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Optimized and coordinated model predictive control scheme for DFIGs with DC-based converter system

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Journal of Modern Power Systems and Clean Energy 2017年第4期5卷 620-630页

作者： shaomin yan Aimin ZHANG Hang ZHANG Jianhua WANG Bin CAI School of Electrical Engineering Xi’an Jiaotong UniversityXi’anChina School of Electronic and Information Engineering Xi’an Jiaotong UniversityXi’anChina School of Engineering Qufu Normal UniversityRizhaoChina

This paper proposes an optimized and coordinated model predictive control(MPC) scheme for doublyfed induction generators(DFIGs) with DC-based converter system to improve the efficiency and dynamic performance in DC grids. In this configuration, the stator and rotor of the DFIG are connected to the DC bus via voltage source converters, namely, a rotor side converter(RSC) and a stator side converter(SSC). Optimized trajectories for rotorflux and stator current are proposed to minimize Joule losses of the DFIG, which is particularly advantageous at low and moderate torque. The coordinated MPC scheme is applied to overcome the weaknesses of the field-oriented control technique in the rotor flux-oriented frame, which makes the rotor flux stable and the stator current track its reference closely and quickly. Lastly, simulations and experiments are carried out to validate the feasibility of the control scheme and to analyze the steady-state and dynamic performance of the DFIG.

关键词： Coordinated model predictive control(MPC)scheme Doubly-fed induction generator(DFIG) DC-based converter system Optimized trajectories Rotor side converter(RSC) Stator side converter(SSC)

Possible Impact of Global Warming on the Evolution of Hemagglutinins from Influenza A Viruses

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Biomedical and Environmental Sciences 2011年第1期24卷 62-67页

作者： yan shaomin WU Guang National Engineering Research Center for Non-food Biorefinery Guangxi Academy of Sciences Nanning 530007 Guangxi China Computational Mutation Project DreamSciTech Consulting Shenzhen 518054 Guangdong China

Objective To determine if global warming has an impact on the evolution of hemagglutinins from influenza A viruses, because both global warming and influenza pandemics/epidemics threaten the world. Methods 4 706 hemagglutinins from influenza A viruses sampled from 1956 to 2009 were converted to a time‐series to show their evolutionary process and compared with the global, northern hemisphere and southern hemisphere temperatures, to determine if their trends run in similar or opposite directions. Point‐to‐point comparisons between temperature and quantified hemagglutinins were performed for all species and for the major prevailing species. Results The comparisons show that the trends for both hemagglutinin evolution and temperature change run in a similar direction. Conclusion Global warming has a consistent and progressive impact on the hemagglutinin evolution of influenza A viruses.

关键词： Evolution Global warming Hemagglutinin Influenza A virus Mutation

Uptake of Polycyclic Aromatic Hydrocarbons across Bacterial Membrane

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Advances in Microbiology 2020年第7期10卷 331-348页

作者： shaomin yan Guang Wu State Key Laboratory of Non-Food Biomass and Enzyme Technology National Engineering Research Center for Non-Food Biorefinery Guangxi Key Laboratory of Biorefinery Guangxi Academy of Sciences Nanning China

Polycyclic aromatic hydrocarbons (PAHs) are important pollutants, whose biodegradation and bioremediation with microorganisms are the promising ways to clean environments and reduce their exposure to humans. Although the transportation of PAHs across bacterial membrane is the first step forwards their biodegradation, it receives less attention. In this mini-review, we explore which transport system for uptake of carbon sources can serve for uptake of PAHs in bacteria, and try to uncover some patterns in their transport mechanisms. Collectively, 1) the major carbohydrate transport system, PTS, is unlikely to take PAHs because PAHs lack a hydroxy group for phosphorylation but aromatic acids are good candidates;2) PAHs could probably go through H+ symporters, especially the low-molecular-weight PAHs, which are partially dissolvable in water;3) it is unlikely that PAHs can produce chemiosmotic ion gradients to go through uniporters;and 4) antiporters could serve as transporters to transport PAHs across bacterial membrane only after the metabolism of PAHs generates extra H+ inside cell. Accordingly, the basic mechanism for uptake of PAHs is whether they can donate H+ in order to generate an electrochemical proton gradient to go through symporters.

