bluuebunny/crossref_metadata_2025 huggingface dataset:
Valorisation of palm by‐products as functional components
Authors: Tan Yew‐Ai , Sambanthamurthi Ravigadevi , Sundram Kalyana , Wahid Mohd Basri
Published: March 2007

Valorisation of palm by‐products increases business opportunities for stakeholders in the palm oil industry. The approach also paves the way for structuring an eco‐efficient industry that recognises the importance of sustainable development for continued growth and competitiveness. Research underway in the palm oil industry has revealed a range of bioactives that can be used as functional components for food products that enhance health. Crude palm oil with 500–700 mg/kg of carotenes is one of the richest plant sources of provitamin A. Tocopherols and tocotrienols are also present in the oil at significant levels of between 600 and 1000 mg/kg. Besides the oil, by‐products of palm oil milling and refining also contain bioactives. Tocopherols and tocotrienols are concentrated in the palm fatty acid distillate (PFAD), a by‐product of physical refining of palm oil. Sterols and squalene can also be recovered from PFAD. Palm pressed fibres contain extractable phytochemicals such as sterols, vitamin E, carotenoids, phospholipids, squalene and phenolics. Water‐soluble palm phenolics have been successfully extracted from aqueous by‐products generated from the mill. These palm extracts show superior antioxidant potential and are earmarked for applications in functional foods, nutraceuticals, pharmaceuticals and cosmeticeuticals.
Palm oil and palm kernel oil as raw materials for basic oleochemicals and biodiesel
Authors: Rupilius Wolfgang , Ahmad Salmiah
Published: March 2007

The palm oil‐ and palm kernel oil‐producing countries in South East Asia are becoming the dominant producers of fatty acids and fatty alcohols. The large and very efficient palm oil plantations are giving the local producers of basic oleochemicals a decisive competitive advantage. The production of fatty acid methyl esters for use as biodiesel is expanding all around the world. In tropical countries, the preferred raw material for biodiesel is palm oil, Europe uses mostly low‐erucic rapeseed oil and the USA soya oil. To a large extent, the growth of biodiesel depends on direct or indirect subsidies for the agriculture and on tax exemptions. The rapid growth of biodiesel has created an excess of glycerine, which cannot be absorbed by existing markets. The price for glycerine will probably remain low for the next years and therefore attract investments in new applications.
Synthesis and Spectral Properties of Amphiphilic Lipids with Linear Conjugated Polyene and Phenylpolyene Fluorescent Groups
Authors: Quesada Ernesto , Delgado Javier , Hornillos Valentín , Acuña A. Ulises , Amat‐Guerri Francisco
Published: March 2007

Lipophilic fluorescent groups with a chain‐like linear conformation emitting in the visible range and with high photostability are presently unavailable. These structures would be of great interest as labels for long‐chain fatty acids and phospholipids lacking intrinsic fluorescent groups. With this aim in mind, we report the synthesis and the spectroscopic characterization of a series of emitting amphiphilic lipids that may approach that ideal fluorescent tag. Each lipid was constructed by attaching a linear, all‐(E) conjugated pentaene, tetraenyne, ω‐phenyltetraene, or ω‐phenyltrienyne chromophore to a hydrophilic head‐group through a polymethylene chain spacer. The key steps of the synthesis were the Pd0‐mediated cross‐coupling reaction between bromopolyenes and terminal acetylenic compounds, yielding tetraenynes or ω‐phenyltrienynes, and the subsequent triple‐bond partial reduction, producing the corresponding pentaenes or ω‐phenyltetraenes in good overall yields. This method represents a further successful example of the so‐called “acetylenic approach” to the indirect high‐yield synthesis of polyene systems. In the case of ω‐phenyltrienynes, a higher proportion of the all‐(E) isomer was obtained using an alternative method based on the reaction of an ω‐phenyldienylphosphonate with an α‐acetylenic aldehyde. Some of the resulting compounds exhibit spectral and photochemical properties that warrant their use as emitting lipophilic tags. Thus, the ω‐phenyltetraene and ω‐phenyltrienyne members of the series show intense absorption bands in the 320–370 nm range with fluorescence emission centered at 475 nm and quantum yields up to 0.25. These parameters are appropriate for the applications noted above. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Comprehensive Kinetic and Mechanistic Considerations for the Gas‐Phase Behaviour of Pinane‐Type Compounds
Authors: Stolle Achim , Ondruschka Bernd , Bonrath Werner
Published: March 2007

