Random Forest-Based Fatigue Reliability-Based Design Optimization for Aeroengine Structures

Fatigue reliability-based design optimization of aeroengine structures involves multiple repeated calculations of reliability degree and large-scale calls of implicit high-nonlinearity limit state function,leading to the traditional direct Monte Claro and surrogate methods prone to unacceptable computing efficiency and accuracy.In this case,by fusing the random subspace strategy and weight allocation technology into bagging ensemble theory,a random forest(RF)model is presented to enhance the computing efficiency of reliability degree;moreover,by embedding the RF model into multilevel optimization model,an efficient RF-assisted fatigue reliability-based design optimization framework is developed.Regarding the low-cycle fatigue reliability-based design optimization of aeroengine turbine disc as a case,the effectiveness of the presented framework is validated.The reliabilitybased design optimization results exhibit that the proposed framework holds high computing accuracy and computing efficiency.The current efforts shed a light on the theory/method development of reliability-based design optimization of complex engineering structures.

Analytical workload dependence of self-heating effect for SOI MOSFETs considering two-stage heating process

Dynamic self-heating effect(SHE)of silicon-on-insulator(SOI)MOSFET is comprehensively evaluated by ultrafast pulsed I-V measurement in this work.It is found for the first time that the SHE complete heating response and cooling response of SOI MOSFETs are conjugated,with two-stage curves shown.We establish the effective thermal transient response model with stage superposition corresponding to the heating process.The systematic study of SHE dependence on workload shows that frequency and duty cycle have more significant effect on SHE in first-stage heating process than in the second stage.In the first-stage heating process,the peak lattice temperature and current oscillation amplitude decrease by more than 25 K and 4%with frequency increasing to 10 MHz,and when duty cycle is reduced to 25%,the peak lattice temperature drops to 306 K and current oscillation amplitude decreases to 0.77%.Finally,the investigation of two-stage(heating and cooling)process provides a guideline for the unified optimization of dynamic SHE in terms of workload.As the operating frequency is raised to GHz,the peak temperature depends on duty cycle,and self-heating oscillation is completely suppressed.

Cyclic electron flow around photosystem I is required for adaptation to high temperature in a subtropical forest tree, Ficus concinna

Dissipation mechanisms of excess photon energy under high-temperature stress were studied in a subtropical forest tree seedling, Ficus concinna. Net CO2 assimilation rate decreased to 16% of the control after 20 d high-temperature stress, and thus the absorption of photon energy exceeded the energy required for CO2 assimilation. The efficiency of excitation energy capture by open photosystem Ⅱ（PSⅡ） reaction centres （Fv＇/Fm＇） at moderate irradiance, photochemical quenching （qp）, and the quantum yield of PSII electron transport （φPSⅡ） were significantly lower after high-temperature stress. Nevertheless, non-photochemical quenching （qNP） and energy-dependent quenching （qE） were significantly higher under such conditions. The post-irradiation transient of chlorophyll （Chl） fluorescence significantly increased after the turnoff of the actinic light （AL）, and this increase was considerably higher in the 39 ℃-grown seedlings than in the 30 ~C-grown ones. The increased post-irradiation fluorescence points to enhanced cyclic electron transport around PSI under high growth temperature conditions, thus helping to dissipate excess photon energy non-radiatively.

Comparison and Correlation of Magnetic Resonance Imaging and Clinical Severity in Nonhuman Immunodeficiency Virus Patients with Cryptococcal Infection of Central Nervous System

Background:The incidence of cryptococcal meningitis among immunocompetent patients increases,especially in China and imaging plays an important role.The current study was to find the correlation between magnetic resonance imaging (MRI)manifestation and clinical severity in nonhuman immunodeficiency virus patients with cryptococcal infection of central nervous system (CNS). Methods:A total of 65 patients with CNS cryptococcal infection from August 2014 to October 2016 were retrospectively included in this study.All the patients had MRI data and clinical data.The patients were divided into two groups according to whether the patients were confirmed with identifiable underlying disease.Comparison and correlation of MRI and clinical data in both groups were investigated using independent sample t-test,Chi-square test,Mann-Whitney test and Spearman rank correlation analysis. Results:In all 65 patients,41 cases (41/65,63.1%;Group 1)had normal immunity and 24 cases (24/65,36.9%;Group 2)had at least one identifiable underlying disease.Fever,higher percentage of neutrophil (NEUT)in white blood cell (WBC),and increased cell number of cerebral spinal fluid (CSF)were much common in patients with underlying disease (Group 1 vs.Group 2:Fever:21/41 vs.21/24,x^2 =8.715,P =0.003;NEUT in WBC:73.15%vs.79.60%,Z=-2.370,P =0.018;cell number of CSF:19 vs.200,Z=-4.298,P <0.001;respectively).Compared to the patients with normal immunity,the lesions are more common in the basal ganglia among patients with identifiable underlying disease (Group 1 vs.Group 2:20/41 vs.20/24,x^2 =7.636,P =0.006).The number of the involved brain areas in patients with identifiable underlying disease were well correlated with the number of cells and pressure of CSF (r =-0.472,P =0.031,r =0.779,P =0.039;respectively). Conclusions:With the increased number of the involved brain areas in patients with identifiable underlying disease,the body has lower immunity against the organism which might result in higher intracranial pressure and more severe clinical status.

Clinical features in a man with primary synovial sarcoma of the spermatic cord

Dear Editor, Synovial sarcoma （SS） is a rare malignant neoplasm in young adults？ It commonly arises around the major joints or tendon sheaths. Furthermore, it has been described in numerous locations unrelated to joint structures, such as the heart, kidney, prostate, etc., which may lead to a diagnosis pitfall. Here, we present an extremely rare case of primary SS originating in the spermatic cord.