Wind Turbine Generator Condition Monitoring via the Generator Control Loop

This thesis focuses on the development of condition monitoring techniques for application in wind turbines, particularly for offshore wind turbine driven doubly fed induction generators. The work describes the significant development of a physical condition monitoring Test Rig and its MATLAB Simulink model to represent modern variable speed wind turbine and the innovation and application of the rotor side control signals for the generator fault detection. Work has been carried out to develop a physical condition monitoring Test Rig from open loop control, with a wound rotor induction generator, into closed loop control with a doubly fed induction generator. This included designing and building the rotor side converter, installing the back-to-back converter and other new instrumentation. Moreover, the MATLAB Simulink model of the Test Rig has been developed to represent the closed loop control, with more detailed information on the Rig components and instrumentation and has been validated against the physical system in the time and frequency domains. A fault detection technique has been proposed by the author based on frequency analysis of the rotor-side control signals, namely; d-rotor current error, q-rotor current error and q-rotor current, for wind turbine generator fault detection. This technique has been investigated for rotor electrical asymmetry on the physical Test Rig and its MATLAB Simulink model at different fixed and variable speed conditions. The sensitivity of the each proposed signal has been studied under different operating conditions. Measured and simulated results are presented, a comparison with the results from using stator current and total power has been addressed and the improvement in condition monitoring detection performance has been demonstrated in comparison with previous methods, looking at current, power and vibration analysis

Editorial for the Special Issue on “Emerging Trends in Phononic Crystals”

From MDPI via Jisc Publications RouterHistory: accepted 2021-07-30, pub-electronic 2021-08-03Publication status: PublishedOver the past three decades, the study of phononic crystals (PCs) has rapidly evolved into a prominent research field offering a versatile platform for the creation of structured materials with salient properties [...

Primjena umjetne toplinske stimulacije kao novi pristup za indukciju tendinopatije u magaraca

Animal models for tendonitis are essential for studying the disease’s mechanism and pathogenesis, and evaluating different therapeutic protocols. The temperature seems to play a significant role in tendinitis initiation. The aim of this study was the generation of a novel, safe and cheap tendinitis model, and validation of its reliability. The effect of microwave diathermy (30 watts for 30 min) on the flexor tendons of donkeys as animal models was investigated after 15, 30 and 60 days. The evaluation was based on geometric analysis, ultrasonography, histomorphometric analysis and scanning electron microscopy (SEM). Microwave diathermy was capable of successfully inducing well-defined lesions in the superficial digital flexor tendon (SDFT) as well as the deep digital flexor tendon (DDFT). The results showed that all the animals exhibited signs of lameness, starting on day 15 and reaching on maximum on day 30. A significant increase in limb circumference was also detected on day 30 (P<0.05). Furthermore, the geometrical analysis of the proportion of induced lesion (PIL) in correlation with the tendon diameter, revealed that PIL was at the maximum width on day 30 (20.6 ± 1.2% for SDFT and 15.7 ± 0.7% for DDFT), as detected by ultrasound. Moreover, a high number of rounded tenocytes, bleeding, severe matrix disruption, and an increase in fiber thickness were detected by histomorphometric analysis. Also, the matrix alignment was severely disrupted in both SDFT and DDFT by day 30, as confirmed by SEM. In conclusion, using microwave diathermy for induction of tendonitis in donkey is a reliable, minimally invasive, and cost-effective tendonitis model.Uporaba životinjskih modela je neophodna za proučavanje mehanizma bolesti, patogeneze i za procjenu protokola liječenje tendinitisa. Čini se da temperatura igra značajnu ulogu pri nastajanju tendinitisa. Cilj istraživanja bio je stvaranje novog, sigurnog i jeftinog modela za proučavanje tendinitisa te potvrda njegove pouzdanosti. Učinak mikrovalne dijatermije (30 vata tijekom 30 min) na tetive fleksora u magaraca kao životinjskih modela istraživan je nakon 15, 30 i 60 dana. Procjena se temeljila na geometrijskoj analizi, ultrazvuku, histomorfometrijskoj analizi i skenirajućoj elektronskoj mikroskopiji (SEM). Mikrovalna dijatermija uspješno je inducirala dobro definirane lezije u površinskoj digitalnoj tetivi fleksora (SDFT) kao i dubokoj digitalnoj tetivi fleksora (DDFT). Rezultati su pokazali da su sve životinje pokazivale znakove hromosti, počevši od 15. dana i dostižući maksimum 30. dana. Također, 30. dana je uočeno znakovito (P<0,05) povećanje opsega ekstremiteta. Nadalje, uporabom ultrazvuka i primjenom geometrijske analize udjela inducirane lezije (PIL) u korelaciji s promjerom tetive, ustanovljeno je da je PIL bio maksimalne širine 30. dana (20,6 ± 1,2% za SFT i 15,7 ± 0,7% za DDFT). Osim toga, histomorfometrijskom analizom otkriven je povećan broj zaobljenih tenocita, krvarenje, teži poremećaji u matriksu i povećanje debljine vlakana. Do 30. dana, SEM analiza je pokazala izražene poremećaje u poravnavanju matriksa i u SDFT i u DDFT. Zaključno, primjena mikrovalne dijatermije za indukciju tendinitisa kod magaraca je pouzdan, minimalno invazivan i troškovno učinkovit životinjski model za proučavanje ove bolesti

