- 标题
- 摘要
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- 实验方案
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Effects of Environmental Atmosphere on the Performance of Contact–Separation Mode TENG
摘要： With great potential applications, triboelectric nanogenerator (TENG), is widely studied from various aspects, while systematic investigations about the effects of environmental atmosphere on its performance remain to be carried out. Here, a test system based on a piston-structured TENG and one-way valve gas line is built, employing the contact–separation mode. A series of tests about short-circuit transfer charges (QSC) and open-circuit voltage (VOC) are studied among three kinds of dielectric materials (PTFE, Kapton, PET), in five pure gases (N2, O2, CO2, Ar, He). At a static gas flow rate of 3 L min?1 or static gas pressure of 6 kPa above 1 atm, multicycle statistics demonstrate that TENGs achieve the highest performance in CO2 and the lowest in He. Meanwhile, Kapton-based TENG shows the greatest disparity in different atmosphere, followed by PET-based TENG, and PTFE-based TENG. A microscale discharge mechanism is introduced to explain all the above. Moreover, a negative linear relationship between QSC and the static gas pressure above 1 atm is found. This study is an important reference for a high-performance TENG configuration and device packaging in the future.
关键词： microscale discharge,performance,piston structure,environmental atmosphere,triboelectric nanogenerator
更新于2025-09-04 15:30:14
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Enhanced Visible Light Sensitization of N-doped TiO2 Nanotubes Containing Ti-Oxynitride Species Fabricated via Electrochemical Anodization of Titanium Nitride
摘要： The concentration and chemical state of nitrogen represent critical factors to control the band-gap narrowing and the enhancement of visible light harvesting in nitrogen-doped titanium dioxide. In this study, photocatalytic TiO2-N nanoporous structures were fabricated by the electrochemical anodization of titanium nitride sputtered films. Doping was straightforwardly obtained by oxidizing as-sputtered titanium nitride films containing N-metal bonds varying from 7.3 to 18.5 % in the Ti matrix. Severe morphological variations into the as-anodized substrates were registered at different nitrogen concentration and studied by Small-Angle X-ray Scattering. Titanium nitride films with minimum N content of 6.2 at% N led to a quasi-nanotubular geometry, whilst an increase in N concentration up to 23.8 at% determined an inhomogeneous, polydispersed distribution of nanotube apertures. The chemical state of nitrogen in the TiO2 matrix was investigated by X-ray Photoelectron Spectroscopy depth profile analysis and correlated to the photocatalytic performance. The presence of Ti-N and β-Ti substitutional bonds, as well as Ti-oxynitride species was revealed by the analysis of N 1s X-ray Photoelectron Spectroscopy High Resolution spectra. The minimum N content of 4.1 at% in the TiO2-N corresponded to the lowest Ti-oxynitride ratio of 13.5 %. The relative variation of N-metal bonds was correlated to the visible light sensitization and the highest Ti-N/Ti oxynitride ratio of 3.3 was attributed to the lowest band-gap of 2.7 eV and associated to a threefold increase in the degradation of organic dye. Further increase of N doping led to a dramatic drop of Ti-N/Ti oxynitride ratio, from 3.3 to 0.4, which resulted in a loss photocatalytic activity. The impact of the chemical state of nitrogen towards efficient doping of TiO2 nanotubes is demonstrated with a direct correlation to the N loading and a strategy to optimise these factors based on a simple, rapid synthesis from titanium nitride.
关键词： visible light sensitization,photocatalytic performance,titanium nitride,nitrogen-doped titanium dioxide,electrochemical anodization
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Study and Comparison for Different MIMO Antenna Performance Evaluation Methods
摘要： Different methods of MIMO antenna performance evaluation are proposed and verified. The ergodic channel capacity and system throughput can be both used to evaluate MIMO antenna performance. Both methods not only combined the antenna efficiency and correlation, but also considered the channel environment to fully evaluate the MIMO antenna performance in any environment and operating scenarios. Ergodic channel capacity calculation provides the upper limit of a MIMO antenna’s performance in some chosen environment and the results have good consistency for different SNRs and different channel environments. System throughput simulation also can be utilized to evaluate MIMO antenna performance and the simulation results show good agreement with channel capacity calculation results. The evaluation methods can be completed by simulation, which can save time for antenna design and optimization.
