Showing papers by "Cochin University of Science and Technology published in 2009"
TL;DR: A survey using a questionnaire was conducted among 2536 employees in eight major accident hazard chemical industrial units in Kerala as discussed by the authors, where 75% of the data collected was subjected to principal component factor analysis with varimax rotation using SPSS program.
241 citations
TL;DR: In this paper, the microwave absorption, microwave reflection and EMI shielding properties of PANI-polyurethane (PANI-PU) composite were evaluated both at S-band and X-band frequencies.
228 citations
TL;DR: In this article, 1,2-glycerol carbonate was obtained from glycerol and carbon dioxide in methanol using 1.5% n Bu 2 SnO (dibutyltin(IV)oxide, 1 ) as a catalyst.
Abstract: Selectively 1,2-glycerol carbonate was obtained from glycerol and carbon dioxide in methanol using 1 mol% n Bu 2 SnO (dibutyltin(IV)oxide, 1 ) as a catalyst. The reaction attained equilibrium in 4 h and the yield of 1,2-glycerol carbonate obtained was as high as 35%. We observed the rate of the reaction depends on the amount of the catalyst and methanol used. During the reaction we could trap the intermediates and identify it by 13 C NMR, IR and mass spectrum of the reaction mixture. The reaction proceeds upon activation of 1 by methanol forming dibutyltindimethoxide followed by dibutyltinglycerate, which undergoes CO 2 insertion to produce non-isolable 7-membered tin–glycerolcarbonato complex that finally yield glycerol carbonate. Catalyst 1 was found to be successful even with 1,2-propanediol and ethylene glycol yielding the corresponding cyclic carbonate.
171 citations
TL;DR: In this paper, the onset date of the Indian summer monsoon (ISM) over the southern tip of India peninsula [also known as monsoon onset over Kerala (MOK)] has been determined by the beginning of the sustained 850-hPa zonal wind averaged over the Southern Arabian Sea (SAS) from 5° to 15°N, and from 40° to 80°E.
Abstract: The onset of the Indian summer monsoon (ISM) over the southern tip of the Indian peninsula [also known as monsoon onset over Kerala (MOK)] has been considered the beginning of India’s rainy season. The Indian Meteorological Department (IMD) makes an official prediction of ISM onset every year using a subjective method. Based on an analysis of the past 60-yr (1948–2007) record, the authors show that the onset date can be objectively determined by the beginning of the sustained 850-hPa zonal wind averaged over the southern Arabian Sea (SAS) from 5° to 15°N, and from 40° to 80°E. The rapid establishment of a steady SAS westerly is in excellent agreement with the abrupt commencement of the rainy season over the southern tip of the Indian peninsula. In 90% of the years analyzed, this simple and objective index has excellent agreement with the onset dates that are subjectively defined by the IMD. There are only 3 yr of the past 60 yr during which the two onset dates differ by more than 10 days, and non...
157 citations
TL;DR: In this article, the authors synthesize spherically shaped nanoparticles of cobalt ferrite having a size lying in the range of 13-14nm and the as prepared sample was sintered at 800-°C and the structural, magnetic and dielectric properties were measured.
125 citations
TL;DR: In this article, a low-temperature sintered dielectric material derived from Li2MgSiO4 (LMS) for low temperature co-fired ceramic (LTCC) application is discussed.
Abstract: Development of a low-temperature sintered dielectric material derived from Li2MgSiO4 (LMS) for low-temperature cofired ceramic (LTCC) application is discussed in this paper. The LMS ceramics were prepared by the solid-state ceramic route. The calcination and sintering temperatures of LMS were optimized at 850°C/4 h and 1250°C/2 h, respectively, for the best density and dielectric properties. The crystal structure and microstructure of the ceramic were studied by the X-ray diffraction and scanning electron microscopic methods. The microwave dielectric properties of the ceramic were measured by the cavity perturbation method. The LMS sintered at 1250°C/2 h had ɛr=5.1 and tan δ=5.2 × 10−4 at 8 GHz. The sintering temperature of LMS is lowered from 1250°C/2 h to 850°C/2 h by the addition of both lithium borosilicate (LBS) and lithium magnesium zinc borosilicate (LMZBS) glasses. LMS mixed with 1 wt% LBS sintered at 925°C/2 h had ɛr=5.5 and tan δ=7 × 10−5 at 8 GHz. Two weight percent LMZBS mixed with LMS sintered at 875°C/2 h had ɛr=5.9 and tan δ=6.7 × 10−5 at 8 GHz.
