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- 摘要
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- 实验方案
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Numerical simulation and experimental analysis of an LCPV/T system under real operating conditions
摘要： In this study the performance evaluation of a low concentration photovoltaic/thermal (LCPV/T) module under different operating conditions (fixed flow & outlet temperature) was carried out, numerically and experimentally. In addition, the influences of individual parameters on module performance were also studied. All experiments showed that both the electrical and thermal output first increased and then decreased with time. The maximum experimental values were 470 W and 1916 W, respectively. The electrical and thermal efficiencies, however, first decreased and then increased with time. The maximum respective experimental values were 17.28% and 59.84%. The results also indicated that in general, there were errors of 10%e20% between the theoretical and experimental values. Therefore, modification coefficients were determined to correct the theoretical model. The results showed that the relative error between the modified theoretical value and the experimental value is stable within 5%.
关键词： Performance analysis,Simulation & experiment,LCPV/T,Error correction
更新于2025-09-10 09:29:36
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readout chip
摘要： In order to solve the leakage current saturation of Topmetal-???? ? and to maintain its low noise, Topmetal-?????? has been designed. The new chip has the same Rolling-Shutter module as Topmetal-???? ?. It contains a charge-collection electrode and a metal layer surrounding it, called guard ring. This new design contains three different sections. Section A has the same structure as Topmetal-???? ?, in that the electrode is exposed and guard ring is covered by insulating layer. Section B has both electrode and guard ring exposed. Section C has guard ring exposed but electrode covered by insulating layer. Preliminary experiments show that if coupled with CdZnTe detector, Section C of the Topmetal-?????? chip is capable of solving the leakage current saturation. Meanwhile, the electrode receives induced signal. Moreover, the charge induction efficiency is influenced by several parameters, such as thickness of adhesive epoxy resin, collecting electrode size, etc. Thus, the optimization of parameters for induction efficiency is studied by simulations. According to the simulation results, it can be concluded that thinner epoxy resin thickness and bigger anode size contribute to higher induction efficiency.
关键词： Leakage current,CdZnTe,Induced signal simulation,Topmetal,Low noise readout chip,Pixel
更新于2025-09-10 09:29:36
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Stable Structural Phase of Potassium-Doped <i>p</i> -Terphenyl and Its Semiconducting State
摘要： The potassium-doped p-terphenyl compounds were synthesized in recent experiments and the superconductivity with high transition temperatures were reported, but the atomic structure of potassium-doped p-terphenyl is unclear. In this paper, we studied the structural and electronic properties of potassium-doped p-terphenyl with various doping levels by the first-principles simulation. We first find out the low energy position of K atom in intralayer interstitial space of the molecular layer, then examine whether two rows of K atoms can be accommodated in this one space, at last the effect of the interlayer arrangement between adjacent two molecular layers on total energy is taken into account. Our results show that the doped K atoms prefer to stay at the bridge site of single C-C bond connected two phenyls instead of locating at the site above the phenyl ring, distinct from the situation of K-doped picene and phenanthrene. Among the possible structural phases of Kx-p-terphenyl, the K2-p-terphenyl phase with P212121 group symmetry is determined to be most appropriate, which is different from the one in recent report. The stable K2-p-terphenyl phase is semiconducting with an energy gap of 0.3 eV and the bands from the lowest unoccupied molecular orbitals are just fully filled by the electrons transferred from K atoms.
关键词： Plasmonics,First-principles simulation,Semiconducting state,Magnetic,Potassium-doped p-terphenyl,Superconductivity,Optical,Hybrid Materials
更新于2025-09-10 09:29:36
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[IEEE 2018 15th European Radar Conference (EuRAD) - Madrid, Spain (2018.9.26-2018.9.28)] 2018 15th European Radar Conference (EuRAD) - Simulation of Near Field RCS to Reproduce Measurement Condition
摘要： Different approaches are presented to simulate the near field Radar Cross Section (RCS) of a perfectly conducting electrically large object. This type of environment is usually found in measurements at large anechoic chambers where the far field condition cannot be achieved, making it impossible to approximate the incident field by a planewave. Each approach will be implemented with Physical Optics (PO) for extremely large targets and an accelerated version of the Method of Moments for moderately large objects. The fast MoM method are either the Multilevel Adaptive Cross Approximation (MLACA) for an iterative solution or the Multiscale Compressed Block Decomposition (MSCBD) for a direct solution. This development and the performed simulations have been done with CAPITOLE-RCS commercial software developed by NEXIO.
