scholarly journals Approximation of discontinuous functions of three variables by discontinuous interpolation splines

Author(s):  
Iuliia Pershyna

In this paper, discontinuous interpolation splines of three variables are constructed and a method for reconstructing of the discontinuous internal structure of a three-dimensional body by constructed splines is proposed. It is believed that a three-dimensional object, which is described by a function of three variables with discontinuities of the first kind on a given grid of nodes, is completely covered by a system of parallelepipeds. The experimental data are the one-sided value of the discontinuous function in a given grid of nodes. In the article, theorems on interpolation properties and the error of the constructed discontinuous structures are formulated and proved. Moreover, the constructed discontinuous interpolation splines include, as a special case, classical continuous splines. The developed approximation method can be applied in three-dimensional mathematical modeling of discontinuous processes, including in computed tomography.

Author(s):  
H.W. Deckman ◽  
B.F. Flannery ◽  
J.H. Dunsmuir ◽  
K.D' Amico

We have developed a new X-ray microscope which produces complete three dimensional images of samples. The microscope operates by performing X-ray tomography with unprecedented resolution. Tomography is a non-invasive imaging technique that creates maps of the internal structure of samples from measurement of the attenuation of penetrating radiation. As conventionally practiced in medical Computed Tomography (CT), radiologists produce maps of bone and tissue structure in several planar sections that reveal features with 1mm resolution and 1% contrast. Microtomography extends the capability of CT in several ways. First, the resolution which approaches one micron, is one thousand times higher than that of the medical CT. Second, our approach acquires and analyses the data in a panoramic imaging format that directly produces three-dimensional maps in a series of contiguous stacked planes. Typical maps available today consist of three hundred planar sections each containing 512x512 pixels. Finally, and perhaps of most import scientifically, microtomography using a synchrotron X-ray source, allows us to generate maps of individual element.


2013 ◽  
Vol 10 (01) ◽  
pp. 149-172 ◽  
Author(s):  
GENG CHEN ◽  
ROBIN YOUNG ◽  
QINGTIAN ZHANG

We prove shock formation results for the compressible Euler equations and related systems of conservation laws in one space dimension, or three dimensions with spherical symmetry. We establish an L∞ bound for C1 solutions of the one-dimensional (1D) Euler equations, and use this to improve recent shock formation results of the authors. We prove analogous shock formation results for 1D magnetohydrodynamics (MHD) with orthogonal magnetic field, and for compressible flow in a variable area duct, which has as a special case spherically symmetric three-dimensional (3D) flow on the exterior of a ball.


2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Simon Zabler ◽  
Michael Maisl ◽  
Peter Hornberger ◽  
Jochen Hiller ◽  
Christian Fella ◽  
...  

AbstractAfter an incremental development which took place over four decades, X-ray imaging has become an important tool for non-destructive testing and evaluation. Computed Tomography (CT) in particular beholds the power of determining the location of flaws and inclusions (e. g. in castings and composites) in three-dimensional object coordinates. Therefore, and thanks to a speed-up of the measurement, CT is now routinely considered for in-line inspection of electronics, castings and composites. When precision and not speed is important, Micro-CT (μCT) can be employed for Dimensional Measurements (DM, e. g. quality assurance and shape verification), as well as for in situ testing, and for characterizing micro-structures in metals and composites. Using appropriate image processing and analysis μCT can determine the local fibre orientation in composites, the granular morphology of battery cathodes or the inter-connectivity of certain phases in casting alloys.Today, the large variety of X-ray instruments and methods poses an application problem which requires experience and a lot of knowledge for deciding which technique applies best to the task at hand. Application-specific guidelines exist for X-ray radiography testing (RT) only, whereas standardization has been applied to CT, unfortunately leaving out high resolution subμ CT, and nano-CT. For the latter exist an equally high number of NDT applications, however these instruments still necessitate a profound expertise. The task is to identify key industrial applications and push CT from system standardization to application specific automation.


