scholarly journals On the Temporal Fidelity of Nonlinear Inverse Reconstructions for Real- Time MRI – The Motion Challenge

2014 ◽  
Vol 8 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Jens Frahm ◽  
Sebastian Schätz ◽  
Markus Untenberger ◽  
Shuo Zhang ◽  
Dirk Voit ◽  
...  
Keyword(s):  
Real Time ◽  
Median Filter ◽  
Joint Estimation ◽  
Acquisition Time ◽  
Reconstruction Method ◽  
Temporal Filtering ◽  
Inverse Reconstruction ◽  
Object Movement ◽  
T1 Contrast ◽  
Motion Assessment

Purpose: To evaluate the temporal accuracy of a self-consistent nonlinear inverse reconstruction method (NLINV) for real-time MRI using highly undersampled radial gradient-echo sequences and to present an open source framework for the motion assessment of real-time MRI methods. Methods: Serial image reconstructions by NLINV combine a joint estimation of individual frames and corresponding coil sensitivities with temporal regularization to a preceding frame. The temporal fidelity of the method was determined with a phantom consisting of water-filled tubes rotating at defined angular velocity. The conditions tested correspond to real-time cardiac MRI using SSFP contrast at 1.5 T (40 ms resolution) and T1 contrast at 3.0 T (33 ms and 18 ms resolution). In addition, the performance of a post-processing temporal median filter was evaluated. Results: NLINV reconstructions without temporal filtering yield accurate estimations as long as the speed of a small moving object corresponds to a spatial displacement during the acquisition of a single frame which is smaller than the object itself. Faster movements may lead to geometric distortions. For small objects moving at high velocity, a median filter may severely compromise the spatiotemporal accuracy. Conclusion: NLINV reconstructions offer excellent temporal fidelity as long as the image acquisition time is short enough to adequately sample (“freeze”) the object movement. Temporal filtering should be applied with caution. The motion framework emerges as a valuable tool for the evaluation of real-time MRI methods.

JOINT ESTIMATION OF THE TRANSMISSIBILITY AND SEVERITY OF EBOLA VIRUS DISEASE IN REAL TIME

2017 ◽  
Vol 25 (04) ◽  
pp. 587-603 ◽  
Author(s):  
YUSUKE ASAI ◽  
HIROSHI NISHIURA
Keyword(s):  
Real Time ◽  
Ebola Virus ◽  
Virus Disease ◽  
Critical Role ◽  
Estimation Method ◽  
Case Fatality ◽  
Ascertainment Bias ◽  
Joint Estimation ◽  
Ebola Virus Disease ◽  
Strong Impact

The effective reproduction number [Formula: see text], the average number of secondary cases that are generated by a single primary case at calendar time [Formula: see text], plays a critical role in interpreting the temporal transmission dynamics of an infectious disease epidemic, while the case fatality risk (CFR) is an indispensable measure of the severity of disease. In many instances, [Formula: see text] is estimated using the reported number of cases (i.e., the incidence data), but such report often does not arrive on time, and moreover, the rate of diagnosis could change as a function of time, especially if we handle diseases that involve substantial number of asymptomatic and mild infections and large outbreaks that go beyond the local capacity of reporting. In addition, CFR is well known to be prone to ascertainment bias, often erroneously overestimated. In this paper, we propose a joint estimation method of [Formula: see text] and CFR of Ebola virus disease (EVD), analyzing the early epidemic data of EVD from March to October 2014 and addressing the ascertainment bias in real time. To assess the reliability of the proposed method, coverage probabilities were computed. When ascertainment effort plays a role in interpreting the epidemiological dynamics, it is useful to analyze not only reported (confirmed or suspected) cases, but also the temporal distribution of deceased individuals to avoid any strong impact of time dependent changes in diagnosis and reporting.

scholarly journals Digital Data Processing Methods for Estimating Tractive Force of Tractors

2021 ◽  
Vol 31 (1) ◽  
pp. 127-142
Author(s):  
Vyacheslav F. Fedorenko ◽  
Vitaly E. Tarkivskiy ◽  
Nikolay P. Mishurov ◽  
Nikolay V. Trubitsyn
Keyword(s):  
Real Time ◽  
Strain Gauge ◽  
Impulse Noise ◽  
Median Filter ◽  
Digital Processing ◽  
Operating Conditions ◽  
Measuring Instruments ◽  
Important Indicator ◽  
Tractive Effort ◽  
Useful Signal

