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51.
Engin D. Gezer Ümit C. Yildiz Ali Temiz Sibel Yildiz Eylem Dizman 《Building and Environment》2005,40(12):1684-1688
In this study, the main objective was to asses the distribution of Cu, Cr, and As in soils adjacent to CCA-treated utility poles in Eastern Blacksea Region of Turkey (Trabzon, Rize and Artvin ) and determine the influence of soil composition.
Surface (0–5 cm) and subsurface soil samples (30–40 cm) were collected near CCA-treated utility poles and control soil samples away from CCA-treated utility poles were also collected. Water holding capacity, pH and mechanical properties of soil samples were determined for both depth levels.
Results showed that Cu, Cr and As concentration in soil samples taken from all three cities in 0–5 cm depth was higher than soil samples taken from 30–40 cm depth. Cu, Cr and As concentrations were much higher in soil samples taken from city of Rize 相似文献
52.
The aim of the study is to investigate the correlation between non-destructive measurements and impact toughness of 2024 Al-alloy.
Following the solutionizing at 493 °C/1 h and water quench, the samples were aged at 190 °C for various periods between 0.5 h
and 18 h. Hardness, impact toughness, sound velocity, and electrical conductivity were measured for each specimen group, and
fracture surfaces were investigated by SEM. To focus on only the effect of precipitation, the process variables were minimized
by preparing the samples from the same batch, and applying the identical procedure for solution heat treatment and quenching.
Any cold deformation prior to aging of the samples was not applied. It has been concluded that sound velocity and electrical
conductivity measurements are promising for the determination of variations in the impact toughness of the precipitation hardened
2024 Al-alloy. 相似文献
53.
Effect of Al2O3 Additions on the Thermal Expansion Behavior of a Li2O-ZnO-SiO2 Glass-Ceramic 总被引:1,自引:0,他引:1
Erdem Demirkesen Z. Engin Erkmen Nil Yildiz 《Journal of the American Ceramic Society》1999,82(12):3619-3621
The effect of Al2 O3 substitution on the thermal expansion behavior of a Li2 O-ZnO-SiO2 glass-ceramic was investigated using differential thermal analysis, X-ray diffractometry, and dilatometry. The coefficient of thermal expansion of the original Al2 O3 -free glass-ceramic measured between 20° and 900°C decreased from 12.4 × 10-6 °C-1 to 6.3 × 10-6 °C-1 with Al2 O3 substitution for ZnO up to 11 wt%. The results were correlated to the changes in the phase assemblage with Al2 O3 addition. 相似文献
54.
Emekdas G Aslan G Tezcan S Serin MS Yildiz C Ozturhan H Durmaz R 《International journal of food microbiology》2006,107(3):310-314
The frequency, antibiotic susceptibility, and genotypic discrimination of Aeromonas strains isolated from municipally treated drinking tap water distribution systems were investigated in this study. We have analyzed 148 tap water samples collected from 8 different locations by bacterial cultivation and arbitrarily primed polymerase chain reaction (AP-PCR). Gram negative, hemolytic, oxidase (+) and catalase (+) bacterial colonies were applied to the study. Identification of bacterial colonies was done by conventional biochemical method and API ID 20E panel (BioMerieux-France). Molecular epidemiological discrimination of the isolates was done by AP-PCR. Aeromonas spp. was detected in 6 of 148 (4%) tap water samples from 8 different locations. Five isolates were identified as Aeromonas hydrophila and one isolate was identified as Vibrio fluvialis by conventional biochemical method. These data were also confirmed by API 20E panel. One of 6 isolates was resistant to gentamicin, 2 of 6 isolates were resistant to trimethoprim/sulfamethoxazole, 4 of 6 isolates were resistant to ampicillin and ampicillin-sulbactam and all of 6 isolates were resistant to cephalothin. All isolates were found to be susceptible to amikacin, aztreonam, ceftazidime, ceftriaxone, ciprofloxacin. All 6 strains of Aeromonas were discriminated by AP-PCR and were determined that all isolates were from different genotypic sources. Although the frequency of the isolates was under the standard limits, the results indicate that hemolytic A. hydrophila are present in municipally treated tap water samples in Mersin City. While all strains were genotypically distinct, all of them were resistant to first generation beta lactam antibiotics tested in this study. 相似文献
55.
Xiao Xu Andrew Meade Yildiz Bayazitoglu 《International Journal of Heat and Mass Transfer》2010,53(19-20):4017-4022
The present work introduces an alternative method for calculating the spatial distribution of interstitial fluence rate in laser-induced interstitial thermotherapy. The method originates from the un-simplified integral–differential radiant transport equation, which is then solved by the radial basis function collocation technique. After comparing with the Monte Carlo and finite volume methods, it is concluded that this method is able to provide accurate predictions of fluence rate distributions along the penetration depth, particularly around the boundary. 相似文献
56.
