Entropy Analysis of a Coupled‐Convection Flow through a Vertical Channel Partially Filled by a Porous Medium with Injection/Suction and Slip Boundary Conditions

Flow fields, thermal fields, and entropy generation have been investigated for fully developed mixed convection flow between two vertical porous plates. The vertical channel is partially filled by a porous medium, and channel walls are subjected to a constant injection velocity at the left wall and constant suction velocity at the right wall. The viscous dissipation effects and velocity slip for the longitudinal component of the velocity at the channel walls are also taken into account. The momentum and energy equations for the mixed convection problem in the vertical channel are solved by means of the perturbation series method, by taking perturbation parameter proportional to the Brinkman number. For the present problem, numerical solution is also obtained and compared with the analytical solution. The effects of various pertinent parameters on the velocity distribution, temperature distribution, entropy generation rate, and Bejan number are investigated and discussed graphically.     

Intrusion detection in voice over IP environments

In this article, we present the design of an intrusion detection system for voice over IP (VoIP) networks. The first part of our work consists of a simple single- component intrusion detection system called Scidive. In the second part, we extend the design of Scidive and build a distributed and correlation-based intrusion detection system called Space Dive. We create several attack scenarios and evaluate the accuracy and efficiency of the system in the face of these attacks. To the best of our knowledge, this is the first comprehensive look at the problem of intrusion detection in VoIP systems. It includes treatment of the challenges faced due to the distributed nature of the system, the nature of the VoIP traffic, and the specific kinds of attacks at such systems. Y.-S. Wu and V. Apte contributed equally to the paper.     

Perceiving individuals and groups: Expectancies, dispositional inferences, and causal attributions.

Two experiments investigated differences in forming impressions of individual and group targets. Experiment 1 showed that when forming an impression of an individual, perceivers made more extreme trait judgments, made those judgments more quickly and with greater confidence, and recalled more information than when the impression target was a group. Experiment 2 showed that when participants were forming an impression of an individual, expectancy-inconsistent behaviors spontaneously triggered causal attributions to resolve the inconsistency; this was not the case when the impression target was a group. Results are interpreted as reflecting perceivers' a priori assumptions of unity and coherence in individual versus group targets. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Magnetic-nanoparticle-doped carbogenic nanocomposite: an effective magnetic resonance/fluorescence multimodal imaging probe

A novel and facile approach is developed to synthesize a magnetic nanoparticle (iron oxide)-doped carbogenic nanocomposite (IO-CNC) for magnetic resonance (MR)/fluorescence imaging applications. IO-CNC is synthesized by thermal decomposition of organic precursors in the presence of Fe(3) O(4) nanoparticles with an average size of 6 nm. IO-CNC shows wavelength-tunable fluorescence properties with high quantum yield. Magnetic studies confirm the superparamagnetic nature of IO-CNC at room temperature. IO-CNC shows MR contrast behavior by affecting the proton relaxation phenomena. The measured longitudinal (r(1) ) and transverse (r(2) ) relaxivity values are 4.52 and 34.75 mM(-1) s(-1) , respectively. No apparent cytotoxicity is observed and the nanocomposite shows a biocompatible nature. In vivo MR studies show both T(1) and T(2) * contrast behavior of the nanocomposite. Fluorescence imaging indicates selective uptake of IO-CNC by macrophages in spleen.     

Diffusion and sorption of sulfur mustard and bis(2‐chloroethyl)ether in elastomers: A comparative study

Bis(2‐chloroethyl)ether, a nonvesicant and easy to handle chemical, was proposed as a model compound for the vesicant sulfur mustard (SM) in routine permeation testing of protective devices. The proposition was based on detailed studies on sorption of these chemicals in elastomers. From the sorption plots and permeation parameters, it was found that the model compound diffuses faster than SM, and the diffusion follows Fickian kinetics. Free volume models, such as those developed by Lee and Salame, together with solubility and thermodynamic interaction parameters, validated the observed sorption phenomenon and afforded a criterion for predicting the barrier properties of elastomers. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2472–2479, 2000     

Sorption of sulfur mustard and its oxygen analog in black and nonblack-filled butyl rubber membranes

