WorldWideScience

Sample records for transient dynamic loading

  1. Nonlinear modeling and dynamic analysis of hydro-turbine governing system in the process of load rejection transient

    International Nuclear Information System (INIS)

    Zhang, Hao; Chen, Diyi; Xu, Beibei; Wang, Feifei

    2015-01-01

    Graphical abstract: Nonlinear dynamic transfer coefficients are introduced to the hydro-turbine governing system. In the process of load reject ion transient, the nonlinear dynamical behaviors of the system are studied in detail. - Highlights: • A novel mathematical model of a hydro-turbine governing system is established. • The process of load rejection transient is considered. • Nonlinear dynamic transfer coefficients are introduced to the system. • The bifurcation diagram with the variable t has better engineering significance. • The nonlinear dynamical behaviors of the system are studied in detail. - Abstract: This article pays attention to the mathematical modeling of a hydro-turbine governing system in the process of load rejection transient. As a pioneer work, the nonlinear dynamic transfer coefficients are introduced in a penstock system. Considering a generator system, a turbine system and a governor system, we present a novel nonlinear dynamical model of a hydro-turbine governing system. Fortunately, for the unchanged of PID parameters, we acquire the stable regions of the governing system in the process of load rejection transient by numerical simulations. Moreover, the nonlinear dynamic behaviors of the governing system are illustrated by bifurcation diagrams, Poincare maps, time waveforms and phase orbits. More importantly, these methods and analytic results will present theoretical groundwork for allowing a hydropower station in the process of load rejection transient

  2. Evaluation of dynamic loads induced by transient regimes of fluid flows in the pipe systems and devices of reducing the loads and their effects

    International Nuclear Information System (INIS)

    Serban, Viorel; Chirita, Alexandru Mihai; Androne, Marian; Alexandru, Constantin; Ciuca, Camelia; Badara, Janina; Alexandru, Carmen

    1995-01-01

    The paper presents the analytic methods for estimating the dynamic effects induced in pipe systems in transient regimes. They are based on computation programs developed in order to check the behaviour of ECCS and EWS under 'water hammer effect' and the behaviour of the primary circuit system under stresses caused by pipe cracks. Computation examples are presented in order to emphasize the capabilities of the programs to model transient phenomena in complex pipe networks. The overpressure induced by the water hammer effect, as revealed by comparing several transient regimes, depends on the fluid viscosity, the initial speed, the duration of starting the transient regime, the system rigidity, etc. Values several ten times higher that the initial one could be thus reached. An overview of new types of devices designed for damping the effect of water hammer phenomenon, as well as of sustaining supports for pipe systems and equipment able to damp the vibrations produced by the transient regimes of fluid flows and seismic movements is presented. These devices have also to cope with the high shocks produced by pipe breakage as well as high static loads. The paper contains the following sections: 1. Introduction; 2. Evaluating dynamic loads associated to the water hammer phenomenon; 3. Determining loads associated to the water hammer phenomenon for the ECC system of the Cernavoda NPP Unit 1; 4. Device for reducing the water hammer effects; 5. Evaluating dynamic loads associated to pipe cracks; 6. Determining loads associated to pipe cracks in the Cernavoda NPP primary circuit; 7. Devices for absorbing and damping the dynamic loads in pipe systems and equipment; 8. Conclusions. (authors)

  3. Transient analysis of house load operation for LNPP

    International Nuclear Information System (INIS)

    Shi Junying; Zheng Bin

    2000-01-01

    The author analysis the transient of house load operation for Ling'ao Nuclear Power Plant by using the methods of dynamic simulation and closed loops of primary and secondary system. The transient of house load operation from 100% FP is the most severe that can occur on the unit in normal operation because it causes immediately shedding of 95% of turbine load and requires the unit to operate steadily at reduced power. The results show that the transient can be successful both at beginning of core life and manual house load operation. However, more attentions must be paid to automatic house load operation caused by grid fault at toward end of core life because the success of the transient could be threatened by the actuation of the protection of high flux and high flux rate

  4. Dynamic characteristics of motor-gear system under load saltations and voltage transients

    Science.gov (United States)

    Bai, Wenyu; Qin, Datong; Wang, Yawen; Lim, Teik C.

    2018-02-01

    In this paper, a dynamic model of a motor-gear system is proposed. The model combines a nonlinear permeance network model (PNM) of a squirrel-cage induction motor and a coupled lateral-torsional dynamic model of a planetary geared rotor system. The external excitations including voltage transients and load saltations, as well as the internal excitations such as spatial effects, magnetic circuits topology and material nonlinearity in the motor, and time-varying mesh stiffness and damping in the planetary gear system are considered in the proposed model. Then, the simulation results are compared with those predicted by the electromechanical model containing a dynamic motor model with constant inductances. The comparison showed that the electromechanical system model with the PNM motor model yields more reasonable results than the electromechanical system model with the lumped-parameter electric machine. It is observed that electromechanical coupling effect can induce additional and severe gear vibrations. In addition, the external conditions, especially the voltage transients, will dramatically affect the dynamic characteristics of the electromechanical system. Finally, some suggestions are offered based on this analysis for improving the performance and reliability of the electromechanical system.

  5. On the application of the dynamic plasticity theory for the treatment of reinforced concrete structures under transient loading

    International Nuclear Information System (INIS)

    Ammann, W.

    1983-01-01

    After a short introduction of the theory of dynamic plasticity, the possible applications of this theory on reinforced concrete structures under transient loading are discussed. Estimates can be obtained by relations giving lower and upper limits for dynamically loaded supporting beams. A procedure similar for the mode approximation method is described for the calculation of beams after a sudden failure of a support. (orig.) [de

  6. Static and transient beam loading of a synchrotron

    International Nuclear Information System (INIS)

    Zhang, S.Y.; Weng, W.T.

    1992-01-01

    In a synchrotron, when the beam induced current is comparable to the driver current, the RF cavity is subjected to beam loading perturbation and corrective steps have to be implemented to regain beam stability. In this paper, the static and transient beam loading will be studied. We first discuss the static beam loading, which includes the cavity detuning condition, the stability condition, and the generator power dissipation. The beam current induced beam phase deviation is used as criterion to study the transient beam loading. The upgraded and the old AGS RF system parameters are used as an example to demonstrate how to choose cavity and generator parameters to satisfy the stability requirements under the beam loading. The dynamic models for the beam loading with beam control, and the beam loading with fast power amplifier feedback are presented and analyzed. It is shown that the beam phase and radial feedbacks alone are insufficient for the transient beam loading compensation, but the fast power amplifier feedback can provide effective correction on the beam loading. The limitation of the fast feedback and the beam loading with tuning and AVC loops are also discussed

  7. Dynamic behaviour of mono bucket foundations subjected to combined transient loading

    DEFF Research Database (Denmark)

    Nielsen, Søren Dam; Ibsen, Lars Bo; Nielsen, Benjaminn Nordahl

    2015-01-01

    This article presents the results from small scale testing, investigating the effect of transient combined loading of a bucketfoundation. The tests are performed inside a pressure tank at Aalborg University, Denmark. The bucket foundation was installed in dense water saturated sand and transient ...

  8. Soil-structure interaction for transient loads due to safety relief valve discharges

    International Nuclear Information System (INIS)

    Tseng, W.S.; Tsai, N.C.

    1978-01-01

    Dynamic responses of BWR Mark II containment structures subjected to axisymmetric transient pressure loadings due to simultaneous safety relief valve discharges were investigated using finite element analysis, including the soil-structure interaction effect. To properly consider the soil-structure interaction effect, a simplified lumped parameter foundation model and axisymmetric finite element foundation model with viscous boundary impedance are used. Analytical results are presented to demonstrate the effectiveness of the simplified foundation model and to exhibit the dynamic response behavior of the structure as the transient loading frequency and the foundation rigidity vary. The impact of the dynamic structural response due to this type of loading on the equipment design is also discussed. (Auth.)

  9. EURDYN, Nonlinear Transient Analysis of Structure with Dynamic Loads

    International Nuclear Information System (INIS)

    Donea, J.; Giuliani, S.; Halleux, J.P.

    1987-01-01

    1 - Description of program or function: The EURDYN computer codes are under development at JRC-Ispra since 1973 for the simulation of non- linear dynamic response of fast-reactor components submitted to impulsive loading due to abnormal working conditions. They are thus mainly used in reactor safety analysis but can apply to other fields. Indeed the codes compute the elasto-plastic transient response of 2-D and thin 3-D structures submitted to fast dynamic loading generated by explosions, impacts... and represented by time dependent pressures, concentrated loads and prescribed displacements, or by initial speeds. Two releases of the structural computer codes EURDYN 01 (2-D beams and triangles and axisymmetric conical shells and triangular tori), 02 (axisymmetric and 2-D quadratic iso-parametric elements) and 03 (triangular plate elements) have already been produced in 1976(1) and 1980(2). They include material (elasto-plasticity using the classical flow theory approach) and geometrical (large displacements and rotations treated by a co-rotational technique) nonlinearities. The present version (Release 3) has been completed mid-1982 and is documented in EUR 8357 EN. The new features of Release 3, as compared to the former ones, roughly consist in: - full large strain capability for 9-node iso-parametric elements (EURDYN 02), - generalized array dimensions, - introduction of the radial return algorithm for elasto-plastic material modelling, - extension of the energy check facility to the case of prescribed displacements, - possible interface to a post-processing package including time plot facilities (TPLOT). The theoretical aspects can be found in refs. 2,4,5,6,7,8. 2 - Method of solution: - Finite element space discretization. - Explicit time integration. - Lumped masses. - EURDYN 01: 2-D co-rotational formulation including constant strain triangles (plane or axisymmetric), beams and conical shells, this last element being particularly useful for the study of thin

  10. An overview of optimization of structures subjected to transient loads

    International Nuclear Information System (INIS)

    Kang, Byung Soo; Park, Gyung Jin

    2005-01-01

    Various aspects of structural optimization techniques under transient loads are extensively reviewed. The main themes of the paper are treatment of time dependent constraints, calculation of design sensitivity, and approximation. Each subject is reviewed with the corresponding papers that have been published since 1970s. The treatment of time dependent constraints in both the direct method and the transformation method is discussed. Two ways of calculating design sensitivity of a structure under transient loads are discussed-direct differentiation method and adjoint variable method. The approximation concept mainly focuses on response surface method in crashworthiness and local approximation with the intermediate variable. Especially, as an approximated optimization technique, equivalent static load method which takes advantage of the well-established static response optimization technique is introduced. And as an application area of dynamic response optimization technique, the structural optimization in flexible multibody dynamic system is reviewed in the viewpoint of the above three themes

  11. Transient dynamic finite element analysis of hydrogen distribution test chamber structure for hydrogen combustion loads

    International Nuclear Information System (INIS)

    Singh, R.K.; Redlinger, R.; Breitung, W.

    2005-09-01

    Design and analysis of blast resistant structures is an important area of safety research in nuclear, aerospace, chemical process and vehicle industries. Institute for Nuclear and Energy Technologies (IKET) of Research Centre- Karlsruhe (Forschungszentrum Karlsruhe or FZK) in Germany is pursuing active research on the entire spectrum of safety evaluation for efficient hydrogen management in case of the postulated design basis and beyond the design basis severe accidents for nuclear and non-nuclear applications. This report concentrates on the consequence analysis of hydrogen combustion accidents with emphasis on the structural safety assessment. The transient finite element simulation results obtained for 2gm, 4gm, 8gm and 16gm hydrogen combustion experiments concluded recently on the test-cell structure are described. The frequencies and damping of the test-cell observed during the hammer tests and the combustion experiments are used for the present three dimensional finite element model qualification. For the numerical transient dynamic evaluation of the test-cell structure, the pressure time history data computed with CFD code COM-3D is used for the four combustion experiments. Detail comparisons of the present numerical results for the four combustion experiments with the observed time signals are carried out to evaluate the structural connection behavior. For all the combustion experiments excellent agreement is noted for the computed accelerations and displacements at the standard transducer locations, where the measurements were made during the different combustion tests. In addition inelastic analysis is also presented for the test-cell structure to evaluate the limiting impulsive and quasi-static pressure loads. These results are used to evaluate the response of the test cell structure for the postulated over pressurization of the test-cell due to the blast load generated in case of 64 gm hydrogen ignition for which additional sets of computations were

  12. Development of an Aeroelastic Modeling Capability for Transient Nozzle Side Load Analysis

    Science.gov (United States)

    Wang, Ten-See; Zhao, Xiang; Zhang, Sijun; Chen, Yen-Sen

    2013-01-01

    Lateral nozzle forces are known to cause severe structural damage to any new rocket engine in development during test. While three-dimensional, transient, turbulent, chemically reacting computational fluid dynamics methodology has been demonstrated to capture major side load physics with rigid nozzles, hot-fire tests often show nozzle structure deformation during major side load events, leading to structural damages if structural strengthening measures were not taken. The modeling picture is incomplete without the capability to address the two-way responses between the structure and fluid. The objective of this study is to develop a coupled aeroelastic modeling capability by implementing the necessary structural dynamics component into an anchored computational fluid dynamics methodology. The computational fluid dynamics component is based on an unstructured-grid, pressure-based computational fluid dynamics formulation, while the computational structural dynamics component is developed in the framework of modal analysis. Transient aeroelastic nozzle startup analyses of the Block I Space Shuttle Main Engine at sea level were performed. The computed results from the aeroelastic nozzle modeling are presented.

  13. Dynamic analysis of solid propellant grains subjected to ignition pressurization loading

    Science.gov (United States)

    Chyuan, Shiang-Woei

    2003-11-01

    Traditionally, the transient analysis of solid propellant grains subjected to ignition pressurization loading was not considered, and quasi-elastic-static analysis was widely adopted for structural integrity because the analytical task gets simplified. But it does not mean that the dynamic effect is not useful and could be neglected arbitrarily, and this effect usually plays a very important role for some critical design. In order to simulate the dynamic response for solid rocket motor, a transient finite element model, accompanied by concepts of time-temperature shift principle, reduced integration and thermorheologically simple material assumption, was used. For studying the dynamic response, diverse ignition pressurization loading cases were used and investigated in the present paper. Results show that the dynamic effect is important for structural integrity of solid propellant grains under ignition pressurization loading. Comparing the effective stress of transient analysis and of quasi-elastic-static analysis, one can see that there is an obvious difference between them because of the dynamic effect. From the work of quasi-elastic-static and transient analyses, the dynamic analysis highlighted several areas of interest and a more accurate and reasonable result could be obtained for the engineer.

  14. Transient Three-Dimensional Side Load Analysis of a Film Cooled Nozzle

    Science.gov (United States)

    Wang, Ten-See; Guidos, Mike

    2008-01-01

    Transient three-dimensional numerical investigations on the side load physics for an engine encompassing a film cooled nozzle extension and a regeneratively cooled thrust chamber, were performed. The objectives of this study are to identify the three-dimensional side load physics and to compute the associated aerodynamic side load using an anchored computational methodology. The computational methodology is based on an unstructured-grid, pressure-based computational fluid dynamics formulation, and a transient inlet history based on an engine system simulation. Ultimately, the computational results will be provided to the nozzle designers for estimating of effect of the peak side load on the nozzle structure. Computations simulating engine startup at ambient pressures corresponding to sea level and three high altitudes were performed. In addition, computations for both engine startup and shutdown transients were also performed for a stub nozzle, operating at sea level. For engine with the full nozzle extension, computational result shows starting up at sea level, the peak side load occurs when the lambda shock steps into the turbine exhaust flow, while the side load caused by the transition from free-shock separation to restricted-shock separation comes at second; and the side loads decreasing rapidly and progressively as the ambient pressure decreases. For the stub nozzle operating at sea level, the computed side loads during both startup and shutdown becomes very small due to the much reduced flow area.

  15. Characterization of dynamic loads on the LMFBR rotating shield

    International Nuclear Information System (INIS)

    Morris, E.

    1979-01-01

    The rotating shields structure is a potential weak point of some current designs of primary containment against postulated whole core explosions. The calculation of the effect of transient loads on this structure, resulting from such an explosion, is therefore important in developing a safety case. The transient loads are usually calculated by computer codes such as ASTARTE, SEURBNUK, REXCO or ICECO and the effect of these loads on the structure by a suitable finite element code. Such procedure can be lengthly and costly. The present paper proposed a procedure which allows the consequences of changes in the transient loads, resulting from design changes for example, to be quickly and simply gauged. The load-impulse method of characterizing dynamic response of a structural system is well established. Provided loads with a similar temporal variation are compared, it can be shown that the dynamic response depends on only two features of the load, an average load and a time intregrated load or impulse. The scope of this approach has been extended by Youngdahl who has shown, for structures which deform in a rigid-plastic manner, that complex laoding histories can be equated to a rectangular form of loading, in a precise manner for simple structures and in an approximate manner for more complicated structures. This paper proposes that the failure characteristics of the rotating shields for which extensive plastic deformation is involved, be calculated for rectangular type loadings. The complex transient loadings calculated for various explosions and various changes in the primary vessel design can then be reduced to an equivalent rectangular form and the consequencial response of the shields structure deduced. (orig.)

  16. Experimental investigation of dynamic performance and transient responses of a kW-class PEM fuel cell stack under various load changes

    International Nuclear Information System (INIS)

    Tang Yong; Yuan Wei; Pan Minqiang; Li Zongtao; Chen Guoqing; Li Yong

    2010-01-01

    The dynamic performance is a very important evaluation index of proton exchange membrane (PEM) fuel cells used for real application, which is mostly related with water, heat and gas management. A commercial PEM fuel cell system of Nexa module is employed to experimentally investigate the dynamic behavior and transient response of a PEM fuel cell stack and reveal involved influential factors. Five groups of dynamic tests are conducted and divided into different stage such as start-up, shut-down, step-up load, regular load variation and irregular load variation. It is observed that the external load changes the current output proportionally and reverses stack voltage accordingly. The purge operation benefits performance recovery and enhancement during a constant load and its time strongly depends on the operational current level. Overshoot and undershoot behaviors are observed during transience. But the current undershoot does not appear due to charge double-layer effect. Additionally, magnitudes of the peaks of the voltage overshoot and undershoot vary at different current levels. The operating temperature responds fast to current load but changes slowly showing an arc-like profile without any overshoot and undershoot events. The air flow rate changes directly following the dynamic load demand. But the increased amount of air flow rate during different step-change is not identical, which depends on the requirement of internal reaction and flooding intensity. The results can be utilized for validation of dynamic fuel cell models, and regarded as reference for effective control and management strategies.

  17. Vibrations of composite circular shell structures due to transient loads

    International Nuclear Information System (INIS)

    Schrader, K.-H.; Krutzik, N.; Winkel, G.

    1975-01-01

    Referring to a container consisting of different shell structures - such as spherical, cylindrical and conical shells - the dynamic behavior of coupled spatial shell structures due to transient loads will be investigated. The spatial structure including the filling of water will be idealized as a three-dimensional model consisting of ring elements. The influence of the water filling on the vibrations will be considered by virtual masses added to the shell structures. In circular direction as well as in meridional direction a consistent mass model has been used. By variation of the virtual masses it will be clarified, how these additional masses influence the vibrational behavior of the composed system. Another aspect which will be investigated is the influence of different stiffnesses of substructures or parts of substructures on the natural frequencies, and on their affiliated eigensystems. Furthermore, the maximum and minimum stresses in the structures caused by transient loads acting on the inner surface of the shells will be explored. Here it seems to be possible to locate an area of maximum strain. Rotational loads as well as nonrotational loads will be considered

  18. Static Tensile and Transient Dynamic Response of Cracked Aluminum Plate Repaired with Composite Patch - Numerical Study

    Science.gov (United States)

    Khalili, S. M. R.; Shariyat, M.; Mokhtari, M.

    2014-06-01

    In this study, the central cracked aluminum plates repaired with two sided composite patches are investigated numerically for their response to static tensile and transient dynamic loadings. Contour integral method is used to define and evaluate the stress intensity factors at the crack tips. The reinforcement for the composite patches is carbon fibers. The effect of adhesive thickness and patch thickness and configuration in tensile loading case and pre-tension, pre-compression and crack length effect on the evolution of the mode I stress intensity factor (SIF) (KI) of the repaired structure under transient dynamic loading case are examined. The results indicated that KI of the central cracked plate is reduced by 1/10 to 1/2 as a result of the bonded composite patch repair in tensile loading case. The crack length and the pre-loads are more effective in repaired structure in transient dynamic loading case in which, the 100 N pre-compression reduces the maximum KI for about 40 %, and the 100 N pre-tension reduces the maximum KI after loading period, by about 196 %.

  19. Reconsidering the boundary conditions for a dynamic, transient mode I crack problem

    KAUST Repository

    Leise, Tanya; Walton, Jay; Gorb, Yuliya

    2008-01-01

    . In particular, a transient compressive stress wave travels along the crack faces, moving outward from the loading region on the crack face. This does not occur in the quasistatic or steady state problems, and is a special feature of the transient dynamic problem

  20. Experimental analysis on the dynamic wake of an actuator disc undergoing transient loads

    Science.gov (United States)

    Yu, W.; Hong, V. W.; Ferreira, C.; van Kuik, G. A. M.

    2017-10-01

    The Blade Element Momentum model, which is based on the actuator disc theory, is still the model most used for the design of open rotors. Although derived from steady cases with a fully developed wake, this approach is also applied to unsteady cases, with additional engineering corrections. This work aims to study the impact of an unsteady loading on the wake of an actuator disc. The load and flow of an actuator disc are measured in the Open Jet Facility wind tunnel of Delft University of Technology, for steady and unsteady cases. The velocity and turbulence profiles are characterized in three regions: the inner wake region, the shear layer region and the region outside the wake. For unsteady load cases, the measured velocity field shows a hysteresis effect in relation to the loading, showing differences between the cases when loading is increased and loading is decreased. The flow field also shows a transient response to the step change in loading, with either an overshoot or undershoot of the velocity in relation to the steady-state velocity. In general, a smaller reduced ramp time results in a faster velocity transient, and in turn a larger amplitude of overshoot or undershoot. Time constants analysis shows that the flow reaches the new steady-state slower for load increase than for load decrease; the time constants outside the wake are generally larger than at other radial locations for a given downstream plane; the time constants of measured velocity in the wake show radial dependence.The data are relevant for the validation of numerical models for unsteady actuator discs and wind turbines, and are made available in an open source database (see Appendix).

  1. Dynamic loads on the primary system

    International Nuclear Information System (INIS)

    Rohde, J.

    1980-01-01

    As a result of pipe breaks f.ex. in the primary system of a PWR-plant dynamic forces act on the components of the system as well as on their support-structures and internals. The design basis must guarantee that LOCA or system-transient generated loads cannot produce deformations or fractures that endanger the coolability of the reactor, the emergency feedwater supply to the core-region and a safe shut-down of the reactor. In this lecture the first part of a LOCA will be discussed, where the highest dynamic loads on the primary system are expected. In this connection comments are given on the main assumptions and boundary conditions, the related regulations and guide-lines, as well as the possible consequences of an accident. Next, a review is presented of the analytical methods being used for the determination of thermohydraulic generated loads. The stress-calculations on the basis of these load-functions are discussed in the following lectures. The application of the analytical methods, i.e. the different computer codes, and the verification on the basis of the experimental results are described together with a discussion of the theoretical results. In addition a survey will be given of the research work done in connection with the problems of the dynamic loads under accident conditions. Finally, the problems of the fluid-structure interaction will be explained and comments made on computer code development now under way regarding this problem. A short film will be presented to provide a better understanding of fast transient phenomena. (orig./RW)

  2. Effect of load transients on SOFC operation—current reversal on loss of load

    Science.gov (United States)

    Gemmen, Randall S.; Johnson, Christopher D.

    The dynamics of solid oxide fuel cell (SOFC) operation have been considered previously, but mainly through the use of one-dimensional codes applied to co-flow fuel cell systems. In this paper several geometries are considered, including cross-flow, co-flow, and counter-flow. The details of the model are provided, and the model is compared with some initial experimental data. For parameters typical of SOFC operation, a variety of transient cases are investigated, including representative load increase and decrease and system shutdown. Of particular note for large load decrease conditions (e.g., shutdown) is the occurrence of reverse current over significant portions of the cell, starting from the moment of load loss up to the point where equilibrated conditions again provide positive current. Consideration is given as to when such reverse current conditions might most significantly impact the reliability of the cell.

  3. Study of a spur gear dynamic behavior in transient regime

    Science.gov (United States)

    Khabou, M. T.; Bouchaala, N.; Chaari, F.; Fakhfakh, T.; Haddar, M.

    2011-11-01

    In this paper the dynamic behavior of a single stage spur gear reducer in transient regime is studied. Dynamic response of the single stage spur gear reducer is investigated at different rotating velocities. First, gear excitation is induced by the motor torque and load variation in addition to the fluctuation of meshing stiffness due to the variation of input rotational speed. Then, the dynamic response is computed using the Newmark method. After that, a parameter study is made on spur gear powered in the first place by an electric motor and in the second place by four strokes four cylinders diesel engine. Dynamic responses come to confirm a significant influence of the transient regime on the dynamic behavior of a gear set, particularly in the case of engine acyclism condition.

  4. Reconsidering the boundary conditions for a dynamic, transient mode I crack problem

    KAUST Repository

    Leise, Tanya

    2008-11-01

    A careful examination of a dynamic mode I crack problem leads to the conclusion that the commonly used boundary conditions do not always hold in the case of an applied crack face loading, so that a modification is required to satisfy the equations. In particular, a transient compressive stress wave travels along the crack faces, moving outward from the loading region on the crack face. This does not occur in the quasistatic or steady state problems, and is a special feature of the transient dynamic problem that is important during the time interval immediately following the application of crack face loading. We demonstrate why the usual boundary conditions lead to a prediction of crack face interpenetration, and then examine how to modify the boundary condition for a semi-infinite crack with a cohesive zone. Numerical simulations illustrate the resulting approach.

  5. Experimental investigation of transient thermoelastic effects in dynamic fracture

    International Nuclear Information System (INIS)

    Rittel, D.

    1997-01-01

    Thermoelastic effects in fracture are generally considered to be negligible at the benefit of the conversion of plastic work into heat. For the case of dynamic crack initiation, the experimental and theoretical emphasis has been put on the temperature rise associated with crack-tip plasticity. Nevertheless, earlier experimental work with polymers has shown that thermoelastic cooling precedes the temperature rise at the tip of a propagating crack (Fuller et al., 1975). Transient thermoelastic effects at the tip of a dynamically loaded crack have been theoretically assessed and shown to be significant when thermal conductivity is initially neglected. However, the fundamental question of the relation between crack initiation and thermal fields, both of transient nature, is still open. In this paper, we present an experimental investigation of the thermoelastic effect at the tip of fatigue cracks subjected to mixed-mode (dominant mode 1) dynamic loading. The material is commercial polymethylmethacrylate as an example of 'brittle' material. The applied loads, crack-tip temperatures and fracture time are simultaneously monitored to provide a more complete image of dynamic crack initiation. The corresponding evolution of the stress intensity factors is calculated by a hybrid-experimental numerical model. The results show that substantial crack-tip cooling develops initially to an extent which corroborates theoretical estimates. This effect is followed by a temperature rise. Fracture is shown to initiate during the early cooling phase, thus emphasizing the relevance of the phenomenon to dynamic crack initiation in this material as probably in other materials. (author)

  6. Impact of Load Behavior on Transient Stability and Power Transfer Limitations

    DEFF Research Database (Denmark)

    Gordon, Mark

    2009-01-01

    This paper presents utility based load modeling practices and explores the interaction between loads and the power system and the effect of the interaction on transient stability and power transfer limitations. The effect of load composition is investigated at major load centers together with the......This paper presents utility based load modeling practices and explores the interaction between loads and the power system and the effect of the interaction on transient stability and power transfer limitations. The effect of load composition is investigated at major load centers together...... with the impact on rotor angle excursions of large scale generators during the transient and post-transient period. Responses of multi-induction motor stalling are also considered for different fault clearances in the system. Findings of the investigations carried out on the Eastern Australian interconnected...

  7. Transient Response Dynamic Module Modifications to Include Static and Kinetic Friction Effects

    Science.gov (United States)

    Misel, J. E.; Nenno, S. B.; Takahashi, D.

    1984-01-01

    A methodology that supports forced transient response dynamic solutions when both static and kinetic friction effects are included in a structural system model is described. Modifications that support this type of nonlinear transient response solution are summarized for the transient response dynamics (TRD) NASTRAN module. An overview of specific modifications for the NASTRAN processing subroutines, INITL, TRD1C, and TRD1D, are described with further details regarding inspection of nonlinear input definitions to define the type of nonlinear solution required, along with additional initialization requirements and specific calculation subroutines to successfully solve the transient response problem. The extension of the basic NASTRAN nonlinear methodology is presented through several stages of development to the point where constraint equations and residual flexibility effects are introduced into the finite difference Newmark-Beta recurrsion formulas. Particular emphasis is placed on cost effective solutions for large finite element models such as the Space Shuttle with friction degrees of freedom between the orbiter and payloads mounted in the cargo bay. An alteration to the dynamic finite difference equations of motion is discussed, which allows one to include friction effects at reasonable cost for large structural systems such as the Space Shuttle. Data are presented to indicate the possible impact of transient friction loads to the payload designer for the Space Shuttle. Transient response solution data are also included, which compare solutions without friction forces and those with friction forces for payloads mounted in the Space Shuttle cargo bay. These data indicate that payload components can be sensitive to friction induced loads.

  8. Transient Side Load Analysis of Out-of-Round Film-Cooled Nozzle Extensions

    Science.gov (United States)

    Wang, Ten-See; Lin, Jeff; Ruf, Joe; Guidos, Mike

    2012-01-01

    There was interest in understanding the impact of out-of-round nozzle extension on the nozzle side load during transient startup operations. The out-of-round nozzle extension could be the result of asymmetric internal stresses, deformation induced by previous tests, and asymmetric loads induced by hardware attached to the nozzle. The objective of this study was therefore to computationally investigate the effect of out-of-round nozzle extension on the nozzle side loads during an engine startup transient. The rocket engine studied encompasses a regeneratively cooled chamber and nozzle, along with a film cooled nozzle extension. The computational methodology is based on an unstructured-grid, pressure-based computational fluid dynamics formulation, and transient inlet boundary flow properties derived from an engine system simulation. Six three-dimensional cases were performed with the out-of-roundness achieved by three different degrees of ovalization, elongated on lateral y and z axes: one slightly out-of-round, one more out-of-round, and one significantly out-of-round. The results show that the separation line jump was the primary source of the peak side loads. Comparing to the peak side load of the perfectly round nozzle, the peak side loads increased for the slightly and more ovalized nozzle extensions, and either increased or decreased for the two significantly ovalized nozzle extensions. A theory based on the counteraction of the flow destabilizing effect of an exacerbated asymmetrical flow caused by a lower degree of ovalization, and the flow stabilizing effect of a more symmetrical flow, created also by ovalization, is presented to explain the observations obtained in this effort.

  9. Transient Vibration Prediction for Rotors on Ball Bearings Using Load-dependent Non-linear Bearing Stiffness

    Science.gov (United States)

    Fleming, David P.; Poplawski, J. V.

    2002-01-01

    Rolling-element bearing forces vary nonlinearly with bearing deflection. Thus an accurate rotordynamic transient analysis requires bearing forces to be determined at each step of the transient solution. Analyses have been carried out to show the effect of accurate bearing transient forces (accounting for non-linear speed and load dependent bearing stiffness) as compared to conventional use of average rolling-element bearing stiffness. Bearing forces were calculated by COBRA-AHS (Computer Optimized Ball and Roller Bearing Analysis - Advanced High Speed) and supplied to the rotordynamics code ARDS (Analysis of Rotor Dynamic Systems) for accurate simulation of rotor transient behavior. COBRA-AHS is a fast-running 5 degree-of-freedom computer code able to calculate high speed rolling-element bearing load-displacement data for radial and angular contact ball bearings and also for cylindrical and tapered roller beatings. Results show that use of nonlinear bearing characteristics is essential for accurate prediction of rotordynamic behavior.

  10. Transient and steady-state tests of the space power research engine with resistive and motor loads

    Science.gov (United States)

    Rauch, Jeffrey S.; Kankam, M. David

    1995-01-01

    The NASA Lewis Research Center (LeRC) has been testing free-piston Stirling engine/linear alternators (FPSE/LA) to develop advanced power convertors for space-based electrical power generation. Tests reported herein were performed to evaluate the interaction and transient behavior of FPSE/LA-based power systems with typical user loads. Both resistive and small induction motor loads were tested with the space power research engine (SPRE) power system. Tests showed that the control system could maintain constant long term voltage and stable periodic operation over a large range of engine operating parameters and loads. Modest resistive load changes were shown to cause relatively large voltage and, therefore, piston and displacer amplitude excursions. Starting a typical small induction motor was shown to cause large and, in some cases, deleterious voltage transients. The tests identified the need for more effective controls, if FPSE/LAs are to be used for stand-alone power systems. The tests also generated a large body of transient dynamic data useful for analysis code validation.

  11. Transient and Steady-state Tests of the Space Power Research Engine with Resistive and Motor Loads

    Science.gov (United States)

    Rauch, Jeffrey S.; Kankam, M. David

    1995-01-01

    The NASA Lewis Research Center (LeRC) has been testing free-piston Stirling engine/linear alternators (FPSE/LA) to develop advanced power convertors for space-based electrical power generation. Tests reported herein were performed to evaluate the interaction and transient behavior of FPSE/LA-based power systems with typical user loads. Both resistive and small induction motor loads were tested with the space power research engine (SPRE) power system. Tests showed that the control system could maintain constant long term voltage and stable periodic operation over a large range of engine operating parameters and loads. Modest resistive load changes were shown to cause relatively large voltage and, therefore, piston and displacer amplitude excursions. Starting a typical small induction motor was shown to cause large and, in some cases, deleterious voltage transients. The tests identified the need for more effective controls, if FPSE/LAs are to be used for stand-alone power systems. The tests also generated a large body of transient dynamic data useful for analysis code validation.

  12. Stall/surge dynamics of a multi-stage air compressor in response to a load transient of a hybrid solid oxide fuel cell-gas turbine system

    Science.gov (United States)

    Azizi, Mohammad Ali; Brouwer, Jacob

    2017-10-01

    A better understanding of turbulent unsteady flows in gas turbine systems is necessary to design and control compressors for hybrid fuel cell-gas turbine systems. Compressor stall/surge analysis for a 4 MW hybrid solid oxide fuel cell-gas turbine system for locomotive applications is performed based upon a 1.7 MW multi-stage air compressor. Control strategies are applied to prevent operation of the hybrid SOFC-GT beyond the stall/surge lines of the compressor. Computational fluid dynamics tools are used to simulate the flow distribution and instabilities near the stall/surge line. The results show that a 1.7 MW system compressor like that of a Kawasaki gas turbine is an appropriate choice among the industrial compressors to be used in a 4 MW locomotive SOFC-GT with topping cycle design. The multi-stage radial design of the compressor enhances the ability of the compressor to maintain air flow rate during transient step-load changes. These transient step-load changes are exhibited in many potential applications for SOFC/GT systems. The compressor provides sustained air flow rate during the mild stall/surge event that occurs due to the transient step-load change that is applied, indicating that this type of compressor is well-suited for this hybrid application.

  13. Transient Three-Dimensional Side Load Analysis of Out-of-Round Film Cooled Nozzles

    Science.gov (United States)

    Wang, Ten-See; Lin, Jeff; Ruf, Joe; Guidos, Mike

    2010-01-01

    The objective of this study is to investigate the effect of nozzle out-of-roundness on the transient startup side loads at a high altitude, with an anchored computational methodology. The out-of-roundness could be the result of asymmetric loads induced by hardware attached to the nozzle, asymmetric internal stresses induced by previous tests, and deformation, such as creep, from previous tests. The rocket engine studied encompasses a regeneratively cooled thrust chamber and a film cooled nozzle extension with film coolant distributed from a turbine exhaust manifold. The computational methodology is based on an unstructured-grid, pressure-based computational fluid dynamics formulation, and a transient inlet history based on an engine system simulation. Transient startup computations were performed with the out-of-roundness achieved by four different degrees of ovalization: one perfectly round, one slightly out-of-round, one more out-of-round, and one significantly out-of-round. The results show that the separation-line-jump is the peak side load physics for the round, slightly our-of-round, and more out-of-round cases, and the peak side load increases as the degree of out-of-roundness increases. For the significantly out-of-round nozzle, however, the peak side load reduces to comparable to that of the round nozzle and the separation line jump is not the peak side load physics. The counter-intuitive result of the significantly out-of-round case is found to be related to a side force reduction mechanism that splits the effect of the separation-line-jump into two parts, not only in the circumferential direction and most importantly in time.

  14. Transient beam loading in electron-positron storage rings

    International Nuclear Information System (INIS)

    Wilson, P.B.

    1978-01-01

    In this note the fundamental of transient beam loading in electron-positron storage rings will be reviewed. The notation, and some of the material, has been introduced previously. The present note is, however, more tutorial in nature, and in addition the analysis is extended to include the transient behaviour of the cavity fields and reflected power between bunch passages. Since we are not bound here by the rigid space limitations of a paper for publication, an attempt is made to give a reasonably coherent and complete discussion of transient beam loading that can hopefully be followed even by the uninitiated. The discussion begins with a consideration of the beam-cavity interaction in the ''single-pass'' limit. In this limit it is assumed that the fields induced in the cavity by the passage of a bunch have decayed essentially to zero by the time the next bunch has arrived. The problem of the maximum energy that can be extracted from a cavity by a bunch is given particular attention, since this subject seems to be the source of some confusion. The analysis is then extended to the ''multiple-pass'' case, where the beam-induced fields do not decay to zero between bunches, and to a detailed consideration of the transient variation of cavity fields and reflected power. The note concludes with a brief discussion of the effect of transient beam loading on quantum lifetime

  15. Analysis of transient state in HTS tapes under ripple DC load current

    Science.gov (United States)

    Stepien, M.; Grzesik, B.

    2014-05-01

    The paper concerns the analysis of transient state (quench transition) in HTS tapes loaded with the current having DC component together with a ripple component. Two shapes of the ripple were taken into account: sinusoidal and triangular. Very often HTS tape connected to a power electronic current supply (i.e. superconducting coil for SMES) that delivers DC current with ripples and it needs to be examined under such conditions. Additionally, measurements of electrical (and thermal) parameters under such ripple excitation is useful to tape characterization in broad range of load currents. The results presented in the paper were obtained using test bench which contains programmable DC supply and National Instruments data acquisition system. Voltage drops and load currents were measured vs. time. Analysis of measured parameters as a function of the current was used to tape description with quench dynamics taken into account. Results of measurements were also used to comparison with the results of numerical modelling based on FEM. Presented provisional results show possibility to use results of measurements in transient state to prepare inverse models of superconductors and their detailed numerical modelling.

