Electromagnetic Measurement System Research Articles

Ramp lesions of the medial meniscus are associated with greater preoperative anterior knee laxity in anterior cruciate ligament injury.

To assess the incidence of ramp lesions in anterior cruciate ligament (ACL) injuries and to compare preoperative knee laxity between the patients with and without ramp lesions by using an electromagnetic measurement system (EMS). Two hundred six patients who underwent primary ACL reconstruction with preoperative EMS measurements were retrospectively enrolled in the present study. The diagnoses of the ramp lesions were made by arthroscopic inspections. The patients with ramp lesions and no other meniscal lesions were allocated to 'ramp group', and the patients without any meniscal lesions were allocated to 'control group'. Before ACL reconstruction under general anaesthesia, the side-to-side difference (SSD) in anterior tibial translation (ATT) during Lachman test (mm) and tibial acceleration (m/s2) of posterior tibial reduction during the pivot-shift test was measured using the EMS. The SSD in tibial internal/external rotation angle (°) at 30, 60 and 90 were further measured using the EMS. The SSD in ATT using KT-2000 was also measured. Knee laxity measurements were compared between two groups using unpaired Student's t test. Ramp lesions were observed in 30 patients (14.7%). Subsequently, 17 patients were allocated to 'ramp group' and 77 patients to 'control group', and there were no statistical differences with regard to background demographics. ATT-SSD during Lachman test was significantly greater in 'ramp group' (9.1 [95% confidence interval, CI: 5.7-12.5] mm vs. 6.2 [95% CI: 5.1-7.3] mm, p = 0.037). However, SSD in ATT with KT-2000, tibial acceleration during pivot-shift test, and SSD in tibial rotational angles were not significantly different between the two groups. Presence of ramp lesion was associated with increased anterior knee laxity during Lachman test, suggesting ramp lesions may need to be addressed at the time of ACL reconstruction. IV.

Research on Construction of Test Environment for Assessment of RF-Induced Heating Effects of Implants

In magnetic resonance examination, the interaction between implants and the radio frequency (RF) fields induces heating in human tissue and may cause tissue damage. To assess the RF-induced heating of implants, three steps should be executed, including electromagnetic model construction, electromagnetic model validation, and virtual human body simulations. The crucial step of assessing RF-induced heating involves the construction of a test environment for electromagnetic model validation. In this study, a hardware environment, comprised of a RF generation system, electromagnetic field measurement system, and a robotic arm positioning system, was established. Furthermore, an automated control software environment was developed using a Python-based software development platform to enable the creation of a high-precision automated integrated test environment. The results indicate that the electric field generated in this test environment aligns well with the simulated electric field, making it suitable for assessing the RF-induced heating effects of implants.

Injuries to both anterolateral ligament and Kaplan fiber of the iliotibial band do not increase preoperative pivot-shift phenomenon in ACL injury

BackgroundTo assess the incidence of anterolateral ligament (ALL) and Kaplan fiber of the iliotibial band (KF) injuries in patients with acute anterior cruciate ligament (ACL) injury on magnetic resonance imaging (MRI), and to investigate the association between these injuries and the magnitude of preoperative pivot-shift test. MethodOne-hundred and five patients with primary ACL injury were retrospectively reviewed. ALL injury and KF injury were assessed by preoperative MRI, and subjects were allocated into four groups: Group A, neither injury; Group B, only ALL injury; Group C, only KF injury; Group D, simultaneous ALL and KF injuries. Before ACL reconstruction, tibial acceleration during the pivot-shift test was measured by an electromagnetic measurement system, and manual grading was recorded according to the International Knee Documentation Committee (IKDC) guideline. ResultsIn MRI, the ALL was identified in 104 patients (99.1%) and KF in 99 patients (94.3%). ALL and KF injuries were observed in 43 patients (43.9%) and 23 patients (23.5%), respectively. Patient distribution to each group was as follows; Group A: 43 patients (43.9%), Group B: 32 patients (32.7%), Group C: 12 patients (12.2%), Group D: 11 patients (11.2%). No significant differences were observed in tibial acceleration, and manual grading among the four groups. ConclusionSimultaneous injury to both ALL and KF was uncommon, and preoperative pivot-shift phenomenon did not increase even in those patients. The finding suggests that the role of ALL and KF in controlling anterolateral rotatory knee laxity may be less evident in the clinical setting compared to a biomechanical test setting.

