A fuzzy logic based multiobjective genetic algorithm (GA) is introduced and the algorithm is used to optimize micromechanical densification modeling parameters for warm isopressed beryllium powder. In addition to optimizing the 19 main parameters of the model with 17 objective functions (experimental data points), the GA provides a quantitative measure of the sensitivity of the model to each pa...

We have used differential scanning calorimetry (DSC) to measure quantitatively enthalpic changes which accompany gel densification and have related these changes to the evolving gel structure using Raman spectroscopy, gas adsorption, and thermal analysis. We show that the network structure, which results principally from skeletal dehydration (via condensation) during gel densification, is consi...

Three new ceramic batches with no traditional fluxes and 30, 50 and 70 wt.% blast furnace slag were studied. The processes of phase formation and densification were estimated in non-isothermal conditions by differential thermal analysis and dilatometry, respectively. After that the degrees of sintering, obtained after heat-treatment at different temperatures and times, were evaluated measuring ...

Carbon nanotubes (CNTs) have been studied extensively because of their outstanding electrical, mechanical and thermal properties. A common way to integrate CNTs in microsystems is to “grow” them from a catalyst layer using Chemical Vapour Deposition (CVD) [1]. The shape of the microstructures is controlled by patterning the thin catalyst layer which agglomerates to form catalyst nanoparticles. ...

In this work infiltration behavior of mechanical alloyed 75 wt% Cu – 25 wt% WC powders into porous WC compacts were studied. Owing to their ductile nature, initial Cu powders were directly added to mechanical alloying batch. On the other hand initial WC powders were high energy milled prior to mechanical alloying. Contact infiltration method was selected for densification and compacts prepared ...

Until 2000 almost all research in the microwave sintering area was confined to non-metallic materials. However, after the first report by Penn State in 1999 on full sintering of steel powders in microwave, now in the last few years there has been increasing interest in applying microwave energy for processing of variety of metallic materials. The present study is an extension of this work and r...

Blogs form an important on-line social network as they are maintained periodically, and are easily accessible. An important aspect of any blogspace is the relationship of bloggers based on comments. This important aspect is, however, largely ignored in previous works. In this work, we study the evolution of this specific type of social network, blogosphere comment graph. We look at the densific...

How do real graphs evolve over time? What are “normal” growth patterns in social, technological, and information networks? Many studies have discovered patterns in static graphs, identifying properties in a single snapshot of a large network, or in a very small number of snapshots; these include heavy tails for inand out-degree distributions, communities, small-world phenomena, and others. Howe...

The interface atomic structure was proposed to have a critical effect on the microstructure evolution during sintering of ceramic materials. In liquid-phase sintering, spherical grains show the normal grain growth behavior without exception, while angular grains often grow abnormally. The coarsening process of spherical grains with a disordered or rough interface atomic structure is diffusion-c...

Sintering behavior with and without external stress was investigated using undoped and doped (1500 ppm yttria) sub-micron a-alumina powders. The yttria doped alumina showed anomalous behavior with grain size around 0.9 pm, a second peak in densification rate during free sintering and a stagnation followed by a steep increase in flow stress during sinter forging. These were thought to correspond...