共查询到12条相似文献,搜索用时 15 毫秒
1.
In this article, we proposed a new method based on natural neighbor interpolation to recover the spectral reflectance of objects from an image captured by a traditional Red‐Green‐Blue (RGB) digital camera. The concept of model‐based metameric spectra of eight extreme points in the standard RGB (sRGB) color gamut was further introduced to ensure that almost all test samples in the entire gamut can be simply and properly recovered without needing the extrapolation or any other auxiliary techniques. The quasi‐Newton method was used to estimate iteratively the optimal parameters of these metameric spectra, satisfying the constraints of the gamut extreme points. Several experiments were performed. The effectiveness of the method with and without the metameric spectra was evaluated, including some performance comparisons with the principal component analysis (PCA) method of transformational type (classic PCA and weighted PCA) and that of interpolation type. The results showed that the proposed method greatly enlarged the accurately applicable domain of the interpolation strategy and offered spectra with feasibility and naturalness much superior to the PCA‐based methods. The proposed method was obviously better than the conventional interpolation ones, and had a similar performance with the weighted PCA method in terms of color difference. 相似文献
2.
Alamin Mansouri Tadeusz Sliwa Jon Y. Hardeberg Yvon Voisin 《Color research and application》2008,33(6):485-493
In this article, we deal with the problem of spectral reflectance function representation and estimation in the context of multispectral imaging. Because the reconstruction of such functions is an inverse problem, slight variations in input data completely skew the expected results. Therefore, stabilizing the reconstruction process is necessary. To do this, we propose to use wavelets as basis functions, and we compare those with Fourier and PCA bases. We present the idea and compare these three methods, which belong to the class of linear models. The PCA method is training‐set dependent and confirms its robustness when applied to reflectance estimation of the training sets. Fourier and wavelet bases allow good generalization; an advantage of wavelets is that they avoid boundary artifacts. The results are evaluated with the commonly used goodness‐of‐fit coefficient (GFC), and the reliability of the use of wavelets is proved. © 2008 Wiley Periodicals, Inc. Col Res Appl, 33, 485–493, 2008 相似文献
3.
Ruben C. Pastilha Joo M.M. Linhares Ana I.C. Rodrigues Srgio M.C. Nascimento 《Color research and application》2019,44(3):411-418
The Munsell Color System and the Natural Color System are widely used but they have some limitations due to the manufacturing process and sampling choices. To estimate quantitatively these limitations we compared the colors of natural scenes with the colors represented by these systems under a wide range of illuminants. Spectral data from the two systems and from natural scenes were used in the analysis. It was found that a considerable portion of natural colors are not accounted by these systems, mainly colors with low lightness levels. Under D65 the Munsell Color System color volume corresponds to 72% of the Natural Color System color volume which in turn represents only 53% of the natural scenes color volume. If individual colors are considered, less than half are contained within these systems. To obtain a complete match to the natural colors contained by the color systems thresholds of 7 and 5 CIELAB units would be required for Munsell Color System and Natural Color System, respectively. Variations with the illuminant are generally modest showing that both system work similarly across different illuminations. Although these Color Systems have limitations in describing low lightness colors they perform quite well for medium to high levels of lightness. 相似文献
4.
Duck Bong Kim In Yeop Jang Han Kyun Choi Kwan H. Lee 《Color research and application》2016,41(4):358-371
A spectral‐based method can acquire and represent the surface appearance of a given material physically correctly. But, it has drawbacks due to its high measurement cost and a long computation time in measuring, modeling, and rendering. In this article, we present spectral recovery and representation of spectral bidirectional reflectance distribution function (BRDF) from multispectral reflectance measurements in which we can render real appearance materials over a 3D model with accuracy and efficiency. First of all, an accurate spectral BRDF recovery algorithm, which transforms multispectral high dynamic range images into highly dense BRDFs in both a spectral and an angular domain, is proposed. Second, an efficient representation method is developed representing spectral BRDFs compactly using a factorization method and an adaptive spectral sampling method that uses a given error bound. The results show that the proposed method can compress the spectral BRDF data down by several hundred times while maintaining the given accuracy in colorimetric and spectral domains under a specific illuminant. © 2015 Wiley Periodicals, Inc. Col Res Appl, 41, 358–371, 2016 相似文献
5.
