Circularly polarized printed dual port MIMO antenna with polarization diversity optimized by machine learning approach for 5G NR n77/n78 frequency band applications.

In this communication, a planar dual port multiple input multiple output antenna of size 1.2λ0 × 0.6λ0 × 0.008λ0 with LHCP/RHCP features is reported for the fifth-generation new radio n77/n78 sub-6 GHz wireless applications band. The single unit of the proposed design consists of a modified L-shape rectangular radiator with Z-shape slot loaded DGS. The defected ground structure is optimized through machine learning algorithms to achieve the maximum ARBW (output) by Right Shifting (RS) and left shifting (LS) the DGS and obtaining input features. The performance metric for ANN with ADAM optimizer was found to be optimal with MSE and R2 of 0.99 and 0.82, respectively. ANNs can leverage gradient information to guide the optimization process. This enables faster convergence towards optimal solutions compared to popular GAs and PSO, which are often gradient-free optimization methods. The MIMO configuration is achieved by creating a mirror image of the single unit about the x-axis. The salient features of the proposed design are (a) Impedance bandwidth (IBW) of 3.0-4.2 GHz covering the n77/n78 band, (b) 3-dB axial ratio bandwidth (ARBW) of the 2.6-3.9 GHz (c) Port-1 is generating RHCP while Port-2 is generating LHCP, results in polarization diversity. Different diversity performance parameters (ECC < 0.005, DG ~ 9.99 dB, and MEG < 3 dB) are in the optimum range confirming the proposed configuration as a suitable design for a MIMO radiator.

Efficient graphene-based circularly polarized MIMO antenna for THz applications.

In this paper, a graphene-based (MIMO) antenna is designed and examined. Two unique properties of the proposed terahertz (THz) MIMO antenna are (1) circular polarization is achieved through an asymmetrical cross slot, etched over the graphene patch; and (2) a bidirectional radiation pattern is achieved through oppositely oriented identical antenna ports. Mutual coupling between the antenna ports is less than -35dB. Due to the inclusion of the pattern diversity concept, a low value of envelope correlation coefficient is achieved. The proposed THz radiator operates over the frequency range of 4.67-4.87 THz, along with a 3 dB axial ratio between 4.76 and 4.81 THz. This type of antenna is widely employable for biomedical applications.

Biotic control of harmful algal blooms (HABs): A brief review.

The water bodies, mainly coastal and lake, remain tainted worldwide, mostly because of the Cyanobacteria harbored in Harmful Algal Blooms (HABs). The main reason for the flourishing of blooms depends on the eutrophication. Blooms could be toxic as well as non-toxic, depending on the bloom-forming species. The blooms affect the water body, aquatic ecosystem and also dependents like human. A large number of organisms, including bacteria, viruses, fungi, fish and zooplankton have adverse effects on Cyanobacteria either through infection, predation or by the production of the algicidal compounds. It was reported, these microorganisms have species-specific interactions and hence differ in their interaction mechanism. The present review emphasises on the role of selected microbial species and the mechanism they follow for mitigation of HABs. Generally lab-scale entities were reported to involve lytic agents, like cyanobacteriolytic substances, released by bacteria. Cyanobacterial species release Cyanotoxins which may affect the water quality. Growing biotic factors in a large quantity and discharging it into the water-body needs excessive efficacy and economic requisite and hence the feasibility of extrapolation of the laboratory results in the field still finds promiscuity towards mitigation of HABs.

Use of water quality index and multivariate statistical techniques for the assessment of spatial variations in water quality of a small river.

Rapid urban development has led to a critical negative impact on water bodies flowing in and around urban areas. In the present study, 25 physiochemical and biological parameters have been studied on water samples collected from the entire section of a small river originating and ending within an urban area. This study envisaged to assess the water quality status of river body and explore probable sources of pollution in the river. Weighted arithmetic water quality index (WQI) was employed to evaluate the water quality status of the river. Multivariate statistical techniques namely cluster analysis (CA) and principal component analysis (PCA) were applied to differentiate the sources of variation in water quality and to determine the cause of pollution in the river. WQI values indicated high pollution levels in the studied water body, rendering it unsuitable for any practical purpose. Cluster analysis results showed that the river samples can be divided into four groups. Use of PCA identified four important factors describing the types of pollution in the river, namely (1) mineral and nutrient pollution, (2) heavy metal pollution, (3) organic pollution, and (4) fecal contamination. The deteriorating water quality of the river was demonstrated to originate from wide sources of anthropogenic activities, especially municipal sewage discharge from unplanned housing areas, wastewater discharge from small industrial units, livestock activities, and indiscriminate dumping of solid wastes in the river. Thus, the present study effectively demonstrates the use of WQI and multivariate statistical techniques for gaining simpler and meaningful information about the water quality of a lotic water body as well as to identify of the pollution sources.