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An Integrated Shadow-Adjusted Snow-Aging Index for Alpine Regions

Haixing Li, Jinrong Liu, Xiangxu Bu, Xuezhi Feng, Pengfeng Xiao
2020 Remote Sensing  
Detecting the variations in snow cover aging over undulating alpine regions is challenging owing to the complex snow-aging process and shadow effect from steep slopes. This study proposes a novel snow-cover status index, namely shadow-adjusted snow-aging index (SASAI), portraying the integrated aging process within the Manas River Basin in northwest China. The Environment Satellites HJ-1A/B optical images and in-field measurements were used during the snow ablation and accumulation periods. The
more » ... in-field measurements provide a reference for building a candidate library of snow-aging indicators. The representative aging samples for training and validation were obtained using the proposed time-gap searching method combined with the target zones established based on the altitude of snowline. An analytic hierarchy process was used to determine the snow-aging index (SAI) using multiple optimal snow-aging indicators. After correction by the extreme value optimization algorithm, the SASAI was finally corrected for the effects of shading and assessed. This study provides both a flexible algorithm that indicates the characteristics of snow aging and speculation on the causes of the aging process. The separability of the SAI/SASAI and adaptability of this algorithm on multiperiod remote sensing images further demonstrates the applicability of the SASAI to all the alpine regions.
doi:10.3390/rs12081249 fatcat:p3eabl4lnbamfbsghyzdvnhtxm

Detecting Snowfall Events over Mountainous Areas Using Optical Imagery

Jiangeng Wang, Yonghong Zhang, Yinyi Cheng, Xueliang Zhang, Xuezhi Feng, Wei Huang, Hao Zhou
2018 Water  
Snowfall over mountainous areas not only has important implications on the water cycle and the Earth's radiation balance, but also causes potentially hazardous weather. However, snowfall detection remains one of the most difficult problems in modern hydrometeorology. We present a method for detecting snowfall events from optical satellite data for seasonal snow in mountainous areas. The proposed methodology is based on identifying expanded snow cover or suddenly declined snow grain size using
more » ... me series images, from which it is possible to detect the location and time of snowfall events. The methodology was tested with Moderate Resolution Imaging Spectroradiometer (MODIS) daily radiance data for an entire hydrologic year from July 2014 to June 2015 in the mountainous area of the Manas River Basin, Northwest China. The study evaluated the recordings of precipitation events at eighteen meteorological stations in the study area prove the effectiveness of the proposed method, showing that there was more liquid precipitation in the second and third quarter, and more solid precipitation in the first and fourth quarter.
doi:10.3390/w10111514 fatcat:btilyov22zftpk3vn4ukq66ccu

Abscisic acid-enhanced starch accumulation of bioenergy crop duckweed (Spirodela polyrrhiza)

Xuezhi Wang, Weihua Cui, Weiwu Hu, Chuanping Feng
2020 RSC Advances  
This study demonstrates that abscisic acid (ABA) induced enhanced starch accumulation in duckweed Spirodela polyrrhiza. ABA up-regulates the expression of the APL2 gene which enhances the AGPase activity and results in larger and more starch granules in the duckweed fronds.
doi:10.1039/d0ra00269k pmid:35492951 pmcid:PMC9050358 fatcat:b7orsmn7sbhqrdfw62fcjtuijy

The Methods and Application of Automatically Extracting Stream Network of Watershed

LI Changfeng, FENG Xuezhi, ZHAO Rui
2003 Journal of Lake Sciences  
doi:10.18307/2003.0303 fatcat:se2iigkxfrbtdhs6b3hsox5eba

BSCL2/seipin regulates adipogenesis through actin cytoskeleton remodelling

Wulin Yang, Shermaine Thein, Xiaorui Wang, Xuezhi Bi, Russell E. Ericksen, Feng Xu, Weiping Han
2013 Human Molecular Genetics  
Seipin regulates lipid homeostasis by preventing lipid droplet (LD) formation in non-adipocytes but promoting it in developing adipocytes. Here, we report that seipin interacts with 14-3-3b through its N-and C-termini. Expression of 14-3-3b is upregulated during adipogenesis, and its deletion results in defective adipogenesis without affecting key adipogenic transcription factors. We further identified the actin-severing protein cofilin-1 as an interacting partner to 14-3-3b. Cofilin-1 was
more » ... otemporally recruited by 14-3-3b in the cytoplasm during adipocyte differentiation. Extensive actin cytoskeleton remodelling, from stress fibres to cortical structures, was apparent during adipogenesis, but not under lipogenic conditions, indicating that actin cytoskeleton remodelling is only required for adipocyte development. Similar to seipin and 14-3-3b, cofilin-1 knockdown led to impaired adipocyte development. At the cellular level, differentiated cells with knockdown of cofilin-1, 14-3-3b or seipin continued to maintain relatively intact stress fibres, in contrast to cortical actin structure in control cells. Finally, 3T3-L1 cells expressing a severing-resistant actin mutant exhibited impaired adipogenesis. We propose that seipin regulates adipogenesis by recruiting cofilin-1 to remodel actin cytoskeleton through the 14-3-3b protein.
doi:10.1093/hmg/ddt444 pmid:24026679 fatcat:hdxfi4wyazfxdlto7pignsml2m

