Ningbo Institute of Measurement and Testing

Ningbo, China

Ningbo Institute of Measurement and Testing

Ningbo, China
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Tang S.-M.,Ningbo Institute of Measurement and Testing | Zhao J.-Y.,Ningbo University | Lu X.-F.,Ningbo Institute of Measurement and Testing
Jiliang Xuebao/Acta Metrologica Sinica | Year: 2015

The machine vision technology applied to the water meter calibration is discribed. Several high speed and high resolution cameras are installed at the top of the checked meter to dynamically access the running water meter image. The meter pointer is accurately positioned using color feature modeling and background Gaussian fitting methods. Machine vision approaches are used to convert the captured images into digital readouts. Encountered problems such as blurred surface and air bubble interfere are overcome. The developed system realizes high efficient automatic water meter verification. ©, 2015, Chinese Society for Measurement. All right reserved.

Zhu S.,Zhejiang University | Liu S.,Zhejiang University | Liu S.,Ningbo Institute of Measurement and Testing | Wang X.,Zhejiang University | Wang H.,Zhejiang University
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering | Year: 2010

In order to optimize the productivity and ensure the running stability of manipulators, a new optimal trajectory planning algorithm is proposed. Position series in joint space are obtained by applying inverse kinematic algorithm to a specified trajectory in task space, and B-splines of seven degree are exploited to interpolate joint position series and generate joint trajectories with continuous velocity, acceleration and jerk, as well as controllable start-stop kinematic parameters. By converting kinematic constraints of manipulators to constraints on control points of B-splines, optimal time nodes are solved by using sequential quadratic programming strategy, then time-optimal and jerk-continuous trajectories which satisfy nonlinear kinematic constraints are planned. Simulating and experimental results show that the proposed trajectory planning algorithm provides ideal trajectories for joint controller, and ensures manipulators to track any specified trajectory in task space stably with the minimum traveling time. © 2010 Journal of Mechanical Engineering.

Tang S.-M.,Ningbo Institute of Measurement and Testing | Hu L.,Zhejiang University | Ma J.,Ningbo Institute of Measurement and Testing
Jiliang Xuebao/Acta Metrologica Sinica | Year: 2013

A no-liquid calibration technique for electromagnetic flowmeter (EMF) is presented. The proposed method utilizes the electromagnetic measuring principle. Several differential equations for the relevant physical quantities and corresponding boundary conditions are established. A set of no-liquid calibration equipment is designed and implemented. By measuring the point-by-point magnetic induction on the boundary surface as well as the structure dimensions of EMF, the sensitivity of EMF are acquired via the numerical solution of the differential equations with measured boundary conditions. The comparison of the no-liquid and practical-flow calibration methods is carried out on two EMFs with diameter of 200 mm. The relative error of the sensitivity data determined by the two methods is less than 0.5%.

Chen Y.J.,China Jiliang University | Chen Y.J.,Ningbo Institute of Measurement and Testing | Shao C.P.,China Jiliang University
Journal of Fluids and Structures | Year: 2013

Small elements of circular, square, triangular and thin-strip cross-sections are used to suppress vortex shedding from a rectangular cylinder of stream-wise to transverse scale ratio L/B=3.0 at Reynolds numbers in the range of Re=V∞B/ν=75-130, where V∞ is the on-coming velocity of the stream, and ν is the kinematic viscosity. The relative transverse dimension of the small element b/B is fixed at 0.2. The results of numerical simulation and visualization experiment show that, vortex shedding from both sides of the cylinder can be suppressed and the fluctuating drag and lift of the cylinder can be greatly reduced, if the element is placed in a certain region referred to as the effective zone. Comparisons at a specific Reynolds number indicate that the square element produces the largest size of the effective zone, whereas the triangular element yields the smallest. Results also show that the effective zone for the square element shrinks with increasing Re and disappears at Re>130. Independent of element cross-section shape and Reynolds number, the center of the effective zone is always at X/B=2.5-3.0 and Y/B≈1.0. The mechanism of the suppression is discussed from the view points of velocity profile stability and stress distribution. © 2013 Elsevier Ltd.

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