A multi-objective genetic algorithm for the hot mix asphalt problem

Neural Computing and Applications - It is desirable for the work done in any construction process to be both cost-effective and durable. A thorough consideration of the matter reveals that the...     

From potential forecast to foresight of Turkey's renewable energy with Delphi approach

A Delphi Survey is a series of questionnaires that allow experts or people with specific knowledge to develop ideas about potential future developments around an issue. The Delphi questionnaires were developed throughout the foresight process in relation to the responses given by participants in bibliometric and SWOT analysis conducted prior to the Delphi survey. In this paper, Turkey's renewable energy future is evaluated using the Delphi method. A two-round Delphi research study was undertaken to determine and measure the expectations of the sector representatives regarding the foresight of renewable energies. First and second round of Delphi study were carried out by using online surveys. About 382 participants responded in the first round of the Delphi questionnaire yielding a respond rate of 20.1%, whereas 325 participants responded at the second round yielding a respond rate of 84.9%. About 50% of Turkey's energy demand was foresighted to be met by renewable energies around 2030. The results showed that all types of renewable energies would not only provide economic and environmental benefits but also improve living standards.     

Naphthalene and o-Xylene Adsorption onto High Carbon Fly Ash

Adsorption is an effective remediation technique for petroleum hydrocarbons because of its ease of use and high efficiency. The utilization of high-carbon content industrial by-products in such applications can present significant economic and environmental advantages. In this study, batch adsorption tests and petrographic analyses were used to investigate the adsorption of two nonpolar petroleum contaminants, naphthalene and o-xylene, onto seven fly ashes with varying carbon contents, with powdered activated carbon (PAC) as a control. Six equilibrium isotherm models were used to evaluate the batch data. The results yielded nonlinear sorption isotherms characterized by high sorption capacity at low concentrations. The naphthalene and o-xylene adsorption capacity of the fly ashes was correlated with the unburned carbon content, specific surface area of the sorbent, and the percentage of the anisotropic and isotropic carbon content of the ash. On the basis of the Polanyi-Dubinin-Manes model, a pore-filling mechanism is the dominant mechanism for the adsorption of the nonpolar organic chemicals onto PAC, whereas the adsorption onto fly ash is likely to be governed by the unburned carbon content and the specific surface area of the ash.     

Determination of dyeing levelness using surface irregularity function

An acceptably dyed fabric must be a match to the target and is visually even in appearance, that is, level. Although color difference measurement can objectively determine whether a match has been achieved, levelness is still determined subjectively, leading to inevitable disagreements between dyer and customer. The levelness of a series of dyed fabrics has been objectively evaluated using a surface irregularity function derived from analysis of digital images of the fabrics. The measurements derived correlate more closely to visual assessment than do K/S measurements. © 2009 Wiley Periodicals, Inc. Col Res Appl, 34, 285–290, 2009     

Effect of shape factor, characteristic length, and boundary conditions on spontaneous imbibition

Spontaneous imbibition is vital for oil recovery in porous media, especially when considering fluid flow behavior in fractured reservoirs. Small-scale laboratory tests on reservoir rock samples show that spontaneous imbibition becomes crucial in estimating field behavior according to oil recovery by imbibition performance. This paper presents experimental work on oil recovery by spontaneous water imbibition on kerosene/brine/Berea systems. The main objectives of this study were to investigate the effect of shape factor (SF), characteristic length (CL), and boundary conditions (BC) on the rate of spontaneous imbibition, and improve oil production simulation by spontaneous imbibition from naturally fractured reservoirs using derived shape factors. General mathematical definitions for shape factor and characteristic length are typically derived using irregular geometric shapes, but this investigation utilized regular geometric shapes of core samples (i.e., cylindrical, square prism, and triangular prism) for simplicity. Experiments were conducted on different sizes of core samples with cylindrical shapes yielding the highest imbibition rates and triangular prisms the lowest imbibition rates. Characteristic length had an inverse effect on the rate of spontaneous imbibition within the same shape family of core samples. Boundary condition (BC) experiments were performed to investigate the effect of the boundary on the rate of spontaneous imbibition. The four different boundary conditions applied to the samples were (1) all faces open (AFO), (2) two ends closed (TEC), (3) two ends open (TEO), and (4) one end open (OEO) systems. BC experiments showed that an increase in total surface area open to imbibition promoted the rate of spontaneous imbibition. In this study, kerosene/brine/Berea systems showed that imbibition recovery rates increase with an increase in shape factor while decreasing in characteristic length specific to the same shape of core samples.     

