KRF系列射频导纳物位计的开发与应用

鉴于传统电容式物位计存在的缺陷,开发KRF系列射频导纳物位计。本文阐述KRF系列射频导纳物位计的基本原理,给出测试系统的主要技术指标,并对其性能进行了测试。开发的KRF物位计有效地解决了传统物位测量过程中存在的挂料问题,能够精确地进行物位测量。     

西门子SITRANS Probe LU物位计

西门子SITRANS Probe LU高精确度的一体化超声波物位计，现在可提供Profibus—PA通信。Profibus作为一种标准的现场总线通信方式，被越来越多的客户和供应商接受和采用。SITRANS Probe LU同时也可提供HART通信方式。用户可以通过手操器和SIMATIC PDM软件对仪表进行调试。西门子的雷达、超声波物位计和射频导纳点式物位计均可选配Profibus—PA通信。     

核辐射物位计的应用案例及标定方法

核辐射物位计是一种放射性同位素仪表，属于非接触式测量仪表，特别适用于密闭容器中高温、高压、高粘度、强腐蚀、剧毒物料料位的测量。它与DCS配套使用，还可以实现料位异常报警、自动控制及设备安全联锁，降低人员劳动强度。本文主要介绍了核辐射物位计在氧化铝生产装置上的应用情况及核辐射物位计物位标定的经验方法。     

新型物位计在电厂固体物位测量上的应用

本文针对燃煤电厂固体物位测量存在的问题,对近几年逐渐得到广泛应用的超声波式、雷达式、射频导纳式等新型物位计,从测量原理、特点和应用范围等方面进行了分析,并对华能德州电厂的应用情况进行了介绍。     

双雷达测量法在干式煤气柜柜位测量上的应用

雷达物位计是一种利用微波信号的传输来测量物位的非接触式物位计。该文通过双雷达物位计在煤气柜柜位测量上的应用,针对应用过程中存在的问题,通过优化煤气柜雷达物位计安装以及对物位计杂波、虚假波进行过滤、消除干扰等措施,解决了2台雷达物位计对同一测量对象同时工作时雷达波的相互交叉干扰问题,提高了雷达物位计测量准确性。     

AP1000中雷达液位计的问题分析

雷达液位计是一种利用电磁波测量物位的仪表,按照测量原理,现在广泛使用的雷达物位计有以下3种类型:脉冲雷达物位计,调频连续波雷达物位计和导波雷达物位计。根据现场不同工况,液位计的错误选型影响仪表测量的可靠性。介绍AP1000项目现场采用脉冲雷达物位计产生的问题,进行问题分析,提出解决方案。     

浅析雷达物位计在测量中的应用

雷达物位计应用智能电子部件计算出通过天线发射并接收微波经历的时间,转换成物位计到反射介质表面的距离。它采用先进的雷达技术,即使在氧化铝生产工况复杂,高温、蒸汽大、介质腐蚀性强、泡沫、容易结疤等恶劣条件下,都能准确测出液面高度。通过对雷达物位计测量原理的介绍,并对雷达物位计的特点、安装注意事项、使用方面进行探讨,规避虚假回波,从而更好地应用雷达物位计。     

改进雷达安装结构在膏体智能充填的应用

根据膏体充填智能控制的工艺要求，采用雷达物位计控制充填的自动停止，主要研究雷达物位计的安装结构和膏体充填物位增长方式，建立待充填量测算数据模型，根据物位距离在线动态估算剩余充填方量，从而保证准确充填，防止堵管。     

基于EPA通信卡的调频连续波雷达物位计设计

针对现代工业对高精度物位测量技术网络化的要求,设计了以EPA实时通信控制系统为基础,以DSP为核心的高精度调频连续波雷达物位计.将物位计接入EPA网络, 实现由以太网的实时运动控制, 采用模块化的设计思想, 为所开发的调频连续波雷达物位计设计了高速智能 EPA通信接口.该模块核心为AT91R40008 ARM7处理器, 由AX88796网卡芯片实现TCP/IP协议的解析.还介绍了物位计和EPA接口卡外围电路的实现方法,及物位计开发中要注意的一些问题.测试表明采用EPA接口卡的物位计具有低功耗和高精度等特点.     

脉冲时域反射物位计在电厂中的应用

以英国FLT公司的FLT9100为例说明脉冲时域反射物位计在电厂中的典型应用,并对脉冲时域反射物位计在各种工况下应用的优缺点进行了阐述。     

一种有效的地图创建方法和机器人的路径规划

介绍了一种新的移动机器人基于多边形的地图创建方法(三角形法)和在此基础上的基于遗传算法的移动机器人路径规划算法,并进行了仿真试验。三角形法是在可视图法的基础上,通过删除冗余的地图信息而得到的一种更加精简更能清楚表现障碍物之间关系的地图创建方法。在此基础上实现遗传算法路径规划,通过快速的迭代便能够找到最优的路径。     

圆锥型压电换能器的动态设计与实验研究

对一种圆锥型夹心式压电换能器进行了动态设计与实验分析。利用有限元分析方法对换能器进行了动态设计,给出了该类压电换能器有限元建模方法,分析了换能器主要结构尺寸对振动模态、固有频率的影响。依据有限元分析结果,提出了一种基于数值分析的换能器优化设计方法,简化了设计过程。在数值分析的基础上,设计、研制了圆锥型夹心式压电换能器,并对压电换能器进行了性能测试。并将实验测试数据和有限元分析结果进行了对比,测试结果验证了数值分析与设计方法的合理性。     

An improved three-point method based on a difference algorithm

The reason for the rounding error in a measurement system under the condition of a limited sampling period is analysed, and a three-point method based on the difference algorithm (D3P method) is proposed. The effect of the rounding error is reduced by differential approximation of the roundness error and reconstruction of the transfer function. The generalized three-point method (G3P method), the three-point method based on the first-order difference algorithm (I-D3P method) and the three-point method based on the second-order difference algorithm (II-D3P method) are compared and analysed by simulation. The results show that the accuracy of the D3P method is greatly improved compared with that of the G3P method under the restricted sampling period and that the D3P method retains high precision in the case of failed error separation of the G3P method. An experimental system was constructed to realize error separation, and the experimental results show that the D3P method has higher accuracy than the G3P method over a small sampling period.     

