Scholarly

Ageing Assessment of Insulation Systems by Absorption/Resorption Currents

Year: 2009 Volume: 3 Issue: 1 60 - 66 Pages

Abstract: Degradation of polymeric insulation systems of electrical equipments increases the space charge density and the concentration of electrical dipoles. By consequence, the maximum values and the slopes of absorption/resorption (A/R) currents can change with insulation systems ageing. In this paper, an analysis of the nature of the A/R currents and the importance of their components, especially the polarization current and the current given by the space charge, is presented. The experimental study concerns the A/R currents measurements of plane samples (made from CALMICAGLAS tapes), virgin and thermally accelerated aged. The obtained results show that the ageing process produces an increase of the values and a decrease of shapes of the A/R currents. Finally, the possibility of estimating insulations ageing state and lifetime from A/R currents measurements is discussed.

Flow Visualization and Characterization of an Artery Model with Stenosis

Year: 2011 Volume: 5 Issue: 12 656 - 659 Pages

Abstract: Cardiovascular diseases, principally atherosclerosis, are responsible for 30% of world deaths. Atherosclerosis is due to the formation of plaque. The fatty plaque may be at risk of rupture, leading typically to stroke and heart attack. The plaque is usually associated with a high degree of lumen reduction, called a stenosis.It is increasingly recognized that the initiation and progression of disease and the occurrence of clinical events is a complex interplay between the local biomechanical environment and the local vascular biology. The aim of this study is to investigate the flow behavior through a stenosed artery. A physical experiment was performed using an artery model and blood analogue fluid. An axisymmetric model constructed consists of contraction and expansion region that follow a mathematical form of cosine function. A 30% diameter reduction was used in this study. The flow field was measured using particle image velocimetry (PIV). Spherical particles with 20μm diameter were seeded in a water-glycerol-NaCl mixture. Steady flow Reynolds numbers are 250. The area of interest is the region after the stenosis where the flow separation occurs. The velocity field was measured and the velocity gradient was investigated. There was high particle concentration in the recirculation zone. High velocity gradient formed immediately after the stenosis throat created a lift force that enhanced particle migration to the flow separation area.

Experimental Investigation on Solid Concentration in Gas-Solid Circulating Fluidized Bed for Methanol-to-Olefins Process

Year: 2010 Volume: 4 Issue: 8 482 - 488 Pages

Abstract: Methanol-to-olefins coupled with transformation of coal or natural gas to methanol gives an interesting and promising way to produce ethylene and propylene. To investigate solid concentration in gas-solid fluidized bed for methanol-to-olefins process catalyzed by SAPO-34, a cold model experiment system is established in this paper. The system comprises a gas distributor in a 300mm internal diameter and 5000mm height acrylic column, the fiber optic probe system and series of cyclones. The experiments are carried out at ambient conditions and under different superficial gas velocity ranging from 0.3930m/s to 0.7860m/s and different initial bed height ranging from 600mm to 1200mm. The effects of radial distance, axial distance, superficial gas velocity, initial bed height on solid concentration in the bed are discussed. The effects of distributor shape and porosity on solid concentration are also discussed. The time-averaged solid concentration profiles under different conditions are obtained.

Assessment of the Influence of External Earth Terrain at Construction of the Physicmathematical Models or Finding the Dynamics of Pollutants' Distribution in Urban Atmosphere

Year: 2012 Volume: 6 Issue: 7 722 - 728 Pages

Abstract: There is a complex situation on the transport environment in the cities of the world. For the analysis and prevention of environmental problems an accurate calculation hazardous substances concentrations at each point of the investigated area is required. In the turbulent atmosphere of the city the wellknown methods of mathematical statistics for these tasks cannot be applied with a satisfactory level of accuracy. Therefore, to solve this class of problems apparatus of mathematical physics is more appropriate. In such models, because of the difficulty as a rule the influence of uneven land surface on streams of air masses in the turbulent atmosphere of the city are not taken into account. In this paper the influence of the surface roughness, which can be quite large, is mathematically shown. The analysis of this problem under certain conditions identified the possibility of areas appearing in the atmosphere with pressure tending to infinity, i.e. so-called "wall effect".

