Two-dimensional Panel Research Articles

Cross-country Variations in Infrastructure Development, Inflow of FDI and Quality of Institutions

This study tries to investigate the cross-country variations in infrastructure development among different sets of countries with varying institutional rankings, over time, by building five infrastructure indices. Along with building the total/composite infrastructure index, four other (energy, ICT, finance and transport) sub-indices are also built in this study. The strength of our study lies in the fact that we not only find variations in the total infrastructure development but also within the sub-indices. We have introduced the role of country-specific Institutional quality and inflow of FDI empirically in this regard to determine the cross-country variance in infrastructure development. The core hypothesis of our study is that countries that receive a good amount of FDI inflows will have impressive infrastructure development provided the country-specific institutional quality is high. On the contrary, countries with low institutional indexes may not have a positive association between FDI inflows and infrastructure development. However, there are exceptions. For example, institutionally strong countries like Ireland and Belgium should invest more funds to boost their financial infrastructure sector. On the other hand, another institutionally strong country like Norway should develop its transport infrastructure. In this study, we are mainly interested in the joint impact of FDI inflows with the institutional variable on infrastructure development that has been largely neglected in the empirical literature. Using two-dimensional panel data for FDI inflows for 39 countries over the period 2000–20, we find that the conditional effects are positive and significant. From the policy point of view, we identify the possible areas of the infrastructure of a country that needs capital to be invested and at the same time identify some of the countries that need to improve their institutional quality that will eventually lead to improvement in the infrastructure development. The results of our study are robust to different institutional measures and infrastructure indices.

Cross Country Study of Human Capital Formation and USFDI Inflows

Purpose: The neo-classical theory of economic growth features the positive impact of the human capital of an economy on its growth. The inflow of foreign direct investment is one of the main components to carry forward the growth effect, this study investigates the impact of country-specific institutional quality and human capital on the cross-country variations of US-Foreign Direct Investment (FDI) inflows. Our core hypothesis is that Countries with better Human capital will attract more FDI if they have good quality institutions in terms of less risk in investment opportunities. Method: Using a set of panel data of US-Foreign Direct Investment (FDI) inflows for both developed and developing countries over the period 1984-2021. Result: The country-specific quality of institutions reinforces the impact of human capital on the inflow of US foreign direct investment in this study. Using two-dimensional panel data we find strong support for our hypothesis using a two-way fixed effects model. Our results are robust to the alternative measures of institutional quality. Implications: The strength of our approach is that in contrast to the previous works (1) we have used the USFDI inflow across countries that have been widely neglected in the related literature and (2) emphasis has been given to the conditional or joint impact of human capital and country-specific institutional quality in determining the cross-country variations in USFDI inflows.

Exact Eigensolutions of Two-Dimensional Laminated Panel Flutter Based on Mindlin Plate Theory and the First-Order Piston Theory

The panel flutter analysis considering the shear deformation is performed with a particular focus on the exact eigensolutions and the energy transfer. According to Mindlin plate theory and the first-order piston theory, this work obtains the exact eigensolutions of two-dimensional (2D) panel flutter at supersonic speeds. The boundary conditions (BCs) considered include: two edges are simply supported (SS), two edges are clamped (CC), and two edges are clamped and free (CF) respectively. Using the obtained exact eigensolutions, the relations of the kinetic energy, the potential energy and the work done by aerodynamic force are examined for the states of divergent vibration and periodic vibration. Besides, the coupling effect of shear deformation and aerodynamic damping on flutter frequencies is also revealed, and the present results are compared with those of the Galerkin method and the 2D Kirchhoff panel.

Design of a real prototype of a hybrid fuel cell suv: Vehicle "Hércules"

An aeromechanical evaluation of large (over 1 Mw of nominal power) Horizontal Axis Wind Turbines (HAWT’s) is performed is this paper. The strategy is based on the combination of an aerodynamic module, which provides the three-dimensional pressure distribution on the HAWT’s blades, an a structural module which takes such pressure forces as input data in order to compute both, blade deformation and strain and stress distributions over the blade. The aerodynamic module combines the three-dimensional non-linear lifting surface theory approach, which provides the effective incident velocity and angle of attack at each blade section, and a two-dimensional panel method for steady axisymmetric flow in order to obtain the 3D pressure distribution on the blade. Such pressure distribution constitutes the input data for the structural module, which is a finite element package whose output is the blade deformation and strain and stress distribution along the blade, as well as material induced fatigue. This methodology is applied to study a 50 m long blade able to provide a nominal power of 3 Mw.

