Optimum discrete design of steel tower structures using optics inspired optimization method

This paper presents an optics inspired optimization (OIO) method for optimum design of steel tower structures with discrete variables. Inspired by the optical characteristics of concave and convex mirrors, OIO tries to solve optimization problem. In OIO, the surface of the objective function to be minimized is considered as a reflecting wavy mirror consisting of peaks and valleys. To generate a new solution (artificial image point) from a given solution (artificial object/light point) in the search space, it is assumed that the artificial ray glittered from the artificial light point is reflected back artificially by the function surface in which each peak is considered as a convex mirror and each valleys is treated as a concave mirror. Then, the artificial image point is formed by the theory of optics in Physics, and a new solution is generated in the search space accordingly. Numerical experiments have been conducted on 4 benchmark design examples with discrete variables, and the results obtained by OIO are compared to those reported in the literature. The results show that OIO can produce high quality solutions and show a relatively fast convergence rate.     

Simulation and analysis of flow in the injection chamber of die casting machine during the slow shot phase

A three-dimensional numerical model, developed on the basis of the finite difference method and the volume fluid method, is used to analyze the mechanism of the liquid metal flow and the possibility of air entrapment in the injection chamber of die casting machine during the slow shot stage. The model gives designers a clear overall picture of the slow shot process and enables them to optimize the injection parameters.     

Replacing Dietary Fish Oil with Vegetable Oil Blends in Female Rainbow Trout Brood Stock Does Not Affect Breeding Quality

To determine the effects of replacing fish oil (FO) with a mixture of vegetable oils (VO) in plant protein-rich diets on reproductive performance, the fatty acid profile of embryos as well as health indices of female rainbow trout (Oncorhynchus mykiss) brooders (initial mean body weight, 1.8 ± 0.1 kg), a 3-month feeding trial was conducted. Four isoproteic (ca. 42%) and isoenergetic (ca. 20 MJ/kg) diets were formulated in which 50% (FO50/VO50), 75% (FO25/VO75), and 100% (VO100) of FO were replaced by a mixture of VO, whereas the control diet (FO100) was prepared with FO as the major source of lipid. Fish fed the VO100 had the lowest fertilization (73.0 ± 2.5%), survival at eyed-embryo stage (62.5 ± 5.0%), and hatching rate (56.0 ± 4.7%) rates. Brood fish fed the FO50/VO50, FO25/VO50, and VO100 diets had higher levels of saturated and monounsaturated fatty acids in embryos in comparison with fish fed FO100 diet. The levels of docosahexaenoic acid of embryos gradually decreased during embryogenesis in all treatments, whereas the concentrations of eicosapentaenoic acid was greatly increased at hatching day (35 days after spawning). Regarding serum biochemical parameters, fish fed the VO100 diet had the highest serum glucose, cholesterol, and low-density lipoprotein levels. The results of the current study revealed that replacement of dietary FO with a mixture of VO up to 75% did not have any adverse effects on reproductive performance and health indices of O. mykiss females.     

Optimal controller placement in large scale software defined networks based on modified NSGA-II

Software Defined Network (SDN) is an emerging approach to overcome challenges of traditional networks. One particularly important issue in SDN architectures is that of controller placement problem (CPP), i.e., deploying a desired number of controllers within a network while some possibly conflicting requirements have to be fulfilled. A single optimal placement may not be possible and decision makers need to seek for an appropriate trade-off among the metrics. Although an exhaustive evaluation of all possible placements can be practically performed well for small and medium-sized networks, regarding realistic time and resource restrictions, heuristic approaches are required for large-scale networks. Hence, a heuristic called Multi-Start Hybrid NSGA-II (MHNSGA-II) is introduced which yields faster computation times and needs reasonable memory to perform. The obtained results on several topologies extracted from Internet Topology Zoo showed the efficiency of the proposed approach.     

