A Logarithmic-Quadratic Proximal Method for Variational Inequalities

We present a new method for solving variational inequalities on polyhedra. The method is proximal based, but uses a very special logarithmic-quadratic proximal term which replaces the usual quadratic, and leads to an interior proximal type algorithm. We allow for computing the iterates approximately and prove that the resulting method is globally convergent under the sole assumption that the optimal set of the variational inequality is nonempty.     

The influence of preservation method and time on the δ13C value of dissolved inorganic carbon in water samples

The precise δ¹³C value of dissolved inorganic carbon (DIC) is important for various types of ecological studies. Without a preservation agent, microbial degradation of organic compounds continues in water samples and the δ¹³C value of DIC will become more depleted with time. HgCl₂ or acidification is often used to prevent microbial activity in water samples collected for carbon isotope ratio analyses of DIC. Mercury compounds are toxic and result in waste disposal problems. Other inhibiting agents or preservation methods are therefore needed. Two possible solutions are to use copper sulphate (CuSO₄) as a preservative agent or to acidify water samples with phosphoric acid (H₃PO₄) within 12 mL measurement Exetainers® (septum‐capped vials). We prepared a set of lake water samples in three types of vials: glass vials with silicone/PTFE septa, high‐density polyethylene vials (HD‐PE, scintillation vials) and Exetainers (12 mL) with butyl rubber septa. Samples in glass and PE vials were preserved with and without CuSO₄, whereas lake water was injected into the Exetainer and acidified with H₃PO₄. Isotope ratios were measured in two laboratories over 6 months. The δ¹³C values of DIC systematically increased with storage time for samples preserved in glass and PE vials with and without CuSO₄. A strong correlation between a decrease of CO₂ concentration and an increase in DIC δ¹³C values was found. The δ¹³C values and DIC concentrations were stable for 6 months in acidified samples stored in Exetainers with butyl rubber septa. Therefore, we conclude that the best method for up to 6 months of storage is to inject samples in the field into butyl rubber septum capped Exetainers® containing H₃PO₄, thereby avoiding the use of preservatives. Copyright © 2009 John Wiley & Sons, Ltd.     

Structural,M?ssbauer spectroscopy,magnetic properties,and thermal measurements of Y(3-x)Dy_x Fe_5O_(12)

Yttrium iron garnet powder samples((3-x)Dy_x Fe_5O_(12)), where part of yttrium ions are substituted by dysprosium ions with different concentrations are prepared by the solid state reaction method. The properties of the prepared samples are examined by different methods such as x-ray diffraction(XRD), Mssbauer spectroscopy, macroscopic magnetization measurements, and thermal measurements. The XRD measurements show that all the samples reveal the presence of a single garnet phase with a BCC structure. Room temperature Mssbauer spectra indicate that iron ions occupy three magnetic sites, i.e., two octahedral sites and one tetrahedral site. The saturation magnetization and the initial magnetic susceptibility decrease with the increase of Dy~(3+) substitution. The Curie temperature obtained from the thermal measurements seems to be independent of Dy~(3+) substitution.     

Radiation modelling in oxy-fuel combustion scenarios

Coal combustion was simulated in a lab-scale furnace and a full scale utility boiler at air-burn, oxy-combustion with dry- and wet-flue gas recycles. Good agreement was obtained between the numerical predictions and experimental measurements. The study confirmed that certain dry and wet recycle ratios imitate the temperature and heat transfer characteristics found in air combustion. The performances of five grey models to predict the radiative properties of gases in the simulations were examined. Emissivity correlations developed for purely CO₂ media were not found to be suitable to predict the property at low H₂O/CO₂ ratios encountered during dry-recycle. Therefore, a new total emissivity correlation and a weighted-sum-of-grey-gases (WSGG) model were formulated to address the shortcomings and inaccuracies in existing grey gas models under oxy-firing. The new WSGG model with 4 band intervals was found to perform well in test cases that were representative of air- and oxy-firing conditions in boilers.     

Investigation of Cyber-Security and Cyber-Crimes in Oil and Gas Sectors Using the Innovative Structures of Complex Intuitionistic Fuzzy Relations

Recently, there has been enormous development due to advancements in technology. Industries and enterprises are moving towards a digital system, and the oil and gas industries are no exception. There are several threats and risks in digital systems, which are controlled through cyber-security. For the first time in the theory of fuzzy sets, this research analyzes the relationships between cyber-security and cyber-crimes in the oil and gas sectors. The novel concepts of complex intuitionistic fuzzy relations (CIFRs) are introduced. Moreover, the types of CIFRs are defined and their properties are discussed. In addition, an application is presented that uses the Hasse diagram to make a decision regarding the most suitable cyber-security techniques to implement in an industry. Furthermore, the omnipotence of the proposed methods is explained by a comparative study.     

