•Discover competitive cracking behavior in accelerated CCF failure for turbine blades.•Find crack initiation change from slip planes to metallic pores and carbides, to oxides.•Reveal damage ...mechanisms in acceleration states by microstructural dominant features.•The source of cracking transition from transgranular to intergranular mode is the detected behavior.•Provide a promising mechanism insight for CCF estimation and acceleration test.
The cracking behavior and microscopic mechanism of K403 superalloy turbine blade are investigated respecting the Combined high and low Cycle Fatigue (CCF) with four acceleration states. It concludes that: (1) the crack initiation sites transform from slip planes inside alloy matrix to subsurface pores and carbides, then to oxides outside surface with increasing loads; (2) the behavior in (1) is attributed to the competition and alliance of different microstructural factors and the interaction of the factors with grain boundaries; (3) hereinto, the role shift of high cycle fatigue in CCF causes the transformation of transgranular to intergranular cracking mode.
Accurate and fast identification of vibration signals detected based on the phase-sensitive optical time-domain reflectometer (Φ-OTDR) is crucial in reducing the false-alarm rate of the long-distance ...distributed vibration warning system. This study proposes a computer vision-based Φ-OTDR multi-vibration events detection method in real-time, which can effectively detect perimeter intrusion events and reduce personnel patrol costs. Pulse accumulation, pulse cancellers, median filter, and pseudo-color processing are employed for vibration signal feature enhancement to generate vibration spatio-temporal images and form a customized dataset. This dataset is used to train and evaluate an improved YOLO-A30 based on the YOLO target detection meta-architecture to improve system performance. Experiments show that using this method to process 8069 vibration data images generated from 5 abnormal vibration activities for two types of fiber optic laying scenarios, buried underground or hung on razor barbed wire at the perimeter of high-speed rail, the system mAP@.5 is 99.5%, 555 frames per second (FPS), and can detect a theoretical maximum distance of 135.1 km per second. It can quickly and effectively identify abnormal vibration activities, reduce the false-alarm rate of the system for long-distance multi-vibration along high-speed rail lines, and significantly reduce the computational cost while maintaining accuracy.
Two floating treatment wetlands (FTWs) in experimental tanks were compared in terms of their effectiveness on removing nutrients. The results showed that the FTWs were dominated by emergent wetland ...plants and were constructed to remove nutrients from simulated urban stormwater. Iris pseudacorus and Thalia dealbata wetland systems were effective in reducing the nutrient. T. dealbata FTWs showed higher nutrient removal performance than I. pseudacorus FTWs. Nitrogen (N) and phosphorous (P) removal rates in water by T. dealbata FTWs were 3.95 ± 0.19 and 0.15 ± 0.01 g/m
/day, respectively. For I. pseudacorus FTWs, the TN and TP removal rates were 3.07 ± 0.15 and 0.14 ± 0.01 g/m
/day, respectively. The maximum absolute growth rate for T. dealbata corresponded directly with the maximum mean nutrient removal efficiency during the 5th stage. At harvest, N and P uptak of T. dealbata was 23.354 ± 1.366 g and 1.489 ± 0.077 g per plant, respectively, approximate twice as high as by I. pseudacorus.
•Biogas upgrading and digestate nutrient reduction could be simultaneously achieved.•Red was the optimal light for biogas upgrading and digestate nutrient reduction.•The optimal light intensity range ...was between 1200 and 1600μmolm−2s−1.•The CH4 content attained the highest value of 92.74±3.56% (v/v).
Biogas is a well-known, primary renewable energy source, but its utilizations are possible only after upgrading. The microalgae-based bag photo-bioreactor utilized in this research could effectively upgrade biogas and simultaneously reduce the nutrient content in digestate. Red light was determined as the optimal light wavelength for microalgae growth, biogas upgrading, and digestate nutrient reduction. In the range of moderate light intensities (i.e., 800, 1200, 1600, and 2000μmolm−2s−1), higher light intensities achieved higher biogas upgrade and larger digestate nutrient reduction. Methane content attained the highest value of 92.74±3.56% (v/v). The highest chemical oxygen demand, total nitrogen, and total phosphorus reduction efficiency of digestate were 85.35±1.04%, 77.98±1.84%, and 73.03±2.14%, respectively. Considering the reduction and economic efficiencies of the carbon dioxide content of biogas and digestate nutrient as well as the biogas upgrading standard, the optimal light intensity range was determined to be from 1200 to 1600μmolm−2s−1.
