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Effect of PET-MR Inconsistency in the Kernel Image Reconstruction Method
摘要： Anatomically-driven image reconstruction algorithms have become very popular in positron emission tomography (PET) where they have demonstrated improved image resolution and quantification. This work, consider the effect of spatial inconsistency between MR and PET images in hot and cold regions of the PET image. We investigate these effects on the kernel method from machine learning, in particular, the hybrid kernelized expectation maximization (HKEM). These were applied to Jaszczak phantom and patient data acquired with the Biograph Siemens mMR. The results show that even a small shift can cause a significant change in activity concentration. In general, the PET-MR inconsistencies can induce the partial volume effect, more specifically the 'spill-in' of the affected cold regions and the 'spill-out' from the hot regions. The maximum change was about 100% for the cold region and 10% for the hot lesion using KEM, against the 37% and 8% obtained with HKEM. The findings of this work suggest that including PET information in the kernel enhances the flexibility of the reconstruction in case of spatial inconsistency. Nevertheless, accurate registration and choice of the appropriate MR image for the creation of the kernel is essential to avoid artifacts, blurring, and bias.
关键词： hybrid kernel,image prior,expectation maximization (EM),kernel method,positron emission tomography (PET),iterative reconstruction,anatomically-driven
更新于2025-09-09 09:28:46
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Dimensionality engineering of hybrid halide perovskite light absorbers
摘要： Hybrid halide perovskite solar cells were first demonstrated in 2009 with cell efficiency quickly soaring from below 10% to more than 23% in a few years. Halide perovskites have the desirable processing simplicity but are very fragile when exposed to water and heat. This fragility represents a great challenge for the achievement of their full practical potential in photovoltaic technologies. To address this problem, here we review the recent development of the mixed-dimensional perovskites, whereby the trade-off between power conversion efficiency and stability of the material can be finely tuned using organic amine cations with different sizes and functionalities.
关键词： hybrid halide perovskite,organic amine cations,stability,mixed-dimensional perovskites,solar cells,power conversion efficiency
更新于2025-09-09 09:28:46
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The Nature of the Oxygen Vacancy in Amorphous Oxide Semiconductors: Shallow Versus Deep
摘要： Using first-principles calculation, we investigate the nature of oxygen vacancy (VO), namely shallow versus deep, in the amorphous oxide semiconductor InGaZnO4 (a-IGZO), which has not been fully clarified despite its technological importance. Oxygen-deficient amorphous models are generated through the hybrid functional molecular dynamics (MD) simulations that allow for finding stable VO configurations while minimizing computational approximations. From eight independent models, we consistently find that VO serves as the shallow donor, increasing the Fermi level above the conduction band minimum. For comparison purpose, we also generate deep VO models by charging the system during MD simulations. It is found that deep VO is higher in the formation energy than shallow VO, confirming that shallow VO is the preferred type of oxygen vacancies in a-IGZO.
关键词： hybrid functional,computational physics,InGaZnO4,oxygen vacancy,density functional theory
更新于2025-09-09 09:28:46
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Experimental investigation and CFD analysis of a solar hybrid PV/T system for the sustainable development of the rural northern part of Bangladesh
摘要： An attempt has been made to utilise solar energy more e?ciently by developing the single pass hybrid photovoltaic thermal system at the climatic condition of Bangladesh. As the electric energy conversion e?ciency of the photovoltaic module falls with the surrounding temperature and air or water used as a suitable solution to make it cool. In this study, air was used as the cooling medium for the solar panel and circular copper tube was placed on the glazed collector for water heating to ensure maximum exploitation of solar energy. Moreover, the photovoltaic panel power was used to circulate the air and make the system self-powered. Maximum collector e?ciency was 24.64% for water and 11.20% for air is observed at a mass ?ow rate 0.00158 and 0.00221 kg/s for water and air respectively at a solar radiation of 1050 W/m2. In addition, the combined e?ciency of the hybrid system was about 39.68%. By adding glycerin with water at a ratio of 50:1 (% of weight) the combined e?ciency reached up to 45.76%. The computational ?uid dynamics (CFD) simulation and economic analysis of the designed system strongly support the feasibility of the solar hybrid photovoltaic thermal system as the future sustainable energy source.
关键词： CFD simulation,Solar energy,feasibility analysis,hybrid PV/T
更新于2025-09-09 09:28:46
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Facial construction of defected NiO/TiO2 with Z-scheme charge transfer for enhanced photocatalytic performance
摘要： Here we report a defected NiO/TiO2 composite (NiO/TiO2-OV) fabricated by a two-step hydrothermal method with the followed one-step calcination, which induced the in situ generation of Ti3+ and oxygen vacancies, coupled with the construction of a direct Z-scheme band structure. The NiO/TiO2-OV catalyst exhibited a substantially improved performance in the photodegradation of organic pollutant and photocatalytic hydrogen evolution reaction (HER). The sensitization by narrow bandgap semiconductor of NiO enhanced the light response of catalysts. More importantly, the intrinsic defects, the Ti3+ and oxygen vacancies, acted as the mid-gap state in TiO2, and resulted in the direct Z-scheme charge transfer between the Ti3+/oxygen vacancies state and the valance band (VB) of NiO to suppress the recombination of photogenerated electrons and holes. Meanwhile, the realignment of band structure caused by constructing NiO/TiO2 heterojunction made the photogenerated carries more active in the photocatalytic reduction and oxidation reactions.
