bluuebunny/crossref_metadata_2025_split huggingface dataset:
Extension theorems for Stokes and Lamé equations for nearly incompressible media and their applications to numerical solution of problems with highly discontinuous coefficients
Authors: Bakhvalov N. S. , Knyazev A. V. , Parashkevov R. R. 
Published: September 2002

AbstractWe prove extension theorems in the norms described by Stokes and Lamé operators for the three‐dimensional case with periodic boundary conditions. For the Lamé equations, we show that the extension theorem holds for nearly incompressible media, but may fail in the opposite limit, i.e. for case of absolutely compressible media. We study carefully the latter case and associate it with the Cosserat problem.Extension theorems serve as an important tool in many applications, e.g. in domain decomposition and fictitious domain methods, and in analysis of finite element methods. We consider an application of established extension theorems to an efficient iterative solution technique for the isotropic linear elasticity equations for nearly incompressible media and for the Stokes equations with highly discontinuous coefficients. The iterative method involves a special choice for an initial guess and a preconditioner based on solving a constant coefficient problem. Such preconditioner allows the use of well‐known fast algorithms for preconditioning.Under some natural assumptions on smoothness and topological properties of subdomains with small coefficients, we prove convergence of the simplest Richardson method uniform in the jump of coefficients. For the Lamé equations, the convergence is also uniform in the incompressible limit.Our preliminary numerical results for two‐dimensional diffusion problems show fast convergence uniform in the jump and in the mesh size parameter. Copyright © 2002 John Wiley & Sons, Ltd.
A method for representing boundaries in discrete element modelling—part I: Geometry and contact detection
Authors: Kremmer M. , Favier J. F. 
Published: September 2002

AbstractThe discrete element method for analysis of the dynamic behaviour of discontinuous media is well established. However, its application to engineering problems is still limited to simplified representations of structural boundaries and their kinematics. In this paper a method is developed for representing three‐dimensional boundaries of arbitrary geometry and for modelling the interaction between boundary objects and particles within the discrete element modelling framework. The approach, which we term the finite wall method, uses planar triangular elements to approximate the boundary surface topology. Any number of wall elements can be used to model the shape of the structure. A contact detection scheme is presented for boundary surfaces and spheres based on a series of vector projections to reduce the problem dimensionally. The algorithm employs spatial sporting to obtain the set of potential contacts between spheres and wall elements prior to contact resolution. In a further stage, all possible contact conditions including contact with surfaces, edges and corners are explicitly determined. Part I of this two‐part series of papers describes the finite wall method for representation of surface geometry and fully elaborates the method for detecting and resolving contact between boundary wall elements and spheres. In Part II the finite wall method is extended to apply kinematics to linearly independent boundary objects using combinations of translational and rotational motion. An approach is developed for coupling the DEM with the FEM for the purpose of optimising the design of structures which are dynamically interacting with particulate media. Copyright © 2001 John Wiley & Sons, Ltd.
Theory and numerics of a thermodynamically consistent framework for geometrically linear gradient plasticity
Authors: Liebe Tina , Steinmann Paul 
Published: September 2002

AbstractThe paper presents the theory and the numerics of a thermodynamically consistent formulation of gradient plasticity at small strains. Starting from the classical local continuum formulation, which fails to produce physically meaningful and numerically converging results within localization computations, a thermodynamically motivated gradient plasticity formulation is envisioned. The model is based on an assumption for the Helmholtz free energy incorporating the gradient of the internal history variable, a yield condition and the postulate of maximum dissipation resulting in an associated structure. As a result the driving force conjugated to the hardening evolution is identified as the quasi‐non‐local drag stress which incorporates besides the strictly local drag stress essentially the divergence of a vectorial hardening flux. At the numerical side, besides the balance of linear momentum, the algorithmic consistency condition has to be solved in weak form. Thereby, the crucial issue is the determination of the active constraints exhibiting plastic loading which is solved by an active set search algorithm borrowed from convex non‐linear programming. Moreover, different discretization techniques are proposed in order to compare the FE‐performance in local plasticity with the advocated gradient formulation both for hardening and softening. Copyright © 2001 John Wiley & Sons, Ltd.
Smooth C1‐interpolations for two‐dimensional frictional contact problems
Authors: Wriggers P. , Krstulovic‐Opara L. , Korelc J. 
Published: September 2002

