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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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Microstructure refinement and properties of 1.0C-1.5Cr steel in a duplex treatment combining double quenching and laser surface quenching
摘要： The 1.0C-1.5Cr steel was subjected to conventional quenching and laser surface quenching treatment. A process combing double quenching and laser surface quenching was proposed for enhancing surface hardness and obtaining finer microstructure. The cementite dissolution and grain growth behavior in the austenitizing process of single quenching, double quenching, and laser surface quenching were studied. The results indicated that compared with single quenching, mean diameter of undissolved cementite particles (UCP) was much finer in double quenching, and the final prior austenite grain size (PAGS) could be decreased by nearly 40% to about 4.5 μm. Both grain and cementite particles near the surface will coarsen after laser surface treatment. Compared with single quenching, the PAGS within hardened layer can be decreased by at least 11% through double quenching, and the mean diameter of UCP at the bottom of hardened layer can be decreased by about 20%. Compared with conventional quenching, surface hardness was enhanced by about 20% through laser surface quenching, contributing to the wear resistance. However, the hard and brittle surface layer tends to be crack source during the impact process, leading to the deterioration of final impact toughness. Under the identical laser parameters, the impact absorbed energy is similar in both single and double quenching, which is about 25% of that before laser surface quenching. The impact absorbed energy can be increased from 22J to 28J by preheating at 160 C during the laser surface quenching.
关键词： Impact toughness,Grain size,Cementite,Laser surface quenching,Double quenching,Wear
更新于2025-09-19 17:13:59
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Growth and characterization of ZnxSn1?xSe films for use in thin film solar cells
摘要： We have fabricated ZnxSn1?xSe (ZTSe) ?lms for the ?rst time. Samples were fabricated by chemical molecular beam deposition method at atmospheric pressure in hydrogen ?ow. ZnSe and SnSe powders with 99.999% purity were used as precursors. The temperature of precursors varied in the range of (850–950) °C. Films were deposited at substrate temperature of (500–600) °C. Borosilicate glass was used as a substrate. We have studied ZTSe ?lms by EDS, XRD and SEM. The samples had orthorhombic and cubic structures depending on composition. Results of EDS have shown that stoichiometric composition of samples moved to ZnSe side by increasing with substrate temperature. SEM pictures have shown that samples had polycrystalline structure. The grain size varied in the range of (2–15) μm. The grain size of samples increased from (2–5) μm to (15–20) μm for substrate temperatures of 500 °C and 550 °C respectively. While, at a substrate temperature of 600 °C the grain size decreased up to (3–5) μm, possibly, because of increasing of ZnSe content. XRD analysis has shown that samples have ZnSe, SnSe, Se and Sn phases. The band gap of samples varied in the range of 1.0–2.0 eV depending on the ?lm compositions. An inversion of the conductivity type was found: samples fabricated at 500 °C and 550 °C performed of p-type conductivity; while samples fabricated at 600 °C showed n-type conductivity.
关键词： Grain size,Conductivity,X-ray,ZnXSn1?XSe ?lms,Morphology
更新于2025-09-19 17:13:59
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InP-Based Quantum Dots Having an InP Core, Composition-Gradient ZnSeS Inner Shell, and ZnS Outer Shell with Sharp, Bright Emissivity and Blue Absorptivity for Display Devices
摘要： Indium phosphide (InP) has been regarded as the most promising composition of visible quantum dot (QD) emitters for the application to next-generation display devices primarily due to its environmental benignity. Bright, sharp emissivity of InP QDs should be pursued for the realization of high-efficiency, wide-color gamut display devices. Photoluminescence (PL) performance of InP QDs has been greatly improved based on synthetic advances enabling the securement of core size homogeneity and the formation of exquisite core/shell heterostructure. Till now high-quality fluorescent InP QDs have been attainable exclusively with use of a hazardous phosphorus (P) precursor of tris(trimethylsilyl)phosphine ((TMS)3P) against green chemistry. In this work we report a synthetic breakthrough of green InP QDs towards narrow, bright emissivity by using a much cheaper, safer P alternative of tris(dimethylamino)phosphine ((DMA)3P). For this, QD synthesis proceeds via so-called two-step approach, where as-grown InP cores are subjected to a stepwise size fractionation process and then placed in the consecutive double shelling of composition-gradient ZnSexS1-x inner and ZnS outer shell. The chemical composition (x) of ZnSexS1-x inner shell in the range of 0.09?0.36 is varied to explore its effects on PL quantum yield (QY), size, and blue excitation light absorptivity. Owing to the effective core size fractionation and elaborately designed heterostructure the resulting InP/ZnSexS1-x/ZnS QDs exhibit exceptional green (527 nm) PL features of a sharp line width of 37 nm and a high PL QY of 87%, which have been never achievable to date from non-(TMS)3P-based QDs, when an optimal inner shell composition is applied.
