Data-Driven Low-Frequency Oscillation Event Detection Strategy for Railway Electrification Networks.

Low-frequency oscillations (LFO) occur in railway electrification systems due to the incorporation of new trains with switching converters. As a result, the increased harmonic content can cause catenary stability problems under certain conditions. Most of the research published on this topic to date is focused on modelling the event and analysing it using frequency spectrums. However, in recent years, due to the new technologies linked to Big Data (BD) and data mining (DM), a new opportunity to study and detect LFO events by means of machine-learning (ML) methods has emerged. Trains continuously collect data from the most important catenary variables, which offers new resources for analysing this type of event. Therefore, this article presents the design and implementation of a data-driven LFO event detection strategy for AC railway network scenarios. Compared to previous investigations, a new approach to analyse and detect LFO events, based on field data and ML, is presented. To obtain the most appropriate detection approach for the context of this application, on the one hand, this investigation includes a comparison of machine-learning algorithms (support vector machine, logistic regression, random forest, k-nearest neighbours, naïve Bayes) which have been trained with real field data. On the other hand, an analysis of key parameters and features to optimize event detection is also included. Thus, the most significant result of this work is the high metric values of the solution, reaching values above 97% in accuracy and 93% in F-1 score with the random forest algorithm. In addition, the applicability and training of data-driven methods with real field data are demonstrated. This automatic detection strategy can help with speeding up and improving LFO detection tasks that used to be performed manually. Finally, it is worth mentioning that this research has been structured based on the CRISP-DM methodology, established as the de facto approach for industrial DM projects.

Small bowel angioedema. An unusual condition with an interesting differential diagnosis.

We present the case of a 35-year-old woman with a prior history of hereditary angioedema (HA) who was admitted to the emergency department with epigastric pain, vomiting and sweating. Laboratory tests showed raised APR levels (CRP and leukocytosis).

Data-Driven Fault Diagnosis for Electric Drives: A Review.

The need to manufacture more competitive equipment, together with the emergence of the digital technologies from the so-called Industry 4.0, have changed many paradigms of the industrial sector. Presently, the trend has shifted to massively acquire operational data, which can be processed to extract really valuable information with the help of Machine Learning or Deep Learning techniques. As a result, classical Condition Monitoring methodologies, such as model- and signal-based ones are being overcome by data-driven approaches. Therefore, the current paper provides a review of these data-driven active supervision strategies implemented in electric drives for fault detection and diagnosis (FDD). Hence, first, an overview of the main FDD methods is presented. Then, some basic guidelines to implement the Machine Learning workflow on which most data-driven strategies are based, are explained. In addition, finally, the review of scientific articles related to the topic is provided, together with a discussion which tries to identify the main research gaps and opportunities.

A Hybrid Sensor Fault Diagnosis for Maintenance in Railway Traction Drives.

Due to the importance of sensors in railway traction drives availability, sensor fault diagnosis has become a key point in order to move from preventive maintenance to condition-based maintenance. Most research works are limited to sensor fault detection and isolation, but only a few of them analyze the types of sensor faults, such as offset or gain, with the aim of reconfiguring the sensor in order to implement a fault tolerant system. This article is based on a fusion of model-based and data-driven techniques. First, an observer-based approach, using a Sliding Mode observer, is utilized for sensor fault reconstruction in real time. Then, once the fault is detected, a time window of sensor measurements and sensor fault reconstruction is sent to the remote maintenance center for fault evaluation. Finally, an offline processing is carried out to discriminate between gain and offset sensor faults, in order to get a maintenance decision-making to reconfigure the sensor during the next train stop. Fault classification is done by means of histograms and statistics. The technique here proposed is applied to the DC-link voltage sensor in a railway traction drive and is validated in a hardware-in-the-loop platform.

Integral Sensor Fault Detection and Isolation for Railway Traction Drive.

Due to the increasing importance of reliability and availability of electric traction drives in Railway applications, early detection of faults has become an important key for Railway traction drive manufacturers. Sensor faults are important sources of failures. Among the different fault diagnosis approaches, in this article an integral diagnosis strategy for sensors in traction drives is presented. Such strategy is composed of an observer-based approach for direct current (DC)-link voltage and catenary current sensors, a frequency analysis approach for motor current phase sensors and a hardware redundancy solution for speed sensors. None of them requires any hardware change requirement in the actual traction drive. All the fault detection and isolation approaches have been validated in a Hardware-in-the-loop platform comprising a Real Time Simulator and a commercial Traction Control Unit for a tram. In comparison to safety-critical systems in Aerospace applications, Railway applications do not need instantaneous detection, and the diagnosis is validated in a short time period for reliable decision. Combining the different approaches and existing hardware redundancy, an integral fault diagnosis solution is provided, to detect and isolate faults in all the sensors installed in the traction drive.

DC-Link Voltage and Catenary Current Sensors Fault Reconstruction for Railway Traction Drives.

Due to the importance of sensors in control strategy and safety, early detection of faults in sensors has become a key point to improve the availability of railway traction drives. The presented sensor fault reconstruction is based on sliding mode observers and equivalent injection signals, and it allows detecting defective sensors and isolating faults. Moreover, the severity of faults is provided. The proposed on-board fault reconstruction has been validated in a hardware-in-the-loop platform, composed of a real-time simulator and a commercial traction control unit for a tram. Low computational resources, robustness to measurement noise, and easiness to tune are the main requirements for industrial acceptance. As railway applications are not safety-critical systems, compared to aerospace applications, a fault evaluation procedure is proposed, since there is enough time to perform diagnostic tasks. This procedure analyses the fault reconstruction in the steady state, delaying the decision-making in some seconds, but minimising false detections.