AbstractFinite deformation contact problems are associated with large sliding in the contact area. Thus, in the discrete problem a slave node can slide over several master segments. Standard contact formulations of surfaces discretized by low order finite elements leads to sudden changes in the surface normal field. This can cause loss of convergence properties in the solution procedure and furthermore may initiate jumps in the velocity field in dynamic solutions. Furthermore non‐smooth contact discretizations can lead to incorrect results in special cases where a good approximation of the contacting surfaces is needed. In this paper a smooth contact discretization is developed which circumvents most of the aformentioned problems. A smooth deformed surface with no slope discontinuities between segments is obtained by a C1‐continuous interpolation of the master surface. Different forms of discretizations are possible. Among these are Bézier, Hermitian or other types of spline interpolations. In this paper we compare two formulations which can be used to obtain smooth normal and tangent fields for frictional contact of deformable bodies. The formulation is developed for two‐dimensional applications and includes finite deformation behaviour. Examples show the performance of the new discretization technique for contact. Copyright © 2001 John Wiley & Sons, Ltd.
Advances in computational design and optimization with application to MEMS
Authors: Chen Bing‐Chung , Silva Emílio C. N. , Kikuchi Noboru 
Published: September 2002

AbstractIn this paper, we will highlight the current research which employs the topology optimization to find the optimal configuration of various smart structures and microstructures, specifically, pressure actuated compliant mechanisms, flextensional transducers, and porous material microstructures with unusual thermoelastic properties. These examples demonstrate that the topology optimization problem involving multiple physics domain is a viable direction for future research, in particular, for sensor and actuator design. Copyright © 2001 John Wiley & Sons, Ltd.
Nursing intervention studies: A descriptive analysis of issues important to clinicians
Authors: Brown Sarah Jo 
Published: September 2002

AbstractWhen reading a report of an intervention study, clinicians are interested in knowing: whether the intervention is effective, with whom it is effective, how much benefit it produces, and whether associated, adverse outcomes occur. Recommendations have been made in the research literature regarding how to conduct and report intervention studies so as to produce knowledge regarding these questions. This descriptive study was conducted to estimate the frequency with which these recommendations are being used in nursing intervention studies. Data pertinent to five research questions were extracted from 84 experimental and quasi‐experimental study reports published between 1998 and 2000. Seventeen percent of the studies used a design that could statistically test for variation in intervention effect depending on the level of an individual characteristic. However, a test of interaction was actually conducted in only 8% of the studies. The magnitude of the intervention's effect was addressed in 38% of the study reports. Providing the proportion of persons in the intervention group who attained a discrete outcome was the most frequently used way of showing intervention magnitude. Associated, adverse outcomes were examined in 23% of the studies, and were most often measured as continuous variables. The low level of use of recommended methods leads the author to suggest dialogue between clinicians and researchers to determine if intervention studies are being conducted and reported in ways that produce knowledge that is useful to clinicians. © 2002 Wiley Periodicals, Inc. Res Nurs Health 25:317–327, 2002
Wives giving care to husbands with alzheimer's disease: A process of interpretive caring
Authors: Perry JoAnn 
Published: September 2002

AbstractWives giving care to spouses with dementia are a particularly vulnerable segment of the caregiving population. In this article a grounded theory study of 20 such wives is described, with their experiences explained as a process of interpretive caring. Wives began the process by either seeing changes in their husbands or recognizing changes in their work. Following this, the wives moved on to a phase of drawing inferences about what they observed and then took over their husbands' roles and responsibilities. These changes prompted the wives to rewrite identities for their husbands that incorporated the dementia and to rewrite identities for themselves to reflect their new roles, abilities, and strengths. Finally, the wives set about constructing a new daily life to sustain both partners. This process is neutral and allows for positive aspects of caring to be considered along with grief and frustration. © 2002 Wiley Periodicals, Inc. Res Nurs Health 25:307–316, 2002
Cultural differences in responses to a likert scale
Authors: Lee Jerry W. , Jones Patricia S. , Mineyama Yoshimitsu , Zhang Xinwei Esther 
Published: September 2002