Economic Policy Uncertainty, Accounting Robustness and Commercial Credit Supply - A Big Data Analysis Based on Accounts Receivable

Abstract In this paper, a two-dimensional panel data model of economic policy uncertainty is investigated based on the individual fixed effects of panel quantile regression, and a nonparametric panel model with individual fixed effects is established. The unfolding of nonparametric penalized spline and the introduction of Bayesian in stratified quantile are utilized to construct regression models applicable to accounting robustness, respectively. In the empirical study, the economic policy uncertainty index, accounting robustness and commercial credit supply are measured respectively. The annual data of China’s Shenzhen and Shanghai A-share listed companies during the period from 2012 to 2021 were selected as the research basis, and Bayesian quantile regression was made on the basis of correlation analysis. The coefficient of commercial credit supply is found to be -0.0821, and the variable RD1 is negatively correlated with economic policy uncertainty. This regression result confirms hypothesis H1 of this paper, suggesting that private firms invest less in innovation when economic policy uncertainty is higher. In the test of economic policy uncertainty by type, the regression coefficients of RD2, EPU, and SIZE are negative, respectively -0.0368, −0.2124, and -0.1458, which indicates that fiscal policy, monetary policy, and exchange rate and capital account policy uncertainty are negatively correlated with the supply of business credit to enterprises. Based on this correlation, this study provides guidance for the development of business credit for enterprises.

Numerical study on the nonlinear characteristics of shock induced two-dimensional panel flutter in inviscid flow

For an aeroelastic system of a two-dimensional elastic panel subjected to an impinging inviscid oblique shockwave, the nonlinear flutter characteristics are affected by many factors such as shock impingement location, cavity pressure and initial perturbation. The effects of the above factors on the variation of system bifurcation type and dynamic behaviors are investigated numerically. A low-fidelity computational method coupled with local piston theory and van Karman plate model, and a high-fidelity computational method coupled with Euler equations and finite element model are used for fluid-structure interaction simulations. Two sets of new findings are unveiled. First, either the variation of shock impingement location or cavity pressure can induce the aeroelastic system to transition between a subcritical bifurcation and a supercritical bifurcation. For some cases, the system bifurcation characteristics exhibit strong sensitivity to these two factors. Second, it is found that in addition to the limit cycle oscillation in the form of a combination of the second and third structural modes, multiple stable limit cycle oscillations due to the coupling of higher-order modes can be triggered by suitable initial perturbations. These limit cycle oscillations have high frequencies and amplitudes, which suggest a higher risk of structural fatigue failure.

Non-Linear Analysis of URM Structures through a Multi-Unit Discretization Approach

This paper presents a benchmark study for the numerical simulation of unreinforced masonry walls under lateral loads using a new modelling strategy. The proposed MUDis (Multi-unit discretization) procedure foresees the discretization of masonry walls into a layout composed of modules, with pre-established geometry and sizes, identified to appropriately reproduce the typical in-plane collapse behaviour of masonry walls subjected to lateral loading. These modules are made of four elastic units separated by nonlinear interface elements that allow to reproduce the failure mechanisms along their surfaces. The mechanical parameters of the interface elements are described through appropriate parametric formulas that modify the “combined cracking-shearing-crushing” model proposed by Lourenco and widely used in the simplified micro-modelling of masonry structures for FE analysis purposes. The reliability of the proposed procedure, already calibrated and validated for two-dimensional panels, is assessed by reproducing the experimental behaviour of a more complex structure subjected to pushover analyses. The benchmark test considered herein is a masonry façade belonging to a three-dimensional building experimentally tested under lateral loads for which results are available in literature.

