Singularity consideration in the integral equations for contactless inductive flow tomography

2018 ◽  
Vol 37 (4) ◽  
pp. 1366-1375
Author(s):  
Ralf T. Jacobs ◽  
Thomas Wondrak ◽  
Frank Stefani
Keyword(s):  
Singular Point ◽  
Integral Equations ◽  
Focal Point ◽  
Three Dimensional ◽  
Magnetic Flux Density ◽  
Forward Solution ◽  
Content Type ◽  
Electrically Conducting ◽  
Close Proximity ◽  
High Degree

Purpose The contactless inductive flow tomography is a procedure that enables the reconstruction of the global three-dimensional flow structure of an electrically conducting fluid by measuring the flow-induced magnetic flux density outside the melt and by subsequently solving the associated linear inverse problem. The purpose of this study is to improve the accuracy of the computation of the forward problem, since the forward solution primarily determines the accuracy of the inversion. Design/methodology/approach The tomography procedure is described by a system of coupled integral equations where the integrals contain a singularity when a source point coincides with a field point. The integrals need to be evaluated to a high degree of precision to establish an accurate foundation for the inversion. The contribution of a singular point to the value of the surface and volume integrals in the system is determined by analysing the behaviour of the fields and integrals in the close proximity of the singularity. Findings A significant improvement of the accuracy is achieved by applying higher order elements and by attributing special attention to the singularities inherent in the integral equations. Originality/value The contribution of a singular point to the value of the surface integrals in the system is dependent upon the geometry of the boundary at the singular point. The computation of the integrals is described in detail and the improper surface and volume integrals are shown to exist. The treatment of the singularities represents a novelty in the contactless inductive flow tomography and is the focal point of this investigation.

Evaluation of U-Net Based Architectures for Automatic Aortic Dissection Segmentation

2022 ◽  
Vol 3 (1) ◽  
pp. 1-16
Author(s):  
Bradley Feiger ◽  
Erick Lorenzana-Saldivar ◽  
Colin Cooke ◽  
Roarke Horstmeyer ◽  
Muath Bishawi ◽  
...  
Keyword(s):  
Average Distance ◽  
Three Dimensional ◽  
False Lumen ◽  
Dice Similarity Coefficient ◽  
True Lumen ◽  
Content Type ◽  
Segmentation Accuracy ◽  
Upward Direction ◽  
Aortic Dissections ◽  
High Degree

Segmentation and reconstruction of arteries is important for a variety of medical and engineering fields, such as surgical planning and physiological modeling. However, manual methods can be laborious and subject to a high degree of human variability. In this work, we developed various convolutional neural network ( CNN ) architectures to segment Stanford type B aortic dissections ( TBADs ), characterized by a tear in the descending aortic wall creating a normal channel of blood flow called a true lumen and a pathologic channel within the wall called a false lumen. We introduced several variations to the two-dimensional ( 2D ) and three-dimensional (3 D ) U-Net, where small stacks of slices were inputted into the networks instead of individual slices or whole geometries. We compared these variations with a variety of CNN segmentation architectures and found that stacking the input data slices in the upward direction with 2D U-Net improved segmentation accuracy, as measured by the Dice similarity coefficient ( DC ) and point-by-point average distance ( AVD ), by more than 15\% . Our optimal architecture produced DC scores of 0.94, 0.88, and 0.90 and AVD values of 0.074, 0.22, and 0.11 in the whole aorta, true lumen, and false lumen, respectively. Altogether, the predicted reconstructions closely matched manual reconstructions.

scholarly journals Functional Identification of Rubber Oxygenase (RoxA) in Soil and Marine Myxobacteria

2013 ◽  
Vol 79 (20) ◽  
pp. 6391-6399 ◽  
Author(s):  
Jakob Birke ◽  
Wolf Röther ◽  
Georg Schmitt ◽  
Dieter Jendrossek
Keyword(s):  
Chemical Reduction ◽  
Three Dimensional ◽  
Visible Spectrum ◽  
Functional Identification ◽  
Gram Positive ◽  
Zone Formation ◽  
Content Type ◽  
Gram Positive Bacteria ◽  
Degrading Bacteria ◽  
High Degree

