Optimal Placement of PMU for Fast Robust Power System Dynamic State Estimation using UKF–GBDT Technique

This paper proposes a fast and robust dynamic state estimation technique based on model transformation method using the proposed hybrid technique. The proposed hybrid method is the combination of Unscented Kalman Filter (UKF) and Gradient Boosting Decision Tree (GBDT), hence commonly referred to as the UKF–GBDT technique. The proposed model transformation approach is accomplished by taking the active power generator measured as input variable and derived frequency as rate of change of frequency measurements of phasor measurement units (PMU) as dynamic generator output variable model. The proposed hybrid technique is also formulated to deal with data quality issues, and the rate of change of frequency and frequency measurements may be skewed in the presence of rigorous disruption or communication problems. This permits to obtain discrete-time linear dynamic equations in state space based on the linear Kalman filter (LKF). With this proper control, this model alleviates filter divergence problems, which can be a severe issue if the nonlinear model is utilized in greatly strained operating system conditions, and gives quick estimate of rotor speeds together with angles through transient modes if only the transient stability with control is concerned. In the case of long-term dynamics, the outcome of governor’s response in long-term system dynamics is offset together with mechanical power at rotor speed and the state vector angles for joint evaluation. At last, the performance of the proposed method is simulated in MATLAB/Simulink and the performance is compared to the existing methods like UKF, GBDT and ANN. The proposed technique is simulated under three case studies like IEEE 14-, 30- and 118-bus systems.

DETECTING CYCLE SLIPS IN CARRIER-PHASE MEASURMENTS OF NAVIGATION RECEIVER WITH HIGH STABLE REFERENCE GENERATORS

The paper shows a simple method for detecting cycle slips in the carrier-phase measurements (including single frequency measurements) of navigation receivers with highly stable (hydrogen) reference oscillators by using approximation by high-degree polynomials.

Contamination Analyses of ISS Vehicle Visits

The SAGE III Contamination Monitoring Package detects the contamination environment in the immediate vicinity of the payload using eight Thermoelectric Quartz Crystal Microbalance sensors that telemeter continuous beat frequency measurements to the ground. The single greatest source of contamination measured to date was the SpaceX Cargo Dragon, whose outgassed contaminants chemisorbed to the gold electrodes of the sensors. This paper contains results from the mission’s first three years, including the signals observed from every visible visiting vehicle, the measured effects on the overall payload, and learned lessons to consider for future ISS or TQCM missions.

Effects of Chord Inversion and Bass Patterns on Harmonic Expectancy in Musicians

This study tests the respective roles of pitch-class content and bass patterns within harmonic expectation using a mix of behavioral and computational experiments. In our first two experiments, participants heard a paradigmatic chord progression derived from music theory textbooks and were asked to rate how well different target endings completed that progression. The completion included the progression’s paradigmatic target, different inversions of that chord (i.e., different members of the harmony were heard in the lowest voice), and a “mismatched” target, a triad that shared its lowest pitch with the paradigmatic ending but altered other pitch-class content. Participants generally rated the paradigmatic target most highly, followed by other inversions of that chord, with lowest ratings generally elicited by the mismatched target. This suggests that listeners’ harmonic expectations are sensitive to both bass patterns and pitch-class content. However, these results did not hold in all cases. A final computational experiment was run to determine whether variations in behavioral responses could be explained by corpus statistics. To this end, n-gram chord-transition models and frequency measurements were compiled for each progression. Our findings suggest that listeners rate highly and have stronger expectations about chord progressions that occur frequently and behave consistently within tonal corpora.

Investigation of frequency dependent mechanical properties of porous materials using dynamic mechanical analyzer and frequency-temperature superposition theory

In acoustic design of engineering applications - such as in the acoustic analysis of passenger vehicles - poroelastic materials are of great importance. One of the most influencing properties in determining their noise-reduction potential is the storage modulus. The purpose of this study is to examine the frequency dependence of storage modulus of selected porous acoustic materials at least up to 1000 Hz. This is executed by using the combined use of dynamic mechanical analyzer and frequency-temperature superposition theory. All other methods for measuring the storage modulus fall short in determining frequency-dependence above 100 Hz: quasi-static mechanical analyzer is mostly used for determining an averaged constant value deduced from low-frequency measurements, while the usage of an electromagnetic shaker capable for high-frequency excitation may include effects of fluid motion inside the pores, thus significantly modifying the results. Frequency-temperature superposition enables to determine the storage modulus values in a wide frequency range, based on low-frequency measurements, where fluid-structure interaction is negligible. It was found that the modulus varied significantly up to and beyond 1000 Hz, and thus, acoustical characterization of these materials can be significantly improved using the proposed method. The work concludes with recommendations to improve the accuracy of the results.

A Review of the Research and Development of High-Frequency Measurement Technologies Used for Nonlinear Dynamics of Drillstring

High-frequency measurements can provide much more new insights for drillstring dynamics compared to traditional instruments, leading to a new realm of understanding of drillstring behaviors in great detail than before. In this paper, data acquisition tools with high-frequency sample rates and the data processing are introduced. Based on high-frequency data, progress of drilling dynamics is summarized, including new understandings of low-frequency drillstring dynamics, high-frequency torsional oscillations (HFTOs), and high-frequency axial oscillations (HFAOs) and new findings for the coupling of vibrations and motions, as well as models and simulation methods to deeply comprehend high-frequency dynamics of drillstring. High-frequency measurements have been used for enabling drillers to improve drill performance, especially for field decision making, BHA selection, and bit design, usually through the ways of minimizing vibrations to obtain high-efficient drilling conditions, the high-frequency response near bit can also be used for lithology identification during drilling. Though there still exists a gap between research perspective and drilling practice, the industry of high-frequency measurements has gotten off a good start, which has huge potential to avoid nonproductive time thereupon reducing drilling cost in the future.