Analysis of the Influence of Element’s Entropy on the Bulk Metallic Glass (BMG) Entropy,Complexity, and Strength

Metallurgical and Materials Transactions A - Bulk metallic glasses (BMGs) are disordered compounds without a long-range crystalline order. In this paper, we study the effect of an element’s...     

Optimal design of support parameters for minimum force transmissibility of a flexible rotor based on H∞ and H2 optimization methods

Rotating machinery support design with the aim of reducing the force transmitted to the foundation has significant importance regarding the various applications of this machinery. This article presents H_∞ and H₂ methods for calculating the optimum support flexibility and damping of flexible rotors to minimize force transmissibility in the vicinity of the rotor’s first critical speed. First, the governing equations for the Jeffcott rotor model mounted on flexible supports are derived and the optimal parameters for the supports are analytically achieved by H_∞ and H₂ optimization procedures. The proposed approach of the tuned damper support system is similar to that designed for dynamic vibration absorber optimization. The main objective of the H_∞ optimization is to minimize the force transmitted based on fixed-point theory and the mean square transmissibility of flexible rotor is minimized in the H₂ optimization design as analytical formulae. It is proven by numerical solution that the system optimization design can effectively minimize the force transmitted to the foundation. Comparison of two optimization than with H_∞.     

ANFIS modeling of carbon dioxide capture from gas stream emissions in the petrochemical production units

Amino acid salt, especially sodium glycinate, was known as a new class of environment-friendly solution that is now being studied as a favorable alternative to amines. In the present collaboration, the Adaptive Network-based Fuzzy Inference System (ANFIS) was employed to estimate CO₂ loading capacity in the presence of aqueous sodium glycinate solution under broad ranges of temperature and pressure. The outcomes of suggested ANFIS model indicated their brilliant agreement with corresponding experimental values. The calculated values of mean relative error and R-squared were 2.93 and 0.988, respectively. Our suggested model can be of huge value for process engineers to have a simple and accurate tool in order to have rapid estimations of CO₂ solubility as a function of temperature, pressure, and mass composition of sodium glycinate solution.     

An experimental study on electrical effect on asphaltene deposition

Asphaltene generally existed in colloidal form in cruds and will precipitate in non-equilibrium conditions. Asphaltene instability may take place in the reservoir leading to permeability damage and contributing to flow restriction issues. It may also occur in production strings and surface facilities causing pipe blockage. Any change in oil composition or pressure and temperature at any stage of production will destabilize crude oil producing asphaltene precipitation. In this paper, the stability of target crude oil under the influence of a direct current and contacting with polar fluid, water, is investigated. The amount of the asphaltene deposit and its electrical charge at various operating conditions are investigated. The fact that deposits form on the anode surface proves that asphaltene particles possess a positive charge. The amounts of asphaltenes precipitation were increased considerably by increasing water as polar component.     

Optimization of sewer networks using the mixed-integer linear programming

This paper introduces a method for optimizing sewer networks using the mixed-integer linear programming (MILP) for a given layout. The objective function is defined as the sum of the costs for pipe purchase, pipe-laying, and manhole construction expressed in linear terms and subject to minimum and maximum allowable slopes, velocities, and relative depths for both minimum and maximum sewage discharge rates in each pipe. Additionally, provisions are made as constraints or conditions to ensure that a minimum pipe cover is required, that pipe diameters do not decrease in the flow direction, and that pipes maintain a steady elevation at each manhole. All the non-linear constraints are transformed into the linear format. Pipe slope, binary variables accounting for commercial pipe diameters and average implemented depths have also been considered as decision variables. Finally, the performance of the proposed optimization method is evaluated in a benchmark sewer network from the literature.     

A robust spread spectrum based image watermarking in ridgelet domain

A new robust method of spread spectrum based image watermarking is proposed in this article. Spread spectrum technique and scrambling are used for increasing robustness and invisibility of the algorithm. Our suggested method is carried out using ridgelet transform as an efficient transform for representing images with line singularities. In embedding part, the host image is partitioned into non-overlapping blocks and ridgelet transform is applied to each single block. In this way, a curved edge is divided into some straight edges so that ridgelet transform shows optimal performance even for complicated images with curve edges. To embed the watermark bits, the best directions of ridgelet coefficients are selected with respect to their variance intensity. In extraction part, a computationally efficient detection method is used for detecting watermark logo blindly from distorted watermarked image. To achieve more robust algorithm firstly, we find the best place to insert the watermark bits and secondly, we encode the scrambled watermark bits by pseudo random sequences with an authentication key. Robustness of our proposed method is tested against different kinds of attacks. According to the experimental results, proposed method shows much improved performance in comparison to other published works.     

Blind per tone equalization of multilevel signals using support vector machines for OFDM in wireless communication

We present an efficient support vector machine (SVM)-based blind per tone equalization for OFDM systems. Blind per tone equalization using constant modulus algorithm (CMA) and multi-modulus algorithm (MMA) are used as the comparison benchmark. The SVM-based cost function utilizes a CMA-like error function and the solution is obtained by means of an iterative re-weighted least squares algorithm (IRWLS). Moreover, like CMA, the error function allows to extend the method to multilevel modulations. In terms of bit error rate (BER), simulation experiments show that the blind per tone equalization using SVM performs better than blind per tone equalization using CMA and MMA.     

Binary mixtures of fatty alcohols and fatty acid esters as novel solid‐liquid phase change materials

The discovery of new eutectic phase change materials (PCMs) will overcome the current PCM challenges such as nonbiodegradability, super‐cooling, and limited thermal stability. This paper reports on the development of new bio‐based PCMs composed of binary mixtures of fatty acid esters and fatty alcohols at their eutectic compositions, which provide potential solid‐liquid PCMs for building applications. Six binary systems, namely 1‐dodecanol (DD) + methyl stearate (MES), DD + methyl palmitate (MEP), DD + methyl laurate (MEL), 1‐tetradecanol (TD) + MES, TD + MEP, and TD + MEL were prepared and their thermal behaviours were deliberated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), long‐term thermal stability test, and mass loss analysis. Amongst the studied systems, phase change transition temperature and latent heat of fusion of the eutectic mixtures of DD‐MES, DD‐MEP, TD‐MES, and TD‐MEP were found to be suitable for the building application with values of 22.46°C/201.91 J/g, 20.34°C/224.45 J/g, 32.05°C/209.38 J/g, and 26.72°C/210.15 J/g, respectively. The average degree of super‐cooling for all PCMs was below 2°C, and no significant changes in thermophysical properties of the developed PCMs were observed after 1000 thermal cycles.