• Steel and Composite Structures
• /
• 제48권4호
• /
• pp.419-428
• /
• 2023

In this paper, dynamic and static bending of ball modelled by nanocomposite microbeam by nanoparticles seeing agglomeration is presented. The structural damping is considered by Kelvin-Voigt model. The agglomeration effects are assumed using Mori-Tanaka model. The football ball is modeled by third order shear deformation theory (TSDT). The motion equations are derived by principle of Hamilton's and energy method assuming size effects on the basis of Eringen theory. Using differential quadrature method (DQM) and Newmark method, the static and dynamic deflections of the structure are obtained. The effects of agglomeration and CNTs volume percent, damping of structure, nonlocal parameter, length and thickness of micro-beam are presented on the static and dynamic deflections of the nanocomposite structure. Results show that with increasing CNTs volume percent, the maximum dimensionless dynamic deflection is reduced about 17%. In addition, assuming CNTs agglomeration increases the dimensionless dynamic deflection about 14%. It is also found that with increasing the CNTs volume percent from 0 to 0.15, the static deflection is decreased about 3 times due to the enhance in the stiffness of the structure. In addition, with enhancing the nonlocal parameters, the dynamic deflection is increased about 3.1 times.

• Wind and Structures
• /
• 제24권1호
• /
• pp.43-57
• /
• 2017

The use of nanotechnology materials and applications in the construction industry should be considered for enhancing material properties. However, the nonlinear buckling of an embedded straight concrete columns reinforced with silicon dioxide ($SiO_2$) nanoparticles is investigated in the present study. The column is simulated mathematically with Euler-Bernoulli and Timoshenko beam models. Agglomeration effects and the characteristics of the equivalent composite are determined using Mori-Tanaka approach. The foundation around the column is simulated with spring and shear layer. The governing equations are derived using energy method and Hamilton's principal. Differential quadrature method (DQM) is used in order to obtain the buckling load of structure. The influences of volume percent of $SiO_2$ nanoparticles, geometrical parameters and agglomeration on the buckling of column are investigated. Numerical results indicate that considering agglomeration effects leads to decrease in buckling load of structure.

• Geomechanics and Engineering
• /
• 제12권2호
• /
• pp.327-346
• /
• 2017

Laminated plates have many applications in different industrials. Buckling analysis of these structures with the nano-scale reinforcement has not investigated yet. However, buckling analysis of embedded laminated plates with nanocomposite layers is studied in this paper. Considering the single-walled carbon nanotubes (SWCNTs) as reinforcement of layers, SWCNTs agglomeration effects and nonlinear analysis using numerical method are the main contributions of this paper. Mori-Tanaka model is applied for obtaining the equivalent material properties of structure and considering agglomeration effects. The elastic medium is simulated by spring and shear constants. Based on first order shear deformation theory (FSDT), the governing equations are derived based on energy method and Hamilton's principle. Differential quadrature method (DQM) is used for calculating the buckling load of system. The effects of different parameters such as the volume percent of SWCNTs, SWCNTs agglomeration, number of layers, orientation angle of layers, elastic medium, boundary conditions and axial mode number of plate on the buckling of the structure are shown. Results indicate that increasing volume percent of SWCNTs increases the buckling load of the plate. Furthermore, considering agglomeration effects decreases the buckling load of system. In addition, it is found that the present results have good agreement with other works.

• Structural Engineering and Mechanics
• /
• 제62권5호
• /
• pp.551-565
• /
• 2017

Based on the strain gradient theory (SGT), vibration analysis of an embedded micro cylindrical shell reinforced with agglomerated carbon nanotubes (CNTs) is investigated. The elastic medium is simulated by the orthotropic Pasternak foundation. The structure is subjected to magnetic field in the axial direction. For obtaining the equivalent material properties of structure and considering agglomeration effects, the Mori-Tanaka model is applied. The motion equations are derived on the basis of Mindlin cylindrical shell theory, energy method and Hamilton's principal. Differential quadrature method (DQM) is proposed to evaluate the frequency of system for different boundary conditions. The effects of different parameters such as CNTs volume percent, agglomeration of CNTs, elastic medium, magnetic field, boundary conditions, length to radius ratio and small scale parameter are shown on the frequency of the structure. The results indicate that the effect of CNTs agglomeration plays an important role in the frequency of system so that considering agglomeration leads to lower frequency. Furthermore, the frequency of structure increases with enhancing the small scale parameter.

• Journal of Korea Trade
• /
• 제24권1호
• /
• pp.35-58
• /
• 2020

Purpose - This study examines the determinants of foreign direct investment (FDI) location choice for Chinese firms, focusing on the agglomeration effect for firms of the same nationality. Design/methodology - The empirical data are China's inward FDI from the top 19 economies (excluding tax havens and Taiwan) in terms of FDI during 1997-2015 and China's outward FDI from the top 18 economies (excluding tax havens). This study uses a random effects generalized least squares model for panel data analysis. Findings - The results confirm that both host countries' costs and market conditions and the degree of agglomeration affect these countries' attractiveness for FDI inflows. Specifically, agglomeration has a significant effect on China's inward and outward FDI. This study confirms that the agglomeration of firms of the same nationality has predictive power for multinational enterprises' FDI location choices. The host countries' real GDP and trade openness also positively affect FDI inflows. Interestingly, however, China's production cost has a positive effect. Thus, inward FDI aimed at entering the Chinese market is increasing in recent years relative to the previous efficiency-seeking FDI. Inward FDI in China is therefore the market-entry type, whereas outward FDI by Chinese firms is the market-oriented type. Originality/value - These results suggest that the effects of the potential determinants of Chinese outward FDI are similar to those of inward FDI as China's trade liberalization progresses.

