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在文献中,首次用函数优选法推导出普通(直流)离子渗氮层长大动力学的教学模式,用仿型积分法推导出了各相层氮浓度分布函数。但是,不同材料、不同渗氮条件下不同渗氮相中的氮扩散系数不同,目前这方面的数据十分缺乏。针对这一实际情况,并考虑迄今尚未见到有关工频交流离子渗氮层长大动力学及渗层氮浓度分布函数的报导,本文用回归分析试验和计算方法求得工频交流离子渗氮层长大动力学的数学模式,利用这些 相似文献
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<正> 一、引言 飞行器气动参数辨识作为系统辨识理论在航空、宇航领域的应用分支,在一些发达国 家受到了相当的重视,并且从70年代以来已形成了气动参数辨识软件包,不仅缩短了飞行器的设计、改型及性能分析的周期,并且还具有靠风洞实验或理论分析所不具备的优点。目前飞行器的气动参数辨识虽已有很大发展,但是对有控飞行器的闭环辨识问题仍未解决,分析传感器非线性因素对气动参数辨识结果的影响也不够深入。本文使用极大似然法,结合某有控飞行器的全弹道仿真数据,研究了在闭环飞行状态下进行气动参数辨识所存在的问题,分析了传感器的非线性因素对气动参数辨识的影响。 相似文献
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Wang Yongzhang Ma Xiongbo Chen Liangji Han Zhenyu 《中国航空学报》2007,20(4):362-369
By making use of the advantages of non-uniform rational B-spline (NURBS) curves to represent spatial curves, an instruction format with double NURBS curves suitable for 5-axis coordinated real-time interpolation is presented to replace the current 5-axis coordinated linear interpolation method defective in low-speed, low-accuracy and enormous numerical control (NC) files in sculptured surface machining. A generation procedure of the NC files with the presented format is introduced and the method to realize the interpolation in an open computer numerical control (CNC) system is developed by ourselves. These illustrated the feasibility of the proposed method and its capability of avoiding all the shortages of 5-axis linear interpolation method. 相似文献
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直纹面叶轮刀具轨迹规划的研究(英文) 总被引:2,自引:1,他引:1
Liang Quan Wang Yongzhang Fu Hongya Han Zhenyu School of Mechatronics Engineering Harbin Institute of Technology Harbin China 《中国航空学报》2008,21(5):462-471
At present, most commercial computer-aided manufacturing (CAM) systems are deficient in efficiency and performances on generating tool path during machining impellers. To solve the problem, this article develops a special software to plan cutting path for ruled surface impellers. An approximation algorithm to generate cutting path for machining integral ruled surface impellers is proposed. By fitting sampling data points of an impeller blade into a curve, a model of ruled surface blade of an impeller is built up. Furthermore, by calculating the points where the cutter axis vector intersects the free-form hub surface of an impeller, problems about, for instance, the ambiguity in calculation and machining the wide blade surface with a short flute cutter are solved. Finally, an integral impeller cutting path is planned by way of an integrated cutter location control algorithm. Simulation and machining tests with an impeller are performed on a 5-axis computer numerically controlled (CNC) mill machine, which shows the feasibility of the proposed algorithm. 相似文献