In the commercial utilization of rigid ceramic filters, the performance of pulse cleaning has crucial effects on the long-term stable operation. In order to get a clear insight into the nature of this cleaning process...In the commercial utilization of rigid ceramic filters, the performance of pulse cleaning has crucial effects on the long-term stable operation. In order to get a clear insight into the nature of this cleaning process and provide a solid basis for industrial applications, the flow in ceramic candle filter was investigated. The flow in the pulse-jetspace and inside the ceramic candle is regarded as two- dimensional, unsteady, compressible flow, and numerical simulation is carried out by computational fluid dynamics. The numerical predictions of flow field are in good agreement with the experimental measurements. Effects of the candle diameter, the separation distance between the nozzle and the candle injector and the length of the candle on the flowfield have been numerically analyzed to provide the basis for the optimum design of the pulse cleaning system.展开更多
This paper presents an analog circuit built-in-test （BIT） structure based on boundary scan and realizes the BI＇I. It predigests the test process and improves the test precision by taking the rectangular pulse as st...This paper presents an analog circuit built-in-test （BIT） structure based on boundary scan and realizes the BI＇I. It predigests the test process and improves the test precision by taking the rectangular pulse as stimulator and analog switch as auxiliary bridge. The experiment of uA741 shows that the design is feasible. Compared with the traditional test method, it is better regarding reliability and measurability of the analog circuit system.展开更多
A static approach method method is used to get the spectrum expression of the pulse interval modulation signal.The expression is simple,has a clear physical concept and it has been confirmed by a simultaneous experiment.
The Directions of Arrivals （DOAs）, speeds and distances of targets are all required for array signal processing. Based on the periodic phase shift of coherent pulse sequence waveform, a new estimation of multi-targ...The Directions of Arrivals （DOAs）, speeds and distances of targets are all required for array signal processing. Based on the periodic phase shift of coherent pulse sequence waveform, a new estimation of multi-targets＇ 2-Dimentional （2-D） DOA angle, Doppler frequency shift and relative time-delay is proposed. Based on a virtual sensor array constructed by pulse cumulating, the estinaations of azimuth, elevation, Doppler frequency shift and time-delay can be obtained simultaneously, and the least number of pulses could be two. This method is computationally efficient even in heavier noised environment, and all estimations are automatically paired in calculation process with no used to any plane sensor array and deal with many spectrum searching. Further more, this algorithm can be targets at the same time only by few sensors. The targets number that can deal with simultaneously is several times to the sensor number, which is the upper limit for normal algorithms such as ESPRIT and MUSIC. These characteristics would be very useful, especially, for aerial systems. Simulations demonstrate the capabilities of this method efficiently.展开更多
Focused underwater plasma sound sources are being applied in more and more fields. Focusing performance is one of the most important factors determining transmission distance and peak values of the pulsed sound waves....Focused underwater plasma sound sources are being applied in more and more fields. Focusing performance is one of the most important factors determining transmission distance and peak values of the pulsed sound waves. The sound source’s components and focusing mechanism were all analyzed. A model was built in 3D Max and wave strength was measured on the simulation platform. Error analysis was fully integrated into the model so that effects on sound focusing performance of processing-errors and installation-errors could be studied. Based on what was practical, ways to limit the errors were proposed. The results of the error analysis should guide the design, machining, placement, debugging and application of underwater plasma sound sources.展开更多
Given is an analysis of broad-band Er-doped superfluorescent fiber source(EDSFS)filter using long period chirped fiber grating by transmission matrix method.For our EDSFS attenuated amplitude demand and the flattened ...Given is an analysis of broad-band Er-doped superfluorescent fiber source(EDSFS)filter using long period chirped fiber grating by transmission matrix method.For our EDSFS attenuated amplitude demand and the flattened wavelength range demand,proposed are the key factors of designing such filters of high performances.The simulation result demonstrates that such type filters have an enough attenuation to flatten the dramatic increase in output amplified spontaneous emission(ASE)in the wavelength range of 1529nm^1535nm by choosing conformable fiber filter parameters such as chirped degree,original period,induced index change,length of the fiber filter,and then broad-band EDSFS could be achieved.展开更多
The simulation of the early-time High-altitude Electromagnetic Pulse （HEMP） environment （El） with bicone-cage antenna in free space requires utilization of the spherical wave to reproduce the boundless plane wave....The simulation of the early-time High-altitude Electromagnetic Pulse （HEMP） environment （El） with bicone-cage antenna in free space requires utilization of the spherical wave to reproduce the boundless plane wave. The transient radiation of the antenna above the lossy ground is computed using the Finite-Difference Time-Domain （FDTD） method The determining factors of the field waveform are explored and analysed on the basis of the physical evolution process of the transient radiation. The typical waveform of the electric field and the field distribution characteristics, both of which are important for HEMP simulator design and the effect tests, are presented. The study indicates that the simulation should be analysed from the perspective of both environment building and simulator applications.展开更多
The laser bending of single-crystal silicon sheet （0.2 mm in thickness） was investigated with JK701 Nd：YAG laser. The models were developed to describe the beam characteristics of pulsed laser. In order to simulate...The laser bending of single-crystal silicon sheet （0.2 mm in thickness） was investigated with JK701 Nd：YAG laser. The models were developed to describe the beam characteristics of pulsed laser. In order to simulate the process of laser bending, the FEM software ANSYS was used to predict the heat temperature and stress-strain fields. The periodic transformation of temperature field and stress-strain distribution was analyzed during pulsed laser scanning silicon sheet. The results indicate that the mechanism of pulsed laser bending silicon is a hybrid mechanism in silicon bending, rather than a simple mechanism of TGM or BM. This work also gets silicon sheet bent after scanning 6 times with pulsed laser, and its bending angle is up to 6.5°. The simulation and prediction results reach well agreement with the verifying experiments.展开更多
基金Supported by the National Natural Science Foundation of China(No.59976023)
文摘In the commercial utilization of rigid ceramic filters, the performance of pulse cleaning has crucial effects on the long-term stable operation. In order to get a clear insight into the nature of this cleaning process and provide a solid basis for industrial applications, the flow in ceramic candle filter was investigated. The flow in the pulse-jetspace and inside the ceramic candle is regarded as two- dimensional, unsteady, compressible flow, and numerical simulation is carried out by computational fluid dynamics. The numerical predictions of flow field are in good agreement with the experimental measurements. Effects of the candle diameter, the separation distance between the nozzle and the candle injector and the length of the candle on the flowfield have been numerically analyzed to provide the basis for the optimum design of the pulse cleaning system.
