bluuebunny/crossref_metadata_2025 huggingface dataset:
Domain growth kinetics in lithium niobate single crystals studied by piezoresponse force microscopy
Authors: Rodriguez B. J. , Nemanich R. J. , Kingon A. , Gruverman A. , Kalinin S. V. , Terabe K. , Liu X. Y. , Kitamura K.
Published: January 2005

The kinetics of sidewise domain growth in an inhomogeneous electric field has been investigated in stoichiometric LiNbO3 single crystals by measuring the lateral domain size as a function of the voltage pulse magnitude and duration using piezoresponse force microscopy. The domain size increases linearly with the voltage magnitude suggesting that the domain size is kinetically limited in a wide range of pulse magnitudes and durations. In spite of that, the written domains exhibit strong retention behavior. It is suggested that the switching behavior can be described by the universal scaling curve. Domain kinetics can be described as an activation process by calculating the field distribution using the charged sphere model under the assumption of an exponential field dependence of the wall velocity. The activation energy is found to be a function of the external field.
Mechanism for pinhole formation in GaN∕AlN∕Si(111) layers from steps at the substrate surface
Authors: Sanchez A. M. , Dimitrakopulos G. P. , Ruterana P.
Published: January 2005

High-resolution transmission electron microscopy has been used to investigate the connection between pinholes observed in the AlN buffer layer and steps at the (111) Si surface. Below the pinhole, two steps with different heights have been observed in the (111) Si substrate, which have been characterized using the topological theory formalism. The AlN growth on the top of such steps gives rise to islands with a nonzero displacement along the growth axis and the formation of c-component dislocations. The coalescence of these islands leads to the formation of highly strained areas, from which may originate pinholes.
Doubly resonant photonic crystal for efficient laser operation: Pumping and lasing at low group velocity photonic modes
Authors: Raineri F. , Vecchi G. , Yacomotti A. M. , Seassal C. , Viktorovitch P. , Raj R. , Levenson A.
Published: January 2005

An InP-based two-dimensional photonic crystal slab laser is optimized in order to exhibit low group velocity modes both at the pumping and the lasing wavelength. Laser operation is demonstrated at 1566nm in the pulsed regime. A threshold of 4kW∕cm2 is demonstrated by pumping at the photonic mode lying in the bound quantum well electronic levels, one longitudinal optical phonon energy below the lasing photonic mode.
Ultraviolet emission from argon water-vapor mixtures excited with low-energy electron beams
Authors: Morozov A. , Krücken R. , Ottenthal T. , Ulrich A. , Wieser J.
Published: January 2005

A 310-nm-ultraviolet light source operating at the OH (AΣ+2→XΠ2) transition is presented. The OH band is emitted from argon water-vapor mixtures excited with low-energy (15 keV) electron beams. The light output is studied in the argon pressure range from 250 to 1000 hPa. In this study, the highest OH band intensity was observed at the lowest Ar pressure and a water-vapor concentration of about 0.02%. An efficiency of 3% for converting electron beam power into light emission was measured under these conditions.
Measurements of 1∕f noise in Josephson junctions at zero voltage: Implications for decoherence in superconducting quantum bits
Authors: Mück Michael , Korn Matthias , Mugford C. G. A. , Kycia J. B. , Clarke John
Published: January 2005

Critical current fluctuations with a 1∕f spectral density (f is frequency) are potentially a limiting source of intrinsic decoherence in superconducting quantum bits (qubits) based on Josephson tunnel junctions. Prior measurements of this noise were made at nonzero voltages whereas qubits are operated in the zero voltage state. We report measurements of 1∕f noise in a dc superconducting quantum interference device first, coupled to a resonant tank circuit and operated in a dispersive mode at zero voltage, and, second, operated conventionally with a current bias in the voltage regime. Both measurements yield essentially the same magnitude of critical current 1∕f noise.
Formation of SiC-surface nanocrystals by ion implantation and electron beam rapid thermal annealing
Authors: Markwitz A. , Johnson S. , Rudolphi M. , Baumann H. , Mücklich A.
Published: January 2005

SiC-surface nanostructures on silicon were produced by 10keV carbon ion implantation into silicon followed by annealing to 1000°C for 15s under high-vacuum conditions using a raster-scanned electron beam. Following implantation, an amorphous layer is produced which starts at the surface and extends 65nm into the substrate. Following annealing, the implanted surface layer remains amorphous but becomes covered with semi-spherical crystalline features up to 300nm in diameter. The nanocrystals have been confirmed to be SiC which, following nucleation, grow as a result of C and Si diffusion across the oxide free substrate surface during annealing.
Possibility of transmutation of Cs135 by ultraintense laser
Authors: Takashima R. , Hasegawa S. , Nemoto K. , Kato K.
Published: January 2005

The possibility of photo-transmutation of long-lived nuclide Cs135 by ultrashort ultraintense laser was analytically evaluated. The yield of Cs135(γ,n) Cs134 was strongly dependent on the laser intensity at around 1020W∕cm2. If Cs135 were irradiated by such a laser with the intensity of 1021W∕cm2 and 10 Hz for 30 min, characteristic γ-ray counting rate was estimated to be 3 Bq.
Ultraviolet amplified spontaneous emission from self-organized network of zinc oxide nanofibers
Authors: Xu C. X. , Sun X. W. , Yuen Clement , Chen B. J. , Yu S. F. , Dong Z. L.
Published: January 2005

