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  • 1
    Online Resource
    Online Resource
    An Improved Wavelet Threshold Denoising Method for Health Monitoring Data: A Case Study of the Hong Kong-Zhuhai-Macao Bridge Immersed Tunnel
    MDPI AG ; 2022
    In:  Applied Sciences Vol. 12, No. 13 ( 2022-07-03), p. 6743-
    Details
    In: Applied Sciences, MDPI AG, Vol. 12, No. 13 ( 2022-07-03), p. 6743-
    Abstract: Tunnels generally operate underground or underwater in a complex environment. As a result, the health monitoring system is inevitably affected by various environmental factors, which introduces noise to the system. However, the noise contained in the monitoring sequence may disrupt structural damage identification and health state assessment as the real structural response may be overwhelmed by the noise. To properly eliminate the noise in an objective way, this study proposed an improved wavelet threshold denoising method. Firstly, it adopts a quantitative factor, namely the Sparse Index, to assist the selection of the best wavelet basis in numerous wavelet packages. Then, the decomposition layer and threshold are optimized by a comprehensive evaluation based on a variation coefficient method. At last, the application of the concrete strain health monitoring data of the Hong Kong-Zhuhai-Macao Bridge immersed tunnel verified the effectiveness of the proposed method. It is found that the combination of sym12 and five decomposition layers can obtain the best denoising results within the selected wavelet families and decomposition levels. Moreover, the proposed method achieves good denoising results under different fluctuation levels. Thus, the proposed method is reliable, can solve the problem of optimal parameter selection such as decomposition level and wavelet basis in wavelet denoising, and can be applied in the structural health monitoring of critical infrastructures.
    Type of Medium: Online Resource
    ISSN: 2076-3417
    URL: Article
    DOI: 10.3390/app12136743
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2704225-X
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  • 2
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    Dynamic Warning Method for Structural Health Monitoring Data Based on ARIMA: Case Study of Hong Kong–Zhuhai–Macao Bridge Immersed Tunnel
    MDPI AG ; 2022
    In:  Sensors Vol. 22, No. 16 ( 2022-08-18), p. 6185-
    Details
    In: Sensors, MDPI AG, Vol. 22, No. 16 ( 2022-08-18), p. 6185-
    Abstract: Structural health monitoring (SHM) is gradually replacing traditional manual detection and is becoming a focus of the research devoted to the operation and maintenance of tunnel structures. However, in the face of massive SHM data, the autonomous early warning method is still required to further reduce the burden of manual analysis. Thus, this study proposed a dynamic warning method for SHM data based on ARIMA and applied it to the concrete strain data of the Hong Kong–Zhuhai–Macao Bridge (HZMB) immersed tunnel. First, wavelet threshold denoising was applied to filter noise from the SHM data. Then, the feasibility and accuracy of establishing an ARIMA model were verified, and it was adopted to predict future time series of SHM data. After that, an anomaly detection scheme was proposed based on the dynamic model and dynamic threshold value, which set the confidence interval of detected anomalies based on the statistical characteristics of the historical series. Finally, a hierarchical warning system was defined to classify anomalies according to their detection threshold and enable hierarchical treatments. The illustrative example of the HZMB immersed tunnel verified that a three-level (5.5 σ, 6.5 σ, and 7.5 σ) dynamic warning schematic can give good results of anomalies detection and greatly improves the efficiency of SHM data management of the tunnel.
    Type of Medium: Online Resource
    ISSN: 1424-8220
    URL: Article
    DOI: 10.3390/s22166185
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2052857-7
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  • 3
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    Growth of Pentacene-Doped p-Terphenyl Crystals Using SSVBT and Doping Effects in p-Terphenyl Molecular Crystals
    MDPI AG ; 2022
    In:  Crystals Vol. 13, No. 1 ( 2022-12-20), p. 2-
    Details
    In: Crystals, MDPI AG, Vol. 13, No. 1 ( 2022-12-20), p. 2-
    Abstract: High-quality pentacene-doped p-terphenyl bulk crystals were grown by the selective self-seeding vertical Bridgman technique (SSVBT). The lattice structure and crystal properties of the samples of different doping concentrations and their relations with p-terphenyl single crystals were tested and analyzed. The doping effects of pentacene doping at different concentrations in p-terphenyl molecular crystals are discussed. The powder X-ray diffraction, FTIR, and 1H NMR studies show that no additional peaks (except for p-terphenyl) are observed in the spectra of two doped crystals. The results indicate that guest molecules appear as defects in the form of irregularly oriented molecules which do not significantly change the crystal structures. As the doping concentration increases, the average crystallite size decreases, and the crystallinity declines. The ultraviolet–visible absorption and fluorescence spectra show that with added pentacene molecules, the characteristic peak intensities decrease in the spectra owing to the p-terphenyl molecular transition. Meanwhile, characteristic peaks appear due to the pentacene molecular transition. Moreover, with the increase of doping concentration, the intensities of characteristic peaks of host molecules decrease continuously, and those of guest molecules increase accordingly.
