Multiscale Morphology Research Articles

Smooth Cascade of Wrinkles at the Edge of a Floating Elastic Film

An ultrathin polymer sheet floating on a fluid forms a periodic pattern of parallel wrinkles when subjected to uniaxial compression. The wave number of the wrinkle pattern increases sharply near the fluid meniscus where the translational symmetry of this one-dimensional corrugated profile is broken. We show that the observed multiscale morphology is controlled by a new "softness" number that quantifies the relative strength of capillary forces at the edge and the rigidity of the bulk pattern. We discover a new elastic cascade by which the wrinkling pattern in the bulk is smoothly matched to the fine structure at the edge by a discrete series of higher Fourier modes.

Multi-scale pore morphology in directed vapor deposited yttria-stabilized zirconia coatings

A high pressure, electron-beam directed-vapor deposition process has been used to deposit partially stabilized zirconia containing 7% mass yttria at deposition pressures of 7.5–23 Pa. Anisotropic, ultra-small-angle X-ray scattering (USAXS) was then used to determine the surface area, shape and orientation of pores within the coatings. The total surface area of the ellipsoidal shaped pores was found to increase with deposition pressure. However, the through-thickness thermal conductivity measurements reveal the existence of a minimum thermal conductivity in coatings deposited at an intermediate pressure. Observations of the anisotropic X-ray scattering intensity at this intermediate pressure indicated greater proportions of both feather-like (oblate) pores with their major dimension at about 60° to the plane of the coating and fine columnar (prolate) pores oriented perpendicular to the coating plane. Since these oblate pore orientations are most efficient at impeding conductive thermal transport through the coating, it is believed that the change in preferred pore orientations with pressure is responsible for the higher thermal resistance of coatings grown in the intermediate pressure regime.

Layered Distribution of Charge Carriers in Organic Thin Film Transistors

Drain-source current in organic thin-film transistors has been monitored in situ and in real time during the deposition of pentacene. The current starts to flow when percolation of the first monolayer (ML) occurs and, depending on the deposition rate, saturates at a coverage in the range 2-7 MLs. The number of active layers contributing to the current and the spatial distribution of charge carriers are modulated by the growth mode. The thickness of the accumulation layer, represented by an effective Debye length, scales as the morphological correlation length. These results show that the effective Debye length is not just a material parameter, but depends on the multiscale morphology. Earlier controversial results can be unified within this framework.

Multiscale Morphology of Organic Semiconductor Thin Films Controls the Adhesion and Viability of Human Neural Cells

We investigate how multiscale morphology of functional thin films affects the in vitro behavior of human neural astrocytoma 1321N1 cells. Pentacene thin film morphology is precisely controlled by means of the film thickness, Θ (here expressed in monolayers (ML)). Fluorescence and atomic force microscopy allow us to correlate the shape, adhesion, and proliferation of cells to the morphological properties of pentacene films controlled by saturated roughness, σ, correlation length, ξ, and fractal dimension, df. At early incubation times, cell adhesion exhibits a transition from higher to lower values at Θ ≈ 10 ML. This is explained using a model of conformal adhesion of the cell membrane onto the growing pentacene islands. From the model fitting of the data, we show that the cell explores the surface with a deformation of the membrane whose minimum curvature radius is 90 (± 45) nm. The transition in the adhesion at ∼10 ML arises from the saturation of ξ accompanied by the monotonic increase of σ, which leads to a progressive decrease of the pentacene local radius of curvature and hence to the surface area accessible to the cell. Cell proliferation is also enhanced for Θ < 10 ML, and the optimum morphology parameter ranges for cell deployment and growth are σ ≤ 6 nm, ξ > 500 nm, and df > 2.45. The characteristic time of cell proliferation is τ ≈ 10 ± 2 h.