Self-organized zinc oxide (ZnO) nanofiber network with six-fold symmetry was fabricated on ZnO-buffered (0001) sapphire substrate with patterned gold catalyst by vapor-phase transport method. From the ZnO buffer layer, hexagonal ZnO nanorods with identical in-plane structure grew epitaxially along [0001] orientation to form vertical stems. The nanofiber branches grew horizontally from six side-surfaces of the vertical stem along [011¯0] and other equivalent directions. The aligned network structure constructed a waveguide array with optical gain. Ultraviolet amplified spontaneous emission was observed along the side-branching nanofibers when the aligned ZnO network was excited by a frequency-tripled Nd:YAG laser.
Advanced High-Turning Compressor Airfoils for Low Reynolds Number Condition—Part II: Experimental and Numerical Analysis
Authors: Schreiber Heinz-Adolf , Steinert Wolfgang , Sonoda Toyotaka , Arima Toshiyuki
Published: January 2005

Part I of this paper describes the design and optimization of two high turning subsonic compressor cascades operating as an outlet guide vane (OGV) behind a single stage low pressure turbine at low Reynolds number condition Re=1.3×105. In the numerical optimization algorithm, the design point and off-design performance has been considered in an objective function to achieve a wide low loss incidence range. The objective of the present paper is to examine some of the characteristics describing the new airfoils as well as to prove the reliability of the design process and the applied flow solver. Some aerodynamic characteristics for the two new airfoils and a conventional controlled diffusion airfoil (CDA), have been extensively investigated in the cascade wind tunnel of DLR Cologne. For an inlet Mach number of 0.6 the effect of Reynolds number and incidence angle on each airfoil performance is discussed, based on experimental and numerical results. For an interpretation of the airfoil boundary layer behavior, results of some boundary layer calculations are compared to oil flow visualization pictures. The design goal of an increased low loss incidence range at low Reynolds number condition could be confirmed without having a negative effect on the high Reynolds number region.
Method for Direct Parametric Analysis of Nonlinear Forced Response of Bladed Disks With Friction Contact Interfaces
Authors: Petrov E. P.
Published: January 2005

An effective method for direct parametric analysis of periodic nonlinear forced response of bladed disks with friction contact interfaces has been developed. The method allows, forced response levels to be calculated directly as a function of contact interface parameters such as the friction coefficient, contact surface stiffness (normal and tangential coefficients), clearances, interferences, and the normal stresses at the contact interfaces. The method is based on exact expressions for sensitivities of the multiharmonic interaction forces with respect to variation of all parameters of the friction contact interfaces. These novel expressions are derived in the paper for a friction contact model, accounting for the normal load variation and the possibility of separation-contact transitions. Numerical analysis of effects of the contact parameters on forced response levels has been performed using large-scale finite element models of a practical bladed turbine disk with underplatform dampers and with shroud contacts.
Thermoacoustic Stability of Quasi-One-Dimensional Flows–Part I: Analytical and Numerical Formulation
Authors: Prasad Dilip , Feng Jinzhang
Published: January 2005

A numerical method is developed for transient linear analysis of quasi-one-dimensional thermoacoustic systems, with emphasis on stability properties. This approach incorporates the effects of mean flow variation as well as self-excited sources such as the unsteady heat release across a flame. Working in the frequency domain, the perturbation field is represented as a superposition of local wave modes, which enables the linearized equations to be integrated in space. The problem formulation is completed by specifying appropriate boundary conditions. Here, we consider impedance boundary conditions as well as those relevant to choked and shocked flows. For choked flows, the boundary condition follows from the requirement that perturbations remain regular at the sonic point, while the boundary conditions applicable at a normal shock are obtained from the shock jump conditions. The numerical implementation of the proposed formulation is described for the system eigenvalue problem, where the natural modes are sought. The scheme is validated by comparison with analytical and numerical solutions.
Rotor-Stator Interactions in a Four-Stage Low-Speed Axial Compressor—Part I: Unsteady Profile Pressures and the Effect of Clocking
Authors: Mailach Ronald , Vogeler Konrad
Published: January 2005

This two-part paper presents detailed experimental investigations of unsteady aerodynamic blade row interactions in the four-stage Low-Speed Research Compressor of Dresden. In part I of the paper the unsteady profile pressure distributions for the nominal setup of the compressor are discussed. Furthermore, the effect of blade row clocking on the unsteady profile pressures is investigated. Part II deals with the unsteady aerodynamic blade forces, which are calculated from the measured profile pressure distributions. The unsteady pressure distributions were analyzed in the first, a middle and the last compressor stage both on the rotor and stator blades. The measurements were carried out on pressure side and suction side at midspan. Several operating points were investigated. A complex behavior of the unsteady profile pressures can be observed, resulting from the superimposed influences of the wakes and the potential effects of several up- and downstream blade rows of the four-stage compressor. The profile pressure changes nearly simultaneously along the blade chord if a disturbance arrives at the leading edge or the trailing edge of the blade. Thus the unsteady profile pressure distribution is nearly independent of the convective wake propagation within the blade passage. A phase shift of the reaction of the blade to the disturbance on the pressure and suction side is observed. In addition, clocking investigations were carried out to distinguish between the different periodic influences from the surrounding blade rows. For this reason the unsteady profile pressure distribution on rotor 3 was measured, while stators 1–4 were separately traversed stepwise in the circumferential direction. Thus the wake and potential effects of the up- and downstream blade rows on the unsteady profile pressure could clearly be distinguished and quantified.
Parametric Study of Tip Clearance—Casing Treatment on Performance and Stability of a Transonic Axial Compressor
Authors: Beheshti Behnam H. , Teixeira Joao A. , Ivey Paul C. , Ghorbanian Kaveh , Farhanieh Bijan
Published: January 2005

