SeaWiFS imagery as a tool to detect three-dimensional structure of suspended sediment in estuarine fronts, a case study on the Pearl River

Li, Yan,Deng, Ming 대한원격탐사학회 2000 International Symposium on Remote Sensing Vol.16 No.1

A feasible remote sensing algorithm to estimate the three-dimensional distribution of suspended sediment was developed under a new approach. This algorithm brings back suspended sediment concentration (SSC) in certain water layers using water-leaving reflection reflected by bands of SeaWiFS. Penetration depths and suspended sediment concentration could be determined by the gradient of satellite-detected reflectance spectrum. And then the SSC in certain water layers could be calculated by penetration depth and suspended sediment concentration for such two penetration depths. Some interesting information about vertical structure was provides in the upper layer of water column along the estuarine front. SeaWiFS's retrieved images for near surface 3D structure of SSC suggests, for the Pearl River estuary in wet season of 1999, an unusual belt of suspended sediment appears along the estuarine front. In upstream side of that belt, SSC for layer 20~50cm is lower than the most surface layer. While in its downstream side, SSC for layer 50cm clearly gets higher.

Lrfn2-Mutant Mice Display Suppressed Synaptic Plasticity and Inhibitory Synapse Development and Abnormal Social Communication and Startle Response

Li, Yan,Kim, Ryunhee,Cho, Yi Sul,Song, Woo Seok,Kim, Doyoun,Kim, Kyungdeok,Roh, Junyeop Daniel,Chung, Changuk,Park, Hanwool,Yang, Esther,Kim, Soo-Jeong,Ko, Jaewon,Kim, Hyun,Kim, Myoung-Hwan,Bae, Yong- Society for Neuroscience 2018 The Journal of neuroscience Vol.38 No.26

<P>SALM1 (SALM (synaptic adhesion-like molecule), also known as LRFN2 (leucine rich repeat and fibronectin type III domain containing), is a postsynaptic density (PSD)-95-interacting synaptic adhesion molecule implicated in the regulation of NMDA receptor (NMDAR) clustering largely based on in vitro data, although its in vivo functions remain unclear. Here, we found that mice lacking SALM1/LRFN2 (Lrfn2(-/-) mice) show a normal density of excitatory synapses but altered excitatory synaptic function, including enhanced NMDAR-dependent synaptic transmission but suppressed NMDAR-dependent synaptic plasticity in the hippocampal CA1 region. Unexpectedly, SALM1expression was detected in both glutamatergic and GABAergic neurons and Lrfn2(-/-) CA1 pyramidal neurons showed decreases in the density of inhibitory synapses and the frequency of spontaneous inhibitory synaptic transmission. Behaviorally, ultrasonic vocalization was suppressed in Lrfn2(-/-) pups separated from their mothers and acoustic startle was enhanced, but locomotion, anxiety-like behavior, social interaction, repetitive behaviors, and learning and memory were largely normal in adult male Lrfn2(-/-) mice. These results suggest that SALM1/LRFN2 regulates excitatory synapse function, inhibitory synapse development, and social communication and startle behaviors in mice.</P>

Loss Analysis and Soft-Switching Behavior of Flyback-Forward High Gain DC/DC Converters with a GaN FET

Li, Yan,Zheng, Trillion Q.,Zhang, Yajing,Cui, Meiting,Han, Yang,Dou, Wei The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.1

Compared with Si MOSFETs, the GaN FET has many advantages in a wide band gap, high saturation drift velocity, high critical breakdown field, etc. This paper compares the electrical properties of GaN FETs and Si MOSFETs. The soft-switching condition and power loss analysis in a flyback-forward high gain DC/DC converter with a GaN FET is presented in detail. In addition, a comparison between GaN diodes and Si diodes is made. Finally, a 200W GaN FET based flyback-forward high gain DC/DC converter is established, and experimental results verify that the GaN FET is superior to the Si MOSFET in terms of switching characteristics and efficiency. They also show that the GaN diode is better than the Si diode when it comes to reverse recovery characteristics.