Silver cluster supported on nitrogen-doped graphene as an electrocatalyst with high activity and stability for oxygen reduction reaction

An Ag₈ cluster deposited on three different types of nitrogen (N)-doped graphene was studied using density functional theory calculations with empirical pair potentials (DFT-D). Among the different kinds of N-doped graphene, the pyridinic-N₃ (P-N₃) type can act as the best anchor position to stabilize Ag₈. In addition, it is found that supported Ag₈ clusters show higher activity in oxygen reduction reaction compared to unsupported clusters due to significant decrease in O₂ adsorption energy and higher charge transfer to O₂. Electron transfer from Ag to O₂ leads to the elongation of the OO bond, which facilitates the breaking of this bond in the oxygen reduction reaction. All results suggest that N-doped graphene support can play a significant role in the chemical reactivity of a Ag₈ cluster in oxygen reduction reaction.     

Underlying mechanics of active nanocomposites with tunable properties

This paper proposes the development of a new class of nanotube-based piezoelectric polymeric composites with controllable bond expansion and contraction in the interface of nanotube and matrix for use in next-generation structural vibration control systems. It is theoretically shown that through applying external electrical field, the quality of adhesion between nanotube and the matrix at nanoscale can be imparted to result in novel engineered composites at macroscale with tunable mechanical properties ranging from stiffer structure to better damper, the attributes that are essential for structural vibration control. Along this line, two classes of nanotubes; namely, carbon nanotubes (CNTs) and boron nitride nanotubes (BNNTs), are investigated. It is demonstrated that BNNTs possess better tunability compared to CNTs due to their outstanding molecular crystalline structure. More specifically, it is shown that mechanical properties of BNNT-based structures are more sensitive to the variation of separation distance in the interphase zone, and the stick-slip mechanism, which is responsible for damping change, can easily occur in BNNT-reinforced piezoelectric polymers.     

Expandable styrene/methyl methacrylate copolymer: Synthesis and determination of VOCs by combined thermogravimetry/differential thermal analysis‐gas chromatography/mass spectrometry

Parts cast of metals using expandable polystyrene foams may have an unacceptable amount of surface defects, such as lustrous carbon. The use of foams made of styrenic/acrylic copolymers can improve the quality of foam molds and metal parts made using such molds. Lost foam copolymer was synthesized by suspension copolymerization of styrene and methyl methacrylate. The polymerization was carried out in the presence of blowing agents. The decomposition products of lost foam beads were studied by a method composed of the thermogravimetry/differential thermal analysis (TG/DTA) and gas chromatography/mass spectrometry (GC/MS). With these systems, the TG/DTA data can be combined with a GC separation and MS identification methods. This combined method improves the analysis of the decomposition products of lost foam beads and enables the precise identification of the amount and the nature of volatile organic compounds (VOCs) trapped during suspension polymerization. The results obtained from the combined method were verified for the nature and amount of VOCs with the results of time‐conversion studies for copolymerization of monomers in the presence of different concentrations of blowing agent. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Decoy Technology as a Promising Therapeutic Tool for Atherosclerosis

Cardiovascular diseases (CVDs) have been classified into several types of disease, of which atherosclerosis is the most prevalent. Atherosclerosis is characterized as an inflammatory chronic disease which is caused by the formation of lesions in the arterial wall. Subsequently, lesion progression and disruption ultimately lead to heart disease and stroke. The development of atherosclerosis is the underlying cause of approximately 50% of all deaths in westernized societies. Countless studies have aimed to improve therapeutic approaches for atherosclerosis treatment; however, it remains high on the global list of challenges toward healthy and long lives. Some patients with familial hypercholesterolemia could not get intended LDL-C goals even with high doses of traditional therapies such as statins, with many of them being unable to tolerate statins because of the harsh side effects. Furthermore, even in patients achieving target LDL-C levels, the residual risk of traditional therapies is still significant thus highlighting the necessity of ongoing research for more effective therapeutic approaches with minimal side effects. Decoy-based drug candidates represent an opportunity to inhibit regulatory pathways that promote atherosclerosis. In this review, the potential roles of decoys in the treatment of atherosclerosis were described based on the in vitro and in vivo findings.