bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phase Space Stability Error Control with Variable Time‐stepping Runge‐Kutta Methods for Dynamical Systems
Authors: Humphries Tony , Vigneswaran R. 
Published: December 2004

AbstractWe consider a phase space stability error control for numerical simulation of dynamical systems. We illustrate how variable time‐stepping algorithms perform poorly for long time computations which pass close to a fixed point. A new error control was introduced in [9], which is a generalization of the error control first proposed in [8]. In this error control, the local truncation error at each step is bounded by a fraction of the solution arc length over the corresponding time interval. We show how this error control can be thought of either a phase space or a stability error control. For linear systems with a stable hyperbolic fixed point, this error control gives a numerical solution which is forced to converge to the fixed point. In particular, we analyze the forward Euler method applied to the linear system whose coefficient matrix has real and negative eigenvalues. We also consider the dynamics in the neighborhood of saddle points. We introduce a step‐size selection scheme which allows this error control to be incorporated within the standard adaptive algorithm as an extra constraint at negligible extra computational cost. Theoretical and numerical results are presented to illustrate the behavior of this error control. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimal Control of Geodesics in Riemannian Manifolds
Authors: Rozsnyo Roland , Semmler Klaus‐Dieter 
Published: December 2004

AbstractIn this paper, we present a method based on an optimal control technique for numerical computations of geodesic paths between two fixed points of a Riemannian Manifold under the assumption of existence. In this method, the control variable is the tangent vector to the geodesic we are looking for. Defining a cost function corresponding to the requested control, we explain how to derive the optimal control algorithm by the use of an adjoint state method for the calculation of the gradient of that cost function. We then give a geometrical interpretation of the adjoint state. After having introduced the discrete optimal control algorithm, we show an application to wooden roof design. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Moment‐Based Method for Large‐Scale Generalized Eigenvalue Problems
Authors: Sakurai Tetsuya , Tadano Hiroto , Inadomi Yuichi , Nagashima Umpei 
Published: December 2004

AbstractIn this paper we consider a method for finding several eigenvalues and corresponding eigenvectors of large‐scale generalized eigenvalue problems. In this method, a small matrix pencil that has only the desired eigenvalues is derived using complex moments obtained via numerical integration. Since the process to derive the moments can be performed in parallel and we do not need to exchange data between processes, the presented method is suitable for master‐worker programming models. We have implemented and tested the proposed method in a grid RPC (remote procedure call) system. Numerical examples illustrate the properties of our approach. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Efficient Implementation of the Nelder–Mead Search Algorithm
Authors: Singer Saša , Singer Sanja 
Published: December 2004

AbstractThe Nelder–Mead or simplex search algorithm is one of the best known algorithms for unconstrained optimization of non–smooth functions. Even though the basic algorithm is quite simple, it is implemented in many different ways. Apart from some minor computational details, the main difference between various implementations lies in the selection of convergence (or termination) tests, which are used to break the iteration process. A fairly simple efficiency analysis of each iteration step reveals a potential computational bottleneck in the domain convergence test. To be efficient, such a test has to be sublinear in the number of vertices of the working simplex. We have tested some of the most common implementations of the Nelder–Mead algorithm, and none of them is efficient in this sense.Therefore, we propose a simple and efficient domain convergence test and discuss some of its properties. This test is based on tracking the volume of the working simplex throughout the iterations. Similar termination tests can also be applied in some other simplex–based direct search methods. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimal Ship Routing Based on Wind and Wave Forecasts
Authors: Vlachos D. S. 
Published: December 2004

AbstractShort term accurate wind and wave forecasts can be used for optimal ship routing. In this work, a method is presented for manipulating the POSEIDON [1] system forecasts for the Greek seas and for producing optimal routes for small and medium size ships. The method is composed from a geometrical calculation of all possible routes between two points and from an iterative algorithm which approximates the optimal (or an almost optimal) route. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modern Synthetic Methods for Fluorine‐Substituted Target Molecules
Authors: Shimizu Masaki , Hiyama Tamejiro 
Published: December 2004

