Homogeneous Panel Research Articles

Expert Panels with Selective Investigation

Abstract In a model of information disclosure with multiple experts we compare homogeneous panels and diverse panels. The distinguishing feature of our model is selective investigation: there are multiple aspects relevant to decision making and each expert can strategically choose some aspects to investigate. We show that homogeneous panels lead to unbalanced investigation and unbalanced action, while under diverse panels both investigations and actions are balanced. In most circumstances, diverse panels perform better than homogeneous panels.

Natural Resource Endowments and Foreign Direct Investment Flows in Sub-Saharan African Countries

The objective of this paper is to analyze the effects of natural resource endowment on Foreign Direct Investment (FDI) inflows in Sub-Saharan African countries. The data cover the period of 1996-2019 and are extracted from UNCTAD and World Bank databases (WDI, 2019; WGI, 2019). A dynamic model with individual effects is estimated in four partially homogeneous panels using the one-step generalized method of moments. The results obtained show that 1) forest resources have a beneficial but negligible effect on FDI inflows in Sub-Saharan Africa; 2) oil and mining resources have significant and negligible adverse effects on FDI inflows in Central Africa and West Africa, respectively; and 3) oil and mining resources, in contrast, have significant and negligible positive effects on FDI inflows in Southern Africa and East Africa, respectively. Regarding the development of the forestry industry in Sub-Saharan Africa, the strengthening of political stability and control of corruption in Central and West Africa and the strengthening of corruption control in Southern and East Africa are the main economic policy implications.

Wide absorption bandwidth of a light composite absorber based on micro-perforated sandwich panel

We present a light composite absorber consisting of a micro-perforated sandwich panel (MSP) filled with a thin porous materials, to achieve a wide absorption bandwidth. The MSP is of 1 mm thickness scale and possesses the excellent mechanic properties in contrast to a single homogeneous panel. The theoretical model of the light composite absorber is derived by the transfer matrix method, and is well agreed with the experimental results. The proposed absorber predicts a wider 0.5 relative absorption bandwidth and higher absorption coefficient, compared with the micro-perforated panel (MPP) absorber or the double-MPPs absorber. The absorption mechanism owing to the addition of the thin porous materials is conducted by analyzing the reflection coefficient, surface acoustic impedance, acoustic pressure and local velocity. The influences of the thickness, porosity, and hole diameter of the internal components on the absorption bandwidth and absorption peak are discussed. The proposed absorber has a wide scope of potential applications under multi-functional noise-controlled conditions

Oil and stock prices: New evidence from a time varying homogenous panel smooth transition VECM for seven developing countries

AbstractThis paper investigates the relationship between international oil price and stock prices applying the time varying causality testing over the period of 2000M1‐2017M3. The panel unit root and panel cointegration tests considering cross‐section dependence are also employed. A time varying panel smooth transition vector error correction (TV‐PSTRVEC) model is a developed and estimated for testing the presence of non‐linear short‐run and long‐run causality, and cointegrating relationship between stock and oil prices. The empirical findings indicate that short and long‐run causalities between oil price and stock prices are time‐dependent. Moreover, oil price cause stock prices in the long‐run. In the short‐run, neutral effect exists between oil price and stock prices. These two findings are evidence of a strong exogeneity of oil price in time‐dependent regimes which is also supporting the recent arguments and empirical findings.

How do Energy Consumption, Environmental Degradation and Macroeconomic Performance Cause in Developing Countries? An Analysis

The purpose of study is to examine the long run association between energy consumption, environmental degradation and macroeconomic performance in selected developing countries. For this purpose, fifty developing countries are selected from 1990 to 2016. GDP and employment are taken as proxy variables of macroeconomic performance while energy consumption, environmental degradation, labor force, gross capital formation, manufacturing value added, personal remittances received are GDP deflators are other variables. Homogenous panel causality testing is used for explanation of causal and effect linkage of energy consumption, environmental degradation and macroeconomic variables in all selected developing countries after the cross-sectional dependence test and Pedroni test for panel cointegration. The results reveal that there is cross sectional dependency among all variables in selected developing countries. It indicates that the fluctuation in one country will be transmitted to other country which reflects the effectiveness of developing countries collaborative development strategy. Pedroni test for Co-integration and kao test identifies the long run relationship between economic energy consumption, environmental degradation and macroeconomic performance in selected developing countries.

Evolution during Three Ripening Stages of Évora Cheese.

