Showing papers by "Thapar University published in 2004"
TL;DR: In this paper, the results of an experimental investigation dealing with concrete incorporating high volumes of Class F fly ash Portland cement was replaced with three percentages (40, 45, and 50%) of Class-F fly ash Tests were performed for fresh concrete properties: slump, air content, unit weight, and temperature Compressive, splitting tensile, and flexural strengths, modulus of elasticity, and abrasion resistance were determined up to 365 days of testing.
478 citations
TL;DR: In this paper, a resistor model is presented for easy estimation of effective thermal conductivity (ETC) of highly porous metal foams based on experimental data available, which is based on numerical simulations in which ETC of a random two-phase medium is being comprised of contributions from both the phases.
183 citations
TL;DR: In this paper, the effects of applied voltage and temperature on liquid crystal droplet morphology and its transmission characteristics were studied, and it was shown that threshold voltage and optical transmission increases with increasing temperature.
106 citations
TL;DR: This paper shall analyse the RR interval time series from selected subjects for different sampling frequencies to compare the error introduced in selected frequency-domain measures of HRV at a constant frequency resolution for a specific duration of electrocardiogram (ECG) data.
Abstract: Spectral analysis of heart rate variability (HRV) is an accepted method for assessment of cardiac autonomic function and its relationship to numerous disorders and diseases. Various non-parametric methods for HRV estimation have been developed and extensive literature on their respective properties is available. The RR interval time series can be seen as a series of non-uniformly spaced samples. To analyse the power spectra of this series using the discrete Fourier transform (DFT), we need to interpolate the series for obtaining uniformly spaced intervals. The selection of sampling period plays a critical role in obtaining the power spectra in terms of computational efficiency and accuracy. In this paper, we shall analyse the RR interval time series from selected subjects for different sampling frequencies to compare the error introduced in selected frequency-domain measures of HRV at a constant frequency resolution for a specific duration of electrocardiogram (ECG) data. It should be pointed out that, although many other error causes are possible in the frequency-domain measures, our attention will be confined only to the performance comparison due to the different sampling frequencies. While the choice of RR interval sampling frequency (f(s)) is arbitrary, the sampling rate of RR interval series must be selected with due consideration to mean and minimum RR interval; f(s = )4 Hz was proposed for a majority of cases. This is an appropriate sampling rate for the study of autonomic regulation, since it enables us to compute reliable spectral estimates between dc and 1 Hz, which represents the frequency band within which the autonomic nervous system has significant response. Furthermore, resampled RR intervals are evenly spaced in time and are synchronized with the samples of the other physiologic signals, enabling cross-spectral estimates with these signals.
86 citations
TL;DR: Micropropagation protocol for an elite selection of Aloe vera syn A. barbadensis through enhanced axillary branching was standardized and the plants were successfully transferred in the soil and were morphologically similar to mother plants.
Abstract: Micropropagation protocol for an elite selection of Aloe vera syn A. barbadensis through enhanced axillary branching was standardized. Murashige and Skoog medium containing 1 mg l−1 BA and 0.2 mg l-1 IBA gave highest multiplication. Citric acid at 10mg l-1 and liquid medium improved the shoot multiplication. Hundred per cent microshoots produced rooted plantlets within 15 days of culture on hormone-free agar medium. Liquid medium during rooting stage decreased the number of shoots showing rooting response. The plants were successfully transferred in the soil and were morphologically similar to mother plants.
74 citations
TL;DR: A new ion-selective electrode based on dicyclohexano-18-crown-6 (DC18C6) as a neutral carrier is developed for lanthanum(III) ions and the selectivity coefficients for mono-, di-, and trivalent cations indicate good selectivity for La( III) ions over a large number of interfering cations.
60 citations
TL;DR: In this article, a new and efficient method using ultrasonic activation for intercalation by ion exchange and microwave heating for formation of zirconium polyoxycationic species in the preparation of ZrO2-pillared clay composite with improved physico-chemical properties and significant reduction in processing time.
Abstract: We herein report for the first time, a new and efficient method using ultrasonic activation for intercalation by ion exchange and microwave heating for formation of zirconium polyoxycationic species in the preparation of ZrO2-pillared clay composite with improved physico-chemical properties and significant reduction in processing time. Acetic anhydride under solventless conditions with microwave irradiation in the presence of ZrO2-pillared clay was used for the mono-acylation of diols and alcohols in very good yield.
