The inter-electrode gap(IEG) is an essential parameter for the anode shaping process in electrochemical machining(ECM) and directly affects the machining accuracy. In this paper, the IEG during the leveling process of...The inter-electrode gap(IEG) is an essential parameter for the anode shaping process in electrochemical machining(ECM) and directly affects the machining accuracy. In this paper, the IEG during the leveling process of an oval anode workpiece in counter-rotating ECM(CRECM)is investigated. The variation of the minimum IEG is analyzed theoretically, and the results indicate that rather than reaching equilibrium, the minimum IEG in CRECM expands constantly when a constant feed speed is used for the cathode tool. This IEG expansion leads to a poor localization effect and has an adverse influence on the roundness of the machined workpiece. To maintain a small constant IEG in CRECM, a variable feed speed is used for the cathode based on a fitted equation. The theoretical results show that the minimum IEG can be controlled at a small value by using an accelerated feed speed. Experiments have been conducted using a specific experimental apparatus in which the cathode tool is designed as a combined structure of two sectors and a thin sheet. By detecting the machining currents flowing through the minimum IEG, how the latter varies is obtained indirectly. The results indicate that using an accelerated feed speed is effective for controlling the IEG, thereby improving the roundness of the machined workpiece.展开更多
Ge2Sb2Te5 gap filling is one of the key processes for phase-change random access memory manufacture. Physical vapor deposition is the mainstream method of Ge2Sb2Te5 film deposition due to its advantages of film qualit...Ge2Sb2Te5 gap filling is one of the key processes for phase-change random access memory manufacture. Physical vapor deposition is the mainstream method of Ge2Sb2Te5 film deposition due to its advantages of film quality, purity, and accurate composition control. However,the conventional physical vapor deposition process cannot meet the gap- filling requirement with the critical device dimension scaling down to 90 nm or below. In this study, we find that the deposit-etch-deposit process shows better gap-filling capability and scalability than the single-step deposition process, especially at the nano-scale critical dimension. The gap-filling mechanism of the deposit-etch-deposit process was briefly discussed. We also find that re-deposition of phase-change material from via the sidewall to via the bottom by argon ion bombardment during the etch step was a key ingredient for the final good gap filling. We achieve void-free gap filling of phase-change material on the 45-nm via the two-cycle deposit-etch-deposit process. We gain a rather comprehensive insight into the mechanism of deposit-etch-deposit process and propose a potential gap-filling solution for over 45-nm technology nodes for phase-change random access memory.展开更多
Information plays various roles for supporting human activity.Its basic role is to describe objects in the world.Form of representation is first decided,then method of its processing can be defined on its basis.Thus a...Information plays various roles for supporting human activity.Its basic role is to describe objects in the world.Form of representation is first decided,then method of its processing can be defined on its basis.Thus an information processing paradigm is defined.As human activity gets more and more complicated,information also becomes more and more sophisticated.Form of representation and processing method become the more complicated.展开更多
This paper has proposed a practical method for determining the spatial distribution pattern of earthquakes by means of digital image processing and has given some calculation results. This method can overcome the arti...This paper has proposed a practical method for determining the spatial distribution pattern of earthquakes by means of digital image processing and has given some calculation results. This method can overcome the artificial arbitrariness which is usually inevitable in determining the spatial distribution of earthquakes. Meanwhile, the form of seismic gaps and the method for identifying seismic gaps have also been discussed. It should be pointed out that the method proposed in this paper is a new idea in this respect. However, this method is still unable to determine the seismic gap uniquely. In order to identify the real seismic gap, comprehensive analysis of the variation of other relevant parameters (e. g., the b-value, etc. ) should also be made. The results are as follows; Thephenomenon that an area of high seismic activity is surrounded by low seismicity areas, i. e., the seismic clustering pattern is the general form of spatial distribution of earthquakes; whereas a low seismicity area surrounded by high seismicity areas, i. e., the seismic gap pattern, is only an important form of spatial distribution of earthquakes. Earthquakes often occur in a certain seismic clustering area or on its margin.展开更多
