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Electrical, mechanical, and energy harvesting of a pyroelectric polymer nanocomposite
Panwar Lokesh Singh,Panwar Varij,Ansari Mohd Umer,Anoop Gopinathan,Park Sukho 한국물리학회 2023 Current Applied Physics Vol.52 No.-
Flexible pyroelectric devices can convert waste heat from the human body, sun, industry, geothermal, and automobiles into renewable electricity. In this paper, carbon nanofiber (CNF) and poly(2-acrylamide-2-methyl-1- propane-sulfonic acid) and PAMPS attached poly(vinylidene fluoride) (PVDF) pyroelectric polymer nanocomposite (PyPNC) were investigated for electrical, mechanical, and pyroelectric performance with temperature variations. The ac conductivity and open circuit voltage of PyPNC increased with temperature. The PyPNC showed the enhanced AC conductivity (σac) of 89 S/cm and open circuit output voltage of 4.8 V at 120 ◦C due to the alignment of CNF with PAMPS beads that enhanced the volume fraction of the β-phase in PyPNC at 120 ◦C than that of the random orientation of CNF with PAMPS beads of PyPNC at 20 ◦C, 50 ◦C, and 150 ◦C.
Novel optimization method of single square FSS impinged and cascaded radar absorbing composites
Panwar, Ravi,Son, Dae-Sung,Lee, Jung-Ryul VSP 2018 Advanced Composite Materials Vol. No.
<P>It is well known that radar absorbing potentiality of existing magneto-dielectric composites can be significantly enhanced by the application of frequency selective surface (FSS) and cascaded electromagnetic (EM) structures. But the optimization of such complex EM structures and validation of the adopted optimization strategy is still a very challenging task for the researchers. Therefore, in this study, an effective effort has been made for the optimization and the corresponding validation for Single Square FSS (SS-FSS) impinged and cascaded radar wave absorbers using advanced computational EM software's like FEldberechnung furKorper mit beliebigerOberflache - a German acronym (FEKO) and high frequency structure simulator (HFSS). In addition, a critical analysis of dielectric constant (epsilon) has been carried out to select the best combination of composites for the development of efficient radar wave absorbers. A comparison between optimized and simulated results have been carried out to examine the effect of advanced EM approaches over reflection loss (RL) characteristics of composite radar absorbing materials (CRAMs). A rapid change in radar absorption properties of composites has been observed after the application of SSFSS and cascading. A SS-FSS impinged composite has been found to provide a wide absorption bandwidth of 3.6GHz at X-band. A cascaded absorber having layer thickness 1.8mm provides a peak RL of -42.6dB at 10.6GHz with an absorption bandwidth of 2.5GHz. The strong agreement between mathematical model, HFSS and FEKO results clearly reflects the efficiency of adopted approach for distinct practical EM applications.</P>
Stimulated Raman forward scattering of laser in a pre-formed plasma channel
Panwar, Anuraj,Kumar, Ashok,Ryu, C.M. Cambridge University Press 2012 Laser and particle beams Vol.30 No.4
<B>Abstract</B><P>Stimulated Raman forward scattering (SRFS) of an intense short pulse laser in a plasma channel formed by two pre-laser pulses is investigated. The density nonuniformity of a plasma channel increases the focusing of main laser pulse. Main laser pulse excites a plasma wave and two electromagnetic sideband waves. Laser and the sidebands exert an axial ponderomotive force on electrons driving the plasma wave. The nonlinear currents arise at sideband frequencies. The density perturbation due to plasma wave beats with the oscillatory velocity due to pump to drive the sidebands. The normalized growth rate of SRFS increases with the density nonuniformity of a plasma channel. However, in the presence of a deep plasma channel the focusing is ineffective to laser intensity, but the growth rate increases with the intensity of main laser pulse.</P>
Modulational instability of a laser pulse in a non-uniform plasma channel
Panwar, Anuraj,Ryu, Chang-Mo,Kumar, Ashok Cambridge University Press 2016 Laser and particle beams Vol.34 No.1
