A brief status on condition monitoring and fault diagnosis in wind energy conversion systems

International audienceThere is a constant need for the reduction of operational and maintenance costs of Wind Energy Conversion Systems (WECSs). The most efficient way of reducing these costs would be to continuously monitor the condition of these systems. This allows for early detection of the degeneration of the generator health, facilitating a proactive response, minimizing downtime, andmaximizing productivity. Wind generators are also inaccessible since they are situated on extremely high towers, which are normally 20 mor more in height. There are also plans to increase the number of offshore sites increasing the need for a remote means of WECS monitoring that eliminates some of the difficulties faced due to accessibility problems. Therefore and due to the importance of conditionmonitoring and fault diagnosis in WECS (blades, drive trains, and generators), and keeping in mind the need for future research, this paper is intended as a brief status describing different types of faults, their generated signatures, and their diagnostic schemes

Wind Energy Conversion Systems Fault Diagnosis Using Wavelet Analysis

International audienceThis paper deals with the investigation of a specific transient technique suitable for electrical and mechanical failure diagnosis in an induction generator based wind turbine. The investigated technique is a combination of the Discrete Wavelet transform, statistics and the energy. Experimental investigations carried out on a 1.1-kW induction generator based test bench show that the proposed technique can unambiguously diagnose failures under transient conditions

Comparaison de différentes méthodes avancées de traitement de signal pour la détection et le diagnostic de défauts dans les machines asynchrones (application aux éoliennes)

La détection de défauts et leur diagnostic jouent un rôle industriel primordial. En effet, ils contribuent, par une détection rapide et précoce, à faire gagner des points de disponibilité et de production aux capitaux investis dans l outil de production. Le regain d intérêt manifesté par les différents secteurs industriels et par le monde de la recherche démontre que le domaine de la détection de défauts et leur diagnostic est un créneau très porteur. Durant ces dernières années, de nombreuses techniques ont été développées pour la détection de défauts dans les actionneurs électriques ; entre autres les techniques de traitement du signal appliquées au courant statorique dans le cas particulier des machines asynchrones. Ceci nous amène donc à l objectif de celle thèse où il sera question de comparer et analyser les méthodes avancées de traitement de signal pour la détection et le diagnostic de défauts dans les machines asynchrones spécifiques aux éoliennes. Dans un premier temps, un état de l art présente les différents types d énergies fossiles et renouvelables et met en relief l importance de l énergie éolienne. Il est ensuite présenté un bref aperçu des principales défaillances affectant la machine asynchrone d une éolienne. Ceci permet alors d introduire différentes techniques de traitement de signal spécifiques à l application éolienne et de mettre en évidence les principales limitations des techniques spécifiques à l application moteur. Partant du caractère non stationnaire du courant statorique (en fonctionnement éolien et à l apparition d un défaut), il a alors été procédé au test de techniques spécifiques ; entre autres le temps-fréquence et les ondelettes. Ces techniques ont été ensuite mises à profit pour la réalisation d un outil de type Matlab-Simulink® dédié à la surveillance de l état de la génératrice asynchrone d une éolienne.Fault detection and diagnosis play a vital role in industry. In fact, they help invested capitals to earn production and availability points in the production process. The increasing interest of different industrial sectors and the research domain clearly show that fault detection and diagnosis is a very promising niche. In recent years, many techniques have been developed for detecting faults in electric machines; among them stator current-based signal processing techniques mainly for induction motors. This PhD thesis have been therefore focused on an analysis and then a comparison study of advanced signal processing techniques for fault detection and diagnosis in induction machines used in wind turbines. First a state of the art presenting different type of energies (fossils and renewable) allowed to highlight wind energy importance. Then, a brief presentation is given on main faults in induction machine-based wind turbines. This has allowed the introduction of different advanced signal processing techniques for a wind turbine application and therefore has highlighted the main limitations of the already used techniques for the motor application. Knowing the stator current nonstationary nature (wind turbine operation and fault occurrence), it has then be proceeded to test specific techniques such as time-frequency and wavelets, These techniques were then used to build-up a Matlab-Simulink®-based tool devoted to the condition monitoring of a wind turbine induction generator.BREST-BU Droit-Sciences-Sports (290192103) / SudocSudocFranceF

Biosensing Using a Simple Resistor: The Effect of Functionalization on Sensing Devices

Biosensors can play an important role in early disease detection, a reason why they are gaining more attention in the world of biomedicine. Functionalization of the material used in the detector is of a great importance since it maintains the molecule’s structure of interest with minimal changes. We report on sensing BSA molecules, solutions, and concentrations using a functionalized commercial resistor in a simple electric circuit. Our results demonstrate the outstanding utility of functionalization in biosensing devices; while sensing is not possible with a naked resistor, a BSA covered resistor can detect a very low solution concentration around 0.1 fM. A smaller molecule like tryptophan was also used in order to functionalize the resistor. After proving that tryptophan is more effective in covering the resistor before sensing, BSA molecules in other solvent conditions were detected, and a threshold of 1 μM was obtained. This can prove that sensing depends on the choice of the functionalizations of the material used for sensing and on the conformation of the molecule of interest in its solutions. This method of detection may be of great interest in triggering and sensing biological molecules using simple-based devices

