Pseudo three-dimensional modeling of particle-fuel packing using distinct element method
Yuki, Daisuke; Takata, Takashi; Yamaguchi, Akira
2007-01-01
Vibration-based packing of sphere-pac fuel is a key technology in a nuclear fuel manufacturing. In the production process of sphere-pac fuel, a Mixed Oxide (MOX) fuel is formed to spherical form and is packed in a cladding tube by adding a vibration force. In the present study, we have developed a numerical simulation method to investigate the behavior of the particles in a vibrated tube using the Distinct Element Method (DEM). In general, the DEM requires a significant computational cost. Therefore we propose a new approach in which a small particle can move through the space between three larger particles even in the two-dimensional simulation. We take into account an equivalent three-dimensional effect in the equations of motion. Thus it is named pseudo three-dimensional modeling. (author)
Application of the distinct element method to the analysis of the concrete members under impact
Masuya, Hiroshi; Kajikawa, Yasuo; Nakata, Yoshihiko
1994-01-01
In this paper, the distinct element method is applied to the analysis of the behavior of a structure under impact. At first, this method is applied to the one-dimensional wave propagation problem by comparing with the experimental results and the theoretical results. The effectiveness of this method is confirmed by including not only elastic behavior but also the fracture of a structural member. Second, this method is developed to two-dimensional problems to simulate the behavior of a simply supported beam under an impact load. Finally, it could be shown that this method is effective to simulate wide phenomena from elastic behavior to a fracture under impact. ((orig.))
Application of distinct element method to toppling failure of slopes
Ishida, Tsuyoshi; Hibino, Satoshi; Kitahara, Yoshihiro; Asai, Yoshiyuki.
1985-01-01
Recently, the stability of slopes during earthquakes has become to be an important engineering problem, especially in case of the earthquake-proof design of nuclear power plants. But, for fissured rock slopes, some problems are remained unresolved, because they can not be treated as continua. The authors have been investigating toppling failure of slopes, from a point of view which regards a fissured rock mass as an assemblage of rigid blocks. DEM (Distinct Element Method) proposed by Cundall (1974) seems to be very helpful to such a investigation. So, in this paper, the applicability of DEM to toppling failure of slopes is examined through the comparison between DEM results and theoretical or experimental results using 3 simple models. (author)
Application of distinct element method of toppling failure of slope
Ishida, Tsuyoshi; Hibino, Satoshi; Kitahara, Yoshihiro; Ito, Hiroshi
1984-01-01
The authors have pointed out, in the latest report, that DEM (Distinct Element Method) seems to be a very helpful numerical method to examine the stability of fissured rock slopes, in which toppling failure would occur during earthquakes. In this report, the applicability of DEM for such rock slopes is examined through the following comparisons between theoretical results and DEM results, referring Voegele's works (1982): (1) Stability of one block on a slope. (2) Failure of a rock block column composed of 10 same size rectangular blocks. (3) Cable force required to make a slope stable. Through above 3 comparisons, it seems that DEM give the reasonable results. Considering that these problems may not be treated by the other numerical methods such as FEM and so on, so DEM seems to be a very useful method for fissured rock slope analysis. (author)
Distinct element modelling of joint behavior in nearfield rock
Hoekmark, H.; Israelsson, J.
1991-09-01
The investigation reported here concerns numerical simulations of the behaviour of the jointed rock mass in the nearest surroundings Of a portion of a KBS3 type tunnel, including one deposition hole. Results from three-dimensional models are presented and compared to results obtained from previous investigations of two-dimensional models. The three-dimensional models and the previous two-dimensional models relate to conditions prevailing in and around the BMT drift in Stripa mine. In particular are the importance of conditions, implicitly assumed in two-dimensional models, regarding joint orientation and joint persistence, investigated. The evaluation of the results is focused on effects on joint apertures. The implications regarding rock permeability is discussed for a couple of cases. It is found that the real three-dimensional geometry is of great importance, and that the two-dimensional models in some cases tend to overestimate the magnitudes of inelastic joint displacements and associated aperture changes considerably, i.e. the real three-dimensional situation implies locking effects, that generally stabilizes the block assembly. It is recommended that further three-dimensional simulations should be performed to determine relevant ranges of alteration of fracture apertures, caused by excavation and thermal processes, and that fracture geometries, that are typical to virgin granitic rock, should be defined and used as input for these simulations. (au)
Distinct Element modeling of geophysical signatures during sinkhole collapse
Al-Halbouni, Djamil; Holohan, Eoghan P.; Taheri, Abbas; Dahm, Torsten
2017-04-01
A sinkhole forms due to the collapse of rocks or soil near the Earth's surface into an underground cavity. Such cavities represent large secondary pore spaces derived by dissolution and subrosion in the underground. By changing the stress field in the surrounding material, the growth of cavities can lead to a positive feedback, in which expansion and mechanical instability in the surrounding material increases or generates new secondary pore space (e.g. by fracturing), which in turn increases the cavity size, etc. A sinkhole forms due to the eventual subsidence or collapse of the overburden that becomes destabilized and fails all the way to the Earth's surface. Both natural processes like (sub)surface water movement and earthquakes, and human activities, such as mining, construction and groundwater extraction, intensify such feedbacks. The development of models for the mechanical interaction of a growing cavity and fracturing of its surrounding material, thus capturing related precursory geophysical signatures, has been limited, however. Here we report on the advances of a general, simplified approach to simulating cavity growth and sinkhole formation by using 2D Distinct Element Modeling (DEM) PFC5.0 software and thereby constraining pre-, syn- and post-collapse geophysical and geodetic signatures. This physically realistic approach allows for spontaneous cavity development and dislocation of rock mass to be simulated by bonded particle formulation of DEM. First, we present calibration and validation of our model. Surface subsidence above an instantaneously excavated circular cavity is tracked and compared with an incrementally increasing dissolution zone both for purely elastic and non-elastic material.This validation is important for the optimal choice of model dimensions and particles size with respect to simulation time. Second, a cavity growth approach is presented and compared to a well-documented case study, the deliberately intensified sinkhole collapse at
Distinct element method modeling of fracture behavior in near field rock
Hoekmark, H.
1990-12-01
This report concerns the numerical calculations of the behavior of the near field of a nuclear waste repository. The calculations were performed using the two-dimensional distinct element code UDEC. The distinct element method accounts specifically for discontinuities, e.g. fractures that intersect the model region. It is shown that, if an appropriate joint constitutive relation is applied, the calculated joint behavior can be brought in close agreement with empirically derived stress-strain relations. Three basic geometries are studied, namely a vertical tunnel section, a horizontal borehole section and a combination, i.e. a vertical section of tunnel and deposition hole. The effects of different processes and activities are investigated, e.g. effects of excavations, of thermal loads, of internal tunnel pressures and of pore pressures and fracture flow resulting from the hydraulic ground water pressure. The interpretation of the results concerns in particular joint behavior, especially joint openings, in the nearest surroundings of excavations and of thermally affected regions. The calculations show that joint shear and joint normal displacements induced by excavation and by thermal processes may be considerable, and that thermal cycles may result in residual joint aperture changes, especially in systems with loosely bound rock blocks. It is concluded that the UDEC code, when applied to problems that have a two-dimensional character, gives results that are probably quantitatively correct. The results appear to be strongly dependant on the detailed joint structure close to free boundaries such as tunnel walls, which indicated that the 3-D situation regarding joint orientation might have to be considered. It is recommended that 3-D calculations should be performed to verify and quantitatively interpret the 2-D results and to analyze situations that are actually three-dimensional. (au)
Hindle, D.; Malz, A.; Donndorf, S.; Kley, J.; Kopp, H.
2012-04-01
We develop a coupled numerical model for fluid flow in deforming sedimentary basins. We combine a distinct element method for large deformations of crustal materials, with a finite element method for fluid flow according to a diffusion type equation. The key question in such a model is how to simulate evolving permeabilities due to upper and possibly middle crustal deformation, and the coupled issue of how localisation of deformation in faults and shear zones is itself influenced by fluid flow and fluid pressure and vice versa. Currently our knowledge of these issues is restricted, even sketchy. There are a number of hypotheses, based partly on geological and isotope geochemical observations, such as "seismic pumping" models, and fluid induced weak décollement models for thrust sheet transport which have gained quite wide acceptance. Observations around thrusts at the present day have also often been interpreted as showing deformation induced permeability. However, combining all the physics of these processes into a numerical simulation is a complicated task given the ranges of, in particular time scales of the processes we infer to be operating based on our various observations. We start this task by using an elastic fracture relationship between normal stresses across distinct element contacts (which we consider to be the equivalent of discrete, sliding fractures) and their openness and hence their transmissivity. This relates the mechanical state of the distinct element system to a discrete permeability field. Further than that, the geometry of the mechanical system is used to provide boundary conditions for fluid flow in a diffusion equation which also incorporates the permeability field. The next question we address is how to achieve a feedback between fluid pressures and deformation. We try two approaches: one treats pore space in the DEM as real, and calculates the force exerted locally by fluids and adds this to the force balance of the model; another
Finite element solution of two dimensional time dependent heat equation
Maaz
1999-01-01
A Microsoft Windows based computer code, named FHEAT, has been developed for solving two dimensional heat problems in Cartesian and Cylindrical geometries. The programming language is Microsoft Visual Basic 3.0. The code makes use of Finite element formulation for spatial domain and Finite difference formulation for time domain. Presently the code is capable of solving two dimensional steady state and transient problems in xy- and rz-geometries. The code is capable excepting both triangular and rectangular elements. Validation and benchmarking was done against hand calculations and published results. (author)
Davenport, Ernest C.; Davison, Mark L.; Liou, Pey-Yan; Love, Quintin U.
2015-01-01
This article uses definitions provided by Cronbach in his seminal paper for coefficient a to show the concepts of reliability, dimensionality, and internal consistency are distinct but interrelated. The article begins with a critique of the definition of reliability and then explores mathematical properties of Cronbach's a. Internal consistency…
Selfish genetic elements favor the evolution of a distinction between soma and germline.
Johnson, Louise J
2008-08-01
Many multicellular organisms have evolved a dedicated germline. This can benefit the whole organism, but its advantages to genetic parasites have not been explored. Here I model the evolutionary success of a selfish element, such as a transposable element or endosymbiont, which is capable of creating or strengthening a germline-soma distinction in a primitively multicellular host, and find that it will always benefit the element to do so. Genes causing germline sequestration can therefore spread in a population even if germline sequestration is maladaptive for the host organism. Costly selfish elements are expected to survive only in sexual populations, so sexual species may experience an additional push toward germline-soma distinction, and hence toward cell differentiation and multicellularity.
Three dimensional finite element linear analysis of reinforced concrete structures
Inbasakaran, M.; Pandarinathan, V.G.; Krishnamoorthy, C.S.
1979-01-01
A twenty noded isoparametric reinforced concrete solid element for the three dimensional linear elastic stress analysis of reinforced concrete structures is presented. The reinforcement is directly included as an integral part of the element thus facilitating discretization of the structure independent of the orientation of reinforcement. Concrete stiffness is evaluated by taking 3 x 3 x 3 Gauss integration rule and steel stiffness is evaluated numerically by considering three Gaussian points along the length of reinforcement. The numerical integration for steel stiffness necessiates the conversion of global coordiantes of the Gaussian points to nondimensional local coordinates and this is done by Newton Raphson iterative method. Subroutines for the above formulation have been developed and added to SAP and STAP routines for solving the examples. The validity of the reinforced concrete element is verified by comparison of results from finite element analysis and analytical results. It is concluded that this finite element model provides a valuable analytical tool for the three dimensional elastic stress analysis of concrete structures like beams curved in plan and nuclear containment vessels. (orig.)
Wasserman, E A; Anderson, P A
1974-11-01
The learning by hungry pigeons of a discrimination between two successively presented compound visual stimuli was investigated using a two-key autoshaping procedure. Common and distinctive stimulus elements were simultaneously presented on separate keys and either followed by food delivery, S+, or not, S-. The subjects acquired both between-trial and within-trial discriminations. On S+ trials, pigeons pecked the distinctive stimulus more than the common stimulus; before responding ceased on S- trials, they pecked the common stimulus more than the distinctive one. Mastery of the within-display discrimination during S+ trials preceded mastery of the between-trials discrimination. These findings extend the Jenkins-Sainsbury analysis of discriminations based upon a single distinguishing feature to discriminations in which common and distinctive elements are associated with both the positive and negative discriminative stimuli. The similarity of these findings to other effects found in autoshaping-approach to signals that forecast reinforcement and withdrawal from signals that forecast nonreinforcement-is also discussed.
Wasserman, Edward A.; Anderson, Patricia A.
1974-01-01
The learning by hungry pigeons of a discrimination between two successively presented compound visual stimuli was investigated using a two-key autoshaping procedure. Common and distinctive stimulus elements were simultaneously presented on separate keys and either followed by food delivery, S+, or not, S−. The subjects acquired both between-trial and within-trial discriminations. On S+ trials, pigeons pecked the distinctive stimulus more than the common stimulus; before responding ceased on S− trials, they pecked the common stimulus more than the distinctive one. Mastery of the within-display discrimination during S+ trials preceded mastery of the between-trials discrimination. These findings extend the Jenkins-Sainsbury analysis of discriminations based upon a single distinguishing feature to discriminations in which common and distinctive elements are associated with both the positive and negative discriminative stimuli. The similarity of these findings to other effects found in autoshaping—approach to signals that forecast reinforcement and withdrawal from signals that forecast nonreinforcement—is also discussed. PMID:16811812
Autoshaping with common and distinctive stimulus elements, compact and dispersed arrays1
Sperling, Sally E.; Perkins, Mark E.
1979-01-01
Four groups of pigeons were trained with a standard autoshaping procedure in which a brief fixed-duration interval always followed by a grain delivery alternated with a longer variable-duration interval never associated with grain delivery. One of two stimuli was always presented during each interval. One of them contained three black dots and a black star on a green background; the other contained four black dots on a green background. The four elements of each stimulus were arranged in a more compact array for two groups and in a more dispersed array for the other two groups. Which of the two stimuli preceded grain delivery was counterbalanced within each pair of groups. The speed of occurrence of the first autoshaped peck was not affected by whether the stimulus containing the distinctive star element preceded grain delivery, but autoshaping was faster when the stimulus arrays were compact than when they were dispersed. During 560 response-independent training trials that followed the first autoshaped peck, this pattern reversed; both discriminative control over responding and the relative frequency of pecking the stimulus that preceded grain delivery were greater for the two groups where this stimulus contained the discriminative element than for the two groups where it contained only common elements. During subsequent testing with stimuli containing only a single element each, the distinctive feature was responded to proportionately more often by the two groups for which it had been an element of the stimulus preceding grain delivery than by the two groups for which it had been an element of the stimulus complex that never was associated with grain delivery. These data add further support to the hypothesis that the initial occurrence of autoshaped responding and its subsequent maintenance are not affected by the same variables. They also suggest that automaintenance is as sensitive as response-dependent training to the presence or absence of a distinctive
Autoshaping with common and distinctive stimulus elements, compact and dispersed arrays.
Sperling, S E; Perkins, M E
1979-05-01
Four groups of pigeons were trained with a standard autoshaping procedure in which a brief fixed-duration interval always followed by a grain delivery alternated with a longer variable-duration interval never associated with grain delivery. One of two stimuli was always presented during each interval. One of them contained three black dots and a black star on a green background; the other contained four black dots on a green background. The four elements of each stimulus were arranged in a more compact array for two groups and in a more dispersed array for the other two groups. Which of the two stimuli preceded grain delivery was counterbalanced within each pair of groups. The speed of occurrence of the first autoshaped peck was not affected by whether the stimulus containing the distinctive star element preceded grain delivery, but autoshaping was faster when the stimulus arrays were compact than when they were dispersed. During 560 response-independent training trials that followed the first autoshaped peck, this pattern reversed; both discriminative control over responding and the relative frequency of pecking the stimulus that preceded grain delivery were greater for the two groups where this stimulus contained the discriminative element than for the two groups where it contained only common elements. During subsequent testing with stimuli containing only a single element each, the distinctive feature was responded to proportionately more often by the two groups for which it had been an element of the stimulus preceding grain delivery than by the two groups for which it had been an element of the stimulus complex that never was associated with grain delivery. These data add further support to the hypothesis that the initial occurrence of autoshaped responding and its subsequent maintenance are not affected by the same variables. They also suggest that automaintenance is as sensitive as response-dependent training to the presence or absence of a distinctive
Two-Dimensional Nonlinear Finite Element Analysis of CMC Microstructures
Mital, Subodh K.; Goldberg, Robert K.; Bonacuse, Peter J.
2012-01-01
A research program has been developed to quantify the effects of the microstructure of a woven ceramic matrix composite and its variability on the effective properties and response of the material. In order to characterize and quantify the variations in the microstructure of a five harness satin weave, chemical vapor infiltrated (CVI) SiC/SiC composite material, specimens were serially sectioned and polished to capture images that detailed the fiber tows, matrix, and porosity. Open source quantitative image analysis tools were then used to isolate the constituents, from which two dimensional finite element models were generated which approximated the actual specimen section geometry. A simplified elastic-plastic model, wherein all stress above yield is redistributed to lower stress regions, is used to approximate the progressive damage behavior for each of the composite constituents. Finite element analyses under in-plane tensile loading were performed to examine how the variability in the local microstructure affected the macroscopic stress-strain response of the material as well as the local initiation and progression of damage. The macroscopic stress-strain response appeared to be minimally affected by the variation in local microstructure, but the locations where damage initiated and propagated appeared to be linked to specific aspects of the local microstructure.
Long, Christopher M.; Nascarella, Marc A.; Valberg, Peter A.
2013-01-01
Airborne particles containing elemental carbon (EC) are currently at the forefront of scientific and regulatory scrutiny, including black carbon, carbon black, and engineered carbon-based nanomaterials, e.g., carbon nanotubes, fullerenes, and graphene. Scientists and regulators sometimes group these EC-containing particles together, for example, interchangeably using the terms carbon black and black carbon despite one being a manufactured product with well-controlled properties and the other being an undesired, incomplete-combustion byproduct with diverse properties. In this critical review, we synthesize information on the contrasting properties of EC-containing particles in order to highlight significant differences that can affect hazard potential. We demonstrate why carbon black should not be considered a model particle representative of either combustion soots or engineered carbon-based nanomaterials. Overall, scientific studies need to distinguish these highly different EC-containing particles with care and precision so as to forestall unwarranted extrapolation of properties, hazard potential, and study conclusions from one material to another. -- Highlights: •Major classes of elemental carbon-containing particles have distinct properties. •Despite similar names, carbon black should not be confused with black carbon. •Carbon black is distinguished by a high EC content and well-controlled properties. •Black carbon particles are characterized by their heterogenous properties. •Carbon black is not a model particle representative of engineered nanomaterials. -- This review demonstrates the significant physical and chemical distinctions between elemental carbon-containing particles e.g., carbon black, black carbon, and engineered nanomaterials
Three-dimensional discrete element method simulation of core disking
Wu, Shunchuan; Wu, Haoyan; Kemeny, John
2018-04-01
The phenomenon of core disking is commonly seen in deep drilling of highly stressed regions in the Earth's crust. Given its close relationship with the in situ stress state, the presence and features of core disking can be used to interpret the stresses when traditional in situ stress measuring techniques are not available. The core disking process was simulated in this paper using the three-dimensional discrete element method software PFC3D (particle flow code). In particular, PFC3D is used to examine the evolution of fracture initiation, propagation and coalescence associated with core disking under various stress states. In this paper, four unresolved problems concerning core disking are investigated with a series of numerical simulations. These simulations also provide some verification of existing results by other researchers: (1) Core disking occurs when the maximum principal stress is about 6.5 times the tensile strength. (2) For most stress situations, core disking occurs from the outer surface, except for the thrust faulting stress regime, where the fractures were found to initiate from the inner part. (3) The anisotropy of the two horizontal principal stresses has an effect on the core disking morphology. (4) The thickness of core disk has a positive relationship with radial stress and a negative relationship with axial stresses.
Geomechanical Simulations of CO2 Storage Integrity using the Livermore Distinct Element Method
Morris, J P; Johnson, S M; Friedmann, S J
2008-07-11
Large-scale carbon capture and sequestration (CCS) projects involving annual injections of millions of tons of CO{sub 2} are a key infrastructural element needed to substantially reduce greenhouse gas emissions. The large rate and volume of injection will induce pressure and stress gradients within the formation that could activate existing fractures and faults, or drive new fractures through the caprock. We will present results of an ongoing investigation to identify conditions that will activate existing fractures/faults or make new fractures within the caprock using the Livermore Distinct Element Code (LDEC). LDEC is a multiphysics code, developed at LLNL, capable of simulating dynamic fracture of rock masses under a range of conditions. As part of a recent project, LDEC has been extended to consider fault activation and dynamic fracture of rock masses due to pressurization of the pore-space. We will present several demonstrations of LDEC functionality and applications of LDEC to CO{sub 2} injection scenarios including injection into an extensively fractured rockmass. These examples highlight the advantages of explicitly including the geomechanical response of each interface within the rockmass. We present results from our investigations of Teapot Dome using LDEC to study the potential for fault activation during injection. Using this approach, we built finite element models of the rock masses surrounding bounding faults and explicitly simulated the compression and shear on the fault interface. A CO{sub 2} injection source was introduced and the area of fault activation was predicted as a function of injection rate. This work presents an approach where the interactions of all locations on the fault are considered in response to specific injection scenarios. For example, with LDEC, as regions of the fault fail, the shear load is taken up elsewhere on the fault. The results of this study are consistent with previous studies of Teapot Dome and indicate
hp Spectral element methods for three dimensional elliptic problems
This is the first of a series of papers devoted to the study of h-p spec- .... element functions defined on mesh elements in the new system of variables with a uni- ... the spectral element functions on these elements and give construction of the stability .... By Hm( ), we denote the usual Sobolev space of integer order m ≥ 0 ...
Laboratory and 3-D-distinct element analysis of failure mechanism of slope under external surcharge
Li, N.; Cheng, Y. M.
2014-09-01
Landslide is a major disaster resulting in considerable loss of human lives and property damages in hilly terrain in Hong Kong, China and many other countries. The factor of safety and the critical slip surface for slope stabilization are the main considerations for slope stability analysis in the past, while the detailed post-failure conditions of the slopes have not been considered in sufficient details. There are however increasing interest on the consequences after the initiation of failure which includes the development and propagation of the failure surfaces, the amount of failed mass and runoff and the affected region. To assess the development of slope failure in more details and to consider the potential danger of slopes after failure has initiated, the slope stability problem under external surcharge is analyzed by the distinct element method (DEM) and laboratory model test in the present research. A more refined study about the development of failure, microcosmic failure mechanism and the post-failure mechanism of slope will be carried out. The numerical modeling method and the various findings from the present work can provide an alternate method of analysis of slope failure which can give additional information not available from the classical methods of analysis.
Utilization of macrominerals and trace elements in pregnant heifers with distinct feed efficiencies.
Dias, R S; Montanholi, Y R; Lopez, S; Smith, B; Miller, S P; France, J
2016-07-01
The objective of the study was to evaluate utilization of dietary minerals and trace elements in pregnant heifers with distinct residual feed intakes (RFI). Feed intake, body weight (BW), and body composition traits were recorded in 36 crossbred heifers over a period of 37 wk, starting shortly after weaning at 8.3 (0.10; standard deviation) mo of age with an average BW of 276 (7.8) kg. Both BW and body composition were monitored regularly throughout the study, whereas individual feed intake was assessed during the last 84 d of the trial. Data recorded were used to calculate RFI for each heifer. Heifers were ranked based on RFI and assigned to high (n=14) or low (n=10) RFI groups. After the RFI study, 24 selected heifers [age 18.2 (0.14) mo; 87.5 (4.74) d in gestation; 497 (8.5) kg of BW] were used in an indirect digestibility trial (lignin as internal marker). Heifers were fed a ration containing corn silage, haylage, and a mineral premix in which Ca, P, K, Na, Mg, S, Cu, Fe, Mn, Mo, Se, Zn, and Co were provided in the diet according to National Research Council requirements of pregnant replacement heifers. The digestibility trial lasted 1 wk, during which samples of feces were gathered twice daily, and blood and liver biopsy samples were collected on the last day. We noted no significant differences between low- and high-RFI heifers in dry matter digestibility. Apparent absorption of Cu, Zn, and Mn was increased in heifers with low RFI, and apparent absorption of Co tended to be greater for these animals. Concentrations of macrominerals and trace elements in serum of pregnant heifers were similar for both groups except for Se, which was increased in the serum of low-RFI heifers. Liver concentrations of Cu, Fe, Mn, Mo, Se, and Zn did not differ between low- and high-RFI heifers. In conclusion, whereas improved absorption of some trace elements (Cu, Zn, Mn, and Co) and increased Se serum concentration appear to be associated with superior feed efficiency in pregnant
Two-dimensional isostatic meshes in the finite element method
Martínez Marín, Rubén; Samartín, Avelino
2002-01-01
In a Finite Element (FE) analysis of elastic solids several items are usually considered, namely, type and shape of the elements, number of nodes per element, node positions, FE mesh, total number of degrees of freedom (dot) among others. In this paper a method to improve a given FE mesh used for a particular analysis is described. For the improvement criterion different objective functions have been chosen (Total potential energy and Average quadratic error) and the number of nodes and dof's...
Finite element analysis of three dimensional crack growth by the use of a boundary element sub model
Lucht, Tore
2009-01-01
A new automated method to model non-planar three dimensional crack growth is proposed which combines the advantages of both the boundary element method and the finite element method. The proposed method links the two methods by a submodelling strategy in which the solution of a global finite...... element model containing an approximation of the crack is interpolated to a much smaller boundary element model containing a fine discretization of the real crack. The method is validated through several numerical comparisons and by comparison to crack growth measured in a test specimen for an engineering...
Distinct Element Method modelling of fold-related fractures in a multilayer sequence
Kaserer, Klemens; Schöpfer, Martin P. J.; Grasemann, Bernhard
2017-04-01
Natural fractures have a significant impact on the performance of hydrocarbon systems/reservoirs. In a multilayer sequence, both the fracture density within the individual layers and the type of fracture intersection with bedding contacts are key parameters controlling fluid pathways. In the present study the influence of layer stacking and interlayer friction on fracture density and connectivity within a folded sequence is systematically investigated using 2D Distinct Element Method modelling. Our numerical approach permits forward modelling of both fracture nucleation/propagation/arrest and (contemporaneous) frictional slip along bedding planes in a robust and mechanically sound manner. Folding of the multilayer sequence is achieved by enforcing constant curvature folding by means of a velocity boundary condition at the model base, while a constant overburden pressure is maintained at the model top. The modelling reveals that with high bedding plane friction the multilayer stack behaves mechanically as a single layer so that the neutral surface develops in centre of the sequence and fracture spacing is controlled by the total thickness of the folded sequence. In contrast, low bedding plane friction leads to decoupling of the individual layers (flexural slip folding) so that a neutral surface develops in the centre of each layer and fracture spacing is controlled by the thickness of the individual layers. The low interfacial friction models illustrate that stepping of fractures across bedding planes is a common process, which can however have two contrasting origins: The mechanical properties of the interface cause fracture stepping during fracture propagation. Originally through-going fractures are later offset by interfacial slip during folding. A combination of these two different origins may lead to (apparently) inconsistent fracture offsets across bedding planes within a flexural slip fold.
Deng, Yongbo; Korvink, Jan G
2016-05-01
This paper develops a topology optimization procedure for three-dimensional electromagnetic waves with an edge element-based finite-element method. In contrast to the two-dimensional case, three-dimensional electromagnetic waves must include an additional divergence-free condition for the field variables. The edge element-based finite-element method is used to both discretize the wave equations and enforce the divergence-free condition. For wave propagation described in terms of the magnetic field in the widely used class of non-magnetic materials, the divergence-free condition is imposed on the magnetic field. This naturally leads to a nodal topology optimization method. When wave propagation is described using the electric field, the divergence-free condition must be imposed on the electric displacement. In this case, the material in the design domain is assumed to be piecewise homogeneous to impose the divergence-free condition on the electric field. This results in an element-wise topology optimization algorithm. The topology optimization problems are regularized using a Helmholtz filter and a threshold projection method and are analysed using a continuous adjoint method. In order to ensure the applicability of the filter in the element-wise topology optimization version, a regularization method is presented to project the nodal into an element-wise physical density variable.
Yoo, Sung Min; Kim, Yoon Young
2007-01-01
This work is concerned with the topology optimization of three-dimensional cooling fins or heat sinks. Motivated by earlier success of the Internal Element Connectivity Method (I-ECP) method in two dimensional problems, the extension of I-ECP to three-dimensional problems is carried out. The main efforts were made to maintain the numerical trouble-free characteristics of I-ECP for full three-dimensional problems; a serious numerical problem appearing in thermal topology optimization is erroneous temperature undershooting. The effectiveness of the present implementation was checked through the design optimization of three-dimensional fins
Linear finite element method for one-dimensional diffusion problems
Brandao, Michele A.; Dominguez, Dany S.; Iglesias, Susana M., E-mail: micheleabrandao@gmail.com, E-mail: dany@labbi.uesc.br, E-mail: smiglesias@uesc.br [Universidade Estadual de Santa Cruz (LCC/DCET/UESC), Ilheus, BA (Brazil). Departamento de Ciencias Exatas e Tecnologicas. Laboratorio de Computacao Cientifica
2011-07-01
We describe in this paper the fundamentals of Linear Finite Element Method (LFEM) applied to one-speed diffusion problems in slab geometry. We present the mathematical formulation to solve eigenvalue and fixed source problems. First, we discretized a calculus domain using a finite set of elements. At this point, we obtain the spatial balance equations for zero order and first order spatial moments inside each element. Then, we introduce the linear auxiliary equations to approximate neutron flux and current inside the element and architect a numerical scheme to obtain the solution. We offer numerical results for fixed source typical model problems to illustrate the method's accuracy for coarse-mesh calculations in homogeneous and heterogeneous domains. Also, we compare the accuracy and computational performance of LFEM formulation with conventional Finite Difference Method (FDM). (author)
Leung, Wilson; Shaffer, Christopher D.; Reed, Laura K.; Smith, Sheryl T.; Barshop, William; Dirkes, William; Dothager, Matthew; Lee, Paul; Wong, Jeannette; Xiong, David; Yuan, Han; Bedard, James E. J.; Machone, Joshua F.; Patterson, Seantay D.; Price, Amber L.; Turner, Bryce A.; Robic, Srebrenka; Luippold, Erin K.; McCartha, Shannon R.; Walji, Tezin A.; Walker, Chelsea A.; Saville, Kenneth; Abrams, Marita K.; Armstrong, Andrew R.; Armstrong, William; Bailey, Robert J.; Barberi, Chelsea R.; Beck, Lauren R.; Blaker, Amanda L.; Blunden, Christopher E.; Brand, Jordan P.; Brock, Ethan J.; Brooks, Dana W.; Brown, Marie; Butzler, Sarah C.; Clark, Eric M.; Clark, Nicole B.; Collins, Ashley A.; Cotteleer, Rebecca J.; Cullimore, Peterson R.; Dawson, Seth G.; Docking, Carter T.; Dorsett, Sasha L.; Dougherty, Grace A.; Downey, Kaitlyn A.; Drake, Andrew P.; Earl, Erica K.; Floyd, Trevor G.; Forsyth, Joshua D.; Foust, Jonathan D.; Franchi, Spencer L.; Geary, James F.; Hanson, Cynthia K.; Harding, Taylor S.; Harris, Cameron B.; Heckman, Jonathan M.; Holderness, Heather L.; Howey, Nicole A.; Jacobs, Dontae A.; Jewell, Elizabeth S.; Kaisler, Maria; Karaska, Elizabeth A.; Kehoe, James L.; Koaches, Hannah C.; Koehler, Jessica; Koenig, Dana; Kujawski, Alexander J.; Kus, Jordan E.; Lammers, Jennifer A.; Leads, Rachel R.; Leatherman, Emily C.; Lippert, Rachel N.; Messenger, Gregory S.; Morrow, Adam T.; Newcomb, Victoria; Plasman, Haley J.; Potocny, Stephanie J.; Powers, Michelle K.; Reem, Rachel M.; Rennhack, Jonathan P.; Reynolds, Katherine R.; Reynolds, Lyndsey A.; Rhee, Dong K.; Rivard, Allyson B.; Ronk, Adam J.; Rooney, Meghan B.; Rubin, Lainey S.; Salbert, Luke R.; Saluja, Rasleen K.; Schauder, Taylor; Schneiter, Allison R.; Schulz, Robert W.; Smith, Karl E.; Spencer, Sarah; Swanson, Bryant R.; Tache, Melissa A.; Tewilliager, Ashley A.; Tilot, Amanda K.; VanEck, Eve; Villerot, Matthew M.; Vylonis, Megan B.; Watson, David T.; Wurzler, Juliana A.; Wysocki, Lauren M.; Yalamanchili, Monica; Zaborowicz, Matthew A.; Emerson, Julia A.; Ortiz, Carlos; Deuschle, Frederic J.; DiLorenzo, Lauren A.; Goeller, Katie L.; Macchi, Christopher R.; Muller, Sarah E.; Pasierb, Brittany D.; Sable, Joseph E.; Tucci, Jessica M.; Tynon, Marykathryn; Dunbar, David A.; Beken, Levent H.; Conturso, Alaina C.; Danner, Benjamin L.; DeMichele, Gabriella A.; Gonzales, Justin A.; Hammond, Maureen S.; Kelley, Colleen V.; Kelly, Elisabeth A.; Kulich, Danielle; Mageeney, Catherine M.; McCabe, Nikie L.; Newman, Alyssa M.; Spaeder, Lindsay A.; Tumminello, Richard A.; Revie, Dennis; Benson, Jonathon M.; Cristostomo, Michael C.; DaSilva, Paolo A.; Harker, Katherine S.; Jarrell, Jenifer N.; Jimenez, Luis A.; Katz, Brandon M.; Kennedy, William R.; Kolibas, Kimberly S.; LeBlanc, Mark T.; Nguyen, Trung T.; Nicolas, Daniel S.; Patao, Melissa D.; Patao, Shane M.; Rupley, Bryan J.; Sessions, Bridget J.; Weaver, Jennifer A.; Goodman, Anya L.; Alvendia, Erica L.; Baldassari, Shana M.; Brown, Ashley S.; Chase, Ian O.; Chen, Maida; Chiang, Scott; Cromwell, Avery B.; Custer, Ashley F.; DiTommaso, Tia M.; El-Adaimi, Jad; Goscinski, Nora C.; Grove, Ryan A.; Gutierrez, Nestor; Harnoto, Raechel S.; Hedeen, Heather; Hong, Emily L.; Hopkins, Barbara L.; Huerta, Vilma F.; Khoshabian, Colin; LaForge, Kristin M.; Lee, Cassidy T.; Lewis, Benjamin M.; Lydon, Anniken M.; Maniaci, Brian J.; Mitchell, Ryan D.; Morlock, Elaine V.; Morris, William M.; Naik, Priyanka; Olson, Nicole C.; Osterloh, Jeannette M.; Perez, Marcos A.; Presley, Jonathan D.; Randazzo, Matt J.; Regan, Melanie K.; Rossi, Franca G.; Smith, Melanie A.; Soliterman, Eugenia A.; Sparks, Ciani J.; Tran, Danny L.; Wan, Tiffany; Welker, Anne A.; Wong, Jeremy N.; Sreenivasan, Aparna; Youngblom, Jim; Adams, Andrew; Alldredge, Justin; Bryant, Ashley; Carranza, David; Cifelli, Alyssa; Coulson, Kevin; Debow, Calise; Delacruz, Noelle; Emerson, Charlene; Farrar, Cassandra; Foret, Don; Garibay, Edgar; Gooch, John; Heslop, Michelle; Kaur, Sukhjit; Khan, Ambreen; Kim, Van; Lamb, Travis; Lindbeck, Peter; Lucas, Gabi; Macias, Elizabeth; Martiniuc, Daniela; Mayorga, Lissett; Medina, Joseph; Membreno, Nelson; Messiah, Shady; Neufeld, Lacey; Nguyen, San Francisco; Nichols, Zachary; Odisho, George; Peterson, Daymon; Rodela, Laura; Rodriguez, Priscilla; Rodriguez, Vanessa; Ruiz, Jorge; Sherrill, Will; Silva, Valeria; Sparks, Jeri; Statton, Geeta; Townsend, Ashley; Valdez, Isabel; Waters, Mary; Westphal, Kyle; Winkler, Stacey; Zumkehr, Joannee; DeJong, Randall J.; Hoogewerf, Arlene J.; Ackerman, Cheri M.; Armistead, Isaac O.; Baatenburg, Lara; Borr, Matthew J.; Brouwer, Lindsay K.; Burkhart, Brandon J.; Bushhouse, Kelsey T.; Cesko, Lejla; Choi, Tiffany Y. Y.; Cohen, Heather; Damsteegt, Amanda M.; Darusz, Jess M.; Dauphin, Cory M.; Davis, Yelena P.; Diekema, Emily J.; Drewry, Melissa; Eisen, Michelle E. M.; Faber, Hayley M.; Faber, Katherine J.; Feenstra, Elizabeth; Felzer-Kim, Isabella T.; Hammond, Brandy L.; Hendriksma, Jesse; Herrold, Milton R.; Hilbrands, Julia A.; Howell, Emily J.; Jelgerhuis, Sarah A.; Jelsema, Timothy R.; Johnson, Benjamin K.; Jones, Kelly K.; Kim, Anna; Kooienga, Ross D.; Menyes, Erika E.; Nollet, Eric A.; Plescher, Brittany E.; Rios, Lindsay; Rose, Jenny L.; Schepers, Allison J.; Scott, Geoff; Smith, Joshua R.; Sterling, Allison M.; Tenney, Jenna C.; Uitvlugt, Chris; VanDyken, Rachel E.; VanderVennen, Marielle; Vue, Samantha; Kokan, Nighat P.; Agbley, Kwabea; Boham, Sampson K.; Broomfield, Daniel; Chapman, Kayla; Dobbe, Ali; Dobbe, Ian; Harrington, William; Ibrahem, Marwan; Kennedy, Andre; Koplinsky, Chad A.; Kubricky, Cassandra; Ladzekpo, Danielle; Pattison, Claire; Ramirez, Roman E.; Wande, Lucia; Woehlke, Sarah; Wawersik, Matthew; Kiernan, Elizabeth; Thompson, Jeffrey S.; Banker, Roxanne; Bartling, Justina R.; Bhatiya, Chinmoy I.; Boudoures, Anna L.; Christiansen, Lena; Fosselman, Daniel S.; French, Kristin M.; Gill, Ishwar S.; Havill, Jessen T.; Johnson, Jaelyn L.; Keny, Lauren J.; Kerber, John M.; Klett, Bethany M.; Kufel, Christina N.; May, Francis J.; Mecoli, Jonathan P.; Merry, Callie R.; Meyer, Lauren R.; Miller, Emily G.; Mullen, Gregory J.; Palozola, Katherine C.; Pfeil, Jacob J.; Thomas, Jessica G.; Verbofsky, Evan M.; Spana, Eric P.; Agarwalla, Anant; Chapman, Julia; Chlebina, Ben; Chong, Insun; Falk, I.N.; Fitzgibbons, John D.; Friedman, Harrison; Ighile, Osagie; Kim, Andrew J.; Knouse, Kristin A.; Kung, Faith; Mammo, Danny; Ng, Chun Leung; Nikam, Vinayak S.; Norton, Diana; Pham, Philip; Polk, Jessica W.; Prasad, Shreya; Rankin, Helen; Ratliff, Camille D.; Scala, Victoria; Schwartz, Nicholas U.; Shuen, Jessica A.; Xu, Amy; Xu, Thomas Q.; Zhang, Yi; Rosenwald, Anne G.; Burg, Martin G.; Adams, Stephanie J.; Baker, Morgan; Botsford, Bobbi; Brinkley, Briana; Brown, Carter; Emiah, Shadie; Enoch, Erica; Gier, Chad; Greenwell, Alyson; Hoogenboom, Lindsay; Matthews, Jordan E.; McDonald, Mitchell; Mercer, Amanda; Monsma, Nicholaus; Ostby, Kristine; Ramic, Alen; Shallman, Devon; Simon, Matthew; Spencer, Eric; Tomkins, Trisha; Wendland, Pete; Wylie, Anna; Wolyniak, Michael J.; Robertson, Gregory M.; Smith, Samuel I.; DiAngelo, Justin R.; Sassu, Eric D.; Bhalla, Satish C.; Sharif, Karim A.; Choeying, Tenzin; Macias, Jason S.; Sanusi, Fareed; Torchon, Karvyn; Bednarski, April E.; Alvarez, Consuelo J.; Davis, Kristen C.; Dunham, Carrie A.; Grantham, Alaina J.; Hare, Amber N.; Schottler, Jennifer; Scott, Zackary W.; Kuleck, Gary A.; Yu, Nicole S.; Kaehler, Marian M.; Jipp, Jacob; Overvoorde, Paul J.; Shoop, Elizabeth; Cyrankowski, Olivia; Hoover, Betsy; Kusner, Matt; Lin, Devry; Martinov, Tijana; Misch, Jonathan; Salzman, Garrett; Schiedermayer, Holly; Snavely, Michael; Zarrasola, Stephanie; Parrish, Susan; Baker, Atlee; Beckett, Alissa; Belella, Carissa; Bryant, Julie; Conrad, Turner; Fearnow, Adam; Gomez, Carolina; Herbstsomer, Robert A.; Hirsch, Sarah; Johnson, Christen; Jones, Melissa; Kabaso, Rita; Lemmon, Eric; Vieira, Carolina Marques dos Santos; McFarland, Darryl; McLaughlin, Christopher; Morgan, Abbie; Musokotwane, Sepo; Neutzling, William; Nietmann, Jana; Paluskievicz, Christina; Penn, Jessica; Peoples, Emily; Pozmanter, Caitlin; Reed, Emily; Rigby, Nichole; Schmidt, Lasse; Shelton, Micah; Shuford, Rebecca; Tirasawasdichai, Tiara; Undem, Blair; Urick, Damian; Vondy, Kayla; Yarrington, Bryan; Eckdahl, Todd T.; Poet, Jeffrey L.; Allen, Alica B.; Anderson, John E.; Barnett, Jason M.; Baumgardner, Jordan S.; Brown, Adam D.; Carney, Jordan E.; Chavez, Ramiro A.; Christgen, Shelbi L.; Christie, Jordan S.; Clary, Andrea N.; Conn, Michel A.; Cooper, Kristen M.; Crowley, Matt J.; Crowley, Samuel T.; Doty, Jennifer S.; Dow, Brian A.; Edwards, Curtis R.; Elder, Darcie D.; Fanning, John P.; Janssen, Bridget M.; Lambright, Anthony K.; Lane, Curtiss E.; Limle, Austin B.; Mazur, Tammy; McCracken, Marly R.; McDonough, Alexa M.; Melton, Amy D.; Minnick, Phillip J.; Musick, Adam E.; Newhart, William H.; Noynaert, Joseph W.; Ogden, Bradley J.; Sandusky, Michael W.; Schmuecker, Samantha M.; Shipman, Anna L.; Smith, Anna L.; Thomsen, Kristen M.; Unzicker, Matthew R.; Vernon, William B.; Winn, Wesley W.; Woyski, Dustin S.; Zhu, Xiao; Du, Chunguang; Ament, Caitlin; Aso, Soham; Bisogno, Laura Simone; Caronna, Jason; Fefelova, Nadezhda; Lopez, Lenin; Malkowitz, Lorraine; Marra, Jonathan; Menillo, Daniella; Obiorah, Ifeanyi; Onsarigo, Eric Nyabeta; Primus, Shekerah; Soos, Mahdi; Tare, Archana; Zidan, Ameer; Jones, Christopher J.; Aronhalt, Todd; Bellush, James M.; Burke, Christa; DeFazio, Steve; Does, Benjamin R.; Johnson, Todd D.; Keysock, Nicholas; Knudsen, Nelson H.; Messler, James; Myirski, Kevin; Rekai, Jade Lea; Rempe, Ryan Michael; Salgado, Michael S.; Stagaard, Erica; Starcher, Justin R.; Waggoner, Andrew W.; Yemelyanova, Anastasia K.; Hark, Amy T.; Bertolet, Anne; Kuschner, Cyrus E.; Parry, Kesley; Quach, Michael; Shantzer, Lindsey; Shaw, Mary E.; Smith, Mary A.; Glenn, Omolara; Mason, Portia; Williams, Charlotte; Key, S. Catherine Silver; Henry, Tyneshia C. P.; Johnson, Ashlee G.; White, Jackie X.; Haberman, Adam; Asinof, Sam; Drumm, Kelly; Freeburg, Trip; Safa, Nadia; Schultz, Darrin; Shevin, Yakov; Svoronos, Petros; Vuong, Tam; Wellinghoff, Jules; Hoopes, Laura L. M.; Chau, Kim M.; Ward, Alyssa; Regisford, E. Gloria C.; Augustine, LaJerald; Davis-Reyes, Brionna; Echendu, Vivienne; Hales, Jasmine; Ibarra, Sharon; Johnson, Lauriaun; Ovu, Steven; Braverman, John M.; Bahr, Thomas J.; Caesar, Nicole M.; Campana, Christopher; Cassidy, Daniel W.; Cognetti, Peter A.; English, Johnathan D.; Fadus, Matthew C.; Fick, Cameron N.; Freda, Philip J.; Hennessy, Bryan M.; Hockenberger, Kelsey; Jones, Jennifer K.; King, Jessica E.; Knob, Christopher R.; Kraftmann, Karen J.; Li, Linghui; Lupey, Lena N.; Minniti, Carl J.; Minton, Thomas F.; Moran, Joseph V.; Mudumbi, Krishna; Nordman, Elizabeth C.; Puetz, William J.; Robinson, Lauren M.; Rose, Thomas J.; Sweeney, Edward P.; Timko, Ashley S.; Paetkau, Don W.; Eisler, Heather L.; Aldrup, Megan E.; Bodenberg, Jessica M.; Cole, Mara G.; Deranek, Kelly M.; DeShetler, Megan; Dowd, Rose M.; Eckardt, Alexandra K.; Ehret, Sharon C.; Fese, Jessica; Garrett, Amanda D.; Kammrath, Anna; Kappes, Michelle L.; Light, Morgan R.; Meier, Anne C.; O’Rouke, Allison; Perella, Mallory; Ramsey, Kimberley; Ramthun, Jennifer R.; Reilly, Mary T.; Robinett, Deirdre; Rossi, Nadine L.; Schueler, Mary Grace; Shoemaker, Emma; Starkey, Kristin M.; Vetor, Ashley; Vrable, Abby; Chandrasekaran, Vidya; Beck, Christopher; Hatfield, Kristen R.; Herrick, Douglas A.; Khoury, Christopher B.; Lea, Charlotte; Louie, Christopher A.; Lowell, Shannon M.; Reynolds, Thomas J.; Schibler, Jeanine; Scoma, Alexandra H.; Smith-Gee, Maxwell T.; Tuberty, Sarah; Smith, Christopher D.; Lopilato, Jane E.; Hauke, Jeanette; Roecklein-Canfield, Jennifer A.; Corrielus, Maureen; Gilman, Hannah; Intriago, Stephanie; Maffa, Amanda; Rauf, Sabya A.; Thistle, Katrina; Trieu, Melissa; Winters, Jenifer; Yang, Bib; Hauser, Charles R.; Abusheikh, Tariq; Ashrawi, Yara; Benitez, Pedro; Boudreaux, Lauren R.; Bourland, Megan; Chavez, Miranda; Cruz, Samantha; Elliott, GiNell; Farek, Jesse R.; Flohr, Sarah; Flores, Amanda H.; Friedrichs, Chelsey; Fusco, Zach; Goodwin, Zane; Helmreich, Eric; Kiley, John; Knepper, John Mark; Langner, Christine; Martinez, Megan; Mendoza, Carlos; Naik, Monal; Ochoa, Andrea; Ragland, Nicolas; Raimey, England; Rathore, Sunil; Reza, Evangelina; Sadovsky, Griffin; Seydoux, Marie-Isabelle B.; Smith, Jonathan E.; Unruh, Anna K.; Velasquez, Vicente; Wolski, Matthew W.; Gosser, Yuying; Govind, Shubha; Clarke-Medley, Nicole; Guadron, Leslie; Lau, Dawn; Lu, Alvin; Mazzeo, Cheryl; Meghdari, Mariam; Ng, Simon; Pamnani, Brad; Plante, Olivia; Shum, Yuki Kwan Wa; Song, Roy; Johnson, Diana E.; Abdelnabi, Mai; Archambault, Alexi; Chamma, Norma; Gaur, Shailly; Hammett, Deborah; Kandahari, Adrese; Khayrullina, Guzal; Kumar, Sonali; Lawrence, Samantha; Madden, Nigel; Mandelbaum, Max; Milnthorp, Heather; Mohini, Shiv; Patel, Roshni; Peacock, Sarah J.; Perling, Emily; Quintana, Amber; Rahimi, Michael; Ramirez, Kristen; Singhal, Rishi; Weeks, Corinne; Wong, Tiffany; Gillis, Aubree T.; Moore, Zachary D.; Savell, Christopher D.; Watson, Reece; Mel, Stephanie F.; Anilkumar, Arjun A.; Bilinski, Paul; Castillo, Rostislav; Closser, Michael; Cruz, Nathalia M.; Dai, Tiffany; Garbagnati, Giancarlo F.; Horton, Lanor S.; Kim, Dongyeon; Lau, Joyce H.; Liu, James Z.; Mach, Sandy D.; Phan, Thu A.; Ren, Yi; Stapleton, Kenneth E.; Strelitz, Jean M.; Sunjed, Ray; Stamm, Joyce; Anderson, Morgan C.; Bonifield, Bethany Grace; Coomes, Daniel; Dillman, Adam; Durchholz, Elaine J.; Fafara-Thompson, Antoinette E.; Gross, Meleah J.; Gygi, Amber M.; Jackson, Lesley E.; Johnson, Amy; Kocsisova, Zuzana; Manghelli, Joshua L.; McNeil, Kylie; Murillo, Michael; Naylor, Kierstin L.; Neely, Jessica; Ogawa, Emmy E.; Rich, Ashley; Rogers, Anna; Spencer, J. Devin; Stemler, Kristina M.; Throm, Allison A.; Van Camp, Matt; Weihbrecht, Katie; Wiles, T. Aaron; Williams, Mallory A.; Williams, Matthew; Zoll, Kyle; Bailey, Cheryl; Zhou, Leming; Balthaser, Darla M.; Bashiri, Azita; Bower, Mindy E.; Florian, Kayla A.; Ghavam, Nazanin; Greiner-Sosanko, Elizabeth S.; Karim, Helmet; Mullen, Victor W.; Pelchen, Carly E.; Yenerall, Paul M.; Zhang, Jiayu; Rubin, Michael R.; Arias-Mejias, Suzette M.; Bermudez-Capo, Armando G.; Bernal-Vega, Gabriela V.; Colon-Vazquez, Mariela; Flores-Vazquez, Arelys; Gines-Rosario, Mariela; Llavona-Cartagena, Ivan G.; Martinez-Rodriguez, Javier O.; Ortiz-Fuentes, Lionel; Perez-Colomba, Eliezer O.; Perez-Otero, Joseph; Rivera, Elisandra; Rodriguez-Giron, Luke J.; Santiago-Sanabria, Arnaldo J.; Senquiz-Gonzalez, Andrea M.; delValle, Frank R. Soto; Vargas-Franco, Dorianmarie; Velázquez-Soto, Karla I.; Zambrana-Burgos, Joan D.; Martinez-Cruzado, Juan Carlos; Asencio-Zayas, Lillyann; Babilonia-Figueroa, Kevin; Beauchamp-Pérez, Francis D.; Belén-Rodríguez, Juliana; Bracero-Quiñones, Luciann; Burgos-Bula, Andrea P.; Collado-Méndez, Xavier A.; Colón-Cruz, Luis R.; Correa-Muller, Ana I.; Crooke-Rosado, Jonathan L.; Cruz-García, José M.; Defendini-Ávila, Marianna; Delgado-Peraza, Francheska M.; Feliciano-Cancela, Alex J.; Gónzalez-Pérez, Valerie M.; Guiblet, Wilfried; Heredia-Negrón, Aldo; Hernández-Muñiz, Jennifer; Irizarry-González, Lourdes N.; Laboy-Corales, Ángel L.; Llaurador-Caraballo, Gabriela A.; Marín-Maldonado, Frances; Marrero-Llerena, Ulises; Martell-Martínez, Héctor A.; Martínez-Traverso, Idaliz M.; Medina-Ortega, Kiara N.; Méndez-Castellanos, Sonya G.; Menéndez-Serrano, Krizia C.; Morales-Caraballo, Carol I.; Ortiz-DeChoudens, Saryleine; Ortiz-Ortiz, Patricia; Pagán-Torres, Hendrick; Pérez-Afanador, Diana; Quintana-Torres, Enid M.; Ramírez-Aponte, Edwin G.; Riascos-Cuero, Carolina; Rivera-Llovet, Michelle S.; Rivera-Pagán, Ingrid T.; Rivera-Vicéns, Ramón E.; Robles-Juarbe, Fabiola; Rodríguez-Bonilla, Lorraine; Rodríguez-Echevarría, Brian O.; Rodríguez-García, Priscila M.; Rodríguez-Laboy, Abneris E.; Rodríguez-Santiago, Susana; Rojas-Vargas, Michael L.; Rubio-Marrero, Eva N.; Santiago-Colón, Albeliz; Santiago-Ortiz, Jorge L.; Santos-Ramos, Carlos E.; Serrano-González, Joseline; Tamayo-Figueroa, Alina M.; Tascón-Peñaranda, Edna P.; Torres-Castillo, José L.; Valentín-Feliciano, Nelson A.; Valentín-Feliciano, Yashira M.; Vargas-Barreto, Nadyan M.; Vélez-Vázquez, Miguel; Vilanova-Vélez, Luis R.; Zambrana-Echevarría, Cristina; MacKinnon, Christy; Chung, Hui-Min; Kay, Chris; Pinto, Anthony; Kopp, Olga R.; Burkhardt, Joshua; Harward, Chris; Allen, Robert; Bhat, Pavan; Chang, Jimmy Hsiang-Chun; Chen, York; Chesley, Christopher; Cohn, Dara; DuPuis, David; Fasano, Michael; Fazzio, Nicholas; Gavinski, Katherine; Gebreyesus, Heran; Giarla, Thomas; Gostelow, Marcus; Greenstein, Rachel; Gunasinghe, Hashini; Hanson, Casey; Hay, Amanda; He, Tao Jian; Homa, Katie; Howe, Ruth; Howenstein, Jeff; Huang, Henry; Khatri, Aaditya; Kim, Young Lu; Knowles, Olivia; Kong, Sarah; Krock, Rebecca; Kroll, Matt; Kuhn, Julia; Kwong, Matthew; Lee, Brandon; Lee, Ryan; Levine, Kevin; Li, Yedda; Liu, Bo; Liu, Lucy; Liu, Max; Lousararian, Adam; Ma, Jimmy; Mallya, Allyson; Manchee, Charlie; Marcus, Joseph; McDaniel, Stephen; Miller, Michelle L.; Molleston, Jerome M.; Diez, Cristina Montero; Ng, Patrick; Ngai, Natalie; Nguyen, Hien; Nylander, Andrew; Pollack, Jason; Rastogi, Suchita; Reddy, Himabindu; Regenold, Nathaniel; Sarezky, Jon; Schultz, Michael; Shim, Jien; Skorupa, Tara; Smith, Kenneth; Spencer, Sarah J.; Srikanth, Priya; Stancu, Gabriel; Stein, Andrew P.; Strother, Marshall; Sudmeier, Lisa; Sun, Mengyang; Sundaram, Varun; Tazudeen, Noor; Tseng, Alan; Tzeng, Albert; Venkat, Rohit; Venkataram, Sandeep; Waldman, Leah; Wang, Tracy; Yang, Hao; Yu, Jack Y.; Zheng, Yin; Preuss, Mary L.; Garcia, Angelica; Juergens, Matt; Morris, Robert W.; Nagengast, Alexis A.; Azarewicz, Julie; Carr, Thomas J.; Chichearo, Nicole; Colgan, Mike; Donegan, Megan; Gardner, Bob; Kolba, Nik; Krumm, Janice L.; Lytle, Stacey; MacMillian, Laurell; Miller, Mary; Montgomery, Andrew; Moretti, Alysha; Offenbacker, Brittney; Polen, Mike; Toth, John; Woytanowski, John; Kadlec, Lisa; Crawford, Justin; Spratt, Mary L.; Adams, Ashley L.; Barnard, Brianna K.; Cheramie, Martin N.; Eime, Anne M.; Golden, Kathryn L.; Hawkins, Allyson P.; Hill, Jessica E.; Kampmeier, Jessica A.; Kern, Cody D.; Magnuson, Emily E.; Miller, Ashley R.; Morrow, Cody M.; Peairs, Julia C.; Pickett, Gentry L.; Popelka, Sarah A.; Scott, Alexis J.; Teepe, Emily J.; TerMeer, Katie A.; Watchinski, Carmen A.; Watson, Lucas A.; Weber, Rachel E.; Woodard, Kate A.; Barnard, Daron C.; Appiah, Isaac; Giddens, Michelle M.; McNeil, Gerard P.; Adebayo, Adeola; Bagaeva, Kate; Chinwong, Justina; Dol, Chrystel; George, Eunice; Haltaufderhyde, Kirk; Haye, Joanna; Kaur, Manpreet; Semon, Max; Serjanov, Dmitri; Toorie, Anika; Wilson, Christopher; Riddle, Nicole C.; Buhler, Jeremy; Mardis, Elaine R.