AbstractFluorine has come to be recognized as a key element in materials science: in heat‐transfer agents, liquid crystals, dyes, surfactants, plastics, elastomers, membranes, and other materials. Furthermore, many fluorine‐containing biologically active agents are finding applications as pharmaceuticals and agrochemicals. Progress in synthetic fluorine chemistry has been critical to the development of these fields and has led to the invention of many novel fluorinated molecules as future drugs and materials. As a result of the electronic effects of fluorine substituents, fluorinated substrates and reagents often exhibit unusual and unique chemical properties, which often make them incompatible with established synthetic methods. Thus, the problem of how to control the unusual properties of compounds with fluorine substituents deserves much attention, so as to promote the design of facile, efficient, and environmentally benign methods for the synthesis of valuable organofluorine targets.
Polyol recovery from biomass‐based polyurethane foam by glycolysis
Authors: Lee Seung‐Hwan , Ohkita Tsutomu , Teramoto Yoshikuni 
Published: December 2004

AbstractBiomass‐based polyurethane foams (PUFs) were degraded by glycolysis and the polyols recovered were reused to prepare a rigid polyurethane foam. Biomass‐based PUFs were prepared from liquefied wood or starch polyols and grafted products with polycaprolactone. The glycolysis was conducted using diethylene glycol (DEG) as a solvent and potassium acetate as a catalyst under various reaction conditions. The effects of reaction conditions on the properties of the polyols recovered were examined. The average‐weight molecular weight (Mw) and viscosity decreased as the reaction time, temperature, and ratio of DEG/PUF increased, whereas the hydroxyl value increased. It was found from IR measurements that the conversion of the urethane functional group (NCOO) increased as the glycolysis proceeded. The PUF prepared from the recovered polyols had properties comparable to those of the raw PUF used in glycolysis. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 975–980, 2005
Melt index modeling with support vector machines, partial least squares, and artificial neural networks
Authors: Han In‐Su , Han Chonghun , Chung Chang‐Bock 
Published: December 2004

AbstractThis article presents the application of three black‐box modeling methods to two industrial polymerization processes to predict the melt index, which is considered an important quality variable determining product specifications. The modeling methods covered in this study are support vector machines (SVMs; known as state‐of‐the‐art modeling methods), partial least squares (PLS), and artificial neural networks (ANNs); the processes are styrene–acrylonitrile (SAN) and polypropylene (PP) polymerizations currently operated for commercial purposes in Korea. Brief outlines of the modeling procedure are presented for each method, followed by the procedures for training and validating the models. The SVM models yield the best prediction performances for both the SAN and PP polymerization processes. However, the ANN models fail to accurately predict the melt index when sufficient data are not available for model training in the PP polymerization process. The PLS models are not effective either when applied to the SAN polymerization process, for which the melt index has strong nonlinear functionality with the process variables. The good prediction performance that the SVM models show despite the insufficient data or strong process nonlinearity suggests that SVMs can be effectively used as alternative to PLS or ANNs for modeling the melt indices in other polymerization processes as well. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 967–974, 2005
Low molecular weight block copolymers as plasticizers for polystyrene
Authors: Hansen Kristoffer K. , Nielsen Charlotte Juel , Hvilsted Søren 
Published: December 2004

AbstractPolystyrene‐b‐alkyl, polystyrene‐b‐polybutadiene‐b‐polystyrene, and polystyrene‐b‐poly(propylene glycol)monotridecyl ether were synthesized using macro initiators and atom transfer radical polymerization or by esterifications of homopolymers. The aim was a maximum molecular weight of 4 kg/mol and minimum polystyrene content of 50 w/w %, which by us is predicted as the limits for solubility of polystyrene‐b‐alkyl in polystyrene. DSC showed polystyrene was plasticized, as seen by a reduction in glass transition temperature, by block copolymers consisting of a polystyrene block with molecular weight of approximately 1 kg/mol and an alkyl block with a molecular weight of approximately of 0.3 kg/mol. The efficiency of the block copolymers as plasticizers increases with decreasing molecular weight and polystyrene content. In addition, polystyrene‐b‐alkyl is found to be an efficient plasticizer also for polystyrene‐b‐polyisoprene‐b‐polystyrene (SIS) block copolymers. The end use properties of SIS plasticized with polystyrene‐b‐alkyl, measured as tensile strength, is higher than for SIS plasticized with dioctyl adipate. The polystyrene‐b‐polybutadiene‐b‐polystyrene and polystyrene‐b‐poly(propylene glycol)monotridecyl ether series were only partially soluble in polystyrene and insoluble in the polystyrene phase of SIS. For the lowest molecular weight samples, this leads to measurable plasticization of polystyrene but no plasticization of SIS. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 981–991, 2005
Surface photografting polymerization of vinyl acetate, maleic anhydride, and their charge‐transfer complex. V. Charge‐transfer complex (1)
Authors: Jianping Deng , Wantai Yang 
Published: December 2004

