The joint effect of different concentration of Cd<SUP>2+</SUP> and ionic liquid on the growth of wheat seedlings

Zhonglin Chen,Qian Zhou,Feng Leng,Bing Dai,Xueyang Zhao,Weichen Zhang,Neng Liu,Wei Guan,Kui Liu 대한환경공학회 2017 Environmental Engineering Research Vol.22 No.3

The joint effect of different concentrations (0.05-0.375 mmol/L) of Cd<SUP>2+</SUP> and various concentrations (50-400 mg/L) of [C3mim][OAc] on the growth and physiology of wheat seedlings were investigated. The toxicity of Cd<SUP>2+</SUP> could be significantly reduced by lower concentrations (50-200 mg/L) of [C3mim][OAc]. With higher concentration (≥ 300 mg/L) of [C3mim][OAc], the reduction became less, and compared to Cd<SUP>2+</SUP> stress only, the toxicity of 400 mg/L [C3mim][OAc] increased. As for different Cd<SUP>2+</SUP> concentrations, the optimal reduction depends on the balance between the exact concentration of Cd<SUP>2+</SUP> and [C3mim][OAc]: With low Cd<SUP>2+</SUP> concentration (0.05-0.250 mmol/L) requiring 50 mg/L [C3mim][OAc], it could reach a dynamic equilibrium, while high Cd<SUP>2+</SUP> concentration (0.375 mmol/L) requiring 100 mg/L [C3mim][OAc]. The growth and physiological indexes of wheat seedlings show a decrease in toxicity compared to the Cd alone treatment, when the dynamic equilibrium is reached. The concentration of Cd<SUP>2+</SUP> in leaf tissues showed that low concentration (50-200 mg/L) of [C3mim][OAc] can reduce the toxicity of Cd<SUP>2+</SUP> (0.05-0.375 mmol/L) by decreasing the level of Cd<SUP>2+</SUP> concentration in the tissues, whereas the higher concentration (≥ 300 mg/L) of [C3mim][OAc] can increase the concentration of Cd<SUP>2+</SUP>.

Investigation on the Dynamic Response of a Wide-Chord Fan Blade Under Ground Vortex Ingestion

Zhonglin Wang,Yong Chen,Hua Ouyang,Anjenq Wang 한국항공우주학회 2019 International Journal of Aeronautical and Space Sc Vol.20 No.2

This paper presents a computational study of the dynamic response of the fan blade owing to the excitations from the ingested ground vortex when the turbofan engine is operating on the ground or during the takeoff run. Firstly a numerical method consisting of static, modal and transient analyses is proposed to investigate the dynamic vibration characteristics of a fan blade model with pre-vibration. Modal analysis is conducted to find the critical speed of blade resonances, and the intersection of the fourth engine order and the second bending mode is identified for the study. Secondly, transient analyses of the vortex ingestion are carried out to investigate the resulting blade responses. Various parameters, including different ingestion timings, rotating speeds, ingestion positions and modes of pre-vibration are discussed. Results of dynamic displacement and stress illustrate that the effect of the ingested vortex is significant. Especially when the fan blade is working at the critical speed where engine orders intersect with the dynamic frequencies, the stress is amplified by 276.6% and the displacement is amplified by 156.7%. This paper demonstrates a preliminary method to connect the flow excitations of the ground-ingested vortex and the fan blade vibration characteristics, and provides a helpful reference to the further study of the fan blade vibration.

Can It Get Out of Predicament? Japan's Policy towards DPRK Nuclear Issue

Zhonglin Li,Wei Chen,Qisong He 한국학술연구원 2023 Korea Observer Vol.54 No.2

This study aims to examine Japan's policy towards DPRK nuclear issue. It summarizes current Japan's policy pattern towards DPRK nuclear issue. Japan's entrenched marginal position in the Northeast Asian security architecture fundamentally shaped the outward appearance of Japan's policy towards the DPRK nuclear issue. However, there is still some room for Japan to play out. Some factors determine why current Japan's policy towards DPRK nuclear issue is ineffective. These factors include the following: Japan did not handle its relations with its neighbors China, South Korea, and Russia well, but instead further deteriorated the three pairs of bilateral relations; China, Russia, and North Korea constitute a potential alliance, further increasing the pressure on Japan; Japan's domestic public opinion abducted the government's DPRK policy; The last assumption is that current Japan is a country without nuclear weapons. Japan's willingness and ability to deal with the above issues will determine the future trajectory and effectiveness of its policy towards the DPRK nuclear issue.

