The relative share of renewable energy, specifically the solar photovoltaic (PV), is increasing exponentially in the world electric energy sector. This is a cumulative result of reduction in the cost of solar panels, improvement in the panel efficiency, and advancement in the associated power electronics. Among different types of PV plants, installation of small-scale rooftop PV is growing rapidly due to direct end-user benefits and lucrative governmental incentives. There are various standards developed in regards to grid integration of PVs and other distributed generations (DGs). Different power converter topologies are developed to interface the PV panel with the utility grid. To keep up with the stringent regulations imposed by the standards, various control strategies and grid synchronization methods have been developed. This review article amalgamates and summarizes all of the aforementioned aspects of a grid-integrated PV system including various standards, power stage architectures, grid synchronization methods, operation under extreme events, and control methodologies, pertaining to small-scale PV plants. This article will help freshman researchers to gain some familiarity with the topic and introduce them to some of the key issues encountered in this field.

Four element (2 × 2) planar multi-input multi-output (MIMO) antenna design is proposed for long-term evolution applications for operating bands 1 and 4. The design combines 180° phase reversed and phase rotated antenna elements. Presented design integrates the effect of pattern and space diversity techniques for common return-losses and isolations at different (or between) ports. The fabricated antenna utilizes the space of 68 × 98 mm² on low cost FR-4 dielectric substrate. The proposed design with VSWR of <2 exhibits −10 dB impedance bandwidth in the range of 1.66–2.17 GHz. More than 10 dB of isolation among all the radiating elements of MIMO is recorded in simulation and measured cases. The measured peak gain in considered frequency spectrum is better than 2.5 dBi. The diversity performance explores the effect of peak gain, envelope correlation coefficient (ECC), mean effective gain, and directivity on the presented design.

In this paper, we present an unsupervised model-based decomposition technique for the analysis of hybrid-pol datasets. The proposed approach develops a hybrid-pol version of full-pol three-component scattering model by deriving all decomposition parameters in terms of the hybrid-pol Stokes parameters. By using these decomposition parameters, the contribution of three basic scattering mechanisms, namely surface-scattering from Bragg surface region, dihedral-scattering from urban region and volume-scattering from forest region, are estimated. The decomposition parameters take surface dielectric properties under consideration that makes the proposed method suitable to provide more realistic representation of the Earth's surface. To estimate the efficacy of the proposed technique, the hybrid-pol data acquired over Mumbai city using ISRO's RISAT-1 satellite is used. For comparative analysis, the proposed technique is compared with the conventional decomposition techniques, such as $m-\delta$, $m-\dot{\alpha }$, and modified $m-\chi$ .

Elastomer is an electroactive polymer, which finds popular application in the field of actuators and artificial muscles. Though elastomers are popularly used as actuators, with proper modification to their operating cycle, they can also be used as generators. These dielectric elastomer generators (DEGs), due to properties such as high energy density and frequency independent operation are suitable for different energy harvesting applications. In this letter, a simplified electrical model of the DEG is proposed, which can be used in various simulation platforms to verify compatibility of DEG with electrical circuits and predict its behavior. Detailed process of deriving the model parameters from a physical DEG is discussed at length. Performance of the proposed model is verified by comparing its behavior with a prototype DEG-based energy harvesting system having a DEG of 1.3 nF capacitance. The proposed DEG model was simulated with similar conditions and the simulation results have shown good accuracy with the experimental results.

A new dielectric constant estimation approach for the lunar surface using Mini-RF synthetic aperture radar (SAR) data and Chandrayaan-2 SAR data is presented in this work. Both the SAR systems are based on a hybrid-polarimetry (hybrid-pol) configuration that transmits a circularly polarized wave and coherently measures the backscattered wave by dual orthogonal linearly polarized channels. From the three-component hybrid-pol SAR decomposition technique, the ratio of the Fresnel reflection coefficients for horizontal and vertical polarization transmission can be estimated. This ratio, which is referred to as the co-polarization ratio, is used by the proposed methodology to find the real value of the dielectric constant. For performance validation, the proposed method is implemented on the Mini-RF hybrid-pol SAR data acquired over Apollo 17 landing sites. The values of the real part of dielectric constant are estimated for six different regions covering the collection sites of six Apollo 17 samples: 72 441, 73 241, 74 241, 75 081, 76 001, and 79 135. The results obtained using the proposed method are found to be in good agreement with the laboratory-measured results of the corresponding samples. Furthermore, the proposed methodology is also implemented on the Chandrayaan-2 hybrid-pol SAR data acquired over the Biot crater region. Various small areas possessing different possible surface characteristics, situated inside and outside the Biot crater , are being analyzed for validation.

In this letter, a special unitary SU(3) matrix group is exploited for coherency matrix transformations to decouple the energy between orthogonal states of polarization. This decoupling results in the minimization of the cross-polarization power along with the removal of some off-diagonal terms of coherency matrix. The proposed unitary transformations are utilized on the basis of the underlying dominant scattering mechanism. By doing so, the reduced power from the cross-polarization channel is always concentrated on the underlying dominant co-polar scattering component. This makes it unique in comparison to state-of-the-art techniques. The proposed methodology can be adopted to optimize the coherency matrix to be used for the model-based decomposition methods. To verify this, pioneer three-component decomposition model is implemented using the proposed optimized coherency matrix of two different test sites. The comparative studies are analyzed to show the improvements over state-of-the-art techniques.