<div style="text-align:justify;"> A scheme of frequency sweep linearization of semiconductor lasers using a feed-back loop based on amplitude-frequency response is demonstrated in this paper. The beat ...<div style="text-align:justify;"> A scheme of frequency sweep linearization of semiconductor lasers using a feed-back loop based on amplitude-frequency response is demonstrated in this paper. The beat frequency signal is obtained by self-heterodyne detection. The frequency changes are converted to the envelope of beat frequency signal after amplitude-frequency response. The active frequency sweep linearization is realized by feeding envelope deviations back to the drive currents of the lasers by a feedback loop. A simulation model is built to verify this scheme by Simulink. This scheme does not need high-performance, expensive lasers, complex linearization or tedious post-processing processes, which are of great significance for related applications. </div>展开更多
<div style="text-align:justify;"> In this work, a design of a compact optical MEMS-based lidar scanning system with a large field of view (FOV) and small distortion is presented. The scanning system ap...<div style="text-align:justify;"> In this work, a design of a compact optical MEMS-based lidar scanning system with a large field of view (FOV) and small distortion is presented. The scanning system applies an off-axis structure and the length of the system can be reduced to about 10 cm in an optimized way. Simulation results show that a large FOV is achieved under a uniform scanning scheme. In addition, the spot size less than 20 cm at distance of 100 m is also realized. The optical scanning system can be used for the vehicle-mounted Lidar. </div>展开更多
<div style="text-align:justify;"> Aiming at the problems of LED-based visible light positioning system such as unstable illumination, Lambertian model transmission limitation, large positioning error, ...<div style="text-align:justify;"> Aiming at the problems of LED-based visible light positioning system such as unstable illumination, Lambertian model transmission limitation, large positioning error, etc., it is proposed to use PWM to drive the LED, use the curve fitting method to obtain the ranging model, and estimate the target position according to the trilateral algorithm. A positioning system platform based on the microcontroller MiniSTM32 was built to test the performance of the transceiver circuit. The experimental results showed that the positioning error of less than 3 cm was achieved in a space of 80 cm × 80 cm × 80 cm. </div>展开更多
In industrial process control systems,there is overwhelming evidence corroborating the notion that economic or technical limitations result in some key variables that are very difficult to measure online.The data-driv...In industrial process control systems,there is overwhelming evidence corroborating the notion that economic or technical limitations result in some key variables that are very difficult to measure online.The data-driven soft sensor is an effective solution because it provides a reliable and stable online estimation of such variables.This paper employs a deep neural network with multiscale feature extraction layers to build soft sensors,which are applied to the benchmarked Tennessee-Eastman process(TEP)and a real wind farm case.The comparison of modelling results demonstrates that the multiscale feature extraction layers have the following advantages over other methods.First,the multiscale feature extraction layers significantly reduce the number of parameters compared to the other deep neural networks.Second,the multiscale feature extraction layers can powerfully extract dataset characteristics.Finally,the multiscale feature extraction layers with fully considered historical measurements can contain richer useful information and improved representation compared to traditional data-driven models.展开更多
Photocatalytic optical fibers are promising for the degradation of gaseous and volatile pollutants in air due to their high specific surface area,high light utilization efficiency,easy regeneration,and sustainability....Photocatalytic optical fibers are promising for the degradation of gaseous and volatile pollutants in air due to their high specific surface area,high light utilization efficiency,easy regeneration,and sustainability.In particular,photocatalytic optical fibers have proven highly useful for the removal and conversion of different kinds of air pollutants in air.However,these fibers suffer from low photocatalytic degradation efficiencies.In this review,we have focused on introducing photocatalytic quartz optical fibers and photocatalytic plastic optical fibers for the degradation and transformation of gas-phase air pollutants.The principle of photocatalytic optical fibers and main methods for improving their photocatalytic and light utilization efficiencies based on semiconductor photocatalytic coatings are summarized.Moreover,the Langmuir-Hinshelwood kinetic rate equation was summarized to analyze the photocatalytic reduction of gaseous pollutants.Finally,an outlook on the future of photocatalytic optical fibers toward the removal and conversion of gaseous air pollutants is discussed.展开更多