AbstractIn previous studies, the photografting polymerization of vinyl acetate (VAC) and maleic anhydride (MAH) was investigated systematically. After that, to increase the grafting rate and efficiency and make the project more practicable, a VAC–MAH binary monomer system was employed for simultaneous photografting onto the surface of low‐density polyethylene film. The effects of several crucial factors, including the composition and total concentration of the monomer solution and different types of photoinitiators and solvents, on the grafting polymerization were investigated in detail. The conversion percentage (CP), grafting efficiency (GE), and grafting percentage were measured by gravimetry. The results showed that the monomer composition played a big part in this binary system; appropriately increasing the content of MAH in the monomer feed was suited for grafting polymerization. The growth of the total monomer concentration, however, made the copolymerization faster and was unfavorable for grafting polymerization. The three photoinitiators—2,2‐dimethoxy‐2‐phenylacetophenone (Irgacure 651), benzoyl peroxide, and benzophenone (BP)—led to only slight differences in CP, but for GE, BP was the most suitable. As for the different solvents—acetone, ethyl acetate, tetrahydrofuran (THF), and chloroform—using those able to donate electrons (acetone and THF) resulted in relatively higher CPs; on the contrary, the use of the other solvents made GE obviously higher, and this should be attributed to the charge‐transfer complex (CTC) that formed in this system. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 903–909, 2005
Validation of a model of information seeking over multiple search sessions
Authors: Lin Shin‐jeng , Belkin Nick 
Published: December 2004

AbstractMost information systems share a common assumption: information seeking is discrete. Such an assumption neither reflects real‐life information seeking processes nor conforms to the perspective of phenomenology, “life is a journey constituted by continuous acquisition of knowledge.” Thus, this study develops and validates a theoretical model that explains successive search experience for essentially the same information problem. The proposed model is called Multiple Information Seeking Episodes (MISE), which consists of four dimensions: problematic situation, information problem, information seeking process, episodes. Eight modes of multiple information seeking episodes are identified and specified with properties of the four dimensions of MISE. The results partially validate MISE by finding that the original MISE model is highly accurate, but less sufficient in characterizing successive searches; all factors in the MISE model are empirically confirmed, but new factors are identified as well. The revised MISE model is shifted from the user‐centered to the interaction‐centered perspective, taking into account factors of searcher, system, search activity, search context, information attainment, and information use activities.
Effect in rats of simultaneous prenatal exposure to ochratoxin A and aflatoxin B1. I. Maternal toxicity and fetal malformations
Authors: Wangikar P.B. , Dwivedi P. , Sinha Neeraj 
Published: December 2004

