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71.
R. M. Dey M. Pandey D. Bhattacharyya D. S. Patil S. K. Kulkarni 《Bulletin of Materials Science》2007,30(6):541-546
Diamond-like carbon (DLC) films were deposited by microwave assisted chemical vapour deposition system using d.c. bias voltage
ranging from −100 V to −300 V. These films were characterized by X-ray photoelectron spectroscopy (XPS) and spectroscopic
ellipsometry techniques for estimating sp
3/sp
2 ratio. The sp
3/sp
2 ratio obtained by XPS is found to have an opposite trend to that obtained by spectroscopic ellipsometry. These results are
explained using sub-plantation picture of DLC growth. Our results clearly indicate that the film is composed of two different
layers, having entirely different properties in terms of void percentage and sp
3/sp
2 ratio. The upper layer is relatively thinner as compared to the bottom layer. 相似文献
72.
Wang C.-C. Kulkarni S. R. Poor H. V. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2007,53(1):56-81
This paper focuses on finite-dimensional upper and lower bounds on decodable thresholds of Zopfm and binary low-density parity-check (LDPC) codes, assuming belief propagation decoding on memoryless channels. A concrete framework is presented, admitting systematic searches for new bounds. Two noise measures are considered: the Bhattacharyya noise parameter and the soft bit value for a maximum a posteriori probability (MAP) decoder on the uncoded channel. For Zopf m LDPC codes, an iterative m-dimensional bound is derived for m-ary-input/symmetric-output channels, which gives a sufficient stability condition for Zopfm LDPC codes and is complemented by a matched necessary stability condition introduced herein. Applications to coded modulation and to codes with nonequiprobably distributed codewords are also discussed. For binary codes, two new lower bounds are provided for symmetric channels, including a two-dimensional iterative bound and a one-dimensional noniterative bound, the latter of which is the best known bound that is tight for binary-symmetric channels (BSCs), and is a strict improvement over the existing bound derived by the channel degradation argument. By adopting the reverse channel perspective, upper and lower bounds on the decodable Bhattacharyya noise parameter are derived for nonsymmetric channels, which coincides with the existing bound for symmetric channels 相似文献
73.
Photocatalytic degradation of dyes and organic contaminants in water using nanocrystalline anatase and rutile TiO2 总被引:1,自引:0,他引:1
Rajesh J. Tayade Praveen K. Surolia Ramchandra G. Kulkarni Raksh V. Jasra 《Science and Technology of Advanced Materials》2007,8(6):455-462
Nanocrystalline TiO2 was synthesized by controlled hydrolysis of titanium tetraisopropoxide. The anatase phase was converted to rutile phase by thermal treatment at 1023 K for 11 h. The catalysts were characterized by X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), Fourier-transform infrared absorption spectrophotometry (FT-IR) and N2 adsorption (BET) at 77 K. This study compare the photocatalytic activity of the anatase and rutile phases of nanocrystalline TiO2 for the degradation of acetophenone, nitrobenzene, methylene blue and malachite green present in aqueous solutions. The initial rate of degradation was calculated to compare the photocatalytic activity of anatase and rutile nanocrystalline TiO2 for the degradation of different substances under ultraviolet light irradiation. The higher photocatalytic activity was obtained in anatase phase TiO2 for the degradation of all substances as compared with rutile phase. It is concluded that the higher photocatalytic activity in anatase TiO2 is due to parameters like band-gap, number of hydroxyl groups, surface area and porosity of the catalyst. 相似文献
74.
Experimental verification of a low temperature (<20 °C), reactive plasma etch process for copper films is presented. The plasma etch process, proposed previously from a thermochemical analysis of the Cu-Cl-H system, is executed in two steps. In the first step, copper films are exposed to a Cl2 plasma to preferentially form CuCl2, which is volatilized as Cu3Cl3 by exposure to a H2 plasma in the second step. Plasma etching of thin films (9 nm) and thicker films (400 nm) of copper has been performed; chemical composition of sample surfaces before and after etching has been determined by X-ray photoelectron and flame atomic absorption spectroscopies. 相似文献
75.
Ioannis Tomkos Anna Tzanakaki Prasad Kulkarni George Markidis Carmen Mas Machuca 《电信纪事》2007,62(5-6):567-583
In transparent optical networks, the optical signal accumulates the effects of all physical impairments present along the path it traverses. The conventional selection of signal paths based on e.g. shortest path routing without considering the signal quality and its association with the physical impairments does not always provide the optimum solution in terms of network performance such as blocking and resource utilization. This paper proposes an impairment constraint based routing algorithm to achieve an optimal combination of physical and networking performance taking into account all physical linear impairments including noise, chromatic and polarization mode dispersion, crosstalk and filter concatenation effects in an integrated approach. The performance of a typical metropolitan area network is examined and the improvement achieved when using the proposed approach compared to the conventional shortest path routing is demonstrated. 相似文献
76.