The control of tip leakage flow through the clearance gap between the moving and stationary components of rotating machines is still a high-leverage area for improvement of stability and performance of aircraft engines. Losses in the form of flow separation, stall, and reduced rotor work efficiency are results of the tip leakage vortex (TLV) generated by interaction of the main flow and the tip leakage jet induced by the blade pressure difference. The effects are more detrimental in transonic compressors due to the interaction of shock TLV. It has been previously shown that the use of slots and grooves in the casing over tip of the compressor blades, known as casing treatment, can substantially increase the stable flow range and therefore the safety of the system but generally with some efficiency penalties. This paper presents a numerical parametric study of tip clearance coupled with casing treatment for a transonic axial-flow compressor NASA Rotor 37. Compressor characteristics have been compared to the experimental results for smooth casing with a 0.356 mm tip clearance and show fairly good agreement. Casing treatments were found to be an effective means of reducing the negative effects of tip gap flow and vortex, resulting in improved performance and stability. The present work provides guidelines for improvement of steady-state performance of the transonic axial-flow compressors and improvement of the stable operating range of the system.
Detailed Flow Study of Mach Number 1.6 High Transonic Flow With a Shock Wave in a Pressure Ratio 11 Centrifugal Compressor Impeller
Authors: Higashimori Hirotaka , Hasagawa Kiyoshi , Sumida Kunio , Suita Tooru
Published: January 2005

Requirements for aeronautical gas turbine engines for helicopters include small size, low weight, high output, and low fuel consumption. In order to achieve these requirements, development work has been carried out on high efficiency and high pressure ratio compressors. As a result, we have developed a single stage centrifugal compressor with a pressure ratio of 11 for a 1000 shp class gas turbine. The centrifugal compressor is a high transonic compressor with an inlet Mach number of about 1.6. In high inlet Mach number compressors, the flow distortion due to the shock wave and the shock boundary layer interaction must have a large effect on the flow in the inducer. In order to ensure the reliability of aerodynamic design technology, the actual supersonic flow phenomena with a shock wave must be ascertained using measurement and Computational Fluid Dynamics (CFD). This report presents the measured results of the high transonic flow at the impeller inlet using Laser Doppler Velocimeter (LDV) and verification of CFD, with respect to the high transonic flow velocity distribution, pressure distribution, and shock boundary layer interaction at the inducer. The impeller inlet tangential velocity is about 460 m/s and the relative Mach number reaches about 1.6. Using a LDV, about 500 m/s relative velocity was measured preceding a steep deceleration of velocity. The following steep deceleration of velocity at the middle of blade pitch clarified the cause as being the pressure rise of a shock wave, through comparison with CFD as well as comparison with the pressure distribution measured using a high frequency pressure transducer. Furthermore, a reverse flow is measured in the vicinity of casing surface. It was clarified by comparison with CFD that the reverse flow is caused by the shock-boundary layer interaction. Generally CFD shows good agreement with the measured velocity distribution at the inducer and splitter inlet, except in the vicinity of the casing surface.
Experimental Study of the Effect of Periodic Unsteady Wake Flow on Boundary Layer Development, Separation, and Reattachment Along the Surface of a Low Pressure Turbine Blade
Authors: Schobeiri M. T. , O¨ztu¨rk B.
Published: January 2005

The paper experimentally studies the effects of periodic unsteady wake flow on boundary layer development, separation and reattachment along the suction surface of a low pressure turbine blade. The experimental investigations were performed on a large scale, subsonic unsteady turbine cascade research facility at the Turbomachinery Performance and Flow Research Laboratory (TPFL), Texas A&M University. The experiments were carried out at a Reynolds number of 110,000 (based on suction surface length and exit velocity) with a free-stream turbulence intensity of 1.9%. One steady and two different unsteady inlet flow conditions with the corresponding passing frequencies, wake velocities, and turbulence intensities were investigated. The reduced frequencies cover the entire operating range of LP turbines. In addition to the unsteady boundary layer measurements, blade surface measurements were performed at the same Reynolds number. The surface pressure measurements were also carried out at one steady and two periodic unsteady inlet flow conditions. The results presented in ensemble-averaged, and the contour plot forms help to understand the physics of the separation phenomenon under periodic unsteady wake flow. It was found that the suction surface displayed a strong separation bubble for these three different reduced frequencies. For each condition, the locations and the heights defining the separation bubble were determined by carefully analyzing and examining the pressure and the mean velocity profile data. The location of boundary layer separation was independent of the reduced frequency level. However, the extent of the separation was strongly dependent on the reduced frequency level. Once the unsteady wake started to penetrate into the separation bubble, the turbulent spot produced in the wake paths caused a reduction of the separation bubble height.
Meshfree Methods
Authors: Belytschko Ted , Rabczuk Timon , Huerta Antonio , Fernández‐Méndez Sonia
Published: January 2005

