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671.
Yusuf Kayali Yelda Akcin Ersan Mertgenc Barış Gokce 《Protection of Metals and Physical Chemistry of Surfaces》2017,53(1):127-132
In this study, kinetics of borided ductile iron and lameller graphite grey cast iron were investigated by processing boronizing treatment (was carried out in Ekobor-II powders). The process temperatures and durations respectively 1123, 1173, 1223 K for 2, 4 and 6 hours, with pack boronizing method and under atmospheric pressure in electrical resistance furnace. Changing of borided layer properties was investigated by using optical and scanning electron microscopy, X-ray diffraction and micro-Vickers hardness testers. The growth kinetics of the boride layers forming and thickness of boride layer were computed for both cast iron. The main phases for two processes Fe2B and FeB were defined on the surface. 相似文献
672.
The determination of optimum thickness of insulation is often applied to energy technologies and building projects. In this study, the energy, economic and environmental evaluations of thermal insulation in district heating pipeline are discussed. The optimum insulation thickness, energy saving over a lifetime of 10 years, payback period and emissions of CO2, CO and SO2 are calculated for nominal pipe sizes and fuel types based on heating loads in Afyonkarahisar/Turkey. The life cycle cost analysis is used to determine the optimum thickness of the pipeline material in order to take into account the change in inflation that directly affect both the cost of pipeline material and fuels depending on fuel type. The results show that the highest value of optimum insulation thickness, energy savings, emissions and the lowest payback period are reached for a nominal pipe size of 200 mm. About three times more energy saving results by making 200 mm nominal pipe instead of 50 mm. Considering the economical and environmental advantages, the geothermal energy is a better choice and then fuel-oil. When thermal insulation is done in a district heating pipeline, there will be a significant reduction of 21% in the amount of CO2 emitted to the atmosphere. 相似文献
673.
Identifying the building parameters that significantly impact energy performance is an important step for enabling the reduction of the heating and cooling energy loads of apartment buildings in the design stage. Implementing passive design techniques for these buildings is not a simple task in most dense cities; their energy performance usually depends on uncertainties in the local climate and many building parameters, such as window size, zone height, and features of materials. For this paper, a sensitivity analysis was performed to determine the most significant parameters for buildings in hot-humid climates by considering the design of an existing apartment building in Izmir, Turkey. The Monte Carlo method is selected for sensitivity and uncertainty analyses with the Latin hypercube sampling (LHC) technique. The results show that the sensitivity of parameters in apartment buildings varies based on the purpose of the energy loads and locations in the building, such as the ground, intermediate, and top floors. In addition, the total window area, the heat transfer coefficient (U) and the solar heat gain coefficient (SHGC) of the glazing based on the orientation have the most considerable influence on the energy performance of apartment buildings in hot-humid climates. 相似文献
674.
Polyvinyl alcohol (PVA) electrospun nanofibers and boric acid (BA) complexes of these nanofibers were synthesized with and without using TritonX-100(TX-100) as a water soluble surfactant (PVA, PVA/BA, PVA/TX-100, PVA/TX-100/BA). The electrospun nanofibers were characterized by SEM, FTIR and TGA. Preliminary results showed that certain amount of boric acid decreased the number of Stapylococcus aureus from 6,8x107(CFU/mL) to 3x107(CFU/mL). In the preparation of polymer, boric acid was used as a crosslinker and antimicrobial agent whereas TX-100 was used as surfactant. The viscosity and conductivity measurements indicated that the BA increased viscosity but decreased conductivity. In contrast, TX-100 increased conductivity without considerable effect on viscosity, which affects the production and resulting nanofiber properties such as diameter and bead formation. The antimicrobial activities of the nanofibers were assayed in vitro by Gram-negative (E. coli) and Gram-positive(S. aureus) bacteria. It was observed that PVA/TX-100/BA showed better antibacterial activity against S.aureus bacteria compared to PVA and PVA/TX-100 nanofibers. 相似文献
675.
Yusuf?OysalEmail author Yasar?Becerikli A.?Ferit?Konar 《Journal of Intelligent Manufacturing》2005,16(6):703-714
Fuzzy logic and neural networks are two important technologies for modeling and control of dynamical systems and have been
constrained by the non-dynamical nature of their some popular architectures. There exist problems such as large rule bases
(i.e., curse of dimensionality), long training times, the need to determine buffer lengths. This article proposes to overcome
these major problems in phase portrait modeling of a nonlinear system with a dynamic fuzzy network (DFN) with unconstrained
connectivity and with dynamic fuzzy processing units called “feurons”. Nonlinear physical system properties can be encapsulated
by DFN. As an example, DFN has been used as the modeler for some nonlinear physical system such as chaotic, limit cycle, oscillator.
The minimization of an integral quadratic performance index subject to dynamic equality constraints is considered for a phase
portrait modeling application. For gradient computation adjoint sensitivity method has been used. Its computational complexity
is significantly less than direct sensitivity method, but it requires a backward integration capability. We used first and
approximate second order gradient-based methods including Broyden–Fletcher–Golfarb–Shanno algorithm to update the parameters
of the dynamic fuzzy networks yielding faster rate of convergence 相似文献
676.
