21 results on '"Chen, Weifeng"'
Search Results
2. Effect of Straw Mulching and Deep Burial Mode on Water and Salt Transport Regularity in Saline Soils.
- Author
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Li, Mengzhu, Wang, Wei, Wang, Xiaofang, Yao, Chunmei, Wang, Yuanbo, Wang, Zanxia, Zhou, Weizhi, Chen, Endian, and Chen, Weifeng
- Subjects
SOIL salinity ,SALINE waters ,MULCHING ,STRAW ,SOIL management - Abstract
To examine the impacts of various straw mulching techniques, this study used the indoor soil column test as the primary research method and the field test as the validation test on the salinity dynamics of saline and alkaline soils. The experiment in this study was designed with five treatments: SC means for straw covered on the soil surface; DB means for straw buried 40 cm below the soil surface; S1D1, S2D1, and S1D2 represent the ratio of soil surface cover to the amount of straw buried 40 cm below the soil surface as 1:1, 2:1, and 1:2, respectively. The results of the indoor soil column test showed that all kinds of straw mulching techniques could effectively reduce soil moisture evaporation, and the straw mulching and deep burial mode was more effective: after 45 days of evaporation, compared with that of CK, the cumulative evaporation of soil moisture were reduced by 29.61%, 27.49%, 37.87%, 65.85%, and 54.58% for SC, DB, S1D1, S2D1, and S1D2, respectively; the straw mulching and deep burial mode could reduce the soil evaporation intensity more effectively than the single-layer straw mulching mode: the mean soil evaporation rates of CK, SC, DB, S1D1, S2D1 and S1D2 after 45 days of evaporation were 1.27 mm/day, 0.90 mm/day, 0.92 mm/day, 0.80 mm/day, 0.43 mm/day, and 0.58 mm/day; various straw mulching techniques could inhibit the accumulation of salts in the surface soil and effectively regulate the distribution of salts in the soil profile, among which the straw mulching and deep burial mode had the best effect of salinity suppression: after 30 days of evaporation, the re-salinization levels of the 0–40 cm soil layer of SC, DB, S1D1, S2D1, and S1D2 were reduced by 66.78%, 43.08%, 33.95%, 92.04% and 45.94% compared with that in the CK, respectively; there was a significant positive correlation between cumulative evaporation of soil moisture and cumulative soil salinity, which implied that cumulative soil salinity increased with the increase in cumulative evaporation of soil moisture. The results of the field experiment justified the results of the indoor soil column test: after four months of evaporation, the field moisture contents of CK, SC, DB, S1D1, S2D1, and S1D2 in the 0–20 cm soil layer were 14.77%, 3.51%, 15.10%, 15.26%, 18.73%, and 2.94%, respectively; during the experimental period, the salt inhibition rate of SC, DB, S1D1, S2D1 and S1D2 in 0–20 cm soil layer were 35.46%, 44.76%, 50.98%, 54.80% and 37.30%, respectively. Therefore, in a comprehensive view, S2D1 treatment had the best effect of salt and vapor suppression on saline soil. This study is of great significance for the resource utilization of straw waste, the improvement of water utilization and efficiency, and the management of soil salinization. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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3. Pyrolysis Atmospheres and Temperatures Co-Mediated Spectral Variations of Biochar-Derived Dissolved Organic Carbon: Quantitative Prediction and Self-Organizing Maps Analysis.
- Author
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Zhang, Huiying, Ni, Jinzhi, Qian, Wei, Yu, Shuhan, Xiang, Yu, Yang, Liuming, and Chen, Weifeng
- Subjects
SELF-organizing maps ,DISSOLVED organic matter ,COLLOIDAL carbon ,PYROLYSIS ,AIR flow ,ATMOSPHERE - Abstract
Biochar-derived dissolved organic carbon (BDOC), as a highly activated carbonaceous fraction of biochar, significantly affects the environmental effect of biochar. This study systematically investigated the differences in the properties of BDOC produced at 300–750 °C in three atmosphere types (including N
2 and CO2 flows and air limitation) as well as their quantitative relationship with biochar properties. The results showed that BDOC in biochar pyrolyzed in air limitation (0.19–2.88 mg/g) was more than that pyrolyzed in N2 (0.06–1.63 mg/g) and CO2 flows (0.07–1.74 mg/g) at 450–750 °C. The aliphaticity, humification, molecular weight, and polarity of BDOC strongly depended on the atmosphere types as well as the pyrolysis temperatures. BDOC produced in air limitation contained more humic-like substances (0.65–0.89) and less fulvic-like substances (0.11–0.35) than that produced in N2 and CO2 flows. The multiple linear regression of the exponential form of biochar properties (H and O contents, H/C and (O+N)/C) could be used to quantitatively predict the bulk content and organic component contents of BDOC. Additionally, self-organizing maps could effectively visualize the categories of fluorescence intensity and components of BDOC from different pyrolysis atmospheres and temperatures. This study highlights that pyrolysis atmosphere types are a crucial factor controlling the BDOC properties, and some characteristics of BDOC can be quantitatively evaluated based on the properties of biochar. [ABSTRACT FROM AUTHOR]- Published
- 2023
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4. Exploring City Image Perception in Social Media Big Data through Deep Learning: A Case Study of Zhongshan City.