Nonlinear flutter of 2D variable stiffness curvilinear fibers composite laminates by a higher-order shear flexible beam theory with Poisson’s effect

In this work, the nonlinear supersonic panel flutter characteristics of two-dimensional variable stiffness curvilinear fibres based laminated composite panels are studied using a higher-order shear flexible theory represented by sine function coupled with first-order approximation leading to quasi-aerodynamic theory. The structural formation takes care of geometric nonlinearity with von Karman’s assumptions. The beam constitutive equation is modified for the laminated beam with general lay-up by accounting for Poisson’s effect. The nonlinear dynamic equilibrium equations developed by Lagrangian equations of motion are solved using finite element approach in conjunction with the direct iterative solution procedure. For limit cycle oscillation, critical dynamic pressure is predicted iteratively through eigenvalue analysis, thereby identifying the first coalescence of vibrational modes. Also, the flutter behavior of two-dimensional panel under static differential pressure is investigated considering nonlinear static equilibrium position of panel obtained by Newton-Raphson’s iterative approach and then followed by modes coalescence approach. These solution procedures are tested against the results in literature. A thorough numerical investigation is done to show the effect of the curvilinear fiber path orientation, limited cycle amplitude, static differential pressure, panel thickness, panel end condition flexibilities and thermal environment on the nonlinear supersonic panel flutter of two-dimensional variable stiffness laminated panels.

Study on the bandgap and wave propagation characteristics of tetrachiral and star-shaped hybrid metamaterial

In this paper, an innovative tetrachiral and star-shaped hybrid metamaterial (TSHM) composed of periodic assembly of single-phase lightweight materials is proposed. Based on the finite element method, the band structure of TSHM and the correlation between the bandgaps and geometric parameters are investigated. In addition, the visualization mode provided by the finite element software COMSOL Multiphysics 5.5 is used to explore the formation mechanism of the bandgaps. Furthermore, by drawing iso-frequency contours and group velocities, the directionality of elastic wave propagation in TSHM and the anisotropic behavior of metastructure are intuitively expressed. Finally, the wave regulation effect of the two-dimensional (2D) sandwich panel formed by the TSHM core is studied and the frequency response functions (FRFs) are plotted, which is another way to characterize the bandgap properties. Our research shows that the proposed periodic metamaterial has excellent wave attenuation performance in multiple frequency ranges, which will provide a valuable reference for vibration and noise reduction projects.

Multi-Point Shape Optimization of a Horizontal Axis Tidal Stream Turbine

A method was developed to perform shape optimization of a tidal stream turbine hydrofoil using a multi-objective genetic algorithm. A bezier curve parameterized the reference hydrofoil profile NACA 63815. Shape optimization of this hydrofoil maximized its lift-to-drag ratio and minimized its pressure coefficient, thereby increasing the turbines power output power and improving its cavitation characteristics. The Elitist Non-dominated Sorting Genetic Algorithm (NSGA-II) was employed to perform the shape optimization. A comparative study of two- and three-dimensional optimizations was carried out. The effect of varying the angle of attack on the quality of optimized results was also studied. Predictions based on two-dimensional panel method results were also studied. Predictions based on a two-dimensional panel method and on a computational fluid dynamics code were compared to experimental measurements.

RELATIONSHIP BETWEEN WORKING CAPITAL AND CASH LINES AFFECTS THE PROFIT OF VIETNAM SECURITIES COMPANY

Studying the relationship between working capital and cash flow affecting profitability of Vietnamese securities companies, through tobit model presented in the form of two-dimensional panel data: time dimension (from 2012 to 2019), the space dimension is the enterprise (48 securities companies), corresponding to 370 observations, using STATA 14 software to verify and estimate the tobit model. As a result, the relationship between working capital and cash flow (available cash flow) significantly affects the profitability of Vietnamese securities companies, Average collection period (ACP) has a negative relationship with ROE/ROA, while Average Payout Period (APP) has no significant effect on ROE/ROA. The implication is that securities companies can increase the profitability of the business by shortening the cash conversion cycle, shortening the receivable collection period, that is, for securities companies with positive cash flows, investment should be reduced. working capital to increase profitability.

