Nuclear microscopy of sperm cell elemental structure
Theories suggest there is a link between protamine concentrations in individual sperm and male fertility. Previously, biochemical analyses have used pooled samples containing millions of sperm to determine protamine concentrations. These methods have not been able to determine what percentage of morphologically normal sperm are biochemically defective and potentially infertile. Nuclear microscopy has been utilized to measure elemental profiles at the single sperm level. By measuring the amount of phosphorus and sulfur, the total DNA and protamine content in individual sperm from fertile bull and mouse semen have been determined. These values agree with results obtained from other biochemical analyses. Nuclear microscopy shows promise for measuring elemental profiles in the chromatin of individual sperm. The technique may be able to resolve theories regarding the importance of protamines to male fertility and identify biochemical defects responsible for certain types of male infertility. (orig.)
Structural elements design manual
Draycott, Trevor
2012-01-01
Gives clear explanations of the logical design sequence for structural elements. The Structural Engineer says: `The book explains, in simple terms, and with many examples, Code of Practice methods for sizing structural sections in timber, concrete,masonry and steel. It is the combination into one book of section sizing methods in each of these materials that makes this text so useful....Students will find this an essential support text to the Codes of Practice in their study of element sizing'.
Nakano, Akihiko; Matsumoto, Hitoshi; Uda, Hiroshi; Komatsu, Yasumitsu; Ikegami, Kiyoharu.
1989-05-18
In the existing CdS/CdTe-based solar cell element, nothing is formed except the component effective for generating electromotive force and the components necessary for leading, collecting and extracting the generated electricity, hence even when the element shows deterioration of its performance during its usage, it has been difficult to analyze the above situation. In addition, it has also a defect that its characteristic such as the transfer efficiency in the neighborhood of its glass substrate in connection also with its manufacturing process. In order to solve the above problematical points, this invention proposes, with regard to a CdS-based solar cell element composed by forming a thin film on its substrate, to make a blank space on the above substrate and form thereon a thin film which composes the solar cell element concerned alone or in a piling up manner. 4 figs.
Besenhard, Maximilian O; Jarzabek, Monika; O'Farrell, Alice C; Callanan, John J; Prehn, Jochen Hm; Byrne, Annette T; Huber, Heinrich J
2016-08-01
Computer models allow the mechanistically detailed study of tumour proliferation and its dependency on nutrients. However, the computational study of large vascular tumours requires detailed information on the 3-dimensional vessel network and rather high computation times due to complex geometries. This study puts forward the idea of partitioning vascularised tissue into connected avascular elements that can exchange cells and nutrients between each other. Our method is able to rapidly calculate the evolution of proliferating as well as dead and quiescent cells, and hence a proliferative index, from a given amount and distribution of vascularisation of arbitrary complexity. Applying our model, we found that a heterogeneous vessel distribution provoked a higher proliferative index, suggesting increased malignancy, and increased the amount of dead cells compared to a more static tumour environment when a homogenous vessel distribution was assumed. We subsequently demonstrated that under certain amounts of vascularisation, cell proliferation may even increase when vessel density decreases, followed by a subsequent decrease of proliferation. This effect was due to a trade-off between an increase in compensatory proliferation for replacing dead cells and a decrease of cell population due to lack of oxygen supply in lowly vascularised tumours. Findings were illustrated by an ectopic colorectal cancer mouse xenograft model. Our presented approach can be in the future applied to study the effect of cytostatic, cytotoxic and anti-angiogenic chemotherapy and is ideally suited for translational systems biology, where rapid interaction between theory and experiment is essential. PMID:27155046
Pasquariello, Vito; Hammerl, Georg; Örley, Felix; Hickel, Stefan; Danowski, Caroline; Popp, Alexander; Wall, Wolfgang A.; Adams, Nikolaus A.
2016-02-01
We present a loosely coupled approach for the solution of fluid-structure interaction problems between a compressible flow and a deformable structure. The method is based on staggered Dirichlet-Neumann partitioning. The interface motion in the Eulerian frame is accounted for by a conservative cut-cell Immersed Boundary method. The present approach enables sub-cell resolution by considering individual cut-elements within a single fluid cell, which guarantees an accurate representation of the time-varying solid interface. The cut-cell procedure inevitably leads to non-matching interfaces, demanding for a special treatment. A Mortar method is chosen in order to obtain a conservative and consistent load transfer. We validate our method by investigating two-dimensional test cases comprising a shock-loaded rigid cylinder and a deformable panel. Moreover, the aeroelastic instability of a thin plate structure is studied with a focus on the prediction of flutter onset. Finally, we propose a three-dimensional fluid-structure interaction test case of a flexible inflated thin shell interacting with a shock wave involving large and complex structural deformations.
Švent, Nejc
2016-01-01
This thesis focuses on the structural analysis of aluminium structural members in accordance with the SIST EN 1999-1-1 standard. In the introduction, historical development of aluminium is summarized, as well as the processes of structural aluminium production and manufacture. Predominantly, resistance control checks of aluminium structural members are covered, with special attention to the major contrasts between aluminium and steel structural analyses. Finally, fundamental examples of resis...
Electronic structure of superheavy elements
The electronic structure of superheavy elements, from element 121 to 131, studied using the relativistic density-functional theory with quantum electrodynamical corrections (Berit interaction) by MacDonald and Vosko, is reported. These corrections give rise to a modification to previous results, and the g electron is found to appear from element 126. Since a recent study on molecular systems has clarified the surprising accuracy of the density-functional approach in evaluating the relative energy difference of ground and excited states, a further study of the electronic configuration of heavy elements using the relativistic density-functional theory and the further improvement of the theory are both awaited. (author)
Lkhamsuren Bayarjargal
2011-09-01
Full Text Available Transition metal nitrides, carbides and borides have a high potential for industrial applications as they not only have a high melting point but are generally harder and less compressible than the pure metals. Here we summarize recent advances in the synthesis of binary transition metal nitrides, carbides and borides focusing on the reaction of the elements at extreme conditions generated within the laser-heated diamond anvil cell. The current knowledge of their structures and high-pressure properties like high-(p; T stability, compressibility and hardness is described as obtained from experiments.
... Thyroid & Parathyroid Glands Adrenal Gland Pancreas Gonads Other Endocrine Glands Review Quiz Cardiovascular System Heart Structure of the Heart Physiology of the Heart Blood Classification & Structure of Blood ...
Logical elements in living cells.
Kremen, A
1984-11-01
Recognition processes with enhanced accuracy (as performed by structures like enzymes or ribosomes) are investigated using elementary ideas of statistical mechanics and related concepts of thermodynamics. The analysis starts from a formal definition of recognition and provides a correspondence with appropriate physical properties of the macromolecular logical elements. Transitions of the recognizing system between different modifications are a necessary feature of a more exacting recognition process. Rearrangement steps provide the process with higher accuracy by performing two physical operations: (1) rearranging the phase space of the system so that the "correct" states be better separated from the "wrong" states and the probability of occupation of the "correct" states be enhanced, (2) directing the process toward the more favourable modifications thus formed. Both operations are related to changes in the physical properties of the recognizing system. These changes can be expressed as differences of macromolecular Gibbs energy levels; if ligand binding or release participate in a step, directivity of the step depends also on the actual chemical potentials of the ligands in solution. The two operations just mentioned resemble two basic operations known to be necessary in electronic digital networks: directivity of control and signal standardization. An analysis of the entire reaction catalysed by a macromolecular logical element takes into account the requirements imposed by the logical functions as well as the need that the chemical potential of the product be not restricted to very low values. To satisfy these conditions, the reaction must be supported by a so-called non-specific reaction, usually implemented by the cleavage reaction of a nucleoside triphosphate. PMID:6513567
Structural elements design manual working with Eurocodes
Draycott, Trevor
2009-01-01
Structural Elements Design Manual: Working With Eurocodes is the structural engineers 'companion volume' to the four Eurocodes on the structural use of timber, concrete, masonry and steelwork. For the student at higher technician or first degree level it provides a single source of information on the behaviour and practical design of the main elements of the building structure. With plenty of worked examples and diagrams, it is a useful textbook not only for students of structural and civil engineering, but also for those on courses in related subjects such as
Advanced finite element method in structural engineering
Long, Yu-Qiu; Long, Zhi-Fei
2009-01-01
This book systematically introduces the research work on the Finite Element Method completed over the past 25 years. Original theoretical achievements and their applications in the fields of structural engineering and computational mechanics are discussed.
HTGR fuel element structural design considerations
The structural design of the large HTGR prismatic core fuel elements involve the interaction of four engineering disciplines: nuclear physics, thermo-hydraulics, structural and material science. Fuel element stress analysis techniques and the development of structural criteria are discussed in the context of an overview of the entire design process. The core of the proposed 2240 MW(t) HTGR is described as an example where the design process was used. Probabalistic stress analysis techniques coupled with probabalistic risk analysis (PRA) to develop structural criteria to account for uncertainty are described. The PRA provides a means for ensuring that the proposed structural criteria are consistent with plant investment and safety risk goals. The evaluation of cracked fuel elements removed from the Fort St. Vrain reactor in the USA is discussed in the context of stress analysis uncertainty and structural criteria development
Fire resistance of stainless steel structural elements
Gomboši, Jana
2015-01-01
Graduation thesis represents behavior of structural elements made from stainless steel in case of fire. The general rules according to the European standard SIST EN 1993-1-2 to determine design resistance of the steel structural element for fire conditions are presented. The main focus was to determinate behavior of stainless steel column exposed to the standard fire. Buckling resistance of the column was calculated with a simplified method from the standard SIST EN 1993-1-2. Mech...
Adaptive finite element strategies for shell structures
Stanley, G.; Levit, I.; Stehlin, B.; Hurlbut, B.
1992-01-01
The present paper extends existing finite element adaptive refinement (AR) techniques to shell structures, which have heretofore been neglected in the AR literature. Specific challenges in applying AR to shell structures include: (1) physical discontinuities (e.g., stiffener intersections); (2) boundary layers; (3) sensitivity to geometric imperfections; (4) the sensitivity of most shell elements to mesh distortion, constraint definition and/or thinness; and (5) intrinsic geometric nonlinearity. All of these challenges but (5) are addressed here.
Origin of complex crystal structures of elements at pressure
Ackland, G. J.; Macleod, I. R.; Degtyareva, O
2003-01-01
We present a unifying theory for the observed complex structures of the sp-bonded elements under pressure based on nearly free electron picture (NFE). In the intermediate pressure regime the dominant contribution to crystal structure arises from Fermi-surface Brillouin zone (FSBZ) interactions - structures which allow this are favoured. This simple theory explains the observed crystal structures, transport properties, the evolution of internal and unit cell parameters with pressure. We illust...
The Electronic Structure of Heavy Element Complexes
Bursten, Bruce E.
2000-07-25
The area of study is the bonding in heavy element complexes, and the application of more sophisticated electronic structure theories. Progress is recounted in several areas: (a) technological advances and current methodologies - Relativistic effects are extremely important in gaining an understanding of the electronic structure of compounds of the actinides, transactinides, and other heavy elements. Therefore, a major part of the continual benchmarking was the proper inclusion of the appropriate relativistic effects for the properties under study. (b) specific applications - These include organoactinide sandwich complexes, CO activation by actinide atoms, and theoretical studies of molecules of the transactinide elements. Finally, specific directions in proposed research are described.
Distribution of inorganic elements in single cells of Chara corallina
There are actually 20 chemical elements necessary or beneficial for plant growth. Carbon, hydrogen, and oxygen are supplied by air and water. The six macronutrients, nitrogen, phosphorus, potassium., calcium, magnesium, and sulfur are required by plants in large amounts. The rest of the elements are required in trace amounts (micronutrients). Essential trace elements include boron, chlorine, copper, iron, manganese, sodium, zinc, molybdenum, and nickel. Beneficial mineral elements include silicon and cobalt. The functions of the inorganic elements closely related to their destinations in plant cells. Plant cells have unique structures, including a central vacuole, plastids, and a thick cell wall that surrounds the cell membrane. Generally, it is very difficult to determine concentrations of inorganic elements in a single plant cell. Chara corallina is a freshwater plant that inhabits temperate zone ponds and lakes. It consists of alternating nodes and internodes. Each internodal segment is a single large cell, up to 10 cm in length, and 1 mm in diameter. With this species it was possible to isolate subcellular fractions with surgical methods with minimal risk of cross contamination. In this study, concentrations of magnesium, calcium, manganese, iron, copper, zinc, and molybdenum in the cell wall, cytoplasm, and vacuole of single cells of Chara corallina were determined by inductively coupled plasma mass spectrometry (ICP-MS). The distribution characteristics of these elements in the cell components were discussed.
Design elements of hot cell facility
Park, D. K.; Lee, K. S.; Baek, S. Y.; Ahn, Y. S.; Choo, Y. S
1997-06-01
Hot cell facility is necessary for the post-irradiation examinations of nuclear fuels and materials. Therefore many hot cell facilities have been constructed and operating to support the research and development on the nuclear technology. In this report, the design elements of the hot cell facility is reviewed and discussed. (author). 3 tabs., 12 figs
Finite-Element Modeling For Structural Analysis
Min, J. B.; Androlake, S. G.
1995-01-01
Report presents study of finite-element mathematical modeling as used in analyzing stresses and strains at joints between thin, shell-like components (e.g., ducts) and thicker components (e.g., flanges or engine blocks). First approach uses global/local model to evaluate system. Provides correct total response and correct representation of stresses away from any discontinuities. Second approach involves development of special transition finite elements to model transitions between shells and thicker structural components.
Will Finite Elements Replace Structural Mechanics?
Ojalvo, I. U.
1984-01-01
This paper presents a personal view regarding the need for a continued interest and activity in structural methods in general, while viewing finite elements and the computer as simply two specific tools for assisting in this endeavor. An attempt is made to provide some insight as to why finite element methods seem to have "won the war," and to give examples of their more (and less) intelligent use. Items addressed include a highlight of unnecessary limitations of many existing standard finite element codes and where it is felt that further development work is needed.
Infinte Periodic Structure of Lightweight Elements
Domadiya, Parthkumar Gandalal; Andersen, Lars Vabbersgaard; Sorokin, Sergey
2013-01-01
models of a semi-infinite Euler-Bernoulli and Timoshenko beam structure with periodic variation of the cross-sectional properties are analyzed. In case of the Euler-Bernoulli beam, vibrational behavior is studied in two dimensions by finite element analysis and Floquet theory. Wave propagation within the...... proper dynamic assessment of lightweight buildings. Instead, this paper discusses and compares the use of finite element analysis and a wave approach based on Floquet theory. The present analysis has focus on the effect of periodicity on vibration transmission within semi-infinite beam structures. Two...... models and analytical approaches are compared and analyzed. A vibration-level distribution and propagation characteristics within the beam are presented for excitation frequencies up to 2 kHz....
Binary Morphology With Spatially Variant Structuring Elements: Algorithm and Architecture
Hedberg, Hugo; Dokladal, Petr; Öwall, Viktor
2009-01-01
Mathematical morphology with spatially variant structuring elements outperforms translation-invariant structuring elements in various applications and has been studied in the literature over the years. However, supporting a variable structuring element shape imposes an overwhelming computational complexity, dramatically increasing with the size of the structuring element. Limiting the supported class of structuring elements to rectangles has allowed for a fast algorithm to be developed, which...
Elemental Compositions of Over 80 Cell Phones
Christian, Beverley; Romanov, Alexandre; Romanova, Irina; Turbini, Laura J.
2014-11-01
Over the last few years, 85 cell phones have been disassembled, ground up, dissolved, and analyzed for elemental content, mainly for information about the metals present in the phones, but also for some metalloids and nonmetals. The following list of 38 elements were detected in some or all of the phones: Be, B, Mg, Al, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Y, Nb, Pd, Ag, In, Sn, Sb, Te, Ba, Ta, W, Pt, Au, Tl, Pb, Bi, Pr, Nd, Sm, Eu, Gd, Tb, Dy, and Er. Cadmium was never detected. This paper discusses the methods used for carrying out the analysis, proposes possible sources in the telephones for the elements of interest, the reasons for the interest in most of the elements, and method repeatability.
BERSAFE: (BERkeley Structural Analysis by Finite Elements)
BERSAFE is a well-known finite element system which has been under continuous use and development for over 20 years. The BERSAFE system comprises an inter-compatible set of program modules covering static stress analysis, linear dynamics and thermal analysis. Data generation and results presentation modules are also available, along with special supporting functions including automatic crack growth through a model with adaptive meshing. The functionality of BERSAFE, is nowadays very advanced, both in engineering scope and finite element technology. It has seen many firsts, including the front solution and Virtual Crack Extension methods (VCE). More recent additions which have developed out of the Power Industry's requirements are a finite element computational fluid dynamics code, FEAT, and engineering design assessment procedures. These procedures include R6 and R5 for the assessment of the integrity of structures containing defects below and within the creep regime. To use all this software in a user-friendly manner, a new computational environment has been developed, called 'The Harness' which takes advantage of modern hardware and software philosophies. This provides the tool-kit to undertake complete problems, covering determination of fluid loads, structural analysis and failure assessment. In the following sections we describe briefly various components of the BERSAFE suite. (author)
Computational structural analysis and finite element methods
Kaveh, A
2014-01-01
Graph theory gained initial prominence in science and engineering through its strong links with matrix algebra and computer science. Moreover, the structure of the mathematics is well suited to that of engineering problems in analysis and design. The methods of analysis in this book employ matrix algebra, graph theory and meta-heuristic algorithms, which are ideally suited for modern computational mechanics. Efficient methods are presented that lead to highly sparse and banded structural matrices. The main features of the book include: application of graph theory for efficient analysis; extension of the force method to finite element analysis; application of meta-heuristic algorithms to ordering and decomposition (sparse matrix technology); efficient use of symmetry and regularity in the force method; and simultaneous analysis and design of structures.
Nonlinear finite element analysis of concrete structures
This report deals with nonlinear finite element analysis of concrete structures loaded in the short-term up until failure. A profound discussion of constitutive modelling on concrete is performed; a model, applicable for general stress states, is described and its predictions are compared with experimental data. This model is implemented in the AXIPLANE-program applicable for axisymmetrick and plane structures. The theoretical basis for this program is given. Using the AXIPLANE-program various concrete structures are analysed up until failure and compared with experimental evidence. These analyses include panels pressure vessel, beams failing in shear and finally a specific pull-out test, the Lok-Test, is considered. In these analyses, the influence of different failure criteria, aggregate interlock, dowel action, secondary cracking, magnitude of compressive strenght, magnitude of tensile strenght and of different post-failure behaviours of the concrete are evaluated. Moreover, it is shown that a suitable analysis of the theoretical data results in a clear insight into the physical behaviour of the considered structures. Finally, it is demonstrated that the AXISPLANE-program for widely different structures exhibiting very delicate structural aspects gives predictions that are in close agreement with experimental evidence. (author)
Electronic structure theory of the superheavy elements
Eliav, Ephraim; Fritzsche, Stephan; Kaldor, Uzi
2015-12-01
High-accuracy calculations of atomic properties of the superheavy elements (SHE) up to element 122 are reviewed. The properties discussed include ionization potentials, electron affinities and excitation energies, which are associated with the spectroscopic and chemical behavior of these elements, and are therefore of considerable interest. Accurate predictions of these quantities require high-order inclusion of relativity and electron correlation, as well as large, converged basis sets. The Dirac-Coulomb-Breit Hamiltonian, which includes all terms up to second order in the fine-structure constant α, serves as the framework for the treatment; higher-order Lamb shift terms are considered in some selected cases. Electron correlation is treated by either the multiconfiguration self-consistent-field approach or by Fock-space coupled cluster theory. The latter is enhanced by the intermediate Hamiltonian scheme, allowing the use of larger model (P) spaces. The quality of the calculations is assessed by applying the same methods to lighter homologs of the SHEs and comparing with available experimental information. Very good agreement is obtained, within a few hundredths of an eV, and similar accuracy is expected for the SHEs. Many of the properties predicted for the SHEs differ significantly from what may be expected by straightforward extrapolation of lighter homologs, demonstrating that the structure and chemistry of SHEs are strongly affected by relativity. The major scientific challenge of the calculations is to find the electronic structure and basic atomic properties of the SHE and assign its proper place in the periodic table. Significant recent developments include joint experimental-computational studies of the excitation spectrum of Fm and the ionization energy of Lr, with excellent agreement of experiment and theory, auguring well for the future of research in the field.
Electrical connection structure for a superconductor element
Lallouet, Nicolas; Maguire, James
2010-05-04
The invention relates to an electrical connection structure for a superconductor element cooled by a cryogenic fluid and connected to an electrical bushing, which bushing passes successively through an enclosure at an intermediate temperature between ambient temperature and the temperature of the cryogenic fluid, and an enclosure at ambient temperature, said bushing projecting outside the ambient temperature enclosure. According to the invention, said intermediate enclosure is filled at least in part with a solid material of low thermal conductivity, such as a polyurethane foam or a cellular glass foam. The invention is applicable to connecting a superconductor cable at cryogenic temperature to a device for equipment at ambient temperature.
De la Fuente, Ildefonso M.; Cortes, Jesus M.; Perez-Pinilla, Martin B.; Ruiz-Rodriguez, Vicente; Veguillas, Juan
2011-01-01
Background Experimental observations and numerical studies with dissipative metabolic networks have shown that cellular enzymatic activity self-organizes spontaneously leading to the emergence of a metabolic core formed by a set of enzymatic reactions which are always active under all environmental conditions, while the rest of catalytic processes are only intermittently active. The reactions of the metabolic core are essential for biomass formation and to assure optimal metabolic performance. The on-off catalytic reactions and the metabolic core are essential elements of a Systemic Metabolic Structure which seems to be a key feature common to all cellular organisms. Methodology/Principal Findings In order to investigate the functional importance of the metabolic core we have studied different catalytic patterns of a dissipative metabolic network under different external conditions. The emerging biochemical data have been analysed using information-based dynamic tools, such as Pearson's correlation and Transfer Entropy (which measures effective functionality). Our results show that a functional structure of effective connectivity emerges which is dynamical and characterized by significant variations of bio-molecular information flows. Conclusions/Significance We have quantified essential aspects of the metabolic core functionality. The always active enzymatic reactions form a hub –with a high degree of effective connectivity- exhibiting a wide range of functional information values being able to act either as a source or as a sink of bio-molecular causal interactions. Likewise, we have found that the metabolic core is an essential part of an emergent functional structure characterized by catalytic modules and metabolic switches which allow critical transitions in enzymatic activity. Both, the metabolic core and the catalytic switches in which also intermittently-active enzymes are involved seem to be fundamental elements in the self-regulation of the Systemic
Work on the development of the structure of fuel elements
This paper is meant to give a roundup of development work concerning fuel element structure as support and cladding of fuel rods. The fuel element structure is a link between reactor vessel and the power-producing fuel rods, i.e. both the reactor arrangement and fuel rods influence the design of the fuel element structure, whereas the fuel element structure also determine marginal conditions for plant and fuel rods. (orig./RW)
Incorporation of trace elements into hair structure
Examining blood and urine provides an immense insight into human diseases. It is natural to hope that the hair studies will be added routinely to the examinations. Human head hair is a recording filament which can reflect metabolic changes of many elements over a long period of time. The idea of hair analysis is very inviting, because hair is easily samples, shipped and analyzed. In this paper the authors propose a method for the determination of some diffusion parameters from experimental data on the distribution of trace element concentrations in hair and then a method for the determination of the radial diffusion constants of Se, Zn and Pb. The authors' model of hair structure with respect to diffusion is based on the supposition of cross-sectional homogeneity as well as the longitudinal homogeneity of hair. This supposition implies nonisotropic diffusion in hair which is described by two diffusion constants. Diffusion constants can be determined by experiment on wetting hair in solvents or by measurements of natural contamination of hair in air. The first type of experiments can be arranged in various ways to separate radial diffusion from the longitudinal one and, consequently, to determine two diffusion constants from various sets of experiments. The authors' aim is to consider only radial diffusion in hair and to determine the radial diffusion constants of Se, Zn and Pb
Trace elements in sickle cell disease
Instrumental Neutron Activation Analysis (INAA) and Proton-Induced X-ray Emission (PIXE) analysis (employed as a complementary technique) have been used to determine the concentration of 11 elements in blood samples and its components erythrocytes and plasma obtained from three groups of subjects in Nigeria viz: sickle cell anaemia (SCA) subjects, subjects with sickle cell trait and normal control subjects. The results suggest that SCA subjects have significantly higher concentrations of Na, Cl, Ca and Cu in their whole blood and erythrocytes and a higher concentration of Cl and Cu in their plasma relative to control subjects. Furthermore, a significantly lower concentration of K, Fe, Zn, Se, Br and Rb were found in the whole blood and erythrocytes of the SCA subjects as compared to the controls while the concentration of K and Fe in the plasma of the SCA subjects were however, found to be significantly higher than that of the control group. The study also shows that there were no significant differences between the concentration of these 11 elements in the group with sickle cell trait and the normal control group. (author) 20 refs.; 4 tabs
Analysis of trace elements in chicken embryo cells
A scanning proton microprobe (SPM) with high resolution and high sensitivity was applied to analyze trace elements in chicken embryo forebrain neutron cell and skeletal muscle myotube cell. The absorption of the two different cells to zinc ions, correlation of elements and trace elemental distributions in the cells were studied. The results indicate that the absorptive capacity of the chicken embryo forebrain neuron cell to zinc ions is larger than that of the chicken embryo skeletal muscle myotube cell, and the concentrations of intracellular trace elements such as Cr, Fe, Ni are explicitly higher. The correlations of elements such as S and Zn or Fe and Zn are positive, but the correlations of P and Ni or Cr and Fe are negative. From the maps of cellular elemental distribution the contents of the different elements are different in the intracellular parts, for example, the contents of the elements phosphorus, sulfur, potassium in the cell membranes are higher than that in the cells
Tensegrity finite element models of mechanical tests of individual cells.
