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[en] Laser-induced breakdown spectroscopy (LIBS) has been employed for the fast and reliable chemical characterization of silicon used for the photovoltaic industry. Silicon for photovoltaic panels is subject to certain constraints on its purity, and notably must contain low concentration of boron. The use of LIBS could be advantageous because it allows rapid and simultaneous multi-elemental chemical analysis of silicon without any sample preparation. LIBS was applied to boron analysis and a detection limit of 0.23 ppmw was found for optimized gas and pressure conditions. (author)
[en] Highlights: • The sandwich panel with perforated honeycomb-corrugation hybrid core is found to be an excellent sound absorber. • Small perforations on the top facesheet and the corrugation improve sound absorption at low frequencies. • The structure with thinner honeycomb always performs better for sound absorption at low frequencies. • The facesheet is more important to the acoustic-mechanical property than the corrugation. • The Simulated annealing method is found to be effective for the sound absorption optimization of the sandwich structures. An ultra-lightweight sandwich panel with perforated honeycomb-corrugation hybrid (PHCH) core is innovated as a novel sound absorber, which demonstrates great sound absorption as well as excellent mechanical performance. Based on the hybrid-cored sandwich panel, small perforations of different diameters distributed heterogeneously on both the top facesheet and the corrugation are introduced to obtain perfect sound absorption at low frequencies with almost no deterioration in mechanical performance. Theoretical models for sound absorption coefficient and bending stiffness are established, then verified by numerical simulations. With specific mass taken into consideration, an integrated index is proposed to further evaluate the acoustic-mechanical property of the hybrid sandwich. It is found that the PHCH with thinner honeycomb always performs better at low frequencies, and the facesheet is more important to the acoustic-mechanical property than the corrugation. This new kind of lightweight sandwich constructions show promising engineering applications, capable of serving as multi-functional structures with great acoustic and mechanical properties at the same time.
[en] This work aims to contribute to the existing literature by investigating at the impact of financial development on ecological footprint. To achieve this goal, we have employed Driscoll-Kraay panel regression model for a panel of 59 Belt and Road countries in the period from 1990 to 2016. The findings suggest that financial development increases ecological footprint. Moreover, economic growth, energy consumption, foreign direct investment (FDI), and urbanization pollute the environment by increasing ecological footprint. In addition, several diagnostic tests have been applied to confirm the reliability and validity of the results. From the outcome of the study, various policy implications have been proposed for Belt and Road countries to minimize the ecological footprint.
[en] Using new approach proposed by Dynamic relaxation (DR) method, buckling analysis of moderately thick Functionally graded (FG) cylindrical panels subjected to axial compression is investigated for various boundary conditions. The mechanical properties of FG panel are assumed to vary continuously along the thickness direction by the simple rule of mixture and Mori-Tanaka model. The incremental form of nonlinear formulations are derived based on First-order shear deformation theory (FSDT) and large deflection von Karman equations. The DR method combined with the finite difference discretization technique is employed to solve the incremental form of equilibrium equations. The critical mechanical buckling load is determined based on compressive load-displacement curve by adding the incremental displacements in each load step to the displacements obtained from the previous ones. A detailed parametric study is carried out to investigate the influences of the boundary conditions, rule of mixture, grading index, radius-to-thickness ratio, length-to-radius ratio and panel angle on the mechanical buckling load. The results reveal that with increase of grading index the effect of radius-to-thickness ratio on the buckling load decreases. It is also observed that effect of distribution rules on the buckling load is dependent to the type of boundary conditions
[en] Highlights: • The analytical method validated by experimental results is used. • Damage modes of RC panel and missile are illustrated for various cases. • Energy contribution ratios for soft missile impact are presented. - Abstract: Many empirical formulas have been proposed for evaluating local damage to reinforced concrete (RC) structures due to impact by rigid missiles. Most of these formulas have been derived based on the results of tests involving perpendicular impacts on target structures. Thus far, few tests have been conducted considering oblique impact on target structures. As the final goal of this research, we aim to propose a new formula for evaluating local damage due to oblique impact based on previous experimental and simulation results. Herein, we perform simulation analyses for evaluating local damage to RC panels due to oblique impacts at various angles by soft missiles under various impact velocities by using a simulation method that was validated using the results of previous impact experiments. Based on the results of these simulation analyses, we investigate quantitatively the reduction in local damage due to the difference in impact angle and impact velocity. The results of the investigation results and the knowledge obtained from the results are then presented.
