Estimation of the Intrinsic Power Efficiency in Magnetoelectric Laminates Using Temperature Measurements

Magnetoelectric (ME) power efficiency is a more important property than the ME voltage or the current coefficients for power conversion applications. This paper introduces an analytical model that describes the relation between the external magnetic field and the power efficiency in layered ME composites. It is a two-phase model. The first fragment establishes the expression between the magnetic field strength and the temperature increase within an operating period. It uses a magneto-elasto-electric equivalent circuit model that was developed by Dong et al. Following previous investigations; the main loss source is the mechanical power dissipation. The second fragment links the power efficiency and the temperature increase in a heat-balanced system. This method is generally used by researchers in the piezoelectric field. The analytical model and the experimental data shows that the decrease of the power efficiency in a laminated composite is between 5% and 10% for a power density of 10 W/in3 (0.61 W/cm3) to 30 W/in3 (1.83 W/cm3). The failure mechanism/process of ME composites under high power density can be estimated/monitored by the proposed method for ME composites in practical applications.

Study of Electrical Properties of Bistable Smectic-A Liquid Crystal Displays

Bistable smectic-A (SmA) liquid crystal display (LCD) is one of the most promising devices for smart glass applications due to long-term bistability, low haze at clear state, low transmittance at scatter state and low power consumption. The need of a good simulation model for an LCD becomes apparent during the design of driving system. Liquid crystal (LC) capacitance is critical in the simulation of LCD pixels and is voltage dependent due to the crystal characteristics. Bistable smectic-A LC capacitance model is introduced in the paper. The study describes the most relevant conclusions obtained from the measurements of electric properties of bistable SmA LCD samples and electric equivalent circuit characterization.