Building a neural speech recognizer for quranic recitations

This work is an effort towards building Neural Speech Recognizers system for Quranic recitations that can be effectively used by anyone regardless of their gender and age. Despite having a lot of recitations available online, most of them are recorded by professional male adult reciters, which means that an ASR system trained on such datasets would not work for female/child reciters. We address this gap by adopting a benchmark dataset of audio records of Quranic recitations that consists of recitations by both genders from different ages. Using this dataset, we build several speaker-independent NSR systems based on the DeepSpeech model and use word error rate (WER) for evaluating them. The goal is to show how an NSR system trained and tuned on a dataset of a certain gender would perform on a test set from the other gender. Unfortunately, the number of female recitations in our dataset is rather small while the number of male recitations is much larger. In the first set of experiments, we avoid the imbalance issue between the two genders and down-sample the male part to match the female part. For this small subset of our dataset, the results are interesting with 0.968 WER when the system is trained on male recitations and tested on female recitations. The same system gives 0.406 WER when tested on male recitations. On the other hand, training the system on female recitations and testing it on male recitation gives 0.966 WER while testing it on female recitations gives 0.608 WER

Effect of Quercetin Nanoparticles on Hepatic and Intestinal Enzymes and Stress-Related Genes in Nile Tilapia Fish Exposed to Silver Nanoparticles

The current study investigated the potential mitigative effect of quercetin nanoparticles (QNPs) against silver nanoparticle-induced toxicity in Nile tilapia. Fish were grouped into the control, fish exposed to 1.98 mg L–1 silver nanoparticle (AgNPs), fish that received 400 mg L–1 24 QNPs, and fish that received both QNPs and AgNPs at the same concentrations for 60 days. The moisture and ash contents of the AgNP group were significantly higher than those of the other groups. In contrast, the crude lipid and protein were decreased in the whole body. AgNPs significantly increased serum levels of ALT, AST, total cholesterol, and triglycerides and decreased glycogen and growth hormone. The activities of antioxidants were significantly inhibited, and the levels of oxidative damage were increased in the liver of the AgNP group. AgNPs upregulated the expression of hepatic HSP70, caspase3, and p53 genes. AgNPs inhibited intestinal enzyme activities, increased intestinal bacterial, and Aeromonas counts, and increased Ag residues in the liver. These findings indicate the oxidative and hepatoxic effects of AgNPs. QNPs enhanced and restored physiological parameters and health status under normal conditions and after exposure to AgNPs

Towards Building a Speech Recognition System for Quranic Recitations: A Pilot Study Involving Female Reciters