106 citations
TL;DR: In this article, a printed semi-elliptic monopole slot antenna for use in ultrawideband (UWB) communication systems is presented, which features a coplanar waveguide signal strip terminated with a semi-ELLiptic stub and a modified ground plane to achieve wide bandwidth from 2.85-20 GHz.
Abstract: A printed semi-elliptic monopole slot antenna for use in ultrawideband (UWB) communication systems is presented. The antenna features a coplanar waveguide signal strip terminated with a semi-elliptic stub and a modified ground plane to achieve wide bandwidth from 2.85-20 GHz. An exhaustive study of the radiation characteristics of this antenna in the frequency and time domains are presented. Design equations are derived and experimentally validated. Transient analysis indicates linear phase response and minimum dispersion to the transmitted pulse. The proposed radiator is omnidirectional with appreciable gain throughout the band.
106 citations
TL;DR: In this article, the magnetic properties such as magnetization and coercivity were measured using vibrating sample magnetometer, and the existence of a metastable cation distribution together with possible surface effects at the nanoregime.
96 citations
TL;DR: The present observation confirms the importance of dose and frequency of administration of immunostimulants in shrimp health management and gives maximum survival to shrimp feed containing 0.2% glucan when administered once every seven days.
95 citations
TL;DR: In this article, the authors proposed a compact wideband printed slot antenna, which is suitable for wireless local area network (WLAN) and satisfying the worldwide interoperability for microwave access (WiMAX) applications.
Abstract: A compact wideband printed slot antenna, suitable for wireless local area network (WLAN) and satisfying the worldwide interoperability for microwave access (WiMAX) applications, is proposed here. The antenna is microstrip-fed and its structure is based on Koch fractal geometry where the resonance frequency of a conventional triangular slot antenna is lowered by applying Koch iterations. The antenna size inclusive of the ground plane is compact and has a wide operating bandwidth. The proposed second iteration Koch slot antenna operates from 2.33 to 6.19 GHz covering the 2.4/5.2/5.8 GHz WLAN bands and 2.5/3.5/5.5 GHz WiMAX bands. The antenna exhibits omnidirectional radiation coverage with a gain better than 2.0 dBi in the entire operating band. Design equations for the proposed antenna are developed and their validity is confirmed on different substrates and for different slot sizes.
91 citations
TL;DR: A significant correlation between GSTP1 (105)Ile/(105) Ile genotype and the development of grade > or = 2 DIPN is found, which strongly suggests a role of oxidative stress in the pathophysiology of DIPn.
TL;DR: In this paper, the dielectric and thermo-mechanical properties of Sm2Si2O7 filled polyethylene and polystyrene composites for microwave packaging applications are reported.
Abstract: The dielectric and thermo-mechanical properties of Sm2Si2O7 filled polyethylene and polystyrene composites for microwave packaging applications are reported in this paper. The composites were synthesized by melt mixing and hot pressing methods. The effect of different volume fractions of the ceramic (vf = 0–0.5) on the dielectric properties of the composites was investigated at 1 MHz and at 8 GHz. The dielectric properties (relative permittivity and dielectric loss) were found to increase with the ceramic filler content. It was observed that the addition of 0.5 vf of Sm2Si2O7 filler to polyethylene, increased the relative permittivity and the dielectric loss to 5.3 and 0.009 respectively whereas the corresponding values for the polystyrene–Sm2Si2O7 composite are 4.6 and 0.01 respectively at 8 GHz. The variation of relative permittivity with temperature in the range −25 °C to 60 °C was investigated for both the composites. The relative permittivities obtained experimentally were compared with that of the theoretical predictions and Effective Medium Theory was found to agree well for both the composites. The thermal conductivity, thermal expansion coefficient and Vickers microhardness of the composites were also investigated.
TL;DR: In this article, the authors address two issues pertaining to legal pluralism in capture fisheries, particularly with regard to the South, and conclude that co-management is a process that brings legal systems and their constituent organizations and groups together within a single framework.
