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.
Experimental study on bond behavior between high-strength grout and deformed steel bars
Abstract Engineers use high-strength grout to connect precast concrete members for its low shrinkage and good fluidity. This paper designed 87 central pull-out specimens using the control variable method to investigate the influence of factors on the rebar-grout bond property such as compressive strength, steel grade, bar diameter, transverse stirrups, and bond length. The test result showed that improving grout compressive strength (85.8 MPa–122.7 MPa) cannot improve the bond strength, which was different from the previous conclusions of concrete pull-out tests. Simplified formulas were presented for calculating the characteristic values of bond strength, residual strength, peak slip, and relative slip of load-holding platform based on parameter analysis. Then, a constitutive model was proposed to predict the full-range bond stress-slip curve of high-strength grout and steel bar specimens from bearing to failure. Finally, FEA models were established to evaluate the applicability and accuracy of the constitutive model.