bluuebunny/crossref_metadata_2025_split huggingface dataset:
Generalized strain probing of constitutive models
Authors: Hashash Youssef M. A. , Fu Qingwei , Butkovich Jeremy 
Published: September 2004

AbstractAdvanced material constitutive models are used to describe complex soil behaviour. These models are often used in the solution of boundary value problems under general loading conditions. Users and developers of constitutive models need to methodically investigate the represented soil response under a wide range of loading conditions. This paper presents a systematic procedure for probing constitutive models. A general incremental strain probe, 6D hyperspherical strain probe (HSP), is introduced to examine rate‐independent model response under all possible strain loading conditions. Two special cases of HSP, the true triaxial strain probe (TTSP) and the plane‐strain strain probe (PSSP), are used to generate 3‐D objects that represent model stress response to probing. The TTSP, PSSP and general HSP procedures are demonstrated using elasto‐plastic models. The objects resulting from the probing procedure readily highlight important model characteristics including anisotropy, yielding, hardening, softening and failure. The PSSP procedure is applied to a Neural Network (NN) based constitutive model. It shows that this probing is especially useful in understanding NN constitutive models, which do not contain explicit functions for yield surface, hardening, or anisotropy. Copyright © 2004 John Wiley & Sons, Ltd.
Current Awareness in NMR in Biomedicine
Authors:   John Wiley & Sons, Ltd.
Published: September 2004

AbstractIn order to keep subscribers up‐to‐date with the latest developments in their field, John Wiley & Sons are providing a current awareness service in each issue of the journal. The bibliography contains newly published material in the field of NMR in biomedicine. Each bibliography is divided into 9 sections: 1 Books, Reviews ' Symposia; 2 General; 3 Technology; 4 Brain and Nerves; 5 Neuropathology; 6 Cancer; 7 Cardiac, Vascular and Respiratory Systems; 8 Liver, Kidney and Other Organs; 9 Muscle and Orthopaedic. Within each section, articles are listed in alphabetical order with respect to author. If, in the preceding period, no publications are located relevant to any one of these headings, that section will be omitted.
Quantification of water diffusion and relaxation times of human U87 tumors in a mouse model
Authors: Sun Yanping , Mulkern Robert V. , Schmidt Karl , Doshi Sameer , Albert Mitchell S. , Schmidt Nils O. , Ziu Mateo , Black Peter , Carrol Rona , Kieran Mark W. 
Published: September 2004

AbstractAssessing the potential of anti‐cancer agents can be greatly facilitated by applying MRI methods to investigations with animal models. Quantitative diffusion imaging, T1, and T2 measurements may offer valuable information for understanding properties of the tumor and for evaluating new therapeutic approaches. The human U87 high‐grade glial tumor is widely used for cancer investigations in orthotopic murine models. The physiological features of this model at the cellular and sub‐cellular level have not, however, been well characterized by MRI. In this study, we measured the diffusion, T1 and T2 characteristics of water in the human U87 tumor at 8.5 T in an orthotopic murine model in vivo and analyzed their detailed changes in the transition from the tumor core through the tumor periphery, and out to surrounding tissue using custom developed radial profile analysis software. For the tumor bearing mice (n = 10), the mean average apparent diffusion coefficient (ADC) of the tumor core was 1.03 ± 0.02 ( × 10−3 mm2/s), while in the contralateral normal brain it was 0.73 ± 0.03 ( × 10−3 mm2/s). The mean T1 in tumor was 2.03 ± 0.08 s and in normal brain tissue was 1.64 ± 0.06 s. The mean T2 in tumor was 0.062 ± 0.002 s and in normal brain tissue was 0.048 ± 0.001 s. The mean ADC, T1 and T2 of the tumor compared to normal tissue were significantly different (p < 0.005). Copyright © 2004 John Wiley & Sons, Ltd.
Amyotrophic lateral sclerosis: diffusion tensor tractography and voxel‐based analysis
Authors: Abe Osamu , Yamada Haruyasu , Masutani Yoshitaka , Aoki Shigeki , Kunimatsu Akira , Yamasue Hidenori , Fukuda Rinmei , Kasai Kiyoto , Hayashi Naoto , Masumoto Tomohiko , Mori Harushi , Soma Tsutomu , Ohtomo Kuni 
Published: September 2004

