科氏流量计残余应力影响与处理

为提高科氏流量计的精度,对科氏流量计的精度与科氏传感器的应力进行了研究。从科氏流量计的原理及结构出发,分析了应力与零点稳定度的关系,发现各种不平衡的残余应力给科氏传感器的零点稳定性带来了严重影响。采用热时效、振动时效两种方法对两台标定不合格的传感器分别进行处理,将两台流量计的精度均从1级提高到了0.1级。焊缝的应力检测及传感器标定结果表明,处理后的焊缝残余应力得到降低与均化,科氏传感器的零点稳定度及精度得到显著提高。将该方法推广到大量的科氏传感器上,得到了非常好的应用效果。该方法既提高了科氏流量计的精度,又缩短了生产交货周期,大大提升了生产效率与产品质量。该方法同样适用于提升具有复杂机械结构的传感器的稳定度及精度。     

差分式科氏流量计测量原理和零点不稳定及补偿分析

针对差分式科氏流量计零点不稳定的问题,通过对一次仪表进行建模,分析其测量原理,分析了造成零点不稳定的原因.根据理论分析及实际调试经验,提出了零点补偿措施建议,有利于提升零点稳定性,减少测量误差,提高测量精度.     

利用科氏流量计测量凝析天然气的气液流量

通过研究基于科氏流量计的气液两相流计量技术,提出了科氏流量计的凝析天然气测量模型.该模型较好地表征了科氏流量计的振动频率与阻尼系数的变化规律、振动管与两相流体之间的相对运动关系等.利用E+H公司的微弯科氏流量计开展了一系列试验研究,并结合试验结果对流量计的参数波动特性、安装形式、两相混合物密度测量和质量流量测量等问题进行了深入分析.分析结果为利用科氏流量计实现凝析天然气的高精度计量奠定了基础.     

科氏质量流量计挂壁状态在线监测与校正

科里奥利质量流量计(以下简称科氏质量流量计)振动管内壁的挂壁状态对流量计离线标定、故障诊断以及基于振动的流体粘度测量精度等均存在一定影响.针对这一问题,利用科氏流量计的谐振频率和系统的驱动功率随着内壁的挂壁物质量增大而变化的特性,研究与实现了基于信号特征的科氏质量流量计挂壁状态的在线监测,提高了流体流量、粘度、密度等测...     

科氏质量流量计在尿液流量测量上的应用

简要介绍了科氏质量流量计的测量原理,并对科氏质量流量计在尿液流量测量上选型注意事项以及应用做了较为详细的介绍。     

科氏质量流量计在外输原油自动计量中的应用

科氏质量流量计是一种多功能仪表,在液体计量方面有着广泛的应用前景。本文从其工作原理出发,建立了科氏质量流量计的直接测量参数与间接测量参数之间的关系模型,分析了其间接测量的不确定度,提出了采用科氏质量流量计和低含水分析仪构成原油外输动态油量自动计量系统。计算表明,该自动计量系统具有较高的测量精度,可满足原油外输计量精度的要求,为外输原油自动计量方式的正确、合理选择提供了理论依据。     

基于弯曲振动粘度测量的能耗研究

采用科氏流量计弯曲振动测量粘度其关键在于准确得到粘性力消耗的能量与粘度的关系.采用微元分析方法,系统分析了测量管中轴向无流速时弯曲振动中液体粘性力造成的能量损耗,推导出测量管谐振时消耗功率与粘度的数学模型,并用实验进行了验证.     

科氏流量计故障检测数据清洗方法研究

科里奥利质量流量计(简称科氏流量计)是一种直接式质量流量测量仪表，可以同时测量流体的质量流量、密度等参数。科氏流量计在使用过程中易出现挂壁故障，影响测量精度，因此，需要对挂壁故障进行定期检测。检测所采集的数据质量会影响科氏流量计挂壁故障检测的精度，针对此问题，必须对脏数据进行清洗，进一步提高科氏流量计挂壁故障检测的准确率，提出了一种基于强化学习的数据清洗算法。将数据与后端机器学习模型相结合，使用Q-Learning算法对数据清洗流程进行搜索，寻找能够使后端机器学习模型达到最佳性能的数据清洗策略。最后对科氏流量计挂壁实验数据进行清洗，对算法进行了验证，检测准确率达92%。实验结果表明，该算法在提高数据清洗效率的同时可以有效提高机器学习模型的性能，使挂壁故障检测准确率得到提高。     

抑制气体超声波流量计零点漂移的互易性电路设计

针对气体超声波流量计信号衰减严重、干扰较大的问题,设计了一种适用于气体超声波流量计的互易性收发电路,以消除零点漂移现象提高流量计的测量准确度.换能器配对实验和温度实验表明:互易性测量系统显著改善了流量计的零点漂移问题,并具有良好的测量稳定性.     

