Comparative studies of the rheological behavior and microstructural properties of emulsions (oil/distilled water phase) and (oil/Lias water phase)

Abstract

The rheological behavior of crude oil and their emulsions were investigated as a function of two water types (distilled water and the LIAS water). The focus of this work is to obtain more knowledge about the effect of LIAS water concentration, which used to maintain pressure and produced from production of crude oil in the oil fields Tin Fouye Tabankort-south Algeria, on the rheological properties of crude oil. The rheological parameters were measured by using AR-2000 rheometer at 15?°C under dynamic and shear testing conditions. The measured data were first classified into two groups for Newtonian and non-Newtonian fluids. Depends on the type and concentration of water, the non-Newtonian behavior was described in better way by the Casson, Power law and the Herschel–Bulkley models. The results indicated that the viscosity, the yield stress, the elastic modulus, (G′), the loss modulus, (G″), and the microstructure of the prepared emulsions not only varied with water concentration but also by water types.     

Coal gasification by microwave plasma in water vapour

The influence of several parameters on the H₂ and CO yields from gasification of a coal (Blanzy) by microwave plasma in water vapour, in a static system, is discussed. The yields of H₂ and CO significantly increase for low coal weights placed in the discharge illustrating that the gasification occurs on the surface of the coal layer. The time necessary for complete gasification and the gasification yields are measured for several initial weights of coal. The relative yields of H₂ and CO depend on the initial water vapour pressure and are independent of coal granulometry. The reactivity of a coal which was pre-reacted in the discharge is similar to that of an original coal, so a possible recycling of the solid can be envisaged.     

Permittivity and permeability measurement of microwave packaging materials

There has recently been a growing interest in using new packaging materials-dielectric and/or magnetic-in a wide variety of applications for controlling the microwave heating of food. The study of the thermal behavior of these products requires the accurate determination of the complex permittivity and permeability when the temperature varies, and when the materials are irradiated in specific conditions. One of the main challenges is to distinguish the dielectric losses from the magnetic ones. In this paper, a practical measurement method is proposed, which consists of irradiating a rod sample successively with a homogeneous electric-field distribution with a low magnetic field and with a homogeneous magnetic-field distribution with low electric field. An accurate and efficient electromagnetic analysis tool is used to generate a set of points, which allow the construction of several bilinear functions that relate the scattering parameters of the circuit to the complex values of /spl epsiv/ and /spl mu/ so that /spl epsiv/ and /spl mu/ can then be easily determined from experimental measurements in accordance to whatever the special irradiation conditions. Some results for test materials are presented and discussed.     

Evaluation of adipose tissue distribution in obese fa/fa Zucker rats by in vivo MR imaging: effects of peroxisome proliferator-activated receptor agonists

High-resolution MRI of obese (fa/fa) Zucker rats was investigated to characterize and assess in vivo adipose tissue distribution. Thirty animals were gavaged with a placebo, a PPAR activator (pioglitazone), or a dual PPAR activator (LM 4156). At day 15, T₁-weighted images were acquired in vivo using a 2TMRI system with a high in-plane spatial resolution (254 m). Fat volumes of selected territories were measured by image segmentation, and the retroperitoneal fat was weighed post-mortem. Body-weight gain was significant with pioglitazone (101.8±5.9 g, p<0.01 vs. placebo). The good quality of MR images allowed the delimitation and quantification of different fat territories. In response to pioglitazone, the retroperitoneal fat was more important compared to placebo (+23%, p<0.01) while subcutaneous fat was not different. No significant effects were observed with LM 4156. In vivo measurements of fat volumes were strongly correlated with ex vivo tissue weights (r=0.91). High-resolution MRI provides an in vivo measurement of adipose tissue distribution in obese Zucker rats. Specific fat depots of regions that were particularly involved in drug response were determined in vivo. Fat remodeling was observed with pioglitazone but not with a dual PPAR activator (LM 4156).     

The augmented weighted Tchebychev norm for optimizing a linear function over an integer efficient set of a multicriteria linear program

In this paper, we propose a new exact algorithm, using an augmented weighted Tchebychev norm, for optimizing a linear function on the efficient set of a multiple objective integer linear programming problem. This norm is optimized progressively by improving the value of the linear criteria and going through some efficient solutions. The method produced not only the best efficient solution of the linear objective function but also a subset of nondominated solutions that can help decision makers to select the best decision among a large set of Pareto solutions.     

Efficient numerical schemes for gradient vector flow

Since its publication more than 10 years ago, the gradient vector flow (GVF) technique has been used and adapted to various models and problems. Its effectiveness has greatly contributed to its popularity. The main drawback of GVF and its generalisation, however, is their expensive computation load and its consequence on the capture range. In this work, we propose and compare different efficient numerical schemes to solve the GVF and its generalisations.     

Robust H ∞ control for T–S fuzzy systems with time-varying delay

This article focuses on the problem of robust H _∞ control for uncertain T–S fuzzy systems with time-varying delay. By employing a novel technique, new delay-dependent stabilisation conditions for the existence of a robust H _∞ controller are obtained based on the parallel distributed compensation method. The result obtained is an important contribution as it establishes a new way that can reduce the conservatism without imposing any restrictions and computational efforts at the same time. In this article, all the conditions are shown in terms of linear matrix inequalities (LMIs), which can be solved efficiently by using LMI optimisation techniques. Two numerical examples are given to demonstrate the merits of the approach proposed in this article. Finally, application to control a truck-trailer is also given to demonstrate the effectiveness of the proposed design method.     

Data Services with uncertain and correlated semantics

Currently, a good portion of datasets on Internet are accessed through data services, where user’s queries are answered as a composition of multiple data services. Defining the semantics of data services is the first step towards automating their composition. An interesting approach to define the semantics of data services is by describing them as semantic views over a domain ontology. However, defining such semantic views cannot always be done with certainty, especially when the service’s returned data are too complex. In such case, a data service is associated with several possible semantic views. In addition, complex correlations may be present among these possible semantic views, mainly when data services encapsulate the same data sources. In this paper, we propose a probabilistic approach to model the semantic uncertainty of data services. Services along with their possible semantic views are represented in probabilistic service registry. The correlations among service semantics are modeled through a directed probabilistic graphical model (Bayesian network). Based on our modeling, we study the problem of compositing correlated data services to answer a user query, and propose an efficient method to compute the different possible compositions and their probabilities.     

Analysis of two-dimensional transient conduction–radiation problems in an anisotropically scattering participating enclosure using the lattice Boltzmann method and the control volume finite element method

This study deals with the performance evaluation of the lattice Boltzmann method (LBM) and the control volume finite element method (CVFEM) in terms of their abilities to provide accurate results in solving combined transient conduction and radiation mode problems in a two-dimensional rectangular enclosure containing an absorbing, emitting and anisotropically scattering medium. Coupling problems for mixed kind thermal boundary are worked out for reflective interfaces. Effects of various parameters are studied on the distributions of temperature, radiative and conductive heat fluxes. The results of the LBM in conjunction with the CVFEM have been found to compare very well with available results in the literature. So, the numerical approach is extended to deal with a practical combination of mixed boundary conditions in a transient multi-dimensional combined conductive radiative heat transfer problems in an emitting, absorbing, anisotropically scattering enclosure.