The thermal behaviour of selected pinane‐type compounds, α‐pinene (1), β‐pinene (2), pinane (3) and nopinone (4), has been investigated. The conversion of the bicyclic starting materials to their acyclic and monocyclic isomers as well as the consecutive reactions of the acyclic main isomerisation products are discussed. The conversion of 1–4 in a reaction network is presented and the experimental evidence for the formation of pyrolysis products by a biradical pathway is discussed. In addition to these results a kinetic model describing the isomerisation of the bicyclic compounds to their acyclic and monocyclic isomers is presented. A good correlation between kinetic simulations and experimental data is revealed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Photo‐ and Proton‐Dual‐Responsive Fluorescence Switch Based on a Bisthienylethene‐Bridged Naphthalimide Dimer and Its Application in Security Data Storage
Authors: Jiang Guiyuan , Wang Sheng , Yuan Wenfang , Zhao Zhen , Duan Aijun , Xu Chunming , Jiang Lei , Song Yanlin , Zhu Daoben
Published: March 2007

A photo‐ and proton‐dual‐responsive fluorescence switch based on a bisthienylethene‐naphthalimide dimer was described. Security data storage based on this dual‐responsive fluorescent molecular switch was proposed and demonstrated. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Intermolecular FeCl3‐Catalyzed Hydroamination of Styrenes
Authors: Michaux Julien , Terrasson Vincent , Marque Sylvain , Wehbe Johny , Prim Damien , Campagne Jean‐Marc
Published: March 2007

Hydroamination reactions of vinylarenes with nonnucleophilic nitrogen derivatives (p‐toluenesulfonamide, p‐nitroaniline, p‐nitrobenzamide, ...) catalyzed by FeCl3 are described. Interestingly, these reactions are catalyzed by an environmentally friendly and an inexpensive catalyst in the absence of any ligand or cocatalyst. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Review of the literature examining the correlation among DNA microarray technologies
Authors: Yauk Carole L. , Berndt M. Lynn
Published: March 2007

DNA microarray technologies are used in a variety of biological disciplines. The diversity of platforms and analytical methods employed has raised concerns over the reliability, reproducibility and correlation of data produced across the different approaches. Initial investigations (years 2000–2003) found discrepancies in the gene expression measures produced by different microarray technologies. Increasing knowledge and control of the factors that result in poor correlation among the technologies has led to much higher levels of correlation among more recent publications (years 2004 to present). Here, we review the studies examining the correlation among microarray technologies. We find that with improvements in the technology (optimization and standardization of methods, including data analysis) and annotation, analysis across platforms yields highly correlated and reproducible results. We suggest several key factors that should be controlled in comparing across technologies, and are good microarray practice in general. Environ. Mol. Mutagen., 2007. © 2007 Wiley‐Liss, Inc.
Evaluation of river water genotoxicity using the piscine micronucleus test
Authors: Ergene Serap , Çavaş Tolga , Çelik Ayla , Köleli Nurcan , Aymak Cemil
Published: March 2007

The Berdan River, which empties into the Mediterranean Sea on the east coast of Turkey, receives discharges of industrial and municipal waste. In the present study, the in vivo piscine micronucleus (MN) test was used to evaluate the genotoxicity of water samples collected from different locations along the Berdan River. Nile tilapia (Oreochromis niloticus) were exposed in the laboratory for 2, 4, and 6 days, and micronuclei were evaluated in peripheral blood erythrocytes, gill cells, and caudal fin epithelial cells. A single dose of 5 mg/L cyclophosphamide was used as a positive control. In addition to micronuclei, nuclear abnormalities (NAs), such as binucleated cells and blebbed, notched, and lobed nuclei, were assessed in the erythrocytes, and chemical analyses were carried out to determine the amount of heavy metals in the water samples. MN and NA frequencies were significantly elevated (up to 2‐ to 3‐fold) in fish exposed to river water samples taken downstream of potential discharges, and the elevated responses in gill and fin cells were related to the concentration of heavy metals in the water. MN frequencies (expressed as micronucleated cells/1,000 cells), in both treated and untreated fish, were greatest in gill cells (range: 0.80–3.70), and generally lower in erythrocytes (range: 0.50–2.80), and fin cells (range: 0.45–1.70). The results of this study indicate that the Berdan River is contaminated with genotoxic pollutants and that the genotoxicity is related to the discharge of wastes into the river water. Environ. Mol. Mutagen., 2007. © 2007 Wiley‐Liss, Inc.
Semiparametric zero‐inflated Poisson models with application to animal abundance studies
Authors: Chiogna Monica , Gaetan Carlo
Published: March 2007

This paper describes a framework for flexibly modeling zero‐inflated data. Semiparametric regression based on penalized regression splines for zero‐inflated Poisson models is introduced. Moreover, an EM‐type algorithm is developed to perform maximum likelihood estimation. As an illustration, a study of animal abundance is tackled. In fact, abundance often shows excess of zeroes and is a complicated function of the explanatory variables. In particular, the relationships between avian abundance and environmental variables indicating land use are tackled. Copyright © 2007 John Wiley & Sons, Ltd.
Dynamics of towers surrounded by water
Authors: Liaw C‐Y. , Chopra Anil K.
Published: March 2007

