Narrow Results

The main goal of this research is to analyze the natural frequencies and dynamic response, and to utilize nonlinear control techniques for vibration control of a smart nanocomposite sector plate, while taking into consideration the effects of agglomeration and internal pores. The proposed composite configuration includes a porous core layer reinforced with agglomerated GPLs, as well as two layers of piezoelectric sensors and actuators. Both complete and partial agglomeration states are considered based on the Eshelby–Mori–Tanaka approach to predict the effective properties of the nanocomposite. The mechanical properties of the porous core are characterized using an open-cell metal foam with interconnected pores, notable for their low density and high surface area. The governing equations of motion are derived using Hamilton’s principle, which is based on the First-order Shear Deformation Theory (FSDT) plate theory and the finite element method. The nonlinear fuzzy PID controller is designed as a combination of a fuzzy PI component and a nonlinear PD component. The gains of the PD controller are dynamically adjusted using nonlinear gains to optimize its performance. In addition, a comprehensive analysis has been conducted to examine the effects of geometric dimensions, distribution of reinforcement, weight fractions of nanofillers, parameters of agglomeration, porosity coefficient, porosity pattern, and boundary conditions on the natural frequencies and dynamic response of smart porous nanocomposites. Numerical simulations demonstrate the efficacy of the proposed controller in significantly reducing vibration amplitudes compared to velocity feedback. The velocity feedback controller decreases deflection from 24.39$\mu \mathrm{\text{m}}$ to 8.37$\mu \mathrm{\text{m}}$, whereas the proposed controller achieves 3.66$\mu$m, representing a 56.27% improvement in performance.

This paper investigates the natural frequency and static analysis of a sandwich annular sector plate with a core exhibiting a negative Poisson’s ratio lattice structure, along with facesheets reinforced with agglomerated graphene nanoplatelets (GPL). Both complete and partial agglomeration states are considered using the Eshelby–Mori–Tanaka micromechanical model. The governing equations of motion are derived using Hamilton’s principle, based on First Shear Deformation (FSD) plate theory and the finite element method. The sandwich plates exhibit an ultra-light characteristic, attributable to the auxetic honeycomb core layer, which possesses a negative Poisson’s ratio, and are further reinforced by two laminated skin layers. The study examines the impact of various parameters, including the geometry of the auxetic honeycomb unit cell, the weight fraction of GPL, and the distribution of GPL on the natural frequency, displacement of the center point of the auxetic honeycomb core, and specific absorbed energy of the sandwich plate. The natural frequency decreases with increasing inclination angle, becoming less sensitive as the ratio ${\lambda }_1$, increases. A 57.14% drop occurs for ${\lambda }_1=1$ when the angle rises from 10${}^{\circ }$ to 60${}^{\circ }$, while for ${\lambda }_1=1.5,2$, and 2.5, the reductions are 25.82%, 13.72%, and 9.23%, respectively. Adding 0.1% GPL without agglomeration raises the natural frequency by 237.85%, enhancing stiffness, but full agglomeration cuts this to 12.47%. The X-pattern has the strongest effect, and the O-pattern the least, with distribution patterns becoming more influential as GPL weight fraction rises. In the partial agglomeration state, performance is optimal when $\xi =\zeta$. For a GPL weight fraction from 0.2% to 1%, displacement drops by 77.94% at $\xi =\zeta =0.2$ and by 71.68% at $\xi =0.2,\zeta =0.8$.

Foreign direct investment (FDI) flows into Vietnam have increased significantly in recent years and are distributed unequally between provinces. This paper aims to investigate the locational determinants of FDI in 62 Vietnamese provinces and whether spatial dependence is a significant factor that both researchers and policy-makers should take into account. We report that province-specific per-capita income, secondary education enrolment, labor costs, openness to trade, and domestic investment affect FDI directly within the province itself and have indirect effects on FDI in neighboring provinces. The direct and indirect effects coexist with spill-over effects and spatial dependence between provinces. Our findings indicate that FDI in Vietnam reflects a combination of complex vertical and export platform motivations on the part of foreign investors; and an agglomeration dynamics that may perpetuate the existing regional disparities in the distribution of FDI capital between provinces.

