Exergoeconomic analysis of a vehicular PEM fuel cell system

In this study, we deal with the exergoeconomic analysis of a proton exchange membrane (PEM) fuel cell power system for transportation applications. The PEM fuel cell performance model, that is the polarization curve, is previously developed by one of the authors by using the some derived and developed equations in literature. The exergoeconomic analysis includes the PEM fuel cell stack and system components as compressor, humidifiers, pressure regulator and the cooling system. A parametric study is also conducted to investigate the system performance and cost behaviour of the components, depending on the operating temperature, operating pressure, membrane thickness, anode stoichiometry and cathode stoichiometry. For the system performance, energy and exergy efficiencies and power output are investigated in detail. It is found that with an increase of temperature and pressure and a decrease of membrane thickness the system efficiency increases which leads to a decrease in the overall production cost. The minimization of the production costs is very crucial in commercialization of the fuel cells in transportation sector.     

Selecting the suitable material handling equipment in the presence of vagueness

Selection of the suitable material handling equipment (MHE) is a very difficult task for the manufacturing companies because of the considerable capital investment required. There are many tangible and intangible factors for choosing the suitable MHE. Multiple criteria decision making (MCDM) has been found to be a useful approach to analyze these conflicting factors. The evaluation of MHE alternatives within the frame of various subjective criteria and the weights of the criteria are usually expressed in linguistic terms. This makes fuzzy logic a more natural approach to this kind of problems. This paper proposes a combined MCDM methodology for evaluation and selection of MHE types for a company in the steel construction industry in Istanbul, Turkey. Fuzzy analytic network process (FANP) is utilized for assigning weights of the criteria for MHE selection and fuzzy technique for order preference by similarity to ideal solution (TOPSIS) is used to determine the most proper system alternative using the criteria weights attained by FANP. The selection is based on the compatibility between MHE and production characteristics. Objective is to select the most efficient MHE considering also the cost efficiency. The study was followed by the sensitivity analyses of the results.     

Consistency Clustering: A Robust Algorithm for Group-wise Registration,Segmentation and Automatic Atlas Construction in Diffusion MRI

We propose an integrated registration and clustering algorithm, called “consistency clustering”, that automatically constructs a probabilistic white-matter atlas from a set of multi-subject diffusion weighted MR images. We formulate the atlas creation as a maximum likelihood problem which the proposed method solves using a generalized Expectation Maximization (EM) framework. Additionally, the algorithm employs an outlier rejection and denoising strategy to produce sharp probabilistic maps of certain bundles of interest. We test this algorithm on synthetic and real data, and evaluate its stability against initialization. We demonstrate labeling a novel subject using the resulting spatial atlas and evaluate the accuracy of this labeling. Consistency clustering is a viable tool for completely automatic white-matter atlas construction for sub-populations and the resulting atlas is potentially useful for making diffusion measurements in a common coordinate system to identify pathology related changes or developmental trends.     

On the Some Particularities of the Torsional Wave Dispersion in a Finitely Pre-Deformed Hollow Sandwich Cylinder

This paper develops the investigations started in a work by Akbarov, Kepceler and Mert Egilmez (2011) and studies the some particularities of the torsional wave dispersion in a finitely pre-deformed sandwich hollow cylinder. The mentioned particularities relate to the influence of the stiffness ratio of the core and face layers' materials and the influence of the thickness ratio of these layers on the dispersion character of the wave under consideration. Moreover, the mentioned influences are studied for the various values of the parameter which characterizes the initial strains in the cylinder's layers. The mechanical relations of the materials of the cylinders are described through the harmonic potential. The analytical expression is presented for the low wave number limit values of the torsional wave propagation velocity. The numerical results on the foregoing influences are presented and discussed.     

Identification of major ADH genes in ethanol metabolism of Pichia pastoris

The methylotrophic yeast Pichia pastoris (syn. Komagataella phaffii) is a successful host widely used in recombinant protein production. The widespread use of a methanol-regulated alcohol oxidase 1 (AOX1) promoter for recombinant protein production has directed studies particularly about methanol metabolism in this yeast. Although there is comprehensive knowledge about methanol metabolism, there are other mechanisms in P. pastoris that have not been investigated yet, such as ethanol metabolism. The gene responsible for the consumption of ethanol ADH2 (XM_002491337, known as ADH3) was identified and characterized in our previous study. In this study, the ADH genes (XM_002489969, XM_002491163, XM_002493969) in P. pastoris genome were investigated to determine their roles in ethanol production by gene disruption analysis. We report that the ADH900 (XM_002491163) is the main gene responsible for ethanol production in P. pastoris. The ADH2 gene, previously identified as the only gene responsible for ethanol consumption, also plays a minor role in ethanol production in the absence of the ADH900 gene. The investigation of the carbon source regulation mechanism has also revealed that the ADH2 gene exhibit similar expression behaviours with ADH900 on glucose, glycerol, and methanol, however, it is strongly induced by ethanol.     

