scholarly journals Generation of 3D Tumor Models from DICOM Images for Virtual Planning of its Recession

2020 ◽  
Vol 29 (54) ◽  
pp. e10173
Author(s):  
Oscar Rodríguez-Bastidas ◽  
Hermes Fabián Vargas-Rosero
Keyword(s):  
Medical Images ◽  
Computational Cost ◽  
Three Dimensional ◽  
Tumor Model ◽  
Reconstruction Technique ◽  
Virtual Planning ◽  
New Techniques ◽  
Segmentation Strategy ◽  
Long Time ◽  
Three Dimensional Models

Medical images are essential for diagnosis, planning of surgery and evolution of pathology. The advances in technology have developed new techniques to obtain digital images with more details, in return this has also led to disadvantages, such as: the analysis of large volumes of information, long time to determine an affected region and difficulty in defining the malignant tissue for its later extirpation, among the most relevant. This article presents an image segmentation strategy and the optimization of a method for generating three-dimensional models. A prototype was implemented in which it was possible to evaluate the segmentation algorithms and 3D reconstruction technique, allowing to visualize the tumor model from different points of view through virtual reality. In this investigation, we evaluate the computational cost and user experience, the parameters selected in terms of computational cost are the time and consumption of RAM, we used 140 MRI images each with dimensions 260x320 pixel, and as a result, we obtained an approximate time of 37.16s and consumption in RAM of 1.3GB. Another experiment carried out is the segmentation and reconstruction of a tumor, this model is formed by a three-dimensional mesh made up of 151 vertices and 318 faces. Finally, we evaluate the application, with a usability test applied to a sample of 20 people with different areas of knowledge. The results show that the graphics presented by the software are pleasant, they also show that the application is intuitive and easy to use. Additionally, it is mentioned that it helps improve the understanding of medical images.

Skeletonization Accelerated Solution of Crank-Nicolson Method for Solving Three-Dimensional Parabolic Equation

2020 ◽  
Vol 35 (9) ◽  
pp. 1006-1011
Author(s):  
Hafiz Rasool ◽  
Chen Jun ◽  
Xiao-Min Pan ◽  
Xin-Qing Sheng
Keyword(s):  
Parabolic Equation ◽  
Computational Cost ◽  
Three Dimensional ◽  
Accurate Solution ◽  
Special Treatment ◽  
Conditional Stability ◽  
Implicit Schemes ◽  
Long Time ◽  
Computationally Intensive ◽  
Crank Nicolson

Parabolic equation models discretized with the finite difference method have been extensively studied for a long time. However, several explicit and implicit schemes exist in the literature. The advantage in explicit schemes is its simplicity, while its disadvantage is conditional stability. On the other hand, implicit schemes are unconditionally stable but require special treatment for a fast and accurate solution such as the Crank-Nicolson (CN) method. This method becomes computationally intensive for problems with dense meshes. The resulting matrix from the CN in two and three-dimensional cases requires high computational resources. This paper applies hierarchical interpolative factorization (HIF) to reduce the computational cost of the CN method. Numerical experiments are conducted to validate the proposed HIF acceleration.

scholarly journals Comparison of Cohesive Models in EDEM and LIGGGHTS for Simulating Powder Compaction

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2341 ◽  
Author(s):  
Cristina Ramírez-Aragón ◽  
Joaquín Ordieres-Meré ◽  
Fernando Alba-Elías ◽  
Ana González-Marcos
Keyword(s):  
Computational Cost ◽  
Three Dimensional ◽  
Maximum Force ◽  
Compaction Process ◽  
Computational Costs ◽  
Cohesive Models ◽  
Contact Models ◽  
Three Dimensional Models ◽  
Simulation Parameters ◽  
Cohesive Material

The purpose of this work was to analyse the compaction of a cohesive material using different Discrete Element Method (DEM) simulators to determine the equivalent contact models and to identify how some simulation parameters affect the compaction results (maximum force and compact appearance) and computational costs. For this purpose, three cohesion contact models were tested: linear cohesion in EDEM, and simplified Johnson-Kendall-Roberts (SJKR) and modified SJKR (SJKR2) in LIGGGHTS. The influence of the particle size distribution (PSD) on the results was also investigated. Further assessments were performed on the effect of (1) selecting different timesteps, (2) using distinct conversion tolerances to export the three-dimensional models to standard triangle language (STL) files, and (3) moving the punch with different speeds. Consequently, we determined that a timestep equal to a 10% Rayleigh timestep, a conversion tolerance of 0.01 mm, and a punch speed of 0.1 m/s is adequate for simulating the compaction process using the materials and the contact models in this work. The results showed that the maximum force was influenced by the PSD due to the rearrangement of the particles. The PSD was also related to the computational cost because of the number of simulated particles and their sizes. Finally, an equivalence was found between the linear cohesion and SJKR2 contact models.

