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Dynamic Simulations (dynamic + simulation)
Kinds of Dynamic Simulations Selected AbstractsA Co-Simulation Approach for the 3D Dynamic Simulation of Vehicles Considering Sloshing in Cargo and Fuel TanksPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2009Florian Fleissner The sloshing of liquids in cargo and fuel tanks mounted on vehicles can have a significant influence on the vehicle's driving dynamics and stability. To evaluate and optimize the quality of tank designs, we propose a co-simulation approach that consists of a coupled multibody system simulation for the vehicle and a Discrete Element Method and Smoothed Particle Hydrodynamics simulation for the sloshing cargo. This approach is beneficial especially for the simulation of fluid cargos, as Smoothed Particle Hydrodynamics does not require additional models to track and reconstruct free fluid surfaces. By means of dynamic 3D simulations of a double lane change maneuvers we compare the two different cargo models and demonstrate the viability of the co-simulation approach. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Dynamic Simulation and Control of an MTBE Catalytic Distillation ColumnASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3-4 2000H. Lin A dynamic model of an MTBE (methyl tert butyl ether) catalytic distillation column was developed using the SpeedUp simulation package. Experimental kinetic rate data, rigorous thermodynamics, vapour-liquid nonidealities and tray hydraulics were incorporated in the simulation. The steady state results from the dynamic model were compared with the steady state results from a steady state model developed using the AspenPlus simulation package. The steady state results from the two simulations were in perfect agreement with each other. Open hop step tests were performed on the dynamic model of this process and the process model indicated a non-linear, self-regulating behaviour and did not exhibit any multiplicities. Multiloop linear control systems were designed and PI, PID and Dynamic Matrix Control (DMC) controllers were tested on the simulation for load disturbances and setpoint changes. All controllers performed adequately; the DMC controller consistently resulted in better dynamic control performance than the other two controllers. [source] Dynamic simulation of backdraft phenomena in a townhouse building fireHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 3 2008Shih-Cheng Wang Abstract A backdraft is a unique and extremely dangerous fire phenomenon in buildings with limited ventilation. Backdraft can generate the powerful fire and heavy smoke that hinders firefighter rescues and those escaping the fire. This study investigates a deflagration fire and smoke spread in a townhouse fire that occurred in Taiwan. The fire is reconstructed using the CFAST (ver. 6.0.10) zone model, FDS (ver. 4.0.7) field model, and full-scale fire tests for motorcycles. Computational results reasonably agree qualitatively with the post-accident reports. Simulation analysis for backdraft phenomena demonstrated that window size in the limited-ventilation compartment fire influenced smoke leaking from vents, deflagration induction time, and fire intensity from a new opening. © 2008 Wiley Periodicals, Inc. Heat Trans Asian Res, 37(3): 153,164, 2008; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/htj.20196 [source] Dynamic simulation and control of a paper machine wet endTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2001Eddy F. Yap Abstract A good simulation model for paper machines can be used to identify deficiencies in the design, bottlenecks during operation, and regions of poor control. It also allows users to test their hypotheses and innovations without potentially causing major upsets and reducing throughput. In this work, a dynamic model of the wet end system has been developed using the IDEASTM platform, describing the distribution of fines, fillers and fibres throughout the system. The model was then tested at steady state with mill data for the low-ash and high-ash production grades, and the results show that over 70% of the predicted values had only 5% deviation. The dynamic simulation was also used to show that the retention aid controller would react in the wrong direction due to changes in the wire pit consistency and the stock ratio would cause major changes in stream compositions and consistencies of the wet end. Un bon modèle de simulation des presses de papier peut en effet ,tre utile pour déterminer les failles dans la conception, les goulots d'éranglement en cours d'opération et les régions mal régulées. De m,me, il permet aux utilisateurs de tester leurs hypothèses et innovations sans risquer de causer des problèmes majeurs ou de réquire la capacité. Dans ce travail, un modèle dynamique du système à fraction humide a été mis au point à l'aide de la plate-forme IDEASTM, décrivant la distribution des fines, des agents de remplissage et des fibres dans le système. Ce modèle a ensuite été testé à l'état permanent avec les données d'une