Physics‐based model of lithium‐ion batteries running on a circuit simulator

The authors developed a physics‐based equivalent circuit model of a lithium‐ion battery (LIB) whose parameters are continually updated, reflecting the theoretical calculation results of the Butler‐Volmer equation, diffusion equations of the lithium‐ion and lithium, and Nernst equations of the liquid and solid phases. The developed model was applied to the charge/discharge simulations of an LIB, and the experimental and simulated results of constant current discharges and pulsed‐charge/discharge were found to be in excellent agreement. In particular, using the developed model, analyzing transient responses of the LIB derived from the transition of the electric double layer charging to the electrode reaction is possible. These results demonstrate that the electrochemical performance of an LIB can be calculated on a circuit simulator using the developed model.     

Editorial for the 30th anniversary special issue

Applied Intelligence -     

Diffusion Magnetic Resonance Imaging-Based Biomarkers for Neurodegenerative Diseases

There has been an increasing prevalence of neurodegenerative diseases with the rapid increase in aging societies worldwide. Biomarkers that can be used to detect pathological changes before the development of severe neuronal loss and consequently facilitate early intervention with disease-modifying therapeutic modalities are therefore urgently needed. Diffusion magnetic resonance imaging (MRI) is a promising tool that can be used to infer microstructural characteristics of the brain, such as microstructural integrity and complexity, as well as axonal density, order, and myelination, through the utilization of water molecules that are diffused within the tissue, with displacement at the micron scale. Diffusion tensor imaging is the most commonly used diffusion MRI technique to assess the pathophysiology of neurodegenerative diseases. However, diffusion tensor imaging has several limitations, and new technologies, including neurite orientation dispersion and density imaging, diffusion kurtosis imaging, and free-water imaging, have been recently developed as approaches to overcome these constraints. This review provides an overview of these technologies and their potential as biomarkers for the early diagnosis and disease progression of major neurodegenerative diseases.     

A Study of Mutual Coupling between Vertical Grounding Electrodes

This paper investigates the mutual grounding impedance between vertical grounding electrodes based on field measurements and FDTD simulations. In the case of vertical electrodes, the mutual impedance between the electrodes is almost completely independent of the electrode length, and thus the induced voltage is nearly constant as the electrode length becomes longer. This characteristic is different from that of an overhead conductor, where the electromagnetic‐induced voltage is proportional to the conductor length. The greater the separation distance between the electrodes, the smaller the induced voltage, as in the case of an overhead conductor. The propagation speed increases as the separation increases. It is found that the speed is not necessarily proportional to the inverse of the relative permittivity of the earth.     

A consistent grayscale‐free topology optimization method using the level‐set method and zero‐level boundary tracking mesh

This paper proposes a level‐set based topology optimization method incorporating a boundary tracking mesh generating method and nonlinear programming. Because the boundary tracking mesh is always conformed to the structural boundary, good approximation to the boundary is maintained during optimization; therefore, structural design problems are solved completely without grayscale material. Previously, we introduced the boundary tracking mesh generating method into level‐set based topology optimization and updated the design variables by solving the level‐set equation. In order to adapt our previous method to general structural optimization frameworks, the incorporation of the method with nonlinear programming is investigated in this paper. To successfully incorporate nonlinear programming, the optimization problem is regularized using a double‐well potential. Furthermore, the sensitivities with respect to the design variables are strictly derived to maintain consistency in mathematical programming. We expect the investigation to open up a new class of grayscale‐free topology optimization. The usefulness of the proposed method is demonstrated using several numerical examples targeting two‐dimensional compliant mechanism and metallic waveguide design problems. Copyright © 2014 John Wiley & Sons, Ltd.     

Glass-Ceramics and Solid-State Lighting

Yttrium aluminum garnet (YAG) doped with Ce³⁺ ion is known as an excellent phosphor for light-emitting diode (LED), usually used as a powder form dispersed in organic resins. We have developed translucent glass-ceramics (GC) of YAG: Ce³⁺ microcrystals in 2004. The GC sheet with half millimeter thick can work efficiently to make identical emission spectra with conventional white LED when combined with a blue LED. This report reviews the development history of the GC materials and impact for all inorganic solution for solid-state lighting.     

Morphology‐dependent electrocatalytic activity of nanostructured Pt/C particles from hybrid aerosol–colloid process

An optimum nanostructure and pore size of catalyst supports is very important in achieving high catalytic performances. In this instance, we evaluated the effects of various carbon nanostructures on the catalytic performances of carbon‐supported platinum (Pt/C) electrocatalysts experimentally and numerically. The Pt/C catalysts were prepared using a hybrid method involving the preparation of dense, hollow, and porous nanostructured carbon particle via aerosol spray pyrolysis followed by microwave‐assisted Pt deposition. Electrochemical characterization of the catalysts showed that the porous Pt/C catalyst gave the best performance; its electrochemical surface area was much higher, more than twice than those of hollow or dense Pt/C. The effects of pore size on electrocatalysis were also studied. The results showed the importance of a balance between mesopores and macropores for effective catalysis with a high charge transfer rate. A fluid flow model showed that good oxygen transport contributed to the catalytic activity. © 2015 American Institute of Chemical Engineers AIChE J, 62: 440–450, 2016     

Measurement of the flood discharge of a small-sized river using an existing digital video recording system

In this study, a closed-circuit television (CCTV) system, installed for surveillance purposes, is utilized to measure the flow rate during a flood. The procedure to determine both the angle and scale-factor of the camera is described. Then, image analysis techniques, namely the direct visual measurement method, Large-Scale PIV (LSPIV) and Space-Time Image Velocimetry (STIV), are applied to the video images recorded by the CCTV camera. The results of these methods and the conventional float measurement are compared. In addition, the accuracy of the respective methods is discussed. A set of low-quality video images of a flood during a thunderstorm that occurred under the dark ambient conditions (midnight) is analyzed using three image-based methods. The transition of the flow rate during the event is successfully estimated.