It is very important to accurately recognize and locate pulverized and block coal seen in a coal mine's infrared image monitoring system. Infrared monitor images of pulverized and block coal were sampled in the ro...It is very important to accurately recognize and locate pulverized and block coal seen in a coal mine's infrared image monitoring system. Infrared monitor images of pulverized and block coal were sampled in the roadway of a coal mine. Texture statistics from the grey level dependence matrix were selected as the criterion for classification. The distributions of the texture statistics were calculated and analysed. A normalizing function was added to the front end of the BP network with one hidden layer. An additional classification layer is joined behind the linear layer. The recognition of pulverized from block coal images was tested using the improved BP network. The results of the experiment show that texture variables from the grey level dependence matrix can act as recognizable features of the image. The innovative improved BP network can then recognize the pulverized and block coal images.展开更多
Three kinds of nanometer-scale metal films(Cr,Ni and Ti)with different thicknesses are fabricated.The complex refractive indices of the three metal films are quantitatively measured by using THz differential time-doma...Three kinds of nanometer-scale metal films(Cr,Ni and Ti)with different thicknesses are fabricated.The complex refractive indices of the three metal films are quantitatively measured by using THz differential time-domain spectroscopy(THz-DTDS).The orders of the complex refractive indices of the thin metal films are equal to those of the reported values.Our results validated that THz-DTDS can be used to study the features of the ultra-thin metal films.展开更多
A monitoring system is an important guarantee of safety in a production mine. However, not all monitoring substations pass the electrical fast transient/burst （EFT/B） immunity test and the explosion-proof test simul...A monitoring system is an important guarantee of safety in a production mine. However, not all monitoring substations pass the electrical fast transient/burst （EFT/B） immunity test and the explosion-proof test simultaneously. To enhance the immunity, the values of capacitance and inductance should be increased, which are actually limited by coal mine explosion-proof standards. Hence, for the first time, an active filter was applied in an electromagnetic interference （EMI） output filter. As a result, the interference within 30 MHz clearly weakened, but the frequency spectrum had a wide range. An EMI input filter and ferrite beads were adopted to restrain higher frequency interference. An output interference spectrogram of the substation was obtained with an analyzer. The results indicate that the improved complex filtering markedly help to control interference. With the support of improved complex filtering and other enhancing immunity means about I/O ports, the substation managed to pass both the EFT/B immunity test and the explosion-proof test synchronously. We conclude that improved complex filtering is of vital importance in enhancing the electromagnetic compatibilitv （EMC） of the coal mine monitoring system.展开更多
In order to eliminate false alarms,issued by gas sensors in coal mining,caused by Electromagnetic Interference(EMI),both computer simulation and field measurements were introduced to analyze the underground EMI distri...In order to eliminate false alarms,issued by gas sensors in coal mining,caused by Electromagnetic Interference(EMI),both computer simulation and field measurements were introduced to analyze the underground EMI distribution.A simplified model of a sensor with metal enclosure was established and the effects of shielding properties about the enclosure aperture were studied.Because the haulage motor is the moving EMI source,varying with time,the onsite flameproof measuring instruments cannot accomplish synchronous measurements of electromagnetic field vectors.To simplify the field measurements,two sensors,one with a lead and the other without a lead,were chosen to conduct the contrasting measurements.The EMI current caused by the perforation lead was comparatively strong and therefore nickel zinc ferrite beads were used to cut off the EMI propagation paths.The peak value of the interference current was reduced by 20%-70% with the beads.After switching on the sensor power,the sen-sors still occasionally gave false alarms when the switch of nearby large-scale electric equipment was operated.A complex EMI filter was used and the EMI attenuated markedly.The running results demonstrated that false alarms had been eliminated.We con-clude that the improved shielding and filtering are highly significant in enhancing the immunity of the gas sensor.展开更多