Degradation solutions containing atrazine need to be further purified before they are discharged into the aquatic environment. With the objectives of evaluating removal capacity of the microalga ...Chlorella sp. toward atrazine in degradation solutions and toxicity of the degradation products, we investigated the removal efficiency (RE) and bioaccumulation of atrazine in the microalgae after an 8 d exposure to diluted degraded solutions containing 40 μg/L and 80 μg/L of atrazine as well as degradation products in the present study. Moreover, pure atrazine solutions with similar concentrations were simultaneously inoculated with the microalgae in order to distinguish the influence of the products. The photocatalytic degradation results showed that 31.4% of atrazine was degraded after 60 min, and three degradation products, desisopropyl-atrazine (DIA), desethyl-atrazine (DEA), and desethyl-desisopropyl-atrazine (DEIA) were detected. After an 8-d exposure, 83.0% and 64.3% of atrazine were removed from the degraded solutions containing 40 μg/L and 80 μg/L of atrazine, respectively. In comparison with the control, i.e., pure atrazine solution with equal concentration, Chlorella sp. in the degraded atrazine solution showed lower RE and growth rate. The photosynthetic parameters, especially performance index (PIABS), clearly displayed the differences between treatments. The values of PIABS of Chlorella sp. cultured in degradation atrazine for 8 days were significantly lower (P < 0.01) than that in the corresponding pure atrazine, suggesting potential inhibitory effect of degradation products on the microalgae. Atrazine and the degradation products inhibited algal photosynthesis via depressed light absorption and electron transport, and reduced utilization of light energy via energy dissipation. Our results demonstrated that microalgae Chlorella sp. had an encouraging atrazine removal potential and the degradation products of atrazine may inhibit algal growth and removal capability. This study may be useful for the application of microalgae in herbicide wastewater treatment and understanding algal removal of atrazine in natural aquatic environment.
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•Chlorella sp. removed atrazine efficiently from a catalytic degradation solution.•Atrazine degradation products inhibited algal growth and removal efficiency.•Photosynthetic activity reflected the toxicity of atrazine degradation products.
To weaken the effect of receiver location error on localization accuracy and make the localization model closer to the practical scenario, this paper considers the receiver location errors, usually ...neglected in prior studies into the measurement model, and proposes an algebraic method for locating a moving source using time difference of arrival (TDOA), frequency difference of arrival (FDOA), and differential Doppler rate measurements. The proposed method is based on the pseudo-linear set of equations and two-step weighted least square estimator. Only noise values of receiver locations and three types of positioning measurements are available for processing. In addition, a new Cramér-Rao lower bound (CRLB) combining TDOA, FDOA, and differential Doppler rate in the presence of receiver location errors is also derived in this paper. Theoretical analysis and simulation results both indicate that the proposed method can attain CRLB at a moderate noise level, avoid the rank deficiency problem efficiently, and achieve a significant improvement over the existing methods.
A Chinese and Patent Cooperation Treaty (PCT) invention patented process defined as “modified atmosphere vacuum cooling (MAVC)” was developed in the current study. In traditional vacuum cooling (VC), ...air enters the vacuum chamber during pressure recovery stage at the end of the cooling process. In this study, instead of air, a gas mixture consisting of 7% O2, 7% CO2 and 86% N2 enters the chamber to achieve modified atmosphere storage. Three types of cabbages with different morphological structure, including flowering cabbage, Chinese cabbage and green cabbage were treated by MAVC and stored for 21 d under 4 ± 0.5 °C, relative humidity was controlled in the range of 90%–95%. The changes of color, sensory score, ascorbic acid, chlorophyll, respiration rate, peroxidase (POD) and catalase (CAT) activity were measured throughout the storage period. The results showed that MAVC achieved the maximum values of color, sensory score, ascorbic acid, chlorophyll and CAT, and reduced the rate of respiration and the activity of POD during storage. A comparative analysis on the three cabbages found that different leaf morphology characteristics were not the main factor affecting gas retention during MAVC, and the intercellular spaces of leaves might have greater impact on the maintaining the quality of the cabbages.
