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- 2019
- low-temperature electronics
- class AB operation
- optimization of analog electronic circuit
- operational amplifier
- LTspice environment
- buffer amplifier
- junction field-effect transistors
- Electronic Science and Technology
- Don State Technical University
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Minimizing Defect States in Lead Halide Perovskite Solar Cell Materials
摘要： In order to reach the theoretical e?ciency limits of lead-based metal halide perovskite solar cells, the voltage should be enhanced because it su?ers from non-radiative recombination. Perovskite materials contain intrinsic defects that can act as Shockley–Read–Hall recombination centers. Several experimental and computational studies have characterized such defect states within the band gap. We give a systematic overview of compositional engineering by distinguishing the di?erent defect-reducing mechanisms. Doping e?ects are divided into in?uences on: (1) crystallization; (2) lattice properties. Incorporation of dopant in?uences the lattice properties by: (a) lattice strain relaxation; (b) chemical bonding enhancement; (c) band gap tuning. The intrinsic lattice strain in undoped perovskite was shown to induce vacancy formation. The incorporation of smaller ions, such as Cl, F and Cd, increases the energy for vacancy formation. Zn doping is reported to induce strain relaxation but also to enhance the chemical bonding. The combination of computational studies using (DFT) calculations quantifying and qualifying the defect-reducing propensities of di?erent dopants with experimental studies is essential for a deeper understanding and unraveling insights, such as the dynamics of iodine vacancies and the photochemistry of the iodine interstitials, and can eventually lead to a more rational approach in the search for optimal photovoltaic materials.
关键词： semiconductor,solar energy,photovoltaics,doping,thin ?lm materials,voltage loss,stabilization,optimization,charge generation,light harvesting
更新于2025-09-23 15:21:01
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Extraction of uncertain parameters of a single-diode model for a photovoltaic panel using lightning attachment procedure optimization
摘要： The aim of this work is to improve the estimation of parameters of solar photovoltaic models. An approach based on lightning attachment procedure optimization, which takes into account the uncertainties of measurements, is proposed. The approach includes three steps: the extraction of the parameters in a conventional manner, the determination of the partial uncertainties of all the parameters, and finally the determination of the instantaneous parameters based on the results of the first two steps. To validate the proposed theoretical developments, the approach is applied to four different photovoltaic parameter estimation problems. The results obtained are compared with those given by well-established algorithms to confirm the effectiveness of the proposed method, revealing that the proposed method exhibits very effective performance with a root-mean-square error on the order of 1 × 10?17, compared with 1 × 10?4 for existing literature methods.
关键词： Lightning attachment procedure optimization,Photovoltaic modeling,Parameter estimation,Uncertain measurements
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Citizens on the driving seat of Photovoltaics
摘要： Reliable data congestion analytics in crowdsourced eHealth networks becomes particularly important, especially in big data era, because of wide adaption of ubiquitous crowdsourced healthcare participants. Since a crowdsourced eHealth network has intermittent connectivity to its remote healthcare provider, researchers usually use some well-studied networks to model the novel network, but data congestion analytics is still a big problem in most intermittent connecting networks. In most cases, data congestion analytics may be realized by ?xing the number of forwarded copies, but sometimes, it cannot suit the changing network environments well. This problem could be solved by modifying packet forwarding conditions dynamically through detecting real-time network environment. Based on this idea, in this paper, an optimized routing algorithm named RSW (reduced variable neighborhood search-based spray and wait) is proposed. In the algorithm, nodes will exchange and store each other’s buffer status during their communication, based on which, current network environments will be evaluated and quanti?ed as a real-time threshold. Then, spray and wait adapts the threshold for data congestion control. Simulation shows that the proposed algorithm increases data packet delivery probability, and optimize the overhead ratio dramatically, which can be up to ten times lower than that of standard algorithm.
