Error Assessment and Mitigation Methods in Transient Radar Method

Ospitia

et al. 2022

Sensors

Self Cite

Rubber is one of the most used materials in the world; however, raw rubber shows a relatively very low mechanical strength. Therefore, it needs to be cured before its ultimate applicatios. Curing process specifications, such as the curing time and temperature, influence the material properties of the final cured product. The transient radar method (TRM) is introduced as an alternative for vulcanization monitoring in this study. Three polyurethane-rubber samples with different curing times of 2, 4, and 5.5 min were studied by TRM to investigate the feasibility and robustness of the TRM in curing time monitoring. Additionally, the mechanical stiffness of the samples was investigated by using a unidirectional tensile test to investigate the potential correlations between curing time, dielectric permittivity, and stiffness. According to the results, the complex permittivity and stiffness of the samples with 2, 4, and 5.5 min of curing time was 17.33 ± 0.07 − (2.41 ± 0.04)j; 17.09 ± 0.05 − (4.90 ± 0.03)j; 23.60 ± 0.05 − (14.06 ± 0.06)j; and 0.29, 0.35, and 0.38 kPa, respectively. Further statistical analyses showed a correlation coefficient of 0.99 (p = 0.06), 0.80 (p = 0.40), and 0.92 (p = 0.25) between curing time–stiffness, curing time–permittivity (real part), and curing time–permittivity (imaginary part), respectively. The correlation coefficient between curing time and permittivity can show the potential of the TRM system in contact-free vulcanization monitoring, as the impact of vulcanization can be tracked by means of TRM.

Section: Summary and Discussionmentioning

confidence: 99%

A Novel Approach to Non-Destructive Rubber Vulcanization Monitoring by the Transient Radar Method

Ospitia

et al. 2022

Sensors

Self Cite

“…The amount of impact of each error source depends on the electronic specifications as well as geometric and EM properties of the SUT. For instance, when the thickness of the sample under investigation is relatively lower than the wavelength, the divergence error [20] can be neglected. However, for such kind of SUT which is of homogeneous thin single-layer structures, only one considers the following important error sources.…”

Section: Error Mitigationmentioning

confidence: 99%

“…Furthermore, the angle between the transmitter and receiver antenna can potentially lead to an increasing RTT in the body of sample. Additionally, the EM properties must be calculated based on the polarization of the incident wave in Fresnel equations [20]. Finally, the finite conductivity of PSMR at 24 • C should be considered as well [20].…”

Section: Error Mitigationmentioning

confidence: 99%

See 1 more Smart Citation

Fully Blind Electromagnetic Characterization of Deep Sub-Wavelength (λ/100) Dielectric Slabs With Low Bandwidth Differential Transient Radar Technique at 10 GHz

IEEE Trans. Microwave Theory Techn.

Stiens

2022

Self Cite

Transient radar method (TRM) is introduced as a novel non-destructive testing (NDT) technique that is capable of analyzing fully blindly and simultaneously the electromagnetic (EM) properties as well as geometric parameters of deep sub-wavelength thin single layer slabs. This study focuses on the minimum detectable layer thickness by means of TRM, which mainly depends on the experimental setup configuration. In this article, the complex permittivity and thickness of three polyvinyl chloride (PVC) sheets are extracted by means of a differential TRM set-up. The thickness of these PVC sheets was 1 mm, 500 μm, and 300 μm that corresponded to λ/30, λ/60, and λ/100, respectively (λ is the wavelength in free space). The carrier frequency was 10 GHz and the experiments were done in a bistatic radar setup. A differential TRM structure was used in this experiment. Some error sources, such as switch leakage and non-perpendicular illumination as well as systematic errors are considered as well. The experimentally obtained results are as follows: the thickness of these samples were 1033 ± 12, 535 ± 11, and 302 ± 9 μm with 1.18%, 0.94%, and 2.89% relative error, respectively. Additionally, the complex permittivity of these samples was found as (2.73 ± 0.02)-(0.23 ± 0.01)j, (2.70 ± 0.02)-(0.20 ± 0.02)j, and (2.65 ± 0.02)-(0.37 ± 0.01)j, respectively. This novel technique has the potential for deployment in a wide range of applications ranging from the piping, wind energy industry, and automotive to biotechnology, food industry, clinical monitoring, and pharmacy.

“…Transient radar method (TRM) can be considered as a sub-group of time-domain microwave reflectometry methodology which deals with the transient part of the reflection signal from the sample under test rather than using its steady-state form [ 12 ]. Since IAP elevation influences the mechanical, geometric, and electromagnetic properties of the abdominal wall, this radar-based technique is able to track IAP fluctuations and changes as it is able to extract electromagnetic and geometric properties of the sample under investigation without any prior knowledge [ 13 ].…”

Section: Introductionmentioning

confidence: 99%

Non-Invasive Intra-Abdominal Pressure Measurement by Means of Transient Radar Method: In Vitro Validation of a Novel Radar-Based Sensor

Malbrain

et al. 2021

Sensors

Self Cite

Intra-abdominal hypertension, defined as an intra-abdominal pressure (IAP) equal to or above 12 mmHg is one of the major risk-factors for increased morbidity (organ failure) and mortality in critically ill patients. Therefore, IAP monitoring is highly recommended in intensive care unit (ICU) patients to predict development of abdominal compartment syndrome and to provide a better care for patients hospitalized in the ICU. The IAP measurement through the bladder is the actual reference standard advocated by the abdominal compartment society; however, this measurement technique is cumbersome, non-continuous, and carries a potential risk for urinary tract infections and urethral injury. Using microwave reflectometry has been proposed as one of the most promising IAP measurement alternatives. In this study, a novel radar-based method known as transient radar method (TRM) has been used to monitor the IAP in an in vitro model with an advanced abdominal wall phantom. In the second part of the study, further regression analyses have been done to calibrate the TRM system and measure the absolute value of IAP. A correlation of –0.97 with a p-value of 0.0001 was found between the IAP and the reflection response of the abdominal wall phantom. Additionally, a quadratic relation with a bias of −0.06 mmHg was found between IAP obtained from the TRM technique and the IAP values recorded by a pressure gauge. This study showed a promising future for further developing the TRM technique to use it in clinical monitoring.