关键词： Bacteria Polycyclic Aromatic Hydrocarbon Transport Mechanisms

Prediction of Mutations in H7 Hemagglutinins from Influenza A Virus

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Journal of Biomedical Science and Engineering 2020年第8期13卷 175-186页

作者： shaomin yan Guang Wu National Engineering Research Center for Non-Food Biorefinery State Key Laboratory of Non-Food Biomass and Enzyme Technology Guangxi Biomass Engineering Technology Research Center Guangxi Key Laboratory of Bio-Refinery Nanning China

Influenza A viruses have led several pandemics and epidemics in human history. H7 subtype influenza mainly infects avian but also humans occasionally. Since the outbreak of H7N9 subtype influenza occurred in China in 2013, this virus is still circulating in domestic poultry and leading several waves of influenza. To prevent influenza, vaccination is an important strategy. However, influenza virus evolves constantly, but unpredictably. If we would have a one-to-one cause-mutation relationship, the mutation prediction would be possible. However, many external causes, which led to the mutations in the past, might not leave any trace due to the change in environments, whereas the current virus might not be subject to the historically external causes because of evolution. Furthermore, the protein should have the internal causes, which might be quite unclear and difficult to quantify, to engineer mutations. Indeed, various forces twist proteins into 3-demensional structures, whereas any perturbation could lead to a mutation. Of various internal causes for mutation, randomness in protein primary structure should play an important role in mutation. Over years, we have developed three methods to quantify the randomness within a protein primary structure;thus we build a relationship between cause, which is randomness in primary structure, and mutations, which are occurrence and non-occurrence of mutation. In this way, the cause-mutation relationship becomes the problem of classification, which can be solved using logistic regression and neural network. In this study, we apply this model to predict 1) the mutation positions in H7 hemagglutinins from influenza A virus and 2) the would-be-mutated amino-acids at predicted positions with the amino-acid mutating probability. The results show suitability and predictability in such modelling, and pave the way for further development.

关键词： Hemagglutinin Influenza Mutation Neural Network Prediction Randomness

2-Dimensional HP Foldings of Dermaseptin-J2

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Engineering（科研） 2013年第10期5卷 78-84页

作者： shaomin yan Guang Wu State Key Laboratory of Non-Food Biomass Enzyme Technology National Engineering Research Center for Non-Food Biorefinery Guangxi Key Laboratory of Biorefinery Guangxi Academy of Sciences Nanning China

Although the hydrophobic-polar (HP) model is a simple model to study protein folding, it is an approximation to the real-life case. Dermaseptin is a subfamily of frog skin active peptide family, which has various antimicrobial activities, and dermaseptin-J2 is a newly found peptide composed of 26 amino acids. In this study, the 2-dimensional HP model was used to analyze the foldings of dermaseptin-J2 and its nine mutants, which were converted to different HP sequences according to the normalized amino acid hydrophobicity index with respect to pH levels and the conversion of glycine as hydrophobic or polar, and each has 847,288,609,443 possible foldings. The results show that the foldings with minimal energy have different native states, which are chiral and can be numerically distinguished and ranked according to the normalized amino acid hydrophobicity index. The nine mutants of dermaseptin-J2 do not affect the minimal energy but affect their native states at pH 7. The results demonstrate that two pH levels and conversion of glycine as hydrophobic or polar affect the native state and minimal energy, suggesting these are two ways to modify dermaseptin-J2.

关键词： Dermaseptin Folding Configuration HP Model Hydrophobicity Index Minimal Energy Native State

Correlating Combined Features of Amino Acid and Protein with Crystallization Propensity of Proteins from <i>Mycobacterium tuberculosis</i>

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Journal of Biomedical Science and Engineering 2019年第9期12卷 427-442页

作者： shaomin yan Guang Wu National Engineering Research Center for Non-Food Biorefinery State Key Laboratory of Non-Food Biomass and Enzyme Technology Guangxi Key Laboratory of Bio-Refinery Guangxi Biomass Engineering Technology Research Center Guangxi Academy of Sciences Nanning China

Since a decade ago, both protein and amino acid features have been correlated with crystallization propensity of proteins in order to develop methods to predict whether a protein can be crystallized. In this continuing study, each of three features combining features of amino acid and protein, was correlated with the crystallization propensity of proteins from Mycobacterium tuberculosis using logistic and neural network models. The results showed that two combined features, amino acid distribution probability and future composition, had good predictions on whether a protein would be crystallized in comparison with the predictions obtained from each of 531 amino acid features. The results obtained from the third combined feature, amino acid pair predictability, demonstrated the trend of crystallization propensity in proteins from Mycobacterium tuberculosis.