2015-01-01
The Muller F element (4.2 Mb, ~80 protein-coding genes) is an unusual autosome of Drosophila melanogaster; it is mostly heterochromatic with a low recombination rate. To investigate how these properties impact the evolution of repeats and genes, we manually improved the sequence and annotated the genes on the D. erecta, D. mojavensis, and D. grimshawi F elements and euchromatic domains from the Muller D element. We find that F elements have greater transposon density (25–50%) than euchromatic reference regions (3–11%). Among the F elements, D. grimshawi has the lowest transposon density (particularly DINE-1: 2% vs. 11–27%). F element genes have larger coding spans, more coding exons, larger introns, and lower codon bias. Comparison of the Effective Number of Codons with the Codon Adaptation Index shows that, in contrast to the other species, codon bias in D. grimshawi F element genes can be attributed primarily to selection instead of mutational biases, suggesting that density and types of transposons affect the degree of local heterochromatin formation. F element genes have lower estimated DNA melting temperatures than D element genes, potentially facilitating transcription through heterochromatin. Most F element genes (~90%) have remained on that element, but the F element has smaller syntenic blocks than genome averages (3.4–3.6 vs. 8.4–8.8 genes per block), indicating greater rates of inversion despite lower rates of recombination. Overall, the F element has maintained characteristics that are distinct from other autosomes in the Drosophila lineage, illuminating the constraints imposed by a heterochromatic milieu. PMID:25740935
Leung, Wilson; Shaffer, Christopher D; Reed, Laura K; Smith, Sheryl T; Barshop, William; Dirkes, William; Dothager, Matthew; Lee, Paul; Wong, Jeannette; Xiong, David; Yuan, Han; Bedard, James E J; Machone, Joshua F; Patterson, Seantay D; Price, Amber L; Turner, Bryce A; Robic, Srebrenka; Luippold, Erin K; McCartha, Shannon R; Walji, Tezin A; Walker, Chelsea A; Saville, Kenneth; Abrams, Marita K; Armstrong, Andrew R; Armstrong, William; Bailey, Robert J; Barberi, Chelsea R; Beck, Lauren R; Blaker, Amanda L; Blunden, Christopher E; Brand, Jordan P; Brock, Ethan J; Brooks, Dana W; Brown, Marie; Butzler, Sarah C; Clark, Eric M; Clark, Nicole B; Collins, Ashley A; Cotteleer, Rebecca J; Cullimore, Peterson R; Dawson, Seth G; Docking, Carter T; Dorsett, Sasha L; Dougherty, Grace A; Downey, Kaitlyn A; Drake, Andrew P; Earl, Erica K; Floyd, Trevor G; Forsyth, Joshua D; Foust, Jonathan D; Franchi, Spencer L; Geary, James F; Hanson, Cynthia K; Harding, Taylor S; Harris, Cameron B; Heckman, Jonathan M; Holderness, Heather L; Howey, Nicole A; Jacobs, Dontae A; Jewell, Elizabeth S; Kaisler, Maria; Karaska, Elizabeth A; Kehoe, James L; Koaches, Hannah C; Koehler, Jessica; Koenig, Dana; Kujawski, Alexander J; Kus, Jordan E; Lammers, Jennifer A; Leads, Rachel R; Leatherman, Emily C; Lippert, Rachel N; Messenger, Gregory S; Morrow, Adam T; Newcomb, Victoria; Plasman, Haley J; Potocny, Stephanie J; Powers, Michelle K; Reem, Rachel M; Rennhack, Jonathan P; Reynolds, Katherine R; Reynolds, Lyndsey A; Rhee, Dong K; Rivard, Allyson B; Ronk, Adam J; Rooney, Meghan B; Rubin, Lainey S; Salbert, Luke R; Saluja, Rasleen K; Schauder, Taylor; Schneiter, Allison R; Schulz, Robert W; Smith, Karl E; Spencer, Sarah; Swanson, Bryant R; Tache, Melissa A; Tewilliager, Ashley A; Tilot, Amanda K; VanEck, Eve; Villerot, Matthew M; Vylonis, Megan B; Watson, David T; Wurzler, Juliana A; Wysocki, Lauren M; Yalamanchili, Monica; Zaborowicz, Matthew A; Emerson, Julia A; Ortiz, Carlos; Deuschle, Frederic J; DiLorenzo, Lauren A; Goeller, Katie L; Macchi, Christopher R; Muller, Sarah E; Pasierb, Brittany D; Sable, Joseph E; Tucci, Jessica M; Tynon, Marykathryn; Dunbar, David A; Beken, Levent H; Conturso, Alaina C; Danner, Benjamin L; DeMichele, Gabriella A; Gonzales, Justin A; Hammond, Maureen S; Kelley, Colleen V; Kelly, Elisabeth A; Kulich, Danielle; Mageeney, Catherine M; McCabe, Nikie L; Newman, Alyssa M; Spaeder, Lindsay A; Tumminello, Richard A; Revie, Dennis; Benson, Jonathon M; Cristostomo, Michael C; DaSilva, Paolo A; Harker, Katherine S; Jarrell, Jenifer N; Jimenez, Luis A; Katz, Brandon M; Kennedy, William R; Kolibas, Kimberly S; LeBlanc, Mark T; Nguyen, Trung T; Nicolas, Daniel S; Patao, Melissa D; Patao, Shane M; Rupley, Bryan J; Sessions, Bridget J; Weaver, Jennifer A; Goodman, Anya L; Alvendia, Erica L; Baldassari, Shana M; Brown, Ashley S; Chase, Ian O; Chen, Maida; Chiang, Scott; Cromwell, Avery B; Custer, Ashley F; DiTommaso, Tia M; El-Adaimi, Jad; Goscinski, Nora C; Grove, Ryan A; Gutierrez, Nestor; Harnoto, Raechel S; Hedeen, Heather; Hong, Emily L; Hopkins, Barbara L; Huerta, Vilma F; Khoshabian, Colin; LaForge, Kristin M; Lee, Cassidy T; Lewis, Benjamin M; Lydon, Anniken M; Maniaci, Brian J; Mitchell, Ryan D; Morlock, Elaine V; Morris, William M; Naik, Priyanka; Olson, Nicole C; Osterloh, Jeannette M; Perez, Marcos A; Presley, Jonathan D; Randazzo, Matt J; Regan, Melanie K; Rossi, Franca G; Smith, Melanie A; Soliterman, Eugenia A; Sparks, Ciani J; Tran, Danny L; Wan, Tiffany; Welker, Anne A; Wong, Jeremy N; Sreenivasan, Aparna; Youngblom, Jim; Adams, Andrew; Alldredge, Justin; Bryant, Ashley; Carranza, David; Cifelli, Alyssa; Coulson, Kevin; Debow, Calise; Delacruz, Noelle; Emerson, Charlene; Farrar, Cassandra; Foret, Don; Garibay, Edgar; Gooch, John; Heslop, Michelle; Kaur, Sukhjit; Khan, Ambreen; Kim, Van; Lamb, Travis; Lindbeck, Peter; Lucas, Gabi; Macias, Elizabeth; Martiniuc, Daniela; Mayorga, Lissett; Medina, Joseph; Membreno, Nelson; Messiah, Shady; Neufeld, Lacey; Nguyen, San Francisco; Nichols, Zachary; Odisho, George; Peterson, Daymon; Rodela, Laura; Rodriguez, Priscilla; Rodriguez, Vanessa; Ruiz, Jorge; Sherrill, Will; Silva, Valeria; Sparks, Jeri; Statton, Geeta; Townsend, Ashley; Valdez, Isabel; Waters, Mary; Westphal, Kyle; Winkler, Stacey; Zumkehr, Joannee; DeJong, Randall J; Hoogewerf, Arlene J; Ackerman, Cheri M; Armistead, Isaac O; Baatenburg, Lara; Borr, Matthew J; Brouwer, Lindsay K; Burkhart, Brandon J; Bushhouse, Kelsey T; Cesko, Lejla; Choi, Tiffany Y Y; Cohen, Heather; Damsteegt, Amanda M; Darusz, Jess M; Dauphin, Cory M; Davis, Yelena P; Diekema, Emily J; Drewry, Melissa; Eisen, Michelle E M; Faber, Hayley M; Faber, Katherine J; Feenstra, Elizabeth; Felzer-Kim, Isabella T; Hammond, Brandy L; Hendriksma, Jesse; Herrold, Milton R; Hilbrands, Julia A; Howell, Emily J; Jelgerhuis, Sarah A; Jelsema, Timothy R; Johnson, Benjamin K; Jones, Kelly K; Kim, Anna; Kooienga, Ross D; Menyes, Erika E; Nollet, Eric A; Plescher, Brittany E; Rios, Lindsay; Rose, Jenny L; Schepers, Allison J; Scott, Geoff; Smith, Joshua R; Sterling, Allison M; Tenney, Jenna C; Uitvlugt, Chris; VanDyken, Rachel E; VanderVennen, Marielle; Vue, Samantha; Kokan, Nighat P; Agbley, Kwabea; Boham, Sampson K; Broomfield, Daniel; Chapman, Kayla; Dobbe, Ali; Dobbe, Ian; Harrington, William; Ibrahem, Marwan; Kennedy, Andre; Koplinsky, Chad A; Kubricky, Cassandra; Ladzekpo, Danielle; Pattison, Claire; Ramirez, Roman E; Wande, Lucia; Woehlke, Sarah; Wawersik, Matthew; Kiernan, Elizabeth; Thompson, Jeffrey S; Banker, Roxanne; Bartling, Justina R; Bhatiya, Chinmoy I; Boudoures, Anna L; Christiansen, Lena; Fosselman, Daniel S; French, Kristin M; Gill, Ishwar S; Havill, Jessen T; Johnson, Jaelyn L; Keny, Lauren J; Kerber, John M; Klett, Bethany M; Kufel, Christina N; May, Francis J; Mecoli, Jonathan P; Merry, Callie R; Meyer, Lauren R; Miller, Emily G; Mullen, Gregory J; Palozola, Katherine C; Pfeil, Jacob J; Thomas, Jessica G; Verbofsky, Evan M; Spana, Eric P; Agarwalla, Anant; Chapman, Julia; Chlebina, Ben; Chong, Insun; Falk, I N; Fitzgibbons, John D; Friedman, Harrison; Ighile, Osagie; Kim, Andrew J; Knouse, Kristin A; Kung, Faith; Mammo, Danny; Ng, Chun Leung; Nikam, Vinayak S; Norton, Diana; Pham, Philip; Polk, Jessica W; Prasad, Shreya; Rankin, Helen; Ratliff, Camille D; Scala, Victoria; Schwartz, Nicholas U; Shuen, Jessica A; Xu, Amy; Xu, Thomas Q; Zhang, Yi; Rosenwald, Anne G; Burg, Martin G; Adams, Stephanie J; Baker, Morgan; Botsford, Bobbi; Brinkley, Briana; Brown, Carter; Emiah, Shadie; Enoch, Erica; Gier, Chad; Greenwell, Alyson; Hoogenboom, Lindsay; Matthews, Jordan E; McDonald, Mitchell; Mercer, Amanda; Monsma, Nicholaus; Ostby, Kristine; Ramic, Alen; Shallman, Devon; Simon, Matthew; Spencer, Eric; Tomkins, Trisha; Wendland, Pete; Wylie, Anna; Wolyniak, Michael J; Robertson, Gregory M; Smith, Samuel I; DiAngelo, Justin R; Sassu, Eric D; Bhalla, Satish C; Sharif, Karim A; Choeying, Tenzin; Macias, Jason S; Sanusi, Fareed; Torchon, Karvyn; Bednarski, April E; Alvarez, Consuelo J; Davis, Kristen C; Dunham, Carrie A; Grantham, Alaina J; Hare, Amber N; Schottler, Jennifer; Scott, Zackary W; Kuleck, Gary A; Yu, Nicole S; Kaehler, Marian M; Jipp, Jacob; Overvoorde, Paul J; Shoop, Elizabeth; Cyrankowski, Olivia; Hoover, Betsy; Kusner, Matt; Lin, Devry; Martinov, Tijana; Misch, Jonathan; Salzman, Garrett; Schiedermayer, Holly; Snavely, Michael; Zarrasola, Stephanie; Parrish, Susan; Baker, Atlee; Beckett, Alissa; Belella, Carissa; Bryant, Julie; Conrad, Turner; Fearnow, Adam; Gomez, Carolina; Herbstsomer, Robert A; Hirsch, Sarah; Johnson, Christen; Jones, Melissa; Kabaso, Rita; Lemmon, Eric; Vieira, Carolina Marques Dos Santos; McFarland, Darryl; McLaughlin, Christopher; Morgan, Abbie; Musokotwane, Sepo; Neutzling, William; Nietmann, Jana; Paluskievicz, Christina; Penn, Jessica; Peoples, Emily; Pozmanter, Caitlin; Reed, Emily; Rigby, Nichole; Schmidt, Lasse; Shelton, Micah; Shuford, Rebecca; Tirasawasdichai, Tiara; Undem, Blair; Urick, Damian; Vondy, Kayla; Yarrington, Bryan; Eckdahl, Todd T; Poet, Jeffrey L; Allen, Alica B; Anderson, John E; Barnett, Jason M; Baumgardner, Jordan S; Brown, Adam D; Carney, Jordan E; Chavez, Ramiro A; Christgen, Shelbi L; Christie, Jordan S; Clary, Andrea N; Conn, Michel A; Cooper, Kristen M; Crowley, Matt J; Crowley, Samuel T; Doty, Jennifer S; Dow, Brian A; Edwards, Curtis R; Elder, Darcie D; Fanning, John P; Janssen, Bridget M; Lambright, Anthony K; Lane, Curtiss E; Limle, Austin B; Mazur, Tammy; McCracken, Marly R; McDonough, Alexa M; Melton, Amy D; Minnick, Phillip J; Musick, Adam E; Newhart, William H; Noynaert, Joseph W; Ogden, Bradley J; Sandusky, Michael W; Schmuecker, Samantha M; Shipman, Anna L; Smith, Anna L; Thomsen, Kristen M; Unzicker, Matthew R; Vernon, William B; Winn, Wesley W; Woyski, Dustin S; Zhu, Xiao; Du, Chunguang; Ament, Caitlin; Aso, Soham; Bisogno, Laura Simone; Caronna, Jason; Fefelova, Nadezhda; Lopez, Lenin; Malkowitz, Lorraine; Marra, Jonathan; Menillo, Daniella; Obiorah, Ifeanyi; Onsarigo, Eric Nyabeta; Primus, Shekerah; Soos, Mahdi; Tare, Archana; Zidan, Ameer; Jones, Christopher J; Aronhalt, Todd; Bellush, James M; Burke, Christa; DeFazio, Steve; Does, Benjamin R; Johnson, Todd D; Keysock, Nicholas; Knudsen, Nelson H; Messler, James; Myirski, Kevin; Rekai, Jade Lea; Rempe, Ryan Michael; Salgado, Michael S; Stagaard, Erica; Starcher, Justin R; Waggoner, Andrew W; Yemelyanova, Anastasia K; Hark, Amy T; Bertolet, Anne; Kuschner, Cyrus E; Parry, Kesley; Quach, Michael; Shantzer, Lindsey; Shaw, Mary E; Smith, Mary A; Glenn, Omolara; Mason, Portia; Williams, Charlotte; Key, S Catherine Silver; Henry, Tyneshia C P; Johnson, Ashlee G; White, Jackie X; Haberman, Adam; Asinof, Sam; Drumm, Kelly; Freeburg, Trip; Safa, Nadia; Schultz, Darrin; Shevin, Yakov; Svoronos, Petros; Vuong, Tam; Wellinghoff, Jules; Hoopes, Laura L M; Chau, Kim M; Ward, Alyssa; Regisford, E Gloria C; Augustine, LaJerald; Davis-Reyes, Brionna; Echendu, Vivienne; Hales, Jasmine; Ibarra, Sharon; Johnson, Lauriaun; Ovu, Steven; Braverman, John M; Bahr, Thomas J; Caesar, Nicole M; Campana, Christopher; Cassidy, Daniel W; Cognetti, Peter A; English, Johnathan D; Fadus, Matthew C; Fick, Cameron N; Freda, Philip J; Hennessy, Bryan M; Hockenberger, Kelsey; Jones, Jennifer K; King, Jessica E; Knob, Christopher R; Kraftmann, Karen J; Li, Linghui; Lupey, Lena N; Minniti, Carl J; Minton, Thomas F; Moran, Joseph V; Mudumbi, Krishna; Nordman, Elizabeth C; Puetz, William J; Robinson, Lauren M; Rose, Thomas J; Sweeney, Edward P; Timko, Ashley S; Paetkau, Don W; Eisler, Heather L; Aldrup, Megan E; Bodenberg, Jessica M; Cole, Mara G; Deranek, Kelly M; DeShetler, Megan; Dowd, Rose M; Eckardt, Alexandra K; Ehret, Sharon C; Fese, Jessica; Garrett, Amanda D; Kammrath, Anna; Kappes, Michelle L; Light, Morgan R; Meier, Anne C; O'Rouke, Allison; Perella, Mallory; Ramsey, Kimberley; Ramthun, Jennifer R; Reilly, Mary T; Robinett, Deirdre; Rossi, Nadine L; Schueler, Mary Grace; Shoemaker, Emma; Starkey, Kristin M; Vetor, Ashley; Vrable, Abby; Chandrasekaran, Vidya; Beck, Christopher; Hatfield, Kristen R; Herrick, Douglas A; Khoury, Christopher B; Lea, Charlotte; Louie, Christopher A; Lowell, Shannon M; Reynolds, Thomas J; Schibler, Jeanine; Scoma, Alexandra H; Smith-Gee, Maxwell T; Tuberty, Sarah; Smith, Christopher D; Lopilato, Jane E; Hauke, Jeanette; Roecklein-Canfield, Jennifer A; Corrielus, Maureen; Gilman, Hannah; Intriago, Stephanie; Maffa, Amanda; Rauf, Sabya A; Thistle, Katrina; Trieu, Melissa; Winters, Jenifer; Yang, Bib; Hauser, Charles R; Abusheikh, Tariq; Ashrawi, Yara; Benitez, Pedro; Boudreaux, Lauren R; Bourland, Megan; Chavez, Miranda; Cruz, Samantha; Elliott, GiNell; Farek, Jesse R; Flohr, Sarah; Flores, Amanda H; Friedrichs, Chelsey; Fusco, Zach; Goodwin, Zane; Helmreich, Eric; Kiley, John; Knepper, John Mark; Langner, Christine; Martinez, Megan; Mendoza, Carlos; Naik, Monal; Ochoa, Andrea; Ragland, Nicolas; Raimey, England; Rathore, Sunil; Reza, Evangelina; Sadovsky, Griffin; Seydoux, Marie-Isabelle B; Smith, Jonathan E; Unruh, Anna K; Velasquez, Vicente; Wolski, Matthew W; Gosser, Yuying; Govind, Shubha; Clarke-Medley, Nicole; Guadron, Leslie; Lau, Dawn; Lu, Alvin; Mazzeo, Cheryl; Meghdari, Mariam; Ng, Simon; Pamnani, Brad; Plante, Olivia; Shum, Yuki Kwan Wa; Song, Roy; Johnson, Diana E; Abdelnabi, Mai; Archambault, Alexi; Chamma, Norma; Gaur, Shailly; Hammett, Deborah; Kandahari, Adrese; Khayrullina, Guzal; Kumar, Sonali; Lawrence, Samantha; Madden, Nigel; Mandelbaum, Max; Milnthorp, Heather; Mohini, Shiv; Patel, Roshni; Peacock, Sarah J; Perling, Emily; Quintana, Amber; Rahimi, Michael; Ramirez, Kristen; Singhal, Rishi; Weeks, Corinne; Wong, Tiffany; Gillis, Aubree T; Moore, Zachary D; Savell, Christopher D; Watson, Reece; Mel, Stephanie F; Anilkumar, Arjun A; Bilinski, Paul; Castillo, Rostislav; Closser, Michael; Cruz, Nathalia M; Dai, Tiffany; Garbagnati, Giancarlo F; Horton, Lanor S; Kim, Dongyeon; Lau, Joyce H; Liu, James Z; Mach, Sandy D; Phan, Thu A; Ren, Yi; Stapleton, Kenneth E; Strelitz, Jean M; Sunjed, Ray; Stamm, Joyce; Anderson, Morgan C; Bonifield, Bethany Grace; Coomes, Daniel; Dillman, Adam; Durchholz, Elaine J; Fafara-Thompson, Antoinette E; Gross, Meleah J; Gygi, Amber M; Jackson, Lesley E; Johnson, Amy; Kocsisova, Zuzana; Manghelli, Joshua L; McNeil, Kylie; Murillo, Michael; Naylor, Kierstin L; Neely, Jessica; Ogawa, Emmy E; Rich, Ashley; Rogers, Anna; Spencer, J Devin; Stemler, Kristina M; Throm, Allison A; Van Camp, Matt; Weihbrecht, Katie; Wiles, T Aaron; Williams, Mallory A; Williams, Matthew; Zoll, Kyle; Bailey, Cheryl; Zhou, Leming; Balthaser, Darla M; Bashiri, Azita; Bower, Mindy E; Florian, Kayla A; Ghavam, Nazanin; Greiner-Sosanko, Elizabeth S; Karim, Helmet; Mullen, Victor W; Pelchen, Carly E; Yenerall, Paul M; Zhang, Jiayu; Rubin, Michael R; Arias-Mejias, Suzette M; Bermudez-Capo, Armando G; Bernal-Vega, Gabriela V; Colon-Vazquez, Mariela; Flores-Vazquez, Arelys; Gines-Rosario, Mariela; Llavona-Cartagena, Ivan G; Martinez-Rodriguez, Javier O; Ortiz-Fuentes, Lionel; Perez-Colomba, Eliezer O; Perez-Otero, Joseph; Rivera, Elisandra; Rodriguez-Giron, Luke J; Santiago-Sanabria, Arnaldo J; Senquiz-Gonzalez, Andrea M; delValle, Frank R Soto; Vargas-Franco, Dorianmarie; Velázquez-Soto, Karla I; Zambrana-Burgos, Joan D; Martinez-Cruzado, Juan Carlos; Asencio-Zayas, Lillyann; Babilonia-Figueroa, Kevin; Beauchamp-Pérez, Francis D; Belén-Rodríguez, Juliana; Bracero-Quiñones, Luciann; Burgos-Bula, Andrea P; Collado-Méndez, Xavier A; Colón-Cruz, Luis R; Correa-Muller, Ana I; Crooke-Rosado, Jonathan L; Cruz-García, José M; Defendini-Ávila, Marianna; Delgado-Peraza, Francheska M; Feliciano-Cancela, Alex J; Gónzalez-Pérez, Valerie M; Guiblet, Wilfried; Heredia-Negrón, Aldo; Hernández-Muñiz, Jennifer; Irizarry-González, Lourdes N; Laboy-Corales, Ángel L; Llaurador-Caraballo, Gabriela A; Marín-Maldonado, Frances; Marrero-Llerena, Ulises; Martell-Martínez, Héctor A; Martínez-Traverso, Idaliz M; Medina-Ortega, Kiara N; Méndez-Castellanos, Sonya G; Menéndez-Serrano, Krizia C; Morales-Caraballo, Carol I; Ortiz-DeChoudens, Saryleine; Ortiz-Ortiz, Patricia; Pagán-Torres, Hendrick; Pérez-Afanador, Diana; Quintana-Torres, Enid M; Ramírez-Aponte, Edwin G; Riascos-Cuero, Carolina; Rivera-Llovet, Michelle S; Rivera-Pagán, Ingrid T; Rivera-Vicéns, Ramón E; Robles-Juarbe, Fabiola; Rodríguez-Bonilla, Lorraine; Rodríguez-Echevarría, Brian O; Rodríguez-García, Priscila M; Rodríguez-Laboy, Abneris E; Rodríguez-Santiago, Susana; Rojas-Vargas, Michael L; Rubio-Marrero, Eva N; Santiago-Colón, Albeliz; Santiago-Ortiz, Jorge L; Santos-Ramos, Carlos E; Serrano-González, Joseline; Tamayo-Figueroa, Alina M; Tascón-Peñaranda, Edna P; Torres-Castillo, José L; Valentín-Feliciano, Nelson A; Valentín-Feliciano, Yashira M; Vargas-Barreto, Nadyan M; Vélez-Vázquez, Miguel; Vilanova-Vélez, Luis R; Zambrana-Echevarría, Cristina; MacKinnon, Christy; Chung, Hui-Min; Kay, Chris; Pinto, Anthony; Kopp, Olga R; Burkhardt, Joshua; Harward, Chris; Allen, Robert; Bhat, Pavan; Chang, Jimmy Hsiang-Chun; Chen, York; Chesley, Christopher; Cohn, Dara; DuPuis, David; Fasano, Michael; Fazzio, Nicholas; Gavinski, Katherine; Gebreyesus, Heran; Giarla, Thomas; Gostelow, Marcus; Greenstein, Rachel; Gunasinghe, Hashini; Hanson, Casey; Hay, Amanda; He, Tao Jian; Homa, Katie; Howe, Ruth; Howenstein, Jeff; Huang, Henry; Khatri, Aaditya; Kim, Young Lu; Knowles, Olivia; Kong, Sarah; Krock, Rebecca; Kroll, Matt; Kuhn, Julia; Kwong, Matthew; Lee, Brandon; Lee, Ryan; Levine, Kevin; Li, Yedda; Liu, Bo; Liu, Lucy; Liu, Max; Lousararian, Adam; Ma, Jimmy; Mallya, Allyson; Manchee, Charlie; Marcus, Joseph; McDaniel, Stephen; Miller, Michelle L; Molleston, Jerome M; Diez, Cristina Montero; Ng, Patrick; Ngai, Natalie; Nguyen, Hien; Nylander, Andrew; Pollack, Jason; Rastogi, Suchita; Reddy, Himabindu; Regenold, Nathaniel; Sarezky, Jon; Schultz, Michael; Shim, Jien; Skorupa, Tara; Smith, Kenneth; Spencer, Sarah J; Srikanth, Priya; Stancu, Gabriel; Stein, Andrew P; Strother, Marshall; Sudmeier, Lisa; Sun, Mengyang; Sundaram, Varun; Tazudeen, Noor; Tseng, Alan; Tzeng, Albert; Venkat, Rohit; Venkataram, Sandeep; Waldman, Leah; Wang, Tracy; Yang, Hao; Yu, Jack Y; Zheng, Yin; Preuss, Mary L; Garcia, Angelica; Juergens, Matt; Morris, Robert W; Nagengast, Alexis A; Azarewicz, Julie; Carr, Thomas J; Chichearo, Nicole; Colgan, Mike; Donegan, Megan; Gardner, Bob; Kolba, Nik; Krumm, Janice L; Lytle, Stacey; MacMillian, Laurell; Miller, Mary; Montgomery, Andrew; Moretti, Alysha; Offenbacker, Brittney; Polen, Mike; Toth, John; Woytanowski, John; Kadlec, Lisa; Crawford, Justin; Spratt, Mary L; Adams, Ashley L; Barnard, Brianna K; Cheramie, Martin N; Eime, Anne M; Golden, Kathryn L; Hawkins, Allyson P; Hill, Jessica E; Kampmeier, Jessica A; Kern, Cody D; Magnuson, Emily E; Miller, Ashley R; Morrow, Cody M; Peairs, Julia C; Pickett, Gentry L; Popelka, Sarah A; Scott, Alexis J; Teepe, Emily J; TerMeer, Katie A; Watchinski, Carmen A; Watson, Lucas A; Weber, Rachel E; Woodard, Kate A; Barnard, Daron C; Appiah, Isaac; 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2015-03-04
The Muller F element (4.2 Mb, ~80 protein-coding genes) is an unusual autosome of Drosophila melanogaster; it is mostly heterochromatic with a low recombination rate. To investigate how these properties impact the evolution of repeats and genes, we manually improved the sequence and annotated the genes on the D. erecta, D. mojavensis, and D. grimshawi F elements and euchromatic domains from the Muller D element. We find that F elements have greater transposon density (25-50%) than euchromatic reference regions (3-11%). Among the F elements, D. grimshawi has the lowest transposon density (particularly DINE-1: 2% vs. 11-27%). F element genes have larger coding spans, more coding exons, larger introns, and lower codon bias. Comparison of the Effective Number of Codons with the Codon Adaptation Index shows that, in contrast to the other species, codon bias in D. grimshawi F element genes can be attributed primarily to selection instead of mutational biases, suggesting that density and types of transposons affect the degree of local heterochromatin formation. F element genes have lower estimated DNA melting temperatures than D element genes, potentially facilitating transcription through heterochromatin. Most F element genes (~90%) have remained on that element, but the F element has smaller syntenic blocks than genome averages (3.4-3.6 vs. 8.4-8.8 genes per block), indicating greater rates of inversion despite lower rates of recombination. Overall, the F element has maintained characteristics that are distinct from other autosomes in the Drosophila lineage, illuminating the constraints imposed by a heterochromatic milieu. Copyright © 2015 Leung et al.
hp Spectral element methods for three dimensional elliptic problems
elliptic boundary value problems on non-smooth domains in R3. For Dirichlet problems, ... of variable degree bounded by W. Let N denote the number of layers in the geomet- ric mesh ... We prove a stability theorem for mixed problems when the spectral element functions vanish ..... Applying Theorem 3.1,. ∫ r l. |Mu|2dx −.
Three-dimensional wake field analysis by boundary element method
Miyata, K.
1987-01-01
A computer code HERTPIA was developed for the calculation of electromagnetic wake fields excited by charged particles travelling through arbitrarily shaped accelerating cavities. This code solves transient wave problems for a Hertz vector. The numerical analysis is based on the boundary element method. This program is validated by comparing its results with analytical solutions in a pill-box cavity
Choi, S. N.; Kim, H. N.; Jang, K. S.; Kim, H. J.
2000-01-01
The purpose of this paper is to determine a two dimensional axisymmetric model through a comparative study between a three dimensional and an axisymmetric finite element analysis of the reactor coolant piping nozzle subject to internal pressure. The finite element analysis results show that the stress adopting the axisymmetric model with the radius of equivalent spherical vessel are well agree with that adopting the three dimensional model. The radii of equivalent spherical vessel are 3.5 times and 7.3 times of the radius of the reactor coolant piping for the safety injection nozzle and for the residual heat removal nozzle, respectively
Multisymplectic Structure-Preserving in Simple Finite Element Method in High Dimensional Case
BAI Yong-Qiang; LIU Zhen; PEI Ming; ZHENG Zhu-Jun
2003-01-01
In this paper, we study a finite element scheme of some semi-linear elliptic boundary value problems inhigh-dimensional space. With uniform mesh, we find that, the numerical scheme derived from finite element method cankeep a preserved multisymplectic structure.
Three-dimensional modeling with finite element codes
Druce, R.L.
1986-01-17
This paper describes work done to model magnetostatic field problems in three dimensions. Finite element codes, available at LLNL, and pre- and post-processors were used in the solution of the mathematical model, the output from which agreed well with the experimentally obtained data. The geometry used in this work was a cylinder with ports in the periphery and no current sources in the space modeled. 6 refs., 8 figs.
Three dimensional mathematical model of tooth for finite element analysis
Puškar Tatjana
2010-01-01
Full Text Available Introduction. The mathematical model of the abutment tooth is the starting point of the finite element analysis of stress and deformation of dental structures. The simplest and easiest way is to form a model according to the literature data of dimensions and morphological characteristics of teeth. Our method is based on forming 3D models using standard geometrical forms (objects in programmes for solid modeling. Objective. Forming the mathematical model of abutment of the second upper premolar for finite element analysis of stress and deformation of dental structures. Methods. The abutment tooth has a form of a complex geometric object. It is suitable for modeling in programs for solid modeling SolidWorks. After analyzing the literature data about the morphological characteristics of teeth, we started the modeling dividing the tooth (complex geometric body into simple geometric bodies (cylinder, cone, pyramid,.... Connecting simple geometric bodies together or substricting bodies from the basic body, we formed complex geometric body, tooth. The model is then transferred into Abaqus, a computational programme for finite element analysis. Transferring the data was done by standard file format for transferring 3D models ACIS SAT. Results. Using the programme for solid modeling SolidWorks, we developed three models of abutment of the second maxillary premolar: the model of the intact abutment, the model of the endodontically treated tooth with two remaining cavity walls and the model of the endodontically treated tooth with two remaining walls and inserted post. Conclusion Mathematical models of the abutment made according to the literature data are very similar with the real abutment and the simplifications are minimal. These models enable calculations of stress and deformation of the dental structures. The finite element analysis provides useful information in understanding biomechanical problems and gives guidance for clinical research.
Brittle Fracture Mechanics of Snow : In Situ Testing and Distinct Element Modeling
Faillettaz, J.; Daudon, D.; Louchet, F.
development. The experimental cam- paign carried out in the Alps during the 2000-2001 winter on homogeneous sintered snow with a density of 200 kg/m3 (typical of a snow slab) gave results of the same or- der of magnitude as Michot's. A numerical modeling of these toughness experiments was performed using a distinct element code, considering snow as a cohesive granu- lar material. Both crack propagation and rupture patterns are in close agreement with experiments. References: Kirchner, Michot, Suzuki 2000 Fracture thoughness of snow in tension 1 Philisophical Magazine A, vol 80,N5, p1265-1272. Louchet 2001,A transition in dry snow slab avalanche triggering modes, Annales de glaciologie, vol 32,Symphosium on Snow, Avalanches and Impact of the Frest Cover, Innsbruck,Austria,22-26 may 2000, p2285-289 2
Cognitive flexibility: A distinct element of performance impairment due to sleep deprivation.
Honn, K A; Hinson, J M; Whitney, P; Van Dongen, H P A
2018-03-14
their response. In phase 1 of the task, subjects were explicitly told which stimuli were assigned to the go and no go sets. In phases 2 and 3, new stimuli were used that were different from those used in phase 1. Subjects were not explicitly told the go/no go mappings and were instead required to use accuracy feedback to learn which stimuli were in the go and nogo sets. Phase 3 continued directly from phase 2 and retained the same stimuli as in phase 2, but there was an unannounced reversal of the stimulus-response mappings. Task results confirmed that sleep deprivation resulted in loss of cognitive flexibility through feedback blunting, and that this effect was not produced solely by (1) general performance impairment because of overwhelming sleep drive; (2) reduced working memory resources available to perform the task; (3) incomplete learning of stimulus-response mappings before the unannounced reversal; or (4) interference with stimulus identification through lapses in vigilant attention. Overall, the results suggest that sleep deprivation causes a fundamental problem with dynamic attentional control. This element of performance impairment due to sleep deprivation appears to be distinct from vigilant attention deficits, and represents a particularly significant challenge for fatigue risk management. Copyright © 2018. Published by Elsevier Ltd.
Yoon, Gil Ho; Joung, Young Soo; Kim, Yoon Young
2005-01-01
The topology design optimization of “three-dimensional geometrically-nonlinear” continuum structures is still a difficult problem not only because of its problem size but also the occurrence of unstable continuum finite elements during the design optimization. To overcome this difficulty, the ele......) stiffness matrix of continuum finite elements. Therefore, any finite element code, including commercial codes, can be readily used for the ECP implementation. The key ideas and characteristics of these methods will be presented in this paper....
One-Dimensional Finite Elements An Introduction to the FE Method
Öchsner, Andreas
2013-01-01
This textbook presents finite element methods using exclusively one-dimensional elements. The aim is to present the complex methodology in an easily understandable but mathematically correct fashion. The approach of one-dimensional elements enables the reader to focus on the understanding of the principles of basic and advanced mechanical problems. The reader easily understands the assumptions and limitations of mechanical modeling as well as the underlying physics without struggling with complex mathematics. But although the description is easy it remains scientifically correct. The approach using only one-dimensional elements covers not only standard problems but allows also for advanced topics like plasticity or the mechanics of composite materials. Many examples illustrate the concepts and problems at the end of every chapter help to familiarize with the topics.
ARE ELEMENTAL FINGERPRINTS OF FISH OTOLITHS DISTINCT AMONG GREAT LAKES COASTAL NURSERY AREAS?
Elemental composition of an otolith reflects a fish's rearing environment, so otolith geochemistry can record differences in ambient water conditions specific to habitats used during a fish's life history. Although few studies have been conducted in freshwater, trace ...
Grossnickle, Emily M.
2016-01-01
Curiosity has received increasing attention in the educational literature, yet empirical investigations have been limited by inconsistent conceptualizations and the use of curiosity synonymously with other constructs, particularly interest. The purpose of this review is to critically examine the dimensionality, definitions, and measures of…
Muto, K.; Motosaka, M.; Kamata, M.; Masuda, K.; Urao, K.; Mameda, T.
1985-01-01
In order to investigate the 3-dimensional earthquake response characteristics of an embedded structure with consideration for soil-structure interaction, the authors have developed an analytical method using 3-dimensional hybrid model of boundary elements (BEM) and finite elements (FEM) and have conducted a dynamic analysis of an actual nuclear reactor building. This paper describes a comparative study between two different embedment depths in soil as elastic half-space. As the results, it was found that the earthquake response intensity decreases with the increase of the embedment depth and that this method was confirmed to be effective for investigating the 3-D response characteristics of embedded structures such as deflection pattern of each floor level, floor response spectra in high frequency range. (orig.)
Simple one-dimensional finite element algorithm with multi-dimensional capabilities
Pepper, D.W.; Baker, A.J.
1978-01-01
The application of the finite element procedure for the solution of partial differential equations is gaining widespread acceptance. The ability of the finite element procedure to solve problems which are arbitrarily shaped as well as the alleviation of boundary condition problems is well known. By using local interpolation functionals over each subdomain, or element, a set of linearized algebraic equations are obtained which can be solved using any direct, iterative, or inverse numerical technique. Subsequent use of an explicit or implicit integration procedure permits closure of the solution over the global domain
Elliott Ferris
2018-03-01
Full Text Available The identity of most functional elements in the mammalian genome and the phenotypes they impact are unclear. Here, we perform a genome-wide comparative analysis of patterns of accelerated evolution in species with highly distinctive traits to discover candidate functional elements for clinically important phenotypes. We identify accelerated regions (ARs in the elephant, hibernating bat, orca, dolphin, naked mole rat, and thirteen-lined ground squirrel lineages in mammalian conserved regions, uncovering ∼33,000 elements that bind hundreds of different regulatory proteins in humans and mice. ARs in the elephant, the largest land mammal, are uniquely enriched near elephant DNA damage response genes. The genomic hotspot for elephant ARs is the E3 ligase subunit of the Fanconi anemia complex, a master regulator of DNA repair. Additionally, ARs in the six species are associated with specific human clinical phenotypes that have apparent concordance with overt traits in each species.
Mixed finite element simulations in two-dimensional groundwater flow problems
Kimura, Hideo
1989-01-01
A computer code of groundwater flow in two-dimensional porous media based on the mixed finite element method was developed for accurate approximations of Darcy velocities in safety evaluation of radioactive waste disposal. The mixed finite element procedure solves for both the Darcy velocities and pressure heads simultaneously in the Darcy equation and continuity equation. Numerical results of a single well pumping at a constant rate in a uniform flow field showed that the mixed finite element method gives more accurate Darcy velocities nearly 50 % on average error than standard finite element method. (author)
Calculation of two-dimensional thermal transients by the finite element method
Fontoura Rodrigues, J.L.A. da; Barcellos, C.S. de
1981-01-01
The linear heat conduction through anisotropic and/or heterogeneous matter, in either two-dimensional fields with any kind of geometry or three-dimensional fields with axial symmetry is analysed. It only accepts time-independent boundary conditions and it is possible to have internal heat generation. The solution is obtained by modal analysis employing the finite element method under Galerkin formulation. (Author) [pt
Ishiguro, Misako; Higuchi, Kenji
1983-01-01
The finite element method is applied in Galerkin-type approximation to three-dimensional neutron diffusion equations of fast reactors. A hexagonal element scheme is adopted for treating the hexagonal lattice which is typical for fast reactors. The validity of the scheme is verified by applying the scheme as well as alternative schemes to the neutron diffusion calculation of a gas-cooled fast reactor of actual scale. The computed results are compared with corresponding values obtained using the currently applied triangular-element and also with conventional finite difference schemes. The hexagonal finite element scheme is found to yield a reasonable solution to the problem taken up here, with some merit in terms of saving in computing time, but the resulting multiplication factor differs by 1% and the flux by 9% compared with the triangular mesh finite difference scheme. The finite element method, even in triangular element scheme, would appear to incur error in inadmissible amount and which could not be easily eliminated by refining the nodes. (author)
Song, Yeo-Ul; Youn, Sung-Kie; Park, K. C.
2017-10-01
A method for three-dimensional non-matching interface treatment with a virtual gap element is developed. When partitioned structures contain curved interfaces and have different brick meshes, the discretized models have gaps along the interfaces. As these gaps bring unexpected errors, special treatments are required to handle the gaps. In the present work, a virtual gap element is introduced to link the frame and surface domain nodes in the frame work of the mortar method. Since the surface of the hexahedron element is quadrilateral, the gap element is pyramidal. The pyramidal gap element consists of four domain nodes and one frame node. Zero-strain condition in the gap element is utilized for the interpolation of frame nodes in terms of the domain nodes. This approach is taken to satisfy the momentum and energy conservation. The present method is applicable not only to curved interfaces with gaps, but also to flat interfaces in three dimensions. Several numerical examples are given to describe the effectiveness and accuracy of the proposed method.
Non-Linear Three Dimensional Finite Elements for Composite Concrete Structures
O. Kohnehpooshi
Full Text Available Abstract The current investigation focused on the development of effective and suitable modelling of reinforced concrete component with and without strengthening. The modelling includes physical and constitutive models. New interface elements have been developed, while modified constitutive law have been applied and new computational algorithm is utilised. The new elements are the Truss-link element to model the interaction between concrete and reinforcement bars, the interface element between two plate bending elements and the interface element to represent the interfacial behaviour between FRP, steel plates and concrete. Nonlinear finite-element (FE codes were developed with pre-processing. The programme was written using FORTRAN language. The accuracy and efficiency of the finite element programme were achieved by analyzing several examples from the literature. The application of the 3D FE code was further enhanced by carrying out the numerical analysis of the three dimensional finite element analysis of FRP strengthened RC beams, as well as the 3D non-linear finite element analysis of girder bridge. Acceptable distributions of slip, deflection, stresses in the concrete and FRP plate have also been found. These results show that the new elements are effective and appropriate to be used for structural component modelling.
A finite element method for calculating the 3-dimensional magnetic fields of cyclotron
Zhao Xiaofeng
1986-01-01
A series of formula of the finite element method (scalar potential) for calculating the three-dimensional magnetic field of the main magnet of a sector focused cyclotron, and the realization method of the periodic boundary conditions in the code are given
Separate elements of episodic memory subserved by distinct hippocampal-prefrontal connections.
Barker, Gareth R I; Banks, Paul J; Scott, Hannah; Ralph, G Scott; Mitrophanous, Kyriacos A; Wong, Liang-Fong; Bashir, Zafar I; Uney, James B; Warburton, E Clea
2017-02-01
Episodic memory formation depends on information about a stimulus being integrated within a precise spatial and temporal context, a process dependent on the hippocampus and prefrontal cortex. Investigations of putative functional interactions between these regions are complicated by multiple direct and indirect hippocampal-prefrontal connections. Here application of a pharmacogenetic deactivation technique enabled us to investigate the mnemonic contributions of two direct hippocampal-medial prefrontal cortex (mPFC) pathways, one arising in the dorsal CA1 (dCA1) and the other in the intermediate CA1 (iCA1). While deactivation of either pathway impaired episodic memory, the resulting pattern of mnemonic deficits was different: deactivation of the dCA1→mPFC pathway selectively disrupted temporal order judgments while iCA1→mPFC pathway deactivation disrupted spatial memory. These findings reveal a previously unsuspected division of function among CA1 neurons that project directly to the mPFC. Such subnetworks may enable the distinctiveness of contextual information to be maintained in an episodic memory circuit.
Three-dimensional linear fracture mechanics analysis by a displacement-hybrid finite-element model
Atluri, S.N.; Kathiresan, K.; Kobayashi, A.S.
1975-01-01
This paper deals with a finite-element procedures for the calculation of modes I, II and III stress intensity factors, which vary, along an arbitrarily curved three-dimensional crack front in a structural component. The finite-element model is based on a modified variational principle of potential energy with relaxed continuity requirements for displacements at the inter-element boundary. The variational principle is a three-field principle, with the arbitrary interior displacements for the element, interelement boundary displacements, and element boundary tractions as variables. The unknowns in the final algebraic system of equations, in the present displacement hybrid finite element model, are the nodal displacements and the three elastic stress intensity factors. Special elements, which contain proper square root and inverse square root crack front variations in displacements and stresses, respectively, are used in a fixed region near the crack front. Interelement displacement compatibility is satisfied by assuming an independent interelement boundary displacement field, and using a Lagrange multiplier technique to enforce such interelement compatibility. These Lagrangean multipliers, which are physically the boundary tractions, are assumed from an equilibrated stress field derived from three-dimensional Beltrami (or Maxwell-Morera) stress functions that are complete. However, considerable care should be exercised in the use of these stress functions such that the stresses produced by any of these stress function components are not linearly dependent
Finite element method for radiation heat transfer in multi-dimensional graded index medium
Liu, L.H.; Zhang, L.; Tan, H.P.
2006-01-01
In graded index medium, ray goes along a curved path determined by Fermat principle, and curved ray-tracing is very difficult and complex. To avoid the complicated and time-consuming computation of curved ray trajectories, a finite element method based on discrete ordinate equation is developed to solve the radiative transfer problem in a multi-dimensional semitransparent graded index medium. Two particular test problems of radiative transfer are taken as examples to verify this finite element method. The predicted dimensionless net radiative heat fluxes are determined by the proposed method and compared with the results obtained by finite volume method. The results show that the finite element method presented in this paper has a good accuracy in solving the multi-dimensional radiative transfer problem in semitransparent graded index medium
Wang, Q; Yang, Y; Fei, Q; Li, D; Li, J J; Meng, H; Su, N; Fan, Z H; Wang, B Q
2017-06-06
Objective: To build a three-dimensional finite element models of a modified posterior cervical single open-door laminoplasty with short-segmental lateral mass screws fusion. Methods: The C(2)-C(7) segmental data were obtained from computed tomography (CT) scans of a male patient with cervical spondylotic myelopathy and spinal stenosis.Three-dimensional finite element models of a modified cervical single open-door laminoplasty (before and after surgery) were constructed by the combination of software package MIMICS, Geomagic and ABAQUS.The models were composed of bony vertebrae, articulating facets, intervertebral disc and associated ligaments.The loads of moments 1.5Nm at different directions (flexion, extension, lateral bending and axial rotation)were applied at preoperative model to calculate intersegmental ranges of motion.The results were compared with the previous studies to verify the validation of the models. Results: Three-dimensional finite element models of the modified cervical single open- door laminoplasty had 102258 elements (preoperative model) and 161 892 elements (postoperative model) respectively, including C(2-7) six bony vertebraes, C(2-3)-C(6-7) five intervertebral disc, main ligaments and lateral mass screws.The intersegmental responses at the preoperative model under the loads of moments 1.5 Nm at different directions were similar to the previous published data. Conclusion: Three-dimensional finite element models of the modified cervical single open- door laminoplasty were successfully established and had a good biological fidelity, which can be used for further study.
Ferris, Elliott; Abegglen, Lisa M; Schiffman, Joshua D; Gregg, Christopher
2018-03-06
The identity of most functional elements in the mammalian genome and the phenotypes they impact are unclear. Here, we perform a genome-wide comparative analysis of patterns of accelerated evolution in species with highly distinctive traits to discover candidate functional elements for clinically important phenotypes. We identify accelerated regions (ARs) in the elephant, hibernating bat, orca, dolphin, naked mole rat, and thirteen-lined ground squirrel lineages in mammalian conserved regions, uncovering ∼33,000 elements that bind hundreds of different regulatory proteins in humans and mice. ARs in the elephant, the largest land mammal, are uniquely enriched near elephant DNA damage response genes. The genomic hotspot for elephant ARs is the E3 ligase subunit of the Fanconi anemia complex, a master regulator of DNA repair. Additionally, ARs in the six species are associated with specific human clinical phenotypes that have apparent concordance with overt traits in each species. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.
Calculation of two-dimensional thermal transients by the method of finite elements
Fontoura Rodrigues, J.L.A. da.
1980-08-01
The unsteady linear heat conduction analysis throught anisotropic and/or heterogeneous matter, in either two-dimensional fields with any kind of geometry or three-dimensional fields with axial symmetry is presented. The boundary conditions and the internal heat generation are supposed time - independent. The solution is obtained by modal analysis employing the finite element method under Galerkin formulation. Optionally, it can be used with a reduced resolution method called Stoker Economizing Method wich allows a decrease on the program processing costs. (Author) [pt
A three-dimensional cell-based smoothed finite element method for elasto-plasticity
Lee, Kye Hyung; Im, Se Yong; Lim, Jae Hyuk; Sohn, Dong Woo
2015-01-01
This work is concerned with a three-dimensional cell-based smoothed finite element method for application to elastic-plastic analysis. The formulation of smoothed finite elements is extended to cover elastic-plastic deformations beyond the classical linear theory of elasticity, which has been the major application domain of smoothed finite elements. The finite strain deformations are treated with the aid of the formulation based on the hyperelastic constitutive equation. The volumetric locking originating from the nearly incompressible behavior of elastic-plastic deformations is remedied by relaxing the volumetric strain through the mean value. The comparison with the conventional finite elements demonstrates the effectiveness and accuracy of the present approach.
Numerical solution of multi group-Two dimensional- Adjoint equation with finite element method
Poursalehi, N.; Khalafi, H.; Shahriari, M.; Minoochehr
2008-01-01
Adjoint equation is used for perturbation theory in nuclear reactor design. For numerical solution of adjoint equation, usually two methods are applied. These are Finite Element and Finite Difference procedures. Usually Finite Element Procedure is chosen for solving of adjoint equation, because it is more use able in variety of geometries. In this article, Galerkin Finite Element method is discussed. This method is applied for numerical solving multi group, multi region and two dimensional (X, Y) adjoint equation. Typical reactor geometry is partitioned with triangular meshes and boundary condition for adjoint flux is considered zero. Finally, for a case of defined parameters, Finite Element Code was applied and results were compared with Citation Code
A three-dimensional cell-based smoothed finite element method for elasto-plasticity
Lee, Kye Hyung; Im, Se Yong [KAIST, Daejeon (Korea, Republic of); Lim, Jae Hyuk [KARI, Daejeon (Korea, Republic of); Sohn, Dong Woo [Korea Maritime and Ocean University, Busan (Korea, Republic of)
2015-02-15
This work is concerned with a three-dimensional cell-based smoothed finite element method for application to elastic-plastic analysis. The formulation of smoothed finite elements is extended to cover elastic-plastic deformations beyond the classical linear theory of elasticity, which has been the major application domain of smoothed finite elements. The finite strain deformations are treated with the aid of the formulation based on the hyperelastic constitutive equation. The volumetric locking originating from the nearly incompressible behavior of elastic-plastic deformations is remedied by relaxing the volumetric strain through the mean value. The comparison with the conventional finite elements demonstrates the effectiveness and accuracy of the present approach.
Trace elements, potassium, 40K and 137Cs in distinctive parts of fir from Gorski Kotar - Croatia
Barisic, D.; Vertacnik, A.; Lulic, S.; Kauzlaric, Z.; Hus, M.; Seletkovic, Z.; Kezic, N.
1996-01-01
Radionuclides, as well as other cations, which are either constitutive elements/trace elements of soils, or deposited as a fallout through wet/dry deposition processes due to global atmospheric contamination, can migrate upwards by plant uptake. Long-term observations of 137 Cs activities in nectar honeys indicate the uniform lowering of caesium transfer to nectar plants. In the same time, the 137 Cs activities of honey-dew honeys are significantly high and almost constant over long time period after contamination. Due to this, the research of potassium, caesium, as well as some other trace element content in distinctive parts of coniferous trees from Gorski Kotar has been started. The results of total K, Rb, Sr, Co, Cu, Zn and Cr, as well as of 40 K and 137 Cs determination in fir branches and needles from Lividraga (Table 1.) indicate the relatively high cations' mobility in youngest part of fir branches shoots. The majority of observed elements migrates into the youngest shoots, which is especially evident for univalent cations 40 K, total potassium, 137 Cs and rubidium in fir branches. Their concentrations generally are significantly higher in branches than in respective needles. The two-valent cations like strontium or zinc show less significant concentration increase in younger vs. older fir branches' parts (Figure 1.). Strontium concentrations have been increasing in the older needles in contrast to concentrations in fir branches. High 137 Cs activities found in the youngest shoots relatively long time after the soil contamination indicate the fir as a potentially good bioindicator for caesium. high mobility of cations in the youngest parts of fir branches, and theirs piling up in youngest tops of branches and needles suggest the fir to be used as the possible bioindicator of other, especially univalent cations fate. (author)
Midtgaard, Ole-Morten
1997-12-31
This thesis considers the feasibility of doing calculations to optimize electrical machines without the need to build expensive prototypes. It deals with the construction and assessment of new, hierarchical, hexahedral edge elements for three-dimensional computations of eddy currents with the electric vector potential formulation. The new elements, five in all, gave up to second-order approximations for both the magnetic field and the current density. Theoretical arguments showed these elements to be more economical for a given polynomial order of the approximated fields than the serendipity family of nodal elements. Further it was pointed out how the support of a source field computed by using edge elements could be made very small provided that a proper spanning tree was used in the edge element mesh. This was exploited for the voltage forcing technique, where source fields were used as basis functions, with unknown total currents in voltage forced conductors as degrees of freedom. The practical assessment of the edge elements proved the accuracy to improve with increasing polynomial order, both for local and global quantities. The most economical element was, however, one giving only complete first-order approximations for both fields. Further, the edge elements turned out to be better than the nodal elements also in practice. For the voltage forcing technique, source field basis functions which had small support, resulted in large reduction of the CPU-time for solving the main equation system, compared to source fields which had large support. The new elements can be used in a p-type adaptive scheme, and they should also be applicable for other tangentially continuous field problems. 67 refs., 34 figs., 10 tabs.
Simulation of three-dimensional, time-dependent, incompressible flows by a finite element method
Chan, S.T.; Gresho, P.M.; Lee, R.L.; Upson, C.D.
1981-01-01
A finite element model has been developed for simulating the dynamics of problems encountered in atmospheric pollution and safety assessment studies. The model is based on solving the set of three-dimensional, time-dependent, conservation equations governing incompressible flows. Spatial discretization is performed via a modified Galerkin finite element method, and time integration is carried out via the forward Euler method (pressure is computed implicitly, however). Several cost-effective techniques (including subcycling, mass lumping, and reduced Gauss-Legendre quadrature) which have been implemented are discussed. Numerical results are presented to demonstrate the applicability of the model
Satomi, Tomoaki; Konda, Naoki; Takahashi, Hiroshi
Fiber-cement-stabilized soil method is an effective way to recycle high-water content mud. The modified soil has several advantages such as high failure stress and high failure strain. However, the quality of the modified soil is not constant and depends on the water content of the mud and additives. Therefore, experimental verification to obtain the strength characteristics of the modified soil is necessary, but conducting experiments under various conditions is ineffective and uneconomic. In this study, a numerical model to estimate deformation-strength characteristics of the modified soil is investigated by using Distinct Element Method (DEM). It was shown that the developed model was effective way to estimate deformation-strength characteristics. Moreover, it was confirmed that the modified soil had high earthquake resistance.
Subsonic flow past three-dimensional localised heating elements in boundary layers
Aljohani, A F [Department of Mathematics, Faculty of Science, University of Tabuk (Saudi Arabia); Gajjar, J S B, E-mail: j.gajjar@manchester.ac.uk [School of Mathematics, University of Manchester, Manchester M13 9PL (United Kingdom)
2017-12-15
The problem of subsonic flow past three-dimensional micro-electro-mechanical-type (MEMS-type) heating elements placed on a flat surface, where the MEMS devices have hump-shaped surfaces, is investigated using the triple-deck theory. The compressible Navier–Stokes equations supplemented by the energy equation are considered in the limit when the Reynolds number is large. The dimensions of the MEMS devices considered are such that the flow perturbations are governed by the three-dimensional subsonic triple-deck equations formulated with the aid of method of matched expansions. The linear analysis of these equations is presented and our results provide an insight into how the MEMS heating elements may be used to positively control the local flow properties. (paper)
Two-dimensional finite element heat transfer model of softwood. Part II, Macrostructural effects
Hongmei Gu; John F. Hunt
2006-01-01
A two-dimensional finite element model was used to study the effects of structural features on transient heat transfer in softwood lumber with various orientations. Transient core temperature was modeled for lumber samples âcutâ from various locations within a simulated log. The effects of ring orientation, earlywood to latewood (E/L) ratio, and ring density were...
Development of three-dimensional transport code by the double finite element method
Fujimura, Toichiro
1985-01-01
Development of a three-dimensional neutron transport code by the double finite element method is described. Both of the Galerkin and variational methods are adopted to solve the problem, and then the characteristics of them are compared. Computational results of the collocation method, developed as a technique for the vaviational one, are illustrated in comparison with those of an Ssub(n) code. (author)
Two-dimensional finite element neutron diffusion analysis using hierarchic shape functions
Carpenter, D.C.
1997-01-01
Recent advances have been made in the use of p-type finite element method (FEM) for structural and fluid dynamics problems that hold promise for reactor physics problems. These advances include using hierarchic shape functions, element-by-element iterative solvers and more powerful mapping techniques. Use of the hierarchic shape functions allows greater flexibility and efficiency in implementing energy-dependent flux expansions and incorporating localized refinement of the solution space. The irregular matrices generated by the p-type FEM can be solved efficiently using element-by-element conjugate gradient iterative solvers. These solvers do not require storage of either the global or local stiffness matrices and can be highly vectorized. Mapping techniques based on blending function interpolation allow exact representation of curved boundaries using coarse element grids. These features were implemented in a developmental two-dimensional neutron diffusion program based on the use of hierarchic shape functions (FEM2DH). Several aspects in the effective use of p-type analysis were explored. Two choices of elemental preconditioning were examined--the proper selection of the polynomial shape functions and the proper number of functions to use. Of the five shape function polynomials tested, the integral Legendre functions were the most effective. The serendipity set of functions is preferable over the full tensor product set. Two global preconditioners were also examined--simple diagonal and incomplete Cholesky. The full effectiveness of the finite element methodology was demonstrated on a two-region, two-group cylindrical problem but solved in the x-y coordinate space, using a non-structured element grid. The exact, analytic eigenvalue solution was achieved with FEM2DH using various combinations of element grids and flux expansions
Lowenthal, D.H.; Wunschel, K.R.; Rahn, K.A.
1988-01-01
The two major requirements for a successful regional tracer system are distinctness of signatures and stability of signatures during transport. Dissimilarity of the five regional signatures from eastern North America is shown by collinearity diagnostics and by apportionment of synthetic samples generated randomly. Stability of regional signatures during transport is shown first by use of tracer elements in coarse and fine aerosol to predict the maximum possible change of ratios from particle-size effects alone and then by examination of actual changes in signatures during transport from the Midwest to Underhill, VT. Two recent empirical validations of the tracer system are presented: qualitative agreement of pulses of mid-western aerosol in Vermont with pulses of perfluorocarbon tracer gas released in Ohio during CAPTEX '83 and reproduction of our three major northeastern and mid-western signatures by other investigators. The tracer system currently uses the seven elements As, Se, Sb, Zn, In, noncrustal Mn, and noncrustal V as measured by instrumental neutron activation
Finite element method for one-dimensional rill erosion simulation on a curved slope
Lijuan Yan
2015-03-01
Full Text Available Rill erosion models are important to hillslope soil erosion prediction and to land use planning. The development of rill erosion models and their use has become increasingly of great concern. The purpose of this research was to develop mathematic models with computer simulation procedures to simulate and predict rill erosion. The finite element method is known as an efficient tool in many other applications than in rill soil erosion. In this study, the hydrodynamic and sediment continuity model equations for a rill erosion system were solved by the Galerkin finite element method and Visual C++ procedures. The simulated results are compared with the data for spatially and temporally measured processes for rill erosion under different conditions. The results indicate that the one-dimensional linear finite element method produced excellent predictions of rill erosion processes. Therefore, this study supplies a tool for further development of a dynamic soil erosion prediction model.
Kulak, R.F.; Belytschko, T.B.
1975-09-01
The formulation of a finite-element procedure for the implicit transient and static analysis of plate/shell type structures in three-dimensional space is described. The triangular plate/shell element can sustain both membrane and bending stresses. Both geometric and material nonlinearities can be treated, and an elastic-plastic material law has been incorporated. The formulation permits the element to undergo arbitrarily large rotations and translations; but, in its present form it is restricted to small strains. The discretized equations of motion are obtained by a stiffness method. An implicit integration algorithm based on trapezoidal integration formulas is used to integrate the discretized equations of motion in time. To ensure numerical stability, an iterative solution procedure with equilibrium checks is used
Application of finite-element method to three-dimensional nuclear reactor analysis
Cheung, K.Y.
1985-01-01
The application of the finite element method to solve a realistic one-or-two energy group, multiregion, three-dimensional static neutron diffusion problem is studied. Linear, quadratic, and cubic serendipity box-shape elements are used. The resulting sets of simultaneous algebraic equations with thousands of unknowns are solved by the conjugate gradient method, without forming the large coefficient matrix explicitly. This avoids the complicated data management schemes to store such a large coefficient matrix. Three finite-element computer programs: FEM-LINEAR, FEM-QUADRATIC and FEM-CUBIC were developed, using the linear, quadratic, and cubic box-shape elements respectively. They are self-contained, using simple nodal labeling schemes, without the need for separate finite element mesh generating routines. The efficiency and accuracy of these computer programs are then compared among themselves, and with other computer codes. The cubic element model is not recommended for practical usage because it gives almost identical results as the quadratic model, but it requires considerably longer computation time. The linear model is less accurate than the quadratic model, but it requires much shorter computation time. For a large 3-D problem, the linear model is to be preferred since it gives acceptable accuracy. The quadratic model may be used if improved accuracy is desired
Michael A Lodato
Full Text Available SOX2 is a master regulator of both pluripotent embryonic stem cells (ESCs and multipotent neural progenitor cells (NPCs; however, we currently lack a detailed understanding of how SOX2 controls these distinct stem cell populations. Here we show by genome-wide analysis that, while SOX2 bound to a distinct set of gene promoters in ESCs and NPCs, the majority of regions coincided with unique distal enhancer elements, important cis-acting regulators of tissue-specific gene expression programs. Notably, SOX2 bound the same consensus DNA motif in both cell types, suggesting that additional factors contribute to target specificity. We found that, similar to its association with OCT4 (Pou5f1 in ESCs, the related POU family member BRN2 (Pou3f2 co-occupied a large set of putative distal enhancers with SOX2 in NPCs. Forced expression of BRN2 in ESCs led to functional recruitment of SOX2 to a subset of NPC-specific targets and to precocious differentiation toward a neural-like state. Further analysis of the bound sequences revealed differences in the distances of SOX and POU peaks in the two cell types and identified motifs for additional transcription factors. Together, these data suggest that SOX2 controls a larger network of genes than previously anticipated through binding of distal enhancers and that transitions in POU partner factors may control tissue-specific transcriptional programs. Our findings have important implications for understanding lineage specification and somatic cell reprogramming, where SOX2, OCT4, and BRN2 have been shown to be key factors.
Park, Jai Hak
2009-01-01
SGBEM(Symmetric Galerkin Boundary Element Method)-FEM alternating method has been proposed by Nikishkov, Park and Atluri. In the proposed method, arbitrarily shaped three-dimensional crack problems can be solved by alternating between the crack solution in an infinite body and the finite element solution without a crack. In the previous study, the SGBEM-FEM alternating method was extended further in order to solve elastic-plastic crack problems and to obtain elastic-plastic stress fields. For the elastic-plastic analysis the algorithm developed by Nikishkov et al. is used after modification. In the algorithm, the initial stress method is used to obtain elastic-plastic stress and strain fields. In this paper, elastic-plastic J integrals for three-dimensional cracks are obtained using the method. For that purpose, accurate values of displacement gradients and stresses are necessary on an integration path. In order to improve the accuracy of stress near crack surfaces, coordinate transformation and partitioning of integration domain are used. The coordinate transformation produces a transformation Jacobian, which cancels the singularity of the integrand. Using the developed program, simple three-dimensional crack problems are solved and elastic and elastic-plastic J integrals are obtained. The obtained J integrals are compared with the values obtained using a handbook solution. It is noted that J integrals obtained from the alternating method are close to the values from the handbook
Three-dimensional finite element impact analysis of a nuclear waste truck cask
Miller, J.D.
1985-01-01
This paper presents a three-dimensional finite element impact analysis of a hypothetical accident event for the preliminary design of a shipping cask which is used to transport radioactive waste by standard tractor-semitrailer truck. The nonlinear dynamic structural analysis code DYNA3D run on Sandia's Cray-1 computer was used to calculate the effects of the cask's closure-end impacting a rigid frictionless surface on an edge of its external impact limiter after a 30-foot fall. The center of gravity of the cask (made of 304 stainless steel and depleted uranium) was assumed to be directly above the impact point. An elastic-plastic material constitutive model was used to calculate the nonlinear response of the cask components to the transient loading. Interactive color graphics (PATRAN and MOVIE BYU) were used throughout the analysis, proving to be extremely helpful for generation and verification of the geometry and boundary conditions of the finite element model and for interpretation of the analysis results. Results from the calculations show the cask sustained large localized deformations. However, these were almost entirely confined to the impact limiters built into the cask. The closure sections were determined to remain intact, and leakage would not be expected after the event. As an example of a large three-dimensional finite element dynamic impact calculation, this analysis can serve as an excellent benchmark for computer aided design procedures
The dimension split element-free Galerkin method for three-dimensional potential problems
Meng, Z. J.; Cheng, H.; Ma, L. D.; Cheng, Y. M.
2018-02-01
This paper presents the dimension split element-free Galerkin (DSEFG) method for three-dimensional potential problems, and the corresponding formulae are obtained. The main idea of the DSEFG method is that a three-dimensional potential problem can be transformed into a series of two-dimensional problems. For these two-dimensional problems, the improved moving least-squares (IMLS) approximation is applied to construct the shape function, which uses an orthogonal function system with a weight function as the basis functions. The Galerkin weak form is applied to obtain a discretized system equation, and the penalty method is employed to impose the essential boundary condition. The finite difference method is selected in the splitting direction. For the purposes of demonstration, some selected numerical examples are solved using the DSEFG method. The convergence study and error analysis of the DSEFG method are presented. The numerical examples show that the DSEFG method has greater computational precision and computational efficiency than the IEFG method.
Stefano Luisa
2005-01-01
/CREB fusion protein and a mutant of the PKA catalytic subunit that is targeted to the nucleus, we have shown that the glucose-6-phosphatase gene has two distinct genetic elements that function as bona fide CRE. This study further shows that the expression vectors encoding C2/CREB and catalytic subunit of PKA are valuable tools for the study of CREB-mediated gene transcription and the biological functions of CREB.
Numerical simulation of potato slices drying using a two-dimensional finite element model
Beigi Mohsen
2017-01-01
Full Text Available An experimental and numerical study was conducted to investigate the process of potato slices drying. For simulating the moisture transfer in the samples and predict the dehydration curves, a two-dimensional finite element model was developed and programmed in Compaq Visual Fortran, version 6.5. The model solved the Fick’s second law for slab in a shrinkage system to calculate the unsteady two-dimensional moisture transmission in rectangular coordinates (x,y. Moisture diffusivity and moisture transfer coefficient were determined by minimizing the sum squares of residuals between experimental and numerical predicted data. Shrinkage kinetics of the potato slices during dehydration was determined experimentally and found to be a linear function of removed moisture. The determined parameters were used in the mathematical model. The predicted moisture content values were compared to the experimental data and the validation results demonstrated that the dynamic drying curves were predicted by the methodology very well.
Finite Element Analysis of Three-Dimensional (3D Auxetic Textile Composite under Compression
Jifang Zeng
2018-03-01
Full Text Available This paper reports a finite element (FE analysis of three-dimensional (3D auxetic textile composite by using commercial software ANSYS 15 under compression. The two-dimensional (2D FE model was first developed and validated by experiment. Then, the validated model was used to evaluate effects of structural parameters and constituent material properties. For the comparison, 3D non-auxetic composite that was made with the same constituent materials and structural parameters, but with different yarn arrangement in the textile structure was also analyzed at the same time. The analysis results showed that the auxetic and non-auxetic composites have different compression behaviors and the auxetic composite has better the energy absorption capacity than the non-auxetic composite under the same compression stress. The study has provided us a guidance to design and fabricate auxetic composites with the required mechanical behavior by appropriately selecting structural parameters and constituent materials.
PARALLEL ALGORITHM FOR THREE-DIMENSIONAL STOKES FLOW SIMULATION USING BOUNDARY ELEMENT METHOD
D. G. Pribytok
2016-01-01
Full Text Available Parallel computing technique for modeling three-dimensional viscous flow (Stokes flow using direct boundary element method is presented. The problem is solved in three phases: sampling and construction of system of linear algebraic equations (SLAE, its decision and finding the velocity of liquid at predetermined points. For construction of the system and finding the velocity, the parallel algorithms using graphics CUDA cards programming technology have been developed and implemented. To solve the system of linear algebraic equations the implemented software libraries are used. A comparison of time consumption for three main algorithms on the example of calculation of viscous fluid motion in three-dimensional cavity is performed.
Li, N.; Cheng, Y. M.
2015-01-01
Landslide is a major disaster resulting in considerable loss of human lives and property damages in hilly terrain in Hong Kong, China and many other countries. The factor of safety and the critical slip surface for slope stabilization are the main considerations for slope stability analysis in the past, while the detailed post-failure conditions of the slopes have not been considered in sufficient detail. There is however increasing interest in the consequences after the initiation of failure that includes the development and propagation of the failure surfaces, the amount of failed mass and runoff and the affected region. To assess the development of slope failure in more detail and to consider the potential danger of slopes after failure has initiated, the slope stability problem under external surcharge is analyzed by the distinct element method (DEM) and a laboratory model test in the present research. A more refined study about the development of failure, microcosmic failure mechanisms and the post-failure mechanisms of slopes will be carried out. The numerical modeling method and the various findings from the present work can provide an alternate method of analysis of slope failure, which can give additional information not available from the classical methods of analysis.
Schickert, Martin
2015-01-01
Ultrasonic testing systems using transducer arrays and the SAFT (Synthetic Aperture Focusing Technique) reconstruction allow for imaging the internal structure of concrete elements. At one-sided access, three-dimensional representations of the concrete volume can be reconstructed in relatively great detail, permitting to detect and localize objects such as construction elements, built-in components, and flaws. Different SAFT data acquisition and processing schemes can be utilized which differ in terms of the measuring and computational effort and the reconstruction result. In this contribution, two methods are compared with respect to their principle of operation and their imaging characteristics. The first method is the conventional single-channel SAFT algorithm which is implemented using a virtual transducer that is moved within a transducer array by electronic switching. The second method is the Combinational SAFT algorithm (C-SAFT), also named Sampling Phased Array (SPA) or Full Matrix Capture/Total Focusing Method (TFM/FMC), which is realized using a combination of virtual transducers within a transducer array. Five variants of these two methods are compared by means of measurements obtained at test specimens containing objects typical of concrete elements. The automated SAFT imaging system FLEXUS is used for the measurements which includes a three-axis scanner with a 1.0 m × 0.8 m scan range and an electronically switched ultrasonic array consisting of 48 transducers in 16 groups. On the basis of two-dimensional and three-dimensional reconstructed images, qualitative and some quantitative results of the parameters image resolution, signal-to-noise ratio, measurement time, and computational effort are discussed in view of application characteristics of the SAFT variants
Mordant, Maurice.