AbstractThe purpose of this study is to investigate whether the diffusional anisotropy of water molecules is disrupted in the pyramidal and extra‐pyramidal regions in patients with amyotrophic lateral sclerosis (ALS). We studied seven patients with probable ALS (four women, mean age ± SD, 57.3 ± 6.2 years old) according to the criteria of the World Federation of Neurology. A control group consisted of 11 age‐ and sex‐matched volunteers (six women, 57.1 ± 4.5) without disorders affecting the central nervous system. Voxel‐based diffusion tensor analysis was made with statistical parametric mapping (SPM99). We also created the normalized corticospinal tractography from the diffusion tensor data. The significant fractional anisotropy (FA) decrease in the ALS group was found in the right frontal subgyral white matter and left frontal precentral white matter. These clusters with significant FA decrease corresponded well to the average group map of the corticospinal tract in a standard reference frame. These results suggested that the combination of voxel‐based diffusion tensor analysis and diffusion tensor tractography might help determine the location of the affected neuronal tissues among ALS patients in a non‐invasive manner. Copyright © 2004 John Wiley & Sons, Ltd.
Methodological standardization for a multi‐institutional in vivo trial of localized 31P MR spectroscopy in human cancer research. In vitro and normal volunteer studies
Authors: Arias‐Mendoza F. , Zakian K. , Schwartz A. , Howe F. A. , Koutcher J. A. , Leach M. O. , Griffiths J. R. , Heerschap A. , Glickson J. D. , Nelson S. J. , Evelhoch J. L. , Charles H. C. , Brown T. R. ,   The Cooperative Group on MRS Applications in Cancer
Published: September 2004

AbstractA multi‐institutional group has been created to demonstrate the utility of in vivo 31P magnetic resonance spectroscopy (31P‐MRS) to study human cancers in vivo. This review is concerned with the novel problems concerning quality control in this large multinational trial of 31P MRS. Our results show that the careful and systematic performance of the quality control tests depicted here (standardized dual 1H/31P tuned radiofrequency probe, quality control procedures, routine use of 1H irradiation while acquiring 31P MR signals) has ensured comparable results between the different institutions. In studies made in vitro, the root‐mean‐square error was 3.6 %, and in muscle of healthy volunteers in vivo the coefficients of variance for the ratios phosphocreatine/nucleotide‐triphosphates, phosphocreatine/noise and nucleotide‐triphosphate/noise were 12.2, 7.0 and 10.8 %, respectively. The standardization of the acquisition protocol for in vivo‐localized 31P MR spectroscopy across the different institutions has resulted in comparable in vivo data, decreasing the possible problems related to a research study carried out under a multi‐institutional setting. Copyright © 2004 John Wiley & Sons, Ltd.
Numerical solution of second‐order, two‐point boundary value problems using continuous genetic algorithms
Authors: Abo‐Hammour Z. S. , Yusuf M. , Mirza N. M. , Mirza S. M. , Arif M. , Khurshid J. 
Published: September 2004

AbstractSecond‐order, two‐point boundary‐value problems are encountered in many engineering applications including the study of beam deflections, heat flow, and various dynamic systems. Two classical numerical techniques are widely used in the engineering community for the solution of such problems; the shooting method and finite difference method. These methods are suited for linear problems. However, when solving the non‐linear problems, these methods require some major modifications that include the use of some root‐finding technique. Furthermore, they require the use of other basic numerical techniques in order to obtain the solution. In this paper, the author introduces a novel method based on continuous genetic algorithms for numerically approximating a solution to this problem. The new method has the following characteristics; first, it does not require any modification while switching from the linear to the non‐linear case; as a result, it is of versatile nature. Second, this approach does not resort to more advanced mathematical tools and is thus easily accepted in the engineering application field. Third, the proposed methodology has an implicit parallel nature which points to its implementation on parallel machines. However, being a variant of the finite difference scheme with truncation error of the order O(h2), the method provides solutions with moderate accuracy. Numerical examples presented in the paper illustrate the applicability and generality of the proposed method. Copyright © 2004 John Wiley & Sons, Ltd.
Modified Newmark family for non‐linear dynamic analysis
Authors: Bui Q. V. 
Published: September 2004

