Home About us Contact
|
Home About us Contact | ||
|
|
||
Dynamic Behavior (dynamic + behavior)
Selected AbstractsDynamic Behavior of an N -Metalated ,-Enaminoimine Complex , Preparation of N -Phosphanylenamine and ,-Enaminoimine DerivativesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 5 2003Alexandrine Maraval Abstract Variable-temperature NMR spectroscopy of the ,-enaminoimine complex 2 showed a dynamic process which was attributed to an internal fluxional aldimido N -zirconated ,-linear/,-bent structure. Such an internal rearrangement has been previously proposed to occur in these systems but never observed. We have prepared a variety of (N -phosphanyl-,-enamino)imine ligands using the hydrozirconation/transmetalation reaction of malonodinitrile compounds RCH(CN)2 (R = H, PPh2). In addition to their potential uses in coordination chemistry, these systems are good tools for the study of intramolecular hydrogen bonding. The X-ray crystal structure of 14 at 180 K shows an unsymmetrical system with the N(H) proton localized on one of the two chelating nitrogen atoms, consistent with the existence in solution of a low barrier proton transfer process with a double-well potential. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] A Bowl-Shaped ortho -Semiquinone Radical Anion: Quantitative Evaluation of the Dynamic Behavior of Structural and Electronic Features,ANGEWANDTE CHEMIE, Issue 36 2010Akira Ueda Dr. Elegant aufgetischt: Das erste ,schüsselförmige" o -Semichinonradikal (siehe Bild; mit einem Na+ -Ion) wurde synthetisiert und bezüglich seiner elektronischen Eigenschaften charakterisiert. Das dynamische Verhalten (konkav,konvex) wurde mit EPR- und ENDOR/TRIPLE-Messungen sowie DFT-Rechnungen ebenfalls quantitativ untersucht. [source] Conformation Analyses, Dynamic Behavior and Amide Bond Distortions of Medium-Sized Heterocycles.CHEMINFORM, Issue 24 2005Part 1. No abstract is available for this article. [source] Conformation Analyses, Dynamic Behavior, and Amide Bond Distortions of Medium-Sized Heterocycles.CHEMINFORM, Issue 24 2005Part 2. No abstract is available for this article. [source] Metal-Complex Assemblies Constructed from the Flexible Hinge-Like Ligand H2bhnq: Structural Versatility and Dynamic Behavior in the Solid StateCHEMISTRY - A EUROPEAN JOURNAL, Issue 11 2004Koichi Yamada Dr. Abstract Novel metal-complex assemblies constructed from the flexible hinge-like ligand H2bhnq (H2bhnq=2,2,-bi(3-hydroxy-1,4-naphthoquinone)) have been synthesized. The X-ray crystal structures of these compounds reveal that four types of architectures are accessible by variation of the metal ions. In copper(II) compounds 1,3, the chelating bhnq2, ions bridge copper(II) centers to form one-dimensional zigzag chains. The chains of 1,3 are arranged by hydrogen-bonding interactions and stacking interactions to produce porous structures. Cobalt(II) and zinc(II) compounds 4 and 5 form one-dimensional helical chains. In 4 and 5, the crystal packing induces spontaneous resolution of the helical chains with chiral cavities formed perpendicular to the helices. Nickel(II) compounds 6 and 7 form cyclic tetramers. The fourth architecture, a dimer (compound 8), is obtained by the reaction of zinc(II) and bhnq2, in MeOH. In these compounds, changes of the dihedral angles and the metal-coordination mode of the bhnq2, ion induce the structural versatility. The assemblies of the zigzag chains of the copper(II) compounds exhibit reversible vapochromic behavior. UV/Vis, powder X-ray diffraction, EPR, and adsorption isotherm measurements indicate that this vapochromic behavior is based on the hinge-like flexibility of the bhnq2, ion. [source] Dynamic behavior of pentacoordinate organogermanium carboxylic acids and their pyridinium saltsHETEROATOM CHEMISTRY, Issue 5 2001Yoshito Takeuchi Solution structures of some pentavalent organogermanium compounds have been investigated. Variable temperature NMR studies of these compounds revealed that concomitant Berry pseudorotation and prototropy occur, which make the two protons of the CH2 moiety nonequivalent at lower temperatures. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:451,456, 2001 [source] Dynamic behavior of the flow field in a RIM machine mixing chamberAICHE JOURNAL, Issue 6 2009Ricardo J. Santos Abstract Dynamic behavior of the flow field in a Reaction Injection Molding, RIM, machine mixing chamber, having dimensions typically used in industrial machines, is studied from dynamic velocity data of Laser Doppler Anemometry, LDA, measurements and Computational Fluid Dynamics, CFD, simulations with a 2D model. This study is based on the spectral analysis of the dynamic flow field data. The typical frequencies, in the reactor flow field, are identified and its values are related to the identified flow structures. The differences between the typical frequencies from experiments and simulations are observed and justified on the basis of the 2D representation of a 3D cylindrical geometry. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Numerical investigation of continuous processes for catalytic hydrogenation of nitrile butadiene rubberPOLYMER ENGINEERING & SCIENCE, Issue 5 2002Qinmin Pan Dynamic behavior of continuous processes was numerically investigated for the catalytic hydrogenation of nitrile butadiene rubber, based on developed models, which took into account the coupling between kinetics and mass transfer. The evolution of hydrogenation reaction trajectories in both cases were analyzed. It is proposed that the coupling behavior between the catalytic hydrogenation and mass transfer was completely determined by the ability of the catalyst in activating hydrogen, carbon-carbon double bond loading level and the relative capacity of reaction to mass transfer as well as the residence time in the reactor. Four dimensionless parameters were derived to characterize these aspects. The effects of operation conditions on the hydrogenation processes were investigated. The application of the ideal flow models to non-ideal flows was in addition discussed. It is suggested that the optimal reactor for such a hydrogenation system would be a plug flow reactor with an instantaneous well-mixing component in the inlet of it, and a reasonable approach to the proposed optimal reactor should be with the flow behavior of at least three continuous stirred tank reactors in series. Further research directions are suggested. [source] Dynamics of Ventricular Repolarization in Patients with Dilated Cardiomyopathy Versus Healthy SubjectsANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 2 2005Jose Luis Alonso M.D. Background: Patients with impaired left ventricular function have a high risk of developing ventricular arrhythmias and sudden death. Among different markers of risk, the prolongation and regional heterogeneity of repolarization are of increasing interest. However, there are limited data regarding feasibility of analyzing repolarization parameters and their dynamics in 24-hour Holter ECG recordings. Methods: Dynamic behavior of repolarization parameters was studied with a new automatic algorithm in digital 24-hour Holter recordings of 60 healthy subjects and 55 patients with idiopathic dilated cardiomyopathy (IDC). Repolarization parameters included the mean value of QT and QTc durations, QT dispersion, and peaks of QT duration and QT dispersion above prespecified thresholds. Results: In comparison to healthy subjects, patients with IDC had lower heart rate variability, longer mean QT and QTc durations, higher content of QTc peaks >500 ms, longer QT dispersion and its standard deviation, and a higher content of peaks >100 ms of QT dispersion (P < 0.01 for all comparisons). These repolarization parameters were significantly higher in IDC patients after adjustment for age, sex, and heart rate variability. The parameters of repolarization dynamics correlated with SDNN in healthy subjects but not in dilated cardiomyopathy patients. Conclusions: The automatic assessment of repolarization parameters in 24-hour digital ECG recordings is feasible and differentiates dilated cardiomyopathy patients from healthy subjects. Patients with dilated cardiomyopathy have increased QT duration, QT dispersion, and increased variability of QT dispersion reflecting variations in T-wave morphology, the factors which might predispose them to the development of arrhythmic events. [source] Natural head motion synthesis driven by acoustic prosodic featuresCOMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 3-4 2005Carlos Busso Abstract Natural head motion is important to realistic facial animation and engaging human,computer interactions. In this paper, we present a novel data-driven approach to synthesize appropriate head motion by sampling from trained hidden markov models (HMMs). First, while an actress recited a corpus specifically designed to elicit various emotions, her 3D head motion was captured and further processed to construct a head motion database that included synchronized speech information. Then, an HMM for each discrete head motion representation (derived directly from data using vector quantization) was created by using acoustic prosodic features derived from speech. Finally, first-order Markov models and interpolation techniques were used to smooth the synthesized sequence. Our comparison experiments and novel synthesis results show that synthesized head motions follow the temporal dynamic behavior of real human subjects. Copyright © 2005 John Wiley & Sons, Ltd. [source] Numerical Methods to Simulate and Visualize Detailed Crane ActivitiesCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 3 2009Shih-Chung Kang One major consideration for virtual construction is the simulation of the operation of construction equipment for a construction project. This research specifically focuses on developing a mathematical model to support the simulation and visualization of cranes, the most critical equipment in terms of project controls. This model is composed