bluuebunny/crossref_metadata_2025 huggingface dataset:
Gas chromatography‐mass spectrometry following pressurized hot water extraction and solid‐phase microextraction for quantification of eucalyptol, camphor, and borneol in Chrysanthemum flowers
Authors: Dong Ling , Wang Jiyao , Deng Chunhui , Shen Xizhong
Published: December 2006

Chrysanthemum flower is a common traditional Chinese medicine (TCM). In this work, pressurized hot water extraction (PHWE) followed by headspace solid‐phase microextraction (HS‐SPME) and GC‐MS was developed for the determination of three main active volatile compounds of eucalyptol, camphor, and borneol in Chrysanthemum flowers from four different growing areas in China by internal standard method. The parameters of PHWE and HS‐SPME were optimized. The method was also validated. The results showed that PHWE‐SPME‐GC‐MS is a simple, rapid, efficient, and solvent‐free technique for the quantitative determination of eucalyptol, camphor, and borneol in TCMs and is potentially useful for the TCM quality assessment.
Analysis of aromatic amines as N‐propoxycarbonyl derivatives by gas chromatography with nitrogen‐phosphorus selective detection
Authors: Kataoka Hiroyuki , Miyake Mina , Mitani Kurie
Published: December 2006

A selective and sensitive method for the analysis of aromatic amines by GC was developed. Aromatic amines were converted to their N‐n‐propoxycarbonyl derivatives and measured by GC with nitrogen‐phosphorus selective detection (NPD) using an HP‐5 fused‐silica capillary column. The derivatives of the 20 aromatic amines provided excellent NPD responses, and were resolved both quantitatively and reproducibly within 15 min. The calibration curves for aromatic amines in the range 20–500 ng were linear and the detection limits at an S/N of 3 were ca. 19–139 pg injected. This method was applied successfully to combustion smoke and human urine samples, and analyzed without any interference from coexisting substances.
Simultaneous determination of catecholamines and amino acids by micellar electrokinetic chromatography with laser‐induced fluorescence detection
Authors: Zhou Lei , Wang Shumin , Tian Kan , Dong Yuming , Hu Zhide
Published: December 2006

A selective and sensitive method was developed for separation and simultaneous determination of catecholamines and amino acids by MEKC with LIF. Interestingly enough, such work has been firstly performed on catecholamines derivatized with 4‐chloro‐7‐nitro‐2,1,3‐benzoxadiazole and the detailed derivatization mechanism was discussed. After derivatization at 60°C for 20 min, NBD‐labeled catecholamines and amino acids were separated in a buffer system containing 10 mM sodium tetraborate‐Na2HPO4, 20 mM SDS, and 10% v/v ACN at pH 9.75. SDS micelles were employed to improve the fluorescence intensity of catecholamine derivatives efficiently. Under optimum conditions, two catecholamines and 11 amino acids were separated in a short 13 min analysis time and the RSDs for migration time and peak area were less than 0.60 and 6.50%, respectively. The method was successfully applied for the quantification of catecholamines and amino acids in Portulaca oleracea L., human urine sample, and mixed injection sample.
Comparison of various extraction techniques for isolation and determination of isoflavonoids in plants
Authors: Bajer Tomáš , Adam Martin , Galla Lubomír , Ventura Karel
Published: December 2006

In the present paper, the following extraction techniques have been used for extracting isoflavonoids from the species Matricaria recutita, Rosmarinus officinalis, Foeniculum vulgare, and Agrimonia eupatoria L.: supercritical fluid extraction (SFE), pressurized fluid extraction, matrix solid phase dispersion, ultrasonic extraction in an ultrasonic bath (USE) and by means of an ultrasonic homogeniser (HOM), extraction by means of Soxhlet apparatus (SOX), and solid phase extraction. Experimental optimization of all techniques has been carried out using a soybean flour. Subsequent analyses of the extracts were carried out by liquid chromatography with UV detection. The maximum yields of daidzein and genistein were obtained by extraction with the SOX, USE, and HOM techniques. The maximum yields of apigenin and biochanin A from herb samples were obtained by SFE.
Sustained Epstein-Barr Virus Detection in Paediatric Liver Transplantation. Insights Into the Occurrence of Late PTLD
Authors: D'Antiga Lorenzo , Del Rizzo Monica , Mengoli Carlo , Cillo Umberto , Guariso Graziella , Zancan Lucia
Published: December 2006

