Measurement and control systems for an imaging electromagnetic flow meter

Electromagnetic flow metres based on the principles of Faraday's laws of induction have been used successfully in many industries. The conventional electromagnetic flow metre can measure the mean liquid velocity in axisymmetric single phase flows. However, in order to achieve velocity profile measurements in single phase flows with non-uniform velocity profiles, a novel imaging electromagnetic flow metre (IEF) has been developed which is described in this paper. The novel electromagnetic flow metre which is based on the ‘weight value’ theory to reconstruct velocity profiles is interfaced with a ‘Microrobotics VM1’ microcontroller as a stand-alone unit. The work undertaken in the paper demonstrates that an imaging electromagnetic flow metre for liquid velocity profile measurement is an instrument that is highly suited for control via a microcontroller

The Use of an Orientation Kalman Filter for the Static Postural Sway Analysis

AbstractThe paper presents a quaternion-based extended Kalman filter for postural instability evaluation during stance. It uses low-cost MEMS inertial sensors attached on the lower back of the person at a known height in order to instrumenting the static balancing test. Generally, patients with Parkinson's disease or vestibular-loss are at greater risk for having this problem. The objective of this study was to assess the feasibility of using Kalman filter to characterize the postural steadiness. The Kalman filter is used here as a data fusion algorithm to estimate the orientation of the body based on acceleration and angular rate signals. In order to get the coordinate of the body's centre of mass (CoM), the height of the sensor is projected on the horizontal plane by using the estimated orientation. Many parameters such as the mean velocity of sway, lateral/anterior-posterior range and others are then obtained from the sway path, which help the clinicians to assess the postural instability. The method was tested on 9 healthy individuals (21-31 years). Three different test conditions, namely feet comfortable stance with eyes-open, feet together stance with closed eyes and one-leg stance with eyes-open were evaluated here. The proposed algorithm showed successful estimation of the time-domain parameter for the postural sway analysis

Application of fractional sensor fusion algorithms for inertial mems sensing

The work presents an extension of the conventional Kalman filtering concept for systems of fractional order (FOS). Modifications are introduced using the Grünwald‐Letnikov (GL) definition of the fractional derivative (FD) and corresponding truncation of the history length. Two versions of the fractional Kalman filter (FKF) are shown, where the FD is calculated directly or by augmenting the state vector with the estimate of the FD. The filters are compared to conventional integer order (IO) Position (P‐KF) and Position‐Velocity (PV‐KF) Kalman filters as well as to an adaptive Interacting Multiple‐Model Kalman Filter (IMM‐KF). The performance of the filters is assessed based on a hand and a head motion data set. The feasibility of the given approach is shown. First published online: 14 Oct 201

Joint image and field map estimation for multi-echo hyperpolarized 13C metabolic imaging of the heart

Purpose: Image reconstruction of metabolic images from hyperpolarized C multi-echo data acquisition is sensitive to susceptibility-induced phase offsets, which are particularly challenging in the heart. A model-based framework for joint estimation of metabolite images and field map from echo shift–encoded data is proposed. Using simulations, it is demonstrated that correction of signal spilling due to incorrect decomposition of metabolites and geometrical distortions over a wide range of off-resonance gradients is possible. In vivo feasibility is illustrated using hyperpolarized [1- C]pyruvate in the pig heart. Methods: The model-based reconstruction for multi-echo, multicoil data was implemented as a nonconvex minimization problem jointly optimizing for metabolic images and B . A comprehensive simulation framework for echo shift–encoded hyperpolarized [1- C]pyruvate imaging was developed and applied to assess reconstruction performance and distortion correction of the proposed method. In vivo data were obtained in four pigs using hyperpolarized [1- C]pyruvate on a clinical 3T MR system with a six-channel receiver coil. Dynamic images were acquired during suspended ventilation using cardiac-triggered multi-echo single-shot echo-planar imaging in short-axis orientation. Results: Simulations revealed that off-resonance gradients up to ±0.26 ppm/pixel can be corrected for with reduced signal spilling and geometrical distortions yielding an accuracy of ≥90% in terms of Dice similarity index. In vivo, improved geometrical consistency (10% Dice improvement) compared to image reconstruction without field map correction and with reference to anatomical data was achieved. Conclusion: Joint image and field map estimation allows addressing off-resonance-induced geometrical distortions and metabolite spilling in hyperpolarized C metabolic imaging of the heart. 13 13 13 13 13 0ISSN:0740-3194ISSN:1522-259

Joint image and field map estimation for multi‐echo hyperpolarized 13 C metabolic imaging of the heart