关键词： physical optics,method of moments,radar cross-sections,inverse synthetic aperture radar,Numerical simulation,anechoic chambers
更新于2025-09-10 09:29:36
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[IEEE 2018 International Power Electronics Conference (IPEC-Niigata 2018 –ECCE Asia) - Niigata, Japan (2018.5.20-2018.5.24)] 2018 International Power Electronics Conference (IPEC-Niigata 2018 -ECCE Asia) - Modeling and model parameter extraction of wide bandgap power semiconductor device, package, and circuit for simulating fast switching behavior
摘要： Wide band gap power semiconductor devices have superiority in fast switching operation, when compared to Si IGBT and PiN diodes for voltage range from several hundred to several kilo volts. The fast switching operation gives high di/dt and dv/dt, which results in inducing surge voltage and EMI noise for poorly designed circuit. The precise dynamical model of power device and peripheral component is necessary in estimating these transient phenomenon. This paper presents the dynamical model of wide bandgap power semiconductor devices, package of power device, and circuit wiring. The fixture configurations to extract model parameter is also presented. The static blocking and conducting condition for power device is characterized with curve tracer. The terminal capacitance of power device dominates switching dynamic terminal characteristics. Then, voltage dependency of capacitances are characterized with the developed fixture, which can cope with normally on transistor characterization. The electro magnetic analysis of package and circuit to identify parasitic component is also addressed in the paper. The switching behaviors of power device and the phenomenon in the circuit are discussed based on the model and extracted model parameters.
关键词： parameter extraction,wide bandgap power semiconductor devices,modeling,fast switching behavior,simulation
更新于2025-09-10 09:29:36
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DESIGN AND SIMULATION OF ARBITRARILY-SHAPED TRANSFORMATION OPTIC DEVICES USING A SIMPLE FINITE-DIFFERENCE METHOD
摘要： A fast and simple design methodology for transformation optics (TO) is described for devices having completely arbitrary geometries. An intuitive approach to the design of arbitrary devices is presented which enables possibilities not available through analytical coordinate transformations. Laplace’s equation is solved using the ?nite-di?erence method to generate the arbitrary spatial transforms. Simple techniques are presented for enforcing boundary conditions and for isolating the solution of Laplace’s equation to just the device itself. It is then described how to calculate the permittivity and permeability functions via TO from the numerical spatial transforms. Last, a modi?cation is made to the standard anisotropic ?nite-di?erence frequency-domain (AFDFD) method for much faster and more e?cient simulations. Several examples are given at the end to benchmark and to demonstrate the versatility of the approach. This work provides the basis for a complete set of tools to design and simulate TO devices of any shape and size.
关键词： transformation optics,finite-difference method,Laplace’s equation,electromagnetic simulation,anisotropic materials
更新于2025-09-10 09:29:36
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Simulation and experiment of field emission based on carbon nanotubes
摘要： In view of the bearing current of motor, a method of suppressing the bearing current using the ?eld emission characteristics of carbon nanotubes is proposed. Firstly, the advantages of carbon nano-materials and their ?eld emission properties are introduced. Secondly, the in?uence of the distance between the emitter tips and the anode metal plate on the electric ?eld intensity is analyzed by software simulation. Finally, ?eld emission experiments of TNF300 type carbon nanotube ?bers under non vacuum conditions were carried out by means of probes, microscopes and other experimental equipment. After obtaining the voltage and current of carbon nano-materials at di?erent distances, the volt-ampere characteristic curves and the ?eld emission characteristic curve were drawn, and the experimental results from di?erent distances were compared and analyzed.
