Kochar, G D; Chakranarayan, A; Kohli, S; Kohli, V S; Khanna, V; Jayan, B; Chopra, S S; Verma, M
2016-05-01
The aim of this study was to quantify the changes in pharyngeal airway space (PAS) in patients with a skeletal class II malocclusion managed by bilateral sagittal split ramus osteotomy for mandibular advancement, using three-dimensional (3D) registration. The sample comprised 16 patients (mean age 21.69±2.80 years). Preoperative (T0) and postoperative (T1) computed tomography scans were recorded. Linear, cross-sectional area (CSA), and volumetric parameters of the velopharynx, oropharynx, and hypopharynx were evaluated. Parameters were compared with paired samples t-tests. Highly significant changes in dimension were measured in both sagittal and transverse planes (P<0.001). CSA measurements increased significantly between T0 and T1 (P<0.001). A significant increase in PAS volume was found at T1 compared with T0 (P<0.001). The changes in PAS were quantified using 3D reconstruction. Along the sagittal and transverse planes, the greatest increase was seen in the oropharynx (12.16% and 11.50%, respectively), followed by hypopharynx (11.00% and 9.07%) and velopharynx (8.97% and 6.73%). CSA increased by 41.69%, 34.56%, and 28.81% in the oropharynx, hypopharynx, and velopharynx, respectively. The volumetric increase was greatest in the oropharynx (49.79%) and least in the velopharynx (38.92%). These established quantifications may act as a useful guide for clinicians in the field of dental sleep medicine. PMID:26691933
Poon, Eric K W; Hayat, Umair; Thondapu, Vikas; Ooi, Andrew S H; Ul Haq, Muhammad Asrar; Moore, Stephen; Foin, Nicolas; Tu, Shengxian; Chin, Cheng; Monty, Jason P; Marusic, Ivan; Barlis, Peter
2015-08-01
Percutaneous coronary intervention (PCI) has shown a high success rate in the treatment of coronary artery disease. The decision to perform PCI often relies on the cardiologist's visual interpretation of coronary lesions during angiography. This has inherent limitations, particularly due to the low resolution and two-dimensional nature of angiography. State-of-the-art modalities such as three-dimensional quantitative coronary angiography, optical coherence tomography and invasive fractional flow reserve (FFR) may improve clinicians' understanding of both the anatomical and physiological importance of coronary lesions. While invasive FFR is the gold standard technique for assessment of the haemodynamic significance of coronary lesions, recent studies have explored a surrogate for FFR derived solely from three-dimensional reconstruction of the invasive angiogram, and therefore eliminating need for a pressure wire. Utilizing advanced computational fluid dynamics research, this virtual fractional flow reserve (vFFR) has demonstrated reasonable correlation with invasive measurements and remains an intense area of ongoing study. However, at present, several limitations and computational fluid dynamic assumptions may preclude vFFR from widespread clinical use. This review demonstrates the tight integration of advanced three-dimensional imaging techniques and vFFR in assessing coronary artery disease, reviews the advantages and disadvantages of such techniques and attempts to provide a glimpse of how such advances may benefit future clinical decision-making during PCI. PMID:26247271
Advanced Three-Dimensional Display System
NASA Technical Reports Server (NTRS)
Geng, Jason
2005-01-01
A desktop-scale, computer-controlled display system, initially developed for NASA and now known as the VolumeViewer(TradeMark), generates three-dimensional (3D) images of 3D objects in a display volume. This system differs fundamentally from stereoscopic and holographic display systems: The images generated by this system are truly 3D in that they can be viewed from almost any angle, without the aid of special eyeglasses. It is possible to walk around the system while gazing at its display volume to see a displayed object from a changing perspective, and multiple observers standing at different positions around the display can view the object simultaneously from their individual perspectives, as though the displayed object were a real 3D object. At the time of writing this article, only partial information on the design and principle of operation of the system was available. It is known that the system includes a high-speed, silicon-backplane, ferroelectric-liquid-crystal spatial light modulator (SLM), multiple high-power lasers for projecting images in multiple colors, a rotating helix that serves as a moving screen for displaying voxels [volume cells or volume elements, in analogy to pixels (picture cells or picture elements) in two-dimensional (2D) images], and a host computer. The rotating helix and its motor drive are the only moving parts. Under control by the host computer, a stream of 2D image patterns is generated on the SLM and projected through optics onto the surface of the rotating helix. The system utilizes a parallel pixel/voxel-addressing scheme: All the pixels of the 2D pattern on the SLM are addressed simultaneously by laser beams. This parallel addressing scheme overcomes the difficulty of achieving both high resolution and a high frame rate in a raster scanning or serial addressing scheme. It has been reported that the structure of the system is simple and easy to build, that the optical design and alignment are not difficult, and that the
Advances in three-dimensional diagnostic radiology
TER HAAR ROMENY, BART M.; ZUIDERVELD, KAREL J.; VAN WAES, PAUL F. G. M.; VAN WALSUM, THEO; VAN DER WEIJDEN, REMKO; WEICKERT, JOACHIM; STOKKING, RIK; WINK, ONNO; KALITZIN, STILIYAN; MAINTZ, TWAN; ZONNEVELD, FRANS; VIERGEVER, MAX A.
1998-01-01
The maturity of current 3D rendering software in combination with recent developments in computer vision techniques enable an exciting range of applications for the visualisation, measurement and interactive manipulation of volumetric data, relevant both for diagnostic imaging and for anatomy. This paper reviews recent work in this area from the Image Sciences Institute at Utrecht University. The processes that yield a useful visual presentation are sequential. After acquisition and before any visualisation, an essential step is to prepare the data properly: this field is known as ‘image processing’ or ‘computer vision’ in analogy with the processing in human vision. Examples will be discussed of modern image enhancement and denoising techniques, and the complex process of automatically finding the objects or regions of interest, i.e. segmentation. One of the newer and promising methodologies for image analysis is based on a mathematical analysis of the human (cortical) visual processing: multiscale image analysis. After preprocessing the 3D rendering can be acquired by simulating the ‘ray casting’ in the computer. New possibilities are presented, such as the integrated visualisation in one image of (accurately registered) datasets of the same patient acquired in different modality scanners. Other examples include colour coding of functional data such as SPECT brain perfusion or functional magnetic resonance (MR) data and even metric data such as skull thickness on the rendered 3D anatomy from MR or computed tomography (CT). Optimal use and perception of 3D visualisation in radiology requires fast display and truly interactive manipulation facilities. Modern and increasingly cheaper workstations (<$10000) allow this to be a reality. It is now possible to manipulate 3D images of 2563 at 15 frames per second interactively, placing virtual reality within reach. The possibilities of modern workstations become increasingly more sophisticated and versatile
NASA Astrophysics Data System (ADS)
Thalmann, Peter; Hieber, Simone E.; Schulz, Georg; Deyhle, Hans; Khimchenko, Anna; Kurtcuoglu, Vartan; Olgac, Ufuk; Marmaras, Anastasios; Kuo, Willy; Meyer, Eric P.; Beckmann, Felix; Herzen, Julia; Ehrbar, Stefanie; Müller, Bert
2014-09-01
Malfunction of oxygen regulation in kidney and liver may lead to the pathogenesis of chronic diseases. The underlying mechanisms are poorly understood. In kidney, it is hypothesized that renal gas shunting from arteries to veins eliminates excess oxygen. Such shunting is highly dependent on the structure of the renal vascular network. The vascular tree has so far not been quantified under maintenance of its connectivity as three-dimensional imaging of the vessel tree down to the smallest capillaries, which in mouse model are smaller than 5 μm in diameter, is a challenging task. An established protocol uses corrosion casts and applies synchrotron radiation-based micro-computed tomography (SRμCT), which provides the desired spatial resolution with the necessary contrast. However, SRμCT is expensive and beamtime access is limited. We show here that measurements with a phoenix nanotomrm (General Electric, Wunstorf, Germany) can provide comparable results to those obtained with SRμCT, except for regions with small vessel structures, where the signal-to-noise level was significantly reduced. For this purpose the nanotom®m measurement was compared with its corresponding measurement acquired at the beamline P05 at PETRA III at DESY, Hamburg, Germany.
Three-Dimensional Computational Fluid Dynamics
Haworth, D.C.; O'Rourke, P.J.; Ranganathan, R.
1998-09-01
Computational fluid dynamics (CFD) is one discipline falling under the broad heading of computer-aided engineering (CAE). CAE, together with computer-aided design (CAD) and computer-aided manufacturing (CAM), comprise a mathematical-based approach to engineering product and process design, analysis and fabrication. In this overview of CFD for the design engineer, our purposes are three-fold: (1) to define the scope of CFD and motivate its utility for engineering, (2) to provide a basic technical foundation for CFD, and (3) to convey how CFD is incorporated into engineering product and process design.
Computer program draws three-dimensional surfaces
NASA Technical Reports Server (NTRS)
Canright, R. B., Jr.; Swigert, P.
1972-01-01
Computer plotting program PLOT 3D draws views of surface forms z = f(x,y). Surface thus defined by program may be drawn after arbitrary rotations. Program portrays behavior of various functions involving two variables in many engineering, physics, and mathematical relationships.
Three-dimensional cardiac computational modelling: methods, features and applications.
Lopez-Perez, Alejandro; Sebastian, Rafael; Ferrero, Jose M
2015-01-01
The combination of computational models and biophysical simulations can help to interpret an array of experimental data and contribute to the understanding, diagnosis and treatment of complex diseases such as cardiac arrhythmias. For this reason, three-dimensional (3D) cardiac computational modelling is currently a rising field of research. The advance of medical imaging technology over the last decades has allowed the evolution from generic to patient-specific 3D cardiac models that faithfully represent the anatomy and different cardiac features of a given alive subject. Here we analyse sixty representative 3D cardiac computational models developed and published during the last fifty years, describing their information sources, features, development methods and online availability. This paper also reviews the necessary components to build a 3D computational model of the heart aimed at biophysical simulation, paying especial attention to cardiac electrophysiology (EP), and the existing approaches to incorporate those components. We assess the challenges associated to the different steps of the building process, from the processing of raw clinical or biological data to the final application, including image segmentation, inclusion of substructures and meshing among others. We briefly outline the personalisation approaches that are currently available in 3D cardiac computational modelling. Finally, we present examples of several specific applications, mainly related to cardiac EP simulation and model-based image analysis, showing the potential usefulness of 3D cardiac computational modelling into clinical environments as a tool to aid in the prevention, diagnosis and treatment of cardiac diseases. PMID:25928297
NASA Technical Reports Server (NTRS)
Anderson, B. H.
1983-01-01
A broad program to develop advanced, reliable, and user oriented three-dimensional viscous design techniques for supersonic inlet systems, and encourage their transfer into the general user community is discussed. Features of the program include: (1) develop effective methods of computing three-dimensional flows within a zonal modeling methodology; (2) ensure reasonable agreement between said analysis and selective sets of benchmark validation data; (3) develop user orientation into said analysis; and (4) explore and develop advanced numerical methodology.
High-definition three-dimensional television disparity map computation
NASA Astrophysics Data System (ADS)
Chammem, Afef; Mitrea, Mihai; Prêteux, Françoise
2012-10-01
By reconsidering some two-dimensional video inherited approaches and by adapting them to the stereoscopic video content and to the human visual system peculiarities, a new disparity map is designed. First, the inner relation between the left and the right views is modeled by some weights discriminating between the horizontal and vertical disparities. Second, the block matching operation is achieved by considering a visual related measure (normalized cross correlation) instead of the traditional pixel differences (mean squared error or sum of absolute differences). The advanced three-dimensional (3-D) video-new three step search (3DV-NTSS) disparity map (3-D Video-New Three Step Search) is benchmarked against two state-of-the-art algorithms, namely NTSS and full-search MPEG (FS-MPEG), by successively considering two corpora. The first corpus was organized during the 3DLive French national project and regroups 20 min of stereoscopic video sequences. The second one, with similar size, is provided by the MPEG community. The experimental results demonstrate the effectiveness of 3DV-NTSS in both reconstructed image quality (average gains between 3% and 7% in both PSNR and structural similarity, with a singular exception) and computational cost (search operation number reduced by average factors between 1.3 and 13). The 3DV-NTSS was finally validated by designing a watermarking method for high definition 3-D TV content protection.
New advances in three dimensional transient electromagnetic inversion
Newman, Gregory A.; Commer, Michael
2004-06-16
Inversion of transient electromagnetic (TEM) data sets to image the subsurface three-dimensional (3-D) electrical conductivity and magnetic permeability properties can be done directly in the time domain. The technique, first introduced by Wang et al. (1994) for causal and diffusive electromagnetic fields and subsequently implemented by Zhdanov and Portniaguine (1997) in the framework of iterative migration, is based upon imaging methods originally developed for seismic wavefields (Claerbout, 1971; Tarantola, 1984). In this paper we advance the original derivations of Wang et al. (1994) and Zhdanov and Portniaguine (1997) to treat non-causal TEM fields, as well as correct a flaw in the theory for treatment of magnetic field data. Our 3D imaging scheme is based on a conjugate-gradient search for the minimum of an error functional involving EM measurements governed by Maxwell's equations without displacement currents. Treatment for magnetic field, voltage (time derivative of the magnetic field) and electric field data are given. The functional can be computed by propagating the data errors back into the model in reverse time along with a DC field, sourced by the integrated data errors over the measurement time range. By correlating these fields, including the time-integrated back-propagated fields, with the corresponding incident field and its initial value at each image point, efficient computational forms for the gradients are developed. The forms of the gradients allow for additional efficiencies when voltage and electric field data are inverted. In such instances the combined data errors can be back-propagated jointly, significantly reducing the computation time required to solve the inverse problem. The inversion algorithm is applied to the long offset transient electromagnetic measurement (LOTEM) configuration thereby demonstrating its capability in inverting non-causal field measurements of electric field and voltage, sourced by a grounded wire, over complex
Three-dimensional surface reconstruction for industrial computed tomography
NASA Technical Reports Server (NTRS)
Vannier, M. W.; Knapp, R. H.; Gayou, D. E.; Sammon, N. P.; Butterfield, R. L.; Larson, J. W.
1985-01-01
Modern high resolution medical computed tomography (CT) scanners can produce geometrically accurate sectional images of many types of industrial objects. Computer software has been developed to convert serial CT scans into a three-dimensional surface form, suitable for display on the scanner itself. This software, originally developed for imaging the skull, has been adapted for application to industrial CT scanning, where serial CT scans thrrough an object of interest may be reconstructed to demonstrate spatial relationships in three dimensions that cannot be easily understood using the original slices. The methods of three-dimensional reconstruction and solid modeling are reviewed, and reconstruction in three dimensions from CT scans through familiar objects is demonstrated.
Ultrafast three-dimensional x-ray computed tomography
Bieberle, Martina; Barthel, Frank; Hampel, Uwe; Menz, Hans-Juergen; Mayer, Hans-Georg
2011-01-17
X-ray computed tomography (CT) is a well established visualization technique in medicine and nondestructive testing. However, since CT scanning requires sampling of radiographic projections from different viewing angles, common CT systems with mechanically moving parts are too slow for dynamic imaging, for instance of multiphase flows or live animals. Here, we introduce an ultrafast three-dimensional x-ray CT method based on electron beam scanning, which achieves volume rates of 500 s{sup -1}. Primary experiments revealed the capability of this method to recover the structure of phase boundaries in gas-solid and gas-liquid two-phase flows, which undergo three-dimensional structural changes in the millisecond scale.
Three-dimensional computed tomography of the carpal ligaments.
Nanno, Mitsuhiko; Viegas, Steven F
2009-03-01
This article details a current perspective and accurate anatomical three-dimensional descriptions of the ligaments of the wrist. The carpometacarpal ligaments, the intercarpal ligaments, and the radiocarpal ligaments are described and illustrated using a unique combination of detailed dissection, computed tomography, and a three-dimensional digitization technique. Detailed information is also provided about the ligamentous attachments of the carpometacarpal joints, the carpal bones, and the distal radius. This study improves knowledge and understanding of the normal anatomy and mechanics of the radiocarpal and intercarpal ligaments and the carpometacarpal joints, and it should help in the assessment of radiographic images and treatment of various injuries and degenerative changes seen in the wrist. The knowledge of the ligaments will further serve as a foundation for understanding the anatomy of the ligaments, the biomechanics of the wrist, and the function of the individual ligaments and their roles in joint motion and stability. PMID:19235667
Ultrafast three-dimensional x-ray computed tomography
NASA Astrophysics Data System (ADS)
Bieberle, Martina; Barthel, Frank; Menz, Hans-Jürgen; Mayer, Hans-Georg; Hampel, Uwe
2011-01-01
X-ray computed tomography (CT) is a well established visualization technique in medicine and nondestructive testing. However, since CT scanning requires sampling of radiographic projections from different viewing angles, common CT systems with mechanically moving parts are too slow for dynamic imaging, for instance of multiphase flows or live animals. Here, we introduce an ultrafast three-dimensional x-ray CT method based on electron beam scanning, which achieves volume rates of 500 s-1. Primary experiments revealed the capability of this method to recover the structure of phase boundaries in gas-solid and gas-liquid two-phase flows, which undergo three-dimensional structural changes in the millisecond scale.
Comparison of two three-dimensional cephalometric analysis computer software
Sawchuk, Dena; Alhadlaq, Adel; Alkhadra, Thamer; Carlyle, Terry D; Kusnoto, Budi; El-Bialy, Tarek
2014-01-01
Background: Three-dimensional cephalometric analyses are getting more attraction in orthodontics. The aim of this study was to compare two softwares to evaluate three-dimensional cephalometric analyses of orthodontic treatment outcomes. Materials and Methods: Twenty cone beam computed tomography images were obtained using i-CAT® imaging system from patient's records as part of their regular orthodontic records. The images were analyzed using InVivoDental5.0 (Anatomage Inc.) and 3DCeph™ (University of Illinois at Chicago, Chicago, IL, USA) software. Before and after orthodontic treatments data were analyzed using t-test. Results: Reliability test using interclass correlation coefficient was stronger for InVivoDental5.0 (0.83-0.98) compared with 3DCeph™ (0.51-0.90). Paired t-test comparison of the two softwares shows no statistical significant difference in the measurements made in the two softwares. Conclusions: InVivoDental5.0 measurements are more reproducible and user friendly when compared to 3DCeph™. No statistical difference between the two softwares in linear or angular measurements. 3DCeph™ is more time-consuming in performing three-dimensional analysis compared with InVivoDental5.0. PMID:25426454
Three-dimensional geospatial information service based on cloud computing
NASA Astrophysics Data System (ADS)
Zhai, Xi; Yue, Peng; Jiang, Liangcun; Wang, Linnan
2014-01-01
Cloud computing technologies can support high-performance geospatial services in various domains, such as smart city and agriculture. Apache Hadoop, an open-source software framework, can be used to build a cloud environment on commodity clusters for storage and large-scale processing of data sets. The Open Geospatial Consortium (OGC) Web 3-D Service (W3DS) is a portrayal service for three-dimensional (3-D) geospatial data. Its performance could be improved by cloud computing technologies. This paper investigates how OGC W3DS could be developed in a cloud computing environment. It adopts the Apache Hadoop as the framework to provide a cloud implementation. The design and implementation of the 3-D geospatial information cloud service is presented. The performance evaluation is performed over data retrieval tests running in a cloud platform built by Hadoop clusters. The evaluation results provide a valuable reference on providing high-performance 3-D geospatial information cloud services.
Three-dimensional holographic reconstruction from computational tomography images
NASA Astrophysics Data System (ADS)
Zhao, Yan; Cao, Liangcai; Zhang, Hao; He, Qingsheng; Jin, Guofan
2014-11-01
An angular spectrum holographic algorithm is proposed for generating three-dimensional (3D) reconstruction from multiple computational tomography (CT) slices. Objects consist of multiple slices can be easily modeled by the angular spectrum. So the 3D structure can be built through the superposition of computer generated phase holograms originally from parallel discrete planes at different depths. Then the superposed phase hologram is uploaded to the phase-only spatial light modulator (SLM). With the SLM illuminated by the coherent light, the 3D reconstruction is observed by a camera. The proposed method is more computationally efficient compared with the point source algorithm, and the angular spectrum holographic algorithm can process more large-capacity CT data for the 3D visualization. Experiment demonstrates the feasibility of reconstructing CT biological structure with holographic display.
New advances in three-dimensional controlled-sourceelectromagnetic inversion
Commer, Michael; Newman, Gregory A.
2007-05-19
New techniques for improving both the computational andimaging performance of the three dimensional (3D) electromagnetic inverseproblem are presented. A non-linear conjugate gradient algorithm is theframework of the inversion scheme. Full wave equation modelling forcontrolled sources is utilized for data simulation along with anefficient gradient computation approach for the model update. Improvingthe modelling efficiency of the 3D finite difference method involves theseparation of the potentially large modelling mesh, defining the set ofmodel parameters, from the computational finite difference meshes usedfor field simulation. Grid spacings and thus overall grid sizes can bereduced and optimized according to source frequencies and source-receiveroffsets of a given input data set. Further computational efficiency isobtained by combining different levels of parallelization. While theparallel scheme allows for an arbitrarily large number of parallel tasks,the relative amount of message passing is kept constant. Imageenhancement is achieved by model parameter transformation functions,which enforce bounded conductivity parameters and thus prevent parameterovershoots. Further, a remedy for treating distorted data within theinversion process is presented. Data distortions simulated here includepositioning errors and a highly conductive overburden, hiding the desiredtarget signal. The methods are demonstrated using both synthetic andfield data.
Advanced three-dimensional Eulerian hydrodynamic algorithm development
Rider, W.J.; Kothe, D.B.; Mosso, S.
1998-11-01
This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The purpose of this project is to investigate, implement, and evaluate algorithms that have high potential for improving the robustness, fidelity and accuracy of three-dimensional Eulerian hydrodynamic simulations. Eulerian computations are necessary to simulate a number of important physical phenomena ranging from the molding process for metal parts to nuclear weapons safety issues to astrophysical phenomena such as that associated with a Type 2 supernovae. A number of algorithmic issues were explored in the course of this research including interface/volume tracking, surface physics integration, high resolution integration techniques, multilevel iterative methods, multimaterial hydrodynamics and coupling radiation with hydrodynamics. This project combines core strengths of several Laboratory divisions. The project has high institutional benefit given the renewed emphasis on numerical simulations in Science-Based Stockpile Stewardship and the Accelerated Strategic Computing Initiative and LANL`s tactical goals related to high performance computing and simulation.
A three-dimensional magnetostatics computer code for insertion devices.
Chubar, O; Elleaume, P; Chavanne, J
1998-05-01
RADIA is a three-dimensional magnetostatics computer code optimized for the design of undulators and wigglers. It solves boundary magnetostatics problems with magnetized and current-carrying volumes using the boundary integral approach. The magnetized volumes can be arbitrary polyhedrons with non-linear (iron) or linear anisotropic (permanent magnet) characteristics. The current-carrying elements can be straight or curved blocks with rectangular cross sections. Boundary conditions are simulated by the technique of mirroring. Analytical formulae used for the computation of the field produced by a magnetized volume of a polyhedron shape are detailed. The RADIA code is written in object-oriented C++ and interfaced to Mathematica [Mathematica is a registered trademark of Wolfram Research, Inc.]. The code outperforms currently available finite-element packages with respect to the CPU time of the solver and accuracy of the field integral estimations. An application of the code to the case of a wedge-pole undulator is presented. PMID:15263552
Three Dimensional Display Of Tumors Via Computed Tomography
NASA Astrophysics Data System (ADS)
Smathers, Ralph L.
1985-09-01
Computed tomography is widely utilized for the detection and staging of neoplasm. Typical chest, abdomen or pelvis CT scans may produce 10 to 20 transverse slices for each region. The mental reconstruction of the three dimensional anatomy from these transverse sections can be done by a physician who has had training in the analysis and interpretation of cross sectional anatomy and pathology. This mental reconstruction, however, may take years to develop into an efficient tool. With the 3-D reconstructions used in this study, diagnostic information concerning the location, shape and spread of tumor masses can be presented in a simple, intuitive 3-dimensional display. This technique has been found to be useful for improving communication between diagnostic radiologists and consulting physicians.
Advancing three-dimensional MEMS by complimentary laser micro manufacturing
NASA Astrophysics Data System (ADS)
Palmer, Jeremy A.; Williams, John D.; Lemp, Tom; Lehecka, Tom M.; Medina, Francisco; Wicker, Ryan B.
2006-01-01
This paper describes improvements that enable engineers to create three-dimensional MEMS in a variety of materials. It also provides a means for selectively adding three-dimensional, high aspect ratio features to pre-existing PMMA micro molds for subsequent LIGA processing. This complimentary method involves in situ construction of three-dimensional micro molds in a stand-alone configuration or directly adjacent to features formed by x-ray lithography. Three-dimensional micro molds are created by micro stereolithography (MSL), an additive rapid prototyping technology. Alternatively, three-dimensional features may be added by direct femtosecond laser micro machining. Parameters for optimal femtosecond laser micro machining of PMMA at 800 nanometers are presented. The technical discussion also includes strategies for enhancements in the context of material selection and post-process surface finish. This approach may lead to practical, cost-effective 3-D MEMS with the surface finish and throughput advantages of x-ray lithography. Accurate three-dimensional metal microstructures are demonstrated. Challenges remain in process planning for micro stereolithography and development of buried features following femtosecond laser micro machining.
Computations of Complex Three-Dimensional Turbulent Free Jets
NASA Technical Reports Server (NTRS)
Wilson, Robert V.; Demuren, Ayodeji O.
1997-01-01
Three-dimensional, incompressible turbulent jets with rectangular and elliptical cross-sections are simulated with a finite-difference numerical method. The full Navier- Stokes equations are solved at low Reynolds numbers, whereas at high Reynolds numbers filtered forms of the equations are solved along with a sub-grid scale model to approximate the effects of the unresolved scales. A 2-N storage, third-order Runge-Kutta scheme is used for temporary discretization and a fourth-order compact scheme is used for spatial discretization. Although such methods are widely used in the simulation of compressible flows, the lack of an evolution equation for pressure or density presents particular difficulty in incompressible flows. The pressure-velocity coupling must be established indirectly. It is achieved, in this study, through a Poisson equation which is solved by a compact scheme of the same order of accuracy. The numerical formulation is validated and the dispersion and dissipation errors are documented by the solution of a wide range of benchmark problems. Three-dimensional computations are performed for different inlet conditions which model the naturally developing and forced jets. The experimentally observed phenomenon of axis-switching is captured in the numerical simulation, and it is confirmed through flow visualization that this is based on self-induction of the vorticity field. Statistical quantities such as mean velocity, mean pressure, two-point velocity spatial correlations and Reynolds stresses are presented. Detailed budgets of the mean momentum and Reynolds stresses are presented. Detailed budgets of the mean momentum and Reynolds stress equations are presented to aid in the turbulence modeling of complex jets. Simulations of circular jets are used to quantify the effect of the non-uniform curvature of the non-circular jets.
Three-dimensional computer modeling of hydrogen injection and combustion
Johnson, N.L.; Amsden, A.A.; Naber, J.D.; Siebers, D.L.
1995-02-01
The hydrodynamics of hydrogen gas injection into a fixed-volume combustion chamber is analyzed and simulated using KIVA-3, a three-dimensional, reactive flow computer code. Comparisons of the simulation results are made to data obtained at the Combustion Research Facility at Sandia National Laboratory-California (SNL-CA). Simulation of the gas injection problem is found to be of comparable difficulty as the liquid fuel injection in diesel engines. The primary challenge is the large change of length scale from the flow of gas in the orifice to the penetration in the combustion chamber. In the current experiments, the change of length scale is about 4,000. A reduction of the full problem is developed that reduces the change in length scale in the simulation to about 400, with a comparable improvement in computational times. Comparisons of the simulation to the experimental data shows good agreement in the penetration history and pressure rise in the combustion chamber. At late times the comparison is sensitive to the method of determination of the penetration in the simulations. In a comparison of the combustion modeling of methane and hydrogen, hydrogen combustion is more difficult to model, and currently available kinetic models fail to predict the observed autoignition delay at these conditions.
Three-Dimensional Radiative Transfer on a Massively Parallel Computer.
NASA Astrophysics Data System (ADS)
Vath, Horst Michael
1994-01-01
We perform three-dimensional radiative transfer calculations on the MasPar MP-1, which contains 8192 processors and is a single instruction multiple data (SIMD) machine, an example of the new generation of massively parallel computers. To make radiative transfer calculations efficient, we must re-consider the numerical methods and methods of storage of data that have been used with serial machines. We developed a numerical code which efficiently calculates images and spectra of astrophysical systems as seen from different viewing directions and at different wavelengths. We use this code to examine a number of different astrophysical systems. First we image the HI distribution of model galaxies. Then we investigate the galaxy NGC 5055, which displays a radial asymmetry in its optical appearance. This can be explained by the presence of dust in the outer HI disk far beyond the optical disk. As the formation of dust is connected to the presence of stars, the existence of dust in outer regions of this galaxy could have consequences for star formation at a time when this galaxy was just forming. Next we use the code for polarized radiative transfer. We first discuss the numerical computation of the required cyclotron opacities and use them to calculate spectra of AM Her systems, binaries containing accreting magnetic white dwarfs. Then we obtain spectra of an extended polar cap. Previous calculations did not consider the three -dimensional extension of the shock. We find that this results in a significant underestimate of the radiation emitted in the shock. Next we calculate the spectrum of the intermediate polar RE 0751+14. For this system we obtain a magnetic field of ~10 MG, which has consequences for the evolution of intermediate polars. Finally we perform 3D radiative transfer in NLTE in the two-level atom approximation. To solve the transfer equation in this case, we adapt the short characteristic method and examine different acceleration methods to obtain the
A Three-Dimensional Computational Model of Collagen Network Mechanics
Lee, Byoungkoo; Zhou, Xin; Riching, Kristin; Eliceiri, Kevin W.; Keely, Patricia J.; Guelcher, Scott A.; Weaver, Alissa M.; Jiang, Yi
2014-01-01
Extracellular matrix (ECM) strongly influences cellular behaviors, including cell proliferation, adhesion, and particularly migration. In cancer, the rigidity of the stromal collagen environment is thought to control tumor aggressiveness, and collagen alignment has been linked to tumor cell invasion. While the mechanical properties of collagen at both the single fiber scale and the bulk gel scale are quite well studied, how the fiber network responds to local stress or deformation, both structurally and mechanically, is poorly understood. This intermediate scale knowledge is important to understanding cell-ECM interactions and is the focus of this study. We have developed a three-dimensional elastic collagen fiber network model (bead-and-spring model) and studied fiber network behaviors for various biophysical conditions: collagen density, crosslinker strength, crosslinker density, and fiber orientation (random vs. prealigned). We found the best-fit crosslinker parameter values using shear simulation tests in a small strain region. Using this calibrated collagen model, we simulated both shear and tensile tests in a large linear strain region for different network geometry conditions. The results suggest that network geometry is a key determinant of the mechanical properties of the fiber network. We further demonstrated how the fiber network structure and mechanics evolves with a local formation, mimicking the effect of pulling by a pseudopod during cell migration. Our computational fiber network model is a step toward a full biomechanical model of cellular behaviors in various ECM conditions. PMID:25386649
Computer simulations of realistic three-dimensional microstructures
NASA Astrophysics Data System (ADS)
Mao, Yuxiong
A novel and efficient methodology is developed for computer simulations of realistic two-dimensional (2D) and three-dimensional (3D) microstructures. The simulations incorporate realistic 2D and 3D complex morphologies/shapes, spatial patterns, anisotropy, volume fractions, and size distributions of the microstructural features statistically similar to those in the corresponding real microstructures. The methodology permits simulations of sufficiently large 2D as well as 3D microstructural windows that incorporate short-range (on the order of particle/feature size) as well as long-range (hundred times the particle/feature size) microstructural heterogeneities and spatial patterns at high resolution. The utility of the technique has been successfully demonstrated through its application to the 2D microstructures of the constituent particles in wrought Al-alloys, the 3D microstructure of discontinuously reinforced Al-alloy (DRA) composites containing SiC particles that have complex 3D shapes/morphologies and spatial clustering, and 3D microstructure of boron modified Ti-6Al-4V composites containing fine TiB whiskers and coarse primary TiB particles. The simulation parameters are correlated with the materials processing parameters (such as composition, particle size ratio, extrusion ratio, extrusion temperature, etc.), which enables the simulations of rational virtual 3D microstructures for the parametric studies on microstructure-properties relationships. The simulated microstructures have been implemented in the 3D finite-elements (FE)-based framework for simulations of micro-mechanical response and stress-strain curves. Finally, a new unbiased and assumption free dual-scale virtual cycloids probe for estimating surface area of 3D objects constructed by 2D serial section images is also presented.
Computer vision system for three-dimensional inspection
NASA Astrophysics Data System (ADS)
Penafiel, Francisco; Fernandez, Luis; Campoy, Pascual; Aracil, Rafael
1994-11-01
In the manufacturing process certain workpieces are inspected for dimensional measurement using sophisticated quality control techniques. During the operation phase, these parts are deformed due to the high temperatures involved in the process. The evolution of the workpieces structure is noticed on their dimensional modification. This evolution can be measured with a set of dimensional parameters. In this paper, a three dimensional automatic inspection of these parts is proposed. The aim is the measuring of some workpieces features through 3D control methods using directional lighting and a computer artificial vision system. The results of this measuring must be compared with the parameters obtained after the manufacturing process in order to determine the degree of deformation of the workpiece and decide whether it is still usable or not. Workpieces outside a predetermined specification range must be discarded and replaced by new ones. The advantage of artificial vision methods is based on the fact that there is no need to get in touch with the object to inspect. This makes feasible its use in hazardous environments, not suitable for human beings. A system has been developed and applied to the inspection of fuel assemblies in nuclear power plants. Such a system has been implemented in a very high level of radiation environment and operates in underwater conditions. The physical dimensions of a nuclear fuel assembly are modified after its operation in a nuclear power plant in relation to the original dimensions after its manufacturing. The whole system (camera, mechanical and illumination systems and the radioactive fuel assembly) is submerged in water for minimizing radiation effects and is remotely controlled by human intervention. The developed system has to inspect accurately a set of measures on the fuel assembly surface such as length, twists, arching, etc. The present project called SICOM (nuclear fuel assembly inspection system) is included into the R
Method for computing three-dimensional turbulent flows
Bernard, P.S.; Berger, B.S.
1982-06-01
The MVC (mean vorticity and covariance) turbulence closure is derived for three-dimensional turbulent flows. The derivation utilizes Lagrangian time expansion techniques applied to the unclosed terms of the mean vorticity and covariance equations. The closed mean vorticity equation is applied to the numerical solution of fully developed three-dimensional channel flow. Anisotropies in the wall region are modelled by pairs of counterrotating streamwise vortices. The numerical results are in close agreement with experimental data. Analysis of the contributions of the terms in the mean vorticity equation gives insight into the dynamics of the turbulent boundary. 41 references, 7 figures.
Application of three-dimensional computed tomography in craniofacial clinical practice and research.
Anderson, P J; Yong, R; Surman, T L; Rajion, Z A; Ranjitkar, S
2014-06-01
Following the invention of the first computed tomography (CT) scanner in the early 1970s, many innovations in three-dimensional (3D) diagnostic imaging technology have occurred, leading to a wide range of applications in craniofacial clinical practice and research. Three-dimensional image analysis provides superior and more detailed information compared with conventional plain two-dimensional (2D) radiography, with the added benefit of 3D printing for preoperative treatment planning and regenerative therapy. Current state-of-the-art multidetector CT (MDCT), also known as medical CT, has an important role in the diagnosis and management of craniofacial injuries and pathology. Three-dimensional cone beam CT (CBCT), pioneered in the 1990s, is gaining increasing popularity in dental and craniofacial clinical practice because of its faster image acquisition at a lower radiation dose, but sound guidelines are needed to ensure its optimal clinical use. Recent innovations in micro-computed tomography (micro-CT) have revolutionized craniofacial biology research by enabling higher resolution scanning of teeth beyond the capabilities of MDCT and CBCT, presenting new prospects for translational clinical research. Even after four decades of refinement, CT technology continues to advance and broaden the horizons of craniofacial clinical practice and phenomics research. PMID:24611727
Three-dimensional hybrid grid generation using advancing front techniques
NASA Technical Reports Server (NTRS)
Steinbrenner, John P.; Noack, Ralph W.
1995-01-01
A new 3-dimensional hybrid grid generation technique has been developed, based on ideas of advancing fronts for both structured and unstructured grids. In this approach, structured grids are first generate independently around individual components of the geometry. Fronts are initialized on these structure grids, and advanced outward so that new cells are extracted directly from the structured grids. Employing typical advancing front techniques, cells are rejected if they intersect the existing front or fail other criteria When no more viable structured cells exist further cells are advanced in an unstructured manner to close off the overall domain, resulting in a grid of 'hybrid' form. There are two primary advantages to the hybrid formulation. First, generating blocks with limited regard to topology eliminates the bottleneck encountered when a multiple block system is used to fully encapsulate a domain. Individual blocks may be generated free of external constraints, which will significantly reduce the generation time. Secondly, grid points near the body (presumably with high aspect ratio) will still maintain a structured (non-triangular or tetrahedral) character, thereby maximizing grid quality and solution accuracy near the surface.
Computation of three-dimensional mixed convective boundary layer flow
NASA Technical Reports Server (NTRS)
Gadepalli, Prashandt; Rahman, Muhammad M.
1995-01-01
The paper presents the numerical solution of heat and mass transfer during cross-flow (orthogonal) mixed convection. In this class of flow, a buoyancy-driven transport in the vertical direction and a forced convective flow in the horizontal direction results in a three-dimensional boundary layer structure adjacent to the plate. The rates of heat and mass transfer are determined by a combined influence of the two transport processes. The equations for the conservation of mass, momentum, energy, and species concentration were solved along with appropriate boundary conditions to determine the distributions of velocity components, temperature, and concentration across the thickness of the boundary layer at different locations on the plate. Results were expressed in dimensionless form using Reynolds number, Richardson number for heat transfer, Richardson number for mass transfer, Prandtl number, and Schmidt number as parameters. It was found that the transport is dominated by buoyancy at smaller vertical locations and at larger distances away from the forced convection leading edge. Effects of forced convection appeared to be very strong at smaller horizontal distances from the leading edge. The cross stream forced convection enhanced the rate of heat and mass transfer by a very significant amount.
NASA Technical Reports Server (NTRS)
Pan, Y. S.
1978-01-01
A three dimensional, partially elliptic, computer program was developed. Without requiring three dimensional computer storage locations for all flow variables, the partially elliptic program is capable of predicting three dimensional combustor flow fields with large downstream effects. The program requires only slight increase of computer storage over the parabolic flow program from which it was developed. A finite difference formulation for a three dimensional, fully elliptic, turbulent, reacting, flow field was derived. Because of the negligible diffusion effects in the main flow direction in a supersonic combustor, the set of finite-difference equations can be reduced to a partially elliptic form. Only the pressure field was governed by an elliptic equation and requires three dimensional storage; all other dependent variables are governed by parabolic equations. A numerical procedure which combines a marching integration scheme with an iterative scheme for solving the elliptic pressure was adopted.
Parallel computation of three-dimensional nonlinear magnetostatic problems.
Levine, D.; Gropp, W.; Forsman, K.; Kettunen, L.; Mathematics and Computer Science; Tampere Univ. of Tech.
1999-02-01
We describe a general-purpose parallel electromagnetic code for computing accurate solutions to large computationally demanding, 3D, nonlinear magnetostatic problems. The code, CORAL, is based on a volume integral equation formulation. Using an IBM SP parallel computer and iterative solution methods, we successfully solved the dense linear systems inherent in such formulations. A key component of our work was the use of the PETSc library, which provides parallel portability and access to the latest linear algebra solution technology.
Children Learning from Artfully Designed, Three-Dimensional Computer Animation
ERIC Educational Resources Information Center
Ju, Yoomi Choi; Cifuentes, Lauren
2002-01-01
An artfully designed, 3-D computer-generated video story was created to demonstrate the mixing of primary colors to obtain secondary colors. Two research questions were explored in this research: Do artfully designed 3-D computer-generated video stories enhance learning or are such entertaining works a distraction from learning? And, do children…
The three-dimensional Multi-Block Advanced Grid Generation System (3DMAGGS)
NASA Technical Reports Server (NTRS)
Alter, Stephen J.; Weilmuenster, Kenneth J.
1993-01-01
As the size and complexity of three dimensional volume grids increases, there is a growing need for fast and efficient 3D volumetric elliptic grid solvers. Present day solvers are limited by computational speed and do not have all the capabilities such as interior volume grid clustering control, viscous grid clustering at the wall of a configuration, truncation error limiters, and convergence optimization residing in one code. A new volume grid generator, 3DMAGGS (Three-Dimensional Multi-Block Advanced Grid Generation System), which is based on the 3DGRAPE code, has evolved to meet these needs. This is a manual for the usage of 3DMAGGS and contains five sections, including the motivations and usage, a GRIDGEN interface, a grid quality analysis tool, a sample case for verifying correct operation of the code, and a comparison to both 3DGRAPE and GRIDGEN3D. Since it was derived from 3DGRAPE, this technical memorandum should be used in conjunction with the 3DGRAPE manual (NASA TM-102224).
Early changes in condylar position after mandibular advancement: a three-dimensional analysis.
Méndez-Manjón, I; Guijarro-Martínez, R; Valls-Ontañón, A; Hernández-Alfaro, F
2016-06-01
The aim of this study was to perform a three-dimensional (3D) assessment of positional changes of the mandibular condyle after bilateral sagittal split osteotomy (BSSO). A prospective evaluation of 22 skeletal class II patients who underwent a BSSO for mandibular advancement was performed. Pre- and postoperative cone beam computed tomography scans were taken. Using the cranial base as a stable reference, the pre- and postoperative 3D skull models were superimposed virtually. Positional changes of the condyles were assessed with a 3D colour mapping system (SimPlant O&O). A Brunner-Langer statistical test was applied to test the null hypothesis that the condylar position remains stable after BSSO. The level of significance was set at 0.05. The mean mandibular advancement in the studied sample was 6.7±1.6mm. Overall, the condylar positional changes after BSSO for mandibular advancement were statistically significant (P<0.05). A positive correlation was found between the displacement of the left condyle and the amount of mandibular advancement (P<0.01). The results of this study suggest that statistically significant changes of condylar position occur after mandibular advancement. Long-term evaluation is needed to assess the capacity of the temporomandibular joint to adapt to these changes. PMID:26837717
Computation of three-dimensional flows using two stream functions
NASA Technical Reports Server (NTRS)
Greywall, Mahesh S.
1991-01-01
An approach to compute 3-D flows using two stream functions is presented. The method generates a boundary fitted grid as part of its solution. Commonly used two steps for computing the flow fields are combined into a single step in the present approach: (1) boundary fitted grid generation; and (2) solution of Navier-Stokes equations on the generated grid. The presented method can be used to directly compute 3-D viscous flows, or the potential flow approximation of this method can be used to generate grids for other algorithms to compute 3-D viscous flows. The independent variables used are chi, a spatial coordinate, and xi and eta, values of stream functions along two sets of suitably chosen intersecting stream surfaces. The dependent variables used are the streamwise velocity, and two functions that describe the stream surfaces. Since for a 3-D flow there is no unique way to define two sets of intersecting stream surfaces to cover the given flow, different types of two sets of intersecting stream surfaces are considered. First, the metric of the (chi, xi, eta) curvilinear coordinate system associated with each type is presented. Next, equations for the steady state transport of mass, momentum, and energy are presented in terms of the metric of the (chi, xi, eta) coordinate system. Also included are the inviscid and the parabolized approximations to the general transport equations.
NASA Technical Reports Server (NTRS)
Ross, Muriel D.; Chimento, Thomas; Doshay, David; Cheng, Rei
1992-01-01
Results of computer-assisted research concerned with the three-dimensional reconstruction and simulations of vestibular macular neural connectivities are summarized. The discussion focuses on terminal/receptive fields, the question of synapses across the striola, endoplasmic reticulum and its potential role in macular information processing, and the inner epithelial plexus. Also included are preliminary results of computer simulations of nerve fiber collateral functioning, an essential step toward the three-dimensional simulation of a functioning macular neural network.
NASA Astrophysics Data System (ADS)
Wang, Dongdong; Liang, Qingwen; Zhang, Hanjie
2016-06-01
A superconvergent isogeometric formulation is presented to compute the eigenvalues for three dimensional wave equation. This three dimensional superconvergent isogeometric formulation is characterized by a higher order mass matrix formulation with particular reference to the quadratic basis functions. The three dimensional higher order mass matrix is built upon an optimal combination of the reduced bandwidth mass matrix and the consistent mass matrix. The frequency error associated with the isogeometric discretization of three dimensional wave equation is derived in detail. In particular, the optimal mass combination parameter for higher order mass matrix is devised as a function of the two spatial wave propagation angles, which enables that arbitrary frequency corresponding to a given wave propagation direction can be computed in a superconvergent way. Two extra orders of accuracy, i.e., 6th order of accuracy, are attained by the proposed higher order mass matrix than the consistent mass matrix for the frequency computation of three dimensional wave equation. The dispersion property of the present three dimensional higher order mass matrix formulation is examined as well. The accuracy of the proposed three dimensional superconvergent isogeometric formulation is testified by several numerical examples.
Computation of three-dimensional flow about aerobrake configurations
NASA Technical Reports Server (NTRS)
Li, C. P.
1986-01-01
Ellipsoid, cone and cylinder aerobrake configurations are analyzed to provide comparison data between experimental and model predictions. An analytical model was devised to account for the shock layer ahead of the body and in the near-wake region in terms of the Navier-Stokes equations expressed in conformal polar and azimuthal-angle coordinates. Using polar coordinates simplified the equations by mapping the body onto a sphere, a procedure which also reduced the magnitude of the discretization errors. The equations are then solved using an alternating direction implicit (ADI) factorization technique. Computations were carried out for Mach 3-10 at various grid resolutions and compared with available wind tunnel data. The model generated pressure distributions, heat transfer coefficients and velocity profile data that agreed relatively well with experimental data at a reduced computational cost. Further work is necessary to identify the location of shocks and to model flows about asymmetric configurations.
Numerical procedures for three-dimensional computational surface thermochemistry
NASA Technical Reports Server (NTRS)
Milos, Frank S.; Rasky, Daniel J.
1992-01-01
Models and equations for surface thermochemistry and near-surface thermophysics of aerodynamically-heated thermal protection materials are reviewed, with particular emphasis on computational boundary conditions for surface mass and energy transfer. The surface energy and mass balances, coupled with an appropriate ablation or surface catalysis model, provide complete thermochemical boundary conditions for a true multidisciplinary solution of the fully coupled fluid-dynamics/solid mechanics problem. Practical approximate solutions can be obtained by using a detailed model with full thermophysics for either the solid or fluid phase amd a semianalytic method for the other half of the problem. A significant increase in the state-of-the-art in aerothermal computational fluid dynamics is possible by uniting CFD methodology with surface thermochemistry boundary conditions and the heat-balance-integral method.
Owen, Benjamin; Lowe, Christopher; Ashton, Neil; Mandal, Parthasarathi; Rogers, Steven; Wein, Wolfgang; McCollum, Charles; Revell, Alistair
2016-03-01
The current criterion for surgical intervention in abdominal aortic aneurysms, based upon a maximal aortic diameter, is considered conservative due to the high mortality rate in case of rupture. The research community is actively investigating the use of computational mechanics tools combined with patient-specific imaging to help identify more accurate criteria. Widespread uptake of a successful metric will however be limited by the need for computed tomography, which is at present the primary image extraction method on account of the location and complex shape of the aneurysms. The use of three-dimensional ultrasound as the scanning method is more attractive on account of increased availability, reduced cost and reduced risk to patients. The suitability of three-dimensional ultrasound is assessed for this purpose in the present work; computational fluid dynamics simulations were performed on geometries obtained from the same patient using both ultrasound and computed tomography. The influence of different smoothing algorithms is investigated in the geometry preparation stage and Taubin's low-pass filter was found to best preserve geometry features. Laminar, Newtonian, steady-state simulation analysis identified haemodynamic characteristics to be qualitatively similar in terms of wall shear stress, velocity and vorticity. The study demonstrates the potential for three-dimensional ultrasound to be integrated into a more accessible patient-specific modelling tool able to identify the need for surgical intervention of abdominal aortic aneurysms. PMID:26893226
Computational Model of Three Dimensional Elastic Wing Driven by Muscles
NASA Astrophysics Data System (ADS)
Wang, Z. Jane; Cowen, Nathaniel; Peskin, Charles S.; Childress, Stephen W.
2003-11-01
The flapping wing motion observed in nature results from couplings of muscles, flexible wing structures, and unsteady flows. Previously we have studied the unsteady flows and forces of a rigid two dimensional wing undergoing prescribed motion similar to kinematics observed in insects, as a means of understanding basic unsteady aerodynamic mechanisms. In this talk, we describe our recent progress in constructing a more realistic model insect, which consists of a pair of elastic wings immersed in fluids, and is driven by periodically contracting 'muscles'. A natural computational framework for such a system is the immersed boundary method, which is used here. We present simulations of flapping flight at Reynolds number 10^2, in the same range as that of fruitflies and butterflies.
Hydrogen program combustion research: Three dimensional computational modeling
Johnson, N.L.; Amsden, A.A.; Butler, T.D.
1995-05-01
We have significantly increased our computational modeling capability by the addition of a vertical valve model in KIVA-3, code used internationally for engine design. In this report the implementation and application of the valve model is described. The model is shown to reproduce the experimentally verified intake flow problem examined by Hessel. Furthermore, the sensitivity and performance of the model is examined for the geometry and conditions of the hydrogen-fueled Onan engine in development at Sandia National Laboratory. Overall the valve model is shown to have comparable accuracy as the general flow simulation capability in KIVA-3, which has been well validated by past comparisons to experiments. In the exploratory simulations of the Onan engine, the standard use of the single kinetic reaction for hydrogen oxidation was found to be inadequate for modeling the hydrogen combustion because of its inability to describe both the observed laminar flame speed and the absence of autoignition in the Onan engine. We propose a temporary solution that inhibits the autoignition without sacrificing the ability to model spark ignition. In the absence of experimental data on the Onan engine, a computational investigation was undertaken to evaluate the importance of modeling the intake flow on the combustion and NO{sub x} emissions. A simulation that began with the compression of a quiescent hydrogen-air mixture was compared to a simulation of the full induction process with resolved opening and closing of the intake valve. Although minor differences were observed in the cylinder-averaged pressure, temperature, bulk-flow kinetic energy and turbulent kinetic energy, large differences where observed in the hydrogen combustion rate and NO{sub x} emissions. The flow state at combustion is highly heterogeneous and sensitive to the details of the bulk and turbulent flow and that an accurate simulation of the Onan engine must include the modeling of the air-fuel induction.
Three Dimensional Computer Graphics Federates for the 2012 Smackdown Simulation
NASA Technical Reports Server (NTRS)
Fordyce, Crystal; Govindaiah, Swetha; Muratet, Sean; O'Neil, Daniel A.; Schricker, Bradley C.
2012-01-01
The Simulation Interoperability Standards Organization (SISO) Smackdown is a two-year old annual event held at the 2012 Spring Simulation Interoperability Workshop (SIW). A primary objective of the Smackdown event is to provide college students with hands-on experience in developing distributed simulations using High Level Architecture (HLA). Participating for the second time, the University of Alabama in Huntsville (UAHuntsville) deployed four federates, two federates simulated a communications server and a lunar communications satellite with a radio. The other two federates generated 3D computer graphics displays for the communication satellite constellation and for the surface based lunar resupply mission. Using the Light-Weight Java Graphics Library, the satellite display federate presented a lunar-texture mapped sphere of the moon and four Telemetry Data Relay Satellites (TDRS), which received object attributes from the lunar communications satellite federate to drive their motion. The surface mission display federate was an enhanced version of the federate developed by ForwardSim, Inc. for the 2011 Smackdown simulation. Enhancements included a dead-reckoning algorithm and a visual indication of which communication satellite was in line of sight of Hadley Rille. This paper concentrates on these two federates by describing the functions, algorithms, HLA object attributes received from other federates, development experiences and recommendations for future, participating Smackdown teams.
Three-dimensional radiative transfer on a massively parallel computer
NASA Astrophysics Data System (ADS)
Vath, H. M.
1994-04-01
We perform 3D radiative transfer calculations in non-local thermodynamic equilibrium (NLTE) in the simple two-level atom approximation on the Mas-Par MP-1, which contains 8192 processors and is a single instruction multiple data (SIMD) machine, an example of the new generation of massively parallel computers. On such a machine, all processors execute the same command at a given time, but on different data. To make radiative transfer calculations efficient, we must re-consider the numerical methods and storage of data. To solve the transfer equation, we adopt the short characteristic method and examine different acceleration methods to obtain the source function. We use the ALI method and test local and non-local operators. Furthermore, we compare the Ng and the orthomin methods of acceleration. We also investigate the use of multi-grid methods to get fast solutions for the NLTE case. In order to test these numerical methods, we apply them to two problems with and without periodic boundary conditions.
NASA Technical Reports Server (NTRS)
Davis, Steven B.
1990-01-01
Visual aids are valuable assets to engineers for design, demonstration, and evaluation. Discussed here are a variety of advanced three-dimensional graphic techniques used to enhance the displays of test aircraft dynamics. The new software's capabilities are examined and possible future uses are considered.
NASA Astrophysics Data System (ADS)
Sabbagh, Harold A.; Murphy, R. Kim; Sabbagh, Elias H.
2016-02-01
In past work we have developed a rigorous electromagnetic model and an inversion algorithm for the three-dimensional NDE of advanced composite materials. This approach extends Victor Technologies' work in eddy-current NDE of conventional metals, and allows one to determine in localized regions the fiber-resin ratio in graphite-epoxy, and to determine those anomalies, e.g., delaminations, broken fibers, moisture content, etc., that can be reconstructed by our inversion method. In developing the model, we applied rigorous electromagnetic theory to determine a Green's function for a slab of anisotropic composite material, and then determine the integral relations for the forward and inverse problems using the Green's function. In addition, we have given examples of the solution of forward and inverse problems using these algorithms.
NASA Technical Reports Server (NTRS)
Povinelli, L. A.
1984-01-01
An assessment of several three dimensional inviscid turbine aerodynamic computer codes and loss models used at the NASA Lewis Research Center is presented. Five flow situations are examined, for which both experimental data and computational results are available. The five flows form a basis for the evaluation of the computational procedures. It was concluded that stator flows may be calculated with a high degree of accuracy, whereas, rotor flow fields are less accurately determined. Exploitation of contouring, learning, bowing, and sweeping will require a three dimensional viscous analysis technique.
NASA Technical Reports Server (NTRS)
Wong, K. W.
1974-01-01
Program THREED was developed for the purpose of a research study on the treatment of control data in lunar phototriangulation. THREED is the code name of a computer program for performing absolute orientation by the method of three-dimensional projective transformation. It has the capability of performing complete error analysis on the computed transformation parameters as well as the transformed coordinates.
Computer program for assessing the theoretical performance of a three dimensional inlet
NASA Technical Reports Server (NTRS)
Agnone, A. M.; Kung, F.
1972-01-01
A computer program for determining the theoretical performance of a three dimensional inlet is presented. An analysis for determining the capture area, ram force, spillage force, and surface pressure force is presented, along with the necessary computer program. A sample calculation is also included.
NASA Technical Reports Server (NTRS)
Tanaka, K.; Hirose, H.
1986-01-01
The development of transonic aerodynamic computation methods and specific examples, as well as examples of three-dimensional transonic computation in design, are discussed. The case of the transonic transport and the case of the small transport are analyzed. Requirements for programs of the future are itemized.
NASA Technical Reports Server (NTRS)
Ashbaugh, J. B.; Roland, D. P.; Laird, L. F.
1978-01-01
DSPOBJ is a FORTRAN subroutine to control the display of three-dimensional line networks on a stand-alone, general-purpose, interactive computer graphics system. The program controls the creation and manipulation of transformation matrices for the display and control of multiple sets of line networks. It provides advanced graphics features such as independent and global scaling, rotation and translation, cross-sectioning, reflection, and simultaneous display of four views.
NASA Technical Reports Server (NTRS)
Craidon, C. B.
1975-01-01
A computer program that uses a three-dimensional geometric technique for fitting a smooth surface to the component parts of an aircraft configuration is presented. The resulting surface equations are useful in performing various kinds of calculations in which a three-dimensional mathematical description is necessary. Programs options may be used to compute information for three-view and orthographic projections of the configuration as well as cross-section plots at any orientation through the configuration. The aircraft geometry input section of the program may be easily replaced with a surface point description in a different form so that the program could be of use for any three-dimensional surface equations.
GEO3D - Three-Dimensional Computer Model of a Ground Source Heat Pump System
James Menart
2013-06-07
This file is the setup file for the computer program GEO3D. GEO3D is a computer program written by Jim Menart to simulate vertical wells in conjunction with a heat pump for ground source heat pump (GSHP) systems. This is a very detailed three-dimensional computer model. This program produces detailed heat transfer and temperature field information for a vertical GSHP system.
NASA Astrophysics Data System (ADS)
Kim, Kwang-Ho
Three-dimensional computation of turbulent flow in curved ducts and spiral turbine casings is performed. Mathematical models are described by basic equations resolved by a developed numerical partial parabolic computation procedure. Effect of turbulent oscillations on friction force is analyzed by Prandtl mixing length flow theory. Computational procedure is tested on a 90 deg curved channel. Main flow characteristics, secondary flow, double vortex formation, retroaction, and outlet boundary conditions are considered. Mathematical and experimental results are concordant.
An Exploration of Three-Dimensional Integrated Assessment for Computational Thinking
ERIC Educational Resources Information Center
Zhong, Baichang; Wang, Qiyun; Chen, Jie; Li, Yi
2016-01-01
Computational thinking (CT) is a fundamental skill for students, and assessment is a critical factor in education. However, there is a lack of effective approaches to CT assessment. Therefore, we designed the Three-Dimensional Integrated Assessment (TDIA) framework in this article. The TDIA has two aims: one was to integrate three dimensions…
Angular interpolations and splice options for three-dimensional transport computations
Abu-Shumays, I.K.; Yehnert, C.E.
1996-01-01
New, accurate and mathematically rigorous angular Interpolation strategies are presented. These strategies preserve flow and directionality separately over each octant of the unit sphere, and are based on a combination of spherical harmonics expansions and least squares algorithms. Details of a three-dimensional to three-dimensional (3-D to 3-D) splice method which utilizes the new angular interpolations are summarized. The method has been implemented in a multidimensional discrete ordinates transport computer program. Various features of the splice option are illustrated by several applications to a benchmark Dog-Legged Void Neutron (DLVN) streaming and transport experimental assembly.
Computation of three-dimensional shock wave and boundary-layer interactions
NASA Technical Reports Server (NTRS)
Hung, C. M.
1985-01-01
Computations of the impingement of an oblique shock wave on a cylinder and a supersonic flow past a blunt fin mounted on a plate are used to study three dimensional shock wave and boundary layer interaction. In the impingement case, the problem of imposing a planar impinging shock as an outer boundary condition is discussed and the details of particle traces in windward and leeward symmetry planes and near the body surface are presented. In the blunt fin case, differences between two dimensional and three dimensional separation are discussed, and the existence of an unique high speed, low pressure region under the separated spiral vortex core is demonstrated. The accessibility of three dimensional separation is discussed.
Three-Dimensional Ignition and Flame Propagation Above Liquid Fuel Pools: Computational Analysis
NASA Technical Reports Server (NTRS)
Cai, Jinsheng; Sirignano, William A.
2001-01-01
A three-dimensional unsteady reactive Navier-Stokes code is developed to study the ignition and flame spread above liquid fuels initially below the flashpoint temperature. Opposed air flow to the flame spread due to forced and/or natural convection is considered. Pools of finite width and length are studied in air channels of prescribed height and width. Three-dimensional effects of the flame front near the edge of the pool are captured in the computation. The formation of a recirculation zone in the gas phase similar to that found in two-dimensional calculations is also present in the three-dimensional calculations. Both uniform spread and pulsating spread modes are found in the calculated results.
Computational strategies for three-dimensional flow simulations on distributed computer systems
NASA Technical Reports Server (NTRS)
Sankar, Lakshmi N.; Weed, Richard A.
1995-01-01
This research effort is directed towards an examination of issues involved in porting large computational fluid dynamics codes in use within the industry to a distributed computing environment. This effort addresses strategies for implementing the distributed computing in a device independent fashion and load balancing. A flow solver called TEAM presently in use at Lockheed Aeronautical Systems Company was acquired to start this effort. The following tasks were completed: (1) The TEAM code was ported to a number of distributed computing platforms including a cluster of HP workstations located in the School of Aerospace Engineering at Georgia Tech; a cluster of DEC Alpha Workstations in the Graphics visualization lab located at Georgia Tech; a cluster of SGI workstations located at NASA Ames Research Center; and an IBM SP-2 system located at NASA ARC. (2) A number of communication strategies were implemented. Specifically, the manager-worker strategy and the worker-worker strategy were tested. (3) A variety of load balancing strategies were investigated. Specifically, the static load balancing, task queue balancing and the Crutchfield algorithm were coded and evaluated. (4) The classical explicit Runge-Kutta scheme in the TEAM solver was replaced with an LU implicit scheme. And (5) the implicit TEAM-PVM solver was extensively validated through studies of unsteady transonic flow over an F-5 wing, undergoing combined bending and torsional motion. These investigations are documented in extensive detail in the dissertation, 'Computational Strategies for Three-Dimensional Flow Simulations on Distributed Computing Systems', enclosed as an appendix.
NASA Astrophysics Data System (ADS)
Dandois, J.; Ellis, E. C.
2009-12-01
Urban and other populated and used landscapes today cover a greater extent globally than do wild ecosystems. Methods for accurate ecological measurements on their vegetation and other ecological properties are therefore essential for ecology and earth science. Yet human landscapes are characterized by complex mosaics of vegetation and built structures that are heterogeneous at very fine spatial scales, therefore defying ecological measurements by conventional two dimensional remote sensing techniques, even when these are applied at fine spatial scales. To better measure and understand human-environment interactions within densely populated landscapes, high-spatial resolution three dimensional (3D) remote sensing techniques are needed. Current methods of remote sensing from aerial and satellite platforms are able to resolve land cover and three-dimensional structure using a combination of passive and active sensor technologies (e.g., optical imagers and LIDAR sensors). Despite such advances, there remain substantial gaps in knowledge about the distribution and biological characteristics of vegetation across all regions of earth, especially in densely populated environments. Here we present new methods for very fine scale 3D remote sensing of vegetation structure using computer vision techniques applied to standard digital photographs taken from consumer grade digital cameras mounted on low-altitude aerial platforms. Computer vision algorithms are used to produce 3D geometry from overlapping images, generating datasets very similar to LIDAR point clouds, and useful for measuring vegetation structure characteristics like canopy structure and tree height. These are then used to estimate vegetation biophysical characteristics like canopy density and biomass. Preliminary results demonstrate that this approach offers great promise as a tool for obtaining ecological measurements such as canopy height and vegetation form at the scale of individual trees in a low-cost and
High-resolution three-dimensional imaging by synchrotron-radiation computed laminography
NASA Astrophysics Data System (ADS)
Helfen, L.; Baumbach, T.; Pernot, P.; Mikulík, P.; DiMichiel, M.; Baruchel, J.
2006-08-01
The methodical development and first instrumental implementation of computed laminography / tomosynthesis using synchrotron radiation are presented. The technique was developed for three-dimensional imaging of flat and laterally extended objects with high spatial resolution. This paper introduces the fundamental principle of the imaging process and discusses the method's particularities in comparison to computed tomography and computed laminography / digital tomosynthesis. Introducing a simple scanning geometry adapted to the particular experimental conditions of synchrotron imaging set-ups (such as the stationary source and a parallel beam) allows us to combine the advantages of laminography and those provided by synchrotron radiation, for instance monochromatic radiation in order to avoid beam hardening artefacts, high beam intensity for achieving high spatial resolution and fast scanning times or spatial coherence for exploiting phase contrast. The potential of the method for three-dimensional imaging of microelectronic devices is demonstrated by examples of flip-chip bonded and wire-bonded devices.
NASA Technical Reports Server (NTRS)
Chen, Y. S.
1986-01-01
In this report, a numerical method for solving the equations of motion of three-dimensional incompressible flows in nonorthogonal body-fitted coordinate (BFC) systems has been developed. The equations of motion are transformed to a generalized curvilinear coordinate system from which the transformed equations are discretized using finite difference approximations in the transformed domain. The hybrid scheme is used to approximate the convection terms in the governing equations. Solutions of the finite difference equations are obtained iteratively by using a pressure-velocity correction algorithm (SIMPLE-C). Numerical examples of two- and three-dimensional, laminar and turbulent flow problems are employed to evaluate the accuracy and efficiency of the present computer code. The user's guide and computer program listing of the present code are also included.
NASA Technical Reports Server (NTRS)
Subramanian, S. V.; Bozzola, R.; Povinelli, L. A.
1986-01-01
The performance of a three dimensional computer code developed for predicting the flowfield in stationary and rotating turbomachinery blade rows is described in this study. The four stage Runge-Kutta numerical integration scheme is used for solving the governing flow equations and yields solution to the full, three dimensional, unsteady Euler equations in cylindrical coordinates. This method is fully explicit and uses the finite volume, time marching procedure. In order to demonstrate the accuracy and efficiency of the code, steady solutions were obtained for several cascade geometries under widely varying flow conditions. Computed flowfield results are presented for a fully subsonic turbine stator and a low aspect ratio, transonic compressor rotor blade under maximum flow and peak efficiency design conditions. Comparisons with Laser Anemometer measurements and other numerical predictions are also provided to illustrate that the present method predicts important flow features with good accuracy and can be used for cost effective aerodynamic design studies.
NASA Technical Reports Server (NTRS)
Decker, Arthur J.; Izen, Steven H.
1991-01-01
A theory to determine the properties of a fluid from measurements of its projections was developed and tested. Viewing cones as small as 10 degrees were evaluated, with the only assumption being that the property was space limited. The results of applying the theory to numerical and actual interferograms of a spherical discontinuity of refractive index are presented. The theory was developed to test the practicality and limits of using three-dimensional computer tomography in internal fluid dynamics.
NASA Technical Reports Server (NTRS)
Decker, Arthur J.; Izen, Steven H.
1992-01-01
A theory to determine the properties of a fluid from measurements of its projections was developed and tested. Viewing cones as small as 10 degrees were evaluated, with the only assumption being that the property was space limited. The results of applying the theory to numerical and actual interferograms of a spherical discontinuity of refractive index are presented. The theory was developed to test the practicality and limits of using three dimensional computer tomography in internal fluid dynamics.
A computer program for fitting smooth surfaces to three-dimensional aircraft configurations
NASA Technical Reports Server (NTRS)
Craidon, C. B.; Smith, R. E., Jr.
1975-01-01
A computer program developed to fit smooth surfaces to the component parts of three-dimensional aircraft configurations was described. The resulting equation definition of an aircraft numerical model is useful in obtaining continuous two-dimensional cross section plots in arbitrarily defined planes, local tangents, enriched surface plots and other pertinent geometric information; the geometry organization used as input to the program has become known as the Harris Wave Drag Geometry.
Three-Dimensional Computational Model for Flow in an Over-Expanded Nozzle With Porous Surfaces
NASA Technical Reports Server (NTRS)
Abdol-Hamid, K. S.; Elmiligui, Alaa; Hunter, Craig A.; Massey, Steven J.