45 citations
TL;DR: A comparative analysis for RR interval segment durations has been made and it was concluded that segment length of 256 samples with 50% overlapping provides a smoothed spectral estimate with clearly outlined peaks in low- and high-frequency bands.
Abstract: Although patterns of heart rate variability (HRV) hold considerable promise for clarifying issues in clinical applications, the inappropriate quantification and interpretation of these patterns may obscure critical issues or relationships and may impede rather than foster the development of clinical applications. The duration of the RR interval series is not a matter of convenience but a fine balance between two important issues: acceptable variance and stationarity of the time series on one hand, and acceptable resolution of the spectral estimate and reduced spectral leakage on the other. Further, in the standard short-term HRV analysis, it has been observed that the previous studies in HRV spectral analysis use a wide range of RR interval segment duration for spectral estimation by Welch's algorithm. The standardization of RR interval segment duration is also important for comparisons among studies and is essential for within-study experimental contrasts. In the present study, a comparative analysis for RR interval segment durations has been made to propose an optimal RR interval segment duration. Firstly a simulated signal was analyzed with Hann window and zero padding for the segment lengths of 1024, 512, 256 and 128 samples resampled at 4 Hz with 50% overlapping. Again, the above procedure was applied to RR interval series and it was concluded that segment length of 256 samples with 50% overlapping provides a smoothed spectral estimate with clearly outlined peaks in low- and high-frequency bands. This easily understandable and interpretable spectral estimate leads to a better visual and automated analysis, which is not only desirable in basic physiology studies, but also a prerequisite for a widespread utilization of frequency domain techniques in clinical studies, where simplicity and effectiveness of information are of primary importance.
42 citations
TL;DR: In this paper, damping resistors across series capacitors are proposed to damp out the starting transients and for the stable operation of short-shunt self-excited induction generator feeding induction motor loads.
Abstract: The configuration of short-shunt self-excited induction generator feeding induction motor loads (SEIG-IM) suffers from excessive transients during startup of motor load under no load and unstable operation. These problems may be due to subsynchronous resonance as obtained with series compensated transmission line or due to the connected load system. The use of damping resistors across series capacitors is proposed to damp out the starting transients and for the stable operation. The steady-state model of short shunt SEIG-IM with damping resistors and resistive and motor load is developed to obtain the values of shunt and series capacitances for optimum voltage regulation. The simulated annealing like approach is used to solve voltage regulation optimization problem. The values of shunt and series capacitances and damping resistance are obtained for optimum voltage regulation under entire loading range and stable operation during starting and loading. The results are experimentally verified, which establish the effectiveness of damping resistance and developed algorithm.
42 citations
TL;DR: In this article, the creep behavior of a rotating disc made of isotropic functionally graded material (FGM) has been investigated and it is shown that the steady-state strain rates are significantly lower compared to that in an isotropically disc with uniform particle distribution.
Abstract: Creep behavior of a rotating disc made of isotropic functionally graded material (FGM) has been investigated. The disc under investigation is made of a composite containing silicon carbide particles in a matrix of pure aluminum. The creep behavior has been described by Sherby’s law. The disc is considered as having a thermal gradient in the radial direction. The present analysis indicates that for the assumed linear particle distribution, the steady-state strain rates are significantly lower compared to that in an isotropic disc with uniform particle distribution. It is also found that the strain rates in composite discs operating under thermal gradient are reduced as compared to similar discs under a uniform average temperature.
41 citations
TL;DR: In this article, an investigation carried out to examine the factors influencing collapse settlement of the compacted coal ash due to wetting was carried out and the collapse potential was correlated with the mean size of the ash.
