Effect of temperature and spring-mass systems on modal properties of Timoshenko concrete beam

Liu, Hanbing,Wang, Hua,Tan, Guojin,Wang, Wensheng,Liu, Ziyu Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.65 No.4

An exact solution for the title problem was obtained in closed-form fashion considering general boundary conditions. The expressions of moment, shear and shear coefficient (or shear factor) of cross section under the effect of arbitrary temperature distribution were first derived. In view of these relationships, the differential equations of Timoshenko beam under the effect of temperature were obtained and solved. Second, the characteristic equations of Timoshenko beam carrying several spring-mass systems under the effect of temperature were derived based on the continuity and force equilibrium conditions at attaching points. Then, the correctness of proposed method was demonstrated by a Timoshenko laboratory beam and several finite element models. Finally, the influence law of different temperature distribution modes and parameters of spring-mass system on the modal characteristics of Timoshenko beam had been studied, respectively.

Muscarinic acetylcholine receptors mediate eIF4B phosphorylation in SNU-407 colon cancer cells

Liu, Ziyu,Cho, Nam Jeong Academic Press 2016 Biochemical and biophysical research communication Vol. No.

<P><B>Abstract</B></P> <P>We have previously shown that muscarinic acetylcholine receptors (mAChRs) promote global protein biosynthesis in SNU-407 colon cancer cells. To gain insight into the molecular mechanisms underlying this event, we examined whether mAChRs regulate the phosphorylation of eIF4B (eukaryotic initiation factor 4B), an essential component of the translation machinery. When SNU-407 cells were treated with the cholinergic agonist carbachol, eIF4B was phosphorylated in a dose- and time-dependent manner. This carbachol effect was almost completely blocked by the muscarinic antagonist atropine, demonstrating that mAChRs specifically mediate the phosphorylation of eIF4B. Carbachol-stimulated eIF4B phosphorylation was significantly reduced by the MEK1/2 inhibitor U0126, indicating that the MEK1/2-ERK1/2 pathway plays an important role in mAChR-mediated eIF4B phosphorylation. However, treating the cells with the phosphoinositide 3-kinase (PI3K) inhibitor LY294002 or the mTORC1 (mammalian target of rapamycin complex 1) inhibitor rapamycin had little effect on carbachol-stimulated eIF4B phosphorylation, suggesting that PI3K and mTORC1 are not the key participants in this process. We also observed that the inhibition of protein kinase C (PKC) by GF109203X greatly diminished carbachol-stimulated eIF4B phosphorylation. Together, our data show that mAChRs modulate eIF4B phosphorylation via the ERK1/2 and PKC signaling pathways in SNU-407 colon cancer cells.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Muscarinic acetylcholine receptors (mAChRs) mediate eIF4B phosphorylation. </LI> <LI> The ERK1/2 signaling pathway is required for mAChR-mediated eIF4B phosphorylation. </LI> <LI> The PI3K-mTORC1 pathway is not important for mAChR-mediated eIF4B phosphorylation. </LI> <LI> Protein kinase C is involved in mAChR-mediated eIF4B phosphorylation. </LI> </UL> </P>

Effect of temperature and spring-mass systems on modal properties of Timoshenko concrete beam

Han-bing Liu,Hua Wang,Guojin Tan,Wensheng Wang,Ziyu Liu 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.65 No.4

An exact solution for the title problem was obtained in closed-form fashion considering general boundary conditions. The expressions of moment, shear and shear coefficient (or shear factor) of cross section under the effect of arbitrary temperature distribution were first derived. In view of these relationships, the differential equations of Timoshenko beam under the effect of temperature were obtained and solved. Second, the characteristic equations of Timoshenko beam carrying several spring-mass systems under the effect of temperature were derived based on the continuity and force equilibrium conditions at attaching points. Then, the correctness of proposed method was demonstrated by a Timoshenko laboratory beam and several finite element models. Finally, the influence law of different temperature distribution modes and parameters of spring-mass system on the modal characteristics of Timoshenko beam had been studied, respectively.