papeterie pour des qualités de papier à faibles et fortes teneurs en cendres et les résultats montrent que plus de 70% des valeurs prédites n'avaient qu'un écart de 5%. La simultation dynamique a montré que le régulateur d'aide à la rétention réagirait dans la mauvaise direction à cause de changements dans la consistance sur la toile et que le taux d'approvisionnement entra,nerait d'importants changements dans les compositions et consistances des courants de la fraction humide. [source] Dynamic simulation of kinetics, heat and mass transfer during hydrogen sorption by LaNi5ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2010Dr Tarek Moustafa Abstract A two-dimensional transient heat and mass transfer models have been developed to investigate the dynamic phenomena of hydrogen absorption and desorption in metal hydride bed. LaNi5 has been chosen as the alloy used for hydrogen storage. The numerical simulation has been conducted to simulate the time,space evolution of temperature, fractional conversion, hydrogen pressure and velocity, in addition to metal density. A correlation for the volumetric reaction rate has been deduced. Also, comparisons have been done between various bed geometries and their influence on the average hydrogen desorbed mass. The simulation results showed that heat transfer controls the overall rate of absorption and desorption processes, and because the driving force for the hydrogen flow is the axial pressure difference; the challenge to get optimum bed geometry is in compromising between heat transfer and pressure drop limitations. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Analysis and control of heteroazeotropic batch distillationAICHE JOURNAL, Issue 4 2005S. Skouras Abstract The separation of close-boiling and azeotropic mixtures by heterogeneous azeotropic distillation is addressed in batch columns. Both a common rectifier and a multivessel batch column are considered. Theoretical and graphical analyses of the process are presented for both column configurations and different separation strategies are presented. A simple control scheme is proposed for the practical operation of the columns, the implementation of different separation strategies and the realization of the final results. Dynamic simulations for mixtures classified under Serafimov's topological classes 2.0-2b and 3.1-2 verify the theoretical findings. The results show that heteroazeotropic batch distillation exhibits substantial flexibility. The column profile can be totally restored during the process and lie in regions different from those of the initial feed. The still path can cross distillation boundaries and the still product does not have to be the stable node of the feed region. Such results cannot be obtained by homogeneous azeotropic batch distillation. © 2005 American Institute of Chemical Engineers AIChE J, 2005 [source] Impulse-based dynamic simulation in linear timeCOMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 4-5 2007Jan Bender Abstract This paper describes an impulse-based dynamic simulation method for articulated bodies which has a linear time complexity. Existing linear-time methods are either based on a reduced-coordinate formulation or on Lagrange multipliers. The impulse-based simulation has advantages over these well-known methods. Unlike reduced-coordinate methods, it handles nonholonomic constraints like velocity-dependent ones and is very easy to implement. In contrast to Lagrange multiplier methods the impulse-based approach has no drift problem and an additional stabilisation is not necessary. The presented method computes a simulation step in O(n) time for acyclic multi-body systems containing equality constraints. Closed kinematic chains can be handled by dividing the model into different acyclic parts. Each of these parts is solved independently from each other. The dependencies between the single parts are solved by an iterative method. In the same way inequality constraints can be integrated in the simulation process in order to handle collisions and permanent contacts with dynamic and static friction. Copyright © 2007 John Wiley & Sons, Ltd. [source] Interactive soft-touch dynamic deformationsCOMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 3 2007Hui Chen Abstract It is crucial for the users to touch, grasp and manipulate the interested objects through our sense of touch in many interactive applications, such as on-line computer games, interactive cartoon design, and virtual prototyping. In this paper, we propose an interactive haptic deformation approach which incorporates the dynamic simulation of mass,spring systems and flexible control of free-form deformation in the touch-enabled soft-object deformation. Through distributing mass, spring and damping coefficients of the object to the bounded Bezier volume lattice, the deformation of the object related to the haptic avatar follows the physical laws and has high working rate. Both homogenous and inhomogenous materials are simulated. The anchor nodes of haptic input are specified to create amazing special effects during