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81.
Some structural properties of CdO:F films produced by ultrasonic spray pyrolysis method 总被引:1,自引:0,他引:1
The fluorine doped cadmium oxide (CdO:F) samples have been deposited at 250 °C by ultrasonic spray pyrolysis method. Cadmiumacetat-dihydrat and ammonium fluoride have been taken as a source of cadmium and fluorine-dopant respectively. The thickness of the CdO:F samples was about 1.4 μm. X-ray diffraction pattern of the CdO:F samples has revealed that the samples are polycrystalline with cubic sodium chloride structure. There are shifts of the d values (interplanar spacing) for CdO:F samples with respect to standard CdO film. The lattice parameters for cubic structure have been calculated using the Bragg equation. The texture coefficients calculated for various planes at different fluorine concentrations indicate that the samples have exhibited (111) and (200) preferential orientations. 相似文献
82.
A new Schiff base, 4-((6-ethoxybenzothiazole-2-ylimino)methyl)benzene-1,2-diol (3,4-HBAEBT) was synthesized by the condensation reaction of 3,4-dihydroxybenzaldehyde (3,4-HBA) and 2-amino-6-ethoxybenzothiazole. The Schiff base, then, was converted to its polymer derivatives by oxidative polycondensation reaction in both organic (P-1) and aqueous alkaline medium (P-2). Spectral observations indicated different structural properties for each polymerization condition. Organic and aqueous alkaline medium produced poly(ether) and poly(phenol) structures, respectively. The obtained polymers were separately studied with respect to optical, electrochemical, electrical and thermal properties. With exception of thermal degradation behaviors, the other investigated properties as well as morphological characteristics of both polymers were considerably different. In the fluorescence measurements a solvatochromic effect was recorded and the emission colors of the polymers could be changed as turquoise-green by solvent change. 相似文献
83.
F Ildan S Polat AI G?cer A Oner T Isbir UO Mete M Kaya A Karadayi 《Canadian Metallurgical Quarterly》1996,138(3):338-345
The sodium-potassium activated and magnesium dependent adenosine-5'-triphosphatase (Na(+)-K(+)/Mg(+2) ATPase EC.3.6.1.3.) activity and lipid peroxidation and early ultrastructural findings were determined in rat brain at the acute stage of ischaemia produced by permanent unilateral occlusion of the middle cerebral artery (MCA). The effects of the pretreatment with intravenous high-dose methylprednisolone (MP) on these biochemical indices and ultrastructural findings were also evaluated in the same model. The rats were divided into four groups. In group I, 10 rats were used to determine Na(+)-K(+)/Mg(+2) ATPase activity and the extent of lipid peroxidation by measuring the malondialdehyde (MDA) content and normal ultrastructural findings. In group II on 20 rats, only subtemporal craniectomy was done in order to determine the effects of the surgical procedure on these indices and findings. This group was treated intravenously with saline solution before occlusion. In group III with MCA occlusion, saline solution was administered intravenously to 20 rats in the same amount of methylprednisolone used in group IV, ten minutes before the occlusion. In Group IV, a single high-dose (30 mg/kg) of methylprednisolone was administered intravenously, ten minutes before occlusion in 20 rats. After occlusion of the middle cerebral artery, Na(+)-K(+)/Mg(+2) ATPase activity was decreased promptly in the first ten minutes in the ischaemic hemisphere and remained at a lower level than the contralateral hemispheres in the same group and the normal levels in group I, during 120 minutes of ischaemia. A single dose methylprednisolone pretreatment prohibited the inactivation of Na(+)-K(+)/Mg(+2) ATPase. On the other hand, there was significant difference in malondialdehyde content between group I and group III. Malondialdehyde levels were significantly increased following ischaemia and a non-significant increase was observed in the contralateral hemisphere. Methylprednisolone treatment significantly decreased malondialdehyde content on the side of the ischaemic hemisphere. We conclude that there is a positive relationship between membrane-bound enzyme Na(+)-K(+)/Mg(+2) ATPase activity, malondialdehyde content and early ultrastructural changes in the treated group with MP. These data suggest that the pretreatment injection of high doses (30 mg/kg) methylprednisolone contribute to the protection of the brain from ischaemia with stabilization of the cell membrane by effecting the lipid peroxidation and the activation of Na(+)-K(+)/Mg(+2) ATPase. 相似文献
84.
Computation of approximate optimal policies in a partially observed inventory model with rain checks
Alain Bensoussan Metin Cakanyildirim Suresh P. Sethi Ruixia ShiAuthor vitae 《Automatica》2011,(8):1589-1604
This paper proposes a new methodology to solve partially observed inventory problems. Generally, these problems have infinite-dimensional states that are conditional distributions of the inventory level. Our methodology involves linearizing the state transitions via unnormalized probabilities. It then uses an appropriate functional basis to represent the state. Considering the speed and stability of computations, we choose truncated Chebyshev polynomials as the basis. We use Fast Fourier Transforms along with an appropriate discretization of inventory levels to speed up the computations. These main ideas are blended to obtain an iterative algorithm to solve a partially observed inventory model with rain checks. In this model, the inventory manager (IM) does not know the inventory level when it is positive. Otherwise, the IM fully observes it. This model provides a context to illustrate our methodology, which applies to other such models. Although this model has been studied mathematically in the literature, the use of our algorithm provides a numerical approximation of the optimal order quantities. These are compared to the orders released under a base mean-stock policy, where the IM replaces the unobserved inventory level with its mean and applies the well-known base stock policy. We show numerically that the optimal order quantity is very close to the base mean-stock order quantity, when the variance of the inventory distribution is small. When the mean of the inventory distribution is large, the optimal order quantity is more than the base mean-stock quantity, and it is the other way around when the mean is small or negative. These insights are explained via uncertainty and information effects and their interplay. We expect this interplay to show up in other partially observed inventory models. 相似文献
85.