Phylogenetic and functional analysis of TGF-β/Smad2 pathway genes in cotton bollworm, Helicoverpa armigera

Li Yan,Lu Qin,Luo Hailing,Xia Shunchao,Li Haiyin,Xu Weihua 한국응용곤충학회 2021 Journal of Asia-Pacific Entomology Vol.24 No.4

Transforming growth factor-beta (TGF-β) signaling pathway plays important roles in embryonic development, cell proliferation and tissue differentiation in vertebrates. Our previous studies demonstrated that TGF-β signal activates Smad1-POU-TFAM and PP2A-Akt pathways to regulate pupal diapause in Helicoverpa armigera. In this study, we investigated the function of TGF-β activates Smad2 pathway in H. armigera. Phylogenetic analysis of H. armigera TGF-β receptor I (TGFβRI), Smad2, Smad4 genes showed high conservation across species. In vitro experiments showed that TGFβRI was localized in the cell membrane where it binds Smad2 leading to the phosphorylation of Smad2. Smad4 was mainly localized in the cytoplasm, and bind to Smad2. Protein expression analysis showed that expression of TGFβRI, Smad4, Smad2, p-Smad2 were lower in diapause-destined pupae compared with nondiapause-destined pupae. Notably, treatment with 20-hydroxyecdysone (20E) increased expression of the above proteins. Inhibition of TGF-β/Smad2 signaling pathway delayed pupal development. These findings indicate that TGF-β/Smad2 pathway is involved in pupal development or diapause in H. armigera.

Extraction of visual texture features of seabed sediments using an SVDD approach

Li, Yan,Liu, Shijie,Zhu, Puqiang,Yu, Jiancheng,Li, Shuo Pergamon Press 2017 Ocean engineering Vol.142 No.-

<P><B>Abstract</B></P> <P>Perception of the seabed environment is an important capability of autonomous underwater vehicles. This paper focuses on defining and extracting robust texture features from visual images that lead to useful and practical automated identification of the types of seabed sediments. The visual texture features are described by using a gray-level co-occurrence matrix (GLCM) and fractal dimension, after which an unsupervised learning method, self-organizing map (SOM), is adopted to evaluate the validity of features descriptors on three types of seabed sediments. Subsequently, a kernel-based approach that exhibits robustness versus low numbers of high-dimensional samples, named support vector domain description (SVDD), is applied to classify the types of seabed sediments. In comparison with state-of-the-art classifiers, the experimental results demonstrated the effectiveness of the SVDD on the classification of seabed sediments.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The visual images of seabed sediments are characterized by the texture features which are extracted based on the GLCM and fractal theory. </LI> <LI> A multi-class classification strategy for seabed sediments is proposed by adding a distance measure after SVDD implementation. </LI> <LI> The experimental results demonstrate that the proposed classification strategy is feasible in recognizing the type of seabed sediments. </LI> </UL> </P>

Effects of dandelion (Taraxacum sp.,) supplements on lactation performance, antioxidative activity, and plasma metabolome in primiparous dairy cows

Li Yan,Mei Jie,Wang Jiaqi,Liu Hongyun 아세아·태평양축산학회 2023 Animal Bioscience Vol.36 No.2

Objective: This study evaluated the effects of dandelion supplements on lactation performance, circulating antioxidative activity and plasma metabolomics in primiparous dairy cows. Methods: A total of 60 mid-lactation dairy cows (milk yield = 34.29±0.34 kg/d; days in milk = 151.72±2.36 days) were divided into 4 treatment groups randomly, comprising the addition of dandelion at 0, 100, 200, 400 g/d per head. The experiment lasted for 8 weeks with an extra 10 days’ pre-feeding period. Milk and blood samples were collected, and plasma samples were selected to perform metabolomics analysis. Results: Supplementing 200 g/d of dandelion increased the yield of milk and lactose (p≤ 0.05). The milk somatic cell counts (p≤0.05) were lower in all dandelion groups than those in the control group. The activity of glutathione peroxidase (p≤0.05) and superoxide dismutase (p≤0.05) were increased and plasma malondialdehyde (p = 0.01) was decreased when cows were fed 200 g/d dandelion. Plasma metabolomics analysis showed that 23 hub differential metabolites were identified in the 200 g/d dandelion group. These metabolites such as ribose, glutamic acid, valine, and phenylalanine were enriched in D-glutamine and D-glutamate metabolism (p = 0.06, impact value = 1), phenylalanine, tyrosine, and tryptophan biosynthesis (p = 0.05, impact value = 0.5), and starch and sucrose metabolism (p = 0.21, impact value = 0.13). Moreover, correlation analysis showed that circulating ribose, mannose, and glutamic acid were positively related to milk yield. Conclusion: Dandelion supplementation could improve lactation performance and elevate the plasma carbohydrate and amino acids metabolism and antioxidative activity. Supplementation of 200 g/d dandelion is recommended for lactating dairy cows.