Purpose Image reconstruction of metabolic images from hyperpolarized 13C multi-echo data acquisition is sensitive to susceptibility-induced phase offsets, which are particularly challenging in the heart. A model-based framework for joint estimation of metabolite images and field map from echo shift–encoded data is proposed. Using simulations, it is demonstrated that correction of signal spilling due to incorrect decomposition of metabolites and geometrical distortions over a wide range of off-resonance gradients is possible. In vivo feasibility is illustrated using hyperpolarized [1-13C]pyruvate in the pig heart. Methods The model-based reconstruction for multi-echo, multicoil data was implemented as a nonconvex minimization problem jointly optimizing for metabolic images and B0. A comprehensive simulation framework for echo shift–encoded hyperpolarized [1-13C]pyruvate imaging was developed and applied to assess reconstruction performance and distortion correction of the proposed method. In vivo data were obtained in four pigs using hyperpolarized [1-13C]pyruvate on a clinical 3T MR system with a six-channel receiver coil. Dynamic images were acquired during suspended ventilation using cardiac-triggered multi-echo single-shot echo-planar imaging in short-axis orientation. Results Simulations revealed that off-resonance gradients up to ±0.26 ppm/pixel can be corrected for with reduced signal spilling and geometrical distortions yielding an accuracy of ≥90% in terms of Dice similarity index. In vivo, improved geometrical consistency (10% Dice improvement) compared to image reconstruction without field map correction and with reference to anatomical data was achieved. Conclusion Joint image and field map estimation allows addressing off-resonance-induced geometrical distortions and metabolite spilling in hyperpolarized 13C metabolic imaging of the heart

Considerations for hyperpolarized 13C MR at reduced field: Comparing 1.5T versus 3T

Purpose: In contrast to conventional MR, signal-to-noise ratio (SNR) is not linearly dependent on field strength in hyperpolarized MR, as polarization is generated outside the MR system. Moreover, field inhomogeneity-induced artifacts and other practical limitations associated with field strengths ≥ 3T are alleviated at lower fields. The potential of hyperpolarized 13C spectroscopy and imaging at 1.5T versus 3T is demonstrated in silico, in vitro, and in vivo for applications on clinical MR systems. Theory and Methods: Theoretical noise and SNR behavior at different field strengths are investigated based on simulations. A thorough field comparison between 1.5T and 3T is performed using thermal and hyperpolarized 13C spectroscopy and imaging. Cardiac in vivo data is obtained in pigs using hyperpolarized [1-13C] pyruvate spectroscopy and imaging at 1.5T and 3T. Results: Based on theoretical considerations and simulations, the SNR of hyperpolarized MR at identical acquisition bandwidths is independent of the field strength for typical coil setups, while adaptively changing the acquisition bandwidth proportional to the static magnetic field allows for net SNR gains of up to 40% at 1.5T compared to 3T. In vitro 13 C data verified these considerations with less than 7% deviation. In vivo feasibility of hyperpolarized [1-13 C] pyruvate dynamic metabolic spectroscopy and imaging at 1.5T is demonstrated in the pig heart with comparable SNR between 1.5T and 3T while B 0 artifacts are noticeably reduced at 1.5T. Conclusion: Hyperpolarized 13 C MR at lower field strengths is favorable in terms of SNR and off-resonance effects, which makes 1.5T a promising alternative to 3T, especially for clinical cardiac metabolic imaging.ISSN:0740-3194ISSN:1522-259

Modelling the constitutive behaviour of martensite and austenite in shape memory alloys using closed-form analytical continuous equations

Shape Memory Alloy (SMA) actuators capable of precise position control are faced with numerous challenges attributed mostly to the extreme non-linearities of such alloys. The development of control strategies for such actuators is alleviated by the use models incorporating these non-linearities. Such models should, however, among other characteristics, be real-time capable in order to bring reasonable benefits. This work presents a novel constitutive phenomenological model for martensite and austenite. The model is based entirely on continuous differentiable analytical equations and these closed-form equations are capable of depicting the smooth curvatures observed in the SMA stress-strain characteristic with few and easy to identify physical parameters. They can describe shape changes in both SMA phases (martensite or austenite) when subjected to monotonic as well as cyclic loading, including minor loop behaviour. The model is validated by stress-strain experiments and the results show outstanding correlation with experimental data. Since the model is based on simple closed-form equations, it is extremely computational efficient and can build the foundation for the development of real-time capable SMA models for control algorithms

A Foot-Mounted Pedestrian Localization System with Map Motion Constraints

The work proposes a navigation system for pedestrian indoor localization. The system employs a cascaded architecture, where the information from the foot-mounted inertial unit is combined with the map-induced motion constraints. As the first stage, an Extended Kalman filter with a zerovelocity update (ZUPT) is used to get incremental heading and position information from the inertial sensor measurements. This is followed by motion filtering based on map constraints implemented in a form of SIR particle filter. Compared to a pure inertial approach without the map filtering, the proposed method shows a significant performance improvement for typical indoor scenarios and is shown to be superior to a non-gyroscopic pedometer approach with map constraints