AbstractA simple modification of the Newmark scheme is suggested, which keeps the total energy of mechanical systems constant and thereby enhances the unconditional stability in non‐linear dynamic analysis. Numerical damping, which is formulated on an energy basis, is also introduced and the dissipative character of the algorithm is guaranteed in the non‐linear regime. Representative examples in support of such a modified Newmark family are presented. Copyright © 2004 John Wiley & Sons, Ltd.
Gate elements at injection locations in numerical simulations of flow through porous media: applications to mold filling
Authors: Simacek Pavel , Advani Suresh G. 
Published: September 2004

AbstractMold filling in polymer and composite processing is usually modelled as a special case of Darcy flow in porous media. The flow pattern and the time necessary to fill the mold depend on the ‘gate’ locations where resin is injected into the closed mold. In composite manufacturing, these are commonly outlets of small tubes transporting resin from a reservoir and their diameters are several orders of magnitude smaller than the mold dimensions. Similar size issue is also encountered in other applications of flow through porous media, such as oil and water pumping and drilling. Traditionally, these inlets are modelled by pressure or flow rate boundary condition as applied at a node of the finite element mesh that represents the injection gate. The omission of the inlet radius in the model results in a mathematical singularity as the mesh gets refined. The computed pressure or flow field depends on the mesh size and does not converge to the accurate solution, as the finite element mesh is refined.It is possible to deal with this phenomenon by modelling the inlet geometry more accurately but this approach is inefficient, as it requires additional degrees of freedom and, above all, significantly complicates the modelling process if the inlet location is not fixed a priori.This paper presents a more efficient alternate solution. It uses special ‘gate’ elements embedded in the mesh around the injection locations. Instead of adjusting the geometrical modelling of the injection location, the adjacent elements use modified shape functions to accurately model pressure field in the neighbourhood of small radial inlet. The proper pressure field shape‐functions for ‘gate’ elements based on linear finite elements are derived. The implementation in an existing mold filling simulation and how the ‘gate elements’ are automatically selected is described. An example to demonstrate the use of ‘gate’ elements and convergence towards the accurate solution with mesh refinement is presented. Copyright © 2004 John Wiley & Sons, Ltd.
Hybrid‐stress six‐node prismatic elements
Authors: Sze K. Y. , Liu X. H. , Lo S. H. 
Published: September 2004

AbstractThis paper presents three novel hybrid‐stress six‐node prismatic elements. Starting from the element displacement interpolation, the equilibrating non‐constant stress modes for the first element are identified and orthogonalized with respect to the constant stress modes for higher computational efficiency. For the second element, the non‐constant stress modes are non‐equilibrating and chosen for the sake of stabilizing the reduced‐integrated element. The first two elements are intended for three‐dimensional continuum analysis with both passing the patch test for three‐dimensional continuum elements. The third element is primarily intended for plate/shell analysis. Shear locking is alleviated by a new assumed strain scheme which preserves the element accuracy with respect to the twisting load. Furthermore, the Poisson's locking along the in‐plane and out‐of‐plane directions is overcome by using the hybrid‐stress modes of the first element. The third element passes the patch test for plate/shell elements. Unless the element assumes the right prismatic geometry, it fails the patch test for three‐dimensional continuum elements. It will be seen that all the proposed elements are markedly more accurate than the conventional fully integrated element. Copyright © 2004 John Wiley & Sons, Ltd.
Articulated mechanism design with a degree of freedom constraint
Authors: Kawamoto A. , Bendsøe M. P. , Sigmund O. 
Published: September 2004