2006-01-01
A three-Dimensional computational model is used to simulate flow in a non-axisymmetric, convergent-divergent nozzle incorporating porous cavities for shock-boundary layer interaction control. The nozzle has an expansion ratio (exit area/throat area) of 1.797 and a design nozzle pressure ratio of 8.78. Flow fields for the baseline nozzle (no porosity) and for the nozzle with porous surfaces of 10% openness are computed for Nozzle Pressure Ratio (NPR) varying from 1.29 to 9.54. The three dimensional computational results indicate that baseline (no porosity) nozzle performance is dominated by unstable, shock-induced, boundary-layer separation at over-expanded conditions. For NPR less than or equal to 1.8, the separation is three dimensional, somewhat unsteady, and confined to a bubble (with partial reattachment over the nozzle flap). For NPR greater than or equal to 2.0, separation is steady and fully detached, and becomes more two dimensional as NPR increased. Numerical simulation of porous configurations indicates that a porous patch is capable of controlling off design separation in the nozzle by either alleviating separation or by encouraging stable separation of the exhaust flow. In the present paper, computational simulation results, wall centerline pressure, mach contours, and thrust efficiency ratio are presented, discussed and compared with experimental data. Results indicate that comparisons are in good agreement with experimental data. The three-dimensional simulation improves the comparisons for over-expanded flow conditions as compared with two-dimensional assumptions.
Three-dimensional computations of transverse hydrogen jet combustion in a supersonic airstream
NASA Technical Reports Server (NTRS)
Uenishi, K.; Rogers, R. C.; Northam, G. B.
1987-01-01
A computational fluid dynamics (CFD) code is being developed to compute the mixing and combustion of hydrogen fuel in the turbulent flow fields of supersonic combustion ramjets (scramjet). The code solves the three-dimensional Reynolds time-averaged complete Navier-Stokes equations including transport equations for a four species, two reaction, global finite rate chemistry model. The code was applied to the case of transverse injection of hydrogen from a sonic circular orifice into a supersonic airstream. The equations were numerically integrated using MacCormack's explicit method, and the algebraic eddy viscosity model of Baldwin-Lomax was used to model the turbulence. In the species transport and energy equations, diffusion coefficients based on Fick's Law and an assumption of unit Lewis number were applied. Computed features of the three-dimensional flow field are depicted by static pressure, static temperature, mass fraction of species, and velocity vectors. For engineering interest, mixing and combustion parameters were examined to assess the effect of injector diameter, injected fuel pressure, fuel-air ratio, and spacing of fuel injectors. The objective of the present paper is to demonstrate the capability of the present three-dimensional spatially elliptic, CFD code for turbulent, reacting flow. Application of the code to specific supersonic combustion configurations is planned.
A combined direct/inverse three-dimensional transonic wing design method for vector computers
NASA Technical Reports Server (NTRS)
Weed, R. A.; Carlson, L. A.; Anderson, W. K.
1984-01-01
A three-dimensional transonic-wing design algorithm for vector computers is developed, and the results of sample computations are presented graphically. The method incorporates the direct/inverse scheme of Carlson (1975), a Cartesian grid system with boundary conditions applied at a mean plane, and a potential-flow solver based on the conservative form of the full potential equation and using the ZEBRA II vectorizable solution algorithm of South et al. (1980). The accuracy and consistency of the method with regard to direct and inverse analysis and trailing-edge closure are verified in the test computations.
NASA Technical Reports Server (NTRS)
Perucchio, R.; Ingraffea, A. R.
1984-01-01
The establishment of the boundary element method (BEM) as a valid tool for solving problems in structural mechanics and in other fields of applied physics is discussed. The development of an integrated interactive computer graphic system for the application of the BEM to three dimensional problems in elastostatics is described. The integration of interactive computer graphic techniques and the BEM takes place at the preprocessing and postprocessing stages of the analysis process, when, respectively, the data base is generated and the results are interpreted. The interactive computer graphic modeling techniques used for generating and discretizing the boundary surfaces of a solid domain are outlined.
Three-dimensional compressible turbulent computations for a nondiffusing S-duct
NASA Technical Reports Server (NTRS)
Harloff, G. J.; Debonis, J. R.; Smith, C. F.; Bruns, J. E.
1992-01-01
The PARC3D code was used to compute the compressible turbulent flow within a three dimensional, nondiffusing S-duct. A frame of reference is provided for future computational fluid dynamics studies of internal flows with strong secondary flows and provides an understanding of the performance characteristics of a typical S-duct with attached flow. The predicted results, obtained with both H- and O-grids, are compared with the experimental wall pressure, static and total pressure fields, and velocity vectors. Additionally, computed boundary layer thickness, velocity profiles in wall coordinates, and skin friction values are presented.
Schlusselberg, D.S.; Simon, T.R.; Smith, W.K.; Woodward, D.J.; Parkey, R.W.
1985-05-01
Emission computed tomography (ECT) quantitatively localizes radionuclide tracer distributions within a three-dimensional (3D) volume. Currently available techniques limit the display of this information to series of cross-sectional or rotating images. Such techniques of ten rely on special viewing equipment to synthesize the image series into a volumetric display. The authors have developed new algorithms that generate 3D images of radiotracer distributions using computerized analysis of tomographic data. Imaging strategies including transparent volumes, surface models, color-coded circumferential histograms and transparent slices are combined to produce a single image that contains the quantitative distributional information. While the images can be displayed on most raster-based display devices, they are suitable for archiving and distribution as single image photographs. This choice of formats enhances the value of the technique for communicating scintigraphic information to referring physicians while maintaining the quantitative integrity of the data. The technique has been successfully applied to a variety of ECT examination including brain, heart, liver and bone studies.
High performance computing for three-dimensional agent-based molecular models.
Pérez-Rodríguez, G; Pérez-Pérez, M; Fdez-Riverola, F; Lourenço, A
2016-07-01
Agent-based simulations are increasingly popular in exploring and understanding cellular systems, but the natural complexity of these systems and the desire to grasp different modelling levels demand cost-effective simulation strategies and tools. In this context, the present paper introduces novel sequential and distributed approaches for the three-dimensional agent-based simulation of individual molecules in cellular events. These approaches are able to describe the dimensions and position of the molecules with high accuracy and thus, study the critical effect of spatial distribution on cellular events. Moreover, two of the approaches allow multi-thread high performance simulations, distributing the three-dimensional model in a platform independent and computationally efficient way. Evaluation addressed the reproduction of molecular scenarios and different scalability aspects of agent creation and agent interaction. The three approaches simulate common biophysical and biochemical laws faithfully. The distributed approaches show improved performance when dealing with large agent populations while the sequential approach is better suited for small to medium size agent populations. Overall, the main new contribution of the approaches is the ability to simulate three-dimensional agent-based models at the molecular level with reduced implementation effort and moderate-level computational capacity. Since these approaches have a generic design, they have the major potential of being used in any event-driven agent-based tool. PMID:27372059
Computational analysis of three-dimensional epithelial morphogenesis using vertex models
Du, XinXin; Osterfield, Miriam; Shvartsman, Stanislav Y.
2014-01-01
The folding of epithelial sheets, accompanied by cell shape changes and rearrangements, gives rise to three-dimensional structures during development. Recently, some aspects of epithelial morphogenesis have been modeled using vertex models, in which each cell is approximated by a polygon; however, these models have been largely confined to two dimensions. Here, we describe an adaptation of these models in which the classical two-dimensional vertex model is embedded in three dimensions. This modification allows for the construction of complex three-dimensional shapes from simple sheets of cells. We describe algorithmic, computational, and biophysical aspects of our model, with the view that it may be useful for formulating and testing hypotheses regarding the mechanical forces underlying a wide range of morphogenetic processes. PMID:25410646
Evaluation of the three-dimensional parabolic flow computer program SHIP
NASA Technical Reports Server (NTRS)
Pan, Y. S.
1978-01-01
The three-dimensional parabolic flow program SHIP designed for predicting supersonic combustor flow fields is evaluated to determine its capabilities. The mathematical foundation and numerical procedure are reviewed; simplifications are pointed out and commented upon. The program is then evaluated numerically by applying it to several subsonic and supersonic, turbulent, reacting and nonreacting flow problems. Computational results are compared with available experimental or other analytical data. Good agreements are obtained when the simplifications on which the program is based are justified. Limitations of the program and the needs for improvement and extension are pointed out. The present three dimensional parabolic flow program appears to be potentially useful for the development of supersonic combustors.
Numerical computation of three-dimensional blunt body flow fields with an impinging shock
NASA Technical Reports Server (NTRS)
Holst, T. L.; Tannehill, J. C.
1975-01-01
A time-marching finite-difference method was used to solve the compressible Navier-Stokes equations for the three-dimensional wing-leading-edge shock impingement problem. The bow shock was treated as a discontinuity across which the exact shock jump conditions were applied. All interior shock layer detail such as shear layers, shock waves, jets, and the wall boundary layer were automatically captured in the solution. The impinging shock was introduced by discontinuously changing the freestream conditions across the intersection line at the bow shock. A special storage-saving procedure for sweeping through the finite-difference mesh was developed which reduces the required amount of computer storage by at least a factor of two without sacrificing the execution time. Numerical results are presented for infinite cylinder blunt body cases as well as the three-dimensional shock impingement case. The numerical results are compared with existing experimental and theoretical results.
NASA Technical Reports Server (NTRS)
Dulikravich, D. S.
1980-01-01
A computer program is presented which numerically solves an exact, full potential equation (FPE) for three dimensional, steady, inviscid flow through an isolated wind turbine rotor. The program automatically generates a three dimensional, boundary conforming grid and iteratively solves the FPE while fully accounting for both the rotating cascade and Coriolis effects. The numerical techniques incorporated involve rotated, type dependent finite differencing, a finite volume method, artificial viscosity in conservative form, and a successive line overrelaxation combined with the sequential grid refinement procedure to accelerate the iterative convergence rate. Consequently, the WIND program is capable of accurately analyzing incompressible and compressible flows, including those that are locally transonic and terminated by weak shocks. The program can also be used to analyze the flow around isolated aircraft propellers and helicopter rotors in hover as long as the total relative Mach number of the oncoming flow is subsonic.
A Computer Program for the Calculation of Three-Dimensional Transonic Nacelle/Inlet Flowfields
NASA Technical Reports Server (NTRS)
Vadyak, J.; Atta, E. H.
1983-01-01
A highly efficient computer analysis was developed for predicting transonic nacelle/inlet flowfields. This algorithm can compute the three dimensional transonic flowfield about axisymmetric (or asymmetric) nacelle/inlet configurations at zero or nonzero incidence. The flowfield is determined by solving the full-potential equation in conservative form on a body-fitted curvilinear computational mesh. The difference equations are solved using the AF2 approximate factorization scheme. This report presents a discussion of the computational methods used to both generate the body-fitted curvilinear mesh and to obtain the inviscid flow solution. Computed results and correlations with existing methods and experiment are presented. Also presented are discussions on the organization of the grid generation (NGRIDA) computer program and the flow solution (NACELLE) computer program, descriptions of the respective subroutines, definitions of the required input parameters for both algorithms, a brief discussion on interpretation of the output, and sample cases to illustrate application of the analysis.
Three-dimensional unsteady flow calculations in an advanced gas generator turbine
NASA Technical Reports Server (NTRS)
Rangwalla, Akil A.
1993-01-01
This paper deals with the application of a three-dimensional, unsteady Navier-Stokes code for predicting the unsteady flow in a single stage of an advanced gas generator turbine. The numerical method solves the three-dimensional thin-layer Navier-Stokes equations, using a system of overlaid grids, which allow for relative motion between the rotor and stator airfoils. Results in the form of time averaged pressures and pressure amplitudes on the airfoil surfaces will be shown. In addition, instantaneous contours of pressure, Mach number, etc. will be presented in order to provide a greater understanding of the inviscid as well as the viscous aspects of the flowfield. Also, relevant secondary flow features such as cross-plane velocity vectors and total pressure contours will be presented. Prior work in two-dimensions has indicated that for the advanced designs, the unsteady interactions can play a significant role in turbine performance. These interactions affect not only the stage efficiency but can substantially alter the time-averaged features of the flow. This work is a natural extension of the work done in two-dimensions and hopes to address some of the issues raised by the two-dimensional calculations. These calculations are being performed as an integral part of an actual design process and demonstrate the value of unsteady rotor-stator interaction calculations in the design of turbomachines.
Papantoniou, Ioannis; Sonnaert, Maarten; Geris, Liesbet; Luyten, Frank P; Schrooten, Jan; Kerckhofs, Greet
2014-03-01
To successfully implement tissue-engineered (TE) constructs as part of a clinical therapy, it is necessary to develop quality control tools that will ensure accurate and consistent TE construct release specifications. Hence, advanced methods to monitor TE construct properties need to be further developed. In this study, we showed proof of concept for contrast-enhanced nanofocus computed tomography (CE-nano-CT) as a whole-construct imaging technique with a noninvasive potential that enables three-dimensional (3D) visualization and quantification of in vitro engineered extracellular matrix (ECM) in TE constructs. In particular, we performed a 3D qualitative and quantitative structural and spatial assessment of the in vitro engineered ECM, formed during static and perfusion bioreactor cell culture in 3D TE scaffolds, using two contrast agents, namely, Hexabrix® and phosphotungstic acid (PTA). To evaluate the potential of CE-nano-CT, a comparison was made to standardly used techniques such as Live/Dead viability/cytotoxicity, Picrosirius Red staining, and to net dry weight measurements of the TE constructs. When using Hexabrix as the contrast agent, the ECM volume fitted linearly with the net dry ECM weight independent from the flow rate used, thus suggesting that it stains most of the ECM. When using PTA as the contrast agent, comparing to net weight measurements showed that PTA only stains a part of the ECM. This was attributed to the binding specificity of this contrast agent. In addition, the PTA-stained CE-nano-CT data showed pronounced distinction between flow conditions when compared to Hexabrix, indicating culture-specific structural ECM differences. This novel type of information can contribute to optimize bioreactor culture conditions and potentially critical quality characteristics of TE constructs such as ECM quantity and homogeneity, facilitating the gradual transformation of TE constructs in well-characterized TE products. PMID:23800097
Papantoniou, Ioannis; Sonnaert, Maarten; Geris, Liesbet; Luyten, Frank P.; Kerckhofs, Greet
2014-01-01
To successfully implement tissue-engineered (TE) constructs as part of a clinical therapy, it is necessary to develop quality control tools that will ensure accurate and consistent TE construct release specifications. Hence, advanced methods to monitor TE construct properties need to be further developed. In this study, we showed proof of concept for contrast-enhanced nanofocus computed tomography (CE-nano-CT) as a whole-construct imaging technique with a noninvasive potential that enables three-dimensional (3D) visualization and quantification of in vitro engineered extracellular matrix (ECM) in TE constructs. In particular, we performed a 3D qualitative and quantitative structural and spatial assessment of the in vitro engineered ECM, formed during static and perfusion bioreactor cell culture in 3D TE scaffolds, using two contrast agents, namely, Hexabrix® and phosphotungstic acid (PTA). To evaluate the potential of CE-nano-CT, a comparison was made to standardly used techniques such as Live/Dead viability/cytotoxicity, Picrosirius Red staining, and to net dry weight measurements of the TE constructs. When using Hexabrix as the contrast agent, the ECM volume fitted linearly with the net dry ECM weight independent from the flow rate used, thus suggesting that it stains most of the ECM. When using PTA as the contrast agent, comparing to net weight measurements showed that PTA only stains a part of the ECM. This was attributed to the binding specificity of this contrast agent. In addition, the PTA-stained CE-nano-CT data showed pronounced distinction between flow conditions when compared to Hexabrix, indicating culture-specific structural ECM differences. This novel type of information can contribute to optimize bioreactor culture conditions and potentially critical quality characteristics of TE constructs such as ECM quantity and homogeneity, facilitating the gradual transformation of TE constructs in well-characterized TE products. PMID:23800097
Three-dimensional multigrid Navier-Stokes computations for turbomachinery applications
NASA Technical Reports Server (NTRS)
Subramanian, S. V.
1989-01-01
The fully three-dimensional, time-dependent compressible Navier-Stokes equations in cylindrical coordinates are presently used, in conjunction with the multistage Runge-Kutta numerical integration scheme for solution of the governing flow equations, to simulate complex flowfields within turbomechanical components whose pertinent effects encompass those of viscosity, compressibility, blade rotation, and tip clearance. Computed results are presented for selected cascades, emphasizing the code's capabilities in the accurate prediction of such features as airfoil loadings, exit flow angles, shocks, and secondary flows. Computations for several test cases have been performed on a Cray-YMP, using nearly 90,000 grid points.
Three-dimensional multigrid Navier-Stokes computations for turbomachinery applications
NASA Astrophysics Data System (ADS)
Subramanian, S. V.
1989-07-01
The fully three-dimensional, time-dependent compressible Navier-Stokes equations in cylindrical coordinates are presently used, in conjunction with the multistage Runge-Kutta numerical integration scheme for solution of the governing flow equations, to simulate complex flowfields within turbomechanical components whose pertinent effects encompass those of viscosity, compressibility, blade rotation, and tip clearance. Computed results are presented for selected cascades, emphasizing the code's capabilities in the accurate prediction of such features as airfoil loadings, exit flow angles, shocks, and secondary flows. Computations for several test cases have been performed on a Cray-YMP, using nearly 90,000 grid points.
Three-dimensional multigrid Navier-Stokes computations for turbomachinery applications
Subramanian, S. V.
1989-01-01
The fully three-dimensional, time-dependent compressible Navier-Stokes equations in cylindrical coordinates are presently used, in conjunction with the multistage Runge-Kutta numerical integration scheme for solution of the governing flow equations, to simulate complex flowfields within turbomechanical components whose pertinent effects encompass those of viscosity, compressibility, blade rotation, and tip clearance. Computed results are presented for selected cascades, emphasizing the code's capabilities in the accurate prediction of such features as airfoil loadings, exit flow angles, shocks, and secondary flows. Computations for several test cases have been performed on a Cray-YMP, using nearly 90,000 grid points. 18 refs.
Simulations of Failure via Three-Dimensional Cracking in Fuel Cladding for Advanced Nuclear Fuels
Lu, Hongbing; Bukkapatnam, Satish; Harimkar, Sandip; Singh, Raman; Bardenhagen, Scott
2014-01-09
Enhancing performance of fuel cladding and duct alloys is a key means of increasing fuel burnup. This project will address the failure of fuel cladding via three-dimensional cracking models. Researchers will develop a simulation code for the failure of the fuel cladding and validate the code through experiments. The objective is to develop an algorithm to determine the failure of fuel cladding in the form of three-dimensional cracking due to prolonged exposure under varying conditions of pressure, temperature, chemical environment, and irradiation. This project encompasses the following tasks: 1. Simulate 3D crack initiation and growth under instantaneous and/or fatigue loads using a new variant of the material point method (MPM); 2. Simulate debonding of the materials in the crack path using cohesive elements, considering normal and shear traction separation laws; 3. Determine the crack propagation path, considering damage of the materials incorporated in the cohesive elements to allow the energy release rate to be minimized; 4. Simulate the three-dimensional fatigue crack growth as a function of loading histories; 5. Verify the simulation code by comparing results to theoretical and numerical studies available in the literature; 6. Conduct experiments to observe the crack path and surface profile in unused fuel cladding and validate against simulation results; and 7. Expand the adaptive mesh refinement infrastructure parallel processing environment to allow adaptive mesh refinement at the 3D crack fronts and adaptive mesh merging in the wake of cracks. Fuel cladding is made of materials such as stainless steels and ferritic steels with added alloying elements, which increase stability and durability under irradiation. As fuel cladding is subjected to water, chemicals, fission gas, pressure, high temperatures, and irradiation while in service, understanding performance is essential. In the fast fuel used in advanced burner reactors, simulations of the nuclear
Devireddy, Sathya Kumar; Kumar, R. V. Kishore; Gali, Rajasekhar; Kanubaddy, Sridhar Reddy; Rao, Dasari Mallikarjuna; Siddhartha, Mannava
2014-01-01
Objective: The aim was to assess the accuracy of three-dimensional anatomical reductions achieved by open method of treatment in cases of displaced unilateral mandibular subcondylar fractures using preoperative (pre op) and postoperative (post op) computed tomography (CT) scans. Materials and Methods: In this prospective study, 10 patients with unilateral sub condylar fractures confirmed by an orthopantomogram were included. A pre op and post op CT after 1 week of surgical procedure was taken in axial, coronal and sagittal plane along with three-dimensional reconstruction. Standard anatomical parameters, which undergo changes due to fractures of the mandibular condyle were measured in pre and post op CT scans in three planes and statistically analysed for the accuracy of the reduction comparing the following variables: (a) Pre op fractured and nonfractured side (b) post op fractured and nonfractured side (c) pre op fractured and post op fractured side. P < 0.05 was considered as significant. Results: Three-dimensional anatomical reduction was possible in 9 out of 10 cases (90%). The statistical analysis of each parameter in three variables revealed (P < 0.05) that there was a gross change in the dimensions of the parameters obtained in pre op fractured and nonfractured side. When these parameters were assessed in post op CT for the three variables there was no statistical difference between the post op fractured side and non fractured side. The same parameters were analysed for the three variables in pre op fractured and post op fractured side and found significant statistical difference suggesting a considerable change in the dimensions of the fractured side post operatively. Conclusion: The statistical and clinical results in our study emphasised that it is possible to fix the condyle in three-dimensional anatomical positions with open method of treatment and avoid post op degenerative joint changes. CT is the ideal imaging tool and should be used on a regular
Mach 10 computational study of a three-dimensional scramjet inlet flow field
NASA Technical Reports Server (NTRS)
Holland, Scott D.
1995-01-01
The present work documents the computational results for a combined computational and experimental parametric study of the internal aerodynamics of a generic three-dimensional sidewall-compression scramjet inlet configuration at Mach 10. The three-dimensional Navier-Stokes code SCRAMIN was chosen for the computational portion of the study because it uses a well-known and well-proven numerical scheme and has shown favorable comparison with experiment at Mach numbers between 2 and 6. One advantage of CFD was that it provided flow field data for a detailed examination of the internal flow characteristics in addition to the surface properties. The experimental test matrix at Mach 10 included three geometric contraction ratios (3, 5, and 9), three Reynolds numbers (0.55 x 10(exp 6) per foot, 1.14 x 10(exp 6) per foot, and 2.15 x 10(exp 6) per foot), and three cowl positions (at the throat and two forward positions). Computational data for two of these configurations (the contraction ratio of 3, Re = 2.15 x 10(exp 6) per foot, at two cowl positions) are presented along with a detailed analysis of the flow interactions in successive computational planes.
Mach 10 computational study of a three-dimensional scramjet inlet flow field
NASA Technical Reports Server (NTRS)
Holland, Scott D.
1995-01-01
The present work documents the computational results for a combined computational and experimental parametric study of the internal aerodynamics of a generic three-dimensional sidewall-compression scramjet inlet configuration at Mach 10. The three-dimensional Navier-Stokes code SCRAMIN was chosen for the computational portion of the study because it uses a well-known and well-proven numerical scheme and has shown favorable comparison with experiment at Mach numbers between 2 and 6. One advantage of CFD was that it provided flow field data for a detailed examination of the internal flow characteristics in addition to the surface properties. The experimental test matrix at mach 10 included three geometric contraction ratios (3, 5, and 9), three Reynolds numbers (0.55 x 10(exp 6) per foot, 1.14 x 10(exp 6) per foot, and 2.15 x 10(exp 6) per foot), and three cowl positions (at the throat and two forward positions). Computational data for two of these configurations (the contraction ratio of 3, Re = 2.15 x 10 (exp 6) per foot, at two cowl positions) are presented along with a detailed analysis of the flow interactions in successive computational planes.
Three-Dimensional Integration Technology for Advanced Focal Planes and Integrated Circuits
Keast, Craig
2007-02-28
Over the last five years MIT Lincoln Laboratory (MIT-LL) has developed a three-dimensional (3D) circuit integration technology that exploits the advantages of silicon-on-insulator (SOI) technology to enable wafer-level stacking and micrometer-scale electrical interconnection of fully fabricated circuit wafers. Advanced focal plane arrays have been the first applications to exploit the benefits of this 3D integration technology because the massively parallel information flow present in 2D imaging arrays maps very nicely into a 3D computational structure as information flows from circuit-tier to circuit-tier in the z-direction. To date, the MIT-LL 3D integration technology has been used to fabricate four different focal planes including: a 2-tier 64 x 64 imager with fully parallel per-pixel A/D conversion; a 3-tier 640 x 480 imager consisting of an imaging tier, an A/D conversion tier, and a digital signal processing tier; a 2-tier 1024 x 1024 pixel, 4-side-abutable imaging modules for tiling large mosaic focal planes, and a 3-tier Geiger-mode avalanche photodiode (APD) 3-D LIDAR array, using a 30 volt APD tier, a 3.3 volt CMOS tier, and a 1.5 volt CMOS tier. Recently, the 3D integration technology has been made available to the circuit design research community through DARPA-sponsored Multiproject fabrication runs. The first Multiproject Run (3DL1) completed fabrication in early 2006 and included over 30 different circuit designs from 21 different research groups. 3D circuit concepts explored in this run included stacked memories, field programmable gate arrays (FPGAs), and mixed-signal circuits. The second Multiproject Run (3DM2) is currently in fabrication and includes particle detector readouts designed by Fermilab. This talk will provide a brief overview of MIT-LL's 3D-integration process, discuss some of the focal plane applications where the technology is being applied, and provide a summary of some of the Multiproject Run circuit results.
Lighting effects rendering in three-dimensional computer-generated holographic display
NASA Astrophysics Data System (ADS)
Zhang, Hao; Cao, Liangcai; Jin, Guofan
2016-07-01
We present a technique for generating three-dimensional (3-D) computer-generated holograms (CGHs) with realistic lighting effects based on a phase-only spatial light modulator (SLM). Phong reflection model is employed in the calculation of reflectance distribution for CGH synthesizing. Directional point-based algorithm produces realistic lighting effects of the 3-D scenes in processing the ambient, diffuse and specular reflections. A phase-only SLM is used to perform the optical experiments, and the results show that the proposed technique can perform quality reconstructions of the 3-D scenes with high optical efficiency and efficient utilization of the system space-bandwidth product.
NASA Astrophysics Data System (ADS)
Vedenov, A. A.
1994-09-01
Today scientists can create, with the aid of a personal computer three-dimensional (3D) representations of objects—a specific data base, containing not only the space coordinates and colours of all points of an object, but also allowing it be examined from a bird's-eye point of view. The data base reveals the characteristic features of the object as a whole and allows them to be named. Examples of 3D representations are given and the principles of their creation and viewing are discussed.
An improved method for computer generation of three-dimensional digital holography
NASA Astrophysics Data System (ADS)
Hu, Yanlei; Ma, Jianqiang; Chen, Yuhang; Li, Jiawen; Huang, Wenhao; Chu, Jiaru
2013-12-01
A novel method is proposed for designing optimized three-dimensional computer-generated holograms (CGHs). A series of spherical wave factors are introduced into the conventional optimal rotation angle (ORA) algorithm to achieve a varying amount of defocus along the optical axis, and the distraction terms are minimized during the iterative process. Both numerical simulation and experimental reconstructions are presented to demonstrate that this method is able to yield excellent multilayer patterns with high uniformity and signal-to-noise ratio (SNR). This method is significant for applications in laser 3D printing and multilayer data recording.
NASA Astrophysics Data System (ADS)
Yeom, Seokwon; Lee, Dongsu; Son, Jung-Young; Kim, Shin-Hwan
2009-09-01
In this paper, we discuss computational reconstruction and statistical pattern classification using integral imaging. Three-dimensional object information is numerically reconstructed at arbitrary depth-levels by averaging the corresponding pixels. The longitudinal distance and object boundary are estimated where the standard deviation of the intensity is minimized. Fisher linear discriminant analysis combined with principal component analysis is adopted for the classification of out-of-plane rotated objects. The Fisher linear discriminant analysis maximizes the class-discrimination while the principal component analysis minimizes the error between the original and the restored images. The presented method provides promising results for the distortion-tolerant pattern classification.
Three-dimensional computational study of asymmetric flows using Navier-Stokes equations
NASA Technical Reports Server (NTRS)
Cheung, Y. K. (Editor); Lee, J. H. W. (Editor); Leung, A. Y. T. (Editor); Wong, Tin-Chee; Kandil, Osama A.; Liu, C. H.
1992-01-01
The unsteady, compressible, thin-layer Navier-Stokes equations are used to obtain three-dimensional, asymmetric, vortex-flow solutions around cones and cone-cylinder configurations. The equations are solved using an implicit, upwind, flux-difference splitting, finite-volume scheme. The computational applications cover asymmetric flows around a 5 semi-apex angle cone of unit length at various Reynolds number. Next, a cylindrical afterbody of various length is added to the conical forebody to study the effect of the length of cylindrical afterbody on the flow asymmetry. All the asymmetric flow solutions are obtained by using a short-duration side-slip disturbance.
Use of CYBER 203 and CYBER 205 computers for three-dimensional transonic flow calculations
NASA Astrophysics Data System (ADS)
Melson, N. D.; Keller, J. D.
1983-04-01
Experiences are discussed for modifying two three-dimensional transonic flow computer programs (FLO 22 and FLO 27) for use on the CDC CYBER 203 computer system. Both programs were originally written for use on serial machines. Several methods were attempted to optimize the execution of the two programs on the vector machine: leaving the program in a scalar form (i.e., serial computation) with compiler software used to optimize and vectorize the program, vectorizing parts of the existing algorithm in the program, and incorporating a vectorizable algorithm (ZEBRA I or ZEBRA II) in the program. Comparison runs of the programs were made on CDC CYBER 175. CYBER 203, and two pipe CDC CYBER 205 computer systems.
Use of CYBER 203 and CYBER 205 computers for three-dimensional transonic flow calculations
NASA Technical Reports Server (NTRS)
Melson, N. D.; Keller, J. D.
1983-01-01
Experiences are discussed for modifying two three-dimensional transonic flow computer programs (FLO 22 and FLO 27) for use on the CDC CYBER 203 computer system. Both programs were originally written for use on serial machines. Several methods were attempted to optimize the execution of the two programs on the vector machine: leaving the program in a scalar form (i.e., serial computation) with compiler software used to optimize and vectorize the program, vectorizing parts of the existing algorithm in the program, and incorporating a vectorizable algorithm (ZEBRA I or ZEBRA II) in the program. Comparison runs of the programs were made on CDC CYBER 175. CYBER 203, and two pipe CDC CYBER 205 computer systems.
An eddy-current model for three-dimensional nondestructive evaluation of advanced composites
NASA Astrophysics Data System (ADS)
Sabbagh, Harold A.; Murphy, R. Kim; Sabbagh, Elias H.
2015-03-01
We have developed a rigorous electromagnetic model and an inversion algorithm for the three-dimensional NDE of advanced composite materials. This approach extends Victor Technologies' work in eddy-current NDE of conventional metals, and allows one to determine in localized regions the fiber-resin ratio in graphite-epoxy, and to determine those anomalies, e.g., delaminations, broken fibers, moisture content, etc., that can be reconstructed by our inversion method. In developing the model, we apply rigorous electromagnetic theory to determine a Green's function for a slab of anisotropic composite material, and then determine the integral relations for the forward and inverse problems using the Green's function. We will give examples of the solution of forward problems using this model.
Advanced numerical methods for three dimensional two-phase flow calculations
Toumi, I.; Caruge, D.
1997-07-01
This paper is devoted to new numerical methods developed for both one and three dimensional two-phase flow calculations. These methods are finite volume numerical methods and are based on the use of Approximate Riemann Solvers concepts to define convective fluxes versus mean cell quantities. The first part of the paper presents the numerical method for a one dimensional hyperbolic two-fluid model including differential terms as added mass and interface pressure. This numerical solution scheme makes use of the Riemann problem solution to define backward and forward differencing to approximate spatial derivatives. The construction of this approximate Riemann solver uses an extension of Roe`s method that has been successfully used to solve gas dynamic equations. As far as the two-fluid model is hyperbolic, this numerical method seems very efficient for the numerical solution of two-phase flow problems. The scheme was applied both to shock tube problems and to standard tests for two-fluid computer codes. The second part describes the numerical method in the three dimensional case. The authors discuss also some improvements performed to obtain a fully implicit solution method that provides fast running steady state calculations. Such a scheme is not implemented in a thermal-hydraulic computer code devoted to 3-D steady-state and transient computations. Some results obtained for Pressurised Water Reactors concerning upper plenum calculations and a steady state flow in the core with rod bow effect evaluation are presented. In practice these new numerical methods have proved to be stable on non staggered grids and capable of generating accurate non oscillating solutions for two-phase flow calculations.
NASA Technical Reports Server (NTRS)
Jumper, S. J.
1979-01-01
A method was developed for predicting the potential flow velocity field at the plane of a propeller operating under the influence of a wing-fuselage-cowl or nacelle combination. A computer program was written which predicts the three dimensional potential flow field. The contents of the program, its input data, and its output results are described.
NASA Technical Reports Server (NTRS)
Xiques, K. E.; Rawlinson, E. G.; Stalnaker, J. F.; Spradley, L. W.
1982-01-01
A three-dimensional computational technique was used to obtain flowfield solutions to the Euler equations over selected hypersonic missile configurations. The General Interpolants Method (GIM) computer code was used with interpolation functions in an algebraic approach to generate a discrete computational grid for each configuration. The spatial marching version of the GIM code, which treats the parabolized Navier-Stokes (PNS) equations or the Euler equations with a shock capturing, 'MacCormack-like' scheme, was used to advance the solution hyperbolically over each configuration. The inviscid flowfield solutions over the two three-dimensional missile configurations, calculated using the GIM hyperbolic scheme, are presented here. The flow field over a wing/body configuration at zero degree angle of attack is presented. Flow over the fuselage of a tactical missile, termed the TAME 10, at both zero degree and 7.5 degree angles of attack is presented. In addition, an inviscid, two-dimensional analysis of an inlet configuration designed to mount on the TAME 10 is included. Contour maps of velocity and pressure are included for each configuration. Comparison of calculation and data show good agreement.
Fiber pushout test - A three-dimensional finite element computational simulation
NASA Technical Reports Server (NTRS)
Mital, Subodh K.; Chamis, Christos C.
1991-01-01
A fiber pushthrough process was computationally simulated using three-dimensional finite element method. The interface material is replaced by an anisotropic material with greatly reduced shear modulus in order to simulate the fiber pushthrough process using a linear analysis. Such a procedure is easily implemented and is computational very effective. It can be used to predict fiber pushthrough load for a composite system at any temperature. The average interface shear strength obtained from pushthrough load can easily be separated into its two components: one that comes from frictioal stresses and the other that comes from chemical adhesion between fiber and the matrix and mechanical interlocking that develops due to shrinkage of the composite because of phase change during the processing. Step-by-step procedures are described to perform the computational simulation, to establish bounds on interfacial bond strength and to interpret interfacial bond quality.
Efficient computation of the stability of three-dimensional compressible boundary layers
NASA Technical Reports Server (NTRS)
Malik, M. R.; Orszag, S. A.
1981-01-01
Methods for the computer analysis of the stability of three-dimensional compressible boundary layers are discussed and the user-oriented Compressible Stability Analysis (COSAL) computer code is described. The COSAL code uses a matrix finite-difference method for local eigenvalue solution when a good guess for the eigenvalue is available and is significantly more computationally efficient than the commonly used initial-value approach. The local eigenvalue search procedure also results in eigenfunctions and, at little extra work, group velocities. A globally convergent eigenvalue procedure is also developed which may be used when no guess for the eigenvalue is available. The global problem is formulated in such a way that no unstable spurious modes appear so that the method is suitable for use in a black-box stability code. Sample stability calculations are presented for the boundary layer profiles of an LFC swept wing.
Fiber pushout test: A three-dimensional finite element computational simulation
NASA Technical Reports Server (NTRS)
Mital, Subodh K.; Chamis, Christos C.
1990-01-01
A fiber pushthrough process was computationally simulated using three-dimensional finite element method. The interface material is replaced by an anisotropic material with greatly reduced shear modulus in order to simulate the fiber pushthrough process using a linear analysis. Such a procedure is easily implemented and is computationally very effective. It can be used to predict fiber pushthrough load for a composite system at any temperature. The average interface shear strength obtained from pushthrough load can easily be separated into its two components: one that comes from frictional stresses and the other that comes from chemical adhesion between fiber and the matrix and mechanical interlocking that develops due to shrinkage of the composite because of phase change during the processing. Step-by-step procedures are described to perform the computational simulation, to establish bounds on interfacial bond strength and to interpret interfacial bond quality.
Three-dimensional viscous-flow computations using a directionally hybrid implicit-explicit procedure
NASA Astrophysics Data System (ADS)
Rizk, Y. M.; Chaussee, D. S.
A new, directionally dependent, hybrid numerical algorithm for solving the unsteady, three-dimensional Navier-Stokes equations has been developed and used to compute the viscous supersonic flow over complex configurations, which may generate local regions of embedded subsonic or streamwise separated flows or both. The new hybrid implicit-explicit algorithm is derived from the more general implicit Beam-Warming algorithm and is particularly suitable for viscous computations in which the grid spacing in the direction outward from the body is considerably smaller than the spacing in the other two directions. Numerical results obtained from both the hybrid and implicit schemes are presented and compared on the basis of numerical stability, convergence history, and computer and core memory requirements.
An Improved Treatment of External Boundary for Three-Dimensional Flow Computations
NASA Technical Reports Server (NTRS)
Tsynkov, Semyon V.; Vatsa, Veer N.
1997-01-01
We present an innovative numerical approach for setting highly accurate nonlocal boundary conditions at the external computational boundaries when calculating three-dimensional compressible viscous flows over finite bodies. The approach is based on application of the difference potentials method by V. S. Ryaben'kii and extends our previous technique developed for the two-dimensional case. The new boundary conditions methodology has been successfully combined with the NASA-developed code TLNS3D and used for the analysis of wing-shaped configurations in subsonic and transonic flow regimes. As demonstrated by the computational experiments, the improved external boundary conditions allow one to greatly reduce the size of the computational domain while still maintaining high accuracy of the numerical solution. Moreover, they may provide for a noticeable speedup of convergence of the multigrid iterations.
Computational Simulation of Damage Propagation in Three-Dimensional Woven Composites
NASA Technical Reports Server (NTRS)
Huang, Dade; Minnetyan, Levon
2005-01-01
Three dimensional (3D) woven composites have demonstrated multi-directional properties and improved transverse strength, impact resistance, and shear characteristics. The objective of this research is to develop a new model for predicting the elastic constants, hygrothermal effects, thermomechanical response, and stress limits of 3D woven composites; and to develop a computational tool to facilitate the evaluation of 3D woven composite structures with regard to damage tolerance and durability. Fiber orientations of weave and braid patterns are defined with reference to composite structural coordinates. Orthotropic ply properties and stress limits computed via micromechanics are transformed to composite structural coordinates and integrated to obtain the 3D properties. The various stages of degradation, from damage initiation to collapse of structures, in the 3D woven structures are simulated for the first time. Three dimensional woven composite specimens with various woven patterns under different loading conditions, such as tension, compression, bending, and shear are simulated in the validation process of this research. Damage initiation, growth, accumulation, and propagation to fracture are included in these simulations.
Del Grande, N.K.; Dolan, K.W.; Durbin, P.F.; Gorvad, M.R.; Kornblum, B.T.; Perkins, D.E.; Schneberk, D.J.; Shapiro, A.B.
1993-04-01
We discuss three-dimensional (3D) dynamic thermal imaging of structure flaws using dual-band infrared (DBIR) computed tomography. Conventional thermography provides single-band infrared images which are difficult to interpret. Standard procedures yield imprecise (or qualitative) information about subsurface flaw sites which are typically masked by surface clutter. We use a DBIR imaging unique pioneered at LLNL to capture the time history of surface temperature difference for flash-heated targets. We relate these patterns to the location, size, shape and depth of subsurface flaws. We have demonstrated temperature accuracies of 0.2{degree}C, timing synchronizations of 3 ms (after onset of heat flash) and intervals of 42 ms, between images, during an 8 s cooling (and hearing) interval characterizing the front (and back) surface temperature-time history of an epoxy-glue disbond site in a flash-heated aluminum lap joint. This type of disbond played a significant role in causing damage to the Aloha Aircraft fuselage on the aged Boeing 737 jetliner. By ratioing DBIR images (near 5 and 10 micron), we located surface temperature patterns (generated by weak heat flow anomalies at subsurface flaw sites) and removed the emissivity mask (from surface roughness variations). We compared measurements with calculations from the three-dimensional, finite element computer code: TOPAZ3D. We combined infrared, ultrasound and x-ray imaging methods to characterize the lap joint disbond site spatial, bond quality, and material differences.
Three-dimensional computation of mixing of transverse injector in a ducted supersonic airstream
NASA Technical Reports Server (NTRS)
Uenishi, K.; Rogers, R. C.
1986-01-01
Numerical solutions of the three-dimensional mass-averaged elliptic Navier-Stokes equations, including species transport, are obtained for nonreacting, turbulent, mixing flow fields for the case of transverse sonic injection of a secondary gas into a supersonic airstream through a circular orifice injector. Results are presented for flow through a constant area duct and through a duct with a rearward-facing step upstream of the injector. The equations are numerically integrated using MacCormack's explicit method and turbulence is included using the Baldwin-Lomax algebraic eddy viscosity model. In the species transport and energy equations, diffusion coefficients based on Fick's law and an assumption of unit Lewis number are applied. The computations were performed on a CDC-VPS-32 (extended version of Cyber-205) using a grid consisting of approximately 200,000 points. The computed results are compared with experimentally observed penetration and spreading boundaries for an injected gas at two dynamic pressure ratios. Three-dimensional flow field structures are dipicted in terms of static pressure, mass fractions of species and velocity vectors.
Surgical management of impacted teeth using three-dimensional computed tomography.
Costa, Fábio Santos; Bellotti, Alexandre; Farah, Gustavo Jacobucci; Daniel, Aparecido Néri; Camarini, Edevaldo Tadeu; Rezende de Moraes Ferreira, Ana Carulina
2011-11-01
The surgical removal of impacted, supernumerary, or ectopic teeth is a routine procedure to the dental surgeon. Because any and all surgical interventions involve anatomic considerations that predispose the patient to a high risk of incidents or complications, it is absolutely necessary to precisely determine the location of the enclosed teeth, to better plan the procedure. Even though the conventional radiographic techniques are commonly used to detect the presence of such teeth, they can present deficiencies. In those situations, additional examinations can be requested. In this article, we are reporting the case of a 12-year-old patient, whose third superior molars appeared in a very atypical position. We chose to request a computed tomography and three-dimensional manipulation of the obtained images. This article, as its main goal, highlighted the importance of computed tomography and of three-dimensional reconstructions as a tool to precisely determine the location of enclosed teeth, thus allowing for a better planning of the surgery and a safer surgical intervention. PMID:22134273
A systematic computational methodology applied to a three-dimensional film-cooling flowfield
Walters, D.K.; Leylek, J.H.
1997-10-01
Numerical results are presented for a three-dimensional discrete-jet in crossflow problem typical of a realistic film-cooling application in gas turbines. Key aspects of the study include: (1) application of a systematic computational methodology that stresses accurate computational model of the physical problem, including simultaneous, fully elliptic solution of the crossflow, film-hole, and plenum regions; high-quality three-dimensional unstructured grid generation techniques, which have yet to be documented for this class of problems; the use of a high-order discretization scheme to reduce numerical errors significantly; and effective turbulence modeling; (2) a three-way comparison of results to both code validation quality experimental data and a previously documented structured grid simulation; and (3) identification of sources of discrepancy between predicted and measured results, as well as recommendations to alleviate these discrepancies. Solutions were obtained with a multiblock, unstructured/adaptive grid, fully explicit, time-marching, Reynolds-averaged Navier-Stokes code with multigrid, local time stepping, and residual smoothing type acceleration techniques. The computational methodology was applied to the validation test case of a row of discrete jets on a flat plate with a streamwise injection angle of 35 deg, and two film-hole length-to-diameter ratios of 3.5 and 1.75. The density ratio for all cases was 2.0, blowing ratio was varied from 0.5 to 2.0, and free-stream turbulence intensity was 2%. The results demonstrate that the prescribed computational methodology yields consistently more accurate solutions for this class of problems than previous attempts published in the open literature. Sources of disagreement between measured and computed results have been identified, and recommendations made for future prediction of film-cooling problems.
Computation of Three-Dimensional Compressible Flow From a Rectangular Nozzle with Delta Tabs
NASA Technical Reports Server (NTRS)
Reddy, D. R.; Steffen, C. J., Jr.; Zaman, K. B. M. Q.
1999-01-01
A three-dimensional viscous flow analysis is performed using a time-marching Reynolds-averaged Navier-Stokes code for a 3:1 rectangular nozzle with two delta tabs located at the nozz1e exit plane to enhance mixing. Two flow configurations, a subsonic jet case and a supersonic jet case using the same rate configuration, which were previously studied experimentally, are computed and compared with the experimental data. The experimental data include streamwise velocity and vorticity distributions for the subsonic case, and Mach number distributions for the supersonic case, at various axial locations downstream of the nozzle exit. The computational results show very good agreement with the experimental data. In addition, the effect of compressibility on vorticity dynamics is examined by comparing the vorticity contours of the subsonic jet case with those of the supersonic jet case which were not measured in the experiment.
NASA Astrophysics Data System (ADS)
Chiu, Daniel T.; Pezzoli, Elena; Wu, Hongkai; Stroock, Abraham D.; Whitesides, George M.
2001-03-01
This paper describes the design of a parallel algorithm that uses moving fluids in a three-dimensional microfluidic system to solve a nondeterministically polynomial complete problem (the maximal clique problem) in polynomial time. This algorithm relies on (i) parallel fabrication of the microfluidic system, (ii) parallel searching of all potential solutions by using fluid flow, and (iii) parallel optical readout of all solutions. This algorithm was implemented to solve the maximal clique problem for a simple graph with six vertices. The successful implementation of this algorithm to compute solutions for small-size graphs with fluids in microchannels is not useful, per se, but does suggest broader application for microfluidics in computation and control.
Computing three-dimensional eye position quaternions and eye velocity from search coil signals.
Tweed, D; Cadera, W; Vilis, T
1990-01-01
The four-component rotational operators called quaternions, which represent eye rotations in terms of their axes and angles, have several advantages over other representations of eye position (such as Fick coordinates): they provide easy computations, symmetry, a simple form for Listing's law, and useful three-dimensional plots of eye movements. In this paper we present algorithms for computing eye position quaternions and eye angular velocity (not the derivative of position in three dimensions) from two search coils (not necessarily orthogonal) on one eye in two or three magnetic fields, and for locating primary position using quaternions. We show how differentiation of eye position signals yields poor estimates of all three components of eye velocity. PMID:2321369
A computational approach to continuum damping of Alfven waves in two and three-dimensional geometry
Koenies, Axel; Kleiber, Ralf
2012-12-15
While the usual way of calculating continuum damping of global Alfven modes is the introduction of a small artificial resistivity, we present a computational approach to the problem based on a suitable path of integration in the complex plane. This approach is implemented by the Riccati shooting method and it is shown that it can be transferred to the Galerkin method used in three-dimensional ideal magneto-hydrodynamics (MHD) codes. The new approach turns out to be less expensive with respect to resolution and computation time than the usual one. We present an application to large aspect ratio tokamak and stellarator equilibria retaining a few Fourier harmonics only and calculate eigenfunctions and continuum damping rates. These may serve as an input for kinetic MHD hybrid models making it possible to bypass the problem of having singularities on the path of integration on one hand and considering continuum damping on the other.
A comparison of computational methods for three-dimensional, turbulent turbomachinery flow fields
NASA Technical Reports Server (NTRS)
Kirtley, K. R.; Warfield, M.; Lakshminarayana, B.
1986-01-01
A space-marching method and a time-marching method have been used to compute the three-dimensional turbulent flow in an end wall cascade of airfoils. Using an identical grid and turbulence model, the two codes were used to predict a variety of flow quantities. Predictions by the two methods are compared to each other and to experimental data. In general both methods predict measured quantities well, with a small edge in prediction accuracy going to the space-marching method. Secondary flow comparisons show the time-marching solution more accurately predicting the underturning of the flow in the outer portion of the end wall boundary layer while the space-marching method more accurately predicted the overturning of the flow very near the end wall. The prediction comparisons are discussed along with computational details and other attributes of the two methods.
NF85: A three-dimensional, air-dynamics computer code for analyzing explosions in structures
NASA Astrophysics Data System (ADS)
Steinke, R. G.
1987-12-01
The NF85 (Near-Field 85) computer program analyzes the effect of explosions on the dynamic behavior of air in structures. The explosion is modeled as a time- and spallese-dependent source of equivalent air mass and energy. Chemical reactions can be modeled directly with a combustion-model option, and tracer particles may be used to monitor combustion-products convection by the air. The near-field region of the explosion is modeled in three-dimensional Cartesian or cylindrical geometry. Internal structures can be defined in the region to reflect shock waves and obstruct airflow. A convenient dump/restart capability allows the movement or removal of internal structures during the transient solution. The effects of the surrounding far-field region are modeled at the three-dimensional region's external boundary by a wall surface, time- and space-dependent pressure or velocity boundary conditions, and/or one-dimensional Cartesian-geometry regions attached to openings in the external boundary. Ventilation ducts, passageways, and adjacent rooms can be modeled directly with one-dimensional regions, and the presence of blowers and filters can be modeled as well.
The Proteus Navier-Stokes code. [two and three dimensional computational fluid dynamics
NASA Technical Reports Server (NTRS)
Towne, Charles E.; Schwab, John R.
1992-01-01
An effort is currently underway at NASA Lewis to develop two and three dimensional Navier-Stokes codes, called Proteus, for aerospace propulsion applications. Proteus solves the Reynolds-averaged, unsteady, compressible Navier-Stokes equations in strong conservation law form. Turbulence is modeled using a Baldwin-Lomax based algebraic eddy viscosity model. In addition, options are available to solve thin layer or Euler equations, and to eliminate the energy equation by assuming constant stagnation enthalpy. An extensive series of validation cases have been run, primarily using the two dimensional planar/axisymmetric version of the code. Several flows were computed that have exact solution such as: fully developed channel and pipe flow; Couette flow with and without pressure gradients; unsteady Couette flow formation; flow near a suddenly accelerated flat plate; flow between concentric rotating cylinders; and flow near a rotating disk. The two dimensional version of the Proteus code has been released, and the three dimensional code is scheduled for release in late 1991.
NASA Astrophysics Data System (ADS)
Abookasis, David; Rosen, Joseph
2003-08-01
Synthesizing computer-generated holograms (CGHs) of a general three-dimensional (3D) object is usually a heavy computational task. We propose and demonstrate a new algorithm for computing CGHs of 3D objects. In our scheme, many different angular projections of computer-designed 3D objects are numerically processed to yield a single two-dimensional complex matrix. This matrix is equivalent to the complex amplitude of a wave front on the rear focal plane of a spherical lens when the object is located near the front focal point and illuminated by a plane wave. Therefore the computed matrix can be used as a CGH after it is encoded to a real positive-valued transparency. When such CGH is illuminated by a plane wave, a 3D real image of the objects is constructed. The number of computer operations are equivalent to those of a two-dimensional Fourier CGH. Computer and optical constructions of 3D objects, both of which show the feasibility of the proposed approach, are described.
Zhang, Chunhui; Lin, Hui; Chen, Jun; Zhang, Wenwen
2013-01-01
Electrochemical oxidation is a promising technology for the treatment ofbio-refractory wastewater. In this research, advanced treatment of coking wastewater which had previously undergone A/O (anaerobic-aerobic biological) treatment was investigated over Ti/RuO2 x IrO2 anode, stainless steel cathode and coke powder particle electrodes which were packed into the electrodes in a bipolar three-dimensional electrode reactor (BTDR). The results showed that the removal efficiency of COD and ammonia nitrogen increased with applied current density. The main influencing factors of BTDR were evaluated by an orthogonal test, including reaction time, plate distance, current density, plate amounts and aeration flow rate. With reaction time of 60 min, plate distance of 1.0 cm, current density of 20 mA/cm2 and plate amounts of four pairs, most of the contaminants in coking wastewater can be remediated by BTDR, which can then meet the discharge limit for coking wastewater in China. For organic pollutants, 12 kinds of organic pollutants can be completely removed, and the removal efficiencies of 11 kinds of organic pollutants are between 13.3 and 70.3% by advanced treatment with BTDR. We conclude that there is great potential for BTDR in engineering applications as a final treatment for coking wastewater. PMID:24350493
NASA Astrophysics Data System (ADS)
McBride, D.; Cross, M.; Croft, N.; Bennett, C.; Gebhardt, J.
2006-03-01
A computational procedure is presented for solving complex variably saturated flows in porous media, that may easily be implemented into existing conventional finite-volume-based computational fluid dynamics codes, so that their functionality might be geared upon to readily enable the modelling of a complex suite of interacting fluid, thermal and chemical reaction process physics. This procedure has been integrated within a multi-physics finite volume unstructured mesh framework, allowing arbitrarily complex three-dimensional geometries to be modelled. The model is particularly targeted at ore heap-leaching processes, which encounter complex flow problems, such as infiltration into dry soil, drainage, perched water tables and flow through heterogeneous materials, but is equally applicable to any process involving flow through porous media, such as in environmental recovery processes. The computational procedure is based on the mixed form of the classical Richards equation, employing an adaptive transformed mixed algorithm that is numerically robust and significantly reduces compute (or CPU) time. The computational procedure is accurate (compares well with other methods and analytical data), comprehensive (representing any kind of porous flow model), and is computationally efficient. As such, this procedure provides a suitable basis for the implementation of large-scale industrial heap-leach models.
NASA Astrophysics Data System (ADS)
Helfen, L.; Baumbach, T.; Mikulík, P.; Kiel, D.; Pernot, P.; Cloetens, P.; Baruchel, J.
2005-02-01
Computed laminography with synchrotron radiation is developed and carried out for three-dimensional imaging of flat, laterally extended objects with high spatial resolution. Particular experimental conditions of a stationary synchrotron source have been taken into account by a scanning geometry different from that employed with movable conventional laboratory x-ray sources. Depending on the mechanical precision of the sample manipulation system, high spatial resolution down to the scale of 1μm can be attained nondestructively, even for objects of large lateral size. Furthermore, high beam intensity and the parallel-beam geometry enables easy use of monochromatic radiation for optimizing contrast and reducing imaging artifacts. Simulations and experiments on a test object demonstrate the feasibility of the method. Application to the inspection of solder joints in a flip-chip bonded device shows the potential for quality assurance of microsystem devices.
Investigation and evaluation of a computer program to minimize three-dimensional flight time tracks
NASA Technical Reports Server (NTRS)
Parke, F. I.
1981-01-01
The program for the DC 8-D3 flight planning was slightly modified for the three dimensional flight planning for DC 10 aircrafts. Several test runs of the modified program over the North Atlantic and North America were made for verifying the program. While geopotential height and temperature were used in a previous program as meteorological data, the modified program uses wind direction and speed and temperature received from the National Weather Service. A scanning program was written to collect required weather information from the raw data received in a packed decimal format. Two sets of weather data, the 12-hour forecast and 24-hour forecast based on 0000 GMT, are used for dynamic processes in testruns. In order to save computing time only the weather data of the North Atlantic and North America is previously stored in a PCF file and then scanned one by one.
User's manual for PELE3D: a computer code for three-dimensional incompressible fluid dynamics
McMaster, W H
1982-05-07
The PELE3D code is a three-dimensional semi-implicit Eulerian hydrodynamics computer program for the solution of incompressible fluid flow coupled to a structure. The fluid and coupling algorithms have been adapted from the previously developed two-dimensional code PELE-IC. The PELE3D code is written in both plane and cylindrical coordinates. The coupling algorithm is general enough to handle a variety of structural shapes. The free surface algorithm is able to accommodate a top surface and several independent bubbles. The code is in a developmental status since all the intended options have not been fully implemented and tested. Development of this code ended in 1980 upon termination of the contract with the Nuclear Regulatory Commission.
Özkadif, S; Eken, E; Beşoluk, K; Dayan, M. O.
2015-01-01
The aim of this study was to reveal biometric peculiarities of New Zealand white rabbit antebrachium (radius and ulna) by means of three-dimensional (3D) reconstruction of multidetector computed tomography (MDCT) images. Under general anesthesia, the antebrachiums of a total of sixteen rabbits of both sexes were scanned with a general diagnostic MDCT. Biometric measurements of the reconstructed models from high resolution MDCT images were analyzed statistically. Consequently, when biometric measurement values of corresponding bones of antebrachium were compared, it was revealed that there was no statistical significance within both sexes but there were statistically important differences between both sexes in some biometric measurements. It has been suggested that the results from the study can shed light on future studies on the skeletal system and can form a modern point of view to anatomical education. PMID:27175177
Simulation of radiation effects on three-dimensional computer optical memories
NASA Technical Reports Server (NTRS)
Moscovitch, M.; Emfietzoglou, D.
1997-01-01
A model was developed to simulate the effects of heavy charged-particle (HCP) radiation on the information stored in three-dimensional computer optical memories. The model is based on (i) the HCP track radial dose distribution, (ii) the spatial and temporal distribution of temperature in the track, (iii) the matrix-specific radiation-induced changes that will affect the response, and (iv) the kinetics of transition of photochromic molecules from the colored to the colorless isomeric form (bit flip). It is shown that information stored in a volume of several nanometers radius around the particle's track axis may be lost. The magnitude of the effect is dependent on the particle's track structure.
NASA Technical Reports Server (NTRS)
Kutler, P.; Reinhardt, W. A.; Warming, R. F.
1972-01-01
A computational procedure is presented which is capable of determining the supersonic flow field surrounding three-dimensional wing-body configurations such as a delta-wing space shuttle. The governing equations in conservation-law form are solved by a finite difference method using a second-order noncentered algorithm between the body and the outermost shock wave, which is treated as a sharp discontinuity. Secondary shocks which form between these boundaries are captured automatically, and the intersection of these shocks with the bow shock posed no difficulty. Resulting flow fields about typical blunt nose shuttle-like configurations at angle of attack are presented. The differences between perfect and real gas effects for high Mach number flows are shown.
NASA Astrophysics Data System (ADS)
Stürzel, T.; Bieberle, M.; Laurien, E.; Hampel, U.; Barthel, F.; Menz, H.-J.; Mayer, H.-G.
2011-02-01
An experimental facility is described, which has been designed to perform ultrafast two-dimensional (2D) and three-dimensional (3D) electron beam computed tomographies. As a novelty, a specially designed transparent target enables tomography with no axial offset for 2D imaging and high axial resolution 3D imaging employing the cone-beam tomography principles. The imaging speed is 10 000 frames per second for planar scanning and more than 1000 frames per second for 3D imaging. The facility serves a broad spectrum of potential applications; primarily, the study of multiphase flows, but also in principle nondestructive testing or small animal imaging. In order to demonstrate the aptitude for these applications, static phantom experiments at a frame rate of 2000 frames per second were performed. Resulting spatial resolution was found to be 1.2 mm and better for a reduced temporal resolution.
Application of a three-dimensional computational wrist model to proximal row carpectomy.
Wayne, Jennifer S; Mir, Afsarul Q
2015-06-01
A three-dimensional (3D) computational model of the wrist examined the biomechanical effects of the proximal row carpectomy (PRC), a surgical treatment of certain wrist degenerative conditions but with functional consequences. Model simulations, replicating the 3D bony anatomy, soft tissue restraints, muscle loading, and applied perturbations, demonstrated quantitatively accurate responses for the decreased motions subsequent to the surgical procedure. It also yielded some knowledge of alterations in radiocarpal contact force which likely increase contact pressure as well as additional insight into the importance of the triangular fibrocartilage complex and retinacular/capsular structures for stabilizing the deficient wrist. As better understanding of the wrist joint is achieved, this model could serve as a useful clinical tool. PMID:25710135
Three-Dimensional Computed Tomography as a Method for Finding Die Attach Voids in Diodes
NASA Technical Reports Server (NTRS)
Brahm, E. N.; Rolin, T. D.
2010-01-01
NASA analyzes electrical, electronic, and electromechanical (EEE) parts used in space vehicles to understand failure modes of these components. The diode is an EEE part critical to NASA missions that can fail due to excessive voiding in the die attach. Metallography, one established method for studying the die attach, is a time-intensive, destructive, and equivocal process whereby mechanical grinding of the diodes is performed to reveal voiding in the die attach. Problems such as die attach pull-out tend to complicate results and can lead to erroneous conclusions. The objective of this study is to determine if three-dimensional computed tomography (3DCT), a nondestructive technique, is a viable alternative to metallography for detecting die attach voiding. The die attach voiding in two- dimensional planes created from 3DCT scans was compared to several physical cross sections of the same diode to determine if the 3DCT scan accurately recreates die attach volumetric variability
Simulation of radiation effects on three-dimensional computer optical memories
Moscovitch, M.; Emfietzoglou, D.
1997-01-01
A model was developed to simulate the effects of heavy charged-particle (HCP) radiation on the information stored in three-dimensional computer optical memories. The model is based on (i) the HCP track radial dose distribution, (ii) the spatial and temporal distribution of temperature in the track, (iii) the matrix-specific radiation-induced changes that will affect the response, and (iv) the kinetics of transition of photochromic molecules from the colored to the colorless isomeric form (bit flip). It is shown that information stored in a volume of several nanometers radius around the particle{close_quote}s track axis may be lost. The magnitude of the effect is dependent on the particle{close_quote}s track structure. {copyright} {ital 1997 American Institute of Physics.}
Three-Dimensional Object Motion and Velocity Estimation Using a Single Computational RGB-D Camera
Lee, Seungwon; Jeong, Kyungwon; Park, Jinho; Paik, Joonki
2015-01-01
In this paper, a three-dimensional (3D) object moving direction and velocity estimation method is presented using a dual off-axis color-filtered aperture (DCA)-based computational camera. Conventional object tracking methods provided only two-dimensional (2D) states of an object in the image for the target representation. The proposed method estimates depth information in the object region from a single DCA camera that transforms 2D spatial information into 3D model parameters of the object. We also present a calibration method of the DCA camera to estimate the entire set of camera parameters for a practical implementation. Experimental results show that the proposed DCA-based color and depth (RGB-D) camera can calculate the 3D object moving direction and velocity of a randomly moving object in a single-camera framework. PMID:25580899
NASA Technical Reports Server (NTRS)
Walitt, L.; Trulio, J. G.
1971-01-01
A numerical method is presented for the calculation of steady, three-dimensional, viscous, compressible flow fields about slender bodies at angle of attack and at supersonic speeds. Approximations are introduced in modeling the flow in the longitudinal direction. Accordingly, the flow fields calculated with the program were computed with a model that permits viscous crossflow together with inviscid axial flow. An analysis of the errors introduced by such a treatment is presented. Numerical calculations were made and compared with experimental results for an ogive-cylinder and an airplane fuselage configuration. Generally, good agreement with experiment was obtained. However, boundary layer separation and body vortex positions differed from experimental locations on the ogive-cylinder, and the shock induced by the fuselage canopy was predicted at a slightly different location.
The use of computer-generated three-dimensional models in orbital reconstruction.
Perry, M; Banks, P; Richards, R; Friedman, E P; Shaw, P
1998-08-01
In this paper we describe the application of three-dimensional (3D) imaging and computer-generated models in the management of orbital deformity. The technique was found to be particularly useful in posttraumatic deformity and fibrous dysplasia involving the orbit. Further application was found in cases of radiation hypoplasia, high facial cleft, and facial atrophy. Funding restrictions necessitate appropriate selection of cases when using new and expensive 3D imaging rather than traditional and less expensive methods. To remain within a realistic budget only those patients who will clearly benefit from the third dimension compared with traditional methods of assessment and management should be selected. These include patients requiring precise reduction or secondary reconstruction in which there is a matched normal anatomical component for comparison. This application is also only beneficial where the planned reconstruction is dimensionally stable. PMID:9762455
Ambrose, D.H. )
1993-01-01
Using three-dimensional (3-D) graphics computing to evaluate new technologies for computer-assisted mining systems illustrates how these visual techniques can redefine the way researchers look at raw scientific data. The US Bureau of Mines is using 3-D graphics computing to obtain cheaply, easily, and quickly information about the operation and design of current and proposed mechanical coal and metal-nonmetal mining systems. Bureau engineers developed a graphics simulator for a continuous miner that enables a realistic test for experimental software that controls the functions of a machine. Some of the specific simulated functions of the continuous miner are machine motion, appendage motion, machine position, and machine sensors. The simulator uses data files generated in the laboratory or mine using a computer-assisted mining machine. The data file contains information from a laser-based guidance system and a data acquisition system that records all control commands given to a computer-assisted mining machine. This report documents the first phase in developing the simulator and discusses simulator requirements, features of the initial simulator, and several examples of its application. During this endeavor, Bureau engineers discovered and appreciated the simulator's potential to assist their investigations of machine controls and navigation systems.
Advances in three-dimensional integration technologies in support of infrared focal plane arrays
NASA Astrophysics Data System (ADS)
Temple, D. S.; Vick, E. P.; Malta, D.; Lueck, M. R.; Skokan, M. R.; Masterjohn, C. M.; Muzilla, M. S.
2015-01-01
Staring infrared focal plane arrays (FPAs) require pixel-level, three-dimensional (3D) integration with silicon readout integrated circuits (ROICs) that provide detector bias, integrate detector current, and may further process the signals. There is an increased interest in ROIC technology as a result of two trends in the evolution of infrared FPAs. The first trend involves decreasing the FPA pixel size, which leads to the increased information content within the same FPA die size. The second trend involves the desire to enhance signal processing capability at the FPA level, which opens the door to the detector behaving like a smart peripheral rather than a passive component—with complex signal processing functions being executed on, rather than off, the FPA chip. In this paper, we review recent advances in 3D integration process technologies that support these key trends in the development of infrared FPAs. Specifically, we discuss approaches in which the infrared sensor is integrated with 3D ROIC stacks composed of multiple layers of silicon circuitry interconnected using metal-filled through-silicon vias. We describe the continued development of the 3D integration technology and summarize key demonstrations that show its viability for pixels as small as 5 microns.
[Advances in the research of application of hydrogels in three-dimensional bioprinting].
Yang, J; Zhao, Y; Li, H H; Zhu, S H
2016-08-20
Hydrogels are three-dimensional networks made of hydrophilic polymer crosslinked through covalent bonds or physical intermolecular attractions, which can contain growth media and growth factors to support cell growth. In bioprinting, hydrogels are used to provide accurate control over cellular microenvironment and to dramatically reduce experimental repetition times, meanwhile we can obtain three-dimensional cell images of high quality. Hydrogels in three-dimensional bioprinting have received a considerable interest due to their structural similarities to the natural extracellular matrix and polyporous frameworks which can support the cellular proliferation and survival. Meanwhile, they are accompanied by many challenges. PMID:27562161
NASA Technical Reports Server (NTRS)
Marx, Yves P.
1991-01-01
An upwind MUSCL-type implicit scheme for the three-dimensional Navier-Stokes equations is presented and details on the implementation for three-dimensional flows of a 'diagonal' upwind implicit operator are developed. Turbulence models for separated flows are also described with an emphasis on the numerical specificities of the Johnson-King nonequilibrium model. Good predictions of separated two- and three-dimensional flows are demonstrated.
A spectral formalism for computing three-dimensional deformations due to surface loads. 1: Theory
NASA Technical Reports Server (NTRS)
Mitrovica, J. X.; Davis, J. L.; Shapiro, I. I.