scholarly journals STUDY OF DNIEPER’S ISLANDS’ SHORELINE CHANGE DYNAMICS WITHIN KIEV REGION (AT THE EXAMPLE OF VELYKIY PIVNICHNIY ISLAND)

2017 ◽  
pp. 84-88
Author(s):  
O. Tomchenko ◽  
L. Mazurkiewicz ◽  
A. Malets
Keyword(s):  
Three Dimensional ◽  
Remote Sensing Data ◽  
Shoreline Change ◽  
Coastal Landscape ◽  
Conservation Area ◽  
City Formation ◽  
Long Time ◽  
Grand Island ◽  
Three Dimensional Models ◽  
The 19Th Century

Changes of Dnieper’s islands’ landscapes within Kyiv at the example of Velykiy Pivnichniy Island are studied. Using GIS, cartographic materials and remote sensing data the island’s square dynamic for more than seventy years is obtained. During decoding vector layers – the contours of the coastline of the island and the island area – were created and island’s square for 1942, 1975, 1985, 1990, 2000, 2015 years was estimated. Using module implemented in ArcScene ArcGIS the dynamics of long-term changes of Velykiy Island’s shape was modeled and clearly reflected in the form of three-dimensional models. The coastal landscape of Kyiv began to rapidly change for the past 100-200 years due to rapid urban sprawl. Before it Dnieper’s backwater in Kyiv formed by glaciers and it became the basis for floodplain in Kyiv region for a long time. In the 19th century held-rectifying work was conducted and it greatly influenced the coastal landscape of our city. Formation of new islands, such as Grand Island and changes of old islands (such as the island of Murom united with Truhanov Island) has begun. Great Island consisted of 2 parts, one of which joined the island much later than the first part of the island was formed. From 1950 to 1990 the island had the largest area and it was unchanged while this period. The rapid square reduction began in the 1990s when sand mining started for the purpose of Troieshchyna district building. Currently the island is used as a career for the extraction of sand, which is important for development of different districts, including cottages on the site of meadows and oak forests on north of the Gulf of Camel. It is a negative factor for the island, where there are different species of animals and plants are located. The island is also an example of modern Dnieper floodplain formation and it should be preserved as a conservation area of the city.

scholarly journals Simulation Models for Solar Photovoltaic Materials

2021 ◽  
pp. 114-133
Author(s):  
M. Rizwan
Keyword(s):  
Solar Cell ◽  
Band Structure ◽  
Computer Modelling ◽  
Three Dimensional ◽  
Simulation Models ◽  
Semiconductor Materials ◽  
Long Time ◽  
Three Dimensional Models ◽  
Materials Used ◽  
Device Operation

Semiconducting materials have dominated the photovoltaic industry for a long time. The advancement in solar cell technology is significantly influenced by computer modelling, designing and simulations of the semiconductor materials used for the device operation. Different modelling techniques including one, two and three dimensional models had been employed to comprehend the device operation of solar cell and other electronic devices based on semiconductor materials such as silicon and gallium arsenide. The performance of computing power is increasing with the passage of time in order to improve modelling and designing of different semiconductor materials for solar cell devices. In this chapter, different reported semiconductor materials, their standard characteristics and basic history of modelling, standard models used in photovoltaic industry and principles of modelling such as carrier statistics, transitions, band structure and mobility are explained in detail. Different characteristics of semiconductor material like the carrier transportation, carrier statistics, band structure, and heavy doping effect and carrier generations are described with respect to material modelling.

Two- and Three-Dimensional Models of Dispersion Based upon Measurements in the North Sea

1991 ◽  
Vol 24 (10) ◽  
pp. 45-53 ◽  
Author(s):  
G. C. van Dam
Keyword(s):  
North Sea ◽  
Three Dimensional ◽  
Historical Review ◽  
Particle Simulation ◽  
Simulation Methods ◽  
The North ◽  
Recent Developments ◽  
Long Time ◽  
The North Sea ◽  
Three Dimensional Models

After a brief historical review some recent developments are discussed, with an emphasis on particle simulation methods. Examples are shown of relatively short and relatively long time scale applications in connection with accidental spills and problems of continuous sources respectively.

