On robust estimation of the location parameter

Since the beginning of the 20th century, researchers have been looking for an effective way to transfer power without wired connections, but the wireless power transfer technology started to attract extensive interest from the industry side only in 2007 when the first smartphone was released and a consumer electronics revolution was triggered. Currently, the modern technology of wireless power transfer already has a rich research and development history as well as outstanding advances in commercialization. This review is focused on the description of distinctive implementations of this technology inspired by the modern trends in electrodynamics. We compare the performances of the power transfer systems based on three kinds of resonators, i.e., metallic coil resonators, dielectric resonators, and cavity mode resonators. We argue that metamaterials and meta-atoms are powerful tools to improve the functionalities and to obtain novel properties of the systems. We review different approaches to enhance the fun...

Wireless power transfer inspired by the modern trends in electromagnetics

This paper discusses the use of magnetically coupled resonators for midrange wireless non-radiative power transfer (WNPT). A quasi-static (circuit) model is developed to establish key measures of performance and to aid in design. The use of directly fed, resonant shielded loops for WNPT is also proposed for the first time. Two experimental WNPT systems employing shielded loops are reported. A comprehensive experimental study is performed, and the performance of the WNPT systems shows close agreement with analytical predictions and developed circuit models. With a single-turn system of loop radius 10.7 cm, power transfer efficiency of 41.8% is achieved at a loop separation of 35 cm (3.3 loop radii). When the number of turns is increased to ten, a power transfer efficiency of 36.5% is achieved at a loop separation of 56 cm (5.3 loop radii). Measured magnetic field levels in the vicinity of the WNPT systems are shown to closely agree with analytical field values.

A Power Link Study of Wireless Non-Radiative Power Transfer Systems Using Resonant Shielded Loops

The problem of estimating the parameters of a Rayleigh-Rice mixture density is often encountered in image analysis (e.g., remote sensing and medical image processing). In this paper, we address this general problem in the framework of change detection (CD) in multitemporal and multispectral images. One widely used approach to CD in multispectral images is based on the change vector analysis. Here, the distribution of the magnitude of the difference image can be theoretically modeled by a Rayleigh-Rice mixture density. However, given the complexity of this model, in applications, a Gaussian-mixture approximation is often considered, which may affect the CD results. In this paper, we present a novel technique for parameter estimation of the Rayleigh-Rice density that is based on a specific definition of the expectation-maximization algorithm. The proposed technique, which is characterized by good theoretical properties, iteratively updates the parameters and does not depend on specific optimization routines. Several numerical experiments on synthetic data demonstrate the effectiveness of the method, which is general and can be applied to any image processing problem involving the Rayleigh-Rice mixture density. In the CD context, the Rayleigh-Rice model (which is theoretically derived) outperforms other empirical models. Experiments on real multitemporal and multispectral remote sensing images confirm the validity of the model by returning significantly higher CD accuracies than those obtained by using the state-of-the-art approaches.

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Rayleigh-Rice Mixture Parameter Estimation via EM Algorithm for Change Detection in Multispectral Images

Single-Molecule Imaging of a Fluorescent Unnatural Amino Acid Incorporated Into Nicotinic Receptors

Shielded loops are commonly used for magnetic-field emission and susceptibility experiments. The shield is demonstrated to play a role which changes from low to high frequencies. In the lower frequency range it operates as an electrostatic shield while at higher frequencies it carries the field-generating/sensing currents. The consequences are discussed for the probe equivalent circuit, terminal impedance and calibration, and the relevant formulas are given, along with the expressions defining the frequency limits. Experiments accurately confirm the shield's HF behavior.