We propose an algorithm for parameter estimation in nonlinear chemical and biological stochastic processes with unmeasured variables and small data sets. The algorithm relies on an iterative approach wherein random samples of parameters and unmeasured variables are generated, from their respective posterior density functions, through Markov chain Monte Carlo simulations. The random samples are then used in approximating the posterior density functions of the parameters. The effectiveness of the algorithm is demonstrated through two biological examples—a feed-forward loop genetic regulatory network and a JAK–STAT signal transduction pathway. 相似文献
6.
Shujuan SUN Lei WANG Suiliang HUANG Teng TU Hongwen SUN 《Frontiers of Chemical Science and Engineering》2011,5(3):308
A microcosm system that included river sediment, water and different zeolite capping materials (natural zeolite, surfactant-modified zeolite (SMZ), or aluminum modified zeolite (AMZ)) was designed to study the effect of capping on the release of phosphorus and three organic pollutants (phenol, pyridine, and pyrene) from the sediment to the overlying water over the course of three month. For the same amount of the three capping materials, the efficiency of phosphorus inactivation was in the order of SMZ>AMZ>natural zeolite. The inactivation of phosphorus was mainly caused by the covering effect, co-precipitation and adsorption by the capping materials. The different zeolites gave different results for the release of phenol, pyridine, and pyrene from the sediment. When natural zeolite was used as the capping material, there was no effect on the release of pyrene and pyridine, whereas capping the sediment with SMZ or AMZ inhibited the release of pyrene and pyridine but to different extents. However, for controlling the release of phenol from the sediment, aluminum modified zeolite was the most efficient material, whereas no effects were observed when natural zeolite or SMZ were used. The different capabilities of the zeolite materials for controlling the release of different organic pollutants are related to the differences in the electrical properties of these pollutants. 相似文献
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Punyarat Jantachum Sumalin Phokha Sitchai Hunpratub Narong Chanlek Songkot Utara 《应用聚合物科学杂志》2024,141(8):e54969
In this study, cerium oxide nanoparticles (nanoceria, CeNP) were used as a nanofiller in epoxidized natural rubber with varying epoxide levels, including 25% epoxidation (ENR-25) and 50% epoxidation (ENR-50). Co-precipitation methods were employed to synthesize a pure phase of CeNP with an average particle size of 11.4 ± 2.0 nm. CeNP was characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy. The effect of CeNP loading with 0–3 parts per hundreds of rubber (phr) on the properties of rubber nanocomposites was explored. ENR-25 nanocomposites with 1 phr of CeNP exhibited higher tensile strength and elongation at break compared to ENR-50 nanocomposites. These findings correspond to a lower Payne effect, improved scorch safety, and better processability. The strongest and most effective CeO2–ENR interactions via silane linkages are expected to outperform sulfur crosslinking in ENR-25 having 1 phr of CeNP. Microstructural evaluation of an ENR-25 sample containing 1 phr of CeNP indicated well-distributed nanofillers in the ENR-25 matrix, indicating that CeNP and ENR-25 appeared to be well-matched. Hardness of all ENR nanocomposites increased with CeNP loading. The cracking resistance, creep properties, and thermal stability of rubber nanocomposites were unaffected by addition of CeNP in the ENR-25 and ENR-50 samples. 相似文献
9.
Suisui Zhang Gang Li Boyang Bai Luyao Qiang Xiaoxun Ma Jingying Li 《Frontiers of Chemical Science and Engineering》2022,16(12):1713
China is the largest producer and consumer of HFC-134a (1,1,1,2-tetrafluoroethane) in the world. Coal-based route is mainly adopted to produce HFC-134a, which suffers from large waste and CO2 emissions. Natural gas is a low-carbon and clean energy resource, and no research has been found on the environment and economy of producing HFC-134a from natural gas. In this study, CML 2001 method was used to carry out the life cycle assessment of natural gas (partial oxidation)-based and natural gas (plasma cracking)-based routes (abbreviated as gas(O)-based and gas(P)-based routes, respectively), and their environmental performances were compared with coal-based and oil-based routes. Meanwhile, considering that China is vigorously promoting the transformation of energy structure, and the application of electric heating equipment to replace fossil-based heating equipment in industrial field, which has a great impact on the environmental performance of the production processes, the authors conducted a scenario analysis. The results showed that the gas(O)-based route had the most favourable environmental benefits. However, the gas(P)-based route had the highest potential for reducing environmental burdens, and its environmental benefit was the most favourable in scenario 2050. Additionally, the economic performance of the gas(P)-based route was significantly better than that of gas(O)-based and coal-based routes. 相似文献
10.
