Programthe Guangdong Major Project of Basic and Applied Basic Research (No.2020B0301030008)。
文摘To improve the efficiency and accuracy of single-event effect(SEE)research at the Heavy Ion Research Facility at Lanzhou,Hi’Beam-SEE must precisely localize the position at which each heavy ion hitting the integrated circuit(IC)causes SEE.In this study,we propose a fast multi-track location(FML)method based on deep learning to locate the position of each particle track with high speed and accuracy.FML can process a vast amount of data supplied by Hi’Beam-SEE online,revealing sensitive areas in real time.FML is a slot-based object-centric encoder-decoder structure in which each slot can learn the location information of each track in the image.To make the method more accurate for real data,we designed an algorithm to generate a simulated dataset with a distribution similar to that of the real data,which was then used to train the model.Extensive comparison experiments demonstrated that the FML method,which has the best performance on simulated datasets,has high accuracy on real datasets as well.In particular,FML can reach 238 fps and a standard error of 1.6237μm.This study discusses the design and performance of FML.
基金Supported by the National Natural Science Foundation of China(Nos.20901031 and 21071029)the Natural Science Foundation of Heilongjiang Province+4 种基金China(No.B200916)the Education Ministry Key Teachers Foundation of Heilongjiang ProvinceChina(No.1155G53)the Talent Training Fund of Jiamusi University China(No.RC2009-034)
文摘A new inorganic-organic hybrid constructed from α-octamolybdate polyoxometalates modified by hexad- track Cu―bpe chains, 2{[Cu（bpe）]6[α-Mo8O26]3/2}·[Cu（bpe）]3·3H2O[1, bpe=bis（4-pyridyl）ethylene], has been synthesized and structurally characterized. X-Ray diffraction analysis reveals that each α-octamolybdate cluster links six transition metal complex chains and the title compound has represented the highest connective number of M―N chains modified octamolybdate POMs to date. Note that there are two crystallographically unique [α-Mo8O26]n- clusters and eight unique copper sites, which play an important role in the overall architecture of hybrid compounds. Additionally, the electrochemical properties of the title compound were studied.
基金the Development of a Verification Platform for Product Design,Process,and Information Exchange Standards in Additive Manufacturing(No.2019-00899-1-1)the National Natural Science Foundation of China(No.51805267)+2 种基金the Natural Science Foundation of Jiangsu Province(No.BK20180483)the Fundamental Research Funds for the Central Universities(No.30921011202)the fund of the State Key Laboratory of Solidification Processing in NWPU(No.SKLSP201830)。
文摘Laser directed energy deposition(DED)is a multi-physics process that accompanies mass flow,energy transfer,and complex phase transitions.The printing characteristics of small size parts are significantly affected by the progressive variations of the temperature fields and the fluid flow within the molten pool.In this work,the deposition characteristics during multi-layer and multi-track laser DED were explored through a well-tested phenomenological model and corresponding experimental results.The variations of the build profiles and the decoupled track and layer profiles were systematically examined.Moreover,the printing characteristics of the builds with different scanning lengths were compared.Results showed that the multi-layer and multi-track transient deposition processes generated a significantly wavy surface profile.Compared with the long scanning length part,the beginning region of the short build produced an obvious bulge followed by sharply decreased height along the scanning direction.The transverse section of the short build varied significantly at different positions.Two adjacent columns of tracks were extracted from the overall build,demonstrating that the tracks tilted outwards and the angle increases along the scanning direction.The 3D numerical model was validated with corresponding experiments for builds with various layers.The scientific findings from this work can provide useful insights for the understanding of the additive mechanisms during laser DED for the precise shape control of small size parts.
基金This work was supported by Research and Development Institute,Nakhon Pathom Rajabhat University,Thailand,under Grant GP_6212.
文摘Bit-Pattemed Magnetic Recording(BPMR)is one of the emerging data storage technologies,which promises an Areal Density(AD)of about 4 Tb/in2.However,a major problem practically encountered in a BPMR system is Inter-Track Interference(ITI)that can deteriorate the overall system performance,especially at high ADs.This paper proposes an iterative ITI cancellation method for an m-head m-track BPMR system,which uses m heads to read m adjacent tracks and decodes them simultaneously.To cancel the ITI,we subtract the weighted readback signals of adjacent tracks,acting as the ITI signals,from the readback signal of the target track,before passing the refined readback signal to a turbo decoder.Then,the decoded data will be employed to reconstruct the ITI signal for the next turbo iteration.Experimental results indicate that the proposed system performs better than the conventional system that uses one head to read one data track.Furthermore,we also find out that the proposed system is more robust to media noise and track misregistration than the conventional system.
