机械振动特征分析中的信号处理技术与微机特征分析系统

文中指出抑制阶比混迭和泄漏是建立一套完整的微机特征分析系统中需要解决的二个关键的信号处理问题。提出了阶比滤波器是抑制阶比混迭有效和实用的方法;并研制频率比合成器以抑制泄漏。介绍了由频率比合成器、阶比滤波器、TMS32010数据采集装置、主机和绘图仪所组成的微机特征分析系统。最后给出了该微机特征分析系统对轴承进行故障诊断的结果。     

带噪声的 AR 模型的参数估计及定阶

本文讨论了带噪声情形下 AR 模型的参数估计及定阶问题,还给出了噪声模型的参数估计,并证明了它们的强相容性。     

提速列车车厢减小空气阻力风洞实验研究

列车提速使得其空气阻力明显增大。为了减小空气阻力，列车车厢气动外形的研究变得愈加重要。在低速风洞中获得的实验结果表明，对现型列车车厢局部外形稍加改善，就能使得其空气阻力大为降低。这是实现我国列车提速最为有效的途径之一。     

Numerical investigation of dynamic interaction with projectile and harmonic behaviour for T-finned machine gun barrels

Machine gun barrels differ from their rifle counterparts in terms of profile. To support high rates of sustained fire, machine gun barrels are made thicker in order to dissipate more heat and maintain their flexural rigidity and thus accuracy, but on other hand they also contribute in weight addition to weapon. This investigation deals with comparison between a conventional machine gun barrel and an improved innovative design having T-fins, both having same weight and chambered in 5.56 × 45 NATO ammunition, to compare their structural and harmonic characteristics which were parameterized by factors such as modal spectrum, directional deformation at muzzle ends during a single shot fire and harmonic behaviour at corresponding range of exciting frequencies. The solid models of both the barrels having same weight, were created using Solidworks. The continuous input data functions were generated by MATLAB using the field tested discreet data points. The generated velocity-distance functions were converted into time dependent functions using integration algorithms to calculate transient parameters such as time steps, excitation frequency range, angle of rotation of projectile and its angular velocity. The dynamic condition simulated the varying nature of forces due to eccentricity in projectile and this data was fed to a time step study using ANSYS transient structural work bench followed by modal and harmonic analysis. The results showed a significant reduction in muzzle end deformation which thus proved that the T-finned barrel, although had same weight as that of the conventional one, but had better structural and harmonic characteristics, and hence it would inherit better firing accuracy.     

一类非正态误差下的AR模型定阶研究

对一类非正态误差的AR模型,在待定阶数P的情况下,给出误差项中未知实函数依概率有界的定理,可把非正态误差转化为正态情况。最后运用正态误差下AR模型的方法确定阶数和参数,并给出一个算例。     

Dynamic capacity reservation and due date quoting in a make‐to‐order system

We consider a make‐to‐order manufacturer facing random demand from two classes of customers. We develop an integrated model for reserving capacity in anticipation of future order arrivals from high priority customers and setting due dates for incoming orders. Our research exhibits two distinct features: (1) we explicitly model the manufacturer's uncertainty about the customers' due date preferences for future orders; and (2) we utilize a service level measure for reserving capacity rather than estimating short and long term implications of due date quoting with a penalty cost function. We identify an interesting effect (“t‐pooling”) that arises when the (partial) knowledge of customer due date preferences is utilized in making capacity reservation and order allocation decisions. We characterize the relationship between the customer due date preferences and the required reservation quantities and show that not considering the t‐pooling effect (as done in traditional capacity and inventory rationing literature) leads to excessive capacity reservations. Numerical analyses are conducted to investigate the behavior and performance of our capacity reservation and due date quoting approach in a dynamic setting with multiple planning horizons and roll‐overs. One interesting and seemingly counterintuitive finding of our analyses is that under certain conditions reserving capacity for high priority customers not only improves high priority fulfillment, but also increases the overall system fill rate. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008     

适用于认知无线传感器网络的高效频谱分配方法

广泛工作在ISM(Industrial,Scientific and Medical)频段的无线传感器网络面临严重的频谱稀缺问题。在无线通信中,动态频谱分配被认为是提高频谱效能的重要途径。针对典型集中式管理的认知无线传感器网络设计了基于图着色结合负载强度的高效频谱分配算法。首先在协议干扰模型下确保频谱资源在空间上充分利用,随后综合考虑节点负载强度与公平性建立优化模型并按照乘子法加拟牛顿法框架求解最优值。仿真实验表明算法与固定频谱分配方式和传统自适应频谱分配算法相比,在系统吞吐量和节点缓冲区队列长度两个关键性能指标上具有显著优势。     

ENO格式应用分析

对一类高阶、高分辨率的ENO格式进行了较为详细的讨论。通过一些典型算例的应用和同常用TVD类型格式的比较 ,说明了在计算中采用高阶格式分辨复杂流动结构的优越性。在对格式应用分析的基础上 ,指出了格式应用中需注意的问题。通过定量分析说明 ,高阶ENO格式在计算中 ,不但能够减少网格规模 ,而且能够明显提高计算物理量 ,特别是其导数的计算精度     

一种适用任意平面多边形的三角剖分算法

针对基于凹凸顶点判定的三角剖分算法适用范围有限的缺点 ,提出了将凹凸顶点判定与连接多边形内外边界相结合的适用任意平面多边形的三角剖分算法 GTP( General Triangulation of Polygons)。GTP计算速度快、适用范围广的良好特点已在应用中得到证实