Bursa, Jiri; Lebis, Radek; Holata, Jakub
2012-01-01
A three-dimensional finite element model of a vascular smooth muscle cell is based on models published recently; it comprehends elements representing cell membrane, cytoplasm and nucleus, and a complex tensegrity structure representing the cytoskeleton. In contrast to previous models of eucaryotic cells, this tensegrity structure consists of several parts. Its external and internal parts number 30 struts, 60 cables each, and their nodes are interconnected by 30 radial members; these parts represent cortical, nuclear and deep cytoskeletons, respectively. This arrangement enables us to simulate load transmission from the extracellular space to the nucleus or centrosome via membrane receptors (focal adhesions); the ability of the model was tested by simulation of some mechanical tests with isolated vascular smooth muscle cells. Although material properties of components defined on the basis of the mechanical tests are ambiguous, modelling of different types of tests has shown the ability of the model to simulate substantial global features of cell behaviour, e.g. "action at a distance effect" or the global load-deformation response of the cell under various types of loading. Based on computational simulations, the authors offer a hypothesis explaining the scatter of experimental results of indentation tests. PMID:22508025
ADAPTIVE FINITE ELEMENT METHOD FOR HIGH-SPEED FLOW-STRUCTURE INTERACTION
Wiroj LIMTRAKARN; Pramote DECHAUMPHAI
2004-01-01
An adaptive finite element method for high-speed flow-structure interaction is presented. The cell-centered finite element method is combined with an adaptive meshing technique to solve the Navier-Stokes equations for high-speed compressible flow behavior. The energy equation and the quasi-static structural equations for aerodynamically heated structures are solved by applying the Galerkin finite element method. The finite element formulation and computational procedure are described. Interactions between the high-speed flow, structural heat transfer, and deformation are studied by two applications of Mach 10 flow over an inclined plate, and Mach 4 flow in a channel.
Finite Element Vibration and Dynamic Response Analysis of Engineering Structures
Jaroslav Mackerle
2000-01-01
Full Text Available This bibliography lists references to papers, conference proceedings, and theses/dissertations dealing with finite element vibration and dynamic response analysis of engineering structures that were published from 1994 to 1998. It contains 539 citations. The following types of structures are included: basic structural systems; ground structures; ocean and coastal structures; mobile structures; and containment structures.
Seismic evaluation of a hot cell structure
The evaluation of the structural capacity of and the seismic demand on an existing hot cell structure in a nuclear facility is described. An ANSYS finite-element model of the cell was constructed, treating the walls as plates and the floor and ceiling as a system of discrete beams. A modal analysis showed that the fundamental frequencies of the cell walls lie far above the earthquake frequency range. An equivalent static analysis of the structure was performed. Based on the analysis it was demonstrated that the hot cell structure, would readily withstand the evaluation basis earthquake
Finite element analysis for general elastic multi-structures
HUANG; Jianguo; SHI; Zhongci; XU; Yifeng
2006-01-01
A finite element method is introduced to solve the general elastic multi-structure problem, in which the displacements on bodies, the longitudinal displacements on plates and the longitudinal displacements on beams are discretized using conforming linear elements, the rotational angles on beams are discretized using conforming elements of second order, the transverse displacements on plates and beams are discretized by the Morley elements and the Hermite elements of third order, respectively. The generalized Korn's inequality is established on related nonconforming element spaces, which implies the unique solvability of the finite element method. Finally, the optimal error estimate in the energy norm is derived for the method.
Teaching Finite Element Method of Structural Line Elements Assisted by Open Source FreeMat
Waluyo Adi Siswanto; Agung Setyo Darmawan
2012-01-01
One of the important objectives in teaching finite element method at introductory level is to bring students into the comprehension of finite element procedures. This study presents a strategy of teaching structural line elements involving an open source computer-aided learning tool FreeMat integrated with another open source CALFEM finite element toolbox. FreeMat, which is a programming based learning tool, is used together with other higher level learning tools; Open/Libre Office Spreadshee...
Vertical velocity structure and geometry of clear air convective elements
Rowland, J. R.; Arnold, A.
1975-01-01
The paper discusses observations of individual convective elements with a high-power narrow-beam scanning radar, an FM-CW radar, and an acoustic sounder, including the determination of the vertical air velocity patterns of convective structures with the FM-CW radar and acoustic sounder. Data are presented which link the observed velocity structure and geometrical patterns to previously proposed models of boundary layer convection. It is shown that the high-power radar provides a clear three-dimensional picture of convective cells and fields over a large area with a resolution of 150 m, where the convective cells are roughly spherical. Analysis of time-height records of the FM-CW radar and acoustic sounder confirms the downdraft-entrainment mechanism of the convective cell. The Doppler return of the acoustic sounder and the insect-trail slopes on FM-CW radar records are independent but redundant methods for obtaining the vertical velocity patterns of convective structures.
Prefabricated elements and structures: Developments, tests and experiences
Goltermann, Per
2014-01-01
Danish concrete structures are often built with prefabricated elements, joined together on the site and this provides a large challenge to constantly improve and optimize the elements, the joints and the models. DTU Byg has been active in the development, testing and modelling of new elements, joints and models and a number of results and experiences are presented in the paper.
Mei, Chuh; Pates, Carl S., III
1994-01-01
A coupled boundary element (BEM)-finite element (FEM) approach is presented to accurately model structure-acoustic interaction systems. The boundary element method is first applied to interior, two and three-dimensional acoustic domains with complex geometry configurations. Boundary element results are very accurate when compared with limited exact solutions. Structure-interaction problems are then analyzed with the coupled FEM-BEM method, where the finite element method models the structure and the boundary element method models the interior acoustic domain. The coupled analysis is compared with exact and experimental results for a simplistic model. Composite panels are analyzed and compared with isotropic results. The coupled method is then extended for random excitation. Random excitation results are compared with uncoupled results for isotropic and composite panels.
RILEM TC : reinforcement of timber elements in existing structures
Tannert, Thomas; Branco, Jorge M.; Riggio, Mariapaola
2013-01-01
The paper reports on the activities of the RILEM technical committee “Reinforcement of Timber Elements in Existing Structures”. The main objective of the committee is to coordinate the efforts to improve the reinforcement practice of timber structural elements. Recent developments related to structural reinforcements can be grouped into three categories: (i) addition of new structural systems to support the existing structure; (ii) configuration of a composite system; and (iii)...
Finite element models applied in active structural acoustic control
Oude Nijhuis, Marco H.H.; Boer, de André; Rao, Vittal S.
2002-01-01
This paper discusses the modeling of systems for active structural acoustic control. The finite element method is applied to model structures including the dynamics of piezoelectric sensors and actuators. A model reduction technique is presented to make the finite element model suitable for controll
Pottmann, Helmut
2015-03-03
This paper is an overview of architectural structures which are either composed of polyhedral cells or closely related to them. We introduce the concept of a support structure of such a polyhedral cell packing. It is formed by planar quads and obtained by connecting corresponding vertices in two combinatorially equivalent meshes whose corresponding edges are coplanar and thus determine planar quads. Since corresponding triangle meshes only yield trivial structures, we focus on support structures associated with quad meshes or hex-dominant meshes. For the quadrilateral case, we provide a short survey of recent research which reveals beautiful relations to discrete differential geometry. Those are essential for successfully initializing numerical optimization schemes for the computation of quad-based support structures. Hex-dominant structures may be designed via Voronoi tessellations, power diagrams, sphere packings and various extensions of these concepts. Apart from the obvious application as load-bearing structures, we illustrate here a new application to shading and indirect lighting. On a higher level, our work emphasizes the interplay between geometry, optimization, statics, and manufacturing, with the overall aim of combining form, function and fabrication into novel integrated design tools.
Structural analysis of reactor fuel elements
An overview of fuel-element modeling is presented that traces the development of codes for the prediction of light-water-reactor and fast-breeder-reactor fuel-element performance. It is concluded that although the mathematical analysis is now far advanced, the development and incorporation of mechanistic constitutive equations has not kept pace. The resultant reliance on empirical correlations severely limits the physical insight that can be gained from code extrapolations. Current efforts include modeling of alternate fuel systems, analysis of local fuel-cladding interactions, and development of a predictive capability for off-normal behavior. Future work should help remedy the current constitutive deficiencies and should include the development of deterministic failure criteria for use in design
Reliability of Structural Systems with Correlated Elements
Thoft-Christensen, Palle; Sørensen, John Dalsgaard
1982-01-01
Calculation of the probability of failure of a system with correlation members is usually a difficult and time-consuming numerical problem. However, for some types of systems with equally correlated elements this calculation can be performed in a simple way. This has suggested two new methods bas...... on so-called average and equivalent correlation coefficients. By using these methods approximate values for the probability of failure can easily be calculated. The accuracy of these methods is illustrated with examples.......Calculation of the probability of failure of a system with correlation members is usually a difficult and time-consuming numerical problem. However, for some types of systems with equally correlated elements this calculation can be performed in a simple way. This has suggested two new methods based...
Fastening elements in concrete structures - numerical simulations
Ozbolt, Josko; Eligehausen, Rolf
1993-01-01
Anchoring elements such as headed and expansion studs and grouted or undercut anchors, are often used for local transfer of loads into concrete members. In order to better understand the failure mechanism, a large number of experiments have been carried out in the past. However, due to the complicated three-dimensional load transfer a very few or no numerical studies have been performed for a number of different fastening situations i.e. influence of the embedment depth, crack-width inftuence...
Structural analysis with the finite element method linear statics
Oñate, Eugenio
2013-01-01
STRUCTURAL ANALYSIS WITH THE FINITE ELEMENT METHOD Linear Statics Volume 1 : The Basis and Solids Eugenio Oñate The two volumes of this book cover most of the theoretical and computational aspects of the linear static analysis of structures with the Finite Element Method (FEM). The content of the book is based on the lecture notes of a basic course on Structural Analysis with the FEM taught by the author at the Technical University of Catalonia (UPC) in Barcelona, Spain for the last 30 years. Volume1 presents the basis of the FEM for structural analysis and a detailed description of the finite element formulation for axially loaded bars, plane elasticity problems, axisymmetric solids and general three dimensional solids. Each chapter describes the background theory for each structural model considered, details of the finite element formulation and guidelines for the application to structural engineering problems. The book includes a chapter on miscellaneous topics such as treatment of inclined supports, elas...
Structural Elements in Franz Kafka's "The Metamorphosis."
Johnson, Scott
1993-01-01
Notes that Kafka's "The Metamorphosis" is not only a masterpiece of modern literature but also a work that exemplifies many ideas of structural family therapy. Examines how Kafka's novella embodies concepts such as parentified children, enmeshment, intergenerational boundaries, coalitions and triangles, structural dysfunction, and structural…
Mechanics of structural elements theory and applications
Slivker, Vladimir
2006-01-01
Using the variational approach, this book presents the variational principles and methods of analysis for applied elasticity and structural mechanics. Oriented towards experts in civil engineering, researchers, and software developers, this book is also useful to students of engineering, and to professors of structural analysis.
Statistical study on the strength of structural materials and elements
Strength data for structural materials and elements including concrete, reinforcing steel, structural steel, plywood elements, reinforced concrete beams, reinforced concrete columns, brick masonry elements, and concrete masonry walls were statistically analyzed. Sample statistics were computed for these data, and distribution parameters were derived for normal, lognormal, and Weibull distributions. Goodness-of-fit tests were performed on these distributions. Most data, except those for masonry elements, displayed fairly small dispersion. Dispersion in data for structural materials was generally found to be smaller than for structural elements. Lognormal and Weibull distributions displayed better overall fits to data than normal distribution, although either Weibull or lognormal distribution can be used to represent the data analyzed. (auth)
Finite element models applied in active structural acoustic control
Oude Nijhuis, Marco H.H.; de Boer; Rao, Vittal S.
2002-01-01
This paper discusses the modeling of systems for active structural acoustic control. The finite element method is applied to model structures including the dynamics of piezoelectric sensors and actuators. A model reduction technique is presented to make the finite element model suitable for controller design. The reduced structural model is combined with an acoustic model which uses the radiation mode concept. For a test case consisting of a rectangular plate with one piezo patch the model re...
In this study, we investigate the effect of different elemental selenium to elemental sulfur ratios on the chalcopyrite phase formation in Cu(In,Ga)(S,Se)2 thin films. The films are formed by the stacked elemental layer process. The structural and electronic properties of the thin films and solar cells are analyzed by means of scanning electron microscopy, glow discharge optical emission spectrometry, X-ray diffraction, X-ray fluorescence, Raman spectroscopy, spectral photoluminescence as well as current-voltage, and quantum efficiency measurements. The influence of different S/(S+Se) ratios on the anion incorporation and on the Ga/In distribution is investigated. We find a homogenous sulfur concentration profile inside the film from the top surface to the bottom. External quantum efficiency measurements show that the band edge of the solar cell device is shifted to shorter wavelength, which enhances the open-circuit voltages. The relative increase of the open-circuit voltage with S/(S+Se) ratio is lower than expected from the band gap energy trend, which is attributed to the presence of S-induced defects. We also observe a linear decrease of the short-circuit current density with increasing S/(S+Se) ratio which can be explained by a reduced absorption. Above a critical S/(S+Se) ratio of around 0.61, the fill factor drops drastically, which is accompanied by a strong series resistance increase which may be attributed to changes in the back contact or p-n junction properties.
Mueller, B. J., E-mail: bjm.mueller@web.de [Robert Bosch GmbH, Corporate Research and Advance Engineering, Advanced Functional Materials and Microsystems, D-70839 Gerlingen (Germany); Institute of Micro- and Nanomaterials, University of Ulm, D-89081 Ulm (Germany); Zimmermann, C.; Haug, V., E-mail: veronika.haug@de.bosch.com; Koehler, T.; Zweigart, S. [Robert Bosch GmbH, Corporate Research and Advance Engineering, Advanced Functional Materials and Microsystems, D-70839 Gerlingen (Germany); Hergert, F. [Bosch Solar CISTech GmbH, D-14772 Brandenburg (Germany); Herr, U., E-mail: ulrich.herr@uni-ulm.de [Institute of Micro- and Nanomaterials, University of Ulm, D-89081 Ulm (Germany)
2014-11-07
In this study, we investigate the effect of different elemental selenium to elemental sulfur ratios on the chalcopyrite phase formation in Cu(In,Ga)(S,Se){sub 2} thin films. The films are formed by the stacked elemental layer process. The structural and electronic properties of the thin films and solar cells are analyzed by means of scanning electron microscopy, glow discharge optical emission spectrometry, X-ray diffraction, X-ray fluorescence, Raman spectroscopy, spectral photoluminescence as well as current-voltage, and quantum efficiency measurements. The influence of different S/(S+Se) ratios on the anion incorporation and on the Ga/In distribution is investigated. We find a homogenous sulfur concentration profile inside the film from the top surface to the bottom. External quantum efficiency measurements show that the band edge of the solar cell device is shifted to shorter wavelength, which enhances the open-circuit voltages. The relative increase of the open-circuit voltage with S/(S+Se) ratio is lower than expected from the band gap energy trend, which is attributed to the presence of S-induced defects. We also observe a linear decrease of the short-circuit current density with increasing S/(S+Se) ratio which can be explained by a reduced absorption. Above a critical S/(S+Se) ratio of around 0.61, the fill factor drops drastically, which is accompanied by a strong series resistance increase which may be attributed to changes in the back contact or p-n junction properties.
Response Surface Stochastic Finite Element Method of Composite Structure
Cai Deyong
2016-01-01
Full Text Available Response Surface Method (RSM has been applied to structural reliability problems successfully in many areas. Finite Element Method (FEM is one of the most widely used computational methods, which permit the analysis and design of large-scale engineering systems. In order to obtain a reliability analysis method of composite structure with satisfactory accuracy and computational efficiency, RSM and FEM were combined by secondary development of ABAQUS. Response Surface Stochastic Finite Element Method (RSSFEM which can solve the reliability problems of composite structure was developed. The numerical accuracy and the computational efficiency of the developed method were demonstrated by comparison with Monte-Carlo Stochastic Finite Element Method (MCSFEM.
Alpha Decay, Shell Structure, and New Elements
PENZhong-Zhou; TAIFei; SHENWen-Qing
2003-01-01
We systematically analyze the experimental data of alpha decay in even-even heavy nuclei far from stability and find that the Geiger-Nuttall law brea~s for an isotopic chain when its neutron number is across a marc number or there is a deformed subshell. This break can be used to identify new magic numbers of superheavy nuclei. It is also discovered that there is a new linear relation between the logarithm of half-life and the reciprocal of the square root of decay energy for N = 126 and N = 152 isotones. It could be a new law of alpha decay for nuclei with magic neutron numbers but the physics behind it is to be explored. The significance of these researches for the search of new elements is discussed.
Results of galois field elements multipliers structural complexity evaluation
Hlukhova, Alexandra
2013-01-01
Scalable multiplier for Galois field GF(2m) elements core generator operation is examined. The multiplier uses type 2 Gaussian normal basis for Galois field elements presentation and forms m-bit (m≤998) result by n-bit portions. Generated cores hardware complexity allows their implementation in FPGA for any m and n values. But for big m and n values implementation is impossible because of high structural complexity. The method for such multipliers structural complexity estimation is propos...
sp3-hybridized framework structure of group-14 elements discovered by genetic algorithm
Nguyen, Manh Cuong; Zhao, Xin; Wang, Cai-Zhuang; Ho, Kai-Ming
2014-05-01
Group-14 elements, including C, Si, Ge, and Sn, can form various stable and metastable structures. Finding new metastable structures of group-14 elements with desirable physical properties for new technological applications has attracted a lot of interest. Using a genetic algorithm, we discovered a new low-energy metastable distorted sp3-hybridized framework structure of the group-14 elements. It has P42/mnm symmetry with 12 atoms per unit cell. The void volume of this structure is as large as 139.7Å3 for Si P42/mnm, and it can be used for gas or metal-atom encapsulation. Band-structure calculations show that P42/mnm structures of Si and Ge are semiconducting with energy band gaps close to the optimal values for optoelectronic or photovoltaic applications. With metal-atom encapsulation, the P42/mnm structure would also be a candidate for rattling-mediated superconducting or used as thermoelectric materials.
Finite-element method for above-core structures
Three-dimensional finite-element models for the treatment of the nonlinear, transient response of a fast breeder reactor's above-core structures are described. For purposes of treating arbitrarily large rotations, node orientations are described by unit vectors and the deformable elements are treated by a corotational formulation in which the coordinate system is embedded in the elements. Deformable elements may be connected either to nodes directly or through rigid bodies. The time integration is carried out by the Newmark β method. These features have been incorporated to form the finite-element program SAFE/RAS (Safety Analysis by Finite Elements/Reactor Analysis and Safety Division). Computations are presented for semianalytical comparisons, simple scoping studies, and Stanford Research Institute (SRI) test comparisons
Vemaganti, Gururaja R.; Wieting, Allan R.
1990-01-01
A higher-order streamline upwinding Petrov-Galerkin finite element method is employed for high speed viscous flow analysis using structured and unstructured meshes. For a Mach 8.03 shock interference problem, successive mesh adaptation was performed using an adaptive remeshing method. Results from the finite element algorithm compare well with both experimental data and results from an upwind cell-centered method. Finite element results for a Mach 14.1 flow over a 24 degree compression corner compare well with experimental data and two other numerical algorithms for both structured and unstructured meshes.
Incommensurate host-guest structures in compressed elements: Hume—Rothery effects as origin
Degtyareva, V. F.
2015-11-01
Discovery of the incommensurate structure in the element Ba under pressure 15 years ago was followed by findings of a series of similar structures in other compressed elements. Incommensurately modulated structures of the host-guest type consist of a tetragonal host structure and a guest structure. The guest structure forms chains of atoms embedded in the channels of host atoms so that the axial ratio of these subcells along the c axis is not rational. Two types of the host-guest structures have been found so far: with the host cells containing 8 atoms and 16 atoms; in these both types the guest cells contain 2 atoms. These crystal structures contain a non-integer number of atoms in their unit cell: tI11* in Bi, Sb, As, Ba, Sr, Sc and tI19* in Na, K, Rb. We consider here a close structural relationship of these host-guest structures with the binary alloy phase Au3Cd5-tI32. This phase is related to the family of the Hume-Rothery phases that is stabilized by the Fermi sphere-Brillouin zone interaction. From similar considerations for alkali and alkaline-earth elements a necessary condition for structural stability emerges in which the valence electrons band overlaps with the upper core electrons and the valence electron count increases under compression.
Habib Ammari; Gang Bao
2008-01-01
Consider a time-harmonic electromagnetic plane wave incident on a biperiodic structure in R3. The periodic structure separates two homogeneous regions. The medium inside the structure is chiral and nonhomogeneous. In this paper, variational formulations coupling finite element methods in the chiral medium with a method of integral equations on the periodic interfaces are studied. The well-posedness of the continuous and discretized problems is established. Uniform convergence for the coupling variational approximations of the model problem is obtained.
Stochastic Finite Elements in Reliability-Based Structural Optimization
Sørensen, John Dalsgaard; Engelund, S.
Application of stochastic finite elements in structural optimization is considered. It is shown how stochastic fields modelling e.g. the modulus of elasticity can be discretized in stochastic variables and how a sensitivity analysis of the reliability of a structural system with respect to...
Stochastic Finite Elements in Reliability-Based Structural Optimization
Sørensen, John Dalsgaard; Engelund, S.
1995-01-01
Application of stochastic finite elements in structural optimization is considered. It is shown how stochastic fields modelling e.g. the modulus of elasticity can be discretized in stochastic variables and how a sensitivity analysis of the reliability of a structural system with respect to...
Finite element thermal analysis of convectively-cooled aircraft structures
Wieting, A. R.; Thornton, E. A.
1981-01-01
The design complexity and size of convectively-cooled engine and airframe structures for hypersonic transports necessitate the use of large general purpose computer programs for both thermal and structural analyses. Generally thermal analyses are based on the lumped-parameter finite difference technique, and structural analyses are based on the finite element technique. Differences in these techniques make it difficult to achieve an efficient interface. It appears, therefore, desirable to conduct an integrated analysis based on a common technique. A summary is provided of efforts by NASA concerned with the development of an integrated thermal structural analysis capability using the finite element method. Particular attention is given to the development of conduction/forced-convection finite element methodology and applications which illustrate the capabilities of the developed concepts.
Application of global elements to a reinforced concrete structure
The dimensioning of nuclear facilities requires to take into account the possible risk of earthquakes. However such installations are generally complex structures with reinforced concrete poles, walls, beams and porches. In this study, a seismic analysis of such a structure is proposed. The use of the Castem 2000 global element code was attempted to dynamically simulate the behaviour of the reinforced concrete elements. However, no suitable modeling has been found for the storeys, the functioning of which being dominated by carrying walls. Concerning the porch-type storeys, monotonous static loads were simulated and provided information on the local and global behaviour of these structures. Thus, representative global elements could be realized for these structures. Results obtained are satisfactory for these storeys which essentially undergo a bending deformation. (J.S.)
Hybrid open public space of landscape elements and built structure
Gordana Bence
2008-01-01
Full Text Available The trend today in the cities in Europe and elsewhere is in combining landscape elements, built structure and different uses into a complex urban structure. Physical and program interweaving of landscape elements and built structure enables the consumers daily practice of leisure programs – relaxation, recreation and experiencing other cultural, educational and social events in the public green space. On the basis of determinate social changes and new approaches in urban planning practice, analyses of architectural and urban case studies from the point of view of integrating the landscape elements into the urban structure, the article defines the phenomenon of hybrid open public space and proposes methodical guidelines for the planning.
RSW Mixed Element Cell-Centered Medium Mesh
National Aeronautics and Space Administration — This RSW gridset is designed as the medium size mixed element grid for use with cell-centered unstructured meshes. UG3 : Grid File Name = rsw_med_mixedcc.b8.ugrid...
Oxidation of Elemental Sulfur to Sulfite by Thiobacillus thiooxidans Cells
Suzuki, Isamu; Chan, C W; Takeuchi, T L
1992-01-01
Thiobacillus thiooxidans cells oxidized elemental sulfur to sulfite, with 1 mol of O2 consumption per mol of sulfur oxidized to sulfite, when the oxidation of sulfite was inhibited with 2-n-heptyl-4-hydroxyquinoline N-oxide.
Investigation of the photovoltaic cell/ thermoelectric element hybrid system performance
Cotfas, D. T.; Cotfas, P. A.; Machidon, O. M.; Ciobanu, D.
2016-06-01
The PV/TEG hybrid system, consisting of the photovoltaic cells and thermoelectric element, is presented in the paper. The dependence of the PV/TEG hybrid system parameters on the illumination levels and the temperature is analysed. The maxim power values of the photovoltaic cell, of the thermoelectric element and of the PV/TEG system are calculated and a comparison between them is presented and analysed. An economic analysis is also presented.