An adaptive stochastic resonance method based on grey wolf optimizer algorithm and its application to machinery fault diagnosis

Stochastic resonance (SR) is widely used as an enhanced signal detection method in machinery fault diagnosis. However, the system parameters have significant effects on the output results, which makes it difficult for SR method to achieve satisfactory analysis results. To solve this problem and improve the performance of SR method, this paper proposes an adaptive SR method based on grey wolf optimizer (GWO) algorithm for machinery fault diagnosis. Firstly, the SR system parameters are optimized by the GWO algorithm using a redefined signal-to-noise ratio (SNR) as optimization objective function. Then, the optimal SR output matching the input signal can be adaptively obtained using the optimized parameters. The proposed method is validated on a simulated signal detection and a rolling element bearing test bench, and then applied to the gear fault diagnosis of electric locomotive. Compared with the conventional fixed-parameter SR method, the adaptive SR method based on genetic algorithm (GA-SR) as well as the well-known fast kurtogram method, the proposed method can achieve a greater accuracy. The results indicated that the proposed method has great practical values in engineering.     

Type Synthesis of Lower Mobility Parallel Mechanisms: A Review

Type synthesis of mechanisms aims to systematically determine all possible structures for a specific mobility requirement. Numerous methods based on di erent theories were proposed for type synthesis of lower mobility parallel mechanisms in past decades. However, there does not exist a comprehensive review on these approaches. Therefore, the goal of this paper is to give such a review, classifying the approaches proposed in the literature into three groups, namely, motion-based methods, constraint-based methods, and other methods. The motion-based methods include the Lie group based method, the GF set method, the linear transformation method, the POC set method,and the finite screw method. The constraint-based methods involve the screw theory-based method, the virtual chain method, the method based on Grassmann line geometry and line graphs, and the motion constraint generator method. Other methods contain the enumeration approach based on the general CGK mobility formula and the graph theory method. Upon thoroughly analyzing the characteristics and/or limitations of each method, this review provides a well reference to help researchers find an e ective synthesis method for innovative design and further scientific investigations for mechanisms.     

Rapid optimization of tension distribution for cable-driven parallel manipulators with redundant cables

The solution of tension distributions is infinite for cable-driven parallel manipulators(CDPMs) with redundant cables. A rapid optimization method for determining the optimal tension distribution is presented. The new optimization method is primarily based on the geometry properties of a polyhedron and convex analysis. The computational efficiency of the optimization method is improved by the designed projection algorithm, and a fast algorithm is proposed to determine which two of the lines are intersected at the optimal point. Moreover, a method for avoiding the operating point on the lower tension limit is developed. Simulation experiments are implemented on a six degree-of-freedom(6-DOF) CDPM with eight cables, and the results indicate that the new method is one order of magnitude faster than the standard simplex method.The optimal distribution of tension distribution is thus rapidly established on real-time by the proposed method.     

Calculation method of radial stress and deformation on conic threaded connections with interference fit

This paper presents a calculation method for radial stress distribution and deformation on conic threaded connections with interference fit. Based on elastic mechanics, a new calculation model is established using the thick-walled-cylindrical theory. A sample calculation for API 88.9 mm conic threaded connection indicates that the method proposed in this paper is reasonable, and the finite element analysis (FEA) method is used to validate the proposed method. The results obtained by the proposed method and FEA method are identical. The model offers a new way of calculating the radial stress and deformation on conic thread connections with interference fit.     

频率依赖性黏弹性复合板动力学特性计算方法

将涂覆黏弹性阻尼的压气机叶片简化为考虑频率依赖性的黏弹性复合板,基于经典模态应变能法推导了一种修正的模态应变能法,用于黏弹性复合板的损耗因子计算.设计了一种基于修正模态应变能法的迭代求解方法,通过算例分别使用该计算方法与复特征值迭代法计算考虑频率依赖性的黏弹性复合板动力学特性.结果表明:基于修正模态应变能法的迭代求解方...     

机构综合的混沌相乘求解方法研究

混沌是现代科学的主要成就之一,扩展混沌的应用对现代科学的发展有重要意义。机构综合问题可以转化为非线性方程组求解,牛顿迭代法是重要的一维及多维迭代技术,其迭代本身对初始点非常敏感。文中研究了混沌相乘方法,并对其进行了仿真,首次提出了基于混沌相乘方法的非线性方程组求解新方法,并对机构综合进行了研究,给出了计算实例。该方法简单、实用,为实际机构的设计提供了多种选择方案,是用于机构学设计的全新方法。     

求点到空间参数曲线最小距离的几种算法

建立了点到空间参数曲线最小距离的数学模型,提出了计算点到空间参数曲线最小距离的三种算法,即基于几何特征的快速迭代法、基于最优化方法的黄金分割法与二次迭代法的组合法以及格点法,分析比较了这三种算法的特点和适用范围,编制了相应的计算机程序,实现了求点到复杂曲线的最小距离,并对三种算法的计算精度和运行时间作了比较。大量算例验证了算法的有效性,其计算精确度高,非常适用于曲面、曲线的匹配计算和三坐标测量机的点相关数据处理,在工程上具有一定的实用价值。