Control of the MBE equipment for growth of nano structures
The technique of molecular-beam-epitaxy (MBE) is the most refined for making semiconductor nanostructures. Nowadays, the growth of self-organised nano structures has been intensively investigated. This technique makes it possible the necessary special sample preparation and the in-situ observation of the nanostructures, growing in a self-organising manner. For the sample preparation and its investigation, we need very accurate control of the MBE equipment. In this paper, we present the programable logical controller (PLC) system wich steer our equipment. Here, we show the control of the heating out system of the vacuum chambers, the control of the furnace of the molecular sources and the control of the moving of the shutters.
Automatización de obturadores de sistema de crecimiento por haces moleculares usando arduino mega en una interfaz de Labview
En este trabajo reportamos el desarrollo de un control de obturadores para un sistema de crecimiento por Haces Moleculares (EHM) o del Ingles Molecular Beam Expitaxy (MBE) utilizando una interfaz gráfica de LabView y la plataforma de Arduino Mega para la adquisición de datos. La técnica de epitaxia por haces moleculares permite controlar espesores a escala nanométrica de muy alta calidad cristalina, para la fabricación de dispositivos electrónicos y optoelectrónicos.
Evaluation of buckling load and dynamic performance of steel shear wall retrofitted with strips made of shape memory alloy
One of the most imperfections of the steel shear wall is out of plane displacements that cause severe damage in both structural and non-structural elements. In this paper, the effects of shape-memory alloys on steel shear walls are investigated. First, a numerical analysis using the finite element method in ABAQUS software has been carried out according to an experimental test. The results of the numerical analysis have been verified with experimental results. Next, shape-memory alloy fibers have been added vertically and horizontally to various parts of the steel shear wall. The results show that retrofitting with the shape-memory alloy reduces the out-of-plane displacement of the steel shear wall under both cyclic and seismic loadings. Besides, the buckling load in the steel shear wall increases when it is retrofitted with the shape-memory alloy. Also, the total out-of-plane movement (accumulated absolute displacements) of the steel shear wall and non-structural damage are controlled by the characteristic of a shape-memory alloy material called “super-elastic”.