Optimising continuous microstructures: a comparison of gradient-based and stochastic methods

This work compares the use of a deterministic gradient based search with a stochastic genetic algorithm to optimise the geometry of a space frame structure. The goal is not necessarily to find a global optimum, but instead to derive a confident approximation of fitness to be used in a second optimisation of topology. The results show that although the genetic algorithm searches the space more broadly, and this space has several global optima, gradient descent achieves similar fitnesses with equal confidence. The gradient descent algorithm is advantageous however, as it is deterministic and results in a lower computational cost

An Evolutionary approach to microstructure optimisation of stereolithographic models.

Abstract- The aim of this work is to utilize an evolutationary algorithm to evolve the microstructure of an object created by a stereolithography machine. This should be optimised to be able to withstand loads applied to it while at the same time minimizing its overall weight. A two part algorithm is proposed which evolves the topology of the structure with a genetic algorithm, while calculating the details of the shape with a separate, deterministic, iterative process derived from standard principles of structural engineering. The division of the method into two separate processes allows both flexibility to changed design parameters without the need for re-evolution, and scalability of the microstructure to manufacture objects of increasing size. The results show that a structure was evolved that was both light and stable. The overall shape of the evolved lattice resembled a honeycomb structure that also satisfied the restrictions imposed by the stereolithography machine.

Storage stability of encapsulated barberry's anthocyanin and its application in jelly formulation

The barberry (Berberis vulgaris) extract which is a rich source of anthocyanin was used for encapsulation with three different wall materials i.e., combination of gum Arabic and maltodextrin (GA+MD), combination of maltodextrin and gelatin (MD+GE) and maltodextrin (MD) by spray drying process. In this context, the storage stability of encapsulated pigments was investigated under four storage temperatures (4, 25, 35 and 42 °C), four relative humidities (20, 30, 40 and 50%) and light illumination until 90 days. All wall materials largely increased the half-life of the encapsulated pigments during storage compared with non-encapsulated anthocyanins. MD+GA showed the highest encapsulation efficiency, lower degradation rate in all temperatures and was found as the most effective wall material in stabilizing the pigments. The encapsulated pigments were utilized in coloring jelly powder as an alternative of synthetic color. Sensory evaluation were run to identify best encapsulated natural color concentration in jelly powder formulation according to acceptability by consumers. A jelly with added 7% encapsulated color had higher scores than the commercial jelly containing synthetic color for all the sensory attributes evaluated. Physicochemical properties of produced jelly including moisture content, hygroscopicity, acidity, ash content and texture were not significantly different with control sample while, syneresis and solubility of the samples prepared with encapsulated color was significantly reduced. © 2016 Elsevier Ltd

Microencapsulation optimization of natural anthocyanins with maltodextrin, gum Arabic and gelatin

The barberry (Berberis vulgaris) extract which is a rich source of anthocyanins was used for spray drying encapsulation with three different wall materials, i.e., combination of maltodextrin and gum Arabic (MD + GA), maltodextrin and gelatin (MD + GE), and maltodextrin (MD). Response Surface Methodology (RSM) was applied for optimization of microencapsulation efficiency and physical properties of encapsulated powders considering wall material type as well as different ratios of core to wall materials as independent variables. Physical characteristics of spray-dried powders were investigated by further analyses of moisture content, hygroscopicity, degree of caking, solubility, bulk and absolute density, porosity, flowability and microstructural evaluation of encapsulated powders. Our results indicated that samples produced with MD + GA as wall materials represented the highest process efficiency and best powder quality; the optimum conditions of microencapsulation process for barberry anthocyanins were found to be the wall material content and anthocyanin load of 24.54 and 13.82, respectively. Under such conditions, the microencapsulation efficiency (ME) of anthocyanins could be as high as 92.83. © 2016 Elsevier B.V

The Orbital Structure of Dark Matter Halos with Gas

With the success of the Chandra and XMM missions and the maturation of gravitational lensing techniques, powerful constraints on the orbital structure of cluster dark matter halos are possible. I show that the X-ray emissivity and mass of a galaxy cluster uniquely specify the anisotropy and velocity dispersion profiles of its dark matter halo. I consider hydrostatic as well as cooling flow scenarios, and apply the formalism to the lensing cluster CL0024+16 and the cooling flow cluster Abell 2199. In both cases, the model predicts a parameter-free velocity dispersion profile that is consistent with independent optical redshift surveys of the clusters.Comment: 17 pages, 12 figures; to appear in the Astrophysical Journa

Enhancement of Visual Field Predictions with Pointwise Exponential Regression (PER) and Pointwise Linear Regression (PLR).

PurposeThe study was conducted to evaluate threshold smoothing algorithms to enhance prediction of the rates of visual field (VF) worsening in glaucoma.MethodsWe studied 798 patients with primary open-angle glaucoma and 6 or more years of follow-up who underwent 8 or more VF examinations. Thresholds at each VF location for the first 4 years or first half of the follow-up time (whichever was greater) were smoothed with clusters defined by the nearest neighbor (NN), Garway-Heath, Glaucoma Hemifield Test (GHT), and weighting by the correlation of rates at all other VF locations. Thresholds were regressed with a pointwise exponential regression (PER) model and a pointwise linear regression (PLR) model. Smaller root mean square error (RMSE) values of the differences between the observed and the predicted thresholds at last two follow-ups indicated better model predictions.ResultsThe mean (SD) follow-up times for the smoothing and prediction phase were 5.3 (1.5) and 10.5 (3.9) years. The mean RMSE values for the PER and PLR models were unsmoothed data, 6.09 and 6.55; NN, 3.40 and 3.42; Garway-Heath, 3.47 and 3.48; GHT, 3.57 and 3.74; and correlation of rates, 3.59 and 3.64.ConclusionsSmoothed VF data predicted better than unsmoothed data. Nearest neighbor provided the best predictions; PER also predicted consistently more accurately than PLR. Smoothing algorithms should be used when forecasting VF results with PER or PLR.Translational relevanceThe application of smoothing algorithms on VF data can improve forecasting in VF points to assist in treatment decisions