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.     

Removal of Acid Orange 7 and Remazol Black 5 reactive dyes from aqueous solutions using a novel biosorbent

This study utilizes canola stalks (CS), an agro-residue, as a biosorbent to remove two different dyes, namely Acid Orange 7 (AO7) and Remozol Black 5 (RB5) from aqueous solutions. The effects of operational parameters on the efficiency of dye removal including pH, adsorbent mass, initial dye concentration and contact time have been investigated. For both tested dyes, the maximum absorption capacity was reached at initial pH 2.5 and 120 min contact time. The results showed that the absorption of both dyes depended on the pH of milieu, temperature, dye and CS concentrations. Freundlich and Langmuir models were used to analyze the obtained experimental data. The isotherms are found to be linear over the entire concentration range for both dyes. The highest value of linear correlation coefficients for AO7 (0.9926) and RB5 (0.9882) showed that the Langmuir is the best model to fit the experimental data. Kinetic study of absorption was done applying the pseudo first-order and the pseudo second-order equations. Absorption of both dyes could be well predicted by the pseudo second-order equation. The obtained results are very promising since: (i) high levels of dye removal (> 90%) were achieved with low contact times biosorbent/dye (less than 20 min contact); and (ii) the whole CS can be successfully used as biosorbent of AO7 and RB5 dyes in aqueous solution without needing any chemical modifications.     

Mechanical behavior and interphase structure in a silica-polystyrene nanocomposite under uniaxial deformation

The mechanical behavior of polystyrene and a silica-polystyrene nanocomposite under uniaxial elongation has been studied using a coarse-grained molecular dynamics technique. The Young's modulus, the Poisson ratio and the stress-strain curve of polystyrene have been computed for a range of temperatures, below and above the glass transition temperature. The predicted temperature dependence of the Young's modulus of polystyrene is compared to experimental data and predictions from atomistic simulations. The observed mechanical behavior of the nanocomposite is related to the local structure of the polymer matrix around the nanoparticles. Local segmental orientational and structural parameters of the deforming matrix have been calculated as a function of distance from nanoparticle's surface. A thorough analysis of these parameters reveals that the segments close to the silica nanoparticle's surface are stiffer than those in the bulk. The thickness of the nanoparticle-matrix interphase layer is estimated. The Young's modulus of the nanocomposite has been obtained for several nanoparticle volume fractions. The addition of nanoparticles results in an enhanced Young's modulus. A linear relation describes adequately the dependence of Young's modulus on the nanoparticle volume fraction.     

Effect of the Spectrum Sensing Period on the TCP Performance Over Cognitive Radio Ad-hoc Networks

Wireless Personal Communications - Modeling of spectrum occupancy by both primary and secondary users in the Cognitive Radio Ad-hoc Network (CRAHN) can be helpful to improve spectrum usage...     

Alteration of ADP-ribosylation in aging rat brain astrocytes

DNA damage and the enzyme poly (ADP-ribose) polymerase (PARP) associated with the pathogenesisof numerous age-related neurodegenerative disorders. Astrocytes play crucial roles in both support metabolicfunctions and cell viability of the brain. PARP regulates DNA damage and repair in the brain cells. In this study PARPactivity and DNA strand break were investigated in the astrocytes isolated from young and aged rat brain. Three and30-month-old rats were killed by decapitation and brains were removed onto an ice cooled glass plate. Astrocytes wereisolated by sucrose density gradient centrifugation and glutamine synthetase (GS) served as a marker of the astrocyteslineage. The specific activity of PARP was assayed in permeabilized cells by measuring the incorporation of the ADPribose moiety of [3H]NAD into the nuclear acceptor proteins. The rate of DNA strand breaks was determined usinga fluorescent dye and monitored spectrofluorimetry. An increase (about 75%) in the PARP activity was observed inthe whole homogenates of aged rats, whereas this rise was more pronounced (about 360%) when the reaction wasmeasured in the purified astrocyte preparations. The amount of DNA strand breaks was also higher in the astrocytesisolated from the aged brain as compared to that of young levels. The close relationship between the level of DNAstrand breaks and PARP activity in the astrocytes suggest that these cells are susceptible to the metabolic alterations inaging. It is concluded that the astrocytes PARP might be considered as a therapeutic target for combating age relatedneurodegenerative disorders.     

Mechanical behavior of a battery separator in electrolyte solutions

The structural integrity of the separator is crucial to the abuse tolerance of a battery. To estimate its stress level in a battery, the mechanical property of the separator in situ in the battery environment must be known. This work investigated the tensile behavior of a single layer polypropylene (PP) separator in electrolyte solutions for Li-ion batteries using a dynamic mechanical analyzer (DMA). The measurements were carried out in both dry (ambient) and wet conditions for both the machine direction (MD) and the transverse direction (TD). In the wet condition, samples were submerged either in a DMC solvent or in a electrolyte solution of 1.1 M LiPF6 in EC/DMC (1/1 by volume). The DMA experiments were performed under uniaxial tension, creep, and frequency sweep modes. The results in all three modes demonstrated that the mechanical properties of the separator were significantly lower in wet conditions. For instance, in the MD, relative to the dry condition, the ratio of the Young's modulus was about 0.49 and 0.52 for DMC and 1.1 M LiPF6 in EC/DMC, respectively. The results indicate that the mechanical properties measured in dry condition using samples that had been preconditioned in solutions are not sufficient to represent the in situ material behavior.     

Current Approaches in Improving Hemocompatibility of Polymeric Membranes for Biomedical Application

Suitable membranes for blood‐contacting medical applications need to be resistant in confrontation with blood proteins and cells, while possessing high blood compatibility and permeability at the same time. Herein, an overview of the recent advances and strategies that have been used to enhance the hemocompatibility of polymeric membranes is provided. The review focuses on two modification strategies: (i) physical modifications and (ii) chemical modifications. It also highlights the current progress in the design of hemocompatible‐functionalized membranes for biomedical applications. Subsequently, the commonly applied biocompatibility tests are also discussed and finally the future perspectives of the application of polymeric membranes in the biomedical field are presented.

     

A new extended matrix logarithm formulation for the simulation of viscoelastic fluids by spectral elements

This study presents a new algorithm developed in order to remove instabilities observed in the simulation of unsteady viscoelastic fluid flows in the framework of the spectral element method. In this study, we consider a particular model of the finite extensible nonlinear elastic family, FENE-P, but the method could be applied to other differential constitutive equations. Two distinct constraints for the FENE-P equation are imposed: (i) the square of the corresponding finite extensibility parameter of the polymer must be an upper limit for the trace of the conformation tensor and (ii) the eigenvalues of the conformation tensor should remain positive at all steps of the simulation. Negative eigenvalues cause the unbounded growth of instabilities in the flow. The proposed transformation is an extension of the matrix logarithm formulation originally presented by Fattal and Kupferman [1] and [2]. To evaluate the capability of this new algorithm with the classical conformation tensor, comprehensive studies have been done based on the linear stability analysis to show the influence of this method on the resulting eigenvalue spectra and explain its success to tackle high Weissenberg numbers. With this new method one can tackle high Weissenberg number flow at values of practical interest. A neat improvement of the computational algorithm with stable convergence has been demonstrated in this study.