Efficient pan-sharpening of satellite images with the contourlet transform

Recent studies show that hybrid panchromatic sharpening (pan-sharpening) methods using the non-sub-sampled contourlet transform (NSCT) and classical pan-sharpening methods such as intensity, hue and saturation (IHS), principal component analysis (PCA), and adaptive principal component analysis (APCA) reduce spectral distortion in pan-sharpened images. The NSCT is a shift-invariant multi-resolution decomposition. It is based on non-sub-sampled pyramid (NSP) decomposition and non-sub-sampled directional filter banks (NSDFBs). We compare the performance of the APCA–NSCT using different NSP filters, NSDFB filters, number of decomposition levels, and number of orientations in each level on SPOT 4 data with a spatial resolution ratio of 1:2, and Quickbird data with a spatial resolution ratio of 1:4. Experimental results show that the quality of pan-sharpening of remote-sensing images of different spatial resolution ratios using the APCA–NSCT method is affected by NSCT parameters. For the NSP, the ‘maxflat’ filters have the best quality, while the ‘sk’ filters give the best quality for the NSDFB. Changing the number of orientations at the same level of decomposition in the NSCT has a small effect on both the spectral and spatial qualities. The spectral and spatial qualities of pan-sharpened images mainly depend on the number of decomposition levels. Too few decomposition levels result in poor spatial quality, while excessive levels of decomposition result in poor spectral quality. Two levels of decomposition in the case of SPOT 4 data with a spatial resolution ratio of 1:2 achieve the best results. Also, three levels of decomposition in the case of QuickBird data with a spatial resolution ratio of 1:4 show the best results.     

Variational formulation of hyperbolic heat conduction problems applying Laplace transform technique

In this paper, a non-Fourier heat conduction problem is analyzed by employing newly developed theory. Application of conventional numerical schemes leads to strong oscillations of the results around discontinuities in solution domain. To overcome this difficulty the variational formulation of the Laplace-transformed hyperbolic heat conduction equation is developed. The results were used for evaluation of parameters used in approximate transformed temperature profiles. To validate the approach the results were compared with the exact analytical solution solved at special case and with an approach previously reported in the literature. Both showed a close agreement with the proposed approach.     

Mechanical and physical characterization of copper foam

A lost carbonate sintering process in powder metallurgy has been used to prepare copper foam of low to medium porosities with controlled pore size, shape, and distribution. The compressive properties of the copper foams have been investigated for different metal volume fractions ranging from 15–100%. The elastic moduli measurements in good agreement with Mori-Tanaka predictions for the two-phase mixtures. The microstructure, the electrical resistivity, and the thermal conductivity were also studied.     

Formation Kinetics of Monomeric Cyclic Fatty Acid Methyl Esters of Alpha-Linolenic Acid: Effects of Mono cis/trans Isomers

Cyclic fatty acid monomers (CFAM) are formed at low levels in edible oils during thermal processing operations such as frying or refining, and inevitably become part of the diet. These proatherogenic agents may increase the levels of oxidative stress markers, and induce hepatomegaly and steatosis. However, the kinetics involved in their formation is not well known. The objective of the present study was to evaluate the effects of cis and trans isomers on cyclization reactions involved in the thermal transformation of alpha-linolenic acid (ALA). Geometrical isomers of ALA were obtained from all-cis ALA by nitric acid treatment. Mono-trans isomers were concentrated using silver nitrate-silica gel chromatography. All-cis ALA, isomerized ALA, and a fraction at 85% mono-trans isomers were heat treated at 275 °C in hexadecane for periods up to 24 hours, and the formation of geometrical isomers and CFAM was monitored by GC. The results show that mono-trans isomers at carbon 9 and carbon 15 form CFAM at an accelerated rate, compared to the corresponding cis isomers, resulting in the formation of higher levels of CFAM over shorter time periods. The validation of the kinetic model was performed by solving simultaneously and nonlinearly fitting the system of coupled differential equations with experimental data. Good agreement was found between the experimental data and the predicted values. This work suggests that the use of polyunsaturated vegetable oils over extended periods for thermal processing of food may result in the formation of CFAM, in particular, if mono-trans isomers are present in the oil.     

