Frequency shift of a nanomechanical sensor carrying a nanoparticle using nonlocal Timoshenko beam theory

Zhi-Bin Shen,Dao-Kui Li,Dong Li 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.5

"The frequency shift of a nanomechanical sensor carrying a nanoparticle is studied. A bridged single-walled carbon nanotube (SWCNT)carrying a nanoparticle is modeled as a clamped micro-beam with a concentrated micro-mass at any position. Based on the nonlocal Timoshenko theory of beams, which incorporates size effects into the classical theory, the natural frequencies of the nanomechanical sensor are derived using the transfer function method. The effects of the mass and position of the nanoparticle on the frequency shift are discussed. In the absence of the nonlocal effect, the frequencies are reduced to the results of the classical model, in agreement with those using the finite element method. The obtained results show that when the mass of the attached nanoparticle increases or its location is close to the beam center, the natural frequency decreases, but the shift in frequency increases. The effect of the nonlocal parameter on the frequency shift is significant. Decreasing the length-to-diameter ratio also increases the frequency shift. The natural frequencies and shifts are strongly affected by rotary inertia, and the nonlocal Timoshenko beam model is more adequate than the nonlocal Euler-Bernoulli beam model for short nanomechanical sensors. The obtained results are helpful in the design of SWCNT-based resonator as nanomechanical mass sensor."

Bayesian forecasting approach for structure response prediction and load effect separation of a revolving auditorium

Zhi Ma,Chung-Bang Yun,Yan-Bin Shen,Feng Yu,Hua-Ping Wan,Yao-Zhi Luo 국제구조공학회 2019 Smart Structures and Systems, An International Jou Vol.24 No.4

A Bayesian dynamic linear model (BDLM) is presented for a data-driven analysis for response prediction and load effect separation of a revolving auditorium structure, where the main loads are self-weight and dead loads, temperature load, and audience load. Analyses are carried out based on the long-term monitoring data for static strains on several key members of the structure. Three improvements are introduced to the ordinary regression BDLM, which are a classificatory regression term to address the temporary audience load effect, improved inference for the variance of observation noise to be updated continuously, and component discount factors for effective load effect separation. The effects of those improvements are evaluated regarding the root mean square errors, standard deviations, and 95% confidence intervals of the predictions. Bayes factors are used for evaluating the probability distributions of the predictions, which are essential to structural condition assessments, such as outlier identification and reliability analysis. The performance of the present BDLM has been successfully verified based on the simulated data and the real data obtained from the structural health monitoring system installed on the revolving structure.

A Voronoi cell finite element method for estimating effective mechanical properties of composite solid propellants

Liu-Lei Shen,Zhi-Bin Shen,Hai-Yang Li,Ze-Yuan Zhang 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.11

The mechanical properties of Composite solid propellant (CSP) are the critical material parameters to analyze the structural integrity of propellant grains, and have a significant influence on the life and reliability of solid rocket motors. A Voronoi cell finite element method using an adaptive algorithm in the time domain is proposed for investigating the linear viscoelasticity of CSP in the present paper. A process is brought forward to produce a Representative volume element (RVE) model, which reflects the microstructural features of CSP. Numerical viscoelastic examples are used for varying the accuracy of this method. In addition, finite element simulations are conducted to understand the effect of microstructural morphology and material properties of inclusion on the effective mechanical properties of CSP using the new method. When this method is applied to the design process of CSP, it can reduce the design cost and shorten the design cycle effectively. The current microscopic numerical analysis method can be used to provide guidance for designing and analyzing the mechanical properties of composite viscoelastic materials.

Vibration of nonuniform carbon nanotube with attached mass via nonlocal Timoshenko beam theory

Hai-Li Tang,Zhi-Bin Shen,Dao-Kui Li 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.9

This paper studies the vibrational behavior of nonuniform single-walled carbon nanotube (SWCNT) carrying a nanoparticle. A nonuniformcantilever beam with a concentrated mass at the free end is analyzed according to the nonlocal Timoshenko beam theory. Agoverning equation of a nonuniform SWCNT with attached mass is established. The transfer function method incorporating with theperturbation method is utilized to obtain the resonant frequencies of a vibrating nonlocal cantilever-mass system. The effects of thenonlocal parameter, taper ratio and attached mass on the natural frequencies and frequency shifts are discussed. Obtained results indicatethat the sensitivity of the frequency shifts on the attached mass increases when the length-to-diameter ratio decreases. Tapered SWCNTpossesses higher fundamental frequencies if the taper ratio becomes larger.