The variability and heterogeneity found in Évora cheeses, Protected Designation of Origin (PDO), can affect consumers’ choices. Assessing the ripening conditions and their effect can be helpful. To study the effect of ripening duration in Évora cheese PDO, sensory and chemical analyses were performed in cheese samples subjected to 30, 60, and 120 days of ripening under controlled conditions (temperature 14 to 15 °C and humidity 65 to 70%). Sensory analysis was conducted with a homogenous panel previously familiarized with the product after a short training period, and chemical analyses including pH, moisture, NaCl content, aw, and salt-in-moisture were determined. Panelists were able to distinguish the differences in the organoleptic characteristics of the three cheese stages, and chemical determinations showed significant differences between stages. Interrater agreement was higher in the sensory evaluation of cheeses with a longer maturation period. As expected, cheeses in the 120 days ripening period presented lower pH, moisture, and water activity and had higher salt-in-moisture content. This stage received the highest scores in hardness and color of the crust, intensity, pungency of the aroma, intensity of taste and piquancy, and firmness and granular characteristics of texture. Overall acceptance of cheese samples was positive, regardless of the ripening stage, which probably reflects both the homogeneity of taster profiles and the previous knowledge of this particular product. The degree of ripeness influences the physical, chemical, and sensory characteristics but does not affect the acceptance of this product by the consumer.

Panel VAR models with interactive fixed effects

SummaryIn the literature, a common feature of panel models with interactive fixed effects is that they model a univariate variable. In this regard, they are incapable of addressing dynamic and simultaneous interactions among a set of macroeconomic variables, a problem that falls within the realm of structural analysis. This paper aims to contribute to the existing literature by studying a homogeneous panel vector autoregression (VAR) model with interactive fixed effects. The panel VAR model in question is flexible in that it can accommodate an arbitrary lag length and observable regressors that can be individual-specific or common. For factor VAR models with both a large cross-section (C) and a large time (T) dimension, we derive the limiting distribution of the interactive fixed estimator, allowing structural analysis to be extended to panel VAR models with interactive fixed effects.

Design strategy for optimising weight and ballistic performance of soft body armour reinforced with shear thickening fluid

This study presents some soft armour panel design strategies using shear thickening fluid (STF) reinforced Kevlar® fabric. The effect of size of silica nano and sub-micron particles on the ballistic performance of soft body armour panels against the small arms ammunition (velocity ~ 430 ± 15 m/s) has been analysed. Two STFs, namely STF-500 and STF-100, were prepared by dispersing silica particles of 500 nm and 100 nm diameter, respectively, in polyethylene glycol (PEG) 200. Kevlar® fabrics were impregnated with both the STFs. Multiple layers (20–24) of fabrics were stitched to prepare 13 soft armour panels which were evaluated for back face signature (BFS) against 9 × 19 mm lead core bullet. Soft armour panels comprising of fabrics impregnated with STF-500 yielded lower BFS than the respective panels comprising of fabrics impregnated with STF-100. This study also revealed that STF impregnation of Kevlar® fabrics can reduce the BFS by 2.5 mm–2.8 mm while keeping the areal density of the panel same (5 kg/m2). The areal density of soft armour panel can be reduced further by 10% (4.5 kg/m2), while keeping the BFS comparable to or lower than that of an STF impregnated homogenous panel, by judiciously placing the STF impregnated fabrics at the rear side while neat fabrics are placed at the strike face of the panel. STF impregnated panels were found to stop the impacting bullet earlier than neat panel.

Three-Dimensional Vibration Analysis of a Functionally Graded Sandwich Rectangular Plate Resting on an Elastic Foundation Using a Semi-Analytical Method.

The three-dimensional vibration of a functionally graded sandwich rectangular plate on an elastic foundation with normal boundary conditions was analyzed using a semi-analytical method based on three-dimensional elasticity theory. The material properties of the sandwich plate varied with thickness according to the power law distribution. Two types of functionally graded material (FGM) sandwich plates were investigated in this paper: one with a homogeneous core and FGM facesheets, and another with homogeneous panels and an FGM core. Various displacements of the plates were created using an improved Fourier series consisting of a standard Fourier cosine series along with a certain number of closed-form auxiliary functions satisfying the essential boundary conditions. The vibration behavior of the FGM sandwich plate, including the natural frequencies and mode shapes, was obtained using the Ritz method. The effectiveness and accuracy of the suggested technique were fully verified by comparing the natural frequencies of sandwich plates with results from investigations of other functionally graded sandwich rectangular plates in the literature. A parametric study, including elastic parameters, foundation parameters, power law exponents, and layer thickness ratios, was performed, and some new results are presented.

