Solving constrained optimisation problems using the improved imperialist competitive algorithm and Deb’s technique

ABSTRACT

In this paper, an improved imperialist competitive algorithm called I-ICA is proposed for solving constrained optimisation problems. In I-ICA, the use of differential evolution (DE)/rand/1 mutation operator at assimilation step enhances the population diversity. Also, the binomial crossover operator improves the speed of convergence to optimal solution by distributing good information among solutions. Furthermore, Deb’s rules were applied for handling constrains. Examinations were done on 24 well-known functions and 5 engineering design problems. The comparison of I-ICA with basic ICA and 22 state-of-the-art algorithms shows I-ICA’s superiority in terms of the rate of convergence and quality of the obtained solution.     

Production of active lipase by Rhizopus oryzae from sugarcane bagasse: solid state fermentation in a tray bioreactor

This study deals with production of lipase in solid state fermentation by Rhizopus oryzae from sugarcane bagasse. A tray bioreactor was designed for the extracellular enzyme production. Daily, lipase production was evaluated at several incubation temperatures. Furthermore, the influence of temperature and humidity of the cabinet, depth of solid bed, particle size, initial moisture content and supplementary substrate (olive oil) as carbon source was investigated. The obtained results showed that bioreactor temperature of 45 °C, humidity of 80%, solid bed depth of 0.5 cm, particle size in the range of 0.335–1 mm, substrate initial moisture content of 80% for the top tray and 70% for the middle tray and supplementary substrate of 8% (v/w) olive oil led to maximum lipase production. Under optimum fermentation conditions after 72‐h incubation, maximum lipase activities for the top, middle and bottom trays were 215.16, 199.36 and 52.64 U gds^?1, respectively.     

Thermodynamic Analysis of Propane Aromatization

Chemical equilibria of propane aromatization under both unrestricted coke-formation and coke-free operating conditions were studied. In both cases, propane conversions were nearly complete. The aromatics selectivity was observed to be 46% at a temperature of 823 K (1 bar) under coke-free operating conditions. Application of hydrogen and steam as coke-removing agents was also studied. Under coke-free operation, the presence of low level of water in the feed favors propane methanation, whereas higher levels of water enhance propane steam reforming. Methane selectivity was found to attain a maximum at H₂O/C₃H₈ molar ratio equal to 0.75 (823 K, 1 bar). The outcomes of the present study imply that the products selectivity has to be controlled kinetically and that the catalyst formulation should be aimed at minimization of coke formation and carbon-carbon bond breakage activity.     

The influence of surface chemistry of nano-silica on microstructure,optical and mechanical properties of the nano-silica containing clear-coats

Different nano-silicas were incorporated in an automotive OEM clear-coat based on acrylic-melamine chemistry. The morphological characteristics of the heat-cured films were investigated using scanning electron microscopy. It was found that there is a close relationship between the interfacial interactions of binder-silica nano-particles and mechanical and optical properties of the baked films.     

Inventory lot-sizing with supplier selection using hybrid intelligent algorithm

In supply chain management (SCM), multi-product and multi-period models are usually used to select the suppliers. In the real world of SCM, however, there are normally several echelons which need to be integrated into inventory management. This paper presents a hybrid intelligent algorithm, based on the push SCM, which uses a fuzzy neural network and a genetic algorithm to forecast the rate of demand, determine the material planning and select the optimal supplier. We test the proposed algorithm in a case study conducted in Iran.     

Thermal and mechanical properties of polyurethane rigid foam/modified nanosilica composite

Surface modification of fumed nanosilica was performed by using n‐(2‐aminoethyl)‐3‐aminopropyltrimethoxysilane as a coupling agent. Then, modified nanosilica was utilized in the preparation of polyurethane rigid foam. The characterization and the study of properties were done by some techniques, such as Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, dynamic mechanical analysis, and thermomechanical analysis. Also, tensile test was examined to evaluate the static mechanical properties. With the increasing of modified nanosilica, thermal and static mechanical properties were enhanced, but dynamic mechanical behavior was different from static mechanical behavior because of the different properties of interfacial domain and bulk matrix. The presence of functional groups on the nanosilica surface affected stoichiometry and reduced hard phase formation in bulk polymer. The decrease in glass transition temperature (T_g) confirmed this statement. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

Characteristics and Composition of Watermelon Seed Oil and Solvent Extraction Parameters Effects

Watermelon seed oil characteristics were evaluated to determine whether this oil could be exploited as an edible oil. Hexane extraction of watermelon seeds produced yields of 50% (w/w) oil. The refractive index, saponification and iodine value were 1.4712 (at 25 °C), 200 mg KOH/g and 156 g I/100 g, respectively. The acid and peroxide values were 2.4 mg KOH/g and 3.24 mequiv/kg, respectively. The induction time of the oil was also 5.14 h at 110 °C, which was measured for the first time. Total unsaturation contents of the oil was 81.6%, with linoleic acid (18:2) being the dominant fatty acid (68.3%). Considering that the watermelon seed oil was highly unsaturated, the relatively high induction time might indicate the presence of natural antioxidants. In addition, the influence of extraction parameters on extraction of oil from watermelon seed with hexane as a solvent was studied at several temperatures (40, 50, and 60 °C), times (1, 2, and 3 h) and solvent/kernel ratios (1:1, 2:1, and 3:1). The oil yield was primarily affected by the solvent/kernel ratio and then time and temperature, respectively. The protein content of the oil-free residue was 47%.     

Design of electronic sections for nano-displacement measuring system

Noncontact displacement measurement is generally based on the interferometry method.In the semiconductor industry,a technique for measuring small features is required as circuit integration becomes denser and the wafer size becomes larger.An interferometric system known as a three-longitudinal-mode heterodyne interferometer (TLMI) is made of two main parts:optical setup and electronic sections.In the optical part,the base and measurement signals having 500-MHz frequency are produced,resulting from interfering three longitudinal modes.The secondary beat frequency to measure the displacement in the TLMI is about 300kHz.To extract the secondary beat frequency,wide-band amplifiers,double-balanced mixers (DBMs),band-pass filters (BPFs),and low-pass filters (LPFs) are used.In this paper,we design the integrated circuit of a super-heterodyne interferometer with total gain of 56.9dB in size of 1030μm×1030μm.     

Band structure effect on the electron current oscillation in ultra-scaled GaSb Schottky MOSFET: tight-binding approach

This paper explores band structure effect on the quantum transport of a low-dimensional GaSb Schottky MOSFET (SBFET) for the implementation of III–V transistor with a low series resistance. Precise treatment of the full band structure is employed applying sp ³ d ⁵ s ^? tight-binding (TB) formalism. A remarkable distinction between the thickness dependent effective masses extracted from the TB and the bulk values imply that the quantum confinement modifies the device performance. Strong transverse confinement leads to the effective Schottky barrier height increment. Owing to the adequate enhanced Schottky barriers at low drain voltages, a double barrier gate modulated potential well is formed along the channel. The double barrier profile creates a longitudinal quantum confinement and induces drain current oscillation at low temperatures. Significant factors that may affect the current oscillation are thoroughly investigated. Current oscillation is gradually smoothed out as the gate length shrinks down in ultra scaled structure. The results in this paper are paving a way to clarify the feasibility of this device in nanoscale regime.