- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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[IEEE 2019 IEEE International WIE Conference on Electrical and Computer Engineering (WIECON-ECE) - Bangalore, India (2019.11.15-2019.11.16)] 2019 IEEE International WIE Conference on Electrical and Computer Engineering (WIECON-ECE) - Closed-Loop Control of a DC-DC Four-Phase Interleaved Quadrupler for Solar Photovoltaic Applications
摘要： We propose ?lter banks in the graph spectral domain, where each ?lter is de?ned by a sum of sinusoidal waves. The main advantages of these ?lter banks are that (a) they have low approximation errors even if a lower-order shifted Chebyshev polynomial approximation is used, (b) the upper bound of the error after the pth order Chebyshev polynomial approximation can be calculated rigorously without complex calculations, and (c) their parameters can be ef?ciently obtained from any real-valued linear phase ?nite impulse response ?lter banks in regular signal processing. The proposed ?lter bank has the same ?lter characteristics as the corresponding classical ?lter bank in the frequency domain and inherits the original properties, such as tight frame and no DC leakage. Furthermore, their approximation orders can be determined from the desired approximation accuracy. The effectiveness of our approach is evaluated by comparing them with existing spectral graph wavelets and ?lter banks.
关键词： spectral graph wavelet,spectral graph ?lter bank,Graph signal processing,Chebyshev polynomial approximation
更新于2025-09-23 15:19:57
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Impact of dielectric environment on the linear and nonlinear optical properties for CdS/ZnS cylindrical core/shell quantum dots
摘要： By the mean of the effective mass approximation (E.M.A) and compact density matrix method, the energy eigenvalues, linear and nonlinear dielectric function have been theoretically investigated for CdS/ZnS cylindrical core/shell quantum dot embedded in PVA, PMMA and SiO2 matrices. Simulation results showed that the presence of the dielectric mismatch in the QD-matrix system can lead to a significant enhancement of the nonlinear dielectric function. According to our calculations, peaks of the real and imaginary part of the dielectric function can experience a redshift or a blue shift with the appropriate dielectric environment.
关键词： complex dielectric function,Effective mass approximation,cylindrical core/shell quantum dot,density matrix approach
更新于2025-09-23 15:19:57
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Dependence of direct and rescattered photoelectron spectra of fluorine anions on orbital symmetry in a short laser pulse
摘要： We theoretically investigate the photoelectron spectra of ?uorine anions by a few-cycle linearly polarized laser pulse for different atomic orbitals, which are calculated by an exact solution to the time-dependent Schr?dinger equation and by the strong-?eld approximation, respectively. Through the comparison of results by both methods, we show that the initial orbital symmetry strongly affects the main shape of the photoelectron spectra. Based on the saddle-point method, we ?nd that the orbital symmetry only affects the intracycle interference for the low-energy electron spectra. More importantly, it is found that the elastic scattering differential cross section leaves different ?ngerprints in the photoelectron spectra for atomic orbitals with different magnetic quantum numbers.
关键词： ?uorine anions,laser pulse,photoelectron spectra,elastic scattering differential cross section,time-dependent Schr?dinger equation,orbital symmetry,strong-?eld approximation,saddle-point method
更新于2025-09-23 15:19:57
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Electrically controlled dielectric band gap engineering in a two-dimensional semiconductor
摘要： The emergent class of atomically thin two-dimensional (2D) materials has opened up completely new opportunities for manipulating electronic quantum states at the nanoscale. Here we explore the concept of dielectric band gap engineering, i.e., the controlled manipulation of the band gap of a semiconductor via its dielectric environment. Using first-principles calculations based on the GW self-energy approximation we show that the band gap of a two-dimensional (2D) semiconductor, such as the transition metal dichalcogenides, can be tuned over several hundreds of meV by varying the doping concentration in a nearby graphene sheet. Importantly, these significant band gap renormalizations are achieved via nonlocal Coulomb interactions and do not affect the structural or electronic integrity of the 2D semiconductor. We investigate various heterostructure designs, and show that, depending on the size of the intrinsic dielectric function of the 2D semiconductor, the band gap can be tuned by up to 1 eV for graphene carrier concentrations reachable by electrostatic doping. Our work provides opportunities for electrically controllable band gap engineering in 2D semiconductors.
关键词： GW self-energy approximation,transition metal dichalcogenides,graphene,two-dimensional semiconductor,dielectric band gap engineering
更新于2025-09-23 15:19:57
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[IEEE IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium - Yokohama, Japan (2019.7.28-2019.8.2)] IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium - Results of Vibrational and Thermal Test for MOLI Laser Transmitter
摘要： Currently, self-healing is one of the most important functions in the smart grid. Meanwhile, fault detection, isolation, and restoration of feeder automation systems dominate the self-healing function in power distribution systems. The steps of the aforementioned function depend on the fault ?ag status of the feeder terminal unit. The conditions for setting this ?ag are judged by the feeder terminal unit overcurrent detecting curve. This paper found an ef?cient approach to calculate this curve via a half-interval method. Versatile application software with the curve plotting capability was also developed and deployed on the web server of the information-management department of Taiwan Power Company and is running successfully.