1994-01-01
We outline a complete spectral formalism for computing high spatial resolution three-dimensional deformations arising from the surface mass loading of a spherically symmetric planet. The main advantages of the formalism are that all surface mass loads are always described using a consistent mathematical representation and that calculations of deformation fields for various spatial resolutions can be performed by simpley altering the spherical harmonic degree truncation level of the procedure. The latter may be important when incorporating improved observational constraints on a particular surface mass load, when considering potential errors in the computed field associated with mass loading having a spatial scale unresolved by the observational constraints, or when treating a number of global surface mass loads constrained with different spatial resolutions. The advantages do not extend to traditional 'Green's function' approaches which involve surface element discretizations of the global mass loads. Another advantage of the spectral formalism, over the Green's function approach, is that a posteriori analyses of the computed deformation fields are easily performed. In developing the spectral formalism, we consider specific cases where the Earth's mantle is assumed to respond as an elastic, slightly anelastic, or linear viscoelastic medium. In the case of an elastic or slightly anelastic mantle rheology the spectral response equations incorporate frequency dependent Love numbers. The formalism can therefore be used, for example, to compute the potentially resonant deformational response associated with the free core nutation and Chandler wobble eigenfunctions. For completeness, the spectral response equations include both body forces, as arise from the gravitational attraction of the Sun and the Moon, and surface mass loads. In either case, and for both elastic and anelastic mantle rheologies, we outline a pseudo-spectral technique for computing the ocean
External Boundary Conditions for Three-Dimensional Problems of Computational Aerodynamics
NASA Technical Reports Server (NTRS)
Tsynkov, Semyon V.
1997-01-01
We consider an unbounded steady-state flow of viscous fluid over a three-dimensional finite body or configuration of bodies. For the purpose of solving this flow problem numerically, we discretize the governing equations (Navier-Stokes) on a finite-difference grid. The grid obviously cannot stretch from the body up to infinity, because the number of the discrete variables in that case would not be finite. Therefore, prior to the discretization we truncate the original unbounded flow domain by introducing some artificial computational boundary at a finite distance of the body. Typically, the artificial boundary is introduced in a natural way as the external boundary of the domain covered by the grid. The flow problem formulated only on the finite computational domain rather than on the original infinite domain is clearly subdefinite unless some artificial boundary conditions (ABC's) are specified at the external computational boundary. Similarly, the discretized flow problem is subdefinite (i.e., lacks equations with respect to unknowns) unless a special closing procedure is implemented at this artificial boundary. The closing procedure in the discrete case is called the ABC's as well. In this paper, we present an innovative approach to constructing highly accurate ABC's for three-dimensional flow computations. The approach extends our previous technique developed for the two-dimensional case; it employs the finite-difference counterparts to Calderon's pseudodifferential boundary projections calculated in the framework of the difference potentials method (DPM) by Ryaben'kii. The resulting ABC's appear spatially nonlocal but particularly easy to implement along with the existing solvers. The new boundary conditions have been successfully combined with the NASA-developed production code TLNS3D and used for the analysis of wing-shaped configurations in subsonic (including incompressible limit) and transonic flow regimes. As demonstrated by the computational experiments
NASA Technical Reports Server (NTRS)
Guruswamy, P.; Goorjian, P. M.
1982-01-01
Comparisons were made of computed and experimental data in three-dimensional unsteady transonic aerodynamics, including aeroelastic applications. The computer code LTRAN3, which is based on small-disturbance aerodynamic theory, was used to obtain the aerodynamic data. A procedure based on the U-g method was developed to compute flutter boundaries by using the unsteady aerodynamic coefficients obtained from LTRAN3. The experimental data were obtained from available NASA publications. All the studies were conducted for thin, unswept, rectangular wings with circular-arc cross sections. Numerical and experimental steady and unsteady aerodynamic data were compared for a wing with an aspect ratio of 3 and a thickness ratio of 5% at Mach numbers of 0.7 and 0.9. Flutter data were compared for a wing with an aspect ratio of 5. Two thickness ratios, 6% at Mach numbers of 0.715, 0.851, and 0.913, and 4% at Mach number of 0.904, were considered. Based on the unsteady aerodynamic data obtained from LTRAN3, flutter boundaries were computed; they were compared with those obtained from experiments and the code NASTRAN, which uses linear aerodynamics.
Computational models for the analysis of three-dimensional internal and exhaust plume flowfields
NASA Technical Reports Server (NTRS)
Dash, S. M.; Delguidice, P. D.
1977-01-01
This paper describes computational procedures developed for the analysis of three-dimensional supersonic ducted flows and multinozzle exhaust plume flowfields. The models/codes embodying these procedures cater to a broad spectrum of geometric situations via the use of multiple reference plane grid networks in several coordinate systems. Shock capturing techniques are employed to trace the propagation and interaction of multiple shock surfaces while the plume interface, separating the exhaust and external flows, and the plume external shock are discretely analyzed. The computational grid within the reference planes follows the trace of streamlines to facilitate the incorporation of finite-rate chemistry and viscous computational capabilities. Exhaust gas properties consist of combustion products in chemical equilibrium. The computational accuracy of the models/codes is assessed via comparisons with exact solutions, results of other codes and experimental data. Results are presented for the flows in two-dimensional convergent and divergent ducts, expansive and compressive corner flows, flow in a rectangular nozzle and the plume flowfields for exhausts issuing out of single and multiple rectangular nozzles.
NASA Astrophysics Data System (ADS)
Martiniani, Stefano; Schrenk, K. Julian; Stevenson, Jacob D.; Wales, David J.; Frenkel, Daan
2016-01-01
We present a numerical calculation of the total number of disordered jammed configurations Ω of N repulsive, three-dimensional spheres in a fixed volume V . To make these calculations tractable, we increase the computational efficiency of the approach of Xu et al. [Phys. Rev. Lett. 106, 245502 (2011), 10.1103/PhysRevLett.106.245502] and Asenjo et al. [Phys. Rev. Lett. 112, 098002 (2014), 10.1103/PhysRevLett.112.098002] and we extend the method to allow computation of the configurational entropy as a function of pressure. The approach that we use computes the configurational entropy by sampling the absolute volume of basins of attraction of the stable packings in the potential energy landscape. We find a surprisingly strong correlation between the pressure of a configuration and the volume of its basin of attraction in the potential energy landscape. This relation is well described by a power law. Our methodology to compute the number of minima in the potential energy landscape should be applicable to a wide range of other enumeration problems in statistical physics, string theory, cosmology, and machine learning that aim to find the distribution of the extrema of a scalar cost function that depends on many degrees of freedom.
Martiniani, Stefano; Schrenk, K Julian; Stevenson, Jacob D; Wales, David J; Frenkel, Daan
2016-01-01
We present a numerical calculation of the total number of disordered jammed configurations Ω of N repulsive, three-dimensional spheres in a fixed volume V. To make these calculations tractable, we increase the computational efficiency of the approach of Xu et al. [Phys. Rev. Lett. 106, 245502 (2011)10.1103/PhysRevLett.106.245502] and Asenjo et al. [Phys. Rev. Lett. 112, 098002 (2014)10.1103/PhysRevLett.112.098002] and we extend the method to allow computation of the configurational entropy as a function of pressure. The approach that we use computes the configurational entropy by sampling the absolute volume of basins of attraction of the stable packings in the potential energy landscape. We find a surprisingly strong correlation between the pressure of a configuration and the volume of its basin of attraction in the potential energy landscape. This relation is well described by a power law. Our methodology to compute the number of minima in the potential energy landscape should be applicable to a wide range of other enumeration problems in statistical physics, string theory, cosmology, and machine learning that aim to find the distribution of the extrema of a scalar cost function that depends on many degrees of freedom. PMID:26871142
High Speed Data Acquisition System for Three-Dimensional X-Ray and Neutron Computed Tomography
Davis, A.W.; Claytor, T.N.; Sheats, M.J.
1999-07-01
Computed tomography for nondestructive evaluation applications has been limited by system cost, resolution, and time requirements for three-dimensional data sets. FlashCT (Flat panel Amorphous Silicon High-Resolution Computed Tomography) is a system developed at Los Alamos National Laboratory to address these three problems. Developed around a flat panel amorphous silicon detector array, FlashCT is suitable for low to medium energy x-ray and neutron computed tomography at 127-micron resolution. Overall system size is small, allowing rapid transportation to a variety of radiographic sources. System control software was developed in LabVIEW for Windows NT to allow multithreading of data acquisition, data correction, and staging motor control. The system control software simplifies data collection and allows fully automated control of the data acquisition process, leading toward remote or unattended operation. The first generation of the FlashCT Data Acquisition System was completed in Au gust 1998, and since that time the system has been tested using x-ray sources ranging in energy from 60 kV to 20MV. The system has also been used to collect data for thermal neutron computed tomography at Los Alamos Neutron Science Center (LANSCE). System improvements have been proposed to provide faster data collection and greater dynamic range during data collection.
Vortical flow in human elbow joints: a three-dimensional computed tomography modeling study.
Adikrishna, Arnold; Kekatpure, Aashay L; Tan, Jun; Lee, Hyun-Joo; Deslivia, Maria Florencia; Jeon, In-Ho
2014-10-01
The human elbow joint has been regarded as a loose hinge joint, with a unique helical motion of the axis during extension-flexion. This study was designed to identify the helical axis in the ulnohumeral joint during elbow extension-flexion by tracking the midpoint between the coronoid tip and the olecranon tip of the proximal ulna in a three-dimensional (3D) computed tomography (CT) image model. The elbows of four volunteers were CT-scanned at four flexion angles (0°, 45°, 90°, and 130°) at neutral rotation with a custom-made holding device to control any motion during scanning. Three-dimensional models of each elbow were reconstructed and a 3D ulnohumeral joint at 45°, 90°, and 130° was superimposed onto a fully extended joint (0°) by rotating and translating each 3D ulnohumeral joint along the axes. The midpoints of the olecranon and coronoid tips were interpolated using cubic spline technique and the dynamic elbow motion was plotted to determine the motion of the helical axis. The means and standard deviations were subsequently calculated. The average midpoint pattern of joint motion from extension to flexion was elliptical-orbit-like when projected onto a sagittal plane and continuously translated a mean 2.14 ± 0.34 mm (range, 1.83-2.52 mm) to the lateral side during elbow extension-flexion. In 3D space, the average midpoint pattern of the ulnohumeral joint resembles a vortical flow, spinning along an imaginary axis, with an inconsistent radius from 0° to 130° flexion. The ulnohumeral joint axis both rotates and translates during elbow extension-flexion, with a vortex-flow motion occurring during flexion in 3D model analysis. This motion should be considered when performing hinged external fixation, total elbow replacement and medial collateral ligament reconstruction surgery. PMID:25100632
NASA Astrophysics Data System (ADS)
Liu, P.; Zhang, Y.
2008-04-01
Accurately simulating secondary organic aerosols (SOA) in three-dimensional (3-D) air quality models is challenging due to the complexity of the physics and chemistry involved and the high computational demand required. A computationally-efficient yet accurate SOA module is necessary in 3-D applications for long-term simulations and real-time air quality forecasting. A coupled gas and aerosol box model (i.e., 0-D CMAQ-MADRID 2) is used to optimize relevant processes in order to develop such a SOA module. Solving the partitioning equations for condensable volatile organic compounds (VOCs) and calculating their activity coefficients in the multicomponent mixtures are identified to be the most computationally-expensive processes. The two processes can be speeded up by relaxing the error tolerance levels and reducing the maximum number of iterations of the numerical solver for the partitioning equations for organic species; turning on organic-inorganic interactions only when the water content associated with organic compounds is significant; and parameterizing the calculation of activity coefficients for organic mixtures in the hydrophilic module. The optimal speed-up method can reduce the total CPU cost by up to a factor of 29.7 with ±15% deviation from benchmark results. These speedup methods are applicable to other SOA modules that are based on partitioning theories.
NASA Astrophysics Data System (ADS)
Liu, P.; Zhang, Y.
2008-07-01
Accurately simulating secondary organic aerosols (SOA) in three-dimensional (3-D) air quality models is challenging due to the complexity of the physics and chemistry involved and the high computational demand required. A computationally-efficient yet accurate SOA module is necessary in 3-D applications for long-term simulations and real-time air quality forecasting. A coupled gas and aerosol box model (i.e., 0-D CMAQ-MADRID 2) is used to optimize relevant processes in order to develop such a SOA module. Solving the partitioning equations for condensable volatile organic compounds (VOCs) and calculating their activity coefficients in the multicomponent mixtures are identified to be the most computationally-expensive processes. The two processes can be speeded up by relaxing the error tolerance levels and reducing the maximum number of iterations of the numerical solver for the partitioning equations for organic species; conditionally activating organic-inorganic interactions; and parameterizing the calculation of activity coefficients for organic mixtures in the hydrophilic module. The optimal speed-up method can reduce the total CPU cost by up to a factor of 31.4 from benchmark under the rural conditions with 2 ppb isoprene and by factors of 10 71 under various test conditions with 2 10 ppb isoprene and >40% relative humidity while maintaining ±15% deviation. These speed-up methods are applicable to other SOA modules that are based on partitioning theories.
Constructing three-dimensional detachable and composable computer models of the head and neck.
Fan, Min; Dai, Peishan; Zheng, Buhong; Li, Xinchun
2015-06-01
The head and neck region has a complex spatial and topological structure, three-dimensional (3D) computer model of the region can be used in anatomical education, radiotherapy planning and surgical training. However, most of the current models only consist of a few parts of the head and neck, and the 3D models are not detachable and composable. In this study, a high-resolution 3D detachable and composable model of the head and neck was constructed based on computed tomography (CT) serial images. First, fine CT serial images of the head and neck were obtained. Then, a color lookup table was created for 58 structures, which was used to create anatomical atlases of the head and neck. Then, surface and volume rendering methods were used to reconstruct 3D models of the head and neck. Smoothing and polygon reduction steps were added to improve 3D rendering effects. 3D computer models of the head and neck, including the sinus, pharynx, vasculature, nervous system, endocrine system and glands, muscles, bones and skin, were reconstructed. The models consisted of 58 anatomical detachable and composable structures and each structure can be displayed individually or together with other structures. PMID:26091713
Application of three-dimensional computer modeling for reservoir and ore-body analysis
Hamilton, D.E.; Marie, J.L.; Moon, G.M.; Moretti, F.J.; Ryman, W.P.; Didur, R.S.
1985-02-01
Three-dimensional computer modeling of reservoirs and ore bodies aids in understanding and exploiting these resources. This modeling tool enables the geologist and engineer to correlate in 3 dimensions, experiment with various geologic interpretations, combine variables to enhance certain geologic attributes, test for reservoir heterogeneities and continuity, select drill sites or perforation zones, determine volumes, plan production, generate geologic parameters for input to flow simulators, calculate tonnages and ore-waste ratios, and test sensitivity of reserves to various ore-grade cutoffs and economic parameters. All applications benefit from the ability to update rapidly the 3-dimensional computer models when new data are collected. Two 3-dimensional computer modeling projects demonstrate these capabilities. The first project involves modeling porosity, permeability, and water saturation in a Malaysian reservoir. The models were used to analyze the relationship between water saturation and porosity and to generate geologic parameters for input to a flow simulator. The second project involves modeling copper, zinc, silver, gold, and specific gravity in a massive sulfide ore body in British Columbia. The 4 metal models were combined into one copper-equivalence model and evaluated for tonnage, stripping ratio, and sensitivity to variations of ore-grade cutoff.
Wieringa, Fokko P.; Bouma, Henri; Eendebak, Pieter T.; van Basten, Jean-Paul A.; Beerlage, Harrie P.; Smits, Geert A. H. J.; Bos, Jelte E.
2014-01-01
Abstract. In comparison to open surgery, endoscopic surgery offers impaired depth perception and narrower field-of-view. To improve depth perception, the Da Vinci robot offers three-dimensional (3-D) video on the console for the surgeon but not for assistants, although both must collaborate. We improved the shared perception of the whole surgical team by connecting live 3-D monitors to all three available Da Vinci generations, probed user experience after two years by questionnaire, and compared time measurements of a predefined complex interaction task performed with a 3-D monitor versus two-dimensional. Additionally, we investigated whether the complex mental task of reconstructing a 3-D overview from an endoscopic video can be performed by a computer and shared among users. During the study, 925 robot-assisted laparoscopic procedures were performed in three hospitals, including prostatectomies, cystectomies, and nephrectomies. Thirty-one users participated in our questionnaire. Eighty-four percent preferred 3-D monitors and 100% reported spatial-perception improvement. All participating urologists indicated quicker performance of tasks requiring delicate collaboration (e.g., clip placement) when assistants used 3-D monitors. Eighteen users participated in a timing experiment during a delicate cooperation task in vitro. Teamwork was significantly (40%) faster with the 3-D monitor. Computer-generated 3-D reconstructions from recordings offered very wide interactive panoramas with educational value, although the present embodiment is vulnerable to movement artifacts. PMID:26158026
NASA Astrophysics Data System (ADS)
Zhang, Hao; Tan, Qiaofeng; Jin, Guofan
2013-02-01
Holographic display is capable of reconstructing the whole optical wave field of a three-dimensional (3D) scene. It is the only one among all the 3D display techniques that can produce all the depth cues. With the development of computing technology and spatial light modulators, computer generated holograms (CGHs) can now be used to produce dynamic 3D images of synthetic objects. Computation holography becomes highly complicated and demanding when it is employed to produce real 3D images. Here we present a novel algorithm for generating a full parallax 3D CGH with occlusion effect, which is an important property of 3D perception, but has often been neglected in fully computed hologram synthesis. The ray casting technique, which is widely used in computer graphics, is introduced to handle the occlusion issue of CGH computation. Horizontally and vertically distributed rays are projected from each hologram sample to the 3D objects to obtain the complex amplitude distribution. The occlusion issue is handled by performing ray casting calculations to all the hologram samples. The proposed algorithm has no restriction on or approximation to the 3D objects, and hence it can produce reconstructed images with correct shading effect and no visible artifacts. Programmable graphics processing unit (GPU) is used to perform parallel calculation. This is made possible because each hologram sample belongs to an independent operation. To demonstrate the performance of our proposed algorithm, an optical experiment is performed to reconstruct the 3D scene by using a phase-only spatial light modulator. We can easily perceive the accommodation cue by focusing our eyes on different depths of the scene and the motion parallax cue with occlusion effect by moving our eyes around. The experiment result confirms that the CGHs produced by our algorithm can successfully reconstruct 3D images with all the depth cues.
Synchrotron X-ray computed laminography of the three-dimensional anatomy of tomato leaves.
Verboven, Pieter; Herremans, Els; Helfen, Lukas; Ho, Quang T; Abera, Metadel; Baumbach, Tilo; Wevers, Martine; Nicolaï, Bart M
2015-01-01
Synchrotron radiation computed laminography (SR-CL) is presented as an imaging method for analyzing the three-dimensional (3D) anatomy of leaves. The SR-CL method was used to provide 3D images of 1-mm² samples of intact leaves at a pixel resolution of 750 nm. The method allowed visualization and quantitative analysis of palisade and spongy mesophyll cells, and showed local venation patterns, aspects of xylem vascular structure and stomata. The method failed to image subcellular organelles such as chloroplasts. We constructed 3D computer models of leaves that can provide a basis for calculating gas exchange, light penetration and water and solute transport. The leaf anatomy of two different tomato genotypes grown in saturating light conditions was compared by 3D analysis. Differences were found in calculated values of tissue porosity, cell number density, cell area to volume ratio and cell volume and cell shape distributions of palisade and spongy cell layers. In contrast, the exposed cell area to leaf area ratio in mesophyll, a descriptor that correlates to the maximum rate of photosynthesis in saturated light conditions, was no different between spongy and palisade cells or between genotypes. The use of 3D image processing avoids many of the limitations of anatomical analysis with two-dimensional sections. PMID:25319143
Hasegawa, T; Horio, H; Okino, H; Taylor, T W; Yamaguchi, T
1993-01-01
An application of three-dimensional (3D) computational fluid mechanics to the air flow in infant incubators is presented. The air flows in two numerical models were simulated by directly solving the Navier-Stokes equations for incompressible gases. The method used was a finite-volume method incorporating a body-fitted coordinate system. The basic model was based on a real infant incubator, which was slightly simplified and included a model of a baby. The number of computation grids was 56 (width) x 21 (depth) x 21 (height) = 24,696. There were several very-large-scale eddies in the incubator free space. In addition to the global structure, small-scale eddies were shown to be produced at many locations scattered in the free space. From these results, it is evident that the conventional assumption of steady and uniform flows in incubators is not always justified when considering heat loss from the body of a baby in an incubator. PMID:8369866
Acosta Santamaría, Víctor Andrés; Malvè, M; Duizabo, A; Mena Tobar, A; Gallego Ferrer, G; García Aznar, J M; Doblaré, M; Ochoa, I
2013-11-01
The application of three-dimensional (3D) biomaterials to facilitate the adhesion, proliferation, and differentiation of cells has been widely studied for tissue engineering purposes. The fabrication methods used to improve the mechanical response of the scaffold produce complex and non regular structures. Apart from the mechanical aspect, the fluid behavior in the inner part of the scaffold should also be considered. Parameters such as permeability (k) or wall shear stress (WSS) are important aspects in the provision of nutrients, the removal of metabolic waste products or the mechanically-induced differentiation of cells attached in the trabecular network of the scaffolds. Experimental measurements of these parameters are not available in all labs. However, fluid parameters should be known prior to other types of experiments. The present work compares an experimental study with a computational fluid dynamics (CFD) methodology to determine the related fluid parameters (k and WSS) of complex non regular poly(L-lactic acid) scaffolds based only on the treatment of microphotographic images obtained with a microCT (μCT). The CFD analysis shows similar tendencies and results with low relative difference compared to those of the experimental study, for high flow rates. For low flow rates the accuracy of this prediction reduces. The correlation between the computational and experimental results validates the robustness of the proposed methodology. PMID:23807712
Xue, Qian; Zheng, Xudong; Mittal, Rajat; Bielamowicz, Steve
2014-01-01
Summary Objective The current study explores the use of a continuum based computational model to investigate the effect of left right tension imbalance on vocal fold vibrations and glottal aerodynamics, as well as its implication on phonation. The study allows us to gain new insights into the underlying physical mechanism of irregularities induced by vocal fold tension imbalance associated with unilateral cricothyroid muscle paralysis. Method A three dimensional simulation of glottal flow and vocal fold dynamics in a tubular laryngeal model with tension imbalance was conducted by using a coupled flow-structure interaction computational model. Tension imbalance was modeled by reducing by 20% the Young’s modulus of one of the vocal folds, while holding vocal fold length constant. Effects of tension imbalance on vibratory characteristic of the vocal folds and on the time-varying properties of glottal airflow as well as the aerodynamic energy transfer are comprehensively analyzed. Results and Conclusions The analysis demonstrates that the continuum based biomechanical model can provide a good description of phonatory dynamics in tension imbalance conditions. It is found that while 20% tension imbalance does not have noticeable effects on the fundamental frequency, it does lead to a larger glottal flow leakage and asymmetric vibrations of the two vocal folds. A detailed analysis of the energy transfer suggests that the majority of the energy is consumed by the lateral motion of the vocal folds and the net energy transferred to the softer fold is less than the one transferred to the normal fold. PMID:24725589
Three-Dimensional Computational Fluid Dynamics Modeling of Solid Oxide Electrolysis Cells and Stacks
Grant Hawkes; James O'Brien; Carl Stoots; Stephen Herring
2008-07-01
A three-dimensional computational fluid dynamics (CFD) electrochemical model has been created for detailed analysis of a high-temperature electrolysis stack (solid oxide fuel cells operated as electrolyzers). Inlet and outlet plenum flow distributions are discussed. Maldistribution of plena flow show deviations in per-cell operating conditions due to non-uniformity of species concentrations. Models have also been created to simulate experimental conditions and for code validation. Comparisons between model predictions and experimental results are discussed. Mass, momentum, energy, and species conservation and transport are provided via the core features of the commercial CFD code FLUENT. A solid-oxide fuel cell (SOFC) model adds the electrochemical reactions and loss mechanisms and computation of the electric field throughout the cell. The FLUENT SOFC user-defined subroutine was modified for this work to allow for operation in the electrolysis mode. Model results provide detailed profiles of temperature, Nernst potential, operating potential, activation over-potential, anode-side gas composition, cathode-side gas composition, current density and hydrogen production over a range of stack operating conditions. Variations in flow distribution, and species concentration are discussed. End effects of flow and per-cell voltage are also considered. Predicted mean outlet hydrogen and steam concentrations vary linearly with current density, as expected. Contour plots of local electrolyte temperature, current density, and Nernst potential indicate the effects of heat transfer, reaction cooling/heating, and change in local gas composition.
Full parallax three-dimensional display with occlusion effect using computer generated hologram
NASA Astrophysics Data System (ADS)
Zhang, Hao; Collings, Neil; Chen, Jing; Crossland, Bill; Chu, Daping; Xie, Jinghui
2011-07-01
Computational holography becomes highly complicated and demanding when it is employed to produce real three-dimensional (3D) images. Here we present a novel algorithm for generating a full parallax 3D computer generated hologram (CGH) with occlusion effect, which is an important property of 3D perception, but has often been neglected in most CGH related works. The ray casting technique is introduced to handle the occlusion issue. Horizontally and vertically distributed rays are projected from each hologram sample to the 3D objects to obtain the complex amplitude distribution. The proposed algorithm has no restriction on--or approximation to--the 3D objects, and it can produce reconstructed images with correct shading effect and no visible artifacts. An optical experiment is performed to validate our approach, using a phase-only spatial light modulator to optically reconstruct a 3D scene. The experimental result confirmed that the CGHs produced by our algorithm can successfully reconstruct 3D images with full parallax and occlusion effect.
Computation of three-dimensional nozzle-exhaust flow fields with the GIM code
NASA Technical Reports Server (NTRS)
Spradley, L. W.; Anderson, P. G.
1978-01-01
A methodology is introduced for constructing numerical analogs of the partial differential equations of continuum mechanics. A general formulation is provided which permits classical finite element and many of the finite difference methods to be derived directly. The approach, termed the General Interpolants Method (GIM), can combined the best features of finite element and finite difference methods. A quasi-variational procedure is used to formulate the element equations, to introduce boundary conditions into the method and to provide a natural assembly sequence. A derivation is given in terms of general interpolation functions from this procedure. Example computations for transonic and supersonic flows in two and three dimensions are given to illustrate the utility of GIM. A three-dimensional nozzle-exhaust flow field is solved including interaction with the freestream and a coupled treatment of the shear layer. Potential applications of the GIM code to a variety of computational fluid dynamics problems is then discussed in terms of existing capability or by extension of the methodology.
NASA Astrophysics Data System (ADS)
Kinoshita, Shunichi; Eder, Wolfgang; Woeger, Julia; Hohenegger, Johann; Briguglio, Antonino; Ferrandez-Canadell, Carles
2015-04-01
Symbiont-bearing larger benthic Foraminifera (LBF) are long-living marine (at least 1 year), single-celled organisms with complex calcium carbonate shells. Their morphology has been intensively studied since the middle of the nineteenth century. This led to a broad spectrum of taxonomic results, important from biostratigraphy to ecology in shallow water tropical to warm temperate marine palaeo-environments. However, it was necessary for the traditional investigation methods to cut or destruct specimens for analysing the taxonomically important inner structures. X-ray micro-computed tomography (microCT) is one of the newest techniques used in morphological studies. The greatest advantage is the non-destructive acquisition of inner structures. Furthermore, the running improve of microCT scanners' hard- and software provides high resolution and short time scans well-suited for LBF. Three-dimensional imaging techniques allow to select and extract each chamber and to measure easily its volume, surface and several form parameters used for morphometric analyses. Thus, 3-dimensional visualisation of LBF-tests is a very big step forward from traditional morphology based on 2-dimensional data. The quantification of chamber form is a great opportunity to tackle LBF structures, architectures and the bauplan geometry. The micrometric digital resolution is the only way to solve many controversies in phylogeny and evolutionary trends of LBF. For the present study we used micro-computed tomography to easily investigate the chamber number of every specimen from statistically representative part of populations to estimate population dynamics. Samples of living individuals are collected at monthly intervals from fixed locations. Specific preparation allows to scan up to 35 specimens per scan within 2 hours and to obtain the complete digital dataset for each specimen of the population. MicroCT enables thus a fast and precise count of all chambers built by the foraminifer from its
Optical computed tomography of radiochromic gels for accurate three-dimensional dosimetry
NASA Astrophysics Data System (ADS)
Babic, Steven
In this thesis, three-dimensional (3-D) radiochromic Ferrous Xylenol-orange (FX) and Leuco Crystal Violet (LCV) micelles gels were imaged by laser and cone-beam (Vista(TM)) optical computed tomography (CT) scanners. The objective was to develop optical CT of radiochromic gels for accurate 3-D dosimetry of intensity-modulated radiation therapy (IMRT) and small field techniques used in modern radiotherapy. First, the cause of a threshold dose response in FX gel dosimeters when scanned with a yellow light source was determined. This effect stems from a spectral sensitivity to multiple chemical complexes that are at different dose levels between ferric ions and xylenol-orange. To negate the threshold dose, an initial concentration of ferric ions is needed in order to shift the chemical equilibrium so that additional dose results in a linear production of a coloured complex that preferentially absorbs at longer wavelengths. Second, a low diffusion leuco-based radiochromic gel consisting of Triton X-100 micelles was developed. The diffusion coefficient of the LCV micelle gel was found to be minimal (0.036 + 0.001 mm2 hr-1 ). Although a dosimetric characterization revealed a reduced sensitivity to radiation, this was offset by a lower auto-oxidation rate and base optical density, higher melting point and no spectral sensitivity. Third, the Radiological Physics Centre (RPC) head-and-neck IMRT protocol was extended to 3-D dose verification using laser and cone-beam (Vista(TM)) optical CT scans of FX gels. Both optical systems yielded comparable measured dose distributions in high-dose regions and low gradients. The FX gel dosimetry results were crossed checked against independent thermoluminescent dosimeter and GAFChromicRTM EBT film measurements made by the RPC. It was shown that optical CT scanned FX gels can be used for accurate IMRT dose verification in 3-D. Finally, corrections for FX gel diffusion and scattered stray light in the Vista(TM) scanner were developed to
Shimizu, Y; Kamiyoshihara, M; Okajo, J; Ishii, Y; Takise, A
2014-01-01
Patients with relapsing polychondritis (RP) and airway stenosis have difficulty performing conventional spirometry that requires maximum forced expiration. We report a patient with RP who showed progressive severe bronchial stenosis on three-dimensional computed tomography (3D-CT) and impulse oscillation (IOS) with 3D color imaging using a Mostgraph®. The forced oscillation technique using IOS allows within-breath evaluation without forced expiration. A 68-year-old man who had RP presented with dyspnea due to stenosis of the trachea and left main bronchus (lt. mb). Stenting was performed twice in two years. Chest 3D-CT revealed a marked difference in the extent of bronchial collapse during expiration compared with inspiration. The forced expiratory volume in 1 second (FEV1.0), reactance at 5Hz (X5), resonant frequency (Fres), and integrated low frequency reactance area (ALX) measured by IOS showed temporary improvement after placement of the first stent, but respiratory resistance at 5Hz (R5) and 20Hz (R20) remained poor. 3D color images of respiratory resistance obtained with a Mostgraph® already showed high values at the time of diagnosis, resembling the features of chronic obstructive disease (COPD). 3D color images were helpful for interpreting the changes of IOS parameters during the clinical course. In conclusion, 3D-CT in inspiration/expiration and noninvasive IOS with 3D color imaging are useful for assessing airway stenosis in RP while reducing the burden of repeated spirometry. PMID:25001664
Three-Dimensional Effects in Multi-Element High Lift Computations
NASA Technical Reports Server (NTRS)
Rumsey, Christopher L.; LeeReusch, Elizabeth M.; Watson, Ralph D.
2003-01-01
In an effort to discover the causes for disagreement between previous two-dimensional (2-D) computations and nominally 2-D experiment for flow over the three-element McDonnell Douglas 30P-30N airfoil configuration at high lift, a combined experimental/CFD investigation is described. The experiment explores several different side-wall boundary layer control venting patterns, documents venting mass flow rates, and looks at corner surface flow patterns. The experimental angle of attack at maximum lift is found to be sensitive to the side-wall venting pattern: a particular pattern increases the angle of attack at maximum lift by at least 2 deg. A significant amount of spanwise pressure variation is present at angles of attack near maximum lift. A CFD study using three-dimensional (3-D) structured-grid computations, which includes the modeling of side-wall venting, is employed to investigate 3-D effects on the flow. Side-wall suction strength is found to affect the angle at which maximum lift is predicted. Maximum lift in the CFD is shown to be limited by the growth of an off-body corner flow vortex and consequent increase in spanwise pressure variation and decrease in circulation. The 3-D computations with and without wall venting predict similar trends to experiment at low angles of attack, but either stall too early or else overpredict lift levels near maximum lift by as much as 5%. Unstructured-grid computations demonstrate that mounting brackets lower the lift levels near maximum lift conditions.
Computational Aerodynamic Analysis of Three-Dimensional Ice Shapes on a NACA 23012 Airfoil
NASA Technical Reports Server (NTRS)
Jun, Garam; Oliden, Daniel; Potapczuk, Mark G.; Tsao, Jen-Ching
2014-01-01
The present study identifies a process for performing computational fluid dynamic calculations of the flow over full three-dimensional (3D) representations of complex ice shapes deposited on aircraft surfaces. Rime and glaze icing geometries formed on a NACA23012 airfoil were obtained during testing in the NASA Glenn Research Center's Icing Research Tunnel (IRT). The ice shape geometries were scanned as a cloud of data points using a 3D laser scanner. The data point clouds were meshed using Geomagic software to create highly accurate models of the ice surface. The surface data was imported into Pointwise grid generation software to create the CFD surface and volume grids. It was determined that generating grids in Pointwise for complex 3D icing geometries was possible using various techniques that depended on the ice shape. Computations of the flow fields over these ice shapes were performed using the NASA National Combustion Code (NCC). Results for a rime ice shape for angle of attack conditions ranging from 0 to 10 degrees and for freestream Mach numbers of 0.10 and 0.18 are presented. For validation of the computational results, comparisons were made to test results from rapid-prototype models of the selected ice accretion shapes, obtained from a separate study in a subsonic wind tunnel at the University of Illinois at Urbana-Champaign. The computational and experimental results were compared for values of pressure coefficient and lift. Initial results show fairly good agreement for rime ice accretion simulations across the range of conditions examined. The glaze ice results are promising but require some further examination.
Computational Aerodynamic Analysis of Three-Dimensional Ice Shapes on a NACA 23012 Airfoil
NASA Technical Reports Server (NTRS)
Jun, GaRam; Oliden, Daniel; Potapczuk, Mark G.; Tsao, Jen-Ching
2014-01-01
The present study identifies a process for performing computational fluid dynamic calculations of the flow over full three-dimensional (3D) representations of complex ice shapes deposited on aircraft surfaces. Rime and glaze icing geometries formed on a NACA23012 airfoil were obtained during testing in the NASA Glenn Research Centers Icing Research Tunnel (IRT). The ice shape geometries were scanned as a cloud of data points using a 3D laser scanner. The data point clouds were meshed using Geomagic software to create highly accurate models of the ice surface. The surface data was imported into Pointwise grid generation software to create the CFD surface and volume grids. It was determined that generating grids in Pointwise for complex 3D icing geometries was possible using various techniques that depended on the ice shape. Computations of the flow fields over these ice shapes were performed using the NASA National Combustion Code (NCC). Results for a rime ice shape for angle of attack conditions ranging from 0 to 10 degrees and for freestream Mach numbers of 0.10 and 0.18 are presented. For validation of the computational results, comparisons were made to test results from rapid-prototype models of the selected ice accretion shapes, obtained from a separate study in a subsonic wind tunnel at the University of Illinois at Urbana-Champaign. The computational and experimental results were compared for values of pressure coefficient and lift. Initial results show fairly good agreement for rime ice accretion simulations across the range of conditions examined. The glaze ice results are promising but require some further examination.
Valentini, Anna Lia; Gui, Benedetta; D'Agostino, Giuseppe Roberto; Mattiucci, Giancarlo; Clementi, Valeria; Di Molfetta, Ippolita Valentina; Bonomo, Pierluigi; Mantini, Giovanna
2012-11-01
Purpose: To correlate results of three-dimensional magnetic resonance spectroscopic imaging (MRSI) with prostate-specific antigen (PSA) levels and time since external beam irradiation (EBRT) in patients treated with long-term hormone therapy (HT) and EBRT for locally advanced disease to verify successful treatment by documenting the achievement of metabolic atrophy (MA). Methods and Materials: Between 2006 and 2008, 109 patients were consecutively enrolled. MA was assessed by choline and citrate peak area-to-noise-ratio <5:1. Cancerous metabolism (CM) was defined by choline-to-creatine ratio >1.5:1 or choline signal-to-noise-ratio >5:1. To test the strength of association between MRSI results and the time elapsed since EBRT (TEFRT), PSA levels, Gleason score (GS), and stage, logistic regression (LR) was performed. p value <0.05 was statistically significant. The patients' outcomes were verified in 2011. Results: MRSI documented MA in 84 of 109 and CM in 25 of 109 cases. LR showed that age, GS, stage, and initial and recent PSA had no significant impact on MRSI results which were significantly related to PSA values at the time of MRSI and to TEFRT. Patients were divided into three groups according to TEFRT: <1 year, 1-2 years, and >2 years. MA was detected in 54.1% of patients of group 1, 88.9% of group 2, and in 94.5% of group 3 (100% when PSA nadir was reached). CM was detected in 50% of patients with reached PSA nadir in group 1. Local relapse was found in 3 patients previously showing CM at long TEFRT. Conclusion: MA detection, indicative of successful treatment because growth of normal or abnormal cells cannot occur without metabolism, increases with decreasing PSA levels and increasing time on HT after EBRT. This supports long-term HT in advanced prostate cancer. Larger study series are needed to assess whether MRSI could predict local relapse by detecting CM at long TEFRT.
A computational model to generate simulated three-dimensional breast masses
de Sisternes, Luis; Brankov, Jovan G.; Zysk, Adam M.; Schmidt, Robert A.; Nishikawa, Robert M.; Wernick, Miles N.
2015-01-01
Purpose: To develop algorithms for creating realistic three-dimensional (3D) simulated breast masses and embedding them within actual clinical mammograms. The proposed techniques yield high-resolution simulated breast masses having randomized shapes, with user-defined mass type, size, location, and shape characteristics. Methods: The authors describe a method of producing 3D digital simulations of breast masses and a technique for embedding these simulated masses within actual digitized mammograms. Simulated 3D breast masses were generated by using a modified stochastic Gaussian random sphere model to generate a central tumor mass, and an iterative fractal branching algorithm to add complex spicule structures. The simulated masses were embedded within actual digitized mammograms. The authors evaluated the realism of the resulting hybrid phantoms by generating corresponding left- and right-breast image pairs, consisting of one breast image containing a real mass, and the opposite breast image of the same patient containing a similar simulated mass. The authors then used computer-aided diagnosis (CAD) methods and expert radiologist readers to determine whether significant differences can be observed between the real and hybrid images. Results: The authors found no statistically significant difference between the CAD features obtained from the real and simulated images of masses with either spiculated or nonspiculated margins. Likewise, the authors found that expert human readers performed very poorly in discriminating their hybrid images from real mammograms. Conclusions: The authors’ proposed method permits the realistic simulation of 3D breast masses having user-defined characteristics, enabling the creation of a large set of hybrid breast images containing a well-characterized mass, embedded within real breast background. The computational nature of the model makes it suitable for detectability studies, evaluation of computer aided diagnosis algorithms, and
A computational model to generate simulated three-dimensional breast masses
Sisternes, Luis de; Brankov, Jovan G.; Zysk, Adam M.; Wernick, Miles N.; Schmidt, Robert A.; Nishikawa, Robert M.
2015-02-15
Purpose: To develop algorithms for creating realistic three-dimensional (3D) simulated breast masses and embedding them within actual clinical mammograms. The proposed techniques yield high-resolution simulated breast masses having randomized shapes, with user-defined mass type, size, location, and shape characteristics. Methods: The authors describe a method of producing 3D digital simulations of breast masses and a technique for embedding these simulated masses within actual digitized mammograms. Simulated 3D breast masses were generated by using a modified stochastic Gaussian random sphere model to generate a central tumor mass, and an iterative fractal branching algorithm to add complex spicule structures. The simulated masses were embedded within actual digitized mammograms. The authors evaluated the realism of the resulting hybrid phantoms by generating corresponding left- and right-breast image pairs, consisting of one breast image containing a real mass, and the opposite breast image of the same patient containing a similar simulated mass. The authors then used computer-aided diagnosis (CAD) methods and expert radiologist readers to determine whether significant differences can be observed between the real and hybrid images. Results: The authors found no statistically significant difference between the CAD features obtained from the real and simulated images of masses with either spiculated or nonspiculated margins. Likewise, the authors found that expert human readers performed very poorly in discriminating their hybrid images from real mammograms. Conclusions: The authors’ proposed method permits the realistic simulation of 3D breast masses having user-defined characteristics, enabling the creation of a large set of hybrid breast images containing a well-characterized mass, embedded within real breast background. The computational nature of the model makes it suitable for detectability studies, evaluation of computer aided diagnosis algorithms, and
Jeong, Ji-wook; Chae, Seung-Hoon; Chae, Eun Young; Kim, Hak Hee; Choi, Young-Wook; Lee, Sooyeul
2016-01-01
We propose computer-aided detection (CADe) algorithm for microcalcification (MC) clusters in reconstructed digital breast tomosynthesis (DBT) images. The algorithm consists of prescreening, MC detection, clustering, and false-positive (FP) reduction steps. The DBT images containing the MC-like objects were enhanced by a multiscale Hessian-based three-dimensional (3D) objectness response function and a connected-component segmentation method was applied to extract the cluster seed objects as potential clustering centers of MCs. Secondly, a signal-to-noise ratio (SNR) enhanced image was also generated to detect the individual MC candidates and prescreen the MC-like objects. Each cluster seed candidate was prescreened by counting neighboring individual MC candidates nearby the cluster seed object according to several microcalcification clustering criteria. As a second step, we introduced bounding boxes for the accepted seed candidate, clustered all the overlapping cubes, and examined. After the FP reduction step, the average number of FPs per case was estimated to be 2.47 per DBT volume with a sensitivity of 83.3%. PMID:27274993
NASA Astrophysics Data System (ADS)
Müller, Ert; Riedel, Marco; Thurner, Philipp J.
2006-04-01
Micro-computed tomography with the highly intense, monochromatic X rays produced by the synchrotron is a superior method to nondestructively measure the local absorption in three-dimensional space. Because biological tissues and cells consist mainly of water as the surrounding medium, higher absorbing agents have to be incorporated into the structures of interest. Even without X-ray optics such as refractive lens, one can uncover the stain distribution with the spatial resolution of about 1 [mu]m. Incorporating the stain at selected cell compartments, for example, binding to the RNA/DNA, their density distribution becomes quantified. In this communication, we demonstrate that tomograms obtained at the beamlines BW2 and W2 (HASYLAB at DESY, Hamburg, Germany) and 4S (SLS, Villigen, Switzerland) clearly show that the RNA/DNA-stained HEK 293 cell clusters have a core of high density and a peripheral part of lower density, which correlate with results of optical microscopy. The inner part of the clusters is associated with nonvital cells as the result of insufficient oxygen and nutrition supply. This necrotic part is surrounded by (6 ± 1) layers of vital cells.
Anthropometry of the Human Scaphoid Waist by Three-Dimensional Computed Tomography.
Smith, Jennifer; Hofmeister, Eric P; Renninger, Christopher; Kroonen, Leo T
2015-01-01
Published measurements for the scaphoid are scarce. The purpose of this study is to define anthropometric norms for the waist of the scaphoid to assist in optimizing bone graft quantity and implant use. Computed tomography images of the wrist were reviewed by three surgeons. Anthropometric data were gathered, including the scaphoid waist diameter in two dimensions and the scaphoid waist volume. Each study was measured twice, allowing for determination of inter- and intraobserver reliability. Forty-three studies were examined (23 female and 20 male). Average measurements of the scaphoid waist were 11.28 ± 0.26 mm in the sagittal plane and 8.70 ± 0.17 mm in the coronal plane, and the waist volume was 715 ± 33.0 mm3. Specific measures of the narrowest portion of the scaphoid are provided by this study. Measurements of the scaphoid waist through the use of three-dimensional imaging are an accurate method with good inter- and intraobserver reliability. The measurements obtained from this study can be applied to guide graft and implant selection for treatment of scaphoid waist fractures and nonunions. PMID:26688990
Bergemann, Claudia; Elter, Patrick; Lange, Regina; Weißmann, Volker; Hansmann, Harald; Klinkenberg, Ernst-Dieter; Nebe, Barbara
2015-01-01
Studies on bone cell ingrowth into synthetic, porous three-dimensional (3D) implants showed difficulties arising from impaired cellular proliferation and differentiation in the core region of these scaffolds with increasing scaffold volume in vitro. Therefore, we developed an in vitro perfusion cell culture module, which allows the analysis of cells in the interior of scaffolds under different medium flow rates. For each flow rate the cell viability was measured and compared with results from computer simulations that predict the local oxygen supply and shear stress inside the scaffold based on the finite element method. We found that the local cell viability correlates with the local oxygen concentration and the local shear stress. On the one hand the oxygen supply of the cells in the core becomes optimal with a higher perfusion flow. On the other hand shear stress caused by high flow rates impedes cell vitality, especially at the surface of the scaffold. Our results demonstrate that both parameters must be considered to derive an optimal nutrient flow rate. PMID:26539216
Jeong, Ji-Wook; Chae, Seung-Hoon; Chae, Eun Young; Kim, Hak Hee; Choi, Young-Wook; Lee, Sooyeul
2016-01-01
We propose computer-aided detection (CADe) algorithm for microcalcification (MC) clusters in reconstructed digital breast tomosynthesis (DBT) images. The algorithm consists of prescreening, MC detection, clustering, and false-positive (FP) reduction steps. The DBT images containing the MC-like objects were enhanced by a multiscale Hessian-based three-dimensional (3D) objectness response function and a connected-component segmentation method was applied to extract the cluster seed objects as potential clustering centers of MCs. Secondly, a signal-to-noise ratio (SNR) enhanced image was also generated to detect the individual MC candidates and prescreen the MC-like objects. Each cluster seed candidate was prescreened by counting neighboring individual MC candidates nearby the cluster seed object according to several microcalcification clustering criteria. As a second step, we introduced bounding boxes for the accepted seed candidate, clustered all the overlapping cubes, and examined. After the FP reduction step, the average number of FPs per case was estimated to be 2.47 per DBT volume with a sensitivity of 83.3%. PMID:27274993
Wendel, M.W.; Siman-Tov, M.
1998-11-01
The Spallation Neutron Source (SNS) is a high-power accelerator-based pulsed spallation source being designed by a multilaboratory team led by Oak Ridge National Laboratory (ORNL) to achieve high fluxes of neutrons for scientific experiments. Computational fluid dynamics (CFD) is being used to analyze the SNS design. The liquid-mercury target is subjected to the neutronic (internal) heat generation that results from the proton collisions with the mercury nuclei. The liquid mercury simultaneously serves as the neutronic target medium, transports away the heat generated within itself, and cools the metallic target structure. Recirculation and stagnation zones within the target are of particular concern because of the likelihood that they will result in local hot spots. These zones exist because the most feasible target designs include a complete U-turn flow redirection. Although the primary concern is that the target is adequately cooled, the pressure drop from inlet to outlet must also be considered because pressure drop directly affects structural loading and required pumping power. Based on the current design, a three-dimensional CFD model has been developed that includes the stainless steel target structure, the liquid-mercury target flow, and the liquid-mercury cooling jacket that wraps around the nose of the target.
Three-dimensional visualisation of soft biological structures by X-ray computed micro-tomography.
Shearer, Tom; Bradley, Robert S; Hidalgo-Bastida, L Araida; Sherratt, Michael J; Cartmell, Sarah H
2016-07-01
Whereas the two-dimensional (2D) visualisation of biological samples is routine, three-dimensional (3D) imaging remains a time-consuming and relatively specialised pursuit. Current commonly adopted techniques for characterising the 3D structure of non-calcified tissues and biomaterials include optical and electron microscopy of serial sections and sectioned block faces, and the visualisation of intact samples by confocal microscopy or electron tomography. As an alternative to these approaches, X-ray computed micro-tomography (microCT) can both rapidly image the internal 3D structure of macroscopic volumes at sub-micron resolutions and visualise dynamic changes in living tissues at a microsecond scale. In this Commentary, we discuss the history and current capabilities of microCT. To that end, we present four case studies to illustrate the ability of microCT to visualise and quantify: (1) pressure-induced changes in the internal structure of unstained rat arteries, (2) the differential morphology of stained collagen fascicles in tendon and ligament, (3) the development of Vanessa cardui chrysalises, and (4) the distribution of cells within a tissue-engineering construct. Future developments in detector design and the use of synchrotron X-ray sources might enable real-time 3D imaging of dynamically remodelling biological samples. PMID:27278017
Pandolfi, Anna; Holzapfel, Gerhard A
2008-12-01
Experimental tests on human corneas reveal distinguished reinforcing collagen lamellar structures that may be well described by a structural constitutive model considering distributed collagen fibril orientations along the superior-inferior and the nasal-temporal meridians. A proper interplay between the material structure and the geometry guarantees the refractive function and defines the refractive properties of the cornea. We propose a three-dimensional computational model for the human cornea that is able to provide the refractive power by analyzing the structural mechanical response with the nonlinear regime and the effect the intraocular pressure has. For an assigned unloaded geometry we show how the distribution of the von Mises stress at the top surface of the cornea and through the corneal thickness and the refractive power depend on the material properties and the fibril dispersion. We conclude that a model for the human cornea must not disregard the peculiar collagen fibrillar structure, which equips the cornea with the unique biophysical, mechanical, and optical properties. PMID:19045535
Mısırlıoglu, Melda; Nalcaci, Rana; Yardımcı, Selmi
2013-01-01
Purpose Tonsilloliths are calcifications found in the crypts of the palatal tonsils and can be detected on routine panoramic examinations. This study was performed to highlight the benefits of cone-beam computed tomography (CBCT) in the diagnosis of tonsilloliths appearing bilaterally on panoramic radiographs. Materials and Methods The sample group consisted of 7 patients who had bilateral radiopaque lesions at the area of the ascending ramus on panoramic radiographs. CBCT images for every patient were obtained from both sides of the jaw to determine the exact locations of the lesions and to rule out other calcifications. The calcifications were evaluated on the CBCT images using Ez3D2009 software. Additionally, the obtained images in DICOM format were transferred to ITK SNAP 2.4.0 pc software for semiautomatic segmentation. Segmentation was performed using contrast differences between the soft tissues and calcifications on grayscale images, and the volume in mm3 of the segmented three dimensional models were obtained. Results CBCT scans revealed that what appeared on panoramic radiographs as bilateral images were in fact unilateral lesions in 2 cases. The total volume of the calcifications ranged from 7.92 to 302.5mm3. The patients with bilaterally multiple and large calcifications were found to be symptomatic. Conclusion The cases provided the evidence that tonsilloliths should be considered in the differential diagnosis of radiopaque masses involving the mandibular ramus, and they highlight the need for a CBCT scan to differentiate pseudo- or ghost images from true bilateral pathologies. PMID:24083209
Teslow, T.N.
1985-01-01
Using computed tomogram time series, myocardial perfusion was angiographically measured as distributions of x-ray circulatory indicators in three dimensions. By separating the dynamic function from the cardiac structure, these separate components were tested using region-of-interest (ROI) mensuration in simulation, phantom, and in vivo experiments. Statistical criteria were used to evaluate the dynamic component which was represented by analytic mathematical models of indicator dilution. The spatial component was represented by three-dimensional (3-D) and two-dimensional (2-D) geometric models of the heart. Each of these components were determined in individual ROI's and globally integrated to manifest the perfusion heterogeneities. A physical heart phantom with controllable regional perfusion characteristics was also developed and studied. Experiments conducted on dogs compared the accuracy of 2-D and 3-D perfusion measurements by imaging to those using gamma-radioactive microspheres. Accurate reproducible localization of the heart was found to be important for obtaining accurate measures of regional perfusion in 3-D volume images exhibiting high noise.
NASA Astrophysics Data System (ADS)
Tsivilskiy, I. V.; Nagulin, K. Yu.; Gilmutdinov, A. Kh.
2016-02-01
A full three-dimensional nonstationary numerical model of graphite electrothermal atomizers of various types is developed. The model is based on solution of a heat equation within solid walls of the atomizer with a radiative heat transfer and numerical solution of a full set of Navier-Stokes equations with an energy equation for a gas. Governing equations for the behavior of a discrete phase, i.e., atomic particles suspended in a gas (including gas-phase processes of evaporation and condensation), are derived from the formal equations molecular kinetics by numerical solution of the Hertz-Langmuir equation. The following atomizers test the model: a Varian standard heated electrothermal vaporizer (ETV), a Perkin Elmer standard THGA transversely heated graphite tube with integrated platform (THGA), and the original double-stage tube-helix atomizer (DSTHA). The experimental verification of computer calculations is carried out by a method of shadow spectral visualization of the spatial distributions of atomic and molecular vapors in an analytical space of an atomizer.
Three-dimensional analysis of root canal geometry by high-resolution computed tomography.
Peters, O A; Laib, A; Rüegsegger, P; Barbakow, F
2000-06-01
A detailed understanding of the complexity of root canal systems is imperative to ensure successful root canal preparation. The aim of this study was to evaluate the potential and accuracy of a three-dimensional, non-destructive technique for detailing root canal geometry by means of high-resolution tomography. The anatomy of root canals in 12 extracted human maxillary molars was analyzed by means of a micro-computed tomography scanner (microCT, cubic resolution 34 microm). A special mounting device facilitated repeated precise repositioning of the teeth in the microCT. Surface areas and volumes of each canal were calculated by triangulation, and means were determined. Model-independent methods were used to evaluate the canals' diameters and configuration. The calculated and measured volumes and the areas of artificial root canals, produced by the drilling of precision holes into dentin disks, were well-correlated. Semi-automated repositioning of specimens resulted in near-perfect matching (< 1 voxel) when outer canal contours were assessed. Root canal geometry was accurately assessed by this innovative technique; therefore, variables and indices presented may serve as a basis for further analyses of root canal anatomy in experimental endodontology. PMID:10890720
Koerich, L; Burns, D; Weissheimer, A; Claus, J D P
2016-05-01
This study aimed to validate a novel method for fast regional superimposition of cone beam computed tomography (CBCT) scans. The method can be used with smaller field of view scans, thereby allowing for a lower radiation dose. This retrospective study used two dry skulls and secondary data from 15 patients who had more than one scan taken using the same machine. Two observers tested two types of regional voxel-based superimposition: maxillary and mandibular. The registration took 10-15s. Three-dimensional surface models of the maxillas and mandibles were generated via standardized threshold segmentation, and the accuracy and reproducibility of the superimpositions were assessed using the iterative closest point technique to measure the root mean square (RMS) distance between the images. Five areas were measured and a RMS≤0.25 was considered successful. Descriptive statistics and the intra-class correlation coefficient (ICC) were used to compare the intra-observer measurement reproducibility. The ICC was ≥0.980 for all of the variables and the highest RMS found was 0.241. The inter-observer reproducibility was assessed case by case and was perfect (RMS 0) for 68% (23 out of 34) of the superimpositions done and not clinically significant (RMS≤0.25) for the other 32%. The method is fast, accurate, and reproducible and is an alternative to cranial base superimposition. PMID:26794399
Affective three-dimensional brain-computer interface created using a prism array-based display
NASA Astrophysics Data System (ADS)
Mun, Sungchul; Park, Min-Chul
2014-12-01
To avoid the vergence-accommodation mismatch and provide a strong sense of presence to users, we applied a prism array-based display when presenting three-dimensional (3-D) objects. Emotional pictures were used as visual stimuli to increase the signal-to-noise ratios of steady-state visually evoked potentials (SSVEPs) because involuntarily motivated selective attention by affective mechanisms can enhance SSVEP amplitudes, thus producing increased interaction efficiency. Ten male and nine female participants voluntarily participated in our experiments. Participants were asked to control objects under three viewing conditions: two-dimension (2-D), stereoscopic 3-D, and prism. The participants performed each condition in a counter-balanced order. One-way repeated measures analysis of variance showed significant increases in the positive predictive values in the prism condition compared to the 2-D and 3-D conditions. Participants' subjective ratings of realness and engagement were also significantly greater in the prism condition than in the 2-D and 3-D conditions, while the ratings for visual fatigue were significantly reduced in the prism condition than in the 3-D condition. The proposed methods are expected to enhance the sense of reality in 3-D space without causing critical visual fatigue. In addition, people who are especially susceptible to stereoscopic 3-D may be able to use the affective brain-computer interface.
Wery, M F; Nada, R M; van der Meulen, J J; Wolvius, E B; Ongkosuwito, E M
2015-03-01
There is little anteroposterior growth of the midface in patients with syndromic craniosynostosis who are followed up over time without intervention. A Le Fort III with distraction osteogenesis can be done to correct this. This is a controlled way in which to achieve appreciable stable advancement of the midface without the need for bone grafting, but the vector of the movement is not always predictable. The purpose of this study was to evaluate the 3-dimensional effect of Le Fort III distraction osteogenesis with an external frame. Ten patients (aged 7-19 years) who had the procedure were included in the study. The le Fort III procedure and the placement of the external frame were followed by an activation period and then a 3-month retention period. Computed tomographic (CT) images taken before and after operation were converted and loaded into 3-dimensional image rendering software and compared with the aid of a paired sample t test and a colour-coded qualitative analysis. Comparison of the CT data before and after distraction indicated that the amount of midface advancement was significant. Le Fort III distraction osteogenesis is an effective way to advance the midface. However, the movement during osteogenesis is not always exactly in the intended direction, and a secondary operation is often necessary. Three-dimensional evaluation over a longer period of time is necessary. PMID:25605236
Self-organized Au nanoarrays on vertical graphenes: an advanced three-dimensional sensing platform.
Rider, Amanda Evelyn; Kumar, Shailesh; Furman, Scott A; Ostrikov, Kostya Ken
2012-03-11
A three-dimensional surface enhanced Raman scattering (SERS)/plasmonic sensing platform based on plasma-enabled, catalyst-free, few-layer vertical graphenes decorated with self-organized Au nanoparticle arrays is demonstrated. This platform is viable for multiple species detection and overcomes several limitations of two-dimensional sensors. PMID:22227575
NASA Technical Reports Server (NTRS)
Chima, R. V.; Strazisar, A. J.
1982-01-01
Two and three dimensional inviscid solutions for the flow in a transonic axial compressor rotor at design speed are compared with probe and laser anemometers measurements at near-stall and maximum-flow operating points. Experimental details of the laser anemometer system and computational details of the two dimensional axisymmetric code and three dimensional Euler code are described. Comparisons are made between relative Mach number and flow angle contours, shock location, and shock strength. A procedure for using an efficient axisymmetric code to generate downstream pressure input for computationally expensive Euler codes is discussed. A film supplement shows the calculations of the two operating points with the time-marching Euler code.
Trent, D.S.; Eyler, L.L.; Budden, M.J.
1983-09-01
This document describes the numerical methods, current capabilities, and the use of the TEMPEST (Version L, MOD 2) computer program. TEMPEST is a transient, three-dimensional, hydrothermal computer program that is designed to analyze a broad range of coupled fluid dynamic and heat transfer systems of particular interest to the Fast Breeder Reactor thermal-hydraulic design community. The full three-dimensional, time-dependent equations of motion, continuity, and heat transport are solved for either laminar or turbulent fluid flow, including heat diffusion and generation in both solid and liquid materials. 10 refs., 22 figs., 2 tabs.
NASA Astrophysics Data System (ADS)
Biotteau, E.; Gravouil, A.; Lubrecht, A. A.; Combescure, A.
2012-01-01
In this paper, the refinement strategy based on the "Non-Linear Localized Full MultiGrid" solver originally published in Int. J. Numer. Meth. Engng 84(8):947-971 (2010) for 2-D structural problems is extended to 3-D simulations. In this context, some extra information concerning the refinement strategy and the behavior of the error indicators are given. The adaptive strategy is dedicated to the accurate modeling of elastoplastic materials with isotropic hardening in transient dynamics. A multigrid solver with local mesh refinement is used to reduce the amount of computational work needed to achieve an accurate calculation at each time step. The locally refined grids are automatically constructed, depending on the user prescribed accuracy. The discretization error is estimated by a dedicated error indicator within the multigrid method. In contrast to other adaptive procedures, where grids are erased when new ones are generated, the previous solutions are used recursively to reduce the computing time on the new mesh. Moreover, the adaptive strategy needs no costly coarsening method as the mesh is reassessed at each time step. The multigrid strategy improves the convergence rate of the non-linear solver while ensuring the information transfer between the different meshes. It accounts for the influence of localized non-linearities on the whole structure. All the steps needed to achieve the adaptive strategy are automatically performed within the solver such that the calculation does not depend on user experience. This paper presents three-dimensional results using the adaptive multigrid strategy on elastoplastic structures in transient dynamics and in a linear geometrical framework. Isoparametric cubic elements with energy and plastic work error indicators are used during the calculation.
Henshaw, W; Schwendeman, D
2007-11-15
This paper describes an approach for the numerical solution of time-dependent partial differential equations in complex three-dimensional domains. The domains are represented by overlapping structured grids, and block-structured adaptive mesh refinement (AMR) is employed to locally increase the grid resolution. In addition, the numerical method is implemented on parallel distributed-memory computers using a domain-decomposition approach. The implementation is flexible so that each base grid within the overlapping grid structure and its associated refinement grids can be independently partitioned over a chosen set of processors. A modified bin-packing algorithm is used to specify the partition for each grid so that the computational work is evenly distributed amongst the processors. All components of the AMR algorithm such as error estimation, regridding, and interpolation are performed in parallel. The parallel time-stepping algorithm is illustrated for initial-boundary-value problems involving a linear advection-diffusion equation and the (nonlinear) reactive Euler equations. Numerical results are presented for both equations to demonstrate the accuracy and correctness of the parallel approach. Exact solutions of the advection-diffusion equation are constructed, and these are used to check the corresponding numerical solutions for a variety of tests involving different overlapping grids, different numbers of refinement levels and refinement ratios, and different numbers of processors. The problem of planar shock diffraction by a sphere is considered as an illustration of the numerical approach for the Euler equations, and a problem involving the initiation of a detonation from a hot spot in a T-shaped pipe is considered to demonstrate the numerical approach for the reactive case. For both problems, the solutions are shown to be well resolved on the finest grid. The parallel performance of the approach is examined in detail for the shock diffraction problem.
NASA Astrophysics Data System (ADS)
Song, Huimin
In the aerospace and automotive industries, many finite element analyses use lower-dimensional finite elements such as beams, plates and shells, to simplify the modeling. These simplified models can greatly reduce the computation time and cost; however, reduced-dimensional models may introduce inaccuracies, particularly near boundaries and near portions of the structure where reduced-dimensional models may not apply. Another factor in creation of such models is that beam-like structures frequently have complex geometry, boundaries and loading conditions, which may make them unsuitable for modeling with single type of element. The goal of this dissertation is to develop a method that can accurately and efficiently capture the response of a structure by rigorous combination of a reduced-dimensional beam finite element model with a model based on full two-dimensional (2D) or three-dimensional (3D) finite elements. The first chapter of the thesis gives the background of the present work and some related previous work. The second chapter is focused on formulating a system of equations that govern the joining of a 2D model with a beam model for planar deformation. The essential aspect of this formulation is to find the transformation matrices to achieve deflection and load continuity on the interface. Three approaches are provided to obtain the transformation matrices. An example based on joining a beam to a 2D finite element model is examined, and the accuracy of the analysis is studied by comparing joint results with the full 2D analysis. The third chapter is focused on formulating the system of equations for joining a beam to a 3D finite element model for static and free-vibration problems. The transition between the 3D elements and beam elements is achieved by use of the stress recovery technique of the variational-asymptotic method as implemented in VABS (the Variational Asymptotic Beam Section analysis). The formulations for an interface transformation matrix and
NASA Technical Reports Server (NTRS)
Logan, Terry G.
1994-01-01
The purpose of this study is to investigate the performance of the integral equation computations using numerical source field-panel method in a massively parallel processing (MPP) environment. A comparative study of computational performance of the MPP CM-5 computer and conventional Cray-YMP supercomputer for a three-dimensional flow problem is made. A serial FORTRAN code is converted into a parallel CM-FORTRAN code. Some performance results are obtained on CM-5 with 32, 62, 128 nodes along with those on Cray-YMP with a single processor. The comparison of the performance indicates that the parallel CM-FORTRAN code near or out-performs the equivalent serial FORTRAN code for some cases.
High-immersion three-dimensional display of the numerical computer model
NASA Astrophysics Data System (ADS)
Xing, Shujun; Yu, Xunbo; Zhao, Tianqi; Cai, Yuanfa; Chen, Duo; Chen, Zhidong; Sang, Xinzhu
2013-08-01
High-immersion three-dimensional (3D) displays making them valuable tools for many applications, such as designing and constructing desired building houses, industrial architecture design, aeronautics, scientific research, entertainment, media advertisement, military areas and so on. However, most technologies provide 3D display in the front of screens which are in parallel with the walls, and the sense of immersion is decreased. To get the right multi-view stereo ground image, cameras' photosensitive surface should be parallax to the public focus plane and the cameras' optical axes should be offset to the center of public focus plane both atvertical direction and horizontal direction. It is very common to use virtual cameras, which is an ideal pinhole camera to display 3D model in computer system. We can use virtual cameras to simulate the shooting method of multi-view ground based stereo image. Here, two virtual shooting methods for ground based high-immersion 3D display are presented. The position of virtual camera is determined by the people's eye position in the real world. When the observer stand in the circumcircle of 3D ground display, offset perspective projection virtual cameras is used. If the observer stands out the circumcircle of 3D ground display, offset perspective projection virtual cameras and the orthogonal projection virtual cameras are adopted. In this paper, we mainly discussed the parameter setting of virtual cameras. The Near Clip Plane parameter setting is the main point in the first method, while the rotation angle of virtual cameras is the main point in the second method. In order to validate the results, we use the D3D and OpenGL to render scenes of different viewpoints and generate a stereoscopic image. A realistic visualization system for 3D models is constructed and demonstrated for viewing horizontally, which provides high-immersion 3D visualization. The displayed 3D scenes are compared with the real objects in the real world.
Kim, Jung-Jae; Jung, Chul-Young; Eastman, Jonathan G.