  16. Quantitative analysis of impact measurements using dynamic load cells

    Directory of Open Access Journals (Sweden)

    Brent J. Maranzano

    2016-03-01

    Full Text Available A mathematical model is used to estimate material properties from a short duration transient impact force measured by dropping spheres onto rectangular coupons fixed to a dynamic load cell. The contact stress between the dynamic load cell surface and the projectile are modeled using Hertzian contact mechanics. Due to the short impact time relative to the load cell dynamics, an additional Kelvin–Voigt element is included in the model to account for the finite response time of the piezoelectric crystal. Calculations with and without the Kelvin–Voigt element are compared to experimental data collected from combinations of polymeric spheres and polymeric and metallic surfaces. The results illustrate that the inclusion of the Kelvin–Voigt element qualitatively captures the post impact resonance and non-linear behavior of the load cell signal and quantitatively improves the estimation of the Young's elastic modulus and Poisson's ratio. Mathematically, the additional KV element couples one additional differential equation to the Hertzian spring-dashpot equation. The model can be numerically integrated in seconds using standard numerical techniques allowing for its use as a rapid technique for the estimation of material properties. Keywords: Young's modulus, Poisson's ratio, Dynamic load cell

  17. Optimization Design of Structures Subjected to Transient Loads Using First and Second Derivatives of Dynamic Displacement and Stress

    Directory of Open Access Journals (Sweden)

    Qimao Liu

    2012-01-01

    Full Text Available This paper developed an effective optimization method, i.e., gradient-Hessian matrix-based method or second order method, of frame structures subjected to the transient loads. An algorithm of first and second derivatives of dynamic displacement and stress with respect to design variables is formulated based on the Newmark method. The inequality time-dependent constraint problem is converted into a sequence of appropriately formed time-independent unconstrained problems using the integral interior point penalty function method. The gradient and Hessian matrixes of the integral interior point penalty functions are also computed. Then the Marquardt's method is employed to solve unconstrained problems. The numerical results show that the optimal design method proposed in this paper can obtain the local optimum design of frame structures and sometimes is more efficient than the augmented Lagrange multiplier method.

  18. Transient Three-Dimensional Analysis of Side Load in Liquid Rocket Engine Nozzles

    Science.gov (United States)

    Wang, Ten-See

    2004-01-01

    Three-dimensional numerical investigations on the nozzle start-up side load physics were performed. The objective of this study is to identify the three-dimensional side load physics and to compute the associated aerodynamic side load using an anchored computational methodology. The computational methodology is based on an unstructured-grid, and pressure-based computational fluid dynamics formulation, and a simulated inlet condition based on a system calculation. Finite-rate chemistry was used throughout the study so that combustion effect is always included, and the effect of wall cooling on side load physics is studied. The side load physics captured include the afterburning wave, transition from free- shock to restricted-shock separation, and lip Lambda shock oscillation. With the adiabatic nozzle, free-shock separation reappears after the transition from free-shock separation to restricted-shock separation, and the subsequent flow pattern of the simultaneous free-shock and restricted-shock separations creates a very asymmetric Mach disk flow. With the cooled nozzle, the more symmetric restricted-shock separation persisted throughout the start-up transient after the transition, leading to an overall lower side load than that of the adiabatic nozzle. The tepee structures corresponding to the maximum side load were addressed.

  19. Use of plant operating history to define transient loads

    International Nuclear Information System (INIS)

    Dwivedy, K.K.

    1996-01-01

    Fatigue and crack growth analyses of components subjected to transient loads have been under continuous development during the recent past to include effects of environment on the components. The accuracy of the evaluation method on the predicted reliability of the components in the operating environment has become a focus of attention. Methods have integrated available material/component test data to improve evaluation techniques. However, in the area of definition of thermal transient loads the analyst still has to remain conservative, because no realistic guidelines have been developed to define thermal transients and their sequences. Fatigue re-evaluations of components are becoming increasingly necessary in operating plants as they age due to two reasons: (1) Components show age related degradation and cannot be repaired/replaced due to economic/logistic reasons. (2) Components experience transient conditions which were not considered in the original design. In either case, the evaluation of remaining life of components involves definition of transients and their sequence from the time the component was put in service until the end of life. As a common practice, initial plant design transients are used in a conservative definition of sequences to obtain results unrealistic for the situation, which sometimes leads to inaccurate estimate of the remaining life of components. The objective of this paper is to use plant operating history and plant monitoring data to provide procedures and techniques to define realistic transients for evaluation

  20. Transient loading of CD34+ hematopoietic progenitor cells with polystyrene nanoparticles.

    Science.gov (United States)

    Deville, Sarah; Hadiwikarta, Wahyu Wijaya; Smisdom, Nick; Wathiong, Bart; Ameloot, Marcel; Nelissen, Inge; Hooyberghs, Jef

    2017-01-01

    CD34 + hematopoietic progenitor cells (HPCs) offer great opportunities to develop new treatments for numerous malignant and non-malignant diseases. Nanoparticle (NP)-based strategies can further enhance this potential, and therefore a thorough understanding of the loading behavior of HPCs towards NPs is essential for a successful application. The present study focusses on the interaction kinetics of 40 nm sized carboxylated polystyrene (PS) NPs with HPCs. Interestingly, a transient association of the NPs with HPCs is observed, reaching a maximum within 1 hour and declining afterwards. This behavior is not seen in dendritic cells (CD34-DCs) differentiated from HPCs, which display a monotonic increase in NP load. We demonstrate that this transient interaction requires an energy-dependent cellular process, suggesting active loading and release of NPs by HPCs. This novel observation offers a unique approach to transiently equip HPCs. A simple theoretical approach modeling the kinetics of NP loading and release is presented, contributing to a framework of describing this phenomenon.

  1. Effect of transient heating loads on beryllium

    International Nuclear Information System (INIS)

    Kupriyanov, Igor B.; Porezanov, Nicolay P.; Nikolaev, Georgyi N.; Kurbatova, Liudmila A.; Podkovyrov, Vyacheslav L.; Muzichenko, Anatoliy D.; Zhitlukhin, Anatoliy M.; Khimchenko, Leonid N.; Gervash, Alexander A.

    2014-01-01

    Highlights: • We study the effect of transient plasma loads on beryllium erosion and surface microstructure. • Beryllium targets were irradiated by plasma streams with energy of 0.5–1 MJ/m 2 at ∼250 °C. • Under plasma loads 0.5–1 MJ/m 2 cracking of beryllium surface is rather slight. • Under 0.5 MJ/m 2 the mass loss of Be is no more than 0.2 g/m 2 shot and decreasing with shots number. • Under 1 MJ/m 2 maximum mass loss of beryllium was 3.7 g/m 2 shot and decreasing with shots number. - Abstract: Beryllium will be used as a plasma facing material for ITER first wall. It is expected that erosion of beryllium under transient plasma loads such as the edge-localized modes (ELMs) and disruptions will mainly determine a lifetime of ITER first wall. The results of recent experiments with the Russian beryllium of TGP-56FW ITER grade on QSPA-Be plasma gun facility are presented. The Be/CuCrZr mock-ups were exposed to upto 100 shots by deuterium plasma streams with pulse duration of 0.5 ms at ∼250 °C and average heat loads of 0.5 and 1 MJ/m 2 . Experiments were performed at 250 °C. The evolution of surface microstructure and cracks morphology as well as beryllium mass loss are investigated under erosion process

  2. Erosion simulation of first wall beryllium armour under ITER transient heat loads

    Science.gov (United States)

    Bazylev, B.; Janeschitz, G.; Landman, I.; Pestchanyi, S.; Loarte, A.

    2009-04-01

    The beryllium is foreseen as plasma facing armour for the first wall in the ITER in form of Be-clad blanket modules in macrobrush design with brush size about 8-10 cm. In ITER significant heat loads during transient events (TE) are expected at the main chamber wall that may leads to the essential damage of the Be armour. The main mechanisms of metallic target damage remain surface melting and melt motion erosion, which determines the lifetime of the plasma facing components. Melting thresholds and melt layer depth of the Be armour under transient loads are estimated for different temperatures of the bulk Be and different shapes of transient loads. The melt motion damages of Be macrobrush armour caused by the tangential friction force and the Lorentz force are analyzed for bulk Be and different sizes of Be-brushes. The damage of FW under radiative loads arising during mitigated disruptions is numerically simulated.

  3. Erosion simulation of first wall beryllium armour under ITER transient heat loads

    Energy Technology Data Exchange (ETDEWEB)

    Bazylev, B. [Forschungszentrum Karlsruhe, IHM, P.O. Box 3640, 76021 Karlsruhe (Germany)], E-mail: bazylev@ihm.fzk.de; Janeschitz, G. [Forschungszentrum Karlsruhe, Fusion, P.O. Box 3640, 76021 Karlsruhe (Germany); Landman, I.; Pestchanyi, S. [Forschungszentrum Karlsruhe, IHM, P.O. Box 3640, 76021 Karlsruhe (Germany); Loarte, A. [ITER Organisation, Cadarache, 13108 Saint Paul Lez Durance Cedex (France)

    2009-04-30

    The beryllium is foreseen as plasma facing armour for the first wall in the ITER in form of Be-clad blanket modules in macrobrush design with brush size about 8-10 cm. In ITER significant heat loads during transient events (TE) are expected at the main chamber wall that may leads to the essential damage of the Be armour. The main mechanisms of metallic target damage remain surface melting and melt motion erosion, which determines the lifetime of the plasma facing components. Melting thresholds and melt layer depth of the Be armour under transient loads are estimated for different temperatures of the bulk Be and different shapes of transient loads. The melt motion damages of Be macrobrush armour caused by the tangential friction force and the Lorentz force are analyzed for bulk Be and different sizes of Be-brushes. The damage of FW under radiative loads arising during mitigated disruptions is numerically simulated.

  4. Erosion simulation of first wall beryllium armour under ITER transient heat loads

    International Nuclear Information System (INIS)

    Bazylev, B.; Janeschitz, G.; Landman, I.; Pestchanyi, S.; Loarte, A.

    2009-01-01

    The beryllium is foreseen as plasma facing armour for the first wall in the ITER in form of Be-clad blanket modules in macrobrush design with brush size about 8-10 cm. In ITER significant heat loads during transient events (TE) are expected at the main chamber wall that may leads to the essential damage of the Be armour. The main mechanisms of metallic target damage remain surface melting and melt motion erosion, which determines the lifetime of the plasma facing components. Melting thresholds and melt layer depth of the Be armour under transient loads are estimated for different temperatures of the bulk Be and different shapes of transient loads. The melt motion damages of Be macrobrush armour caused by the tangential friction force and the Lorentz force are analyzed for bulk Be and different sizes of Be-brushes. The damage of FW under radiative loads arising during mitigated disruptions is numerically simulated.

  5. Transient cognitive dynamics, metastability, and decision making.

    Directory of Open Access Journals (Sweden)

    Mikhail I Rabinovich

    2008-05-01

    Full Text Available The idea that cognitive activity can be understood using nonlinear dynamics has been intensively discussed at length for the last 15 years. One of the popular points of view is that metastable states play a key role in the execution of cognitive functions. Experimental and modeling studies suggest that most of these functions are the result of transient activity of large-scale brain networks in the presence of noise. Such transients may consist of a sequential switching between different metastable cognitive states. The main problem faced when using dynamical theory to describe transient cognitive processes is the fundamental contradiction between reproducibility and flexibility of transient behavior. In this paper, we propose a theoretical description of transient cognitive dynamics based on the interaction of functionally dependent metastable cognitive states. The mathematical image of such transient activity is a stable heteroclinic channel, i.e., a set of trajectories in the vicinity of a heteroclinic skeleton that consists of saddles and unstable separatrices that connect their surroundings. We suggest a basic mathematical model, a strongly dissipative dynamical system, and formulate the conditions for the robustness and reproducibility of cognitive transients that satisfy the competing requirements for stability and flexibility. Based on this approach, we describe here an effective solution for the problem of sequential decision making, represented as a fixed time game: a player takes sequential actions in a changing noisy environment so as to maximize a cumulative reward. As we predict and verify in computer simulations, noise plays an important role in optimizing the gain.

  6. Description of a heat transfer model suitable to calculate transient processes of turbocharged diesel engines with one-dimensional gas-dynamic codes

    Energy Technology Data Exchange (ETDEWEB)

    Galindo, J.; Lujan, J.M.; Serrano, J.R.; Dolz, V. [CMT-Motores Termicos, Universidad Politecnica de Valencia, Valencia (Spain); Guilain, S. [Renault s.a.s., Lardy (France)

    2006-01-15

    This paper describes a heat transfer model to be implemented in a global engine 1-D gas-dynamic code to calculate reciprocating internal combustion engine performance in steady and transient operations. A trade off between simplicity and accuracy has been looked for, in order to fit with the stated objective. To validate the model, the temperature of the exhaust manifold wall in a high-speed direct injection (HSDI) turbocharged diesel engine has been measured during a full load transient. In addition, an indirect assessment of the exhaust gas temperature during this transient process has been carried out. The results show good agreement between the measured and modelled data with good accuracy to predict the engine performance. A dual-walled air gap exhaust manifold has been tested in order to quantify the potential of exhaust gas thermal energy saving on engine transient performance. The experimental results together with the heat transfer model have been used to analyse the influence of thermal energy saving on dynamic performance during the load transient of an HSDI turbocharged diesel engine. (author)

  7. Structural dynamics and fracture mechanics calculations of the behaviour of a DN 425 test piping system subjected to transient loading by water hammer

    International Nuclear Information System (INIS)

    Kussmaul, K.; Kobes, E.; Diem, H.; Schrammel, D.; Brosi, S.

    1994-01-01

    Within the scope of the German HDR safety programme, several tests were carried out to investigate transient pipe loading initiated by a simulated double-ended guillotine break event, and subsequent closure of a feedwater check valve (water hammer, blow-down). Numerical analyses by means of finite element programmes were performed in parallel to the experiments. Using water hammer tests of a DN 425 piping system with predamaged components, the procedure of such analyses will be demonstrated. The results are presented, beginning with structural dynamic calculations of the undamaged piping; followed by coupling of structural dynamics and fracture mechanics computations with simple flaw elements (line spring); and finishing with costly three-dimensional fracture mechanics analyses. A good description of the real piping behaviour can be made by the numerical methods, even in the case of high plastification processes. ((orig.))

  8. An experimental study of the dynamic behavior of a 2 kW proton exchange membrane fuel cell stack under various loading conditions

    International Nuclear Information System (INIS)

    Jian, Qifei; Zhao, Yang; Wang, Haoting

    2015-01-01

    The dynamic behavior of the PEM (proton exchange membrane) fuel cell stack has great effect on the safety and effective operation of its applications. In this paper, a self-designed bulb-array is used to simulate the various loading conditions and study the dynamic behavior of a 2 kW PEM fuel cell stack. An evaluation index, including oscillation rate, pressure variation and dynamic resistance factor, is used to analyze the transient response of the PEM fuel cell stack. It is observed that the stack current increases about 8.6%, and the Oscillation rate decreases more rapidly after activation. In the step-up load stage, the oscillation rate and the dynamic resistance decrease more rapidly as the external load increases. Due to the periodic anodic purge process, a periodic voltage fluctuation can be seen. In addition, when the stack works in the open-loop state (working without the external load), the transient response of the stack current is significantly affected by the hydrogen humidity and the charge double-layer. - Highlights: • The working time of open-loop state significantly affects the transient response. • Oscillation rate decreases faster as the external load increases. • Dynamic resistance factor decreases as the external load increases. • The periodic anodic purge process leads to a slight periodic oscillation of voltage

  9. Aeroelastic Modeling of a Nozzle Startup Transient

    Science.gov (United States)

    Wang, Ten-See; Zhao, Xiang; Zhang, Sijun; Chen, Yen-Sen

    2014-01-01

    Lateral nozzle forces are known to cause severe structural damage to any new rocket engine in development during test. While three-dimensional, transient, turbulent, chemically reacting computational fluid dynamics methodology has been demonstrated to capture major side load physics with rigid nozzles, hot-fire tests often show nozzle structure deformation during major side load events, leading to structural damages if structural strengthening measures were not taken. The modeling picture is incomplete without the capability to address the two-way responses between the structure and fluid. The objective of this study is to develop a tightly coupled aeroelastic modeling algorithm by implementing the necessary structural dynamics component into an anchored computational fluid dynamics methodology. The computational fluid dynamics component is based on an unstructured-grid, pressure-based computational fluid dynamics formulation, while the computational structural dynamics component is developed under the framework of modal analysis. Transient aeroelastic nozzle startup analyses at sea level were performed, and the computed transient nozzle fluid-structure interaction physics presented,

  10. A parallel algorithm for transient solid dynamics simulations with contact detection

    International Nuclear Information System (INIS)

    Attaway, S.; Hendrickson, B.; Plimpton, S.; Gardner, D.; Vaughan, C.; Heinstein, M.; Peery, J.

    1996-01-01

    Solid dynamics simulations with Lagrangian finite elements are used to model a wide variety of problems, such as the calculation of impact damage to shipping containers for nuclear waste and the analysis of vehicular crashes. Using parallel computers for these simulations has been hindered by the difficulty of searching efficiently for material surface contacts in parallel. A new parallel algorithm for calculation of arbitrary material contacts in finite element simulations has been developed and implemented in the PRONTO3D transient solid dynamics code. This paper will explore some of the issues involved in developing efficient, portable, parallel finite element models for nonlinear transient solid dynamics simulations. The contact-detection problem poses interesting challenges for efficient implementation of a solid dynamics simulation on a parallel computer. The finite element mesh is typically partitioned so that each processor owns a localized region of the finite element mesh. This mesh partitioning is optimal for the finite element portion of the calculation since each processor must communicate only with the few connected neighboring processors that share boundaries with the decomposed mesh. However, contacts can occur between surfaces that may be owned by any two arbitrary processors. Hence, a global search across all processors is required at every time step to search for these contacts. Load-imbalance can become a problem since the finite element decomposition divides the volumetric mesh evenly across processors but typically leaves the surface elements unevenly distributed. In practice, these complications have been limiting factors in the performance and scalability of transient solid dynamics on massively parallel computers. In this paper the authors present a new parallel algorithm for contact detection that overcomes many of these limitations

  11. DECREASING OF MECHANISMS DYNAMIC LOADING AT THE TRANSIENT STATE

    Directory of Open Access Journals (Sweden)

    V. S. Loveikin

    2015-11-01

    Full Text Available Purpose. It is necessary to select modes of motion to reduce the dynamic loads in the mechanisms. This choice should be made on optimization basis. The purpose of research is to study methods of synthesis regimes of mechanisms and machines motion that provide optimal modes of movement for terminal and integral criteria. Methodology. For research the one-mass dynamic model of the mechanism has been used. As optimization criteria the terminal and comprehensive integral criteria were used. The stated optimization problem has been solved using dynamic programming and variational calculation. The direct variation method, which allowed finding only approximate solution of the original problem of optimal control, has been used as well. Findings. The ways of ensuring the absolute minimum of terminal criterion have been set for each method of problem solving. The stated characteristics show softness changes of kinematic functions during braking of mechanism. They point to the absolute minimum of adopted terminal criterion in the calculation. Originality. It is necessary to introduce new variables in the system equations during the solving of optimal control problems using dynamic programming to achieve an absolute minimum of terminal criteria. In general, to achieve a minimum of n-order terminal criterion an optimization problem should find relatively (n+1-th order function. When optimization problems is solving by variational calculation in order to ensure a minimization of n-th order terminal criterion by selecting the appropriate boundary conditions, it is necessary to solve the Euler-Poisson 2(n+1-th order equation (subject to symmetric setting boundary conditions. It is a necessary condition for an extremum of the functional with the (n+1-th order integrant. Practical value. Minimizing of adopted terminal criterion in the calculation allows eliminate the brunt in kinematic gearing of mechanisms, which increases their operational life. In addition

  12. Dynamical load factor of impact loaded shell structures

    International Nuclear Information System (INIS)

    Hammel, J.

    1977-01-01

    Dynamical loaded structures can be analysed by spectral representations, which usually lead to an enormous computational effort. If it is possible to find a fitting dynamical load factor, the dynamical problem can be reduced to a statical one. The computation of this statical problem is much simpler. The disadvantage is that the dynamical load factor usually leads to a very rough approximation. In this paper it will be shown, that by combination of these two methods, the approximation of the dynamical load factor can be improved and the consumption of computation time can be enormously reduced. (Auth.)

  13. The Relevance of the Dynamic Stall Effect for Transient

    DEFF Research Database (Denmark)

    Jauch, Clemens; Sørensen, Poul; Bak-Jensen, Birgitte

    2005-01-01

    This article describes a methodology to quantify the influence of dynamic stall on transient fault operations of active-stall turbines. The model of the dynamic stall effect is introduced briefly. The behaviour of the dynamic stall model during a transient fault operation is described mathematica...

  14. Electrical load modeling

    Energy Technology Data Exchange (ETDEWEB)

    Valgas, Helio Moreira; Pinto, Roberto del Giudice R.; Franca, Carlos [Companhia Energetica de Minas Gerais (CEMIG), Belo Horizonte, MG (Brazil); Lambert-Torres, Germano; Silva, Alexandre P. Alves da; Pires, Robson Celso; Costa, Junior, Roberto Affonso [Escola Federal de Engenharia de Itajuba, MG (Brazil)

    1994-12-31

    Accurate dynamic load models allow more precise calculations of power system controls and stability limits, which are critical mainly in the operation planning of power systems. This paper describes the development of a computer program (software) for static and dynamic load model studies using the measurement approach for the CEMIG system. Two dynamic load model structures are developed and tested. A procedure for applying a set of measured data from an on-line transient recording system to develop load models is described. (author) 6 refs., 17 figs.

  15. Site ultrasonic measurement on RPV stud-bolt loading under hot transient of Qinshan NPP

    International Nuclear Information System (INIS)

    Qu Jiadi; Dou Yikang; Zhu Shiming

    1994-08-01

    It expounds that the key of solving thermal transient sealing problem is to obtain the thermal increment of stud-bolt loading. This loading, as a primary stress loading, is directly related to the bolt fatigue life and transient loading spectrum for vessel analysis. The fundamental works and main results of ultrasonic measurement on RPV stud-bolt loading on Qinshan site are also presented. The measuring capability has exceeded 1 m in length and temperature of 280 degree C, therefore, it is possible to be used in the field of NPP. The paper is the continuation of research work for sealing analysis and tests on the RPV (see SMiRT-9, 10)

  16. Transient Three-Dimensional Analysis of Nozzle Side Load in Regeneratively Cooled Engines

    Science.gov (United States)

    Wang, Ten-See

    2005-01-01

    Three-dimensional numerical investigations on the start-up side load physics for a regeneratively cooled, high-aspect-ratio nozzle were performed. The objectives of this study are to identify the three-dimensional side load physics and to compute the associated aerodynamic side load using an anchored computational methodology. The computational methodology is based on an unstructured-grid, pressure-based computational fluid dynamics formulation, and a transient inlet condition based on an engine system simulation. Computations were performed for both the adiabatic and cooled walls in order to understand the effect of boundary conditions. Finite-rate chemistry was used throughout the study so that combustion effect is always included. The results show that three types of shock evolution are responsible for side loads: generation of combustion wave; transitions among free-shock separation, restricted-shock separation, and simultaneous free-shock and restricted shock separations; along with oscillation of shocks across the lip. Wall boundary conditions drastically affect the computed side load physics: the adiabatic nozzle prefers free-shock separation while the cooled nozzle favors restricted-shock separation, resulting in higher peak side load for the cooled nozzle than that of the adiabatic nozzle. By comparing the computed physics with those of test observations, it is concluded that cooled wall is a more realistic boundary condition, and the oscillation of the restricted-shock separation flow pattern across the lip along with its associated tangential shock motion are the dominant side load physics for a regeneratively cooled, high aspect-ratio rocket engine.

  17. Analysis of pile foundations under dynamic loads

    International Nuclear Information System (INIS)

    Waas, G.; Hartmann, H.G.

    1981-01-01

    A method is presented for the analysis of pile foundations which are subjected to horizontal dynamic loads from earthquakes, airplane impact, gas explosion or other sources. The motion of the pile cap and the pile forces are computed. - The loads may be applied to the pile cap or directly to the piles (e.g. by earthquake wave motion). The soil may be stratified and is considered to be an elastic or visco-elastic medium. The piles are assumed vertical. The method makes use of an approximate fundamental solution for displacements caused by a dynamic point load in a layered visco-elastic medium. The approximation involves a discretization of the medium in the vertical direction. In horizontal directions the medium is treated by continuum theory. The soil medium supports each pile at about 10 to 20 nodes. A dynamic flexiblity matrix for the soil is derived which relates the elastic, damping and inertial forces of the soil to the displacements at each node. It includes effects of radiation damping. All piles are coupled through the soil flexibility matrix. The piles are modelled by beam elements. Transient response is computed using fast discrete Fourier transforms. The arrangement of the piles is arbitrary. However, simple and double symmetry can be accounted for by the computer program. When the pile arrangement is axisymmetric, the degrees of freedom can be reduced to only those of two piles per ring. The influence of the number of piles and the influence of the pile spacing on group stiffness and on pile forces is presented for two soil profiles. Dynamic effects on pile forces of a foundation for a reactor building are studied. They are significant when soils are soft. (orig.)

  18. Shock-induced thermal wave propagation and response analysis of a viscoelastic thin plate under transient heating loads

    Science.gov (United States)

    Li, Chenlin; Guo, Huili; Tian, Xiaogeng

    2018-04-01

    This paper is devoted to the thermal shock analysis for viscoelastic materials under transient heating loads. The governing coupled equations with time-delay parameter and nonlocal scale parameter are derived based on the generalized thermo-viscoelasticity theory. The problem of a thin plate composed of viscoelastic material, subjected to a sudden temperature rise at the boundary plane, is solved by employing Laplace transformation techniques. The transient responses, i.e. temperature, displacement, stresses, heat flux as well as strain, are obtained and discussed. The effects of time-delay and nonlocal scale parameter on the transient responses are analyzed and discussed. It can be observed that: the propagation of thermal wave is dynamically smoothed and changed with the variation of time-delay; while the displacement, strain, and stress can be rapidly reduced by nonlocal scale parameter, which can be viewed as an important indicator for predicting the stiffness softening behavior for viscoelastic materials.

  19. The impact of transient thermal loads on beryllium as plasma facing material

    Energy Technology Data Exchange (ETDEWEB)

    Spilker, Benjamin Christof

    2017-01-24

    The rising global energy consumption requires a broad research and development approach in the field of energy technology. Besides renewables, nuclear fusion promises an efficient, CO{sub 2} free, no long-term radioactive waste producing, and safe energy source using only deuterium and lithium as primary resources, which are widely abundant. However, several technical challenges have to be overcome before a nuclear fusion power plant can be built. For this purpose, the experimental reactor ITER is currently under construction in France. ITER is intended to demonstrate the scientific and technological feasibility of net energy generation via nuclear fusion. The most heavily loaded components inside a fusion reactor, which are directly facing the fusion plasma, have to be armoured with well suited materials, which need to be able to withstand the high thermal and particle loads for an economically reasonable lifetime. For ITER, beryllium is chosen as plasma facing material for the largest fraction of the inner vacuum vessel, the so called first wall. Tungsten will be applied in the bottom region of the vacuum vessel, the so called divertor, which acts as the exhaust system of the machine. The choice of beryllium as plasma facing material was driven by its outstanding advantages, e.g. the low atomic number assures that eroded wall material does not strongly decrease the fusion plasma performance, while it combines a high thermal conductivity with low chemical sputtering characteristics. However, the relatively low melting temperature of beryllium of 1287 C comprises the risk of amour damage by melting during transient plasma events, such as edge localized modes or plasma disruptions. Even when mitigated, these events put tremendous power densities in the GW m{sup -2} range with durations in the ms scale onto the plasma facing materials. Hence, the performance of the ITER reference beryllium grade S-65 under transient thermal loads was studied within this work. Thereby

  20. The impact of transient thermal loads on beryllium as plasma facing material

    International Nuclear Information System (INIS)

    Spilker, Benjamin Christof

    2017-01-01

    The rising global energy consumption requires a broad research and development approach in the field of energy technology. Besides renewables, nuclear fusion promises an efficient, CO_2 free, no long-term radioactive waste producing, and safe energy source using only deuterium and lithium as primary resources, which are widely abundant. However, several technical challenges have to be overcome before a nuclear fusion power plant can be built. For this purpose, the experimental reactor ITER is currently under construction in France. ITER is intended to demonstrate the scientific and technological feasibility of net energy generation via nuclear fusion. The most heavily loaded components inside a fusion reactor, which are directly facing the fusion plasma, have to be armoured with well suited materials, which need to be able to withstand the high thermal and particle loads for an economically reasonable lifetime. For ITER, beryllium is chosen as plasma facing material for the largest fraction of the inner vacuum vessel, the so called first wall. Tungsten will be applied in the bottom region of the vacuum vessel, the so called divertor, which acts as the exhaust system of the machine. The choice of beryllium as plasma facing material was driven by its outstanding advantages, e.g. the low atomic number assures that eroded wall material does not strongly decrease the fusion plasma performance, while it combines a high thermal conductivity with low chemical sputtering characteristics. However, the relatively low melting temperature of beryllium of 1287 C comprises the risk of amour damage by melting during transient plasma events, such as edge localized modes or plasma disruptions. Even when mitigated, these events put tremendous power densities in the GW m"-"2 range with durations in the ms scale onto the plasma facing materials. Hence, the performance of the ITER reference beryllium grade S-65 under transient thermal loads was studied within this work. Thereby, the

  1. Transient loading of CD34+ hematopoietic progenitor cells with polystyrene nanoparticles

    Directory of Open Access Journals (Sweden)

    Deville S

    2017-01-01

    Full Text Available Sarah Deville,1,2 Wahyu Wijaya Hadiwikarta,1 Nick Smisdom,1,2 Bart Wathiong,1,3 Marcel Ameloot,2 Inge Nelissen,1 Jef Hooyberghs1,3 1VITO, Flemish Institute for Technological Research, Mol, Belgium; 2Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium; 3Theoretical Physics, Hasselt University, Diepenbeek, Belgium Abstract: CD34+ hematopoietic progenitor cells (HPCs offer great opportunities to develop new treatments for numerous malignant and non-malignant diseases. Nanoparticle (NP-based strategies can further enhance this potential, and therefore a thorough understanding of the loading behavior of HPCs towards NPs is essential for a successful application. The present study focusses on the interaction kinetics of 40 nm sized carboxylated polystyrene (PS NPs with HPCs. Interestingly, a transient association of the NPs with HPCs is observed, reaching a maximum within 1 hour and declining afterwards. This behavior is not seen in dendritic cells (CD34-DCs differentiated from HPCs, which display a monotonic increase in NP load. We demonstrate that this transient interaction requires an energy-dependent cellular process, suggesting active loading and release of NPs by HPCs. This novel observation offers a unique approach to transiently equip HPCs. A simple theoretical approach modeling the kinetics of NP loading and release is presented, contributing to a framework of describing this phenomenon. Keywords: nanoparticles, hematopoietic progenitor cells, dendritic cells, uptake, release

  2. Ultrasonic measurement on RPV stud-bolt loading under hot transient of Qinshan NPP

    International Nuclear Information System (INIS)

    Qu Jiadi; Dou Yikang; Zhu Shiming; Lu Jie; Wang Yingguan

    1994-01-01

    It is a continuation of research work for sealing analysis and tests on the PRV of PWR. It expounds that the key of solving thermal transient sealing problem lies in giving the thermal increment of stud-bolt fatigue life and transient loading spectrum for vessel analysis. The authors recounted the fundamental works and main results of ultrasonic measurement on RPV stud-bolt loading on the reactor of Qinshan Nuclear Power Plant. The measuring capability exceeds 1 m length and 300 degree C temperature. Therefore, it is possible to be used in the field of NPP

  3. Simulation of the transient processes of load rejection under different accident conditions in a hydroelectric generating set

    Science.gov (United States)

    Guo, W. C.; Yang, J. D.; Chen, J. P.; Peng, Z. Y.; Zhang, Y.; Chen, C. C.

    2016-11-01

    Load rejection test is one of the essential tests that carried out before the hydroelectric generating set is put into operation formally. The test aims at inspecting the rationality of the design of the water diversion and power generation system of hydropower station, reliability of the equipment of generating set and the dynamic characteristics of hydroturbine governing system. Proceeding from different accident conditions of hydroelectric generating set, this paper presents the transient processes of load rejection corresponding to different accident conditions, and elaborates the characteristics of different types of load rejection. Then the numerical simulation method of different types of load rejection is established. An engineering project is calculated to verify the validity of the method. Finally, based on the numerical simulation results, the relationship among the different types of load rejection and their functions on the design of hydropower station and the operation of load rejection test are pointed out. The results indicate that: The load rejection caused by the accident within the hydroelectric generating set is realized by emergency distributing valve, and it is the basis of the optimization for the closing law of guide vane and the calculation of regulation and guarantee. The load rejection caused by the accident outside the hydroelectric generating set is realized by the governor. It is the most efficient measure to inspect the dynamic characteristics of hydro-turbine governing system, and its closure rate of guide vane set in the governor depends on the optimization result in the former type load rejection.

  4. Transient Performance of Radiator on Engine Rpm Variation with AC Loading

    Directory of Open Access Journals (Sweden)

    Made Ricki Murti

    2012-11-01

    Full Text Available Radiator is one of heat exchanger applications that has a function to remove out of heat must be able to operate properly for allowed engine temperature limit. Vehicles that operate on the street usually driving with varying rpm so that the heat produced by the combustion process is not constant and then this study analyze the performance of radiators as a function of time (transient condition. Tests is done on the condition of operating the engine with five rpm variations, each for one hour with air conditioning load and without air-conditioning load. The data to be collected includ the inlet and outlet temperature of radiator and radiator fluid volume flow. The results obtained is heat exhausted rate as a performance radiator is increasing as with increasing of engine rpm and at load conditions with the AC produces heat exhausted rate is greater than AC without AC load. The heat exhausted rate in an hour of machine operation still shows the system operates at a transient condition due to there still exists a numerical increase in the heat exhausted rate as a function of time.

  5. Three-dimensional finite element nonlinear dynamic analysis of pile groups for lateral transient and seismic excitations

    International Nuclear Information System (INIS)

    Maheshwari, B.K.; Truman, K.Z.; El Naggar, M.H.; Gould, P.L.

    2004-01-01

    The effects of material nonlinearity of soil and separation at the soil-pile interface on the dynamic behaviour of a single pile and pile groups are investigated. An advanced plasticity-based soil model, hierarchical single surface (HiSS), is incorporated in the finite element formulation. To simulate radiation effects, proper boundary conditions are used. The model and algorithm are verified with analytical results that are available for elastic and elastoplastic soil models. Analyses are performed for seismic excitation and for the load applied on the pile cap. For seismic analysis, both harmonic and transient excitations are considered. For loading on the pile cap, dynamic stiffness of the soil-pile system is derived and the effect of nonlinearity is investigated. The effects of spacing between piles are investigated, and it was found that the effect of soil nonlinearity on the seismic response is very much dependent on the frequency of excitation. For the loading on a pile cap, the nonlinearity increases the response for most of the frequencies of excitation while decreasing the dynamic stiffness of the soil-pile system. (author)

  6. TRANSIENT BEAM LOADING EFFECTS IN RF SYSTEMS IN JLEIC

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Haipeng [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Guo, Jiquan [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Rimmer, Robert A. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Wang, Shaoheng [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2016-05-01

    The pulsed electron bunch trains generated from the Continuous Electron Beam Accelerator Facility (CEBAF) linac to inject into the proposed Jefferson Lab Electron Ion Collider (JLEIC) e-ring will produce transient beam loading effects in the Superconducting Radio Frequency (SRF) systems that, if not mitigated, could cause unacceptably large beam energy deviation in the injection capture, or exceed the energy acceptance of CEBAF’s recirculating arcs. In the electron storage ring, the beam abort or ion clearing gaps or uneven bucket filling can cause large beam phase transients in the (S)RF cavity control systems and even beam loss due to Robinson instability. We have first analysed the beam stability criteria in steady state and estimated the transient effect in Feedforward and Feedback RF controls. Initial analytical models for these effects are shown for the design of the JLEIC e-ring from 3GeV to 12GeV.

  7. Francis-99: Transient CFD simulation of load changes and turbine shutdown in a model sized high-head Francis turbine

    International Nuclear Information System (INIS)

    Mössinger, Peter; Jester-Zürker, Roland; Jung, Alexander

    2017-01-01

    With increasing requirements for hydropower plant operation due to intermittent renewable energy sources like wind and solar, numerical simulations of transient operations in hydraulic turbo machines become more important. As a continuation of the work performed for the first workshop which covered three steady operating conditions, in the present paper load changes and a shutdown procedure are investigated. The findings of previous studies are used to create a 360° model and compare measurements with simulation results for the operating points part load, high load and best efficiency. A mesh motion procedure is introduced, allowing to represent moving guide vanes for load changes from best efficiency to part load and high load. Additionally an automated re-mesh procedure is added for turbine shutdown to ensure reliable mesh quality during guide vane closing. All three transient operations are compared to PIV velocity measurements in the draft tube and pressure signals in the vaneless space. Simulation results of axial velocity distributions for all three steady operation points, during both load changes and for the shutdown correlated well with the measurement. An offset at vaneless space pressure is found to be a result of guide vane corrections for the simulation to ensure similar velocity fields. Short-time Fourier transformation indicating increasing amplitudes and frequencies at speed-no load conditions. Further studies will discuss the already measured start-up procedure and investigate the necessity to consider the hydraulic system dynamics upstream of the turbine by means of a 1D3D coupling between the 3D flow field and a 1D system model. (paper)

  8. Francis-99: Transient CFD simulation of load changes and turbine shutdown in a model sized high-head Francis turbine

    Science.gov (United States)

    Mössinger, Peter; Jester-Zürker, Roland; Jung, Alexander

    2017-01-01

    With increasing requirements for hydropower plant operation due to intermittent renewable energy sources like wind and solar, numerical simulations of transient operations in hydraulic turbo machines become more important. As a continuation of the work performed for the first workshop which covered three steady operating conditions, in the present paper load changes and a shutdown procedure are investigated. The findings of previous studies are used to create a 360° model and compare measurements with simulation results for the operating points part load, high load and best efficiency. A mesh motion procedure is introduced, allowing to represent moving guide vanes for load changes from best efficiency to part load and high load. Additionally an automated re-mesh procedure is added for turbine shutdown to ensure reliable mesh quality during guide vane closing. All three transient operations are compared to PIV velocity measurements in the draft tube and pressure signals in the vaneless space. Simulation results of axial velocity distributions for all three steady operation points, during both load changes and for the shutdown correlated well with the measurement. An offset at vaneless space pressure is found to be a result of guide vane corrections for the simulation to ensure similar velocity fields. Short-time Fourier transformation indicating increasing amplitudes and frequencies at speed-no load conditions. Further studies will discuss the already measured start-up procedure and investigate the necessity to consider the hydraulic system dynamics upstream of the turbine by means of a 1D3D coupling between the 3D flow field and a 1D system model.