Morphological Multiscale Enhancement, Fuzzy Filter and Watershed for Vascular Tree Extraction in Angiogram

This paper presented an automatic morphological method to extract a vascular tree using an angiogram. Under the assumption that vessels are connected in a local linear pattern in a noisy environment, the algorithm decomposes the vessel extraction problem into several consecutive morphological operators, aiming to characterize and distinguish different patterns on the angiogram: background, approximate vessel region and the boundary. It started with a contrast enhancement and background suppression process implemented by subtracting the background from the original angiogram. The background was estimated using multiscale morphology opening operators by varying the size of structuring element on each pixel. Subsequently, the algorithm simplified the enhanced angiogram with a combined fuzzy morphological opening operation, with linear rotating structuring element, in order to fit the vessel pattern. This filtering process was then followed by simply setting a threshold to produce approximate vessel region. Finally, the vessel boundaries were detected using watershed techniques with the obtained approximate vessel centerline, thinned result of the obtained vessel region, as prior marker for vessel structure. Experimental results using clinical digitized vascular angiogram and some comparative performance of the proposed algorithm were reported.

The Order Multi-scale Morphology Demodulation of the Vibration Signal of a Fault Gearbox with Rotating Speed Fluctuation

The order multi-scale morphology demodulation approach is proposed to extract the fault characteristic frequency from the vibration signal of a fault gearbox with rotating speed fluctuation. The chirplet path pursuit algorithm is used to obtain the rotation speed signal of the gearbox. According to the rotation speed signal,the time domain vibration signal of the gearbox is resampled at constant angle increments. An algorithm based on the information of local peaks of the signal is used to figure out the structuring elements for multiscale morphology analysis. The structuring elements are used to carry out morphology operations on the resampled signal. Spectral analysis on the average value of the operation results is carried out,so as to accomplish the order multi-scale morphology demodulation. Since the noise components do not correlate with the chirplet functions closely,the chirplet path pursuit algorithm can extract the rotation speed effectively even if the signal-to-noise ratio of the vibration signal is very low. By averaging the results of each scale morphology analysis,the multi-scale morphology demodulation can restrain the noise effectively. The proposed approach has good anti-noise ability,and is suitable for analyzing the actual vibration signal of a gearbox with rotating speed fluctuation. Simulation and practical application examples prove the validity and superiority of the proposed method.

Continuum of Structural Organization from Chitosan Solutions to Derived Physical Forms

The structural organization of chitosan, a cationic polyelectrolyte, in aqueous solutions of high ionic strength, is investigated by quasi-elastic light scattering and wet scanning transmission electron microscopy. The formation of submicrometric chain aggregates driven by hydrophobic interactions is evidenced. These heterogeneities are at the core of the multiscale morphology of physical hydrogels processed from this polysaccharide. Therefore, a close structural relationship exists between the initial solution and the final hydrogel.

QRS Detection Based on Multiscale Mathematical Morphology for Wearable ECG Devices in Body Area Networks

A novel wearable electrocardiograph (ECG) QRS detection algorithm for wearable ECG devices in body area networks is presented in this paper, which utilizes the multistage multiscale mathematical morphology filtering to suppress the impulsive noise and uses the multiframe differential modulus accumulation to remove the baseline drift and enhance the signal. The proposed algorithm, verified with data from the MIT/BIH Arrhythmia Database and wearable ECG devices, achieves an average QRS detection rate of 99.61%, a sensitivity of 99.81%, and a positive prediction of 99.80%. It compares favorably to the published methods.

Constructing Thin Polythiophene Film Composed of Aligned Lamellae via Controlled Solvent Vapor Treatment

Thin poly(3-butylthiophene) (P3BT) film composed of aligned lamellae attached to the edge of the original film has been achieved via a controlled solvent vapor treatment (C-SVT) method. The polarized optical microscopy operated at both single-polarization and cross-polarization modes has been used to investigate the alignment of the fiber-like lamellae. A numerical simulation method is used to quantitatively calculate angle distributions of the lamellae deviated from the film growth direction. Prepatterned P3BT film edge acts as nuclei which densely initialize subsequent crystal growth by exhausting the materials transported from the partially dissolved film. The growth of new film upon crystallization is actually a self-healing process where the two-dimensional geometric confinement is mainly responsible for this parallel alignment of P3BT crystals. The solvent vapor pressure should be carefully chosen so as to induce crystal growth but avoid liquid instability which will destroy the continuity of the film. The combination of microfabrication technique and C-SVT method provides a novel method to fabricate hierarchical structure within thin polymer film with multiscale morphology via utilizing both up-bottom and bottom-up approaches.

