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991.
992.
Nazir R Mazhar M Akhtar MJ Raza Shah M Khan NA Nadeem M Siddique M Mehmood M Butt NM 《Nanotechnology》2008,19(18):185608
Iron-palladium nanoalloy in the particle size range of 15-30?nm is synthesized by the relatively low temperature thermal decomposition of coprecipitated [Fe(Bipy)(3)]Cl(2) and [Pd(Bipy)(3)]Cl(2) in an inert ambient of dry argon gas. The silvery black Fe-Pd alloy nanoparticles are air-stable and have been characterized by EDX-RF, XRD, AFM, TEM, magnetometry, (57)Fe M?ssbauer and impedance spectroscopy. This Fe-Pd nanoalloy is in single phase and contains iron sites having up to 11 nearest-neighboring atoms. It is superparamagnetic in nature with high magnetic susceptibility, low coercivity and hyperfine field. 相似文献
993.
994.
Although meteorological drought indices are considered as important tools for drought monitoring, they are embedded with different theoretical and experimental structures. Regarding the different geographic and climatic conditions around the world, the most meteorological drought indices have been commonly applied for drought monitoring in different parts of the world. Interestingly, it is observed that such indices in the published studies on drought monitoring have usually yielded inconsistent performance. On the other hand, most studies on drought monitoring as well as the performance of drought indices has been based on short-term historical data (less than 50 years). Therefore, this study aimed to analyze and compare the performance of three common indices of SPI, RAI and PNPI to predict long-term drought events using the Monte Carlo procedure and historical data. To do this end, the 50-year recorded or historical rainfall data across 11 synoptic stations in the Northwest of Iran were employed to generate 1000 synthetic data series so that the characteristics of long-term drought might be determined and the performance of those three indices might be analyzed and compared. The results indicated a very high comparative advantage of the SPI in terms of yielding a satisfactory and detailed analysis to determine the characteristics of long-term drought. Also, the RAI indicated significant deviations from normalized natural processes. However, these results could not reasonably and sufficiently predict long-term drought. Finally, the PNPI was determined as the most uncertain and spatial index (depending on average or coefficient of variation of rainfall data) in drought monitoring. 相似文献
995.
The organic field-effect transistor having 2,3 benzanthracene as active layer grown on SiO2 dielectric layer was fabricated. AFM results indicate that 2,3 benzanthracene thin film is formed from homogeneous small crystal grains with an average diameter about 200 nm. The electrical parameters such as mobility, threshold voltage, Ion/Ioff ratio and SS value were determined. The obtained Ion/Ioff and S values increase with visible light illumination due to more photogenerated charges. The mobility and threshold values were changed by visible light illumination. The organic thin film transistor exhibits a photovoltaic effect in turn-on state. The control of the threshold voltage of 2,3 benzanthracene-based organic thin film transistor was achieved by visible light illumination. The change in the threshold voltage is enough for the electronic technology applications of organic thin film transistors. 相似文献
996.
Rizwan Zafar Kyung Soo Lee Hak Bin Kim Byung Joo Jeon 《Polymer-Plastics Technology and Engineering》2013,52(11):1187-1192
Shrinkage is a common problem in injection-molded parts. This study finds a way to reduce the linear and volumetric shrinkage by using microcellular foaming process. Experiments were conducted by using unfilled and filled (25% short glass fiber reinforced) acetal copolymer samples to demonstrate the effect. The overall improvement in shrinkage was observed therefore the result of increasing weight reduction in the samples. Therefore weight reduction can be utilized to achieve higher-dimensional tolerances of polymer parts and filled polymer can be used if greater mechanical properties are also a matter of concern. 相似文献
997.
998.
M. U. Beg B. Gevao N. Al-Jandal K. R. Beg S. A. Butt L. N. Ali 《Polycyclic Aromatic Compounds》2013,33(2):75-89
The study reports levels of parent polycyclic aromatic hydrocarbons (PAHs) in three native fish species—mullet, sea bream and tonguesole—captured from Kuwait Bay (KB) area and outside the Bay from the Auha area between October 2004 and June 2005. KB has witnessed rapid urban and industrial development since the discovery of oil and is considered to be the most productive area in the region. Whole fish analysis revealed that the lower molecular weight PAHs (pyrene, fluoranthene and phenanthrene) were present in all the three varieties of fish in considerably higher amounts. Other low molecular weight PAHs like acenaphthylene, acenaphthene and anthracene were also present but in lower concentrations. Among the higher molecular weight PAHs, the frequency of detection of benzo(a)anthracene and chrysene was high and were present in high concentrations, whereas Benzo(k)fluoranthene and benzo(a)pyrene were not frequent in detection. The contamination of Σ PAHs was higher in the winter season in mullet and sea bream but in tonguesole a reverse pattern was found. Tonguesole from KB had the highest Σ PAHs suggesting that this bottom dwelling species can be used as an indicator of sediment pollution in the area. The observed seasonality in ∑ PAHs concentration in fish coupled with species difference may be related to difference in metabolic disposition of pollutants and their habitats. 相似文献
999.
The formulation of optimal control problems governed by Cauchy-Riemann equations is presented. A distributed control mechanism
through divergence and curl sources is considered with the boundary conditions of mixed type. A Lagrange multiplier framework
is introduced to characterize the solution to Cauchy-Riemann optimal control problems as the solution of an optimality system
of four first-order partial differential equations and two optimality conditions. To solve the optimality system, staggered
grids and multigrid methods are investigated. It results that staggered grids provide a natural collocation of the optimization
variables and second-order accurate solutions are obtained. The proposed multigrid scheme is based on a coarsening by a factor
of three that results in a nested hierarchy of staggered grids. On these grids a distributed-Gauss-Seidel and gradient-based
smoothing scheme is employed. Results of numerical experiments validate the proposed optimal control formulation and demonstrate
the effectiveness of the staggered-grids multigrid solution procedure. 相似文献
1000.