bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of melatonin and caffeic acid phenethyl ester on testicular injury induced by myocardial ischemia/reperfusion in rats
Authors: Eşrefoğlu Mukaddes , Gül Mehmet , Parlakpinar Hakan , Acet Ahmet
Published: June 2005

Experimental studies indicate that ischemia/reperfusion (I/R) causes remote organ injury although the molecular mechanism has not been clearly defined. In this report, the role of oxidative injury on testicular damage following myocardial I/R injury and the effects of antioxidant agents, melatonin and caffeic acid phenethyl ester (CAPE), on testicular injury were investigated. As far as we know, this is the first report demonstrating that myocardial I/R induces damage to the testes. Thirty‐two male Wistar rats were randomly divided into four groups: sham operation (SO), I/R + vehicle, I/R + melatonin, and I/R + caffeic acid phenethyl ester. To produce cardiac damage, the left main coronary artery was occluded for 30 min, followed by 120 min reperfusion, in anesthetized rats. Serum nitric oxide (NO) and malondialdehyde (MDA) levels and morphological changes were examined. I/R was accompanied by a significant increase in serum MDA and NO levels, whereas, melatonin and CAPE administration significantly reduced these values. Melatonin was more efficient in reducing MDA levels than CAPE (P < 0.05). I/R induced myocardial damage, manifested as the histopathological evidence of intracellular vacuolization, interstitial edema, neutrophil infiltration and coagulative necrosis. I/R + vehicle group showed many histological alterations such as focal tubular atrophy, and degeneration and disorganization of the seminiferous epithelium in testes. The number of atrophic tubules and degenerating cells was significantly higher in I/R + vehicle group than that of SO group. Melatonin and CAPE significantly reduced the number of degenerating cells; additionally, melatonin reduced the number of atrophic tubules (P < 0.05). Our results indicate that myocardial I/R induces severe testicular damage and antioxidant agents, especially melatonin, have protective effects on testicular injury after myocardial I/R. Our data emphasize that oxygen‐based reactants may play a central role in remote organ injury.
Impaired α1‐adrenergic responses in aged rat hearts
Authors: Montagne Olivier , Corvoisier Philippe Le , Guenoun Thierry , Laplace Monique , Crozatier Bertrand
Published: June 2005

To determine age‐related changes in the cardiac effect of α1‐adrenergic stimulation, both cardiomyocyte Ca2+‐transient and cardiac protein kinase C (PKC) activity were measured in 3‐month‐ (3MO) and 24‐month‐ (24MO) old Wistar rats. Ca2+ transients obtained under 1 Hz pacing by microfluorimetry of cardiomyocyte loaded with indo‐1 (405/480 nm fluorescence ratio) were compared in control conditions (Kreb's solution alone) and after α1‐adrenergic stimulation (phenylephrine or cirazoline, an α1‐specific agonist). PKC activity and PKC translocation index (particulate/total activity) were also assayed before and after α1‐adrenergic stimulation. In 3MO, cirazoline induced a significant increase in Ca2+ transient for a 10−9 m concentration which returned to control values for larger concentrations. In contrast, in 24MO, we observed a constant negative effect of cirazoline on the Ca2+ transient with a significant decrease at 10−6 m compared with both baseline and Kreb's solution. Preliminary experiments showed that, in a dose–response curve to phenylephrine, the response of Ca2+ transient was maximal at 10−7 m. This concentration induced a significant increase in Ca2+ transient in 3MO and a significant decrease in 24MO. The same concentration was chosen to perform PKC activity measurements under α1‐adrenergic stimulation. In the basal state, PKC particulate activity was higher in 24MO than that in 3MO but was not different in cytosolic fractions; so that the translocation index was higher in 24MO (P < 0.01). After phenylephrine, a translocation of PKC toward the particulate fraction was observed in 3MO but not in 24MO. In conclusion, cardiac α1‐adrenoceptor response was found to be impaired in aged hearts. The negative effect of α1‐adrenergic stimulation on Ca2+ transient in cardiomyocytes obtained from old rats can be related to an absence of α1‐adrenergic‐induced PKC translocation.
Effects of ouabain on contractions induced by manganese ions in Ca2+‐free, isotonic solutions with varying concentrations of K+ in guinea‐pig taenia coli
Authors: Nasu Tetsuyuki , Takahashi Katsunori
Published: June 2005