- Author
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Su, Lei, Chen, Weifeng, Zhou, Yan, and Fan, Lei
- Abstract
Based on Kevin Lynch's cognitive method of urban image and Weibo's review data, this study constructs a research framework with three modules as the core: city image structure, city image types, and cultural service evaluation. First, the geospatial information carried by comments is analyzed by GIS to obtain the image structure of the city; second, the picture data in the comments are divided into image types and the type ratio is calculated by the image semantic segmentation method based on deep full convolution neural network. Finally, the text data in the comments are extracted from the semantic word frequency analysis to evaluate the cultural service perception index words of the city image and combined with the analysis of the city image structure and the city image type so as to obtain the integrated comprehensive perception of the city image. The research shows that the introduction of big data and deep learning methods into city image research can make up for the shortcomings of traditional research samples, expand the dimension and breadth of urban cognition, reveal the social, cultural, and functional characteristics of the city, and is an important supplement to the five-element model of city image depicting the material form of the city. In addition, the results of the empirical study, taking Zhongshan City as an example, have implications for the realistic urban spatial planning, urban landscape design, and tourism industry layout of Zhongshan. [ABSTRACT FROM AUTHOR]
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- 2023
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5. Ecosystem Service Value Evaluation of Saline—Alkali Land Development in the Yellow River Delta—The Example of the Huanghe Island.
- Author
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Liu, Jian, Chen, Xue, Chen, Weifeng, Zhang, Yong, Wang, Ailing, and Zheng, Yanfeng
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ALKALI lands ,VALUE (Economics) ,ECOSYSTEM services ,REAL estate development ,ECONOMIC indicators - Abstract
Saline–alkali land is an important land resource with high development potential and an important ecological product with high potential ecosystem service value (ESV). It is of great significance for rational development and protection of saline–alkali land resources to carry out research on the evaluation methods of the ESV of saline–alkali land and to scientifically quantify the ESV of saline–alkali land development. Taking typical saline–alkali land in the Yellow River Delta on the Huanghe Island of China as an example, this research constructed an ESV evaluation index system from the perspective of functional value containing three first-level indicators such as economic value, four second-level indicators such as supply service, and eight lowest-level indicators such as food production. It also considered production and operation costs and evaluated the ESV of the Huanghe Island using the ecological economics method. The results showed that the ESV of the Huanghe Island is CNY 133.586 million, and the unit area value is 50,200 CNY/hm
2 , which is a relatively high value. Among them, the supply service value was the highest, accounting for more than half. In recent years, the development of the Huanghe Island has produced high supply and service value, but due to weak background conditions and low vegetation coverage, regulation and support service values are relatively low, the cultural service value is still to be explored, and there is great potential for ecological and social value. This research can provide references for scientific evaluation of the ESV of saline–alkali land and provide a basis for rational development and utilization of the Huanghe Island. [ABSTRACT FROM AUTHOR]- Published
- 2023
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6. SLAM Overview: From Single Sensor to Heterogeneous Fusion.
