- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Phononic Casimir corrections for Graphene resonator
摘要： By calculating a Casimir energy for the acoustic phonons of Graphene, we find some temperature-dependent corrections for the pretension of a Graphene sheet suspended on a trench. We obtain values of the order of few mN/m for these corrections in fully as well as doubly clamped Graphene on a narrow trench with one nanometer width, at room temperature. These values are considerable compared to the experimental values, and can increase the fundamental resonance frequency of the Graphene. The values of these corrections increase by increasing the temperature, and so they can be utilized for tuning the Graphene pretension.
关键词： Resonance frequency,Graphene sheet,Casimir energy,Acoustic phonons,Pretension,Nanoelectromechanical systems
更新于2025-09-23 15:23:52
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Ultra high transmission capacity based on optical first order soliton propagation systems
摘要： This study presents the first order optical soliton propagation systems for ultra-high transmission distance that reaches up to 20,000 Km with transmission data rates of 80 Gb/s and its corresponding maximum Q-factor and Soliton peak power. The simulation has been performed for the distance up to 20000 Km at the operating wavelength of 1300 and 1550 nm.
关键词： High data rates,Soliton propagation systems,First order soliton
更新于2025-09-23 15:23:52
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SNR analysis and estimation for efficient phase noise mitigation in millimetre-wave SC-FDE systems
摘要： This study demonstrates a signal-to-noise ratio (SNR) analysis and estimation algorithm for efficient phase noise mitigation that can be practically applied to single-carrier frequency-domain-equalisation (SC-FDE) systems that operate in millimetre-wave bands. First, the effect of phase noise in SC-FDE systems is investigated on each of the packet reception processes, namely, channel estimation, SNR estimation, and data-field reception. According to the analysis, an SNR estimation algorithm is proposed. The performance of minimum-mean-square-error equalisation and conventional phase noise mitigation algorithm can be enhanced using the proposed SNR estimation. The effectiveness of the proposed analysis and SNR estimation algorithm is verified through the link-level simulation. Compared with the conventional SNR estimation and the iterative phase noise mitigation algorithms, the proposed algorithm provides a lower packet-error rate without any iterative decoding process.
关键词： SNR analysis,phase noise mitigation,millimetre-wave,channel estimation,SC-FDE systems,packet-error rate
更新于2025-09-23 15:23:52
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Spectral Optimization to Minimize Light Absorbed by Artwork
摘要： Light is needed to appreciate artwork, but visible radiation causes damage by photochemical action. Photons trigger photochemical action only when they are absorbed by the object. Damage to sensitive materials can be reduced by optimizing the spectrum of a light source to the reflectance factor of a museum artifact. Absorption minimization approaches can be utilized to quantify and optimize typically conflicting parameters, such as damage due to light absorption, color quality of artwork, and energy consumption. In this project, seven narrowband light emitting diodes (LEDs) are optimized using a multi-objective genetic algorithm to reduce light absorption and energy consumption, while maintaining the color appearance of five paints (blue, green, yellow, orange, red). Results indicate that optimized test spectra can reduce light absorption between 18% and 48%, without causing perceptible color or hue shifts in the paintings. Parallel to absorption, energy consumption is almost halved for all of the paints (between 42% and 48%). Optimizing the light source spectrum can aid in conservation of art collections in museums by reducing damage caused by optical radiation while preserving color fidelity.
关键词： color perception,LED sources and systems,Art conservation,museum lighting,color rendition
更新于2025-09-23 15:23:52
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A New Biscarbazole-Based Metal-Organic Framework for Efficient Host-Guest Energy Transfer
摘要： A new metal–organic framework (MOF), [Zn6L4(Me2NH2+)4·3 H2O] (1) was constructed based on [9,9’-biscarbazole]-3,3’,6,6’-tetracarboxylic acid (H4L) and Zn2+ ions. The porous framework and intense blue fluorescence of the MOF based on the biscarbazole moiety of the ligand could facilitate efficient host to guest energy transfer, which makes it an ideal platform for the tuning of luminescence.