Natural convection heat transfer in a partially opened cavity filled with porous media

This paper examines the steady natural convection in a partially opened enclosure filled with porous media using the Brinkman–Forchheimer model. Whilst the part of the left vertical wall of the cavity is heated, the other walls are adiabatic or thermally insulated Based upon numerical predictions, the effects of pertinent parameters such as Grashof number, Darcy number, porosity, length of the heated wall and the location center of the opened cavity are examined. It is found that as the Grashof number increases, due to strengthening buoyancy driven flows, the local Nusselt number from partially heated vertical wall, at a given position on this wall increases. This, in turn, increases the temperature of the heated wall. The results of this study can be used in the design of an effective cooling system for electronic components to help ensure effective and safe operational conditions.     

鲁卜哈利盆地B区块近地表快速建模研究与应用

沙特阿拉伯鲁卜哈利盆地B区块地表多为沙丘、戈壁，近地表地质条件复杂，横向速度变化大，静校正问题严重。B区块勘探程度低，微测井数量少，原有的近地表模型不能很好地解决资料处理中的静校正问题，给最终的处理结果带来影响。针对这一问题，在充分考虑油气勘探对数据处理的精度要求和时效性基础上，探讨了B区块近地表建模的难点，提出了一种快速近地表模型建立方法。首先将B区块划分为沙丘、戈壁和沙丘一戈壁过渡带等不同类型的近地表区域；然后根据划分结果分别采用不同的建模方法，对沙丘底面进行准确定义，对微测井空白区带的速度误差进行校正，将沙丘压实曲线应用到模型的建立中，最终获得了能准确描述B区块近地表介质特征的模型，解决了原模型在近地表速度变化区（带）、微测井空白区（带）描述中存在的问题。利用新建立的近地表模型对二维、三维地震资料进行了处理，得到了品质较好的叠加剖面。     

Dielectric relaxation analysis of biopolymer poly(3‐hydroxybutyrate)

Poly(3‐hydroxybutyrate), PHB, is a widely distributed carbon storage polymer among prokaryotes including Rhizobium. Capacities of Rhizobium etli R13 to produce the bioplastic during growth on media with different carbon sources appeared to be specific carbon‐source. In fed batch fermentation, R. etli R13 resulted in cell dry weight 6.2 g/L and PHB 51.4%. Gas chromatography‐mass spectrometry and gel permeation chromatography analysis revealed that PHB produced from R. etli R13 was solely composed of 3‐hydroxybutyric acid and the molecular mass of the purified PHB was 3.4 × 10⁵ Da with polydispersity 1.47. Dielectric relaxation of PHB has been studied in the temperature and frequency ranges 300–440 K and 10 kHz–4 MHz, respectively. A clear dielectric α and ρ‐relaxation processes are observed in these studied ranges of temperature and frequency. The first process is due to the dipole relaxation in the crystalline phase of PHB. The second one is due to the space‐charge formation or Maxwell‐Wagner‐polarization. The α‐relaxation process has been investigated by semiempirical Havriliak‐Negami relaxation function. The activation energy (E_a) and the relaxation time (τ₀) are calculated using the Arrhenius equation. The dielectric relaxation strength (Δε) is strongly temperature dependent. The calculated values of E_a for ac conductivity, ln(σ), of PHB provide information about the presence of electronic conduction. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Thermogravimetric analysis and dynamic Young's modulus measurement of N,N‐dimethylacetamide‐impregnated wood polymer composites

Mercerized wood species were impregnated with N,N‐dimethylacetamide. Their Fourier transform infrared spectra then showed enhanced absorption at 1419 cm^?1 (? C? /CH3), and the 1267‐cm^?1 (? N? /CH3) stretching band confirmed the occurrence of a modification reaction. Thermogravimetric investigation of the resultant wood polymer composites (WPCs) indicated a better thermal stability in comparison with that of the raw wood. The dynamic Young's modulus of the WPCs was significantly increased compared with that of raw wood. After modification, analysis by scanning electron microscopy showed porous cells of raw wood filled with the polymer, which led to the better stability of WPCs. Analysis by XRD indicated that the crystallinity of WPCs increased because of an increase in the stiffness and the thermal stability of the composites. J. VINYL ADDIT. TECHNOL., 2011. © 2011 Society of Plastics Engineers