The integration density of state-of-the-art electronic systems is limited by the reliability of the manufactured integrated circuits at a desired circuit density. Design rules, operating voltages, frequencies, and temperatures are precisely chosen to ensure correct product functional operation over its intended lifetime. Thus, in order to obtain the overall performance and functionality bounded by various design and manufacturing constraints, the integrated circuit reliability must be modeled and analyzed at the very beginning of design stages. This paper reviews some of the most important intrinsic wearout mechanisms of MOSFETs (including hot-carrier injection, time-dependent dielectric breakdown, and negative bias temperature instability) and introduces new accelerated-lifetime and SPICE compact models of these wearout mechanisms. Based on these circuit-aging models, a new SPICE reliability simulation approach is proposed and demonstrated with a simplified SRAM design on a commercial 90-nm technology to help designers understand device-failure behaviors, predict circuit reliability, and improve product robustness.

Energy storage is crucial for both smart grids and renewable energy sources such as wind or solar, which are intermittent in nature. Compared to electrochemical batteries, flywheel energy storage systems (ESSs) offer many unique benefits such as low environmental impact, high power quality, and larger life cycles. This paper presents a novel utility-scale flywheel ESS that features a shaftless, hubless flywheel. The unique shaftless design gives it the potential of doubled energy density and a compact form factor. Its energy and power capacities are 100 kWh and 100 kW, respectively. The flywheel is made of high-strength steel, which makes it much easier to manufacture, assemble, and recycle. Steels also cost much less than composite materials. Design and analysis of the shaftless flywheel are presented first. In addition, the system incorporates a new combination active magnetic bearing. Its working principle and levitation control for the flywheel are discussed. The design of an integrated coreless permanent-magnet (PM) motor/generator for the flywheel is given as well. Initial test results show that the magnetic bearing provides stable levitation for the 5443-kg flywheel with small current consumption.

Conventional active magnetic bearing (AMB) systems use several separate radial and thrust bearings to provide a five-degree of freedom (DOF) levitation control. This article presents a novel combination 5-DOF AMB (C5AMB) designed for a shaft-less, hub-less, high-strength steel energy storage flywheel (SHFES), which achieves doubled energy density compared to prior technologies. As a single device, the C5AMB provides radial, axial, and tilting levitations simultaneously. In addition, it utilizes low-cost and more available materials to replace silicon steels and laminations, which results in reduced costs and more convenient assemblies. Apart from the unique structure and the use of low magnetic grade material, other design challenges include shared flux paths, large dimensions, and relatively small air gaps. The finite-element method (FEM) is too computationally intensive for early-stage analysis. An equivalent magnetic circuit method (EMCM) is developed for modeling and analysis. Nonlinear FEM is then used for detailed simulations. Both permanent magnets (PMs) and electromagnetic control currents provide the weight-balancing lifting force. During the full-scale prototype testing, the C5AMB successfully levitates a 5440-kg and 2-m-diameter flywheel at an air gap of 1.14 mm. Its current and position stiffnesses are verified experimentally.

Capable of remote presentations of human heart activities, the Doppler cardiogram (DCG) can be detected by an agile Doppler radar sensor. However, as a recently developed technology, its performance needs sustained improvements for the future practical applications. In this work, a continuous-wave, ${V}$ -band Doppler radar sensor was implemented to improve the discrimination of the receiver, for detecting micrometer-level details of heartbeat motions conducted to the chest skin. Besides, new algorithms were derived to achieve high linearity, to demodulate the Doppler phases and retrieve the fine details of DCG waveforms. Experimental measurements to different subjects showed significantly enhanced robustness and accuracy. The obtained results imply a promising potential of DCGs in wide application scenarios such as medical wisdom and personal healthcare.

This paper proposes a framework for the design and analysis of a coreless permanent magnet (PM) machine for a 100 kWh shaft-less high strength steel flywheel energy storage system (SHFES). The PM motor/generator is designed to meet the required specs in terms of torque-speed and power-speed characteristics given by the application. The design challenges of a motor/generator for this architecture include: the poor flux paths due to a large scale solid carbon steel rotor and zero-thermal convection of the airgap due to operation of the machine in vacuum. Magnetic flux in this architecture tends to be 3-D rather than constrained due to lack of core in the stator. In order to tackle these challenges, several other parameters such as a proper number of magnets and slots combination, wire thickness, number of turns in each coil, magnets with high saturated flux density and magnets size are carefully considered in the proposed design framework. Magnetic levitation allows the use of a coreless stator that is placed on a supporting structure. The proposed PM motor/generator comprehensive geometry, electromagnetic and mechanical dimensioning are followed by detailed 3-D finite element analysis (FEA). The torque, power, and speed determined by the FEA electromagnetic analysis are met by the application design requirements and constraints for both the charging and discharging modes of operation. Furthermore, the design and analysis of the coil holding structures are discussed. Finally, the motor/generator static thermal analysis is discussed in order to validate the proposed cooling system functionality.