2016-01-01
Background Percutaneous iliosacral screw fixation can provide stable fixation with a minimally invasive surgical technique for unstable posterior pelvic ring injuries. This surgical technique is not limited by cases of difficult fracture patterns, sacral dysplasia, and small sacral pedicles that can occur in Asians. The purpose of this study was to investigate the incidence of the sacral dysplasia in the Korean population and determine the optimal direction of iliosacral screws by analyzing pelvic three-dimensional computed tomography (3D-CT) scans. Methods One hundred adult patients who had pelvic 3D-CT scans were evaluated. The upper sacral morphology was classified into three groups, i.e., normal, transitional, and dysplastic groups; the cross-sectional area of the safe zone was measured in each group. S1 pedicle with a short width of more than 11 mm was defined as safe pedicle. The incidences of safe pedicles at different angles ranging from 0° to 15° were investigated in order to determine optimal angle for screw direction. Results The incidence of normal, transitional, and dysplastic group was 46%, 32%, and 22%, respectively. There were significant increases of the cross-sectional area of the safe zones by increasing the angles from 0° to 15° in all groups. The incidence of safe pedicles increased similar to the changes in cross-sectional area. The overall incidence of safe pedicles was highest at the 10° tilt angle. Conclusions The incidence of sacral dysplasia in Koreans was 54%, which is higher than previous studies for Western populations. The cross-sectional area of the safe zone can be increased by anteromedial direction of the iliosacral screw. Considering the diversity of sacral morphology present in the Korean population, a tilt angle of 10° may be the safest angle. PMID:27247736
Development of a percentile based three-dimensional model of the buttocks in computer system
NASA Astrophysics Data System (ADS)
Wang, Lijing; He, Xueli; Li, Hongpeng
2016-04-01
There are diverse products related to human buttocks, which need to be designed, manufactured and evaluated with 3D buttock model. The 3D buttock model used in present research field is just simple approximate model similar to human buttocks. The 3D buttock percentile model is highly desired in the ergonomics design and evaluation for these products. So far, there is no research on the percentile sizing system of human 3D buttock model. So the purpose of this paper is to develop a new method for building three-dimensional buttock percentile model in computer system. After scanning the 3D shape of buttocks, the cloud data of 3D points is imported into the reverse engineering software (Geomagic) for the reconstructing of the buttock surface model. Five characteristic dimensions of the buttock are measured through mark-points after models being imported into engineering software CATIA. A series of space points are obtained by the intersecting of the cutting slices and 3D buttock surface model, and then are ordered based on the sequence number of the horizontal and vertical slices. The 1st, 5th, 50th, 95th, 99th percentile values of the five dimensions and the spatial coordinate values of the space points are obtained, and used to reconstruct percentile buttock models. This research proposes a establishing method of percentile sizing system of buttock 3D model based on the percentile values of the ischial tuberosities diameter, the distances from margin to ischial tuberosity and the space coordinates value of coordinate points, for establishing the Nth percentile 3D buttock model and every special buttock types model. The proposed method also serves as a useful guidance for the other 3D percentile models establishment for other part in human body with characteristic points.
Three-Dimensional Acoustic Tissue Model: A Computational Tissue Phantom for Image Analyses
NASA Astrophysics Data System (ADS)
Mamou, J.; Oelze, M. L.; O'Brien, W. D.; Zachary, J. F.
A novel methodology to obtain three-dimensional (3D) acoustic tissue models (3DATMs) is introduced. 3DATMs can be used as computational tools for ultrasonic imaging algorithm development and analysis. In particular, 3D models of biological structures can provide great benefit to better understand fundamentally how ultrasonic waves interact with biological materials. As an example, such models were used to generate ultrasonic images that characterize tumor tissue microstructures. 3DATMs can be used to evaluate a variety of tissue types. Typically, excised tissue is fixed, embedded, serially sectioned, and stained. The stained sections are digitally imaged (24-bit bitmap) with light microscopy. Contrast of each stained section is equalized and an automated registration algorithm aligns consecutive sections. The normalized mutual information is used as a similarity measure, and simplex optimization is conducted to find the best alignment. Both rigid and non-rigid registrations are performed. During tissue preparation, some sections are generally lost; thus, interpolation prior to 3D reconstruction is performed. Interpolation is conducted after registration using cubic Hermite polynoms. The registered (with interpolated) sections yield a 3D histologic volume (3DHV). Acoustic properties are then assigned to each tissue constituent of the 3DHV to obtain the 3DATMs. As an example, a 3D acoustic impedance tissue model (3DZM) was obtained for a solid breast tumor (EHS mouse sarcoma) and used to estimate ultrasonic scatterer size. The 3DZM results yielded an effective scatterer size of 32.9 (±6.1) μm. Ultrasonic backscatter measurements conducted on the same tumor tissue in vivo yielded an effective scatterer size of 33 (±8) μm. This good agreement shows that 3DATMs may be a powerful modeling tool for acoustic imaging applications
Scott, Anna E.; Vasilescu, Dragos M.; Seal, Katherine A. D.; Keyes, Samuel D.; Mavrogordato, Mark N.; Hogg, James C.; Sinclair, Ian; Warner, Jane A.; Hackett, Tillie-Louise; Lackie, Peter M.
2015-01-01
Background Understanding the three-dimensional (3-D) micro-architecture of lung tissue can provide insights into the pathology of lung disease. Micro computed tomography (µCT) has previously been used to elucidate lung 3D histology and morphometry in fixed samples that have been stained with contrast agents or air inflated and dried. However, non-destructive microstructural 3D imaging of formalin-fixed paraffin embedded (FFPE) tissues would facilitate retrospective analysis of extensive tissue archives of lung FFPE lung samples with linked clinical data. Methods FFPE human lung tissue samples (n = 4) were scanned using a Nikon metrology µCT scanner. Semi-automatic techniques were used to segment the 3D structure of airways and blood vessels. Airspace size (mean linear intercept, Lm) was measured on µCT images and on matched histological sections from the same FFPE samples imaged by light microscopy to validate µCT imaging. Results The µCT imaging protocol provided contrast between tissue and paraffin in FFPE samples (15mm x 7mm). Resolution (voxel size 6.7 µm) in the reconstructed images was sufficient for semi-automatic image segmentation of airways and blood vessels as well as quantitative airspace analysis. The scans were also used to scout for regions of interest, enabling time-efficient preparation of conventional histological sections. The Lm measurements from µCT images were not significantly different to those from matched histological sections. Conclusion We demonstrated how non-destructive imaging of routinely prepared FFPE samples by laboratory µCT can be used to visualize and assess the 3D morphology of the lung including by morphometric analysis. PMID:26030902
Three-dimensional computed tomography in laparoscopic surgery for colorectal carcinoma
Ohtani, Hiroshi; Ohta, Kohei; Arimoto, Yuichi; Kim, Eui-Chul; Oba, Hiroko; Adachi, Kenji; Terakawa, Shoichi; Tsubakimoto, Mitsuo
2005-01-01
AIM: To evaluate the usefulness of three-dimensional computed tomography (3DCT) in laparoscopic surgery for colorectal carcinoma. METHODS: Seventy-two patients with colorectal cancer who underwent curative operation at our hospital were enrolled in this study. They were classified into two groups by operative procedures. Sixteen patients underwent laparoscopic surgery, laparoscopic group (LG), while 56 patients underwent conventional open surgery, open group (OG). At our institution, contrast-enhanced CT is routinely performed as part of intra-abdominal screening and the 3D images of the major regional vessels are described. We have previously described about the preoperative visualization of the inferior mesenteric artery (IMA) by 3DCT. This time we newly acquired 3D images of the superior mesenteric artery (SMA)/superior mesenteric vein (SMV), ileocecal artery (ICA), middle colic artery (MCA), and inferior mesenteric vein (IMV). We have compared our two study groups with regard to five items, including clinical anastomotic leakage. We have discussed here the role of 3DCT in laparoscopic surgery for colorectal carcinoma. RESULTS: The mean length of the incision in LG was 4.625±0.89 cm, which was significantly shorter than that in OG (P<0.001). The association between ICA and SMV and SMA was described in the right-sided colectomy. The preoperative imaging of IMA and IMV was created in the rectosigmoidectomy. There was no significant difference in anastomotic leakage between the two groups, but no patients in LG experienced anastomotic leakage. CONCLUSION: Most of the patients are satisfied with the shorter incisional length following laparoscopic surgery. Preoperative visualization of the major regional vessels may be helpful for the secure treatment of the anastomosis in laparoscopic surgery for colorectal carcinoma. PMID:16437595
Development of a percentile based three-dimensional model of the buttocks in computer system
NASA Astrophysics Data System (ADS)
Wang, Lijing; He, Xueli; Li, Hongpeng
2016-05-01
There are diverse products related to human buttocks, which need to be designed, manufactured and evaluated with 3D buttock model. The 3D buttock model used in present research field is just simple approximate model similar to human buttocks. The 3D buttock percentile model is highly desired in the ergonomics design and evaluation for these products. So far, there is no research on the percentile sizing system of human 3D buttock model. So the purpose of this paper is to develop a new method for building three-dimensional buttock percentile model in computer system. After scanning the 3D shape of buttocks, the cloud data of 3D points is imported into the reverse engineering software (Geomagic) for the reconstructing of the buttock surface model. Five characteristic dimensions of the buttock are measured through mark-points after models being imported into engineering software CATIA. A series of space points are obtained by the intersecting of the cutting slices and 3D buttock surface model, and then are ordered based on the sequence number of the horizontal and vertical slices. The 1st, 5th, 50th, 95th, 99th percentile values of the five dimensions and the spatial coordinate values of the space points are obtained, and used to reconstruct percentile buttock models. This research proposes a establishing method of percentile sizing system of buttock 3D model based on the percentile values of the ischial tuberosities diameter, the distances from margin to ischial tuberosity and the space coordinates value of coordinate points, for establishing the Nth percentile 3D buttock model and every special buttock types model. The proposed method also serves as a useful guidance for the other 3D percentile models establishment for other part in human body with characteristic points.
NASA Astrophysics Data System (ADS)
Shen, Yi; Diplas, Panayiotis
2008-01-01
SummaryComplex flow patterns generated by irregular channel topography, such as boulders, submerged large woody debris, riprap and spur dikes, provide unique habitat for many aquatic organisms. Numerical modeling of the flow structures surrounding these obstructions is challenging, yet it represents an important tool for aquatic habitat assessment. In this study, the ability of two- (2-D) and three-dimensional (3-D) computational fluid dynamics models to reproduce these localized complex flow features is examined. The 3-D model is validated with laboratory data obtained from the literature for the case of a flow around a hemisphere under emergent and submerged conditions. The performance of the 2-D and 3-D models is then evaluated by comparing the numerical results with field measurements of flow around several boulders located at a reach of the Smith River, a regulated mountainous stream, obtained at base and peak flows. Close agreement between measured values and the velocity profiles predicted by the two models is obtained outside the wakes behind the hemisphere and boulders. However, the results suggest that in the vicinity of these obstructions the 3-D model is better suited for reproducing the circulation flow behavior at both low and high discharges. Application of the 2-D and 3-D models to meso-scale stream flows of ecological significance is furthermore demonstrated by using a recently developed spatial hydraulic metric to quantify flow complexity surrounding a number of brown trout spawning sites. It is concluded that the 3-D model can provide a much more accurate description of the heterogeneous velocity patterns favored by many aquatic species over a broad range of flows, especially under deep flow conditions when the various obstructions are submerged. Issues pertaining to selection of appropriate models for a variety of flow regimes and potential implication of the 3-D model on the development of better habitat suitability criteria are discussed. The
Three-dimensional computational modeling of multiple deformable cells flowing in microvessels
NASA Astrophysics Data System (ADS)
Doddi, Sai K.; Bagchi, Prosenjit
2009-04-01
Three-dimensional (3D) computational modeling and simulation are presented on the motion of a large number of deformable cells in microchannels. The methodology is based on an immersed boundary method, and the cells are modeled as liquid-filled elastic capsules. The model retains two important features of the blood flow in the microcirculation, that is, the particulate nature of blood and deformation of the erythrocytes. The tank-treading and tumbling motion and the lateral migration, as observed for erythrocytes in dilute suspension, are briefly discussed. We then present results on the motion of multiple cells in semidense suspension and study how their collective dynamics leads to various physiologically relevant processes such as the development of the cell-free layer and the Fahraeus-Lindqvist effect. We analyze the 3D trajectory and velocity fluctuations of individual cell in the suspension and the plug-flow velocity profile as functions of the cell deformability, hematocrit, and vessel size. The numerical results allow us to directly obtain various microrheological data, such as the width of the cell-free layer, and the variation in the apparent blood viscosity and hematocrit over the vessel cross section. We then use these results to calculate the core and plasma-layer viscosity and show that the two-phase (or core-annular) model of blood flow in microvessels underpredicts the blood velocity obtained in the simulations by as much as 40%. Based on a posteriori analysis of the simulation data, we develop a three-layer model of blood flow by taking into consideration the smooth variation in viscosity and hematocrit across the interface of the cell-free layer and the core. We then show that the blood velocity predicted by the three-layer model agrees very well with that obtained from the simulations.
Byun, Ha Young; Shin, Heesuk; Lee, Eun Shin; Kong, Min Sik; Lee, Seung Hun
2016-01-01
Objective To assess the intra-rater and inter-rater reliability for measuring femoral anteversion angle (FAA) by a radiographic method using three-dimensional computed tomography reconstruction (3D-CT). Methods The study included 82 children who presented with intoeing gait. 3D-CT data taken between 2006 and 2014 were retrospectively reviewed. FAA was measured by 3D-CT. FAA is defined as the angle between the long axis of the femur neck and condylar axis of the distal femur. FAA measurement was performed twice at both lower extremities by each rater. The intra-rater and inter-rater reliability were calculated by intraclass correlation coefficient (ICC). Results One hundred and sixty-four lower limbs of 82 children (31 boys and 51 girls, 6.3±3.2 years old) were included. The ICCs of intra-rater measurement for the angle of femoral neck axis (NA) were 0.89 for rater A and 0.96 for rater B, and those of condylar axis (CA) were 0.99 for rater A and 0.99 for rater B, respectively. The ICC of inter-rater measurement for the angle of NA was 0.89 and that of CA was 0.92. By each rater, the ICCs of the intrarater measurement for FAA were 0.97 for rater A and 0.95 for rater B, respectively and the ICC of the inter-rater measurement for FAA was 0.89. Conclusion The 3D-CT measures for FAA are reliable within individual raters and between different raters. The 3D-CT measures of FAA can be a useful method for accurate diagnosis and follow-up of femoral anteversion. PMID:27152273
Subgrid or Reynolds stress-modeling for three-dimensional turbulence computations
NASA Technical Reports Server (NTRS)
Rubesin, M. W.
1975-01-01
A review is given of recent advances in two distinct computational methods for evaluating turbulence fields, namely, statistical Reynolds stress modeling and turbulence simulation, where large eddies are followed in time. It is shown that evaluation of the mean Reynolds stresses, rather than use of a scalar eddy viscosity, permits an explanation of streamline curvature effects found in several experiments. Turbulence simulation, with a new volume averaging technique and third-order accurate finite-difference computing is shown to predict the decay of isotropic turbulence in incompressible flow with rather modest computer storage requirements, even at Reynolds numbers of aerodynamic interest.
NASA Technical Reports Server (NTRS)
Anderson, B. H.; Putt, C. W.; Giamati, C. C.
1981-01-01
Color coding techniques used in the processing of remote sensing imagery were adapted and applied to the fluid dynamics problems associated with turbofan mixer nozzles. The computer generated color graphics were found to be useful in reconstructing the measured flow field from low resolution experimental data to give more physical meaning to this information and in scanning and interpreting the large volume of computer generated data from the three dimensional viscous computer code used in the analysis.
NASA Technical Reports Server (NTRS)
Katsanis, T.
1972-01-01
Computer program, CHANEL, can obtain quasi-three-dimensional solutions in any well-guided channel. Conditions that can be handled by program that could not be handled previously are nonuniform inlet temperature, pressure, prewhirl, nonaxial flow where meridional flow angle, meridional stream-line curvature, and radius can vary as desired from hub to tip.
NASA Technical Reports Server (NTRS)
Mcfadden, G. B.; Boisvert, R. F.; Coriell, S. R.
1987-01-01
A finite difference method is used to obtain three-dimensional steady-state solutions for nonplanar interface morphologies in order to study the situation of equal thermal properties in the crystal and melt with negligible latent heat release. Stable steady-state solutions corresponding to two-dimensional bands and three-dimensional hexagonal nodes, as well as to rectangular interface planiforms, are found using a model of an aluminum-chromium alloy with a distribution coefficient of greater than one. Hexagonal nodes are predicted near the onset of instability, in agreement with weakly nonlinear theory.
Three-dimensional computations of cross-flow injection and combustion in a supersonic flow
NASA Technical Reports Server (NTRS)
Carpenter, M. H.
1989-01-01
A low-storage version of the SPARK3D code which is based on the temporally second-order accurate MacCormack (1969) explicit scheme is used to solve the governing equations for three-dimensional chemically reacting flows with finite-rate chemistry. The code includes a fourth-order compact spatial scheme capable of providing higher order spatial accuracy, and it is used to study two-dimensional linear advection, two-dimensional Euler flow, and three-dimensional viscous flow. Also considered are the injection, mixing, and combustion of hydrogen in a supersonic cross stream.
NASA Astrophysics Data System (ADS)
Meng, Jing; Jiang, Zibo; Wang, Lihong V.; Park, Jongin; Kim, Chulhong; Sun, Mingjian; Zhang, Yuanke; Song, Liang
2016-07-01
Photoacoustic computed tomography (PACT) has emerged as a unique and promising technology for multiscale biomedical imaging. To fully realize its potential for various preclinical and clinical applications, development of systems with high imaging speed, reasonable cost, and manageable data flow are needed. Sparse-sampling PACT with advanced reconstruction algorithms, such as compressed-sensing reconstruction, has shown potential as a solution to this challenge. However, most such algorithms require iterative reconstruction and thus intense computation, which may lead to excessively long image reconstruction times. Here, we developed a principal component analysis (PCA)-based PACT (PCA-PACT) that can rapidly reconstruct high-quality, three-dimensional (3-D) PACT images with sparsely sampled data without requiring an iterative process. In vivo images of the vasculature of a human hand were obtained, thus validating the PCA-PACT method. The results showed that, compared with the back-projection (BP) method, PCA-PACT required ˜50% fewer measurements and ˜40% less time for image reconstruction, and the imaging quality was almost the same as that for BP with full sampling. In addition, compared with compressed sensing-based PACT, PCA-PACT had approximately sevenfold faster imaging speed with higher imaging accuracy. This work suggests a promising approach for low-cost, 3-D, rapid PACT for various biomedical applications.
Heller, Stefan
2015-01-01
Single-cell gene expression analysis has contributed to a better understanding of the transcriptional heterogeneity in a variety of model systems, including those used in research in developmental, cancer, and stem cell biology. Nowadays, technological advances facilitate the generation of large gene expression datasets in high-throughput format. Strategies are needed to pertinently visualize this information in a tissue–structure related context, so as to improve data analysis and aid the drawing of meaningful conclusions. Here we describe an approach that utilizes spatial properties of the tissue source to enable the reconstruction of hollow sphere–shaped tissues and organs from single-cell gene expression data in three-dimensional space. To demonstrate our method, we used cells of the mouse otocyst and the renal vesicle as examples. This protocol presents a straightforward computational expression analysis workflow and is implemented on the MATLAB and R statistical computing and graphics software platforms. Hands-on time for typical experiments can be less than 1 h using a standard desktop PC or Mac. PMID:25675210
Maidment, Susannah C R; Bates, Karl T; Falkingham, Peter L; VanBuren, Collin; Arbour, Victoria; Barrett, Paul M
2014-08-01
Ornithischian dinosaurs were primitively bipedal with forelimbs modified for grasping, but quadrupedalism evolved in the clade on at least three occasions independently. Outside of Ornithischia, quadrupedality from bipedal ancestors has only evolved on two other occasions, making this one of the rarest locomotory transitions in tetrapod evolutionary history. The osteological and myological changes associated with these transitions have only recently been documented, and the biomechanical consequences of these changes remain to be examined. Here, we review previous approaches to understanding locomotion in extinct animals, which can be broadly split into form-function approaches using analogy based on extant animals, limb-bone scaling, and computational approaches. We then carry out the first systematic attempt to quantify changes in locomotor muscle function in bipedal and quadrupedal ornithischian dinosaurs. Using three-dimensional computational modelling of the major pelvic locomotor muscle moment arms, we examine similarities and differences among individual taxa, between quadrupedal and bipedal taxa, and among taxa representing the three major ornithischian lineages (Thyreophora, Ornithopoda, Marginocephalia). Our results suggest that the ceratopsid Chasmosaurus and the ornithopod Hypsilophodon have relatively low moment arms for most muscles and most functions, perhaps suggesting poor locomotor performance in these taxa. Quadrupeds have higher abductor moment arms than bipeds, which we suggest is due to the overall wider bodies of the quadrupeds modelled. A peak in extensor moment arms at more extended hip angles and lower medial rotator moment arms in quadrupeds than in bipeds may be due to a more columnar hindlimb and loss of medial rotation as a form of lateral limb support in quadrupeds. We are not able to identify trends in moment arm evolution across Ornithischia as a whole, suggesting that the bipedal ancestry of ornithischians did not constrain the
ERIC Educational Resources Information Center
Finegold, Lawrence S.; And Others
The research and development project demonstrated the viability of a simulated training system to address training issues related to three-dimensional air intercept tactics and geometry, and resulted in the production of two videotapes for use in the United States Air Force Interceptor Weapons School. An introduction discusses the overall…
NASA Technical Reports Server (NTRS)
Yates, Leslie A.
1993-01-01
The construction of interferograms, schlieren, and shadowgraphs from computed flowfield solutions permits one-to-one comparisons of computed and experimental results. A method of constructing these images from both ideal- and real-gas, two and three-dimensional computed flowfields is described. The computational grids can be structured or unstructured, and multiple grids are an option. Constructed images are shown for several types of computed flows including nozzle, wake, and reacting flows; comparisons to experimental images are also shown. In addition, th sensitivity of these images to errors in the flowfield solution is demonstrated, and the constructed images can be used to identify problem areas in the computations.
NASA Technical Reports Server (NTRS)
Yates, Leslie A.
1992-01-01
The construction of interferograms, schlieren, and shadowgraphs from computed flowfield solutions permits one-to-one comparisons of computed and experimental results. A method for constructing these images from both ideal- and real-gas, two- and three-dimensional computed flowfields is described. The computational grids can be structured or unstructured, and multiple grids are an option. Constructed images are shown for several types of computed flows including nozzle, wake, and reacting flows; comparisons to experimental images are also shown. In addition, the sensitivity of these images to errors in the flowfield solution is demonstrated, and the constructed images can be used to identify problem areas in the computations.
Kuzmiak, Cherie Marie; Cole, Elodia B; Zeng, Donglin; Tuttle, Laura A; Steed, Doreen; Pisano, Etta D
2016-01-01
Objectives: To assess radiologist confidence in the characterization of suspicious breast lesions with a dedicated three-dimensional breast computed tomography (DBCT) system in comparison to diagnostic two-dimensional digital mammography (dxDM). Materials and Methods: Twenty women were recruited who were to undergo a breast biopsy for a Breast Imaging-Reporting and Data System (BI-RADS) 4 or 5 lesion evaluated with dxDM in this Institutional Review Board-approved study. The enrolled subjects underwent imaging of the breast(s) of concern using DBCT. Seven radiologists reviewed the cases. Each reader compared DBCT to the dxDM and was asked to specify the lesion type and BI-RADS score for each lesion and modality. They also compared lesion characteristics: Shape for masses or morphology for calcifications; and margins for masses or distribution for calcifications between the modalities using confidence scores (0–100). Results: Twenty-four biopsied lesions were included in this study: 17 (70.8%) masses and 7 (29.2%) calcifications. Eight (33.3%) lesions were malignant, and 16 (66.7%) were benign. Across all lesions, there was no significant difference in the margin/distribution (Δ = −0.99, P = 0.84) and shape/morphology (Δ = −0.10, P = 0.98) visualization confidence scores of DBCT in relation to dxDM. However, analysis by lesion type showed a statistically significant increase in reader shape (Δ =11.34, P = 0.013) and margin (Δ =9.93, P = 0.023) visualization confidence with DBCT versus dxDM for masses and significant decrease in reader morphology (Δ = −29.95, P = 0.001) and distribution (Δ = −28.62, P = 0.002) visualization confidence for calcifications. Conclusion: Reader confidence in the characterization of suspicious masses is significantly improved with DBCT, but reduced for calcifications. Further study is needed to determine whether this technology can be used for breast cancer screening. PMID:27195180
Liow, R Y; Birdsall, P D; Mucci, B; Greiss, M E
1999-10-01
Spiral computed tomography (CT) with three-dimensional and multiplanar reconstructions was used in the evaluation of tibial fractures in nine patients. Computed tomography added important information to that obtained by plain radiographs. Five (55%) fractures were reclassified. The degree of articular depression was often underappreciated on plain radiographs. Furthermore, the fracture complexity and the spatial relation of fragments could be readily demonstrated with 3-D reconstruction. This technique is useful in planning operative reconstruction. PMID:10535555
NASA Astrophysics Data System (ADS)
Clemo, T. M.; Ramarao, B.; Kelly, V. A.; Lavenue, M.
2011-12-01
Capture is a measure of the impact of groundwater pumping upon groundwater and surface water systems. The computation of capture through analytical or numerical methods has been the subject of articles in the literature for several decades (Bredehoeft et al., 1982). Most recently Leake et al. (2010) described a systematic way to produce capture maps in three-dimensional systems using a numerical perturbation approach in which capture from streams was computed using unit rate pumping at many locations within a MODFLOW model. The Leake et al. (2010) method advances the current state of computing capture. A limitation stems from the computational demand required by the perturbation approach wherein days or weeks of computational time might be required to obtain a robust measure of capture. In this paper, we present an efficient method to compute capture in three-dimensional systems based upon adjoint states. The efficiency of the adjoint method will enable uncertainty analysis to be conducted on capture calculations. The USGS and INTERA have collaborated to extend the MODFLOW Adjoint code (Clemo, 2007) to include stream-aquifer interaction and have applied it to one of the examples used in Leake et al. (2010), the San Pedro Basin MODFLOW model. With five layers and 140,800 grid blocks per layer, the San Pedro Basin model, provided an ideal example data set to compare the capture computed from the perturbation and the adjoint methods. The capture fraction map produced from the perturbation method for the San Pedro Basin model required significant computational time to compute and therefore the locations for the pumping wells were limited to 1530 locations in layer 4. The 1530 direct simulations of capture require approximately 76 CPU hours. Had capture been simulated in each grid block in each layer, as is done in the adjoint method, the CPU time would have been on the order of 4 years. The MODFLOW-Adjoint produced the capture fraction map of the San Pedro Basin model
An experimental and computational study of transonic three-dimensional flow in a turbine cascade
Camus, J.J.; Denton, J.D.; Scrivener, C.T.J.; Soulis, J.V.
1984-04-01
Detailed experimental measurements of the flow in a cascade of turbine rotor blades with a nonplanar end wall are reported. The cascade geometry was chosen to model as closely as possible that of a H.P. gas turbine rotor blade. The blade section is designed for supersonic flow with an exit Mach number of 1.15 and the experiments covered a range of exit Mach numbers from 0.7-1.2. Significant three-dimensional effects were observed and the origin of these is discussed. The measurements are compared with data for the same blade section in a two-dimensional cascade and also with the predictions of two different fully three-dimensional inviscid flow calculation methods. It is found that both these calculations predict the major threedimensional effects on the flow correctly.
Conformal mappings for computations of steady, three-dimensional, supersonic flows
NASA Technical Reports Server (NTRS)
Moretti, G.
1976-01-01
The evaluation of steady, supersonic, three-dimensional inviscid flows is considered, taking into account the construction of suitable grids on the basis of a simple conformal mapping. A description is presented of an analytical mapping technique. The technique is illustrated with the aid of examples of mappings, involving nontrivial geometries. Attention is given to a wing-fuselage cross section, a FORTRAN program for the basic mapping, the coupling of mappings, and the equations of motion.
Combined three-dimensional computer vision and epi-illumination fluorescence imaging system
NASA Astrophysics Data System (ADS)
Gorpas, Dimitris; Yova, Dido; Politopoulos, Kostas
2012-03-01
Most of the reported fluorescence imaging methods and systems highlight the need for three-dimensional information of the inspected region surface geometry. The scope of this manuscript is to introduce an epi-illumination fluorescence imaging system, which has been enhanced with a binocular machine vision system for the translation of the inverse problem solution to the global coordinates system. The epi-illumination fluorescence imaging system is consisted of a structured scanning excitation source, which increases the spatial differentiation of the measured data, and a telecentric lens, which increases the angular differentiation. On the other hand, the binocular system is based on the projection of a structured light pattern on the inspected area, for the solution of the correspondence problem between the stereo pair. The functionality of the system has been evaluated on tissue phantoms and calibration objects. The reconstruction accuracy of the fluorophores distribution, as resulted from the root mean square error between the actual distribution and the outcome of the forward solver, was more than 80%. On the other hand, the surface three-dimensional reconstruction of the inspected region presented 0.067+/-0.004 mm accuracy, as resulted from the mean Euclidean distance between the three-dimensional position of the real world points and those reconstructed.
NASA Astrophysics Data System (ADS)
Ohtani, Tomoyuki; Nakano, Tsukasa; Nakashima, Yoshito; Muraoka, Hirofumi
2001-11-01
Three-dimensional shape analysis of miarolitic cavities and enclaves from the Kakkonda granite, NE Japan, was performed by X-ray computed tomography (CT) and image analysis. The three-dimensional shape of the miarolitic cavities and enclaves was reconstructed by stacked two-dimensional CT slice images with an in-plane resolution of 0.3 mm and an inter-slice spacing of 1 mm. An ellipsoid was fitted to each reconstructed object by the image processing programs. The shortest, intermediate, and longest axes of the ellipsoids fitted to miarolitic cavities had E-W, N-S, and vertical directions, respectively. The shortest axes of the ellipsoids fitted to enclaves were sub-vertical to vertical. Three-dimensional strains calculated from miarolitic cavities and enclaves have E-W and vertical shortening, respectively. The shape characteristics of miarolitic cavities probably reflect regional stress during the late magmatic stage, and those of enclaves reflect shortening by later-intruded magma or body rotation during the early magmatic stage. The miarolitic cavities may not be strained homogeneously with the surrounding granite, because the competence of minerals is different from that of the fluid-filled cavities. Although the strain markers require sufficient contrast between their CT numbers and those of the surrounding minerals, this method has several advantages over conventional methods, including the fact that it is non-destructive, expedient, and allows direct three-dimensional observation of each object.
Aerodynamic Analyses Requiring Advanced Computers, part 2
NASA Technical Reports Server (NTRS)
1975-01-01
Papers given at the conference present the results of theoretical research on aerodynamic flow problems requiring the use of advanced computers. Topics discussed include two-dimensional configurations, three-dimensional configurations, transonic aircraft, and the space shuttle.
NASA Technical Reports Server (NTRS)
Dulikravich, D. S.
1982-01-01
A fast computer program, GRID3C, was developed for accurately generating periodic, boundary conforming, three dimensional, consecutively refined computational grids applicable to realistic axial turbomachinery geometries. The method is based on using two functions to generate two dimensional grids on a number of coaxial axisymmetric surfaces positioned between the centerbody and the outer radial boundary. These boundary fitted grids are of the C type and are characterized by quasi-orthogonality and geometric periodicity. The built in nonorthogonal coordinate stretchings and shearings cause the grid clustering in the regions of interest. The stretching parameters are part of the input to GRID3C. In its present version GRID3C can generate and store a maximum of four consecutively refined three dimensional grids. The output grid coordinates can be calculated either in the Cartesian or in the cylindrical coordinate system.
LaFleur, Karl; Cassady, Kaitlin; Doud, Alexander; Shades, Kaleb; Rogin, Eitan; He, Bin
2013-01-01
Objective At the balanced intersection of human and machine adaptation is found the optimally functioning brain-computer interface (BCI). In this study, we report a novel experiment of BCI controlling a robotic quadcopter in three-dimensional physical space using noninvasive scalp EEG in human subjects. We then quantify the performance of this system using metrics suitable for asynchronous BCI. Lastly, we examine the impact that operation of a real world device has on subjects’ control with comparison to a two-dimensional virtual cursor task. Approach Five human subjects were trained to modulate their sensorimotor rhythms to control an AR Drone navigating a three-dimensional physical space. Visual feedback was provided via a forward facing camera on the hull of the drone. Individual subjects were able to accurately acquire up to 90.5% of all valid targets presented while travelling at an average straight-line speed of 0.69 m/s. Significance Freely exploring and interacting with the world around us is a crucial element of autonomy that is lost in the context of neurodegenerative disease. Brain-computer interfaces are systems that aim to restore or enhance a user’s ability to interact with the environment via a computer and through the use of only thought. We demonstrate for the first time the ability to control a flying robot in the three-dimensional physical space using noninvasive scalp recorded EEG in humans. Our work indicates the potential of noninvasive EEG based BCI systems to accomplish complex control in three-dimensional physical space. The present study may serve as a framework for the investigation of multidimensional non-invasive brain-computer interface control in a physical environment using telepresence robotics. PMID:23735712
NASA Technical Reports Server (NTRS)
Omalley, T. A.
1984-01-01
The use of the coupled cavity traveling wave tube for space communications has led to an increased interest in improving the efficiency of the basic interaction process in these devices through velocity resynchronization and other methods. A flexible, three dimensional, axially symmetric, large signal computer program was developed for use on the IBM 370 time sharing system. A users' manual for this program is included.
NASA Astrophysics Data System (ADS)
Trell, Erik
2012-09-01
Emulating Nature by observation and ground-up application of its patterns, structures and processes is a classical scientific practice which under the designation of Biomimetics has now been brought to the Nanotechnology scale where even highly complex systems can be replicated by continuous or cyclically reiterated assembly of the respective self-similar real-world eigen-elements, modules and algorithms right from their infinitesimal origin. This is actually quite akin to the genuine mathematical art and can find valuable renewed use as here exemplified by an onedimensional prime-number line and a three-dimensional Diophantine Equation Universe embodiment.
Advances in three-dimensional integral imaging: sensing, display, and applications [Invited].
Xiao, Xiao; Javidi, Bahram; Martinez-Corral, Manuel; Stern, Adrian
2013-02-01
Three-dimensional (3D) sensing and imaging technologies have been extensively researched for many applications in the fields of entertainment, medicine, robotics, manufacturing, industrial inspection, security, surveillance, and defense due to their diverse and significant benefits. Integral imaging is a passive multiperspective imaging technique, which records multiple two-dimensional images of a scene from different perspectives. Unlike holography, it can capture a scene such as outdoor events with incoherent or ambient light. Integral imaging can display a true 3D color image with full parallax and continuous viewing angles by incoherent light; thus it does not suffer from speckle degradation. Because of its unique properties, integral imaging has been revived over the past decade or so as a promising approach for massive 3D commercialization. A series of key articles on this topic have appeared in the OSA journals, including Applied Optics. Thus, it is fitting that this Commemorative Review presents an overview of literature on physical principles and applications of integral imaging. Several data capture configurations, reconstruction, and display methods are overviewed. In addition, applications including 3D underwater imaging, 3D imaging in photon-starved environments, 3D tracking of occluded objects, 3D optical microscopy, and 3D polarimetric imaging are reviewed. PMID:23385893
Yang, Yanbing; Li, Peixu; Wu, Shiting; Li, Xinyang; Shi, Enzheng; Shen, Qicang; Wu, Dehai; Xu, Wenjing; Cao, Anyuan; Yuan, Quan
2015-04-13
Mesoporous carbon (m-C) has potential applications as porous electrodes for electrochemical energy storage, but its applications have been severely limited by the inherent fragility and low electrical conductivity. A rational strategy is presented to construct m-C into hierarchical porous structures with high flexibility by using a carbon nanotube (CNT) sponge as a three-dimensional template, and grafting Pt nanoparticles at the m-C surface. This method involves several controllable steps including solution deposition of a mesoporous silica (m-SiO2 ) layer onto CNTs, chemical vapor deposition of acetylene, and etching of m-SiO2 , resulting in a CNT@m-C core-shell or a CNT@m-C@Pt core-shell hybrid structure after Pt adsorption. The underlying CNT network provides a robust yet flexible support and a high electrical conductivity, whereas the m-C provides large surface area, and the Pt nanoparticles improves interfacial electron and ion diffusion. Consequently, specific capacitances of 203 and 311 F g(-1) have been achieved in these CNT@m-C and CNT@m-C@Pt sponges as supercapacitor electrodes, respectively, which can retain 96 % of original capacitance under large degree compression. PMID:25752493
Amsden, A.A.; O'Rourke, P.J.; Butler, T.D. ); Meintjes, K.; Fansler, T.D. )
1991-01-01
Computer simulations are compared with measurements of the three-dimensional, unsteady scavenging flows of a motored two-stroke engine. Laser Doppler velocimetry measurements were made on a modified Suzuki DT-85 ported engine. Calculations were performed using KIVA-3, a computer program that efficiently solves the intake and exhaust port flows along with those in the cylinder. Measured and computed cylinder pressures and velocities are compared. Pressures agree well over the cycle as do the velocities at the intake ports. In-cylinder velocities differ in detail, but the tumbling motion in the cylinder is well replicated in vertical plane passing through the cylinder axis. 20 refs., 7 figs., 3 tabs.
NASA Technical Reports Server (NTRS)
Gibson, S. G.
1983-01-01
A system of computer programs was developed to model general three dimensional surfaces. Surfaces are modeled as sets of parametric bicubic patches. There are also capabilities to transform coordinates, to compute mesh/surface intersection normals, and to format input data for a transonic potential flow analysis. A graphical display of surface models and intersection normals is available. There are additional capabilities to regulate point spacing on input curves and to compute surface/surface intersection curves. Input and output data formats are described; detailed suggestions are given for user input. Instructions for execution are given, and examples are shown.
Xue, Q.; Mittal, R.; Zheng, X.; Bielamowicz, S.
2012-01-01
Simulation of the phonatory flow-structure interaction has been conducted in a three-dimensional, tubular shaped laryngeal model that has been designed with a high level of realism with respect to the human laryngeal anatomy. A non-linear spring-based contact force model is also implemented for the purpose of representing contact in more general conditions, especially those associated with three-dimensional modeling of phonation in the presence of vocal fold pathologies. The model is used to study the effects of a moderate (20%) vocal-fold tension imbalance on the phonatory dynamics. The characteristic features of phonation for normal as well as tension-imbalanced vocal folds, such as glottal waveform, glottal jet evolution, mucosal wave-type vocal-fold motion, modal entrainment, and asymmetric glottal jet deflection have been discussed in detail and compared to established data. It is found that while a moderate level of tension asymmetry does not change the vibratory dynamics significantly, it can potentially lead to measurable deterioration in voice quality. PMID:22978889
Computational study of the formation and evolution of a three-dimensional gravity current
NASA Astrophysics Data System (ADS)
Ooi, Andrew; Zhu, Shuang; Zgheib, Nadim; Sivaramakrishnan, Balachandar
2015-11-01
Gravity currents occur when fluids of different density are brought together. They are relevant in many engineering applications such as the dispersion of hazardous gas cloud or the spillage heavy chemicals from marine vehicles. Thus far, most of the studies have assumed that the gravity current is two-dimensional (or ``planar'') as it travels down the slope, i.e. the gravity current is homogeneous in the spanwise direction. In this study, we utilise data from direct numerical simulation to investigate the evolution and formation of a fully three-dimensional gravity current propagating down a uniform slope. Previous theoretical studies have predicted that three-dimensional gravity current will evolve towards a ``self-similar'' circular wedge shape. Flow visualization from experiments showed that, contrary to the theoretical prediction, the gravity current takes on a shape that is more akin to a triangular wedge. Data from our direct numerical simulation agrees with the experimental observation. Furthermore, it has been found that the shape of this triangular wedge is relatively insensitive to the initial shape of the gravity current. The physical mechanisms leading to formation of this triangular shape and the entrainment properties of such a structure will be presented.
Computed myography: three-dimensional reconstruction of motor functions from surface EMG data
NASA Astrophysics Data System (ADS)
van den Doel, Kees; Ascher, Uri M.; Pai, Dinesh K.
2008-12-01
We describe a methodology called computed myography to qualitatively and quantitatively determine the activation level of individual muscles by voltage measurements from an array of voltage sensors on the skin surface. A finite element model for electrostatics simulation is constructed from morphometric data. For the inverse problem, we utilize a generalized Tikhonov regularization. This imposes smoothness on the reconstructed sources inside the muscles and suppresses sources outside the muscles using a penalty term. Results from experiments with simulated and human data are presented for activation reconstructions of three muscles in the upper arm (biceps brachii, bracialis and triceps). This approach potentially offers a new clinical tool to sensitively assess muscle function in patients suffering from neurological disorders (e.g., spinal cord injury), and could more accurately guide advances in the evaluation of specific rehabilitation training regimens.
NASA Astrophysics Data System (ADS)
Oloso, Amidu Olawale
A hybrid automatic differentiation/incremental iterative method was implemented in the general purpose advanced computational fluid dynamics code (CFL3D Version 4.1) to yield a new code (CFL3D.ADII) that is capable of computing consistently discrete first order sensitivity derivatives for complex geometries. With the exception of unsteady problems, the new code retains all the useful features and capabilities of the original CFL3D flow analysis code. The superiority of the new code over a carefully applied method of finite-differences is demonstrated. A coarse grain, scalable, distributed-memory, parallel version of CFL3D.ADII was developed based on "derivative stripmining". In this data-parallel approach, an identical copy of CFL3D.ADII is executed on each processor with different derivative input files. The effect of communication overhead on the overall parallel computational efficiency is negligible. However, the fraction of CFL3D.ADII duplicated on all processors has significant impact on the computational efficiency. To reduce the large execution time associated with the sequential 1-D line search in gradient-based aerodynamic optimization, an alternative parallel approach was developed. The execution time of the new approach was reduced effectively to that of one flow analysis, regardless of the number of function evaluations in the 1-D search. The new approach was found to yield design results that are essentially identical to those obtained from the traditional sequential approach but at much smaller execution time. The parallel CFL3D.ADII and the parallel 1-D line search are demonstrated in shape improvement studies of a realistic High Speed Civil Transport (HSCT) wing/body configuration represented by over 100 design variables and 200,000 grid points in inviscid supersonic flow on the 16 node IBM SP2 parallel computer at the Numerical Aerospace Simulation (NAS) facility, NASA Ames Research Center. In addition to making the handling of such a large
NASA Astrophysics Data System (ADS)
Vorobiev, O.; Antoun, T.; Rodgers, A.; Matzel, E.; Myers, S.; Walter, W.; Petersson, A.; Bono, C.; Sjogreen, B.
2008-12-01
Next generation methods for lowering seismic monitoring thresholds and reducing uncertainties will likely rely on complete waveform simulations using three-dimensional (3D) earth models. Recent advances in numerical methods for both non-linear (shock wave) and linear (anelastic, seismic wave) propagation, improved 3D models and the steady growth of parallel computing promise to improve the accuracy and efficiency of explosion simulations. These methods implemented in new computer codes can advance physics-based understanding of nuclear explosions as well as the propagation effects caused by path-dependent earth structure. This presentation will summarize new 3D modeling capabilities developed to improve understanding of the seismic waves emerging from an explosion. Specifically we are working in three thrust areas: 1) computation of regional distance intermediate-period (50-10 seconds) synthetic seismograms in 3D earth models to assess the ability of these models to predict observed seismograms from well-characterized events; 2) coupling of non-linear hydrodynamic simulations of explosion shock waves with an anelastic finite difference code for modeling the dependence of seismic wave observables on explosion emplacement conditions and near-source heterogeneity; and 3) implementation of surface topography in our anelastic finite difference code to include scattering and mode-conversion due to a non-planar free surface. Current 3D continental-to-global scale seismic models represent long-wavelength (greater than 100 km) heterogeneity. We are investigating the efficacy of current 3D models to predict complete intermediate (50- 10 seconds) waveforms for well-characterized events (mostly earthquakes) using the spectral element code, SPECFEM3D. Intermediate period seismograms for crustal events at regional distance are strongly impacted by path propagation effects due to laterally variable crustal and upper mantle structure. We are also modeling shock wave propagation
Rodgers, A; Matzel, E; Pasyanos, M; Petersson, A; Sjogreen, B; Bono, C; Vorobiev, O; Antoun, T; Walter, W; Myers, S; Lomov, I
2008-07-07
The development of accurate numerical methods to simulate wave propagation in three-dimensional (3D) earth models and advances in computational power offer exciting possibilities for modeling the motions excited by underground nuclear explosions. This presentation will describe recent work to use new numerical techniques and parallel computing to model earthquakes and underground explosions to improve understanding of the wave excitation at the source and path-propagation effects. Firstly, we are using the spectral element method (SEM, SPECFEM3D code of Komatitsch and Tromp, 2002) to model earthquakes and explosions at regional distances using available 3D models. SPECFEM3D simulates anelastic wave propagation in fully 3D earth models in spherical geometry with the ability to account for free surface topography, anisotropy, ellipticity, rotation and gravity. Results show in many cases that 3D models are able to reproduce features of the observed seismograms that arise from path-propagation effects (e.g. enhanced surface wave dispersion, refraction, amplitude variations from focusing and defocusing, tangential component energy from isotropic sources). We are currently investigating the ability of different 3D models to predict path-specific seismograms as a function of frequency. A number of models developed using a variety of methodologies are available for testing. These include the WENA/Unified model of Eurasia (e.g. Pasyanos et al 2004), the global CUB 2.0 model (Shapiro and Ritzwoller, 2002), the partitioned waveform model for the Mediterranean (van der Lee et al., 2007) and stochastic models of the Yellow Sea Korean Peninsula region (Pasyanos et al., 2006). Secondly, we are extending our Cartesian anelastic finite difference code (WPP of Nilsson et al., 2007) to model the effects of free-surface topography. WPP models anelastic wave propagation in fully 3D earth models using mesh refinement to increase computational speed and improve memory efficiency. Thirdly
NASA Astrophysics Data System (ADS)
Hase, Kazunori; Yokoi, Takashi
In the present study, the computer simulation technique to autonomously generate running motion from walking was developed using a three-dimensional entire-body neuro-musculo-skeletal model. When maximizing locomotive speed was employed as the evaluative criterion, the initial walking pattern could not transition to a valid running motion. When minimizing the period of foot-ground contact was added to this evaluative criterion, the simulation model autonomously produced appropriate three-dimensional running. Changes in the neuronal system showed the fatigue coefficient of the neural oscillators to reduce as locomotion patterns transitioned from walking to running. Then, when the running speed increased, the amplitude of the non-specific stimulus from the higher center increased. These two changes indicate mean that the improvement in responsiveness of the neuronal system is important for the transition process from walking to running, and that the comprehensive activation level of the neuronal system is essential in the process of increasing running speed.
NASA Technical Reports Server (NTRS)
Dorsey, D. R., Jr.
1975-01-01
A mathematical model was developed of the three-dimensional dynamics of a high-altitude scientific research balloon system perturbed from its equilibrium configuration by an arbitrary gust loading. The platform is modelled as a system of four coupled pendula, and the equations of motion were developed in the Lagrangian formalism assuming a small-angle approximation. Three-dimensional pendulation, torsion, and precessional motion due to Coriolis forces are considered. Aerodynamic and viscous damping effects on the pendulatory and torsional motions are included. A general model of the gust field incident upon the balloon system was developed. The digital computer simulation program is described, and a guide to its use is given.
Development of a three-dimensional Navier-Stokes code on CDC star-100 computer
NASA Technical Reports Server (NTRS)
Vatsa, V. N.; Goglia, G. L.
1978-01-01
A three-dimensional code in body-fitted coordinates was developed using MacCormack's algorithm. The code is structured to be compatible with any general configuration, provided that the metric coefficients for the transformation are available. The governing equations are developed in primitive variables in order to facilitate the incorporation of physical boundary conditions and turbulence-closure models. MacCormack's two-step, unsplit, time-marching algorithm is used to solve the unsteady Navier-Stokes equations until steady-state solution is achieved. Cases discussed include (1) flat plate in supersonic free stream; (2) supersonic flow along an axial corner; (3) subsonic flow in an axial corner at M infinity = 0.95; and (4) supersonic flow in an axial corner at M infinity 1.5.
Three-dimensional computations of rotordynamic force distributions in a labyrinth seal
NASA Astrophysics Data System (ADS)
Rhode, D. L.; Hensel, S. J.; Guidry, M. J.
1993-07-01
A numerical method employing a finite volume approach for calculating the rotordynamic force on eccentric, whirling labyrinth seals is presented. The SIMPLER algorithm is used to calculate the three-dimensional flowfield within a seal. The modified bipolar coordinate system used accurately describes the geometry of an eccentric seal. The turbulent flow form of the fully elliptic Navier-Stokes equations was solved. A 3-percent eccentric, single labyrinth cavity rotating at 7000 cpm was investigated for three different inlet swirl conditions, each with and without a whirl orbit frequency of 3500 cpm. It was found that the circumferential pressure variation around the downstream tooth periphery is by far the most important contribution to both rotordynamic force components. Thus, the flowfield details near each tooth throttling should be carefully considered. Further, a substantial increase of shaft whirl frequency was found to decrease and increase the effect of cavity inlet swirl on Ft and Fr, respectively.
Computation of three-dimensional temperature distribution in diode-pumped alkali vapor amplifiers
NASA Astrophysics Data System (ADS)
Shen, Binglin; Xu, Xingqi; Xia, Chunsheng; Pan, Bailiang
2016-06-01
Combining the kinetic and fluid dynamic processes in static and flowing-gas diode-pumped alkali vapor amplifiers, a comprehensive physical model with a cyclic iterative approach for calculating the three-dimensional temperature distribution of the vapor cell is established. Taking into account heat generation, thermal conductivity and convection, the excitation of the alkali atoms to high electronic levels, and their losses due to ionization in the gain medium, the thermal features and output characteristics have been simultaneously obtained. The results are in good agreement with those of the measurement in a static rubidium vapor amplifier. Influences of gas velocity on radial and axial temperature profiles are simulated and analyzed. The results have demonstrated that thermal problems in gaseous gain medium can be significantly reduced by flowing the gain medium with sufficiently high velocity.
Development Of A Three-Dimensional Circuit Integration Technology And Computer Architecture
NASA Astrophysics Data System (ADS)
Etchells, R. D.; Grinberg, J.; Nudd, G. R.
1981-12-01
This paper is the first of a series 1,2,3 describing a range of efforts at Hughes Research Laboratories, which are collectively referred to as "Three-Dimensional Microelectronics." The technology being developed is a combination of a unique circuit fabrication/packaging technology and a novel processing architecture. The packaging technology greatly reduces the parasitic impedances associated with signal-routing in complex VLSI structures, while simultaneously allowing circuit densities orders of magnitude higher than the current state-of-the-art. When combined with the 3-D processor architecture, the resulting machine exhibits a one- to two-order of magnitude simultaneous improvement over current state-of-the-art machines in the three areas of processing speed, power consumption, and physical volume. The 3-D architecture is essentially that commonly referred to as a "cellular array", with the ultimate implementation having as many as 512 x 512 processors working in parallel. The three-dimensional nature of the assembled machine arises from the fact that the chips containing the active circuitry of the processor are stacked on top of each other. In this structure, electrical signals are passed vertically through the chips via thermomigrated aluminum feedthroughs. Signals are passed between adjacent chips by micro-interconnects. This discussion presents a broad view of the total effort, as well as a more detailed treatment of the fabrication and packaging technologies themselves. The results of performance simulations of the completed 3-D processor executing a variety of algorithms are also presented. Of particular pertinence to the interests of the focal-plane array community is the simulation of the UNICORNS nonuniformity correction algorithms as executed by the 3-D architecture.
Ichijo, Yoshifumi; Takahashi, Yusuke; Tsuchiya, Mahito; Marushita, Yoichi; Sato, Toshio; Sugawara, Hitoshi; Hayashi, Shogo; Itoh, Masahiro; Takahashi, Tsuneo
2016-09-01
The aim of this study is to obtain a quantitative anatomical description of the hyoid bone and mandible using three-dimensional computed tomography. Hyoid bones were obtained from a total of 101 cadavers varying in age from 67 to 102 years. The percentage of symmetrical U-type and asymmetrical-type hyoid bones was low compared with symmetrical V type (14.9, 15.8, and 69.3 %, respectively), and no significant sex difference was observed. We found bilateral nonfusion in cadavers of advanced age at a rate of 22.7 % and bilateral complete fusion at a rate of 51.5 %. There were significant differences in metric variables (length and width) between males and females, but no significant differences in width among the different fusion types. There was no significant interaction effect of sex and degree of fusion. Strong significant associations were observed between size (length and width) of the hyoid bone and mandible in the nonfusion group, while the complete fusion group revealed a moderate correlation. We also investigated the hypothesis that the junction between the hyoid body and greater horn plays an important role in the movement of bones that have not yet ossified. However, no statistical difference was observed in the width between the two greater horns. The degree of fusion of the greater horn with the hyoid body may also affect relations of interdependencies between the hyoid bone and mandible, an important component to consider when assessing risk factors in the development of masticatory and swallowing function. PMID:26543038
NASA Technical Reports Server (NTRS)
Holland, Scott Douglas
1991-01-01
A combined computational and experimental parametric study of the internal aerodynamics of a generic three dimensional sidewall compression scramjet inlet configuration was performed. The study was designed to demonstrate the utility of computational fluid dynamics as a design tool in hypersonic inlet flow fields, to provide a detailed account of the nature and structure of the internal flow interactions, and to provide a comprehensive surface property and flow field database to determine the effects of contraction ratio, cowl position, and Reynolds number on the performance of a hypersonic scramjet inlet configuration.
NASA Technical Reports Server (NTRS)
Smith, R. E.; Pitts, J. I.
1979-01-01
The development of a vectorized computer code for the solution of the three-dimensional viscous-compressible Navier-Stokes equations is described. The code is applied on the CDC STAR-100 vector computer which is capable of achieving high result rates when a high degree of parallelism is present in the computations. The computational technique is an explicit time-split MacCormack predictor-corrector algorithm. Since a large volume of data is processed and virtual memory utilized, a data management scheme based on interleaving is used. The program has been applied to obtain the solution of the laminar supersonic flow about a family of three-dimensional corners. The equations of motion are expressed in a generalized form relative to a uniform rectangular computational domain. The metric coefficient and boundary conditions must be supplied for the corresponding physical domain. For calculations with 30,000 grid points, a computational rate of 0.00015 seconds per grid point per time step is observed.
McElrone, Andrew J.; Choat, Brendan; Parkinson, Dilworth Y.; MacDowell, Alastair A.; Brodersen, Craig R.
2013-01-01
High resolution x-ray computed tomography (HRCT) is a non-destructive diagnostic imaging technique with sub-micron resolution capability that is now being used to evaluate the structure and function of plant xylem network in three dimensions (3D) (e.g. Brodersen et al. 2010; 2011; 2012a,b). HRCT imaging is based on the same principles as medical CT systems, but a high intensity synchrotron x-ray source results in higher spatial resolution and decreased image acquisition time. Here, we demonstrate in detail how synchrotron-based HRCT (performed at the Advanced Light Source-LBNL Berkeley, CA, USA) in combination with Avizo software (VSG Inc., Burlington, MA, USA) is being used to explore plant xylem in excised tissue and living plants. This new imaging tool allows users to move beyond traditional static, 2D light or electron micrographs and study samples using virtual serial sections in any plane. An infinite number of slices in any orientation can be made on the same sample, a feature that is physically impossible using traditional microscopy methods. Results demonstrate that HRCT can be applied to both herbaceous and woody plant species, and a range of plant organs (i.e. leaves, petioles, stems, trunks, roots). Figures presented here help demonstrate both a range of representative plant vascular anatomy and the type of detail extracted from HRCT datasets, including scans for coast redwood (Sequoia sempervirens), walnut (Juglans spp.), oak (Quercus spp.), and maple (Acer spp.) tree saplings to sunflowers (Helianthus annuus), grapevines (Vitis spp.), and ferns (Pteridium aquilinum and Woodwardia fimbriata). Excised and dried samples from woody species are easiest to scan and typically yield the best images. However, recent improvements (i.e. more rapid scans and sample stabilization) have made it possible to use this visualization technique on green tissues (e.g. petioles) and in living plants. On occasion some shrinkage of hydrated green plant tissues will cause
McElrone, Andrew J; Choat, Brendan; Parkinson, Dilworth Y; MacDowell, Alastair A; Brodersen, Craig R
2013-01-01
High resolution x-ray computed tomography (HRCT) is a non-destructive diagnostic imaging technique with sub-micron resolution capability that is now being used to evaluate the structure and function of plant xylem network in three dimensions (3D) (e.g. Brodersen et al. 2010; 2011; 2012a,b). HRCT imaging is based on the same principles as medical CT systems, but a high intensity synchrotron x-ray source results in higher spatial resolution and decreased image acquisition time. Here, we demonstrate in detail how synchrotron-based HRCT (performed at the Advanced Light Source-LBNL Berkeley, CA, USA) in combination with Avizo software (VSG Inc., Burlington, MA, USA) is being used to explore plant xylem in excised tissue and living plants. This new imaging tool allows users to move beyond traditional static, 2D light or electron micrographs and study samples using virtual serial sections in any plane. An infinite number of slices in any orientation can be made on the same sample, a feature that is physically impossible using traditional microscopy methods. Results demonstrate that HRCT can be applied to both herbaceous and woody plant species, and a range of plant organs (i.e. leaves, petioles, stems, trunks, roots). Figures presented here help demonstrate both a range of representative plant vascular anatomy and the type of detail extracted from HRCT datasets, including scans for coast redwood (Sequoia sempervirens), walnut (Juglans spp.), oak (Quercus spp.), and maple (Acer spp.) tree saplings to sunflowers (Helianthus annuus), grapevines (Vitis spp.), and ferns (Pteridium aquilinum and Woodwardia fimbriata). Excised and dried samples from woody species are easiest to scan and typically yield the best images. However, recent improvements (i.e. more rapid scans and sample stabilization) have made it possible to use this visualization technique on green tissues (e.g. petioles) and in living plants. On occasion some shrinkage of hydrated green plant tissues will cause
Computer-aided three-dimensional analysis of the small-geometry effects of a MOSFET
Hsueh, K.L.K.
1987-01-01
The 3-D effects of a small-geometry MOSFET can only be analyzed accurately by using a 3-D simulator. A 3-D MOSFET simulator, called MICROMOS, therefore, was developed for this purpose. The history of numerical analysis used to simulate semiconductor devices was reviewed. Numerical methods, their mathematical background, and the iteration techniques commonly used in the semiconductor simulation are also discussed. The three-dimensional graphic results of the numerical analysis give valuable information for the understanding the physics of the small-geometry effects in a VLSI MOSFET. A mutual modulation of the depletion depth underneath the gate is described. This leads to an accurate 3-D analytical model for the prediction of the threshold voltage of a small-geometry MOSFET with a fully-recessed isolation oxide structure. Also, there is a mutual modulation between the transverse electric field and its two perpendicular components. This modulation was proven to be the source of the small-geometry effects of a small-size MOSFET. The enhanced drain-induced barrier lowering (DIBL) due to the scaling of the device is also presented.
Lens-free computational imaging of capillary morphogenesis within three-dimensional substrates.
Weidling, John; Isikman, Serhan O; Greenbaum, Alon; Ozcan, Aydogan; Botvinick, Elliot
2012-12-01
Endothelial cells cultured in three-dimensional (3-D) extracellular matrices spontaneously form microvessels in response to soluble and matrix-bound factors. Such cultures are common for the study of angiogenesis and may find widespread use in drug discovery. Vascular networks are imaged over weeks to measure the distribution of vessel morphogenic parameters. Measurements require micron-scale spatial resolution, which for light microscopy comes at the cost of limited field-of-view (FOV) and shallow depth-of-focus (DOF). Small FOVs and DOFs necessitate lateral and axial mechanical scanning, thus limiting imaging throughput. We present a lens-free holographic on-chip microscopy technique to rapidly image microvessels within a Petri dish over a large volume without any mechanical scanning. This on-chip method uses partially coherent illumination and a CMOS sensor to record in-line holographic images of the sample. For digital reconstruction of the measured holograms, we implement a multiheight phase recovery method to obtain phase images of capillary morphogenesis over a large FOV (24 mm2) with ≈ 1.5 μm spatial resolution. On average, measured capillary length in our method was within approximately 2% of lengths measured using a 10 × microscope objective. These results suggest lens-free on-chip imaging is a useful toolset for high-throughput monitoring and quantitative analysis of microvascular 3-D networks. PMID:23235893
Lens-free computational imaging of capillary morphogenesis within three-dimensional substrates
NASA Astrophysics Data System (ADS)
Weidling, John; Isikman, Serhan O.; Greenbaum, Alon; Ozcan, Aydogan; Botvinick, Elliot
2012-12-01
Endothelial cells cultured in three-dimensional (3-D) extracellular matrices spontaneously form microvessels in response to soluble and matrix-bound factors. Such cultures are common for the study of angiogenesis and may find widespread use in drug discovery. Vascular networks are imaged over weeks to measure the distribution of vessel morphogenic parameters. Measurements require micron-scale spatial resolution, which for light microscopy comes at the cost of limited field-of-view (FOV) and shallow depth-of-focus (DOF). Small FOVs and DOFs necessitate lateral and axial mechanical scanning, thus limiting imaging throughput. We present a lens-free holographic on-chip microscopy technique to rapidly image microvessels within a Petri dish over a large volume without any mechanical scanning. This on-chip method uses partially coherent illumination and a CMOS sensor to record in-line holographic images of the sample. For digital reconstruction of the measured holograms, we implement a multiheight phase recovery method to obtain phase images of capillary morphogenesis over a large FOV (24 mm2) with ˜1.5 μm spatial resolution. On average, measured capillary length in our method was within approximately 2% of lengths measured using a 10× microscope objective. These results suggest lens-free on-chip imaging is a useful toolset for high-throughput monitoring and quantitative analysis of microvascular 3-D networks.
Jets in Coronal Holes: Hinode Observations and Three-dimensional Computer Modeling
NASA Astrophysics Data System (ADS)
Moreno-Insertis, F.; Galsgaard, K.; Ugarte-Urra, I.
2008-02-01
Recent observations of coronal hole areas with the XRT and EIS instruments on board the Hinode satellite have shown with unprecedented detail the launching of fast, hot jets away from the solar surface. In some cases these events coincide with episodes of flux emergence from beneath the photosphere. In this Letter we show results of a three-dimensional numerical experiment of flux emergence from the solar interior into a coronal hole and compare them with simultaneous XRT and EIS observations of a jet-launching event that accompanied the appearance of a bipolar region in MDI magnetograms. The magnetic skeleton and topology that result in the experiment bear a strong resemblance to linear force-free extrapolations of the SOHO/MDI magnetograms. A thin current sheet is formed at the boundary of the emerging plasma. A jet is launched upward along the open reconnected field lines with values of temperature, density, and velocity in agreement with the XRT and EIS observations. Below the jet, a split-vault structure results with two chambers: a shrinking one containing the emerged field loops and a growing one with loops produced by the reconnection. The ongoing reconnection leads to a horizontal drift of the vault-and-jet structure. The timescales, velocities, and other plasma properties in the experiment are consistent with recent statistical studies of this type of event made with Hinode data.
NASA Technical Reports Server (NTRS)
Ruf, J. H.; Hagemann, G.; Immich, H.
2003-01-01
A three dimensional linear plug nozzle of area ratio 12.79 was designed by EADS Space Transportation (former Astrium Space Infrastructure). The nozzle was tested within the German National Technology Program 'LION' in a cold air wind tunnel by TU Dresden. The experimental hardware and test conditions are described. Experimental data was obtained for the nozzle without plug side wall fences at a nozzle pressure ratio of 116 and then with plug side wall fences at NPR 110. Schlieren images were recorded and axial profiles of plug wall static pressures were measured at several spanwise locations and on the plug base. Detailed CFD analysis was performed for these nozzle configurations at NPR 116 by NASA MSFC. The CFD exhibits good agreement with the experimental data. A detailed comparison of the CFD results and the experimental plug wall pressure data are given. Comparisons are made for both the without and with plug side wall fence configurations. Numerical results for density gradient are compared to experimental Schlieren images. Experimental nozzle thrust efficiencies are calculated based on the CFD results. The CFD results are used to illustrate the plug nozzle fluid dynamics. The effect of the plug side wall is emphasized.
Lens-free computational imaging of capillary morphogenesis within three-dimensional substrates
Weidling, John; Isikman, Serhan O.; Greenbaum, Alon; Ozcan, Aydogan
2012-01-01
Abstract. Endothelial cells cultured in three-dimensional (3-D) extracellular matrices spontaneously form microvessels in response to soluble and matrix-bound factors. Such cultures are common for the study of angiogenesis and may find widespread use in drug discovery. Vascular networks are imaged over weeks to measure the distribution of vessel morphogenic parameters. Measurements require micron-scale spatial resolution, which for light microscopy comes at the cost of limited field-of-view (FOV) and shallow depth-of-focus (DOF). Small FOVs and DOFs necessitate lateral and axial mechanical scanning, thus limiting imaging throughput. We present a lens-free holographic on-chip microscopy technique to rapidly image microvessels within a Petri dish over a large volume without any mechanical scanning. This on-chip method uses partially coherent illumination and a CMOS sensor to record in-line holographic images of the sample. For digital reconstruction of the measured holograms, we implement a multiheight phase recovery method to obtain phase images of capillary morphogenesis over a large FOV (24 mm2) with ∼1.5 μm spatial resolution. On average, measured capillary length in our method was within approximately 2% of lengths measured using a 10× microscope objective. These results suggest lens-free on-chip imaging is a useful toolset for high-throughput monitoring and quantitative analysis of microvascular 3-D networks. PMID:23235893
Three-dimensional segmentation of pulmonary artery volume from thoracic computed tomography imaging
NASA Astrophysics Data System (ADS)
Lindenmaier, Tamas J.; Sheikh, Khadija; Bluemke, Emma; Gyacskov, Igor; Mura, Marco; Licskai, Christopher; Mielniczuk, Lisa; Fenster, Aaron; Cunningham, Ian A.; Parraga, Grace
2015-03-01
Chronic obstructive pulmonary disease (COPD), is a major contributor to hospitalization and healthcare costs in North America. While the hallmark of COPD is airflow limitation, it is also associated with abnormalities of the cardiovascular system. Enlargement of the pulmonary artery (PA) is a morphological marker of pulmonary hypertension, and was previously shown to predict acute exacerbations using a one-dimensional diameter measurement of the main PA. We hypothesized that a three-dimensional (3D) quantification of PA size would be more sensitive than 1D methods and encompass morphological changes along the entire central pulmonary artery. Hence, we developed a 3D measurement of the main (MPA), left (LPA) and right (RPA) pulmonary arteries as well as total PA volume (TPAV) from thoracic CT images. This approach incorporates segmentation of pulmonary vessels in cross-section for the MPA, LPA and RPA to provide an estimate of their volumes. Three observers performed five repeated measurements for 15 ex-smokers with ≥10 pack-years, and randomly identified from a larger dataset of 199 patients. There was a strong agreement (r2=0.76) for PA volume and PA diameter measurements, which was used as a gold standard. Observer measurements were strongly correlated and coefficients of variation for observer 1 (MPA:2%, LPA:3%, RPA:2%, TPA:2%) were not significantly different from observer 2 and 3 results. In conclusion, we generated manual 3D pulmonary artery volume measurements from thoracic CT images that can be performed with high reproducibility. Future work will involve automation for implementation in clinical workflows.