the interactive haptic deformation. Interactive haptic deformations of three-type tropic fishes, Angel, Demekin, and GuppyBlueGrass, have been experimented to simulate vivid fish swimming processes in the virtual ocean scene. Our proposed approach provides touch-enabled input and efficient performance in the flexible deforming controls, letting the objects move in a dynamic, cartoon-style deforming manner. Copyright © 2007 John Wiley & Sons, Ltd. [source] The Dow Chemical Project: Creating a web-based interface to a dynamic simulationCOMPUTER APPLICATIONS IN ENGINEERING EDUCATION, Issue 4 2005K. Kuriyan Abstract In this study we present a Web-based interface to a dynamic simulation. The simulation is based on an emulsion polymerization process operated by the Dow Chemical Company. We also describe the software architecture that allows simulation updates to be transmitted dynamically across a network, from a server-based simulation to a Web-based client. © 2005 Wiley Periodicals, Inc. Comput Appl Eng Educ 13: 250,256, 2005; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20049 [source] A study on thermal conductivity of a quasi-ordered liquid layer on a solid substrateHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 7 2007Xiao-Yan Shi Abstract In the present paper, a study on thermal conductivity of a quasi-ordered liquid layer on a solid surface was performed by molecular dynamic simulation. Results showed that the motion of the molecules and their radial distribution function in the quasi-ordered liquid layer were similar to those of solid molecules. By using the Green,Kubo formula, the thermal conductivity of the layer was calculated. It was found that it increased with the increase of the parameters of ordering. The size effect and the influence of the boundary condition were also discussed. © 2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 36(7): 429,434, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20171 [source] Digital human modeling and workplace evaluation: Using an automobile assembly task as an exampleHUMAN FACTORS AND ERGONOMICS IN MANUFACTURING & SERVICE INDUSTRIES, Issue 5 2007Shao-Wen Chang This study proposes a method of conducting workplace evaluations in the digital environment for the prevention of work-related musculoskeletal disorders. For visual presentation, we apply a digital human modeling system to the workplace virtual dynamic simulation. Then, we use captured workplace motion data for ergonomics evaluation, including biomechanics analysis and posture analysis. By integrating dynamic simulation and ergonomics evaluation, it enables the system designer to visualize and improve workplace design in the digital space. The method has been applied to evaluate automobile assembly tasks and some ergonomic improvements have been implemented.f© 2007 Wiley Periodicals, Inc. [source] Fluid dynamic numerical simulation coupled with heat transfer and reaction in the tubular reactor of industrial cracking furnacesINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 4 2010Chufu Li Abstract The thermal cracking furnace is the heart of the ethylene production process in a petrochemical plant. This paper presents a comprehensive mathematical model containing equations for mass, momentum and heat transfer combined with Kumar molecular kinetic model to describe dynamic behaviors of fluid flow, heat transfer and reaction in the tubular reactor of thermal cracking furnaces. The ,flow-reaction' decomposition strategy is adopted to solve the complex model for implementing the fluid dynamic simulation coupled with heat transfer and reaction in the tubular reactor by a conventional procedure. The proposed mathematical model and the decomposition algorithm are successfully applied to the fluid dynamic simulation in the tubular reactor of a millisecond industrial cracking furnace. The results of dynamic simulation reveal the various transient behaviors of fluid flow, temperature change and species content variation in the tubular reactor under the step disturbance of inlet feedrate. Finally, the performance of the decomposition algorithm is also investigated. Copyright © 2009 John Wiley & Sons, Ltd. [source] Principles of Fusion of Inertial Navigation and Dynamic VisionJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 1 2004Stevica Graovac The possibility of fusion of navigation data obtained by two separate navigation systems (strap-down inertial one and dynamic vision based one) is considered in this paper. The attention is primarily focused on principles of validation of separate estimates before their use in a combined algorithm. The inertial navigation system (INS) based on sensors of medium level quality has been analyzed on one side, while a visual navigation method is based on the analysis of a sequence of images of ground landmarks produced by an on-board TV camera. The accuracy of INS estimations is being improved continuously by optimal estimation of a flying object's angular orientation while the visual navigation system offers discrete corrections during the intervals of presence