We report the detection of ammonia gas through electronic and transport properties analysis of boron nitride sheet. The density functional theory (DFT) based ab initio approach has been used to calculate the electronic and transport properties of BN sheet in presence of ammonia gas. Analysis confirms that the band gap of the sheet increases due to presence of ammonia. Out of different positions, the bridge site is the most favorable position for adsorption of ammonia and the mechanism of interaction falls between weak electrostatic interaction and chemisorption. On relaxation, change in the bond angles of the ammonia molecule in various configurations has been reported with the distance between NH3 and the sheet. An increase in the transmission of electrons has been observed on increasing the bias voltage and I-V relationship. This confirms that, the current increases on applying the bias when ammonia is introduced while a very small current flows for pure BN sheet.
A miniaturized U-shape patch sensor (15 mm × 15 mm) was designed at dual resonating frequencies (f r) 5.2 GHz and 6.8 GHz. The proposed design printed on FR4 material with a thickness of 1.676 mm and relative permittivity 4.4. To simulate the performances of the proposed design, the CST Microwave Studio (CST MWS) was used. The reflection coefficient of U-shape patch sensor was measured. Basmati rice was investigated, and bulk density was increased with increase of moisture content, hence varied from 554.3 to 591 kg/m 3. It has the longest average rice length (L) 7.2 mm, average width (W) 1.61 mm, and L/W ratio 4.47. The percentage of moisture was varied from 10.71% to 21.87% calculated on a wet weight basis. The lowest mean relative error (MRE) determined between predicted moisture content (PMC) and actual moisture content (AMC) was 0.55% at dual frequencies.
Microstrip patch sensor was designed for resonant frequency (fr) 8.1 GHz, printed on FR4 material thickness of 1.676 mm, and relative permittivity was 4.4. For simulation, CST Microwave Studio was used. The aim was to measure the moisture content (MC) of basmati rice whose various properties were longest average rice length (L) 7.2 mm, average width (W) 1.61 mm, L/W ratio 4.47, and bulk density was varied from 554.3 to 591 kg/m3 (bulk density was increase with increase of MC). For checking the working performance of design sensor, predicted moisture content (PMC) and actual moisture content (AMC) were compared. In the former case, reflection coefficient of overlaid rice was measured from vector network analyzer; PMC obtained was varied from 10.53% to 21.67%. In latter case, AMC was varied from 10.71% to 21.87%. Therefore, the lowest mean relative error (MRE) was 1.86% at 8.1 GHz. Hence, the proposed sensor was found to be more accurate than previous designs.
A four-element wide-band octagonal ring-shaped antenna is proposed for human interface device and S-band applications. The isolation structure comprises a parasitic element and a T-shaped structure. The antenna has −10 dB impedance bandwidth 63% (2.1–4.0 GHz) with miniaturized dimension of 54.98 mm × 76 mm. The multiple input multiple output (MIMO) antenna gain is 2.83 dBi at the 2.4 GHz resonant frequency. The designed MIMO has envelop correlation coefficient of 0.026 in the 2:1 VSWR band. The −10 dB total active reflection coefficient bandwidth of 1.2 GHz has been achieved in the entire frequency band, and has MEG value of ≤−3 dB. The specific absorption rate has found below the safety limit near the human head, palm and wrist.
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