Multibody Finite Element Method and Application in Hydraulic Structure Analysis
Chao Su; Yebin Zhao; Yusong Jiang
2015-01-01
Multibody finite element method is proposed for analysis of contact problems in hydraulic structure. This method is based on the block theory of discontinuous deformation analysis (DDA) method and combines advantages of finite element method (FEM) and the displacement compatibility equation in classical elastic mechanics. Each single block is analyzed using FEM in corresponding local coordinate system and all contacting blocks need to satisfy the displacement compatibility requirement between...
Finite elements for the thermomechanical calculation of massive structures
The paper examines the fine element analysis of thermal stress and deformation problems in massive structures. To this end compatible idealizations are utilized for heat conduction and static analysis in order to minimize the data transfer. For transient behaviour due to unsteady heat flow and/or inelastics material processes the two computational parts are interwoven in form of an integrated software package for finite element analysis of thermomechanical problems in space and time. (orig.)
Automated Finite Element Modeling of Wing Structures for Shape Optimization
Harvey, Michael Stephen
1993-01-01
The displacement formulation of the finite element method is the most general and most widely used technique for structural analysis of airplane configurations. Modem structural synthesis techniques based on the finite element method have reached a certain maturity in recent years, and large airplane structures can now be optimized with respect to sizing type design variables for many load cases subject to a rich variety of constraints including stress, buckling, frequency, stiffness and aeroelastic constraints (Refs. 1-3). These structural synthesis capabilities use gradient based nonlinear programming techniques to search for improved designs. For these techniques to be practical a major improvement was required in computational cost of finite element analyses (needed repeatedly in the optimization process). Thus, associated with the progress in structural optimization, a new perspective of structural analysis has emerged, namely, structural analysis specialized for design optimization application, or.what is known as "design oriented structural analysis" (Ref. 4). This discipline includes approximation concepts and methods for obtaining behavior sensitivity information (Ref. 1), all needed to make the optimization of large structural systems (modeled by thousands of degrees of freedom and thousands of design variables) practical and cost effective.
Finite element analysis of structures through unified formulation
Carrera, Erasmo; Petrolo, Marco; Zappino, Enrico
2014-01-01
The finite element method (FEM) is a computational tool widely used to design and analyse complex structures. Currently, there are a number of different approaches to analysis using the FEM that vary according to the type of structure being analysed: beams and plates may use 1D or 2D approaches, shells and solids 2D or 3D approaches, and methods that work for one structure are typically not optimized to work for another. Finite Element Analysis of Structures Through Unified Formulation deals with the FEM used for the analysis of the mechanics of structures in the case of linear elasticity. The novelty of this book is that the finite elements (FEs) are formulated on the basis of a class of theories of structures known as the Carrera Unified Formulation (CUF). It formulates 1D, 2D and 3D FEs on the basis of the same ''fundamental nucleus'' that comes from geometrical relations and Hooke''s law, and presents both 1D and 2D refined FEs that only have displacement variables as in 3D elements. It also covers 1D...
Finite element analysis of degraded concrete structures - Workshop proceedings
This workshop is related to the finite element analysis of degraded concrete structures. It is composed of three sessions. The first session (which title is: the use of finite element analysis in safety assessments) comprises six papers which titles are: Historical Development of Concrete Finite Element Modeling for Safety Evaluation of Accident-Challenged and Aging Concrete Structures; Experience with Finite Element Methods for Safety Assessments in Switzerland; Stress State Analysis of the Ignalina NPP Confinement System; Prestressed Containment: Behaviour when Concrete Cracking is Modelled; Application of FEA for Design and Support of NPP Containment in Russia; Verification Problems of Nuclear Installations Safety Software of Strength Analysis (NISS SA). The second session (title: concrete containment structures under accident loads) comprises seven papers which titles are: Two Application Examples of Concrete Containment Structures under Accident Load Conditions Using Finite Element Analysis; What Kind of Prediction for Leak rates for Nuclear Power Plant Containments in Accidental Conditions; Influence of Different Hypotheses Used in Numerical Models for Concrete At Elevated Temperatures on the Predicted Behaviour of NPP Core Catchers Under Severe Accident Conditions; Observations on the Constitutive Modeling of Concrete Under Multi-Axial States at Elevated Temperatures; Analyses of a Reinforced Concrete Containment with Liner Corrosion Damage; Program of Containment Concrete Control During Operation for the Temelin Nuclear Power Plant; Static Limit Load of a Deteriorated Hyperbolic Cooling Tower. The third session (concrete structures under extreme environmental load) comprised five papers which titles are: Shear Transfer Mechanism of RC Plates After Cracking; Seismic Back Calculation of an Auxiliary Building of the Nuclear Power Plant Muehleberg, Switzerland; Seismic Behaviour of Slightly Reinforced Shear Wall Structures; FE Analysis of Degraded Concrete
The main goal of this research is to establish a methodology of finite element analysis of containment building predicting not only global behaviour but also local failure mode. In this report, we summerize some existing numerical analysis techniques to be improved for containment building. In other words, a complete description of the standard degenerated shell finite element formulation is provided for nonlinear stress analysis of nuclear containment structure. A shell finite element is derived using the degenerated solid concept which does not rely on a specific shell theory. Reissner-Mindlin assumptions are adopted to consider the transverse shear deformation effect. In order to minimize the sensitivity of the constitutive equation to structural types, microscopic material model is adopted. The four solution algorithms based on the standard Newton-Raphson method are discussed. Finally, two numerical examples are carried out to test the performance of the adopted shell medel
New Ground-State Crystal Structure of Elemental Boron.
An, Qi; Reddy, K Madhav; Xie, Kelvin Y; Hemker, Kevin J; Goddard, William A
2016-08-19
Elemental boron exhibits many polymorphs in nature based mostly on an icosahedral shell motif, involving stabilization of 13 strong multicenter intraicosahedral bonds. It is commonly accepted that the most thermodynamic stable structure of elemental boron at atmospheric pressure is the β rhombohedral boron (β-B). Surprisingly, using high-resolution transmission electron microscopy, we found that pure boron powder contains grains of two different types, the previously identified β-B containing a number of randomly spaced twins and what appears to be a fully transformed twinlike structure. This fully transformed structure, denoted here as τ-B, is based on the Cmcm orthorhombic space group. Quantum mechanics predicts that the newly identified τ-B structure is 13.8 meV/B more stable than β-B. The τ-B structure allows 6% more charge transfer from B_{57} units to nearby B_{12} units, making the net charge 6% closer to the ideal expected from Wade's rules. Thus, we predict the τ-B structure to be the ground state structure for elemental boron at atmospheric pressure. PMID:27588864
Finite Element Vibration Analysis of Laminated Composite Folded Plate Structures
A. Guha Niyogi
1999-01-01
Full Text Available A nine-noded Lagrangian plate bending finite element that incorporates first-order transverse shear deformation and rotary inertia is used to predict the free and forced vibration response of laminated composite folded plate structures. A 6 × 6 transformation matrix is derived to transform the system element matrices before assembly. The usual five degrees-of-freedom per node is appended with an additional drilling degree of freedom in order to fit the transformation. The present finite element results show good agreement with the available semi-analytical solutions and finite element results. Parametric studies are conducted for free and forced vibration analysis for laminated folded plates, with reference to crank angle, fibre angle and stacking sequence. The natural frequencies and mode shapes, and forced vibration responses furnished here may serve as a benchmark for future investigations.
SOME ELEMENTS OF STRUCTURALISM AND ITS APPLICATION TO LITERARY THEORY
John LYE
2011-01-01
Structuralism is a mode of thinking and a method of analysis practiced in 20th century social sciences and humanities or it is a general approach in various academic disciplines. In this article John Lye has dealt with the subject of “Some Elements of Structuralism and its Application to Literary Theory”. Text has consisted of subtitles as “I-General Principles”, “II-Structuralism, Culture and Texts”, “III-Sturcturalism and Literature” and “IV-Structural Analysis”. Author has mentioned from...
Criteria for structural verification of fast reactor core elements
Structural and functional criteria and relative verifications of PEC reactor fuel element are presented and discussed. Particular attention has been given to differentiate the structural verifications of low neutronic damage zones from those high neutronic damage ones. The structural verification criteria, which had already been presented at the 8th SMIRT Seminar Conference in Paris, have had some modifications during the Safety Report preparation. Finally some necessary activities are indicated for structural criteria validation, in particular for irradiated components, and for converging towards a European fast reactor code. (author). 3 refs, 6 tabs
Picornavirus IRES elements: RNA structure and host protein interactions.
Martínez-Salas, Encarnación; Francisco-Velilla, Rosario; Fernandez-Chamorro, Javier; Lozano, Gloria; Diaz-Toledano, Rosa
2015-08-01
Internal ribosome entry site (IRES) elements were discovered in picornaviruses. These elements are cis-acting RNA sequences that adopt diverse three-dimensional structures and recruit the translation machinery using a 5' end-independent mechanism assisted by a subset of translation initiation factors and various RNA binding proteins termed IRES transacting factors (ITAFs). Many of these factors suffer important modifications during infection including cleavage by picornavirus proteases, changes in the phosphorylation level and/or redistribution of the protein from the nuclear to the cytoplasm compartment. Picornavirus IRES are amongst the most potent elements described so far. However, given their large diversity and complexity, the mechanistic basis of its mode of action is not yet fully understood. This review is focused to describe recent advances on the studies of RNA structure and RNA-protein interactions modulating picornavirus IRES activity. PMID:25617758
True Stress-True Strain Models for Structural Steel Elements
Arasaratnam, P.; K. S. Sivakumaran; Tait, M J
2011-01-01
A standard uniaxial tensile test, which establishes the engineering stress-strain relationship, in general, provides the basic mechanical properties of steel required by a structural designer. Modern numerical analysis techniques used for analysis of large strain problems such as failure analysis of steel structures and elements metal forming, metal cutting, and so forth, will require implementation and use of true stress-true strain material characterization. This paper establishes a five st...
Better Finite-Element Analysis of Composite Shell Structures
Clarke, Gregory
2007-01-01
A computer program implements a finite-element-based method of predicting the deformations of thin aerospace structures made of isotropic materials or anisotropic fiber-reinforced composite materials. The technique and corresponding software are applicable to thin shell structures in general and are particularly useful for analysis of thin beamlike members having open cross-sections (e.g. I-beams and C-channels) in which significant warping can occur.
Welding device for nuclear fuel assembly structure elements
The device has two parallel assembling positions next to each other. The welding robot is carried by a carriage with displacement parallel to the guide tubes and has enough degrees of freedom to move from one assembling position to the other and have access to the structural elements
2-D Finite Element Analysis of Massive RC Structures
Saabye Ottosen, Niels
1982-01-01
Nonlinear analysis of concrete structures using finite elements is discussed. The applications include a thick-walled top-closure for a pressure vessel as well as the delicate problems of beams failing in shear. The top-closure analysis evaluates the effect of two different failure criteria and...
2-D Finite Element Analysis of Massive RC Structures
Saabye Ottosen, Niels
1982-01-01
Nonlinear analysis of concrete structures using finite elements is discussed. The applications include a thick-walled top-closure for a pressure vessel as well as the delicate problems of beams failing in shear. The top-closure analysis evaluates the effect of two different failure criteria and m...
Variation of Mixed Hodge Structure and Primitive elements
Rahmati, Mohammad Reza
2014-01-01
We study the asymptotic behaviour of polarization form in the variation of mixed Hodge structure associated to isolated hypersurface singularities. The contribution characterizes a modification of Grothendieck residue as the polarization on the extended fiber in this case. We also provide a discussion on primitive elements to explain conjugation operator in these variations, already existed in the literature.
Finite element thermo-viscoplastic analysis of aerospace structures
Pandey, Ajay K.; Dechaumphai, Pramote; Thornton, Earl A.
1990-01-01
The time-dependent thermo-viscoplastic response of aerospace structures subjected to intense aerothermal loads is predicted using the finite-element method. The finite-element analysis uses the Bodner-Partom unified viscoplastic constitutive relations to determine rate-dependent nonlinear material behavior. The methodology is verified by comparison with experimental data and other numerical results for a uniaxially-loaded bar. The method is then used (1) to predict the structural response of a rectangular plate subjected to line heating along a centerline, and (2) to predict the thermal-structural response of a convectively-cooled engine cowl leading edge subjected to aerodynamic shock-shock interference heating. Compared to linear elastic analysis, the viscoplastic analysis results in lower peak stresses and regions of plastic deformations.
Finite-element thermo-viscoplastic analysis of aerospace structures
Pandey, Ajay; Dechaumphai, Pramote; Thornton, Earl A.
1990-01-01
The time-dependent thermo-viscoplastic response of aerospace structures subjected to intense aerothermal loads is predicted using the finite-element method. The finite-element analysis uses the Bodner-Partom unified viscoplastic constitutive relations to determine rate-dependent nonlinear material behavior. The methodology is verified by comparison with experimental data and other numerical results for a uniaxially-loaded bar. The method is then used (1) to predict the structural response of a rectangular plate subjected to line heating along a centerline, and (2) to predict the thermal-structural response of a convectively-cooled engine cowl leading edge subjected to aerodynamic shock-shock interference heating. Compared to linear elastic analysis, the viscoplastic analysis results in lower peak stresses and regions of plastic deformations.
Correlative Imaging of Structural and Elemental Composition of Bacterial Biofilms
Synchrotron-based phase contrast tomography (holotomography) and scanning hard X-ray fluorescence microscopy (SXFM) are combined to characterize the three-dimensional (3D) structural and corresponding elemental distribution of bacterial biofilms of Pseudomonas aeruginosa. Samples were fixed without contrast agents or microtomal sectioning. Within an intact microbial community single bacteria are clearly resolved, and their morphology can be directly visualized together with the elemental content. Such 3D set of complementary information at cellular level is essential for gaining a deeper understanding of biofilm evolution aiming to develop potential strategies on biofilm growth control and prevention
Correlative Imaging of Structural and Elemental Composition of Bacterial Biofilms
Yang, Y.; Heine, R.; Xu, F.; Suhonen, H.; Helfen, L.; Rosenhahn, A.; Gorniak, T.; Kirchen, S.; Schwartz, T.; Baumbach, T.
2013-10-01
Synchrotron-based phase contrast tomography (holotomography) and scanning hard X-ray fluorescence microscopy (SXFM) are combined to characterize the three-dimensional (3D) structural and corresponding elemental distribution of bacterial biofilms of Pseudomonas aeruginosa. Samples were fixed without contrast agents or microtomal sectioning. Within an intact microbial community single bacteria are clearly resolved, and their morphology can be directly visualized together with the elemental content. Such 3D set of complementary information at cellular level is essential for gaining a deeper understanding of biofilm evolution aiming to develop potential strategies on biofilm growth control and prevention.
Hypersensitive transition spectrum of f-element and coordination structure
Some f-f transitions of Ln(An) metallic ions have particular super-sensitivity to the change of coordination environments. This is called super-sensitive transitions. Based on the irreducible tensor operator method, a computation model and corresponding computer program for calculating the hypersensitive transition spectrum of f-element were developed. By comparing the theoretical spectra of all possible coordination structures with experimental one, the possible coordination structures of complex can be determined. The coordination structures of Nd3+, Er3+ hydrate and their extraction complex with H(DEHP) were successfully determined by this method, and the experimental spectra were also assigned
Engineering computation of structures the finite element method
Neto, Maria Augusta; Roseiro, Luis; Cirne, José; Leal, Rogério
2015-01-01
This book presents theories and the main useful techniques of the Finite Element Method (FEM), with an introduction to FEM and many case studies of its use in engineering practice. It supports engineers and students to solve primarily linear problems in mechanical engineering, with a main focus on static and dynamic structural problems. Readers of this text are encouraged to discover the proper relationship between theory and practice, within the finite element method: Practice without theory is blind, but theory without practice is sterile. Beginning with elasticity basic concepts and the classical theories of stressed materials, the work goes on to apply the relationship between forces, displacements, stresses and strains on the process of modeling, simulating and designing engineered technical systems. Chapters discuss the finite element equations for static, eigenvalue analysis, as well as transient analyses. Students and practitioners using commercial FEM software will find this book very helpful. It us...
Simplified Finite Element Modelling of Acoustically Treated Structures
Carfagni, M.; Citti, P.; Pierini, M.
1997-07-01
The application of non-optimized damping and phono-absorbent materials to automotive systems has not proved fully satisfactory in abating noise and vibration. The objective of this work was to develop a simple finite element modelling procedure that would allow optimizing structures such as a car body-in-white in terms of vibroacoustic behavior from the design stage. A procedure was developed to determine the modifications to be made in the mass, stiffness and damping characteristics in the finite element (FE) modelling of a metal structure meshed with shell elements so that the model would describe the behavior of the acoustically treated structure. To validate the modifications, a numerical-experimental comparison of the velocities on the vibrating surface was carried out, followed by a numerical-experimental comparison of the sound pressures generated by the vibrating plate. In the comparison a simple monopole model was used, in which each area of vibrating surface could be likened to a point source. The simulation and experimental procedures, previously validated for the metal structure, were then applied to multi-layered panels. Good agreement between the experimental and simulated velocities and sound pressures resulted for all the multi-layered panel configurations examined.
Finite Element Based HWB Centerbody Structural Optimization and Weight Prediction
Gern, Frank H.
2012-01-01
This paper describes a scalable structural model suitable for Hybrid Wing Body (HWB) centerbody analysis and optimization. The geometry of the centerbody and primary wing structure is based on a Vehicle Sketch Pad (VSP) surface model of the aircraft and a FLOPS compatible parameterization of the centerbody. Structural analysis, optimization, and weight calculation are based on a Nastran finite element model of the primary HWB structural components, featuring centerbody, mid section, and outboard wing. Different centerbody designs like single bay or multi-bay options are analyzed and weight calculations are compared to current FLOPS results. For proper structural sizing and weight estimation, internal pressure and maneuver flight loads are applied. Results are presented for aerodynamic loads, deformations, and centerbody weight.
A Curved, Elastostatic Boundary Element for Plane Anisotropic Structures
Smeltzer, Stanley S.; Klang, Eric C.
2001-01-01
The plane-stress equations of linear elasticity are used in conjunction with those of the boundary element method to develop a novel curved, quadratic boundary element applicable to structures composed of anisotropic materials in a state of plane stress or plane strain. The curved boundary element is developed to solve two-dimensional, elastostatic problems of arbitrary shape, connectivity, and material type. As a result of the anisotropy, complex variables are employed in the fundamental solution derivations for a concentrated unit-magnitude force in an infinite elastic anisotropic medium. Once known, the fundamental solutions are evaluated numerically by using the known displacement and traction boundary values in an integral formulation with Gaussian quadrature. All the integral equations of the boundary element method are evaluated using one of two methods: either regular Gaussian quadrature or a combination of regular and logarithmic Gaussian quadrature. The regular Gaussian quadrature is used to evaluate most of the integrals along the boundary, and the combined scheme is employed for integrals that are singular. Individual element contributions are assembled into the global matrices of the standard boundary element method, manipulated to form a system of linear equations, and the resulting system is solved. The interior displacements and stresses are found through a separate set of auxiliary equations that are derived using an Airy-type stress function in terms of complex variables. The capabilities and accuracy of this method are demonstrated for a laminated-composite plate with a central, elliptical cutout that is subjected to uniform tension along one of the straight edges of the plate. Comparison of the boundary element results for this problem with corresponding results from an analytical model show a difference of less than 1%.
Seybert, A. F.; Wu, T. W.; Wu, X. F.
1994-01-01
This research report is presented in three parts. In the first part, acoustical analyses were performed on modes of vibration of the housing of a transmission of a gear test rig developed by NASA. The modes of vibration of the transmission housing were measured using experimental modal analysis. The boundary element method (BEM) was used to calculate the sound pressure and sound intensity on the surface of the housing and the radiation efficiency of each mode. The radiation efficiency of each of the transmission housing modes was then compared to theoretical results for a finite baffled plate. In the second part, analytical and experimental validation of methods to predict structural vibration and radiated noise are presented. A rectangular box excited by a mechanical shaker was used as a vibrating structure. Combined finite element method (FEM) and boundary element method (BEM) models of the apparatus were used to predict the noise level radiated from the box. The FEM was used to predict the vibration, while the BEM was used to predict the sound intensity and total radiated sound power using surface vibration as the input data. Vibration predicted by the FEM model was validated by experimental modal analysis; noise predicted by the BEM was validated by measurements of sound intensity. Three types of results are presented for the total radiated sound power: sound power predicted by the BEM model using vibration data measured on the surface of the box; sound power predicted by the FEM/BEM model; and sound power measured by an acoustic intensity scan. In the third part, the structure used in part two was modified. A rib was attached to the top plate of the structure. The FEM and BEM were then used to predict structural vibration and radiated noise respectively. The predicted vibration and radiated noise were then validated through experimentation.
Influence of coolant motion on structure of hardened steel element
A. Kulawik
2008-08-01
Full Text Available Presented paper is focused on volumetric hardening process using liquid low melting point metal as a coolant. Effect of convective motion of the coolant on material structure after hardening is investigated. Comparison with results obtained for model neglecting motion of liquid is executed. Mathematical and numerical model based on Finite Element Metod is described. Characteristic Based Split (CBS method is used to uncouple velocities and pressure and finally to solve Navier-Stokes equation. Petrov-Galerkin formulation is employed to stabilize convective term in heat transport equation. Phase transformations model is created on the basis of Johnson-Mehl and Avrami laws. Continuous cooling diagram (CTPc for C45 steel is exploited in presented model of phase transformations. Temporary temperatures, phases participation, thermal and structural strains in hardening element and coolant velocities are shown and discussed.
Electoral structure of building foundations in nuclear fuel element plant
Plant structures of nuclear fuel elements have a substantial burden. This requires analysis of the selection of the proper foundation for building support for a variety of different soil conditions found in two locations, first at a location near the nuclear power plant in Jepara and the second location BATAN Serpong area. Expected to know the location of soil conditions, we can determined the type of foundation that will be used based on the criteria requirements of the building. (author)
Detection, placement and tracking loads on structural elements
Baeza de los Santos, Francisco Javier; Ivorra Chorro, Salvador; Zornoza Gómez, Emilio; García Andión, Luis
2010-01-01
Comunicación presentada en XXXVII IAHS World Congress on Housing, Santander, 26-29 Octubre 2010. This paper presents an analytical, numerical and experimental approach to detect, measure, locate and track moving loads in a structural element using discrete strain measures. An analytical model considering an Euler-Bernoulli beam was first studied in simple supported beam. Then a computer gorithm was implemented by using numerical models to automatically detect, locate and track different co...
Isogeometric Finite Element Code Development for Analysis of Composite Structures
Kapoor, Hitesh
2013-01-01
This research endeavor develops Isogeometric approach for analysis of composite structures and take advantage of higher order continuity, smoothness and variation diminishing property of Nurbs basis for stress analysis of composite and sandwich beams and plates. This research also computes stress concentration factor in a composite plate with a hole.Isogeometric nonlinear/linear finite element code is developed for static and dynamic analysis of laminated composite plates. Nurbs linear, quadr...
Mortar for covering structural elements, with high acustic performance levels
Sanchez de Rojas, M.I.; Olaya Adán, Manuel; Frías Rojas, Moisés; Olmeda, J.; Frutos Vázquez, Borja; Rivera Lozano, Julián; Esteban, J. Luis
2011-01-01
[EN] The incorporation of a covering mortar based on cement and granulated coke with particle diameters between 1 and 6 mm, into structural elements such as a brickwork extrados, gives a dual effect of enhanced acoustic insulation. This effect is due to the increase in the mass by the spraying of the mortar and to acoustic absorption as a consequence of the porous network of the material applied. The acoustic performance levels achieved exceed those of the same configuration as a double wall ...
Nonlinear Finite Element Analysis of the Structure of Door Seals
ZHAO Jian-cai; ZHU Xun-sheng; ZHOU Chi-xing
2005-01-01
In order to evaluate the influence of the seal structure on door closing force, nonlinear finite element method is introduced to analyze compression deformation of a door seal for SANTANA (name of the car made by Shanghai Volkswagen Co. Ltd). MSC. Marc software is used to analyze the large deformation of the seal and the compression test is done to prove the computational results. The results show that the compression loads of the door seal are larger than the standard value of Shanghai Volkswagen Co. Ltd and the seal structure needs to be optimized. There are consistent relationships between calculating results and experimental results and the simulation method is effective.
Thermomechanical finite element analysis of hot water boiler structure
Živković Dragoljub S.; Milčić Dragan S.; Banić Milan S.; Milosavljević Peđa M.
2012-01-01
The paper presents an application of the Finite Elements Method for stress and strain analysis of the hot water boiler structure. The aim of the research was to investigate the influence of the boiler scale on the thermal stresses and strains of the structure of hot water boilers. Results show that maximum thermal stresses appear in the zone of the pipe carrying wall of the first reversing chamber. This indicates that the most critical part of the boiler are weld spots of the smoke pipe...
RSW Mixed Element Cell-Centered Fine Mesh
National Aeronautics and Space Administration — This is a RSW mixed-element unstructured fine mesh for cell-centered solvers. UG3 : Grid File Name = rsw_fine_mixedcc.b8.ugrid UG3 : Quad Surface Faces= 28968 UG3 :...
