Applying simulated annealing for designing cellular manufacturing systems using MDmTSP

The design of cellular manufacturing systems involves many structural and operational issues. One of the important design steps is the formation of part families and machine cells (cell formation). Despite a large number of papers on cell formation published worldwide, only a handful incorporates operation sequence in layout design (intra-cell move calculations). We propose a solution to solve the part-family and machine-cell formation problem considering the within-cell layout problem, simultaneously. In this paper, the cellular manufacturing system is formulated as a multiple departures single destination multiple travelling salesman problem (MDmTSP) and a solution methodology based on simulated annealing is proposed to solve the formulated model. Numerical examples show that the proposed method is efficient and effective in finding optimal solutions. The results also indicate that the proposed approach performs well compared to some well-known cell formation methods.     

SipaaS: Spot instance pricing as a Service framework and its implementation in OpenStack

Designing dynamic pricing mechanisms that efficiently price resources in line with a provider's profit maximization goal is a key challenge in cloud computing environments. Despite the large volume of research published on this topic, there is no publicly available software system implementing dynamic pricing for Infrastructure as a Service cloud spot markets. This paper presents the implementation of a framework called Spot instance pricing as a Service (SipaaS) that supports an auction mechanism to price and allocate virtual machine instances. SipaaS is an open‐source project offering a set of web services to price and sell virtual machine instances in a spot market resembling the Amazon EC2 spot instances. Cloud providers, who aim at utilizing SipaaS, should install add‐ons in their existing platform to make use of the framework. As an instance, we provide an extension to the Horizon – the OpenStack dashboard project – to employ SipaaS web services and to add a spot market environment to OpenStack. To validate and evaluate the system, we conducted an experimental study with a group of 10 users utilizing the provided spot market in a real environment. Results show that the system performs reliably in a practical test environment. Copyright © 2015 John Wiley & Sons, Ltd.     

The effect of particle size,irrigation rate and aeration rate on column bioleaching of uranium ore

The effect of hydrodynamic factors such as particle size, irrigation rate and aeration rate on the dissolution of uranium by Acidithibacillus ferrooxidans in column reactor was studied. Response surface methodology (RSM) was applied to predict the behavior of effective parameters and their interactions on the bioleaching process. Under the optimum conditions particle size of 5 mm, irrigation rate of 0.34 L/m²/min and aeration rate of 210 L/m²/min, the maximum value of uranium recovery was 63.85% for 19 days. The results from the statistical model and the experimental data showed good agreement and the most effective factor was the aeration rate. The interaction between particle size and irrigation rate has a negative effect and two other interactions have a positive effect on uranium recovery. Analysis of bioleaching residue confirmed the formation of K-jarosite on the surface of particles. The modified kinetic model at optimum conditions showed that cathodic ferric reduction is the rate controlling step on uranium bioleaching recovery.     

The Case for Quantitative Process Management

This article introduces a special section on "Embedding Statistical Methods into Software Engineering Practices." It provides a background on Quantitative Process Management and makes the case for why these methods are important. It presents an example of how a model can be developed to predict project outcomes by using data emerging from the performance of process tasks. It discusses how these methods can be used with different software development paradigms. It ends by summarizing develops needed in five different communities in order for these methods to be widely adopted.     

An optimization problem related to balancing loads on SONET rings

We provide a model and a set of solution techniques for an important problem arising in the design of survivable telecommunication networks utilizing fiber-optics-based technologies. The emergence of a synchronous standard for optical signaling called SONET allows for an economic implementation of ring designs that provides protection for high capacity services. An objective is to choose a loading of the demands onto a ring design that minimizes associated equipment and facility costs while providing capacity for alternative routing should some link or node fail. After the computational complexity of the problem has been determined, three approximation heuristics, including a mathematical programming dual-ascent solution technique, are described and compared. The heuristics are being successfully applied to actual network design problems arising in Bell operating companies and other telecommunication providers.     

