Este trabalho descreve a preparação de carbono desordenado de alta área superficial, através da pirólise do nanocompósito TiO 2 /poli(furfuril álcool). Este nanocompósito foi sintetizado pela hidrólise, em meio ácido, da mistura de isopropóxido de titânio e álcool furfurílico. As amostras foram caracterizadas por DRX, FT-IR, espectroscopia Raman e microscopia eletrônica de transmissão. Os resul...

This study presents the characteristics of hot deformation behavior a Al0.3CoCrFeNi high–entropy alloy in temperature and strain rate ranges 1023–1423 K 10–3–10 s–1, respectively. The constitutive flow was modeled based on hyperbolic–sinusoidal Arrhenius–type equations mathematical relation used to observe influence true material constants. To define workability alloy, processing map developed ...

the hot compression tests were carried on x45crniw189 valve steel (x45) in the temperature rangeof 1000– 1200 °c and the strain rate range of 0.004 – 0.5 s-1 in order to study the high temperaturesoftening behavior of this steel. for the exact prediction of flow stress, the effective stress-effectivestrain curves were obtained from experiments under various conditions. on the basis of experimen...

Se presentan los resultados del estudio realizado en cuatro vasijas de gres renano siglo XIX que, siendo recuperadas Cuba, probablemente han sido fabricadas Alemania por encargo la Corona Británica, rellenadas vitriolo propia o Inglaterra y, después transportadas barco a América. El comprende un análisis formal, partiendo concepto cadena operativa, y analítico (TAC, DRX, FRX, SEM-EDX). La sínte...

In view of developing a physics-based constitutive material model for AA7075-T651, the mechanical behavior and microstructure evolution has been studied through compression tests using Gleeble thermo-mechanical simulator. The were performed at wide range temperatures (room temperature (RT), 100, 200, 300, 400 500 °C) with two constant strain rates (0.01 1 s-1). true stress-strain curves depicte...

7000 series Aluminum alloys are widely used in the automotive industries for structural lightweight components due to their exceptional high strength to weight ratio. However, this class of aluminum alloy is difficult to join by conventional fusion welding techniques so Friction stir welding (FSW) widely is used for welding this alloys. The process has been demonstrated to be effective and is c...

Mobile devices such as notebooks and smart phones have replaced the personal computer as main personal information devices. These devices drive a strong demand for wireless networks and wireless communication for the rapidly growing number of Internet users. Since mobile terminals will be severely constrained by their limited battery endurance, it is essential that new protocols and control mec...

The next generation wireless networks are expected to converge into a ubiquitous architecture, which includes high-speed cellular networks, wireless local area networks (WLANs), mobile ad hoc networks, peer-to-peer networks, wireless metropolitan area networks (WMANs), etc. The increasing demand of wireless multimedia services has motivated the development of broad wireless access in the hetero...