Application of Neural Network Based on Real-Time Recursive Learning and Kalman Filter in Flight Data Identification

Yao Li,Haiqing Si,Yitong Zong,Xiaojun Wu,Peihong Zhang,Hongyin Jia,Shuqing Xu,Dayong Tang 한국항공우주학회 2021 International Journal of Aeronautical and Space Sc Vol.22 No.6

The process of obtaining flight data from flight test is complex and costly, which makes it difficult to identify aerodynamic parameters. Therefore, Cessna172 flight simulator was used for flight data extraction, which ensures the convenience, efficiency and economy of the test. To obtain aerodynamic model, based on the idea of machine learning, a recurrent neural network was used to process multi-dimensional nonlinear flight test data, and a real-time recursive learning algorithm was proved to be suitable for dynamic training. Due to the large amount of state parameter data generated by aircraft, which will cause the real-time recursive learning algorithm to train slowly. So, Kalman filter algorithm was introduced for system identification. Considering validity analysis, the comparative verification method was used to verify system identification model. Results show that the aircraft aerodynamic and aerodynamic moment models have good applicability and can be popularized and applied.

Optimization design research of air flow distribution in vertical radial flow adsorbers

Yao Li,Haiqing Si,Bing Wang,Lu Xue,Xiaojun Wu 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.4

Non-uniform flow distribution usually exists in a vertical radial flow adsorber, which significantly decreases the utilization of adsorbents. We adopted numerical simulation methods based on the ANSYS Fluent 15.0 software to study the flow pattern in vertical radial flow adsorber, where programs of user-defined functions (UDF) were set up to interpret component equation, momentum equation and energy equation. To solve the problem of non-uniform air distribution, the relationship between the radial pressure drop across the bed and the ratio of cross-sectional area of the central pipe to that of the annular channel was studied, and optimization design of the distributor inserted in the central channel was given by parametric method at the same time. Through comparative analysis in the given experimental condition, the uniformity reached about 99.1% and the breakthrough time extended from 564 s to 1,175 s under the present optimized design method.

Template-assisted preparation of metal-modified SAPO-34 molecular sieves for the catalysis of methanol-to-olefins

Jihui Yao,Jiapeng Jiao,Ruiqiang Liu,Fei Zha,Xiaojun Guo,Xiaohua Tang,Haifeng Tian,Yue Chang 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.7

To improve the dispersion of metals and to enhance the catalytic performance of SAPO-34 molecular sieves, the template-assisted method was applied to synthesize Co, Ni and Zn modified SAPO-34 molecular sieves by using palygorskite as silicon source and tetraethylammonium hydroxide as template. The metal modified SAPO-34 molecular sieves were characterized by XRD, SEM, XPS, N2-adsorption-desorption, NH3-TPD, FTIR, ICP-AES and TG. The N atoms of tetraethylammonium hydroxide exhibited the different forces to three metal ions, thus the acidity of the molecular sieves was further regulated. Compared with metal modified SAPO-34 molecular sieves prepared by impregnation, metal modified SAPO-34 molecular sieves prepared by template-assisted maintained higher surface area, bigger pore volume and better dispersion of metals. The catalytic performance of metal modified SAPO-34 molecular sieves prepared by template-assisted method in the reaction of methanol-to-olefins (MTO) was investigated in the fixed bed reactor. Under the reaction conditions that the reaction temperature was 400 oC, the reaction pressure was 0.1 MPa, the feed WHSV was 2.0 h1 and the mass of catalyst was 0.5 g, Ni modified SAPO-34 molecular sieves exhibited great methanol conversion and high selectivity to light olefins. The selectivity of light olefins reached 95.7%.

Important Role of Immunological Responses to Environmental Exposure in the Development of Allergic Asthma

Xinliu Lin,Xia Ren,Xiaojun Xiao,Zhaowei Yang,Siyang Yao,Gary WK Wong,Zhigang Liu,Charles Wang,Zhong Su,Jing Li 대한천식알레르기학회 2020 Allergy, Asthma & Immunology Research Vol.12 No.6

Allergic asthma is a public health problem that affects human health and socioeconomic development. Studies have found that the prevalence of asthma has significantly increased in recent years, which has become particularly pronounced in developed countries. With rapid urbanization in China in the last 3 decades, the prevalence of asthma has increased significantly in urban areas. As changes in genetic backgrounds of human populations are limited, environmental exposure may be a major factor that is responsible for the increased prevalence of asthma. This review focuses on environmental components of farms and rural areas that may have protective effects in reducing the development of asthma. Farm and rural related microorganism- and pathogen-associated molecular patterns are considered to be important environmental factors that modulate host's innate and adaptive immune system to induce protection effects later in life. Environmental microbial-related immunotherapy will also be discussed as the future research direction for the prevention of allergic asthma.

