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  • Author: Shi Wang x
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Abstract

This paper puts forward a reliability estimation method by the Degradation Amount Distribution (DAD) of products, using a composite time series modeling procedure and grey theory based on a random failure threshold. Product DAD data are treated as a composite time series and described using a composite time series model to predict a long-term trend of degradation. The degradation test is processed for a certain electronic product and the degradation data is collected for reliability estimation. Comparison among the reliability evaluation by DAD composite time series analysis and grey theory, based on a constant and a random failure threshold, reliability evaluation by DAD regression analysis based on a random failure threshold, reliability evaluation by degradation path time series analysis, and real reliability of the electronic product is done. The results show that the reliability evaluation of the product using the method proposed is the most creditable of all.

Abstract

A new approach to achieve fault diagnosis and prognosis of bearing based on hidden Markov model (HMM) with multi-features is proposed. Firstly, the time domain, frequency domain, and wavelet packet decomposition are utilized to extract the condition features of bearing vibration signals, and the PCA method is merged into multi-features to reduce their dimensionality. Then the low-dimensional features are processed to obtain the scalar probabilities of each bearing condition, which are multiplied to generate the observed values of HMM. The results reveal that the established approach can well diagnose fault conditions and achieve the remaining life estimation of bearing.

Transcription factor NF-E2-related factor 2 (Nrf2) is important for cell protection against chemical-induced oxidative stress. Previously, we have reported that in PC12 cells, Nrf2 can be triggered by deltamethrin (DM), a commonly used pyrethroid insecticide. Molecular mechanisms behind Nrf2 activation by DM are still unclear. Here we studied the effects of cell glutathione (GSH) depletion on Nrf2 activation by DM. We found that DM enhanced Nrf2 expression at the mRNA and protein levels and increased nuclear Nrf2 levels. Activation of Nrf2 was associated with activation of its downstream targets, such as heme oxygenase-1 (HO-1) and glutamate cysteine ligase catalytic subunit (GCLC). In contrast, DL-buthionine-[S,R]- sulfoximine (BSO), a known GSH-depleting agent, did not increase Nrf2 protein expression or cause its nuclear accumulation. However, pre-treatment with BSO triggered mRNA expression of HO-1 and GCLC. Furthermore, BSO pre-treatment suppressed DM-induced Nrf2 upregulation and activation and lowered mRNA expression of HO-1 and GCLC upon DM treatment. These data demonstrate that GSH depletion is not necessary for the activation of Nrf2/ARE by DM in PC12 cells, and that GCLC and HO-1 expression can increase through other signalling pathways.

Abstract

In order to handle the non-linear system and the complex disturbance in marine engines, a finite-time convergence active disturbance rejection control (ADRC) technique is developed for the control of engine speed. First, a model for the relationship between engine speed and fuel injection is established on the basis of the mean value engine model. Then, to deal with the load disturbances and model parameter perturbation of the diesel engine, this paper designs an ADRC approach to achieve finite-time stability. Finally, simulation experiments show that the proposed method has better control effect and stronger disturbance rejection ability in comparison with the standard linear ADRC.

Abstract

The most feared of hazards in underground mines are those of fires and explosions. This study focuses on the temperature-rising process of residual coal under spontaneous combustion condition in coal mine gob. A numerical model has been established considering the chemical reaction, heat transfer and components seepage flow. The temperature distributions and maximum values for different positrons at various times have been calculated by using the coupled model. An experimental model has been also developed for model calibration. The validation indicates the numerical model is accurate and suitable for solving the temperature-rising problem in coalmines. The simulation results show that high temperature zone appears at the air intake roadway side in the gob and enlarging the ventilation flux increases the risk of self-ignition of coal. The research results can be used to predict the temperature-rising of coal spontaneous combustion and coal resources prevention.

Abstract

Coal spontaneous combustion is an extremely complicated physical and chemical changing process. In order to improve the indicator gases detection technology and coal spontaneous combustion monitoring, a novel forecast method for toxic gases emission from coal oxidation at low temperature is presented in this paper. The experiment system is setup combined with frequency-domain terahertz technology and coal temperature programming device. The concentration curves of carbon monoxide and sulphur dioxide gases from coal spontaneous combustion are estimated according to molecule terahertz spectra. The influences of coal rank and oxygen supply on coal spontaneous combustion characteristics are discussed. Both carbon monoxide and sulphur dioxide gases absorption spectra show the characteristic equi-spaced absorption peaks. Results demonstrate that under the condition of lean oxygen, there exists a critical oxygen concentration in the process of coal oxidation at low temperature. Comparing with Fourier infrared spectrum testing, the presented method is highly accurate and more sensitive, especially suitable for early-stage monitoring of the indicator gases produced by coal spontaneous combustion.

