A new boundary element formulation for wave load analysis

A new boundary element (BEM) formulation is proposed for wave load analysis of submerged or floating bodies. The presented formulation, through establishing an impedance relation, permits the evaluation of the hydrodynamic coefficients (added mass and damping coefficients) and the coefficients of wave exciting forces systematically in terms of system matrices of BEM without solving any special problem, such as, unit velocity or unit excitation problem. It also eliminates the need for scattering analysis in the evaluation of wave exciting forces. The imaginary and real parts of impedance matrix give, respectively, added mass and damping matrices whose elements describe the fluid resistance against the motion of the body. The formulation is explained through the use of a simple fluid-solid system under wave excitations, which involves a uniform fluid layer containing a solid cylindrical body. In the formulation, the solid body is taken first as deformable, then, it is specialized when it is rigid. The validity of the proposed method is verified by comparing its result with those available in literature for rigid submerged or floating bodies.     

Photovoltaic properties of polymer based organic solar cells adapted for non-transparent substrates

This paper explains a semi-transparent photovoltaic device structure using polymer based materials for light harvesting. Poly(3-hexylthiophene-2,5-diyl):[6,6]-phenyl C₆₁ butyric acid methyl ester (P3HT:PCBM) and poly(2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylenevinylene) (MDMO-PPV:PCBM) as photoactive nano-layers were utilized and semi-transparent cells were compared with reference cells. Photoelectrical properties of developed devices were investigated. Also influencing factors of power conversion efficiency of devices were determined and possible application areas including solar harvesting textiles were discussed.     

Sulphur in Turkish lignites and possible remedies

Lignites are the largest and most important solid fuels of Turkey. The high sulphur content of these fuels, their low calorific value and high ash content pose problems in their use. The organic sulphur content is generally over 5% in Turkish lignites, which makes simple technologies, such as washing and flotation, unapplicable. Pyrolysis, wet chemical desulphurisation and biochemical desulphurisation technologies are either not capable of reducing the sulphur to desired limits, or uneconomical. Overall, the most promising technology in overcoming the sulphur problem in Turkish lignites seems to be fluidised bed combustion.     

Scheduling continuous aluminium casting lines

This study considers the problem of scheduling casting lines of an aluminium casting and processing plant. In aluminium processing plants, continuous casting lines are the bottleneck resources, i.e. factory throughput is limited by the amount of aluminium that can be cast. The throughput of a casting line might be increased by minimizing total setup time between jobs. The objective is to minimize setup time on production lines for a given time period while balancing workload between production lines to accommodate potential new orders. A mathematical formulation for scheduling jobs to minimize the total setup time while achieving workload balance between the production lines is presented. Since the casting scheduling problem is an NP-hard problem, even with only one casting line, a four-step algorithm to find good solutions in a reasonable amount of time is proposed. In this process, a set of asymmetric travelling salesman problems is followed by a pairwise exchange heuristic. The proposed procedure is applied to a case study using real casting data.     

Physical and chemical properties of tomato, green tea, and ginseng-supplemented corn extrudates produced by conventional extrusion and CO2 injection process

In this study, extrudates were produced from corn flour supplemented with tomato, green tea, and ginseng powder by conventional extrusion and CO₂ injection methods. In conventional extrusion process, the die exit temperatures were adjusted to 80, 110, 130 °C and CO₂ injection method was carried out at 80 °C. In both extrusion methods, the feed moisture, screw speed, and die diameter were kept constant at 20 %, 250 rpm, and 3 mm, respectively. Corn flour was supplemented with tomato powder at three different levels (4, 8, and 12 %), but ginseng and green tea were added only at 8 % level. The bulk density results generally had an inverse relationship with the expansion index values. Higher tomato powder supplementation levels resulted in higher total phenolic compound levels and antioxidant activities. These increases were around 11-fold as compared to control samples in 12 % tomato powder supplementation level at 130 °C extrusion temperature. The results indicated that antioxidant activity increased with increasing extrusion temperature. This increase might be due to higher amount of Maillard reaction products, with antioxidant activity, formed at higher extrusion temperatures. The color (L*, a*, b*) and hydroxymethylfurfural results proved that the rate of Maillard reaction increased at higher extrusion temperatures during the extrusion process. Green tea supplementation resulted in higher total phenolic compounds and antioxidant activity values as compared to tomato and ginseng supplementation under the same extrusion conditions.     

利用低门限电压延长电池寿命

降低能量消耗、延长电池寿命,这是每个工程师在设计便携式电子产品时努力的目标.电池技术的进步非常缓慢,所以便携式产品的设计者把延长电池寿命的重点放在电源管理上.     

Evaluation of radon concentration in well and tap waters in Bursa, Turkey

(222)Rn measurements in water samples collected from 27 wells and 19 taps that were supplied from the investigated wells were conducted using the AlphaGUARD PQ 2000PRO radon gas analyser at sites across several geologic formations within the city of Bursa, Turkey. The measured radon concentrations ranged from 1.46 to 53.64 Bq l(-1) for well water and from 0.91 to 12.58 Bq l(-1) for tap water. Of the 27 sites sampled, only 7 had radon levels above the safe limit of 11.1 Bq l(-1) recommended by the USEPA. In general, all determined concentrations were well below the 100 Bq l(-1) revised reference level proposed by the European Union. These values of radon concentrations in water samples are compared with those reported from other countries. Doses resulting from the consumption of these waters were calculated. The minimum and the maximum annual mean effective doses due to (222)Rn intake through water consumption were 0.02 μSv a(-1) and 1.11 μSv a(-1), respectively.     

On absolute summability factors of infinite series

In this paper a general theorem on |A,δ|_k-summability methods has been proved. This theorem includes, as a special case, a known result in [E. Savas, Factors for |A|_k Summability of infinite series, Comput. Math. Appl. 53 (2007) 1045–1049].     

Novel membranes based on poly(5‐(methacrylamido)tetrazole) and sulfonated polysulfone for proton exchange membrane fuel cells

Proton‐exchange membrane fuel cells (PEMFC)s are increasingly regarded as promising environmentally benign power sources. Heterocyclic molecules are commonly used in the proton conducting membranes as dopant or polymer side group due to their high proton transfer ability. In this study, 5‐(methacrylamido)tetrazole monomer, prepared by the reaction of methacryloyl chloride with 5‐aminotetrazole, was polymerized via conventional free radical mechanism to achieve poly(5‐(methacrylamido)tetrazole) homopolymer. Novel composite membranes, SPSU‐PMTetX, were successfully produced by incorporating sulfonated polysulfone (SPSU) into poly(5‐(methacrylamido)tetrazole) (PMTet). The sulfonation of polysulfone was performed with trimethylsilyl chlorosulfonate and high degree of sulfonation (140%) was obtained. The homopolymers and composite membranes have been characterized by NMR, FTIR, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). ¹H‐NMR and FTIR confirmed the sulfonation of PSU and the ionic interaction between sulfonic acid and poly(5‐(methacrylamido)tetrazole) units. TGA showed that the polymer electrolyte membranes are thermally stable up to ～190°C. Scanning electron microscopy analysis indicated the homogeneity of the membranes. This result was also supported by the appearance of a single T_g in the DSC curves of the blends. Water uptake and proton conductivity measurements were, as well, carried out. Methanol permeability measurements showed that the composite membranes have similar methanol permeability values with Nafion 112. The maximum proton conductivity of anhydrous SPSU‐PMTet0.5 at 150°C was determined as 2.2 × 10^?6 S cm^?1 while in humidified conditions at 20°C a value of 6 × 10^?3 S cm^?1 was found for SPSU‐PMTet2. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40107.