Spatiotemporal variations and its driving factors of soil conservation services in the Three Gorges Reservoir area in China

Soil conservation services play a vital role in regulating ecosystem services to prevent soil erosion and ensure regional ecological security. Therefore, effective evaluation and quantification of soil conservation services in the Three Gorges Reservoir Area (TGRA) are conducive to sustainable management under future global change. In this study, based on a basic database, including land use/cover data, soil data, topographic data, meteorological data, and NDVI (Normalized Difference Vegetation Index) data as the basic databases, to evaluate the temporal and spatial changes of soil conservation services in the TGRA from 1990 to 2015 at a regional-scale level using the general soil loss equation. The results showed that forest ecosystems (including coniferous and broad-leaved mixed forests, coniferous forests, shrub forests, and broad-leaved forests) made a greater contribution (69%) to regulating soil conservation in TGRA, followed by farmland ecosystems (29%). In total TGRA, large spatial variation in soil conservation, such as the highest appeared in the northern hinterland, whereas the lowest was mostly shown in the northwest with relatively frequent human activities and developed industry and agriculture. In general, soil conservation in the TGRA ecosystem gradually increased from 1990 to 2015, with a total increase of 6%. In this period, with the effective implementation of ecological projects, such as the conversion of farmland to forest and natural forest protection, the distributed proportion of forest land area in total TGRA showed a significant increase. In the meantime, the increase of vegetation coverage also helps the restoration of ecosystem structure and function and the improvement of soil conservation services. Our findings will aid our knowledge regarding the ecosystem services of the TGRA and provide implications for future sustainable land management and ecological protection

An Automatic Chinese Font Library Generation Method by Modifying Vector Contour Curves

Recently, the information leaking problem of important a per-based documents has become more and more serious, which is caused by scanning, copying and photographing methods. To deal with it, great development has been made in the text watermarking algorithms based on special font library. However, all the current font libraries are created manually with professional softwares with very low efficiency. Based on this consideration, in this paper, we propose an automatic watermarked font library generation method by modifying vector contour curves of Chinese characters. Firstly, the original vector contour curves data of character glyph is obtained and the skeleton curves are extracted after thinner processing. Then all the key points located on the skeleton curves are searched and filtered by the special rules. In the end, the vector contour curves around the selected key points are modified automatically and saved into a new font library. Experimental results show that the visual effect of the automatically generated watermarked font library by the proposed method is more perfect, which meets the needs of current text watermarking algorithms better. Meanwhile, it dramatically improves the production efficiency of watermarked font library generation with higher application value. ? 2014 IEEE.EICPCI-S(ISTP)

Bilinear Coons Patch and its Application in Security Pattern Design

Nowadays, with the rapid development of printing and publishing industry, security printing technology becomes more and more important. Meanwhile, security pattern design is one of the most important techniques of security printing. A well designed security pattern should be difficult to counterfeit in any way. Therefore it can be used in printed security documents, such as banknotes, passports and certificates, etc. In this paper, based on the generalization of Coons patch construction, we propose a novel scheme of security pattern design. The practical pattern examples are presented, and some other applications of the novel method are also discussed. ? 2009 IEEE.EI

A Moiré Removal Method Based on Peak Filtering and Image Enhancement

Screen photos often suffer from moiré patterns, which significantly affect their visual quality. Although many deep learning-based methods for removing moiré patterns have been proposed, they fail to recover images with complex textures and heavy moiré patterns. Here, we focus on text images with heavy moiré patterns and propose a new demoiré approach, incorporating frequency-domain peak filtering and spatial-domain visual quality enhancement. We find that the content of the text image mainly lies in the central region, whereas the moiré pattern lies in the peak region, in the frequency domain. Based on this observation, a peak-filtering algorithm and a central region recovery strategy are proposed to accurately locate and remove moiré patterns while preserving the text parts. In addition, to further remove the noisy background and paint the missing text parts, an image enhancement algorithm utilising the Otsu method is developed. Extensive experimental results show that the proposed method significantly removes severe moiré patterns from images with better visual quality and lower time cost compared to the state-of-the-art methods