Hybrid transdermal drug delivery patch made from poly(p‐phenylene vinylene)/natural rubber latex and controlled by an electric field 下载免费PDF全文
A flexible, natural rubber (NR) patch was developed for electrically controllable transdermal drug delivery. NR latex was crosslinked at various crosslinking ratios under the UV curing method. Ibuprofen (Ibu) was the model drug and was used as the dopant for poly(p‐phenylene vinylene) (PPV) acting as the drug encapsulating host. For the pristine Ibu‐loaded NR patch, the amount of Ibu permeation increased with decreasing crosslink density and increasing electrical potential. For the Ibu‐doped PPV/NR patch, the amount of Ibu release?permeation also increased with increasing electrical potential and was higher than that of the pristine NR matrices. Without an applied electric field, the drug remained attached to the PPV during an initial period of 6 h. Under an applied electric field, the oxidation state of the conductive polymer was altered, the iontophoretic effect, pore formation in the NR matrix, expansion of the pore size in hair follicles and PPV chain expansion combined to increase the Ibu release?permeation amount. Thus, the flexible PPV/NR transdermal drug delivery patch was demonstrated to be effective in drug release?permeation based on the strength of the electrical potential, the crosslinking density and the presence of PPV as the encapsulation host. © 2018 Society of Chemical Industry 相似文献
11.
Effect of ship tilting and motion on amine absorber with structured‐packing for CO2 removal from natural gas 下载免费PDF全文
Dung Anh Pham Young‐Il Lim Hyunwoo Jee Euisub Ahn Yongwon Jung 《American Institute of Chemical Engineers》2015,61(12):4412-4425
A gas‐liquid Eulerian porous media computational fluid dynamics (CFD) model was developed for an absorber with structured packing to remove CO2 from natural gas by mono‐ethanol‐amine (MEA). The three‐dimensional geometry of the amine absorber with Mellapak 500.X was constructed to investigate the effect of the tilting and motion experienced on ships and barges for offshore plants. The momentum equation included porous resistance, gas‐liquid momentum exchange, and liquid dispersion to replace structured‐packing by porous media. The mass equation involved mass transfer of CO2 gas into MEA solution, and one chemical reaction. Parameters of the CFD model were adjusted to fit experimental data measured in the CO2‐MEA system. As the tilting angle increased, the liquid holdup and effective interfacial area decreased and CO2 removal efficiency was lowered. The uniformity of liquid holdup deteriorated by 10% for a 3° static tilting, and a rolling motion with 4.5° amplitude and 12 s period, respectively. © 2015 American Institute of Chemical Engineers AIChE J, 61: 4412–4425, 2015 相似文献
12.
Being polar and compatible with poly(vinyl chloride), epoxidized natural rubber (ENR) is similar in behaviour to acrylonitrile butadiene rubber (NBR). To assess the extent of this similarity, the mechanical properties of 50/50 blends of PVC with these two rubbers were compared. Their response to thermo-oxidative ageing in the presence of an antioxidant and a base was also investigated by ageing the blends at 100°C for 7 days. Studies involving mechanical properties and FTIR were used to evaluate the extent of thermal degradation. The results revealed that blends of ENR show mechanical properties which are as good as, and in some instances better than, those of the NBR blends. However, the ENR blends with PVC are very prone to oxidative ageing. This might be attributed to the susceptibility of the oxirane group to ring-opening reactions, particularly in the presence of PVC, which yields HCl as it degrades. The amine-type antioxidant 2,24-trimethyl-1,2-dihydroquinoline (TMQ) improved the oxidative stability of both blends. This was more significant in the ENR blend, which in some cases attained stability comparable with that of NBR. The addition of a base, calcium stearate [Ca(St)2], did not show any influence in the PVC/ENR blend, even though it was expected to curb acid-catalysed degradation. Ca(St)2, however, improved the oxidative stability of the PVC/NBR blend. The combination of optimum amounts of TMQ and Ca(St)2 effectively improved the tensile strength of both unaged blends, without appreciable adverse effect on elongation at break. This combination also imparted stability better than that of TMQ alone. 相似文献