Multiscale Optimized Segmentation of Urban Green Cover in High Resolution Remote Sensing Image

Pengfeng Xiao, Xueliang Zhang, Hongmin Zhang, Rui Hu, Xuezhi Feng
2018 Remote Sensing  
The urban green cover in high-spatial resolution (HR) remote sensing images have obvious multiscale characteristics, it is thus not possible to properly segment all features using a single segmentation scale because over-segmentation or under-segmentation often occurs. In this study, an unsupervised cross-scale optimization method specifically for urban green cover segmentation is proposed. A global optimal segmentation is first selected from multiscale segmentation results by using an
more » ... ion indicator. The regions in the global optimal segmentation are then isolated into under- and fine-segmentation parts. The under-segmentation regions are further locally refined by using the same indicator as that in global optimization. Finally, the fine-segmentation part and the refined under-segmentation part are combined to obtain the final cross-scale optimized result. The green cover objects can be segmented at their specific optimal segmentation scales in the optimized segmentation result to reduce both under- and over-segmentation errors. Experimental results on two test HR datasets verify the effectiveness of the proposed method.
doi:10.3390/rs10111813 fatcat:leq2sigl3jbw3ptviiwnzh3mfe

Fully Convolutional Pyramidal Networks for Semantic Segmentation (November 2020)

Fengxiao Li, Zourong Long, Peng He, Peng Feng, Xiaodong Guo, Xuezhi Ren, Biao Wei, Mingfu Zhao, Bin Tang
2020 IEEE Access  
doi:10.1109/access.2020.3045280 fatcat:se5g62zdg5b27aufqpwebw74zy

Visual Map Construction Using RGB-D Sensors for Image-Based Localization in Indoor Environments

Guanyuan Feng, Lin Ma, Xuezhi Tan
2017 Journal of Sensors  
RGB-D sensors capture RGB images and depth images simultaneously, which makes it possible to acquire the depth information at pixel level. This paper focuses on the use of RGB-D sensors to construct a visual map which is an extended dense 3D map containing essential elements for image-based localization, such as poses of the database camera, visual features, and 3D structures of the building. Taking advantage of matched visual features and corresponding depth values, a novel local optimization
more » ... lgorithm is proposed to achieve point cloud registration and database camera pose estimation. Next, graph-based optimization is used to obtain the global consistency of the map. On the basis of the visual map, the image-based localization method is investigated, making use of the epipolar constraint. The performance of the visual map construction and the image-based localization are evaluated on typical indoor scenes. The simulation results show that the average position errors of the database camera and the query camera can be limited to within 0.2 meters and 0.9 meters, respectively.
doi:10.1155/2017/8037607 fatcat:y6twx3uvv5bg3pmlfx77otkryq

Monitoring cyanobacteria bloom based on MODIS data in Lake Taihu

ZHOU Liguo, FENG Xuezhi, WANG Chunhong, WANG Deyu, XU Xiaoxiong
2008 Journal of Lake Sciences  
This paper discusses the method and mechanism of identifying and monitoring the cyanobacteria bloom based on MODIS data in Lake Taihu. Through the comparison of spectral reflectance value of different cyanobacteria concentration, it can be found that several wave bands are sensitive to cyanobacteria. Making use of the color composition, we can get the macroscopic distribution information of the cyanobacteria bloom. Furthermore, using the ratio index model, we can further confine the relative
more » ... tent of the cyanobacteria bloom. Finally through overlaying analysis of the cyanobacteria concentration distribution from multi-temporal MODIS data, dynamic changing information of cyanobacteria bloom can be obtained.
doi:10.18307/2008.0211 fatcat:jf47uwlienazrputgniuslm2gi