AbstractCultural differences in responses to a Likert scale were examined. Self‐identified Chinese, Japanese, and Americans (N=136, 323, and 160, respectively) recruited at ethnic or general supermarkets in Southern California completed a 13‐question Sense of Coherence scale with a choice of either four, five, or seven responses in either Chinese, Japanese, or English. The Japanese respondents more frequently reported difficulty with the scale, the Chinese more frequently skipped questions, and both these groups selected the midpoint more frequently on items that involved admitting to a positive emotion than did the Americans, who were more likely to indicate a positive emotion. Construct validity of the scale tended to be better for the Chinese and the Americans when there were four response choices and for the Japanese when there were seven. Although culture affected response patterns, the association of sense of coherence and health was positive in all three cultural groups. © 2002 Wiley Periodicals, Inc. Res Nurs Health 25:295–306, 2002
An analysis of the relationship between job satisfaction and job stress in correctional nurses
Authors: Flanagan Nancy A. , Flanagan Timothy J. 
Published: September 2002

AbstractStamps and Piedmonte's Index of Work Satisfaction and Harris's Nurse Stress Index were completed by 287 registered nurses employed in state prison health care facilities in order to assess job satisfaction and job stress among correctional nurses. Correctional nurses' expectations about job satisfaction were influenced by pay and autonomy. This finding was consistent with studies of hospital nurses. Important sources of job satisfaction were professional status and interaction with employees. Analysis of differences between expectations and sources of job satisfaction may provide understanding of career benefits and sources of dissatisfaction. Time pressures and organizational support and involvement were sources of stress. Multivariate analyses showed an inverse relationship between stress and job satisfaction. Information about job satisfaction and work stress and their correlates may be used to develop strategies to improve the recruitment and retention of correctional nurses. © 2002 Wiley Periodicals, Inc. Res Nurs Health 25:282–294, 2002
A one‐pot, two‐step reaction for the synthesis of VLC acidic polymers for resin modified glass‐ionomers
Authors: Schricker S. R. , Dotrong M. H. , Huang Y. , Culbertson B. M. 
Published: September 2002

AbstractMethacrylate‐functionalized aromatic oxazolines are evaluated for attaching pendant methacrylate groups to acid containing polymers. Typically, these reactions use the toxic liquid 2‐isocyanatoethyl methacrylate (IEM) to functionalized the acid containing polymer. Methacrylate‐functionalized oxazolines will add to acid containing polymer in aqueous solvent. Thus, in a one‐pot, two‐step reaction the acid containing polymer can be synthesized and then reacted with the methacrylate‐functionalized oxazoline. The visible light‐curable (VLC) polymer can then be formulated in resin modified glass‐ionomers. The resulting glass‐ionomers have properties that are comparable to commercial materials. Copyright © 2001 John Wiley & Sons, Ltd.
Photooxidations of phenol, cyclopentadiene and citronellol with photosensitizers ionically bound at a polymeric ion exchanger
Authors: Gerdes Robert , Bartels Oliver , Schneider Gerhard , Wöhrle Dieter , Schulz‐Ekloff Günter 
Published: September 2002

AbstractDifferent metal tetrasulfophthalocyanines and rose bengal were employed as photosensitizers in the photooxidation of phenol, cyclopentadiene and (S)‐(−)‐citronellol. Ionically polymer bound photosensitizers were easily obtained by the reaction of negatively charged low‐molecular‐weight phthalocyanines with the strong basic anion exchanger Amberlite® IRA 400. The activities of the low‐molecular‐weight and the polymer systems are compared. Especially immobilized phthalocyanines which exhibit the advantages of good activity, as well as stability against photobleaching, and can be used repeatedly. Copyright © 2001 John Wiley & Sons, Ltd.
Blends of functionalized terthiophenes with polyethylene as materials for new linear polarizers
Authors: Ciardelli Francesco , Cellai Caterina , Pucci Andrea , Regoli Leonardo , Ruggeri Giacomo , Tirelli Nicola , Cardelli Camillo 
Published: September 2002

