A semi-analytical and numerical approach for solving 3D nonlinear cylindrical shell systems

Liming Dai,Kamran Foroutan 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.87 No.5

This study aims to solve for nonlinear cylindrical shell systems with a semi-analytical and numerical approach implementing the P-T method. The procedures and conditions for such a study are presented in practically solving and analyzing the cylindrical shell systems. An analytical model for a nonlinear thick cylindrical shell (TCS) is established on the basis of the stress function and Reddy’s higher-order shear deformation theory (HSDT). According to Reddy’s HSDT, Hooke’s law in three dimensions, and the von-Kármán equation, the stress-strain relations are developed for the thick cylindrical shell systems, and the three coupled nonlinear governing equations are thus established and discretized as per the Galerkin method, for implementing the P-T method. The solution generated with the approach is continuous everywhere in the entire time domain considered. The approach proposed can also be used to numerically solve and analyze the nonlinear shell systems. The procedures and recurrence relations for numerical solutions of shell systems are presented. To demonstrate the application of the approach in numerically solving for nonlinear cylindrical shell systems, a specific nonlinear cylindrical shell system subjected to an external excitation is solved numerically. In numerically solving for the system, the present approach shows higher efficiency, accuracy, and reliability in comparison with that of the Runge-Kutta method. The approach with the P-T method presented is practically sound especially when continuous and high-quality numerical solutions for the shell systems are considered.

Enhanced ketalization activity of cyclohexanone and ethanediol over immobilized ionic liquid in mesoporous materials

Liming Dai,Qian Zhao,Haibo Zhao,Yingying Li,Tingshun Jiang 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.5

Three different mesoporous molecular sieves, including MCM-41, MCM-48, and SBA-15, were synthesized by hydrothermal process and characterized by XRD, BET and TEM. The chlorine-aluminate acidic ionic liquid of 1-butyl-3-methylimidazolium chloride-aluminum chloride ([Bmim]Cl-AlCl3, denoted as Al-ILs) was prepared by twostep method. The immobilized ionic liquid (SBA-15/Al-ILs, MCM-41/Al-ILs, MCM-48/Al-ILs) was prepared through impregnating Al-ILs. The structures of composite catalysts were characterized by XRD, BET, FT-IR, TEM and XPS. The amounts of aluminum present in the resulting composite catalysts were detected by ICP-AES to calculate the amount of AL-ILs impregnated. The ketalization between cyclohexanone and ethanediol was used as the model reaction to test the catalytic activities of the composite catalysts. The effects of molar ratio of the reactants, reaction time, the catalyst dose, as well as the addition of cyclohexane were discussed in detail. Also, catalytic activities of three catalysts with different pore sizes were compared. Under comparable conditions, the SBA-15/Al-ILs composite catalyst exhibited much high catalytic activity and gave a maximum yield that was ca. 85.1%.

Metal-Free Catalysts for Oxygen Reduction Reaction

Dai, Liming,Xue, Yuhua,Qu, Liangti,Choi, Hyun-Jung,Baek, Jong-Beom American Chemical Society 2015 Chemical reviews Vol.115 No.11

<P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/chreay/2015/chreay.2015.115.issue-11/cr5003563/production/images/medium/cr-2014-003563_0080.gif'></P>

Yeast Surface Display of Capsid Protein VP7 of Grass Carp Reovirus: Fundamental Investigation for the Development of Vaccine Against Hemorrhagic Disease

( Shaoxiang Luo ),( Liming Yan ),( Xiaohua Zhang ),( Li Yuan ),( Qin Fang ),( Yong An Zhang ),( Heping Dai ) 한국미생물 · 생명공학회 2015 Journal of microbiology and biotechnology Vol.25 No.12

VP7, an outer capsid protein of grass carp reovirus (GCRV), was expressed and displayed on the surface of Saccharomyces cerevisiae for developing an efficient vaccine against hemorrhagic disease of grass carp. The result of flow cytometry analysis indicated that protein VP7 could be displayed on the surface of yeast cells after inducing with galactose. The expression of VP7 was confirmed by western blot analysis and further visualized with confocal microscopy. The specific antibodies against VP7 generated from mice were detectable from all immune groups except the control group, which was immunized with untransformed yeast cells. The displaying VP7 on glycosylation-deficient strain EBYΔMnn9 was detected to induce a relatively low level of specific antibody amongst the three strains. However, the antiserum of EBYΔM9-VP7 showed relative high capacity to neutralize GCRV. Further neutralization testing assays indicated that the neutralizing ability of antiserum of the EBYΔM9-VP7 group appeared concentration dependent, and could be up to 66.7% when the antiserum was diluted to 1:50. This result indicates that appropriate gene modification of glycosylation in a yeast strain has essential effect on the immunogenicity of a yeast-based vaccine.

