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91.
K. N. Seetharamu R. Paragasam Ghulam A. Quadir Z. A. Zainal B. Sathya Prasad T. Sundararajan 《Sadhana》2001,26(1-2):103-120
The process of solidification process is complex in nature and the simulation of such process is required in industry before
it is actually undertaken. Finite element method is used to simulate the heat transfer process accompanying the solidification
process. The metal and the mould along with the air gap formation is accounted in the heat transfer simulation. Distortion
of the casting is caused due to non-uniform shrinkage associated with the process. Residual stresses are induced in the final
castings. Simulation of the shrinkage and the thermal stresses are also carried out using finite element methods. The material
behaviour is considered as visco-plastic. The simulations are compared with available experimental data and the comparison
is found to be good. Special considerations regarding the simulation of solidification process are also brought out.
An erratum to this article is available at . 相似文献
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94.
Jing Huey Khor Widad Ismail Mohammed I. Younis M. K. Sulaiman Mohammad Ghulam Rahman 《Wireless Personal Communications》2011,59(1):17-26
This paper focuses on the security and privacy threats being faced by the low-cost RFID communication system, the most challenging
of which relate to eavesdropping, impersonation, and tag cloning problems. The security issues can be improved and solved
by utilizing both prevention and detection strategies. Prevention technique is needed since it offers resistance capabilities
toward eavesdroppers and impersonators. Detection technique is vital to minimize the negative effects of tag cloning threats.
This paper proposes the use of both prevention and detection techniques to make RFID communication more secure. Lightweight
cryptographic algorithm, which conforms to the EPC Class-1 Generation-2 standard, is used in the proposed mutual authentication
protocol for RFID system to raise security levels. In addition, electronic fingerprinting system is deployed in the proposed
solution as a detection method to distinguish counterfeit and legitimate tags. 相似文献
95.
Waheed S. Khan Zahid Usman Ghulam Nabi Zulfiqar Ali Niaz Ahmad Niaz 《Materials Research Bulletin》2011,46(12):2261-2265
Metallic zinc layered polyhedral microparticles have been fabricated by thermal evaporation and condensation technique using zinc as precursor at 750 °C for 120 min and NH3 as a carrier gas. The zinc polyhedral microparticles with oblate spherical shape are observed to be 2-9 μm in diameter along major axes and 1-7 μm in thickness along minor axes. The structural, compositional and morphological characterizations were performed by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). A vapour-solid (VS) mechanism based growth model has been proposed for the formation of Zn microparticles. Room temperature photoluminescence (PL) emission spectrum of the product exhibited a strong emission band at 369 nm attributed to the radiative recombination of electrons in the s, p conduction band near Fermi surface and the holes in the d bands generated by the optical excitation. 相似文献
96.
This study appraised cadmium (Cd) toxicity stress in wetland plant Juncus effusus, and explored its potential for Cd phytoextraction through chelators (citric acid and EDTA). Cadmium altered morphological and physiological attributes of J. effusus as reflected by growth retardation. Citric acid in the presence of 100 μM Cd significantly countered Cd toxicity by improving plant growth. Elevated Cd concentrations reduced translocation factor that was increased under application of both chelators. Citric acid enhanced Cd accumulation, while EDTA reduced its uptake. Cadmium induced oxidative stress modified the antioxidative enzyme activity. Both levels of citric acid (2.5 and 5.0 mM) and lower EDTA concentration (2.5 mM) helped plants to overcome oxidative stress by enhancing their antioxidative enzyme activities. Cadmium damaged the root cells through cytoplasmic shrinkage and metal deposition. Citric acid restored structure and shape of root cells and eliminated plasmolysis; whereas, EDTA exhibited no positive effect on it. Shoot cells remained unaffected under Cd treatment alone or with citric acid except for chloroplast swelling. Only EDTA promoted starch accumulation in chloroplast reflecting its negative impact on cellular structure. It concludes that Cd and EDTA induce structural and morphological damage in J. effusus; while, citric acid ameliorates Cd toxicity stress. 相似文献
97.