Groundwater Contamination due to Bhalaswa Landfill Site in New Delhi

Year: 2009 Volume: 3 Issue: 3 155 - 159 Pages

Abstract: Sampling and analysis of leachate from Bhalaswa landfill and groundwater samples from nearby locations, clearly indicated the likely contamination of groundwater due to landfill leachate. The results of simulation studies carried out for the migration of Chloride from landfill shows that the simulation results are in consonance with the observed concentration of Chloride in the vicinity of landfill facility. The solid waste disposal system presently being practiced in Delhi consists of mere dumping of wastes generated, at three locations Bhalaswa, Ghazipur, and Okhla without any regard to proper care for the protection of surrounding environment. Bhalaswa landfill site in Delhi, which is being operated as a dump site, is expected to become cause of serious groundwater pollution in its vicinity. The leachate from Bhalaswa landfill was found to be having a high concentration of chlorides, as well as DOC, COD. The present study was undertaken to determine the likely concentrations of principle contaminants in the groundwater over a period of time due to the discharge of such contaminants from landfill leachates to the underlying groundwater. The observed concentration of chlorides in the groundwater within 75m of the radius of landfill facility was found to be in consonance with the simulated concentration of chloride in groundwater considering one dimensional transport model, with finite mass of contaminant source. Governing equation of contaminant transport involving advection and diffusion-dispersion was solved in matlab7.0 using finite difference method.

Amberlite XAD-4 Functionalized with 1-amino-2-naphthole for Determination and Preconcentration of Copper (II) in Aqueous Solution by Flame Atomic Absorption Spectrometry

Year: 2010 Volume: 4 Issue: 7 439 - 441 Pages

Abstract: A new chelating resin is prepared by coupling Amberlite XAD-4 with 1-amino-2-naphthole through an azo spacer. The resulting sorbent has been characterized by FT-IR, elemental analysis and thermogravimetric analysis (TGA) and studied for preconcentrating of Cu (II) using flame atomic absorption spectrometry (FAAS) for metal monitoring. The optimum pH value for sorption of the copper ions was 6.5. The resin was subjected to evaluation through batch binding of mentioned metal ion. Quantitative desorption occurs instantaneously with 0.5 M HNO3. The sorption capacity was found 4.8 mmol.g-1 of resin for Cu (II) in the aqueous solution. The chelating resin can be reused for 10 cycles of sorption-desorption without any significant change in sorption capacity. A recovery of 99% was obtained the metal ions with 0.5 M HNO3 as eluting agent. The method was applied for metal ions determination from industrial waste water sample.

Antioxydant and Antibacterial Activity of Alkaloids and Terpenes Extracts from Euphorbia granulata

Year: 2013 Volume: 7 Issue: 3 186 - 189 Pages

Abstract: In order to enhance the knowledge of certain phytochemical Algerian plants that are widely used in traditional medicine and to exploit their therapeutic potential in modern medicine, we have done a specific extraction of terpenes and alkaloids from the leaves of Euphorbia granulata to evaluate the antioxidant and antibacterial activity of this extracts. After the extraction it was found that the terpene extract gave the highest yield 59.72% compared with alkaloids extracts. The disc diffusion method was used to determine the antibacterial activity against different bacterial strains: Escherichia coli (ATCC25922), Pseudomonas aeruginosa (ATCC27853) and Staphylococcus aureus (ATCC25923). All extracts have shown inhibition of growth bacteria. The different zones of inhibition have varied from (7 -10 mm) according to the concentrations of extract used. Testing the antiradical activity on DPPH-TLC plates indicated the presence of substances that have potent anti-free radical. As against, the BC-TLC revealed that only terpenes extract which was reacted positively. These results can validate the importance of Euphorbia granulata in traditional medicine.

The Effect of Guanidine Hydrochloride on Phase Diagram of PEG- Phosphate Aqueous Two-Phase System

Year: 2007 Volume: 1 Issue: 5 50 - 54 Pages

Abstract: This report focus on phase behavior of polyethylene glycol (PEG)4000/ phosphate/ guanidine hydrochloride/ water system at different guanidine hydrochloride concentrations and pH. The binodal of the systems was displaced toward higher concentrations of the components with increasing guanidine hydrochloride concentrations. The partition coefficient of guanidine hydrochloride was near unity and increased with decreasing pH and increasing PEG/salt (%w/w) ratio.