2019 ◽  
Vol 9 (3) ◽  
pp. 516 ◽  
Author(s):  
Sneha Samal ◽  
Marcela Kolinova ◽  
Hubert Rahier ◽  
Giovanni Dal Poggetto ◽  
Ignazio Blanco

The internal structure of fiber reinforced geopolymer composite was investigated by microfocus X-ray computed tomography (µCT) under mechanical impact. µCT is a non-destructive, multi approach technique for assessing the internal structures of the impacted composites without compromising their integrity. The three dimensional (3D) representation was used to assess the impact damage of geopolymer composites reinforced with carbon, E-glass, and basalt fibers. The 3D representations of the damaged area with the visualization of the fiber rupture slices are presented in this article. The fiber pulls out, and rupture and matrix damage, which could clearly be observed, was studied on the impacted composites by examining slices of the damaged area from the center of the damage towards the edge of the composite. Quantitative analysis of the damaged area revealed that carbon fabric reinforced composites were much less affected by the impact than the E-glass and basalt reinforced composites. The penetration was clearly observed for the basalt based composites, confirming µCT as a useful technique for examining the different failure mechanisms for geopolymer composites. The durability of the carbon fiber reinforced composite showed better residual strength in comparison with the E-glass fiber one.


2021 ◽  
Vol 13 (1-2) ◽  
pp. 357-376
Author(s):  
Marat Gorodezky ◽  

The article considers creationism as a historically relevant principle in the scientific and philosophic aspects denoting the ontological structure of the world. Outside of the religious interpretation, the author speaks of the dialectics of creation, which is revealed as an implicative connection of the one and nothing. Logical inversion (logical turn), acting from within this implicative connection, is postulated as the principle of a fundamental negation, which, according to the author, forms the true and dramatic essence of the world as a creation. The author distances himself from the widespread discussion between evolutionism and scientific creationism, stating that it does not correspond to the very subject of creationism, understood as the implication of a real from nothing. The author focuses on considering ‘nothing’ as a purely dialectical / metaphysical principle and relies partly on the Hegel’s dialectic of ‘being’ and ‘nothing’, and partly on the neoplatonic concept of the one. Rejecting the medieval interpretation of the temporal beginning and the Hegel’s identity, he deduces a scheme of the logical connection between the one and the difference, which postulates the inversion (turnover) forming the creation - the one and the difference disjunctively change places, the one becomes the real, and the difference out of the one becomes nothing. It is argued that this postulate, in particular, refutes the thesis about the ‘fall into sin’. In the second part of the article, a spatial-phenomenological hypothesis is presented: the author provides a description of the space as a geometrical-semantic plane (projective structure). This hypothesis follows from the phenomenological problem of the duality of a geometric object, which results in the problem of ontological transition between a point and a line (in the aporia of the Eleats) and the related problem of spatial congruence / parallelism. According to the author, the potential for solving these not essentially mathematical, but metaphysical questions is the projective geometry, in which parallel lines intersect at ‘point at infinity’, and space is complemented by the ‘plane at infinity’. The essence of the solution consists, firstly, in the assumption of the single plane, which underlies the transition, and secondly, in the description of the perceived world as a result of a specific turn over and closure of this plane, forming the projective structure. The key in this part is the demonstration of the surface of a three-dimensional object as a phenomenon of perceptual-semantic unfolding, which can be imagined as an action of consciousness, consistently reducing the usual scheme. An important aspect of considering the projective structure is the correlation with ‘the Plane’ by G. Deleuze. The general idea of the article is that the dialectical scheme of creation and the projective structure of the space coincide: the logical inversion (logical turn), acting in connection of the one and nothing, and projective structural turnover – are the same things.


Author(s):  
Roman Kremen

The article presents a metaphysical concept, in the main tesa of which the simplest discrete element of physical reality is constituted — designated as a protomonad — which forms the basis of spatial forms of materiality, including space itself as such. The genesis of the protomonad is clarified by a certain way interpreted rotation of the spiritual essence, which in itself does not have an extension, and both the indicated essence and its rotation have a metaphysical order, and the dimension of physical space finds a rational interpretation through the characteristics of metaphysical rotation. The semantic aspects of complex mathematical constructs are considered that convey the semantics of rotations, and quite reasonably proposed by some mathematicians as the unified foundations of mathematics and physics, where the properties of constructs act as a mathematically strict co-proof of the validity of the concept. The meaning of number is explained as a method of restriction on infinite pre-physical multiplicity, and finite natural multiplicities are the result of such restrictions; the most important special case is the three-dimensional spatial metric given in the experiment, which appears as a restriction of an infinite-dimensional metaphysical space. The so-called principle of genetic inheritance is formulated, which makes it possible to remove the dialectical opposition between the one and the multiple and illustrates the categories of time and space as dialectical oppositions.


