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141.
Murat Erhan Balci 《电力部件与系统》2014,42(14):1565-1575
The main purpose of this article is to employ the C-type passive filters for maximization of the loading capability of transformers under non-sinusoidal conditions. For this aim, an optimal passive filter design approach is proposed regarding minimization of the harmonic loss factor (FHL), which is defined in IEEE standard C57.110 to represent the loading capability of the transformers supplying non-sinusoidal load currents. With respect to IEEE standard 519, displacement power factor and individual harmonics & total harmonic distortions of the voltage and current are considered as constraints of the proposed optimal filter design approach. In addition, numerical results are presented to figure out that the proposed approach provides higher loading capability of the transformers under non-sinusoidal conditions when compared with the other two optimal filter design approaches based on minimization of the current total harmonic distortion and minimization of the voltage total harmonic distortion. 相似文献
142.
Muge Durmaz Erhan Zor Erdal Kocabas Haluk Bingol Emine G. Akgemci 《Electrochimica acta》2011,56(15):5316
In this study, transfer reactions of alkali and alkaline-earth metal ions across a micro-water/1,2-dichloroethane (1,2-DCE) interface facilitated by a novel calix[4]arene derivative, 5,11,17,23-tetra-tert-butyl-25,27-bis(2′amino-methylpyridine)-26,28-dihydroxy calix[4]arene (APHC4), were investigated by cyclic and differential pulse voltammetry techniques. Well-defined voltammetric behavior was obtained only for K+ ion among the used metal ions. The electrochemical data were used to determine the stoichiometry and the appropriate association constant of the occurring complex between K+ ion and APHC4. The obtained steady-state voltammograms indicated that the facilitated transfer process occurs with a TIC/TID mechanism according to 1:1 stoichiometry. The logarithm of the association constant () of K(APHC4)+ complex in the DCE phase was calculated to be 6.32. Also, the availability of the facilitated transfer for the design of an amperometric screening sensor for K+ ion was evaluated in the range of 50–500 μmol dm−3. 相似文献
143.
Ayhan Demirba Atila aglar Alipa a Ayas Selami Karslioglu 《Petroleum Science and Technology》1996,14(3):395-404
Air dried and ground tea waste was subjected to supercritical and catalytic fluid extraction by using water or acetone as solvent at different temperatures. The most important reactions variables were temperature and ratio of catalyst to the solid sample. The yields of the catalytic fluid reaction have been increased from 70.3 % to 92.4 % as the temperature increased from 230 °C to 340 °C by using water as solvent. The yield of extract was obtained from non catalytic supercritical water extraction was about 50.0 % at380°C. 相似文献
144.
Erhan Güneyisi Mehmet Gesoğlu Turan Özturan Erdoğan Özbay 《Construction and Building Materials》2009,23(1):469-481
In this study, effects of cement type, curing condition, and testing age on the chloride permeability of concrete were investigated experimentally. Chloride permeability of concrete was determined through rapid chloride permeability test (RCPT). The research variables included cement type (i.e. plain and four different blended cements), water–cement ratio (0.65 and 0.45), curing condition (uncontrolled, controlled, and wet curing), and testing age (28, 90, and 180 days). Furthermore, based on the experimental results, a neural network (NN) model-based explicit formulation was proposed to predict the chloride permeability of concrete in terms of the water–cement ratio, aggregate–cement ratio, superplasticizer–cement ratio, cement type, curing condition, and testing age. Finally, proposed NN based explicit formulation was verified by using the data gathered from the literature. The test results indicated that the selected experimental parameters had pronounced effects on the chloride permeability of concretes. Besides, it was found that the empirical model developed by using NN seemed to have a high prediction capability of the chloride permeability of concretes. 相似文献
145.
A random copolymer of N‐isopropyl acrylamide (NIPAAm) and acrylic acid (AAc) with an AAc content of 3.1 ± 0.19 mmol of carboxylic acid groups per gram of the copolymer and with a number‐average molecular weight of 1400 was synthesized by free‐radical polymerization with 2,2′‐azoisobutyronitrile in dimethylformamide. Then, monopeptide, dipeptide, and tripeptide (i.e., alanine) conjugates of this copolymer were prepared with their carboxyl‐end‐protected (with methyl ester hydrochloride) form of alanine, with a water‐soluble carbodiimide. Of the carboxylic acids, 93, 69, and 57% were conjugated (loaded) with alanine at the monopeptide, dipeptide, and tripeptide conjugation steps, respectively. The chemical structures of the copolymer and conjugates were analyzed by Fourier transform infrared and 1H‐NMR, which revealed the conjugate formation. Amino acid conjugation caused significant decreases in the lower critical solution temperatures (LCST) of the copolymer, especially at pH 7.4. The LCST values of the dipeptide and tripeptide conjugates of poly(NIPAAm‐co‐AAc) at both pH 4.0 and 7.4 shifted to significantly higher temperatures. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2012–2019, 2003 相似文献
146.