Synthesis of a new cytotoxic cephalostatin/ritterazine analogue from hecogenin and 22-epi-hippuristanol.

A new cephalostatin/ritterazine analogue was prepared from the commercially available hecogenin acetate and the natural cytotoxic steroid 22-epi-hippuristanol. The method involved the reductive dimerization of enaminoketones (condensation of alpha-aminoketones) and condensation between an enaminoketone and an alpha-hydroxyketone. The new analogue showed higher cytotoxic activity than the cytotoxic 22-epi-hippuristanol against MDA-MB-231, A-549 and HT-29 cultured tumor cell lines.

Isolation, biological significance, synthesis, and cytotoxic evaluation of new natural parathiosteroids A-C and analogues from the soft coral Paragorgia sp.

Three unusual new steroid thioesters, parathiosteroids A-C (1a-3a), were isolated from the 2-propanol extract of the soft coral Paragorgia sp. collected in Madagascar. Their structures, determined by detailed spectroscopic analysis, were confirmed by synthesis and represent the first isolation of natural steroids bearing a C22 thioester in their side chain. These compounds displayed cytotoxicity against a panel of three human tumor cell lines at the micromolar level. The preparation of several analogues revealed structure/activity relationships in this type of steroids, for example, that the XCH2CH2NHCOCH3 moiety (X = S, O, NH) in the side chain is essential for the antiproliferative activity, and a low degree of oxidation in the A-ring results in higher bioactivity. These natural products could be biosynthetic intermediates in the steroid side chain degradation pathway involving activation with CoA and beta-oxidations.

Gossypiboma Following Emergency Nephrectomy for Wunderlich Syndrome.

We describe the imaging findings of a case of an intra-abdominal gossypiboma (retained surgical sponge) in an asymptomatic 61-year-old man who underwent an emergency nephrectomy because of a Wunderlich syndrome secondary to a renal cell carcinoma. A follow-up computed tomography was performed 4 months after the emergency surgery and showed an extraperitoneal lesion with gas bubbles and radiopaque markings in the left hemiabdomen, consistent with a retained surgical sponge ("gossypiboma" or "textiloma") in the anterior pararenal space. The patient underwent scheduled surgery for extraction of the textiloma.

Preoperative Embolization of a Posterior Mediastinal Lipid-Poor Angiolipoma Mimicking a Paravertebral Nerve Sheath Tumor.

Mediastinal angiolipomas are extremely rare tumors within the thorax, and only 6 cases have been previously reported in the literature. We describe the case of a lipid-poor angiolipoma within the posterior mediastinum of a 63-year-old man who complained of chest pain. Interestingly, initial imaging of the posterior mediastinal mass of our patient suggested a nerve sheath tumor. A specimen from a percutaneous transthoracic core needle biopsy confirmed an angiolipoma. We decided to preoperatively embolize the posterior mediastinal mass to reduce intraoperative bleeding and to facilitate the excision of the tumor.

Synthesis and evaluation of new 6-hydroximinosteroid analogs as cytotoxic agents.

Taking into account the structural requirements for cytotoxicity, several new hydroximinosteroid derivatives have been prepared and evaluated for their cytotoxic activity against A-549, H116, PSN1, and T98G cultured tumor cell lines in order to obtain further information on the potential pharmacophoric core of this type of compound. The influence of the oxygenated position in the A ring, the presence of an additional oxygenated position at C-7 and C-16, and a fluorinated position at C-5 were considered in order to study the structure-activity relationships. The results reveal the importance of oxygenated positions in the A ring (e.g., 4,5-epoxide showed an IC50 value against HCT-116 under micromolar level) for an increase in cytotoxic activity in this type of compound. Furthermore, they showed an important selectivity toward colon tumor line (HCT-116).

Síndrome de Sturge-Weber sin nevus facial: angiomatosis leptomeníngea frontal con evolución favorable / Sturge-Weber syndrome without facial nevus: frontal leptomeningeal angiomatosis with favourable development

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Calcificaciones cerebrales en la enfermedad celíaca. Diagnóstico diferencial con el síndrome de Sturge-Weber atípico / Intracranial calcifications in celiac disease: inclusion of atypical Sturge-Weber syndrome in the differential diagnosis

En la última década se ha descrito la asociación entre enfermedad celíaca, epilepsia y calcificaciones cerebrales. La morfología y localización de estas calcificaciones son similares a las observadas en el síndrome de Sturge-Weber, por lo que muchos pacientes epilépticos con enfermedad celíaca silente han sido diagnosticados de síndrome de Sturge-Weber atípico. Presentamos un caso de enfermedad celíaca en un varón de 35 años de edad que mostró calcificaciones cerebrales, haciendo hincapié en los signos radiológicos que ayudan al diagnóstico diferencial con el síndrome de Sturge-Weber atípico. La instauración temprana del tratamiento adecuado (dieta sin gluten), mejora en muchos casos el cuadro clínico epiléptico, lo que da mayor relevancia al diagnóstico (AU)