of landmarks inside the camera's field of view. The concept is illustrated by dynamic simulation of a realistic flight scenario. © 2004 Wiley Periodicals, Inc. [source] Generalization and numerical investigation of QMOMAICHE JOURNAL, Issue 1 2007R. Grosch Abstract A generalized framework is developed for the quadrature method of moments (QMOM), which is a solution method for population balance models. It further evaluates the applicability of this method to industrial suspension crystallization processes. The framework is based on the concepts of generalized moments and coordinate transformations, which have been used already in earlier solution approaches. It is shown how existing approaches to QMOM are derived from the suggested unified framework. Thus, similarities and differences between the various QMOM methods are uncovered. Further, potential error sources involved in the different approaches to QMOM are discussed and assessed by means of a series of test cases. The test cases are selected to be challenging. The error in the QMOM solution is evaluated by comparison to an adaptive, error controlled solution of the population balance. The behavior of a range of different QMOM formulations is analyzed by means of numerical quadrature, dynamic simulation, as well as numerical continuation and bifurcation analysis. As a result of this detailed analysis, some general limitations of the method are detected and guidelines for its application are developed. This article is limited to lumped population balance models with one internal coordinate. © 2006 American Institute of Chemical Engineers AIChE J, 2007 [source] Fluid dynamic simulation of O3 decomposition in a bubbling fluidized bedAICHE JOURNAL, Issue 11 2003Madhava Syamlal Recent advances in dense, multiphase, computational fluid dynamics (CFD) have allowed accurate simulation of the gas and particle motion in bubbling and circulating fluidized beds. Since fluidized-bed reactors are used for many chemical processes, a simulation must also be able to accurately couple chemical reactions to bed hydrodynamics. The catalytic decomposition of ozone (O3) often has been used to study experimentally the contacting behavior of catalytic reactors. Simulations of laboratory-scale experiments of premixed O3 decomposition in a bubbling fluidized bed using the multiphase CFD code MFIX were conducted. The grid-independent results are in very good agreement with reported experimental data on total conversion over a range of fluidization velocities and initial bed heights. This confirms the ability of multiphase hydrodynamic models to capture quantitatively the effect of hydrodynamics on chemical reactions in a bubbling fluidized bed. [source] A heuristic approach of calculating spray water flux needed to avert fire-induced runaway reactions,,PROCESS SAFETY PROGRESS, Issue 3 2006BChE (Honors), Dilip K. Das BSc (Honors), MSChE In general all reactions have some heat effects. When the ability of the equipment to remove the heat is exceeded by the heat generated by a reaction, a hazardous situation called a runaway reaction may take place. Sometimes the exothermicity of runaway reactions is so high that the size of an emergency vent becomes impractical to install. A water spray system can sometimes be used to avert a fire-induced runaway reaction. Because the water spray system has a finite activation time, insulation helps to prolong the time required to reach the decomposition temperature. This article concludes that the required water flux to avert the fire-induced runaway reaction may be conservatively estimated by adding the water flux necessary to maintain an unbroken water film on the external surface of the equipment and the water flux necessary to absorb the fire heat after allowing for the splash loss and the in-flight loss. When adequate spray water is used, the metal temperature of the insulation jacket cannot theoretically exceed the boiling point of water thereby ensuring the avoidance of fire-induced runaway reactions whose adjusted onset decomposition temperature exceeds 100 ° C. Fire-induced runaway reactions with lower onset temperature can also be avoided depending on the initial temperature of the contents, mass of the contents and equipment, insulation thickness, and fire duration, for example, but a detailed calculation including dynamic simulation is necessary and the burden of proof lies with the designer. The reliability of the spray water system must be maintained high to include its credit as an environmental factor defined according to NFPA 30 to avoid the fire-induced runaway reaction as a scenario. Although API RP 521 does not allow any credit for sprinkler water, it allows credit, unlike NFPA 30, for insulation thickness and thus a runaway reaction can be avoided by using insulation alone according to API RP 521. © 2006 American Institute of Chemical Engineers Process Saf Prog, 2006 [source] Dynamisch-thermisches CFD-Verfahren mit angepaßter RegelungsmethodeBAUPHYSIK, Issue 1 2007Tobias Zitzmann Dipl.