Epstein-Barr virus (EBV) infection is the main cause of post-transplant lymphoproliferative disease (PTLD). Little is known on chronic carrier state and its relation with late PTLD. We aimed to study EBV infection in the long-term after paediatric liver transplantation (OLT). We conducted a retrospective review of 34 children monitored for a median of 5.8 years (range 1.5-17.7). 21 were IgG seronegative (group A) and 13 seropositive (group B) before OLT. Primary infection was the appearance of VCA-IgM or VCA-IgG or Real-Time Polymerase Chain Reaction (RT-PCR) in patients previously IgG seronegative; positive VCA-IgM or EA-IgG or RT-PCR lasting longer than 6 months was defined sustained viral detection (SVD). 18/21 patients of group A had a primary infection at a median time of 3 months after transplant (0.5-60). 14/18 of group A and 0/13 of group B had a SVD (P < 0.0001). Viral loads greater than 500 copies/10mononuclear cells occurred in 12/18 patients in group A and 0/13 patients in group B (P < 0.0001). The 3 patients who developed late PTLD (median time after OLT 47 months, range 15-121) were from group A, and presented with SVD before developing PTLD. In conclusion, EBV infection in seronegative patients at OLT is associated with greater viral loads and sustained viral detection. Late PTLD occurred only in naïve patients with markers of SVD. Three to 4 monthly long-term monitoring of EBV in pre-OLT naïve patients might help preventing the occurrence of late PTLD. Liver Transpl 13:343-348, 2007. 2006. © 2006 AASLD.
Comparison of Clinical Outcomes in Chronic Hepatitis B Liver Transplant Candidates with and Without Hepatocellular Carcinoma
Authors: Wong Stephen N. , Reddy Rajender K. , Keeffe Emmet B. , Han Steven-Huy , Gaglio Paul J. , Perrillo Robert P. , Tran Tram T. , Pruett Timothy L. , Lok Anna S.F.
Published: December 2006

Patients with hepatocellular carcinoma (HCC) receive a higher MELD score and may undergo liver transplantation (OLT) earlier compared to patients with cirrhosis, potentially decreasing waiting list mortality. However, post-OLT survival may be reduced by recurrence of HCC. We compared clinical outcomes between patients with HBV-cirrhosis and no HCC and patients with HBV-HCC. A total of 279 patients (HBV-cirrhosis = 183; HBV-HCC = 96) in the US HBV-OLT study were followed for a median of 30.2 months from listing. Patients with HCC were older, more likely to be Asian, and had less severe liver impairment than patients with HBV-cirrhosis. Despite a higher rate of OLT in patients with HCC (78.1% vs. 51.4%; P < 0.001), intention-to-treat (ITT) survival (73% vs. 78%) and survival without OLT (82% vs. 79%) at 5 years were similar for patients with and without HCC. Cox regression analysis identified higher albumin, lower MELD, no HCC at listing, and being transplanted to be associated with better ITT survival. Ninety-four patients with HCC (including 19 new HCC) and 75 with HBV-cirrhosis underwent OLT. Post-OLT survival (83% vs. 90%) and HBV recurrence (11% vs. 10%) at 3 years were similar, while disease (HBV and/or HCC) recurrence (19% vs. 10%; P = 0.043) was higher in patients with HBV-HCC vs. HBV-cirrhosis. Disease recurrence was the only independent predictor of post-OLT survival. In conclusion, despite more advanced liver disease and a lower rate of transplantation, ITT survival of patients listed for HBV-cirrhosis was comparable to those with HBV-HCC, possibly related to beneficial effects of antiviral therapy. Liver Transpl 13:334-342, 2007. © 2006 AASLD.
Structure analysis of Antonovsky's sense of coherence from an epidemiological mental health survey with a brief nine‐item sense of coherence scale
Authors: Klepp Olav Martin , Mastekaasa Arne , Sørensen Tom , Sandanger Inger , Kleiner Robert
Published: December 2006

Antonovsky has proposed the sense of coherence (SOC) as a crucial factor that protects against symptoms of mental disease. A central issue in research on the SOC construct is whether this is most appropriately considered as one‐dimensional or three‐dimensional with comprehensibility (C), manageability (Ma) and meaningfulness (Me) as separate dimensions. In this paper we address this issue by means of confirmatory factor analysis of a shortened nine‐item version of Antonovsky's original 29‐ and 13‐items Sense of Coherence Scale (SOCS‐29), using epidemiological data from a mental health survey of adults in local communities (N = 1,062). In addition to analysing the internal structure of the SOC items, we examine the association between estimated factor scores and variables expected to be statistically related to SOC. Goodness‐of‐fit indices were very good for the three‐factor model but acceptable even for the one‐factor model. In the three‐factor model, however, the factors were found to be very highly or, with regard to Ma and C, even perfectly correlated. Moreover, the factor scores had very similar correlations with measures of psychological wellbeing, depression and anxiety and they are also very similarly related to age (and none of them are related to gender). We therefore conclude in favour of a one‐factor model. Copyright © 2006 John Wiley & Sons, Ltd.
1H and 13C chemical shifts for some tetrasubstituted 2,5‐diaryl di‐ and tetrahydrofuran derivatives
Authors: Martinet S. , Méou A. , Brun P.
Published: December 2006

The 1H and 13C NMR chemical shifts of four 2,5‐diaryltetrahydrofuran derivatives and their dihydro precursors were assigned completely with certainty using a concerted application of one‐ and two‐dimensional experiments (DEPT, gs‐COSY, gs‐HMQC and gs‐HMBC) Copyright © 2006 John Wiley & Sons, Ltd.
Tobacco smoke particulate matter chemistry by NMR
Authors: Barsanti Kelley C. , Luo Wentai , Isabelle Lorne M. , Pankow James F. , Peyton David H.
Published: December 2006