Fault-Tolerant Control of Cascaded H-Bridge Converters Using Double Zero-Sequence Voltage Injection and DC Voltage Optimization

Ji, Zhendong,Zhao, Jianfeng,Sun, Yichao,Yao, Xiaojun,Zhu, Zean The Korean Institute of Power Electronics 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.5

Cascaded H-Bridge (CHB) converters can be directly connected to medium-voltage grids without using transformers and they possess the advantages of large capacity and low harmonics. They are significant tools for providing grid connections in large-capacity renewable energy systems. However, the reliability of a grid-connected CHB converter can be seriously influenced by the number of power switching devices that exist in the structure. This paper proposes a fault-tolerant control strategy based on double zero-sequence voltage injection and DC voltage optimization to improve the reliability of star-connected CHB converters after one or more power units have been bypassed. By injecting double zero-sequence voltages into each phase cluster, the DC voltages of the healthy units can be rapidly balanced after the faulty units are bypassed. In addition, optimizing the DC voltage increases the number of faulty units that can be tolerated and improves the reliability of the converter. Simulations and experimental results are shown for a seven-level three-phase CHB converter to validate the efficiency and feasibility of this strategy.

Fault-Tolerant Control of Cascaded H-Bridge Converters Using Double Zero-Sequence Voltage Injection and DC Voltage Optimization

Zhendong Ji,Jianfeng Zhao,Yichao Sun,Xiaojun Yao,Zean Zhu 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.5

Cascaded H-Bridge (CHB) converters can be directly connected to medium-voltage grids without using transformers and they possess the advantages of large capacity and low harmonics. They are significant tools for providing grid connections in large-capacity renewable energy systems. However, the reliability of a grid-connected CHB converter can be seriously influenced by the number of power switching devices that exist in the structure. This paper proposes a fault-tolerant control strategy based on double zero-sequence voltage injection and DC voltage optimization to improve the reliability of star-connected CHB converters after one or more power units have been bypassed. By injecting double zero-sequence voltages into each phase cluster, the DC voltages of the healthy units can be rapidly balanced after the faulty units are bypassed. In addition, optimizing the DC voltage increases the number of faulty units that can be tolerated and improves the reliability of the converter. Simulations and experimental results are shown for a seven-level three-phase CHB converter to validate the efficiency and feasibility of this strategy.

Effects of Xylanase on Performance, Blood Parameters, Intestinal Morphology, Microflora and Digestive Enzyme Activities of Broilers Fed Wheat-based Diets

Luo, Dingyuan,Yang, Fengxia,Yang, Xiaojun,Yao, Junhu,Shi, Baojun,Zhou, Zhenfeng Asian Australasian Association of Animal Productio 2009 Animal Bioscience Vol.22 No.9

The study was conducted to investigate the effects of different levels of xylanase on performance, blood parameters, intestinal morphology, microflora and digestive enzyme activities of broilers. The wheat-based diets were supplemented with 0, 500, 1,000, 5,000 U/kg xylanase. Xylanase supplementation significantly (p<0.05) improved the feed:gain ratio of broilers from 1 to 21 d and 1 to 42 d. Supplementing 500 U/kg and 1,000 U/kg xylanase improved (p<0.05) the villus height and the ratio of villus height to crypt depth in the small intestine. Excess supplementation of xylanase (5,000 U/kg) increased the villus height in the ileum (p<0.01) and the ratio of villus height to crypt depth in the duodenum and ileum (p<0.05). The microflora in the ileum and caecum, digestive enzyme activities in the small intestine and the concentrations of serum glucose, uric acid, insulin and IGF-I were not affected by the supplementation of xylanase. Excess level of xylanase (5,000 U/kg) had a tendency to induce the multiplication of E. coli and total aerobes. The results suggested that supplementing 500 U/kg and 1,000 U/kg xylanase was beneficial for broilers and excess xylanase supplementation resulted in no further improvement or negative effects.