The present paper investigates the performance of a solid oxide fuel cell based on proton-conducting electrolyte (SOFC-H+) using one-dimensional steady-state model. The analysis covers a detailed electro-chemical model for H2 and NH3 fuels. The direct internal reforming of NH3 is examined, and the effects of some operating parameters (e.g. temperature, pressure, fuel utilization and oxidant utilization) on the reversible cell potential are investigated. In addition, the overpotentials (including activation, ohmic and concentration) are calculated to study the irreversible behavior of the SOFC-H+ with some actual data operating conditions and material properties taken from the literature. In addition, effects of some operation and structural parameters on cell performance were examined. The present results indicate that the activation and the ohmic losses are considerable. The concentration overpotential at the anode side is negligible due to the fact that H2O is produced at the cathode side. The maximum power density is calculated as 3212 and 3113 W/m2 at 1073 K and 1 atm for the fuels of H2 and NH3. The results further show that H2 provides better performance than NH3 at the same partial pressure. Moreover, NH3 is an excellent hydrogen carrier which is a potential candidate for SOFC-H+ due to its high hydrogen content and considerable cell performance. 相似文献
57.
Nuh Aydin Suat Karadeniz Bahattin Yildiz 《Applicable Algebra in Engineering, Communication and Computing》2013,24(5):355-367
We consider quasi-cyclic codes over the ring $\mathbb{F }_2+u\mathbb{F }_2+v\mathbb{F }_2+uv\mathbb{F }_2$ , a finite non-chain ring that has been recently studied in coding theory. The Gray images of these codes are shown to be binary quasi-cyclic codes. Using this method we have obtained seventeen new binary quasi-cyclic codes that are new additions to the database of binary quasi-cyclic codes. Moreover, we also obtain a number of binary quasi-cyclic codes with the same parameters as best known binary linear codes that otherwise have more complicated constructions. 相似文献
58.
Advancements in electronic performance result in a decrease in device size and increase in power density. Because of these advancements, current cooling mechanisms for electronic devices are beginning to be ineffective. Within the localized hot spots, the materials of the components are reaching temperature values that can lead to improper functioning of the device. Many techniques have been successful in the past, such as heat sinks, cavities or grooves, micro pin-fins, etc., but still do not provide adequate cooling necessary to maintain temperature values low enough for the electronic components to operate. Microchannels, with their large heat transfer surface to volume ratio, cooled with either gas or liquid coolant, have shown some potential. By modifying the walls of the microchannel with fins, pins, or grooves, the cooling performance can be improved. A possible fin material used to increase the surface area of a microchannel is carbon nanotubes, which possess excellent thermal and mechanical properties. Numerical and computational methods needed to analyze flow at the micro- and nano-scale are also introduced. The numerical methods such as lattice Boltzmann, molecular dynamics, and computational fluid dynamics may lessen the cost and time that often accompany experimentation. 相似文献
59.
A smoothed particle hydrodynamics (SPH) solution to the Rayleigh–Taylor instability (RTI) problem in an incompressible viscous two-phase immiscible fluid with surface tension is presented. The present model is validated by solving Laplace’s law, and square bubble deformation without surface tension whereby it is shown that the implemented SPH discretization does not produce any artificial surface tension. To further validate the numerical model for the RTI problem, results are quantitatively compared with analytical solutions in a linear regime. It is found that the SPH method slightly overestimates the border of instability. The long time evolution of simulations is presented for investigating changes in the topology of rising bubbles and falling spike in RTI, and the computed Froude numbers are compared with previous works. It is shown that the numerical algorithm used in this work is capable of capturing the interface evolution and growth rate in RTI accurately. 相似文献
60.
Multi-objective optimization of vehicle crashworthiness using a new particle swarm based approach 总被引:5,自引:4,他引:1
Ali R. Yildiz Kiran N. Solanki 《The International Journal of Advanced Manufacturing Technology》2012,59(1-4):367-376
Vehicle crashworthiness is an important issue to ensure passengers safety and reduce vehicle costs in the early design stage of vehicle design. The aim of the crashworthiness design is to provide an optimized structure that can absorb the crash energy by controlled vehicle deformations while maintaining enough space of the passenger compartment. Meta-modeling and optimization techniques have been used to reduce the vehicle design cycle. In this paper, a new particle swarm-based optimization method is presented for multi-objective optimization of vehicle crashworthiness. The proposed optimization method is first validated with a multi-objective disk brake problem taken from literature. Finally, it is applied to multi-objective crashworthiness optimization of a full vehicle model and milling optimization problems to demonstrate its effectiveness and validity. 相似文献