关键词： double shelling,InP QDs,PL QY,sharp line width,size fractionation,phosphorus precursor
更新于2025-09-19 17:13:59
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Control of the size and luminescence of carbon nanodots by adjusting ambient pressure in laser ablation process
摘要： A femtosecond pulse laser was used to fabricate carbon nanodots (CDs), of which the particle size and photoluminescence (PL) properties could be effectively controlled by adjusting ambient pressure. By increasing the reaction pressure, the particle size of CDs gradually decreased and finally reached less than 1 nm at 4 MPa. Simultaneously, the fluorescence intensity of the CDs first increased and then decreased by further increasing the pressure. By examining the PL dynamics and the chemical structure of the CDs, we found that the PL change of products was attributed to the quantity change of functional groups attached to the CDs due to the surface area change of the carbonic core.
关键词： laser ablation,ambient pressure,photoluminescence,particle size,carbon nanodots
更新于2025-09-19 17:13:59
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[IEEE 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Rome, Italy (2019.6.17-2019.6.20)] 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Solution-Processed Electrodes for Flexible Organic and Perovskite Solar Cells
摘要： In an acyclic multicast network, it is well known that a linear network coding solution over GF(q) exists when q is sufficiently large. In particular, for each prime power q no smaller than the number of receivers, a linear solution over GF(q) can be efficiently constructed. In this paper, we reveal that a linear solution over a given finite field does not necessarily imply the existence of a linear solution over all larger finite fields. In particular, we prove by construction that: 1) for every ω ≥ 3, there is a multicast network with source outdegree ω linearly solvable over GF(7) but not over GF(8), and another multicast network linearly solvable over GF(16) but not over GF(17); 2) there is a multicast network linearly solvable over GF(5) but not over such GF(q) that q > 5 is a Mersenne prime plus 1, which can be extremely large; 3) a multicast network linearly solvable over GF(q m1 ) and over GF(q m2 ) is not necessarily linearly solvable over GF(q m1+m2 ); and 4) there exists a class of multicast networks with a set T of receivers such that the minimum field size qmin for a linear solution over GF(qmin) is lower bounded by (cid:3)( |T |), but not every larger field than GF(qmin) suffices to yield a linear solution. The insight brought from this paper is that not only the field size but also the order of subgroups in the multiplicative group of a finite field affects the linear solvability of a multicast network.
关键词： multicast network,field size,lower bound,Linear network coding,Mersenne prime
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE International Conference on Electrical Engineering and Photonics (EExPolytech) - St. Petersburg, Russia (2019.10.17-2019.10.18)] 2019 IEEE International Conference on Electrical Engineering and Photonics (EExPolytech) - Effective Mode Volume Evolution in the He-Ne Laser
摘要： How isogenic cell populations maintain size homeostasis, i.e., a narrow distribution of cell size, is an intriguing fundamental problem. We model cell size using a stochastic hybrid system, where a cell grows exponentially in size (volume) over time and probabilistic division events are triggered at discrete-time intervals. Moreover, whenever division occurs, size is randomly partitioned among daughter cells. We first consider a scenario where a timer (cell-cycle clock) that measures the time elapsed since the last division event regulates both the cellular growth and division rates. The analysis reveals that such a timer-controlled system cannot achieve size homeostasis, in the sense that the cell-to-cell size variation grows unboundedly with time. To explore biologically meaningful mechanisms for controlling size, we consider two classes of regulation: a size-dependent growth rate and a size-dependent division rate. Our results show that these strategies can provide bounded intercellular variation in cell size and exact mathematical conditions on the form of regulation needed for size homeostasis are derived. Different known forms of size control strategies, such as the adder and the sizer, are shown to be consistent with these results. Finally, we discuss how organisms ranging from bacteria to mammalian cells have adopted different control approaches for maintaining size homeostasis.
