Continuous size-based focusing and bifurcating microparticle streams using a negative dielectrophoretic system

Dielectrophoresis (DEP) is an electrokinetic phenomenon which is used for manipulating micro- and nanoparticles in micron-sized devices with high sensitivity. In recent years, electrode-based DEP by patterning narrow oblique electrodes in microchannels has been used for particle manipulation. In this theoretic study, a microchannel with triangular electrodes is presented and a detailed comparison with oblique electrodes is made. For each shape, the behavior of particles is compared for three different configurations of applied voltages. Electric field, resultant DEP force, and particle trajectories for configurations are computed by means of Rayan native code. The separation efficiency of the two systems is assessed and compared afterward. The results demonstrate higher lateral DEP force, responsible for particle separation, distributed wider across the channel width for triangular shape electrodes in comparison with the oblique ones. The proposed electrode shape also shows the ability of particle separation by attracting negative DEP particles to or propelling them from the flow centerline, according to the configuration of applied voltages. A major deficiency of the oblique electrodes, which is the streamwise variation of the lateral DEP force direction near the electrodes, is also eliminated in the proposed electrode shape. In addition, with a proper voltages configuration, the triangular electrodes require lower voltages for particle focusing in comparison with the oblique ones.     

Achieving dynamic adaptation via management and interpretation of runtime models

In this article, we present a generic model-centric approach for realizing fine-grained dynamic adaptation in software systems by managing and interpreting graph-based models of software at runtime. We implemented this approach as the Graph-based Runtime Adaptation Framework (GRAF), which is particularly tailored to facilitate and simplify the process of evolving and adapting current software towards runtime adaptivity. As a proof of concept, we present case study results that show how to achieve runtime adaptivity with GRAF and sketch the framework's capabilities for facilitating the evolution of real-world applications towards self-adaptive software. The case studies also provide some details of the GRAF implementation and examine the usability and performance of the approach.     

A new mathematical model for integrating all incidence matrices in multi-dimensional cellular manufacturing system

In the past several years, many studies have been carried out on cellular manufacturing based on a two-dimensional machine–part incidence matrix. Since workers have important role in doing jobs on machines, assignment of workers to cells becomes a crucial factor for fully utilization of cellular manufacturing systems. In this paper, an attempt is made to solve cell formation problem and minimize the number of voids and exceptional elements in a three dimensional (cubic) machine–part–worker incidence matrix. The proposed mathematical model captures the capability of workers in doing different jobs. To demonstrate the effectiveness of the proposed model, the solution of some test problems is compared with the literature method.     

Essay book review

OUR COMMON FUTURE, World Commission on Environment and Development, Oxford University Press, Oxford, 1987, 383 pp. (£5.95 Paperback)     

Synthesis of polymeric electrospun nanofibers for application in waterproof‐breathable fabrics

This study focuses waterproof‐breathable fabric development by applying electrospun web of polyurethane (PU), PAN, and PES directly onto the substrate fabric. Advantages of textile fabrics of elastomeric nanofibrous membranes over gortex specimen are the mass production feasibility, high elastomeric properties, more body comfort parameters, and fabric production without holes and needle traces formation. In this work, we identified the PU nanofibrous membrane as the best and useful web for application in waterproof‐breathable fabrics. Air permeability, water vapor transport rate, and resistance to water penetration average value for the prepared PU fibers web (sample of S1) were about 10 ml/s, 430 g/m²/24 h, 15 cm H₂O. To improve waterproof‐breathable characteristics of the membrane, the effects of electrospinning parameters on the fibers morphology and waterproof‐breathable characteristics were investigated. PU concentration of 12% (w/w) and electrospinning voltage of 12 kV were identified as optimal conditions to reach uniform and fine PU nanofibers formation without any beads. Air permeability, water vapor transport rate, and resistance to water penetration average value for the final sample were recorded as about 2.5 ml/s, 840 g/m²/24 h, and 44 cm H₂O, correspondingly. POLYM. ENG. SCI. 56:143–149, 2016. © 2015 Society of Plastics Engineers     

Variance‐based global sensitivity analysis for fuzzy random structural systems

There have been increasing advances in the sophisticated approaches like fuzzy randomness to handle different uncertainties in civil engineering; however, less attention has been paid to the formulation of a sensitivity analysis for fuzzy random structural systems. In this study, the main objective is to present the formulation of fuzzy Sobol sensitivity indices to quantify the influence of fuzzy random structural parameters. Meanwhile, uncertainty in derivation of limit states and acceptance criteria in collapse analysis is addressed briefly and treated using fuzzy model parameters. To show the application of the established sensitivity test, the collapse behavior of a steel moment frame subjected to sudden column removal is evaluated thoroughly. The proposed fuzzy sensitivity indices are determined for the problem and the overall influence of fuzzy acceptance criteria on the collapse assessment is shown using fragility analysis. The results show that the presented fuzzy sensitivity analysis can give detailed insight into the characteristics of fuzzy random systems, and the epistemic uncertainty in derivation of limit states can have significant effects on the reliability‐based collapse analysis. It is worth mentioning that to alleviate high computational demands in fuzzy probabilistic collapse analysis, a neural network metamodel is applied in conjunction with the genetic algorithm which is also of practical value to engineers and researchers.