AbstractThe dispersibility of terthiophene alkyl derivatives in polyethylene films was comparatively investigated by calorimetry, differential scanning calorimetry (DSC) and microscopy. Polyethylene affinity of the terthiophenes increases with increasing linear alkyl chain length, but the increased tendency to separate crystallization gives rise to distinct phases and dishomogeneity. Drawing of the film at higher temperature than chromophore and poly(ethylene)(PE) melting points (141 °C) improves dispersibility with parallel orientation of chromophore molecules and PE macromolecules. These phenomena are important in determining the high dichroism of new polymeric host–guest polarizers based on blends of ultra‐high‐molecular‐weight poly(ethylene)(UHMWPE) with linear anisotropic molecules based on terthiophene nuclei functionalized with push‐pull and alkyl groups. The PE affinity of the chromophores favored by their alkyl chains is one of the key factors in allowing their dispersion in the oriented poly(ethylene) films which show good performances as linear optical polarizers. Copyright © 2001 John Wiley & Sons, Ltd.
Peripherally polymerized octacyanophthalocyanine as cathode material of lithium rechargeable batteries1
Authors: Asai Yoshihiro , Onishi Ken , Arai Takayuki , Matsumoto Michiko , Miyata Seizo , Shigehara Kiyotaka 
Published: September 2002

AbstractHighly pure metal‐free octacyanophthalocyanine (H2PcOC) was further converted into two‐dimensional polymers (PPcCN) by solid‐phase reaction in presence of tetracyanobenzene. PPcCN showed the electric conductivity as high as about 5·10−4 S cm−1, 2‐orders of magnitude larger than that of H2PcOC. Since PPcCN exhibited reversible multi‐electron redox reaction at relatively positive potential near −0.3 V vs. NHE and was insoluble throughout the redox reaction in any organic electrolyte solutions, this polymer is useful in lithium (ion) rechargeable batteries as cathode‐active material. When the depth of discharge was controlled to 150 mAh g−1, the cell composed of [metallic Li/electrolyte/PPcCN] gave very stable cycle property for several hundred charge‐discharge cycles with the average output voltage of 2.73 V and the energy density of 409 Wh kg−1, of which value is comparable to commercial lithium ion batteries based on Lix(CoO2)y cathode. Copyright © 2001 John Wiley & Sons, Ltd.
Branched epoxy copolymers with oligo(benzoate) side chains carrying donor and acceptor functions in each end1
Authors: Kimura Tatsumi , Fukuda Takashi , Matsuda Hiro , Komoriya Atsushi , Kazama Mariko , Kato Masao , Okada Shuji , Nakanishi Hachiro 
Published: September 2002

AbstractWe synthesized branched epoxy copolymers with oligo‐(benzoate) to create unique second‐order nonlinear optical (NLO) active polymers (PEA3‐C3, PEA3‐C3F6 and PEA3‐K) on the basis of new architecture. The cutoff wavelength (λ∞) of these polymers was satisfactory shorter than the visible region, i.e., λ∞ = ca. 400 nm. Second‐order NLO properties for poled polymer films of thus synthesized were investigated. These polymer films after poling treatment exhibited good transparency in visible region and the second‐order nonlinear optical coefficient, d33, of 7∼10 pmV−1. Copyright © 2001 John Wiley & Sons, Ltd.
Synergism and catalysis in flame retardancy of polymers
Authors: Lewin Menachem 
Published: September 2002

AbstractSynergististic and catalytic effects in flame retardancy technology are reviewed. An attempt is reported to define and determine the synergistic effectivity (SE) and the catalytic effectivity (CAT‐EFF) of a number of systems operating according to the accepted mechanism. Synergistic effects in the halogen based gas phase systems involving Br/Sb
2O
3, Cl/Sb
2O
3, Br/NH
3, Br/Cl, Br/P, and of the condensed phase based intumescent systems— ammonium polyphosphate/pentaerythritol/N derivatives are discussed and compared. Recently discovered catalysis of intumescent systems by divalent and transition metal compounds involving a maximum effect catalyst concentration is discussed in the light of thermoanalytical data. Recent work on catalysis of endothermic flame retardancy systems based on aluminum trihydrate and magnesium hydroxide are also reviewed. Copyright­© 2001 John Wiley & Sons, Ltd.
Synthesis of CuII‐complexed polymers and use as catalysts in the hydrolytic decontamination of Sarin nerve agent†
Authors: Blacker N. C. , Findlay P. H. , Sherrington D. C. 
Published: September 2002

