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- 2018
- Solar Photovoltaic (SPV)
- Fuzzy Logic Control (FLC)
- MATLAB/Simulink
- Simulation
- Variable Step Size Incremental Conductance (VSS InC)
- Maximum Power Point Tracking (MPPT)
- Electrical Engineering and Automation
- Cochin University College of Engineering
- T.K.M College of Engineering
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Comparative research on two surface conductivity models for the scattering of electromagnetic wave by the charged sphere
摘要： The surface conductivity model plays an important role in solving the electromagnetic scattering of microwave by the charged particle. We compared two models that can be used in the scattering of electromagnetic wave by the charged spherical particle. The results show that the extinction efficiency and the scattering efficiency calculated through these two models are much different in some cases, and which also affect by the particle size, refractive index, and its charged quantity. However, when the size parameter of particle is larger enough, the results from these two models became consistent with each other.
关键词： Charged spheres,Surface conductivity,Size parameters,Mie scattering,Scattering and extinction
更新于2025-09-23 15:23:52
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A novel approach for in-situ soot size distribution measurement based on spectrally resolved light scattering
摘要： The present study demonstrates the exploitation of the spectral elastic light scattering technique. Additional information provided by the spectral response of the light scattering signals enables the measurement of the soot size distribution with only two scattering angles. It also provides quantitative data on the spectral dependence of the soot optical index, which is related to the soot chemical composition. The measurement principle consists in dividing the scattered spectra collected at two scattering angles and processing this ratio using the Rayleigh–Debye–Gans theory for Fractal Aggregates (RDG-FA). It is shown that the median diameter of gyration and geometric standard deviation of a lognormal soot size distribution can be determined without any prior information on key parameters such as the fractal prefactor, particle primary diameter, aggregate number density and soot optical properties. A proof of concept was performed on soot particles produced by a miniCAST generator by comparing the optical results with the soot size distributions measured by SMPS. A statistical Bayesian inversion approach was used to determine posterior distributions with a particular emphasis on their uncertainty quantification.
关键词： Light scattering,Bayesian,Spectral scattering,Optical properties,Soot,Size distribution
更新于2025-09-23 15:23:52
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Preparation of graphene oxide with large lateral size and graphene/polyimide hybrid film via in situ “molecular welding” strategy
摘要： In this letter, we report an "ultrasonication-free" direct exfoliation method to obtain graphene oxide with large lateral size (LGO). The average size of LGO sheets is about 50 lm * 50 lm. The g-LGO film shows a superior in-plane thermal conductivity after the graphitization treatment. Furthermore, the in situ "molecular welding", using polyimide (PI) to weld up the GO sheets, is conducted to improve the performance of hybrid thermal conducting film. The thermal conductivity of g-LGO/PI film is 1053.975 ± 8.762 W m-1 K-1, superior to that of the g-LGO film and g-SGO/PI. The direct preparation method to obtain GO with large lateral size, followed by such an in situ "molecular welding" strategy by PI, provides a promising way to fabricate graphene-based film for efficient thermal management.
关键词： Molecular welding,In situ polymerization,Large lateral size,Thermal properties,Carbon material
更新于2025-09-23 15:23:52
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Inverse size-dependence of piezoelectricity in single BaTiO3 nanoparticles
摘要： The piezoelectric charge coefficients d33 of single BaTiO3 (BT) nanoparticles (NPs) were characterized using a transmission electron microscope (TEM) that is equipped with a precise charge meter and an in-situ TEM indentation holder that enables controlled compression experiments. An exceptionally high d33 of 1775 pC/N was obtained in NPs that are smaller than the critical diameter (D; typically known as < 100 nm) that has been regarded as the lower limit to permit for ferroelectricity in BT. The mechanical conversion efficiency of piezoelectric BT nanogenerators enhanced as D of BT NPs was decreased; this result corresponds with the single-NP compression measurements of d33. This quantification of the effect of D in ferroelectric materials may guide development of efficient and high-powered nanostructured piezoelectric energy devices such as piezoelectric nanogenerators.