Trading Liberties for Security: Groupthink, Gender, and 9/11 Effects on U.S. Appellate Decision-Making

Does groupthink affect court deference to the government in times of heightened security concerns? We argue that male judges serving in homogeneous panels in federal appellate courts modified their behavior post-9/11, but that the presence of a female on the panel mitigated these effects. Using data on the U.S. Court of Appeals from 1978 to 2008 in search-and-seizure cases, we argue that women can safeguard against groupthink effects that otherwise trend toward a more deferential, less rights-oriented approach in times of heightened security. Our findings suggest women mitigate their male colleagues’ shift toward more deferential decisions by affecting panel outcomes that are more consistent with peacetime decisions. These results suggest the important role women exert in collegial panels beyond direct voting patterns. In times of heightened security concerns, panel diversity can avoid groupthink that might stand in the judiciary’s way of providing an effective check on executive and legislative power.

Impact on Clinical Decision Making of Next-Generation Sequencing in Pediatric Epilepsy in a Tertiary Epilepsy Referral Center.

Background. Next-generation sequencing (NGS) describes new powerful techniques of nucleic acid analysis, which allow not only disease gene identification diagnostics but also applications for transcriptome/methylation analysis and meta-genomics. NGS helps identify many monogenic epilepsy syndromes. Pediatric epilepsy patients can be tested using NGS epilepsy panels to diagnose them, thereby influencing treatment choices. The primary objective of this study was to evaluate the impact of genetic testing on clinical decision making in pediatric epilepsy patients. Methods. We completed a single-center retrospective cohort study of 91 patients (43 male) aged 19 years or less undergoing NGS with epilepsy panels differing in size ranging from 5 to 434 genes from October 2013 to September 2017. Results. During a mean time of 3.6 years between symptom onset and genetic testing, subjects most frequently showed epileptic encephalopathy (40%), focal epilepsy (33%), and generalized epilepsy (18%). In 16 patients (18% of the study population), "pathogenic" or "likely pathogenic" results according to ACMG criteria were found. Ten of the 16 patients (63%) experienced changes in clinical management regarding their medication and avoidance of further diagnostic evaluation, that is, presurgical evaluation. Conclusion. NGS epilepsy panels contribute to the diagnosis of pediatric epilepsy patients and may change their clinical management with regard to both preventing unnecessary and potentially harmful diagnostic procedures and management. Thus, the present data support the early implementation in order to adopt clinical management in selected cases and prevent further invasive investigations. Given the relatively small sample size and heterogeneous panels a larger prospective study with more homogeneous panels would be helpful to further determine the impact of NGS on clinical decision making.

Kenaf and Kenaf-Rubberwood Hybrid Particleboards

Kenaf (Hibiscus cannabinus) stem which consists of whole stem (KWS), core (KC) and bast (KB) were used to fabricate homogeneous and hybrid kenaf-rubberwood particleboards. Two types of panels namely homogeneous (100%RW, 100%KWS, 100%KC and 100%KB) and hybrid (70%RW- 30%KWS, 70%RW- 30%KC and 70%RW30%KB) particleboards were manufactured and examined through compaction and void evaluations. Findings show that hybrid panels consisting of 70% RW and 30% KWS and homogeneous 100%KWS give better compaction and less voids as compared to other homogenous and hybrid panels. The panel made from 100% KWS was observed to have more flattened and compressed cells compared to other homogeneous panels. A presence of RW particle apparently reduces the void content and provides better compaction in the hybrid panels

Nonlinear aeroelastic stability analysis of in-plane functionally graded metal nanocomposite thin panels in supersonic flow

This work studies the nonlinear post-instability responses of in-plane bi-directional functionally graded (FG) simply-supported and clamped thin panels. The post-flutter responses of panels subjected to a supersonic airflow are considered as the dynamic case and the post-buckling responses as the static case. The effect of thermal and mechanical in-plane loadings on the panels’ stability and post-instability is analyzed. The first-order piston theory is used for the aerodynamic modeling and the classical plate theory (CPT) along with the nonlinear von-Karman's strains for the structural modeling. The finite element method (FEM) is used for the analysis. The responses of the functionally graded panels are compared to those of the homogeneous panels. Magnesium reinforced by Silicon Carbide nanoparticles composite is considered in this work because of its high stiffness to weight ratio giving it a great potential for aerospace applications. The high stiffening effect of the nano-reinforcements allows the multi-dimensional material grading to maximize the panels’ performance using the minimum amount of the nano-reinforcement.

Theoretical calculation of transmission loss of noise panels

In the paper basic theoretical models of transmission loss calculation are described. Here only single homogeneous isotropic panels are analysed. Three impedance values of one rigid and two flexible body models of panel are described and analysed. As flexible models the thin plate (Kirchhoff-Love plate model) i thick (Mindlin – Reissner model) are analysed.