1981-04-01
To solve a multigroup stationary neutron transport equation in two-dimensional geometries (X-Y), (R-O) or (R-Z) generally on uses discrete ordinates and rectangular meshes. The way to do it is then well known, well documented and somewhat obvious. If one needs to treat awkward geometries or distorted meshes, things are not so easy and the way to do it is no longer straightforward. We have studied this problem at Limeil Nuclear Center and as an alternative to Monte Carlo methods and code we have implemented in ZEPHYR code at least two efficient finite element solutions for Lagrangian meshes involving any kind of triangles and quadrilaterals
Three-dimensional analysis of eddy current with the finite element method
Takano, Ichiro; Suzuki, Yasuo
1977-05-01
The finite element method is applied to three-dimensional analysis of eddy current induced in a large Tokamak device (JT-60). Two techniques to study the eddy current are presented: those of ordinary vector potential and modified vector potential. The latter is originally developed for decreasing dimension of the global matrix. Theoretical treatment of these two is given. The skin effect for alternate current flowing in the circular loop of rectangular cross section is examined as an example of the modified vector potential technique, and the result is compared with analytical one. This technique is useful in analysis of the eddy current problem. (auth.)
Desai, V; Labby, Z; Culberson, W [University of Wisc Madison, Madison, WI (United States)
2016-06-15
Purpose: To determine whether body site-specific treatment plans form unique “plan class” clusters in a multi-dimensional analysis of plan complexity metrics such that a single beam quality correction determined for a representative plan could be universally applied within the “plan class”, thereby increasing the dosimetric accuracy of a detector’s response within a subset of similarly modulated nonstandard deliveries. Methods: We collected 95 clinical volumetric modulated arc therapy (VMAT) plans from four body sites (brain, lung, prostate, and spine). The lung data was further subdivided into SBRT and non-SBRT data for a total of five plan classes. For each control point in each plan, a variety of aperture-based complexity metrics were calculated and stored as unique characteristics of each patient plan. A multiple comparison of means analysis was performed such that every plan class was compared to every other plan class for every complexity metric in order to determine which groups could be considered different from one another. Statistical significance was assessed after correcting for multiple hypothesis testing. Results: Six out of a possible 10 pairwise plan class comparisons were uniquely distinguished based on at least nine out of 14 of the proposed metrics (Brain/Lung, Brain/SBRT lung, Lung/Prostate, Lung/SBRT Lung, Lung/Spine, Prostate/SBRT Lung). Eight out of 14 of the complexity metrics could distinguish at least six out of the possible 10 pairwise plan class comparisons. Conclusion: Aperture-based complexity metrics could prove to be useful tools to quantitatively describe a distinct class of treatment plans. Certain plan-averaged complexity metrics could be considered unique characteristics of a particular plan. A new approach to generating plan-class specific reference (pcsr) fields could be established through a targeted preservation of select complexity metrics or a clustering algorithm that identifies plans exhibiting similar
Ohsuga, Ken; Mineshige, Shin
2011-01-01
We present the detailed global structure of black hole accretion flows and outflows through newly performed two-dimensional radiation-magnetohydrodynamic simulations. By starting from a torus threaded with weak toroidal magnetic fields and by controlling the central density of the initial torus, ρ 0 , we can reproduce three distinct modes of accretion flow. In model A, which has the highest central density, an optically and geometrically thick supercritical accretion disk is created. The radiation force greatly exceeds the gravity above the disk surface, thereby driving a strong outflow (or jet). Because of mild beaming, the apparent (isotropic) photon luminosity is ∼22L E (where L E is the Eddington luminosity) in the face-on view. Even higher apparent luminosity is feasible if we increase the flow density. In model B, which has moderate density, radiative cooling of the accretion flow is so efficient that a standard-type, cold, and geometrically thin disk is formed at radii greater than ∼7 R S (where R S is the Schwarzschild radius), while the flow is radiatively inefficient otherwise. The magnetic-pressure-driven disk wind appears in this model. In model C, the density is too low for the flow to be radiatively efficient. The flow thus becomes radiatively inefficient accretion flow, which is geometrically thick and optically thin. The magnetic-pressure force, together with the gas-pressure force, drives outflows from the disk surface, and the flow releases its energy via jets rather than via radiation. Observational implications are briefly discussed.
Tao Ganqiang; Yu Qing; Xiao Xiao
2011-01-01
Viscous and incompressible fluid flow is important for numerous engineering mechanics problems. Because of high non linear and incompressibility for Navier-Stokes equation, it is very difficult to solve Navier-Stokes equation by numerical method. According to its characters of Navier-Stokes equation, quartic derivation controlling equation of the two dimensional incompressible Navier-Stokes equation is set up firstly. The method solves the problem for dealing with vorticity boundary and automatically meets incompressibility condition. Then Finite Element equation for Navier-Stokes equation is proposed by using quadratic quadrilateral unit with 8 nodes in which the unit function is quadratic and non linear.-Based on it, the Finite Element program of quadratic quadrilateral unit with 8 nodes is developed. Lastly, numerical experiment proves the accuracy and dependability of the method and also shows the method has good application prospect in computational fluid mechanics. (authors)
Computational Performance of a Parallelized Three-Dimensional High-Order Spectral Element Toolbox
Bosshard, Christoph; Bouffanais, Roland; Clémençon, Christian; Deville, Michel O.; Fiétier, Nicolas; Gruber, Ralf; Kehtari, Sohrab; Keller, Vincent; Latt, Jonas
In this paper, a comprehensive performance review of an MPI-based high-order three-dimensional spectral element method C++ toolbox is presented. The focus is put on the performance evaluation of several aspects with a particular emphasis on the parallel efficiency. The performance evaluation is analyzed with help of a time prediction model based on a parameterization of the application and the hardware resources. A tailor-made CFD computation benchmark case is introduced and used to carry out this review, stressing the particular interest for clusters with up to 8192 cores. Some problems in the parallel implementation have been detected and corrected. The theoretical complexities with respect to the number of elements, to the polynomial degree, and to communication needs are correctly reproduced. It is concluded that this type of code has a nearly perfect speed up on machines with thousands of cores, and is ready to make the step to next-generation petaflop machines.
FEAST: a two-dimensional non-linear finite element code for calculating stresses
Tayal, M.
1986-06-01
The computer code FEAST calculates stresses, strains, and displacements. The code is two-dimensional. That is, either plane or axisymmetric calculations can be done. The code models elastic, plastic, creep, and thermal strains and stresses. Cracking can also be simulated. The finite element method is used to solve equations describing the following fundamental laws of mechanics: equilibrium; compatibility; constitutive relations; yield criterion; and flow rule. FEAST combines several unique features that permit large time-steps in even severely non-linear situations. The features include a special formulation for permitting many finite elements to simultaneously cross the boundary from elastic to plastic behaviour; accomodation of large drops in yield-strength due to changes in local temperature and a three-step predictor-corrector method for plastic analyses. These features reduce computing costs. Comparisons against twenty analytical solutions and against experimental measurements show that predictions of FEAST are generally accurate to ± 5%
Three-dimensional finite element analysis of implant-assisted removable partial dentures.
Eom, Ju-Won; Lim, Young-Jun; Kim, Myung-Joo; Kwon, Ho-Beom
2017-06-01
Whether the implant abutment in implant-assisted removable partial dentures (IARPDs) functions as a natural removable partial denture (RPD) tooth abutment is unknown. The purpose of this 3-dimensional finite element study was to analyze the biomechanical behavior of implant crown, bone, RPD, and IARPD. Finite element models of the partial maxilla, teeth, and prostheses were generated on the basis of a patient's computed tomographic data. The teeth, surveyed crowns, and RPDs were created in the model. With the generated components, four 3-dimensional finite element models of the partial maxilla were constructed: tooth-supported RPD (TB), implant-supported RPD (IB), tooth-tissue-supported RPD (TT), and implant-tissue-supported RPD (IT) models. Oblique loading of 300 N was applied on the crowns and denture teeth. The von Mises stress and displacement of the denture abutment tooth and implant system were identified. The highest von Mises stress values of both IARPDs occurred on the implants, while those of both natural tooth RPDs occurred on the frameworks of the RPDs. The highest von Mises stress of model IT was about twice that of model IB, while the value of model TT was similar to that of model TB. The maximum displacement was greater in models TB and TT than in models IB and IT. Among the 4 models, the highest maximum displacement value was observed in the model TT and the lowest value was in the model IB. Finite element analysis revealed that the stress distribution pattern of the IARPDs was different from that of the natural tooth RPDs and the stress distribution of implant-supported RPD was different from that of implant-tissue-supported RPD. When implants are used for RPD abutments, more consideration concerning the RPD design and the number or location of the implant is necessary. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.
hree-Dimensional Finite Element Simulation of the Buried Pipe Problem in Geogrid Reinforced Soil
Mohammed Yousif Fattah
2016-05-01
Full Text Available Buried pipeline systems are commonly used to transport water, sewage, natural oil/gas and other materials. The beneficial of using geogrid reinforcement is to increase the bearing capacity of the soil and decrease the load transfer to the underground structures. This paper deals with simulation of the buried pipe problem numerically by finite elements method using the newest version of PLAXIS-3D software. Rajkumar and Ilamaruthi's study, 2008 has been selected to be reanalyzed as 3D problem because it is containing all the properties needed by the program such as the modulus of elasticity, Poisson's ratio, angle of internal friction. It was found that the results of vertical crown deflection for the model without geogrid obtained from PLAXIS-3D are higher than those obtained by two-dimensional plane strain by about 21.4% while this percent becomes 12.1 for the model with geogrid, but in general, both have the same trend. The two dimensional finite elements analysis predictions of pipe-soil system behavior indicate an almost linear displacement of pipe deflection with applied pressure while 3-D analysis exhibited non-linear behavior especially at higher loads.
Lee, Young-Woo; Yeo, Seunghwan; Cho, Moon Sung
2015-01-01
The carbonization is a process step where the binder that is incorporated during the matrix graphite powder preparation step is evaporated and the residue of the binder is carbonized during the heat treatment at about 1073 K. This carbonization step is followed by the final high temperature heat treatment where the carbonized compacts are heat treated at 2073-2173 K in vacuum for a relatively short time (about 2 hrs). In order to develop a fuel compact fabrication technology, and for fuel matrix graphite to meet the required material properties, it is essential to investigate the relationship among the process parameters of the matrix graphite powder preparation, the fabrication parameters of fuel element green compact and the heat treatments conditions, which has a strong influence on the further steps and the material properties of fuel element. In this work, the dimensional changes of green compacts during the carbonization and final heat treatment are evaluated when compacts have different densities from different pressing conditions and different final heat treatment temperatures are employed, keeping other process parameters constant, such as the binder content, carbonization time, temperature and atmosphere (two hours ant 1073K and N2 atmosphere). In this work, the dimensional variations of green compacts during the carbonization and final heat treatment are evaluated when compacts have different densities from different pressing conditions and different final heat treatment temperatures are employed
Marcato, G.; Fujisawa, K.; Mantovani, M.; Pasuto, A.; Silvano, S.; Tagliavini, F.; Zabuski, L.
2007-11-01
The aim of the paper is to present the modelling of the ground effects of seismic waves on a large debris deposit lying on a steep mountain slope, with particular attention paid to the potential triggering of slope movements. The study site is a mass of 2.5 million m3 rock fall deposit, named "Monte Salta Landslide", located on the northern slope of the Vajont valley, at the border between Veneto and Friuli Venezia Giulia regions in north-eastern Italy. Several historical landslide events were reported in the area in the past, first one dating back to the 17th century. The landslide deposit completely mantles the slope with a thick cover of rock blocks. The Mt. Salta landslide is conditioned by the presence of Mt. Borgà regional thrust, which uplifts Jurassic limestone on the top of Cretaceous rock units. Above the thrust zone, folded and highly fractured rock mass dips steeply towards the slope free face, producing highly unstable setting. The study area has been classified as high seismic hazard and different vulnerable elements can be affected by the remobilisation of debris, among which a village, a national road and a big quarry that was opened, with the intent to exploit the part of the landslide deposit for construction purposes. In this study, numerical analysis was performed, to simulate the slope behaviour using distinct element method and applying UDEC code. The 2-D models were built on three cross-sections and elasto-plastic behaviour was assumed, both for rock matrix and discontinuities. The earthquake effect was modelled in pseudo-dynamic way, i.e. by magnifying the acceleration and applying also its horizontal component. The expected seismic acceleration in the study area was calculated on the basis of previous studies as equal to 0.28 g. The results proved that the increase of the vertical component alone has a small influence on the deformational behaviour of the system. Hence, the acceleration vector was deviated at 5° and then at 10° from the
G. Marcato
2007-11-01
Full Text Available The aim of the paper is to present the modelling of the ground effects of seismic waves on a large debris deposit lying on a steep mountain slope, with particular attention paid to the potential triggering of slope movements.
The study site is a mass of 2.5 million m^{3} rock fall deposit, named "Monte Salta Landslide", located on the northern slope of the Vajont valley, at the border between Veneto and Friuli Venezia Giulia regions in north-eastern Italy.
Several historical landslide events were reported in the area in the past, first one dating back to the 17th century. The landslide deposit completely mantles the slope with a thick cover of rock blocks.
The Mt. Salta landslide is conditioned by the presence of Mt. Borgà regional thrust, which uplifts Jurassic limestone on the top of Cretaceous rock units. Above the thrust zone, folded and highly fractured rock mass dips steeply towards the slope free face, producing highly unstable setting.
The study area has been classified as high seismic hazard and different vulnerable elements can be affected by the remobilisation of debris, among which a village, a national road and a big quarry that was opened, with the intent to exploit the part of the landslide deposit for construction purposes.
In this study, numerical analysis was performed, to simulate the slope behaviour using distinct element method and applying UDEC code. The 2-D models were built on three cross-sections and elasto-plastic behaviour was assumed, both for rock matrix and discontinuities. The earthquake effect was modelled in pseudo-dynamic way, i.e. by magnifying the acceleration and applying also its horizontal component. The expected seismic acceleration in the study area was calculated on the basis of previous studies as equal to 0.28 g.
The results proved that the increase of the vertical component alone has a small influence on the deformational behaviour of the
Application of three dimensional finite element modeling for the simulation of machining processes
Fischer, C.E.; Wu, W.T.; Chigurupati, P.; Jinn, J.T.
2004-01-01
For many years, metal cutting simulations have been performed using two dimensional approximations of the actual process. Factors such as chip morphology, cutting force, temperature, and tool wear can all be predicted on the computer. However, two dimensional simulation is limited to processes which are orthogonal, or which can be closely approximated as orthogonal.Advances in finite element technology, coupled with continuing improvement in the availability of low cost, high performance computer hardware, have made the three dimensional simulation of a large variety of metal cutting processes practical. Specific improvements include efficient FEM solvers, and robust adaptive remeshing. As researchers continue to gain an improved understanding of wear, material representation, tool coatings, fracture, and other such phenomena, the machining simulation system also must adapt to incorporate these evolving models.To demonstrate the capabilities of the 3D simulation system, a variety of drilling, milling, and turning processes have been simulated and will be presented in this paper. Issues related to computation time and simulation accuracy will also be addressed
Seismic response of three-dimensional rockfill dams using the Indirect Boundary Element Method
Sanchez-Sesma, Francisco J; Arellano-Guzman, Mauricio; Perez-Gavilan, Juan J; Suarez, Martha; Marengo-Mogollon, Humberto; Chaillat, Stephanie; Jaramillo, Juan Diego; Gomez, Juan; Iturraran-Viveros, Ursula; Rodriguez-Castellanos, Alejandro
2010-01-01
The Indirect Boundary Element Method (IBEM) is used to compute the seismic response of a three-dimensional rockfill dam model. The IBEM is based on a single layer integral representation of elastic fields in terms of the full-space Green function, or fundamental solution of the equations of dynamic elasticity, and the associated force densities along the boundaries. The method has been applied to simulate the ground motion in several configurations of surface geology. Moreover, the IBEM has been used as benchmark to test other procedures. We compute the seismic response of a three-dimensional rockfill dam model placed within a canyon that constitutes an irregularity on the surface of an elastic half-space. The rockfill is also assumed elastic with hysteretic damping to account for energy dissipation. Various types of incident waves are considered to analyze the physical characteristics of the response: symmetries, amplifications, impulse response and the like. Computations are performed in the frequency domain and lead to time response using Fourier analysis. In the present implementation a symmetrical model is used to test symmetries. The boundaries of each region are discretized into boundary elements whose size depends on the shortest wavelength, typically, six boundary segments per wavelength. Usually, the seismic response of rockfill dams is simulated using either finite elements (FEM) or finite differences (FDM). In most applications, commercial tools that combine features of these methods are used to assess the seismic response of the system for a given motion at the base of model. However, in order to consider realistic excitation of seismic waves with different incidence angles and azimuth we explore the IBEM.
Gheorghe, G.; Man, I.
2015-01-01
During irradiation in the nuclear reactor, fuel elements undergo dimensional and structural changes, and changes of sheath surface condition as well, which can lead to damages and even loss of integrity. This paper presents the results of dimensional measurements and of examination technique with eddy currents for three fuel elements of an irradiated CANDU fuel bundle. One of the fuel elements (FE), which is studied in detail, presented a crack about 40 mm long. The purpose of these nondestructive examination techniques is to determine those parameters that characterize the behavior and performance of nuclear fuel operation. This paper contains images of defects and interpretations of the causes of their occurrence. (authors)
A Galleria Boundary Element Method for two-dimensional nonlinear magnetostatics
Brovont, Aaron D.
The Boundary Element Method (BEM) is a numerical technique for solving partial differential equations that is used broadly among the engineering disciplines. The main advantage of this method is that one needs only to mesh the boundary of a solution domain. A key drawback is the myriad of integrals that must be evaluated to populate the full system matrix. To this day these integrals have been evaluated using numerical quadrature. In this research, a Galerkin formulation of the BEM is derived and implemented to solve two-dimensional magnetostatic problems with a focus on accurate, rapid computation. To this end, exact, closed-form solutions have been derived for all the integrals comprising the system matrix as well as those required to compute fields in post-processing; the need for numerical integration has been eliminated. It is shown that calculation of the system matrix elements using analytical solutions is 15-20 times faster than with numerical integration of similar accuracy. Furthermore, through the example analysis of a c-core inductor, it is demonstrated that the present BEM formulation is a competitive alternative to the Finite Element Method (FEM) for linear magnetostatic analysis. Finally, the BEM formulation is extended to analyze nonlinear magnetostatic problems via the Dual Reciprocity Method (DRBEM). It is shown that a coarse, meshless analysis using the DRBEM is able to achieve RMS error of 3-6% compared to a commercial FEM package in lightly saturated conditions.
Jiang-Jun Zhou
2017-01-01
Full Text Available In this study, we developed and validated a refined three-dimensional finite element model of middle femoral comminuted fracture to compare the biomechanical stability after two kinds of plate fixation: a newly designed assembly locking compression plate (NALCP and a locking compression plate (LCP. CT data of a male volunteer was converted to middle femoral comminuted fracture finite element analysis model. The fracture was fixated by NALCP and LCP. Stress distributions were observed. Under slow walking load and torsion load, the stress distribution tendency of the two plates was roughly uniform. The anterolateral femur was the tension stress area, and the bone block shifted toward the anterolateral femur. Maximum stress was found on the lateral border of the number 5 countersink of the plate. Under a slow walking load, the NALCP maximum stress was 2.160e+03 MPa and the LCP was 8.561e+02 MPa. Under torsion load, the NALCP maximum stress was 2.260e+03 MPa and the LCP was 6.813e+02 MPa. Based on those results of finite element analysis, the NALCP can provide adequate mechanical stability for comminuted fractures, which would help fixate the bone block and promote bone healing.
Kuwabara, Y.; Ogiwara, Y.; Suzuki, T.; Tsuchiya, H.; Nakayama, M.
1981-01-01
It is generally recognized that the earthquake response of a structure can be significantly affected by the dynamic interaction between the structure and the surrounding soil. Dynamic soil-structure interaction effects are usually analyzed by using a lumped mass model or a finite element model. In the lumped mass model, the soil is represented by springs and dashpots based on the half-space elastic theory. Each model has its advantages and limitations. The Three Dimensional Thin Layered Element Theory has been developed by Dr. Hiroshi Tajimi based on the combined results of the abovementioned lumped mass model and finite element model. The main characteristic of this theory is that, in consideration and can be applied in the analysis of many problems in soil-structure interaction, such as those involving radiation damping, embedded structures, and multi-layered soil deposits. This paper describes test results on a small scale model used to prove the validity of the computer program based on the Thin Layered Element Theory. As a numerical example, the response analysis of a PWR nuclear power plant is carried out using this program. The vibration test model is simplified and the scale is 1/750 for line. The soil layer of the model is made of congealed gelatine. The test soil layer is 80 cm long, 35 cm wide and 10 cm thick. The super structure is a one mass model made of metal sheet spring and solid mass metal. As fixed inputs, sinusoidal waves (10, 20 gal level) are used. The displacements of the top and base of the super structure, and the accelerations and the displacements of the shaking table are measured. The main parameter of the test is the shear wave velocity of the soil layer. (orig./RW)
Peng, Kuan; He, Ling; Zhu, Ziqiang; Tang, Jingtian; Xiao, Jiaying
2013-12-01
Compared with commonly used analytical reconstruction methods, the frequency-domain finite element method (FEM) based approach has proven to be an accurate and flexible algorithm for photoacoustic tomography. However, the FEM-based algorithm is computationally demanding, especially for three-dimensional cases. To enhance the algorithm's efficiency, in this work a parallel computational strategy is implemented in the framework of the FEM-based reconstruction algorithm using a graphic-processing-unit parallel frame named the "compute unified device architecture." A series of simulation experiments is carried out to test the accuracy and accelerating effect of the improved method. The results obtained indicate that the parallel calculation does not change the accuracy of the reconstruction algorithm, while its computational cost is significantly reduced by a factor of 38.9 with a GTX 580 graphics card using the improved method.
Wu, Xian-Qian; Wang, Xi; Wei, Yan-Peng; Song, Hong-Wei; Huang, Chen-Guang
2012-06-01
Shot peening is a widely used surface treatment method by generating compressive residual stress near the surface of metallic materials to increase fatigue life and resistance to corrosion fatigue, cracking, etc. Compressive residual stress and dent profile are important factors to evaluate the effectiveness of shot peening process. In this paper, the influence of dimensionless parameters on maximum compressive residual stress and maximum depth of the dent were investigated. Firstly, dimensionless relations of processing parameters that affect the maximum compressive residual stress and the maximum depth of the dent were deduced by dimensional analysis method. Secondly, the influence of each dimensionless parameter on dimensionless variables was investigated by the finite element method. Furthermore, related empirical formulas were given for each dimensionless parameter based on the simulation results. Finally, comparison was made and good agreement was found between the simulation results and the empirical formula, which shows that a useful approach is provided in this paper for analyzing the influence of each individual parameter.
Gozin, Mohammad-Hosein; Aghaie-Khafri, Mehrdad [K. N. Toosi University of Technology, Tehran (Korea, Republic of)
2014-06-15
Shape evolution of a quarter-elliptical crack emanating from a hole is studied. Three dimensional elastic-plastic finite element analysis of the fatigue crack closure was considered and the stress intensity factor was calculated based on the duplicated elastic model at each crack tip node. The crack front node was advanced proportional to the imposed effective stress intensity factor. Remeshing was applied at each step of the crack growth and solution mapping algorithm was considered. Crack growth retardation at free surfaces was successfully observed. A MATLAB-ABAQUS interference code was developed for the first time to perform crack growth on the basis of crack closure. Simulation results indicated that crack shape is sensitive to the remeshing strategy. Predictions based on the proposed models were in good agreement with Carlson's experiments results.
Hutchinson, S.; Costillo, S.; Dalton, K.; Hensel, E.
1990-01-01
A study is conducted of the finite element solution of the partial differential equations governing two-dimensional electromagnetic field scattering problems on a SIMD computer. A nodal assembly technique is introduced which maps a single node to a single processor. The physical domain is first discretized in parallel to yield the node locations of an O-grid mesh. Next, the system of equations is assembled and then solved in parallel using a conjugate gradient algorithm for complex-valued, non-symmetric, non-positive definite systems. Using this technique and Thinking Machines Corporation's Connection Machine-2 (CM-2), problems with more than 250k nodes are solved. Results of electromagnetic scattering, governed by the 2-d scalar Hemoholtz wave equations are presented in this paper. Solutions are demonstrated for a wide range of objects. A summary of performance data is given for the set of test problems
Three-dimensional finite element modelling of the uniaxial tension test
Østergaard, Lennart; Stang, Henrik
2002-01-01
. One of the most direct methods for determination of the σ-w relationship is the uniaxial tension test, where a notched specimen is pulled apart while the tensile load and the crack opening displacement is observed. This method is appealing since the interpretation is straightforward. The method......Experimental determination of the stress-crack opening relationship (σ-w) for concrete as defined in the fictitious crack model has proven to be difficult. This is due to the problems that may arise from application of the inverse analysis method necessary for the derivation of the relationship...... is examined in this paper through three dimensional finite element analyses. It is concluded that the interpretation of the uniaxial tension test is indeed straightforward, if the testing machine stiffness is sufficiently high....
Itagaki, Masafumi; Sahashi, Naoki.
1996-01-01
The multiple reciprocity method (MRM) in conjunction with the boundary element method has been employed to solve one-group eigenvalue problems described by the three-dimensional (3-D) neutron diffusion equation. The domain integral related to the fission source is transformed into a series of boundary-only integrals, with the aid of the higher order fundamental solutions based on the spherical and the modified spherical Bessel functions. Since each degree of the higher order fundamental solutions in the 3-D cases has a singularity of order (1/r), the above series of boundary integrals requires additional terms which do not appear in the 2-D MRM formulation. The critical eigenvalue itself can be also described using only boundary integrals. Test calculations show that Wielandt's spectral shift technique guarantees rapid and stable convergence of 3-D MRM computations. (author)
Chang, T.Y.; Prachuktam, S.; Reich, M.
1975-01-01
The formulation of the stiffness equation for an 8 to 21 node isoparametric element with elastic-plastic material and large deformation is presented. The formulation has been implemented in a nonlinear finite element program for the analysis of three-dimensional continuums. To demonstrate the utility of the formulation, a thick-walled cylinder was analyzed and the results are compared favorably with a known solution. The element type presented can be applied not only to 3-D continuums, but also to plate or shell structures, for which degenerated isoparametric elements may be used
Boundary element methods applied to two-dimensional neutron diffusion problems
Itagaki, Masafumi
1985-01-01
The Boundary element method (BEM) has been applied to two-dimensional neutron diffusion problems. The boundary integral equation and its discretized form have been derived. Some numerical techniques have been developed, which can be applied to critical and fixed-source problems including multi-region ones. Two types of test programs have been developed according to whether the 'zero-determinant search' or the 'source iteration' technique is adopted for criticality search. Both programs require only the fluxes and currents on boundaries as the unknown variables. The former allows a reduction in computing time and memory in comparison with the finite element method (FEM). The latter is not always efficient in terms of computing time due to the domain integral related to the inhomogeneous source term; however, this domain integral can be replaced by the equivalent boundary integral for a region with a non-multiplying medium or with a uniform source, resulting in a significant reduction in computing time. The BEM, as well as the FEM, is well suited for solving irregular geometrical problems for which the finite difference method (FDM) is unsuited. The BEM also solves problems with infinite domains, which cannot be solved by the ordinary FEM and FDM. Some simple test calculations are made to compare the BEM with the FEM and FDM, and discussions are made concerning the relative merits of the BEM and problems requiring future solution. (author)
A three-dimensional finite element model for biomechanical analysis of the hip.
Chen, Guang-Xing; Yang, Liu; Li, Kai; He, Rui; Yang, Bin; Zhan, Yan; Wang, Zhi-Jun; Yu, Bing-Nin; Jian, Zhe
2013-11-01
The objective of this study was to construct a three-dimensional (3D) finite element model of the hip. The images of the hip were obtained from Chinese visible human dataset. The hip model includes acetabular bone, cartilage, labrum, and bone. The cartilage of femoral head was constructed using the AutoCAD and Solidworks software. The hip model was imported into ABAQUS analysis system. The contact surface of the hip joint was meshed. To verify the model, the single leg peak force was loaded, and contact area of the cartilage and labrum of the hip and pressure distribution in these structures were observed. The constructed 3D hip model reflected the real hip anatomy. Further, this model reflected biomechanical behavior similar to previous studies. In conclusion, this 3D finite element hip model avoids the disadvantages of other construction methods, such as imprecision of cartilage construction and the absence of labrum. Further, it provides basic data critical for accurately modeling normal and abnormal loads, and the effects of abnormal loads on the hip.
Johnson, Kyle; Thurow, Brian; Kim, Taehoon; Blois, Gianluca; Christensen, Kenneth
2016-11-01
Three-dimensional, three-component (3D-3C) measurements were made using a plenoptic camera on the flow around a roughness element immersed in a turbulent boundary layer. A refractive index matched approach allowed whole-field optical access from a single camera to a measurement volume that includes transparent solid geometries. In particular, this experiment measures the flow over a single hemispherical roughness element made of acrylic and immersed in a working fluid consisting of Sodium Iodide solution. Our results demonstrate that plenoptic particle image velocimetry (PIV) is a viable technique to obtaining statistically-significant volumetric velocity measurements even in a complex separated flow. The boundary layer to roughness height-ratio of the flow was 4.97 and the Reynolds number (based on roughness height) was 4.57×103. Our measurements reveal key flow features such as spiraling legs of the shear layer, a recirculation region, and shed arch vortices. Proper orthogonal decomposition (POD) analysis was applied to the instantaneous velocity and vorticity data to extract these features. Supported by the National Science Foundation Grant No. 1235726.
Yao, Kai; Shen, Kai; Wang, Zheng-Dao; Wang, Yue-Sheng
2014-01-01
In this study, 3D finite element analysis is presented by calculating the residual magnetic field signals of ferromagnets under the plastic deformation. The contour maps of tangential and normal RMF gradients are given, and the 3D effect is discussed. The results show that the tangential peak–peak amplitude and normal peak–vale amplitude are remarkably different in 2D and 3D simulations, but the tangential peak–peak width and normal peak–vale width are similar. Moreover, some key points are capable of capturing the plastic-zone shape, especially when the lift-off is small enough. The present study suggests an effective defect identification method with Metal magnetic memory (MMM) technique. - Highlights: • Three-dimensional (3D) finite element analysis is presented by calculating the residual magnetic field signals of ferromagnets under the plastic deformation. • The contour maps of gradients of the tangential and normal residual magnetic fields are given, and the 3D effect is discussed. • The present study suggests an effective defect identification method with metal magnetic memory technique
Li, Zuoping; Alonso, Jorge E; Kim, Jong-Eun; Davidson, James S; Etheridge, Brandon S; Eberhardt, Alan W
2006-09-01
Three-dimensional finite element (FE) models of human pubic symphyses were constructed from computed tomography image data of one male and one female cadaver pelvis. The pubic bones, interpubic fibrocartilaginous disc and four pubic ligaments were segmented semi-automatically and meshed with hexahedral elements using automatic mesh generation schemes. A two-term viscoelastic Prony series, determined by curve fitting results of compressive creep experiments, was used to model the rate-dependent effects of the interpubic disc and the pubic ligaments. Three-parameter Mooney-Rivlin material coefficients were calculated for the discs using a heuristic FE approach based on average experimental joint compression data. Similarly, a transversely isotropic hyperelastic material model was applied to the ligaments to capture average tensile responses. Linear elastic isotropic properties were assigned to bone. The applicability of the resulting models was tested in bending simulations in four directions and in tensile tests of varying load rates. The model-predicted results correlated reasonably with the joint bending stiffnesses and rate-dependent tensile responses measured in experiments, supporting the validity of the estimated material coefficients and overall modeling approach. This study represents an important and necessary step in the eventual development of biofidelic pelvis models to investigate symphysis response under high-energy impact conditions, such as motor vehicle collisions.
Jensen, Erik Østergaard; Marcker, Kjeld A; Schell, J
1988-01-01
Nuclear extracts from soybean nodules, leaves and roots were used to investigate protein-DNA interactions in the 5' upstream (promoter) region of the soybean leghaemoglobin lbc(3) gene. Two distinct regions were identified which strongly bind a nodule specific factor. A Bal31 deletion analysis......, but with different affinities. Elements 1 and 2 share a common motif, although their AT-rich DNA sequences differ. Element 2 is highly conserved at an analogous position in other soybean lb gene 5' upstream regions. Udgivelsesdato: 1988-May...
Ishimaru, Makoto; Tochigi, Hitoshi; Nakajima, Masato; Shirai, Koji
2012-01-01
Recently, importance of evaluation for impact of earthquake-induced slope failure on nearby critical structures is increasing in order to evaluate seismic stability of the slope, in addition to evaluating the possibilities of slope failure. In this study, we presented an examination flow chart to evaluate the impact on structures after slope failure. In the examination flow chart, we assumed the following four considerations; (1) evaluation of the collapse region of the slope, (2) evaluation of behavior of the collapsed rock masses, (3) evaluation of the impact on the structures, (4) examination of the countermeasures. And, for the purpose of using three dimensional distinct element method (DEM) for evaluation of behavior of the collapsed rock masses, we firstly confirmed applicability of DEM to behavior of a mass hurtling down the slope by means of comparing with the model test results. Moreover, we clarified influence of initial position or restitution coefficient of rock masses on final traveling distance of collapsed rock masses. (author)
Fazi, Giovanni; Tellini, Simone; Vangi, Dario; Branchi, Roberto
2011-01-01
The distribution of stresses in bone, implants, and prosthesis were analyzed via three-dimensional finite element modeling in different implant configurations for a fixed implant-supported prosthesis in an edentulous mandible. A finite element model was created with data obtained from computed tomographic scans of a human mandible. Anisotropic characteristics for cortical and cancellous bone were incorporated into the model. Six different configurations of intraforaminal implants were tested, with the number of implants varying from three to five and the distal implants inserted either parallel to the other implants or tilted distally by 17 or 34 degrees. A prosthetic structure connecting the implants was designed, with 20-mm posterior cantilevers for the parallel implant configurations, and a load of 200 N was applied to the distal portion of the cantilevers. Stresses were measured at the level of the implant, the prosthetic structure, and the bone. Bone-level stresses were analyzed at the implant-bone interface, at the external cortical bone surface, distal to the terminal implant, and in the cancellous bone along the implant body. A three-parallel-implant configuration resulted in higher stress in the implant and bone than configurations with four or five parallel implants. Configurations with the distal implants tilted resulted in a more favorable stress distribution at all levels. In parallel-implant configurations for fixed implant-supported mandibular prostheses, four and five implants resulted in similar stress distribution in the bone, framework, and implants. A distribution of four implants with the distal implants tilted 34 degrees (ie, the "All-on-Four" configuration) resulted in a favorable reduction of stresses in the bone, framework, and implants.
Geramizadeh, Maryam; Katoozian, Hamidreza; Amid, Reza; Kadkhodazadeh, Mahdi
2018-04-01
This study aimed to optimize the thread depth and pitch of a recently designed dental implant to provide uniform stress distribution by means of a response surface optimization method available in finite element (FE) software. The sensitivity of simulation to different mechanical parameters was also evaluated. A three-dimensional model of a tapered dental implant with micro-threads in the upper area and V-shaped threads in the rest of the body was modeled and analyzed using finite element analysis (FEA). An axial load of 100 N was applied to the top of the implants. The model was optimized for thread depth and pitch to determine the optimal stress distribution. In this analysis, micro-threads had 0.25 to 0.3 mm depth and 0.27 to 0.33 mm pitch, and V-shaped threads had 0.405 to 0.495 mm depth and 0.66 to 0.8 mm pitch. The optimized depth and pitch were 0.307 and 0.286 mm for micro-threads and 0.405 and 0.808 mm for V-shaped threads, respectively. In this design, the most effective parameters on stress distribution were the depth and pitch of the micro-threads based on sensitivity analysis results. Based on the results of this study, the optimal implant design has micro-threads with 0.307 and 0.286 mm depth and pitch, respectively, in the upper area and V-shaped threads with 0.405 and 0.808 mm depth and pitch in the rest of the body. These results indicate that micro-thread parameters have a greater effect on stress and strain values.
Weitzman, Morley
1992-07-15
A three-dimensional finite-element code was developed and used to simulate the flow of groundwater towards an excavation in a saturated porous medium, allowing for seepage faces. An iterative procedure was used to predict the movement of the water table and the seepage flux. The numerical solution agreed well with experimental results from a sandbox experiment. (auth)
S. N. S. Jamaludin
2014-01-01
Full Text Available The composition of hydroxyapatite (HA as the ceramic phase and titanium (Ti as the metallic phase in HA/Ti functionally graded materials (FGMs shows an excellent combination of high biocompatibility and high mechanical properties in a structure. Because the gradation of these properties is one of the factors that affects the response of the functionally graded (FG plates, this paper is presented to show the domination of the grading parameter on the displacement and stress distribution of the plates. A three-dimensional (3D thermomechanical model of a 20-node brick quadratic element is used in the simulation of the thermoelastic behaviors of HA/Ti FG plates subjected to constant and functional thermal, mechanical, and thermomechanical loadings. The convergence properties of the present results are examined thoroughly in order to assess the accuracy of the theory applied and to compare them with the established research results. Instead of the grading parameter, this study reveals that the loading field distribution can be another factor that reflects the thermoelastic properties of the HA/Ti FG plates. The FG structure is found to be able to withstand the thermal stresses while preserving the high toughness properties and thus shows its ability to operate at high temperature.
Electrothermal Equivalent Three-Dimensional Finite-Element Model of a Single Neuron.
Cinelli, Ilaria; Destrade, Michel; Duffy, Maeve; McHugh, Peter
2018-06-01
We propose a novel approach for modelling the interdependence of electrical and mechanical phenomena in nervous cells, by using electrothermal equivalences in finite element (FE) analysis so that existing thermomechanical tools can be applied. First, the equivalence between electrical and thermal properties of the nerve materials is established, and results of a pure heat conduction analysis performed in Abaqus CAE Software 6.13-3 are validated with analytical solutions for a range of steady and transient conditions. This validation includes the definition of equivalent active membrane properties that enable prediction of the action potential. Then, as a step toward fully coupled models, electromechanical coupling is implemented through the definition of equivalent piezoelectric properties of the nerve membrane using the thermal expansion coefficient, enabling prediction of the mechanical response of the nerve to the action potential. Results of the coupled electromechanical model are validated with previously published experimental results of deformation for squid giant axon, crab nerve fibre, and garfish olfactory nerve fibre. A simplified coupled electromechanical modelling approach is established through an electrothermal equivalent FE model of a nervous cell for biomedical applications. One of the key findings is the mechanical characterization of the neural activity in a coupled electromechanical domain, which provides insights into the electromechanical behaviour of nervous cells, such as thinning of the membrane. This is a first step toward modelling three-dimensional electromechanical alteration induced by trauma at nerve bundle, tissue, and organ levels.
Lacey, G.; Thenoux, G.; Rodriguez-Roa, F.
2008-01-01
In accordance with the present development of empirical-mechanistic tools, this paper presents an alternative to traditional analysis methods for flexible pavements using a three-dimensional finite element formulation based on a liner-elastic perfectly-plastic Drucker-Pager model for granular soil layers and a linear-elastic stress-strain law for the asphalt layer. From the sensitivity analysis performed, it was found that variations of +-4 degree in the internal friction angle of granular soil layers did not significantly affect the analyzed pavement response. On the other hand, a null dilation angle is conservatively proposed for design purposes. The use of a Light Falling Weight Deflectometer is also proposed as an effective and practical tool for on-site elastic modulus determination of granular soil layers. However, the stiffness value obtained from the tested layer should be corrected when the measured peak deflection and the peak force do not occur at the same time. In addition, some practical observations are given to achieve successful field measurements. The importance of using a 3D FE analysis to predict the maximum tensile strain at the bottom of the asphalt layer (related to pavement fatigue) and the maximum vertical comprehensive strain transmitted to the top of the granular soil layers (related to rutting) is also shown. (author)
Two dimensional finite element modelling for dynamic water diffusion through stratum corneum.
Xiao, Perry; Imhof, Robert E
2012-10-01
Solvents penetration through in vivo human stratum corneum (SC) has always been an interesting research area for trans-dermal drug delivery studies, and the importance of intercellular routes (diffuse in between corneocytes) and transcellular routes (diffuse through corneocytes) during diffusion is often debatable. In this paper, we have developed a two dimensional finite element model to simulate the dynamic water diffusion through the SC. It is based on the brick-and-mortar model, with brick represents corneocytes and mortar represents lipids, respectively. It simulates the dynamic water diffusion process through the SC from pre-defined initial conditions and boundary conditions. Although the simulation is based on water diffusions, the principles can also be applied to the diffusions of other topical applied substances. The simulation results show that both intercellular routes and transcellular routes are important for water diffusion. Although intercellular routes have higher flux rates, most of the water still diffuse through transcellular routes because of the high cross area ratio of corneocytes and lipids. The diffusion water flux, or trans-epidermal water loss (TEWL), is reversely proportional to corneocyte size, i.e. the larger the corneocyte size, the lower the TEWL, and vice versa. There is also an effect of the SC thickness, external air conditions and diffusion coefficients on the water diffusion through SC on the resulting TEWL. Copyright © 2012 Elsevier B.V. All rights reserved.
Neng Wan
2014-01-01
Full Text Available In terms of the poor geometric adaptability of spline element method, a geometric precision spline method, which uses the rational Bezier patches to indicate the solution domain, is proposed for two-dimensional viscous uncompressed Navier-Stokes equation. Besides fewer pending unknowns, higher accuracy, and computation efficiency, it possesses such advantages as accurate representation of isogeometric analysis for object boundary and the unity of geometry and analysis modeling. Meanwhile, the selection of B-spline basis functions and the grid definition is studied and a stable discretization format satisfying inf-sup conditions is proposed. The degree of spline functions approaching the velocity field is one order higher than that approaching pressure field, and these functions are defined on one-time refined grid. The Dirichlet boundary conditions are imposed through the Nitsche variational principle in weak form due to the lack of interpolation properties of the B-splines functions. Finally, the validity of the proposed method is verified with some examples.
Two dimensional finite element thermal model of laser surface glazing for H13 tool steel
Kabir, I. R.; Yin, D.; Naher, S.
2016-10-01
A two dimensional (2D) transient thermal model with line-heat-source was developed by Finite Element Method (FEM) for laser surface glazing of H13 tool steel using commercial software-ANSYS 15. The geometry of the model was taken as a transverse circular cross-section of cylindrical specimen. Two different power levels (300W, 200W) were used with 0.2mm width of laser beam and 0.15ms exposure time. Temperature distribution, heating and cooling rates, and the dimensions of modified surface were analysed. The maximum temperatures achieved were 2532K (2259°C) and 1592K (1319°C) for laser power 300W and 200W respectively. The maximum cooling rates were 4.2×107 K/s for 300W and 2×107 K/s for 200W. Depths of modified zone increased with increasing laser power. From this analysis, it can be predicted that for 0.2mm beam width and 0.15ms time exposer melting temperature of H13 tool steel is achieved within 200-300W power range of laser beam in laser surface glazing.
Two Dimensional Finite Element Model to Study Calcium Distribution in Oocytes
Naik, Parvaiz Ahmad; Pardasani, Kamal Raj
2015-06-01
Cytosolic free calcium concentration is a key regulatory factor and perhaps the most widely used means of controlling cellular function. Calcium can enter cells through different pathways which are activated by specific stimuli including membrane depolarization, chemical signals and calcium depletion of intracellular stores. One of the important components of oocyte maturation is differentiation of the Ca2+ signaling machinery which is essential for egg activation after fertilization. Eggs acquire the ability to produce the fertilization-specific calcium signal during oocyte maturation. The calcium concentration patterns required during different stages of oocyte maturation are still not completely known. Also the mechanisms involved in calcium dynamics in oocyte cell are still not well understood. In view of above a two dimensional FEM model has been proposed to study calcium distribution in an oocyte cell. The parameters such as buffers, ryanodine receptor, SERCA pump and voltage gated calcium channel are incorporated in the model. Based on the biophysical conditions the initial and boundary conditions have been framed. The model is transformed into variational form and Ritz finite element method has been employed to obtain the solution. A program has been developed in MATLAB 7.10 for the entire problem and executed to obtain numerical results. The numerical results have been used to study the effect of buffers, RyR, SERCA pump and VGCC on calcium distribution in an oocyte cell.
A unidirectional approach for d-dimensional finite element methods for higher order on sparse grids
Bungartz, H.J. [Technische Universitaet Muenchen (Germany)
1996-12-31
In the last years, sparse grids have turned out to be a very interesting approach for the efficient iterative numerical solution of elliptic boundary value problems. In comparison to standard (full grid) discretization schemes, the number of grid points can be reduced significantly from O(N{sup d}) to O(N(log{sub 2}(N)){sup d-1}) in the d-dimensional case, whereas the accuracy of the approximation to the finite element solution is only slightly deteriorated: For piecewise d-linear basis functions, e. g., an accuracy of the order O(N{sup - 2}(log{sub 2}(N)){sup d-1}) with respect to the L{sub 2}-norm and of the order O(N{sup -1}) with respect to the energy norm has been shown. Furthermore, regular sparse grids can be extended in a very simple and natural manner to adaptive ones, which makes the hierarchical sparse grid concept applicable to problems that require adaptive grid refinement, too. An approach is presented for the Laplacian on a uinit domain in this paper.
Robol, Valentina; Grassi, Massimo; Casco, Clara
2013-08-09
Both neurophysiological and psychophysical evidence suggest a strong influence of context on texture-segmentation. Here we extend and further analyse this issue, with a particular focus on the underlying mechanism. Specifically, we use a texture-edge discrimination task and separately investigate the effect of elements far from and along the edge. Consistent with previous studies, we report both an iso-near contextual effect - whereby performance is better if elements along the edge are iso-oriented compared to ortho-oriented to the edge - as well as an ortho-far effect - whereby discrimination is higher when elements far from the edge are orthogonal to the edge. We found that backward mask, which is known to interrupt re-entrant processing from extrastriate areas, only interferes with the iso-near effect whereas perturbing orientation, position or contrast polarity of elements far from the edge only abolishes the ortho-far effect. This suggests that feedback processes may be involved in the iso-near effect. Instead, the ortho-far effect may be accounted for by recurrent interactions among 1st order filters. Copyright © 2013 Elsevier Ltd. All rights reserved.
Russell, Scott D; Gou, Xiaoping; Wong, Chui E; Wang, Xinkun; Yuan, Tong; Wei, Xiaoping; Bhalla, Prem L; Singh, Mohan B
2012-08-01
Genomic assay of sperm cell RNA provides insight into functional control, modes of regulation, and contributions of male gametes to double fertilization. Sperm cells of rice (Oryza sativa) were isolated from field-grown, disease-free plants and RNA was processed for use with the full-genome Affymetrix microarray. Comparison with Gene Expression Omnibus (GEO) reference arrays confirmed expressionally distinct gene profiles. A total of 10,732 distinct gene sequences were detected in sperm cells, of which 1668 were not expressed in pollen or seedlings. Pathways enriched in male germ cells included ubiquitin-mediated pathways, pathways involved in chromatin modeling including histones, histone modification and nonhistone epigenetic modification, and pathways related to RNAi and gene silencing. Genome-wide expression patterns in angiosperm sperm cells indicate common and divergent themes in the male germline that appear to be largely self-regulating through highly up-regulated chromatin modification pathways. A core of highly conserved genes appear common to all sperm cells, but evidence is still emerging that another class of genes have diverged in expression between monocots and dicots since their divergence. Sperm cell transcripts present at fusion may be transmitted through plasmogamy during double fertilization to effect immediate post-fertilization expression of early embryo and (or) endosperm development. © 2012 The Authors. New Phytologist © 2012 New Phytologist Trust.
Yoav Hadas
Full Text Available Cell fate commitment of spinal progenitor neurons is initiated by long-range, midline-derived, morphogens that regulate an array of transcription factors that, in turn, act sequentially or in parallel to control neuronal differentiation. Included among these are transcription factors that regulate the expression of receptors for guidance cues, thereby determining axonal trajectories. The Ig/FNIII superfamily molecules TAG1/Axonin1/CNTN2 (TAG1 and Neurofascin (Nfasc are co-expressed in numerous neuronal cell types in the CNS and PNS - for example motor, DRG and interneurons - both promote neurite outgrowth and both are required for the architecture and function of nodes of Ranvier. The genes encoding TAG1 and Nfasc are adjacent in the genome, an arrangement which is evolutionarily conserved. To study the transcriptional network that governs TAG1 and Nfasc expression in spinal motor and commissural neurons, we set out to identify cis elements that regulate their expression. Two evolutionarily conserved DNA modules, one located between the Nfasc and TAG1 genes and the second directly 5' to the first exon and encompassing the first intron of TAG1, were identified that direct complementary expression to the CNS and PNS, respectively, of the embryonic hindbrain and spinal cord. Sequential deletions and point mutations of the CNS enhancer element revealed a 130bp element containing three conserved E-boxes required for motor neuron expression. In combination, these two elements appear to recapitulate a major part of the pattern of TAG1 expression in the embryonic nervous system.
Cho, Sung-Yong; Huh, Yun-Hyuk; Park, Chan-Jin; Cho, Lee-Ra
To investigate the stress distribution in an implant-abutment complex with a preloaded abutment screw by comparing implant-abutment engagement features using three-dimensional finite element analysis (FEA). For FEA modeling, two implants-one with a single (S) engagement system and the other with a double (D) engagement system-were placed in the human mandibular molar region. Two types of abutments (hexagonal, conical) were connected to the implants. Different implant models (a single implant, two parallel implants, and mesial and tilted distal implants with 1-mm bone loss) were assumed. A static axial force and a 45-degree oblique force of 200 N were applied as the sum of vectors to the top of the prosthetic occlusal surface with a preload of 30 Ncm in the abutment screw. The von Mises stresses at the implant-abutment and abutment-screw interfaces were measured. In the single implant model, the S-conical abutment type exhibited broader stress distribution than the S-hexagonal abutment. In the double engagement system, the stress concentration was high in the lower contact area of the implant-abutment engagement. In the tilted implant model, the stress concentration point was different from that in the parallel implant model because of the difference in the bone level. The double engagement system demonstrated a high stress concentration at the lower contact area of the implant-abutment interface. To decrease the stress concentration, the type of engagement features of the implant-abutment connection should be carefully considered.
Yokoi, T [Building Research Institute, Tokyo (Japan); Sanchez-Sesma, F [Universidad National Autonoma de Mexico, (Mexico). Institute de Ingenieria
1997-05-27
Formulation is introduced for discretizing a boundary integral equation into an indirect boundary element method for the solution of 3-dimensional topographic problems. Yokoi and Takenaka propose an analytical solution-capable reference solution (solution for the half space elastic body with flat free surface) to problems of topographic response to seismic motion in a 2-dimensional in-plane field. That is to say, they propose a boundary integral equation capable of effectively suppressing the non-physical waves that emerge in the result of computation in the wake of the truncation of the discretized ground surface making use of the wave field in a semi-infinite elastic body with flat free surface. They apply the proposed boundary integral equation discretized into the indirect boundary element method to solve some examples, and succeed in proving its validity. In this report, the equation is expanded to deal with 3-dimensional topographic problems. A problem of a P-wave vertically landing on a flat and free surface is solved by the conventional boundary integral equation and the proposed boundary integral equation, and the solutions are compared with each other. It is found that the new method, different from the conventional one, can delete non-physical waves from the analytical result. 4 figs.
Yi, Longtao; Qin, Min; Wang, Kai; Peng, Shiqi; Sun, Tianxi; Liu, Zhiguo [Beijing Normal University, College of Nuclear Science and Technology, Beijing (China); Lin, Xue [Northwest University, School of Cultural Heritage, Xi' an (China)
2016-09-15
Confocal three-dimensional micro-X-ray fluorescence (3D-XRF) is a good surface analysis technology widely used to analyse elements and elemental distributions. However, it has rarely been applied to analyse surface topography and 3D elemental mapping in surface morphology. In this study, a surface adaptive algorithm using the progressive approximation method was designed to obtain surface topography. A series of 3D elemental mapping analyses in surface morphology were performed in laboratories to analyse painted pottery fragments from the Majiayao Culture (3300-2900 BC). To the best of our knowledge, for the first time, sample surface topography and 3D elemental mapping were simultaneously obtained. Besides, component and depth analyses were also performed using synchrotron radiation confocal 3D-XRF and tabletop confocal 3D-XRF, respectively. The depth profiles showed that the sample has a layered structure. The 3D elemental mapping showed that the red pigment, black pigment, and pottery coat contain a large amount of Fe, Mn, and Ca, respectively. From the 3D elemental mapping analyses at different depths, a 3D rendering was obtained, clearly showing the 3D distributions of the red pigment, black pigment, and pottery coat. Compared with conventional 3D scanning, this method is time-efficient for analysing 3D elemental distributions and hence especially suitable for samples with non-flat surfaces. (orig.)
Yi, Longtao; Qin, Min; Wang, Kai; Peng, Shiqi; Sun, Tianxi; Liu, Zhiguo; Lin, Xue
2016-01-01
Confocal three-dimensional micro-X-ray fluorescence (3D-XRF) is a good surface analysis technology widely used to analyse elements and elemental distributions. However, it has rarely been applied to analyse surface topography and 3D elemental mapping in surface morphology. In this study, a surface adaptive algorithm using the progressive approximation method was designed to obtain surface topography. A series of 3D elemental mapping analyses in surface morphology were performed in laboratories to analyse painted pottery fragments from the Majiayao Culture (3300-2900 BC). To the best of our knowledge, for the first time, sample surface topography and 3D elemental mapping were simultaneously obtained. Besides, component and depth analyses were also performed using synchrotron radiation confocal 3D-XRF and tabletop confocal 3D-XRF, respectively. The depth profiles showed that the sample has a layered structure. The 3D elemental mapping showed that the red pigment, black pigment, and pottery coat contain a large amount of Fe, Mn, and Ca, respectively. From the 3D elemental mapping analyses at different depths, a 3D rendering was obtained, clearly showing the 3D distributions of the red pigment, black pigment, and pottery coat. Compared with conventional 3D scanning, this method is time-efficient for analysing 3D elemental distributions and hence especially suitable for samples with non-flat surfaces. (orig.)
Summary of three-dimensional animation creation based on ethnic culture element
Shao Zhaopo
2016-01-01
Full Text Available three-dimensional animation is a product combined by technology and art. It is an artistic ex-pression form combining painting, film & television, digital technology, music, and literature. As an audio and visual art, three-dimensional animation has its own unique culture-loading function, technical aesthetic charac-teristics, and requirements for national art expression. This paper aims to find the method to combine digital technology and national art in combination of three-dimensional animation short film creation, and hopes to clear the road for the cultivation of domestic three-dimensional animation quality project.
Witt, R.J.
1989-01-01
Toroidal field (TF) coils in fusion systems are routinely operated at very high magnetic fields. While obtaining the response of the coil to in-plane loads is relatively straightforward, the same is not true for the out-of-plane loads. Previous treatments of the out-of-plane problem have involved large, three-dimensional finite element idealizations. A new treatment of the out-of-plane problem is presented here; the model is two-dimensional in nature, and consumes far less CPU-time than three-dimensional methods. The approach assumes there exists a region of torsional deformation in the inboard leg and a bending region in the outboard leg. It also assumes the outboard part of the coil is attached to a torque frame/cylinder, which experiences primarily torsional deformation. Three-dimensional transition regions exist between the inboard and outboard legs and between the outboard leg and the torque frame. By considering several idealized problems of cylindrical shells subjected to moment distributions, it is shown that the size of these three-dimensional regions is quite small, and that the interaction between the torsional and bending regions can be treated in an equivalent two-dimensional fashion. Equivalent stiffnesses are derived to model penetration into and twist along the cylinders. These stiffnesses are then used in a special substructuring analysis to couple the three regions together. Results from the new method are compared to results from a 3D continuum model. (orig.)
Hano, Mitsuo; Hotta, Masashi
A new multigrid method based on high-order vector finite elements is proposed in this paper. Low level discretizations in this method are obtained by using low-order vector finite elements for the same mesh. Gauss-Seidel method is used as a smoother, and a linear equation of lowest level is solved by ICCG method. But it is often found that multigrid solutions do not converge into ICCG solutions. An elimination algolithm of constant term using a null space of the coefficient matrix is also described. In three dimensional magnetostatic field analysis, convergence time and number of iteration of this multigrid method are discussed with the convectional ICCG method.
Franke, H.P.
1976-05-01
The finite element method is applied to the solution of the stationary 3D group diffusion equations. For this, a programme system with the name of FEM3D is established which also includes a module for semi-automatic mesh generation. Tetrahedral finite elements are used. The neutron fluxes are described by complete first- or second-order Lagrangian polynomials. General homogeneous boundary conditions are allowed. The studies show that realistic three-dimensional problems can be solved at less expense by iterative methods, in particular so when especially adapted matrix handling and storage schemes are used efficiently. (orig./RW) [de
Král, Radomil; Náprstek, Jiří
2017-01-01
Roč. 113, November (2017), s. 54-75 ISSN 0965-9978 R&D Projects: GA ČR(CZ) GP14-34467P; GA ČR(CZ) GA15-01035S Institutional support: RVO:68378297 Keywords : Fokker-Planck equation * finite element method * simplex element * multi-dimensional problem * non-symmetric operator Subject RIV: JM - Building Engineering OBOR OECD: Mechanical engineering Impact factor: 3.000, year: 2016 https://www.sciencedirect.com/science/ article /pii/S0965997817301904
Guggenberger, Christoph; Wolz, Christiane; Morrissey, Julie A.; Heesemann, Jürgen
2012-01-01
Staphylococcus aureus is a pyogenic abscess-forming facultative pathogenic microorganism expressing a large set of virulence-associated factors. Among these, secreted proteins with binding capacity to plasma proteins (e.g. fibrinogen binding proteins Eap and Emp) and prothrombin activators such as Coagulase (Coa) and vWbp are involved in abscess formation. By using a three-dimensional collagen gel (3D-CoG) supplemented with fibrinogen (Fib) we studied the growth behavior of S. aureus strain Newman and a set of mutants as well as their interaction with mouse neutrophils by real-time confocal microscopy. In 3D-CoG/Fib, S. aureus forms microcolonies which are surrounded by an inner pseudocapsule and an extended outer dense microcolony-associated meshwork (MAM) containing fibrin. Coa is involved in formation of the pseudocapsule whereas MAM formation depends on vWbp. Moreover, agr-dependent dispersal of late stage microcolonies could be observed. Furthermore, we demonstrate that the pseudocapsule and the MAM act as mechanical barriers against neutrophils attracted to the microcolony. The thrombin inhibitor argatroban is able to prevent formation of both pseudocapsule and MAM and supports access of neutrophils to staphylococci. Taken together, this model can simulate specific stages of S. aureus abscess formation by temporal dissection of bacterial growth and recruitment of immune cells. It can complement established animal infection models in the development of new treatment options. PMID:22253592
Hatice Z Nenseth
Full Text Available Closely related transcription factors (TFs can bind to the same response elements (REs with similar affinities and activate transcription. However, it is unknown whether transcription is similarly orchestrated by different TFs bound at the same RE. Here we have compared the recovery half time (t1/2, binding site occupancy and the resulting temporal changes in transcription upon binding of two closely related steroid receptors, the androgen and glucocorticoid receptors (AR and GR, to their common hormone REs (HREs. We show that there are significant differences at all of these levels between AR and GR at the MMTV HRE when activated by their ligands. These data show that two TFs bound at the same RE can have significantly different modes of action that can affect their responses to environmental cues.
Chen, Yung-Chuan; Tu, Yuan-Kun; Zhuang, Jun-Yan; Tsai, Yi-Jung; Yen, Cheng-Yo; Hsiao, Chih-Kun
2017-11-01
A three-dimensional dynamic elastoplastic finite element model was constructed and experimentally validated and was used to investigate the parameters which influence bone temperature during drilling, including the drill speed, feeding force, drill bit diameter, and bone density. Results showed the proposed three-dimensional dynamic elastoplastic finite element model can effectively simulate the temperature elevation during bone drilling. The bone temperature rise decreased with an increase in feeding force and drill speed, however, increased with the diameter of drill bit or bone density. The temperature distribution is significantly affected by the drilling duration; a lower drilling speed reduced the exposure duration, decreases the region of the thermally affected zone. The constructed model could be applied for analyzing the influence parameters during bone drilling to reduce the risk of thermal necrosis. It may provide important information for the design of drill bits and surgical drilling powers.
El-Zein, Abbas; Carter, John P.; Airey, David W.
2006-06-01
A three-dimensional finite-element model of contaminant migration in fissured clays or contaminated sand which includes multiple sources of non-equilibrium processes is proposed. The conceptual framework can accommodate a regular network of fissures in 1D, 2D or 3D and immobile solutions in the macro-pores of aggregated topsoils, as well as non-equilibrium sorption. A Galerkin weighted-residual statement for the three-dimensional form of the equations in the Laplace domain is formulated. Equations are discretized using linear and quadratic prism elements. The system of algebraic equations is solved in the Laplace domain and solution is inverted to the time domain numerically. The model is validated and its scope is illustrated through the analysis of three problems: a waste repository deeply buried in fissured clay, a storage tank leaking into sand and a sanitary landfill leaching into fissured clay over a sand aquifer.
Lee, Chia-Fone; Chen, Peir-Rong; Lee, Wen-Jeng; Chen, Jyh-Horng; Liu, Tien-Chen
2006-05-01
To present a systematic and practical approach that uses high-resolution computed tomography to derive models of the middle ear for finite element analysis. This prospective study included 31 subjects with normal hearing and no previous otologic disorders. Temporal bone images obtained from 15 right ears and 16 left ears were used for evaluation and reconstruction. High-resolution computed tomography of temporal bone was performed using simultaneous acquisition of 16 sections with a collimated slice thickness of 0.625 mm. All images were transferred to an Amira visualization system for three-dimensional reconstruction. The created three-dimensional model was translated into two commercial modeling packages, Patran and ANSYS, for finite element analysis. The characteristic dimensions of the model were measured and compared with previously published histologic section data. This result confirms that the geometric model created by the proposed method is accurate except that the tympanic membrane is thicker than when measured by the histologic section method. No obvious difference in the geometrical dimension between right and left ossicles was found (P > .05). The three-dimensional model created by finite element method and predicted umbo and stapes displacements are close to the bounds of the experimental curves of Nishihara's, Huber's, Gan's, and Sun's data across the frequency range of 100 to 8000 Hz. The model includes a description of the geometry of the middle ear components and dynamic equations of vibration. The proposed method is quick, practical, low-cost, and, most importantly, noninvasive as compared with histologic section methods.
Osman, Reham B; Elkhadem, Amr H; Ma, Sunyoung; Swain, Michael V
2013-01-01
The purpose of this study was to compare the stress and strain occurring in peri-implant bone and implants used to support maxillary overdentures. Three-dimensional finite element analysis (3D FEA) was used to compare one-piece zirconia and titanium implants. Two types of implants were simulated using a 3D FEA model: one-piece zirconia and titanium implants (diameter, 3.8 × 11.5 mm) with 2.25-mm diameter ball abutments. In each simulation four implants were placed bilaterally in the canine/premolar region of an edentulous maxillary model. Static loads were applied axially and 20 degrees buccolingually on the buccal slope of the lingual cusps of posterior teeth of the first quadrant. Von Mises stresses and equivalent strains generated in peri-implant bone and first principal stresses in the implants were calculated. Comparable stress and strain values were shown in the peri-implant bone for both types of implants. The maximum equivalent strain produced in the peri-implant region was mostly within the range for bone augmentation. Under oblique loading, maximum von Mises stresses and equivalent strain were more evident at the neck of the most distal implant on the loaded side. Under axial load, the stress and strain were transferred to the peri-implant bone around the apex of the implant. Maximum tensile stresses that developed for either material were well below their fracture strength. The highest stresses were mainly located at the distobuccal region of the neck for the two implant materials under both loading conditions. From a biomechanical point of view, ceramic implants made from yttrium-stabilized tetragonal polycrystalline zirconia may be a potential alternative to conventional titanium implants for the support of overdentures. This is particularly relevant for a select group of patients with a proven allergy to titanium. Prospective clinical studies are still required to confirm these in vitro results. Different simulations presenting various cortical bone
Gibson-Reinemer, D. K.; Johnson, B.M.; Martinez, P.J.; Winkelman, D.L.; Koenig, A.E.; Woodhead, J.D.
2009-01-01
Otolith chemistry in freshwater has considerable potential to reveal patterns of origin and movement, which would benefit traditional fisheries management and provide a valuable tool to curb the spread of invasive and illicitly stocked species. We evaluated the relationship between otolith and water chemistry for five markers (Ba/Ca, Mn/Ca, Sr/ Ca, Zn/Ca, and 87Sr/86Sr) in rainbow trout (Oncorhynchus mykiss) using the existing hatchery system in Colorado and Wyoming, USA, to provide controlled, seminatural conditions. Otolith Ba/Ca, Sr/Ca, and 87Sr/86Sr reflected ambient levels, whereas Mn/Ca and Zn/Ca did not. Using only the markers correlated with water chemistry, we classified fish to their hatchery of origin with up to 96% accuracy when element and isotope data were used together. Large changes in 87Sr/Sr were evident in otolith transects, although subtler changes in Sr/Ca were also detectable. Our results suggest the relatively few otolith markers that reflect ambient chemistry can discriminate among locations and track movements well enough to provide valuable insight in a variety of applied contexts.
