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排序方式: 共有428条查询结果,搜索用时 15 毫秒
21.
Muhammad Maqsood Tanveer Hussain Yasir Nawab Khubab Shaker Muhammad Umair 《纺织学会志》2013,104(11):1180-1189
The aim of this study was to develop statistical models for the prediction of warp and weft crimp percentage of cotton woven fabrics. The developed models are based on the empirical data obtained from carefully developed 60 fabric samples with different yarn linear densities, fabric densities, and weave designs. The predictability and accuracy of the developed models was assessed by correlation analysis of the predicted and actual crimp values of another set of eight fabric samples which was not used for the development of models. The results show fairly good capability and accuracy of the prediction models. 相似文献
22.
Sajid Husain G. S. R. Sastry N. Prasada Raju 《Journal of the American Oil Chemists' Society》1991,68(11):822-826
A simple method for quality assessment of heated oils and fats is described. The proposed method involves precise determination
of molecular weight averages (MWA)viz., the weight average molecular weight (
), the number average molecular weight (
) and the Z-average molecular weight (
) by high performance size exclusion chromatography (HPSEC) and their quantitative correlation to percent polar material obtained
by column chromatography (CC). Change in MWA on heat treatment of fourteen different edible oils and fats at 180° ± 2°C for
eight 8-hr days is studied. Relative standard deviations and regression coefficients of correlation between MWA and their
ratios (
, {
}, {
}, {
}, {
} and {
)vs percent polar material have been reported. Probable discard time was predicted for all the oils based on the above-mentioned
correlations and also from the percent of high molecular weight (H. Mwt) species formed. It was observed that the oils which
are generally recommended for coronary patients deteriorated faster. A possibility of extending this methodology to the frying
oils is suggested.
Part of the work was presented at “40th Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy” at Georgia
World Congress Centre, USA, 1989.
IICT Communication No. 2630. 相似文献
23.
24.
Enhancement of Thermoelectric Performance in Hierarchical Mesoscopic Oxide Composites of Ca3Co4O9 and La0.8Sr0.2CoO3 下载免费PDF全文
Sajid Butt Wei Xu Muhammad U. Farooq Guang K. Ren Fida Mohmed Yuanhua Lin Ce‐Wen Nan 《Journal of the American Ceramic Society》2015,98(4):1230-1235
The natural contradiction in enhancing electrical conductivity and thermopower in thermoelectric oxides makes it hard to improve the performance of a single thermoelectric oxide material. We report a facile method to construct a unique architecture of thermoelectric oxides that is promising to realize a simultaneous improvement of overall electrical conductivity and thermopower. Here, a series of two‐phase nanocomposites comprising of Ca3Co4O9 (CCO) and La0.8Sr0.2CoO3 (LSCO) has been synthesized through ball milling followed by spark plasma sintering (SPS) method. The electron microscope images reveal that the two constituents form the unique composites while retaining their individual crystalline and morphological identities. Owing to the hierarchical mesoscopic structure with nanoscale particles and submicrometer scale grain boundaries, an external strain is induced into the CCO grains by the LSCO nanoparticles to enhance the thermopower. The mesoscopic structure is also favorable for improving the electrical conductivity. Moreover, the long‐wavelength phonons can be scattered effectively from LSCO nanoparticles and the thermal conductivity is further suppressed. With compromises between power factor and thermal conductivity, the largest ZT achieved is up to 0.41 at 1000 K for the composites with 25 wt% of LSCO. 相似文献
25.
Ho2Si2O7 material exists in four polymorphs, a triclinic low temperature phase (type-B), a monoclinic modification (type-C), high temperature monoclinic (type-D), and high temperature orthorhombic modification (type-E). The structural properties are measured by XRD and the morphology is noted through scanning electron microscopy (SEM). The dc electrical resistivity (ρ) as a function of temperature and dielectric properties of C-type Ho2Si2O7 in the microwave region is measured. The activation energy is calculated from ln ρ versus 1/kBT plot. The activation energy is 0.119 ± 0.001 eV. Both the real (?′) and imaginary parts of permittivity (?″) decrease slightly as the frequency increases up to 1.5 GHz, after that ?′ increases while ?″ decreases as the frequency increases. At around 2.45 GHz, resonance is observed. 相似文献
26.