Despite accumulated findings on the effects of agglomeration on productivity of manufacturing industries in Korea, little is known about the determinants of agglomeration. Employing an approach similar to Rosenthal and Strange (2001) [Rosenthal, S and W Strange (2001). The determinants of agglomeration. Journal of Urban Economics, 50(2), 191–229.], but using a different agglomeration index, this study examines whether the three microfoundations of agglomeration economies are important to the geographical concentration of Korean manufacturing industries. While estimation results generally confirm that labor market pooling, input sharing and knowledge spillovers contribute to agglomeration, we found some differences with the previous literature. First, non-manufactured inputs are more influential on agglomeration than manufactured inputs. Secondly, aggregate innovation activities, rather than their share of shipments, are a better measure of knowledge spillovers to explain agglomeration. Thirdly, agglomeration of newly established firms is also influenced by the Marshallian externalities with labor market pooling having a stronger and consistent effect. These results are robust to instrumental variables estimation to control for endogeneity related to knowledge spillovers and labor market pooling.

The paper empirically examines Indian investment in China and its spatial distribution across 17 Chinese provinces during 2005–2015. Indian investments in China have spread across heterogeneous provinces. The location of ventures has been shaped by several provincial characteristics and locational advantages that include infrastructural facilities, lower wages, markets and openness; economic geography forces that include agglomeration of foreign and private firms and policies and engagements of the local governments. As such multiple determinants of location choice can be observed, which provide insights into the locational determinants of firms from one emerging country in another. Chinese inland provinces trying to attract Indian investment need to focus on developing locational advantages at par with the coastal regions and on economic geography. However, the scale of operation of Indian companies in China remains smaller due to several China-specific challenges. Industrial bodies and investment promotion agencies may aid in building firm-capacity to deal with China-specific challenges, with adequate emphasis on the spatial characteristics of provinces, to overcome business challenges. The increase in Indian investment in China shall be beneficial provided the firms and their activities generate complementarity in the bilateral economic relationship between the two countries and in the product and factor markets.

In order to alleviate the agglomeration of nanoparticles in the plating solution, the dispersion effect of binary nanoparticles in Ni–P–Al₂O₃–PTFE composite coating was studied by physical and chemical dispersion methods. The effects of different dispersion methods on the microstructure, hardness and friction coefficient of the composite coating were discussed. Through the performance evaluation of the composite coating, it is found that the effect of using appropriate dispersant and ultrasonic dispersion process is good, which can make the nanoparticles fully dispersed in the solution and evenly distributed in the coating, the composite amount of nanoparticles in the deposition layer is also high. The results show that it has a good effect on improving the wear-resisting and antifriction properties of the composite coatings.

In this work we consider agglomeration-based physical frame discontinuous Galerkin (dG) discretization as an effective way to increase the flexibility of high-order finite element methods. The mesh free concept is pursued in the following (broad) sense: the computational domain is still discretized using a mesh but the computational grid should not be a constraint for the finite element discretization. In particular the discrete space choice, its convergence properties, and even the complexity of solving the global system of equations resulting from the dG discretization should not be influenced by the grid choice. Physical frame dG discretization allows to obtain mesh-independent h-convergence rates. Thanks to mesh agglomeration, high-order accurate discretizations can be performed on arbitrarily coarse grids, without resorting to very high-order approximations of domain boundaries. Agglomeration-based h-multigrid techniques are the obvious choice to obtain fast and grid-independent solvers. These features (attractive for any mesh free discretization) are demonstrated in practice with numerical test cases.

Antimony-doped tin oxide (ATO) nanoparticles were prepared by coprecipitation by packing drying and traditional direct drying (for comparison) methods. The as-prepared ATO nanoparticles were characterized by TG, XRD, EDS, TEM, HRTEM, BET, bulk density and electrical resistivity measurements. Results indicated that the ATO nanoparticles obtained by coprecipitation with direct drying method featured hard-agglomerated morphology, high bulk density, low surface area and low electrical resistivity, probably due to the direct liquid evaporation during drying, the fast shrinkage of the precipitate, the poor removal efficiency of liquid molecules and the hard agglomerate formation after calcination. Very differently, the ATO product obtained by the packing and drying method featured free-agglomerated morphology, low bulk density, high surface area and high electrical resistivity ascribed probably to the formed vapor cyclone environment and liquid evaporation-resistance, avoiding fast liquid removal and improving the removal efficiency of liquid molecules. The intrinsic formation mechanism of ATO nanoparticles from different drying methods was illustrated based on the dehydration process of ATO precipitates. Additionally, the packing and drying time played key roles in determining the bulk density, morphology and electrical conductivity of ATO nanoparticles.

Silver nanoparticles (Ag NPs) are prepared using two different techniques namely hydrothermal and laser ablation methods. The purpose of this study is to find a more suitable method to prepare Ag NPs through comparison that can give stable and size-controlled silver nanoparticles. Techniques used for observations are X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Comparison of results exhibited that hydrothermal process is a more suitable method to prepare silver nanoparticles with smaller uniform size and better yield as compared to laser ablation method. Also, at low temperature, NPs obtained using hydrothermal process provide better control on morphology, high purity and narrow size distribution.

