Singular spectral analysis of ill-known signals and its application to predictive maintenance of windmills with SCADA records

A generalization of the singular spectral analysis (SSA) technique to ill-defined data is introduced in this paper. The proposed algorithm achieves tight estimates of the energy of irregular or aperiodic oscillations from records of interval or fuzzy-valued signals. Fuzzy signals are given a possibilistic interpretation as families of nested confidence intervals. In this context, some types of Supervisory Control And Data Analysis (SCADA) records, where the minimum, mean and maximum values of the signal between two scans are logged, are regarded as fuzzy constrains of the values of the sampled signal. The generalized SSA of these records produces a set of interval-valued or fuzzy coefficients, that bound the spectral transform of the SCADA data. Furthermore, these bounds are compared to the expected energy of AR(1) red noise, and the irrelevant components are discarded. This comparison is accomplished using statistical tests for low quality data, that are in turn consistent with the possibilistic interpretation of a fuzzy signal mentioned before. Generalized SSA has been applied to solve a real world problem, with SCADA data taken from 40 turbines in a Spanish wind farm. It was found that certain oscillations in the pressure at the hydraulic circuit of the tip brakes are correlated to long term damages in the windmill gear, showing that this new technique is useful as a failure indicator in the predictive maintenance of windmills.     

Cover Image,Volume 98, Issue 10

The cover image, by Vessela Kancheva et al., is based on the Research Article Protective effects of new antioxidant compositions of 4‐methylcoumarins andrelated compounds with DL‐α‐tocopherol and L‐ascorbic acid, DOI: 10.1002/jsfa.8892 .

     

Supplementation with Cashew Nut and Cottonseed Meal to Modify Fatty Acid Content in Lamb Meat

This study evaluates the effect of cashew nut meal (CNM), whole cottonseed (WCS), and calcium salts of long‐chain fatty acids (Ca‐LCFA) on the fatty acid profiles of meat from hair lambs. Thirty‐five 60‐d‐old, male, noncastrated Santa Ines lambs with an initial average body weight of 13.00 ± 1.80 kg were used in a randomized complete‐block design with 7 blocks and 5 treatments. The experimental treatments consisted of a control diet (CON) without supplemental lipids and 4 test diets with different lipid supplements that were selected according to the degree of protection from ruminal hydrogenation and their polyunsaturated fatty acid richness. The tests diets included the following modifications: supplementation with WCS, supplementation with CNM, supplementation with both cottonseed and CNM (CSCNM), and supplementation with Ca‐LCFA. The C18:1n9c content was highest in the meat of the animals fed the CNM diet (42.00%). The meat from lambs fed the WCS and Ca‐LCFA diets had higher C18:0 contents (25.23 and 22.80%, respectively). The C16:1 content was higher in the meat from the animals fed the CNM and CON diets (1.54 and 1.49%, respectively). C18:2c9t11 concentration was higher in the meat from the animals fed the Ca‐LCFA and CNM diets. The estimated enzyme activity of Δ9‐desaturase C18 was highest in the muscles of the lambs fed the CON, CNM, and CSCNM diets. The use of cashew nuts in the diet resulted in an increase in the C18:2c9t11 content of the lamb meat, which improved the nutritional characteristics of the fat.     

Determination of biogenic amines in wine by thin-layer chromatography/densitometry

Biogenic amines are small-molecular-weight organic bases that can be encountered in all fermented foods, including wine. Ingestion of wine containing biogenic amines, and especially histamine, can result in health nuisances. HPLC is the analytical technique most often employed in the determination of biogenic amines in wine but HPLC-based methods are expensive and time-consuming. A new method, based upon amine dansylation and TLC/densitometry, was developed and validated. This allowed for the determination of histamine, tyramine, putrescine and cadaverine in wine at concentrations between 1 and 20mg/L. Analytical performances adequately complied with the needs of routine wine analysis, moreover the method was high-throughput and inexpensive. A simpler, semi-quantitative version of the method, based on visual evaluation of spot intensity, was also developed.     

The volatile compounds in lamb fat are affected by the time of grazing

This study was designed to assess whether different grazing managements affect the appearance of organic volatile compounds (VOC) in lamb fat. Forty-two lambs were divided into four groups: 9 lambs were restricted in stall and fed concentrate (S group); 12 lambs grazed from 9 am to 5 pm (8 h group); 10 lambs grazed from 9 am to 1 pm (4hAM group) and 11 lambs grazed from 1 pm to 5 pm (4hPM group). After 72 days on feed the animals were slaughtered and the perirenal fat subjected to SPME-GC/MS analysis of VOC; the data were analyzed by stepwise discriminant analysis. The 6-methyl-2-heptanone and furanone, 2,5-dimethyl, 4-hydroxy-3(2H) allowed discrimination between the 4hAM and the 4hPM animals. These are the first results indicating that the time of the day in which the animals are allowed to graze affects the appearance of VOC in lamb fat.     

Carotenoid, colour and reflectance measurements in bovine adipose tissue to discriminate between beef from different feeding systems

Our hypothesis was that carotenoids in bovine subcutaneous adipose tissue (SAT) together with colour and reflectance spectra could be used to differentiate between beef production systems based on grass, concentrates or combinations thereof. SAT was sampled from the carcasses of heifers fed pasture (P), a barley-based concentrate (C), silage followed by pasture (SiP) or silage followed by pasture with concentrate (SiPC). β-carotene in the SAT from the C group (0.09 μg g(-1)) was lower (P<0.05) than that from the P (0.54 μg g(-1)), SiP (0.49 μg g(-1)) and SiPC (0.49 μg g(-1)) groups. Lutein in the SAT differed (P<0.05) between all groups with 0.13, 0.10, 0.08 and 0.04 μg g(-1) for the P, SiP, SiPC and C groups, respectively. Principal component analysis of the carotenoid data, SAT colour variables ['L', 'a', 'b', 'C', 'H'] and the reflectance data made it possible to distinguish between the animals fed a barley-based concentrate diet and the animals fed pasture-based diets, but not between different pasture-based groups.