  9. Transient beam loading and rf power distribution in the SSC [Superconducting Super Collider

    International Nuclear Information System (INIS)

    Raka, E.C.

    1986-01-01

    Transient beam loading will occur in the SSC at injection as the fifteen individual batches from the High Energy Booster are loaded box-car fashion into the main rings. Periodic transient beam loading will be present also at injection due to the gaps between the successive batches as well as the gap that remains to be filled. Even after the rings have been ''filled'' there will remain the abort gap of 3.1 μsec. This can produce significant modulation of the phase and amplitude of the rf voltage seen by those bunches immediately following it unless corrective measures are taken. Two different methods of reducing this modulation will be discussed, each of which put certain requirements on the rf power distribution system

  10. Transient dynamic crack propagation in gas pressurised pipelines

    International Nuclear Information System (INIS)

    Caldis, E.S.; Owen, D.R.J.; Taylor, C.

    1983-01-01

    The prime limitation of dynamic fracture analysis is the lack of a fundamental crack advance theory which can be easily and economically adopted for use with numerical models. The necessity for the inclusion of inertia effects in the solution of certain problem classes is now evident, but most transient dynamic fracture models considered to date include (of necessity) some intuitive/empirical parameters with a frequent need of a priori knowledge of experimental solutions. The particular problem considered in this study is Mode I transient dynamic crack propagation in gas pressurised pipelines. The steel pipe is modelled using thin shell Semiloof finite elements and its transient response is coupled to a one-dimensional finite element model of the compressible gas equations, incorporating a lateral gas flow parameter. The pipe is governed by the usual dynamic equilibrium equation which is discretised in the time domain by a central difference explicit algorithm. The compressible gas response is modelled by the Continuity and Momentum equations and time discretisation is performed by means of a fully backward difference scheme in time. (orig./GL)

  11. Perturbation analysis of transient population dynamics using matrix projection models

    DEFF Research Database (Denmark)

    Stott, Iain

    2016-01-01

    Non-stable populations exhibit short-term transient dynamics: size, growth and structure that are unlike predicted long-term asymptotic stable, stationary or equilibrium dynamics. Understanding transient dynamics of non-stable populations is important for designing effective population management...... these methods to know exactly what is being measured. Despite a wealth of existing methods, I identify some areas that would benefit from further development....

  12. Dynamic stability under sudden loads

    International Nuclear Information System (INIS)

    Simitses, G.J.

    1998-01-01

    The concept of dynamic stability of elastic structures subjected to sudden (step) loads is discussed. The various criteria and related methodologies for estimating critical conditions are presented with the emphasis on their similarities and differences. These are demonstrated by employing a simple mechanical model. Several structural configurations are analyzed, for demonstration purposes, with the intention of comparing critical dynamic loads to critical static loads. These configurations include shallow arches and shallow spherical caps, two bar frames, and imperfect cylindrical shells of metallic as well as laminated composite construction. In the demonstration examples, the effect of static pre loading on the dynamic critical load is presented

  13. Experimental Simulation of Beryllium Armour Damage Under ITER-like Intense Transient Plasma Loads

    Energy Technology Data Exchange (ETDEWEB)

    Kupriyanov, I.; Basaleev, E.; Nikolaev, G.; Kurbatova, L., E-mail: igkupr@gmail.com [A.A. Bochvar High Technology Research Institute of Inorganic Material, Moscow (Russian Federation); Podkovyrov, V.; Zhitlukhin, A. [SRC RF TRINITI, Troitsk (Russian Federation); Khimchenko, L. L. [Project Centre of ITER, Moscow (Russian Federation)

    2012-09-15

    Full text: Beryllium will be used as a plasma facing material in the next generation of tokamaks such as ITER. During plasma operation in ITER, the plasma facing materials and components will be suffered by different kinds of loading which may affect their surface or their joint to the heat sink. In addition to quasi-stationary loadings which are caused by the normal cycling operation, the plasma facing components and materials may also be exposed to the intense short transient loads like disruptions, ELMs. All these events may lead to beryllium surface melting, cracking, evaporation and erosion. It is expected that the erosion of beryllium under transient plasma loads such as ELMs and disruptions will mainly determine a lifetime of ITER first wall. To obtain the experimental data for the evaluation of the beryllium armor lifetime and dust production under ITER-relevant transient loads, the advanced plasma gun QSPA-Be facility has been constructed in Bochvar Institute. This paper presents recent results of the experiments with Russian beryllium of TGP-56FW ITER grade. The mock-ups of a special design armored with two beryllium targets (80 x 80 x 10 mm{sup 3}) were tested by hydrogen plasma streams (5 cm in diameter) with pulse duration of 0.5 ms and heat load of 0.5 and 1.0 MJ/m{sup 2}. Experiments were performed at RT temperature. The evolution of surface microstructure and profile, cracks morphology and mass loss/gain under erosion process on the beryllium surface exposed to up to 250 shots will be presented and discussed. (author)

  14. Simulation of control performance under house load transients for nuclear power plant

    International Nuclear Information System (INIS)

    Liao Zhongyue; Wang Yuanlong; Tang Yuyuan; Liu Jiong

    1999-01-01

    The CATIA2 code is used to simulate the extreme normal transients--house load transients of Qinshan Phase II 600 MW nuclear power plant. The simulating results show that all of the reactor main parameters are operating in the allowable ranges, the reactor system is stable, and the control characteristics of the nuclear power plant is satisfactory. They are also good in agreement with Framatome's results

  15. Boom or bust? A comparative analysis of transient population dynamics in plants

    DEFF Research Database (Denmark)

    Stott, Iain; Franco, Miguel; Carslake, David

    2010-01-01

    researchers as further possible effectors of complicated dynamics. Previously published methods of transient analysis have tended to require knowledge of initial population structure. However, this has been overcome by the recent development of the parametric Kreiss bound (which describes how large...... a population must become before reaching its maximum possible transient amplification following a disturbance) and the extension of this and other transient indices to simultaneously describe both amplified and attenuated transient dynamics. We apply the Kreiss bound and other transient indices to a data base...... worrying artefact of basic model parameterization. Synthesis. Transient indices describe how big or how small plant populations can get, en route to long-term stable rates of increase or decline. The patterns we found in the potential for transient dynamics, across many species of plants, suggest...

  16. Dynamic analysis of Free-Piston Stirling Engine/Linear Alternator-load system-experimentally validated

    Science.gov (United States)

    Kankam, M. David; Rauch, Jeffrey S.; Santiago, Walter

    1992-01-01

    This paper discusses the effects of variations in system parameters on the dynamic behavior of the Free-Piston Stirling Engine/Linear Alternator (FPSE/LA)-load system. The mathematical formulations incorporate both the mechanical and thermodynamic properties of the FPSE, as well as the electrical equations of the connected load. A state-space technique in the frequency domain is applied to the resulting system of equations to facilitate the evaluation of parametric impacts on the system dynamic stability. Also included is a discussion on the system transient stability as affected by sudden changes in some key operating conditions. Some representative results are correlated with experimental data to verify the model and analytic formulation accuracies. Guidelines are given for ranges of the system parameters which will ensure an overall stable operation.

  17. Belt conveyor dynamics in transient operation for speed control

    OpenAIRE

    He, D.; Pang, Y.; Lodewijks, G.

    2016-01-01

    Belt conveyors play an important role in continuous dry bulk material transport, especially at the mining industry. Speed control is expected to reduce the energy consumption of belt conveyors. Transient operation is the operation of increasing or decreasing conveyor speed for speed control. According to literature review, current research rarely takes the conveyor dynamics in transient operation into account. However, in belt conveyor speed control, the conveyor dynamic behaviors are signifi...

  18. Impact evaluation of conducted UWB transients on loads in power-line networks

    Science.gov (United States)

    Li, Bing; Månsson, Daniel

    2017-09-01

    Nowadays, faced with the ever-increasing dependence on diverse electronic devices and systems, the proliferation of potential electromagnetic interference (EMI) becomes a critical threat for reliable operation. A typical issue is the electronics working reliably in power-line networks when exposed to electromagnetic environment. In this paper, we consider a conducted ultra-wideband (UWB) disturbance, as an example of intentional electromagnetic interference (IEMI) source, and perform the impact evaluation at the loads in a network. With the aid of fast Fourier transform (FFT), the UWB transient is characterized in the frequency domain. Based on a modified Baum-Liu-Tesche (BLT) method, the EMI received at the loads, with complex impedance, is computed. Through inverse FFT (IFFT), we obtain time-domain responses of the loads. To evaluate the impact on loads, we employ five common, but important quantifiers, i.e., time-domain peak, total signal energy, peak signal power, peak time rate of change and peak time integral of the pulse. Moreover, to perform a comprehensive analysis, we also investigate the effects of the attributes (capacitive, resistive, or inductive) of other loads connected to the network, the rise time and pulse width of the UWB transient, and the lengths of power lines. It is seen that, for the loads distributed in a network, the impact evaluation of IEMI should be based on the characteristics of the IEMI source, and the network features, such as load impedances, layout, and characteristics of cables.

  19. Rigid-Plastic Approximations for Predicting Plastic Deformation of Cylindrical Shells Subject to Dynamic Loading

    Directory of Open Access Journals (Sweden)

    Michelle S. Hoo Fatt

    1996-01-01

    Full Text Available A theoretical approach was developed for predicting the plastic deformation of a cylindrical shell subject to asymmetric dynamic loads. The plastic deformation of the leading generator of the shell is found by solving for the transverse deflections of a rigid-plastic beam/string-on-foundation. The axial bending moment and tensile force in the beam/string are equivalent to the longitudinal bending moments and membrane forces of the shell, while the plastic foundation force is equivalent to the shell circumferential bending moment and membrane resistances. Closed-form solutions for the transient and final deformation profile of an impulsive loaded shell when it is in a “string” state were derived using the eigenfunction expansion method. These results were compared to DYNA 3D predictions. The analytical predictions of the transient shell and final centerline deflections were within 25% of the DYNA 3D results.

  20. Damage behavior of REE-doped W-based material exposed to high-flux transient heat loads

    International Nuclear Information System (INIS)

    Shi, Jing; Luo, Lai–Ma; Lin, Jin–shan; Zan, Xiang; Zhu, Xiao–yong; Xu, Qiu; Wu, Yu–Cheng

    2016-01-01

    Pure W and W-Lu alloys were prepared by mechanical alloying (MA) and spark plasma sintering (SPS) technology. The performance and relevant damage mechanism of W-(0%, 2%, 5%, 10%) Lu alloys under transient heat loads were investigated using a laser beam heat load test to simulate the transient events in future nuclear fusion reactors. Scanning electron microscopy was used to observe the morphologies of the damaged surfaces and energy dispersive X-ray spectroscopy was used to conduct composition analysis. Damages to the surface such as cracks, pits, melting layers, Lu-rich droplets, and thermal ablation were observed. A mass of dense fuzz-like nanoparticles formed on the outer region of the laser-exposed area. Recrystallization, grain growth, increased surface roughness, and material erosion were also observed. W-Lu samples with low Lu content demonstrated better thermal performance than pure W, and the degree of damage significantly deteriorated under repetitive transient heat loads.

  1. Impact evaluation of conducted UWB transients on loads in power-line networks

    Directory of Open Access Journals (Sweden)

    B. Li

    2017-09-01

    Full Text Available Nowadays, faced with the ever-increasing dependence on diverse electronic devices and systems, the proliferation of potential electromagnetic interference (EMI becomes a critical threat for reliable operation. A typical issue is the electronics working reliably in power-line networks when exposed to electromagnetic environment. In this paper, we consider a conducted ultra-wideband (UWB disturbance, as an example of intentional electromagnetic interference (IEMI source, and perform the impact evaluation at the loads in a network. With the aid of fast Fourier transform (FFT, the UWB transient is characterized in the frequency domain. Based on a modified Baum–Liu–Tesche (BLT method, the EMI received at the loads, with complex impedance, is computed. Through inverse FFT (IFFT, we obtain time-domain responses of the loads. To evaluate the impact on loads, we employ five common, but important quantifiers, i.e., time-domain peak, total signal energy, peak signal power, peak time rate of change and peak time integral of the pulse. Moreover, to perform a comprehensive analysis, we also investigate the effects of the attributes (capacitive, resistive, or inductive of other loads connected to the network, the rise time and pulse width of the UWB transient, and the lengths of power lines. It is seen that, for the loads distributed in a network, the impact evaluation of IEMI should be based on the characteristics of the IEMI source, and the network features, such as load impedances, layout, and characteristics of cables.

  2. Analysis of the Mannshan Unit 2 full load rejection transient

    International Nuclear Information System (INIS)

    Kang, J.C.; Pei, B.S.; Yu, G.P.; Yuann, R.Y.

    1987-01-01

    Mannshan Unit 2 is a Westinghouse three-loop pressurized water reactor with a rated core power of 2775 MW(thermal) and a rated core flow of 4702 kg/s. Before full power operation, a planned net load rejection was performed during the startup test by opening the main transformer highside breakers. The generator power rapidly reduced to station load. All 16 steam dump valves immediately popped open, and control bank-D rods automatically stepped in as the temperature difference T/sub avg/ - T/sub ref/ reached a programmed 2.8 0 C. Nuclear power decreased smoothly as control rods were inserted into the core. The pressurizer pressure and liquid levels also dropped. Neither safety injection nor reactor trip occurred during this transient. The test was done to verify that the whole system would function properly under a transient to keep the reactor from scramming and that the vessel integrity would also be protected. In this study, which is the preliminary stage of RELAP5/MOD2 transient simulation of the Mannshan PWR plants, system thermal-hydraulic response is tested first and isolated from the neutronic effects. The variation of core power versus time curve was extracted from the power test data to serve as a time varying boundary condition. The comparison of the analytical results of four major parameters (pressurizer pressure, average temperature of the core, steam dump flow rate, and feedwater flow rate) from RELAP5/MOD2 and the power test data is illustrated

  3. Research on the Transient Characteristics of Microgrid with Pulsed Load

    Directory of Open Access Journals (Sweden)

    Jianke Li

    2015-01-01

    Full Text Available Unlike traditional load, pulsed load typically features small average power and large peak power. In this paper, the mathematic models of microgrid consisting of synchronous generator and pulsed load are established. Average Magnitude Difference Compensate Function (AMDCF is proposed to calculate the frequency of synchronous generator, and, based on AMDCF, relative deviation rate (RDR which characterizes the impact of pulsed load on the AC side of grid is firstly defined and this paper describes calculation process in detail. Insulated Gate Bipolar Transistor (IGBT is used as DC switch to control the on/off state of resistive load for simulating pulsed load, the period and duty-cycle of the pulsed load are simulated by setting the gate signal of IGBT, and the peak power of the pulsed load is simulated by setting the resistance. The system dynamic characteristics under pulsed load are analyzed in detail, and the influence of duty-cycle, period, peak power, and filter capacitance of the pulsed load on system dynamic indicators is studied and validated experimentally.

  4. Robust transient dynamics and brain functions

    Directory of Open Access Journals (Sweden)

    Mikhail I Rabinovich

    2011-06-01

    Full Text Available In the last few decades several concepts of Dynamical Systems Theory (DST have guided psychologists, cognitive scientists, and neuroscientists to rethink about sensory motor behavior and embodied cognition. A critical step in the progress of DST application to the brain (supported by modern methods of brain imaging and multi-electrode recording techniques has been the transfer of its initial success in motor behavior to mental function, i.e., perception, emotion, and cognition. Open questions from research in genetics, ecology, brain sciences, etc. have changed DST itself and lead to the discovery of a new dynamical phenomenon, i.e., reproducible and robust transients that are at the same time sensitive to informational signals. The goal of this review is to describe a new mathematical framework -heteroclinic sequential dynamics- to understand self-organized activity in the brain that can explain certain aspects of robust itinerant behavior. Specifically, we discuss a hierarchy of coarse-grain models of mental dynamics in the form of kinetic equations of modes. These modes compete for resources at three levels: (i within the same modality, (ii among different modalities from the same family (like perception, and (iii among modalities from different families (like emotion and cognition. The analysis of the conditions for robustness, i.e., the structural stability of transient (sequential dynamics, give us the possibility to explain phenomena like the finite capacity of our sequential working memory -a vital cognitive function-, and to find specific dynamical signatures -different kinds of instabilities- of several brain functions and mental diseases.

  5. Transient coupled calculations of the Molten Salt Fast Reactor using the Transient Fission Matrix approach

    Energy Technology Data Exchange (ETDEWEB)

    Laureau, A., E-mail: laureau.axel@gmail.com; Heuer, D.; Merle-Lucotte, E.; Rubiolo, P.R.; Allibert, M.; Aufiero, M.

    2017-05-15

    Highlights: • Neutronic ‘Transient Fission Matrix’ approach coupled to the CFD OpenFOAM code. • Fission Matrix interpolation model for fast spectrum homogeneous reactors. • Application for coupled calculations of the Molten Salt Fast Reactor. • Load following, over-cooling and reactivity insertion transient studies. • Validation of the reactor intrinsic stability for normal and accidental transients. - Abstract: In this paper we present transient studies of the Molten Salt Fast Reactor (MSFR). This generation IV reactor is characterized by a liquid fuel circulating in the core cavity, requiring specific simulation tools. An innovative neutronic approach called “Transient Fission Matrix” is used to perform spatial kinetic calculations with a reduced computational cost through a pre-calculation of the Monte Carlo spatial and temporal response of the system. Coupled to this neutronic approach, the Computational Fluid Dynamics code OpenFOAM is used to model the complex flow pattern in the core. An accurate interpolation model developed to take into account the thermal hydraulics feedback on the neutronics including reactivity and neutron flux variation is presented. Finally different transient studies of the reactor in normal and accidental operating conditions are detailed such as reactivity insertion and load following capacities. The results of these studies illustrate the excellent behavior of the MSFR during such transients.

  6. Transient coupled calculations of the Molten Salt Fast Reactor using the Transient Fission Matrix approach

    International Nuclear Information System (INIS)

    Laureau, A.; Heuer, D.; Merle-Lucotte, E.; Rubiolo, P.R.; Allibert, M.; Aufiero, M.

    2017-01-01

    Highlights: • Neutronic ‘Transient Fission Matrix’ approach coupled to the CFD OpenFOAM code. • Fission Matrix interpolation model for fast spectrum homogeneous reactors. • Application for coupled calculations of the Molten Salt Fast Reactor. • Load following, over-cooling and reactivity insertion transient studies. • Validation of the reactor intrinsic stability for normal and accidental transients. - Abstract: In this paper we present transient studies of the Molten Salt Fast Reactor (MSFR). This generation IV reactor is characterized by a liquid fuel circulating in the core cavity, requiring specific simulation tools. An innovative neutronic approach called “Transient Fission Matrix” is used to perform spatial kinetic calculations with a reduced computational cost through a pre-calculation of the Monte Carlo spatial and temporal response of the system. Coupled to this neutronic approach, the Computational Fluid Dynamics code OpenFOAM is used to model the complex flow pattern in the core. An accurate interpolation model developed to take into account the thermal hydraulics feedback on the neutronics including reactivity and neutron flux variation is presented. Finally different transient studies of the reactor in normal and accidental operating conditions are detailed such as reactivity insertion and load following capacities. The results of these studies illustrate the excellent behavior of the MSFR during such transients.

  7. Peak load-impulse characterization of critical pulse loads in structural dynamics

    International Nuclear Information System (INIS)

    Abrahamson, G.R.; Lindberg, H.E.

    1975-01-01

    In presenting the characterization scheme, some general features are described first. A detailed analysis is given for the rigid-plastic system of one degree of freedom to illustrate the calculation of critical load curves in terms of peak load and impulse. This is followed by the presentation of critical load curves for uniformly loaded rigid-plastic beams and plates and for dynamic buckling of cylindrical shells under uniform lateral loads. The peak load-impulse characterization of critical pulse loads is compared with the dynamic load factor characterization, and some aspects of the history of the peak load-pulse scheme are presented. (orig./HP) [de

  8. Pipe rupture and steam/water hammer design loads for dynamic analysis of piping systems

    International Nuclear Information System (INIS)

    Strong, B.R. Jr.; Baschiere, R.J.

    1978-01-01

    The design of restraints and protection devices for nuclear Class I and Class II piping systems must consider severe pipe rupture and steam/water hammer loadings. Limited stress margins require that an accurate prediction of these loads be obtained with a minimum of conservatism in the loads. Methods are available currently for such fluid transient load development, but each method is severely restricted as to the complexity and/or the range of fluid state excursions which can be simulated. This paper presents a general technique for generation of pipe rupture and steam/water hammer design loads for dynamic analysis of nuclear piping systems which does not have the limitations of existing methods. Blowdown thrust loadings and unbalanced piping acceleration loads for restraint design of all nuclear piping systems may be found using this method. The technique allows the effects of two-phase distributed friction, liquid flashing and condensation, and the surrounding thermal and mechanical equipment to be modeled. A new form of the fluid momentum equation is presented which incorporates computer generated fluid acceleration histories by inclusion of a geometry integral termed the 'force equivalent area' (FEA). The FEA values permit the coupling of versatile thermal-hydraulic programs to piping dynamics programs. Typical applications of the method to pipe rupture problems are presented and the resultant load histories compared with existing techniques. (Auth.)

  9. PCNA acts as a stationary loading platform for transiently interacting Okazaki fragment maturation proteins

    Science.gov (United States)

    Sporbert, Anje; Domaing, Petra; Leonhardt, Heinrich; Cardoso, M. Cristina

    2005-01-01

    In DNA replication, the leading strand is synthesized continuously, but lagging strand synthesis requires the complex, discontinuous synthesis of Okazaki fragments, and their subsequent joining. We have used a combination of in situ extraction and dual color photobleaching to compare the dynamic properties of three proteins essential for lagging strand synthesis: the polymerase clamp proliferating cell nuclear antigen (PCNA) and two proteins that bind to it, DNA Ligase I and Fen1. All three proteins are localized at replication foci (RF), but in contrast to PCNA, Ligase and Fen1 were readily extracted. Dual photobleaching combined with time overlays revealed a rapid exchange of Ligase and Fen1 at RF, which is consistent with de novo loading at every Okazaki fragment, while the slow recovery of PCNA mostly occurred at adjacent, newly assembled RF. These data indicate that PCNA works as a stationary loading platform that is reused for multiple Okazaki fragments, while PCNA binding proteins only transiently associate and are not stable components of the replication machinery. PMID:15972794

  10. Transient beam loading in the ALS harmonic RF system

    International Nuclear Information System (INIS)

    Byrd, J.; De Santis, S.; Georgsson, M.; Stover, G.; Fox, J.; Prabhakar, S.; Teytelman, D.

    2000-01-01

    We report on the commissioning of a higher harmonic radiofrequency system at the Advanced Light Source, designed to improve the beam lifetime. We have achieved an increase above a factor of two in our best results up to now. Transient beam loading of the harmonic cavities, due to the unequal fill patterns, creates the greatest limitation on lifetime improvement. We also describe several interesting effects on the operation of the longitudinal and transverse multibunch feedback system

  11. Dynamic Analysis of Load Operations of Two-Stage SOFC Stacks Power Generation System

    Directory of Open Access Journals (Sweden)

    Paulina Pianko-Oprych

    2017-12-01

    Full Text Available The main purpose of this paper was to develop a complete dynamic model of a power generation system based on two serially connected solid oxide fuel cell stacks. The uniqueness of this study lies in a different number of fuel cells in the stacks. The model consists of the electrochemical model, mass and energy balance equations implemented in MATLAB Simulink environment. Particular attention has been paid to the analysis of the transient response of the reformers, fuel cells and the burner. The dynamic behavior of the system during transient conditions was investigated by load step changing. The model evaluates electrical and thermal responses of the system at variable drawn current. It was found that a decrease of 40% in the 1st stage and 2nd solid oxide fuel cell (SOFC stacks drawn current caused both stacks temperature to drop by 2%. An increase of the cell voltage for the 1st and 2nd SOFC stacks led to very fast steam reformer response combined with a slight decrease in reformer temperature, while a considerable burner temperature increase of 70 K can be observed. Predictions of the model provide the basic insight into the operation of the power generation-based SOFC system during various transients and support its further design modifications.

  12. Erosion simulation of first wall beryllium armour under ITER transient heat loads

    Energy Technology Data Exchange (ETDEWEB)

    Bazylev, B.; Janeschitz, G. [Forschungszentrum Karlsruhe GmbH, FZK, Karlsruhe (Germany); Landman, I.; Pestchanyi, S. [FZK-Forschungszentrum Karlsruhe, Association Euratom-FZK, Technik und Umwelt, Karlsruhe (Germany); Loarte, A. [EFDA Close Support Unit Garching, Garching bei Munchen(Germany)

    2007-07-01

    Full text of publication follows: Operation of ITER at high fusion gain is assumed to be the H-mode. A characteristic feature of this regime is the transient release of energy from the confined plasma onto divertor and the first wall by multiple ELMs (about 10{sup 4} ELMs per ITER discharge), which can play a determining role in the erosion rate and lifetime of these components. It is expected that about 50-70 % of the ELM energy releases onto divertor armour and the rest is dumped onto the First Wall (FW) armour. The expected energy heat loads on the ITER divertor and FW during Type I ELM are in range 0.5 - 4 MJ/m{sup 2} in timescales of 0.3-0.6 ms. In case of the ITER disruptions the material evaporated from the divertor expands into the SOL and generates significant radiation heating of the FW armour up to several GW/m2 during a few milliseconds that can also lead to the its melting and noticeable damage. Beryllium macro-brush armour (Be-brushes) is foreseen as plasma FW facing component (PFC) in ITER. During the intense transient events in ITER the surface melting, melt motion, melt splashing and evaporation are seen as the main mechanisms of Be-erosion. The expected erosion of the ITER plasma facing components under transient energy loads can be properly estimated by numerical simulations using the codes MEMOS and PHEMOBRID validated against experimental data obtained at the plasma gun facilities QSPA-T, MK-200UG and QSPA-Kh50 that provide a way to simulate the energy loads expected in ITER in laboratory experiments. The numerical simulations were carried out for the expected ITER ELMs for the heat loads in the range 0.5 - 3.0 MJ/m{sup 2} and the timescale up 0.6 ms and ITER disruptions for the heat loads in the range 2 - 13 MJ/m{sup 2} in timescales of 1-5 ms. Radiation heat loads at the FW armour from the vapour expanded into the SOL were calculated using the codes FOREV-2 and TOKES for both ITER ELM and ITER disruption scenarios. Melt layer damage of the Be

  13. Erosion simulation of first wall beryllium armour under ITER transient heat loads

    International Nuclear Information System (INIS)

    Bazylev, B.; Janeschitz, G.; Landman, I.; Pestchanyi, S.; Loarte, A.

    2007-01-01

    Full text of publication follows: Operation of ITER at high fusion gain is assumed to be the H-mode. A characteristic feature of this regime is the transient release of energy from the confined plasma onto divertor and the first wall by multiple ELMs (about 10 4 ELMs per ITER discharge), which can play a determining role in the erosion rate and lifetime of these components. It is expected that about 50-70 % of the ELM energy releases onto divertor armour and the rest is dumped onto the First Wall (FW) armour. The expected energy heat loads on the ITER divertor and FW during Type I ELM are in range 0.5 - 4 MJ/m 2 in timescales of 0.3-0.6 ms. In case of the ITER disruptions the material evaporated from the divertor expands into the SOL and generates significant radiation heating of the FW armour up to several GW/m2 during a few milliseconds that can also lead to the its melting and noticeable damage. Beryllium macro-brush armour (Be-brushes) is foreseen as plasma FW facing component (PFC) in ITER. During the intense transient events in ITER the surface melting, melt motion, melt splashing and evaporation are seen as the main mechanisms of Be-erosion. The expected erosion of the ITER plasma facing components under transient energy loads can be properly estimated by numerical simulations using the codes MEMOS and PHEMOBRID validated against experimental data obtained at the plasma gun facilities QSPA-T, MK-200UG and QSPA-Kh50 that provide a way to simulate the energy loads expected in ITER in laboratory experiments. The numerical simulations were carried out for the expected ITER ELMs for the heat loads in the range 0.5 - 3.0 MJ/m 2 and the timescale up 0.6 ms and ITER disruptions for the heat loads in the range 2 - 13 MJ/m 2 in timescales of 1-5 ms. Radiation heat loads at the FW armour from the vapour expanded into the SOL were calculated using the codes FOREV-2 and TOKES for both ITER ELM and ITER disruption scenarios. Melt layer damage of the Be FW macro

  14. Model of Transient Process Where Three-Phase Transducer Feeds Induction Motor Equivalent as a Variable Active-Inductive Load

    Directory of Open Access Journals (Sweden)

    Nenad Marković

    2016-01-01

    Full Text Available The paper presents a new approach in the analysis of a transient state in a system where the feeding source is a transducer-IGBT inverter and load is introduced through the induction motor with its R-L parameters. Induction motors with different parameters of powers and power factors are tested. MATLAB simulation of the three-phase inverter that feeds the induction machine has replaced the missing lab equipment with which mathematical model of this system was verified. According to the selected parameters of the inverter and induction machine and through the simulation in the MATLAB program, the results are obtained in the form of diagrams that verify the model of a transient state of the induction machine operation when it operates as a motor which is presented as a variable R-L load. The transient process of the system three-phase bridge inverter whose active-inductive load is the induction machine in the conditions of the change of the load parameters is analyzed. The model of the transient process in the system formed by the inverter in PWM (Pulse Width Modulation converter and induction machine is developed in the time domain and phase coordinates.

  15. Transient heat loads in current fusion experiments, extrapolation to ITER and consequences for its operation

    International Nuclear Information System (INIS)

    Loarte, A; Saibene, G; Sartori, R; Riccardo, V; Andrew, P; Paley, J; Fundamenski, W; Eich, T; Herrmann, A; Pautasso, G; Kirk, A; Counsell, G; Federici, G; Strohmayer, G; Whyte, D; Leonard, A; Pitts, R A; Landman, I; Bazylev, B; Pestchanyi, S

    2007-01-01

    New experimental results on transient loads during ELMs and disruptions in present divertor tokamaks are described and used to carry out a extrapolation to ITER reference conditions and to draw consequences for its operation. In particular, the achievement of low energy/convective type I edge localized modes (ELMs) in ITER-like plasma conditions seems the only way to obtain transient loads which may be compatible with an acceptable erosion lifetime of plasma facing components (PFCs) in ITER. Power loads during disruptions, on the contrary, seem to lead in most cases to an acceptable divertor lifetime because of the relatively small plasma thermal energy remaining at the thermal quench and the large broadening of the power flux footprint during this phase. These conclusions are reinforced by calculations of the expected erosion lifetime, under these load conditions, which take into account a realistic temporal dependence of the power fluxes on PFCs during ELMs and disruptions

  16. Laser re-melting of tungsten damaged by transient heat loads

    Czech Academy of Sciences Publication Activity Database

    Loewenhoff, Th.; Linke, J.; Matějíček, Jiří; Rasinski, M.; Vostřák, M.; Wirtz, M.

    2016-01-01

    Roč. 9, December (2016), s. 165-170 ISSN 2352-1791. [International Conference of Fusion Reactor Material (ICFRM-17) /17./. Aachen, 11.10.2015-16.10.2015] R&D Projects: GA ČR(CZ) GA14-12837S Institutional support: RVO:61389021 Keywords : Plasma facing material * Laser surface remelting * Transient heat load * Tungsten Subject RIV: JG - Metallurgy http://dx.doi.org/10.1016/j.nme.2016.04.004

  17. Dynamic remedial action scheme using online transient stability analysis

    Science.gov (United States)

    Shrestha, Arun

    Economic pressure and environmental factors have forced the modern power systems to operate closer to their stability limits. However, maintaining transient stability is a fundamental requirement for the operation of interconnected power systems. In North America, power systems are planned and operated to withstand the loss of any single or multiple elements without violating North American Electric Reliability Corporation (NERC) system performance criteria. For a contingency resulting in the loss of multiple elements (Category C), emergency transient stability controls may be necessary to stabilize the power system. Emergency control is designed to sense abnormal conditions and subsequently take pre-determined remedial actions to prevent instability. Commonly known as either Remedial Action Schemes (RAS) or as Special/System Protection Schemes (SPS), these emergency control approaches have been extensively adopted by utilities. RAS are designed to address specific problems, e.g. to increase power transfer, to provide reactive support, to address generator instability, to limit thermal overloads, etc. Possible remedial actions include generator tripping, load shedding, capacitor and reactor switching, static VAR control, etc. Among various RAS types, generation shedding is the most effective and widely used emergency control means for maintaining system stability. In this dissertation, an optimal power flow (OPF)-based generation-shedding RAS is proposed. This scheme uses online transient stability calculation and generator cost function to determine appropriate remedial actions. For transient stability calculation, SIngle Machine Equivalent (SIME) technique is used, which reduces the multimachine power system model to a One-Machine Infinite Bus (OMIB) equivalent and identifies critical machines. Unlike conventional RAS, which are designed using offline simulations, online stability calculations make the proposed RAS dynamic and adapting to any power system

  18. A simple dynamic model and transient simulation of the nuclear power reactor on microcomputers

    Energy Technology Data Exchange (ETDEWEB)

    Han, Yang Gee; Park, Cheol [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1998-12-31

    A simple dynamic model is developed for the transient simulation of the nuclear power reactor. The dynamic model includes the normalized neutron kinetics model with reactivity feedback effects and the core thermal-hydraulics model. The main objective of this paper demonstrates the capability of the developed dynamic model to simulate various important variables of interest for a nuclear power reactor transient. Some representative results of transient simulations show the expected trends in all cases, even though no available data for comparison. In this work transient simulations are performed on a microcomputer using the DESIRE/N96T continuous system simulation language which is applicable to nuclear power reactor transient analysis. 3 refs., 9 figs. (Author)

  19. A simple dynamic model and transient simulation of the nuclear power reactor on microcomputers

    Energy Technology Data Exchange (ETDEWEB)

    Han, Yang Gee; Park, Cheol [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1997-12-31

    A simple dynamic model is developed for the transient simulation of the nuclear power reactor. The dynamic model includes the normalized neutron kinetics model with reactivity feedback effects and the core thermal-hydraulics model. The main objective of this paper demonstrates the capability of the developed dynamic model to simulate various important variables of interest for a nuclear power reactor transient. Some representative results of transient simulations show the expected trends in all cases, even though no available data for comparison. In this work transient simulations are performed on a microcomputer using the DESIRE/N96T continuous system simulation language which is applicable to nuclear power reactor transient analysis. 3 refs., 9 figs. (Author)

  20. Study on transient beam loading compensation for China ADS proton linac injector II

    Science.gov (United States)

    Gao, Zheng; He, Yuan; Wang, Xian-Wu; Chang, Wei; Zhang, Rui-Feng; Zhu, Zheng-Long; Zhang, Sheng-Hu; Chen, Qi; Powers, Tom

    2016-05-01

    Significant transient beam loading effects were observed during beam commissioning tests of prototype II of the injector for the accelerator driven sub-critical (ADS) system, which took place at the Institute of Modern Physics, Chinese Academy of Sciences, between October and December 2014. During these tests experiments were performed with continuous wave (CW) operation of the cavities with pulsed beam current, and the system was configured to make use of a prototype digital low level radio frequency (LLRF) controller. The system was originally operated in pulsed mode with a simple proportional plus integral and deviation (PID) feedback control algorithm, which was not able to maintain the desired gradient regulation during pulsed 10 mA beam operations. A unique simple transient beam loading compensation method which made use of a combination of proportional and integral (PI) feedback and feedforward control algorithm was implemented in order to significantly reduce the beam induced transient effect in the cavity gradients. The superconducting cavity field variation was reduced to less than 1.7% after turning on this control algorithm. The design and experimental results of this system are presented in this paper. Supported by National Natural Science Foundation of China (91426303, 11525523)

  1. DYNAMIC LOAD DAMPER MODELING

    Directory of Open Access Journals (Sweden)

    Loktev Aleksey Alekseevich

    2013-01-01

    Full Text Available The authors present their findings associated with their modeling of a dynamic load damper. According to the authors, the damper is to be installed onto a structure or its element that may be exposed to impact, vibration or any other dynamic loading. The damper is composed of paralleled or consecutively connected viscous and elastic elements. The authors study the influence of viscosity and elasticity parameters of the damper produced onto the regular displacement of points of the structure to be protected and onto the regular acceleration transmitted immediately from the damper to the elements positioned below it.

  2. Transient behavior of redox flow battery connected to circuit based on global phase structure

    Science.gov (United States)

    Mannari, Toko; Hikihara, Takashi

    A Redox Flow Battery (RFB) is one of the promising energy storage systems in power grid. An RFB has many advantages such as a quick response, a large capacity, and a scalability. Due to these advantages, an RFB can operate in mixed time scale. Actually, it has been demonstrated that an RFB can be used for load leveling, compensating sag, and smoothing the output of the renewable sources. An analysis on transient behaviors of an RFB is a key issue for these applications. An RFB is governed by electrical, chemical, and fluid dynamics. The hybrid structure makes the analysis difficult. To analyze transient behaviors of an RFB, the exact model is necessary. In this paper, we focus on a change in a concentration of ions in the electrolyte, and simulate the change with a model which is mainly based on chemical kinetics. The simulation results introduces transient behaviors of an RFB in a response to a load variation. There are found three kinds of typical transient behaviors including oscillations. As results, it is clarified that the complex transient behaviors, due to slow and fast dynamics in the system, arise by the quick response to load.

  3. Consideration of loading conditions initiated by thermal transients in PWR pressure vessels

    International Nuclear Information System (INIS)

    Azodi; Glahn; Kersting; Schulz; Jansky.

    1983-01-01

    This report describes the present state of PWR-plants in the Federal Republic of Germany with respect to - the design of the primary pressure boundary - the analysis of thermal transients and resulting loads - the material conditions and neutron fluence - the requirements for protection against fast fracture. The experimental and analytical research and development programs are delineated together with some foreign R and D programs. It is shown that the parameters investigated (loading condition, crack shape and orientation etc.) cover a broad range. Extensive analytical investigations are emphasized. (orig./RW) [de

  4. Recrystallization and grain growth induced by ELMs-like transient heat loads in deformed tungsten samples

    Science.gov (United States)

    Suslova, A.; El-Atwani, O.; Sagapuram, D.; Harilal, S. S.; Hassanein, A.