Physical performance of particleboards using Castor oil-based adhesive

ABSTRACT Reconstituted wood panels are widely used in various branches of the wood industry, such as in the furniture sectors and various segments of urban and rural construction. In Brazil, agricultural and forestry residues are abundantly generated, making feasible the study, development and application of alternative and sustainable materials, produced from the use of these wastes. The aim of this study was to produce high-density homogenous panels with wood residues of Pinus elliottii and oat hulls (Avena sativa), pressed with two types of adhesive, castor oil-based polyurethane and melamine formaldehyde, and to evaluate the physical performance of these panels. The physical performance of the panels was evaluated based on the ABNT NBR 14810: 2006, ANSI A208.1: 1999 and BS EN 312: 2003 standards. Analysis of variance (ANOVA) was performed to test the influence of the factors percentage of oat hull, percentage of adhesive and type of adhesive, and the interactions between these factors on the physical properties of the panels. The results indicated physical properties, in some treatments superior to the requirements stipulated by the consulted standards. It was concluded that the panels produced with the castor oil-based polyurethane adhesive showed better physical performance when compared with the panels produced with the melamine formaldehyde adhesive.

Balance of opinions in expert panels

This note develops a simple model of information disclosure to compare the relative performance between diverse expert panels and homogeneous panels. We identify a burden-of-proof effect, which favors homogeneous panels, and a balance-of-opinions effect, which favors diverse panels. Diverse panels are optimal if and only if experts are relatively well-informed.

Hierarchical anisogrid stiffened composite panel subjected to blast loading: Equivalent theory

Hierarchical anisogrid stiffened panels (HASPs) have two-level stiffeners. The primary stiffeners improve the global stiffness of the HASP and the sub-stiffeners enhance the local stiffness of the mono-cell skin supported by the primary stiffeners. A smearing method was proposed to homogenize the HASP into a homogenous panel, based on two-step equivalences of extensional rigidities and bending rigidities. Dynamic responses of blast-loaded HASPs were analyzed based on the homogenous panel and the mode superposition method and validated by finite element (FE) analysis. Commonly the HASP vibrates like a homogenous panel and the theoretical prediction is accurate. Local mono-cell vibration appears only when the skin and the sub-stiffeners are weak enough. The model was applied to analyze the blast response of a composite protective door. Failure criterion based on maximum strain was proposed to predict the peak blast pressure the HASP can bear. The equivalent theory has good accuracy, providing a feasible way to analyze blast responses of HASPs.

Optimization of in-plane functionally graded panels for buckling strength: Unstiffened, stiffened panels, and panels with cutouts

The work of this paper deals with the in-plane material optimization with the objective of minimizing the amount of the nano-reinforcement required to satisfy the desired buckling constraints. The minimization of the reinforcement is necessary for nano-reinforced composites because the price of the reinforcement is very high. Three types of panels are considered; (1) unstiffened panel, (2) panels with cutouts, and (3) stiffened panels. The in-plane distribution of the reinforcement is represented using the polynomial expansion technique which is also extended to model non-rectangular domains via coordinates transformation. It was found that material grading can saves a very significant amount of the reinforcement up to 200% relative to homogenous panels. The saving of the reinforcement depends on four factors; (1) the problem nature, (2) the boundary conditions, (3) the applied loads, (4) the direction of the material gradings.

Stock markets, banks, and economic growth: Evidence from more homogeneous panels

The present paper investigates whether the link between stock markets, banks, and economic growth becomes more evident as more homogeneous groups of countries are considered. The dynamic panel generalized method of moment (GMM) estimator with Windmeijer (2005) correction is employed using data of European and non-European high-income countries as well as upper and lower middle-income countries averaged over five and three years. Our results indicate that the link between financial development and economic growth depends on the stages of economic growth of the countries. As more homogeneous economies are involved in a panel, a more economically stylized link is uncovered.

Low frequency bandgaps in lightweight metamaterial panels using rotation inertia multiplication

Of all possible features of structural metamaterials, the formation of bandgaps is the most studied one due to its direct application for sound and vibration isolation. While achieving low frequency values for the position of the first bandgap is, in general terms, not an unsurmountable challenge, the combination of material properties such as high stiffness, low density, and reduced size of the unit cell, with low (in absolute terms) frequency bandgaps, may well require some careful consideration. In previous work, we designed panels with a 3D network of resonators, clearly improving the vibration isolation compared to a homogeneous panel with the same weight. Recently, we have devised a novel implementation of inertia amplification, based on coupling the energy of longitudinal waves into the rotational oscillation of inertia elements within the unit cell. In this contribution, we present examples of phononic crystals based on this approach, and we discuss the interaction of acoustic waves with the discussed lattices.