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Dynamic Systems (dynamic + system)
Kinds of Dynamic Systems Selected AbstractsChemInform Abstract: Molecular Amplification in a Dynamic System by Ammonium Cations.CHEMINFORM, Issue 17 2002Ricardo L. E. Furlan Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] INTEGRATING DYNAMIC SYSTEMS MATERIALS INTO A MECHANICAL ENGINEERING CURRICULUM THROUGH INNOVATIVE USE OF WEB-BASED ACQUISITION AND HANDS-ON APPLICATION AND USE OF VIRTUAL GRAPHICAL USER INTERFACES Part 3: Dynamic Systems,Analytical and Experimental System CharacterizationEXPERIMENTAL TECHNIQUES, Issue 1 2008Pete Avitabile First page of article [source] Computer Algebra Algorithms for Control Related Tests of Implicit Dynamic SystemsPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2003Kurt Schlacher This contribution is focused on control related tests for implicit dynamic systems, like accessibility, observability or input to output, input to state linearizability. Since the performance of these tests needs tedious symbolic calculations, computer algebra systems are the ideal tool to cope with this problem. Accessibility and observability are exemplarily used to present a new approach based on Lie groups. It is shown that non accessible or non observable systems admit Lie-groups acting on their solutions such that distinguished parts remain unchanged. This fact allows us to apply this technique, as well as its realization by computer algebra algorithm, to several fundamental problems in control. [source] Dynamic Systems of Petroleum Accumulation in the Nanpu Depression, Bohai Bay Basin, ChinaACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 5 2010LIU Guangdi Abstract: It is significant to distinguish the dynamic systems of petroleum accumulation (DSPA) for the understanding of petroleum accumulation and distribution. According to the formation pressure framework, genetic types of petroleum and characteristics of conduit systems, three dynamic systems of petroleum accumulation were identified in the vertical profile in the Nanpu depression, Bohai Bay basin. The deeper DSPA (including formations Es3 to Es2) is a sealed system with high-overpressure and high-mature self-sourced oil. Most of the crude oil in the system accumulated in the periods of late Oligocene (23.5 Ma) and late Pliocene (2.4 Ma). The middle DSPA (including formations Es1 to Ed1) is an overpressured half-sealed system with mature or lower-mature self-sourced oil. The accumulation of oil in the system also occurred in the late Oligocene (23.5 Ma) and late Pliocene (2.4 Ma). The shallower DSPA (including formations Ed2 to Q) is a hydrostatic system with lower-mature alien-sourced oil from the middle system. Oil within this system accumulated only in the late Pliocene period. The oil in the shallower system migrated vertically along the faults from the formerly accumulated oil in the middle system by lateral migration along the sandbodies, whereas petroleum accumulation in the deeper system was mainly derived from the system itself by lateral migration along the sandbodies and rarely migrated out of the system. In this case, it seems that the deeper system is a more potential exploration prospect in addition to the other two proved favorable systems. [source] BONDSYM: SIMULINK-based educational software for analysis of dynamic systemCOMPUTER APPLICATIONS IN ENGINEERING EDUCATION, Issue 2 2010J.A. Calvo Abstract This article presents an educational software called BONDSYM developed to allow engineering students to learn easily and quickly about the analysis of dynamic systems through the Bond Graph method. This software uses the SIMULINK library of MATLAB, which has proven to be an excellent choice in order to implement and solve the dynamic equations involved. The application allows for the representation of the behavior of a dynamic system analyzed through the Bond Graph theory in order to understand the dynamic equations and the physical phenomena involved. Based on block diagram of SIMULINK, the different "bonds" of Bond Graph can be integrated as SIMULINK blocks in order to generate the dynamic model. A few simple models are analyzed through this application. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 18: 238,251, 2010; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20246 [source] Physically Guided Animation of TreesCOMPUTER GRAPHICS FORUM, Issue 2 2009Ralf Habel Abstract This paper presents a new method to animate the interaction of a tree with wind both realistically and in real time. The main idea is to combine statistical observations with physical properties in two major parts of tree animation. First, the interaction of a single branch with the forces applied to it is approximated by a novel efficient two step nonlinear deformation method, allowing arbitrary continuous deformations and circumventing the need to segment a branch to model its deformation behavior. Second, the interaction of wind with the dynamic system representing a tree is statistically modeled. By precomputing the response function of branches to turbulent wind in frequency space, the motion of a branch can be synthesized efficiently by sampling a 2D motion texture. Using a hierarchical form of vertex displacement, both methods can be combined in a single vertex shader, fully leveraging the power of modern GPUs to