AbstractOchratoxin A (OA) and Aflatoxin B1 (AFB1), the food borne mycotoxins are produced by several fungal species of the genera Aspergillus and Penicillium. To determine the teratogenic effects, these mycotoxins were administered orally either individually or in combination to the pregnant Wistar rats on days 6–15 of gestation. OA and AFB1 were dissolved in corn oil and different doses of OA (0.125, 0.25, 0.50, and 0.75 mg/kg), AFB1 (0.125, 0.25, 0.50, and 1.00 mg/kg), and a combination of OA+AFB1 (0.125+0.125; 0.25+0.50; 0.50+0.25 mg/kg) were given by gastric intubation to rats. During dosing period, the body weight and body weight gains significantly decreased at a higher dosage, in both individual and combined treatments. In all the combination treatments, the percent implants resorbed, fetal body weights, and crown‐rump lengths were comparable to those of controls and with the individual mycotoxin treatment. The number of dead fetuses was significantly increased in the high OA combination (OA+AFB1 0.50+0.25) group as compared with the other two combinations. OA and AFB1 alone and in combination caused various gross, skeletal, and visceral anomalies. The occurrence was considerably less pronounced in fetuses of AFB1 and combination groups as compared with those of OA group fetuses. The exencephaly, incomplete closure of skull, wavy and fused ribs, agenesis of the ischium bone, and enlarged renal pelvis, recorded in OA treatment and ear abnormality and incomplete ossification of skull bones observed in AFB1 when given individually, were not seen in combination groups. However, new manifestations, such as gastroschisis and syndactyly were observed and the incidence of cardiac defects was increased in fetuses due to the combined treatment. The results of the present study indicated that there is some interaction between these mycotoxins that resulted in reduced teratogenic activity of OA in the presence of AFB1. Apparently, new manifestations observed in combination treatment points to the potential threat of teratogenicity in terms of public health hazards. Birth Defects Res B 71:343–351, 2004. © 2004 Wiley‐Liss, Inc.
Making the links: child abuse, animal cruelty and domestic violence
Authors: Becker Fiona , French Lesley 
Published: December 2004

AbstractThe paper sets out the research evidence on the correlation, or the ‘links’, between child abuse, animal abuse and domestic violence, explores the evidence base available to professionals working with animals or children and describes the process of establishing a national multidisciplinary group known as the Links Group. The paper goes on to consider the challenges in setting up a working group of this kind and its subsequent progress in terms of inﬂuencing policy and practice. Finally, the authors make a series of recommendations aimed at continuing the process of change within organizations charged with the welfare of animals, children and vulnerable families. Copyright © 2004 John Wiley & Sons, Ltd.
From the Linden Flower to Linden Honey – Volatile Constituents of Linden Nectar, the Extract of Bee‐Stomach and Ripe Honey
Authors: Naef Regula , Jaquier Alain , Velluz Alain , Bachofen Boris 
Published: December 2004

AbstractHoney is produced by honeybees (Apis mellifera), which collect nectar from flowers, digest it in their bodies, and deposit it in honeycombs, where it develops into ripe honey. We studied the evolution of the volatile constituents from the nectar of linden blossoms (Tilia cordata) to honey via the ‘intermediate’ honeybee.The sampling of the contents of the honey stomach or honey sack of the bee is unique. Extracts were prepared from nectar, from the liquid of the honey stomach, and from ripe honey. The chemistry is extremely complex, and compounds spanning from monoterpenes (hydrocarbons, ethers, aldehydes, acids, and bifunctional derivatives), isoprenoids, aromatic compounds (phenylpropanoids, phenols), and products degraded from fatty acids to alkaloids, were identified. Some compounds definitely stem from the plants, whereas other interesting constituents can be attributed to animal origin. Two derivatives of decanoic acid, 9‐oxodec‐2‐enoic acid (12) and 9‐hydroxydec‐2‐enoic acid, identified in the honey are known to be constituents of the so‐called ‘Queen's pheromone’. Two metabolites of these acids were identified in the extract of the honey stomach: 8‐oxononanal (10), a new natural product, and 8‐oxononanol (11). There structures were confirmed by synthesis.Nectar and honey stomach contain many aldehydes, which, due to the highly oxidative atmosphere in the honeycomb, are found as corresponding acids in the honey. Two acids were newly identified as 4‐isopropenylcyclohexa‐1,3‐diene‐1‐carboxylic acid (14) and 4‐(1‐hydroxy‐1‐methylethyl)‐cyclohexa‐1,3‐diene‐1‐carboxylic acid (15).
14‐Methylpentadecano‐15‐lactone (Muscolide): A New Macrocyclic Lactone from the Oil of Angelica archangelicaL.
Authors: Lopes Daíse , Strobl Herbert , Kolodziejczyk Paul 
Published: December 2004

