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- 摘要
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- 实验方案
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Daily Variation Law of Solar Radiation Flux Density Incident on the Horizontal Surface
摘要： The instantaneous solar radiation flux density incident on the horizontal surface near the ground, consisted of three sections, direct radiation, scattered radiation, and thermal radiation flowing down through the atmosphere, directly or indirectly comes from the sun. The dynamics of the solar radiation flux density incident on the horizontal surface near the ground influence all life processes and environment. In this study, the daily variation law of solar radiation flux density incident on the horizontal surface developed. The results showed that generally, sky conditions is stable, and the daily dynamic in the solar radiation flux density incident on the horizontal surface near the ground is the function of time, and can be described by a normal distribution model in a day. The main parameters of the model change with date and the meteorological conditions in a day.
关键词： Environment,Diurnal total solar energy,Hour,Sky conditions,Solar radiation,Daily variation law,Horizontal surface,Flux density
更新于2025-09-09 09:28:46
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Deriving clear-sky longwave spectral flux from spaceborne hyperspectral radiance measurements: a case study with AIRS observations
摘要： Previous studies have shown that longwave (LW) spectral fluxes have unique merit in climate studies. Using Atmospheric Infrared Sounder (AIRS) radiances as a case study, this study presents an algorithm to derive the entire LW clear-sky spectral fluxes from spaceborne hyperspectral observations. No other auxiliary observations are needed in the algorithm. A clear-sky scene is identified using a three-step detection method. The identified clear-sky scenes are then categorized into different sub-scene types using information about precipitable water, lapse rate and surface temperature inferred from the AIRS radiances at six selected channels. A previously established algorithm is then used to invert AIRS radiances to spectral fluxes over the entire LW spectrum at 10 cm?1 spectral interval. Accuracy of the algorithms is evaluated against collocated Clouds and the Earth’s Radiant Energy System (CERES) observations. For nadir-view observations, the mean difference between outgoing longwave radiation (OLR) derived by this algorithm and the collocated CERES OLR is 1.52 Wm?2 with a standard deviation of 2.46 Wm?2. When the algorithm is extended for viewing zenith angle up to 45?, the performance is comparable to that for nadir-view results.
关键词： hyperspectral radiance measurements,longwave spectral flux,clear-sky detection,climate studies,AIRS
更新于2025-09-09 09:28:46
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Molten Steel Level Detection From Thermal Image Sequence Based on the Characteristics of Adhesive Flux
摘要： High-temperature medium and time-varying covering flux lead to the difficulty of molten steel level measurement. For the measurement, in our previous work, a novel principle by using temperature gradient was proposed by us, and a refractory sensor was inserted into the metallurgical container to sense the temperature gradients of the flux and the molten steel. However, sometimes liquid adhesive flux on the sensor surface disables the extraction of true temperature gradients. To fix this problem, two new models, the adhesion thickness model and the adhesion flowability model, which are inspired by the adhesion mechanism of the flux, are proposed to detect the steel-flux interface. A unified approach, sequential clustering of the shapes of the pixel gray-time curves, is introduced to conduct the detection. On this basis, the thermal image sequence with 4-D spacetime information of the sensor is used for clustering. First, gray values of each pixel in the sequence are sorted in the time dimension, and grouping of the pixels in space dimension is done. Then, the region of interest is extracted from the image sequence to remove the invalid pixels, and sequential clustering is conducted with each group. Finally, the confidence of the clustering results is measured and the clustering results with the confidence higher than the threshold are retained to detect the steel-flux interface. By utilizing the two new models, the standard deviation of the measurement errors reduces from 4.8 to 3.7 mm.
