The application of digital photogrammetry to measure distribution of tree positions with stereo image couple is introduced in detail, and the procedure of stereo vision applied in forestry environment is explored. Non...The application of digital photogrammetry to measure distribution of tree positions with stereo image couple is introduced in detail, and the procedure of stereo vision applied in forestry environment is explored. Nonlinear error in measure model is adopted in the camera calibration; the interactive correlation matching is used under constraint of epipolar line and edge of tree detected by Canny operator. Results prove that application of digital photogrammetry technology to measure distribution of tree positions can meet demand of precision in experimental conditions.展开更多
With the onset of winter, polar marine microalgae would have faced total darkness for aperiod of up to 6 months. A natural autumn community of Arctic sea ice microalgae was collected for dark survival experiments from...With the onset of winter, polar marine microalgae would have faced total darkness for aperiod of up to 6 months. A natural autumn community of Arctic sea ice microalgae was collected for dark survival experiments from the Greenland Sea during the ARKTIS-XI/2 Expedition of RV Po-larstem in October 1995. After a dark period of 161 days, species dominance in the algal assemblage have changed from initially pennate diatoms to small phytoflagellates (<20 μm). Over the entire dark period, the mean algal growth rate was - 0.01 d-1. Nearly all diatom species had negative growth rates, while phytoflagellate abundance increased. Resting spore formation during the dark period was observed in less than 4.5% of all cells and only for dinoflagellates and the diatom Chaetoceros spp. We assume that facultative heterotrophy and energy storage are the main processes enabling survival during the dark Arctic winter. After an increase in light intensity, microalgal cells reacted with fast growth within days. Phytoflagellates had the highest growth rate, followed by Nitzschia frigida. Further investigations and experiments should focus on the mechanisms of dark survival (mixotrophy and energy storage) of polar marine microalgae.展开更多
Innovation is the first driving force to lead the development. The development of the country cannot be separated from innovation. High school is a key period for students to learn, and the cultivation of their creati...Innovation is the first driving force to lead the development. The development of the country cannot be separated from innovation. High school is a key period for students to learn, and the cultivation of their creative thinking can benefit their whole lives. High school mathematics presents the characteristics of theorization, abstraction and strong logicality, which makes it difficult for students to learn. However, the traditional teaching concept pays attention to the inculcation of knowledge, which is not conducive to the students to truly form good mathematics learning habits. To do a good job in senior high school mathematics education, we should start from the perspective of cultivating students creative thinking ability, and comprehensively improve students ability to solve mathematical problems by creating diversified teaching situations, changing teaching concepts, strengthening classroom interaction, cultivating students associative creativity and other methods.展开更多
基金the National Natural Science Foundationof China (Grant No. 30271079)
文摘The application of digital photogrammetry to measure distribution of tree positions with stereo image couple is introduced in detail, and the procedure of stereo vision applied in forestry environment is explored. Nonlinear error in measure model is adopted in the camera calibration; the interactive correlation matching is used under constraint of epipolar line and edge of tree detected by Canny operator. Results prove that application of digital photogrammetry technology to measure distribution of tree positions can meet demand of precision in experimental conditions.
基金This project was supported by the National Natural Science Foundation of China under contract No. 49906006.
文摘With the onset of winter, polar marine microalgae would have faced total darkness for aperiod of up to 6 months. A natural autumn community of Arctic sea ice microalgae was collected for dark survival experiments from the Greenland Sea during the ARKTIS-XI/2 Expedition of RV Po-larstem in October 1995. After a dark period of 161 days, species dominance in the algal assemblage have changed from initially pennate diatoms to small phytoflagellates (<20 μm). Over the entire dark period, the mean algal growth rate was - 0.01 d-1. Nearly all diatom species had negative growth rates, while phytoflagellate abundance increased. Resting spore formation during the dark period was observed in less than 4.5% of all cells and only for dinoflagellates and the diatom Chaetoceros spp. We assume that facultative heterotrophy and energy storage are the main processes enabling survival during the dark Arctic winter. After an increase in light intensity, microalgal cells reacted with fast growth within days. Phytoflagellates had the highest growth rate, followed by Nitzschia frigida. Further investigations and experiments should focus on the mechanisms of dark survival (mixotrophy and energy storage) of polar marine microalgae.
文摘Innovation is the first driving force to lead the development. The development of the country cannot be separated from innovation. High school is a key period for students to learn, and the cultivation of their creative thinking can benefit their whole lives. High school mathematics presents the characteristics of theorization, abstraction and strong logicality, which makes it difficult for students to learn. However, the traditional teaching concept pays attention to the inculcation of knowledge, which is not conducive to the students to truly form good mathematics learning habits. To do a good job in senior high school mathematics education, we should start from the perspective of cultivating students creative thinking ability, and comprehensively improve students ability to solve mathematical problems by creating diversified teaching situations, changing teaching concepts, strengthening classroom interaction, cultivating students associative creativity and other methods.