ABSTRACTThe rubber oxygenase (RoxA) ofXanthomonassp. strain 35Y (RoxAXsp) is so far the only known extracellularc-type diheme cytochrome that is able to cleave poly(cis-1,4-isoprene). All other rubber-degrading bacteria described are Gram positive and employ a nonheme protein (latex-clearing protein [Lcp]) for the postulated primary attack of polyisoprene. Here, we identified RoxA orthologs in the genomes ofHaliangium ochraceum,Myxococcus fulvus,Corallococcus coralloides, andChondromyces apiculatus. TheroxAorthologs ofH. ochraceum(RoxAHoc),C. coralloidesBO35 (RoxACco), andM. fulvus(RoxAMfu) were functionally expressed in a ΔroxA Xanthomonassp. 35Y background. All RoxA orthologs oxidatively cleaved polyisoprene, as revealed by restoration of clearing-zone formation and detection of 12-oxo-4,8-dimethyltrideca-4,8-diene-1-al (ODTD) as a cleavage product. RoxAXsp, RoxAMfu, and RoxACcowere purified and biochemically characterized. The optimal temperature of RoxACcoand RoxAMfuwas between 22 and 30°C. All RoxA orthologs as isolated showed an oxidized UV-visible spectrum. Chemical reduction of RoxACcoand RoxAMfuindicated the presence of two slightly different heme centers with absorption maxima between 549 and 553 nm, similar to RoxAXsp. Sequence analysis and modeling of the three-dimensional structures of the RoxA orthologs revealed a high degree of similarity to the recently solved RoxAXspstructure and included several conserved residues, notably, W302, F317, and a MauG motif at about H517. Lcp-like sequences were not detected in the genomes of theXanthomonassp. 35Y,H. ochraceum,M. fulvus, andC. coralloides. No RoxA orthologs were found in Gram-positive bacteria, and this first description of functional RoxA in Gram-negative bacteria other thanXanthomonasproves that RoxA is more common among rubber degraders than was previously assumed.

Bringing person-centeredness and active involvement into reality

2015 ◽  
Vol 115 (6) ◽  
pp. 518-533 ◽  
Author(s):  
Rikke Torenholt ◽  
Gitte Engelund ◽  
Ingrid Willaing
Keyword(s):  
Chronic Illness ◽  
Patient Education ◽  
Group Dynamics ◽  
Focal Point ◽  
Self Management ◽  
Patient Centeredness ◽  
Content Type ◽  
Active Involvement ◽  
High Degree ◽  
Very High

Purpose – The purpose of this paper is to examine the use and applicability of cultural probes – an explorative participatory method to gain insights into a person’s life and thoughts – to achieve person-centeredness and active involvement in self-management education for people with chronic illness. Design/methodology/approach – An education toolkit inspired by the ideas of cultural probes was developed and feasibility tested in 49 education settings in Denmark. Questionnaires, interviews, and observations were used to collect data, which were analysed using descriptive statistics, analysis of variance, and systematic text condensation. Findings – Educators emphasized the applicability of the toolkit, and between 69 and 82 per cent of educators reported that the toolkit supported them in facilitating person-centred education and active involvement to a high or very high degree. Most educators (81 per cent) reported that they would like to apply the toolkit again in future education to a high or very high degree. Five categories of educator experiences were identified: interaction and activity; person-centeredness; group dynamics and synergy; openness; and light and cheerful atmosphere. Educators talked significantly less in situations where the toolkit was applied. This indicates the ability of the toolkit to facilitate talk among participants and thereby let participants become the focal point of education. Applying cultural probes in patient education targeting people with chronic illness seems to be a useful method to achieve patient-centeredness and active involvement in patient education and to support educators in facilitating this process. Originality/value – Introducing fully flexible education toolkits inspired by cultural probes may, in the future, lead to improved self-management patient education among people with chronic illness.