关键词： piecewise linear approximation,power distribution protection,IEEE standards,fault currents,Computer aided analysis
更新于2025-09-23 15:19:57
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Photoelectric process in GaAs quantum dot
摘要： We study the photoelectric process in single electron charged spherical GaAs/Ga1-yAlyAs quantum dot. The effective mass approximation is used with the finite potential at the dot matrix interface including the effect of self-energy. The total cross section of photoelectric process is investigated with the variation of incident photon energy and the molar concentration y of Al in Ga1-yAlyAs matrix material.
关键词： Quantum dot,Effective mass approximation,Finite potential,Photoelectric process
更新于2025-09-23 15:19:57
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Correlation between Near-Field Enhancement and Dephasing Time in Plasmonic Dimers
摘要： Near-field enhancement and dephasing time play critical roles in several applications of localized surface plasmon resonance. Here, using an example gold dimer system, we reveal the correlation between the near-field enhancement and dephasing time via time-resolved photoemission electron microscopy. Compared with isolated particles, dimers with small gap sizes show stronger near-field enhancement and shorter dephasing times. These results are well reproduced by numerical simulations and further explained by a coupled dipole approximation model. The roles of near- and far-field coupling and plasmon localization in balancing near-field enhancement and dephasing time are also unveiled.
关键词： dephasing time,time-resolved photoemission electron microscopy,near-field enhancement,plasmonic dimers,coupled dipole approximation model
更新于2025-09-23 15:19:57
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Polarization Sensitivity of Silicon Integrated Optical Antenna for Laser Communication on Small Satellite
摘要： In this paper, we consider the down-link dynamic resource allocation in multi-cell virtualized wireless networks (VWNs) to support the users of different service providers (slices) within a specific region by a set of base stations (BSs) through orthogonal frequency division multiple access (OFDMA). In particular, we develop a joint BS assignment, sub-carrier, and power allocation algorithm to maximize the network sum rate, while satisfying the minimum required rate of each slice. Under the assumption that each user at each transmission instance can connect to no more than one BS, we introduce the user-association factor to represent the joint sub-carrier and BS assignment as the optimization variable vector in the problem formulation. Sub-carrier reuse is allowed in different cells, but not within one cell. As the proposed optimization problem is inherently non-convex and NP-hard, by applying the successive convex approximation (SCA) and complementary geometric programming (CGP), we develop an efficient two-step iterative approach with low computational complexity to solve the proposed problem. For a given problem, Step 1 derives the optimum user-association and subsequently, and for an obtained user-association, Step 2 finds the optimum power allocation. Simulation results demonstrate that the proposed iterative algorithm outperforms the traditional approach in which each user is assigned to the BS with the largest average value of signal strength, and then, joint sub-carrier and power allocation is obtained for the assigned users of each cell. Simulation results reveal a coverage improvement, offered by the proposed approach, of 57% and 71% for uniform and non-uniform users distribution, respectively, leading to higher spectrum efficiency for VWN.
关键词： Complementary geometric programming,virtualized wireless networks,joint user association and resource allocation,successive convex approximation
更新于2025-09-23 15:19:57
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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) - Autonomous Path Planning by Unmanned Aerial Vehicle (UAV) for Precise Monitoring of Large-Scale PV plants
摘要： This paper presents a 3.6 GHz low-noise fractional-N digital phase-locked loop (PLL) that achieves low in-band phase noise. Phase detection is carried out by a proposed 10-bit, 0.8 ps resolution time-to-digital converter (TDC) using a charge pump and a successive-approximation-register analog-to-digital converter (SAR-ADC) with low power and small area. The latency of the TDC is addressed by the designed building blocks. The fractional spurs are reduced by dual-loop least-mean-square (LMS) calibration. A (cid:2)(cid:3)-less and MOS varactor-less LC digitally-controlled oscillator (DCO) is proposed whose frequency resolution is enhanced to 7 kHz (or a unit variable capacitance of 2.6 aF) using a bridging capacitor technique. A prototype chip is fabricated using a 65 nm CMOS process, occupying an active area of 0.38 mm2 and consuming a power of 9.7 mW at a reference frequency of 50 MHz. The measured in-band phase noise is 107.8 dBc/Hz to 110.0 dBc/Hz with a loop bandwidth of 1 to 5 MHz.
关键词： digitally controlled oscillator (DCO),least-mean-square (LMS),digital phase-locked-loop (PLL),time-to-digital converter (TDC),successive-approximation-register analog-to-digital converter (SAR-ADC),frequency synthesizer,CMOS,sub-picosecond resolution
更新于2025-09-23 15:19:57
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Searching the crystal structure of silicon using the generalized scaled hypersphere search method with the rapid nuclear motion approximation
摘要： The scaled hypersphere search method with the rapid nuclear motion approximation was applied for the prediction of the crystal structure of silicon. Five well-known structures and one novel structure were found. The space group of the novel structure found is Imma. By comparing this with the two known silicon structures in the same space group, it is found that one of these well-known Imma structures and the novel Imma structure are similar. According to our ab initio calculations based on the projector augmented wave method with the Perdew–Burke–Ernzerhof functional, the novel structure is a semiconductor, with calculated band gap 0.89 eV.
关键词： scaled hypersphere search method,crystal structure prediction,silicon,semiconductor,rapid nuclear motion approximation
更新于2025-09-23 15:19:57