A Discrete-Element Approach for Blood Cell Adhesion
Chesnutt, Jennifer; Marshall, Jeffrey
2006-11-01
An efficient computational model for simulation of the individual dynamics of adhering blood cells is discussed. Each cell is represented as a discrete particle so that the model can extend existing discrete-element approaches for dense particulate fluid flows to account for receptor-ligand binding of particles, elliptical particle shape, and deformation of the particles due to shear forces. Capabilities of the method in simulating large numbers of particles are illustrated through simulations of the formation of red blood cell rouleaux in shear flow. The effects of several factors, such as aspect ratio of the elliptical particle, shear rate, strength of the cell adhesion force, and hematocrit are investigated. Comparison of the discrete-element results with results of a level-set approach which computes the entire flow field about a small number of cells is used to develop an improved model of the effect of nearby red blood cells on the cell drag force expression. The method is also being applied to examine the influence of red blood cells on other components of the blood, such as platelet dispersion and activation in high shear regions.
Cell-Sediment Separation and Elemental Stoichiometries in Extreme Environments
Neveu, M.; Poret-peterson, A. T.; Lee, Z. M.; Anbar, A. D.; Elser, J. J.
2012-12-01
Better understanding of the coupling of major biogeochemical cycles requires knowledge of the cellular elemental composition of key microbes. This is difficult in benthic sediments and mats, because of the contributions of non-living components. We are particularly interested in microbial extremophiles, and therefore sought to determine and interpret bulk and cellular elemental ratios in complex field-collected sediment samples from diverse hot spring ecosystems of Yellowstone National Park (YNP). These samples covered a broad range of temperature, pH, and chemical composition. We also sought to extend stoichiometric analysis to a broader suite of elements, including metals (Fe, Ni, Cu, Zn, Mo, etc.) of biological importance (Sterner and Elser, 2002). To overcome the challenge of rigorously isolating communities from their complex mineral matrices (Havig et al., 2011), we adapted a cell-sediment separation procedure from Amalfitano and Fazi (2008). The method involves chemical (use of a detergent and a chelating agent) and physical methods (stirring, gentle sonication, and gradient centrifugation) to break the microbe-mineral bonds. C and N elemental and isotopic abundances were determined by elemental analysis - isotope ratio - mass spectrometry (EA-IR-MS), while P, Na, Mg, Al, K, Ca, V, Cr, Fe, Co, Ni, Cu, Zn, and Mo contents were determined by inductively coupled plasma - mass spectrometry (ICP-MS). We sought to assess the existence of an "Extended Redfield Ratio" (ERR) for these microbes; that is, to establish the multi-element stoichiometric envelope within which extremophilic microbes must operate. Elemental and isotopic mass balance analyses of cultured E. coli before and after separation showed that our procedure preserved cellular C, N, P, Fe, and trace metal contents: neither loss of these elements (e.g., by cell lysis) nor contamination by reagents were observed. On the other hand, cation-forming elements (Na, Mg, K, Ca), were not conserved. Cell
Contents of selected elements in the mineral structure of gallstones
Kwapuliński Jerzy
2014-06-01
Full Text Available Introduction. In this work, the problem of occurrence and co-occurrence of titanium, lithium, molybdenum, strontium, calcium, magnesium, sodium and potassium in the choleliths of the inhabitants of Częstochowa and Bielsko-Biała district has been presented. The choice of research area was determined by the different mineral structure of suspended dust in the air, as well as the average different occurrence of some other minerals in suspended dust in the air. The aim of the studies was to define the level of accumulation and coincidention of Ti, Li, Mo, Sr, Ca, Mg, Na, K in deposits in the gallbladder. Materials and methods. The content of these particular elements in the gall bladder deposits obtained during cholecystectomy was assessed by means of inductive coupled plasma – atomic emission spectrometry (ICP – AES with accuracy to 0,01 µg/g. Results. The presence of selected elements in the mineral structure of gall bladder deposits is illustrated by the vast statistical characteristic of their occurrence in the inhabitants of Częstochowa and Bielsko-Biała district. This is also documented by the course of quotient changes of the individual element’s content, compared to their sum in the function of changes of their average content in the gall bladder deposits. Conclusions. The level of examined elements in gallbladder deposits was different according to place of living and gender, those differences being better discriminated by geometrical averages.
Automated identification of elemental ions in macromolecular crystal structures
The solvent-picking procedure in phenix.refine has been extended and combined with Phaser anomalous substructure completion and analysis of coordination geometry to identify and place elemental ions. Many macromolecular model-building and refinement programs can automatically place solvent atoms in electron density at moderate-to-high resolution. This process frequently builds water molecules in place of elemental ions, the identification of which must be performed manually. The solvent-picking algorithms in phenix.refine have been extended to build common ions based on an analysis of the chemical environment as well as physical properties such as occupancy, B factor and anomalous scattering. The method is most effective for heavier elements such as calcium and zinc, for which a majority of sites can be placed with few false positives in a diverse test set of structures. At atomic resolution, it is observed that it can also be possible to identify tightly bound sodium and magnesium ions. A number of challenges that contribute to the difficulty of completely automating the process of structure completion are discussed
Micro-Computed Tomography and Finite Element Method Study of Open-Cell Porous Materials
Wejrzanowski Tomasz; Skibinski Jakub; Cwieka Karol; Kurzydlowski Krzysztof J.
2015-01-01
In the present paper the characterization of structure and properties of open-cell porous materials by high-resolution x-ray micro-computed tomography (μCT) and finite element method (FEM) is addressed. The unique properties of open porosity foams make them interesting in a range of applications in science and engineering such as energy absorbers, lightweight construction materials or heat insulators. Consequently, a detailed knowledge of structure as well as mechanical properties (i.e. Young...
Elasto-viscoplastic finite element model for prestressed concrete structures
This paper presents a computational model, based on the finite element method, for the study of reinforced and prestressed concrete structures under plane stress states. It comprehends short and long-term loading situations, where creep and shrinkage in concrete and steel relaxation are considered. Elasto-viscoplastic constitutive models are used to describe the behavior of the materials. The model includes prestressing and no prestressing reinforcement, on situation with pre- and post-tension with and without bond. A set of prestressed concrete slab elements were tested under instantaneous and long-term loading. The experimental data for deflections, deformations and ultimate strength are used to compare and validate the results obtained through the proposed model. (author). 11 refs., 5 figs
Mass spectrometric characterization of elements and molecules in cell cultures and tissues
Arlinghaus, H. F.; Kriegeskotte, C.; Fartmann, M.; Wittig, A.; Sauerwein, W.; Lipinsky, D.
2006-07-01
Time-of-flight secondary ion mass spectrometry (ToF-SIMS) and laser post-ionization secondary neutral mass spectrometry (laser-SNMS) have been used to image and quantify targeted compounds, intrinsic elements and molecules with subcellular resolution in single cells of both cell cultures and tissues. Special preparation procedures for analyzing cell cultures and tissue materials were developed. Cancer cells type MeWo, incubated with boronated compounds, were sandwiched between two substrates, cryofixed, freeze-fractured and freeze-dried. Also, after injection with boronated compounds, different types of mouse tissues were extracted, prepared on a special specimen carrier and plunged with high velocity into LN 2-cooled propane for cryofixation. After trimming, these tissue blocks were freeze-dried. The measurements of the K/Na ratio demonstrated that for both cell cultures and tissue materials the special preparation techniques used were appropriate for preserving the chemical and structural integrity of the living cell. The boron images show inter- and intracellular boron signals with different intensities. Molecular images show distinct features partly correlated with the cell structure. A comparison between laser-SNMS and ToF-SIMS showed that especially laser-SNMS is particularly well-suited for identifying specific cell structures and imaging ultratrace element concentrations in tissues.
Mass spectrometric characterization of elements and molecules in cell cultures and tissues
Arlinghaus, H.F. [Physikalisches Institut, Universitaet Muenster, Wilhelm-Klemm-Str. 10, D-48149 Muenster (Germany)]. E-mail: arlinghaus@uni-muenster.de; Kriegeskotte, C. [Physikalisches Institut, Universitaet Muenster, Wilhelm-Klemm-Str. 10, D-48149 Muenster (Germany); Fartmann, M. [Physikalisches Institut, Universitaet Muenster, Wilhelm-Klemm-Str. 10, D-48149 Muenster (Germany); Wittig, A. [Strahlenklinik, Universitaetsklinikum Essen, D-45122 Essen (Germany); Sauerwein, W. [Strahlenklinik, Universitaetsklinikum Essen, D-45122 Essen (Germany); Lipinsky, D. [Physikalisches Institut, Universitaet Muenster, Wilhelm-Klemm-Str. 10, D-48149 Muenster (Germany)
2006-07-30
Time-of-flight secondary ion mass spectrometry (ToF-SIMS) and laser post-ionization secondary neutral mass spectrometry (laser-SNMS) have been used to image and quantify targeted compounds, intrinsic elements and molecules with subcellular resolution in single cells of both cell cultures and tissues. Special preparation procedures for analyzing cell cultures and tissue materials were developed. Cancer cells type MeWo, incubated with boronated compounds, were sandwiched between two substrates, cryofixed, freeze-fractured and freeze-dried. Also, after injection with boronated compounds, different types of mouse tissues were extracted, prepared on a special specimen carrier and plunged with high velocity into LN{sub 2}-cooled propane for cryofixation. After trimming, these tissue blocks were freeze-dried. The measurements of the K/Na ratio demonstrated that for both cell cultures and tissue materials the special preparation techniques used were appropriate for preserving the chemical and structural integrity of the living cell. The boron images show inter- and intracellular boron signals with different intensities. Molecular images show distinct features partly correlated with the cell structure. A comparison between laser-SNMS and ToF-SIMS showed that especially laser-SNMS is particularly well-suited for identifying specific cell structures and imaging ultratrace element concentrations in tissues.
Seybert, A. F.; Wu, X. F.; Oswald, Fred B.
1992-01-01
Analytical and experimental validation of methods to predict structural vibration and radiated noise are presented. A rectangular box excited by a mechanical shaker was used as a vibrating structure. Combined finite element method (FEM) and boundary element method (BEM) models of the apparatus were used to predict the noise radiated from the box. The FEM was used to predict the vibration, and the surface vibration was used as input to the BEM to predict the sound intensity and sound power. Vibration predicted by the FEM model was validated by experimental modal analysis. Noise predicted by the BEM was validated by sound intensity measurements. Three types of results are presented for the total radiated sound power: (1) sound power predicted by the BEM modeling using vibration data measured on the surface of the box; (2) sound power predicted by the FEM/BEM model; and (3) sound power measured by a sound intensity scan. The sound power predicted from the BEM model using measured vibration data yields an excellent prediction of radiated noise. The sound power predicted by the combined FEM/BEM model also gives a good prediction of radiated noise except for a shift of the natural frequencies that are due to limitations in the FEM model.
Extended Finite Element Method for Fracture Analysis of Structures
Mohammadi, Soheil
2008-01-01
This important textbook provides an introduction to the concepts of the newly developed extended finite element method (XFEM) for fracture analysis of structures, as well as for other related engineering applications.One of the main advantages of the method is that it avoids any need for remeshing or geometric crack modelling in numerical simulation, while generating discontinuous fields along a crack and around its tip. The second major advantage of the method is that by a small increase in number of degrees of freedom, far more accurate solutions can be obtained. The method has recently been
The Distinct Element Method - Application to Structures in Jointed Rock
Morris, J.P.; Glen, L.; Blair, S.; Heuze, F.
2001-11-30
The Distinct Element Method (DEM) is a meshfree method with applications to rock mechanics, mining sciences, simulations of nuclear repositories, and the stability of underground structures. Continuum mesh-based methods have been applied successfully to many problems in geophysics. Even if the geology includes fractures and faults, when sufficiently large length scales are considered a continuum approximation may be sufficient. However, a large class of problems exist where individual rock joints must be taken into account. This includes problems where the structures of interest have sizes comparable with the block size. In addition, it is possible that while the structure may experience loads which do no measurable damage to individual blocks, some joints may fail. This may launch smaller blocks as dangerous projectiles or even cause total failure of a tunnel. Traditional grid-based continuum approaches are wholly unsuited to this class of problem. It is possible to introduce discontinuities or slide lines into existing grid-based methods, however, such limited approaches can break down when new contacts form between blocks. The distinct element method (DEM) is an alternative, meshfree approach. The DEM can directly approximate the block structure of the jointed rock using arbitrary polyhedra. Using this approach, preexisting joints are readily incorporated into the DEM model. In addition, the method detects all new contacts between blocks resulting from relative block motion. We will describe the background of the DEM and review previous application of the DEM to geophysical problems. Finally we present preliminary results from a investigation into the stability of underground structures subjected to dynamic loading.
Finite element assessment of precast concrete slab using ANSYS structural
Concrete is used widely in all types of construction. In particular, it is the first choice material for the construction of various industries, due to its affordability, durability, heat resistance, strength, etc. Based on this, understanding the response of concrete structural components for all types of loading is crucial to the development of an overall safe and efficient structure. Various methods have been used to study the response of concrete structural components to various loading regimes. Experimental based testing has been widely used as a means to analyse individual components; this method is, however, extremely time consuming and can be quite costly. Presently, the use of finite element analysis has increased due to increasing knowledge and capabilities of computer software and hardware. It has now become the best method to analyse concrete structural components. In this study, a locally available precast concrete slab, termed the Trasaaco Fast Floor System, that is both reinforced and pre-stressed is analysed for its nonlinear behaviour under external imposed vertical loading conditions using the finite element (FE) method. The FE commercial software ANSYS 13.0, is used for the analysis. Load-deflection responses and the crack patterns at critical stages of loading are studied. The results from the ANSYS programme are compared with technical data obtained from the Trasacco Group. The comparison shows the ANSYS programme to satisfactorily predict the behavioural responses of the fast floor slab system up to failure. In addition, the results obtained confirm the fact that Trasaaco Fast Floor System can be potentially used to support the required loading regime for heavy industrial structures, like nuclear power plant facilities.
Real-time transposable element activity in individual live cells.
Kim, Neil H; Lee, Gloria; Sherer, Nicholas A; Martini, K Michael; Goldenfeld, Nigel; Kuhlman, Thomas E
2016-06-28
The excision and reintegration of transposable elements (TEs) restructure their host genomes, generating cellular diversity involved in evolution, development, and the etiology of human diseases. Our current knowledge of TE behavior primarily results from bulk techniques that generate time and cell ensemble averages, but cannot capture cell-to-cell variation or local environmental and temporal variability. We have developed an experimental system based on the bacterial TE IS608 that uses fluorescent reporters to directly observe single TE excision events in individual cells in real time. We find that TE activity depends upon the TE's orientation in the genome and the amount of transposase protein in the cell. We also find that TE activity is highly variable throughout the lifetime of the cell. Upon entering stationary phase, TE activity increases in cells hereditarily predisposed to TE activity. These direct observations demonstrate that real-time live-cell imaging of evolution at the molecular and individual event level is a powerful tool for the exploration of genome plasticity in stressed cells. PMID:27298350
Real-time transposable element activity in individual live cells
Lee, Gloria; Martini, K. Michael
2016-01-01
The excision and reintegration of transposable elements (TEs) restructure their host genomes, generating cellular diversity involved in evolution, development, and the etiology of human diseases. Our current knowledge of TE behavior primarily results from bulk techniques that generate time and cell ensemble averages, but cannot capture cell-to-cell variation or local environmental and temporal variability. We have developed an experimental system based on the bacterial TE IS608 that uses fluorescent reporters to directly observe single TE excision events in individual cells in real time. We find that TE activity depends upon the TE’s orientation in the genome and the amount of transposase protein in the cell. We also find that TE activity is highly variable throughout the lifetime of the cell. Upon entering stationary phase, TE activity increases in cells hereditarily predisposed to TE activity. These direct observations demonstrate that real-time live-cell imaging of evolution at the molecular and individual event level is a powerful tool for the exploration of genome plasticity in stressed cells. PMID:27298350
Live imaging of companion cells and sieve elements in Arabidopsis leaves.
Thibaud Cayla
Full Text Available The phloem is a complex tissue composed of highly specialized cells with unique subcellular structures and a compact organization that is challenging to study in vivo at cellular resolution. We used confocal scanning laser microscopy and subcellular fluorescent markers in companion cells and sieve elements, for live imaging of the phloem in Arabidopsis leaves. This approach provided a simple framework for identifying phloem cell types unambiguously. It highlighted the compactness of the meshed network of organelles within companion cells. By contrast, within the sieve elements, unknown bodies were observed in association with the PP2-A1:GFP, GFP:RTM1 and RTM2:GFP markers at the cell periphery. The phloem lectin PP2-A1:GFP marker was found in the parietal ground matrix. Its location differed from that of the P-protein filaments, which were visualized with SEOR1:GFP and SEOR2:GFP. PP2-A1:GFP surrounded two types of bodies, one of which was identified as mitochondria. This location suggested that it was embedded within the sieve element clamps, specific structures that may fix the organelles to each another or to the plasma membrane in the sieve tubes. GFP:RTM1 was associated with a class of larger bodies, potentially corresponding to plastids. PP2-A1:GFP was soluble in the cytosol of immature sieve elements. The changes in its subcellular localization during differentiation provide an in vivo blueprint for monitoring this process. The subcellular features obtained with these companion cell and sieve element markers can be used as landmarks for exploring the organization and dynamics of phloem cells in vivo.
A new program for calculating matrix elements in atomic structure
The solution of many problems concerning the electronic structure of atoms requires the evaluation of the matrix elements of the Hamiltonian operator, including the electrostatic interaction. These matrix elements may be expressed as weighted sums of radial integrals. The program we describe in this paper evaluates the coefficients of the Slater integrals and, if these are given, computes all the matrix elements for a given set of configurations. This program has nearly the same purposes as Hibbert's program and is also based on the Racach techniques. The main difference between this algorithm and the cited one is the method used to calculate the recoupling coefficients. While Hibbert's programs use Burke's algorithm to calculate these coefficients, in our program they are computed using the graphical techniques developed by Jucys et al. According to this method, that we describe in another paper the formulae needed to calculate the recoupling coefficients are previously derived and simplified (as a first step of the program). The use of this method may considerably reduce the running time, specially in the case of large configuration interaction matrices. (orig.)
Finite element analysis of microelectrotension of cell membranes
Bae, Chilman; Butler, Peter J.
2007-01-01
Electric fields can be focused by micropipette-based electrodes to induce stresses on cell membranes leading to tension and poration. To date, however, these membrane stress distributions have not been quantified. In this study, we determine membrane tension, stress, and strain distributions in the vicinity of a microelectrode using finite element analysis of a multiscale electro-mechanical model of pipette, media, membrane, actin cortex, and cytoplasm. Electric field forces are coupled to me...
Meier, D L
1999-01-01
A new field of numerical astrophysics is introduced which addresses the solution of large, multidimensional structural or slowly-evolving problems (rotating stars, interacting binaries, thick advective accretion disks, four dimensional spacetimes, etc.). The technique employed is the Finite Element Method (FEM), commonly used to solve engineering structural problems. The approach developed herein has the following key features: 1. The computational mesh can extend into the time dimension, as well as space, perhaps only a few cells, or throughout spacetime. 2. Virtually all equations describing the astrophysics of continuous media, including the field equations, can be written in a compact form similar to that routinely solved by most engineering finite element codes. 3. The transformations that occur naturally in the four-dimensional FEM possess both coordinate and boost features, such that (a) although the computational mesh may have a complex, non-analytic, curvilinear structure, the physical equations stil...
Finite Element Analysis of Wrinkled Membrane Structures for Sunshield Applications
Johnston, John D.; Brodeur, Stephen J. (Technical Monitor)
2002-01-01
The deployable sunshield is an example of a gossamer structure envisioned for use on future space telescopes. The basic structure consists of multiple layers of pretensioned, thin-film membranes supported by deployable booms. The prediction and verification of sunshield dynamics has been identified as an area in need of technology development due to the difficulties inherent in predicting nonlinear structural behavior of the membranes and because of the challenges involved. in ground testing of the full-scale structure. This paper describes a finite element analysis of a subscale sunshield that has been subjected to ground testing in support of the Next Generation Space Telescope (NGST) program. The analysis utilizes a nonlinear material model that accounts for wrinkling of the membranes. Results are presented from a nonlinear static preloading analysis and subsequent dynamics analyses to illustrate baseline sunshield structural characteristics. Studies are then described which provide further insight into the effect of membrane. preload on sunshield dynamics and the performance of different membrane modeling techniques. Lastly, a comparison of analytical predictions and ground test results is presented.
A finite element model for nonlinear structural earthquake analysis
Towards the analysis of damage in reinforced concrete structures subjected to earthquakes, we propose a numerical model capable of describing the non-linear behaviour of reinforced concrete beams and columns under alternate cyclic loading, which can be efficiently used also in dynamic analysis: with the assumption of a local uniaxial state of stress, we are able to obtain the rapidity needed for the time integration of the dynamic equations of equilibrium for real structures, within a time interval corresponding to a seismic action. The model is presented: path-dependant constitutive material law and finite element formulation. An short example of validation serves to evaluate some characteristics of the model. A methodology is then developed to extend the applicability of the model for limit cases, regarding slenderness and semi-rigid limit conditions. (author)
Finite element analysis of loaded structures at very high temperatures
Breitbach, G.
1989-05-01
At very high temperatures loaded metallic structures undergo creep deformations. The generated creep strains are connected with stress relaxations, stress redistributions and/or progressive deformations. In mainly load controlled situations the behaviour of the material can be described by a non-linear viscous flow law (Norton power play). A stress-deformation analysis of complex structures can be carried out by finite element codes in which the mentioned constitutive equation is implemented. The code PERMAS-VISCOUS was used to analyse the stress state of a notched tension bar and the deformation behaviour of a reformer tube of HTR under external pressure undergoing a creep collapse. The relation to experimental findings is also given. (orig./HP).
Finite element analysis of loaded structures at very high temperatures
At very high temperatures loaded metallic structures undergo creep deformations. The generated creep strains are connected with stress relaxations, stress redistributions and/or progressive deformations. In mainly load controlled situations the behaviour of the material can be described by a non-linear viscous flow law (Norton power play). A stress-deformation analysis of complex structures can be carried out by finite element codes in which the mentioned constitutive equation is implemented. The code PERMAS-VISCOUS was used to analyse the stress state of a notched tension bar and the deformation behaviour of a reformer tube of HTR under external pressure undergoing a creep collapse. The relation to experimental findings is also given. (orig./HP)
Thermomechanical finite element analysis of hot water boiler structure
Živković Dragoljub S.
2012-01-01
Full Text Available The paper presents an application of the Finite Elements Method for stress and strain analysis of the hot water boiler structure. The aim of the research was to investigate the influence of the boiler scale on the thermal stresses and strains of the structure of hot water boilers. Results show that maximum thermal stresses appear in the zone of the pipe carrying wall of the first reversing chamber. This indicates that the most critical part of the boiler are weld spots of the smoke pipes and pipe carrying plate, which in the case of significant scale deposits can lead to cracks in the welds and water leakage from the boiler. The nonlinear effects were taken into account by defining the bilinear isotropic hardening model for all boiler elements. Temperature dependency was defined for all relevant material properties, i. e. isotropic coefficient of thermal expansion, Young’s modulus, and isotropic thermal conductivity. The verification of the FEA model was performed by comparing the measured deformations of the hot water boiler with the simulation results. As a reference object, a Viessmann - Vitomax 200 HW boiler was used, with the installed power of 18.2 MW. CAD modeling was done within the Autodesk Inventor, and stress and strain analysis was performed in the ANSYS Software.
Corrugated Membrane Fuel Cell Structures
Grot, Stephen [President, Ion Power Inc.
2013-09-30
One of the most challenging aspects of traditional PEM fuel cell stacks is the difficulty achieving the platinum catalyst utilization target of 0.2 gPt/kWe set forth by the DOE. Good catalyst utilization can be achieved with state-of-the-art catalyst coated membranes (CCM) when low catalyst loadings (<0.3 mg/cm2) are used at a low current. However, when low platinum loadings are used, the peak power density is lower than conventional loadings, requiring a larger total active area and a larger bipolar plate. This results in a lower overall stack power density not meeting the DOE target. By corrugating the fuel cell membrane electrode structure, Ion Power?s goal is to realize both the Pt utilization targets as well as the power density targets of the DOE. This will be achieved by demonstrating a fuel cell single cell (50 cm2) with a twofold increase in the membrane active area over the geometric area of the cell by corrugating the MEA structure. The corrugating structure must be able to demonstrate the target properties of < 10 mOhm-cm2 electrical resistance at > 20 psi compressive strength over the active area, in combination with offering at least 80% of power density that can be achieved by using the same MEA in a flat plate structure. Corrugated membrane fuel cell structures also have the potential to meet DOE power density targets by essentially packaging more membrane area into the same fuel cell volume as compared to conventional stack constructions.
Repetitive elements dynamics in cell identity programming, maintenance and disease
Bodega, Beatrice
2014-12-01
The days of \\'junk DNA\\' seem to be over. The rapid progress of genomics technologies has been unveiling unexpected mechanisms by which repetitive DNA and in particular transposable elements (TEs) have evolved, becoming key issues in understanding genome structure and function. Indeed, rather than \\'parasites\\', recent findings strongly suggest that TEs may have a positive function by contributing to tissue specific transcriptional programs, in particular as enhancer-like elements and/or modules for regulation of higher order chromatin structure. Further, it appears that during development and aging genomes experience several waves of TEs activation, and this contributes to individual genome shaping during lifetime. Interestingly, TEs activity is major target of epigenomic regulation. These findings are shedding new light on the genome-phenotype relationship and set the premises to help to explain complex disease manifestation, as consequence of TEs activity deregulation.