Ghulam Abbas 《Drug development and industrial pharmacy》2013,39(12):2026-2037
AbstractRaft is an emerging drug delivery system, which is suitable for controlled release drug delivery and targeting. The present study aimed to evaluate the physico-chemical properties of raft, in vitro release of pantoprazole sodium sesquihydrate and conduct bioavailability studies. Box behnken design was used with three independent and dependent variables. Independent variables were sodium alginate (X1), pectin (X2) and hydroxypropyl methyl cellulose K100M (X3) while dependent variables were percentage drug release at 2 (Y2), 4 (Y4) and 8?h (Y8). The developed rafts were evaluated by their physical and chemical properties. Fourier transform infrared spectroscopy and differential scanning calorimetry were used to study the chemical interaction and thermal behaviour of drug with polymers. Alginate and pectin contents of R9 formulation were 99.28% and 97.29%, respectively, and acid neutralization capacity was 8.0. R9 formulation showed longer duration of neutralization and nature of raft was absorbent. The raft of R9 formulation showed 98.94% release of PSS at 8?h in simulated gastric fluid. Fourier transform infrared spectroscopy showed no chemical interaction and differential scanning calorimetry indicated endothermic peaks at 250?°C for pantoprazole sodium sesquihydrate. tmax for the test and reference formulations were 8?±?2.345?h and 8?±?2.305?h, respectively. Cmax of test and reference formulations were 46.026?±?0.567?µg/mL and 43.026?±?0.567?µg/mL, respectively. AUC(0-t) of the test and reference formulations were 472.115?±?3.467?µg?×?h/mL and 456.105?±?2.017?µg?×?h/mL, respectively. Raft forming system successfully delivered the drug in controlled manner and improved the bioavailability of drugs. 相似文献
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99.
Ghulam Destgeer Anas Alazzam Hyung Jin Sung 《Journal of Mechanical Science and Technology》2016,30(9):3945-3952
In this study, we have demonstrated a particle separation device taking advantage of the high frequency sound waves. The sound waves, in the form of surface acoustic waves, are produced by an acoustofluidic platform built on top of a piezoelectric substrate bonded to a microfluidic channel. The particles’ mixture, pumped through the microchannel, is focused using a sheath fluid. A Travelling surface acoustic wave (TSAW), propagating normal to the flow, interacts with the particles and deflects them from their original path to induce size-based separation in a continuous flow. We initially started the experiment with 40 MHz TSAWs for deflecting 10 µm diameter polystyrene particles but failed. However, larger diameter particles (~ 30 µm) were successfully deflected from their streamlines and separated from the smaller particles (~ 10 µm) using TSAWs with 40 MHz frequency. The separation of smaller diameter particles (3, 5 and 7 µm) was also achieved using an order of magnitude higher-frequency (~ 133 MHz) TSAWs. 相似文献
100.
In recent studies, much attention has been given to nanofluids suggesting that adding nanoparticles in base fluids offers a higher heat transfer rate compared with conventional fluids. This study is based on the numerical investigation of different types of nanofluids, consisting of CuO (50 nm), SiO2 (40 nm), and Al2O3 (15 nm) nanoparticles at different volume concentrations. Several simulations were performed from low to high Reynolds numbers, corresponding to laminar and turbulent flow regimes using ANSYS-Fluent CFD solver. Results suggest that under a laminar flow regime with the same Reynolds number of 2000, CuO-based nanofluids perform better as compared with SiO2 and Al2O3-based nanofluids with Nusselt number (Nu) having percentage increase of 90% and 60% comparing with SiO2- and Al2O3-based nanofluids, respectively. However, at higher Reynolds numbers when the flow is turbulent, Al2O3-based nanofluids demonstrate better performance having a percentage increase in Nusselt numbers equal to 40% and 23% as compared with CuO and SiO2-based nanofluids respectively under the same Reynolds number of 15,000. This implies that turbulence has a significant effect on heat transfer rate, and is not only related to thermal conductivity. This study will help in designing more compact cooling systems for engines and the internal environment of motor vehicles. 相似文献