An improved bat optimization algorithm to solve the tasks scheduling problem in open shop

Neural Computing and Applications - The open shop scheduling problem involves a set of activities that should be run on a limited set of machines. The purpose of scheduling open shops problem is to...     

Approximation and inapproximability results for maximum clique of disc graphs in high dimensions

We prove algorithmic and hardness results for the problem of finding the largest set of a fixed diameter in the Euclidean space. In particular, we prove that if A^∗ is the largest subset of diameter r of n points in the Euclidean space, then for every ε>0 there exists a polynomial time algorithm that outputs a set B of size at least |A^∗| and of diameter at most . On the hardness side, roughly speaking, we show that unless P=NP for every ε>0 it is not possible to guarantee the diameter for B even if the algorithm is allowed to output a set of size .     

Size-dependent effects on critical flow velocity of a SWCNT conveying viscous fluid based on nonlocal strain gradient cylindrical shell model

This article investigates vibration and instability analysis of a single-walled carbon nanotube (SWCNT) conveying viscous fluid flow. For this purpose, the first-order shear deformation shell model is developed in the framework of nonlocal strain gradient theory (NSGT) for the first time. The proposed model is a conveying viscous fluid in which the external force of fluid flow is applied by the modified Navier–Stokes relation and considering slip boundary condition and Knudsen number. The NSGT can be reduced to the nonlocal elasticity theory, strain gradient theory or the classical elasticity theory by inserting their specific nonlocal parameters and material length scale parameters into the governing equations. Comparison of above-mentioned theories suggests that the NSGT predicts the greatest critical fluid flow velocity and stability region. The governing equations of motion and corresponding boundary conditions are discretized using the generalized differential quadrature method. Furthermore, the effects of the material length scale, nonlocal parameter, Winkler elastic foundation and Pasternak elastic foundation on vibration behavior and instability of a SWCNT conveying viscous fluid flow with simply supported and clamped–clamped boundary conditions are investigated.     

CFD simulation and optimization of ICEs exhaust heat recovery using different coolants and fin dimensions in heat exchanger

In this paper, finned type heat exchangers with different fin dimensions in the exhaust of a gasoline engine are modeled numerically for improving the exhaust energy recovery. RNG k-ε viscous model is used and the results are compared with available experimental data presented by Lee and Bae (Int J Therm Sci 47:468–478, 2008) where a good agreement is observed. Also, the effect of fin numbers, fin length and three water-based nanofluid coolants (TiO₂, Fe₂O₃ and CuO) on the heat recovery efficiency are investigated in different engine loads. As a main outcome, results show that increasing the fin numbers and using TiO₂-water as cold fluid are the most effective methods for heat recover. Furthermore, an optimization analysis is performed to find the best fins dimensions using response surface methodology.     

UPLC and HPLC of caffeoyl esters in wild and cultivated Arctium lappa L.

Analytical methods including ultra-performance liquid chromatography (UPLC) and high-performance liquid chromatography (HPLC) with photodiode array (PDA) detector were developed for the analysis of caffeoylquinic acid derivatives in seeds, leaves and roots of Arctium lappa L. Separation was performed on C₁₈ column utilising 5% (v/v) acetic acid in water and acetonitrile at 330 nm. Both methodologies were validated in terms of linearity, precision, and recovery. The results showed that the major advantages of UPLC, over HPLC were the fast analysis, narrow peaks, high sensitivity, and reduction of solvent consumption. Subsequently the methods were applied for the identification and quantification of chlorogenic acid (5-CQA) and 1,5-dicaffeoylquinic acid (1,5-DCQA) as main compounds in samples. The total phenolic content of samples ranged from 3.93 to 14.13 g of 5-CQA equivalent/100 g dry weight (DW). There was a significant variability from 89 to 571 mg/100 g for 5-CQA and 48 to 486 mg/100 g for 1,5-DCQA in dry material.     

Selecting human machine interface package in integrating a process automation system

In this paper we propose a framework for evaluating and selecting human machine interface (HMI) packages in integrating a process automation system. HMIs are among main subsystems of many integrated process automation systems. The main objective of this paper is to propose a selection process so that the integrated system could better satisfy strategic goals of the system users. In this paper we assume that strategic goals are expressed in terms of concepts like production flexibility, production reliability, product quality, operation cost, production time and the like.     

Comparison of MBE Growth of InSb on Si (001) and GaAs (001)

We describe the epitaxial growth of InSb films on both Si (001) and GaAs (100) substrates using molecular-beam epitaxy and discuss the structural and electrical properties of the resulting films. The complete 2 μm InSb films on GaAs (001) were grown at temperatures between 340°C and 420°C and with an Sb/In flux ratio of approximately 5 and a growth rate of 0.2 nm/s. The films were characterized in terms of background electron concentration, mobility, and x-ray rocking curve width. Our best results were for a growth temperature of 350°C, resulting in room-temperature mobility of 41,000 cm²/V s.  For the growth of InSb on Si, vicinal Si(001) substrates offcut by 4° toward (110) were used. We investigated growth temperatures between 340°C and 430°C for growth on Si(001). In contrast to growth on GaAs, the best results were achieved at the high end of the range of T _S =  C, resulting in a mobility of 26,100 cm²/V s for a 2 μm film. We also studied the growth and properties of InSb:Mn films on GaAs with Mn content below 1%. Our results showed the presence of ferromagnetic ordering in the samples, opening a new direction in the diluted magnetic semiconductors.     

Thermal behavior of longitudinal convective–radiative porous fins with different section shapes and ceramic materials (SiC and Si3N4)

In this study, heat transfer and temperature distribution equations for longitudinal convective–radiative porous fins are presented. It is assumed that the thickness of fins varies with length, so four different shapes (rectangular, convex, triangular and exponential) are considered. Temperature-dependent heat generation, convection and radiation are considered and heat transfer through porous media is simulated using passage velocity from Darcy's model. After deriving equation for all geometries, the Least Square Method (LSM) and fourth order Runge–Kutta method (NUM) are applied for predicting the temperature distribution in the porous fins. The selected ceramic porous materials are Al, SiC, and Si₃N₄. Effects of porosity, Darcy number, Rayleigh number, etc. on transferred heat are examined. As a main outcome, exponential section fin with Si₃N₄ material has the most amount of transferred heat among other shapes and materials.     

KDB: a fast update and high speed packet classifier in SDN

The Journal of Supercomputing - Packet classification is a fundamental function to support several services of software defined networking (SDN). Increasing complexity of the flow tables in SDN...