A study on finite element of pre damaged stress concentration factor for a composite laminate member with central circular

The study investigates the pre damaged stress concentration factor (SCF) for a composite laminate member (CLM) with central circular hole subjected to tensile loading. The presence of holes yields high stress concentrations in the structural members termed as stress raiser and often regarded as an important design deriver. The pre damaged SCF refers to the stress concentrations within elastic (undamaged) range of the CLM prior to the failure initiation. The traditional experimental and analytical methods for the estimation of SCF offer macro level behaviour which is not considered appropriate for CLM where lamina by lamina behaviour is more significant. A meso level finite element (FE) model is presented to capture the lamina by lamina influence on the overall SCF for a CLM using commercial software Abaqus. The paper deals with the fundamental influencing factors such as laminae orientation effect, stress distribution effect around periphery of the hole, decaying effect and ligament effect on SCF for CLM. Analytical models have been formulated to validate the FE models. The results of FE models have been found in close agreement with the analytical results.     

Functionalization of Magnetite Nanoparticles as Oil Spill Collector

In the present study, a new magnetic powder based on magnetite can be used as a petroleum crude oil collector. Amidoximes based on rosin as a natural product can be prepared from a reaction between hydroxylamine and rosin/acrylonitrile adducts. The produced rosin amidoximes were used as capping agents for magnetite nanoparticles to prepare hydrophobic coated magnetic powders. A new class of monodisperse hydrophobic magnetite nanoparticles was prepared by a simple and inexpensive co-precipitation method. Iron ions and iodine were prepared by the reaction between ferric chloride and potassium iodide. The structure and morphology of magnetite capped with rosin amidoxime were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), zeta potential, thermogravimetric analysis (TGA) and dynamic light scattering (DLS). The magnetic properties were determined from vibrating sample magnetometer (VSM) analyses. These prepared magnetite nanoparticles were tested as bioactive nanosystems and their antimicrobial effects were investigated. The prepared nanomaterials were examined as a crude oil collector using magnetic fields. The results show promising data for the separation of the petroleum crude oil from aqueous solution in environmental pollution cleanup.     

Experimental and numerical study of heat transfer in horizontal concentric annulus containing phase change material

In the present research work, solid–liquid phase change heat transfer was studied experimentally as well as numerically for paraffin wax encapsulated in the annulus of two coaxial circular cylinders with variable heat flux. Two‐dimensional mathematical model (Navier–Stokes equation) in terms of primitive variables has been formulated to study the melting characteristics of the phase change material (PCM). The finite volume method (FVM) and semi‐implicit, that is, SIMPLE scheme are applied to discretise the governing equations and track the solid–liquid moving front. From the comparison of experimental data and numerical simulation, it is evident that the convective heat transfer is dominant in melting phase. From the computational results it is also observed that both eccentricity and the variation in the angle of inclination of the eccentricity plays an important role for the net circulation of the molten phase as well as the thermal flux at the inner surface of the annulus.     

Miscibility of polystyrene with poly(ethylene oxide) and poly(ethylene glycol)

The intrinsic viscosity of polystyrene–poly(ethylene oxide) (PS–PEO) and PS–poly(ethylene glycol) (PEG) blends have been measured in benzene as a function of blend composition for various molecular weights of PEO and PEG at 303.15 K. The compatibility of polymer pairs in solution were determined on the basis of the interaction parameter term, Δb, and the difference between the experimental and theoretical weight-average intrinsic viscosities of the two polymers, Δ[η]. The theoretical weight-average intrinsic viscosities were calculated by interpolation of the individual intrinsic viscosities of the blend components. The compatibility data based on [η] determined by a single specific viscosity measurement, as a quick method for the determination of the intrinsic viscosity, were compared with that obtained from [η] determined via the Huggins equation. The effect of molecular weights of the blend components and the polymer structure on the extent of compatibility was studied. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1471–1482, 1998     

AC conductivity and dielectric measurements of bulk magnesium phthalocyanine (MgPc)

The AC conductivity, σ_ac(ω) for bulk magnesium phthalocyanine (MgPc) in the form of compressed pellet in the frequency range of 1–500 kHz and in a temperature range of 303–443 K with evaporated ohmic Au electrodes have been investigated. The frequency dependence of the impedance spectra plotted in the complex plane shows semicircles. The Cole–Cole diagrams have been used to determine the DC conductivity. The AC conductivity, σ_ac(ω), is found to vary as ω^s in the frequency range of 1–500 kHz. At high range of frequency, s < 1 and it decreases with increasing the temperature. The variation of s with temperature suggests that the AC conduction is due to the correlated barrier hopping (CBH). The dielectric constant, ′, and dielectric loss, ″, for bulk MgPc were decreased with increasing frequency and increased with increasing temperature.     