The aim of this chapter is to provide an in‐depth presentation and survey of meshfree particle methods. Several particle approximations are reviewed; the smooth particle hydrodynamic (SPH) method, corrected gradient methods, and the moving least squares (MLS) approximation. The discrete equations are derived from a collocation scheme or a Galerkin method. Special attention is paid to the treatment of essential boundary conditions. A brief review of radial basis functions is given because they play a significant role in meshfree methods. Finally, different approaches for modelling discontinuities in meshfree methods are described.
Adaptive Wavelet Techniques in Numerical Simulation
Authors: Cohen Albert , Dahmen Wolfgang , DeVore Ronald
Published: January 2005

This chapter highlights recent developments concerning adaptive wavelet methods for time dependent and stationary problems. The first problem class focuses on hyperbolic conservation laws in which wavelet concepts exploit sparse representations of the conserved variables. Regarding the second problem class, we begin with matrix compression in the context of boundary integral equations in which the key issue is now to obtain sparse representations of (global) operators like singular integral operators in wavelet coordinates. In the remainder of the chapter, a new fully adaptive algorithmic paradigm along with some analysis concepts are outlined, which, in particular, work for nonlinear problems and where the sparsity of both, functions and operators, is exploited.
Plates and Shells: Asymptotic Expansions and Hierarchic Models
Authors: Dauge Monique , Faou Erwan , Yosibash Zohar
Published: January 2005

Concerning thin structures, such as plates and shells, the idea of reducing the equations of elasticity to two‐dimensional models defined on the midsurface seems relevant. Such a reduction was first performed thanks to kinematical hypotheses about the transformation of normal lines to the midsurface. As nowadays, the asymptotic expansion of the displacement solution of the three‐dimensional linear model is fully known at least for plates and clamped elliptic shells, we start from a description of these expansions in order to introduce the two‐dimensional models known as hierarchical models: These models extend the classical models, and presuppose the displacement to be polynomial in the thickness variable, transverse to the midsurface. Because of the singularly perturbed character of the elasticity problem as the thickness approaches zero, boundary, or internal layers may appear in the displacements and stresses, and so may numerical locking effects. The use of hierarchical models, discretized by higher degree polynomials (p‐version of finite elements) may help overcome these severe difficulties.
Multigrid Methods forFEMandBEMApplications
Authors: Hackbusch Wolfgang
Published: January 2005

After discretization of the partial differential equations from mechanics, one usually obtains large systems of (non)linear equations. Their efficient solution requires the use of fast iterative methods. Multigrid iterations are able to solve linear and nonlinear systems with a rather fast rate of convergence, provided the problem is of elliptic type. The contribution describes the basic construction of multigrid methods, their ingredients, related methods, and their application to various problem classes.

Although most of the applications concern FEM discretizations of partial differential equations, there are also applications to integral equations as they occur in boundary element methods (BEM).
Panel Clustering Techniques and Hierarchical Matrices forBEMandFEM
Authors: Hackbusch Wolfgang
Published: January 2005

The panel clustering method and the hierarchical matrix technique described here are important tools for the efficient treatment of fully populated matrices that arise from boundary element (BEM) problems and elliptic FEM problems.
Domain Decomposition Methods and Preconditioning
Authors: Korneev V. G. , Langer U.
Published: January 2005

Domain decomposition methods nowadays provide powerful tools for constructing efficient parallel solvers for large‐scale systems of algebraic equations arising from the discretization of partial differential equations. The classical alternating Schwarz method and the classical substructuring technique have led to advanced overlapping and nonoverlapping domain decomposition solvers (preconditioners), that can be analyzed from a unified point of view now calledSchwarz theory. This survey article starts with a brief historical overview, provides the basic results of the Schwarz theory, looks at some overlapping domain decomposition methods (preconditioners) in brief, and discusses more extensively various nonoverlapping domain decomposition techniques.
Models and Finite Elements for Thin‐Walled Structures
Authors: Bischoff M. , Bletzinger K.‐U. , Wall W. A. , Ramm E.
Published: January 2005

The present study provides an overview of modeling and discretization aspects in finite element analysis of thin‐walled structures. Shell formulations based upon derivation from three‐dimensional continuum mechanics, the direct approach, and the degenerated solid concept are compared, highlighting conditions for their equivalence.

Rather than individually describing the innumerable contributions to theories and finite element formulations for plates and shells, the essential decisions in modeling and discretization, along with their consequences, are discussed. It is hoped that this approach comprises a good amount of the existing literature by including most concepts in a generic format.

The contribution focuses on nonlinear finite element formulations for large displacements and rotations in the context of elastostatics. Although application to dynamics and problems involving material nonlinearities is straightforward, these subjects are not taken into account explicitly.
Crystal Plasticity and Evolution of Polycrystalline Microstructure
Authors: Miehe Christian , Schotte Jan
Published: January 2005