The effects of interaction with surrounding water on the dynamic response behaviour of cantilever tower structures are studied. Expressions for response to harmonic ground motion in individual modes of vibration, including hydrodynamic interaction, are presented, the accuracy of responses obtained by ignoring surface waves and compressibility of water in the hydrodynamic solutions is evaluated, the effects of hydrodynamic interaction on the fundamental period of vibration are studied and the commonly used ‘added mass’ approach to account for effects of surrounding water is examined. The conclusions deduced from the results of this investigation include the following. Interaction with surrounding water increases the fundamental period of vibration of the tower and decreases the modal damping ratio. Compressibility of water has essentially no influence in the hydrodynamic effects on slender towers. The traditional definition of added mass is conceptually deficient, but is simple to employ; the errors in this simple added mass representation are negligible for the first mode of vibration of towers.
A numerical study of damping
Authors: Thomson William T. , Calkins Tom , Caravani Paolo
Published: March 2007

Diagonal damping matrices were computed for three systems which have non‐proportional damping matrices. These diagonal damping matrices were computed on three bases, as follows: 1. After normalizing the equations of motion by the modal matrix, the diagonal terms are retained ignoring the non‐diagonal terms. 2. Diagonal damping matrix is established by the optimization algorithm which minimizes the mean square error of the frequency response. 3. Diagonal damping is determined from the normalized differential equation by matching the peaks of the coupled and uncoupled system.

The frequency responses for the three cases of one of the three systems are presented together with a comparison of the energy dissipation.
Dynamic behaviour of building‐foundation systems
Authors: Veletsos Anestis S. , Meek Jethro W.
Published: March 2007

A discussion of the effects of soil‐structure interaction on the dynamic response of linear structures which respond as single‐degree‐of‐freedom systems in their fixed‐base condition is presented. The structures are presumed to be supported at the surface of a homogeneous, elastic halfspace and to be excited at the base. The free‐field ground motions investigated include a harmonic motion, a relatively simple pulse‐type excitation and an actual earthquake record. Comprehensive response spectra are presented for a range of the parameters defining the problem, and the results are used to assess the accuracy of a simple, approximate method of analysis in which the system is represented by a viscously damped, simple oscillator. Special attention is given to defining the conditions under which the interaction effect is of sufficient importance to warrant consideration in design. The method of analysis used to obtain the numerical data reported herein is reviewed only briefly, the emphasis of the paper being on the interpretation of the results.
A comparative study of bounding techniques in dynamic shakedown of elasto‐plastic structures
Authors: Corradi Leone , Nova Roberto
Published: March 2007

Two conceptually different procedures to obtain upper bounds to displacements and deformations developed in the dynamic evolution of elasto‐plastic structures are considered. Computationally, both methods require the dynamic analysis of a linear system and a sequence of constrained optimization problems, each roughly analogous to a limit analysis procedure in the quasi‐static range, with a substantial saving in effort when compared to an incremental analysis of the plasto‐dynamic response. A discrete model for frames is proposed and the two approaches are reformulated in a convenient matrix form. The approaches are then compared on the basis of the information needed (total or plastic displacements, deformations, dissipated energy), of the usefulness of results obtained and of the computational effort involved. The results seem to indicate the practical usefulness of these techniques and encourage the extension of the study to broader classes of structures.
Scattering of plane sh waves by a semi‐elliptical canyon
Authors: Wong H. L. , Trifunac M. D.
Published: March 2007

In this paper we analyse the two‐dimensional scattering and diffraction of plane SH waves by a semi‐elliptical canyon. The exact series solution of the problem, for general angle of incidence of the plane SH waves, has been used to examine the dependence of surface amplifications inside and near the canyon. The nature of ground motion has been found to depend on two key parameters: (a) The angle of incidence. (b) The ratio of the canyon width to the wave length of incident SH waves.

For short incident waves surface displacement amplitudes change rapidly from one point to another, while for the long waves and shallow canyons displacement amplitudes display only minor departure from the uniform half‐space amplification of 2. For shallow canyons and long incident waves, the angle of incidence introduces only minor changes into the overall behaviour of surface amplitudes. For deep canyons and nearly grazing incidences, a prominent shadow zone is realized behind the canyon.
Ground vibrations due to seismic detonation in oil exploration
Authors: Awojobi A. O. , Sobayo O. A.
Published: March 2007

Previous works on this subject deal mainly with establishing an empirical relationship between the extent of the vibration at the building site (measured by the peak particle velocity), the distance of the building from the explosive, the energy content of the explosive and the frequency of detonating the explosives. These works are mainly limited to cases where the explosives are placed on the surface. However, the practical case requires that the explosive is considered to be buried, either on the sea‐bed in offshore operations or underground in land explorations. This practical case has hitherto received little attention.

