Abstract:Large-scale volcanic ash cloud could not only cause great changes in the global climate and environmental system, but also form a threat to aviation safety. Satellite remote sensing can quickly and accurately acquire the space change information in a large range. So it can implement the identification and early-warning of appearance and diffusion of volcanic ash cloud. Firstly, the spectral characteristics of volcanic ash cloud and the types of common satellite images are described. Then, the identification methods of volcanic ash cloud are presented systematically in the aspects of ultraviolet absorption, pattern recognition, split-window temperature difference and improved split-window temperature difference algorithms. Finally, the current study of volcanic ash cloud based on satellite images in China is reviewed and its trend is summarized and discussed.

Abstract:Monitoring the resources, ocean and atmospheric environment on earth by space remote sensing can provide predictive information and security for human's living environment. Infrared remote sensing instruments are the main detection payloads for earth observation satellites. With the improvement of the performance of infrared detectors and system integration technology, the detection capability of space-based infrared remote sensing instruments is developing greatly. Various kinds of high-performance earth observation satellites launched all over the world over last five years are presented. The application status, function and characteristics of some important infrared remote sensing instruments are summarized. Their future development trends are analyzed.

Abstract:A pulsed laser ranging system has a wide range of applications in different fields and its ranging accuracy depends on its time measurement accuracy. Because of some shortcomings, it is difficult for a traditional time measurement method to implement pulsed time measurement with high accuracy and sensitivity. A time-to-digital converter chip TDC-GP2 is described in detail. The chip utilizes the delay of logic gates to implement high accuracy time measurement. When it is used with a coarse counter, its maximum measurement range is 4 ms. On the basis of range 1 of the TDC-GP2 chip, high accuracy time measurement with typical resolution of 50 ps RMS in a measurement range from 0 to 1.8 μs can be implemented. This study is in a leading level among all kinds of time measurement methods.

Abstract:The crystal quality of InAlSb/InSb film materials may directly affect the performance of the eventual detection devices. To improve the crystal quality of film materials not only can reduce the dark current of detection devices, but also can improve the detectivity and uniformity of them. The preliminary result of a Molecular Beam Epitaxy (MBE) method for aluminum-doped InSb materials is reported. The crystal quality of the InAlSb film grown by MBE is analyzed by using a variety of test and analysis methods. The factors which have influence on the crystal quality are found out and the technical level of the MBE of InAlSb film materials is improved. The experimental result shows that through optimization of the growth conditions such as growth temperature, beam ratio, cooling rate and annealing process, high quality MBE InAlSb film materials can be obtained.

Abstract:Classification of electro-optic signal environment is of great significance to the winning of an informationized war. By analyzing the elements and indicator system construction principle of electro-optic signal environment, an indicator system for electro-optic signal environment classification is established systematically. The classification judgment function is constructed by an index factor and is further modified according to the detector's ability against interference. The proposed model is based on theoretical analysis. Since the electro-optic signal environment and the anti-interference measures are considered and both qualitative and quantitative analysis principles are incorporated, calculation is carried out easily. Finally, the correctness of the model is verified in several examples.

Abstract:According to the channel characteristics of the data acquired by the Infrared Atmospheric Sounder (IRAS) onboard FY-3B meteorological satellite, the spectral characteristics of cloud in different channels are analyzed. Unlike the threshold method based on channel brightness temperature deviation, the channel multispectral information and the method based on smooth gradient and channel signal-to-noise ratio are used to study the cloud detection of the data from FY-3B/IRAS. The cloud field-of-view is identified effectively. The deviation of the IRAS data from 00 UTC, 9 Jan, 2013 to 00 UTC 14 Jan, 2013 is corrected. Then, the cloud detection is conducted for the IRAS data. The result shows that the channel brightness temperature deviation after cloud detection obeys Gaussian distribution and meets the subsequent variational assimilation requirements of channel brightness for FY-3B/IRAS.

Abstract:A novel model for stripe noise reduction was proposed by combining moment matching with variational method, based on analyzing the characteristics of stripe noises in moderate resolution imaging spectroradiometer (MODIS) data. Firstly, multi-line and wide-line stripes were denoised by the moment matching method. Secondly, the stripes left in the result image were located by the improved stripe detection algorithm. Finally, based on the variational destrping model, Split Bregman iteration was adopted to reduce the strip noises. Experimental results show that the proposed algorithm can remove stripes in MODIS data and preserve the details of the image effectively. Compared with the destriping models including histogram matching, moment matching, low-pass filter and unidirectional variational destriping, the proposed method obtained more ideal results.

Abstract:To solve the problem of excessive enhancement when a POSHE algorithm is used to enhance infrared images, a histogram transform method based on 'optimal gray-level distribution' fitting is put forward and is verified in a MATLAB simulation experiment. The result shows that the method can not only alleviate the problem of excessive enhancement and eliminate the block effect phenomenon due to processing by the POSHE algorithm, but also inhibit the 'cold reflection image' of a cooled infrared detector. The whole information of an infrared image can be retained and form good visual effectiveness while the contrast of the image is enhanced.

Abstract:Impact of yijinjing 'supporting pile' on infrared characteristics of back meridians of neck type cervical spondylosis patients is discussed. 30 patients with neck type cervical spondylosis are trained to do yijinjin 'supporting pile' exercises regularly. Three months later, the infrared thermal images of the backs of those patients are collected in 10 minutes before and after doing exercises. It is found that for those patients, the infrared radiation trajectories (IRRTM) of their Du meridians can be induced obviously after doing yijinjing `supporting pile' exercises and those of their bladder meridians are not obvious. There is a significant difference between the variation of average temperature at the Da-zhui acupuncture point and that in the neck area (P<0.01). The variation after exercises is greater than that before exercises. The average temperature of the Du meridian after exercises is greater than that before exercises. There is a statistic difference in temperature variation (P<0.05). The result shows that through doing of yijinjing `supporting pile' exercises, the infrared radiation trajectories of Du meridians on the backs of patients can be induced significantly, become more continuous and neat and cause the temperature in the areas of Da-zhui acupuncture point, Du meridian and neck to rise.