Stone, C.M.
1997-07-01
SANTOS is a finite element program designed to compute the quasistatic, large deformation, inelastic response of two-dimensional planar or axisymmetric solids. The code is derived from the transient dynamic code PRONTO 2D. The solution strategy used to compute the equilibrium states is based on a self-adaptive dynamic relaxation solution scheme, which is based on explicit central difference pseudo-time integration and artificial mass proportional damping. The element used in SANTOS is a uniform strain 4-node quadrilateral element with an hourglass control scheme to control the spurious deformation modes. Finite strain constitutive models for many common engineering materials are included. A robust master-slave contact algorithm for modeling sliding contact is implemented. An interface for coupling to an external code is also provided. 43 refs., 22 figs.
Young Soo Kim
2013-05-01
Full Text Available BackgroundTo construct a sophisticated three-dimensional framework, numerous modifications have been reported in the literature. However, most surgeons have paid little attention to the anatomical configuration of the concha and more to its deepness and hollowness, leading to unsatisfactory outcomes.MethodsFor a configuration of the concha that is definitely anatomical, the author further developed and employed the conchal bowl element, which has been used by several surgeons although the results have not been published elsewhere. The author constructed the conchal bowl element in one of three patterns according to the amount of available cartilages: one block, two-pieces, or a cymba bowl element only. A total of 20 patients underwent auricular reconstruction using a costal cartilage framework between 2009 and 2012. The 8 earliest reconstructions were performed without a conchal bowl element and the latter 12 with a conchal bowl element. The patients were followed up for more than 1 year. The aesthetic results were scored by evaluating characteristics involving the stability of the crus helicis, the conchal definition, and the smoothness of the helical curve.ResultsThe ears reconstructed early without a conchal bowl element showed a shallow and one or two incompletely separated concha with an obliterated cymba conchal space. They also did not have a realistic or smooth curve of the helix because of an unstable crus helicis. However, ears reconstructed later with the concha bowl element showed a definite crus helicis, deep cymba conchal space, and smooth helical curve.ConclusionsThe construction of the conchal bowl element is simple, not time-consuming procedure. It is suggested that the conchal bowl element must be constructed and attached to the main framework for natural configuration of the reconstructed ear.
Adaptive contact elements for three-dimensional fluid-structure interfaces
Kulak, R.F.
1985-01-01
A finite element method is developed for treating the mechanics of contact between two deformable bodies which occurs, for example, at fluid-structure interfaces. The method uses a family of adaptive contact elements, which are based upon the penalty method, to handle all of the possible contact configurations that can occur between the discretized contacting bodies. The contact element's nodal connectivity is allowed to change during the computations in order to accommodate finite sliding. The infusion of these elements in the interface results in satisfying the force equilibrium condition during contact. The methodology has been implemented into the NEPTUNE code. Results are presented for an illustrative problem
Adaptive contact elements for three-dimensional fluid-structure interfaces
Kulak, R.F.
1985-01-01
A finite element method is developed for treating the mechanics of contact between two deformable bodies which occurs, for example, at fluid-structure interfaces. The method uses a family of adaptive contact elements, which are based upon the penalty method, to handle all of the possible contact configurations that can occur between the discretized contacting bodies. The contact element's nodal connectivity is allowed to change during the computations in order to accommodate finite sliding. The infusion of these elements in the interface results in satisfying the force equilibrium condition during contact. The methodology has been implemented into the NEPTUNE code. Results are presented for an illustrative problem.
Kiyono, J.; Miura, F.; Takimoto, K. [Yamaguchi Univ., Yamaguchi (Japan). Faculty of Engineering
1996-04-21
In this study, the possibility to apply the Distinct Element Method (DEM) to human evacuation behavior during a disaster was investigated, evacuation from rooms to outside though a passage or steps and a jam were examined as a basic consideration. The main results were obtained as follows: according to an analysis of evacuation behavior when elements of DEM were substituted for individual humans, the trace of individual people and force acting there to and the trace of the whole group so every time can be understood, analysis can also be conducted from local to macro. In the DEM analysis, a mutual distance between people and characteristics of behavior can be expressed well by introducing an imaginary bane into the elements. Evacuation time due to change of space shape can be compared and time series change of force acting on individual people can be understood according to the investigation on evacuation time difference due to shape change at the exit and entrance and the jam caused by the arch effect happened when the crowed flow appeared at the exit and entrance. 16 refs., 21 figs., 4 tabs.
Multisymplectic Structure－Preserving in Simple Finite Element Method in High Dimensional Case
BAIYong-Qiang; LIUZhen; PEIMing; ZHENGZhu-Jun
2003-01-01
In this paper, we study a finite element scheme of some semi-linear elliptic boundary value problems in high-dhnensjonal space. With uniform mesh, we find that, the numerical scheme derived from finite element method can keep a preserved multisymplectic structure.
Chiba, Gou; Tsuji, Masashi; Shimazu, Yoichiro
2001-01-01
A hierarchical domain decomposition boundary element method (HDD-BEM) that was developed to solve a two-dimensional neutron diffusion equation has been modified to deal with three-dimensional problems. In the HDD-BEM, the domain is decomposed into homogeneous regions. The boundary conditions on the common inner boundaries between decomposed regions and the neutron multiplication factor are initially assumed. With these assumptions, the neutron diffusion equations defined in decomposed homogeneous regions can be solved respectively by applying the boundary element method. This part corresponds to the 'lower level' calculations. At the 'higher level' calculations, the assumed values, the inner boundary conditions and the neutron multiplication factor, are modified so as to satisfy the continuity conditions for the neutron flux and the neutron currents on the inner boundaries. These procedures of the lower and higher levels are executed alternately and iteratively until the continuity conditions are satisfied within a convergence tolerance. With the hierarchical domain decomposition, it is possible to deal with problems composing a large number of regions, something that has been difficult with the conventional BEM. In this paper, it is showed that a three-dimensional problem even with 722 regions can be solved with a fine accuracy and an acceptable computation time. (author)
Atluri, S. N.; Nakagaki, M.; Kathiresan, K.
1980-01-01
In this paper, efficient numerical methods for the analysis of crack-closure effects on fatigue-crack-growth-rates, in plane stress situations, and for the solution of stress-intensity factors for arbitrary shaped surface flaws in pressure vessels, are presented. For the former problem, an elastic-plastic finite element procedure valid for the case of finite deformation gradients is developed and crack growth is simulated by the translation of near-crack-tip elements with embedded plastic singularities. For the latter problem, an embedded-elastic-singularity hybrid finite element method, which leads to a direct evaluation of K-factors, is employed.
B. K. Shayakhmetov
2014-01-01
Full Text Available In the work there are presented the results of studying the filtering elements weight changes when heated. For all the variants of filtering elements at the primary stages of heating there is characteristic increasing their linear dimensions due to their thermal expansion. It was established that using hydrolyzed ethyl silicate as a binder, as well as water solution of liquid glass with addition of aluminum powder in the refractory material permits to obtain filtering elements without high-temperature solid-phase sintering.
3-dimensional finite element modelling of reactor building internal structure for static analysis
Joshi, M.H.; Reddy, V.J.; Kushwaha, H.S.; Reddy, G.R.; Karandikar, G.V.
1991-01-01
a) Thin shell element gives fairly accurate results when compared to 3-D Brick element for the type of structure and loading in Reactor Building. b) The maximum element size is fixed from model 3(c) i.e. 2.0 m. c) Openings with size smaller than 0.5 m can be neglected without affecting the results very much. d) For any such problem, the methodology described in this paper can be used to take rational decisions which will ensure reasonable accuracy. (author)
Fujimura, Toichiro
1996-01-01
A three-dimensional neutron transport code DFEM has been developed by the double finite element method to analyze reactor cores with complex geometry as large fast reactors. Solution algorithm is based on the double finite element method in which the space and angle finite elements are employed. A reactor core system can be divided into some triangular and/or quadrangular prism elements, and the spatial distribution of neutron flux in each element is approximated with linear basis functions. As for the angular variables, various basis functions are applied, and their characteristics were clarified by comparison. In order to enhance the accuracy, a general method is derived to remedy the truncation errors at reflective boundaries, which are inherent in the conventional FEM. An adaptive acceleration method and the source extrapolation method were applied to accelerate the convergence of the iterations. The code structure is outlined and explanations are given on how to prepare input data. A sample input list is shown for reference. The eigenvalue and flux distribution for real scale fast reactors and the NEA benchmark problems were presented and discussed in comparison with the results of other transport codes. (author)
Poropat, Stephen F.; Kear, Benjamin P.
2013-01-01
Background Euhelopus zdanskyi is one of relatively few sauropod taxa known from an almost complete skull and mandible. Recent phylogenetic analyses suggest that Euhelopus is a somphospondylan titanosauriform, and that it is a member of the clade (Euhelopodidae) which is the sister taxon to the hugely successful, dominantly Cretaceous sauropod group Titanosauria. Methodology/Principal Findings The skull elements of Euhelopus were CT scanned at Uppsala Akademiska Sjukhuset. Three-dimensional models of the elements were constructed from the DICOM data using Mimics 14.0, InVesalius 3.0, and GeoMagic Studio 2012, the skull was rearticulated in Rhinoceros 4.0, and the final version was rendered in GeoMagic Studio 2012. Conclusions/Significance The fact that relatively complete sauropod skulls are so rare in the fossil record, particularly among titanosauriforms, means that the skulls that are known should be as thoroughly described and well-illustrated as possible. This contribution supplements previous descriptions of the cranial elements of Euhelopus, one of the few euhelopodid taxa for which cranial material is known, by presenting a comprehensive photographic atlas of the skull elements to facilitate a better understanding of their morphology. We describe several elements which have been overlooked in past studies of Euhelopus, and also provide as accurate a reconstruction of the skull as possible (in the absence of the braincase), the most significant components of which are the articulations of the palate and the mandible. PMID:24278222
Finite element formulation for fluid-structure interaction in three-dimensional space
Kulak, R.F.
1979-01-01
A development is presented for a three-dimension hexahedral hydrodynamic finite-element. Using trilinear shape functions and assuming a constant pressure field in each element, simple relations were obtained for internal nodal forces. Because the formulation was based upon a rate approach it was applicable to problems involving large displacements. This element was incorporated into an existing plate-shell finite element code. Diagonal mass matrices were used and the resulting discrete equations of motion were solved using explicit temporal integrator. Results for several problems were presented which compare numerical predictions to closed form analytical solutions. In addition, the fluid-structure interaction problem of a fluid-filled, cylindrical vessel containing internal cylinders was studied. The internal cylinders were cantilever supported from the top cover of the vessel and were periodically located circumferentially at a fixed radius. A pressurized cylindrical cavity located at the bottom of the vessel at its centerline provided the loading
Park, Jai Hak; Nikishkov, G. P.
2010-01-01
An SGBEM (symmetric Galerkin boundary element method)-FEM alternating method has been proposed by Nikishkov, Park and Atluri. This method can be used to obtain mixed-mode stress intensity factors for planar and nonplanar three-dimensional cracks having an arbitrary shape. For field applications, however, it is necessary to verify the accuracy and consistency of this method. Therefore, in this study, we investigate the effects of several factors on the accuracy of the stress intensity factors obtained using the above mentioned alternating method. The obtained stress intensity factors are compared with the known values provided in handbooks, especially in the case of internal and external circumferential semi-elliptical surface cracks. The results show that the SGBEM-FEM alternating method yields accurate stress intensity factors for three-dimensional cracks, including internal and external circumferential surface cracks and that the method can be used as a robust crack analysis tool for solving field problems
Itagaki, Masafumi; Sahashi, Naoki.
1997-01-01
The multiple reciprocity boundary element method has been applied to three-dimensional two-group neutron diffusion problems. A matrix-type boundary integral equation has been derived to solve the first and the second group neutron diffusion equations simultaneously. The matrix-type fundamental solutions used here satisfy the equation which has a point source term and is adjoint to the neutron diffusion equations. A multiple reciprocity method has been employed to transform the matrix-type domain integral related to the fission source into an equivalent boundary one. The higher order fundamental solutions required for this formulation are composed of a series of two types of analytic functions. The eigenvalue itself is also calculated using only boundary integrals. Three-dimensional test calculations indicate that the present method provides stable and accurate solutions for criticality problems. (author)
Smith Nadine
2005-06-01
Full Text Available Abstract Background Prostate cancer and benign prostatic hyperplasia are very common diseases in older American men, thus having a reliable treatment modality for both diseases is of great importance. The currently used treating options, mainly surgical ones, have numerous complications, which include the many side effects that accompany such procedures, besides the invasive nature of such techniques. Focused ultrasound is a relatively new treating modality that is showing promising results in treating prostate cancer and benign prostatic hyperplasia. Thus this technique is gaining more attention in the past decade as a non-invasive method to treat both diseases. Methods In this paper, the design, construction and evaluation of a 1.75 dimensional ultrasound phased array to be used for treating prostate cancer and benign prostatic hyperplasia is presented. With this array, the position of the focus can be controlled by changing the electrical power and phase to the individual elements for electronically focusing and steering in a three dimensional volume. The array was designed with a maximum steering angle of ± 13.5° in the transverse direction and a maximum depth of penetration of 11 cm, which allows the treatment of large prostates. The transducer piezoelectric ceramic, matching layers and cable impedance have been designed for maximum power transfer to tissue. Results To verify the capability of the transducer for focusing and steering, exposimetry was performed and the results correlated well with the calculated field. Ex vivo experiments using bovine tissue were performed with various lesion sizes and indicated the capability of the transducer to ablate tissue using short sonications. Conclusion A 1.75 dimensional array, that overcame the drawbacks associated with one-dimensional arrays, has been designed, built and successfully tested. Design issues, such as cable and ceramic capacitances, were taken into account when designing this
Three-dimensional reconstruction of indoor whole elements based on mobile LiDAR point cloud data
Gong, Yuejian; Mao, Wenbo; Bi, Jiantao; Ji, Wei; He, Zhanjun
2014-11-01
Ground-based LiDAR is one of the most effective city modeling tools at present, which has been widely used for three-dimensional reconstruction of outdoor objects. However, as for indoor objects, there are some technical bottlenecks due to lack of GPS signal. In this paper, based on the high-precision indoor point cloud data which was obtained by LiDAR, an international advanced indoor mobile measuring equipment, high -precision model was fulfilled for all indoor ancillary facilities. The point cloud data we employed also contain color feature, which is extracted by fusion with CCD images. Thus, it has both space geometric feature and spectral information which can be used for constructing objects' surface and restoring color and texture of the geometric model. Based on Autodesk CAD platform and with help of PointSence plug, three-dimensional reconstruction of indoor whole elements was realized. Specifically, Pointools Edit Pro was adopted to edit the point cloud, then different types of indoor point cloud data was processed, including data format conversion, outline extracting and texture mapping of the point cloud model. Finally, three-dimensional visualization of the real-world indoor was completed. Experiment results showed that high-precision 3D point cloud data obtained by indoor mobile measuring equipment can be used for indoor whole elements' 3-d reconstruction and that methods proposed in this paper can efficiently realize the 3 -d construction of indoor whole elements. Moreover, the modeling precision could be controlled within 5 cm, which was proved to be a satisfactory result.
Rudianto, Indra; Sudarmaji
2018-04-01
We present an implementation of the spectral-element method for simulation of two-dimensional elastic wave propagation in fully heterogeneous media. We have incorporated most of realistic geological features in the model, including surface topography, curved layer interfaces, and 2-D wave-speed heterogeneity. To accommodate such complexity, we use an unstructured quadrilateral meshing technique. Simulation was performed on a GPU cluster, which consists of 24 core processors Intel Xeon CPU and 4 NVIDIA Quadro graphics cards using CUDA and MPI implementation. We speed up the computation by a factor of about 5 compared to MPI only, and by a factor of about 40 compared to Serial implementation.
Hrehor, M.
1979-01-01
The paper deals with an application of the finite element method to the heat transfer study in seven-pin models of LMFBR fuel subassembly. The developed code NCEL solves two-dimensional steady state heat conduction equation in the whole subassembly model cross-section and enebles to perform the analysis of thermal behaviour in both normal and accidental operational conditions as eccentricity of the central rod or full or partial (porous) blockage of some part of the cross-flow area. The heat removal is simulated by heat sinks in coolant under conditions of subchannels slug flow approximation
Three-dimensional Finite Elements Method simulation of Total Ionizing Dose in 22 nm bulk nFinFETs
Chatzikyriakou, Eleni, E-mail: ec3g12@soton.ac.uk; Potter, Kenneth; Redman-White, William; De Groot, C.H.
2017-02-15
Highlights: • Simulation of Total Ionizing Dose using the Finite Elements Method. • Carrier generation, transport and trapping in the oxide. • Application in three-dimensional bulk FinFET model of 22 nm node. • Examination of trapped charge in the Shallow Trench Isolation. • Trapped charge dependency of parasitic transistor current. - Abstract: Finite Elements Method simulation of Total Ionizing Dose effects on 22 nm bulk Fin Field Effect Transistor (FinFET) devices using the commercial software Synopsys Sentaurus TCAD is presented. The simulation parameters are extracted by calibrating the charge trapping model to experimental results on 400 nm SiO{sub 2} capacitors irradiated under zero bias. The FinFET device characteristics are calibrated to the Intel 22 nm bulk technology. Irradiation simulations of the transistor performed with all terminals unbiased reveal increased hardness up to a total dose of 1 MRad(SiO{sub 2}).
Guo, Guifang; Long, Bo; Cheng, Bo; Zhou, Shiqiong; Xu, Peng; Cao, Binggang
In order to better understand the thermal abuse behavior of high capacities and large power lithium-ion batteries for electric vehicle application, a three-dimensional thermal model has been developed for analyzing the temperature distribution under abuse conditions. The model takes into account the effects of heat generation, internal conduction and convection, and external heat dissipation to predict the temperature distribution in a battery. Three-dimensional model also considers the geometrical features to simulate oven test, which are significant in larger cells for electric vehicle application. The model predictions are compared to oven test results for VLP 50/62/100S-Fe (3.2 V/55 Ah) LiFePO 4/graphite cells and shown to be in great agreement.
Shen, Wei; Li, Dongsheng; Zhang, Shuaifang; Ou, Jinping
2017-07-01
This paper presents a hybrid method that combines the B-spline wavelet on the interval (BSWI) finite element method and spectral analysis based on fast Fourier transform (FFT) to study wave propagation in One-Dimensional (1D) structures. BSWI scaling functions are utilized to approximate the theoretical wave solution in the spatial domain and construct a high-accuracy dynamic stiffness matrix. Dynamic reduction on element level is applied to eliminate the interior degrees of freedom of BSWI elements and substantially reduce the size of the system matrix. The dynamic equations of the system are then transformed and solved in the frequency domain through FFT-based spectral analysis which is especially suitable for parallel computation. A comparative analysis of four different finite element methods is conducted to demonstrate the validity and efficiency of the proposed method when utilized in high-frequency wave problems. Other numerical examples are utilized to simulate the influence of crack and delamination on wave propagation in 1D rods and beams. Finally, the errors caused by FFT and their corresponding solutions are presented.
Hong, Z; Jiang, Y; Pei, R; Coombs, T A [Electronic, Power and Energy Conversion Group, Engineering Department, University of Cambridge, CB2 1PZ (United Kingdom); Ye, L [Department of Electrical Power Engineering, CAU, P. O. Box 210, Beijing 100083 (China); Campbell, A M [Interdisciplinary Research Centre in Superconductivity, University of Cambridge, CB3 0HE (United Kingdom)], E-mail: Zh223@cam.ac.uk
2008-02-15
In order to utilize HTS conductors in AC electrical devices, it is very important to be able to understand the characteristics of HTS materials in the AC electromagnetic conditions and give an accurate estimate of the AC loss. A numerical method is proposed in this paper to estimate the AC loss in superconducting conductors including MgB{sub 2} wires and YBCO coated conductors. This method is based on solving a set of partial differential equations in which the magnetic field is used as the state variable to get the current and electric field distributions in the cross sections of the conductors and hence the AC loss can be calculated. This method is used to model a single-element and a multi-element MgB{sub 2} wires. The results demonstrate that the multi-element MgB{sub 2} wire has a lower AC loss than a single-element one when carrying the same current. The model is also used to simulate YBCO coated conductors by simplifying the superconducting thin tape into a one-dimensional region where the thickness of the coated conductor can be ignored. The results show a good agreement with the measurement.
Kurt, Melike; Moored, Keith
2018-04-19
-dimensions. These results can aid in the design of networked bio-inspired control elements that through integrated sensing can synchronize to three-dimensional flow interactions. © 2018 IOP Publishing Ltd.
Correlation between eigenvalues and sorted diagonal matrix elements of a large dimensional matrix
Arima, A.
2008-01-01
Functional dependences of eigenvalues as functions of sorted diagonal elements are given for realistic nuclear shell model (NSM) hamiltonian, the uniform distribution hamiltonian and the GOE hamiltonian. In the NSM case, the dependence is found to be linear. We discuss extrapolation methods for more accurate predictions for low-lying states. (author)
Conci, Ricardo Augusto; Tomazi, Flavio Henrique Silveira; Noritomi, Pedro Yoshito; da Silva, Jorge Vicente Lopes; Fritscher, Guilherme Genehr; Heitz, Claiton
2015-07-01
To compare the mechanical stress on the mandibular condyle after the reduction and fixation of mandibular condylar fractures using the neck screw and 2 other conventional techniques according to 3-dimensional finite element analysis. A 3-dimensional finite element model of a mandible was created and graphically simulated on a computer screen. The model was fixed with 3 different techniques: a 2.0-mm plate with 4 screws, 2 plates (1 1.5-mm plate and 1 2.0-mm plate) with 4 screws, and a neck screw. Loads were applied that simulated muscular action, with restrictions of the upper movements of the mandible, differentiation of the cortical and medullary bone, and the virtual "folds" of the plates and screws so that they could adjust to the condylar surface. Afterward, the data were exported for graphic visualization of the results and quantitative analysis was performed. The 2-plate technique exhibited better stability in regard to displacement of fractures, deformity of the synthesis materials, and minimum and maximum tension values. The results with the neck screw were satisfactory and were similar to those found when a miniplate was used. Although the study shows that 2 isolated plates yielded better results compared with the other groups using other fixation systems and methods, the neck screw could be an option for condylar fracture reduction. Copyright © 2015 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.
Gupta, S.K.; Cole, C.R.; Bond, F.W.
1979-12-01
The Assessment of Effectiveness of Geologic Isolation Systems (AEGIS) Program is developing and applying the methodology for assessing the far-field, long-term post-closure safety of deep geologic nuclear waste repositories. AEGIS is being performed by Pacific Northwest Laboratory (PNL) under contract with the Office of Nuclear Waste Isolation (OWNI) for the Department of Energy (DOE). One task within AEGIS is the development of methodology for analysis of the consequences (water pathway) from loss of repository containment as defined by various release scenarios. Analysis of the long-term, far-field consequences of release scenarios requires the application of numerical codes which simulate the hydrologic systems, model the transport of released radionuclides through the hydrologic systems to the biosphere, and, where applicable, assess the radiological dose to humans. Hydrologic and transport models are available at several levels of complexity or sophistication. Model selection and use are determined by the quantity and quality of input data. Model development under AEGIS and related programs provides three levels of hydrologic models, two levels of transport models, and one level of dose models (with several separate models). This document consists of the description of the FE3DGW (Finite Element, Three-Dimensional Groundwater) Hydrologic model third level (high complexity) three-dimensional, finite element approach (Galerkin formulation) for saturated groundwater flow
Nissen, K.L.
1988-06-01
Two computer codes for the analysis of fuel rod behavior have been developed. Fuel rod mechanics is treated by a two-dimensional, axisymmetric finite element method. The program KONTAKT is used for detailed examinations on fuel rod sections, whereas the second program METHOD2D allows instationary calculations of whole fuel rods. The mechanical contact of fuel and cladding during heating of the fuel rod is very important for it's integrity. Both computer codes use a Newton-Raphson iteration for the solution of the nonlinear solid body contact problem. A constitutive equation is applied for the dependency of contact pressure on normal approach of the surfaces which are assumed to be rough. If friction is present on the contacting surfaces, Coulomb's friction law is used. Code validation is done by comparison with known analytical solutions for special problems. Results of the contact algorithm for an elastic ball pressing against a rigid surface are confronted with Hertzian theory. Influences of fuel-pellet geometry as well as influences of discretisation of displacements and stresses of a single fuel pellet are studied. Contact of fuel and cladding is calculated for a fuel rod section with two fuel pellets. The influence of friction forces between fuel and cladding on their axial expansion is demonstrated. By calculation of deformations and temperatures during an instationary fuel rod experiment of the CABRI-series the feasibility of two-dimensional finite element analysis of whole fuel rods is shown. (orig.) [de
Arunachalam Sangeetha
2012-01-01
Full Text Available Context: To understand the effect of masticatory and parafunctional forces on the integrity of the prosthesis and the underlying cement layer. Aims: The purpose of this study was to evaluate the stress pattern in the cement layer and the fixed prosthesis, on subjecting a three-dimensional finite element model to simulated occlusal loading. Materials and Methods: Three-dimensional finite element model was simulated to replace missing mandibular first molar with second premolar and second molar as abutments. The model was subjected to a range of occlusal loads (20, 30, 40 MPa in two different directions - vertical and 30° to the vertical. The cements (zinc phosphate, polycarboxylate, glass ionomer, and composite were modeled with two cement thicknesses - 25 and 100 μm. Stresses were determined in certain reference points in fixed prosthesis and the cement layer. Statistical Analysis Used: The stress values are mathematic calculations without variance; hence, statistical analysis is not routinely required. Results: Stress levels were calculated according to Von Mises criteria for each node. Maximum stresses were recorded at the occlusal surface, axio-gingival corners, followed by axial wall. The stresses were greater with lateral load and with 100-μm cement thickness. Results revealed higher stresses for zinc phosphate cement, followed by composites. Conclusions: The thinner cement interfaces favor the success of the prosthesis. The stresses in the prosthesis suggest rounding of axio-gingival corners and a well-established finish line as important factors in maintaining the integrity of the prosthesis.
A three-dimensional spectral element model for the solution of the hydrostatic primitive equations
Iskandarani, M; Levin, J C
2003-01-01
We present a spectral element model to solve the hydrostatic primitive equations governing large-scale geophysical flows. The highlights of this new model include unstructured grids, dual h-p paths to convergence, and good scalability characteristics on present day parallel computers including Beowulf-class systems. The behavior of the model is assessed on three process-oriented test problems involving wave propagation, gravitational adjustment, and nonlinear flow rectification, respectively. The first of these test problems is a study of the convergence properties of the model when simulating the linear propagation of baroclinic Kelvin waves. The second is an intercomparison of spectral element and finite-difference model solutions to the adjustment of a density front in a straight channel. Finally, the third problem considers the comparison of model results to measurements obtained from a laboratory simulation of flow around a submarine canyon. The aforementioned tests demonstrate the good performance of th...
Three-dimensionality of space in the structure of the periodic table of chemical elements
Veremeichik, T. F.
2006-01-01
The effect of the dimension of the 3D homogeneous and isotropic Euclidean space, and the electron spin on the self-organization of the electron systems of atoms of chemical elements is considered. It is shown that the finite dimension of space creates the possibility of periodicity in the structure of an electron cloud, while the value of the dimension determines the number of stable systems of electrons at different levels of the periodic table of chemical elements and some characteristics of the systems. The conditions for the stability of systems of electrons and the electron system of an atom as a whole are considered. On the basis of the results obtained, comparison with other hierarchical systems (nanostructures and biological structures) is performed
Two-dimensional multigroup finite element calculation of fast reactor in diffusion approximation
Schmid, J.
1986-06-01
When a linear element of triangular shape is used the actual finite element calculation is relatively simple. Extensive programs for mesh generation were written for easy inputting the configuration of reactors. A number of other programs were written for plotting neutron flux fields in individual groups, the power distribution, spatial plotting of fields, etc. The operation of selected programs, data preparation and operating instructions are described and examples given of data and results. All programs are written in GIER ALGOL. The used method and the developed programs have demonstrated that they are a useful instrument for the calculation of criticality and the distribution of neutron flux and power of both fast and thermal reactors. (J.B.)
Three-dimensional Finite Element Modelling of Composite Slabs for High Speed Rails
Mlilo, Nhlanganiso; Kaewunruen, Sakdirat
2017-12-01
Currently precast steel-concrete composite slabs are being considered on railway bridges as a viable alternative replacement for timber sleepers. However, due to their nature and the loading conditions, their behaviour is often complex. Present knowledge of the behaviour of precast steel-concrete composite slabs subjected to rail loading is limited. FEA is an important tool used to simulate real life behaviour and is widely accepted in many disciples of engineering as an alternative to experimental test methods, which are often costly and time consuming. This paper seeks to detail FEM of precast steel-concrete slabs subjected to standard in-service loading in high-speed rail with focus on the importance of accurately defining material properties, element type, mesh size, contacts, interactions and boundary conditions that will give results representative of real life behaviour. Initial finite element model show very good results, confirming the accuracy of the modelling procedure
Cai, Hongzhu; Čuma, Martin; Zhdanov, Michael
2015-01-01
This paper presents a parallelized version of the edge-based finite element method with a novel post-processing approach for numerical modeling of an electromagnetic field in complex media. The method uses an unstructured tetrahedral mesh which can reduce the number of degrees of freedom signific......This paper presents a parallelized version of the edge-based finite element method with a novel post-processing approach for numerical modeling of an electromagnetic field in complex media. The method uses an unstructured tetrahedral mesh which can reduce the number of degrees of freedom...... significantly. The linear system of finite element equations is solved using parallel direct solvers which are robust for ill-conditioned systems and efficient for multiple source electromagnetic (EM) modeling. We also introduce a novel approach to compute the scalar components of the electric field from...... the tangential components along each edge based on field redatuming. The method can produce a more accurate result as compared to conventional approach. We have applied the developed algorithm to compute the EM response for a typical 3D anisotropic geoelectrical model of the off-shore HC reservoir with complex...
Spiral waves are stable in discrete element models of two-dimensional homogeneous excitable media
Feldman, A. B.; Chernyak, Y. B.; Cohen, R. J.
1998-01-01
The spontaneous breakup of a single spiral wave of excitation into a turbulent wave pattern has been observed in both discrete element models and continuous reaction-diffusion models of spatially homogeneous 2D excitable media. These results have attracted considerable interest, since spiral breakup is thought to be an important mechanism of transition from the heart rhythm disturbance ventricular tachycardia to the fatal arrhythmia ventricular fibrillation. It is not known whether this process can occur in the absence of disease-induced spatial heterogeneity of the electrical properties of the ventricular tissue. Candidate mechanisms for spiral breakup in uniform 2D media have emerged, but the physical validity of the mechanisms and their applicability to myocardium require further scrutiny. In this letter, we examine the computer simulation results obtained in two discrete element models and show that the instability of each spiral is an artifact resulting from an unphysical dependence of wave speed on wave front curvature in the medium. We conclude that spiral breakup does not occur in these two models at the specified parameter values and that great care must be exercised in the representation of a continuous excitable medium via discrete elements.
Kulak, R.F.; Kennedy, J.M.; Belytschko, T.B.; Schoeberle, D.F.
1977-01-01
This paper describes finite-element formulations for the thermal stress analysis of LMFBR structures. The first formulation is applicable to large displacement rotation problems in which the strains are small. For this formulation, a general temperature-dependent constituent relationship is derived from a Gibbs potential function and a temperature dependent yield surface. The temperature dependency of the yield surface is based upon a temperature-dependent, material-hardening model. The model uses a temperature-equivalent stress-plastic strain diagram which is generated from isothermal uniaxial stress-strain data. A second formulation is presented for problems characterized by both large displacement-rotations and large strains. Here a set of large strain hypoelastic-plastic relationships are developed to linearly relate the rate of stress to the rate of deformation. The temperature field is described through time-dependent values at mesh node points; the temperature fields in each element are then obtained by interpolation formulas. Hence, problems with both spatial and temporal dependent temperature fields can easily be treated. The above developments were incorporated into two ANL developed finite-element computer codes: the implicit version of STRAW and the 3D Implicit Structural Analysis Code. STRAW is a two-dimensional code with a plane stress/plane strain beam element. The 3D Implicit code has a triangular flat plate element which is capable of sustaining both membrane and bending loads. To insure numerical stability both codes are based on an iterative-incremental solution procedure with equilibrium checks based on an error in energy
Berezhnoi, D. V.; Balafendieva, I. S.; Sachenkov, A. A.; Sekaeva, L. R.
2017-06-01
In work the technique of calculation of elements of three-dimensional reinforced concrete substructures located in a soil, interacting with each other through rubber linings is realized. To describe the interaction of deformable structures with the ground, special “semi-infinite” finite elements are used. A technique has been implemented that allows one to describe the contact interaction of three-dimensional structures by means of a special contact finite element with specific properties. The obtained numerical results are compared with the experimental data, their good agreement is noted.
Parallelized Three-Dimensional Resistivity Inversion Using Finite Elements And Adjoint State Methods
Schaa, Ralf; Gross, Lutz; Du Plessis, Jaco
2015-04-01
The resistivity method is one of the oldest geophysical exploration methods, which employs one pair of electrodes to inject current into the ground and one or more pairs of electrodes to measure the electrical potential difference. The potential difference is a non-linear function of the subsurface resistivity distribution described by an elliptic partial differential equation (PDE) of the Poisson type. Inversion of measured potentials solves for the subsurface resistivity represented by PDE coefficients. With increasing advances in multichannel resistivity acquisition systems (systems with more than 60 channels and full waveform recording are now emerging), inversion software require efficient storage and solver algorithms. We developed the finite element solver Escript, which provides a user-friendly programming environment in Python to solve large-scale PDE-based problems (see https://launchpad.net/escript-finley). Using finite elements, highly irregular shaped geology and topography can readily be taken into account. For the 3D resistivity problem, we have implemented the secondary potential approach, where the PDE is decomposed into a primary potential caused by the source current and the secondary potential caused by changes in subsurface resistivity. The primary potential is calculated analytically, and the boundary value problem for the secondary potential is solved using nodal finite elements. This approach removes the singularity caused by the source currents and provides more accurate 3D resistivity models. To solve the inversion problem we apply a 'first optimize then discretize' approach using the quasi-Newton scheme in form of the limited-memory Broyden-Fletcher-Goldfarb-Shanno (L-BFGS) method (see Gross & Kemp 2013). The evaluation of the cost function requires the solution of the secondary potential PDE for each source current and the solution of the corresponding adjoint-state PDE for the cost function gradients with respect to the subsurface
Salehipour, Pouya; Nematzadeh, Mahsa; Mobasheri, Maryam Beigom; Afsharpad, Mandana; Mansouri, Kamran; Modarressi, Mohammad Hossein
2017-09-01
Testis specific gene antigen 10 (TSGA10) is a cancer testis antigen involved in the process of spermatogenesis. TSGA10 could also play an important role in the inhibition of angiogenesis by preventing nuclear localization of HIF-1α. Although it has been shown that TSGA10 messenger RNA (mRNA) is mainly expressed in testis and some tumors, the transcription pattern and regulatory mechanisms of this gene remain largely unknown. Here, we report that human TSGA10 comprises at least 22 exons and generates four different transcript variants. It was identified that using two distinct promoters and splicing of exons 4 and 7 produced these transcript variants, which have the same coding sequence, but the sequence of 5'untanslated region (5'UTR) is different between them. This is significant because conserved regulatory RNA elements like upstream open reading frame (uORF) and putative internal ribosome entry site (IRES) were found in this region which have different combinations in each transcript variant and it may influence translational efficiency of them in normal or unusual environmental conditions like hypoxia. To indicate the transcription pattern of TSGA10 in breast cancer, expression of identified transcript variants was analyzed in 62 breast cancer samples. We found that TSGA10 tends to express variants with shorter 5'UTR and fewer uORF elements in breast cancer tissues. Our study demonstrates for the first time the expression of different TSGA10 transcript variants in testis and breast cancer tissues and provides a first clue to a role of TSGA10 5'UTR in regulation of translation in unusual environmental conditions like hypoxia. Copyright © 2017. Published by Elsevier B.V.
Li, Dong Feng; Bai, Fu Qing; Nie, Hui
2018-06-01
In order to analyze the influence of bridge holes widening on hydrodynamic such as water level, a two-dimensional mathematical model was used to calculate the hydrodynamic factors, river network flow velocity vector distribution is given, water level and difference of bridge widening before and after is calculated and charted, water surface gradient in seven different river sections near the upper reaches of bridges is counted and revealed. The results of hydrodynamic calculation indicate that The Maximum and the minimum deducing numerical value of the water level after bridge widening is 0.028m, and 0.018m respective. the seven sections water surface gradient becomes smaller until it becomes negative, the influence of bridge widening on the upstream is basically over, the range of influence is about 450m from the bridge to the upstream. reach
Domanus, J.C.
1981-10-01
In 1979 a working group on neutron radiography was formed at Euratom. The purpose of this group is the standardization of neutron radiographic methods in the field of nuclear fuel. First priority was given to the development of image quality indicators and standard objects for the determination of accuracy of dimensional measurements from neutron radiographs. For that purpose beam purity and sensitivity indicators as well as a calibration fuel pin were designed and fabricated at Risoe. All the Euratom neutron radiography centers have recieved the above items for comparative neutron radiography. The measuring results obtained, using various measuring apparatus, will form the basis to formulate conclusions about the best measuring methods and instruments to be used in that field. (author)
Multi-dimensional Fokker-Planck equation analysis using the modified finite element method
Náprstek, Jiří; Král, Radomil
2016-01-01
Roč. 744, č. 1 (2016), č. článku 012177. ISSN 1742-6588. [International Conference on Motion and Vibration Control (MOVIC 2016) /13./ and International Conference on Recent Advances in Structural Dynamics (RASD 2016) /12./. Southampton, 04.07.2016-06.07.2016] R&D Projects: GA ČR(CZ) GP14-34467P; GA ČR(CZ) GA15-01035S Institutional support: RVO:68378297 Keywords : Fokker-Planck equation * finite element method * single degree of freedom systems (SDOF) Subject RIV: JM - Building Engineering http://iopscience.iop.org/article/10.1088/1742-6596/744/1/012177
Finite elements for the calculation of turbulent flows in three-dimensional complex geometries
Ruprecht, A.
A finite element program for the calculation of incompressible turbulent flows is presented. In order to reduce the required storage an iterative algorithm is used which solves the necessary equations sequentially. The state of turbulence is defined by the k-epsilon model. In addition to the standard k-epsilon model, the modification of Bardina et al., taking into account the rotation of the mean flow, is investigated. With this program, the flow in the draft tube of a Kaplan turbine is examined. Calculations are carried out for swirling and nonswirling entrance flow. The results are compared with measurements.
Smeets, Daniel; Markaki, Yolanda; Schmid, Volker J; Kraus, Felix; Tattermusch, Anna; Cerase, Andrea; Sterr, Michael; Fiedler, Susanne; Demmerle, Justin; Popken, Jens; Leonhardt, Heinrich; Brockdorff, Neil; Cremer, Thomas; Schermelleh, Lothar; Cremer, Marion
2014-01-01
A Xist RNA decorated Barr body is the structural hallmark of the compacted inactive X territory in female mammals. Using super-resolution three-dimensional structured illumination microscopy (3D-SIM) and quantitative image analysis, we compared its ultrastructure with active chromosome territories (CTs) in human and mouse somatic cells, and explored the spatio-temporal process of Barr body formation at onset of inactivation in early differentiating mouse embryonic stem cells (ESCs). We demonstrate that all CTs are composed of structurally linked chromatin domain clusters (CDCs). In active CTs the periphery of CDCs harbors low-density chromatin enriched with transcriptionally competent markers, called the perichromatin region (PR). The PR borders on a contiguous channel system, the interchromatin compartment (IC), which starts at nuclear pores and pervades CTs. We propose that the PR and macromolecular complexes in IC channels together form the transcriptionally permissive active nuclear compartment (ANC). The Barr body differs from active CTs by a partially collapsed ANC with CDCs coming significantly closer together, although a rudimentary IC channel system connected to nuclear pores is maintained. Distinct Xist RNA foci, closely adjacent to the nuclear matrix scaffold attachment factor-A (SAF-A) localize throughout Xi along the rudimentary ANC. In early differentiating ESCs initial Xist RNA spreading precedes Barr body formation, which occurs concurrent with the subsequent exclusion of RNA polymerase II (RNAP II). Induction of a transgenic autosomal Xist RNA in a male ESC triggers the formation of an 'autosomal Barr body' with less compacted chromatin and incomplete RNAP II exclusion. 3D-SIM provides experimental evidence for profound differences between the functional architecture of transcriptionally active CTs and the Barr body. Basic structural features of CT organization such as CDCs and IC channels are however still recognized, arguing against a uniform
ImageParser: a tool for finite element generation from three-dimensional medical images
Yamada T
2004-10-01
Full Text Available Abstract Background The finite element method (FEM is a powerful mathematical tool to simulate and visualize the mechanical deformation of tissues and organs during medical examinations or interventions. It is yet a challenge to build up an FEM mesh directly from a volumetric image partially because the regions (or structures of interest (ROIs may be irregular and fuzzy. Methods A software package, ImageParser, is developed to generate an FEM mesh from 3-D tomographic medical images. This software uses a semi-automatic method to detect ROIs from the context of image including neighboring tissues and organs, completes segmentation of different tissues, and meshes the organ into elements. Results The ImageParser is shown to build up an FEM model for simulating the mechanical responses of the breast based on 3-D CT images. The breast is compressed by two plate paddles under an overall displacement as large as 20% of the initial distance between the paddles. The strain and tangential Young's modulus distributions are specified for the biomechanical analysis of breast tissues. Conclusion The ImageParser can successfully exact the geometry of ROIs from a complex medical image and generate the FEM mesh with customer-defined segmentation information.
Seismic response of three-dimensional topographies using a time-domain boundary element method
Janod, François; Coutant, Olivier
2000-08-01
We present a time-domain implementation for a boundary element method (BEM) to compute the diffraction of seismic waves by 3-D topographies overlying a homogeneous half-space. This implementation is chosen to overcome the memory limitations arising when solving the boundary conditions with a frequency-domain approach. This formulation is flexible because it allows one to make an adaptive use of the Green's function time translation properties: the boundary conditions solving scheme can be chosen as a trade-off between memory and cpu requirements. We explore here an explicit method of solution that requires little memory but a high cpu cost in order to run on a workstation computer. We obtain good results with four points per minimum wavelength discretization for various topographies and plane wave excitations. This implementation can be used for two different aims: the time-domain approach allows an easier implementation of the BEM in hybrid methods (e.g. coupling with finite differences), and it also allows one to run simple BEM models with reasonable computer requirements. In order to keep reasonable computation times, we do not introduce any interface and we only consider homogeneous models. Results are shown for different configurations: an explosion near a flat free surface, a plane wave vertically incident on a Gaussian hill and on a hemispherical cavity, and an explosion point below the surface of a Gaussian hill. Comparison is made with other numerical methods, such as finite difference methods (FDMs) and spectral elements.
Czarnecki, J.B.; Faunt, C.C.; Gable, C.W.; Zyvoloski, G.A.
1996-01-01
Development of a preliminary three-dimensional model of the saturated zone at Yucca Mountain, the potential location for a high-level nuclear waste repository, is presented. The development of the model advances the technology of interfacing: (1)complex three-dimensional hydrogeologic framework modeling; (2) fully three-dimensional, unstructured, finite-element mesh generation; and (3) groundwater flow, heat, and transport simulation. The three-dimensional hydrogeologic framework model is developed using maps, cross sections, and well data. The framework model data are used to feed an automated mesh generator, designed to discretize irregular three-dimensional solids,a nd to assign materials properties from the hydrogeologic framework model to the tetrahedral elements. The mesh generator facilitated the addition of nodes to the finite-element mesh which correspond to the exact three-dimensional position of the potentiometric surface based on water-levels from wells. A ground water flow and heat simulator is run with the resulting finite- element mesh, within a parameter-estimation program. The application of the parameter-estimation program is designed to provide optimal values of permeability and specified fluxes over the model domain to minimize the residual between observed and simulated water levels
Vishal Shrishail Kudagi
2017-01-01
Full Text Available Background and Objectives: Connecting the contralateral upper molars by means of a transpalatal arch (TPA is thought to decrease the tendency of the molars to move mesially in response to orthodontic force (i.e., provide orthodontic anchorage. This study was hence conducted to investigate the effects of the TPA on the displacement of the molars and stresses generated in the periodontium during orthodontic tooth movement using the finite element method (FEM. Materials and Methods: A three-dimensional (3D model was generated using medical modeling software (Mimics using the computed tomography slice images of the skull which were obtained at a slice thickness of 1 mm. From this, the finite element model was built using HyperMesh and analysis was performed using PATRAN software (MSC Software Corporation, 4675 MacArthur Court, Newport Beach, California 92660. The 3D finite element models were fabricated in two versions such as maxillary first molars including their associated periodontal ligament and alveolar bone one with TPA and another without TPA. Both were subjected to orthodontic forces, and the resultant stress patterns and displacements between the models with and without TPA were determined. Results: The stress and displacement plots in this study failed to show any significant differences in stress and displacement within the periodontium of molars, between the two models – one with TPA and the other without, in response to the orthodontic force. Interpretation and Conclusion: The results of the current finite element analysis, therefore, suggest that the presence of a TPA brings about no change in the initial dental and periodontal stress distribution and displacement.
B-spline based finite element method in one-dimensional discontinuous elastic wave propagation
Kolman, Radek; Okrouhlík, Miloslav; Berezovski, A.; Gabriel, Dušan; Kopačka, Ján; Plešek, Jiří
2017-01-01
Roč. 46, June (2017), s. 382-395 ISSN 0307-904X R&D Projects: GA ČR(CZ) GAP101/12/2315; GA MŠk(CZ) EF15_003/0000493 Grant - others:AV ČR(CZ) DAAD-16-12; AV ČR(CZ) ETA-15-03 Program:Bilaterální spolupráce; Bilaterální spolupráce Institutional support: RVO:61388998 Keywords : discontinuous elastic wave propagation * B-spline finite element method * isogeometric analysis * implicit and explicit time integration * dispersion * spurious oscillations Subject RIV: BI - Acoustics OBOR OECD: Acoustics Impact factor: 2.350, year: 2016 http://www.sciencedirect.com/science/article/pii/S0307904X17300835
Solution of three-dimensional energy equation using finite element method
Bhasin, V.; Singh, R.K.; Dutta, B.K.; Kushwaha, H.S.
1993-01-01
In the present work an attempt has been made to formulate an efficient 3-D finite element program for solving coupled momentum-energy equation with unsymmetric frontal solver and a suitable upwinding scheme. Based on the above solution technique of energy equation it can be concluded that upwinding scheme can lead to fairly accurate and smooth results even with coarse mesh. Otherwise the mesh size requirement will be extremely stringent for most of the practical problems. With upwinding the additional computer time required is marginally more. This effort has resulted in getting practical solution for large size real life problems in nuclear industry. The program was used for computation of temperature field in heavy water moderator of Madras Atomic Power Station (MAPS) reactor, in new mode of operation. (author). 9 refs., 7 figs
Masiello, E.; Sanchez, R.
2007-01-01
A discontinuous heterogeneous finite element method is presented and discussed. The method is intended for realistic numerical pin-by-pin lattice calculations when an exact representation of the geometric shape of the pins is made without need for homogenization. The method keeps the advantages of conventional discrete ordinate methods, such as fast execution together with the possibility to deal with a large number of spatial meshes, while minimizing the need for geometric modeling. It also provides a complete factorization in space, angle, and energy for the discretized matrices and minimizes, thus, storage requirements. An angular multigrid acceleration technique has also been developed to speed up the rate of convergence of the inner iterations. A particular aspect of this acceleration is the introduction of boundary restriction and prolongation operators that minimize oscillatory behavior and enhance positivity. Numerical tests are presented that show the high precision of the method and the efficiency of the angular multigrid acceleration. (authors)
Two Dimensional Finite Element Analysis for the Effect of a Pressure Wave in the Human Brain
Ponce L., Ernesto; Ponce S., Daniel
2008-11-01
Brain injuries in people of all ages is a serious, world-wide health problem, with consequences as varied as attention or memory deficits, difficulties in problem-solving, aggressive social behavior, and neuro degenerative diseases such as Alzheimer's and Parkinson's. Brain injuries can be the result of a direct impact, but also pressure waves and direct impulses. The aim of this work is to develop a predictive method to calculate the stress generated in the human brain by pressure waves such as high power sounds. The finite element method is used, combined with elastic wave theory. The predictions of the generated stress levels are compared with the resistance of the arterioles that pervade the brain. The problem was focused to the Chilean mining where there are some accidents happen by detonations and high sound level. There are not formal medical investigation, however these pressure waves could produce human brain damage.
Numerical stress analysis of toroidal coil by three-dimensional finite element method
Nishimura, Hidetomo; Shimamoto, Susumu
1977-10-01
A structure analysis program based on finite element method for toroidal coils, developed in JAERI, and its example application to a medium-size tokamak are described. In this application, the effects of material anisotropy, poloidal field and spring constant value were studied, and also the influence of toroidal coil failure on the peak stress. The following were revealed. The effect of anisotropy on the peak stress in reinforcement must be considered. The effect of poloidal field on the peak stress is small compared with that of toroidal field. The spring constant value between coil and support does not much influence the peak stress value, The peak stress in reinforcement rises with increasing number of failed coils. In the case of 2000 nodes on the structure, CPU time with the program is about 40 min. (auth.)
Viner, K.; Reinecke, P. A.; Gabersek, S.; Flagg, D. D.; Doyle, J. D.; Martini, M.; Ryglicki, D.; Michalakes, J.; Giraldo, F.
2016-12-01
NEPTUNE: the Navy Environmental Prediction sysTem Using the NUMA*corE, is a 3D spectral element atmospheric model composed of a full suite of physics parameterizations and pre- and post-processing infrastructure with plans for data assimilation and coupling components to a variety of Earth-system models. This talk will focus on the initial struggles and solutions in adapting NUMA for stable and accurate integration on the sphere using both the deep atmosphere equations and a newly developed shallow-atmosphere approximation, as demonstrated through idealized test cases. In addition, details of the physics-dynamics coupling methodology will be discussed. NEPTUNE results for test cases from the 2016 Dynamical Core Model Intercomparison Project (DCMIP-2016) will be shown and discussed. *NUMA: Nonhydrostatic Unified Model of the Atmosphere; Kelly and Giraldo 2012, JCP
Xiong Yuhong; Hofmeister, William H.; Cheng Zhao; Smugeresky, John E.; Lavernia, Enrique J.; Schoenung, Julie M.
2009-01-01
Laser deposition is being used for the fabrication of net shapes from a broad range of materials, including tungsten carbide-cobalt (WC-Co) cermets (composites composed of a metallic phase and a hard refractory phase). During deposition, an unusual thermal condition is created for cermets, resulting in rather complex microstructures. To provide a fundamental insight into the evolution of such microstructures, we studied the thermal behavior of WC-Co cermets during laser deposition involving complementary results from in situ high-speed thermal imaging and three-dimensional finite element modeling. The former allowed for the characterization of temperature gradients and cooling rates in the vicinity of the molten pool, whereas the latter allowed for simulation of the entire sample. By combining the two methods, a more robust analysis of the thermal behavior was achieved. The model and the imaging results correlate well with each other and with the alternating sublayers observed in the microstructure.
Liu Bing
2014-10-01
Full Text Available Earthquake action is the main external factor which influences long-term safe operation of civil construction, especially of the high-rise building. Applying time-history method to simulate earthquake response process of civil construction foundation surrounding rock is an effective method for the anti-knock study of civil buildings. Therefore, this paper develops a civil building earthquake disaster three-dimensional dynamic finite element numerical simulation system. The system adopts the explicit central difference method. Strengthening characteristics of materials under high strain rate and damage characteristics of surrounding rock under the action of cyclic loading are considered. Then, dynamic constitutive model of rock mass suitable for civil building aseismic analysis is put forward. At the same time, through the earthquake disaster of time-history simulation of Shenzhen Children’s Palace, reliability and practicability of system program is verified in the analysis of practical engineering problems.
Mellor, A.; Domenech-Garret, J.L.; Chemisana, D.; Rosell, J.I. [Departament de Medi Ambient i C.S., University of Lleida, Av. Alcalde Rovira Roure 191, E25198 (Spain)
2009-09-15
A two-dimensional finite element model of current flow in the front surface of a PV cell is presented. In order to validate this model we perform an experimental test. Later, particular attention is paid to the effects of non-uniform illumination in the finger direction which is typical in a linear concentrator system. Fill factor, open circuit voltage and efficiency are shown to decrease with increasing degree of non-uniform illumination. It is shown that these detrimental effects can be mitigated significantly by reoptimization of the number of front surface metallization fingers to suit the degree of non-uniformity. The behavior of current flow in the front surface of a cell operating at open circuit voltage under non-uniform illumination is discussed in detail. (author)
Zhang, Yi; Zhang, Lei; Fan, Yu-bo; Song, Jin-lin; Deng, Feng
2009-10-01
To investigate the biomechanical effects of micro-implant anchorage technique with sliding mechanics on maxillary anterior teeth retraction under different implant insertion heights and different retraction hook heights. The three dimensional finite element model of maxillary anterior teeth retraction force system was constructed with CT scanning and MIMICS software and the relationships between brackets, teeth, wire and micro-implant were simulating the clinical factions. Then the initial tooth displacement was calculated when the insertion heights were 4 mm and 8 mm and the retraction hook heights were 1, 4, 7, 10 mm respectively. With retraction hook height added, the anterior teeth movement changed from lingual crown tipping to labial crown tipping and the intrusion movement was more apparent when the micro-implant was inserted in a higher location. The ideal teeth movement control could be achieved by different insertion heights of micro-implant and different retraction hook heights in straight wire retraction force system.
Leapman, R.D.; Kocsis, E.; Zhang, G.; Talbot, T.L.; Laquerriere, P
2004-07-15
By combining electron tomography with energy-filtered electron microscopy, we have shown the feasibility of determining the three-dimensional distributions of phosphorus in biological specimens. Thin sections of the nematode, Caenorhabditis elegans were prepared by high-pressure freezing, freeze-substitution and plastic embedding. Images were recorded at energy losses above and below the phosphorus L{sub 2,3} edge using a post-column imaging filter operating at a beam energy of 120 keV. The unstained specimens exhibited minimal contrast in bright-field images. After it was determined that the specimen was sufficiently thin to allow two-window ratio imaging of phosphorus, pairs of pre-edge and post-edge images were acquired in series over a tilt range of {+-}55 deg. at 5 deg. increments for two orthogonal tilt axes. The projected phosphorus distributions were aligned using the pre-edge images that contained inelastic contrast from colloidal gold particles deposited on the specimen surface. A reconstruction and surface rendering of the phosphorus distribution clearly revealed features 15-20 nm in diameter, which were identified as ribosomes distributed along the stacked membranes of endoplasmic reticulum and in the cytoplasm. The sensitivity of the technique was estimated at <35 phosphorus atoms per voxel based on the known total ribosomal phosphorus content of approximately 7000 atoms. Although a high electron dose of approximately 10{sup 7} e/nm{sup 2} was required to record two-axis tilt series, specimens were sufficiently stable to allow image alignment and tomographic reconstruction.
Chunjiang Zhao
2016-10-01
Full Text Available Sensing and mapping element distributions in plant tissues and its growth environment has great significance for understanding the uptake, transport, and accumulation of nutrients and harmful elements in plants, as well as for understanding interactions between plants and the environment. In this study, we developed a 3-dimensional elemental mapping system based on laser-induced breakdown spectroscopy that can be deployed in- field to directly measure the distribution of multiple elements in living plants as well as in the soil. Mapping is performed by a fast scanning laser, which ablates a micro volume of a sample to form a plasma. The presence and concentration of specific elements are calculated using the atomic, ionic, and molecular spectral characteristics of the plasma emission spectra. Furthermore, we mapped the pesticide residues in maize leaves after spraying to demonstrate the capacity of this method for trace elemental mapping. We also used the system to quantitatively detect the element concentrations in soil, which can be used to further understand the element transport between plants and soil. We demonstrate that this method has great potential for elemental mapping in plant tissues and soil with the advantages of 3-dimensional and multi-elemental mapping, in situ and in vivo measurement, flexible use, and low cost.
Ubaidillah; Permata, A. N. S.; Mazlan, S. A.; Tjahjana, D. D. D. P.; Widodo, P. J.
2017-10-01
This research delivers a finite element magnetic simulation of a novel disk type multi-coil magnetorheological brake (MR brake). The MR brake axial design had more than one coil located outside of the casing. This design could simplify the maintenance process of brakes. One pair of coils was used as the representative of the entire coil in the simulation process, and it could distribute magnetic flux in all parts of the electromagnetic. The objective of this simulation was to produce magnetic flux on the surface of the disc brake rotor. The value of the MR brake magnetic flux was higher than that of the current MR brake having one coil with a larger size. The result of the simulation would be used to identify the effect of different fluids on each variation. The Magneto-rheological fluid MRF-132DG and MRF-140CG were injected in each gap as much as 0.50, 1.00, and 1.50 mm, respectively. On the simulation process, the coils were energized at 0.25, 0.50, 0.75, 1.00, 1.50, and 2.00 A, respectively. The magnetic flux produced by MRF-140CG was 336 m Tesla on the gap of 0.5 mm. The result of the simulation shows that the smaller the gap variation was, the higher the magnetic value was.
A comparison of two three-dimensional shell-element transient electromagnetics codes
Yugo, J.J.; Williamson, D.E.
1992-01-01
Electromagnetic forces due to eddy currents strongly influence the design of components for the next generation of fusion devices. An effort has been made to benchmark two computer programs used to generate transient electromagnetic loads: SPARK and EddyCuFF. Two simple transient field problems were analyzed, both of which had been previously analyzed by the SPARK code with results recorded in the literature. A third problem that uses an ITER inboard blanket benchmark model was analyzed as well. This problem was driven with a self-consistent, distributed multifilament plasma model generated by an axisymmetric physics code. The benchmark problems showed good agreement between the two shell-element codes. Variations in calculated eddy currents of 1--3% have been found for similar, finely meshed models. A difference of 8% was found in induced current and 20% in force for a coarse mesh and complex, multifilament field driver. Because comparisons were made to results obtained from literature, model preparation and code execution times were not evaluated
Wang, Feiyan; Morten, Jan Petter; Spitzer, Klaus
2018-05-01
In this paper, we present a recently developed anisotropic 3-D inversion framework for interpreting controlled-source electromagnetic (CSEM) data in the frequency domain. The framework integrates a high-order finite-element forward operator and a Gauss-Newton inversion algorithm. Conductivity constraints are applied using a parameter transformation. We discretize the continuous forward and inverse problems on unstructured grids for a flexible treatment of arbitrarily complex geometries. Moreover, an unstructured mesh is more desirable in comparison to a single rectilinear mesh for multisource problems because local grid refinement will not significantly influence the mesh density outside the region of interest. The non-uniform spatial discretization facilitates parametrization of the inversion domain at a suitable scale. For a rapid simulation of multisource EM data, we opt to use a parallel direct solver. We further accelerate the inversion process by decomposing the entire data set into subsets with respect to frequencies (and transmitters if memory requirement is affordable). The computational tasks associated with each data subset are distributed to different processes and run in parallel. We validate the scheme using a synthetic marine CSEM model with rough bathymetry, and finally, apply it to an industrial-size 3-D data set from the Troll field oil province in the North Sea acquired in 2008 to examine its robustness and practical applicability.
Castejón, L.
1997-12-01
Full Text Available Sandwich-type structures have proved to be alternatives of great success for several fields of application, and specially in the building sector. This is due to their outstanding properties of .specific rigidity and strength against bending loads and other range of advantages like fatigue and impact resistance, attainment of flat and smooth surfaces, high electric and thermal insulation, design versatility and some others. However, traditional sandwich structures present problems like their tendency towards delamination, stress concentrations in bores or screwed Joints, and pre resistance. These problems are alleviated thanks to the use of new sandwich structures built using three dimensional structures of advanced composite materials, maintaining the present advantages for more traditional sandwich structures. At this rate, these new structures can be applied in several areas where conventional sandwich structures used to be like walls, partitions, floor and ceiling structures, domes, vaults and dwellings, but with greater success.
Las estructuras tipo sándwich han demostrado ser alternativas de gran éxito para diversos campos de aplicación y, en concreto, en el sector de la construcción, listo es gracias a sus excelentes propiedades de rigidez y resistencia específica frente a cargas de flexión y otra larga lista de ventajas, a la que pertenecen, por ejemplo, su buena resistencia a fatiga, resistencia al impacto, obtención de superficies lisas y suaves, elevado aislamiento térmico y eléctrico, versatilidad de diseño y otras. Sin embargo, las estructuras sándwich, tradicionales presentan una problemática consistente en su tendencia a la delaminación, concentraciones de tensiones ¿aparecidas ante la existencia de agujeros o uniones atornilladas y resistencia al fuego. Estos problemas son pifiados gracias a la aplicación de estructuras novedosas tipo sándwich, construidas a partir de tejidos tridimensionales de materiales
Cheng-dong Piao; Kun Yang; Peng Li; Min Luo
2015-01-01
In the repair of peripheral nerve injury using autologous or synthetic nerve grafting, the mag-nitude of tensile forces at the anastomosis affects its response to physiological stress and the ultimate success of the treatment. One-dimensional stretching is commonly used to measure changes in tensile stress and strain; however, the accuracy of this simple method is limited. There-fore, in the present study, we established three-dimensional ifnite element models of sciatic nerve defects repaired by autologous nerve grafts. Using PRO E 5.0 ifnite element simulation software, we calculated the maximum stress and displacement of an anastomosis under a 5 N load in 10-, 20-, 30-, 40-mm long autologous nerve grafts. We found that maximum displacement increased with graft length, consistent with specimen force. These ifndings indicate that three-dimensional ifnite element simulation is a feasible method for analyzing stress and displacement at the anas-tomosis after autologous nerve grafting.
Cheng-dong Piao
2015-01-01
Full Text Available In the repair of peripheral nerve injury using autologous or synthetic nerve grafting, the magnitude of tensile forces at the anastomosis affects its response to physiological stress and the ultimate success of the treatment. One-dimensional stretching is commonly used to measure changes in tensile stress and strain however, the accuracy of this simple method is limited. Therefore, in the present study, we established three-dimensional finite element models of sciatic nerve defects repaired by autologous nerve grafts. Using PRO E 5.0 finite element simulation software, we calculated the maximum stress and displacement of an anastomosis under a 5 N load in 10-, 20-, 30-, 40-mm long autologous nerve grafts. We found that maximum displacement increased with graft length, consistent with specimen force. These findings indicate that three-dimensional finite element simulation is a feasible method for analyzing stress and displacement at the anastomosis after autologous nerve grafting.
Yang, Wenting; Wang, Dongmei; Lei, Zhoujixin; Wang, Chunhui; Chen, Shanguang
2017-12-01
Astronauts who are exposed to weightless environment in long-term spaceflight might encounter bone density and mass loss for the mechanical stimulus is smaller than normal value. This study built a three dimensional model of human femur to simulate the remodeling process of human femur during bed rest experiment based on finite element analysis (FEA). The remodeling parameters of this finite element model was validated after comparing experimental and numerical results. Then, the remodeling process of human femur in weightless environment was simulated, and the remodeling function of time was derived. The loading magnitude and loading cycle on human femur during weightless environment were increased to simulate the exercise against bone loss. Simulation results showed that increasing loading magnitude is more effective in diminishing bone loss than increasing loading cycles, which demonstrated that exercise of certain intensity could help resist bone loss during long-term spaceflight. At the end, this study simulated the bone recovery process after spaceflight. It was found that the bone absorption rate is larger than bone formation rate. We advise that astronauts should take exercise during spaceflight to resist bone loss.
Fujimura, T.; Nakahara, Y.; Matsumura, M.
