Search

Incipient faults on blade load sensors can impede the sound performance of a wind turbine, leading to increasing loads over time and severe blade degradation. As such, knowledge of the blade load sensors’ health is essential for ensuring effective load reduction by means of individual pitch control. This paper presents a condition monitoring strategy for the blade load sensors based on estimation of the loads acting on the rotor blades in the full-load region. Fault detection is achieved via appropriate residual generators, the statistical properties of which are used to design change detectors robust against measurement noise and wind field stochasticity. Specifically, a Generalized Likelihood Ratio Test for the t-LocationScale distribution is developed for ensuring robust detection of sensor blade faults. The proposed method is evaluated in a high-fidelity simulator under non-uniform wind scenarios. The simulation results show that detection of multiplicative faults on the blade load sensors is achieved even in absence of knowledge of the local wind speed.

Studies have shown that medical devices comprising strontium contribute to bone healing and osseointegration. The aim of this study was to evaluate the in vivo performance of surface‐functionalized implants (Ti‐Sr‐O) showing predictable release characteristics of strontium and compare it to performance a commercially available fluoride‐modified surface. Ti‐Sr‐O functionalized, fluoride‐modified,  Grade 4 titanium implants were inserted in the femoral condyle of adult male New Zealand white rabbits. Atomic absorption spectrometry (AAS) was utilized to monitor strontium blood serum levels. Two weeks after insertion, histomorphometric evaluation was performed with respect to bone‐to‐implant contact (BIC%) and bone formation (BF%) using defined regions of interest. Mean values for BIC% showed a comparable degree of osseointegration for Ti‐Sr‐O and the fluoride‐modified surface, while BF% revealed a significant difference in increased BF with Ti‐Sr‐O. AAS measurements did not indicate any influence of the Ti‐Sr‐O modified implants on the strontium blood serum concentrations. Within the limitations of this study, it was shown that the Ti‐Sr‐O coating, with sustained release characteristics of strontium, enhanced bone apposition and, thus, could find practical applications, e.g., within the field of medical implantology.

Observations by the Emirates eXploration Imager (EXI) on‐board the Emirates Mars Mission are used to characterize the diurnal, seasonal, and spatial behavior of aphelion cloud belt during Mars Year 36 LS∼ 30°–190°. Building from previous work with the Mars Color Imager (MARCI) onboard the Mars Reconnaissance Orbiter, we retrieve water ice extinction optical depth (τice) with an uncertainty ±0.0232 (excluding particle size effects). We connect EXI and MARCI using radiance and τice. Zonal and meridional diurnal trends are analyzed over 6–18 hr Local True Solar Time. The retrievals show large morning‐evening asymmetries about a minimum near 12 hr. The latitudinal distributions in early morning are extensive and particularly striking near mid‐summer. Comparisons to the Mars Planetary Climate Model show reasonable agreement with basic diurnal behavior, but noticeable departures include too much water ice in early morning, the general latitudinal extent, and behavior at smaller scales like the volcanoes and other topographically distinct features. Water ice clouds have important roles in the Martian atmosphere because they can influence weather and act as probes of important weather and climate processes. Using the camera on‐board the Emirates Mars Mission, water ice clouds are studied for the first time throughout the Martian day and year at scales of 10–20 km around the planet. We study a key cloud structure called the aphelion cloud belt (ACB) that encircles the planet at low latitudes during the northern hemisphere spring and summer seasons. Using the camera images from this period, we examine how the ACB structure changes from morning through evening and throughout these two seasons. We developed a computer program that converts the brightness of a pixel into a measure of the cloud thickness. We find that the ACB clouds are much thicker and wide‐spread in the early morning compared to other times of day; and are much more extant across the planet in the morning, particularly in mid‐summer. We also compare to weather prediction programs and find important differences that will help scientists improve Mars weather forecasts for future research and missions. The Emirates eXploration Imager is used to retrieve ice extinction optical depth in Mars Year 36 during solar longitudes 30–190°Diurnal trends of the aphelion cloud belt are examined between 6 and 18 hr using both zonal and meridional maps, revealing new behaviorComparisons to the Mars Planetary Climate Model show reasonable agreement with broad structure, but important differences are noted The Emirates eXploration Imager is used to retrieve ice extinction optical depth in Mars Year 36 during solar longitudes 30–190° Diurnal trends of the aphelion cloud belt are examined between 6 and 18 hr using both zonal and meridional maps, revealing new behavior Comparisons to the Mars Planetary Climate Model show reasonable agreement with broad structure, but important differences are noted

The fuel cell technologies are advancing and maturing for commercial markets. However proper diagnostic tools needs to be developed in order to insure reliability and durability of fuel cell systems. This paper presents a design of a data driven method to detect CO content in the anode gas of a high temperature fuel cell. In this work the fuel cell characterization is based on an experimental equivalent electrical circuit, where model parameters are mapped as a function of the load current. The designed general likelihood ratio test detection scheme detects whether a equivalent electrical circuit parameter differ from the non-faulty operation. It is proven that the general likelihood ratio test detection scheme, with a very low probability of false alarm, can detect CO content in the anode gas of the fuel cell.