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Chen, Weifeng, Zhou, Chengjun, Shang, Guangtao, Wang, Xiyang, Li, Zhenxiong, Xu, Chonghui, and Hu, Kai
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MULTISENSOR data fusion , *DETECTORS , *INDOOR positioning systems , *MOBILE robots , *DEEP learning , *HISTORY of technology - Abstract
After decades of development, LIDAR and visual SLAM technology has relatively matured and been widely used in the military and civil fields. SLAM technology enables the mobile robot to have the abilities of autonomous positioning and mapping, which allows the robot to move in indoor and outdoor scenes where GPS signals are scarce. However, SLAM technology relying only on a single sensor has its limitations. For example, LIDAR SLAM is not suitable for scenes with highly dynamic or sparse features, and visual SLAM has poor robustness in low-texture or dark scenes. However, through the fusion of the two technologies, they have great potential to learn from each other. Therefore, this paper predicts that SLAM technology combining LIDAR and visual sensors, as well as various other sensors, will be the mainstream direction in the future. This paper reviews the development history of SLAM technology, deeply analyzes the hardware information of LIDAR and cameras, and presents some classical open source algorithms and datasets. According to the algorithm adopted by the fusion sensor, the traditional multi-sensor fusion methods based on uncertainty, features, and novel deep learning are introduced in detail. The excellent performance of the multi-sensor fusion method in complex scenes is summarized, and the future development of multi-sensor fusion method is prospected. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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7. Neural Subspace Learning for Surface Defect Detection.
- Author
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Liu, Bin, Chen, Weifeng, Li, Bo, and Liu, Xiuping
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SURFACE defects , *MACHINE learning , *SUPERVISED learning , *LINEAR operators , *DEEP learning , *DATA augmentation - Abstract
Surface defect inspection is a key technique in industrial product assessments. Compared with other visual applications, industrial defect inspection suffers from a small sample problem and a lack of labeled data. Therefore, conventional deep-learning methods depending on huge supervised samples cannot be directly generalized to this task. To deal with the lack of labeled data, unsupervised subspace learning provides more clues for the task of defect inspection. However, conventional subspace learning methods focus on studying the linear subspace structure. In order to explore the nonlinear manifold structure, a novel neural subspace learning algorithm is proposed by substituting linear operators with nonlinear neural networks. The low-rank property of the latent space is approximated by limiting the dimensions of the encoded feature, and the sparse coding property is simulated by quantized autoencoding. To overcome the small sample problem, a novel data augmentation strategy called thin-plate-spline deformation is proposed. Compared with the rigid transformation methods used in previous literature, our strategy could generate more reliable training samples. Experiments on real-world datasets demonstrate that our method achieves state-of-the-art performance compared with unsupervised methods. More importantly, the proposed method is competitive and has a better generalization capability compared with supervised methods based on deep learning techniques. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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8. Fertilizer 15 N Fates of the Coastal Saline Soil-Wheat Systems with Different Salinization Degrees in the Yellow River Delta.
- Author
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Zhu, Kongming, Song, Fupeng, Duan, Fujian, Zhuge, Yuping, Chen, Weifeng, Yang, Quangang, Guo, Xinsong, Hong, Pizheng, Wan, Li, and Lin, Qun
- Subjects
SOIL salinity ,SOIL salinization ,FERTILIZERS ,SALINIZATION ,SOIL profiles ,SOIL erosion - Abstract
In order to clarify the fates of fertilizer N in coastal saline soil-wheat systems with different salinization degrees, this study was conducted to determine the
15 N uptake rates in various parts of wheat plant at maturity stage and the residual15 N in three different saline soils and the15 N loss of soil-wheat systems by using the15 N-labeled urea N tracing method in the Yellow River Delta. The results showed that: (1) The increase of soil salinity from 0.2% to 1% promoted the wheat plant to absorb N from soil and not from fertilizer and significantly inhibited the dry matter mass accumulation and15 N uptakes of each wheat parts and whole plant, but especially increased the total N concentration of wheat roots, stems, leaves, and grains. The aggravation of soil salinity significantly enhanced the distribution ratios of15 N uptakes and Ndffs in the wheat roots, stems, and leaves to depress the salt stress. (2) The15 N residues were mainly concentrated in the 0~20 cm saline soil layer and decreased as the soil profile deepened from 0 to 100 cm; the15 N residues decreased in the 0~40 cm soil profile layer and accumulated in the 40~100 cm with the increase of soil salinization degrees significantly. (3) The fates of15 N applied to the coastal saline soil-wheat system were wheat uptakes 1.53~13.96%, soil residues 10.05~48.69%, losses 37.35~88.42%, with the lowest15 N uptake and utilization in the three saline soils, the highest residual rate in lightly saline soils, and the highest loss in moderately and heavily saline soils. The increase of soil salinity inhibits wheat uptakes and soil residues and intensifies the losses from fertilizer15 N. Therefore, the fate of fertilizer N losses significantly increased as the degree of soil salinity increased. The conventional N management that was extremely inefficient for more N loss should be optimized to enhance the N efficiency and wheat yield of the coastal saline soil-wheat system in the Yellow River Delta. [ABSTRACT FROM AUTHOR]- Published
- 2022
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9. Regulation of Abiotic Factors on Aboveground Biomass and Biodiversity of Ditch Slope in Coastal Farmland.
