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The paper introduces and illustrates the use of numerical models for the simulation of electromagnetic and thermal processes in an absorbing ceramic layer (susceptor) of a new millimeter-wave (MMW) heat exchanger. The purpose of this study is to better understand interaction between the MMW field and the susceptor, choose the composition of the ceramic material and help design the physical prototype of the device.

A simplified version of the heat exchanger comprises a rectangular block of an aluminum nitride (AlN) doped with molybdenum (Mo) that is backed by a thin metal plate and irradiated by a plane MMW. The coupled electromagnetic-thermal problem is solved by the finite-difference time-domain (FDTD) technique implemented in QuickWave. The FDTD model is verified by solving the related electromagnetic problem by the finite element simulator COMSOL Multiphysics. The computation of dissipated power and temperature is based on experimental data on temperature-dependent dielectric constant, loss factor, specific heat and thermal conductivity of the AlN:Mo composite. The non-uniformity of patterns of dissipated power and temperature is quantified via standard-deviation-based metrics.

It is shown that with the power density of the plane wave on the block’s front face of 1.0 W/mm², at 95 GHz, 10 × 10 × 10-mm blocks with Mo = 0.25 – 4% can be heated up to 1,000 °C for 60-100 s depending on Mo content. The uniformity of the temperature field is exceptionally high – in the course of the heating, temperature is evenly distributed through the entire volume and, in particular, on the back surface of the block. The composite producing the highest level of total dissipated power is found to have Mo concentration of approximately 3%.

In the electromagnetic model, the heating of the AlN:Mo samples is characterized by the volumetric patterns of density of dissipated power for the dielectric constant and the loss factor corresponding to different temperatures of the process. The coupled model is run as an iterative procedure in which electromagnetic and thermal material parameters are upgraded in every cell after each heating time step; the process is then represented by a series of thermal patterns showing time evolution of the temperature field.

Determination of practical dimensions of the MMW heat exchanger and identification of material composition of the susceptor that make operations of the device energy efficient in the required temperature regime require and expensive experimentation. Measurement of heat distribution on the ceramic-metal interface is a practically challenging task. The reported model is meant to be a tool assisting in development of the concept and supporting system design of the new MMW heat exchanger.

While exploitation of a finite element model (e.g. in COMSOL Multiphysics environment) of the scenario in question would require excessive computational resources, the reported FDTD model shows operational capabilities of solving the coupled problem in the temperature range from 20°C to 1,000°C within a few hours on a Windows 10 workstation. The model is open for further development to serve in the ongoing support of the system design aiming to ease the related experimental studies.

The authors analyzed data and information mainly from the company’s annual reports and the books written by the CEO.

How and when can a “value” brand upscale its brand image? In the wake of the financial crisis of 2007–2008, UNIQLO – Japan’s street fashion brand – considered introducing a new brand collaboration. They needed to capture the attention of younger, more fashionable consumers. However, people were tightening their spending as they faced uncertainties related to their jobs and wealth. Even though UNIQLO had had a steady growth in sales for the previous 24 years, it was questionable whether it was strategically a good time to launch a premium brand collaboration. And if so, who was the right partner? High-end designer Jil Sander, fashionable New York-based Theory or emerging French “casual luxury” brand Comptoir des Cotonniers?

This case is about the challenges faced by a low-priced brand to collaborate with a high-end brand to enhance the brand image. It explores the important elements to take into consideration when evaluating launching collaboration using the high-end brand’s name. The students will learn how to examine the risks and benefits of creating a new image for the core brand. If the students had learnt branding or brand extension before, this case can be used to teach how consumer’s perception affects brand extension and the target market’s impact on pricing and distribution strategies. It can be used for a marketing course at the MBA level to explore the concepts in a growing company’s brand image or an undergraduate specialized course in brand management or marketing management. The students also learn how the fashion industry’s supply chain management works to adapt to rapidly changing fashion trends.