Introduction. When carrying out an energy assessment of agricultural machines and traction tests of tractors, the most important indicator is the value of the tractive effort. The existing methods for determining the tractive effort of tractors imply the use of specialized measuring instruments, such as strain gauges and devices for processing and displaying information. The accuracy of determining the tractive effort is significantly influenced by the physical and mechanical properties of soil. To process the useful signal during the measurement of tractive effort, the data stream of the strain gauge sensor must be subjected to additional digital filtering taking into account the operating conditions of the agricultural unit. Materials and Methods. The functions of changing the tractive effort obtained on the K-744R2 tractor in various gears have been analyzed. An algorithm for digital processing of the signal of a strain gauge force meter based on a median filter has been developed that makes it possible to increase the measurement accuracy. The advantage of the proposed method is the ability to cut off sharp short-term impulse noise and sharp fluctuations in the amplitude of the measured value. Results. A method for determining the amount of tractive effort using median signal processing has been proposed. A device for determining the tractive effort during testing of agricultural tractors and units has been developed. The choice of the main components of the device for determining the magnitude of the tractive effort has been substantiated. As a result of the research, a device for measuring and digital processing of the signal of a force meter based on a microcontroller and specialized software for processing initial data in real time was designed and manufactured. Discussion and Conclusion. The developed method makes it possible to exclude the negative effect of impulse noise arising in the process of measuring the tractive effort of the tractor. The proposed device for measuring the tractive effort of tractors is compatible at the level of the exchange protocol with existing devices, has a high speed of operation in real time, multi-channel operation.

scholarly journals Nonlinear Pulse-Time Conversion in Radioisotope Devices: Analysis and Application Possibilities

2021 ◽  
Vol 12 (2) ◽  
pp. 133-138
Author(s):  
A. M. Vodovozov
Keyword(s):  
Real Time ◽  
Radiation Detector ◽  
Flaw Detection ◽  
Transformation Function ◽  
Computing Device ◽  
Measuring Devices ◽  
Object Movement ◽  
Set Of Points ◽  
Pulse Flux ◽  
Time Pulse

The paper considers the operation of radioisotope measuring devices under dynamic conditions, when the Poisson pulse flux at the output of the radiation detector becomes unsteady and the nonlinearity of the calibration curve of the device, the stochasticity of the radiation signal and the inertia of the meter significantly complicate the task of estimating the measured physical parameter. of the device and analysis of the possibility of its application for linearization of the characteristics of the device, increasing the speed of the devices and solving the measuring problem in real time.The process of nonlinear transformation of the radiation signal in the system is analyzed on the basis of the assumption about the exponential distribution of the intervals between the pulses of the information flow at the output of the radiation detector. A generalized algorithm for the synthesis of a given transformation function of a time-pulse computing device of a radioisotope device has been developed according to its mathematical description. To describe the transformation function given by a set of points, it is proposed to use its approximation by a power series.The proposed calculation formulas are verified by modeling in the Scilab program on a specific example of linearization of the curve of a radioisotope altimeter with a given tabular calibration characteristic. The results obtained confirm the expediency of using time-pulse computing devices for linearizing the conversion curve of radioisotope devices in real time.Carrying out calculations according to the proposed algorithms by means of modern microelectronics opens up new possibilities for expanding the field of application of radioisotope devices in dynamic problems of industrial flaw detection, measuring the parameters of object movement, thickness of rolled products and coatings, in devices for continuous monitoring of liquid media.

A Robust and Real-Time Full 3D Reconstruction Method Based on Multiple Kinect

2018 ◽  
pp. 1420-1428
Author(s):  
Xiongfeng Peng ◽  
Liaoyuan Zeng ◽  
Wenyi Wang ◽  
Zhili Liu ◽  
Yifeng Yang ◽  
...  
Keyword(s):  
3D Reconstruction ◽  
Real Time ◽  
Reconstruction Method

scholarly journals Rapid Reconstruction of Simulated and Experimental Temperature Fields Based on Proper Orthogonal Decomposition

