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101.
Cd1 ? x Pb x S thin films were prepared by spray pyrolysis technique onto glass substrate at 300°C temperatures. The prepared films were characterized elemental, structural and optical properties by energy dispersive X-ray, scanning electron microscopy, X-ray diffraction and UV-VIS spectrophotometer. Energy dispersive X-ray confirmed the presence of Cd, S and Pb in the films. SEM images show that the deposition covered the substrate well uniformly and incorporation of Pb. Crystal structure was found hexagonal and the estimated grain size was lies in between 9 to 49 nm. The optical band gap was decreased from 2.43 to 2.07 eV. 相似文献
102.
J.D. Schwarzkopf C.T. Crowe J.J. Riley S. Wetchagarun P. Dutta 《International Journal of Multiphase Flow》2009
This study focuses on understanding how the presence of particles, in homogeneous turbulence decay, affects the dissipation of dissipation coefficient within the volume averaged dissipation transport equation. In developing this equation, the coefficient for dissipation of dissipation was assumed to be the sum of the single phase coefficient and an additional coefficient that is related to the effects of the dispersed phase. Direct numerical simulation was used to isolate the effect of stationary particles in homogeneous turbulent decay at low Reynolds numbers (ReL = 3.3 and 12.5). The particles were positioned at each grid point and modeled as point forces and a comparison was made between a 643 and 1283 domain. The results show that the dissipation of dissipation coefficient correlates well with a dimensionless parameter called the momentum coupling factor. 相似文献
103.
S. C. Dutta Roy 《Circuits, Systems, and Signal Processing》2010,29(4):629-636
A new Chebyshev-like low-pass filter approximation is proposed for which the order is always odd and hence there is no problem
for doubly terminated LC ladder realization. Flexibility of shaping the response and lower Q values of complex poles appear to be the major advantages of the new approximation as compared to the normal Chebyshev filter. 相似文献
104.
Polycrystalline samples of Fe-modified PLZT (lead lanthanum zirconate titanate) are prepared by a mixed-oxide reaction technique.
The formation of the compound has been confirmed by X-ray powder diffraction studies. The unit cell structure of the material
has been found to be rhombohedral. Fourier-transform infrared reflection (FTIR) spectra have been recorded to correspond the
structural changes associated with the phase formation. The effects of Fe concentration on the microstructure and dielectric
constant of PLZT materials have been investigated. The ferroelectric phase transition of PLFZT materials is studied using
dielectric measurements, which shows a shift in the transition temperature towards the higher-temperature side with increased
Fe ion concentration. The piezoelectric constants of this system are investigated by the same way of changed contents of Fe
ion in the main PLZT compound. The optimum values of Qm, kp, and d33 are 73, 0.32 and 406. The electrical conductivity increases with the increase in Fe ion concentration.
PACS 77.80.Bh; 77.84.Dy; 77.22.Ch; 72.15.Eb; 06.60.Ei; 39.30.+w 相似文献
105.
E. Gopinathan S. C. Dutta Roy R. K. Patney 《Circuits, Systems, and Signal Processing》1987,6(1):95-106
A single-parameter controlled-variable amplitude change function has been constructed for digital filtering using multiple units of a prototype filter. The limits of variation are discussed. The technique is shown to be useful not only for the reduction of errors in either the pass band or the stop band of the overall filter, but also for varying the cutoff frequency of the overall filter over a wide range. Hardware implementation problems resulting from a wide variation are shown to be overcome by a modular approach. 相似文献
106.
Measurements of the intensity of an injection locked 1.54 μm InGaAsP laser are reported. The change in intensity of the locked laser across the locking range is quite asymmetric, with a shape that agrees well with the theory of Lang. A linewidth parameter ofalpha = 6 pm 1 was determined from the magnitude of the locking range. The injection locked laser was found to be unstable on the high frequency end of the locking range. The physical origin of this instability is explained in terms of a laser intensity change altering the phase of the laser field relative to that of the injected field. 相似文献
107.
