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RISS 인기검색어
- 검색키워드
- 저자 : Qiangqiang Zhao (검색결과 4 건)
- 무료
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Qiangqiang Zhao,Junkang Guo,Jun Hong 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.7
The assembly process for planar closed-loop mechanisms is full of complexity and uncertainty due to joint clearance, link coupling and probable redundant constraint. In order to ensure assembly precision, an algorithm of predicting accuracy for planar closed-loop mechanisms in view of joint clearance and redundant constraint is proposed. Firstly by analyzing the assembly process of a planar fivebar closed-loop mechanism, three components of single-fixed, two-connected and redundant-inserted links are proposed to describe the assembly process of arbitrary planar closed-loop mechanisms which is regarded as successive stacking of those components. Then error models of those components are established based on the linear kinematics and principle of virtual work. Subsequently, an algorithm of precision prediction for planar closed-loop mechanisms is constructed by combining those error models. Finally the extendible support structure of the SAR antenna is used as the numerical example to verify the validity and generality of the proposed algorithm.
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Xiaokun Hu,Qiangqiang Zhao,Yitao Yang,Shaoke Wan,Yanhui Sun,Jun Hong 한국CDE학회 2023 Journal of computational design and engineering Vol.10 No.5
The rotation accuracy of a machine tool spindle is essential for ensuring the machining precision. Due to the existence of manufacturing and assembly errors, the rotation accuracy of the spindle will be inevitably impacted and degraded. Therefore, to reduce the influence of the errors and improve the work performance, this paper focuses on accuracy analysis for the spindle and a novel optimization-oriented skin model shape method to tackle this highly complex problem. First, a structural analysis of the spindle is carried out to elaborate the intractable full parallel collections in the assembly. Then, based on the iterative closest point method, the deviation propagation of the spindle considering complex full parallel collections is transformed into an optimization problem, in which the skin model shapes and small displacement torsor are utilized to represent the form and pose errors of the part, respectively. By solving the optimization problem, assembly accuracy analysis for the spindle in terms of full parallel connections and form errors is accordingly achieved. On this basis, the tolerance analysis model of the spindle is also comprehensively established by employing the corresponding error simulation. Finally, measurement experiments are conducted to validate the effectiveness of the proposed method. The experiments show the predicted rotation runout and tolerance magnitude are close to the testing results, therefore indicating the proposed method can provide effective accuracy analysis for spindles.
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Han Tian,Baojiang Liu,Xia Dong,Qiangqiang Zhao,Jinxin He 한국섬유공학회 2020 Fibers and polymers Vol.21 No.12
In this study, a new reactive surfactant was synthesized from cyanuric chloride and Jeffamine ED-600 or ED-2003,and then applied to the pre-reduced wool fabric in saturated neutral salt solution at low temperature. This treatment conditioninhibited the wool swelling, making the surfactant mainly covalently bond on the scales of wool. The structure of surfactantwas confirmed by 13C NMR, and the modified wool fabrics were characterized by FTIR-ATR, XPS, and SEM after carefullywashing with acetone and water. The wettability, liquid transport ability, antistatic and mechanical properties of the modifiedwool fabrics were also investigated. The results suggested that this modification method could significantly improve thehydrophilicity of wool surface, enhance the transport ability of liquid through the fabric and increase the antistatic propertiesof the fabric under low humidity conditions. Importantly, the modified fabric has robust washing fastness, with no seriousdamage to wool.
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Overexpression of IbMPK3 increases low-temperature tolerance in transgenic sweetpotato
Jin Rong,Kim Ho Soo,Yu Tao,Liu Ming,Yu Wenhui,Zhao Peng,Zhang Aijun,Zhang Qiangqiang,Liu Yaju,Cao Qinghe,Kwak Sang-Soo,Tang Zhonghou 한국식물생명공학회 2022 Plant biotechnology reports Vol.16 No.1
Sweetpotato is an important crop that is very sensitive to low temperatures. Mitogen-activated protein kinase (MAPK) is involved in plant growth and development and is responsive to many environmental stresses. IbMPK3 is strongly regulated by low-temperature stress. We studied the function of IbMPK3 and how it may enhance the adaptability of sweetpotato plants to low-temperature stress. Transgenic sweetpotato plants overexpressing IbMPK3 were generated, and three trans- genic lines with the highest expression level of IbMPK3 were used for low-temperature tests. Transgenic plants exposed to low-temperature stress had less damage associated with higher photosynthesis efficiency and less cell membrane damage. IbMPK3-overexpressing transgenic plants could modulate reactive oxygen species (ROS) metabolism with lower levels of O2− and H2O2 accumulation and higher enzymatic activities than WT plants. Transcript expression levels of some ROS- related genes (IbCAT, IbCu-ZnSOD, and IbCAT) and stress-responsive genes (IbP3B and IbCOR27) were significantly upregulated in transgenic plants compared to WT. These results indicate that IbMPK3 has an important role in sweetpotato response to low temperatures.
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