关键词： MIMO antenna,ergodic capacity efficiency,antenna performance,system throughput
更新于2025-09-04 15:30:14
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The Phase1 CMS Pixel detector upgrade
摘要： The pixel detector of the CMS experiment will be replaced in an extended end-of-year shutdown during winter 2016/2017 with an upgraded one able to cope with peak instantaneous luminosities beyond the nominal LHC instantaneous luminosity of 1 × 1034 cm?2 s?1. Under the conditions expected in the coming years, which will see an increase of a factor two in instantaneous luminosity, the present system would experience a dynamic ine?ciency caused mainly by data losses due to bu?er over?ows. The Phase I upgrade of the CMS pixel detector, described in this paper, will operate at full e?ciency at an instantaneous luminosity of 2 × 1034 cm?2 s?1 and beyond, thanks to a new readout chip. The new detector will feature one additional tracking point both in the barrel and in the forward regions, while reducing the material budget as a result of a new CO2 cooling system and optimised layout of the services. In this paper, the design and the technological choices of the Phase I detector will be reviewed and the status of the construction of the detector and the performance of its components will be discussed.
关键词： Particle tracking detectors,Radiation-hard detectors,Performance of High Energy Physics Detectors,Si microstrip and pad detectors
更新于2025-09-04 15:30:14
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[IEEE 48th European Solid-State Device Research Conference (ESSDERC 2018) - Dresden (2018.9.3-2018.9.6)] 2018 48th European Solid-State Device Research Conference (ESSDERC) - Compact Modeling for Power Efficient Circuit Design
摘要： Reduction of power loss in circuit operation is an urgent task to save energy. For this purpose accurate prediction of the device-level power loss is a prerequisite. The core compact modeling approach is presented, which can be easily extended to include non-ideal effects to be considered. With use of the developed model it is demonstrated that any phenomena, which prevent the gate control, become the origin of an increased power loss. An optimization scheme for achieving low power loss, based on the presented compact modeling approach, is discussed with basic circuits.
关键词： power loss,MOSFETs,carrier dynamics,compact modeling,circuit performance
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Towards Performance Optimisation of the FDTD Method via Matrix Casting Approach
摘要： This publication presents matrix casting approach for the FDTD method. Applied in 2D and 3D dimensions it is subsequently parallelised with OpenMP and tested in basic air-filled and realistic landmine-detection scenarios.
关键词： performance analysis,finite difference methods,numerical simulation,electromagnetic propagation
更新于2025-09-04 15:30:14
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[IEEE 2018 11th International Symposium on Communication Systems, Networks and Digital Signal Processing (CSNDSP) - Budapest (2018.7.18-2018.7.20)] 2018 11th International Symposium on Communication Systems, Networks & Digital Signal Processing (CSNDSP) - Modeling and Throughput Analysis of FSO Systems using GBN-ARQ and AR Transmission over Atmospheric Turbulence Channels
摘要： This paper addresses the error-control issue in free-space optical (FSO) communications. In particular, we model and analyze the throughput performance of FSO systems over atmospheric fading channel when the go-back-N (GBN) automatic repeat request (ARQ) and adaptive rate (AR) transmission schemes are employed. For this purpose, we first build the model to capture the time-varying behavior in atmospheric fading channels. We then use that channel model to develop the burst error model for GBN-ARQ with AR in order to analytically derive the system throughput. Numerical results quantitatively show the impacts of atmospheric turbulence on the throughput and confirm the effectiveness of the GBN/ARQ. Monte Carlo simulations are also performed to validate the analytical results.