Field Evaluation of a Leachate Collection System Constructed with Scrap Tires

Landfilling costs and the potential uses of scrap tires have prompted researchers to investigate beneficial reuses. One important application is the use of tire chips as a leachate collection material in municipal solid waste landfills. Laboratory and field studies were conducted to investigate the performance of tire chips as a drainage medium in landfills. The laboratory portion of the program included a series of hydraulic conductivity and compressibility tests. Two field test cells, one with tire chips and another with gravel as the control, were constructed. The tire-chip cell was instrumented with flowmeters, thermistors, and gas collection devices to evaluate the hydraulic performance as well as the potential for spontaneous combustion. Leachate collected from the two cells was analyzed to determine if tire chips would potentially contaminate the groundwater. The results indicated that adequate drainage conditions were present within the tire-chip layer. The presence of insignificant quantities of carbon monoxide, and the lack of oxygen, and recorded low temperatures suggested that a combustion hazard was not present. The field leachate data indicated that tire chips can be safely used as part of a landfill leachate collection layer, even though it may not be suitable to place them near drinking water sources.     

Suggestion of an Indicator to Evaluate Material Deposition in Resistance Spot Welding: Weld–Surface Interaction Index

Resistance spot welding (RSW) is still leading joining process in the automotive industry due to the simplicity and speed of the process. On the other hand, galvanized steel sheets provide improvement in corrosion resistance of the auto body. Material deposition has an influence on the corrosion resistance and weld strength; however, in the literature very little effort has been made to identify any weld–surface interaction numerically. In this study, a numerical approach called “Weld–Surface Interaction Index” (I_WSI) has been introduced to investigate the effect of material deposition on the corrosion sensitivity of the welding zone and its periphery. A systematic investigation was carried out to better understand the effects of an electrode cap–galvanized steel sheet interface on the corrosion resistance of spot-welded steel. The chemical composition of DP600 steel sheet and Z-Trode electrode cap was analyzed by using a spectrometer. The specimens were then joined by using same caps up to 1200 welds. SEM–EDS analysis was also performed on the chosen specimens to determine the weight percentages (wt.%) of Fe, Zn and Cu. EDS analysis results and coefficient of variation wt.% of Fe, Zn and Cu were used to compose I_WSI formula. In the proposed formula, wt.% of Zn represented resistivity of the cover to corrosion, while wt.% of Fe represents the vulnerability.     

Oxidation and thermal shock behavior of thermal barrier coated 18/10CrNi alloy with coating modifications

In this study, substrates of 18/10CrNi alloy plates were initially sprayed with a Ni-21Cr-10Al-1Y bond coat and then with an yttria stabilized zirconia top coat by plasma spraying. Subsequently, plasma-sprayed Thermal barrier coatings (TBCs) were treated with two different modification methods, namely, vacuum heat treatment and laser glazing. The effects of modifications on the oxidation and thermal shock behavior of the coatings were evaluated. The effect of coat thickness on the bond strength of the coats was also investigated. Results showed enhancement of the oxidation resistance and thermal shock resistance of TBCs following modifications. Although vacuum heat treatment and laser glazing exhibited comparable results as per oxidation resistance, the former generated the best improvement in the thermal shock resistance of the TBCs. Bond strength also decreased as coat thickness increased.     

A snapshot of renewable energy research in Turkey

The present study was conducted to find out the development trends of the scientific studies in the field of renewable energies in Turkey. All the publications in the ISI Web database were screened using 36 different keywords in title or topics based on the affiliation addresses including the word “Turkey”. A total of 12,197 publications were processed article by article and as a result 1555 papers were found to focus on renewable energies between the years 1980 and 2008 with the contributions of 1605 authors. The results showed that 45.2% was experimental, 34.3% informational studies whereas 20.5% was available system analysis. Number of publications in biomass and conversion system (39.1%) and solar energy systems (20.0%) were dominating. Both number of publications and citations increased in the last decade and more than half of total contributions were published last four years. Results indicated that policy development studies (3.3%) were the weakest among the whole parameters investigated.