Tree Species Classification of Forest Stands Using Multisource Remote Sensing Data

The spatial distribution of forest stands is one of the fundamental properties of forests. Timely and accurately obtained stand distribution can help people better understand, manage, and utilize forests. The development of remote sensing technology has made it possible to map the distribution of tree species in a timely and accurate manner. At present, a large amount of remote sensing data have been accumulated, including high-spatial-resolution images, time-series images, light detection and ranging (LiDAR) data, etc. However, these data have not been fully utilized. To accurately identify the tree species of forest stands, various and complementary data need to be synthesized for classification. A curve matching based method called the fusion of spectral image and point data (FSP) algorithm was developed to fuse high-spatial-resolution images, time-series images, and LiDAR data for forest stand classification. In this method, the multispectral Sentinel-2 image and high-spatial-resolution aerial images were first fused. Then, the fused images were segmented to derive forest stands, which are the basic unit for classification. To extract features from forest stands, the gray histogram of each band was extracted from the aerial images. The average reflectance in each stand was calculated and stacked for the time-series images. The profile curve of forest structure was generated from the LiDAR data. Finally, the features of forest stands were compared with training samples using curve matching methods to derive the tree species. The developed method was tested in a forest farm to classify 11 tree species. The average accuracy of the FSP method for ten performances was between 0.900 and 0.913, and the maximum accuracy was 0.945. The experiments demonstrate that the FSP method is more accurate and stable than traditional machine learning classification methods

Elaborate Monitoring of Land-Cover Changes in Cultural Landscapes at Heritage Sites Using Very High-Resolution Remote-Sensing Images

Insufficient data and imperfect methods are the main obstacles to realize Target 11.4 of the Sustainable Development Goals (SDGs). Very high-resolution (VHR) remote sensing provides a useful tool to elaborate monitor land-cover changes in cultural landscapes so as to evaluate the authenticity and integrity of the cultural heritage sites (CHS). In this study, we developed a semi-automatic two-level workflow to efficiently extract delicate land-cover changes from bi-temporal VHR images (with spatial resolution ≤ 1 m), where most current studies can only manually interpret changes at this scale. Based on the monitoring result, we proposed an indicator named interference degree that can quantify the changes in cultural landscapes of the CHS as a complementary indicator to achieve Target 11.4 for SDGs. Three representative types of CHS with different landscapes were studied in 2015 and 2020 based on the VHR Google Earth images, including cave temples, ancient architectural buildings, and ancient sites. The proposed workflow was demonstrated to be effective in extracting delicate changes efficiently with the accuracy around 85%. The interference degree well reflects the preservation status of these CHS and can be periodically observed in a long term as an evaluation indicator. This study shows the potential to produce the first-hand global-monitoring data of CHS to support Target 11.4, thus serving for the sustainable development of the world’s cultural heritage

Mechanism of Rake Frame Shear Drainage during Gravity Dewatering of Ultrafine Unclassified Tailings for Paste Preparation

To study the mechanism of reverse percolation and drainage of unclassified tailings, improve the disposal concentration of tailings and solve the bottleneck in the development of filling technology, this study performed semi-industrial flocculation and sedimentation tests using macroscopic continuous thickener tests and a self-developed continuous thickener test platform to observe the evolution pattern and formation mechanism of unclassified tailings flocs. Then, in situ sampling was performed on the compressed thickener zone of tailings at the bottom of the bed with the help of industrial CT scanning tests and 3D images. Avizo software was used to establish the seepage channels and construct an evolutionary model to analyze the effect of tailings dewatering and concentration on tailings concentration from a microscopic perspective. The study shows that the distribution of seepage channels is closely related to the height of the bed. As the bed height increases, the bed concentration increases; shear has a significant effect on the water flow inside the pore space. After shear, the water between the sample pores has been discharged. Therefore, the flow rate is relatively slow. Shear produces pressure and tension effects, breaking the static equilibrium between flocs and water forming seepage channels. Shear can effectively break the floc structure and release the water so that the mutual position between flocs and water constantly changes, The concentration of the tailings bed is increased

Elaborate Monitoring of Land-Cover Changes in Cultural Landscapes at Heritage Sites Using Very High-Resolution Remote-Sensing Images