The submicron liquid droplets constituting the particulate matter of mainstream tobacco smoke (PMMTS) are viscous and of a composition that is complex and poorly understood. PMMTS is often ∼80% w/w ‘tar’ where ‘tar’ = total PMMTS− (nicotine + water). Many of the chemical agents in MTS responsible for smoking‐related cancers are found at least partially in the PMMTS portion of MTS. The properties of PMMTS vary with brand and with puffing patterns. The chemical forms and total levels of nicotine, the identities/levels of other compositionally dominant compounds, and the identities/levels of carcinogens are of interest. Most studies of the composition of PMMTS have involved extraction then chromatography. Such methods allow the determination of low‐level constituents, but alter the samples such that direct information regarding chemical conditions within the PMMTS cannot be obtained. Here, we utilize nuclear magnetic resonance spectroscopy (NMR) to examine native PMMTS in conventional cigarettes, including measurements of the brand‐dependent fraction of PMMTS nicotine that is in the free‐base form (increasing this fraction in inhaled tobacco smoke affects the rates of the processes governing nicotine deposition in the respiratory tract, and so has implications for smoking behavior and addiction). We also demonstrate the use of NMR for characterizing the composition of PMMTS (including the levels of selected cigarette additives) when the cosolvent DMSO‐d6 is added to improve spectral resolution. The native and solvent‐assisted results open the door to a range of future studies. Copyright © 2006 John Wiley & Sons, Ltd.
A 1H‐NMR thermometer suitable for cryoprobes
Authors: Findeisen M. , Brand T. , Berger S.
Published: December 2006

Most established NMR thermometers rely on temperature‐dependent chemical shift differences measured from samples that are either neat or concentrated solutions (e.g. ethylene glycol, methanol). These are unsuitable for modern cryoprobes on account of strong radiation damping resulting from the high Q of the probe. Using perdeuterated methanol, we established a relationship between the chemical shift difference and temperature, and we show that this relationship is well fitted by a quadratic equation. The actual temperature within a sample tube in the probe was verified using a Pt‐100 resistor. Copyright © 2006 John Wiley & Sons, Ltd.
High‐performance parallel simulation of structure degradation using non‐local damage models
Authors: Germain Norbert , Besson Jacques , Feyel Frédéric , Gosselet Pierre
Published: December 2006

Simulating damage and failure of metallic or composite structures often fails when using standard finite element discretizations and a Newton–Raphson solving procedure. The difficulties arise from an uncontrolled mesh dependency caused by damage localization, to structural instabilities and to an increase of computational costs. The first problem can be overcome by using non‐local damage constitutive equations together with a specific finite element model. The second problem can then be solved with an arc‐length method which manages instabilities and snap‐backs. They are caused by the loss of strength‐carrying capacity of the damaged material. Finally, the whole computational scheme is parallelized. The main contribution of this paper consists in bringing together the three numerical techniques: non‐local material model; piloting and parallel computations. The resulting numerical scheme allows to go beyond the overly simplistic cases often encountered in the literature. It allows robust industrial simulations with a high number of degrees of freedom, both in two and three dimensions, and deepened studies involving a large number of simulations. Copyright © 2006 John Wiley & Sons, Ltd.
Computation of Screening Phenonema in a Vertical Tumbling Cylinder
Authors: Alkhaldi Hashem , Eberhard Peter
Published: December 2006

Granular materials are an integral part of our environment. Due to their wide variety of applications in industrial and technological processes, they have captured a great interest in the recent research, see [1] and [2]. The related studies are often based on numerical simulations and it is considered as challenging to investigate computational phenomena of dense granular systems. Particle screening is an essential technology in many industrial fields and important in granular studies. The particular problem of interest is the separation of round shape particles of different geometrical sizes using a rotating tumbling vertical cylinder. The concept of discrete element method (DEM) that considers the motion of each single particle individually is applied in this study. Particle‐to‐particle and particle‐to‐wall collisions will appear under the tumbling motion of the rotating structure. The normal and frictional forces between particles themselves and particles and surrounding walls of the structure are calculated according to the rules of a penalty method, which employs spring‐damper models for this purpose. As a result of collisions, the particles will dissipate kinetic energy due to the normal and frictional contact losses. Particle distribution and sifting rate of the separated particles have been studied taking into consideration different rotational speeds of the machine, various damping and frictional coefficients and different sizes of holes in the sifting plates at different levels of the structure. In an attempt to better understand the mechanism of the particle transport between the different layers of the sifting system, different computational studies have been performed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the use of Euler parameters in multibody dynamics
Authors: Betsch Peter
Published: December 2006

Euler parameters (or unit quaternions) are known to be well‐suited for the singularity‐free description of finite rotations. Despite of this advantageous feature, the majority of rigid body integrators do not rely on Euler parameters. This observation might be closely related to the fact that the four Euler parameters are not independent. Thus the equations of motion in terms of Euler parameters inevitably assume the form of differential‐algebraic equations (DAEs). Since the early investigations dealing with Euler parameters in multibody dynamics, numerical methods for DAEs have improved significantly. Nowadays robust energy consistent integrators are available which exactly reproduce the property of workless constraint forces. The purpose of the present work is to revisit the use of Euler parameters in the light of state‐of‐the‐art integration schemes. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Some actual results of tire research in connection to the DFG Sonderforschungsbereich 181 (1986‐1996)
Authors: Böhm Friedrich , Duda Albert , Wille Ralf
Published: December 2006