The action of ouabain, a cell membrane Na+, K+‐ATPase blocker, on contractions induced by manganese ions (Mn2+) in Ca2+‐free, isotonic solutions with varying concentrations of K+ in the external medium were investigated in order to evaluate the underlying role of external Na+ in Mn2+‐induced contractions in isolated taenia coli of the guinea‐pig. Mn2+ at 5 mm induced greater contractions as external isotonic K+ concentrations progressively increased from 10 to 100 mm. Ouabain (2 × 10−4 m) completely inhibited tension development stimulated by 5 mm Mn2+ in isotonic, 30 mm K+ (96 mm Na+) medium. Whereas, the tension inhibitory effects of ouabain became progressively weaker as isotonic, external K+ concentrations increased to 60 mm, which successively decreased external Na+ concentrations. Eventually, ouabain failed to affect contractions stimulated by Mn2+ in isotonic, 126 mm K+, Na+‐deficient medium. Ouabain caused progressively greater increase in cellular Na+ concentrations as the Na+ concentrations increased in the isotonic, K+ medium. While, pyruvate, which penetrates cell independently of external Na+, reversed the inhibition of tension by ouabain in isotonic, 30 mm K+, Na+‐sufficient (96 mm) medium containing 5 mm Mn2+. These results suggested that Mn2+ induced the contraction, which was maintained by glucose transport depending on external Na+, in the case of Na+‐sufficient medium in K+‐depolarized taenia coli. However, it induced the contraction independent of external Na+, in the case of Na+‐deficient, K+ medium. Ouabain might exhibit greater inhibition of the contraction induced by Mn2+ as the decrease in the Na+ gradient across the cell membranes continues.
Translocation Biosensors to Study Signal‐Specific Nucleo‐Cytoplasmic Transport, Protease Activity and Protein–Protein Interactions
Authors: Knauer Shirley K. , Moodt Sabrina , Berg Thorsten , Liebel Urban , Pepperkok Rainer , Stauber Roland H.
Published: June 2005

Regulated nucleo‐cytoplasmic transport is crucial for cellular homeostasis and relies on protein interaction networks. In addition, the spatial division into the nucleus and the cytoplasm marks two intracellular compartments that can easily be distinguished by microscopy. Consequently, combining the rules for regulated nucleo‐cytoplasmic transport with autofluorescent proteins, we developed novel cellular biosensors composed of glutathione S‐transferase, mutants of green fluorescent protein and rational combinations of nuclear import and export signals. Addition of regulatory sequences resulted in three classes of biosensors applicable for the identification of signal‐specific nuclear export and import inhibitors, small molecules that interfere with protease activity and compounds that prevent specific protein–protein interactions in living cells. As a unique feature, our system exploits nuclear accumulation of the cytoplasmic biosensors as the reliable readout for all assays. Efficacy of the biosensors was systematically investigated and also demonstrated by using a fully automated platform for high throughput screening (HTS) microscopy and assay analysis. The introduced modular biosensors not only have the potential to further dissect nucleo‐cytoplasmic transport pathways but also to be employed in numerous screening applications for the early stage evaluation of potential drug candidates.
The Cell Biology of Hermansky–Pudlak Syndrome: Recent Advances
Authors: Di Pietro Santiago M. , Dell'Angelica Esteban C.
Published: June 2005

Hermansky–Pudlak syndrome (HPS) defines a group of at least seven autosomal recessive disorders characterized by albinism and prolonged bleeding. These manifestations arise from defects in the biogenesis of lysosome‐related organelles, including melanosomes and platelet dense granules. Most genes associated with HPS in humans and rodent models of the disease encode components of multisubunit protein complexes that are expressed ubiquitously and play roles in intracellular protein trafficking and/or organelle distribution. A small GTPase of the Rab family, Rab38, is also implicated in the pathogenesis of the disease. This article reviews recent progress toward elucidating the cellular functions of these proteins.
Verprolin Cytokinesis Function Mediated by the Hof One Trap Domain
Authors: Ren Gang , Wang Juan , Brinkworth Ross , Winsor Barbara , Kobe Bostjan , Munn Alan L.
Published: June 2005

In budding yeast, partitioning of the cytoplasm during cytokinesis can proceed via a pathway dependent on the contractile actomyosin ring, as in other eukaryotes, or alternatively via a septum deposition pathway dependent on an SH3 domain protein, Hof1/Cyk2 (the yeast PSTPIP1 ortholog). In dividing yeast cells, Hof1 forms a ring at the bud neck distinct from the actomyosin ring, and this zone is active in septum deposition. We previously showed the yeast Wiskott–Aldrich syndrome protein (WASP)‐interacting protein (WIP) ortholog, verprolin/Vrp1/End5, interacts with Hof1 and facilitates Hof1 recruitment to the bud neck. A Vrp1 fragment unable to interact with yeast WASP (Las17/Bee1), localize to the actin cytoskeleton or function in polarization of the cortical actin cytoskeleton nevertheless retains function in Hof1 recruitment and cytokinesis. Here, we show the ability of this Vrp1 fragment to bind the Hof1 SH3 domain via its Hof one trap (HOT) domain is critical for cytokinesis. The Vrp1 HOT domain consists of three tandem proline‐rich motifs flanked by serines. Unexpectedly, the Hof1 SH3 domain itself is not required for cytokinesis and indeed appears to negatively regulate cytokinesis. The Vrp1 HOT domain promotes cytokinesis by binding to the Hof1 SH3 domain and counteracting its inhibitory effect.
The CHiPS Domain – Ancient Traces for the Hermansky–Pudlak Syndrome
Authors: Hoffman‐Sommer Marta , Grynberg Marcin , Kucharczyk Roza , Rytka Joanna
Published: June 2005