    Type of Medium: Online Resource
    ISSN: 2073-4352
    URL: Article
    DOI: 10.3390/cryst13010002
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2661516-2
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  • 4
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    Integrative Physiological and Transcriptome Analysis Reveals the Mechanism for the Repair of Sub-Lethally Injured Escherichia coli O157:H7 Induced by High Hydrostatic Pressure
    MDPI AG ; 2022
    In:  Foods Vol. 11, No. 15 ( 2022-08-08), p. 2377-
    Details
    In: Foods, MDPI AG, Vol. 11, No. 15 ( 2022-08-08), p. 2377-
    Abstract: The application of high hydrostatic pressure (HHP) technology in the food industry has generated potential safety hazards due to sub-lethally injured (SI) pathogenic bacteria in food products. To address these problems, this study explored the repair mechanisms of HHP-induced SI Escherichia coli O157:H7. First, the repair state of SI E. coli O157:H7 (400 MPa for 5 min) was identified, which was cultured for 2 h (37 °C) in a tryptose soya broth culture medium. We found that the intracellular protein content, adenosine triphosphate (ATP) content, and enzyme activities (superoxide dismutase, catalase, and ATPase) increased, and the morphology was repaired. The transcriptome was analyzed to investigate the molecular mechanisms of SI repair. Using cluster analysis, we identified 437 genes enriched in profile 1 (first down-regulated and then tending to be stable) and 731 genes in profile 2 (up-regulated after an initial down-regulation). KEGG analysis revealed that genes involved in cell membrane biosynthesis, oxidative phosphorylation, ribosome, and aminoacyl-tRNA biosynthesis pathways were enriched in profile 2, whereas cell-wall biosynthesis was enriched in profile 1. These findings provide insights into the repair process of SI E. coli O157:H7 induced by HHP.
    Type of Medium: Online Resource
    ISSN: 2304-8158
    URL: Article
    DOI: 10.3390/foods11152377
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2704223-6
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  • 5
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    Online Resource
    A Novel Pigeon-Inspired Optimization Based MPPT Technique for PV Systems
    MDPI AG ; 2020
    In:  Processes Vol. 8, No. 3 ( 2020-03-20), p. 356-
    Details
    In: Processes, MDPI AG, Vol. 8, No. 3 ( 2020-03-20), p. 356-
    Abstract: The conventional maximum power point tracking (MPPT) method fails in partially shaded conditions, because multiple peaks may appear on the power–voltage characteristic curve. The Pigeon-Inspired Optimization (PIO) algorithm is a new type of meta-heuristic algorithm. Aiming at this situation, this paper proposes a new type of algorithm that combines a new pigeon population algorithm named Parallel and Compact Pigeon-Inspired Optimization (PCPIO) with MPPT, which can solve the problem that MPPT cannot reach the near global maximum power point. This hybrid algorithm is fast, stable, and capable of globally optimizing the maximum power point tracking algorithm. Therefore, the purpose of this article is to study the performance of two optimization techniques. The two algorithms are Particle Swarm Algorithm (PSO) and improved pigeon algorithm. This paper first studies the mechanism of multi-peak output characteristics of photovoltaic arrays in complex environments, and then proposes a multi-peak MPPT algorithm based on a combination of an improved pigeon population algorithm and an incremental conductivity method. The improved pigeon algorithm is used to quickly locate near the maximum power point, and then the variable step size incremental method INC (incremental conductance) is used to accurately locate the maximum power point. A simulation was performed on Matlab/Simulink platform. The results prove that the method can achieve fast and accurate optimization under complex environmental conditions, effectively reduce power oscillations, enhance system stability, and achieve better control results.
