A non‐linear life prediction model considering the loading history is proposed based on isodamage curve. The stress‐controlled low‐high block loading of low cycle fatigue (LCF) at high temperature, ...with various previous cycles, was performed on a nickel‐based superalloy. The damage evolvement of the prior loading was revealed using scanning electron microscopy under the low‐high block loading, especially the failure mechanism of coaxing effect. In addition, load history correlation factor was introduced to describe the influence of prior cycle. Based on the Ni‐based superalloy, the life prediction model of two‐step loading, including the low‐high block (LH) and high‐low block loading (HL), was proposed, agreeing well with the experimental results for different metals. Compared with other life prediction models, the proposed model demonstrated the higher prediction accuracy and wider applicability.
Highlights
A nonlinear fatigue life prediction model was established considering coaxing effect.
No fitted material parameters were included in the new model.
A damage exponent of loading history was introduced based on the SEM results.
Proposed model performed excellent prediction ability for the two‐block loading.
•InAs QDs with different As flux during growth interruption are grown by MOCVD.•AFM shows a raised height of QDs with increase of As flux.•As flux have impacts on PL wavelength, intensity and ...activation energies of QDs.•QDs laser with largest As flux possesses the greatest temperature stability.
We report the effect of As flux rate (FR) during growth interruption (GI) after quantum dot (QD) deposition on the performances of InAs/InGaAsP/InP QDs and their lasers, grown by metal–organic chemical vapor deposition. The active region consists of seven layers of self-assembled InAs QDs separated by InGaAsP lattice-matched to InP. Room-temperature photoluminescence (PL) measurements show that both the PL peak intensity and emission wavelength of the active region increase with As FR. Temperature-dependent PLs reveal that the activation energies of the QDs from the ground state to higher energy level or barrier become greater with the increase of As FR, indicating less carrier thermal escape from the QDs to their barriers. These above observations can be attributed to the promoted migration and suppressed desorption of surface In atoms, leading to enlarged QDs with deepened energy levels and thus enhanced carrier quantum confinement effect. Moreover, a 6-μm-wide and 3-mm-long ridge-waveguide QD laser with the greatest As FR shows a lowest threshold current of 477 mA under pulse mode at room temperature, corresponding to a threshold current density of 379 A/cm2 per QD layer. Meanwhile, the laser exhibits the highest characteristic temperatures T0 and T1 of 331 K and 775 K, respectively, in the temperature range between 20 °C and 60 °C.
High temperature creep and fatigue properties are important characteristics of SiC/SiC composites. In this work, dwell-fatigue tests were conducted at 1300 °C for 3D-braided SiC/SiC with and without ...coatings, and experimental results of dwell-fatigue tests were analyzed together with results of fatigue and creep tests. Then, general quantitative method was adopted to explain the deformation and rupture behaviors of SiC/SiC in creep, fatigue and dwell-fatigue tests. Micromechanical creep model could effectively simulate deformation behavior when the maximum load was under matrix cracking stress. Stress transfer behavior of constituents during creep and fatigue tests provided insights into the difference in macro time/cycle dependent deformation. Next, by incorporating damage evolution model which represents oxidation assisted unbridged crack growth, deformation acceleration in tertiary stage of creep was successfully simulated. Finally, SiC/SiC lifetimes under all fatigue, creep, and dwell-fatigue loads were predicted considering matrix crack propagation and fiber strength degradation. Simulated results correlated well with experimental data, verifying the effectiveness of micromechanical model to predict the creep and fatigue behaviors of SiC/SiC composites at high temperatures.
To observe the sub-chronic toxic effects of the genetically modified rice with double antisense SBE gene.
Based on gender and weight, weanling Wistar rats were randomly sorted into five groups: ...non-genetically modified rice group (group A), genetically modified rice group (group B), half genetically modified rice group (group C), quarter genetically modified rice group (group D) and AIN-93G normal diet group (group E). Indicators were the followings: body weight, food consumption, blood routine, blood biochemical test, organ weight, bone density and pathological examination of organs.
At the middle of the experiment, the percentage of monocyte of female group B was less than that of group E (P < 0.05). AST activity of female group B was higher than that of group E (P < 0.05). ALT activity of female group C was higher than that of groups A and E (P < 0.05). At the end of the experiment, AST and ALT activities of female group B were higher than those of group E (P < 0.05). Hematocrit (HCT) and blood urea nitrog
The study empirically analyzes the stock market response to the announcements of China's Manufacturing Purchasing Managers' Index (PMI). Asymmetric effects are observed, as follows: negative PMI ...announcements do not appear to influence the stock market, whereas positive PMI announcements have a significant effect. Evidence further suggests that negative announcements remain nonsignificant under any economic period (e.g., expansion, contraction, or stability), while the positivity effect observed becomes increasingly significant during both economic expansion and stability periods. Our study is not consistent with international experience, which suggests stock markets are more sensitive to negative news. A test sample of individual stocks was used to further investigate this phenomenon. We observed stocks characterised with lower levels of institutional ownership, smaller firm size, higher liquidity or low stock prices, react to positive news more consistently. These types of stocks are generally favoured by individual investors who are more easily influenced by positive PMI news. Unlike stock markets of America or Europe, individual investors dominate China's stock market. The ‘rise‐chasing and down‐freezing’ behaviour of the individual investors may explain why China's market reacts more readily to positive PMI announcements. Note: The ‘rise‐chasing and down‐freezing’ phenomenon refers to an investor who buys winning stocks warmly, while keeps the losing stocks at hand.