HCF Weak Link Optimization for Wide-Chord Fan Blades Based on Circumferential Stacking Line Design

Yong Chen,Zhonglin Wang,Xiaopu Zhang 한국항공우주학회 2021 International Journal of Aeronautical and Space Sc Vol.22 No.4

This paper describes the combination of a Kriging surrogate model with a micro-genetic algorithm for studying the influence of circumferential perturbations from the stack line on the high-cycle fatigue (HCF) weak link of a fan blade in a high-bypass-ratio turbofan engine. Based on the circumferential perturbations of the fan blade stack line, an automated system is developed for the parameterized modeling and meshing of the blade, and an integral platform is established for parameterized modeling, finite-element simulation, and optimization. The static stress, index of strain energy density, and vibratory stress margin of the 1st flex mode are set as the objective functions for the optimization of a fan blade. The results show that the optimized blade has three areas of low static stress, unlike the single “bull’s eye” distribution of the baseline blade. Optimization reduces the maximum static stress by 5.87% and the strain energy density index by 0.77%, while increasing the vibratory stress margin under the same dynamic load by 9.51%. The natural frequencies, mode shapes, resonance margins, and aerodynamic parameters exhibit no significant changes, which illustrates that the optimization method can improve the static stress and vibratory stress distribution of the fan blade without negatively influencing the other vibration and aerodynamic characteristics. The proposed method is an effective means of fan blade design optimization, and could be applied alongside other design variables and objective functions, such as the swept and skewed configuration of the stack line and twist angle of the blade, to optimize the vibration characteristics and aero-elastic performance.

Simulation analysis and evaluation of decontamination effect of different abrasive jet process parameters on radioactively contaminated metal

Zhong Lin,Deng Jian,Zuo Zhe-wen,Huang Can-yu,Chen Bo,Lei Lin,Lei Ze-yong,Lei Jie-heng,Zhao Mu,Hua Yun-fei 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.11

A new method of numerical simulating prediction and decontamination effect evaluation for abrasive jet decontamination to radioactively contaminated metal is proposed. Based on the Computational Fluid Dynamics and Discrete Element Model (CFD-DEM) coupled simulation model, the motion patterns and distribution of abrasives can be predicted, and the decontamination effect can be evaluated by image processing and recognition technology. The impact of three key parameters (impact distance, inlet pressure, abrasive mass flow rate) on the decontamination effect is revealed. Moreover, here are experiments of reliability verification to decontamination effect and numerical simulation methods that has been conducted. The results show that: 60Co and other homogeneous solid solution radioactive pollutants can be removed by abrasive jet, and the average removal rate of Co exceeds 80%. It is reliable for the proposed numerical simulation and evaluation method because of the well goodness of fit between predicted value and actual values: The predicted values and actual values of the abrasive distribution diameter are Ф57 and Ф55; the total coverage rate is 26.42% and 23.50%; the average impact velocity is 81.73 m/s and 78.00 m/s. Further analysis shows that the impact distance has a significant impact on the distribution of abrasive particles on the target surface, the coverage rate of the core area increases at first, and then decreases with the increase of the impact distance of the nozzle, which reach a maximum of 14.44% at 300 mm. It is recommended to set the impact distance around 300 mm, because at this time the core area coverage of the abrasive is the largest and the impact velocity is stable at the highest speed of 81.94 m/s. The impact of the nozzle inlet pressure on the decontamination effect mainly affects the impact kinetic energy of the abrasive and has little impact on the distribution. The greater the inlet pressure, the greater the impact kinetic energy, and the stronger the decontamination ability of the abrasive. But in return, the energy consumption is higher, too. For the decontamination of radioactively contaminated metals, it is recommended to set the inlet pressure of the nozzle at around 0.6 MPa. Because most of the Co elements can be removed under this pressure. Increasing the mass and flow of abrasives appropriately can enhance the decontamination effectiveness. The total mass of abrasives per unit decontamination area is suggested to be 50 g because the core area coverage rate of the abrasive is relatively large under this condition; and the nozzle wear extent is acceptable