Simulation of a Process Design Model for Anaerobic Digestion of Municipal Solid Wastes

Year: 2011 Volume: 5 Issue: 8 694 - 699 Pages

Abstract: Anaerobic Digestion has become a promising technology for biological transformation of organic fraction of the municipal solid wastes (MSW). In order to represent the kinetic behavior of such biological process and thereby to design a reactor system, development of a mathematical model is essential. Addressing this issue, a simplistic mathematical model has been developed for anaerobic digestion of MSW in a continuous flow reactor unit under homogeneous steady state condition. Upon simulated hydrolysis, the kinetics of biomass growth and substrate utilization rate are assumed to follow first order reaction kinetics. Simulation of this model has been conducted by studying sensitivity of various process variables. The model was simulated using typical kinetic data of anaerobic digestion MSW and typical MSW characteristics of Kolkata. The hydraulic retention time (HRT) and solid retention time (SRT) time were mainly estimated by varying different model parameters like efficiency of reactor, influent substrate concentration and biomass concentration. Consequently, design table and charts have also been prepared for ready use in the actual plant operation.

Antidiabetic and Antioxidative Activities of Butyrolactone I from Aspergillus terreus MC751

Year: 2012 Volume: 6 Issue: 10 883 - 888 Pages

Abstract: The bioassay-guided isolation and purification of an ethyl acetate extract of Aspergillus terreus MC751 led to the characterization of butyrolactone I as an antidiabetic and antioxidant. The antidiabetic activity of butyrolactone I was evaluated by α- glucosidase and α-amylase inhibition assays. Butyrolactone I demonstrated significant concentration-dependent, mixed-type inhibitory activity against yeast α-glucosidase with an IC50 of 54μM. However, the compound exhibited less activity against rat intestinal α-glucosidase and α-amylase. This is the first report on α-glucosidase inhibitory activity of butyrolactone I. The antioxidative activity of butyrolactone I was evaluated based on scavenging effects on 1,1- diphenyl-2-picrylhydrazyl (DPPH) (IC50 =51 μM) and hydrogen peroxide (IC50= 141 μM) radicals as well as a reducing power assay. The results suggest that butyrolactone I is a promising antidiabetic as well as antioxidant and should be considered for clinical trials.

Preparation of Polylactic Acid Graft Polyvinyl Acetate Compatibilizers for 50/50 Starch/PLLA Blending

Year: 2012 Volume: 6 Issue: 5 439 - 441 Pages

Abstract: Polylactic acid-g-polyvinyl acetate (PLLA-g-PVAc) was used as a compatibilizer for 50/50 starch/PLLA blend. PLLA-g- PVAc with different mol% of PVAc contents were prepared by grafting PVAc onto PLLA backbone via free radical polymerization in solution process. Various conditions such as type and the amount of initiator, monomer concentration, polymerization time and temperature were studied. Results showed that the highest mol% of PVAc grafting (16 mol%) was achieved by conducting graft copolymerization in toluene at 110°C for 10 h using DCP as an initiator. Chemical structure of the PVAc grafted PLLA was confirmed by 1H NMR. Blending of modified starch and PLLA in the presence compatibilizer with different amounts and mol% PVAc was acquired using internal mixer at 160°C for 15 min. Effects of PVAc content and the amount of compatibilizer on mechanical properties of polymer blend were studied. Results revealed that tensile strength and tensile modulus of polymer blend with higher PVAc grafting content compatibilizer showed better properties than that of lower PVAc grafting content compatibilizer. The amount of compatibilizer was found optimized in the range of 0.5-1.0 Wt% depending on the mol% PVAc.

The Influence of Surface Potential on the Kinetics of Bovine Serum Albumin Adsorption on a Biomedical Grade 316LVM Stainless Steel Surface

Year: 2011 Volume: 5 Issue: 5 406 - 412 Pages

Abstract: Polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) in combination with electrochemistry, was employed to study the influence of surface charge (potential) on the kinetics of bovine serum albumin (BSA) adsorption on a biomedical-grade 316LVM stainless steel surface is discussed. The BSA adsorption kinetics was found to greatly depend on the surface potential. With an increase in surface potential towards more negative values, both the BSA initial adsorption rate and the equilibrium (saturated) surface concentration also increased. Both effects were explained on the basis of replacement of well-ordered water molecules at the 316LVM / solution interface, i.e. by the increase in entropy of the system.