Modeling cell-in-cell structure into its biological significance
He, M-f; Wang, S.; Y Wang; Wang, X-n
2013-01-01
Although cell-in-cell structure was noted 100 years ago, the molecular mechanisms of ‘entering' and the destination of cell-in-cell remain largely unclear. It takes place among the same type of cells (homotypic cell-in-cell) or different types of cells (heterotypic cell-in-cell). Cell-in-cell formation affects both effector cells and their host cells in multiple aspects, while cell-in-cell death is under more intensive investigation. Given that cell-in-cell has an important role in maintainin...
Hurshkainen, Anna A.; Derzhavskaya, Tatyana A.; Glybovski, Stanislav B.; Voogt, Ingmar J.; Melchakova, Irina V.; van den Berg, Cornelis A. T.; Raaijmakers, Alexander J. E.
2016-08-01
Metasurfaces are artificial electromagnetic boundaries or interfaces usually implemented as two-dimensional periodic structures with subwavelength periodicity and engineered properties of constituent unit cells. The electromagnetic bandgap (EBG) effect in metasurfaces prevents all surface modes from propagating in a certain frequency band. While metasurfaces provide a number of important applications in microwave antennas and antenna arrays, their features are also highly suitable for MRI applications. In this work we perform a proof-of-principle experiment to study finite structures based on mushroom-type EBG metasurfaces and employ them for suppression of inter-element coupling in dipole transceive array coils for body imaging at 7 T. We firstly show experimentally that employment of mushroom structures leads to reduction of coupling between adjacent closely-spaced dipole antenna elements of a 7 T transceive body array, which reduces scattering losses in neighboring channels. The studied setup consists of two active fractionated dipole antennas previously designed by the authors for body imaging at 7 T. These are placed on top of a body-mimicking phantom and equipped with the manufactured finite-size periodic structure tuned to have EBG properties at the Larmor frequency of 298 MHz. To improve the detection range of the B1 + field distribution of the top elements, four additional elements were positioned along the bottom side of the phantom. Bench measurements of a scattering matrix showed that coupling between the two top elements can be considerably reduced depending on the distance to the EBG structure. On the other hand, the measurements performed on a 7 T MRI machine indicated redistribution of the B1 + field due to interaction between the dipoles with the structure. When the structure is located just over two closely spaced dipoles, one can reach a very high isolation improvement of -14 dB accompanied by a strong field redistribution. In contrast, when put
Seismic analysis of rectangular liquid storage structure is performed by using a coupled boundary element-finite method. The method models the liquid motion as the irrotation motion of ideal fluid by boundary element method. Coupling with finite element method for the containing structure is performed by using compatibility and equilibrium conditions along the interface of the fluid and structure interaction system such as sloshing motion, hydrodynamic pressure, displacement, effect of submerged objects are investigated and compared between two-and three-dimensional analysis results. (author). 6 refs., 12 figs
Metallographic examination of irradiated nuclear fuel elements at Radiometallurgy Hot Cell Facility
Radiometallurgy Hot Cells at the Bhabha Atomic Research Centre, Bombay, are fully equipped to carry out detailed metallographic examination of irradiated fuel elements. Procedures have been standardi.sed for the various steps needed in the preparation of samples suitable for metallographic observation. Existing facilities afford estimation of various parameters, like grain size and other structural changes in fuel and cladding materials, corrosion aspects and the various types of hydride formation in zircaloy clad, pellet clad interaction between fuel and clad which will help in assessing the actual behaviour of fuel elements during operation. (author)
Electronic structure and chemistry of the heaviest elements
Progress in the development of relativistic molecular codes has allowed for an adequate description of the electronic structure of the very heavy element compounds, and for the interpretation and prediction of their molecular properties. Most of the theoretical investigations for compounds, interesting from the experimental point of view, have been carried out using the LDF methods. The studied species were group 4, 5 and 6 gas-phase compounds of the transactinides along with their lighter homologs, and their complexes in aqueous solutions. As a result of these calculations, trends within the transition-element groups and within the beginning of the transactinide series for molecular properties such as ionicity, covalence, stability towards oxidation or reduction, crystal-field and spin-orbit effects, bonding, and the influence of relativistic effects on them have been established. In combination with some other models, these calculations allowed for predicting properties measured experimentally: volatility of compounds, redox potentials in solutions and complex formation. Especially promising were predictions of equilibria of reaction using the DS-DV method. Agreement between results of the calculations and experiment confirmed the necessity of doing relativistic MO calculations and the unreliability of the straightforward extrapolations of properties within the chemical groups. (orig.)
Electronic structure and chemistry of the heaviest elements
Pershina, V. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Fricke, B. [Kassel Univ. (Gesamthochschule) (Germany)
1998-04-01
Progress in the development of relativistic molecular codes has allowed for an adequate description of the electronic structure of the very heavy element compounds, and for the interpretation and prediction of their molecular properties. Most of the theoretical investigations for compounds, interesting from the experimental point of view, have been carried out using the LDF methods. The studied species were group 4, 5 and 6 gas-phase compounds of the transactinides along with their lighter homologs, and their complexes in aqueous solutions. As a result of these calculations, trends within the transition-element groups and within the beginning of the transactinide series for molecular properties such as ionicity, covalence, stability towards oxidation or reduction, crystal-field and spin-orbit effects, bonding, and the influence of relativistic effects on them have been established. In combination with some other models, these calculations allowed for predicting properties measured experimentally: volatility of compounds, redox potentials in solutions and complex formation. Especially promising were predictions of equilibria of reaction using the DS-DV method. Agreement between results of the calculations and experiment confirmed the necessity of doing relativistic MO calculations and the unreliability of the straightforward extrapolations of properties within the chemical groups. (orig.)
Edge Detection in Multispectral Images Based on Structural Elements
Mehdi Ghasemi Naraghi
2011-02-01
Full Text Available One of the first steps of feature extraction is edge detection. There are various methods for edge detection such as sobel operator, log method and canny operator. These methods have disadvantages such as create noise and discontinues edge and image smoothing. With the notice of the daily growth multi spectral images processing and describe of these images have become very important. Because of the existence of many details of these images, necessity to robust algorithms caused to present a method to extract featureof an object. In this article An improve method for edge detection has been purposed. In this method edge is detected by morphology’s operator and their combination and with the use of various structure elements of images in satellite and remote sensing.
Structure of nuclear transition matrix elements for neutrinoless double- decay
P K Rath
2010-08-01
The structure of nuclear transition matrix elements (NTMEs) required for the study of neutrinoless double- decay within light Majorana neutrino mass mechanism is disassembled in the PHFB model. The NTMEs are calculated using a set of HFB intrinsic wave functions, the reliability of which has been previously established by obtaining an overall agreement between the theoretically calculated spectroscopic properties and the available experimental data. Presently, we study the role of short-range correlations, radial evolution of NTMEs and deformation effects due to quadrupolar correlations. In addition, limits on effective light neutrino mass $\\langle m_{} \\rangle$ are extracted from the observed limits on half-lives $T_{1/2}^{0}$ of neutrinoless double- decay.
Aerial measurements of convection cell elements in heated lakes
Villa-Aleman, E.; Salaymeh, S. R.; Brown, T. B.; Garrett, A. J.; Nichols, L. S.; Pendergast, M. M.
2008-03-01
Power plant-heated lakes are characterized by a temperature gradient in the thermal plume originating at the discharge of the power plant and terminating at the water intake. The maximum water temperature discharged by the power plant into the lake depends on the power generated at the facility and environmental regulations on the temperature of the lake. Besides the observed thermal plume, cloud-like thermal cells (convection cell elements) are also observed on the water surface. The size, shape and temperature of the convection cell elements depends on several parameters such as the lake water temperature, wind speed, surfactants and the depth of the thermocline. The Savannah River National Laboratory (SRNL) and Clemson University are collaborating to determine the applicability of laboratory empirical correlations between surface heat flux and thermal convection intensity. Laboratory experiments at Clemson University have demonstrated a simple relationship between the surface heat flux and the standard deviation of temperature fluctuations. Similar results were observed in the aerial thermal imagery SRNL collected at different locations along the thermal plume and at different elevations. SRNL will present evidence that the results at Clemson University are applicable to cooling lakes.
Nature of the elements transporting long-chain fatty acids through the red cell membrane
Bojesen, Inge Norby; Bojesen, Eigil
1998-01-01
Docosahexaenoic acid, linoleic acid, red cell membrane, transporting elements, transport kinetics, fatty acid transport......Docosahexaenoic acid, linoleic acid, red cell membrane, transporting elements, transport kinetics, fatty acid transport...
Protein structure prediction: assembly of secondary structure elements by basin-hopping.
Hoffmann, Falk; Vancea, Ioan; Kamat, Sanjay G; Strodel, Birgit
2014-10-20
The prediction of protein tertiary structure from primary structure remains a challenging task. One possible approach to this problem is the application of basin-hopping global optimization combined with an all-atom force field. In this work, the efficiency of basin-hopping is improved by introducing an approach that derives tertiary structures from the secondary structure assignments of individual residues. This approach is termed secondary-to-tertiary basin-hopping and benchmarked for three miniproteins: trpzip, trp-cage and ER-10. For each of the three miniproteins, the secondary-to-tertiary basin-hopping approach successfully and reliably predicts their three-dimensional structure. When it is applied to larger proteins, correctly folded structures are obtained. It can be concluded that the assembly of secondary structure elements using basin-hopping is a promising tool for de novo protein structure prediction. PMID:25056272
Future Launch Vehicle Structures - Expendable and Reusable Elements
Obersteiner, M. H.; Borriello, G.
2002-01-01
Further evolution of existing expendable launch vehicles will be an obvious element influencing the future of space transportation. Besides this reusability might be the change with highest potential for essential improvement. The expected cost reduction and finally contributing to this, the improvement of reliability including safe mission abort capability are driving this idea. Although there are ideas of semi-reusable launch vehicles, typically two stages vehicles - reusable first stage or booster(s) and expendable second or upper stage - it should be kept in mind that the benefit of reusability will only overwhelm if there is a big enough share influencing the cost calculation. Today there is the understanding that additional technology preparation and verification will be necessary to master reusability and get enough benefits compared with existing launch vehicles. This understanding is based on several technology and system concepts preparation and verification programmes mainly done in the US but partially also in Europe and Japan. The major areas of necessary further activities are: - System concepts including business plan considerations - Sub-system or component technologies refinement - System design and operation know-how and capabilities - Verification and demonstration oriented towards future mission mastering: One of the most important aspects for the creation of those coming programmes and activities will be the iterative process of requirements definition derived from concepts analyses including economical considerations and the results achieved and verified within technology and verification programmes. It is the intention of this paper to provide major trends for those requirements focused on future launch vehicles structures. This will include the aspects of requirements only valid for reusable launch vehicles and those common for expendable, semi-reusable and reusable launch vehicles. Structures and materials is and will be one of the
Further finite element structural analysis of FAST Load Assembly
The FAST (Fusion Advanced Study Torus) machine is a compact high magnetic field tokamak, that will allow to study in an integrated way the main operational issues relating to plasma-wall interaction, plasma operation and burning plasma physics in conditions relevant for ITER and DEMO. The present work deals with the structural analysis of the machine Load Assembly for a proposed new plasma scenario (10 MA – 8.5 T), aimed to increase the operational limits of the machine. A previous paper has dealt with an integrated set of finite element models (regarding a former reference scenario: 6.5 MA – 7.5 T) of the load assembly, including the Toroidal and Poloidal Field Coils and the supporting structure. This set of models has regarded the evaluation of magnetic field values, the evaluation of the electromagnetic forces and the temperatures in all the current-carrying conductors: these analysis have been a preparatory step for the evaluation of the stresses of the main structural components. The previous models have been analyzed further on and improved in some details, including the computation of the out-of-plane electromagnetic forces coming from the interaction between the poloidal magnetic field and the current flowing in the toroidal magnets. After this updating, the structural analysis has been executed, where all forces and temperatures, coming from the formerly mentioned most demanding scenario (10 MA – 8.5 T) and acting on the tokamak's main components, have been considered. The two sets of analysis regarding the reference scenario and the extreme one have been executed and a useful comparison has been carried on. The analyses were carried out by using the FEM code Ansys rel. 13
A quantitative and qualitative evaluation of 239 Pu mictodistribution in the structural elements of the interalveolar septa after inhalation of three plutonium compounds different in solubility is made. Thirty minutes after the inhalation 55.3-85.3% of plutonium (dioxide>nitrate>=citrate) was revealed in rhe cells, predominantly in the microphages. More than half of the isotope found in the noncellular elements, lies in the surface layer of the alveoli and the intercellular matter. First 239Pu is seen as ''stars'' of tracks (dioxide), mainly (nitrate) or exclusively (citrate) as individual tracks. The different extent of plutonium elimination from the interalveolar septa (dioxide239Pu from the cells is mainly determined by its escape from the macrophages (dioxide) or from all cellular elements (nitrate, citrate). Pentacin accelates elimination of plutonium from the most of the structural elements of the interalveolar septa (citrate>nitrate)
Alu element-containing RNAs maintain nucleolar structure and function.
Caudron-Herger, Maïwen; Pankert, Teresa; Seiler, Jeanette; Németh, Attila; Voit, Renate; Grummt, Ingrid; Rippe, Karsten
2015-11-12
Non-coding RNAs play a key role in organizing the nucleus into functional subcompartments. By combining fluorescence microscopy and RNA deep-sequencing-based analysis, we found that RNA polymerase II transcripts originating from intronic Alu elements (aluRNAs) were enriched in the nucleolus. Antisense-oligo-mediated depletion of aluRNAs or drug-induced inhibition of RNA polymerase II activity disrupted nucleolar structure and impaired RNA polymerase I-dependent transcription of rRNA genes. In contrast, overexpression of a prototypic aluRNA sequence increased both nucleolus size and levels of pre-rRNA, suggesting a functional link between aluRNA, nucleolus integrity and pre-rRNA synthesis. Furthermore, we show that aluRNAs interact with nucleolin and target ectopic genomic loci to the nucleolus. Our study suggests an aluRNA-based mechanism that links RNA polymerase I and II activities and modulates nucleolar structure and rRNA production. PMID:26464461
Finite element-finite difference thermal/structural analysis of large space truss structures
Warren, Andrew H.; Arelt, Joseph E.; Eskew, William F.; Rogers, Karen M.
1992-01-01
A technique of automated and efficient thermal-structural processing of truss structures that interfaces the finite element and finite difference method was developed. The thermal-structural analysis tasks include development of the thermal and structural math models, thermal analysis, development of an interface and data transfer between the models, and finally an evaluation of the thermal stresses and displacements in the structure. Consequently, the objective of the developed technique was to minimize the model development time, in order to assure an automatic transfer of data between the thermal and structural models as well as to minimize the computer resources needed for the analysis itself. The method and techniques described are illustrated on the thermal/structural analysis of the Space Station Freedom main truss.
An in situ approach to study trace element partitioning in the laser heated diamond anvil cell.
Petitgirard, S; Borchert, M; Andrault, D; Appel, K; Mezouar, M; Liermann, H-P
2012-01-01
Data on partitioning behavior of elements between different phases at in situ conditions are crucial for the understanding of element mobility especially for geochemical studies. Here, we present results of in situ partitioning of trace elements (Zr, Pd, and Ru) between silicate and iron melts, up to 50 GPa and 4200 K, using a modified laser heated diamond anvil cell (DAC). This new experimental set up allows simultaneous collection of x-ray fluorescence (XRF) and x-ray diffraction (XRD) data as a function of time using the high pressure beamline ID27 (ESRF, France). The technique enables the simultaneous detection of sample melting based to the appearance of diffuse scattering in the XRD pattern, characteristic of the structure factor of liquids, and measurements of elemental partitioning of the sample using XRF, before, during and after laser heating in the DAC. We were able to detect elements concentrations as low as a few ppm level (2-5 ppm) on standard solutions. In situ measurements are complimented by mapping of the chemical partitions of the trace elements after laser heating on the quenched samples to constrain the partitioning data. Our first results indicate a strong partitioning of Pd and Ru into the metallic phase, while Zr remains clearly incompatible with iron. This novel approach extends the pressure and temperature range of partitioning experiments derived from quenched samples from the large volume presses and could bring new insight to the early history of Earth. PMID:22299967
An in situ approach to study trace element partitioning in the laser heated diamond anvil cell
Data on partitioning behavior of elements between different phases at in situ conditions are crucial for the understanding of element mobility especially for geochemical studies. Here, we present results of in situ partitioning of trace elements (Zr, Pd, and Ru) between silicate and iron melts, up to 50 GPa and 4200 K, using a modified laser heated diamond anvil cell (DAC). This new experimental set up allows simultaneous collection of x-ray fluorescence (XRF) and x-ray diffraction (XRD) data as a function of time using the high pressure beamline ID27 (ESRF, France). The technique enables the simultaneous detection of sample melting based to the appearance of diffuse scattering in the XRD pattern, characteristic of the structure factor of liquids, and measurements of elemental partitioning of the sample using XRF, before, during and after laser heating in the DAC. We were able to detect elements concentrations as low as a few ppm level (2-5 ppm) on standard solutions. In situ measurements are complimented by mapping of the chemical partitions of the trace elements after laser heating on the quenched samples to constrain the partitioning data. Our first results indicate a strong partitioning of Pd and Ru into the metallic phase, while Zr remains clearly incompatible with iron. This novel approach extends the pressure and temperature range of partitioning experiments derived from quenched samples from the large volume presses and could bring new insight to the early history of Earth.
Nuclear structure studies towards superheavy elements and perspectives with AGATA
A variety of theoretical approaches have been used to calculate the shell closure of spherical Super Heavy Elements (SHE) but the predictions of the location of the 'island of stability' vary from Z=114 to 120 and 126, with neutron numbers around N=172 or N=184 depending on the model employed. A deformed minimum around Z=108 and N=162 is predicted and an increase of the half-life of Hassium (Z=108) is experimentally observed when approaching the neutron number N=162. Super heavy nuclei are produced with very low cross-section (a few picobarns) and this makes their spectroscopic study impossible with today's beam intensities and detectors. However, important information can be obtained from the structure of mid-shell deformed nuclei (Z∼104) where selected single particle orbitals, which lie close to the spherical shell gap in SHE, are close to the Fermi level. The information will come from decay and in-beam spectroscopy. A promising area of progress, using the state-of-the art instruments, is represented by the observation of rotational gamma-ray transitions in No and Fm isotopes showing the deformed character of these nuclei. One of the objectives and focus of the nuclear structure community is related to the investigation of Single particle excitations beyond the N=152 neutron gap and collective properties of heavier systems towards Z∼104. The IN2P3-JINR collaboration has launched a project of electron and gamma-ray spectroscopy studies of heavy nuclei at the FLNR. This project benefits from the radioactive actinide targets uniquely available at Dubna and from the very intense stable beams provided by the U400 cyclotron. This offers a unique opportunity for the study of nuclei above Z=100 along an isotopic chain approaching N=162. In this contribution, the emphasis will be on the GABRIELA project and its issues. I will finally point out the perspectives with the new generation of gamma detectors such as AGATA
Finite element modeling of multilayered structures of fish scales.
Chandler, Mei Qiang; Allison, Paul G; Rodriguez, Rogie I; Moser, Robert D; Kennedy, Alan J
2014-12-01
The interlinked fish scales of Atractosteus spatula (alligator gar) and Polypterus senegalus (gray and albino bichir) are effective multilayered armor systems for protecting fish from threats such as aggressive conspecific interactions or predation. Both types of fish scales have multi-layered structures with a harder and stiffer outer layer, and softer and more compliant inner layers. However, there are differences in relative layer thickness, property mismatch between layers, the property gradations and nanostructures in each layer. The fracture paths and patterns of both scales under microindentation loads were different. In this work, finite element models of fish scales of A. spatula and P. senegalus were built to investigate the mechanics of their multi-layered structures under penetration loads. The models simulate a rigid microindenter penetrating the fish scales quasi-statically to understand the observed experimental results. Study results indicate that the different fracture patterns and crack paths observed in the experiments were related to the different stress fields caused by the differences in layer thickness, and spatial distribution of the elastic and plastic properties in the layers, and the differences in interface properties. The parametric studies and experimental results suggest that smaller fish such as P. senegalus may have adopted a thinner outer layer for light-weighting and improved mobility, and meanwhile adopted higher strength and higher modulus at the outer layer, and stronger interface properties to prevent ring cracking and interface cracking, and larger fish such as A. spatula and Arapaima gigas have lower strength and lower modulus at the outer layers and weaker interface properties, but have adopted thicker outer layers to provide adequate protection against ring cracking and interface cracking, possibly because weight is less of a concern relative to the smaller fish such as P. senegalus. PMID:25300062
Structural finite element analysis of ITER In-wall shield
The In-wall shielding (IWS) located between two shells of the vacuum vessel is part of the vacuum vessel of ITER. The function of the IWS is to provide neutron shielding and to reduce toroidal field ripple. The IWS plates are fastened using M30 bolts to hold them securely and the IWS blocks are mounted to the support ribs using the brackets and M20 bolts. The paper presents a structural finite element analysis of one sample IWS block carried out using ANSYS* to establish the benchmark analysis procedure of the IWS blocks. Boundary conditions are set taking into account the assembly procedure of the IWS blocks. The analysis is carried out in three load steps (1). Pretension on M30 (2). Pretension on M30 and M20 and (3) pretension on M30 and M20 plus Electromagnetic forces, dynamic forces, Seismic forces, etc. The stresses and displacements of individual IWS components are evaluated against their allowable stress limits as per an ASME guideline. The ITER-India’s results of analysis are compared with the ITER-IO’s results for the worst category 3-load step 3 and they are found comparable. This establishes the analysis procedure to be used for all of the IWS blocks
Stochastic structural model of rock and soil aggregates by continuum-based discrete element method
WANG; Yuannian; ZHAO; Manhong; LI; Shihai; J.G.; Wang
2005-01-01
This paper first presents a stochastic structural model to describe the random geometrical features of rock and soil aggregates. The stochastic structural model uses mixture ratio, rock size and rock shape to construct the microstructures of aggregates,and introduces two types of structural elements (block element and jointed element) and three types of material elements (rock element, soil element, and weaker jointed element)for this microstructure. Then, continuum-based discrete element method is used to study the deformation and failure mechanism of rock and soil aggregate through a series of loading tests. It is found that the stress-strain curve of rock and soil aggregates is nonlinear, and the failure is usually initialized from weaker jointed elements. Finally, some factors such as mixture ratio, rock size and rock shape are studied in detail. The numerical results are in good agreement with in situ test. Therefore, current model is effective for simulating the mechanical behaviors of rock and soil aggregates.
Kusulidu, L K; Karpova, N N; Razorenova, O V; Glukhov, I A; Kim, A I; Liubomirskaia, N V; Il'in, Iu V
2001-12-01
Distribution of two structural functional variants of the MDG4 (gypsy) mobile genetic element was examined in 44 strains of Drosophila melanogaster. The results obtained suggest that less transpositionally active MDG4 variant is more ancient component of the Drosophila genome. Using Southern blotting, five strains characterized by increased copy number of MDG4 with significant prevalence of the active variant over the less active one were selected for further analysis. Genetic analysis of these strains led to the suggestion that some of them carry factors that mobilize MDG4 independently from the cellular flamenco gene known to be responsible for transposition of this element. Other strains probably contained a suppressor of the flam- mutant allele causing active transpositions of the MDG4. Thus, the material for studying poorly examined relationships between the retrovirus and the host cell genome was obtained. PMID:11785284
Element Decoupling of 7T Dipole Body Arrays by EBG Metasurface Structures: Experimental Verification
Hurshkainen, Anna A; Glybovski, Stanislav B; Voogt, Ingmar J; Melchakova, Irina V; Berg, Cornelis A T van den; Raaijmakers, Alexander J E
2016-01-01
Metasurfaces are artificial electromagnetic boundaries or interfaces usually implemented as two-dimensional periodic structures with subwavelength periodicity and engineered properties of constituent unit cells. The electromagnetic bandgap (EBG) effect in metasurfaces prevents all surface modes from propagating in a certain frequency band. While metasurfaces provide a number of important applications in microwave antennas and antenna arrays, their features are also highly suitable for MRI applications. In this work we manufacture and experimentally study finite samples based on mushroom-type EBG metasurfaces and employ them for suppression of inter-element coupling in dipole transmit coil arrays for body imaging at 7T. We show experimentally that employment of the samples EBG leads to reduction of coupling between adjacent closely-spaced dipole antenna elements of a 7T transmit/receive body array, which reduces scattering losses in neighboring channels and thereby improves the B1+ efficiency. The setup consis...
Infinite elements for soil-structure interaction analysis in multi-layered halfspaces
Yun, Chung Bang; Kim, Jae Min [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of); Yang, Shin Chu [Korea High Speed Rail Construction Authority, Seoul (Korea, Republic of)
1994-07-01
This paper presents the theoretical aspects of a computer code (KIESSI) for soil-structure interaction analysis in a multi-layered halfspace using infinite elements. The shape functions of the infinite elements are derived from approximate expressions of the analytical solutions. Three different infinite elements are developed. They are the horizontal, the vertical and the comer infinite elements (HIE, VIE and CIE). Numerical example analyses are presented for demonstrating the effectiveness of the proposed infinite elements.
