Solving the heterogeneous fixed fleet open vehicle routing problem by a combined metaheuristic algorithm

The vehicle routing problem (VRP) is a well-known combinatorial optimisation problem and holds a central place in logistics management. Many exact, heuristic and metaheuristic approaches have been proposed to solve VRP. An important variant of the VRP arises when a ?eet of vehicles is fixed and characterised by different capacities for distribution activities. The problem is known as the heterogeneous fixed fleet VRP (HFFVRP). The HFFVRP is a natural generalisation of the VRP with several vehicle types, each type being defined by a capacity, a fixed cost and a cost per distance unit, and can cover more practical situations in transportation. This problem consists of determining a set of vehicle trips of minimum total length in which a set of customers is to be satisfied in the demand constraints using identical vehicles with limited capacity. If open routes instead of closed ones are considered in the HFFVRP, the problem becomes a heterogeneous fixed fleet Open VRP (HFFOVRP) which has numerous applications in industrial and service problems. In this paper, a bone route algorithm which uses the tabu search as an improved procedure is utilised to solve the HFFOVRP. The proposed algorithm was tested empirically on a 24 of generated VRPs, and compared with elite ant system and ant colony system. In all cases, the proposed algorithm finds the best-known solutions within a reasonable time.     

The Kinetic of Dust with Different Sizes in a Magnetized Collisional Plasma Sheath

The characteristics of dust are investigated in a magnetized plasma sheath with taking into account the gravitational force and collisions between dust and neutral. The model is based on using fluid method and solving the basic equations of fluid method numerically. As the Lorentz, gravitational and collisional forces depend on the dust radius, the numerical calculations are done for different values of dust radius. It enables us to study the effects of dust size on dust dynamics in a magnetized plasma sheath.     

An efficient binary chaotic symbiotic organisms search algorithm approaches for feature selection problems

The Journal of Supercomputing - Feature selection is one of the main steps in preprocessing data in machine learning, and its goal is to reduce features by removing additional and noisy features....     

Investigation of the ConXL moment connection cyclic behavior in box columns without filling concrete with different arrangement of collar bolts

The aim of this study was to study numerically the seismic behavior of ConXL connection without filler concrete of columns and reduce the number of collar bolts with different arrangement. For this purpose, to verify the modeling and analyzing, we compared the numerical results of specimens (reduced beam section, end plate and Kaiser bolted bracket (KBB) connections) with the experimental results and observed a good agreement. Afterward, 18 specimens of ConXL moment connections in box columns not filled with concrete with axial force in single, planar and bi‐axial loading conditions with different arrangement of bolts were studied, and their performances were evaluated. Results show that seismic behavior of specimens with beam section depth less than W30 series under cyclic loading, even with reduces of number of bolts to 16 numbers, are suitable in the over 0.04 rad rotations. In addition, the use of 16 bolts in W30 series beams connections is suitable provided they are used in the corner connections (with single sided loading) and the material specifications ASTM‐A36 are used for the beams. Moreover, the closer the position of bolts related to the outer side of collar flange, the more axial strain of bolts shank and the lesser slippage. The most optimum of bolt position is the surface middle of the collar flange and collar corner. Copyright © 2014 John Wiley & Sons, Ltd.     

A simple quantitative approach for post earthquake damage assessment of flexure dominant reinforced concrete bridges

Conventional methods for displacement based condition assessment of bridges solely rely on the maximum level of displacements experienced by the piers, and do not take into account the accumulated damage that result from cyclic loading. More advanced approaches take this into account by considering the structural damage as a linear combination of the normalized maximum displacements and hysteretic energy. Computation of the dissipated hysteretic energy requires monitoring of the lateral forces during the seismic events, which are not as practical as monitoring bridge pier deformations. This article reports on the development of a simple damage assessment method that considers the effect of cyclic loading on the state of damage and it is merely based on monitoring the bridge pier deformations. A fiber optic displacement serial array was designed for measuring the crack opening displacement reversals at the plastic hinge areas.     

Numerical study of heat transfer enhancement using perforated dual twisted tape inserts in converging‐diverging tubes

In this article, a 3D numerical simulation for investigating friction factor and heat transfer enhancements in case of inserting normal or perforated dual twisted tapes (TTs) in converging‐diverging tubes (CDTs) is presented. The effects of Reynolds number changing from 10,000 to 20,000 and a various number of holes (N = 0, 1, 2, and 3) in TTs, under constant uniform heat flux on tube outer wall and using water as working fluid circumstances, were examined. It was found that generally using dual TTs in CDTs improves the Nusselt number up to 9% compared to bare CDTs. Perforating TTs do not have a noticeable effect on heat transfer, but decrease the friction factor significantly, up to 396% compared to normal dual TT implantation, in higher Reynolds numbers. Following that, thermal performance factor considerably increases up to 57%, compared to CDTs with normal dual TTs. To show the mechanism of these effects, velocity streamlines are presented and will be discussed in this paper.     

Central composite design for the optimization of supercritical carbon dioxide fluid extraction of fatty acids from Borago officinalis L. flower

Abstract: In the present study, fatty acids and essential oils of the flower of borage (Borago officinalis L.) were obtained by supercritical carbon dioxide fluid extraction under different conditions. The extracts obtained were compared to oils of borage flower oil isolated by hydrodistillation. The obtained oils were analyzed by gas chromatography mass spectrometry. The compounds were identified according to their retention indices and mass spectra. The experimental parameters of supercritical fluid extraction (SFE) were optimized using a central composite design after a full factorial experimental design. Extraction yields based on SFE varied in the range of 0.02% to 1.96% (w/w), and the oil yield based on the hydrodistillation was 0.05% (v/w). The optimum conditions of SFE were obtained at a pressure of 350 atm, a temperature of 65 °C, a methanol modifier volume of 100 μL, and static and dynamic extraction time of 10 min. Main components of the extracts under optimum SFE conditions were palmitic acid, linoleic acid, γ‐linolenic acid, and oleic acid. The results indicated that by using the suitable extraction conditions, SFE is more effective than the conventional hydrodistillation method in the extraction of fatty acids and the preservation of its quality. Practical Application: SFE is a good technique for the extraction of oils from plants. The extraction yields by SFE are more than the conventional method. SFE is used on a large scale for production of essential oils and pharmaceutical products from plants.     

Application of global optimization strategies to refinery hydrogen network

In this paper, a new method is presented in optimization of hydrogen network. The mixed integer non-linear programming (MINLP) and non-linear programming (NLP) problems have been solved with two methods, simultaneously. The linearization technique for non-linear programming models which proposed by McCormick (1976) and also a new method proposed by Faria and Bagajewicz (2011) have been used to solve these problems. Application of this new method is presented in global optimization of MINLP/NLP, and hydrogen network problem.