Hermansky–Pudlak syndrome (HPS) is a rare disorder caused by malfunctions of lysosomes and specialized lysosome‐related organelles, resulting primarily in oculocutaneous albinism and bleeding diathesis. The majority of the HPS genes have been described as novel, but herein we report the identification of a conserved protein family which includes human HPS4, as well as distant homologs for other HPS genes. Our results suggest that the cellular machinery involved in the HPS syndrome is ancient.
Bioceramic Bone Graft Substitutes: Influence of Porosity and Chemistry
Authors: Hing Karin A.
Published: June 2005

Bioceramics have been considered for use as synthetic bone graft substitutes (BGSs) for over 30 years, throughout which there have been two primary areas of research: (i) optimization of the physical pore structure and (ii) formulation of an appropriate bioceramic chemistry. While it is well recognized that both the rate of integration and the final volume of regenerated bone are primarily dependent on the macroporosity, there still seems to be some dispute regarding the optimum “type” of porosity. The rate and quality of bone integration have, in turn, been related to a dependence on pore size, porosity volume fraction, and interconnection size and interconnection density, both as a function of structural permeability and mechano‐transduction. Moreover, the role of strut microstructure and pore geometry have been considered with respect to their influence on entrapment and recruitment of growth factors (GFs) in addition to its influence on scaffold mechanics. Deconvoluting the relative affects of these parameters is complicated by the use of both resorbable and nonresorbable bioactive bioceramics, which are believed to mediate bioactivity in the osseous environment through two principal mechanisms: (i) directly through dissolution and release of ionic products in vivo, elevating local concentrations of soluble species that interact directly with local cells or influence cell behavior by their effect on local pH, (ii) indirectly through the influence that surface chemistry will have on protein adsorption, GF entrapment, and subsequent cell attachment and function. This article aims to review some of the recent developments in bioceramic BGSs, with a view to understanding how the various physiochemical parameters may be optimized to promote bone healing.
Ceramic Microspheres for Biomedical Applications
Authors: Kawashita Masakazu
Published: June 2005

Ceramic microspheres are expected to be useful for cancer treatment and antibacterial treatment. In this article, several attempts to prepare ceramic microspheres for such biomedical applications are described. Ceramic microspheres containing large amounts of yttrium or phosphorus are useful for radiotherapy of cancers, since they can be activated to become β‐emitters by neutron bombardment. Ferrimagnetic microspheres are useful as thermoseeds for hyperthermia of cancers because they can heat cancers locally by hysteresis loss of the ferrimagnetic materials under an alternating magnetic field. Silver‐containing silica glass microspheres are useful as antibacterial materials when mixed with organic polymers, particularly fine‐spun polymer fibers.
Plastic Deformation of Hydroxyapatites and Its Application to Joining
Authors: Singh D. , De La Cinta Lorenzo‐Martin M. , Routbort J. L. , Gutiérrez‐Mora F. , Case E. D.
Published: June 2005

A plastic deformation process was demonstrated to self‐join hydroxyapatite (HA), fabricating pore‐free joints at 1275°C at a strain rate of 10−5 s−1. To determine optimum joining conditions, high‐temperature compressive deformation of HA was investigated for strain rates between 5 × 10−6 and 10−4 s−1 at temperatures 1175–1275°C. X‐ray diffraction revealed primarily the HA phase with the presence of tri‐ and tetra‐calcium phosphate phases. Steady‐state flow stresses were 0.6–45 MPa and increased with increasing strain rates. Stress exponents of ≈1 indicated a viscous diffusion‐controlled deformation mechanism with an activation energy of ≈354±36 kJ/mol. Absence of cavitation and grain shape changes was consistent with grain boundary sliding.
Oxidation Microstructures and Interfaces in the Oxidized Zirconium Knee
Authors: Hobbs Linn W. , Rosen Valarie Benezra , Mangin Stephan P. , Treska Meri , Hunter Gordon
Published: June 2005

This contribution describes the microstructural development of a predominantly zirconia scale resulting from thermal oxidation of a Zr–2.65 wt% Nb alloy that is used to provide a superior resilient bearing surface on the femoral condylar component in a novel total knee prosthesis. The oxide scale exhibits superior tribological properties articulating against a polyethylene tibial component, resulting in substantially reduced wear debris and attendant inflammatory response. Critical attributes of this scale are biological compatibility, hardness, maintenance of surface smoothness during articulation, and adhesion to the substrate. Thermogravimetry, transmission electron microscopy, and in situ hot‐stage X‐ray diffraction analyses of the oxide scale and underlying alloy substrate were employed to reveal the microstructural origins for the efficacy and integrity of this oxidation surface treatment. The wrought alloy in the condylar component exhibits a two‐phase microstructure comprising elongated hexagonal α‐Zr grains (<1 wt% Nb) discontinuously surrounded by cubic β‐Zr (∼18 wt% Nb) sheath grains. During oxidation for times up to 8 h in air at temperatures above and below the eutectoid at 620°C, interface control of oxidation kinetics occurs at an alloy/scale interface that advances into the alloy by inward oxygen diffusion. The oxide scale predominantly comprises columnar grains of monoclinic ZrO2, ∼40 nm wide × 200 nm long, with [001]m and [111]m fiber textures and arranged in a brickwork pattern that is highly resistant to lateral fracture and surface grain pull‐out that would compromise scale integrity and function. The scale forms under substantial compression, up to nearly −2 GPa in the surface plane throughout the oxidation, and maintains its compressive state when cooling down to room temperature. At the scale/alloy interface, unoxidized Nb stringers in oxidizing β‐Zr second‐phase grains extend from the alloy into the oxide scale and appear to anchor the scale to the alloy, accounting for the excellent scale adhesion observed. Further oxidation of the β‐Zr second phase farther into the scale is associated with isolated outcrops of equiaxed oxide enhanced in segregated Nb content. Nearer the scale/air interface, lathlike separation into Zr‐rich and Nb‐rich oxides and lamellar intergrowths of a mixed‐oxide phase (probably 6ZrO2·Nb2O5) occur but do not appear deleterious to the integrity or functionality of the scale, especially as the outermost portion of the scale is removed in establishing the final bearing surface of the commercial prosthesis.
Customization of Load‐Bearing Hydroxyapatite Lattice Scaffolds
Authors: Cesarano Joseph , Dellinger Jennifer G. , Saavedra Michael P. , Gill David D. , Jamison Russell D. , Grosser Benjamin A. , Sinn‐Hanlon Janet M. , Goldwasser Michael S.
Published: June 2005

