Dynamic Properties of Kinetic Spin-3/2 Ising Ferromagnetic Model in the Presence of the Crystal and External Oscillating Magnetic Fields

The kinetic spin-3/2 Ising system in the presence of crystal and external oscillating magnetic fields on the triangular lattice (TL) is examined within the mean-field approximation and the Glauber-type stochastic dynamics, namely dynamic mean-field approximation (DMFA). First, the dynamic equations describing the behavior of the system are derived for the TL. Then, the dynamic equations are solved numerically to obtain the dynamic hysteresis curves of the kinetic spin-3/2 Ising ferromagnetic system, which strongly depend on the Hamiltonian parameters. Moreover, the dynamic behaviors of the coercivity and remanent magnetizations are studied depending on the temperature, crystal field and frequency of the oscillating external magnetic field. Finally, the results are compared with some experimental and theoretical studies and a qualitatively good overall agreement is observed     

Dynamic Magnetic Hysteresis Behaviors in a Mixed Spin (3/2, 2) Bilayer System with Different Crystal-Field Interactions

Dynamic magnetic hysteresis (DMH) behaviors of the mixed spin-3/2 and spin-2 Ising bilayer system with different crystal-field interactions on a two-layer square lattice is studied by the use of dynamic mean field calculations based on the Glauber-type stochastic. The hysteresis loops are obtained for different reduced temperatures (T), magnetic field amplitudes (h), frequencies (w) and interlayer coupling constants (J ₃). Influences of the T, h, w and J ₃ on the DMH properties are investigated. We also study the temperature, frequency and interlayer coupling interaction dependence of the coercive field and remanent magnetization. We compare our results with some theoretical and experimental works and observe a quantitatively good agreement with some theoretical and experimental results.     

The contact problem of a rigid stamp with friction on a functionally graded magneto-electro-elastic half-plane

We consider in this study the frictional sliding contact problem between a functionally graded magneto-electro-elastic material and a perfectly conducting rigid punch subjected to magneto-electro-mechanical loads. The problem is formulated under plane strain conditions. Using Fourier transform, the resulting plane magneto-electro-elasticity equations are converted analytically into three coupled singular integral equations in which the unknowns are the normal contact stress, the electric displacement and the magnetic induction. These integral equations are then solved numerically to obtain the distributions of the normal contact stress, electric displacement and magnetic induction at the surface of the graded medium. The main objective of this paper is to study the effect of the non-homogeneity parameter, the friction coefficient and the elastic, electric and magnetic coefficients on the surface contact pressure, electric displacement and magnetic induction distributions for the case of flat and circular punch profiles.     

Software development with imperfect information

Delivering software systems that fulfill all requirements of the stakeholders is very difficult, if not at all impossible. We consider the problem of coping with imperfect information, like interpreting incomplete requirement specifications or vagueness in decisions, one of the main reasons that makes software design difficult. We define a method for tracing design decisions under imperfect information. To model and compare requirements with estimations, we present fuzzy and stochastic techniques. This approach offers adequate decision support that can deal with imperfect information during software design. The approach is illustrated by a real-world example, based on a storm surge barrier system.     

Porous magnetic chelator support for albumin adsorption by immobilized metal affinity separation

Magnetic poly(2‐hydroxyethylmethacrylate) (mPHEMA) beads are modified by iminodiacetic acid (IDA) to implify the reactive groups and subsequent binding of Cu²⁺ ions to form metal chelate. mPHEMA beads, in the size range of 80–120 μm, were produced by a modified suspension polymerization technique. mPHEMA beads were characterized by swelling tests, electron spin resonance (ESR), FTIR, and scanning electron microscopy (SEM). Important results obtained in this study are as follows. The swelling ratio of mPHEMA beads was 34%. The presence of magnetite particles in the polymeric structure was confirmed by ESR. FTIR data confirmed that the magnetic polymer beads were modified with functional groups IDA. The mPHEMA beads have a spherical shape and porous structure. The effect of pH and concentration of human serum albumin (HSA), on the adsorption of HSA to the metal‐chelated magnetic beads, were examined in a batch reactor. Most importantly, the magnetic beads had little nonspecific adsorption for HSA (0.5 mg/g) before introducing IDA groups. Cu²⁺ chelation increased the HSA adsorption up to 28.4 mg/g. Adsorption behavior can be described at least approximately with the Langmuir equation. Regeneration of the metal‐chelated magnetic beads was easily performed with 1.0M NaSCN, pH 8.0, followed by washing with distilled water and reloading with Cu²⁺. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2501–2510, 2004     