2011 ◽  
Vol 19 (1) ◽  
pp. 1 ◽  
Author(s):  
Robert T Dehoff

This summary paper provides an overview of the content of stereology. The typical problem at hand centers around some three dimensional object that has an internal structure that determines its function, performance, or response. To understand and quantify the geometry of that structure it is necessary to probe it with geometric entities: points, lines, planes volumes, etc. Meaningful results are obtained only if the set of probes chosen for use in the assessment is drawn uniformly from the population of such probes for the structure as a whole. This requires an understanding of the population of each kind of probe. Interaction of the probes with the structure produce geometric events which are the focus of stereological measurements. In almost all applications the measurement that is made is a simple count of the number of these events. Rigorous application of these requirements for sample design produce unbiased estimates of geometric properties of features in the structure no matter how complex are the features or what their arrangement in space. It is this assumption-free characteristic of the methodology that makes it a powerful tool for characterizing the internal structure of three dimensional objects.


2018 ◽  
Vol 30 (01) ◽  
pp. 1850004 ◽  
Author(s):  
Che-Wei Liao ◽  
Chia-Jui Hsieh ◽  
Heng-Li Huang ◽  
Lih-Jyh Fuh ◽  
Chih-Wei Kuo ◽  
...  

Digital periapical radiography is widely used in clinical dentistry because the technique is relatively simple and inexpensive. However, the main drawback of periapical radiography is that it represents a three-dimensional object in a two-dimensional film due to its inherent projection technique. The objective of this study was to develop a prototype intraoral computed tomosynthesis system, which can provide quasi-three-dimensional (so-called 2.5D) images. We developed a prototype intraoral computed tomosynthesis machine. Regular digital periapical radiography, computed tomosynthesis scanning, and computed tomography scanning of a human central incisor were performed. Then, reconstruction images obtained using computed tomosynthesis and computed tomography approaches were quantitatively evaluated using the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). From the experimental results, compared with periapical radiographic images, reconstruction images obtained using the computed tomosynthesis approach revealed detailed microstructures in different depth sections. In addition, the SNR and CNR of reconstruction images obtained using the computed tomography approach was better than those of the images obtained using the computed tomosynthesis approach. However, the differences could not be clearly identified by the naked eye. The preliminary experimental results indicate that an intraoral computed tomosynthesis system may be useful for clinical dental diagnosis.


2019 ◽  
Vol 2 (3) ◽  
pp. 116-121
Author(s):  
Akbar Begmatov

We consider the problem of determining the internal structure of the three-dimensional object from integral data obtained by tomografic scanning using a cone scheme over a family of right circular cones. Stability estimates are proven and inversion formula is obtained.


2017 ◽  
Vol 73 (1) ◽  
pp. 48-52 ◽  
Author(s):  
Tomasz Próchniak ◽  
Iwona Rozempolska-Rucińska ◽  
Monika Petrykowska ◽  
Grzegorz Zięba ◽  
Brygida Ślaska ◽  
...  

The aim of the study was to assess the cognitive abilities of horses in recognizing humans by sight and smell. Two experiments were performed. In the first experiment, the behaviour of horses exposed to a visual stimulus (photographs of familiar and unfamiliar people) was observed. The second experiment examined their behaviour evoked by an olfactory stimulus. The following variables was assessed: the duration of approach to the object in seconds (s), interest in the object, a negative reaction, the duration of the observation of the object (s), the duration of looking with the left eye and the right eye (s), and other signs of interest, e.g. licking, grasping with lips, and touching the object. It was found that the horses were able to identify the human by transferring the identification of a three-dimensional object (a person that positively conditioned the horse) to a two-dimensional object (a photograph of that person’s face). It was also shown that the horses used the sense of smell in associating clothes with the person wearing them (the one who positively conditioned the horse). It was found that positively conditioned horses reacted more strongly to the smell of human clothes than to a photograph of the human.


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