Exact analytical solution of a polariton model: Undetermined coefficient approach

Using a concise approach with undetermined coefficients, instead of the conventional diagonalization method, we obtain rigorously the energies and analytical wave functions of the ground state and excited states of a polariton model. The results indicate that our method is not only equivalent to the conventional one, but also has its own advantage. We also study several interesting properties of the polariton ground state.published_or_final_versio

Repair of fire-exposed preloaded rectangular concrete columns by postcompressed steel plates

This paper describes an experimental study of axially loaded, fire-exposed, rectangular reinforced concrete (RC) columns repaired with post-compressed steel plates. Seven RC columns with identical section dimensions and reinforcement details were fabricated and tested. Six of them were exposed to a four-hour fire load according to the ISO 834 Standard. After one month of cooling, five of the fire-exposed columns were installed with precambered steel plates which were then post-compressed by a method newly developed by the authors. All columns were tested under axial compression to determine their ultimate load capacity, deformation and ductility. The effects of steel plate thickness, initial precamber displacements and preloading level on the ultimate load capacity of repaired RC columns were investigated. The test results show that up to 72% of the original capacity of the axial load-carrying capacity of fire exposed columns repaired with post-compressed steel plates can be restored. Furthermore, the repaired specimens show better ductility and post-peak deformability. An analytical model was adopted to predict the ultimate axial load capacity of fire exposed columns repaired with post-compressed steel plates. Comparison of the theoretical and experimental results reveals that the analytical model can accurately predict the ultimate axial load capacity of the repaired columns.postprin

Theoretical and experimental study of plate-strengthened concrete columns under eccentric compression loading

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Effect of Sodium Treatment on the Performance of Electrostatic Spray Assisted Vapour Deposited Copper-poor Cu(In,Ga)(S,Se)2 Solar Cells

In our work, eco-friendly, non-vacuum and low cost Electrostatic Spray Assisted Vapour Deposition (ESAVD) method has been used to produce Cu(In,Ga)(S,Se) 2 (CIGS) solar cells. Copper (Cu) deficient (Cu/In + Ga = 0.76) CIGS films were designed to avoid the rather dangerous KCN treatment step for the removal of conductive minor phases of Cu 2 S/Cu 2 Se. A simple sodium (Na) treatment method was used to modify the morphology and electronic properties of the absorber and it clearly improved the solar cell performance. The SEM and XRD results testified a slightly increase of the grain size and (112) crystal orientation in the Na-incorporated CIGS thin films. From the Mott-schottky results, it can be seen that the functions of the Na treatment in our non-vacuum deposited CIGS are mainly used for defect passivation and reduction of charge recombination. Photovoltaic characteristics and j-V curve demonstrated that the dipping of CIGS films in 0.2 M NaCl solution for 20 minutes followed by selenization at 550 °C under selenium vapor resulted in the optimum photovoltaic performance, with j sc , V oc , FF and η of the optimized solar cell of 29.30 mA cm -2 , 0.564 V, 65.59% and 10.83%, respectively

Assessment of vibrations induced in factories by automated guided vehicles

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Ecofriendly and Nonvacuum Electrostatic Spray-Assisted Vapor Deposition of Cu(In,Ga)(S,Se)2 Thin Film Solar Cells

Chalcopyrite Cu(In,Ga)(S,Se)2 (CIGSSe) thin films have been deposited by a novel, nonvacuum, and cost-effective electrostatic spray-assisted vapor deposition (ESAVD) method. The generation of a fine aerosol of precursor solution, and their controlled deposition onto a molybdenum substrate, results in adherent, dense, and uniform Cu(In,Ga)S2 (CIGS) films. This is an essential tool to keep the interfacial area of thin film solar cells to a minimum value for efficient charge separation as it helps to achieve the desired surface smoothness uniformity for subsequent cadmium sulfide and window layer deposition. This nonvacuum aerosol based approach for making the CIGSSe film uses environmentally benign precursor solution, and it is cheaper for producing solar cells than that of the vacuum-based thin film solar technology. An optimized CIGSSe thin film solar cell with a device configuration of molybdenum-coated soda-lime glass substrate/CIGSSe/CdS/i-ZnO/AZO shows the photovoltaic (j-V) characteristics of Voc = 0.518 V, jsc = 28.79 mA cm(-2), fill factor = 64.02%, and a promising power conversion efficiency of η = 9.55% under simulated AM 1.5 100 mW cm(-2) illuminations, without the use of an antireflection layer. This demonstrates the potential of ESAVD deposition as a promising alternative approach for making thin film CIGSSe solar cells at a lower cost

Insight Gained from Using Machine Learning Techniques to Predict the Discharge Capacities of Doped Spinel Cathode Materials for Lithium-Ion Batteries Applications

Abstract The electrochemical potentials of spinel lithium manganese oxide (LMO) have long been plagued by the significant Mn3+ dissolution during long cycle discharging, resulting in rapid capacity fading and short cycle life. Although the doping mechanisms are effective in suppressing these reactions, the correlations of their effects on the material properties and the improved discharging performance still remain uncovered. In this study, seven machine learning (ML) methods are applied to a manually curated dataset of 102 doped LMO spinel systems to predict the initial discharge capacities (IC) and 20th cycle end discharge capacities (EC) from fundamental system properties like material molar mass and crystal structure dimension. Gradient boosting models achieved the best prediction powers for IC and EC with their errors estimated to be 11.90 and 11.77 mAhg−1, respectively. Besides, a higher formula molar mass of doped LMO can improve both capacities and additionally, a shorter crystal lattice dimension with a dopant with smaller electronegativity can slightly improve the value of the IC and EC, respectively. This study demonstrates the great potential of using ML models to both predict the discharging performance of doped spinel cathodes and identify the governing material properties for controlling the discharging performance

Modifying the thermal conductivity of small molecule organic semiconductor thin films with metal nanoparticles

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High performance organic transistor active-matrix driver developed on paper substrate

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