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Dynamic Performance (dynamic + performance)
Selected AbstractsDynamic performance of twin curved cable-stayed bridgesEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 1 2004C. Gentile Abstract The dynamic behaviour of two curved cable-stayed bridges, recently constructed in northern Italy, has been investigated by full-scale testing and theoretical models. Two different excitation techniques were employed in the dynamic tests: traffic-induced ambient vibrations and free vibrations. Since the modal behaviour identified from the two types of test are very well correlated and a greater number of normal modes was detected during ambient vibration tests, the validity of the ambient vibration survey is assessed in view of future monitoring. For both bridges, 11 vibration modes were identified in the frequency range of 0ndash;10Hz, being a one-to-one correspondence between the observed modes of the two bridges. Successively, the information obtained from the field tests was used to validate and improve 3D finite elements so that the dynamic performance of the two systems were assessed and compared based on both the experimental results and the updated theoretical models. Copyright © 2003 John Wiley & Sons, Ltd. [source] Dynamic performance of the beam position monitor support at the SSRFJOURNAL OF SYNCHROTRON RADIATION, Issue 1 2009Xiao Wang Electron beam stability is very important for third-generation light sources, especially for the Shanghai Synchrotron Radiation Facility whose ground vibrations are much larger than those for other light sources. Beam position monitors (BPMs), used to monitor the position of the electron beam, require a greater stability than other mechanical structures. This paper concentrates on an investigation of the dynamic performance of the BPM support prototype. Modal and response analyses have been carried out by finite-element (FE) calculations and vibration measurements. Inconsistent results between calculation and measurement have motivated a change in the soft connections between the support and the ground from a ground bolt in the initial design to full grout. As a result the mechanical stability of the BPM support is greatly improved, showing an increase in the first eigenfrequency from 20.2,Hz to 50.2,Hz and a decrease in the ratio of the root-mean-square displacement (4,50,Hz) between the ground and the top of the support from 4.36 to 1.23 in the lateral direction. An example is given to show how FE analysis can guide the mechanical design and dynamic measurements (i.e. it is not just used as a verification method). Similar ideas can be applied to improve the stability of other mechanical structures. [source] Dynamic performance of twin curved cable-stayed bridgesEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 1 2004C. Gentile Abstract The dynamic behaviour of two curved cable-stayed bridges, recently constructed in northern Italy, has been investigated by full-scale testing and theoretical models. Two different excitation techniques were employed in the dynamic tests: traffic-induced ambient vibrations and free vibrations. Since the modal behaviour identified from the two types of test are very well correlated and a greater number of normal modes was detected during ambient vibration tests, the validity of the ambient vibration survey is assessed in view of future monitoring. For both bridges, 11 vibration modes were identified in the frequency range of 0ndash;10Hz, being a one-to-one correspondence between the observed modes of the two bridges. Successively, the information obtained from the field tests was used to validate and improve 3D finite elements so that the dynamic performance of the two systems were assessed and compared based on both the experimental results and the updated theoretical models. Copyright © 2003 John Wiley & Sons, Ltd. [source] Analyzing dynamic performance of stressed power systems in vicinity of instability by modal series methodEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 8 2009Ali H. Naghshbandy Abstract Highly stressed power systems exhibit complex dynamic behaviors such as inter-area oscillations when subjected to large disturbances. In such conditions, nonlinear effects have dominant role in determining dynamic response of the systems. In this paper by using modal series method, dynamic behaviors of the stressed power systems in severe conditions and near instability have been studied. Also two measures, mode dominance measure (MDM) and most perturbed machine factor (MPF) have been introduced. They determine the most dominant modes and identify the most perturbed generators when the system is subjected to a given fault. Contribution factors have been used to show the links between identified modes and machines from the analysis. Time domain simulation has been helped for validation of the results. By using similarity transformation, state variables have been represented in modal space and utilized to check the results. The studies are carried out on the IEEE 50-generator test system which demonstrates a wide range of dynamic characteristics at different loading levels and fault scenarios. Copyright © 2008 John Wiley & Sons, Ltd. [source] New converter-fed power source to increase the dynamic performance of the three-phase electric arc furnaceEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 6 2000A. Wolf The conventional three-phase electric arc furnaces frequently cause undesired distortions in the power system, which has a low short-circuit capacity in the form of voltage fluctuations (flicker) at the point of common coupling. This is due to the fluctuating reactive power consumption of the furnace. This paper describes a electronic-controlled furnace transformer which enables the reactive power consumed by the furnace to be kept constant. This is made possible if the conventional power system of the three-phase electric arc furnace is supplemented with three-phase power controllers and