Phantom and non-phantom dark energy: The cosmological relevance of non-locally corrected gravity

In this Letter we have investigated the cosmological dynamics of non-locally corrected gravity involving a function of the inverse d'Alembertian of the Ricci scalar, f(^□−1R)$f({\square }^{\mathrm{-1}}R)$. Casting the dynamical equations into local form, we derive the fixed points of the dynamics and demonstrate the existence and stability of a one parameter family of dark energy solutions for a simple choice, f(^□−1R)∼exp(α^□−1R)$f({\square }^{\mathrm{-1}}R)\sim \exp (\alpha {\square }^{\mathrm{-1}}R)$. The effective EoS parameter is given by, weff=(α−1)/(3α−1)$w_{\mathrm{eff}}=(\alpha -1)/(3\alpha -1)$ and the stability of the solutions is guaranteed provided that 1/3<α<2/3$1/3<\alpha <2/3$. For 1/3<α<1/2$1/3<\alpha <1/2$ and 1/2<α<2/3$1/2<\alpha <2/3$, the underlying system exhibits phantom and non-phantom behavior respectively; the de Sitter solution corresponds to α=1/2$\alpha =1/2$. For a wide range of initial conditions, the system mimics dust like behavior before reaching the stable fixed point. The late time phantom phase is achieved without involving negative kinetic energy fields. A brief discussion on the entropy of de Sitter space in non-local model is included.     

General Solution for Unsteady Natural Convection Flow with Heat and Mass in the Presence of Wall Slip and Ramped Wall Temperature

This work is focused on the effect of heat and mass transfer with unsteady natural convection flow of viscous fluid along with ramped wall temperature under the assumption of the slip wall condition at the boundary. Analytical solutions are obtained by using Laplace transformation to the non-dimensional set of governing equations containing velocity, temperature and concentration. Moreover, the expression for skin-friction is derived by differentiating the analytical solutions of fluid velocity. Numerical tables for Skin-friction, Sherwood number and Nusselt-number are examined. For the physical aspects of the flow, we use various values of involved physical parameters such as Prandtl number (Pr), slip parameter ($\eta$), Schmidt number (Sc), buoyancy ratio parameter ($N$), Sherwood number (Sh), and time $(t)$. Additionally, the general solutions are plotted graphically and a comprehensive theoretical section of numerical discussions is included.     

Adsorption of a cationic surfactant onto cellulosic fibers I. Surface charge effects

The adsorption of four cationic surfactants with different alkyl chain lengths on cellulose substrates was investigated. Cellulose fibers were used as model substrates, and primary alcohol groups of cellulose glycosyl units were oxidized into carboxylic groups to obtain substrates with different surface charges. The amount of surfactant adsorbed on the fiber surface, the fiber zeta-potential, and the amount of surfactant counterions (Cl(-)) released into solution were measured as a function of the surfactant bulk concentration, its molecular structure, the substrate surface charge, and the ionic strength. The contribution of each of these parameters to the shape of the adsorption isotherms was used to verify if surfactant adsorption and self-assembly models usually used to describe the behavior of surfactant/oxide systems can be applied, and with which limitations, to describe cationic surfactant adsorption onto oppositely charged cellulose substrates.     

Characterization of SU-8 for electrokinetic microfluidic applications

The characterization of SU-8 microchannels for electrokinetic microfluidic applications is reported. The electroosmotic (EO) mobility in SU-8 microchannels was determined with respect to pH and ionic strength by the current monitoring method. Extensive electroosmotic flow (EOF), equal to that for glass microchannels, was observed at pH > or =4. The highest EO mobility was detected at pH > or =7 and was of the order of 5.8 x 10(-4) cm(2) V(-1) s(-1) in 10 mM phosphate buffer. At pH < or =3 the electroosmotic flow was shown to reverse towards the anode and to reach a magnitude of 1.8 x 10(-4) cm(2) V(-1) s(-1) in 10 mM phosphate buffer (pH 2). Also the zeta-potential on the SU-8 surface was determined, employing lithographically defined SU-8 microparticles for which a similar pH dependence was observed. SU-8 microchannels were shown to perform repeateably from day to day and no aging effects were observed in long-term use.