2012-01-01
Background Recent studies reported on the very complex morphology of the pulp system in equine cheek teeth. The continuous production of secondary dentine leads to distinct age-related changes of the endodontic cavity. Detailed anatomical knowledge of the dental cavities in all ages is required to explain the aetiopathology of typical equine endodontic diseases. Furthermore, data on mandibular and maxillary pulp systems is in high demand to provide a basis for the development of endodontic therapies. However, until now examination of the pulp cavity has been based on either sectioned teeth or clinical computed tomography. More precise results were expected by using micro-computed tomography with a resolution of about 0.1 mm and three-dimensional reconstructions based on previous greyscale analyses and histological verification. The aim of the present study was to describe the physiological configurations of the pulp system within a wide spectrum of tooth ages. Results Maxillary teeth: All morphological constituents of the endodontic cavity were present in teeth between 4 and 16 years: Triadan 06s displayed six pulp horns and five root canals, Triadan 07-10s five pulp horns and four root canals and Triadan 11s seven pulp horns and four to six root canals. A common pulp chamber was most frequent in teeth ≤5 years, but was found even in a tooth of 9 years. A large variety of pulp configurations was observed within 2.5 and 16 years post eruption, but most commonly a separation into mesial and distal pulp compartments was seen. Maxillary cheek teeth showed up to four separate pulp compartments but the frequency of two, three and four pulp compartments was not related to tooth age (P > 0.05). In Triadan 06s, pulp horn 6 was always connected to pulp horns 1 and 3 and root canal I. In Triadan 11s, pulp horns 7 and 8 were present in variable constitutions. Mandibular teeth: A common pulp chamber was present in teeth up to 15 years, but most commonly seen in teeth ≤5
NASA Astrophysics Data System (ADS)
Hansen, John A.; Barnett, Michael; Makinster, James G.; Keating, Thomas
2004-11-01
The increased availability of computational modeling software has created opportunities for students to engage in scientific inquiry through constructing computer-based models of scientific phenomena. However, despite the growing trend of integrating technology into science curricula, educators need to understand what aspects of these technologies promote student learning. This study used a multi-method research approach involving both quantitative (Paper 1) and qualitative data (Paper 2) to examine student conceptual understanding of astronomical phenomena, relative to two different instructional experiences. Specifically, based on students' understandings of both spatial and declarative knowledge, we compared students who had constructed three-dimensional computational models with students who had experienced traditional lecture-based instruction. Quantitative analysis of pre-interview and post-interview data revealed that construction of three-dimensional models best facilitated student understandings of spatially related astronomical concepts -- whereas traditional instruction techniques best facilitated student understandings of fact-oriented astronomical knowledge. This paper is the first in a two-paper set that continues our line of research into whether problem-based courses such as the Virtual Solar System course can be used as a viable alternative to traditional lecture-based astronomy courses.
Advances in three-dimensional rapid prototyping of microfluidic devices for biological applications
O'Neill, P. F.; Ben Azouz, A.; Vázquez, M.; Liu, J.; Marczak, S.; Slouka, Z.; Chang, H. C.; Diamond, D.; Brabazon, D.
2014-01-01
The capability of 3D printing technologies for direct production of complex 3D structures in a single step has recently attracted an ever increasing interest within the field of microfluidics. Recently, ultrafast lasers have also allowed developing new methods for production of internal microfluidic channels within the bulk of glass and polymer materials by direct internal 3D laser writing. This review critically summarizes the latest advances in the production of microfluidic 3D structures by using 3D printing technologies and direct internal 3D laser writing fabrication methods. Current applications of these rapid prototyped microfluidic platforms in biology will be also discussed. These include imaging of cells and living organisms, electrochemical detection of viruses and neurotransmitters, and studies in drug transport and induced-release of adenosine triphosphate from erythrocytes. PMID:25538804
NASA Technical Reports Server (NTRS)
Wang, Qun-Zhen; Massey, Steven J.; Abdol-Hamid, Khaled S.; Frink, Neal T.
1999-01-01
USM3D is a widely-used unstructured flow solver for simulating inviscid and viscous flows over complex geometries. The current version (version 5.0) of USM3D, however, does not have advanced turbulence models to accurately simulate complicated flows. We have implemented two modified versions of the original Jones and Launder k-epsilon two-equation turbulence model and the Girimaji algebraic Reynolds stress model in USM3D. Tests have been conducted for two flat plate boundary layer cases, a RAE2822 airfoil and an ONERA M6 wing. The results are compared with those of empirical formulae, theoretical results and the existing Spalart-Allmaras one-equation model.
Advances in three-dimensional rapid prototyping of microfluidic devices for biological applications.
O'Neill, P F; Ben Azouz, A; Vázquez, M; Liu, J; Marczak, S; Slouka, Z; Chang, H C; Diamond, D; Brabazon, D
2014-09-01
The capability of 3D printing technologies for direct production of complex 3D structures in a single step has recently attracted an ever increasing interest within the field of microfluidics. Recently, ultrafast lasers have also allowed developing new methods for production of internal microfluidic channels within the bulk of glass and polymer materials by direct internal 3D laser writing. This review critically summarizes the latest advances in the production of microfluidic 3D structures by using 3D printing technologies and direct internal 3D laser writing fabrication methods. Current applications of these rapid prototyped microfluidic platforms in biology will be also discussed. These include imaging of cells and living organisms, electrochemical detection of viruses and neurotransmitters, and studies in drug transport and induced-release of adenosine triphosphate from erythrocytes. PMID:25538804
Advances in Light-based Imaging of Three-Dimensional Cellular Ultrastructure
Kanchanawong, Pakorn; Waterman, Clare M.
2012-01-01
Visualization methods are key to gaining insights into cellular structure and function. Since diffraction has long confined optical microscopes to a resolution no better than hundreds of nanometers, the observation of ultrastructural features has traditionally been the domain of electron microscopes (EM). In the past decade, however, advances in super-resolution fluorescence microscopy have considerably expanded the capability of light-based imaging techniques. Advantages of fluorescent labeling such as high sensitivity, specificity, and multichannel capability, can now be exploited to dissect ultrastructural features of cells. With recent methods capable of imaging specific proteins with a resolution on the order of a few tens of nanometers in 3-dimensions, this has made it possible to elucidate the molecular organization of many complex cellular structures. PMID:22209239
NASA Technical Reports Server (NTRS)
1991-01-01
Advanced concepts in hardware, software and algorithms are being pursued for application in next generation space computers and for ground based analysis of space data. The research program focuses on massively parallel computation and neural networks, as well as optical processing and optical networking which are discussed under photonics. Also included are theoretical programs in neural and nonlinear science, and device development for magnetic and ferroelectric memories.
Doud, Alexander J.; Lucas, John P.; Pisansky, Marc T.; He, Bin
2011-01-01
Brain-computer interfaces (BCIs) allow a user to interact with a computer system using thought. However, only recently have devices capable of providing sophisticated multi-dimensional control been achieved non-invasively. A major goal for non-invasive BCI systems has been to provide continuous, intuitive, and accurate control, while retaining a high level of user autonomy. By employing electroencephalography (EEG) to record and decode sensorimotor rhythms (SMRs) induced from motor imaginations, a consistent, user-specific control signal may be characterized. Utilizing a novel method of interactive and continuous control, we trained three normal subjects to modulate their SMRs to achieve three-dimensional movement of a virtual helicopter that is fast, accurate, and continuous. In this system, the virtual helicopter's forward-backward translation and elevation controls were actuated through the modulation of sensorimotor rhythms that were converted to forces applied to the virtual helicopter at every simulation time step, and the helicopter's angle of left or right rotation was linearly mapped, with higher resolution, from sensorimotor rhythms associated with other motor imaginations. These different resolutions of control allow for interplay between general intent actuation and fine control as is seen in the gross and fine movements of the arm and hand. Subjects controlled the helicopter with the goal of flying through rings (targets) randomly positioned and oriented in a three-dimensional space. The subjects flew through rings continuously, acquiring as many as 11 consecutive rings within a five-minute period. In total, the study group successfully acquired over 85% of presented targets. These results affirm the effective, three-dimensional control of our motor imagery based BCI system, and suggest its potential applications in biological navigation, neuroprosthetics, and other applications. PMID:22046274
Three-Dimensional Imaging and Image Displays: Surgical Application of Advanced Technologies.
Satava
1996-09-01
One of the cornerstones of modern technology that was ushered in by laparoscopic surgery is the use of the video image. The importance of this "virtual representation" of the patient goes well beyond the application to laparoscopic surgery, and lies at the very heart of the revolution of surgery into the Information Age. Real objects, organs and patients can be represented as 2 and 3-dimensional computer generated images and viewed upon displays beyond the simple video monitor which permit a level of clinical practice not possible on the actual patients. These fundamental concepts that form the foundation of the revolution in surgery are placed in a framework for the future of surgery, and illustrate how their implementation can dramatically improve patient care. PMID:10401122
NASA Astrophysics Data System (ADS)
Xavier, M. P.; do Nascimento, T. M.; dos Santos, R. W.; Lobosco, M.
2014-03-01
The development of computational systems that mimics the physiological response of organs or even the entire body is a complex task. One of the issues that makes this task extremely complex is the huge computational resources needed to execute the simulations. For this reason, the use of parallel computing is mandatory. In this work, we focus on the simulation of temporal and spatial behaviour of some human innate immune system cells and molecules in a small three-dimensional section of a tissue. To perform this simulation, we use multiple Graphics Processing Units (GPUs) in a shared-memory environment. Despite of high initialization and communication costs imposed by the use of GPUs, the techniques used to implement the HIS simulator have shown to be very effective to achieve this purpose.
NASA Astrophysics Data System (ADS)
Mur, G.
An efficient and accurate finite-element package is described for computing transient as well as time-harmonic three-dimensional electromagnetic fields in inhomogeneous media. For the expansion of the field in an inhomogeneous configuration, edge elements are used along the interfaces between media with different medium properties to allow for the continuity conditions of the field across these interfaces, nodal elements are used in the remaining homogeneous subdomains. In the domain of computation the package decides locally what type of element has to be used for obtaining the user-specified accuracy of modeling the field. In this way optimum results are obtained both in regard to computational efficiency and in regard to desired accuracy. The electromagnetic compatibility relations are implemented for avoiding spurious solutions.
NASA Technical Reports Server (NTRS)
Bartels, Robert E.
1999-01-01
This paper presents a modification of the spring analogy scheme which uses axial linear spring stiffness with selective spring stiffening/relaxation. An alternate approach to solving the geometric conservation law is taken which eliminates the need for storage of metric Jacobians at previous time steps. Efficiency and verification are illustrated with several unsteady 2-D airfoil Euler computations. The method is next applied to the computation of the turbulent flow about a 2-D airfoil and wing with two and three- dimensional moving spoiler surfaces, and the results compared with Benchmark Active Controls Technology (BACT) experimental data. The aeroelastic response at low dynamic pressure of an airfoil to a single large scale oscillation of a spoiler surface is computed. This study confirms that it is possible to achieve accurate solutions with a very large time step for aeroelastic problems using the fluid solver and aeroelastic integrator as discussed in this paper.
NASA Technical Reports Server (NTRS)
Wang, R.; Demerdash, N. A.
1990-01-01
The effects of finite element grid geometries and associated ill-conditioning were studied in single medium and multi-media (air-iron) three dimensional magnetostatic field computation problems. The sensitivities of these 3D field computations to finite element grid geometries were investigated. It was found that in single medium applications the unconstrained magnetic vector potential curl-curl formulation in conjunction with first order finite elements produce global results which are almost totally insensitive to grid geometries. However, it was found that in multi-media (air-iron) applications first order finite element results are sensitive to grid geometries and consequent elemental shape ill-conditioning. These sensitivities were almost totally eliminated by means of the use of second order finite elements in the field computation algorithms. Practical examples are given in this paper to demonstrate these aspects mentioned above.
Computer-Generated, Three-Dimensional Character Animation: A Report and Analysis.
ERIC Educational Resources Information Center
Kingsbury, Douglas Lee
This master's thesis details the experience gathered in the production "Snoot and Muttly," a short character animation with 3-D computer generated images, and provides an analysis of the computer-generated 3-D character animation system capabilities. Descriptions are provided of the animation environment at the Ohio State University Computer…
Tsoukias, Nikolaos M.; Goldman, Daniel; Vadapalli, Arjun; Pittman, Roland N.; Popel, Aleksander S.
2009-01-01
A detailed computational model is developed to simulate oxygen transport from a three-dimensional microvascular network to surrounding tissue in the presence of hemoglobin-based oxygen carriers. The model accounts for nonlinear O2 consumption, myoglobin facilitated diffusion and nonlinear oxyhemoglobin dissociation in the RBCs and plasma. It also includes a detailed description of intravascular resistance to O2 transport and is capable of incorporating realistic three-dimensional microvascular network geometries. Simulations in this study were performed using a computer-generated microvascular architecture that mimics morphometric parameters for the hamster cheek pouch retractor muscle. Theoretical results are presented next to corresponding experimental data. Phosphoresence quenching microscopy provided PO2 measurements at the arteriolar and venular ends of capillaries in the hamster retractor muscle before and after isovolemic hemodilution with three different hemodilutents; a non-oxygen-carrying plasma expander and two hemoglobin solutions with different oxygen affinities. Sample results in a microvascular network show an enhancement of diffusive shunting between arterioles, venules and capillaries and a decrease in hemoglobin’s effectiveness for tissue oxygenation when its affinity for O2 is decreased. Model simulations suggest that microvascular network anatomy can affect the optimal hemoglobin affinity for reducing tissue hypoxia. O2 transport simulations in realistic representations of microvascular networks should provide a theoretical framework for choosing optimal parameter values in the development of hemoglobin-based blood-substitutes. PMID:17686494
Xiao, Nan; Humphrey, Jay D.; Figueroa, C. Alberto
2013-07-01
In this article, we present a computational multi-scale model of fully three-dimensional and unsteady hemodynamics within the primary large arteries in the human. Computed tomography image data from two different patients were used to reconstruct a nearly complete network of the major arteries from head to foot. A linearized coupled-momentum method for fluid–structure-interaction was used to describe vessel wall deformability and a multi-domain method for outflow boundary condition specification was used to account for the distal circulation. We demonstrated that physiologically realistic results can be obtained from the model by comparing simulated quantities such as regional blood flow, pressure and flow waveforms, and pulse wave velocities to known values in the literature. We also simulated the impact of age-related arterial stiffening on wave propagation phenomena by progressively increasing the stiffness of the central arteries and found that the predicted effects on pressure amplification and pulse wave velocity are in agreement with findings in the clinical literature. This work demonstrates the feasibility of three-dimensional techniques for simulating hemodynamics in a full-body compliant arterial network.
Chien, T.H.; Domanus, H.M.; Sha, W.T.
1993-02-01
The COMMIX-PPC computer program is an extended and improved version of earlier COMMIX codes and is specifically designed for evaluating the thermal performance of power plant condensers. The COMMIX codes are general-purpose computer programs for the analysis of fluid flow and heat transfer in complex industrial systems. In COMMIX-PPC, two major features have been added to previously published COMMIX codes. One feature is the incorporation of one-dimensional conservation of mass. momentum, and energy equations on the tube side, and the proper accounting for the thermal interaction between shell and tube side through the porous medium approach. The other added feature is the extension of the three-dimensional conservation equations for shell-side flow to treat the flow of a multicomponent medium. COMMIX-PPC is designed to perform steady-state and transient three-dimensional analysis of fluid flow with heat transfer in a power plant condenser. However, the code is designed in a generalized fashion so that, with some modification. it can be used to analyze processes in any heat exchanger or other single-phase engineering applications.
Chien, T.H.; Domanus, H.M.; Sha, W.T.
1993-02-01
The COMMIX-PPC computer pregrain is an extended and improved version of earlier COMMIX codes and is specifically designed for evaluating the thermal performance of power plant condensers. The COMMIX codes are general-purpose computer programs for the analysis of fluid flow and heat transfer in complex Industrial systems. In COMMIX-PPC, two major features have been added to previously published COMMIX codes. One feature is the incorporation of one-dimensional equations of conservation of mass, momentum, and energy on the tube stile and the proper accounting for the thermal interaction between shell and tube side through the porous-medium approach. The other added feature is the extension of the three-dimensional conservation equations for shell-side flow to treat the flow of a multicomponent medium. COMMIX-PPC is designed to perform steady-state and transient. Three-dimensional analysis of fluid flow with heat transfer tn a power plant condenser. However, the code is designed in a generalized fashion so that, with some modification, it can be used to analyze processes in any heat exchanger or other single-phase engineering applications. Volume I (Equations and Numerics) of this report describes in detail the basic equations, formulation, solution procedures, and models for a phenomena. Volume II (User's Guide and Manual) contains the input instruction, flow charts, sample problems, and descriptions of available options and boundary conditions.
Performing three-dimensional neutral particle transport calculations on tera scale computers
Woodward, C S; Brown, P N; Chang, B; Dorr, M R; Hanebutte, U R
1999-01-12
A scalable, parallel code system to perform neutral particle transport calculations in three dimensions is presented. To utilize the hyper-cluster architecture of emerging tera scale computers, the parallel code successfully combines the MPI message passing and paradigms. The code's capabilities are demonstrated by a shielding calculation containing over 14 billion unknowns. This calculation was accomplished on the IBM SP ''ASCI-Blue-Pacific computer located at Lawrence Livermore National Laboratory (LLNL).
Three-dimensional display system for medical imaging with computer-generated integral photography
NASA Astrophysics Data System (ADS)
Nakajima, Susumu; Masamune, Ken; Sakuma, Ichiro; Dohi, Takeyoshi
2000-05-01
A 3D display system for medical image by computer-generated integral photography (IP) has been developed. A new, fast, 3D-rendering algorithm has been devised to overcome the difficulties that have prevented practical application of computer-generated IP, namely, the cost of computation, and the pseudoscopic image problem. The display system as developed requires on ly a personal computer, a liquid crystal display (LCD), and a fly's eye lens (FEL). Each point in 3D space is reconstructed by the convergence of rays from many pixels on the LCD through the FEL. As the number of such points is limited by the low resolution of the LCD, the algorithm computes a coordinate of the best point for each pixel of the LCD. This reduces computation, performs hidden surface removal and solves the pseudoscopic image problem. In tests of the system, the locations of images projected 10-40 mm distant from the display were found to be less than 2.5 mm in error. Both stationary and moving IP images of a colored skull, generated from 3D computerized tomography, were projected and could be observed with motion parallax within 10 degrees, both horizontally and vertically, from the front of the display. It can be concluded that the simplicity of design and the geometrical accuracy of projection give this system significant advantages over other 3D display methods.
Ramamurti, Ravi; Sandberg, William C; Löhner, Rainald; Walker, Jeffrey A; Westneat, Mark W
2002-10-01
Many fishes that swim with the paired pectoral fins use fin-stroke parameters that produce thrust force from lift in a mechanism of underwater flight. These locomotor mechanisms are of interest to behavioral biologists, biomechanics researchers and engineers. In the present study, we performed the first three-dimensional unsteady computations of fish swimming with oscillating and deforming fins. The objective of these computations was to investigate the fluid dynamics of force production associated with the flapping aquatic flight of the bird wrasse Gomphosus varius. For this computational work, we used the geometry of the wrasse and its pectoral fin, and previously measured fin kinematics, as the starting points for computational investigation of three-dimensional (3-D) unsteady fluid dynamics. We performed a 3-D steady computation and a complete set of 3-D quasisteady computations for a range of pectoral fin positions and surface velocities. An unstructured, grid-based, unsteady Navier-Stokes solver with automatic adaptive remeshing was then used to compute the unsteady flow about the wrasse through several complete cycles of pectoral fin oscillation. The shape deformation of the pectoral fin throughout the oscillation was taken from the experimental kinematics. The pressure distribution on the body of the bird wrasse and its pectoral fins was computed and integrated to give body and fin forces which were decomposed into lift and thrust. The velocity field variation on the surface of the wrasse body, on the pectoral fins and in the near-wake was computed throughout the swimming cycle. We compared our computational results for the steady, quasi-steady and unsteady cases with the experimental data on axial and vertical acceleration obtained from the pectoral fin kinematics experiments. These comparisons show that steady state computations are incapable of describing the fluid dynamics of flapping fins. Quasi-steady state computations, with correct incorporation of
Spectral element computation of high-frequency leaky modes in three-dimensional solid waveguides
NASA Astrophysics Data System (ADS)
Treyssède, F.
2016-06-01
A numerical method is proposed to compute high-frequency low-leakage modes in structural waveguides surrounded by infinite solid media. In order to model arbitrary shape structures, a waveguide formulation is used, which consists of applying to the elastodynamic equilibrium equations a space Fourier transform along the waveguide axis and then a discretization method to the cross-section coordinates. However several numerical issues must be faced related to the unbounded nature of the cross-section, the number of degrees of freedom required to achieve an acceptable error in the high-frequency regime as well as the number of modes to compute. In this paper, these issues are circumvented by applying perfectly matched layers (PML) along the cross-section directions, a high-order spectral element method for the discretization of the cross-section, and an eigensolver shift suited for the computation of low-leakage modes. First, computations are performed for an embedded cylindrical bar, for which literature results are available. The proposed PML waveguide formulation yields good agreement with literature results, even in the case of weak impedance contrast. Its performance with high-order spectral elements is assessed in terms of convergence and accuracy and compared to traditional low-order finite elements. Then, computations are performed for an embedded square bar. Dispersion curves exhibit strong similarities with cylinders. These results show that the properties of low-leakage modes observed in cylindrical bars can also occur in other types of geometry.
Three-dimensional compressible turbulent computations for a diffusing S-duct
NASA Technical Reports Server (NTRS)
Smith, C. F.; Bruns, J. E.; Harloff, G. J.; Debonis, J. R.
1992-01-01
The purpose of the present study was to evaluate the capability of the computational fluid dynamics computer program PARC3D to model flow in a typical diffusing subsonic S-duct, with strong secondary flows. This evaluation is needed to provide confidence in the analysis of aircraft inlets, which have similar geometries. The performance predictions include total pressure profiles, static pressures, velocity profiles, boundary layer data, and skin friction data. Flow in the S-duct is subsonic, and the boundary layers are assumed to be turbulent. The results for both H and O grid solutions, are compared with existing test data.
NASA Technical Reports Server (NTRS)
Williams, Steven P.; Parrish, Russell V.
1992-01-01
Three-dimensional pictorial displays incorporating depth cues by means of stereopsis offer a potential means of presenting information in a natural way to enhance situational awareness and improve operator performance. Conventional computational techniques rely on asymptotic projection transformations and symmetric clipping to produce the stereo display. Implementation of two new computational techniques, as asymmetric clipping algorithm and piecewise linear projection transformation, provides the display designer with more control and better utilization of the effective depth-viewing volume to allow full exploitation of stereopsis cuing. Asymmetric clipping increases the perceived field of view (FOV) for the stereopsis region. The total horizontal FOV provided by the asymmetric clipping algorithm is greater throughout the scene viewing envelope than that of the symmetric algorithm. The new piecewise linear projection transformation allows the designer to creatively partition the depth-viewing volume, with freedom to place depth cuing at the various scene distances at which emphasis is desired.
Tripathi, Saroj R; Sugiyama, Yuya; Murate, Kosuke; Imayama, Kazuki; Kawase, Kodo
2016-03-21
We demonstrate a high dynamic range, three-dimensional (3-D) terahertz (THz) wave computed tomography system in which frequency tunable, Fourier transform-limited, high-power THz waves are emitted by an injection-seeded parametric source and ultrasensitive detection of THz waves is accomplished by heterodyne detection. This system covers the frequency range of 0.95 to 2.7 THz and has a maximum dynamic range in excess of nine orders of magnitude, enabling the acquisition of high-resolution 3-D tomographic images of samples with strong THz absorption. As an illustration, we obtained 3-D computed tomographic images of a pencil and a plastic product with an internal defect that demonstrates the potential applications of our imaging system in non-destructive testing and evaluation of industrial products. PMID:27136834
A computational approach to continuum damping of Alfvén waves in two and three-dimensional geometry
NASA Astrophysics Data System (ADS)
Könies, Axel; Kleiber, Ralf
2012-12-01
While the usual way of calculating continuum damping of global Alfvén modes is the introduction of a small artificial resistivity, we present a computational approach to the problem based on a suitable path of integration in the complex plane. This approach is implemented by the Riccati shooting method and it is shown that it can be transferred to the Galerkin method used in three-dimensional ideal magneto-hydrodynamics (MHD) codes. The new approach turns out to be less expensive with respect to resolution and computation time than the usual one. We present an application to large aspect ratio tokamak and stellarator equilibria retaining a few Fourier harmonics only and calculate eigenfunctions and continuum damping rates. These may serve as an input for kinetic MHD hybrid models making it possible to bypass the problem of having singularities on the path of integration on one hand and considering continuum damping on the other.
Three-Dimensional Computer Animated Graphics: A Tool for Spatial Skill Instruction.
ERIC Educational Resources Information Center
Zavotka, Susan Lee
1987-01-01
Describes study of home economics students at Ohio State University that investigated whether computer animated graphics that replicate mental images of rotation and dimensional transformation would be useful in the development of spatial skills. Orthographic drawings are described, and results for treatment and control groups are analyzed. (29…
Three-dimensional Computational Fluid Dynamics Investigation of a Spinning Helicopter Slung Load
NASA Technical Reports Server (NTRS)
Theorn, J. N.; Duque, E. P. N.; Cicolani, L.; Halsey, R.
2005-01-01
After performing steady-state Computational Fluid Dynamics (CFD) calculations using OVERFLOW to validate the CFD method against static wind-tunnel data of a box-shaped cargo container, the same setup was used to investigate unsteady flow with a moving body. Results were compared to flight test data previously collected in which the container is spinning.
Computational methods for a three-dimensional model of the petroleum-discovery process
Schuenemeyer, J.H.; Bawiec, W.J.; Drew, L.J.
1980-01-01
A discovery-process model devised by Drew, Schuenemeyer, and Root can be used to predict the amount of petroleum to be discovered in a basin from some future level of exploratory effort: the predictions are based on historical drilling and discovery data. Because marginal costs of discovery and production are a function of field size, the model can be used to make estimates of future discoveries within deposit size classes. The modeling approach is a geometric one in which the area searched is a function of the size and shape of the targets being sought. A high correlation is assumed between the surface-projection area of the fields and the volume of petroleum. To predict how much oil remains to be found, the area searched must be computed, and the basin size and discovery efficiency must be estimated. The basin is assumed to be explored randomly rather than by pattern drilling. The model may be used to compute independent estimates of future oil at different depth intervals for a play involving multiple producing horizons. We have written FORTRAN computer programs that are used with Drew, Schuenemeyer, and Root's model to merge the discovery and drilling information and perform the necessary computations to estimate undiscovered petroleum. These program may be modified easily for the estimation of remaining quantities of commodities other than petroleum. ?? 1980.
THREE-DIMENSIONAL COMPUTER MODELING OF THE HUMAN UPPER RESPIRATORY TRACT
ABSTRACT
Computer simulations of airflow and particle transport phenomena within the human respiratory system have important applications to aerosol therapy (e.g., the targeted delivery of inhaled drugs) and inhalation toxicology (e.g., the risk assessment of air pollutants). ...
Three-Dimensional Effects on Multi-Element High Lift Computations
NASA Technical Reports Server (NTRS)
Rumsey, Christopher L.; Lee-Rausch, Elizabeth M.; Watson, Ralph D.
2002-01-01
In an effort to discover the causes for disagreement between previous 2-D computations and nominally 2-D experiment for flow over the 3-clement McDonnell Douglas 30P-30N airfoil configuration at high lift, a combined experimental/CFD investigation is described. The experiment explores several different side-wall boundary layer control venting patterns, document's venting mass flow rates, and looks at corner surface flow patterns. The experimental angle of attack at maximum lift is found to be sensitive to the side wall venting pattern: a particular pattern increases the angle of attack at maximum lift by at least 2 deg. A significant amount of spanwise pressure variation is present at angles of attack near maximum lift. A CFD study using 3-D structured-grid computations, which includes the modeling of side-wall venting, is employed to investigate 3-D effects of the flow. Side-wall suction strength is found to affect the angle at which maximum lift is predicted. Maximum lift in the CFD is shown to be limited by the growth of all off-body corner flow vortex and consequent increase in spanwise pressure variation and decrease in circulation. The 3-D computations with and without wall venting predict similar trends to experiment at low angles of attack, but either stall too earl or else overpredict lift levels near maximum lift by as much as 5%. Unstructured-grid computations demonstrate that mounting brackets lower die the levels near maximum lift conditions.
ERIC Educational Resources Information Center
Smith, Alan D.
The use of computer graphic techniques with basic student enrollment statistics is examined to promote understanding of changes in student flow as a function of spatial distribution. Basic initial student enrollment data that serve as input into predictive flow models were modeled at Eastern Kentucky University. The following commercially…
Bandini, B.R. Los Alamos National Lab., NM
1990-05-01
No present light water reactor accident analysis code employs both high state of the art neutronics and thermal-hydraulics computational algorithms. Adding a modern three-dimensional neutron kinetics model to the present TRAC-PFI/MOD2 code would create a fully up to date pressurized water reactor accident evaluation code. After reviewing several options, it was decided that the Nodal Expansion Method would best provide the basis for this multidimensional transient neutronic analysis capability. Steady-state and transient versions of the Nodal Expansion Method were coded in both three-dimensional Cartesian and cylindrical geometries. In stand-alone form this method of solving the few group neutron diffusion equations was shown to yield efficient and accurate results for a variety of steady-state and transient benchmark problems. The Nodal Expansion Method was then incorporated into TRAC-PFl/MOD2. The combined NEM/TRAC code results agreed well with the EPRI-ARROTTA core-only transient analysis code when modelling a severe PWR control rod ejection accident.
Kim, Sang-Rok; Lee, Kyung-Min; Cho, Jin-Hyoung; Hwang, Hyeon-Shik
2016-04-01
An anatomical relationship between the hard and soft tissues of the face is mandatory for facial reconstruction. The purpose of this study was to investigate the positions of the eyeball and canthi three-dimensionally from the relationships between the facial hard and soft tissues using cone-beam computed tomography (CBCT). CBCT scan data of 100 living subjects were used to obtain the measurements of facial hard and soft tissues. Stepwise multiple regression analyses were carried out using the hard tissue measurements in the orbit, nasal bone, nasal cavity and maxillary canine to predict the most probable positions of the eyeball and canthi within the orbit. Orbital width, orbital height, and orbital depth were strong predictors of the eyeball and canthi position. Intercanine width was also a predictor of the mediolateral position of the eyeball. Statistically significant regression models for the positions of the eyeball and canthi could be derived from the measurements of orbit and maxillary canine. These results suggest that CBCT data can be useful in predicting the positions of the eyeball and canthi three-dimensionally. PMID:26921985
Nomura, Tsutomu; Ushio, Munetaka; Kondo, Kenji; Yamasoba, Tatsuya
2015-11-01
The purpose of this research is to determine the cause of nasal perforation symptoms and to predict post-operative function after nasal perforation repair surgery. A realistic three-dimensional (3D) model of the nose with a septal perforation was reconstructed using a computed tomography (CT) scan from a patient with nasal septal defect. The numerical simulation was carried out using ANSYS CFX V13.0. Pre- and post-operative models were compared by their velocity, pressure gradient (PG), wall shear (WS), shear strain rate (SSR) and turbulence kinetic energy in three plains. In the post-operative state, the crossflows had disappeared, and stream lines bound to the olfactory cleft area had appeared. After surgery, almost all of high-shear stress areas were disappeared comparing pre-operative model. In conclusion, the effects of surgery to correct nasal septal perforation were evaluated using a three-dimensional airflow evaluation. Following the surgery, crossflows disappeared, and WS, PG and SSR rate were decreased. A high WS.PG and SSR were suspected as causes of nasal perforation symptoms. PMID:25503100
Iskander, S.K.
1981-02-01
Two finite element (FE) approaches were used to calculate opening mode I stress intensity factors (K/sub I/) in two- or three-dimensional (2-D and 3-D) problems for the Heavy-Section Steel Technology (HSST) program. For problems that can be modeled in two dimensions, two techniques were used. One of these may be termed an ''energy release rate'' technique, and the other is based on the classical near-tip displacement and stress field equations. For three-dimensional problems, only the latter technique was used. In the energy release technique, K/sub I/ is calculated as the change in potential energy of the structure due to a small change in crack length. The potential energy is calculated by the FE method but without completely solving the system of linear equations for the displacements. Furthermore, the system of linear equations is only slightly perturbed by the change in crack length and, therefore, many computations need not be repeated for the second structure with the slight change in crack length. Implementation of these last two items has resulted in considerable savings in the calculation of K/sub I/ as compared to two complete FE analyses. These ideas are incorporated in the FMECH code. The accuracy of the methods has been checked by comparing the results of the two approaches with each other and with closed form solutions. It is estimated that the accuracy of the results is about +-5%.
Computational experience with a three-dimensional rotary engine combustion model
NASA Technical Reports Server (NTRS)
Raju, M. S.; Willis, E. A.
1990-01-01
A new computer code was developed to analyze the chemically reactive flow and spray combustion processes occurring inside a stratified-charge rotary engine. Mathematical and numerical details of the new code were recently described by the present authors. The results are presented of limited, initial computational trials as a first step in a long-term assessment/validation process. The engine configuration studied was chosen to approximate existing rotary engine flow visualization and hot firing test rigs. Typical results include: (1) pressure and temperature histories, (2) torque generated by the nonuniform pressure distribution within the chamber, (3) energy release rates, and (4) various flow-related phenomena. These are discussed and compared with other predictions reported in the literature. The adequacy or need for improvement in the spray/combustion models and the need for incorporating an appropriate turbulence model are also discussed.
Large-scale three-dimensional geothermal reservoir simulation on small computer systems
Antunez, E.; Moridis, G.; Pruess, K.
1995-05-01
The performance of TOUGH2, Lawrence Berkeley Laboratory`s general purpose simulator for mass and heat flow and transport enhanced with the addition of a set of preconditioned conjugate gradient solvers, was tested on three PCs (486-33, 486-66, Pentium-90), a MacIntosh Quadra 800, and a workstation IBM RISC 6000. A two-phase, single porosity, 3-D geothermal reservoir model with 1,411 irregular grid blocks, with production from and injection into the reservoir was used as the test model. The code modifications to TOUGH2 and its setup in each machine environment are described. Computational work per time step and CPU time requirements are reported for each of the machines used. It is concluded that the current PCs provide the best price/performance platform for running large-scale geothermal field simulations that just a few years ago could only be executed on mainframe computers and high-end workstations.
Shemonski, Nathan D.; Ahn, Shawn S.; Liu, Yuan-Zhi; South, Fredrick A.; Carney, P. Scott; Boppart, Stephen A.
2014-01-01
Over the years, many computed optical interferometric techniques have been developed to perform high-resolution volumetric tomography. By utilizing the phase and amplitude information provided with interferometric detection, post-acquisition corrections for defocus and optical aberrations can be performed. The introduction of the phase, though, can dramatically increase the sensitivity to motion (most prominently along the optical axis). In this paper, we present two algorithms which, together, can correct for motion in all three dimensions with enough accuracy for defocus and aberration correction in computed optical interferometric tomography. The first algorithm utilizes phase differences within the acquired data to correct for motion along the optical axis. The second algorithm utilizes the addition of a speckle tracking system using temporally- and spatially-coherent illumination to measure motion orthogonal to the optical axis. The use of coherent illumination allows for high-contrast speckle patterns even when imaging apparently uniform samples or when highly aberrated beams cannot be avoided. PMID:25574426
A three-dimensional grid generation method for gas-turbine combustor flow computations
NASA Astrophysics Data System (ADS)
Shyy, Wei; Braaten, Mark E.; Sober, Janet S.
1987-02-01
A special-purpose code suitable for generating a curvilinear nonorthogonal grid system for gas-turbine combustor flow computations has been produced. The code is capable of handling an arbitrary number of dilution holes with any radii as well as film-cooling slots on the top and bottom surfaces. A zonal approach has been developed to handle the fast length scale variations imposed by the geometric constraints and to minimize the overall computational efforts needed to generate the grids. The code combines partial differential equation and algebraic interpolation methods to generate the grid system. The salient features of the grid characteristics are discussed. Also included are sample results of a 3-D turbulent combusting flow field calculated on the grid system produced by this methodology.
Manual of phosphoric acid fuel cell stack three-dimensional model and computer program
NASA Technical Reports Server (NTRS)
Lu, C. Y.; Alkasab, K. A.
1984-01-01
A detailed distributed mathematical model of phosphoric acid fuel cell stack have been developed, with the FORTRAN computer program, for analyzing the temperature distribution in the stack and the associated current density distribution on the cell plates. Energy, mass, and electrochemical analyses in the stack were combined to develop the model. Several reasonable assumptions were made to solve this mathematical model by means of the finite differences numerical method.
NASA Astrophysics Data System (ADS)
Huang, YuSheng; Xia, Jun; Yin, HanChun
2009-11-01
Integral imaging is a promising technique for both 3-D scene capturing and reconstruction. Recently, computational simulation has been used to generate the free view of reconstructed scenes without optical devices, which can easily overcome image quality degradation due to the physical limitations of optical devices. In the reconstruction process of integral imaging, current researches focus on the pinhole array model which regards lenslet array as pinhole array for simplicity. But in fact, the optical characteristics of the lenslet such as the focal length, the aperture size of the lenslet, and so on, have significant impact on the reconstructed 3-D scene. In this paper, we proposed a lenslet array model in computational integral imaging. The elemental images were picked up by using a well developed computer graphics programming library OpenGL. And then 3-D scene was reconstructed by an ideal diffraction-limited integral imaging model which taken into account of the effect of the focal length and the aperture size. We presented some simulations and evaluated the image quality by the peak-to-peak signal-to-noise ratio (PSNR). Experimental results show that the proposed lenslet array model increase the depth of field.
Computation of the eddy-current modes of three-dimensional conducting bodies
NASA Astrophysics Data System (ADS)
Gabbay, Jonathan E.; Scott, Waymond R.
2016-05-01
Low-frequency electromagnetic induction (EMI) sensors are commonly used in subsurface detection applications because of their efficacy at detecting even small fragments of metal when they are buried near the surface. This efficacy can become a shortcoming when the detector is expected to locate specific classes of targets that are buried among metallic clutter. For these applications, broadband EMI sensors have shown considerable promise at being able to detect, classify and locate targets such as land mines, and discriminate between them and the clutter with low false-alarm rates. In such cases, where differentiating targets from clutter is a significant obstacle, detection strategies based on the discrete spectrum of relaxation frequencies (DSRF) have been shown to be highly effective. For such purposes, a dictionary of DSRF of targets of interest must be computed a priori. Several classes of targets such as sphere and rings have DSRF that can be derived analytically, however, in general, the DSRF must be computed numerically. Previously, numerical strategies have been presented for thin conducting shells and rotationaly symmetric targets. In this paper, we will present a strategy to compute the DSRF of arbitrary conducting targets using a null space free Jacobi Davidson iteration (NFJD).
Level set discrete element method for three-dimensional computations with triaxial case study
NASA Astrophysics Data System (ADS)
Kawamoto, Reid; Andò, Edward; Viggiani, Gioacchino; Andrade, José E.
2016-06-01
In this paper, we outline the level set discrete element method (LS-DEM) which is a discrete element method variant able to simulate systems of particles with arbitrary shape using level set functions as a geometric basis. This unique formulation allows seamless interfacing with level set-based characterization methods as well as computational ease in contact calculations. We then apply LS-DEM to simulate two virtual triaxial specimens generated from XRCT images of experiments and demonstrate LS-DEM's ability to quantitatively capture and predict stress-strain and volume-strain behavior observed in the experiments.
NASA Astrophysics Data System (ADS)
Aryeh, F.
1982-01-01
Three interactive software systems dealing with the computerized definition, storage and handling of aircraft geometric shapes and entities in a multidisciplinary design environment are presented. The systems are operated in an interactive fashion via use of low cost graphic display terminals driven by a remote computer in a time sharing mode. GEODEF is a system for interactive definition of complex aircraft surfaces, GEOBASE is a system for interrogation and manipulation of a computerized aircraft geometry data base, and DOG is a 3-D detailed structural and mechanical part definition system.
Steady and unsteady three-dimensional transonic flow computations by integral equation method
NASA Technical Reports Server (NTRS)
Hu, Hong
1994-01-01
This is the final technical report of the research performed under the grant: NAG1-1170, from the National Aeronautics and Space Administration. The report consists of three parts. The first part presents the work on unsteady flows around a zero-thickness wing. The second part presents the work on steady flows around non-zero thickness wings. The third part presents the massively parallel processing implementation and performance analysis of integral equation computations. At the end of the report, publications resulting from this grant are listed and attached.
TEMPEST: A computer code for three-dimensional analysis of transient fluid dynamics
Fort, J.A.
1995-06-01
TEMPEST (Transient Energy Momentum and Pressure Equations Solutions in Three dimensions) is a powerful tool for solving engineering problems in nuclear energy, waste processing, chemical processing, and environmental restoration because it analyzes and illustrates 3-D time-dependent computational fluid dynamics and heat transfer analysis. It is a family of codes with two primary versions, a N- Version (available to public) and a T-Version (not currently available to public). This handout discusses its capabilities, applications, numerical algorithms, development status, and availability and assistance.
GPU-accelerated model for fast, three-dimensional fluid-structure interaction computations.
Nita, Cosmin; Itu, Lucian; Mihalef, Viorel; Sharma, Puneet; Rapaka, Saikiran
2015-08-01
In this paper we introduce a methodology for performing one-way Fluid-Structure interaction (FSI), i.e. where the motion of the wall boundaries is imposed. We use a Graphics Processing Unit (GPU) accelerated Lattice-Boltzmann Method (LBM) implementation and present an efficient workflow for embedding the moving geometry, given as a set of polygonal meshes, in the LBM computation. The proposed method is first validated in a synthetic experiment: a vessel which is periodically expanding and contracting. Next, the evaluation focuses on the 3D Peristaltic flow problem: a fluid flows inside a flexible tube, where a periodic wave-like deformation produces a fluid motion along the centerline of the tube. Different geometry configurations are used and results are compared against previously published solutions. The efficient approach leads to an average execution time of approx. one hour per computation, whereas 50% of it is required for the geometry update operations. Finally, we also analyse the effect of changing the Reynolds number on the flow streamlines: the flow regime is significantly affected by the Reynolds number. PMID:26736424
NASA Technical Reports Server (NTRS)
Weed, Richard Allen; Sankar, L. N.
1994-01-01
An increasing amount of research activity in computational fluid dynamics has been devoted to the development of efficient algorithms for parallel computing systems. The increasing performance to price ratio of engineering workstations has led to research to development procedures for implementing a parallel computing system composed of distributed workstations. This thesis proposal outlines an ongoing research program to develop efficient strategies for performing three-dimensional flow analysis on distributed computing systems. The PVM parallel programming interface was used to modify an existing three-dimensional flow solver, the TEAM code developed by Lockheed for the Air Force, to function as a parallel flow solver on clusters of workstations. Steady flow solutions were generated for three different wing and body geometries to validate the code and evaluate code performance. The proposed research will extend the parallel code development to determine the most efficient strategies for unsteady flow simulations.
Analysis of rotary engine combustion processes based on unsteady, three-dimensional computations
NASA Technical Reports Server (NTRS)
Raju, M. S.; Willis, E. A.
1989-01-01
A new computer code was developed for predicting the turbulent, and chemically reacting flows with sprays occurring inside of a stratified charge rotary engine. The solution procedure is based on an Eulerian Lagrangian approach where the unsteady, 3-D Navier-Stokes equations for a perfect gas mixture with variable properties are solved in generalized, Eulerian coordinates on a moving grid by making use of an implicit finite volume, Steger-Warming flux vector splitting scheme, and the liquid phase equations are solved in Lagrangian coordinates. Both the details of the numerical algorithm and the finite difference predictions of the combustor flow field during the opening of exhaust and/or intake, and also during fuel vaporization and combustion, are presented.
Research on techniques for computer three-dimensional simulation of satellites and night sky
NASA Astrophysics Data System (ADS)
Yan, Guangwei; Hu, Haitao
2007-11-01
To study space attack-defense technology, a simulation of satellites is needed. We design and implement a 3d simulating system of satellites. The satellites are rendered under the Night sky background. The system structure is as follows: one computer is used to simulate the orbital of satellites, the other computers are used to render 3d simulation scene. To get a realistic effect, a three-channel multi-projector display system is constructed. We use MultiGen Creator to construct satellite and star models. We use MultiGen Distributed Vega to render the three-channel scene. There are one master and three slaves. The master controls the three slaves to render three channels separately. To get satellites' positions and attitudes, the master communicates with the satellite orbit simulator based on TCP/IP protocol. Then it calculates the observer's position, the satellites' position, the moon's and the sun's position and transmits the data to the slaves. To get a smooth orbit of target satellites, an orbit prediction method is used. Because the target satellite data packets and the attack satellite data packets cannot keep synchronization in the network, a target satellite dithering phenomenon will occur when the scene is rendered. To resolve this problem, an anti-dithering algorithm is designed. To render Night sky background, a file which stores stars' position and brightness data is used. According to the brightness of each star, the stars are classified into different magnitude. The star model is scaled according to the magnitude. All the stars are distributed on a celestial sphere. Experiments show, the whole system can run correctly, and the frame rate can reach 30Hz. The system can be used in a space attack-defense simulation field.
Aoyagi, Hidekazu; Tsuchikawa, Kohzo; Iwasaki, Shin-ichi
2010-02-01
The purpose of this study was to demonstrate a micro-computed tomography (CT) method for observations of the mouse embryo. At 13.0 days post-coitum, mouse embryos were fixed in 4% paraformaldehyde for 24 h and stained en bloc by osmium tetroxide overnight. The embryos were then embedded in paraffin using standard methods for 24 h. Specimens were analyzed by micro-CT and image processing was performed. Organs containing nervous and blood systems could be viewed as a result of different osmium-staining densities. The trigeminal ganglion was imaged using three-dimensional techniques. Observation of the embryo was possible by micro-CT with osmium tetroxide staining. PMID:20155504
Sha, W.T.; Lin, E.I.H.; Schmitt, R.C.; Liu, K.V.; Hull, J.R.; Oras, J.J. Jr.; Domanus, H.M.
1980-11-01
COMMIX-SA-1 is a three-dimensional, transient, single-phase, compressible-flow, component computer program for thermohydrodynamic analysis. It was developed for solar applications in general, and for analysis of thermocline storage tanks in particular. The conservation equations (in cylindrical coordinates) for mass, momentum, and energy are solved as an initial-boundary-value problem. The detailed numerical-solution procedure based on a modified ICE (Implicit Continuous-Fluid Eulerian) technique is described. A method for treating the singularity problem arising at the origin of a cylindrical-coordinate system is presented. In addition, the thermal interactions between fluid and structures (tank walls, baffles, etc.) are explicitly accounted for. Finally, the COMMIX-SA-1 code structure is delineated, and an input description and sample problems are presented.
NASA Technical Reports Server (NTRS)
Farrell, C. A.
1982-01-01
A fast, reliable computer code is described for calculating the flow field about a cascade of arbitrary two dimensional airfoils. The method approximates the three dimensional flow in a turbomachinery blade row by correcting for stream tube convergence and radius change in the throughflow direction. A fully conservative solution of the full potential equation is combined with the finite volume technique on a body-fitted periodic mesh, with an artificial density imposed in the transonic region to insure stability and the capture of shock waves. The instructions required to set up and use the code are included. The name of the code is QSONIC. A numerical example is also given to illustrate the output of the program.
Halicioglu, Koray; Celikoglu, Mevlut; Buyuk, Suleyman Kutalmis; Sekerci, Ahmet Ercan; Ucar, Faruk Izzet; Yavuz, Ibrahim
2014-01-01
Objectives: The aim was to investigate mandibular third molar (3M)'s maturation in the crossbite and normal sides by two- and three-dimensional analyses using cone beam computed tomography (CBCT). Materials and Methods: A retrospective study was performed using CBCT of 25 patients (16 females and 9 males; mean age: 16.8 ± 2.9 years) with unilateral posterior crossbite. The formation stages and the volume of the mandibular 3Ms were evaluated by means of CBCT data of the patients without knowing the crossbite side of the patients. Results: Statistically no significant differences were found in the development of the 3Ms between the crossbite and the control sides, whereas the volume of 3M was found to be less in the crossbite side than in the normal side (P = 0.021). Conclusions: A volume of 3M was found to be less in the crossbite side than in the normal side. PMID:25202221
Kim, Yong Hyun; Kang, Seok Joo
2016-01-01
Background We conducted this study to analyze the values of the key cephalometric angular measurements of the mandible using 3-dimensional (3D) computed tomography scans. Methods In the 106 enrolled patients, a 3D cephalometric analysis was performed to measure the angular variables of the mandible. These values were compared between the two sides and between the two sexes. Results The frontal measurements revealed that the mandibular body curve angle was larger on the left (Lt) side (right [Rt], 141.24±7.54; Lt, 142.68±6.94; P=0.002) and the gonial angle was larger on the right side (Rt, 134.37±8.44; Lt, 131.54±7.14; P<0.001). The sagittal measurements showed that the gonial angle was larger on the right side (Rt, 134.37±8.44; Lt, 131.54±7.14; P>0.05). Further, the transverse measurements revealed that the mandibular body curve angle was larger on the right side (Rt, 140.28±7.05; Lt, 137.56±6.23; P<0.001). Conclusions These results provide an average of the mandibular angular measurements for the Korean population, establishing a standard for determining surgical patient groups and outcome evaluations in the field of mandible contour surgery. PMID:26848443
Henning, Alyssa L.; Jiang, Michael X.; Yalcin, Huseyin C.; Butcher, Jonathan T.
2013-01-01
Many clinically relevant congenital malformations arise during mid to late embryonic stages. This period is challenging to image quantitatively in live embryos, necessitating the use of multiple specimens with increased experimental variability. Here we establish X-ray and blood-pool computed tomography (CT) contrast agent toxicity and teratogenesis thresholds for 3D Micro-CT imaging of live avian embryos. Day 4 chick embryos micro-injected with Visipaque™ (VP) developed for an additional 6 days without defect. X-ray radiation up to 798 mGy was nontoxic. Peak average contrast of 1,060 HU occurred within 1 hr of imaging at 50 μm resolution. VP-enhanced contrast persisted past 24 hr with delayed accumulation in the allantois. Regional volumes of VP-injected embryos were statistically identical to those of fixed embryos perfused with osmium tetroxide. We further quantified longitudinal volumetric morphogenesis of the allantois over 30 hr. These results demonstrate the safety and efficacy of contrast enhanced quantitative micro-CT imaging for live embryos. PMID:21761480
Three-dimensional segmentation of the tumor mass in computed tomographic images of neuroblastoma
NASA Astrophysics Data System (ADS)
Deglint, Hanford J.; Rangayyan, Rangaraj M.; Boag, Graham S.
2004-05-01
Tumor definition and diagnosis require the analysis of the spatial distribution and Hounsfield unit (HU) values of voxels in computed tomography (CT) images, coupled with a knowledge of normal anatomy. Segmentation of the tumor in neuroblastoma is complicated by the fact that the mass is almost always heterogeneous in nature; furthermore, viable tumor, necrosis, fibrosis, and normal tissue are often intermixed. Rather than attempt to separate these tissue types into distinct regions, we propose to explore methods to delineate the normal structures expected in abdominal CT images, remove them from further consideration, and examine the remaining parts of the images for the tumor mass. We explore the use of fuzzy connectivity for this purpose. Expert knowledge provided by the radiologist in the form of the expected structures and their shapes, HU values, and radiological characteristics are also incorporated in the segmentation algorithm. Segmentation and analysis of the tissue composition of the tumor can assist in quantitative assessment of the response to chemotherapy and in the planning of delayed surgery for resection of the tumor. The performance of the algorithm is evaluated using cases acquired from the Alberta Children's Hospital.
Lattice-Boltzmann simulations of three-dimensional fluid flow on a desktop computer.
Brewster, Jeffrey D
2007-04-01
The lattice-Boltzmann (LB) method is a cellular automaton approach to simulating fluid flow with many advantages over conventional methods based on the Navier-Stokes equations. It is conceptually simple, amenable to a wide array of boundary conditions, and can be adapted to handle thermal, density, miscibility, and other effects. The LB approach has been used to model a number of fluid systems of interest to analytical chemists, including chromatography columns, micromixers, and electroosmotic pumps. However, widespread use of this tool has been limited, in part because virtually all large-scale 3D simulations in the literature have been executed on supercomputers. This work demonstrates that such simulations can be executed in reasonable periods of time (hours) on a desktop computer using a cross-platform software package that is easy to learn and use. This package incorporates several improvements that enhance the utility of the LB approach, including an algorithm for speeding common calculations by 2 orders of magnitude and a scheme for handling convection-diffusion equations of interest in electrochemical and surface reaction studies. PMID:17319648
Three-dimensional computer-aided human factors engineering analysis of a grafting robot.
Chiu, Y C; Chen, S; Wu, G J; Lin, Y H
2012-07-01
The objective of this research was to conduct a human factors engineering analysis of a grafting robot design using computer-aided 3D simulation technology. A prototype tubing-type grafting robot for fruits and vegetables was the subject of a series of case studies. To facilitate the incorporation of human models into the operating environment of the grafting robot, I-DEAS graphic software was applied to establish individual models of the grafting robot in line with Jack ergonomic analysis. Six human models (95th percentile, 50th percentile, and 5th percentile by height for both males and females) were employed to simulate the operating conditions and working postures in a real operating environment. The lower back and upper limb stresses of the operators were analyzed using the lower back analysis (LBA) and rapid upper limb assessment (RULA) functions in Jack. The experimental results showed that if a leg space is introduced under the robot, the operator can sit closer to the robot, which reduces the operator's level of lower back and upper limbs stress. The proper environmental layout for Taiwanese operators for minimum levels of lower back and upper limb stress are to set the grafting operation at 23.2 cm away from the operator at a height of 85 cm and with 45 cm between the rootstock and scion units. PMID:22900432
NASA Astrophysics Data System (ADS)
Leader, J. Ken, III; Boston, J. Robert; Rudy, Thomas E.; Greco, Carol M.; Zaki, Hussein S.
2001-05-01
Jaw motion has been used to diagnose jaw pain patients, and we have developed a 3D computer animation technique to study jaw motion. A customized dental clutch was worn during motion, and its consistent and rigid placement was a concern. The experimental protocol involved mandibular movements (vertical opening) and MR imaging. The clutch contained three motion markers used to collect kinematic data and four MR markers used as fiducial markers in the MR images. Fiducial marker misplacement was mimicked by analytically perturbing the position of the MR markers +/- 2, +/- 4, and +/- 6 degrees in the three anatomical planes. The percent difference between the original and perturbed MR marker position was calculated for kinematic parameters. The maximum difference across all perturbations for axial rotation, coronal rotation, sagittal rotation, axial translation, coronal translation, and sagittal translation were 176.85%, 191.84%, 0.64%, 9.76%, 80.75%, and 8.30%, respectively, for perturbing all MR markers, and 86.47%, 93.44%, 0.23%, 7.08%, 42.64%, and 13.64%, respectively, for perturbing one MR marker. The parameters representing movement in the sagittal plane, the dominant plane in vertical opening, were determined to be reasonably robust, while secondary movements in the axial and coronal planes were not considered robust.
NASA Technical Reports Server (NTRS)
Cho, Soo-Yong; Greber, Isaac
1994-01-01
Numerical investigations on a diffusing S-duct with/without vortex generators and a straight duct with vortex generators are presented. The investigation consists of solving the full three-dimensional unsteady compressible mass averaged Navier-Stokes equations. An implicit finite volume lower-upper time marching code (RPLUS3D) has been employed and modified. A three-dimensional Baldwin-Lomax turbulence model has been modified in conjunction with the flow physics. A model for the analysis of vortex generators in a fully viscous subsonic internal flow is evaluated. A vortical structure for modeling the shed vortex is used as a source term in the computation domain. The injected vortex paths in the straight duct are compared with the analysis by two kinds of prediction models. The flow structure by the vortex generators are investigated along the duct. Computed results of the flow in a circular diffusing S-duct provide an understanding of the flow structure within a typical engine inlet system. These are compared with the experimental wall static-pressure, static- and total-pressure field, and secondary velocity profiles. Additionally, boundary layer thickness, skin friction values, and velocity profiles in wall coordinates are presented. In order to investigate the effect of vortex generators, various vortex strengths are examined in this study. The total-pressure recovery and distortion coefficients are obtained at the exit of the S-duct. The numerical results clearly depict the interaction between the low velocity flow by the flow separation and the injected vortices.
WASINPONGWANICH, Kanthika; PAHOLPAK, Permsak; TUAMSUK, Panya; SIRICHATIVAPEE, Winai; WISANUYOTIN, Taweechok; KOSUWON, Weerachai; JEERAVIPOOLVARN, Polasak
2014-01-01
Malpositioning of cervical screws risks neurovascular injury. A cervical screw fixation system can provide proper rigidity, alignment correction, and high rates of fusion afforded by high pullout biomechanical strength. The objective is to assess the dimensions and axis of the C3–C7 cervical pedicles. A 1-mm slice thickness computed tomography (CT) scan of the cervical spine of 30 patients (15 males, 15 females) were analyzed and reconstructed in three-dimensions using Mimics® 10.01 software. We measured pedicle axis length (PAL), pedicle and lateral mass length (PL-LM), pedicle length (PL), outer pedicle width (OPW), and pedicle transverse angle (PTA) from the axial image and outer pedicle height (OPH) and pedicle sagittal angle (PSA) from the sagittal image. The OPH and OPW at all subaxial cervical spines were suitable for insertion of 3.5 mm cervical pedicle screws. PSA was directed cranially at C3 to C5 (13.84, 7.09, and 2.71) and directed caudally at C6 and C7 (–4.55, –6.94). PTA was greatest at C5 and smallest at C7. The respective difference between the left and right side for nearly all parameters was not statistically significant (except for C6 PL and C7 OPH). Females had a significantly smaller OPH and OPW than males at nearly all levels. The PTA was not significantly different between the sexes. Cervical pedicle screw fixation in the Thai population can be safely performed and guidelines for insertion at each vertebra documented. Appropriate preoperative planning is necessary to achieve safe and accurate placement of the screws. PMID:25169140
Three-dimensional electromagnetic modeling and inversion on massively parallel computers
Newman, G.A.; Alumbaugh, D.L.
1996-03-01
This report has demonstrated techniques that can be used to construct solutions to the 3-D electromagnetic inverse problem using full wave equation modeling. To this point great progress has been made in developing an inverse solution using the method of conjugate gradients which employs a 3-D finite difference solver to construct model sensitivities and predicted data. The forward modeling code has been developed to incorporate absorbing boundary conditions for high frequency solutions (radar), as well as complex electrical properties, including electrical conductivity, dielectric permittivity and magnetic permeability. In addition both forward and inverse codes have been ported to a massively parallel computer architecture which allows for more realistic solutions that can be achieved with serial machines. While the inversion code has been demonstrated on field data collected at the Richmond field site, techniques for appraising the quality of the reconstructions still need to be developed. Here it is suggested that rather than employing direct matrix inversion to construct the model covariance matrix which would be impossible because of the size of the problem, one can linearize about the 3-D model achieved in the inverse and use Monte-Carlo simulations to construct it. Using these appraisal and construction tools, it is now necessary to demonstrate 3-D inversion for a variety of EM data sets that span the frequency range from induction sounding to radar: below 100 kHz to 100 MHz. Appraised 3-D images of the earth`s electrical properties can provide researchers opportunities to infer the flow paths, flow rates and perhaps the chemistry of fluids in geologic mediums. It also offers a means to study the frequency dependence behavior of the properties in situ. This is of significant relevance to the Department of Energy, paramount to characterizing and monitoring of environmental waste sites and oil and gas exploration.
NASA Technical Reports Server (NTRS)
Shrewsbury, George D.; Vadyak, Joseph; Schuster, David M.; Smith, Marilyn J.
1989-01-01
A computer analysis was developed for calculating steady (or unsteady) three-dimensional aircraft component flow fields. This algorithm, called ENS3D, can compute the flow field for the following configurations: diffuser duct/thrust nozzle, isolated wing, isolated fuselage, wing/fuselage with or without integrated inlet and exhaust, nacelle/inlet, nacelle (fuselage) afterbody/exhaust jet, complete transport engine installation, and multicomponent configurations using zonal grid generation technique. Solutions can be obtained for subsonic, transonic, or hypersonic freestream speeds. The algorithm can solve either the Euler equations for inviscid flow, the thin shear layer Navier-Stokes equations for viscous flow, or the full Navier-Stokes equations for viscous flow. The flow field solution is determined on a body-fitted computational grid. A fully-implicit alternating direction implicit method is employed for the solution of the finite difference equations. For viscous computations, either a two layer eddy-viscosity turbulence model or the k-epsilon two equation transport model can be used to achieve mathematical closure.
Bakhshaee, Hani; Moro, Christina; Kost, Karen; Mongeau, Luc
2013-01-01
Summary Three-dimensional (3D) computer models of the human larynx are useful tools for research and for eventual clinical applications. Recently, computed tomography (CT) scanning and magnetic resonance imaging (MRI) have been used to recreate realistic models of human larynx. In the present study, CT images were used to create computer models of vocal folds, vocal tract, and laryngeal cartilages, and the procedure to create solid models are explained in details. Vocal fold and vocal tract 3D models of healthy and postsurgery larynges during phonation and respiration were created and morphometric parameters were quantified. The laryngeal framework of eight patients was also reconstructed from CT scan images. For each cartilage, morphometric landmarks were measured on the basis of their importance for biomechanical modeling. A quantitative comparison was made between measured values from the reconstructions and those from human excised larynges in literature. The good agreement between these measurements supports the accuracy of CT scan-based 3D models. Generic standard models of the laryngeal framework were created using known features in modeling softwares. They were created based on the morphometric landmark dimensions previously defined, preserving all biomechanically important dimensions. These models are accessible, subject independent, easy to use for computational simulations, and make the comparisons between different studies possible. PMID:24119643
Naghibi, Saeed; Seifirad, Sirous; Adami Dehkordi, Mahboobeh; Einolghozati, Sasan; Ghaffarian Eidgahi Moghadam, Nafiseh; Akhavan Rezayat, Amir; Seifirad, Soroush
2016-01-01
Background: Chronic otitis media (COM) can be treated with tympanoplasty with or without mastoidectomy. In patients who have undergone middle ear surgery, three-dimensional spiral computed tomography (CT) scan plays an important role in optimizing surgical planning. Objectives: This study was performed to compare the findings of three-dimensional reconstructed spiral and conventional CT scan of ossicular chain study in patients with COM. Patients and Methods: Fifty patients enrolled in the study underwent plane and three dimensional CT scan (PHILIPS-MX 8000). Ossicles changes, mastoid cavity, tympanic cavity, and presence of cholesteatoma were evaluated. Results of the two methods were then compared and interpreted by a radiologist, recorded in questionnaires, and analyzed. Logistic regression test and Kappa coefficient of agreement were used for statistical analyses. Results: Sixty two ears with COM were found in physical examination. A significant difference was observed between the findings of the two methods in ossicle erosion (11.3% in conventional CT vs. 37.1% in spiral CT, P = 0.0001), decrease of mastoid air cells (82.3% in conventional CT vs. 93.5% in spiral CT, P = 0.001), and tympanic cavity opacity (12.9% in conventional CT vs. 40.3% in spiral CT, P=0.0001). No significant difference was observed between the findings of the two methods in ossicle destruction (6.5% conventional CT vs. 56.4% in spiral CT, P = 0.125), and presence of cholesteatoma (3.2% in conventional CT vs. 42% in spiral CT, P = 0.172). In this study, spiral CT scan demonstrated ossicle dislocation in 9.6%, decrease of mastoid air cells in 4.8%, and decrease of volume in the tympanic cavity in 1.6%; whereas, none of these findings were reported in the patients' conventional CT scans. Conclusion: Spiral-CT scan is superior to conventional CT in the diagnosis of lesions in COM before operation. It can be used for detailed evaluation of ossicular chain in such patients. PMID:27127583
Waters, A M
2001-05-01
In an effort to increase automobile fuel efficiency as well as decrease the output of harmful greenhouse gases, the automotive industry has recently shown increased interest in cast light metals such as magnesium alloys in an effort to increase weight savings. Currently several magnesium alloys such as AZ91 and AM60B are being used in structural applications for automobiles. However, these magnesium alloys are not as well characterized as other commonly used structural metals such as aluminum. This dissertation presents a methodology to nondestructively quantify damage accumulation due to void behavior in three dimensions in die-cast magnesium AM60B tensile bars as a function of mechanical load. Computed tomography data was acquired after tensile bars were loaded up to and including failure, and analyzed to characterize void behavior as it relates to damage accumulation. Signal and image processing techniques were used along with a cluster labeling routine to nondestructively quantify damage parameters in three dimensions. Void analyses were performed including void volume distribution characterization, nearest neighbor distance calculations, shape parameters, and volumetric renderings of voids in the alloy. The processed CT data was used to generate input files for use in finite element simulations, both two- and three-dimensional. The void analyses revealed that the overwhelming source of failure in each tensile bar was a ring of porosity within each bar, possibly due to a solidification front inherent to the casting process. The measured damage parameters related to void nucleation, growth, and coalescence were shown to contribute significantly to total damage accumulation. Void volume distributions were characterized using a Weibull function, and the spatial distributions of voids were shown to be clustered. Two-dimensional finite element analyses of the tensile bars were used to fine-tune material damage models and a three-dimensional mesh of an extracted
NASA Astrophysics Data System (ADS)
Shimobaba, Tomoyoshi; Kakue, Takashi; Ito, Tomoyoshi
2014-06-01
We propose acceleration of color computer-generated holograms (CGHs) from three-dimensional (3D) scenes that are expressed as texture (RGB) and depth (D) images. These images are obtained by 3D graphics libraries and RGB-D cameras: for example, OpenGL and Kinect, respectively. We can regard them as two-dimensional (2D) cross-sectional images along the depth direction. The generation of CGHs from the 2D cross-sectional images requires multiple diffraction calculations. If we use convolution-based diffraction such as the angular spectrum method, the diffraction calculation takes a long time and requires large memory usage because the convolution diffraction calculation requires the expansion of the 2D cross-sectional images to avoid the wraparound noise. In this paper, we first describe the acceleration of the diffraction calculation using "Band-limited double-step Fresnel diffraction," which does not require the expansion. Next, we describe color CGH acceleration using color space conversion. In general, color CGHs are generated on RGB color space; however, we need to repeat the same calculation for each color component, so that the computational burden of the color CGH generation increases three-fold, compared with monochrome CGH generation. We can reduce the computational burden by using YCbCr color space because the 2D cross-sectional images on YCbCr color space can be down-sampled without the impairing of the image quality.
Zweben, S. J.; Scott, B. D.; Terry, J. L.; LaBombard, B.; Hughes, J. W.; Stotler, D. P.
2009-09-01
This paper describes quantitative comparisons between turbulence measured in the scrape-off layer (SOL) of Alcator C-Mod [S. Scott, A. Bader, M. Bakhtiari et al., Nucl. Fusion 47, S598 (2007)] and three dimensional computations using electromagnetic gyrofluid equations in a two-dimensional tokamak geometry. These comparisons were made for the outer midplane SOL for a set of inner-wall limited, near-circular Ohmic plasmas. The B field and plasma density were varied to assess gyroradius and collisionality scaling. The poloidal and radial correlation lengths in the experiment and computation agreed to within a factor of 2 and did not vary significantly with either B or density. The radial and poloidal propagation speeds and the frequency spectra and poloidal k-spectra also agreed fairly well. However, the autocorrelation times and relative Da fluctuation levels were higher in the experiment by more than a factor of 2. Possible causes for these disagreements are discussed. 2009 American Institute of Physics.