Structure of a conjugative element in Streptococcus pneumoniae
Vijayakumar, M.N.; Priebe, S.D.; Guild, W.R.
1986-06-01
The authors have cloned and mapped a 69-kilobase (kb) region of the chromosome of Streptococcus pneumoniae DP1322, which carries the conjugative Omega(cat-tet) insertion from S. pneumoniae BM6001. This element proved to be 65.5 kb in size. Location of the junctions was facilitated by cloning a preferred target region from the wild-type strain Rx1 recipient genome. This target site was preferred by both the BM6001 element and the cat-erm-tet element from Streptococcus agalactiae B109. Within the BM6001 element cat and tet were separated by 30 kb, and cat was flanked by two copies of a sequence that was also present in the recipient strain Rx1 DNA. Another sequence at least 2.4 kb in size was found inside the BM6001 element and at two places in the Rx1 genome. Its role is unknown. The ends of the BM6001 element appear to be the same as those of the B109 element, both as seen after transfer to S. pneumoniae and as mapped by others in pDP5 after transposition in Streptococcus faecalis. No homology is seen between the ends of the BM6001 element and no evidence found suggesting that it ever circularizes.
That study focuses on concrete structures submitted to impact loading and is aimed at predicting local damage in the vicinity of an impact zone as well as the global response of the structure. The Discrete Element Method (DEM) seems particularly well suited in this context for modeling fractures. An identification process of DEM material parameters from macroscopic data (Young's modulus, compressive and tensile strength, fracture energy, etc.) will first be presented for the purpose of enhancing reproducibility and reliability of the simulation results with DE samples of various sizes. Then, a particular interaction, between concrete and steel elements, was developed for the simulation of reinforced concrete. The discrete elements method was validated on quasi-static and dynamic tests carried out on small samples of concrete and reinforced concrete. Finally, discrete elements were used to simulate impacts on reinforced concrete slabs in order to confront the results with experimental tests. The modeling of a large structure by means of DEM may lead to prohibitive computation times. A refined discretization becomes required in the vicinity of the impact, while the structure may be modeled using a coarse FE mesh further from the impact area, where the material behaves elastically. A coupled discrete-finite element approach is thus proposed: the impact zone is modeled by means of DE and elastic FE are used on the rest of the structure. An existing method for 3D finite elements was extended to shells. This new method was then validated on many quasi-static and dynamic tests. The proposed approach is then applied to an impact on a concrete structure in order to validate the coupled method and compare computation times. (author)
FINITE ELEMENT ANALYSIS OF THE FATIGUE BEHAVIOR OF WOOD FIBER CELL WALLS
Phichit Somboon
2008-11-01
Full Text Available The fatigue behavior of the wood fiber cell wall under mechanical treatment in refining was simulated dynamically using a finite element method. The effect of the amplitude and frequency of impacts on the mechanical breakdown of the fiber wall structure was examined. The proposed model of the fiber cell wall was constructed from elementary microfibrils in various orientations embedded in isotropic lignin. The fatigue of the cell wall was simulated under normal refiner mechanical pulping conditions. A cyclic load was applied on the model fiber through a hemispherical grit proposed to be applied on the surface on refiner segments. Changes in the elastic modulus of the cell wall were analyzed to determine the potential for cell wall breakdown. An increase in the amplitude of applied forces and frequency of impacts was found to have a significant influence on the reduction of the elastic modulus of the wall structure. A high frequency of impacts increased the stiffness of the cell wall, but resulted in faster reduction of the elastic modulus. At a lower amplitude of impacts, efficient breakdown of the cell wall using grits was achieved with a high frequency of impacts or a high rotational speed of refiners.
The relationship among the fragility of element, that of story and that of system, is examined using the Monte Carlo simulation. In this study, 2-story models whose stories consist of 2 ductile elements are employed. A method is proposed which includes a nonlinear effect into the evaluation of elements capacities. This method does not require the nonlinear MCS, therefore saving computational efforts. Also, a method to estimate the stories and the system fragilities is proposed. (author). 2 refs., 7 figs., 3 tabs
Nguyen-Van, H.; Mai-Duy, N.; Tran-Cong, T.
2008-06-01
This paper reports numerical analyses of free vibration of laminated composite plate/shell structures of various shapes, span-to-thickness ratios, boundary conditions and lay-up sequences. The method is based on a novel four-node quadrilateral element, namely MISQ20, within the framework of the first-order shear deformation theory (FSDT). The element is built by incorporating a strain smoothing method into the bilinear four-node quadrilateral finite element where the strain smoothing operation is based on mesh-free conforming nodal integration. The bending and membrane stiffness matrices are based on the boundaries of smoothing cells while the shear term is evaluated by 2×2 Gauss quadrature. Through several numerical examples, the capability, efficiency and simplicity of the element are demonstrated. Convergence studies and comparison with other existing solutions in the literature suggest that the present element is robust, computationally inexpensive and free of locking.
The relationship among the fragility of element, that of story and that of system, is examined using the Monte Carlo simulation. In this study, 2-story models whose stories consist of 2 brittle elements are employed. Through the simulation, the feature of the failure of brittle elements is derived. From this results, 2 methods to evaluate the fragility of brittle element are presented. Also, a method to estimate the fragilities of the story and the system are presented. (author). 2 refs., 7 figs., 4 tabs
Functional analysis of the sea urchin-derived arylsulfatase (Ars)-element in mammalian cells.
Watanabe, Satoshi; Watanabe, Sachiko; Sakamoto, Naoaki; Sato, Masahiro; Akasaka, Koji
2006-09-01
An insulator is a DNA sequence that has both enhancer-blocking activity, through its ability to modify the influence of neighboring cis-acting elements, and a barrier function that protects a transgene from being silenced by surrounding chromatin. Previously, we isolated and characterized a 582-bp-long element from the sea urchin arylsulfatase gene (Ars). This Ars-element was effective in sea urchin and Drosophila embryos and in plant cells. To investigate Ars-element activity in mammalian cells, we placed the element between the cytomegalovirus enhancer and a luciferase (luc) expression cassette. In contrast to controls lacking the Ars-element, NIH3T3 and 293T cells transfected with the element-containing construct displayed reduced luciferase activities. The Ars-element therefore acts as an enhancer-blocking element in mammalian cells. We assessed the barrier activity of the Ars-element using vectors in which a luc expression cassette was placed between two elements. Transfection experiments demonstrated that luc activity in these vectors was approximately ten-fold higher than in vectors lacking elements. Luc activities were well maintained even after 12 weeks in culture. Our observations demonstrate that the Ars-element has also a barrier activity. These results indicated that the Ars-element act as an insulator in mammalian cells. PMID:16923122
The Structure of a Rigorously Conserved RNA Element within the SARS Virus Genome
Robertson Michael P
2004-01-01
Full Text Available We have solved the three-dimensional crystal structure of the stem-loop II motif (s2m RNA element of the SARS virus genome to 2.7-A resolution. SARS and related coronaviruses and astroviruses all possess a motif at the 3' end of their RNA genomes, called the s2m, whose pathogenic importance is inferred from its rigorous sequence conservation in an otherwise rapidly mutable RNA genome. We find that this extreme conservation is clearly explained by the requirement to form a highly structured RNA whose unique tertiary structure includes a sharp 90degrees kink of the helix axis and several novel longer-range tertiary interactions. The tertiary base interactions create a tunnel that runs perpendicular to the main helical axis whose interior is negatively charged and binds two magnesium ions. These unusual features likely form interaction surfaces with conserved host cell components or other reactive sites required for virus function. Based on its conservation in viral pathogen genomes and its absence in the human genome, we suggest that these unusual structural features in the s2m RNA element are attractive targets for the design of anti-viral therapeutic agents. Structural genomics has sought to deduce protein function based on three-dimensional homology. Here we have extended this approach to RNA by proposing potential functions for a rigorously conserved set of RNA tertiary structural interactions that occur within the SARS RNA genome itself. Based on tertiary structural comparisons, we propose the s2m RNA binds one or more proteins possessing an oligomer-binding-like fold, and we suggest a possible mechanism for SARS viral RNA hijacking of host protein synthesis, both based upon observed s2m RNA macromolecular mimicry of a relevant ribosomal RNA fold.
Elemental structure in Si(110)-'16x2' revealed by scanning tunneling microscopy
Atomic structures of the clean Si(110)-'16x2' surface are studied by scanning tunneling microscopy (STM). High-resolution STM images reveal that the elemental structure in the '16x2' is a pair of pentagons. In the empty-states images the elemental structure is clearly resolved in ten protrusions, while in eight in the filled-states images. In order to clarify the atomic arrangement of the pentagons, we pay attention to the disordered area where the elemental structures are isolated on the bulk-terminated surface. The bulk-terminated surface structure, on which the pentagons are located, is well understood by the rotational-relaxation structural model. In consideration of the registry of the pentagon for the rotational-relaxation structure, a 'tetramer-interstitial' model is proposed for the elemental structure, together with three other possible structural models
Formation and finite element analysis of tethered bilayer lipid structures.
Kwak, Kwang Joo; Valincius, Gintaras; Liao, Wei-Ching; Hu, Xin; Wen, Xuejin; Lee, Andrew; Yu, Bo; Vanderah, David J; Lu, Wu; Lee, L James
2010-12-01
Rapid solvent exchange of an ethanolic solution of diphytanoyl phosphatidylcholine (DPhyPC) in the presence of a mixed self-assembled monolayer (SAM) [thiolipid/β-mercaptoethanol (βME) (3/7 mol/mol) on Au] shows a transition from densely packed tethered bilayer lipid membranes [(dp)tBLMs], to loosely packed tethered bilayer lipid membranes [(lp)tBLMs], and tethered bilayer liposome nanoparticles (tBLNs) with decreasing DPhyPC concentration. The tethered lipidic constructs in the aqueous medium were analyzed by atomic force microscopy (AFM) and electrochemical impedance spectroscopy (EIS). Finite element analysis (FEA) was applied to interpret spectral EIS features without referring to equivalent circuit modeling. Using structural data obtained earlier from neutron reflectometry and dielectric constants of lipid bilayers, we reproduced experimentally observed features of the electrochemical impedance (EI) spectra of complex surface constructs involving small pinhole defects, large membrane-free patches, and bound liposomes. We demonstrated by FEA that highly insulating (dp)tBLMs with low-defect density exhibit EI spectra in the shape of a perfect semicircle with or without low-frequency upward "tails" in the Cole-Cole representation. Such EI spectra were observed at DPhyPC concentrations of >5 × 10(-3) mol L(-1). While AFM was not able to visualize very small lateral defects in such films, EI spectra unambiguously signaled their presence by increased low frequency "tails". Using FEA we demonstrate that films with large diameter visible defects (>25 nm by AFM) produce EI spectral features consisting of two semicircles of comparable size. Such films were typically obtained at DPhyPC concentrations of FEA revealed that, to account for these EI features for bound liposome systems (50-500 nm diameter), one needs to assume much lower tBLM conductivities of the submembrane space, which separates the electrode surface and the phospholipid bilayer. Alternatively, FEA
Schmid, G.; Wang, S.; Chouw, N.
1991-04-01
SSI-FEBEM is a computer program for dynamic soil-structure (or structure-soil-structure) interaction analysis in the frequency domain. The program SAP IV (FEM) and the program SSI 2D/3D (BEM) have been integrated into a new program, which allows a coupling of finite and boundary elements. It is applicable to two- and three-dimensional problems. In this manual, the theoretical concept for both FEM and BEM, as used in the program, are briefly introduced. Details of the coupling of FE and BE, are also discussed. However, emphasis is directed towards the use of the computer program concerning data input and output. Finally, several examples on soil-structure interaction (SSI) and structure-soil-structure interaction (SSSI), together with their data are presented. (orig.). [Deutsch] SSI-FEBEM ist ein Programm zur Berechnung der dynamischen Antwort eines Systems Bauwerk-Boden (oder Bauwerk-Boden-Bauwerk) im Frequenzbereich. Das Programm besteht aus dem Programm SAP IV (FEM) und dem Programm SSI 2D/3D (BEM) und koppelt Finite Elemente und Randelemente. Zwei- und dreidimensionale Probleme koennen damit behandelt werden. In dem vorliegenden Bericht werden die theoretischen Grundlagen der angewendeten Methode der Finiten Elemente und der Randelemente kurz vorgestellt und deren Kopplung beschrieben. Der Bericht ist als Benutzerhandbuch anzusehen. Er beinhaltet auch Beispiele der Wechselwirkung zwischen Bauwerk und Baugrund (SSI) und zwischen Bauwerk-Boden-Bauwerk (SSSI). (orig.).
U.S. Geological Survey, Department of the Interior — The Positive Structural Elements coverage maps, in the form of polygons, are known structural highs within the province that commonly define a basin proper or...
Experimentally validated finite element model of electrocaloric multilayer ceramic structures
A novel finite element model to simulate the electrocaloric response of a multilayer ceramic capacitor (MLCC) under real environment and operational conditions has been developed. The two-dimensional transient conductive heat transfer model presented includes the electrocaloric effect as a source term, as well as accounting for radiative and convective effects. The model has been validated with experimental data obtained from the direct imaging of MLCC transient temperature variation under application of an electric field. The good agreement between simulated and experimental data, suggests that the novel experimental direct measurement methodology and the finite element model could be used to support the design of optimised electrocaloric units and operating conditions.
Element-by-element model updating of large-scale structures based on component mode synthesis method
Yu, Jie-xin; Xia, Yong; Lin, Wei; Zhou, Xiao-qing
2016-02-01
Component mode synthesis (CMS) method is developed and applied to the element-by-element model updating of large-scale structures in this study. Several lowest frequencies and mode shapes of the global structure are obtained with the free interface CMS method by employing the several lowest frequencies and mode shapes of each substructure individually. In this process, the removal of higher modes is compensated by the residual modes. The eigensensitivity of the global structure is then assembled from the eigensensitivities of each substructure to the updating element parameters. Subsequently, the global model is updated using the sensitivity-based optimization technique. The application of the present method to an 11-floor frame structure and to a large-scale structure demonstrates its accuracy and efficiency. The computational time required by the substructuring method to calculate the eigensensitivity matrices is significantly reduced, as compared with that consumed by the conventional global-based approach. Selection of the number of master modes is also proposed.
Efficient Finite Element Analysis of Inelastic Structures with Iterative Solvers
Quint, K.J.; Hartmann, S.; Duintjer Tebbens, Jurjen; Meister, A.
2008-01-01
Roč. 8, č. 1 (2008), s. 10331-10332. ISSN 1617-7061 R&D Projects: GA AV ČR KJB100300703 Institutional research plan: CEZ:AV0Z10300504 Keywords : inexact multilevel- Newton * diagonally implicit Runge-Kutta * finite element analysis * linear solver * preconditioning * adaptive stopping criterion Subject RIV: BA - General Mathematics
Elemental and structural studies at the bone-cartilage interface
Kaabar, W., E-mail: w.kaabar@surrey.ac.uk [Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom); Daar, E. [Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom); Bunk, O. [Swiss Light Source, Paul Scherrer Institute, 5232 Villigen (Switzerland); Farquharson, M.J. [Department of Medical Physics and Applied Radiation Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4K1 (Canada); Laklouk, A. [Al-Fateh University, Tripoli (Libya); Bailey, M.; Jeynes, C. [Surrey Ion Beam Centre, University of Surrey, Guildford GU2 7XH (United Kingdom); Gundogdu, O. [Umuttepe Campus, University of Kocaeli, 41380 Kocaeli (Turkey); Bradley, D.A. [Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom)
2011-10-01
Micro-Proton Induced X-ray Emission ({mu}-PIXE) and Proton Induced Gamma-ray Emission (PIGE) techniques were employed in the investigation of trace and essential elements distribution in normal and diseased human femoral head sections affected by osteoarthritis (OA). PIGE was exploited in the determination of elements of low atomic number z<15 such as Na and F whereas elements with z>15 viz Ca, Z, P and S were determined by PIXE. Accumulations of key elements in the bone and cartilage sections were observed, significant S and Na concentrations being found in the cartilage region particularly in normal tissues. Zn showed enhanced concentrations at the bone-cartilage interface. At a synchrotron facility, small angle X-ray scattering (SAXS) was utilized on a decalcified human femoral head section affected by OA, direct measurements being made of spatial alterations of collagen fibres. The SAXS results showed a slight decrease in the axial periodicity between normal collagen type I and that in diseased tissue in various sites, in contrast with the findings of others.
A three-dimensional finite element model of an adherent eukaryotic cell
McGarry J. G.
2004-04-01
Full Text Available Mechanical stimulation is known to cause alterations in the behaviour of cells adhering to a substrate. The mechanisms by which forces are transduced into biological responses within the cell remain largely unknown. Since cellular deformation is likely involved, further understanding of the biomechanical origins of alterations in cellular response can be aided by the use of computational models in describing cellular structural behaviour and in determining cellular deformation due to imposed loads of various magnitudes. In this paper, a finite element modelling approach that can describe the biomechanical behaviour of adherent eukaryotic cells is presented. It fuses two previous modelling approaches by incorporating, in an idealised geometry, all cellular components considered structurally significant, i.e. prestressed cytoskeleton, cytoplasm, nucleus and membrane components. The aim is to determine if we can use this model to describe the non-linear structural behaviour of an adherent cell and to determine the contribution of the various cellular components to cellular stability. Results obtained by applying forces (in the picoNewton range to the model membrane nodes suggest a key role for the cytoskeleton in determining cellular stiffness. The model captures non-linear structural behaviours such as strain hardening and prestress effects (in the region of receptor sites, and variable compliance along the cell surface. The role of the cytoskeleton in stiffening a cell during the process of cell spreading is investigated by applying forces to five increasingly spread cell geometries. Parameter studies reveal that material properties of the cytoplasm (elasticity and compressibility also have a large influence on cellular stiffness. The computational model of a single cell developed here is proposed as one that is sufficiently complex to capture the non-linear behaviours of the cell response to forces whilst not being so complex that the parameters
Yang, Weizhu; Yue, Zhufeng; Li, Lei; Wang, Peiyan
2016-01-01
An optimization procedure combining an automated finite element modelling (AFEM) technique with a ground structure approach (GSA) is proposed for structural layout and sizing design of aircraft wings. The AFEM technique, based on CATIA VBA scripting and PCL programming, is used to generate models automatically considering the arrangement of inner systems. GSA is used for local structural topology optimization. The design procedure is applied to a high-aspect-ratio wing. The arrangement of the integral fuel tank, landing gear and control surfaces is considered. For the landing gear region, a non-conventional initial structural layout is adopted. The positions of components, the number of ribs and local topology in the wing box and landing gear region are optimized to obtain a minimum structural weight. Constraints include tank volume, strength, buckling and aeroelastic parameters. The results show that the combined approach leads to a greater weight saving, i.e. 26.5%, compared with three additional optimizations based on individual design approaches.
Distortional Mechanics of Thin-Walled Structural Elements
Andreassen, Michael Joachim
number of degrees of freedom. This means that the classical Vlasov thin-walled beam theory for open and closed cross sections is generalized as part of a semi-discretization process by including distortional displacement fields. A novel finite-element-based displacement approach is used in combination...... homogeneous and non-homogeneous differential equations and the related solutions. The developed semi-discretization approach to Generalized Beam Theory (GBT) is furthermore extended to include the geometrical stiffness terms for column buckling analysis based on an initial stress approach. Through variations......-section displacement mode shapes and buckling load factor are given. In order to handle arbitrary boundary conditions as well as the possibility to add concentrated loads as nodal loads the formulation of a generalized onedimensional semi-discretized thin-walled beam element including distortional contributions is...
Application of Finite Element Method to Analyze Inflatable Waveguide Structures
Deshpande, M. D.
1998-01-01
A Finite Element Method (FEM) is presented to determine propagation characteristics of deformed inflatable rectangular waveguide. Various deformations that might be present in an inflatable waveguide are analyzed using the FEM. The FEM procedure and the code developed here are so general that they can be used for any other deformations that are not considered in this report. The code is validated by applying the present code to rectangular waveguide without any deformations and comparing the numerical results with earlier published results.
Elemental and structural studies at the bone-cartilage interface
Micro-Proton Induced X-ray Emission (μ-PIXE) and Proton Induced Gamma-ray Emission (PIGE) techniques were employed in the investigation of trace and essential elements distribution in normal and diseased human femoral head sections affected by osteoarthritis (OA). PIGE was exploited in the determination of elements of low atomic number z15 viz Ca, Z, P and S were determined by PIXE. Accumulations of key elements in the bone and cartilage sections were observed, significant S and Na concentrations being found in the cartilage region particularly in normal tissues. Zn showed enhanced concentrations at the bone-cartilage interface. At a synchrotron facility, small angle X-ray scattering (SAXS) was utilized on a decalcified human femoral head section affected by OA, direct measurements being made of spatial alterations of collagen fibres. The SAXS results showed a slight decrease in the axial periodicity between normal collagen type I and that in diseased tissue in various sites, in contrast with the findings of others.
Elemental and structural studies at the bone-cartilage interface
Kaabar, W.; Daar, E.; Bunk, O.; Farquharson, M. J.; Laklouk, A.; Bailey, M.; Jeynes, C.; Gundogdu, O.; Bradley, D. A.
2011-10-01
Micro-Proton Induced X-ray Emission (μ-PIXE) and Proton Induced Gamma-ray Emission (PIGE) techniques were employed in the investigation of trace and essential elements distribution in normal and diseased human femoral head sections affected by osteoarthritis (OA). PIGE was exploited in the determination of elements of low atomic number z15 viz Ca, Z, P and S were determined by PIXE. Accumulations of key elements in the bone and cartilage sections were observed, significant S and Na concentrations being found in the cartilage region particularly in normal tissues. Zn showed enhanced concentrations at the bone-cartilage interface. At a synchrotron facility, small angle X-ray scattering (SAXS) was utilized on a decalcified human femoral head section affected by OA, direct measurements being made of spatial alterations of collagen fibres. The SAXS results showed a slight decrease in the axial periodicity between normal collagen type I and that in diseased tissue in various sites, in contrast with the findings of others.
Blood lead: Its effect on trace element levels and iron structure in hemoglobin
Jin, C. [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100039 (China); Li, Y. [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China)], E-mail: LY@sinap.ac.cn; Li, Y.L. [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Zou, Y. [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100039 (China); Zhang, G.L. [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Normura, M. [Photon Factory, Institute of Materials Structure Science, KEK, Oho, Tsukuba 305 (Japan); Zhu, G.Y. [Institute of Radiation Medicine, Fudan University, Shanghai 200032 (China)
2008-08-15
Lead is a ubiquitous environmental pollutant that induce a broad range of physiological and biochemical dysfunctions. The purpose of this study was to investigate its effects on trace elements and the iron structure in hemoglobin. Blood samples were collected from rats that had been exposed to lead. The concentration of trace elements in whole blood and blood plasma was determined by ICP-MS and the results indicate that lead exists mainly in the red blood cells and only about 1-3% in the blood plasma. Following lead exposure, the concentrations of zinc and iron in blood decrease, as does the hemoglobin level. This indicates that the heme biosynthetic pathway is inhibited by lead toxicity and that lead poisoning-associated anemia occurs. The selenium concentration also decreases after lead exposure, which may lead to an increased rate of free radical production. The effect of lead in the blood on iron structure in hemoglobin was determined by EXAFS. After lead exposure, the Fe-O bond length increases by about 0.07 A and the Fe-Np bond length slightly increases, but the Fe-N{sub {epsilon}} bond length remains unchanged. This indicates that the blood content of Hb increases, but that the content of HbO{sub 2} decreases.
A combined wet/dry sipping cell for TRIGA fuel element tests
A combined wet/dry sipping cell for the investigation of research reactor fuel elements was developed and tested. It is capable of detecting temperature-dependent cladding failures through the release of gaseous fission products. Several TRIGA fuel elements were tested both in the wet in the dry sipping mode. Some elements released fission gases only above 75deg C. (orig.)
A new structure of two-dimensional allotropes of group V elements
Ping Li; Weidong Luo
2016-01-01
The elemental two-dimensional (2D) materials such as graphene, silicene, germanene, and black phosphorus have attracted considerable attention due to their fascinating physical properties. Structurally they possess the honeycomb or distorted honeycomb lattices, which are composed of six-atom rings. Here we find a new structure of 2D allotropes of group V elements composed of eight-atom rings, which we name as the octagonal tiling (OT) structure. First-principles calculations indicate that the...
Philosophy of mathematics and deductive structure in Euclid's elements
Mueller, Ian
2006-01-01
A survey of Euclid's Elements, this text provides an understanding of the classical Greek conception of mathematics. It offers a well-rounded perspective, examining similarities to modern views as well as differences. Rather than focusing strictly on historical and mathematical issues, the book examines philosophical, foundational, and logical questions.Although comprehensive in its treatment, this study represents a less cumbersome, more streamlined approach than the classic three-volume reference by Sir Thomas L. Heath (also available from Dover Publications). To make reading easier and to f
Non-contact remote monitoring technique of reactor structural elements
This study aims at development of technique to measure and estimate, at high precision, fine machining scratch, crack and so on formed on grinding tubular elements, especially inner faces of small diameter tube at an optical mirror grade, and at establishment of estimation technique on reliability and soundness of the tubular elements. In this fiscal year, on optical type non-contact monitoring technique, investigations on optical illumination condition and holding accuracy required for the non-contact holding mechanism were conducted by using a sensor head trially produced in 1995 fiscal year. And, in order to realize a high precision non-contact holding in a tube of optical detection system to upgrade static holding properties (holding stiffness, holding attitude, and so on) of pneumatic type inner tube non-contact holding mechanism, realization of increase in supplying air pressure and experiments using a holding mechanism to increase pore numbers of air injecting nozzle were conducted. And, on materials surface technique, effect of difference in pre-machining method (cutting and bright annealing) at inner face of small diameter stainless tube on their smooth machining property was examined. (G.K.)