关键词： throughput performance,go-back-N (GBN) automatic repeat request (ARQ),atmospheric turbulence,adaptive rate (AR) transmission,Free-space optical (FSO) communications
更新于2025-09-04 15:30:14
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UAV Scale Coaxial Rotor Aerodynamic Interactions Investigation Through High-Speed PIV and Performance Measurements
摘要： Coaxial rotor UAVs are compact compared to single rotor UAVs of comparable capacity. At the low Reynolds Numbers (Re) where they operate, the simplifying assumptions from high Re rotor aerodynamics are not valid. The low Re coaxial rotor ?ow?eld is studied including aerodynamic interactions and their effect on performance. The evolution of the wake is captured using high speed Stereo Particle Image Velocimetry (SPIV). Improvement of upper rotor performance due to viscous swirl recovery from the lower rotor is discovered and then veri?ed by analyzing PIV data. Interesting vortex - vortex sheet interactions are observed under the coaxial rotor affecting wake structure spatially and temporally. A qualitative model explaining the observed wake interaction phenomena is presented. Comparison with the performance of high Re rotors shows higher pro?le and induced drag at low Re for the same thrust coef?cient.
关键词： Viscous swirl recovery,High-speed PIV,Aerodynamic interactions,Performance measurements,Low Reynolds number,Coaxial rotor,Vortex-vortex sheet interactions,UAV
更新于2025-09-04 15:30:14
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Optimizing the oxygen balance by changing the A-site cations in molecular perovskite high-energetic materials
摘要： We presented two new members of molecular perovskite high-energetic materials, (H2pz)[Na(ClO4)3] (PAP-1) and (H2dabco-O)[K(ClO4)3] (DAP-O2), in which H2pz2+ (piperazine-1,4-diium) and H2dabco-O2+ (1-hydroxy-1,4-diazabicyclo[2.2.2]octane-1,4-diium) act as A-site fuel cations, respectively. Compared with their H2dabco2+ analogues, (H2dabco)[M(ClO4)3] (M = Na+ for DAP-1 and K+ for DAP-2, respectively), PAP-1 and DAP-O2 exhibit optimized oxygen balance by employing two strategies to change the A-site cations, i.e., “trimming the C and H atoms” of H2dabco2+ by using H2pz2+ to form PAP-1 and adding an O atom into H2dabco2+ by using H2dabco-O2+ to form DAP-O2, respectively. As suggested by DFT calculations and the K–J equation, the smaller H2pz2+ cation in PAP-1 gives a significantly-optimized oxygen balance from ?22.0% to ?3.9% and an increased crystal density from 2.02 to 2.07 g cm?3, resulting in a better detonation performance for PAP-1. Meanwhile the larger H2dabco-O2+ cation gives a slightly-optimized oxygen balance from ?21.3% to ?17.1% but a decreased crystal density from 2.04 to 1.98 g cm?3, leading to a decreased detonation performance from DAP-2 to DAP-O2. This study demonstrated how to rationally choose the A-site cations in a perovskite structure for modulating the properties of molecular perovskite high-energetic materials, providing important clues for designing more advanced energetic materials for practical use.
关键词： high-energetic materials,oxygen balance,molecular perovskite,detonation performance,A-site cations
更新于2025-09-04 15:30:14
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[IEEE 2018 26th European Signal Processing Conference (EUSIPCO) - Roma, Italy (2018.9.3-2018.9.7)] 2018 26th European Signal Processing Conference (EUSIPCO) - Performance Evaluation of N O- Reference Image Quality Metrics for Visible Wavelength Iris Biometric Images
摘要： Image quality assessment plays an important role in iris recognition systems because the system performance is affected by low quality iris images. With the development of electronic color imaging, there are more and more researches about visible wavelength (VW) iris recognition. Compared to the near infrared iris images, using VW iris images acquired under unconstrained imaging conditions is a more challenging task for the iris recognition system. However, the number of quality assessment methods for VW iris images is limited. Therefore, it is interested to investigate whether existing no-reference image quality metrics (IQMs) which are designed for natural images can assess the quality of VW iris images. In this paper, we evaluate the performance of 15 selected no-reference IQMs on VW iris biometrics. The experimental results show that several IQMs can assess iris sample quality according to the system performance.
关键词： image quality assessment,visible wavelength iris,image based attributes,performance evaluation,multi-modality
更新于2025-09-04 15:30:14