-Ing. (FH) Zur Reduktion des Zeitaufwands von dynamisch-thermischen Langzeitsimulationen mit CFD-Programmen wurde in kürzlich veröffentlichten Studien eine neuartige Freeze-Flow Methode vorgestellt. Diese basiert auf der periodischen Umschaltung zwischen der volldynamischen Lösung aller Gleichungen und der ausschließlichen Lösung der Enthalpie-Gleichungen (eingefrorene Luftströmung). Dieser Artikel beschreibt eine neue, angepaßte Regelung für diese Umschaltung, wodurch eine zusätzliche Reduzierung der Simulationszeit erzielt wird. In Tests an Modellen für die mechanische und freie Lüftung sowie der freien Konvektion im geschlossenen Raum für feste und zeitveränderliche thermische Randbedingungen wurde im Vergleich zur ununterbrochenen volldynamischen Simulation eine Simulationszeiteinsparung von bis zu 93% erreicht. Dynamic thermal CFD approach using an adaptive control method. Previously published studies have presented a novel freeze-flow method for reducing CPU requirements of long-term dynamic thermal simulations using CFD programs. This works by intermittently switching between solution of the full dynamic equations and solution of the enthalpy equation only (frozen flow). This paper describes a new automated control method for this switching strategy and shows an additional decrease in simulation time. In tests with models for mechanical and natural ventilation and for free convection in a sealed room with constant and time varying thermal boundary conditions, a simulation time reduction of up to 93% was achieved when compared to a continuous fully dynamic simulation. [source] Design of (Gd-DO3A)n -polydiamidopropanoyl-peptide nucleic acid- D(Cys-Ser-Lys-Cys) magnetic resonance contrast agentsBIOPOLYMERS, Issue 12 2008Nariman V. Amirkhanov Abstract We hypothesized that chelating Gd(III) to 1,4,7-tris(carboxymethylaza)cyclododecane-10-azaacetylamide (DO3A) on peptide nucleic acid (PNA) hybridization probes would provide a magnetic resonance genetic imaging agent capable of hybridization to a specific mRNA. Because of the low sensitivity of Gd(III) as an magnetic resonance imaging (MRI) contrast agent, a single Gd-DO3A complex per PNA hybridization agent could not provide enough contrast for detection of cancer gene mRNAs, even at thousands of mRNA copies per cell. To increase the Gd(III) shift intensity of MRI genetic imaging agents, we extended a novel DO3An -polydiamidopropanoyl (PDAPm) dendrimer, up to n = 16, from the N-terminus of KRAS PNA hybridization agents by solid phase synthesis. A C-terminal D(Cys-Ser-Lys-Cys) cyclized peptide analog of insulin-like growth factor 1 (IGF1) was included to enable receptor-mediated cellular uptake. Molecular dynamic simulation of the (Gd-DO3A-AEEA)16 -PDAP4 -AEEA2 - KRAS PNA-AEEA- D(Cys-Ser-Lys-Cys) genetic imaging nanoparticles in explicit water yielded a pair correlation function similar to that of PAMAM dendrimers, and a predicted structure in which the PDAP dendron did not sequester the PNA. Thermal melting measurements indicated that the size of the PDAP dendron included in the (DO3A-AEEA)n -PDAPm -AEEA2 - KRAS PNA-AEEA- D(Cys-Ser-Lys-Cys) probes (up to 16 Gd(III) cations per PNA) did not depress the melting temperatures (Tm) of the complementary PNA/RNA hybrid duplexes. The Gd(III) dendrimer PNA genetic imaging agents in phantom solutions displayed significantly greater T1 relaxivity per probe (r1 = 30.64 ± 2.68 mM,1 s,1 for n = 2, r1 = 153.84 ± 11.28 mM,1 s,1 for n = 8) than Gd-DTPA (r1 = 10.35 ± 0.37 mM,1 s,1), but less than that of (Gd-DO3A)32 -PAMAM dendrimer (r1 = 771.84 ± 20.48 mM,1 s,1) (P < 0.05). Higher generations of PDAP dendrimers with 32 or more Gd-DO3A residues attached to PNA- D(Cys-Ser-Lys-Cys) genetic imaging agents might provide greater contrast for more sensitive detection. © 2008 Wiley Periodicals, Inc. Biopolymers 89: 1061,1076, 2008. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Numerical Simulation of Absorbing CO2 with Ionic LiquidsCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 10 2010X. Wang Abstract Although separating CO2 from flue gas with ionic liquids has been regarded as a new and effective method, the mass transfer properties of CO2 absorption in these solvents have not been researched. In this paper, a coupled computational fluid dynamic (CFD) model and population balance model (PBM) was applied to study the mass transfer properties for capturing CO2 with ionic liquids solvents. The numerical simulation was performed using the Fluent code. Considering the unique properties of ionic liquids, the Eulerian-Eulerian two-flow model with a new drag coefficient correlation was employed for the gas-liquid fluid dynamic simulation. The gas holdup, interfacial area, and bubble size distribution in the bubble column reactor were predicted. The mass transfer coefficients were estimated with Higbie's penetration model. Furthermore, the velocity field and pressure field in the reactor were also predicted in this paper. [source] Approximating character biomechanics with real-time weighted inverse kinematicsCOMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 4-5 2007Michael Meredith