Rolling element bearing weak fault diagnosis based on spatial correlation and ALIFD

Vibration signals of rolling element bearings during operation are always very complex, random strongly and broadband. Adaptive Local Iterative Filtering Decomposition (ALIFD) can overcome the smoothness and adaptive flaws of Iterative Filtering Decomposition (IFD), but it is so susceptible to random noise that it’s less effective. Here, spatial correlation was proposed. Firstly, the signal was denoised by spatial correlation and decomposed into several modes by ALIFD. Finally, the envelope demodulation was analyzed to extract fault feature. The simulating signal analysis and bearing fault simulator show that this method can be available for separating different frequencies of bearing fault vibration signals

A revised averaging method and general forms of approximate solution for nonlinear oscillator with only polynomial-type displacement nonlinearity

In this paper a revised averaging method is presented, that does not need the detuning factor in the solving procedure. Comparison with the traditional averaging method shows that it has the similar solving procedure and the same result as the primary resonance of the traditional averaging method. Then the nonlinear oscillator with only polynomial-type displacement nonlinearity is studied, and the general forms of the first-order approximate solution by this revised averaging method, and by the traditional averaging method for the super-harmonic resonance and sub-harmonic resonance are established. At last, the Duffing oscillator is investigated as an example, and the comparison of the analytical and numerical results proves the validity and simplicity of the presented method

On the Convergence of Continuous-Time Waveform Relaxation Methods for Singular Perturbation Initial Value Problems

This paper extends the continuous-time waveform relaxation method to singular perturbation initial value problems. The sufficient conditions for convergence of continuous-time waveform relaxation methods for singular perturbation initial value problems are given

Responses of Hydroponically Grown Sorghum (Sorghum bicolor L.M) to Zinc (Zn) Stress

Abiotic stress especially due heavy metals is one of the major environmental problems that threatens food security and pose greater risks to human health worldwide. In this research, greenhouse hydroponic experiments were carried out to study the morphological and biochemical responses of Sorghum bicolor L.M to different Zinc (Zn) levels. Two-week-old seedlings transplanted in hydroponic solutions were treated with different doses of Zn in the concentration ranges of 5, 25, 50, 100 and 200 mg/L supplied as ZnSO4. 5H2O. After 21 day of culture, the plants were harvested, blotted to dryness and separated into roots and shoots. The root and shoot lengths, dry weights and non-enzymatic biochemical parameters such as proline, Chlorophyll a, b, Carotenoids (pigments) were determined. The results indicate that Zn applications significantly (P<0.05) depressed the lengths of root and shoot, dry weights and pigment contents compared to untreated plants (control). The effects were more pronounced with increased Zn dosage. The accumulation of the metal and proline contents in treated plants however, increase gradually with increasing Zn concentrations (P<0.05). The changes in these parameters had resulted in toxicity symptoms and overall growth retardation especially at elevated concentrations and the estimated critical toxicity thresholds in both solution and tissue concentrations suggest that sorghum bicolor L.M should not be grown beyond Zn concentration of above 3.2 mg/L. &nbsp

An efficient optimal design methodology for abnormal noise control of automobile transmission in the neutral idle condition

The modal analysis of the automobile transmission housing assembly is formulated using 3D graphics software Pro/E together with Finite Element Method in order to reduce the noise and vibration by accurately identifying the noise source of the transmission in the neutral idle condition. Besides, the calculation of meshing frequency of gear pair is conducted. After comparing model analysis results with the calculation results, we can intuitively analysis the dynamic characteristics of the transmission housing assembly and find out sensitive parts of the housing vibration. In order to enhance the structural stiffness of the transmission housing assembly and allow intentionally the natural frequency of the transmission to avoid the gear meshing frequency, we increase the thickness of thin plate or add the strengthening rib on the weak parts of the transmission housing assembly. The results of the above modified modal reanalysis show that low mode frequencies of the transmission housing assembly are greatly improved after optimization, and avoid the gear meshing excitation frequency effectively. The probability of resonance for the transmission housing assembly in use will be greatly reduced, which can well achieve the purpose of enhancing the dynamic characteristics of the transmission housing assembly