of two submodels,a kinematics model and a dynamic model. The kinematics model is to present the crane components controlled by the operators. The dynamic model is to present the dynamic behavior in suspended system (including the cable and rigging object), which cannot be controlled directly by the operators. To verify the feasibility of these methods, a computer program that simulates and visualizes detailed crane activities was developed. This program supports the real-time visualization of crane activities with high degree of reality accuracy and also, enables the detailed simulation of long-term construction projects. [source] Collapse of Reinforced Concrete Column by Vehicle ImpactCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 6 2008Hing-Ho Tsang The column slenderness ratio can be in the order of 6,9. Some of these buildings are right next to busy streets and hence continuously exposed to the potential hazard of a vehicle impacting on a column in an accident. In the early part of this study, the ultimate energy absorption capacity of a reinforced concrete column is compared to the kinetic energy embodied in the moving vehicle. The energy-absorption capacity is calculated from the force-displacement curve of the column as determined from a nonlinear static (push-over) analysis. The ultimate displacement of the column is defined at the point when the column fails to continue carrying the full gravitational loading. Results obtained from the nonlinear static analysis have been evaluated by computer simulations of the dynamic behavior of the column following the impact. Limitations in the static analysis procedure have been demonstrated. The effects of strain rate have been discussed and the sensitivity of the result to changes in the velocity function and stiffness of the impacting vehicle has also been studied. [source] Dynamic load-balancing mechanism for distributed Java applicationsCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 3 2006Violeta Felea Abstract Program environments or operating systems generally leave the decision on the allocation of program entities to the developer, offering either placement directives, or tools available through the manipulation of a graphical interface. These approaches cannot always take into account the dynamic behavior of applications, dynamicity in the execution environment or the heterogeneity of the execution platform. Transparent deployment algorithms are necessary for automizing and optimizing application distribution. The Adaptive Distributed Applications in Java (ADAJ) project deals with placement and migration of Java objects. It automatically deploys parallel Java applications on a cluster of workstations using monitoring information about the application behavior. The transparency obtained through the integration of these tools in the middleware makes such an environment easy to use and improves efficiency. Copyright © 2005 John Wiley & Sons, Ltd. [source] Live-cell analysis of mitotic spindle formation in taxol-treated cellsCYTOSKELETON, Issue 8 2008Jessica E. Hornick Abstract Taxol functions to suppress the dynamic behavior of individual microtubules, and induces multipolar mitotic spindles. However, little is known about the mechanisms by which taxol disrupts normal bipolar spindle assembly in vivo. Using live imaging of GFP-, tubulin expressing cells, we examined spindle assembly after taxol treatment. We find that as taxol-treated cells enter mitosis, there is a dramatic re-distribution of the microtubule network from the centrosomes to the cell cortex. As they align there, the cortical microtubules recruit NuMA to their embedded ends, followed by the kinesin motor HSET. These cortical microtubules then bud off to form cytasters, which fuse into multipolar spindles. Cytoplasmic dynein and dynactin do not re-localize to cortical microtubules, and disruption of dynein/dynactin interactions by over-expression of p50 "dynamitin" does not prevent cytaster formation. Taxol added well before spindle poles begin to form induces multipolarity, but taxol added after nascent spindle poles are visible,but before NEB is complete,results in bipolar spindles. Our results suggest that taxol prevents rapid transport of key components, such as NuMA, to the nascent spindle poles. The net result is loss of mitotic spindle pole cohesion, microtubule re-distribution, and cytaster formation. Cell Motil. Cytoskeleton 2008. © 2008 Wiley-Liss, Inc. [source] The contributions of microtubule stability and dynamic instability to adenovirus nuclear localization efficiencyCYTOSKELETON, Issue 9 2007James C. Warren Abstract Adenoviruses (Ads) utilize host cell microtubules to traverse the intracellular space and reach the nucleus in a highly efficient manner. Previous studies have shown that Ad infection promotes the formation of stable, posttranslationally modified microtubules by a RhoA-dependent mechanism. Ad infection also shifts key parameters of microtubule dynamic instability by a Rac1-dependent