Robocasting, a solid freeform fabrication technique, was used to develop lattices of hydroxyapatite (HA) that show promise as load‐bearing scaffolds for bone repair. Additionally, the lattice scaffolds can be shaped into customized implants. A computed tomography (CT) scan of a damaged mandible was utilized to noninvasively design a lattice implant that could fill the damaged region. In a case study, the fit of the custom lattice scaffold was tested in a damaged mandible and “fit like a glove.” Such implants may be able to replace numerous autograft procedures, thereby reducing surgical cost and complications associated with bone harvesting surgery.
Temperature Distribution and Thermal Stress Analysis of Ball-Tank Subjected to Solar Radiation
Authors: Verma Vishnu , Ghosh A. K. , Kushwaha H. S.
Published: June 2005

The ball tank of the research reactor CIRUS is exposed to solar radiation. The ambient temperature undergoes seasonal and diurnal variation. The resulting thermal stress could be significant for the large structure. The temperature distribution has been obtained by the finite element method. The paper presents temperature distribution and the resulting thermal stress.
Optimum Global Failure Prediction Model of Steam Generator Tube With Two Parallel Axial Through-Wall Cracks
Authors: Moon Seong-In , Kim Young-Jin , Lee Jin-Ho , Song Myung-Ho , Park Youn-Won
Published: June 2005

The 40% of wall criterion, which is generally used for the plugging of steam generator tubes, is applied only to a single crack. In the previous study (Moon et al. (2002)), a total number of 9 failure models were introduced to estimate the local failure of the ligament between cracks and the optimum coalescence model of multiple collinear cracks was determined among these models. It is, however, known that parallel axial cracks are more frequently detected during an in-service inspection than collinear axial cracks. The objective of this study is to determine the plastic collapse model which can be applied to the steam generator tube containing two parallel axial through-wall cracks. Three previously proposed local failure models were selected as the candidates. Subsequently interaction effects between two adjacent cracks were evaluated to screen them. Plastic collapse tests for the plate with two parallel through-wall cracks and finite element analyses were performed for the determination of the optimum plastic collapse model. By comparing the test results with the prediction results obtained from the candidate models, a crack opening displacement (COD) base model was selected as an optimum model.
Effects of Flow–Pipe Interaction on Drill Pipe Buckling and Dynamics
Authors: Zhang Qun , Miska Stefan
Published: June 2005

A theoretical study has been performed on the buckling and lateral vibration of drillpipe interacted with incompressible fluid in vertical holes. Particular attention is paid to the flow–pipe interaction near drillpipe neutral zone. A new theoretical model has been established. The flow–pipe interaction forces are characterized in this model. Dimensional analysis has been conducted to generalize this model. An innovative numerical method has been developed to solve the eigensystem. Several numerical examples are provided to show the effects of flow–pipe interaction on drillpipe buckling and dynamics. Results show that drilling fluid has significant hydrodynamic influence on drillpipe statics and dynamics.
Integrity Assessment of Pressure Components With Local Hot Spots
Authors: Seshadri R.
Published: June 2005

Local hot spots can occur in some pressure vessels and piping systems used in industrial processes. The hot spots could be a result of, for instance, localized loss of refractory lining on the inside of pressure components or due to a maldistribution of process flow within vessels containing catalysts. The consequences of these hot spots on the structural integrity of pressure components are of considerable importance to plant operators. The paper addresses structural integrity issues in the context of codes and standards design framework. Interaction of hot spots, as is the case when multiple hot spots occur, is addressed. An assessment method, suitable for further development of a Level 2 “Fitness-for-Service” methodology, is discussed and applied to a commonly used pressure component configuration.
Finite Element Modeling of Fatigue Damage Using a Continuum Damage Mechanics Approach
Authors: De Jesus Abı´lio M. P. , Ribeiro Alfredo S. , Fernandes Anto´nio A.
Published: June 2005

