Machine Learning Based Method for Impedance Estimation and Unbalance Supply Voltage Detection in Induction Motors.

Induction motors (IMs) are widely used in industrial applications due to their advantages over other motor types. However, the efficiency and lifespan of IMs can be significantly impacted by operating conditions, especially Unbalanced Supply Voltages (USV), which are common in industrial plants. Detecting and accurately assessing the severity of USV in real-time is crucial to prevent major breakdowns and enhance reliability and safety in industrial facilities. This paper presented a reliable method for precise online detection of USV by monitoring a relevant indicator, denominated by negative voltage factor (NVF), which, in turn, is obtained using the voltage symmetrical components. On the other hand, impedance estimation proves to be fundamental to understand the behavior of motors and identify possible problems. IM impedance affects its performance, namely torque, power factor and efficiency. Furthermore, as the presence of faults or abnormalities is manifested by the modification of the IM impedance, its estimation is particularly useful in this context. This paper proposed two machine learning (ML) models, the first one estimated the IM stator phase impedance, and the second one detected USV conditions. Therefore, the first ML model was capable of estimating the IM phases impedances using just the phase currents with no need for extra sensors, as the currents were used to control the IM. The second ML model required both phase currents and voltages to estimate NVF. The proposed approach used a combination of a Regressor Decision Tree (DTR) model with the Short Time Least Squares Prony (STLSP) technique. The STLSP algorithm was used to create the datasets that will be used in the training and testing phase of the DTR model, being crucial in the creation of both features and targets. After the training phase, the STLSP technique was again used on completely new data to obtain the DTR model inputs, from which the ML models can estimate desired physical quantities (phases impedance or NVF).

Anthropogenic food subsidies reshape the migratory behaviour of a long-distance migrant.

Bird migratory journeys are often long and hostile, requiring high energetic expenditure, and thus forcing birds to pause between migratory flights. Stopover sites allow migrants to replenish fuel reserves and rest, being crucial for the success of migration. Worldwide, the increasing accumulation of waste on landfills and rubbish dumps has been described to provide superabundant food resources for many bird species not only during the breeding and wintering seasons but also during migration, being used as stopover sites. Using GPS-tracking data of juvenile white storks (Ciconia ciconia) during their first migration from the Iberia Peninsula to the sub-Saharan wintering grounds, we uncover the effects of stopping en route on individual migratory performance. Particularly, we examine the benefits of stopping at artificial sites (landfills and rubbish dumps) when compared to natural stopover sites (wetlands, agricultural or desert areas) and explore the influence of anthropogenic food resources on storks' migratory strategies. Overall, white storks spent up to one-third of the migration in stopovers. We found that birds that stopped for longer periods made more detours, increasing migration duration by half a day for each stopover day. Stopping more often did not reflect on increasing in-flight energetic efficiency nor the likelihood of completing the migration. Juvenile storks used artificial sites in 80 % of the stopover days, spending 45 % less time and 10 % less energy foraging than when using natural stopovers. While stopping in landfills did not translate into differences in migratory performance, individuals in poor body condition possibly rely on these sites to improve body weight before proceeding, enabling them to successfully complete migration. Artificial stopover sites are attractive and likely increase the number and duration of stops for white storks. Even though the consequences of arriving late at the wintering grounds are unknown, it can lead to cascading consequences, influencing individual fitness and population dynamics.

Characterization and comparison of commercial oils used for human embryo culture.

