Distribution of Expenditures for Research and Development-Dynamic Analysis Based on Composite Concentration Coefficients

The dynamic analysis of distribution of expenditures for research and development aims to identify concentration tendencies in this domain.The analysis is performed by calculating composite concentration coefficients,as these coefficients allow simultaneous(synthesized)expression of existing concentrations in cases where multiple criteria for expressing concentration exist.In this work,the observation was made on a respectable sample of 52 countries in the period from 1997 to 2021.The following variables are included in the analysis:population,gross domestic product,gross domestic product per capita,gross domestic expenditure on research and development absolutely and per capita and human development index.Composite concentration coefficients were derived based on previously calculated concentration coefficients according to the criteria of population size and gross domestic product,gross domestic product per inhabitant and social development index.Calculation of composite concentration coefficients was performed by extrapolation based on standardized regression coefficients from the corresponding regression models.Based on the conducted analysis and obtained results,it can be concluded that a relatively high concentration of gross expenditures for research and development is evident,which has been significantly reduced in the observed time period.

Polypyrrole Chitosan Cobalt Ferrite Nanoparticles Composite Layer for Measuring the Low Concentration of Fluorene Using Surface Plasmon Resonance

Fluorene is a polycyclic aromatic hydrocarbon, which is a hazardous toxic chemical in the environment. The measurement of low concentrations of fluorene is a subject of intense interest in chemistry and in the environment. Polypyrrole chitosan cobalt ferrite nanoparticles are prepared using the electrochemical method. The prepared layers are characterized using field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and energy dispersive spectroscopy. The layers are used to detect fluorene using the surface plasmon resonance technique at room temperature. The composite layer is evaluated after detection of fluorene using atomic force microscopy. The fluorene is bound on the layer, and the shift of the resonance angle is about 0.0052°, corresponding to the limitation of 0.01 ppm.

Assessment of composite failure and ultimate strength without experiment on composite

This paper attempts to estimate the ultimate strength of a laminated composite only based on its con- stituent properties measured independently. Three important issues involved have been systematically addressed, i.e., stress calculation for the constituent fiber and matrix materials, failure detection for the lamina and laminate upon the internal stresses in their constituents, and input data determination of the constituents from monolithic measurements. There are three important factors to influence the accuracy of the strength prediction. One is the stress concentration factor （SCF） in the matrix. Another is matrix plasticity. The third is thermal residual stresses in the constituents. It is these three factors, however, that have not been sufficiently well realized in the composite community. One can easily find out the elastic and strength parameters of a great many laminae and laminates in the current literature. Unfortunately, necessary information to determine the SCF, the matrix plasticity, and the thermal residual stresses of the composites is rare or incomplete. A useful design methodology is demonstrated in the paper.