ZnS thin films of different thicknesses were prepared by chemical bath deposition using thiourea and zinc acetate as S2− and Zn2+ source. The effect of film thickness on the optical and structural properties was studied. The optical absorption studies
in the wavelength range 250–750 nm show that band gap energy of ZnS increases from 3·68–4·10 eV as thickness varied from 332–76
nm. The structural estimation shows variation in grain size from 6·9–17·8 nm with thickness. The thermoemf measurement indicates
that films prepared by this method are of n-type. 相似文献
77.
Pavan S. Kulkarni Sachin D. Ghude S. L. Jain B. C. Arya P. K. Dubey Shahnawaz 《International journal of remote sensing》2013,34(6):1545-1559
A tropospheric ozone variability study is carried out to investigate the spatial and temporal distribution over the coastline of the Indian peninsula and adjacent land and sea using NASA Langley Tropospheric Ozone Residual data set for the period 1979–2005. A strong seasonal cycle has been observed with large variation (~ 55%) over the upper eastern coast, followed by the upper and lower western coast, compared to the lower eastern coast (~ 33%). A negative gradient in ozone concentration is observed along eastern and western coasts during summer (slope ~ –0.78 and –0.65) and a positive gradient (slope ~ 0.16 and 0.21) during winter. The same is observed over the adjacent land and sea along the coastline with slight variation. This change in gradient can be attributed to the anthropogenic emission of precursor gases that reinforce localized photochemical production of ozone. In addition, topography, transport, seasonality of emission of precursor gases and the solar insolation cycle play a vital role. 相似文献
78.
Subramanya K. Bhat J. Keshavayya Venkatrao H. Kulkarni Venugoapala K. R. Reddy Preeti V. Kulkarni Anandrao R. Kulkarni 《应用聚合物科学杂志》2012,125(3):1736-1744
In this work, we attempted to develop a simple and inexpensive colon specific pulsatile drug-delivery system using chitosan microspheres loaded with 5-fluorouracil (5-FU) using an enteric-coated soft gelatin capsule. Chemical crosslinking by glutaraldehyde and interactions between the polymer and the drug were determined by Fourier transform infrared spectral study. Scanning electron microscopy of the microspheres revealed spherical shapes with smooth surfaces. Differential scanning calorimetry studies confirmed the molecular dispersion of the drug in the polymer matrix. Three different formulations (i.e., F1, F2, and F3) were prepared by the variation of the amount of 5-FU. Encapsulation efficiencies of 5.5, 10.8, and 17.9% for drug loadings of 10, 20, and 50%, respectively, were obtained. In vitro release studies were conducted at pH 1.2 and pH 7.4 (to simulate actual gastrointestinal fluid and gastrointestinal tract conditions, respectively). The results indicate that chitosan microspheres released 5-FU in both acidic (60%) and basic pH (40%) conditions, whereas the capsule (filled with chitosan microspheres) showed only 8–10% release in acidic media and nearly 90% in basic media within 12 h. The newly designed pulsatile capsule device could be used for targeting 5-FU to the colon. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
79.
Tailoring magnetic and dielectric properties of rubber ferrite composites containing mixed ferrites 总被引:1,自引:0,他引:1
M. R. Anantharaman K. A. Malini S. Sindhu E. M. Mohammed S. K. Date S. D. Kulkarni P. A. Joy Philip Kurian 《Bulletin of Materials Science》2001,24(6):623-631
Rubber ferrite composites containing various mixed ferrites were prepared for different compositions and various loadings.
The magnetic and dielectric properties of the fillers as well as the ferrite filled matrixes were evaluated separately. The
results are correlated. Simple equations are proposed to predetermine the magnetic and dielectric properties. The validity
of these equations is verified and they are found to be in good agreement. These equations are useful in tailoring the magnetic
and dielectric properties of these composites with predetermined properties. 相似文献
80.
Orthogonal Frequency Division Multiple Access (OFDMA) is an emerging multiple access technology. In this paper, we consider OFDMA in the context of fixed wireless networks. This paper addresses the problem of assigning subcarriers and bits to point-to-point wireless links in the presence of cochannel interference and Rayleigh fading. The objective is to minimize the total transmitted power over the entire network while satisfying the data rate requirement of each link. We formulate this problem as a constrained optimization problem and present centralized algorithms. The simulation results show that our approach results in an efficient assignment of subcarriers and transmitter power levels in terms of the energy required for transmitting each bit of information. However, centralized algorithms require knowledge of the entire network topology and channel characteristics of every link. In a practical scenario, that would not be the situation and there is a need for distributed rate allocation algorithms. To address this need, we also present a distributed algorithm for allocating subcarriers and bits in order to satisfy the rate requirements of the links. 相似文献