The continuum slip theory of crystals provides a canonical framework of finite plasticity with physically well‐defined roots in the dislocation mechanics of metals. Reliable algorithmic settings of crystal plasticity are not only needed for structural analyses of single crystals but also provide a cornerstone for multiscale computations of evolving anisotropic microstructures in metallic polycrystals. This article summarizes a current status of computational crystal plasticity and its application to the texture analysis of polycrystals. It outlines a basic constitutive structure of crystal plasticity, alternative deformation‐driven stress update algorithms and a computational scheme for the nonlinear homogenization of polycrystalline aggregates. Particular emphasis is put on a canonical incremental variational formulation for Schmid‐type crystal plasticity with potential hardening where an incremental stress potential is obtained from a local minimization problem with respect to the internal variables. The existence of this stress potential allows the formulation of IBVPs for elastic–plastic crystals as a sequence of incremental minimization problems. Furthermore, the nonlinear homogenization of polycrystalline microstructures may be recast into a principle of minimum averaged incremental energy. Within this variational setting of homogenization, a quasi‐hyperelastic incremental macro‐stress potential is obtained from a global minimization problem with respect to the fine‐scale displacement fluctuation field. The performance of the formulations is demonstrated for benchmarks of single crystal plasticity and texture developments in polycrystals.
Computational Concrete Mechanics
Authors: Lackner Roman , Mang Herbert A. , Pichler Christian
Published: January 2005

This chapter contains a report on recent developments in the field of computational concrete mechanics, introducing the multiscale concept for the simulation of cement‐based materials and, in the case of reinforced concrete (RC), of the steel–concrete interaction. In this concept, several scales of observation may be considered simultaneously in the numerical analysis. Alternatively, material properties, which serve as input for macroscopic analyses, are related to properties of material phases and their assemblage at finer scales of observation. The benefits of multiscale approaches in computational concrete mechanics are illustrated by two analyses of real‐life structures employing macroscopic material properties for plain and reinforced concrete related to finer scales of observation.
Acoustics
Authors: Thompson Lonny L. , Pinsky Peter M.
Published: January 2005

State‐of‐the‐art computational methods for linear acoustics are reviewed. The equations of linear acoustics are summarized and then transformed to the frequency domain for time‐harmonic waves governed by the Helmholtz equation. Two major current challenges in the field are specifically addressed: numerical dispersion errors that arise in the approximation of short unresolved waves, polluting resolved scales and requiring a large computational effort, and the effective treatment of unbounded domains by domain‐based methods. A discussion of the indefinite sesquilinear forms in the corresponding weak form are summarized. A priori error estimates, including both dispersion (phase error) and global pollution effects for moderate to large wave numbers in finite element methods, are discussed. Stabilized and other wave‐based discretization methods are reviewed. Domain‐based methods for modeling exterior domains are described including Dirichlet‐to‐Neumann (DtN) methods, absorbing boundary conditions, infinite elements, and the perfectly matched layer (PML). Efficient equation‐solving methods for the resulting complex‐symmetric (non‐Hermitian) matrix systems are discussed including parallel iterative methods and domain decomposition methods including the FETI‐H method. Numerical methods for direct solution of the acoustic wave equation in the time domain are reviewed.
Turbulence Closure Models for Computational Fluid Dynamics
Authors: Durbin Paul A.
Published: January 2005

The formulation of analytical turbulence closure models for use in computational fluid mechanics is described. The subject of this chapter is the types of models that are used to predict the statistically averaged flow field – commonly known as Reynolds‐averaged Navier–Stokes equations (RANS) modeling. A variety of models is reviewed: these include two‐equation, eddy viscosity transport, and second moment closures. How they are formulated is not a main theme; it enters the discussion but the models are presented largely at an operational level. Several issues related to numerical implementation are discussed. Relative merits of the various formulations are commented on.
CFD‐Based Nonlinear Computational Aeroelasticity
Authors: Farhat Charbel
Published: January 2005

This chapter overviews a three‐field formulation of nonlinear aeroelastic problems, where the fluid is modeled by the arbitrary Lagrangian–Eulerian (ALE) form of either the Euler or Navier–Stokes equations; the structure is represented by a detailed finite element model, and the fluid‐mesh is unstructured, dynamic, and constructed by a robust structure‐analogy–based method. It also discusses recent advances in the computational algorithms associated with this approach for modeling nonlinear fluid/structure interaction problems. These include CFD schemes that are formally second‐order time‐accurate on moving grids, energy‐transfer–conserving methods for discretizing transmission conditions across nonmatching fluid and structure discrete interfaces, and state‐of‐the‐art loosely coupled algorithms for solving efficiently coupled systems of fluid and structural equations arising from the discretization of real aircraft configurations. A taste of the capabilities of such algorithms is provided by reporting on their validation for an F‐16 fighter aircraft configuration in various subsonic, transonic, and supersonic airstreams, and at various load factors. The chapter concludes with a discussion of the feasibility and merit of the overviewed computational technology for accurately extracting the flutter envelopes of civilian and military aircraft, and a perspective on future research in CFD‐based nonlinear computational aeroelasticity.
The Use of Mixed Finite Element Methods for Viscoelastic Fluid Flow Analysis
Authors: Baaijens Frank P. T. , Hulsen Martien A. , Anderson Patrick D.
Published: January 2005

The numerical analysis of non‐Newtonian viscoelastic flows is a challenging task, and requires accurate, efficient, and robust computational methods. In this work, mixed finite element methods are used for that purpose. They are introduced within the context of closed‐form differential constitutive models. Their application to steady and time‐dependent viscoelastic flows and stability analysis is discussed. Application to model polymer melt flows is briefly addressed. These techniques can also be adapted to solve problems with models that cannot be written as closed‐form differential models. Two examples thereof are the deformation fields method for closed‐form constitutive equations and the Brownian configuration fields formulation for stochastic constitutive models.
Ship Hydrodynamics
Authors: Oñate Eugenio , García Julio , Idelsohn Sergio R. , Idelsohn Sergio R.
Published: January 2005