Thermal analysis of a 3 T cryogen-free superconducting magnet for electromagnetic property measurement system

Thermal analysis of a 3 T cryogen-free superconducting magnet for electromagnetic property measurement system

Research on optimization technology of excitation coil in downhole annular flow electromagnetic measurement system

External interference and non-uniform velocity distribution influence the downhole annular flow electromagnetic measurement, reducing detection accuracy. Optimizing the structure of the excitation coil can effectively enhance the uniformity of magnetic field distribution, constituting an essential approach for improving measurement accuracy. Aiming at the excitation coil optimization technology of annular flow electromagnetic measurement system, the study first analyzes and obtains the magnetic field model of the excitation coil based on the principle of annular flow electromagnetic measurement, combined with the theory of vector weight function and puts forward the optimization theory of annular excitation coil. Secondly, the simulation models of rectangular and saddle exciting coils are established using finite element software to analyze the magnetic field distribution of annular flow under different coil and core sizes. The optimal structural parameters of the exciting coils in the annular flow electromagnetic measurement system are determined through evaluation indexes for the magnetic field. Finally, an experimental platform was established for optimizing the electromagnetic measurement of annular flow, and this platform was used to conduct comparative experiments. The experimental results show that the maximum reduction of the optimized system is 3.192%, 1.289%, and 1.813% for the single verification relative value error, single-point verification relative value error, and repeatability compared with the rectangular excitation coil annular flow electromagnetic measurement system. In the flow measurement interval of 25–100 m3 h−1, the single-point verification of the optimized system has a maximum relative display value error of 0.378%, and the measurement accuracy reaches 1.0 level and meets the consistency of the transmission of quantity and value. The research findings hold significant guidance for enhancing the measurement accuracy of the downhole annular flow electromagnetic measurement system.

Electromagnetic Detection System with Magnetic Dipole Source for Near-Surface Detection.

This paper proposes a nondestructive, separate transmitter-receiver (TX-RX) electromagnetic measurement system for near-surface detection. Different from the traditional dual-coil integrated design, the proposed transient electromagnetic (TEM) system performs shallow subsurface detection using independent TX coil and movable RX coils. This configuration requires a large primary field so that the far-away secondary field is able to generate reliably induced voltages. To achieve this goal, a bipolar current-pulsed power supply (BCPPS) with a late resonant charging strategy is designed to produce a sufficiently large magnetic moment for the exciting coil with low source interference. The magnetic dipole source (MDS) with a large proportion of weight is separated from the field observation device and does not need to be dragged or transported during the detection process. This setup lowers the weight of the scanning device to 3 kg and greatly improves the measurement efficiency. The results of the laboratory test verify the effectiveness of the separate MDS and RX module system. Field experimental detection further demonstrates that the proposed system can realize highly efficient and shallow surface detection within a 200 m range of the MDS device.

A Novel Bidirectional Flow Electromagnetic Measurement System for Drilling Engineering

A Novel Bidirectional Flow Electromagnetic Measurement System for Drilling Engineering

Asymmetric Calibration and Characterization for Diff-Port Magnetic Field Probing System