Antifungal activity of 3-acetylbenzamide produced by actinomycete WA23-4-4 from the intestinal tract of Periplaneta americana

Xia Fang,Juan Shen,Jie Wang,Zhi-li Chen,Pei-bin lin,Zhi-yu Chen,Lin-yan Liu,Huan-xiong Zeng,Xiao-bao Jin 한국미생물학회 2018 The journal of microbiology Vol.56 No.7

Actinomycetes are well-known for producing numerous bioactive secondary metabolites. In this study, primary screening by antifungal activity assay found one actinomycete strain WA23-4-4 isolated from the intestinal tract of Periplaneta americana that exhibited broad spectrum antifungal activity. 16S rDNA gene analysis of strain WA23-4-4 revealed close similarity to Streptomyces nogalater (AB045886) with 86.6% sequence similarity. Strain WA23-4-4 was considered as a novel Streptomyces and the 16s rDNA sequence has been submitted to GenBank (accession no. KX291006). The maximum antifungal activity of WA23-4-4 was achieved when culture conditions were optimized to pH 8.0, with 12% inoculum concentration and 210 ml ISP2 medium, which remained stable between the 5th and the 9th day. 3-Acetyl benzoyl amide was isolated by ethyl acetate extraction of WA23- 4-4 fermentation broth, and its molecular formula was determined as C9H9NO2 based on MS, IR, 1H, and 13C NMR analyses. The compound showed significant antifungal activity against Candida albicans ATCC 10231 (MIC: 31.25 μg/ml) and Aspergillus niger ATCC 16404 (MIC: 31.25 μg/ml). However, the compound had higher MIC values against Trichophyton rubrum ATCC 60836 (MIC: 500 μg/ml) and Aspergillus fumigatus ATCC 96918 (MIC: 1,000 μg/ml). SEM analysis showed damage to the cell membrane of Candida albicans ATCC 10231 and to the mycelium of Aspergillus niger ATCC 16404 after being treatment with 3-acetyl benzoyl amide. In conclusion, this is the first time that 3-acetyl benzoyl amide has been identified from an actinomycete and this compound exhibited antifungal activity against Candida albicans ATCC 10231 and Aspergillus niger ATCC 16404.

Robust Finite-time Attitude Tracking Control of Rigid Spacecraft Under Actuator Saturation

Hai-Tao Chen,Shen-Min Song,Zhi-Bin Zhu 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.1

This paper investigates the robust finite-time attitude tracking control problem for rigid spacecraft considering the modeling uncertainty, external disturbance and actuator saturation. An auxiliary system is proposed to directly compensate for the saturated control input. First, the basic controller is formulated based on the fast nonsingular terminal sliding mode surface (FNTSMS), the fast-TSM-type reaching law and the auxiliary system in the presence of upper bounded external disturbance. Then, when facing system uncertainty which consists of both modeling uncertainty and external disturbance and has upper bounded first derivative, the extended state observer (ESO) is associated with the first controller to improve the robustness of control system. Furthermore, to handle more general system uncertainty which is upper bounded by a polynomial function of the closed-loop system states, a continuous adaptive controller is designed to compensate for the total system uncertainty on line. The proposed controllers are able to deal with system uncertainty, input singularity and actuator saturation, while simultaneously providing fast finite-time convergence speed for the control system. And the problems of complex parameters selection process and repeated differentiations of nonlinear functions can be avoided. Rigorous stability analyses are given via the Lyapunov stability theory and digital simulations are conducted to illustrate the effectiveness of the proposed controllers.

Modification of Fe/Cu Multilayers under 2-MeV Xe20+ Irradiation

Kong-Fang Wei,Zhi-Guang Wang,Jie Gou,Yan-Bin Sheng,Gen-Ming Jin,Hang Zang,Cun-Feng Yao,Yi-Zhun Ma,Tie-Long Shen 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.6

Multilayers with a structure of Si/[Fe(10 nm)/Cu(10 nm)]5 were deposited on Si(100) substrates and then irradiated at room temperature by using 2-MeV Xe20+. The modifications of the multilayers were characterized using a depth profile analysis of the Auger electron spectroscopy (AES) data and the evolution of crystallite structures of the multilayers were analyzed by using X-ray diffraction (XRD). The AES depth profiles indicated that de-mixing of the Fe and the Cu layers was observed at low ion fluences, but inter-mixing of the Fe and the Cu layers was found at high ion fluences and destroyed the layered structure of the multilayers. The obtained XRD patterns showed that, after irradiation by 2-MeV Xe20+ at 2 × 1016 ions/cm2, the peaks of the multilayers related to a Cu-based fcc solid solution and an Fe-based bcc solid solution phase became visible, which implied that the inter-mixing at the Fe/Cu interface resulted in the formation of new phases. A possible mechanism of modification in the Fe/Cu multilayers induced by ion irradiation is briefly discussed. Multilayers with a structure of Si/[Fe(10 nm)/Cu(10 nm)]5 were deposited on Si(100) substrates and then irradiated at room temperature by using 2-MeV Xe20+. The modifications of the multilayers were characterized using a depth profile analysis of the Auger electron spectroscopy (AES) data and the evolution of crystallite structures of the multilayers were analyzed by using X-ray diffraction (XRD). The AES depth profiles indicated that de-mixing of the Fe and the Cu layers was observed at low ion fluences, but inter-mixing of the Fe and the Cu layers was found at high ion fluences and destroyed the layered structure of the multilayers. The obtained XRD patterns showed that, after irradiation by 2-MeV Xe20+ at 2 × 1016 ions/cm2, the peaks of the multilayers related to a Cu-based fcc solid solution and an Fe-based bcc solid solution phase became visible, which implied that the inter-mixing at the Fe/Cu interface resulted in the formation of new phases. A possible mechanism of modification in the Fe/Cu multilayers induced by ion irradiation is briefly discussed.

