Magnetohydrodynamics around a cylindrical wire carrying electric currents

Journal of Mechanical Science and Technology - Vortex shedding phenomenon is closely linked with noise and vibration, many studies that consider the associated environmental or structural safety...     

Flexible Transparent Reduced Graphene Oxide Sensor Coupled with Organic Dye Molecules for Rapid Dual‐Mode Ammonia Gas Detection

Flexible chemical sensors utilizing chemically sensitive nanomaterials are of great interest for wearable sensing applications. However, obtaining high performance flexible chemical sensors with high sensitivity, fast response, transparency, stability, and workability at ambient conditions is still challenging. Herein, a newly designed flexible and transparent chemical sensor of reduced graphene oxide (R‐GO) coupled with organic dye molecules (bromophenol blue) is introduced. This device has promising properties such as high mechanical flexibility (>5000 bending cycles with a bending radius of 0.95 cm) and optical transparency (>60% in the visible region). Furthermore, stacking the water‐trapping dye layer on R‐GO enables a higher response as well as workability in a large relative humidity range (up to 80%), and dual‐mode detection capabilities of colorimetric and electrical sensing for NH₃ gas (5–40 ppm). These advantageous attributes of the flexible and transparent R‐GO sensor coupled with organic dye molecules provide great potential for real‐time monitoring of toxic gas/vapor in future practical chemical sensing at room conditions in wearable electronics.     

Development of a microbial time-temperature integrator system using lactic acid bacteria

A microbial time-temperature integrator (TTI) system was developed using lactic acid bacteria (Weissella koreensis) obtained from baechukimchi. Activation energy (Ea), which represents the temperature dependence of the TTI response, was calculated using the Arrhenius equation. Ea values for the color change (ΔE value), maximum specific growth rate (μ_max), and pH change of the TTI measured under different isothermal conditions (5, 10, 15 and 20°C) were 99.88, 95.91, and 93.38 kJ/mol, respectively. According to the time taken to reach the TTI endpoint by the initial inoculum level of W. koreensis (6.2, 5.5, 4.5, and 3.4 log CFU/mL), a negative correlation was observed in 63.5, 101.8, 115.1 and 166.6 h. In addition, initial bacterial counts decreased significantly up to almost 4% at 20°C in 3 months when W. koreensis viability was measured at the freezing point of the microbial TTI system (20 and ?80°C) for 1 week, 1 month, 2 months, and 3 months. However, viability was about 95% at 80°C. This microbial TTI system would be useful to monitor the quality of food with similar Ea values during storage or distribution.     

High‐performance and robust operation of anode‐supported solid oxide fuel cells in mixed‐gas atmosphere

We demonstrate the high‐performance and robust operation of anode‐supported solid oxide fuel cells under a mixed‐gas atmosphere applying a novel cell structure and characterization method, useful for minimizing the conventional problems of mixed‐gas operation with anode‐supported solid oxide fuel cells. To achieve the exothermic methane (CH₄) partial oxidation and sufficient difference in oxygen partial pressure even in mixed‐gas mode, a composite of metallic rhodium and cerium dioxide (CeO₂) was chosen as the optimized reforming and oxygen barrier layer after the comprehensive catalytic experiment. We also obtained increased cell operation reliability through the combination of anode pre‐reduction, an optimized material system, and a customized characterization jig (including cathode‐ahead layout and impinging jet flow). According to the cell test at 600°C under a feeding gas of CH₄ and O₂, an open‐circuit voltage and maximum power density of 0.916 V and 0.422 W/cm², respectively, were successfully achieved. Copyright © 2015 John Wiley & Sons, Ltd.     

Art‐photographic detail enhancement

We present a novel method for enhancing details in a digital photograph, inspired by the principle of art photography. In contrast to the previous methods that primarily rely on tone scaling, our technique provides a flexible tone transform model that consists of two operators: shifting and scaling. This model permits shifting of the tonal range in each image region to enable significant detail boosting regardless of the original tone. We optimize these shift and scale factors in our constrained optimization framework to achieve extreme detail enhancement across the image in a piecewise smooth fashion, as in art photography. The experimental results show that the proposed method brings out a significantly large amount of details even from an ordinary low‐dynamic range image.     

Interaction of a shock wave with a turbulent boundary layer on a heated surface

The interaction of a shock wave with a turbulent boundary layer has been studied. A stream has been diagnosed using non-invasive visualization (schlieren method). During the investigation the effect of surface heating on the length of boundary layer separation has been studied. It has been discovered that during surface heating the dependence of the length of separation on the temperature ratio is approximated using a linear law.     

A Novel Cogging Torque Reduction Method for Interior-Type Permanent-Magnet Motor

This paper presents a novel design method to reduce the cogging torque of interior-type permanent-magnet (PM) motor. In the design method, the optimal notches are put on the rotor pole face, which have an effect on the variation of PM shape or the residual flux density of PM. Through the space harmonic field analysis, the positions of notches are found, and the optimal shapes of notches are determined by using finite element method. The validity of the proposed method is confirmed by experiments.     

Improvement strategy for edge waviness in roll bending process of corrugated sheet metals

This paper focuses on the corrugated thin-walled sheet metal in the roll bending process. The main defect that appears in corrugated panels subjected to high amounts of bending deformation is a wavy edge. Edge defects are caused by excessive longitudinal stress and strain near the edge of the plate, and local edge buckling may occur when some critical value of the bending radius is exceeded. This paper proposes two different approaches to avoid a wavy edge for a formed panel: excessive stress on the edge region is restrained by controlling the length of the cross-sectional end of the corrugated panel while considering the stress distribution, and the bending radius in each forming step is determined by considering the strain limit at which the initial edge waviness occurs to avoid excessive compression at particular steps. The experimental and numerical results indicated that the two proposed design strategies can minimize wavy edges in the formed shape.     

In-vivo human brain molecular imaging with a brain-dedicated PET/MRI system

Advances in the new-generation of ultra-high-resolution, brain-dedicated positron emission tomography-magnetic resonance imaging (PET/MRI) systems have begun to provide many interesting insights into the molecular dynamics of the brain. First, the finely delineated structural information from ultra-high-field MRI can help us to identify accurate landmark structures, thereby making it easier to locate PET activation sites that are anatomically well-correlated with metabolic or ligand-specific organs in the neural structures in the brain. This synergistic potential of PET/MRI imaging is discussed in terms of neuroscience and neurological research from both translational and basic research perspectives. Experimental results from the hippocampus, thalamus, and brainstem obtained with ¹⁸F-fluorodeoxyglucose and ¹¹C-3-amino-4-(2-dimethylaminomethylphenylsulfanyl)benzonitrile are used to demonstrate the potential of this new brain PET/MRI system.