Abstract In this paper we show how the expensive, offline dynamic simulations of character motions can be approximated using the cheaper weighted inverse kinematics (WIK)-based approach. We first show how a dynamics-based approach can be used to produce a motion that is representative of a real target actor using the motion of a different source actor and the biomechanics of the target actor. This is compared against a process that uses WIK to achieve the same motion mapping goal without direct biomechanical input. The parallels between the results of the two approaches are described and further reasoned from a mathematical perspective. Thus we demonstrate how character biomechanics can be approximated with real-time WIK. Copyright © 2007 John Wiley & Sons, Ltd. [source] Planetary gear set and automatic transmission simulation for machine design courses,COMPUTER APPLICATIONS IN ENGINEERING EDUCATION, Issue 3 2003Scott T. Dennis Abstract Due to their unique ability to provide a variety of gear ratios in a very compact space, planetary gear systems are seen in many applications from small powered screw drivers to automobile automatic transmissions. The versatile planetary gear device is often studied as part of an undergraduate mechanical engineering program. Textbook presentations typically illustrate how the different planetary gear components are connected. Understanding of the operation of the planetary gear set can be enhanced using actual hardware or simulations that show how the components move relative to each other. The Department of Engineering Mechanics at the United States Air Force Academy has developed a computer simulation of the planetary gear set and the Chrysler 42LE automatic transmission. Called "PG-Sim," the dynamic simulations complement a static textbook presentation. PG-Sim is used in several of our courses and assessment data clearly indicates students' appreciation of its visual and interactive features. In this paper, we present an overview of PG-Sim and then describe how the simulation courseware facilitates understanding of the planetary gear system. © 2003 Wiley Periodicals, Inc. Comput Appl Eng Educ 11: 144,155, 2003; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.10045 [source] Tactics-Based Behavioural Planning for Goal-Driven Rigid Body ControlCOMPUTER GRAPHICS FORUM, Issue 8 2009Stefan Zickler Computer Graphics [I.3.7]: Animation-Artificial Intelligence; [I.2.8]: Plan execution, formation, and generation; Computer Graphics [I.3.5]: Physically based modelling Abstract Controlling rigid body dynamic simulations can pose a difficult challenge when constraints exist on the bodies' goal states and the sequence of intermediate states in the resulting animation. Manually adjusting individual rigid body control actions (forces and torques) can become a very labour-intensive and non-trivial task, especially if the domain includes a large number of bodies or if it requires complicated chains of inter-body collisions to achieve the desired goal state. Furthermore, there are some interactive applications that rely on rigid body models where no control guidance by a human animator can be offered at runtime, such as video games. In this work, we present techniques to automatically generate intelligent control actions for rigid body simulations. We introduce sampling-based motion planning methods that allow us to model goal-driven behaviour through the use of non-deterministic,Tactics,that consist of intelligent, sampling-based control-blocks, called,Skills. We introduce and compare two variations of a Tactics-driven planning algorithm, namely behavioural Kinodynamic Rapidly Exploring Random Trees (BK-RRT) and Behavioural Kinodynamic Balanced Growth Trees (BK-BGT). We show how our planner can be applied to automatically compute the control sequences for challenging physics-based domains and that is scalable to solve control problems involving several hundred interacting bodies, each carrying unique goal constraints. [source] Dynamic COI-tracking concept for the control of generators in multi-machine power systemsEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 1 2008Zhou Lan Abstract In the conventional excitation control concept, the power angle and frequency of a generator are driven to a pre-designed operation point after the fault occurs. It is named as Constant Point Stabilization (CPS) concept in this paper. A novel concept, called dynamic Center of Inertia (COI)-tracking concept is proposed in this paper. In the concept, the power angle and frequency of each generator track the dynamic COI of the power system. Compared to CPS concept, a salient feature the suggested dynamic COI-tracking concept has is that the generators are not restricted to constant angle point or frequency any longer but track the dynamic COI trajectory of the system to keep synchronous in rotor angle and frequency. Wide area measurement system (WAMS) will be used to transform COI signals to each generator. The time delay within a certain limit of WAMS signals is permitted. To make comparison between the two concepts, the