•We examine the impacts of in-vehicle navigation information by driving simulator.•We test four information provision design schemes under three traffic flow status.•Lane-changing characteristics are ...analyzed by selecting six indicators.•In-vehicle navigation has positive impact on safety under medium/high density.•More improvement could be gained when the in-vehicle navigation provided earlier.
Lane-changing behaviors frequently occur at upstream of the urban expressway off-ramp, which possibly cause bottleneck or accident. This paper studies how in-vehicle navigation information impacts lane-changing behavior at this urban expressway diverge segments with comparison to the traditional road signs by conducting a series of driving simulator experiments, in consideration of variation of the first provision time point and traffic flow density. Firstly, the driving simulator is validated by comparing data of lane-changing position and merging gap from both field survey and simulator. Then comparison study was performed for twelve scenarios which comprise four information provision design schemes under three different traffic flow density status. Lane-changing characteristics are analyzed by selecting six indicators, which are lane-changing merging gap, lane-changing position, lane change delay, lane-changing steering angle, lane-changing deceleration, and the safe distance of lane-changing. The results show that the impact of in-vehicle navigation information on lane-changing behavior varies with traffic flow density and the time point of the first navigation information provided. The in-vehicle navigation information had significant positive impact on lane-changing safety under medium to high density condition. However, the effect is not significant under light density condition. Moreover, more improvement in operational safety and smooth could be gained when the in-vehicle navigation information is provided earlier within range of 2km upstream of the exit gore.
Six experimental diets of different designed protein levels in Chinese diet were consumed by 20 healthy male youths divided into two groups in three continuing 7‐day cycle separately. After 5 days¡ ...adaptation, intravenous transfusion of stable isotope labeled leucine (13C) and lysine(15N) was administrated in 3 hours. The abundances of 13CO2 and 15N‐urea in the samples were determined, then computed the flux and oxidation rate of leucine and lysine. We explored the protein requirement by constructing the two phase linear regression equations between protein intakes and amino acid oxidation rate and determined the regression curve breakpoint. We adopted the largest value of 0.83g/kg/d among all three protein requirements determined by three regression curves as the average physiological requirements for our study population, and the recommended nutrient intake of 0.96g/kg/d for protein.
Optically rough and physically flat transparent conductive (OR-PF) substrates facilitate the performance improvement of optoelectronic devices and functional glasses via simultaneously enabling ...high-quality growth of functional layers and effective light management. This paper studies the effect of the interface morphology of the hole array pattern (HAP) and the pillar array pattern (PAP) on the far-field scattering properties of OR-PF substrates fabricated by spin-coating Al-doped ZnO (AZO) on nanoimprint-patterned glasses for improving the performance of superstrate-type thin-film solar cells. Theoretical calculation based on bidirectional scattering distribution function predicts that HAP with a period of 1.5 μm and a diameter of 1.3 μm HAP(P1.5D1.3) and the PAP(P1.0D0.5) interface morphology have a haze ratio in transmission (HT) of around 64% and a scatter angle of larger than 34°. The fabricated AZO/HAP(P1.5D1.3) and AZO/PAP(P1.0D0.5) show a flat surface with a σrms of less than 9 nm, a high visible light transmittance of over 86%, a sheet resistance of about 30 Ω/sq, and strong far-field scattering. In particular, AZO/PAP(P1.0D0.5) possesses an average HT of over 11% at the wavelength range of 600–850 nm and an angular intensity distribution of over 1.5% at an azimuthal angle of around 55°, indicating stronger far-field scattering than the conventional pyramid-textured B-doped ZnO (BZO/F). Compared to the flat substrate, AZO/PAP generates an implied J sc gain of 16.2% in a CH3NH3PbI3 photoactive layer with a thickness of 300 nm under normal incidence at the wavelength range of 550–800 nm. For 60° incidence, AZO/PAP(P1.0D0.5) enables an implied J sc gain of 2.3% with respect to BZO/F. As applied to the front electrode of CH3NH3PbI3 thin-film solar cells, compared to BZO/F, AZO/PAP(P1.0D0.5) would enable a gain of up to 16.7 and 11.2% in photoelectric conversion efficiency for the 0 and 60° incidence, respectively.
•We examine the effect of price spillover network on firm's stock liquidity.•Firms with higher centrality are suffer from greater price shocks leading to lower stock liquidity.
This article examines ...the effect of the Engle-Granger (E-G) price spillover network characteristics on firm's stock liquidity with a longitudinal dataset of FTSE 350 from 2006 to 2021. We find that the subprime crisis, European debt sovereign crisis, British Brexit and COVID-19 caused dramatic network structure change. We also find that firms with higher centrality are likely to suffer from more or greater price shocks leading to lower stock liquidity. Finally, the robust of our results has also been identified, and a general framework for network characteristics and stock liquidity has been established to some extent.
•A novel life prediction model was developed based on the CMD and fracture mechanics.•Surface-damage-induced lifetime degradation was analyzed quantitatively.•Effects of stress amplitude and exposure ...time on the surface-damage-induced degradation were investigated.•The model was applied for materials with surface hot-corrosion, oxidation and vulcanization.
In this study, a novel life prediction model was proposed for the low-cycle fatigue life degradation induced by surface damage based on continuum damage mechanics and fracture mechanics. Compared to the traditional life prediction model, this model could predict the life of the affected surface areas and combine quantitative analysis and life analysis. Furthermore, the application of this model was also helpful to understand the strength degradation of specimens under different pre-exposure environments. The accuracy of this model was verified via a series of experimental data, including pre-exposure data in the hot-corrosion, static air, and wet H2S environment. The results indicated that a longer pre-exposed time can reduce the fatigue strength of the surface material, thereby degrading the life of specimens.
PDF
