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Search Results: 1 - 10 of 10761 matches for " Claudia Redenbach "
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ON THE DILATED FACETS OF A POISSON-VORONOI TESSELLATION
Claudia Redenbach
Image Analysis and Stereology , 2011, DOI: 10.5566/ias.v30.p31-38
Abstract: In this paper, the parallel set ΞR of the facets ((d 1)-faces) of a stationary Poisson-Voronoi tessellation in 2 and 3 is investigated. An analytical formula for the spherical contact distribution function of the tessellation allows for the derivation of formulae for the volume density and the specific surface area of ΞR. The densities of the remaining intrinsic volumes are studied by simulation. The results are used for fitting a dilated Poisson-Voronoi tessellation to the microstructure of a closed-cell foam.
STATISTICAL ANALYSIS OF THE LOCAL STRUT THICKNESS OF OPEN CELL FOAMS
André Liebscher,Claudia Redenbach
Image Analysis and Stereology , 2013, DOI: 10.5566/ias.v32.p1-12
Abstract: Open cell foams are formed by an interconnected network of struts whose thickness varies locally. These variations were shown to have an impact on the elastic and thermal properties of the foam. In this paper we quantify the local strut thickness by means of micro computed tomography (μCT) imaging. We introduce a skeletonization based topological decomposition of the foam structure into its vertices and struts. This allows to estimate the thickness of individual strut segments by the Euclidean distance transform, where an appropriate correction for struts with nonspherical cross-sectional shape is applied. Conflating these estimates based on the strut lengths results in a strut thickness profile for the entire foam. Polynomial models for the strut thickness profile are investigated by means of a regression analysis.
On the arrangement of cells in planar STIT and Poisson line tessellations
Claudia Redenbach,Christoph Thaele
Statistics , 2011,
Abstract: It is well known that the distributions of the interiors of the typical cell of a Poisson line tessellation and a STIT tessellation with the same parameters coincide. In this paper, differences in the arrangement of the cells in these two tessellation models are investigated. In particular, characteristics of the set of cells neighbouring the typical cell are studied. Furthermore, the pair-correlation function and several mark correlation functions of the point processes of cell centres are estimated and compared.
MESH FREE ESTIMATION OF THE STRUCTURE MODEL INDEX
Joachim Ohser,Claudia Redenbach,Katja Schladitz
Image Analysis and Stereology , 2009, DOI: 10.5566/ias.v28.p179-185
Abstract: The structure model index (SMI) is a means of subsuming the topology of a homogeneous random closed set under just one number, similar to the isoperimetric shape factors used for compact sets. Originally, the SMI is defined as a function of volume fraction, specific surface area and first derivative of the specific surface area, where the derivative is defined and computed using a surface meshing. The generalised Steiner formula yields however a derivative of the specific surface area that is – up to a constant – the density of the integral of mean curvature. Consequently, an SMI can be defined without referring to a discretisation and it can be estimated from 3D image data without need to mesh the surface but using the number of occurrences of 2×2×2 pixel configurations, only. Obviously, it is impossible to completely describe a random closed set by one number. In this paper, Boolean models of balls and infinite straight cylinders serve as cautionary examples pointing out the limitations of the SMI. Nevertheless, shape factors like the SMI can be valuable tools for comparing similar structures. This is illustrated on real microstructures of ice, foams, and paper.
Asymptotic shape of small cells
Mareen Beermann,Claudia Redenbach,Christoph Thaele
Statistics , 2012,
Abstract: A stationary Poisson line tessellation is considered whose directional distribution is concentrated on two different atoms with some positive weights. The shape of the typical cell of such a tessellation is studied when its area or its perimeter tends to zero. In contrast to known results where the area or the perimeter tends to infinity, it is shown that the asymptotic shape of cells having small area is degenerate. Again in contrast to the case of large cells, the asymptotic shape of cells with small perimeter is not uniquely determined. The results are accompanied by a large scale simulation study.
Learning from experience: A simple effective protocol to test footwear prescriptions for the Diabetic foot by using the Pedar system  [PDF]
Claudia Giacomozzi, Luigi Uccioli
Journal of Biomedical Science and Engineering (JBiSE) , 2013, DOI: 10.4236/jbise.2013.65A008
Abstract:

