Nuclear Magnetic Flowmeter T1 Determination Speed
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Solution Overview
Problem
Current methods for determining the longitudinal relaxation time constant T1 of a medium in nuclear magnetic flowmeters are time-consuming, which impairs further analysis and flow measurement.
Innovation Solution
A method involving nuclear magnetic measurement sequences with inversion, activation, refocusing, and deactivation pulses, along with specific timing and phase cycling, is used to reduce the time required for determining T1, including adjustable waiting intervals and distributed echo signal measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional nuclear magnetic measurement sequences are used to determine T1, then measurement accuracy is maintained, but the determination time becomes excessively long
Solution Approach 1:
The patent divides the measurement process into multiple acquisition processes (at least two) within a single nuclear magnetic measurement sequence. Each acquisition process collects echo signals at different time points, and the T1 value is determined by combining data from all acquisition processes. This segmentation allows parallel data collection that reduces total measurement time while maintaining accuracy through composite analysis.
Solution Approach 2:
The patent employs periodic pulse sequences (inversion pulses, activation pulses, refocusing pulses) with optimized timing intervals. By structuring the measurement as periodic actions with specific repetition intervals and waiting periods, the system efficiently samples the relaxation process at multiple points without requiring sequential completion of traditional long-duration sequences, thereby reducing overall determination time.
2Productivity
If multiple echo signals are measured in different acquisition processes, then T1 determination speed increases, but measurement sequence complexity increases
Solution Approach 1:
The complex measurement task is segmented into multiple manageable acquisition processes, each handling a subset of echo signal measurements. This segmentation makes the overall complex sequence more manageable and implementable by breaking it down into standardized repeating units that can be systematically controlled and processed.
Solution Approach 2:
The patent designs a universal measurement sequence structure that can accommodate multiple acquisition processes with the same pulse sequence template. This multi-functional sequence design allows the system to efficiently handle multiple echo signals using a standardized approach, reducing the need for separate customized sequences and simplifying overall system complexity despite increased measurement capacity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces the time needed to determine the longitudinal relaxation time constant T1, improving the efficiency of nuclear magnetic flowmeter operations and enhancing measurement quality.
Implementation Method 1
A nuclear magnetic flowmeter therefore has a magnetization device for generating a macroscopic magnetic field in a medium present in the measuring tube
Implementation Method 2
An excitation of atomic nuclei with a magnetic moment in a magnetized medium to nuclear magnetic resonances occurs through suitable electromagnetic pulses, which are referred to as activation pulses
Implementation Method 3
The frequency of the precession is called the Larmor frequency ωL and is proportional to the magnitude of the magnetic strength B of the magnetic field. The Larmor frequency is calculated according to ωL = γ B
Implementation Method 4
The rotating transverse macroscopic magnetization can be measured as a free induction decay, abbreviated as FID, or, after refocusing, as an echo signal
Implementation Method 5
The rotating transverse macroscopic magnetization can be measured as a free induction decay, abbreviated as FID, or, after refocusing, as an echo signal
Implementation Method 6
Refocusing takes place using suitable electromagnetic pulses, which are referred to as refocusing pulses. A suitable electromagnetic pulse, which moves the transverse rotating magnetization of the medium back parallel to the macroscopic magnetic field, is called a deactivation pulse
Implementation Method 7
Inversion pulses are also used. These are appropriate electromagnetic pulses that invert the magnetization of the medium parallel to the macroscopic magnetic field, so that the magnetization of the medium is antiparallel to the macroscopic magnetic field
Implementation Method 8
The temporal course of the macroscopic magnetization in a macroscopic magnetic field is called longitudinal relaxation and is characterized by a longitudinal relaxation time constant T1. Longitudinal relaxation is also referred to as spin-lattice relaxation and the longitudinal relaxation time constant as spin-lattice relaxation time constant
Data Source
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AI summary
A method for operating a nuclear magnetic flowmeter (1) is presented and described, wherein the nuclear magnetic flowmeter (1) has a measuring tube (2), a medium (5) is present in the measuring tube (2), and the medium (5) is magnetized in the measuring tube (2). The invention is based on the objective of providing a method in which the time required for determining a longitudinal relaxation time constant T1 of the medium (5) is reduced compared to the prior art. This objective is achieved by performing at least one nuclear magnetic measurement sequence (6, 7) on the medium (5) magnetized in the measuring tube (2), by the at least one nuclear magnetic measurement sequence (6, 7) comprising an inversion pulse (8) and N = {2, 3, 4, ...} acquisition processes (9, 10), and by each of the N acquisition processes (9, 10) starting at a time ts,n with n = {1, ..., N} with respect to the at least one nuclear magnetic measurement sequence (6, 7) begins and has an activation pulse (11), a first waiting interval (12) with a duration Δtd, a first refocusing pulse (13), an echo interval (14) with a duration Δte, a second refocusing pulse (15), a second waiting interval (16) with a duration Δtd and a deactivation pulse (17), that in the echo interval (14) an echo signal se,n is measured and that a longitudinal relaxation time constant T1 of the medium (5) is determined using the echo signals se,1, ..., se,N.