Gauss sums over some matrix groups

Li, Yan,Hu, Su Elsevier 2012 Journal of number theory Vol.132 No.12

<P><B>Abstract</B></P> <P>In this note, we give explicit expressions of Gauss sums for general (resp. special) linear groups over finite fields, which involve classical Gauss sums (resp. Kloosterman sums). The key ingredient is averaging such sums over Borel subgroups, i.e., the groups of upper triangular matrices. As applications, we count the number of invertible matrices of zero-trace over finite fields and we also improve two bounds of Ferguson, Hoffman, Luca, Ostafe and Shparlinski in [R. Ferguson, C. Hoffman, F. Luca, A. Ostafe, I.E. Shparlinski, Some additive combinatorics problems in matrix rings, Rev. Mat. Complut. 23 (2010) 501–513].</P>

Multimode Hybrid Control Strategy of LLC Resonant Converter in Applications with Wide Input Voltage Range

Li, Yan,Zhang, Kun,Yang, Shuaifei The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.1

This paper proposes a multimode hybrid control strategy that can achieve zero-voltage switching of primary switches and zero-current switching of secondary rectifier diodes in a wide input voltage range for full-bridge LLC resonant converters. When the input voltage is lower than the rated voltage, the converter operates in Mode 1 through the variable-frequency control strategy. When the input voltage is higher than the rated voltage, the converter operates in Mode 2 through the VF and phase-shift control strategy until the switching frequency reaches the upper limit. Then, the converter operates in Mode 3 through the constant-frequency and phase-shift control strategy. The secondary-side diode current will operate in the discontinuous current mode in Modes 1 and 3, whereas it will operate in the boundary current mode in Mode 2. The current RMS value and conduction loss can be reduced in Mode 2. A detailed theoretical analysis of the operation principle, the voltage gain characteristics, and the realization method is presented in this paper. Finally, a 500 W prototype with 100-200 V input voltage and 40 V output voltage is built to verify the feasibility of the multimode hybrid control strategy.

외국인 유학생 대학입학 전형 정책에 대한 연구 -4년제 대학 학부 신입생의 한국어능력을 중심으로-

LI YAN 국제한국어교육학회 2019 한국어 교육 Vol.30 No.1

The purpose of this study is to analyze the relation between college admission policies for international students and their Korean language proficiency, and the relation between admission policies related to Korean language proficiency and Korean language education of Korean learners for academic purposes. Admission policies related to Korean language proficiency are very important to international candidates, so in order to recruit international students more effectively, universities define and implement their own admission policies. However, not only the contents of these policies are very complicated, but also universities’ policies are very different, so there is a need to conduct further research. Moreover, these admission policies will have a great impact on the Korean language education of learners for academic purposes, so it is also necessary to do a research to analyze this. Considering such factors as the number of students, policies’ typicality and diversity, ten four-year universities’ admission policies are chosen as the research object. In this study, admission policies’ content and characteristics are analyzed separately. And on the basis of the analysis results, the implications for Korean language education are suggested.

A Novel Hybrid Active Power Filter with a High-Voltage Rank

Li, Yan,Li, Gang The Korean Institute of Power Electronics 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.4

A novel hybrid active power filter (NHAPF) that can be adopted in high-voltage systems is proposed in this paper. The topological structure and filtering principle of the compensating system is provided and analyzed, respectively. Different controlling strategies are also presented to select the suitable strategy for the compensation system. Based on the selected strategy, the harmonic suppression function is used to analyze the influence of system parameters on the compensating system with MATLAB. Moreover, parameters in the injection branch are designed and analyzed. The performance of the proposed NHAPF in harmonic suppression and reactive power compensation is simulated with PSim. Thereafter, the overall control method is proposed. Simulation analysis and real experiments show that the proposed NHAPF exhibits good harmonic suppression and reactive power compensation. The proposed compensated system is based on the three-phase four-switch inverter, which is inexpensive, and the control method is verified for validity and effectiveness.