    2014-11-01

    Tungsten has been chosen as the main candidate for plasma facing components (PFCs) due to its superior properties under extreme operating conditions in future nuclear fusion reactors such as ITER. One of the serious issues for PFCs is the high heat load during transient events such as ELMs and disruption in the reactor. Recrystallization and grain size growth in PFC materials caused by transients are undesirable changes in the material, since the isotropic microstructure developed after recrystallization exhibits a higher ductile-to-brittle transition temperature which increases with the grain size, a lower thermal shock fatigue resistance, a lower mechanical strength, and an increased surface roughening. The current work was focused on careful determination of the threshold parameters for surface recrystallization, grain growth rate, and thermal shock fatigue resistance under ELM-like transient heat events. Transient heat loads were simulated using long pulse laser beams for two different grades of ultrafine-grained tungsten. It was observed that cold rolled tungsten demonstrated better power handling capabilities and higher thermal stress fatigue resistance compared to severely deformed tungsten. Higher recrystallization threshold, slower grain growth, and lower degree of surface roughening were observed in the cold rolled tungsten.

  5. Thermodynamic diagnosis of diesel and biodiesel combustion processes during load-increase transient sequences

    International Nuclear Information System (INIS)

    Armas, Octavio; Ballesteros, Rosario; Cardenas, María Dolores

    2012-01-01

    Highlights: ► Thermodynamic diagnosis was applied to diesel combustion process during transient operation. ► Comparative analysis of thermodynamic results with different biodiesel fuels has been carried out. ► Biodiesel fuels studied have a slight effect on timing of the combustion process. ► Methodology used can be applied to improve engine control when using different alternative fuels. -- Abstract: The study of the diesel combustion process is a current topic by the need of thermal efficiency improving and the reduction of pollutant emissions. This circumstance has forced researchers and manufacturers to optimize this process not only in steady state operating conditions but also during transient operation. A zero dimensional thermodynamic diagnostic model, with three species (air, fuel evaporated and burned products), has been used to characterize the combustion process during load increase transient sequences at two different engine speed. In both sequences, three variables were studied: the valve position of the exhaust gas recirculation (EGR), the elapsed time of the transition process and the type of fuel. Three biodiesel fuels were tested pure: rapeseed, soybean and sunflower which were compared to a commercial diesel fuel used as reference. Results are presented comparing the in-cylinder average maximum pressure and temperature, and the phasing of the combustion process based on the calculation of heat release. This study has allowed the detection of the effect of the tested engine parameters and the biodiesel fuels used on the in-cylinder thermodynamic conditions during the load transient sequences studied.

  6. Local Dynamic Stability Associated with Load Carrying

    Directory of Open Access Journals (Sweden)

    Jian Liu

    2013-03-01

    Conclusion: Current study confirmed the sensitivity of local dynamic stability measure in load carrying situation. It was concluded that load carrying tasks were associated with declined local dynamic stability, which may result in increased risk of fall accident. This finding has implications in preventing fall accidents associated with occupational load carrying.

  7. INTRANS. A computer code for the non-linear structural response analysis of reactor internals under transient loads

    International Nuclear Information System (INIS)

    Ramani, D.T.

    1977-01-01

    The 'INTRANS' system is a general purpose computer code, designed to perform linear and non-linear structural stress and deflection analysis of impacting or non-impacting nuclear reactor internals components coupled with reactor vessel, shield building and external as well as internal gapped spring support system. This paper describes in general a unique computational procedure for evaluating the dynamic response of reactor internals, descretised as beam and lumped mass structural system and subjected to external transient loads such as seismic and LOCA time-history forces. The computational procedure is outlined in the INTRANS code, which computes component flexibilities of a discrete lumped mass planar model of reactor internals by idealising an assemblage of finite elements consisting of linear elastic beams with bending, torsional and shear stiffnesses interacted with external or internal linear as well as non-linear multi-gapped spring support system. The method of analysis is based on the displacement method and the code uses the fourth-order Runge-Kutta numerical integration technique as a basis for solution of dynamic equilibrium equations of motion for the system. During the computing process, the dynamic response of each lumped mass is calculated at specific instant of time using well-known step-by-step procedure. At any instant of time then, the transient dynamic motions of the system are held stationary and based on the predicted motions and internal forces of the previous instant. From which complete response at any time-step of interest may then be computed. Using this iterative process, the relationship between motions and internal forces is satisfied step by step throughout the time interval

  8. Transient Stability Improvement for Combined Heat and Power System Using Load Shedding

    Directory of Open Access Journals (Sweden)

    Hung-Cheng Chen

    2014-01-01

    Full Text Available The purpose of the paper is to analyze and improve the transient stability of an industrial combined heat and power (CHP system in a high-tech science park in Taiwan. The CHP system installed two 161 kV/161 kV high-impendence transformers to connect with Taipower System (TPS for both decreasing the short-circuit fault current and increasing the fault critical clearing time. The transient stabilities of three types of operation modes in CHP units, 3G1S, 2G1S, and 1G1S, are analyzed. Under the 3G1S operation mode, the system frequency is immediately restored to 60 Hz after tie line tripping with the TPS. Under the 1G1S and 2G1S operation modes, the system frequencies will continuously decrease and eventually become unstable. A novel transient stability improvement approach using load shedding technique based on the change in frequency is proposed to improve the transient stability.

  9. Methodology used to calculate moderator-system heat load at full power and during reactor transients in CANDU reactors

    International Nuclear Information System (INIS)

    Aydogdu, K.

    1998-01-01

    Nine components determine the moderator-system heat load during full-power operation and during a reactor power transient in a CANDU reactor. The components that contribute to the total moderator-system heat load at any time consist of the heat generated in the calandria tubes, guide tubes and reactivity mechanisms, moderator and reflector; the heat transferred from calandria shell, the inner tubesheets and the fuel channels; and the heat gained from moderator pumps and heat lost from piping. The contributions from each of these components will vary with time during a reactor transient. The sources of heat that arise from the deposition of nuclear energy can be divided into two categories, viz., a) the neutronic component (which is directly proportional to neutronic power), which includes neutron energy absorption, prompt-fission gamma absorption and capture gamma absorption; and b) the fission-product decay-gamma component, which also varies with time after initiation of the transient. An equation was derived to calculate transient heat loads to the moderator. The equation includes two independent variables that are the neutronic power and fission-product decay-gamma power fractions during the transient and a constant term that represents the heat gained from moderator pumps and heat lost from piping. The calculated heat load in the moderator during steady-state full-power operation for a CANDU 6 reactor was compared with available measurements from the Point Lepreau, Wolsong 1 and Gentilly-2 nuclear generating stations. The calculated and measured values were in reasonably good agreement. (author)

  10. Laser spectroscopy and dynamics of transient species

    Energy Technology Data Exchange (ETDEWEB)

    Clouthier, D.J. [Univ. of Kentucky, Lexington (United States)

    1993-12-01

    The goal of this program is to study the vibrational and electronic spectra and excited state dynamics of a number of transient sulfur and oxygen species. A variety of supersonic jet techniques, as well as high resolution FT-IR and intracavity dye laser spectroscopy, have been applied to these studies.

  11. Cognitive Load Theory and the Effects of Transient Information on the Modality Effect

    Science.gov (United States)

    Leahy, Wayne; Sweller, John

    2016-01-01

    Based on cognitive load theory and the "transient information effect," this paper investigated the "modality effect" while interpreting a contour map. The length and complexity of auditory and visual text instructions were manipulated. Experiment 1 indicated that longer audio text information within a presentation was inferior…

  12. Transient analysis for a system with a tilted disc check valve

    International Nuclear Information System (INIS)

    Jeung, Jaesik; Lee, Kyukwang; Cho, Daegwan

    2014-01-01

    Check valves are used to prevent reverse flow conditions in a variety of systems in nuclear power plants. When a check valve is closed by a reverse flow, the transient load can jeopardize the structural integrity on the piping system and its supports. It may also damage intended function of the in-line components even though the severity of the load differs and depends strongly on types of the check valves. To incorporate the transient load in the piping system, it is very important to properly predict the system response to transients such as a check valve closure accompanied by pump trip and to evaluate the system transient. The one-dimensional transient simulation codes such as the RELAP5/MOD3.3 and TRACE were used. There has not been a single model that integrates the two codes to handle the behavior of a tilted disc check valve, which is designed to mitigate check valve slams by shorting the travel of the disc. In this paper a model is presented to predict the dynamic motion of a tilted disc check valve in the transient simulation using the RELAP5/MOD3.3 code and the model is incorporated in a system transient analysis using control variables of the code. In addition, transient analysis for Essential Service Water (ESW) system is performed using the proposed model and the associated load is evaluated for the system. (author)

  13. Erosion of beryllium under ITER - Relevant transient plasma loads

    Science.gov (United States)

    Kupriyanov, I. B.; Nikolaev, G. N.; Kurbatova, L. A.; Porezanov, N. P.; Podkovyrov, V. L.; Muzichenko, A. D.; Zhitlukhin, A. M.; Gervash, A. A.; Safronov, V. M.

    2015-08-01

    Beryllium will be used as a armor material for the ITER first wall. It is expected that erosion of beryllium under transient plasma loads such as the edge-localized modes (ELMs) and disruptions will mainly determine a lifetime of the ITER first wall. This paper presents the results of recent experiments with the Russian beryllium of TGP-56FW ITER grade on QSPA-Be plasma gun facility. The Be/CuCrZr mock-ups were exposed to up to 100 shots by deuterium plasma streams (5 cm in diameter) with pulse duration of 0.5 ms and heat loads range of 0.2-0.5 MJ/m2 at different temperature of beryllium tiles. The temperature of Be tiles has been maintained about 250 and 500 °C during the experiments. After 10, 40 and 100 shots, the beryllium mass loss/gain under erosion process were investigated as well as evolution of surface microstructure and cracks morphology.

  14. Excited-State Dynamics of Carotenoids Studied by Femtosecond Transient Absorption Spectroscopy

    International Nuclear Information System (INIS)

    Lee, Ingu; Pang, Yoonsoo; Lee, Sebok

    2014-01-01

    Carotenoids, natural antenna pigments in photosynthesis share a symmetric backbone of conjugated polyenes. Contrary to the symmetric and almost planar geometries of carotenoids, excited state structure and dynamics of carotenoids are exceedingly complex. In this paper, recent infrared and visible transient absorption measurements and excitation dependent dynamics of 8'-apo-β-caroten-8'-al and 7',7'-dicyano-7'-apo-β-carotene will be reviewed. The recent visible transient absorption measurements of 8'-apo-β-caroten-8'-al in polar and nonpolar solvents will also be introduced to emphasize the complex excited-state dynamics and unsolved problems in the S 2 and S 1 excited states

  15. An Investigation of dynamic characteristics of structures subjected to dynamic load from the viewpoint of design

    International Nuclear Information System (INIS)

    Lee, Hyun Ah; Kim, Yong Il; Park, Gyung Jin; Kang, Byung Soo; Kim, Joo Sung

    2006-01-01

    All the loads in the real world are dynamic loads and structural optimization under dynamic loads is very difficult. Thus the dynamic loads are often transformed to static loads by dynamic factors, which are believed equivalent to the dynamic loads. However, due to the difference of load characteristics, there can be considerable differences between the results from static and dynamic analyses. When the natural frequency of a structure is high, the dynamic analysis result is similar to that of static analysis due to the small inertia effect on the behavior of the structure. However, if the natural frequency of the structure is low, the inertia effect should not be ignored. then, the behavior of the dynamic system is different from that of the static system. The difference of the two cases can be explained from the relationship between the homogeneous and the particular solutions of the differential equation that governs the behavior of the structure. Through various examples, the difference between the dynamic analysis and the static analysis are shown. Also dynamic response optimization results are compared with the results with static loads transformed from dynamic loads by dynamic factors, which show the necessity of the design considering dynamic loads

  16. Introduction to the Explicit Finite Element Method for Nonlinear Transient Dynamics

    CERN Document Server

    Wu, Shen R

    2012-01-01

    A systematic introduction to the theories and formulations of the explicit finite element method As numerical technology continues to grow and evolve with industrial applications, understanding the explicit finite element method has become increasingly important, particularly in the areas of crashworthiness, metal forming, and impact engineering. Introduction to the Explicit FiniteElement Method for Nonlinear Transient Dynamics is the first book to address specifically what is now accepted as the most successful numerical tool for nonlinear transient dynamics. The book aids readers in master

  17. The effects of air stoichiometry and air excess ratio on the transient response of a PEMFC under load change conditions

    International Nuclear Information System (INIS)

    Kim, Bosung; Cha, Dowon; Kim, Yongchan

    2015-01-01

    Highlights: • Effects of controlling parameters on the transient response of a PEMFC are studied. • The transient response is measured by varying air stoichiometry and air excess ratio. • Voltage drop, undershoot, and voltage fluctuation are analyzed under the load change. • Optimal air stoichiometry and air excess ratio are suggested for stable operation. - Abstract: The transient response of a proton exchange membrane fuel cell (PEMFC) is an important issue for transportation applications. The objective of this study is to investigate the effects of operating and controlling parameters on the transient response of a PEMFC for achieving more stable cell performance under load change conditions. The transient response of a PEMFC was measured and analyzed by varying air stoichiometry, air humidity, and air excess ratio (AER). The optimal air stoichiometry and AER were determined to minimize the voltage drop, undershoot, and voltage fluctuation under the load change, while maintaining high cell performance. Based on the present data, the optimal air stoichiometry was determined to be between 2.0 and 2.5, and the optimal AER was suggested to be between 1.65 and 2.0

  18. Dynamic response of a clamped/free hollow circular cylinder under travelling torsional impact loads

    International Nuclear Information System (INIS)

    Jonker, J.B.

    1982-01-01

    Impact-induced vibrations in the casing of a gas centriguge due to a sudden failure of the spinning rotor (crash) can cause structural disintegrity of the casing. In order to study the influence of the rotor failure bahaviour and the impact load histories on the dynamic response of the casing, a simple crash model is proposed in this paper to analyse the transient torsional response due to tangential components of the impact loads. The casing is modeled as a linear-elastic hollow circular cylinder, clamped at the lower end and free at the upper end. The rotor is thought to breakup in identical sections in a sequence determined by its fracture behaviour. Each section is assumed to cause an axi-symmetric load distribution at the inner surface of the casing. Therefore the problem is essentially reduced to the analysis of a clamped/free cylinder under travelling torsional impact loads. The problem is solved by representing the impact loads as local pulses acting over the length of the sections. A perturbation method is used to show that the general two-dimensional theory of axi-symmetric torsional wave propagation in circular cylinders, for the problem under consideration, may be approximated by the elementary one-dimensional theory. Solutions are obtained according to the usual modal expansion approach. Measurements of transient torsional responses are shown to be in good agreement with the calculated responses by choosing a suitable shape of the pulses. The effects of travelling velocity and pulse shape are investigated. Finally the transfer of kinetic energy in the rotor to vibrational energy of torsion in the casing is studied. (orig.)

  19. ORTAP: a nuclear steam supply system simulation for the dynamic analysis of high temperature gas cooled reactor transients

    International Nuclear Information System (INIS)

    Cleveland, J.C.; Hedrick, R.A.; Ball, S.J.; Delene, J.G.

    1977-01-01

    ORTAP was developed to predict the dynamic behavior of the high temperature gas cooled reactor (HTGR) Nuclear Steam Supply System for normal operational transients and postulated accident conditions. It was developed for the Nuclear Regulatory Commission (NRC) as an independent means of obtaining conservative predictions of the transient response of HTGRs over a wide range of conditions. The approach has been to build sufficient detail into the component models so that the coupling between the primary and secondary systems can be accurately represented and so that transients which cover a wide range of conditions can be simulated. System components which are modeled in ORTAP include the reactor core, a typical reheater and steam generator module, a typical helium circulator and circulator turbine and the turbine generator plant. The major plant control systems are also modeled. Normal operational transients which can be analyzed with ORTAP include reactor start-up and shutdown, normal and rapid load changes. Upset transients which can be analyzed with ORTAP include reactor trip, turbine trip and sudden reduction in feedwater flow. ORTAP has also been used to predict plant response to emergency or faulted conditions such as primary system depressurization, loss of primary coolant flow and uncontrolled removal of control poison from the reactor core

  20. Ultrafast carrier dynamics of titanic acid nanotubes investigated by transient absorption spectroscopy.

    Science.gov (United States)

    Wang, Li; Zhao, Hui; Pan, Lin Yun; Weng, Yu Xiang; Nakato, Yoshihiro; Tamai, Naoto

    2010-12-01

    Carrier dynamics of titanic acid nanotubes (phase of H2Ti2O5.H2O) deposited on a quartz plate was examined by visible/near-IR transient absorption spectroscopy with an ultraviolet excitation. The carrier dynamics of titanic acid nanotubes follows the fast trapping process which attributed to the intrinsic tubular structure, the relaxation of shallow trapped carriers and the recombination as a second-order kinetic process. Transient absorption of titanic acid nanotubes was dominated by the absorption of surface-trapped holes in visible region around 500 nm, which was proved by the faster decay dynamics in the presence of polyvinyl alcohol as a hole-scavenger. However, the slow relaxation of free carriers was much more pronounced in the TiO2 single crystals, as compared with the transient absorption spectra of titanic acid nanotubes under the similar excitation.

  1. Numerical analysis of power system transients and dynamics

    CERN Document Server

    Ametani, Akihiro

    2015-01-01

    This book describes the three major power system transient and dynamics simulation tools based on a circuit-theory based approach which are most widely used all over the world (EMTP-ATP, EMTP-RV and EMTDC/PSCAD), together with other powerful simulation tools such as XTAP.

  2. Steady State Dynamic Operating Behavior of Universal Motor

    Directory of Open Access Journals (Sweden)

    Muhammad Khan Burdi

    2015-01-01

    Full Text Available A detailed investigation of the universal motor is developed and used for various dynamic steady state and transient operating conditions of loads. In the investigation, output torque, motor speed, input current, input/output power and efficiency are computed, compared and analyzed for different loads. While this paper discusses the steady-state behavior of the universal motor, another companion paper, ?Transient dynamic behavior of universal motor?, will discuss its transient behavior in detail. A non-linear generalized electric machine model of the motor is considered for the analysis. This study was essential to investigate effect of output load on input current, power, speed and efficiency of the motor during operations. Previously such investigation is not known

  3. The effect of loading time on flexible pavement dynamic response: a finite element analysis

    Science.gov (United States)

    Yin, Hao; Solaimanian, Mansour; Kumar, Tanmay; Stoffels, Shelley

    2007-12-01

    Dynamic response of asphalt concrete (AC) pavements under moving load is a key component for accurate prediction of flexible pavement performance. The time and temperature dependency of AC materials calls for utilizing advanced material characterization and mechanistic theories, such as viscoelasticity and stress/strain analysis. In layered elastic analysis, as implemented in the new Mechanistic-Empirical Pavement Design Guide (MEPDG), the time dependency is accounted for by calculating the loading times at different AC layer depths. In this study, the time effect on pavement response was evaluated by means of the concept of “pseudo temperature.” With the pavement temperature measured from instrumented thermocouples, the time and temperature dependency of AC materials was integrated into one single factor, termed “effective temperature.” Via this effective temperature, pavement responses under a transient load were predicted through finite element analysis. In the finite element model, viscoelastic behavior of AC materials was characterized through relaxation moduli, while the layers with unbound granular material were assumed to be in an elastic mode. The analysis was conducted for two different AC mixtures in a simplified flexible pavement structure at two different seasons. Finite element analysis results reveal that the loading time has a more pronounced impact on pavement response in the summer for both asphalt types. The results indicate that for reasonable prediction of dynamic response in flexible pavements, the effect of the depth-dependent loading time on pavement temperature should be considered.

  4. Excited-State Dynamics of Carotenoids Studied by Femtosecond Transient Absorption Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ingu; Pang, Yoonsoo [Department of Physics and Photon Science, Gwangju (Korea, Republic of); Lee, Sebok [Gwangju Institute of Science and Technology, Gwangju (Korea, Republic of)

    2014-03-15

    Carotenoids, natural antenna pigments in photosynthesis share a symmetric backbone of conjugated polyenes. Contrary to the symmetric and almost planar geometries of carotenoids, excited state structure and dynamics of carotenoids are exceedingly complex. In this paper, recent infrared and visible transient absorption measurements and excitation dependent dynamics of 8'-apo-β-caroten-8'-al and 7',7'-dicyano-7'-apo-β-carotene will be reviewed. The recent visible transient absorption measurements of 8'-apo-β-caroten-8'-al in polar and nonpolar solvents will also be introduced to emphasize the complex excited-state dynamics and unsolved problems in the S{sub 2} and S{sub 1} excited states.

  5. Transient hydrogen diffusion analyses coupled with crack-tip plasticity under cyclic loading

    International Nuclear Information System (INIS)

    Kotake, Hirokazu; Matsumoto, Ryosuke; Taketomi, Shinya; Miyazaki, Noriyuki

    2008-01-01

    The effect of hydrogen on the material strengths of metals is known as the hydrogen embrittlement, which affects the structural integrity of a hydrogen energy system. In the present paper, we developed a computer program for a transient hydrogen diffusion-elastoplastic coupling analysis by combining an in-house finite element program with a general purpose finite element computer program to analyze hydrogen diffusion. In this program, we use a hypothesis that the hydrogen absorbed in the metal affects the yield stress of the metal. In the present paper, we discuss the effects of the cyclic loading on the hydrogen concentration near the crack tip. An important finding we obtained here is the fact that the hydrogen concentration near the crack tip greatly depends on the loading frequency. This result indicates that the fatigue lives of the components in a hydrogen system depend not only on the number of loading cycles but also on the loading frequency

  6. Influence of resonant magnetic perturbations on transient heat load deposition and fast ion losses

    International Nuclear Information System (INIS)

    Rack, Michael Thomas

    2014-01-01

    Thermonuclear fusion is the energy conversion process which keeps the sun shining. For the last six decades, researchers have been investigating the physics involved in order to enable the usage of this energy supply on Earth. The most promising candidates for fusion power plants are based on magnetic confinement of plasma to provide the ideal conditions for efficient thermonuclear fusion in well controlled surroundings. One important aspect is the control of instabilities that occur in the edge region of the plasma and lead to an ejection of huge amounts of energy. Magnetic perturbation fields which are resonant in the plasma edge are found to modify the plasma favourably and reduce the impact of these instabilities. This dissertation focuses on the effects of resonant magnetic perturbation fields on the ejected energy as well as on the drawbacks of these perturbation fields. The transient energy ejection which is triggered by the instabilities causes extreme heat loads on the wall components in fusion devices. Therefore, it is crucial to understand how resonant magnetic perturbation fields affect the heat load deposition. Furthermore, the impact of resonant magnetic perturbation fields on the confinement of fast ions is an important aspect as fast ions are still required to be well confined in order to avoid additional wall loads and increase the fusion efficiency. Recent upgrades on the Joint European Torus allow for a detailed study of the heat load deposition profiles caused by transient events. Throughout this work, the new features are used for the study of the modifications of the transient heat load depositions that occur if resonant magnetic perturbation fields are applied. This leads to a further understanding of the processes involved during the plasma edge instabilities. Additionally, an alternative method using lower hybrid waves for applying resonant magnetic perturbations is investigated. Furthermore, a new diagnostic, capable of detecting fast ion

  7. Influence of resonant magnetic perturbations on transient heat load deposition and fast ion losses

    Energy Technology Data Exchange (ETDEWEB)

    Rack, Michael Thomas

    2014-07-11

    Thermonuclear fusion is the energy conversion process which keeps the sun shining. For the last six decades, researchers have been investigating the physics involved in order to enable the usage of this energy supply on Earth. The most promising candidates for fusion power plants are based on magnetic confinement of plasma to provide the ideal conditions for efficient thermonuclear fusion in well controlled surroundings. One important aspect is the control of instabilities that occur in the edge region of the plasma and lead to an ejection of huge amounts of energy. Magnetic perturbation fields which are resonant in the plasma edge are found to modify the plasma favourably and reduce the impact of these instabilities. This dissertation focuses on the effects of resonant magnetic perturbation fields on the ejected energy as well as on the drawbacks of these perturbation fields. The transient energy ejection which is triggered by the instabilities causes extreme heat loads on the wall components in fusion devices. Therefore, it is crucial to understand how resonant magnetic perturbation fields affect the heat load deposition. Furthermore, the impact of resonant magnetic perturbation fields on the confinement of fast ions is an important aspect as fast ions are still required to be well confined in order to avoid additional wall loads and increase the fusion efficiency. Recent upgrades on the Joint European Torus allow for a detailed study of the heat load deposition profiles caused by transient events. Throughout this work, the new features are used for the study of the modifications of the transient heat load depositions that occur if resonant magnetic perturbation fields are applied. This leads to a further understanding of the processes involved during the plasma edge instabilities. Additionally, an alternative method using lower hybrid waves for applying resonant magnetic perturbations is investigated. Furthermore, a new diagnostic, capable of detecting fast ion

  8. Dynamic Gust Load Analysis for Rotors

    Directory of Open Access Journals (Sweden)

    Yuting Dai

    2016-01-01

    Full Text Available Dynamic load of helicopter rotors due to gust directly affects the structural stress and flight performance for helicopters. Based on a large deflection beam theory, an aeroelastic model for isolated helicopter rotors in the time domain is constructed. The dynamic response and structural load for a rotor under the impulse gust and slope-shape gust are calculated, respectively. First, a nonlinear Euler beam model with 36 degrees-of-freedoms per element is applied to depict the structural dynamics for an isolated rotor. The generalized dynamic wake model and Leishman-Beddoes dynamic stall model are applied to calculate the nonlinear unsteady aerodynamic forces on rotors. Then, we transformed the differential aeroelastic governing equation to an algebraic one. Hence, the widely used Newton-Raphson iteration algorithm is employed to simulate the dynamic gust load. An isolated helicopter rotor with four blades is studied to validate the structural model and the aeroelastic model. The modal frequencies based on the Euler beam model agree well with published ones by CAMRAD. The flap deflection due to impulse gust with the speed of 2m/s increases twice to the one without gust. In this numerical example, results indicate that the bending moment at the blade root is alleviated due to elastic effect.

  9. Operating experience with high beam currents and transient beam loading in the SLC damping rings

    International Nuclear Information System (INIS)

    Minty, M.G.; Akre, R.; Krejcik, P.; Siemann, R.H.

    1995-01-01

    During the 1994 SLC run the nominal operating intensity in the damping rings was raised from 3.5 x 10 10 to greater than 4 x 10 10 particles per bunch (ppb). Stricter regulation of rf system parameters was required to maintain stability of the rf system and particle beam. Improvements were made in the feedback loops which control the cavity amplitude and loading angles. Compensation for beam loading was also required to prevent klystron saturation during repetition rate changes. To minimize the effects of transient loading on the rf system, the gain of the direct rf feedback loop and the loading angles were optimized

  10. Application of quasi-steady-state plasma streams for simulation of ITER transient heat loads

    International Nuclear Information System (INIS)

    Bandura, A.N.; Chebotarev, V.V.; Garkusha, I.E.; Makhlaj, V.A.; Marchenko, A.K.; Solyakov, D.G.; Tereshin, V.I.; Trubchaninov, S.A.; Tsarenko, A.V.; Landman, I.

    2004-01-01

    The paper presents experimental investigations of energy characteristics of the plasma streams generated with quasi-steady-state plasma accelerator QSPA Kh-50 and adjustment of plasma parameters from the point of view its applicability for simulation of transient plasma heat loads expected for ITER disruptions and type I ELMs. Possibility of generation of high-power magnetized plasma streams with ion impact energy up to 0.6 keV, pulse length of 0.25 ms and heat loads varied in wide range from 0.5 to 30 MJ/m 2 has been demonstrated and some features of plasma interaction with tungsten targets in dependence on plasma heat loads are discussed. (author)

  11. Availability analysis of a turbocharged diesel engine operating under transient load conditions

    International Nuclear Information System (INIS)

    Rakopoulos, C.D.; Giakoumis, E.G.

    2004-01-01

    A computer analysis is developed for studying the energy and availability performance of a turbocharged diesel engine, operating under transient load conditions. The model incorporates many novel features for the simulation of transient operation, such as detailed analysis of mechanical friction, separate consideration for the processes of each cylinder during a cycle ('multi-cylinder' model) and mathematical modeling of the fuel pump. This model has been validated against experimental data taken from a turbocharged diesel engine, located at the authors' laboratory and operated under transient conditions. The availability terms for the diesel engine and its subsystems are analyzed, i.e. cylinder for both the open and closed parts of the cycle, inlet and exhaust manifolds, turbocharger and aftercooler. The present analysis reveals, via multiple diagrams, how the availability properties of the diesel engine and its subsystems develop during the evolution of the engine cycles, assessing the importance of each property. In particular the irreversibilities term, which is absent from any analysis based solely on the first-law of thermodynamics, is given in detail as regards transient response as well as the rate and cumulative terms during a cycle, revealing the magnitude of contribution of all the subsystems to the total availability destruction

  12. Analysis on influence of guide vanes closure laws of pump-turbine on load rejection transient process

    Science.gov (United States)

    Yao, Z.; Bi, H. L.; Huang, Q. S.; Li, Z. J.; Wang, Z. W.

    2013-12-01

    In load rejection transient process, the sudden shut down of guide vanes may cause units speed rise and a sharp increase in water hammer pressure of diversion system, which endangers the safety operation of the power plant. Adopting reasonable guide vane closure law is a kind of economic and effective measurement to reduce the water hammer pressure and limit rotational speed increases. In this paper, combined with Guangzhou Pumped Storage Power Station plant A, the load rejection condition under different guide vanes closure laws is calculated and the key factor of guide vanes closure laws on the impact of the load rejection transition process is analyzed. The different inflection points, which are the closure modes, on the impact of unit speed change, water level fluctuation of surge tank, and the pressure fluctuation of volute inlet and draft tube inlet are further discussed. By compared with the calculation results, a reasonable guide vanes inflection point position can be determined according to security requirements and a reasonable guide vanes closure law can be attained to effectively coordinate the unit speed rise and the rapid pressure change in the load rejection transient process.

  13. Neutronal aspects of PWR control for transient load following

    International Nuclear Information System (INIS)

    Cossic, A.

    1985-01-01

    The purpose of this thesis is to qualify the CRONOS diffusion code on a load transient in grey mode control. First of all, we have established a general axial calculational model and studied the important physical phenomena: xenon oscillation, grey rods absorption, radial leaks modelling, effect of the initial conditions in Iodine and Xenon. In a second stage, a three dimensional calculation has been performed, the results of which have been compared to a PWR 900 TRICASTIN 3 experiment and have been in good agreement. In the last part, we show that the results of the axial model using one-dimensional CRONOS calculations are quite consistent with the three-dimensional calculation [fr

  14. Limitations of transient power loads on DEMO and analysis of mitigation techniques

    Energy Technology Data Exchange (ETDEWEB)

    Maviglia, F., E-mail: francesco.maviglia@euro-fusion.org [EUROfusion Consortium, PPPT Department, Boltzmannstr. 2, Garching (Germany); Consorzio CREATE, University Napoli Federico II – DIETI, 80125 Napoli (Italy); Federici, G. [EUROfusion Consortium, PPPT Department, Boltzmannstr. 2, Garching (Germany); Strohmayer, G. [Max-Planck-Institut fur Plasmaphysik, Boltzmannstr. 2, Garching (Germany); Wenninger, R. [EUROfusion Consortium, PPPT Department, Boltzmannstr. 2, Garching (Germany); Max-Planck-Institut fur Plasmaphysik, Boltzmannstr. 2, Garching (Germany); Bachmann, C. [EUROfusion Consortium, PPPT Department, Boltzmannstr. 2, Garching (Germany); Albanese, R. [Consorzio CREATE, University Napoli Federico II – DIETI, 80125 Napoli (Italy); Ambrosino, R. [Consorzio CREATE University Napoli Parthenope, Naples (Italy); Li, M. [Max-Planck-Institut fur Plasmaphysik, Boltzmannstr. 2, Garching (Germany); Loschiavo, V.P. [Consorzio CREATE, University Napoli Federico II – DIETI, 80125 Napoli (Italy); You, J.H. [Max-Planck-Institut fur Plasmaphysik, Boltzmannstr. 2, Garching (Germany); Zani, L. [CEA, IRFM, F-13108 St Paul-Lez-Durance (France)

    2016-11-01

    Highlights: • A parametric thermo-hydraulic analysis of the candidate DEMO divertor is presented. • The operational space assessment is presented under static and transient heat loads. • Strike points sweeping is analyzed as a divertor power exhaust mitigation technique. • Results are presented on sweeping installed power required, AC losses and thermal fatigue. - Abstract: The present European standard DEMO divertor target technology is based on a water-cooled tungsten mono-block with a copper alloy heat sink. This paper presents the assessment of the operational space of this technology under static and transient heat loads. A transient thermo-hydraulic analysis was performed using the code RACLETTE, which allowed a broad parametric scan of the target geometry and coolant conditions. The limiting factors considered were the coolant critical heat flux (CHF), and the temperature limits of the materials. The second part of the work is devoted to the study of the plasma strike point sweeping as a mitigation technique for the divertor power exhaust. The RACLETTE code was used to evaluate the impact of a large range of sweeping frequencies and amplitudes. A reduced subset of cases, which complied with the constraints, was benchmarked with a 3D FEM model. A reduction of the heat flux to the coolant, up to a factor ∼4, and lower material temperatures were found for an incident heat flux in the range (15–30) MW/m{sup 2}. Finally, preliminary assessments were performed on the installed power required for the sweeping, the AC losses in the superconductors and thermal fatigue analysis. No evident show stoppers were found.

  15. In Situ Test Study of Characteristics of Coal Mining Dynamic Load

    Directory of Open Access Journals (Sweden)

    Jiang He

    2015-01-01

    Full Text Available Combination of coal mining dynamic load and high static stress can easily induce such dynamic disasters as rock burst, coal and gas outburst, roof fall, and water inrush. In order to obtain the characteristic parameters of mining dynamic load and dynamic mechanism of coal and rock, the stress wave theory is applied to derive the relation of mining dynamic load strain rate and stress wave parameters. The in situ test was applied to study the stress wave propagation law of coal mine dynamic load by using the SOS microseismic monitoring system. An evaluation method for mining dynamic load strain rate was proposed, and the statistical evaluation was carried out for the range of strain rate. The research results show that the loading strain rate of mining dynamic load is in direct proportion to the seismic frequency of coal-rock mass and particle peak vibration velocity and is in inverse proportion to wave velocity. The high-frequency component damps faster than the low-frequency component in the shockwave propagating process; and the peak particle vibration velocity has a power functional relationship with the transmitting distance. The loading strain rate of mining dynamic load is generally less than class 10−1/s.

  16. The relevance of the dynamic stall effect for transient fault operations of active-stall wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Jauch, Clemens; Soerensen, Poul; Jensen, Birgitte Bak

    2005-06-15

    This article describes a methodology to quantify the influence of dynamic stall on transient fault operations of active-stall turbines. The model of the dynamic stall effect is introduced briefly. The behaviour of the dynamic stall model during a transient fault operation is described mathematically, and from this its effect quantified. Two quantities are chosen to describe the influence of the dynamic stall effect: one is active power and the other is time delay. Subsequently a transient fault scenario is simulated with and without the dynamic stall effect and the differences discussed. From this comparison, the conclusion is drawn that the dynamic stall effect has some influence on the post-fault behaviour of the wind turbine, and it is hence suggested that the dynamic stall effect is considered if an active-stall wind turbine is to be modelled realistically. (Author)

  17. Equivalent circuit simulation of HPEM-induced transient responses at nonlinear loads

    Directory of Open Access Journals (Sweden)

    M. Kotzev

    2017-09-01

    Full Text Available In this paper the equivalent circuit modeling of a nonlinearly loaded loop antenna and its transient responses to HPEM field excitations are investigated. For the circuit modeling the general strategy to characterize the nonlinearly loaded antenna by a linear and a nonlinear circuit part is pursued. The linear circuit part can be determined by standard methods of antenna theory and numerical field computation. The modeling of the nonlinear circuit part requires realistic circuit models of the nonlinear loads that are given by Schottky diodes. Combining both parts, appropriate circuit models are obtained and analyzed by means of a standard SPICE circuit simulator. It is the main result that in this way full-wave simulation results can be reproduced. Furthermore it is clearly seen that the equivalent circuit modeling offers considerable advantages with respect to computation speed and also leads to improved physical insights regarding the coupling between HPEM field excitation and nonlinearly loaded loop antenna.

  18. Verification and application of MASTER for load follow operation

    International Nuclear Information System (INIS)

    Park, Yong Soo; Cho, Byung Oh; Lee, Chang Ho; Jung, Yil Sup; Park, Chan Oh

    1996-01-01

    The xenon dynamics module in the nuclear design code MASTER was verified through a simulation calculation. The simulation result shows that the xenon dynamics module in MASTER can trace and predict xenon behavior with accuracy under any core transient state and therefore can simulate load follow operations

  19. Transient modeling of an air conditioner with a rapid cycling compressor and multi-indoor units

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wei-Jiang [Institute of Refrigeration and Cryogenics, Shanghai Jiaotong University, Shanghai 200240 (China); Zhang, Chun-Lu [College of Mechanical Engineering, Tongji University, 4800 Cao An Highway, Shanghai 201804 (China)

    2011-01-15

    Rapid cycling the compressor is an alternative of the variable speed compressor to modulate the capacity of refrigeration systems for the purpose of energy saving at part-load conditions. The multi-evaporator air conditioner combined with the rapid cycling compressor brings difficulties in control design because of the sophisticated system physics and dynamics. In this paper the transient model of a multi-split air conditioner with a digital scroll compressor is developed for predicting the system transients under performance modulations. The predicted cycling dynamics are in good agreement with the experimental data. Based on the validated model, the impact of compressor idle power and cycle period to the part load performance is discussed. (author)

  20. Transient modeling of an air conditioner with a rapid cycling compressor and multi-indoor units

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Weijiang [Institute of Refrigeration and Cryogenics, Shanghai Jiaotong University, Shanghai 200240 (China); Zhang Chunlu, E-mail: chunlu.zhang@carrier.utc.co [College of Mechanical Engineering, Tongji University, 4800 Cao An Highway, Shanghai 201804 (China)

    2011-01-15

    Rapid cycling the compressor is an alternative of the variable speed compressor to modulate the capacity of refrigeration systems for the purpose of energy saving at part-load conditions. The multi-evaporator air conditioner combined with the rapid cycling compressor brings difficulties in control design because of the sophisticated system physics and dynamics. In this paper the transient model of a multi-split air conditioner with a digital scroll compressor is developed for predicting the system transients under performance modulations. The predicted cycling dynamics are in good agreement with the experimental data. Based on the validated model, the impact of compressor idle power and cycle period to the part load performance is discussed.