Early results after surgical treatment of left Ventricular Aneurysm

Xisheng Wang, Xuezhi He, Yunqing Mei, Qiang Ji, Jing Feng, Jianzhi Cai, Yifeng Sun, Shiliang Xie
2012 Journal of Cardiothoracic Surgery  
Left ventricular aneurysm (LVA) is a serious complication of myocardial infarction and reduces the chances of survival. Controversy still exists regarding the optimal surgical technique for LVA repair. We analyze the efficacy of two techniques, linear vs. endoventricular circular patch plasty, for repair of LVA and the efficacy of surgical ventricular restoration (SVR) on beating heart. Methods: This study included 62 patients who underwent SVR from 1086 consecutive patients were subjected to
more » ... ronary artery bypass grafting (CABG) between 2000 and 2009. All selected patients were divided either into group liner or patch according to the choice of the repair technique depended on factors such as localization, size and dimension of the scar. The patients also were divided either into group beating heart or cardioplegia. The pre-, intra-and postoperative relevant data of all selected patients were analyzed. Results: The mortality was not significantly different between linear and patch repair groups, also the actuarial survival rates within 24 months (p= 0.529). Postoperative echocardiographic findings showed significant improvements in left ventricular function in both groups. The beating heart technique reduced postoperative peak release by 27% for Cardiac troponin I (cTnI) compared with the cardioplegia group (0.46 ± 0.06 ng/mL versus 0.63 ± 0.09 ng/mL, p= 0.004), and increased the perioperative survival by 9% (97.2% versus 88.5%), but the actuarial survival rates were not significantly different between the groups from 2 to 24 months (p= 0.151). Conclusions: Both techniques (linear and patch) achieved good results with respect to mortality, functional status and survival. The choice of surgical technique should be adapted in each patient. The beating heart technique may to some extent relieve myocardial injury in patients undergoing SVR.
doi:10.1186/1749-8090-7-126 pmid:23171698 pmcid:PMC3527346 fatcat:qmkkin2l4rhhpbsncblc35lj3i

Ambulatory blood pressure monitoring in children with obstructive sleep apnea syndrome

Xuezhi Geng, Yunxiao Wu, Wentong Ge, Guoshuang Feng, Li Zheng, Zhifei Xu, Xin Ni
2019 Pediatric Investigation  
The incidence of obstructive sleep apnea syndrome (OSAS) in children has increased year by year recently. Blood pressure research of OSAS children can help understand the occurrence of OSAS related complications. Early detection and intervention of blood pressure changes in children with OSAS can reduce the incidence of cardiovascular disease in later adulthood. To investigate the differences in blood pressure among different groups of snoring children and different sleep stages. Habitually
more » ... ing children (snoring frequency of ≥ 3 nights per week) aged 3 to 11 years were recruited from Beijing Children's Hospital from 1 January 2017 to 30 June 2018. All children underwent polysomnography, and their blood pressure was monitored and calculated by the pulse transit time. The children were divided into those with primary snoring (PS), mild OSAS, and moderate to severe OSAS according to their obstructive apnea-hypopnea index (OAHI). In total, 140 children were included. Ninety-seven had PS, 24 had mild OSAS, and 19 had moderate to severe OSAS. There were no differences in age, sex, or body mass index z-score among the groups. Statistically significant differences were found in the OAHI, oxygen desaturation index 3%, respiratory arousal index, and lowest oxygen saturation among the three groups. Children with moderate to severe OSAS had higher systolic and diastolic blood pressure than those with mild OSAS and PS (P < 0.001). In all children, systolic and diastolic blood pressure was higher in the rapid eye movement (REM) sleep stage than in the non-REM sleep stage (P < 0.05). Children with moderate to severe OSAS had higher blood pressure than those with PS and mild OSAS in all sleep stages. Blood pressure in the REM sleep stage was higher than that in other sleep stages in all groups of children.
doi:10.1002/ped4.12163 pmid:32851326 pmcid:PMC7331368 fatcat:wthuv3iglngclemb2aelw7icp4

Effective Compositing Method to Produce Cloud-Free AVHRR Image

Lingxiao Wang, Pengfeng Xiao, Xuezhi Feng, Haixing Li, Wenbo Zhang, Jintang Lin
2014 IEEE Geoscience and Remote Sensing Letters  
Feng, H. Li, W. Zhang, and J. Lin are with the Department of Geographic Information Science, Nanjing University, Nanjing 210093, China (e-mail: xiaopf@gmail.com).  ... 
doi:10.1109/lgrs.2013.2257672 fatcat:svo7wkz67vak5mq34we3bqzu4q

Spatial and Temporal Characteristics of Snow Cover in the Tizinafu Watershed of the Western Kunlun Mountains