Numerical Simulation of the Effects of Nanofluid on a Heat Pipe Thermal Performance

Year: 2012 Volume: 6 Issue: 8 1493 - 1499 Pages

Abstract: This research aims at modeling and simulating the effects of nanofluids on cylindrical heat pipes thermal performance using the ANSYS-FLUENT CFD commercial software. The heat pipe outer wall temperature distribution, thermal resistance, liquid pressure and axial velocity in presence of suspended nano-scaled solid particle (i.e. Cu, Al2O3 and TiO2) within the fluid (water) were investigated. The effect of particle concentration and size were explored and it is concluded that the thermal performance of the heat pipe is improved when using nanofluid as the system working fluid. Additionally, it was observed that the thermal resistance of the heat pipe drops as the particle concentration level increases and particle radius decreases.

The Effect of Unburned Carbon on Coal Fly Ash toward its Adsorption Capacity for Methyl Violet

Year: 2013 Volume: 7 Issue: 6 385 - 388 Pages

Abstract: Coal fly ash (CFA) generated by coal-based thermal power plants is mainly composed of quartz, mullite, and unburned carbon. In this study, the effect of unburned carbon on CFA toward its adsorption capacity was investigated. CFA with various carbon content was obtained by refluxing it with sulfuric acid having various concentration at various temperature and reflux time, by heating at 400-800°C, and by sieving into 100-mesh in particle size. To evaluate the effect of unburned carbon on CFA toward its adsorption capacity, adsorption of methyl violet solution with treated CFA was carried out. The research shows that unburned carbon leads to adsorption capacity decrease. The highest adsorption capacity of treated CFA was found 5.73 x 10-4mol.g-1.

C-V Characterization and Analysis of Temperature and Channel Thickness Effects on Threshold Voltage of Ultra-thin SOI MOSFET by Self-Consistent Model

Year: 2010 Volume: 4 Issue: 9 1362 - 1367 Pages

Abstract: The threshold voltage and capacitance voltage characteristics of ultra-thin Silicon-on-Insulator MOSFET are greatly influenced by the thickness and doping concentration of the silicon film. In this work, the capacitance voltage characteristics and threshold voltage of the device have been analyzed with quantum mechanical effects using the Self-Consistent model. Reduction of channel thickness and adding doping impurities cause an increase in the threshold voltage. Moreover, the temperature effects cause a significant amount of threshold voltage shift. The temperature dependence of threshold voltage has also been observed with Self- Consistent approach which are well supported from experimental performance of practical devices.

Selective Separation of Lead and Mercury Ions from Synthetic Produced Water via a Hollow Fiber Supported Liquid Membrane

Year: 2012 Volume: 6 Issue: 8 714 - 719 Pages

Abstract: A double module hollow fiber supported liquid membrane (HFSLM) was applied to selectively separate lead and mercury ions from dilute synthetic produced water. The experiments were investigated on several variables: types of extractants (D2EHPA, Cyanex 471, Aliquat 336, and TOA), concentration of the selected extractant and operating time. The results clearly showed that the double module HFSLM could selectively separate Pb(II) and Hg(II) in feed solution at a very low concentration to less than the regulatory discharge limit of 0.2 and 0.005 mg/L issued by the Ministry of Industry and the Ministry of Natural Resource Environment, Thailand. The highest extractions of lead and mercury ions from synthetic produced water were 96% and 100% using 0.03 M D2EHPA and 0.06 M Aliquat 336 as the extractant for the first and second modules.