Adherence of patients to treatment and appropriateness of prescribed footwear are mandatory for successful prevention of Diabetic foot ulceration. In a Public Healthcare Service, footwear approval is under the responsibility of the clinician. In some cases kinetic measurements are taken inside the shoes to support the clinical decision; however, an overall agreement is still missing with respect to a simple, reliable and effective test protocol based on proper threshold values. Authors’ past experiences, specific needs of the Diabetic outpatient service, and suggestions from valuable literature led to an instrumental test protocol based on reference peak pressure (PP) thresholds and gait line (GL) specific for each level of risk. Permission was obtained for one preliminary validation session at the Authors’ outpatient service, during which 11 patients at high/very high risk of ulceration were examined—9 for testing new footwear, 2 for monitoring 12-month-old footwear. The protocol was well accepted by patients and operators, fast and easy to be used. Based on the instrumental, clinical and visual inspection data; 4 new footwear did not pass the test; 5 passed the test but integration or minor changes were requested; the 2 old footwear were found no more effective. As a first positive feedback, after 4 months of wearing the modified prescriptions none of the patients had developed plantar ulcers or signs of tissue damage. Successive data processing proved that in all patients altered PPs and deviated GLs did correlate with alterations of other kinetic parameters. The protocol, which is proved to be sensitive and valuable for the Diabetic foot care, may have a general validity; the delivered specific PP thresholds and reference data, instead, can be reliably used if the test is performed with a calibrated Pedar Insole System and with the wide Insoles in the range UW-YW (EU size 36 - 45).

Simulated Sample Behaviour of a Dissimilarity Index When Sampling from Populations Differing by a Location Parameter Only  [PDF]
Fabio Manca, Claudia Marin
Applied Mathematics (AM) , 2014, DOI: 10.4236/am.2014.515213
Abstract: In this paper the authors study empirically the power of the test based on the index of dissimilarity to compare two samples drawn from two populations differing only in the location parameter. We call such a test as test of homogeneity. In practice the power of such a bidirectional test will be studied referring to the absolute value of the shiftδand to the same probability models considered by Fried and Dehling.
Modelling Turbulent Heat Transfer in a Natural Convection Flow  [PDF]
Claudia Zimmermann, Rodion Groll
Journal of Applied Mathematics and Physics (JAMP) , 2014, DOI: 10.4236/jamp.2014.27073
Abstract:

In this paper a numerical study of a turbulent, natural convection problem is performed with a compressible Large-Eddy simulation. In a natural convection the fluid is accelerated by local density differences and a resulting pressure gradient. Directly at the heated walls the temperature distribution is determinate by increasing temperature gradients. In the centre region convective mass exchange is dominant. Density changes due to temperature differences are considered in the numerical model by a compressible coupled model. The obtained numerical results of this study are compared to an analogue experimental setup. The fluid properties profiles, e.g. temperature and velocity, show an asymmetry which is caused by the non-Boussinesq effects of the fluid. The investigated Rayleigh number of this study lies at Ra = 1.58 × 109.

 

Experimental and Numerical Investigation of a Rayleigh-Bénard Convection Affected by Coriolis Force  [PDF]
Claudia Zimmermann, Rodion Groll
Journal of Flow Control, Measurement & Visualization (JFCMV) , 2014, DOI: 10.4236/jfcmv.2014.24018
Abstract: In this paper the influence of an impressed Coriolis force field on the configuration of a turbulent Rayleigh-Bénard convection problem is investigated in an experimental and numerical study. The main purpose of both studies lie on the analysis of a possible stabilising effect of a Coriolis acceleration on the turbulent unsteady structures inside the fluid. The relative Coriolis acceleration which is caused in the atmosphere by the earth rotation is realised in the experimental study by a uniform-rotational movement of the setup in a large-scale centrifuge under hyper-gravity. The same conditions as in the atmosphere in the beginning of a twister or hurricane should be realised in the experiment. The investigated Rayleigh numbers lie between 2.33 × 106 ≤ Ra ≤ 4.32 × 107.
The Differentiation of Phonological and Morphological Intrusion for the Two-Dimensional Orthography  [PDF]
Yang Lee, Claudia Carello
Psychology (PSYCH) , 2016, DOI: 10.4236/psych.2016.79123
Abstract: The writing systems have been developed by regard that how sound is written to express phonology in letters. So to interpret the written words, the phonological orthography is deemed to have serious contribution. In researches, the decoding processes of phonology have been concerned, proposing some theories as orthographic depth hypothesis, and phonological primary principle. However the other aspect of orthography has been raised with regard of how to reserve morphology in writing. Also to understand the written words, the analysis of the morphological orthography is viewed to help readers. So in researches, some of morphological effects have been analyzed. This study presupposed two-dimensional category of phonology and morphology to set various writing systems. Attempting to confirm the two dimensions, an experiment was designed to analyze both of phonological and morphological effect. For the purposes, the intrusion effect of phonology or morphology was proposed as what is sensitive to working of the two dimensions. This study observed the intrusion of phonology which influenced on the semantic task which required judging whether same or different in meaning between prime and target. And also the intrusion of morphology was observed when judging sounds between prime and target was required. This study sampled Korean and Chinese words both of which belong to Korean language, and each of which is posited by this study to be distributed differently in the two dimensions of phonology and morphology. The analysis of the results showed both of the sound and meaning intrusion, concluding that Korean writing system kept the two-dimensional category of phonology and morphology. Therefore this study pointed out the limit of one-dimensional category hitherto accepted, where each of the phonological and morphological orthography is posed at each of the two extremes in one-dimension, requiring the further tests on the other languages to make generalization of the two-dimensional category of phonology and morphology proposed and supported by this study.
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