- Author
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Wang, Yueying, Wang, Songtao, Jiang, Bing, Zhu, Yihao, Niu, Xuchang, Li, Changjiang, Wu, Zhen, and Chen, Weifeng
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SOIL salinity ,PLANT biomass ,DITCHES ,BIOMASS ,PLANT diversity ,BIODIVERSITY ,SOIL acidity - Abstract
Ditch plant biomass and diversity play an important role in maintaining ditch ecosystem structure and function stability, which are subject to environmental changes. However, the regulation of abiotic factors on the aboveground biomass and diversity of plants on the slopes of coastal agricultural ditches remains unclear. In this study, the spatial distribution of soil physicochemical properties, aboveground biomass, and diversity of vegetation on different slope positions (upper slope, middle slope, and lower slope) and slope aspects (north-south direction) of farmland drainage ditches and their correlations were investigated through field surveys of vegetation on the slopes of coastal farmland drainage ditches at different sampling sites. First, water content and bulk density) decreased with the increase of slope position, while the salinity showed the opposite spatial distribution characteristics and the distribution of soil nutrients in space was mainly concentrated in the 0–20 cm soil layer. Second, the aboveground biomass of vegetation was significantly higher on the south slope than on the north slope, with the highest biomass at the lower slope on the south slope and higher aboveground biomass on the north slope at the upper and middle slopes. The Shannon-Wiener index, Pielou index, and Margalef index of ditch slope vegetation in Dongying and Binzhou farmland ditch slopes showed the same pattern of change at different slope positions and directions, which were significantly higher at the upper and middle slopes than at the lower slopes. In contrast, the Simpson index showed the opposite pattern, decreasing with the increase in slope position. Further, WC, BD, organic matter content, and total nitrogen content had positive effects on vegetation aboveground biomass, while soil pH, salinity, and available potassium content hindered vegetation growth. Finally, the Shannon-Wiener index and Pielou index were positively correlated with soil BD and available phosphorus content, and negatively correlated with organic matter and total nitrogen content, while the Simpson index was positively correlated with soil BD and WC, and had a significant negative correlation with soil salinity. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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10. Spatio–Temporal Variability Characteristics of Coastal Soil Salinization and Its Driving Factors Detection.
- Author
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Song, Ying, Gao, Mingxiu, Wang, Zhuoran, Gong, Tengfei, and Chen, Weifeng
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SOIL salinity ,SOIL salinization ,SOIL moisture ,SPRING ,GEOGRAPHIC information systems ,SALINIZATION - Abstract
The utilization efficiency of land resources in the coastal area of the Yellow River Delta has been deeply affected by salinization hazards. Key to improvement of the utilization efficiency of resources in this area is to grasp the spatio–temporal variability law of soil salinity and identify the driving factors of salinization. Wudi County in the coastal area of the Yellow River Delta is taken as the study area. Based on the data obtained from field measurements and laboratory analysis, the characteristics of soil salinity in spring and summer were analyzed by classical statistical methods; the spatial differentiation characteristics of salinization were analyzed from two–dimensional and three–dimensional perspectives using the geographic information system (GIS) and groundwater modeling system (GMS); the time variation characteristics of salinization were quantitatively analyzed by introducing the salinization severity index (S
i ) and the dominant index of salinization degree change (Ci ). The results show that: (1) In the study area, the soil salinity of the surface layer (0–15 cm) in summer is lower than that in spring, but the sub–surface layer (15–30 cm), the middle layer (30–45 cm) and the bottom layer (45–60 cm) are all larger than the corresponding layers in spring, and the correlation between the soil salinity of each layer in summer is generally lower than that in spring. (2) In two–dimensional space, the areas with a surface soil salinity greater than 0.4% in both seasons are mainly located in the northern part of the study area; in three–dimensional space, the soil is mainly moderately salinized in both seasons, and the complexity of the distribution of the salt profile is higher in summer than in spring; (3) Mashanzi Town was the area most seriously affected by salinization in both seasons (Si values were greater than three); In the process of seasonal alternation, the dominant change type of salinized soil is from mild aggravation to moderate, with Ci value of 38.43%, followed by severe alleviation to moderate, with Ci value of 35.49%; (4) The driving factors of soil salinization in spring are mainly the soil salinity of the subsurface and middle layer, and soil water content; and in summer, mainly the soil salinity of subsurface layer, vegetation coverage and vegetation cover type. The interaction between any two factors has greater influence on the spatial variation of salinization than the corresponding single factor. [ABSTRACT FROM AUTHOR]- Published
- 2022
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11. An Overview on Visual SLAM: From Tradition to Semantic.