Biogenic Amine Content of Beers Consumed in Turkey and Influence of Storage Conditions on Biogenic Amine Formation

The biogenic amine content of beers available in Turkey, both domestic production and imported products, was investigated. A total of 17 domestic and 13 imported beers were evaluated in terms of 8 different biogenic amines (histamine, tyramine, spermine, spermidine, 2‐phenylethylamine, putrescine, tryptamine and cadaverine). HPLC methodology with pre‐column derivatization and photodiode array detection after derivatization with dansyl chloride was used for quantification. In addition, the evolution of important amines such as histamine, tyramine, putrescine and cadaverine were investigated during different storage conditions by response surface methodology. The results indicated that both storage temperature and storage time were important factors affecting biogenic amine content. Histamine and putrescine increased during storage, but then decreased after reaching a maximum level after six weeks. With the biogenic amines tyramine and cadaverine, the amounts increased during the entire storage period. At higher storage temperatures, the formation of biogenic amines increased.     

Preparation and characterization of light curable hybrid coating: Its potential application for dental restorative material

The objective of this study was to synthesize a dual-functional light curable resin by the reaction between acrylated cycloaliphatic epoxy resin and 3-isocyanatopropyltrimethoxysilane and investigate the performance of this oligomer in the preparation of resin-based composite restoratives. FT-IR and ²⁹Si-NMR were used to characterize the structure of the hybrids. The char yields of the hybrids increased with inorganic content comes from TEOS (tetraethylorthosilicate) and synthesized SiUA oligomers. Gel content of polymeric films was found to be between 95% and 98%. Swelling was found to be between 3.1% and 3.8%. Weight loss of coated human teeth in synthetic saliva solution was found to be among 1% and 2%. There was a systematic increase in the modulus and tensile strength with the increase of inorganic content. On the other hand, elongation at break did not changed. Prepared hybrid coating materials exhibited improvement in tensile properties and hardness, when photo chemically cured.     

Strategies for ideal indoor environments towards low/zero carbon buildings through a biomimetic approach

Biomimicry is a relatively new discipline of applied science that seeks inspiration from natural systems for innovative solutions to human problems. Taking nature as ‘model, mentor and measure’ receives wide acceptance in the field of architecture but predominantly in conceptualising novel forms. The biomimicry concept is comprehensively analysed for its ability to provide more sustainable and possibly even regenerative built environments. As part of this study, first, various frameworks for approaching ‘biomimicry’ in general are discussed and then relevant examples pertaining to architecture are evaluated. Case studies are critiqued with respect to varied levels of sustainability achieved and its causative factors. In the second part, an approach model for ‘biomimetic architecture’ in the context of Mumbai is presented and applicable strategies based on climatic adaptation are suggested using local biodiversity as a library of organisms. The generic example of ‘human skin’ addressing the same adaptation is analysed and complemented by a state-of-the-art case study on similar lines. The results achieved clearly reveal that biomimicry is a successful approach to design and operate the sustainable built environments for the buildings of the future.     

Heat transfer enhancement in cylindrical fins through longitudinal parabolic perforations

In our previous works, it is clearly addressed that optimisation of fin profile is of vital importance in terms of the rate of heat transfer from a hot surface, and the optimisation procedure depends on several factors. Within the scope of this research, a longitudinal cylindrical fin profile is under interest for the optimisation research. The purpose is to investigate the effects of longitudinal parabolic perforations on the fin parameters such as temperature distribution, effectiveness and efficiency, in which the fin surface is cooled by natural convection and radiation. Different concavity levels are considered to form parabolic perforations. The rate of heat transfer from fin surface is numerically correlated with the fin mass with respect to different concavity levels. According to results, heat transfer from unit fin mass is enhanced with the new designs. The outcome of the study can be used to optimise the needs for particular applications by making a decision between heat loss and weight options. That is, the increase in the concavity level of the perforation results in a lighter and cheaper design, but yielding a lower heat loss. However, heat transfer from unit mass is still enhanced.