  1. Transient modeling of an air conditioner with a rapid cycling compressor and multi-indoor units

    International Nuclear Information System (INIS)

    Zhang Weijiang; Zhang Chunlu

    2011-01-01

    Rapid cycling the compressor is an alternative of the variable speed compressor to modulate the capacity of refrigeration systems for the purpose of energy saving at part-load conditions. The multi-evaporator air conditioner combined with the rapid cycling compressor brings difficulties in control design because of the sophisticated system physics and dynamics. In this paper the transient model of a multi-split air conditioner with a digital scroll compressor is developed for predicting the system transients under performance modulations. The predicted cycling dynamics are in good agreement with the experimental data. Based on the validated model, the impact of compressor idle power and cycle period to the part load performance is discussed.

  2. Solar wind dynamic pressure variations and transient magnetospheric signatures

    International Nuclear Information System (INIS)

    Sibeck, D.G.; Baumjohann, W.

    1989-01-01

    Contrary to the prevailing popular view, we find some transient ground events with bipolar north-south signatures are related to variations in solar wind dynamic pressure and not necessarily to magnetic merging. We present simultaneous solar wind plasma observations for two previously reported transient ground events observed at dayside auroral latitudes. During the first event, originally reported by Lanzerotti et al. [1987], conjugate ground magnetometers recorded north-south magetic field deflections in the east-west and vertical directions. The second event was reported by Todd et al. [1986], we noted ground rader observations indicating strong northward then southward ionospheric flows. The events were associated with the postulated signatures of patchy, sporadic, merging of magnetosheath and magnetospheric magnetic field lines at the dayside magnetospause, known as flux transfer events. Conversely, we demonstrate that the event reported by Lanzerotti et al. was accompanied by a sharp increase in solar wind dynamic pressure, a magnetospheric compression, and a consequent ringing of the magnetospheric magnetic field. The event reported by Todd et al. was associated with a brief but sharp increase in the solar wind dynamic pressure. copyright American Geophysical Union 1989

  3. Connection and disconnection transients for micro-grids under unbalance load condition

    DEFF Research Database (Denmark)

    Rocabert, J.; Azevedo, Gustavo M.S.; Candela, I.

    2011-01-01

    in connection and disconnection transients. This paper focuses on the design of a method oriented to carry out a stable intentional disconnection, and later re-connection, of local grids from the main distribution grid in an intentional way; also under unbalance load condition. Seamless transfer between grid-connected......The recent grid integration of Distributed Energy Resources (DER) possibility the formation of intentional islands in the case of a grid fault conditions. For such island formation is required an active agent capable of governing the micro-grid connection state in a safe mode, especially...

  4. Erosion of tungsten armor after multiple intense transient events in ITER

    International Nuclear Information System (INIS)

    Bazylev, B.N.; Janeschitz, G.; Landman, I.S.; Pestchanyi, S.E.

    2005-01-01

    Macroscopic erosion by melt motion is the dominating damage mechanism for tungsten armour under high-heat loads with energy deposition W > 1 MJ/m 2 and τ > 0.1 ms. For ITER divertor armour the results of a fluid dynamics simulation of the melt motion erosion after repetitive stochastically varying plasma heat loads of consecutive disruptions interspaced by ELMs are presented. The heat loads for particular single transient events are numerically simulated using the two-dimensional MHD code FOREV-2D. The whole melt motion is calculated by the fluid dynamics code MEMOS-1.5D. In addition for the ITER dome melt motion erosion of tungsten armour caused by the lateral radiation impact from the plasma shield at the disruption and ELM heat loads is estimated

  5. Erosion of tungsten armor after multiple intense transient events in ITER

    Science.gov (United States)

    Bazylev, B. N.; Janeschitz, G.; Landman, I. S.; Pestchanyi, S. E.

    2005-03-01

    Macroscopic erosion by melt motion is the dominating damage mechanism for tungsten armour under high-heat loads with energy deposition W > 1 MJ/m 2 and τ > 0.1 ms. For ITER divertor armour the results of a fluid dynamics simulation of the melt motion erosion after repetitive stochastically varying plasma heat loads of consecutive disruptions interspaced by ELMs are presented. The heat loads for particular single transient events are numerically simulated using the two-dimensional MHD code FOREV-2D. The whole melt motion is calculated by the fluid dynamics code MEMOS-1.5D. In addition for the ITER dome melt motion erosion of tungsten armour caused by the lateral radiation impact from the plasma shield at the disruption and ELM heat loads is estimated.

  6. Structure and dynamics of paramagnetic transients by pulsed EPR and NMR detection of nuclear resonance

    International Nuclear Information System (INIS)

    Trifunac, A.D.

    1981-01-01

    Structure and dynamics of transient radicals in pulse radiolysis can be studied by time resolved EPR and NMR techniques. EPR study of kinetics and relaxation is illustrated. The NMR detection of nuclear resonance in transient radicals is a new method which allows the study of hyperfine coupling, population dynamics, radical kinetics, and reaction mechanism. 9 figures

  7. The dynamic behavior of the SUPER-PHENIX reactor under unprotected transient

    International Nuclear Information System (INIS)

    Gouriou, A.; Francillon, E.; Kayser, G.; Malenfer, G.; Languille, A.

    1982-01-01

    Due to design changes and progress on the knowledge of feed-back effects, a reactualization of the dynamic behavior of SUPER-PHENIX under unprotected transients was undertaken. We present the main data on feed-back characteristics and the results of dynamic calculations. With the present state of knowledge, the former conclusion is confirmed: the dynamic evolution is very slow and no irreversible phenomena happen in the short term

  8. Considering transient population dynamics in the conservation of slow life-history species: An application to the sandhill crane

    Science.gov (United States)

    Gerber, Brian D.; Kendall, William L.

    2016-01-01

    The importance of transient dynamics of structured populations is increasingly recognized in ecology, yet these implications are not largely considered in conservation practices. We investigate transient and long-term population dynamics to demonstrate the process and utility of incorporating transient dynamics into conservation research and to better understand the population management of slow life-history species; these species can be theoretically highly sensitive to short- and long-term transient effects. We are specifically interested in the effects of anthropogenic removal of individuals from populations, such as caused by harvest, poaching, translocation, or incidental take. We use the sandhill crane (Grus canadensis) as an exemplar species; it is long-lived, has low reproduction, late maturity, and multiple populations are subject to sport harvest. We found sandhill cranes to have extremely high potential, but low likelihood for transient dynamics, even when the population is being harvested. The typically low population growth rate of slow life-history species appears to buffer against many perturbations causing large transient effects. Transient dynamics will dominate population trajectories of these species when stage structures are highly biased towards the younger and non-reproducing individuals, a situation that may be rare in established populations of long-lived animals. However, short-term transient population growth can be highly sensitive to vital rates that are relatively insensitive under equilibrium, suggesting that stage structure should be known if perturbation analysis is used to identify effective conservation strategies. For populations of slow life-history species that are not prone to large perturbations to their most productive individuals, population growth may be approximated by equilibrium dynamics.

  9. A modeling approach for district heating systems with focus on transient heat transfer in pipe networks

    DEFF Research Database (Denmark)

    Mohammadi, Soma; Bojesen, Carsten

    2015-01-01

    the temperature in DH systems. The main focus is on modeling transient heat transfer in pipe networks regarding the time delays between the heat supply unit and the consumers, the heat loss in the pipe networks and the consumers’ dynamic heat loads. A pseudo-dynamic approach is adopted and also the implicit...... district heating networks [DHN] characteristics. This paper is presenting a new developed model, which reflects the thermo-dynamic behavior of DHN. It is designed for tree network topologies. The purpose of the model is to serve as a basis for applying a variety of scenarios towards lowering...... finite element method is applied to simulate transient temperature changes in pipe networks. The model is calculating time series data related to supply temperature to the DHN from heat production units, heat loads and return temperature related to each consumer to calculate dynamic temperature changes...

  10. Scaling Laws in the Transient Dynamics of Firefly-like Oscillators

    International Nuclear Information System (INIS)

    Rubido, N; Cabeza, C; Marti, A; Ramirez Avila, G M

    2011-01-01

    Fireflies constitute a paradigm of pulse-coupled oscillators. In order to tackle the problems related to synchronisation transients of pulse-coupled oscillators, a Light-Controlled Oscillator (LCO) model is presented. A single LCO constitutes a one-dimensional relaxation oscillator described by two distinct time-scales meant to mimic fireflies in the sense that: it is capable of emitting light in a pulse-like fashion and detect the emitted by others in order to adjust its oscillation. We present dynamical results for two interacting LCOs in the torus for all possible coupling configurations. Transient times to the synchronous limit cycle are obtained experimentally and numerically as a function of initial conditions and coupling strengths. Scaling laws are found based on dimensional analysis and critical exponents calculated, thus, global dynamic is restricted. Furthermore, an analytical orthogonal transformation that allows to calculate Floquet multipliers directly from the time series is presented. As a consequence, local dynamics is also fully characterized. This transformation can be easily extended to a system with an arbitrary number of interacting LCOs.

  11. The spatially asymmetric cost of memory load on visual perception: transient stimulus-centered neglect.

    Science.gov (United States)

    Gozli, Davood G; Wilson, Kristin E; Ferber, Susanne

    2014-04-01

    Recent evidence suggests that visual working memory (VWM) load reduces performance accuracy on a concurrent visual recognition task, particularly for objects presented in the left hemifield. It has also been shown that high VWM load causes suppression of activity in the right temporoparietal junction (TPJ). Given the resemblance of VWM load effects to symptoms of unilateral neglect (i.e., impaired perception on the left side and lesion to the right TPJ), we investigated whether VWM load effects are restricted to the left side of space or extend to object-centered reference frames. In other words, akin to object-centered neglect, can high VWM load cause a perceptual cost in attending to the left side of the stimulus? We addressed this question using an object recognition task (Experiment 1) and a visual search task (Experiment 2) showing that this transient left-neglect can indeed be modulated by an object-centered frame of reference. These findings suggest that load-induced impairments of visual attention are spatially asymmetric and can emerge within multiple spatial reference frames. Therefore, the attentional consequences of high VWM load on conscious perception may serve as a useful model of unilateral perceptual neglect.

  12. Reduction of Dynamic Loads in Mine Lifting Installations

    Science.gov (United States)

    Kuznetsov, N. K.; Eliseev, S. V.; Perelygina, A. Yu

    2018-01-01

    Article is devoted to a problem of decrease in the dynamic loadings arising in transitional operating modes of the mine lifting installations leading to heavy oscillating motions of lifting vessels and decrease in efficiency and reliability of work. The known methods and means of decrease in dynamic loadings and oscillating motions of the similar equipment are analysed. It is shown that an approach based on the concept of the inverse problems of dynamics can be effective method of the solution of this problem. The article describes the design model of a one-ended lifting installation in the form of a two-mass oscillation system, in which the inertial elements are the mass of the lifting vessel and the reduced mass of the engine, reducer, drum and pulley. The simplified mathematical model of this system and results of an efficiency research of an active way of reduction of dynamic loadings of lifting installation on the basis of the concept of the inverse problems of dynamics are given.

  13. Probing carrier dynamics of individual layers in a heterostructure using transient reflectivity

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Salahuddin; Jayabalan, J., E-mail: jjaya@rrcat.gov.in; Singh, Asha; Yogi, Rachana; Chari, Rama [Laser Physics Applications Section, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India)

    2015-09-21

    We report the wavelength dependent transient reflectivity measurements in AlGaAs-GaAs heterostructures having two-dimensional electron (or hole) gas near the interface. Using a multilayer model for transient reflectivity, we show that the magnitude and sign of contributions from the carriers in two-dimensional electron (or hole) gas and GaAs to the total signal depends on the wavelength. Further, it has been shown that it is possible to study the carrier dynamics in a given layer of a heterostructure by performing transient reflectivity at specific wavelengths.

  14. Probing carrier dynamics of individual layers in a heterostructure using transient reflectivity

    International Nuclear Information System (INIS)

    Khan, Salahuddin; Jayabalan, J.; Singh, Asha; Yogi, Rachana; Chari, Rama

    2015-01-01

    We report the wavelength dependent transient reflectivity measurements in AlGaAs-GaAs heterostructures having two-dimensional electron (or hole) gas near the interface. Using a multilayer model for transient reflectivity, we show that the magnitude and sign of contributions from the carriers in two-dimensional electron (or hole) gas and GaAs to the total signal depends on the wavelength. Further, it has been shown that it is possible to study the carrier dynamics in a given layer of a heterostructure by performing transient reflectivity at specific wavelengths

  15. Dynamic load mitigation using dissipative elastic metamaterials with multiple Maxwell-type oscillators

    Science.gov (United States)

    Alamri, Sagr; Li, Bing; Tan, K. T.

    2018-03-01

    Dissipative elastic metamaterials have attracted increased attention in recent times. This paper presents the development of a dissipative elastic metamaterial with multiple Maxwell-type resonators for stress wave attenuation. The mechanism of the dissipation effect on the vibration characteristics is systematically investigated by mass-spring-damper models with single and dual resonators. Based on the parameter optimization, it is revealed that a broadband wave attenuation region (stopping band) can be obtained by properly utilizing interactions from resonant motions and viscoelastic effects of the Maxwell-type oscillators. The relevant numerical verifications are conducted for various cases, and excellent agreement between the numerical and theoretical frequency response functions is shown. The design of this dissipative metamaterial system is further applied for dynamic load mitigation and blast wave attenuation. Moreover, the transient response in the continuum model is designed and analyzed for more robust design. By virtue of the bandgap merging effect induced by the Maxwell-type damper, the transient blast wave can be almost completely suppressed in the low frequency range. A significantly improved performance of the proposed dissipative metamaterials for stress wave mitigation is verified in both time and frequency domains.

  16. Complex dynamics and switching transients in periodically forced Filippov prey–predator system

    International Nuclear Information System (INIS)

    Tang, Guangyao; Qin, Wenjie; Tang, Sanyi

    2014-01-01

    Highlights: •We develop a Filippov prey–predator model with periodic forcing. •The sliding mode dynamics and its domain have been investigated. •The existence and stability of sliding periodic solution have been discussed. •The complex dynamics are addressed through bifurcation analyses. •Switching transients and their biological implications have been discussed. - Abstract: By employing threshold policy control (TPC) in combination with the definition of integrated pest management (IPM), a Filippov prey–predator model with periodic forcing has been proposed and studied, and the periodic forcing is affected by assuming a periodic variation in the intrinsic growth rate of the prey. This study aims to address how the periodic forcing and TPC affect the pest control. To do this, the sliding mode dynamics and sliding mode domain have been addressed firstly by using Utkin’s equivalent control method, and then the existence and stability of sliding periodic solution are investigated. Furthermore, the complex dynamics including multiple attractors coexistence, period adding sequences and chaotic solutions with respect to bifurcation parameters of forcing amplitude and economic threshold (ET) have been investigated numerically in more detail. Finally the switching transients associated with pest outbreaks and their biological implications have been discussed. Our results indicate that the sliding periodic solution could be globally stable, and consequently the prey or pest population can be controlled such that its density falls below the economic injury level (EIL). Moreover, the switching transients have both advantages and disadvantages concerning pest control, and the magnitude and frequency of switching transients depend on the initial values of both populations, forcing amplitude and ET

  17. Shaking of reinforced concrete structures subjected to transient dynamic analysis

    International Nuclear Information System (INIS)

    Rouzaud, Christophe

    2015-01-01

    In the design of nuclear engineering structures security and safety present a crucial aspect. Civil engineering design and the qualification of materials to dynamic loads must consider the accelerations which they undergo. These accelerations could integrate seismic activity and shaking movements consecutive to aircraft impact with higher cut-off frequency. Current methodologies for assessing this shock are based on transient analyses using classical finite element method associated with explicit numerical schemes or projection on modal basis, often linear. In both cases, to represent in meaningful way a medium-frequency content, it should implement a mesh refinement which is hardly compatible with the size of models of the civil engineering structures. In order to extend industrial methodologies used and to allow a better representation of the behavior of the structure in medium-frequency, an approach coupling a temporal and non-linear analysis for shock area with a frequency approach to treatment of shaking with VTCR (Variational Theory of Complex Rays) has been used. The aim is to use the computational efficiency of the implemented strategy, including medium frequency to describe the nuclear structures to aircraft impact. (author)

  18. A transient-enhanced NMOS low dropout voltage regulator with parallel feedback compensation

    International Nuclear Information System (INIS)

    Wang Han; Tan Lin

    2016-01-01

    This paper presents a transient-enhanced NMOS low-dropout regulator (LDO) for portable applications with parallel feedback compensation. The parallel feedback structure adds a dynamic zero to get an adequate phase margin with a load current variation from 0 to 1 A. A class-AB error amplifier and a fast charging/discharging unit are adopted to enhance the transient performance. The proposed LDO has been implemented in a 0.35 μm BCD process. From experimental results, the regulator can operate with a minimum dropout voltage of 150 mV at a maximum 1 A load and I Q of 165 μA. Under the full range load current step, the voltage undershoot and overshoot of the proposed LDO are reduced to 38 mV and 27 mV respectively. (paper)

  19. Geometrically Nonlinear Transient Response of Laminated Plates with Nonlinear Elastic Restraints

    Directory of Open Access Journals (Sweden)

    Shaochong Yang

    2017-01-01

    Full Text Available To investigate the dynamic behavior of laminated plates with nonlinear elastic restraints, a varied constraint force model and a systematic numerical procedure are presented in this work. Several kinds of typical relationships of force-displacement for spring are established to simulate the nonlinear elastic restraints. In addition, considering the restraining moments of flexible pads, the pads are modeled by translational and rotational springs. The displacement- dependent constraint forces are added to the right-hand side of equations of motion and treated as additional applied loads. These loads can be explicitly defined, via an independent set of nonlinear load functions. The time histories of transverse displacements at typical points of the laminated plate are obtained through the transient analysis. Numerical examples show that the present method can effectively treat the geometrically nonlinear transient response of plates with nonlinear elastic restraints.

  20. Analysis of low load transients for the Vandellos-II NPP

    International Nuclear Information System (INIS)

    Llopis, C.; Reventos, F.; Batet, L.; Pretel, C.; Sol, I.

    2007-01-01

    The Technical University of Catalonia (UPC) has been jointly working with the Asociacion Nuclear Asco-Vandellos (ANAV) for a number of years in order to establish, qualify and use best estimate (BE) models for the reactors under the control of ANAV. ANAV is the consortium that is responsible for operation of the Asco and Vandellos-II reactors. The reactors are Westinghouse-design three-loop PWRs with an approximate electrical power of 1000 MW. The existing integral plant models for each plant are currently used for many different purposes among which are support of plant operation and control. Quite a number of studies have been done in order to improve both safety and plant competitiveness. Most of these dynamic analyses were carried out in relation to transients starting at nominal full power or at least, very close to full power. This paper develops a specific use of the Vandellos-II plant model for operation and control support at low power involving new ranges of system actuation parameters. It also examines scenarios that are somewhat different from those typically analysed. The study starts showing the results of an assessment case, which is a start-up test and provides some additional qualification, and subsequently attempts to establish calculations to support both an improvement in feed water controls and to set up operating recommendations for low-load manual operation of feed water turbo-pump. Both results hopefully, will produce an outcome, which leads to an improvement in safety and reduces reactor trip probability

  1. Transient Dynamics Analysis of The Reachstacker Speader Based On ANSYS

    Directory of Open Access Journals (Sweden)

    Shu Yu Feng

    2016-01-01

    Full Text Available Reachstacker is an indispensable handling machinery, it will inevitably lead to unbalanced force at the job site. This paper does transient dynamics analysis for the spreader mechanism, which is one of the most significance key components. We get dynamic response of the spreader in lifting instant, results not only provide a reference for designers to understand the mechanical characteristics of spreader comprehensively, but also bedding for the future research.

  2. Spent nuclear fuel system dynamic stability under normal conditions of transportation

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Hao; Wang, Jy-An John, E-mail: wangja@ornl.gov

    2016-12-15

    Highlights: • A conformational potential effect of fuel assembly contact interaction induced transient shock. • Complex vibration modes and vibration load intensity were observed from fuel assembly system. • The project was able to link the periodic transient shock to spent fuel fatigue strength reduction. - Abstract: In a horizontal layout of a spent nuclear fuel (SNF) assembly under normal conditions of transportation (NCT), the fuel assembly’s skeleton formed by guide tubes and spacer grids is the primary load bearing structure for carrying and transferring the vibration loads within an SNF assembly. Therefore, the integrity of guide tubes and spacer grids will dictate the vibration amplitude/intensity of the fuel assembly during transport, and must be considered when designing multipurpose purpose canister (MPC) for safe SNF transport. This paper investigates the SNF assembly deformation dynamics during normal vibration mode, as well as the transient shock mode inside the cask during NCT. Dynamic analyses were performed in the frequency domain to study frequency characteristic of the fuel assembly system and in the time domain to simulate the transient dynamic response of the fuel assembly. To further evaluate the intensity of contact interaction induced by the local contacts’ impact loading at the spacer grid, detailed models of the actual spring and dimples of the spacer grids were created. The impacts between the fuel rod and springs and dimples were simulated with a 20 g transient shock load. The associated contact interaction intensities, in terms of reaction forces, were estimated from the finite element analyses (FEA) results. The bending moment estimated from the resultant stress on the clad under 20 g transient shock can be used to define the loading in cyclic integrated reversible-bending fatigue tester (CIRFT) vibration testing for the equivalent condition. To estimate the damage potential of the transient shock to the SNF vibration

  3. Transient dynamics of the flow around a NACA 0015 airfoil using fluidic vortex generators

    Energy Technology Data Exchange (ETDEWEB)

    Siauw, W.L. [Institut Pprime, CNRS - Universite de Poitiers - ENSMA, UPR 3346, Departement Fluides, Thermique, Combustion, ENSMA - Teleport 2, 1 Avenue Clement Ader, BP 40109, F-86961 Futuroscope Chasseneuil Cedex (France); Bonnet, J.-P., E-mail: Jean-Paul.Bonnet@univ-poitiers.f [Institut Pprime, CNRS - Universite de Poitiers - ENSMA, UPR 3346, Departement Fluides, Thermique, Combustion, CEAT, 43 rue de l' Aerodrome, F-86036 Poitiers Cedex (France); Tensi, J., E-mail: Jean.Tensi@lea.univ-poitiers.f [Institut Pprime, CNRS - Universite de Poitiers - ENSMA, UPR 3346, Departement Fluides, Thermique, Combustion, ENSMA - Teleport 2, 1 Avenue Clement Ader, BP 40109, F-86961 Futuroscope Chasseneuil Cedex (France); Cordier, L., E-mail: Laurent.Cordier@univ-poitiers.f [Institut Pprime, CNRS - Universite de Poitiers - ENSMA, UPR 3346, Departement Fluides, Thermique, Combustion, CEAT, 43 rue de l' Aerodrome, F-86036 Poitiers Cedex (France); Noack, B.R., E-mail: Bernd.Noack@univ-poitiers.f [Institut Pprime, CNRS - Universite de Poitiers - ENSMA, UPR 3346, Departement Fluides, Thermique, Combustion, CEAT, 43 rue de l' Aerodrome, F-86036 Poitiers Cedex (France); Cattafesta, L., E-mail: cattafes@ufl.ed [Florida Center for Advanced Aero-Propulsion (FCAAP), Department of Mechanical and Aerospace Engineering, University of Florida, 231 MAE-A, Gainesville, FL 32611 (United States)

    2010-06-15

    The unsteady activation or deactivation of fluidic vortex generators on a NACA 0015 airfoil is studied to understand the transient dynamics of flow separation control. The Reynolds number is high enough and the boundary layer is tripped, so the boundary layer is fully turbulent prior to separation. Conditional PIV of the airfoil wake is obtained phase-locked to the actuator trigger signal, allowing reconstruction of the transient processes. When the actuators are impulsively turned on, the velocity field in the near wake exhibit a complex transient behavior associated with the formation and shedding of a starting vortex. When actuation is stopped, a more gradual process of the separation dynamics is found. These results are in agreement with those found in the literature in comparable configurations. Proper Orthogonal Decomposition of phase-locked velocity fields reveals low-dimensional transient dynamics for the attachment and separation processes, with 98% of the fluctuation energy captured by the first four modes. The behavior is quantitatively well captured by a four-dimensional dynamical system with the corresponding mode amplitudes. Analysis of the first temporal POD modes accurately determines typical time scales for attachment and separation processes to be respectively t{sup +}=10 and 20 in conventional non-dimensional values. This study adds to experimental investigations of this scale with essential insight for the targeted closed-loop control.

  4. Dynamic Load Balancing of Parallel Monte Carlo Transport Calculations

    International Nuclear Information System (INIS)

    O'Brien, M; Taylor, J; Procassini, R

    2004-01-01

    The performance of parallel Monte Carlo transport calculations which use both spatial and particle parallelism is increased by dynamically assigning processors to the most worked domains. Since the particle work load varies over the course of the simulation, this algorithm determines each cycle if dynamic load balancing would speed up the calculation. If load balancing is required, a small number of particle communications are initiated in order to achieve load balance. This method has decreased the parallel run time by more than a factor of three for certain criticality calculations

  5. LOFT facility PSS experiments: analysis of wet well vertical loads resulting from transient initiation

    International Nuclear Information System (INIS)

    Berta, V.T.

    1977-05-01

    Fourteen experiments on the Loss-of-Fluid Test (LOFT) facility pressure suppression system (PSS) are analyzed in relation to the vertical load generated on the suppression tank in the first 0.5 sec of the transient. Variations in principle parameters affecting the generation of vertical loads were included in the experiments. The internal and external vent submergences are identified from the analysis as being parameters which are first order in influencing the magnitude of the vertical load. These parameters are geometric in nature and depend only on PSS design. Physical parameters of total energy input and rate of energy input to the dry well, which influence the dry well pressurization, also are identified as being first order in influencing the magnitude of the vertical loads. The vertical load magnitude is a direct function of these geometric and physical parameters. The analysis indicates that a small value in any one of the parameters will cause the vertical load to be small and to have little dependence on the magnitude of the other parameters. In addition, the phenomena of nonuniform nonsynchronized vent inlet pressures, which have origins that are either geometric, physical, or a combination of both, act as a significant vertical load reduction mechanism

  6. Purinergic responses of chondrogenic stem cells to dynamic loading

    Directory of Open Access Journals (Sweden)

    Gađanski Ivana

    2013-01-01

    Full Text Available In habitually loaded tissues, dynamic loading can trigger ATP (adenosine 5’- triphosphate release to extracellular environment, and result in calcium signaling via ATP binding to purine P2 receptors1. In the current study we have compared purinergic responses (ATP release of two types of cells: bovine chondrocytes (bCHs and human mesenchymal stem cells (hMSC that were encapsulated in agarose and subjected to dynamic loading. Both cell types were cultured under chondrogenic conditions, and their responses to loading were evaluated by ATP release assay in combination with connexin (Cx-sensitive fluorescent dye (Lucifer Yellow - LY and a Cx-hemichannel blocker (Flufenamic acid - FFA. In response to dynamic loading, chondrogenic hMSCs released significantly higher amounts of ATP (5-fold in comparison to the bCHs early in culture (day 2. Triggering of LY uptake in the bCHs and hMSCs by dynamic loading implies opening of the Cx-hemichannels. However, the number of LY-positive cells in hMSC-constructs was 2.5-fold lower compared to the loaded bCH-constructs, suggesting utilization of additional mechanisms of ATP release. Cx-reactive sites were detected in both bCHs and hMSCs-constructs. FFA application led to reduced ATP release both in bCHs and hMSCs, which confirms the involvement of connexin hemichannels, with more prominent effects in bCHs than in hMSCs, further implying the existence of additional mechanism of ATP release in chondrogenic hMSCs. Taken together, these results indicate stronger purinergic response to dynamic loading of chondrogenic hMSCs than primary chondrocytes, by activation of connexin hemichannels and additional mechanisms of ATP release. [Projekat Ministrastva nauke Republike Srbije, ON174028 i br. III41007

  7. Dynamic strength of rock with single planar joint under various loading rates at various angles of loads applied

    Directory of Open Access Journals (Sweden)

    Pei-Yun Shu

    2018-06-01

    Full Text Available Intact rock-like specimens and specimens that include a single, smooth planar joint at various angles are prepared for split Hopkinson pressure bar (SHPB testing. A buffer pad between the striker bar and the incident bar of an SHPB apparatus is used to absorb some of the shock energy. This can generate loading rates of 20.2–4627.3 GPa/s, enabling dynamic peak stresses/strengths and associated failure patterns of the specimens to be investigated. The effects of the loading rate and angle of load applied on the dynamic peak stresses/strengths of the specimens are examined. Relevant experimental results demonstrate that the failure pattern of each specimen can be classified as four types: Type A, integrated with or without tiny flake-off; Type B, slide failure; Type C, fracture failure; and Type D, crushing failure. The dynamic peak stresses/strengths of the specimens that have similar failure patterns increase linearly with the loading rate, yielding high correlations that are evident on semi-logarithmic plots. The slope of the failure envelope is the smallest for slide failure, followed by crushing failure, and that of fracture failure is the largest. The magnitude of the plot slope of the dynamic peak stress against the loading rate for the specimens that are still integrated after testing is between that of slide failure and crushing failure. The angle of application has a limited effect on the dynamic peak stresses/strengths of the specimens regardless of the failure pattern, but it affects the bounds of the loading rates that yield each failure pattern, and thus influences the dynamic responses of the single jointed specimen. Slide failure occurs at the lowest loading rate of any failure, but can only occur in single jointed specimen that allows sliding. Crushing failure is typically associated with the largest loading rate, and fracture failure may occur when the loading rate is between the boundaries for slide failure and crushing

  8. General purpose dynamic Monte Carlo with continuous energy for transient analysis

    Energy Technology Data Exchange (ETDEWEB)

    Sjenitzer, B. L.; Hoogenboom, J. E. [Delft Univ. of Technology, Dept. of Radiation, Radionuclide and Reactors, Mekelweg 15, 2629JB Delft (Netherlands)

    2012-07-01

    For safety assessments transient analysis is an important tool. It can predict maximum temperatures during regular reactor operation or during an accident scenario. Despite the fact that this kind of analysis is very important, the state of the art still uses rather crude methods, like diffusion theory and point-kinetics. For reference calculations it is preferable to use the Monte Carlo method. In this paper the dynamic Monte Carlo method is implemented in the general purpose Monte Carlo code Tripoli4. Also, the method is extended for use with continuous energy. The first results of Dynamic Tripoli demonstrate that this kind of calculation is indeed accurate and the results are achieved in a reasonable amount of time. With the method implemented in Tripoli it is now possible to do an exact transient calculation in arbitrary geometry. (authors)

  9. Effect of transient occlusal loading on the threshold of tooth tactile sensation perception for tapping like the impulsive stimulation.

    Science.gov (United States)

    Morimoto, Yuta; Oki, Kazuhiro; Iida, Sachiyo; Shirahige, Chieko; Maeda, Naoto; Kawakami, Shigehisa; Matsunaga, Tadashi; Minagi, Shogo

    2013-07-01

    The objectives of this study were (1) to establish a reliable method for detecting the force threshold of the tooth tactile sensation while avoiding experimenter bias and (2) to examine the effect of occlusal force loading on the threshold for impulsive force stimulation in subjects with normal dentition. Twenty volunteers participated in this study (10 males and 10 females; mean age, 26.6 ± 2.9 years). To simulate the bite force during occlusal tapping, a force-loading device was designed to exert impulsive force to the occlusal surface in the direction parallel to the tooth axis. The impulsive force detection threshold of the periodontal sensation was measured before and after loading 98 N of occlusal force on the left upper first molar for 1 min. Transient mechanical loading of the upper first molar caused an increase in the absolute threshold for impulsive force. This increase did not vanish immediately, and the increment of the threshold was maintained during the remainder of the experiment. A computer-controlled method for the evaluation of tooth tactile sensation using impulsive stimulation was established. Transient occlusal force loading parallel to the tooth axis increases the threshold of periodontal sensation for mechanical impulsive stimulation.

  10. Transient analysis of a U-tube natural circulation steam generator

    Energy Technology Data Exchange (ETDEWEB)

    Gaikwad, A J; Kumar, Rajesh; Bhadra, Anu; Chakraborty, G; Venkat Raj, V [Reactor Safety Division, Bhabha Atomic Research Centre, Mumbai (India)

    1994-06-01

    A computer code has been developed, for transient thermal-hydraulic analysis of proposed 500 MWe PHWR steam generator. The transient behaviour of a nuclear power plant is very much dependent on the steam generator performance, as it provides a thermal linkage between the primary and secondary systems. Study of dynamics of steam generator is essential for over all power plant dynamics as well as design of control systems for steam generator. A mathematical model has been developed for the simulation of thermal-hydraulic phenomena in a U tube natural circulation steam generator. Fluid model is based on one dimensional, nonlinear, single fluid conservation equations of mass, momentum, energy and equation of state. This model includes coupled two phase flow heat transfer and natural circulation. The model accounts for both compressibility and thermal expansion effects. The process simulation and results obtained for transients such as step change in load and total loss of feed water are presented. (author). 5 refs., 7 figs.

  11. Combined impact of transient heat loads and steady-state plasma exposure on tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Huber, Alexander, E-mail: A.Huber@fz-juelich.de [Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung, 52425 Jülich (Germany); Wirtz, Marius; Sergienko, Gennady; Steudel, Isabel [Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung, 52425 Jülich (Germany); Arakcheev, Aleksey; Burdakov, Aleksander [Budker Institute of Nuclear Physics (BINP), Novosibirsk 630090 (Russian Federation); Esser, Hans Guenter; Freisinger, Michaele; Kreter, Arkadi; Linke, Jochen; Linsmeier, Christian; Mertens, Philippe; Möller, Sören; Philipps, Volker; Pintsuk, Gerald; Reinhart, Michael; Schweer, Bernd [Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung, 52425 Jülich (Germany); Shoshin, Andrey [Budker Institute of Nuclear Physics (BINP), Novosibirsk 630090 (Russian Federation); Terra, Alexis; Unterberg, Bernhard [Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung, 52425 Jülich (Germany)

    2015-10-15

    Highlights: • W-samples under combined loading conditions show a lower damage threshold. • The pre-loaded W-samples show a lower damage threshold due to the D- embrittlement. • Pronounced increase of the D retention has been observed during the combined loads. • Enhanced blister formation has been observed under combined loading conditions. - Abstract: Cracking thresholds and crack patterns in tungsten targets have been studied in recent experiments after repetitive ITER-like ELM heat pulses in combination with plasma exposure in PSI-2 (Γ{sub target} = 2.5–4.0 × 10{sup 21} m{sup −2} s{sup −1}, ion energy on surface E{sub ion} = 60 eV, T{sub e} ≈ 10 eV). The heat pulses were simulated by laser irradiation. A Nd:YAG laser with energy per pulse of up to 32 J and a duration of 1 ms at the fundamental wavelength (λ = 1064 nm, repetition rate 0.5 Hz) was used to irradiate ITER-grade W samples with repetitive heat loads. In contrast to pure thermal exposure with a laser beam where the damage threshold under pure heat loads for ITER-grade W lies between 0.38 and 0.76 GW/m{sup 2}, the experiments with pre-loaded W-samples as well as under combined loading conditions show a lower damage threshold of 0.3 GW/m{sup 2}. This is probably due to deuterium embrittlement and/or a higher defect concentration in a region close to the surface due to supersaturation with deuterium. A pronounced increase in the D retention (more than a factor of five) has been observed during the combined transient heat loads and plasma exposure. Enhanced blister formation has been observed under these combined loading conditions.

  12. Combined impact of transient heat loads and steady-state plasma exposure on tungsten

    International Nuclear Information System (INIS)

    Huber, Alexander; Wirtz, Marius; Sergienko, Gennady; Steudel, Isabel; Arakcheev, Aleksey; Burdakov, Aleksander; Esser, Hans Guenter; Freisinger, Michaele; Kreter, Arkadi; Linke, Jochen; Linsmeier, Christian; Mertens, Philippe; Möller, Sören; Philipps, Volker; Pintsuk, Gerald; Reinhart, Michael; Schweer, Bernd; Shoshin, Andrey; Terra, Alexis; Unterberg, Bernhard

    2015-01-01

    Highlights: • W-samples under combined loading conditions show a lower damage threshold. • The pre-loaded W-samples show a lower damage threshold due to the D- embrittlement. • Pronounced increase of the D retention has been observed during the combined loads. • Enhanced blister formation has been observed under combined loading conditions. - Abstract: Cracking thresholds and crack patterns in tungsten targets have been studied in recent experiments after repetitive ITER-like ELM heat pulses in combination with plasma exposure in PSI-2 (Γ_t_a_r_g_e_t = 2.5–4.0 × 10"2"1 m"−"2 s"−"1, ion energy on surface E_i_o_n = 60 eV, T_e ≈ 10 eV). The heat pulses were simulated by laser irradiation. A Nd:YAG laser with energy per pulse of up to 32 J and a duration of 1 ms at the fundamental wavelength (λ = 1064 nm, repetition rate 0.5 Hz) was used to irradiate ITER-grade W samples with repetitive heat loads. In contrast to pure thermal exposure with a laser beam where the damage threshold under pure heat loads for ITER-grade W lies between 0.38 and 0.76 GW/m"2, the experiments with pre-loaded W-samples as well as under combined loading conditions show a lower damage threshold of 0.3 GW/m"2. This is probably due to deuterium embrittlement and/or a higher defect concentration in a region close to the surface due to supersaturation with deuterium. A pronounced increase in the D retention (more than a factor of five) has been observed during the combined transient heat loads and plasma exposure. Enhanced blister formation has been observed under these combined loading conditions.

  13. Transient Performance of a Vertical Axis Wind Turbine

    Science.gov (United States)

    Onol, Aykut; Yesilyurt, Serhat

    2016-11-01

    A coupled CFD/rotor dynamics modeling approach is presented for the analysis of realistic transient behavior of a height-normalized, three-straight-bladed VAWT subject to inertial effects of the rotor and generator load which is manipulated by a feedback control under standardized wind gusts. The model employs the k- ɛ turbulence model to approximate unsteady Reynolds-averaged Navier-Stokes equations and is validated with data from field measurements. As distinct from related studies, here, the angular velocity is calculated from the rotor's equation of motion; thus, the dynamic response of the rotor is taken into account. Results include the following: First, the rotor's inertia filters large amplitude oscillations in the wind torque owing to the first-order dynamics. Second, the generator and wind torques differ especially during wind transients subject to the conservation of angular momentum of the rotor. Third, oscillations of the power coefficient exceed the Betz limit temporarily due to the energy storage in the rotor, which acts as a temporary buffer that stores the kinetic energy like a flywheel in short durations. Last, average of transient power coefficients peaks at a smaller tip-speed ratio for wind gusts than steady winds. This work was supported by the Sabanci University Internal Research Grant Program (SU-IRG-985).

