圆度误差的一种微机图像测量法

将圆度误差测量的影像法与最小二乘圆法相结合，利用多媒体图像处理技术，设计了一种圆度误差的微机自动测量系统，实现了非接触、远距离快速测量，提高了测量精确度，为某些特殊工件的测量提供了一套实用的测量方法。     

大型工件平面度平行度垂直度误差计算与评定方法

提出了一种实用的大型工件平面度、平行度、垂直度误差的计算与评定方法。这种方法适用于各种不规则、不连续的测量表面。评定程序采用最小二乘和最小条件法，搜素速度快，评定结果精度高。     

平面度误差的不确定度估计方法及取样点数量的确定

主要阐述在工程测量方案设计阶段,如何采用最小二乘法估算被测要素平面度误差的不确定度和如何确定合理的采样点数,即测量设备的单点坐标不确定度已知时,采用理想点坐标估算法,计算不定乘数系数,继而获得被测要素的采样点数量及其最小二乘法平面度误差的测量不确定度.     

平面度的在线检测及补偿方法的研究

叙述运用四测头进行在线测量，采用最小二乘逐次两点法将工件形状误差和导轨运动副误差分离出来，采用电致伸缩陶瓷元件设计了一套补偿用微量位移装置，根据分离出来的导轨运动副误差，由FAGOR8025M控制器产生控制电压控制砂轮进给的位移量，进行在线补偿加工。分离平面度重复精度优于4％，微量进给装置的位移分辨率可达0.01μm。     

激光干涉法近场扫描架平面度高精度测量及误差分析

根据近场扫描架的结构和运动特点,运用非封闭网格法布线,通过双频激光干涉仪及其直线度附件来采集各条线在Z向的直线度,用最小二乘法求出扫描架X轴和Y轴所走轨迹扫描而成平面的平面度,并分析了影响直线度测量的误差因素。     

圆度误差的精密测量与微机评定

本文介绍了用通用计量器具组合系统进行圆度误差的精密测量及利用微机进行误差分离和数据处理的方法.该方法用最小二乘圆法和最小区域法进行误差评定,可得到与圆度仪相近的测量精度,适用于没有圆度仪的中、小企业.     

位置度测量最小二乘评定

就测量中无中心基准和无角向要求的位置评定问题，运用最小二乘法则对测量数据进行了误差分离优化评定，使此类位置度评定的稳定性和一致性得到改善。     

平面形状误差分离方法的比较分析

就十种典型的精密平面形状误差测量－分离方法的权函数及其零点，作了分析比较。按形状误差谐波抑制最小准则，论证了五点式正交逐次三点法、九点式正交逐次三点法、复合三点法、不对称二维混合法和不对称四点法优于其他方法，不对称四点法则较为理想。     

节距法测量直线度与平面度时桥板定位误差的研究

对目前使用的桥板测量中的定位误差进行了论述，阐明了改进桥板结构、采取必要措施是减小桥板定位误差的有效途径。它有益于提高节距法测量直线度与平面度的准确度，值得重视。     

平板平面度测量不确定度分析及测量标准选择

对用电子水平仪检定平板平面度测量结果的不确定度进行了分析评定,通过将测量结果不确定度与平板平面度最大允许误差进行分析比较,提出了不同于JJG-2005《平板检定规程》选择平板平面度测量标准器的方法.     

Coronal Hole Boundaries and their Interactions with Adjacent Regions

Coronal hole boundaries are the interfaces between regions where the coronal magnetic field contains a significant component which is open into the heliosphere and regions where the field is primarily closed. It is pointed out that there are constraints on the magnetic field which opens into the heliosphere that must be satisfied in the corona: it must come into pressure equilibrium in the high corona, and the component of the field which connects to the polar regions of the Sun must differentially rotate. A model is presented in which satisfying these constraints determines which field lines are open and which are closed, and thus where the polar coronal hole boundaries occur. Some of the consequences of this model are discussed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Optimal sensor selection strategy for discrete-time stateestimators

A novel sensor selection strategy is introduced, which can be implemented on-line in time-varying discrete-time system. We consider a case in which several measurement subsystem are available, each of which may be used to drive a state estimation algorithm. However, due to practical implementation constraints (such as the ability of the on-board computer to process the acquired data), only one of these subsystems can actually by utilized at a measurement update. An algorithm is needed, by which the optimal measurement subsystem to be used is selected at each sensor selection epoch. The approach described is based on using the square root V-Lambda information filter as the underlying state estimation algorithm. This algorithm continuously provides its user with the spectral factors of the estimation error covariance matrix, which are used in this work as the basis for an on-line decision procedure by which the optimal measurement strategy is derived. At each sensor selection epoch, a measurement subsystem is selected, which contributes the largest amount of information along the principal state space direction associated with the largest current estimation error. A numerical example is presented, which demonstrates the performance of the new algorithm. The state estimation problem is solved for a third-order time-varying system equipped with three measurement subsystem, only one of which can be used at a measurement update. It is shown that the optimal measurement strategy algorithm enhances the estimator by substantially reducing the maximal estimation error     

柱塞泵热力学建模与仿真

针对航空行业广泛应用的柱塞泵的热力学特性,提出了一种分析和建模的方法.应用能量守恒定律推导并建立了集中参数的航空柱塞泵的热力学模型,并针对柱塞泵的内部结构进行了较详细的传热分析.将此建模和分析的方法应用于包含航空柱塞泵的一个典型液压回路.通过对航空柱塞泵的热力学实验与仿真结果的比较证明了建模方法的有效性.     