Prognostic Significance of Beclin-1 Expression in Colorectal Cancer: a Meta-analysis

Han, Ye,Xue, Xiao-Feng,Shen, Hu-Gang,Guo, Xiao-Bo,Wang, Xu,Yuan, Bin,Guo, Xing-Po,Kuang, Yu-Ting,Zhi, Qiao-Ming,Zhao, Hong Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.11

Objective: Beclin-1 has recently been observed as an essential marker of autophagy in several cancers. However, the prognostic role of Beclin-1 in colorectal neoplasia remains controversial. Our study aimed to evaluate the potential association between Beclin-1 expression and the outcome of colorectal cancer patients. Materials and Methods: All related studies were systematically searched in Pubmed, Embase, Springer and Chinese National Knowledge Infrastructure databases (CNKI), and then a meta-analysis was performed to determine the association of Beclin-1 expression with clinical outcomes. Finally, a total of 6 articles were included in our analysis. Results: Our data showed that high Beclin-1 expression in patients with CRC was associated with poor prognosis in terms of tumor distant metastasis (OR=2.090, 95%CI=1.061-4.119, p=0.033) and overall survival (RR=1.422, 95%CI=1.032-1.959, p=0.031). However, we did not found any correlation between Beclin-1 over-expression and tumor differentiation (OR=1.711, 95%CI=0.920-3.183, p=0.090). In addition, there was no evidence of publication bias as suggested by Egger's tests for tumor distant metastasis (p=1.000), differentiation (p=1.000) and OS (p=0.308). Conclusions: Our present meta-analysis indicated that elevated Beclin-1 expression iss associated with tumor metastasis and a poor prognosis in patients with CRC. Beclin-1 might serve as an efficient prognostic indicator in CRC, and could be a new molecular target in CRC therapy.

Risk Assessment of Breast Cancer in Guangdong, China: A Community-based Survey

Lin, Ying,Shao, Nan,Zhang, Yun-Jian,Wu, Zhuang-Hong,Li, Zhi-Bin,Ren, Ze-Fang,Wang, Shen-Ming Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.6

Objectives: Compared with Western countries, the incidence rates for breast cancer in China are still low. However, breast cancer appears to be hitting Chinese women at a much younger age, with a peak between 40 and 50 years. Furthermore, breast tumors of Asian women have molecular and genetic characteristics that are different from those of Caucasian women. Methods: A community-based study was designed to evaluate the relationship between lifestyles and breast cancer risk in Chinese women residing in Guangzhou. 16,314 subjects completed the questionnaire. Potential confounding factors included sociodemographic characteristics. Results: 33 individuals reported a history of breast cancer, yielding a prevalence rate of 202.3/100000. Associations between subjects' demographic and breast cancer risk factors were assessed. Breast cancer is associated with family history of breast cancer, X-rays received, benign breast disease and hyperlipoidemia or hypercholesteremia with elevated odds ratios. Conclusions: Family history of breast cancer, X-ray received benign breast disease and hyperlipoidemia or hypercholesteremia were significantly associated with risk of breast cancer and may havepotential for breast cancer risk assessment.

Vibration analysis of viscoelastic single-walled carbon nanotubes resting on a viscoelastic foundation

Da-Peng Zhang,Yong-Jun Lei,Cheng-Yuan Wang,Zhi-Bin Shen 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.1

Vibration responses were investigated for a viscoelastic Single-walled carbon nanotube (visco-SWCNT) resting on a viscoelastic foundation. Based on the nonlocal Euler-Bernoulli beam model, velocity-dependent external damping and Kelvin viscoelastic foundation model, the governing equations were derived. The Transfer function method (TFM) was then used to compute the natural frequencies for general boundary conditions and foundations. In particular, the exact analytical expressions of both complex natural frequencies and critical viscoelastic parameters were obtained for the Kelvin-Voigt visco-SWCNTs with full foundations and certain boundary conditions, and several physically intuitive special cases were discussed. Substantial nonlocal effects, the influence of geometric and physical parameters of the SWCNT and the viscoelastic foundation were observed for the natural frequencies of the supported SWCNTs. The study demonstrates the efficiency and robustness of the developed model for the vibration of the visco-SWCNT-viscoelastic foundation coupling system.