    Type of Medium: Online Resource
    ISSN: 2227-9717
    URL: Article
    DOI: 10.3390/pr8030356
    Language: English
    Publisher: MDPI AG
    Publication Date: 2020
    detail.hit.zdb_id: 2720994-5
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  • 6
    Online Resource
    Online Resource
    Preparation of Anti-Aristolochic Acid I Monoclonal Antibody and Development of Chemiluminescent Immunoassay and Carbon Dot-Based Fluoroimmunoassay for Sensitive Detection of Aristolochic Acid I
    MDPI AG ; 2021
    In:  Foods Vol. 10, No. 11 ( 2021-11-01), p. 2647-
    Details
    In: Foods, MDPI AG, Vol. 10, No. 11 ( 2021-11-01), p. 2647-
    Abstract: Aristolochic acid (AA) toxicity has been shown in humans regarding carcinogenesis, nephrotoxicity, and mutagenicity. Monitoring the AA content in drug homologous and healthy foods is necessary for the health of humans. In this study, a monoclonal antibody (mAb) with high sensitivity for aristolochic acid I (AA-I) was prepared. Based on the obtained mAb, a chemiluminescent immunoassay (CLEIA) against AA-I was developed, which showed the 50% decrease in the RLUmax (IC50) value of 1.8 ng/mL and the limit of detection (LOD) of 0.4 ng/mL. Carbon dots with red emission at 620 nm, namely rCDs, were synthesized and employed in conventional indirect competitive enzyme-linked immunosorbent assay (icELISA) to improve the assay sensitivity of a fluoroimmunoassay (FIA). Oxidized 3,3′′,5,5′′-tetramethylbenzidine dihydrochloride (oxTMB) can quench the emission of the rCDs through the inner-filter effect; therefore, the fluorescence intensity of rCDs can be regulated by the concentration of mAb. As a result, the assay sensitivity of FIA was improved by five-fold compared to CLEIA. A good relationship between the results of the proposed assays and the standard ultra-high performance liquid chromatography-triple quadrupole mass spectrometer (UPLC-QQQ-MS/MS) of real samples indicated good accuracy and practicability of CLEIA and FIA.
    Type of Medium: Online Resource
    ISSN: 2304-8158
    URL: Article
    DOI: 10.3390/foods10112647
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2704223-6
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  • 7
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    Experimental Study on Spray Cooling Heat Transfer of LN2 for a Large Area
    MDPI AG ; 2023
    In:  Energies Vol. 16, No. 9 ( 2023-05-03), p. 3877-
    Details
    In: Energies, MDPI AG, Vol. 16, No. 9 ( 2023-05-03), p. 3877-
    Abstract: Spray cooling has been considered one of the most promising thermal control methods of high-heat flux devices. Most of the spray cooling research focuses on electronic components as the main application object to achieve higher heat dissipation heat flow in ambient temperature regions for small areas. Water is the most common cooling medium. This paper investigates the application of spray cooling thermal control over large areas. In this study, the heat-transfer characteristics of liquid nitrogen (LN2) for large areas was investigated by conducting experiments. The test surface is 500 mm × 500 mm, which was cooled by a nine-nozzle array. The spray nozzles used in the experiment were conical nozzles with an orifice diameter of 1.6 mm, a spray angle of 120°, and a spray height of 42 mm. Liquid nitrogen was forcefully ejected from nozzles by the high pressure of a liquid storage tank to cool the test surface. According to the cooled surfaces, spray directions, and spray pressures, three groups of experiments were conducted. The results showed that the smooth flat surface has the best heat-transfer performance in three kinds of surface structures, which are macro surface, porous surface, and smooth flat surface. The heat-transfer coefficient varied by ±20% with different spray directions, and the surface heat-transfer coefficient increased linearly with increasing spray pressure. Most of the spray cooling research focuses on heat dissipation in the ambient temperature region for equipment over small areas. The results can benefit thermal control application in various fields. The research in this paper can provide a reference for the application of large-area spray cooling, and the application areas mainly include metal manufacturing processing cooling, aircraft skin infrared radiation characteristics modulation, and laser weapon equipment cooling.
    Type of Medium: Online Resource
    ISSN: 1996-1073
    URL: Article
    DOI: 10.3390/en16093877
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2437446-5
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  • 8
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    Improved Binary Grasshopper Optimization Algorithm for Feature Selection Problem
    MDPI AG ; 2022
    In:  Entropy Vol. 24, No. 6 ( 2022-05-31), p. 777-
    Details
    In: Entropy, MDPI AG, Vol. 24, No. 6 ( 2022-05-31), p. 777-
    Abstract: The migration and predation of grasshoppers inspire the grasshopper optimization algorithm (GOA). It can be applied to practical problems. The binary grasshopper optimization algorithm (BGOA) is used for binary problems. To improve the algorithm’s exploration capability and the solution’s quality, this paper modifies the step size in BGOA. The step size is expanded and three new transfer functions are proposed based on the improvement. To demonstrate the availability of the algorithm, a comparative experiment with BGOA, particle swarm optimization (PSO), and binary gray wolf optimizer (BGWO) is conducted. The improved algorithm is tested on 23 benchmark test functions. Wilcoxon rank-sum and Friedman tests are used to verify the algorithm’s validity. The results indicate that the optimized algorithm is significantly more excellent than others in most functions. In the aspect of the application, this paper selects 23 datasets of UCI for feature selection implementation. The improved algorithm yields higher accuracy and fewer features.