关键词： in-situ TEM,size effect,STEM,Ferroelectric,piezoelectric,nanogenerator
更新于2025-09-23 15:23:52
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Compact Dual-Channel Balanced Filter and Balun Filter Based on Quad-Mode Dielectric Resonator
摘要： In this paper, we propose a method for designing a dual-channel balanced filter and a dual-channel balun filter based on the quad-mode dielectric resonator (DR) for the first time. By sharing one common quad-mode DR, two balanced filters or two balun filters are integrated as one single-cavity configuration, featuring compact size and high integration. A cylindrical DR with two short ends is investigated to construct the quad-mode DR. By properly arranging input and output feeding probes, two modes of the DR are only excited by the feeding probes of one channel and the other two modes are excited by that of the other channel. Accordingly, signals cannot be transmitted between the two channels, resulting in high isolation. Moreover, the required out-of-phase characteristics of the balanced and balun filters can be obtained by the inherent electromagnetic field properties of the DR without adding additional circuits, featuring a simple structure. For demonstration, a dual-channel balanced filter and a dual-channel balun filter are designed and fabricated, showing excellent balanced or balun filter performance of each channel as well as high isolation between the two channels. As compared to the other reported DR balanced and balun filters, the proposed designs exhibit a significant size reduction, which are attractive in wireless systems.
关键词： Balanced filter,high Q factor,dielectric resonator (DR),balun filter,MIMO,size reduction,dual-channel
更新于2025-09-23 15:23:52
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One-drop Self-assembly and Size Control of Organic Nonlinear Optical Crystal DSNS Nanowires
摘要： In this study, we demonstrate a one-drop self-assembly method for fabricating nanowires (NWs) of organic second-order nonlinear optical (NLO) material, 4-N, N-dimethylamino-4'-N'-methyl- stilbazolium 2-naphthalenesulfonate (DSNS). By controlling the parameters of the self-assembly process, we successfully controlled the length of DSNS from a few micrometers to millimeters. The obtained NWs have very high surface quality with surface roughness <150 pm, which is highly beneficial for fabricating integrated optical devices. DSNS NW has the same triclinic crystal structure as that of bulk crystal and exhibits excellent second-order NLO and fluorescent properties, which could provide wide opportunities for on-chip optoelectronic devices and integrated photonic systems. Furthermore, the one-drop self-assembly method only requires reagents in microgram quantities, and thus this method is extremely environment-friendly.
关键词： one-drop self-assembly,organic nanowire,size control,nonlinear optical material
更新于2025-09-23 15:23:52
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Quantitative Measure of the Size Dispersity in Ultrasmall Fluorescent Organic-Inorganic Hybrid Core-Shell Silica Nanoparticles by Small-angle X-ray Scattering
摘要： Small-angle X-ray scattering (SAXS) was performed on dispersions of ultrasmall (d < 10 nm) fluorescent organic-inorganic hybrid core-shell silica nanoparticles synthesized in aqueous solutions (C′ dots) by using an oscillating flow cell to overcome beam induced particle degradation. Form factor analysis and fitting was used to determine the size and size dispersity of the internal silica core containing covalently encapsulated fluorophores. The structure of the organic poly(ethylene glycol) (PEG) shell was modelled as a monodisperse corona containing concentrated and semi-dilute regimes of decaying density and as a simple polydisperse shell to determine the bounds of dispersity in the overall hybrid particle. C′ dots containing single growth step silica cores have dispersities of 0.19-0.21; growth of additional silica shells onto the core produces a thin, dense silica layer, and increases the dispersity to 0.22-0.23. Comparison to FCS and DLS measures of size shows good agreement with SAXS measured and modelled sizes and size dispersities. Finally, comparison of a set of same sized and purified particles demonstrates that SAXS is sensitive to the skewness of the gel permeation chromatography elugrams of the original as-made materials. These and other insights provided by quantitative SAXS assessments may become useful for generation of robust nanoparticle design criteria necessary for their successful and safe use, for example in nanomedicine and oncology applications.