Liu, Haixia; Tan, Tao; van Zelst, Jan; Mann, Ritse; Karssemeijer, Nico; Platel, Bram
2014-07-01
We investigated the benefits of incorporating texture features into an existing computer-aided diagnosis (CAD) system for classifying benign and malignant lesions in automated three-dimensional breast ultrasound images. The existing system takes into account 11 different features, describing different lesion properties; however, it does not include texture features. In this work, we expand the system by including texture features based on local binary patterns, gray level co-occurrence matrices, and Gabor filters computed from each lesion to be diagnosed. To deal with the resulting large number of features, we proposed a combination of feature-oriented classifiers combining each group of texture features into a single likelihood, resulting in three additional features used for the final classification. The classification was performed using support vector machine classifiers, and the evaluation was done with 10-fold cross validation on a dataset containing 424 lesions (239 benign and 185 malignant lesions). We compared the classification performance of the CAD system with and without texture features. The area under the receiver operating characteristic curve increased from 0.90 to 0.91 after adding texture features ([Formula: see text]). PMID:26158036
Proteus three-dimensional Navier-Stokes computer code, version 1.0. Volume 2: User's guide
NASA Technical Reports Server (NTRS)
Towne, Charles E.; Schwab, John R.; Bui, Trong T.
1993-01-01
A computer code called Proteus 3D was developed to solve the three-dimensional, Reynolds-averaged, unsteady compressible Navier-Stokes equations in strong conservation law form. The objective in this effort was to develop a code for aerospace propulsion applications that is easy to use and easy to modify. Code readability, modularity, and documentation were emphasized. The governing equations are solved in generalized nonorthogonal body-fitted coordinates, by marching in time using a fully-coupled ADI solution procedure. The boundary conditions are treated implicitly. All terms, including the diffusion terms, are linearized using second-order Taylor series expansions. Turbulence is modeled using either an algebraic or two-equation eddy viscosity model. The thin-layer or Euler equations may also be solved. The energy equation may be eliminated by the assumption of constant total enthalpy. Explicit and implicit artificial viscosity may be used. Several time step options are available for convergence acceleration. The documentation is divided into three volumes. This User's Guide describes the program's features, the input and output, the procedure for setting up initial conditions, the computer resource requirements, the diagnostic messages that may be generated, the job control language used to run the program, and several test cases.
NASA Technical Reports Server (NTRS)
Jumper, S. J.
1982-01-01
A computer program was developed to calculate the three dimensional, steady, incompressible, inviscid, irrotational flow field at the propeller plane (propeller removed) located upstream of an arbitrary airframe geometry. The program uses a horseshoe vortex of known strength to model the wing. All other airframe surfaces are modeled by a network source panels of unknown strength which is exposed to a uniform free stream and the wing-induced velocity field. By satisfying boundary conditions on each panel (the Neumann problem), relaxed boundary conditions being used on certain panels to simulate inlet inflow, the source strengths are determined. From the known source and wing vortex strengths, the resulting velocity fields on the airframe surface and at the propeller plane are obtained. All program equations are derived in detail, and a brief description of the program structure is presented. A user's manual which fully documents the program is cited. Computer predictions of the flow on the surface of a sphere and at a propeller plane upstream of the sphere are compared with the exact mathematical solutions. Agreement is good, and correct program operation is verified.
Liu, Haixia; Tan, Tao; van Zelst, Jan; Mann, Ritse; Karssemeijer, Nico; Platel, Bram
2014-01-01
Abstract. We investigated the benefits of incorporating texture features into an existing computer-aided diagnosis (CAD) system for classifying benign and malignant lesions in automated three-dimensional breast ultrasound images. The existing system takes into account 11 different features, describing different lesion properties; however, it does not include texture features. In this work, we expand the system by including texture features based on local binary patterns, gray level co-occurrence matrices, and Gabor filters computed from each lesion to be diagnosed. To deal with the resulting large number of features, we proposed a combination of feature-oriented classifiers combining each group of texture features into a single likelihood, resulting in three additional features used for the final classification. The classification was performed using support vector machine classifiers, and the evaluation was done with 10-fold cross validation on a dataset containing 424 lesions (239 benign and 185 malignant lesions). We compared the classification performance of the CAD system with and without texture features. The area under the receiver operating characteristic curve increased from 0.90 to 0.91 after adding texture features (p<0.001). PMID:26158036
Kang, Joon Soon; Won, Man Hee; Park, Myoung Joo; Choi, Jae Hwang
2015-01-01
Purpose This study was performed to determine the usefulness of three-dimensional computed tomography (3D-CT) in measuring periacetabular osteolysis by comparing the real volume of osteolysis in revision surgery. Materials and Methods Twnety-three patients who had undergone revision surgery due to periacetabular osteolysis but not included septic osteolysis and implant loosening. The mean age of patients at the time of surgery was 55.2 years. And the mean time interval between the primary total hip arthroplasty and revision surgery was 13.3 years. We measured the polyethylene wear in plain radiographs using computer assisted vector wear analysis program, the volume of acetabular osteolytic lesions in high-resolution spiral CT scans using Rapidia 3D software version 2.8 algorithms before the revision surgery were performed. Intraoperative real osteolytic volume was calculated as the sum of the volumetric increments of the acetabular cup and impacted allo-cancellous bone volume. Results Strong correlation was found between the volume of acetabular osteolytic lesions measured on 3D-CT and intraoperative real osteolytic volume which was calculated as the sum of the volumetric increments of the acetabular cup and impacted allo-cancellous bone volume. Conclusion 3D-CT is considered a useful method for assessing and measuring the volume of periacetabular osteolysis before revision surgery.
NASA Technical Reports Server (NTRS)
Dulikravich, D. S.
1981-01-01
A fast algorithm was developed for accurately generating boundary-conforming, three-dimensional, consecutively refined computational grids applicable to arbitrary wing-body and axial turbomachinery geometries. The method is based on using an analytic function to generate two-dimensional grids on a number of coaxial axisymmetric surfaces positioned between the centerbody and the outer radial boundary. These grids are of the O-type and are characterized by quasi-orthogonality, geometric periodicity, and an adequate resolution throughout the flow field. Because the built-in nonorthogonal coordinate stretching and shearing cause the grid lines leaving the blade or wing trailing edge to end at downstream infinity, the numerical treatment of the three-dimensional trailing vortex sheets is simplified.
Cengiz, Mustafa Guerdalli, Salih; Selek, Ugur; Yildiz, Ferah; Saglam, Yuecel; Ozyar, Enis; Atahan, I. Lale
2008-02-01
Purpose: To quantify the effect of bladder volume on the dose distribution during intracavitary brachytherapy for cervical cancer. Methods and Patients: The study was performed on 10 women with cervical cancer who underwent brachytherapy treatment. After insertion of the brachytherapy applicator, the patients were transferred to the computed tomography unit. Two sets of computed tomography slices were taken, including the pelvis, one with an empty bladder and one after the bladder was filled with saline. The target and critical organs were delineated by the radiation oncologist and checked by the expert radiologist. The radiotherapy plan was run on the Plato planning system, version 14.1, to determine the dose distributions, dose-volume histograms, and maximal dose points. The doses and organ volumes were compared with the Wilcoxon signed ranks test on a personal computer using the Statistical Package for Social Sciences, version 11.0, statistical program. Results: No significant difference regarding the dose distribution and target volumes between an empty or full bladder was observed. Bladder fullness significantly affected the dose to the small intestine, rectum, and bladder. The median of maximal doses to the small intestine was significantly greater with an empty bladder (493 vs. 284 cGy). Although dosimetry revealed lower doses for larger volumes of bladder, the median maximal dose to the bladder was significantly greater with a full bladder (993 vs. 925 cGy). The rectal doses were also affected by bladder distension. The median maximal dose was significantly lower in the distended bladder (481vs. 628 cGy). Conclusions: Bladder fullness changed the dose distributions to the bladder, rectum, and small intestine. The clinical importance of these changes is not known and an increase in the use of three-dimensional brachytherapy planning will highlight the answer to this question.
NASA Astrophysics Data System (ADS)
LaFleur, Karl; Cassady, Kaitlin; Doud, Alexander; Shades, Kaleb; Rogin, Eitan; He, Bin
2013-08-01
Objective. At the balanced intersection of human and machine adaptation is found the optimally functioning brain-computer interface (BCI). In this study, we report a novel experiment of BCI controlling a robotic quadcopter in three-dimensional (3D) physical space using noninvasive scalp electroencephalogram (EEG) in human subjects. We then quantify the performance of this system using metrics suitable for asynchronous BCI. Lastly, we examine the impact that the operation of a real world device has on subjects' control in comparison to a 2D virtual cursor task. Approach. Five human subjects were trained to modulate their sensorimotor rhythms to control an AR Drone navigating a 3D physical space. Visual feedback was provided via a forward facing camera on the hull of the drone. Main results. Individual subjects were able to accurately acquire up to 90.5% of all valid targets presented while travelling at an average straight-line speed of 0.69 m s-1. Significance. Freely exploring and interacting with the world around us is a crucial element of autonomy that is lost in the context of neurodegenerative disease. Brain-computer interfaces are systems that aim to restore or enhance a user's ability to interact with the environment via a computer and through the use of only thought. We demonstrate for the first time the ability to control a flying robot in 3D physical space using noninvasive scalp recorded EEG in humans. Our work indicates the potential of noninvasive EEG-based BCI systems for accomplish complex control in 3D physical space. The present study may serve as a framework for the investigation of multidimensional noninvasive BCI control in a physical environment using telepresence robotics.
Bormann, Therese; Schulz, Georg; Deyhle, Hans; Beckmann, Felix; de Wild, Michael; Küffer, Jürg; Münch, Christoph; Hoffmann, Waldemar; Müller, Bert
2014-02-01
Appropriate mechanical stimulation of bony tissue enhances osseointegration of load-bearing implants. Uniaxial compression of porous implants locally results in tensile and compressive strains. Their experimental determination is the objective of this study. Selective laser melting is applied to produce open-porous NiTi scaffolds of cubic units. To measure displacement and strain fields within the compressed scaffold, the authors took advantage of synchrotron radiation-based micro computed tomography during temperature increase and non-rigid three-dimensional data registration. Uniaxial scaffold compression of 6% led to local compressive and tensile strains of up to 15%. The experiments validate modeling by means of the finite element method. Increasing the temperature during the tomography experiment from 15 to 37°C at a rate of 4 K h(-1), one can locally identify the phase transition from martensite to austenite. It starts at ≈ 24°C on the scaffolds bottom, proceeds up towards the top and terminates at ≈ 34°C on the periphery of the scaffold. The results allow not only design optimization of the scaffold architecture, but also estimation of maximal displacements before cracks are initiated and of optimized mechanical stimuli around porous metallic load-bearing implants within the physiological temperature range. PMID:24257506
NASA Astrophysics Data System (ADS)
Perrot, Camille; Olny, Xavier; Panneton, Raymond; Bouchard, Richard
2001-05-01
Acoustic dissipation in porous media is mainly due to viscous and thermal mechanisms that occur in the pores of the microstructure. The purpose of this study is the determination of the macroscopic dynamic acoustic bulk modulus and thermal permeability of real foams from a local scale approach. To achieve this goal, two distinct steps are followed. First, the local geometry of a real foam is obtained using computed microtomography (μCT), then a periodic and regularly paving space tetrakaidecahedron cell is identified from the microstructure. Second, the heat equation is solved for the geometrical model. The paper provides a three-dimensional application of the efficient simulation technique of Brownian motion proposed by Torquato et al. for steady state diffusion-controlled problems [Appl. Phys. Lett. 55, 1847-1849 (1989)] and adapted by Lafarge [Poromechanics II, 708 (2002)] in a bi-dimensional case. The influence of the model's microstructural details (anisotropy, and struts junction and cross-section) on the macroscopic properties are studied. The predictions of the macroscopic properties using this local scale approach are then compared to experimental measurements.
Ghatwary, Tamer M. H.; Patterson, Benjamin O.; Karthikesalingam, Alan; Hinchliffe, Robert J.; Loftus, Ian M.; Morgan, Robert; Thompson, Matt M.; Holt, Peter J. E.
2013-02-15
The morphology of infrarenal abdominal aortic aneurysms (AAAs) directly influences the perioperative outcome and long-term durability of endovascular aneurysm repair. A variety of methods have been proposed for the characterization of AAA morphology using reconstructed three-dimensional (3D) computed tomography (CT) images. At present, there is lack of consensus as to which of these methods is most applicable to clinical practice or research. The purpose of this review was to evaluate existing protocols that used 3D CT images in the assessment of various aspects of AAA morphology. An electronic search was performed, from January 1996 to the end of October 2010, using the Embase and Medline databases. The literature review conformed to PRISMA statement standards. The literature search identified 604 articles, of which 31 studies met inclusion criteria. Only 15 of 31 studies objectively assessed reproducibility. Existing published protocols were insufficient to define a single evidence-based methodology for preoperative assessment of AAA morphology. Further development and expert consensus are required to establish a standardized and validated protocol to determine precisely how morphology relates to outcomes after endovascular aneurysm repair.
Feshchenko, R M; Popov, A V
2013-11-01
We report an exact transparent boundary condition (TBC) on the surface of a rectangular cuboid for the three-dimensional (3D) time-dependent Schrödinger equation. It is obtained as a generalization of the well-known TBC for the 1D Schrödinger equation and of the exact TBC in the rectangular domain for the 3D parabolic wave equation, which we reported earlier. Like all other TBCs, it is nonlocal in time domain and relates the boundary transverse derivative of the wave function at any given time to the boundary values of the same wave function at all preceding times. We develop a discretization of this boundary condition for the implicit Crank-Nicolson finite difference scheme. Several numerical experiments demonstrate evolution of the wave function in free space as well as propagation through a number of 3D spherically symmetrical and asymmetrical barriers, and, finally, scattering off an asymmetrical 3D potential. The proposed boundary condition is simple and robust, and can be useful in computational quantum mechanics when an accurate numerical solution of the 3D Schrödinger equation is required. PMID:24329380
Computational analysis of a three-dimensional High-Velocity Oxygen-Fuel (HVOF) Thermal Spray torch
Hassan, B.; Lopez, A.R.; Oberkampf, W.L.
1995-07-01
An analysis of a High-Velocity Oxygen-Fuel Thermal Spray torch is presented using computational fluid dynamics (CFD). Three-dimensional CFD results are presented for a curved aircap used for coating interior surfaces such as engine cylinder bores. The device analyzed is similar to the Metco Diamond Jet Rotating Wire torch, but wire feed is not simulated. To the authors` knowledge, these are the first published 3-D results of a thermal spray device. The feed gases are injected through an axisymmetric nozzle into the curved aircap. Argon is injected through the center of the nozzle. Pre-mixed propylene and oxygen are introduced from an annulus in the nozzle, while cooling air is injected between the nozzle and the interior wall of the aircap. The combustion process is modeled assuming instantaneous chemistry. A standard, two-equation, K-{var_epsilon} turbulence model is employed for the turbulent flow field. An implicit, iterative, finite volume numerical technique is used to solve the coupled conservation of mass, momentum, and energy equations for the gas in a sequential manner. Flow fields inside and outside the aircap are presented and discussed.
Kauppinen, P K; Hyttinen, J A; Malmivuo, J A
1998-01-01
Impedance cardiography (ICG) offers a safe, noninvasive, and inexpensive method to track stroke volume estimates over long periods of time. Several modified ICG measurement configurations have been suggested where for convenience or improved performance the standard band electrodes are replaced with electrocardiogram electrodes. This report assesses the sensitivity of the conventional and three modified ICG methods in detecting regional conductivity changes in the simulated human thorax. The theoretical analyses of the measurement sensitivity employ the reciprocity theorem and the lead field theory with a highly detailed, anatomically accurate, three-dimensional computer thorax model. This model is based on the finite-difference element method and the U.S. National Library of Medicine's Visible Human Man anatomy data. The results obtained indicate that the conventional four-band ICG is not specifically sensitive to detect conductivity changes in the region of the heart, aortas, and lungs. Analyzed modified electrode configurations do not reproduce exactly the measurement sensitivity distribution of the conventional four-band ICG. Thus, although the signals measured with modified spot arrangements may appear similar to the four-band configuration, the distribution of the signal origin may not be the same. Changing from band to spot electrodes does not overcome the methodological problems associated with ICG. PMID:9662161
Proteus three-dimensional Navier-Stokes computer code, version 1.0. Volume 1: Analysis description
NASA Technical Reports Server (NTRS)
Towne, Charles E.; Schwab, John R.; Bui, Trong T.
1993-01-01
A computer code called Proteus 3D has been developed to solve the three dimensional, Reynolds averaged, unsteady compressible Navier-Stokes equations in strong conservation law form. The objective in this effort has been to develop a code for aerospace propulsion applications that is easy to use and easy to modify. Code readability, modularity, and documentation have been emphasized. The governing equations are solved in generalized non-orthogonal body-fitted coordinates by marching in time using a fully-coupled ADI solution procedure. The boundary conditions are treated implicitly. All terms, including the diffusion terms, are linearized using second-order Taylor series expansions. Turbulence is modeled using either an algebraic or two-equation eddy viscosity model. The thin-layer or Euler equations may also be solved. The energy equation may be eliminated by the assumption of constant total enthalpy. Explicit and implicit artificial viscosity may be used. Several time step options are available for convergence acceleration. The documentation is divided into three volumes. This is the Analysis Description, and presents the equations and solution procedure. It describes in detail the governing equations, the turbulence model, the linearization of the equations and boundary conditions, the time and space differencing formulas, the ADI solution procedure, and the artificial viscosity models.
NASA Astrophysics Data System (ADS)
Osman, Ahmad; Kaftandjian, Valérie; Hassler, Ulf
2012-04-01
The three dimensional (3D) X-ray computed tomography (3D-CT) has proven its successful application as an inspection method in nondestructive testing. The generated 3D volume uses high efficiency reconstruction algorithms containing all required information on the inner structures of the inspected part. Segmentation of this volume reveals suspicious regions that need to be classified as defective or false alarms. This paper deals with the classification step using data fusion theory, which was successfully applied on 2D X-ray data in previous work along with a support vector machine (SVM). For this study we chose a 3D-CT dataset of aluminium castings that needs to be fully inspected via X-ray CT to ensure their quality. We achieved a true classification rate of 97% on a validation dataset, which proves the effectiveness of the data fusion theory as a method to build a better classifier. Comparison with SVMs shows the importance of selecting the most pertinent features to improve the classifier performance and attaining 98% of true classification rate.
Proteus three-dimensional Navier-Stokes computer code, version 1.0. Volume 3: Programmer's reference
NASA Technical Reports Server (NTRS)
Towne, Charles E.; Schwab, John R.; Bui, Trong T.
1993-01-01
A computer code called Proteus 3D was developed to solve the three-dimensional, Reynolds-averaged, unsteady compressible Navier-Stokes equations in strong conservation law form. The objective in this effort was to develop a code for aerospace propulsion applications that is easy to use and easy to modify. Code readability, modularity, and documentation were emphasized. The governing equations are solved in generalized nonorthogonal body fitted coordinates, by marching in time using a fully-coupled ADI solution procedure. The boundary conditions are treated implicitly. All terms, including the diffusion terms, are linearized using second-order Taylor series expansions. Turbulence is modeled using either an algebraic or two-equation eddy viscosity model. The thin-layer or Euler equations may also be solved. The energy equation may be eliminated by the assumption of constant total enthalpy. Explicit and implicit artificial viscosity may be used. Several time step options are available for convergence acceleration. The documentation is divided into three volumes. The Programmer's Reference contains detailed information useful when modifying the program. The program structure, the Fortran variables stored in common blocks, and the details of each subprogram are described.
Shirai, Shintaro; Sato, Morio Suwa, Kazuhiro; Kishi, Kazushi; Shimono, Chigusa; Kawai, Nobuyuki; Tanihata, Hirohiko; Minamiguchi, Hiroki; Nakai, Motoki
2009-03-01
Purpose: To evaluate the safety and efficacy of three-dimensional conformal radiotherapy (3D-CRT) using single photon emission computed tomography (SPECT) in unresectable hepatocellular carcinoma (HCC) with portal vein tumor thrombus (PVTT). Methods and Materials: Patients with HCC with PVTT in the first branch and/or main trunk were selected for this study. The optimal beam directions for 3D-CRT were explored using a Tc-99m-galactosyl human serum albumin SPECT image for guidance. The SPECT image was classified as either wedge type or localized type. The clinical target volume to a total dose of 45 or 50 Gy per 18-20 fractions included the main tumor and PVTT in the wedge type and PVTT alone in the localized type. Results: Twenty-six patients were enrolled: 18 with wedge type and 8 with localized type. Mean tumor size was 7.1 cm (range, 4.4-12.3 cm). Clinical target volumes of wedge type vs. localized type were 111.2 cm{sup 3} vs. 48.4 cm{sup 3} (p = 0.010), respectively. Mean dose to normal liver and mean dose to functional liver were 1185 cGy and 988 cGy (p = 0.001) in wedge type and 1046 cGy and 1043 cGy (p = 0.658) in localized type, respectively. Despite an incidence of Child-Pugh B and C of 57.7%, no patients experienced radiation-induced liver disease. The progression of PVTT was inhibited, with an incidence of 92.2%; survival rates at 1 and 2 years were 44% and 30%, respectively. Conclusion: Single photon emission computed tomography-based 3D-CRT enables irradiation of both the main tumor and PVTT with low toxicity and promising survival.
NASA Astrophysics Data System (ADS)
Fan, Shuai; Li, Mo
2015-01-01
Concrete cracking and deterioration can potentially be addressed by innovative self-healing cementitious materials, which can autogenously regain transport properties and mechanical characteristics after the damage self-healing process. For the development of such materials, it is crucial, but challenging, to precisely characterize the extent and quality of self-healing due to a variety of factors. This study adopted x-ray computed microtomography (μCT) to derive three-dimensional morphological data on microcracks before and after healing in engineered cementitious composite (ECC). Scanning electron microscope and energy dispersive x-ray spectroscopy were also used to morphologically and chemically analyze the healing products. This work showed that the evolution of the microcrack 3D structure due to self-healing in cementitious materials can be directly and quantitatively characterized by μCT. A detailed description of the μCT image analysis method applied to ECC self-healing was presented. The results revealed that the self-healing extent and rate strongly depended on initial surface crack width, with smaller crack width favoring fast and robust self-healing. We also found that the self-healing mechanism in cementitious materials is dependent on crack depth. The region of a crack close to the surface (from 0 to around 50-150 μm below the surface) can be sealed quickly with crystalline precipitates. However, at greater depths the healing process inside the crack takes a significantly longer time to occur, with healing products more likely resulting from continued hydration and pozzolanic reactions. Finally, the μCT method was compared with other self-healing characterization methods, with discussions on its importance in generating new scientific knowledge for the development of robust self-healing cementitious materials.
Knackstedt, Christian; Muehlenbruch, Georg; Mischke, Karl; Bruners, Philipp; Schimpf, Thomas; Frechen, Dirk; Schummers, Georg; Mahnken, Andreas H.; Guenther, Rolf W.; Kelm, Malte; Schauerte, Patrick
2008-11-15
Information on the anatomy of the cardiac venous system (CVS) is increasingly important for cardiac resynchronization therapy or percutaneous transvenous mitral valve annuloplasty. Three-dimensional (3D) imaging can further improve the understanding of the relationship of cardiac structures. This study was performed to validate the accuracy of rotational coronary sinus angiography (CSA) displaying the 3D anatomy of the CVS compared to ECG-gated, contrast-enhanced, cardiac dual-source computed tomography (DSCT). Five domestic pigs (60 kg) underwent DSCT using a standardized examination protocol. Using a standard C-arm for fluoroscopy, a rotational CSA was obtained and 3D-image reconstructions performed. Side branches were identified using both methods and enumerated. Vessel visibility was estimated for each side branch and great cardiac vein/anterior interventricular vein. Also, vessel diameters were measured at distinct landmarks, i.e., side branching. The amount of contrast medium was determined and the effective radiation exposure of both methods was calculated. There was no significant difference regarding the vessel diameter of the great cardiac vein/anterior interventricular vein or its side branches. Also, estimation of vessel visibility was not different between the two imaging modalities. Estimated radiation exposure and amount of contrast medium were lower for rotational CSA. In conclusion, a 3D reconstruction of rotational CSA images is possible. All parts of the CVS are well depicted, allowing a 3D overview of the CVS anatomy. On-site 3D visualization might improve decision making during cardiac interventions. In contrast to DSCT, rotational CSA does not demonstrate the anatomy of the mitral annulus or the course of the left circumflex artery.
Parks, Connie L; Richard, Adam H; Monson, Keith L
2014-04-01
Facial approximation is the technique of developing a representation of the face from the skull of an unknown individual. Facial approximation relies heavily on average craniofacial soft tissue depths. For more than a century, researchers have employed a broad array of tissue depth collection methodologies, a practice which has resulted in a lack of standardization in craniofacial soft tissue depth research. To combat such methodological inconsistencies, Stephan and Simpson 2008 [15] examined and synthesized a large number of previously published soft tissue depth studies. Their comprehensive meta-analysis produced a pooled dataset of averaged tissue depths and a simplified methodology, which the researchers suggest be utilized as a minimum standard protocol for future craniofacial soft tissue depth research. The authors of the present paper collected craniofacial soft tissue depths using three-dimensional models generated from computed tomography scans of living males and females of four self-identified ancestry groups from the United States ranging in age from 18 to 62 years. This paper assesses the differences between: (i) the pooled mean tissue depth values from the sample utilized in this paper and those published by Stephan 2012 [21] and (ii) the mean tissue depth values of two demographically similar subsets of the sample utilized in this paper and those published by Rhine and Moore 1984 [16]. Statistical test results indicate that the tissue depths collected from the sample evaluated in this paper are significantly and consistently larger than those published by Stephan 2012 [21]. Although a lack of published variance data by Rhine and Moore 1984 [16] precluded a direct statistical assessment, a substantive difference was also concluded. Further, the dataset presented in this study is representative of modern American adults and is, therefore, appropriate for use in constructing contemporary facial approximations. PMID:24529417
Li, Jue; Inada, Shin; Schneider, Jurgen E.; Zhang, Henggui; Dobrzynski, Halina; Boyett, Mark R.
2014-01-01
The aim of the study was to develop a three-dimensional (3D) anatomically-detailed model of the rabbit right atrium containing the sinoatrial and atrioventricular nodes to study the electrophysiology of the nodes. A model was generated based on 3D images of a rabbit heart (atria and part of ventricles), obtained using high-resolution magnetic resonance imaging. Segmentation was carried out semi-manually. A 3D right atrium array model (∼3.16 million elements), including eighteen objects, was constructed. For description of cellular electrophysiology, the Rogers-modified FitzHugh-Nagumo model was further modified to allow control of the major characteristics of the action potential with relatively low computational resource requirements. Model parameters were chosen to simulate the action potentials in the sinoatrial node, atrial muscle, inferior nodal extension and penetrating bundle. The block zone was simulated as passive tissue. The sinoatrial node, crista terminalis, main branch and roof bundle were considered as anisotropic. We have simulated normal and abnormal electrophysiology of the two nodes. In accordance with experimental findings: (i) during sinus rhythm, conduction occurs down the interatrial septum and into the atrioventricular node via the fast pathway (conduction down the crista terminalis and into the atrioventricular node via the slow pathway is slower); (ii) during atrial fibrillation, the sinoatrial node is protected from overdrive by its long refractory period; and (iii) during atrial fibrillation, the atrioventricular node reduces the frequency of action potentials reaching the ventricles. The model is able to simulate ventricular echo beats. In summary, a 3D anatomical model of the right atrium containing the cardiac conduction system is able to simulate a wide range of classical nodal behaviours. PMID:25380074
WEN, ZHAOXIA; YAO, FENGQING; WANG, YUXING
2016-01-01
The present study aimed to describe the characteristics of cystic pancreatic tumors using computed tomography (CT) and to evaluate the diagnostic accuracy (DA) of post-imaging three-dimensional (3D) reconstruction. Clinical and imaging data, including multi-slice spiral CT scans, enhanced scans and multi-faceted reconstruction, from 30 patients with pathologically confirmed cystic pancreatic tumors diagnosed at the Linyi People's Hospital between August 2008 and June 2014 were retrospectively analyzed. Following the injection of Ultravist® 300 contrast agent, arterial, portal venous and parenchymal phase scans were obtained at 28, 60 and 150 sec, respectively, and 3D reconstructions of the CT images were generated. The average age of the patients was 38.4 years (range, 16–77 years), and the cohort included 5 males and 25 females (ratio, 1:5). The patients included 8 cases of mucinous cystadenoma (DA), 80%]; 9 cases of cystadenocarcinoma (DA, 84%); 6 cases of serous cystadenoma (DA, 100%); 3 cases of solid pseudopapillary tumor (DA, 100%); and 4 cases of intraductal papillary mucinous neoplasm (DA, 100%). 3D reconstructions of CT images were generated and, in the 4 cases of intraductal papillary mucinous neoplasm, the tumor was connected to the main pancreatic duct and multiple mural nodules were detected in one of these cases. The DA of the 3D-reconstructed images of cystic pancreatic tumors was 89.3%. The 64-slice spiral CT and 3D-reconstructed CT images facilitated the visualization of cystic pancreatic tumor characteristics, in particular the connections between the tumor and the main pancreatic duct. In conclusion, the 3D reconstruction of multi-slice CT data may provide an important source of information for the surgical team, in combination with the available clinical data. PMID:27073473
Lee, Hee Jin; Lee, Sungeun; Lee, Eun Joo; Song, In Ja; Kang, Byung-Cheol; Lee, Jae-Seo; Lim, Hoi-Jeong
2016-01-01
Purpose Facial asymmetry has been measured by the severity of deviation of the menton (Me) on posteroanterior (PA) cephalograms and three-dimensional (3D) computed tomography (CT). This study aimed to compare PA cephalograms and 3D CT regarding the severity of Me deviation and the direction of the Me. Materials and Methods PA cephalograms and 3D CT images of 35 patients who underwent orthognathic surgery (19 males and 16 females, with an average age of 22.1±3.3 years) were retrospectively reviewed in this study. By measuring the distance and direction of the Me from the midfacial reference line and the midsagittal plane in the cephalograms and 3D CT, respectively, the x-coordinates (x1 and x2) of the Me were obtained in each image. The difference between the x-coordinates was calculated and statistical analysis was performed to compare the severity of Me deviation and the direction of the Me in the two imaging modalities. Results A statistically significant difference in the severity of Me deviation was found between the two imaging modalities (Δx=2.45±2.03 mm, p<0.05) using the one-sample t-test. Statistically significant agreement was observed in the presence of deviation (k=0.64, p<0.05) and in the severity of Me deviation (k=0.27, p<0.05). A difference in the direction of the Me was detected in three patients (8.6%). The severity of the Me deviation was found to vary according to the imaging modality in 16 patients (45.7%). Conclusion The measurement of Me deviation may be different between PA cephalograms and 3D CT in some patients. PMID:27051637
Henak, C.R.; Abraham, C.L.; Peters, C.L.; Sanders, R.K.; Weiss, J.A.; Anderson, A.E.
2014-01-01
AIM To develop and demonstrate the efficacy of a computed tomography arthrography (CTA) protocol for the hip that enables accurate three-dimensional reconstructions of cartilage and excellent visualization of the acetabular labrum. MATERIALS AND METHODS Ninety-three subjects were imaged (104 scans); 68 subjects with abnormal anatomy, 11 patients after periacetabular osteotomy surgery, and 25 subjects with normal anatomy. Fifteen to 25 ml of contrast agent diluted with lidocaine was injected using a lateral oblique approach. A Hare traction splint applied traction during CT. The association between traction force and intra-articular joint space was assessed qualitatively under fluoroscopy. Cartilage geometry was reconstructed from the CTA images for 30 subjects; the maximum joint space under traction was measured. RESULTS Using the Hare traction splint, the intra-articular space and boundaries of cartilage could be clearly delineated throughout the joint; the acetabular labrum was also visible. Dysplastic hips required less traction (~5 kg) than normal and retroverted hips required (>10 kg) to separate the cartilage. An increase in traction force produced a corresponding widening of the intra-articular joint space. Under traction, the maximum width of the intra-articular joint space during CT ranged from 0.98–6.7 mm (2.46 ± 1.16 mm). CONCLUSIONS When applied to subjects with normal and abnormal hip anatomy, the CTA protocol presented yields clear delineation of the cartilage and the acetabular labrum. Use of a Hare traction splint provides a simple, cost-effective method to widen the intra-articular joint space during CT, and provides flexibility to vary the traction as required. PMID:25070373
Barra, Daniela A; Lima, Jailson C; Mauad Filho, Francisco; Araujo Júnior, Edward; Martins, Wellington P
2013-09-01
Our aim was to determine whether rotating the fetus over its largest axis and reducing the rotational step angle can improve reliability/agreement of fetal volume measurements obtained with three-dimensional ultrasonography (3-DUS). Two observers acquired three 3-DUS data sets for a fetus with a crown-rump length between 45 and 84 mm. These observers determined the fetal volume using virtual organ computer-aided analysis (VOCAL), by three different methods, with a rotational step angle of 30°: (1) minimal manipulation of the 3-DUS data set, fetus rotated over any axis; (2) manipulation of the 3-DUS data set until the fetus could be seen in a standardized manner, fetus rotated over its anteroposterior axis; (3) same 3-DUS data set manipulation, fetus rotated over its longitudinal axis. Intra- and inter-observer reliability/agreement was determined with intra-class correlation coefficients and limits of agreement. In addition, we tested the method that provided the best reliability/agreement results using 15° and 9° of rotational step angles. The time taken to manipulate 3-DUS and determine fetal volume was recorded. The best intra- and inter-observer reliability/agreement results were observed when the fetus was rotated over its longitudinal axis. Reducing rotational step angle to 15° or 9° did not further improve reliability/agreement. The observer took approximately 1 min to determine fetal volume using this method. Our findings indicate that fetal volume should be determined by rotating the fetus over its longitudinal axis, at a rotational step angle of 30°, which is relatively fast and allows analysis of fetal volume with good reliability and agreement. PMID:23791355
NASA Astrophysics Data System (ADS)
Torkaman, Saeed
2011-12-01
The focus of this research was to experimentally and computationally study air pressures and air flows through a model of the human larynx. The model, M6, was a symmetric, three-dimensional physical model. In this model, the transverse plane of the glottis was formed by half-sinusoidal arcs for each medial vocal fold surface, creating a maximum glottal width at the midcoronal section. To study the effects of different glottal shapes, three glottal angles were used, namely, 10° convergent, 0° uniform, and 10° divergent, with the single diameter of 0.16 cm. In addition, to capture the effects of changing glottal diameters, three diameters of 0.16, 0.04, and 0.01 cm in the midcoronal plane were used, all with the single angle of 0°, (i.e., the uniform glottis). Inasmuch as the uniform case with maximum diameter (0.16 cm) was the common case in both groups, a total of five distinct pairs of modeled vocal folds were used. Each case incorporated three rows of 14 pressure taps, located in the inferior-superior direction on the vocal fold surface at locations of the anterior (1/4), middle (1/2), and posterior (3/4) of the anterior-posterior span. This approach (i.e., empirically acquiring air pressure distributions at the three locations) has not been applied in prior studies. For each configuration, transglottal pressures of 0.294, 0.491, 0.981, 1.472, 1.962, and 2.453 kPa (i.e., 3, 5, 10, 15, 20, and 25 cm H2O) were used. To consider the effects of the presence of the arytenoid cartilages on the intraglottal pressures, a simplified model of the cartilages was fabricated as a single structure based on available physiological data, and the intraglottal pressures were measured with and without its presence. With the arytenoid cartilages structure in place, the glottis is an eccentric orifice. The empirical pressures were compared to computational results obtained with the CFD software package FLUENT. Also, flow visualization using a laser sheet and seeded airflow was
Kuboi, Nobuyuki Tatsumi, Tetsuya; Kinoshita, Takashi; Shigetoshi, Takushi; Fukasawa, Masanaga; Komachi, Jun; Ansai, Hisahiro
2015-11-15
The authors modeled SiN film etching with hydrofluorocarbon (CH{sub x}F{sub y}/Ar/O{sub 2}) plasma considering physical (ion bombardment) and chemical reactions in detail, including the reactivity of radicals (C, F, O, N, and H), the area ratio of Si dangling bonds, the outflux of N and H, the dependence of the H/N ratio on the polymer layer, and generation of by-products (HCN, C{sub 2}N{sub 2}, NH, HF, OH, and CH, in addition to CO, CF{sub 2}, SiF{sub 2}, and SiF{sub 4}) as ion assistance process parameters for the first time. The model was consistent with the measured C-F polymer layer thickness, etch rate, and selectivity dependence on process variation for SiN, SiO{sub 2}, and Si film etching. To analyze the three-dimensional (3D) damage distribution affected by the etched profile, the authors developed an advanced 3D voxel model that can predict the time-evolution of the etched profile and damage distribution. The model includes some new concepts for gas transportation in the pattern using a fluid model and the property of voxels called “smart voxels,” which contain details of the history of the etching situation. Using this 3D model, the authors demonstrated metal–oxide–semiconductor field-effect transistor SiN side-wall etching that consisted of the main-etch step with CF{sub 4}/Ar/O{sub 2} plasma and an over-etch step with CH{sub 3}F/Ar/O{sub 2} plasma under the assumption of a realistic process and pattern size. A large amount of Si damage induced by irradiated hydrogen occurred in the source/drain region, a Si recess depth of 5 nm was generated, and the dislocated Si was distributed in a 10 nm deeper region than the Si recess, which was consistent with experimental data for a capacitively coupled plasma. An especially large amount of Si damage was also found at the bottom edge region of the metal–oxide–semiconductor field-effect transistors. Furthermore, our simulation results for bulk fin-type field-effect transistor side-wall etching
Almukhtar, A; Ayoub, A; Khambay, B; McDonald, J; Ju, X
2016-09-01
We describe the comprehensive 3-dimensional analysis of facial changes after Le Fort I osteotomy and introduce a new tool for anthropometric analysis of the face. We studied the cone-beam computed tomograms of 33 patients taken one month before and 6-12 months after Le Fort I maxillary advancement with or without posterior vertical impaction. Use of a generic facial mesh for dense correspondence analysis of changes in the soft tissue showed a mean (SD) anteroposterior advancement of the maxilla of 5.9 (1.7) mm, and mean (SD) minimal anterior and posterior vertical maxillary impaction of 0.1 (1.7) mm and 0.6 (1.45) mm, respectively. It also showed distinctive forward and marked lateral expansion around the upper lip and nose, and pronounced upward movement of the alar curvature and columella. The nose was widened and the nostrils advanced. There was minimal forward change at the base of the nose (subnasale and alar base) but a noticeable upward movement at the nasal tip. Changes at the cheeks were minimal. Analysis showed widening of the midface and upper lip which, to our knowledge, has not been reported before. The nostrils were compressed and widened, and the lower lip shortened. Changes at the chin and lower lip were secondary to the limited maxillary impaction. PMID:27325452
Spezi, Emiliano; Downes, Patrick; Jarvis, Richard; Radu, Emil; Staffurth, John
2012-05-01
Purpose: The purpose of the present study was to quantify the concomitant dose received by patients undergoing cone beam computed tomography (CBCT) scanning in different clinical scenarios as a part of image-guided radiotherapy (IGRT) procedures. Methods and Materials: We calculated the three-dimensional concomitant dose received as a result of CBCT scans in 6 patients representing different clinical scenarios: two pelvis, two head and neck, and two chest. We assessed the effect that a daily on-line IGRT strategy would have on the patient dose distribution, assuming 40 CBCT scans throughout the treatment course. The additional dose to the planning target volume margin region was also estimated. Results: In the pelvis, a single CBCT scan delivered a mean dose to the femoral heads of 2-6 cGy and the rectum of 1-2 cGy. An additional dose to the planning target volume was within 1-3 cGy. In the chest, the mean dose to the planning target volume varied from 2.5 to 5 cGy. The lung and spinal cord planning organ at risk volume received {<=}4 cGy and {<=}5 cGy, respectively. In the head and neck, a single CBCT scan delivered a mean dose of 0.3 cGy, with bony structures receiving 0.5-0.8 cGy. The femoral heads received an additional dose of 1.5-2.5 Gy. A reduction of 20-30% in the mean dose to the organs at risk was achieved using bowtie filtration. In the head and neck, the dose to the eyes and brainstem was eliminated by decreasing the craniocaudal field size. Conclusions: The additional dose from on-line IGRT procedures can be clinically relevant. The organ dose can be significantly reduced with the use of appropriate patient-specific settings. The concomitant dose from CBCT should be accounted for and the acquisition settings optimized for optimal IGRT strategies on a patient basis.
Godlewski, G; Gaubert, J; Gaubert-Cristol, R; Dauzat, M; Aldréa, F; Prudhomme, M
2004-10-01
In bile duct morphogenesis it has been established that the extrahepatic bile ducts in human originate from hepatic diverticulum while intrahepatic bile ducts arise from the ductal plate (DP), a network of primitive biliary epithelium that develops in the periportal connective tissue. The aim of this work was to reconstruct in rat embryos, stages 19-23, the three-dimensional (3D) distribution of the DP by means of a computer-assisted method. Six specimens, stages 19-23, fixed, dehydrated and paraffin-embedded, were submitted to serial histological sections and stained by hematoxylin-eosin and Heidenhain techniques. The images were directly digitalized with a CCD camera. The serial views were aligned anatomically by software and the data were analyzed following segmentation and thresholding. At stage 19, the DP was not yet organized. The periportal mesoderm (M) was gaining ground with some cords of cubic cells evoking primitive ductal cells. At stage 20, a row of ductal cubic cells went around the transverse portal sinus at the junction between M and liver cells. At stage 21, the DP developed at the periphery of periportal connective tissue and appeared in direct continuity with the hepatic duct (HDu). Four evaginations emerged from the DP and were growing up in the hepatic parenchyma. At stage 23, the DP appeared as a large network in continuity with the HDu located at the periphery of periportal M and presenting several evaginations radiating in the liver parenchyma. This work in the rat embryo permits the clear visualization of the development of the junctional zone in the hepatic hilum. Three phenomena are observed: (1) proximal left and right hepatic ducts and their segmental branches are derived from DP and not from the HDu; (2) the extrahepatic biliary system is in contact with the developing hilar ducts; (3) ductal maturation begins at the hilum and proceeds centrifugally. These observations are of great relevance in explaining pathological changes appearing
Gantet, Pierre; Payoux, Pierre; Celler, Anna; Majorel, Cynthia; Gourion, Daniel; Noll, Dominikus; Esquerre, Jean-Paul
2006-01-15
Single photon emission computed tomography imaging suffers from poor spatial resolution and high statistical noise. Consequently, the contrast of small structures is reduced, the visual detection of defects is limited and precise quantification is difficult. To improve the contrast, it is possible to include the spatially variant point spread function of the detection system into the iterative reconstruction algorithm. This kind of method is well known to be effective, but time consuming. We have developed a faster method to account for the spatial resolution loss in three dimensions, based on a postreconstruction restoration method. The method uses two steps. First, a noncorrected iterative ordered subsets expectation maximization (OSEM) reconstruction is performed and, in the second step, a three-dimensional (3D) iterative maximum likelihood expectation maximization (ML-EM) a posteriori spatial restoration of the reconstructed volume is done. In this paper, we compare to the standard OSEM-3D method, in three studies (two in simulation and one from experimental data). In the two first studies, contrast, noise, and visual detection of defects are studied. In the third study, a quantitative analysis is performed from data obtained with an anthropomorphic striatal phantom filled with 123-I. From the simulations, we demonstrate that contrast as a function of noise and lesion detectability are very similar for both OSEM-3D and OSEM-R methods. In the experimental study, we obtained very similar values of activity-quantification ratios for different regions in the brain. The advantage of OSEM-R compared to OSEM-3D is a substantial gain of processing time. This gain depends on several factors. In a typical situation, for a 128x128 acquisition of 120 projections, OSEM-R is 13 or 25 times faster than OSEM-3D, depending on the calculation method used in the iterative restoration. In this paper, the OSEM-R method is tested with the approximation of depth independent
NASA Astrophysics Data System (ADS)
Malek, Gary A.
Due to the prodigious amount of electrical energy consumed throughout the world, there exists a great demand for new and improved methods of generating electrical energy in a clean and renewable manner as well as finding more effective ways to store it. This enormous task is of great interest to scientists and engineers, and much headway is being made by utilizing three-dimensional (3D) nanostructured materials. This work explores the application of two types of 3D nanostructured materials toward fabrication of advanced electrical energy storage and conversion devices. The first nanostructured material consists of vertically aligned carbon nanofibers. This three-dimensional structure is opaque, electrically conducting, and contains active sites along the outside of each fiber that are conducive to chemical reactions. Therefore, they make the perfect 3D conducting nanostructured substrate for advanced energy storage devices. In this work, the details for transforming vertically aligned carbon nanofiber arrays into core-shell structures via atomic layer deposition as well as into a mesoporous manganese oxide coated supercapacitor electrode are given. Another unique type of three-dimensional nanostructured substrate is nanotextured glass, which is transparent but non-conducting. Therefore, it can be converted to a 3D transparent conductor for possible application in photovoltaics if it can be conformally coated with a conducting material. This work details that transformation as well as the addition of plasmonic gold nanoparticles to complete the transition to a 3D plasmonic transparent conductor.
Morgan, D.O.; Robinson, A.T.; Allen, D.A.; Picton, D.J.; Thornton, D.A.; Shaw, S.E.
2011-07-01
This paper describes the development of a three-dimensional methodology for the assessment of neutron damage and nuclear energy deposition (or nuclear heating) throughout the graphite cores of the UK's Advanced Gas-cooled Reactors. Advances in the development of the Monte Carlo radiation transport code MCBEND have enabled the efficient production of detailed fully three-dimensional models that utilise three-dimensional source distributions obtained from Core Follow data supplied by the reactor physics code PANTHER. The calculational approach can be simplified to reduce both the requisite number of intensive radiation transport calculations, as well as the quantity of data output. These simplifications have been qualified by comparison with explicit calculations and they have been shown not to introduce significant systematic uncertainties. Simple calculational approaches are described that allow users of the data to address the effects on neutron damage and nuclear energy deposition predictions of the feedback resulting from the mutual dependencies of graphite weight loss and nuclear energy deposition. (authors)
NASA Astrophysics Data System (ADS)
Zhang, M.; Zhang, Y.; Lichtner, P. C.
2013-12-01
/tailing behavior of the FHM can generally be captured by the HSMs. At all the variances tested, the 8-unit upscaled model is always the most accurate. When the variance is low to moderate, this model can provide accurate to adequate predictions of all the FHM plume moments. In addition, upscaled dispersivities computed with the stochastic versus deterministic techniques yield similar solute predictions, which suggest that in this analysis, an ergodic transport regime has emerged. However, when the variance of ln(k) increases to 4.5, the upscaled dispersivities predicted by the stochastic methods result in significant upstream dispersion that is nonphysical. In this case, the HSMs cannot capture the FHM plume moments for the given ln(K) variance. In summary, simulation results suggest that the upscaling dispersivity can be used to accurately capture solute transport in low ln(K) variance systems but fails to describe the solute motion if system variance is high. Reference: Mingkan Zhang, and Ye Zhang, Multiscale, Multi-variance Dispersivity Upscaling for A Three-Dimensional Hierarchical Aquifer: Developing and Testing a Parallel Random Walk Method with a Drift Term in the Dispersion Tensor, Water Resources Research, in preparation.
NASA Astrophysics Data System (ADS)
Fanelli, Fiorenza; Bosso, Piera; Mastrangelo, Anna Maria; Fracassi, Francesco
2016-07-01
Surface processing of materials by atmospheric pressure dielectric barrier discharges (DBDs) has experienced significant growth in recent years. Considerable research efforts have been directed for instance to develop a large variety of processes which exploit different DBD electrode geometries for the direct and remote deposition of thin films from precursors in gas, vapor and aerosol form. This article briefly reviews our recent progress in thin film deposition by DBDs with particular focus on process optimization. The following examples are provided: (i) the plasma-enhanced chemical vapor deposition of thin films on an open-cell foam accomplished by igniting the DBD throughout the entire three-dimensional (3D) porous structure of the substrate, (ii) the preparation of hybrid organic/inorganic nanocomposite coatings using an aerosol-assisted process, (iii) the DBD jet deposition of coatings containing carboxylic acid groups and the improvement of their chemical and morphological stability upon immersion in water.
Wang, Shaofu; Qu, Dandan; Jiang, Yun; Xiong, Wan-Sheng; Sang, Hong-Qian; He, Rong-Xiang; Tai, Qidong; Chen, Bolei; Liu, Yumin; Zhao, Xing-Zhong
2016-08-10
Three-dimensional branched TiO2 architectures (3D BTA) with controllable morphologies were synthesized via a facile template-free one-pot solvothermal route. The volume ratio of deionized water (DI water) and diethylene glycol in solvothermal process is key to the formation of 3D BTA assembled by nanowire-coated TiO2 dendrites, which combines the advantages of 3D hierarchical structure and 1D nanoscale building blocks. Benefiting from such unique structural features, the BTA in full bloom achieved significantly increased specific surface areas and shortened Li(+) ion/electrons diffusion pathway. The lithium-ion batteries based on BTA in full bloom exhibited remarkably enhanced reversible specific capacity and rate performance, attributing to the high contact area with the electrolyte and the short solid state diffusion pathway for Li(+) ion/electrons promoting lithium insertion and extraction. PMID:27420343
Sang, Yan-Hui; Hu, Hong-Cheng; Lu, Song-He; Wu, Yu-Wei; Li, Wei-Ran; Tang, Zhi-Hui
2016-01-01
Background: The accuracy of three-dimensional (3D) reconstructions from cone-beam computed tomography (CBCT) has been particularly important in dentistry, which will affect the effectiveness of diagnosis, treatment plan, and outcome in clinical practice. The aims of this study were to assess the linear, volumetric, and geometric accuracy of 3D reconstructions from CBCT and to investigate the influence of voxel size and CBCT system on the reconstructions results. Methods: Fifty teeth from 18 orthodontic patients were assigned to three groups as NewTom VG 0.15 mm group (NewTom VG; voxel size: 0.15 mm; n = 17), NewTom VG 0.30 mm group (NewTom VG; voxel size: 0.30 mm; n = 16), and VATECH DCTPRO 0.30 mm group (VATECH DCTPRO; voxel size: 0.30 mm; n = 17). The 3D reconstruction models of the teeth were segmented from CBCT data manually using Mimics 18.0 (Materialise Dental, Leuven, Belgium), and the extracted teeth were scanned by 3Shape optical scanner (3Shape A/S, Denmark). Linear and volumetric deviations were separately assessed by comparing the length and volume of the 3D reconstruction model with physical measurement by paired t-test. Geometric deviations were assessed by the root mean square value of the imposed 3D reconstruction and optical models by one-sample t-test. To assess the influence of voxel size and CBCT system on 3D reconstruction, analysis of variance (ANOVA) was used (α = 0.05). Results: The linear, volumetric, and geometric deviations were −0.03 ± 0.48 mm, −5.4 ± 2.8%, and 0.117 ± 0.018 mm for NewTom VG 0.15 mm group; −0.45 ± 0.42 mm, −4.5 ± 3.4%, and 0.116 ± 0.014 mm for NewTom VG 0.30 mm group; and −0.93 ± 0.40 mm, −4.8 ± 5.1%, and 0.194 ± 0.117 mm for VATECH DCTPRO 0.30 mm group, respectively. There were statistically significant differences between groups in terms of linear measurement (P < 0.001), but no significant difference in terms of volumetric measurement (P = 0.774). No statistically significant difference were
NASA Technical Reports Server (NTRS)
Louis, P.; Gokhale, A. M.
1996-01-01
Computer simulation is a powerful tool for analyzing the geometry of three-dimensional microstructure. A computer simulation model is developed to represent the three-dimensional microstructure of a two-phase particulate composite where particles may be in contact with one another but do not overlap significantly. The model is used to quantify the "connectedness" of the particulate phase of a polymer matrix composite containing hollow carbon particles in a dielectric polymer resin matrix. The simulations are utilized to estimate the morphological percolation volume fraction for electrical conduction, and the effective volume fraction of the particles that actually take part in the electrical conduction. The calculated values of the effective volume fraction are used as an input for a self-consistent physical model for electrical conductivity. The predicted values of electrical conductivity are in very good agreement with the corresponding experimental data on a series of specimens having different particulate volume fraction.
Creating Three-Dimensional Scenes
ERIC Educational Resources Information Center
Krumpe, Norm
2005-01-01
Persistence of Vision Raytracer (POV-Ray), a free computer program for creating photo-realistic, three-dimensional scenes and a link for Mathematica users interested in generating POV-Ray files from within Mathematica, is discussed. POV-Ray has great potential in secondary mathematics classrooms and helps in strengthening students' visualization…
Three-dimensional stellarator codes
Garabedian, P. R.
2002-01-01
Three-dimensional computer codes have been used to develop quasisymmetric stellarators with modular coils that are promising candidates for a magnetic fusion reactor. The mathematics of plasma confinement raises serious questions about the numerical calculations. Convergence studies have been performed to assess the best configurations. Comparisons with recent data from large stellarator experiments serve to validate the theory. PMID:12140367
Three-dimensional marginal separation
NASA Technical Reports Server (NTRS)
Duck, Peter W.
1988-01-01
The three dimensional marginal separation of a boundary layer along a line of symmetry is considered. The key equation governing the displacement function is derived, and found to be a nonlinear integral equation in two space variables. This is solved iteratively using a pseudo-spectral approach, based partly in double Fourier space, and partly in physical space. Qualitatively, the results are similar to previously reported two dimensional results (which are also computed to test the accuracy of the numerical scheme); however quantitatively the three dimensional results are much different.
NASA Astrophysics Data System (ADS)
Tippayakul, Chanatip
upgraded to be able to model various temperatures across different materials of the fuel element in the reactor core. The analysis of the temperature modeling capability demonstrated expected reactivity loss as a function of temperature. Secondly, the depletion capability of TRIGSIM was tremendously improved. The upgrade of the depletion capability involved the replacement of the simple predictor depletion algorithm used in the original TRIGSIM with the more advanced predictor-corrector depletion algorithm. Moreover, the methodology of combining the online burnup cross section generation from the Monte Carlo for "important" isotopes and the use of pre-generated TRIGA burnup cross section library for "non-important" isotopes was implemented in the new TRIGSIM as well. For the last part of the improvements of depletion capability, TRIGSIM was modified to be able to perform depletion calculations in several axial nodes which reflects better burnup gradient along the axial direction. Thirdly, the possibility to speed up the Monte Carlo calculation was studied and implemented. In this research, the speedup of the Monte Carlo calculation was performed by utilizing the fast nodal diffusion calculation to provide initial source distribution for the Monte Carlo method. The results showed that the some computational time was saved by eliminating the typical guess of large number of inactive cycles. Along with this speedup methodology, the algorithm to generate the consistent diffusion cross section from the Monte Carlo was also developed. In addition, the speed of the new fuel management system was also possible by the utilization of parallel computing as it was illustrated that parallel computing had a great potential for reducing clock time. Finally, the upgraded TRIGSIM was renamed as TRIGSIMS to reflect these major improvements. Subsequently, the new TRIGSIMS was validated by performing several core loading configurations starting from the first operating core loading (core
Dong, Haifeng; Liu, Conghui; Ye, Haitao; Hu, Linping; Fugetsu, Bunshi; Dai, Wenhao; Cao, Yu; Qi, Xueqiang; Lu, Huiting; Zhang, Xueji
2015-01-01
An efficient three-dimensional (3D) hybrid material of nitrogen-doped graphene sheets (N-RGO) supporting molybdenum disulfide (MoS2) nanoparticles with high-performance electrocatalytic activity for hydrogen evolution reaction (HER) is fabricated by using a facile hydrothermal route. Comprehensive microscopic and spectroscopic characterizations confirm the resulting hybrid material possesses a 3D crumpled few-layered graphene network structure decorated with MoS2 nanoparticles. Electrochemical characterization analysis reveals that the resulting hybrid material exhibits efficient electrocatalytic activity toward HER under acidic conditions with a low onset potential of 112 mV and a small Tafel slope of 44 mV per decade. The enhanced mechanism of electrocatalytic activity has been investigated in detail by controlling the elemental composition, electrical conductance and surface morphology of the 3D hybrid as well as Density Functional Theory (DFT) calculations. This demonstrates that the abundance of exposed active sulfur edge sites in the MoS2 and nitrogen active functional moieties in N-RGO are synergistically responsible for the catalytic activity, whilst the distinguished and coherent interface in MoS2/N-RGO facilitates the electron transfer during electrocatalysis. Our study gives insights into the physical/chemical mechanism of enhanced HER performance in MoS2/N-RGO hybrids and illustrates how to design and construct a 3D hybrid to maximize the catalytic efficiency. PMID:26639026
NASA Astrophysics Data System (ADS)
Dong, Haifeng; Liu, Conghui; Ye, Haitao; Hu, Linping; Fugetsu, Bunshi; Dai, Wenhao; Cao, Yu; Qi, Xueqiang; Lu, Huiting; Zhang, Xueji
2015-12-01
An efficient three-dimensional (3D) hybrid material of nitrogen-doped graphene sheets (N-RGO) supporting molybdenum disulfide (MoS2) nanoparticles with high-performance electrocatalytic activity for hydrogen evolution reaction (HER) is fabricated by using a facile hydrothermal route. Comprehensive microscopic and spectroscopic characterizations confirm the resulting hybrid material possesses a 3D crumpled few-layered graphene network structure decorated with MoS2 nanoparticles. Electrochemical characterization analysis reveals that the resulting hybrid material exhibits efficient electrocatalytic activity toward HER under acidic conditions with a low onset potential of 112 mV and a small Tafel slope of 44 mV per decade. The enhanced mechanism of electrocatalytic activity has been investigated in detail by controlling the elemental composition, electrical conductance and surface morphology of the 3D hybrid as well as Density Functional Theory (DFT) calculations. This demonstrates that the abundance of exposed active sulfur edge sites in the MoS2 and nitrogen active functional moieties in N-RGO are synergistically responsible for the catalytic activity, whilst the distinguished and coherent interface in MoS2/N-RGO facilitates the electron transfer during electrocatalysis. Our study gives insights into the physical/chemical mechanism of enhanced HER performance in MoS2/N-RGO hybrids and illustrates how to design and construct a 3D hybrid to maximize the catalytic efficiency.
NASA Astrophysics Data System (ADS)
Martin, R.; Orgogozo, L.; Noiriel, C. N.; Guibert, R.; Golfier, F.; Debenest, G.; Quintard, M.
2013-05-01
In the context of biofilm growth in porous media, we developed high performance computing tools to study the impact of biofilms on the fluid transport through pores of a solid matrix. Indeed, biofilms are consortia of micro-organisms that are developing in polymeric extracellular substances that are generally located at a fluid-solid interfaces like pore interfaces in a water-saturated porous medium. Several applications of biofilms in porous media are encountered for instance in bio-remediation methods by allowing the dissolution of organic pollutants. Many theoretical studies have been done on the resulting effective properties of these modified media ([1],[2], [3]) but the bio-colonized porous media under consideration are mainly described following simplified theoretical media (stratified media, cubic networks of spheres ...). Therefore, recent experimental advances have provided tomography images of bio-colonized porous media which allow us to observe realistic biofilm micro-structures inside the porous media [4]. To solve closure system of equations related to upscaling procedures in realistic porous media, we solve the velocity field of fluids through pores on complex geometries that are described with a huge number of cells (up to billions). Calculations are made on a realistic 3D sample geometry obtained by X micro-tomography. Cell volumes are coming from a percolation experiment performed to estimate the impact of precipitation processes on the properties of a fluid transport phenomena in porous media [5]. Average permeabilities of the sample are obtained from velocities by using MPI-based high performance computing on up to 1000 processors. Steady state Stokes equations are solved using finite volume approach. Relaxation pre-conditioning is introduced to accelerate the code further. Good weak or strong scaling are reached with results obtained in hours instead of weeks. Factors of accelerations of 20 up to 40 can be reached. Tens of geometries can now be
Guo, Y; Tian, G L
2011-02-01
We established the maximum length and the position of the long axis of the scaphoid from three-dimensional reconstructions of spiral computed tomography in 30 pairs of wrists. The distance between two points on the three-dimensional scaphoid surface model were calculated using commercially available software and corresponding coordinates of the two points were documented. The mean length was 29.3 (SD 1.6) mm for men and 26.6 (SD 1.8) mm for women. The location of the distal point was at the centre of the scaphoid tuberosity, with the proximal point of the long axis located at the dorsal ridge of the scapholunate facet. PMID:20732928
2014-01-01
Background Sinusitis is a common disease in the horse. In human medicine it is described, that obstruction of the sinonasal communication plays a major role in the development of sinusitis. To get spatial sense of the equine specific communication ways between the nasal cavity and the paranasal sinuses, heads of 19 horses, aged 2 to 26 years, were analyzed using three-dimensional (3D) reformatted renderings of CT-datasets. Three-dimensional models were generated following manual and semi-automated segmentation. Before segmentation, the two-dimensional (2D) CT-images were verified against corresponding frozen sections of cadaveric heads. Results Three-dimensional analysis of the paranasal sinuses showed the bilateral existence of seven sinus compartments: rostral maxillary sinus, ventral conchal sinus, caudal maxillary sinus, dorsal conchal sinus, frontal sinus, sphenopalatine sinus and middle conchal sinus. The maxillary septum divides these seven compartments into two sinus systems: a rostral paranasal sinus system composed of the rostral maxillary sinus and the ventral conchal sinus and a caudal paranasal sinus system which comprises all other sinuses. The generated 3D models revealed a typically configuration of the sinonasal communication ways. The sinonasal communication started within the middle nasal meatus at the nasomaxillary aperture (Apertura nasomaxillaris), which opens in a common sinonasal channel (Canalis sinunasalis communis). This common sinonasal channel ramifies into a rostral sinonasal channel (Canalis sinunasalis rostralis) and a caudo-lateral sinonasal channel (Canalis sinunasalis caudalis). The rostral sinonasal channel ventilated the rostral paranasal sinus system, the caudo-lateral sinonasal channel opened into the caudal paranasal sinus system. The rostral sinonasal channel was connected to the rostral paranasal sinuses in various ways. Whereas, the caudal channel showed less anatomical variations and was in all cases connected to the
Battista, J J; Sharpe, M B
1992-12-01
The objective of radiation therapy is to concentrate a prescribed radiation dose accurately within a target volume in the patient. Major advances in imaging technology have greatly improved our ability to plan radiation treatments in three dimensions (3D) and to verify the treatment geometrically, but there is a concomitant need to improve dosimetric accuracy. It has been recommended that radiation doses should be computed with an accuracy of 3% within the target volume and in radiosensitive normal tissues. We review the rationale behind this recommendation, and describe a new generation of 3D dose algorithms which are capable of achieving this goal. A true 3D dose calculation tracks primary and scattered radiations in 3D space while accounting for tissue inhomogeneities. In the past, dose distributions have been computed in a 2D transverse slice with the assumption that the anatomy of the patient dose not change abruptly in nearby slices. We demonstrate the importance of computing 3D scatter contributions to dose from photons and electrons correctly, and show the magnitude of dose errors caused by using traditional 2D methods. The Monte Carlo technique is the most general and rigorous approach since individual primary and secondary particle tracks are simulated. However, this approach is too time-consuming for clinical treatment planning. We review an approach that is based on the superposition principle and achieves a reasonable compromise between the speed of computation and accuracy in dose. In this approach, dose deposition is separated into two steps. Firstly, the attenuation of incident photons interacting in the absorber is computed to determine the total energy released in the material (TERMA). This quantity is treated as an impulse at each irradiated point. Secondly, the transport of energy by scattered photons and electrons is described by a point dose spread kernel. The dose distribution is the superposition of the kernels, weighted by the magnitude of
NASA Astrophysics Data System (ADS)
Owkes, Mark; Desjardins, Olivier
2014-08-01
In this work, a novel computational framework for calculating convection fluxes is developed and employed in the context of the piecewise linear interface calculation (PLIC) volume-of-fluid (VOF) method. The scheme is three-dimensional, unsplit, discretely conservative, and bounded. The scheme leverages the idea of semi-Lagrangian transport to estimate the amount of liquid that is fluxed through each face during a time-step. The present work can be seen as an extension of the two-dimensional EMFPA method of López et al. (2004) [16] to three dimensions and an improvement of the three-dimensional FMFPA-3D method of Hernández et al. (2008) [17] with the addition of discrete conservation. In FMFPA-3D, fluxes of liquid volume fraction are calculated by transporting a cell face back in time with a semi-Lagrangian method that uses cell face edge velocities to produce a flux hexahedron with flat faces. The flux hexahedron may overlap with neighboring fluxes hindering the conservation properties of the method. The proposed method computes the fluxes by transporting the cell face back in time using a semi-Lagrangian step based on the cell face corner velocities, which results in a three-dimensional, generalized flux hexahedron that does not typically have flat faces. However, the flux volumes do not overlap and discrete conservation can be achieved. The complex flux volume is partitioned into a collection of simplices and a simple sign convention allows the calculation of the flux to be reduced to a straightforward and systematic algorithm. The proposed VOF scheme is tested on multiple benchmark cases including Zalesak's disk, two- and three-dimensional deformation tests, and the evolution of a droplet in homogeneous isotropic turbulence.
NASA Technical Reports Server (NTRS)
Sheng, Chunhua; Hyams, Daniel G.; Sreenivas, Kidambi; Gaither, J. Adam; Marcum, David L.; Whitfield, David L.
2000-01-01
A multiblock unstructured grid approach is presented for solving three-dimensional incompressible inviscid and viscous turbulent flows about complete configurations. The artificial compressibility form of the governing equations is solved by a node-based, finite volume implicit scheme which uses a backward Euler time discretization. Point Gauss-Seidel relaxations are used to solve the linear system of equations at each time step. This work employs a multiblock strategy to the solution procedure, which greatly improves the efficiency of the algorithm by significantly reducing the memory requirements by a factor of 5 over the single-grid algorithm while maintaining a similar convergence behavior. The numerical accuracy of solutions is assessed by comparing with the experimental data for a submarine with stem appendages and a high-lift configuration.
