Theoretical and Experimental Studies of Micro-Surface Crack Detections Based on BOTDA

Micro-surface crack detection is important for the health monitoring of civil structures. The present literature review shows that micro-surface cracks can be detected by the Brillouin scattering process in optical fibers. However, the existing reports focus on experiment research. The comparison between theory and experiment for Brillouin-scattering-based optical sensors is rarely reported. In this paper, a distributed optical fiber sensor for monitoring micro-surface cracks is presented and demonstrated. In the simulation, by using finite element methods, an assemblage of a three-dimensional beam model for Brillouin optical time domain analysis (BOTDA) was built. The change in Brillouin frequency (distributed strain) as a function of different cracks was numerically investigated. Simulation results indicate that the amplitudes of the Brillouin peak increase from 27 με to 140 με when the crack opening displacement (COD) is enlarged from 0.002 mm to 0.009 mm. The experiment program was designed to evaluate the cracks in a beam with the length of 15 m. Experimental results indicate that it is possible to detect the COD in the length of 0.002~0.009 mm, which is consistent with the simulation data. The limitations of the proposed sensing method are discussed, and the future research direction is prospected

Novel Fuzzy Logic Controls to Enhance Dynamic Frequency Control and Pitch Angle Regulation in Variable-Speed Wind Turbines

This study introduced a novel control approach based on fuzzy logic control (FLC) to enhance the frequency regulation capacity of variable-speed wind turbines (VSWTs). The proposed method integrates FLC within droop and inertia control loops. Real-time measurements of the system frequency and the rate of change of frequency (ROCOF) serve as inputs to the FLC, enabling the method to improve the frequency response by VSWTs. In addition, the method employs FLC for pitch angle frequency control, optimizing reserve power for frequency regulation under varying wind speed levels. The innovative aspect of this study lies in the simultaneous application of FLC to pitch angle frequency control and droop/inertia control, leading to the enhanced frequency regulation capability of VSWTs and smoother operation across a range of wind speeds. Compared with traditional methods, the proposed approach provides a comprehensive and effective solution to the challenges associated with frequency regulation in VSWTs. Through simulations across different wind speed scenarios, the proposed control method demonstrated the best performance among various mature methods, highlighting the efficacy of the proposed method on the frequency regulation of VSWTs under different wind speeds. This study’s findings highlight the potential of the proposed FLC-based method to optimize frequency regulation and contribute to more reliable and efficient wind energy systems

Effect of magnetic field annealing on soft magnetic properties of Co71Fe2Si14-xB9+xMn4 amorphous alloys with low permeability

The effect of transverse magnetic field annealing (TFA) on soft magnetic properties of Co71Fe2Si14-xB9+xMn4 amorphous alloys was investigated with the aim of reducing effective permeability (μe). It was revealed that the increasing B content improved thermal stability, increased saturation magnetic flux density (Bs) of as-quenched alloys, while the samples exhibited a slightly larger coercivity (Hc) when the atom percentages of Si and B were similar. Permeability decreased dramatically after TFA. The decrease of permeability mainly depended on annealing temperature and magnetic field intensity. Besides, flat hysteresis loops were obtained after TFA, Lorentz micrograph observation revealed the TFA sample exhibited denser magnetic domain walls, which confirmed it was more difficult to be saturated. The Co71Fe2Si9B14Mn4 alloy was successful prepared with low μe of 3020, low Hc of 1.7 A/m and high resistance to DC bias 6 times that of as-quenched alloy at the DC field of 300 A/m

Resolution-Based Analysis for Optimizing Subaperture Measurements in Circular SAR Imaging

Circular geometries are often encountered in nondestructive testing and evaluation applications. Circular synthetic aperture radar imaging technique, capable of producing high-resolution images, has great utility for this purpose. However, in many such applications, scanning only a portion of the circular geometry (i.e., scanning domain), called the subaperture, may only be possible or sufficient for a particular inspection need. Consequently, in subaperture imaging, for an imaging aspect angle and aspect angle measurement interval, we must determine the expected image resolution. In this paper, for an arbitrary area of interest, we analyze the image spatial resolution obtained from a generally defined aspect angle and aspect angle measurement interval. Using resolution as the criteria, we use this method to determine the boundary between small and large subapertures, which also show to produce markedly different range and cross-range resolutions as a function of aspect angle and aspect angle measurement interval. Moreover, the optimum aspect angle and aspect angle measurement interval for this fixed area of interest are defined based on these analyses. Finally, the results of these analyses and images obtained from simulations are compared and corroborated with relevant experimental results at X-band (8.2-12.4 GHz)

Profiling of mouse macrophage lipidome using direct infusion shotgun mass spectrometry.