In this paper, a fatigue model formulated in the framework of the continuum damage mechanics (CDM) is presented. The model is based on an explicit definition of fatigue damage and introduces a kinematic damage differential equation formulated directly as a function of the number of cycles and the stress cycle parameters. The model is initially presented for uniaxial problems, which facilitates the identification of its constants. An extension of the fatigue model to multiaxial problems is also proposed. This model was implemented in a nonlinear finite element code in conjunction with a constitutive model for cyclic plasticity. The cyclic plasticity model considered is based on a J2-plasticity theory with nonlinear isotropic and kinematic hardenings. In order to enhance the description of the cyclic elastoplastic behavior, the superposition of several nonlinear kinematic hardening variables is suggested. Both fatigue and plasticity models are identified for the P355NL1 (TStE355) steel. Finally, the numerical model is used to predict the fatigue crack initiation for a welded nozzle-to-plate connection, made of P355NL1 steel, and results are compared with experimental fatigue data.
Combined Influence of Mass and Thermal Stratification on
Double-Diffusion Non-Darcian Natural Convection From a Wavy Vertical Wall to
Porous Media
Authors: Rathish Kumar B. V. , Shalini
Published: June 2005

In this study we analyze the combined influence of mass and thermal stratification on non-Darcian double-diffusive natural convection from a wavy vertical wall to a porous media. A finite difference scheme based on the Keller box approach is derived for the boundary layer equations resulting from the use of nonsimilarity transformation on the coupled nonlinear partial differential equations. Extensive numerical simulations are carried out to analyze the influence of wave amplitude a, Grashof number Gr*, thermal stratification parameter ST, concentration stratification parameter SC, buoyancy ratio B, and Lewis number Le on the double-diffusive natural convection process. Increasing a and Gr* or decreasing B is seen to favor the heat and mass transport in the porous region thereby reducing the heat and mass fluxes along the vertical heated surface. Increasing ST or decreasing Le leads to an enhanced mass transfer process. Presence of surface waviness brings in a wavy pattern in the local heat and mass fluxes with decreasing magnitudes in the streamwise direction in the presence of stratification terms.
Particle Image Velocimetry Based Measurement of Entropy Production With Free Convection Heat Transfer
Authors: Adeyinka O. B. , Naterer G. F.
Published: June 2005

Local entropy production rates are determined from a numerical and experimental study of natural convection in an enclosure. Numerical predictions are obtained from a control-volume-based finite element formulation of the conservation equations and the Second Law. The experimental procedure combines methods of particle image velocimetry and planar laser induced fluorescence for measured velocity and temperature fields in the enclosure. An entropy based conversion algorithm in the measurement procedure is developed and compared with numerical predictions of free convection in the cavity. The predicted and measured results show close agreement. A measurement uncertainty analysis suggests that the algorithm postprocesses velocities (accurate within ±0.5%) to give entropy production data, which is accurate within ±8.77% near the wall. Results are reported for free convection of air and water in a square cavity at various Rayleigh numbers. The results provide measured data for tracking spatial variations of friction irreversibility and local exergy losses.
Thermal Contact Conductance Across Gold-Coated OFHC Copper Contacts in Different Media
Authors: Kshirsagar, Bapurao , Misra, Prashant , Jampana, and Nagaraju , Murthy M. V. Krishna
Published: June 2005

The thermal contact conductance studies across gold-coated oxygen-free high-conductivity copper contacts have been conducted at different contact pressures in vacuum, nitrogen, and helium environments. It is observed that the thermal contact conductance increases not only with the increase in contact pressure but also with the increase in thermal conductivity of interstitial medium. The experimental data are found to be in good agreement with the literature.
On Electrokinetic Mass Transport in a Microchannel With Joule Heating Effects
Authors: Tang and G. Y. , Yang C. , Gong, H. Q. , Chai, and C. J. , Lam Y. C.
Published: June 2005

This study presents a numerical analysis of electrokinetic mass transport in a microchannel with Joule heating effects. A nonuniform electric field caused by the presence of the Joule heating is considered in the model development. Numerical computations for electrokinetic mass transport under Joule heating effects are carried out using the Crank-Nicolson scheme of second-order accuracy in space and time for two different cases: (i) the translating interface and (ii) the dispersion of a finite sample plug. The simulations reveal that the presence of Joule heating not only causes the sample species to transport faster, but also causes the sample peak to decrease and the sample band to deviate from its flat interface or pluglike shape.
Planar Parameterization for Closed Manifold Genus-g Meshes Using Any Type of Positive Weights
Authors: Steiner D. , Fischer A.
Published: June 2005

Parameterization of 3D meshes is important for many graphic and CAD applications, in particular for texture mapping, remeshing, and morphing. Current parameterization methods for closed manifold genus-g meshes usually involve cutting the mesh according to the object generators, adjusting the resulting boundary and then determining the 2D parameterization coordinates of the mesh vertices, such that the flattened triangles are not too distorted and do not overlap. Unfortunately, adjusting the boundary distorts the resulting parameterization, especially near the boundary. To overcome this problem for genus-g meshes we first address the special case of closed manifold genus-1 meshes by presenting cyclic boundary constraints. Then, we expand the idea of cyclic boundary constraints by presenting a new generalized method developed for planar parameterization of closed manifold genus-g meshes. A planar parameterization is constructed by exploiting the topological structure of the mesh. This planar parameterization can be represented by a surface which is defined over parallel g-planes that represents g-holes. The proposed parameterization method satisfies the nonoverlapping requirement for any type of positive barycentric weights, including asymmetric weights. Moreover, convergence is guaranteed according to the Gauss-Seidel method.
Automatic Building of Structured Geological Models
Authors: Brandel Sylvain , Schneider Sébastien , Perrin Michel , Guiard Nicolas , Rainaud Jean-Français , Lienhard Pascal , Bertrand Yves
Published: June 2005