Abstract: The paper describes an investigation carried out to examine the factors influencing collapse settlement of the compacted coal ash due to wetting. The ashes produced by the coal fired thermal power plants are stored as a high mound in the disposal dump. Some of the ash dumps and ash fill structures wetted under certain conditions of loading may exhibit collapse. Attempts have been made to correlate the ash characteristics and the specific placement parameters such as ash type, soluble content, degree of compaction, overconsolidation ratio, moisture content, and stress level at wetting with collapse. This was based largely on the oedometer and partly on the model and the field test results. 378 single oedometer tests were conducted to obtain the collapse potential. The collapse potential was correlated with the mean size of the ash. The favorable pressure, moisture, fines, compaction, soluble substance, and prestressing decrease the collapse potential of an ash fill. The collapsible and the noncollapsible ashes were identified by the results of oedometer test and laboratory model test. Normally, if the collapse potential in the oedometer is more than 0.01, the collapse of soils may occur in the field. However, the model test demonstrated this to be an unconservative criterion. A value of 0.0075 at 80% degree of compaction was found appropriate for the ashes examined. The paper explains the technique of field test performed at the controlled densities. The field test confirmed incidence of collapse on a rising water table for a collapsible ash.
TL;DR: In this article, a number of Sm (III) selective membranes of varying compositions using tin (IV) boratophosphate as electroactive material were prepared, and polyvinyl chloride, polystyrene and epoxy resin were used as binding materials.
Abstract: : A number of Sm (III) selective membranes of varying compositions using tin (IV) boratophosphate as electroactive material were prepared. Polyvinyl chloride, polystyrene and epoxy resin were used as binding materials. Membrane having composition of 40% exchanger and 60% epoxy resin exhibited best performance. This membrane worked well over a wide concentration range of 1x10 -5 M to 1x10 -1 M of samarium ions with a Super-Nernstian slope of 40 mV/decade. It has a fast response time of less than 10 seconds and can be used for at least six months without any considerable divergence in potentials. The proposed sensor revealed good selectivities with respect to alkali, alkaline earth, some transition and rare earth metal ions and can be used in the pH range of 4.0-10.0. It was used as an indicator electrode in the potentiometric titration of Sm (III) ions against EDTA. Effect of internal solution was studied and the electrode was successfully used in non-aqueous media, too. Keywords:
TL;DR: In this paper, a new PVC-based membrane using dibenzo-18-crown-6 (DB18C6) as an ionophore has been developed as a calcium ion selective electrode.
Abstract: A new PVC based membrane using dibenzo-18-crown-6 (DB18C6) as an ionophore has been developed as a calcium ion selective electrode. The electrode comprises of ionophore (7%), PVC (85%) and plasticizer (8%). The electrode shows a linear dynamic response in the concentration range of 1×10−5 M to 1×10−1 M with a Nernstian slope of 28.0 mV/decade and a detection limit as 4×10−6 M. It has a response time of
05 Jul 2004
TL;DR: In this article, the degradation of cellulose paper used as insulating material in transformer degrades under thermal and electrical stresses, and different structural features of these aged papers are described.
Abstract: Cellulose paper used as insulating material in transformer degrades under thermal and electrical stresses. In order to understand the cause of degradation, paper was exposed to varied thermal and electrical stresses in an indigenously designed and fabricated test cell for different duration. The present paper describes different structural features of these aged papers.
TL;DR: In this article, the stability margin of a constant flow valve compensated hole-entry hybrid journal bearing system considering bearing flexibility and variation of viscosity due to temperature rise of the lubricant was investigated.
Abstract: This paper deals with the stability margin of a constant flow valve compensated hole-entry hybrid journal bearing system considering bearing flexibility and variation of viscosity due to temperature rise of the lubricant. The journal temperature is computed on the basis of average fluid-film temperature and axisymmetric isothermal element is assumed. The coupled solution of Reynolds, energy, conduction, and elasticity equations is obtained using finite element method. The performance of a symmetric and asymmetric hole-entry hybrid journal bearing configurations is studied. The results presented in the study indicate that the bearing flexibility and temperature rise of the lubricant fluid-film affects the performance of the hole-entry hybrid journal bearing system quite significantly and proper selection of restrictor design parameter is quite useful in maintaining the fluid film thickness and threshold speed of the journal.
TL;DR: In this article, the polymer viscosity affects the droplet size, morphological uniformity, electro-optic properties, and also the extent to which the phase separation is complete.