Strict symmetry limits the application of the differential port magnetic field probing system (DMPS). Asymmetric calibration is very meaningful for DMPS. Ultrawindband asymmetric calibration theory was first proposed and applied to the electromagnetic field measurement system. However, the asymmetric calibration theory is not clear for the DMPS because only magnetic field is concerned. This paper proposes an ultrawideband asymmetric calibration method (UACM) for the DMPS. The output voltage and asymmetric factor of the DMPS are redefined using the UACM. Compared with the previous asymmetric calibration method, the proposed method is based on a symmetry calibrator with grounded coplanar waveguide structure. The proposed method is validated by eliminating a severe asymmetry in the DMPS, whose severe asymmetry is achieved by introducing a connector intentionally. The proposed method has been verified with the frequency of up to 20 GHz by measuring a standing wave magnetic field on an open-terminated transmission line. The key parameters of the DMPS, including unwanted field suppression, spatial resolution, and sensitivity, are also estimated.

Optimization of electromagnetic flow measurement system based on a new mesh electrode

Electromagnetic flowmeter(EMF) is a common volumetric flow measurement instrument widely used in industrial flow measurement. With the development of EMF in the direction of high precision and intelligence, it is increasingly urgent to further improve the accuracy of EMF measurement. The key to reducing measurement error and eliminating the impact of interference noise is optimizing the electromagnetic flow sensor structure. Aiming at the existing EMF electrode optimization deficiencies, a new mesh structure electrode is firstly proposed in this paper. Then, a theoretical study on the distribution of virtual current density based on this mesh structure electrode is carried out, different structure electrodes are verified and analyzed through COMSOL finite element simulation, and the optimal structure design parameters of the new mesh electrode are obtained. Finally, an experimental platform is built, and a comparative experiment is conducted on the electromagnetic flow measurement system composed of the new mesh structure electrodes. The experimental results show that the maximum relative error of the optimized electromagnetic flow measurement system (OEMFS) is reduced by 0.47% compared with the ordinary EMF in the non-axisymmetric flow test. In the low-flow velocity test, the maximum relative error of the OEMFS is reduced by 7.46% compared with the ordinary EMF. In the strong interference test, the steady-state fluctuation of the amplitude of the OEMFS is reduced by 5.01% compared with the ordinary EMF. The OEMFS has better anti-interference, and the relative error of the system is less affected by the change in flow rate.

Research on Distributed Measurement and Control System Based on FlexRay Bus

With the purpose of the design problem of electromagnetic launch distributed measurement and control system, this paper proposes a design method of scalable large-scale distributed interconnected measurement and control system based on FlexRay bus. The task execution time deviation of each node in the distributed system, including phase deviation and frequency deviation, is reduced by using the macro tick generation process and clock synchronization process to achieve task synchronization in the distributed system. The synchronization of timing generation is realized based on the universal clock technology. When the timing interval is zero, the pulse power units are guaranteed to be close to the ideal full synchronization, thus ensuring that the released energy during transmission is close to the design value. In the state of adjustable timing, when the pulse power supply module conducts pulse discharge, the trigger discharge times of the modules are set according to the load needs. The flat top, sawtooth, and other characteristic current waveforms are adjusted accurately. At the same time, a combined multi-level protection structure based on hardware and software is realized. The verification results show that the distributed electromagnetic launch measurement and control system implemented in this paper can meet the high efficiency, fast and continuous launch target.

Steeper lateral posterior tibial slope and greater lateral-medial slope asymmetry correlate with greater preoperative pivot-shift in anterior cruciate ligament injury