关键词： Protein Feature Mycobacterium tuberculosis Protein Crystallization

Fitting of precipitation in 49 European capitals from 1901 to 1998 using random walk

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Natural Science 2011年第6期3卷 430-435页

作者： shaomin yan Guang Wu DreamSciTech Consulting Shenzhen Guangdong China

Mathematical modeling of precipitation is an important step to understand the precipitation patterns, and paves the way to possibly predict the precipitation. In this study, we attempt to use the random walk model to fit the annual precipitation in 49 European capitals from 1901 to 1998. At first, we used the simplest random walk model to fit the precipitation walk, which is the conversion of recorded precipitations into ±1 format, and then we used a more complex random walk model to fit the recorded precipi-tations. The results show that the random walk models can fit both precipitation walk and re-corded precipitation. Thus this study provides a model to describe the precipitation patterns during this period in these cities.

关键词： European Capital Fitting Precipitation Random Walk

Elaboration of Simplest Folding Structures in 2-Dimensional Lattice with Delta-Hemolysin and Its Variants in HP Model

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Journal of Biomedical Science and Engineering 2019年第5期12卷 293-309页

作者： shaomin yan Guang Wu State Key Laboratory of Non-food Biomass Enzyme Technology National Engineering Research Center for Non-Food Biorefinery Guangxi Key Laboratory of Biorefinery Guangxi Academy of Sciences Nanning China

Although the advanced 3-dimensional structure measurements provide more and more detailed structures in Protein Data Bank, the simplest 2-dimensional lattice model still looks meaningful because 2-dimensional structures play a complementary role with respect to 3-dimensional structures. In this study, the folding structures of delta-hemolysin and its six variants were studied at 2-dimensional lattice, and their amino acid contacts in folding structures were considered according to HP model with the aid of normalized amino acid hydrophobicity index. The results showed that: 1) either delta-hemolysin or each of its variants could find any of its folding structure in one eighth of 1,129,718,145,924 folding structures because of symmetry, which reduces the time required for folding, 2) the impact of pH on folding structures is varying and associated directly with the amino acid sequence itself, 3) the changes in folding structures of variants appeared different case by case, and 4) the assigning of hydrophobicity index to each amino acid was a way to distinguish folding structures at the same native state. This study can help to understand the structure of delta-hemolysin, and such an analysis can shed lights on NP-problem listed in millennium prize because the HP folding in lattice belongs to a sub-problem of NP-problem.

关键词： Folding Structure Delta-Hemolysin HP Model Hydrophobicity Index Lattice Minimal Energy Native State

Predicting pH Optimum for Activity of Beta-Glucosidases

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Journal of Biomedical Science and Engineering 2019年第7期12卷 354-367页

作者： shaomin yan Guang Wu State Key Laboratory of Non-Food Biomass and Enzyme Technology Guangxi Key Laboratory of Bio-Refinery National Engineering Research Center for Non-Food Biorefinery Guangxi Biomass Engineering Technology Research Center Guangxi Academy of Sciences Nanning China

The working conditions for enzymatic reaction are elegant, but not many optimal conditions are documented in literatures. For newly mutated and newly found enzymes, the optimal working conditions can only be extrapolated from our previous experience. Therefore a question raised here is whether we can use the knowledge on enzyme structure to predict the optimal working conditions. Although working conditions for enzymes can be easily measured in experiments, the predictions of working conditions for enzymes are still important because they can minimize the experimental cost and time. In this study, we develop a 20-1 feedforward backpropagation neural network with information on amino acid sequence to predict the pH optimum for the activity of beta-glucosidase, because this enzyme has drawn much attention for its role in bio-fuel industries. Among 25 features of amino acids being screened, the results show that 11 features can be used as predictors in this model and the amino-acid distribution probability is the best in predicting the pH optimum for the activity of beta-glucosidases. Our study paves the way for predicting the optimal working conditions of enzymes based on the amino-acid features.

关键词： Beta-Glucosidase Enzyme pH Optimum Prediction