The present article proposes a method to significantly improve the construction and updating of 3D geological models used for oil and gas exploration. We present a prototype of a “geological pilot” which enables monitoring the automatic building of a 3D model topologically and geologically consistent, on which geological links between objects can easily be visualized. This model can automatically be revised in case of changes in the geometric data or in the interpretation.
Shape Tuning in Fully Free-Form Deformation Features
Authors: Pernot J-P. , Guillet S. , Léon J-C. , Falcidieno B. , Giannini F.
Published: June 2005

In this paper, an approach for shape tuning and predictable surface deformation is proposed. It pertains to the development of Fully Free Form Deformation Features (δ‐F4) which have been proposed to avoid low-level manipulations of free form surfaces. In our approach, δ‐F4 are applied through the specification of higher level parameters and constraints such as curves and points to be interpolated by the resulting surfaces. From the system perspective, the deformation is performed through the modification of the static equilibrium of bar networks coupled to the control polyhedra of the trimmed patches composing the free form surfaces on which the δ‐F4 are defined. The equations system coming from the constraints specification is often underconstrained, the selection of one among the whole set of possible solutions requires the definition of an optimization problem where an objective function has to be minimized. In this paper we propose a formulation of this optimization problem where the objective function can be defined as a multiple combination of various local quantities related either to the geometry of the bar network (e.g., the length of a bar or the displacement of a node), or to its mechanical characteristics (e.g. the external force applied at a node or a bar deformation energy). Different types of combinations are also proposed and analyzed according to the induced shape behaviors. In this way the shape of a δ‐F4 can be controlled globally, with a unique minimization, or locally with different minimizations applied to subdomains of the surface.
Labeling Engineering Line Drawings Using Depth Reasoning
Authors: Martin R. R. , Suzuki H. , Varley P. A. C.
Published: June 2005

Automatic creation of B-rep models of engineering objects from freehand sketches would benefit designers. One step aims to take a line drawing (with hidden lines removed), and from it deduce an initial three-dimensional (3D) geometric realization of the visible part of the object, including junction and line labels, and depth coordinates. Most methods for producing this frontal geometry use line labeling, which takes little or no account of geometry. Thus, the line labels produced can be unreliable. Our alternative approach inflates a drawing to produce provisional depth coordinates, and from these makes deductions about line labels. Assuming many edges in the drawing are parallel to one of three main orthogonal directions, we first attempt to identify groups of parallel lines aligned with the three major axes of the object. From these, we create and solve a linear system of equations relating vertex coordinates, in the coordinate system of the major axes. We then inflate the drawing in a coordinate system based on the plane of the drawing and depth perpendicular to it. Finally, we use this geometry to identify which lines in the drawing correspond to convex, concave, or occluding edges. We discuss alternative realizations of some of the concepts, how to cope with nonisometric-projection drawings, and how to combine this approach with other labeling techniques to gain the benefits of each. We test our approach using sample drawings chosen to be representative of engineering objects. These highlight difficulties often overlooked in previous papers on line labeling. Our new approach has significant benefits.
Detail-Preserving Variational Surface Design With Multiresolution
Constraints
Authors: Boier-Martin Ioana , Ronfard Remi , Bernardini Fausto
Published: June 2005

We present a variational framework for rapid shape prototyping. The modeled shape is represented as a Catmull-Clark multiresolution subdivision surface which is interactively deformed by direct user input. Free-form design goals are formulated as constraints on the shape and the modeling problem is cast into a constrained optimization one. The focus of this paper is on handling multiresolution constraints of different kinds and on preserving surface details throughout the deformation process. Our approach eliminates the need for an explicit decomposition of the input model into frequency bands and the overhead associated with saving and restoring high-frequency detail after global shape fairing. Instead, we define a deformation vector field over the model and we optimize its energy. Surface details are considered as part of the rest shape and are preserved during free-form model editing. We explore approximating the solution of the optimization problem to various degrees to balance trade-offs between interactivity and accuracy of the results.
Supersonic Flow Separation with Application to Rocket Engine Nozzles
Authors: O¨stlund J. , Muhammad-Klingmann B.
Published: June 2005

The past decade has seen a qualitative advancement of our understanding of physical phenomena involved in flow separation in supersonic nozzles; in particular, the problem of side loads due to asymmetrical pressure loads, which constitutes a major restraint in the design of nozzles for satellite launchers. The development in this field is to a large extent motivated by the demand for high-performance nozzles in rocket engineering. The present paper begins with an introduction to the physical background of shock-boundary-layer interactions in basic 2D configurations, and then proceeds to internal axisymmetric nozzle flow. Special attention is given to past and recent efforts in modeling and prediction, turning physical insight into applied engineering tools. Finally, an overview is given on different technical solutions to the problem if separation and side loads, discussed in the context of rocket technology.
Development of an Analytical Tool for the Design of Deep Water Riser/Flow Line Thermal Insulation Systems
Authors: Williams Dara , Harte Annette , Grealish Frank
Published: June 2005