Abstract: Poly(dimethyl)siloxanes of different viscosity have been synthesized by hydrolytic condensation of dimethyldichloro silane. Polysiloxane dispersed ferroelectric liquid crystal (PDFLC) composite films were prepared simultaneously by solvent induced and polymer induced phase separation techniques (SIPS and PIPS, respectively). These composite films were prepared by mixing polymer and ferroelectric liquid crystal mixture in diethyl ether and then adding 0.2% of room temperature vulcanizer for crosslinking. Film morphology, droplet size, and electro-optic parameters of PDFLC systems have been studied by using polysiloxanes of different viscosity. We show that the polymer viscosity affects the droplet size, morphological uniformity, electro-optic properties, and also the extent to which the phase separation is complete. These composite systems show the switching time of few microseconds. Structure-property correlation in these materials have been studied and explained on the basis of polysiloxane viscosity. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 159–166, 2004
TL;DR: In this paper, the dielectric spectroscopy of a short pitch and high spontaneous polarization ferroelectric liquid crystal mixture and its guest-host derivatives with different wt/wt ratio of anthraquinone blue dichroic dye has been studied over a wide frequency range of 50-1 MHz.
01 Jan 2004
TL;DR: This chapter includes some advanced techniques such as the revised simplex method, bounded variable technique and decomposition principle, which are modified extensions of the simplex algorithm to solve different types of linear programming problems.
Abstract: This chapter includes some advanced techniques such as the revised simplex method, bounded variable technique and decomposition principle. These all are the modified extensions of the simplex algorithm to solve different types of linear programming problems. In the end, the interior point algorithm due to Karmarkar is introduced.
TL;DR: The sequence comparison of KN6 of Indian isolate showed high sequence similarities with the isolates of Pisolithus associated with Eucalyptus from Australia, which suggested that Pisolithic isolates found in India are P. albus.
TL;DR: In this article, the effect of applied voltage and temperature on switching time has been investigated in homogeneously aligned 5 µm thin cell filled with (FLC-6980) ferroelectric liquid crystal mixture using field reversal method and Sawyer tower method.
Abstract: Switching dynamics have been investigated in homogeneously aligned 5 µm thin cell filled with (FLC-6980) ferroelectric liquid crystal mixture using field reversal method and Sawyer Tower method. The effect of applied voltage and temperature on switching time has been studied. It has been observed that switching time decreases with the increase of applied voltage and also with the rise of temperature. The tortional viscosity has been calculated. It shows Arrhenius type behavior. Hysteresis loop has been studied at different temperatures and at different frequencies. It has been observed that coercive field (Ec) increases with the increase of frequency. Ec has non-zero value at zero frequency, which is important characteristics of ferroelectrics. Ec increases near the transition temperature.
TL;DR: ZrO2-pillared clay (Zr-PILC) was used for the selective, monotetrahydropyranylation under solvent-free condition both by heating and microwave irradiation of 1,n-symmetrical diols and simple alcohols with good selectivity and conversion in high yields as discussed by the authors.
TL;DR: In this paper, two homologous series possessing a central biphenyl methane core have been synthesized, the central core having two lateral fluoro substituents, and both the series have six-ring structures and exhibit smectic mesophases of high thermal stability.
Abstract: Ferroelectric properties in liquid crystals are no longer restricted to materials with a chiral molecular structure; ferroelectricity has been observed in a smectic phase formed by bent achiral molecules. Accordingly, two homologous series possessing a central biphenyl methane core have been synthesized, the central core having two lateral fluoro substituents. Both the series have six-ring structures and exhibit smectic mesophases of high thermal stability. The flexible biphenyl methane core imparts a slight curve to the molecules, giving them a bent shape.
TL;DR: In this paper, the authors measured the concentration of suspended particulate matter, organic tarry matter (BSPM), ignitable matter (LOI), and lead in the ambient air of an urban area using a high volume sampler.
Abstract: Concentration levels of suspended particulate matter (SPM), organic tarry matter (BSPM), ignitable matter (LOI) and lead in the ambient air of an urban area are measured by using a high volume sampler. SPM levels in different zones of the city are reported. Organic tarry matter measured as benzene soluble particulate matter (BSPM) constitutes about 4–9% of the SPM. BSPM in the ambient air varies in a range of 10–40 μg m−3. Ignitable matter measured as loss on ignition (LOI) forms about 24–40% of the SPM. Absolute values of LOI vary between 50 and 150 μg m−3. Concentrations of BSPM, LOI and Pb are correlated to automobile exhaust as the probable source. The studies indicate that BSPM and LOI are integral parts of the SPM but their concentrations are independent of the SPM levels.
05 Jan 2004
TL;DR: A carry chain design optimized for implementing multipliers along with the adder circuitry is presented, which will be very useful for designs which have very large number of mathematical operations in it.