realistically animate thousands of branches and ten thousands of leaves at practically no cost. [source] Soil metaproteomics: a review of an emerging environmental science.EUROPEAN JOURNAL OF SOIL SCIENCE, Issue 6 2009Significance, methodology, perspectives Summary Soil is a dynamic system in which microorganisms perform important tasks in organic matter transformations and nutrient cycles. Recently, some studies have started to focus on soil metaproteomics as a tool for understanding the function and the role of members of the microbial community. The aim of our work was to provide a review of soil proteomics by looking at the methodologies used in order to illustrate the challenges and gaps in this field, and to provide a broad perspective about the use and meaning of soil metaproteomics. The development of soil metaproteomics is influenced strongly by the extraction methods. Several methods are available but only a few provide an identification of soil proteins, while others extract proteins and are able to separate them by electrophoresis but do not provide an identification. The extraction of humic compounds together with proteins interferes with the latter's separation and identification, although some methods can avoid these chemical interferences. Nevertheless, the major problems regarding protein identification reside in the fact that soil is a poor source of proteins and that there is not enough sequence-database information for the identification of proteins by mass spectrometric analysis. Once these pitfalls have been solved, the identification of soil proteins may provide information about the biogeochemical potential of soils and pollutant degradation and act as an indicator of soil quality, identifying which proteins and microorganisms are affected by a degradation process. The development of soil metaproteomics opens the way to proteomic studies in other complex substrates, such as organic wastes. These studies can be a source of knowledge about the possibility of driven soil restoration in polluted and degraded areas with low organic matter content and even for the identification of enzymes and proteins with a potential biotechnological value. [source] The Kalman filter for the pedologist's tool kitEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 6 2006R. Webster Summary The Kalman filter is a tool designed primarily to estimate the values of the ,state' of a dynamic system in time. There are two main equations. These are the state equation, which describes the behaviour of the state over time, and the measurement equation, which describes at what times and in what manner the state is observed. For the discrete Kalman filter, discussed in this paper, the state equation is a stochastic difference equation that incorporates a random component for noise in the system and that may include external forcing. The measurement equation is defined such that it can handle indirect measurements, gaps in the sequence of measurements and measurement errors. The Kalman filter operates recursively to predict forwards one step at a time the state of the system from the previously predicted state and the next measurement. Its predictions are optimal in the sense that they have minimum variance among all unbiased predictors, and in this respect the filter behaves like kriging. The equations can also be applied in reverse order to estimate the state variable at all time points from a complete series of measurements, including past, present and future measurements. This process is known as smoothing. This paper describes the ,predictor,corrector' algorithm for the Kalman filter and smoother with all the equations in full, and it illustrates the method with examples on the dynamics of groundwater level in the soil. The height of the water table at any one time depends partly on the height at previous times and partly on the precipitation excess. Measurements of the height of water table and their errors are incorporated into the measurement equation to improve prediction. Results show how diminishing the measurement error increases the accuracy of the predictions, and estimates achieved with the Kalman smoother are even more accurate. Le filtre de Kalman comme outil pour le pédologue Résumé Le filtre de Kalman est un outil conçu essentiellement pour estimer les valeurs de l'état d'un système dynamique dans le temps. Il comprend deux équations principales. Celles-ci sont l'équation d'état, qui décrit l'évolution de l'état pendant le temps, et l'équation de mesure qui decrit à quel instants et de quelle façon on observe l'état. Pour le filtre discret de Kalman, décrit dans cet article, l'équation d'état est une équation stochastique différentielle qui comprend une composante aléatoire pour le bruit dans le système et qui peut inclure une force extérieure. On définit l'équation de mesure de façon à ce qu'elle puisse traiter des mesures indirectes, des vides dans des séquences de mesures et des erreurs de mesure. Le filtre de Kalman fonctionne récursivement pour prédire en avance une démarche à temps l'état du système de la démarche prédite antérieure plus l'observation prochaine. Ses prédictions sont optimales dans le sens qu'elles minimisent la variance parmi toutes les prédictions non-biasées, et à cet égard le filtre se comporte comme le krigeage. On peut appliquer, aussi, les équations dans l'ordre