Oda, Akifumi; Kobayashi, Kana; Takahashi, Ohgi
2010-01-01
N-Acetyltransferase 2 (NAT2) is one of the most important polymorphic drug-metabolizing enzymes and plays a significant role in individual differences of drug efficacies and/or side effects. Coenzyme A (CoA) is a cofactor in the experimentally determined crystal structure of NAT2, although the acetyl source of acetylation reactions catalyzed by NAT is not CoA, but rather acetyl CoA. In this study, the three-dimensional structure of NAT2, including acetyl CoA, was calculated using molecular dynamics simulation. By substituting acetyl CoA for CoA the amino acid residue Gly286, which is known to transform into a glutamate residue by NAT2*7A and NAT2*7B, comes close to the cofactor binding site. In addition, the binding pocket around the sulfur atom of acetyl CoA expanded in the NAT2-acetyl CoA complex. PMID:20930369
Three Dimensional Illustrating--Three-Dimensional Vision and Deception of Sensibility
ERIC Educational Resources Information Center
Szállassy, Noémi; Gánóczy, Anita; Kriska, György
2009-01-01
The wide-spread digital photography and computer use gave the opportunity for everyone to make three-dimensional pictures and to make them public. The new opportunities with three-dimensional techniques give chance for the birth of new artistic photographs. We present in detail the biological roots of three-dimensional visualization, the phenomena…
Fulton, D R; Marx, G R; Pandian, N G; Romero, B A; Mumm, B; Krauss, M; Wollschläger, H; Ludomirsky, A; Cao, Q L
1994-03-01
Three-dimensional cardiac reconstruction generated from transesophageal interrogation can be performed using an integrated unit that captures, processes, and postprocesses tomographic parallel slices of the heart. This probe was used for infants and young children in the transthoracic position to evaluate the feasibility of producing three-dimensional cardiac images with capability for real-time dynamic display. Twenty-two infants and children (range 1 day-3.5 years) underwent image acquisition using a 16 mm 5 MHz 64 element probe placed over the precordium. Two infants were also imaged from the subcostal position. Data was obtained and stored over a single cardiac cycle after acceptable cardiac and respiratory gating intervals were met. The transducer was advanced in 0.5-1 mm increments over the cardiac structures using identical acquisition criteria. The images were reconstructed from the stored digital cubic format and could be oriented in any desired plane. In 9 of the 22 infants the images obtained were of optimal quality. The images obtained displayed normal cardiac structures emphasizing depth relationships as well as visualization of planes not generally demonstrated by two-dimensional imaging. Several lesions were also depicted in a unique fashion using this technique. Though the method employed was limited by movement artifact and reconstruction time, the quality of the three-dimensional display was excellent and enhanced by real-time demonstration. The transthoracic approach was successful in capturing sufficient data to create three-dimensional images, which may have further application in more accurate diagnosis of complex cardiac abnormalities and generation of planes of view which could duplicate surgical visualization of a lesion. Further assessment of the technique in infants with congenital heart disease is warranted. PMID:10146717
Shim, Youn-Soo; Kim, Ah-Hyeon; Choi, Ja-Eun; An, So-Youn
2014-01-01
Advances in computed tomography (CT) technology - from traditional CT to cone beam (CB) CT - have benefitted both the dentists and their young patients. We therefore wanted to determine the prevalence of CBCT use in pediatric dentistry in Korea. Our first approach was to conduct an institutional survey to evaluate the use of CBCT for diagnosing and evaluating dental problems in pediatric patients. Our second approach was to review any articles published during 2002-2011 in the Journal of the Korean Academy of Pediatric Dentistry that described clinical use of CBCT. The journal articles surveyed indicated that there were three areas in which CBCT was most useful. The most prevalent use was for diagnosis and monitoring of the growth of cystomas and other tumors in the mouth. The second most common use of CBCT was localization of impacted teeth and evaluation of their relations with adjacent teeth. The third use was to observe supernumerary teeth and evaluate their relations with the roots of adjacent teeth. Compared with traditional CT, CBCT has shorter acquisition times and causes less radiation exposure to the patient. There are fewer side effects with CBCT because its accuracy allows minimally invasive treatment for such problems as impacted and supernumerary teeth. PMID:24704642
Clausen, Philip; Wroe, Stephen; McHenry, Colin; Moreno, Karen; Bourke, Jason
2008-11-14
We present results from a detailed three-dimensional finite element analysis of the cranium and mandible of the Australian dingo (Canis lupus dingo) during a range of feeding activities and compare results with predictions based on two-dimensional methodology [Greaves, W.S., 2000. Location of the vector of jaw muscle force in mammals. Journal of Morphology 243, 293-299]. Greaves showed that the resultant muscle vector intersects the mandible line slightly posterior to the lower third molar (m3). Our work demonstrates that this is qualitatively correct, although the actual point is closer to the jaw joint. We show that it is theoretically possible for the biting side of the mandible to dislocate during unilateral biting; however, the bite point needs to be posterior to m3. Simulations show that reduced muscle activation on the non-biting side can considerably diminish the likelihood of dislocation with only a minor decrease in bite force during unilateral biting. By modulating muscle recruitment the animal may be able to maximise bite force whilst minimising the risk of dislocation. PMID:18838138
Hossain, Md Mowrin; Alam, Md Jahangir; Pickering, Mark R; Ward, Thomas; Perriman, Diana; Scarvell, Jennie M; Smith, Paul N
2014-01-01
Total hip arthroplasty or THA is a surgical procedure for the relief of significant disabling pain caused by osteoarthritis or hip fracture. Knowledge of the 3D kinematics of the hip during specific functional activities is important for THA component design. In this paper we compare kinematic measurements obtained by a new 2D-3D registration algorithm with measurements provided by the gold standard roentgen stereo analysis (RSA). The study validates a promising method for investigating the kinematics of some pathologies, which involves fitting three dimensional patient specific 3D CT scans to dynamic fluoroscopic images of the hip during functional activities. This is the first study in which single plane fluoroscopy has been used for kinematic measurements of natural hip bones. The main focus of the study is on the out-of-plane translation and rotation movements which are difficult to measure precisely using a single plane approach. From our experimental results we found that the precision of our proposed approach compares favourably with that of the most recent dual plane fluoroscopy approach. PMID:25571375
Rashev, P Z; Mintchev, M P; Bowes, K L
2000-09-01
The aim of this study was to develop a novel three-dimensional (3-D) object-oriented modeling approach incorporating knowledge of the anatomy, electrophysiology, and mechanics of externally stimulated excitable gastrointestinal (GI) tissues and emphasizing the "stimulus-response" principle of extracting the modeling parameters. The modeling method used clusters of class hierarchies representing GI tissues from three perspectives: 1) anatomical; 2) electrophysiological; and 3) mechanical. We elaborated on the first four phases of the object-oriented system development life-cycle: 1) analysis; 2) design; 3) implementation; and 4) testing. Generalized cylinders were used for the implementation of 3-D tissue objects modeling the cecum, the descending colon, and the colonic circular smooth muscle tissue. The model was tested using external neural electrical tissue excitation of the descending colon with virtual implanted electrodes and the stimulating current density distributions over the modeled surfaces were calculated. Finally, the tissue deformations invoked by electrical stimulation were estimated and represented by a mesh-surface visualization technique. PMID:11026595
NASA Astrophysics Data System (ADS)
Class, G.
1987-07-01
A program to simulate gas motion and shine through of thermal radiation in fusion reactor vacuum flow channels was developed. The inner surface of the flow channel is described by plane areas (triangles, parallelograms) and by surfaces of revolution. By introducing control planes in the flow path, a variance reduction and shortening of the computation, respectively, are achieved through particle splitting and Russian roulette. The code is written in PL/I and verified using published data. Computer aided input of model data is performed interactively either under IBM-TSO or at a microprocessor (IBM PC-AT). The data files are exchangeable between the IBM-mainframe and IBM-PC computers. Both computers can produce plots of the elaborated channel model. For testing, the simulating computation can likewise be run interactively, whereas the production computation can be issued batchwise. The results of code verification are explained, and examples of channel models and of the interactive mode are given.
Eyler, L L; Trent, D S; Budden, M J
1983-09-01
During the course of the TEMPEST computer code development a concurrent effort was conducted to assess the code's performance and the validity of computed results. The results of this work are presented in this document. The principal objective of this effort was to assure the code's computational correctness for a wide range of hydrothermal phenomena typical of fast breeder reactor application. 47 refs., 94 figs., 6 tabs.
ERIC Educational Resources Information Center
Hansen, John A.; Barnett, Michael; Makinster, James G.; Keating, Thomas
2004-01-01
The increased availability of computational modeling software has created opportunities for students to engage in scientific inquiry through constructing computer-based models of scientific phenomena. However, despite the growing trend of integrating technology into science curricula, educators need to understand what aspects of these technologies…
NASA Technical Reports Server (NTRS)
Dulikravich, D. S.
1982-01-01
A fast computer program, GRID3C, was developed to generate multilevel three dimensional, C type, periodic, boundary conforming grids for the calculation of realistic turbomachinery and propeller flow fields. The technique is based on two analytic functions that conformally map a cascade of semi-infinite slits to a cascade of doubly infinite strips on different Riemann sheets. Up to four consecutively refined three dimensional grids are automatically generated and permanently stored on four different computer tapes. Grid nonorthogonality is introduced by a separate coordinate shearing and stretching performed in each of three coordinate directions. The grids are easily clustered closer to the blade surface, the trailing and leading edges and the hub or shroud regions by changing appropriate input parameters. Hub and duct (or outer free boundary) have different axisymmetric shapes. A vortex sheet of arbitrary thickness emanating smoothly from the blade trailing edge is generated automatically by GRID3C. Blade cross sectional shape, chord length, twist angle, sweep angle, and dihedral angle can vary in an arbitrary smooth fashion in the spanwise direction.
Chien, T.H.; Domanus, H.M.; Sha, W.T.
1993-02-01
The COMMIX-PPC computer program is an extended and improved version of earlier COMMIX codes and is specifically designed for evaluating the thermal performance of power plant condensers. The COMMIX codes are general-purpose computer programs for the analysis of fluid flow and heat transfer in complex industrial systems. In COMMIX-PPC, two major features have been added to previously published COMMIX codes. One feature is the incorporation of one-dimensional conservation of mass. momentum, and energy equations on the tube side, and the proper accounting for the thermal interaction between shell and tube side through the porous medium approach. The other added feature is the extension of the three-dimensional conservation equations for shell-side flow to treat the flow of a multicomponent medium. COMMIX-PPC is designed to perform steady-state and transient three-dimensional analysis of fluid flow with heat transfer in a power plant condenser. However, the code is designed in a generalized fashion so that, with some modification. it can be used to analyze processes in any heat exchanger or other single-phase engineering applications.
Chien, T.H.; Domanus, H.M.; Sha, W.T.
1993-02-01
The COMMIX-PPC computer pregrain is an extended and improved version of earlier COMMIX codes and is specifically designed for evaluating the thermal performance of power plant condensers. The COMMIX codes are general-purpose computer programs for the analysis of fluid flow and heat transfer in complex Industrial systems. In COMMIX-PPC, two major features have been added to previously published COMMIX codes. One feature is the incorporation of one-dimensional equations of conservation of mass, momentum, and energy on the tube stile and the proper accounting for the thermal interaction between shell and tube side through the porous-medium approach. The other added feature is the extension of the three-dimensional conservation equations for shell-side flow to treat the flow of a multicomponent medium. COMMIX-PPC is designed to perform steady-state and transient. Three-dimensional analysis of fluid flow with heat transfer tn a power plant condenser. However, the code is designed in a generalized fashion so that, with some modification, it can be used to analyze processes in any heat exchanger or other single-phase engineering applications. Volume I (Equations and Numerics) of this report describes in detail the basic equations, formulation, solution procedures, and models for a phenomena. Volume II (User`s Guide and Manual) contains the input instruction, flow charts, sample problems, and descriptions of available options and boundary conditions.
Olubamiji, Adeola D; Izadifar, Zohreh; Zhu, Ning; Chang, Tuanjie; Chen, Xiongbiao; Eames, B Frank
2016-05-01
Synchrotron radiation inline phase-contrast imaging combined with computed tomography (SR-inline-PCI-CT) offers great potential for non-invasive characterization and three-dimensional visualization of fine features in weakly absorbing materials and tissues. For cartilage tissue engineering, the biomaterials and any associated cartilage extracellular matrix (ECM) that is secreted over time are difficult to image using conventional absorption-based imaging techniques. For example, three-dimensional printed polycaprolactone (PCL)/alginate/cell hybrid constructs have low, but different, refractive indices and thicknesses. This paper presents a study on the optimization and utilization of inline-PCI-CT for visualizing the components of three-dimensional printed PCL/alginate/cell hybrid constructs for cartilage tissue engineering. First, histological analysis using Alcian blue staining and immunofluorescent staining assessed the secretion of sulfated glycosaminoglycan (GAGs) and collagen type II (Col2) in the cell-laden hybrid constructs over time. Second, optimization of inline PCI-CT was performed by investigating three sample-to-detector distances (SDD): 0.25, 1 and 3 m. Then, the optimal SDD was utilized to visualize structural changes in the constructs over a 42-day culture period. The results showed that there was progressive secretion of cartilage-specific ECM by ATDC5 cells in the hybrid constructs over time. An SDD of 3 m provided edge-enhancement fringes that enabled simultaneous visualization of all components of hybrid constructs in aqueous solution. Structural changes that might reflect formation of ECM also were evident in SR-inline-PCI-CT images. Summarily, SR-inline-PCI-CT images captured at the optimized SDD enables visualization of the different components in hybrid cartilage constructs over a 42-day culture period. PMID:27140161
Nevins, Marc L; Camelo, Marcelo; Rebaudi, Alberto; Lynch, Samuel E; Nevins, Myron
2005-08-01
This study utilized three-dimensional micro-computed tomography (micro-CT) to evaluate the regenerative response to Bio-Oss Collagen when used alone or in combination with a Bio-Gide bilayer collagen membrane for the treatment of four intrabony defects (5 to 7 mm) around single-rooted teeth. The micro-CT observations are compared to the clinical, radiographic, and histologic results, which have been previously reported. After reflecting a full-thickness flap, thorough degranulation and root planing were accomplished. Bio-Oss Collagen was then used to fill the defects, and in two cases a Bio-Gide membrane was placed over the filled defect. Radiographs, clinical probing depths, and attachment levels were obtained before treatment and immediately preceding en bloc resection of teeth and surrounding tissues 9 months later. A mean pocket depth reduction of 5.75 mm and mean clinical attachment level gain of 5.25 mm were recorded. The histologic evaluation demonstrated the formation of a complete new attachment apparatus with new cementum, periodontal ligament, and alveolar bone at the level of and coronal to the calculus reference notch. Micro-CT evaluation confirmed the histologic results and demonstrated the absence of ankylosis or root resorption for all specimens. This human histologic study demonstrated that Bio-Oss Collagen has the capacity to facilitate regeneration of the periodontal attachment apparatus when placed in intrabony defects. Micro-CT observations confirmed the histologic results and enhanced the three-dimensional understanding of periodontal wound healing. The results indicate that micro-CT may be useful for three-dimensional evaluation of periodontal regenerative procedures. PMID:16089044
Melcher, A H; Holowka, S; Pharoah, M; Lewin, P K
1997-07-01
A second CT scan of the mummy Djedmaatesankh, which is housed in the Royal Ontario Museum, Toronto, Ontario, has been undertaken after an interval of some 15 years. The image data set of her dentition and the associated tissues acquired from 3 mm thick x 3 mm spacing slices was transferred to an ISG Allegro work station where two-dimensional reformats and three-dimensional reconstructions were produced. This non-invasive examination provided information on dental disease that is, in a number of respects, an advance on that which previously could be obtained from mummies by the traditional methods of visual inspection after unwrapping and by two-dimensional radiography. The two- and three-dimensional images reveal that: three molars are missing and the right maxillary canine is impacted; the rest of the dentition is afflicted by severe attrition, caries and periodontal disease; and, of the 28 teeth present in the mouth, 24 exhibit exposure of their dental pulps and 18 are afflicted by periapical lesions including five that could have contributed to a large secondarily infected radicular cyst. The cyst have displaced the maxillary antrum and enlarged the maxilla on its lateral aspect and the vault of the palate on its medial aspect. Pus from the cyst may have drained through five different sinuses. In life, Djedmaatesankh's widespread dental infection probably caused her considerable pain, personal distress and malaise, and possibly resulted in her death. PMID:9261496
NASA Technical Reports Server (NTRS)
Thompson, D.; Mogili, P.; Chalasani, S.; Addy, H.; Choo, Y.
2004-01-01
Steady-state solutions of the Reynolds-averaged Navier-Stokes (RANS) equations were computed using the Colbalt flow solver for a constant-section, rectangular wing based on an extruded two-dimensional glaze ice shape. The one equation Spalart-Allmaras turbulence model was used. The results were compared with data obtained from a recent wind tunnel test. Computed results indicate that the steady RANS solutions do not accurately capture the recirculating region downstream of the ice accretion, even after a mesh refinement. The resulting predicted reattachment is farther downstream than indicated by the experimental data. Additionally, the solutions computed on a relatively coarse baseline mesh had detailed flow characteristics that were different from those computed on the refined mesh or the experimental data. Steady RANS solutions were also computed to investigate the effects of spanwise variation in the ice shape. The spanwise variation was obtained via a bleeding function that merged the ice shape with the clean wing using a sinusoidal spanwise variation. For these configurations, the results predicted for the extruded shape provided conservative estimates for the performance degradation of the wing. Additionally, the spanwise variation in the ice shape and the resulting differences in the flow fields did not significantly change the location of the primary reattachment.
Three-dimensional sonoembryology.
Benoit, Bernard; Hafner, Tomislav; Kurjak, Asim; Kupesić, Sanja; Bekavac, Ivanka; Bozek, Tomislav
2002-01-01
Three-dimensional (3D) ultrasound plays an important role in obstetrics, predominantly for assessing fetal anatomy. Presenting volume data in a standard anatomic orientation valuably assists both ultrasonographers and pregnant patients to recognize the anatomy more readily. Three-dimensional ultrasound is advantageous in studying normal embryonic and/or fetal development, as well as providing information for families at risk for specific congenital anomalies by confirming normality. This method offers advantages in assessing the embryo in the first trimester due to its ability to obtain multiplanar images through endovaginal volume acquisition. Rotation allows the systematic review of anatomic structures and early detection of fetal anomalies. Three-dimensional ultrasound imaging in vivo compliments pathologic and histologic evaluation of the developing embryo, giving rise to a new term: 3D sonoembryology. Rapid technological development will allow real-time 3D ultrasound to provide improved and expanded patient care on the one side, and increased knowledge of developmental anatomy on the other. PMID:11933658
Three-dimensional coronary angiography
NASA Astrophysics Data System (ADS)
Suurmond, Rolf; Wink, Onno; Chen, James; Carroll, John
2005-04-01
Three-Dimensional Coronary Angiography (3D-CA) is a novel tool that allows clinicians to view and analyze coronary arteries in three-dimensional format. This will help to find accurate length estimates and to find the optimal viewing angles of a lesion based on the three-dimensional vessel orientation. Various advanced algorithms are incorporated in this 3D processing utility including 3D-RA calibration, ECG phase selection, 2D vessel extraction, and 3D vessel modeling into a utility with optimized workflow and ease-of-use features, which is fully integrated in the environment of the x-ray catheterization lab. After the 3D processing, the 3D vessels can be viewed and manipulated interactively inside the operating room. The TrueView map provides a quick overview of gantry angles with optimal visualization of a single or bifurcation lesion. Vessel length measurements can be performed without risk of underestimating a vessel segment due to foreshortening. Vessel cross sectional diameters can also be measured. Unlike traditional, projection-based quantitative coronary analysis, the additional process of catheter calibration is not needed for diameter measurements. Validation studies show a high reproducibility of the measurements, with little user dependency.
Erkmen, E; Simşek, B; Yücel, E; Kurt, A
2005-07-01
The purpose of this study was to evaluate the mechanical behavior of different fixation methods used in bilateral sagittal split ramus osteotomy (BSSRO). Part 1 comprises of the results of the analysis for mandibular advancement, four different fixation configurations of six hole fragmentation mini plates with monocortical screws and lag screws and posterior loading conditions in the molar and premolar region. The finite element analysis method (FEA) appears suitable for simulating complex mechanical stress situations in the maxillofacial region. The mechanical behavior of selected lag screws with linear or triangular configuration and double parallel or single oblique six hole mini plates with monocortical screws were compared by FEA after 5 mm BSSRO advancement procedure. Four separate three-dimensional finite element models of the mandible were created to simulate the BSSRO and corresponding fixation methods. These models consisted of 122,717 elements and 25,048 nodes. The mechanical parameters of the materials studied were adopted from the literature or were based on manufacturer's information. 500 N posterior occlusal loads were simulated on the distal segments. The commercial finite element solver MSC Marc software was utilized to calculate the stress fields on both the segments and fixative appliances. It was concluded that the use of 2.0mm lag screws placed in a triangular configuration following the BSSRO advancement surgery provides sufficient stability with any rotational movement and less stress fields at the osteotomy site, when compared with the other rigid fixation methods used in the current study. PMID:16053877
NASA Technical Reports Server (NTRS)
Leonard, A.
1980-01-01
Three recent simulations of tubulent shear flow bounded by a wall using the Illiac computer are reported. These are: (1) vibrating-ribbon experiments; (2) study of the evolution of a spot-like disturbance in a laminar boundary layer; and (3) investigation of turbulent channel flow. A number of persistent flow structures were observed, including streamwise and vertical vorticity distributions near the wall, low-speed and high-speed streaks, and local regions of intense vertical velocity. The role of these structures in, for example, the growth or maintenance of turbulence is discussed. The problem of representing the large range of turbulent scales in a computer simulation is also discussed.
Lai, Jyh-Mirn; Wu, Jui-Te; Yang, Wei-Cheng; Chao, Ming-Hsin; Nagahata, Hajime
2016-05-01
A two-day-old female Toggenburg goat with thoracic ectopia cordis (EC) was diagnosed via radiography and computed tomography. The goat was born with EC, defects of the sternum and a supra-umbilical abdominal wall, but without the presence of Cantrell's syndrome. Necropsy and histopathological findings indicated the affected kid had malformation of the heart with an enlarged left ventricle. The findings showed the heart (9 x 5 x 5 cm) stayed outside the thorax, and was covered by a semitransparent membrane. This report is the first to describe a case of thoracic EC in a goat whose sternum was not developed fully and was not connected to the ribs. It is also the first paper to describe three-dimensional images of this condition constructed from computed tomography scans. PMID:27506092
Technology Transfer Automated Retrieval System (TEKTRAN)
High resolution x-ray computed tomography (HRCT) is a non-destructive diagnostic imaging technique with sub-micron resolution capability that is now being used to evaluate the structure and function of plant xylem network in three dimensions (3D). HRCT imaging is based on the same principles as medi...
ERIC Educational Resources Information Center
Ruddick, Kristie R.; Parrill, Abby L.; Petersen, Richard L.
2012-01-01
In this study, a computational molecular orbital theory experiment was implemented in a first-semester honors general chemistry course. Students used the GAMESS (General Atomic and Molecular Electronic Structure System) quantum mechanical software (as implemented in ChemBio3D) to optimize the geometry for various small molecules. Extended Huckel…
Portaluri, Maurizio . E-mail: portaluri@hotmail.com; Fucilli, Fulvio I.M.; Castagna, Roberta; Bambace, Santa; Pili, Giorgio; Tramacere, Francesco; Russo, Donatella; Francavilla, Maria Carmen
2006-11-15
Purpose: To evaluate the dosimetric parameters of three-dimensional conformal radiotherapy (3D-CRT) in locally advanced head-and-neck tumors (Stage II and above) and the effects on xerostomia. Methods and Materials: A total of 49 patients with histologically proven squamous cell cancer of the head and neck were consecutively treated with 3D-CRT using a one-point setup technique; 17 had larynx cancer, 12 oropharynx, 12 oral cavity, and 6 nasopharynx cancer; 2 had other sites of cancer. Of the 49 patients, 41 received postoperative RT and 8 definitive treatment. Also, 13 were treated with cisplatin-based chemotherapy before and during RT; in 6 cases, 5-fluorouracil was added. The follow-up time was 484-567 days (median, 530 days). Results: One-point setup can deliver 96% of the prescribed dose to the isocenter, to the whole planning target volume, including all node levels of the neck and without overdosages. The mean dose to the primary planning target volume was 49.54 {+-} 4.82 Gy (51.53 {+-} 5.47 Gy for larynx cases). The average dose to the contralateral parotid gland was approximately 38 Gy (30 Gy for larynx cases). The maximal dose to the spinal cord was 46 Gy. A Grade 0 Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer xerostomia score corresponded to a mean dose of 30 Gy to one parotid gland. A lower xerostomia score with a lower mean parotid dose and longer follow-up seemed to give rise to a sort of functional recovery phenomenon. Conclusion: Three dimensional-CRT in head-and-neck cancers permits good coverage of the planning target volume with about 10-11 segments and one isocenter. With a mean dose of approximately 30 Gy to the contralateral parotid, we observed no or mild xerostomia.
Bowman, S. M.; Gill, D. F.
2006-07-01
The isotopic depletion capabilities of the new Standardized Computer Analyses for Licensing Evaluation control module TRITON, coupled with ORIGEN-S, were evaluated using spent fuel assays from several commercial light water reactors with both standard and mixed-oxide fuel assemblies. Calculations were performed using the functional modules NEWT and KENO-VI. NEWT is a two-dimensional, arbitrary-geometry, discrete-ordinates transport code, and KENO-VI is a three-dimensional Monte Carlo transport code capable of handling complex three-dimensional geometries. To validate the codes and data used in depletion calculations, numerical predictions were compared with experimental measurements for a total of 29 samples taken from the Calvert Cliffs, Obrigheim, and San Onofre pressurized water reactors and the Gundremmingen boiling water reactor. Similar comparisons have previously been performed at the Oak Ridge National Laboratory for the one-dimensional SAS2H control module. The SAS2H, TRITON/KENO-VI, and TRITON/NEWT results were compared for corresponding samples. All analyses showed that TRITON/KENO-VI and TRITON/NEWT produced typically similar or better results than SAS2H. The calculations performed in this validation study demonstrate that the depletion capabilities of TRITON accurately model spent fuel depletion and decay. (authors)
Daniels, Jeffrey J.
1977-01-01
Three-dimensional induced polarization and resistivity modeling for buried electrode configurations can be achieved by adapting surface integral techniques for surface electrode configurations to buried electrodes. Modification of. the surface technique is accomplished by considering the additional mathematical terms required to express-the changes in the electrical potential and geometry caused by placing the source and receiver electrodes below the surface. This report presents a listing of a computer program to calculate the resistivity and induced polarization response from a three-dimensional body for buried electrode configurations. The program is designed to calculate the response for the following electrode configurations: (1) hole-to-surface array with a buried bipole source and a surface bipole receiver, (2) hole-to-surface array with a buried pole source and a surface bipole receiver, (3) hole-to-hole array with a buried, fixed pole source and a moving bipole receiver, (4) surface-to-hole array with a fixed pole source on the surface and a moving bipole receiver in the borehole, (5) hole-to-hole array with a buried, fixed bipole source and a buried, moving bipole receiver, (6) hole-to-hole array with a buried, moving bipole source and a buried, moving bipole receiver, and (7) single-hole, buried bipole-bipole array. Input and output examples are given for each of the arrays.
NASA Technical Reports Server (NTRS)
Tezduyar, Tayfun E.
1998-01-01
This is a final report as far as our work at University of Minnesota is concerned. The report describes our research progress and accomplishments in development of high performance computing methods and tools for 3D finite element computation of aerodynamic characteristics and fluid-structure interactions (FSI) arising in airdrop systems, namely ram-air parachutes and round parachutes. This class of simulations involves complex geometries, flexible structural components, deforming fluid domains, and unsteady flow patterns. The key components of our simulation toolkit are a stabilized finite element flow solver, a nonlinear structural dynamics solver, an automatic mesh moving scheme, and an interface between the fluid and structural solvers; all of these have been developed within a parallel message-passing paradigm.
NASA Astrophysics Data System (ADS)
Wu, Yuqi; Cai, Xiao-Chuan
2014-02-01
Due to the rapid advancement of supercomputing hardware, there is a growing interest in parallel algorithms for modeling the full three-dimensional interaction between the blood flow and the arterial wall. In [4], Barker and Cai developed a parallel framework for solving fluid-structure interaction problems in two dimensions. In this paper, we extend the idea to three dimensions. We introduce and study a parallel scalable domain decomposition method for solving nonlinear monolithically coupled systems arising from the discretization of the coupled system in an arbitrary Lagrangian-Eulerian framework with a fully implicit stabilized finite element method. The investigation focuses on the robustness and parallel scalability of the Newton-Krylov algorithm preconditioned with an overlapping additive Schwarz method. We validate the proposed approach and report the parallel performance for some patient-specific pulmonary artery problems. The algorithm is shown to be scalable with a large number of processors and for problems with millions of unknowns.
Takemura, Yukihiko; Hanaoka, Koji; Kawamata, Ryota; Sakurai, Takashi; Teranaka, Toshio
2014-01-01
The polymerization shrinkage of flowable resin composites was evaluated using air bubbles as traceable markers. Three different surface treatments i.e. an adhesive silane coupling agent, a separating silane coupling agent, and a combination of both, were applied to standard cavities. Before and after polymerization, X-ray micro-computed tomography images were recorded. Their superimposition and comparison allowed position changes of the markers to be visualized as vectors. The movement of the markers in the resin composite was, therefore, quantitatively evaluated from the tomographic images. Adhesion was found to significantly influence shrinkage patterns. The method used here could be employed to visualize shrinkage vectors and shrinkage volume. PMID:24988881
NASA Astrophysics Data System (ADS)
Nejadmalayeri, Alireza; Vezolainen, Alexei; Vasilyev, Oleg V.
2011-11-01
With the recent development of parallel adaptive wavelet collocation method, adaptive numerical simulations of high Reynolds number turbulent flows have become feasible. The integration of turbulence modeling of different fidelity with adaptive wavelet methods results in a hierarchical approach for modeling and simulating turbulent flows in which all or most energetic parts of coherent eddies are dynamically resolved on self-adaptive computational grids, while modeling the effect of the unresolved incoherent or less energetic modes. This talk is the first attempt to estimate how spatial modes of both Coherent Vortex Simulations (CVS) and Stochastic Coherent Adaptive Large Eddy Simulations (SCALES) scale with Reynolds number. The computational complexity studies for both CVS and SCALES of linearly forced homogeneous turbulence are performed at effective non-adaptive resolutions of 2563, 5123, 10243, and 20483 corresponding to approximate Reλ of 70, 120, 190, 320. The details of the simulations are discussed and the results of compression achieved by CVS and SCALES as well as scalability studies of the parallel algorithm for the aforementioned Taylor micro-scale Reynolds numbers are presented. This work was supported by NSF under grant No. CBET-0756046.
Hyun, Joo-Bong; Hwang, Dong-Choon; Shin, Dong-Hak; Kim, Eun-Soo
2007-11-01
A novel curved computational integral imaging reconstruction (C-CIIR) technique for the virtually curved integral imaging (VCII) system is proposed, and its performances are analyzed. In the C-CIIR model, an additional virtual large-aperture lens is included to provide a multidirectional curving effect in the reconstruction process, and its effect is analyzed in detail by using the ABCD matrix. With this method, resolution-enhanced 3D object images can be computationally reconstructed from the picked-up elemental images of the VCII system. To confirm the feasibility of the proposed model, some experiments are carried out. Experiments revealed that the sampling rate in the VCII system could be kept at a maximum value within some range of the distance z, whereas in the conventional integral imaging system it linearly decreased as the distance z increased. It is also shown that resolutions of the object images reconstructed by the C-CIIR method have been significantly improved compared with those of the conventional CIIR method. PMID:17973014
Hyder, M.L.; Farawila, Y.M.; Abdel-Khalik, S.I.; Halvorson, P.J.
1992-05-01
In the development of the Severe Accident Analysis Program for the Savannah River production reactors, it was recognized that certain accidents have the potential for causing damaging steam explosions. The massive SRS reactor buildings are likely to withstand any imaginable steam explosion. However, reactor components and building structures including hatches, ventilation ducts, etc., could be at risk if such an explosion occurred. No tools were available to estimate the effects of such explosions on actual structures. To meet this need, the Savannah River Laboratory contracted with the Georgia Institute of Technology Research Institute for development of a computer-based calculational tool for estimating the effects of steam explosions. The goal for this study was to develop a computer code that could be used parametrically to predict the effects of various steam explosions on their surroundings. This would be able to predict whether a steam explosion of a given magnitude would be likely to fail a particular structure. This would require, of course, that the magnitude of the explosion be specified through some combination of judgment and calculation. The requested code, identified as the K-FIX(GT) code, was developed and delivered by the contractor, along with extensive documentation. The several individual reports that constitute the documentation are each being issued as a separate WSRC report. Documentation includes several model calculations, and representation of these in graphic form. This report gives detailed instructions for the use of the code, including identification of all input parameters required.
NASA Technical Reports Server (NTRS)
Iyer, Venkit
1990-01-01
A solution method, fourth-order accurate in the body-normal direction and second-order accurate in the stream surface directions, to solve the compressible 3-D boundary layer equations is presented. The transformation used, the discretization details, and the solution procedure are described. Ten validation cases of varying complexity are presented and results of calculation given. The results range from subsonic flow to supersonic flow and involve 2-D or 3-D geometries. Applications to laminar flow past wing and fuselage-type bodies are discussed. An interface procedure is used to solve the surface Euler equations with the inviscid flow pressure field as the input to assure accurate boundary conditions at the boundary layer edge. Complete details of the computer program used and information necessary to run each of the test cases are given in the Appendix.
Ishay, Yakir; Leviatan, Yehuda; Bartal, Guy
2014-05-15
We present a semi-analytical method for computing the electromagnetic field in and around 3D nanoparticles (NP) of complex shape and demonstrate its power via concrete examples of plasmonic NPs that have nonsymmetrical shapes and surface areas with very small radii of curvature. In particular, we show the three axial resonances of a 3D cashew-nut and the broadband response of peanut-shell NPs. The method employs the source-model technique along with a newly developed intricate source distributing algorithm based on the surface curvature. The method is simple and can outperform finite-difference time domain and finite-element-based software tools in both its efficiency and accuracy. PMID:24978226
NASA Technical Reports Server (NTRS)
Lin, S. J.; Kreskovsky, J. P.; Briley, W. R.; Mcdonald, H.
1983-01-01
Procedure for computing subsonic, turbulent flow in turbofan lobe mixers was extended to allow consideration of flow fields in which a swirl component of velocity may be present. Additional, an optional k-lambda turbulence model was added to the procedure. The method of specifying the initial flow field was also modified, allowing parametric specification or radial secondary flow velocities, and making it possible to consider initial flow fields which have significant inlet secondary flow vorticity. A series of example calculations was performed which demonstrate the various capabilities of the modified code. These calculations demonstrate the effects of initial secondary flows of various magnitudes, the effects of swirl, and the effects of turbulence model on the mixing process. The results of these calculations indicate that the initial secondary flows, presumed to be generated within the lobes, play a dominant role in the mixing process, and that the predicted results are relatively insensitive to the turbulence model used.
NASA Technical Reports Server (NTRS)
Kaiser, Mary K.; Montegut, Michael J.; Proffitt, Dennis R.
1995-01-01
The motion of objects during motion parallax can be decomposed into 2 observer-relative components: translation and rotation. The depth ratio of objects in the visual field is specified by the inverse ratio of their angular displacement (from translation) or equivalently by the inverse ratio of their rotations. Despite the equal mathematical status of these 2 information sources, it was predicted that observers would be far more sensitive to the translational than rotational component. Such a differential sensitivity is implicitly assumed by the computer graphics technique billboarding, in which 3-dimensional (3-D) objects are drawn as planar forms (i.e., billboards) maintained normal to the line of sight. In 3 experiments, observers were found to be consistently less sensitive to rotational anomalies. The implications of these findings for kinetic depth effect displays and billboarding techniques are discussed.
Guo, Weixing; Langevin, C.D.
2002-01-01
This report documents a computer program (SEAWAT) that simulates variable-density, transient, ground-water flow in three dimensions. The source code for SEAWAT was developed by combining MODFLOW and MT3DMS into a single program that solves the coupled flow and solute-transport equations. The SEAWAT code follows a modular structure, and thus, new capabilities can be added with only minor modifications to the main program. SEAWAT reads and writes standard MODFLOW and MT3DMS data sets, although some extra input may be required for some SEAWAT simulations. This means that many of the existing pre- and post-processors can be used to create input data sets and analyze simulation results. Users familiar with MODFLOW and MT3DMS should have little difficulty applying SEAWAT to problems of variable-density ground-water flow.
Guyot, Y; Luyten, F P; Schrooten, J; Papantoniou, I; Geris, L
2015-12-01
Bone tissue engineering strategies use flow through perfusion bioreactors to apply mechanical stimuli to cells seeded on porous scaffolds. Cells grow on the scaffold surface but also by bridging the scaffold pores leading a fully filled scaffold following the scaffold's geometric characteristics. Current computational fluid dynamic approaches for tissue engineering bioreactor systems have been mostly carried out for empty scaffolds. The effect of 3D cell growth and extracellular matrix formation (termed in this study as neotissue growth), on its surrounding fluid flow field is a challenge yet to be tackled. In this work a combined approach was followed linking curvature driven cell growth to fluid dynamics modeling. The level-set method (LSM) was employed to capture neotissue growth driven by curvature, while the Stokes and Darcy equations, combined in the Brinkman equation, provided information regarding the distribution of the shear stress profile at the neotissue/medium interface and within the neotissue itself during growth. The neotissue was assumed to be micro-porous allowing flow through its structure while at the same time allowing the simulation of complete scaffold filling without numerical convergence issues. The results show a significant difference in the amplitude of shear stress for cells located within the micro-porous neo-tissue or at the neotissue/medium interface, demonstrating the importance of taking along the neotissue in the calculation of the mechanical stimulation of cells during culture.The presented computational framework is used on different scaffold pore geometries demonstrating its potential to be used a design as tool for scaffold architecture taking into account the growing neotissue. Biotechnol. Bioeng. 2015;112: 2591-2600. © 2015 Wiley Periodicals, Inc. PMID:26059101
Three-dimensional metamaterials
Burckel, David Bruce
2012-06-12
A fabrication method is capable of creating canonical metamaterial structures arrayed in a three-dimensional geometry. The method uses a membrane suspended over a cavity with predefined pattern as a directional evaporation mask. Metallic and/or dielectric material can be evaporated at high vacuum through the patterned membrane to deposit resonator structures on the interior walls of the cavity, thereby providing a unit cell of micron-scale dimension. The method can produce volumetric metamaterial structures comprising layers of such unit cells of resonator structures.
Three-dimensional image signals: processing methods
NASA Astrophysics Data System (ADS)
Schiopu, Paul; Manea, Adrian; Craciun, Anca-Ileana; Craciun, Alexandru
2010-11-01
Over the years extensive studies have been carried out to apply coherent optics methods in real-time processing, communications and transmission image. This is especially true when a large amount of information needs to be processed, e.g., in high-resolution imaging. The recent progress in data-processing networks and communication systems has considerably increased the capacity of information exchange. We describe the results of literature investigation research of processing methods for the signals of the three-dimensional images. All commercially available 3D technologies today are based on stereoscopic viewing. 3D technology was once the exclusive domain of skilled computer-graphics developers with high-end machines and software. The images capture from the advanced 3D digital camera can be displayed onto screen of the 3D digital viewer with/ without special glasses. For this is needed considerable processing power and memory to create and render the complex mix of colors, textures, and virtual lighting and perspective necessary to make figures appear three-dimensional. Also, using a standard digital camera and a technique called phase-shift interferometry we can capture "digital holograms." These are holograms that can be stored on computer and transmitted over conventional networks. We present some research methods to process "digital holograms" for the Internet transmission and results.
NASA Astrophysics Data System (ADS)
Hammon, William S., III
The life cycle of a seismic data volume can be broken into three parts: acquisition, processing, and interpretation. Accomplishing each of these steps requires the application of a different set of skills and techniques to accomplish. Of the three, data acquisition and processing are the most expensive steps to perform. Data acquisition is a time and equipment intensive operation. Processing the seismic data, after acquisition, is a computationally very expensive procedure; usually performed on very large computer clusters. However, the most time consuming of these steps is the interpretation of the seismic data. Arguably, this is also the least optimized part of the volume life cycle, as certain aspects of interpretation are still performed largely by hand. Efficiency gains are ongoing in the fields of seismic acquisition and processing (especially migration). Initial steps have also been made in the semi-automation of interpretation, but much work remains to be done. Semi-automatic interpretation holds the greatest promise for quickly improving the value of the seismic volume acquisition and utilization cycle. This dissertation concentrates on the development of new techniques to aid the human interpreter in their interpretation of 3D seismic volumes. The ability to both accelerate and improve interpretation of geology in a data volume is a significant goal for increasing the value realized from a given data set. Particular attention is given to two of the more intractable problems in seismic data interpretation: salt-body delineation, and the interpretation of stratigraphic features. The difficulties inherent in each task are different, but both tasks are quite time consuming when performed largely by hand. This dissertation is comprised of five parts. Part 1 describes Voxel Density, a novel volume processing technique that can be used to filter, or improve the contrast in a data set. This technique uses the local persistence of features in the data set to
NASA Astrophysics Data System (ADS)
Iizuka, Keigo
2003-08-01
It was experimentally verified that an ordinary 25-μm-thick cellophane sheet possesses properties of a wide wavelength spectrum half-wave plate. Moreover, cellophane displayed superior performance when used for rotating the direction of polarization of white light than a commercially available half-wave plate with a specified wavelength. The retardance of the cellophane was measured to be 170°. The availability of a half-wave plate of an extra large size with low cost opens up usages for large size displays. As an example of its application, an ordinary screen of a laptop personal computer was converted into that of a three-dimensional display by the cellophane half-wave plate. It may be added that the price per square cm2 of the cellophane half-wave plate is about 1/3500 of that of a commercially available half-wave plate.
Wang, C.Y.
1985-01-01
A three-dimensional computer program for linear/non-linear, static/dynamic analyses of reactor-piping systems under various accident loads is described. In the analysis, the hydrodynamic calculation can be performed in the implicit or semi-implicit manner. The structure response can be calculated using either a purely explicit or implicit time-integration scheme. Coupling between the fluid and structure is achieved by utilizing either the implicit-explicit or implicit-implicit link. Thus, a wide range of piping safety problems can be analyzed by the suitable choice of options available in the hydrodynamics and structural analysis. In this paper, several salient features are presented. Sample problems illustrating the versatility of the program are given. The results are discussed in detail.
Hayakawa, Yoshihiko; Yamamoto, Kazuhiro; Kousuge, Yuji; Kobayashi, Norio; Wakoh, Mamoru; Sekiguchi, Hiroshi; Yakushiji, Masashi; Farman, Allan G
2003-08-01
Based on technical studies and clinical examinations, the clinical value of a new three-dimensional dento-alveolar imaging system, Tuned-Aperture Computed Tomography (TACT), were examined for dental applications. TACT is a conventional and low-cost tomosynthesis method in which the benefit of digitization is fully utilized. The clinical information yield of TACT has been examined for the detection of dental caries, periodontal defects and radicular fractures, and also for the pre-surgical assessment of implant placement and impacted teeth. In this article, we introduce basic TACT technology, review the literature pertaining to in vitro and in vivo studies, and describe the outline of our study of TACT to determine its clinical value in the assessment of impacted maxillary teeth. PMID:14694831
NASA Astrophysics Data System (ADS)
Pauchard, Yves; Ayres, Fábio J.; Boyd, Steven K.
2011-10-01
Subject motion during acquisition of high-resolution peripheral quantitative computed tomography (HR-pQCT) results in image artifacts and interferes with quantification of bone architecture used to study bone-related diseases such as osteoporosis. We propose an automatic method to measure physical subject motion that frequently takes place during acquisition. Three measures derived from projection data are proposed to quantify motion artifacts: in-plane translation (εT) and in-plane rotation (εR) utilizing projection moments and longitudinal translation (εz) based on tracking projection profiles. Validation was performed using a phantom containing sections of distal human cadaver radii attached to a mechanical device to precisely control in-plane rotation and longitudinal translation that was intentionally performed during HR-pQCT data acquisition. Motion measured by the new automated technique was compared to the known applied motion, and related to percent errors in morphological parameters quantifying bone properties. It was determined that of the three proposed measures, εT best captured a quantified representation of image quality. εT linearly relates to true physical in-plane translational motion (r2 = 0.95, p<0.001) and is independent from longitudinal translational motion as well as the object being scanned. Additionally, εz captures large longitudinal movements and combines well with εT to fully characterize physical motion artifacts. The magnitude of εT corresponds to morphological parameter error and is an excellent basis to select high-quality images. Morphological parameter errors from these experiments confirmed our earlier computer simulations which showed that increased subject motion resulted in artificially higher trabecular number, and artificially lower bone mineral density and cortical thickness. The magnitude and, notably, the uncertainty of the morphological errors increased with increased physical motion, and this impedes a direct
Jorgensen,S.; Eaker, D.; Vercnocke, A.; Ritman, E.
2008-01-01
Variation in computed tomography (CT) image grayscale and spatial geometry due to specimen orientation, magnification, voxel size, differences in X-ray photon energy and limited field-of-view during the scan, were evaluated in repeated micro-CT scans of iliac crest biopsies and test phantoms. Using the micro-CT scanner on beamline X2B at the Brookhaven National Laboratory's National Synchrotron Light Source, 3-D micro-CT images were generated. They consisted of up to 1024 X 24002, 4-mum cubic voxels, each with 16-bit gray-scale. We also reconstructed the images at 16-, 32-, and 48-mum voxel resolution. Scan data were reconstructed from the complete profiles using filtered back-projection and from truncated profiles using profile-extension and with a Local reconstruction algorithm. Three biopsies and one bonelike test phantom were each rescanned at three different times at annual intervals. For the full-data-set reconstructions, the reproducibility of the estimates of mineral content of bone at mean bone opacity value, was {+-}28.8 mg/cm3, i.e., 2.56%, in a 4-mum cubic voxel at the 95% confidence level. The reproducibility decreased with increased voxel size. The interscan difference in imaged bone volume ranged from 0.86 {+-} 0.64% at 4-mum voxel resolution, and 2.64 {+-} 2.48% at 48 mum.
NASA Astrophysics Data System (ADS)
Hieber, Simone E.; Khimchenko, Anna; Kelly, Christopher; Mariani, Luigi; Thalmann, Peter; Schulz, Georg; Schmitz, Rüdiger; Greving, Imke; Dominietto, Marco; Müller, Bert
2014-09-01
Hippocampal sclerosis is a common cause of epilepsy, whereby a neuronal cell loss of more than 50% cells is characteristic. If medication fails the best possible treatment is the extraction of the diseased organ. To analyze the microanatomy of the diseased tissue we scanned a human hippocampus extracted from an epilepsy patient. After the identification of degenerated tissue using magnetic resonance imaging the specimen was reduced in size to fit into a cylindrical container with a diameter of 6 mm. Using synchrotron radiation and grating interferometry we acquired micro computed tomography datasets of the specimen. The present study was one of the first successful phase tomography measurements at the imaging beamline P05 (operated by HZG at the PETRA III storage ring, DESY, Hamburg, Germany). Ring and streak artefacts were reduced by enhanced flat-field corrections, combined wavelet-Fourier filters and bilateral filtering. We improved the flat-field correction by the consideration of the correlation between the projections and the flat-field images. In the present study, the correlation that was based on mean squared differences and evaluated on manually determined reference regions leads to the best artefact reduction. A preliminary segmentation of the abnormal tissue reveals that a clinically relevant study requires the development of even more sophisticated artifact reduction tools or a phase contrast measurement of higher quality.
NASA Astrophysics Data System (ADS)
Kondo, Norio
2014-07-01
It is well known from a lot of experimental data that fluid forces acting on two tandem circular cylinders are quite different from those acting on a single circular cylinder. Therefore, we first present numerical results for fluid forces acting on two tandem circular cylinders, which are mounted at various spacings in a smooth flow, and second we present numerical results for flow-induced vibrations of the upstream circular cylinder in the tandem arrangement. The two circular cylinders are arranged at close spacing in a flow field. The upstream circular cylinder is elastically placed by damper-spring systems and moves in both the in-line and cross-flow directions. In such models, each circular cylinder is assumed as a rigid body. On the other hand, we do not introduce a turbulent model such as the Large Eddy Simulation (LES) or Reynolds Averaged Navier-Stokes (RANS) models into the numerical scheme to compute the fluid flow. Our numerical procedure to capture the flow-induced vibration phenomena of the upstream circular cylinder is treated as a fluid-structure interaction problem in which the ideas of weak coupling is taken into consideration.
Three Dimensional Dirac Semimetals
NASA Astrophysics Data System (ADS)
Zaheer, Saad
2014-03-01
Dirac points on the Fermi surface of two dimensional graphene are responsible for its unique electronic behavior. One can ask whether any three dimensional materials support similar pseudorelativistic physics in their bulk electronic spectra. This possibility has been investigated theoretically and is now supported by two successful experimental demonstrations reported during the last year. In this talk, I will summarize the various ways in which Dirac semimetals can be realized in three dimensions with primary focus on a specific theory developed on the basis of representations of crystal spacegroups. A three dimensional Dirac (Weyl) semimetal can appear in the presence (absence) of inversion symmetry by tuning parameters to the phase boundary separating a bulk insulating and a topological insulating phase. More generally, we find that specific rules governing crystal symmetry representations of electrons with spin lead to robust Dirac points at high symmetry points in the Brillouin zone. Combining these rules with microscopic considerations identifies six candidate Dirac semimetals. Another method towards engineering Dirac semimetals involves combining crystal symmetry and band inversion. Several candidate materials have been proposed utilizing this mechanism and one of the candidates has been successfully demonstrated as a Dirac semimetal in two independent experiments. Work carried out in collaboration with: Julia A. Steinberg, Steve M. Young, J.C.Y. Teo, C.L. Kane, E.J. Mele and Andrew M. Rappe.
NASA Astrophysics Data System (ADS)
Cilona, A.; Arzilli, F.; Mancini, L.; Emanuele, T.
2014-12-01
Porous carbonates form important reservoirs for water and hydrocarbons. The fluid flow properties of carbonate reservoirs may be affected by post-depositional processes (e.g., mechanical and chemical), which need to be quantified. Field-based studies described bed-parallel compaction bands (CBs) within carbonates with a wide range of porosities. These burial-related structures accommodate volumetric strain by grain rotation, translation, pore collapse and pressure solution. Recently, the same structures have been reproduced for the first time in the laboratory by performing triaxial compaction experiments on porous grainstones. These laboratory studies characterized and compared the microstructures of natural and laboratory CBs, but no analysis of pore connectivity has been performed. In this paper, we use an innovative approach to characterize the pore networks (e.g. porosity, connectivity) of natural and laboratory CBs and compare them with the host rock one. We collected the data using the synchrotron X-ray computed microtomography technique at the SYRMEP beamline of the Elettra-Sincrotrone Trieste Laboratory (Italy). Quantitative analyses of the samples were performed with the Pore3D software library. The porosity was calculated from segmented 3D images of pristine and deformed carbonates. A process of skeletonization was then applied to quantify the number of connected pores within the rock volume. The analysis of the skeleton allowed us to highlight the differences between natural and laboratory CBs, and to investigate how pore connectivity evolves as a function of different deformation pathways. Both pore volume and connectivity are reduced within the CBs respect to the pristine rock and the natural CB has a lower porosity with respect to the laboratory one. The grain contacts in the natural CB are welded, whereas in the laboratory one they have more irregular shapes and grain crushing is the predominant process.
Three-dimensional Camera Phone
NASA Astrophysics Data System (ADS)
Iizuka, Keigo
2004-12-01
An inexpensive technique for realizing a three-dimensional (3D) camera phone display is presented. Light from the liquid-crystal screen of a camera phone is linearly polarized, and its direction of polarization is easily manipulated by a cellophane sheet used as a half-waveplate. The novel 3D camera phone display is made possible solely by optical components without resorting to computation, so that the 3D image is displayed in real time. Quality of the original image is not sacrificed in the process of converting it into a 3D image.
Worm, Esben S.; Hoyer, Morten; Fledelius, Walther; Nielsen, Jens E.; Larsen, Lars P.; Poulsen, Per R.
2012-05-01
Purpose: To develop and evaluate accurate and objective on-line patient setup based on a novel semiautomatic technique in which three-dimensional marker trajectories were estimated from two-dimensional cone-beam computed tomography (CBCT) projections. Methods and Materials: Seven treatment courses of stereotactic body radiotherapy for liver tumors were delivered in 21 fractions in total to 6 patients by a linear accelerator. Each patient had two to three gold markers implanted close to the tumors. Before treatment, a CBCT scan with approximately 675 two-dimensional projections was acquired during a full gantry rotation. The marker positions were segmented in each projection. From this, the three-dimensional marker trajectories were estimated using a probability based method. The required couch shifts for patient setup were calculated from the mean marker positions along the trajectories. A motion phantom moving with known tumor trajectories was used to examine the accuracy of the method. Trajectory-based setup was retrospectively used off-line for the first five treatment courses (15 fractions) and on-line for the last two treatment courses (6 fractions). Automatic marker segmentation was compared with manual segmentation. The trajectory-based setup was compared with setup based on conventional CBCT guidance on the markers (first 15 fractions). Results: Phantom measurements showed that trajectory-based estimation of the mean marker position was accurate within 0.3 mm. The on-line trajectory-based patient setup was performed within approximately 5 minutes. The automatic marker segmentation agreed with manual segmentation within 0.36 {+-} 0.50 pixels (mean {+-} SD; pixel size, 0.26 mm in isocenter). The accuracy of conventional volumetric CBCT guidance was compromised by motion smearing ({<=}21 mm) that induced an absolute three-dimensional setup error of 1.6 {+-} 0.9 mm (maximum, 3.2) relative to trajectory-based setup. Conclusions: The first on-line clinical use of
Hou, Baolin; Han, Hongjun; Zhuang, Haifeng; Xu, Peng; Jia, Shengyong; Li, Kun
2015-11-01
A novel integrated process with three-dimensional electro-Fenton (3D EF) and biological activated carbon (BAC) was employed in advanced treatment of biologically pretreated Lurgi coal gasification wastewater. SAC-Fe (sludge deserved activated carbon from sewage and iron sludge) and SAC (sludge deserved activated carbon) were used in 3D EF as catalytic particle electrodes (CPEs) and in BAC as carriers respectively. Results indicated that 3D EF with SAC-Fe as CPEs represented excellent pollutants and COLOR removals as well as biodegradability improvement. The efficiency enhancement attributed to generating more H2O2 and OH. The integrated process exhibited efficient performance of COD, BOD5, total phenols, TOC, TN and COLOR removals at a much shorter retention time, with the corresponding concentrations in effluent of 31.18, 6.69, 4.29, 17.82, 13.88mg/L and <20 times, allowing discharge criteria to be met. The integrated system was efficient, cost-effective and ecological sustainable and could be a promising technology for engineering applications. PMID:26227570
Three dimensional interactive display
NASA Technical Reports Server (NTRS)
Vranish, John M. (Inventor)
2005-01-01
A three-dimensional (3-D) interactive display and method of forming the same, includes a transparent capaciflector (TC) camera formed on a transparent shield layer on the screen surface. A first dielectric layer is formed on the shield layer. A first wire layer is formed on the first dielectric layer. A second dielectric layer is formed on the first wire layer. A second wire layer is formed on the second dielectric layer. Wires on the first wire layer and second wire layer are grouped into groups of parallel wires with a turnaround at one end of each group and a sensor pad at the opposite end. An operational amplifier is connected to each of the sensor pads and the shield pad biases the pads and receives a signal from connected sensor pads in response to intrusion of a probe. The signal is proportional to probe location with respect to the monitor screen.
Eren, Ezgi Can; Dixit, Ram; Gautam, Natarajan
2010-08-01
The noncentrosomal cortical microtubules (CMTs) of plant cells self-organize into a parallel three-dimensional (3D) array that is oriented transverse to the cell elongation axis in wild-type plants and is oblique in some of the mutants that show twisted growth. To study the mechanisms of CMT array organization, we developed a 3D computer simulation model based on experimentally observed properties of CMTs. Our computer model accurately mimics transverse array organization and other fundamental properties of CMTs observed in rapidly elongating wild-type cells as well as the defective CMT phenotypes observed in the Arabidopsis mor1-1 and fra2 mutants. We found that CMT interactions, boundary conditions, and the bundling cutoff angle impact the rate and extent of CMT organization, whereas branch-form CMT nucleation did not significantly impact the rate of CMT organization but was necessary to generate polarity during CMT organization. We also found that the dynamic instability parameters from twisted growth mutants were not sufficient to generate oblique CMT arrays. Instead, we found that parameters regulating branch-form CMT nucleation and boundary conditions at the end walls are important for forming oblique CMT arrays. Together, our computer model provides new mechanistic insights into how plant CMTs self-organize into specific 3D arrangements. PMID:20519434
Eren, Ezgi Can; Gautam, Natarajan
2010-01-01
The noncentrosomal cortical microtubules (CMTs) of plant cells self-organize into a parallel three-dimensional (3D) array that is oriented transverse to the cell elongation axis in wild-type plants and is oblique in some of the mutants that show twisted growth. To study the mechanisms of CMT array organization, we developed a 3D computer simulation model based on experimentally observed properties of CMTs. Our computer model accurately mimics transverse array organization and other fundamental properties of CMTs observed in rapidly elongating wild-type cells as well as the defective CMT phenotypes observed in the Arabidopsis mor1-1 and fra2 mutants. We found that CMT interactions, boundary conditions, and the bundling cutoff angle impact the rate and extent of CMT organization, whereas branch-form CMT nucleation did not significantly impact the rate of CMT organization but was necessary to generate polarity during CMT organization. We also found that the dynamic instability parameters from twisted growth mutants were not sufficient to generate oblique CMT arrays. Instead, we found that parameters regulating branch-form CMT nucleation and boundary conditions at the end walls are important for forming oblique CMT arrays. Together, our computer model provides new mechanistic insights into how plant CMTs self-organize into specific 3D arrangements. PMID:20519434
Multiscale modeling of three-dimensional genome
NASA Astrophysics Data System (ADS)
Zhang, Bin; Wolynes, Peter
The genome, the blueprint of life, contains nearly all the information needed to build and maintain an entire organism. A comprehensive understanding of the genome is of paramount interest to human health and will advance progress in many areas, including life sciences, medicine, and biotechnology. The overarching goal of my research is to understand the structure-dynamics-function relationships of the human genome. In this talk, I will be presenting our efforts in moving towards that goal, with a particular emphasis on studying the three-dimensional organization, the structure of the genome with multi-scale approaches. Specifically, I will discuss the reconstruction of genome structures at both interphase and metaphase by making use of data from chromosome conformation capture experiments. Computationally modeling of chromatin fiber at atomistic level from first principles will also be presented as our effort for studying the genome structure from bottom up.
Three-dimensional printing physiology laboratory technology.
Sulkin, Matthew S; Widder, Emily; Shao, Connie; Holzem, Katherine M; Gloschat, Christopher; Gutbrod, Sarah R; Efimov, Igor R
2013-12-01
Since its inception in 19th-century Germany, the physiology laboratory has been a complex and expensive research enterprise involving experts in various fields of science and engineering. Physiology research has been critically dependent on cutting-edge technological support of mechanical, electrical, optical, and more recently computer engineers. Evolution of modern experimental equipment is constrained by lack of direct communication between the physiological community and industry producing this equipment. Fortunately, recent advances in open source technologies, including three-dimensional printing, open source hardware and software, present an exciting opportunity to bring the design and development of research instrumentation to the end user, i.e., life scientists. Here we provide an overview on how to develop customized, cost-effective experimental equipment for physiology laboratories. PMID:24043254
NASA Technical Reports Server (NTRS)
Degani, A. T.; Walker, J. D. A.
1990-01-01
In the calculation of turbulent boundary layers, a large number of mesh points are required to adequately resolve the intense variation in the velocity and enthalpy in the near-wall region. A substantial reduction in computational effort may be realized by representing the velocity and enthalpy profiles in the wall layer by analytical embedded functions. The effectively inviscid flow in the outer part of the boundary layer may then be resolved by employing a relatively coarser mesh. To obtain complete profiles, the outer numerical solution is matched asymptotically to the inner wall-layer analytical solution. To date, this approach has been restricted to two-dimensional flows; in the present study, a method which may be utilized for turbulent boundary layers with heat transfer in a plane of symmetry is developed as a first step in the application of the embedded-function method to full three-dimensional flows. The present method uses only about half as many mesh points as that required in a conventional procedure, which calculates the flow all the way to the wall, but there is no degradation in accuracy of the computed results.
NASA Astrophysics Data System (ADS)
Ball, W. H.; Beeck, B.; Cameron, R. H.; Gizon, L.
2016-08-01
Context. Space-based observations of solar-like oscillators have identified large numbers of stars in which many individual mode frequencies can be precisely measured. However, current stellar models predict oscillation frequencies that are systematically affected by simplified modelling of the near-surface layers. Aims: We use three-dimensional radiation hydrodynamics simulations to better model the near-surface equilibrium structure of dwarfs with spectral types F3, G2, K0 and K5, and examine the differences between oscillation mode frequencies computed in stellar models with and without the improved near-surface equilibrium structure. Methods: We precisely match stellar models to the simulations' gravities and effective temperatures at the surface, and to the temporally- and horizontally-averaged densities and pressures at their deepest points. We then replace the near-surface structure with that of the averaged simulation and compute the change in the oscillation mode frequencies. We also fit the differences using several parametric models currently available in the literature. Results: The surface effect in the stars of solar-type and later is qualitatively similar and changes steadily with decreasing effective temperature. In particular, the point of greatest frequency difference decreases slightly as a fraction of the acoustic cut-off frequency and the overall scale of the surface effect decreases. The surface effect in the hot, F3-type star follows the same trend in scale (i.e. it is larger in magnitude) but shows a different overall variation with mode frequency. We find that a two-term fit using the cube and inverse of the frequency divided by the mode inertia is best able to reproduce the surface terms across all four spectral types, although the scaled solar term and a modified Lorentzian function also match the three cooler simulations reasonably well. Conclusions: Three-dimensional radiation hydrodynamics simulations of near-surface convection can be
NASA Astrophysics Data System (ADS)
Rolland, Joran; Domeisen, Daniela I. V.
2016-04-01
Many geophysical waves in the atmosphere or in the ocean have a three dimensional structure and contain a range of scales. This is for instance the case of planetary waves in the stratosphere connected to baroclinic eddies in the troposphere [1]. In the study of such waves from reanalysis data or output of numerical simulations, Empirical Orthogonal Functions (EOF) obtained as a Proper Orthogonal Decomposition of the data sets have been of great help. However, most of these computations rely on the diagonalisation of space correlation matrices: this means that the considered data set can only have a limited number of gridpoints. The main consequence is that such analyses are often only performed in planes (as function of height and latitude, or longitude and latitude for instance), which makes the educing of the three dimensional structure of the wave quite difficult. In the case of the afore mentionned waves, the matter of the longitudinal dependence or the proper correlation between modes through the tropopause is an open question. An elegant manner to circumvent this problem is to consider the output of the Orthogonal Decomposition as a whole. Indeed, it has been shown that the normalised time series of the amplitude of each EOF, far from just being decorrelated from one another, are actually another set of orthogonal functions. These can actually be computed through the diagonlisation of the time correlation matrix of the data set, just like the EOF were the result of the diagonalisation of the space correlation matrix. The signal is then fully decomposed in the framework of the Bi-Orthogonal Decomposition as the sum of the nth explained variance, time the nth eigenmode of the time correlation times the nth eigenmode of the spacial correlations [2,3]. A practical consequence of this result is that the EOF can be reconstructed from the projection of the dataset onto the eigenmodes of the time correlation matrix in the so-called snapshot method [4]. This is very
NASA Astrophysics Data System (ADS)
Rolland, Joran; Domeisen, Daniela I. V.
2016-04-01
Many geophysical waves in the atmosphere or in the ocean have a three dimensional structure and contain a range of scales. This is for instance the case of planetary waves in the stratosphere connected to baroclinic eddies in the troposphere [1]. In the study of such waves from reanalysis data or output of numerical simulations, Empirical Orthogonal Functions (EOF) obtained as a Proper Orthogonal Decomposition of the data sets have been of great help. However, most of these computations rely on the diagonalisation of space correlation matrices: this means that the considered data set can only have a limited number of gridpoints. The main consequence is that such analyses are often only performed in planes (as function of height and latitude, or longitude and latitude for instance), which makes the educing of the three dimensional structure of the wave quite difficult. In the case of the afore mentionned waves, the matter of the longitudinal dependence or the proper correlation between modes through the tropopause is an open question. An elegant manner to circumvent this problem is to consider the output of the Orthogonal Decomposition as a whole. Indeed, it has been shown that the normalised time series of the amplitude of each EOF, far from just being decorrelated from one another, are actually another set of orthogonal functions. These can actually be computed through the diagonlisation of the time correlation matrix of the data set, just like the EOF were the result of the diagonalisation of the space correlation matrix. The signal is then fully decomposed in the framework of the Bi-Orthogonal Decomposition as the sum of the nth explained variance, time the nth eigenmode of the time correlation times the nth eigenmode of the spacial correlations [2,3]. A practical consequence of this result is that the EOF can be reconstructed from the projection of the dataset onto the eigenmodes of the time correlation matrix in the so-called snapshot method [4]. This is very
Rohatgi, U.S.; Cheng, H.S.; Khan, H.J.; Mallen, A.N.; Neymotin, L.Y.
1998-03-01
This document describes the major modifications and improvements made to the modeling of the RAMONA-3B/MOD0 code since 1981, when the code description and assessment report was completed. The new version of the code is RAMONA-4B. RAMONA-4B is a systems transient code for application to different versions of Boiling Water Reactors (BWR) such as the current BWR, the Advanced Boiling Water Reactor (ABWR), and the Simplified Boiling Water Reactor (SBWR). This code uses a three-dimensional neutron kinetics model coupled with a multichannel, non-equilibrium, drift-flux, two-phase flow formulation of the thermal hydraulics of the reactor vessel. The code is designed to analyze a wide spectrum of BWR core and system transients and instability issues. Chapter 1 is an overview of the code`s capabilities and limitations; Chapter 2 discusses the neutron kinetics modeling and the implementation of reactivity edits. Chapter 3 is an overview of the heat conduction calculations. Chapter 4 presents modifications to the thermal-hydraulics model of the vessel, recirculation loop, steam separators, boron transport, and SBWR specific components. Chapter 5 describes modeling of the plant control and safety systems. Chapter 6 presents and modeling of Balance of Plant (BOP). Chapter 7 describes the mechanistic containment model in the code. The content of this report is complementary to the RAMONA-3B code description and assessment document. 53 refs., 81 figs., 13 tabs.
NASA Astrophysics Data System (ADS)
Takenaka, H.; Komatsu, M.; Toyokuni, G.; Nakamura, T.; Okamoto, T.
2015-12-01
A simple and efficient finite-difference scheme is developed to compute seismic wave propagation for a partial spherical shell model of a three-dimensionally (3-D) heterogeneous global earth structure. This new scheme solves the elastodynamic equations in the "quasi-Cartesian" coordinate system similar to a local Cartesian one, instead of the spherical coordinate system, with a staggered-grid finite-difference method in time domain (FDTD) which is one of the most popular numerical methods in seismic motion simulations for local to regional scale models. The proposed scheme may be useful for modeling seismic wave propagation in a very large region of sub-global scale beyond regional and less than global ones, where the effects of roundness of earth cannot be ignored. In "quasi-Cartesian" coordinates, x, y, and z are set to be locally in directions of latitude, longitude and depth, respectively. The stencil for each of the x-derivatives then depends on the depth coordinate at the evaluation point, while the stencil for each of the y-derivatives varies with both coordinates of the depth and latitude. In order to reduce lateral variations of the horizontal finite-difference stencils over the computational domain, we move the target area to a location around the equator of the computational spherical coordinate system using a way similar to the conversion from equatorial coordinates to ecliptic coordinates. The developed scheme can be easily implemented in 3-D Cartesian FDTD codes for local to regional scale modeling by changing a very small part of the codes. Our scheme may be able to open a window for multi-scale modeling of seismic wave propagation in scales from sub-global to local one.