Vibratory characteristics of cracked non-uniform beams with different boundary conditions

Han-bing Liu,Zhigang Wei,Guojin Tan,Yangyang Han,Ziyu Liu 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.1

Non-uniform beams with bending moment of inertia and mass per unit length varying as I(x) = α 1 (1+βx) λ+4 and m(x) = α 2 (1+βx) λ are widely used in various engineering fields, such as the civil and mechanical engineering etc. This paper presents an exact method to investigate the free vibration of cracked non-uniform beams with different conditions. Firstly, the closed form solution for the mode shape functions of the non-uniform beam is obtained based on the Euler-Bernoulli beam theory. Secondly, the beam is divided into several segments according to the different variable form, and each segment is further divided into many sub-segments by cracks. Four undetermined coefficients could represent the mode shape function of each sub-segment by simulating crack with the massless rotational spring. The undetermined transfer relationship in the same segment is obtained based on the principle of the transfer matrix method. The fourorder undetermined coefficient matrix is obtained by using continuity and equilibrium conditions between adjacent segments, and then the characteristic equation of the entire cracked beam is obtained after that. Finally, the results obtained from the finite element method and published papers are used to validate the correctness and reliability of the proposed method. The influences of crack depth, location and boundary conditions on natural frequencies of cracked non-uniform beams are discussed.

The associations of obesity phenotypes with the risk of hypertension and its transitions among middle-aged and older Chinese adults

Ziyue Sheng,Shang Lou,Jin Cao,Weidi Sun,Yaojia Shen,Yunhan Xu,Ziyang Ren,Wen Liu,Qian Yi,Peige Song 한국역학회 2023 Epidemiology and Health Vol.45 No.-

OBJECTIVES: This study aimed to investigate the associations of obesity phenotypes with hypertension stages, phenotypes, and transitions among middle-aged and older Chinese. METHODS: Using the 2011-2015 waves of the China Health and Retirement Longitudinal Study, we conducted a cross-sectional analysis included 9,015 subjects and a longitudinal analysis included 4,961 subjects, with 4,872 having full data on the hypertension stage and 4,784 having full data on the hypertension phenotype. Based on body mass index and waist circumstance, subjects were categorized into 4 mutually exclusive obesity phenotypes: normal weight with no central obesity (NWNCO), abnormal weight with no central obesity (AWNCO), normal weight with central obesity (NWCO), and abnormal weight with central obesity (AWCO). Hypertension stages were classified into normotension, pre-hypertension, stage 1 hypertension, and stage 2 hypertension. Hypertension phenotypes were categorized as normotension, pre-hypertension, isolated systolic hypertension (ISH), isolated diastolic hypertension (IDH), and systolic-diastolic hypertension (SDH). The association between obesity phenotypes and hypertension was estimated by logistic regression. A comparison between different sexes was conducted by testing the interaction effect of sex. RESULTS: NWCO was associated with normal→stage 2 (odds ratio [OR], 1.95; 95% confidence interval [CI], 1.11 to 3.42), maintained stage 1 (OR, 1.62; 95% CI, 1.14 to 2.29), and normal→ISH (OR, 1.39; 95% CI, 1.05 to 1.85). AWCO was associated with normal→stage 1 (OR, 1.75; 95% CI, 1.40 to 2.19), maintained stage 1 (OR, 2.77; 95% CI, 2.06 to 3.72), maintained stage 2 (OR, 2.80; 95% CI, 1.50 to 5.25), normal→ISH (OR, 1.56; 95% CI, 1.20 to 2.02), and normal→SDH (OR, 2.54; 95% CI, 1.72 to 3.75). An interaction effect of sex existed in the association between obesity phenotypes and hypertension stages. CONCLUSIONS: This study highlights the importance of various obesity phenotypes and sex differences in hypertension progression. Tailored interventions for different obesity phenotypes may be warranted in hypertension management, taking into account sex-specific differences to improve outcomes.

On elastic and plastic length scales in strain gradient plasticity

Jinxing Liu,Wen Wang,Ziyu Zhao,Ai Kah Soh 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.61 No.2

The Fleck-Hutchinson theory on strain gradient plasticity (SGP), proposed in Adv. Appl Mech 33 (1997) 295, has recently been reformulated by adopting the strategy of decomposing the second order strain presented by Lam et al. in J Mech Pays Solids 51 (2003) 1477. The newly built SGP satisfies the non negativity of plastic dissipation, which is still an outstanding issue in other SGP theories. Furthermore, it explicitly shows how elastic strain gradients and corresponding elastic characteristic length scales come into play in general elastic-plastic loading histories. In this study, the relation between elastic length scales and plastic length scales is investigated by taking wire torsion as an example. It is concluded that the size effects arising when two sets of length scales are of the same order are essentially elastic instead of plastic.