The high-frequency behavior of the shield in the magnetic-field probes

The Rice probability density function has received considerable attention for its various important technical and scientific applications. One of the more attractive techniques for extracting the distribution parameters, and possibly the most frequently applied, relies on the maximization of the likelihood function for a given set of experimentally determined samples, and many applications are documented in the literature. This paper offers a mathematical analysis which demonstrates that, subject to conditions universally verified in physical systems, an absolute maximum exists, and it is the unique point internal to the domain of existence which zeroes the gradient of the likelihood function. In all previous results, the presence of additional maxima, which are possibly larger than the one that had numerically been found, could not be excluded. We can incidentally state that this paper demonstrates that all previous results based on numerically finding a maximum indeed corresponded to absolute maxima. The mathematical derivations offered here are also suggestive of actions capable of improving the insight into the maximum-likelihood technique and its numerical implementation.

The Absolute Maximum of the Likelihood Function of the Rice Distribution: Existence and Uniqueness

Radio frequency magnetic fields are measured using loop probes. Among the aspects of nonideal behavior, a dominant and elusive one is the unwanted response to common-mode excitation. Little attention has been given to this effect in literature and means for predicting its rejection in comparison to the (intentional) differential-mode response are not available. Formulas to describe the common-mode rejection are derived in this paper and the role of the physical quantities (mainly geometry and frequency) influencing this behavior is quantitatively discussed and made evident. Experiments and computations confirming the theoretical predictions are offered.

Analysis of the common-mode rejection in the measurement and generation of magnetic fields using loop probes

A proficiency test through interlaboratory comparison of radiated emission measurements was carried out in the period of time comprised between May 2012 and May 2013. Nineteen test houses took part in the exercise providing 91 measurement results in total. Measurements were performed in anechoic chambers and in the frequency range comprised between 200 and 3000 MHz. A traveling sample circulated among the laboratories, generating a reference electromagnetic field whose amplitude was a priori known (with uncertainty) but not revealed to the participants until the end of the comparison. Measurement results were provided by the participants in terms of best estimate and uncertainty. The aggregate measurement result is here compared with the a priori known value and its uncertainty. The performance of the laboratories, quantified in terms of two performance statistics selected from ISO 13528, is analyzed and discussed. The measurement uncertainty declared by the laboratories is compared with the dispersion of the measurement results. Aspects concerning the design and conduct of the comparison are also presented and discussed.

Design, Preparation, Conduct, and Result of a Proficiency Test of Radiated Emission Measurements

In this paper, a new procedure is presented for accurately measuring the difference in performance between sites for radiation tests (emission/susceptibility). Differences as low as 0.5 dB can be detected, and this high sensitivity is a consequence of the basic idea of having the entire transmission/reception (T/R) system itinerate through all the sites under investigation. This rules out the otherwise determinant contribution of the system-associated uncertainties (mainly from non-reproducibility of receiving antenna and receiver). The results of the survey, thus, reliably quantify the amount of disagreement that can be accounted for as being due to the site non-ideality alone. Attention was confined to: 1) short-range, fully anechoic rooms (3-m T/R distance) and 2) the lower frequency range (30 to 300 MHz). These assumptions identify a type of site that is in frequent use today and a frequency range where the measurement conditions are usually very critical. Application of this method to different sites or configurations other than those considered here is straightforward. A total of 14 different sites were investigated, and their level of disagreement is collectively described here, in terms of standard deviation of the sample, and individually, in terms of one-to-one deviation, namely, each site against each other (91 pairs). The one-to-one results exclude that the observed collective deviation was due to the presence of a minority of defective sites, and thus, demonstrating that the collective deviation that we derived effectively describes the amount of statistical disagreement in the whole sample. The measured sample standard deviation can be inserted in an overall uncertainty budget together with the independently derived instrumentation uncertainties. All aspects of the physical design of the experiment are analyzed to demonstrate the steps needed to obtain the high sensitivity that is required here.

Carlo Carobbi

Papers

The high-frequency behavior of the shield in the magnetic-field probes

The Absolute Maximum of the Likelihood Function of the Rice Distribution: Existence and Uniqueness

Analysis of the common-mode rejection in the measurement and generation of magnetic fields using loop probes

Design, Preparation, Conduct, and Result of a Proficiency Test of Radiated Emission Measurements

Reproducibility of Radiated Emissions Measurements in Compact, Fully Anechoic, Rooms—The Contribution of the Site-to-Site Variations