• Computers and Concrete
• /
• 제19권3호
• /
• pp.333-338
• /
• 2017

In this paper, nonlinear vibration of embedded nanocomposite concrete is investigated based on Timoshenko beam model. The beam is reinforced by with agglomerated silicon dioxide (SiO2) nanoparticles. Mori-Tanaka model is used for considering agglomeration effects and calculating the equivalent characteristics of the structure. The surrounding foundation is simulated with Pasternak medium. Energy method and Hamilton's principal are used for deriving the motion equations. Differential quadrature method (DQM) is applied in order to obtain the frequency of structure. The effects of different parameters such as volume percent of SiO2 nanoparticles, nanoparticles agglomeration, elastic medium, boundary conditions and geometrical parameters of beam are shown on the frequency of system. Numerical results indicate that with increasing the SiO2 nanoparticles, the frequency of structure increases. In addition, considering agglomeration effects leads to decrease in frequency of system.

• Steel and Composite Structures
• /
• 제46권1호
• /
• pp.143-152
• /
• 2023

In this paper, static and dynamic bending of nanocomposite micro beam armed with CNTs considering agglomeration effect is studied. The structural damping is considered by Kelvin-Voigt model. The agglomeration effects are assumed using Mori-Tanaka model. The micro beam is modeled by third order shear deformation theory (TSDT). The motion equations are derived by principle of Hamilton's and energy method assuming size effects on the basis of Eringen theory. Using differential quadrature method (DQM) and Newmark method, the static and dynamic deflections of the structure are obtained. The effects of agglomeration and CNTs volume percent, damping of structure, nonlocal parameter, length and thickness of micro-beam are presented on the static and dynamic deflections of the nanocomposite structure. Results show that with increasing CNTs volume percent, the static and dynamic deflections are decreased. In addition, enhancing the nonlocal parameter yields to higher static and dynamic deflections.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2009년도 추계학술대회 논문집
• /
• pp.203-206
• /
• 2009

Agglomeration of catalysts is known as one of the major degradation mechanisms. Reforming of liquid fuel, which requires high temperature over $800^{\circ}C$, accelerates agglomeration of catalysts. In this work, The effects of agglomeration on catalysts activity in partial oxidation reforming conditions were investigated. Metal supported catalysts(Pt-CGO, Ru-CGO) were compared to perovskite-structured catalysts(NECS-P1, NECS-P2). High thermal stability of perovskite-structured catalysts was reported. Micro-reactor installed in electric furnace was used. its Temperature was raised from $800^{\circ}C$ to $1000^{\circ}C$ to accelerate agglomeration effect. To measure rate of agglomeration, BET analysis and CO pulse chemisorption were conducted on catalysts exposed to $1100^{\circ}C$. Metal supported catalysts showed degradation at $1000^{\circ}C$ and The rates were different according to metal supported. On the other hand perovskite-structured catalysts showed no degradation at $1000^{\circ}C$.

• 국제지역연구
• /
• 제20권1호
• /
• pp.209-234
• /
• 2016

This study examines the effects of exporter agglomeration on purely local firms' decision to undertake internationalization and the resultant performance enhancement from internationalization using propensity score matching and difference-in-differences approach. We find that the likelihood of starting to export is higher when purely local firms are located in a region with a higher level of exporter agglomeration, as positive externalities allow them to overcome insufficient internal resources and reduce the large initial foreign market entry costs. We also find that newly exporting firms are more likely to experience greater performance enhancement from exporting when they are locate in a region with a lower level of exporter agglomeration.

• 한국경제지리학회지
• /
• 제25권1호
• /
• pp.41-59
• /
• 2022

우리나라 제조업 성장을 견인해 온 산업단지는 지역 단위에서 제조업 집적의 외부효과를 강화하는 수단으로서 기능하는가? 본 연구는 질문의 답을 위해 제조업 집적과 지역경제 생산성 간 관계에서 산업단지 조절효과를 분석함으로써 기존 선행연구에서 다루지 않은 집적효과 논의를 수행하였다. 2010-2019년 기간의 전국 시군구를 대상으로 한 불균형패널자료를 활용하여 패널분석을 실시하였으며, 전국, 수도권 그리고 비수도권을 구분하여 추정한 결과를 제시하였다. 분석 결과 비수도권의 경우 제조업 특화와 다양성 증가에 따른 긍정적 외부효과가 산업단지를 통해 더욱 강화되어 나타나는 환경이 조성된 반면 수도권에서는 산업단지의 조절효과가 제한적인 것으로 나타났다. 이러한 결과는 제조업 집적효과 극대화, 비수도권의 경제 활성화, 제조업 혁신을 위한 정책수단으로서 산업단지 역할을 재조명할 수 있는 측면에서 시사하는 바가 크다.