Plasma spraying is an important enabling technology i n near-net-shaped process as well as many high-performance coating applicatio ns. Recently, it is being applied to rapid mould manufacturing to reduce develop ment...Plasma spraying is an important enabling technology i n near-net-shaped process as well as many high-performance coating applicatio ns. Recently, it is being applied to rapid mould manufacturing to reduce develop ment time and manufacturing cost. In this process, inputted powders are heated a nd accelerated by plasma jet, and impinge on master pattern or prototype to form ing a thick coating. Mould will be fabricated after backed-up with consolidated material and other post-treatments. Amongst numerous factors that affect the l ife and properties of mould made by this novel method, quality of coating is the most important one. However, the complex nature of the spray process results in a large number of processing parameters that must be controlled in order to obt ain optimum coatings. Traditional "trial and error" method is too time and cost consuming for the optimal processing parameters. Maybe modeling and diagnostics of process is the best way to ravel out the problems. It has been proved that pl asma-gas flowrate, power level and spray distance are the most critical variabl es. So flow visualization and diagnostics for plasma jet quality has become an i mportant task to obtain a repeatable and reliable plasma processing technology. Using enthalpy probe diagnostics, spectrometry and optical measurement, we can o btain the distribution of temperature field of plasma jet. These results can hel p us to design gun configuration and optimize processing parameters for high dep osition efficiency and good qualities of rapid mould manufacturing. Nevertheless , it is still very difficult to realize real-time diagnoses because of restrict of diagnosis condition and drawback of measurement approach. In our researches, a real-time data collection and image processing system for plasma jet with high temperature, velocity and compressed energy has been realiz ed by CCD sensor. In this paper, we firstly focus our attention on collection pr inciple and methods, and an effective method for collecting data in high tempera ture area is presented. Then a system of real-time data collection by CCD camer a is developed. Finally, fake color image processing is given to analyze the law of temperature field distribution under different conditions. The results are i mportant to realize the visualization of plasma spraying, and especially to furt her study on closed-loop feedback control of forming quality for plasma rapid m anufacturing process.展开更多
A measurement system for the scattering characteristics of warhead fragments based on high-speed imaging systems offers advantages such as simple deployment,flexible maneuverability,and high spatiotemporal resolution,...A measurement system for the scattering characteristics of warhead fragments based on high-speed imaging systems offers advantages such as simple deployment,flexible maneuverability,and high spatiotemporal resolution,enabling the acquisition of full-process data of the fragment scattering process.However,mismatches between camera frame rates and target velocities can lead to long motion blur tails of high-speed fragment targets,resulting in low signal-to-noise ratios and rendering conventional detection algorithms ineffective in dynamic strong interference testing environments.In this study,we propose a detection framework centered on dynamic strong interference disturbance signal separation and suppression.We introduce a mixture Gaussian model constrained under a joint spatialtemporal-transform domain Dirichlet process,combined with total variation regularization to achieve disturbance signal suppression.Experimental results demonstrate that the proposed disturbance suppression method can be integrated with certain conventional motion target detection tasks,enabling adaptation to real-world data to a certain extent.Moreover,we provide a specific implementation of this process,which achieves a detection rate close to 100%with an approximate 0%false alarm rate in multiple sets of real target field test data.This research effectively advances the development of the field of damage parameter testing.展开更多
The design of experimental system of digital imaging system for control parameter is discussed in detail. Signal processing of digital CCD imaging system is first analyzed. Then the real time control of CCD driver and...The design of experimental system of digital imaging system for control parameter is discussed in detail. Signal processing of digital CCD imaging system is first analyzed. Then the real time control of CCD driver and digital processing circuit and man-machine interaction are achieved by the design of digital CCD imaging module and control module. Experimental results indicate that the image quality of CCD experimental system makes a good response to the change of control parameters. The system gives an important base for improving image quality and the applicability of micro imaging system in complex environment.展开更多
文摘Plasma spraying is an important enabling technology i n near-net-shaped process as well as many high-performance coating applicatio ns. Recently, it is being applied to rapid mould manufacturing to reduce develop ment time and manufacturing cost. In this process, inputted powders are heated a nd accelerated by plasma jet, and impinge on master pattern or prototype to form ing a thick coating. Mould will be fabricated after backed-up with consolidated material and other post-treatments. Amongst numerous factors that affect the l ife and properties of mould made by this novel method, quality of coating is the most important one. However, the complex nature of the spray process results in a large number of processing parameters that must be controlled in order to obt ain optimum coatings. Traditional "trial and error" method is too time and cost consuming for the optimal processing parameters. Maybe modeling and diagnostics of process is the best way to ravel out the problems. It has been proved that pl asma-gas flowrate, power level and spray distance are the most critical variabl es. So flow visualization and diagnostics for plasma jet quality has become an i mportant task to obtain a repeatable and reliable plasma processing technology. Using enthalpy probe diagnostics, spectrometry and optical measurement, we can o btain the distribution of temperature field of plasma jet. These results can hel p us to design gun configuration and optimize processing parameters for high dep osition efficiency and good qualities of rapid mould manufacturing. Nevertheless , it is still very difficult to realize real-time diagnoses because of restrict of diagnosis condition and drawback of measurement approach. In our researches, a real-time data collection and image processing system for plasma jet with high temperature, velocity and compressed energy has been realiz ed by CCD sensor. In this paper, we firstly focus our attention on collection pr inciple and methods, and an effective method for collecting data in high tempera ture area is presented. Then a system of real-time data collection by CCD camer a is developed. Finally, fake color image processing is given to analyze the law of temperature field distribution under different conditions. The results are i mportant to realize the visualization of plasma spraying, and especially to furt her study on closed-loop feedback control of forming quality for plasma rapid m anufacturing process.
文摘A measurement system for the scattering characteristics of warhead fragments based on high-speed imaging systems offers advantages such as simple deployment,flexible maneuverability,and high spatiotemporal resolution,enabling the acquisition of full-process data of the fragment scattering process.However,mismatches between camera frame rates and target velocities can lead to long motion blur tails of high-speed fragment targets,resulting in low signal-to-noise ratios and rendering conventional detection algorithms ineffective in dynamic strong interference testing environments.In this study,we propose a detection framework centered on dynamic strong interference disturbance signal separation and suppression.We introduce a mixture Gaussian model constrained under a joint spatialtemporal-transform domain Dirichlet process,combined with total variation regularization to achieve disturbance signal suppression.Experimental results demonstrate that the proposed disturbance suppression method can be integrated with certain conventional motion target detection tasks,enabling adaptation to real-world data to a certain extent.Moreover,we provide a specific implementation of this process,which achieves a detection rate close to 100%with an approximate 0%false alarm rate in multiple sets of real target field test data.This research effectively advances the development of the field of damage parameter testing.
基金the National "863" Program Project of China(2002AA742061)
文摘The design of experimental system of digital imaging system for control parameter is discussed in detail. Signal processing of digital CCD imaging system is first analyzed. Then the real time control of CCD driver and digital processing circuit and man-machine interaction are achieved by the design of digital CCD imaging module and control module. Experimental results indicate that the image quality of CCD experimental system makes a good response to the change of control parameters. The system gives an important base for improving image quality and the applicability of micro imaging system in complex environment.