1983-01-01
A double finite element method (DFEM), in which both the space-and-angle finite elements are employed, has been formulated and computer codes have been developed to solve the static multigroup neutron transport problems in the three-dimensional geometry. Two methods, Galerkin's weighted residual and variational are used to apply the DFEM to the transport equation. The variational principle requires complicated formulation than the Galerkin method, but the boundary conditions can be automatically incorporated and each plane equation becomes symmetric. The system equations are solved over the planar layers which we call plane iteration. The coarse mesh rebalancing technique is used for the inner iteration and the outer iteration is accelerated by extra-polation. Numerical studies of these two DFEM algorithms have been done in comparison between them and also with THe CITATION and TWOTRAN-II results. It has been confirmed that in the case of variational formulation an adaptive acceleration method of the SSOR iteration works effectively and the ray effects are mitigated in both DFEM algorithms. (author)
Rezende, Carlos Eduardo Edwards; Chase-Diaz, Melody; Costa, Max Doria; Albarracin, Max Laurent; Paschoeto, Gabriela; Sousa, Edson Antonio Capello; Rubo, José Henrique; Borges, Ana Flávia Sanches
2015-10-01
This study aimed to analyze the stress distribution in single implant system and to evaluate the compatibility of an in vitro model with finite element (FE) model. The in vitro model consisted of Brånemark implant; multiunit set abutment of 5 mm height; metal-ceramic screw-retained crown, and polyurethane simulating the bone. Deformations were recorded in the peri-implant region in the mesial and distal aspects, after an axial 300 N load application at the center of the occlusal aspect of the crown, using strain gauges. This in vitro model was scanned with micro CT to design a three-dimensional FE model and the strains in the peri-implant bone region were registered to check the compatibility between both models. The FE model was used to evaluate stress distribution in different parts of the system. The values obtained from the in vitro model (20-587 με) and the finite element analysis (81-588 με) showed agreement among them. The highest stresses because of axial and oblique load, respectively were 5.83 and 40 MPa for the cortical bone, 55 and 1200 MPa for the implant, and 80 and 470 MPa for the abutment screw. The FE method proved to be effective for evaluating the deformation around single implant. Oblique loads lead to higher stress concentrations.
Yamaguchi, Satoshi; Tsutsui, Kihei; Satake, Koji; Morikawa, Shigehiro; Shirai, Yoshiaki; Tanaka, Hiromi T
2014-10-01
Our goal was to develop a three-dimensional finite element model that enables dynamic analysis of needle insertion for soft materials. To demonstrate large deformation and fracture, we used the arbitrary Lagrangian-Eulerian (ALE) method for fluid analysis. We performed ALE-based finite element analysis for 3% agar gel and three types of copper needle with bevel tips. To evaluate simulation results, we compared the needle deflection and insertion force with corresponding experimental results acquired with a uniaxial manipulator. We studied the shear stress distribution of agar gel on various time scales. For 30°, 45°, and 60°, differences in deflections of each needle between both sets of results were 2.424, 2.981, and 3.737mm, respectively. For the insertion force, there was no significant difference for mismatching area error (p<0.05) between simulation and experimental results. Our results have the potential to be a stepping stone to develop pre-operative surgical planning to estimate an optimal needle insertion path for MR image-guided microwave coagulation therapy and for analyzing large deformation and fracture in biological tissues. Copyright © 2014 Elsevier Ltd. All rights reserved.
Shimizu, Hiroyuki; Kikuchi, Hirohito; Fujita, Tomoo; Tanai, Kenji
2011-10-01
For geological isolation systems for radioactive waste, bentonite based material is assumed to be used as a buffer material. The swelling characteristics of the bentonite based material are expected to fill up the void space around the radioactive wastes by swelling. In general, swelling characteristics and properties of bentonite are evaluated by the laboratory tests. However, due to the lack of standardization of testing method for bentonite, the accuracy and reproducibility of the testing results are not sufficiently proved. In this study, bentonite swelling pressure test were simulated by newly developed Distinct Element Method (DEM) code, and the effects of wall friction force and aspect ratio of bentonite specimen were discussed. As a result, the followings were found. In the beginning of the swelling pressure test, since swelling occurs only around the fluid injection side of the specimen, wall friction force acts only in the swelling area and the specimen moves to opposite side from fluid injection side. However, when the entire specimen started swelling, displacement of the specimen prevented by the wall friction force, and the specimen is pressed against the pressure measurement side. Then, the swelling pressure measured on the pressure measurement side increases. Such displacement in the specimen is significantly affected by the decreasing of mechanical properties and the difference of saturation in the bentonite specimen during the fluid infiltration. Moreover, when the aspect ratio of the specimen is large, the displacement of the particle in the specimen becomes large and the area on which the wall frictional force acts is also large. Therefore, measured swelling pressure increases more greatly as the aspect ratio of the specimen increases. To contributes to the standardization of laboratory test methods for bentonite, these effects of wall friction force revealed by the DEM simulation should be verified through laboratory experiments. (author)
NONE
1982-03-01
For the purpose of contributing to the efficient R and D of three-dimensional circuit element technologies (laminated high density integrated element technology, laminated high-speed multi-functional integrated element technology, and laminated large capacity multi-functional integrated element technology), conducted were the survey of domestic and overseas technological trend, investigation of progress status of R and D, and extraction and analysis of problems concerning R and D. In the technological trend survey, the technologies that could sprout in the future were investigated and examined. In addition, examined as much as possible at the present time were the appearance as a device imaginable at the time of the development of the three-dimensional circuit element technology, the point at issue, essential technologies for the development of the element, etc., with the results reported. A report was made on the technology of obtaining a silicon crystal layer on an insulating object. The status quo of a technology for forming an insulated film suitable for a silicon multi-layer structure and of a technology for forming an electrode material was explained, as was a layer forming technology for an insulating object and a metallic material concerning a compound semiconductor layer technology. With the present status summarized on an image sensor in two dimensions, the transmission electron microscope method was introduced. Last of all, investigation results were compiled on the state of progress of each research for the three-dimensional circuit element technology. (NEDO)
Mojtaba Mahmoodi
2017-09-01
Full Text Available Introduction: In post-core crown restorations, the use of prefabricated composite posts concentrate stress at the cervical region and the use of metal posts (prefabricated and customized posts concentrates stress at the interfaces. Fiber reinforced composite posts (FRCs with oval cross-section (oval posts were proposed for post-core crown restorations to reduce the stress levels at the cervical region. The aim of the present study was to investigate the impact of oval cross-section composite posts on stress distribution of premolar with oval-shaped canal by using three-dimensional (3D finite element analysis. Materials and Methods: An extracted premolar tooth was mounted, sectioned, and photographed to create a 3D model. The surrounding tissues of the tooth, periodontal ligament, as well as cortical and trabecular bones were modeled. Seven taper posts with two different cross-section geometries (circular and oval shapes were modeled, as well. Then, the effect of post geometry, post material (carbon fiber and fiberglass, and cement material were investigated by 3D finite element analysis and the stress distribution results were compared. Results: In all the models, the highest stress levels of the dentin were accumulated at the coronal third of the root, and the highest stress levels at the bonding layers were accumulated at the cervical margin. Narrow circular posts induced the highest stress levels, whereas the stress levels were reduced by using thick oval posts. Application of elastic cement reduces the stress at the bonding layers but increases stress at the dentin. Conclusion: Finite element analysis showed that prefabricated oval posts are superior to traditional circular ones. The use of cement with low elastic modulus reduces the risk of debonding but raises the risk of root fracture.
Ahmed, H.; Ma, D.
1979-01-01
A simplified three dimensional finite element model of a pool type LMFBR in conjunction with the computer program ANSYS is developed and scoping results of seismic analysis are produced. Through this study various structural attachments of a pool type LMFBR like the reactor vessel skirt support, the pump support and reactor shell-support structure interfaces are studied. This study also provides some useful results on equivalent viscous damping approach and some improvements to the treatment of equivalent viscous damping are recommended. This study also sets forth pertinent guidelines for detailed three dimensional finite element seismic analysis of pool type LMFBR
Pascal Candas, C.
2002-01-01
Two decades after their birth, the validity of fault slip inversion methods is still strongly debated. These methods are based upon a very simplified mechanical background, the Wallace-Bott hypothesis. Following previous studies, the 3D Distinct Element Method (3DEC software) is used to explore the
de Souza, Fernando Isquierdo; Poi, Wilson Roberto; da Silva, Vanessa Ferreira; Martini, Ana Paula; Melo, Regis Alexandre da Cunha; Panzarini, Sonia Regina; Rocha, Eduardo Passos
2015-06-01
The aim was to evaluate the biomechanical behavior of the supporting bony structures of replanted teeth and the periodontal ligament (PDL) of adjacent teeth when orthodontic wires with different mechanical properties are applied, with three-dimensional finite element analysis. Based on tomographic and microtomographic data, a three-dimensional model of the anterior maxilla with the corresponding teeth (tooth 13-tooth 23) was generated to simulate avulsion and replantation of the tooth 21. The teeth were splinted with orthodontic wire (Ø 0.8 mm) and composite resin. The elastic modulus of the three orthodontic wires used, that is, steel wire (FA), titanium-molybdenum wire (FTM), and nitinol wire (FN) were 200 GPa, 84 GPa, and 52 GPa, respectively. An oblique load (100 N) was applied at an angle of 45° on the incisal edge of the replanted tooth and was analyzed using Ansys Workbench software. The maximum (σmax) and minimum (σmin) principal stresses generated in the PDL, cortical and alveolar bones, and the modified von Mises (σvM) values for the orthodontic wires were obtained. With regard to the cortical bone and PDL, the highest σmin and σmax values for FTM, FN, and FA were checked. With regard to the alveolar bone, σmax and σmin values were highest for FA, followed by FTM and FN. The σvM values of the orthodontic wires followed the order of rigidity of the alloys, that is, FA > FTM > FN. The biomechanical behavior of the analyzed structures with regard to all the three patterns of flexibility was similar. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Chen, Wen-Ming; Lee, Sung-Jae; Lee, Peter Vee Sin
2015-02-26
Therapeutic footwear with specially-made insoles is often used in people with diabetes and rheumatoid arthritis to relieve ulcer risks and pain due to high pressures from areas beneath bony prominences of the foot, in particular to the metatarsal heads (MTHs). In a three-dimensional finite element study of the foot and footwear with sensitivity analysis, effects of geometrical variations of a therapeutic insole, in terms of insole thicknesses and metatarsal pad (MP) placements, on local peak plantar pressure under MTHs and stress/strain states within various forefoot tissues, were determined. A validated musculoskeletal finite element model of the human foot was employed. Analyses were performed in a simulated muscle-demanding instant in gait. For many design combinations, increasing insole thicknesses consistently reduce peak pressures and internal tissue strain under MTHs, but the effects reach a plateau when insole becomes very thick (e.g., a value of 12.7mm or greater). Altering MP placements, however, showed a proximally- and a distally-placed MP could result in reverse effects on MTH pressure-relief. The unsuccessful outcome due to a distally-placed MP may attribute to the way it interacts with plantar tissue (e.g., plantar fascia) adjacent to the MTH. A uniform pattern of tissue compression under metatarsal shaft is necessary for a most favorable pressure-relief under MTHs. The designated functions of an insole design can best be achieved when the insole is very thick, and when the MP can achieve a uniform tissue compression pattern adjacent to the MTH. Copyright © 2015 Elsevier Ltd. All rights reserved.
Yan, Yongli; Zhang, Chuang; Yao, Jiannian; Zhao, Yong Sheng
2013-07-19
Many recent activities in the use of one-dimensional nanostructures as photonic elements for optical information processing are explained by huge advantages that photonic circuits possess over traditional silicon-based electronic ones in bandwidth, heat dissipation, and resistance to electromagnetic wave interference. Organic materials are a promising candidate to support these optical-related applications, as they combine the properties of plastics with broad spectral tunability, high optical cross-section, easy fabrication, as well as low cost. Their outstanding compatibility allows organic composite structures which are made of two or more kinds of materials combined together, showing great superiority to single-component materials due to the introduced interactions among multiple constituents, such as energy transfer, electron transfer, exciton coupling, etc. The easy processability of organic 1D crystalline heterostructures enables a fine topological control of both composition and geometry, which offsets the intrinsic deficiencies of individual material. At the same time, the strong exciton-photon coupling and exciton-exciton interaction impart the excellent confinement of photons in organic microstructures, thus light can be manipulated according to our intention to realize specific functions. These collective properties indicate a potential utility of organic heterogeneous material for miniaturized photonic circuitry. Herein, focus is given on recent advances of 1D organic crystalline heterostructures, with special emphasis on the novel design, controllable construction, diverse performance, as well as wide applications in isolated photonic elements for integration. It is proposed that the highly coupled, hybrid optical networks would be an important material basis towards the creation of on-chip optical information processing. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Zhao, Y.; Qin, R. S.; Chen, D. F.
2013-08-01
A three-dimensional (3D) cellular automata (CA) model has been developed for the simulation of microstructure evolution in alloy solidification. The governing rule for the CA model is associated with the phase transition driving force which is obtained via a thermodynamic database. This determines the migration rate of the non-equilibrium solid-liquid (SL) interface and is calculated according to the local temperature and chemical composition. The curvature of the interface and the anisotropic property of the surface energy are taken into consideration. A 3D finite element (FE) method is applied for the calculation of transient heat and mass transfer. Numerical calculations for the solidification of Fe-1.5 wt% C alloy have been performed. The morphological evolution of dendrites, carbon segregation and temperature distribution in both isothermal and non-isothermal conditions are studied. The parameters affecting the growth of equiaxed and columnar dendrites are discussed. The calculated results are verified using the analytical model and previous experiments. The method provides a sophisticated approach to the solidification of multi-phase and multi-component systems.
1DFEMWATER: A one-dimensional finite element model of WATER flow through saturated-unsaturated media
Yeh, G.T.
1988-08-01
This report presents the development and verification of a one- dimensional finite element model of water flow through saturated- unsaturated media. 1DFEMWATER is very flexible and capable of modeling a wide range of real-world problems. The model is designed to (1) treat heterogeneous media consisting of many geologic formations; (2) consider distributed and point sources/sinks that are spatially and temporally variable; (3) accept prescribed initial conditions or obtain them from steady state simulations; (4) deal with transient heads distributed over the Dirichlet boundary; (5) handle time-dependent fluxes caused by pressure gradient on the Neumann boundary; (6) treat time-dependent total fluxes (i.e., the sum of gravitational fluxes and pressure-gradient fluxes) on the Cauchy boundary; (7) automatically determine variable boundary conditions of evaporation, infiltration, or seepage on the soil-air interface; (8) provide two options for treating the mass matrix (consistent and lumping); (9) provide three alternatives for approximating the time derivative term (Crank-Nicolson central difference, backward difference, and mid-difference); (10) give three options (exact relaxation, underrelaxation, and overrelaxation) for estimating the nonlinear matrix; (11) automatically reset the time step size when boundary conditions or source/sinks change abruptly; and (12) check mass balance over the entire region for every time step. The model is verified with analytical solutions and other numerical models for three examples
Robbins, Joshua; Voth, Thomas
2011-06-01
Material response to dynamic loading is often dominated by microstructure such as grain topology, porosity, inclusions, and defects; however, many models rely on assumptions of homogeneity. We use the probabilistic finite element method (WK Liu, IJNME, 1986) to introduce local uncertainty to account for material heterogeneity. The PFEM uses statistical information about the local material response (i.e., its expectation, coefficient of variation, and autocorrelation) drawn from knowledge of the microstructure, single crystal behavior, and direct numerical simulation (DNS) to determine the expectation and covariance of the system response (velocity, strain, stress, etc). This approach is compared to resolved grain-scale simulations of the equivalent system. The microstructures used for the DNS are produced using Monte Carlo simulations of grain growth, and a sufficient number of realizations are computed to ensure a meaningful comparison. Finally, comments are made regarding the suitability of one-dimensional PFEM for modeling material heterogeneity. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.
La Marra, D.; Battaglia, M.
2013-12-01
Mono Basin is a north-trending graben that extends from the northern edge of Long Valley caldera towards the Bodie Hills and is bounded by the Cowtrack Mountains on the east and the Sierra Nevada on the west. The Mono-Inyo Craters volcanic chain forms a north-trending zone of volcanic vents extending from the west moat of the Long Valley caldera to Mono Lake. The Hartley Springs fault transects the southern Mono Craters-Inyo Domes area between the western part of the Long Valley caldera and June Lake. Stratigraphic data suggest that a series of strong earthquakes occurred during the North Mono-Inyo eruption sequence of ~1350 A.D. The spatial and temporal proximity between Hartley Springs Fault motion and the North Mono-Inyo eruption sequence suggests a possible relation between seismic events and eruptions. We investigate the interactions between slip along the Hartley Springs fault and dike intrusion beneath the Mono-Inyo craters using a three-dimensional finite element model of the Mono Basin. We employ a realistic representation of the Basin that includes topography, vertical and lateral heterogeneities of the crust, contact relations between fault planes, and a physical model of the pressure required to propagate the dike. We estimate (a) the distribution of Coulomb stress changes to study the influence of dike intrusion on Hartley Springs fault, and (b) the local stress and volumetric dilatation changes to understand how fault slip may influence the propagation of a dike towards the surface.
Jie, Lin; Shinya, Akikazu; Lassila, Lippo V J; Vallittu, Pekka K
2013-01-01
Pre-tensioned construction material is utilized in engineering applications of high strength demands. The purpose of this study was to evaluate the effect of the pre-tensioning fibers of fiber-reinforced composite (FRC) using three-dimensional finite element (FE) analysis. The 3D FE models of particulate composite resin (CR), FRC and composite resin reinforced with pre-tensioned fibers (PRE-T-FRC) were constructed. The uniaxial three-point bending test was simulated using FE analysis to calculate the principal stress distribution. In the FRC and PRE-T-FRC, stresses were higher than CR, and they were located in the fiber. However, the maximum principal stress value at the composite of PRE-T-FRC was lower than the FRC and CR. Composite resin reinforced with pre-tensioned fibers was advantageous for stress distribution and lowering the stress at the composite itself. Experimental studies on physical properties of pre-tensioned FRC are encouraged to be conducted.
Xu, Nuo; Lei, Xue; Yang, Xiaoli; Li, Xinhui; Ge, Zhenlin
2018-04-01
Objective: to compare canine tooth stress distribution condition during maxillary canine tooth distalization by different accessories of bracket-free invisible orthodontics technology after removal of maxillary first premolar, and provide basis for clinical design of invisible orthodontics technology. Method: CBCT scanning image of a patient with individual normal occlusion was adopted, Mimics, Geomagic and ProlE software were used for establishing three-dimensional models of maxilla, maxillary dentition, parodontium, invisible orthodontics appliance and accessories, ANSYS WORKBENCH was utilized as finite element analysis tools for analyzing stress distribution and movement pattern of canine tooth and parodontium when canine tooth was equipped with power arm and vertical rectangle accessory. Meanwhile, canine tooth none-accessory design group was regarded as a control. Result: teeth had even bistal surface stress distribution in the power arm group; stress was concentrated on distal tooth neck, and the stress was gradually deviated to mesial-labial side and distal lingual side in vertical rectangle group and none-accessory group. Conclusion: teeth tend to move as a whole in the Power arm group, vertical rectangle group has lower tooth gradient compared with the none-accessory group, teeth are inclined for movement in the none-accessory group, and canine teeth tend to rotate to the distal lingual side.
Miura, Shoko; Kasahara, Shin; Yamauchi, Shinobu; Egusa, Hiroshi
2017-06-01
The purpose of this study were: to perform stress analyses using three-dimensional finite element analysis methods; to analyze the mechanical stress of different framework designs; and to investigate framework designs that will provide for the long-term stability of both cantilevered fixed partial dentures (FPDs) and abutment teeth. An analysis model was prepared for three units of cantilevered FPDs that assume a missing mandibular first molar. Four types of framework design (Design 1, basic type; Design 2, framework width expanded buccolingually by 2 mm; Design 3, framework height expanded by 0.5 mm to the occlusal surface side from the end abutment to the connector area; and Design 4, a combination of Designs 2 and 3) were created. Two types of framework material (yttrium-oxide partially stabilized zirconia and a high precious noble metal gold alloy) and two types of abutment material (dentin and brass) were used. In the framework designs, Design 1 exhibited the highest maximum principal stress value for both zirconia and gold alloy. In the abutment tooth, Design 3 exhibited the highest maximum principal stress value for all abutment teeth. In the present study, Design 4 (the design with expanded framework height and framework width) could contribute to preventing the concentration of stress and protecting abutment teeth. © 2017 Eur J Oral Sci.
Guodong Liu
2013-01-01
Full Text Available Modular pebble-bed nuclear reactor (MPBNR technology is promising due to its attractive features such as high fuel performance and inherent safety. Particle motion of fuel and graphite pebbles is highly associated with the performance of pebbled-bed modular nuclear reactor. To understand the mechanism of pebble’s motion in the reactor, we numerically studied the influence of number ratio of fuel and graphite pebbles, funnel angle of the reactor, height of guide ring on the distribution of pebble position, and velocity by means of discrete element method (DEM in a two-dimensional MPBNR. Velocity distributions at different areas of the reactor as well as mixing characteristics of fuel and graphite pebbles were investigated. Both fuel and graphite pebbles moved downward, and a uniform motion was formed in the column zone, while pebbles motion in the cone zone was accelerated due to the decrease of the cross sectional flow area. The number ratio of fuel and graphite pebbles and the height of guide ring had a minor influence on the velocity distribution of pebbles, while the variation of funnel angle had an obvious impact on the velocity distribution. Simulated results agreed well with the work in the literature.
Junjie Zeng
2018-03-01
Full Text Available Fiber-reinforced polymer (FRP jacketing/wrapping has become an attractive strengthening technique for concrete columns. Wrapping an existing concrete column with continuous FRP jackets with the fiber in the jacket being oriented in the hoop direction is referred to as FRP full wrapping strengthening technique. In practice, however, strengthening concrete columns with vertically discontinuous FRP strips is also favored and this technique is referred to as FRP partial wrapping strengthening technique. Existing research has demonstrated that FRP partial wrapping strengthening technique is a promising and economical alternative to the FRP full wrapping strengthening technique. Although extensive experimental investigations have hitherto been conducted on partially FRP-confined concrete columns, the confinement mechanics of confined concrete in partially FRP-confined circular columns remains unclear. In this paper, an experimental program consisting of fifteen column specimens was conducted and the test results were presented. A reliable three-dimensional (3D finite element (FE approach for modeling of partially FRP-confined circular columns was established. In the proposed FE approach, an accurate plastic-damage model for concrete under multiaxial compression is employed. The accuracy of the proposed FE approach was verified by comparisons between the numerical results and the test results. Numerical results from the verified FE approach were then presented to gain an improved understanding of the behavior of confined concrete in partially FRP-confined concrete columns.
Wu, B; Wiekenkamp, I; Sun, Y; Fisher, A S; Clough, R; Gottselig, N; Bogena, H; Pütz, T; Brüggemann, N; Vereecken, H; Bol, R
2017-11-01
Quantification and evaluation of elemental distribution in forested ecosystems are key requirements to understand element fluxes and their relationship with hydrological and biogeochemical processes in the system. However, datasets supporting such a study on the catchment scale are still limited. Here we provide a dataset comprising spatially highly resolved distributions of 39 elements in soil profiles of a small forested headwater catchment in western Germany () to gain a holistic picture of the state and fluxes of elements in the catchment. The elements include both plant nutrients and other metals and metalloids that were predominately derived from lithospheric or anthropogenic inputs, thereby allowing us to not only capture the nutrient status of the catchment but to also estimate the functional development of the ecosystem. Soil samples were collected at high lateral resolution (≤60 m), and element concentrations were determined vertically for four soil horizons (L/Of, Oh, A, B). From this, a three-dimensional view of the distribution of these elements could be established with high spatial resolution on the catchment scale in a temperate natural forested ecosystem. The dataset can be combined with other datasets and studies of the TERENO (Terrestrial Environmental Observatories) Data Discovery Portal () to reveal elemental fluxes, establish relations between elements and other soil properties, and/or as input for modeling elemental cycling in temperate forested ecosystems. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.
Moreira, Wagner; Hermann, Caio; Pereira, Jucélio Tomás; Balbinoti, Jean Anacleto; Tiossi, Rodrigo
2013-10-01
The purpose of this study was to evaluate the mechanical behavior of two different straight prosthetic abutments (one- and two-piece) for external hex butt-joint connection implants using three-dimensional finite element analysis (3D-FEA). Two 3D-FEA models were designed, one for the two-piece prosthetic abutment (2 mm in height, two-piece mini-conical abutment, Neodent) and another one for the one-piece abutment (2 mm in height, Slim Fit one-piece mini-conical abutment, Neodent), with their corresponding screws and implants (Titamax Ti, 3.75 diameter by 13 mm in length, Neodent). The model simulated the single restoration of a lower premolar using data from a computerized tomography of a mandible. The preload (20 N) after torque application for installation of the abutment and an occlusal loading were simulated. The occlusal load was simulated using average physiological bite force and direction (114.6 N in the axial direction, 17.1 N in the lingual direction and 23.4 N toward the mesial at an angle of 75° to the occlusal plan). The regions with the highest von Mises stress results were at the bottom of the initial two threads of both prosthetic abutments that were tested. The one-piece prosthetic abutment presented a more homogeneous behavior of stress distribution when compared with the two-piece abutment. Under the simulated chewing loads, the von Mises stresses for both tested prosthetic-abutments were within the tensile strength values of the materials analyzed which thus supports the clinical use of both prosthetic abutments.
M. Nawaz
Full Text Available In this article, we developed a computer code of Galerikan Finite Element method (GFEM for three dimensional flow equations of nano-plasma fluid (blood in the presence of uniform applied magnetic field when Hall and ion slip current are significant. Lorentz force is calculated through generalized Ohm’s law with Maxwell equations. A series of numerical simulations are carried out to search ηmax and algebraic equations are solved by Gauss-Seidel method with simulation tolerance 10-8. Simulated results for special case have an excellent agreement with the already published results. Velocity components and temperature of the nano-plasma (blood are influenced significantly by the inclusion of nano-particles of Copper (Cu and Silver (Ag. Heat enhancement is observed when copper and silver nonmagnetic nanoparticles are used instead of simple base fluid (conventional fluid. Radiative nature of nano-plasma in the presence of magnetic field causes a decrease in the temperature due to the transfer of heat by the electromagnetic waves. In contrast to this, due to heat dissipated by Joule heating and viscous dissipation phenomena, temperature of nano-plasmaincreases as thermal radiation parameter is increased. Thermal boundary layer thickness can be controlled by using radiative fluid instead of non-radiative fluid. Momentum boundary layer thickness can be reduced by increasing the intensity of the applied magnetic field. Temperature of plasma in the presence magnetic field is higher than the plasma in the absence of magnetic field. Keywords: Nanofluid, Grid independent study, Convergence, Error analysis, Skin friction, Joule heating, Viscous dissipation, Hall and ion currents
Hutula, D.N.; Wiancko, B.E.
1980-03-01
ACCEPT is a three-dimensional finite element computer program for analysis of large-deformation elastic-plastic-creep response of Zircaloy tubes subjected to temperature, surface pressures, and axial force. A twenty-mode, tri-quadratic, isoparametric element is used along with a Zircaloy materials model. A linear time-incremental procedure with residual force correction is used to solve for the time-dependent response. The program features an algorithm which automatically chooses the time step sizes to control the accuracy and numerical stability of the solution. A contact-separation capability allows modeling of interaction of reactor fuel rod cladding with fuel pellets or external supports
Fernandes, A.
1991-01-01
A method to solve three dimensional neutron transport equation and it is based on the original work suggested by J.K. Fletcher (42, 43). The angular dependence of the flux is approximated by associated Legendre functions and the finite element method is applied to the space components is presented. When the angular flux, the scattering cross section and the neutrons source are expanded in associated Legendre functions, the first order neutron transport equation is reduced to a coupled set of second order diffusion like equations. These equations are solved in an iterative way by the finite element method to the moments. (author)
Biffle, J.H.; Blanford, M.L.
1994-05-01
JAC2D is a two-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 equations. The method is implemented in a two-dimensional setting with various methods for accelerating convergence. Sliding interface logic is also implemented. A four-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
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
Doszhanova, A.A.; Zhunusbekov, A.M.; Ismagambetov, M.U.; Sapargaliev, A.A.; Sapargaliev, E.A.
2004-01-01
The two-dimensional electrostatic corpuscular electronics elements with an average plane (TD ECEE with AP) are considered. The basic differential equations describing a trajectory and time of flight of charged particles in TD ECEE with AP are received. These equations can form a basis for creation of the theory of spatial and time structure of a stream of the charged particles in anyone TD ECEE with AP. (author)
Krishna Chaitanya Kanneganti; Dileep Nag Vinnakota; Srinivas Rao Pottem; Mahesh Pulagam
2018-01-01
Purpose: The purpose of this study is to compare the effect of implant-abutment connections, abutment angulations, and screw lengths on screw loosening (SL) of preloaded abutment using three dimensional (3D) finite element analysis. Materials and Methods: 3D models of implants (conical connection with hex/trilobed connections), abutments (straight/angulated), abutment screws (short/long), and crown and bone were designed using software Parametric Technology Corporation Creo and assembled t...
Wallroth, C.F.; Marsh, N.I.; Miller, C.M.; Saurwein, J.J.; Smith, T.L.
1979-11-01
A robotic device has been developed for dimensional and visual inspection of irradiated HTGR core components. The robot consists of a rotary table and a two-finger probe, driven by stepping motors, and four remotely controlled television cameras. Automated operation is accomplished via minicomputer control. A total of 51 irradiated fuel and reflector elements were inspected at a fraction of the time and cost required for conventional methods
1978-01-01
A three-dimensional finite elements analysis is reported of the nonlinear behavior of PCRV subjected to internal pressure by comparing calculated results with test results. As the first stage, an analysis considering the nonlinearity of cracking in concrete was attempted. As a result, it is found possible to make an analysis up to three times the design pressure (50 kg/sqcm), and calculated results agree well with test results.
Chen, Shijia; Guillemot, Gildas; Gandin, Charles-André
2016-01-01
Solidification grain structure has significant impact on the final properties of welded parts using fusion welding processes. Direct simulation of grain structure at industrial scale is yet rarely reported in the literature and remains a challenge. A three-dimensional (3D) coupled Cellular Automaton (CA) – Finite Element (FE) model is presented that predicts the grain structure formation during multiple passes Gas Tungsten Arc Welding (GTAW) and Gas Metal Arc Welding (GMAW). The FE model is established in a level set (LS) approach that tracks the evolution of the metal-shielding gas interface due to the addition of metal. The FE method solves the mass, energy and momentum conservation equations for the metal plus shielding gas system based on an adaptive mesh (FE mesh). Fields are projected in a second FE mesh, named CA mesh. A CA grid made of a regular lattice of cubic cells is created to overlay the fixed CA mesh. The CA model based on the CA grid simulates the melting and growth of the grain boundaries in the liquid pool. In order to handle large computational domains while keeping reasonable computational costs, parallel computations and dynamic strategies for the allocation/deallocation of the CA grid are introduced. These strategies correspond to significant optimizations of the computer memories that are demonstrated. The 3D CAFE model is first applied to the simple configuration of single linear passes by GTAW of a duplex stainless steel URANUS 2202. It is then applied to a more persuasive example considering GMAW in spray transfer mode during multiple passes to fill a V-groove chamfer. Simulations reveal the possibility to handle domains with millions of grains in representative domain sizes while following the formation of textures that result from the growth competition among columnar grains. -- Graphical abstract: Simulated 3D grain structure (3D CAFE model) for GTAW multiple linear passes at the surface of a duplex stainless steel (URANUS 22002
Kaur, Ravinder
2009-01-01
The refugee, in India's Partition history, appears as an enigmatic construct - part pitiful, part heroic, though mostly shorn of agency - representing the surface of the human tragedy of Partition. Yet this archetype masks the undercurrent of social distinctions that produced hierarchies of post...
Nazco, Julio
2009-01-01
The main objective of this work is presented through case studies discussed in our institution, which has brought several advantages to use Planning Three-dimensional beam and cobalt 60 Theraplan Plus System, showing thus qualitative and quantitative (clinical case of lung cancer) that have achieved by the use of this new tool. To illustrate the above 5 clinical cases are chosen belonging to 5 different sites (endometrium, prostate, lung, pineal gland and brainstem) and are presented in each case the advantages provided by using the Tridimensional Planning System. (Author)
Avinash Kumar
2017-01-01
Full Text Available Objectives: To analyze three-dimensional effects of stress distribution and displacement on the craniofacial structures, following the application of forces from Nitanium Palatal Expander 2 (NPE2 and Hyrax appliance in early mixed dentition period using finite element analysis. Materials and Methods: Three-dimensional finite element models of the young dried human skull, NPE2 and Hyrax were constructed, and the initial activation of the expanders was simulated to carry out the analysis and to evaluate the von misses stresses and displacement on the craniofacial structures. Results: Both the models demonstrated the highest stresses at the mid-palatal suture, with maximum posterior dislocation. The inferior nasal floor showed highest downward displacement and point A showed outward, backward, and upward displacement in both the models. The pattern of stress distribution was almost similar in both the groups, but NPE2 revealed lower magnitude stresses than Hyrax. The cusp of the erupting canine and the mesiobuccal cusp of the second molar showed outward, backward, and downward displacement signifying eruption pattern following maxillary expansion. Conclusions: Nickel titanium palatal expander-2 and Hyrax produced similar stress pattern in early mixed dentition period finite element model. We conclude from this finite element method study that NPE2 is equally effective as Hyrax when used in early mixed dentition period as it exhibits orthopedic nature of expansion with minimal residual stresses in the craniofacial structures.
Parent, Kristin N.; Tang, Jinghua; Cardone, Giovanni; Gilcrease, Eddie B.; Janssen, Mandy E.; Olson, Norman H.; Casjens, Sherwood R.; Baker, Timothy S.
2014-01-01
CUS-3 is a short-tailed, dsDNA bacteriophage that infects serotype K1 Escherichia coli. We report icosahedrally averaged and asymmetric, three-dimensional, cryo-electron microscopic reconstructions of the CUS-3 virion. Its coat protein structure adopts the “HK97-fold” shared by other tailed phages and is quite similar to that in phages P22 and Sf6 despite only weak amino acid sequence similarity. In addition, these coat proteins share a unique extra external domain (“I-domain”), suggesting that the group of P22-like phages has evolved over a very long time period without acquiring a new coat protein gene from another phage group. On the other hand, the morphology of the CUS-3 tailspike differs significantly from that of P22 or Sf6, but is similar to the tailspike of phage K1F, a member of the extremely distantly related T7 group of phages. We conclude that CUS-3 obtained its tailspike gene from a distantly related phage quite recently. - Highlights: • Asymmetric and symmetric three-dimensional reconstructions of phage CUS-3 are presented. • CUS-3 major capsid protein has a conserved I-domain, which is found in all three categories of “P22-like phage”. • CUS-3 has very different tailspike receptor binding domain from those of P22 and Sf6. • The CUS-3 tailspike likely was acquired by horizontal gene transfer
Parent, Kristin N., E-mail: kparent@msu.edu [Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0378 (United States); Tang, Jinghua; Cardone, Giovanni [Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0378 (United States); Gilcrease, Eddie B. [University of Utah School of Medicine, Division of Microbiology and Immunology, Department of Pathology, Salt Lake City, UT 84112 (United States); Janssen, Mandy E.; Olson, Norman H. [Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0378 (United States); Casjens, Sherwood R., E-mail: sherwood.casjens@path.utah.edu [University of Utah School of Medicine, Division of Microbiology and Immunology, Department of Pathology, Salt Lake City, UT 84112 (United States); Baker, Timothy S., E-mail: tsb@ucsd.edu [Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0378 (United States); University of California, San Diego, Division of Biological Sciences, La Jolla, CA, 92093 (United States)
2014-09-15
CUS-3 is a short-tailed, dsDNA bacteriophage that infects serotype K1 Escherichia coli. We report icosahedrally averaged and asymmetric, three-dimensional, cryo-electron microscopic reconstructions of the CUS-3 virion. Its coat protein structure adopts the “HK97-fold” shared by other tailed phages and is quite similar to that in phages P22 and Sf6 despite only weak amino acid sequence similarity. In addition, these coat proteins share a unique extra external domain (“I-domain”), suggesting that the group of P22-like phages has evolved over a very long time period without acquiring a new coat protein gene from another phage group. On the other hand, the morphology of the CUS-3 tailspike differs significantly from that of P22 or Sf6, but is similar to the tailspike of phage K1F, a member of the extremely distantly related T7 group of phages. We conclude that CUS-3 obtained its tailspike gene from a distantly related phage quite recently. - Highlights: • Asymmetric and symmetric three-dimensional reconstructions of phage CUS-3 are presented. • CUS-3 major capsid protein has a conserved I-domain, which is found in all three categories of “P22-like phage”. • CUS-3 has very different tailspike receptor binding domain from those of P22 and Sf6. • The CUS-3 tailspike likely was acquired by horizontal gene transfer.
Barbosa, R.F.; Anjos, M.J.; Jesus, E.F.O. de; Lopes, R.T.; Oliveira, L.F. de; Carmo, M.G.T. do; Rocha, M.S.; Martinez, A.M.B.
2008-01-01
Full text: There are few methods available to measure the spatial (two (three)-dimensional) elemental distribution in animal brain. X-Ray Microfluorescence with Synchrotron Radiation is a multielemental mapping technique, which was used in this work to determine the two-dimensional maps of phosphorous (P), chlorine (Cl), potassium (K), iron (Fe), copper (Cu) and zinc (Zn) in coronal sections of adult (60 days old) and middle aged (20 months old) female (n = 4) and male (n = 4) Wistar rats. The measurements were carried out at the XRF beam line at the Synchrotron Light National Laboratory (Campinas, Brazil). A two-dimensional scanning was performed in order to study the tendency of elemental concentration variation and the elemental distribution. The acquisition time for each pixel was 10 s/step and the step size was 300 μm/step in both directions. It was observed that P levels decreased with advancing age in female rats, but, on the other hand, these levels increased with advancing age in male rats. K, Fe and Cu levels increased in female and male middle-aged rats in the same ways as P and Cl levels (only in male animals). In addition to this, Fe levels were higher in females rats than males ones. However, in relation to P and K distributions, they were homogeneous in the entire brain section, independently of the gender and age. Cl distribution was more pronounced in cortical areas, hippocampus and thalamus for all the animals studied, except for the middle-aged female rats. Fe distribution was more conspicuous in the thalamus, hypothalamus and cortical area. Moreover, Zn distributions are in good concern with the results reported by the literature, being more intense in the hippocampus. Our results showed that an increase of Fe, Cu and Zn with aging can be related to the development of some neurodegenerative disorders, since the literature reports an increase of these elements in Parkinson disease, Alzheimer disease and Wilson Disease. Therefore, we can see that
Bulia, Isabella Longhi; Enzweiler, Jacinta, E-mail: isabellalonghi@ige.unicamp.br, E-mail: jacinta@ige.unicamp.br [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Instituto de Geociencias
2015-07-01
The composition of groundwaters results mainly from water-rock reactions within aquifers. Among the various constituents of water, the rare earth elements (REE) and uranium can serve as tracers of geochemical processes and hydrological flow paths. The main objective of this study was to associate the chemical composition of groundwaters extracted from three distinct aquifer systems (crystalline, diabase and sedimentary) with that of the respective hosts rocks. The area of the study is located at the campus of University of Campinas (Campinas, SP). Samples of groundwater collected from four tubular wells were used to determine physicochemical parameters, major ions and trace elements, including the REE. The results confirm that the water of two wells (IMECC and IB) is predominantly influenced by the crystalline and diabase aquifers, while the other two (GM and FEF) by the sedimentary aquifer. Both the individual and normalized REE values of the four wells are distinct from each other, pointing to the heterogeneity of the local geology. The uranium concentration in the water of one well (GM) exceeded the guideline value for this element in drinking water. The U probably results from the oxidative dissolution of U-bearing phases in the sedimentary aquifer. However, the hydrochemical modeling indicated Ca{sub 2}UO{sub 2}(CO{sub 3}){sub 3} and CaUO{sub 2}(CO{sub 3}){sub 2}{sup 2-} as the major U dissolved species, which are considered non-toxic and non-bioavailable according to literature data. (author)
Yihaa Roodhiyah, Lisa’; Tjong, Tiffany; Nurhasan; Sutarno, D.
2018-04-01
The late research, linear matrices of vector finite element in two dimensional(2-D) magnetotelluric (MT) responses modeling was solved by non-sparse direct solver in TE mode. Nevertheless, there is some weakness which have to be improved especially accuracy in the low frequency (10-3 Hz-10-5 Hz) which is not achieved yet and high cost computation in dense mesh. In this work, the solver which is used is sparse direct solver instead of non-sparse direct solverto overcome the weaknesses of solving linear matrices of vector finite element metod using non-sparse direct solver. Sparse direct solver will be advantageous in solving linear matrices of vector finite element method because of the matrix properties which is symmetrical and sparse. The validation of sparse direct solver in solving linear matrices of vector finite element has been done for a homogen half-space model and vertical contact model by analytical solution. Thevalidation result of sparse direct solver in solving linear matrices of vector finite element shows that sparse direct solver is more stable than non-sparse direct solver in computing linear problem of vector finite element method especially in low frequency. In the end, the accuracy of 2D MT responses modelling in low frequency (10-3 Hz-10-5 Hz) has been reached out under the efficient allocation memory of array and less computational time consuming.
Kogure, Takahisa; Takagi, Masamichi; Ohta, Akinori
2005-01-01
The ALK2 gene, encoding one of the n-alkane-hydroxylating cytochromes P450 in Candida maltosa, is induced by n-alkanes and a peroxisome proliferator, clofibrate. Deletion analysis of this gene's promoter revealed two cis-acting elements-an n-alkane-responsive element (ARE2) and a clofibrate-responsive element (CRE2)-that partly overlap in sequence but have distinct functions. ARE2-mediated activation responded to n-alkanes but not to clofibrate and was repressed by glucose. CRE2-mediated activation responded to polyunsaturated fatty acids and steroid hormones as well as to peroxisome proliferators but not to n-alkanes, and it was not repressed by glucose. Both elements mediated activation by oleic acid. Mutational analysis demonstrated that three CCG sequences in CRE2 were critical to the activation by clofibrate as well as to the in vitro binding of a specific protein to this element. These findings suggest that ALK2 is induced by peroxisome proliferators and steroid hormones through a specific CRE2-mediated regulatory mechanism
Araujo, Vitor; Viana, Marcelo
2010-01-01
In this book, the authors present the elements of a general theory for flows on three-dimensional compact boundaryless manifolds, encompassing flows with equilibria accumulated by regular orbits. The book aims to provide a global perspective of this theory and make it easier for the reader to digest the growing literature on this subject. This is not the first book on the subject of dynamical systems, but there are distinct aspects which together make this book unique. Firstly, this book treats mostly continuous time dynamical systems, instead of its discrete counterpart, exhaustively treated
Test Functions for Three-Dimensional Control-Volume Mixed Finite-Element Methods on Irregular Grids
Naff, R. L; Russell, T. F; Wilson, J. D
2000-01-01
.... For control-volume mixed finite-element methods, vector shape functions are used to approximate the distribution of velocities across cells and vector test functions are used to minimize the error...
Jo, Jong Chull; Shin, Won Ky [Korea Institute of Nuclear Safety, Taejon (Korea, Republic of)
1997-12-31
This paper presents an effective and simple procedure for the simulation of the motion of the solid-liquid interfacial boundary and the transient temperature field during phase change process. To accomplish this purpose, an iterative implicit solution algorithm has been developed by employing the dual reciprocity boundary element method. The dual reciprocity boundary element approach provided in this paper is much simpler than the usual boundary element method applying a reciprocity principle and an available technique for dealing with domain integral of boundary element formulation simultaneously. The effectiveness of the present analysis method have been illustrated through comparisons of the calculation results of an example with its semi-analytical or other numerical solutions where available. 22 refs., 3 figs. (Author)
Jo, Jong Chull; Shin, Won Ky
1997-01-01
This paper presents an effective and simple procedure for the simulation of the motion of the solid-liquid interfacial boundary and the transient temperature field during phase change process. To accomplish this purpose, an iterative implicit solution algorithm has been developed by employing the dual reciprocity boundary element method. The dual reciprocity boundary element approach provided in this paper is much simpler than the usual boundary element method applying a reciprocity principle and an available technique for dealing with domain integral of boundary element formulation simultaneously. The effectiveness of the present analysis method have been illustrated through comparisons of the calculation results of an example with its semi-analytical or other numerical solutions where available
Jo, Jong Chull; Shin, Won Ky [Korea Institute of Nuclear Safety, Taejon (Korea, Republic of)
1998-12-31
This paper presents an effective and simple procedure for the simulation of the motion of the solid-liquid interfacial boundary and the transient temperature field during phase change process. To accomplish this purpose, an iterative implicit solution algorithm has been developed by employing the dual reciprocity boundary element method. The dual reciprocity boundary element approach provided in this paper is much simpler than the usual boundary element method applying a reciprocity principle and an available technique for dealing with domain integral of boundary element formulation simultaneously. The effectiveness of the present analysis method have been illustrated through comparisons of the calculation results of an example with its semi-analytical or other numerical solutions where available. 22 refs., 3 figs. (Author)
Yu, Cong; Malakpoor, Kamyar; Huyghe, Jacques M.
2018-01-01
A hydrogel is a cross-linked polymer network with water as solvent. Industrially widely used superabsorbent polymers (SAP) are partially neutralized sodium polyacrylate hydrogels. The extremely large degree of swelling is one of the most distinctive characteristics of such hydrogels, as the volume
Vampola, Tomáš; Horáček, Jaromír; Laukkanen, Anne-Maria; Švec, Jan G
2015-04-01
Resonance frequencies of the vocal tract have traditionally been modelled using one-dimensional models. These cannot accurately represent the events in the frequency region of the formant cluster around 2.5-4.5 kHz, however. Here, the vocal tract resonance frequencies and their mode shapes are studied using a three-dimensional finite element model obtained from computed tomography measurements of a subject phonating on vowel [a:]. Instead of the traditional five, up to eight resonance frequencies of the vocal tract were found below the prominent antiresonance around 4.7 kHz. The three extra resonances were found to correspond to modes which were axially asymmetric and involved the piriform sinuses, valleculae, and transverse vibrations in the oral cavity. The results therefore suggest that the phenomenon of speaker's and singer's formant clustering may be more complex than originally thought.
Kubrak, Elżbieta; Kubrak, Janusz; Rowiński, Paweł
2013-02-01
One-dimensional model for vertical profiles of longitudinal velocities in open-channel flows is verified against laboratory data obtained in an open channel with artificial plants. Those plants simulate Canadian waterweed which in nature usually forms dense stands that reach all the way to the water surface. The model works particularly well for densely spaced plants.
Nakamura, Yoshinori; Kanbara, Ryo; Ochiai, Kent T; Tanaka, Yoshinobu
2014-10-01
The mechanical evaluation of the function of partial removable dental prostheses with 3-dimensional finite element modeling requires the accurate assessment and incorporation of soft tissue behavior. The differential behaviors of the residual ridge mucosa and periodontal ligament tissues have been shown to exhibit nonlinear displacement. The mathematic incorporation of known values simulating nonlinear soft tissue behavior has not been investigated previously via 3-dimensional finite element modeling evaluation to demonstrate the effect of prosthesis design on the supporting tissues. The purpose of this comparative study was to evaluate the functional differences of 3 different partial removable dental prosthesis designs with 3-dimensional finite element analysis modeling and a simulated patient model incorporating known viscoelastic, nonlinear soft tissue properties. Three different designs of distal extension removable partial dental prostheses were analyzed. The stress distributions to the supporting abutments and soft tissue displacements of the designs tested were calculated and mechanically compared. Among the 3 dental designs evaluated, the RPI prosthesis demonstrated the lowest stress concentrations on the tissue supporting the tooth abutment and also provided wide mucosa-borne areas of support, thereby demonstrating a mechanical advantage and efficacy over the other designs evaluated. The data and results obtained from this study confirmed that the functional behavior of partial dental prostheses with supporting abutments and soft tissues are consistent with the conventional theories of design and clinical experience. The validity and usefulness of this testing method for future applications and testing protocols are shown. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.
Young Soo Kim
2013-05-01
Full Text Available Background To construct a sophisticated three-dimensionalframework, numerousmodifications have been reported in the literature. However, mostsurgeons have paid little attentionto the anatomical configuration of the concha and more to its deepness and hollowness,leading to unsatisfactory outcomes.Methods For a configuration ofthe concha thatis definitely anatomical,the authorfurtherdeveloped and employed the conchal bowl element,which has been used by severalsurgeonsalthough the results have not been published elsewhere. The author constructed the conchalbowl element in one of three patterns according to the amount of available cartilages: oneblock,two-pieces, or a cymba bowl element only. A total of 20 patients underwent auricularreconstruction using a costal cartilage framework between 2009 and 2012. The 8 earliestreconstructionswere performedwithout a conchal bowl element and the latter 12with a conchalbowl element. The patientswere followed up for more than 1 year. The aesthetic resultswerescored by evaluating characteristicsinvolving the stability ofthe crus helicis,the conchal definition, and the smoothness ofthe helical curve.Results The earsreconstructed earlywithout a conchal bowl elementshowed a shallowandone or two incompletely separated concha with an obliterated cymba conchal space. Theyalso did not have a realistic orsmooth curve ofthe helix because of an unstable crus helicis.However, earsreconstructed laterwith the concha bowl elementshowed a definite crus helicis,deep cymba conchalspace, and smooth helical curve.Conclusions The construction of the conchal bowl element is simple, not time-consumingprocedure. It is suggested that the conchal bowl element must be constructed and attachedto themain framework for natural configuration ofthe reconstructed ear.
Goto, Akiko; Hokura, Akiko; Nakai, Izumi
2008-01-01
The forensic discrimination of adhesive cloth tapes often used in crimes was developed using a high-energy energy-dispersive X-ray fluorescence spectrometer with 3-dimensional polarization optics. The best measurement condition for discrimination of the tape was as follows: secondary targets, Rh and Al 2 O 3 ; measurement time, 300 s for Rh and 600 s for Al 2 O 3 ; 14 elements (Ca, Ti, Cr, Mn, Fe, Ni, Zn, Sr, Zr, Nb, Mo, Sb, Ba and Pb) were used for discrimination. It is found that the combined information of yarn density and the XRF peak intensity of the 14 elements successfully discriminated 29 out of 31 samples, of which 2 probably had the same origin. This technique is useful for forensic analysis, because it is nondestructive, rapid and easy. Therefore, it can be applied to actual forensic identification. (author)
Hallquist, J.O.
1982-02-01
This revised report provides an updated user's manual for DYNA2D, an explicit two-dimensional axisymmetric and plane strain finite element code for analyzing the large deformation dynamic and hydrodynamic response of inelastic solids. A contact-impact algorithm permits gaps and sliding along material interfaces. By a specialization of this algorithm, such interfaces can be rigidly tied to admit variable zoning without the need of transition regions. Spatial discretization is achieved by the use of 4-node solid elements, and the equations-of motion are integrated by the central difference method. An interactive rezoner eliminates the need to terminate the calculation when the mesh becomes too distorted. Rather, the mesh can be rezoned and the calculation continued. The command structure for the rezoner is described and illustrated by an example.
Igumnov Leonid
2015-01-01
Full Text Available The report presents the development of the time-boundary element methodology and a description of the related software based on a stepped method of numerical inversion of the integral Laplace transform in combination with a family of Runge-Kutta methods for analyzing 3-D mixed initial boundary-value problems of the dynamics of inhomogeneous elastic and poro-elastic bodies. The results of the numerical investigation are presented. The investigation methodology is based on direct-approach boundary integral equations of 3-D isotropic linear theories of elasticity and poroelasticity in Laplace transforms. Poroelastic media are described using Biot models with four and five base functions. With the help of the boundary-element method, solutions in time are obtained, using the stepped method of numerically inverting Laplace transform on the nodes of Runge-Kutta methods. The boundary-element method is used in combination with the collocation method, local element-by-element approximation based on the matched interpolation model. The results of analyzing wave problems of the effect of a non-stationary force on elastic and poroelastic finite bodies, a poroelastic half-space (also with a fictitious boundary and a layered half-space weakened by a cavity, and a half-space with a trench are presented. Excitation of a slow wave in a poroelastic medium is studied, using the stepped BEM-scheme on the nodes of Runge-Kutta methods.
Comet, Itys; Schuettengruber, Bernd; Sexton, Tom
2011-01-01
to insulate genes from regulatory elements or to take part in long-distance interactions. Using a high-resolution chromatin conformation capture (H3C) method, we show that the Drosophila gypsy insulator behaves as a conformational chromatin border that is able to prohibit contacts between a Polycomb response...... element (PRE) and a distal promoter. On the other hand, two spaced gypsy elements form a chromatin loop that is able to bring an upstream PRE in contact with a downstream gene to mediate its repression. Chromatin immunoprecipitation (ChIP) profiles of the Polycomb protein and its associated H3K27me3...... histone mark reflect this insulator-dependent chromatin conformation, suggesting that Polycomb action at a distance can be organized by local chromatin topology....
Morris, J; Johnson, S
2007-12-03
The Distinct Element Method (also frequently referred to as the Discrete Element Method) (DEM) is a Lagrangian numerical technique where the computational domain consists of discrete solid elements which interact via compliant contacts. This can be contrasted with Finite Element Methods where the computational domain is assumed to represent a continuum (although many modern implementations of the FEM can accommodate some Distinct Element capabilities). Often the terms Discrete Element Method and Distinct Element Method are used interchangeably in the literature, although Cundall and Hart (1992) suggested that Discrete Element Methods should be a more inclusive term covering Distinct Element Methods, Displacement Discontinuity Analysis and Modal Methods. In this work, DEM specifically refers to the Distinct Element Method, where the discrete elements interact via compliant contacts, in contrast with Displacement Discontinuity Analysis where the contacts are rigid and all compliance is taken up by the adjacent intact material.
Kita, Toshihiro
2005-01-01
A simple system consisting of a second-order lag element (a damped linear pendulum) and two first-order lag elements with piecewise-linear static feedback that has been derived from a power system model is presented. It exhibits chaotic behavior for a wide range of parameter values. The analysis of the bifurcations and the chaotic behavior are presented with qualitative estimation of the parameter values for which the chaotic behavior is observed. Several characteristics like scalability of the attractor and globality of the attractor-basin are also discussed
A retrospective and prospective survey of three-dimensional transport calculations
Nakahara, Yasuaki
1985-01-01
A retrospective survey is made on the three-dimensional radiation transport calculations. Introduction is given to computer codes based on the distinctive numerical methods such as the Monte Carlo, Direct Integration, Ssub(n) and Finite Element Methods to solve the three-dimensional transport equations. Prospective discussions are made on pros and cons of these methods. (author)
Singh, Gurdeep; Saxena, Ravindra K.; Pandey, Sunil
2018-04-01
The aim of this study to developed a 3-D thermal finite element model for dissimilar material welding of AISI-304 stainless steel and copper. Welding of similar material is widely studied using experimental and numerical methods but the problem becomes trivial for the welding of dissimilar materials especially in ferrous and nonferrous materials. Finite element analysis of dissimilar material welding is a cost-effective method for the understanding and analysis of the process. The finite element analysis has been performed to predict the heat affected zone and temperature distribution in AISI-304 stainless steel and copper dissimilar weldment using MSC Marc 2017®. Due to the difference in physical properties of these materials the behavior of heat affected zone and temperature distribution are perceived to be different. To verify the accuracy of the thermal finite element model, the welding process was simulated with butt-welded joints having same dimensions and parameters from Attarha and Far [1]. It is found from the study that the heat affected zone is larger in copper weld pads than in AISI 304 stainless steel due to large difference in thermal conductivity of these two weld pads.
Li, Xiaomin; Guo, Xueli; Guo, Haiyan
2018-06-01
Robust numerical models that describe the complex behaviors of risers are needed because these constitute dynamically sensitive systems. This paper presents a simple and efficient algorithm for the nonlinear static and dynamic analyses of marine risers. The proposed approach uses the vector form intrinsic finite element (VFIFE) method, which is based on vector mechanics theory and numerical calculation. In this method, the risers are described by a set of particles directly governed by Newton's second law and are connected by weightless elements that can only resist internal forces. The method does not require the integration of the stiffness matrix, nor does it need iterations to solve the governing equations. Due to these advantages, the method can easily increase or decrease the element and change the boundary conditions, thus representing an innovative concept of solving nonlinear behaviors, such as large deformation and large displacement. To prove the feasibility of the VFIFE method in the analysis of the risers, rigid and flexible risers belonging to two different categories of marine risers, which usually have differences in modeling and solving methods, are employed in the present study. In the analysis, the plane beam element is adopted in the simulation of interaction forces between the particles and the axial force, shear force, and bending moment are also considered. The results are compared with the conventional finite element method (FEM) and those reported in the related literature. The findings revealed that both the rigid and flexible risers could be modeled in a similar unified analysis model and that the VFIFE method is feasible for solving problems related to the complex behaviors of marine risers.
Qinghua, Zhao; Jipeng, Li; Yongxing, Zhang; He, Liang; Xuepeng, Wang; Peng, Yan; Xiaofeng, Wu
2015-04-07
To employ three-dimensional finite element modeling and biomechanical simulation for evaluating the stability and stress conduction of two postoperative internal fixed modeling-multilevel posterior instrumentation ( MPI) and MPI with anterior instrumentation (MPAI) with neck-thoracic vertebral tumor en bloc resection. Mimics software and computed tomography (CT) images were used to establish the three-dimensional (3D) model of vertebrae C5-T2 and simulated the C7 en bloc vertebral resection for MPI and MPAI modeling. Then the statistics and images were transmitted into the ANSYS finite element system and 20N distribution load (simulating body weight) and applied 1 N · m torque on neutral point for simulating vertebral displacement and stress conduction and distribution of motion mode, i. e. flexion, extension, bending and rotating. With a better stability, the displacement of two adjacent vertebral bodies of MPI and MPAI modeling was less than that of complete vertebral modeling. No significant differences existed between each other. But as for stress shielding effect reduction, MPI was slightly better than MPAI. From biomechanical point of view, two internal instrumentations with neck-thoracic tumor en bloc resection may achieve an excellent stability with no significant differences. But with better stress conduction, MPI is more advantageous in postoperative reconstruction.
Kulak, R.F.; Kennedy, J.M.; Belytschko, T.B.; Schoeberle, D.F.
1977-01-01
This paper describes finite-element formulations for the thermal stress analysis of LMFBR structures. The first formulation is applicable to large displacement rotation problems in which the strains are small. For this formulation, a general temperature-dependent constituent relationship is derived from a Gibbs potential and a temperature dependent surface. A second formulation is presented for problems characterized by both large displacement-rotations and large strains. Here a set of large strain hypoelastic-plastic relationships are developed to linearly relate the rate of stress to the rate of deformation. These developments were incorporated into two ANL developed finite-element computer codes: the implicit version of STRAW and the 3D Implicit Structural Analaysis code. A set of problems is presented to validate both the 3D and 2D programs and to illustrate their applicability to a variety of problems. (Auth.)
Sotelo, Julio; Urbina, Jesús; Valverde, Israel; Mura, Joaquín; Tejos, Cristián; Irarrazaval, Pablo; Andia, Marcelo E; Hurtado, Daniel E; Uribe, Sergio
2018-01-01
We propose a 3D finite-element method for the quantification of vorticity and helicity density from 3D cine phase-contrast (PC) MRI. By using a 3D finite-element method, we seamlessly estimate velocity gradients in 3D. The robustness and convergence were analyzed using a combined Poiseuille and Lamb-Ossen equation. A computational fluid dynamics simulation was used to compared our method with others available in the literature. Additionally, we computed 3D maps for different 3D cine PC-MRI data sets: phantom without and with coarctation (18 healthy volunteers and 3 patients). We found a good agreement between our method and both the analytical solution of the combined Poiseuille and Lamb-Ossen. The computational fluid dynamics results showed that our method outperforms current approaches to estimate vorticity and helicity values. In the in silico model, we observed that for a tetrahedral element of 2 mm of characteristic length, we underestimated the vorticity in less than 5% with respect to the analytical solution. In patients, we found higher values of helicity density in comparison to healthy volunteers, associated with vortices in the lumen of the vessels. We proposed a novel method that provides entire 3D vorticity and helicity density maps, avoiding the used of reformatted 2D planes from 3D cine PC-MRI. Magn Reson Med 79:541-553, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.
Pavel A. Akimov
2017-12-01
Full Text Available As is well known, the formulation of a multipoint boundary problem involves three main components: a description of the domain occupied by the structure and the corresponding subdomains; description of the conditions inside the domain and inside the corresponding subdomains, the description of the conditions on the boundary of the domain, conditions on the boundaries between subdomains. This paper is a continuation of another work published earlier, in which the formulation and general principles of the approximation of the multipoint boundary problem of a static analysis of deep beam on the basis of the joint application of the finite element method and the discrete-continual finite element method were considered. It should be noted that the approximation within the fragments of a domain that have regular physical-geometric parameters along one of the directions is expedient to be carried out on the basis of the discrete-continual finite element method (DCFEM, and for the approximation of all other fragments it is necessary to use the standard finite element method (FEM. In the present publication, the formulas for the computing of displacements partial derivatives of displacements, strains and stresses within the finite element model (both within the finite element and the corresponding nodal values (with the use of averaging are presented. Boundary conditions between subdomains (respectively, discrete models and discrete-continual models and typical conditions such as “hinged support”, “free edge”, “perfect contact” (twelve basic (basic variants are available are under consideration as well. Governing formulas for computing of elements of the corresponding matrices of coefficients and vectors of the right-hand sides are given for each variant. All formulas are fully adapted for algorithmic implementation.
Ezoe, Masako; Sasaki, Miho; Hokura, Akiko; Nakai, Izumi; Terada, Yasuko; Yoshinaga, Tatsuki; Tukamoto, Katsumi; Hagiwara, Atsushi
2002-01-01
Two-dimensional imaging and a quantitative analysis of trace elements in rotifer, Brachionus plicatilis, belonging to zooplankton, were carried out by a synchrotron radiation X-ray fluorescence analysis (SR-XRF). The XRF imaging revealed that female rotifers accumulated Fe and Zn in the digestive organ and Fe, Zn, Cu, and Ca in the sexual organs, while the Mn level was high in the head. From a quantitative analysis by inductively coupled plasma mass spectrometry (ICP-MS), we found that rotifers eat the chlorella and accumulate the above elements in the body. The result of quantitative analyses of Mn, Cu, and Zn by SR-XRF in a single sample is in fair agreement with the average values determined by ICP-MS analyses, which were obtained by measuring a large number of rotifers, digested by nitric acid. The present study has demonstrated that SR-XRF is an effective tool for the trace element analysis of a single individual of rotifer. (author)
Ezoe, Masako; Sasaki, Miho; Hokura, Akiko; Nakai, Izumi [Tokyo Univ. of Science, Faculty of Science, Tokyo (Japan); Terada, Yasuko [Japan Synchrotron Radiation Research Inst., Mikazuki, Hyogo (Japan); Yoshinaga, Tatsuki; Tukamoto, Katsumi [Tokyo Univ., Ocean Research Inst., Tokyo (Japan); Hagiwara, Atsushi [Nagasaki Univ., Graduate School of Science and Technology, Bunkyou, Nagasaki (Japan)
2002-10-01
Two-dimensional imaging and a quantitative analysis of trace elements in rotifer, Brachionus plicatilis, belonging to zooplankton, were carried out by a synchrotron radiation X-ray fluorescence analysis (SR-XRF). The XRF imaging revealed that female rotifers accumulated Fe and Zn in the digestive organ and Fe, Zn, Cu, and Ca in the sexual organs, while the Mn level was high in the head. From a quantitative analysis by inductively coupled plasma mass spectrometry (ICP-MS), we found that rotifers eat the chlorella and accumulate the above elements in the body. The result of quantitative analyses of Mn, Cu, and Zn by SR-XRF in a single sample is in fair agreement with the average values determined by ICP-MS analyses, which were obtained by measuring a large number of rotifers, digested by nitric acid. The present study has demonstrated that SR-XRF is an effective tool for the trace element analysis of a single individual of rotifer. (author)
Nikhita Pekhale
2016-01-01
Full Text Available Introduction: The aim of this study is to evaluate stress and displacement effects of maxillary posterior intrusion mechanics with mini-implant anchorage by using finite element method. Materials and Methods: A computer stimulation of three-dimensional model maxilla with all teeth, PDL, bone, mini-implants, brackets, arch wire, force element, and transpalatal arch was constructed on the basis of average anatomic morphology. Finite element analysis was done to evaluate the amount of stress and its distribution during orthodontic intrusive force. Results: Increased Von Mises stress values were observed in mesio-cervical region of first molar. The middle third of second premolar and second molar and regions adjacent to force application sites also showed relatively high stress values. Minimum stress values were observed in apical region of first premolar as it is away from force application. Conclusion: Using three mini-implant and transpalatal arches, this study demonstrates that significant amount of true intrusion of maxillary molars could be obtained with lesser concentration of stresses in the apical area recorded.
Peter Schuller-Götzburg
2018-01-01
Full Text Available Purpose: the aim of the computational 3D-finite element study is to evaluate the influence of an augmented sinus lift with additional inserted bone grafting. The bone graft block stabilizes the implant in conjunction with conventional bone augmentation. Two finite element models were applied: the real geometry based bone models and the simplified geometry models. The bone graft block was placed in three different positions. The implants were loaded first with an axial force and then with forces simulating laterotrusion and protrusion. This study examines whether the calculated stress behavior is symmetrical for both models. Having established a symmetry between the primary axis, the laterotrusion and protrusion behavior reduces calculation efforts, by simplifying the model. Material and Methods: a simplified U-shaped 3D finite element model of the molar region of the upper jaw and a more complex anatomical model of the left maxilla with less cortical bone were created. The bone graft block was placed in the maxillary sinus. Then the von Mises stress distribution was calculated and analyzed at three block positions: at contact with the sinus floor, in the middle of the implant helix and in the upper third of the implant. The two finite element models were then compared to simplify the modelling. Results: the position of the bone graft block significantly influences the magnitude of stress distribution. A bone graft block positioned in the upper third or middle of the implant reduces the quantity of stress compared to the reference model without a bone graft block. The low bone graft block position is clearly associated with lower stress distribution in compact bone. We registered no significant differences in stress in compact bone with regard to laterotrusion or protrusion. Conclusions: maximum values of von Mises stresses in compact bone can be reduced significantly by using a bone graft block. The reduction of stress is nearly the same for
Dresvyannikov, A. F.; Kolpakov, M. E.