  14. Transient behavior of high-interaction MHD generator following external loading faults

    International Nuclear Information System (INIS)

    Ishikawa, Motoo

    1983-01-01

    Transient behavior consequent to external loading faults is studied numerically on four configurations of high-interaction MHD generators-subsonic Faraday, supersonic Faraday, subsonic diagonal and supersonic diagonal, to provide a variable data base to serve in selecting the type of large-scale MHD generator. Time-dependent one-dimensional Navier-Stokes equations are solved with the 1969 MacCormack method, in combination with the Maxwell equations and the generalized Ohm's law. An artificial viscosity term is added to the Navier-Stokes equations to maintain numerical stability. It is shown that, with both supersonic and subsonic flows, the Faraday generator is liable to sustain more harmful effect from short than from open faults of the external loading circuit. For large-scale diagonal types, on the other hand, open faults are more dangerous. With subsonic flow, a shock wave propagating upstream is induced by short fault in the Faraday, and by open fault in the diagonal-type generator. In the case of supersonic flow, propagation upstream of the disturbance is completely obstructed. Larger electrical stress is foreseen for Faraday than for diagonal configuration. (author)

  15. Erosion of beryllium under ITER – Relevant transient plasma loads

    International Nuclear Information System (INIS)

    Kupriyanov, I.B.; Nikolaev, G.N.; Kurbatova, L.A.; Porezanov, N.P.; Podkovyrov, V.L.; Muzichenko, A.D.; Zhitlukhin, A.M.; Gervash, A.A.; Safronov, V.M.

    2015-01-01

    Highlights: • We study the erosion, mass loss/gain and surface structure evolution of Be/CuCrZr mock-ups, armored with beryllium of TGP-56FW grade after irradiation by deuterium plasma heat load of 0.5 MJ/m 2 at 250 °C and 500 °C. • Beryllium mass loss/erosion under plasma heat load at 250 °C is rather small (no more than 0.2 g/m 2 shot and 0.11 μm/shot, correspondingly, after 40 shots) and tends to decrease with increasing number of shots. • Beryllium mass loss/erosion under plasma heat load at 500 °C is much higher (∼2.3 g/m 2 shot and 1.2 μm/shot, correspondingly, after 10 shot) and tends to decrease with increasing the number of shots (∼0.26 g/m 2 pulse and 0.14 μm/shot, correspondingly, after 100 shot). • Beryllium erosion value derived from the measurements of profile of irradiated surface is much higher than erosion value derived from mass loss data. - Abstract: Beryllium will be used as a armor material for the ITER first wall. It is expected that erosion of beryllium under transient plasma loads such as the edge-localized modes (ELMs) and disruptions will mainly determine a lifetime of the ITER first wall. This paper presents the results of recent experiments with the Russian beryllium of TGP-56FW ITER grade on QSPA-Be plasma gun facility. The Be/CuCrZr mock-ups were exposed to up to 100 shots by deuterium plasma streams (5 cm in diameter) with pulse duration of 0.5 ms and heat loads range of 0.2–0.5 MJ/m 2 at different temperature of beryllium tiles. The temperature of Be tiles has been maintained about 250 and 500 °C during the experiments. After 10, 40 and 100 shots, the beryllium mass loss/gain under erosion process were investigated as well as evolution of surface microstructure and cracks morphology

  16. Erosion of beryllium under ITER – Relevant transient plasma loads

    Energy Technology Data Exchange (ETDEWEB)

    Kupriyanov, I.B., E-mail: igkupr@gmail.com [A.A. Bochvar High Technology Research Institute of Inorganic Materials, Rogova St. 5a, 123060 Moscow (Russian Federation); Nikolaev, G.N.; Kurbatova, L.A.; Porezanov, N.P. [A.A. Bochvar High Technology Research Institute of Inorganic Materials, Rogova St. 5a, 123060 Moscow (Russian Federation); Podkovyrov, V.L.; Muzichenko, A.D.; Zhitlukhin, A.M. [TRINITI, Troitsk, Moscow reg. (Russian Federation); Gervash, A.A. [Efremov Research Institute, S-Peterburg (Russian Federation); Safronov, V.M. [Project Center of ITER, Moscow (Russian Federation)

    2015-08-15

    Highlights: • We study the erosion, mass loss/gain and surface structure evolution of Be/CuCrZr mock-ups, armored with beryllium of TGP-56FW grade after irradiation by deuterium plasma heat load of 0.5 MJ/m{sup 2} at 250 °C and 500 °C. • Beryllium mass loss/erosion under plasma heat load at 250 °C is rather small (no more than 0.2 g/m{sup 2} shot and 0.11 μm/shot, correspondingly, after 40 shots) and tends to decrease with increasing number of shots. • Beryllium mass loss/erosion under plasma heat load at 500 °C is much higher (∼2.3 g/m{sup 2} shot and 1.2 μm/shot, correspondingly, after 10 shot) and tends to decrease with increasing the number of shots (∼0.26 g/m{sup 2} pulse and 0.14 μm/shot, correspondingly, after 100 shot). • Beryllium erosion value derived from the measurements of profile of irradiated surface is much higher than erosion value derived from mass loss data. - Abstract: Beryllium will be used as a armor material for the ITER first wall. It is expected that erosion of beryllium under transient plasma loads such as the edge-localized modes (ELMs) and disruptions will mainly determine a lifetime of the ITER first wall. This paper presents the results of recent experiments with the Russian beryllium of TGP-56FW ITER grade on QSPA-Be plasma gun facility. The Be/CuCrZr mock-ups were exposed to up to 100 shots by deuterium plasma streams (5 cm in diameter) with pulse duration of 0.5 ms and heat loads range of 0.2–0.5 MJ/m{sup 2} at different temperature of beryllium tiles. The temperature of Be tiles has been maintained about 250 and 500 °C during the experiments. After 10, 40 and 100 shots, the beryllium mass loss/gain under erosion process were investigated as well as evolution of surface microstructure and cracks morphology.

  17. Dynamically-Loaded Hardware Libraries (HLL) Technology for Audio Applications

    DEFF Research Database (Denmark)

    Esposito, A.; Lomuscio, A.; Nunzio, L. Di

    2016-01-01

    In this work, we apply hardware acceleration to embedded systems running audio applications. We present a new framework, Dynamically-Loaded Hardware Libraries or HLL, to dynamically load hardware libraries on reconfigurable platforms (FPGAs). Provided a library of application-specific processors......, we load on-the-fly the specific processor in the FPGA, and we transfer the execution from the CPU to the FPGA-based accelerator. The proposed architecture provides excellent flexibility with respect to the different audio applications implemented, high quality audio, and an energy efficient solution....

  18. Excited-state dynamics of a ruthenium(II) catalyst studied by transient photofragmentation in gas phase and transient absorption in solution

    Energy Technology Data Exchange (ETDEWEB)

    Imanbaew, D.; Nosenko, Y. [Fachbereich Chemie, Technische Universität Kaiserslautern, Erwin-Schrödinger-Str. 52–54, 67663 Kaiserslautern (Germany); Forschungszentrum OPTIMAS, Erwin-Schrödinger-Str. 46, 67663 Kaiserslautern (Germany); Kerner, C. [Fachbereich Chemie, Technische Universität Kaiserslautern, Erwin-Schrödinger-Str. 52–54, 67663 Kaiserslautern (Germany); Chevalier, K.; Rupp, F. [Fachbereich Physik, Technische Universität Kaiserslautern, Erwin-Schrödinger-Str. 46, 67663 Kaiserslautern (Germany); Riehn, C., E-mail: riehn@chemie.uni-kl.de [Fachbereich Chemie, Technische Universität Kaiserslautern, Erwin-Schrödinger-Str. 52–54, 67663 Kaiserslautern (Germany); Forschungszentrum OPTIMAS, Erwin-Schrödinger-Str. 46, 67663 Kaiserslautern (Germany); Thiel, W.R. [Fachbereich Chemie, Technische Universität Kaiserslautern, Erwin-Schrödinger-Str. 52–54, 67663 Kaiserslautern (Germany); Diller, R. [Fachbereich Physik, Technische Universität Kaiserslautern, Erwin-Schrödinger-Str. 46, 67663 Kaiserslautern (Germany)

    2014-10-17

    Graphical abstract: - Highlights: • Ultrafast dynamics of new Ru(II) catalysts investigated in gas phase and solution. • Catalyst activation (HCl loss) achieved in ion trap by UV photoexcitation. • Electronic relaxation proceeds by IVR and IC followed by ground state dissociation. • No triplet formation in contrast to other Ru-polypyridine complexes. • Solvent prohibits catalyst activation in solution by fast vibrational cooling. - Abstract: We report studies on the excited state dynamics of new ruthenium(II) complexes [(η{sup 6}-cymene)RuCl(apypm)]PF{sub 6} (apypm=2-NR{sub 2}-4-(pyridine-2-yl)-pyrimidine, R=CH{sub 3} (1)/H (2)) which, in their active form [1{sup +}-HCl] and [2{sup +}-HCl], catalyze the transfer hydrogenation of arylalkyl ketones in the absence of a base. The investigations encompass femtosecond pump–probe transient mass spectrometry under isolated conditions and transient absorption spectroscopy in acetonitrile solution, both on the cations [(η{sup 6}-cymene)RuCl(apypm)]{sup +} (1{sup +}, 2{sup +}). Gas phase studies on mass selected ions were performed in an ESI ion trap mass spectrometer by transient photofragmentation, unambiguously proving the formation of the activated catalyst species [1{sup +}-HCl] or [2{sup +}-HCl] after photoexcitation being the only fragmentation channel. The primary excited state dynamics in the gas phase could be fitted to a biexponential decay, yielding time constants of <100 fs and 1–3 ps. Transient absorption spectroscopy performed in acetonitrile solution using femtosecond UV/Vis and IR probe laser pulses revealed additional deactivation processes on longer time scales (∼7–12 ps). However, the formation of the active catalyst species after photoexcitation could not be observed in solution. The results from both studies are compared to former CID investigations and DFT calculations concerning the activation mechanism.

  19. Transients drive the demographic dynamics of plant populations in variable environments

    DEFF Research Database (Denmark)

    McDonald, Jenni L; Stott, Iain; Townley, Stuart

    2016-01-01

    clear patterns related to growth form. We find a surprising tendency for plant populations to boom rather than bust in response to temporal changes in vital rates and that stochastic growth rates increase with increasing tendency to boom. Synthesis. Transient dynamics contribute significantly...

  20. Transient behaviour of a ``beam loaded`` prebuncher cavity and linac structure

    Energy Technology Data Exchange (ETDEWEB)

    Messina, Giovanni; Picardi, Luigi; Ronsivalle, Concetta; Vignati, Angelo [ENEA, Centro Ricerche Frascati, Rome (Italy)

    1997-03-01

    They present the evaluation of the effect of the beam loading on the time response of a 3 GHz prebuncher cavity to the generator and to an input 120 deg chopped electron beam for two different cavity materials. The lumped-element representation of the cavity as a parallel RLC circuit is used which allows to compute also the sensitivity of the prebuncher voltage amplitude and phase with respect to beam current fluctuations. The analysis has been extended to the transient behaviour of a linac positioned after the prebuncher cavity. The consequences of the computation results on the application of a chopper-prebuncher system in a linac devoted to the MUH FEL experiment are discussed.

  1. Floquet–Magnus theory and generic transient dynamics in periodically driven many-body quantum systems

    International Nuclear Information System (INIS)

    Kuwahara, Tomotaka; Mori, Takashi; Saito, Keiji

    2016-01-01

    This work explores a fundamental dynamical structure for a wide range of many-body quantum systems under periodic driving. Generically, in the thermodynamic limit, such systems are known to heat up to infinite temperature states in the long-time limit irrespective of dynamical details, which kills all the specific properties of the system. In the present study, instead of considering infinitely long-time scale, we aim to provide a general framework to understand the long but finite time behavior, namely the transient dynamics. In our analysis, we focus on the Floquet–Magnus (FM) expansion that gives a formal expression of the effective Hamiltonian on the system. Although in general the full series expansion is not convergent in the thermodynamics limit, we give a clear relationship between the FM expansion and the transient dynamics. More precisely, we rigorously show that a truncated version of the FM expansion accurately describes the exact dynamics for a certain time-scale. Our theory reveals an experimental time-scale for which non-trivial dynamical phenomena can be reliably observed. We discuss several dynamical phenomena, such as the effect of small integrability breaking, efficient numerical simulation of periodically driven systems, dynamical localization and thermalization. Especially on thermalization, we discuss a generic scenario on the prethermalization phenomenon in periodically driven systems. -- Highlights: •A general framework to describe transient dynamics for periodically driven systems. •The theory is applicable to generic quantum many-body systems including long-range interacting systems. •Physical meaning of the truncation of the Floquet–Magnus expansion is rigorously established. •New mechanism of the prethermalization is proposed. •Revealing an experimental time-scale for which non-trivial dynamical phenomena can be reliably observed.

  2. Floquet–Magnus theory and generic transient dynamics in periodically driven many-body quantum systems

    Energy Technology Data Exchange (ETDEWEB)

    Kuwahara, Tomotaka, E-mail: tomotaka.phys@gmail.com [Department of Physics, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan); WPI, Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Mori, Takashi [Department of Physics, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan); Saito, Keiji [Department of Physics, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, 223-8522 (Japan)

    2016-04-15

    This work explores a fundamental dynamical structure for a wide range of many-body quantum systems under periodic driving. Generically, in the thermodynamic limit, such systems are known to heat up to infinite temperature states in the long-time limit irrespective of dynamical details, which kills all the specific properties of the system. In the present study, instead of considering infinitely long-time scale, we aim to provide a general framework to understand the long but finite time behavior, namely the transient dynamics. In our analysis, we focus on the Floquet–Magnus (FM) expansion that gives a formal expression of the effective Hamiltonian on the system. Although in general the full series expansion is not convergent in the thermodynamics limit, we give a clear relationship between the FM expansion and the transient dynamics. More precisely, we rigorously show that a truncated version of the FM expansion accurately describes the exact dynamics for a certain time-scale. Our theory reveals an experimental time-scale for which non-trivial dynamical phenomena can be reliably observed. We discuss several dynamical phenomena, such as the effect of small integrability breaking, efficient numerical simulation of periodically driven systems, dynamical localization and thermalization. Especially on thermalization, we discuss a generic scenario on the prethermalization phenomenon in periodically driven systems. -- Highlights: •A general framework to describe transient dynamics for periodically driven systems. •The theory is applicable to generic quantum many-body systems including long-range interacting systems. •Physical meaning of the truncation of the Floquet–Magnus expansion is rigorously established. •New mechanism of the prethermalization is proposed. •Revealing an experimental time-scale for which non-trivial dynamical phenomena can be reliably observed.

  3. Transient dynamic and inelastic analysis of shells of revolution

    International Nuclear Information System (INIS)

    Svalbonas, V.

    1975-01-01

    Advances in the limits of structural use in the aerospace and nuclear power industries over the past years have increased the requirements upon the applicable analytical computer programs to include accurate capabilities for inelastic and transient dynamic analyses. In many minds, however, this advanced capability is unequivocally linked with the large scale, general purpose, finite element programs. This idea is also combined with the view that, therefore, such analyses are prohibitively expensive and should be relegated to the 'last resort' classification. While this, in the general sense, may indeed be the case, if however, the user needs only to analyze structures falling into limited categories, he may find that a variety of smaller special purpose programs are available, which do not put an undue strain upon his resources. One such structural category is shells of revolution. This survey of programs will concentrate upon the analytical tools which have been developed predominantly for shells of revolution. The survey will be subdivided into three parts: a) consideration of programs for transient dynamic analysis, b) consideration of programs for inelastic analysis, and finally, c) consideration of programs capable of dynamic plasticity analysis. In each part, programs based upon finite difference, finite element, and numerical integration methods will be considered. The programs will be compared on the basis of analytical capabilities, and ease of idealization and use. In each part of the survey sample problems will be utilized to exemplify the state-of-the-art. (orig.) [de

  4. Seismic safety margins research program. Project VIII load combination project: work plan

    International Nuclear Information System (INIS)

    Chou, C.K.; Vepa, K.; George, L.; Smith, P.D.

    1979-01-01

    The proposed load combination project has the following overall objectives: develop a methodology for appropriate combination of dynamic loads for nuclear power plants under normal plant operation, transients, accidents, and natural hazards; establish design criteria, load factors, and component service levels for appropriate combinations of dynamic loads or responses to be used in nuclear power plant design; determine the reliability of typical piping systems, both inside and outside the containment structure, and provide the NRC with a sound technical basis for defining the criteria for postulating pipe breaks; and determine the probabilities of a large LOCA induced directly and indirectly by a range of earthquakes

  5. Structural dynamics in FBR

    International Nuclear Information System (INIS)

    Bhoje, S.B.

    2003-01-01

    In view of thin walled large diameter shell structures with associated fluid effects, structural dynamics problems are very critical in a fast breeder reactor. Structural characteristics and consequent structural dynamics problems in typical pool type Fast Breeder Reactor are highlighted. A few important structural dynamics problems are pump induced as well as flow induced vibrations, seismic excitations, pressure transients in the intermediate heat exchangers and pipings due to a large sodium water reaction in the steam generator, and core disruptive accident loadings. The vibration problems which call for identification of excitation forces, formulation of special governing equations and detailed analysis with fluid structure interaction and sloshing effects, particularly for the components such as PSP, inner vessel, CP, CSRDM and TB are elaborated. Seismic design issues are presented in a comprehensive way. Other transient loadings which are specific to FBR, resulting from sodium-water reaction and core disruptive accident are highlighted. A few important results of theoretical as well as experimental works carried out for 500 MWe Prototype Fast Breeder Reactor (PFBR), in the domain of structural dynamics are presented. (author)

  6. Variable load failure mechanism for high-speed load sensing electro-hydrostatic actuator pump of aircraft

    Directory of Open Access Journals (Sweden)

    Cun SHI

    2018-05-01

    Full Text Available This paper presents a novel transient lubrication model for the analysis of the variable load failure mechanism of high-speed pump used in Load Sensing Electro-Hydrostatic Actuator (LS-EHA. Focusing on the slipper/swashplate pair partial abrasion, which is considered as the dominant failure mode in the high-speed condition, slipper dynamic models are established. A forth sliding motion of the slipper on the swashplate surface is presented under the fact that the slipper center of mass will rotate around the center of piston ball when the swashplate angle is dynamically adjusted. Besides, extra inertial tilting moments will be produced for the slipper based on the theorem on translation of force, which will increase rapidly when LS-EHA pump operates under high-speed condition. Then, a dynamic lubricating model coupling with fluid film thickness field, temperature field and pressure field is proposed. The deformation effects caused by thermal deflection and hydrostatic pressure are considered. A numerical simulation model is established to validate the effectiveness and accuracy of the proposed model. Finally, based on the load spectrum of aircraft flight profile, the variable load conditions and the oil film characteristics are analyzed, and series of variable load rules of oil film thickness with variable speed/variable pressure/variable displacement are concluded. Keywords: Coupling lubrication model, Electro-Hydrostatic Actuator (EHA, High-speed pump, Partial abrasion, Slipper pair, Variable load

  7. Phase-amplitude reduction of transient dynamics far from attractors for limit-cycling systems

    Science.gov (United States)

    Shirasaka, Sho; Kurebayashi, Wataru; Nakao, Hiroya

    2017-02-01

    Phase reduction framework for limit-cycling systems based on isochrons has been used as a powerful tool for analyzing the rhythmic phenomena. Recently, the notion of isostables, which complements the isochrons by characterizing amplitudes of the system state, i.e., deviations from the limit-cycle attractor, has been introduced to describe the transient dynamics around the limit cycle [Wilson and Moehlis, Phys. Rev. E 94, 052213 (2016)]. In this study, we introduce a framework for a reduced phase-amplitude description of transient dynamics of stable limit-cycling systems. In contrast to the preceding study, the isostables are treated in a fully consistent way with the Koopman operator analysis, which enables us to avoid discontinuities of the isostables and to apply the framework to system states far from the limit cycle. We also propose a new, convenient bi-orthogonalization method to obtain the response functions of the amplitudes, which can be interpreted as an extension of the adjoint covariant Lyapunov vector to transient dynamics in limit-cycling systems. We illustrate the utility of the proposed reduction framework by estimating the optimal injection timing of external input that efficiently suppresses deviations of the system state from the limit cycle in a model of a biochemical oscillator.

  8. Transient Dynamics of Electric Power Systems: Direct Stability Assessment and Chaotic Motions

    Science.gov (United States)

    Chu, Chia-Chi

    A power system is continuously experiencing disturbances. Analyzing, predicting, and controlling transient dynamics, which describe transient behaviors of the power system following disturbances, is a major concern in the planning and operation of a power utility. Important conclusions and decisions are made based on the result of system transient behaviors. As today's power network becomes highly interconnected and much more complex, it has become essential to enhance the fundamental understanding of transient dynamics, and to develop fast and reliable computational algorithms. In this thesis, we emphasize mathematical rigor rather than physical insight. Nonlinear dynamical system theory is applied to study two fundamental topics: direct stability assessment and chaotic motions. Conventionally, power system stability is determined by calculating the time-domain transient behaviors for a given disturbance. In contrast, direct methods identify whether or not the system will remain stable once the disturbance is removed by comparing the corresponding energy value of the post-fault system to a calculated threshold value. Direct methods not only avoid the time-consuming numerical integration of the time domain approach, but also provide a quantitative measure of the degree of system stability. We present a general framework for the theoretical foundations of direct methods. Canonical representations of network-reduction models as well as network-preserving models are proposed to facilitate the analysis and the construction of energy functions of various power system models. An advanced and practical method, called the boundary of stability region based controlling unstable equilibrium point method (BCU method), of computing the controlling unstable equilibrium point is proposed along with its theoretical foundation. Numerical solution algorithms capable of supporting on-line applications of direct methods are provided. Further possible improvements and enhancements are

  9. Effect of stationary high heat flux and transient ELMs-like heat loads on the divertor PFCs

    Energy Technology Data Exchange (ETDEWEB)

    Riccardi, B., E-mail: bruno.riccardi@f4e.europa.eu [Fusion for Energy, ITER Department, Josep Pla, 2, Torres Diagonal Litoral B3, 08019 Barcelona (Spain); Gavila, P. [Fusion for Energy, ITER Department, Josep Pla, 2, Torres Diagonal Litoral B3, 08019 Barcelona (Spain); Giniatulin, R. [Efremov Institute, 196641 St. Petersburg (Russian Federation); Kuznetsov, V. [SRC RF TRINITI, ul. Pushkovykh, vladenie 12, 142190 Troitsk, Moscow Region (Russian Federation); Rulev, R. [Efremov Institute, 196641 St. Petersburg (Russian Federation); Klimov, N.; Kovalenko, D.; Barsuk, V. [SRC RF TRINITI, ul. Pushkovykh, vladenie 12, 142190 Troitsk, Moscow Region (Russian Federation); Koidan, V.; Korshunov, S. [NRC “Kurchatov Institute”, Moscow (Russian Federation)

    2013-10-15

    The experimental evaluation of the divertor plasma facing components (PFCs) lifetime under transient events, such as edge localized modes (ELMs) and high heat flux (HHF) thermal fatigue expected during ITER normal operations and slow transient events is here presented. The experiments have been performed in the frame of an EU/RF collaboration. For carbon fiber composite material the erosion is caused by PAN fiber damage whilst the erosion of tungsten is determined by the melt layer movement and crack formation. The conclusion of this study is that, in addition to the structural change produced in the armor materials by ELMs-like loads, some mock ups showed also a degradation of the thermal fatigue performances.

  10. PPOOLEX experiments on dynamic loading with pressure feedback

    International Nuclear Information System (INIS)

    Puustinen, M.; Laine, J.; Raesaenen, A.

    2011-01-01

    This report summarizes the results of the dynamic loading experiments (DYN series) carried out with the scaled down, two compartment PPOOLEX test facility designed and constructed at LUT. Steam was blown into the dry well compartment and from there through the DN200 vertical blowdown pipe to the condensation pool filled with sub-cooled water. The main purpose of the experiments was to study dynamic loads caused by different condensation modes. Particularly, the effect of counterpressure on loads due to pressure oscillations induced by chugging was of interest. Before the experiments the condensation pool was filled with isothermal water so that the blowdown pipe outlet was submerged by 1.03-1.11 m. The initial temperature of the pool water varied from 11 deg. C to 63 deg. C, the steam flow rate from 290 g/s to 1220 g/s and the temperature of incoming steam from 132 deg. C to 182 deg. C. Non-condensables were pushed from the dry well into the gas space of the wet well with a short discharge of steam before the recorded period of the experiments. As a result of this procedure, the system pressure was at an elevated level in the beginning of the actual experiments. An increased counterpressure was used in the last experiment of the series. The diminishing effect of increased system pressure on chugging intensity and on measured loads is evident from the results of the last experiment. The highest pressure pulses both inside the blowdown pipe and in the condensation pool were about half of those measured with a lower system pressure but otherwise with similar test parameters. The experiments on dynamic loading gave expected results. The loads experienced by pool structures depended strongly on the steam mass flow rate, pool water temperature and system pressure. The DYN experiments indicated that chugging and condensation within the blowdown pipe cause significant dynamic loads in case of strongly sub-cooled pool water. The level of pool water temperature is decisive

  11. PPOOLEX experiments on dynamic loading with pressure feedback

    Energy Technology Data Exchange (ETDEWEB)

    Puustinen, M.; Laine, J.; Raesaenen, A. (Lappeenranta Univ. of Technology, Nuclear Safety Research Unit (Finland))

    2011-01-15

    This report summarizes the results of the dynamic loading experiments (DYN series) carried out with the scaled down, two compartment PPOOLEX test facility designed and constructed at LUT. Steam was blown into the dry well compartment and from there through the DN200 vertical blowdown pipe to the condensation pool filled with sub-cooled water. The main purpose of the experiments was to study dynamic loads caused by different condensation modes. Particularly, the effect of counterpressure on loads due to pressure oscillations induced by chugging was of interest. Before the experiments the condensation pool was filled with isothermal water so that the blowdown pipe outlet was submerged by 1.03-1.11 m. The initial temperature of the pool water varied from 11 deg. C to 63 deg. C, the steam flow rate from 290 g/s to 1220 g/s and the temperature of incoming steam from 132 deg. C to 182 deg. C. Non-condensables were pushed from the dry well into the gas space of the wet well with a short discharge of steam before the recorded period of the experiments. As a result of this procedure, the system pressure was at an elevated level in the beginning of the actual experiments. An increased counterpressure was used in the last experiment of the series. The diminishing effect of increased system pressure on chugging intensity and on measured loads is evident from the results of the last experiment. The highest pressure pulses both inside the blowdown pipe and in the condensation pool were about half of those measured with a lower system pressure but otherwise with similar test parameters. The experiments on dynamic loading gave expected results. The loads experienced by pool structures depended strongly on the steam mass flow rate, pool water temperature and system pressure. The DYN experiments indicated that chugging and condensation within the blowdown pipe cause significant dynamic loads in case of strongly sub-cooled pool water. The level of pool water temperature is decisive

  12. Current interruption transients calculation

    CERN Document Server

    Peelo, David F

    2014-01-01

    Provides an original, detailed and practical description of current interruption transients, origins, and the circuits involved, and how they can be calculated Current Interruption Transients Calculationis a comprehensive resource for the understanding, calculation and analysis of the transient recovery voltages (TRVs) and related re-ignition or re-striking transients associated with fault current interruption and the switching of inductive and capacitive load currents in circuits. This book provides an original, detailed and practical description of current interruption transients, origins,

  13. Investigation of transient dynamics of capillary assisted particle assembly yield

    Energy Technology Data Exchange (ETDEWEB)

    Virganavičius, D. [Institute of Materials Science, Kaunas University of Technology, K. Baršausko St. 59, Kaunas LT-51423 (Lithuania); Laboratory of Micro- and Nanotechnology, Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Juodėnas, M. [Institute of Materials Science, Kaunas University of Technology, K. Baršausko St. 59, Kaunas LT-51423 (Lithuania); Tamulevičius, T., E-mail: tomas.tamulevicius@ktu.lt [Institute of Materials Science, Kaunas University of Technology, K. Baršausko St. 59, Kaunas LT-51423 (Lithuania); Department of Physics, Kaunas University of Technology, Studentų St. 50, Kaunas LT-51368 (Lithuania); Schift, H. [Laboratory of Micro- and Nanotechnology, Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Tamulevičius, S. [Institute of Materials Science, Kaunas University of Technology, K. Baršausko St. 59, Kaunas LT-51423 (Lithuania); Department of Physics, Kaunas University of Technology, Studentų St. 50, Kaunas LT-51368 (Lithuania)

    2017-06-01

    Highlights: • Regular particles arrays were assembled by capillary force assisted deposition. • Deposition yield dynamics was investigated at different thermal velocity regimes. • Yield transient behavior was approximated with logistic function. • Pattern density influence for switching behavior was assessed. - Abstract: In this paper, the transient behavior of the particle assembly yield dynamics when switching from low yield to high yield deposition at different velocity and thermal regimes is investigated. Capillary force assisted particle assembly (CAPA) using colloidal suspension of green fluorescent 270 nm diameter polystyrene beads was performed on patterned poly (dimethyl siloxane) substrates using a custom-built deposition setup. Two types of patterns with different trapping site densities were used to assess CAPA process dynamics and the influence of pattern density and geometry on the deposition yield transitions. Closely packed 300 nm diameter circular pits ordered in hexagonal arrangement with 300 nm pitch, and 2 × 2 mm{sup 2} square pits with 2 μm spacing were used. 2-D regular structures of the deposited particles were investigated by means of optical fluorescence and scanning electron microscopy. The fluorescence micrographs were analyzed using a custom algorithm enabling to identify particles and calculate efficiency of the deposition performed at different regimes. Relationship between the spatial distribution of particles in transition zone and ambient conditions was evaluated and quantified by approximation of the yield profile with a logistic function.

  14. Dynamic modeling and analysis of load sharing characteristics of wind turbine gearbox

    Directory of Open Access Journals (Sweden)

    Pengxing Yi

    2015-03-01

    Full Text Available A coupled dynamic model, which contains helical gears-shafts-bearings for a wind turbine gearbox transmission system, was built considering nonlinear factors of the time-varying mesh stiffness, the external varying load, and the dynamic transmission error at first. The model is confirmed to be right after comparing the theoretical data with the experimental load sharing values, and also it is found that the static load sharing is conservative to evaluate the non-equilibrium effect of a planetary gear system. Besides, the analyzing results of the influence of average error and amplitude error on the load sharing show that the load sharing could be decreased if the error goes up a little. Then, by means of treating the static tracing point as the dynamic initial values, we analyzed the initial position’s influence on the load sharing of transmission system to provide a theoretical basis of load sharing control. Furthermore, we explored the influence of high-speed shaft position angle on the load sharing and the dynamic load factor of gears fixed on the parallel shafts. The results provide useful theoretical guidelines for the design of parallel shaft gear system in the wind turbines.

  15. A neural model for transient identification in dynamic processes with 'don't know' response

    International Nuclear Information System (INIS)

    Mol, Antonio C. de A.; Martinez, Aquilino S.; Schirru, Roberto

    2003-01-01

    This work presents an approach for neural network based transient identification which allows either dynamic identification or a 'don't know' response. The approach uses two 'jump' multilayer neural networks (NN) trained with the backpropagation algorithm. The 'jump' network is used because it is useful to dealing with very complex patterns, which is the case of the space of the state variables during some abnormal events. The first one is responsible for the dynamic identification. This NN uses, as input, a short set (in a moving time window) of recent measurements of each variable avoiding the necessity of using starting events. The other one is used to validate the instantaneous identification (from the first net) through the validation of each variable. This net is responsible for allowing the system to provide a 'don't know' response. In order to validate the method, a Nuclear Power Plant (NPP) transient identification problem comprising 15 postulated accidents, simulated for a pressurized water reactor (PWR), was proposed in the validation process it has been considered noisy data in order to evaluate the method robustness. Obtained results reveal the ability of the method in dealing with both dynamic identification of transients and correct 'don't know' response. Another important point studied in this work is that the system has shown to be independent of a trigger signal which indicates the beginning of the transient, thus making it robust in relation to this limitation

  16. Feedback control systems for non-linear simulation of operational transients in LMFBRs

    International Nuclear Information System (INIS)

    Khatib-Rahbar, M.; Agrawal, A.K.; Srinivasan, E.S.

    1979-01-01

    Feedback control systems for non-linear simulation of operational transients in LMFBRs are developed. The models include (1) the reactor power control and rod drive mechanism, (2) sodium flow control and pump drive system, (3) steam generator flow control and valve actuator dynamics, and (4) the supervisory control. These models have been incorporated into the SSC code using a flexible approach, in order to accommodate some design dependent variations. The impact of system nonlinearity on the control dynamics is shown to be significant for severe perturbations. Representative result for a 10 cent and 25 cent step insertion of reactivity and a 10% ramp change in load in 40 seconds demonstrate the suitability of this model for study of operational transients without scram in LMFBRs

  17. Disruptions, loads, and dynamic response of ITER

    International Nuclear Information System (INIS)

    Nelson, B.; Riemer, B.; Sayer, R.; Strickler, D.; Barabaschi, P.; Ioki, K.; Johnson, G.; Shimizu, K.; Williamson, D.

    1995-01-01

    Plasma disruptions and the resulting electromagnetic loads are critical to the design of the vacuum vessel and in-vessel components of the International Thermonuclear Experimental Reactor (ITER). This paper describes the status of plasma disruption simulations and related analysis, including the dynamic response of the vacuum vessel and in-vessel components, stresses and deflections in the vacuum vessel, and reaction loads in the support structures

  18. Incorporating moving dynamic tyre loads in pavement design and analysis

    CSIR Research Space (South Africa)

    Steyn, WJvdM

    2000-07-01

    Full Text Available at the University of Pretoria. 4 REAL LIFE TYRE LOADS Characterisation Pavement loading has been shown by various authors to be a dynamic (time-dependent) phenomenon (Divine, 1997; Cebon, 1999). A pavement experiences a vehicle as a moving, time-varying set... frequencies. Body bounce generally dominates the dynamic loading, and is mainly caused by the response of the sprung mass of the vehicle to the pavement roughness. Axle hop becomes more significant at higher vehicle speeds and higher pavement roughnesses...

  19. The Pneumatic Actuators As Vertical Dynamic Load Simulators On Medium Weighted Wheel Suspension Mechanism

    Science.gov (United States)

    Ka'ka, Simon; Himran, Syukri; Renreng, Ilyas; Sutresman, Onny

    2018-02-01

    Almost all of road damage can be caused by dynamic loads of vehicles that fluctuate according to the type of vehicle that passes through. This study aims to calculate the vertical dynamic load of the vehicle actually occurs on road construction by the mechanism of vehicle wheel suspension. Pneumatic cylinders driven by pressurized air directly load the spring and shock absorber installed on the wheels of the vehicle. The load fluctuations of the medium weight categorized vehicles are determined by the regulation of the amount of pressurized air that enters into the pneumatic cylinder chamber, pushing the piston and connecting rods. The displacement that occurs during compression on the spring and shock absorber, is substituted into the equation of vehicle dynamic load while taking into account the spring stiffness constant, and the fluid or damper gas coefficient. The results show that the magnitude of the displacement when the compression force works has significant influences to the amount of vertical dynamic load of the vehicle that overlies the road construction. The presence of dynamic load of vehicles that fluctuates and repeats, also affects on the reduction of road ability to receive the load. Experimental results using pneumatic actuators instead of real dynamic vehicle loads illustrate the characteristics of the relationship between work pressure and dynamic load. If the working pressure of P2 (bar) is greater, the vertical dynamic load Ft (N) that overloads the road structure is also greater. The associate graphs show that the shock absorber has a greater ability to reduce dynamic load vertically that burden the road structure when compared with the ability of screw spring.

  20. Effect of loading rate on dynamic fracture of reaction bonded silicon nitride

    Science.gov (United States)

    Liaw, B. M.; Kobayashi, A. S.; Emery, A. F.

    1986-01-01

    Wedge-loaded, modified tapered double cantilever beam (WL-MTDCB) specimens under impact loading were used to determine the room temperature dynamic fracture response of reaction bonded silicon nitride (RBSN). The crack extension history, with the exception of the terminal phase, was similar to that obtained under static loading. Like its static counterpart, a distinct crack acceleration phase, which was not observed in dynamic fracture of steel and brittle polymers, was noted. Unlike its static counterpart, the crack continued to propagate at nearly its terminal velocity under a low dynamic stress intensity factor during the terminal phase of crack propagation. These and previously obtained results for glass and RBSN show that dynamic crack arrest under a positive dynamic stress intensity factor is unlikely in static and impact loaded structural ceramics.

  1. Floquet-Magnus theory and generic transient dynamics in periodically driven many-body quantum systems

    Science.gov (United States)

    Kuwahara, Tomotaka; Mori, Takashi; Saito, Keiji

    2016-04-01

    This work explores a fundamental dynamical structure for a wide range of many-body quantum systems under periodic driving. Generically, in the thermodynamic limit, such systems are known to heat up to infinite temperature states in the long-time limit irrespective of dynamical details, which kills all the specific properties of the system. In the present study, instead of considering infinitely long-time scale, we aim to provide a general framework to understand the long but finite time behavior, namely the transient dynamics. In our analysis, we focus on the Floquet-Magnus (FM) expansion that gives a formal expression of the effective Hamiltonian on the system. Although in general the full series expansion is not convergent in the thermodynamics limit, we give a clear relationship between the FM expansion and the transient dynamics. More precisely, we rigorously show that a truncated version of the FM expansion accurately describes the exact dynamics for a certain time-scale. Our theory reveals an experimental time-scale for which non-trivial dynamical phenomena can be reliably observed. We discuss several dynamical phenomena, such as the effect of small integrability breaking, efficient numerical simulation of periodically driven systems, dynamical localization and thermalization. Especially on thermalization, we discuss a generic scenario on the prethermalization phenomenon in periodically driven systems.

