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On the COF (chip on film) substrate, the width of the conductor of substrate is usually smaller than 50μm and with the smallest ones being 15μm. It is difficult to produce it by conventional subtractive process. In this study, t...
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On the COF (chip on film) substrate, the width of the conductor of substrate is usually smaller than 50μm and with the smallest ones being 15μm. It is difficult to produce it by conventional subtractive process. In this study, the semi-additive process has been used to produce fine pitch substrate of COF. The FCCL (flexible copper clad laminate) used in the semi-additive process is a copper foil that is 2μm thick, compare to the FCCL with 8μm thick copper foil is used to produce the same substrate of COF by conventional subtractive process. The effects of semi-additive process and subtractive process have been studied and compared. Two sample substrates (50μm /50μm and 30μm /30μm fine pitch) have been designed. H2SO4/H2O2 etchant has been used in etching process for the semi-additive process successfully. The test results of the metallographic slicing tester and the SEM show that semi-additive process is more suitable to produce fine pitch pattern (below 50μm/50μm) than Subtractive process, especially in the application that requires an accurate impedance. In addition, the periodic pulse reverse plating can improve the thickness uniformity and physical properties of electroplating copper layer.
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The plasma desmear process is one of the crucial problems in the manufacture of rigid-flex printed circuit boards (PCB). The technological parameters of the plasma desmear process for rigid-flex PCBs were optimized by an orthogona...
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The plasma desmear process is one of the crucial problems in the manufacture of rigid-flex printed circuit boards (PCB). The technological parameters of the plasma desmear process for rigid-flex PCBs were optimized by an orthogonal experiment design (OED). Minitab Statistical Analysis Software was used to obtain a nonlinear regression analysis for the data obtained from the orthogonal experiment. Prediction and control for production had been realized by the regression equation. A four-layer high density interconnect (HDI) rigid-flex PCB was developed successfully and the qualification rate reached 92% under the optimum conditions for the plasma desmear process.
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Trajectory distribution of vessels shares a large difference between coastal waters and exposed waters, thus a segment algorithm is needed when mining the waterway patterns to analysis the traffic flow. Considering traditional spa...
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Trajectory distribution of vessels shares a large difference between coastal waters and exposed waters, thus a segment algorithm is needed when mining the waterway patterns to analysis the traffic flow. Considering traditional spatiotemporal trajectory cluster algorithm cannot meet the requirements on big data processing speed, this paper proposes a wavelet clustering-based vessel channel pattern extraction algorithm. Firstly, a marine navigation feature space is built by means of dividing the target area into grids, which is transformed into a transform domain using two-dimensional discrete wavelet transform algorithm in the next step. Then we select an appropriate threshold to find the connected region and sub-regions with different density distributions are obtained. Drawing on the idea of image processing, this algorithm takes the channel boundary and distribution matrix as the overall channel characteristics. In the end, real historical AIS data is used to verify the method. The results show that such can reduce the processing complexity of spatiotemporal trajectory data, and greatly shorten the response time to find vessel channel patterns.
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摘要 :
Trajectory distribution of vessels shares a large difference between coastal waters and exposed waters, thus a segment algorithm is needed when mining the waterway patterns to analysis the traffic flow. Considering traditional spa...
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Trajectory distribution of vessels shares a large difference between coastal waters and exposed waters, thus a segment algorithm is needed when mining the waterway patterns to analysis the traffic flow. Considering traditional spatiotemporal trajectory cluster algorithm cannot meet the requirements on big data processing speed, this paper proposes a wavelet clustering-based vessel channel pattern extraction algorithm. Firstly, a marine navigation feature space is built by means of dividing the target area into grids, which is transformed into a transform domain using two-dimensional discrete wavelet transform algorithm in the next step. Then we select an appropriate threshold to find the connected region and sub-regions with different density distributions are obtained. Drawing on the idea of image processing, this algorithm takes the channel boundary and distribution matrix as the overall channel characteristics. In the end, real historical AIS data is used to verify the method. The results show that such can reduce the processing complexity of spatiotemporal trajectory data, and greatly shorten the response time to find vessel channel patterns.
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In this paper, a discontinuous spectra orthogonal discrete frequency-coding waveform (DFCW) set design method for MIMO sky-wave radar is proposed. The usable discontinuous spectra is divided to a discrete frequency coding accordin...
