共查询到20条相似文献,搜索用时 109 毫秒
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TNNS(真航向导航系统)由MS860接收机、INS及处理数据的PC/104架构的嵌入式工控机构成。针对TNNS推导了INS(惯性导航系统)的误差模型,提出了适合于TNNS的降阶扩展卡尔曼滤波算法组合GPS和INS。系统在东海作了三次海试,软件及滤波算法平台由C/C 编制。海上试验表明,组合滤波后,INS的位置误差由100m降低到40m以下;进行最优化滤波后的航向误差σ由原来的0.105°减小为0.034°,纵横摇的误差也大幅减小。整个海试结果表明,在TNNS中组合GPS/INS采用的降阶扩展卡尔曼滤波算法,大幅提高了系统精度和可靠性。 相似文献
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本文给出了用分段霍普金森压杆进行材料动态力学性能实验的一个数据采集及处理系统,实验中由应变传感器得到的信号由2MHz的A/D变换器记录下来,并存入磁带机,然后把信号通过A/D接口送入微处理机,最后经过计算机处理给出数据表形式的打印结果,并直接由绘图机画出实验材料的~~关系曲线。这种方法比过去所用的示波器照相法要快得多,而且提高了精度。 相似文献
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用XPS研究了固体润滑剂,主要是探讨了其失效过程的化学变化。Atkinson等进行了二硫化钼和氟化石墨的研究。 将二硫化钼作成2微米厚的膜在平面-平面接触的试验机上进行试验,摩擦系数达到0.2时停止试验。根据试样的XPS分析结果,观测到钼、硫减少,氧、铁增加,钼、硫都有氧化的现象。钼由Ⅳ价变成Ⅵ价,硫由Ⅱ价变成零价和Ⅵ价。由钼的化学位移与它的化学结合状态可以认为,二硫化钼的失效是由于氧化的缘故。 相似文献
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旋转调制技术在调制惯性器件常值误差,有效提高惯导系统长航时导航精度的同时,也引入了由系统旋转而造成的速度误差以旋转周期和旋转周期二倍频波动,这种波动对以速度为匹配量的传递对准有一定的影响。从旋转调制系统的误差特性出发,分析了旋转调制对以速度为匹配量传递对准的有利和不利影响,并针对不同的旋转调制周期进行了仿真验证,仿真结果表明当旋转周期远大于舒勒周期时,旋转调制引起的不利和有利影响都很小,可忽略不计;当旋转周期远小于舒勒周期时,旋转调制可提高子惯导的方位对准精度,但延长了系统的传递对准时间。例如,当旋转周期为3(°)/s时,水平对准时间由3 min延长到4 min,而对准精度由1.2′提高到0.2′;方位对准时间由10 min延长到16 min,而对准精度由2.2′提高到0.4′。 相似文献
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A class of N-parameter Gaussian processes are introduced, which are more general than the N-parameter Wiener process. The definition of the set generated by exceptional oscillations of a class of these processes is given, and then the Hausdorff dimension of this set is defined. The Hausdorff dimensions of these processes are studied and an exact representative for them is given, which is similar to that for the two-parameter Wiener process by Zacharie (2001). Moreover, the time set considered is a hyperrectangle which is more general than a hyper-square used by Zacharie (2001). For this more general case, a Fernique-type inequality is established and then using this inequality and the ments is required for showing the representative of the Hausdorff dimension by Zacharie (2001). This property is absent for the processes introduced here, so we have to find a different way. 相似文献
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塑料表面改性对其摩擦学性能影响 总被引:4,自引:1,他引:3
论述了采用离子注入、气相沉积、激光熔敷和等离子喷涂等表面改善塑料摩擦学性能方面的研究现状和进展,分析了塑料表面离子注入改性的机理,指出采用合适的表面改性工艺可有效地提高塑料表面的硬度并进而提高其耐磨性,从而进一步延长塑料的使用寿命 ,扩大其段А 相似文献
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数字锁相速率系统实质是一个非线性系统。确定其最高速率极限是设计者十分关心的问
题。本文采用求锁相环非线性系统极限环频率的方法确定了系统的速率极限,并给出了计算公
式。用该方法对某转台速率系统进行了计算,结果证明了此方法的有效性。 相似文献
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The aim of this work is to show first, how the springback of a steel sheet drawn part is affected by the stiffness degradation,
as it results from the damage evolved during forming process, and second, to build a respective modeling approach to take
this degradation into account. For the consideration of the orthotropic elastic properties degradation we develop an approach,
based on the Mori-Tanaka theory, where damage is considered by inclusion of ellipsoidal cavities. The respective void shape
evolution is proposed to be identified with the measurements of elastic modulus in two perpendicular directions during the
uniaxial tensile test of a flat specimen at different loading stages. The proposed approach is coupled with the Gurson-Tvergaard-Needleman
(GTN) plastic potential, though it could be substituted by almost any other continuum damage model. At the end the presented
approach is experimentally validated by a simple springback test, developed by authors. A very good agreement between by calculation
predicted and measured springback amount is observed. 相似文献
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An explicit algebraic model for the fluctuating pressure–strain rate correlations of turbulence is developed by the use of representation theorems for tensor-valued isotropic tensors, and by invoking the principle of objectivity. The resulting model differs from others by the absence of the vorticity tensor from its formulation. The new model is calibrated by reference to data from homogeneous shear flows, and its potential as a practical tool for the analysis of turbulent flows is demonstrated by numerical simulations of a benchmark two-dimensional shear layer. 相似文献
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本文利用计算机产生拟湍流脉动信号,将数据进行频谱分析和能谱分析,发现湍流中相干结构不仅包合低频成分还包含一定数量高频成分,因而简单地认为湍流中低频部分是相干结构而高频部分是小尺度脉动,来确定相干结构能量在湍流中所占成分是不科学的;本文还将得到的数据用几种条件采样方法检测相干结构数量和位置,以此判断检测方法的优劣,发现就这类信号而言MU—LEVEL法要比VITA法准确性要高一些。 相似文献