Synthesis and characterization of poly(N-(2-(thiophen-3-yl)methylcarbonyloxyethyl)maleimide) and its spectroelectrochemical properties 总被引:1,自引:0,他引:1
A new monomer; N-(2-(thiophen-3-yl)methylcarbonyloxyethyl) maleimide (NMT) was synthesized. The chemical structure of the
monomer was characterized by Nuclear Magnetic Resonance (1H-NMR) and Fourier Transform Infrared (FTIR) Spectroscopy. Electrochemical polymerization of NMT was performed in acetonitrile
(AN)/borontrifloride ethylether (BFEE) solvent mixture (1:1, v/v) where tetrabutylammonium tetrafluoroborate (TBAFB) was utilized
as the supporting electrolyte. The resulting conducting polymer was characterized by Fourier Transform Infrared (FTIR) Spectroscopy,
thermal analyses and Scanning Electron Microscopy (SEM). Electrical conductivity was measured by the four-probe technique.
The spectroelectrochemical behavior and switching ability of P(NMT) film were investigated by UV–Vis spectrophotometry. P(NMT)
revealed color changes between yellow and blue in the reduced and oxidized states respectively. 相似文献
86.
Optimization of Multireservoir Systems by Genetic Algorithm 总被引:1,自引:1,他引:0
Application of optimization techniques for determining the optimal operating policy of reservoirs is a major issue in water
resources planning and management. As an optimization Genetic Algorithm, ruled by evolution techniques, have become popular
in diversified fields of science. The main aim of this study is to explore the efficiency and effectiveness of genetic algorithm
in optimization of multi-reservoirs. A computer code has been constructed for this purpose and verified by means of a reference
problem with a known global optimum. Three reservoirs in the Colorado River Storage Project were optimized for maximization
of energy production. Besides, a real-time approach utilizing a blend of online and a posteriori data was proposed. The results
obtained were compared to the real operational data and genetic algorithm was found to be effective and can be utilized as
an alternative technique to other traditional optimization techniques. 相似文献
87.
88.
Determination of photoinitiated polymerization of multifunctional acrylates with acetic acid derivatives of thioxanthone by RT-FTIR 总被引:1,自引:0,他引:1
Feyza Karasu Meral AydinM. Arif Kaya Demet Karaca BaltaNergis Arsu 《Progress in Organic Coatings》2009
Photopolymerization of multifunctional acrylates with 2-thioxanthone-thioacetic acid (TXSCH2COOH) and 2-(carboxymethoxy) thioxanthone (TXOCH2COOH) as the one-component photoinitiator has been investigated by real-time Fourier transform infrared (RT-FTIR) spectroscopy. The photobleaching of these one-component nature initiators was performed in air. The irradiation time for total bleaching was 240 s for TXSCH2COOH and 540 s for TXOCH2COOH. 相似文献
89.
Environmental concerns and limited resource of petroleum fuels have caused interests in the development of alternative fuels for internal combustion (IC) engines. For diesel engines, alcohols are receiving increasing attention because they are oxygenated and renewable fuels. Therefore, in this study, the effect of injection timing on the exhaust emissions of a single cylinder, naturally aspirated, four-stroke, direct injection diesel engine has been experimentally investigated by using methanol-blended diesel fuel from 0% to 15% with an increment of 5%. The tests were conducted for three different injection timings (15°, 20° and 25 °CA BTDC) at four different engine loads (5 Nm, 10 Nm, 15 Nm, 20 Nm) at 2200 rpm. The experimental test results showed that Bsfc, NOx and CO2 emissions increased as BTE, smoke opacity, CO and UHC emissions decreased with increasing amount of methanol in the fuel mixture. When compared the results to those of original injection timing, NOx and CO2 emissions decreased, smoke opacity, UHC and CO emissions increased for the retarded injection timing (15 °CA BTDC). On the other hand, with the advanced injection timing (25 °CA BTDC), decreasing smoke opacity, UHC and CO emissions diminished, and NOx and CO2 emissions boosted at all test conditions. In terms of Bsfc and BTE, retarded and advanced injection timings gave negative results for all fuel blends in all engine loads. 相似文献
90.
N. Maral K. Keliolu B. Arslan H. Kaya E. adrl 《Journal of Materials Processing Technology》2008,202(1-3):145-155
Succinonitrile (SCN)–7.5 wt.% carbon tetrabromide (CTB) alloy was unidirectionally solidified with a constant growth rate (V = 33 μm/s) at five different temperature gradients (G = 4.1–7.6 K/mm) and with a constant temperature gradient (G = 7.6 K/mm) at five different growth rates (V = 7.2–116.7 μm/s). The primary dendrite arm spacings, secondary dendrite arm spacings, dendrite tip radius and mushy zone depths were measured. Theoretical models for the microstructure parameters have been compared with the experimental observations, and a comparison of our results with the current theoretical models and previous experimental results have also been made. 相似文献