关键词： thermal image sequence,steel-flux interface detection,Adhesion characteristic,4-D spacetime information,sequential clustering
更新于2025-09-09 09:28:46
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Determining the Shortwave Radiative Flux From Earth Polychromatic Imaging Camera
摘要： The Earth Polychromatic Imaging Camera (EPIC) onboard Deep Space Climate Observatory provides 10 narrowband spectral images of the sunlit side of the Earth. The blue (443 nm), green (551 nm), and red (680 nm) channels are used to derive EPIC broadband radiances based upon narrowband-to-broadband regressions developed using collocated MODIS equivalent channels and Clouds and the Earth’s Radiant Energy System (CERES) broadband measurements. The pixel-level EPIC broadband radiances are averaged to provide global daytime means at all applicable EPIC times. They are converted to global daytime mean shortwave (SW) ?uxes by accounting for the anisotropy characteristics using a cloud property composite based on lower Earth orbiting satellite imager retrievals and the CERES angular distribution models (ADMs). Global daytime mean SW ?uxes show strong diurnal variations with daily maximum-minimum di?erences as great as 20 W/m2 depending on the conditions of the sunlit portion of the Earth. The EPIC SW ?uxes are compared against the CERES SYN1deg hourly SW ?uxes. The global monthly mean di?erences (EPIC-SYN) between them range from 0.1 W/m2 in July to ?4.1 W/m2 in January, and the RMS errors range from 3.2 to 5.2 W/m2. Daily mean EPIC and SYN ?uxes calculated using concurrent hours agree with each other to within 2% and both show a strong annual cycle. The SW ?ux agreement is within the calibration and algorithm uncertainties, which indicates that the method developed to calculate the global anisotropic factors from the CERES ADMs is robust and that the CERES ADMs accurately account for the Earth’s anisotropy in the near-backscatter direction.
关键词： angular distribution models,anisotropy,EPIC,shortwave radiative flux,CERES
更新于2025-09-09 09:28:46
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Automated characterization and quantification of hydrocarbon seeps based on frontal illuminated video observations
摘要： Hydrocarbon releases, either natural or due to anthropogenic activities, are of major relevance for the marine environment. In this work we specify our approach to quantify these seeps by subsea imaging utilizing camera systems and frontal illumination setups on board remotely operated vehicles. This work showcases, based on a campaign in the region west of Svalbard, improved methodological guidelines for the seep quantification operation together with a novel automated post-mission evaluation. The comparison of automated quantification with manual information extraction illustrates the efficiency of this new method while processing comparable estimates of seep characteristics.
关键词： gas flux,bubbles,Methane,imaging,Svalbard
更新于2025-09-09 09:28:46
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Application of Kinetic Flux Vector Splitting Scheme for Solving Viscous Quantum Hydrodynamical Model of Semiconductor Devices
摘要： In this article, one-dimensional viscous quantum hydro dynamical model of semiconductor devices is numerically investigated. The model treats the propagation of electrons in a semiconductor device as the flow of a charged compressible fluid. It plays an important role in predicting the behaviour of electron flow in semiconductor devices. The nonlinear viscous quantum hydrodynamic models contain Euler-type equations for density and current, viscous and quantum correction terms, and a Poisson equation for electrostatic potential. Due to high nonlinearity of model equations, numerical solution techniques are applied to obtain their solutions.. The proposed numerical scheme is a splitting scheme based on the kinetic flux-vector splitting (KFVS) method for the hyperbolic step, and a semi-implicit Runge-Kutta method for the relaxation step. The KFVS method is based on the direct splitting of macroscopic flux functions of the system on the cell interfaces. The second order accuracy of the scheme is achieved by using MUSCL-type initial reconstruction and Runge-Kutta time stepping method. Several case studies are considered. For validation, the results of current scheme are compared with those obtained from the splitting scheme based on the NT central scheme. The effects of various parameters such as device length, viscosities, different doping and voltage are analyzed. The accuracy, efficiency and simplicity of the proposed KFVS scheme validates its generic applicability to the given model equation.
关键词： Semiconductor devices,Kinetic flux vector,Viscous quantum hydro dynamical model
更新于2025-09-09 09:28:46
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Numerical investigation and experimental validation of an infrared measurement approach for surface heat flux distribution using a multi-color-reference
摘要： Accurate measurement of heat flux (HF) is significant in both industrial engineering and scientific research. It is acknowledged that the radiative HF can be easily determined by radiometers. In order to measure the conductive or convective HF distribution flowing across a surface, this paper presents a novel non-contact measuring method based on the infrared (IR) technique and inverse heat transfer method (IHTM). In addition, a specially designed multi-color-reference (MCR) which is composed of four sectors with four different known emissivity will be attached to the focused surface in the practical measurement. Therefore, different radiation signals among the four different sectors of MCR as well as the focused surface will be detected by an IR camera, through which a whole radiation temperature map can be obtained. Based on the differences in the radiation temperatures of the surface and MCR, the IHTM can be adopted to yield useful boundary conditions such as emissivity of the surface, convective heat transfer coefficient, and the critical HF distribution. The measuring method presented in this study combines the advantages of contact and non-contact measurement, which can accurately obtain the HF distribution under the difficult-contacted conditions such as the HF monitoring of a boiling furnace, HF estimating of the aerodynamic heating surface, etc. Numerical simulation and experimental verification were organized to justify the newly-developed measuring method. Relative error in the simulation is estimated to be less than 2%, and that in the experiment is calculated to be around 4.23%. The result displays a relatively high precision of the measuring method, demonstrating that such a method can be applied in practical application.