AbstractThe chemical composition of seed and root oils from Angelica archangelica L. was investigated. Analyses were performed by GC/MS and GC using two columns of different polarities (polyethylene glycol (DB‐Wax) and 5% phenyl/95% polydimethylsiloxane (HP‐5)), for the separation of several co‐eluting components. A total of 58 compounds were identified, accounting for 96.3% (seed) and 93.5% (root) of the oils, respectively. A high content of β‐phellandrene (74.7%) was found in Angelica seed oil. Root oil contained a larger amount of macrocyclic lactones (1.3%) in comparison to the seed oil (0.4%). Different harvest dates produced only slight changes in the root‐oil composition. In root oil harvested in summer, the β‐phellandrene content increased by ca. 36%, but no significant changes in the relative compositions of other components were observed. Fresh root oils were collected in five fractions (constant time intervals) during steam distillation (see Table). The highest‐boiling fraction contained 9.3% of macrocyclic lactones such as tridecano‐13‐lactone (5.0%), 12‐methyltridecano‐13‐lactone (0.4%), tetradecano‐14‐lactone (0.1%), pentadecano‐15‐lactone (3.5%), 14‐methylpentadecano‐15‐lactone (1; trace), hexadecano‐16‐lactone (trace), and heptadecano‐17‐lactone (0.2%). This is the first report of the occurrence of 14‐methylpentadecano‐15‐lactone (muscolide; 1) in a natural product.
Silylating Reagents: A Powerful Tool for the Construction of Isosteric Analogs of Highly Branched Odorants
Authors: Doszczak Leszek , Gasperi Tecla , Saint‐Dizier Alexandre , Loreto M. Antonietta , Enders Dieter 
Published: December 2004

AbstractWe have discovered that α‐[dimethyl(thexyl)silyl]acetaldehyde (=[dimethyl(1,1,2‐trimethylpropyl)silyl]acetaldehyde; 31) has a strong, woody odor. Structural analysis has shown resemblance to known odorants with similar organoleptic properties. On the basis of structureodor relationships, new and more‐powerful woody and ambery sila odorants were prepared. Further derivatization led to a set of compounds with very interesting organoleptic properties. Selected chiral compounds were also prepared stereoselectively. The influence of the absolute configuration on the olfactory properties was in agreement with theoretical assumptions. We also designed other groups of organosilicon odorants. The compounds discovered can be obtained in a few simple steps from commercially available reagents, and may find application in the fragrance and flavor industry. Their structures provide interesting data for further research on structureodor relationships.
New Woody and Ambery Notes from Cedarwood and Turpentine Oil
Authors: Panten Johannes , Bertram Heinz‐Jürgen , Surburg Horst 
Published: December 2004

AbstractThe development of a new product in the chemical industry is still driven by needs like technical properties, price/performance ratio, biodegradability, or product safety. However, in terms of improving more and more on ecological criteria, summarized under such catchphrases as sustainable development or green chemistry, another important aspect is to use renewable resources as starting materials. This is not significantly new in fragrance chemistry, and there are a lot of raw materials in the perfume oils that are derived from molecules of renewable resources. Two commonly used materials are: longifolene (from turpentine oil) and cedrene (from cedarwood oil). These compounds are very suitable for the synthesis of woody and ambery notes, and even though it seemed that all possibilities were exhausted, it is actually still feasible to discover new molecules with excellent olfactory properties such as Ambrocenide® (50a), which is available in three steps from α‐cedrene. Some of these molecules will be treated in this review, both with respect to synthesis as well as structural and sensory aspects.
New Macrocyclic Musk Compounds
Authors: Matsuda Hiroyuki , Watanabe Shinya , Yamamoto Kenichi 
Published: December 2004

AbstractThe syntheses and olfactory evaluations of eight new macrocyclic musks with a 1,6‐dioxa structure (1a–d and 1′a–d) as well as of twelve optically active 3‐methyl macrolides (5a–c and 5′a–c) are reported. These macrocycles were synthesized via intramolecular metathesis mediated by the Grubbs catalyst. Despite the absence of a CO function, the 1,6‐dioxa compounds, both unsaturated (1) and saturated (1′), possess musky odors similar to those of macrocyclic ketones and lactones. Especially 16‐membered rings were found to display an intense and pleasant musk character. However, in the case of optically active 3‐methyl macrolides (5, 5′), only the (R)‐configured 15‐ and 16‐membered rings had intense and pleasant musk notes.