HHT method for system identification and damage detection: an experimental study

Lily L. Zhou,Gang Yan 국제구조공학회 2006 Smart Structures and Systems, An International Jou Vol.2 No.2

Recently, the Hilbert-Huang transform (HHT) has gained considerable attention as a novel technique of signal processing, which shows promise for the system identification and damage detection of structures. This study investigates the effectiveness and accuracy of the HHT method for the system identification and damage detection of structures through a series of experiments. A multi-degree-of-freedom (MDOF) structural model has been constructed with modular members, and the columns of the model can be replaced or removed to simulate damages at different locations with different severities. The measured response data of the structure due to an impulse loading is first decomposed into modal responses using the empirical mode decomposition (EMD) approach with a band-pass filter technique. Then, the Hilbert transform is subsequently applied to each modal response to obtain the instantaneous amplitude and phase angle time histories. A linear least-square fit procedure is used to identify the natural frequencies and damping ratios from the instantaneous amplitude and phase angle for each modal response. When the responses at all degrees of freedom are measured, the mode shape and the physical mass, damping and stiffness matrices of the structure can be determined. Based on a comparison of the stiffness of each story unit prior to and after the damage, the damage locations and severities can be identified. Experimental results demonstrate that the HHT method yields quite accurate results for engineering applications, providing a promising tool for structural health monitoring.

USP15 inhibits multiple myeloma cell apoptosis through activating a feedback loop with the transcription factor NF-κBp65

Lili Zhou,Hua Jiang,Juan Du,Lu Li,Rong Li,Jing Lu,Weijun Fu,Jian Hou 생화학분자생물학회 2018 Experimental and molecular medicine Vol.50 No.-

USP15 has been shown to stabilize transcription factors, to be amplified in many cancers and to mediate cancer cell survival. However, the underlying mechanism by which USP15 regulates multiple myeloma (MM) cell proliferation and apoptosis has not been established. Here, our results showed that USP15 mRNA expression was upregulated in MM patients. USP15 silencing induced MM cell proliferation inhibition, apoptosis, and the expression of nuclear and cytoplasmic NF-κBp65, while USP15 overexpression exhibited an inverse effect. Moreover, in vivo experiments indicated that USP15 silencing inhibited MM tumor growth and NF-κBp65 expression. PDTC treatment significantly inhibited USP15 overexpression-induced cell proliferation, apoptosis inhibition, and NF-κBp65 expression. USP15 overexpression promoted NF-κBp65 expression through inhibition of its ubiquitination, whereas NF-κBp65 promoted USP15 expression as a positive regulator. Taken together, the USP15-NF-κBp65 loop is involved in MM tumorigenesis and may be a potential therapeutic target for MM.

HHT method for system identification and damage detection: an experimental study

Zhou, Lily L.,Yan, Gang Techno-Press 2006 Smart Structures and Systems, An International Jou Vol.2 No.2

Recently, the Hilbert-Huang transform (HHT) has gained considerable attention as a novel technique of signal processing, which shows promise for the system identification and damage detection of structures. This study investigates the effectiveness and accuracy of the HHT method for the system identification and damage detection of structures through a series of experiments. A multi-degree-of-freedom (MDOF) structural model has been constructed with modular members, and the columns of the model can be replaced or removed to simulate damages at different locations with different severities. The measured response data of the structure due to an impulse loading is first decomposed into modal responses using the empirical mode decomposition (EMD) approach with a band-pass filter technique. Then, the Hilbert transform is subsequently applied to each modal response to obtain the instantaneous amplitude and phase angle time histories. A linear least-square fit procedure is used to identify the natural frequencies and damping ratios from the instantaneous amplitude and phase angle for each modal response. When the responses at all degrees of freedom are measured, the mode shape and the physical mass, damping and stiffness matrices of the structure can be determined. Based on a comparison of the stiffness of each story unit prior to and after the damage, the damage locations and severities can be identified. Experimental results demonstrate that the HHT method yields quite accurate results for engineering applications, providing a promising tool for structural health monitoring.

Chlorogenic Acid Decreased Intestinal Permeability and Ameliorated Intestinal Injury in Rats via Amelioration of Mitochondrial Respiratory Chain Dysfunction

Yan Zhou,Zheng Ruan,Lili Zhou,Yuhui Yang,Shumei Mi,Ze-Yuan Deng,Yulong Yin 한국식품과학회 2016 Food Science and Biotechnology Vol.25 No.1

Chlorogenic acid (CGA), an abundant polyphenol compound in plants, exhibits anti-oxidant effects. The protective effect of CGA in the rat intestine with endotoxin infusion was evaluated. CGA administration ameliorated endotoxin-induced intestinal injury, and decreased the ratio of lactulose/ mannitol, the ileum pathological grade, the myeloperoxidase activity in the ileum, and the malondialdehyde content in the ileum and in ileum mitochondria. The small intestine weight, activities of alkaline phosphatase and superoxide dismutase in the ileum, and β-nicotinamide adenine dinucleotide reduce form (NADH) dehydrogenase and succinate dehydrogenase activities in ileum mitochondria were increased. Intestinal permeability was positively correlated with intestinal mitochondrial injury indicated as the level of malondialdehyde in ileum mitochondria, and negatively correlated with NADH dehydrogenase activity. Dietary administration of CGA protected against increased intestinal permeability caused by endotoxin infusion. The protective effect of CGA was probably associated with a decrease in mitochondrial lipid peroxidation levels and an increase in NADH dehydrogenase activity.