<B>Abstract</B><P>A self-guided Gaussian laser pulse propagating in a non-uniform plasma channel is unstable to a plasma wave perturbation co-moving with the laser with its group velocity. The plasma wave amplitude has a maximum radial profile along the laser propagation axis. As the plasma wave propagates through a non-uniform plasma channel, the plasma wave perturbation causes focusing in the part of the laser that propagates with the electron density trough and defocusing in the part moving with the crest. This yields an axial gradient in the intensity of the laser and produces a ponderomotive force on the electrons. The ponderomotive force drives the plasma wave, which in turn makes the modulational instability grow. The growth rate of the modulational instability becomes larger with the increase in non-uniformity of a shallow plasma channel. In a deep cavitated plasma channel the growth rate of the modulational instability increases with the laser pulse amplitude.</P>
New ionic polymer–metal composite actuators based on PVDF/PSSA/PVP polymer blend membrane
Panwar, Varij,Kang, Bong‐,Sik,Park, Jong‐,Oh,Park, Suk‐,Ho Wiley Subscription Services, Inc., A Wiley Company 2011 Polymer engineering and science Vol.51 No.9
<P><B>Abstract</B></P><P>Ionic polymer–metal composite (IPMC) actuators that display continuously large actuation displacements without back relaxation and with large blocking force at low direct current (DC) voltages are used as biomimetic sensors, actuators and biomedical devices. This article reports the preparation and actuation performance of new IPMC actuators based on the polyvinylidene fluoride (PVDF)/polystyrene sulfonic acid (PSSA)/polyvinyl pyrrolidone (PVP) polymer blend membrane, which requires low voltage DC. The performance results of the proposed IPMC actuators are compared with Nafion‐based IPMC actuators. In the blend membrane, PVDF is the hydrophobic polymer, PSSA is the polyelectrolyte, and PVP is the hydrophilic basic polymer. The proposed IPMC actuators based on the PVDF/PSSA/PVP blend membrane of polymer mixture ratios of 60/15/25 and 50/25/25 gave higher actuation displacement and higher blocking force at low DC voltages than the Nafion‐based IPMC actuator. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers</P>
Panwar, Varij,Park, Jong-Oh,Park, Suk-Ho,Kumar, Sanjeev,Mehra, R. M. Wiley Subscription Services, Inc., A Wiley Company 2010 Journal of applied polymer science Vol.115 No.3
<P>The conducting polymer composite material is desired to have a high dielectric constant and high dissipation factor in low and high frequency ranges, so that it can be used in charge storing devices, decoupling capacitors, and electromagnetic interference (EMI) shielding applications. Currently, on-going research is trying to enhance the dielectric constant of ceramic powder-polymer, metal powder-polymer, and nanotube-polymer composites in the low frequency region. In this article, we present the dielectric properties of polypropylene (PP)-graphite (Gr) composites in low and radio frequency ranges. Furthermore, the EMI shielding properties of these composites are examined in the radio frequency range. The PP-Gr composites were prepared by mixing and the hot compression mold technique. The electrical conductivity and dielectric constant of PP-Gr composites with graphite volume fraction follow the power law model of percolation theory. The percolation threshold of the composites is estimated to be 0.0257 (∼ 5wt % of Gr). The current of PP-Gr composites as a function of voltage shows a nearly ohmic behavior above the percolation threshold. Shore-D hardness of the composites is decreased with the addition of conducting filler. The PP-Gr composites exhibit a high dielectric constant and high dissipation factor with the addition of graphite in low frequency and radio frequency regions, so they can be used in the proposed applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010</P>
Studies on Some Bioactive 1,1-Bis(2-benzylidene-5-aryliden-1,3-thiadiazolidin-4-one)cyclopropane
Panwar, Hemant,Chaudhary, Nidhi,Singh, Sachi,Chawla, Amit Korean Chemical Society 2011 대한화학회지 Vol.55 No.6
Some novel heterocyclic derivatives of 1,1-bis(2-phenyl-5-arylidine-1,3-thiadiazolidin-4-one)cyclopropane 4(a-i) have been synthesized from cyclopropane dicarboxylic acid and substituted thiadiazole moieties. All the synthesized compounds have been characterized by elemental and spectral (I.R., $^1H$-NMR, Mass) analysis. Furthermore, above said compounds were screened for their antifungal and antibacterial activities. Compound 4c was found the most potent one which further evaluated for lesser toxicity test.