The present work records an empirical relation based on field tests in Mid‐Western and Rivers States of Nigeria. The depth of the buried explosive is now introduced as an additional parameter and the empirical relation shows its effect, along with the above parameters, on the extent of vibrations at the surface. An interesting, and rather unexpected, stationary point is consistently observed in the variation of peak particle velocity at the surface as the depth of the buried explosive increases while other parameters are kept constant.
Earthquake analysis of axisymmetric towers partially submerged in water
Authors: Liaw C.‐Y. , Chopra Anil K.
Published: March 2007

A method for analysis of response of axisymmetric towers partly submerged in water to earthquake ground motion is presented. The tower is idealized as a finite element system. The hydrodynamic terms are determined by solving the Laplace equation, governing the dynamics of incompressible fluids, subject to appropriate boundary conditions. For cylindrical towers, these solutions are obtained as explicit mathematical solutions of the boundary value problems; whereas they are obtained by the finite element method in case of towers with non‐cylindrical outside surface. The response to earthquake ground motion is determined by step‐by‐step integration of the equations of motion. Analyses of two actual intake towers are presented to illustrate results obtained by this method. The small computation times required for these analyses demonstrate that the method is very efficient. The effectiveness of this formulation lies in avoiding the analysis of a large system by using a substructure approach and in exploiting the important feature that structural response to earthquake ground motion is essentially contained in the first few modes of vibration of the tower with no surrounding water.
Dynamic behaviour of structures with embedded foundations
Authors: Bielak Jacobo
Published: March 2007

A study of the dynamics of building‐soil interaction is presented that includes embedding of the foundation and material damping. By considering buildings on rigid footings embedded into linear elastic soil with hysteretic damping, it is shown that the earthquake response of the building‐foundation model may be found from the response to modified excitation of equivalent one‐degree‐of‐freedom linear, viscously damped oscillators resting on rigid ground. For a single‐storey building approximate formulas are developed for the modified natural frequency and damping ratio.

Results show that the natural frequency and damping in the system increase with embedding. Effective damping also increases with internal friction in the soil. Ignoring these two factors may underestimate considerably the effective natural frequency and damping in the system. In spite of additional sources of energy dissipation provided by the soil, damping in the equivalent oscillator may be greater or smaller than that corresponding to the superstructure alone, depending upon the system parameters.

For lightly damped superstructures, the peak amplitude of the steady‐state overturning moment at the base of a building supported on flexible soil is significantly smaller than that corresponding to rigid ground. This result has practical implications for earthquake design.
The effect of coulomb damping on multidegree of freedom elastic structures
Authors: Mayes R. L. , Mowbray N. A.
Published: March 2007

This paper is based on the premise that the damping mechanism of a multidegree of freedom structure can be represented by viscous and coulomb dampers. A closed form solution for the structure subjected to a sinusoidal forcing function is presented. The solution is used as the basis of a method for determining relative amounts of viscous and coulomb damping from vibration tests. The method was applied to the results of a series of vibration tests on a five storey reinforced concrete structure and approximate values of viscous and coulomb damping obtained. A comparison of the effect of various combined damping values on the earthquake response of the structure was made. It was concluded that the use of the equivalent viscous damping concept to approximate the combined effect of viscous and coulomb damping results in a low estimate of the elastic response of the structure.
Hysteretic dampers for earthquake‐resistant structures
Authors: Skinner R. I. , Kelly J. M. , Heine A. J.
Published: March 2007

The earthquake resistance of many structures can be increased by the inclusion of special components which act as hysteretic dampers. During moderately severe earthquakes these dampers act as stiff members which reduce structural deformations, while during very severe earthquakes the dampers act as energy absorbers which limit the quasi‐resonant build‐up of structural deformations and forces.

The hysteretic dampers are not required to withstand the main structural loads, and may therefore be optimized for their required stiffness and energy‐absorbing features. On the other hand, the main structural components no longer require large energy‐absorbing capacities and they may therefore be optimized for their required stiffnesses and load‐bearing features.

For many structures this separation of component functions should lead to increased reliability at a lower initial cost. Under earthquake attack structural damage should be reduced. Non‐structural damage should be lower during moderately severe earthquakes, and for certain types of structure it should also be lower for very severe earthquakes.

Various ways in which hysteretic dampers may be utilized in structures are discussed briefly.

The development of several types of high‐capacity, low‐cost hysteretic damper, suitable for use in structures, is described. The dampers utilize solid steel beams deformed plastically in various combinations of torsional, flexural and shear deformations.
A practical system for isolating structures from earthquake attack
Authors: Skinner R. I. , Beck J. L. , Bycroft G. N.
Published: March 2007

The recent development of a range of hysteretic energy absorbers permits practical shock isolation systems to be incorporated in the bases of a wide range of structures. This isolation gives reduced earthquake loads which may be resisted by the normal lateral strength of the structure. Hence a plastic reserve of earthquake resistance is no longer essential.

A wider choice of architectural and structural forms is available with such an isolation system. The structures may be designed to prevent structural and non‐structural damage with a high degree of reliability.