M. Mumtaz Liaqat Ali M. Nasir Khan M. Usman Sajid 《Journal of Superconductivity and Novel Magnetism》2016,29(5):1181-1186
Nickel ferrite (NiFe2O4) nanoparticles and Cu0.5Tl0.5Ba2Ca2Cu3O10?δ (CuTl-1223) superconductor were prepared separately and then mixed in an appropriate ratios at the final stage to obtain (NiFe2O4) x /CuTl-1223 (x = 0, 0.5, and 1.0 wt%) nano-superconductor composites. There was no significant change observed in crystal structure of the host CuTl-1223 superconducting matrix after the addition of NiFe2O4 nanoparticles. The value of zero-resistivity critical temperature { T c(R = 0) (K)} was decreased with increasing content of these nanoparticles in these composites. Maximum values of dielectric loss tangent (tanδ) at lowest possible frequency of 40 Hz were increased with the increase of operating temperature, while its values were decreased and become almost zero at higher frequencies for all these samples at all operating temperatures. A peak in dielectric loss tangent was shifted towards lower frequency values with the addition of these nanoparticles in CuTl-1223 superconducting matrix. The dielectric loss tangent peak was also shifted towards lower frequency values in all these samples with increasing operating temperature, which shows the relaxator-like behavior in these samples. The dielectric parameters of these composites can be tuned by frequency, operating temperatures, and nature and content of these nanoparticles. 相似文献
27.
Mohammad Al-Amri Sajid Qamar Shahid Qamar M. Suhail Zubairy 《Quantum Information Processing》2009,8(6):587-605
Recent studies show that macroscopic entangled states of the radiation field can be generated using correlated spontaneous
emission lasers (CEL) even in the presence of cavity losses. Some of the basic schemes based on two-photon CEL and quantum
beat laser (QBL) are reviewed in this article. 相似文献
28.
29.
Changhoon Lee Sangjin Lee Jong Hyuk Park Sajid Hussain Jun Hwan Song 《Telecommunication Systems》2010,44(3-4):267-279
DDP-64, based on various controlled operations, is a 64-bit Feistel-like block cipher consisting of 10 rounds with a 128-bit key. It was designed to attempt to have a high security level and a high speed performance in hardware on ubiquitous computing systems and multimedia. In this paper, however, we show that DDP-64 doesn’t have a high security level, more precisely, we show that it is vulnerable to related-key differential attack. This attack, which is much faster than the key exhaustive search, requires about 254 data and 254 time complexities. This work is the first known cryptanalytic result on DDP-64 so far. 相似文献
30.
Sajid Bashir Muhammad Naeem Adnan Ahmed Khan Syed Ismail Shah 《International Journal of Communication Systems》2010,23(1):109-124
The paper discusses a sequence detector based on univariate marginal distribution algorithm (UMDA) that jointly estimates the symbols transmitted in a multiple input multiple output (MIMO) communication system. While an optimal maximum likelihood detection using an exhaustive search method is prohibitively complex, it has been shown that sphere decoder (SD) achieves the optimal bit error rate (BER) performance with polynomial time complexity for smaller array sizes. However, the worst‐case complexity of SD is exponential in the problem dimensions, this brings in question its practical implementation for larger number of spatial layers and for higher‐order signal constellation. The proposed detector shows promising results for this overly difficult and complicated operating environment, confirmed through simulation results. A performance comparison of the UMDA detector with SD is presented for higher‐order complex MIMO architectures with limited average transmit power. The proposed detector achieves substantial performance gain for higher‐order systems attaining a near optimal BER performance with reduced computational complexity as compared with SD. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献