PurposeTo investigate the association between posterior tibial slope (PTS) and preoperative pivot-shift phenomenon in anterior cruciate ligament (ACL)-injured knees.MethodsFifty unilateral ACL-injured patients (mean age: 28.0 ± 11.4 years, 29 males) who underwent ACL reconstruction were retrospectively included. Patients with a history of injury to the ipsilateral knee joint, concomitant ligament injuries with ACL injury, and/or more than one year from injury to surgery, were excluded. Pivot-shift tests were performed preoperatively under general anaesthesia using an electromagnetic measurement system, and tibial acceleration (m/s2) during the posterior reduction of the tibia was measured. Medial and lateral PTS (°) were measured respectively using high-resolution CT images taken two weeks after surgery. Lateral-medial slope asymmetry was calculated by subtracting medial PTS from lateral PTS (lateral-medial PTS) and we evaluated the correlation between each PTS parameter (medial PTS, lateral PTS, and lateral-medial slope asymmetry) and tibial acceleration during the pivot-shift test. The level of significance was set at p < 0.05.ResultsMedial PTS was 4.9 ± 2.0°, and lateral PTS was 5.2 ± 1.9°. The lateral-medial slope asymmetry was 0.3 ± 1.6° (range: -2.9 to 3.8). Tibial acceleration during the pivot-shift test in the ACL-injured knee was 1.6 ± 0.1 m/s2. Preoperative tibial acceleration was positively correlated with lateral PTS (r = 0.436, p < 0.01), and lateral-medial slope asymmetry (r = 0.443, p < 0.01), while no significant correlation was found between preoperative tibial acceleration and medial PTS (r = 0.06, p = 0.70).ConclusionPreoperative greater tibial acceleration during the pivot-shift test was associated with steeper lateral PTS and greater lateral-medial slope asymmetry in ACL-injured knees. These findings improve our understanding of anterolateral rotatory knee laxity by linking tibial bony morphology to quantitative measurement of pivot-shift phenomenon. Surgeons should be aware that not only lateral PTS but also lateral-medial slope asymmetry are the factors associated with preoperative pivot-shift.Level of EvidenceLevel IV.

Influence of Injury to the Kaplan Fibers of the Iliotibial Band on Anterolateral Rotatory Knee Laxity in Anterior Cruciate Ligament Injury: A Retrospective Cohort Study

Background: Biomechanical cadaveric studies have shown that Kaplan fibers (KFs) of the iliotibial band play a role in controlling anterolateral rotatory knee laxity in anterior cruciate ligament (ACL) injury. However, in the clinical setting, the contribution of injury to KFs on anterolateral rotatory laxity remains unclear. Purpose: To use magnetic resonance imaging (MRI) scans to detect concomitant KF injury in ACL-injured knees and to then examine the effect of KF injury on anterolateral rotatory laxity as measured by the pivot-shift test in a clinical setting. Study Design: Cross-sectional study; Level of evidence, 3. Methods: The study enrolled 91 patients with primary ACL tears (mean age 25 ± 11 years; 46 male and 45 female) whose MRI was conducted within 90 days after injury. KF injury was assessed by MRI according to previously reported criteria, and the patients were allocated to a KF injury group and a no–KF injury group. At the time of ACL reconstruction, the pivot-shift test was performed with the patient under anesthesia and quantitatively evaluated by tibial acceleration using an electromagnetic measurement system. Manual grading of the pivot-shift test was assessed according to guidelines of the International Knee Documentation Committee. The data were statistically compared between the 2 groups using Mann-Whitney U test and Fisher exact test (P < .05). Results: KFs were identified in 85 patients (93.4%), and KF injury was detected in 20 of the 85 patients (23.5%). No significant differences were observed between the KF injury group (n = 20) and the no–KF injury group (n = 65) in demographic characteristics, the period from injury to MRI (8.0 ± 14.0 days vs 8.9 ± 12.1 days, respectively), the rate of meniscal injury (50.0% vs 53.8%), or the rate of anterolateral ligament injury (45.0% vs 44.6%). Regarding the pivot-shift test, no significant differences were observed in tibial acceleration (1.2 m/s2 [interquartile range, 0.5-2.1 m/s2] vs 1.0 m/s2 [interquartile range, 0.6-1.7 m/s2], respectively) or manual grading between the 2 groups. Conclusion: Concomitant KF injury did not significantly affect the pivot-shift phenomenon in acute ACL-injured knees. The findings suggest that the contribution of KF injury to anterolateral rotatory knee laxity may be limited in the clinical setting.

Navigation guidance for ventricular septal defect closure in heart phantoms.