高温合金过滤中的界面问题研究

  过滤器吸附固态夹杂须满足两个条件:一是控制熔体的流动状态,使固态夹杂与过滤器相接触;二是熔体、过滤器及固态夹杂之间满足一定的界面能条件,使固态夹杂被过滤器吸附捕获,然后在高温下依靠热能将固态夹杂与过滤器烧结在一起。因此过滤器去除固态夹杂存在着三种机制;机械拦截机制、流体动力学机制及热力学机制。     

加筋结构中筋条有限元模型研究

 本文提出板杆组合元模型在抗拉及板面内抗弯刚度上均达到与实际筋条相等。该模型不仅是检验各种近似解的工具,而且,可在工程上推广应用。 1.筋条抗拉刚度分析 作如下基本假设:（1）平面应力、线弹性Ⅰ型断裂问题;（2）板的中面与筋条铆钉孔所在缘条中面重合,铆钉力在这个面愉;（3）钉孔仪是一点,铆钉力是作用在该点上的一个集中力;（4）忽略筋条与板间的摩擦力。以机翼下壁板为例进行分析(图     

反导导弹垂直发射初段控制设计初探

以国外某先进反导导弹为研究对象，探讨了反导导弹在空气动力舵快速响应及较高出速速度条件下，快速准确地完成初始段转弯，瞄准任务的垂直发射技术的理论与工程方法，提出了一种基于轨道控制力理论的反导导弹垂直发射初段控制最优化方法及一种在工程上较为实用的导弹飞行冲角变化函数，此外，还提出了一种跨音速S状程序转弯飞行的新方法。     

Optimum detection and location estimation of target lines in the range-time space of a search radar

The average likelihood ratio detector is derived as the optimum detector for detecting a target line with unknown normal parameters in the range-time data space of a search radar, which is corrupted by Gaussian noise. The receiver operation characteristics of this optimum detector is derived to evaluate its performance improvement in comparison with the Hough detector, which uses the return signal of several successive scans to achieve a non-coherent integration improvement and get a better performance than the conventional detector. This comparison, which is done through analytic derivations and also through simulation results, shows that the average likelihood ratio detector has a better performance for different SNR values. This result is justified by showing the disadvantages of the Hough method, which are eliminated by the optimum detector. To have an estimate for the location of the detected target line in the optimum detection method as the Hough method, which detects and localizes the target lines simultaneously, we present the maximum a posteriori probability estimator. The estimation performance of the two methods is then compared and it is shown that the maximum a posteriori probability estimator localizes the detected target lines with a better performance in comparison with the Hough method.     

Limit Cycle in a Four Sectors On-Off Tracking Loop

A simplified model of a bidimensional on-off tracking loop is introduced. By using geometric analysis in the time domain, it is shown that there is a simple mode of limit cycle which is stable in the loop for finite disturbances and for a finite range of change of the loop parameters. The consideration of the unsymmetric general case covers a wide class of cases in which the loop is subjected to constant velocity inputs. A nonfiltering assumption is defined which is needed to establish the connection between the simplified loop and practical systems. The main results are applied to a conventional symmetric loop. The analytic approach developed here is applicable as weil to loops in which the number of sectors is different from four and also to loops containing nonlinearities more complex than simple on-off, like hysteresis.     

空间谐振式MOEMS陀螺致动器研究

研究并设计了一种新型的可应用于微光机电(MOEMS)陀螺的微位移及角度控制致动器。它包括高灵敏度压电陶瓷组件和控制电路,具有对微镜进行微米级位移和角秒级角度精确定位的功能。建立并完成了该致动器的结构模型和有限元仿真,提出了基于MOEMS技术的加工方法。     

低成本U-blox模块的单频GPS/BDS增强PPP定位性能分析

以U-blox单频接收机采集数据,在GPS与GPS/BDS两种解算模式下进行局域增强精密单点定位(PPP)解算,并进行模糊度固定,对其在不同环境下的定位性能进行实验研究和分析。实验结果表明:在静态环境下,GPS/BDS浮点解收敛至cm级需3min左右,较GPS缩短64%,GPS/BDS定位精度RMS在平面与高程方向分别为(3.2cm,2.7cm),较GPS提升(47%,59%);GPS/BDS在30s左右可固定模糊度,固定后定位精度为(0.4cm,1.0cm),较GPS/BDS浮点解提升(88%,63%)。在动态环境下,GPS/BDS浮点解收敛至cm级需4min左右,较GPS提升59%,定位精度为(3.1cm,5.9cm),较GPS提升(34%,43%);GPS/BDS获得固定解需2min左右,固定后定位精度为(0.7cm,1.0cm),较GPS/BDS浮点解提升(77%,83%)。