mechanism, resulting in microtubules with lower catastrophe frequencies, persistent growth phases, and a bias toward net growth compared to microtubules in uninfected cells. Until now it was unclear whether changes in RhoGTPase activity or microtubule dynamics had a direct impact on the efficiency of Ad microtubule-dependent nuclear localization. Here we have performed synchronous Ad infections and utilized confocal microscopy to analyze the individual contributions of RhoA activation, Rac1 activation, microtubule stability, dynamic behavior, and posttranslational modifications on Ad nuclear localization efficiency (NLE). We found that drug-induced suppression of microtubule dynamics impaired Ad NLE by disrupting the radial organization of the microtubule array. When the microtubule array was maintained, the suppression or enhancement of microtubule turnover did not significantly affect Ad NLE. Furthermore, RhoA activation or the formation of acetylated microtubules did not enhance Ad NLE. In contrast, active Rac1 was required for efficient Ad nuclear localization. Because Rac1 mediates persistent growth of microtubules to the lamellar regions of cells, we propose that Ad-induced activation of Rac1 enhances the ability of microtubules to "search and capture" incoming virus particles. Cell Motil. Cytoskeleton 2007. © 2007 Wiley-Liss, Inc. [source] Microtubule-dependent organization of subcortical microfilaments in the early Drosophila embryoDEVELOPMENTAL DYNAMICS, Issue 3 2007Maria Giovanna Riparbelli Abstract Dynamic alterations in the spatial organization of cytoskeletal elements constitute a prominent morphological feature of the early, syncytial stages of embryogenesis in Drosophila. Here, we describe and characterize the dynamic behavior of cytoplasmic, subcortical microfilaments, which form a series of nucleus-associated structures, at different phases of the simultaneous nuclear division cycles characteristic of early Drosophila embryos. Remodeling of the cytoplasmic microfilament arrays takes place in parallel to the established cyclic reorganization of cortical microfilament structures. We provide evidence that the cortical and subcortical microfilament populations organize independently of each other, and in response to distinct instructive cues. Specifically, formation of subcortical microfilament structures appears to rely on, and spatially mirror, the organization of polarized microtubule arrays, while cortical microfilament restructuring constitutes a centrosome-dependent process. Genetic analysis identifies a requirement for SCAR, a key mediator of Arp2/3-based microfilament dynamics, in organization of subcortical microfilament structures. Developmental Dynamics 236:662,670, 2007. © 2007 Wiley-Liss, Inc. [source] Non-linear behavior of mass concrete in three-dimensional problems using a smeared crack approachEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 3 2005H. Mirzabozorg Abstract A smeared crack approach has been proposed to model the static and dynamic behavior of mass concrete in three-dimensional space. The proposed model simulates the tensile fracture on the mass concrete and contains pre-softening behavior, softening initiation, fracture energy conservation and strain rate effects under dynamic loads. The validity of the proposed model has been checked using the available experimental results under static and dynamic loads. The direct and indirect displacement control algorithms have been employed under incremental increasing static loads. It was found that the proposed model gives excellent results and crack profiles when compared with the available data under static loads. The Koyna Dam in India has been used to verify the dynamic behavior of the proposed model. It was found that the resulting crack profiles were in good agreement with the available experimental results. Finally, the Morrow Point Dam was analyzed, including the dam,reservoir interaction effects, to consider its non-linear seismic behavior. It was found that the resulting crack profiles were in good agreement with the contour of maximum principal stresses and no numerical instability occurred during the analysis. Copyright © 2004 John Wiley & Sons, Ltd. [source] Optimal design of added viscoelastic dampers and supporting bracesEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 4 2004Ji-Hun Park Abstract This paper presents a simultaneous optimization procedure for both viscoelastic dampers (VEDs) and supporting braces installed in a structure. The effect of supporting braces on the control efficiency of VEDs is also investigated. To apply a general gradient-based optimization algorithm, closed-form expressions for the gradients of objective function and constraints are derived. Also, the constraint on the dynamic behavior of a structure is embedded in the gradient computation procedure to reduce the number of variables in the optimization. From numerical analysis of an example structure, it was found that when sufficient stiffness