Structural elements and organization of the ancestral translational machinery
Rein, R.; Srinivasan, S.; McDonald, J.; Raghunathan, G.; Shibata, M.
1987-09-01
The molecular mechanisms underlying the primitive translational apparatus have been studied in light of present day protein biosynthesis. Using the structural information available from the contemporary system as a key to its function, both the structural necessities for an early adaptor and the multipoint recognition properties of such adaptors have been investigated. This was done by first critically examining the potential feasibility of right- and left-handed hairpin adaptor models. Second, a molecular model of the contemporary transpeptidation complex has been constructed in order to ascertain the structural requirements of the adaptor molecule needed for peptidyl transfer. Third, a model of the tRNATyr-tyrosyl tRNA synthetase complex including the positioning of the disordered region is proposed. This model is used to illustrate those required recognition properties of aminoacyl synthetase which lead to a perspective on the structure of the ancestor synthetase.
Inverse Finite Element Method Investigation for Adaptive Structures Project
National Aeronautics and Space Administration — This research project is evaluating an innovative technique that uses fiber optic strain sensors to measure structural deformations and full field strains. An...
Study of trace elements in cells using SPM, SR-XRM and PIXE
Trace elements play important roles in cells. Nuclear techniques as traditional PIXE, SPM and SR-XRM provide solid tools for quantitative element analysis. The article presents element-distribution maps of endometrium, nerve cell and relative quantity tables. Advantages of PIXE, SPM and SR-XRM techniques, especially in application to cell biology, are discussed. PIXE has a large beam and is convenient in measuring a large quantity of samples. SPM gives element-distribution maps owing to its high resolution. SR-XRM tells quantity of elements by its good sensitivity and nondestructive irradiation. The combination of PIXE, SPM and SR-XRM demonstrates that Zn is a component of cell membrane and is proved to be a complementary way which will open vast vistas for cell analysis. (author)
Some keys elements to structure the hybrid silicon oxides
The aim of this work is to use the intermolecular interactions properties of the organic fragments of the organo-silane to control the structuration of these hybrids from the molecular passing from the supramolecular. In this work, formation mechanisms of these solids are approached and discussed in terms of the organic fragment structure, the auto-association properties and the experimental conditions (temperature, solvent, catalyst, process...). (O.M.)
Nondestructive evaluation of critical composite material structural elements
Duke, John C., Jr.; Lesko, John J.; Weyers, R.
1996-11-01
A small span bridge that has suffered corrosive deterioration of a number of the steel structural members is in the process of being rehabilitated with glass and carbon fiber reinforced, pultruded polymer structural beams. As part of a comprehensive research program to develop methods for modeling long term durability of the composite material, nondestructive evaluation if being used to provide a preliminary assessment of the initial condition of the beams as well as to monitor the deterioration of the beams during service.
Structure Motivator: A tool for exploring small three-dimensional elements in proteins
Leader David P
2012-10-01
Full Text Available Abstract Background Protein structures incorporate characteristic three-dimensional elements defined by some or all of hydrogen bonding, dihedral angles and amino acid sequence. The software application, Structure Motivator, allows interactive exploration and analysis of such elements, and their resolution into sub-classes. Results Structure Motivator is a standalone application with an embedded relational database of proteins that, as a starting point, can furnish the user with a palette of unclassified small peptides or a choice of pre-classified structural motifs. Alternatively the application accepts files of data generated externally. After loading, the structural elements are displayed as two-dimensional plots of dihedral angles (φ/ψ, φ/χ1 or in combination for each residue, with visualization options to allow the conformation or amino acid composition at one residue to be viewed in the context of that at other residues. Interactive selections may then be made and structural subsets saved to file for further sub-classification or external analysis. The application has been applied both to classical motifs, such as the β-turn, and ‘non-motif’ structural elements, such as specific segments of helices. Conclusions Structure Motivator allows structural biologists, whether or not they possess computational skills, to subject small structural elements in proteins to rapid interactive analysis that would otherwise require complex programming or database queries. Within a broad group of structural motifs, it facilitates the identification and separation of sub-classes with distinct stereochemical properties.
A boundary element model for structural health monitoring using piezoelectric transducers
In this paper, for the first time, the boundary element method (BEM) is used for modelling smart structures instrumented with piezoelectric actuators and sensors. The host structure and its cracks are formulated with the 3D dual boundary element method (DBEM), and the modelling of the piezoelectric transducers implements a 3D semi-analytical finite element approach. The elastodynamic analysis of the structure is performed in the Laplace domain and the time history is obtained by inverse Laplace transform. The sensor signals obtained from BEM simulations show excellent agreement with those from finite element modelling simulations and experiments. This work provides an alternative methodology for modelling smart structures in structural health monitoring applications. (paper)
APPLICATION OF VIRTUAL LAMINATED ELEMENT IN THE TOPOLOGY OPTIMIZATION OF STRUCTURES
徐兴; 李芳; 凌道盛
2001-01-01
This paper presents the topology optimization design of structures composed of plane stress elements. The authors' proposed method of topology optimization by virtual laminated element is based on the Evolutionary Structural Optimization (ESO) method of linear elasticity, but dose not require formation of as many elements as the conventional ESO method. The presented method has the important feature of reforming the stiffness matrix in generating optimum topology. Calculation results showed that this algorithm is simple and effective and can be applied for topology optimization of structures.
Semenova, I. V.; Belashov, A. V.; Dreiden, G. V.; Petrov, N. V.; Samsonov, A. M.
2015-05-01
Modern structural elements are often made of laminated polymer materials or composites on the base of polymer matrices. The proper functioning of these elements may be of vital importance especially in automotive and aerospace industries, in gas and oil transportation. The major problem in their performance is a possibility of a sudden and irreversible delamination caused by various factors. We propose and study a NDT approach aimed to detect delamination areas in adhesively bonded layered structural elements made of different materials. The proposed approach is evaluated by use of holographic detection and monitoring of the evolution of bulk strain solitons generated in such structures.
Structural elements in the Girk1 subunit that potentiate G protein-gated potassium channel activity.
Wydeven, Nicole; Young, Daniele; Mirkovic, Kelsey; Wickman, Kevin
2012-12-26
G protein-gated inwardly rectifying K(+) (Girk/K(IR)3) channels mediate the inhibitory effect of many neurotransmitters on excitable cells. Girk channels are tetramers consisting of various combinations of four mammalian Girk subunits (Girk1 to -4). Although Girk1 is unable to form functional homomeric channels, its presence in cardiac and neuronal channel complexes correlates with robust channel activity. This study sought to better understand the potentiating influence of Girk1, using the GABA(B) receptor and Girk1/Girk2 heteromer as a model system. Girk1 did not increase the protein levels or alter the trafficking of Girk2-containing channels to the cell surface in transfected cells or hippocampal neurons, indicating that its potentiating influence involves enhancement of channel activity. Structural elements in both the distal carboxyl-terminal domain and channel core were identified as key determinants of robust channel activity. In the distal carboxyl-terminal domain, residue Q404 was identified as a key determinant of receptor-induced channel activity. In the Girk1 core, three unique residues in the pore (P) loop (F137, A142, Y150) were identified as a collective potentiating influence on both receptor-dependent and receptor-independent channel activity, exerting their influence, at least in part, by enhancing mean open time and single-channel conductance. Interestingly, the potentiating influence of the Girk1 P-loop is tempered by residue F162 in the second membrane-spanning domain. Thus, discontinuous and sometime opposing elements in Girk1 underlie the Girk1-dependent potentiation of receptor-dependent and receptor-independent heteromeric channel activity. PMID:23236146
Finite element method in density functional theory electronic structure calculations
Vackář, Jiří; Čertík, Ondřej; Cimrman, R.; Novák, M.; Šipr, Ondřej; Plešek, Jiří
Berlin : Springer, 2012 - (Hoggan, P.; Brändas, E.; Maruani, J.; Piecuch, P.; Delgado- Barrio , G.), s. 199-217 ISBN 978-94-007-2075-6. - (Progress in Theoretical Chemistry and Physics. vol. 12) R&D Projects: GA ČR GA101/09/1630; GA ČR(CZ) GAP108/11/0853; GA MŠk(CZ) LC06040 Institutional research plan: CEZ:AV0Z10100520; CEZ:AV0Z10100521; CEZ:AV0Z20760514 Keywords : finite-element method * pseudopotentials * density functional theory Subject RIV: BM - Solid Matter Physics ; Magnetism http://www.springerlink.com/content/p7k3j7047720270r/
Broadband Analysis of Microwave Structures by Enhanced Finite-Element Methods
Z. Raida; Motl, M.
2005-01-01
The paper deals with the broadband modeling of microwave structures by finite-element methods. The attention is turned to original enhancements of accuracy, efficiency and stability of finite-element codes. The partial improvements are based on novel approximations both in the spatial domain and in the time one, in the adoption of complex frequency hopping, fast frequency sweep and envelope finite-element techniques. In the paper, a possible hybridization of approaches is discussed. Proposed ...
THE ESSENCE OF KAIZEN’S THEORETICAL, METHODOLOGICAL AND STRUCTURAL ELEMENTS
Oksanich E. A.; Rybyantseva M. S.; Moiseenko A. S.
2015-01-01
Investigations of kaizen’s methodological foundations are becoming increasingly important because of existence of multiple interpretations of kaizen, uncertainty of its elements. Kaizen is at the crossroads of accounting and management. It consists of elements that may be divided into groups: theoretical, methodical and structural. Theoretical elements define the methodological essence and consist of subjects, objects, principles, functions, etc. Classification identifies are allocated: aspec...
Associative structures in animal learning: dissociating elemental and configural processes.
Honey, Robert C; Iordanova, Mihaela D; Good, Mark
2014-02-01
The central concern of associative learning theory is to provide an account of behavioral adaptation that is parsimonious in addressing three key questions: (1) under what conditions does learning occur, (2) what are the associative structures involved, and (3) how do these affect behavior? The principle focus here is on the second question, concerning associative structures, but we will have cause to touch on the others in passing. This question is one that has exercised theorists since Pavlov's descriptions of the conditioning process, where he identifies the shared significance of the study of conditioned reflexes for psychologists and neuroscientists alike. PMID:23769767
Optimal placement of active elements in control augmented structural synthesis
Sepulveda, A. E.; Jin, I. M.; Schmit, L. A., Jr.
1992-01-01
A methodology for structural/control synthesis is presented in which the optimal location of active members is treated in terms of (0,1) variables. Structural member sizes, control gains and (0,1) placement variables are treated simultaneously as design variables. Optimization is carried out by generating and solving a sequence of explicit approximate problems using a branch and bound strategy. Intermediate design variable and intermediate response quantity concepts are used to enhance the quality of the approximate design problems. Numerical results for example problems are presented to illustrate the efficacy of the design procedure set forth.
Composite structure of wood cells in petrified wood
Nowak, Jakub [Department of Chemistry, Catholic University of Lublin, 20-718 Lublin (Poland); Florek, Marek [Department of Chemistry, Catholic University of Lublin, 20-718 Lublin (Poland); Kwiatek, Wojciech [Institute of Nuclear Physics, Department of Nuclear Spectroscopy, 31-342 Cracow (Poland); Lekki, Janusz [Institute of Nuclear Physics, Department of Nuclear Spectroscopy, 31-342 Cracow (Poland); Chevallier, Pierre [LPS, CEN Saclay et LURE, Universite Paris-Sud, Bat 209D, F-91405 Orsay (France); Zieba, Emil [Department of Chemistry, Catholic University of Lublin, 20-718 Lublin (Poland); Mestres, Narcis [Institut de Ciencia de Materials de Barcelona (ICMAB), Campus de la UAB, E-08193-Bellaterra (Spain); Dutkiewicz, E.M. [Institute of Nuclear Physics, Department of Nuclear Spectroscopy, 31-342 Cracow (Poland); Kuczumow, Andrzej [Department of Chemistry, Catholic University of Lublin, 20-718 Lublin (Poland)
2005-04-28
Special kinds of petrified wood of complex structure were investigated. All the samples were composed of at least two different inorganic substances. The original cell structure was preserved in each case. The remnants of the original biological material were detected in some locations, especially in the cell walls. The complex inorganic structure was superimposed on the remnant organic network. The first inorganic component was located in the lumena (l.) of the cells while another one in the walls (w.) of the cells. The investigated arrangements were as follows: calcite (l.)-goethite-hematite (w.)-wood from Dunarobba, Italy; pyrite (l.)-calcite (w.)-wood from Lukow, Poland; goethite (l.)-silica (w.)-wood from Kwaczala, Poland. The inorganic composition was analysed and spatially located by the use of three spectral methods: electron microprobe, X-ray synchrotron-based microprobe, {mu}-PIXE microprobe. The accurate mappings presenting 2D distribution of the chemical species were presented for each case. Trace elements were detected and correlated with the distribution of the main elements. In addition, the identification of phases was done by the use of {mu}-Raman and {mu}-XRD techniques for selected and representative points. The possible mechanisms of the described arrangements are considered. The potential synthesis of similar structures and their possible applications are suggested.
Analysis of morphological structuring elements generated using adaptive resonance theory
Sharpe, John P.; Sungar, Nilgun; Narayanswamy, Ramkumar; Johnson, Kristina M.
1995-03-01
In this paper we consider the formation of morphological templates using adaptive resonance theory. We examine the role of object variability and noise on the clustering of different sized objects as a function of the vigilance parameter. We demonstrate that the fuzzy adaptive resonance theory is robust in the presence of noise but that for poor choice of vigilance there is a proliferation of prototypical categories. We apply the technique to detection of abnormal cells in pap smears.
The correlation of structure elements of criminal procedural law
Khashieva Tanzila Magomedovna
2015-01-01
In this scientific article the author pays particular attention to the issue of classification of criminal procedure norms. The author determines the staging regulated by the norms subinstitutes and institutes of criminal procedure law activities as the main ground for the given variant of the structure of criminal procedure law.
Model Reduction in Dynamic Finite Element Analysis of Lightweight Structures
Flodén, Ola; Persson, Kent; Sjöström, Anders;
2012-01-01
The application of wood as a construction material when building multi-storey buildings has many advantages, e.g., light weight, sustainability and low energy consumption during the construction and lifecycle of the building. However, compared to heavy structures, it is a greater challenge to bui...
Xin-Gao Gong; Lihua Shen; Dier Zhang; Aihui Zhou
2008-01-01
In this paper, both the standard finite element discretization and a two-scale finite element discretization for SchrSdinger equations are studied. The numerical analysis is based on the regularity that is also obtained in this paper for the Schrodinger equations. Very satisfying applications to electronic structure computations are provided, too.
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.
Myriad Triple-Helix-Forming Structures in the Transposable Element RNAs of Plants and Fungi.
Tycowski, Kazimierz T; Shu, Mei-Di; Steitz, Joan A
2016-05-10
The ENE (element for nuclear expression) is a cis-acting RNA structure that protects viral or cellular noncoding RNAs (ncRNAs) from nuclear decay through triple-helix formation with the poly(A) tail or 3'-terminal A-rich tract. We expanded the roster of nine known ENEs by bioinformatic identification of ∼200 distinct ENEs that reside in transposable elements (TEs) of numerous non-metazoan and one fish species and in four Dicistrovirus genomes. Despite variation within the ENE core, none of the predicted triple-helical stacks exceeds five base triples. Increased accumulation of reporter transcripts in human cells demonstrated functionality for representative ENEs. Location close to the poly(A) tail argues that ENEs are active in TE transcripts. Their presence in intronless, but not intron-containing, hAT transposase genes supports the idea that TEs acquired ENEs to counteract the RNA-destabilizing effects of intron loss, a potential evolutionary consequence of TE horizontal transfer in organisms that couple RNA silencing to splicing deficits. PMID:27134163
A numerical implementation of a three-dimensional (3D) cellular automaton (CA)–finite element (FE) model has been developed for the prediction of solidification grain structures. For the first time, it relies on optimized parallel computation to solve industrial-scale problems (centimeter to meter long) while using a sufficiently small CA grid size to predict representative structures. Several algorithm modifications and strategies to maximize parallel efficiency are introduced. Improvements on a real case simulation are measured and discussed. The CA–FE implementation here is demonstrated using 32 computing units to predict grain structure in a 2.08 m × 0.382 m × 0.382 m ingot involving 4.9 billion cells and 1.6 million grains. These numerical improvements permit tracking of local changes in texture and grain size over real-cast parts while integrating interactions with macrosegregation, heat flow and fluid flow. Full 3D is essential in all these analyses, and can be dealt with successfully using the implementation presented here. (paper)
Ogitsu, Tadashi; Gygi, Francois; Reed, John; Schwegler, Eric; Galli, Giulia
2007-03-01
Boron exhibits the most complex structure of all elemental solids, with more than 300 atoms per unit cell arranged in interconnecting icosahedra, and some crystallographic positions occupied with a probability of less than one. The precise determination of the ground state geometry of boron---the so-called β-boron structure--has been elusive and its electronic and bonding properties have been difficult to rationalize. Using lattice model Monte Carlo optimization techniques and ab-initio simulations, we have shown that a defective, quasi-ordered β solid is the most stable structure at zero as well as finite T. In the absence of partially occupied sites (POS), the perfect β-boron crystal is unstable; the presence of POS lower its internal energy below that of an ordered α-phase, not mere an entropic effect. We present a picture of the intricate and unique bonding in boron based on maximally localized Wannier (MLWF) functions, which indicates that the presence of POS provides a subtle, yet essential spatial balance between electron deficient and fully saturated bonds. This work was performed under the auspices of the U.S. Dept. of Energy at the University of California/ LLNL under contract no. W-7405-Eng-48.
Bejing synchrotron radiation TXRF facility and its applications on trace element study of cells
In this paper, Beijing synchrotron radiation TXRF facility and experimental method were described. The minimum detection limits of some elements were tested by using several kinds of standard reference materials. The feasibility of using TXRF in biomedical field is discussed. With this technique small intestine cells of both normal and radiated white mice were analyzed, and the elemental average contents of each single cell are also given. The results indicated that the contents of some trace elements for normal and radiated white mice are greatly different, which may be used to provide valuable reference for clinic medicine. On the other hand, the trace elements of cells of lung and cervix cancer before and after apoptosis were determined by SRTXRF and the changes of trace elements in these cells were discussed. (author)
Probabilistic structural analysis using a general purpose finite element program
Riha, D. S.; Millwater, H. R.; Thacker, B. H.
1992-07-01
This paper presents an accurate and efficient method to predict the probabilistic response for structural response quantities, such as stress, displacement, natural frequencies, and buckling loads, by combining the capabilities of MSC/NASTRAN, including design sensitivity analysis and fast probability integration. Two probabilistic structural analysis examples have been performed and verified by comparison with Monte Carlo simulation of the analytical solution. The first example consists of a cantilevered plate with several point loads. The second example is a probabilistic buckling analysis of a simply supported composite plate under in-plane loading. The coupling of MSC/NASTRAN and fast probability integration is shown to be orders of magnitude more efficient than Monte Carlo simulation with excellent accuracy.
Behaviour and design of aluminium alloy structural elements
Su, Meini; 蘇玫妮
2014-01-01
Aluminium alloys are nonlinear metallic materials with continuous stress-strain curves that are not well represented by the simplified elastic, perfectly plastic material model used in most existing design specifications. The aims of this study are to develop a more efficient design method for aluminium alloy structures by rationally exploiting strain hardening. The key components of this study include laboratory testing, numerical modelling and development of design guidance for aluminium al...
Thermo-plastic finite element analysis for metal honeycomb structure
Ji Zhanling
2013-01-01
Full Text Available This paper deals with thermal-plastic analysis for the metal honeycomb structure. The heat transfer equation and thermal elastoplastic constitutive equation of a multilayer panel are established and studied numerically using ANSYS software. The paper elucidates that only the outer skin produces easily plastic deformation, and the outer skin still exists some residual stress and residual deformation after cooling. The dynamic evolution of plastic deformation and material performance degradation under high energy thermal load are revealed.
ON SHEAR BEHAVIOR OF STRUCTURAL ELEMENTS MADE OF STEEL FIBER REINFORCED CONCRETE
Cuenca Asensio, Estefanía
2013-01-01
Cuenca Asensio, E. (2012). ON SHEAR BEHAVIOR OF STRUCTURAL ELEMENTS MADE OF STEEL FIBER REINFORCED CONCRETE [Tesis doctoral no publicada]. Universitat Politècnica de València. doi:10.4995/Thesis/10251/18326. Palancia
Recognition on space photographs of structural elements of Baja California
Hamilton, W.
1971-01-01
Gemini and Apollo photographs provide illustrations of known structural features of the peninsula and some structures not recognized previously. An apparent transform relationship between strike-slip and normal faulting is illustrated by the overlapping vertical photographs of northern Baja California. The active Agua Blanca right-lateral strike-slip fault trends east-southeastward to end at the north end of the Valle San Felipe and Valle Chico. The uplands of the high Sierra San Pedro Martir are a low-relief surface deformed by young faults, monoclines, and warps, which mostly produce west-facing steps and slopes; the topography is basically structural. The Sierra Cucapas of northeasternmost Baja California and the Colorado River delta of northwesternmost Sonora are broken by northwest-trending strike-slip faults. A strike-slip fault is inferred to trend northward obliquely from near Cabo San Lucas to La Paz, thence offshore until it comes ashore again as the Bahia Concepcion strike-slip fault.
Finite element modeling of nanotube structures linear and non-linear models
Awang, Mokhtar; Muhammad, Ibrahim Dauda
2016-01-01
This book presents a new approach to modeling carbon structures such as graphene and carbon nanotubes using finite element methods, and addresses the latest advances in numerical studies for these materials. Based on the available findings, the book develops an effective finite element approach for modeling the structure and the deformation of grapheme-based materials. Further, modeling processing for single-walled and multi-walled carbon nanotubes is demonstrated in detail.
Haldimann, Matthias
2006-01-01
For centuries, the use of glass in buildings was essentially restricted to functions such as windows and glazing. Over the last decades, continuous improvements in production and refining technologies have enabled glass elements to carry more substantial superimposed loads and therefore achieve a more structural role. The structural design of such elements, however, remains problematic. Current widely used design methods suffer from notable shortcomings. They are, for instance, not applicable...
Vibration modeling of sandwich structures using solid-shell finite elements
KPEKY, Fessal; Boudaoud, Hakim; Chalal, Hocine; ABED-MERAIM, Farid; Daya, El Mostafa
2014-01-01
The aim of this work is to propose a new finite element modeling for vibration of sandwich structures with soft core. Indeed, several approaches have been adopted in the literature to accurately model these types of structures, but show some limitations in certain configurations of high contrast of material properties or geometric aspect ratios between the different layers. In these situations, it is generally well-known that the use of higher-order or three-dimensional finite elements is mor...
Moss cell walls: structure and biosynthesis
Alison W. Roberts; Eric M Roberts; Haigler, Candace H.
2012-01-01
The genome sequence of the moss Physcomitrella patens has stimulated new research examining the cell wall polysaccharides of mosses and the glycosyl transferases that synthesize them as a means to understand fundamental processes of cell wall biosynthesis and plant cell wall evolution. The cell walls of mosses and vascular plants are composed of the same classes of polysaccharides, but with differences in side chain composition and structure. Similarly, the genomes of P. patens and angiosperm...
Immersed smoothed finite element method for fluid-structure interaction simulation of aortic valves
Yao, Jianyao; Liu, G. R.; Narmoneva, Daria A.; Hinton, Robert B.; Zhang, Zhi-Qian
2012-12-01
This paper presents a novel numerical method for simulating the fluid-structure interaction (FSI) problems when blood flows over aortic valves. The method uses the immersed boundary/element method and the smoothed finite element method and hence it is termed as IS-FEM. The IS-FEM is a partitioned approach and does not need a body-fitted mesh for FSI simulations. It consists of three main modules: the fluid solver, the solid solver and the FSI force solver. In this work, the blood is modeled as incompressible viscous flow and solved using the characteristic-based-split scheme with FEM for spacial discretization. The leaflets of the aortic valve are modeled as Mooney-Rivlin hyperelastic materials and solved using smoothed finite element method (or S-FEM). The FSI force is calculated on the Lagrangian fictitious fluid mesh that is identical to the moving solid mesh. The octree search and neighbor-to-neighbor schemes are used to detect efficiently the FSI pairs of fluid and solid cells. As an example, a 3D idealized model of aortic valve is modeled, and the opening process of the valve is simulated using the proposed IS-FEM. Numerical results indicate that the IS-FEM can serve as an efficient tool in the study of aortic valve dynamics to reveal the details of stresses in the aortic valves, the flow velocities in the blood, and the shear forces on the interfaces. This tool can also be applied to animal models studying disease processes and may ultimately translate to a new adaptive methods working with magnetic resonance images, leading to improvements on diagnostic and prognostic paradigms, as well as surgical planning, in the care of patients.