Abstract: This paper addresses two issues pertaining to legal pluralism in capture fisheries, particularly with regard to the South. First there is the problem of analysis. If legal pluralism is a common phenomenon, how is it to be discerned and understood? Secondly, there is the matter of institutional design: given the pervasiveness of legal pluralism, which management institutions are better suited to represent and resolve inter-legal system differences? The authors argue the case of co-management. Drawing on examples and insights from a comparative research project in South Asia, four basic types of legal pluralism and co-management are distinguished. The authors conclude that co-management is a process that brings legal systems, and their constituent organizations and groups, together within a single framework. For fisher organizations, which frequently have distinct legal perspectives, co-management is an essential path to legitimacy. For the state, other legal systems are a resource that management can draw upon.
TL;DR: In this paper, the frequency dependence of ac conductivity is analyzed by the power law σ(ω)ac = Bωn which is typical for charge transport by hopping or tunnelling processes.
Abstract: Mn1−xZnxFe2O4 nanoparticles (x = 0 to 1) were synthesized by the wet chemical co-precipitation technique. X-ray diffraction and transmission electron microscopy and high resolution transmission electron microscopy were effectively utilized to investigate the different structural parameters. The ac conductivity of nanosized Mn1−xZnxFe2O4 were investigated as a function of frequency, temperature and composition. The frequency dependence of ac conductivity is analysed by the power law σ(ω)ac = Bωn which is typical for charge transport by hopping or tunnelling processes. The temperature dependence of frequency exponent n was investigated to understand the conduction mechanism in different compositions. The conduction mechanisms are mainly based on polaron hopping conduction.
TL;DR: In this article, modified function projective synchronization between hyperchaotic Lorenz system and Lu system using adaptive method using Lyapunov stability theory has been investigated, and the adaptive control law and the parameter update law are derived to make the state of two hyper-chaotic systems modified functionprojective synchronized.
TL;DR: In this paper, Ni-filled multiwall carbon nanotubes (MWCNTs) were synthesized by template-assisted electrochemical deposition of Ni in MWCNTs.
Abstract: Nickel (Ni)-filled multiwall carbon nanotubes (MWCNTs) were synthesized by template-assisted electrochemical deposition of Ni in MWCNTs. Complex dielectric permittivity and magnetic permeability measurements of Ni nanowires (Ni NWs), MWCNTs, and Ni-filled MWCNTs were carried out in the S band. Ni-filled MWCNTs exhibited enhanced real (e 1 ) and imaginary (e 2 ) permittivity when compared to both Ni NWs and MWCNTs. This increase in e 1 and e 2 is attributed to the enhanced interfacial polarization, reduced eddy currents, and the presence of defects in MWCNTs. Ni-filled MWCNTs serve as an efficient microwave absorber in the S-band frequency regime.
TL;DR: In this article, two new complexes, [MII(L)(Cl)(H 2O)2]·H2O (where M = Ni or Ru and L = H2O base, 3-hydroxyquinoxaline-2-carboxalidene-4-aminoantipyrine), have been synthesized and characterized by elemental analysis, FT-IR, UV-vis diffuse reflectance spectroscopy, FAB-MASS, TG-DTA, AAS, conductance and magnetic susceptibility measurements.
Abstract: Two new complexes, [MII(L)(Cl)(H2O)2]·H2O (where M = Ni or Ru and L = heterocyclic Schiff base, 3-hydroxyquinoxaline-2-carboxalidene-4-aminoantipyrine), have been synthesized and characterized by elemental analysis, FT-IR, UV–vis diffuse reflectance spectroscopy, FAB-MASS, TG–DTA, AAS, cyclic voltammetry, conductance and magnetic susceptibility measurements. The complexes have a distorted octahedral structure and were found to be effective catalysts for the hydrogenation of benzene. The influence of several reaction parameters such as reaction time, temperature, hydrogen pressure, concentration of the catalyst and concentration of benzene was tested. A turnover frequency of 5372 h−1 has been found in the case of ruthenium complex for the reduction of benzene at 80 °C with 3.64 × 10−6 mol catalyst, 0.34 mol benzene and at a hydrogen pressure of 50 bar. In the case of the nickel complex, a turnover frequency of 1718 h−1 has been found for the same reaction with 3.95 × 10−6 mol catalyst under similar experimental conditions. The nickel complex shows more selectivity for the formation of cyclohexene while the ruthenium complex is more selective for the formation of cyclohexane.