In counter-rotating electrochemical machining （CRECM）, a revolving cathode tool with hollow windows of various shapes is used to fabricate convex structures on a revolving part. During this process, the anode workpi...In counter-rotating electrochemical machining （CRECM）, a revolving cathode tool with hollow windows of various shapes is used to fabricate convex structures on a revolving part. During this process, the anode workpiece and the cathode tool rotate relative to each other at the same rotation speed. In contrast to the conventional schemes of ECM machining with linear motion of a block tool electrode, this scheme of ECM is unique, and has not been adequately studied yet. In this paper, the finite element method （FEM） is used to simulate the anode shaping process during CRECM, and the simulation process which involves a meshing model, a moving boundary, and a simulation algorithm is described. The simulated anode profiles of the convex structure at different processing times show that the CRECM process can be used to fabricate convex structures of various shapes with different heights. Besides, the variation of the inter-electrode gap indicates that this process can also reach a relative equilibrium state like that in conventional ECM. A rectangular convex and a circular convex are successfully fabricated on revolving parts. The experimental results indicate relatively good agreement with the simulation results. The proposed simulation process is valid for convex shaping prediction and feasibility studies as well.展开更多
The Tahiti-Darwin Southern Oscillation index provided by Climate Analysis Center of USA has been used in numerous studies. But, it has some deficiency. It contains noise mainly due to high month-to-month variability. ...The Tahiti-Darwin Southern Oscillation index provided by Climate Analysis Center of USA has been used in numerous studies. But, it has some deficiency. It contains noise mainly due to high month-to-month variability. In order to reduce the level of noise in the SO index, this paper introduces a fully data-adaptive filter based on singular spectrum analysis. Another interesting aspect of the filter is that it can be used to fill data gaps of the SO index by an iterative process. Eventually, a noiseless long-period data series without any gaps is obtained.展开更多
In order to reduce the test samples in the reliability design and assessment,the function process of air-gap detonation transfer interface was simulated by LS-DYNA software.The stress nephograms for the detonation tra...In order to reduce the test samples in the reliability design and assessment,the function process of air-gap detonation transfer interface was simulated by LS-DYNA software.The stress nephograms for the detonation transfer processes of six kinds of design parameters were analyzed.The results show that when the length of air-gap is between 2 and 18 mm,the detonation can be normally transferred which is consistent with the test result of NeyerD method.The result has referential value for design and analysis of similar products.展开更多
基金supported by the National Natural Science Foundation of China (51535006, 51805259)Natural Science Foundation of Jiangsu Province of China (BK20180431)+2 种基金Fundamental Research Funds for the Central Universities of China (3082018NP2018406)Young Elite Scientists Sponsorship Program by CAST of ChinaJiangsu Key Laboratory of Precision and Micro-Manufacturing Technology of China
文摘The inter-electrode gap(IEG) is an essential parameter for the anode shaping process in electrochemical machining(ECM) and directly affects the machining accuracy. In this paper, the IEG during the leveling process of an oval anode workpiece in counter-rotating ECM(CRECM)is investigated. The variation of the minimum IEG is analyzed theoretically, and the results indicate that rather than reaching equilibrium, the minimum IEG in CRECM expands constantly when a constant feed speed is used for the cathode tool. This IEG expansion leads to a poor localization effect and has an adverse influence on the roundness of the machined workpiece. To maintain a small constant IEG in CRECM, a variable feed speed is used for the cathode based on a fitted equation. The theoretical results show that the minimum IEG can be controlled at a small value by using an accelerated feed speed. Experiments have been conducted using a specific experimental apparatus in which the cathode tool is designed as a combined structure of two sectors and a thin sheet. By detecting the machining currents flowing through the minimum IEG, how the latter varies is obtained indirectly. The results indicate that using an accelerated feed speed is effective for controlling the IEG, thereby improving the roundness of the machined workpiece.