M. Dutta 《Applied Surface Science》2008,254(9):2743-2747
ZnO thin films are deposited on the glass substrates by sol-gel drain coating technique by varying the concentration of the sol. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis were used to investigate the effect of sol concentration on the crystallinity and surface morphology of the films. The results show that with increase in sol concentration, the value of full width at half maximum (FWHM) of (0 0 2) peak decreases while the strain first increases and then decreases. The sol with higher concentration results in the increase in the grain size. The studies on the optical properties show that the band gap value increases from 3.27 to 3.3 eV when the sol concentration changes from 0.03 to 0.1 M. The photoconductivity studies reveal that the film for 0.05 M sol shows the maximum photoresponse for ultraviolet (UV) wavelength (<400 nm) which is co-related with the deep-level defects. The growth and decay of the photocurrent is found to be slowest for the same film. 相似文献
108.
We introduce a single step memory dependence in the fully chaotic logistic map. This makes it a two dimensional system in general. However, we show that by using composite functions to define two one dimensional maps, it is possible to obtain some analytic results for the bifurcation structure. Numerical results support the calculated bifurcation scheme and, in addition, yield a further insight which allows the calculation of the convergence ratio for a new period adding scenario. 相似文献
109.
Decomposition of clay from Garo Hills of Meghalaya (India) was studied by dynamic thermogravimetry. A fourteen kinetic equation procedure was applied for analysis of non-isothermal weight change upto a temperature of 1223 K. Two stages of decomposition were clearly distinguised i.e. the initial dehydration period at temperature 373 K to 673 K and the dehydroxylation period in the temperature range 723 K to 1073 K. First order decomposition mechanism was found to be applicable to both dehydration and dehydroxylation steps. Activation energies of 67 kJ/mol and 278 kJ/mol are estimated for the first and second steps with frequency factors of 16.3 s–1 and 5.16×106s–1 respectively. The weight loss relating to the steps in TG curves allows determination of the contents of the basic mineral in the clay. Percentages of Al2O3.SiO2 and total volatiles as calculated from weight loss data are in accordance with the results of classical chemical analysis.
Zusammenfassung Mittels DTG wurde die thermische Zersetung von Ton aus der Garo-Hills-Gegend bei Meghalaya (Indien) untersucht. Zur Analyse der nicht-isothermen Gewichtsveränderungen bis zu einer Temperatur von 1223 K wurde ein Verfahren mit vierzehn kinetischen Gleichungen angewendet. Zwei Teilschritte der Zersetzung können eindeutig unterschieden werden, nämlich die anfängliche Dehydratationsperiode bei Temperaturen von 373 bis 673 K und die Dehydroxylierungsperiode bei Temperaturen zwischen 723 K un 1073 K. Für beide Vorgänge konnte als Reaktionsmechanismus eine Zersetzung erster Ordnung angewendet werden. Für den ersten un zweiten Teilschritt konnten Aktivierungsenergien von 67 kJ/mol bzw. 278 kJ/mol un Frequenzfaktoren von 16.3s–1 bzw. 5.16×106s–1 ermittelt werden. Der aus den TG-Kurven hervorgehende Gewichtsverlust läßt auf den Gehalt des Tones an Basismineral schließen. Der prozentuelle Gehalt an Al2O3, SiO2 und der gesamten flüchtigen Bestandteile, berechnet aus den Gewichtsverlusdaten, stimmt mit den Ergebnissen aus herkömmlichen chemischen Analysen überein.相似文献
110.
Soma Mani Galbraith Douglas C. White Robert L. 《IEEE transactions on bio-medical engineering》1987,(4):276-282
Radio-frequency (RF) coils are used extensively in the design of implantable devices for transdermal power and data transmission. The practical issues of coil misalignments and configurations have not been investigated, and this paper presents a detailed theoretical analysis of misalignment effects in RF coil systems, including lateral and angular misalignments. Formulas are derived for the mutual inductance and, whenever possible, simplified upper bounds and lower bounds of the coupling coefficient are provided. A design procedure is established to maximize coil coupling for a given configuration, and a companion paper [1] discusses a circuit design technique to reduce the effects of misalignment on transmission efficiency. 相似文献