关键词： in situ encapsulation,metal–organic frameworks,energy transfer,host–guest systems,fluorescence
更新于2025-09-23 15:23:52
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PAPR reduction in all-optical OFDM based on time interleaving odd and even subcarriers
摘要： In this paper, a new all-optical approach for reducing peak-to-average power ratio (PAPR) in all-optical orthogonal frequency division multiplexing (AO-OFDM) system based on time interleaving odd and even subcarriers (TIOES) is proposed and analytically modeled. In this approach, all subcarriers are initially modulated with higher modulation format such as m-array quadrature amplitude modulation (mQAM) and encoded by return-to-zero (RZ) coder. Then, odd and even subcarriers are temporally interleaved. An analytical model for estimating the impact of the interleaved time on PAPR reduction and induced nonlinear phase noise (NPN) is developed. The effect of reducing PAPR on performance of AO-OFDM system is also numerically investigated using VPItransmissionMaker? commercial software. This system utilizes an optical coupler-based inverse fast Fourier transform/fast Fourier transform. The results reveal that minimum PAPR is occurred when interleaved time between odd and even subcarriers equal to half symbol duration where the PAPR has been reduced by 3 dB. In addition, by employing proposed technique, the signal to noise ratio (SNR) is improved by about 2.5 dB at transmission distance of 800 km as compared with 4QAM AO-OFDM without PAPR technique.
关键词： PAPR reduction,mQAM modulation,Nonlinear phase noise,Fiber nonlinearity,AO-OFDM systems
更新于2025-09-23 15:23:52
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Development and first in-human use of a Raman spectroscopy guidance system integrated with a brain biopsy needle
摘要： Navigation-guided brain biopsies are the standard of care for diagnosis of several brain pathologies. However, imprecise targeting and tissue heterogeneity often hinder obtaining high-quality tissue samples, resulting in poor diagnostic yield. We report the development and first clinical testing of a navigation-guided fiberoptic Raman probe that allows surgeons to interrogate brain tissue in situ at the tip of the biopsy needle, prior to tissue removal. The 900μm diameter probe can detect high spectral quality Raman signals in both the fingerprint and high wavenumber spectral regions with minimal disruption to the neurosurgical workflow. The probe was tested in 3 brain tumor patients, and the acquired spectra in both normal brain and tumor tissue demonstrated the expected spectral features, indicating the quality of the data. As a proof-of-concept, we also demonstrate the consistency of the acquired Raman signal with different systems and experimental settings. Additional clinical development is planned to further evaluate the performance of the system and develop a statistical model for real-time tissue classification during the biopsy procedure.
关键词： biopsy,cancer,neurosurgery,optical systems,Raman spectroscopy,medical imaging
更新于2025-09-23 15:23:52
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Energy disorder and energy level alignment between host and dopant in organic semiconductors
摘要： Energy level alignment between host and dopant molecules plays a critical role in exciton formation and harvesting in light emission zone of organic light-emitting diodes. Understanding the mechanism for predicting energy level alignment is thus important in materials selection for fabricating high-performance organic light-emitting devices. Here we show that host-dopant energy level alignment strongly depends on film thickness and substrate work function by using X-ray and ultraviolet photoemission spectroscopy. Invariant Gaussian density of states fails to explain the experimental data. We speculate that energy disorder in molecules next to the surface dictates the alignment. Ultraviolet photoemission spectroscopy measurements of several archetypical organic semiconductors confirm our speculation. An empirical interface disorder function is derived and used to construct a functional Gaussian density of states to compute host energy levels. Host-dopant energy level alignment is then computed by applying the universal energy alignment rule and is found in excellent agreement with the experimental data.