AbstractThis paper deals with design of articulated mechanism using a truss‐based ground‐structure representation. The proposed method can accommodate extremely large displacement by considering geometric non‐linearity. In addition, it can also control the mechanical degrees of freedom (DOF) of the resultant mechanism by using a DOF equation based on Maxwell's rule. The optimization is based on a relaxed formulation of an original integer problem and also involves developments directed at handling the redundancy inherent in the ground‐structure representation. One planar test example is selected as the basis for the developments so as to compare the proposed method with other alternative approaches including a graph‐theoretical enumeration approach which guarantees the identification of the globally optimal solution. Also, an inverter problem is treated where a continuation method is required in order to direct the optimization algorithm towards an integer solution. Copyright © 2004 John Wiley & Sons, Ltd.
Four‐node incompatible plane and axisymmetric elements with quadratic completeness in the physical space
Authors: Huang Y. Q. , Li Q. S. 
Published: September 2004

AbstractIn this paper, four‐node incompatible elements with quadratic completeness in the physical space are developed for plane and axisymmetric problems. Various revision techniques of the incompatible strain matrix or shape function are proposed to guarantee the incompatible elements to pass the constant stress patch test. In contrast with other elements in the same level, the present one gives reasonable stress solutions without any stress recovery such as the bilinear extrapolation and least square approximation. Numerical examples are given to investigate the accuracy, sensitivity to mesh distortion and locking in the incompressible calculation of the present method when irregular coarse meshes are used. Copyright © 2004 John Wiley & Sons, Ltd.
Optimization of support positions to maximize the fundamental frequency of structures
Authors: Wang D. , Jiang J. S. , Zhang W. H. 
Published: September 2004

AbstractIn this paper, the position optimization of simple supports is implemented to maximize the fundamental frequency of a beam or plate structure. Both elastic and rigid supports are taken into account. First, the frequency sensitivity with respect to the movement of a simple support is derived using the discrete method. By means of the shape functions of the finite element method, closed‐form sensitivity formulations are developed straightforwardly. Then, a heuristic approach, called evolutionary shift method, is presented for optimizing support positions with a fixed grid mesh scheme. Based on the design sensitivity analysis, the support with the highest efficiency is shifted in priority along the elementary edges with the interval (step) of the elementary size. To facilitate the convergence of the process, the interpolation technique is employed to evaluate the solution more accurately. Finally, three numerical examples are presented to demonstrate the validity of the sensitivity analysis and the effectiveness of the optimization method. Copyright © 2004 John Wiley & Sons, Ltd.
An efficient method for decomposition of regular structures using graph products
Authors: Kaveh A. , Rahami H. 
Published: September 2004

AbstractIn this paper an efficient method is presented for calculating the eigenvalues of regular structural models. A structural model is calledregularif they can be viewed as the direct or strong Cartesian product of some simple graphs known as theirgenerators. The eigenvalues of the adjacency and Laplacian matrices for a regular graph model are easily obtained by the evaluation of eigenvalues of its generators. The second eigenvalue of the Laplacian of a graph is also obtained using a much faster and much simple approach than the existing methods. Copyright © 2004 John Wiley & Sons, Ltd.
‘How we think they think’: thought styles in the management of international aid
Authors: Curtis Donald 
Published: September 2004

AbstractAid administration is characterised by high moral objectives and often frustratingly low achievements. This article explores the idea that the problem lies not in inadequate policy or instruments as such but in the thinking processes that emerge within policy circles, at delivery levels within aid administration and at the interface between donor and recipient, to which the trade likes to apply the notion of ‘partnership’. Cultural Theory identifies three distinct and often contradictory ways of thinking that reflect individualist, group and hierarchical value premises. It is adopted here to explore how these types of thinking apply within aid administration, finding that the policy process is a surprisingly ‘groupie’ kind of activity, emphasising the sharing of values and understandings within donor circles. Delivery agents (donor field offices) by contrast are under hierarchical pressure to turn the outcomes into packaged deliverables, whether the ‘good’ is packageable or not. Supported by NPM orthodoxies, these agents seek control through linear programming and performance monitoring. A third contradiction is revealed when the donor attempts to bring such packages into a partnership relationship with recipient governments. Partnership is about sharing and dealing. But what the recipient is offered is a package with Henry Ford type characteristics: ‘any colour you like (social aspiration), as long as it is black (PRSP formula)’. The article is biased; from the perspective of a consultant caught in the middle; but if there is truth in the findings it might just open the door to new styles of aid relationship and novel delivery vehicles. Copyright © 2004 John Wiley & Sons, Ltd.
Structural and solvent effects on rates of solvolysis of secondary alkyl substrates—an update
Authors: Bentley T. William , Roberts Ian 
Published: September 2004