This work investigates the fabrication of microholes in carbon-fiber-reinforced polymer (CFRP) composite by powder-mixed microelectrical discharge drilling (PM$\mu$EDD) method. Initially, pilot experiments were carried out to understand the effect of powder concentration on the machining time and material removal mechanism. Then the full-factorial experimental analysis was performed to investigate the micromachining performance of CFRP composite. The input factors considered for the full-factorial analysis were powder concentration (2, 4, and 6 g/L), capacitance (100, 1000, and 10,000 $\mu$F), and tool rotation (300, 400, and 500 rpm). The regression analysis was carried out to assess the significance of the chosen input factors. The surface morphology of the fabricated microhole was extensively studied to establish the material removal mechanism and failure mechanisms of the composite constituents.

We describe a circular location model in which consumers are distributed according to a symmetric, single-peaked distribution function. Optimal location choices are described and it is determined that equilibria are possible only with one or two firms. Firm strategy is also discussed for greater numbers of firms, and it is shown that even out of equilibrium firms tend to choose locations that are symmetric around the point of highest density, and there can be no agglomeration.

The homogeneous and substantial dispersion of nanoparticles into base fluids is vital since the final properties of any nanolubricant are estimated by their quality of stability. This paper addresses the effect of NiO nanoparticles dispersion into SN500 lubricant oil and its nonisothermal thermo stability. The dispersion of NiO nanoparticles is achieved by ultrasonication method. The thermo stability is estimated by Thermo Gravimetric Analysis (TGA), Differential Thermal Analysis (DTA) and Differential Scanning Calorimetry (DSC). The result shows that the thermo stability of base fluid enhances up to 0.3wt.% particle concentration then it decreases due to agglomeration of dispersed nanoparticles. The findings recommend that 0.1wt.% and 0.3wt.% of NiO-nanolubricant can be used for the temperature-dependent applications up to 200^∘C.

Leading biopharmaceutical firms need to dynamically optimize pipeline portfolios of internally and externally generated product candidates to ensure sustainable growth. This paper provides an empirical analysis of leading global biotechnology firms with respect to technology agglomeration patterns, proximity to alliance partners, and firm performance for the period 1996–2006. Findings suggest that the absolute number of technology and product alliances were approximately twice as important as proximity to partners in terms of firm performance. These results indicate that a strategy of relentless pipeline building, without regard to geographic proximity of alliance partners, may enhance relative and absolute performance of biopharmaceutical industry leaders.

Simulations of the gas fluidization of a cohesive powder were performed using the Stokesian Dynamics method and an agglomeration-deagglomeration model to investigate methods of improving the fluidizability of fine powders. Three techniques (a) high gas velocity (b) vibration-assisted fluidization and (c) tapered fluidizer were used in the simulations which provided detailed information on the bed microscopy such as the motion of 100 particles in a fluidizing vessel along with the formation and destruction of cohesive bonds during collisions. While all three techniques were found to effectively improve the fluidizability of a strongly cohesive powder, we suggest a combination of high velocity fluidization assisted by external vibration of the fluidized bed to minimize entrainment of particles.

Granulation is a unit operation by which larger granules are produced from fine, powdery particles to improve appearance, flow properties and mixedness, reduce dustiness and, in general, produce engineered particles with superior attributes. Agglomeration in wet granulation is achieved by introducing a "binder" fluid onto a shearing mass of fine powders. This paper gives a general overview of the process with emphasis on a simplified granulation model based on a dimensionless parameter containing inertia and viscous dissipation energies between colliding particles: the so-called Stokes number. The model incorporates most common features of all granulation devices (mixers) used in the phar-maceutical industry.

Also described in the paper is a computer simulation that captures the movement of flowing powder in an ideal mixer-granulator with constant shear rate. A fraction of the total number of particles is wet (covered by binder and therefore "sticky") while the rest of the particles are dry. The numerical simulation depicts two distinct regimes of agglomeration found in a typical granulator: granule growth and subsequent breakup. During granule growth-simulations, final granule size and shape distributions are obtained by analyzing the size and shape of formed granules using a pattern-recognition technique. A second kind of simulation, also using rapid granular flow modeling, follows the rotation and deformation of an "agglomerate" held together by a liquid binder. Results from these simulations yield critical values of the Stokes number. Below the critical value, the agglomerates are stable and only rotate in response to shear while above the critical value they break into two or more pieces. At the critical value, they attain a steady elongated shape. Using values of the critical Stokes number, the model predicts the size of formed granules.