关键词： Host-dopant systems,Organic semiconductors,Energy level alignment,Photoemission spectroscopy,Energy disorder
更新于2025-09-23 15:23:52
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Mapping the thermal structure and minor species of Venus mesosphere with ALMA submillimeter observations
摘要： Context. Water vapor and sulfur compounds are key species in the photochemistry of Venus mesosphere. These species, together with mesospheric temperatures, exhibit drastic temporal variations, both on short timescales (diurnal and day-to-day) as well on long timescales, far from being understood. Aims. We targeted CO, SO, HDO and SO2 transitions in the submillimeter range using the Atacama Large Millimeter Array (ALMA) to study their spatial and temporal variations. Methods. Four sets of observations were acquired on different dates in November 2011 during the first ALMA Early Science observation Cycle 0. Venus angular diameter was about 11'' with an illumination factor of 92%, so that mostly the day side of the planet was mapped. Assuming a nominal CO abundance profile, we retrieved vertical temperature profiles over the entire disk as a function of latitude and local time. Temperature profiles were later used to retrieve SO, SO2, and H2O. We used HDO as a tracer for water assuming a D/H enrichment of 200 times the terrestrial value. Results. We derived 3D maps of mesospheric temperatures in the altitude range 70?105 km. SO, SO2, and H2O are characterized by a negligible abundance below ～85 km followed by an increase with altitude in the upper mesosphere. Disk-averaged SO abundances present a maximum mixing ratio of 15.0 ± 3.1 ppb on November 26 followed the next day by a minimum value of 9.9 ± 1.2 ppb. Due to a very low S/N, SO2 could only be derived from the disk-averaged spectrum on the first day of observation revealing an abundance of 16.5 ± 4.6 ppb. We found a SO2/SO ratio of 1.5 ± 0.4. Global maps of SO reveal strong variations both with latitude and local time and from day to day with abundance ranging from <1 to 15 ppb. H2O disk-averages retrievals reveal a steady decrease from November 14 to 27, with the abundance varying from 3.6 ± 0.6 ppm on the first day to 2.9 ± 0.7 ppm on the last day. H2O maps reveal a slightly higher abundance on the evening side compared to the morning side and a strong depletion between the first and the second day of observation.
关键词： planets and satellites: individual: Venus,methods: data analysis,planets and satellites: atmospheres,submillimeter: planetary systems,instrumentation: interferometers,radiative transfer
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE 2nd Colombian Conference on Robotics and Automation (CCRA) - Barranquilla, Colombia (2018.11.1-2018.11.3)] 2018 IEEE 2nd Colombian Conference on Robotics and Automation (CCRA) - Modeling and Simulation of a Grid-Tied 21.0 kWp Real Solar Power Plant as Case Study, Using the VHDL-AMS Language
摘要： This paper presents the utilization of hardware description language VHDL-AMS (Very High-Speed Integrated Circuit plus Hardware Description Language that includes analog and mixed-signal extensions) for modeling and simulation a grid-tied 21.0 kWp real solar power plant, admitted as case study. The case study used in this research consists of a photovoltaic power system with the following features: 1) It has 90 panels of 255 Wp and 3 SMA On Grid inverters, 2) It operates without batteries, and 3) It has a dynamic power controller, called Circuitor (CDP-0), to guarantee zero injection into the grid. The main contribution of this work is modeling and simulation of a grid-tied real solar power plant, using the VHDL-AMS language (with the support of software SystemVision?), in order to develop a simulating tool capable to find the real electrical energy generation in a photovoltaic system, considering the monthly averaged direct normal radiation and the solar panel characteristics. This paper aims to present the first major developments for the future construction of a bigger VHDL-AMS tool that will allow the simulation of photovoltaic power systems, operating in a synergic way with hydroelectric power plants previously built, with the aim of optimize the coordinated operation between hydropower and solar energy, for periods of rain and hydrological drought.
关键词： Solar Power Plant,Hardware description languages,VHDL-AMS Language,Photovoltaic systems
更新于2025-09-23 15:23:52