Insufficient data and imperfect methods are the main obstacles to realize Target 11.4 of the Sustainable Development Goals (SDGs). Very high-resolution (VHR) remote sensing provides a useful tool to elaborate monitor land-cover changes in cultural landscapes so as to evaluate the authenticity and integrity of the cultural heritage sites (CHS). In this study, we developed a semi-automatic two-level workflow to efficiently extract delicate land-cover changes from bi-temporal VHR images (with spatial resolution ≤ 1 m), where most current studies can only manually interpret changes at this scale. Based on the monitoring result, we proposed an indicator named interference degree that can quantify the changes in cultural landscapes of the CHS as a complementary indicator to achieve Target 11.4 for SDGs. Three representative types of CHS with different landscapes were studied in 2015 and 2020 based on the VHR Google Earth images, including cave temples, ancient architectural buildings, and ancient sites. The proposed workflow was demonstrated to be effective in extracting delicate changes efficiently with the accuracy around 85%. The interference degree well reflects the preservation status of these CHS and can be periodically observed in a long term as an evaluation indicator. This study shows the potential to produce the first-hand global-monitoring data of CHS to support Target 11.4, thus serving for the sustainable development of the world’s cultural heritage

Mechanism of Rake Frame Shear Drainage during Gravity Dewatering of Ultrafine Unclassified Tailings for Paste Preparation

To study the mechanism of reverse percolation and drainage of unclassified tailings, improve the disposal concentration of tailings and solve the bottleneck in the development of filling technology, this study performed semi-industrial flocculation and sedimentation tests using macroscopic continuous thickener tests and a self-developed continuous thickener test platform to observe the evolution pattern and formation mechanism of unclassified tailings flocs. Then, in situ sampling was performed on the compressed thickener zone of tailings at the bottom of the bed with the help of industrial CT scanning tests and 3D images. Avizo software was used to establish the seepage channels and construct an evolutionary model to analyze the effect of tailings dewatering and concentration on tailings concentration from a microscopic perspective. The study shows that the distribution of seepage channels is closely related to the height of the bed. As the bed height increases, the bed concentration increases; shear has a significant effect on the water flow inside the pore space. After shear, the water between the sample pores has been discharged. Therefore, the flow rate is relatively slow. Shear produces pressure and tension effects, breaking the static equilibrium between flocs and water forming seepage channels. Shear can effectively break the floc structure and release the water so that the mutual position between flocs and water constantly changes, The concentration of the tailings bed is increased

Reversible Mechanical Regulation and Splicing Ability of Alginate-Based Gel Based on Photo-Responsiveness of Molecular-Level Conformation

In this study, benefiting from the sensitive molecular conformation transversion in azobenzene, a new strategy for fabricating alginate gels with the abilities of splicing and photo-responsive mechanical adjustment is reported. Firstly, a 4,4’-azobis(benzoylhydrazide) (Azo-hydrazide) linker was used to crosslink alginate physically via the electrostatic interaction between hydrazide groups and carboxyl groups. It was then shaped and transferred in situ to a chemically crosslinked gel via 450 nm light irradiation. Under the irradiation, the molecular conformation change of azobenzene in the linker was able to form covalent bonds at the crosslinking points of the gels. Furthermore, the reversible conformation transformation of azobenzene was able to induce the increase and decrease of the storage modulus under irradiation with 365 nm light and 450 nm light, respectively, while also providing gel-like mechanical properties, depending upon the irradiation time and given wavelength. Meanwhile, the results also indicated that active groups could contribute to the splicing ability of the gel and construct a hollow cavity structure. It is believed that this work could provide a versatile strategy for preparing photo-responsive gels with reversibly tunable mechanical properties

Bamboo weaving inspired design of a carbonaceous electrode with exceptionally high volumetric capacity

A highly densified electrode material is desirable to achieve large volumetric capacity. However, pores acting as ion transport channels are critical for high utilization of active material. Achieving a balance between high volume density and pore utilization remains a challenge particularly for hollow materials. Herein, capillary force is employed to convert hollow fibers to a bamboo-weaving-like flexible electrode (BWFE), in which the shrinkage of hollow space results in high compactness of the electrode. The volume of the electrode can be decreased by 96% without sacrificing the gravimetric capacity. Importantly, the conductivity of BWFE after thermal treatment can reach up to 50,500 S/m which exceeds that for most other carbon materials. Detailed mechanical analysis reveals that, due to the strong interaction between nanoribbons, Young's modulus of the electrode increases by 105 times. After SnO2 active materials is impregnated, the BWFE/SnO2 electrode exhibits an exceptionally ultrahigh volumetric capacity of 2000 mAh/cm3.Submitted/Accepted versionThis work was supported by the High-Quality Development Project of the Ministry of Industry and Information Technology of the People’s Republic of China (TC210H041), the Hundred Talents program, the National Natural Science Foundation of China (Grant No. 51872304), and the Ningbo S&T Innovation 2025 Major Special Program (2018B10024; 2019B10(17); 2020Z101)