Microwave Measurements Part I: Linear Measurements

An Overview of the most relevant issues concerning RF and microwave linear measurements is presented. Vector Network Analyzer foremost used instrumentation for this kind of measures is describe

Contraction and optimality properties of an adaptive Legendre-Galerkin method: the multi-dimensional case

We analyze the theoretical properties of an adaptive Legendre-Galerkin method in the multidimensional case. After the recent investigations for Fourier-Galerkin methods in a periodic box and for Legendre-Galerkin methods in the one dimensional setting, the present study represents a further step towards a mathematically rigorous understanding of adaptive spectral/$hp$ discretizations of elliptic boundary-value problems. The main contribution of the paper is a careful construction of a multidimensional Riesz basis in $H^1$, based on a quasi-orthonormalization procedure. This allows us to design an adaptive algorithm, to prove its convergence by a contraction argument, and to discuss its optimality properties (in the sense of non-linear approximation theory) in certain sparsity classes of Gevrey type

On the decay of the inverse of matrices that are sum of Kronecker products

Decay patterns of matrix inverses have recently attracted considerable interest, due to their relevance in numerical analysis, and in applications requiring matrix function approximations. In this paper we analyze the decay pattern of the inverse of banded matrices in the form $S=M \otimes I_n + I_n \otimes M$ where $M$ is tridiagonal, symmetric and positive definite, $I_n$ is the identity matrix, and $\otimes$ stands for the Kronecker product. It is well known that the inverses of banded matrices exhibit an exponential decay pattern away from the main diagonal. However, the entries in $S^{-1}$ show a non-monotonic decay, which is not caught by classical bounds. By using an alternative expression for $S^{-1}$, we derive computable upper bounds that closely capture the actual behavior of its entries. We also show that similar estimates can be obtained when $M$ has a larger bandwidth, or when the sum of Kronecker products involves two different matrices. Numerical experiments illustrating the new bounds are also reported

Gravitational waves emitted by extrasolar planetary systems

In this paper we consider the Extra-solar Planetary Systems recently discovered in our Galaxy as potential sources of gravitational waves. We estimate the frequency and characteristic amplitude of the radiation they emit due to the orbital motion, using the quadrupole formalism. In addition, we check whether the conditions needed for the resonant excitation of the f- and g-modes of the central star can be fulfilled. By a Roche-lobe analysis, we show that there could exist systems in which the low-order g-modes could be excited, although this does not happen in the systems discovered up to now.Comment: 14 pages, 5 figures. Accepted for publication on International Journal of Modern Physics D. Table 6 and minor typos correcte

Measuring coherence of quantum measurements

The superposition of quantum states lies at the heart of physics and has been recently found to serve as a versatile resource for quantum information protocols, defining the notion of quantum coherence. In this contribution, we report on the implementation of its complementary concept, coherence from quantum measurements. By devising an accessible criterion which holds true in any classical statistical theory, we demonstrate that noncommutative quantum measurements violate this constraint, rendering it possible to perform an operational assessment of the measurement-based quantum coherence. In particular, we verify that polarization measurements of a single photonic qubit, an essential carrier of one unit of quantum information, are already incompatible with classical, i.e., incoherent, models of a measurement apparatus. Thus, we realize a method that enables us to quantitatively certify which quantum measurements follow fundamentally different statistical laws than expected from classical theories and, at the same time, quantify their usefulness within the modern framework of resources for quantum information technology.Comment: close to published versio

Microwave Measurements. Part II - Nonlinear Measurements

This paper addresses the problems in microwave non-linear measurements. It discusses techniques to synthesize loads, the most used non-linear measurement techniques, and harmonic load-pulling. An experimental setup for characterizing power amplifiers must be able to measure the complex spectrum of the waves at the amplifier ports as a function of frequency, input power, and source and load termination at the fundamental and harmonic frequencies. The vector network analyzer (VNA) is the core instrument used in the non-linear characterization scenario. The basic idea is to keep the operations of VNA/mixers linear, diverting to them only a small portion of the signal present at the device under test (DUT) ports, therefore keeping unaltered the VNA capabilities already exhibited for small signal measurements

A Comprehensive Mixed-Mode Time-Domain Load- and Source-Pull Measurement System

We present a novel test set devised for nonlinear balanced device characterization using load-pull techniques. The system is capable of measuring the voltage and current waveforms at the calibration reference planes while independently tuning the device under test (DUT) source and load differential- and common-mode terminations. The test set is designed to address present and future large-signal multiport measurement needs, easing the characterization task while developing new multiport active device

Paying Attention to Cernuda and Bergamin Literary Surveillance during Francoism

El ensayo literario es un género que no se destina a un público amplio si lo comparamos con los dirigidos a lectores de novelas o de poemas. Sin embargo, parece que la censura franquista no consideraba dicha diferencia, ya que actuó con igual criterio inflexible en el análisis de los textos críticos. Este artículo examina libros de ensayos de Cernuda y de Bergamín para observar tal procedimiento de vigilancia literaria.A literary assay usually achieves a restrict number of readers if it is compared to a narrative text or poetical publication. Although this evidence, the censure service at Franco’s dictatorship seemed to consider the same rigorous and inflexible criteria to judge the literary critics. This paper analyzed the censure reports based on books written by Cernuda and Bergamín in order to demonstrate the use of identical procedures even to a restrict circulation work

Assessing frequency correlation through a distinguishability measurement

The simplicity of a question such as wondering if correlations characterize or not a certain system collides with the experimental difficulty of accessing such information. Here we present a low demanding experimental approach which refers to the use of a metrology scheme to obtain a conservative estimate of the strength of frequency correlations. Our testbed is the widespread case of a photon pair produced per downconversion. The theoretical architecture used to put the correlation degree on a quantitative ground is also described

A Framework to Use Public-Private Partnership for Smart City Projects

The concept of Smart City has been emerging as a strategic set of integrated initiatives encompassing infrastructures, technology and digital services for the purpose of enhancing the quality of life of citizens. However, the development and implementation of Smart City projects require considerable investments that are difficult to fund with traditional public finance. In this context, Public-Private-Partnerships (PPP) appear to be suitable solutions to overcome the shortage of public finance and cuts on public spending. However, the adoption of PPP forms for Smart City projects has not been fully explored and only experimentally applied so far. In order to promote the usage of PPP to finance Smart City initiatives, this paper proposes some PPP financial instruments and discusses the associated strengths and weaknesses. In particular, the use of Project Finance, Revenue Sharing and Social Impact Bonds are suggested as sound alternatives and suitable sources of financing for Smart City project