Guizhi-jia-houpu-xingzi decoction attenuates ovalbumin-induced allergic asthma via regulation of Toll-like receptor signal pathway

Purpose: To study the effect of Guizhi-jia-houpu-xingzi (GHX) on ovalbumin-induced allergic asthma in rats.Methods: An animal model of allergic asthma (AA) in rats was established by intraperitoneal injection (ip) of ovalbumin (OVA). Thereafter, GHX (375 mg/kg) was administered orally for 7 days. Pulmonary function, inflammatory cells, immunoglobulin E (Ig) E, interleukin-4 (IL)-4 and interferon-γ (IFN)-γ in serum and bronchoalveolar lavage fluids (BALF) were determined. Furthermore, mRNA expressions of Toll-like receptors (TLRs) signal pathway was determined using real time polymerase chain reaction PCR (q-RT-PCR).Results: GHX (375 mg/kg) significantly decreased respiratory rate (p < 0.01) and Penh value (p < 0.05) when compared with AA rats. The inflammatory cells (p < 0.01) and levels of IL-4 (p < 0.01) and IgE (p < 0.01) were significantly decreased by GHX treatment when compared with AA rats; whereas IFN-γ (p < 0.05) was significantly increased. Furthermore, GHX significantly decreased the mRNA expressions of GATA binding protein (GATA)-3 (p < 0.01), TRL-2 (p < 0.01), TRL-4 (p < 0.01), myeloid differentiation factor 88 (MyD88) (p < 0.01), TNF receptor associated factor 6 (TRAF6) (p < 0.01) and β-arrestin (p < 0.01) in lung tissues, relative to AA rats. However, GHX treatment led to significant up-regulation of mRNA expression of T-bet (p < 0.01).Conclusion: These results demonstrate that GHX possesses a potential for treating allergic asthma via regulation of Toll-like receptor (TLR) signal pathway. They also provide a scientific basis for the probable use of GHX in clinical treatment of allergic diseases in future.Keywords: Guizhi-jia-houpu-xingzi decoction, Ovalbumin, Allergic asthma, Toll-like recepto

Simulation of dynamic performance and wheel-rail wear of railway wagon under deviation of cargo gravity center

A multibody dynamic model of railway wagon is established by Simpack software, and the derailment coefficient, wheel load reduction rate, impact angle and wear index of freight car are calculated under different gravity center offsets and different curve conditions. The simulation results show that the lateral and longitudinal offsets of cargo gravity center have a great influence on the derailment coefficient, wheel unloading rate, impact angle and wear index of the vehicle. The larger the offset of the cargo gravity center is, the worse the operation performance of the wagon is, the more serious the wheel-rail wear is, and the shorter the transport life of the wagon is. The smaller the radius of the curve is, the greater the impact is

Xanthohumol inhibits PRRSV proliferation and alleviates oxidative stress induced by PRRSV via the Nrf2–HMOX1 axis

International audiencePorcine reproductive and respiratory syndrome virus (PRRSV) is a prevalent and endemic swine pathogen that causes significant economic losses in the global swine industry. Commercial vaccines provide limited protection against this virus, and no highly effective therapeutic drugs are yet available. In this study, we first screened a library of 386 natural products and found that xanthohumol (Xn), a prenylated flavonoid found in hops, displayed high anti-PRRSV activity by inhibiting PRRSV adsorption onto and internalization into cells. Transcriptome sequencing revealed that Xn treatment stimulates genes associated with the antioxidant response in the nuclear factor-erythroid 2-related factor 2 (Nrf2) signalling pathway. Xn causes increased expression of Nrf2, HMOX1, GCLC, GCLM, and NQO1 in Marc-145 cells. The action of Xn against PRRSV proliferation depends on Nrf2 in Marc-145 cells and porcine alveolar macrophages (PAMs). This finding suggests that Xn significantly inhibits PRRSV proliferation and decreases viral-induced oxidative stress by activating the Nrf2–HMOX1 pathway. This information should be helpful for developing a novel prophylactic and therapeutic strategy against PRRSV infection