TL;DR: The studies suggest that curcumin plays a vital role in regulating the activity of cholinergic and insulin receptors and mechanism of glucose transportation through Glut3, which results in normalizing the diabetes-mediated cerebellar disorders.
TL;DR: This paper studies the hybrid synchronization between two identical hyperchaotic Lu systems through synchronization of two pairs of states and anti-synchronization of the other two pair of states.
Abstract: In this paper, we study the hybrid synchronization between two identical hyperchaotic Lu systems. Hybrid synchronization of hyperchaotic Lu system is achieved through synchronization of two pairs of states and anti-synchronization of the other two pairs of states. Active controls are designed to achieve hybrid synchronization between drive and response systems using the sum and difference of relevant variables of the chaotic systems. Numerical simulations are presented to evaluate the analysis and effectiveness of the controllers.
TL;DR: In this paper, the authors synthesize composite materials based on natural rubber and nano-sized nickel by incorporating nickel nanoparticles in a natural rubber matrix for various loadings of the filler.
Abstract: Nanocomposites based on natural rubber and nano-sized nickel were synthesized by incorporating nickel nanoparticles in a natural rubber matrix for various loadings of the filler. Structural, morphological, magnetic and mechanical properties of the composites were evaluated along with a detailed study of dielectric properties. It was found that nickel particles were uniformly distributed in the matrix without agglomeration resulting in a magnetic nanocomposite. The elastic properties showed an improvement with increase in filler content but breaking stress and breaking strain were found to decrease. Dielectric permittivity was found to decrease with increase in frequency, and found to increase with increase in nickel loading. The decrease in permittivity with temperature is attributed to the high volume expansivity of rubber at elevated temperatures. Dielectric loss of blank rubber as well as the composites was found to increase with temperature.
TL;DR: In this article, an asymmetric coplanar strip (ACS) fed dual band F-shaped antenna covering the 2.4/5.2 GHz WLAN bands is presented.
Abstract: An asymmetric coplanar strip (ACS) fed dual band F-shaped antenna covering the 2.4/5.2 GHz WLAN bands is presented. The optimized dimensions of the proposed uniplanar antenna are 21 mm × 19 mm when printed on a substrate of dielectric constant 4.4 and height 1.6 mm. The dual band nature of the antenna is brought about by the various current paths in the F-shaped structure and the ground plane. The antenna exhibits nearly omnidirectional radiation characteristics and moderate gain in both the operating bands. Details of the antenna design, simulation, and experimental results are presented and discussed. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1852–1856, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24486
TL;DR: In this article, the reliability measures such as geometric vitality function and conditional Shannon's measures of uncertainty proposed by Ebrahimi (1996) and Sankaran and Gupta (1999), respectively, for the doubly (interval) truncated random variables.
Abstract: In this article, we study reliability measures such as geometric vitality function and conditional Shannon's measures of uncertainty proposed by Ebrahimi (1996) and Sankaran and Gupta (1999), respectively, for the doubly (interval) truncated random variables. In survival analysis and reliability engineering, these measures play a significant role in studying the various characteristics of a system/component when it fails between two time points. The interrelationships among these uncertainty measures for various distributions are derived and proved characterization theorems arising out of them.
TL;DR: In this article, a single-walled carbon nanotubes (SWNTs) were dispersed in water through ultrasonication and stabilized by the subsequent addition of a surfactant, and the stabilized aqueous dispersion of SWNTs was mixed with NR latex and the effect of nanofiller on the flow properties of NR latex was investigated.
Abstract: Natural rubber (NR)-based nanocomposites have been prepared with single-walled carbon nanotubes (SWNTs) through a latex stage mixing method. SWNTs were dispersed in water through ultrasonication and stabilized by the subsequent addition of a surfactant. The stabilized aqueous dispersion of SWNTs was mixed with NR latex and the effect of nanofiller on the flow properties of NR latex was investigated. Casting the compounded latex followed by curing gave good quality composite films with significantly improved mechanical properties. For example, the tensile strength and modulus of the composite film containing 2.0 phr (parts per hundred parts of rubber) SWNTs were, respectively, 56% and 63% higher in relation to pure NR. Electrical percolation threshold concentration of SWNTs in the NR matrix was found to be 1.5 phr. Thermogravimetric analysis indicated that the thermal stability of NR remains unaffected by the presence of SWNTs at low concentrations.