关键词： Z-scheme charge transfer,NiO/TiO2 hybrid,Photocatalysis,Surface defects,Self-doping of Ti3+
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE Photonics Conference (IPC) - Reston, VA, USA (2018.9.30-2018.10.4)] 2018 IEEE Photonics Conference (IPC) - THz Photonic Transmitters with Type-II Hybrid Absorber UTC-PDs and Dual-Ridged Horn Antennas for High-Power and Extremely wide Fractional Bandwidth Performances
摘要： Waveguide-coupled THz photonic transmitters, which have novel design of dual-ridged horn antenna and ultra-fast photodiodes, demonstrate extremely wide 3-dB fractional O-E bandwidth (100%; 0.1-0.3 THz). A reasonable power (31.6 μW; 0.24 THz) can be detected in the receiving-end through wireless transmission.
关键词： Extremely wide fractional bandwidth,High-power,THz photonic transmitters,Dual-ridged horn antennas,Type-II hybrid absorber UTC-PDs
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Chengdu (2018.3.26-2018.3.28)] 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Control Enhancement of Dipole Emission Using Hybrid Metal-Dielectric Nanoantenna
摘要： A novel hybrid nanoantenna comprising a stack of two cylinders is proposed to control the enhancement of the dipole emission. The bottom cylinder is made of plasmonic metal to generate large field enhancement to boost the excitation rate of the dipole. The top cylinder is made of high permittivity low loss dielectric to enhance the far field emission intensity of the dipole while maintaining high quantum efficiency. The design principle revealed here can be extended to other geometries and is beneficial to the research fields such as fluorescence enhancement, Raman spectroscopy, and single photon source, among others.
关键词： Nanoantenna,dipole radiation,Hybrid,low loss,enhancement
更新于2025-09-09 09:28:46
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Synthesis of Inorganic/Organic Hybrid Materials via Vapor Deposition onto Liquid Surfaces
摘要： Hybrid materials have a multitude of uses in electronics, catalysis, and drug delivery. Here, we combine sputter deposition and initiated chemical vapor deposition onto low-vapor-pressure liquids to fabricate inorganic/organic hybrid materials. We demonstrate that polymer nanoparticles can be decorated with metal nanoparticles and nanoparticle dispersions can be encapsulated within polymer shells or within gel beads. The generality of our synthetic route allows for a variety of hybrid materials to be fabricated by tuning the viscosity of the liquid, solubility of the monomer, and surface tension of the polymer and liquid.
关键词： encapsulation,polymer,hybrid,nanoparticles,hydrogels,synthesis
更新于2025-09-09 09:28:46
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COMPACT TRI-BAND BANDPASS FILTER BASED ON HYBRID RESONATOR WITH IMPROVED SELECTIVITY PERFORMANCES
摘要： A novel microstrip tri-band bandpass ?lter is proposed and implemented using hybrid resonator with independently controllable center frequencies and good in-between isolation. This hybrid resonator is constructed by a stepped-impedance stub resonator and a single end shorted resonator. The stepped-impedance stub resonators are applied to achieve the ?rst and second passband, while the third passband is implemented by single end shorted resonators. By applying the even-odd mode approach, the resonance frequency ratio between even mode and odd mode inside the stepped-impedance stub resonators is attained. Furthermore, the ?lter with multi-path coupling structure can generate the transmission zeros at the edge of the passband, which can e?ectively improve the ?lter passband selectivity. Finally, a tri-band ?lter operating at 1.91, 2.73, and 3.45 GHz is designed and fabricated. The measurement results accord well with the full-wave electromagnetic designed responses.
关键词： single end shorted resonator,multi-path coupling structure,hybrid resonator,tri-band bandpass ?lter,stepped-impedance stub resonator
更新于2025-09-09 09:28:46
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DoA and DoD Estimation and Hybrid Beamforming for Radar-Aided mmWave MIMO Vehicular Communication Systems
摘要： In millimeter wave (mmWave) communications, the feature of relatively large signal absorption and directional transmission render new challenges for wireless communications and signal processing. To further improve the performance of mmWave communications, a novel radar-aided mmWave communication (RAMC) approach is proposed, which can be used in vehicular communications. There are two parts in the proposed RAMC system, including the radar subsystem and the mmWave communication subsystem. In the radar subsystem, the bistatic co-prime multi-input and multi-output (MIMO) arrays are considered. With the radar antenna arrays, both the directions of departure (DoD) and the directions of arrival (DoA) are estimated. Additionally, the compressed sensing (CS)-based method is proposed to obtain the target positions. Using the estimated angle and position information, the channel estimation and feedback link of the mmWave communication subsystem can be eliminated. Moreover, a hybrid beamforming algorithm is proposed in the mmWave communication subsystem, which can overcome the shortage of the analog-only beamforming. Simulation results show that the better estimation performance can be achieved by the bistatic co-prime MIMO arrays than that by the traditional uniform linear arrays (ULA), and with the radar aided, the mmWave communication subsystem can reduce the beam search time, and the cell discovery time is improved significantly.
关键词： compressed sensing,millimeter wave,hybrid beamforming,DoA estimation,radar
更新于2025-09-09 09:28:46