Effect of Nanocrystallization on Discharge Behavior and Microstructure of Plasma Electrolytic Oxidation on AZ31B Alloy

In this study AZ31B Magnesium alloy was pre-treated with surface mechanical attrition process (SMAT), for nanocrystallization, and subsequently plasma electrolytic oxidation was applied. Real-time imaging and microscopic investigation were used to study discharge events to reveal the pre-treatment effect on coating growth. SMAT processing developed a 100 nm nano-crystalline layer. Nano-crystallinity was verified by XRD and TEM studies which showed that treated area has crystalline size of about 30 nm. SEM studies revealed that in first minute number of discharges on nano-crystalline surface was 50% higher than microcrystalline surfaces. Number of discharge channels in both samples became nearly identical in longer treatment times. Most of the changes in growth rate are focused in first 2 minutes of coating. Calculations revealed that for pre-treated sample extracted volume of molten oxide through each discharges is significantly higher than non-treated sample while the number of discharges are less. However, number of discharges decline rapidly. While oxide layer grows the surface reactivity decreases.     

Mechanical and geometrical approaches applied to composite fabric forming

In this paper, we are interested in the forming of composite fabric by deep-drawing. Two approaches (geometrical and mechanical) are proposed for the simulation of the composite fabric forming. The geometrical approach is based on a fishnet model. It is well adapted to preliminary design phase and to give a suitable estimate of the resulting flat patterns. The mechanical approach is based on a meso-structural approach. It allows us to take into account the mechanical properties of composite fabric (fibres and resin) and the various dominant modes of deformation of fabrics during the forming process. During simulation of composite fabric forming, where large displacement and relative rotation of fibres are possible, severe mesh distortions occur after a few incremental steps. Hence an automatic mesh generation with remeshing capabilities is essential to carry out the finite element analysis. Some numerical simulations of forming process are proposed and compared with the experimental results in order to demonstrate the efficiency of the proposed approaches.     

The ANFIS-PSO strategy as a novel method to predict interfacial tension of hydrocarbons and brine

The interfacial tension of hydrocarbons and brine is known as one of the important parameters which are measured in petroleum and petrochemical industries for example the interfacial tension has straight effect on trapping of oil in a reservoir. In the present work the Adaptive neuro-fuzzy inference system (ANFIS) algorithm was used as a novel approach for estimation of interfacial tension between hydrocarbons and brine as function of pressure, temperature, carbon number of hydrocarbon and ionic strength of brine then the particle swarm optimization (PSO) was used to optimize the predicting model parameters.in order to better evaluation of performance of predicting algorithm the coefficient of determination (R²), average absolute relative deviation (AARD) and root mean squared error (RMSE) were estimated for different steps. The outcomes of this investigation expressed that proposed model has high potential for prediction of interfacial tension between hydrocarbons and brine.     

Dynamic stability enhancement of interconnected multi-source power systems using hierarchical ANFIS controller-TCSC based on multi-objective PSO

Suppression of the dynamic oscillations of tie-line power exchanges and frequency in the affected interconnected power systems due to loading-condition changes has been assigned as a prominent duty of automatic generation control (AGC). To alleviate the system oscillation resulting from such load changes, implementation of flexible AC transmission systems (FACTSs) can be considered as one of the practical and effective solutions. In this paper, a thyristor-controlled series compensator (TCSC), which is one series type of the FACTS family, is used to augment the overall dynamic performance of a multi-area multi-source interconnected power system. To this end, we have used a hierarchical adaptive neuro-fuzzy inference system controller-TCSC (HANFISC-TCSC) to abate the two important issues in multi-area interconnected power systems, i.e., low-frequency oscillations and tie-line power exchange deviations. For this purpose, a multi-objective optimization technique is inevitable. Multi-objective particle swarm optimization (MOPSO) has been chosen for this optimization problem, owing to its high performance in untangling non-linear objectives. The efficiency of the suggested HANFISC-TCSC has been precisely evaluated and compared with that of the conventional MOPSO-TCSC in two different multi-area interconnected power systems, i.e., two-area hydro-thermal-diesel and three-area hydro-thermal power systems. The simulation results obtained from both power systems have transparently certified the high performance of HANFISC-TCSC compared to the conventional MOPSO-TCSC.     

Ridge extraction and its application to surface meshing

Geometrical feature lines, such as ${{\mathcal{C}}}^1Geometrical feature lines, such as -discontinuity lines, lines of curvature, ridges, asymptotic lines, etc., provide useful information about the surface geometry. The inclusion of these lines into a surface mesh contributes to improving the quality of the geometrical approximation, independently from the element size. In particular, if the element size is locally large with respect to the minimal radius of curvature, then the geometrical approximation of the surface will generally be poor. In this case, the presence of ridges in the mesh improves the geometrical approximation. This paper proposes a new method to extract the extremal graph whose graph nodes are the umbilics and the extremal points, and edges are extremal lines. A function is also introduced to classify the extremal lines to be able to select the ridges from a parametric surface. The resulting graph of ridges is then simplified and integrated as a constraint in a classical surface mesh generation via an indirect approach. A numerical example will illustrate the pertinence of this method.

Boris Clémen?onEmail:

     

Interactive visual analysis of time-series microarray data

Estimating dynamic regulatory pathways using DNA microarray time-series can provide invaluable information about the dynamic interactions among genes and result in new methods of rational drug design. Even though several purely computational methods have been introduced for DNA pathway analysis, most of these techniques do not provide a fully interactive method to explore and analyze these dynamic interactions in detail, which is necessary to obtain a full understanding. In this paper, we present a unified modeling and visual approach focusing on visual analysis of gene regulatory pathways over time. As a preliminary step in analyzing the gene interactions, the method applies two different techniques, a clustering algorithm and an auto regressive (AR) model. This approach provides a successful prediction of the dynamic pathways involved in the biological process under study. At this level, these pure computational techniques lack the transparency required for analysis and understanding of the gene interactions. To overcome the limitations, we have designed a visual analysis method that applies several visualization techniques, including pixel-based gene representation, animation, and multi-dimensional scaling (MDS), in a new way. This visual analysis framework allows the user to quickly and thoroughly search for and find the dynamic interactions among genes, highlight interesting gene information, show the detailed annotations of the selected genes, compare regulatory behaviors for different genes, and support gene sequence analysis for the interesting genes. In order to enhance these analysis capabilities, several methods are enabled, providing a simple graph display, a pixel-based gene visualization technique, and a relation-displaying technique among gene expressions and gene regulatory pathways.     

Characterization of New Wire Gauze-Structured Packing: Experimental Study

Structured packings are usually employed for increasing the surface contact between vapor and liquid in the absorber and distillation of columns. Experimental investigations are performed to present a high-capacity new wire gauze-structured packing, namely, PACK-1300XY, which is the combination of PACK-1300X and PACK-1300Y. The new PACK-1300XY shows improved efficiency of separation and pressure drop. Comprehensive parametric investigations are carried out to calculate the efficiency of mass transfer and the wet/dry pressure drops under different operating conditions. The new wire gauze-structured packing reduces wet and dry pressure drops by more than 10 % in comparison to PACK-1300Y. In addition, PACK-1300XY decreases the height equivalent to a theoretical plate by more than 5 % compared to PACK-1300X.