The special hysteretic dampers limit the lateral movement of the base of a structure to a few inches. With these small movements the lateral flexibility required for an isolating system can be conveniently provided, for many structures, by rubber bearings.
Additional note on the effect of soil on structural response
Authors: Novak Milos
Published: March 2007

The previous paper on this subject, Reference 1, is complemented here to include one additional effect of soil on structural response. This effect is the modification of the original structural damping, estimated under the assumption of rigid foundation, due to foundation flexibility. This can be of practical importance, particularly with heavily damped structures vibrating in the fundamental mode. With lightly damped structures, such as those assumed in Reference 1, this effect diminishes.
Seismic behaviour of above‐ground oil pipelines
Authors: Anderson James C. , Johnston Sterling B.
Published: March 2007

The dynamic behaviour of above‐ground oil pipelines which are allowed to slide back and forth on intermediate supports during strong motion earthquakes is studied. This sliding is resisted by friction between the pipe and the top of the support. The main objective of the study is to determine the effect of this non‐linear friction on both the static and dynamic stresses in the pipe. The study also considers the influence of other critical parameters such as: pipeline configuration, seismic wave velocity, initial temperature differential and internal pressure, and ground motion characteristics. Results show that the critical bending moments in the pipe occur during the static loading and that with seismic excitation, these moments tend to shake down as the pipe moves to a more stress free configuration. It is shown that the use of sliding friction can be an effective means of dissipating seismic energy and thereby damping the dynamic response of the pipeline even for low values of the coefficient of friction.
Induced torsional oscillations in symmetrical structures
Authors: Tso W. K.
Published: March 2007

A study is made on the torsional‐lateral motions of non‐linear symmetrical structures subjected to lateral ground motion. The torsional and lateral response of a single mass symmetrical system subjected to sinusoidal ground motion is investigated. The load‐displacement relationship of the resisting elements is taken to be weakly nonlinear of a softening type. It is shown that non‐linear coupling exists between the lateral and rotational motions. For sinusoidal lateral response, the torsional motion equation can be cast in the form of a Mathieu equation. The likelihood of induced torsional response is then studied in terms of unstable regions in the parametric amplitude‐frequency parameter space. The implication of this type of non‐linear torsional‐lateral coupling to the responses of real symmetrical structures subjected to actual earthquake ground motion is then discussed.
Stability of columns subjected to earthquake support motion
Authors: Mostaghel Naser
Published: March 2007

The problem of stability of an initially straight, simple column which is subjected to dynamic overload due to the vertical component of ground acceleration during an earthquake is considered. The time history of this component of earthquake, its maximum absolute amplitude and a Liapunov's function are used to define a sufficient condition under which the column will always be stable. It is shown for the case of a simple column that this condition implies that the column will be stable as long as the maximum load which the column is subjected to is less than the Euler buckling load during an earthquake.
Dynamic response of a staggered wall‐beam structure
Authors: Mee A. L. , Jordaan I. J. , Ward M. A.
Published: March 2007

A method for the dynamic analysis of staggered wall‐beam frames is developed using consistent mass terms which are derived and given in simple terms. The method uses effective stiffnesses for wall‐beam elements developed in an earlier paper. Experiments using a nine storey 1 : 15 scale perspex model are described. The first three natural frequencies of the model were obtained using two methods: sinusoidal external excitation of the structure with the base fixed and white noise excitation employing a single degree‐of‐freedom shake table, in the latter method with and without the addition of mass throughout the model. Agreement between analytical predictions of the first three natural frequencies and mode shapes and experimentally determined values is considered satisfactory, particularly for the first two modes. The lumped mass assumption gave reasonable results for these two cases, whereas the consistent mass theory gave reasonable results for the first three natural frequencies.
Non‐linear finite element dynamic analysis of axisymmetric solids
Authors: Nagarajan S. , Popov E. P.
Published: March 2007

The subject of this paper is the finite element analysis of axisymmetric solids subjected to axisymmetric static and dynamic loading, and taking into account material as well as geometric non‐linearities. A general Lagrangian formulation forms the basis for the incremental equations of motion which are solved using direct integration methods. Solution accuracy is improved by applying equilibrium correction loads at each step. Finite element discretization is achieved through the use of quadrilateral plane stress and axisymmetric elements with incompatible modes added for improvement of the element flexural characteristics. Several numerical examples are presented to demonstrate the effectiveness of the developed computer program.
Ground‐motion modelling at regional distances for earthquakes in a continental interior, I. Theory and observations
Authors: Herrmann Robert B. , Nuttli Otto W.
Published: March 2007

To understand the ground‐motion contribution by multiple‐mode surface‐wave arrivals, the surface‐wave theory required for predicting ground‐motion time histories is discussed. The adequacy of the theory in accounting for observed earthquake ground motion is tested by comparing theoretically predicted long‐period seismograms with real seismograms for two earthquakes in the central United States. The agreement between the predicted and observed maximum vertical component Lg ground velocities and accelerations in the 2‐ to 3‐sec period range is excellent over a distance range of 100 to 2,000 km.
Non‐linear models for simulating the dynamic damaging process of low‐rise reinforced concrete buildings during severe earthquakes
Authors: Takizawa Haruo
Published: March 2007