cannot be provided for the supporting braces, the flexibility of the brace should be taken into account in the design of the VED to achieve the desired performance of the structure. It was also observed that, as a result of the proposed optimization process, the size of the supporting brace could be reduced while the additional VED size (to compensate for the loss of the control effect) was insignificant. Copyright © 2003 John Wiley & Sons, Ltd. [source] Fundamental characteristics and 3D electromagnetic analysis for magnetic levitation transporter using YBCO superconductorsELECTRICAL ENGINEERING IN JAPAN, Issue 2 2007Hiroshi Ueda Abstract A magnetic levitation device with two-dimensional movement, the so-called "levitating X-Y transporter," has been developed. In order to develop a working levitating X-Y transporter, it is necessary to clarify the levitation characteristics, such as the lift force, levitation height, and stability against mechanical disturbances. In this paper, we examine the lift and the restoring force experimentally and propose a new simulation program based on the three-dimensional hybrid finite and boundary element method to analyze the dynamic behavior of electromagnetic characteristics of YBCO bulk. Using the numerical simulation and experiments, we investigated a suitable arrangement of permanent magnets to enhance the levitation characteristics. We also designed a levitating transporter which can carry a load of 200 kg with a gap of 16 mm. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(2): 44,54, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20220 [source] Transport behavior of 3,3,-dichlorobenzidine in a freshwater estuaryENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2003Marianne C. Nyman Abstract Like many hydrophobic organic compounds, 3,3,-dichlorobenzidine (DCB) partitions preferentially to (sediment) particles in lake systems. As such, the behavior of DCB in these systems is substantially affected by the movement of sediments. A field investigation of DCB distribution in sediments of Lake Macatawa (Holland, MI, USA) was initiated. The pattern of DCB distribution within the lake was found to display an oscillatory pattern that was consistent with a wind-driven mechanism of sediment transport. Numerical modeling of seiching behavior supported the hypothesized importance of this mechanism of sediment transport and redistribution. The dynamic behavior of sediment-associated DCB within Lake Macatawa seems to be strongly influenced by phenomena that are common to many freshwater estuaries. As such, the behavior of this system is expected to represent a reasonable model of the dynamic behavior of hydrophobic contaminants in other freshwater estuaries. [source] Energy functions for FACTS devices with an energy-storage systemEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 5 2007V. Azbe Abstract An energy-storage system (ESS) can provide additional capabilities for FACTS devices in dynamic power-flow control, and in this way improve electric-power system stability. In order to assess their influence on the system's dynamic behavior or to determinate the device's control strategy using direct methods, proper energy functions for these devices are needed. In this paper the energy functions for the whole spectrum of FACTS devices with an ESS have been developed. For each of the devices various energy functions were proposed according to the control strategy applied. The energy functions were constructed as additional terms that can be added to any existing structure-preserving energy function (SPEF). Tests within a single-machine infinite-bus system proved the correctness of the proposed energy functions. The application of new energy functions was demonstrated on the problem of transient-stability assessment. Copyright © 2006 John Wiley & Sons, Ltd. [source] Schizosaccharomyces pombe homolog of Survivin, Bir1p, exhibits a novel dynamic behavior at the spindle mid-zoneGENES TO CELLS, Issue 7 2006Srividya Rajagopalan Members of the BIR-domain containing Survivin family of proteins have been identified in a variety of eukaryotes and are known to play important roles in the regulation of mitosis. The Schizosaccharomyces pombe homolog of Survivin, Bir1p, is essential for chromosome condensation and spindle elongation and integrity. Bir1p, a nuclear protein, resides at the kinetochores in metaphase and anaphase A and spreads to the spindle mid-zone in anaphase B. Here we show that this relocation requires Cdk (Cyclin dependent kinase) inactivation and intact microtubules. With the aid of a kinesin mutant, klp5,, we also show that completion of anaphase A is vital for effecting Bir1p re-location to the spindle mid-zone. Although minimal exchange of Bir1p sub-units occurs between the spindle and the nucleoplasm, the protein redistributes laterally within the mid-zone region. Bir1p dynamics therefore significantly differs from that of tubulin on an anaphase B spindle, which is loaded at the plus ends of