Nanomaterials synthesis by a novel phenomenon: The nanoscale Rayleigh-Taylor instability

The Rayleigh-Taylor (RT) interfacial instability has been attributed to physical phenomenon in a wide variety of macroscopic systems, including black holes, laser generated plasmas, and thick fluids. However, evidence for its existence in the nanoscale is lacking. Here we first show theoretically that this instability can occur in films with thickness negligible compared to the capillary length when they are heated rapidly inside a bulk fluid. Pressure gradients developed in the evaporated fluid region produce large forces causing the instability. Experiments were performed by melting Au films inside glycerol fluid by nanosecond laser pulses. The ensuingnanoparticles had highly monomodal size distributions. Importantly, the spacing of thenanoparticles was independent of the film thickness and could be tuned by the magnitude of the pressure gradients. Therefore, this instability can overcome some of the limitations of conventional thin self-organization techniques that rely on film thickness to control length scales

Nanomaterials synthesis by a novel phenomenon: The nanoscale Rayleigh-Taylor instability

The Rayleigh-Taylor (RT) interfacial instability has been attributed to physical phenomenon in a wide variety of macroscopic systems, including black holes, laser generated plasmas, and thick fluids. However, evidence for its existence in the nanoscale is lacking. Here we first show theoretically that this instability can occur in films with thickness negligible compared to the capillary length when they are heated rapidly inside a bulk fluid. Pressure gradients developed in the evaporated fluid region produce large forces causing the instability. Experiments were performed by melting Au films inside glycerol fluid by nanosecond laser pulses. The ensuing nanoparticles had highly monomodal size distributions. Importantly, the spacing of the nanoparticles was independent of the film thickness and could be tuned by the magnitude of the pressure gradients. Therefore, this instability can overcome some of the limitations of conventional thin self-organization techniques that rely on film thickness to control length scales

Controlling Nanoparticles Formation in Molten Metallic Bilayers by Pulsed-Laser Interference Heating

The impacts of the two-beam interference heating on the number of core-shell and embedded nanoparticles and on nanostructure coarsening are studied numerically based on the non-linear dynamical model for dewetting of the pulsed-laser irradiated, thin (< 20 nm) metallic bilayers. The model incorporates thermocapillary forces and disjoining pressures, and assumes dewetting from the optically transparent substrate atop of the reflective support layer, which results in the complicated dependence of light reflectivity and absorption on the thicknesses of the layers. Stabilizing thermocapillary effect is due to the local thickness-dependent, steady-state temperature profile in the liquid, which is derived based on the mean substrate temperature estimated from the elaborate thermal model of transient heating and melting/freezing. Linear stability analysis of the model equations set for Ag/Co bilayer predicts the dewetting length scales in the qualitative agreement with experiment

MODELING TWO-DIMENSIONAL SOFTWARE MULTI-UPGRADATION AND RELATED RELEASE PROBLEM (A MULTI-ATTRIBUTE UTILITY APPROACH)

The today's fast-paced, competitive environment in the field of Science and Technology, demands highly reliable hardware and software in order to achieve new breakthroughs in quality and productivity. In this scenario, first release of software products includes enough features and functionality to make it useful for the customers. Later, software companies have to come up with upgradation or add-ons in their software to survive in the market through a series of releases. Each succeeding upgradation offers some innovative performance or new functionality, distinguishing itself from the past releases. In one-dimensional Software Reliability Growth Models (SRGM) researcher used one factor such as Testing-Time, Testing-Effort or Coverage, etc. but within a two-dimensional SRGM environment, the process depends on two-types of reliability growth factors like Testing-time and Testing-effort. In addition, we also consider the combined effect of bugs encountered during testing of present release and user reported bugs from the operational phase. The model developed in the paper takes into consideration the testing and the operational phase where fault removal phenomenon follows, logistic and Weibull model, respectively. The paper also comprises of formulating an optimal release problem based on Multi-Attribute Utility Theory (MAUT). Lastly, the model validation is done on real dataset of software already released in the market with successive generations. </jats:p