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Chen, Weifeng, Shang, Guangtao, Ji, Aihong, Zhou, Chengjun, Wang, Xiyang, Xu, Chonghui, Li, Zhenxiong, and Hu, Kai
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DEEP learning , *COMPUTER vision - Abstract
Visual SLAM (VSLAM) has been developing rapidly due to its advantages of low-cost sensors, the easy fusion of other sensors, and richer environmental information. Traditional visionbased SLAM research has made many achievements, but it may fail to achieve wished results in challenging environments. Deep learning has promoted the development of computer vision, and the combination of deep learning and SLAM has attracted more and more attention. Semantic information, as high-level environmental information, can enable robots to better understand the surrounding environment. This paper introduces the development of VSLAM technology from two aspects: traditional VSLAM and semantic VSLAM combined with deep learning. For traditional VSLAM, we summarize the advantages and disadvantages of indirect and direct methods in detail and give some classical VSLAM open-source algorithms. In addition, we focus on the development of semantic VSLAM based on deep learning. Starting with typical neural networks CNN and RNN, we summarize the improvement of neural networks for the VSLAM system in detail. Later, we focus on the help of target detection and semantic segmentation for VSLAM semantic information introduction. We believe that the development of the future intelligent era cannot be without the help of semantic technology. Introducing deep learning into the VSLAM system to provide semantic information can help robots better perceive the surrounding environment and provide people with higher-level help. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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12. Structure Determination, Mechanical Properties, Thermal Stability of Co 2 MoB 4 and Fe 2 MoB 4.
- Author
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Zhao, Shijing, Zhou, Wenju, Xiang, Xiaojun, Cao, Xuyan, Chen, Ning, Chen, Weifeng, Yu, Xiaohui, Yan, Bingmin, and Gou, Huiyang
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THERMAL stability ,CARBON dioxide ,DIFFERENTIAL thermal analysis ,LIGHT elements ,VICKERS hardness ,BORON ,TRANSITION metals - Abstract
The precise determination of atomic position of materials is critical for understanding the relationship between structure and properties, especially for compounds with light elements of boron and single or multiple transition metals. In this work, the single crystal X-ray diffraction is employed to analyze the atomic positions of Co
2 MoB4 and Fe2 MoB4 with a Ta3 B4 -type structure, and it is found that the lengths of B-B bonds connecting the two zig-zag boron chains are 1.86 Å and 1.87 Å, but previously unreported 1.4 Å. Co and Fe atoms occupy the same crystallographic position in lattice for the doped samples and the valence is close to the metal itself, and Co/Fe K-edge X-ray Absorption Fine Structure(XAFS) spectra of borides with different ratios of Co to Fe are collected to detect the local environment and chemical valence of Co and Fe. Vickers hardness and nano indentation measurements are performed, together with the Density Functional Theory (DFT) calculations. Finally, Co2 MoB4 possess better thermal stability than Fe2 MoB4 evaluated by Thermogravimetric Differential Thermal Analysis (TG-DTA) results. [ABSTRACT FROM AUTHOR]- Published
- 2022
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13. A Semi-Analytical Extraction Method for Interface and Bulk Density of States in Metal Oxide Thin-Film Transistors.