The offshore oil and gas industry is predicting the discovery of more and more deep water reservoirs. Increased water depths create a requirement for reliable pipelines to economically recover these deep water fields and also to minimize flow assurance problems. Increased flow assurance problems in deeper waters increase the need for thermally insulated pipelines. In this paper we present an overview of the key issues in the analysis and design of thermal insulation systems, identify and discuss how these are addressed by the design tools developed within the DeFRIS project and present results used to validate the algorithms incorporated into the design tool.
Assessment of Corrosion Risks to Aging Ships Using an Experience Database
Authors: Wang Ge , Spencer John , Sun Haihong
Published: June 2005

Damages to ships due to corrosion are very likely, and the likelihood increases with the aging of ships. Risk and reliability approaches are more and more frequently applied in design and maintenance planning. These advanced approaches require reliable data reflecting the structural condition of ships in service. Such data is scarce. This paper presents a database of corrosion wastage. It is based on over 110,000 thickness measurements recently collected from 140 trading tankers. This database is larger than most other corrosion databases in the public domain. Corrosion wastage exhibits a high level of variability. In addition to thickness measurements of individual structural members, this database also has information on hull girder’s geometrical properties and strength of ships in service. Corrosion wastage has an influence on the hull girder strength. Statistical interpretations of the database are used to represent corrosion wastage in oil tankers. The severity of corrosion is ranked by three levels: slight, moderate, and severe levels corresponding respectively to 50%, 75%, and 95% cumulative probability on the database. The risks of corrosion wastage to aging ships’ structural integrity are assessed using the observations of the corrosion wastage database. The investigated risks are loss of local member’s strength, loss of global hull girder strength, and shortened inspection intervals. The experience database can be used in many aspects, such as design requirements for corrosion additions and wastage allowance for plate renewal, establishment of limits to hull girder strength of FPSOs, time variant reliability approach, and risk based inspection schemes.
Speed-Power Performance of 95,000DWT Arctic Tanker Design
Authors: Kim H. S. , Ha M. K. , Williams F. M. , Molyneux D. , Chun H. H.
Published: June 2005

When Arctic offshore development in the 1970s first led to consideration of ice capable tankers, there was a high level of uncertainty over design requirements for both safety and ship performance, and a lack of reliable methods to evaluate design proposals. Since that time, improved understanding of the ice environment has raised the confidence of design specifications. Parallel developments have resulted in a suite of engineering tools for ship performance evaluation at the design stage. Recent development of offshore and near shore oil and gas reserves in several countries, together with economic studies of increased transportation through the Russian Arctic, led to renewed interest in ice capable tanker design. In response, Samsung Heavy Industries (SHI) applied its experience in tanker design and construction to the design of a specialized tanker with ice capability. SHI produced two prototype hull designs for further study. The performance of both hulls and of the propellers was evaluated at the Institute for Ocean Technology (IOT) in St. John’s, Newfoundland. This paper discusses the development of the design, describes the model experiments to determine performance and variations, and presents the results. It shows how physical modeling can provide insight into design features, and points out the areas where further research will have the greatest effect.
Fracture Mechanics Analysis of Fatigue Crack Repaired Joints
Authors: Rodríguez-Sánchez J. Efraín , Dover William D. , Brennan Feargal P. , Castellanos Alejandro Rodríguez
Published: June 2005

Fatigue life predictions based on fracture mechanics calculations are required to satisfy an increasing level of safety demanded by industry. These predictions are mainly used to schedule NDT inspections and with inspection data make structural integrity assessments. The periodic inspection-assessment process can lead to the implementation of a fatigue crack repair by crack removal. Fracture mechanics analysis is used again to determine whether or not a repair will be effective. For the case of tubular joints, in offshore structures, once repairs have been shown to be ineffective it is usually required to install a clamp to maintain the continuity of joint members if the structure is still required for production. In this paper a fracture mechanics analysis of crack repaired joints based on Y factors is presented. The analysis is used to predict fatigue life after crack removal and is validated against T-butts experimental data. The analysis is also extrapolated for the prediction of fatigue life of crack repaired tubular joints.
A General Formulation for the Strength Design of Axially Loaded Planar and Multiplanar Tubular Joints
Authors: Lee Marcus M. K. , Dexter Ellen M.
Published: June 2005

A database of newly generated numerical strengths of planar and multiplanar joints was used to assess the current offshore design code methodologies and to derive a new design equation, based on the AWS ovalization parameter concept. Within defined geometric limits, the proposed equation has been found to be generally applicable to any axially loaded joint configuration, provided that the braces do not overlap. It negates the need for potentially subjective brace classification to be carried out and accounts fully for planar and multiplanar effects. The proposed equation is fully validated against the planar and multiplanar data in the screened database complied by MSL Engineering, and has been shown to have similar accuracy as the existing design equations advocated by ISO, yet have significantly wider validity.
Dynamic Behavior and Optimization of Offshore Gravity Platforms
Authors: Mastanzade Nicat S. , Yazici Gökhan
Published: June 2005