a booster transformer. By regulating the (reactive) power input, these disturbances can be reduced to a minimum. This new power source was experimentally tested on a single-phase model and the results, which are presented, are very satisfactory. [source] Modelling micro-turbines using Hammerstein modelsINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 9 2005Francisco Jurado Abstract The Hammerstein model configuration, which includes a nonlinear static block followed by a linear dynamic block, is applied to model the static and dynamic characteristics of a micro-turbine. The parameters in the model can be extracted from the measurements of physical engines or from the simulations of physics-based models. In this paper, a nonlinear model is used to assist in the dynamic performance of the micro-turbine when connected to the grid as a distributed generator. Copyright © 2005 John Wiley & Sons, Ltd. [source] Extension of efficient predictive control to the nonlinear caseINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 5 2005M. Bacic Abstract The combined use of the closed-loop paradigm, an augmented autonomous state space formulation, partial invariance, local affine difference inclusion, and polytopic invariance are deployed in this paper to propose an NMPC algorithm which, unlike earlier algorithms that have to tackle online a nonlinear non-convex optimization problem, requires the solution of a simple QP. The proposed algorithm is shown to outperform earlier algorithms in respect of size of region of attraction and online computational load. Conversely, for comparable computational loads, the proposed algorithm outperforms earlier algorithms in terms of optimality of dynamic performance. Copyright © 2005 John Wiley & Sons, Ltd. [source] Gain Scheduled LPV H, Control Based on LMI Approach for a Robotic ManipulatorJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 12 2002Zhongwei Yu A new approach to the design of a gain scheduled linear parameter-varying (LPV) H, controller, which places the closed-loop poles in the region that satisfies the specified dynamic response, for an n -joint rigid robotic manipulator, is presented. The nonlinear time-varying robotic manipulator is modeled to be a LPV system with a convex polytopic structure with the use of the LPV convex decomposition technique in a filter introduced. State feedback controllers, which satisfy the H, performance and the closed-loop pole-placement requirements, for each vertex of the convex polyhedron parameter space, are designed with the use of the linear matrix inequality (LMI) approach. Based on these designed feedback controllers for each vertex, a LPV controller with a smaller on-line computation load and a convex polytopic structure is synthesized. Simulation and experiment results verify that the robotic manipulator with the LPV controller always has a good dynamic performance along with the variations of the joint positions. © 2002 Wiley Periodicals, Inc. [source] Physical characterization of component particles included in dry powder inhalers.JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 5 2007Abstract Characteristics of particles included in dry powder inhalers is extended from our previous report (in this journal) to include properties related to their dynamic performance. The performance of dry powder aerosols for pulmonary delivery is known to depend on fluidization and dispersion which reflects particle interactions in static powder beds. Since the solid state, surface/interfacial chemistry and static bulk properties were assessed previously, it remains to describe dynamic performance with a view to interpreting the integrated database. These studies result in complex data matrices from which correlations between specific properties and performance may be deduced. Lactose particles were characterized in terms of their dynamic flow, powder and aerosol electrostatics, and aerodynamic performance with respect to albuterol aerosol dispersion. There were clear correlations between flow properties and aerosol dispersion that would allow selection of lactose particles for formulation. Moreover, these properties can be related to data reported earlier on the morphological and surface properties of the carrier lactose particles. The proposed series of analytical approaches to the evaluation of powders for inclusion in aerosol products has merit and may be the basis for screening and ultimately predicting particle performance with a view to formulation optimization. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 96: 1302,1319, 2007 [source] Dynamic performance of the beam position monitor support at the SSRFJOURNAL OF SYNCHROTRON RADIATION, Issue 1 2009Xiao Wang Electron beam stability is very important for third-generation light sources, especially for the Shanghai Synchrotron Radiation Facility whose ground vibrations are much larger than those for other light sources. Beam position monitors (BPMs), used to monitor the position of the electron beam, require a greater stability than other mechanical structures. This paper concentrates on an investigation of the dynamic performance of the BPM support prototype. Modal and response analyses have been carried out by finite-element (FE) calculations and vibration measurements. Inconsistent results between calculation and measurement have motivated a change in the soft connections between the support and the ground from a ground bolt in the initial design to full grout. As a result the mechanical stability of the BPM support is greatly improved, showing an increase in the first eigenfrequency from 20.2,Hz to 50.2,Hz and a decrease in the ratio of the root-mean-square displacement (4,50,Hz) between the ground and the top of the support from 4.36 to 1.23 in the lateral direction. An example is given to show how FE analysis can guide the mechanical design and dynamic measurements (i.e. it is not just used as a verification method). Similar ideas can be applied to improve the stability of other