A parametric study was conducted over Pt–Ni/δ-Al2O3 to explore the effect of Pt and Ni contents on the ethanol steam reforming characteristics of the bimetallic catalyst. Experiments with catalysts having 0.2–0.3 wt%Pt and 10–15 wt%Ni contents indicated that the best ethanol steam reforming performance is achieved over 0.3 wt%Pt–15 wt%Ni/δ-Al2O3. Kinetics of ethanol steam reforming was studied over this catalyst in the 673–823 K interval using differential and integral methods of data analysis. A power-function rate expression was obtained with reaction orders of 1.01 and −0.09 in ethanol and steam, respectively, and the apparent activation energy of ethanol steam reforming over 0.3 wt%Pt–15 wt%Ni/δ-Al2O3 was calculated as 59.3 ± 2.3 kJ mol−1. 相似文献
147.
Improving strength, drying shrinkage, and pore structure of concrete using metakaolin 总被引:4,自引:0,他引:4
This paper presents the results of an investigation on the use of metakaolin (MK) as a supplementary cementing material to
improve the performance of concrete. Two MK replacement levels were employed in the study: 10% and 20% by weight of the Portland
cement used. Plain and PC-MK concretes were designed at two water–cementitious materials (w/cm) ratios of 0.35 and 0.55. The
performance characteristics of the concretes were evaluated by measuring compressive and splitting tensile strengths, water
absorption, drying shrinkage, and weight loss due to the corresponding drying. The porosity and pore size distribution of
the concretes were also examined by using mercury intrusion porosimetry (MIP). Tests were conducted at different ages up to
120 days. The results revealed that the inclusion of MK remarkably reduced the drying shrinkage strain, but increased the
strengths of the concretes in varying magnitudes, depending mainly on the replacement level of MK, w/cm ratio, and age of
testing. It was also found that the ultrafine MK enhanced substantially the pore structure of the concretes and reduced the
content of the harmful large pores, hence made concrete more impervious, especially at a replacement level of 20%. 相似文献
148.
Radical copolymerizations of N-vinyl-2-pyrrolidone (VP) with isostructural
analogs of maleic anhydride (MA), such as citraconic anhydride (CA) and N-substituted
maleimides [maleimide (MI), N-ethylmaleimide (EMI) and N-phenylmaleimide
(PhMI)] were studied. Compositions of copolymers synthesized in a wide range of monomer feed ratios were
determined by alkali titration (for anhydride copolymers), FTIR and 1H NMR spectroscopy
using 1495 and 630 cm-1 (for VP-MI), 1289 and 1225 cm-1
(for VP-EMI) and 1050 and 3067 cm-1 (for VP-PhMI) analytical bands and
integral areas of CH2 (pyrrolidone ring) and CH (MI), CH3
(EMI) and CH= (benzene ring in PhMI) groups, respectively. Electron-donor VP monomer was found to have
substantially different reactivities in the radical copolymerization with MA, CA and N-substituted
(H, C2H5 and phenyl) malemides as electron-acceptor comonomers.
Effects of H-bonding and N→O=C coordination on the monomer reactivity ratios were evaluated. Tendency
to alternation of the monomer pairs increases in the order of VP–MA > VP–CA > VP-MI
> VP-PhMI > VP-EMI. Structure-thermal property-relationship for the synthesized copolymers was
also studied. 相似文献
149.
Babur Ozcelik Emel KuramM. Huseyin Cetin Erhan Demirbas 《Tribology International》2011,44(12):1864-1871
Experimental studies on the performances of both new developed environmental friendly vegetable based cutting fluids (refined sunflower and canola oils) including different percentage of extreme pressure (EP) additive and two commercial cutting fluids (semi-synthetic and mineral cutting fluids) in turning processes were reported in this work. Performances of cutting fluids were compared with respect to surface roughness, cutting and feed forces and tool wear during longitudinal turning of AISI 304L. Experimental results were also compared with dry cutting conditions. The results indicated that 8% of EP included canola based cutting fluid performed better than the rest. 相似文献
150.
Kouroush Salimi Murat Topuzogullari Sevil Dincer Halil Murat Aydin Erhan Piskin 《应用聚合物科学杂志》2016,133(6)
Poly l ‐lactic acid grafted starch (St‐g‐PLA) copolymers were directly synthesized under microwave irradiation by using sodium hydroxide (NaOH) and stannous 2‐ethyl hexanoate acting as a catalyst, without the use of toxic solvents. The product were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (13C CP/MAS NMR), X‐ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA‐DTG). SEM analysis indicated that microwave heating had a considerable effect on the interfacial adhesion between PLA and starch. Thermogravimetric analysis (TGA‐DTG) revealed that copolymers exhibited better thermal stability. Maximum PLA grafting was achieved with the following reaction conditions: 450W microwave power, monomer ratio of 1:5 and 0.4M of NaOH. This study demonstrates that it is possible to obtain St‐g‐PLA copolymers with better processing characteristics and smaller sizes via microwave‐assisted synthesis. The applied procedure is an interesting “green” synthesis method for the production of biodegradable materials used in a diverse range of applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42937. 相似文献