inverse pour estimer la variable d'état à toutes pointes à toutes les instants d'une série complète d'observations, y compris les observations du passé, du présent et du futur. Ce processus est connu comme ,smoothing'. Cet article décrit l'algorithme ,predictor,corrector' du filtre de Kalman et le ,smoother' avec toutes les équations entières. Il illustre cette méthode avec des exemples de la dynamique du niveau de la nappe phréatique dans le sol. Le niveau de la nappe à un instant particulier dépend en partie du niveau aux instants précédents et en partie de l'excès de la précipitation. L'équation d'état fournit la relation générale entre les deux variables et les prédictions. On incorpore les mesures du niveau de la nappe et leurs erreurs pour améliorer les prédictions. Les résultats mettent en évidence que lorsqu'on diminue l'erreur de mesure la précision des prédictions augmente, et aussi que les estimations avec le ,smoother' de Kalman sont encore plus précises. [source] Automatic tuning of L2 -SVM parameters employing the extended Kalman filterEXPERT SYSTEMS, Issue 2 2009Tingting Mu Abstract: We show that tuning of multiple parameters for a 2-norm support vector machine (L2 -SVM) could be viewed as an identification problem of a nonlinear dynamic system. Benefiting from the reachable smooth nonlinearity of an L2 -SVM, we propose to employ the extended Kalman filter to tune the kernel and regularization parameters automatically for the L2 -SVM. The proposed method is validated using three public benchmark data sets and compared with the gradient descent approach as well as the genetic algorithm in measures of classification accuracy and computing time. Experimental results demonstrate the effectiveness of the proposed method in higher classification accuracies, faster training speed and less sensitivity to the initial settings. [source] Dynamical similarity of explosions at Stromboli volcanoGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 3 2004S. De Martino SUMMARY We analyse Strombolian explosions recorded with broadband seismometers to quantify the degree of similarity among explosions. First, we construct the trajectory space. This reconstruction is analogous to that of phase space but, unlike the phase space which relies on the analysis of a single trajectory of a dynamic system, the trajectory space takes into account many trajectories of the dynamic process to study the overlapping properties. Based on the scaling of distances between each pair of histories, it is possible to evaluate the dimension of the trajectory space. We consider the different explosions as different trajectories and, after normalizing all the records, we find that the scaling region is spread over less than one order of magnitude. This absence of scaling implies that all the trajectories cover the same attractor in the trajectory space, and that the trajectories are generated by the same dynamic system. Accordingly, we conclude that all the events are very similar to each other. This result is confirmed by the energy distribution of these events. Standard techniques of energy estimation are inadequate in this case, and we propose an evaluation method based on a quantity that is proportional to energy. The distribution function of this quantity, calculated on 580 events, displays a log-normal behaviour with very low variability (less than two orders of magnitude in energy). These results provide quantitative support for the observation that there is a great degree of similarity among Strombolian explosions and support the idea that a dynamic model underlying these events can be elaborated through the study of just one event. [source] Additivity properties of graphs with Form II symmetryINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 3 2006A. Kaveh Abstract In this paper, the properties of previously developed Form II symmetry (Commun. Numer. Meth. Engng 2003; 19:125,136; 2004; 20:133,146) is further investigated. Additivity properties of graphs with this form are formulated, and the effect of adding or deleting members on the eigenvalues of the Laplacian matrices of the corresponding graphs, is studied. Depending on the category of the added or deleted members, the condensed submatrices on which changes occur are identified, and the necessary modifications are suggested. A mass-spring dynamic system is presented to illustrate a typical application of the latter approach. Copyright © 2005 John Wiley & Sons, Ltd. [source] Vertical dynamic responses of a simply supported bridge subjected to a moving train with two-wheelset vehicles using modal analysis methodINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 9 2005Ping Lou Abstract The vertical dynamic responses of a simply supported bridge subjected to a moving train are investigated by means of the modal analysis method. Each vehicle of train is modelled as a four-degree-of-freedom mass,spring,damper multi-rigid body system with a car body and two wheelsets. The bridge, together with track, is modelled as a simply supported Bernoulli,Euler beam. The deflection of the beam is described by superimposing modes. The train and the beam are regarded as an entire dynamic system, in which the contact forces between wheelset and beam are considered as internal forces. The equations of vertical motion in matrix form with time-dependent coefficients for this