An Adaptive Visible Watermark Embedding Method based on Region Selection

Aiming at the problem that the robustness, visibility, and transparency of the existing visible watermarking technologies are difficult to achieve a balance, this paper proposes an adaptive embedding method for visible watermarking. Firstly, the salient region of the host image is detected based on superpixel detection. Secondly, the flat region with relatively low complexity is selected as the embedding region in the nonsalient region of the host image. Then, the watermarking strength is adaptively calculated by considering the gray distribution and image texture complexity of the embedding region. Finally, the visible watermark image is adaptively embedded into the host image with slight adjustment by just noticeable difference (JND) coefficient. The experimental results show that our proposed method improves the robustness of visible watermarking technology and greatly reduces the risk of malicious removal of visible watermark image. Meanwhile, a good balance between the visibility and transparency of the visible watermark image is achieved, which has the advantages of high security and ideal visual effect

Spatio-Temporal Change of Multiple Ecosystem Services and Their Driving Factors: A Case Study in Beijing, China

Driven by rapid urbanization, land use patterns have undergone dramatic changes, which have in turn influenced ecosystem services (ESs). The government has implemented ecological compensation and conservation actions to mitigate this negative impact, especially in metropolises. However, whether these measures will have the desired effect remains unclear. Therefore, understanding the spatio-temporal characteristics of ESs and their driving factors are crucial for regional development. In this study, we quantified carbon storage, water yield and soil conservation services based on land use maps. A Geographical Detector (GD) was used to analyze the driving mechanisms of ES changes in Beijing from 1985 to 2020. The results showed that (1) the obvious landscape pattern changes are urbanization, afforestation and cultivated land degradation in Beijing, (2) the three services showed an increasing trend overall, but the changes were different in each period, (3) in general, land use change is the main factor affecting ESs, and the urbanization and afforestation contributed the most. These results suggest that in highly urbanized metropolises, humans can still balance the demands of regional development and ESs reasonable planning. This study highlights the importance of afforestation for ESs, the necessity of harmonizing environmental concerns and human activities, and the need to conduct ecological management in Beijing to protect the ecological environment and coordinate regional development

Urbanization Intensifies the Mismatch between the Supply and Demand of Regional Ecosystem Services: A Large-Scale Case of the Yangtze River Economic Belt in China

The process of rapid urbanization has been causing non-negligible disturbances to our ecosystems, which has aggravated the mismatch between ecosystem service (ES) supply and demand. A clear understanding of the relationship between the ES supply–demand mismatch and urbanization is crucial as it could have a lot of significance for implementing ecological compensation and conservation action. Although a large number of studies have explored this problem, previous studies have focused primarily on the spatial mismatching of the ESs, and only a few studies have considered the spatial relationship between the ES supply–demand mismatch and urbanization at the watershed scale. Taking the Yangtze River Economic Belt (YREB) as an example, this study quantitatively assesses the supply and demand of five ESs, including carbon sequestration, water retention, soil conservation, food production, and recreational opportunity. The bivariate Moran’s I method was used to analyze and visualize the spatial correlation between the ES supply–demand mismatch and urbanization. The results indicate that both the total supply and the total demand of the five ESs increased, while the increasing rate of total demand was higher than the total supply of the ESs; this resulted in a significant spatial mismatch between the supply and demand of the ESs from 2000 to 2020. There is also a negative spatial correlation between the ES supply–demand and urbanization, while the results of local spatial clustering have obvious spatial heterogeneity. The metropolis and its surrounding counties are mostly the ES supply and demand deficit area, but some surrounding counties have managed to transform a deficit into a surplus. These results indicate that urbanization has a certain interference on the mismatch of the ES supply and demand, and this interference is not irreversible. Moreover, this study provides a reliable reference for government management in the context of balancing urbanization and the ecosystem

Sparse-TFM Imaging of Lamb Waves for the Near-Distance Defects in Plate-Like Structures

The ultrasonic phased array total focusing method (TFM) has the advantages of high imaging resolution and high sensitivity to small defects. However, it has a long imaging time and cannot realize near-distance defect imaging, which limits its application for industrial detection. A sparse-TFM algorithm is adopted in this work to solve the problem regarding rapid imaging of near- distance defects in thin plates. Green’s function is reconstructed through the cross-correlation of the diffuse full matrix captured by the ultrasonic phased array. The reconstructed full matrix recovers near-distance scattering information submerged by noise. A sparse array is applied to TFM for rapid imaging. In order to improve the imaging resolution, the location of active array elements in the sparse array can be optimized using the genetic algorithm (GA). Experiments are conducted on three aluminium plates with near-distance defects. The experimental results confirm that the sparse-TFM algorithm of Lamb waves can be used for near-distance defects imaging, which increases the computational efficiency by keeping the imaging accuracy. This paper provides a theoretical guidance for Lamb wave non-destructive testing of the near-distance defects in plate-like structures