We investigate the in-line and cross-flow vortex-induced vibrations of a long cylindrical tensioned beam, with length to diameter ratio L/D=200, placed within a linearly sheared oncoming flow, using three-dimensional direct numerical simulation. The study is conducted at three Reynolds numbers, from 110 to 1100 based on maximum velocity, so as to include the transition to turbulence in the wake...

A scale-factor-stabilized fiber-optic gyroscope by deep phase modulation is demonstrated. There are two servo loops included in this system. The first servo loop is used for stabilization of the light intensity output of the fiber-optic gyroscope. The second loop is used to stabilize the phase-modulation index. The third-harmonic frequency of the phase-modulation signal is used for detection of...

This paper presents an analysis that confers new insights into injection pulling and locking of oscillators and the reduction of phase noiseunder locked condition. A graphical interpretation of Adler’s equation predicts the behavior of injection-pulled oscillators in time and frequency domains. An identity derived from the phase and envelope equations expresses the required oscillator nonlinear...

Like virtually all media access control (MAC) protocols for 802.15.4 networks, also ContikiMAC is vulnerable to various denial-of-sleep attacks. The focus of this paper is on countering three specific denial-of-sleep attacks on ContikiMAC, namely ding-dong ditching, pulse-delay attacks, and collision attacks. Ding-dong ditching is when attackers emit interference, inject frames, or replay frame...

The performance of several GPS carrier tracking loops is evaluated using wideband GPS data recorded during strong ionospheric scintillations. The aim of this study is to determine the loop structures and parameters that enable good phase tracking during the power fades and phase dynamics induced by scintillations. Constant-bandwidth and variable-bandwidth loops are studied using theoretical mod...

Multiversion concurrency control schemes are often limited in their practicability due to their storage requirements for multiple versions of the data. However, a class of multiver-sion schemes utilize only the versions, maintained for the purpose of recovery, to improve the concurrency by allowing the concurrent execution of "non conflicting" read-write lock requests on different versions of d...

We have experimentally demonstrated current-injection optical phase-lock loops (OPLLs) based on commercial single-section semiconductor distributed-feedback (DFB) lasers. Using two parallel OPLLs, we have obtained 87% efficient coherent power combining of the two DFB lasers. The rms differential phase error between the two lasers is about 30 degrees .

Retrodirective Phase-Lock Loop Controlled Phased Array Antenna for a Solar Power Satellite System. (December 2004) Samuel John Kokel, B.S., Texas A&M University Chair of Advisory Committee: Dr. Kai Chang This thesis proposes a novel technique using a phase-lock loop (PLL) style phase control loop to achieve retrodirective phased array antenna steering. This novel approach introduces the concept...

The input frequency limit of the conventional zero-crossing digital phase-locked loop (ZCDPLL) is due to the operating time of the digital circuitry inside the feedback loop. A solution that has been previously suggested is the introduction of a time delay in the feedback path of the loop to allow the digital circuits to complete their sample processing before the next sample is received. Howev...

Designing of an analog circuit satisfying the design constraints for desired application is a challenging job. Phase Lock Loop (PLL) is an important analog circuit used in various communication applications such as frequency synthesizer, radio, computer, clock generation, clock recovery, global positioning system, etc. Since all these applications are operating at different frequency, satisfyin...