system are directly derived from the Hamilton's principle. The equations of motion are solved by Wilson-, method to obtain the dynamic responses for both the support beam and the moving train. Compared with the results previous reported, good agreement between the proposed method and the finite element method is obtained. Finally, the effects of beam mode number, vehicle number, beam top surface, and train velocity on the dynamic responses of the entire train and bridge coupling system are studied, and the dynamic responses of beam are given under the train moving with resonant velocity. Copyright © 2005 John Wiley & Sons, Ltd. [source] Stability of linear time-periodic delay-differential equations via Chebyshev polynomialsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 7 2004Eric A. Butcher Abstract This paper presents a new technique for studying the stability properties of dynamic systems modeled by delay-differential equations (DDEs) with time-periodic parameters. By employing a shifted Chebyshev polynomial approximation in each time interval with length equal to the delay and parametric excitation period, the dynamic system can be reduced to a set of linear difference equations for the Chebyshev expansion coefficients of the state vector in the previous and current intervals. This defines a linear map which is the ,infinite-dimensional Floquet transition matrix U'. Two different formulas for the computation of the approximate U, whose size is determined by the number of polynomials employed, are given. The first one uses the direct integral form of the original system in state space form while the second uses a convolution integral (variation of parameters) formulation. Additionally, a variation on the former method for direct application to second-order systems is also shown. An error analysis is presented which allows the number of polynomials employed in the approximation to be selected in advance for a desired tolerance. An extension of the method to the case where the delay and parametric periods are commensurate is also shown. Stability charts are produced for several examples of time-periodic DDEs, including the delayed Mathieu equation and a model for regenerative chatter in impedance-modulated turning. The results indicate that this method is an effective way to study the stability of time-periodic DDEs. Copyright © 2004 John Wiley & Sons, Ltd. [source] A fractional adaptation law for sliding mode controlINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 10 2008Mehmet Önder Efe Abstract This paper presents a novel parameter tuning law that forces the emergence of a sliding motion in the behavior of a multi-input multi-output nonlinear dynamic system. Adaptive linear elements are used as controllers. Standard approach to parameter adjustment employs integer order derivative or integration operators. In this paper, the use of fractional differentiation or integration operators for the performance improvement of adaptive sliding mode control systems is presented. Hitting in finite time is proved and the associated conditions with numerical justifications are given. The proposed technique has been assessed through a set of simulations considering the dynamic model of a two degrees of freedom direct drive robot. It is seen that the control system with the proposed adaptation scheme provides (i) better tracking performance, (ii) suppression of undesired drifts in parameter evolution, (iii) a very high degree of robustness and improved insensitivity to disturbances and (iv) removal of the controller initialization problem. Copyright © 2008 John Wiley & Sons, Ltd. [source] Nonlinear Laguerre,Volterra observer-controller and its application to process controlINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 4 2010Hai-Tao Zhang Abstract By expanding each kernel using the orthonormal Laguerre series, a Volterra functional series is used to represent the input/output relation of a nonlinear dynamic system. With the feedback of the modeling error, we design a novel nonlinear state observer, based on which an output feedback controller is derived for both the stabilization and tracking problems. The stability of the closed-loop system is analyzed theoretically. The algorithm is effectively applied on the continuous stirring tank reactor and chemical reactor temperature control system. Copyright © 2009 John Wiley & Sons, Ltd. [source] Real-time optimization of dynamic systems using multiple unitsINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 13 2007B. Srinivasan Abstract Model-free, unconstrained, real-time optimization of the operating point of a dynamic system involves forcing the gradient of the cost function to zero. In these methods, gradient estimation is a key issue, for which methods that perturb the input over time are used. The main limitation of these methods is that they require the dynamics of the adaptation to be two orders of magnitude slower than the system dynamics. To circumvent this limitation, a novel, simple, yet effective way of estimating the gradient is presented in this paper. Multiple identical units with non-identical inputs are used and the gradient is computed via finite difference. Thus, the perturbation is along the ,unit dimension', thereby allowing a faster adaptation. The convergence of the scheme is rigorously established via Lyapunov