Transesophageal echocardiography (TEE) is the preferred imaging modality in a hybrid procedure used to close ventricular septal defects (VSDs). However, the limited field of view of TEE hinders the maneuvering of surgical instruments inside the beating heart. This study evaluates the accuracy of a method that aims to support navigation guidance in the hybrid procedure. A cardiologist maneuvered a needle to puncture the patient's heart and to access a VSD, guided by information displayed in a virtual environment. The information displayed included a model of the patient's heart and a virtual needle that reproduced the position and orientation of the real needle in real time. The physical and the virtual worlds were calibrated with a landmark registration and an iterative closest point algorithms, using an electromagnetic measurement system (EMS). For experiments, we developed a setup that included heart phantoms representing the patient's heart. Experimental results from two pediatric cases studied suggested that the information provided for guidance was accurate enough when the landmark registration algorithm was fed with coordinates of seven points clearly identified on the surfaces of the physical and virtual hearts. Indeed, with a registration error of 2.28 mm RMS, it was possible to successfully access two VSDs (6.2 mm and 6.3 mm in diameter) in all the attempts with a needle (5 attempts) and a guidewire (7 attempts). We found that information provided in a virtual environment facilitates guidance in the hybrid procedure for VSD closure. A clear identification of anatomical details in the heart surfaces is key to the accuracy of the procedure.

Design of an Electromagnetic Particle Velocity Measurement System Based on Superconducting Magnet

The electromagnetic particle velocity measurement technology is an important measurement method in the study of stress wave propagation. This paper analyzes the problem that the pulsed-magnetic-field-based electromagnetic particle velocity measurement technology will introduce additional induced electromotive force, and proposes an electromagnetic particle velocity measurement technology based on superconducting magnet. After considering the factors of electromagnetism, structure and heat distribution, a superconducting magnet with 500mm room-temperature bore was constructed, and the proposed electromagnetic particle velocity measurement system based on the superconducting magnet was designed subsequently. The experiment of filled explosion in PMMA was carried out, and high quality particle velocity and displacement signals were obtained, which verified the measurement performance of the system. The proposed method can provide a more powerful test means for the study of stress wave propagation.

Study on Electromagnetic Radiation Interference Caused by Rocket Fuel

During the launch and return of a spacecraft, the intense combustion of propellants generates strong electromagnetic radiation, which interferes with the operation of electronic equipment in the spacecraft. To improve the electromagnetic compatibility of electronic equipment in spacecraft, it is necessary to study the electromagnetic radiation characteristics of rocket fuel. An electromagnetic radiation measurement system based on antennas is designed to measure the electromagnetic radiation generated by rocket fuel, and the electromagnetic radiation characteristics are obtained through data analysis. The mechanism of the electromagnetic radiation generated by rocket fuel is comprehensively analysed through the spatial, time-domain, frequency-domain, and energy-domain characteristics. A characterization model is established to provide a reliable scheme for evaluating the influence of rocket fuel electromagnetic radiation on electronic equipment in spacecraft.

Research on small lightweight electromagnetic interference measurement system based on patrol unmanned aerial vehicle

Unmanned aerial vehicle (UAV) has been widely used in power system inspection. Most of the existing UAVs are equipped with visible and infrared cameras for fast full spectrum photography and fault monitoring of transmission lines. When the transmission line has defects such as aging, broken strand and serious corrosion, the traditional image recognition, infrared and other observation methods can not identify these defects well. In order to realize the rapid detection and judgment of broken strand, this paper analyzes the characteristics of electromagnetic interference of transmission line, and constructs the electromagnetic interference measurement system based on patrol UAV. The research results of this paper can realize the real-time detection and alarm of broken strand, and provide technical support for line inspection.

