Search

This research investigates the characterization of bituminous mixes utilizing microwave imaging and non-destructive testing. We studied the electromagnetic characteristics of various samples, including bituminous concrete (BC) and open-grade friction course (OGFC) samples. A novel ring filter with log-periodic feedlines, designed on the RT/Duroid 5880 substrate, was utilized within the frequency range of 0.3–0.7 GHz. The samples were assessed using average attenuation and group delay measures, which detailed clear electromagnetic characteristics. The samples' flow value and specific gravity were correlated to these parameters. The calculated flow value and specific gravity (using the filter) and measured flow value and specific gravity (using the conventional method) coincided well. The filter could predict the parameters of the samples with a high accuracy of roughly 99.8% for the flow value and specific gravity, whereas the OGFC sample displayed an accuracy of 99.7%, correspondingly, as shown in high R2 values. This demonstrates that the filter can precisely measure the parameters required for studying the interaction between the binder and aggregate in bituminous mixes without being invasive. The findings indicate a significant disparity between OGFC and BC samples in their responses to electromagnetic fields and their characteristics. This demonstrates the high sensitivity and significant value of microwave techniques in the study of bitumen and the construction of roadways. [ABSTRACT FROM AUTHOR]

In this paper, behavioral modeling of a driver amplifier is implemented by using S2P and S2D model setup. By using the standard silicon-based driver amplifier for obtaining the measured results of Scattering (S)- parameters and large signal parameters for temperatures 25°C and 85°C. These parameters are imported into the S2P and S2D models to perform the small signal and large signal analysis at 3 GHz frequency for temperatures 25°C and 85°C. Then, the simulated results are compared with the measured results to verify the efficient utilization of behavioral models. The novelty of this work deals with the simulation study of the characteristics of a silicon-based driver amplifier, which are obtained directly from the measurements. This proposed method is essential for performing hetero-integration of transceiver design, which can be further utilized to improve the efficiency of transceiver for high-frequency band. At last, the study of relative error performance analysis between measured and simulated results of different parameters is carried out and calculated value of NMSE (in %) for S11, S12, S21, S22, gain, pout, 1 dB compression point, ACP, 3rd harmonics, 4th harmonics, and 5th harmonics are 0.0083, 0.0055, 0.0086, 0.011, 0.0844, 0.814, 0.926, 0.71, 0.22, 0.012 and 0.070 respectively. [ABSTRACT FROM AUTHOR]

In this paper, a study on the effects of strategically implemented holes in a miniaturized wideband bandpass filter (BPF) utilizing interdigital folded coupled lines is presented. First, the BPF is designed to produce the passband by introducing a fold in the coupled lines. The passband is centered at 9.3 GHz (X‐band), catering to radar applications. Coupled lines connected to a modified U‐shaped transmission line comprise the filter's design configuration. The novelty of the design resides in incorporating drilled holes along the coupled lines, which generate perturbations and resonant effects, resulting in enhanced impedance variations and improved filter performance. With the aid of electromagnetic analysis and simulation software, the coupled lines, U‐shaped transmission lines, and drilled hole diameters are all optimized. Vector Network Analyzer performs all the measurements and draws the comparisons. An increment of 22.58% is seen in return loss as it increases from −24 to −32 dB, and the insertion loss shows an increase of 16.74%. The proposed filter has been subjected to analytical study, simulation, and implementation, which have confirmed its exceptional return loss, favorable insertion loss, and compact dimensions. The research results make a valuable contribution to the development of miniaturized wideband BPFs, specifically focusing on their use in radar systems. In such systems, the ability to accurately and efficiently filter signals is paramount. The design insights and performance improvements presented in this study have significant implications for broader applications in microwave engineering and communication systems. [ABSTRACT FROM AUTHOR]

Air quality (AQ) monitoring is crucial for maintaining human health and well-being, whether outdoors or indoors. Particulate matter (PM) is among the most critical parameters that must be routinely monitored. Traditional reference particulate analyzers are expensive and difficult to deploy on a large scale, leading to poor spatial and temporal AQ information. However, the reliability and accuracy of these sensors are yet to be established. This study is aimed at assessing the performance of five low-cost sensors by comparing them with a particulate reference analyzer for AQ monitoring in accordance with the United States Environmental Protection Agency (US EPA)-recommended guidelines. The sensors were tested for indoor and outdoor environments using simple linear regression (SLR) models. The results indicate that low-cost sensors are unreliable for accurately measuring AQ in indoor environments. The correlation between the sensors and the reference analyzer was poor, with coefficient of determination (R²) values ranging from 0.2 to 0.58 during the three-week analysis period for a 1-h average. However, after increasing the average time interval, the sensor (HPMA115) satisfied the US EPA-recommended guideline with an R² value of 0.72. Root-mean-square error (RMSE) values for some sensors exceeded the US EPA guideline of less than 7 μgm−3 for PM sensors. The concentration of PM2.5, indoor relative humidity (RH), and temperature were identified as potential factors contributing to sensor behavior. The air conditioning system also affected the sensor performance, with variations in RH and temperature observed between tests with and without occupants. The results showed that low-cost sensors could be utilized for outdoor environments, with Honeywell’s HPMA115 performing well. However, the calibration process must be performed for each specific environment. Our findings highlighted the limitations of low-cost sensors for AQ monitoring and the need for further research to develop reliable sensors. [ABSTRACT FROM AUTHOR]