Applications of 2D and 3D tire models for car dynamics, landing of airplanes and off‐road vehicles are presented. For a big agricultural tire on pliable ground a multi‐point measurement device in the inner of the tire was developed, in order to verify computed rolling deformations. The measurement results in a soil channel at TU Munich also were compared with results of flat band testing. Theoretical investigations of tire behaviour were carried out on the basis of thin layered shell theory, together with Russian and Ukrainian scientists. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of a deformable multibody system with hydraulics and control
Authors: Dibold Markus , Gerstmayr Johannes
Published: December 2006

Numerous contributions have been made concerning multibody systems, hydraulic actuators or the design of feedback controllers. A system that combines these fields has been studied rarely. In the present work the systematic simulation of an entire machine, which consists of structural mechanical elements where single masses are transported, hydraulic actuation systems and a closed loop controller is studied. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effiziente Simulation von Mehrkörpersystemen mit Kontaktbedingungen ‐ O(n) Verfahren
Authors: Gattringer Hubert , Höbarth Wolfgang , Bremer Hartmut
Published: December 2006

Aufgrund der immer größer werden Komplexität von dynamischen Systemen in Forschung und Industrie ist man an einer effizienten Simulation interessiert. Bei der dynamischen Modellierung von baumstrukturierten Mehrkörpersystemen entstehen hochgradig nichtlineare Bewegungsgleichungen. Dabei wird von einer Beschreibung in Minimalform ausgegangen. Der Rechenaufwand zur Invertierung der Massenmatrix ist enorm. Er steigt mit kubischer Ordnung (O(n)3) der Freiheitsgrade. Bei einer Modellierung des Mehrkörpersystems über die Projektionsgleichung in Subsystemdarstellung kann ein O(n) Verfahren hergeleitet werden. Werden einzelne Baugruppen (Subsysteme) zusammengefasst, lässt sich das Problem geeignet strukturieren, und über die den Subsystemen zugeordneten beschreibenden Geschwindigkeiten erhält man gut interpretierbare Zwischenergebnisse. Als Subsysteme können nicht nur starre Einheiten (z.B. Motor Getriebe Einheit), sondern auch hybride Systeme (z.B. Motor mit elastischem Balken) zum Einsatz kommen. Anstatt wie bei herkömmlichen Verfahren die Gesamtmassenmatrix invertieren zu müssen, kommt der O(n) Algorithmus mit einer Matrixinvertierung vom Relativfreiheitsgrad pro Subsystem aus. Bei einer Motor Getriebe Einheit ist das eine quadratische Matrix (Motor ‐ und Armwinkel), bei hybriden Systemen kommen als Relativfreiheitsgrade noch die Ritz Koeffizienten dazu. Werden bei dem Mehrkörpersystem zusätzliche Kontakte aktiv, so kann das mithilfe einer Kontaktkraft (Lagrangescher Parameter) ins Modell aufgenommen werden. Auch für diesen Fall kann ein effizienter Algorithmus angegeben werden, der ohne eine Invertierung der Massenmatrix auskommt. Beim Übergang zum Kontaktfall tritt unweigerlich ein Stoß auf. Dieser wird ebenfalls im Sinne des O(n) Verfahrens behandelt. Als Anwendungsbeispiel wird auf eine zweibeinige Laufmaschine eingegangen. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Application of the discrete null space method to domain decompositionand large deformation contact problems
Authors: Hesch Christian , Betsch P.
Published: December 2006

We aim at the development of energy consistent ‘mechanical’ integrators for the differential‐algebraic equations (DAEs) associated with the contact problems under consideration. First steps towards the energy consistent time integration of frictionless dynamic contact problems can be found in the works by Laursen & Chawla [4], Armero & Petöcz [1] and Laursen & Love [5]. Energy consistent mechanical integrators have been recently developed for DAE‐formulations of constrained mechanical systems (e.g. Gonzalez [3]). These works are based on the direct discretization of the underlying DAEs leading to a saddle point system to be solved in each iteration of the iterative solution procedure. Due to the presence of Lagrange multipliers this approach leads to a large number of unknowns and potential conditioning problems. To remedy these drawbacks the discrete null space method (Betsch [2]) has been recently developed. We apply the discrete null space method to both domain decomposition in the framework of nonlinear elastodynamics and large deformation contact problems. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Methodenvergleich bei der Modellierung eines Mini Segway
Authors: Höbarth Wolfgang , Gattringer Hubert , Bremer Hartmut
Published: December 2006

Bei einem Mini Segway handelt es sich um ein einachsiges Fahrzeug mit instabilem Aufbau. Bei der Modellierung von Fahrzeugen ohne Quergleiten der Rädermüssen nichtholonome Bindungen eingeführt werden. Es gibt verschiedeneMöglichkeiten, diese Bindungen zu berücksichtigen. Anhand eines Segway Modells werden unterschiedliche Vorgehensweisen zur Modellbildung aufgezeigt. Als analytische Methode wird Lagrange II verwendet. Hier muss die Bindung auf Geschwindigkeitsebene vorerst offen gelassen werden. Sie kann aber nachträglich mittels Kontaktkraft (Lagrangescher Parameter) oder mittels Nachprojektion in die freien Geschwindigkeitsrichtungen (Maggi Gleichung) eingebracht werden. Als synthetische Methode zum Aufstellen der Bewegungsgleichung wird die Projektionsgleichung verwendet. Bei dieser Methode können direkt die nichtholonomen Minimalgeschwindigkeiten verwendet werden. Zusätzlich wird versucht, die Bewegungsgleichung mit Hilfe von reduzierten Koordinaten zu ermitteln. Hierbei treten bei der Verwendung von analytischen Methoden große Probleme auf, da die verwendeten, reduzierten Koordinaten die Geschwindigkeitsbindung bereits implizit erfüllen, was andererseits die Projektionsgleichung zu einem universell einsetzbaren Werkzeug macht. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An Experimental and Numerical Study of Deformable Bodies Contact
Authors: Jiang Yu , Eberhard Peter
Published: December 2006

