Adaptive modulation techniques combat fading by employing a suitable modulation mode depending on the instantaneous channel conditions for improving the Bit Error Rate (BER) performance or the average throughput. Based on a generic model of constant-power adaptive modulation, exact closed form expressions of the average BER and the average throughput are derived, when employing square Quadratur...

This study determines the mean and fluctuating pressures for flow through a rectangular shallow cavity (ratio between length depth = 2.43, 4.43, 6.14; ratio width 0.5, 1.0, 2.0) at Mach number of 0.64 in blowdown transonic wind tunnel. A amplitude modulation analysis is used post-processing pressure signals. The spectral (wavelet) shows intermittent behavior discrete Rossiter–Heller modes. corr...

A two-dimensional, single-phase, isothermal, multicomponent, transient model is built to investigate the transport phenomena in unitized regenerative fuel cells (URFCs) under the condition of switching from the fuel cell (FC) mode to the water electrolysis (WE) mode. The model is coupled with an electrochemical reaction. The proton exchange membrane (PEM) is selected as the solid electrolyte of...

The mode switching in Cepheids is studied using the methods of nonlinear theory stellar pulsation, depending on main sequence mass $$M_{0}$$ and abundance elements heavier than helium $$Z$$ . grid evolutionary hydrodynamic models core–helium burning represented by 30 sequences stars with initial masses $$5.7M_{\odot}\leq M_{0}\leq 7.2M_{\odot}$$ $$Z=0.014$$ , 0.018, 0.022. For considered values...

A novel amplifier configuration is described, in which a bandpass delta-sigma modulator is used to produce a two-level (digital) signal representing an analog radio frequency (RF) input. Subsequently, a switching-mode amplifier and bandpass filter are used to amplify the signal and remove unwanted spectral components. This configuration has the potential of achieving high efficiency (typical of...