This paper presents the results of a dynamic investigation with the aim of determining both the optimal shape of an offshore gravity platform column and the required mass of the infill water. The natural frequency formulation of the structure with the added infill water mass, Er, was obtained by using Rayleigh’s method. Pontyagin’s maximum variational principle was used to define the shape of the column. An algorithm and a computer program were developed to obtain the numerical solution of the problem. Finally, a scaled model of the gravity platform was built and tested, in order to verify the results obtained from the analytical research and to determine the mass of the infill water.
Risk Based Acceptance Criteria for Joints Subject to Fatigue Deterioration
Authors: Straub Daniel , Havbro Faber Michael
Published: June 2005

Different approaches to determine the acceptance criteria for fatigue induced failure of structural systems and components are discussed and compared. The considered approaches take basis in either optimization (societal cost-benefit analysis) or are derived from past and actual practice or codes (revealed preferences). The system acceptance criteria are expressed in terms of the maximal acceptable annual probability of collapse due to fatigue failure. Acceptance criteria for the individual fatigue failure modes are then derived using a simplified system reliability model. The consequence of fatigue failure of the individual joints is related to the overall system by evaluating the change in system reliability given fatigue failure. This is facilitated by the use of a simple indicator, the Residual Influence Factor. The acceptance criteria is thus formulated as a function of the system redundancy and complexity. In addition, the effect of dependencies in the structure on the acceptance criteria are investigated. Finally an example is presented where the optimal allocation of the risk to different welded joints in a jacket structure is performed by consideration of the necessary maintenance efforts.
Selection of Variables for Structural Redesign by Large Admissible Perturbations
Authors: Koo Bonhyung , Bernitsas Michael M.
Published: June 2005

Redesign or inverse design is the process of generating a new optimal design which satisfies performance specifications starting from a baseline design with undesirable performance. The LargE Admissible Perturbation (LEAP) methodology makes it possible to redesign a structure for large changes in performance objectives and redesign variables without trial and error or repetitive finite element analyses. The next level of challenge in redesign automation is to identify a priori the structural elements and their properties that have the biggest impact and use only those in redesign. Based on LEAP, guidelines are developed in this paper for identifying effective selection of redesign variables for improved accuracy and reduced CPU time. These guidelines enable the designer to define the elements to be redesigned, to partition those elements among redesign groups, and to specify redesign variables in each group. In the numerical applications, an offshore tower is used to verify the developed guidelines. Three models of this tower with 160, 320, and 480 elements are used.
Static Stress Redesign of Structures by Large Admissible Perturbations
Authors: Bernitsas Michael M. , Kristanto Bhineka M.
Published: June 2005

The LargeE Admissible Perturbation (LEAP) methodology is developed further to solve static stress redesign problems. The static stress general perturbation equation, which expresses the unknown nodal stresses of the objective structure in terms of the baseline structure stresses, is derived first. This equation depends on the redesign variables for each element or group of elements; namely, the cross-sectional area and moment of inertia, and the distance between the neutral axis and the outer fiber of the cross section. This equation preserves the shape of the cross section in the redesign process. LEAP enables the designer to redesign a structure to achieve specifications on modal properties, static displacements, forced response amplitudes, and static stresses. LEAP is implemented in code RESTRUCT which post-processes the FEA results of the baseline structure. Changes on the order of 100% in the above performance particulars and in redesign variables can be achieved without repetitive finite element (FE) analyses. Several numerical applications on a simple cantilever beam and an offshore tower are used to verify the LEAP algorithm for stress redesign.
Linearization in Analysis of Nonlinear Stochastic Systems: Recent Results—Part I: Theory
Authors: Socha L.
Published: June 2005

The purpose of Part 1 of this paper is to provide a review of recent results from 1991 through 2003 in the area of theoretical aspects of statistical and equivalent linearization in the analysis of structural and mechanical nonlinear stochastic dynamic systems. First, a discussion about misunderstandings appearing in the literature in derivation of linearization coefficients for mean-square linearization criterion is presented. In Secs. 3–6 new theoretical results, including new types of criteria, nonlinearities, and excitations in the context of linearization methods, are reviewed. In particular, moment criteria called energy criteria, linearization criteria in the space of power spectral density functions and probability density functions are discussed. A survey of a wide class of so-called nonlinearization techniques, including equivalent quadratization and equivalent cubicization methods, is given in Sec. 7. New linearization techniques for nonlinear stochastic systems with parametric Gaussian excitations and external non-Gaussian excitations are discussed in Secs. 8 and 9, respectively. In the last sections, four surveys of papers where stochastic linearization is used as a mathematical tool in other theoretical approaches, namely, models of dynamic systems with hysteresis, finite element method, and control of nonlinear stochastic systems and linearization with sensitivity analysis, are given. A discussion of the accuracy analysis of linearization techniques and some general conclusions close this paper. There are 217 references cited in this revised article.