This study deals with the impact of a rotating disc elastically striking a strip. We establish an experimental setup including a disc with a throwing machine controlled by a dSPACE‐Autobox to generate the translational and rotational motions of the disc, a properly fixed strip and a high‐speed digital camera system with an image processing package to capture kinematical data of the disc. The effects of strip flexibility and disc initial normal velocity before impact are investigated in detail. For interpreting the experimental results a hybrid impact model is developed which can provide not only generally good predictions compared with measurements but also some insight into the influences of strip flexibility and disc initial motions. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Efficient integration of flexible multibody dynamics
Authors: Leyendecker S. , Betsch P. , Steinmann P.
Published: December 2006

The modelling of flexible multibody dynamics as finite dimensional Hamiltonian system subject to holonomic constraints constitutes a general framework for a unified treatment of rigid and elastic components. Internal constraints, which are associated with the kinematic assumptions of the underlying continuous theory, as well as external constraints, representing the interconnection of different bodies by joints, can be accounted for in a likewise systematic way. The discrete null space method developed in [0] provides an energy‐momentum conserving integration scheme for the DAEs of motion of constrained mechanical systems. It relies on the elimination of the constraint forces from the discrete system along with a reparametrisation of the nodal unknowns. The resulting reduced scheme performs advantageously concerning different aspects: the constraints are fulfilled exactly, the condition number of the iteration matrix is independent of the time step and the dimension of the system is reduced to the minimal possible number saving computational costs. A six‐body‐linkage possessing a single degree of freedom is analysed as an example of a closed loop structure. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Three‐dimensional modelling of discrete particles by superellipsoids
Authors: Lillie Claudia , Wriggers Peter
Published: December 2006

Discrete Elements are used for the simulation of granular materials (sand, ballast) as well as for molecular assemblies. Circles (2D) and spheres (3D) are often used in literature on the Discrete Element Method (DEM) however they represent a strong idealisation of the real geometry. Superellipsoids provide the opportunity to generate a wide variety of three‐dimensional geometrical shapes (e.g. sphere, cube, cylinder).

The motion of each particle is described by means of rigid body dynamics. Suitable numerical integration methods are necessary which are able to conserve the essential physical quantities like momentum energy etc.. Possible choices are e.g. the explicit Verlet‐Leapfrog method for the translation and the explicit fourth order Runge‐Kutta method for the rotation. The implemented contact formulation takes damping as well as friction into account. Efficient implementation of the contact search is the main aim of this part of the work. It is subdivided into the neighbourhood search and the local search. A bisection algorithm is used to calculate the gap between two superellipsoids within the search. For the neighbourhood search two binning algorithms were implemented and compared for several packages of particles. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Kompensation der Lagefehler der Inertialsensoren in einer IMU
Authors: Meinicke Alexander , Woernle Christoph , Wagner Jörg
Published: December 2006

Die Sensoren in Inertial Measurement Units (IMU) weisen Lagefehler auf. Werden diese Lagefehler nicht identifiziert und rechnerisch kompensiert, können erhebliche systematische Messfehler entstehen. Im vorliegenden Beitrag werden die Kompensationsgleichung sowie die erforderliche Genauigkeit bei der Identifikation der Lagefehler hergeleitet. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Problem of unilateral constraints in the dynamics of the floor loaded with a machine
Authors: Mironowicz Władysław , Sęk Marcin
Published: December 2006

The engineering practice indicates that in industrial ferro ‐ concrete constructions there are various irregularities and damages which may hare significant influence on it's stiffness and consequently on it's vibration. In the paper one of fore ‐ mentioned issues i.e. weakening or loss of connection between selected parts of the structure is considered. More precisely it is the problem of unilateral constraints in elastic constraints between the ferro ‐ concrete slab floor and the machine placed on it. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ein innovatives Sensorkonzept zur “Schmerzdetektierung”
Authors: Ostermeyer G. P. , Schiefer F.
Published: December 2006