2018-05-01
X-ray fluorescence, X-ray phase analysis, and transmission Mössbauer and NGR spectrometry are used to study the formation, phase, and elemental composition of Fe-Ti particles. The interaction between Fe(III) ions and dispersed titanium in an aqueous solution containing chloride ions and HF is studied. It is shown that the resulting Fe-Ti samples are a set of core-shell microparticles with titanium cores coated with micro- and nanosized α-Fe nucleation centers with the thinness outer layer of iron(III) oxide characterized by a developed surface.
Bass, B.R.; Bryson, J.W.
1983-02-01
Certain studies of fracture phenomena, such as pressurized-thermal-shock of cracked structures, require that crack tip parameters be determined for combined thermal and mechanical loads. A method is proposed here that modifies the isothermal formulation of deLorenzi to account for thermal strains in cracked bodies. The formulation has been implemented in the virtual-crack-extension program ORVIRT (Oak Ridge VIRTual-Crack-Extension). Program ORVIRT performs energy release rate calculations for both 2- and 3-dimensional nonlinear models of crack configurations in engineering structures. Two applications of the ORVIRT program are described. In the first, semielliptical surface cracks in an experimental test vessel are analyzed under elastic-plastic conditions using the finite element method. The second application is a thick-walled test vessel subjected to combined pressure and thermal shock loading
Erdogan, E.
2007-01-01
In earth investigation done by using the direct current resistivity technique, impact of the change in the examined surface topography on determining the resistivity distrubition in the earth has been a frequently faced question. In order to get more fruitful results and make more correct interpretetions in earth surveying carried on the areas where topographical changes occur, modelling should be done by taking the change in surface topography into account and topography effect should be included into inversion. In this study impact of topography to the direct current resistivity method has been analysed. For this purpose, 2-D forward modeling algorithm has been developed by using finite element method. In this algorithm impact of topography can be incorporate into the model. Also the pseudo sections which is produced from the program can be imaged with topography. By using this algorithm response of models under different surface topography has been analysed and compared with the straight topography of same models
Degirmenci, Elif; Landais, Pascal
2013-10-20
Photonic band gap and transmission characteristics of 2D metallic photonic crystals at THz frequencies have been investigated using finite element method (FEM). Photonic crystals composed of metallic rods in air, in square and triangular lattice arrangements, are considered for transverse electric and transverse magnetic polarizations. The modes and band gap characteristics of metallic photonic crystal structure are investigated by solving the eigenvalue problem over a unit cell of the lattice using periodic boundary conditions. A photonic band gap diagram of dielectric photonic crystal in square lattice array is also considered and compared with well-known plane wave expansion results verifying our FEM approach. The photonic band gap designs for both dielectric and metallic photonic crystals are consistent with previous studies obtained by different methods. Perfect match is obtained between photonic band gap diagrams and transmission spectra of corresponding lattice structure.
Barall, Michael
2009-01-01
We present a new finite-element technique for calculating dynamic 3-D spontaneous rupture on an earthquake fault, which can reduce the required computational resources by a factor of six or more, without loss of accuracy. The grid-doubling technique employs small cells in a thin layer surrounding the fault. The remainder of the modelling volume is filled with larger cells, typically two or four times as large as the small cells. In the resulting non-conforming mesh, an interpolation method is used to join the thin layer of smaller cells to the volume of larger cells. Grid-doubling is effective because spontaneous rupture calculations typically require higher spatial resolution on and near the fault than elsewhere in the model volume. The technique can be applied to non-planar faults by morphing, or smoothly distorting, the entire mesh to produce the desired 3-D fault geometry. Using our FaultMod finite-element software, we have tested grid-doubling with both slip-weakening and rate-and-state friction laws, by running the SCEC/USGS 3-D dynamic rupture benchmark problems. We have also applied it to a model of the Hayward fault, Northern California, which uses realistic fault geometry and rock properties. FaultMod implements fault slip using common nodes, which represent motion common to both sides of the fault, and differential nodes, which represent motion of one side of the fault relative to the other side. We describe how to modify the traction-at-split-nodes method to work with common and differential nodes, using an implicit time stepping algorithm.
Fehm, Thomas Felix; Razansky, Daniel, E-mail: dr@tum.de [Institute for Biological and Medical Imaging (IBMI), Helmholtz Zentrum München, Neuherberg (Germany); Faculty of Medicine, Technische Universität München, Munich (Germany); Deán-Ben, Xosé Luís [Institute for Biological and Medical Imaging (IBMI), Helmholtz Zentrum München, Neuherberg (Germany)
2014-10-27
Ultrasonography and optoacoustic imaging share powerful advantages related to the natural aptitude for real-time image rendering with high resolution, the hand-held operation, and lack of ionizing radiation. The two methods also possess very different yet highly complementary advantages of the mechanical and optical contrast in living tissues. Nonetheless, efficient integration of these modalities remains challenging owing to the fundamental differences in the underlying physical contrast, optimal signal acquisition, and image reconstruction approaches. We report on a method for hybrid acquisition and reconstruction of three-dimensional pulse-echo ultrasound and optoacoustic images in real time based on passive ultrasound generation with an optical absorber, thus avoiding the hardware complexity of active ultrasound generation. In this way, complete hybrid datasets are generated with a single laser interrogation pulse, resulting in simultaneous rendering of ultrasound and optoacoustic images at an unprecedented rate of 10 volumetric frames per second. Performance is subsequently showcased in phantom experiments and in-vivo measurements from a healthy human volunteer, confirming general clinical applicability of the method.
Fehm, Thomas Felix; Deán-Ben, Xosé Luís; Razansky, Daniel
2014-10-01
Ultrasonography and optoacoustic imaging share powerful advantages related to the natural aptitude for real-time image rendering with high resolution, the hand-held operation, and lack of ionizing radiation. The two methods also possess very different yet highly complementary advantages of the mechanical and optical contrast in living tissues. Nonetheless, efficient integration of these modalities remains challenging owing to the fundamental differences in the underlying physical contrast, optimal signal acquisition, and image reconstruction approaches. We report on a method for hybrid acquisition and reconstruction of three-dimensional pulse-echo ultrasound and optoacoustic images in real time based on passive ultrasound generation with an optical absorber, thus avoiding the hardware complexity of active ultrasound generation. In this way, complete hybrid datasets are generated with a single laser interrogation pulse, resulting in simultaneous rendering of ultrasound and optoacoustic images at an unprecedented rate of 10 volumetric frames per second. Performance is subsequently showcased in phantom experiments and in-vivo measurements from a healthy human volunteer, confirming general clinical applicability of the method.
Fehm, Thomas Felix; Razansky, Daniel; Deán-Ben, Xosé Luís
2014-01-01
Ultrasonography and optoacoustic imaging share powerful advantages related to the natural aptitude for real-time image rendering with high resolution, the hand-held operation, and lack of ionizing radiation. The two methods also possess very different yet highly complementary advantages of the mechanical and optical contrast in living tissues. Nonetheless, efficient integration of these modalities remains challenging owing to the fundamental differences in the underlying physical contrast, optimal signal acquisition, and image reconstruction approaches. We report on a method for hybrid acquisition and reconstruction of three-dimensional pulse-echo ultrasound and optoacoustic images in real time based on passive ultrasound generation with an optical absorber, thus avoiding the hardware complexity of active ultrasound generation. In this way, complete hybrid datasets are generated with a single laser interrogation pulse, resulting in simultaneous rendering of ultrasound and optoacoustic images at an unprecedented rate of 10 volumetric frames per second. Performance is subsequently showcased in phantom experiments and in-vivo measurements from a healthy human volunteer, confirming general clinical applicability of the method.
Besuner, P.M.; Caughey, W.R.
1976-11-01
The finite element (FE) and influence function (IF) methods are compared for a three-dimensional elastic analysis of postulated circular-shaped surface cracks in the feedwater nozzle of a typical boiling water reactor (BWR). These are two of the possible methods for determining stress intensity factors for nozzle corner cracks. The FE method is incorporated in a direct manner. The IF method is used to compute stress intensity factors only when the uncracked stress field (i.e., the stress in the uncracked solid at the locus of the crack to be eventually considered) has been computed previously. Both the IF and FE methods are described in detail and are applied to several test cases chosen for their similarity to the nozzle crack problem and for the availablility of an accurate published result obtained from some recognized third method of solution
Oomori, H; Imura, S; Gesso, H
1992-04-01
To develop stem design achieving primary fixation of stems and effective load transfer to the femur, we studied stress analysis of stems in cementless total hip arthroplasty by two-dimensional finite element method using boundary friction layer in stem-bone interface. The results of analyses of stem-bone interface stresses and von Mises stresses at the cortical bones indicated that ideal stem design features would be as follows: 1) Sufficient length, with the distal end extending beyond the isthmus region. 2) Maximum possible width, to contact the cortical bones in the isthmus region. 3) No collars but a lateral shoulder at the proximal portion. 4) A distal tip, to contact the cortical bones at the distal portion.
Ichihashi, K; Imura, S; Oomori, H; Gesso, H
1994-11-01
We compared the biomechanical characteristics of bipolar and unipolar hemiarthroplasty on the proximal migration of the outer head by determining the von Mises stress distribution and acetabular (outer head) displacement with clinical assessment of hemiarthroplasty in 75 patients. This analysis used the two-dimensional finite element method, which incorporated boundary friction layers on both the inner and outer bearings of the prosthesis. Acetabular reaming increased stress within the pelvic bone and migration of the outer head. A combination of the acetabular reaming and bone transplantation increased the stress within the pelvic bone and grafted bone, and caused outer head migration. These findings were supported by clinical results. Although the bipolar endoprosthesis was biomechanically superior to the unipolar endoprosthesis, migration of the outer head still occurred. The bipolar endoprosthesis appeared to be indicated in cases of a femoral neck fracture or of avascular necrosis in the femoral head, but its use in cases of osteoarthritis in the hip required caution.
Silver, A.H.; Lee, J.Y.
1983-01-01
Cellular convection was studied rigorously during the development of the Clinch River Breeder Reactor Plant (CRBRP) Program Pumps. This paper presents the development of a three-dimensional finite-element heat transfer model which accounts for the cellular convection phenomena. A buoyancy driven cellular convection flow pattern is introduced in the annulus region between the upper inner structure and the pump tank. Steady-state thermal data were obtained for several test conditions for argon gas pressures up to 93 psig (741 kPa) and sodium operating temperatures to 1000 0 F (811 0 K). Test temperature distributions on the pump tank and inner structure were correlated with numerical results and excellent agreement was obtained
Adamik, V.; Matejovic, P.
1989-01-01
The problems are discussed of nonstationary, nonlinear dynamics of the continuum. A survey is presented of calculation methods in the given area with emphasis on the area of impact problems. A description is presented of the explicit finite elements method and its application to two-dimensional Cartesian and cylindrical configurations. Using the method the explicit calculation code FINEDAN was written which was tested in a series of verification calculations for different configurations and different types of continuum. The main characteristics are presented of the code and of some, of its practical applications. Envisaged trends of the development of the code and its possible applications in the technology of nuclear reactors are given. (author). 9 figs., 4 tabs., 10 refs
Ngoma, Jeff; Philippe, Pierre; Bonelli, Stéphane; Radjaï, Farhang; Delenne, Jean-Yves
2018-05-01
We present here a numerical study dedicated to the fluidization of a submerged granular medium induced by a localized fluid injection. To this end, a two-dimensional (2D) model is used, coupling the lattice Boltzmann method (LBM) with the discrete element method (DEM) for a relevant description of fluid-grains interaction. An extensive investigation has been carried out to analyze the respective influences of the different parameters of our configuration, both geometrical (bed height, grain diameter, injection width) and physical (fluid viscosity, buoyancy). Compared to previous experimental works, the same qualitative features are recovered as regards the general phenomenology including transitory phase, stationary states, and hysteretic behavior. We also present quantitative findings about transient fluidization, for which several dimensionless quantities and scaling laws are proposed, and about the influence of the injection width, from localized to homogeneous fluidization. Finally, the impact of the present 2D geometry is discussed, by comparison to the real three-dimensional (3D) experiments, as well as the crucial role of the prevailing hydrodynamic regime within the expanding cavity, quantified through a cavity Reynolds number, that can presumably explain some substantial differences observed regarding upward expansion process of the fluidized zone when the fluid viscosity is changed.
Nakagawa, M.
1984-01-01
Computer program ARKAS has been developed for the purpose of predicting core distortions and mechanical behaviour in a cluster of subassemblies under steady state conditions in LMFBR cores. This report describes the analytical models and numerical procedures employed in the code together with some typical results of the analysis made on large LMFBR cores. ARKAS is programmed in the FORTRAN-IV language and is capable of treating up to 260 assemblies in a cluster with flexible boundary conditions including mirror and rotational symmetry. The nonlinearity of the problem due to contact and separation is solved by the step iterative procedure based on the Newton-Raphson method. In each step iterative procedure, the linear matrix equation must be reconstructed and then solved directly. To save computer time and memory, the substructure method is adopted in the step of reconstructing the linear matrix equation, and in the step of solving the linear matrix equation, the block successive over-relaxation method is adopted. The program ARKAS computes, at every time step, 3-dimensional displacements and rotations of the subassemblies in the core and the interduct forces including at the nozzle tips and nozzle bases with friction effects. The code also has an ability to deal with the refueling and shuffling of subassemblies and to calculate the values of withdrawal forces. For the qualitative validation of the code, sample calculations were performed on the several bundle arrays. In these calculations, contact and separation processes under the influences of friction forces, off-center loading, duct rotations and torsion, thermal expansion and irradiation induced swelling and creep were analyzed. These results are quite reasonable in the light of the expected behaviour. This work was performed under the sponsorship of Toshiba Corporation
Gomez, C. F.; Mireles, O. R.; Stewart, E.
2016-01-01
The Space Capable Cryogenic Thermal Engine (SCCTE) effort considers a nuclear thermal rocket design based around a Low-Enriched Uranium (LEU) design fission reactor. The reactor core is comprised of bundled hexagonal fuel elements that directly heat hydrogen for expansion in a thrust chamber and hexagonal tie-tubes that house zirconium hydride moderator mass for the purpose of thermalizing fast neutrons resulting from fission events. Created 3D steady state Hex fuel rod model with 1D flow channels. Hand Calculation were used to set up initial conditions for fluid flow. The Hex Fuel rod uses 1D flow paths to model the channels using empirical correlations for heat transfer in a pipe. Created a 2-D axisymmetric transient to steady state model using the CFD turbulent flow and Heat Transfer module in COMSOL. This model was developed to find and understand the hydrogen flow that might effect the thermal gradients axially and at the end of the tie tube where the flow turns and enters an annulus. The Hex fuel rod and Tie tube models were made based on requirements given to us by CSNR and the SCCTE team. The models helped simplify and understand the physics and assumptions. Using pipe correlations reduced the complexity of the 3-D fuel rod model and is numerically more stable and computationally more time-efficient compared to the CFD approach. The 2-D axisymmetric tie tube model can be used as a reference "Virtual test model" for comparing and improving 3-D Models.
Zarrati, Simindokht; Heidari, Fatemeh; Kashani, Jamal
2015-01-01
Objectives: This finite element method study aimed to compare the amount of stress on an isolated mandibular second premolar in two conventional reciprocal parallel interface designs of removable partial dentures (RPDs) and the same RPD abutment tooth (not isolated). Materials and Methods: A Kennedy Class 1, modification 1 RPD framework was simulated on a 3D model of mandible with three different designs: an isolated tooth with a mesial rest, an isolated tooth with mesial and distal rests and an abutment with a mesial rest (which was not isolated); 26 N occlusal forces were exerted bilaterally on the first molar sites. Stress on the abutment teeth was analyzed using Cosmos Works 2009 Software. Results: In all designs, the abutment tooth stress concentration was located in the buccal alveolar crest. In the first model, the von Mises stress distribution in the contact area of I-bar clasp and cervical portion of the tooth was 19 MPa and the maximum stress was 30 MPa. In the second model, the maximum von Mises stress distribution was 15 MPa in the cervical of the tooth. In the third model, the maximum von Mises stress was located in the cervical of the tooth and the distal proximal plate. Conclusion: We recommend using both mesial and distal rests on the distal abutment teeth of distal extension RPDs. The abutment of an extension base RPD, which is not isolated in presence of its neighboring more anterior tooth, may have a better biomechanical prognosis. PMID:26884772
Maheshwari, B.K.; Truman, K.Z.; El Naggar, M.H.; Gould, P.L.
2004-01-01
The effects of material nonlinearity of soil and separation at the soil-pile interface on the dynamic behaviour of a single pile and pile groups are investigated. An advanced plasticity-based soil model, hierarchical single surface (HiSS), is incorporated in the finite element formulation. To simulate radiation effects, proper boundary conditions are used. The model and algorithm are verified with analytical results that are available for elastic and elastoplastic soil models. Analyses are performed for seismic excitation and for the load applied on the pile cap. For seismic analysis, both harmonic and transient excitations are considered. For loading on the pile cap, dynamic stiffness of the soil-pile system is derived and the effect of nonlinearity is investigated. The effects of spacing between piles are investigated, and it was found that the effect of soil nonlinearity on the seismic response is very much dependent on the frequency of excitation. For the loading on a pile cap, the nonlinearity increases the response for most of the frequencies of excitation while decreasing the dynamic stiffness of the soil-pile system. (author)
Tribst, João Paulo Mendes; de Morais, Dayana Campanelli; Alonso, Alexandre Abhdala; Piva, Amanda Maria de Oliveira Dal; Borges, Alexandre Luis Souto
2017-01-01
The increase of requests for implant-supported prosthesis (ISP) with zirconia as infrastructure has attracted a lot of attention due to its esthetics, biocompatibility, and survival rate similar to metallic infrastructure. The aim of this study was to evaluate the influence of two different framework materials on stress distribution over a bone tissue-simulating material. Two ISP were modeled and divided into two infrastructure materials: titanium (Ti) and zirconia. Then, these bars were attached to a modeled jaw with polyurethane properties to simulate bone tissue. An axial load of 200 N was applied on a standardized area for both systems. Maximum principal stress (MPS) on solids and microstrain (MS) generated through the jaw were analyzed by finite element analysis. According to MS, both models showed strains on peri-implant region of the penultimate (same side of the load application) and central implants. For MPS, more stress concentration was slightly higher in the left posterior region for Ti's bar. In prosthetic fixation screws, the MPS prevailed strongly in Ti protocol, while for zirconia's bar, the cervical of the penultimate implant was the one that highlighted larger areas of possible damages. The stress generated in all constituents of the system was not significantly influenced by the framework's material. This allows suggesting that in cases without components, the use of a framework in zirconia has biomechanical behavior similar to that of a Ti bar.
Zarrati, Simindokht; Bahrami, Mehran; Heidari, Fatemeh; Kashani, Jamal
2015-06-01
This finite element method study aimed to compare the amount of stress on an isolated mandibular second premolar in two conventional reciprocal parallel interface designs of removable partial dentures (RPDs) and the same RPD abutment tooth (not isolated). A Kennedy Class 1, modification 1 RPD framework was simulated on a 3D model of mandible with three different designs: an isolated tooth with a mesial rest, an isolated tooth with mesial and distal rests and an abutment with a mesial rest (which was not isolated); 26 N occlusal forces were exerted bilaterally on the first molar sites. Stress on the abutment teeth was analyzed using Cosmos Works 2009 Software. In all designs, the abutment tooth stress concentration was located in the buccal alveolar crest. In the first model, the von Mises stress distribution in the contact area of I-bar clasp and cervical portion of the tooth was 19 MPa and the maximum stress was 30 MPa. In the second model, the maximum von Mises stress distribution was 15 MPa in the cervical of the tooth. In the third model, the maximum von Mises stress was located in the cervical of the tooth and the distal proximal plate. We recommend using both mesial and distal rests on the distal abutment teeth of distal extension RPDs. The abutment of an extension base RPD, which is not isolated in presence of its neighboring more anterior tooth, may have a better biomechanical prognosis.
R. Daud
2013-06-01
Full Text Available Shielding interaction effects of two parallel edge cracks in finite thickness plates subjected to remote tension load is analyzed using a developed finite element analysis program. In the present study, the crack interaction limit is evaluated based on the fitness of service (FFS code, and focus is given to the weak crack interaction region as the crack interval exceeds the length of cracks (b > a. Crack interaction factors are evaluated based on stress intensity factors (SIFs for Mode I SIFs using a displacement extrapolation technique. Parametric studies involved a wide range of crack-to-width (0.05 ≤ a/W ≤ 0.5 and crack interval ratios (b/a > 1. For validation, crack interaction factors are compared with single edge crack SIFs as a state of zero interaction. Within the considered range of parameters, the proposed numerical evaluation used to predict the crack interaction factor reduces the error of existing analytical solution from 1.92% to 0.97% at higher a/W. In reference to FFS codes, the small discrepancy in the prediction of the crack interaction factor validates the reliability of the numerical model to predict crack interaction limits under shielding interaction effects. In conclusion, the numerical model gave a successful prediction in estimating the crack interaction limit, which can be used as a reference for the shielding orientation of other cracks.
Iman Zafarparandeh
2016-03-01
Full Text Available In some finite element analysis studies of models of sections of the spine, the three-dimensional solid model is built by assuming symmetry about the mid-sagittal plane of the section, whereas in other studies, the model is built from the exact geometry of the section. The influence of the method used to build the solid model on model parameters, in the case of the cervical spine, has not been reported in the literature. This issue is the subject of this study, with the section being C2–C7, the applied loadings being extension, flexion, left lateral bending, and right axial rotation (each of magnitude 1 Nm, and the model parameters determined being rotation, intradiskal pressure, and facet load at each of the segments. When all the parameter results were considered, it was found that, by and large, the influence of solid model construction method used (exact geometry vs assumption of symmetry about the mid-sagittal plane of the section was marginal. As construction of a symmetric finite element model requires less time and effort, construction of an asymmetric model may be justified in special cases only.
Olmez, Sultan; Dogan, Servet; Pekedis, Mahmut; Yildiz, Hasan
2014-09-01
To compare the pattern and amount of stress and displacement during maxillary sagittal distraction osteogenesis (DO) between a patient with unilateral cleft lip and palate (UCLP) and a noncleft patient. Three-dimensional finite element models for both skulls were constructed. Displacements of the surface landmarks and stress distributions in the circummaxillary sutures were analyzed after an anterior displacement of 6 mm was loaded to the elements where the inferior plates of the distractor were assumed to be fixed and were below the Le Fort I osteotomy line. In sagittal plane, more forward movement was found on the noncleft side in the UCLP model (-6.401 mm on cleft side and -6.651 mm on noncleft side for the central incisor region). However, similar amounts of forward movement were seen in the control model. In the vertical plane, a clockwise rotation occurred in the UCLP model, whereas a counterclockwise rotation was seen in the control model. The mathematical UCLP model also showed higher stress values on the sutura nasomaxillaris, frontonasalis, and zygomatiomaxillaris on the cleft side than on the normal side. Not only did the sagittal distraction forces produce advancement forces at the intermaxillary sutures, but more stress was also present on the sutura nasomaxillaris, sutura frontonasalis, and sutura zygomaticomaxillaris on the cleft side than on the noncleft side.
Fujihara, Hirohiko; Ueda, Masahiro
1975-01-01
In the design of chemical reactors or nuclear pressure vessels it is often important to evaluate the stress distribution in nozzle-to-shell intersections. The finite element method is a powerful tool for stress analysis, but it has a defects to require troublesome work in preparing input data. Specially, the mesh data of oblique nozzles and tangential nozzles, in which stress concentration is very high, are very difficult to be prepared. The authors made a mesh generation program which can be used to any nozzle-to-shell intersections, and combining this program with a three dimensional stress analysis program by the finite element method they made the stress analysis of nozzle-to-shell intersections under internal pressure. Consequently, stresses, strains and deformations of nozzles nonsymmetrical to spherical shells and nozzles tangential to cylindrical shells were made clear and it was shown that the curvature of the inner surface of the nozzle corner was a controlling factor in reducing stress concentration. (auth.)
Yan, Xu; Zhang, Xinwen; Chi, Weichao; Ai, Hongjun; Wu, Lin
2015-05-01
This study aimed to compare the influence of alveolar ridge cortical bone and sinus floor cortical bone in sinus areabi-cortical dental implantation by means of 3D finite element analysis. Three-dimensional finite element (FE) models in a posterior maxillary region with sinus membrane and the same height of alveolar ridge of 10 mm were generated according to the anatomical data of the sinus area. They were either with fixed thickness of crestal cortical bone and variable thickness of sinus floor cortical bone or vice versa. Ten models were assumed to be under immediate loading or conventional loading. The standard implant model based on the Nobel Biocare implant system was created via computer-aided design software. All materials were assumed to be isotropic and linearly elastic. An inclined force of 129 N was applied. Von Mises stress mainly concentrated on the surface of crestal cortical bone around the implant neck. For all the models, both the axial and buccolingual resonance frequencies of conventional loading were higher than those of immediate loading; however, the difference is less than 5%. The results showed that bi-cortical implant in sinus area increased the stability of the implant, especially for immediately loading implantation. The thickness of both crestal cortical bone and sinus floor cortical bone influenced implant micromotion and stress distribution; however, crestal cortical bone may be more important than sinus floor cortical bone.
Simindokht Zarrati
2015-11-01
Full Text Available Objectives: This finite element method study aimed to compare the amount of stress on an isolated mandibular second premolar in two conventional reciprocal parallel interface designs of removable partial dentures (RPDs and the same RPD abutment tooth (not isolated.Materials and Methods: A Kennedy Class 1, modification 1 RPD framework was simulated on a 3D model of mandible with three different designs: an isolated tooth with a mesial rest, an isolated tooth with mesial and distal rests and an abutment with a mesial rest (which was not isolated; 26 N occlusal forces were exerted bilaterally on the first molar sites. Stress on the abutment teeth was analyzed using Cosmos Works 2009 Software.Results: In all designs, the abutment tooth stress concentration was located in the buccal alveolar crest. In the first model, the von Mises stress distribution in the contact area of I-bar clasp and cervical portion of the tooth was 19 MPa and the maximum stress was 30 MPa. In the second model, the maximum von Mises stress distribution was 15 MPa in the cervical of the tooth. In the third model, the maximum von Mises stress was located in the cervical of the tooth and the distal proximal plate.Conclusion: We recommend using both mesial and distal rests on the distal abutment teeth of distal extension RPDs. The abutment of an extension base RPD, which is not isolated in presence of its neighboring more anterior tooth, may have a better biomechanical prognosis.
Yazdani-Asrami, Mohammad; Mirzaie, Mohammad; Shayegani Akmal, Amir Abbas
2013-01-01
Transformers are basically designed to operate under nominal voltage, rated frequency and also, pure sinusoidal load current. In recent decade, change in the type of loads and increasing use of power electronic devices with their nonsinusoidal current waveform has distorted the system voltage waveform as well. The losses of transformers include load and no-load losses. No-load loss continuously led to loss of energy in transformers that are connected to the network in all 24 h. With respect to high significance of energy and undesirable impacts of losses on the aging of transformers, the no-load loss is considered as a critical factor. Nowadays, it is necessary to apply a suitable method for calculation of no-load loss in presence of the voltage harmonics and over-excite conditions, especially for distribution transformers, as a result of harmonic increase in the voltage and current in the network and particular applications. In this paper, Finite Element Method (FEM) has been used to simulate nonsinusoidal voltage effects on no-load loss of transformers. Such simulation enables the software to simulate and analyze different electromagnetic parameters such as flux lines, flux density, losses, and etc under different input sources and with high accuracy. In addition, effect of nonsinusoidal voltages on no-load loss has been investigated by a typical experimental transformer using several practical tests. - Highlights: ► FEM has been employed to loss calculation of distribution transformer under distorted voltages. ► This method gives accurate results in comparison with standard or circuit based methods. ► A new version of 3D FEM has been used, this approach is electromagnetic based. ► In literature, FEM always used for study of transformer load loss and most of them based on magneto-static FEM. ► FEM results are validated by experiment for small test transformer
Fatalla, Abdalbseet A; Song, Ke; Du, Tianfeng; Cao, Yingguang
2012-12-01
The aim of this study was to establish the optimum design and attachment combination to support an overdenture with minimal stress and flexing produced in the alveolar bone surrounding any natural teeth and/or mini dental implants. Twelve models were included in the study: the six main models (A, B, C, D, E, and F) were categorized according to the support designs of the overdenture prosthesis, and each model was further subdivided according to the attachment combinations into model 1: with Dalbo elliptic and/or O-ring attachments only and model 2: with flexible acrylic attachments. Vertical loads (35 N) and 17.5 N lateral loads under static conditions were applied to the models to simulate the occlusal forces following the concept of lingualized occlusion. All conditions were created using a finite element software program. Maximum von Mises stress at the level of the attachments and at the bone support foundation interfaces were compared in all 12 models. The flexing of the mandible and the attachments were also compared qualitatively. Stress on these models was analyzed after the given loading condition. The results showed that the model with three freestanding mini dental implants and flexible acrylic attachments showed the lowest von Mises stress and flexing, while the models with four freestanding mini dental implants and O-ring attachments showed the highest von Mises stress. Three freestanding mini dental implants with flexible acrylic attachment systems supporting an overdenture were better choices than four mini dental implants with O-ring attachment systems, which showed the maximum flexing and stress values in this qualitative comparison. © 2012 by the American College of Prosthodontists.
Usami, Akinobu; Hara, Toshihiro; Ide, Yoshinobu
2003-01-01
The purpose of this study was to analyze the morphological and mechanical properties of the internal structures of maxillae at the molar region using a micro-CT system. Ten dentulous and edentulous maxillae were employed in this study. Images and angle information from all materials were taken by a micro-CT and 100 x 100 x 100 voxels were extracted from the fixed buccal and palatal molar regions in each material for three-dimensional morphological analysis of the internal structure. The bone volume fraction, trabecular thickness, trabecular separation and trabecular number were calculated. To analyze mechanical properties all voxels were converted to micro finite element models with element size of 33 x 33 x 33 μm 3 and maximal stiffness, axial stiffness and angle between the stiffest direction of trabecular and the axial loading direction (angleα) were determined using micro finite element method. In the result, the morphological changes including decrease of bone volume fraction, trabecular thickness and increase of trabecular separation were evident with tooth loss, although trabecular number was not changed. Mechanically, maximal stiffness was decreased with tooth loss at buccal region. However, the axial stiffness at buccal region was larger and the angleα was distributed widely in each edentulous maxilla, comparing to the same region of dentulous maxilla. These findings suggest that trabecular bone become thinner in both buccal and palatal regions, consequently maximal stiffness at buccal region become smaller with tooth loss. On the other hand, axial stiffness at the buccal region in edentulous was larger than one in dentulous. It seems to be caused by the change of the angleα. (author)
Limbert, Georges; van Lierde, Carl; Muraru, O Luiza; Walboomers, X Frank; Frank, Milan; Hansson, Stig; Middleton, John; Jaecques, Siegfried
2010-05-07
The first objective of this computational study was to assess the strain magnitude and distribution within the three-dimensional (3D) trabecular bone structure around an osseointegrated dental implant loaded axially. The second objective was to investigate the relative micromotions between the implant and the surrounding bone. The work hypothesis adopted was that these virtual measurements would be a useful indicator of bone adaptation (resorption, homeostasis, formation). In order to reach these objectives, a microCT-based finite element model of an oral implant implanted into a Berkshire pig mandible was developed along with a robust software methodology. The finite element mesh of the 3D trabecular bone architecture was generated from the segmentation of microCT scans. The implant was meshed independently from its CAD file obtained from the manufacturer. The meshes of the implant and the bone sample were registered together in an integrated software environment. A series of non-linear contact finite element (FE) analyses considering an axial load applied to the top of the implant in combination with three sets of mechanical properties for the trabecular bone tissue was devised. Complex strain distribution patterns are reported and discussed. It was found that considering the Young's modulus of the trabecular bone tissue to be 5, 10 and 15GPa resulted in maximum peri-implant bone microstrains of about 3000, 2100 and 1400. These results indicate that, for the three sets of mechanical properties considered, the magnitude of maximum strain lies within an homeostatic range known to be sufficient to maintain/form bone. The corresponding micro-motions of the implant with respect to the bone microstructure were shown to be sufficiently low to prevent fibrous tissue formation and to favour long-term osseointegration. Copyright 2010 Elsevier Ltd. All rights reserved.
NONE
1991-04-01
Research, development and evaluation were performed with an objective of establishing the basic technology related to three-dimensional circuit elements that integrate functions at ultra-high density. For the basic technology of lamination, the SOI technology suitable for the three-dimensional circuit elements was developed, and it has become possible to manufacture high-quality multi-layered crystalline structure by means of annealing that uses laser and electron beam. In addition, a lateral epitaxial technology for solid phase was developed, and the base to be applied to the three-dimensional circuit elements was established. Furthermore, the technology to put thin film circuits together would be useful for high-density integration in the future. The three-dimensional circuit makes parallel processing in each segment possible, whereas a possibility was shown that the processing can be performed at much higher speed than before. Actually a prototype three-dimensional circuit equipped with functions for parallel processing and judgment processing was fabricated. The image pre-processing which has been impossible on the real time basis in the conventional two-dimensional integrated circuit was realized in a speed as fast as milli-second order. These achievements lead to a belief that the targets for the present research and development have been achieved. (NEDO)
Çelik Köycü, Berrak; İmirzalıoğlu, Pervin
2017-07-01
Daily consumption of food and drink creates rapid temperature changes in the oral cavity. Heat transfer and thermal stress caused by temperature changes in restored teeth may damage the hard and soft tissue components, resulting in restoration failure. This study evaluates the temperature distribution and related thermal stress on mandibular molar teeth restored via three indirect restorations using three-dimensional (3D) finite element analysis (FEA). A 3D finite element model was constructed of a mandibular first molar and included enamel, dentin, pulp, surrounding bone, and indirect class 2 restorations of type 2 dental gold alloy, ceramic, and composite resin. A transient thermal FEA was performed to investigate the temperature distribution and the resulting thermal stress after simulated temperature changes from 36°C to 4 or 60°C for a 2-second time period. The restoration models had similar temperature distributions at 2 seconds in both the thermal conditions. Compared with 60°C exposure, the 4°C condition resulted in thermal stress values of higher magnitudes. At 4ºC, the highest stress value observed was tensile stress (56 to 57 MPa), whereas at 60°C, the highest stress value observed was compressive stress (42 to 43 MPa). These stresses appeared at the cervical region of the lingual enamel. The thermal stress at the restoration surface and resin cement showed decreasing order of magnitude as follows: composite > gold > ceramic, in both thermal conditions. The properties of the restorative materials do not affect temperature distribution at 2 seconds in restored teeth. The pulpal temperature is below the threshold for vital pulp tissue (42ºC). Temperature changes generate maximum thermal stress at the cervical region of the enamel. With the highest thermal expansion coefficient, composite resin restorations exhibit higher stress patterns than ceramic and gold restorations. © 2015 by the American College of Prosthodontists.
Li, Yong-Jiang; Zhang, Li-Cheng; Zhang, Mei-Chao; Yang, Guo-Jing; Lin, Rui-Xin; Cai, Chun-Yuan; Zhong, Shi-Zhen
2014-04-01
To discuss the primary stability of the fixed interface between the cementless prosthesis and femur, and its influence on bone ingrowth and secondary stability under the roughened surface and press fit of different prostheses by finite element analysis. :A three-dimensional finite element module of total hip arthroplasty (THA) was developed with Mimics software. There was a collection of data when simulating hip arthroplasty. The frictional coefficient between the fixed interface was 0,0.15,0.40 and 1.00 representing the roughness of prosthesis surface. The press fit was 0, 0.01,0.05 and 0.10 mm according to the operation. The Vion Mises stress distribution and the contact pressure,friction stress and relative sliding displacement between the interface were analysed and compared when simulating the maneuver of climbing stairs. At a fixed press fit of 0.05 mm,the contact pressure between the interface was 230 , 231, 222 and 275 MN under four different frictional coefficient (0,0. 15,0.40 and 1.00) with little change; the relative sliding displacement was 0.529, 0.129, 0.107 and 0.087 mm with a consistent and obvious decline. As the fixed frictional coefficient was 0.40,the contact pressure between the interface were 56.0,67.7 ,60.4 and 49.6 MN under four different press fit (0, 0.01, 0.05 and 0.10 mm) with a reduction; the relative sliding displacement was 0.064,0.062,0.043 and 0.042 mm with an obvious decline, and there was a maximal friction stress when press fit of 0.01 mm. There is a dynamic process of the bone remodeling and bone integration between the interface after hip replacement, determining the long-term outcome. The interface clearance and the frictional coefficient are the key factors of the bone integration.
Liu, Jingyin; Pan, Shaoxia; Dong, Jing; Mo, Zhongjun; Fan, Yubo; Feng, Hailan
2013-03-01
The aim of this study was to evaluate strain distribution in peri-implant bone, stress in the abutments and denture stability of mandibular overdentures anchored by different numbers of implants under different loading conditions, through three-dimensional finite element analysis (3D FEA). Four 3D finite element models of mandibular overdentures were established, using between one and four Straumann implants with Locator attachments. Three types of load were applied to the overdenture in each model: 100N vertical and inclined loads on the left first molar and a 100N vertical load on the lower incisors. The biomechanical behaviours of peri-implant bone, implants, abutments and overdentures were recorded. Under vertical load on the lower incisors, the single-implant overdenture rotated over the implant from side to side, and no obvious increase of strain was found in peri-implant bone. Under the same loading conditions, the two-implant-retained overdenture showed more apparent rotation around the fulcrum line passing through the two implants, and the maximum equivalent stress in the abutments was higher than in the other models. In the three-implant-supported overdenture, no strain concentration was found in cortical bone around the middle implant under three loading conditions. Single-implant-retained mandibular overdentures do not show damaging strain concentration in the bone around the only implant and may be a cost-effective treatment option for edentulous patients. A third implant can be placed between the original two when patients rehabilitated by two-implant overdentures report constant and obvious denture rotation around the fulcrum line. Copyright © 2012 Elsevier Ltd. All rights reserved.
Besuner, P.M.; Caughey, W.R.
1976-11-01
The paper compares the finite element (FE) and influence function (IF) methods for a three-dimensional elastic analysis of postulated circular-shaped surface cracks in the feedwater nozzle of a typical boiling water reactor (BWR). The FE method is incorporated in a direct manner. The nozzle and crack geometry and the complex loading are all included in the model which simulates the structural crack problem. The IF method is used to compute stress intensity factors only when the uncracked stress field (that is, the stress in the uncracked solid at the locus of the crack to be eventually considered) has been computed previously. The IF method evaluates correctly the disturbance of this uncracked stress field caused by the crack by utilizing a method of elastic superposition. Both the IF and FE methods are described in detail in the paper and are applied to several test cases chosen for their similarity to the nozzle crack problem and for the availability of an accurate published result obtained from some recognized third method of solution. Results are given which summarize both the accuracy and the direct computer costs of the two methods
Kang, Ju-Man; Park, Jae Hyun; Bayome, Mohamed; Oh, Moonbee; Park, Chong Ook; Mo, Sung-Seo
2016-01-01
Objective This study aimed to (1) evaluate the effects of maxillary second and third molar eruption status on the distalization of first molars with a modified palatal anchorage plate (MPAP), and (2) compare the results to the outcomes of the use of a pendulum and that of a headgear using three-dimensional finite element analysis. Methods Three eruption stages were established: an erupting second molar at the cervical one-third of the first molar root (Stage 1), a fully erupted second molar (Stage 2), and an erupting third molar at the cervical one-third of the second molar root (Stage 3). Retraction forces were applied via three anchorage appliance models: an MPAP with bracket and archwire, a bone-anchored pendulum appliance, and cervical-pull headgear. Results An MPAP showed greater root movement of the first molar than crown movement, and this was more noticeable in Stages 2 and 3. With the other devices, the first molar showed distal tipping. Transversely, the first molar had mesial-out rotation with headgear and mesial-in rotation with the other devices. Vertically, the first molar was intruded with an MPAP, and extruded with the other appliances. Conclusions The second molar eruption stage had an effect on molar distalization, but the third molar follicle had no effect. The application of an MPAP may be an effective treatment option for maxillary molar distalization. PMID:27668192
Mathew, Anoop; Nagachandran, K S; Vijayalakshmi, Devaki
2016-12-01
In this finite element (FE) study, the stress distribution and displacement pattern was evaluated in the mid-palatal area and around circum-maxillary sutures exerted by bone-borne palatal expander (BBPE) in comparison with conventional HYRAX rapid palatal expander in unilateral cleft lip and palate. Computed tomography scan images of a patient with unilateral cleft palate was used to create a FE model of the maxillary bone along with circum-maxillary sutures. A three-dimensional model of the conventional HYRAX (Hygienic Rapid Expander) expander and custom-made BBPE was created by laser scanning and programmed into the FE model. With the BBPE, the maximum stress was observed at the implant insertion site, whereas with the conventional HYRAX expander, it was at the dentition level. Among the circum-maxillary sutures, the zygomaticomaxillary suture experienced maximum stress followed by the zygomaticotemporal and nasomaxillary sutures. Displacement in the X-axis (transverse) was highest on the cleft side, and in the Y-axis (antero-posterior), it was highest in the posterior region in the BBPE. The total displacement was observed maximum in the mid-palatal cleft area in the BBPE, and it produced true skeletal expansion at the alveolar level without any dental tipping when compared with the conventional HYRAX expander.
Yu-chuan Yang
2016-01-01
Full Text Available The slope stability problem is an important issue for the safety of human beings and structures. The stability analysis of the three-dimensional (3D slope is essential to prevent landslides, but the most important and difficult problem is how to determine the 3D critical slip surface with the minimum factor of safety in earth slopes. Basing on the slope stress field with the finite element method, a stability analysis method is proposed to determine the critical slip surface and the corresponding safety factor of 3D soil slopes. Spherical and ellipsoidal slip surfaces are considered through the analysis. The moment equilibrium is used to compute the safety factor combined with the Mohr-Coulomb criteria and the limit equilibrium principle. Some assumptions are introduced to reduce the search range of center points and the radius of spheres or ellipsoids. The proposed method is validated by a classical 3D benchmark soil slope. Simulated results indicate that the safety factor of the benchmark slope is 2.14 using the spherical slip surface and 2.19 using the ellipsoidal slip surface, which is close to the results of previous methods. The simulated results indicate that the proposed method can be used for the stability analysis of a 3D soil slope.
Kanneganti, Krishna Chaitanya; Vinnakota, Dileep Nag; Pottem, Srinivas Rao; Pulagam, Mahesh
2018-01-01
The purpose of this study is to compare the effect of implant-abutment connections, abutment angulations, and screw lengths on screw loosening (SL) of preloaded abutment using three dimensional (3D) finite element analysis. 3D models of implants (conical connection with hex/trilobed connections), abutments (straight/angulated), abutment screws (short/long), and crown and bone were designed using software Parametric Technology Corporation Creo and assembled to form 8 simulations. After discretization, the contact stresses developed for 150 N vertical and 100 N oblique load applications were analyzed, using ABAQUS. By assessing damage initiation and shortest fatigue load on screw threads, the SL for 2.5, 5, and 10 lakh cyclic loads were estimated, using fe-safe program. The obtained values were compared for influence of connection design, abutment angulation, and screw length. In straight abutment models, conical connection showed more damage (14.3%-72.3%) when compared to trilobe (10.1%-65.73%) at 2.5, 5, and 10 lakh cycles for both vertical and oblique loads, whereas in angulated abutments, trilobe (16.1%-76.9%) demonstrated more damage compared to conical (13.5%-70%). Irrespective of the connection type and abutment angulation, short screws showed more percentage of damage compared to long screws. The present study suggests selecting appropriate implant-abutment connection based on the abutment angulation, as well as preferring long screws with more number of threads for effective preload retention by the screws.
Anoop Mathew
2016-11-01
Full Text Available Abstract Background In this finite element (FE study, the stress distribution and displacement pattern was evaluated in the mid-palatal area and around circum-maxillary sutures exerted by bone-borne palatal expander (BBPE in comparison with conventional HYRAX rapid palatal expander in unilateral cleft lip and palate. Methods Computed tomography scan images of a patient with unilateral cleft palate was used to create a FE model of the maxillary bone along with circum-maxillary sutures. A three-dimensional model of the conventional HYRAX (Hygienic Rapid Expander expander and custom-made BBPE was created by laser scanning and programmed into the FE model. Results With the BBPE, the maximum stress was observed at the implant insertion site, whereas with the conventional HYRAX expander, it was at the dentition level. Among the circum-maxillary sutures, the zygomaticomaxillary suture experienced maximum stress followed by the zygomaticotemporal and nasomaxillary sutures. Displacement in the X-axis (transverse was highest on the cleft side, and in the Y-axis (antero-posterior, it was highest in the posterior region in the BBPE. Conclusions The total displacement was observed maximum in the mid-palatal cleft area in the BBPE, and it produced true skeletal expansion at the alveolar level without any dental tipping when compared with the conventional HYRAX expander.
Tominaga, Jun-ya; Ozaki, Hiroya; Chiang, Pao-Chang; Sumi, Mayumi; Tanaka, Motohiro; Koga, Yoshiyuki; Bourauel, Christoph; Yoshida, Noriaki
2014-08-01
It has been found that controlled movement of the anterior teeth can be obtained by attaching a certain length of power arm onto an archwire in sliding mechanics. However, the impact of the archwire/bracket play on anterior tooth movement has not been clarified. The purpose of this study was to compare the effect of the power arm on anterior tooth movements with different dimensions of bracket slots and archwires. A 3-dimensional finite element method was used to simulate en-masse anterior tooth retraction in sliding mechanics. Displacements of the maxillary central incisor and the archwire deformation were calculated when applying retraction forces from different lengths of power arms. When a 0.017 × 0.022-in archwire was engaged into the 0.018-in slot bracket, bodily movement of the incisor was obtained with 9.1-mm length of the power arm. When a 0.022-in slot system was coupled with a 0.019 × 0.025-in archwire, bodily movement was observed with a power arm length of 11.6 mm. Archwire/bracket play has a remarkable impact on anterior tooth movement. An effective torque application to the anterior teeth becomes clinically difficult in sliding mechanics combined with power arms when the archwire/bracket play is large. Copyright © 2014 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.
Sobajima, M; Yamazaki, T; Yoshikawa, K; Ohnishi, M; Toku, H; Masuda, K; Kitagaki, J; Nakamura, T
1999-01-01
In January 1997, the Beijing FEL observed large laser amplification at 8-18 mu m. However, through the collaborative work, it was found from both experiments and numerical simulations that the laser loss on the beam tube wall was not negligible, and that the saturation was not seen in the relatively long wavelength range because of this loss. This calls for further investigation on the effects of the beam tube of finite size. In order to include such effects self-consistently, we have developed a new three-dimensional code that can solve equations with the boundary conditions of the beam tube by using the Finite Element Method. Results show that the beam tube effects are dominant in deriving higher laser modes in the tube, compared with the optical guiding effects, and consequently reduced gain especially in the longer wavelength range, where the beam tube effects are greatly emphasized. It is also found that TEM sub 0 sub 2 mode is the most dominant higher mode in the beam tube, and is also the main cause of...
Runde, Wolfgang; Bean, Amanda C; Brodnax, Lia F; Scott, Brian L
2006-03-20
Two americium(III) iodates, beta-Am(IO3)3 (I) and alpha-Am(IO3)3 (II), have been prepared from the aqueous reactions of Am(III) with KIO(4) at 180 degrees C and have been characterized by single-crystal X-ray diffraction, diffuse reflectance, and Raman spectroscopy. The alpha-form is consistent with the known structure type I of anhydrous lanthanide iodates. It consists of a three-dimensional network of pyramidal iodate groups bridging [AmO8] polyhedra where each of the americium ions are coordinated to eight iodate ligands. The beta-form reveals a novel architecture that is unknown within the f-element iodate series. beta-Am(IO3)3 exhibits a two-dimensional layered structure with nine-coordinate Am(III) atoms. Three crystallographically unique pyramidal iodate anions link the Am atoms into corrugated sheets that interact with one another through intermolecular IO3-...IO3- interactions forming dimeric I2O10 units. One of these anions utilizes all three O atoms to simultaneously bridge three Am atoms. The other two iodate ligands bridge only two Am atoms and have one terminal O atom. In contrast to alpha-Am(IO3)3, where the [IO3] ligands are solely corner-sharing with [AmO8] polyhedra, a complex arrangement of corner- and edge-sharing mu2- and mu3-[IO3] pyramids can be found in beta-Am(IO3)3. Crystallographic data: I, monoclinic, space group P2(1)/n, a = 8.871(3) A, b = 5.933(2) A, c = 15.315(4) A, beta = 96.948(4) degrees , V = 800.1(4) A(3), Z = 4; II, monoclinic, space group P2(1)/c, a = 7.243(2) A, b = 8.538(3) A, c = 13.513(5) A, beta = 100.123(6) degrees , V = 822.7(5) A(3), Z = 4.
Sandesh S Pai
2017-01-01
Full Text Available Aims: This study aims to analyze the effects of intrusive force, retraction force, and torque control on the maxillary central incisors with varying degrees of collum angle in labial and lingual orthodontic treatment procedures using finite element analysis. Subjects and Methods: Four pairs of three-dimensional finite element models (FEMs representative of maxillary central incisor with periodontal ligament (PDL and alveolar bone were constructed using ANSYS software (version 5.4, ANSYS Inc., Canonsburg, PA, USA. The models with 0°, 5°, 10°, and 15° were created based on crown root angulation. Four models for labial and four models for lingual orthodontic procedure were constructed. Each model was subjected to three forces, i.e., retraction force of 1 N, lingual root torque of −5 × 10−3 N and intrusive force of 0.64 N on crown with labially and lingually positioned brackets. Principal stress and strain, center of rotation and root apex displacement were monitored. Statistical Analysis Used: Not required (FEM study. Results: With the increase in collum angle, the stress-strain distribution in PDL was increased in both labial orthodontics (LaO and lingual orthodontics (LiO. Stress-strain distribution in the PDL with LiO was more in all the models as compared to LaO. There was more of tipping movement as collum angle increased from 0° to 15° in both LaO and LiO. The amount of intrusion reduced as the collum angle increased in both the systems. However, more of intrusion was seen in LaO. With increase in collum angle, the center of rotation moved cervically in both the systems. Conclusions: From the present study, we conclude that as the collum angle increased, the stress-strain distribution increased in LaO and LiO. The center of rotation shifted cervically, and the intrusion decreased when collum angle increased. The values were more marked in LiO.
Vincenzo De Novellis
2016-08-01
Full Text Available In this paper, we propose an advanced methodology to perform three-dimensional (3D Finite Element (FE modeling to investigate the kinematical evolution of a slow landslide phenomenon. Our approach benefits from the effective integration of the available geological, geotechnical and satellite datasets to perform an accurate simulation of the landslide process. More specifically, we fully exploit the capability of the advanced Differential Synthetic Aperture Radar Interferometry (DInSAR technique referred to as the Small BAseline Subset (SBAS approach to provide spatially dense surface displacement information. Subsequently, we analyze the physical behavior characterizing the observed landslide phenomenon by means of an inverse analysis based on an optimization procedure. We focus on the Ivancich landslide phenomenon, which affects a residential area outside the historical center of the town of Assisi (Central Italy. Thanks to the large amount of available information, we have selected this area as a representative case study highlighting the capability of advanced 3D FE modeling to perform effective risk analyses of slow landslide processes and accurate urban development planning. In particular, the FE modeling is constrained by using the data from 7 litho-stratigraphic cross-sections and 62 stratigraphic boreholes; and the optimization procedure is carried out using the SBAS-DInSAR retrieved results by processing 39 SAR images collected by the Cosmo-SkyMed (CSK constellation in the 2009–2012 time span. The achieved results allow us to explore the spatial and temporal evolution of the slow-moving phenomenon and via comparison with the geomorphological data, to derive a synoptic view of the kinematical activity of the urban area affected by the Ivancich landslide.
Ikman Ishak, Muhammad; Shafi, Aisyah Ahmad; Mohamad, Su Natasha; Jizat, Noorlindawaty Md
2018-03-01
The design of dental implant body has a major influence on the stress dissipation over adjacent bone as numbers of implant failure cases reported in past clinical studies. Besides, the inappropriate implant features may cause excessive high or low stresses which could possibly contribute to pathologic bone resorption or atrophy. The aim of this study is to evaluate the effect of different configurations of implant neck on stress dispersion within the adjacent bone via three-dimensional (3-D) finite element analysis (FEA). A set of computed tomography (CT) images of craniofacial was used to reconstruct a 3-D model of mandible using an image-processing software. The selected region of interest was the left side covering the second premolar, first molar and second molar regions. The bone model consisted of both compact (cortical) and porous (cancellous) structures. Three dental implant sets (crown, implant body, and abutment) with different designs of implant neck – straight, tapered with 15°, and tapered with 30° were modelled using a computer-aided design (CAD) software and all models were then analysed via 3-D FEA software. Top surface of first molar crown was subjected to occlusal forces of 114.6 N, 17.2 N, and 23.4 N in the axial, lingual, and mesio-distal directions, respectively. All planes of the mandible model were rigidly constrained in all directions. The result has demonstrated that the straight implant body neck is superior in attributing to high stress generation over adjacent bone as compared to others. This may associate with lower frictional resistance produced than those of tapered designs to withstand the applied loads.
Zaafarani, N.; Raabe, D.; Singh, R.N.; Roters, F.; Zaefferer, S.
2006-01-01
This paper reports a three-dimensional (3D) study of the microstructure and texture below a conical nanoindent in a (111) Cu single crystal at nanometer-scale resolution. The experiments are conducted using a joint high-resolution field emission scanning electron microscopy/electron backscatter diffraction (EBSD) set-up coupled with serial sectioning in a focused ion beam system in the form of a cross-beam 3D crystal orientation microscope (3D EBSD). The experiments (conducted in sets of subsequent (112-bar ) cross-section planes) reveal a pronounced deformation-induced 3D patterning of the lattice rotations below the indent. In the cross-section planes perpendicular to the (111) surface plane below the indenter tip the observed deformation-induced rotation pattern is characterized by an outer tangent zone with large absolute values of the rotations and an inner zone closer to the indenter axis with small rotations. The mapping of the rotation directions reveals multiple transition regimes with steep orientation gradients and frequent changes in sign. The experiments are compared to 3D elastic-viscoplastic crystal plasticity finite element simulations adopting the geometry and boundary conditions of the experiments. The simulations show a similar pattern for the absolute orientation changes but they fail to predict the fine details of the patterning of the rotation directions with the frequent changes in sign observed in the experiment. Also the simulations overemphasize the magnitude of the rotation field tangent to the indenter relative to that directly below the indenter tip
Yamanishi, Yasufumi; Yamaguchi, Satoshi; Imazato, Satoshi; Nakano, Tamaki; Yatani, Hirofumi
2014-09-01
Occlusal overloading causes peri-implant bone resorption. Previous studies examined stress distribution in alveolar bone around commercial implants using three-dimensional (3D) finite element analysis. However, the commercial implants contained some different designs. The purpose of this study is to reveal the effect of the target design on peri-implant bone stress and abutment micromovement. Six 3D implant models were created for different implant-abutment joints: 1) internal joint model (IM); 2) external joint model (EM); 3) straight abutment (SA) shape; 4) tapered abutment (TA) shapes; 5) platform switching (PS) in the IM; and 6) modified TA neck design (reverse conical neck [RN]). A static load of 100 N was applied to the basal ridge surface of the abutment at a 45-degree oblique angle to the long axis of the implant. Both stress distribution in peri-implant bone and abutment micromovement in the SA and TA models were analyzed. Compressive stress concentrated on labial cortical bone and tensile stress on the palatal side in the EM and on the labial side in the IM. There was no difference in maximum principal stress distribution for SA and TA models. Tensile stress concentration was not apparent on labial cortical bone in the PS model (versus IM). Maximum principal stress concentrated more on peri-implant bone in the RN than in the TA model. The TA model exhibited less abutment micromovement than the SA model. This study reveals the effects of the design of specific components on peri-implant bone stress and abutment displacement after implant-supported single restoration in the anterior maxilla.
Aradya, Anupama; Kumar, U Krishna; Chowdhary, Ramesh
2016-01-01
The study was designed to evaluate and compare stress distribution in transcortical section of bone with normal abutment and platform switched abutment under vertical and oblique forces in posterior mandible region. A three-dimensional finite element model was designed using ANSYS 13.0 software. The type of bone selection for the model was made of type II mandibular bone, having cortical bone thickness ranging from 0.595 mm to 1.515 mm with the crestal region measuring 1.5 mm surrounding dense trabecular bone. The implant will be modulated at 5 mm restorative platform and tapering down to 4.5 mm wide at the threads, 13 mm long with an abutment 3 mm in height. The models will be designed for two situations: (1) An implant with a 5 mm diameter abutment representing a standard platform in the posterior mandible region. (2) An implant with a 4.5 mm diameter abutment representing platform switching in the posterior mandible region. Force application was performed in both oblique and vertical conditions using 100 N as a representative masticatory force. For oblique loading, a force of 100 N was applied at 15° from the vertical axis. von Mises stress analysis was evaluated. The results of the study showed cortical stress in the conventional and platform switching model under oblique forces were 59.329 MPa and 39.952 MPa, respectively. Cortical stress in the conventional and platform switching model under vertical forces was 13.914 MPa and 12.793 MPa, respectively. Results from this study showed the platform switched abutment led to relative decrease in von Mises stress in transcortical section of bone compared to normal abutment under vertical and oblique forces in posterior mandible region.
Wu, Aaron Yu-Jen; Hsu, Jui-Ting; Chee, Winston; Lin, Yun-Te; Fuh, Lih-Jyh; Huang, Heng-Li
2016-09-01
Small-diameter dental implants are associated with a higher risk of implant failure. This study used both three-dimensional finite-element (FE) simulations and in-vitro experimental tests to analyze the stresses and strains in both the implant and the surrounding bone when using one-piece (NobelDirect) and two-piece (NobelReplace) small-diameter implants, with the aim of understanding the underlying biomechanical mechanisms. Six experimental artificial jawbone models and two FE models were prepared for one-piece and two-piece 3.5-mm diameter implants. Rosette strain gauges were used for in-vitro tests, with peak values of the principal bone strain recorded with a data acquisition system. Implant stability as quantified by Periotest values (PTV) were also recorded for both types of implants. Experimental data were analyzed statistically using Wilcoxon's rank-sum test. In FE simulations, the peak value and distribution of von-Mises stresses in the implant and bone were selected for evaluation. In in-vitro tests, the peak bone strain was 42% lower for two-piece implants than for one-piece implants. The PTV was slightly lower for one-piece implants (PTV = -6) than for two-piece implants (PTV = -5). In FE simulations, the stresses in the bone and implant were about 23% higher and 12% lower, respectively, for one-piece implants than those for two-piece implants. Due to the higher peri-implant bone stresses and strains, one-piece implants (NobelDirect) might be not suitable for use as small-diameter implants. Copyright © 2016. Published by Elsevier B.V.
Kermanshah, Hamid; Geramy, Allahyar; Ebrahimi, Shahram Farzin; Bitaraf, Tahereh
2012-12-01
This study evaluated von Mises stress distribution, flexural strength and interface micrographs of IPS-Empress II (IPS) inlay-retained fixed partial dentures (IRFPD) reinforced with Zirconia bars (Zb). In the Finite element analysis, six three-dimensional models of IRFPD were designed using Solid Works 2006. Five models were reinforced with different Zb and a model without Zb was considered as a control. The bridges were loaded by 200 and 500 N forces at the middle of the pontic on the occlusal surface. Subsequently, von Mises stress and displacement of the models were evaluated along a defined path. In the experimental part, 21 bar shape specimens were fabricated from lithium disilicate and zirconia ceramic in three different designs. The zirconia-IPS interfaces and the fractured surfaces of flexural test were observed using SEM. In the connector area, von Mises stress and displacement of the models with Zb under a load of 500 N were decreased compared to the model without the Zb; however, this difference was not considerable at a load of 200 N. In the mesial connector, Von Mises stress and displacement was decreased from 12.5 Mpa for the control model tested at 500 N to 7.0 Mpa for the model with Zb and from 0.0050-0.0041 mm, respectively. SEM analyses showed that, before fracture, interfacial gaps were not observed along the interfaces, but initiated cracks propagated along the interfaces after flexural loading. IPS IRFPD reinforced by Zb can tolerate higher stresses while still functioning effectively and the interfaces may have desirable adaption.
Alvarez-Arenal, Angel; Gonzalez-Gonzalez, Ignacio; deLlanos-Lanchares, Hector; Brizuela-Velasco, Aritza; Dds, Elena Martin-Fernandez; Ellacuria-Echebarria, Joseba
2017-12-01
The aim of this study was to evaluate and compare the bone stress around implants in mandibular 2-implant overdentures depending on the implant location and different loading conditions. Four 3-dimensional finite element models simulating a mandibular 2-implant overdenture and a Locator attachment system were designed. The implants were located at the lateral incisor, canine, second premolar, and crossed-implant levels. A 150 N unilateral and bilateral vertical load of different location was applied, as was 40 N when combined with midline load. Data for von Mises stress were produced numerically, color coded, and compared between the models for peri-implant bone and loading conditions. With unilateral loading, in all 4 models much higher peri-implant bone stress values were recorded on the load side compared with the no-load side, while with bilateral occlusal loading, the stress distribution was similar on both sides. In all models, the posterior unilateral load showed the highest stress, which decreased as the load was applied more mesially. In general, the best biomechanical environment in the peri-implant bone was found in the model with implants at premolar level. In the crossed-implant model, the load side greatly altered the biomechanical environment. Overall, the overdenture with implants at second premolar level should be the chosen design, regardless of where the load is applied. The occlusal loading application site influences the bone stress around the implant. Bilateral occlusal loading distributes the peri-implant bone stress symmetrically, while unilateral loading increases it greatly on the load side, no matter where the implants are located.
Jörn, Daniela; Kohorst, Philipp; Besdo, Silke; Borchers, Lothar; Stiesch, Meike
2016-01-01
Since bacterial leakage along the implant-abutment interface may be responsible for peri-implant infections, a realistic estimation of the interface gap width during function is important for risk assessment. The purpose of this study was to compare two methods for investigating microgap formation in a loaded dental implant, namely, microcomputed tomography (micro-CT) and three-dimensional (3D) nonlinear finite element analysis (FEA); additionally, stresses to be expected during loading were also evaluated by FEA. An implant-abutment complex was inspected for microgaps between the abutment and implant in a micro-CT scanner under an oblique load of 200 N. A numerical model of the situation was constructed; boundary conditions and external load were defined according to the experiment. The model was refined stepwise until its load-displacement behavior corresponded sufficiently to data from previous load experiments. FEA of the final, validated model was used to determine microgap widths. These were compared with the widths as measured in micro-CT inspection. Finally, stress distributions were evaluated in selected regions. No microgaps wider than 13 μm could be detected by micro-CT for the loaded implant. FEA revealed gap widths up to 10 μm between the implant and abutment at the side of load application. Furthermore, FEA predicted plastic deformation in a limited area at the implant collar. FEA proved to be an adequate method for studying microgap formation in dental implant-abutment complexes. FEA is not limited in gap width resolution as are radiologic techniques and can also provide insight into stress distributions within the loaded complex.
Schmid, J.
1985-11-01
A package of updated computer codes for velocity and temperature field calculations for a fast reactor fuel subassembly (or its part) by the finite element method is described. Isoparametric triangular elements of the second degree are used. (author)
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.
Biffle, J.H.; Blanford, M.L.
1994-05-01
JAC2D is a two-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 equations. The method is implemented in a two-dimensional setting with various methods for accelerating convergence. Sliding interface logic is also implemented. A four-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.
