Accumulated Nitrogen Recovery and its Application in Wheat-Maize Cropping Systems

Yibing Ma,Jie Liu,Jumei Li 한국토양비료학회 2014 한국토양비료학회 학술발표회 초록집 Vol.2014 No.6

Communication Modulation Signal Recognition Algorithm Based on Entropy Cloud Characteristics

Yibing Li,Jie Chen,Dandan Liu,Jingchao Li 보안공학연구지원센터 2016 International Journal of Signal Processing, Image Vol.9 No.5

Communication modulation signal recognition, as an emerging technology, has been widely used in the field of communication reconnaissance. It is generally known that the characteristics of communication modulation signals under low SNR environment is difficult to extract. To solve this problem, a novel modulation signal feature extraction algorithm based on entropy cloud characteristics is put forward in three steps by this paper. Firstly, it extracts entropy characteristics of the modification signal, which introduce the exponential entropy to construct two-dimensional feature entropy with shannon and exponential entropy for a better signal recognition performance. Then, it extracts cloud digital characteristics of information entropy to build three-dimensional feature, which can depict the modulation type characteristics of the signal. Finally, it uses grey correlation classifier for signal identification. By means of simulation, it can be seen that the new algorithm has overcome the defection that signal characteristics are unstable and difficult to extract under low SNR environment in the traditional method. So the new algorithm is available and effective for the signal identification under low SNR environment, thus achieves the goal of the signal classification.

Investigation on aerodynamic instability of high-voltage transmission lines under rain-wind condition

Chao Zhou,Yibing Liu,Zhiyong Ma 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.1

Under rain-wind conditions, rain-wind induced aerodynamic instability phenomenon often occurs on high-voltage transmission lines. Like the effects of any other oscillations, this kind of vibration intensifies the fatigue of high-voltage conductors, especially on line supportsor clamps. The presence of raindrops and wind associated with electric field maybe the main cause of this phenomenon. On rainydays, raindrops hit the transmission line and suspends to the high-voltage conductor. The suspended raindrops form upper rivulet andlower rivulet and take an elliptical arch shape along the surface of the high-voltage conductor by action of the wind, if rainfall is sufficient. Moreover, the rivulets are enlarged as a cone shape with the electric field of high-voltage conductor. The upper rivulet’s effect onthe original cross-section formation of the high-voltage conductor and its movement are likely to be the cause of aerodynamic instability. The objective of this paper is to validate a two-dimensional model to investigate the effects of different parameters (electric field strength,wind velocity, frequency and damping ratio of the dynamic system) on aerodynamic stability of the conductor. The Lyapunov stabilitytheory is applied to the model to derive the criterion for the instable angle of the rivulet. Moreover, an experimental conductor modelwith a moveable artificial upper rivulet is set-up and tested in a wind tunnel. The theoretical results are in good agreement with the experimentaldata. The model enable better comprehension of the rain-wind induced aerodynamic instability on the conductor.

Leakage detection for hydraulic IGV system in gas turbine compressor with recursive ridge regression estimation

Xin Wu,Yibing Liu 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.10

The failure of the hydraulic Inlet guide vane (IGV) system needs to be avoided in the gas turbine compressor, since the IGV system is critical for the function and efficiency of the gas turbine and its fault can even cause the gas turbine to jump off the power grid. This paper investigates the detection of external and internal leakages, whose levels can be represented through corresponding leakage coefficients, at the cylinder in the hydraulic IGV system. Based on the dynamic model, we propose the recursive ridge regression parameter estimation method to detect and isolate different leakage coefficients under varying load. The developed algorithm is verified through experiments in a hydraulic IGV emulator. Based on experimental results, the proposed scheme can estimate leakage coefficients with good performance.

Modeling and numerical analysis of corona-induced vibration on High-voltage transmission line with raindrops

Chao Zhou,Yibing Liu,Yan-ping Liu 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.11

In rainy days, rainfall hitting high-voltage transmission lines forms raindrops that suspended to lower surface of the conductors. Thesuspended raindrops subjected to electric field take a cone shape, which leads to a drastic increase in local electric field and amplifies thecorona discharge. Electrostatic attractive force between the conductor and the ground is partially shielded by space charge during thecorona discharge. Intermittent shielding and the time lags may be the main causes of this phenomenon namely corona-induced vibration. Like any other mechanical oscillations, this kind of vibration may result in fatigue damages of conductors, failures of insulator stringsand spacers. This paper is to validate a numerical model based on the finite element method and Newmark algorithm to reveal the formationmechanism of the corona-induced vibrations. According to the numerical model, the effect of rain intensity, electric field and appliedvoltage on vibration amplitudes and natural frequency are systematically investigated. The results agree well with experimental dataavailable in the literature. The model and numerical analysis method enable a better comprehension of the formation mechanism of thecorona-induced vibrations.