[en] This study examines the growth, conservation, neutrality and feedback hypotheses for 49 countries during the period from 1970 to 2010 using panel causality analysis: this technique accounts for both dependence and heterogeneity across the countries. The results provide evidence as to the direction of causality between oil consumption and output and are consistent with the neutrality hypothesis for 24 countries, the growth hypothesis for 5 countries, the conservation hypothesis for 13 countries, and the feedback hypothesis for 7 countries. The findings provide important policy implications for the 49 countries under study. - Highlights: ► Bootstrap panel causality for 49 countries. ► Examines the “growth, conservation, neutrality and feedback” hypotheses for 49 countries during the period from 1970 to 2010.
[en] Optimal configuration of piezoelectric shunt structures is obtained by analyzing admittance of the system. The dissipated energy in the shunt circuit is a function of admittance. Therefore, admittance was selected as the cost function in the process of optimization. Taguchi method was used to determine the optimal configuration of piezoceramic patch bonded on the host structure. Full three dimensional finite element models were analyzed to simulate vibration modes of smart panel and to obtain the admittances of the system. Numerical admittance was validated by experiment. After optimizing process using admittance, the optimal configuration of piezoceramic patch was obtained. It is observed that the performance of smart panel can be predicted by analyzing admittance of piezoelectric structure and admittance can be used as a design index of smart panel
[en] The goal of this session is to provide guidance to medical physicists undergoing the American Board of Radiology certification process in therapeutic medical physics. This panel discussion will focus on parts 2 (computer-based) and 3 (oral) of the examination. Unlike the latter portions of the exam which are specialty-driven, part 1 is universal for all medical physics fields and will not be addressed. This session is structured into different topics that aim to guide the participants on how to successfully prepare for the board exams. The subjects of discussion will include timing and strategies for exam preparation, crucial differences in preparing for the clinical computer-based exam versus the oral exam, what study tools are currently available for each, etc. The panel discussion format will allow the speakers to collectively present their experience and advice relating to each topic and foment audience participation. Learning Objectives: Know the main differences between what is expected for parts 2 and 3 Know different resources for test preparation Know how to formulate a plan to best study for each part based on the specific skill set the two parts require Know how to best present his/her answers during the oral examination – demeanor, answer structure, etc.
[en] In this study, positive-pressure, bending, and drum peel tests were carried out for aluminum honeycomb sandwich panels made of different materials and with different dimensions. The results of these tests not only precisely revealed the relationships between the mechanical properties of aluminum honeycomb sandwich panels and the material dimensions of the face and core layers, the layout mode of the core layer, and the connecting mode between the face layers and core layers, but also determined the reliable mechanical equivalent model. The test results indicate that when the specimen was subjected to the vertical load, the compression properties of aluminum honeycomb sandwich panels were mainly determined by its core layer, while the face layer mainly relieves the axial stress and restrains the deformation of the core layer. In the flexural test, the face layer is the main part subjected to the load, whereas the core layer shows supporting, stabilizing, and strengthening effects, slowing the deformation of the face layer; flexural-tensile properties can be somewhat affected by the layout type of the core layer. The equivalent plate model, honeycomb plate model, and sandwich panel model were screened based on the experimental results, indicating that the sandwich panel model provided a more accurate description. The sandwich panel model was further modified, ultimately resulting in a more effective equivalent model that can accurately reflect the mechanical properties of the aluminum honeycomb sandwich panels.
[en] Reinforced concrete structures subjected to in-plane force exhibit strong nonlinear behaviour due to complex material properties, cracks, interactions between concrete and steel and shear transfer exists in crack surface. Especially if there is crack formations, nonlinear behaviour increases. Thus the prediction of nonlinear behaviour of reinforced concrete includes failure or crushing is very difficult task. Various constitutive equations for concrete stress-strain relationship to predict nonlinear behaviour of reinforced concrete have been proposed. But the study for reinforced concrete analysis model using plastic material model is still demanded. So the purpose of this research is to formulate standard 8-node shell element using plasticity material model for concrete and to analyze nonlinear behaviour of RC panel subjected to in-plane force