Foreign Object Damage to Fan Rotor Blades of Aeroengine Part I: Experimental Study of Bird Impact

AbstractThe conditions of experiment for bird impact to blades have been improved. The experiment of bird impact to the fan rotor blades of an aeroengine is carried out. Through analyzing the transient state response of blades impacted by bird and the change of blade profile before and after the impact, the anti-bird impact performance of blades in the first fan rotor is verified. The basis of anti-foreign object damage design for the fan rotor blades of an aeroengine is provided

Foreign Object Damage to Fan Rotor Blades of Aeroengine Part II: Numerical Simulation of Bird Impact

AbstractBird impact is one of the most dangerous threats to flight safety. The consequences of bird impact can be severe and, therefore, the aircraft components have to be certified for a proven level of bird impact resistance before being put into service. The fan rotor blades of aeroengine are the components being easily impacted by birds. It is necessary to ensure that the fan rotor blades should have adequate resistance against the bird impact, to reduce the flying accidents caused by bird impacts. Using the contacting-impacting algorithm, the numerical simulation is carried out to simulate bird impact. A three-blade computational model is set up for the fan rotor blade having shrouds. The transient response curves of the points corresponding to measured points in experiments, displacements and equivalent stresses on the blades are obtained during the simulation. From the comparison of the transient response curves obtained from numerical simulation with that obtained from experiments, it can be found that the variations in measured points and the corresponding points of simulation are basically the same. The deforming process, the maximum displacements and the maximum equivalent stresses on blades are analyzed. The numerical simulation verifies and complements the experiment results

Electrochemically Fabricated Surface-Mesostructured CuNi Bimetallic Catalysts for Hydrogen Production in Alkaline Media

Ni-based bimetallic films with 20 at.% and 45 at.% Cu and mesostructured surfaces were prepared by electrodeposition from an aqueous solution containing micelles of P123 triblock copolymer serving as a structure-directing agent. The pH value of the electrolytic solution had a key effect on both the resulting Cu/Ni ratio and the surface topology. The catalytic activity of the CuNi films toward hydrogen evolution reaction was investigated by cyclic voltammetry (CV) in 1 M KOH electrolyte at room temperature. The CuNi film showed the highest activity (even higher than that of a non-mesostructured pure Ni film), which was attributed to the Ni content at the utmost surface, as demonstrated by CV studies, as well as the presence of a highly corrugated surface

Comparison Study on Interlaminar Shear Strength Testing Methods of CFRP under Hygrothermal Aging Conditions

The effects of hygrothermal aging on the interlaminar shear strength of T700/TDE-85 composites were studied by short-beam method and double-incision method. The relationship between moisture absorption and aging time was discussed, and the fracture surface morphology was analyzed. The experimental results show that the moisture absorption law of the two specimens is in accordance with Fickle's second law, but the saturated moisture absorption rate and moisture absorption time are different. The moisture absorption rates and saturated moisture absorption rates of the specimens of double incision method are higher than those of the short beam method. The interlaminar strength of double-incision test is more obvious than that of short-beam under hygrothermal aging conditions, the interlaminar shear strength retention rates of short-beam method's specimens are 74.5%, 61.0%, 53.2% and 50.6% at 500 h intervals and the interlaminar shear strength retention rates of double-incision method's specimens are 60.9%, 38.3%, 42.6% and 33.0% at 500 h intervals. The failure mode of short-beam specimen is more complicated than that of double-incision with the increase of hygrothermal aging time

Primary central nervous system lymphoma with ependymal involvement: analysis of clinical manifestations and cerebrospinal fluid cytological features of 4 cases

Objective To analyse clinical and cerebrospinal fluid cytological features of primary central nervous system lymphoma (PCNSL) with ependymal involvement and investigate the diagnostic value of cerebrospinal fluid cytology. Methods Clinical and radiological features of 4 cases of PCNSL were reviewed retrospectively. The findings in conventional cytology and immunocytochemistry of cerebrospinal fluid were analysed. Results All of the patients suffered from headache. Meningeal irritation signs were positive in all the 4 cases. Other clinical features were as follow: radiculoneuropathy in 2 cases, multiple cranial nerves paralysis in one case, hemiplegia in one case, and intermittent low-grade fever in 3 cases. Two cases died of cerebral hernia 2-4 months later after the onset. Lumber puncture was performed in 3 cases and intracranial hypertension was found in 2 cases. One case received ventricular drainage. Cerebrospinal fluid examination showed lymphocyte pleocytosis (4 cases) with elevated protein (4 cases) and lower glucose level (3 cases). The examination of cerebrospinal fluid found lymphocyte pleocytosis with remarkable atypical lymphoma cells in all of the cases. Among 3 patients received cerebrospinal fluid immunocytochemical studies, the lymphocytes were positive for CD19, CD20, CD79a and implied a B-lymphocyte source. Brain magnetic resonance imaging (MRI) showed irregular enhancement of the ventricular wall with nodular periventricular and septal enhancement in part of the 4 cases and pituitary enhancement in one case. Two patients were diagnosed via biopsy of the brain, which showed non-Hodgkin's lymphoma. The other two were diagnosed through cytology and immunocytochemical studies of cerebrospinal fluid. One case received positron emission tomography (PET) examination, which showed no evidence of extracranial involvement. Bone marrow biopsy in other patients were normal too. Conclusion Cytological and immunocytochemical studies of cerebrospinal fluid specimen should be stressed in the diagnosis of PCNSL. This report also emphasizes the importance of clinical and radiological findings in the diagnosis of this disease. DOI：10.3969/j.issn.1672-6731.2011.05.01

Effect of the Interaction between Obstructive Sleep Apnea and Lipoprotein(a) on Insulin Resistance: A Large-Scale Cross-Sectional Study

Both obstructive sleep apnea (OSA) and decreased serum lipoprotein(a) (Lp(a)) concentrations are associated with insulin resistance. However, their interaction effect on insulin resistance has never been investigated. Therefore, we performed a cross-sectional study on OSA-suspected Chinese Han participants. Laboratory-based polysomnographic variables, biochemical indicators, anthropometric measurements, and medical history were collected. Linear regression and binary logistic regression analyses with interaction terms were used to investigate the potential effects of the interaction between the severity of OSA (assessed by the apnea-hypopnea index (AHI)) and Lp(a) concentrations on insulin resistance (assessed by the homeostasis model assessment of insulin resistance (HOMA-IR)), after adjusting for potential confounders including age, gender, body mass index, waist-to-hip circumference ratio, mean arterial pressure, smoking status, drinking status, and lipid profiles. A total of 4,152 participants were enrolled. In the OSA-suspected population, AHI positively correlated with insulin resistance and serum Lp(a) concentrations independently and inversely correlated with insulin resistance. In addition, the interaction analysis showed that the linear association between lgAHI and lgHOMA-IR was much steeper and more significant in subjects with relatively low Lp(a) concentrations, suggesting a significant positive interaction between lgLp(a) and lgAHI on lgHOMA-IR (P=0.013). Furthermore, the interaction on a multiplicative scale also demonstrated a significant positive interaction (P=0.044). A stronger association between AHI quartiles and the presence of insulin resistance (defined as HOMA-IR > 3) could be observed for participants within lower Lp(a) quartiles. In conclusion, a significant positive interaction was observed between OSA and decreased Lp(a) with respect to insulin resistance. This association might be relevant to the assessment of metabolic or cardiovascular disease risk in OSA patients