Influence mechanism of lumped masses on the flutter behavior of structures

It is well known that lumped masses can change the frequency characteristics of the structural system, and aeroelastic flutter happens due to the coalescence of two modes. Therefore, it can be expected to improve the aeroelastic stability by the lumped mass. This paper studies the influence mechanism of the lumped mass on the aeroelastic behaviors of two-dimensional (2D) panels in supersonic airflow, and proposes an axially functionally graded design method using the lumped mass. In this investigation, the finite element method (FEM) is used to formulate the aeroelastic equation of motion for the panels with the lumped mass and spring constraint. For 2D panels with the lumped mass, the local mode coalescence is observed, and the influences of the weight and location of the lumped mass on the flutter stability and their mechanism are analyzed. The optimal ranges for the weight and location of the lumped mass are given out. For 2D panels with the spring constraint, the sudden decrease of the flutter bound due to the mode veering are analyzed, and an effective method to eliminate it by using the lumped mass is proposed. Finally, a structural optimization method based on the axially functionally graded design is proposed.

The suppression of nonlinear panel flutter response at elevated temperatures using a nonlinear energy sink

A nonlinear energy sink (NES) is used to suppress the nonlinear aerothermoelastic response of panels at elevated temperatures. A nonlinear aeroelastic model for a two-dimensional panel with an NES in a supersonic airflow is established using the Galerkin method, with the aerodynamic load being based on first-order piston aerodynamic theory. The model is then used to study the nonlinear dynamic response behavior of a heated panel with an NES to obtain the NES suppression region. The effects of different NES parameters and temperature elevations on the NES suppression region are examined and a design technique is developed to facilitate finding the most suitable combination of parameter values to suppress the nonlinear panel flutter response. The results show that the NES is effective at reducing the aeroelastic response amplitude within a specific range. Varying the installed position, damping, mass ratio and stiffness of the NES will lead to variations in its controlling effect upon the suppression region and the dynamic behavior of the heated panel. An increase in the temperature elevation results in a decrease in the NES suppression region. When the temperature reaches a certain point, the NES suppression region disappears and the NES no longer has any effect on the panel flutter response. Overall, it is found that an NES provides an effect and robust solution, and a wide range of different parameter combinations can be found, that will meet the requirements identified by the proposed design method.

The Impact of Financial Development on Carbon Emission: Evidence from China

This paper studies the impact of financial development on carbon emissions in China from 1997 to 2016. First, this paper uses the entropy method to construct a synthetical index to measure the financial development. Meanwhile, a two-dimensional panel framework is introduced to group provinces in the panel analysis. The estimation results of the time series autoregressive distributed lag model show that for China as a whole, there is a weak carbon emissions reduction effect of financial development, whether it is a long-term effect or a short-term effect. The estimation results of the panel autoregressive distributed lag model also support that an increase in financial development suppresses carbon emissions. Although financial development inhibits carbon emissions both in the short run and in the long run, the absolute value of the long-term coefficient of financial development is significantly greater than that of the short-term coefficient.

Passive Suppression of Panel Flutter Using a Nonlinear Energy Sink

A nonlinear energy sink (NES) is used to suppress panel flutter. A nonlinear aeroelastic model for a two-dimensional flat panel with an NES in supersonic flow is established using the Galerkin method. First-order piston aerodynamic theory is adopted to build the aerodynamic load. The effects of NES parameters on flutter boundaries of the panel are investigated using Lyapunov’s indirect method. The mechanism of the NES suppression of panel flutter is studied through energy analysis. Effects of NES parameters on aeroelastic responses of the panel are obtained, and a design technique is adopted to find a suitable combination of parameter values of the NES that suppresses the panel flutter effectively. Results show that the NES can increase or reduce the onset dynamic pressure of the panel flutter and it can reduce the aeroelastic response amplitude effectively within a certain range of dynamic pressure behind the onset dynamic pressure. The installation position of the NES depends on the direction of the airflow. The robust characteristics should be considered to find the suitable combination of parameter values of the NES.

Imaging Research of Two-Dimensional Photonic-Crystal Flat Lens with Hexagonal Structure

Based on the finite-difference-time-domain method and the plane-wave method, we study the imaging performance of two-dimensional hexagonal-structure photonic-crystal flat panel lens. First, the plane wave expansion method is used to verify that the structure has a negative refraction effect. The equivalent refractive index is – 1 when the normalized frequency is 0.251. The finite-difference-timedomain method is used to study the imaging performance of the structure for the small circular target (radius 1/12 wavelength). The simulation result shows that the imaging resolution of the target is greatly improved by a photonic-crystal flat lens with hexagonal structure. Then the side length of square air hole is changed to study the influence on the imaging performance. We find that the imaging resolution is different for different side lengths. The general trend is that the imaging resolution gradually increases, when the side length of hole increases (from 0.1 a to 0.5 a). There is an optimum resolution when the side length is 0.5 a. The result shows that the imaging performance of the lens can be optimized by changing the side length of holes. It provides a theoretical basis for the practical application of the photonic-crystal flat lens.

