New approach to mimic rheological actual shear rate under wall slip condition

Engineering with Computers - The presence of wall slip in concentrated suspensions affect the rheological measurements such as shear stress, shear rate, and viscosity. The measured shear rate will...     

Energy efficient scheduling in local area networks

Wireless Networks - In Wireless Local Area Networks (WLAN), portable devices such as notebooks, tabs, and smart phones are powered by batteries with limited energy. With the great increase of using...     

Aging of novel membranes made of PVA and cellulose nanocrystals extracted from Egyptian rice husk manufactured by compression moulding process

Novel membranes consisting of polyvinyl alcohol (PVA), cellulose nanocrystals (CNCs) originated from Rice Husk (RH), Glutaraldehyde (GLA) and Glycerine (G) were manufactured by the compression moulding process. Rice husk is a new source to isolate pure cellulose nanocrystals via mechanical and chemical treatment. The biodegradability of the membranes has been evaluated using UV accelerated weathering as well as a soil burial test. The morphology of membranes (PVA/RH-CNCs) was characterized by using the Scanning Electron Microscope (SEM). The chemical structure of the membranes (PVA/RH-CNCs) was characterised by Fourier-Transformation Infrared (FTIR) spectroscopy as well as wide-angle X-ray diffraction. The mechanical properties of the membranes were evaluated using standard techniques. Swelling and weight loss resulting from biodegradation were also evaluated. The results showed that the developed transient membranes can be used as food packaging bags owing to biodegradability (weight loss) under irradiation and during soil burial.     

Recursive least squares estimation methods for a class of nonlinear systems based on non-uniform sampling

Many dynamic processes in practice have nonlinear characteristics and must be described by using nonlinear models. It remains to be a challenging problem to build the models of such nonlinear systems and to estimate their parameters. This article studies the parameter estimation problem for a class of Hammerstein-Wiener nonlinear systems based on non-uniform sampling. By means of the auxiliary model identification idea, an auxiliary model-based recursive least squares algorithm is derived for the systems. In order to enhance the computational efficiency, an auxiliary model-based hierarchical least squares algorithm is proposed by utilizing the hierarchical identification principle. The simulation results confirm the effectiveness of the proposed algorithms.     

Full and reduced-order H∞ filtering of Takagi–Sugeno fuzzy time-varying delay systems: Input–output approach

This article addresses the issue of delay-dependent H_∞ filtering design for TakagiŮSugeno fuzzy time-varying delay systems using the input–output approach. A three-term approximation model has been used to transform the original system into two interconnected subsystems. Since the nonquadratic Lyapunov–Krasovskii functional requires to deal with the membership function's (MF) time derivative, upper-bound inequalities have been added to the obtained conditions. Based on the scaled small gain theorem, nonquadratic Lyapunov–Krasovskii functional approach and considering the bounds of the MF time-derivative, the H_∞ full- and reduced-order filters are designed and then formulated in terms of linear matrix inequalities. Finally, illustrative examples are presented to demonstrate the validity of the proposed methods.     

Electro-osmotic flow of fractional second-grade fluid with fractional Cattaneo heat flux through a vertical microchannel

This study investigates the unsteady electro-osmotic flow (EOF) of a fractional second-grade fluid through a vertical microchannel with convection heat transfer. The fractional Cattaneo heat flux model will be used to modify the heat equation. The solutions for the velocity and the temperature have been derived by employing the Laplace and finite Fourier sine transforms and their numerical inverses. The results show that at the beginning of the time period, the fractional parameter postpones the movement of the fluid. Furthermore, the results show that at the high values of retardation time (non-Newtonian case), the required time for the velocity and the flow rate to reach the steady state increases. Moreover, the heat relaxation time reduces the heat transfer until a critical time, and then the effect reverses.     

Comparative study of the optimal operation of methane reforming process in cylindrical and spherical reactors using multi-objective optimization

We present a multi-objective optimization (MOO) based study of the optimal operation of methane reformer for spherical reactor and compare the results with the ones for the cylindrical reactor. We considered three objective functions for this comparative study, namely maximization of hydrogen production, minimization of carbon dioxide emission, and minimization of power loss due to pressure drop in the reactor. We solve four MOO problems, which include three 2-objective problems with each pair of the aforementioned three objectives. In addition, we also solve a three objective problem considering all the three objectives. The optimization variables considered for the MOO study correspond to the feed conditions. Specifically, the three variables include the inlet temperature and the molar feed ratios of oxygen to methane & steam to methane.     

Conditional Preference Networks with User's Genuine Decisions

User's choices involve habitual behavior and genuine decision. Habitual behavior is often expressed using preferences. In a multiattribute case, the Conditional Preference Network (CP-net) is a graphical model to represent user's conditional ceteris paribus (all else being equal) preference statements. Indeed, the CP-net induces a strict partial order over the outcomes. By contrast, we argue that genuine decisions are environmentally influenced and introduce the notion of “comfort” to represent this type of choices. In this article, we propose an extension of the CP-net model that we call the CP-net with Comfort (CPC-net) to represent a user's comfort with preferences. Given that preference and comfort might be two conflicting objectives, we define the Pareto optimality of outcomes when achieving outcome optimization with respect to a given CPC-net. Then, we propose a backtrack search algorithm to find the Pareto optimal outcomes. On the other hand, two outcomes can stand in one of six possible relations with respect to a CPC-net. The exact relation can be obtained by performing dominance testing in the corresponding CP-net and comparing the numeric comforts.