Spatially Resolved Stress Measurements in Materials With Polarisation-Sensitive Optical Coherence Tomography: Image Acquisition and Processing Aspects

Abstract:  We demonstrate that polarisation-sensitive optical coherence tomography (PS-OCT) is suitable for mapping the stress distribution within materials in a contact-free and non-destructive way. In contrast to transmission photoelasticity measurements, the samples do not have to be transparent but can be of scattering nature. Denoising and analysis of fringe patterns in single PS-OCT retardation images are demonstrated to be the bases for a quantitative whole-field evaluation of the internal stress state of samples under investigation.     

Isolation and characterization of pepsin‐solubilized collagen from the integument of sea cucumber (Stichopus vastus)

BACKGROUND: Sea cucumber (Stichopus vastus) is considered an underutilized resource, since only its stomach and intestines are eaten raw as salad in a few countries and the remaining parts, especially the integument rich in collagen, is discarded. Hence a valuable by‐product having potential nutraceutical and pharmaceutical applications is wasted. In the present investigation, pepsin‐solubilized collagen (PSC) from the integument of S. vastus was isolated, purified and characterized. RESULTS: Sodium dodecyl sulfate–polyacrylamide gel electrophoretic analysis showed that the purified collagen was of type I, consisting of three α1 chains of approximately 122 kDa each. The peptide map of PSC digested by V8 protease was different from that of calf skin type I collagen. Fourier transform infrared spectroscopy revealed that the triple helical structure was well preserved in isolated collagen. The denaturation temperature of PSC was 21.23 °C and showed good gel‐forming capability at pH 6.5 and 300 mmol L^?1 NaCl. CONCLUSION: It is inferred that the collagen isolated from S. vastus integument has potential for use as an alternative to land‐based mammalian collagen in food, nutraceuticals and pharmaceutical industries. © 2012 Society of Chemical Industry     

Carpet cloak from optical conformal mapping

The original carpet cloak was designed by a numerical method, the quasi-conformal mapping. There- fore its refractive index profile was obtained numerically. In this letter, we propose a new carpet cloak based on the optical conformal mapping, with an analytical form of a refractive index profile, thereby facilitating future experimental designs.     

一致L—Lipschitzian非自映象不动点的迭代逼近

在实Banach空间中，研究迭代序列xn＋1=P 在对参数适当限制条件下逼近一致L—Lipschitzian非自映象的不动点问题．     

Volumetric colon wall unfolding using harmonic differentials

Volumetric colon wall unfolding is a novel method for virtual colon analysis and visualization with valuable applications in virtual colonoscopy (VC) and computer-aided detection (CAD) systems. A volumetrically unfolded colon enables doctors to visualize the entire colon structure without occlusions due to haustral folds, and is critical for performing efficient and accurate texture analysis on the volumetric colon wall. Though conventional colon surface flattening has been employed for these uses, volumetric colon unfolding offers the advantages of providing the needed quantities of information with needed accuracy. This work presents an efficient and effective volumetric colon unfolding method based on harmonic differentials. The colon volumes are reconstructed from CT images and are represented as tetrahedral meshes. Three harmonic 1-forms, which are linearly independent everywhere, are computed on the tetrahedral mesh. Through integration of the harmonic 1-forms, the colon volume is mapped periodically to a canonical cuboid. The method presented is automatic, simple, and practical. Experimental results are reported to show the performance of the algorithm on real medical datasets. Though applied here specifically to the colon, the method is general and can be generalized for other volumes.     

Spatial and temporal dynamics of river channel migration and vegetation in central Amazonian white-water floodplains by remote-sensing techniques

We investigated spatial and temporal migration of the Solimões, the Japurá, and the Aranapu River channels in western Brazilian Amazonia with Landsat TM imagery over a 21-year period. Additionally, we classified and monitored how channel migrations affect the distribution of pioneer vegetation and old-growth forest. The cloud-free study area was 153,032 ha — open water plus 3 km inland on each margin. The channel migration rates, expressed as percent dislocation of the open water body of the river year^− 1, were lowest in the Japurá River (1.2%), and highest in the Aranapu channel (2.5%), the point bars at river confluence being the most affected landforms subject to geomorphic changes. Annual rates of lateral erosion and accretion of vegetated land along the three rivers were well-balanced. They averaged 0.79 and 0.83% of the cloud-free channel area over the 21 years. The Solimões River was more dynamic than the Japurá River, which can be traced to higher water discharge and sediment load. During the 21 years, the area covered by pioneer vegetation increased by 5.8% of the study area, while late-succession areas decreased by a similar amount (5.5%). According to local biomass estimates of the different vegetation types, these values suggest that C-releases by alluvial erosion would be much higher than C-sequestration caused by the creation of areas suitable for colonization by pioneer vegetation at our study site.     

General Mandelbrot sets and Julia sets with color symmetry from equivariant mappings of the modular group

A method for constructing the general M (Mandelbrot) set of a non-analytic mapping is presented. The equivariant mapping with symmetry of the modular group is considered as an illustration. By investigating the distribution of attractors in the upper half-plane and the assignment of colors to each attractor, an algorithm is presented for the construction of filled-in Julia sets with 2- or 3-color symmetry. Such Julia sets not only reveal the characteristics of a system, but also have high artistic appeal.     

GENERALIZED THRESHOLD DECOMPOSITION

This paper develops a powerful technique called threshold decomposition which is introduced for the analysis and implementation of median filter. This technique called generalized decomposition(GTD) is better than the original method in the theoretical analysis and VLSI realization.     

机载激光水深测量精度分析

分析了机载激光水深测量系统中的深度反演方法，着重讨论波浪潮汐改正法和利用动态全球定位系统-相位模糊度解算技术(KGPS-OTF)所测参量进行归算的方法(无修正法)。综合分析影响机载激光测深精度的各项参量，并利用机载激光雷达的技术参数，定量估算了两种方法的水深提取精度。结果表明，波浪潮汐改正法的精度略高于无修正法，但是无修正方法更加简单明了，数据后处理的计算量也可大大减小。