Effect of microstructural evolution on wettability of laser coated calcium phosphate on titanium alloy

Surface engineering of synthetic implant materials provides an exciting opportunity to mimic natural biomaterials. Surface that are bioactive and textured at multi-scale have the potential for easier osseointegration. Ti alloy surfaces known for their biocompatibility are coated with bioactive calcium phosphate using a laser source at multiple processing speeds. The resulting surface has multi-scale morphology and multi-phase chemical nature. Faster processing speeds showed improved wettability to water along with higher degree of crystallinity in the phases present. Furthermore, decreased laser processing speeds induced formation of increased amount of glassy phases that are expected to provide increased biocompatibility. The combination of these opposing effects suggested that optimum crystallinity leading to optimum wettability can be produced at intermediate speeds for improved biocompatibility.

Morphological enhancement of vascular angiogram with multiscale detected by Gabor filters

A multiscale morphology scheme for enhancing local contrast of a coronary angiogram is proposed. The method consists of a combined top-hat operator with structuring elements of different dimensions, which corresponds to the vessel diameter at each pixel point estimated by a group of Gabor wavelets under different orientation and scale. Experiment shows the results on a real angiogram.

Multiscale morphology analysis and its application to fault diagnosis

A novel approach to fault diagnosis is proposed using multiscale morphology analysis to extract impulsive features from the signals with strong background noise. Multiscale morphology is applied to one-dimensional signal by defining both the length and height scales of structuring elements (SEs). A local-peak-value based adaptive algorithm is also introduced. The new approach makes the selection of SEs more transparent and is independent of empirical rules. Both simulated impulsive and vibration signals of two defective roller bearings are employed to validate the proposed algorithm. The roller bearing faults presented in the validation include both inner and outer race faults. The test results show that the multiscale morphology analysis is effective and robust to extract morphological features.

Multiscale morphology of high-precision turning process surfaces

The characterization of functional surfaces is done mainly by roughness which can be quantified by many parameters. In order to select relevant roughness parameters, a multiscale discriminant method is proposed and applied to characterize high-precision turned surfaces. First, surfaces are characterized by a single roughness parameter and secondly by a pair of roughness parameters. In all cases, the most relevant evaluation length is also determined for each parameter. The results obtained on four different samples show that the most relevant roughness parameter is Rk estimated on a 10μm evaluation length. The best pair of parameters is Δa and Ri, estimated respectively on 20μm and 100μm evaluation lengths. Rk well characterizes the microroughness, which seems to be mainly representative of the roughness of high-precision machined surfaces. However, only multiscale analyses with a pair of roughness parameters can characterize both the macroscopic and microscopic morphologies of machined surfaces.

The multiscale morphology filter: identifying and extracting spatial patterns in the galaxy distribution

We present here a new method, MMF, for automatically segmenting cosmic structure into its basic components: clusters, filaments, and walls. Importantly, the segmentation is scale independent, so all structures are identified without prejudice as to their size or shape. The method is ideally suited for extracting catalogues of clusters, walls, and filaments from samples of galaxies in redshift surveys or from particles in cosmological N-body simulations: it makes no prior assumptions about the scale or shape of the structures.}

Adhesion and Proliferation of Fibroblasts on Cluster-Assembled Nanostructured Carbon Films: The Role of Surface Morphology

We have investigated the influence on adhesion and proliferation of NIH 3T3 fibroblasts of the surface morphology of cluster assembled carbon films deposited by Supersonic Cluster Beam Deposition. Nanostructured carbon films exhibit a multi-scale morphology, which resembles the surface structure of the extracellular matrix, and possess a high specific area, while being relatively smooth at all scales. Correlations between measured morphological parameters and adaptive cell response have been brought out. High specific area and smoothness appear to conceivably favour both the early attachment of plated cells and the long-term survival of adherent cells. Moreover, nano-structured carbon films affect the cells morphology as well as the extension and the number of the focal contacts.