This chapter presents an overview of some computational methods for analysis of ship hydrodynamics problems. Attention is focused on the description of a stabilized finite element formulation derived via a finite calculus procedure. Both arbitrary Lagrangian–Eulerian (ALE) and fully Lagrangian forms are presented. Details of the treatment of the free‐surface waves and the interaction between the ship structure and the seawater are also given. Examples of application to a variety of ship hydrodynamics problems are shown.
Cluster kinetics of granular mixing
Authors: McCoy Benjamin J. , Madras Giridhar
Published: January 2005

Granular mixing of identical particles that cluster together is a challenging and important engineering problem. Mixing requires the breakup of clusters, both by individual particle detachment and cluster fragmentation. We apply a population balance (distribution kinetics) approach to describe such size‐distributed cluster processes. Expressions for mixing effectiveness and segregation measures are derived and expressed in terms of the rate coefficients for reversible cluster distribution kinetics. Analytical and numerical moment solutions illustrate how the novel method is implemented and also provide some realistic results. The method allows straightforward derivation of experimentally observed long‐time power law or exponential asymptotic behavior of segregation metrics for various rate coefficient expressions. © 2005 American Institute of Chemical Engineers AIChE J, 51: 406–414, 2005
Autistic‐like behavior in CHARGE syndrome
Authors: Hartshorne Timothy S. , Grialou Tina L. , Parker Kellie R.
Published: January 2005

Children with CHARGE syndrome frequently exhibit moderate to severe behavior difficulties, and are often diagnosed with obsessive‐compulsive disorder, attention deficit disorder, Tourette syndrome, and autism. Hartshorne and Cypher (2004) surveyed parents of 100 children with CHARGE worldwide and confirmed the prevalence of behaviors that are associated with these disorders. They also found behaviors that could be described as typical of persons who are deafblind. The present study examined whether the autistic‐like behaviors of children with CHARGE are more similar to those of children who are deafblind, to those of children who are autistic or are unique to CHARGE. Surveys including the Autism Behavior Checklist (ABC) were mailed to families of 204 children with CHARGE, and 160 usable surveys were returned (78%). Total scores on the ABC for children with CHARGE were significantly different from the norms for those with autism, and those who were deafblind. However, the variance for CHARGE was larger than for the normative groups, and 27.5% of those with CHARGE could be classified as autistic. The pattern of subscale scores for those with CHARGE differed from the other normative groups. © 2005 Wiley‐Liss, Inc.
The epitaxial growth of gallium arsenide using triethylarsine
Authors: Maeda T , Hata M , Zempo Y , Fukuhara N , Matsuda Y , Sawara K
Published: January 2005

The thermal decomposition of triethylarsine (TEAs) has been studied. It decomposes at a lower temperature than arsine (AsH3). The decomposition proceeds via a radical process at a temperature above 700°C. Epitaxial growth using TEAs has been investigated. A gallium arsenide (GaAs) layer with good morphology was obtained, but the layer was found to contain a considerable amount of carbon impurity originating from TEAs. The use of TEAs with 10% AsH3 or with 20% ammonia (NH3) apparently improves the quality of GaAs layer. A possible scheme for reducing carbon incorporation is discussed.
The thermolysis of dicarbonylcyclopentadienyliron dimer: The formation of biferrocene
Authors: Wilkie Charles A , Huettl Brian
Published: January 2005

The thermolysis of dicarbonylcyclopentadienyliron dimer in a sealed tube at 300°C has been reported to produce ferrocene, carbon monoxide, carbon dioxide, cyclopentadiene and elemental iron. We observe in addition to these products the production of biferrocene and elemental carbon. Thermolysis of carbonylcyclopentadienyliron tetramer (produced from the dimer by thermolysis in refluxing xylene) produces ferrocene, iron and carbon monoxidre; no biferrocene, carbon dioxide or elemental carbon are produced. A scheme is proposed to account for these products.
Polarographic behaviour of some organotin(IV) compounds in dimethyl sulphoxide
Authors: Al‐Allaf Talal A K , Sulaiman Sadallah T , Hameed Yasser O
Published: January 2005

The differential pulse polarographic behaviour in dimethyl sulphoxide (DMSO) of 14 organotin(IV) compounds having the general formula R3SnX (R = Me, Ph; X− = NCS−, N3−, N3−, NO3−, OH−, NCO− and OAc−) and nBu3SnCl and nBu2SnCl2 has been studied. The peak potential was found to depend markedly on the organic group and to a lesser extent on the nature of the anion X. The phenyltin compounds were reduced at lower potentials than the corresponding methyltin compounds. The data obtained could be used for trace determination of these compounds. Linear calibration curves were obtained over the concentration range of 2.8 × 10−4 to 1.9 × 10−6 mol dm−3.
Butyltins in california river and lake marina waters
Authors: Stang Peter M , Goldberg Edward D
Published: January 2005

