A novel method of S-box design based on discrete chaotic maps and cuckoo search algorithm

Multimedia Tools and Applications - Substitution-boxes (S-boxes) are unique nonlinear elements, which are used to achieve the property of confusion in modern symmetric ciphers and offer resistance...     

Nanoscale Defect Engineering and the Resulting Effects on Domain Wall Dynamics in Ferroelectric Thin Films

Defect engineering is one of the cornerstones of the modern electronics industry. Almost all electronic devices include materials that have been doped by ion bombardment. For materials where crystallinity is essential, such as ferroelectrics, defect type and concentration can vastly influence properties and are often used to optimize device performance. This study shows a method to effectively control the density and position on the nanoscale of defect sites in thin films of Pb(Zr,Ti)O₃ via focused ion beam microscopy. This allows for exceptional clarity of observation of the role of defects in nucleation, polarization switching, and domain wall interaction through investigation with piezoresponse force microscopy and transmission electron microscopy, adding insight to accepted but seldom‐demonstrated facts on defect‐induced effects. This nanoscale defect engineering can be used as a tool to control material properties, and furthermore, a route is demonstrated toward a practical application.     

Independent dimension-weighting mechanisms for visual selection and stimulus identification.

Observers respond faster when the task-relevant perceptual dimension (e.g., color) repeats across consecutive trials relative to when it changes. Such dimension repetition benefits (DRBs) occur in different tasks, from singleton feature search to feature discrimination of a stimulus presented on its own. Here, we argue that the DRBs observed in different tasks originate from distinct mechanisms: preselective weighting of dimension-specific feature contrast signals and, respectively, postselective stimulus processing. The multiple-weighting-systems hypothesis predicts significant DRBs across trials of different tasks that share the same weighting mechanism, but not across tasks involving different mechanisms. Experiments 1, 2, and 3 examined DRBs across localization and detection tasks (both involving feature contrast computations); across detection and identification tasks (which presumably involved different weighting systems); and across identification and discrimination tasks (both involving stimulus identification). As expected, significant DRBs were observed across different tasks in Experiments 1 and 3, but not in Experiment 2. These findings support the multiple-weighting-systems hypothesis. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Decolorization of reactive textile dyes using water falling film dielectric barrier discharge

Decolorization of reactive textile dyes Reactive Black 5, Reactive Blue 52, Reactive Yellow 125 and Reactive Green 15 was studied using advanced oxidation processes (AOPs) in a non-thermal plasma reactor, based on coaxial water falling film dielectric barrier discharge (DBD). Used initial dye concentrations in the solution were 40.0 and 80.0 mg/L. The effects of different initial pH of dye solutions, and addition of homogeneous catalysts (H₂O₂, Fe²⁺ and Cu²⁺) on the decolorization during subsequent recirculation of dye solution through the DBD reactor, i.e. applied energy density (45-315 kJ/L) were studied. Influence of residence time was investigated over a period of 24 h. Change of pH values and effect of pH adjustments of dye solution after each recirculation on the decolorization was also tested. It was found that the initial pH of dye solutions and pH adjustments of dye solution after each recirculation did not influence the decolorization. The most effective decolorization of 97% was obtained with addition of 10 mM H₂O₂ in a system of 80.0 mg/L Reactive Black 5 with applied energy density of 45 kJ/L, after residence time of 24 h from plasma treatment. Toxicity was evaluated using the brine shrimp Artemia salina as a test organism.     

Frequency domain boundary element versus time domain finite element model for the transient analysis of horizontal grounding electrode

The paper deals with two different approaches to the assessment of the transient impedance of a horizontal grounding electrode: frequency domain boundary element analysis, based on the straight thin wire antenna model (AM) and generalized telegrapher’s equations combined with inverse Fast Fourier Transform (FFT); and time domain finite element analysis based on the transmission line model (TLM) and standard telegrapher’s equations. Extensive numerical experiments have been undertaken and some of illustrative numerical results are presented in this paper.     

Thermodynamic analysis and characterization of Bi–Cu–Sn alloys as advanced lead-free solder materials for high temperature application

Due to the frequent use of Cu as a substrate material in electronics, it is important to understand the interactions between the solders and the substrates, based on the knowledge of the phase equilibria, thermodynamics and other characteristics of the Bi–Cu–Sn system. The results of thermodynamic analysis and characterization of Bi–Cu–Sn alloys as advanced lead-free solder materials for high temperature application are presented in this paper. The research includes analytical investigations done by thermodynamic predicting according to general solution model in temperature range 1,073–1,273 K and experimental investigations performed by differential thermal analysis, differential scanning calorimetry, optical microscopy, hardness and electroconductivity measurements for the sections with molar ratio Bi:Cu = 1:1, 1:3 and 3:1.     

Multimodal spectral imaging of cells using a transmission diffraction grating on a light microscope

A multimodal methodology for spectral imaging of cells is presented. The spectral imaging setup uses a transmission diffraction grating on a light microscope to concurrently record spectral images of cells and cellular organelles by fluorescence, darkfield, brightfield, and differential interference contrast (DIC) spectral microscopy. Initially, the setup was applied for fluorescence spectral imaging of yeast and mammalian cells labeled with multiple fluorophores. Fluorescence signals originating from fluorescently labeled biomolecules in cells were collected through triple or single filter cubes, separated by the grating, and imaged using a charge-coupled device (CCD) camera. Cellular components such as nuclei, cytoskeleton, and mitochondria were spatially separated by the fluorescence spectra of the fluorophores present in them, providing detailed multi-colored spectral images of cells. Additionally, the grating-based spectral microscope enabled measurement of scattering and absorption spectra of unlabeled cells and stained tissue sections using darkfield and brightfield or DIC spectral microscopy, respectively. The presented spectral imaging methodology provides a readily affordable approach for multimodal spectral characterization of biological cells and other specimens.     

Optimal cascade hydraulic control for a parallel robot platform by PSO

A new cascade load force control design for a parallel robot platform is proposed. A parameter search for a proposed cascade controller is difficult because there is no methodology to set the parameters and the search space is broad. A parameter search based on particle swarm optimization (PSO) is suggested to effectively search the parameters of the cascade controller. We used a unified mathematical model of a hydraulic actuator of parallel robot platform. These equations are readily applicable to various types of proportional valves, and they unify the cases of critical center, overlapped, and underlapped valves. These unified model equations are useful for nonlinear controller design. Simulation results show the advantages of the proposed optimal tuned cascade controller to solve the formulated tracking problem in relation to the classical proportional–integral (PI) controller.