关键词： carbon nanotubes,bearing current suppression,simulation and experiment,Field emission
更新于2025-09-10 09:29:36
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Assessing the capability of different satellite observing configurations to resolve the distribution of methane emissions at kilometer scales
摘要： Anthropogenic methane emissions originate from a large number of fine-scale and often transient point sources. Satellite observations of atmospheric methane columns are an attractive approach for monitoring these emissions but have limitations from instrument precision, pixel resolution, and measurement frequency. Dense observations will soon be available in both low Earth and geostationary orbits, but the extent to which they can provide fine-scale information on methane sources has yet to be explored. Here we present an observation system simulation experiment (OSSE) to assess the capabilities of different satellite observing system configurations. We conduct a 1-week WRF-STILT simulation to generate methane column footprints at 1.3×1.3 km2 spatial resolution and hourly temporal resolution over a 290×235 km2 domain in the Barnett Shale in Northeast Texas, a major oil/gas field with a large number of point sources. We sub-sample these footprints to match the observing characteristics of the recently launched TROPOMI instrument (7×7 km2 pixels, 11 ppb precision, daily frequency), the planned GeoCARB instrument (2.7×3.0 km2 pixels, 4 ppb precision, nominal twice-daily frequency), and other proposed observing configurations. The information content of the various observing systems is evaluated using the Fisher information matrix and its eigenvalues. We find that a week of TROPOMI observations should effectively provide regional (～100 km) information on temporally invariant emissions but is very limited at finer scales. GeoCARB should provide 4-37% of the total information available for temporally invariant emissions in the Barnett Shale (～100 pieces of information). Improvements to the instrument precision yield greater increases in information content, compared to improved sampling frequency. A precision better than 6 ppb is an important threshold for achieving fine resolution of emissions. Transient emissions would be missed with either TROPOMI or GeoCARB. An aspirational high-resolution geostationary instrument with 1.3×1.3 km2 pixel resolution, hourly return time, and 1 ppb precision would effectively constrain the temporally invariant emissions in the Barnett Shale at the kilometer scale and provide some information on transient sources.
关键词： Fisher information matrix,GeoCARB,methane emissions,TROPOMI,satellite observations,WRF-STILT simulation
更新于2025-09-10 09:29:36
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Simulating terahertz absorption of fluorinated phenylacetylene biphenyl liquid crystal molecules
摘要： Based on the density functional theory, ten kinds of fluoro-substituted liquid crystal derivative molecules, 4-butyl-4’-[(4-butylphenyl)acetylene]biphenyl, are simulated using Gaussian09 package with Opt+Freq optimization type and B3LYP/6-311g basis set. Comparing the substituted position and number of fluorine atoms, the absorption in terahertz region is discussed. Because measurement data of liquid crystal material absorption is lacking, we can only compare in the range of 0.3?3 THz. The results show that the calculation results have the same trend as the experimental measurement absorption curve of related literature. As a conclusion, our calculations can better reflect the absorption of molecular materials and provide effective suggestions for the design and synthesis of related molecules.
关键词： Gaussian simulation,absorption,fluorine liquid crystal,spectrum,terahertz
更新于2025-09-10 09:29:36
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Evaluation of a spectral line width for the Phillips spectrum by means of numerical simulation
摘要： The work aims to check one of the assumptions under which the kinetic equation for water waves was derived in order to understand whether it can be applied to the situations described by the Phillips spectrum. We evaluate a spectral line width of the spectrum from the simulations in the framework of primordial dynamical equations at different levels of nonlinearity in the system, corresponding to the weakly turbulent Kolmogorov–Zakharov spectra ω?4, Phillips spectra ω?5, and intermediate cases. The original motivation of the work was to check one of the assumptions under which the kinetic equation for water waves was derived in order to understand whether it can be applied to the Phillips spectrum. It is shown that, even in the case of relatively high average steepness, when the Phillips spectrum is present in the system, the spectral lines are still very narrow, at least in the region of the direct cascade spectrum. It allows us to state that, even in the case of the Phillips spectrum, one of the assumptions used for the derivation of the Hasselmann kinetic equation is still valid, at least in the case of moderate whitecapping.
关键词： numerical simulation,water waves,Phillips spectrum,spectral line width,kinetic equation
更新于2025-09-10 09:29:36