Effectiveness of Truss Supporting During Replacement of Damaged Column in a High-Rise Frame Structure Building

Truss supporting (TS) is a technique to support a building frame for replacing column when its stiffness reduces due to any kind of damage. This paper deals about the effectiveness of TS during replacement of damaged column in a high-rise frame structure building. For the case study of the effectiveness of TS, six columns that are damaged columns at different positions in the ground and first floors were taken into consideration. A suitable type of truss was modelled to transfer the load of damaged column to the lower column just below the damaged column. The numerical analysis of the 2-D frame with undamaged columns, damaged column and damaged column with truss supporting, was carried out using finite element software STAAD Pro 2004. The deflection, axial force, shear force and bending moment of the structural elements (beam & column) for TS case were obtained almost same as their design value

Photoacoustic Identification of Laser-induced Microbubbles as Light Scattering Centers for Optical Limiting in Liquid Suspension of Graphene Nanosheets

Liquid suspensions of carbon nanotubes, graphene and transition metal dichalcogenides have exhibited excellent performance in optical limiting. However, the underlying mechanism has remained elusive and is generally ascribed to their superior nonlinear optical properties such as nonlinear absorption or nonlinear scattering. Using graphene as an example, we show that photo-thermal microbubbles are responsible for the optical limiting as strong light scattering centers: graphene sheets absorb incident light and become heated up above the boiling point of water, resulting in vapor and microbubble generation. This conclusion is based on direct observation of bubbles above the laser beam as well as a strong correlation between laser-induced ultrasound and optical limiting. In-situ Raman scattering of graphene further confirms that the temperature of graphene under laser pulses rises above the boiling point of water but still remains too low to vaporize graphene and create graphene plasma bubbles. Photo-thermal bubble scattering is not a nonlinear optical process and requires very low laser intensity. This understanding helps us to design more efficient optical limiting materials and understand the intrinsic nonlinear optical properties of nanomaterials

A Diamond Shaped Multilevel Inverter With Dual Mode of Operation

This study presents a novel multilevel inverter structure that can operate in both switched capacitor and asymmetric DC source modes. In the first mode, it can produce seven-level output voltage employing two switched capacitors and one single DC supply. The five-level output voltage is produced while operating the second mode. The voltage ratio between the input and output voltage for the capacitor mode is 1:3 (triple voltage gain). During the first mode, the capacitor of the inverter is self -balanced whereas the inverter can produce higher voltage output in the DC source mode. The proposed inverter reduces the total standing voltage in both modes of operations as it can generate the output voltage without requiring any additional H-bridge circuit. The feasibility and predominate features of the proposed inverter have been established by comparing with existing topologies in terms of power components count. Results obtained from this study are validated using simulation employing sinusoidal pulse width modulation (SPWM). A hardware prototype has also been developed for further validation

Bifunctional metal phosphide FeMnP films from single source metal organic chemical vapor deposition for efficient overall water splitting

Developing stable and efficient bifunctional catalysts for overall water splitting into hydrogen and oxygen is a critical step in the realization of several clean-energy technologies. Here we report a robust and highly active electrocatalyst that is constructed by deposition of the ternary metal phosphide FeMnP onto graphene-protected nickel foam by metal-organic chemical vapor deposition from a single source precursor. FeMnP exhibits high electrocatalytic activity toward both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Utilizing FeMnP/GNF as both the anode and the cathode for overall water splitting, a current density of 10 mA cm−2 is achieved at a cell voltage of as low as 1.55 V with excellent stability. Complementary density functional theory (DFT) calculations suggest that facets exposing both Fe and Mn sites are necessary to achieve high HER activity. The present work provides a facile strategy for fabricating highly efficient electrocatalysts from earth-abundant materials for overall water splitting