关键词： nanomedicine,size dispersity,core-shell nanoparticles,silica nanoparticles,Small-angle X-ray scattering,PEGylation
更新于2025-09-23 15:23:52
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Multispectral optoacoustic tomography (MSOT) for imaging the particle size-dependent intratumoral distribution of polymeric micelles
摘要： Purpose: This study proposes the utilization of multispectral optoacoustic tomography (MSOT) to investigate the intratumoral distribution of polymeric micelles and effect of size on the biodistribution and antitumor efficacy (ATE). Materials and methods: Docetaxel and/or optoacoustic agent-loaded polymeric micelles (with diameters of 22, 48, and 124 nm) were prepared using amphiphilic block copolymers poly (ethylene glycol) methyl ether-block-poly (D,L lactide) (PEG2000–PDLLAx). Subcutaneous 4T1 tumor-bearing mice were monitored with MSOT imaging and IVIS? Spectrum in vivo live imaging after tail vein injection of micelles. The in vivo results and ex vivo confocal imaging results were then compared. Next, ATE of the three micelles was found and compared. Results: We found that MSOT imaging offers spatiotemporal and quantitative information on intratumoral distribution of micelles in living animals. All the polymeric micelles rapidly extravasated into tumor site after intravenous injection, but only the 22-nm micelle preferred to distribute into the inner tumor tissues, leading to a superior ATE than that of 48- and 124-nm micelles. Conclusion: This study demonstrated that MSOT is theranostically a powerful imaging modality, offering quantitative information on size-dependent spatiotemporal distribution patterns after the extravasation of nanomedicine from tumor blood vessels.
关键词： intratumoral distribution,MSOT,multispectral optoacoustic tomography,in vivo imaging,tumor model,particle size,polymeric micelle
更新于2025-09-23 15:23:52
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Néel transition in the multiferroic BiFeO <sub/>3</sub> -0.25PbTiO <sub/>3</sub> nanoparticles with anomalous size effect
摘要： The role of size reduction on the structural parameters, antiferromagnetic transition temperature (TN), and spin reorientation transition temperature of BiFeO3-0.25PbTiO3 (BF-0.25PT) has been studied. Rietveld analysis using high resolution synchrotron x-ray powder diffraction data confirms that the space group of BF-0.25PT solid solutions is monoclinic Cc and not rhombohedral R3c for both bulk and nanocrystalline powders. This settles a longstanding controversy about the structure of these solid solutions toward the BiFeO3 rich end of the morphotropic phase boundary in the BiFeO3-xPbTiO3 system. Using magnetization and neutron powder diffraction data, we show that the Néel transition temperature (TN) of BF-0.25PT increases from 445 K for bulk to 480 K for 150 nm particle size. This is in marked contrast to the scaling theories of phase transitions in finite size systems. We also show that the spin reorientation transition occurring below TN in bulk monoclinic compositions like BF-0.25PT is suppressed in the nanocrystalline samples of ～150 nm particle size. Based on Rietveld refined structural parameters, we show that the asymmetry and non-linearity of the Fe-O-Fe superexchange pathways grow with decreasing particle size and that they exhibit a strong correlation with TN. We believe that the substantially enhanced Dzyaloshinskii-Moriya interaction with decreasing particle size as a result of asymmetric and non-collinear Fe-O-Fe superexchange pathways may be the key factor in raising the TN on decreasing the particle size. These observations present a new facet of type-I multiferroic materials, where superexchange pathways are intimately dependent on the ferroelectric distortion.
关键词： multiferroic,antiferromagnetic transition,BiFeO3-PbTiO3,size effect,Dzyaloshinskii-Moriya interaction,Néel transition,nanoparticles
更新于2025-09-23 15:23:52
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Derivation of space-resolved normal joint spacing and in situ block size distribution data from terrestrial LIDAR point clouds in a rugged Alpine relief (Kühtai, Austria)
摘要： Terrestrial laserscan (TLS) surveys allow the geological investigation of rock slopes, which cannot be measured by direct surveys because of inaccessibility, high hazard potential or excessive effort. The normal joint spacing and the in situ block size distribution are relevant properties for rock mass characterisation but are commonly evaluated statistically or at small regions only. This study presents the jointing characterisation of an Alpine rock slope by both scanline data and a new, automated analysis of point cloud data. The slope, located in the L?ngental (Austria), is characterised by a rugged Alpine relief and granodioritic gneisses fractured by non-persistent joints. The scanline data and the TLS surveys were used to investigate joint set orientations, normal joint spacings and in situ block sizes. Area-wide maps of rock slope properties were prepared from the results of the point cloud analysis. The general results derived from the point clouds are in good agreement with the scanline data. The space-resolved maps show larger block sizes in some of the higher ranging sub-regions and small block sizes in tectonically formed gullies, as well as various local variations. These visualisations are much more beneficial for most rock mechanical questions than common statistical data evaluation approaches using pre-defined sub-regions, which are treated as homogenous areas and thus are missing space-resolved information.
关键词： Point cloud analysis,Terrestrial laserscan,Normal joint spacing,Austria,In situ block size distribution,Joint characterisation
更新于2025-09-23 15:23:52