Which Neural Network to Choose for Post-Fault Localization, Dynamic State Estimation, and Optimal Measurement Placement in Power Systems?

We consider a power transmission system monitored using phasor measurement units (PMUs) placed at significant, but not all, nodes of the system. Assuming that a sufficient number of distinct single-line faults, specifically the pre-fault state and the (not cleared) post-fault state, are recorded by the PMUs and are available for training, we first design a comprehensive sequence of neural networks (NNs) locating the faulty line. Performance of different NNs in the sequence, including linear regression, feed-forward NNs, AlexNet, graph convolutional NNs, neural linear ordinary differential equations (ODEs) and neural graph-based ODEs, ordered according to the type and amount of the power flow physics involved, are compared for different levels of observability. Second, we build a sequence of advanced power system dynamics–informed and neural ODE–based machine learning schemes that are trained, given the pre-fault state, to predict the post-fault state and also, in parallel, to estimate system parameters. Finally, third and continuing to work with the first (fault localization) setting, we design an (NN-based) algorithm which discovers optimal PMU placement.

Factors affecting the accuracy and reliability of the measurement of anti-Müllerian hormone concentration in the clinic

Objective We aimed to identify the factors that influence serum anti-Müllerian hormone (AMH) concentration measurements. Methods We collected serum samples between May and September 2018 and compared the effect on AMH concentration measured by ELISA of conditions including venepuncture, storage time, storage temperature, locations of the reaction microplate, and the use of the oral contraceptive pill and gonadotrophin-releasing hormone (GnRH). Results AMH concentration was not affected by food intake but was affected by haemolysis. It was also much higher in samples on the edge of the ELISA microtitre plate. AMH concentration increased after incubation at room temperature for 1 day, 4°C for 3 days, −20°C for 1 month and −40°C for 4 months, but no change occurred during storage at −80°C for 9 months. AMH concentration was high in patients following GnRH agonist treatment but was not affected by oral contraceptives. Conclusions No fasting is required prior to AMH measurement. Placement of serum samples on the edge of microtitre plates affects the results of the AMH ELISA. If serum samples cannot be assayed immediately, it is best to store them at −80°C. Basal AMH concentration cannot be used as a measure of ovarian reserve after GnRH agonist treatment.