基于模拟电路方法的科氏质量流量传感器特性研究

提出了一种基于等效电路研究科氏质量流量传感器结构优化、动态响应的新方法.首先,基于测量管微元的力学平衡关系,构建了科氏质量流量传感器时域振动的数学模型.其次,基于振动模型构建了科氏质量流量传感器等效电路模型,并验证了等效电路的可行性.最后,通过研究等效电路,实现了科氏质量流量传感器在不同参数结构下振动响应的输出信号的获取,并得出科氏质量流量传感器灵敏度和固有频率随测量管长度L变化呈非线性反相关的结论,为科氏质量流量传感器的结构优化提供了新方法、新思路.     

直管科氏质量流量传感器灵敏度分析软件设计

科氏质量流量传感器(CMF)在工业中具有广泛的应用和重要的地位,关于CMF的理论较为成熟,然而目前缺少直接对CMF进行分析的软件。为便利直管型CMF的设计与研发,运用欧拉梁理论,建立了静力学模型和振动力学模型,计算了测量管的挠度曲线和直管型CMF的灵敏度和频率;并考虑温度对材料属性的影响,引入了随温度变化的弹性模量;对直管型CMF进行了压损分析,计算了其压力损失。根据上述理论分析结果,基于Matlab的APP Designer模块,设计了直管型CMF分析的GUI软件,实现了对直管型CMF的灵敏度、频率、压损分析等功能;并使用ANSYS进行了有限元仿真分析,验证了所设计软件的频率和灵敏度分析结果,为后续直管型CMF的设计工作提供了一款便利的、可靠的、可直接对CMF进行分析的GUI软件。     

Output-feedback stabilization of a class of uncertain non-minimum-phase nonlinear systems

The problem of global output-feedback stabilization for a class of nonlinear systems whose zero dynamics are not necessarily stable is addressed in this paper. It is shown that, using a novel observer design tool together with standard backstepping and small-gain techniques, it is possible to design a stabilizing output feedback controller which ensures robustness with respect to dynamic uncertainties. The proposed stabilization method generalizes existing tools in several directions. As an example, the method is applied to the stabilization of the benchmark translational oscillator/rotational actuator (TORA) using only measurements of the rotational position.     

基于FFT和闭环采样控制的科氏质量流量计信号处理系统

针对新型的直管型和微弯管型科氏质量流量计(CMF)基频较高,满量程相位差微小的特点,提出一种以FFT算法为核心,由FPGA硬件逻辑及外围电路实现频率跟踪,通过调整DDS产生可变时钟实现AD采样频率闭环控制的CMF信号处理系统,以满足FFT算法整周期采样的条件,减小由于非整周期截断带来的频谱泄露对计算精度的影响,实现了实...     

一种全数字时基恢复的算法与实现

全数字时基恢复与调整采样时钟相比,具有一定的优势。在参考文献的基础上,结合工作经验,提出了内插滤波器的分级设计理念,以一定的设计复杂度换取较高的内插性能;同时,挑选了较好的二级滤波器设计结构,总结了使用数控振荡器（NCO）求解内插时基的方法,归纳了恢复高性能符号钟所需的提纯方法;最后,给出了仿真结果、占用的硬件资源的统计和系统的处理能力,达到了较好的效果。     

Bandwidth guaranteed multicast scheduling for virtual output queued packet switches

Multicast enables efficient data transmission from one source to multiple destinations, and has been playing an important role in Internet multimedia applications. Although several multicast scheduling schemes for packet switches have been proposed in the literature, they usually aim to achieve only short multicast latency and high throughput without considering bandwidth guarantees. However, fair bandwidth allocation is critical for the quality of service (QoS) of the network, and is necessary to support multicast applications requiring guaranteed performance services, such as online audio and video streaming. This paper addresses the issue of bandwidth guaranteed multicast scheduling on virtual output queued (VOQ) switches. We propose the Credit based Multicast Fair scheduling (CMF) algorithm, which aims at achieving not only short multicast latency but also fair bandwidth allocation. CMF uses a credit based strategy to guarantee the reserved bandwidth of an input port on each output port of the switch. It keeps track of the difference between the reserved bandwidth and actually received bandwidth, and minimizes the difference to ensure fairness. Moreover, in order to fully utilize the multicast capability provided by the switch, CMF lets a multicast packet simultaneously send transmission requests to multiple output ports. In this way, a multicast packet has more chances to be delivered to multiple destination output ports in the same time slot and thus to achieve short multicast latency. Extensive simulations are conducted to evaluate the performance of CMF, and the results demonstrate that CMF achieves the two design goals: fair bandwidth allocation and short multicast latency.     