This paper is a study of idealizing a planar reinforced concrete frame as a non‐linear dynamic system for the purpose of simulating its inelastic behaviour during severe earthquakes. After having estimated the restoring force characteristics of all constituent members by experimental means (represented, for example, by a group of empirical equations), it is possible to estimate the non‐linear characteristics of the complete structure and to trace the damaging process for each constituent member under a given ground motion disturbance. However, this technique, which is directly based on member‐level properties, generally requires rather laborious computational procedures; for practical reasons it is necessary to develop a simplified model, reducing the required calculation without losing the substance of the mechanical phenomena. Thus the reliability of simplification by conventional shear modelling is examined in direct comparison with the response results from rigorous modelling. It is concluded that the shear modelling generally yields an inadequate and, in many cases, erroneous result. The primary cause leading to this discrepancy is identified and, based on this discussion, a more appropriate modelling as simple as conventional shear modelling is proposed.
Approximate natural frequencies for coupled shear walls
Authors: Rutenberg Avigdor
Published: March 2007

An approximate yet accurate formula is proposed for the natural frequencies of coupled shear walls under continuous medium assumptions. First the deflected shape of the structure is represented as the sum of two components: one due to flexural cantilever action and one due to shear‐flexure cantilever action. The natural frequencies of the latter two systems are then combined in Dunkerley's formula to yield the approximate frequency of the structure.
Blind signal reception in downlink time‐hopping ultrawideband communication system
Authors: Wu Wei‐Chiang
Published: March 2007

Ultra wideband (UWB) impulse radio (IR) system is currently being considered for several applications due to its attractive features that include low‐power carrierless modulation and ample multipath diversity. Among the various modulation and multiple‐access schemes, this paper deals with time‐hopping (TH) antipodal pulse amplitude modulation (PAM), operating in the presence of multipath‐fading downlink channel. We develop two types of low‐complexity mobile station (MS) receivers. One is based on the RAKE reception scheme and the other is designed to meet the minimum‐output‐energy (MOE) criterion. However, since accurate channel information is crucial for reliable operation, thereby we propose a blind (non‐data aided) channel estimator. Simulation results show that the MOE receiver outperforms the RAKE receiver in multiuser environment. Moreover, both the channel estimation algorithm and the MOE reception schemes are shown to be reliable and near‐far resistant. Copyright © 2007 John Wiley & Sons, Ltd.
Ship hydrodynamics computations with the CIP method based on adaptive Soroban grids
Authors: Takizawa Kenji , Tanizawa Katsuji , Yabe Takashi , Tezduyar Tayfun E.
Published: March 2007

The constrained interpolation profile/cubic interpolated pseudo‐particle (CIP) combined unified procedure (CCUP) method (J. Phys. Soc. Jpn. 1991; 60:2105–2108), which is based on the CIP method (J. Comput. Phys. 1985; 61:261–268; J. Comput. Phys. 1987; 70:355–372; Comput. Phys. Commun. 1991; 66:219–232; J. Comput. Phys. 2001; 169:556–593) and the adaptive Soroban grid technique (J. Comput. Phys. 2004; 194:55–77) were combined in (Comput. Mech. 2006; published online) for computation of 3D fluid–object and fluid–structure interactions in the presence of free surfaces and fluid–fluid interfaces. Although the grid system is unstructured, it still has a very simple data structure and this facilitates computational efficiency. Despite the unstructured and collocated features of the grid, the method maintains high‐order accuracy and computational robustness. Furthermore, the meshless feature of the combined technique brings freedom from mesh moving and distortion issues. In this paper, the combined technique is extended to ship hydrodynamics computations. We introduce a new way of computing the advective terms to increase the efficiency in that part of the computations. This is essential in ship hydrodynamics computations where the level of grid refinement needed near the ship surface and at the free surface results in very large grid sizes. The test cases presented are a test computation with a wave‐making wedge and simulation of the hydrodynamics of a container ship. Copyright © 2007 John Wiley & Sons, Ltd.
Efficient solution techniques for implicit finite element schemes with flux limiters
Authors: Möller M.
Published: March 2007

The algebraic flux correction (AFC) paradigm is equipped with efficient solution strategies for implicit time‐stepping schemes. It is shown that Newton‐like techniques can be applied to the nonlinear systems of equations resulting from the application of high‐resolution flux limiting schemes. To this end, the Jacobian matrix is approximated by means of first‐ or second‐order finite differences. The edge‐based formulation of AFC schemes can be exploited to devise an efficient assembly procedure for the Jacobian. Each matrix entry is constructed from a differential and an average contribution edge by edge. The perturbation of solution values affects the nodal correction factors at neighbouring vertices so that the stencil for each individual node needs to be extended. Two alternative strategies for constructing the corresponding sparsity pattern of the resulting Jacobian are proposed. For nonlinear governing equations, the contribution to the Newton matrix which is associated with the discrete transport operator is approximated by means of divided differences and assembled edge by edge. Numerical examples for both linear and nonlinear benchmark problems are presented to illustrate the superiority of Newton methods as compared to the standard defect correction approach. Copyright © 2007 John Wiley & Sons, Ltd.
Dynamics of Jovian atmospheres with applications of nonlinear singular vector method
Authors: Zhang Zhiyue , Lin Jing
Published: March 2007