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In this paper, a discontinuous spectra orthogonal discrete frequency-coding waveform (DFCW) set design method for MIMO sky-wave radar is proposed. The usable discontinuous spectra is divided to a discrete frequency coding according to suitable sub-pulse bandwidth, Taking minimum of weighted sum of the sidelobe peaks of autocorrelation function (ACF), the peaks of cross-correlation function (CCF) and resolutions for DFCW as objective function, the frequency firing combination and order as variables to be optimized, a mathematical model for discontinuous spectra DFCW design is established. The problem is solved by quantum-behaved particle swarm optimization (QPSO) algorithm. Numerical simulation verified the effectiveness of the method of the design of DFCWs.
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摘要 :
In this paper, a discontinuous spectra orthogonal discrete frequency-coding waveform (DFCW) set design method for MIMO sky-wave radar is proposed. The usable discontinuous spectra is divided to a discrete frequency coding accordin...
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In this paper, a discontinuous spectra orthogonal discrete frequency-coding waveform (DFCW) set design method for MIMO sky-wave radar is proposed. The usable discontinuous spectra is divided to a discrete frequency coding according to suitable sub-pulse bandwidth, Taking minimum of weighted sum of the sidelobe peaks of autocorrelation function (ACF), the peaks of cross-correlation function (CCF) and resolutions for DFCW as objective function, the frequency firing combination and order as variables to be optimized, a mathematical model for discontinuous spectra DFCW design is established. The problem is solved by quantum-behaved particle swarm optimization(QPSO) algorithm. Numerical simulation verified the effectiveness of the method of the design of DFCWs.
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摘要 :
In this paper, a discontinuous spectra orthogonal discrete frequency-coding waveform (DFCW) set design method for MIMO sky-wave radar is proposed. The usable discontinuous spectra is divided to a discrete frequency coding accordin...
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In this paper, a discontinuous spectra orthogonal discrete frequency-coding waveform (DFCW) set design method for MIMO sky-wave radar is proposed. The usable discontinuous spectra is divided to a discrete frequency coding according to suitable sub-pulse bandwidth, Taking minimum of weighted sum of the sidelobe peaks of autocorrelation function (ACF), the peaks of cross-correlation function (CCF) and resolutions for DFCW as objective function, the frequency firing combination and order as variables to be optimized, a mathematical model for discontinuous spectra DFCW design is established. The problem is solved by quantum-behaved particle swarm optimization(QPSO) algorithm. Numerical simulation verified the effectiveness of the method of the design of DFCWs.
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Analysis of the structure characteristics of the General Hospital of Fuxin Mining Group, through the instrument observation and use the finite element software for structural modeling, modal analysis show that the quality of struc...
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Analysis of the structure characteristics of the General Hospital of Fuxin Mining Group, through the instrument observation and use the finite element software for structural modeling, modal analysis show that the quality of structural system, the stiffness is more evenly distributed the structure of the torsional capacity to meet the requirements. Through input into Tianjin wave, analysis the dynamic characteristics of the model, the results show that: to tall wall-frame structure, shear wall is very restriction of lateral displacement in the central and bottom, stronger than upper structure on lateral displacement limit ability.
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摘要 :
Analysis of the structure characteristics of the General Hospital of Fuxin Mining Group, through the instrument observation and use the finite element software for structural modeling, modal analysis show that the quality of struc...
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Analysis of the structure characteristics of the General Hospital of Fuxin Mining Group, through the instrument observation and use the finite element software for structural modeling, modal analysis show that the quality of structural system, the stiffness is more evenly distributed the structure of the torsional capacity to meet the requirements. Through input into Tianjin wave, analysis the dynamic characteristics of the model, the results show that: to tall wall-frame structure, shear wall is very restriction of lateral displacement in the central and bottom, stronger than upper structure on lateral displacement limit ability.
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A new simulation method for sky-wave OHTR ionospheric channels is developed. To make the simulation more robust, the International Geomagnetic Reference Field (IGRF) model and International Reference Ionosphere (IRI) model are int...
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A new simulation method for sky-wave OHTR ionospheric channels is developed. To make the simulation more robust, the International Geomagnetic Reference Field (IGRF) model and International Reference Ionosphere (IRI) model are integrated with a classical 3D ray tracing code firstly. After numerical ray tracing, a new algorithm for matching outbound raypaths with returning raypaths is developed. The channel simulation is established with the consideration of the Doppler-space-delay correlation. Stochastic channel generated by this simulation can be used for OTHR design and signal processing research.
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