analysis. An illustrative example is provided where the proposed scheme resulted in an 100-fold improvement in the time needed for convergence. Copyright © 2007 John Wiley & Sons, Ltd. [source] Robust output regulation for discrete-time nonlinear systemsINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 2 2005Weiyao Lan Abstract In this paper, we will establish a framework that can convert the robust output regulation problem for discrete-time nonlinear systems into a robust stabilization problem for an appropriately augmented system consisting of the given plant and a specific dynamic system called internal model. We then apply this framework to solve the local robust output regulation problem for a general class of discrete-time nonlinear systems. The results of this paper gives a discrete-time counterpart of the recent results on the continuous-time robust output regulation problem. Copyright © 2005 John Wiley & Sons, Ltd. [source] Modelling the distribution of a threatened habitat: the California sage scrubJOURNAL OF BIOGEOGRAPHY, Issue 11 2009Erin C. Riordan Abstract Aim, Using predictive species distribution and ecological niche modelling our objectives are: (1) to identify important climatic drivers of distribution at regional scales of a locally complex and dynamic system , California sage scrub; (2) to map suitable sage scrub habitat in California; and (3) to distinguish between bioclimatic niches of floristic groups within sage scrub to assess the conservation significance of analysing such species groups. Location, Coastal mediterranean-type shrublands of southern and central California. Methods, Using point localities from georeferenced herbarium records, we modelled the potential distribution and bioclimatic envelopes of 14 characteristic sage scrub species and three floristic groups (south-coastal, coastal,interior disjunct and broadly distributed species) based upon current climate conditions. Maxent was used to map climatically suitable habitat, while principal components analysis followed by canonical discriminant analysis were used to distinguish between floristic groups and visualize species and group distributions in multivariate ecological space. Results, Geographical distribution patterns of individual species were mirrored in the habitat suitability maps of floristic groups, notably the disjunct distribution of the coastal,interior species. Overlap in the distributions of floristic groups was evident in both geographical and multivariate niche space; however, discriminant analysis confirmed the separability of floristic groups based on bioclimatic variables. Higher performance of floristic group models compared with sage scrub as a whole suggests that groups have differing climate requirements for habitat suitability at regional scales and that breaking sage scrub into floristic groups improves the discrimination between climatically suitable and unsuitable habitat. Main conclusions, The finding that presence-only data and climatic variables can produce useful information on habitat suitability of California sage scrub species and floristic groups at a regional scale has important implications for ongoing efforts of habitat restoration for sage scrub. In addition, modelling at a group level provides important information about the differences in climatic niches within California sage scrub. Finally, the high performance of our floristic group models highlights the potential a community-level modelling approach holds for investigating plant distribution patterns. [source] Developing a model for quality evaluation in residential care for people with intellectual disabilityJOURNAL OF INTELLECTUAL DISABILITY RESEARCH, Issue 5 2000B. Maes Abstract The present article describes the development of a general model for the evaluation, enhancement and assurance of quality of care processes in residential facilities for children and adults with intellectual disability. The framework is based on current theories regarding quality of life and quality evaluation, on a consensus between several participants in Delphi discussion-rounds, and on a questionnaire for care providers and clients in all Flemish residential facilities. The model describes 13 quality standards and a list of indicators concerning organization and support interventions. Facilities may use this set of criteria and indicators in several ways within a continuous and dynamic system of internal quality assurance. Finally, the prospects of and conditions for the implementation of this model are discussed. [source] A simulation-optimization framework for research and development pipeline managementAICHE JOURNAL, Issue 10 2001Dharmashankar Subramanian The Research and Development Pipeline management problem has far-reaching economic implications for new-product-development-driven industries, such as pharmaceutical, biotechnology and agrochemical industries. Effective decision-making is required with respect to portfolio selection and project task scheduling in the face of significant uncertainty and an ever-constrained resource pool. The here-and-now stochastic optimization problem inherent to the management of an R&D Pipeline is described in its most general form, as well as a computing architecture, Sim-Opt, that combines mathematical programming and discrete event system simulation to assess the uncertainty and control