一种加速度计的标定补偿方法研究

针对微惯性测量组合(MIMU)中的三轴加速度计因为安装误差的缘故,会在恶劣的锥运动环境下出现误差发散问题,本文提出一种基于三轴位置速率转台的静态旋转多位置补偿标定方法.本文通过分析误差角补偿模型来设计相应的标定试验流程,然后利用非线性拟合的数据处理方法,准确计算出标度因数矩阵和加速度计电压.最后,经过标定试验和误差计算,与十二位置标定法对比发现,本文所设计的标定补偿方法能够将误差小一个数量级,能有效提高加速度计输出精度,具有重要的工程实践意义.     

Beyond synchronization: String instability in coupled harmonic oscillator systems

In this paper, we consider the problem of disturbance response and error amplification for a simple system of coupled harmonic oscillators. We first suppose that identical oscillators are connected in a string in which each oscillator attempts to track its predecessor by using the same control law that depends on the relative position information from its immediate predecessor. Such an oscillator string is called a homogeneous oscillator string with predecessor‐following architecture. Motivated by terminology from the problem of vehicle platooning, we say that the synchronized oscillator system is string unstable if the effect of a disturbance to the lead oscillator is amplified as it propagates along the string. With the use of a new Bode‐like integral relation that must be satisfied by the complementary sensitivity function, we provide sufficient conditions for string instability. The sufficient conditions show that any string of oscillators that satisfies certain time domain performance specifications and bandwidth limitations must necessarily be string unstable. We further introduce a concept of time headway for the oscillator system and extend our analysis of string instability to consider the heterogeneous oscillator string and a more general communication range. Copyright © 2014 John Wiley & Sons, Ltd.     

Modeling of a joint-type flexible endoscope based on elastic deformation and internal friction

Flexible endoscopes are widely used in minimally invasive surgical robot systems. Various kinematic models have been developed for describing the deformation of such endoscopes. For joint-type flexible endoscopes, most existing models neglect the effect of internal friction and cannot precisely show the shape.

In this paper, we propose a new nonlinear bending model. The rubber tube and metal net at each joint are approximated as a tube under elastic deformation and are assigned an equivalent bending stiffness. The internal friction force is also taken into account to build the moment balance equation at each joint. Groups of experiments were performed to validate the nonlinear model. The results closely confirm the model’s predictions. The model’s tip position error during the bending and unbending phases are 1.48?±?0.99?mm and 1.68?±?0.91?mm respectively; the bending angle errors are ?5.50?±?2.54° and 1.68?±?3.66°, respectively The model can also take account of the hysteresis effect of the bending, which is quite common for cable-driven flexible robots. Moreover, the model has good computational efficiency, making it suitable for real-time control.     

Load spatial pathway and spine loading: how does lift origin and destination influence low back response?

While heavy lifting has been identified as an important risk factor for low back disorders, little is known about workplace spatial layout – the relative positions of shelves and the impact of this on spine loads. The objective of the current study was to investigate how the relative positions of the load origin and destination impact three-dimensional spine loads. Seven females and seven males lifted an 11.4?kg box from an origin shelf to a destination shelf, each defined by height (elbow, knee and shoulder level) and asymmetry (60° clockwise, sagittally symmetric, 60° counter-clockwise) while their spine loading was assessed by an electromyographic-assisted model. The results indicated that the starting and destination heights and starting task asymmetry all had significant impact on spine compression (with an increase of between 400 and 1900?N when compared to the most neutral position) and lateral shear (with a 100 to 150?N increase) while the destination height impacted the anterior?–?posterior shear forces (with up to 400?N increase). The results of the current study emphasize the importance of proper workplace spatial layout, specifically the importance of specifying starting position of the load relative to the destination. Adjustment of the starting position will impact the three-dimensional spine loads while the destination height and asymmetry influence the shear forces. Furthermore, the influence of the specific pathway (origin relative to destination) indicates there may be a potential preparatory muscle response leading to the loads on the spine. Thus, the pathway of the box plays an important role in the spine responses during lifting, in that longer and non-neutral pathways increase spine loads – indicating the importance of the relative position of the origin and destination shelf.