scholarly journals Key Aspects in 3D Fatigue Crack Closure Numerical Modelling

2018 ◽  
Vol 774 ◽  
pp. 441-446 ◽  
Author(s):  
Antonio González-Herrera ◽  
Daniel Camas ◽  
J. Garcia-Manrique
Keyword(s):  
Fatigue Crack ◽  
Numerical Modelling ◽  
Crack Closure ◽  
Three Dimensional ◽  
3D Models ◽  
Fatigue Crack Closure ◽  
Long Time ◽  
Dimensional Models ◽  
Three Dimensional Models ◽  
Key Aspects

Since long time, fatigue crack closure has been studied by means of finite element models. Initially by bi-dimensional models and recently, due to the higher computational capabilities, the use of three-dimensional models has been extended, providing a wider comprehension of the problem. Starting with the methodology used for 2D cases, a specific methodology for 3D models has been developed. Key parameters affecting the model have been analyzed and recommendations have been established. The numerical accuracy is evaluated in terms of crack closure and opening values. They main issues studied are the material behaviour, the loading cycles and crack growth scheme, the contact simulation, the meshing and the element size at the crack tip and along the thickness, the plastic wake computed and the opening and closure definition considered. This paper summarises the main learning and recommendations from the latest numerical modelling experience of the authors.

Plastic replicas as three-dimensional models of pulps

1975 ◽  
Vol 39 (8) ◽  
pp. 544-546
Author(s):  
HL Wakkerman ◽  
GS The ◽  
AJ Spanauf
Keyword(s):  
Three Dimensional ◽  
Dimensional Models ◽  
Three Dimensional Models

Guided surgery with 3D printed device: a case report

2020 ◽  
Author(s):  
Michelle Carvalho de Sales ◽  
Rafael Maluza Flores ◽  
Julianny da Silva Guimaraes ◽  
Gustavo Vargas da Silva Salomao ◽  
Tamara Kerber Tedesco ◽  
...  
Keyword(s):  
Operating Time ◽  
Three Dimensional ◽  
Conventional Technique ◽  
Cervical Region ◽  
Mean Deviation ◽  
Apical Region ◽  
Virtual Planning ◽  
Surgical Guide ◽  
Surgical Guides ◽  
High Level

Dental surgeons need in-depth knowledge of the bone tissue status and gingival morphology of atrophic maxillae. The aim of this study is to describe preoperative virtual planning of placement of five implants and to compare the plan with the actual surgical results. Three-dimensional planning of rehabilitation using software programs enables surgical guides to be specially designed for the implant site and manufactured using 3D printing. A patient with five teeth missing was selected for this study. The patient’s maxillary region was scanned with CBCT and a cast model was produced. After virtual planning using ImplantViewer, five implants were placed using a printed surgical guide. Two weeks after the surgical procedure, the patient underwent another CBCT scan of the maxilla. Statistically significant differences were detected between the virtually planned positions and the actual positions of the implants, with a mean deviation of 0.36 mm in the cervical region and 0.7 mm in the apical region. The surgical technique used enables more accurate procedures when compared to the conventional technique. Implants can be better positioned, with a high level of predictability, reducing both operating time and patient discomfort.

Validation of a Belt Model for Prediction of Hub Forces from a Rolling Tire4

2009 ◽  
Vol 37 (2) ◽  
pp. 62-102 ◽  
Author(s):  
C. Lecomte ◽  
W. R. Graham ◽  
D. J. O’Boy
Keyword(s):  
Internal Pressure ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Prediction Method ◽  
Analytical Models ◽  
Beam Model ◽  
Impedance Boundary ◽  
Bending Waves ◽  
Tire Rotation ◽  
Three Dimensional Models

Abstract An integrated model is under development which will be able to predict the interior noise due to the vibrations of a rolling tire structurally transmitted to the hub of a vehicle. Here, the tire belt model used as part of this prediction method is first briefly presented and discussed, and it is then compared to other models available in the literature. This component will be linked to the tread blocks through normal and tangential forces and to the sidewalls through impedance boundary conditions. The tire belt is modeled as an orthotropic cylindrical ring of negligible thickness with rotational effects, internal pressure, and prestresses included. The associated equations of motion are derived by a variational approach and are investigated for both unforced and forced motions. The model supports extensional and bending waves, which are believed to be the important features to correctly predict the hub forces in the midfrequency (50–500 Hz) range of interest. The predicted waves and forced responses of a benchmark structure are compared to the predictions of several alternative analytical models: two three dimensional models that can support multiple isotropic layers, one of these models include curvature and the other one is flat; a one-dimensional beam model which does not consider axial variations; and several shell models. Finally, the effects of internal pressure, prestress, curvature, and tire rotation on free waves are discussed.

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