文摘This paper presents an analog circuit built-in-test （BIT） structure based on boundary scan and realizes the BI＇I. It predigests the test process and improves the test precision by taking the rectangular pulse as stimulator and analog switch as auxiliary bridge. The experiment of uA741 shows that the design is feasible. Compared with the traditional test method, it is better regarding reliability and measurability of the analog circuit system.
文摘A static approach method method is used to get the spectrum expression of the pulse interval modulation signal.The expression is simple,has a clear physical concept and it has been confirmed by a simultaneous experiment.
基金Supported by the NWPU Graduate Innovation Lab Cen-ter of China (No.04029)
文摘The Directions of Arrivals （DOAs）, speeds and distances of targets are all required for array signal processing. Based on the periodic phase shift of coherent pulse sequence waveform, a new estimation of multi-targets＇ 2-Dimentional （2-D） DOA angle, Doppler frequency shift and relative time-delay is proposed. Based on a virtual sensor array constructed by pulse cumulating, the estinaations of azimuth, elevation, Doppler frequency shift and time-delay can be obtained simultaneously, and the least number of pulses could be two. This method is computationally efficient even in heavier noised environment, and all estimations are automatically paired in calculation process with no used to any plane sensor array and deal with many spectrum searching. Further more, this algorithm can be targets at the same time only by few sensors. The targets number that can deal with simultaneously is several times to the sensor number, which is the upper limit for normal algorithms such as ESPRIT and MUSIC. These characteristics would be very useful, especially, for aerial systems. Simulations demonstrate the capabilities of this method efficiently.
基金Supported by the National Natural Science Foundation under Grant No.60572098
文摘Focused underwater plasma sound sources are being applied in more and more fields. Focusing performance is one of the most important factors determining transmission distance and peak values of the pulsed sound waves. The sound source’s components and focusing mechanism were all analyzed. A model was built in 3D Max and wave strength was measured on the simulation platform. Error analysis was fully integrated into the model so that effects on sound focusing performance of processing-errors and installation-errors could be studied. Based on what was practical, ways to limit the errors were proposed. The results of the error analysis should guide the design, machining, placement, debugging and application of underwater plasma sound sources.
文摘Given is an analysis of broad-band Er-doped superfluorescent fiber source(EDSFS)filter using long period chirped fiber grating by transmission matrix method.For our EDSFS attenuated amplitude demand and the flattened wavelength range demand,proposed are the key factors of designing such filters of high performances.The simulation result demonstrates that such type filters have an enough attenuation to flatten the dramatic increase in output amplified spontaneous emission(ASE)in the wavelength range of 1529nm^1535nm by choosing conformable fiber filter parameters such as chirped degree,original period,induced index change,length of the fiber filter,and then broad-band EDSFS could be achieved.
文摘The simulation of the early-time High-altitude Electromagnetic Pulse （HEMP） environment （El） with bicone-cage antenna in free space requires utilization of the spherical wave to reproduce the boundless plane wave. The transient radiation of the antenna above the lossy ground is computed using the Finite-Difference Time-Domain （FDTD） method The determining factors of the field waveform are explored and analysed on the basis of the physical evolution process of the transient radiation. The typical waveform of the electric field and the field distribution characteristics, both of which are important for HEMP simulator design and the effect tests, are presented. The study indicates that the simulation should be analysed from the perspective of both environment building and simulator applications.
基金Projects (50975041, 50775019) supported by the National Natural Science Foundation of ChinaProjects (20062181, 2008S054) supported by Liaoning Province’s Government Science Fund, China
文摘The laser bending of single-crystal silicon sheet （0.2 mm in thickness） was investigated with JK701 Nd：YAG laser. The models were developed to describe the beam characteristics of pulsed laser. In order to simulate the process of laser bending, the FEM software ANSYS was used to predict the heat temperature and stress-strain fields. The periodic transformation of temperature field and stress-strain distribution was analyzed during pulsed laser scanning silicon sheet. The results indicate that the mechanism of pulsed laser bending silicon is a hybrid mechanism in silicon bending, rather than a simple mechanism of TGM or BM. This work also gets silicon sheet bent after scanning 6 times with pulsed laser, and its bending angle is up to 6.5°. The simulation and prediction results reach well agreement with the verifying experiments.