Numerical exploration of heat and mass transport for the flow of nanofluid subject to Hall and ion slip effects

2020 ◽  
Vol 16 (5) ◽  
pp. 951-965
Author(s):  
Rahila Naz ◽  
Muhammad Sohail ◽  
T. Hayat
Keyword(s):  
Numerical Solutions ◽  
Three Dimensional ◽  
Content Type ◽  
Electrically Conducting ◽  
Analytical And Numerical Solutions ◽  
Heating Effects ◽  
Slip Effects ◽  
Layer Analysis ◽  
Homotopy Analysis ◽  
Ion Slip

PurposeThis paper addresses the three-dimensional flow of viscous nanofluid bounded by two plates. The lower plate stretches while the upper plate remains stationary. The fluid is electrically conducting in the presence of an applied magnetic field. In addition, the Hall, ion slip and Joule heating effects are retained. Governing equations for the considered physical happening are modeled under the phenomenon of boundary layer analysis.Design/methodology/approachBoth analytical and numerical solutions for the resulting nonlinear system are derived. Numerical solutions have been presented by using bvp4c and NDSolve techniques. The homotopy analysis method is utilized for the development of convergent analytical solutions. A comparative study for the presented solutions is made. An excellent agreement between analytical and numerical solutions is noticed.FindingsThe dimensionless velocities, temperature and concentration are examined physically by two-dimensional plots, stream plot and tabular values. It is observed that Hall and ion slip parameters reduce the velocity field and temperature profile increases for the mounting values of the Eckert number.Originality/valueThis manuscript contains the novel contents which comprise the Hall and ion slip effects for the transportation of heat and mass for the flow of viscous nanofluid.

A tubular linear machine with dual Halbach array

2014 ◽  
Vol 31 (2) ◽  
pp. 177-200 ◽  
Author(s):  
Liang Yan ◽  
Lei Zhang ◽  
Zongxia Jiao ◽  
Hongjie Hu ◽  
Chin-Yin Chen ◽  
...  
Keyword(s):  
Flux Density ◽  
Three Dimensional ◽  
Radial Component ◽  
Magnetic Flux Density ◽  
Axial Component ◽  
Structure Parameters ◽  
Force Output ◽  
Content Type ◽  
Halbach Array ◽  
Linear Machine

Purpose – Force output is extremely important for electromagnetic linear machines. The purpose of this study is to explore new permanent magnet (PM) array and winding patterns to increase the magnetic flux density and thus to improve the force output of electromagnetic tubular linear machines. Design/methodology/approach – Based on investigations on various PM patterns, a novel dual Halbach PM array is proposed in this paper to increase the radial component of flux density in three-dimensional machine space, which in turn can increase the force output of tubular linear machine significantly. The force outputs and force ripples for different winding patterns are formulated and analyzed, to select optimized structure parameters. Findings – The proposed dual Halbach array can increase the radial component of flux density and force output of tubular linear machines effectively. It also helps to decrease the axial component of flux density and thus to reduce the deformation and vibration of machines. By using analytical force models, the influence of winding patterns and structure parameters on the machine force output and force ripples can be analyzed. As a result, one set of optimized structure parameters are selected for the design of electromagnetic tubular linear machines. Originality/value – The proposed dual Halbach array and winding patterns are effective ways to improve the linear machine performance. It can also be implemented into rotary machines. The analyzing and design methods could be extended into the development of other electromagnetic machines.