  2. The choice of dynamic amplification factors for the ITER generic port plugs during disruptions

    International Nuclear Information System (INIS)

    Vacas, Christian; Rodriguez, Eduardo; Guirao, Julio; Iglesias, Silvia; Udintsev, Victor; Pak, Sunil; Maquet, Philippe; Roces, Jorge; Casal, Natalia

    2015-01-01

    Highlights: • Dynamic amplification factor is largely influenced by the DFWs geometry and for the type of bond between DFW and DSM. • DAF were calculated by analyzing the deformed shape and not just looking at the absolute values of displacements. • Detailed transient time history non-linear analysis of an MDUP II electro magnetic event has been carried out. • Cuasi-constant damping ratio of 3% has been considered using a generalized proportional damping model. - Abstract: The purpose of this paper is present an overview of the methodology followed to calculate the dynamic amplification factors applied to the electromagnetic loads acting in the ITER generic port plugs. The methodology used for combining an EM transient event with another kind of load is based in the treated of this dynamic EM event as a static load. As first stage a transient dynamic analysis was performed, at the most demanded electromagnetic event [2], to determine the dynamic response of the port plugs. In the same way, have been solved all the time steps of the dynamic event as static loads, it means that the inertial effect has been neglected. The response of each time-step at the dynamic solution has been compared with the same time-step solved as a static load. For this purpose some control points were positioned along the structure at the most representative locations. The key of these calculations is the understanding of the deformed modes affecting the port plug in order to obtain a reasonable dynamic amplification factors that permit the characterization of these loads in a realistic way and does not derive in a too conservative approach. Additionally, the fundamental frequencies and vibration modes of the generic port plug, requested for the characterization of the damping effects at the structure, were calculated in a complementary modal analysis performed for this aim.

  3. Simulating transient dynamics of the time-dependent time fractional Fokker–Planck systems

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Yan-Mei, E-mail: ymkang@mail.xjtu.edu.cn

    2016-09-16

    For a physically realistic type of time-dependent time fractional Fokker–Planck (FP) equation, derived as the continuous limit of the continuous time random walk with time-modulated Boltzmann jumping weight, a semi-analytic iteration scheme based on the truncated (generalized) Fourier series is presented to simulate the resultant transient dynamics when the external time modulation is a piece-wise constant signal. At first, the iteration scheme is demonstrated with a simple time-dependent time fractional FP equation on finite interval with two absorbing boundaries, and then it is generalized to the more general time-dependent Smoluchowski-type time fractional Fokker–Planck equation. The numerical examples verify the efficiency and accuracy of the iteration method, and some novel dynamical phenomena including polarized motion orientations and periodic response death are discussed. - Highlights: • An iteration method is proposed for the transient dynamics of time-dependent time fractional Fokker–Planck equations. • The method is based on Fourier Series solution and the multi-step transition probability formula. • With the time-modulated subdiffusion on finite interval as example, the polarized motion orientation is disclosed. • With the time-modulated subdiffusion within a confined potential as example, the death of dynamic response is observed.

  4. Simulating transient dynamics of the time-dependent time fractional Fokker–Planck systems

    International Nuclear Information System (INIS)

    Kang, Yan-Mei

    2016-01-01

    For a physically realistic type of time-dependent time fractional Fokker–Planck (FP) equation, derived as the continuous limit of the continuous time random walk with time-modulated Boltzmann jumping weight, a semi-analytic iteration scheme based on the truncated (generalized) Fourier series is presented to simulate the resultant transient dynamics when the external time modulation is a piece-wise constant signal. At first, the iteration scheme is demonstrated with a simple time-dependent time fractional FP equation on finite interval with two absorbing boundaries, and then it is generalized to the more general time-dependent Smoluchowski-type time fractional Fokker–Planck equation. The numerical examples verify the efficiency and accuracy of the iteration method, and some novel dynamical phenomena including polarized motion orientations and periodic response death are discussed. - Highlights: • An iteration method is proposed for the transient dynamics of time-dependent time fractional Fokker–Planck equations. • The method is based on Fourier Series solution and the multi-step transition probability formula. • With the time-modulated subdiffusion on finite interval as example, the polarized motion orientation is disclosed. • With the time-modulated subdiffusion within a confined potential as example, the death of dynamic response is observed.

  5. Effects of static pre-loading on the dynamic stability of a column on ...

    African Journals Online (AJOL)

    This paper presents, from strictly analytical consideration, the dynamic analysis of a finite column stressed by a step load but in the presence of a previously imposed static load. The results show that (a) the dynamic buckling load for this type of loading is relatively higher than that of a similar column stressed by a step load ...

  6. Behavior of Brittle Materials Under Dynamic Loading

    National Research Council Canada - National Science Library

    Kanel, G

    2000-01-01

    Dynamic loading of brittle materials is related to many applications, including explosive excavation of rocks, design of ceramic armor, meteor impact on spacecraft windows, particle damage to turbine blades, etc...

  7. Transient heat transfer into superfluid helium under confined conditions

    International Nuclear Information System (INIS)

    Filippov, Yu.P.; Miklyaev, V.M.; Sergeev, I.A.

    1988-01-01

    Transient thermal processes at solid-HeII interface at input of step pulse of heat load was investigated. Particular attention is given to the study of influence of geometry of experimental specimen upon the heat transfer dynamics. Abrupt breakdown of highly efficient transfer modes caused by the developmet of superfluid turbulence under confined condition is revealed, and accompanying temperature shift is registered. Some characteristic parameters are selected, their dependence on experimental conditions is established

  8. Estimation of changes in dynamic hydraulic force in a magnetically suspended centrifugal blood pump with transient computational fluid dynamics analysis.

    Science.gov (United States)

    Masuzawa, Toru; Ohta, Akiko; Tanaka, Nobuatu; Qian, Yi; Tsukiya, Tomonori

    2009-01-01

    The effect of the hydraulic force on magnetically levitated (maglev) pumps should be studied carefully to improve the suspension performance and the reliability of the pumps. A maglev centrifugal pump, developed at Ibaraki University, was modeled with 926 376 hexahedral elements for computational fluid dynamics (CFD) analyses. The pump has a fully open six-vane impeller with a diameter of 72.5 mm. A self-bearing motor suspends the impeller in the radial direction. The maximum pressure head and flow rate were 250 mmHg and 14 l/min, respectively. First, a steady-state analysis was performed using commercial code STAR-CD to confirm the model's suitability by comparing the results with the real pump performance. Second, transient analysis was performed to estimate the hydraulic force on the levitated impeller. The impeller was rotated in steps of 1 degrees using a sliding mesh. The force around the impeller was integrated at every step. The transient analysis revealed that the direction of the radial force changed dynamically as the vane's position changed relative to the outlet port during one circulation, and the magnitude of this force was about 1 N. The current maglev pump has sufficient performance to counteract this hydraulic force. Transient CFD analysis is not only useful for observing dynamic flow conditions in a centrifugal pump but is also effective for obtaining information about the levitation dynamics of a maglev pump.

  9. Dynamic characteristics of an automotive fuel cell system for transitory load changes

    DEFF Research Database (Denmark)

    Rabbani, Raja Abid; Rokni, Masoud

    2013-01-01

    A dynamic model of Polymer Electrolyte Membrane Fuel Cell (PEMFC) system is developed to investigate the behavior and transient response of a fuel cell system for automotive applications. Fuel cell dynamics are subjected to reactant flows, heat management and water transportation inside the fuel...

  10. Current scaling of axially radiated power in dynamic hohlraums and dynamic hohlraum load design for ZR

    International Nuclear Information System (INIS)

    Mock, Raymond Cecil; Nash, Thomas J.; Sanford, Thomas W. L.

    2007-01-01

    We present designs for dynamic hohlraum z-pinch loads on the 28 MA, 140 ns driver ZR. The scaling of axially radiated power with current in dynamic hohlraums is reviewed. With adequate stability on ZR this scaling indicates that 30 TW of axially radiated power should be possible. The performance of the dynamic hohlraum load on the 20 MA, 100 ns driver Z is extensively reviewed. The baseline z-pinch load on Z is a nested tungsten wire array imploding onto on-axis foam. Data from a variety of x-ray diagnostics fielded on Z are presented. These diagnostics include x-ray diodes, bolometers, fast x-ray imaging cameras, and crystal spectrometers. Analysis of these data indicates that the peak dynamic radiation temperature on Z is between 250 and 300 eV from a diameter less than 1 mm. Radiation from the dynamic hohlraum itself or from a radiatively driven pellet within the dynamic hohlraum has been used to probe a variety of matter associated with the dynamic hohlraum: the tungsten z-pinch itself, tungsten sliding across the end-on apertures, a titanium foil over the end aperture, and a silicon aerogel end cap. Data showing the existence of asymmetry in radiation emanating from the two ends of the dynamic hohlraum is presented, along with data showing load configurations that mitigate this asymmetry. 1D simulations of the dynamic hohlraum implosion are presented and compared to experimental data. The simulations provide insight into the dynamic hohlraum behavior but are not necessarily a reliable design tool because of the inherently 3D behavior of the imploding nested tungsten wire arrays

  11. Dynamic intelligent cleaning model of dirty electric load data

    International Nuclear Information System (INIS)

    Zhang Xiaoxing; Sun Caixin

    2008-01-01

    There are a number of dirty data in the load database derived from the supervisory control and data acquisition (SCADA) system. Thus, the data must be carefully and reasonably adjusted before it is used for electric load forecasting or power system analysis. This paper proposes a dynamic and intelligent data cleaning model based on data mining theory. Firstly, on the basis of fuzzy soft clustering, the Kohonen clustering network is improved to fulfill the parallel calculation of fuzzy c-means soft clustering. Then, the proposed dynamic algorithm can automatically find the new clustering center (the characteristic curve of the data) with the updated sample data; At last, it is composed with radial basis function neural network (RBFNN), and then, an intelligent adjusting model is proposed to identify the dirty data. The rapid and dynamic performance of the model makes it suitable for real time calculation, and the efficiency and accuracy of the model is proved by test results of electrical load data analysis in Chongqing

  12. The assessment of RELAP5/MOD2 based on pressurizer transient experiments

    International Nuclear Information System (INIS)

    Xue Hanjun; Tanrikut, A.; Menzel, R.

    1992-03-01

    Two typical experiments have been performed in Chinese test facility under full pressure load corresponding to typical PWRs, 1) dynamic behavior of pressurizer due to relief valve operations (Case-I) is extremely important in transients and accident conditions regarding depressurization of PWR primary system; 2) Outsurge/Insurge operation is one of the transient which is often encountered and experienced in pressurizer systems due to pressure transients in primary system of PWRs. The simulation capability of RELAP5/MOD2 is good in comparison to experimental results. The physical models (such as interface model, stratification model), playing a major role in such simulation, seems to be realistic. The effect of realistic valve modeling in depressurization simulation is extremely important. Sufficient data for relief valve (the dynamic characteristics of valve) play a major role. The time dependent junction model and the trip valve model with a reduced discharge coefficient of 0.2 give better predictions in agreement with the experiment data while the trip valve models with discharge coefficient 1.0 yield overdepressurization. The simulation of outsurge/insurge transient yields satisfactory results. The thermal non-equilibrium model is important with respect to simulation of complicated physical phenomena in outsurge/insurge transient but has a negligible effect upon the depressurization simulation. (orig./HP)

  13. Material properties under intensive dynamic loading

    CERN Document Server

    Cherne, Frank J; Zhernokletov, Mikhail V; Glushak, B L; Zocher, Marvin A

    2007-01-01

    Understanding the physical and thermomechanical response of materials subjected to intensive dynamic loading is a challenge of great significance in engineering today. This volume assumes the task of gathering both experimental and diagnostic methods in one place, since not much information has been previously disseminated in the scientific literature.

  14. Numerical evaluation of cracked pipes under dynamic loading

    International Nuclear Information System (INIS)

    Petit, M.; Jamet, P.

    1989-01-01

    In order to apply the leak-before-break concept to piping systems, the behavior of cracked pipes under dynamic, and especially seismic, loadings must be studied. A simple finite element model of a cracked pipe has been developed and implemented in the general purpose computer code CASTEM 2000. The model is a generalization of the approach proposed by Paris and Tada (1). Considered loads are bending moment and axial force (representing thermal expansion and internal pressure.) The elastic characteristics of the model are determined using the Zahoor formulae for the geometry-dependent factors. Owing to the material behabior plasticity must be taken into account. To represent the crack growth, the material is defined by two characteristic values: J 1c which is the level of energy corresponding to crack initiation and the tearing modulus, T, which governs the length of propagation of the crack. For dynamic loads, unilateral conditions are imposed to represent crack closure. The model has been used for the design of dynamic tests to be conducted on shaking tables. Test principle is briefly described and numerical results are presented. Finally evaluation of margin, due to plasticity, in comparison with the standard design procedure is made

  15. The joy of transient chaos

    Energy Technology Data Exchange (ETDEWEB)

    Tél, Tamás [Institute for Theoretical Physics, Eötvös University, and MTA-ELTE Theoretical Physics Research Group, Pázmány P. s. 1/A, Budapest H-1117 (Hungary)

    2015-09-15

    We intend to show that transient chaos is a very appealing, but still not widely appreciated, subfield of nonlinear dynamics. Besides flashing its basic properties and giving a brief overview of the many applications, a few recent transient-chaos-related subjects are introduced in some detail. These include the dynamics of decision making, dispersion, and sedimentation of volcanic ash, doubly transient chaos of undriven autonomous mechanical systems, and a dynamical systems approach to energy absorption or explosion.

  16. The joy of transient chaos.

    Science.gov (United States)

    Tél, Tamás

    2015-09-01

    We intend to show that transient chaos is a very appealing, but still not widely appreciated, subfield of nonlinear dynamics. Besides flashing its basic properties and giving a brief overview of the many applications, a few recent transient-chaos-related subjects are introduced in some detail. These include the dynamics of decision making, dispersion, and sedimentation of volcanic ash, doubly transient chaos of undriven autonomous mechanical systems, and a dynamical systems approach to energy absorption or explosion.

  17. Dynamical prediction and pattern mapping in short-term load forecasting

    Energy Technology Data Exchange (ETDEWEB)

    Aguirre, Luis Antonio; Rodrigues, Daniela D.; Lima, Silvio T. [Departamento de Engenharia Eletronica, Universidade Federal de Minas Gerais, Av. Antonio Carlos, 6627, 31270-901 Belo Horizonte, MG (Brazil); Martinez, Carlos Barreira [Departamento de Engenharia Hidraulica e Recursos Hidricos, Universidade Federal de Minas Gerais, Av. Antonio Carlos, 6627, 31270-901 Belo Horizonte, MG (Brazil)

    2008-01-15

    This work will not put forward yet another scheme for short-term load forecasting but rather will provide evidences that may improve our understanding about fundamental issues which underlay load forecasting problems. In particular, load forecasting will be decomposed into two main problems, namely dynamical prediction and pattern mapping. It is argued that whereas the latter is essentially static and becomes nonlinear when weekly features in the data are taken into account, the former might not be deterministic at all. In such cases there is no determinism (serial correlations) in the data apart from the average cycle and the best a model can do is to perform pattern mapping. Moreover, when there is determinism in addition to the average cycle, the underlying dynamics are sometimes linear, in which case there is no need to resort to nonlinear models to perform dynamical prediction. Such conclusions were confirmed using real load data and surrogate data analysis. In a sense, the paper details and organizes some general beliefs found in the literature on load forecasting. This sheds some light on real model-building and forecasting problems and helps understand some apparently conflicting results reported in the literature. (author)

  18. Decrease of dynamic loads in mobile energy means

    Science.gov (United States)

    Polivaev, O. I.; Gorban, L. K.; Vorohobin, A. V.; Vedrinsky, O. S.

    2018-03-01

    The increase in the productivity of machine and tractor units is possible due to the increase in operating speeds, this leads to the emergence of increased dynamic loads in the system “engine-transmission-propulsion unit-soil”, which worsens the performance of machine-tractor aggregates. To reduce fluctuations in the “engine-transmission” system, special vibration dampers are used, which installed in close proximity to the engine and protect well the transmission from uneven engine operation; however, such dampers practically do not eliminate the oscillations of external loads. Reducing dynamic loads on the transmission and the mobile power engine (MPE) is an important issue directly related to improving the performance, reliability and durability of the tractor, as well as reducing the slippage of the drive wheels. In order to reduce effectively dynamic loads on the transmission and on the MPE, it is necessary to introduce resilient damping elements closer to the sources of oscillations, namely, to the driving wheels. At the same time, the elastic-damping element should provide accumulation of vibration energy caused by external influences and have a large energy capacity. The installation of an elastic-damping element in the final link of the tractor transmission ensures a reduction in the magnitude of external influences, thereby protecting the engine and transmission from large dynamic loads, and allows one to reduce the slippage of the propellers, which has a positive effect on the traction and energy characteristics of the tractor. Traction tests of the LTP-55 tractor on a concrete road showed that the use of an elasto-damping drive makes it possible to increase the maximum tractive power from 33.5 to 35.3 kW and to reduce the slipping of propellers by 12-30%, the specific fuel consumption by 6-10%. When driving on stubble, the use of an elastic-damping drive increases the maximum tractive power from 25 to 26 kW, reduces the skidding of propellers by

  19. Design of dynamic loading support on high temperature pipe

    International Nuclear Information System (INIS)

    Sitandung, Y.B.; Bandriyana, B.

    2002-01-01

    As a follow up to pipe stress analysis result caused by high temperature operation loading, a design of dynamic loading support was made. The type of variable and constant support as acceptable choosing are applicated for reduce of over stress and over load on piping system. Analysis line schedule of AP600 as an example with apply three dynamic loading support (two type variable and one type constant support). The pre-design of the third support above are based on analysis result with follow the support catalog and field condition wherein its supports are installed. To guarantee the performance and accurate of the support, checking is performed for spring working rate tolerance, support variability and swing angle. The design results of variable spring are loads, size, working rate, type tolerance, spring rate, variability, long and sway angle with each values 5000; 15; 1,25; VM; 0.655; 1080; 0.114; 114,5; 0,48 for S1 and 2045; 12; 0,583; VS; 0,237; 900; 0,132; 130; 0,34 for S3

  20. Calculation of piping loads due to filling procedures

    International Nuclear Information System (INIS)

    Swidersky, Harald; Thiele, Thomas

    2012-01-01

    Filling procedures in piping systems are usually not load cases that are studied by fluid dynamic and structure dynamic analyses with respect to the integrity of pipes and supports. Although, their frequency is higher than that of postulated accidental transients, therefore they have to be considered for fatigue analyses. The piping and support loads due to filling procedures are caused by the density differences if the transported fluids, for instance in flows with the transport of gas bubbles. The impact duration of the momentum forces is defined by the flow velocity and the length of discontinuities in the piping segments. Filling procedures end very often with a shock pressure, caused by the impact and decelerating of the fluid front at smaller cross sections. The suitability of the thermally hydraulics program RELAP/MOD3.3 for the calculation of realistic loads from filling procedures was studied, the results compared with experimental data. It is shown that dependent on the discretization level the loads are partial significantly underestimated.

  1. Torque converter transient characteristics prediction using computational fluid dynamics

    International Nuclear Information System (INIS)

    Yamaguchi, T; Tanaka, K

    2012-01-01

    The objective of this research is to investigate the transient torque converter performance used in an automobile. A new technique in computational fluid dynamics is introduced, which includes the inertia of the turbine in a three dimensional simulation of the torque converter during a launch condition. The simulation results are compared to experimental test data with good agreement across the range of data. In addition, the simulated flow structure inside the torque converter is visualized and compared to results from a steady-state calculation.

  2. Real-time full-field characterization of transient dissipative soliton dynamics in a mode-locked laser

    Science.gov (United States)

    Ryczkowski, P.; Närhi, M.; Billet, C.; Merolla, J.-M.; Genty, G.; Dudley, J. M.

    2018-04-01

    Dissipative solitons are remarkably localized states of a physical system that arise from the dynamical balance between nonlinearity, dispersion and environmental energy exchange. They are the most universal form of soliton that can exist, and are seen in far-from-equilibrium systems in many fields, including chemistry, biology and physics. There has been particular interest in studying their properties in mode-locked lasers, but experiments have been limited by the inability to track the dynamical soliton evolution in real time. Here, we use simultaneous dispersive Fourier transform and time-lens measurements to completely characterize the spectral and temporal evolution of ultrashort dissipative solitons as their dynamics pass through a transient unstable regime with complex break-up and collisions before stabilization. Further insight is obtained from reconstruction of the soliton amplitude and phase and calculation of the corresponding complex-valued eigenvalue spectrum. These findings show how real-time measurements provide new insights into ultrafast transient dynamics in optics.

  3. Features wear nodes mechanization wing aircraft operating under dynamic loads

    Directory of Open Access Journals (Sweden)

    А.М. Хімко

    2009-03-01

    Full Text Available  The conducted researches of titanic alloy ВТ-22 at dynamic loading with cycled sliding and dynamic loading in conditions of rolling with slipping. It is established that roller jamming in the carriage increases wear of rod of mechanization of a wing to twenty times. The optimum covering for strengthening wearied sites and restoration of working surfaces of wing’s mechanization rod is defined.

  4. Transient behaviour of small HTR for cogeneration

    International Nuclear Information System (INIS)

    Verkerk, E.C.; Van Heek, A.I.

    2000-01-01

    The Dutch market for combined generation of heat and power identifies a unit size of 40 MW thermal for the conceptual design of a nuclear cogeneration plant. The ACACIA system provides 14 MWe electricity combined with 17 t/h of high temperature steam (220 deg C, 10 bar) with a pebble-bed high temperature reactor directly coupled with a helium compressor and a helium turbine. The design of this small CHP unit that is used for industrial applications is mainly based on a pre-feasibility study in 1996, performed by a joint working group of five Dutch organisations, in which technical feasibility was shown. Thermal hydraulic and reactor physics analyses show favourable control characteristics during normal operation and a benign response to loss of helium coolant and loss of flow conditions. Throughout the response on these highly infrequent conditions, ample margin exists between the highest fuel temperatures and the temperature above which fuel degradation will occur. To come to quantitative statements about the ACACIA transient behaviour, a calculational coupling between the high temperature reactor core analysis code package PANTHER/DIREKT and the thermal hydraulic code RELAP5 for the energy conversion system has been made. This coupling offers a more realistic simulation of the entire system, since it removes the necessity of forcing boundary conditions on the simulation models at the data transfer points. In this paper, the models used for the dynamic components of the energy conversion system are described, and the results of the calculation for two operational transients in order to demonstrate the effects of the interaction between reactor core and its energy conversion system are shown. Several transient cases that are representative as operational transients for an HTR will be discussed, including one representing a load rejection case that shows the functioning of the control system, in particular the bypass valve. Another transient is a load following

  5. Simulation of Structures Exhibiting Instability Under Thermal-Mechanical Transient Loading

    Science.gov (United States)

    2015-08-25

    stiffness of the system becomes singular when the structure loses stability. The tangent stiffness matrix of the system can be obtained from Eqs. (7) and...L. Virgin , Vibration of axially loaded structures, Cambridge University Press, 2007. [4] A. Przekoo and S. A. Rizzi, Dynamic snap-through of thin...walled structures by a reduced-order model, AIAA Journal, 45 (10) (2007) 2510-2519. [5] Y. Chandra, I. Stanciulescu, L. N. Virgin , T. G. Eason, and S. M

  6. A STUDY ON DYNAMIC LOAD HISTORY RECONSTRUCTION USING PSEUDO-INVERSE METHODS

    OpenAIRE

    Santos, Ariane Rebelato Silva dos; Marczak, Rogério José

    2017-01-01

    Considering that the vibratory forces generally cannot be measured directly at the interface of two bodies, an inverse method is studied in the present work to recover the load history in such cases. The proposed technique attempts to reconstruct the dynamic loads history by using a frequency domain analysis and Moore-Penrose pseudo-inverses of the frequency response function (FRF) of the system. The methodology consists in applying discrete dynamic loads on a finite element model in the time...

  7. Dynamic preventive control of electric power systems through load shedding; Controle preventivo dinamico de sistemas de energia eletrica: formulacao atraves do corte de carga

    Energy Technology Data Exchange (ETDEWEB)

    Righeto, Luzia F.P.; Minussi, Carlos R. [UNESP, Ilha Solteira, SP (Brazil). Dept. de Engenharia Eletrica

    1997-12-31

    This work presents a model to be used in Electric Power System preventive control, taking into account the dynamic network aspects, the effects caused by great oscillations in the synchronous machines angles (transient stability), electric equipment outages, short-circuit, etc. The energy function will be used as a form of measure the system stability degree using a criterion defined as security margin. The used control action will be the load shedding. (author) 16 refs.; e-mail: minussi at dee.feis.unesp.br

  8. Simplified distributed parameters BWR dynamic model for transient and stability analysis

    International Nuclear Information System (INIS)

    Espinosa-Paredes, Gilberto; Nunez-Carrera, Alejandro; Vazquez-Rodriguez, Alejandro

    2006-01-01

    This paper describes a simplified model to perform transient and linear stability analysis for a typical boiling water reactor (BWR). The simplified transient model was based in lumped and distributed parameters approximations, which includes vessel dome and the downcomer, recirculation loops, neutron process, fuel pin temperature distribution, lower and upper plenums reactor core and pressure and level controls. The stability was determined by studying the linearized versions of the equations representing the BWR system in the frequency domain. Numerical examples are used to illustrate the wide application of the simplified BWR model. We concluded that this simplified model describes properly the dynamic of a BWR and can be used for safety analysis or as a first approach in the design of an advanced BWR

  9. A Dynamic Model for Load Balancing in Cloud Infrastructure

    Directory of Open Access Journals (Sweden)

    Jitendra Bhagwandas Bhatia

    2015-08-01

    Full Text Available This paper analysis various challenges faced in optimizing computing resource utilization via load balancing and presents a platform-independent model for load balancing which targets high availability of resources, low SLA (Service Level agreement violations and saves power. To achieve this, incoming requests are monitored for sudden burst, a prediction model is employed to maintain high availability and a power-aware algorithm is applied for choosing a suitable physical node for a virtual host. The proposed dynamic load balancing model provides a way to conflicting goals of saving power and maintaining high resource availability.For anyone building a private, public or hybrid IaaS cloud infrastructure, load balancing of virtual hosts on a limited number of physical nodes, becomes a crucial aspect. This paper analysis various challenges faced in optimizing computing resource utilization via load balancing and presents a platform independent model for load balancing which targets high availability of resources, low SLA (Service Level agreement violations and saves power. To achieve this, incoming requests are monitored for sudden burst, prediction model is employed to maintain high availability and power aware algorithm is applied for choosing a suitable physical node for virtual host. The proposed dynamic load balancing model provides a way to conflicting goals of saving power and maintaining high resource availability.

  10. In-situ imaging of tungsten surface modification under ITER-like transient heat loads

    Directory of Open Access Journals (Sweden)

    A.A. Vasilyev

    2017-08-01

    Full Text Available Experimental research on behavior of rolled tungsten plates under intense transient heat loads generated by a powerful (a total power of up to 7 MW long-pulse (0.1–0.3ms electron beam with full irradiation area of 2 cm2 was carried out. Imaging of the sample by the fast CCD cameras in the NIR range and with illumination by the 532nm continuous-wave laser was applied for in-situ surface diagnostics during exposure. In these experiments tungsten plates were exposed to heat loads 0.5–1MJ/m2 with a heat flux factor (Fhf close to and above the melting threshold of tungsten at initial room temperature. Crack formation and crack propagation under the surface layer were observed during multiple exposures. Overheated areas with excessive temperature over surrounding surface of about 500K were found on severely damaged samples more than 5ms after beam ending. The application of laser illumination enables to detect areas of intense tungsten melting near crack edges and crack intersections.

  11. Loading dynamics of a sliding DNA clamp.

    KAUST Repository

    Cho, Won-Ki; Jergic, Slobodan; Kim, Daehyung; Dixon, Nicholas E; Lee, Jong-Bong

    2014-01-01

    8° during clamp closure. The single-molecule polarization and FRET studies thus revealed the real-time dynamics of the ATP-hydrolysis-dependent 3D conformational change of the β clamp during loading at a ss/dsDNA junction.

  12. Dynamic Feedforward Control of a Diesel Engine Based on Optimal Transient Compensation Maps

    Directory of Open Access Journals (Sweden)

    Giorgio Mancini

    2014-08-01

    Full Text Available To satisfy the increasingly stringent emission regulations and a demand for an ever lower fuel consumption, diesel engines have become complex systems with many interacting actuators. As a consequence, these requirements are pushing control and calibration to their limits. The calibration procedure nowadays is still based mainly on engineering experience, which results in a highly iterative process to derive a complete engine calibration. Moreover, automatic tools are available only for stationary operation, to obtain control maps that are optimal with respect to some predefined objective function. Therefore, the exploitation of any leftover potential during transient operation is crucial. This paper proposes an approach to derive a transient feedforward (FF control system in an automated way. It relies on optimal control theory to solve a dynamic optimization problem for fast transients. A partially physics-based model is thereby used to replace the engine. From the optimal solutions, the relevant information is extracted and stored in maps spanned by the engine speed and the torque gradient. These maps complement the static control maps by accounting for the dynamic behavior of the engine. The procedure is implemented on a real engine and experimental results are presented along with the development of the methodology.

  13. Runaway transient simulation of a model Kaplan turbine

    Energy Technology Data Exchange (ETDEWEB)

    Liu, S; Liu, D; Wu, Y [State Key Laboratory of Hydroscience and Engineering, Department of Thermal Eng., Tsinghua University, Beijing, 100084 (China); Zhou, D [Water Conservancy and Hydropower Eng., Hohai University, Nanjing. 210098 (China); Nishi, M, E-mail: liushuhong@tsinghua.edu.c [Kyushu Inst. Tech. Senior Academy, Kitakyushu, 804-8550 (Japan)

    2010-08-15

    The runaway transient is a typical transient process of a hydro power unit, where the rotational speed of a turbine runner rapidly increases up to the runaway speed under a working head as the guide vanes cannot be closed due to some reason at the load rejection. In the present paper, the characteristics of the runaway transient of a model Kaplan turbine having ns = 479(m-kW) is simulated by using a time-dependent CFD technique where equation of rotational motion of runner, continuity equation and unsteady RANS equations with RNG k-{epsilon} turbulence model are solved iteratively. In the calculation, unstructured mesh is used to the whole flow passage, which consists of several sub-domains: entrance, casing, stay vanes + guide vanes, guide section, runner and draft tube. And variable speed sliding mesh technique is used to exchange interface flow information between moving part and stationary part, and three-dimensional unstructured dynamic mesh technique is also adopted to ensure mesh quality. Two cases were treated in the simulation of runaway transient characteristics after load rejection: one is the rated operating condition as the initial condition, and the other is the condition at the maximum head. Regarding the runaway speed, the experimental speed is 1.45 times the initial speed and the calculation is 1.47 times the initial for the former case. In the latter case, the experiment and the calculation are 1.67 times and 1.69 times respectively. From these results, it is recognized that satisfactorily prediction will be possible by using the present numerical method. Further, numerical results show that the swirl in the draft-tube flow becomes stronger in the latter part of the transient process so that a vortex rope will occur in the draft tube and its precession will cause the pressure fluctuations which sometimes affect the stability of hydro power system considerably.

  14. Runaway transient simulation of a model Kaplan turbine

    Science.gov (United States)

    Liu, S.; Zhou, D.; Liu, D.; Wu, Y.; Nishi, M.

    2010-08-01

    The runaway transient is a typical transient process of a hydro power unit, where the rotational speed of a turbine runner rapidly increases up to the runaway speed under a working head as the guide vanes cannot be closed due to some reason at the load rejection. In the present paper, the characteristics of the runaway transient of a model Kaplan turbine having ns = 479(m-kW) is simulated by using a time-dependent CFD technique where equation of rotational motion of runner, continuity equation and unsteady RANS equations with RNG k-epsilon turbulence model are solved iteratively. In the calculation, unstructured mesh is used to the whole flow passage, which consists of several sub-domains: entrance, casing, stay vanes + guide vanes, guide section, runner and draft tube. And variable speed sliding mesh technique is used to exchange interface flow information between moving part and stationary part, and three-dimensional unstructured dynamic mesh technique is also adopted to ensure mesh quality. Two cases were treated in the simulation of runaway transient characteristics after load rejection: one is the rated operating condition as the initial condition, and the other is the condition at the maximum head. Regarding the runaway speed, the experimental speed is 1.45 times the initial speed and the calculation is 1.47 times the initial for the former case. In the latter case, the experiment and the calculation are 1.67 times and 1.69 times respectively. From these results, it is recognized that satisfactorily prediction will be possible by using the present numerical method. Further, numerical results show that the swirl in the draft-tube flow becomes stronger in the latter part of the transient process so that a vortex rope will occur in the draft tube and its precession will cause the pressure fluctuations which sometimes affect the stability of hydro power system considerably.

  15. Runaway transient simulation of a model Kaplan turbine

    International Nuclear Information System (INIS)

    Liu, S; Liu, D; Wu, Y; Zhou, D; Nishi, M

    2010-01-01

    The runaway transient is a typical transient process of a hydro power unit, where the rotational speed of a turbine runner rapidly increases up to the runaway speed under a working head as the guide vanes cannot be closed due to some reason at the load rejection. In the present paper, the characteristics of the runaway transient of a model Kaplan turbine having ns = 479(m-kW) is simulated by using a time-dependent CFD technique where equation of rotational motion of runner, continuity equation and unsteady RANS equations with RNG k-ε turbulence model are solved iteratively. In the calculation, unstructured mesh is used to the whole flow passage, which consists of several sub-domains: entrance, casing, stay vanes + guide vanes, guide section, runner and draft tube. And variable speed sliding mesh technique is used to exchange interface flow information between moving part and stationary part, and three-dimensional unstructured dynamic mesh technique is also adopted to ensure mesh quality. Two cases were treated in the simulation of runaway transient characteristics after load rejection: one is the rated operating condition as the initial condition, and the other is the condition at the maximum head. Regarding the runaway speed, the experimental speed is 1.45 times the initial speed and the calculation is 1.47 times the initial for the former case. In the latter case, the experiment and the calculation are 1.67 times and 1.69 times respectively. From these results, it is recognized that satisfactorily prediction will be possible by using the present numerical method. Further, numerical results show that the swirl in the draft-tube flow becomes stronger in the latter part of the transient process so that a vortex rope will occur in the draft tube and its precession will cause the pressure fluctuations which sometimes affect the stability of hydro power system considerably.

  16. 78 FR 67323 - Special Conditions: Airbus, Model A350-900 Series Airplane; Transient Engine Failure Loads

    Science.gov (United States)

    2013-11-12

    ... feature. These proposed special conditions contain the additional safety standards that the Administrator... these conditions would be considered as ultimate loads, with an additional safety factor applied to the... ARAC Loads and Dynamics Harmonization Working Group. The proposed special condition reflects the ARAC...

  17. Dynamic changes in glucose metabolism of living rat brain slices induced by hypoxia and neurotoxic chemical-loading revealed by positron autoradiography

    International Nuclear Information System (INIS)

    Omata, N.; Fujibayashi, Y.; Waki, A.; Sadato, N.; Yano, R.; Yoshimoto, M.; Yonekura, Y.; Murata, T.; Yoshida, S.

    1999-01-01

    Fresh rat brain slices were incubated with 2-deoxy-2-[ 18 F]-fluoro-D-glucose ([ 18 F]FDG) in oxygenated Krebs-Ringer solution at 36 degree C, and serial two-dimensional time-resolved images of [ 18 F]FDG uptake were obtained from these specimens on imaging plates. The fractional rate constant (= k3*) of [ 18 F]FDG proportional to the cerebral glucose metabolic rate (CMRglc) was evaluated by applying the Gjedde-Patlak graphical method to the image data. With hypoxia loading (oxygen deprivation) or glucose metabolism inhibitors acting on oxidative phosphorylation, the k3* value increased dramatically suggesting enhanced glycolysis. After relieving hypoxia ≤10-min, the k3* value returned to the pre-loading level. In contrast, with ≥20-min hypoxia only partial or no recovery was observed, indicating that irreversible neuronal damage had been induced. However, after loading with tetrodotoxin (TTX), the k3* value also decreased but returned to the pre-loading level even after 70-min TTX-loading, reflecting a transient inhibition of neuronal activity. This technique provides a new means of quantifying dynamic changes in the regional CMRglc in living brain slices in response to various interventions such as hypoxia and neurotoxic chemical-loading as well as determining the viability and prognosis of brain tissues. (author)

  18. Excited state dynamics of beta-carotene explored with dispersed multi-pulse transient absorption

    NARCIS (Netherlands)

    Larsen, D.S.; Papagiannakis, E.; van Stokkum, I.H.M.; Vengris, M.; Kennis, J.T.M.; van Grondelle, R.

    2003-01-01

    The excited-state dynamics of β-carotene in hexane was studied with dispersed ultrafast transient absorption techniques. A new excited state is produced after blue-edge excitation. Pump-repump-probe and pump-dump-probe measurements identified and characterized this state, termed S‡, which exhibits a

  19. Investigation of control system of traction electric drive with feedbacks on load

    Science.gov (United States)

    Kuznetsov, N. K.; Iov, I. A.; Iov, A. A.

    2018-03-01

    In the article, by the example of a walking excavator, the results of a study of a control system of traction electric drive with a rigid and flexible feedback on the load are mentioned. Based on the analysis of known works, the calculation scheme has been chosen; the equations of motion of the electromechanical system have been obtained, taking into account the elasticity of the rope and feedbacks on the load in the elastic element. A simulation model of this system has been developed and mathematical modeling of the transient processes to evaluate the influence of feedback on the dynamic characteristics of the mechanism and its efficiency of work was carried out. It is shown that the use of rigid and flexible feedbacks makes it possible to reduce dynamic loads in the traction mechanism and to limit the elastic oscillation of the executive mechanism in transient operating modes in comparison with the standard control system; however, there is some decrease in productivity. It has been also established that the sign-variable of the loading of the electric drive, connected with the opening of the backlashes in the gearbox due to the action of feedbacks on the load in the elastic element, under certain conditions, can lead to undesirable phenomena in the operation of the drive and a decrease in the reliability of its operation.

  20. Effects of moving dynamic tyre loads on tyre-pavement contact stresses

    CSIR Research Space (South Africa)

    Steyn, WJvdM

    2002-01-01

    Full Text Available The purpose of this paper is to indicate the effect that moving dynamic tyre loads has on the tyre-pavement contact stresses used in pavement analysis. Traditionally tyre loads (in pavement analysis) are modelled as constant loads applied through...

  1. Numerical investigation of transient beam loading compensation in JLC X-band main linac

    International Nuclear Information System (INIS)

    Syrachev, I.V.; Higo, T.