Ein Zusammenhang von Schmerz und technischen Systemen ist bislang nahezu unerforscht. Dabei lässt sich eine bestimmte, physiologisch beschriebene Schmerzart durchaus auf technische Anwendungen beispielsweise in der Robotik oder Prothetik abbilden. Der nozizeptive Schmerz dient Lebewesen im Allgemeinen als Warnsystem und wird auch als sinnvoller Schmerz bezeichnet. Das Ziel ist es, auf technischem Wege diese Schmerzart detektieren zu können und damit weitere Kriterien zur Beurteilung der Funktion von Systemen zu finden. Das Sensorkonzept beruht auf der Idee, dass zwischen den Eigenschaften von Schmerz und Wärme Analogien existieren [3]. Die Erhöhung bestimmter Eigenschaften äußerer Einwirkungen führt zu einer Vergrößerung sowohl des Schmerzes als auch der Wärme. Das Ausbleiben der Einwirkungen führt zum Nachlassen des Schmerzes bzw. zum Abklingen der Wärme. Die Sensoridee führt zur Anwendung der Mesoskopischen Vielteilchentheorie [1, 2], mit der u. a. die Energieumwandlung in Wärmeenergie bei Stoß‐ und Reibvorgängen in den Grenzschichten der Kontaktkörper thermodynamisch korrekt beschrieben werden kann. Mit Hilfe des entwickelten Sensorkonzeptes wird ein Energieeintrag gemessen, der implizit frequenzselektive Informationen über die Ruckbeanspruchung enthält. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Autonomer Mobiler Roboter mit Scara‐Armeinheit
Authors: Stadlbauer Klaus , Bremer Hartmut
Published: December 2006

Autonome Mobile Roboter sind heutzutage schon vielfältig im Einsatz. Ob zum Reinigen von Flughäfen, zum Transport von Gütern oder zum Erkunden fremder Planeten, sie alle haben gemein, dass sie autonom agieren und reagieren müssen. Die Modellierung dieses nichtholonomen Roboters welcher von der Kon.guration einem konventionellen Automobil entspricht erfolgt mit Hilfe der Projektionsgleichung in Subsystemdarstellung. Der große Vorteil der Projektionsgleichung liegt darin, dass die nichtholonomen Bindungen implizit in diesem System enthalten sind. Weiters ist das Verfahren sehr.exibel bei der Wahl der Referenzkoordinatensysteme. Die SCARA‐Armeinheit (SCARA = Selective Compliance Assembly Robot Arm) wird in vertikaler Lage als Manipulator angebracht. Hier sieht man den Vorteil der Projektionsgleichung in Subsystemdarstellung, da ohne großen Rechenaufwand beliebig viele weitere Arme hinzugefügt werden können. Die Bewegungsgleichung wird in den Zustandsraum transformiert und mittels einer nichtlinearen Zustandsrückführung eingangs‐/ausgangslinearisiert. Mit Hilfe eines diesem linearisierten System überlagerten linearen Reglers kann das Gesamtsystem geregelt werden. In diesem System übernimmt die Steurung bzw. Regelung eine Embedded‐ Computer Plattform, die über das Echtzeitsystem RT‐Linux angesteuert werden soll. Natürlich muss hierbei gewährleistet werden, dass die Rechenzeit der Plattform den Anforderungen der Sensoren, der Pfadplanung und der Regelung gerecht wird. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Regularization of 2D frictional contacts for rigid body dynamics
Authors: Stamm W. , Fidlin A.
Published: December 2006

Classic rigid body mechanics does not provide frictional forces acting in a 2D contact interface between two bodies during sticking. This is due to the statical undeterminacy related with this problem. Many technical systems, e.g. disk clutches, have such surface‐to‐surface contacts and it is sometimes desirable to treat them as rigid body systems despite the 2D contact. Alternatively it is possible to model the systems using elastic instead of rigid bodies, but this might lead to certain drawbacks. Here a new regularization model of such 2D contacts between rigid bodies is proposed. It is derived from a material model for elasto‐plasticity in continuum mechanics. Only dry friction is taken into account. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimization of spatial tracks using a morphing approach
Authors: Tändl Martin , Kecskeméthy Andrés
Published: December 2006

This paper describes an approach for optimizing multibody systems involving spatial tracks, addressing the problem of finding an optimal set of design parameters when no good initial guess is available. In this setting, it is common that, due to nonlinearities of the objective function and singularities in the kinematic model, the optimization fails to converge or to find feasible points at all. The present paper presents a three‐stage procedure for sequentially guiding a standard optimization routine from an arbitrary initial guess to the optimal configuration. The approach has been tested when optimizing real roller coaster tracks with respect to passenger acceleration and compared with a genetic algorithm implementation, showing that objective function morphing renders faster for the regarded type of systems. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Rotational motion of a discretized buckled beam
Authors: Troger H. , Pissarev A. , Steindl A.
Published: December 2006

We study a simple discretized model of a vertical cylindrical beam with circular cross‐section which is clamped at its lower end and free at its upper end. If the beam is longer than a critical length the initially straight configuration will loose its stability and the beam will buckle due to its own weight. Now the base of the buckled beam is rotated about its vertical axis. Several different families of steady state motions are detected for the undamped system. Their stability is investigated. Moreover it is shown that there is a big difference in the behavior of the discretized model of the beam whether internal damping is included in the model or not. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Energy consistent time integration of planar multibody systems
Authors: Uhlar Stefan , Betsch Peter
Published: December 2006

The planar motion of rigid bodies and multibody systems can be easily described by coordinates belonging to a linear vector space. This is due to the fact that in the planar case finite rotations commute. Accordingly, using this type of generalized coordinates can be considered as canonical description of planar multibody systems. However, the extension to the three‐dimensional case is not straightforward. In contrast to that, employing the elements of the direction cosine matrix as redundant coordinates makes possible a straightforward treatment of both planar and three‐dimensional multibody systems. This alternative approach leads in general to differential‐algebraic equations (DAEs) governing the dynamics of rigid body systems. The main purpose of the present paper is to present a comparison of the two alternative descriptions. In both cases energy‐consistent time integration schemes are applied. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Finite Swelling with Weakly Fulfilled Boundary Conditions
Authors: Acartürk A. , Ehlers W. , Markert B.
Published: December 2006

Biological soft tissues exhibit a swelling behaviour and consist of multiple phases, a solid phase composed of collgagen fibers and charged PGA chains and a fluid phase composed of the liquid solvent and the ions of dissolved salt.