- Author
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Chen, Weifeng, Wu, Weijing, Zhou, Lei, Xu, Miao, Wang, Lei, Ning, Honglong, and Peng, Junbiao
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INTERFACES (Physical sciences) , *DENSITY of states , *METALLIC oxides , *THIN film transistors , *EXTRACTION (Chemistry) , *CURRENT-voltage characteristics - Abstract
A semi-analytical extraction method of interface and bulk density of states (DOS) is proposed by using the low-frequency capacitance--voltage characteristics and current--voltage characteristics of indium zinc oxide thin-film transistors (IZO TFTs). In this work, an exponential potential distribution along the depth direction of the active layer is assumed and confirmed by numerical solution of Poisson's equation followed by device simulation. The interface DOS is obtained as a superposition of constant deep states and exponential tail states. Moreover, it is shown that the bulk DOS may be represented by the superposition of exponential deep states and exponential tail states. The extracted values of bulk DOS and interface DOS are further verified by comparing the measured transfer and output characteristics of IZO TFTs with the simulation results by a 2D device simulator ATLAS (Silvaco). As a result, the proposed extraction method may be useful for diagnosing and characterising metal oxide TFTs since it is fast to extract interface and bulk density of states (DOS) simultaneously. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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14. Deterioration Process of Concrete Exposed to Internal Sulfate Attack.
- Author
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Chen, Weifeng, Huang, Bei, Yuan, Yuexue, and Deng, Min
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DETERIORATION of concrete , *GYPSUM , *SULFATES , *EXPANSION & contraction of concrete , *DIFFERENTIAL scanning calorimetry , *CRACKING of concrete , *ETTRINGITE , *SULFATE pulping process - Abstract
Damage to concrete structures with gypsum-contaminated aggregate occurs frequently. Aggregates in much of the southern part of China are contaminated with gypsum. Therefore, in this study, the effects of using different quantities of gypsum-contaminated aggregate on the expansion and compressive strength of concrete were investigated over a period of one year. Two groups of concrete were designed with the gypsum-contaminated aggregate containing different parts of fine and coarse aggregate, respectively. The SO3 contents were 0%, 0.5%, 1%, 1.5%, 3%, 5%, and 7% by weight of aggregate. X-ray diffraction (XRD), thermogravimetry (TG), and differential scanning calorimetry (DSC) were used to analyze the change in mineral composition over time. The microstructure was also studied by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The results showed that significant expansion and great loss in compressive strength did not occur in concrete if the content of SO3 lay below 1.5% and 3% in fine and coarse aggregates, respectively. The concentration of sulfate ions in concrete was not enough to form new a phase of gypsum. During the process of internal sulfate attack, the content of gypsum decreased and the content of ettringite increased. Ettringite was the main reason for the expansion damage of concrete. Additionally, the fracture mode of internal sulfate attack on concrete was the crack extension from gypsum to paste; finally, the aggregate separated from the paste. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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15. The Structure and Diversity of Nitrogen Functional Groups from Different Cropping Systems in Yellow River Delta.
- Author
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He, Huan, Miao, Yongjun, Zhang, Lvqing, Chen, Yu, Gan, Yandong, Liu, Na, Dong, Liangfeng, Dai, Jiulan, and Chen, Weifeng
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CROPPING systems ,WATERSHEDS ,DELTAS ,FUNCTIONAL groups ,SOIL moisture - Abstract
The Yellow River Delta (YRD) region is an important production base in Shandong Province. It encompasses an array of diversified crop systems, including the corn–wheat rotation system (Wheat–Corn), soybean–corn rotation system (Soybean–Corn), fruits or vegetables system (Fruit), cotton system (Cotton) and rice system (Rice). In this study, the communities of ammonia oxidizer–, denitrifier– and nitrogen (N)–fixing bacteria in those cropping systems were investigated by Illumina Miseq sequencing. We found that Rice soil exhibited significantly higher diversity indices of investigated N–cycling microbial communities than other crop soils, possibly due to its high soil water content. Wheat–Corn soils had higher abundances of nitrification gene amoA and denitrification genes nirK and nirS, and exhibited higher soil potential nitrification rate (PNR), compared with Soybean–Corn, Cotton and Fruit soils. Consistently, redundancy analysis (RDA) showed that soil water content (SWC), electrical conductivity (EC), and total nitrogen (TN) were the most important influencing factors of the diversity and structure of the investigated N–cycling microbial. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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16. Expansion of Dolomitic Rocks in TMAH and NaOH Solutions and Its Root Causes.