growing microtubules and shows no lateral redistribution within the spindle. Thus, Bir1p, and possibly its associated proteins, might organize a dynamic mid-zone region that helps spindle elongation and maintenance. [source] An experimental investigation on spreading of droplets with evaporation and nucleationHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 1 2009Gui Lu Abstract An experimental investigation was conducted to visually observe the dynamic characteristics of water droplets with evaporation and nucleation on stainless steel and polished silicon surfaces. The water droplet diameter, contact area, and spreading speed were measured using a high-speed CCD camera at surface temperatures ranging from 110°C to 190°C, and a model was proposed to describe the dynamic behavior of droplet spreading. The spreading of water droplets under evaporation and nucleate boiling is highly dependent on the dynamic bubble behavior in the droplets, particularly bubble volume, bubble interaction, as well as the surface properties and temperature. Water droplets were easiest to spread at the surface temperature of 130 °C, and the spreading tendency increased with increasing surface coarseness. © 2008 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20231 [source] Towards a comprehensive computational model for the respiratory system,INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 7 2010Wolfgang A. Wall Abstract This paper is concerned with computational modeling of the respiratory system against the background of acute lung diseases and mechanical ventilation. Conceptually, we divide the lung into two major subsystems, namely the conducting airways and the respiratory zone represented by lung parenchyma. Owing to their respective complexity, both parts are themselves out of range for a direct numerical simulation resolving all relevant length scales. Therefore, we develop detailed individual models for parts of the subsystems as a basis for novel multi-scale approaches taking into account the unresolved parts appropriately. In the tracheobronchial region, CT-based geometries up to a maximum of approximately seven generations are employed in fluid,structure interaction simulations, considering not only airway wall deformability but also the influence of surrounding lung tissue. Physiological outflow boundary conditions are derived by considering the impedance of the unresolved parts of the lung in a fully coupled 3D-1D approach. In the respiratory zone, an ensemble of alveoli representing a single ventilatory unit is modeled considering not only soft tissue behavior but also the influence of the covering surfactant film. Novel nested multi-scale procedures are then employed to simulate the dynamic behavior of lung parenchyma as a whole and local alveolar ensembles simultaneously without resolving the alveolar micro-structure completely. Copyright © 2010 John Wiley & Sons, Ltd. [source] FOIST: Fluid,object interaction subcomputation techniqueINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 9 2009V. Udoewa Abstract Our target is to develop computational techniques for studying aerodynamic interactions between multiple objects. The computational challenge is to predict the dynamic behavior and path of the object, so that separation (the process of objects relatively falling or moving away from each other) is safe and effective. This is a very complex problem because it has an unsteady, 3D nature and requires the solution of complex equations that govern the fluid dynamics (FD) of the object and the aircraft together, with their relative positions changing in time. Large-scale 3D FD simulations require a high computational cost. Not only must one solve the time-dependent Navier,Stokes equations governing the fluid flow, but also one must handle the equations of motion of the object as well as the treatment of the moving domain usually treated as a type of pseudo-solid. These costs include mesh update methods, distortion-limiting techniques, and remeshing and projection tactics. To save computational costs, point force calculations have been performed in the past. This paper presents a hybrid between full mesh-moving simulations and the point force calculation. This mesh-moving alternative is called FOIST: fluid,object subcomputation interaction technique. Copyright © 2009 John Wiley & Sons, Ltd. [source] Spiral waves in bio-inspired oscillatory dissipative mediaINTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 5-6 2008Fernando Corinto Abstract Spiral waves are the most universal form of patterns arising in dissipative media of oscillatory and excitable nature. By focusing on oscillatory networks, whose cells admit of a Lur'e description and are linearly connected through weak couplings, the occurrence of spiral waves has been studied. In particular, the global dynamic behavior of such networks is investigated through the phase deviation equation obtained by the joint application of the harmonic balance method and Malkin's