mechanical structures. [source] A Short Note About Energy-Efficiency Performance of Thermally Coupled Distillation SequencesTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2006Juan Gabriel Segovia-Hernández Abstract In this work, we present a comparative study of the energy-efficiency performance between conventional distillation sequences and thermally coupled distillation arrangements (TCDS) for the separation of ternary mixtures of hydrocarbons under the action of feedback control loops. The influence of the relative ease of separation of the feed mixture and its composition was analyzed. The feedback analysis was conducted through servo tests with individual changes in the set points for each of the three product streams. Standard PI controllers were used for each loop. The results show an apparent trend regarding the sequence with a better dynamic performance. Generally, TCDS options performed better for the control of the extreme components of the ternary mixture (A and C), while the conventional sequences offered a better dynamic behaviour for the control of the intermediate component (B). The only case in which there was a dominant structure for all control loops was when the feed contained low amounts of the intermediate component and the mixture had similar relative volatilities. The Petlyuk column provided the optimal choice in such case, which contradicts the general expectations regarding its control behaviour. In addition, the energy demands during the dynamic responses were significantly lower than those observed for the other distillation sequences. TCDS options, therefore, are not only more energy efficient than the conventional sequences, but there are cases in which they also offer better feedback control properties. On présente dans ce travail une étude comparative de la performance d'efficacité d'énergétique entre les séquences de distillation conventionnelles et les configurations de distillation couplées thermiquement (TCDS) pour la séparation de mélanges ternaires d'hydrocarbures sous l'action de boucles de contrôle d'asservissement. L'influence de la facilité relative de séparation du mélange d'alimentation et de sa composition est analysée. L'analyse de rétroalimentation est réalisée grâce à des tests d'asservissement avec des changements individuels dans les points de consigne pour chacun des trois courants de produits. Des contrôleurs PI standards ont été utilisés pour chaque boucle. Les résultats montrent une tendance apparente pour la séquence ayant une meilleure performance dynamique. Généralement, les options TCDS sont meilleures pour le contrôle des composantes extrêmes du mélange ternaire (A et C), tandis que les séquences conventionnelles offrent un meilleur contrôle dynamique pour le contrôle de la composante intermédiaire (B). Le seul cas où il y a une structure dominante pour toutes les boucles de contrôle, c'est lorsque l'alimentation contenant de faibles quantités de la composante intermédiaire et le mélange ont la même volatilité relative. La colonne Petlyuk est le choix optimal dans un tel cas, ce qui contredit les attentes générales concernant son comportement de contrôle. En outre, les demandes d'énergie pendant les réponses dynamiques sont significativement plus faibles que celles observées pour les autres séquences de distillation. Ainsi, non seulement les options TCDS sont plus efficaces que les séquences conventionnelles, mais il y a des cas où elles offrent également de meilleures propriétés de contrôle d'asservissement. [source] A direct control scheme based on recurrent fuzzy neural networks for the UPFC series branch,ASIAN JOURNAL OF CONTROL, Issue 6 2009Tsao-Tsung Ma Abstract In this paper, a new control scheme using recurrent fuzzy neural controllers is proposed for the series branch of the unified power flow controller (UPFC) to improve the dynamic performance of real-time power flow control functions with the aim of reducing the inevitable interaction between the real and reactive power flow control parameters. To simplify the theoretical analysis of the coupled dynamics within the UPFC and the controlled power system, the three phase description of a two-bus test power system embedded with a UPFC is transformed into d,q components based on a synchronously rotating reference frame. For control systems with inherent nonlinear coupling features, a feed-forward control scheme based on fuzzy neural controllers is developed to realize the decoupling control objectives. Based on the simulation results, the proposed control scheme is able to overcome the drawbacks of the traditional power flow controllers designed on small disturbance linearizing methods. Comprehensive simulation results on the EMTDC/PSCAD and MATLAB programs are presented and discussed to verify the effectiveness of the proposed control scheme. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source] Decentralized Control for Multivariable Processes with Actuator NonlinearitiesASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1-2 2006S. W. Su Decentralized control is the most widely used control strategy in the process industries because of the simplicity to design and implement the controller, and the potential to achieve failure tolerant control. Actuator nonlinearities are often encountered in many chemical processes. This paper presents a decentralized control method for processes which have static actuator nonlinearities, such as saturation and dead zone. The proposed decentralized integral controller is designed based on feedforward passivation, which can be applied to nonminimum phase processes and/or processes of high relative degree. The concept of marginally stable positive real systems is used to analyse the stability of a closedloop system. The feedforward system is constructed to attain dynamic performance on the basis of frequency based passivity analysis. The effectiveness of the proposed approach is demonstrated using an example of a quadruple tank control problem. [source] | |||||||||||||