Hierarchical Parameter Estimation for the Frequency Response Based on the Dynamical Window Data

Ling Xu,Weili Xiong,Ahmed Alsaedi,Tasawar Hayat 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.4

This paper studies the problem of parameter estimation for frequency response signals. For a linear system, the frequency response is a sine signal with the same frequency as the input sine signal. When a multifrequency sine signal is applied to a system, the system response also is a multi-frequency sine signal. The signal modeling for multi-frequency sine signals is very difficult due to the highly nonlinear relations between the characteristic parameters and the model output. In order to obtain the parameter estimates of the multi-frequency sine signal, the signal modeling methods based on statistical identification are proposed by means of the dynamical window discrete measured data. By constructing a criterion function with respect to the model parameters to be estimated, a hierarchical multi-innovation stochastic gradient estimation method is derived through parameter decomposition. Moreover, the forgetting factor and the convergence factor are introduced to improve the performance of the algorithm. The simulation results show the effectiveness of the proposed methods.

Synthesis and Electrochemical Properties of LiV3O8/PAn Composite as a Cathode Material for Lithium Secondary Batteries

Ling-Ling Xie,Xiao-Yu Cao,Li-Xu Zhang,Zhong-Xu Dai,Ling-Bo Qu 대한금속·재료학회 2013 ELECTRONIC MATERIALS LETTERS Vol.9 No.2

A LiV3O8/polyaniline (PAn) composite was prepared by the in-situ polymerization method assisted by sodium dodecyl sulfate and ammonium persulfate. The as-prepared powders were investigated by XRD, SEM, and galvanostatic discharge/charge analysis. It was found that the introduction of PAn to LiV3O8 can effectively buffer the mechanical stress and restrain the number of phase changes of composite material during the electrochemical cycling. Compared with pristine LiV3O8, LiV3O8/PAn composite maintains a reversible capacity of 212.1 mAh g−1 at the current density of 30 mA g−1 after 50 cycles, approximately 22.6%, much higher than the former.

Elastic Foundation Beam Solution of Tensile Flexible Retaining Wall

Xu Jianqiang,Xu Jiangbo,Yang Xiaohua,Yan Zhaobai,Li Haiping,Wang Huoming,Tan Ling,Fei Dongyang,Li Jianguo,Luo Yongzhen 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.2

The application of fl exible retaining walls in foundation pit engineering is gradually increasing. At present, many practical engineering problems need to be solved. This article takes a corrugated steel retaining wall with tensile reinforcement, for example, assuming that it is an elastic foundation beam model. A typical vertical thin layer unit is taken on the retaining wall for analysis. It uses the waveform integration method to calculate the moment of inertia, deriving the diff erential equation of fl exural deformation of corrugated steel retaining wall and establishing the theoretical formula for deformation of corrugated steel retaining wall under fi lling pressure behind the wall. Finally, a FLAC3D model was established to simulate the deformation of corrugated steel retaining walls in practical engineering, and the fi nal numerical simulation results were consistent with the theoretical formula. Thus, providing a theoretical basis for the deformation of such fl exible retaining structures.

Nonlinear Analysis of Single Reinforced Concrete Piles Subjected to Lateral Loading

Ling-Yu Xu,Fei Ca,Guo-Xin Wang,Guo-Xing Chen,Yong-Yi Li 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.7

This paper proposes a method for the nonlinear analysis of laterally loaded single reinforced concrete piles based on the beam-onnonlinear- Winkler-foundation approach. A nonlinear fiber beam-column element is used to model the nonlinear behavior of a pile. The pile is divided into a series of segments, of which the cross section is assumed to be plane and normal to the longitudinal axis. The internal force of a segment is derived by integrating the nonlinear stress-strain relationships of all steel and concrete fibers within the cross section of the segment. The substructure technique is introduced to calculate the stiffness matrix of the segments. The nonlinear behavior of soils surrounding the pile is characterized by a modified strain wedge model. The results show that (1) the predicted results using the proposed method are consistent with the measurements for all three full-scale tested piles, and (2) updating the neutral axis of segments has a significant effect on the calculated lateral deflection; however, it has a slight effect on the calculated bending moment. Moreover, an empirical equation is derived from the numerical analyses for estimating the cracked flexural rigidity of bored piles subjected to lateral loading.