2020 ◽  
Vol 10 (11) ◽  
pp. 3729
Author(s):  
Minxin Chen ◽  
Shi Liu ◽  
Shanxun Sun ◽  
Zhaoyu Liu ◽  
Yu Zhao
Keyword(s):  
Temperature Field ◽  
Numerical Methods ◽  
Proper Orthogonal Decomposition ◽  
Real Time ◽  
Orthogonal Decomposition ◽  
Reconstruction Method ◽  
Gas Combustion ◽  
Field Reconstruction ◽  
Proper Orthogonal ◽  
Temperature Field Reconstruction

Temperature information has a certain significance in thermal energy systems, especially in gas combustion systems. Generally, measurements and numerical calculations are used to acquire temperature information, but both of these approaches have their limitations. Constrained by cost and conditions, measurement methods are difficult to use to reconstruct the temperature field. Numerical methods are able to estimate the temperature field; however, the calculation process in numerical methods is very complex, so these methods cannot be used in real time. For the purpose of solving these problems, a two-dimensional temperature field reconstruction method based on the proper orthogonal decomposition (POD) algorithm is proposed in this study. In the proposed method, the temperature field reconstruction task is transformed into an optimization problem. Theoretical analysis and simulations show that the proposed method is feasible. Gas combustion experiments were also performed to validate this method. Results indicate that the proposed method can yield a reliable reconstruction solution and can be applied to real-time applications.

scholarly journals A Real-Time 3D Measurement System for the Blast Furnace Burden Surface Using High-Temperature Industrial Endoscope

Sensors ◽  
2020 ◽  
Vol 20 (3) ◽  
pp. 869 ◽  
Author(s):  
Tianxiang Xu ◽  
Zhipeng Chen ◽  
Zhaohui Jiang ◽  
Jiancai Huang ◽  
Weihua Gui
Keyword(s):  
Blast Furnace ◽  
High Temperature ◽  
Real Time ◽  
Measurement System ◽  
Reconstruction Method ◽  
3D Measurement ◽  
3D Shape ◽  
Camera Array ◽  
3D Measurement System ◽  
High Dust

Capturing the three-dimensional (3D) shape of the burden surface of a blast furnace (BF) in real-time with high accuracy is crucial for improving gas flow distribution, optimizing coke operation, and stabilizing BF operation. However, it is difficult to perform 3D shape measurement of the burden surface in real-time during the ironmaking process because of the high-temperature, high-dust, and lightless enclosed environment inside the BF. To solve this problem, a real-time 3D measurement system is developed in this study by combining an industrial endoscope with a virtual multi-head camera array 3D reconstruction method. First, images of the original burden surface are captured using a purpose-built industrial endoscope. Second, a novel micro-pixel luminance polarization method is proposed and applied to compensate for the heavy noise in the backlit images due to high dust levels and poor light in the enclosed environment. Third, to extract depth information, a multifeature-based depth key frame classifier is designed to filter out images with high levels of clarity and displacement. Finally, a 3D shape burden surface reconstruction method based on a virtual multi-head camera array is proposed for capturing the real-time 3D shape of the burden surface in an operational BF. The results of an industrial experiment illustrate that the proposed method can measure the 3D shape of the entire burden surface and provide reliable burden surface shape information for BF control.

Research on Boom-Type Roadheader Vibration Testing Based on the LabVIEW

2011 ◽  
Vol 418-420 ◽  
pp. 1988-1991
Author(s):  
Li Juan Zhao ◽  
Xiu Mei Lv ◽  
Wei Tong
Keyword(s):  
Real Time ◽  
Detection System ◽  
Structural Characteristics ◽  
Test System ◽  
Vibration Characteristics ◽  
Acquisition Time ◽  
Vibration Source ◽  
Time Data ◽  
Vibration Signals ◽  
Time Frequency

This develops the roadheader vibration characteristics test system according to the structural characteristics and working principle of the cantilevered roadheader. Using the piezoelectric acceleration sensor detects vibration signal, and passing by signal processing and A/D conversion， vibration signals are sent to the PC with wireless transmission mode, vibration signals detected by the LabVIEW is realized real-time data acquisition, time-frequency analysis and digital processing. Based on this system testing results can effectively master roadheader operation state, identify the vibration characteristics, look for vibration source and put forward reasonable damping vibration measure, which provide the basis for roadheader in the best running condition. The development of roadheader vibration detection system uses the method that combines theory and simulation experiment , which realizes the real-time detection of roadheader vibration behavior, rational signal analysis of roadheader vibration and accurate processing of data results, it provides an important method to ensure the reliability of roadheader.

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