AbstractRate constants for solvolyses of secondary alkyl tosylates in fluorinated media [including hexafluoropropan‐2‐ol (HFIP), hexafluoroacetone sesquihydrate, and trichloromethylbis(trifluoromethyl)carbinol] are reported. Rates of solvolysis of 2‐adamantyl p‐toluenesulfonate in 97% (w/w) HFIP–water at 25°C are neither retarded by the addition of NaOTs nor accelerated greatly by NaClO4. The α‐deuterium kinetic isotope effect for solvolyses of 1‐(1‐adamantyl)ethyl methanesulfonate in 20% acetone–water at 25°C is 1.14. Mechanistic implications of these results are discussed. Copyright © 2004 John Wiley & Sons, Ltd.
Ionic liquids: solvent properties and organic reactivity
Authors: Chiappe Cinzia , Pieraccini Daniela 
Published: September 2004

AbstractIonic liquids are a fascinating class of novel solvents, which are attracting attention as possible ‘green’ alternative to volatile molecular organic solvents to be applied in catalytic and organic reactions and electrochemical and separation processes. Over 200 room temperature ionic liquids are known but for most of them physico‐chemical data are incomplete or lacking. Furthermore, despite the incredible number of potential ionic liquids (evaluated as  > 1014), generally only a few imidazolium‐based salts are used in synthesis. Moreover, most of the data reported to date were focused on the effect that these new solvents have on chemical reaction products; only a few reports evidence the effect on reaction mechanisms or rate or equilibrium constants. In this review, the physico‐chemical properties of the most used ionic liquids, that are relevant to synthesis, are discussed and a decided emphasis is placed on those properties that most clearly illuminate the ability of ionic liquids to affect the mechanistic aspects of some organic reactions. Copyright © 2004 John Wiley & Sons, Ltd.
Synthesis of poly(L‐lactide)‐grafted pullulan through coupling reaction between amino group end‐capped poly(L‐lactide) and carboxymethyl pullulan and its aggregation behavior in water
Authors: Ouchi Tatsuro , Minari Tetsuji , Ohya Yuichi 
Published: September 2004

AbstractPoly(L‐lactide) (PLLA) with terminal primary amino groups (PLLA‐NH2) was synthesized and used to construct PLLA‐grafted pullulan (Pul‐g‐PLLA). It consisted of a hydrophilic carboxymethyl Pul (CM‐Pul) main chain and hydrophobic PLLA graft chains that were created through a direct coupling reaction between PLLA‐NH2 and CM‐Pul using 2‐ethoxy‐1‐(ethoxycarbonyl)‐1,2‐dihydroquinoline as a condensation reagent. Pul‐g‐PLLAs with over 78 wt % sugar unit content were found to form nanometer‐sized aggregates in water. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5482–5487, 2004
Unexpected end‐groups of poly(acrylic acid) prepared by RAFT polymerization
Authors: Llauro Marie‐France , Loiseau Julien , Boisson Fernande , Delolme Frédéric , Ladavière Catherine , Claverie J. 
Published: September 2004

AbstractLow‐molecular‐weight poly(acrylic acid) (PAA) was synthesized by reversible addition fragmentation chain transfer polymerization with a trithiocarbonate as chain‐transfer agent (CTA). With a combination of NMR spectroscopy and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry, the PAA end‐groups of the polymer were analyzed before and after neutralization by sodium hydroxide. The polymer prior to neutralization is made up of the expected trithiocarbonate chain‐ends and of the H‐terminated chains issued from a reaction of transfer to solvent. After neutralization, the trithiocarbonates are transformed into thiols, disulfides, thiolactones, and additional H‐terminated chains. By quantifying the different end‐groups, it was possible to demonstrate that fragmentation is the rate limiting step in the transfer reaction. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5439–5462, 2004