Frequency stability is one of the most important features of power systems. It is closely dependent on the value of system frequency. In the present day modern power systems, fast and accurate frequency estimation has become quite vital. Anymistake in accurate estimation of frequency may threaten the frequency stability or at least lead to system operation problems. In this paper, a new time-do...

the focus of this paper is to evaluate the influence of mechanical characteristics of the implant on primary stability in different bone types, based on resonance frequency analysis (rfa).a number of 60 nobel biocare replace select tiunit tapered implants of two different lengths (10 mm and 13 mm) and three different widths as 3.4 mm (narrow platform (np)), 4.3 mm (regular platform (rp)) and 5 ...

We demonstrate long-distance (≥100-km) synchronization of the phase of a radio-frequency reference over an optical-fiber network without needing to actively stabilize the optical path length. Frequency mixing is used to achieve passive phase-conjugate cancellation of fiber-length fluctuations, ensuring that the phase difference between the reference and synchronized oscillators is independent o...

This paper presents a combined approach based on Prony analysis and radial basis function neural network for monitoring small signal stability and parameter tuning of power system stabilizer. Prony analysis method is used to estimate the modal components of low frequency oscillations associated with synchronous generators. In this method, the measured (simulated) time-domain signal is decompose...

We describe the operation of a laser cooled cesium fountain clock in the quantum limited regime. An ultrastable cryogenic sapphire oscillator is used to measure the short-term frequency stability of the fountain as a function of the number of detected atoms Nat. For Nat varying from 4 3 104 to 6 3 105 the Allan standard deviation of the frequency fluctuations is in excellent agreement with the ...

The saturation spectrum of the P(84) 5-5 transition of 127I2 at 657.483 nm is obtained with the third-harmonic demodulation method using an external cavity diode laser. The laser frequency is modulated by modulating the diode current instead of modulating the cavity length with a piezoelectric transducer (PZT). Current modulation allows a modulation frequency that is higher than PZT modulation....

This paper provides a novel hierarchical control for VSI-based microgrids. The advantage of the provided control scheme is to maintain the frequency and voltage stability and load sharing against large-signal disturbances. A hierarchical control, consisting of three levels, is described. A new control loop based on PI controller, is presented. The new control loop has a great impact on increasi...

The power system stabilizer is used to damp out the low frequency oscillations that improve the small signal stability of the power system. If ignored these low frequency oscillations may lead to cascaded failure of the complete power system. This paper presents the comparative study of conventional power system stabilizer (CPSS) with newly proposed Adaptive Fuzzy Logic Controlled Power System ...

This paper presents a new centralized adaptive method under frequency load shedding. Sometimes, after initial frequency drop following severe disturbances, although the system frequency returns to its permissible value, however, the system might become unstable due to voltage problems. In this regard, the paper proposes a new centralized adaptive load shedding method to enhance the voltage stab...