Reversible adsorption of conjugated amphiphilic dendrimers onto reduced graphene oxide (rGO) for fluorescence sensing

장동욱,손경주,Liming Dai,백종범 한국고분자학회 2011 한국고분자학회 학술대회 연구논문 초록집 Vol.2011 No.2

Study on the combustion process and work capacity of a micro free-piston engine

Qian Wang,Liming Dai,Kai Wu,Jin Bai,Zhixia He 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.11

With the main idea of exploring combustion conditions and the work capacity of the micro free-piston engine, the study concern isvisualization work including Homogeneous charge compression ignition (HCCI) combustion in the micro-chamber. The initial freepistonvelocity was adjusted to achieve a wide range of compression ratio. The combustion characteristics, the piston motion and pressurevariations under different compression ratios were discussed. Results indicate that the critical combustion condition occurs when thecompression ratio rises to a certain degree. Two-stage combustion characteristics can be observed in micro HCCI combustion processeswith the fuel of the DME/oxygen mixture. The micro-chamber pressure increases with the increase of the compression ratio. The criticalpeak pressure of 5.4 MPa is obtained when the initial piston velocity reaches 15.0 m/s and the diameter and the length of the microchamberis 3 mm and 37 mm, respectively.

Post-buckling analysis of sandwich FG porous cylindrical shells with a viscoelastic core

Kamran Foroutan,Liming Dai 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.45 No.3

In this research, an approach combining a semi-analytical method and an analytical method is presented to investigate the static and dynamic post-buckling behavior of the sandwich functionally graded (FG) porous cylindrical shells exposed to external pressure. The sandwich cylindrical shell considered is composed of a viscoelastic core and two FG porous (FGP) face layers. The viscoelastic core is made of Kelvin-Voigt-type material. The material properties of the FG porous face layer are considered continuous through each face thickness according to a porosity coefficient and a volume fraction index. Two types of sandwich FG porous viscoelastic cylindrical shells named Type A and Type B are considered in the research. Type A shell has the porosity evenly distributed across the thickness direction, and Type B has the porosity unevenly distributes across the thickness direction. The FG face layers are considered in two cases: outside metal surface, inside ceramic surface (OMSICS), and inside metal surface, outside ceramic surface (IMS-OCS). According to Donnell shell theory, von-Kármán equation, and Galerkin’s method, a discretized nonlinear governing equation is derived for analyzing the behavior of the shells. The explicit expressions for static and dynamic critical buckling loading are thus developed. To study the dynamic buckling of the shells, the governing equation is examined via a numerical approach implementing the fourth-order Runge-Kutta method. With a procedure presented by Budiansky-Roth, the critical load for dynamic post-buckling is obtained. The effects of various parameters, such as material and geometrical parameters, on the post-buckling behaviors are investigated.

Nonlinear free and forced vibrations of oblique stiffened porous FG shallow shells embedded in a nonlinear elastic foundation

Kamran Foroutan,Liming Dai 국제구조공학회 2024 Structural Engineering and Mechanics, An Int'l Jou Vol.89 No.1

The present research delves into the analysis of nonlinear free and forced vibrations of porous functionally graded (FG) shallow shells reinforced with oblique stiffeners, which are embedded in a nonlinear elastic foundation (NEF) subjected to external excitation. Two distinct types of PFG shallow shells, characterized by even and uneven porosity distribution along the thickness direction, are considered in the research. In order to model the stiffeners, Lekhnitskii’s smeared stiffeners technique is implemented. With the stress function and first-order shear deformation theory (FSDT), the nonlinear model of the oblique stiffened shallow shells is established. The strain-displacement relationships for the system are derived via the FSDT and utilization of the von-Kármán’s geometric assumptions. To discretize the nonlinear governing equations, the Galerkin method is employed. The model such developed allows analysis of the effects of the stiffeners with various angles as desired, in addition to the quantitative investigation on the influence of the surrounding nonlinear elastic foundations. To numerically solve the problem of vibrations, the 4th-order P-T method is used, as this method, known for its enhanced accuracy and reliability, proves to be an effective choice. The validation of the present research findings includes a comprehensive comparison with outcomes documented in existing literature. Additionally, a comparative analysis of the numerical results against those obtained using the 4th Runge-Kutta method is performed. The impact of stiffeners with varying angles and material parameters on the vibration characteristics of the present system is also explored. The researchers and engineers working in this field may use the results of this study as benchmarks in their design and research for the considered shell systems.

Polyelectrolyte-Functionalized Graphene as Metal-Free Electrocatalysts for Oxygen Reduction

Wang, Shuangyin,Yu, Dingshan,Dai, Liming,Chang, Dong Wook,Baek, Jong-Beom American Chemical Society 2011 ACS NANO Vol.5 No.8

<P>Poly(diallyldimethylammonium chloride), PDDA, was used as an electron acceptor for functionalizing graphene to impart electrocatalytic activity for the oxygen reduction reaction (ORR) in fuel cells. Raman and X-ray photoelectron spectroscopic measurements indicate the charge transfer from graphene to PDDA. The resultant graphene positively charged <I>via</I> intermolecular charge-transfer with PDDA was demonstrated to show remarkable electrocatalytic activity toward ORR with better fuel selectivity, tolerance to CO posing, and long-term stability than that of the commercially available Pt/C electrode. The observed ORR electrocatalytic activity induced by the intermolecular charge-transfer provides a general approach to various carbon-based metal-free ORR catalysts for oxygen reduction.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2011/ancac3.2011.5.issue-8/nn200879h/production/images/medium/nn-2011-00879h_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn200879h'>ACS Electronic Supporting Info</A></P>

Highly Crystalline and Low Bandgap Donor Polymers for Efficient Polymer Solar Cells

최효성,Jun Liu,Liming Dai,김진영 한국고분자학회 2012 한국고분자학회 학술대회 연구논문 초록집 Vol.2012 No.4