Stationary Fourier transform spectrometry is an interesting concept for building reliable field or embedded spectroradiometers, especially for the mid- and far- IR. Here, a very compact configuration of a cryogenic stationary Fourier transform IR (FTIR) spectrometer is investigated, where the interferometer is directly integrated in the focal plane array (FPA). We present a theoretical analysis...

This paper examines the sustainability of current account in 27 European Union countries over period 2005Q1-2020Q3. First, series which is considered as ratio to gross domestic product, was applied traditional unit root test ADF and nonlinear KSS. According test, stationary 9 according KSS 5 countries. Later, FADF FKSS tests based on Fourier were applied. results, found 10 for 3 FKSS. results a...

A propagation of pulse generated by an electric dipole is studied. A general formula for the electric field, which is uniformly valid for large distance and time, is presented. Fourier transform, stationary phase and simple contour integration methods are applied. 1. CURRENT PULSE AND FOURIER TRANSFORM Electric dipole is excited by a current I(t) = I0f(t) where f(t) is a pulse. The Fourier tran...

We forecast high resolution solar irradiance time series using an exponential smoothing state space (ESSS) model. To stationarize the irradiance data before applying linear time series models, we propose a novel Fourier trend model and compare the performance with other popular trend models using residual analysis and the Kwiatkowski-Phillips-Schmidt-Shin (KPSS) stationarity test. Using the opt...

We consider the 3D stationary Boltzmann equation in convex domains with diffuse-reflection boundary condition. rigorously derive steady incompressible Navier-Stokes-Fourier system and justify asymptotic convergence as Knudsen number $ {\varepsilon} shrinks to zero. The proof is based on an intricate analysis of layers geometric correction focuses technical difficulties caused by singularity col...

Vector-valued, asymptotically stationary stochastic processes on r-compact locally compact abelian groups are studied. For such processes, we introduce a stationary spectral measure and show that it is discrete if and only if the asymptotically stationary covariance function is almost periodic. Using an “almost periodic Fourier transform” we recover the discrete part of the spectral measure and...

We introduce a class of non-stationary processes, or signals, that are close to stationary and call them locally stationary. They arise in many applications in seismology, in speech analysis and elsewhere. We show that their local spectral characteristics can be obtained eeciently using an adaptive windowed Fourier transform. We illustrate with some examples from seismology the use of our metho...