Analysis of tourism demand using a multi-dimensional panel gravity model

PurposeThis study aims to estimate the determinants of international tourist flows between destinations by using the panel gravity model.Design/methodology/approachThe multi-dimensional panel gravity model was used to analyse tourism originating from 30 different countries to the 14 most-visited countries in the world between 2008 and 2016. Income (i.e. per capita gross domestic product for both the origin and destination countries), distance between countries, various economic indicators and six dummy variables were added to the gravity model as control variables.FindingsThe results indicated that tourist arrivals depended mainly on economic factors, i.e. income and trade variables were significant determinants of tourist arrivals. The results also suggested that estimated international tourist flows are a negative function of distance, as is postulated in economic theory.Originality/valueIn recent years, gravity models have been used frequently to analyse international tourism demand and have demonstrated their ability to evaluate the effects of various determinants of international tourism for many countries. The literature includes studies that used a two-dimensional panel gravity model to analyse the determinants of tourism demand to a single country from many different countries. This study differs in terms of specificity; in that, it relied on a three-dimensional panel gravity model that allowed for modelling of multiple destination countries. As a result, more comprehensive and general results relative to the determinants of tourism demand were obtained. In addition, the application of a non-nested three-dimensional panel data model, which has limited use, contributes a new perspective to the econometric literature.

On estimation of two-dimensional dynamic panel model with confounders

In this paper, motivated by a real data example about borderline overian tumors, we study a two-dimension dynamic panel models with confounding individual effect for modeling binary panel data. We propose using the maximum likelihood estimation method to estimate the model parameters. The properties of the maximum likelihood estimators are studied. The performance of the proposed estimation method is studied by using a Monte Carlo simulation study. The proposed model and estimation methods are illustrated by the real data example.

An energy flow model for high-frequency vibration analysis of two-dimensional panels in supersonic airflow

Many energy flow models have been proposed for high-frequency forced vibration analysis of structures. In this paper, a novel energy flow model is developed to predict the high-frequency vibration response of panels in supersonic airflow and quantify the effects of supersonic airflow on high-frequency forced vibration characteristics. The additional damping due to supersonic airflow is derived from the motion equation of a two-dimensional panel. The relationship between the wavenumber and the group velocity is introduced to describe the energy transmission property considering the effects of supersonic airflow. Then the energy density governing equation (i.e. energy flow model) is established and solved by the energy flow analysis (EFA) and the energy finite element method (EFEM). Finally, comparing the vibration responses obtained by the present energy flow model with the corresponding exact analytical solutions, the developed energy flow model is verified to be effective for high-frequency vibration analysis of panels in supersonic airflow. Furthermore, the numerical simulations indicate that supersonic airflow can affect the equivalent damping of the propagating elastic waves, and thus change the energy density distribution of the panel.

A new panel for analyzing the impact factors on carbon emission: A regional perspective in China

As the largest carbon emitter in the world, China is under pressure in addressing carbon emission reduction. It is important for the country to understand the impact factors on emission so that proper mitigation measures can be taken. Previous studies have analyzed emission factors through classifying regions mainly by a single economic index or carbon index, whereas this study introduces a two-dimensional panel framework to classify regions. These two dimensions are per capita GDP and carbon intensity. Based on this panel framework, the 30 provinces in China are classified into four regions, namely, high economy and high carbon intensity (Region I), high economy and low carbon intensity (Region II), low economy and low carbon intensity (Region III), and low economy and high carbon intensity (Region IV). The STIRPAT (stochastic impacts by regression on population, affluence, and technology) model and the panel cointegration approach are employed to analyze the impacts of various carbon emission factors in the four classified regions. The results show that the most significant factor for Region I is industrial structure, and that for Regions II, III and IV is energy intensity, population size and per capita GDP respectively. The research results can help decision makers adopt effective emission control measures. The two-dimensional panel framework introduced can be extended for application to examine the emission impact factors at regional or national levels in other countries.