control system models based on the two concepts are first established. Then, using the back-stepping method, two robust controllers are designed to achieve the control objectives of the two concepts. At last, dynamic simulations are carried out based on a 2-area-4-machine test power system, and the control effects of the two controllers, together with that of the conventional AVR,+,PSS excitation system, are compared. Copyright © 2007 John Wiley & Sons, Ltd. [source] Integrating modelling and experiments to assess dynamic musculoskeletal function in humansEXPERIMENTAL PHYSIOLOGY, Issue 2 2006J. W. Fernandez Magnetic resonance imaging, bi-plane X-ray fluoroscopy and biomechanical modelling are enabling technologies for the non-invasive evaluation of muscle, ligament and joint function during dynamic activity. This paper reviews these various technologies in the context of their application to the study of human movement. We describe how three-dimensional, subject-specific computer models of the muscles, ligaments, cartilage and bones can be developed from high-resolution magnetic resonance images; how X-ray fluoroscopy can be used to measure the relative movements of the bones at a joint in three dimensions with submillimetre accuracy; how complex 3-D dynamic simulations of movement can be performed using new computational methods based on non-linear control theory; and how musculoskeletal forces derived from such simulations can be used as inputs to elaborate finite-element models of a joint to calculate contact stress distributions on a subject-specific basis. A hierarchical modelling approach is highlighted that links rigid-body models of limb segments with detailed finite-element models of the joints. A framework is proposed that integrates subject-specific musculoskeletal computer models with highly accurate in vivo experimental data. [source] Learning to recognize vulnerable patterns due to undesirable Zone-3 relay operationsIEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 3 2009Koji Yamashita Member Abstract Undesirable zone 3 relay operations caused by unexpected loading conditions can contribute to the cascaded events, leading to catastrophic outages. Identifying the basic patterns of zone 3 relay operations in advance is an effective way to help prevent cascaded events. The postcontingency impedances seen by zone 3 relays can be calculated on line in a steady state security assessment framework. However, their accuracy is inadequate compared with the postcontingency apparent impedance obtained from off-line time domain dynamic simulations. This paper proposes a fuzzy inference system (FIS) to correct discrepancies between the postcontingency apparent impedances obtained from the results of steady state security assessment and the corresponding values obtained by time-domain simulations. The postcontingency apparent impedances obtained from the results of steady state security assessment can be corrected on line using correction terms provided by the FIS. The dynamic model of a 200-bus system is used to validate the performance of the proposed FIS. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source] The evaluation of small cogeneration for residential heatingINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 13 2002Kris R. Voorspools Abstract The decision whether or not to install small cogeneration for residential purposes mainly depends on individual economic considerations, combined with ecological awareness. Since in most cases, the economic balance is still unfavourable, government grants are considered in order to bridge this economic barrier. It is however still unclear how these grants are best spent to obtain an optimal environmental benefit. In the case of cogeneration, mainly static and simplified methods are used, completely neglecting the dynamic interaction between the cogeneration systems and the central power system and the dynamic response of the cogeneration units themselves. In this paper, these issues are discussed in two parts. The first part clarifies how an actual cogeneration unit, if necessary in combination with a back-up boiler and heat storage, will respond to a certain demand. For this purpose, experiments were performed to establish the transient and stationary behaviour of the system. It is shown that the transient heating of the cogeneration engine is rather slow (e.g. half an hour after cold start, the engine only produced 65% of the heat it would have in stationary regime) where the electric transient behaviour is negligible. In the second part of the paper, dynamic simulations are performed to quantify the impact (primary energy saving and reduction in greenhouse-gas emissions) of the massive installation of cogeneration for residential heating. Two important parameters are isolated. First, the interaction with the expansion of the central power system is very important. If the installation of cogeneration prevents the commissioning of new power plants, the potential energy saving and (especially) emission reduction are reduced. The second parameter is the