关键词： cell size homeostasis,stochastic hybrid systems,sizer,moment dynamics,moment closure,Adder
更新于2025-09-19 17:13:59
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Beyond the Toolpath: Site-Specific Melt Pool Size Control Enables Printing of Extra-Toolpath Geometry in Laser Wire-Based Directed Energy Deposition
摘要： A variety of techniques have been utilized in metal additive manufacturing (AM) for melt pool size management, including modeling and feed-forward approaches. In a few cases, closed-loop control has been demonstrated. In this research, closed-loop melt pool size control for large-scale, laser wire-based directed energy deposition is demonstrated with a novel modification, i.e., site-specific changes to the controller setpoint were commanded at trigger points, the locations of which were generated by the projection of a secondary geometry onto the primary three-dimensional (3D) printed component geometry. The present work shows that, through this technique, it is possible to print a specific geometry that occurs beyond the actual toolpath of the print head. This is denoted as extra-toolpath geometry and is fundamentally different from other methods of generating component features in metal AM. A proof-of-principle experiment is presented in which a complex oak leaf geometry was embossed on an otherwise ordinary double-bead wall made from Ti-6Al-4V. The process is introduced and characterized primarily from a controls perspective with reports on the performance of the control system, the melt pool size response, and the resulting geometry. The implications of this capability, which extend beyond localized control of bead geometry to the potential mitigations of defects and functional grading of component properties, are discussed.
关键词： closed-loop control,lasers,metal,directed energy deposition,additive manufacturing,3D printing,titanium,site-specific,melt pool size
更新于2025-09-19 17:13:59
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A compact triplea??mode bandpass filter based on isosceles righta??angled triangular resonator
摘要： In this letter, a triple-mode bandpass filter based on isosceles right-angled triangular (RAT) resonator with three magnetic walls is proposed. To realize the triple-mode filter, the RAT resonator is perturbed by two metalized via-holes around the center. These via-holes form an LC resonant unit with the patch. Also, the via-holes make mode shifting of the TM010 Z mode while not affecting the TM110 Z mode in order to form the passband. The proposed filter is fabricated and measured. The center frequency is 5.51 GHz and the fractional bandwidth is 20%. The minimum in-band insertion loss and return loss are measured to be 1.26 dB and 20.5 dB. The measurement results show that the filter has featured both compact size and excellent in-band responses.
关键词： magnetic walls,isosceles right-angled triangular resonator,compact size,triple-mode bandpass filter
更新于2025-09-19 17:13:59
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Highly efficient mixed-halide mixed-cation perovskite solar cells based on rGO-TiO2 composite nanofibers
摘要： In this investigation, the electrospun reduced graphene oxide-titanium oxide composite nanofibers as an electron transporting materials have been employed for the perovskite solar cells. The synthesized electron transporting materials have been used for the fabrication of mixed-cation lead mixed-halide (FAPbI3)0.85(MAPbBr3)0.15 perovskite solar cells. The influence of reduced graphene oxide on titanium oxide nanofibers and their morphological and electronic properties have been investigated in detail. The optimized device having FTO/Bl-TiO2/rGO4–TiO2/(FAPbI3)0.85(MAPbBr3)0.15/spiro-MeOTAD/Au configuration exhibited 17.66 % power conversion efficiency with an open circuit voltage of 1.070 V, short circuit current density of 22.16 mAcm-2 and fill factor of 0.754. This obtained efficiency is much higher than that of mesoporous- titanium oxide (14.39 %), pristine- titanium oxide nanofibers (15.82 %) and other reduced graphene oxide- titanium oxide composite nanofibers based electron transporting materials.
关键词： electron transporting materials,large grain size,high-efficiency,Perovskite solar cells,role of rGO in TiO2 nanofibers
更新于2025-09-19 17:13:59
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Size-controlled synthesis of gold nanoparticles by ultrafine bubbles and pulsed ultrasound
摘要： Size-controlled gold nanoparticles (AuNPs) were synthesized by ultrasonic irradiation of HAuCl4 aqueous solutions with the aid of ultrafine bubbles (UFBs) in the absence of any capping and reducing agents. Upon addition of air-UFBs, the mean diameter of the spherical AuNPs decreased. This result was attributed to the sonochemical reduction of gold ions in aqueous solution being accelerated by the UFBs. Moreover, the AuNPs were stable in a solution containing UFBs because AuNPs electrostatically adsorbed onto UFBs, whose lifetime in water was very long. Compared with the mean diameter of AuNPs synthesized with argon-, nitrogen- and oxygen-UFBs, that of AuNPs synthesized with air-UFBs was smaller. Pulsed ultrasound delivered with the same time-averaged power as continuous-wave irradiation further decreased the mean diameter of the AuNPs. Size-controlled synthesis of AuNPs without the use of a capping or reducing agent was successful through optimization of the number air-UFBs and the pulsed ultrasound conditions.
关键词： Gold nanoparticles,Size control,Ultrasound,Pulse wave,Ultrafine bubbles,Colloidal stabilization
更新于2025-09-19 17:13:59