Mortality Characteristic and Prediction of Nasopharyngeal Carcinoma in China from 1991 to 2013

Xu, Zhen-Xi,Lin, Zhi-Xiong,Fang, Jia-Ying,Wu, Ku-Sheng,Du, Pei-Ling,Zeng, Yang,Tang, Wen-Rui,Xu, Xiao-Ling,Lin, Kun Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.15

Background: To analyze the mortality distribution of nasopharyngeal carcinoma in China from 1991 to 2013, to predict the mortality in the ensuing five years, and to provide evidence for prevention and treatment of nasopharyngeal carcinoma. Materials and Methods: Mortality data for Nasopharyngeal Carcinoma in China from 1991 to 2013 were used to describe its epidemiological characteristics, such as the change of the standardized mortality rate, sex and age differences, urban-rural differences. Trend-surface analysis was used to study the geographical distribution of the mortality. Curve estimation, time series, gray modeling, and joinpoint regression were used to predict the mortality for the ensuing five years in the future. Results: In China, the standardized mortality rate of Nasopharyngeal Carcinoma increased with time from 1996, reaching the peak values of $1.45/10^5$ at the year of 2002, and decreased gradually afterwards. With males being 1.51 times higher than females, and the city had a higher rate than the rural during the past two decades. The mortality rate increased from age 40. Geographical analysis showed the mortality rate increased from middle to southern China. Conclusions: The standardized mortality rate of Nasopharyngeal Carcinoma is falling. The regional disease control for Nasopharyngeal Carcinoma should be focused on Guangdong province of China, and the key targets for prevention and treatment are rural men, especially after the age of 40. The mortality of Nasopharyngeal Carcinoma will decrease in the next five years.

Intake of Korean Red Ginseng Extract and Saponin Enhances the Protection Conferred by Vaccination with Inactivated Influenza A Virus

Xu, Mei Ling,Kim, Hyoung-Jin,Choi, Yoo-Ri,Kim, Hong-Jin The Korean Society of Ginseng 2012 Journal of Ginseng Research Vol.36 No.4

Vaccination is the main strategy for preventing influenza infection. However, vaccine efficacy is influenced by several factors, including age and health status. The efficacy of the influenza vaccine is much lower (17% to 53%) in individuals over 65 yr of age compared with young adults (70% to 90%). Therefore, increasing vaccine efficacy remains a challenge for the influenza vaccine field. In this study, we investigated the impact of supplementing vaccination with the dietary intake of Korean red ginseng (RG) extract and RG saponin. Mice were immunized two times intranasally with inactivated influenza A (H1N1) virus. Mice received RG extract or RG saponin orally for 14 d prior to the primary immunization. After the primary immunization, mice continued to receive RG extract or RG saponin until the secondary immunization. Mice vaccinated in combination with dietary intake of RG extract and RG saponin showed elevated serum anti-influenza A virus IgG titers and improved survival rates in lethal influenza A virus infection: 56% and 63% of mice receiving RG extract or RG saponin survived, respectively, while 38% of mice that only received the vaccine survived. Moreover, mice receiving RG extract supplementation recovered their body weight more quickly than those not receiving RG extract supplementation. We propose that the dietary intake of RG extract and RG saponin enhances the vaccine-induced immune response and aids in providing protection against influenza virus infection.

Two-step chromatographic purification of glutathione S-transferase-tagged human papillomavirus type 16 E6 protein and its application for serology

Xu, Mei Ling,Kim, Seung Cheol,Kim, Hyoung Jin,Ju, Woong,Kim, Yun Hwan,Kim, Hong-Jin Elsevier 2017 Protein expression and purification Vol.132 No.-

<P><B>Abstract</B></P> <P>Human papillomavirus (HPV) E6 protein is an oncoprotein with a pivotal role in cervical carcinogenesis. Expression and purification of HPV E6 from <I>Escherichia coli</I> (<I>E. coli</I>) has been difficult because of its strong hydrophobicity even when expressed as a fusion protein with glutathione S-transferase (GST). There has been no protocol suggested for purifying GST-tagged HPV E6 protein with high purity so far. Herein, we provide efficient protocol for purifying GST-HPV16 E6 protein for the first time. In the current study, the GST-tagged protein was expressed in <I>E. coli</I> and a purification method was designed using cation-exchange chromatography followed by GST-affinity chromatography. Using physiological pH buffer during cell lysis and first cation-exchange chromatography significantly reduced yield of full-length GST-HPV16 E6 protein. It was found that using an alkaline buffer during cation-exchange chromatography was needed to obtain full length GST-HPV16 E6 protein. GST-HPV16 E6 protein recovered from the purification using alkaline condition retained its inherent p53-binding ability. Moreover, we were able to detect anti-HPV16 E6 antibodies with high sensitivity in sera from patients with cervical cancer using the GST–HPV16 E6 protein. It was found that the GST-HPV16 E6 protein could be used as a coating agent to enhance the sensitivity of detection of serum anti-HPV16 E6 antibodies when treated with ethylene glycol-bis (β-aminoethyl ether)-N,N,N′,N'-tetraacetic acid (EGTA). These results indicate that the two-step chromatographic purification allows obtaining high purity of GST-HPV16 E6 protein and the GST-HPV16 E6 is suitable to be used as an antigen of serology assay.</P> <P><B>Highlights</B></P> <P> <UL> <LI> High purity of GST-HPV16 E6 was successfully purified under alkaline condition. </LI> <LI> GST-HPV16 E6 purified under alkaline condition has ability for p53 binding. </LI> <LI> EGTA treatment to GST-HPV16 E6 increases reactivity towards anti-HPV16 E6 antibody. </LI> </UL> </P>

