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- 저자 : Qianqian Ma (검색결과 5 건)
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Qianqian Dong,Chengwang Xiong,Chunlei Ma,Huajian Wei 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.6
Extensive efforts have been made in the understanding of the failure characteristics of straight fissure, but the failure patterns of rock mass with intermittent non-straight fissures have not been examined comprehensively. To address this problem, the present study investigated the cracking behaviors of natural marble specimens containing double S-shaped fissures under compression. Seven types of coalescence patterns for S-shaped fissures are classified, two of which are firstly reported and featured by the occurrence of the self-coalescence phenomenon. It is found that the decrease of strength is accompanied by the internal crack at the stage of crack growth and propagation, following the occurrence of the external crack, at relatively large flaw and ligament angle. The numerical simulations with the corresponding parameters were carried out for comparison. This research provides helpful information for understanding the failure modes induced by crack propagation of intermittent double S-shaped fissures.
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Qianqian Shi,Aimin Li,Qing Zhou,Chendong Shuang,Yan Li,Yan Ma 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.6
Carbon/iron composites were prepared from waste cation exchange resin by NaOH activation. The BETsurface areas were over 1200 m2 g-1. The presence of iron led to the formation of new mesopores andmacropores. Activation temperature had a significant impact on the pore size distributions, crystalstructures, and magnetic properties of the carbon composites, and the magnetic properties of thecomposites were related to their crystal structures. The composite synthesized at 800 8C (800ACS-1)could effectively remove diethyl phthalate, bisphenol A, and malachite green from aqueous solutions. 800ACS-1 also exhibited high stability over a wide pH range of 4–11.5.
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Flight and Hover Control System Design for a Mini-quadrotor Based on Multi-sensors
Zhongli Ma,Huixin Li,Yanming Gu,Zuoyong Li,Qianqian Li 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.2
Mini-quadrotor is difficult to control in the air due to its small size and light weight. This paper presentsthe flight and hover control system for a mini-quadrotor, including design and simulation of calculations and controllers. Firstly, the attitude and position of the mini-quadrotor are obtained by distributed multi-sensors. Since attitudecalculation of aircraft needs a number of combined rotations and vectors transformed by rotation, quaternionsare applied to express the attitude model. About error compensation of gyroscope and accelerometer, IMU_Updataalgorithm of Mahony filter are applied and improved to realize data fusion [1]. In order to realize accurate hoveringat certain position, UWB (UltraWideband) are applied to gain positional information of mini-quadrotor and correctthe antenna delay caused sensor error by base station positioning. The discrete Kalman filter of original data is usedto achieve the optimized estimation of the airborne position. Px4flow optical flow sensor is able to gets velocityinformation and avoid the noise problem, which is caused by differential of position data. Then, the mathematicalmodel of a mini-quadrotor’s flight and hover control system can be established. Herein, integral items are solved bythe integral separation and integral limiting to mitigate the serious overshoot and oscillation of the system caused bythe cascade PID. Finally, the simulation of the attitude controller and position controller are applied with the MATLABSimulink library. The simulation result shows that the designed attitude controller and position controller canenable the mini-quadrotor to fly smoothly, move in all directions and hover.
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Overexpression of a maize MYB48 gene confers drought tolerance in transgenic arabidopsis plants
Yan Wang,Qianqian Wang,MingLi Liu,Chen Bo, Xi Wang,Qing Ma,Beijiu Cheng,Ronghao Cai 한국식물학회 2017 Journal of Plant Biology Vol.60 No.6
MYBs are a vital family of transcription factorsthat play critical roles in plant development and stressresponse. However, knowledge concerning the functions ofMYBs in the non-model plants is still limited. In this study,we isolated a R1-type MYB gene from maize (Zea mays L.),designated as ZmMYB48. Quantitative RT-PCR analysisdemonstrated that ZmMYB48 expression was induced bydrought and ABA treatments. Subcellular localization analysisrevealed that ZmMYB48 protein was targeted to the nucleusin tobacco leaf epidermal cells. Transactivation assay in yeastdemonstrated that ZmMYB48 had transcriptional activationability. Heterologous overexpression of ZmMYB48 inArabidopsis remarkably improved plant tolerance to droughtstress, as determined through physiological analyses ofsurvival rate, relative water content, malonaldehyde content,relative electrolyte leakage and proline content. Moreover,overexpression of ZmMYB48 enhanced the expression ofstress/ABA-responsive genes such as P5CS1, RD22, RD29Band ABI1. In addition, ZmMYB48-overexpressing plantsaccumulated higher content of ABA than WT plants underdrought stress. These results demonstrate that ZmMYB48might act as a positive regulator that participates in thedrought stress response through ABA signalling.
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Fuxi Li,Junzhao Ye,Yanhong Sun,Yansong Lin,Tingfeng Wu,Congxiang Shao,Qianqian Ma,Xianhua Liao,Shiting Feng,Bihui Zhong 대한당뇨병학회 2021 Diabetes and Metabolism Journal Vol.45 No.3
Background: Excessive delivery of free fatty acids (FFAs) to the liver promotes steatosis and insulin resistance (IR), with IR defined as reduced glucose uptake, glycogen synthesis and anti-lipolysis stimulated by normal insulin levels. Whether the associations between FFAs and diabetes development differ between patients with and without nonalcoholic fatty liver disease (NAFLD) remains unclear. Methods: Consecutive subjects (2,220 NAFLD subjects and 1,790 non-NAFLD subjects according to ultrasound imaging) were enrolled from the First Affiliated Hospital of Sun Yat-sen University between 2009 and 2019. The homeostasis model assessment of insulin resistance (HOMA-IR) was calculated. Results: There was an approximate J-shaped relationship between FFA levels and HOMA-IR in the NAFLD group. Higher FFA concentration quartiles were associated with higher risks of IR (odds ratio [OR], 9.24; 95% confidence interval [CI], 6.43 to 13.36), prediabetes (OR, 10.48; 95% CI, 5.66 to 19.39), and type 2 diabetes mellitus (T2DM; OR, 19.43; 95% CI, 12.75 to 29.81) in the NAFLD group but not in the non-NAFLD group. The cut-off points for the FFA levels increased in a stepwise manner in discriminating IR, prediabetes and T2DM (573, 697, and 715 μmol/L) in the NAFLD group but not in non-NAFLD individuals. Conclusion: A distinct dose-dependent relationship of FFA levels was found with IR, prediabetes and T2DM in NAFLD patients. Screening serum FFA levels in NAFLD patients would be valuable in preventing diabetes development.
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