STUDY QUESTION: Are there significant differences between the available commercial oil brands used for human IVF? SUMMARY ANSWER: Important differences have been detected among the tested oil brands in their potential to stabilize culture conditions and, more importantly, in their direct effect on embryo development and viability. WHAT IS KNOWN ALREADY: Mineral oil is a critical component of the human culture system due to its protective and stabilizing roles during in vitro embryo development. Many different oils are available on the market, with differences in their viscosity, density and overall quality. STUDY DESIGN, SIZE, DURATION: Thirteen different commercial oil brands were compared. PARTICIPANTS/MATERIALS, SETTING, METHODS: Each oil was firstly analyzed to assess its viscosity, density, peroxide value and potential oxidation. Secondly, the capacity of each oil to reduce pH, osmolality and temperature fluctuations during embryo culture and manipulation was compared. Lastly, a sensitive mouse embryo assay (MEA) protocol, previously optimized to detect toxicity in oils samples, was used to compare the overall quality of the different brands in terms of embryo developmental rates up to the blastocyst stage. At the end of the MEAs, a triple labeling protocol was applied to analyze Oct4+ cells, apoptotic cells and total cell counts in the blastocysts obtained by fluorescence microscopy. MAIN RESULTS AND THE ROLE OF CHANCE: Significant divergences were detected in the rise of osmolality and the equilibration and stability of pH between different oils, which could be correlated to their physico-chemical characteristics. In particular, oil samples with a higher viscosity tended to offer an additional protection against fluctuations in the culture conditions, however, the differences in temperature stability between oils were minor. Two out of the 13 oil samples, which were commercially available, were identified as embryo-toxic by applying the MEA protocol with increased sensitivity for toxicity detection. Additionally, substantial differences in the total number of cells and the number of cells in the inner cell mass of the obtained blastocysts were also detected between oil groups. LIMITATIONS, REASONS FOR CAUTION: A single lot of oil was used for each brand and, thus, lot-to-lot variations in oil quality could not be determined. However, several bottles from the same oil were included to account for potential intra-lot variability. WIDER IMPLICATIONS OF THE FINDINGS: Commercial oils differ in both their physical characteristics and their performance in maintaining the stability of the culture conditions during in vitro embryo culture. Oil selection is important for embryo culture success. Additionally, the detection of embryo-toxic oils which had already been released to the human IVF market showcases the importance of applying sensitive MEA protocols for a better detection of toxicity in this type of samples. STUDY FUNDING/COMPETING INTEREST(S): This study was privately funded. TRIAL REGISTRATION NUMBER: N/A.

Factors of the human embryo culture system that may affect media evaporation and osmolality.

STUDY QUESTION: Which lab-related factors impact the culture system's capacity to maintain a stable osmolality during human embryo culture? SUMMARY ANSWER: Incubator humidity, the volume of mineral oil, the type of culture media and the design of time-lapse dishes have been identified as important parameters that can cause an impact on media evaporation and consequently osmolality during culture. WHAT IS KNOWN ALREADY: Culture medium is a critical component in human embryo culture. Minimizing its evaporation during culture is an adequate strategy to stabilize osmolality and, as a result, improving culture conditions and clinical outcomes. STUDY DESIGN, SIZE, DURATION: The studied variables included media composition and supplementation; volume of mineral oil; incubator humidification; and the type of dish and incubator used. Additionally, six time-lapse dish models were compared in their ability to prevent evaporation. PARTICIPANTS/MATERIALS, SETTING, METHODS: Dishes were incubated in parallel to analyze osmolality during culture between groups: synthetic oviductal medium enriched with potassium versus human tubal fluid medium; protein versus no protein supplementation; dry versus humid atmosphere; high versus low volume of mineral oil. Additionally, media evaporation was compared between six models of time-lapse dishes with distinct designs, cultured in a joint incubator. Two of them were retested in their corresponding incubator to analyze the dish-incubator fit. Daily osmolality measurements were compared between groups. Linear regression was performed to analyze evaporation rates. MAIN RESULTS AND THE ROLE OF CHANCE: Protein supplementation did not significantly affect evaporation. Contrarily, humidity levels inside the incubators, the volume of mineral oil and the type of culture media, played an important role in osmolality stabilization. The design of time-lapse dishes and their recommended preparation protocol heavily influenced their evaporation rates, which were further altered by each incubator's characteristics. Media with initially high osmolalities had a bigger risk of reaching hypertonic levels during culture. LIMITATIONS, REASONS FOR CAUTION: While numerous, the studied variables are limited and therefore other factors could play a role in osmolality dynamics, as well. Incontrollable atmospheric factors could also result in some variation in the observed results between different centers and laboratories. WIDER IMPLICATIONS OF THE FINDINGS: Published literature has extensively described how hypertonic media may impair embryo development and negatively affect clinical outcomes; therefore, maintaining a stable osmolality during culture should be considered essential. This work is of interest both for embryologists when analyzing their culture system and methodologies, as well as manufacturers in charge of designing IVF consumables. STUDY FUNDING/COMPETING INTEREST(S): This study was privately funded. TRIAL REGISTRATION NUMBER: N/A.