Research on Airborne Electromagnetic Whole-area Apparent Resistivity Imaging Algorithm in the Detection of Goaf in Rail Transit

Depth apparent resistivity imaging is an important process of data processing and analysis in the aviation transient electromagnetic method. It can provide reference value of conductor depth, vertical extension, and other information, and can accurately provide the measurement of each aviation transient electromagnetic measurement system. The structural section of the apparent conductivity of the one-dimensional layered medium on the line. As an advanced geophysical exploration technology, the aerial transient electromagnetic method has been applied significantly in the exploration of polymetallic minerals abroad in recent years. In this paper, based on the theory of ground-to-air transient electromagnetic method with multiple radiation sources, a corresponding multi-component global apparent resistivity definition method is established. The advantages of using the magnetic field strength to define the global apparent resistivity of the multi-radiation field source ground-air system are analysed. For each component of the magnetic field strength, respective global apparent resistivity algorithms are proposed to realize the multi-component, full-time, and full-space visual resistivity. The resistivity is calculated, and the influence of the offset on the global apparent resistivity is analysed. By adjusting the relative position of the source and the current direction and other parameters, the multi-radiation source transient electromagnetic ground-air system can not only strengthen the signal strength of different components, weaken random interference, but also better distinguish the location of underground anomalies

Probe method to measure the electromagnetic field in a plasma by Poynting vector conversion

In this paper, a high-precision electromagnetic measurement system suitable for a high-temperature and high-speed plasma is built to provide a platform for scientific research on the interaction mechanism of the electromagnetic fields and a plasma. This paper presents a method to measure the electromagnetic field inside a plasma by using a probe and Poynting vector conversion, which is a new and completely different method from the traditional method of measuring the electromagnetic field inside plasma. In addition, for this system and method, this work designs a microstrip antenna probe that can suppress multipath effects. This method is confirmed to be valid and usable after closed-loop verification by the CST software.

Design of heart phantoms for ultrasound imaging of ventricular septal defects.

Ventricular septal defects (VSDs) are common congenital heart malformations. Echocardiography used during VSD hybrid cardiac procedures requires extensive training for image acquisition and interpretation. Cardiac surgery simulators with heart phantoms have shown usefulness for such training, but they are limited in visualization and characterization of complex VSD. This study explores a new method to build patient-specific heart phantoms with VSD, with proper tissue echogenicity for ultrasound imaging. Heart phantoms were designed from preoperative imaging of three patients with complex VSDs. Each whole heart phantom, including atrial and ventricular septums, was obtained by manual segmentation and by surface reconstruction, then by molding and by casting in different materials. Heart phantoms in silicone and polyvinyl alcohol cryogel (PVA-C) were considered, and they were reconstructed in 3-D using 2-D freehand ultrasound imaging. An electromagnetic measurement system was used to measure the mean VSD diameters from the heart phantoms. Errors were evaluated below 1.0 mm for mean VSD diameters between 6.2 and 7.5 mm. Patient-specific heart phantoms promise for representing complex heart malformations such as VSDs. PVA-C showed better tissue echogenicity than silicone for VSDs visualization and characterization.

Development of a Cryogen-Free Compact 3 T Superconducting Magnet for an Electromagnetic Property Measurement System

A cryogen-free portable 3 T high-temperature superconducting magnet for an electromagnetic property measurement system has been developed to serve as a user facility at the Korea Basic Science Institute. The metallic insulation method was adopted to reduce the charging delay without sacrificing the self-protecting feature. A genetic-algorithm-aided optimized design was carried out to minimize the superconducting tape consumption while satisfying several design constraints. After the design, the compact high-temperature superconducting magnet composed of eight double-pancake coil modules was wound with high-temperature superconducting tape and stainless steel tape, and integrated with a two-stage cryo-cooler. The 3 T magnet was successfully cooled to approximately 20 K with a cryo-cooler and reached the target field of 3 T without any problems. Long-term measurements and a range of other tests were also implemented to verity the performance of the magnet. Test results demonstrated the feasibility of a cryogen-free portable high-temperature superconducting magnet system for electromagnetic property measurement experiments.