A genetic algorithm for optimization problems with fuzzy relation constraints using max-product composition

We consider nonlinear optimization problems constrained by a system of fuzzy relation equations. The solution set of the fuzzy relation equations being nonconvex, in general, conventional nonlinear programming methods are not practical. Here, we propose a genetic algorithm with max-product composition to obtain a near optimal solution for convex or nonconvex solution set. Test problems are constructed to evaluate the performance of the proposed algorithm showing alternative solutions obtained by our proposed model.     

Thermophysical and rheological behavior of polystyrene/silica nanocomposites: Investigation of nanoparticle content

In this work, solvent blending in combination with extruding are applied to provide polystyrene/silica nanocomposite specimens. Transmission electron microscope (TEM) and scanning electron microscope (SEM) show same nanoparticle dispersion in PS matrix in low to high filler loadings. Differential scanning calorimetry (DSC), dynamic mechanical thermal analyzer (DMTA) and thermogravimetric analyzer (TGA) were used to study the thermophysical characteristic of the nanocomposites in solid state. In addition, the melt state rheological behavior of the samples was investigated under constant and zero shear rates. Interestingly, different behaviors were detected in nanocomposites in low and high nanoparticle loadings. In addition, rheological characteristics of molten polymer are dramatically affected in samples with low nanosilica concentration while stabilized in high filler loadings.     

Improved Method of Direction Finding for Non Circular Signals with Wavelet Denoising Using Three Parallel Uniform Linear Arrays

Wireless Personal Communications - Pot experiments were conducted to study the effects of different cadmium (Cd) levels (0, 75, 150, 300 and 600 mg kg?1) on the growth,...     

Design and implementation of an information system for performance assessment of management and organization in a gas refinary

Abstract

The objective of this study is to present an information system for assessment of management and organization in a gas refinery. To achieve the objective of this study, Balanced Score Card (BSC) methodology was utilized to categorize management and organization indicators into four categories. The data related to a five year period was then collected to provide a benchmark for the refinery. Furthermore, the data from 19 developed and developing countries were collected for the purpose of benchmarking. A t‐test was then introduced to benchmark the refinery's management and organization indicators. Moreover, Data Envelopment Analysis (DEA) was used to analyze and further assess the violated indicators. Finally, an integrated information system was designed in .Net environment by C#. It was introduced to facilitate the assessment of management and organization indicators. This is the first study that introduces an information system for performance assessment of management and organization in a gas refinery by integration of BSC, DEA and t‐test.     

Effect of α-Fe2O3 addition on the morphological,optical and decolorization properties of ZnO nanostructures

Visible light sensitive photocatalysts of Fe₂O₃/ZnO nanocomposites were prepared by a simple solid-state reaction method, using zinc acetate, α-Fe₂O₃ and sodium hydroxide at room temperature. The products were characterized by scanning electron microscopy, powder X-ray diffraction, N₂ adsorption–desorption measurement, UV–vis absorption, and photoluminescence spectroscopy and used for photodecolorization of Congo red. The characterization results showed that the morphology, crystallite size, BET surface area and optical absorption of the samples varied significantly with the Fe³⁺ to Zn²⁺ ratios. The nanocomposites show two absorption edges at ultraviolet and visible region. The optical band gap values of these nanocomposites were calculated to be about 3.98–3.81 eV and 2.88–2.98 eV, which show a red shift from that of pure ZnO. These red shifts are related to the formation of Fe s-levels below the conductive band edge of ZnO and effectively extend the absorption edge into the visible region. The growth mechanisms of the samples are proposed. These nanocomposites showed high decolorization ability in visible light with wavelength up to about 400 nm. Among the samples, Fe₂O₃/ZnO nanoflower (molar ratio of Fe³⁺ to Zn²⁺ is 1:100) exhibited higher decolorization efficiency than the other nanocomposites. It could be considered as a promising photocatalyst for dyes treatment.