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Propagation of a semi-elliptical crack on the suction surface of a rotating blade of a gas turbine compressor is modelled and analysed. The analytical solution for the stress intensity factor (SIF) at the deepest point of the crack shows that the SIF increases with an increase in the crack depth and rotation speed, whereas the SIF decreases with an increase in the semi-elliptical aspect ratio and crack-rotation axis distance. The SIF increase rate with increasing crack depth is found to depend on the aspect ratio. Comparisons of theoretical and numerical calculation results reveal a relative error within 4%. The SIF distribution along the semi-elliptical surface crack front at different depths, positions, and aspect ratios are obtained by a numerical method.

The failure of many aircraft structures and materials is caused by the accumulation of fatigue damage under variable-amplitude cyclic loading wherein the damage evolution of materials is complicated. Therefore, to study the cumulative fatigue damage of materials under variable-amplitude cyclic loading, a new nonlinear fatigue damage accumulation model is proposed based on the ecological quality dissipation of materials by considering the effects of load interaction and sequence. The proposed new model is validated by the test data obtained for three kinds of material under multilevel fatigue loading. Compared with the Miner model and Kwofie model, the proposed model can more effectively analyse the accumulative damage and predict fatigue life of different materials under variable-amplitude cyclic loading than others. The study provides a basis for predicting fatigue life accurately and determining reasonable maintenance periods of aircraft structures.

Objective To investigate the clinical efficacy of continuous renal replacement therapy (CRRT) combined with immunoabsorption and plasma exchange in the treatment of antibody-mediated rejection (AMR) complicated with multiple organ failure after renal transplantation. Methods Twenty-eight patients diagnosed with AMR complicated with multiple organ failure after renal transplantation were randomly divided into the control group (n=12) and treatment group (n=16).All patients were given with methylprednisolone 0.8 g/d shock therapy for 5 d, oral intake of ciclosporin 1.5 mg/(kg·d), CRRT, cardiotonics, diuretics and other symptomatic treatments.In the treatment group, immunoabsorption and plasma exchange were delivered on the 7th and 10th d after treatment.The overall conditions were statistically compared between two groups.The changes of renal function [blood urea nitrogen (BUN), serum creatinine (Scr)] and blood electrolyte before and after treatment were compared between two groups.The results of histopathological examination and immunohistochemical staining of the renal tissues before and after treatment were analyzed in two groups. Results Among 28 patients, 24 cases were clinically cured, including 14 in the treatment group and 10 in the control group.The symptoms of 3 patients were deteriorated, including 2 in the treatment group and 1 in the control group.One patient in the control group died of cerebral hemorrhage.After 7 d and 12 d treatment, the levels of BUN and Scr significantly differed between the treatment group and control group (P < 0.05-0.01).The levels of blood sodium and potassium significantly differed between two groups before and after treatment (P < 0.05-0.01).Pathological examination of renal tissue demonstrated that after 12 d treatment, the number of lymphocytes infiltrated in the transplanted kidney tissues was reduced and the degree of vasculitis was alleviated in two groups.Compared with the control group, the pathological scores of glomerulus, tubulointerstitial and blood vessels were significantly lower in the treatment group (all P < 0.01).Immunohistochemical staining revealed that after 12 d treatment, the number of ED1-positive monocytes in the transplanted kidney tissues was declined in both groups, especially in the treatment group.Following 12 d treatment, the ratio of CD4+/CD8+ cells in renal tubulointerstitial in the treatment group was significantly lower than that in the control group (P < 0.01). Conclusions CRRT combined with immunoabsorption and plasma exchange is an effective method to treat AMR complicated with multiple organ failure following renal transplantation.

Modeling the residual stress of TBCs near the interfacial asperity on turbine component tends to encounter numerical cumbersomeness ordinarily due to huge computational scale and complex mechanical behavior. This paper proposed a numerical method named submodeling method to simulate the local stress near the asperity by a partition model (named submodel) of a coated vane, based on the submodeling technique of ABAQUS code. First a global mechanical analysis about the coated vane was carried lasting three thermal cycles without considering interface asperities. Then a submodel was established with asperity and divided into three unique zones with proper mesh density according to their functions. Finally the local mechanical analysis was separately processed by submodeling method, based on interpolation of the solution from the global analysis onto the outer zone of the submodel. The results show that the stress level of TC near the asperity is relatively low after 3 thermal cycles. The normal stress and the shear stress of BC near the asperity are concentrated in the peak and nearby the trough, respectively. These stress concentrations may lead to TGO/BC interfacial crack. The stress values and distribution feature of BC near the asperity is quite agreement with former results. These may prove that submodeling method can be applicable for local stress modeling and failure prediction.

