CHARACTERIZATION OF CERIUM OXIDE AND CARBON SUPPORTED Ag-Cu ELECTRO-CATALYSTS FOR ANODE ELECTRODE IN DIRECT ETHANOL FUEL CELLS

In this study, electrochemical and spectroscopic characterization of home-made CeO₂, activated carbon-based Ag-Cu electro-catalysts, and preliminary anode polarization results in a direct ethanol fuel cell test system were presented. Ag-Cu transition metal couples were impregnated onto carbon and cerium oxide supports by wet impregnation, ion exchange, and co-precipitation techniques. Wet impregnation technique was selected for further spectroscopic analysis and fuel cell testing due to its easy metal loading advantage and highest peak currents in ethanol-containing electrolyte environment. When Ag and Cu were loaded 37.5 and 12.5 wt.% onto carbon and cerium oxide by wet impregnation technique, XPS analysis indicated an appreciable amount of Ag and Ag₂O and a high amount of CuO. In cerium oxide-based samples atomic percentage of oxygen fits well with the stoichiometry of CuO/CeO₂. Preliminary results show that BET surface area and the current peaks exhibit a close resemblance (highest BET surface area indicates highest anodic dissolution current), which is thought to be due to the high accessibility of copper layers impregnated onto cerium oxide and activated carbon in H₂SO₄ electrolyte environment. Hydrogen reduction of CeO₂-based samples prepared by wet impregnation at 750°C greatly improved anode polarization and onset oxidation potential.     

Deterioration Assessment and Rehabilitation Design of Existing Steel Bridge

Diagnostic truck-load tests and microstructural analysis were applied for structural deterioration assessment of a steel truss bridge and its rehabilitation design. The feasibility and potential benefits of using advanced field experimental techniques within a structural-identification framework have been demonstrated. Experimental information, coupled with visual inspection, engineering experience, and intuition, increased the level of confidence in the results of the condition-assessment process, permitting a more rational and cost-effective rehabilitation design. Based on the condition assessment, a two-step rehabilitation is recommended for the bridge: Restoration for a safe service life of 5–7 years, and a subsequent effort for preservation beyond.     

Double Carbonylation Reactions of Enynols and Thiols to Form Thioester Substituted 6‐Membered Ring Lactones

The double carbonylation reaction of enynols with thiols affords functionalized 6‐membered ring lactones. Two kinds of 6‐membered ring lactones were obtained by the use of different palladium complexes with added phosphine ligands.     

Rhodium Complexed C2‐PAMAM Dendrimers Supported on Large Pore Davisil Silica as Catalysts for the Hydroformylation of Olefins

Polyamidoamine (PAMAM) dendrimers up to the third generation were grown for the first time on the surface of a large‐pore (18 nm) Davisil silica support. The supported dendrimers of generations 0, 1, 2 and 3 were phosphinomethylated and complexed with rhodium. All the generations were found to be very active for the hydroformylation of olefins. The hydroformylation of 1‐octene was accomplished with a turnover frequency of 1700 h⁻¹ at 70 °C. The G(1) material was found to be the most active when the different generations were compared at 50% conversion at 70 °C     

A simulated annealing algorithm based approach for balancing and sequencing of mixed-model U-lines

It is known that two interrelated problems called as line balancing and model sequencing should be solved simultaneously for an efficient implementation of a mixed-model U-shape assembly line in a JIT (Just in Time) environment. On the other hand, three versions of assembly line balancing problem can be identified: Type I, Type II, and Type E. There are only two articles ( Kara, Ozcan, & Peker, 2007a and Hamzadayi & Yildiz, 2012) related to simultaneous balancing and sequencing of mixed-model U-lines for minimizing the number of stations (Type 1 problem) by ignoring the fixed model sequence in the current literature. In this paper, a simulated annealing algorithm is proposed for solving a problem of type 1 by ignoring the fixed model sequence. Accordingly, simulated annealing based fitness evaluation approach proposed by Hamzadayi and Yildiz (2012) is enhanced by adding the tabu list, and inserted into the proposed algorithm. Implementation difficulties experienced in meta-heuristics based on solution modification for solving these types of problems are demonstrated. ‘Absolute deviation of workloads’ (ADW) is quite frequently used as performance criteria in the literature. It is found that ADW is an insufficient performance criterion for evaluating the performance of the solutions, and this is showed by means of an illustrative example. The parameters of the proposed algorithm are reviewed for calibrating the algorithm by means of Taguchi design of experiments. Performance of the proposed approach is tested through a set of test problems. The results of computational experiments indicate that the proposed approach is an effective method in solving simultaneous line balancing/model sequencing problems for mixed-model U-lines for minimizing the number of stations.     