Butyltins were analyzed in waters from California river and lake marinas and were detected at the part per trillion (ppt) level in most locations. The tributyltin:dibutyltin (TBT/DBT) ratios in the fresh waters were similar to those in their saline counterparts indicating like rates of degradation in the two salinity regimes.
The preparation and structure of 1,4,5,6,7,7‐hexachloro‐2‐endo‐ferrocenylhydroxymethyl‐3‐endo‐hydroxymethyl‐5‐norbornene
Authors: Carty P , Grant J , Metcalfe E , Povey D C
Published: January 2005

The crystal structure of a novel ferrocene derivative with potential flame‐retardant/smoke‐suppressant activity, 1,4,5,6,7,7‐hexachloro‐2‐endo‐ferrocenyl‐hydroxymethyl‐3‐endo‐hydroxymethyl‐5‐norbornene, has been determined. Some of the carbon–carbon bonds within the chlorendic residue are unusually long, and there is no interaction between the hydroxyl groups and the iron atom. There is evidence of intramolecular hydrogen bonding between the two hydroxyl groups.
Organogallium compounds from metallic gallium through using metal‐vapor synthesis
Authors: Starowieski Kazimierz B , Klabunde Kenneth J
Published: January 2005

The first syntheses of organogallium compounds utilizing metallic gallium and alkyl halides (bromides and iodides) are presented. Metal‐vapor synthesis methods were used, and it is proposed that gallium atoms are the reactive species involved.

Gallium also reacted with alkyl halides as fine particles in slurry form, but only when deposited in, or co‐deposited with, alkylaluminum compounds. Rationale for this finding is based on irregularity of the clusters due to incorporation of aluminum (or its compounds) and probably also on smaller particle sizes.
Tributyltin determination in marine sediments: A comparative study of methods
Authors: Astruc A , Lavigne R , Desauziers V , Pinel R , Astruc M
Published: January 2005

Two independent speciation methods have been applied to the determination of tributyltin (TBT) in marine sediments: (1) acetic acid leaching/hydride generation/cold trapping/GC/quartz furnace AA; and (2) toluene–tropolone extraction/HPLC/GFAA. TBT determines in a typically moderately polluted sediment (Porto Vecchio Bay, Corsica, France) are in very good agreement, as also are the determination of total recoverable tin by the first method and by a direct one using strong acid leaching followed by GFAA. These cross‐verifications lead one to conclude that both speciation methods are convenient and allow for valid determination of TBT in marine sediments, with no loss of TBT. Method‐induced modification of tin speciation has not been observed.
Insecticidal activity of some penta‐ and hexa‐coordinated heterocyclic β‐diketone derivatives of diorganotin(IV) against the stored product pest Rhizopertha (Coleoptera: Bostrichidae)
Authors: Saxena Prabhu N , Saxena Sanjiv
Published: January 2005

Some new penta‐and hexa‐coordinated diorganotin complexes of heterocyclic β‐diketones having the general formula (n‐C4H9)2Sn(OPr1)2−n[RCOC:CON(C6H5) N:CCH3]n (where RCH3, C6H5 and p‐ClC6H4 and n = 1 and 2) have been synthesized and were screened for their insecticidal activity against Rhizopertha dominica (Fabricius), the lesser grain borer. The hexa‐coordinated complexes have been observed to be more active than the penta‐coordinated complexes.
Effect of six triorganotin(IV) compounds on nitrification and ammonification in soil
Authors: Kuthubutheen A J , Wickneswari R , Kumar Das V G
Published: January 2005

The effects of six triorganotin(IV) compounds and of Thiram on nitrification and ammonification in soil were investigated. Low concentrations of up to 50 μg g−1 of the triorganotin(IV) compounds enhanced nitrate‐nitrogen (NO3−‐N) production in soil. Except for diphenylbutyltin bromide, which inhibited nitrification at 250 μg g−1, the other triorganotin(IV) compounds were inhibitory at concentrations of 100 μg g−1 to less than 250 μg g−1. At 10 μg g−1, only triphenyltin acetate was less inhibitory towards nitrification compared with Thiram. At 250 μg g−1, Thiram exerted a strongly persistent inhibitory effect towards nitrification. The NO3−‐N level recorded 28 days after application was only 0.10 μg g−1 soil. With the triorganotin compounds NO3−‐N levels of 7.05–12.06 μg g−1 soil were recorded 28 days following their application. The deleterious effects of the triorganotin(IV) compounds were less persistent and recovery of nitrification was evident seven days after application. Low concentrations of Thiram and triorganotin(IV) compounds inhibited ammonification, whereas higher concentrations enhanced ammonification. Complete inhibition of ammonification was attained 21–28 days after application of Thiram at 50 μg g−1. On the other hand, with the triorganotin(IV) compounds, except for diphenylbutyltin bromide at 10–50 μg g−1, ammonification persisted at all concentrations 28 days after application.
Laser photochemistry of organometallic compounds related to applications in microelectronics
Authors: Sato Hiroyasu
Published: January 2005