Stereotactic radiosurgery versus stereotactic radiotherapy for patients with vestibular schwannoma: a Leksell Gamma Knife Society 2000 debate

2000 ◽  
Vol 93 (supplement_3) ◽  
pp. 90-92 ◽  
Author(s):  
Mark E. Linskey
Keyword(s):  
Gamma Knife ◽  
Stereotactic Radiotherapy ◽  
Three Dimensional ◽  
Late Recurrence ◽  
Vestibular Schwannomas ◽  
Tumor Control ◽  
Complication Rates ◽  
Content Type ◽  
Single Fraction ◽  
Fine Print

✓ By definition, the term “radiosurgery” refers to the delivery of a therapeutic radiation dose in a single fraction, not simply the use of stereotaxy. Multiple-fraction delivery is better termed “stereotactic radiotherapy.” There are compelling radiobiological principles supporting the biological superiority of single-fraction radiation for achieving an optimal therapeutic response for the slowly proliferating, late-responding, tissue of a schwannoma. It is axiomatic that complication avoidance requires precise three-dimensional conformality between treatment and tumor volumes. This degree of conformality can only be achieved through complex multiisocenter planning. Alternative radiosurgery devices are generally limited to delivering one to four isocenters in a single treatment session. Although they can reproduce dose plans similar in conformality to early gamma knife dose plans by using a similar number of isocenters, they cannot reproduce the conformality of modern gamma knife plans based on magnetic resonance image—targeted localization and five to 30 isocenters. A disturbing trend is developing in which institutions without nongamma knife radiosurgery (GKS) centers are championing and/or shifting to hypofractionated stereotactic radiotherapy for vestibular schwannomas. This trend appears to be driven by a desire to reduce complication rates to compete with modern GKS results by using complex multiisocenter planning. Aggressive advertising and marketing from some of these centers even paradoxically suggests biological superiority of hypofractionation approaches over single-dose radiosurgery for vestibular schwannomas. At the same time these centers continue to use the term radiosurgery to describe their hypofractionated radiotherapy approach in an apparent effort to benefit from a GKS “halo effect.” It must be reemphasized that as neurosurgeons our primary duty is to achieve permanent tumor control for our patients and not to eliminate complications at the expense of potential late recurrence. The answer to minimizing complications while maintaining maximum tumor control is improved conformality of radiosurgery dose planning and not resorting to homeopathic radiosurgery doses or hypofractionation radiotherapy schemes.

scholarly journals A 3D hydrodynamic flow-focusing device for cell sorting

2021 ◽  
Vol 25 (3) ◽  
Author(s):  
Xiaofei Yuan ◽  
Andrew Glidle ◽  
Hitoshi Furusho ◽  
Huabing Yin
Keyword(s):  
Cell Sorting ◽  
Control Strategies ◽  
Three Dimensional ◽  
Hydrodynamic Flow ◽  
Proof Of Concept ◽  
Flow Focusing ◽  
Hydrodynamic Focusing ◽  
Cell Handling ◽  
Fluid Flow Control ◽  
High Degree

AbstractOptical-based microfluidic cell sorting has become increasingly attractive for applications in life and environmental sciences due to its ability of sophisticated cell handling in flow. The majority of these microfluidic cell sorting devices employ two-dimensional fluid flow control strategies, which lack the ability to manipulate the position of cells arbitrarily for precise optical detection, therefore resulting in reduced sorting accuracy and purity. Although three-dimensional (3D) hydrodynamic devices have better flow-focusing characteristics, most lack the flexibility to arbitrarily position the sample flow in each direction. Thus, there have been very few studies using 3D hydrodynamic flow focusing for sorting. Herein, we designed a 3D hydrodynamic focusing sorting platform based on independent sheath flow-focusing and pressure-actuated switching. This design offers many advantages in terms of reliable acquisition of weak Raman signals due to the ability to precisely control the speed and position of samples in 3D. With a proof-of-concept demonstration, we show this 3D hydrodynamic focusing-based sorting device has the potential to reach a high degree of accuracy for Raman activated sorting.

scholarly journals An electrically conducting three‐dimensional iron‐catecholate porous framework

2021 ◽  
Author(s):  
Andre Mähringer ◽  
Markus Döblinger ◽  
Matthias Hennemann ◽  
Christoph Gruber ◽  
Dominik Fehn ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Electrically Conducting ◽  
Porous Framework
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