The existence of the critical state in which granules attain a characteristic elongated shape is used to measure shear forces in a granulator by employing calibrated "test" particles of known strength. This knowledge is employed in granulation scale-up to determine a kinematic rule that conserves stresses in the small and the large-scale machines. It was found that conserving the magnitude of internal stresses in the moving powder yields granules with similar attributes in granulators of different size.

In this paper, we create three new statistical measures to characterize the spatial patterns and structure of firms and subsectors of industry. The new measures give a direct quantification of the tendency of subsectors to spatially agglomerate, the likelihood of cross-subsector spatial co-agglomeration, and the potential of leading and following behaviors between firms. Unlike the conventional measures which deduce possible agglomeration through deviations from the baseline distribution or distance density, our measures study agglomeration in terms of clustering and co-location behaviors to provide a clear physical picture on spatial agglomeration. With each measure quantifying one of the three different ways in which firms agglomerate spatially, their collective use provides a combined perspective on the agglomeration behavior and location choice of firms that is not available from the conventional measures. We employ this joint application of measures to show that Singapore maritime firms have a propensity to distribute themselves spatially in a manner that allows them to reap the benefits of localization externalities from the agglomeration economy.

This paper analyzes the equity of opportunity in basic education and infrastructure services in seven developing countries, Bangladesh, Bhutan, Indonesia, Pakistan, the Philippines, Sri Lanka, and Viet Nam. The analysis applies a method developed by the World Bank called the Human Opportunity Index, which measures the total contribution of individual socioeconomic and demographic circumstances to inequality of opportunity in accessing basic services. The new and major contribution of the paper, however, is the development of a methodology that quantifies the relative contribution of each circumstance variable to the inequality of opportunity. This contribution is crucial in identifying which underlying inequalities matter most—which can have important policy implications, for instance, in terms of developing better-targeted interventions. Results of the empirical analysis indicate that more needs to be done to improve the distribution of economic benefits. Opportunities to access basic education and infrastructure services in the seven countries vary widely in terms of availability and distribution. The study also finds that inequality of opportunity is driven mainly by per capita household expenditure. This suggests that household poverty plays a crucial role in determining equitable access to basic services.

This paper investigates the evolution of the Japanese economy between 1980 and 2010 with regard to the population and industrial structure of cities. With the rural-to-urban transformation settling by the 1970s, Japan experienced the second stage of urbanization through the integration of nearby cities. This led, on average, to a disproportionately high population growth rate of 24% for a set of core cities during the review period. At the same time, cities experienced substantial changes to their industrial composition: on average, 35% of the manufacturing industries (at the 3-digit level) present in a city in 1980 had left by 2010, while 30% of manufacturing industries located in a city in 2010 had not been present in the same city in 1980. Remarkably, this substantial relocation of populations and industries among cities took place while a simple yet rigid relationship between the size and industrial composition of cities was preserved, characterized by the roughly constant elasticity between the number and average size of cities in which an industry was present. This paper discusses the policy implications of this persistent regularity and the possible underlying mechanisms.

Combining multiple data sets for India, we estimate the elasticity of wages with respect to town population and density between 1% and 2%, which is smaller than estimates in the literature based on district-level analysis. We also find that the employment share of firms with 10 or more workers—which typically describes firms that operate in the formal sector—is positively associated with city population and negatively associated with city density. Town characteristics such as infrastructure availability, geographic location, educational services, and industrial structure also play a role in explaining city productivity and the presence of relatively large firms. Overall, we interpret our results to suggest that there is scope to realize more fully urbanization's potential by addressing issues related to urban planning, infrastructure, and public service delivery, as has been emphasized previously by observers of Indian urbanization.

In December 1993, restrictions to foreign ownership across major Mexican economic sectors were abolished. This paper studies output, industrialization intensity, "international infrastructure", and government expenditures on infrastructure as determinants of FDI inflows into Mexican states over 1994-2001. We conduct a "general to specific" estimation strategy across Mexican states. Telephone lines appear to be very important to FDI as their coefficients are around 2.0 in Random Effects Models. Industrialization is also important, with coefficients varying from 0.62 to 0.67. Allowing for endogeneity between FDI and real output, dynamic GMM panels confirm the robust effects of telephone lines on FDI. International infrastructure thus appears more conducive to FDI than domestic infrastructure, such as interstate and secondary roads. With international infrastructure being a major catalyst of FDI inflows into Mexico, we provide support to ongoing conventional wisdom promoting such type of investment.