annual use of the cogeneration units. Here, the potential energy saving and emission reduction increase with increasing annual use. Copyright © 2002 John Wiley & Sons, Ltd. [source] Bacillus subtilis Esterase (BS2) and its Double Mutant Have Different Selectivity in the Removal of Carboxyl Protecting GroupsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14-15 2009Efrosini Barbayianni Abstract An esterase from Bacillus subtilis (BS2) and its double mutant E188W/M193C quickly hydrolyze n -butyl, n -propyl, methoxyethyl and allyl esters. The wild-type BS2 preferentially removes such esters from the ,-position of glutamate diesters, while the engineered enzyme has a reversed selectivity removing esters from the ,-position of glutamate diesters. Automated docking and molecular dynamic simulations were performed to understand the molecular reason for the different regioselectivity. [source] Ramachandran-type plots for glycosidic linkages: Examples from molecular dynamic simulations using the Glycam06 force fieldJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 6 2009Amanda M. Salisburg Abstract The goals of this article are to (1) provide further validation of the Glycam06 force field, specifically for its use in implicit solvent molecular dynamic (MD) simulations, and (2) to present the extension of G.N. Ramachandran's idea of plotting amino acid phi and psi angles to the glycosidic phi, psi, and omega angles formed between carbohydrates. As in traditional Ramachandran plots, these carbohydrate Ramachandran-type (carb-Rama) plots reveal the coupling between the glycosidic angles by displaying the allowed and disallowed conformational space. Considering two-bond glycosidic linkages, there are 18 possible conformational regions that can be defined by (,, ,, ,) and (,, ,, ,), whereas for three-bond linkages, there are 54 possible regions that can be defined by (,, ,, ,, ,) and (,, ,, ,, ,). Illustrating these ideas are molecular dynamic simulations on an implicitly hydrated oligosaccharide (700 ns) and its eight constituent disaccharides (50 ns/disaccharide). For each linkage, we compare and contrast the oligosaccharide and respective disaccharide carb-Rama plots, validate the simulations and the Glycam06 force field through comparison to experimental data, and discuss the general trends observed in the plots. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2009 [source] Theoretical study of the interaction between a high-valent manganese porphyrin oxyl-(hydroxo)-Mn(IV)-TMPyP and double-stranded DNAJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 7 2003Philippe Arnaud Abstract Cationic porphyrin derivatives such as meso-tetrakis(4- N -methylpyridinium)porphyrin, TMPyP, have been shown to interact with double-stranded DNA. The manganese derivative, Mn(III)-TMPyP, activated by an oxygen donor like potassium monopersulfate, provides an efficient DNA-cleaving system. Previous experimental work1 has shown that DNA cleavage by the Mn(III)-TMPyP/KHSO5 system was due to an oxidative attack, within the minor groove of B-DNA, at the C5, or C1, carbons of deoxyribose units. The aim of this study was to use molecular modeling to elucidate the specificity of the interactions between the transient active species oxyl-Mn(IV)-TMPyP and the DNA target. Geometric parameters, charges, and force field constants consistent with the AMBER 98 force field were calculated by DFT methods. Molecular modeling (mechanics and dynamic simulations) were performed for oxyl-(hydroxo)-Mn(IV)-TMPyP bound in the minor groove of the dodecamer d(5,-TCGTCAAACCGC)-d(5,-GCGGTTTGACGA). Geometry, interactions, and binding energy of the metalloporphyrin located at the A.T triplet region of the dodecamer were analyzed. These studies show no significant structural change of the DNA structure upon ligand binding. Mobility of the metalloporphyrin in the minor groove was restrained by the formation of a hydrogen bond between the hydroxo ligand trans to the metal-oxyl and a DNA phosphate, restricting the access of the oxyl group to the (pro-S) H atom at C5,. © 2003 Wiley Periodicals, Inc. J Comput Chem 24: 797,805, 2003 [source] Simulation-based actuator selection for redundantly actuated robot mechanismsJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 8 2002Yong-Hoon Lee This article presents a simulation-based strategy for sizing the actuators of a redundantly actuated robotic mechanism. The class of robotic mechanisms we consider may contain one or more closed loops and possess an arbitrary number of active and passive joints, and the number of actuators may exceed the mechanism's kinematic degrees of freedom. Our approach relies on a series of dynamic simulations of the mechanism, by applying Taguchi's method to systematically perform the simulations. To efficiently perform each of the dynamic simulations, we develop, using tools from modern screw theory, new recursive algorithms for the forward and inverse dynamics of the class of redundantly actuated mechanisms described. © 2002 Wiley Periodicals, Inc. [source] | ||||||||||||||||||||||||||||||||||