Association between vitamin D deficiency and multiple sclerosis- MRI significance: A scoping review

Background/Objective: Multiple Sclerosis is a common demyelinating disease of the central nervous system. Several studies suggested a link between vitamin D deficiency and multiple sclerosis disease activity, which can be evaluated by magnetic resonance imaging. Thereby, the main objective of the following scoping review is to summarize the magnetic resonance imaging findings assessing the probable effects of vitamin D on MS disease activity. Methodology: PRISMA checklist for systematic reviews and meta-analyses was employed to structure this review. Literature was searched for observational and clinical studies tackling the given matter using several search engines including PubMed, CORE, and Embase. Data was extracted in a systematic manner, and the articles meeting the inclusion criteria were quality-assessed by Jadad scale for randomized clinical trials (RCTs) and Newcastle-Ottawa scale for observational studies. Results: A total of 35 articles were included. Twenty-one (60%) studies noted a statistically significant association between vitamin D and Multiple Sclerosis MRI-detected disease activity. MRI-detected features involved lower contrast-enhancing T1 lesions, lower hyperintense T2 lesions, and a decrease in lesions volume. On the other hand, 40% (14 articles) of the articles did not detect any significant effect of vitamin D on Multiple Sclerosis disease activity. Due to the heterogeneity of the studies involved, meta-analysis was not employed in the given review. Discussion/conclusion: There was an abundance in the number of research studies investigating the relationship between vitamin D and Multiple Sclerosis while highlighting the significant role of MRI in assessing the activity of the disease. Numerous studies found that higher serum vitamin D levels are associated with decreased new active cortical and subcortical lesions and lower lesions volume. These findings highlight the importance of imaging modalities in the various aspects of neurological diseases and encourage further research to focus on the preventive effects of vitamin D on MS patients

Evaluation of the accuracy of new modalities in the assessment and classification of lumbar lordosis: A comparison to Cobb's angle measurement

Background: Because of the association of lumbar lordosis with some clinical conditions such as low back pain, the chiropractic field has emphasized the significance of evaluating the lumbar lordotic status, by measuring Cobb's angle, regarded as the radiological gold standard, for the assessment of lumbar lordosis, on lateral radiographs. However, research has shown that this technique has some considerable drawbacks, mostly in terms of low accuracy and high variability between clinicians when compared with other radiological modalities. The main objective was to compare the diagnostic accuracy of newly established radiological measurements with one of Cobb's angle methods, for the characterization of lumbar lordosis status in a sample of Lebanese patients aged 15 and above. Material and methods: This retrospective single-center study consisted of measuring Cobb's L1-S1 and Cobb's L1-L5 angles, along with the novel established measurements which are the derivative and the normalized surface area, on 134 lateral radiographs of the lumbar spine of Lebanese patients aged fifteen years old and above, gotten from the Radiology department at Zahra'a’s Hospital in Beirut, performed by two observers using MATLAB. Inter-rater agreement was assessed by calculating the Intra-class correlation coefficients. Spearman correlation was analyzed between both Cobb's angle methods and with the derivative and normalized area respectively. 54 patients of the sample were diagnosed by two radiologists, according to their LL status. ROC curve analysis was performed to compare the diagnostic accuracy of the four techniques used. Data were analyzed with IBM SPSS Statistics 23.0 (NY, USA); P < 0.05 was considered statistically significant. Results: According to the ROC curve analysis the new methods, which are the derivative and the normalized surface area, displayed lower diagnostic accuracy (AUCderivative = 0.818 and 0.677, AUCsurface area = 0.796 and 0.828) than Cobb's L1-L5 (AUCL1-L5 = 0.924 and 0.929 values) and L1-S1 (AUCL1-S1 = 0.971 and 0.955) angles, in the characterization of hypo and hyperlordotic patients, respectively, in our Lebanese sample consisting of patients aged 15 and above, because of their lower area under the curve's values compared to the traditional Cobb's techniques. The Cobb's L1-S1 has shown to have the highest diagnostic accuracy among the four methods to characterize normal patients from hypo and hyperlordotic ones, by referring to its highest area under the curve's values. However, the sensitivity of Cobb's L1-L5 angle in characterizing hyperlordotic patients was similar to the one of the normalized surface area with a value of 100%.Conclusion: among the four modalities, the new methods didn't show a better diagnostic accuracy compared to the traditional modalities. Cobb's L1-S1 displayed the highest diagnostic accuracy despite its drawbacks. Further prospective studies are needed to validate the cut-offs obtained for Cobb's L1-S1 angle in our sample