This paper is the first step in an effort toward building automatic speech recognition (ASR) system for Quranic recitations that caters specifically to female reciters. To function properly, ASR systems require a huge amount of data for training. Surprisingly, the data readily available for Quranic recitations suffer from major limitations. Specifically, the currently available audio recordings of Quran recitations have massive volume, but they are mostly done by male reciters (who have dedicated most of their lives to perfecting their recitation skills) using professional and expensive equipment. Such proficiency in the training data (along with the fact that the reciters come from a specific demographic group; adult males) will most likely lead to some bias in the resulting model and limit their ability to process input from other groups, such as non-/semi-professionals, females or children. This work aims at empirically exploring this shortcoming. To do so, we create a first-of-its-kind (to the best of our knowledge) benchmark dataset called the Quran recitations by females and males (QRFAM) dataset. QRFAM is a relatively big dataset of audio recordings made by male and female reciters from different age groups and proficiency levels. After creating the dataset, we experiment on it by building ASR systems based on one of the most popular open-source ASR models, which is the celebrated DeepSpeech model from Mozilla. The speaker-independent end-to-end models, that we produce, are evaluated using word error rate (WER). Despite DeepSpeech’s known flexibility and prowess (which is shown when trained and tested on recitations from the same group), the models trained on the recitations of one group could not recognize most of the recitations done by the other groups in the testing phase. This shows that there is still a long way to go in order to produce an ASR system that can be used by anyone and the first step is to build and expand the resources needed for this such as QRFAM. Hopefully, our work will be the first step in this direction and it will inspire the community to take more interest in this problem

Molecular detection of Epstein-Barr virus among Sudanese patients diagnosed with Hashimoto’s thyroiditis

Objectives: Hashimoto’s thyroiditis (HT) is the most common cause of hypothyroidism. The exact mechanism initiating the development of HT is not yet clear. This study aimed to investigate the correlation between HT and the presence of Epstein-Barr virus (EBV) in a Sudanese population. Results: EBV-LMP1 was detected in 11.1% of HT cases, which is consistent with previous studies. Studies have reported a wide range of frequencies indicating the presence of EBV in HT, and patients with autoimmune thyroiditis have increased titers of anti-EBV antibodies in their sera compared to healthy subjects. Intrathyroidal EBV-infected B cells may be responsible for the increased risk of development of B-cell lymphoma in the thyroid gland in patients with autoimmune thyroiditis. Our study suggests that regular follow-up is necessary for patients diagnosed with HT and are positive for EBV, as antiviral therapy is not applicable due to the risk of thyroid dysfunction. The study suggests an association between EBV and HT, but causation cannot be determined. The study also highlights the need for further research to determine the viral role and correlate it with the severity and progression of HT.</p

Molecular detection of Epstein-Barr virus among Sudanese patients diagnosed with Hashimoto’s thyroiditis

Objectives: Hashimoto’s thyroiditis (HT) is the most common cause of hypothyroidism. The exact mechanism initiating the development of HT is not yet clear. This study aimed to investigate the correlation between HT and the presence of Epstein-Barr virus (EBV) in a Sudanese population. Results: EBV-LMP1 was detected in 11.1% of HT cases, which is consistent with previous studies. Studies have reported a wide range of frequencies indicating the presence of EBV in HT, and patients with autoimmune thyroiditis have increased titers of anti-EBV antibodies in their sera compared to healthy subjects. Intrathyroidal EBV-infected B cells may be responsible for the increased risk of development of B-cell lymphoma in the thyroid gland in patients with autoimmune thyroiditis. Our study suggests that regular follow-up is necessary for patients diagnosed with HT and are positive for EBV, as antiviral therapy is not applicable due to the risk of thyroid dysfunction. The study suggests an association between EBV and HT, but causation cannot be determined. The study also highlights the need for further research to determine the viral role and correlate it with the severity and progression of HT.</p

Liraglutide effects on glycemic control and weight in patients with Type 2 Diabetes mellitus: a real-world, observational study and brief narrative review

Background Glycemic control and weight gain are two essential considerations in the pharmacological management of type 2 diabetes mellitus. Pharmacological agents are effective in lowering blood glucose levels but may result in significant weight gain. Liraglutide effectively maintains glycemic control while reducing weight. Methods This is a real-world study and brief narrative review of the effects of liraglutide on glycemic control and weight in adult patients with type 2 diabetes mellitus. The study uses data extracted from the electronic health record of the Ministry of National Guard-Health Affairs. Results In this study of 348 subjects, there was a statistically significant reduction in hemoglobin A1c of 0.9% (P < .0001) and weight of 2.3 kg (P < .0001). The majority (77.3%) were on concomitant insulin. Subjects with a baseline hemoglobin A1c greater than 9% had a significantly greater reduction than those below 9% (−0.7%; P < .0001). Those with a weight more than 100 kg had a significantly greater reduction than those below 100 kg (-0.9 kg; P = .0096). Conclusion In this real-world, observational study, liraglutide was shown to be effective in improving glycemic control and reducing weight in adult patients with type 2 diabetes mellitus

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London