Jiangfeng She, Yufang Zhang, Xingong Li, Xuezhi Feng
2015 Remote Sensing  
The Tizinafu watershed has a complex mountainous terrain in the western Kunlun Mountains; little study has been done on the spatial and temporal characteristics of snow cover in the region. Daily snow cover data of 10 hydrological years (October 2002 to September 2012 in the watershed were generated by combining MODIS Terra (MOD10A1) and Aqua (MYD10A1) snow cover products and employing a nine-day temporal filter for cloud reduction. The accuracy and window size of the temporal filter were
more » ... ed using a simulation approach. Spatial and temporal characteristics of snow cover in the watershed were then analyzed. Our results showed that snow generally starts melting in March and reaches the minimum in early August in the watershed. Snow cover percentages (SCPs) in all five elevation zones increase consistently with the rise of elevation. Slope doesn't play a major role in snow cover distribution when it exceeds 10°. The largest SCP difference is between the south and the other aspects and occurs between mid-October and mid-November with decreasing SCP, indicating direct solar radiation may cause the reduction of snow cover. While both the mean snow cover durations (SCDs) of the hydrological years and of the snowmelt seasons share a similar spatial pattern to the topography of the watershed, the coefficient of variation of the SCDs exhibits an opposite spatial distribution. There is a significant correlation between annual mean SCP and annual total stream flow, indicating that snowmelt is a major source of stream runoff that might be predictable with SCP. OPEN ACCESS Remote Sens. 2015, 7 3427
doi:10.3390/rs70403426 fatcat:3wnpjsz7znexpksywa2qwvi5mi

Drift-Aware Monocular Localization Based on a Pre-Constructed Dense 3D Map in Indoor Environments

Guanyuan Feng, Lin Ma, Xuezhi Tan, Danyang Qin
2018 ISPRS International Journal of Geo-Information  
Recently, monocular localization has attracted increased attention due to its application to indoor navigation and augmented reality. In this paper, a drift-aware monocular localization system that performs global and local localization is presented based on a pre-constructed dense three-dimensional (3D) map. In global localization, a pixel-distance weighted least squares algorithm is investigated for calculating the absolute scale for the epipolar constraint. To reduce the accumulative errors
more » ... hat are caused by the relative position estimation, a map interaction-based drift detection method is introduced in local localization, and the drift distance is computed by the proposed line model-based maximum likelihood estimation sample consensus (MLESAC) algorithm. The line model contains a fitted line segment and some visual feature points, which are used to seek inliers of the estimated feature points for drift detection. Taking advantage of the drift detection method, the monocular localization system switches between the global and local localization modes, which effectively keeps the position errors within an expected range. The performance of the proposed monocular localization system is evaluated on typical indoor scenes, and experimental results show that compared with the existing localization methods, the accuracy improvement rates of the absolute position estimation and the relative position estimation are at least 30.09% and 65.59%, respectively.
doi:10.3390/ijgi7080299 fatcat:jram2ws66ng3nelfccwf4be5wa

Nitrate Removal from Actual Wastewater by Coupling Sulfur-Based Autotrophic and Heterotrophic Denitrification under Different Influent Concentrations

Feng Liu, Suqin Wang, Xuezhi Zhang, Feiyue Qian, Yaobing Wang, Yao Yin
2021 Water  
Contamination of wastewater with organic-limited nitrates has become an urgent problem in wastewater treatment. The cooperating heterotrophic with sulfur autotrophic denitrification is an alternative process and the efficiency has been assessed in many studies treating simulated wastewater under different operating conditions. However, due to the complex and diverse nature of actual wastewater, more studies treating actual wastewater are still needed to evaluate the feasibility of collaborative
more » ... denitrification. In this study, lab-scale experiments were performed with actual nitrate polluted water of two different concentrations, with glucose and sodium thiosulfate introduced as mixed electron donors in the coupling sulfur-based autotrophic and heterotrophic denitrification. Results showed that the optimum denitrification performance was exhibited when the influent substrate mass ratio of C/N/S was 1.3/1/1.9, with a maximum denitrification rate of 3.52 kg NO3−-N/(m3 day) and nitrate removal efficiency of 93% in the coupled systems. Illumina high-throughput sequencing analysis revealed that autotrophic, facultative, and heterotrophic bacteria jointly contributed to high nitrogen removal efficiency. The autotrophic denitrification maintained as the predominant process, while the second most prevalent denitrification process gradually changed from heterotrophic to facultative with the increase of influent concentration at optimum C/N/S ratio conditions. Furthermore, the initiation of dissimilatory nitrate reduction to ammonium (DNRA) was very pivotal in promoting the entire denitrification process. These results suggested that sulfur-based autotrophic coupled with heterotrophic denitrifying process is an alternative and promising method to treat nitrate containing wastewater.
doi:10.3390/w13202913 fatcat:maqeto6whbgonewzaoscodihum
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