Omar Obeidat

As a simple and inexpensive channel characteristic, received signal strength (RSS) finds extensive usage in localization applications. However, the quick changes in signal strength impact the localization precision. By averaging over access points (APs) with multiple frequencies and/or heights, this article suggests a novel approach to lowering RSS fluctuation. Initially focused on the plane-earth loss model, the study was later extended to include a multipath indoor propagation scenario that was simulated. We used ray-tracing software to model the indoor propagation situation. This research takes into account the results of three distinct methods for averaging RSS: height averaging, frequency averaging, and hybrid frequency and height (FH) averaging, which combines the two. We discovered that the Height-only strategy considerably decreased the RSS variation with distance for both settings we looked at. Using the frequency-only method even further reduced the variation. Using the Hybrid FH technique greatly enhances the results. Root mean square error values of 4.427 dB, 3.70 dB, and 3.5 dB, respectively, are provided for the averaging approaches and the ideal scenario in which no variance occurs. Another finding is that averaging with APs that have double the height or frequency will not improve the RSS distance variation.

Sonic Infrared (SIR) Imaging is a novel hybrid NDE method that has seen rapid acceptance in the industry. SIR uses ultrasonic-generated heat as a defect detection mechanism. The ultrasonic excitation is a second or a fraction-of-a-second pulse in the 15 to 40 KHz range generated by a piezoelectric transducer which produces localized heating at the defect that will be captured by a

In this paper, experiment work and a three-dimensional thermo-mechanical coupled finite element model are purposed to study relationships of dependency energy consumption on transducer tip size as well as crack length in the crack area. Different crack length is experimented and simulated in this study. Their acoustic energy and thermal energy are obtained and analyzed to

Sonic infrared (SIR) imaging is an original hybrid nondestructive evaluation (NDE) technique that has seen rapid acceptance in the industry. A single-tone ultrasonic wave in the 15–40 kHz range is induced to the specimen under inspection through a high-power ultrasonic plastic welder. Heating duration is equal to the ultrasonic excitation duration. In a previous article, an analytical model for depth profiling using SIR NDE was presented. According to the proposed model, material thermal properties, defect size and ultrasonic excitation duration influence defect characterization and contribute to the total temperature-time curves. In this paper, heating duration effect on the quantitative estimation of flaws using sonic infrared nondestructive evaluation was investigated.

This paper outlines a study of the effect of changing the electrical properties of materials when applied in the Wireless InSite (WI) ray-tracing software. The study was performed at 60 GHz in an indoor propagation environment and supported by Line of Sight (LoS) and Non-LoS measurements data. The study also investigates other factors that may affect the WI sensitivity, including antenna dimensions, antenna pattern, and accuracy of the environment design. In the experiment, single and double reflections from concrete walls and wooden doors are analysed. Experimental results were compared to those obtained from simulation using the WI. It was found that materials selected from the literature should be similar to those of the environment under study in order to have accurate results. WI was found to have an acceptable performance provided certain conditions are met.

This paper introduces a study on verifying received power at WLAN frequencies in indoor environments, Wireless InSite is a popular electromagnetic ray-tracing software which is widely used for predicting channel behaviour in indoor and outdoor environments. The study compares software-generated data with measurements collected through 3rd floor Chesham Building, University of Bradford, at WLAN frequencies, the paper also investigates the effect of changing settings on results accuracy and computational time, and finally, the paper presents a comparison between simulation results with empirical models.

A comprehensive study of approaches to estimation of the local average of the received signal strength (RSS) for indoor multipath propagation is presented. The effects of the required number of RSS data samples and the Euclidean distances between neighbouring samples are investigated over 1D, 2D and 3D configurations. It was found that the effect of fast fading was reduced to an acceptable level using a 2D horizontal arrangement with a relatively large spacing configuration. Further, averaging was enhanced with larger spacing compared to small spacing, when considering the same number of samples.

Sonic Infrared Imaging (SIR) technology is a novel NDE method in NDE family. This technology is capable of detecting surface and subsurface defects in metals, metal alloys, and composites. SIR combines ultrasonic excitation with IR imaging to give a quick detection response in the crack region by observing the temperature change on the structure surface. Nonlinearity phenomena in SIR occur in the coupling between the target and ultrasound transducer, where a single frequency driving excitation source produces sound waves containing multiple frequencies. This nonlinearity is critical in improving the probability of crack detection significantly. In this paper, we will present our study on nonlinearity in SIR with emphasis on the relationship between the frequency of the induced sound waves and their corresponding energy consumption level in the crack vicinity of samples.

Sonic infrared (SIR) imaging is a hybrid nondestructive evaluation (NDE) method that uses ultrasonic excitation along with thermal imaging to detect defects in materials and structures. SIR NDE uses an ultrasonic pulse in the 15–40 kHz range from a transducer to produce localized heating at the defect while a thermal camera will record surface temperature during the inspection. In a previous article, we presented a model that describes heat diffusion from subsurface defects in a composite material. The model uses certain aspects of the temperature-time curve for defect depth profiling, namely, half-maximum power time, the peak slope time, and the second derivative peak time. In this study, we investigate the effect of defect size on the quantitative estimation of defect depth. The theoretical results are calculated and compared with the experimental data. We demonstrate that the experimental data have good correlation with the theoretical calculation. The peak slope time and the second derivative peak time are less sensitive to changes in defect size than the half-maximum power time in the defect depth assessment.