In this contribution, the Theory of Porous Media (TPM) model consists of four constituents, a charged solid and an aqueous solution composed of water and the ions of dissolved salt. The solid is modelled by a finite elasticity law accounting for the multiphasic micro structure, whereas the fluid is considered as a viscous Newtonian fluid. One finally ends up with the volume balance of the fluid, the concentration balance of the cations, the momentum balance of the overall mixture. The resulting set of partial differential equations is solved within the framework of the FEM. Therefore, the weak forms are derived and the resulting set of equations for the primary variables pore pressure p, cation concentration c and solid displacement uS , is implemented into the FE tool PANDAS. Finally, a three dimensional example of a swelling hydrogel disc is shown. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Study of the Human Body Vibrations for the Seated Vehicle Driver
Authors: Arghir Mariana , Rodean Simona
Published: December 2006

The paper presents some aspects about the dynamic response of the human body subjected to the vertical vibration in the travel inside the auto vehicle. There is a model presented in the specialized literature. This is transformed for the given study because was necessary to realize the vertical vibration along the human body. There are two different studies: using a linear lumped parameter systems seat ‐ human body model; using a nonlinear lumped parameter systems seat‐human body model. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling of Eigenstresses and Damage in Arterial Walls
Authors: Balzani Daniel , Schröder Jörg , Gross Dietmar
Published: December 2006

An anisotropic damage model is used for the numerical simulation of an overstretched artery taking into account eigenstresses occurring in unloaded configurations of arteries. In order to guarantee the existence of minimizers we use a polyconvex energy function for the description of the hyperelastic behavior in the physiological range of deformations in arterial walls. The basic assumption underlying the applied damage model is that the damage occurs mainly in fiber direction. As a numerical example we consider the cross‐section of a diseased artery and apply a high internal pressure in order to obtain the damage distribution at the overstretched configuration. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An anisotropic viscoelastic soft tissue model at large strains
Authors: Görke Uwe‐Jens , Günther Hubert , Bucher Anke , Kreißig Reiner
Published: December 2006

Soft biological tissues represent complex inhomogeneous, and as a rule multiphase materials subjected to large strains under in vivo mechanical conditions. Apart from a number of other structural‐related features they are characterized by a ratedependent material behavior which is attributed to fluid‐solid interactions as well as intrinsic viscoelastic properties of the solid matrix. The authors propose to model rate‐dependent phenomena of the solid phase of soft biological tissues within the context of a thermodynamically consistent phenomenological material approach resulting from an overstress concept. Due to the presence of directed fibrous constituents soft tissues should be considered as anisotropic materials. Therefore, the viscous overstress model has been completed by a transversely isotropic approach. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theory and Implementation of Time‐Dependent Fibre Reorientation in Transversely Isotropic Materials
Authors: Himpel Grieta , Menzel Andreas , Kuhl Ellen , Steinmann Paul
Published: December 2006

Transversely isotropic materials are commonly described by one characteristic direction in the material configuration, which commonly is assumed to be constant. However, for some applications it makes sense to consider a reorientation of the characteristic direction, as for instance the orientation of biological materials adapts to the mechanical loading, see e.g. Kuhl et al. [4]. Other examples are piezoelectric materials, which reorient due to electric or mechanical loading, as described in Smith [7], and liquid crystals changing their orientation on account of electric or magnetic fields, see Ericksen [1]. Furthermore simulations with a reorientation of the characteristic direction can be used in the context of optimisation of composites. In this contribution we restrict ourselves to the modelling of hyper‐elasticity and assume a time dependent reorientation of the characteristic direction with respect to the principal strain directions, see for instance Menzel [5]. Thereby we concentrate on the numerical implementation into a finite element code. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Suitable initial conditions for multiphasic FE computations of spinal discs
Authors: Karajan N. , Ehlers W. , Markert B.
Published: December 2006

The intervertebral disc (IVD), as a complex representative of charged, hydrated biological soft tissues, is of great research interest regarding numerical simulation techniques. Herein, especially the Finite Element Method (FEM) plays a major role in combination with a macroscopic model based on the Theory of Porous Media (TPM). Following this, two phases are introduced: the extracellular matrix exhibiting a nonlinear viscoelastic behavior and the viscous interstitial fluid. Furthermore, the resultant solid and fluid phases are electrochemically active by carrying fixed negative charges and containing dissolved ions and cations, respectively. This characteristic causes an osmotic pressure (Donnan osmosis), which is superimposed with the hydraulic contribution to a total pore pressure.