theorem. Furthermore, a simple condition for verifying the occurrence of spiral waves is provided. Copyright © 2008 John Wiley & Sons, Ltd. [source] On the dynamics of default reasoningINTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 12 2002Grigoris Antoniou Default logic is a prominent rigorous method for reasoning with incomplete information based on assumptions. It is a static reasoning approach, in the sense that it doesn't reason about changes and their consequences. On the other hand, its nonmonotonic behavior appears when changes to a default theory are made. This paper studies the dynamic behavior of default logic in the face of changes. We consider the operations of contraction and revision, present several solutions to these problems, and study their properties. © 2002 Wiley Periodicals, Inc. [source] Robust impedance control of a hydraulic suspension systemINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 8 2010Mohammad Mehdi FatehArticle first published online: 2 JUN 200 Abstract A novel robust impedance control approach is developed to control dynamic behavior of a vehicle subject to road disturbances. This behavior is predetermined as an impedance rule to achieve passenger comfort and vehicle handling by the use of a hydraulically actuated suspension system. Impedance control law is simple, free of model and efficient to apply for a broad range of road conditions. Moreover, it relates comfort to handling. This control approach can provide a desired comfort when passing a bump, and both desired comfort and handling after passing a bump. Robust position and force controls are used to implement the robust impedance control with the presence of uncertainties. A transformed proportional,integral,derivative control is proposed to perform the robust control. The system stability is analyzed and analytical results are confirmed by simulations. A quarter-car model of suspension system and a nonlinear model of hydraulic actuator are used to simulate the control system. Copyright © 2009 John Wiley & Sons, Ltd. [source] Pirouetting in chiral [2]catenanes,ISRAEL JOURNAL OF CHEMISTRY, Issue 2 2007Seogshin Kang One of the best known classes of mechanically interlocked molecules is the category of [2]catenanes, which exhibit donor-acceptor interactions between the 1,5-dioxynaphthalene (DNP) units in a crown ether and the bipyridinium units in the tetracationic cyclophane, cyclobis(paraquat- p -phenylene) (CBPQT4+). In order to gain an in-depth understanding and appreciation of the stereochemistry and dynamic behavior of these [2]catenanes, chiral analogues,having both the DNP ring, which is capable of displaying planar chirality, and the axially chiral binaphthol (BINAP) moiety (as both enantiomers and as the racemic modification), in a crown ether, in addition to the CBPQT4+ cyclophane,have been synthesized using a template-directed protocol. Dynamic 1H NMR spectroscopy shows that (i) the presence of immutable axial chirality, arising from the BINAP moiety in the crown ether component, leads to no induction of diastereoselectivity,the chiral catenanes exist as a mixture of diastereoisomers in solution at low temperatures in the approximate ratio of 1:1, (ii) the barrier (,GcD,) to the interconversion between these two diastereoisomers is 7.9 ± 0.1 kcal mol,1 at 171 K, and (iii) no induction of diastereoselectivity is observed upon the addition of a chiral solvating agent to the chrial catenanes. The pattern of behavior in the variable temperature 1H NMR spectra and the low ,TGcD, value indicates that the dynamic process involving the interconversion between these two diastereoisomers is one of a pirouetting nature. Of the four possible diastereoisomers, only two, (R)-(pR/pS) or (S)-(pR/pS), are shown to exist in solution. [source] The dynamic behavior of magnetic colloids in suspensionJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2007Tina Autenrieth The dynamic behavior of magnetic colloidal particles in suspension is investigated. The particles of the core,shell colloid consist of a cobalt ferrite core embedded in a silica shell and are stabilized by surface charges. As the suspension is strongly opaque to visible light, it can not be probed by dynamic light scattering techniques as a result of strong multiple scattering as well as absorption effects. Therefore, the static and dynamic behavior is probed with small-angle X-ray scattering and X-ray photon correlation spectroscopy (XPCS), respectively. Using XPCS, we are able to study the diffusion coefficient of an opaque colloidal system as a function of the scattering vector. In this paper, we report on the behavior of the colloidal system in the absence of an external magnetic field, meaning that the magnetic moments of the particles are oriented randomly. We find no evidence for magnetic interactions in the static data, while the dynamic XPCS data deviate very significantly from the predictions of model calculations. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||