Dynamic switching characteristic dependence on sidewall angle for phase change memory

In this paper, the volume-minimized model of phase change memory (PCM) cell with Ge₂Sb₂Te₅ (GST) material has been established to study the dynamic switching (set-to-reset) characteristic dependence on the sidewall angle. Joule heating volume, threshold current, dynamic resistance and phase transition rate of PCM cells by current pulse are all calculated. The results show that the threshold current increases with decreasing the sidewall angle and is significantly impacted by the feature size and aspect ratio. The PCM cell of 90° sidewall angle exhibits the smallest Joule heating volume, the highest RESET resistance and the fastest phase transition property.     

Computation Controllable Mode Decision and Motion Estimation for Scalable Video Coding

This paper proposes an efficient computation‐aware mode decision and search point (SP) allocation algorithm for spatial and quality scalabilities in Scalable Video Coding. In our proposal, a linear model is derived to allocate the computation for macroblocks in enhancement layers by using the rate distortion costs of the base layer. In addition, an adaptive SP decision algorithm is proposed to decide the number of SPs for motion estimation under the constraint of the allocated computation. Experiment results demonstrate that the proposed algorithm allocates the computation resource efficiently and outperforms other works in rate distortion performance under the same computational availability constraint.     

Experimental study of the relationship between separation performance and lengths of vortex finder of a novel de-foulant hydrocyclone with continuous underflow and reflux function

To solve the blockage and defer the fouling of sewage heat exchanger, a novel de-foulant hydrocyclone with continuous underflow and reflux function was proposed. Experimental results demonstrated that the novel hydrocyclone had a remarkable behavior on separating the sand (75–250 μm) and foulant (<4 mm). The continuous underflow and reflux function could significantly improve the separation efficiency by relieving the particle re-entrainment and eliminating the air core without increasing energy consumption (<17 kPa) and split ratio (<10%) considerably. Besides, the range of optimum vortex finder length was proportional to the particle density.     

A study of JP-8 surrogate coflow flame structure by combined use of laser diagnostics and numerical simulation

The structure of a JP-8 coflow flame is investigated by applying laser diagnostic techniques to three different fuel surrogates. The results are compared against theoretical predictions from numerical simulations; very good agreement is obtained for temperature and major species.Rayleigh and Raman scattering are used to measure temperature and major species mole fractions in the flame (oxygen, carbon dioxide, water, and fuel molecules). Quantitative laser diagnostic techniques are particularly challenging when applied to jet-fuel flames; the presence of aromatic molecules in the fuel mixtures and the formation of polyaromatic compounds inside the flame generate spectrally broad fluorescence signals that interfere with the measurement. A polarized/depolarized subtraction technique combined with a post-processing filter based on least-squares fitting is used to mitigate this undesired effect. The proposed technique tries to match the experimental signal against previously calculated spectra and has proved to be a very efficient filter at rejecting polyaromatic fluorescence.Numerical simulations play a fundamental role in this study. Computer predictions are used not only to compare experimental data, but as an active component of the data post-processing. For example, numerically calculated cross-section maps are used to refine the measured temperature for both the Rayleigh and Raman experiments.     

Comparison study on different ITM‐integrated MCFC hybrid systems with CO2 recovery using sweep gas

Previous study shows the ITM (oxygen ion transfer membrane)‐integrated MCFC (molten carbonate fuel cell) hybrid system with CO₂ recovery can maintain high efficiency; however, the oxygen partial pressure on the ITM permeate side is usually 1 atm, which requires a very high pressure ratio of the ITM air compressor in order to separate the oxygen; using the sweep gas can solve this problem. In this paper the ITM‐integrated MCFC hybrid systems with CO₂ recovery using different sweep gases are studied. With the Aspen plus software, two systems with different sweep gases are established, and their performances are compared with the benchmark system without sweep gas; the effects of key parameters on the optimum system performance are also investigated. Results show that compared with the benchmark system, the efficiencies of the systems with sweep gases are increased and the pressure ratios of the air compressors are decreased; the system using pure CO₂ as sweep gas can improve the system efficiency by 1.25%, which is superior to the system using the mixture gas of CO₂ and H₂O as sweep gas. Achievements from this paper will provide a valuable reference for CO₂ recovery from the MCFC hybrid power system with lower energy consumption. Copyright © 2016 John Wiley & Sons, Ltd.     

Dynamic mechanical behavior of mPE/mEP blends: experimental and prediction

Metallocene-catalyzed polyethylene (mPE)/metallocene-catalyzed ethylene–propylene copolymer (mEP) blends were prepared with a mixing apparatus. The morphology of the blends was observed by scanning electron microscopy and the dynamic mechanical behavior of the blends was systematically investigated. Mean-field theories developed by Kerner were applied to these binary blends of different compositions. The Kerner’s model calculations were compared with the experimental dynamic mechanical properties of the blends and their morphological characterizations. The results showed that Kerner’s model can reasonably predict the viscoelasticity of mPE/mEP blends with different compositions. In addition, the morphological structure of the blends can be estimated via comparing the predicted dynamic mechanical behavior with the experimental data.     

Effects of 3d Transition Metal Elements in the B2-FeAl Structure

Based on the Chen–M?bius lattice inversion and a series of pseudopotential total energy curves, a parameter-free method was used to derive Fe(Al)-X (where X = Co, Cr, Cu, Mn, Ni, Sc, Ti, V, and Zn) interatomic potentials to study the effects of 3d transition metal elements substituting Fe or Al atoms in the B2-FeAl structure. Through molecular dynamics, the site preference of each type of defect was determined by comparing total energy calculations. The changes in lattice parameters and bulk modulus associated with the presence of defects in the FeAl matrix were also studied. The results are compared, when available, with experimental data and other theoretical results.     

Multiple-optima search method based on a metamodel and mathematical morphology

This article investigates a non-population-based optimization method using mathematical morphology and the radial basis function (RBF) for multimodal computationally intensive functions. To obtain several feasible solutions, mathematical morphology is employed to search promising regions. Sequential quadratic programming is used to exploit the possible areas to determine the exact positions of the potential optima. To relieve the computational burden, metamodelling techniques are employed. The RBF metamodel in different iterations varies considerably so that the positions of potential optima are moving during optimization. To find the pair of correlative potential optima between the latest two iterations, a tolerance is presented. Furthermore, to ensure that all the output minima are the global or local optima, an optimality judgement criterion is introduced.