Shakhawath Hossain, Md; Bergstrom, D J; Chen, X B
2015-12-01
The in vitro chondrocyte cell culture for cartilage tissue regeneration in a perfusion bioreactor is a complex process. Mathematical modeling and computational simulation can provide important insights into the culture process, which would be helpful for selecting culture conditions to improve the quality of the developed tissue constructs. However, simulation of the cell culture process is a challenging task due to the complicated interaction between the cells and local fluid flow and nutrient transport inside the complex porous scaffolds. In this study, a mathematical model and computational framework has been developed to simulate the three-dimensional (3D) cell growth in a porous scaffold placed inside a bi-directional flow perfusion bioreactor. The model was developed by taking into account the two-way coupling between the cell growth and local flow field and associated glucose concentration, and then used to perform a resolved-scale simulation based on the lattice Boltzmann method (LBM). The simulation predicts the local shear stress, glucose concentration, and 3D cell growth inside the porous scaffold for a period of 30 days of cell culture. The predicted cell growth rate was in good overall agreement with the experimental results available in the literature. This study demonstrates that the bi-directional flow perfusion culture system can enhance the homogeneity of the cell growth inside the scaffold. The model and computational framework developed is capable of providing significant insight into the culture process, thus providing a powerful tool for the design and optimization of the cell culture process. PMID:26061385
Tsukada, Sachiyuki; Wakui, Motohiro; Yoshizawa, Hiroshi; Miyao, Masunao; Honma, Takeshi
2016-01-01
Background: Fixed angle sliding hip screw devices allow controlled impaction between the head neck fragment and the femoral shaft fragment in the surgical treatment of pertrochanteric fractures. This study was performed to evaluate the frequency and pattern of comminution at the fracture site, which may prevent the intended impaction. Materials and Methods: Three-dimensional computed tomography was used to investigate 101 pertrochanteric fractures treated with fixed angle sliding hip screw devices, with emphasis on the comminuted cortex. A comminuted fracture was defined as a fracture that had a third fracture fragment at the main fracture line. Results: There were 40 fractures without comminution and 61 with comminution. All 61 comminuted fractures had a comminuted posterior cortex, and 3 of 61 fractures also had comminution at the anterior cortex. The prevalence of cutting out of the implant from the femoral head was significantly higher in cases involving comminution at both the posterior and anterior cortices than in cases involving comminution only at the posterior cortex (66.7 % and 3.4 %, p < 0.0001). Conclusion: The posterior cortex was comminuted in 60.4% of pertrochanteric fractures and the anterior cortex in 3.0%. Intended impaction at the fracture site could not be obtained at any cortex in cases with comminution at both the anterior and posterior cortices; comminution at the anterior cortex may be a predictor of cutting out. PMID:27347234
Kang, S-H; Lee, J-W; Lim, S-H; Kim, Y-H; Kim, M-K
2014-10-01
The goal of the present study was to compare the accuracy of dental image replacement on a cone beam computed tomography (CBCT) image using digital image data from three-dimensional (3D) optical scanning of a dental cast, occlusal bite, and bite tray impression. A Bracket Typodont dental model was used. CBCT of the dental model was performed and the data were converted to stereolithography (STL) format. Three experimental materials, a dental cast, occlusal bite, and bite tray impression, were optically scanned in 3D. STL files converted from the CBCT of the Typodont model and the 3D optical-scanned STL files of the study materials were image-registered. The error range of each methodology was measured and compared with a 3D optical scan of the Typodont. For the three materials, the smallest error observed was 0.099±0.114mm (mean error±standard deviation) for registering the 3D optical scan image of the dental cast onto the CBCT dental image. Although producing a dental cast can be laborious, the study results indicate that it is the preferred method. In addition, an occlusal bite is recommended when bite impression materials are used. PMID:25015906
Thimm, Benjamin W; Hofmann, Sandra; Schneider, Philipp; Carretta, Roberto; Müller, Ralph
2012-03-01
Computed tomography (CT) represents a truly three-dimensional (3D) imaging technique that can provide high-resolution images on the cellular level. Thus, one approach to detect single cells is X-ray absorption-based CT, where cells are labeled with a dense, opaque material providing the required contrast for CT imaging. Within the present work, a novel cell-labeling method has been developed showing the feasibility of labeling fixed cells with iron oxide (FeO) particles for subsequent CT imaging and quantitative morphometry. A biotin-streptavidin detection system was exploited to bind FeO particles to its target endothelial cells. The binding of the particles was predominantly close to the cell centers on 2D surfaces as shown by light microscopy, scanning electron microscopy, and CT. When cells were cultured on porous, 3D polyurethane surfaces, significantly more FeO particles were detected compared with surfaces without cells and FeO particle labeling using CT. Here, we report on the implementation and evaluation of a novel cell detection method based on high-resolution CT. This system has potential in cell tracking for 3D in vitro imaging in the future. PMID:21951168
Hegde, Mithra N; Tahiliani, Divya; Shetty, Heeresh; Bhat, Ganesh T; Shetty, Shishir
2014-01-01
Background: Conventional radiographic techniques being two dimensional, has its restrictions and is confined to limited diagnostic value. However, the incorporation of Cone Beam Computed Tomography (CBCT) gives a three dimensional insight to the tooth morphology and leads to better evaluation and treatment management. Aim: The aim of this study was to evaluate and assess the root canal morphology of mandibular pre-molars in South Indian Population using CBCT radiographic technique. Materials and Methods: One thousand and eighty six and 814 fully erupted mandibular first and second premolars respectively were scanned using CBCT to evaluate the canal morphology according to Vertucci and Gulabiwala’s classification. Results: The most common configuration in mandibular first and second premolars was Vertucci’s Type I(83.81% and 93.48% respectively) followed by Type V (11.97% and 3.5% respectively). Conclusion: South Indian population presented Type IV ertucci’s canal morphology as the most common in mandibular first and second pre-molars followed by Type V. CBCT scanning poses a greater advantage in assessing the complexity of root canal morphology and planning an appropriate endodontic treatment for the same. PMID:25302261
Xuan, Ruijiao; Zhao, Xinyan; Hu, Doudou; Jian, Jianbo; Wang, Tailing; Hu, Chunhong
2015-01-01
X-ray phase-contrast imaging (PCI) can substantially enhance contrast, and is particularly useful in differentiating biological soft tissues with small density differences. Combined with computed tomography (CT), PCI-CT enables the acquisition of accurate microstructures inside biological samples. In this study, liver microvasculature was visualized without contrast agents in vitro with PCI-CT using liver fibrosis samples induced by bile duct ligation (BDL) in rats. The histological section examination confirmed the correspondence of CT images with the microvascular morphology of the samples. By means of the PCI-CT and three-dimensional (3D) visualization technique, 3D microvascular structures in samples from different stages of liver fibrosis were clearly revealed. Different types of blood vessels, including portal veins and hepatic veins, in addition to ductular proliferation and bile ducts, could be distinguished with good sensitivity, excellent specificity and excellent accuracy. The study showed that PCI-CT could assess the morphological changes in liver microvasculature that result from fibrosis and allow characterization of the anatomical and pathological features of the microvasculature. With further development of PCI-CT technique, it may become a novel noninvasive imaging technique for the auxiliary analysis of liver fibrosis. PMID:26212186
Kim, Min Sun; Lee, Eun Joo; Song, In Ja; Lee, Jae-Seo; Kang, Byung-Cheol
2015-01-01
Purpose The purpose of this study was to evaluate the influence of methods of establishing the midsagittal reference plane (MRP) on the locations of midfacial landmarks in the three-dimensional computed tomography (CT) analysis of facial asymmetry. Materials and Methods A total of 24 patients (12 male and 12 female; mean age, 22.5 years; age range, 18.2-29.7 years) with facial asymmetry were included in this study. The MRP was established using two different methods on each patient's CT image. The x-coordinates of four midfacial landmarks (the menton, nasion, upper incisor, and lower incisor) were obtained by measuring the distance and direction of the landmarks from the MRP, and the two methods were compared statistically. The direction of deviation and the severity of asymmetry found using each method were also compared. Results The x-coordinates of the four anatomic landmarks all showed a statistically significant difference between the two methods of establishing the MRP. For the nasion and lower incisor, six patients (25.0%) showed a change in the direction of deviation. The severity of asymmetry also changed in 16 patients (66.7%). Conclusion The results of this study suggest that the locations of midfacial landmarks change significantly according to the method used to establish the MRP. PMID:26730370
Lee, Hyeong-Geun
2015-01-01
Objectives The purpose of this study was to estimate the volumetric change of augmented autobone harvested from mandibular body cortical bone, using cone-beam computed tomography (CBCT) and three-dimensional reconstruction. In addition, the clinical success of dental implants placed 4 to 6 months after bone grafting was also evaluated. Materials and Methods Ninety-five patients (48 men and 47 women) aged 19 to 72 years were included in this study. A total of 128 graft sites were evaluated. The graft sites were divided into three parts: anterior and both posterior regions of one jaw. All patients included in the study were scheduled for an onlay graft and implantation using a two-stage procedure. The dental implants were inserted 4 to 6 months after the bone graft. Volumetric stability was evaluated by serial CBCT images. Results No major complications were observed for the donor sites. A total of 128 block bones were used to augment severely resorbed alveolar bone. Only 1 of the 128 bone grafts was resorbed by more than half, and that was due to infection. In total, the average amount of residual grafted bone after resorption at the recipient sites was 74.6%±8.4%. Conclusion Volumetric stability of mandibular body autogenous block grafts is predictable. The procedure is satisfactory for patients who want dental implants regardless of atrophic alveolar bone. PMID:26568924
Dhingra, Annil; Dayal, Charu; Singh, Amteshwar; Bhardwaj, Neetika
2015-01-01
Introduction: Obtaining a correct working length is critical to the success of endodontic therapy. The aim of this clinical study was to compare the effect of working length determination using radiovisiography (RVG) and two-dimensional (2D) and three-dimensional (3D) measurements using cone-beam computed tomography (CBCT). Materials and Methods: Thirty mandibular teeth were taken and three groups of 10 each were made. Teeth with previous endodontic treatments, metal restorations, resorptions, incomplete apex formations, and multiple visible foramina were excluded. The root canal length was determined using RVG, CBCT measurement method 2D, and CBCT measurement method 3D. The difference between CBCT measurements, RVG, and the actual canal length were compared to evaluate the accuracy of each method. Results: No significant statistically difference was seen with 3D measurements and actual measurements. Measurements with RVG were better than CBCT 2D. Conclusion: Under experimental conditions, CBCT 3D measurements are accurate than RVG and CBCT 2D in the determination of root canal length. PMID:26752880
Zhang, Yang; Toksöz, M Nafi
2012-08-01
The seismic response of saturated porous rocks is studied numerically using microtomographic images of three-dimensional digitized Berea sandstones. A stress-strain calculation is employed to compute the velocities and attenuations of rock samples whose sizes are much smaller than the seismic wavelength of interest. To compensate for the contributions of small cracks lost in the imaging process to the total velocity and attenuation, a hybrid method is developed to recover the crack distribution, in which the differential effective medium theory, the Kuster-Toksöz model, and a modified squirt-flow model are utilized in a two-step Monte Carlo inversion. In the inversion, the velocities of P- and S-waves measured for the dry and water-saturated cases, and the measured attenuation of P-waves for different fluids are used. By using such a hybrid method, both the velocities of saturated porous rocks and the attenuations are predicted accurately when compared to laboratory data. The hybrid method is a practical way to model numerically the seismic properties of saturated porous rocks until very high resolution digital data are available. Cracks lost in the imaging process are critical for accurately predicting velocities and attenuations of saturated porous rocks. PMID:22894185
NASA Astrophysics Data System (ADS)
Xuan, Ruijiao; Zhao, Xinyan; Hu, Doudou; Jian, Jianbo; Wang, Tailing; Hu, Chunhong
2015-07-01
X-ray phase-contrast imaging (PCI) can substantially enhance contrast, and is particularly useful in differentiating biological soft tissues with small density differences. Combined with computed tomography (CT), PCI-CT enables the acquisition of accurate microstructures inside biological samples. In this study, liver microvasculature was visualized without contrast agents in vitro with PCI-CT using liver fibrosis samples induced by bile duct ligation (BDL) in rats. The histological section examination confirmed the correspondence of CT images with the microvascular morphology of the samples. By means of the PCI-CT and three-dimensional (3D) visualization technique, 3D microvascular structures in samples from different stages of liver fibrosis were clearly revealed. Different types of blood vessels, including portal veins and hepatic veins, in addition to ductular proliferation and bile ducts, could be distinguished with good sensitivity, excellent specificity and excellent accuracy. The study showed that PCI-CT could assess the morphological changes in liver microvasculature that result from fibrosis and allow characterization of the anatomical and pathological features of the microvasculature. With further development of PCI-CT technique, it may become a novel noninvasive imaging technique for the auxiliary analysis of liver fibrosis.
Rohatgi, U.S.; Cheng, H.S.; Khan, H.J.; Mallen, A.N.; Neymotin, L.Y.
1998-03-01
This document is the User`s Manual for the Boiling Water Reactor (BWR), and Simplified Boiling Water Reactor (SBWR) systems transient code RAMONA-4B. The code uses a three-dimensional neutron-kinetics model coupled with a multichannel, nonequilibrium, drift-flux, phase-flow model of the thermal hydraulics of the reactor vessel. The code is designed to analyze a wide spectrum of BWR core and system transients. Chapter 1 gives an overview of the code`s capabilities and limitations; Chapter 2 describes the code`s structure, lists major subroutines, and discusses the computer requirements. Chapter 3 is on code, auxillary codes, and instructions for running RAMONA-4B on Sun SPARC and IBM Workstations. Chapter 4 contains component descriptions and detailed card-by-card input instructions. Chapter 5 provides samples of the tabulated output for the steady-state and transient calculations and discusses the plotting procedures for the steady-state and transient calculations. Three appendices contain important user and programmer information: lists of plot variables (Appendix A) listings of input deck for sample problem (Appendix B), and a description of the plotting program PAD (Appendix C). 24 refs., 18 figs., 11 tabs.
NASA Astrophysics Data System (ADS)
Grah, Aleksander; Dreyer, Michael E.
2010-01-01
Spacecraft technology provides a series of applications for capillary channel flow. It can serve as a reliable means for positioning and transport of liquids under low gravity conditions. Basically, capillary channels provide liquid paths with one or more free surfaces. A problem may be flow instabilities leading to a collapse of the liquid surfaces. A result is undesired gas ingestion and a two phase flow which can in consequence cause several technical problems. The presented capillary channel consists of parallel plates with two free liquid surfaces. The flow rate is established by a pump at the channel outlet, creating a lower pressure within the channel. Owing to the pressure difference between the liquid phase and the ambient gas phase the free surfaces bend inwards and remain stable as long as they are able to resist the steady and unsteady pressure effects. For the numerical prediction of the flow stability two very different models are used. The one-dimensional unsteady model is mainly based on the Bernoulli equation, the continuity equation, and the Gauss-Laplace equation. For three-dimensional evaluations an open source computational fluid dynamics (CFD) tool is applied. For verifications the numerical results are compared with quasisteady and unsteady data of a sounding rocket experiment. Contrary to previous experiments this one results in a significantly longer observation sequence. Furthermore, the critical point of the steady flow instability could be approached by a quasisteady technique. As in previous experiments the comparison to the numerical model evaluation shows a very good agreement for the movement of the liquid surfaces and for the predicted flow instability. The theoretical prediction of the flow instability is related to the speed index, based on characteristic velocities of the capillary channel flow. Stable flow regimes are defined by stability criteria for steady and unsteady flow. The one-dimensional computation of the speed index
Three dimensional Dirac semimetals
NASA Astrophysics Data System (ADS)
Zaheer, Saad
We extend the physics of graphene to three dimensional systems by showing that Dirac points can exist on the Fermi surface of realistic materials in three dimensions. Many of the exotic electronic properties of graphene can be ascribed to the pseudorelativistic behavior of its charge carriers due to two dimensional Dirac points on the Fermi surface. We show that certain nonsymmorphic spacegroups exhibit Dirac points among the irreducible representations of the appropriate little group at high symmetry points on the surface of the Brillouin zone. We provide a list of all Brillouin zone momenta in the 230 spacegroups that can host Dirac points. We describe microscopic considerations necessary to design materials in one of the candidate spacegroups such that the Dirac point appears at the Fermi energy without any additional non-Dirac-like Fermi pockets. We use density functional theory based methods to propose six new Dirac semimetals: BiO 2 and SbO2 in the beta-cristobalite lattice (spacegroup 227), and BiCaSiO4, BiMgSiO4, BiAlInO 4, and BiZnSiO4 in the distorted spinels lattice (spacegroup 74). Additionally we derive effective Dirac Hamiltonians given group representative operators as well as tight binding models incorporating spin-orbit coupling. Finally we study the Fermi surface of zincblende (spacegroup 216) HgTe which is effectively point-like at Gamma in the Brillouin zone and exhibits accidental degeneracies along a threefold rotation axis. Whereas compressive strain gaps the band structure into a topological insulator, tensile strain shifts the accidental degeneracies away from Gamma and enlarges the Fermi surface. States on the Fermi surface exhibit nontrivial spin texture marked by winding of spins around the threefold rotation axis and by spin vortices indicating a change in the winding number. This is confirmed by microscopic calculations performed in tensile strained HgTe and Hg0.5Zn 0.5 Te as well as k.p theory. We conclude with a summary of recent
Ishihara, D; Horie, T; Niho, T
2014-01-01
The relative importance of the wing's inertial and aerodynamic forces is the key to revealing how the kinematical characteristics of the passive pitching motion of insect flapping wings are generated, which is still unclear irrespective of its importance in the design of insect-like micro air vehicles. Therefore, we investigate three species of flies in order to reveal this, using a novel fluid-structure interaction analysis that consists of a dynamically scaled experiment and a three-dimensional finite element analysis. In the experiment, the dynamic similarity between the lumped torsional flexibility model as a first approximation of the dipteran wing and the actual insect is measured by the Reynolds number Re, the Strouhal number St, the mass ratio M, and the Cauchy number Ch. In the computation, the three-dimension is important in order to simulate the stable leading edge vortex and lift force in the present Re regime over 254. The drawback of the present experiment is the difficulty in satisfying the condition of M due to the limitation of available solid materials. The novelty of the present analysis is to complement this drawback using the computation. We analyze the following two cases: (a) The equilibrium between the wing's elastic and fluid forces is dynamically similar to that of the actual insect, while the wing's inertial force can be ignored. (b) All forces are dynamically similar to those of the actual insect. From the comparison between the results of cases (a) and (b), we evaluate the contributions of the equilibrium between the aerodynamic and the wing's elastic forces and the wing's inertial force to the passive pitching motion as 80-90% and 10-20%, respectively. It follows from these results that the dipteran passive pitching motion will be based on the equilibrium between the wing's elastic and aerodynamic forces, while it will be enhanced by the wing's inertial force. PMID:25378268
Guo, Bing; Li, Jian-Bin; Wang, Wei; Xu, Min; Li, Yan-Kang; Liu, Tong-Hai
2016-01-01
Purpose To investigate the potential dosimetric benefits from four-dimensional computed tomography (4DCT) compared with three-dimensional computed tomography (3DCT) in radiotherapy treatment planning for external-beam partial breast irradiation (EB-PBI). Patients and methods 3DCT and 4DCT scan sets were acquired for 20 patients who underwent EB-PBI. The volume of the tumor bed (TB) was determined based on seroma or surgical clips on 3DCT images (defined as TB3D) and the end inhalation (EI) and end exhalation (EE) phases of 4DCT images (defined as TBEI and TBEE, respectively). The clinical target volume (CTV) consisted of the TB plus a 1.0 cm margin. The planning target volume (PTV) was the CTV plus 0.5 cm (defined as PTV3D, PTVEI, and PTVEE). For each patient, a conventional 3D conformal plan (3D-CRT) was generated (defined as EB-PBI3D, EB-PBIEI, and EB-PBIEE). Results The PTV3D, PTVEI, and PTVEE were similar (P=0.549), but the PTV coverage of EB-PBI3D was significantly less than that of EB-PBIEI or EB-PBIEE (P=0.001 and P=0.025, respectively). There were no significant differences in the homogeneity or conformity indexes between the three treatment plans (P=0.125 and P=0.536, respectively). The EB-PBI3D plan resulted in the largest organs at risk dose. Conclusion There was a significant benefit for patients when using 3D-CRT based on 4DCT for EB-PBI with regard to reducing nontarget organ exposure. Respiratory motion did not affect the dosimetric distribution during free breathing, but might result in poor dose coverage when the PTV is determined using 3DCT. PMID:27099517
Use of advanced computers for aerodynamic flow simulation
NASA Technical Reports Server (NTRS)
Bailey, F. R.; Ballhaus, W. F.
1980-01-01
The current and projected use of advanced computers for large-scale aerodynamic flow simulation applied to engineering design and research is discussed. The design use of mature codes run on conventional, serial computers is compared with the fluid research use of new codes run on parallel and vector computers. The role of flow simulations in design is illustrated by the application of a three dimensional, inviscid, transonic code to the Sabreliner 60 wing redesign. Research computations that include a more complete description of the fluid physics by use of Reynolds averaged Navier-Stokes and large-eddy simulation formulations are also presented. Results of studies for a numerical aerodynamic simulation facility are used to project the feasibility of design applications employing these more advanced three dimensional viscous flow simulations.
C Hann; M Bentley; A Vercnocke; E Ritman; M Fautsch
2011-12-31
The site of outflow resistance leading to elevated intraocular pressure in primary open-angle glaucoma is believed to be located in the region of Schlemm's canal inner wall endothelium, its basement membrane and the adjacent juxtacanalicular tissue. Evidence also suggests collector channels and intrascleral vessels may have a role in intraocular pressure in both normal and glaucoma eyes. Traditional imaging modalities limit the ability to view both proximal and distal portions of the trabecular outflow pathway as a single unit. In this study, we examined the effectiveness of three-dimensional micro-computed tomography (3D micro-CT) as a potential method to view the trabecular outflow pathway. Two normal human eyes were used: one immersion fixed in 4% paraformaldehyde and one with anterior chamber perfusion at 10 mmHg followed by perfusion fixation in 4% paraformaldehyde/2% glutaraldehyde. Both eyes were postfixed in 1% osmium tetroxide and scanned with 3D micro-CT at 2 {mu}m or 5 {mu}m voxel resolution. In the immersion fixed eye, 24 collector channels were identified with an average orifice size of 27.5 {+-} 5 {mu}m. In comparison, the perfusion fixed eye had 29 collector channels with a mean orifice size of 40.5 {+-} 13 {mu}m. Collector channels were not evenly dispersed around the circumference of the eye. There was no significant difference in the length of Schlemm's canal in the immersed versus the perfused eye (33.2 versus 35.1 mm). Structures, locations and size measurements identified by 3D micro-CT were confirmed by correlative light microscopy. These findings confirm 3D micro-CT can be used effectively for the non-invasive examination of the trabecular meshwork, Schlemm's canal, collector channels and intrascleral vasculature that comprise the distal outflow pathway. This imaging modality will be useful for non-invasive study of the role of the trabecular outflow pathway as a whole unit.
Buesch, D.C.; Nelson, J.E.; Dickerson, R.P.; Drake, R.M. II; San Juan, C.A.; Spengler, R.W.; Geslin, J.K.; Moyer, T.C.
1996-09-01
Yucca Mountain, Nevada is underlain by 14.0 to 11.6 Ma volcanic rocks tilted eastward 3{degree} to 20{degree} and cut by faults that were primarily active between 12.7 and 11.6 Ma. A three-dimensional computer-based model of the central block of the mountain consists of seven structural subblocks composed of six formations and the interstratified-bedded tuffaceous deposits. Rocks from the 12.7 Ma Tiva Canyon Tuff, which forms most of the exposed rocks on the mountain, to the 13.1 Ma Prow Pass Tuff are modeled with 13 surfaces. Modeled units represent single formations such as the Pah Canyon Tuff, grouped units such as the combination of the Yucca Mountain Tuff with the superjacent bedded tuff, and divisions of the Topopah Spring Tuff such as the crystal-poor vitrophyre interval. The model is based on data from 75 boreholes from which a structure contour map at the base of the Tiva Canyon Tuff and isochore maps for each unit are constructed to serve as primary input. Modeling consists of an iterative cycle that begins with the primary structure-contour map from which isochore values of the subjacent model unit are subtracted to produce the structure contour map on the base of the unit. This new structure contour map forms the input for another cycle of isochore subtraction to produce the next structure contour map. In this method of solids modeling, the model units are presented by surfaces (structure contour maps), and all surfaces are stored in the model. Surfaces can be converted to form volumes of model units with additional effort. This lithostratigraphic and structural model can be used for (1) storing data from, and planning future, site characterization activities, (2) preliminary geometry of units for design of Exploratory Studies Facility and potential repository, and (3) performance assessment evaluations.
Bamba, Yohei; Nonaka, Masahiro; Nakajima, Shin; Yamasaki, Mami
2011-01-01
Surgical procedures for spinal lipoma or tethered spinal cord after myelomeningocele (MMC) repair are often difficult and complicated, because the anatomical structures can be deformed in complex and unpredictable ways. Imaging helps the surgeon understand the patient's spinal anatomy. Whereas two-dimensional images provide only limited information for surgical planning, three-dimensional (3D) reconstructed computed tomography (CT)-magnetic resonance (MR) fusion images produce clearer representations of the spinal regions. Here we describe simple and quick methods for obtaining 3D reconstructed CT-MR fusion images for preoperative planning of surgical procedures using the iPlan(®) cranial (BrainLAB AG, Feldkirchen, Germany) neuronavigation software. 3D CT images of the vertebral bone were combined with heavily T(2)-weighted MR images of the spinal cord, lipoma, cerebrospinal fluid (CSF) space, and nerve root through a process of fusion, segmentation, and reconstruction of the 3D images. We also used our procedure called "Image Overlay" to directly project the 3D reconstructed image onto the body surface using an LED projector. The final reconstructed 3D images took 10-30 minutes to obtain, and provided the surgeon with a representation of the individual pathological structures, so enabled the design of effective surgical plans, even in patients with bony deformity such as scoliosis. None of the 19 patients treated based on our 3D reconstruction method has had neurological complications, except for CSF leakage. This 3D reconstructed imaging method, combined with Image Overlay, improves the visual understanding of complicated surgical situations, and should improve surgical efficiency and outcome. PMID:21613771
Suresh, Niraj; Stephens, Sean A; Adams, Lexor; Beck, Anthon N; McKinney, Adriana L; Varga, Tamas
2016-01-01
Plant roots play a critical role in plant-soil-microbe interactions that occur in the rhizosphere, as well as processes with important implications to climate change and crop management. Quantitative size information on roots in their native environment is invaluable for studying root growth and environmental processes involving plants. X-ray computed tomography (XCT) has been demonstrated to be an effective tool for in situ root scanning and analysis. We aimed to develop a costless and efficient tool that approximates the surface and volume of the root regardless of its shape from three-dimensional (3D) tomography data. The root structure of a Prairie dropseed (Sporobolus heterolepis) specimen was imaged using XCT. The root was reconstructed, and the primary root structure was extracted from the data using a combination of licensed and open-source software. An isosurface polygonal mesh was then created for ease of analysis. We have developed the standalone application imeshJ, generated in MATLAB(1), to calculate root volume and surface area from the mesh. The outputs of imeshJ are surface area (in mm(2)) and the volume (in mm(3)). The process, utilizing a unique combination of tools from imaging to quantitative root analysis, is described. A combination of XCT and open-source software proved to be a powerful combination to noninvasively image plant root samples, segment root data, and extract quantitative information from the 3D data. This methodology of processing 3D data should be applicable to other material/sample systems where there is connectivity between components of similar X-ray attenuation and difficulties arise with segmentation. PMID:27168248
Ren, Lei; Chetty, Indrin J.; Zhang Junan; Jin Jianyue; Wu, Q. Jackie; Yan Hui; Brizel, David M.; Lee, W. Robert; Movsas, Benjamin; Yin Fangfang
2012-04-01
Purpose: To develop a three-dimensional (3D) cone-beam computed tomography (CBCT) estimation method using a deformation field map, and to evaluate and optimize the efficiency and accuracy of the method for use in the clinical setting. Methods and Materials: We propose a method to estimate patient CBCT images using prior information and a deformation model. Patients' previous CBCT data are used as the prior information, and the new CBCT volume to be estimated is considered as a deformation of the prior image volume. The deformation field map is solved by minimizing deformation energy and maintaining new projection data fidelity using a nonlinear conjugate gradient method. This method was implemented in 3D form using hardware acceleration and multi-resolution scheme, and it was evaluated for different scan angles, projection numbers, and scan directions using liver, lung, and prostate cancer patient data. The accuracy of the estimation was evaluated by comparing the organ volume difference and the similarity between estimated CBCT and the CBCT reconstructed from fully sampled projections. Results: Results showed that scan direction and number of projections do not have significant effects on the CBCT estimation accuracy. The total scan angle is the dominant factor affecting the accuracy of the CBCT estimation algorithm. Larger scan angles yield better estimation accuracy than smaller scan angles. Lung cancer patient data showed that the estimation error of the 3D lung tumor volume was reduced from 13.3% to 4.3% when the scan angle was increased from 60 Degree-Sign to 360 Degree-Sign using 57 projections. Conclusions: The proposed estimation method is applicable for 3D DTS, 3D CBCT, four-dimensional CBCT, and four-dimensional DTS image estimation. This method has the potential for significantly reducing the imaging dose and improving the image quality by removing the organ distortion artifacts and streak artifacts shown in images reconstructed by the conventional
Brinkschulte, Markus; Bienert-Zeit, Astrid; Lüpke, Matthias; Hellige, Maren; Staszyk, Carsten; Ohnesorge, Bernhard
2013-01-01
The system of the paranasal sinuses morphologically represents one of the most complex parts of the equine body. A clear understanding of spatial relationships is needed for correct diagnosis and treatment. The purpose of this study was to describe the anatomy and volume of equine paranasal sinuses using three-dimensional (3D) reformatted renderings of computed tomography (CT) slices. Heads of 18 cadaver horses, aged 2-25 years, were analyzed by the use of separate semi-automated segmentation of the following bilateral paranasal sinus compartments: rostral maxillary sinus (Sinus maxillaris rostralis), ventral conchal sinus (Sinus conchae ventralis), caudal maxillary sinus (Sinus maxillaris caudalis), dorsal conchal sinus (Sinus conchae dorsalis), frontal sinus (Sinus frontalis), sphenopalatine sinus (Sinus sphenopalatinus), and middle conchal sinus (Sinus conchae mediae). Reconstructed structures were displayed separately, grouped, or altogether as transparent or solid elements to visualize individual paranasal sinus morphology. The paranasal sinuses appeared to be divided into two systems by the maxillary septum (Septum sinuum maxillarium). The first or rostral system included the rostral maxillary and ventral conchal sinus. The second or caudal system included the caudal maxillary, dorsal conchal, frontal, sphenopalatine, and middle conchal sinuses. These two systems overlapped and were interlocked due to the oblique orientation of the maxillary septum. Total volumes of the paranasal sinuses ranged from 911.50 to 1502.00 ml (mean ± SD, 1151.00 ± 186.30 ml). 3D renderings of equine paranasal sinuses by use of semi-automated segmentation of CT-datasets improved understanding of this anatomically challenging region. PMID:23890087
Interfaces for Advanced Computing.
ERIC Educational Resources Information Center
Foley, James D.
1987-01-01
Discusses the coming generation of supercomputers that will have the power to make elaborate "artificial realities" that facilitate user-computer communication. Illustrates these technological advancements with examples of the use of head-mounted monitors which are connected to position and orientation sensors, and gloves that track finger and…
NASA Technical Reports Server (NTRS)
Shih, T. I.-P.; Bailey, R. T.; Nguyen, H. L.; Roelke, R. J.
1990-01-01
An efficient computer program, called GRID2D/3D was developed to generate single and composite grid systems within geometrically complex two- and three-dimensional (2- and 3-D) spatial domains that can deform with time. GRID2D/3D generates single grid systems by using algebraic grid generation methods based on transfinite interpolation in which the distribution of grid points within the spatial domain is controlled by stretching functions. All single grid systems generated by GRID2D/3D can have grid lines that are continuous and differentiable everywhere up to the second-order. Also, grid lines can intersect boundaries of the spatial domain orthogonally. GRID2D/3D generates composite grid systems by patching together two or more single grid systems. The patching can be discontinuous or continuous. For continuous composite grid systems, the grid lines are continuous and differentiable everywhere up to the second-order except at interfaces where different single grid systems meet. At interfaces where different single grid systems meet, the grid lines are only differentiable up to the first-order. For 2-D spatial domains, the boundary curves are described by using either cubic or tension spline interpolation. For 3-D spatial domains, the boundary surfaces are described by using either linear Coon's interpolation, bi-hyperbolic spline interpolation, or a new technique referred to as 3-D bi-directional Hermite interpolation. Since grid systems generated by algebraic methods can have grid lines that overlap one another, GRID2D/3D contains a graphics package for evaluating the grid systems generated. With the graphics package, the user can generate grid systems in an interactive manner with the grid generation part of GRID2D/3D. GRID2D/3D is written in FORTRAN 77 and can be run on any IBM PC, XT, or AT compatible computer. In order to use GRID2D/3D on workstations or mainframe computers, some minor modifications must be made in the graphics part of the program; no
Transonic wing analysis using advanced computational methods
NASA Technical Reports Server (NTRS)
Henne, P. A.; Hicks, R. M.
1978-01-01
This paper discusses the application of three-dimensional computational transonic flow methods to several different types of transport wing designs. The purpose of these applications is to evaluate the basic accuracy and limitations associated with such numerical methods. The use of such computational methods for practical engineering problems can only be justified after favorable evaluations are completed. The paper summarizes a study of both the small-disturbance and the full potential technique for computing three-dimensional transonic flows. Computed three-dimensional results are compared to both experimental measurements and theoretical results. Comparisons are made not only of pressure distributions but also of lift and drag forces. Transonic drag rise characteristics are compared. Three-dimensional pressure distributions and aerodynamic forces, computed from the full potential solution, compare reasonably well with experimental results for a wide range of configurations and flow conditions.
Schulte, Friederike A; Lambers, Floor M; Kuhn, Gisela; Müller, Ralph
2011-03-01
Bone is a living tissue able to adapt its structure to external influences such as altered mechanical loading. This adaptation process is governed by two distinct cell types: bone-forming cells called osteoblasts and bone-resorbing cells called osteoclasts. It is therefore of particular interest to have quantitative access to the outcomes of bone formation and resorption separately. This article presents a non-invasive three-dimensional technique to directly extract bone formation and resorption parameters from time-lapsed in vivo micro-computed tomography scans. This includes parameters such as Mineralizing Surface (MS), Mineral Apposition Rate (MAR), and Bone Formation Rate (BFR), which were defined in accordance to the current nomenclature of dynamic histomorphometry. Due to the time-lapsed and non-destructive nature of in vivo micro-computed tomography, not only formation but also resorption can now be assessed quantitatively and time-dependent parameters Eroded Surface (ES) as well as newly defined indices Mineral Resorption Rate (MRR) and Bone Resorption Rate (BRR) are introduced. For validation purposes, dynamic formation parameters were compared to the traditional quantitative measures of dynamic histomorphometry, where MAR correlated with R = 0.68 and MS with R = 0.78 (p < 0.05). Reproducibility was assessed in 8 samples that were scanned 5 times and errors ranged from 0.9% (MRR) to 6.6% (BRR). Furthermore, the new parameters were applied to a murine in vivo loading model. A comparison of directly extracted parameters between formation and resorption within each animal revealed that in the control group, i.e., during normal remodeling, MAR was significantly lower than MRR (p < 0.01), whereas MS compared to ES was significantly higher (p < 0.0001). This implies that normal remodeling seems to take place by many small formation packets and few but large resorption volumes. After 4 weeks of mechanical loading, newly extracted trabecular BFR and MS were
Han, Chengzong; Liu, Zhongming; Zhang, Xin; Pogwizd, Steven; He, Bin
2009-01-01
Three-dimensional (3-D) cardiac activation imaging (3-DCAI) is a recently developed technique that aims at imaging the activation sequence throughout the 3-D volume of myocardium. 3-DCAI entails the modeling and estimation of the cardiac equivalent current density (ECD) distribution from which the local activation time within myocardium is determined as the time point with the peak amplitude of local ECD estimates. In this paper, we report, for the first time, an experimental study of the performance and applicability of 3-DCAI as judged by measured 3-D cardiac activation sequence using 3-D intra-cardiac mapping, in a group of 4 healthy rabbits during ventricular pacing. During the experiments, the body surface potentials and the intramural bipolar electrical recordings were simultaneously measured in a closed-chest condition to allow for a rigorous evaluation of the noninvasive 3-DCAI algorithm using the intra-cardiac mapping. The ventricular activation sequence non-invasively imaged from the body surface measurements by using 3-DCAI was generally in agreement with that obtained from the invasive intra-cardiac recordings. The overall difference between them, quantified as the root mean square (RMS) error, was 7.42±0.61 ms, and the normalized difference, quantified as the relative error (RE), was 0.24±0.03. The distance from the reconstructed site of initial activation to the actual pacing site, defined as the localization error (LE), was 5.47±1.57 mm. In addition, computer simulations were conducted to provide additional assessment of the performance of the 3-DCAI algorithm using a realistic-geometry rabbit heart-torso model. Averaged over 9 pacing sites, the RE and LE were 0.20±0.07 and 4.56±1.12 mm, respectively, for single-pacing, when 20 μV Gaussian white noise was added to the body surface potentials at 53 body surface locations. Averaged over 8 pairs of dual pacing, the RE was 0.25±0.06 for 20 μV additive noise. The present results obtained through
Chang, Jessica B; Small, Kevin H; Choi, Mihye; Karp, Nolan S
2015-05-01
Three-dimensional surface imaging has gained clinical acceptance in plastic and reconstructive surgery. In contrast to computed tomography/magnetic resonance imaging, three-dimensional surface imaging relies on triangulation in stereophotography to measure surface x, y, and z coordinates. This study reviews the past, present, and future directions of three-dimensional topographic imaging in plastic surgery. Historically, three-dimensional imaging technology was first used in a clinical setting in 1944 to diagnose orthodontologic conditions. Karlan established its use in the field of plastic surgery in 1979, analyzing contours and documenting facial asymmetries. Present use of three-dimensional surface imaging has focused on standardizing patient topographic measurements to enhance preoperative planning and to improve postoperative outcomes. Various measurements (e.g., volume, surface area, vector distance, curvature) have been applied to breast, body, and facial topography to augment patient analysis. Despite the rapid progression of the clinical applications of three-dimensional imaging, current use of this technology is focused on the surgeon's perspective and secondarily the patient's perspective. Advancements in patient simulation may improve patient-physician communication, education, and satisfaction. However, a communal database of three-dimensional surface images integrated with emerging three-dimensional printing and portable information technology will validate measurements and strengthen preoperative planning and postoperative outcomes. Three-dimensional surface imaging is a useful adjunct to plastic and reconstructive surgery practices and standardizes measurements to create objectivity in a subjective field. Key improvements in three-dimensional imaging technology may significantly enhance the quality of plastic and reconstructive surgery in the near future. PMID:25835245
Three-dimensional laser microvision.
Shimotahira, H; Iizuka, K; Chu, S C; Wah, C; Costen, F; Yoshikuni, Y
2001-04-10
A three-dimensional (3-D) optical imaging system offering high resolution in all three dimensions, requiring minimum manipulation and capable of real-time operation, is presented. The system derives its capabilities from use of the superstructure grating laser source in the implementation of a laser step frequency radar for depth information acquisition. A synthetic aperture radar technique was also used to further enhance its lateral resolution as well as extend the depth of focus. High-speed operation was made possible by a dual computer system consisting of a host and a remote microcomputer supported by a dual-channel Small Computer System Interface parallel data transfer system. The system is capable of operating near real time. The 3-D display of a tunneling diode, a microwave integrated circuit, and a see-through image taken by the system operating near real time are included. The depth resolution is 40 mum; lateral resolution with a synthetic aperture approach is a fraction of a micrometer and that without it is approximately 10 mum. PMID:18357177
Lee, Jae-Won; Kim, Moon-Key
2013-01-01
Three-dimensional (3D) computed tomography image models are helpful in reproducing the maxillofacial area; however, they do not necessarily provide an accurate representation of dental occlusion and the state of the teeth. Recent efforts have focused on improvement of dental imaging by replacement of computed tomography with other detailed digital images. Unfortunately, despite the advantages of medical simulation software in dentofacial analysis, diagnosis, and surgical simulation, it lacks adequate registration tools. Following up on our previous report on orthognathic simulation surgery using computer-aided design/computer-aided manufacturing (CAD/CAM) software, we recently used the registration functions of a CAD/CAM platform in conjunction with surgical simulation software. Therefore, we would like to introduce a new technique, which involves use of the registration functions of CAD/CAM software followed by transfer of the images into medical simulation software. This technique may be applicable when using various registration function tools from different software platforms. PMID:24471043
Kang, Sang-Hoon; Lee, Jae-Won; Kim, Moon-Key
2013-08-01
Three-dimensional (3D) computed tomography image models are helpful in reproducing the maxillofacial area; however, they do not necessarily provide an accurate representation of dental occlusion and the state of the teeth. Recent efforts have focused on improvement of dental imaging by replacement of computed tomography with other detailed digital images. Unfortunately, despite the advantages of medical simulation software in dentofacial analysis, diagnosis, and surgical simulation, it lacks adequate registration tools. Following up on our previous report on orthognathic simulation surgery using computer-aided design/computer-aided manufacturing (CAD/CAM) software, we recently used the registration functions of a CAD/CAM platform in conjunction with surgical simulation software. Therefore, we would like to introduce a new technique, which involves use of the registration functions of CAD/CAM software followed by transfer of the images into medical simulation software. This technique may be applicable when using various registration function tools from different software platforms. PMID:24471043
Advances and challenges in computational plasma science
NASA Astrophysics Data System (ADS)
Tang, W. M.
2005-02-01
Scientific simulation, which provides a natural bridge between theory and experiment, is an essential tool for understanding complex plasma behaviour. Recent advances in simulations of magnetically confined plasmas are reviewed in this paper, with illustrative examples, chosen from associated research areas such as microturbulence, magnetohydrodynamics and other topics. Progress has been stimulated, in particular, by the exponential growth of computer speed along with significant improvements in computer technology. The advances in both particle and fluid simulations of fine-scale turbulence and large-scale dynamics have produced increasingly good agreement between experimental observations and computational modelling. This was enabled by two key factors: (a) innovative advances in analytic and computational methods for developing reduced descriptions of physics phenomena spanning widely disparate temporal and spatial scales and (b) access to powerful new computational resources. Excellent progress has been made in developing codes for which computer run-time and problem-size scale well with the number of processors on massively parallel processors (MPPs). Examples include the effective usage of the full power of multi-teraflop (multi-trillion floating point computations per second) MPPs to produce three-dimensional, general geometry, nonlinear particle simulations that have accelerated advances in understanding the nature of turbulence self-regulation by zonal flows. These calculations, which typically utilized billions of particles for thousands of time-steps, would not have been possible without access to powerful present generation MPP computers and the associated diagnostic and visualization capabilities. In looking towards the future, the current results from advanced simulations provide great encouragement for being able to include increasingly realistic dynamics to enable deeper physics insights into plasmas in both natural and laboratory environments. This
Three-dimensional display technologies
Geng, Jason
2014-01-01
The physical world around us is three-dimensional (3D), yet traditional display devices can show only two-dimensional (2D) flat images that lack depth (i.e., the third dimension) information. This fundamental restriction greatly limits our ability to perceive and to understand the complexity of real-world objects. Nearly 50% of the capability of the human brain is devoted to processing visual information [Human Anatomy & Physiology (Pearson, 2012)]. Flat images and 2D displays do not harness the brain’s power effectively. With rapid advances in the electronics, optics, laser, and photonics fields, true 3D display technologies are making their way into the marketplace. 3D movies, 3D TV, 3D mobile devices, and 3D games have increasingly demanded true 3D display with no eyeglasses (autostereoscopic). Therefore, it would be very beneficial to readers of this journal to have a systematic review of state-of-the-art 3D display technologies. PMID:25530827
Three-Dimensional Schlieren Measurements
NASA Astrophysics Data System (ADS)
Sutherland, Bruce; Cochrane, Andrea
2004-11-01
Schlieren systems visualise disturbances that change the index of refraction of a fluid, for example due to temperature or salinity disturbances. `Synthetic schlieren' refers to a recent advance in which these disturbances are visualised with a digital camera and image-processing technology rather than the classical use of parabolic mirrors and a knife-edge. In a typical setup, light from an image of horizontal lines or dots passes almost horizontally through the test section of a fluid to a CCD camera. Refractive index disturbances distort the image and digital comparison of successive images reveals the plan-form structure and time evolution of the disturbances. If the disturbance is effectively two-dimensional, meaning that it is uniform across the line-of-sight of the camera, then its magnitude as well as its structure can measured through simple inversion of an algebraic equation. If the structure is axisymmetric with rotation-axis perpendicular to the line of sight, the magnitude of the disturbance can be measured through inversion of a non-singular square matrix. Here we report upon the extension of this work toward measuring the magnitude of a fully three-dimensional disturbance. This is done by analysing images from two perspectives through the test section and using inversion tomography techniques to reconstruct the disturbance field. The results are tested against theoretical predictions and experimental measurements.
NASA Astrophysics Data System (ADS)
Winkler, T.; Dai, X. Y.; Mielke, G.; Vogt, S.; Buechner, H.; Schantz, J. T.; Harder, Y.; Machens, H. G.; Morlock, M. M.; Schilling, A. F.
2014-04-01
The commonly applied cell-based, two-dimensional (2D) in vitro resorption assays for biomaterials are limited in a variety of cases, including high initial roughness of material surface, uncontrollable solubilization (or resorption) of the entire material surface, or complex three-dimensional (3D) structure of the bioactive material itself. All these make the accurate assessment and successful selection of the optimal bone substitute material difficult. In vivo, micro-computed tomography (micro-CT) has been widely applied for the analysis of bone physiology and pathology, as well as for the 3D analysis of scaffolds for bone tissue engineering. In this study, we show that micro-CT can also be applied for the in vitro analysis of osteoclast-mediated resorption of biomaterials. For our experiments, we chose a calcium salt-composite (composite of calcium sulphate (CSC), calcium carbonate, glycerin-1,2,3-tripalmiate), which evades common 2D in vitro resorption analysis as a result of its high surface roughness and material composition. Human osteoclasts were differentiated from precursor cells on the surface of the material for 28 days. Cells were analyzed for expression of tartrate-resistant acid phosphatase 5b (TRAP5b), multinuclearity, and size. Volumetric analysis of resorption was performed by micro-CT. Multinucleated osteoclasts developed on the surface of the material. TRAP5b expression of the cells on CSC was comparable with TRAP5b expression of cells cultivated on dentin for the first 3 weeks of culture. At day 28, TRAP5b expression, cell number, and size of the TRAP+ cells were reduced on the CSC when compared with cells on dentin. Volumetric anaylsis by micro-CT showed a strong cellular effect on resorption of CSC. We consider micro-CT to be a promising technique for 3D quantification of cell-based resorption that will allow the study of cellular resorption of materials in vitro, which were up to now confined to animal experimental analysis.
Boda-Heggemann, Judit Koehler, Frederick Marc; Kuepper, Beate; Wolff, Dirk; Wertz, Hansjoerg; Mai, Sabine; Hesser, Juergen; Lohr, Frank; Wenz, Frederik
2008-03-15
Purpose: To assess the accuracy of ultrasound-based repositioning (BAT) before prostate radiation with fiducial-based three-dimensional matching with cone-beam computed tomography (CBCT). Patients and Methods: Fifty-four positionings in 8 patients with {sup 125}I seeds/intraprostatic calcifications as fiducials were evaluated. Patients were initially positioned according to skin marks and after this according to bony structures based on CBCT. Prostate position correction was then performed with BAT. Residual error after repositioning based on skin marks, bony anatomy, and BAT was estimated by a second CBCT based on user-independent automatic fiducial registration. Results: Overall mean value (MV {+-} SD) residual error after BAT based on fiducial registration by CBCT was 0.7 {+-} 1.7 mm in x (group systematic error [M] = 0.5 mm; SD of systematic error [{sigma}] = 0.8 mm; SD of random error [{sigma}] = 1.4 mm), 0.9 {+-} 3.3 mm in y (M = 0.5 mm, {sigma} = 2.2 mm, {sigma} = 2.8 mm), and -1.7 {+-} 3.4 mm in z (M = -1.7 mm, {sigma} = 2.3 mm, {sigma} = 3.0 mm) directions, whereas residual error relative to positioning based on skin marks was 2.1 {+-} 4.6 mm in x (M = 2.6 mm, {sigma} = 3.3 mm, {sigma} = 3.9 mm), -4.8 {+-} 8.5 mm in y (M = -4.4 mm, {sigma} = 3.7 mm, {sigma} = 6.7 mm), and -5.2 {+-} 3.6 mm in z (M = -4.8 mm, {sigma} = 1.7 mm, {sigma} = 3.5mm) directions and relative to positioning based on bony anatomy was 0 {+-} 1.8 mm in x (M = 0.2 mm, {sigma} = 0.9 mm, {sigma} = 1.1 mm), -3.5 {+-} 6.8 mm in y (M = -3.0 mm, {sigma} = 1.8 mm, {sigma} = 3.7 mm), and -1.9 {+-} 5.2 mm in z (M = -2.0 mm, {sigma} = 1.3 mm, {sigma} = 4.0 mm) directions. Conclusions: BAT improved the daily repositioning accuracy over skin marks or even bony anatomy. The results obtained with BAT are within the precision of extracranial stereotactic procedures and represent values that can be achieved with several users with different education levels. If sonographic visibility is insufficient
Tilakchand, Mahima; Jain, Abhishek; Naik, Balaram
2016-01-01
Aim: The purpose of this study was to evaluate the three-dimensional expansion of Gutta-percha (GP), at various powder/liquid ratios, of a zinc oxide-eugenol (ZOE)-based sealer using spiral computed tomography (SCT). Materials and Methods: Thirty-five freshly extracted human mandibular premolars were selected for this study. Cleaning and shaping were performed in all the teeth initially with hand K-files up to #25 and finally with RaCe rotary instruments (25/06). Teeth were randomly divided into five groups of 7 teeth each. Specimens were scanned using SCT. They were then viewed both cross-sectionally and longitudinally, with a constant thickness of 1 mm/slice. The volume of root canal in each tooth was estimated. Obturation was performed by GP points (25/04) and ZOE-based root canal sealer in all groups with different powder-liquid ratio. Groups 1, 2, 3, and 4, had powder/liquid ratio of 1:1, 1:2, 1:3, and 1:4, respectively, while in the control group, no sealer was used. The obturation was performed by sealer coated single cone GP. A second SCT scan was performed to determine the volume of GP and sealer in all four groups 1 day after obturation. The third and fourth SCT scans were taken 7 and 30 days after obturation, respectively. The mean volume of GP per group was calculated. Data were statistically analyzed using one-way ANOVA. Inter-group comparisons were done using Scheffe post hoc multiple comparisons test. Results: All groups with sealer showed expansion of GP at both 7th day and 30th day, which was statistically significant from the GP volume at 1st day. Groups 2 and 3 with powder/liquid ratio of 1:2 and 1:3 gave the highest mean volume values during 30 days period and showed significant expansion in comparison with Groups 1 and 4 with powder/liquid ratio of 1:1 and 1:4, respectively. Conclusion: Increasing the ratio of eugenol in sealer resulted in the volumetric expansion of GP. However, further studies should be performed to confirm the expansion of
NASA Technical Reports Server (NTRS)
Vadyak, J.; Hoffman, J. D.; Bishop, A. R.
1978-01-01
The calculation procedure is based on the method of characteristics for steady three-dimensional flow. The bow shock wave and the internal shock wave system were computed using a discrete shock wave fitting procedure. The general structure of the computer program is discussed, and a brief description of each subroutine is given. All program input parameters are defined, and a brief discussion on interpretation of the output is provided. A number of sample cases, complete with data deck listings, are presented.
Farzad Rahnema
2009-11-12
This project has resulted in a highly efficient method that has been shown to provide accurate solutions to a variety of 2D and 3D reactor problems. The goal of this project was to develop (1) an accurate and efficient three-dimensional whole-core neutronics method with the following features: based sollely on transport theory, does not require the use of cross-section homogenization, contains a highly accurate and self-consistent global flux reconstruction procedure, and is applicable to large, heterogeneous reactor models, and to (2) create new numerical benchmark problems for code cross-comparison.
Dynamic Three-Dimensional Echocardiography
NASA Astrophysics Data System (ADS)
Matsusaka, Katsuhiko; Doi, Motonori; Oshiro, Osamu; Chihara, Kunihiro
2000-08-01
Conventional three-dimensional (3D) ultrasound imaging equipment for diagnosis requires much time to reconstruct 3D images or fix the view point for observing the 3D image. Thus, it is inconvenient for cardiac diagnosis. In this paper, we propose a new dynamic 3D echocardiography system. The system produces 3D images in real-time and permits changes in view point. This system consists of ultrasound diagnostic equipment, a digitizer and a computer. B-mode images are projected to a virtual 3D space by referring to the position of the probe of the ultrasound diagnosis equipment. The position is obtained by the digitizer to which the ultrasound probe is attached. The 3D cardiac image is constructed from B-mode images obtained simultaneously in the cardiac cycle. To obtain the same moment of heartbeat in the cardiac cycle, this system uses the electrocardiography derived from the diagnosis equipment. The 3D images, which show various scenes of the stage of heartbeat action, are displayed sequentially. The doctor can observe 3D images cut in any plane by pushing a button of the digitizer and zooming with the keyboard. We evaluated our prototype system by observation of a mitral valve in motion.
Generating Three-Dimensional Grids About Anything
NASA Technical Reports Server (NTRS)
Sorenson, Reese L.
1991-01-01
Three-Dimensional Grids About Anything by Poisson's Equation (3DGRAPE) computer program designed to make computational grids in or about almost any shape. Generated by solution of Poisson's differential equations in three dimensions. Program automatically finds its own values for inhomogeneous terms giving near-orthogonality and controlled grid-cell height at boundaries. Grids generated applied to both viscous and inviscid aerodynamic problems, and to problems in other areas of fluid dynamics. Written in 100 percent FORTRAN 77.
Guyomarc'h, Pierre; Santos, Frédéric; Dutailly, Bruno; Desbarats, Pascal; Bou, Christophe; Coqueugniot, Hélène
2012-06-10
Digital investigation of anthropological material through computed tomography (CT) offers several new opportunities in morphometrics. However, an object measured with computer-assisted methods does not necessarily exactly match the original one. The scanning and surface reconstruction of the object induce some alterations, and data acquisition is prone to measurement uncertainty. The purpose of this research is to evaluate the intra- and inter-observers variations in medical CT scan measurements of a known-size phantom and two dry crania. Two software packages, AMIRA and Treatment and Increased Vision for Medical Imaging (TIVMI), which use different techniques of surface reconstructions, were compared. The mean difference between the measurements was lower for TIVMI, using an objective algorithm based on the half-maximum height (HMH) protocol in three dimensions (3D). AMIRA can induce up to a 4% error in known measurements and 5% uncertainty in dry skull measurements. This study emphasises the risk of object shape alteration in each step of its digitisation. PMID:22297143
Three-dimensional null point reconnection regimes
Priest, E. R.; Pontin, D. I.
2009-12-15
Recent advances in theory and computational experiments have shown the need to refine the previous categorization of magnetic reconnection at three-dimensional null points--points at which the magnetic field vanishes. We propose here a division into three different types, depending on the nature of the flow near the spine and fan of the null. The spine is an isolated field line which approaches the null (or recedes from it), while the fan is a surface of field lines which recede from it (or approach it). So-called torsional spine reconnection occurs when field lines in the vicinity of the fan rotate, with current becoming concentrated along the spine so that nearby field lines undergo rotational slippage. In torsional fan reconnection field lines near the spine rotate and create a current that is concentrated in the fan with a rotational flux mismatch and rotational slippage. In both of these regimes, the spine and fan are perpendicular and there is no flux transfer across spine or fan. The third regime, called spine-fan reconnection, is the most common in practice and combines elements of the previous spine and fan models. In this case, in response to a generic shearing motion, the null point collapses to form a current sheet that is focused at the null itself, in a sheet that locally spans both the spine and fan. In this regime the spine and fan are no longer perpendicular and there is flux transfer across both of them.
Three-Dimensional Printing Surgical Applications
Griffin, Michelle F.; Butler, Peter E.
2015-01-01
Introduction: Three-dimensional printing, a technology used for decades in the industrial field, gains a lot of attention in the medical field for its potential benefits. With advancement of desktop printers, this technology is accessible and a lot of research is going on in the medical field. Objective: To evaluate its application in surgical field, which may include but not limited to surgical planning, surgical education, implants, and prosthesis, which are the focus of this review. Methods: Research was conducted by searching PubMed, Web of science, and other reliable sources. We included original articles and excluded articles based on animals, those more than 10 years old, and those not in English. These articles were evaluated, and relevant studies were included in this review. Discussion: Three-dimensional printing shows a potential benefit in surgical application. Printed implants were used in patient in a few cases and show successful results; however, longer follow-up and more trials are needed. Surgical and medical education is believed to be more efficient with this technology than the current practice. Printed surgical instrument and surgical planning are also believed to improve with three-dimensional printing. Conclusion: Three-dimensional printing can be a very powerful tool in the near future, which can aid the medical field that is facing a lot of challenges and obstacles. However, despite the reported results, further research on larger samples and analytical measurements should be conducted to ensure this technology's impact on the practice. PMID:26301002
Wulff, W; Cheng, H S; Diamond, D J; Khatib-Rahbar, M
1984-01-01
This report documents the physical models and the numerical methods employed in the BWR systems code RAMONA-3B. The RAMONA-3B code simulates three-dimensional neutron kinetics and multichannel core hydraulics of nonhomogeneous, nonequilibrium two-phase flows. RAMONA-3B is programmed to calculate the steady and transient conditions in the main steam supply system for normal and abnormal operational transients, including the performances of plant control and protection systems. Presented are code capabilities and limitations, models and solution techniques, the results of development code assessment and suggestions for improving the code in the future.
Three-dimensional printing of the retina
Lorber, Barbara; Hsiao, Wen-Kai; Martin, Keith R.
2016-01-01
Purpose of review Biological three-dimensional printing has received a lot of media attention over recent years with advances made in printing cellular structures, including skin and heart tissue for transplantation. Although limitations exist in creating functioning organs with this method, the hope has been raised that creating a functional retina to cure blindness is within reach. The present review provides an update on the advances made toward this goal. Recent findings It has recently been shown that two types of retinal cells, retinal ganglion cells and glial cells, can be successfully printed using a piezoelectric inkjet printer. Importantly, the cells remained viable and did not change certain phenotypic features as a result of the printing process. In addition, recent advances in the creation of complex and viable three-dimensional cellular structures have been made. Summary Some first promising steps toward the creation of a functional retina have been taken. It now needs to be investigated whether recent findings can be extended to other cells of the retina, including those derived from human tissue, and if a complex and viable retinal structure can be created through three-dimensional printing. PMID:27045545
Three-dimensional silicon micromachining
NASA Astrophysics Data System (ADS)
Azimi, S.; Song, J.; Dang, Z. Y.; Liang, H. D.; Breese, M. B. H.
2012-11-01
A process for fabricating arbitrary-shaped, two- and three-dimensional silicon and porous silicon components has been developed, based on high-energy ion irradiation, such as 250 keV to 1 MeV protons and helium. Irradiation alters the hole current flow during subsequent electrochemical anodization, allowing the anodization rate to be slowed or stopped for low/high fluences. For moderate fluences the anodization rate is selectively stopped only at depths corresponding to the high defect density at the end of ion range, allowing true three-dimensional silicon machining. The use of this process in fields including optics, photonics, holography and nanoscale depth machining is reviewed.
Analysis of three-dimensional transonic compressors
NASA Technical Reports Server (NTRS)
Bourgeade, A.
1984-01-01
A method for computing the three-dimensional transonic flow around the blades of a compressor or of a propeller is given. The method is based on the use of the velocity potential, on the hypothesis that the flow is inviscid, irrotational and isentropic. The equation of the potential is solved in a transformed space such that the surface of the blade is mapped into a plane where the periodicity is implicit. This equation is in a nonconservative form and is solved with the help of a finite difference method using artificial time. A computer code is provided and some sample results are given in order to demonstrate the influence of three-dimensional effects and the blade's rotation.
Advanced computational research in materials processing for design and manufacturing
Zacharia, T.
1994-12-31
The computational requirements for design and manufacture of automotive components have seen dramatic increases for producing automobiles with three times the mileage. Automotive component design systems are becoming increasingly reliant on structural analysis requiring both overall larger analysis and more complex analyses, more three-dimensional analyses, larger model sizes, and routine consideration of transient and non-linear effects. Such analyses must be performed rapidly to minimize delays in the design and development process, which drives the need for parallel computing. This paper briefly describes advanced computational research in superplastic forming and automotive crash worthiness.
Three dimensional colorimetric assay assemblies
Charych, D.; Reichart, A.
2000-06-27
A direct assay is described using novel three-dimensional polymeric assemblies which change from a blue to red color when exposed to an analyte, in one case a flu virus. The assemblies are typically in the form of liposomes which can be maintained in a suspension, and show great intensity in their color changes. Their method of production is also described.
Three dimensional colorimetric assay assemblies
Charych, Deborah; Reichart, Anke
2000-01-01
A direct assay is described using novel three-dimensional polymeric assemblies which change from a blue to red color when exposed to an analyte, in one case a flu virus. The assemblies are typically in the form of liposomes which can be maintained in a suspension, and show great intensity in their color changes. Their method of production is also described.
Three-Dimensional Lissajous Figures.
ERIC Educational Resources Information Center
D'Mura, John M.
1989-01-01
Described is a mechanically driven device for generating three-dimensional harmonic space figures with different frequencies and phase angles on the X, Y, and Z axes. Discussed are apparatus, viewing stereo pairs, equations of motion, and using space figures in classroom. (YP)
Biffle, J.H.
1993-02-01
JAC3D is a three-dimensional finite element program designed to solve quasi-static nonlinear mechanics problems. A set of continuum equations describes the nonlinear mechanics involving large rotation and strain. A nonlinear conjugate gradient method is used to solve the equation. The method is implemented in a three-dimensional setting with various methods for accelerating convergence. Sliding interface logic is also implemented. An eight-node Lagrangian uniform strain element is used with hourglass stiffness to control the zero-energy modes. This report documents the elastic and isothermal elastic-plastic material model. Other material models, documented elsewhere, are also available. The program is vectorized for efficient performance on Cray computers. Sample problems described are the bending of a thin beam, the rotation of a unit cube, and the pressurization and thermal loading of a hollow sphere.
NASA Technical Reports Server (NTRS)
Dorney, Suzanne; Dorney, Daniel J.; Huber, Frank; Sheffler, David A.; Turner, James E. (Technical Monitor)
2001-01-01
The advent of advanced computer architectures and parallel computing have led to a revolutionary change in the design process for turbomachinery components. Two- and three-dimensional steady-state computational flow procedures are now routinely used in the early stages of design. Unsteady flow analyses, however, are just beginning to be incorporated into design systems. This paper outlines the transition of a three-dimensional unsteady viscous flow analysis from the research environment into the design environment. The test case used to demonstrate the analysis is the full turbine system (high-pressure turbine, inter-turbine duct and low-pressure turbine) from an advanced turboprop engine.
Using Three-Dimensional Interactive Graphics To Teach Equipment Procedures.
ERIC Educational Resources Information Center
Hamel, Cheryl J.; Ryan-Jones, David L.
1997-01-01
Focuses on how three-dimensional graphical and interactive features of computer-based instruction can enhance learning and support human cognition during technical training of equipment procedures. Presents guidelines for using three-dimensional interactive graphics to teach equipment procedures based on studies of the effects of graphics, motion,…
NASA Technical Reports Server (NTRS)
Saracino, G.; Greenberg, N. L.; Shiota, T.; Corsi, C.; Lamberti, C.; Thomas, J. D.
2002-01-01
Real-time three-dimensional echocardiography (RT3DE) is an innovative cardiac imaging modality. However, partly due to lack of user-friendly software, RT3DE has not been widely accepted as a clinical tool. The object of this study was to develop and implement a fast and interactive volume renderer of RT3DE datasets designed for a clinical environment where speed and simplicity are not secondary to accuracy. Thirty-six patients (20 regurgitation, 8 normal, 8 cardiomyopathy) were imaged using RT3DE. Using our newly developed software, all 3D data sets were rendered in real-time throughout the cardiac cycle and assessment of cardiac function and pathology was performed for each case. The real-time interactive volume visualization system is user friendly and instantly provides consistent and reliable 3D images without expensive workstations or dedicated hardware. We believe that this novel tool can be used clinically for dynamic visualization of cardiac anatomy.
Three-Dimensional Displays In The Future Flight Station
NASA Astrophysics Data System (ADS)
Bridges, Alan L.
1984-10-01
This review paper summarizes the development and applications of computer techniques for the representation of three-dimensional data in the future flight station. It covers the development of the Lockheed-NASA Advanced Concepts Flight Station (ACFS) research simulators. These simulators contain: A Pilot's Desk Flight Station (PDFS) with five 13- inch diagonal, color, cathode ray tubes on the main instrument panel; a computer-generated day and night visual system; a six-degree-of-freedom motion base; and a computer complex. This paper reviews current research, development, and evaluation of easily modifiable display systems and software requirements for three-dimensional displays that may be developed for the PDFS. This includes the analysis and development of a 3-D representation of the entire flight profile. This 3-D flight path, or "Highway-in-the-Sky", will utilize motion and perspective cues to tightly couple the human responses of the pilot to the aircraft control systems. The use of custom logic, e.g., graphics engines, may provide the processing power and architecture required for 3-D computer-generated imagery (CGI) or visual scene simulation (VSS). Diffraction or holographic head-up displays (HUDs) will also be integrated into the ACFS simulator to permit research on the requirements and use of these "out-the-window" projection systems. Future research may include the retrieval of high-resolution, perspective view terrain maps which could then be overlaid with current weather information or other selectable cultural features.
Pollock, David W.
1989-01-01
A particle tracking post-processing package was developed to compute three-dimensional path lines based on output from steady-state simulations obtained with the U.S. Geological Survey modular 3-dimensional finite difference groundwater flow model. The package consists of two FORTRAN 77 computer programs: (1) MODPATH, which calculates pathlines, and (2) MODPATH-PLOT, which presents results graphically. MODPATH uses a semi-analytical particle tracking scheme. The method is based on the assumption that each directional velocity component varies linearly within a grid cell in its own coordinate direction. This assumption allows an analytical expression to be obtained describing the flow path within a grid cell. Given the initial position of a particle anywhere in a cell, the coordinates of any other point along its path line within the cell, and the time of travel between them, can be computed directly. Data is input to MODPATH and MODPATH-PLOT through a combination of files and interactive dialogue. Examples of how to use MODPATH and MODPATH-PLOT are provided for a sample problem. Listings of the computer codes and detailed descriptions of input data format and program options are also presented. (Author 's abstract)
Simulation of complex three-dimensional flows
NASA Technical Reports Server (NTRS)
Diewert, G. S.; Rothmund, H. J.; Nakahashi, K.
1985-01-01
The concept of splitting is used extensively to simulate complex three dimensional flows on modern computer architectures. Used in all aspects, from initial grid generation to the determination of the final converged solution, splitting is used to enhance code vectorization, to permit solution driven grid adaption and grid enrichment, to permit the use of concurrent processing, and to enhance data flow through hierarchal memory systems. Three examples are used to illustrate these concepts to complex three dimensional flow fields: (1) interactive flow over a bump; (2) supersonic flow past a blunt based conical afterbody at incidence to a free stream and containing a centered propulsive jet; and (3) supersonic flow past a sharp leading edge delta wing at incidence to the free stream.