关键词： congestion control,optimization,Data analytics,crowdsourced eHealth networks
更新于2025-09-23 15:21:01
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[IEEE 2019 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Guangzhou, China (2019.5.19-2019.5.22)] 2019 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Compact Cross-coupled Quarter-mode SIW Bandpass Filters with Different Locations of Input and Output Ports
摘要： We propose an effective approach for optimal wideband cloaking of objects with arbitrary shapes exploiting adjoint sensitivity analysis. Our method optimizes the voxel-by-voxel constitutive parameters of an anisotropic cloak resulting in a large number of optimizable parameters. The associated sensitivities of a wideband cloaking objective function are efficiently estimated using our in-house anisotropic adjoint variable method (AVM) simulator. Only one adjoint simulation is needed regardless of the number of required sensitivities. A gradient-based optimization algorithm utilizes the available sensitivity information to iteratively improve the wideband cloaking objective function and to determine the constitutive parameters of the optimal cloak.
关键词： optimization,transmission line matrix (TLM) method,cloaking,Adjoint variable method (AVM)
更新于2025-09-23 15:21:01
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Optimization of Temperature Dependence of Heteronanolaser Threshold Current with Account for the Thickness and Dielectric Properties of the Heterostructure Waveguide Nano-Layer Material
摘要： An exact problem of the electromagnetic wave propagation in a multilayer heteronanostructure with complex values of the dielectric constant (permittivity) is solved. The contribution to the refractive index of an additive to the dielectric constant due to the injected carriers is taken into account. A heterostructure based on a nanosystem used for the manufacture of lasers in the range 0.94–1.14 μm is considered. The methods and approaches used are also applicable for optimizing multilayer structures based on other solid solutions and those with several quantum wells. Based on the calculations of the temperature dependence of the radiation characteristics of injection lasers based on heteronanostructures, it was shown that the anomalous behavior of the temperature dependence of the threshold current is associated with a weakening of the waveguide properties of their active region. In accordance with the calculation results, the heteronanotructures parameters of injection lasers were optimized with respect to the thickness and dielectric properties of the waveguide nanolayer material, which made it possible to significantly reduce the temperature dependence of their radiative characteristics.
关键词： solid solution,threshold current,optimization of the heterostructure parameters,local gain,mode gain,injection lasers,optical waveguide,heteronanostructure,quantum-well heterostructures
更新于2025-09-23 15:21:01
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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) - Design and Implementation of Fiber-embedded Plasmonic Structures in Microwires
摘要： General principles are developed using a finite element model regarding how time-dependent power dissipation of magnetic nanoparticles can be used to optimize hyperthermia selectivity. To make the simulation more realistic, the finite size and spatial location of each individual nanoparticle is taken into consideration. When energy input into the system and duration of treatment is held constant, increasing the maximum power dissipation of nanoparticles increases concentrations of energy in the tumor. Furthermore, when the power dissipation of magnetic nanoparticles rises linearly, the temperature gradient on the edge of the tumor increases exponentially. With energy input held constant, the location and duration of maximum power dissipation in the treatment time scheme will affect the final energy concentration inside the tumor. Finally, connections are made between the simulation results and optimization of the design of nanoparticle power dissipation time-schemes for hyperthermia.
关键词： treatment planning,finite-element modeling,Hyperthermia optimization,magnetic nanoparticles
更新于2025-09-23 15:21:01
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Topology Optimization-Based Inverse Design of Plasmonic Nanodimer with Maximum Near-Field Enhancement
摘要： The near-field enhancement factor is one of the most significant parameters to evaluate the performance of plasmonic nanostructures. Numerous efforts have been made to maximize the enhancement factor through optimizing the size, shape, and spatial arrangement of metallic nanostructures with simple geometries, such as disk, triangle, and rod. This work implements topology optimization to inversely design a metallic nanoparticle dimer with the goal of optimizing the near-field enhancement factor in its sub-10 nm gap. By optimizing the material layout within a given design space, the topology optimization algorithm results in a plasmonic nanodimer of two heart-shaped particles having both convex and concave features. Full-wave electromagnetic analysis reveals that the largest near-field enhancement in the heart-shaped nanoparticle dimer is originated from the greatest concentration of surface charges at the nano-heart apex. Inversely designed heart-, bowtie-, and disk-shaped nanodimers are fabricated by using focused helium ion beam milling with a “sketch and peel” strategy, and their near-field enhancement performances are characterized with nonlinear optical spectroscopies at the single-particle level. Indeed, the heart-shaped nanodimer exhibits much stronger signal intensities than the other two structures. The present work corroborates the validity and effectiveness of topology optimization-based inverse design in achieving desired plasmonic functionalities.