TL;DR: In this paper, the effects of aluminium doping concentration and annealing on particle size, lattice parameter and band gap energies were investigated for nanocrystalline fluorite-like structures of Ce 1− x Al x O 2− δ compounds.
TL;DR: The results suggest the glucose lowering effect of Costus pictus to be associated with the potentiation of insulin release from pancreatic islets and enhancement of peripheral utilization of glucose.
TL;DR: In this article, the authors used activated reactive evaporation (ARE) to obtain polycrystalline indium oxide thin films with a nominal thickness of 350 nm and a relatively high carrier concentration of 6.3 × 1020 cm-3, mobility 16 cm2 V-1s-1, with a low resistivity 1.01×10-3W cm.
Abstract: Tin doped indium oxide thin films were prepared on glass substrates kept at room temperature, by activated reactive evaporation (ARE). Structural, electrical and optical properties were studied for films having different thickness. The resulting films are polycrystalline and show ˜ 90 % transmission in the visible region. Hall effect measurements at room temperature for a film with a nominal thickness of ˜ 350 nm shows a relatively high carrier concentration ˜ 6.3 × 1020 cm-3, mobility ˜ 16 cm2 V-1s-1, with a low resistivity ˜ 1.01×10-3W cm.
TL;DR: In this article, the effect of additive addition and chemical modification on the pour point of coconut oil was analyzed using differential scanning calorimetry (DSC) and the results showed that the chemical modification procedures described in this work have been effective in improving the pour-point of the coconut oil to some extent.
Abstract: One of the major disadvantages of vegetable oils as base stock for lubricants is their high pour points. In this paper the crystallisation behaviour of coconut oil and the effect of additive addition and the chemical modification on its pour point were analysed using differential scanning calorimetry (DSC). Coconut oil showed the highest pour point among the vegetable oils considered in the study. This can be attributed to the predominantly saturated nature of its fatty acid constituents. Addition of additives did not show any significant improvement in the pour point of coconut oil. The chemical modification procedures described in this work have been effective in improving the pour point of coconut oil to some extent. The DSC method used in the present work has been found to be helpful in understanding the crystallisation behaviour of vegetable oils with different fatty acid compositions, the effect of additive addition and the chemical modification on pour point of coconut oil. Copyright © 2008 John Wiley & Sons, Ltd.
TL;DR: In this article, FeNi-based amorphous thin films were irradiated by 108 MeV Ag8+ ions at room temperature with fluences ranging from 1×1012 to 3×1013 ions/cm2 using a 15 UD Pelletron accelerator.
Abstract: Fe–Ni based amorphous thin films were prepared by thermal evaporation. These films were irradiated by 108 MeV Ag8+ ions at room temperature with fluences ranging from 1×1012 to 3×1013 ions/cm2 using a 15 UD Pelletron accelerator. Glancing angle x-ray diffraction studies showed that the irradiated films retain their amorphous nature. The topographical evolution of the films under swift heavy ion (SHI) bombardment was probed using atomic force microscope and it was noticed that surface roughening was taking place with ion beam irradiation. Magnetic measurements using a vibrating sample magnetometer showed that the coercivity of the films increases with an increase in the ion fluence. The observed coercivity changes are correlated with topographical evolution of the films under SHI irradiation. The ability to modify the magnetic properties via SHI irradiation could be utilized for applications in thin film magnetism.
TL;DR: In this article, the adaptive control law and the parameter update law were derived to make the state of two chaotic systems function projective synchronized by Lyapunove stability theory, and numerical simulations were presented to demonstrate the effectiveness of the proposed adaptive controllers.
TL;DR: This work presents a novel test case generation method that is based on dynamic slicing of UML activity diagrams using flow dependence graph (FDG) of an activity diagram to generate dynamic slices.
Abstract: UML diagrams are important design and modeling artifacts. These diagrams can also be used to generate test cases. We present a novel test case generation method that is based on dynamic slicing of UML activity diagrams. We use flow dependence graph (FDG) of an activity diagram to generate dynamic slices. Dynamic slices are created using an edge marking method. Slices are constructed corresponding to each conditional predicate on activity edges and test cases are automatically generated with respect to each slice. Our generated test cases satisfy path coverage criterion. Our test data generation scheme is automatic and the test data is generated considering the slice condition. We have implemented our approach to realize a prototype tool.