基金Project supported by the National Basic Research Program of China (Grant Nos.2010CB934300,2011CBA00607,and 2011CB932800)the National Integrate Circuit Research Program of China (Grant No. 2009ZX02023-003)+1 种基金the National Natural Science Foundation of China (Grant Nos. 60906004,60906003,61006087,and 61076121)the Science and Technology Council of Shanghai,China (Grant No. 1052nm07000)
文摘Ge2Sb2Te5 gap filling is one of the key processes for phase-change random access memory manufacture. Physical vapor deposition is the mainstream method of Ge2Sb2Te5 film deposition due to its advantages of film quality, purity, and accurate composition control. However,the conventional physical vapor deposition process cannot meet the gap- filling requirement with the critical device dimension scaling down to 90 nm or below. In this study, we find that the deposit-etch-deposit process shows better gap-filling capability and scalability than the single-step deposition process, especially at the nano-scale critical dimension. The gap-filling mechanism of the deposit-etch-deposit process was briefly discussed. We also find that re-deposition of phase-change material from via the sidewall to via the bottom by argon ion bombardment during the etch step was a key ingredient for the final good gap filling. We achieve void-free gap filling of phase-change material on the 45-nm via the two-cycle deposit-etch-deposit process. We gain a rather comprehensive insight into the mechanism of deposit-etch-deposit process and propose a potential gap-filling solution for over 45-nm technology nodes for phase-change random access memory.
文摘Information plays various roles for supporting human activity.Its basic role is to describe objects in the world.Form of representation is first decided,then method of its processing can be defined on its basis.Thus an information processing paradigm is defined.As human activity gets more and more complicated,information also becomes more and more sophisticated.Form of representation and processing method become the more complicated.
文摘This paper has proposed a practical method for determining the spatial distribution pattern of earthquakes by means of digital image processing and has given some calculation results. This method can overcome the artificial arbitrariness which is usually inevitable in determining the spatial distribution of earthquakes. Meanwhile, the form of seismic gaps and the method for identifying seismic gaps have also been discussed. It should be pointed out that the method proposed in this paper is a new idea in this respect. However, this method is still unable to determine the seismic gap uniquely. In order to identify the real seismic gap, comprehensive analysis of the variation of other relevant parameters (e. g., the b-value, etc. ) should also be made. The results are as follows; Thephenomenon that an area of high seismic activity is surrounded by low seismicity areas, i. e., the seismic clustering pattern is the general form of spatial distribution of earthquakes; whereas a low seismicity area surrounded by high seismicity areas, i. e., the seismic gap pattern, is only an important form of spatial distribution of earthquakes. Earthquakes often occur in a certain seismic clustering area or on its margin.
基金supported by the Program for New Century Excellent Talents in University of China(NCET-10-0074)
文摘In counter-rotating electrochemical machining （CRECM）, a revolving cathode tool with hollow windows of various shapes is used to fabricate convex structures on a revolving part. During this process, the anode workpiece and the cathode tool rotate relative to each other at the same rotation speed. In contrast to the conventional schemes of ECM machining with linear motion of a block tool electrode, this scheme of ECM is unique, and has not been adequately studied yet. In this paper, the finite element method （FEM） is used to simulate the anode shaping process during CRECM, and the simulation process which involves a meshing model, a moving boundary, and a simulation algorithm is described. The simulated anode profiles of the convex structure at different processing times show that the CRECM process can be used to fabricate convex structures of various shapes with different heights. Besides, the variation of the inter-electrode gap indicates that this process can also reach a relative equilibrium state like that in conventional ECM. A rectangular convex and a circular convex are successfully fabricated on revolving parts. The experimental results indicate relatively good agreement with the simulation results. The proposed simulation process is valid for convex shaping prediction and feasibility studies as well.
文摘The Tahiti-Darwin Southern Oscillation index provided by Climate Analysis Center of USA has been used in numerous studies. But, it has some deficiency. It contains noise mainly due to high month-to-month variability. In order to reduce the level of noise in the SO index, this paper introduces a fully data-adaptive filter based on singular spectrum analysis. Another interesting aspect of the filter is that it can be used to fill data gaps of the SO index by an iterative process. Eventually, a noiseless long-period data series without any gaps is obtained.
基金Joint Funds of ational Natural Science Foundation of China(No.U1530135)
文摘In order to reduce the test samples in the reliability design and assessment,the function process of air-gap detonation transfer interface was simulated by LS-DYNA software.The stress nephograms for the detonation transfer processes of six kinds of design parameters were analyzed.The results show that when the length of air-gap is between 2 and 18 mm,the detonation can be normally transferred which is consistent with the test result of NeyerD method.The result has referential value for design and analysis of similar products.
