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基于先进拉挤工艺的帽形长桁预成型模具的优化重构
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作者 陈博毅 齐俊伟 +1 位作者 王跃全 石甲琪 《复合材料科学与工程》 CAS 北大核心 2023年第3期59-67,共9页
对帽形长桁先进拉挤(Advanced Pultrusion, ADP)原理样机制备预制体试验进行了研究。预制体成型质量的影响因素有预成型模具曲面外形、预成型温度、张力大小等,其中模具曲面外形设计不合理会影响层合板温度均匀性及张力传递。结合M21预... 对帽形长桁先进拉挤(Advanced Pultrusion, ADP)原理样机制备预制体试验进行了研究。预制体成型质量的影响因素有预成型模具曲面外形、预成型温度、张力大小等,其中模具曲面外形设计不合理会影响层合板温度均匀性及张力传递。结合M21预浸料材料属性在ABAQUS中建立模型模拟预成型过程,层合板变形模拟结果与实际试验基本吻合,验证了弹性参数及边界条件的可靠性。将变形后的预浸料层合板节点坐标通过CATIA文件夹内GSD_PointSpline-LoftFrom-Excel宏命令导入CATIA,运用创成式外形设计重构模具曲面外形。模具优化后重复预成型模拟试验,研究结果表明运用此方法重构模具曲面外形改善了层合板与模具之间的贴附性,架空间隙包络体积减小至优化前间隙体积的2.6%,从而可提高预成型过程中层合板的温度均匀性,便于预浸料层间滑移运动,减少预制体缺陷产生。 展开更多
关键词 复合材料 先进拉挤 帽形长桁 浸料 预成型模具 贴附性
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对锻件预成型模具进行模拟及优化研究 被引量:1
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作者 张烁 《军民两用技术与产品》 2018年第8期188-189,共2页
本文对金属材料在锻造成型过程中存在的不足情况进行探讨.以工字型锻件作为案例,对其形状均匀化作为优化目标.主要是对角度大小和半径尺寸进行优化设计,对优化后的两种预锻模形状都可以充满,使相关材料可以达到充满终锻模型腔.并且使得... 本文对金属材料在锻造成型过程中存在的不足情况进行探讨.以工字型锻件作为案例,对其形状均匀化作为优化目标.主要是对角度大小和半径尺寸进行优化设计,对优化后的两种预锻模形状都可以充满,使相关材料可以达到充满终锻模型腔.并且使得预锻模形状优化后的飞边尺寸均匀化目标函数值可以达到最小. 展开更多
关键词 锻件预成型模具 模具设计 参数优化
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杆状紧固件预成形模设计
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作者 杨立慧 《紧固件技术》 1995年第4期20-25,共6页
本文根据材料力学的压杆失稳条件,计算出锥形模腔大端直径的理论极限值,并分别给出了不同长径比的预成形模的尺寸设计和结构设计。
关键词 紧固件 预成型模具 设计 螺栓
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Short Group Signatures with Efficient Concurrent Join
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作者 CHEN Hefeng MA Wenping +1 位作者 ZHANG Cheng SUN Changxia 《China Communications》 SCIE CSCD 2014年第11期90-99,共10页
Group signature schemes are fundamental cryptographic tools. A group signature scheme allows members of a group to anonymously sign misuse, the anonymity messages. To counter can be revoked by the group manager. The g... Group signature schemes are fundamental cryptographic tools. A group signature scheme allows members of a group to anonymously sign misuse, the anonymity messages. To counter can be revoked by the group manager. The group joining operation is a critical component of group signature scheme, the framing attack can be prevented by group joining processes. This paper presents an efficient group signature scheme with a simple joining protocol that is based on a "single message and signature response" interaction between the prospective user and the group manager. The security of our group signature is based on the Discrete Logarithm assumption and Decisional Linear Diffie- Hellman assumption. The formal security proof of our scheme is given in the random oracle model. Our scheme is also a very efficient short group signature scheme with efficient concurrent join. 展开更多
关键词 group signature scheme random oracle model discrete logarithm assumption decisional linear diffie-hellman assumption
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Application of Extreme Value Theory to Generation and Analysis of Pseudorandom Samples
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作者 Svitlana Trukhan Petro Bidyuk 《Journal of Mathematics and System Science》 2016年第4期129-138,共10页
The article deals with the methodology of pseudorandom data analysis. As a mathematical tool for carrying out the research the extreme value theory was used that creates one of the directions in mathematical statistic... The article deals with the methodology of pseudorandom data analysis. As a mathematical tool for carrying out the research the extreme value theory was used that creates one of the directions in mathematical statistics, and is related to investigating the extreme deviations from the median values in probability distributions. Also, the methods for estimating unknown parameters and algorithm of random-number generation are discussed. The models of treatment the extreme values are constructed which are based on machine generated sample and approach is proposed for their future application for constructing forecasting models. 展开更多
关键词 Extreme value theory extreme value threshold simulation and modeling maximum likelihood estimator pseudorandomsample generation.
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