文摘<div style="text-align:justify;"> A scheme of frequency sweep linearization of semiconductor lasers using a feed-back loop based on amplitude-frequency response is demonstrated in this paper. The beat frequency signal is obtained by self-heterodyne detection. The frequency changes are converted to the envelope of beat frequency signal after amplitude-frequency response. The active frequency sweep linearization is realized by feeding envelope deviations back to the drive currents of the lasers by a feedback loop. A simulation model is built to verify this scheme by Simulink. This scheme does not need high-performance, expensive lasers, complex linearization or tedious post-processing processes, which are of great significance for related applications. </div>
文摘<div style="text-align:justify;"> In this work, a design of a compact optical MEMS-based lidar scanning system with a large field of view (FOV) and small distortion is presented. The scanning system applies an off-axis structure and the length of the system can be reduced to about 10 cm in an optimized way. Simulation results show that a large FOV is achieved under a uniform scanning scheme. In addition, the spot size less than 20 cm at distance of 100 m is also realized. The optical scanning system can be used for the vehicle-mounted Lidar. </div>
文摘<div style="text-align:justify;"> Aiming at the problems of LED-based visible light positioning system such as unstable illumination, Lambertian model transmission limitation, large positioning error, etc., it is proposed to use PWM to drive the LED, use the curve fitting method to obtain the ranging model, and estimate the target position according to the trilateral algorithm. A positioning system platform based on the microcontroller MiniSTM32 was built to test the performance of the transceiver circuit. The experimental results showed that the positioning error of less than 3 cm was achieved in a space of 80 cm × 80 cm × 80 cm. </div>
基金supported by National Natural Science Foundation of China(No.61873142)the Science and Technology Research Program of the Chongqing Municipal Education Commission,China(Nos.KJZD-K202201901,KJQN202201109,KJQN202101904,KJQN202001903 and CXQT21035)+2 种基金the Scientific Research Foundation of Chongqing University of Technology,China(No.2019ZD76)the Scientific Research Foundation of Chongqing Institute of Engineering,China(No.2020xzky05)the Chongqing Municipal Natural Science Foundation,China(No.cstc2020jcyj-msxmX0666).
文摘In industrial process control systems,there is overwhelming evidence corroborating the notion that economic or technical limitations result in some key variables that are very difficult to measure online.The data-driven soft sensor is an effective solution because it provides a reliable and stable online estimation of such variables.This paper employs a deep neural network with multiscale feature extraction layers to build soft sensors,which are applied to the benchmarked Tennessee-Eastman process(TEP)and a real wind farm case.The comparison of modelling results demonstrates that the multiscale feature extraction layers have the following advantages over other methods.First,the multiscale feature extraction layers significantly reduce the number of parameters compared to the other deep neural networks.Second,the multiscale feature extraction layers can powerfully extract dataset characteristics.Finally,the multiscale feature extraction layers with fully considered historical measurements can contain richer useful information and improved representation compared to traditional data-driven models.
基金the National Natural Science Foundation of China(NSFC)(Nos.51876018and 52176178)the Innovation research group of universities in Chongqing(No.CXQT21035)+2 种基金the Postgraduate Research Innovation Project of Chongqing University of Technology(No.ycx20192047)the Postgraduate Research Innovation Project of Chongqing(Nos.CYS18309 and CYS19318)the Science and Technology Research Project of Chongqing Education Commission(No.KJQN201801126)。
文摘Photocatalytic optical fibers are promising for the degradation of gaseous and volatile pollutants in air due to their high specific surface area,high light utilization efficiency,easy regeneration,and sustainability.In particular,photocatalytic optical fibers have proven highly useful for the removal and conversion of different kinds of air pollutants in air.However,these fibers suffer from low photocatalytic degradation efficiencies.In this review,we have focused on introducing photocatalytic quartz optical fibers and photocatalytic plastic optical fibers for the degradation and transformation of gas-phase air pollutants.The principle of photocatalytic optical fibers and main methods for improving their photocatalytic and light utilization efficiencies based on semiconductor photocatalytic coatings are summarized.Moreover,the Langmuir-Hinshelwood kinetic rate equation was summarized to analyze the photocatalytic reduction of gaseous pollutants.Finally,an outlook on the future of photocatalytic optical fibers toward the removal and conversion of gaseous air pollutants is discussed.