analysis of time series data can involve the inversion of large covariance matrices. for theclass of arma (p, q) processes there are no exact explicit expressions for these inverses, except for thema (1) process. in practice, the sample covariance matrix can be very large and inversion can becomputationally time consuming and so approximate explicit expressions for the inverse are desirable.thi...

The objective of this paper is to study the M/M/R machine repair queueing system with mixed standbys. The life-time and repair time of units are assumed to be exponentially distributed. Failed units are repaired on FCFS basis. The standbys have switching failure probability q (0≤q≤1). The repair facility of the system consists of R permanent as well as r additional removable repairmen. Due to i...

Abstract Resonant nanostructures, such as photonic metasurfaces, have created an unprecedented case for enhanced light–matter interactions through local field engineering. However, the presence of resonances fundamentally limits bandwidth interactions. Here, we report on amending nonlinear optical response a semiconducting metasurface Q-boosting, where Q-factor rapidly increases with time. The ...

Abstract Motivated by the exciting features and a recent proposed general form of function non-metricity scalar Q, we investigate cosmological implications in f ( Q ) gravity, through resulting effective dark energy sector, extracting analytical expressions for density, equation-of-state deceleration parameters. We show that even absence constant, universe exhibits usual thermal history, with s...