    Type of Medium: Online Resource
    ISSN: 1099-4300
    URL: Article
    DOI: 10.3390/e24060777
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2014734-X
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  • 9
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    Genome-Wide Identification of the MYB Gene Family in Cymbidiumensifolium and Its Expression Analysis in Different Flower Colors
    MDPI AG ; 2021
    In:  International Journal of Molecular Sciences Vol. 22, No. 24 ( 2021-12-09), p. 13245-
    Details
    In: International Journal of Molecular Sciences, MDPI AG, Vol. 22, No. 24 ( 2021-12-09), p. 13245-
    Abstract: MYB transcription factors of plants play important roles in flavonoid synthesis, aroma regulation, floral organ morphogenesis, and responses to biotic and abiotic stresses. Cymbidium ensifolium is a perennial herbaceous plant belonging to Orchidaceae, with special flower colors and high ornamental value. In this study, a total of 136 CeMYB transcription factors were identified from the genome of C. ensifolium, including 27 1R-MYBs, 102 R2R3-MYBs, 2 3R-MYBs, 2 4R-MYBs, and 3 atypical MYBs. Through phylogenetic analysis in combination with MYB in Arabidopsis thaliana, 20 clusters were obtained, indicating that these CeMYBs may have a variety of biological functions. The 136 CeMYBs were distributed on 18 chromosomes, and the conserved domain analysis showed that they harbored typical amino acid sequence repeats. The motif prediction revealed that multiple conserved elements were mostly located in the N-terminal of CeMYBs, suggesting their functions to be relatively conserved. CeMYBs harbored introns ranging from 0 to 13 and contained a large number of stress- and hormone-responsive cis-acting elements in the promoter regions. The subcellular localization prediction demonstrated that most of CeMYBs were positioned in the nucleus. The analysis of the CeMYBs expression based on transcriptome data showed that CeMYB52, and CeMYB104 of the S6 subfamily may be the key genes leading to flower color variation. The results lay a foundation for the study of MYB transcription factors of C. ensifolium and provide valuable information for further investigations of the potential function of MYB genes in the process of anthocyanin biosynthesis.
    Type of Medium: Online Resource
    ISSN: 1422-0067
    URL: Article
    DOI: 10.3390/ijms222413245
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2019364-6
    SSG: 12
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  • 10
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    A Variable-Weather-Parameter MPPT Method Based on Equation Solution for Photovoltaic System with DC Bus
    MDPI AG ; 2022
    In:  Energies Vol. 15, No. 18 ( 2022-09-13), p. 6671-
    Details
    In: Energies, MDPI AG, Vol. 15, No. 18 ( 2022-09-13), p. 6671-
    Abstract: The control signals of the variable-weather-parameter (VWP) methods need to be calculated by the real-time measured data of the irradiance and temperature (I & T) sensors, which leads to the high hardware cost of the sensors. To solve this problem, the PV system with a DC bus is selected as the research subject and a novel maximum power point tracking (MPPT) method is proposed. It is named the VWP MPPT method based on the equation solution (ES-VWP method). Its control signal is directly calculated by the solution of an established equation set rather than data measured by the I & T sensors. This equation set consists of two integrated mathematical equations, which represent two different operating points of the PV system. Meanwhile, when the bus voltage is varying or unknown, a calculation method that can estimate the real-time value of the DC bus voltage is proposed. In addition, an implementation method corresponding to the ES-VWP method is also designed. Finally, some simulation experiments are carried out to verify the availability and feasibility of the ES-VWP method. Meanwhile, some simulation experiments show that the error of the equation solution is less than 0.0001. In addition, some simulation experiments illustrate that the MPPT settling times of the ES-VWP method are always less than one-tenth of the P & O method (or one-sixth of the FLC method). Compared with the existing VWP methods, it can be implemented without the use of I & T sensors or external I & T data. Meanwhile, compared with other existing MPPT methods, its better MPPT rapidity originating from the advantage of the VWP methods is inherited. This work is the first attempt to design a novel MPPT method by obtaining the real-time equation solutions of Voc and Isc. Meanwhile, this work is also the first attempt to solve the real-time equation of Vbus by the solved Voc and Isc. In addition, this work is also the first attempt to design an implementation method for establishing an equation set by sampling two operating points of a PV system at the same time.
    Type of Medium: Online Resource
    ISSN: 1996-1073
    URL: Article
    DOI: 10.3390/en15186671
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2437446-5
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