the risk present in the pipeline. The R&D Pipeline management problem is viewed in Sim-Opt as the control problem of a performance-oriented, resource-constrained, stochastic, discrete-event, dynamic system. The concept of time lines is used to study multiple unique realizations of the controlled evolution of the discrete-event pipeline system. Four approaches using various degrees of rigor were investigated for the optimization module in Sim-Opt, and their relative performance is explored through an industrially motivated case study. Methods are presented to efficiently integrate information across the time lines from this framework. This integration of information demonstrated in a case study was used to infer a creative operational policy for the corresponding here-and-now stochastic optimization problem. [source] Systematic estimation of state noise statistics for extended Kalman filtersAICHE JOURNAL, Issue 2 2000Jaleel Valappil The successful application of model-based control depends on the information about the states of the dynamic system. State-estimation methods, like extended Kalman filters (EKF), are useful for obtaining reliable estimates of the states from a limited number of measurements. They also can handle the model uncertainties and the effect of unmeasured disturbances. The main issue in applying EKF remains that one needs to specify the confidence in the model in terms of process noise covariance matrix. The information about the model uncertainties can effectively and systematically calculate the process noise covariance matrix for an EKF. Two systematic approaches are used for this calculation. The first is based on a Taylor series expansion of the nonlinear equations around the nominal parameter values, while the second accounts for the nonlinear dependence of the system on the fitted parameters by Monte Carlo simulations that can easily be performed on-line. The value of the process noise covariance matrix obtained is not limited to a diagonal form and depends on the current state of the dynamic system. Thus the a-priori information regarding the uncertainty in the model is utilized and the need for extensive tuning of the EKF is eliminated. The application of these techniques to example processes is also discussed. The accuracy of this methodology is compared very favorably with the traditional methods of trial-and-error tuning of EKF. [source] The effects of water retention time and watershed features on the limnology of two tropical reservoirs in BrazilLAKES & RESERVOIRS: RESEARCH AND MANAGEMENT, Issue 4 2008Maria Carolina S. Soares Abstract Although reservoirs are similar to natural lakes in many respects, such driving forces as water retention time and watershed features can play important roles in the limnology of manmade lakes. With the goal of investigating how these factors influence the limnology of tropical reservoirs, physical and chemical variables were measured at four sampling sites in two reservoirs in southern Brazil, from June 2002 to June 2003. Funil Reservoir is located in one of the most-populated areas in the country, in the Paraíba do Sul river basin, which drains and drastically influences the water quality of the reservoir. In contrast, Lajes Reservoir is located in a well-preserved area, with its water retention time varying from six to 30 times longer than for Funil Reservoir. Funil Reservoir is a turbid (median euphotic zone = 4.3 m), eutrophic reservoir (median total phosphorus (TP) = 3.1 µm), with a high phytoplankton biomass (median chlorophyll- a concentration = 10.0 µg L,1). In contrast, Lajes Reservoir is a transparent (median euphotic zone = 9.2 m), mesotrophic water system (median TP = 1.0 µm), with a low phytoplankton biomass (median chlorophyll- a = 1.9 µg L,1). Both reservoirs were stratified during the summer months, but isothermy was only observed in Funil Reservoir. Because of its short water retention time, Funil Reservoir is a much more dynamic system than Lajes Reservoir, with a pronounced temporal pattern related to changes in its water column and its phytoplankton biomass. Spatial heterogeneity is more evident in Lajes Reservoir, mainly as a consequence of its location in a preserved area, long water retention time and the presence of net cages for fish culture in the waterbody. The typical spatial zonation found in reservoirs, related to nutrient sedimentation and light availability, however, is more evident in Funil Reservoir than in Lajes Reservoir. Despite the similarities between these two water systems, which are in the same geographical region with similar climate, and are comparable in size, the distinct watershed features and water retention time are responsible for marked differences between these reservoirs. [source] Chemiluminescent picture of diphenyleneiodonium-inhibited NADPH oxidase: a bimodal process and its logistic,exponential model-based descriptionLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 4 2007Bonawentura Kochel Abstract A chemiluminescence (CL) study of diphenyleneiodonium-inhibited NADPH oxidase was performed on a cellular system containing neutrophils stimulated by phorbol myristate acetate, indicating a complex bimodal structure of CL processes corresponding to different stages of the inhibition. The complex structure of these processes was described by a superposition of two logistic,exponential (LE) models, characterizing these processes as bimodal ones. To determine the mechanistic foundation of the LE model-described processes, a generalized form of the second-order dynamic system of CL reactions, the solution to which corresponds to the LE model, was constructed. The diphenyleneiodonium effects on neutrophil NADPH oxidase were separated from the total bimodal CL of the whole measurement system by the use of difference CL processes. These difference processes were also found to be bimodal; thus, inhibitor-induced reduction of CL could be described by a second-order dynamic system. The rate constants and initial concentrations in this dynamic system were determined by the least squares method applied to numerical solutions approximating the difference processes. Using interrelations between the parameters of the dynamic system, cooperative effects in the inhibitor reactions with NADPH oxidase were found and described quantitatively. Other evidences of cooperativity were obtained from integral characteristics of the CL reduction process, i.e. dose,response and progress curves, determined by numerical integration of the LE models constituting the superposition. On this basis, it was also possible to detect a specific binding of the inhibitor to the enzyme. Finally, putative reaction mechanisms suggested by the model obtained were considered and compared with those known at present. Copyright © 2007 John Wiley & Sons, Ltd. [source] The Morphology and Dynamics of Substrate Effects on Spinodal Decomposition in Binary Mixtures with Short-Range PotentialMACROMOLECULAR THEORY AND SIMULATIONS, Issue 3 2006Li-Tang Yan Abstract Summary: The SDSD of binary mixture with short-range potential is numerically simulated in 3D by cell dynamic system (CDSs), focusing on the phase morphology and dynamics in the parallel cross-sections. The formation mechanism and growth law of the wetting layer are analyzed taking thermal noise effects into account. The simulated results show that the phase inversion in the parallel cross-sections can be observed near the substrate interface. Without thermal noise, the growth law of the wetting layer is simply logarithmic. However, when the strength of thermal noise is large enough, the LS growth law can be found for a short-range surface field. The results demonstrate that thermal noise can increase the extent of phase separation and lead to a transformation between partial and complete wetting for the substrate interface. The evolution of the phase in the parallel cross-sections obeys the LS growth law and is self-similar regardless of the effects of thermal noise. Simulated pattern evolution at different values of z at ,,=,1,000 with G,=,0. [source] Introduction: Second Language Development as a Dynamic ProcessMODERN LANGUAGE JOURNAL, Issue 2 2008KEES DE BOT In this contribution, some of the basic characteristics of complex adaptive systems, collectively labeled Dynamic Systems Theory (DST), are discussed. Such systems are self-organizing, dependent on initial conditions, sometimes chaotic, and they show emergent properties. The focus in DST is on development over time. Language is seen as a dynamic system, and language development, both acquisition and attrition, as a dynamic process. A number of examples of possible applications of DST in the field of applied linguistics are mentioned. After a short presentation of each of the individual articles, some possible lines of research are discussed. [source] ENTRY AND EXIT OF LABOR AND CAPITAL IN A FISHERYNATURAL RESOURCE MODELING, Issue 2 2005ASGEIR DANIELSSON ABSTRACT. Exit and entry of fishermen, as well as vessels, is modeled explicitly. If the speed of exit and entry of fishermen is less than instantaneous the wage rate varies with the fortunes of the fishing firms and affects the endogenous labor supply creating a second transmission mechanism from profits to effort. There are realistic cases where this mechanism has important effects on the stability of the dynamic system and on the effects of taxes (subsisdies) on the size of the fish stock. If labor supply depends negatively on the wage rate, the immediate effect of an increase in the tax rate is to increase effort and harvest. This condition makes it also more probable that the dynamic system is unstable. In those cases where the dynamic system is unstable the increase in the tax rate increases overexploitation not only in the short-term but also in the long-term. [source] Optimal control of innate immune responseOPTIMAL CONTROL APPLICATIONS AND METHODS, Issue 2 2002Robert F. Stengel Abstract Treatment of a pathogenic disease process is interpreted as the optimal control of a dynamic system. Evolution of the disease is characterized by a non-linear, fourth-order ordinary differential equation that describes concentrations of pathogens, plasma cells, and antibodies, as well as a numerical indication of patient health. Without control, the dynamic model evidences sub-clinical or clinical decay, chronic stabilization, or unrestrained lethal growth of the pathogen, depending on the initial conditions for the infection. The dynamic equations are controlled by therapeutic agents that affect the rate of change of system variables. Control histories that minimize a quadratic cost function are generated by numerical optimization over a fixed time interval, given