- Author
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Yuan, Huan, Deng, Min, Chen, Bi, Chen, Weifeng, and Mao, Zhongyang
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DOLOMITE ,EXPANSION & contraction of concrete ,ROCKS ,CONCRETE testing ,MICROSCOPY ,SCANNING electron microscopy - Abstract
In this paper, a tetramethylammonium hydroxide (TMAH) solution and homemade cement without alkali were used to eliminate the influence of the alkali-silica reaction (ASR) on the expansion of dolomitic rocks, and a NaOH solution was used as a comparison agent. The expansion of concrete microbars and dolomite powder compacts prepared from dolomitic rocks was tested. The expansion cracks and reaction products were investigated by X-ray diffraction, optical microscopy, scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The results showed that TMAH reacts with dolomite crystals in dolomitic rocks to form brucite and calcite. Through X-ray diffraction and SEM-EDS analysis, it can be determined that the chemical reaction between TMAH and dolomite crystal was dedolomitization. The expansion stress test and concrete microbar expansion test suggest that the alkali carbonate reaction (ACR) can produce expansion. Although both the ASR and the ACR were observed in the NaOH reaction system, but ASRgel was not found in the cracks, indicating that the ASR may be involved in the expansion process of concrete microbars and that the ACR is the root cause of the expansion. However, under the curing conditions of the TMAH solution, many ACR products were found around the crack, indicating that the expansion of the concrete in this system was caused entirely by the ACR. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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17. Differential Regulation of Anthocyanin Synthesis in Apple Peel under Different Sunlight Intensities.
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Chen, Weifeng, Zhang, Mengxia, Zhang, Guojing, Li, Pengmin, and Ma, Fengwang
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ANTHOCYANINS , *MICHAELIS-Menten equation , *SUNSHINE , *APPLES , *CYANIDIN , *FRUIT skins - Abstract
Sunlight radiation is a main environmental factor which affects anthocyanin synthesis. To clarify the regulatory mechanism of sunlight on the synthesis of anthocyanin in apple peel, bagged apples were exposed to diverse intensities of sunlight through different shading treatments. Under an increased solar ultraviolet-B (UV-B) light intensity, the concentration of anthocyanin in apple peels was consistent with the Michaelis–Menten equation. Under lower sunlight intensities, diphenyleneiodonium chloride (DPI, an inhibitor of plasma membrane NAD(P)H oxidase) treatment increased both the concentration of cyanidin-3-glycoside and the activity of dihydroflavonol 4-reductase (DFR). However, under higher sunlight intensities, DPI treatment decreased the concentrations of cyanidin-3-glycoside and quercetin-3-glycoside, as well as the activities of DFR and UDP-glycose: flavonoid 3-O-glycosyltransferase (UFGT). These results indicate that, under low sunlight intensity, anthocyanin synthesis in apple peel was limited by the supply of the substrate cyanidin, which was regulated by the DFR activity. Nevertheless, after exposure to high sunlight intensity, the anthocyanin produced in the apple peel was dependent on UFGT activity. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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18. Enhancement of Electrical Characteristics and Stability of Amorphous Si-Sn-O Thin Film Transistors with SiOx Passivation Layer.
- Author
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Liu, Xianzhe, Wu, Weijing, Chen, Weifeng, Ning, Honglong, Zhang, Xiaochen, Yuan, Weijian, Xiong, Mei, Wang, Xiaofeng, Yao, Rihui, and Peng, Junbiao
- Subjects
THIN film transistors ,ELECTRIC properties ,PASSIVATION ,CHEMICAL stability ,AMORPHOUS silicon ,ANNEALING of metals - Abstract
In this research, a passivated methodology was proposed for achieving good electrical characteristics for back-channel-etch (BCE) typed amorphous Si-Sn-O thin film transistors (a-STO TFTs). This methodology implied that the thermal annealing (i.e., pre-annealing) should be carried out before deposition of a SiO
x passivation layer. The pre-annealing played an important role in affecting device performance, which did get rid of the contamination of the lithography process. Simultaneously, the acceptor-like sub-gap density of states (DOS) of devices was extracted for further understanding the reason for improving device performance. It found that the SiOx layer could reduce DOS of the device and successfully protect the device from surroundings. Finally, a-STO TFT applied with this passivated methodology could possess good electrical properties including a saturation mobility of 4.2 ± 0.2 cm2 /V s, a low threshold voltage of 0.00 V, a large on/off current ratio of 6.94 × 108 , and a steep subthreshold swing of 0.23 V/decade. The threshold voltage slightly shifted under bias stresses and recovered itself to its initial state without any annealing procedure, which was attributed to the charge trapping in the bulk dielectric layers or interface. The results of this study indicate that a-STO TFT could be a robust candidate for realizing a large-size and high-resolution display. [ABSTRACT FROM AUTHOR]- Published
- 2018
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19. Effect of Source/Drain Electrodes on the Electrical Properties of Silicon–Tin Oxide Thin-Film Transistors.