Butyl rubber (IIR) membranes containing a 0–50% volume fraction of carbon black (GPF N660) or nonblack fillers (talc/precipitated CaCO₃/fullers earth) were prepared by solution casting and evaluated for permeation resistance to the vesicant, bis(2-chloroethyl)sulfide, or sulfur mustard (SM) and its oxygen analog (OA), bis(2-chloroethyl)ether. The diffusivity of the chemicals was determined from the breakthrough time (BTT), obtained using the spot disc test and a gravimetric method. The permeation parameters, calculated from the sorption data, were used to determine an optimum filler content for maximum protection against SM. To investigate the effect of carbon loading on the permeation properties of IIR, the permeation of SM and OA in carbon-loaded black membranes was compared with nonblack membranes and interpreted in terms of the dispersion of carbon in the membranes. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 503–511, 1998     

Synthesis and Application of Palm Fatty Acid Distillate Based Alkyd Resin in Liquid Detergent

Palm fatty acid distillate (PFAD) is the by-product obtained during physical refining of crude palm oil, which mainly consists of free fatty acids along with minor amounts of glycerides, bioactive compounds such as tocopherols, tocotrienols, phytosterols, squalene, other hydrocarbons. In the present work, an eco-friendly alkyd resin was prepared using sustainable feedstock such as PFAD along with rosin. The various physico-chemical properties of PFAD-based alkyd resin (PFAD-AR) such as acid value, saponification value, viscosity and volatile matter were determined and compared to palm oil based alkyd resin (PO-AR). The structural properties of the alkyd resins were investigated using Fourier transform infrared (FTIR) and proton nuclear magnetic resonance (¹H NMR) spectroscopic techniques. The study presents the utilization of PFAD-based alkyd resin with sodium lauryl sulfate (SLS) and sodium lauryl ether sulfate (SLES) in the liquid detergent formulation. The performance properties of the PFAD-based alkyd resin liquid detergent formulations such as surface tension, wetting power and detergency were comparable with palm oil based alkyd resin liquid detergent formulations and with commercial liquid detergent (CLD). Surface tensions of liquid detergent formulations varied from 20 to 30 mN/m with decrease in concentration. The foaming properties of alkyd resin based liquid detergents are reduced with the increase in the amount of alkyd resin polymer in the formulations. Therefore, it has potential application as a foam reducer in detergent for washing machines.     

Study of FePt films prepared by reactive sputtering

In the present study, ⁵⁷FePt films are prepared with reactive ion beam sputtering using mixture of argon and nitrogen gases. Energy-dispersive X-ray reflectivity is used to estimate the thickness of the as-deposited films. Structural and magnetic properties of the as-deposited and annealed films are studied using grazing incidence X-ray diffraction (GIXRD), magneto-optical Kerr effect (MOKE) and conversion electron Mossbauer spectroscopy (CEMS). Significant difference in structural and magnetic properties i.e., formation of ordered L1₀ phase and perpendicular magnetic anisotropy are observed for the films prepared with mixture of nitrogen and argon as compared to the film prepared with argon only. From the GIXRD, peaks corresponding to the ordered face-centred tetragonal FePt phase are observed for the films prepared with mixture gas. The results of CEMS clearly show the perpendicular magnetic anisotropy (PMA) for the films prepared with mixture of nitrogen and argon. The observed enhanced chemical ordering and the development of PMA in the films prepared with mixture gas is due to the role played by the defects created as a consequence of nitrogen escape in the films with high temperature annealing.     

Effective interfacial area in irrigated packed columns

A generalized correlation is proposed for the values of effective interfacial area duing Vaporization, Absorption with and without Chemical Reaction and the values of wetted surface area in terms of dimensionless numbers. The values of effective interfacial area are analysed based on the concept of static and dynamic area, which appears to represent the mechanism of mass trasfer for the above cases.A generalized correlation in terms of Hatta'a group or the reaction factor is also proposed.The results are limited to packed columns with liquid as the dispersed and gas as the continuous phase operated counter-currently below the loading point.     

FEM simulation of effect of mould wall thickness on low alloy steel ingot solidification

Effect of increasing mould wall thickness on quality of low alloy square steel ingot of 40cmd8 grade (AISI P20) and of 4 t weight were studied by comparing three cases with the help of FEM simulation. Solidification simulation software THERCAST was used which could predict fluid flow, temperature, solidification, piping and centreline porosity for the cast ingot. With increased mould wall thickness fluid flow was not much affected. Heat transfer was retarded with increased mould wall thickness which delayed the solidification. Solidification profiles were with thin mushy zone and wide shaped which has lesser chances of dendrites bridging and helps in avoiding central porosity. Piping and porosity were predicted based on Niyama criteria. It was seen that porosity in the ingot centre were decreased with increased mould wall thickness. Optimal mould wall thickness could be obtained for square ingot of low alloy steel grade.