Surge detection methods using empirical mode decomposition and continuous wavelet transform for a centrifugal compressor

Xin Wu,Yibing Liu,Rui Liu,Li Zhao 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.4

The occurrence of surge in a centrifugal compressor results in large oscillations in pressure and flow. To avoid damaging the compressor because of surge, we develop several surge detection methods in this study. Considering the incipient surge phenomenon, the Empirical mode decomposition (EMD) and the Morlet Continuous wavelet transform (CWT) methods are selected. Both methods are validated through experimental data collected from surge tests conducted on the three-stage Ingersoll-Rand Centac centrifugal compressor at Toyota Motor Manufacturing in Kentucky, USA. For incipient surge detection, the EMD-based method can determine the threshold 1 sec earlier than the Morlet CWT-based method. Therefore, the EMD method can be used to implement the incipient surge detection scheme on the tested centrifugal compressor for safety considerations.

Mast Cells Tryptase Promotes Intestinal Fibrosis in Natural Decellularized Intestinal Scaffolds

Wan Jian,Wu Tianqi,Liu Ying,Yang Muqing,Fichna Jakub,Guo Yibing,Yin Lu,Chen Chunqiu 한국조직공학과 재생의학회 2022 조직공학과 재생의학 Vol.19 No.4

BACKGROUND: Standard two-dimensional (2D) culture has confirmed the mechanism of mast cells (MCs) in the pathogenesis of inflammatory bowel disease (IBD), but the regulation of signaling responses of MCs may well differ in three-dimensional (3D) microenvironments. The aim of the study was to develop a 3D culture model based on decellularized intestinal scaffolds (DIS) and verify how MCs influenced fibroblasts phenotype in the 3D model. METHODS: DIS were achieved using the detergent technique and extracellular matrix (ECM) components were verified by histologic analysis, quantification and scanning electron microscope. After human colon fibroblasts recellularized into the scaffolds and activated by MCs tryptase and TGFb1, the changes in genes and signaling pathways during fibroblasts activation in 3D were studied and compared with the changes in 2D cell culture on plastic plates. RESULTS: Decellularization process effectively removed native cell debris while retaining natural ECM components and structure. The engrafted fibroblasts could penetrate into the scaffolds and maintain its phenotype. No matter whether fibroblasts were cultured in 2D or 3D, MCs tryptase and transforming growth factor b1 (TGF-b1) could promote the differentiation of fibroblasts into fibrotic-phenotype myofibroblasts through Akt and Smad2/3 signaling pathways. Furthermore, the pro-collagen1a1 and fibronectin synthesis of myofibroblasts in 3D was higher than in 2D culture. CONCLUSION: Our results demonstrated that the DIS can be used as a bioactive microenvironment for the study of intestinal fibrosis, providing an innovative platform for future intestinal disease modeling and screening of genes and signaling pathways.

Screening and Identification of ClpE Interaction Proteins in Streptococcus pneumoniae by a Bacterial Two-Hybrid System and Co-immunoprecipitation

WenJuan Yan,YingYing Cai,Qun Zhang,YuSi Liu,WenChun Xu,YiBing Yin,YuJuan He,Hong Wang,XueMei Zhang 한국미생물학회 2013 The journal of microbiology Vol.51 No.4

Hsp100/Clp proteins have crucial functions in the protein quality control, stress tolerance, and virulence of many pathogenic bacteria. ClpE is an important virulence factor involved in adherence and invasion in Streptococcus pneumoniae. To explore the underlying mechanism, we screened ClpE interaction proteins using a bacterial two-hybrid system and co-immunoprecipitation. We used ClpE as bait and constructed the pBT-ClpE bait plasmid for two-hybrid screening. Then, we constructed ClpE::GFP fusion for co-immunoprecipitation screening using anti-GFP monoclonal antibody. We obtained eight potential ClpE interaction proteins,including carbamoyl-phosphate synthase, pyruvate oxidase (SpxB), phosphoenolpyruvate-protein phosphotransferase,aminopeptidase N (pepN), L-lactate dehydrogenase, ribosomal protein S4, sensor histidine kinase (SPD_2019), and FtsW (a cell division protein). FtsW, SpxB, pepN, and SPD_2019 were confirmed to interact with ClpE using Bacterial Two-hybrid or Co-immunoprecipitation. Morphologic observations found that ΔclpE strain existed in abnormal division. β-Galactosidase activity assay suggested that ClpE contributed to the degradation of FtsW. Furthermore, FtsW could be induced by heat shock. The results suggested that ClpE might affect cell division by regulating the level of FtsW. These data may provide new insights in studying the role of ClpE in S. pneumoniae.