Energy and exergy analysis of a ground-coupled heat pump system with two horizontal ground heat exchangers

In this paper we investigate of energetic and exergetic efficiencies of ground-coupled heat pump (GCHP) system as a function of depth trenches for heating season. The horizontal ground heat exchangers (HGHEs) were used and it were buried with in 1 m (HGHE1) and 2 m (HGHE2) depth trenches. The energy efficiency of GCHP systems are obtained to 2.5 and 2.8, respectively, while the exergetic efficiencies of the overall system are found to be 53.1% and 56.3%, respectively, for HGHE1 and HGHE2. The irreversibility of HGHE2 is less than of the HGHE1 as about 2.0%. The results show that the energetic and exergetic efficiencies of the system increase when increasing the heat source (ground) temperature for heating season. And the end of this study, we deal with the effects of varying reference environment temperature on the exergy efficiencies of HGHE1 and HGHE2. The results show that increasing reference environment temperature decreases the exergy efficiency in both HGHE1 and HGHE2.     

Biosorption of copper(II) by Marrubium globosum subsp. globosum leaves powder: effect of chemical pretreatment

The study was aimed at determining the effect of chemical pretreatment on copper(II) biosorption by Marrubium globosum subsp. globosum leaves. The uptake capacity of the biomass was increased by chemical pretreatment when compared with the raw biomass. The results of biosorption experiments, carried out at the conditions of 50 mg l(-1) initial metal concentration and pH 5.5, showed that pretreating the biomass with alkali solutions (laundry detergent, sodium hydroxide and sodium bicarbonate, 0.5 M) improved the biosorption capacity of biomass (45.90, 45.78 and 43.91%, respectively) compared with raw biomass. Pretreatment with sulfuric and nitric acid solutions, 0.5 M, increased the biosorption capacity of biomass by 11.82 and 10.18%, respectively, while there was no considerable change in the biosorption capacity of biomass (0.35%) after pretreatment with formic acid solution, 0.5 M. Furthermore, sodium chloride and calcium chloride, 0.5 M, pretreatments resulted in the improvement in biosorption capacity of biomass (31.38 and 26.69%, respectively). FT-IR analysis revealed that hydroxyl and carboxyl functional groups were mainly responsible for copper(II) biosorption.     

An investigation into ballistic performance and energy absorption capabilities of woven aramid fabrics

This paper presents an investigation regarding the ballistic performance of protection panels of different fabric ply numbers used in body armours. Twaron CT 710 type fabric layers of differing numbers are joined by using three stitch types to form the panels and then the panels are subjected to ballistic tests according to NIJ standards. Ballistic performance of the panels is determined by measuring trauma depth and trauma diameter. The energy absorbed by the fabric layers and the energy transmitted to the back of the fabric layers are determined from the trauma depth and trauma diameter values using a different approach. It is shown that the fabric ply number and stitching type have significant effects on ballistic properties and the effect of conditioning is limited.     

Calculating production rate of a flexible manufacturing module

This paper presents a closed form equation for calculating production rate of a flexible manufacturing module (FMM) which operates under stochastic conditions, including random machining times, random part loading and unloading times, and random pallet transfer times. Random operational conditions may arise due to the randomness in the variety of parts introduced into the system. The FMM consists of two machines, one pallet handling system, and a loading/unloading robot. The model and the resulting closed form equations allow the FMM designers and operation engineers select the most appropriate parameters for the maximum production output rate.     

Determining the dependence of colour values on yarn structure

The colour values of knitted cotton fabrics made from single and plied ring and compact yarns were investigated before and after dyeing. The fabric samples were knitted under the same constructional properties and then dyed with direct and reactive dyes. It was found that fabrics with ring yarns had high lightness and low chroma and colour strength values compared with fabrics with compact yarns. Also colour strength and colour difference values of dyed fabrics were assessed after increasing abrasion cycles (2500, 5000, 7500 and 10 000). The main changes in colour strength values were observed at 2500 abrasion cycles. The effect of abrasion on colour difference values of fabrics having ring yarns was more obvious than fabrics having compact yarns.