Automatic diatom identification using contour analysis by morphological curvature scale spaces

A method for automatic identification of diatoms (single-celled algae with silica shells) based on extraction of features on the contour of the cells by multi-scale mathematical morphology is presented. After extracting the contour of the cell, it is smoothed adaptively, encoded using Freeman chain code, and converted into a curvature representation which is invariant under translation and scale change. A curvature scale space is built from these data, and the most important features are extracted from it by unsupervised cluster analysis. The resulting pattern vectors, which are also rotation-invariant, provide the input for automatic identification of diatoms by decision trees and k-nearest neighbor classifiers. The method is tested on two large sets of diatom images. The techniques used are applicable to other shapes besides diatoms.

Multiscale morphology and thermo‐mechanical history of poly(vinyl chloride) (PVC)

AbstractThe multiscale morphology of rigid poly(vinyl chloride) (PVC) formulations (in the nanometre to the micrometre range) was investigated by high resolution scanning electron microscopy, ultra‐small‐, small‐ and wide‐angle X‐ray scattering, as a function of thermo‐mechanical history. It has been shown that the hierarchical structure of PVC grains, when in the dry blend, disappeared during gelation that combines mechanical stress (ie shear stress and hydrostatic pressure) and heating. Nevertheless, the memory of the presence of the smallest particles (domains with diameters of about 80 nm) containing dense amorphous PVC and nanoscaled crystallites, has been highlighted by the study of the change of the microstructure when PVC was reprocessed with high mechanical deformation at a lower temperature than the previous gelation temperature. As a result, the main phenomena occurring during gelation were, in a first step, the disappearance of the hierarchical structure of the grains and, in a second step, the inter‐diffusion of the chains across the frontiers of the primary particles (mechanically reversible), but maintaining the domain structure. The crystalline microstructure was affected by thermo‐mechanical history, but the gelation level should not be estimated strictly in relation to the crystalline morphology. Copyright © 2004 Society of Chemical Industry

Digital Image-based Analysis of Morphology for Porous Materials

The porous material is one of the promising functional materials, and its macroscopic properties are strongly dependent on the microscopic morphology. To study the correlation between the microscopic heterogeneity and the macroscopic properties, a novel digital imagebased analysis methodology is proposed in this paper, which consists of high resolution X-ray CT, digital image-based modeling, multi-scale stress analysis and geometrical morphology analysis. The proposed morphology analysis enables us to predict the microscopic stress concentration for spherical porous ceramics considering the heterogeneous dispersion of spherical pores and the macroscopic loading condition. The heterogeneity can be analyzed geometrically for very huge data with approximately 58 million voxel elements quickly. The morphology analysis is helpful for the multi-scale modeling and microscopic stress evaluation. The microscopic stress distribution is also discussed in association with the random heterogeneity for ceramics with open pores and with high porosity ratios.

SUS304鋼疲労き裂近傍における塑性誘起マルテンサイト変態のマルチスケール解析(S07-1 先端材料I,S07 メゾスケールにおける先進材料の力学と強度・機能評価)

SUS304鋼疲労き裂近傍における塑性誘起マルテンサイト変態のマルチスケール解析(S07-1 先端材料I,S07 メゾスケールにおける先進材料の力学と強度・機能評価)

Multiscale morphological segmentation of gray-scale images

In this paper, the authors have proposed a method of segmenting gray level images using multiscale morphology. The approach resembles the watershed algorithm in the sense that the dark (respectively bright) features which are basically canyons (respectively mountains) on the surface topography of the gray level image are gradually filled (respectively clipped) using multiscale morphological closing (respectively opening) by reconstruction with isotropic structuring element. The algorithm detects valid segments at each scale using three criteria namely growing, merging and saturation. Segments extracted at various scales are integrated in the final result. The algorithm is composed of two passes preceded by a preprocessing step for simplifying small scale details of the image that might cause over-segmentation. In the first pass feature images at various scales are extracted and kept in respective level of morphological towers. In the second pass, potential features contributing to the formation of segments at various scales are detected. Finally the algorithm traces the contours of all such contributing features at various scales. The scheme after its implementation is executed on a set of test images (synthetic as well as real) and the results are compared with those of few other standard methods. A quantitative measure of performance is also formulated for comparing the methods.