Abstract

The most attractive structural feature of the three-dimensional (3D) angle-interlock woven structure is that the straight weft yarns are bundled by the undulated warp yarns, which induces the overall good structural stability and a stable fabric structure. Thus the 3-D angle-interlock woven composite (3DAWC) prepared by the vacuum-assisted resin transfer molding (VARTM) curing process has excellent mechanical properties by using the fabric and epoxy resin as the reinforcement and matrix, respectively. The low-velocity impact damage properties of the composites under different drop-weight energies (70, 80, and 100 J) were tested experimentally. The load–displacement curves, energy–time curves, and the ultimate failure modes were obtained to analyze the performance of resistance to low-velocity impact, as well as the impact energy absorption effect and failure mechanism, especially the structural damage characteristics of the 3DAWC subjected to the low-velocity impact of drop weight. By analyzing the obtained experimental results, it is found that the fabric reinforcement is the primary energy absorption component and the impact energy mainly propagates along the longitudinal direction of the yarns, especially the weft yarn system, which is arranged in a straight way. In addition, as the impact energy increases, the energy absorbed and dissipated by the composite increases simultaneously. This phenomenon is manifested in the severity of deformation and damage of the material, i.e., the amount of deformation and size of the damaged area.

Abstract

Introduction: The differentially expressed proteins between healthy cows and those with footrot were identified to explore changes in protein profiles associated with the disease. Material and Methods: Out of 36 cows selected for the experiment, 18 footrot-affected cows were included in the treatment group (group T) and 18 unaffected cows were included in the control group (group C). Plasma samples from groups T and C were subjected to two-dimensional electrophoresis analysis and differentially expressed proteins were identified by matrix-assisted laser desorption/ionisation tandem time-of-flight mass spectrometry. Bioinformatics, including gene ontology analysis and pathway analysis, was used for analysing all proteins. Results: Out of 63 spots identified by 2DE, 33 were selected for mass spectrum analysis, which identified 11 differentially expressed proteins in 26 spots. Footrot led to changes in profiles in plasma proteins that were classified to the pathway of inflammatory response, complement, and blood coagulation, among others. Conclusion: This study provides evidence of the defence mechanisms of cows with footrot to explore strategies for treatment.

Abstract

A set of eight simple sequence repeat (SSR) markers were developed from 707 Salix expressed sequence tags (ESTs) deposited in GenBank. Each of the EST-SSR amplicons was identical to the original EST, with sequence identity 60.90-96.03% and presence of the expected repeat motifs. Of the eight EST-SSR loci, five were polymorphic among 14 individuals of S. eriocephala, with the number of alleles per locus (Na), observed heterozygosity (Ho), expected heterozygosity (He) and polymorphic information content (PIC) being 2-7 (mean 4.8), 0.29-0.85 (mean 0.65), 0.25-0.84 (mean 0.65) and 0.21-0.78 (mean 0.58), respectively. High rates of crossspecies/ genus amplification were also observed within fourteen different species. The primer sequences for the eight EST-SSRs have been deposited in the Probe database of GenBank (IDs Pr031820546 - Pr031820553). The EST-SSRs developed herein would be a valuable addition of functional markers for genetics and breeding applications in a wide range of Salix species.

Abstract

Background: Recently bismuth-based nanoparticles have attracted increasing attention as a dose amplification agent in radiation therapy due to high atomic number, high photoelectric absorption, low cost, and low toxicity.

Objectives: This study aims to calculate physical aspects of dose enhancement of bismuth-based nanoparticles in the presence of brachytherapy source by Monte Carlo simulation and an analytical method for low mono-energy. Materials and methods: After simulation and validation brachytherapy sources (Iodine-125 and Ytterbium-169) by Monte Carlo code, bismuth-based nanoparticles (bismuth, bismuth oxide, bismuth sulfide, and bismuth ferrite) were modeled in the sizes of 50 nm and 100 nm for two concentrations of 10 and 20 mg/ml. Dose enhancement factors for the bismuth-based nanoparticles were measured at both brachytherapy sources. Furthermore, the dose amplification was calculated with an analytic method at 30 keV mono-energy.

Results: Dose enhancement factor was greatest with pure bismuth nanoparticles, followed by bismuth oxide, bismuth sulfide and bismuth ferrite for both radiation source and simulation methods. The dose amplification for the bismuth-based nanoparticles increased with increasing size and concentration of nanoparticles.

Conclusion: The physical aspect dose enhancement of the nanoparticles was shown by Monte Carlo and analytic method. The results have proved bismuth-based nanoparticles deserve further study as a radiosensitizer.