Hybrid arithmetic optimization algorithm with hunger games search for global optimization

Multimedia Tools and Applications - Recently, many population-dependent methods have been proposed. Despite their acceptance in many applications, we are still exploring suggested methods to solve...     

PMN–PT based relaxor ferroelectrics as very smart materials

The basic classification of smart materials and structures is reviewed briefly. The role of nonlinear response for achieving field-tunability of properties is described in simple terms. The observation of the two-way shape-memory effect in a solid solution of lead magnesium niobate (PMN) and lead titanate (PT) for the nominal atomic composition 65:35 is reported. Possible factors influencing the occurrence of the two-way effect are discussed. It is argued that such relaxor ferroelectric ceramics can function as smart materials (rather than serving merely as components of smart structures), because they can meet the “information-reduction” criterion. And they qualify to be called very smart because they have a fairly large number of smartness attributes, including the two-way shape-memory attribute reported here.     

Evaluation of the stability of paper basis-weight profiles using multivariate time series

In the papermaking process, a major concern is maintaining uniform basis weight in the paper sheet. Basis weight, the weight per unit area of the paper, can vary as a function of both time and position across the width of the paper machine. In this short paper, a quantitative index for evaluating the stability, i.e., the similarity of consecutive basis-weight profiles taken across the width of a paper machine, is presented and used to analyze the stability of two production paper machines. The index is determined from autoregressive moving average multivariate time-series models developed for the profile data. With this approach, a more consistent estimate of basis-weight stability can be obtained with fewer profiles by removing the correlation imparted by the papermaking process. Moreover, the parameters of the model can be used to analyze possible sources of basis-weight instability.     

Non-Coherent Pulse Detection with a Large Predetection Bandwidth

For a non-coherent detection circuit with a broad-band pre-detection filter and narrow-band post-detection-filter, equations are obtained for the probability of detection of a pulsed sinusoidal signal embedded in white noise. The equations can be used to calculate the detection probability directly from envelope form, noise power at the input of the circuit and the impulse response of the postdetection filter. The application of the equations is illustrated with reference to a sliding correlator acquisition circuit for PN-code generators.     

Hydrodynamic and heat transfer characteristics of a centrally heated cylindrical enclosure: CFD simulations and experimental measurements

Natural convection in enclosures is of importance in many engineering applications. The stratification arising out of natural convection may be desirable/undesirable depending on applications. In order to control the degree of stratification, understanding of flow pattern and temperature profiles is required. In the present work, transient natural convection in a cylindrical enclosure has been investigated for water with CFD simulations and flow visualization [using particle image velocimetry (PIV) and hot film anemometry (HFA)] over a wide range of parameters namely Rayleigh number (1.08 × 10¹¹ ≤ Ra ≤ 3.76 × 10¹³) and aspect ratio (1 ≤ H/R ≤ 2). The effect of various parameters like pressure, tube diameter and aspect ratio on the extent of stratification has been studied. PIV measurements have been performed to understand the transient flow behavior. Multiple thermocouples were used to measure the temperature profiles. CFD simulations have been performed using SST k–ω model and the results have been compared with the PIV measurements. The CFD simulations have been carried out for 2D axi-symmetric cases and the effect of boundary conditions (free-slip and no-slip) has been investigated. An excellent agreement was found between the CFD predictions and the experimental measurements of flow and temperature patterns. The extent of stratification has been quantified using dimensionless parameters like stratification number and stratification time. The kinetic energy profiles and kinetic energy dissipation profiles show that almost 75% of the enclosure is stratified (after different times depending on Ra number and the aspect ratio). The turbulence parameters were found to weaken with time in the stratified region and these predictions are corroborated with HFA measurements.