Isovitexin Protects Mice from Methicillin- Resistant Staphylococcus aureus-Induced Pneumonia by Targeting Sortase A

( Lili Tian ),( Xinliang Wu ),( Hangqian Yu ),( Fengying Yang ),( Jian Sun ),( Tiezhong Zhou ),( Hong Jiang ) 한국미생물생명공학회 2022 Journal of microbiology and biotechnology Vol.32 No.10

The rise of methicillin-resistant Staphylococcus aureus (MRSA) has resulted in significant morbidity and mortality, and clinical treatment of MRSA infections has become extremely difficult. Sortase A (SrtA), a virulence determinant that anchors numerous virulence-related proteins to the cell wall, is a prime druggable target against S. aureus infection due to its crucial role in the pathogenicity of S. aureus. Here, we demonstrate that isovitexin, an active ingredient derived from a variety of traditional Chinese medicines, can reversibly inhibit SrtA activity in vitro with a low dose (IC₅₀=24.72 μg/ml). Fluorescence quenching and molecular simulations proved the interaction between isovitexin and SrtA. Subsequent point mutation experiments further confirmed that the critical amino acid positions for SrtA binding to isovitexin were Ala-92, Ile-182, and Trp-197. In addition, isovitexin treatment dramatically reduced S. aureus invasion of A549 cells. This study shows that treatment with isovitexin could alleviate pathological injury and prolong the life span of mice in an S. aureus pneumonia model. According to our research, isovitexin represents a promising lead molecule for the creation of anti-S. aureus medicines or adjuncts.

A fast and powerful aggregated Cauchy association test for joint analysis of multiple phenotypes

Lili Chen,Yajing Zhou 한국유전학회 2021 Genes & Genomics Vol.43 No.1

Background Pleiotropy is a widespread phenomenon in complex human diseases. Jointly analyzing multiple phenotypes can improve power performance of detecting genetic variants and uncover the underlying genetic mechanism. Objective This study aims to detect the association between genetic variants in a genomic region and multiple phenotypes. Methods We develop the aggregated Cauchy association test to detect the association between rare variants in a genomic region and multiple phenotypes (abbreviated as “Multi-ACAT”). Multi-ACAT frst detects the association between each rare variant and multiple phenotypes based on reverse regression and obtains variant-level p-values, then takes linear combination of transformed p-values as the test statistic which approximately follows Cauchy distribution under the null hypothesis. Results Extensive simulation studies show that when the proportion of causal variants in a genomic region is extremely small, Multi-ACAT is more powerful than the other several methods and is robust to bi-directional efects of causal variants. Finally, we illustrate our proposed method by analyzing two phenotypes [systolic blood pressure (SBP) and diastolic blood pressure (DBP)] from Genetic Analysis Workshop 19 (GAW19). Conclusion The Multi-ACAT computes extremely fast, does not consider complex distributions of multiple correlated phenotypes, and can be applied to the case with noise phenotypes.

Study of the Effectiveness of the RVEs for Random Short Fiber Reinforced Elastomer Composites

Lili Chen,Boqin Gu,Jianfeng Zhou,Jiahui Tao 한국섬유공학회 2019 Fibers and polymers Vol.20 No.7

The effectiveness of the representative volume elements (RVEs) established by a modified random sequentialadsorption method for random short fiber reinforced elastomer composites (SFECs) was studied. The RVE is considered tobe effective when the RVE’s fiber orientation is isotropic. And the effectiveness of the RVEs was verified by evaluating themechanical properties in different loading directions based on the finite element method. The results show that the fibernumber N=4000 can be regarded as a steady threshold for the isotropy of the fiber orientation in RVEs with various fiberaspect ratios and dilute volume fraction.

Distortional Buckling Analysis of I-Steel Concrete Composite Beams Subjected to Hogging Moment

Lili Liu,Lizhong Jiang,Chun-dan Li,Wang-Bao Zhou,Lei-xin Nie 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.3

