A parametric interpolator with confined chord errors, acceleration and deceleration for NC machining

Parametric interpolation has many advantages over linear interpolation in machining curves. Real time parametric interpolation research so far has addressed achieving a uniform feed rate, confined chord errors and jerk limited trajectory planning. However, simultaneous consideration of confined chord errors that respect the acceleration and deceleration capabilities of the machine has not been attempted. In this paper, the offline detection of feed rate sensitive corners is proposed. The velocity profile in these zones is planned so that chord errors are satisfied while simultaneously accommodating the machine's acceleration and deceleration limits. Outside the zone of the feed rate sensitive corners, the feed rate is planned using the Taylor approximation. Simulation results indicate that the offline detection of feed rate sensitive corners improves parametric interpolation. For real time interpolation, the parametric curve information can be augmented with the detected feed rate sensitive corners that are stored in 2×2 matrices.     

Study on the Intelligent System of Gear Pitch Deviation Measurement and Analysis

The intelligent controlling and data process of pitch error measurement is proposed. The whole system takes C++ as the development tool and takes advantages of object-oriented and visualization, having the advantages of easy operation and humanistic interface. In the meanwhile, the system can be complemented and improved according to the demand of user, having certain independence. The research of the system provides an efficient and reliable way to measure and analyze the gear pitch, which can be referenced in the future research.     

Method of Reducing Error in Calculations of Active Power from Signal Samples

The paper presents the results of investigations into several methods of calculating the active power value from current and voltage signal samples. The accuracy attainable for nonsinusoidal signals whose frequency differs from the nominal one was determined. A new active power calculation method ensuring accurate results for sampling over two signal periods is proposed. The method uses a very simple computing algorithm.     

水上地震折射互换法误差分析

在理论上，用源检互换的方法进行折射地震勘探是没有误差的，在某些特殊条件下无法铺设检波器而又必须进行折射地震勘探时它也是唯一的选择，然而，在实际工作中，由于各种因素的影响，其误差是不可忽略的。为此，本文从地震折射运动学的角度对水上地震折射互换法因过河钢丝绳的重量、水的流速和流向、炮点深度等客观因素造成的解释误差进行了分析，揭示了水上地震折射互换法应注意的问题。这对水上地震折射互换法的资料解释进行误差校正提供了理论基础。     

Estimation of errors of hydrogen standard time scale preservation taking account of systematic frequency changes

Metrological characteristics of active hydrogen frequency standards are investigated on the basis of internal and external comparisons. The stability of random changes and drift of hydrogen frequency standards and also the potential capabilities of time scale preservation with effective consideration of systematic changes in their frequency are demonstrated. __________ Translated from Izmeritel’naya Tekhnika, No. 3. pp. 42–45, March, 2007.     

海底管道的沉降量计算

根据极限平衡和极限分析方法,建立了软黏土地基土体上海底管道的极限承载力计算公式。当地基处于极限状态时,基础作用于地基的全部荷载应该等于该地基土体的承载能力,根据这一关系式可以推导出海底管道沉降量的计算公式。通过对试验结果的分析,证实所采用的计算方法是可行的。     

在以纯碱为原料的非强酸性水溶液体系中采用酸碱滴定分析的误差来源及分析方法的改进

以三聚磷酸钠生产过程为例,论述了在以纯碱为原料的非强酸性水溶液体系中,由于反应不完全导致反应物中存在少量的碳酸盐,这部分碳酸盐干扰了用酸碱滴定法测量的中和度,并据此提出中和度分析改进方法.由此可以推广到其它以纯碱为原料的非强酸性水溶液体系中.     

影响GPS水准高程的因素及高程拟合方法的探讨

在简单介绍高程系统的基础上，对影响GPS高程精度的几何水准联测误差、卫星分布不对称、星历误差、多路径误差等因素逐一进行了分析，并提出了相应的改进措施。同时，还对高程拟合使用的稳健估计方法进行了探讨。     

Measuring the errors of form of industrial surfaces: prediction and optimization

To acquire maximum information on the geometrical errors of industrially made surfaces at a minimum cost, a method for estimating conditional probabilities of a random signal (Bayesian prediction) is applied to three-dimensional metrology. First, a surface is interpolated between data acquired on a coordinate measuring machine (CMM). Then, for a given probability, limit surfaces are computed that bind a region of space containing the known data and the most probable interpolation of the missing data of the surface. These bounds can be treated as the surface; their points can be considered as if they were actual CMM data when fitting a tolerance zone or a datum feature to the data. For Bayesian prediction, the basic hypotheses on the signal are stationarity, ergodicity, and gaussian density. Deviations from these hypotheses and their consequences on the prediction are taken into account and corrections are proposed.     

平均声压级近似计算误差分析

本文用凸集理论分析了平均声压级近似计算的误差,导出了最大误差计算公式,指出了测量数据在何种状态下误差达到最大值。