Hydrogen Sulphide Removal Using a Novel Biofilter Media

Year: 2010 Volume: 4 Issue: 2 182 - 185 Pages

Abstract: Air emissions from waste treatment plants often consist of a combination of Volatile Organic Compounds (VOCs) and odors. Hydrogen sulfide is one of the major odorous gases present in the waste emissions coming from municipal wastewater treatment facilities. Hydrogen sulfide (H2S) is odorous, highly toxic and flammable. Exposure to lower concentrations can result in eye irritation, a sore throat and cough, shortness of breath, and fluid in the lungs. Biofiltration has become a widely accepted technology for treating air streams containing H2S. When compared with other nonbiological technologies, biofilter is more cost-effective for treating large volumes of air containing low concentrations of biodegradable compounds. Optimization of biofilter media is essential for many reasons such as: providing a higher surface area for biofilm growth, low pressure drop, physical stability, and good moisture retention. In this work, a novel biofilter media is developed and tested at a pumping station of a municipality located in the United Arab Emirates (UAE). The media is found to be very effective (>99%) in removing H2S concentrations that are expected in pumping stations under steady state and shock loading conditions.

Urban Air Pollution – Trend and Forecasting of Major Pollutants by Timeseries Analysis

Year: 2009 Volume: 3 Issue: 3 151 - 154 Pages

Abstract: The Bangalore City is facing the acute problem of pollution in the atmosphere due to the heavy increase in the traffic and developmental activities in recent years. The present study is an attempt in the direction to assess trend of the ambient air quality status of three stations, viz., AMCO Batteries Factory, Mysore Road, GRAPHITE INDIA FACTORY, KHB Industrial Area, Whitefield and Ananda Rao Circle, Gandhinagar with respect to some of the major criteria pollutants such as Total Suspended particular matter (SPM), Oxides of nitrogen (NOx), and Oxides of sulphur (SO2). The sites are representative of various kinds of growths viz., commercial, residential and industrial, prevailing in Bangalore, which are contributing to air pollution. The concentration of Sulphur Dioxide (SO2) at all locations showed a falling trend due to use of refined petrol and diesel in the recent years. The concentration of Oxides of nitrogen (NOx) showed an increasing trend but was within the permissible limits. The concentration of the Suspended particular matter (SPM) showed the mixed trend. The correlation between model and observed values is found to vary from 0.4 to 0.7 for SO2, 0.45 to 0.65 for NOx and 0.4 to 0.6 for SPM. About 80% of data is observed to fall within the error band of ±50%. Forecast test for the best fit models showed the same trend as actual values in most of the cases. However, the deviation observed in few cases could be attributed to change in quality of petro products, increase in the volume of traffic, introduction of LPG as fuel in many types of automobiles, poor condition of roads, prevailing meteorological conditions, etc.

Agent-based Simulation for Blood Glucose Control in Diabetic Patients

Year: 2009 Volume: 3 Issue: 9 228 - 235 Pages

Abstract: This paper employs a new approach to regulate the blood glucose level of type I diabetic patient under an intensive insulin treatment. The closed-loop control scheme incorporates expert knowledge about treatment by using reinforcement learning theory to maintain the normoglycemic average of 80 mg/dl and the normal condition for free plasma insulin concentration in severe initial state. The insulin delivery rate is obtained off-line by using Qlearning algorithm, without requiring an explicit model of the environment dynamics. The implementation of the insulin delivery rate, therefore, requires simple function evaluation and minimal online computations. Controller performance is assessed in terms of its ability to reject the effect of meal disturbance and to overcome the variability in the glucose-insulin dynamics from patient to patient. Computer simulations are used to evaluate the effectiveness of the proposed technique and to show its superiority in controlling hyperglycemia over other existing algorithms

Quantification of Peptides based on Isotope Dilution Surface Enhanced Raman Scattering

Year: 2012 Volume: 6 Issue: 3 199 - 202 Pages

Abstract: This study aims to demonstrate the quantification of peptides based on isotope dilution surface enhanced Raman scattering (IDSERS). SERS spectra of phenylalanine (Phe), leucine (Leu) and two peptide sequences TGQIFK (T13) and YSFLQNPQTSLCFSESIPTPSNR (T6) as part of the 22-kDa human growth hormone (hGH) were obtained on Ag-nanoparticle covered substrates. On the basis of the dominant Phe and Leu vibrational modes, precise partial least squares (PLS) prediction models were built enabling the determination of unknown T13 and T6 concentrations. Detection of hGH in its physiological concentration in order to investigate the possibility of protein quantification has been achieved.

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