Simultaneous removal of C, N, P from cheese whey by jet loop membrane bioreactor (JLMBR)

The membrane bioreactor (MBR) used in this study consisted of a jet loop bioreactor (aerobic high rate system) and a membrane separation unit (microfiltration). Jet loop membrane bioreactor (JLMBR) system is a high performance treatment system. High organic loading rates can be achieved with a very small footprint. The JLMBR is a compact biological treatment system which requires much smaller tank volumes than conventional activated sludge system. Solid-liquid separation is performed with a membrane. The JLMBR system, of 35 L capacity, was operated continuously for 3 months with a sludge age of 1.1-2.8 days and chemical oxygen demand (COD) loads of 3.5-33.5 kg COD m(-3) day(-1). The mean concentration values of COD, total nitrogen (TN) and PO(4)3- in cheese whey (CW) were found as 78,680 mg L(-1), 1125 mg L(-1) and 378 mg L(-1), respectively. Ninety-seven percent COD removal rate was obtained at the sludge age (Thetac) of 1.6 days and volumetric loads of 22.2 kg COD m(-3) day(-1). TN removal was obtained as 99% at the loading rates of 17-436 g TN m(-3) day(-1). PO4(3-) removals were between 65 and 88% for the loading of 30-134 gPO4(3-) m(-3) day(-1). The system could simultaneously remove the COD, TN and PO(4)3- at high efficiencies. The sludge flocks were highly motile, dispersed and had poor settling properties.     

Primary Level Hydrophone Calibration System Based on PC Oscilloscope

Primary level “hydrophone calibration system” for calibrating hydrophones in the frequency range from a few to hundreds kilohertz under free-field conditions is presented. “Open architecture system” has been developed on the basis of conventional laboratory equipment, namely, signal generator, power amplifier, and digital PC-oscilloscope. Concept of design, measurement flowchart and results of validation with uncertainty budget of measurements are presented. The system covers wide frequency range of underwater applications and also presents low-cost solution enabling to reach sufficient level required for primary calibration according to standards.     

Evaluating the efficiency of local municipalities in providing traffic safety using the Data Envelopment Analysis

The purpose of this study was to estimate the relative efficiency of 197 local municipalities in traffic safety in Israel during 2004–2009, using Data Envelopment Analysis (DEA). DEA efficiency is based on multiple inputs and multiple outputs, when their weights are unknown. We used here inputs reflecting the resources allocated to the local municipalities (such as funding), outputs include measures that reflect reductions in accidents (such as accidents per population), and intermediate variables known as safety performance indicators (SPI): measures that are theoretically linked to crash and injury reductions (such as use of safety belts). Some of the outputs are undesirable. Using DEA, the local municipalities were rank-scaled from the most efficient to the least efficient and required improvements for inefficient municipalities were calculated. We found that most of the improvements were required in two intermediate variables related to citations for traffic violations. Several DEA versions were used including a two-stage model where in the first stage the intermediate variables are the outputs, and in the second stage they are the inputs. Further analyses utilizing multiple regressions were performed to verify the effect of various demographic parameters on the efficiency of the municipalities. The demographic parameters tested for each local municipality were related to the size, age, and socio-economic level of the population. The most significant environmental variable affecting the efficiency of local municipalities in preventing road accidents is the population size of the local authority; the size has a negative effect on the efficiency. As far as we could determine, this is the first time that the DEA is used to measure the efficiency of local municipalities in improving traffic safety.     

Semiempirical thermodynamic modeling of a direct methanol fuel cell system

In this study, a thermodynamic model of an active direct methanol fuel cell (DMFC) system, which couples in‐house experimental data for the DMFC with the mass and energy balances for the system components (condenser, mixing vessel, blower, and pumps), is formed. The modeling equations are solved using the Engineering Equation Solver (EES) program. This model gives the mass fluxes and thermodynamic properties of fluids for each state, heat and work transfer between the components and their surroundings, and electrical efficiency of the system. The effect of the methanol concentration (between 0.5 and 1.25 M) and air flow rate (between 20 and 30 mL cm^?2 min^?1) on the net power output and electrical efficiency of the system and the condenser outlet temperature is investigated. The results essentially showed that the highest value for the electrical efficiency of the system is 23.6% when the current density, methanol concentration, and air flow rate are taken as 0.2 A cm^?2, 0.75 M, and 20 mL cm^?2 min^?1, respectively. In addition, the air flow rate was found to be the most significant parameter affecting the condenser outlet temperature.     

A quality assessment of public water fountains and relation to human health: a case study from Yozgat,Turkey

Public fountains are very common and everyday people appreciate the benefits a water fountain can bring. However, consumption of public fountain water in some country has decreased because of growing concerns that constituents in fountain water may have adverse effects on health. A few studies have examined the safety of public fountains, proposing only limited evidence of fountain‐related health issues in Turkey. Most of these public fountains are sourced from natural springs in Turkey. In this study, a 177 fountain water and 32 rock samples were analysed for source and quality of water. The geology of the region has the direct impact on the quality of the public fountain water. The results indicate that the level of some elements exceeded the limit values determined by WHO and US.EPA. The most striking high values were observed for iron (Fe), nickel (Ni), aluminum (Al), arsenic (As) and bromine (Br) concentrations.