The spontaneous combustion is a smoldering process and characterized by a slow burning speed and a long duration. Therefore, it is a hazard to coal mines. Early detection of coal mine spontaneous combustion is quite d...The spontaneous combustion is a smoldering process and characterized by a slow burning speed and a long duration. Therefore, it is a hazard to coal mines. Early detection of coal mine spontaneous combustion is quite difficult because of the complexity of different coal mines. And the traditional threshold discriminance is not suitable for spontaneous combustion detection due to the uncertainty of coalmine combustion. Restrictions of the single detection method will also affect the detection precision in the early time of spontaneous combustion. Although multiple detection methods can be adopted as a complementarity to improve the accuracy of detection, the synthesized method will in- crease the complicacy of criterion, making it difficult to estimate the combustion. To solve this problem, a fuzzy inference system based on CRI （Compositional Rule of Inference） and fuzzy reasoning method FITA （First Infer Then Aggregate） are presented. And the neural network is also developed to realize the fuzzy inference system. Finally, the effectiveness of the inference system is demonstrated bv means of an experiment.展开更多
To resolve the conflicting requirements of measurement precision and real-time performance speed,an im-proved algorithm for pattern classification and recognition was developed. The angular distribution of diffracted ...To resolve the conflicting requirements of measurement precision and real-time performance speed,an im-proved algorithm for pattern classification and recognition was developed. The angular distribution of diffracted light varies with particle size. These patterns could be classified into groups with an innovative classification based upon ref-erence dust samples. After such classification patterns could be recognized easily and rapidly by minimizing the vari-ance between the reference pattern and dust sample eigenvectors. Simulation showed that the maximum recognition speed improves 20 fold. This enables the use of a single-chip,real-time inversion algorithm. An increased number of reference patterns reduced the errors in total and respiring coal dust measurements. Experiments in coal mine testify that the accuracy of sensor achieves 95%. Results indicate the improved algorithm enhances the precision and real-time ca-pability of the coal dust sensor effectively.展开更多
An n-TiO_(2)/n−Si isotype heterojunction is fabricated by depositing TiO_(2) thin films onto n−Si substrates.Obvious photovoltaic behaviors are observed in this isotype heterojunction.The open circuit voltage and shor...An n-TiO_(2)/n−Si isotype heterojunction is fabricated by depositing TiO_(2) thin films onto n−Si substrates.Obvious photovoltaic behaviors are observed in this isotype heterojunction.The open circuit voltage and short circuit current of the heterojunction can reach 123 mV and 20µA/cm^(2),respectively.The mechanism for the photovoltaic behaviors can be understood in terms of the band alignment of the heterojunction.The results reported may provide a feasible route to easily available and low-cost isotyped photovoltaic devices.展开更多
基金Project 20050290010 supported by the Doctoral Foundation of Chinese Education Ministry
文摘It is very important to accurately recognize and locate pulverized and block coal seen in a coal mine's infrared image monitoring system. Infrared monitor images of pulverized and block coal were sampled in the roadway of a coal mine. Texture statistics from the grey level dependence matrix were selected as the criterion for classification. The distributions of the texture statistics were calculated and analysed. A normalizing function was added to the front end of the BP network with one hidden layer. An additional classification layer is joined behind the linear layer. The recognition of pulverized from block coal images was tested using the improved BP network. The results of the experiment show that texture variables from the grey level dependence matrix can act as recognizable features of the image. The innovative improved BP network can then recognize the pulverized and block coal images.
基金by the National Natural Science Foundation of China(No 60907046)the Natural Science Foundation of Henan Province of China(No 2009A140008).
文摘Three kinds of nanometer-scale metal films(Cr,Ni and Ti)with different thicknesses are fabricated.The complex refractive indices of the three metal films are quantitatively measured by using THz differential time-domain spectroscopy(THz-DTDS).The orders of the complex refractive indices of the thin metal films are equal to those of the reported values.Our results validated that THz-DTDS can be used to study the features of the ultra-thin metal films.