AbstractA range of polymer‐supported bidentate amine Cu
II complexes have been synthesized based on linear polymers, crosslinked resins and hydrogels as precursor species. Linear styrene, acrylate and methacrylate structures have been examined along with reactive crosslinked resins derived from vinylbenzyl chloride, glycidyl methacrylate and methacrylic acid (Amberlite IRC‐50). Hydrogels based on hydroxyethyl methacrylate, hydroxyethyl acrylate and hydroxypropyl acrylate, each copolymerized with a diamine containing monomer, have also been prepared.Each Cu
II‐complexed polymer has been assessed as a catalyst in the hydrolytic decomposition of the nerve agent, Sarin, as a possible strategy for developing self‐decontaminating materials and coatings for both personnel and equipment in the event of a nerve agent challenge in the field.Based on the measured half‐lives for hydrolysis of Sarin all of the polymer Cu
II complexes show remarkable catalytic activity relative to the rate of the uncatalyzed hydrolysis reaction. The linear polymethacrylate‐based catalysts are the most active followed by the linear polystyrene‐based species, the macroporous polymethacrylates and the polystyrene resins. The polymethacrylate hydrogels are the least effective. It seems therefore that the hydrophilic/hydrophobic balance is important in controlling Sarin access to the catalytic sites, and this seems to be optimal in the linear polymethacrylate‐based catalysts. The results are discussed further in the context of the existing literature. Copyright © 2001 John Wiley & Sons, Ltd.
Metal complexes with linear and crosslinked polysaccharides as mediators of angiogenesis
Authors: Barbucci R , Lamponi S , Magnani A , Peluso G , Petillo O 
Published: September 2002

AbstractBioactive macromolecules resulting from chemical modification of hyaluronic acid (Hyal) have been designed to improve the compatibility of biomaterials used for cardiovascular prostheses. Hyal has been sulphated to obtain derivatives (HyalS) with a number of sulphate groups ranging from 1 to 4 per disaccharide unit. Hydrogels of Hyal have been obtained by cross‐linking the free polysaccharide. An appropriate Hyal/cross‐linking agent ratio has produced a hydrogel with a degree of crosslinking of 50%.In the present study, the ability to stimulate endothelial cell adhesion and migration was evaluated for free Hyal, HyalS3.5 and their complexes with Cu(II) and Zn(II) ions. The results revealed that Hyal and [Cu(OH)2HyalS3.5](4.5)− induced cell adhesion, while [ZnHyalS3.5](2.5)− and [Zn(OH)2HyalS3.5](4.5)− inhibited the process. The chemotactic activity of increasing concentrations of the above complexes was also evaluated, demonstrating that [Cu(OH)2HyalS3.5](4.5)− complex at 1 µM concentration was the most active in inducing cell migration. These results were also confirmed by analysing cell migration in agarose. The 50% hydrogel bound Cu(II) and Zn(II) and the in vivo biocompatibility of the complexes was found to be good. Copyright © 2001 John Wiley & Sons, Ltd.
Atomic force microscopy study of the polymer growth in a polymer stabilized liquid crystal
Authors: Guillard H. , Sixou P. , Tottreau O. 
Published: September 2002

AbstractThe growth of a cholesteric polymer network in a polymer stabilized cholesteric texture (PSCT) was studied by atomic force microscopy (AFM). The liquid crystal is removed by dipping the samples into a solvent bath and the polymer network remaining on each strip is analyzed. Several aspects of the polymer growth were studied: irradiation time, use of an orientation layer and application of an electric field during polymerization. AFM has proved to be an accurate means to study polymer networks thanks to its high resolution. The pitch of the cholesteric polymer is observable under special conditions of polymerization. Copyright © 2002 John Wiley & Sons, Ltd.