In this paper, a marine dual-rotor gas turbine is taken as the research object, and a dual-rotor system model with a simplified structure and supported by intermediary bearings is established based on its structural characteristics and nonlinear characteristics of bearings. The Lagrange equation of motion is used to derive the differential equations of motion of the system, and the fourth-order Runge-Kutta method is used to solve the equations. The nonlinear dynamic response and bifurcation chaotic characteristics of the dual-rotor system with speed changes are studied. The results show that when the speed is low, the system is in a single-cycle motion. As the rotational speed increases, the system exhibits multiplicative bifurcation, Hopf bifurcation and chaotic behaviour. This result provides theoretical guidance for the design and safe and stable operation of the rotor system.

Bearing is one of the most important components of rotating machinery. The vibration signals are generally nonlinear and nonstationary while operating. The failed rolling bearing will damage to the machine, or cause a serious loss of property. There are a lot of methods about fault diagnosis of bearing, such as shock pulse method, resonance demodulation. Especially the HHT (Hilbert-Huang Transform) method with the adaptive advantage has gradually become a very promising method to extract the characteristics of nonlinear, nonstationary signal. In this paper the variant energy method was introduced in HHT to reduce the computation of the decomposed signal, which effectively improved the computation, and then an experimental platform was designed and established. The bearing fault categories can be diagnosed correctly in dealing with the vibration signals using this method and the fault law is discovered that the trend of the vibration signal fault characteristic frequency amplitude changes with the load increasing. The bearing failure mechanism provides beneficial reference for further research of nonlinear signal analysis.

Novel porous β-Bi2O3/Bi2O2CO3 p-n heterostructures were synthesized by partially decomposing porous Bi2O2CO3 at 300-375 °C. The structures, morphologies, optical properties, and specific surface areas of the as-synthesized samples were characterized by means of thermogravimetry and differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, UV-Vis spectroscopy, and N2 gas adsorption. Two types of dyes, methyl orange (MO) and methylene blue (MB), were chosen as model organic pollutants to evaluate the photocatalytic activity of the as-synthesized samples. The porous β-Bi2O3/Bi2O2CO3 p-n heterostructures exhibited much higher photocatalytic activity than β-Bi2O3 and Bi2O2CO3 and MO and MB could be completely degraded within 24 and 50 min, respectively. In addition, phenol as a colorless organic pollutant was also chosen to further study the photocatalytic activity of Bi2O2CO3, β-Bi2O3 and β-Bi2O3/Bi2O2CO3. The β-Bi2O3/Bi2O2CO3 heterostructures also showed much higher photocatalytic activity for the photodegradation of phenol than β-Bi2O3 and Bi2O2CO3. The obtained results indicated that the formed p-n heterojunction in the porous β-Bi2O3/Bi2O2CO3 composite significantly contributed to the improvement of electron-hole separation and the enhancement of photocatalytic activity. The mechanisms for the enhanced photodegradation of selected organic pollutants over the β-Bi2O3/Bi2O2CO3 composite are discussed in this study. Fil: Zhu, Gangqiang. Shaanxi Normal University; China Fil: Liu, Yongbao. Shaanxi Normal University; China Fil: Hojamberdiev, Mirabbos. Turin Polytechnic University in Tashkent; Uzbekistán Fil: Han, Juanli. Shaanxi Normal University; China Fil: Rodríguez, Juan. Universidad Nacional de Ingeniería; Perú Fil: Aldabe, Sara Alfonsina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina Fil: Liu, Peng. Shaanxi Normal University; China

To resolve cause-missed in the fault diagnosis, Extended Fuzzy Timed Petri Nets (EFTPN) was used in this paper; Some tasks were done in this paper. First, a algorithm of EFTPN was defined in this paper. Second, some assumptions were given to the model and algorithm of fault diagnosis was built in this paper. The algorithm resolved the cause-missing-problem to the utmost by checking the states of all fault cause of the whole system at the time when a fault occurred. And the algorithm also found the primary cause. In the end, the model is proved to be availability by the example about fault diagnosis in this paper.