Nonlinear singular vectors (NSVs) of a Jovian atmosphere model are obtained numerically in this paper. NSVs are the initial perturbation, whose nonlinear evolution attains the maximal value of the cost function, which is constructed according to the physical problem of interest. The results demonstrate that the motions of Jupiter's atmosphere is relatively stable under some assumptions. Copyright © 2007 John Wiley & Sons, Ltd.
The (9,5) HOC formulation for the transient Navier–Stokes equations in primitive variable
Authors: Kalita Jiten C. , Sen Shuvam
Published: March 2007

We recently proposed an improved (9,5) higher order compact (HOC) scheme for the unsteady two‐dimensional (2‐D) convection–diffusion equations. Because of using only five points at the current time level in the discretization procedure, the scheme was seen to be computationally more efficient than its predecessors. It was also seen to capture very accurately the solution of the unsteady 2‐D Navier–Stokes (N–S) equations for incompressible viscous flows in the stream function–vorticity (ψ – ω) formulation.

In this paper, we extend the scope of the scheme for solving the unsteady incompressible N–S equations based on primitive variable formulation on a collocated grid. The parabolic momentum equations are solved for the velocity field by a time‐marching strategy and the pressure is obtained by discretizing the elliptic pressure Poisson equation by the steady‐state form of the (9,5) scheme with the Neumann boundary conditions. In particular, for pressure, we adopt a strategy on the collocated grid in conjunction with ideas borrowed from the staggered grid approach in finite volume. We first apply this extension to a problem having analytical solution and then to the famous lid‐driven square cavity problem. We also apply our formulation to the backward‐facing step problem to see how the method performs for external flow problems. The results are presented and are compared with established numerical results. This new approach is seen to produce excellent comparison in all the cases. Copyright © 2007 John Wiley & Sons, Ltd.
A continuous second‐order sensitivity equation method for time‐dependent incompressible laminar flows
Authors: Ilinca F. , Pelletier D. , Borggaard J.
Published: March 2007

This paper presents a general formulation of the continuous sensitivity equation method (SEM) for computing first‐ and second‐order sensitivities of time‐dependent, incompressible laminar flows. The formulation accounts for complex parameter dependence and is suitable for a wide range of problems. The SEM formulation is verified on a problem with a closed‐form solution. Systematic grid convergence studies confirm the theoretical rates of convergence in both space and time. The methodology is then applied to uniform flow around a circular cylinder. The flow starts with a symmetrical solution and transitions to the traditional Von Karman street (alternate vortex shedding). Sensitivities are used to demonstrate fast evaluation of nearby flows. The accuracy of nearby flows is much improved when second‐order sensitivities are used. The sensitivity of the Strouhal number with respect to the Reynolds number agrees well with the computed and experimentalSt–Rerelationship. Copyright © 2007 John Wiley & Sons, Ltd.
A comparative study of inflow conditions for two‐ and three‐dimensional spatially developing mixing layers using large eddy simulation
Authors: McMullan W. A. , Gao S. , Coats C. M.
Published: March 2007

A series of spatially developing mixing layers are simulated using the large eddy simulation (LES) technique. A hyperbolic tangent function and data derived from boundary layer simulations are used to generate the inflow condition, and their effects on the flow are compared. The simulations are performed in both two and three dimensions. In two‐dimensional simulations, both types of inflow conditions produce a layer that grows through successive pairings of Kelvin–Helmholtz (K–H) vortices, but the composition ratio is lower for the hyperbolic tangent inflow simulations. The two‐dimensional simulations do not undergo a transition to turbulence. The three‐dimensional simulations produce a transition to turbulence, and coherent structures are found in the post‐transition region of the flow. The composition ratio of the three‐dimensional layers is reduced in comparison to the counterpart two‐dimensional runs. The mechanisms of growth are investigated in each type of simulation, and amalgamative pairing interactions are found in the pre‐transition region of the three‐dimensional simulations, and throughout the entire computational domain of those carried out in two‐dimensions. The structures beyond the post‐transition region of the three‐dimensional simulations appear to behave in a much different manner to their pre‐transition cousins, with no pairing‐type interactions observed in the turbulent flow. In order to accurately simulate spatially developing mixing layers, it is postulated that the inflow conditions must closely correspond to the conditions present in the reference experiment. Copyright © 2007 John Wiley & Sons, Ltd.
Assessment of the clinical and molecular impact of different cytogenetic subgroups in a series of 272 lipomas with abnormal karyotype
Authors: Bartuma Hammurabi , Hallor Karolin H. , Panagopoulos Ioannis , Collin Anna , Rydholm Anders , Gustafson Pelle , Bauer Henrik C. F. , Brosjö Otte , Domanski Henryk A. , Mandahl Nils , Mertens Fredrik
Published: March 2007