Villalva, Gustavo Jose
The search for life in other planets and solar systems by scientists and engineers brings about an effort to design and develop equipment of high standards which extend the capability to listen for signals which have been traveling in space many light years. In this study the purpose was to provide a more realistic and illustrative scientific understanding of one such piece of precision equipment, the dielectric resonator, which designers seek to extend its frequency stability below 10-15. At such tolerances special cryogenic cooling procedures are required. Due to its accuracy it can be used to set short term time and frequency standards to correct the atomic clock. A theoretical means of studying this type of resonant device is necessary. One contribution made in extending the current understanding of such a device is the scientific tool developed specifically for this dissertation. It applies the Minimum Theorem from variational calculus using edge finite elements for numerical modeling. The use of quasi-linear vector basis functions allowed an implementation of Helmholtz's three-dimensional equation without a penalty term. Furthermore, the intermixing of spurious solutions with the true ones due to a nodal basis was eliminated. Calculation of the average edge electric fields was made possible by applying the Rayleigh-Ritz criterion. Model enclosure was provided by a cylindrical metal shield situated in a rectangular coordinate system. Linear, homogeneous, nonmagnetic, lossless, uniaxial, and anisotropic media were considered. Integration of NASA's Unix Lanczos eigensolver permitted the accurate estimation of the smaller eigenvalues and associated vectors for large matrices on workstations and personal computers in relatively short computational times. Calculation of the lower frequency modes demonstrated the ability to address device imperfections for two selected cases. Both were influenced by problems encountered in the use of crystals constrained by cost, or
Quantum Distinction: Quantum Distinctiones!
Zeps, Dainis
2009-01-01
10 pages; How many distinctions, in Latin, quantum distinctiones. We suggest approach of anthropic principle based on anthropic reference system which should be applied equally both in theoretical physics and in mathematics. We come to principle that within reference system of life subject of mathematics (that of thinking) should be equated with subject of physics (that of nature). For this reason we enter notions of series of distinctions, quantum distinction, and argue that quantum distinct...
Group Frames With Few Distinct Inner Products and Low Coherence
Thill, Matthew
2015-10-01
Frame theory has been a popular subject in the design of structured signals and codes in recent years, with applications ranging from the design of measurement matrices in compressive sensing, to spherical codes for data compression and data transmission, to spacetime codes for MIMO communications, and to measurement operators in quantum sensing. High-performance codes usually arise from designing frames whose elements have mutually low coherence. Building off the original “group frame” design of Slepian which has since been elaborated in the works of Vale and Waldron, we present several new frame constructions based on cyclic and generalized dihedral groups. Slepian\\'s original construction was based on the premise that group structure allows one to reduce the number of distinct inner pairwise inner products in a frame with n elements from [(n(n-1))/2] to n-1. All of our constructions further utilize the group structure to produce tight frames with even fewer distinct inner product values between the frame elements. When n is prime, for example, we use cyclic groups to construct m-dimensional frame vectors with at most [(n-1)/m] distinct inner products. We use this behavior to bound the coherence of our frames via arguments based on the frame potential, and derive even tighter bounds from combinatorial and algebraic arguments using the group structure alone. In certain cases, we recover well-known Welch bound achieving frames. In cases where the Welch bound has not been achieved, and is not known to be achievable, we obtain frames with close to Welch bound performance.
Hellen, Christopher U T; de Breyne, Sylvain
2007-06-01
The 5' untranslated regions (UTRs) of the RNA genomes of Flaviviridae of the Hepacivirus and Pestivirus genera contain internal ribosomal entry sites (IRESs) that are unrelated to the two principal classes of IRESs of Picornaviridae. The mechanism of translation initiation on hepacivirus/pestivirus (HP) IRESs, which involves factor-independent binding to ribosomal 40S subunits, also differs fundamentally from initiation on these picornavirus IRESs. Ribosomal binding to HP IRESs requires conserved sequences that form a pseudoknot and the adjacent IIId and IIIe domains; analogous elements do not occur in the two principal groups of picornavirus IRESs. Here, comparative sequence analysis was used to identify a subset of picornaviruses from multiple genera that contain 5' UTR sequences with significant similarities to HP IRESs. They are avian encephalomyelitis virus, duck hepatitis virus 1, duck picornavirus, porcine teschovirus, porcine enterovirus 8, Seneca Valley virus, and simian picornavirus. Their 5' UTRs are predicted to form several structures, in some of which the peripheral elements differ from the corresponding HP IRES elements but in which the core pseudoknot, domain IIId, and domain IIIe elements are all closely related. These findings suggest that HP-like IRESs have been exchanged between unrelated virus families by recombination and support the hypothesis that RNA viruses consist of modular coding and noncoding elements that can exchange and evolve independently.
Hellen, Christopher U. T.; de Breyne, Sylvain
2007-01-01
The 5′ untranslated regions (UTRs) of the RNA genomes of Flaviviridae of the Hepacivirus and Pestivirus genera contain internal ribosomal entry sites (IRESs) that are unrelated to the two principal classes of IRESs of Picornaviridae. The mechanism of translation initiation on hepacivirus/pestivirus (HP) IRESs, which involves factor-independent binding to ribosomal 40S subunits, also differs fundamentally from initiation on these picornavirus IRESs. Ribosomal binding to HP IRESs requires conserved sequences that form a pseudoknot and the adjacent IIId and IIIe domains; analogous elements do not occur in the two principal groups of picornavirus IRESs. Here, comparative sequence analysis was used to identify a subset of picornaviruses from multiple genera that contain 5′ UTR sequences with significant similarities to HP IRESs. They are avian encephalomyelitis virus, duck hepatitis virus 1, duck picornavirus, porcine teschovirus, porcine enterovirus 8, Seneca Valley virus, and simian picornavirus. Their 5′ UTRs are predicted to form several structures, in some of which the peripheral elements differ from the corresponding HP IRES elements but in which the core pseudoknot, domain IIId, and domain IIIe elements are all closely related. These findings suggest that HP-like IRESs have been exchanged between unrelated virus families by recombination and support the hypothesis that RNA viruses consist of modular coding and noncoding elements that can exchange and evolve independently. PMID:17392358
Cordes, Nikolaus L.; Seshadri, Srivatsan; Havrilla, George J.; Yuan, Xiaoli; Feser, Michael; Patterson, Brian M.
2015-01-01
Current non-destructive elemental characterization methods, such as scanning electron microscopy-based energy dispersive spectroscopy (SEM–EDS) and micro-X-ray fluorescence spectroscopy (MXRF), are limited to either elemental identification at the surface (SEM–EDS) or suffer from an inability to discriminate between surface or depth information (MXRF). Thus, a non-destructive elemental characterization of individual embedded particles beneath the surface is impossible with either of these techniques. This limitation can be overcome by using laboratory-based 3D confocal micro-X-ray fluorescence spectroscopy (confocal MXRF). This technique utilizes focusing optics on the X-ray source and detector which allows for spatial discrimination in all three dimensions. However, the voxel-by-voxel serial acquisition of a 3D elemental scan can be very time-intensive (~ 1 to 4 weeks) if it is necessary to locate individual embedded particles of interest. As an example, if each point takes a 5 s measurement time, a small volume of 50 × 50 × 50 pixels leads to an acquisition time of approximately 174 h, not including sample stage movement time. Initially screening the samples for particles of interest using micro-X-ray computed tomography (micro-CT) can significantly reduce the time required to spatially locate these particles. Once located, these individual particles can be elementally characterized with confocal MXRF. Herein, we report the elemental identification of high atomic number surface and subsurface particles embedded in a mineralogical matrix by coupling micro-CT and confocal MXRF. Synergistically, these two X-ray based techniques first rapidly locate and then elementally identify individual subsurface particles. - Highlights: • Coupling of confocal X-ray fluorescence spectroscopy and X-ray computed tomography • Qualitative elemental identification of surface and subsurface mineral particles • Non-destructive particle size measurements • Utilization of
Cordes, Nikolaus L., E-mail: ncordes@lanl.gov [Polymers and Coatings Group, Material Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Seshadri, Srivatsan, E-mail: srivatsan.seshadri@zeiss.com [Carl Zeiss X-ray Microscopy, Inc., Pleasanton, CA 94588 (United States); Havrilla, George J. [Chemical Diagnostics and Engineering, Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Yuan, Xiaoli [Julius Kruttschnitt Mineral Research Centre, University of Queensland, Indooroopilly, Brisbane, QLD 4068 (Australia); Feser, Michael [Carl Zeiss X-ray Microscopy, Inc., Pleasanton, CA 94588 (United States); Patterson, Brian M. [Polymers and Coatings Group, Material Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)
2015-01-01
Current non-destructive elemental characterization methods, such as scanning electron microscopy-based energy dispersive spectroscopy (SEM–EDS) and micro-X-ray fluorescence spectroscopy (MXRF), are limited to either elemental identification at the surface (SEM–EDS) or suffer from an inability to discriminate between surface or depth information (MXRF). Thus, a non-destructive elemental characterization of individual embedded particles beneath the surface is impossible with either of these techniques. This limitation can be overcome by using laboratory-based 3D confocal micro-X-ray fluorescence spectroscopy (confocal MXRF). This technique utilizes focusing optics on the X-ray source and detector which allows for spatial discrimination in all three dimensions. However, the voxel-by-voxel serial acquisition of a 3D elemental scan can be very time-intensive (~ 1 to 4 weeks) if it is necessary to locate individual embedded particles of interest. As an example, if each point takes a 5 s measurement time, a small volume of 50 × 50 × 50 pixels leads to an acquisition time of approximately 174 h, not including sample stage movement time. Initially screening the samples for particles of interest using micro-X-ray computed tomography (micro-CT) can significantly reduce the time required to spatially locate these particles. Once located, these individual particles can be elementally characterized with confocal MXRF. Herein, we report the elemental identification of high atomic number surface and subsurface particles embedded in a mineralogical matrix by coupling micro-CT and confocal MXRF. Synergistically, these two X-ray based techniques first rapidly locate and then elementally identify individual subsurface particles. - Highlights: • Coupling of confocal X-ray fluorescence spectroscopy and X-ray computed tomography • Qualitative elemental identification of surface and subsurface mineral particles • Non-destructive particle size measurements • Utilization of
Limbert, G.; Lierde, C. van; Muraru, O.L.; Walboomers, X.F.; Frank, M.; Hansson, S.; Middleton, J.; Jaecques, S.
2010-01-01
The first objective of this computational study was to assess the strain magnitude and distribution within the three-dimensional (3D) trabecular bone structure around an osseointegrated dental implant loaded axially. The second objective was to investigate the relative micromotions between the
Toma, C.; Alexa, Al.; Craciunescu, T.; Pirvan, M.; Dobrin, R.
2008-01-01
In this paper there are presented the results of nondestructive examination in Post Irradiation Examination Laboratory for twenty five fuel rods selected from 14 MW steady state core. Gamma scanning and dimensional measurements were carried out in order to determine burn-up and diametric deflection of the fuel rods. Also, some comparisons with SSR Safety Report estimations for the maximum burn-up pin were made. (authors)
Gamble, Kyle A., E-mail: Kyle.Gamble@inl.gov [Royal Military College of Canada, Chemistry and Chemical Engineering, 13 General Crerar Crescent, Kingston, Ontario, Canada K7K 7B4 (Canada); Williams, Anthony F., E-mail: Tony.Williams@cnl.ca [Canadian Nuclear Laboratories, Fuel and Fuel Channel Safety, 1 Plant Road, Chalk River, Ontario, Canada K0J 1J0 (Canada); Chan, Paul K., E-mail: Paul.Chan@rmc.ca [Royal Military College of Canada, Chemistry and Chemical Engineering, 13 General Crerar Crescent, Kingston, Ontario, Canada K7K 7B4 (Canada); Wowk, Diane, E-mail: Diane.Wowk@rmc.ca [Royal Military College of Canada, Mechanical and Aerospace Engineering, 13 General Crerar Crescent, Kingston, Ontario, Canada K7K 7B4 (Canada)
2015-11-15
Highlights: • This is the first demonstration of using the MOOSE framework for modeling CANDU fuel. • Glued and frictionless contact algorithms behave as expected for 2D and 3D cases. • MOOSE accepts and correctly interprets functions of arbitrary form. • 3D deformation calculations accurately compare against analytical solutions. • MOOSE is a viable simulation tool for modeling accident reactor conditions. - Abstract: Horizontally oriented fuel bundles, such as those in CANada Deuterium Uranium (CANDU) reactors present unique modeling challenges. After long irradiation times or during severe transients the fuel elements can laterally deform out of plane due to processes known as bow and sag. Bowing is a thermally driven process that causes the fuel elements to laterally deform when a temperature gradient develops across the diameter of the element. Sagging is a coupled mechanical and thermal process caused by deformation of the fuel pin due to creep mechanisms of the sheathing after long irradiation times and or high temperatures. These out-of-plane deformations can lead to reduced coolant flow and a reduction in coolability of the fuel bundle. In extreme cases element-to-element or element-to-pressure tube contact could occur leading to reduced coolant flow in the subchannels or pressure tube rupture leading to a loss of coolant accident. This paper evaluates the capability of the Multiphysics Object-Oriented Simulation Environment (MOOSE) framework developed at the Idaho National Laboratory to model these deformation mechanisms. The material model capabilities of MOOSE and its ability to simulate contact are also investigated.
Williams, M.M.R.; Hall, S.K.; Eaton, M.D.
2014-01-01
Highlights: • A rectangular reactor cell with an elliptical fuel element. • Solution of transport and diffusion equations by Fourier expansion. • Numerical examples showing convergence. • Two group cell problems. - Abstract: A method for solving the diffusion and transport equations in a rectangular lattice cell with an elliptical fuel element has been developed using a Fourier expansion of the neutron flux. The method is applied to a one group model with a source in the moderator. The cell flux is obtained and also the associated disadvantage factor. In addition to the one speed case, we also consider the two group equations in the cell which now become an eigenvalue problem for the lattice multiplication factor. The method of solution relies upon an efficient procedure to solve a large set of simultaneous linear equations and for this we use the IMSL library routines. Our method is compared with the results from a finite element code. The main drawback of the problem arises from the very large number of terms required in the Fourier series which taxes the storage and speed of the computer. Nevertheless, useful solutions are obtained in geometries that would normally require the use of finite element or analogous methods, for this reason the Fourier method is useful for comparison with that type of numerical approach. Extension of the method to more intricate fuel shapes, such as stars and cruciforms as well as superpositions of these, is possible
Fernandes, A.; Maiorino, J.R.
1989-01-01
This work presents a method to solve the neutron transport equation in thre space dimensions. The angular flux is aproximated by spherical harmonics and the finite element method is applied to the space component. The program originated by the analytical development is being tested and some results are presented. (author) [pt
Eraslan, A.H.
1975-02-01
A far-field mathematical model is presented for numerical simulation of short-time (within tidal cycle) transient, two-dimensional temperature distributions in large coastal and offshore regions resulting from the condenser cooling water discharges of power plants. The Eulerian FLIDE (fluid-in-discrete-element) formulation employs the integral forms of the conservation principles for mass and thermal energy in variable-sized discrete elements that span the specific flow region. The contributions of vertical variations of the velocity components and temperature are rigorously incorporated in the development of depth-averaged, two-dimensional energy transport fluxes by spatially integrating the conservation equations over the enclosure surfaces of the discrete elements. The general mathematical formulation considers completely arbitrary, transient oceanic flow conditions, which include periodic tidal, geostrophic, and wind-induced currents, as locally specified inputs to the model. The thermal impact of a hypothetical, multiunit generating station in a coastal region is analyzed where the oceanic flow conditions are assumed to be strictly periodic tidal currents within any appreciable net drift of sufficient duration to remove the heated effluent. The numerical simulation indicates that the periodic flow conditions cause considerable variations in the temperature distributions during the day and the tidal cycles, which result in severe recirculation and re-entrainment of the heated water between the intakes and the discharges of the different units. This leads to a gradual, long-term increase of the temperatures in the immediate vicinity of the discharge structures and also in the far-field zone. (U.S.)
Fermionic bound states in distinct kinklike backgrounds
Bazeia, D. [Universidade Federal da Paraiba, Departamento de Fisica, Joao Pessoa, Paraiba (Brazil); Mohammadi, A. [Universidade Federal de Campina Grande, Departamento de Fisica, Caixa Postal 10071, Campina Grande, Paraiba (Brazil)
2017-04-15
This work deals with fermions in the background of distinct localized structures in the two-dimensional spacetime. Although the structures have a similar topological character, which is responsible for the appearance of fractionally charged excitations, we want to investigate how the geometric deformations that appear in the localized structures contribute to the change in the physical properties of the fermionic bound states. We investigate the two-kink and compact kinklike backgrounds, and we consider two distinct boson-fermion interactions, one motivated by supersymmetry and the other described by the standard Yukawa coupling. (orig.)
Zhang, Yijun; Cheng, Yang-Tse; Grummon, David S.
2007-01-01
Indentation-induced shape memory and superelastic effects are recently discovered thermo-mechanical behaviors that may find important applications in many areas of science and engineering. Theoretical understanding of these phenomena is challenging because both martensitic phase transformation and slip plasticity exist under complex contact loading conditions. In this paper, we develop a three-dimensional constitutive model of shape memory alloys with plasticity. Spherical indentation-induced superelasticity in a NiTi shape memory alloy was simulated and compared to experimental results on load-displacement curves and recovery ratios. We show that shallow indents have complete recovery upon unloading, where the size of the phase transformation region is about two times the contact radius. Deep indents have only partial recovery when plastic deformation becomes more prevalent in the indent-affected zone
Sakhel, Asaad R.; Sakhel, Roger R.
2018-02-01
We examine the dynamics of a one-dimensional harmonically trapped Bose-Einstein condensate (BEC), induced by the addition of a dimple trap whose depth oscillates with time. For this purpose, the Lagrangian variational method (LVM) is applied to provide the required analytical equations. The goal is to provide an analytical explanation for the quasiperiodic oscillations of the BEC size at resonance, that is additional to the one given by Adhikari (J Phys B At Mol Opt Phys 36:1109, 2003). It is shown that LVM is able to reproduce instabilities in the dynamics along the same lines outlined by Lellouch et al. (Phys Rev X 7:021015, 2017). Moreover, it is found that at resonance the energy dynamics display ordered oscillations, whereas at off-resonance they tend to be chaotic. Further, by using the Poincare-Lindstedt method to solve the LVM equation of motion, the resulting solution is able to reproduce the quasiperiodic oscillations of the BEC.
Kordy, M. A.; Wannamaker, P. E.; Maris, V.; Cherkaev, E.; Hill, G. J.
2014-12-01
We have developed an algorithm for 3D simulation and inversion of magnetotelluric (MT) responses using deformable hexahedral finite elements that permits incorporation of topography. Direct solvers parallelized on symmetric multiprocessor (SMP), single-chassis workstations with large RAM are used for the forward solution, parameter jacobians, and model update. The forward simulator, jacobians calculations, as well as synthetic and real data inversion are presented. We use first-order edge elements to represent the secondary electric field (E), yielding accuracy O(h) for E and its curl (magnetic field). For very low frequency or small material admittivity, the E-field requires divergence correction. Using Hodge decomposition, correction may be applied after the forward solution is calculated. It allows accurate E-field solutions in dielectric air. The system matrix factorization is computed using the MUMPS library, which shows moderately good scalability through 12 processor cores but limited gains beyond that. The factored matrix is used to calculate the forward response as well as the jacobians of field and MT responses using the reciprocity theorem. Comparison with other codes demonstrates accuracy of our forward calculations. We consider a popular conductive/resistive double brick structure and several topographic models. In particular, the ability of finite elements to represent smooth topographic slopes permits accurate simulation of refraction of electromagnetic waves normal to the slopes at high frequencies. Run time tests indicate that for meshes as large as 150x150x60 elements, MT forward response and jacobians can be calculated in ~2.5 hours per frequency. For inversion, we implemented data space Gauss-Newton method, which offers reduction in memory requirement and a significant speedup of the parameter step versus model space approach. For dense matrix operations we use tiling approach of PLASMA library, which shows very good scalability. In synthetic
Hadi Asgharzadeh Shirazi
2014-06-01
Full Text Available Background and Aims: Hydroxyapatite coating has allocated a special place in dentistry due to its biocompatibility and bioactivity. The purpose of this study was to evaluate the relation between the hydroxyapatite thickness and stress distribution by using finite element method. Materials and Methods: In this paper, the effect of hydroxyapatite coating thickness on dental implants was studied using finite element method in the range between 0 to 200 microns. A 3D model including one section of mandible bone was modeled by a thick layer of cortical surrounding dense cancellous and a Nobel Biocare commercial brand dental implant was simulated and analyzed under static load in the Abaqus software. Results The diagram of maximum von Mises stress versus coating thickness was plotted for the cancellous and cortical bones in the range between 0 to 200 microns. The obtained results showed that the magnitude of maximum von Mises stress of bone decreased as the hydroxyapatite coating thickness increased. Also, the thickness of coating exhibited smoother stress distribution and milder variations of maximum von Mises stress in a range between 60 to 120 microns. Conclusion: In present study, the stress was decreased in the mandible bone where hydroxyapatite coating was used. This stress reduction leads to a faster stabilization and fixation of implant in the mandible bone. Using hydroxyapatite coating as a biocompatible and bioactive material could play an important role in bone formation of implant- bone interface.
Savoldelli, Charles; Bouchard, Pierre-Olivier; Loudad, Raounak; Baque, Patrick; Tillier, Yannick
2012-07-01
This study aims at analysing the stresses distribution in the temporomandibular joint (TMJ) using a complete high-resolution finite element model (FE Model). This model is used here to analyse the stresses distribution in the discs during a closing jaw cycle. In the end, this model enables the prediction of the stress evolution in the TMJ disc submitted to various loadings induced by mandibular trauma, surgery or parafunction. The geometric data for the model were obtained from MRI and CT scans images of a healthy male patient. Surface and volume meshes were successively obtained using a 3D image segmentation software (AMIRA(®)). Bone components of skull and mandible, both of joint discs, temporomandibular capsules and ligaments and dental arches were meshed as separate bodies. The volume meshes were transferred to the FE analysis software (FORGE(®)). Material properties were assigned for each region. Boundary conditions for closing jaw simulations were represented by different load directions of jaws muscles. The von Mises stresses distribution in both joint discs during closing conditions was analyzed. The pattern of von Mises stresses in the TMJ discs is non-symmetric and changed continuously during jaw movement. Maximal stress is reached on the surface disc in areas in contact with others bodies. The three-dimension finite element model of masticatory system will make it possible to simulate different conditions that appear to be important in the cascade of events leading to joint damage.
Gureghian, A.B.
1979-01-01
A mathematical model of ground water transport through an aquifer is presented. The solute of interest is a metal tracer or radioactive material which may undergo decay through a sorbing unconfined aquifer. The subject is developed under the following headings: flow equation, solute equation, boundary conditions, finite element formulation, element formulation, solution scheme (flow equation, solute equation), results and discussions, water movement in a ditch drained aquifer under transient state, water and solute movement in a homogeneous and unsaturated soil, transport of 226 Ra in nonhomogeneous aquifer, tailings pond lined, and tailings pond unlined. It is concluded that this mathematical model may have a wide variety of applications. The uranium milling industry may find it useful to evaluate the hydrogeological suitability of their disposal sites. It may prove suited for the design of clay disposal ponds destined to hold hazardous liquids. It may also provide a means of estimating the long-term impact of radionuclides or other pollutants on the quality of ground water. 31 references, 9 figures, 3 tables
Rozilene Maria Cota Aroeira
2017-05-01
Full Text Available Abstract Introduction: Biomedical studies involve complex anatomical structures, which require specific methodology to generate their geometric models. The middle segment of the thoracic spine (T5-T10 is the site of the highest incidence of vertebral deformity in adolescents. Traditionally, its geometries are derived from computed tomography or magnetic resonance imaging data. However, this approach may restrict certain studies. The study aimed to generate two 3D geometric model of the T5-T10 thoracic spine segment, obtained from graphical images, and to create mesh for finite element studies. Methods A 3D geometric model of T5-T10 was generated using two anatomical images of T6 vertebra (side and top. The geometric model was created in Autodesk® Maya® 3D 2013, and the mesh process in HiperMesh and MeshMixer (v11.0.544 Autodesk. Results The T5-T10 thoracic segment model is presented with its passive components, bones, intervertebral discs and flavum, intertransverse and supraspinous ligaments, in different views, as well as the volumetric mesh. Conclusion The 3D geometric model generated from graphical images is suitable for application in non-patient-specific finite element model studies or, with restrictions, in the use of computed tomography or magnetic resonance imaging. This model may be useful for biomechanical studies related to the middle thoracic spine, the most vulnerable site for vertebral deformations.
Element-topology-independent preconditioners for parallel finite element computations
Park, K. C.; Alexander, Scott
1992-01-01
A family of preconditioners for the solution of finite element equations are presented, which are element-topology independent and thus can be applicable to element order-free parallel computations. A key feature of the present preconditioners is the repeated use of element connectivity matrices and their left and right inverses. The properties and performance of the present preconditioners are demonstrated via beam and two-dimensional finite element matrices for implicit time integration computations.
Demerdash, N. A.; Wang, R.; Secunde, R.
1992-01-01
A 3D finite element (FE) approach was developed and implemented for computation of global magnetic fields in a 14.3 kVA modified Lundell alternator. The essence of the new method is the combined use of magnetic vector and scalar potential formulations in 3D FEs. This approach makes it practical, using state of the art supercomputer resources, to globally analyze magnetic fields and operating performances of rotating machines which have truly 3D magnetic flux patterns. The 3D FE-computed fields and machine inductances as well as various machine performance simulations of the 14.3 kVA machine are presented in this paper and its two companion papers.
Collins, Jeffery D.; Volakis, John L.; Jin, Jian-Ming
1990-01-01
A new technique is presented for computing the scattering by 2-D structures of arbitrary composition. The proposed solution approach combines the usual finite element method with the boundary-integral equation to formulate a discrete system. This is subsequently solved via the conjugate gradient (CG) algorithm. A particular characteristic of the method is the use of rectangular boundaries to enclose the scatterer. Several of the resulting boundary integrals are therefore convolutions and may be evaluated via the fast Fourier transform (FFT) in the implementation of the CG algorithm. The solution approach offers the principal advantage of having O(N) memory demand and employs a 1-D FFT versus a 2-D FFT as required with a traditional implementation of the CGFFT algorithm. The speed of the proposed solution method is compared with that of the traditional CGFFT algorithm, and results for rectangular bodies are given and shown to be in excellent agreement with the moment method.
Yan, Beichuan; Regueiro, Richard A.
2018-02-01
A three-dimensional (3D) DEM code for simulating complex-shaped granular particles is parallelized using message-passing interface (MPI). The concepts of link-block, ghost/border layer, and migration layer are put forward for design of the parallel algorithm, and theoretical scalability function of 3-D DEM scalability and memory usage is derived. Many performance-critical implementation details are managed optimally to achieve high performance and scalability, such as: minimizing communication overhead, maintaining dynamic load balance, handling particle migrations across block borders, transmitting C++ dynamic objects of particles between MPI processes efficiently, eliminating redundant contact information between adjacent MPI processes. The code executes on multiple US Department of Defense (DoD) supercomputers and tests up to 2048 compute nodes for simulating 10 million three-axis ellipsoidal particles. Performance analyses of the code including speedup, efficiency, scalability, and granularity across five orders of magnitude of simulation scale (number of particles) are provided, and they demonstrate high speedup and excellent scalability. It is also discovered that communication time is a decreasing function of the number of compute nodes in strong scaling measurements. The code's capability of simulating a large number of complex-shaped particles on modern supercomputers will be of value in both laboratory studies on micromechanical properties of granular materials and many realistic engineering applications involving granular materials.
Luo, Danmei; Rong, Qiguo; Chen, Quan
2017-09-01
Reconstruction of segmental defects in the mandible remains a challenge for maxillofacial surgery. The use of porous scaffolds is a potential method for repairing these defects. Now, additive manufacturing techniques provide a solution for the fabrication of porous scaffolds with specific geometrical shapes and complex structures. The goal of this study was to design and optimize a three-dimensional tetrahedral titanium scaffold for the reconstruction of mandibular defects. With a fixed strut diameter of 0.45mm and a mean cell size of 2.2mm, a tetrahedral structural porous scaffold was designed for a simulated anatomical defect derived from computed tomography (CT) data of a human mandible. An optimization method based on the concept of uniform stress was performed on the initial scaffold to realize a minimal-weight design. Geometric and mechanical comparisons between the initial and optimized scaffold show that the optimized scaffold exhibits a larger porosity, 81.90%, as well as a more homogeneous stress distribution. These results demonstrate that tetrahedral structural titanium scaffolds are feasible structures for repairing mandibular defects, and that the proposed optimization scheme has the ability to produce superior scaffolds for mandibular reconstruction with better stability, higher porosity, and less weight. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.
Park, Na-Ra; Ahn, Dong-Gyu; Oh, Jin-Woo
2014-01-01
The research on a thermal stress control layer (TSCL) begins to undertake to reduce residual stress and strain in the vicinity of the joined region between the hardfacing layer and the base part. The goal of this paper is to estimate the material combination and the thickness of TSCL for the Stellite21 hardfaced STD61 hot working tool steel via three-dimensional finite element analysis (FEA). TSCL is created by the combination of Stellite21 and STD61. The thickness of TSCL ranges from 0.5 mm to 1.5 mm. The influence of the material combination and the thickness of TSCL on temperature, thermal stress and thermal strain distributions of the hardfaced part have been investigated. The results of the investigation have been revealed that a proper material combination of TSCL is Stellite21 of 50 % and STD61 of 50 %, and its appropriate thickness is 1.0 mm
Li, Le; Wang, Li-yong
2018-04-01
The application of accurate constitutive relationship in finite element simulation would significantly contribute to accurate simulation results, which plays a critical role in process design and optimization. In this investigation, the true stress-strain data of 3Cr20Ni10W2 heat-resisting alloy were obtained from a series of isothermal compression tests conducted in a wide temperature range of 1203-1403 K and strain rate range of 0.01-10 s-1 on a Gleeble 1500 testing machine. Then the constitutive relationship was modeled by an optimally constructed and well-trained back-propagation artificial neural network (BP-ANN). The evaluation of the BP-ANN model revealed that it has admirable performance in characterizing and predicting the flow behaviors of 3Cr20Ni10W2 heat-resisting alloy. Meanwhile, a comparison between improved Arrhenius-type constitutive equation and BP-ANN model shows that the latter has higher accuracy. Consequently, the developed BP-ANN model was used to predict abundant stress-strain data beyond the limited experimental conditions and construct the three-dimensional continuous response relationship for temperature, strain rate, strain, and stress. Finally, the three-dimensional continuous response relationship was applied to the numerical simulation of isothermal compression tests. The results show that such constitutive relationship can significantly promote the accuracy improvement of numerical simulation for hot forming processes.
Two-dimensional NMR spectrometry
Farrar, T.C.
1987-01-01
This article is the second in a two-part series. In part one (ANALYTICAL CHEMISTRY, May 15) the authors discussed one-dimensional nuclear magnetic resonance (NMR) spectra and some relatively advanced nuclear spin gymnastics experiments that provide a capability for selective sensitivity enhancements. In this article and overview and some applications of two-dimensional NMR experiments are presented. These powerful experiments are important complements to the one-dimensional experiments. As in the more sophisticated one-dimensional experiments, the two-dimensional experiments involve three distinct time periods: a preparation period, t 0 ; an evolution period, t 1 ; and a detection period, t 2
Carvalho, Marco Aurélio; Sotto-Maior, Bruno Salles; Del Bel Cury, Altair Antoninha; Pessanha Henriques, Guilherme Elias
2014-11-01
Although various abutment connections and materials have recently been introduced, insufficient data exist regarding the effect of stress distribution on their mechanical performance. The purpose of this study was to investigate the effect of different abutment materials and platform connections on stress distribution in single anterior implant-supported restorations with the finite element method. Nine experimental groups were modeled from the combination of 3 platform connections (external hexagon, internal hexagon, and Morse tapered) and 3 abutment materials (titanium, zirconia, and hybrid) as follows: external hexagon-titanium, external hexagon-zirconia, external hexagon-hybrid, internal hexagon-titanium, internal hexagon-zirconia, internal hexagon-hybrid, Morse tapered-titanium, Morse tapered-zirconia, and Morse tapered-hybrid. Finite element models consisted of a 4×13-mm implant, anatomic abutment, and lithium disilicate central incisor crown cemented over the abutment. The 49 N occlusal loading was applied in 6 steps to simulate the incisal guidance. Equivalent von Mises stress (σvM) was used for both the qualitative and quantitative evaluation of the implant and abutment in all the groups and the maximum (σmax) and minimum (σmin) principal stresses for the numerical comparison of the zirconia parts. The highest abutment σvM occurred in the Morse-tapered groups and the lowest in the external hexagon-hybrid, internal hexagon-titanium, and internal hexagon-hybrid groups. The σmax and σmin values were lower in the hybrid groups than in the zirconia groups. The stress distribution concentrated in the abutment-implant interface in all the groups, regardless of the platform connection or abutment material. The platform connection influenced the stress on abutments more than the abutment material. The stress values for implants were similar among different platform connections, but greater stress concentrations were observed in internal connections
Soğancı, Gökçe; Yazıcıoğlu, Hüseyin
2016-01-01
Mini dental implants could be an alternative treatment method for prosthetic treatment of edentulous cleft palate. The aim of this study was to analyze stress distribution around the cortical bone and different plans using a varied number of mini dental implants in edentulous unilateral complete cleft palates. Three edentulous maxillary models were modified to create unilateral complete cleft palates. Mini dental implants (2.4 × 15 mm) were located as two mini implants at the premolar region, four mini implants at the premolar and molar region, and six mini implants at the first premolar, second premolar, and first molar regions in the models, respectively. Mucosa, o-ring/ball attachments, and overdentures were simulated. Vertical and horizontal loads of 100 N were applied on both the right and left molar teeth of the overdenture for each model. Maximum and minimum principal stress values and the distribution at cortical bone around the implants and cleft palates were evaluated by finite element analysis. Stress values under vertical loads were lower than values under horizontal loadings for all models. Stress values were found to be lower in the first model than in the second and third models. The highest stress values were found around implants in the second model. The unilateral feature of a complete cleft pattern affected the stress distribution. Stresses occured mostly around implants when the overdenture was supported by six implants; however, the stress distribution around implants was low with two implants because of tissue support.
Mayer, Carl R. [Materials Science and Engineering, Arizona State University, Tempe, AZ 85287-6106 (United States); Molina-Aladareguia, Jon [IMDEA Materials Institute, c/Eric Kandel 2, Getafe, Madrid 28906 (Spain); Chawla, Nikhilesh, E-mail: nchawla@asu.edu [Materials Science and Engineering, Arizona State University, Tempe, AZ 85287-6106 (United States)
2016-10-15
Al-SiC nanolaminate composites show promise as high performance coating materials due to their combination of strength and toughness. Although a significant amount of modeling effort has been focused on materials with an idealized flat nanostructure, experimentally these materials exhibit complex undulating layer geometries. This work utilizes FIB tomography to characterize this nanostructure in 3D and finite element modeling to determine the effect that this complex structure has on the mechanical behavior of these materials. A sufficiently large volume was characterized such that a 1 × 2 μm micropillar could be generated from the dataset and compared directly to experimental results. The mechanical response from this nanostructure was then compared to pillar models using simplified structures with perfectly flat layers, layers with sinusoidal waviness, and layers with arc segment waviness. The arc segment based layer geometry showed the best agreement with the experimentally determined structure, indicating it would be the most appropriate geometry for future modeling efforts. - Highlights: •FIB tomography was used to determine the structure of an Al-SiC nanolaminate in 3D. •FEM was used to compare the deformation of the nanostructure to experimental results. •Idealized structures from literature were compared to the FIB determined structure. •Arc segment based structures approximated the FIB determined structure most closely.
Antic, Svetlana; Vukicevic, Arso M; Milasinovic, Marko; Saveljic, Igor; Jovicic, Gordana; Filipovic, Nenad; Rakocevic, Zoran; Djuric, Marija
2015-07-01
The aim of the present study was to investigate the influences of the presence and position of a lower third molar (M3) on the fragility of mandibular angle and condyle, using finite element analysis. From computed tomographic scans of a human mandible with normally erupted M3, two additional virtual models were generated: a mandibular model with partially impacted M3 and a model without M3. Two cases of impact were considered: a frontal and a lateral blow. The results are based on the chromatic analysis of the distributed von Mises and principal stresses, and calculation of their failure indices. In the frontal blow, the angle region showed the highest stress in the case with partially impacted M3, and the condylar region in the case without M3. Compressive stresses were dominant but caused no failure. Tensile stresses were recorded in the retromolar areas, but caused failure only in the case with partially impacted M3. In the lateral blow, the stress concentrated at the point of impact, in the ipsilateral and contralateral angle and condylar regions. The highest stresses were recorded in the case with partially impacted M3. Tensile stresses caused the failure on the ipsilateral side, whereas compressive stresses on the contralateral side. Copyright © 2015 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.
Pacheco, Ariel Adriano Reyes; Saga, Armando Yukio; de Lima, Key Fonseca; Paese, Victor Nissen; Tanaka, Orlando M
2016-01-01
By using the finite element method (FEM), this study aimed to evaluate the effect of different corticotomy formats on the distribution and magnitude of stress on the periodontal ligament (PDL) during retraction of the maxillary canine. A geometric model of the left hemi-jaw was created from computed tomography scan images of a dry human skull and loads were administered during distalization movement of the canine. Three trials were performed: (1) without corticotomy, (2) box-shaped corticotomy and perforations in the cortical bone of the canine (CVC) and (3) CVC and circular-shaped corticotomy in the cortical bone of the edentulous space of the first premolar. There was no difference in stress distribution among the different corticotomy formats. Different corticotomy formats used to accelerate orthodontic tooth movement did not affect stress distribution in the PDL during canine retraction. From a mechanical perspective, the present study showed that the stress distribution on the PDL during canine retraction was similar in all the corticotomy formats. When using the Andrews T2 bracket, the PDL presented the highest levels of stress in the middle third of the PDL, suggesting that the force was near the center of resistance. Also, as bone weakening by corticotomies did not influence stress distribution, the surgical procedure could be simplified to a less aggressive one, focusing more on inflammatory cellular stimulation than on bone resistance. A simpler surgical act could also be performed by most orthodontists in their practices, enhancing postoperative response and reducing patient costs.
Jason Bourke
Full Text Available Models of the mammalian jaw have predicted that bite force is intimately linked to jaw gape and to tooth position. Despite widespread use, few empirical studies have provided evidence to validate these models in non-human mammals and none have considered the influence of gape angle on the distribution of stress. Here using a multi-property finite element (FE model of Canis lupus dingo, we examined the influence of gape angle and bite point on both bite force and cranial stress. Bite force data in relation to jaw gape and along the tooth row, are in broad agreement with previously reported results. However stress data showed that the skull of C. l. dingo is mechanically suited to withstand stresses at wide gapes; a result that agreed well with previously held views regarding carnivoran evolution. Stress data, combined with bite force information, suggested that there is an optimal bite angle of between 25 degrees and 35 degrees in C. l. dingo. The function of these rather small bite angles remains unclear.
Inui, Chie; Ozaki, Shinsuke; Kura, Hiroaki; Sato, Tetsuya
2011-01-01
Optical and magneto-optical properties of one-dimensional magneto-optical photonic crystal (1-D MPC) prepared by the sol-gel dip-coating method, including a magnetic defect layer composed of mixture of CoFe 2 O 4 and SiO 2 , are investigated from both the experimental and theoretical standpoints. The resonant transmission of light was observed around 570 nm in the photonic band gap. The Faraday rotation angle θ F showed two maxima at 490 and 640 nm, and the wavelength dependence of θ F above 760 nm was similar to that of the CoFe 2 O 4 +SiO 2 single-layer film. The two maxima of θ F are attributed to the enhanced Faraday rotation of nonmagnetic TiO 2 layers in the cavity structure and that in magnetic CoFe 2 O 4 +SiO 2 layer through the light localization in MPC. The maximum value of θ F due to the magnetic CoFe 2 O 4 +SiO 2 layer in the MPC was 22-times larger than that in the single-layer film. The simulation study of MPC with CoFe 2 O 4 +SiO 2 magnetic defect layer, based on the matrix approach method, showed that the resonant light transmission was accompanied by the localization of electric field, and large enhancement of θ F appeared at different wavelengths so as to agree with the experimental features. This can be explained in terms of the wavelength dependent off-diagonal components of the dielectric constant tensor in addition to the large extinction coefficient in the CoFe 2 O 4 +SiO 2 magnetic defect layer. - Highlights: → 1-D magnetic photonic crystal (MPC) prepared by sol-gel method. → Enhancement of Faraday rotation due to the magnetic defect layer of CoFe 2 O 4 . → Shift of wavelength of Faraday rotation maximum from resonant light transmission.
Fujikubo, M.; Yao, T.; Oida, H. [Hiroshima University, Hiroshima (Japan). Faculty of Engineering
1996-12-31
Formulation was made on a one-dimensional beam finite element which is effective in analyzing structural response of very large floating structures by modeling them on beams on an elastic foundation. This element allows strict solution of vibration response in the beams on the elastic foundation to be calculated efficiently for a case where mass and rigidity change in the longitudinal direction. This analysis method was used to analyze structural response of a large pontoon-type floating structure to investigate mass in the end part for the structural response and the effect of decay while passing the structure. With a pontoon-type floating structure, reduction in bends and bending stress in the end part of the floating structure is important in designing the structure. Reducing the mass in the end part is effective as a means to avoid resonance in these responses and reduce the responses. Increase in rigidity of a floating structure shifts the peak in quasi-static response to lower frequency side, and reduces response in resonance, hence it is advantageous for improving the response. Since incident waves decay while passing through the floating structure, response in the lower wave side decreases. The peak frequency in the quasi-static response also decreases at the end part of the structure in the upper wave side due to decay in wave force. 7 refs., 11 figs., 1 tab.
Fujikubo, M; Yao, T; Oida, H [Hiroshima University, Hiroshima (Japan). Faculty of Engineering
1997-12-31
Formulation was made on a one-dimensional beam finite element which is effective in analyzing structural response of very large floating structures by modeling them on beams on an elastic foundation. This element allows strict solution of vibration response in the beams on the elastic foundation to be calculated efficiently for a case where mass and rigidity change in the longitudinal direction. This analysis method was used to analyze structural response of a large pontoon-type floating structure to investigate mass in the end part for the structural response and the effect of decay while passing the structure. With a pontoon-type floating structure, reduction in bends and bending stress in the end part of the floating structure is important in designing the structure. Reducing the mass in the end part is effective as a means to avoid resonance in these responses and reduce the responses. Increase in rigidity of a floating structure shifts the peak in quasi-static response to lower frequency side, and reduces response in resonance, hence it is advantageous for improving the response. Since incident waves decay while passing through the floating structure, response in the lower wave side decreases. The peak frequency in the quasi-static response also decreases at the end part of the structure in the upper wave side due to decay in wave force. 7 refs., 11 figs., 1 tab.
Hsieh Pang-Hsing
2008-06-01
Full Text Available Abstract Background Initial promise of a stand-alone interbody fusion cage to treat chronic back pain and restore disc height has not been realized. In some instances, a posterior spinal fixation has been used to enhance stability and increase fusion rate. In this manuscript, a new stand-alone cage is compared with conventional fixation methods based on the finite element analysis, with a focus on investigating cage-bone interface mechanics and stress distribution on the adjacent tissues. Methods Three trapezoid 8° interbody fusion cage models (dual paralleled cages, a single large cage, or a two-part cage consisting of a trapezoid box and threaded cylinder were created with or without pedicle screws fixation to investigate the relative importance of the screws on the spinal segmental response. The contact stress on the facet joint, slip displacement of the cage on the endplate, and rotational angle of the upper vertebra were measured under different loading conditions. Results Simulation results demonstrated less facet stress and slip displacement with the maximal contact on the cage-bone interface. A stand-alone two-part cage had good slip behavior under compression, flexion, extension, lateral bending and torsion, as compared with the other two interbody cages, even with the additional posterior fixation. However, the two-part cage had the lowest rotational angles under flexion and torsion, but had no differences under extension and lateral bending. Conclusion The biomechanical benefit of a stand-alone two-part fusion cage can be justified. This device provided the stability required for interbody fusion, which supports clinical trials of the cage as an alternative to circumferential fixations.
Kordy, M.; Wannamaker, P.; Maris, V.; Cherkaev, E.; Hill, G.
2016-01-01
Following the creation described in Part I of a deformable edge finite-element simulator for 3-D magnetotelluric (MT) responses using direct solvers, in Part II we develop an algorithm named HexMT for 3-D regularized inversion of MT data including topography. Direct solvers parallelized on large-RAM, symmetric multiprocessor (SMP) workstations are used also for the Gauss-Newton model update. By exploiting the data-space approach, the computational cost of the model update becomes much less in both time and computer memory than the cost of the forward simulation. In order to regularize using the second norm of the gradient, we factor the matrix related to the regularization term and apply its inverse to the Jacobian, which is done using the MKL PARDISO library. For dense matrix multiplication and factorization related to the model update, we use the PLASMA library which shows very good scalability across processor cores. A synthetic test inversion using a simple hill model shows that including topography can be important; in this case depression of the electric field by the hill can cause false conductors at depth or mask the presence of resistive structure. With a simple model of two buried bricks, a uniform spatial weighting for the norm of model smoothing recovered more accurate locations for the tomographic images compared to weightings which were a function of parameter Jacobians. We implement joint inversion for static distortion matrices tested using the Dublin secret model 2, for which we are able to reduce nRMS to ˜1.1 while avoiding oscillatory convergence. Finally we test the code on field data by inverting full impedance and tipper MT responses collected around Mount St Helens in the Cascade volcanic chain. Among several prominent structures, the north-south trending, eruption-controlling shear zone is clearly imaged in the inversion.
1983-04-01
VISCOT is a non-linear, transient, thermal-stress finite-element code designed to determine the viscoelastic, fiscoplastic, or elastoplastic deformation of a rock mass due to mechanical and thermal loading. The numerical solution of the nonlinear incremental equilibrium equations within VISCOT is performed by using an explicit Euler time-stepping scheme. The rock mass may be modeled as a viscoplastic or viscoelastic material. The viscoplastic material model can be described by a Tresca, von Mises, Drucker-Prager or Mohr-Coulomb yield criteria (with or without strain hardening) with an associated flow rule which can be a power or an exponential law. The viscoelastic material model within VISCOT is a temperature- and stress-dependent law which has been developed specifically for salt rock masses by Pfeifle, Mellegard and Senseny in ONWI-314 topical report (1981). Site specific parameters for this creep law at the Richton, Permian, Paradox and Vacherie salt sites have been calculated and are given in ONWI-314 topical report (1981). A major application of VISCOT (in conjunction with a SCEPTER heat transfer code such as DOT) is the thermomechanical analysis of a rock mass such as salt in which significant time-dependent nonlinear deformations are expected to occur. Such problems include room- and canister-scale studies during the excavation, operation, and long-term post-closure stages in a salt repository. In Section 1.5 of this document the code custodianship and control is described along with the status of verification, validation and peer review of this report
Prakash Vijay
2009-01-01
Full Text Available Context: Bar overdentures are popular choices among clinicians worldwide but configurations that provide an optimal biomechanical distribution of stress are still debatable. Aims: To compare the stresses and elastic flexion between implant supported bar overdentures in various configurations using finite element analysis. Settings and Design: A CAT scan of a human mandible was used to generate an anatomically accurate mechanical model. Materials and Methods: Three models with bars and clips in three different configurations were constructed. Model 1 had a single bar connecting two implants, Model 2 had three bars connecting all the four implants, and Model 3 had two bars connecting the medial and distal implants on the sides only. The models were loaded under static conditions with 100N load distributed at the approximate position of the clip. The mandibular boundary conditions were modeled considering the real geometry of its muscle supporting system. Maximum von Mises stress at the level of the bar and at the bone implant interface were compared in all three models. The flexion of mandible and the bar was also compared qualitatively. Statistical Analysis Used: The analyses were accomplished using the ANSYS software program and were processed by a personal computer. Stress on these models was analyzed after loading conditions. Results: Qualitative comparisons showed that stress at the level of the bar and at the bone implant interface were in the following order: Model 1> Model 3> Model 2. The flexion of the mandible and the bar were in the following order: Model 2 > Model 1 > Model 3. Conclusions: Four implant bar systems connected by bars on the sides only is a better choice than two implant bar systems and four implant bar systems with bars connecting all four implants.
NONE
1991-04-01
Research, development and evaluation were performed with an objective of establishing the basic technology related to three-dimensional circuit elements that integrate functions at ultra-high density. For the basic technology of lamination, the SOI technology suitable for the three-dimensional circuit elements was developed, and it has become possible to manufacture high-quality multi-layered crystalline structure by means of annealing that uses laser and electron beam. In addition, a lateral epitaxial technology for solid phase was developed, and the base to be applied to the three-dimensional circuit elements was established. Furthermore, the technology to put thin film circuits together would be useful for high-density integration in the future. The three-dimensional circuit makes parallel processing in each segment possible, whereas a possibility was shown that the processing can be performed at much higher speed than before. Actually a prototype three-dimensional circuit equipped with functions for parallel processing and judgment processing was fabricated. The image pre-processing which has been impossible on the real time basis in the conventional two-dimensional integrated circuit was realized in a speed as fast as milli-second order. These achievements lead to a belief that the targets for the present research and development have been achieved. (NEDO)
Touch communicates distinct emotions.
Hertenstein, Matthew J; Keltner, Dacher; App, Betsy; Bulleit, Brittany A; Jaskolka, Ariane R
2006-08-01
The study of emotional signaling has focused almost exclusively on the face and voice. In 2 studies, the authors investigated whether people can identify emotions from the experience of being touched by a stranger on the arm (without seeing the touch). In the 3rd study, they investigated whether observers can identify emotions from watching someone being touched on the arm. Two kinds of evidence suggest that humans can communicate numerous emotions with touch. First, participants in the United States (Study 1) and Spain (Study 2) could decode anger, fear, disgust, love, gratitude, and sympathy via touch at much-better-than-chance levels. Second, fine-grained coding documented specific touch behaviors associated with different emotions. In Study 3, the authors provide evidence that participants can accurately decode distinct emotions by merely watching others communicate via touch. The findings are discussed in terms of their contributions to affective science and the evolution of altruism and cooperation. (c) 2006 APA, all rights reserved
Standard elements; Elements standards
Blanc, B [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires
1958-07-01
Following his own experience the author recalls the various advantages, especially in the laboratory, of having pre-fabricated vacuum-line components at his disposal. (author) [French] A la suite de sa propre experience, l'auteur veut rappeler les divers avantages que presente, tout particulierement en laboratoire, le fait d'avoir a sa disposition des elements pre-fabriques de canalisations a vide. (auteur)
Lee, Ki-Sun; Shin, Sang-Wan; Lee, Sang-Pyo; Kim, Jong-Eun; Kim, Jee-Hwan; Lee, Jeong-Yol
The purpose of this pilot study was to evaluate and compare polyetherketoneketone (PEKK) with different framework materials for implant-supported prostheses by means of a three-dimensional finite element analysis (3D-FEA) based on cone beam computed tomography (CBCT) and computer-aided design (CAD) data. A geometric model that consisted of four maxillary implants supporting a prosthesis framework was constructed from CBCT and CAD data of a treated patient. Three different materials (zirconia, titanium, and PEKK) were selected, and their material properties were simulated using FEA software in the generated geometric model. In the PEKK framework (ie, low elastic modulus) group, the stress transferred to the implant and simulated adjacent tissue was reduced when compressive stress was dominant, but increased when tensile stress was dominant. This study suggests that the shock-absorbing effects of a resilient implant-supported framework are limited in some areas and that rigid framework material shows a favorable stress distribution and safety of overall components of the prosthesis.
Kaku, Nobuhiro; Tabata, Tomonori; Tsumura, Hiroshi
2015-12-01
We verified the index cup position required for bulk bone grafting instead of morcellized grafting immediately after cementless total hip arthroplasty. Three-dimensional finite element analysis was used to evaluate changes in the volume of the slippage of the cup-host bone interface as micro-motion of the cup at the acetabular bone defect site depending on the cup-center-edge (CE) angle. The conditions of bulk bone grafts were similar to those of cortical bone. Slippage increased with decreasing cup-CE angle. A bulk bone graft tightly fixed to the host bone prevented considerably larger slippage between the cup and host bone. A smaller cup-CE angle increased the impact of the bulk bone graft on slippage. When the cup-CE angle was 0° or -10°, the criterion for slippage in favorable initial fixation in all conditions was cup and bone graft, it is impossible to obtain reliable fixation of the cup with a cup-CE angle cup-host bone fixation, especially when the cup-CE angle is small, such as cups, and sufficient fixation between the host bone and cup or bulk bone graft using a screw is effective when the cup-CE angle is extremely small.
Galvanic element. Galvanisches Element
Sprengel, D.; Haelbig, H.
1980-01-03
The invention concerns a gas-tight sealed accumulator with positive and negative electrode plates and an auxillary electrode electroconductively bound to the latter for suppressing oxygen pressure. The auxillary electrode is an intermediate film electrode. The film catalysing oxygen reduction is hydrophilic in character and the other film is hydrophobic. A double coated foil has proved to be advantageous, the hydrophilic film being formed from polymer-bound activated carbon and the hydrophrobic film from porous polytetrafluoroethylene. A metallic network of silver or nickel is rolled into the outer side of the activated carbon film. This auxillary electrode can be used to advantage in all galvanic elements. Even primary cells fall within the scope of application for auxillary electrodes because many of these contain a highly oxidized electrodic material which tends to give off oxygen.
A set of pathological tests to validate new finite elements
M. Senthilkumar (Newgen Imaging) 1461 1996 Oct 15 13:05:22
The finite element method entails several approximations. Hence it ... researchers have designed several pathological tests to validate any new finite element. The .... Three dimensional thick shell elements using a hybrid/mixed formu- lation.
Divergent picornavirus IRES elements
Belsham, Graham
2009-01-01
Internal ribosome entry site (IRES) elements were first identified about 20 years ago within the 5' untranslated region of picornavirus RNAs. They direct a cap-independent mechanism of translation initiation on the viral RNA. Within the picornavirus family it is now known that there are four...... classes of IRES element which vary in size (450-270nt), they also have different, complex, secondary structures and distinct requirements for cellular proteins to allow them to function. This review describes the features of each class of picornavirus IRES element but focuses on the characteristics...... of the most recently described group, initially identified within the porcine teschovirus-1 RNA, which has strong similarities to the IRES elements from within the genomes of hepatitis C virus and the pestiviruses which are members of the flavivirus family. The selection of the initiation codon...
Counselor Identity: Conformity or Distinction?
McLaughlin, Jerry E.; Boettcher, Kathryn
2009-01-01
The authors explore 3 debates in other disciplines similar to counseling's identity debate in order to learn about common themes and outcomes. Conformity, distinction, and cohesion emerged as common themes. They conclude that counselors should retain their distinctive, humanistic approach rather than conforming to the dominant, medical approach.
Amir-Moez, A R; Sneddon, I N
1962-01-01
Elements of Linear Space is a detailed treatment of the elements of linear spaces, including real spaces with no more than three dimensions and complex n-dimensional spaces. The geometry of conic sections and quadric surfaces is considered, along with algebraic structures, especially vector spaces and transformations. Problems drawn from various branches of geometry are given.Comprised of 12 chapters, this volume begins with an introduction to real Euclidean space, followed by a discussion on linear transformations and matrices. The addition and multiplication of transformations and matrices a
Lo, C.Y.; Goldstein, G.R.; Napier, A.
1989-01-01
A unified theory of electromagnetic and gravitational fields should modify classical electrodynamics to account for the radiation reaction force. A conjecture that the radiation reaction force and the Lorentz force should be distinct, but in unified forms, results in a five-dimensional unified theory of five variables. It is found that a semicylindrical condition can reconcile the apparent differences between a five-dimensional physical space and our four-dimensional perceptions. Analysis of the geodesic equations results in the notion of gauge dynamics which manifests the influence of the unrestricted fifth variable. The element g 55 of the five-dimensional metric is identified as the radiation potential, which can directly determine the radiation reaction force. This gives a distinct physical origin for the radiation process in classical theory. The potential suggests that the electron can have excited states in quantum electrodynamics. This theory is supported with calculations which demonstrate that the motion of the fifth variable directly causes physical changes in the four-dimensional subspace
The influence of distinct types of aquatic vegetation on the flow field
Valyrakis, Manousos; Barcroft, Stephen; Yagci, Oral
2014-05-01
The Sustainable management of fluvial systems dealing with flood prevention, erosion protection and restoration of rivers and estuaries requires implementation of soft/green-engineering methods. In-stream aquatic vegetation can be regarded as one of these as it plays an important role for both river ecology (function) and geomorphology (form). The goal of this research is to offer insight gained from pilot experimental studies on the effects of a number of different elements modeling instream, aquatic vegetation on the local flow field. It is hypothesized that elements of the same effective "blockage" area but of distinct characteristics (structure, porosity and flexibility), will affect both the mean and fluctuating levels of the turbulent flow to a different degree. The above hypothesis is investigated through a set of rigorous set of experimental runs which are appropriately designed to assess the variability between the interaction of aquatic elements and flow, both quantitatively and qualitatively. In this investigation three elements are employed to model aquatic vegetation, namely a rigid cylinder, a porous but rigid structure and a flexible live plant (Cupressus Macrocarpa). Firstly, the flow field downstream each of the mentioned elements was measured under steady uniform flow conditions employing acoustic Doppler velocimetry. Three-dimensional flow velocities downstream the vegetation element are acquired along a measurement grid extending about five-fold the element's diameter. These measurements are analyzed to develop mean velocity and turbulent intensity profiles for all velocity components. A detailed comparison between the obtained results is demonstrative of the validity of the above hypothesis as each of the employed elements affects in a different manner and degree the flow field. Then a flow visualization technique, during which fluorescent dye is injected upstream of the element and images are captured for further analysis and comparison, was
2010-01-01
Pr Serge Haroche La Médaille d’or 2009 du CNRS est décernée au Pr Serge Haroche, titulaire de la chaire de Physique quantique depuis 2001. Serge Haroche est spécialiste de physique atomique et d’optique quantique. Il est l’un des fondateurs de l’électrodynamique quantique en cavité, domaine qui permet, par des expériences conceptuellement simples, d’éclairer les fondements de la théorie quantique et de réaliser des prototypes de systèmes de traitement quantique de l’information. Serge Haroche...
Noise-induced drift in two-dimensional anisotropic systems
Farago, Oded
2017-10-01
We study the isothermal Brownian dynamics of a particle in a system with spatially varying diffusivity. Due to the heterogeneity of the system, the particle's mean displacement does not vanish even if it does not experience any physical force. This phenomenon has been termed "noise-induced drift," and has been extensively studied for one-dimensional systems. Here, we examine the noise-induced drift in a two-dimensional anisotropic system, characterized by a symmetric diffusion tensor with unequal diagonal elements. A general expression for the mean displacement vector is derived and presented as a sum of two vectors, depicting two distinct drifting effects. The first vector describes the tendency of the particle to drift toward the high diffusivity side in each orthogonal principal diffusion direction. This is a generalization of the well-known expression for the noise-induced drift in one-dimensional systems. The second vector represents a novel drifting effect, not found in one-dimensional systems, originating from the spatial rotation in the directions of the principal axes. The validity of the derived expressions is verified by using Langevin dynamics simulations. As a specific example, we consider the relative diffusion of two transmembrane proteins, and demonstrate that the average distance between them increases at a surprisingly fast rate of several tens of micrometers per second.
On higher order pyramidal finite elements
Liu, L.; Davies, K.B.; Křížek, Michal; Guan, L.
2011-01-01
Roč. 3, č. 2 (2011), s. 131-140 ISSN 2070-0733 R&D Projects: GA AV ČR(CZ) IAA100190803 Institutional research plan: CEZ:AV0Z10190503 Keywords : pyramidal polynomial basis functions * finite element method * composite elements * three-dimensional mortar elements Subject RIV: BA - General Mathematics Impact factor: 0.750, year: 2011
Sivaramakrishnan, C. K.; Jadhav, A. V.; Reghuraman, K.; Mathew, K. A.; Nair, P. S.; Ramaniah, M. V.
1973-07-01
Research progress is reported on studies of the transplutonium elements including recovery and purification of americium, preparation of /sup 238/Pu, extraction studies using diethylhexyl phosphate. (DHM)
Hajeb, Parvaneh; Shakibazadeh, Shahram; Sloth, Jens Jørgen
2016-01-01
Food is considered the main source of toxic element (arsenic, cadmium, lead, and mercury) exposure to humans, and they can cause major public health effects. In this chapter, we discuss the most important sources for toxic element in food and the foodstuffs which are significant contributors to h...
Defining poverty as distinctively human
H.P.P. Lötter
2007-05-01
Full Text Available While it is relatively easy for most people to identify human beings suffering from poverty, it is rather more difficult to come to a proper understanding of poverty. In this article the author wants to deepen our understanding of poverty by interpreting the conventional definitions of poverty in a new light. The article starts with a defence of a claim that poverty is a concept uniquely applicable to humans. It then present a critical discussion of the distinction between absolute and relative poverty and it is then argued that a revision of this distinction can provide general standards applicable to humans everywhere.
Pipeline robots with elastic elements
A. Matuliauskas
2002-10-01
Full Text Available In the article constructions of the pipeline robots with elastic elements are reviewed and the scheme of new original construction is presented. The mathematical models of a robot with one-dimensional vibration exciter with two degrees of freedom were developed and the equations of movement were formed and written. The mathematical model of the pipeline robot with circular elements is formed and its motion equations are presented.
FINITE ELEMENT ANALYSIS OF ELEMENT ANALYSIS OF A FREE ...
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the stairs and to compare the finite element ana ... tual three dimensional behavior of the stair slab system. ..... due to its close relation of output with the propo .... flights. It is best not to consider any open well when .... thermodynamics of solids.
Dietrich, R.
1984-01-01
The basic concepts of the finite element method are explained. The results are compared to existing calibration curves for such test piece geometries derived using experimental procedures. (orig./HP) [de
Dimensional analysis is a useful tool which finds important applications in physics and engineering. It is most effective when there exist a maximal number of dimensionless quantities constructed out of the relevant physical variables. Though a complete theory of dimen- sional analysis was developed way back in 1914 in a.
ARRINDELL, WA; OEI, TPS; EVANS, L; VANDERENDE, J
1991-01-01
In a recent review article, Arrindell, Pickersgill, Merckelbach, Ardon, and Cornet (1991) (Advances in Behaviour Research and Therapy, 13, 73-130) proposed an a priori four-dimensional categorization system for the description of self-rated fears on the basis of suggestions from previous reviews and
Armijo, J.S.
1976-01-01
A fuel element for nuclear reactors is proposed which has a higher corrosion resisting quality in reactor operations. The zirconium alloy coating around the fuel element (uranium or plutonium compound) has on its inside a protection layer of metal which is metallurgically bound to the substance of the coating. As materials are namned: Alluminium, copper, niobium, stainless steel, and iron. This protective metallic layer has another inner layer, also metallurgically bound to its surface, which consists usually of a zirconium alloy. (UWI) [de
Akimov Pavel
2016-01-01
Full Text Available The distinctive paper is devoted to the two-dimensional semi-analytical solution of boundary problems of analysis of shear walls with the use of discrete-continual finite element method (DCFEM. This approach allows obtaining the exact analytical solution in one direction (so-called “basic” direction, also decrease the size of the problem to one-dimensional common finite element analysis. The resulting multipoint boundary problem for the first-order system of ordinary differential equations with piecewise constant coefficients is solved analytically. The proposed method is rather efficient for evaluation of the boundary effect (such as the stress field near the concentrated force. DCFEM also has a completely computer-oriented algorithm, computational stability, optimal conditionality of resultant system and it is applicable for the various loads at an arbitrary point or a region of the wall.
Fluck, E.; Heumann, K.G.
1985-01-01
Following a recommendation by the International Union for Pure and Applied Chemistry (IUPAC), the groups of the periodic table shall be numbered from 1 to 18, instead of I to VIII as before. The recommendations has been approved of by the Committee on Nomenclature of the American Chemical Society. The new system abandons the distinction between main groups (a) and auxiliary groups (b), which in the past frequently has been the reason for misunderstandings between European and American chemists, due to different handling. The publishing house VCH Verlagsgesellschaft recently produced a new periodic table that shows the old and the new numbering system together at a glance, so that chemists will have time to get familiar with the new system. In addition the new periodic table represents an extensive data compilation arranged by elements. The front page lists the chemical properties of elements, the back page their physical properties. (orig./EF) [de
Tani, Laurits
2015-01-01
To control Peltier elements, temperature controller was used. I used TEC-1091 that was manufactured my Meerstetter Engineering. To gain control with the temperature controller, software had to be intalled on a controlling PC. There were different modes to control the Peltier: Tempererature controller to control temperature, Static current/voltage to control voltage and current and LIVE ON/OFF to auto-tune the controller respectively to the system. Also, since near the collision pipe there is much radiation, radiation-proof Peltier elements have to be used. To gain the best results, I had to find the most efficient Peltier elements and try to get their cold side to -40 degrees Celsius.
Kennedy, S.T.
1982-01-01
A nuclear reactor fuel element wherein a stack of nuclear fuel is prevented from displacement within its sheath by a retainer comprising a tube member which is radially expanded into frictional contact with the sheath by means of a captive ball within a tapered bore. (author)
Hemingway, J.D.