关键词： Infrared technique,Heat flux measurement,Emissivity,Heat transfer,IHTM
更新于2025-09-09 09:28:46
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Flux Region Assignment Method Using Ray Trace Information for the Method of Characteristics to Improve Cache Efficiency
摘要： A flux region assignment algorithm to increase cache efficiency for the method of characteristics (MOC) is proposed. In order to minimize the stride of memory access, flux region identifications are assigned based on the ray trace sequence during the MOC calculation. The present method is implemented in the three-dimensional transport code GENESIS and its performance is confirmed through verification calculations ranging from single pressurized water reactor (PWR) fuel assembly to PWR full-core benchmark problems. Quantitative comparison of cache efficiency is carried out and the present method shows improved cache efficiency, which results in a reduction in computation time. The present method can reduce computational time by improving cache efficiency while suppressing memory requirement.
关键词： GENESIS,flux region identifications,ray trace,Method of characteristics,cache
更新于2025-09-09 09:28:46
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Quantitative flux coupling analysis
摘要： Flux coupling analysis (FCA) aims to describe the functional dependencies among reactions in a metabolic network. Currently studied coupling relations are qualitative in the sense that they identify pairs of reactions for which the activity of one reaction necessitates the activity of the other one, but without giving any numerical bounds relating the possible activity rates. The potential applications of FCA are heavily investigated, however apart from some trivial cases there is no clue of what bottleneck in the metabolic network causes each dependency. In this article, we introduce a quantitative approach to the same ?ux coupling problem named quantitative ?ux coupling analysis (QFCA). It generalizes the current concepts as we show that all the qualitative information provided by FCA is readily available in the quantitative ?ux coupling equations of QFCA, without the need for any additional analysis. Moreover, we design a simple algorithm to ef?ciently identify these ?ux coupling equations which scales up to the genome-scale metabolic networks with thousands of reactions and metabolites in an effective way. Furthermore, this framework enables us to quantify the “strength” of the ?ux coupling relations. We also provide different biologically meaningful interpretations, including one which gives an intuitive certi?cate of precisely which metabolites in the network enforce each ?ux coupling relation. Eventually, we conclude by suggesting the probable application of QFCA to the metabolic gap-?lling problem, which we only begin to address here and is left for future research to further investigate.
关键词： Systems biology,FCA,Flux coupling analysis,Flux coupling equation,QFCA,Metabolic network analysis
更新于2025-09-04 15:30:14
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Transport Critical Current Density of Bi1.6Pb0.4Sr2Ca2Cu3O10)/Ag Superconductor Tapes with Addition of 50 and 70 nm MgO
摘要： added size 50 average particle and 70 nm were MgO nanoparticles with into Bi1.6Pb0.4Sr2Ca2Cu3O10(MgO)x/Ag superconductor tapes and sintered at 845 oC for 50 and 100 h. The effect of sintering time on the transport critical current density (Jc) was investigated. Jc of the tapes were measured in zero-field between 30 and 77 K and under magnetic fields at 77 K. The phase and microstructure of the tapes were examined by X-ray diffraction method and scanning electron microscopy, respectively. All tapes showed plate-like grains and a larger plate-like grain was observed in the tapes sintered for 100 h. Jc of the MgO added tapes was higher than those of the non-added tapes. Jc of the non-added tape sintered for 100 h was 10820 A/cm2 at 30 K and 1262 A/cm2 at 77 K. Jc of the tapes sintered for 100 h was higher than the tapes sintered for 50 h. The 50 nm MgO added tapes showed a higher Jc than the 70 nm MgO added tapes. Jc for the 100 h sintered MgO (50 nm) added tape was 22710 and 3070 A/cm2 at 30 and 77 K, respectively which are higher than that of the 100 h sintered MgO (70 nm) added tape. The improved Jc was attributed to the increase in flux pinning potential and improvement in the microstructure due to the addition of nano-sized MgO. This work showed the importance of the size of the added nanoparticles to the transport current properties of these superconductors.
关键词： flux pinning,transport critical current density,nano MgO,size effect
更新于2025-09-04 15:30:14