Conventional lipomas harbor karyotypic changes that could be subdivided into four, usually mutually exclusive, categories: rearrangement, in particular through translocations, of chromosome bands 12q13‐15, resulting in deregulation of the HMGA2 gene, loss of material from or rearrangement of chromosome 13, supernumerary ring or giant marker chromosomes, and aberrations of chromosome band 6p21. In the present study, 272 conventional lipomas, two‐thirds of them deep‐seated, with acquired clonal chromosome changes were assessed with regard to karyotypic and clinical features. A nonrandom distribution of breakpoints and imbalances could be confirmed, with 83% of the cases harboring one or more of the previously known cytogenetic hallmarks. Correlation with clinical features revealed that lipomas with rings/giant markers were larger, occurred in older patients, were more often deep‐seated, and seemed to have an increased tendency to recur locally, compared with tumors with other chromosome aberrations. The possible involvement of the HMGA2 gene in cases that did not show any of the characteristic cytogenetic changes was further evaluated by locus‐specific metaphase fluorescence in situ hybridization (FISH) and RT‐PCR, revealing infrequent cryptic disruption of the gene but abundant expression of full length or truncated transcripts. By FISH, we could also show that breakpoints in bands 10q22‐23 do not affect the MYST4 gene, whereas breakpoints in 6p21 or 8q11‐12 occasionally target the HMGA1 or PLAG1 genes, respectively, also in conventional lipomas. © 2007 Wiley‐Liss, Inc.
Delineation of a 1Mb breakpoint region at 1p13 in Wilms tumors by fine‐tiling oligonucleotide array CGH
Authors: Natrajan Rachael , Williams Richard D. , Grigoriadis Anita , Mackay Alan , Fenwick Kerry , Ashworth Alan , Dome Jeffrey S. , Grundy Paul E. , Pritchard‐Jones Kathy , Jones Chris
Published: March 2007

Wilms tumor karyotypes frequently exhibit recurrent, large‐scale chromosomal imbalances, among the most common of which are concurrent loss of 1p and gain of 1q. We have previously identified a novel breakpoint at 1p13 by 1 Mb‐spaced array CGH, and have now undertaken a fine‐tiling oligonucleotide array approach to map the region accurately in four tumors exhibiting rearrangements at this locus. The use of a 10 bp‐spaced platform revealed that all four tumors in fact harbored different breakpoints, which targeted intragenic sequences in PHTF1, DCLRE1B, and NRAS, and an intergenic region immediately downstream of TRIM33. All four genes and breakpoints were within the 1.78 Mb intervals identified by the genome‐wide BAC arrays. The precise breakpoint interval was in each case mapped to a 200–1,200 bp region and was confirmed for one case to lie within intron 3 of DCLRE1B by quantitative PCR. Analysis of local genome architecture revealed no convincing conservation of repetitive sequences or specific translocation/recombination‐associated elements within the breakpoint regions. This study highlights the power of fine‐tiling oligonucleotide arrays to delineate breakpoint regions identified by genome‐wide screens. © 2007 Wiley‐Liss, Inc.
Extrahippocampal gray matter atrophy and memory impairment in patients with medial temporal lobe epilepsy
Authors: Bonilha Leonardo , Alessio Andréa , Rorden Chris , Baylis Gordon , Damasceno Benito P. , Min Li Li , Cendes Fernando
Published: March 2007

Memory impairment observed in patients with medial temporal lobe epilepsy (MTLE) is classically attributed to hippocampal atrophy. The contribution of extrahippocampal structures in shaping memory impairment in patients with MTLE is not yet completely understood, even though atrophy in MTLE extends beyond the hippocampus. We aimed to evaluate the neuropsychological profile of patients with MTLE focusing on memory, and to investigate whether gray matter concentration (GMC) distribution within and outside the medial portion of the temporal lobes would be associated with their neuropsychological performance. We performed a voxel based morphometry study of 36 consecutive patients with MTLE and unilateral hippocampal atrophy. We observed a significant simple regression between general and verbal memory performance based on Wechsler Memory Scale—Revised and the GMC of medial temporal and extratemporal structures in patients with left MTLE. We also performed a “regions of interest analysis” of the medial temporal lobe, and we observed that the GMC of the hippocampus, entorhinal, and perirhinal cortices were consistently associated with general and verbal memory performance in patients with MTLE. We also observed that the GMC of the cingulate and orbito‐frontal cortex are independently associated with verbal and general memory performances. Our results suggest that general and verbal memory impairments in patients with left MTLE are associated with atrophy of the hippocampus, the entorhinal, and the perirhinal cortex. We also suggest that atrophy and dysfunction of limbic and frontal structures such as the cingulate and the orbito‐frontal cortex contribute to memory impairment in MTLE. Hum Brain Mapp 2007. © 2007 Wiley‐Liss, Inc.