- Author
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Liu, Xianzhe, Ning, Honglong, Chen, Weifeng, Yao, Rihui, Deng, Yuxi, Yuan, Weijian, Wu, Weijing, Peng, Junbiao, Fang, Zhiqiang, and Wang, Xiaofeng
- Subjects
ELECTRODES ,THIN film transistors - Abstract
Ultra-high definition displays have become a trend for the current flat plane displays. In this study, the contact properties of amorphous silicon–tin oxide thin-film transistors (a-STO TFTs) employed with source/drain (S/D) electrodes were analyzed. Ohmic contact with a good device performance was achieved when a-STO was matched with indium-tin-oxide (ITO) or Mo electrodes. The acceptor-like densities of trap states (DOS) of a-STO TFTs were further investigated by using low-frequency capacitance–voltage (C–V) characteristics to understand the impact of the electrode on the device performance. The reason of the distinct electrical performances of the devices with ITO and Mo contacts was attributed to different DOS caused by the generation of local defect states near the electrodes, which distorted the electric field distribution and formed an electrical potential barrier hindering the flow of electrons. It is of significant importance for circuit designers to design reliable integrated circuits with SnO
2 -based devices applied in flat panel displays. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
20. A Monocular-Visual SLAM System with Semantic and Optical-Flow Fusion for Indoor Dynamic Environments.
- Author
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Chen W, Shang G, Hu K, Zhou C, Wang X, Fang G, and Ji A
- Abstract
A static environment is a prerequisite for the stable operation of most visual SLAM systems, which limits the practical use of most existing systems. The robustness and accuracy of visual SLAM systems in dynamic environments still face many complex challenges. Only relying on semantic information or geometric methods cannot filter out dynamic feature points well. Considering the problem of dynamic objects easily interfering with the localization accuracy of SLAM systems, this paper proposes a new monocular SLAM algorithm for use in dynamic environments. This improved algorithm combines semantic information and geometric methods to filter out dynamic feature points. Firstly, an adjusted Mask R-CNN removes prior highly dynamic objects. The remaining feature-point pairs are matched via the optical-flow method and a fundamental matrix is calculated using those matched feature-point pairs. Then, the environment's actual dynamic feature points are filtered out using the polar geometric constraint. The improved system can effectively filter out the feature points of dynamic targets. Finally, our experimental results on the TUM RGB-D and Bonn RGB-D Dynamic datasets showed that the proposed method could improve the pose estimation accuracy of a SLAM system in a dynamic environment, especially in the case of high indoor dynamics. The performance effect was better than that of the existing ORB-SLAM2. It also had a higher running speed than DynaSLAM, which is a similar dynamic visual SLAM algorithm.
- Published
- 2022
- Full Text
- View/download PDF
21. Enhancement of Electrical Characteristics and Stability of Amorphous Si-Sn-O Thin Film Transistors with SiO x Passivation Layer.
- Author
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Liu X, Wu W, Chen W, Ning H, Zhang X, Yuan W, Xiong M, Wang X, Yao R, and Peng J
- Abstract
In this research, a passivated methodology was proposed for achieving good electrical characteristics for back-channel-etch (BCE) typed amorphous Si-Sn-O thin film transistors (a-STO TFTs). This methodology implied that the thermal annealing (i.e., pre-annealing) should be carried out before deposition of a SiO
x passivation layer. The pre-annealing played an important role in affecting device performance, which did get rid of the contamination of the lithography process. Simultaneously, the acceptor-like sub-gap density of states (DOS) of devices was extracted for further understanding the reason for improving device performance. It found that the SiOx layer could reduce DOS of the device and successfully protect the device from surroundings. Finally, a-STO TFT applied with this passivated methodology could possess good electrical properties including a saturation mobility of 4.2 ± 0.2 cm²/V s, a low threshold voltage of 0.00 V, a large on/off current ratio of 6.94 × 10⁸, and a steep subthreshold swing of 0.23 V/decade. The threshold voltage slightly shifted under bias stresses and recovered itself to its initial state without any annealing procedure, which was attributed to the charge trapping in the bulk dielectric layers or interface. The results of this study indicate that a-STO TFT could be a robust candidate for realizing a large-size and high-resolution display.- Published
- 2018
- Full Text
- View/download PDF
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