1975-01-01
The review is covered in sections, entitled: predicted nuclear properties - including closed shells, decay characteristics; predicted chemical properties - including electronic structure and calculated properties, X-radiation, extrapolated chemical properties, separation chemistry; methods of synthesis; the natural occurrence of superheavy elements. (U.K.)
Presidential address: distinction or extinction.
Pressman, Barry D
2008-10-01
Despite its continuing scientific successes in imaging, radiology as a specialty is faced with a very difficult and competitive environment. Nonradiologists are more and more interested in vertically integrating imaging into their practices, while teleradiology and picture archiving and communication systems are resulting in the greater isolation of radiologists. Commoditization is a realistic and devastating threat to the survival and professionalism of the specialty. To remain viable as a specialty, radiologists must elevate their practice by subspecializing, becoming more involved with clinical care, and actively interacting with patients and referring clinicians. Distinction will prevent extinction.
Finite-Element Software for Conceptual Design
Lindemann, J.; Sandberg, G.; Damkilde, Lars
2010-01-01
and research. Forcepad is an effort to provide a conceptual design and teaching tool in a finite-element software package. Forcepad is a two-dimensional finite-element application based on the same conceptual model as image editing applications such as Adobe Photoshop or Microsoft Paint. Instead of using...
Flerov, G.
1976-01-01
The history is briefly described of the investigation of superheavy elements at the Joint Institute for Nuclear Research at Dubna. The significance of the investigation is assessed from the point of view of the nuclear structure study and major problems encountered in experimental efforts are indicated. Current experimental methods aiming at the discovery or the production of superheavy nuclei with Z approximately 114 are listed. (I.W.)
A Note on Symplectic, Multisymplectic Scheme in Finite Element Method
GUO Han-Ying; JI Xiao-Mei; LI Yu-Qi; WU Ke
2001-01-01
We find that with uniform mesh, the numerical schemes derived from finite element method can keep a preserved symplectic structure in one-dimensional case and a preserved multisymplectic structure in two-dimensional case respectively. These results are in fact the intrinsic reason why the numerical experiments show that such finite element algorithms are accurate in practice.``
Multi-Dimensional Path Queries
Bækgaard, Lars
1998-01-01
to create nested path structures. We present an SQL-like query language that is based on path expressions and we show how to use it to express multi-dimensional path queries that are suited for advanced data analysis in decision support environments like data warehousing environments......We present the path-relationship model that supports multi-dimensional data modeling and querying. A path-relationship database is composed of sets of paths and sets of relationships. A path is a sequence of related elements (atoms, paths, and sets of paths). A relationship is a binary path...
Yilmaz, C.; Akkas, N.
1979-01-01
In previous studies a fluid element is incorporated in the widely used general purpose finite element program SAPIV. This type of problem is of interest in the design of nuclear components involving geometric complexities and nonlinearities. The elasticity matrix of a general-purpose finite element program is modified in such a way that it becomes possible to idealize fluid as a structural finite element with zero shear modulus and a given bulk modules. Using the modified version of SAPIV, several solid-fluid interactions problems are solved. The numerical solutions are compared with the available analytical solutions. They are shown to be in reasonable aggrement. It is also shown that by solving an exterior-fluid interaction problem, the pressure wave propagation in the acoustic medium can be solved with the same approach. In this study, two of the problem not studied in the previous work will be presented. These problems are namely the effects of the link elements used at solid-fluid interfaces and of the concentrated loads on the response of the fluid medium. Truss elements are used as the link elements. After these investigations, it is decided that general purpose finite element programs with slight modifications can be used in the safety analysis of nuclear reactor plants. By this procedure it is possible to handle two-dimensional plane strain and tridimensional axisymmetric problems of this type. (orig.)
Finite element computational fluid mechanics
Baker, A.J.
1983-01-01
This book analyzes finite element theory as applied to computational fluid mechanics. It includes a chapter on using the heat conduction equation to expose the essence of finite element theory, including higher-order accuracy and convergence in a common knowledge framework. Another chapter generalizes the algorithm to extend application to the nonlinearity of the Navier-Stokes equations. Other chapters are concerned with the analysis of a specific fluids mechanics problem class, including theory and applications. Some of the topics covered include finite element theory for linear mechanics; potential flow; weighted residuals/galerkin finite element theory; inviscid and convection dominated flows; boundary layers; parabolic three-dimensional flows; and viscous and rotational flows
Abbott, T.I.; Jones, C.G.
1984-01-01
Radiographic elements are disclosed comprised of first and second silver halide emulsion layers separated by an interposed support capable of transmitting radiation to which the second image portion is responsive. At least the first imaging portion contains a silver halide emulsion in which thin tubular silver halide grains of intermediate aspect ratios (from 5:1 to 8:1) are present. Spectral sensitizing dye is adsorbed to the surface of the tubular grains. Increased photographic speeds can be realized at comparable levels of crossover. (author)
Hofmann, S
1999-01-01
The outstanding aim of experimental investigations of heavy nuclei is the exploration of spherical 'SuperHeavy Elements' (SHEs). On the basis of the nuclear shell model, the next double magic shell-closure beyond sup 2 sup 0 sup 8 Pb is predicted at proton numbers between Z=114 and 126 and at neutron number N=184. All experimental efforts aiming at identifying SHEs (Z>=114) were negative so far. A highly sensitive search experiment was performed in November-December 1995 at SHIP. The isotope sup 2 sup 9 sup 0 116 produced by 'radiative capture' was searched for in the course of a 33 days irradiation of a sup 2 sup 0 sup 8 Pb target with sup 8 sup 2 Se projectiles, however, only cross-section limits were measured. Positive results were obtained in experiments searching for elements from 110 to 112 using cold fusion and the 1n evaporation channel. The produced isotopes were unambiguously identified by means of alpha-alpha correlations. Not fission, but alpha emission is the dominant decay mode. The measurement ...
Finite elements methods in mechanics
Eslami, M Reza
2014-01-01
This book covers all basic areas of mechanical engineering, such as fluid mechanics, heat conduction, beams, and elasticity with detailed derivations for the mass, stiffness, and force matrices. It is especially designed to give physical feeling to the reader for finite element approximation by the introduction of finite elements to the elevation of elastic membrane. A detailed treatment of computer methods with numerical examples are provided. In the fluid mechanics chapter, the conventional and vorticity transport formulations for viscous incompressible fluid flow with discussion on the method of solution are presented. The variational and Galerkin formulations of the heat conduction, beams, and elasticity problems are also discussed in detail. Three computer codes are provided to solve the elastic membrane problem. One of them solves the Poisson’s equation. The second computer program handles the two dimensional elasticity problems, and the third one presents the three dimensional transient heat conducti...
Sørensen, Jens Nørkær
2016-01-01
Although there exists a large variety of methods for predicting performance and loadings of wind turbines, the only approach used today by wind turbine manufacturers is based on the blade-element/momentum (BEM) theory by Glauert (Aerodynamic theory. Springer, Berlin, pp. 169-360, 1935). A basic...... assumption in the BEM theory is that the flow takes place in independent stream tubes and that the loading is determined from two-dimensional sectional airfoil characteristics....
Hirose, Yasuo.
1982-01-01
Purpose: To increase the plenum space in a fuel element used for a liquid metal cooled reactor. Constitution: A fuel pellet is secured at one end with an end plug and at the other with a coil spring in a tubular container. A mechanism for fixing the coil spring composed of a tubular unit is mounted by friction with the inner surface of the tubular container. Accordingly, the recoiling force of the coil spring can be retained by fixing mechanism with a small volume, and since a large amount of plenum space can be obtained, the internal pressure rise in the cladding tube can be suppressed even if large quantities of fission products are discharged. (Kamimura, M.)
Istvan Szabo
2017-11-01
Full Text Available In this paper, a state of the art automated defect recognition (ADR system is presented that was developed specifically for Non-Destructive Testing (NDT of powder metallurgy (PM parts using three dimensional X-ray Computed Tomography (CT imaging, towards enabling online quality assurance and enhanced integrity confidence. PM parts exhibit typical defects such as microscopic cracks, porosity, and voids, internal to components that without an effective detection system, limit the growth of industrial applications. Compared to typical testing methods (e.g., destructive such as metallography that is based on sampling, cutting, and polishing of parts, CT provides full coverage of defect detection. This paper establishes the importance and advantages of an automated NDT system for the PM industry applications with particular emphasis on image processing procedures for defect recognition. Moreover, the article describes how to establish a reference library based on real 3D X-ray CT images of net-shape parts. The paper follows the development of the ADR system from processing 2D image slices of a measured 3D X-ray image to processing the complete 3D X-ray image as a whole. The introduced technique is successfully integrated into an automated in-line quality control system highly sought by major industry sectors in Oil and Gas, Automotive, and Aerospace.
Tonks, M.R.; Williamson, R.; Masson, R.
2015-01-01
The Finite Element Method (FEM) is a numerical technique for finding approximate solutions to boundary value problems. While FEM is commonly used to solve solid mechanics equations, it can be applied to a large range of BVPs from many different fields. FEM has been used for reactor fuels modelling for many years. It is most often used for fuel performance modelling at the pellet and pin scale, however, it has also been used to investigate properties of the fuel material, such as thermal conductivity and fission gas release. Recently, the United Stated Department Nuclear Energy Advanced Modelling and Simulation Program has begun using FEM as the basis of the MOOSE-BISON-MARMOT Project that is developing a multi-dimensional, multi-physics fuel performance capability that is massively parallel and will use multi-scale material models to provide a truly predictive modelling capability. (authors)
Banda, Srikanth; Cao, Nan; Tse-Dinh, Yuk-Ching
2017-09-15
We report here a distinct mechanism of interaction between topoisomerase I and RNA polymerase in Mycobacterium tuberculosis and Mycobacterium smegmatis that has evolved independently from the previously characterized interaction between bacterial topoisomerase I and RNA polymerase. Bacterial DNA topoisomerase I is responsible for preventing the hyper-negative supercoiling of genomic DNA. The association of topoisomerase I with RNA polymerase during transcription elongation could efficiently relieve transcription-driven negative supercoiling. Our results demonstrate a direct physical interaction between the C-terminal domains of topoisomerase I (TopoI-CTDs) and the β' subunit of RNA polymerase of M. smegmatis in the absence of DNA. The TopoI-CTDs in mycobacteria are evolutionarily unrelated in amino acid sequence and three-dimensional structure to the TopoI-CTD found in the majority of bacterial species outside Actinobacteria, including Escherichia coli. The functional interaction between topoisomerase I and RNA polymerase has evolved independently in mycobacteria and E. coli, with distinctively different structural elements of TopoI-CTD utilized for this protein-protein interaction. Zinc ribbon motifs in E. coli TopoI-CTD are involved in the interaction with RNA polymerase. For M. smegmatis TopoI-CTD, a 27-amino-acid tail that is rich in basic residues at the C-terminal end is responsible for the interaction with RNA polymerase. Overexpression of recombinant TopoI-CTD in M. smegmatis competed with the endogenous topoisomerase I for protein-protein interactions with RNA polymerase. The TopoI-CTD overexpression resulted in decreased survival following treatment with antibiotics and hydrogen peroxide, supporting the importance of the protein-protein interaction between topoisomerase I and RNA polymerase during stress response of mycobacteria. Copyright © 2017 Elsevier Ltd. All rights reserved.
Relativistic quantum chemistry of the superheavy elements. Closed-shell element 114 as a case study
Schwerdtfeger, Peter; Seth, Michael
2002-01-01
The chemistry of superheavy element 114 is reviewed. The ground state of element 114 is closed shell [112]7s 2 7p 1/2 2 and shows a distinct chemical inertness (low reactivity). This inertness makes it rather difficult to study the atom-at-a-time chemistry of 114 in the gas or liquid phase. (author)
Sasaki, Y [Kyushu University, Fukuoka (Japan). Faculty of Engineering
1997-05-27
To enhance the reliability of electromagnetic/magnetotelluric (MT) survey, calculation results of finite-element methods (FEMs) and finite difference methods (FDMs) were compared. Accuracy of individual methods and convergence of repitition solution were examined. As a result of the investigation, it was found that appropriate accuracy can be obtained from the edge FEM and FDM for the example of vertical magnetic dipole, and that the best accuracy can be obtained from the FDM among four methods for the example of MT survey. It was revealed that the ICBCG (incomplete Cholesky bi-conjugate gradient) method is an excellent method as a solution method of simultaneous equations from the viewpoint of accuracy and calculation time. For the joint FEM, solutions of SOR method converged for both the examples. It was concluded that the cause of error is not due to the error of numerical calculation, but due to the consideration without discontinuity of electric field. The conditions of coefficient matrix increased with decreasing the frequency, which resulted in the unstable numerical calculation. It would be required to incorporate the constraint in a certain form. 4 refs., 12 figs.
Element Interactivity and Intrinsic, Extraneous, and Germane Cognitive Load
Sweller, John
2010-01-01
In cognitive load theory, element interactivity has been used as the basic, defining mechanism of intrinsic cognitive load for many years. In this article, it is suggested that element interactivity underlies extraneous cognitive load as well. By defining extraneous cognitive load in terms of element interactivity, a distinct relation between…
Discrete elements method of neutron transport
Mathews, K.A.
1988-01-01
In this paper a new neutron transport method, called discrete elements (L N ) is derived and compared to discrete ordinates methods, theoretically and by numerical experimentation. The discrete elements method is based on discretizing the Boltzmann equation over a set of elements of angle. The discrete elements method is shown to be more cost-effective than discrete ordinates, in terms of accuracy versus execution time and storage, for the cases tested. In a two-dimensional test case, a vacuum duct in a shield, the L N method is more consistently convergent toward a Monte Carlo benchmark solution
Mueller, P. [Institut Dr. Foerster, Reutlingen, Federal Republic of Germany (Germany)
1965-09-15
continu, des dimensions de parties constitutives metalliques de reacteurs et explique diverses methodes de mesure pour les metaux terreux et non terreux (champs magnetiques des courants continus et des courants alternatifs, courants de Foucault). Il decrit des instruments et donne des exemples de mesure telecommandee du diametre, de l'ovalisation, de la distorsion, etc., de diverses pieces; il expose des methodes de mesure de l'espacement des elements de la zone active du reacteur. Le memoire decrit un instrument permettant d'enregistrer le profil de surface et de faire la lecture directe des valeurs de la rugosite (profondeur de rugosite, degre de polissage, direction des irregularites et valeur quadratique moyenne). Il donne des exemples typiques d'emploi de cet instrument pour les pieces d'un reacteur. L'auteur traite en particulier de la possibilite d'utiliser un petit lecteur polyvalent, a l'aide de manipulateurs, dans les zones actives et pour les matieres 'chaudes'. Il discute l'augmentation de la rugosite de surface en fonction de l'accroissement de l'irradiation. (author) [Spanish] Full text: El autor presenta los problemas de medicion del espesor de hojas y de paredes de tubos y recipientes de material austenftico y no ferroso. Se exponen dos metodos para medir el espesor de paredes sin usar elementos en contacto con las mismas: el metodo de las corrientes de Foucault para medir el espesor de hojas y recipientes de material no ferroso y austenftico, empleando bobinas de transicion, y el empleo de corrientes de Foucault para medir espesores de pared en tubos mediante bobinas anulares extensivas. Se describen los instrumentos adecuados y sus aplicaciones. El autor discute ademas la medicion de espesores de pared en componentes no ferrosos para reactores mediante el 'metodo de la esfera magnetica' y explica el principio de este nuevo procedimiento de medicion, se analiza su alcance, sobre todo para mediciones localizadas, y se describe un instrumento utilizado en
I. L. Alemán Romero
2000-03-01
Full Text Available En este trabajo se muestra la realización computacional en tres dimensiones del Método de los Elementos de Contorno en laTeoría de la Elasticidad Lineal, para medio homogéneo e isotrópico considerando el efecto de las cargas másicas.La realización computacional del método radica en discretizar el contorno mediante elementos en los que losdesplazamientos y las tracciones se suponen variando de acuerdo a funciones de interpolación. Aplicando el “método decolocación” se obtiene un sistema de ecuaciones lineales que aporta la solución en el contorno, a partir de la cual se puedeobtener la solución en cualquier punto de la región de definición del problema.En el presente trabajo se consideran elementos triangulares, se emplea interpolación lineal, se utiliza la transformación acoordenadas homogéneas y se muestran los algoritmos que conducen al ensamblaje del sistema de ecuaciones que aporta lasolución en el contorno.Palabras claves: Elementos de Contorno(MEC, BEM, realización computacional, elementos triangulares.______________________________________________________________________________AbstractIn this work is shown the computational formulation in three dimensions of the Boundary Element Method in 3D Elastostaticfor isotropic, homogeneous and linear material considering the effect of body forces.The computational formulation of the method is based on the discretization of the boundary into elements over whichdisplacements and tractions are expressed in terms of interpolation functions. Applying the collocation method a system oflineal equations is obtained that brings the solution on the boundary, from which the solution in any point of the definitionregion of the problem can be obtained.In the present work triangular elements are considered, lineal interpolation is employed, the transformation to homogenealcoordinates is used and it is shown the algorithms that guide to the assembling of the equations system that
The influence of context on distinct facial expressions of disgust.
Reschke, Peter J; Walle, Eric A; Knothe, Jennifer M; Lopez, Lukas D
2018-06-11
Face perception is susceptible to contextual influence and perceived physical similarities between emotion cues. However, studies often use structurally homogeneous facial expressions, making it difficult to explore how within-emotion variability in facial configuration affects emotion perception. This study examined the influence of context on the emotional perception of categorically identical, yet physically distinct, facial expressions of disgust. Participants categorized two perceptually distinct disgust facial expressions, "closed" (i.e., scrunched nose, closed mouth) and "open" (i.e., scrunched nose, open mouth, protruding tongue), that were embedded in contexts comprising emotion postures and scenes. Results demonstrated that the effect of nonfacial elements was significantly stronger for "open" disgust facial expressions than "closed" disgust facial expressions. These findings provide support that physical similarity within discrete categories of facial expressions is mutable and plays an important role in affective face perception. (PsycINFO Database Record (c) 2018 APA, all rights reserved).
Orlita, M., E-mail: milan.orlita@lncmi.cnrs.fr [Laboratoire National des Champs Magnétiques Intenses, CNRS-UJF-UPS-INSA, 38042 Grenoble (France); Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, 121 16 Prague 2 (Czech Republic); Faugeras, C.; Barra, A.-L.; Martinez, G.; Potemski, M. [Laboratoire National des Champs Magnétiques Intenses, CNRS-UJF-UPS-INSA, 38042 Grenoble (France); Basko, D. M. [LPMMC UMR 5493, Université Grenoble 1/CNRS, B.P. 166, 38042 Grenoble (France); Zholudev, M. S. [Laboratoire Charles Coulomb (L2C), UMR CNRS 5221, GIS-TERALAB, Université Montpellier II, 34095 Montpellier (France); Institute for Physics of Microstructures, RAS, Nizhny Novgorod GSP-105 603950 (Russian Federation); Teppe, F.; Knap, W. [Laboratoire Charles Coulomb (L2C), UMR CNRS 5221, GIS-TERALAB, Université Montpellier II, 34095 Montpellier (France); Gavrilenko, V. I. [Institute for Physics of Microstructures, RAS, Nizhny Novgorod GSP-105 603950 (Russian Federation); Mikhailov, N. N.; Dvoretskii, S. A. [A.V. Rzhanov Institute of Semiconductor Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk 630090 (Russian Federation); Neugebauer, P. [Institut für Physikalische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart (Germany); Berger, C. [School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Institut Néel/CNRS-UJF BP 166, F-38042 Grenoble Cedex 9 (France); Heer, W. A. de [School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)
2015-03-21
Here, we report on a magneto-optical study of two distinct systems hosting massless fermions—two-dimensional graphene and three-dimensional HgCdTe tuned to the zero band gap condition at the point of the semiconductor-to-semimetal topological transition. Both materials exhibit, in the quantum regime, a fairly rich magneto-optical response, which is composed from a series of intra- and interband inter-Landau level resonances with for massless fermions typical √(B) dependence. The impact of the system's dimensionality and of the strength of the spin-orbit interaction on the optical response is also discussed.
Number of perceptually distinct surface colors in natural scenes.
Marín-Franch, Iván; Foster, David H
2010-09-30
The ability to perceptually identify distinct surfaces in natural scenes by virtue of their color depends not only on the relative frequency of surface colors but also on the probabilistic nature of observer judgments. Previous methods of estimating the number of discriminable surface colors, whether based on theoretical color gamuts or recorded from real scenes, have taken a deterministic approach. Thus, a three-dimensional representation of the gamut of colors is divided into elementary cells or points which are spaced at one discrimination-threshold unit intervals and which are then counted. In this study, information-theoretic methods were used to take into account both differing surface-color frequencies and observer response uncertainty. Spectral radiances were calculated from 50 hyperspectral images of natural scenes and were represented in a perceptually almost uniform color space. The average number of perceptually distinct surface colors was estimated as 7.3 × 10(3), much smaller than that based on counting methods. This number is also much smaller than the number of distinct points in a scene that are, in principle, available for reliable identification under illuminant changes, suggesting that color constancy, or the lack of it, does not generally determine the limit on the use of color for surface identification.
Metal transport across biomembranes: emerging models for a distinct chemistry.
Argüello, José M; Raimunda, Daniel; González-Guerrero, Manuel
2012-04-20
Transition metals are essential components of important biomolecules, and their homeostasis is central to many life processes. Transmembrane transporters are key elements controlling the distribution of metals in various compartments. However, due to their chemical properties, transition elements require transporters with different structural-functional characteristics from those of alkali and alkali earth ions. Emerging structural information and functional studies have revealed distinctive features of metal transport. Among these are the relevance of multifaceted events involving metal transfer among participating proteins, the importance of coordination geometry at transmembrane transport sites, and the presence of the largely irreversible steps associated with vectorial transport. Here, we discuss how these characteristics shape novel transition metal ion transport models.
Social conformity despite individual preferences for distinctiveness.
Smaldino, Paul E; Epstein, Joshua M
2015-03-01
We demonstrate that individual behaviours directed at the attainment of distinctiveness can in fact produce complete social conformity. We thus offer an unexpected generative mechanism for this central social phenomenon. Specifically, we establish that agents who have fixed needs to be distinct and adapt their positions to achieve distinctiveness goals, can nevertheless self-organize to a limiting state of absolute conformity. This seemingly paradoxical result is deduced formally from a small number of natural assumptions and is then explored at length computationally. Interesting departures from this conformity equilibrium are also possible, including divergence in positions. The effect of extremist minorities on these dynamics is discussed. A simple extension is then introduced, which allows the model to generate and maintain social diversity, including multimodal distinctiveness distributions. The paper contributes formal definitions, analytical deductions and counterintuitive findings to the literature on individual distinctiveness and social conformity.
Automated Fuel Element Closure Welding System
Wahlquist, D.R.
1993-01-01
The Automated Fuel Element Closure Welding System is a robotic device that will load and weld top end plugs onto nuclear fuel elements in a highly radioactive and inert gas environment. The system was developed at Argonne National Laboratory-West as part of the Fuel Cycle Demonstration. The welding system performs four main functions, it (1) injects a small amount of a xenon/krypton gas mixture into specific fuel elements, and (2) loads tiny end plugs into the tops of fuel element jackets, and (3) welds the end plugs to the element jackets, and (4) performs a dimensional inspection of the pre- and post-welded fuel elements. The system components are modular to facilitate remote replacement of failed parts. The entire system can be operated remotely in manual, semi-automatic, or fully automatic modes using a computer control system. The welding system is currently undergoing software testing and functional checkout
Anomaly-specified virtual dimensionality
Chen, Shih-Yu; Paylor, Drew; Chang, Chein-I.
2013-09-01
Virtual dimensionality (VD) has received considerable interest where VD is used to estimate the number of spectral distinct signatures, denoted by p. Unfortunately, no specific definition is provided by VD for what a spectrally distinct signature is. As a result, various types of spectral distinct signatures determine different values of VD. There is no one value-fit-all for VD. In order to address this issue this paper presents a new concept, referred to as anomaly-specified VD (AS-VD) which determines the number of anomalies of interest present in the data. Specifically, two types of anomaly detection algorithms are of particular interest, sample covariance matrix K-based anomaly detector developed by Reed and Yu, referred to as K-RXD and sample correlation matrix R-based RXD, referred to as R-RXD. Since K-RXD is only determined by 2nd order statistics compared to R-RXD which is specified by statistics of the first two orders including sample mean as the first order statistics, the values determined by K-RXD and R-RXD will be different. Experiments are conducted in comparison with widely used eigen-based approaches.
Elemental analysis techniques using proton microbeam
Sakai, Takuro; Oikawa, Masakazu; Sato, Takahiro
2005-01-01
Proton microbeam is a powerful tool for two-dimensional elemental analysis. The analysis is based on Particle Induced X-ray Emission (PIXE) and Particle Induced Gamma-ray Emission (PIGE) techniques. The paper outlines the principles and instruments, and describes the dental application has been done in JAERI Takasaki. (author)
Electrical machine analysis using finite elements
Bianchi, Nicola
2005-01-01
OUTLINE OF ELECTROMAGNETIC FIELDSVector AnalysisElectromagnetic FieldsFundamental Equations SummaryReferencesBASIC PRINCIPLES OF FINITE ELEMENT METHODSIntroductionField Problems with Boundary ConditionsClassical Method for the Field Problem SolutionThe Classical Residual Method (Galerkin's Method)The Classical Variational Method (Rayleigh-Ritz's Method)The Finite Element MethodReferencesAPPLICATIONS OF THE FINITE ELEMENT METHOD TO TWO-DIMENSIONAL FIELDSIntroductionLinear Interpolation of the Function fApplication of the Variational MethodSimple Descriptions of Electromagnetic FieldsAppendix: I
Nondestructive examination techniques on Candu fuel elements
Gheorghe, G.; Man, I.
2013-01-01
During irradiation in nuclear reactor, fuel elements undergo dimensional and structural changes, and changes of surface conditions sheath as well, which can lead to damages and even loss of integrity. Visual examination and photography of Candu fuel elements are among the non-destructive examination techniques, next to dimensional measurements that include profiling (diameter, bending, camber) and length, sheath integrity control with eddy currents, measurement of the oxide layer thickness by eddy current techniques. Unirradiated Zircaloy-4 tubes were used for calibration purposes, whereas irradiated Zircaloy-4 tubes were actually subjected to visual inspection and dimensional measurements. We present results of measurements done by eddy current techniques on Zircaloy- 4 tubes, unirradiated, but oxidized in an autoclave prior to examinations. The purpose of these nondestructive examination techniques is to determine those parameters that characterize the behavior and performance of nuclear fuel operation. (authors)
Validity of Sensory Systems as Distinct Constructs
Su, Chia-Ting; Parham, L. Diane
2014-01-01
Confirmatory factor analysis testing whether sensory questionnaire items represented distinct sensory system constructs found, using data from two age groups, that such constructs can be measured validly using questionnaire data.
Visual distinctiveness can enhance recency effects.
Bornstein, B H; Neely, C B; LeCompte, D C
1995-05-01
Experimental efforts to meliorate the modality effect have included attempts to make the visual stimulus more distinctive. McDowd and Madigan (1991) failed to find an enhanced recency effect in serial recall when the last item was made more distinct in terms of its color. In an attempt to extend this finding, three experiments were conducted in which visual distinctiveness was manipulated in a different manner, by combining the dimensions of physical size and coloration (i.e., whether the stimuli were solid or outlined in relief). Contrary to previous findings, recency was enhanced when the size and coloration of the last item differed from the other items in the list, regardless of whether the "distinctive" item was larger or smaller than the remaining items. The findings are considered in light of other research that has failed to obtain a similar enhanced recency effect, and their implications for current theories of the modality effect are discussed.
New method for solving three-dimensional Schroedinger equation
Melezhik, V.S.
1990-01-01
The method derived recently for solving a multidimensional scattering problem is applied to a three-dimensional Schroedinger equation. As compared with direct three-dimensional calculations of finite elements and finite differences, this approach gives sufficiently accurate upper and lower approximations to the helium-atom binding energy, which demonstrates its efficiency. 15 refs.; 1 fig.; 2 tabs
TRIGA fuel element burnup determination by measurement and calculation
Zagar, T.; Ravnik, M.; Persic, A.; Jeraj, R.
2000-01-01
To estimate the accuracy of the fuel element burnup calculation different factors influencing the calculation were studied. To cover different aspects of burnup calculations, two in-house developed computer codes were used in calculations. The first (TRIGAP) is based on a one-dimensional two-group diffusion approximation, and the second (TRIGLAV) is based on a two-dimensional four-group diffusion equation. Both codes use WIMSD program with different libraries forunit-cell cross section data calculation. The burnup accumulated during the operating history of the TRIGA reactor at Josef Stefan Institute was calculated for all fuel elements. Elements used in the core during this period were standard SS 8.5% fuel elements, standard SS 12% fuel elements and highly enriched FLIP fuel elements. During the considerable period of operational history, FLIP and standard fuel elements were used simultaneously in mixed cores. (authors)
Finite elements for partial differential equations: An introductory survey
Succi, S.
1988-03-01
After presentation of the basic ideas behind the theory of the Finite Element Method, the application of the method to three equations of particular interest in Physics and Engineering is discussed in some detail, namely, a one-dimensional Sturm-Liouville problem, a two-dimensional linear Fokker-Planck equation and a two-dimensional nonlinear Navier-Stokes equation. 6 refs, 8 figs
Efficient Finite Element Models for Calculation of the No-load losses of the Transformer
Kamran Dawood
2017-10-01
Full Text Available Different transformer models are examined for the calculation of the no-load losses using finite element analysis. Two-dimensional and three-dimensional finite element analyses are used for the simulation of the transformer. Results of the finite element method are also compared with the experimental results. The Result shows that 3-dimensional provide high accuracy as compared to the 2 dimensional full and half model. However, the 2-dimensional half model is the less time-consuming method as compared to the 3 and 2-dimensional full model. Simulation time duration taken by the different models of the transformer is also compared. The difference between the 3-dimensional finite element method and experimental results are less than 3%. These numerical methods can help transformer designers to minimize the development of the prototype transformers.
Finite element model to study two dimensional unsteady state ...
Kunal Pathak
2015-10-20
Oct 20, 2015 ... free Ca2+, endogenous Ca2+ binding proteins and other. ''Ca2+ buffers” ... in the literature for the study of calcium dynamics in myocytes.1,2,20,21 ... Since Ca2+ has a molecular weight that is small in compar- ison with most ...
Two dimensional finite element heat transfer models for softwood
Hongmei Gu; John F. Hunt
2004-01-01
The anisotropy of wood creates a complex problem for solving heat and mass transfer problems that require analyses be based on fundamental material properties of the wood structure. Most heat transfer models use average thermal properties across either the radial or tangential directions and have not differentiated the effects of cellular alignment, earlywood/latewood...
Canio Hoffarth
2017-03-01
Full Text Available A three-dimensional constitutive model has been developed for modeling orthotropic composites subject to impact loads. It has three distinct components—a deformation model involving elastic and plastic deformations; a damage model; and a failure model. The model is driven by tabular data that is generated either using laboratory tests or via virtual testing. A unidirectional composite—T800/F3900, commonly used in the aerospace industry, is used in the verification and validation tests. While the failure model is under development, these tests indicate that the implementation of the deformation and damage models in a commercial finite element program, LS-DYNA, is efficient, robust and accurate.
Discrete elements method of neutral particle transport
Mathews, K.A.
1983-01-01
A new discrete elements (L/sub N/) transport method is derived and compared to the discrete ordinates S/sub N/ method, theoretically and by numerical experimentation. The discrete elements method is more accurate than discrete ordinates and strongly ameliorates ray effects for the practical problems studied. The discrete elements method is shown to be more cost effective, in terms of execution time with comparable storage to attain the same accuracy, for a one-dimensional test case using linear characteristic spatial quadrature. In a two-dimensional test case, a vacuum duct in a shield, L/sub N/ is more consistently convergent toward a Monte Carlo benchmark solution than S/sub N/, using step characteristic spatial quadrature. An analysis of the interaction of angular and spatial quadrature in xy-geometry indicates the desirability of using linear characteristic spatial quadrature with the L/sub N/ method
ZONE: a finite element mesh generator
Burger, M.J.
1976-05-01
The ZONE computer program is a finite-element mesh generator which produces the nodes and element description of any two-dimensional geometry. The geometry is subdivided into a mesh of quadrilateral and triangular zones arranged sequentially in an ordered march through the geometry. The order of march can be chosen so that the minimum bandwidth is obtained. The node points are defined in terms of the x and y coordinates in a global rectangular coordinate system. The zones generated are quadrilaterals or triangles defined by four node points in a counterclockwise sequence. Node points defining the outside boundary are generated to describe pressure boundary conditions. The mesh that is generated can be used as input to any two-dimensional as well as any axisymmetrical structure program. The output from ZONE is essentially the input file to NAOS, HONDO, and other axisymmetric finite element programs. 14 figures
Three dimensional visualization of medical images
Suto, Yasuzo
1992-01-01
Three dimensional visualization is a stereoscopic technique that allows the diagnosis and treatment of complicated anatomy site of the bone and organ. In this article, the current status and technical application of three dimensional visualization are introduced with special reference to X-ray CT and MRI. The surface display technique is the most common for three dimensional visualization, consisting of geometric model, voxel element, and stereographic composition techniques. Recent attention has been paid to display method of the content of the subject called as volume rendering, whereby information on the living body is provided accurately. The application of three dimensional visualization is described in terms of diagnostic imaging and surgical simulation. (N.K.)
Anon.
1991-01-01
This chapter addresses the extension of previous work in one-dimensional (linear) error theory to two-dimensional error analysis. The topics of the chapter include the definition of two-dimensional error, the probability ellipse, the probability circle, elliptical (circular) error evaluation, the application to position accuracy, and the use of control systems (points) in measurements
Three dimensional illustrating - three-dimensional vision and deception of sensibility
Anita Gánóczy
2009-03-01
Full Text Available 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 of movement parallax, which can be used efficiently in making three-dimensional graphics, the Zöllner- and Corridor-illusion. There are present in this paper the visual elements, which contribute to define a plane two-dimensional image in three-dimension: coherent lines, the covering, the measurement changes, the relative altitude state, the abatement of detail profusion, the shadings and the perspective effects of colors.
Dimensional cosmological principles
Chi, L.K.
1985-01-01
The dimensional cosmological principles proposed by Wesson require that the density, pressure, and mass of cosmological models be functions of the dimensionless variables which are themselves combinations of the gravitational constant, the speed of light, and the spacetime coordinates. The space coordinate is not the comoving coordinate. In this paper, the dimensional cosmological principle and the dimensional perfect cosmological principle are reformulated by using the comoving coordinate. The dimensional perfect cosmological principle is further modified to allow the possibility that mass creation may occur. Self-similar spacetimes are found to be models obeying the new dimensional cosmological principle
Distinctiveness of Saudi Arabian EFL Learners
Manssour Habbash
2016-04-01
Full Text Available In view of the increasing concern among English language teachers dealing with students from Saudi Arabia, as it manifests in TESOL community discussions, about the uniqueness of Saudi Arabian EFL learners, this paper attempts to document the outcome of a study of their distinctiveness from the perspective of expatriate teachers working for PYPs (Preparatory Year Programs in Saudi Arabia. This study examines the distinctiveness with regard to the learning attitudes of Saudi students that are often cultivated by the culture and academic environment in their homeland. Employing an emic approach for collecting the required data an analysis was carried out in light of the other studies on ‘education’ in Saudi Arabia that have particular reference to the factors that can positively influence student motivation, student success and the academic environment. The findings were used in constructing the rationale behind such distinctiveness. Assuming that the outcome of the discussion on the findings of this exploration can be helpful for teachers in adapting their teaching methodology and improving their teacher efficacy in dealing with students both from the kingdom and in the kingdom, some recommendations are made. Keywords: China Distinctiveness, Saudi Arabian University context, Expatriate teachers’ perspective, Distinctiveness Theory
Super integrable four-dimensional autonomous mappings
Capel, H W; Sahadevan, R; Rajakumar, S
2007-01-01
A systematic investigation of the complete integrability of a fourth-order autonomous difference equation of the type w(n + 4) = w(n)F(w(n + 1), w(n + 2), w(n + 3)) is presented. We identify seven distinct families of four-dimensional mappings which are super integrable and have three (independent) integrals via a duality relation as introduced in a recent paper by Quispel, Capel and Roberts (2005 J. Phys. A: Math. Gen. 38 3965-80). It is observed that these seven families can be related to the four-dimensional symplectic mappings with two integrals including all the four-dimensional periodic reductions of the integrable double-discrete modified Korteweg-deVries and sine-Gordon equations treated in an earlier paper by two of us (Capel and Sahadevan 2001 Physica A 289 86-106)
Finite element modeling of piezoelectric elements with complex electrode configuration
Paradies, R; Schläpfer, B
2009-01-01
realized for a commercial finite element program allowing for an automatic assignment of different material properties for two- and three-dimensional FEMs with arbitrary electrode configurations. Examples of piezoelectric transducers with complex electrode configurations are presented and the influence of the material description on the behavior of the modeled element is discussed. Furthermore, as an attempt at verification of the FEM simulation, a comparison of simulated stress concentrations with experimental investigations is presented
On Hobbes’s distinction of accidents
Lupoli Agostino
2012-06-01
Full Text Available An interpolation introduced by K. Schuhmann in his critical edition of "De corpore" (chap. VI, § 13 diametrically overturns the meaning of Hobbes’s doctrine of distinction of accidents in comparison with all previous editions. The article focuses on the complexity of this crucial juncture in "De corpore" argument on which depends the interpretation of Hobbes’s whole conception of science. It discusses the reasons pro and contra Schuhmann’s interpolation and concludes against it, because it is not compatible with the rationale underlying the complex architecture of "De corpore", which involves a symmetry between the ‘logical’ distinction of accidents and the ‘metaphysical’ distinction of phantasms.
What makes health promotion research distinct?
Woodall, James; Warwick-Booth, Louise; South, Jane; Cross, Ruth
2018-02-01
There have been concerns about the decline of health promotion as a practice and discipline and, alongside this, calls for a clearer articulation of health promotion research and what, if anything, makes it distinct. This discussion paper, based on a review of the literature, the authors' own experiences in the field, and a workshop delivered by two of the authors at the 8th Nordic Health Promotion Conference, seeks to state the reasons why health promotion research is distinctive. While by no means exhaustive, the paper suggests four distinctive features. The paper hopes to be a catalyst to enable health promotion researchers to be explicit in their practice and to begin the process of developing an agreed set of research principles.
Intergroup Leadership Across Distinct Subgroups and Identities.
Rast, David E; Hogg, Michael A; van Knippenberg, Daan
2018-03-01
Resolving intergroup conflict is a significant and often arduous leadership challenge, yet existing theory and research rarely, if ever, discuss or examine this situation. Leaders confront a significant challenge when they provide leadership across deep divisions between distinct subgroups defined by self-contained identities-The challenge is to avoid provoking subgroup identity distinctiveness threat. Drawing on intergroup leadership theory, three studies were conducted to test the core hypothesis that, where identity threat exists, leaders promoting an intergroup relational identity will be better evaluated and are more effective than leaders promoting a collective identity; in the absence of threat, leaders promoting a collective identity will prevail. Studies 1 and 2 ( N = 170; N = 120) supported this general proposition. Study 3 ( N = 136) extended these findings, showing that leaders promoting an intergroup relational identity, but not a collective identity, improved intergroup attitudes when participants experienced an identity distinctiveness threat.
Distinctive Dynamic Capabilities for New Business Creation
Rosenø, Axel; Enkel, Ellen; Mezger, Florian
2013-01-01
This study examines the distinctive dynamic capabilities for new business creation in established companies. We argue that these are very different from those for managing incremental innovation within a company's core business. We also propose that such capabilities are needed in both slow...... and fast-paced industries, and that similarities exist across industries. Hence, the study contributes to dynamic capabilities literature by: 1) identifying the distinctive dynamic capabilities for new business creation; 2) shifting focus away from dynamic capabilities in environments characterised by high...... clock-speed and uncertainty towards considering dynamic capabilities for the purpose of developing new businesses, which also implies a high degree of uncertainty. Based on interviews with 33 companies, we identify distinctive dynamic capabilities for new business creation, find that dynamic...
INGEN: a general-purpose mesh generator for finite element codes
Cook, W.A.
1979-05-01
INGEN is a general-purpose mesh generator for two- and three-dimensional finite element codes. The basic parts of the code are surface and three-dimensional region generators that use linear-blending interpolation formulas. These generators are based on an i, j, k index scheme that is used to number nodal points, construct elements, and develop displacement and traction boundary conditions. This code can generate truss elements (2 modal points); plane stress, plane strain, and axisymmetry two-dimensional continuum elements (4 to 8 nodal points); plate elements (4 to 8 nodal points); and three-dimensional continuum elements (8 to 21 nodal points). The traction loads generated are consistent with the element generated. The expansion--contraction option is of special interest. This option makes it possible to change an existing mesh such that some regions are refined and others are made coarser than the original mesh. 9 figures
Three dimensional analysis of laterally loaded piles
Yilmaz, C.
1987-01-01
In this study static analysis of laterally loaded pile is studied by the three models. The first model is the beam on discrete elastic springs. This model is analyzed using a flexibility method. The second model is the beam on a two-parameter elastic foundation. This model is analyzed using the linear finite element method. The third model is the finite element model, using the three-dimensional iso-parametric parabolic brick element. Three-dimensional pile group analysis is also performed using elastic constants of single pile obtained by any one of the above analyses. The main objective is to develop computer programs for each model related to single piles and to group analysis. Then, the deflections, rotations, moments, shears, stresses and strains of the single pile are obtained at any arbitrary point. Comparison is made between each model and with other studies such as Poulos 1971, Desai and Appel 1976. In addition, to provide a benchmark of three-dimensional finite element analysis, the Boussinesq problem is analyzed. (orig.)
Greenwood, N.N.; Earnshaw, A.
1984-01-01
This textbook presents an account of the chemistry of the elements for both undergraduate and postgraduate students. It covers not only the 'inorganic' chemistry of the elements, but also analytical, theoretical, industrial, organometallic;, bio-inorganic and other areas of chemistry which apply. The following elements of special nuclear interest are included: Rb, Cs, Fr, Sr, Ba, Ra, Po, At, Rn, Sc, Y, Zr, Hf, V, Nb, Ta, Mo, Tc, Ru, the Lanthanide Elements, the Actinide Elements. (U.K.)
Predoi, Mihai Valentin
2014-09-01
The dispersion curves for hollow multilayered cylinders are prerequisites in any practical guided waves application on such structures. The equations for homogeneous isotropic materials have been established more than 120 years ago. The difficulties in finding numerical solutions to analytic expressions remain considerable, especially if the materials are orthotropic visco-elastic as in the composites used for pipes in the last decades. Among other numerical techniques, the semi-analytical finite elements method has proven its capability of solving this problem. Two possibilities exist to model a finite elements eigenvalue problem: a two-dimensional cross-section model of the pipe or a radial segment model, intersecting the layers between the inner and the outer radius of the pipe. The last possibility is here adopted and distinct differential problems are deduced for longitudinal L(0,n), torsional T(0,n) and flexural F(m,n) modes. Eigenvalue problems are deduced for the three modes classes, offering explicit forms of each coefficient for the matrices used in an available general purpose finite elements code. Comparisons with existing solutions for pipes filled with non-linear viscoelastic fluid or visco-elastic coatings as well as for a fully orthotropic hollow cylinder are all proving the reliability and ease of use of this method. Copyright © 2014 Elsevier B.V. All rights reserved.
Determination of the burn-up of TRIGA fuel elements by calculation with new TRIGLAV program
Zagar, T.; Ravnik, M.
1996-01-01
The results of fuel element burn-up calculations with new TRIGLAV program are presented. TRIGLAV program uses two dimensional model. Results of calculation are compared to results calculated with program, which uses one dimensional model. The results of fuel element burn-up measurements with reactivity method are presented and compared with the calculated results. (author)
Densis. Densimetric representation of two-dimensional matrices
Los Arcos Merino, J.M.
1978-01-01
Densis is a Fortran V program which allows off-line control of a Calcomp digital plotter, to represent a two-dimensional matrix of numerical elements in the form of a variable shading intensity map in two colours. Each matrix element is associated to a square of a grid which is traced over by lines whose number is a function of the element value according to a selected scale. Program features, subroutine structure and running instructions, are described. Some typical results, for gamma-gamma coincidence experimental data and a sampled two-dimensional function, are indicated. (author)
Low-dimensional geometry from euclidean surfaces to hyperbolic knots
Bonahon, Francis
2009-01-01
The study of 3-dimensional spaces brings together elements from several areas of mathematics. The most notable are topology and geometry, but elements of number theory and analysis also make appearances. In the past 30 years, there have been striking developments in the mathematics of 3-dimensional manifolds. This book aims to introduce undergraduate students to some of these important developments. Low-Dimensional Geometry starts at a relatively elementary level, and its early chapters can be used as a brief introduction to hyperbolic geometry. However, the ultimate goal is to describe the very recently completed geometrization program for 3-dimensional manifolds. The journey to reach this goal emphasizes examples and concrete constructions as an introduction to more general statements. This includes the tessellations associated to the process of gluing together the sides of a polygon. Bending some of these tessellations provides a natural introduction to 3-dimensional hyperbolic geometry and to the theory o...
Three dimensional periodic foundations for base seismic isolation
Yan, Y; Mo, Y L; Cheng, Z; Shi, Z; Menq, F; Tang, Y
2015-01-01
Based on the concept of phononic crystals, periodic foundations made of periodic materials are investigated in this paper. The periodic foundations can provide low frequency band gaps, which cover the main frequency ranges of seismic waves. Therefore, the periodic foundations are able to protect the upper structures during earthquake events. In this paper, the basic theory of three dimensional periodic foundations is studied and the finite element method was used to conduct the sensitivity study. A simplified three-dimensional periodic foundation with a superstructure was tested in the field and the feasibility of three dimensional periodic foundations was proved. The test results showed that the response of the upper structure with the three dimensional periodic foundation was reduced under excitation waves with the main frequency falling in the attenuation zones. The finite element analysis results are consistent with the experimental data, indicating that three dimensional periodic foundations are a feasible way of reducing seismic vibrations. (paper)
Noncoding Elements: Evolution and Epigenetic Regulation
Seridi, Loqmane
2016-03-09
When the human genome project was completed, it revealed a surprising result. 98% of the genome did not code for protein of which more than 50% are repeats— later known as ”Junk DNA”. However, comparative genomics unveiled that many noncoding elements are evolutionarily constrained; thus luckily to have a role in genome stability and regulation. Though, their exact functions remained largely unknown. Several large international consortia such as the Functional Annotation of Mammalian Genomes (FANTOM) and the Encyclopedia of DNA Elements (ENCODE) were set to understand the structure and the regulation of the genome. Specifically, these endeavors aim to measure and reveal the transcribed components and functional elements of the genome. One of the most the striking findings of these efforts is that most of the genome is transcribed, including non-conserved noncoding elements and repeat elements. Specifically, we investigated the evolution and epigenetic properties of noncoding elements. 1. We compared genomes of evolutionarily distant species and showed the ubiquity of constrained noncoding elements in metazoa. 2. By integrating multi-omic data (such as transcriptome, nucleosome profiling, histone modifications), I conducted a comprehensive analysis of epigenetic properties (chromatin states) of conserved noncoding elements in insects. We showed that those elements have distinct and protective sequence features, undergo dynamic epigenetic regulation, and appear to be associated with the structural components of the chromatin, replication origins, and nuclear matrix. 3. I focused on the relationship between enhancers and repetitive elements. Using Cap Analysis of Gene Expression (CAGE) and RNASeq, I compiled a full catalog of active enhancers (a class of noncoding elements) during myogenesis of human primary cells of healthy donors and donors affected by Duchenne muscular dystrophy (DMD). Comparing the two time-courses, a significant change in the epigenetic
Dimensional reduction of a generalized flux problem
Moroz, A.
1992-01-01
In this paper, a generalized flux problem with Abelian and non-Abelian fluxes is considered. In the Abelian case we shall show that the generalized flux problem for tight-binding models of noninteracting electrons on either 2n- or (2n + 1)-dimensional lattice can always be reduced to an n-dimensional hopping problem. A residual freedom in this reduction enables one to identify equivalence classes of hopping Hamiltonians which have the same spectrum. In the non-Abelian case, the reduction is not possible in general unless the flux tensor factorizes into an Abelian one times are element of the corresponding algebra
Autocorrelation based reconstruction of two-dimensional binary objects
Mejia-Barbosa, Y.; Castaneda, R.
2005-10-01
A method for reconstructing two-dimensional binary objects from its autocorrelation function is discussed. The objects consist of a finite set of identical elements. The reconstruction algorithm is based on the concept of class of element pairs, defined as the set of element pairs with the same separation vector. This concept allows to solve the redundancy introduced by the element pairs of each class. It is also shown that different objects, consisting of an equal number of elements and the same classes of pairs, provide Fraunhofer diffraction patterns with identical intensity distributions. However, the method predicts all the possible objects that produce the same Fraunhofer pattern. (author)
Common and distinct components in data fusion
Smilde, Age Klaas; Mage, Ingrid; Næs, Tormod
2016-01-01
and understanding their relative merits. This paper provides a unifying framework for this subfield of data fusion by using rigorous arguments from linear algebra. The most frequently used methods for distinguishing common and distinct components are explained in this framework and some practical examples are given...
Knowledge Affords Distinctive Processing in Memory
Hunt, R. Reed; Rawson, Katherine A.
2011-01-01
The effect of knowledge on memory generally is processing. However, both conceptual and empirical reasons exist to suspect that the organizational account is incomplete. Recently a revised version of that account has been proposed under the rubric of distinctiveness theory (Rawson & Van Overschelde, 2008). The goal of the experiments reported…
Distinctiveness of Saudi Arabian EFL Learners
Habbash, Manssour; Idapalapati, Srinivasa Rao
2016-01-01
In view of the increasing concern among English language teachers dealing with students from Saudi Arabia, as it manifests in TESOL community discussions, about the uniqueness of Saudi Arabian EFL learners, this paper attempts to document the outcome of a study of their distinctiveness from the perspective of expatriate teachers working for PYPs…
Numerical and spectral investigations of novel infinite elements
Barai, P.; Harari, I.; Barbonet, P.E.
1998-01-01
Exterior problems of time-harmonic acoustics are addressed by a novel infinite element formulation, defined on a bounded computational domain. For two-dimensional configurations with circular interfaces, the infinite element results match Quell both analytical values and those obtained from. other methods like DtN. Along 1uith the numerical performance of this formulation, of considerable interest are its complex-valued eigenvalues. Hence, a spectral analysis of the present scheme is also performed here, using various infinite elements
The finite element method its basis and fundamentals
Zienkiewicz, Olek C; Zhu, JZ
2013-01-01
The Finite Element Method: Its Basis and Fundamentals offers a complete introduction to the basis of the finite element method, covering fundamental theory and worked examples in the detail required for readers to apply the knowledge to their own engineering problems and understand more advanced applications. This edition sees a significant rearrangement of the book's content to enable clearer development of the finite element method, with major new chapters and sections added to cover: Weak forms Variational forms Multi-dimensional field prob
National Aeronautics and Space Administration — There is a sustained effort to develop super-lightweight composites by using polymer impregnation of carbon nanotube (CNT) sheets. This promising area is still in...
Finite-element analysis of dynamic fracture
Aberson, J. A.; Anderson, J. M.; King, W. W.
1976-01-01
Applications of the finite element method to the two dimensional elastodynamics of cracked structures are presented. Stress intensity factors are computed for two problems involving stationary cracks. The first serves as a vehicle for discussing lumped-mass and consistent-mass characterizations of inertia. In the second problem, the behavior of a photoelastic dynamic tear test specimen is determined for the time prior to crack propagation. Some results of a finite element simulation of rapid crack propagation in an infinite body are discussed.
Embarrassment: its distinct form and appeasement functions.
Keltner, D; Buswell, B N
1997-11-01
The authors address 2 questions about embarrassment. First, Is embarrassment a distinct emotion? The evidence indicates that the antecedents, experience, and display of embarrassment, and to a limited extent its autonomic physiology, are distinct from shame, guilt, and amusement and share the dynamic, temporal characteristics of emotion. Second, What are the theoretical accounts of embarrassment? Three accounts focus on the causes of embarrassment, positioning that it follows the loss of self-esteem, concern for others' evaluations, or absence of scripts to guide interactions. A fourth account focuses on the effects of the remedial actions of embarrassment, which correct preceding transgressions. A fifth account focuses on the functional parallels between embarrassment and nonhuman appeasement. The discussion focuses on unanswered questions about embarrassment.
Distinctive skeletal dysplasia in Cockayne syndrome
Silengo, M.C.; Franceschini, P.; Bianco, R.; Biagioli, M.; Pastorin, L.; Vista, N.; Baldassar, A.; Benso, L.
1986-01-01
Cockayne syndrom is a well-known autosomal recessive form of dwarfism with senile-like appearance. Skeletal changes such as flattening of vertebral bodies, ivory epiphyses and thickening of cranial vault, have been observed in some patients with this condition. We describe here a 5.5-year-old girl with the typical clinical signs of Cockayne syndrome and a distinctive form of bone dysplasia with major involvment of the spine. (orig.)
Distinctive skeletal dysplasia in Cockayne syndrome
Silengo, M.C.; Franceschini, P.; Bianco, R.; Biagioli, M.; Pastorin, L.; Vista, N.; Baldassar, A.; Benso, L.
1986-03-01
Cockayne syndrome is a well-known autosomal recessive form of dwarfism with senile-like appearance. Skeletal changes such as flattening of vertebral bodies, ivory epiphyses and thickening of cranial vault, have been observed in some patients with this condition. We describe here a 5.5-year-old girl with the typical clinical signs of Cockayne syndrome and a distinctive form of bone dysplasia with major involvement of the spine.
Army nurses in wartime: distinction and pride.
Higgins, L P
1996-08-01
Nurses have served with distinction in wartime since Florence Nightingale went to the Crimea. Women often accompanied their husbands to battle during the Revolutionary and Civil Wars, caring for the sick and wounded. Although not officially given officer status until 1920, Army nurses served in the Spanish-American War and World War I. As officers, thousands of nurses served in subsequent wars, distinguishing themselves by their heroism, devotion to duty, and sheer tenacity of spirit.
Data Element Registry Services
U.S. Environmental Protection Agency — Data Element Registry Services (DERS) is a resource for information about value lists (aka code sets / pick lists), data dictionaries, data elements, and EPA data...
Lee, Byeong Hae
1992-02-01
This book gives descriptions of basic finite element method, which includes basic finite element method and data, black box, writing of data, definition of VECTOR, definition of matrix, matrix and multiplication of matrix, addition of matrix, and unit matrix, conception of hardness matrix like spring power and displacement, governed equation of an elastic body, finite element method, Fortran method and programming such as composition of computer, order of programming and data card and Fortran card, finite element program and application of nonelastic problem.
Brown, J.D.
1988-01-01
This book addresses the subject of gravity theories in two and three spacetime dimensions. The prevailing philosophy is that lower dimensional models of gravity provide a useful arena for developing new ideas and insights, which are applicable to four dimensional gravity. The first chapter consists of a comprehensive introduction to both two and three dimensional gravity, including a discussion of their basic structures. In the second chapter, the asymptotic structure of three dimensional Einstein gravity with a negative cosmological constant is analyzed. The third chapter contains a treatment of the effects of matter sources in classical two dimensional gravity. The fourth chapter gives a complete analysis of particle pair creation by electric and gravitational fields in two dimensions, and the resulting effect on the cosmological constant
Three dimensional strained semiconductors
Voss, Lars; Conway, Adam; Nikolic, Rebecca J.; Leao, Cedric Rocha; Shao, Qinghui
2016-11-08
In one embodiment, an apparatus includes a three dimensional structure comprising a semiconductor material, and at least one thin film in contact with at least one exterior surface of the three dimensional structure for inducing a strain in the structure, the thin film being characterized as providing at least one of: an induced strain of at least 0.05%, and an induced strain in at least 5% of a volume of the three dimensional structure. In another embodiment, a method includes forming a three dimensional structure comprising a semiconductor material, and depositing at least one thin film on at least one surface of the three dimensional structure for inducing a strain in the structure, the thin film being characterized as providing at least one of: an induced strain of at least 0.05%, and an induced strain in at least 5% of a volume of the structure.
Clustering high dimensional data
Assent, Ira
2012-01-01
High-dimensional data, i.e., data described by a large number of attributes, pose specific challenges to clustering. The so-called ‘curse of dimensionality’, coined originally to describe the general increase in complexity of various computational problems as dimensionality increases, is known...... to render traditional clustering algorithms ineffective. The curse of dimensionality, among other effects, means that with increasing number of dimensions, a loss of meaningful differentiation between similar and dissimilar objects is observed. As high-dimensional objects appear almost alike, new approaches...... for clustering are required. Consequently, recent research has focused on developing techniques and clustering algorithms specifically for high-dimensional data. Still, open research issues remain. Clustering is a data mining task devoted to the automatic grouping of data based on mutual similarity. Each cluster...
Radiolabelled cellular blood elements
Sinzinger, H.
1990-01-01
This book reports on radiolabelled cellular blood elements, covering new advances made during the past several years, in particular the use of Tc-99 as a tracer for blood elements. Coverage extends to several radiolabelled monoclonal antibodies that are specific for blood components and may label blood elements in vivo
A non conforming finite element method for computing eigenmodes of resonant cavities
Touze, F.; Le Meur, G.
1990-06-01
We present here a non conforming finite element in R 3 . This finite element, built on tetrahedrons, is particularly suited for computing eigenmodes. The main advantage of this element is that it preserves some structural properties of the space in which the solutions of the Maxwell's equations are to be found. Numerical results are presented for both two-dimensional and three-dimensional cases
Kondo effect in three-dimensional Dirac and Weyl systems
Mitchell, Andrew K.; Fritz, Lars
2015-01-01
Magnetic impurities in three-dimensional Dirac and Weyl systems are shown to exhibit a fascinatingly diverse range of Kondo physics, with distinctive experimental spectroscopic signatures. When the Fermi level is precisely at the Dirac point, Dirac semimetals are in fact unlikely candidates for a
Approximate Approaches to the One-Dimensional Finite Potential Well
Singh, Shilpi; Pathak, Praveen; Singh, Vijay A.
2011-01-01
The one-dimensional finite well is a textbook problem. We propose approximate approaches to obtain the energy levels of the well. The finite well is also encountered in semiconductor heterostructures where the carrier mass inside the well (m[subscript i]) is taken to be distinct from mass outside (m[subscript o]). A relevant parameter is the mass…
Camilo Méndez
2014-12-01
Full Text Available Rare (Earth Elements is a cycle of works for solo piano. The cycle was inspired by James Dillon’s Book of Elements (Vol. I-V. The complete cycle will consist of 14 pieces; one for each selected rare (earth element. The chosen elements are Neodymium, Erbium, Tellurium, Hafnium, Tantalum, Technetium, Indium, Dysprosium, Lanthanium, Cerium, Europium, Terbium, Yttrium and Darmstadtium. These elements were selected due to their special atomic properties that in many cases make them extremely valuable for the development of new technologies, and also because of their scarcity. To date, only 4 works have been completed Yttrium, Technetium, Indium and Tellurium.
Wachspress, E.
2009-01-01
Triangles and rectangles are the ubiquitous elements in finite element studies. Only these elements admit polynomial basis functions. Rational functions provide a basis for elements having any number of straight and curved sides. Numerical complexities initially associated with rational bases precluded extensive use. Recent analysis has reduced these difficulties and programs have been written to illustrate effectiveness. Although incorporation in major finite element software requires considerable effort, there are advantages in some applications which warrant implementation. An outline of the basic theory and of recent innovations is presented here. (authors)
Seaborg, G.T.; Loveland, W.D.
1990-01-01
This book is the 12th volume in a series on transuranium elements. Varied techniques for production of these elements, the methods used in the identification, and the exquisitely refined microchemical techniques required to deal wth samples sometimes involving only a few atoms are described in detail. The chapter on synthesis of the new elements is liberally laced with reminiscences of the proud progenitors as well as the criteria for the discovery of a new chemical element. The authors lament that the superheavy elements (elements in the region of atomic number 114) still elude detection even though their creation should be possible, and some, at least, should survive long enough to be detected. One chapter in the book is devoted to practical applictions of uranium, and the transuranic elements
Dimensional comparison theory.
Möller, Jens; Marsh, Herb W
2013-07-01
Although social comparison (Festinger, 1954) and temporal comparison (Albert, 1977) theories are well established, dimensional comparison is a largely neglected yet influential process in self-evaluation. Dimensional comparison entails a single individual comparing his or her ability in a (target) domain with his or her ability in a standard domain (e.g., "How good am I in math compared with English?"). This article reviews empirical findings from introspective, path-analytic, and experimental studies on dimensional comparisons, categorized into 3 groups according to whether they address the "why," "with what," or "with what effect" question. As the corresponding research shows, dimensional comparisons are made in everyday life situations. They impact on domain-specific self-evaluations of abilities in both domains: Dimensional comparisons reduce self-concept in the worse off domain and increase self-concept in the better off domain. The motivational basis for dimensional comparisons, their integration with recent social cognitive approaches, and the interdependence of dimensional, temporal, and social comparisons are discussed. PsycINFO Database Record (c) 2013 APA, all rights reserved.
Collective transport of Lennard–Jones particles through one-dimensional periodic potentials
He Jian-hui; Wen Jia-le; Chen Pei-rong; Zheng Dong-qin; Zhong Wei-rong
2017-01-01
The surrounding media in which transport occurs contains various kinds of fields, such as particle potentials and external potentials. One of the important questions is how elements work and how position and momentum are redistributed in the diffusion under these conditions. For enriching Fick’s law, ordinary non-equilibrium statistical physics can be used to understand the complex process. This study attempts to discuss particle transport in the one-dimensional channel under external potential fields. Two kinds of potentials—the potential well and barrier—which do not change the potential in total, are built during the diffusion process. There are quite distinct phenomena because of the different one-dimensional periodic potentials. By the combination of a Monte Carlo method and molecular dynamics, we meticulously explore why an external potential field impacts transport by the subsection and statistical method. Besides, one piece of evidence of the Maxwell velocity distribution is confirmed under the assumption of local equilibrium. The simple model is based on the key concept that relates the flux to sectional statistics of position and momentum and could be referenced in similar transport problems. (rapid communication)
A distinction of two discourses concerning wellbeing
Wistoft, Karen; Qvortrup, Lars
2017-01-01
and behavioral mental health interventions, while the latter defines wellbeing in positive terms with a focus on wellbeing as the result of learning and with pedagogical interventions that only indirectly can support the individual’s learning activity. The former sees wellbeing as the result of a “wellbeing cure......The article concerns the current discourses concerning well-being with the point that it is important to make a distinction between a healthcare oriented discourse and a learning oriented discourse. The former defines wellbeing in negative terms and looks at causally oriented aspects of wellbeing......”, while the latter sees wellbeing as the result of wellbeing learning processes....
Approaching the Distinction between Intuition and Insight.
Zhang, Zhonglu; Lei, Yi; Li, Hong
2016-01-01
Intuition and insight share similar cognitive and neural basis. Though, there are still some essential differences between the two. Here in this short review, we discriminated between intuition, and insight in two aspects. First, intuition, and insight are toward different aspects of information processing. Whereas intuition involves judgment about "yes or no," insight is related to "what" is the solution. Second, tacit knowledge play different roles in between intuition and insight. On the one hand, tacit knowledge is conducive to intuitive judgment. On the other hand, tacit knowledge may first impede but later facilitate insight occurrence. Furthermore, we share theoretical, and methodological views on how to access the distinction between intuition and insight.
Three dimensional canonical transformations
Tegmen, A.
2010-01-01
A generic construction of canonical transformations is given in three-dimensional phase spaces on which Nambu bracket is imposed. First, the canonical transformations are defined as based on cannonade transformations. Second, it is shown that determination of the generating functions and the transformation itself for given generating function is possible by solving correspondent Pfaffian differential equations. Generating functions of type are introduced and all of them are listed. Infinitesimal canonical transformations are also discussed as the complementary subject. Finally, it is shown that decomposition of canonical transformations is also possible in three-dimensional phase spaces as in the usual two-dimensional ones.
Strack, O. D. L.
2018-02-01
We present equations for new limitless analytic line elements. These elements possess a virtually unlimited number of degrees of freedom. We apply these new limitless analytic elements to head-specified boundaries and to problems with inhomogeneities in hydraulic conductivity. Applications of these new analytic elements to practical problems involving head-specified boundaries require the solution of a very large number of equations. To make the new elements useful in practice, an efficient iterative scheme is required. We present an improved version of the scheme presented by Bandilla et al. (2007), based on the application of Cauchy integrals. The limitless analytic elements are useful when modeling strings of elements, rivers for example, where local conditions are difficult to model, e.g., when a well is close to a river. The solution of such problems is facilitated by increasing the order of the elements to obtain a good solution. This makes it unnecessary to resort to dividing the element in question into many smaller elements to obtain a satisfactory solution.