Multiobjective car relocation problem in one-way carsharing system

Railway Engineering Science - In this paper, we present a multiobjective approach for solving the one-way car relocation problem. We fix three objectives that include the number of remaining...     

Stripping methods studies for HVOF WC-10Co-4Cr coating removal

The use of high-velocity oxyfuel (HVOF) cermet coatings is considered to be a valuable and innovative alternative technology to replace Cr(VI) electroplating. Among others, a WC-10Co-4Cr coating is one of the best choices for landing gear components due to its excellent tribology and corrosion properties. The stripping process of such a cermet coating was studied due to its importance for the repair and overhaul of landing gear components. Stripping solutions fulfill the following criteria: keep substrate integrity; exhibit a high strip rate (SR); lead to uniform dissolution; show no galvanic corrosion; and be environmentally friendly. Three different high-strength steel substrates (4340, 300M, and Aermet100) were studied. Five different stripping solutions were selected for the electrochemical study. Only three met the targeted criteria: the meta-nitrobenzane sulfonate-sodium cyanide solution; the Rochelle salt; and a commercial nickel stripper. It was found that the process must be electrolytic, and that ultrasonic agitation is needed to enhance the overall mass transport and removal of WC particles and metallic matrix residues. When choosing the most efficient solution and conditions, the SR was found to be as high as 162 μm h⁻¹, which is a very acceptable SR for productivity sake.     

Enka Hijyen：快速发展的土耳其纸尿裤生产商

Enka Hijyen公司是土耳其一家新进入婴儿纸尿裤行业的生产商,其业务预计将在近期加速增长,目标是在未来几年能够满足本地和区域市场的需求。Enka Hijyen的母公司Imam Kayali控股集团成立于1928年。开始是一家出售汽车零件的小型父子商店,如今已实现指数式增长,扩大为拥有700多名员工的集团公司。ImamKayali控股集团在评估了不断变化的婴儿纸尿裤市场的复杂性和盈利空间后,于2016年第1季度开始涉足纸尿裤行业。     

Analysis of cylindrical transmission lines with thefinite-difference time-domain method

In this paper, the finite-difference time-domain (FDTD) method is used to calculate the propagation characteristics of cylindrical transmission lines. An efficient two-dimensional FDTD algorithm is developed by projecting the three-dimensional FDTD cell in the cylindrical coordinates onto the r-φ plane. An effective absorbing boundary condition is employed to truncate the mesh at its outer radial boundary. Numerical results are derived for different cylindrical transmission lines and compared to data available in the literature. Specifically, the newly proposed cylindrical coplanar waveguide is studied both theoretically and experimentally     

A two-permeability approach for assessing flow properties in metal foam

One of the key properties for understanding the fluid flow and pressure drop in metal foam is the permeability. This paper investigates a non-traditional approach for evaluating this critical transport property by considering the physics of energy dissipation, i.e., the viscous dissipation and form drag and the fact that they are linked. The current work emphasizes the necessary initial step of clearly distinguishing between different flow regimes prior to evaluating the permeability. This distinction is usually either absent or overlooked in several previous studies, which may lead to significant errors. The approach presented in this study is applied to wind-tunnel steady-state unidirectional pressure-drop measurements for airflow through isotropic open-cell aluminum foam samples having different pore densities. The results show that the porous medium exhibits two different permeabilities—one is calculated and only valid in the Darcy regime, while the other is calculated and only valid in the Forchheimer regime.     

DELAYED COKING OF HYDROTREATED REDUCED CRUDE

ABSTRACT

A laboratory coking unit was designed and constructed for an experimental study of the delayed coking process of hydrotreated Kirkuk reduced crude. The yield and analysis of coke, gases and liquid products were obtained for each experiment. The gas < C₄. and gasoline yield decrease by increasing Liquid hourly space velocity (LHSV) while the yields of kerosene and gas oil increase and no effect of LHSV on petroleum coke yield was observed, The specific gravity of gasoline, kerosene and gas oil decreases by increasing LHSV. The increase in LHSV (decrease in residence time) decreases the olefinic hydrocarbons of produced gas oil and fraction 350-450^°C. Sulfur content of produced coke and coking residue increases by increasing residence time while it changes slightly for kerosene and gas oil. By increasing the recycle ratio (RR), the yield of gas decreases while the coke yield increases. Sulfur content of gas oil and coking residue increases with an increase in the recycle ratio while it decreases for coke. Metals content of coke decreases with an increase in the recycle ratio and coke with accepted properties for aluminum anode manufacture could be produced when a recycle ratio of 1.4 was used.     

Design of planar concentric circular antenna arrays with reduced side lobe level using symbiotic organisms search

This paper investigates the design of concentric circular antenna arrays (CCAAs) with optimum side lobe level reduction using the Symbiotic Organisms Search (SOS) algorithm. Both thinned and full CCAAs are considered. SOS represents a rather new evolutionary algorithm for antenna array optimization. SOS is inspired by the symbiotic interaction strategies between different organisms in an ecosystem. SOS uses simple expressions to model the three common types of symbiotic relationships: mutualism, commensalism, and parasitism. These expressions are used to find the global minimum of the fitness function. Unlike other methods, SOS is free of tuning parameters, which makes it an attractive optimization method. The results obtained using SOS are compared to those obtained using several optimization methods, like Biogeography-Based Optimization (BBO), Teaching-Learning-Based Optimization (TLBO), and Evolutionary Programming (EP). It is shown that the SOS is a robust straightforward evolutionary algorithm that competes with other known methods.