Maintenance Optimization and Inspection Planning of Wind Energy Assets: Models, Methods and Strategies

Designing cost-effective inspection and maintenance programmes for wind energy farms is a complex task involving a high degree of uncertainty due to diversity of assets and their corresponding damage mechanisms and failure modes, weather-dependent transport conditions, unpredictable spare parts demand, insufficient space or poor accessibility for maintenance and repair, limited availability of resources in terms of equipment and skilled manpower, etc. In recent years, maintenance optimization has attracted the attention of many researchers and practitioners from various sectors of the wind energy industry, including manufacturers, component suppliers, maintenance contractors and others. In this paper, we propose a conceptual classification framework for the available literature on maintenance policy optimization and inspection planning of wind energy systems and structures (turbines, foundations, power cables and electrical substations). The developed framework addresses a wide range of theoretical and practical issues, including the models, methods, and the strategies employed to optimise maintenance decisions and inspection procedures in wind farms. The literature published to date on the subject of this article is critically reviewed and several research gaps are identified. Moreover, the available studies are systematically classified using different criteria and some research directions of potential interest to operational researchers are highlighted

Control of Driver Whole-Body Vibration Ride Comfort in Agricultural Tractor

Abstract: For today vehicles, ride comfort and dynamic control, are crucial criteria for customers and also for the selection of an appropriate vehicle. Tractors as vehicles are exposed to random vibrations caused by unevenness of road or soil profile, moving elements within the tractor or implements, while setting on a rigid seat without a backrest.  Whole-body vibration transmission influences comfort, performance, and long-term health of the operator. This current study is to evaluate and controlled an agricultural tractor whole-body vibration comfort efficiency, which constitutes one aspect of the physical environment that can cause discomfort to operators, based on standard mathematical formulae and frequency analyses. A gravel road texture was selected and used. To assess vibrations transmitted to the operator, vibration dose values, kurtosis, international road roughness index and power spectral densities of the tractor (seat and floor) recorded signals were evaluated. Seat Effective Amplitude Transmissibility values based on the tractor seat pan vibration dose value (controlled and uncontrolled) outputs in the three-direction lateral, longitudinal and vertical) qualify vibration comfort efficiency. Tri-axial accelerometers were usually mounted on the tractor seat pan and floor. Data are frequency weighted in order to model the human response to vibration in that location and direction

Tire and Engine Sources Contribution to Vehicle Interior Noise and Vibration Exposure Levels

The main objective of the research presented in this paper is to enhance driver-passengers Comfort of a vehicle that in turn leads to better vehicle safety and stability. The focus was put on studying the interior vibration and noise contributions originated from tire-road and engine-transmission subsystems, due to their significant impact on the dynamic performance of the vehicle. The noise and vibration measurements were recorded at the driver’s head position and on the driver legs room. Furthermore, the influence of different tire types and road surface textures on the vehicle interior noise and vibration were considered. The results indicate that the widely used conventional engine mounts and tires in commercial vehicles cannot fulfill the conflicting requirements for the best isolation concerning both road surface and engine-transmission induced excitations. The values of driver’s head position sound pressure level and floor vibration acceleration broadband averages originate for engine-transmission are lower than that for tire-road interaction. Furthermore, the values of RMS, crest factor, kurtosis and IRI for the vehicle waveform were estimated for vehicle speeds, tire types and road surface textures. Moreover, the percentage contribution for both interior noise and vibration originated from tire-road interaction is higher than the one from vehicle engine-transmission system in all the vehicle speed range, tire type and road surface texture considered

Vehicle gearbox fault diagnosis using noise measurements

Noise measurement is one of the technologies for health monitoring and diagnosis of rotating machines such as gearboxes. Although, significant research has been undertaken in understanding the potential of noise measurement in monitoring gearboxes, this has been solely applied on any types of gears (spur, helical, etc.). The condition monitoring of a lab-scale, single stage, gearbox, represents the real vehicle's gearbox, using non-destructive inspection methodology and the processing of the acquired waveform with advanced signal processing techniques is the aim of the present work. Acoustic emission was utilized for this purpose. The experimental setup and the instrumentation are present in detail. Emphasis is given on the signal processing of the acquired noise measurement signal in order to extract conventional as well as novel parameters of potential diagnostic value from the monitoring waveform. The evolution of selected parameters/features versus test time is considered, evaluated and the parameters with most interesting diagnostic behavior are highlighted. The present work also describes the results concluded by long term (~6.0 h) experiments to a defected gear system, with a transverse cuts ranged from 0.75 to 3.0 mm to simulate the artificial tooth crack. Different parameters, related to the analysis of the recording signals coming from acoustic emission are presented and their diagnostic value is discussed for the development of a condition monitoring system

Assessment of Osteogenic Material with and Without Low Intensity Laser Activation in Acceleration of Healing Intra-bony Defects

The purpose of this study was to evaluate the efficacy of a new material with or without Low intensity laser treatment in accelerating bone formation of an apical radiolucency through a surgical procedure. In this study a total of 30 upper anterior maxillary teeth with periapical lesions ranging from 5-8mm in diameter. Patients were divided randomly into three groups: Group A: Curettage and Filling osseous defect with Nanobone graft only (n=10).Group B: Curettage and treating the Osseous defect with Laser only (n=10).Group C: Curettage and Filling Osseous defect with Nanobone graft and treating the defect with Low intenisty laser (n=10). Cone beam was taken to determine the presence of periapical radiolucency and its approximate sizes, all patients were followed up using CBCT at 3, 6 and 12 months interval for evaluation of the bone density and size of the radiolucent area. Results: The results of our present study in case of panoramic view (CBCT), it was found that group A (NBG) and C(L+NBG) showed increase in the grey scale value(bone density), while the third group B(LG) had shown lowest grey scale value, on the other hand, in case of cross-section view (CBCT), it was found that group C(L+NBG) had shown the highest grey scale value regarding the other two groups (NBG, LG). Conclusion: The use of Nano-bone graft and Low intensity laser technique in endodontic surgery is considered an optimum choice, as they both accelerate bone and tissue healing, the use of Low intensity laser decrease the post- operative pain and symptoms, the use of CBCT is considered the only effective method for measuring the bone density or the grey value