Photochemistry of organometallic compounds achieves a marriage of a rich variety of organometallic chemistry and the full potential of electronically excited states of molecules. The application of lasers as light sources adds a great many new features to these studies, which cannot be attained by other means, because lasers provide light of such a high quality, e.g. a high‐intensity, energetic (i.e. wavelength) purity, a high degree of coherence, and a high spatial and temporal resolution. Laser photochemistry of organometallic compounds, such as laser photochemical vapor deposition (LPCVD), laser ablation, and photochemical dry etching, forms the basis of many important industrial processes which sustain the present‐day microelectronics industries. Lasers are used not only to photodissociate organometallic molecules, but to monitor the reaction steps by probing the starting material, chemical intermediate, or final product by many laser‐based spectroscopic methods. Although it is a very young area of science (the first laser was operated in 1960), this research area is now really ebullient, as a result of strong interest from both the fundamental and the practical sides. Laser photochemistry of organometallic compounds extends a wide and fertile research frontier, full of challenge and novel possibilities. In the present review, the present status of laser (ultraviolet and visible) photochemistry of organometallic compounds related to these industrial applications is briefly reviewed, with special emphasis on the basic studies of the relevant photochemistry and their relationship to photochemical processes on solid surfaces.
Stratification and tributyltin variability in San Diego Bay
Authors: Stang Peter M , Bower David R , Seligman Peter F
Published: January 2005

Tributyltin (TBT), a biocidal antifoulant in many marine paints, was measured in near‐surface and near‐bottom water over a 25 h period at the entrance to a marina in San Diego Bay, USA. Surface water concentrations varied from 20 to 225 nanograms per liter (ng dm−3) as TBT chloride and bottom water varied from non‐detectable (<1 ng dm−3) to 77 ng dm−3. Surface water concentrations varied, with highest concentrations associated with ebbing tides, and lowest concentrations with flooding tides, indicating that the yacht basin is a source of TBT. Bottom water TBT concentrations were almost always lower than corresponding surface water concentrations. The highest bottom water concentrations were associated with flooding tides and lowest surface water TBT concentrations. Physical water column measurements indicate that vertical stratification developed during ebbing tides and dissipated during flooding tides. This accounted for maximum bottom water and minimum surface water TBT concentrations during flooding tides, due, at least in part, to vertical mixing and dilution during flood tides.
Preparation and properties of triorganostannylmethyl 2,3:5,6‐di‐O‐isopropylidene‐α‐D‐mannofuranosides; pesticidal and fungicidal activities of triphenylstannyl‐carbohydrate derivates
Authors: McDonough Christine R , Taylor Oonah J , Wardell James L
Published: January 2005

The synthesis of trioganostannylmethyl 2,3:5,6‐di‐O‐isopropylidene‐α‐D‐mannofuranoside (compound 3, R*OCH2SnR2R′:RR′Me or Ph) from D‐mannose is reported. The compound 3 (RR′Ph) is transmetallated by PhLi to compound 5, R*OCH2Li, Which can be trapped by HgCl2 [as (R*OCH2)2Hg] and by ketones, R3COMe [as compound 7, R*OCH2CR3MeOH]. Two stereoisomers of this compound (7a, R3Ph) were formed in a ratio of 40:60, indicating some asymmetric induction, arising from the chiral R* moiety. Reactions of compound 3, (RR′Ph), with I2, HO2CCF3 and Cl2PtCOD result in Ph–Sn bond cleavage and formation of compound 3 with RPh; R′I, OCOCF3 and Cl respectively. Reactions of compound 3 (RR′Me) with electrophiles can lead to cleavage of either of both types of C–Sn bonds present (e.g. by I2, Br2, Cl2PtCOD or SnCl4) or to attack at the C5–C6 protecting group with release of acetone (e.g. by CF3CO2H, SO2 or CH3COCl). Pesticidal and fungicidal activities of compound 3(RR′Ph) as well as of 1,2:5,6‐di‐O‐isopropylidene‐3‐O(triphenylstannylmethyl)‐α‐D‐glucofuranose (compound 2, RPh) and methyl 4, 6‐O‐benzylidene‐2‐deoxy‐2‐triphenylstannyl‐α‐D‐altropyranoside (compound 1, RPh) are reported.
Assessment of the in vitro broad‐spectrum antiviral activity of some selected antitumor organotin complexes
Authors: Ward Sarah G , Taylor R Craig , Crowe Alan J , Balzarini Jan , De Clercq Erik
Published: January 2005

Eleven antitumor‐active octahedral organotin complexes of the type R2SnX2L2, where R = methyl, ethyl or phenyl, X = chloride or bromide, and L2 = o‐phenantholine ((phen), 2‐)2‐(pyridyl)‐benzimidazole (PBI) or two dimethylsulfoxides (2DMSO), were examined for their broad‐spectrum in vitro antiviral activity against a number of DNA and RNA viruses. The DNA viruses included in this study were herpes simplex virus type 1 and type 2, a TK–(thymidine kinase deficient) strain of herpes simplex virus type 1, and vaccinia virus. The RNA viruses were vesicular stomatitis virus, Coxsackie virus type B4, Sindbis virus, Semliki forest virus, parainfluenza virus type 3, and human immunodeficiency virus (HIV). Overall, the complexes showed weak antiviral activity and low selectivity. With the exception of (CH3)2SnBr2·PBI and (C6H5)2SnCl2·2DMSO, all of the complexes were active against one or more of the three strains of herpes simplex viruses. On the other hand, only three complexes, (CH3)2SnBr2·PBI, (CH3)2SnBr2·phen, and (C6H5)5SnBr2·PBI, exhibited marginal activity against some of the RNA viruses. None of the complexes was active against vesicular stomatitis or parainfluenza virus. Similarly, there was no inhibitory activity towards HIV‐1‐associated reverse transcriptase or HIV‐1‐induced cytopathogenicity in human T‐lymphocyte MT4 cell cultures at subtoxic concentrations.