New epoxy resins based on recycled poly(ethylene terephthalate) as organic coatings

Glycolysis of poly(ethylene terephthalate), PET, waste using trimethylol propane (TMP), triethanolamine (TEA), diethylene glycol (DEG) and diethanolamine (DEA) was used to produce suitable hydroxy-oligomers for epoxy. The glycolyzed products were reacted with epichlorohydrine to prepare a series of di- and tetraglycidyl epoxy resins with different molecular weights. The glycolysis was carried out in presence of manganese acetate as a catalyst at normal and high pressure in presence and absence of xylene at 210 °C. The produced resins were cured with different mole ratios of 1-(2-amino ethyl) piprazine as curing agent at room temperature. The mechanical properties of the cured epoxy resins were evaluated. The chemical resistances of the cured resins were evaluated through salt spray resistance, hot water, solvents, acid and alkali resistance measurements. The data indicate that the cured epoxy resins based on glycolyzed oligomer of PET and DEA have excellent chemical resistances as organic coatings among other cured resins.     

Chemical composition,adulteration, total microbial load,and heavy metal in raw milk samples collected from dairy farms and urban areas in Lahore District,Pakistan

The present study evaluated raw milk samples from dairy farms and urban areas in Lahore District, Pakistan, for the measurement of chemical composition, presence of adulterants, total microbial, and heavy metals loads. Measurements of chemical composition and physicochemical properties of the raw milk samples collected from urban areas showed the following mean values of 2.76 ± 0.29, 2.62 ± 0.18, 1.27 ± 0.08, 7.13 ± 0.30, 6.46 ± 0.26, and 0.47 ± 0.02 for lactose, fat, protein, total solids, pH, and ash, respectively, while milk samples collected from dairy farms achieved the mean values of 4.82 ± 0.32, 5.02 ± 0.39, 3.36 ± 0.18, 13.19 ± 0.66, 6.67 ± 0.27, and 0.75 ± 0.05 for lactose, fat, protein, total solids, pH, and ash, respectively. Mean values of total plate count were 5.21 ± 0.28 CFU/ml for urban areas raw milk samples and 4.67 ± 0.27 CFU/ml for the dairy farm milk samples. Heavy metal mean concentrations for Pb, Cd, Cu, Zn, and Ni in urban areas milk samples from milk shop were 0.024 ± 0.005, 0.021 ± 0.006, 1.22 ± 0.25, 2.42 ± 0.57, and 0.044 ± 0.006 ppm, respectively. Conclusively, strategies should be adopted in order to prevent the heavy metal contamination in milk to further minimizes the health risks associated with heavy metal consumption.     

Fission MOLY production at PARR-1 using LEU plate type target

Neutronic analyses and depletion calculations have been performed for the production of ⁹⁹Mo at PARR-1. Analysis has been performed with 20% enriched ²³⁵U target bearing plate type aluminized fuel (U-Al). Target (target holder and fuel plates) design contains three fuel plates and two aluminum dummy plates. Neutronic calculations were carried out for core at the beginning of equilibrium cycle of Pakistan Research Reactor-1 (PARR-1). Target analysis was performed by irradiating it at a location of maximum thermal flux available in the core. For this purpose, irradiation was performed at five different axial planes of the central water box facility. Thermal neutron flux profiles were also studied at different axial positions in available irradiation locations. Computer code WIMSD/4, a transport theory lattice code was employed for the generation of 10 group microscopic cross-sections. Diffusion theory code CITATION was utilized for three-dimensional modeling of the core. It was observed that from reactivity point of view, insertion or removal of target from the core will not affect the safety of reactor. Maximum heat flux in the target would be 102.68 W/cm² which is below the point of onset of nucleate boiling. However, forced flow is required to avoid initiation of nucleate boiling. The computer code ORIGEN2 was employed for depletion calculations. Analysis was performed for 100 Ci activity of ⁹⁹Mo. After 100 days decay, waste activity will be less than 1 Ci and it will not pose any problem for handling radioactive waste.