Immune cells, such as macrophages, reprogram their lipid metabolism in response to the activation of pattern recognition receptors (e.g., TLRs, NLRs) and cytokine receptors (e.g., interferons, interleukins). Profiling these changes can be achieved with shotgun mass spectrometry. This protocol provides step-by-step instructions on the generation and stimulation of bone marrow-derived macrophages (BMDMs), sample collection, and lipid extraction for profiling the macrophage lipidome. For complete details on the use and execution of this protocol, please refer to Hsieh et al. (2020)

Probabilistic short-term power load forecasting based on B-SCN

Grid management and power dispatching rely on accurate short-term power load prediction. Different algorithms have been constantly developed and tested to improve forecast precision. However, these forecasts are constrained by a number of uncertain factors, which are caused by dynamic environment, the nonlinearity and stochasticity of power demand. To obtain more accurate load forecasting value and quantify the uncertainty effectively, this research proposes a boosting stochastic configuration network(B-SCN) based probabilistic forecasting method. First, correlation analysis is taken in multidimensional input parameters. Second, an adaptive B-SCN network architecture is proposed to construct the prediction model and improve the stability of model outputs significantly. The probabilistic forecasting is then used to actualize the model’s uncertainty evaluation by creating the confidence intervals using the Gaussian process. Consequently, experimental results reveal that the proposed boosting-SCN prediction model achieves superior forecasting accuracy than the single SCN model and other commonly used forecasting models. The probabilistic forecasting can efficiently obtain the uncertainties in power load data and provide support for system operation

Time-Reversal SAR Imaging for Nondestructive Testing of Circular and Cylindrical Multi-Layered Dielectric Structures

In this paper, a synthetic aperture radar (SAR) approach, for imaging internal structures of generally lossy layered dielectric cylindrical objects, is presented. This method which properly accounts for different transmission and refraction path at each boundary between different layers, produces a properly focused image of embedded targets. This approach is also capable of addressing imaging needs for asymmetrical multi-layered cylindrical bodies. Consequently, this approach overcomes the limitation associated with the conventional methodology, in which free-space propagation is assumed. The calculation method of angular sampling criterion for circular and cylindrical SAR (i.e., circumferential and in height) are also presented. Electromagnetic simulations are performed on a three-layer cylindrical object, symmetrical and asymmetrical, with embedded targets to validate the approach. In addition, representative measurements are conducted at X-band (8.2-12.4 GHz) demonstrating the effectiveness of the approach for practical nondestructive evaluation applications

Transcriptome Analysis Clarified Genes Involved in Betalain Biosynthesis in the Fruit of Red Pitayas (<i>Hylocereus costaricensis</i>)

The red flesh trait gives red pitayas more healthful components and a higher price, while the genetic mechanism behind this trait is unknown. In this manuscript, transcriptome analysis was employed to discover the genetic differences between white and red flesh in pitayas. A total of 27.99 Gb clean data were obtained for four samples. Unigenes, 79,049 in number, were generated with an average length of 1333 bp, and 52,618 Unigenes were annotated. Compared with white flesh, the expression of 10,215 Unigenes was up-regulated, and 4853 Unigenes were down-regulated in red flesh. The metabolic pathways accounted for 64.6% of all differentially expressed Unigenes in KEGG pathways. The group with high betalain content in red flesh and all structural genes, related to betalain biosynthesis, had a higher expression in red flesh than white flesh. The expression of the key gene, tyrosine hydroxylase CYP76AD1, was up-regulated 245.08 times, while 4,5-DOPA dioxygenase DODA was up-regulated 6.46 times. Moreover, the special isomers CYP76AD1&#945; and DODA&#945; were only expressed in red flesh. The competitive anthocyanin biosynthesis pathway had a lower expression in red flesh. Two MYB transcription factors were of the same branch as BvMYB1, regulating betalain biosynthesis in beet, and those transcription factors had expression differences in two kinds of pitayas, which indicated that they should be candidate genes controlling betalain accumulation in red pitayas. This research would benefit from identifying the major gene controlling red flesh trait and breed new cultivars with the red flesh trait. Future research should aim to prove the role of each candidate gene in betalain biosynthesis in red pitayas