Structured Extended Finite Element Methods of Solids Defined by Implicit Surfaces
Belytschko, T; Mish, K; Moes, N; Parimi, C
2002-11-17
A paradigm is developed for generating structured finite element models from solid models by means of implicit surface definitions. The implicit surfaces are defined by radial basis functions. Internal features, such as material interfaces, sliding interfaces and cracks are treated by enrichment techniques developed in the extended finite element method (X-FEM). Methods for integrating the weak form for such models are proposed. These methods simplify the generation of finite element models. Results presented for several examples show that the accuracy of this method is comparable to standard unstructured finite element methods.
Protein GB1 Folding and Assembly from Structural Elements
Sara Linse
2009-04-01
Full Text Available Folding of the Protein G B1 domain (PGB1 shifts with increasing salt concentration from a cooperative assembly of inherently unstructured subdomains to an assembly of partly pre-folded structures. The salt-dependence of pre-folding contributes to the stability minimum observed at physiological salt conditions. Our conclusions are based on a study in which the reconstitution of PGB1 from two fragments was studied as a function of salt concentrations and temperature using circular dichroism spectroscopy. Salt was found to induce an increase in β-hairpin structure for the C-terminal fragment (residues 41 – 56, whereas no major salt effect on structure was observed for the isolated N-terminal fragment (residues 1 – 41. In line with the increasing evidence on the interrelation between fragment complementation and stability of the corresponding intact protein, we also find that salt effects on reconstitution can be predicted from salt dependence of the stability of the intact protein. Our data show that our variant (which has the mutations T2Q, N8D, N37D and reconstitutes in a manner similar to the wild type displays the lowest equilibrium association constant around physiological salt concentration, with higher affinity observed both at lower and higher salt concentration. This corroborates the salt effects on the stability towards denaturation of the intact protein, for which the stability at physiological salt is lower compared to both lower and higher salt concentrations. Hence we conclude that reconstitution reports on molecular factors that govern the native states of proteins.
Non-linear finite element analysis in structural mechanics
Rust, Wilhelm
2015-01-01
This monograph describes the numerical analysis of non-linearities in structural mechanics, i.e. large rotations, large strain (geometric non-linearities), non-linear material behaviour, in particular elasto-plasticity as well as time-dependent behaviour, and contact. Based on that, the book treats stability problems and limit-load analyses, as well as non-linear equations of a large number of variables. Moreover, the author presents a wide range of problem sets and their solutions. The target audience primarily comprises advanced undergraduate and graduate students of mechanical and civil engineering, but the book may also be beneficial for practising engineers in industry.
ZHANG QianCheng; CHEN AiPing; CHEN ChangQing; LU TianJian
2009-01-01
The methods of homogenization and finite elements are employed to predict the effective elastic con-stants and stress-strain responses of a new type of lattice structure, the X-structure proposed by the authors in a companion paper. It is shown that in most cases the predictions by the equivalent ho-mogenization theory agree well with the experimental and 3-dimensional finite element calculated re-sults. The theoretical and numerical study supports the argument that the X-structure is superior to the pyramid lattice structure in terms of mechanical strength.
Ultralight X-type lattice sandwich structure (Ⅱ):Micromechanics modeling and finite element analysis
无
2009-01-01
The methods of homogenization and finite elements are employed to predict the effective elastic constants and stress-strain responses of a new type of lattice structure,the X-structure proposed by the authors in a companion paper. It is shown that in most cases the predictions by the equivalent homogenization theory agree well with the experimental and 3-dimensional finite element calculated results. The theoretical and numerical study supports the argument that the X-structure is superior to the pyramid lattice structure in terms of mechanical strength.
Structural evaluation of a nickel base super alloy metal foam via NDE and finite element
Abdul-Aziz, Ali; Abumeri, G.; Garg, Mohit; Young, P. G.
2008-03-01
Cellular materials are known to be useful in the application of designing light but stiff structures. This applies to various components used in various industries such as rotorcraft blades, car bodies or portable electronic devices. Structural application of the metal foam is typically confined to light weight sandwich panels, made up of thin solid face sheets and a metallic foam core. The resulting high-stiffness structure is lighter than that constructed only out of the solid metal material. The face sheets carry the applied in-plane and bending loads and the role of the foam core is separate the face sheets to carry some of the shear stresses, while remaining integral with the face sheet. Many challenges relating to the fabrication and testing of these metal foam panels continue to exist due to some mechanical properties falling short of their theoretical potential. Hence in this study, a detailed three dimensional foam structure is generated using series of 2D Computer Tomography (CT) scans, on Haynes 25 metal foam. Series of the 2D images are utilized to construct a high precision solid model including all the fine details within the metal foam as detected by the CT scanning technique. Subsequently, a finite element analysis is then performed on an as fabricated metal foam microstructures to evaluate the foam structural durability and behavior under tensile and compressive loading conditions. The analysis includes a progressive failure analysis (PFA) using GENOA code to further assess the damage initiation, propagation, and failure. The open cell metal foam material is a cobalt-nickel-chromium-tungsten alloy that combines excellent high-temperature strength with good resistance to oxidizing environments up to 1800 °F (980 °C) for prolonged exposures. The foam is formed by a powder metallurgy process with an approximate 100 pores per inch (PPI).
Cellular Structures in the Flow Over the Flap of a Two-Element Wing
Yon, Steven A.; Katz, Joseph
1997-01-01
Flow visualization information and time dependent pressure coefficients were recorded for the flow over a two-element wing. The investigation focused on the stall onset; particularly at a condition where the flow is attached on the main element but separated on the flap. At this condition, spanwise separation cells were visible in the flow over the flap, and time dependent pressure data was measured along the centerline of the separation cell. The flow visualizations indicated that the spanwise occurrence of the separation cells depends on the flap (and not wing) aspect ratio.
Wilt, T. E.
1995-01-01
The Generalized Method of Cells (GMC), a micromechanics based constitutive model, is implemented into the finite element code MARC using the user subroutine HYPELA. Comparisons in terms of transverse deformation response, micro stress and strain distributions, and required CPU time are presented for GMC and finite element models of fiber/matrix unit cell. GMC is shown to provide comparable predictions of the composite behavior and requires significantly less CPU time as compared to a finite element analysis of the unit cell. Details as to the organization of the HYPELA code are provided with the actual HYPELA code included in the appendix.
Stochastic Finite Element Analysis of Non-Linear Structures Modelled by Plasticity Theory
Frier, Christian; Sørensen, John Dalsgaard
2003-01-01
A Finite Element Reliability Method (FERM) is introduced to perform reliability analyses on two-dimensional structures in plane stress, modeled by non-linear plasticity theory. FERM is a coupling between the First Order Reliability Method (FORM) and the Finite Element Method (FEM). FERM can be used...... the structure, a discretisation into random elements/variables is introduced. To this purpose, both the Midpoint (MP) and the Spatial Average (SA) approach are considered. The failure probability is obtained iteratively based on a first order Taylor series expansion of the limit state function. Thus...
Structural basis of VDR–DNA interactions on direct repeat response elements
Shaffer, Paul L.; Gewirth, Daniel T.
2002-01-01
The vitamin D receptor (VDR) forms homo- or heterodimers on response elements composed of two hexameric half-sites separated by 3 bp of spacer DNA. We describe here the crystal structures at 2.7–2.8 Å resolution of the VDR DNA-binding region (DBD) in complex with response elements from three different promoters: osteopontin (SPP), canonical DR3 and osteocalcin (OC). These structures reveal the chemical basis for the increased affinity of VDR for the SPP response element, and for the poor stab...
Efficient Analysis of Structures with Rotatable Elements Using Model Order Reduction
G. Fotyga
2016-04-01
Full Text Available This paper presents a novel full-wave technique which allows for a fast 3D finite element analysis of waveguide structures containing rotatable tuning elements of arbitrary shapes. Rotation of these elements changes the resonant frequencies of the structure, which can be used in the tuning process to obtain the S-characteristics desired for the device. For fast commutations of the response as the tuning elements are rotated, the 3D finite element method is supported by multilevel model-order reduction, orthogonal projection at the boundaries of macromodels and the operation called macromodels cloning. All the time-consuming steps are performed only once in the preparatory stage. In the tuning stage, only small parts of the domain are updated, by means of a special meshing technique. In effect, the tuning process is performed extremely rapidly. The results of the numerical experiments confirm the efficiency and validity of the proposed method.
STARS: A general-purpose finite element computer program for analysis of engineering structures
Gupta, K. K.
1984-01-01
STARS (Structural Analysis Routines) is primarily an interactive, graphics-oriented, finite-element computer program for analyzing the static, stability, free vibration, and dynamic responses of damped and undamped structures, including rotating systems. The element library consists of one-dimensional (1-D) line elements, two-dimensional (2-D) triangular and quadrilateral shell elements, and three-dimensional (3-D) tetrahedral and hexahedral solid elements. These elements enable the solution of structural problems that include truss, beam, space frame, plane, plate, shell, and solid structures, or any combination thereof. Zero, finite, and interdependent deflection boundary conditions can be implemented by the program. The associated dynamic response analysis capability provides for initial deformation and velocity inputs, whereas the transient excitation may be either forces or accelerations. An effective in-core or out-of-core solution strategy is automatically employed by the program, depending on the size of the problem. Data input may be at random within a data set, and the program offers certain automatic data-generation features. Input data are formatted as an optimal combination of free and fixed formats. Interactive graphics capabilities enable convenient display of nodal deformations, mode shapes, and element stresses.
Cell Secretion: Current Structural and Biochemical Insights
Saurabh Trikha
2010-01-01
Full Text Available Essential physiological functions in eukaryotic cells, such as release of hormones and digestive enzymes, neurotransmission, and intercellular signaling, are all achieved by cell secretion. In regulated (calcium-dependent secretion, membrane-bound secretory vesicles dock and transiently fuse with specialized, permanent, plasma membrane structures, called porosomes or fusion pores. Porosomes are supramolecular, cup-shaped lipoprotein structures at the cell plasma membrane that mediate and control the release of vesicle cargo to the outside of the cell. The sizes of porosomes range from 150nm in diameter in acinar cells of the exocrine pancreas to 12nm in neurons. In recent years, significant progress has been made in our understanding of the porosome and the cellular activities required for cell secretion, such as membrane fusion and swelling of secretory vesicles. The discovery of the porosome complex and the molecular mechanism of cell secretion are summarized in this article.
Abdelal, Gasser F; Gad, Ahmed H
2013-01-01
Designing satellite structures poses an ongoing challenge as the interaction between analysis, experimental testing, and manufacturing phases is underdeveloped. Finite Element Analysis for Satellite Structures: Applications to Their Design, Manufacture and Testing explains the theoretical and practical knowledge needed to perform design of satellite structures. By layering detailed practical discussions with fully developed examples, Finite Element Analysis for Satellite Structures: Applications to Their Design, Manufacture and Testing provides the missing link between theory and implementation. Computational examples cover all the major aspects of advanced analysis; including modal analysis, harmonic analysis, mechanical and thermal fatigue analysis using finite element method. Test cases are included to support explanations an a range of different manufacturing simulation techniques are described from riveting to shot peening to material cutting. Mechanical design of a satellites structures are covered...
Morshed, Nader [University of California, Berkeley, CA 94720 (United States); Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Echols, Nathaniel, E-mail: nechols@lbl.gov [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Adams, Paul D., E-mail: nechols@lbl.gov [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); University of California, Berkeley, CA 94720 (United States)
2015-05-01
A method to automatically identify possible elemental ions in X-ray crystal structures has been extended to use support vector machine (SVM) classifiers trained on selected structures in the PDB, with significantly improved sensitivity over manually encoded heuristics. In the process of macromolecular model building, crystallographers must examine electron density for isolated atoms and differentiate sites containing structured solvent molecules from those containing elemental ions. This task requires specific knowledge of metal-binding chemistry and scattering properties and is prone to error. A method has previously been described to identify ions based on manually chosen criteria for a number of elements. Here, the use of support vector machines (SVMs) to automatically classify isolated atoms as either solvent or one of various ions is described. Two data sets of protein crystal structures, one containing manually curated structures deposited with anomalous diffraction data and another with automatically filtered, high-resolution structures, were constructed. On the manually curated data set, an SVM classifier was able to distinguish calcium from manganese, zinc, iron and nickel, as well as all five of these ions from water molecules, with a high degree of accuracy. Additionally, SVMs trained on the automatically curated set of high-resolution structures were able to successfully classify most common elemental ions in an independent validation test set. This method is readily extensible to other elemental ions and can also be used in conjunction with previous methods based on a priori expectations of the chemical environment and X-ray scattering.
Phillips, A T M; Villette, C.; Modenese, L.
2015-01-01
Through much of the anatomical and clinical literature bone is studied with a focus on its structural architecture, while it is rare for bone to be modelled using a structural mechanics as opposed to a continuum mechanics approach in the engineering literature. A novel mesoscale structural model of the femur is presented in which truss and shell elements are used to represent trabecular and cortical bone, respectively. Structural optimisation using a strain-based bone adaptation algorithm is ...
Application of ADINA fluid element for transient response analysis of fluid-structure system
Pressure propagation and Fluid-Structure Interaction (FSI) in 3D space were simulated by general purpose finite element program ADINA using the displacement-based fluid element which presumes inviscid and compressible fluid with no net flow. Numerical transient solution was compared with the measured data of an FSI experiment and was found to fairly agree with the measured. In the next step, post analysis was conducted for a blowdown experiment performed with a 1/7 scaled reactor pressure vessel and a flexible core barrel and the code performance was found to be satisfactory. It is concluded that the transient response of the core internal structure of a PWR during the initial stage of LOCA can be analyzed by the displacement-based finite fluid element and the structural element. (orig.)
Structural elements regulating amyloidogenesis: a cholinesterase model system.
Létitia Jean
Full Text Available Polymerization into amyloid fibrils is a crucial step in the pathogenesis of neurodegenerative syndromes. Amyloid assembly is governed by properties of the sequence backbone and specific side-chain interactions, since fibrils from unrelated sequences possess similar structures and morphologies. Therefore, characterization of the structural determinants driving amyloid aggregation is of fundamental importance. We investigated the forces involved in the amyloid assembly of a model peptide derived from the oligomerization domain of acetylcholinesterase (AChE, AChE(586-599, through the effect of single point mutations on beta-sheet propensity, conformation, fibrilization, surfactant activity, oligomerization and fibril morphology. AChE(586-599 was chosen due to its fibrilization tractability and AChE involvement in Alzheimer's disease. The results revealed how specific regions and residues can control AChE(586-599 assembly. Hydrophobic and/or aromatic residues were crucial for maintaining a high beta-strand propensity, for the conformational transition to beta-sheet, and for the first stage of aggregation. We also demonstrated that positively charged side-chains might be involved in electrostatic interactions, which could control the transition to beta-sheet, the oligomerization and assembly stability. Further interactions were also found to participate in the assembly. We showed that some residues were important for AChE(586-599 surfactant activity and that amyloid assembly might preferentially occur at an air-water interface. Consistently with the experimental observations and assembly models for other amyloid systems, we propose a model for AChE(586-599 assembly in which a steric-zipper formed through specific interactions (hydrophobic, electrostatic, cation-pi, SH-aromatic, metal chelation and polar-polar would maintain the beta-sheets together. We also propose that the stacking between the strands in the beta-sheets along the fiber axis could
Effect of Large Negative Phase of Blast Loading on Structural Response of RC Elements
Syed Zubair Iman
2016-01-01
Full Text Available Structural response of reinforced concrete (RC elements for analysis and design are often obtained using the positive phase of the blast pressure curve disregarding the negative phase assuming insignificant contribution from the negative phase of the loading. Although, some insight on the effect of negative phase of blast pressure based on elastic single-degree-of-freedom (SDOF analysis was presented before, the influence of negative phase on different types of resistance functions of SDOF models and on realistic finite element analysis has not been explored. In this study, the effects of inclusion of pulse negative phase on structural response of RC elements from SDOF analysis and from more detailed finite element analysis have been investigated. Investigation of SDOF part has been conducted using MATLAB code that utilizes non-linear resistance functions of SDOF model. Detailed numerical investigation using finite element code DIANA was conducted on the significance of the negative phase on structural response. In the FE model, different support stiffness was used to explore the effect of support stiffness on the structural response due to blast negative phase. Results from SDOF and FE analyses present specific situations where the effect of large negative phase was found to be significant on the structural response of RC elements.
Advanced Design of Composite Steel-Concrete Structural element
Dr. D. R. Panchal
2014-07-01
Full Text Available Composite framing system consisting of steel beams acting interactively with metal deck-concrete slab and concrete encased composite columns, has been as a viable alternative to the conventional steel or reinforced concrete system in the high-rise construction. However, in Indian context, it is comparatively new and no appropriate design codes are available for the same. Complications in the analysis and design of composite structures have led numerous researchers to develop simplified methods so as to eliminate a number of large scale tests needed for the design. In the present work, a simplified method of composite slabs, beams and columns design is used and software is developed with pre- and post- processing facilities in VB.NET. All principal design checks are incorporated in the software. The full and partial shear connection and the requirement for transverse reinforcement are also considered. To facilitate direct selection of steel section, a database is prepared and is available at the back end with the properties of all standard steel sections. Screen shots are included in the paper to illustrate the method employed for selecting the appropriate section and shear connectors and thus to verify the design adequacy.
Finite element modeling of composite piezoelectric structures with MSC/NASTRAN
Freed, Brian D.; Babuska, Vit
1997-06-01
Techniques for modeling structures containing piezoelectric ceramics with MSC/NASTRAN are presented. Unlike other finite element programs such as ANSYS and ABAQUS, MSC/NASTRAN offers no piezoelectric coupled-field elements with which to model smart structures directly. Rather, the analogy between piezoelectric strain and thermally induced strain, which allows temperature change to model piezoelectric voltage actuation, must be used. The application and limitations of this method are discussed. To overcome some of the limitations in modeling piezoelectric effects with the thermal analogy, one and two dimensional finite elements which include piezoelectric coupling were developed and integrated into MSC/NASTRAN as dummy elements. The dummy elements offer an alternative method for modeling piezoelectric structural members. As actuators, the elements support charge and voltage actuation in both static and dynamic analyses. When used as sensors, both strain and strain rate outputs are supported. The elements can be used for modal, transient, and frequency response solutions and facilitate combined thermal and piezoelectric loading.
Kinematics and dynamics of deployable structures with scissor-like-elements based on screw theory
Sun, Yuantao; Wang, Sanmin; Mills, James K.; Zhi, Changjian
2014-07-01
Because the deployable structures are complex multi-loop structures and methods of derivation which lead to simpler kinematic and dynamic equations of motion are the subject of research effort, the kinematics and dynamics of deployable structures with scissor-like-elements are presented based on screw theory and the principle of virtual work respectively. According to the geometric characteristic of the deployable structure examined, the basic structural unit is the common scissor-like-element(SLE). First, a spatial deployable structure, comprised of three SLEs, is defined, and the constraint topology graph is obtained. The equations of motion are then derived based on screw theory and the geometric nature of scissor elements. Second, to develop the dynamics of the whole deployable structure, the local coordinates of the SLEs and the Jacobian matrices of the center of mass of the deployable structure are derived. Then, the equivalent forces are assembled and added in the equations of motion based on the principle of virtual work. Finally, dynamic behavior and unfolded process of the deployable structure are simulated. Its figures of velocity, acceleration and input torque are obtained based on the simulate results. Screw theory not only provides an efficient solution formulation and theory guidance for complex multi-closed loop deployable structures, but also extends the method to solve dynamics of deployable structures. As an efficient mathematical tool, the simper equations of motion are derived based on screw theory.
A finite element analysis of a 3D auxetic textile structure for composite reinforcement
This paper reports the finite element analysis of an innovative 3D auxetic textile structure consisting of three yarn systems (weft, warp and stitch yarns). Different from conventional 3D textile structures, the proposed structure exhibits an auxetic behaviour under compression and can be used as a reinforcement to manufacture auxetic composites. The geometry of the structure is first described. Then a 3D finite element model is established using ANSYS software and validated by the experimental results. The deformation process of the structure at different compression strains is demonstrated, and the validated finite element model is finally used to simulate the auxetic behaviour of the structure with different structural parameters and yarn properties. The results show that the auxetic behaviour of the proposed structure increases with increasing compression strain, and all the structural parameters and yarn properties have significant effects on the auxetic behaviour of the structure. It is expected that the study could provide a better understanding of 3D auxetic textile structures and could promote their application in auxetic composites. (paper)
Two refined axisymmetric finite element models were used for the dynamic seismic analyses of the KKP-II Containment and RPV structures, using a postulated ground motion time history. One model was established primarily for the response of the containment structure, whereas the other was used for the response of the reactor pressure vessel plus internals. (Auth.)
Structural and Functional Studies of the Promoter Element for Dengue Virus RNA Replication ▿
Lodeiro, María F.; Filomatori, Claudia V.; Andrea V Gamarnik
2008-01-01
The 5′ untranslated region (5′UTR) of the dengue virus (DENV) genome contains two defined elements essential for viral replication. At the 5′ end, a large stem-loop (SLA) structure functions as the promoter for viral polymerase activity. Next to the SLA, there is a short stem-loop that contains a cyclization sequence known as the 5′ upstream AUG region (5′UAR). Here, we analyzed the secondary structure of the SLA in solution and the structural requirements of this element for viral replicatio...
Structural variations in aromatic 2-electron three-membered rings of the main group elements
Dibyendu Mallick; Eluvathingal D Jemmis
2015-02-01
Structural variations of different 2-aromatic three-membered ring systems of main group elements, especially group 14 and 13 elements as compared to the classical description of cyclopropenyl cation has been reviewed in this article. The structures of heavier analogues as well as group 13 analogues of cyclopropenyl cation showed an emergence of dramatic structural patterns which do not conform to the generalnorms of carbon chemistry. Isolobal analogies between the main group fragments have been efficiently used to explain the peculiarities observed in these three-membered ring systems.
Finite element simulation of mechanical behaviour of nickel-based metallic foam structures
Kaoua, Sid-Ali; Dahmoun, Djaffar; Belhadj, Abd-Elmouneim [Laboratoire des Sciences et de Genie des Materiaux (LSGM), Universite des Sciences et de la Technologie Houari Boumediene (USTHB), BP 32 El-Allia, 16111 Bab Ezzouar, Algiers (Algeria); Azzaz, Mohammed [Laboratoire des Sciences et de Genie des Materiaux (LSGM), Universite des Sciences et de la Technologie Houari Boumediene (USTHB), BP 32 El-Allia, 16111 Bab Ezzouar, Algiers (Algeria)], E-mail: azzaz@wissal.dz
2009-03-05
In this paper, numerical simulation by finite elements is performed in order to study the mechanical behaviour of foam structures subjected to tension loading. The anisotropic cellular model of Gibson and Ashby is taken like reference in our simulation. The foam structure, constituted by struts and connection stems, is modelled by space beam finite elements. This led to a parametric analysis showing the evolution of foam Young modulus according to some geometrical parameters of the cellular network structure, such as shape and dimensions of cross-section, connection stem length.
Finite element simulation of mechanical behaviour of nickel-based metallic foam structures
In this paper, numerical simulation by finite elements is performed in order to study the mechanical behaviour of foam structures subjected to tension loading. The anisotropic cellular model of Gibson and Ashby is taken like reference in our simulation. The foam structure, constituted by struts and connection stems, is modelled by space beam finite elements. This led to a parametric analysis showing the evolution of foam Young modulus according to some geometrical parameters of the cellular network structure, such as shape and dimensions of cross-section, connection stem length
Molecules and Models The molecular structures of main group element compounds
Haaland, Arne
2008-01-01
This book provides a systematic description of the molecular structures and bonding in simple compounds of the main group elements with particular emphasis on bond distances, bond energies and coordination geometries. The description includes the structures of hydrogen, halogen and methyl derivatives of the elements in each group, some of these molecules are ionic, some polar covalent. The survey of molecules whose structures conform to well-established trends is followed byrepresentative examples of molecules that do not conform. We also describe electron donor-acceptor and hydrogen bonded co
Domadiya, Parthkumar Gandalal; Dickow, Kristoffer Ahrens; Andersen, Lars;
2011-01-01
This paper concerns the analysis of noise transmission in a lightweight panel structure. The analysis is based on Finite Element Analysis (FEA) employing solid elements for the structure. The analysis focuses on flanking noise transmission in panel structures of finite size. A parametric study is...... and different designs of the ribs regarding the energy contained within the panel strip. The paper presents an analysis of vibrational energy transmission for an isotropic periodic panel strip excited by a concentrated force. The computations are carried out in frequency domain in the range below 2 kHz....
GEOMETRICALLY NONLINEAR FE FORMULATIONS FOR THE MACRO-ELEMENT UNIPLET OF FOLDABLE STRUCTURES
陈务军; 付功义; 何艳丽; 董石麟
2002-01-01
Geometrically nonlinear stiffness matrix due to large displacement-small strain was firstly formulated ex-plicitly for the basic components of pantographic foldable structures,namely, the uniplet, derived from a three-node beam element. The formulation of the uniplet stiffness matrix is based on the precise nonlinear finite elementtheory and the displacement-harmonized and internal force constraints are applied directly to the deformationmodes of the three-node beam element. The formulations were derived in general form, and can be simplified forparticular foldable structures, such as flat, cylindrical and spherical structures. Finally, two examples were pre-sented to illustrate the applications of the stiffness matrix evolved.