Abstract: This paper presents a carry chain design optimized for implementing multipliers along with the adder circuitry. This kind of architecture will be very useful for designs which have very large number of mathematical operations in it. The aim of the architecture is to accommodate as much logic as possible in one LUT without increasing the size of the LUT proportionately. The discussed carry chain design is compatible with both 3-input as well as 4-input LUTs. The paper ends with a comparative study of multiplier implementation on various popular FPGA architectures.
01 Mar 2004
TL;DR: In this paper, a criterion for the L 1 -convergence of modified sine sums under a new class K is introduced and a necessary and sucient criterion is obtained.
Abstract: New modified sine sums are introduced and a criterion for the L 1 -convergence of these modified sine sums under a new class K is obtained Also a necessary and sucient
TL;DR: Transition metal ions like Cr3+, Co2+, Ni2+ and Cu2+ show an increase in relative percentage inhibition with increasing atomic number, and are found to be highly toxic to microbes.
Abstract: The toxic effect of metal ions like chromium (Cr3+), cobalt (Co2+), nickel (Ni2+), copper (Cu2+), cadmium (Cd2+) and lead (Pb2+) on biochemical oxygen demand (BOD) of synthetic wastewater samples has been studied at different temperatures i.e., 15 degrees C, 20 degrees C, 25 degrees C and 30 degrees C. Experiments were conducted for BOD exertion in presence (10 ppm of each metal ion) and in the absence of metal ions at different temperatures. Transition metal ions like Cr3+, Co2+, Ni2+ and Cu2+ show an increase in relative percentage inhibition with increasing atomic number. BOD inhibition in presence of Cd2+ and Pb2+ is relatively large. The metal ions under study are found to be highly toxic to microbes.
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TL;DR: In this article, it was proved that the complex double Fourier series of an integrable function with coefficients satisfying certain conditions converges in the L 1 norm in the case of Hardy-Karamata condition.
Abstract: It is proved that the complex double Fourier series of an integrable function $f(x,y)$ with coefficients $\{c_{jk}\}$ satisfying certain conditions, will converge in $L^{1}$-norm. The conditions used here are the combinations of Tauberian condition of Hardy--Karamata kind and its limiting case. This paper extends the result of Bray [1] to complex double Fourier series.
11 Dec 2004
TL;DR: A fractional Fourier transform (FrFT) based optimal beamforming in micro-cellular environments over AWGN channel is considered for reducing MSE at no extra computational cost.
Abstract: The next generation mobile services like variable bandwidth; desktop/multimedia with mobility and service personalization shall be enabled by putting new technologies and systems in use. In order to provide these services in wireless fashion the requirements on data rate, link quality, spectral efficiency, and mobility cannot be met with conventional beamforming. Therefore new beamforming techniques are essential to increase the spectral efficiency of wireless communication systems. In this paper a fractional Fourier transform (FrFT) based optimal beamforming in micro-cellular environments over AWGN channel is considered for reducing MSE at no extra computational cost. The results are achieved by use of FrFT based beamforming for a moving and accelerating source in a micro-cellular environment.
TL;DR: In this paper, structural and thermal properties of PCT ceramics are studied by the substitution of Ta in the titanium site, and all the samples show tetragonal structure.
Abstract: Structural and thermal properties of PCT ceramics are studied by the substitution of Ta in the titanium site. Samples with compositional formula Pb0.76Ca0.24Mn0.02Ti0.98−5x/4TaxO3 with the variation in x from 0 to 0.04 in steps of 0.01, were prepared by the conventional dry ceramic method. Single-phase formation was confirmed from the X-ray analysis and all the samples show tetragonal structure. Lattice parameters ‘c’ and ‘a’ were found to decrease and increase with substitutional parameter x, respectively. Tetragonality (c/a) decreases with increasing Ta content. Dilatometric study was done to analyze the shrinkage behaviour of green and sintered samples.
01 Jan 2004
TL;DR: This chapter develops the theory of simplex method to solve linear programming problems and explains some difficulties which are encountered when simplex iterations are executed.
Abstract: This chapter develops the theory of simplex method to solve linear programming problems. The other methods are slight variants of the simplex method known as big-M method and two phase method. In the end, we explain some difficulties which are encountered when simplex iterations are executed.