Microwave-Assisted Synthesis of Flower-like and Plate-like CuO Nanopowder and Their Photocatalytic Activity for Polluted Lake Water

Ling Xu,Hai-Yan Xu,Feng Wang,Feng-Jun Zhang,Ze-Da Meng,Wei Zhao,오원춘 한국세라믹학회 2012 한국세라믹학회지 Vol.49 No.2

Flower-like and plate-like CuO nanopowder has been successfully synthesized using a facile microwave-assisted synthetic route. The morphology and size of the final products strongly depended on microwave power. The phase, structures and morphologies of the as-prepared products were investigated in detail by BET surface area analysis, X-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM). In addition, the chemical oxygen demand of polluted lake water was employed for characterization of these new photocatalysts. The results showed correlations between the morphology of CuO micro-crystals and their catalytic properties.

Parameter Estimation for Nonlinear Functions Related to System Responses

Ling Xu 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.6

This paper considers the parameter estimation problem of nonlinear models, which are related to the impulse or step response functions of linear time-invariant (LTI) dynamical systems, based on the response data. In terms of the nonlinear characteristic of the models, the nonlinear dynamical optimization scheme is adopted for obtaining the system parameter estimates. By constructing a gradient criterion function, a gradient recursion algorithm is derived. In order to overcome the difficulty of determining the step-size in the gradient recursion algorithm, a trying method and a numerical approach are proposed to achieve the step-size. On this basis, a stochastic gradient estimation method is presented by using a recursive step-size. Furthermore, a multi-innovation stochastic gradient method is deduced for enhancing the estimation accuracy by using the dynamical window data. Finally, a dynamical length stochastic gradient estimation technique is offered to obtain more accurate parameter estimates by using dynamical length measured data from the step response. The examples are provided to examine the algorithm performance and the simulation results indicate that the presented approaches are effective.

Effects of Multiple-target Anti-microRNA Antisense Oligodeoxyribonucleotides on Proliferation and Migration of Gastric Cancer Cells

Xu, Ling,Dai, Wei-Qi,Xu, Xuan-Fu,Wang, Fan,He, Lei,Guo, Chuan-Yong Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.7

Backgrounds: To investigate the inhibiting effects of multi-target anti-microRNA antisense oligonucleotide (MTg-AMOs) on proliferation and migration of human gastric cancer cells. Methods: Single anti-microRNA antisense oligonucleotides (AMOs) and MTg-AMOs for miR-221, 21, and 106a were designed and transfected into SGC7901, a gastric cancer cell line, to target the activity of these miRNAs. Their expression was analyzed using stem-loop RT-PCR and effects of MTg-AMOs on human gastric cancer cells were determined using the following two assay methods: CCK8 for cell proliferation and transwells for migration. Results: In the CCK-8 cell proliferation assay, $0.6{\mu}mol/L$ was selected as the preferred concentration of MTg-AMOs and incubation time was 72 hours. Under these experimental conditions, MTg-AMOs demonstrated better suppression of the expression of miR-221, miR-106a, miR-21 in gastric cancer cells than that of single AMOs (P = 0.014, 0.024; 0.038, respectively). Migration activity was also clearly decreased as compared to those in randomized and blank control groups ($28{\pm}4$ Vs $54{\pm}3$, P <0.01; $28{\pm}4$ Vs $59{\pm}4$, P < 0.01). Conclusions: MTg-AMOs can specifically inhibit the expression of multiple miRNAs, and effectively antagonize proliferation and migration of gastric cancer cells promoted by oncomirs.