Bending-torsional distortion buckling is one of the most critical buckling modes of steel–concrete composite beams when they are working under hogging moment. The rotational and lateral restraint stiff ness provided by the steel web to the steel bottom fl ange are the key factors to determine this form of buckling. Firstly, the formula for solving the elastic rotational restraint stiff ness of the composite fl ange of steel beam upper fl ange and concrete slab to the steel web is derived. Then, the equivalent lateral and rotational restraint stiff ness of the steel bottom fl ange subjected to hogging moment are thoroughly studied. Considering the rotation restraint eff ect of the composite fl ange, this paper provides the calculation formula for the critical bending moment of I-steel concrete composite beams (I-SCCB) under hogging moment. Fifteen examples are considered to calculate the critical bending moment of the I-SCCB under hogging moment with the simplifi ed analytical method introduced in this paper. The results are compared with the ones derived by ANSYS numerical analyses and relevant research of other scholars. The infl uence of the arrangement of the shear studs on the critical bending moment of the I-SCCB is investigated. It is concluded that the results given by the simplifi ed analytical method are in good agreement with the ones obtained by the ANSYS fi nite element numerical method. Both methods show that the critical load of the distortional buckling of the I-SCCB under hogging moment is less aff ected by the member’s length. The critical bending moment of distortional buckling of the I-SCCB signifi cantly increases with the presence of shear studs. However, once shear studs are used, it tends to be stable with the increase of equivalent restrained torsional rotational stiff ness at the top edge of the steel web.

Microstructure and property evolution of diamond-like carbon films co-doped by Al and Ti with different ratios

Zhou, Yong,Guo, Peng,Sun, Lili,Liu, Linlin,Xu, Xiaowei,Li, Wenxian,Li, Xiaowei,Lee, Kwang-Ryeol,Wang, Aiying Elsevier Sequoia 2019 Surface & coatings technology Vol.361 No.-

<P><B>Abstract</B></P> <P>Diamond-like carbon (DLC) films with weak carbide metal Al and carbide metal Ti co-doping (Al/Ti-DLC) were prepared by a hybrid ion beam deposition system. The atomic ratios of doped Al to Ti were tailored via designing the special Al/Ti combined sputtering target. The composition, microstructure, roughness, residual stress, hardness, toughness, and tribological behaviors of the deposited films were systematically evaluated to explore the dependence of structural properties on Al/Ti ratios. Results indicated that the high-throughput preparation of DLC films with different Al/Ti atomic ratios was achieved by tailoring the sputtering target and process parameters without the difference in both the film thickness and total Al/Ti content. With the Al/Ti ratios in the films decreased from 8.8 to 3.0, the residual stress, hardness, and toughness of Al/Ti-DLC films increased obviously, originating from the increased fraction of titanium carbide and the reduced Al content. However, the coefficient of friction and wear rate with decreasing the Al/Ti ratio were obviously improved, which was related with the transformation of underlying friction mechanism from the sliding interface graphitization to dangling bond-passivation. The present results not only suggest a high-throughput method to fabricate co-doped DLC films, but also promote the scientific understanding and engineering application of DLC films with high performance.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ti/Al co-doped diamond-like carbon films were fabricated by a hybrid ion beam method. </LI> <LI> Different Al/Ti ratios were successfully achieved at one time using designed target. </LI> <LI> Al/Ti ratios had no effect on the chemical state of co-doped Ti and Al atoms. </LI> <LI> The mechanical and tribological properties were strongly dependent on Ti/Al ratios. </LI> <LI> Different friction mechanisms were observed with Al/Ti ratios ranged from 8.8 to 3.0. </LI> </UL> </P>

Preparation and Properties of Functional Fabric Coating Based on SiO2-aerogel/Polyurethane

Lili Xu,Yan Liu,Binjie Xin,Yuanyuan Zhou 한국섬유공학회 2022 Fibers and polymers Vol.23 No.7

The silane coupling agent modified SiO2 particles, multi aperture silica aerogel and waterborne polyurethaneacrylate (WPUA) were blended to produce resin coated fabrics with good thermal stability, to achieve excellent waterrepellency and a certain protective property. The thermal stability and water repellency of ordinary cotton could be improvedby the hydrophobic SiO2 particles, WPUA and silica aerogel (SA) powders on the fabric surface. Our experimental resultsillustrated that the thermal stability of the coated fabric was greatly improved by adding aerogels and silane modified SiO2,and the amount of residual carbon increased significantly at 600 °C as the corresponding residues of SA/WPUA coated fabricfinally could be 13.19 %. The water contact angle of the fabric was obviously increased after the silane modified SiO2particles mixed with SA/WPUA. It was found that the more aerogel added, the larger the contact angle was, and the contactangel reached about 120 ° when the aerogel was 4 wt%. It could be proved that the coated fabric had a certain surface selfcleaningeffect. The tensile tests characterized that the stress of the coated fabric reached the maximum value of 64 MPawhen the aerogel dosage was 2 wt%. Chemical resistance analysis suggested that the fabric had similar chemical resistanceafter the integration of porous aerogel particles. However, unlike most polyurethane coatings, the majority of chemicals wereadsorbed in aerogel coatings. The infrared spectrum of the coating samples showed that the coating surface was stable, whichwas attributed to the interfacial adhesion between cotton fiber and polyurethane adhesive. The appearance of aerogel andSiO2 particles dispersed on the fabric surface was analyzed by SEM. All outcomes indicated a significant improvement ingeneral properties of WPUA coatings by adding a handful of silica aerogel (0.5-4 wt %).