In this contribution two numerical simulations of a free swelling experiment with different initial conditions are discussed. Herein, one can proceed from an overall stress‐free reference configuration, which leads to a prestressed but undeformed solid skeleton. Secondly, a non stress‐free initial state is investigated, which will be computed to an equilibrium state between the osmotic pressure and the solid extra stress leading to a deformed and prestressed solid skeleton. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Identification of The Aortic Leaflet Valve Material
Authors: Konderla Piotr , Krzysztof Patralski
Published: December 2006

Abstract
On the Description of Growth in Saturated Living Tissues
Authors: Ricken Tim
Published: December 2006

A comprehensive model for biological tissues must include the anisotropic tissue structure, the interstitial liquid wich saturated the tissue and the growth mechanism of the tissue. In the present contribution this is done by use of a three phasic model with a solid, liquid and nutrient phase in the framework of the porous media theory (TPM). In order to characterize the transversal isotropic skeleton behavior, an invariant formulation of the Helmholtz free energy function and the permeability tensor is suggested. The growth mechanism is characterizes by a mass transfer between the nutrient and solid phase. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Joint And Muscle Forces During Clenching
Authors: Rues Stefan , Lenz Jürgen , Schindler Hans J. , Schweizerhof Karl
Published: December 2006

The masticatory system is highly redundant. Therefore, complete knowledge about the activation patterns of the chewing muscles belonging to a specific resultant bite force can only be gained either by simultaneous force‐ and EMG‐measurement or with the help of optimization strategies. In this study, such EMG and force measurements were carried out with 10 test persons and the results compared to those computed with several objective functions.

The results show an increase of the joint forces with an increase of the horizontal component of the resultant bite force. The test persons seem to favor energy minimization as control mechanism. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Kinematik und Dynamik aus experimentell ermittelten Bewegungen
Authors: Stelzner Günther , Seemann Wolfgang
Published: December 2006

Thema dieser Arbeit ist die Generierung von kinematischen Simulationsmodellen des Menschen aus experimentell ermittelten Motion‐Capture‐Daten. Ausgehend von den Absolutkoordinaten sogenanter Markerpunkte sind die Rekonstruktion der menschlichen Kinematik und die Projektion der menschlichen Bewegungsmuster auf die ermittelten Starrkörpermodelle Kernpunkt dieser Arbeit. Besonderes Augenmerk ist dabei stets auf eine möglichst einfache Kinematik gerichtet, die aber noch die wesentlichen Merkmale der menschlichen Bewegung reproduzieren kann. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An analysis of simplified muscle activation profile parameterization
Authors: Strobach Daniel , Kecskeméthy Andrés
Published: December 2006

This paper analyzes a simplified method for rough identification of muscle activation profiles of general motor tasks by means of dynamic optimization. Muscle activation profiles are parameterized with six parameters per muscle, using linear combinations of two smooth C ∞ functions closely related to the GAUSSian distribution function used in stochastics and fuzzy control. The method is applied to a simplified subsystem of the human leg consisting of pelvis, thigh shank and foot, interconnected by planar joints at hip, knee and ankle. The system comprises one antagonistic muscle pair at the knee for knee flexion and extension (vastus intermedius and biceps femoris caput brevis). To simulate the swing phase of gait, rheonomic constraints are imposed on pelvis (translation and rotation), hip (rotation) and ankle (rotation). The optimization results show that, (1) the method is suitable to map typical muscle activation time histories that are recorded via EMG, (2) the method can reduce the number of design parameters and CPU‐time consumption significantly in comparison to other parameterizations and (3) this reduction in CPU‐time consumption additionally coinncides with an improved approximation quality to the target motion. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical Simulation of the Flow in a Micro‐Axial Blood Pump
Authors: Triep Michael , Brücker Christoph , Sieß Thorsten
Published: December 2006

Computational fluid dynamics (CFD) simulations of the three‐dimensional, turbulent flow in a micro‐axial blood pump were carried out for various working conditions. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Response of Kidney Tissue to Dynamical Loading
Authors: Weinberg Kerstin
Published: December 2006

In shock‐wave lithotripsy – a medical procedure to fragment kidney stones – the patient is subjected to hypersonic waves focused at the kidney stone. Although this procedure is widely applied, the physics behind this medical treatment, in particular the question of how the injuries of the surrounding kidney tissue arise, is still under investigation. Here we contribute to the solution of this problem with large scale numerical simulations of a human kidney under shock‐wave loading.

For this purpose we developed a complex constitutive model of the bio‐mechanical kidney system. Assuming a multiplicative decomposition of the deformation gradient and adopting an internal variable formulation for the inelastic deformation the model is able to handle large deformations, time‐effects, rate‐sensitivity and material damage.

By finite element simulations we study the shock‐wave propagation into the kidney tissue and analyze the resulting stress states. Unknown material parameters are adapted and special attention is paid on the bubble expansion within the soft tissue. The numerical simulations predict localized damage in the human kidney within the focal region of the shock waves. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A contribution to the plastic behavior of cellular bone
Authors: Winter Werner
Published: December 2006

In a first approximation the inelastic behavior of cellular bone is modelled by an isotropic elastic‐plastic material. Plastic strains can deduced using a yield‐criterion and a plastic potential which depends on invariants of the stress tensor. Irreversible (plastic) volumetric strains occur. The plastic material functions can be determined in an uniaxial experiment with a Laser Extensometer. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)