http://nopr.niscpr.res.in/handle/123456789/63 Mon, 05 Oct 2026 09:41:39 GMT 2026-10-05T09:41:39Z https://http://nopr.niscpr.res.in:443/retrieve/200086/IJPAP 64(05) Cover Page.png http://nopr.niscpr.res.in/handle/123456789/63 http://nopr.niscpr.res.in/handle/123456789/68440 Title: Odd-Even Staggering in Gamma Vibrational Bands of Deformed Nuclei Insights from Collective Models and Machine Learning Approaches Authors: Sharma, Pooja; Bindra, Amit Abstract: The odd-even spin staggering of gamma-vibrational bands is examined for even-even Gd isotopes in the rare-earth region. The work uses experimental gamma-band energies, the empirical staggering index S(J), the energy ratio R4/2, and the asymmetry parameter gamma0 to follow the evolution from gamma-soft behaviour toward more axially deformed rotational structures. The analysis is framed by collective-model ideas, especially the interacting boson model and the triaxial rotor picture, because both connect gamma-band level splitting with the softness or rigidity of the nuclear shape. A LightGBM regression procedure is further used only as a data-support tool for the missing S(7) and S(8) entries at N = 94. The imputed values are inserted with uncertainty estimates so that the observed trend of the Gd chain can be discussed without leaving artificial gaps in the systematics. The results show strong staggering near the transitional neutron numbers and a close relation between S(J), R4/2 and asymmetry parameter 𝛾􀬴. These observations support the view that gamma-band staggering is a sensitive indicator of triaxial effects, shape evolution and symmetry changes in deformed nuclei. Page(s): 955-960 Tue, 01 Sep 2026 00:00:00 GMT http://nopr.niscpr.res.in/handle/123456789/68440 2026-09-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/68439 Title: Harmonic Minimization using a Cascaded Multilevel Converter for a Standalone Renewable Energy System Authors: Gupta, Ranitesh; Sahay, Kuldeep Abstract: Effective power conversion is necessary when integrating photovoltaic (PV) systems into the electrical grid to manage high voltages, minimize switch stress, and improve power quality while reducing the need for intensive filtering. The advantages of multilevel inverters (MLIs), especially cascaded H-Bridge (CHB) designs, in lowering electromagnetic interference (EMI) and increasing efficiency have made them essential for renewable energy systems. This work proposes a DC-AC-DC-AC converter system with seven-level and thirteen-level topologies. The seven-level converter system is designed and simulated in MATLAB/Simulink using phase-shifted pulse-width modulation (PSPWM) and level-shifted pulse-width modulation (LSPWM) to analyze total harmonic distortion (THD) and determine the best modulation technique for a grid-connected standalone system. The study finds that the thirteen-level converter showed improved power quality and system efficiency, with a significant decrease in THD to 0.43 % after filtering. Real-time simulation on the OPAL-RT platform confirms the adaptability and efficacy of the presented approach in real-world situations. Furthermore, incorporating more reliable and compact medium-frequency transformers supports environmental sustainability by enhancing energy efficiency, reducing material consumption, and supporting modularity for easier maintenance. Page(s): 961-971 Tue, 01 Sep 2026 00:00:00 GMT http://nopr.niscpr.res.in/handle/123456789/68439 2026-09-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/68438 Title: Adaptive Metaheuristic Optimization of Frequency-Selective Multi-band Antennas for Enhanced Electromagnetic Performance Authors: Palanisamy, SatheeshKumar; Sathishkumar, N; Mahapatra, Sheila; Kandasamy, Jeevitha Abstract: With advanced wireless systems gaining market traction, there is a need for small, high-performance antennas. Design strategies must be efficient and accurate so antennas can operate across multiple bands with good gain and impedance matching. This study presents a flexible metaheuristic optimization methodology for designing a multi-band antenna with Frequency Selective Surfaces (FSS). The design process involves the step-by-step evolution of its FSS unit cell, starting from a circular structure followed by an annular ring and an adyne triangular protrusion to enhance resonance characteristics and surface current distribution. The rectangular patch with its rectangular protrusions forms the key radiating component of the antenna at the end. An evolved frequency-selective surface (FSS) cell improves frequency selectivity and gain. The Adaptive Enhanced Diversified Hiking Optimization Algorithm (AEDHOA) achieves a good trade-off between exploration and exploitation, with accelerated convergence and improved optimization accuracy. Simulations and experiments both show that far-field radiation performance improves significantly when FSS elements are added to the radiating surface. At 3.8 GHz, the antenna with FSS under the patch achieves a return loss of −53 dB, a VSWR of 1.3, and a gain of 4.01 dBi. Compared with traditional methods, the AEDHOA reduces computation iterations by 35 % and increases the fitness value by 27 %. This work demonstrates a scalable and computationally efficient design approach for multi-band antennas suitable for next-gen wireless, IoT, and radar applications. Page(s): 972-983 Tue, 01 Sep 2026 00:00:00 GMT http://nopr.niscpr.res.in/handle/123456789/68438 2026-09-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/68437 Title: Polar Resistors Asymmetric Semiconductor Structures as Linear Resistors with Different Resistances for Opposite Polarities Authors: N Roy Choudhury, Aditya Abstract: Passive, two-terminal resistors, with linear current voltage relationships, but exhibiting different resistances for opposite polarities are introduced in this paper. Such resistors change their resistance when current direction through them changes. These are named polar resistors. Such polar resistance is observed in asymmetric semiconductor INI structures, where I is an abbreviation for intrinsic, and N is for n-type doped. Polar resistance is not material specific. Both Silicon and Gallium Arsenide polar resistors were simulated in this work. In a three-layered INI structure, for certain thicknesses of the intrinsic layers, it is observed that for positive voltage, voltage drops significantly across one intrinsic layer, and for negative voltage, voltage drops significantly across the other intrinsic layer. With different I-layer thicknesses polar resistance is achieved. A background mobile electronic concentration of 1011/cc and 1012/cc were assumed for Si, due to background doping, and 107/cc and 108/cc were assumed for GaAs. Metallic ohmic contacts to semiconductor intrinsic layers are difficult to fabricate. So doped n-type CdS and SnO2 were used as contact enabling layers to Si and GaAs respectively. This implies the structure is NININ; i.e. N-CdS/I-Si/N-Si/I-Si/N-CdS and N-SnO2/I-GaAs/N-GaAs/I-GaAs/N-SnO2. In such devices, between -1V and +1V, polar resistance is observed and a rectification ratio up to 10 are demonstrated. The roles of the middle N layer and the n-type contact enabling layers are also discussed. Page(s): 984-997 Tue, 01 Sep 2026 00:00:00 GMT http://nopr.niscpr.res.in/handle/123456789/68437 2026-09-01T00:00:00Z