Performance Analysis of Maximum Likelihood Estimation for Multiple Transmitter Locations

The paper considers the consistence condition of Maximum Likelihood (ML) estimation for multiple transmitter locations in a wireless network with cooperative receiver nodes. It is found that the location set of receiver nodes should not locate (or asymptotically in some sense) merely in an algebraic curve of order 2M −1 if there are totally M transmitters. A sufficient condition for consistence of the ML estimation for M transmitters is that the limit set of locations contains a subset, comprised of (2M2 −M +2) points, which is non-C-2M-co-curved, a notion given by Definition IV-B. This condition can be compared to the persistent excitation condition used to guarantee the convergence of least squares algorithm. Numerical experiments are designed to demonstrate the theoretical discoveries in both positive and negative aspects.

Temporally modulated energy shuffling in highly interconnected nanosystems

Advances in lighting and quantum computing will require new degrees of control over the emission of photons, where localized defects and the quantum confinement of carriers can be utilized. In this contribution, recent developments in the controlled redistribution of energy in rare earth (RE)–doped nanosystems, such as quantum dots or within bulk insulating and semiconducting hosts, will be reviewed. In their trivalent form, RE ions are particularly useful dopants because they retain much of their atomic nature regardless of their environment; however, in systems such as GaN and Si, the electronic states of the RE ions couple strongly to those of the host material by forming nanocomplexes. This coupling facilities fast energy transfer (ET) (<100 ps) and a carrier-mediate energy exchange between the host and the various states of the RE ions, which is mediated by the presence of carriers. A model has been developed using a set of rate equations, which takes into consideration the various ET pathways and the lifetimes of each state within the nanocomplex, which can be used to predict the nature of the emitted photons given an excitation condition. This model will be used to elucidate recent experimental observations in Eu-doped GaN.

Motorized and Functional Electrical Stimulation Induced Cycling via Switched Adaptive Concurrent Learning Control

Cycling induced by functional electrical stimulation (FES) with motorized assistance is a rehabilitative approach for individuals with movement impairments. In this paper, an adaptive controller is designed for cadence tracking by switching across multiple muscle groups and an electric motor. The control design and analysis are based on a recently developed adaptive method called integral concurrent learning and an invariance-like tool to ensure stability of switched adaptive systems. A Lyapunov-based stability analysis for the overall switched rider-cycle system is segregated into two phases. During the first phase when sufficient learning has not been attained, which is quantified by a finite excitation condition, global asymptotic tracking and bounded parameter estimation are guaranteed. In the second phase, global exponential tracking and parameter convergence is ensured after the finite excitation condition is satisfied for all the subsystems within a finite time.