Field trials were conducted at Samaru over a three-year period (1980–82) to study the yield, growth and nutrient concentration of three grain sorghum varieties (L. 187, SK5912 and FFBL) in relation to potassium fertilization in a savanna soil. Potassium application rates were 0, 25, 50 and 75 kg K ha–1. Year × potassium interactions were not significant although there were significant variety × K interactions. The highest grain yields for var. L.187, SK5912 and FFBL occurred from the application of 25, 50 and 75 kg K ha–1 respectively. Straw yield was generally increased by K application, which also promoted tillering and hastened flowering in grain sorghum. Although grain weight per head, head number per m2, grain number and 1000-grain weight were unaffected by this nutrient, weight per head was reduced by 22.8 per cent. K application enhanced N concentration of sorghum plants but caused decline in P concentration. The highest K rate gave the highest K concentration in each of the three varieties at 7 weeks after planting. Optimum K requirement of grain sorghum would seem to be between 25 and 50 kg K ha–1. 相似文献
677.
Anwar?T?MerchantEmail author Mahshid?Dehghan Jephat?Chifamba Getrude?Terera Salim?Yusuf 《Nutrition journal》2005,4(1):37
Background
There is little information in the literature on methods of food composition database development to calculate nutrient intake from food frequency questionnaire (FFQ) data. The aim of this study is to describe the development of an FFQ and a food composition table to calculate nutrient intake in a Black Zimbabwean population. 相似文献678.
Ismail?Din?erEmail author Altay?Acar Ibrahim??obano?lu Yusuf?Uras 《Bulletin of Engineering Geology and the Environment》2004,63(2):141-148
Volcanic rocks from the Bodrum Peninsula have been studied to establish a relationship between the uniaxial compressive strength (UCS), Youngs modulus (E) and Schmidt hammer rebound number (N). Test results obtained on andesites, basalts and tuffs have been assessed statistically and the parameters obtained correlated. Regression equations were established between N, E and UCS.The study suggests the following empirical relationships: UCS=2.75 N–36.83, E=0.17 UCS+0.28 and E=0.47 N–6.25. The relationships are somewhat different from the correlations suggested by previous studies and should therefore be used only for andesites, basalts and tuffs with degrees of weathering and mineralogical structure similar to those used in the present study. The results obtained using solely the Schmidt hammer test for estimating mechanical properties of rocks are less accurate than when a full suite of laboratory tests is carried out but it is hoped that these empirical equations will help geotechnical engineers making practical decisions at a preliminary site investigation stage. 相似文献
679.
LG Boros J Puigjaner M Cascante WN Lee JL Brandes S Bassilian FI Yusuf RD Williams P Muscarella WS Melvin WJ Schirmer 《Canadian Metallurgical Quarterly》1997,57(19):4242-4248
This study investigates the significance of the glucose-6-phosphate dehydrogenase (G6PD) catalyzed oxidative and the transketolase (TK) catalyzed nonoxidative pentose cycle (PC) reactions in the tumor proliferation process by characterizing tumor growth patterns and synthesis of the RNA ribose moiety in the presence of respective inhibitors of G6PD and TK. Mass spectra analysis of 13C-labeled carbons revealed that these PC reactions contribute to over 85% of de novo ribose synthesis in RNA from [1,2-(13)C]glucose in cultured Mia pancreatic adenocarcinoma cells, with the fraction synthesized through the TK pathway predominating (85%). Five days of treatment with the TK inhibitor oxythiamine (OT) and the G6PD inhibitor dehydroepiandrosterone-sulfate (0.5 microM each) exerted a 39 and a 23% maximum inhibitory effect on cell proliferation in culture, which was increased to 60% when the two drugs were administered in combination. In vivo testing of 400 mg/kg OT or dehydroepiandrosterone-sulfate in C57BL/6 mice hosting Ehrlich's ascitic tumor cells revealed a 90.4 and a 46% decrease in the final tumor mass after 3 days of treatment. RNA ribose fractional synthesis through the TK reaction using metabolites directly from glycolysis declined by 9.1 and 23.9% after OT or the combined treatment, respectively. Nonoxidative PC reactions play a central regulating role in the carbon-recruiting process toward de novo nucleic acid ribose synthesis and cell proliferation in vitro and in vivo. Therefore, enzymes or substrates regulating the nonoxidative synthesis of ribose could also be the sites to preferentially target tumor cell proliferation by new anticancer drugs. 相似文献
680.
Solvent penetration into nonaqueous dispersions (NAD) of poly(methyl methacrylate) (PMMA) sterically stabilized by PIB were studied by ESR spectroscopy. These colloidal particles were exposed to dilute solution of spin probe 3-carbomoyl 2,2,5,5-tetramethyl 3-pyrolin-1-yloxy and the bimodal distribution of ESR spectra of this probe molecules were carefully monitored as a function of time. Fickian type diffusion of spin probes into the particles was observed and a spherical model was employed to obtain the diffusion coefficients (D) in various solvents. D values were found around 10?15 cm2/s, and interpreted as the parameter, inversely proportional to the apparent viscosity of the environment inside the colloid particle. Maximum amount of diffused solvent molecules (M∞) into the PMMA particle was found inversely proportional to polymer-solvent interaction through the solubility parameters. The interconnected network of PIB was found to be responsible for the penetration of spin-probe (i.e., solvent) molecules into the glassy PMMA phase and/or PIB-PMMA interface. 相似文献