关键词： topology optimization,near-field enhancement,plasmonic nanostructures,inverse design,nonlinear optics
更新于2025-09-23 15:21:01
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Designing photonic materials with complete band gaps by topology optimization
摘要： Photonic materials may exhibit the propagation of electromagnetic waves is totally prohibited. To achieve a complete photonic band gap (CPBG) for transverse magnetic (TM) and transverse electric (TE) modes, the bi-directional evolutionary structure optimization (BESO) method originated from structural design is extended for this purpose. The optimization problem is formulated with maximizing the minimum imaginary part of complex wave vectors for TM and TE modes. According to sensitivity analysis, the material distribution within the primitive unit cell of photonic materials is adjusted step by step so as to enlarge the minimum imaginary part of wave vectors. In doing so, the CPBG at the specific frequency is obtained at the desired frequency, and the optimized structures of photonic materials with novel topological patterns are achieved. Numerical examples demonstrate that the effectiveness of the proposed topology optimization method for opening the CPBGs at various specified frequencies, which is of significance in controlling the propagation of electromagnetic waves of any polarization.
关键词： Topology optimization,Complete band gap,Evanescent waves,Photonic materials
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE Electrical Power and Energy Conference (EPEC) - Montreal, QC, Canada (2019.10.16-2019.10.18)] 2019 IEEE Electrical Power and Energy Conference (EPEC) - Photovoltaic Array Reconfiguration to Reduce Partial Shading Losses using Water Cycle Algorithm
摘要： Partial Shading (PS) increases the power losses in Photovoltaic (PV) arrays significantly. Consequently, PS is considered one of the biggest challenges that face the operation of PV systems. PV arrays dynamic reconfiguration is a promising technique used to reduce PS losses. This paper proposes the Water Cycle Algorithm (WCA) as a new optimization technique for large PV array reconfiguration to reduce PS power losses. The execution time of the proposed algorithm is shorter than the existing algorithms when dealing with large PV arrays under irregular partial shading patterns.
关键词： photovoltaic,partial shading,reconfiguration,water cycle algorithm,optimization
更新于2025-09-23 15:21:01
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<i>(Invited) The Scaling-Down and Performance Optimization of InAs Nanowire Field Effect Transistors</i>
摘要： Due to their fascinating properties, InAs nanowires have drawn great attention for the channel material in future transistors. Scaling-down has been an effective way to improve the performance of transistors continuously for decades. Here, we review our recent progresses on InAs nanowire field effect transistors (FETs) when they are scaled down. Our group investigates the electrical characteristics of InAs nanowire thinner than 10 nm. Both the size-effect and the contact properties of ultrathin nanowires are explored. Moreover, the effects of InAs crystal phase and orientation are studied for further optimizing the device performance. In addition, FETs with partial gate are studied to suppress the BTBT-induced off-current. Furthermore, to improve the electrostatics control of the gate, our group develops a method to fabricate vertical GAA FETs with all-metal electrodes based on self-catalyzed grown InAs nanowire arrays.
关键词： orientation,crystal phase,performance optimization,field effect transistors,partial gate,vertical GAA FETs,InAs nanowires,scaling-down
更新于2025-09-23 15:21:01