otherwise lethal initial conditions. Tradeoffs between cost function weighting of pathogens, organ health, and use of therapeutics are evaluated. Optimal control solutions that defeat the pathogen and preserve organ health are demonstrated for four different approaches to therapy. It is shown that control theory can point the way toward new protocols for treatment and remediation of human diseases. Copyright © 2002 John Wiley & Sons, Ltd. [source] Torsional Vibration Damping Through Frictional Torsion Damper with Structural Friction and Slide Taken into ConsiderationPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2005Zbigniew Skup Ph. DSC The paper is concerned with a non-linear discrete stationary mechanical system containing a frictional torsion damper. Proper effect of vibration damping in a two-degree-of freedom system can be reached by the right selection of geometrical parameters for given loads, as pre-determined by a mathematical model. Structural friction was considered, as well as small relative sliding of damper's discs cooperating with a plunger. The system vibrates under harmonic excitation. The problem was considered on the assumption of uniform unit pressure distribution between the contacting surfaces of friction discs and the plunger. When the discs are sliding, the friction coefficient varies, depending on relative angular velocity. Friction characteristics were assumed on the basis of the author's own research and experimental testing by other authors. Properties of the material were assumed to be in accordance with classical theory of elasticity. The author analysed the influence of parameters of the dynamic system upon amplitude and frequency characteristics as well as on phase and frequency characteristics. The equation of motion was solved by means of the slowly-varying-parameters method and, in order to compare the results, by means of numerical simulation. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Using behavior to determine immature life-stages in captive western gorillasAMERICAN JOURNAL OF PRIMATOLOGY, Issue 6 2010J.E. Hutchinson Abstract Ontogenic development is divided into infant, juvenile, adolescent and adult life-stages. Although the developmental trajectory of an individual is a flexible entity, which differs within species, environment and sex, life-stage classifications are generally structured, age-based systems. This invariably leads to rigidity within a dynamic system and consequently hampers our understanding of primate life history strategies. We propose that life-stage classifications should be quantitative, flexible entities, which use a reliable measurement of development. Here, we provide a methodological example where placement into a life-stage is based upon behavioral variance between other similar-aged individuals. Behavioral data were collected from 12 male (3,11 years old) and 9 female (3,8 years old) captive immature western gorillas (Gorilla gorilla gorilla) housed in five family groups, using continuous focal sampling; 900,hr of data were collected over 131 days. Data were applied to four published life-stage classifications for mountain gorillas (Gorilla beringei beringei), which showed variable ability to determine life-stage in western gorillas. A new life-stage classification (Hutchinson & Fletcher) was proposed specifically for western gorillas, whereby multiple co-varying behavior provided a robust measure of linear development across immaturity. Each life-stage was found to be a distinct ontogenic phase and the classification discriminated life-stage with a high level of accuracy. Using the Hutchinson & Fletcher classification we provide evidence for disparity in developmental trajectories between the sexes from the juvenile period onwards. To expand the understanding of primate life histories, we propose that flexible classifications should be used to enable comparison of allometric life history traits within and between species, from birth onwards. Am. J. Primatol. 72:492,501, 2010. © 2010 Wiley-Liss, Inc. [source] Principle of organization: a dynamic-systems view of the archetype-as-suchTHE JOURNAL OF ANALYTICAL PSYCHOLOGY, Issue 4 2001Maxson J. McDowell The personality is a dynamic system. Like all other dynamic systems, it must be self-organized. In this paper I focus upon the archetype-as-such, that is, upon the essential core around which both an archetypal image and a complex are organized. I argue that an archetype-as-such is a pre-existing principle of organization. Within the personality that principle manifests itself as a psychological vortex (a complex) into which we are drawn. The vortex is impersonal. We mediate it through myths and rituals or through consciousness. In this paper I show that Jung's intuition about the archetype-as-such is supported by recent science. I evaluate other concepts of the archetype. My concept is different from that proposed recently by Saunders and Skar. My concept allows each archetype-as-such to be defined precisely in mathematical terms. It suggests a new interpretation of mythology. It also addresses our spiritual experience of an archetype. Because the archetypes-as-such are fundamental to the personality, the better we understand them the better we understand our patients. The paper is grounded with clinical examples. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||