•A patented “modified atmosphere vacuum cooling (MAVC)” technique was developed.•Three types of cabbages were treated by MAVC method.•Quality of three cabbages throughout the storage period was investigated.•MAVC achieved the maximum values of most quality attributes investigated.•MAVC reduced the rate of respiration and the activity of POD during storage.
The exhaust gas temperature (EGT) baseline of an aeroengine is key to accurately analyzing engine health, formulating maintenance decisions and ensuring flight safety. However, due to the complex ...performance characteristics of aeroengine and the constraints of many external factors, it is difficult to obtain accurate non-linear features between various operating factors and EGT. In order to diagnose and forecast aeroengine performance quickly and accurately, four data-driven baseline prediction frameworks for EGT are proposed. These baseline frameworks took engine operating conditions and operating state control parameters as input variables and EGT as predicted output variables. The original data were collected from CFM56-5B engine ACARS flight data. Four typical machine learning methods, including Generalized Regression Neural Network (GRNN), Radial Basis Neural Network (RBF), Support Vector Regression (SVR) and Random Forest (RF) are trained to develop the models. Four aeroengine EGT baseline models were validated by comparing the after-flight data of another engine. The results show that the developed GRNN models have the best accuracy and computational efficiency compared with other models, and their RE and CPU calculation time on the verification set are 1.132 × 10−3 and 3.512 × 10−3 s, respectively. The developed baseline prediction frameworks can meet the needs of practical engineering applications for airlines. The methodologies developed can be employed by airlines to predict the EGT baseline for the purpose of engine performance monitoring and health management.
MicroRNAs (miRNAs) show differential expression across breast cancer subtypes, and have both oncogenic and tumour-suppressive roles. Here we report the miRNA expression profiles of 1,302 breast ...tumours with matching detailed clinical annotation, long-term follow-up and genomic and messenger RNA expression data. This provides a comprehensive overview of the quantity, distribution and variation of the miRNA population and provides information on the extent to which genomic, transcriptional and post-transcriptional events contribute to miRNA expression architecture, suggesting an important role for post-transcriptional regulation. The key clinical parameters and cellular pathways related to the miRNA landscape are characterized, revealing context-dependent interactions, for example with regards to cell adhesion and Wnt signalling. Notably, only prognostic miRNA signatures derived from breast tumours devoid of somatic copy-number aberrations (CNA-devoid) are consistently prognostic across several other subtypes and can be validated in external cohorts. We then use a data-driven approach to seek the effects of miRNAs associated with differential co-expression of mRNAs, and find that miRNAs act as modulators of mRNA-mRNA interactions rather than as on-off molecular switches. We demonstrate such an important modulatory role for miRNAs in the biology of CNA-devoid breast cancers, a common subtype in which the immune response is prominent. These findings represent a new framework for studying the biology of miRNAs in human breast cancer.
We developed a method, ChIP-sequencing (ChIP-seq), combining chromatin immunoprecipitation (ChIP) and massively parallel sequencing to identify mammalian DNA sequences bound by transcription factors ...in vivo. We used ChIP-seq to map STAT1 targets in interferon-gamma (IFN-gamma)-stimulated and unstimulated human HeLa S3 cells, and compared the method's performance to ChIP-PCR and to ChIP-chip for four chromosomes. By ChIP-seq, using 15.1 and 12.9 million uniquely mapped sequence reads, and an estimated false discovery rate of less than 0.001, we identified 41,582 and 11,004 putative STAT1-binding regions in stimulated and unstimulated cells, respectively. Of the 34 loci known to contain STAT1 interferon-responsive binding sites, ChIP-seq found 24 (71%). ChIP-seq targets were enriched in sequences similar to known STAT1 binding motifs. Comparisons with two ChIP-PCR data sets suggested that ChIP-seq sensitivity was between 70% and 92% and specificity was at least 95%.
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