基金Project 50674093 supported by the National Natural Science Foundation of China
文摘A monitoring system is an important guarantee of safety in a production mine. However, not all monitoring substations pass the electrical fast transient/burst （EFT/B） immunity test and the explosion-proof test simultaneously. To enhance the immunity, the values of capacitance and inductance should be increased, which are actually limited by coal mine explosion-proof standards. Hence, for the first time, an active filter was applied in an electromagnetic interference （EMI） output filter. As a result, the interference within 30 MHz clearly weakened, but the frequency spectrum had a wide range. An EMI input filter and ferrite beads were adopted to restrain higher frequency interference. An output interference spectrogram of the substation was obtained with an analyzer. The results indicate that the improved complex filtering markedly help to control interference. With the support of improved complex filtering and other enhancing immunity means about I/O ports, the substation managed to pass both the EFT/B immunity test and the explosion-proof test synchronously. We conclude that improved complex filtering is of vital importance in enhancing the electromagnetic compatibilitv （EMC） of the coal mine monitoring system.
基金Project 50674093 supported by the National Natural Science Foundation of China
文摘In order to eliminate false alarms,issued by gas sensors in coal mining,caused by Electromagnetic Interference(EMI),both computer simulation and field measurements were introduced to analyze the underground EMI distribution.A simplified model of a sensor with metal enclosure was established and the effects of shielding properties about the enclosure aperture were studied.Because the haulage motor is the moving EMI source,varying with time,the onsite flameproof measuring instruments cannot accomplish synchronous measurements of electromagnetic field vectors.To simplify the field measurements,two sensors,one with a lead and the other without a lead,were chosen to conduct the contrasting measurements.The EMI current caused by the perforation lead was comparatively strong and therefore nickel zinc ferrite beads were used to cut off the EMI propagation paths.The peak value of the interference current was reduced by 20%-70% with the beads.After switching on the sensor power,the sen-sors still occasionally gave false alarms when the switch of nearby large-scale electric equipment was operated.A complex EMI filter was used and the EMI attenuated markedly.The running results demonstrated that false alarms had been eliminated.We con-clude that the improved shielding and filtering are highly significant in enhancing the immunity of the gas sensor.
基金Project 20050290010 supported by the Doctoral Foundation of Chinese Education Ministry and 2005AA133070 by National 863 Program for High Technique Research Development
文摘The spontaneous combustion is a smoldering process and characterized by a slow burning speed and a long duration. Therefore, it is a hazard to coal mines. Early detection of coal mine spontaneous combustion is quite difficult because of the complexity of different coal mines. And the traditional threshold discriminance is not suitable for spontaneous combustion detection due to the uncertainty of coalmine combustion. Restrictions of the single detection method will also affect the detection precision in the early time of spontaneous combustion. Although multiple detection methods can be adopted as a complementarity to improve the accuracy of detection, the synthesized method will in- crease the complicacy of criterion, making it difficult to estimate the combustion. To solve this problem, a fuzzy inference system based on CRI （Compositional Rule of Inference） and fuzzy reasoning method FITA （First Infer Then Aggregate） are presented. And the neural network is also developed to realize the fuzzy inference system. Finally, the effectiveness of the inference system is demonstrated bv means of an experiment.
基金Project 50674093 supported by the National Natural Science Foundation of China
文摘To resolve the conflicting requirements of measurement precision and real-time performance speed,an im-proved algorithm for pattern classification and recognition was developed. The angular distribution of diffracted light varies with particle size. These patterns could be classified into groups with an innovative classification based upon ref-erence dust samples. After such classification patterns could be recognized easily and rapidly by minimizing the vari-ance between the reference pattern and dust sample eigenvectors. Simulation showed that the maximum recognition speed improves 20 fold. This enables the use of a single-chip,real-time inversion algorithm. An increased number of reference patterns reduced the errors in total and respiring coal dust measurements. Experiments in coal mine testify that the accuracy of sensor achieves 95%. Results indicate the improved algorithm enhances the precision and real-time ca-pability of the coal dust sensor effectively.
基金Supported by the National Natural Science Foundation of China under Grant No 60907046.
文摘An n-TiO_(2)/n−Si isotype heterojunction is fabricated by depositing TiO_(2) thin films onto n−Si substrates.Obvious photovoltaic behaviors are observed in this isotype heterojunction.The open circuit voltage and short circuit current of the heterojunction can reach 123 mV and 20µA/cm^(2),respectively.The mechanism for the photovoltaic behaviors can be understood in terms of the band alignment of the heterojunction.The results reported may provide a feasible route to easily available and low-cost isotyped photovoltaic devices.