Experimental Study on Bond Behavior between Section Steel and RAC under Full Replacement Ratio

Chao Liu,Ziyu Fan,Xiaona Chen,Chao Zhu,Haiyang Wang,Guoliang Bai 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.3

Nine specimens of steel reinforced recycled concrete are designed to explore the effect of four factors as the cover thickness of section steel, the embedded length of section steel, the recycled aggregate concrete strength, and the lateral stirrup ratio on bond slip between section steel and recycled aggregate concrete. The test results show that the failure modes of recycled aggregate concrete are as similar as normal concrete; three formulas are proposed for the bond stress between section steel and recycled aggregate concrete, which are fitting well. The mathematical model of bond stress-slip is established through analysis, and the predicted curve is close to the test curve. The research results provide the basis for the numerical simulation analysis of the bond slip for the recycled aggregate concrete under the full replacement ratio.

Environmental fatigue correction factor model for domestic nuclear-grade low-alloy steel

Gao, Jun,Liu, Chang,Tan, Jibo,Zhang, Ziyu,Wu, Xinqiang,Han, En-Hou,Shen, Rui,Wang, Bingxi,Ke, Wei Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.8

Low cycle fatigue behaviors of SA508-3 low-alloy steel were investigated in room-temperature air, high-temperature air and in light water reactor (LWR) water environments. The fatigue mean curve and design curve for the low-alloy steel are developed based on the fatigue data in room-temperature and high-temperature air. The environmental fatigue model for low-alloy steel is developed by the environmental fatigue correction factor (F_en) methodology based on the fatigue data in LWR water environments with the consideration of effects of strain rate, temperature, and dissolved oxygen concentration on the fatigue life.

Analysis and Modeling for Stray Inductance of Commutation Circuit in Indirect Matrix Converter

Yang Mei,Ziyu Liu,Shiheng Niu,Weichao Huang 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

Due to the complex commutation method and process of IMC, the stray inductances of the commutation circuit cannot be negligible, which induces voltage spikes while the power device operates at high frequency. As a result, the voltage stress of power devices is increased, which even causes over voltage damage of the power device. In order to estimate the stray inductance and select appropriate devices, the equivalent circuit model of the commutation circuit is constructed, and the main factors and the effect mechanism are analyzed based on the analysis of the commutation process and circuit of the IMC. A 3D model of the IMC is established by ANSYS software based on the electromagnetic calculation to extract the stray inductance of commutation circuit. The experimental results show that the accurately stray inductance parameters of the commutation circuit can be obtained by using the model, which demonstrates the validity of the analysis and modeling.

Free Vibration of the Cracked Non-uniform Beam with Cross Section Varying as Polynomial Functions

Guo-jin Tan,Yang Liu,Yafeng Gong,Yangfan Shen,Ziyu Liu 대한토목학회 2018 KSCE Journal of Civil Engineering Vol.22 No.11

This paper presents an approach for free vibration analysis of the cracked non-uniform beam with general boundary conditions, whose mass per unit length and bending moment of inertia varying as polynomial functions. Firstly, the general expression of mode shape function of the non-uniform beam with four undetermined coefficients is solved by a generalized power series method based on the Euler-Bernoulli beam theory. Then, the transfer matrix method is combined into the mode shape function of the non-uniform beam to improve the computational efficiency owe to the fewer segments divided by the cracks and joints at the different forms of variable cross-section. The massless rotational springs are adopted to simulate the cracks to derive the transfer relationship of the undetermined coefficients in the same segment. The four undetermined coefficients matrix is obtained by using equilibrium and continuity conditions between two adjacent segments, and then the characteristic equation of the entire cracked beam is formed. Finally, the correctness and reliability of the proposed method in this paper is verified by the methods presented by other published papers and the Finite Element Method (FEM). In addition, the crack parameters on the vibratory characteristics are investigated through the numerical examples.