    1996-06-01

    In the present paper, two methods, 'staggered timing' and 'RF modulation', were studied for the transient beam loading compensation in the JLC X-band main linac. The inter bunch energy spread was found to be easily reduced down to less than ±0.06% with 10 sets of injection timings along the linac in the former case while with a simple linear ramping of the input RF voltage in the latter case. For both cases the energy transfer efficiencies from the power source to the beam were exactly the same. The tolerance of the beam intensity jitter was found to be ±1% for the multibunch energy spread of ±0.1%. (author)

  2. DYNAMIC TIME HISTORY ANALYSIS OF BLAST RESISTANT DOOR USING BLAST LOAD MODELED AS IMPACT LOAD

    Directory of Open Access Journals (Sweden)

    Y. A. Pranata

    2012-06-01

    Full Text Available A blast resistant single door was designed to withstand a 0.91 bar blast pressure and 44 ms blast duration. The analysis was done using Dynamic Time History Analysis using Blast Load modeled as Impact Load for given duration. The material properties used have been modified to accommodate dynamic effects. The analysis was done using dynamic finite element method (fem for time of the blast duration, and the maximum/minimum internal forces and displacement were taken from the time history output, in order to know the behavior under blast load and estimate the safety margin of the door. Results obtained from this research indicated that the maximum z-displacement is 1.709 mm, while in the term of serviceability, the permitted is 25 mm. The maximum reaction force is 73,960 N, while the maximum anchor capacity is 82,069 N. On blast condition, the maximum frame stress is 71.71 MPa, the maximum hinge shear stress is 45.28 MPa. While on rebound condition, the maximum frame stress is 172.11 MPa, the maximum hinge shear stress is 29.46 MPa. The maximum door edge rotation is 0.44 degree, which is not exceed the permitted boundary (1.2 degree. Keywords: Dynamic time history, blast resistant door, single door, finite element method.

  3. Curing dynamics of photopolymers measured by single-shot heterodyne transient grating method.

    Science.gov (United States)

    Arai, Mika; Fujii, Tomomi; Inoue, Hayato; Kuwahara, Shota; Katayama, Kenji

    2013-01-01

    The heterodyne transient grating (HD-TG) method was first applied to the curing dynamics measurement of photopolymers. The curing dynamics for various monomers including an initiator (2.5 vol%) was monitored optically via the refractive index change after a single UV pulse irradiation. We could obtain the polymerization time and the final change in the refractive index, and the parameters were correlated with the viscosity, molecular structure, and reaction sites. As the polymerization time was longer, the final refractive change was larger, and the polymerization time was explained in terms of the monomer properties.

  4. Dynamic transient analysis of rupture disks by the finite-element method

    International Nuclear Information System (INIS)

    Hsieh, B.J.

    1975-02-01

    A finite element method utilizing the principle of virtual work in convected coordinates is used to analyze the axisymmetric dynamic transient response of rupture disks. This method can treat non-linearities arising both from inelastic material properties and large displacements/rotations provided that the convected strains are small. This report contains extensive calculations using a variety of rupture disk geometries and attempts to relate the static buckling of such disks to their dynamic response characteristics. A majority of the calculations treat the response of 18 inch disks typical of those currently considered for use in the Clinch River Breeder Reactor intermediate heat transport system

  5. Mechanical behavior of ultrafine-grained materials under combined static and dynamic loadings

    Directory of Open Access Journals (Sweden)

    Guo Y.Z.

    2015-01-01

    Full Text Available Ultrafine-grained (UFG materials have extensive prospects for engineering application due to their excellent mechanical properties. However, the grain size decrease reduces their strain hardening ability and makes UFG materials more susceptible to deformation instability such as shear localization. In most cases, critical shear strain is taken as the criterion for formation of shear localization under impact loading or adiabatic shear band (ASB. Recently, some researchers found that the formation of ASB was determined only by the dynamic loading process and had nothing to do with its static loading history. They proposed for coarse-grained metals a dynamic stored energy-based criterion for ASB and verified it by some experiments. In this study, we will focus on the shear localization behavior of UFG metals such as UFG titanium and magnesium alloy AZ31. Quasi-static loading and dynamic loading will be applied on the same specimen alternately. The shear localization behavior will be analyzed and the criterion of its formation will be evaluated.

  6. Erosion simulation of first wall beryllium armour after ITER transient heat loads and runaway electrons action

    Energy Technology Data Exchange (ETDEWEB)

    Bazylev, B., E-mail: boris.bazylev@kit.edu [Karlsruhe Institute of Technology, IHM, P.O. Box 3640, D-76021 Karlsruhe (Germany); Igitkhanov, Yu.; Landman, I.; Pestchanyi, S. [Karlsruhe Institute of Technology, IHM, P.O. Box 3640, D-76021 Karlsruhe (Germany); Loarte, A. [ITER Organisation, Cadarache, 13108 Saint Paul Lez Durance Cedex (France)

    2011-10-01

    Beryllium is foreseen as plasma facing armour for the first wall (FW) in ITER in form of Be-clad blanket modules in macrobrush design with brush size about 8-10 cm. In ITER significant heat loads during transient events (TE) and runaway electrons impact are expected at the main chamber wall that may leads to the essential damage of the Be armour. The main mechanisms of metallic target damage remain surface melting, evaporation, and melt motion, which determine the life-time of the plasma facing components. The melt motion damages of Be macrobrush armour caused by the tangential friction force and the J x B forces are analyzed for bulk Be and different sizes of Be-brushes. The damage of the FW due to heat loads caused by runaway electrons is numerically simulated.

  7. Erosion simulation of first wall beryllium armour after ITER transient heat loads and runaway electrons action

    International Nuclear Information System (INIS)

    Bazylev, B.; Igitkhanov, Yu.; Landman, I.; Pestchanyi, S.; Loarte, A.

    2011-01-01

    Beryllium is foreseen as plasma facing armour for the first wall (FW) in ITER in form of Be-clad blanket modules in macrobrush design with brush size about 8-10 cm. In ITER significant heat loads during transient events (TE) and runaway electrons impact are expected at the main chamber wall that may leads to the essential damage of the Be armour. The main mechanisms of metallic target damage remain surface melting, evaporation, and melt motion, which determine the life-time of the plasma facing components. The melt motion damages of Be macrobrush armour caused by the tangential friction force and the J x B forces are analyzed for bulk Be and different sizes of Be-brushes. The damage of the FW due to heat loads caused by runaway electrons is numerically simulated.

  8. Feasibility of Applying Controllable Lubrication to Dynamically Loaded Journal Bearings

    DEFF Research Database (Denmark)

    Estupinan, Edgar Alberto; Santos, Ilmar

    2009-01-01

    A multibody dynamic model of the main mechanical components of a hermetic reciprocating compressor is presented in this work. Considering that some of the mechanical elements are interconnected via thin fluid films, the multibody dynamic model is coupled to the equations from the dynamics...... of the fluid films, based on fluid film theory. For a dynamically loaded journal bearing, the fluid film pressure distribution can be computed by numerically solving the Reynolds equation, by means of finite-difference method. Particularly, in this study the main focus is on the lubrication behavior...... and reaction forces in a reciprocating compressor have a cyclic behavior, periodic oil pressure injection rules based on the instantaneous crank angle and load bearing condition can be established. In this paper, several bearing configurations working under different oil pressure injection rules conditions...

  9. Ultrafast dynamic ellipsometry and spectroscopies of laser shocked materials

    Energy Technology Data Exchange (ETDEWEB)

    Mcgrane, Shawn David [Los Alamos National Laboratory; Bolme, Cindy B [Los Alamos National Laboratory; Whitley, Von H [Los Alamos National Laboratory; Moore, David S [Los Alamos National Laboratory

    2010-01-01

    Ultrafast ellipsometry and transient absorption spectroscopies are used to measure material dynamics under extreme conditions of temperature, pressure, and volumetric compression induced by shock wave loading with a chirped, spectrally clipped shock drive pulse.

  10. Dynamic Loading of Carrara Marble in a Heated State

    Science.gov (United States)

    Wong, Louis Ngai Yuen; Li, Zhihuan; Kang, Hyeong Min; Teh, Cee Ing

    2017-06-01

    Useable land is a finite space, and with a growing global population, countries have been exploring the use of underground space as a strategic resource to sustain the growth of their society and economy. However, the effects of impact loading on rocks that have been heated, and hence the integrity of the underground structure, are still not fully understood and has not been included in current design standards. Such scenarios include traffic accidents and explosions during an underground fire. This study aims to provide a better understanding of the dynamic load capacity of Carrara marble at elevated temperatures. Dynamic uniaxial compression tests are performed on Carrara marble held at various temperatures using a split-Hopkinson Pressure Bar (SHPB) setup with varying input force. A customized oven is included in the SHPB setup to allow for testing of the marble specimens in a heated state. After the loading test, a three-wave analysis is performed to obtain the dynamic stress-strain curve of the specimen under loading. The fragments of the failed specimens were also collected and dry-sieved to obtain the particle size distribution. The results reveal that the peak stress of specimens that have been heated is negatively correlated with the heating temperature. However, the energy absorbed by the specimens at peak stress at all temperatures is similar, indicating that a significant amount of energy is dissipated via plastic deformation. Generally, fragment size is also found to show a negative correlation with heating temperature and loading pressure. However, in some cases this relationship does not hold true, probably due to the occurrence of stress shadowing. Linear Elastic Fracture Mechanics has been found to be generally applicable to specimens tested at low temperatures; but at higher temperatures, Elastic-Plastic Fracture Mechanics will give a more accurate prediction. Another contribution of this study is to show that other than the peak stress of the

  11. Coupled problems in transient fluid and structural dynamics in nuclear engineering

    International Nuclear Information System (INIS)

    Krieg, R.

    1978-01-01

    Some important problems in coupled fluid-structural dynamics which occur in safety investigations of liquid metal fast breeder reactors (LMFBR). light water reactors and nuclear reprocessing plants are discussed and a classification of solution methods is introduced. A distinction is made between the step by step solution procedure, where available computer codes in fluid and structural dynamics are coupled, and advanced simultaneous solution methods, where the coupling is carried out at the level of the fundamental equations. Results presented include the transient deformation of a two-row pin bundle surrounded by an infinite fluid field, vapour explosions in a fluid container and containment distortions due to bubble collapse in the pressure suppression system of a boiling water reactor. A recently developed simultaneous solution method is presented in detail. Here the fluid dynamics (inviscid, incompressible fluid) is described by a singularity method which reduces the three-dimensional fluid dynamics problems to a two-dimensional formulation. In this way the three-dynamics fluid dynamics as well as the structural (shell) dynamics can be described essentially by common unknowns at the fluid-structural interface. The resulting equations for the coupled fluid-structural dynamics are analogous to to the equations of motion of the structural dynamics alone. (author)

  12. Assessments of the kinetic and dynamic transient behavior of sub-critical systems (ADS) in comparison to critical reactor systems

    International Nuclear Information System (INIS)

    Schikorr, W.M.

    2001-01-01

    The neutron kinetic and the reactor dynamic behavior of Accelerator Driven Systems (ADS) is significantly different from those of conventional power reactor systems currently in use for the production of power. It is the objective of this study to examine and to demonstrate the intrinsic differences of the kinetic and dynamic behavior of accelerator driven systems to typical plant transient initiators in comparison to the known, kinetic and dynamic behavior of critical thermal and fast reactor systems. It will be shown that in sub-critical assemblies, changes in reactivity or in the external neutron source strength lead to an asymptotic power level essentially described by the instantaneous power change (i.e. prompt jump). Shutdown of ADS operating at high levels of sub-criticality, (i.e. k eff ∼0.99), without the support of reactivity control systems (such as control or safety rods), may be problematic in case the ability of cooling of the core should be impaired (i.e. loss of coolant flow). In addition, the dynamic behavior of sub-critical systems to typical plant transients such as protected or unprotected loss of flow (LOF) or heat sink (LOH) transients are not necessarily substantially different from the plant dynamic behavior of critical systems if the reactivity feedback coefficients of the ADS design are unfavorable. As expected, the state of sub-criticality and the temperature feedback coefficients, such as Doppler and coolant temperature coefficient, play dominant roles in determining the course and direction of plant transients. Should the combination of these safety coefficients be very unfavorable, not much additional margin in safety may be gained by making a critical system only sub-critical (i.e. k eff ∼0.95). A careful optimization procedure between the selected operating level of sub-criticality, the safety reactivity coefficients and the possible need for additional reactivity control systems seems, therefore, advisable during the early

  13. Dynamic Response and Failure Mechanism of Brittle Rocks Under Combined Compression-Shear Loading Experiments

    Science.gov (United States)

    Xu, Yuan; Dai, Feng

    2018-03-01

    A novel method is developed for characterizing the mechanical response and failure mechanism of brittle rocks under dynamic compression-shear loading: an inclined cylinder specimen using a modified split Hopkinson pressure bar (SHPB) system. With the specimen axis inclining to the loading direction of SHPB, a shear component can be introduced into the specimen. Both static and dynamic experiments are conducted on sandstone specimens. Given carefully pulse shaping, the dynamic equilibrium of the inclined specimens can be satisfied, and thus the quasi-static data reduction is employed. The normal and shear stress-strain relationships of specimens are subsequently established. The progressive failure process of the specimen illustrated via high-speed photographs manifests a mixed failure mode accommodating both the shear-dominated failure and the localized tensile damage. The elastic and shear moduli exhibit certain loading-path dependence under quasi-static loading but loading-path insensitivity under high loading rates. Loading rate dependence is evidently demonstrated through the failure characteristics involving fragmentation, compression and shear strength and failure surfaces based on Drucker-Prager criterion. Our proposed method is convenient and reliable to study the dynamic response and failure mechanism of rocks under combined compression-shear loading.

  14. Dynamic Load Balancing for PIC code using Eulerian/Lagrangian partitioning

    OpenAIRE

    Sauget, Marc; Latu, Guillaume

    2017-01-01

    This document presents an analysis of different load balance strategies for a Plasma physics code that models high energy particle beams with PIC method. A comparison of different load balancing algorithms is given: static or dynamic ones. Lagrangian and Eulerian partitioning techniques have been investigated.

  15. Digitally Controlled Point of Load Converter with Very Fast Transient Response

    DEFF Research Database (Denmark)

    Jakobsen, Lars Tønnes; Andersen, Michael Andreas E.

    2007-01-01

    voltage mode control and very fast transient response. The DiSOM modulator is combined with a digital PID compensator algorithm is implemented in a hybrid CPLD/FPGA and is used to control a synchronous Buck converter, which is used in typical Point of Load applications. The computational time is only......This paper presents a new Digital Self-Oscillating Modulator (DiSOM) that allows the duty cycle to be changed instantly. The DiSOM modulator is shown to have variable switching that is a function of the duty cycle. Compared to a more traditional digital PWM modulator based on a counter...... and comparator the DiSOM modulator allows the sampling frequency of the output voltage control loop to be higher than the switching frequency of the power converter, typically a DC/DC converter. The features of the DiSOM modulator makes it possible to design a digitally controlled DC/DC converter with linear...

  16. Effects of transient conditions on exhaust emissions from two non-road diesel engines

    International Nuclear Information System (INIS)

    Lindgren, M.; Hansson, P.-A.

    2004-01-01

    Growing interest in quantifying and reducing the amount of engine emissions of carbon monoxide, hydrocarbons, and nitrogen oxides loading the environment has led to increasingly tighter environmental regulations. However, current non-road emission standards are performed according to a steady-state test cycle, which does not include transient effects and thus underestimates the amount of emissions produced in real use of the engine. This study quantifies the effects of transients in engine speed and torque on the fuel consumption and emissions from two diesel engines intended for non-road mobile machinery. Fuel consumption and emissions from the engines were measured in an engine dynamometer during various transient load conditions. The results showed that during fast transients, the measured fuel consumption was up to twice as high as the corresponding steady-state load conditions. The effects of transients on emissions of nitrogen oxides were even greater, as were the effects of transient load increase with increasing transient conditions i. e. rate of change. The results showed that the effect of transients on fuel consumption and emissions were also dependent on the type of diesel injection pump and the engine equipment used. Furthermore, the results indicated that the air/fuel ratio was an important contributor to the emission formation process during transient loads. (Author)

  17. Calculation of vessels and heat exchangers submitted to dynamic efforts caused by postulated ruptures in pipeline

    International Nuclear Information System (INIS)

    Ferrari, L.D.B.; Amaral, J.A.R. do; Alves, M.C.T.

    1984-01-01

    An example of dynamic analysis of a heat exchanger subjected to pipe break transient loadings is shown. The contribution of the type of loading and component's model is discussed. Simplified verification methods are also presented. (Author) [pt

  18. Assessment of remedial control schemes for damping transient oscillations in the Mexican system

    Energy Technology Data Exchange (ETDEWEB)

    Castellanos, R.B.; Sarmiento, H.U.; Pampin, G. [Inst.de Investigaciones Electricas, Morelos (Mexico); Messina, A.R. [Cinvestav, San Pedro Zacatenco (Mexico)

    2008-07-01

    In order to enhance voltage control and power system dynamic performance, special protection systems (SPS) are increasingly being used in the Mexican Interconnected System (MIS). These include extensive use of direct load shedding schemes, generator tripping schemes, controlled disconnection of lines, and automatic generation rejection and single phase reclosing schemes. Generator tripping based on local detection of severe disturbance is of particular importance and has been used to enhance transient stability. In addition, the onset of system instability has become more complex, often involving interactions between major system modes. Post-fault transient oscillations have become more common following the loss of major system elements and may result in uncontrolled system separation. This has motivated the need to develop system-wide special protection systems. This paper explored the possible benefits and feasibility of employing SPSs to mitigate wide-area inter-area oscillations in the MIS. The paper described the exploratory studies such as the coordinated application of automatic generation tripping schemes and automatic load shedding to enhance system dynamic performance. The paper also explained sensitivity studies that were conducted to determine the amount and location of generation (load) to be shed and suggested extensions to the basic security criteria to maintain network stability. The proposed techniques were developed and tested on a large-scale representation of the Mexican system that included the operation of several FACTS controllers. It was concluded that automatic generation shedding and automatic loading shedding were efficient alternatives to improve generation and transmission use, reliability and flexibility. 7 refs., 1 tab., 3 figs.

  19. The Effect of the Loading on Dynamic Stability and Scapular Asymmetry

    Directory of Open Access Journals (Sweden)

    Mohammad Hassan Azarsa

    2014-03-01

    Full Text Available Background: Scapular stabilization and neuromuscular control provide an important parameter to characterize shoulder function during dynamic activities. Many studies have confirmed the effect of the loading on scapular position and scapulohumeral rhythm. Therefore, the evaluation of stabilizer muscles involvement in scapular asymmetry may assist in the development of clinical examination and rehabilitation program. The aim of this study was to evaluate the effect of loading on dynamic stability and scapular asymmetry in basketball players. Methods: Thirty healthy male basketball players aged between 20 to 31 years old were tested. The linear distance between scapular inferior angle and T7 spinous process was measured using a caliper in 90 degrees of unloaded scaption and with 1, 2 and 4 kg loading. The difference of distances of two sides in the above 4 positions was analyzed. Results: The amount of distances difference in two sides with 1 kg loading was minimal (9.36 mm. This difference increased to 10.19 mm and 12.22 mm, with increasing the loading to 2 and 4 kg respectively; although the 4 positions of the test did not show significant differences in distances difference (P>0.05. Conclusion: This study shows that dynamic stability of the scapula is dependent on the role of muscles, so that with increasing load on the muscles, the scapular asymmetry is more pronounced.

  20. Using Gait Dynamics to Estimate Load from a Body-Worn Accelerometer

    Science.gov (United States)

    2016-02-05

    dynamics, ambulation, correlation structure, musculoskeletal injury I. INTRODUCTION ilitary personnel commonly engage in training and operational...according to their load estimation accuracy, which is defined by the Pearson correlation , r, of its load estimates with the true loads (see Tables...method. In Table IV are shown the mean absolute error, MAE, and Pearson correlation , r, of the load estimates using estimates from GS alone, PLS alone

  1. Real-Time Monitoring of Low-Level Mixed-Waste Loading during Polyethylene Microencapsulation using Transient Infrared Spectroscopy

    International Nuclear Information System (INIS)

    Jones, Roger W.; Kalb, Paul D.; McClelland, John F.; Ochiai, Shukichi

    1999-01-01

    In polyethylene microencapsulation, low-level mixed waste (LLMW) is homogenized with molten polyethylene and extruded into containers, resulting in a lighter, lower-volume waste form than cementation and grout methods produce. Additionally, the polyethylene-based waste form solidifies by cooling, with no risk of the waste interfering with cure, as may occur with cementation and grout processes. We have demonstrated real-time monitoring of the polyethylene encapsulation process stream using a noncontact device based on transient infrared spectroscopy (TIRS). TIRS can acquire mid-infrared spectra from solid or viscous liquid process streams, such as the molten, waste-loaded polyethylene stream that exits the microencapsulation extruder. The waste loading in the stream was determined from the TIRS spectra using partial least squares techniques. The monitor has been demonstrated during the polyethylene microencapsulation of nitrate-salt LLMW and its surrogate, molten salt oxidation LLMW and its surrogate, and flyash. The monitor typically achieved a standard error of prediction for the waste loading of about 1% by weight with an analysis time under 1 minute

  2. Dynamic analysis of a pumped-storage hydropower plant with random power load

    Science.gov (United States)

    Zhang, Hao; Chen, Diyi; Xu, Beibei; Patelli, Edoardo; Tolo, Silvia

    2018-02-01

    This paper analyzes the dynamic response of a pumped-storage hydropower plant in generating mode. Considering the elastic water column effects in the penstock, a linearized reduced order dynamic model of the pumped-storage hydropower plant is used in this paper. As the power load is always random, a set of random generator electric power output is introduced to research the dynamic behaviors of the pumped-storage hydropower plant. Then, the influences of the PI gains on the dynamic characteristics of the pumped-storage hydropower plant with the random power load are analyzed. In addition, the effects of initial power load and PI parameters on the stability of the pumped-storage hydropower plant are studied in depth. All of the above results will provide theoretical guidance for the study and analysis of the pumped-storage hydropower plant.

  3. An Optimal PR Control Strategy with Load Current Observer for a Three-Phase Voltage Source Inverter

    Directory of Open Access Journals (Sweden)

    Xiaobo Dou

    2015-07-01

    Full Text Available Inverter voltage control is an important task in the operation of a DC/AC microgrid system. To improve the inverter voltage control dynamics, traditional approaches attempt to measure and feedforward the load current, which, however, needs remote measurement with communications in a microgrid system with distributed loads. In this paper, a load current observer (LCO based control strategy, which does not need remote measurement, is proposed for sinusoidal signals tracking control of a three-phase inverter of the microgrid. With LCO, the load current is estimated precisely, acting as the feedforward of the dual-loop control, which can effectively enlarge the stability margin of the control system and improve the dynamic response to load disturbance. Furthermore, multiple PR regulators are applied in this strategy conducted in a stationary  frame to suppress the transient fluctuations and the total harmonic distortion (THD of the output voltage and achieve faster transient performance compared with traditional dual-loop control in a rotating dq0 frame under instantaneous change of various types of load (i.e., balanced load, unbalanced load, and nonlinear load. The parameters of multiple PR regulators are analyzed and selected through the root locus method and the stability of the whole control system is evaluated and analyzed. Finally, the validity of the proposed approach is verified through simulations and a three-phase prototype test system with a TMS320F28335 DSP.

  4. Loading Processes Dynamics Modelling Taking into Account the Bucket-Soil Interaction

    Directory of Open Access Journals (Sweden)

    Carmen Debeleac

    2007-10-01

    Full Text Available The author propose three dynamic models specialized for the vibrations and resistive forces analysis that appear at the loading process with different construction equipment like frontal loaders and excavators.The models used putting into evidence the components of digging: penetration, cutting, and loading.The conclusions of this study consist by evidentiate the dynamic overloads that appear on the working state and that induced the self-oscillations into the equipment structure.

  5. Effect of dynamic monotonic and cyclic loading on fracture behavior for Japanese carbon steel pipe STS410

    Energy Technology Data Exchange (ETDEWEB)

    Kinoshita, Kanji; Murayama, Kouichi; Ogata, Hiroyuki [and others

    1997-04-01

    The fracture behavior for Japanese carbon steel pipe STS410 was examined under dynamic monotonic and cyclic loading through a research program of International Piping Integrity Research Group (EPIRG-2), in order to evaluate the strength of pipe during the seismic event The tensile test and the fracture toughness test were conducted for base metal and TIG weld metal. Three base metal pipe specimens, 1,500mm in length and 6-inch diameter sch.120, were employed for a quasi-static monotonic, a dynamic monotonic and a dynamic cyclic loading pipe fracture tests. One weld joint pipe specimen was also employed for a dynamic cyclic loading test In the dynamic cyclic loading test, the displacement was controlled as applying the fully reversed load (R=-1). The pipe specimens with a circumferential through-wall crack were subjected four point bending load at 300C in air. Japanese STS410 carbon steel pipe material was found to have high toughness under dynamic loading condition through the CT fracture toughness test. As the results of pipe fracture tests, the maximum moment to pipe fracture under dynamic monotonic and cyclic loading condition, could be estimated by plastic collapse criterion and the effect of dynamic monotonic loading and cyclic loading was a little on the maximum moment to pipe fracture of the STS410 carbon steel pipe. The STS410 carbon steel pipe seemed to be less sensitive to dynamic and cyclic loading effects than the A106Gr.B carbon steel pipe evaluated in IPIRG-1 program.

  6. Effect of dynamic monotonic and cyclic loading on fracture behavior for Japanese carbon steel pipe STS410

    International Nuclear Information System (INIS)

    Kinoshita, Kanji; Murayama, Kouichi; Ogata, Hiroyuki

    1997-01-01

    The fracture behavior for Japanese carbon steel pipe STS410 was examined under dynamic monotonic and cyclic loading through a research program of International Piping Integrity Research Group (EPIRG-2), in order to evaluate the strength of pipe during the seismic event The tensile test and the fracture toughness test were conducted for base metal and TIG weld metal. Three base metal pipe specimens, 1,500mm in length and 6-inch diameter sch.120, were employed for a quasi-static monotonic, a dynamic monotonic and a dynamic cyclic loading pipe fracture tests. One weld joint pipe specimen was also employed for a dynamic cyclic loading test In the dynamic cyclic loading test, the displacement was controlled as applying the fully reversed load (R=-1). The pipe specimens with a circumferential through-wall crack were subjected four point bending load at 300C in air. Japanese STS410 carbon steel pipe material was found to have high toughness under dynamic loading condition through the CT fracture toughness test. As the results of pipe fracture tests, the maximum moment to pipe fracture under dynamic monotonic and cyclic loading condition, could be estimated by plastic collapse criterion and the effect of dynamic monotonic loading and cyclic loading was a little on the maximum moment to pipe fracture of the STS410 carbon steel pipe. The STS410 carbon steel pipe seemed to be less sensitive to dynamic and cyclic loading effects than the A106Gr.B carbon steel pipe evaluated in IPIRG-1 program

  7. Transient subcritical crack-growth behavior in transformation-toughened ceramics

    International Nuclear Information System (INIS)

    Dauskardt, R.H.; Ritchie, R.O.; Carter, W.C.; Veirs, D.K.

    1990-01-01

    Transient subcritical crack-growth behavior following abrupt changes in the applied load are studied in transformation-toughened ceramics. A mechanics analysis is developed to model the transient nature of transformation shielding of the crack tip, K s , with subcritical crack extension following the applied load change. conditions for continued crack growth, crack growth followed by arrest, and no crack growth after the load change, are considered and related to the magnitude and sign of the applied load change and to materials properties such as the critical transformation stress. The analysis is found to provide similar trends in K s compared to values calculated from experimentally measured transformation zones in a transformation-toughened Mg-PSZ. In addition, accurate prediction of the post load-change transient crack-growth behavior is obtained using experimentally derived steady-state subcritical crack-growth relationships for cyclic fatigue in the same material

  8. Feedback control systems for non-linear simulation of operational transients in LMFBRs

    International Nuclear Information System (INIS)

    Khatib-Rahbar, M.; Agrawal, A.K.; Srinivasan, E.S.

    Adequate modeling of Plant Control Systems (PCS) for the study of Anticipated Transients Without Scram (ATWS) is of considerable significance in the design, operation and safety evaluation of Liquid-Metal-Cooled Fast Breeder Reactor (LMFBR) systems. To assess the system response to high frequency, low consequence events, the plant needs to be dynamically simulated. The description of analytical and numerical models for PCS that have been developed and incorporated into the loop version of the Super System Code (SSC-L) are described. The importance of detailed modeling of control systems is discussed. Sample transient results obtained for a 10% ramp change of load in 40 s in the Clinch River Breeder Reactor Plant (CRBRP) are also shown

  9. Effects of self-coupling and asymmetric output on metastable dynamical transient firing patterns in arrays of neurons with bidirectional inhibitory coupling.

    Science.gov (United States)

    Horikawa, Yo

    2016-04-01

    Metastable dynamical transient patterns in arrays of bidirectionally coupled neurons with self-coupling and asymmetric output were studied. First, an array of asymmetric sigmoidal neurons with symmetric inhibitory bidirectional coupling and self-coupling was considered and the bifurcations of its steady solutions were shown. Metastable dynamical transient spatially nonuniform states existed in the presence of a pair of spatially symmetric stable solutions as well as unstable spatially nonuniform solutions in a restricted range of the output gain of a neuron. The duration of the transients increased exponentially with the number of neurons up to the maximum number at which the spatially nonuniform steady solutions were stabilized. The range of the output gain for which they existed reduced as asymmetry in a sigmoidal output function of a neuron increased, while the existence range expanded as the strength of inhibitory self-coupling increased. Next, arrays of spiking neuron models with slow synaptic inhibitory bidirectional coupling and self-coupling were considered with computer simulation. In an array of Class 1 Hindmarsh-Rose type models, in which each neuron showed a graded firing rate, metastable dynamical transient firing patterns were observed in the presence of inhibitory self-coupling. This agreed with the condition for the existence of metastable dynamical transients in an array of sigmoidal neurons. In an array of Class 2 Bonhoeffer-van der Pol models, in which each neuron had a clear threshold between firing and resting, long-lasting transient firing patterns with bursting and irregular motion were observed. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. The dynamic behavior of mortar under impact-loading

    Science.gov (United States)

    Kawai, Nobuaki; Inoue, Kenji; Misawa, Satoshi; Tanaka, Kyoji; Hayashi, Shizuo; Kondo, Ken-Ichi; Riedel, Werner

    2007-06-01

    Concrete and mortar are the most fundamental structural material. Therefore, considerable interest in characterizing the dynamic behavior of them under impact-loading exists. In this study, plate impact experiments have been performed to determine the dynamic behavior of mortar. Longitudinal and lateral stresses have been directly measured by means of embedded polyvinylidene fluoride (PVDF) gauges up to 1 GPa. A 200 mm-cal. powder gun enable us to measure longitudinal and lateral stresses at several point from the impact surface, simultaneously. The shear strength under impact-loading has been obtained from measured longitudinal and lateral stresses. The longitudinal stress profile shows a two-wave structure. It is indicated that this structure is associated with the onset of pore compaction and failure of mortar by comparing with hydrocode simulations using an elastic-plastic damage model for concrete.

  11. Dynamic fracture initiation in brittle materials under combined mode I/II loading

    International Nuclear Information System (INIS)

    Nakano, M.; Kishida, K.; Yamauchi, Y.; Sogabe, Y.

    1994-01-01

    A new test method has been developed to measure the resistance of dynamic fracture initiation in brittle materials under combined mode I/II loadings. The Brazilian disks with center-cracks have been fractured under oblique impact loadings in diametral-compression. The dynamic stress intensity factors of mode I and II are evaluated from the superposition integrals of the step response functions for the cracked disk. The experimental results are presented to elucidate the influence of loading rate on the combined mode fracture toughness for ceramics and glasses. (orig.)

  12. Dynamical cancellation of pulse-induced transients in a metallic shielded room for ultra-low-field magnetic resonance imaging

    International Nuclear Information System (INIS)

    Zevenhoven, Koos C. J.; Ilmoniemi, Risto J.; Dong, Hui; Clarke, John

    2015-01-01

    Pulse-induced transients such as eddy currents can cause problems in measurement techniques where a signal is acquired after an applied preparatory pulse. In ultra-low-field magnetic resonance imaging, performed in magnetic fields typically of the order of 100 μT, the signal-to-noise ratio is enhanced in part by prepolarizing the proton spins with a pulse of much larger magnetic field and in part by detecting the signal with a Superconducting QUantum Interference Device (SQUID). The pulse turn-off, however, can induce large eddy currents in the shielded room, producing an inhomogeneous magnetic-field transient that both seriously distorts the spin dynamics and exceeds the range of the SQUID readout. It is essential to reduce this transient substantially before image acquisition. We introduce dynamical cancellation (DynaCan), a technique in which a precisely designed current waveform is applied to a separate coil during the later part and turn off of the polarizing pulse. This waveform, which bears no resemblance to the polarizing pulse, is designed to drive the eddy currents to zero at the precise moment that the polarizing field becomes zero. We present the theory used to optimize the waveform using a detailed computational model with corrections from measured magnetic-field transients. SQUID-based measurements with DynaCan demonstrate a cancellation of 99%. Dynamical cancellation has the great advantage that, for a given system, the cancellation accuracy can be optimized in software. This technique can be applied to both metal and high-permeability alloy shielded rooms, and even to transients other than eddy currents

  13. Resonant and off-resonant transients in electromagnetically induced transparency: Turn-on and turn-off dynamics

    International Nuclear Information System (INIS)

    Greentree, Andrew D.; Smith, T.B.; Echaniz, S.R. de; Durrant, A. V.; Marangos, J.P.; Segal, D.M.; Vaccaro, J.A.

    2002-01-01

    This paper presents a wide-ranging theoretical and experimental study of nonadiabatic transient phenomena in a Λ electromagnetically induced transparency system when a strong coupling field is rapidly switched on or off. The theoretical treatment uses a Laplace transform approach to solve the time-dependent density matrix equation. The experiments are carried out in a 87 Rb magneto-optical trap. The results show transient probe gain in parameter regions not previously studied, and provide insight into the transition dynamics between bare and dressed states

  14. Numerical methods and parallel algorithms for fast transient strongly coupled fluid-structure dynamics

    International Nuclear Information System (INIS)

    Faucher, V.

    2014-01-01

    This HDR is dedicated to the research in the framework of fast transient dynamics for industrial fluid-structure systems carried in the Laboratory of Dynamic Studies from CEA, implementing new numerical methods for the modelling of complex systems and the parallel solution of large coupled problems on supercomputers. One key issue for the proposed approaches is the limitation to its minimum of the number of non-physical parameters, to cope with constraints arising from the area of usage of the concepts: safety for both nuclear applications (CEA, EDF) and aeronautics (ONERA), protection of the citizen (EC/JRC) in particular. Kinematic constraints strongly coupling structures (namely through unilateral contact) or fluid and structures (with both conformant or non-conformant meshes depending on the geometrical situation) are handled through exact methods including Lagrange Multipliers, with consequences on the solution strategy to be dealt with. This latter aspect makes EPX, the simulation code where the methods are integrated, a singular tool in the community of fast transient dynamics software. The document mainly relies on a description of the modelling needs for industrial fast transient scenarios, for nuclear applications in particular, and the proposed solutions built in the framework of the collaboration between CEA, EDF (via the LaMSID laboratory) and the LaMCoS laboratory from INSA Lyon. The main considered examples are the tearing of the fluid-filled tank after impact, the Code Disruptive Accident for a Generation IV reactor or the ruin of reinforced concrete structures under impact. Innovative models and parallel algorithms are thus proposed, allowing to carry out with robustness and performance the corresponding simulations on supercomputers made of interconnected multi-core nodes, with a strict preservation of the quality of the physical solution. This was particularly the main point of the ANR RePDyn project (2010-2013), with CEA as the pilot. (author

  15. Transient hepatic attenuation difference of lobar or segmental distribution detected by dynamic computed tomography

    International Nuclear Information System (INIS)

    Itai, Y.; Moss, A.A.; Goldberg, H.I.

    1982-01-01

    Dynamic computed tomography of hepatic tumors revealed a transient attenuation difference of the liver in a lobar or segmental distribution in three cases. The difference was most prominent during the hepatogram phase. It was attributed to siphonage of arterial blood by hepatic tumors in two cases, while an increase of arterial flow induced by portal vein occlusion was inferred in the other case. Results indicate dynamic computed tomography will be usful in analysis of geometrical hemodynamics

  16. Shaft Center Orbit in Dynamically Loaded Bearings

    DEFF Research Database (Denmark)

    Klit, Peder

    2005-01-01

    The aim of this work is to demonstrate how to utilize the bearings damping coe±cients to estimate the orbit for a dynamically loaded journal bearing. The classical method for this analysis was developed by Booker in 1965 [1]and described further in 1972 [2]. Several authors have re¯ned this metho...

  17. Applicability of laboratory data to large scale tests under dynamic loading conditions

    International Nuclear Information System (INIS)

    Kussmaul, K.; Klenk, A.

    1993-01-01

    The analysis of dynamic loading and subsequent fracture must be based on reliable data for loading and deformation history. This paper describes an investigation to examine the applicability of parameters which are determined by means of small-scale laboratory tests to large-scale tests. The following steps were carried out: (1) Determination of crack initiation by means of strain gauges applied in the crack tip field of compact tension specimens. (2) Determination of dynamic crack resistance curves of CT-specimens using a modified key-curve technique. The key curves are determined by dynamic finite element analyses. (3) Determination of strain-rate-dependent stress-strain relationships for the finite element simulation of small-scale and large-scale tests. (4) Analysis of the loading history for small-scale tests with the aid of experimental data and finite element calculations. (5) Testing of dynamically loaded tensile specimens taken as strips from ferritic steel pipes with a thickness of 13 mm resp. 18 mm. The strips contained slits and surface cracks. (6) Fracture mechanics analyses of the above mentioned tests and of wide plate tests. The wide plates (960x608x40 mm 3 ) had been tested in a propellant-driven 12 MN dynamic testing facility. For calculating the fracture mechanics parameters of both tests, a dynamic finite element simulation considering the dynamic material behaviour was employed. The finite element analyses showed a good agreement with the simulated tests. This prerequisite allowed to gain critical J-integral values. Generally the results of the large-scale tests were conservative. 19 refs., 20 figs., 4 tabs

  18. Effects of External Loads on Human Head Movement Control Systems

    Science.gov (United States)

    Nam, M. H.; Choi, O. M.

    1984-01-01

    The central and reflexive control strategies underlying movements were elucidated by studying the effects of external loads on human head movement control systems. Some experimental results are presented on dynamic changes weigh the addition of aviation helmet (SPH4) and lead weights (6 kg). Intended time-optimal movements, their dynamics and electromyographic activity of neck muscles in normal movements, and also in movements made with external weights applied to the head were measured. It was observed that, when the external loads were added, the subject went through complex adapting processes and the head movement trajectory and its derivatives reached steady conditions only after transient adapting period. The steady adapted state was reached after 15 to 20 seconds (i.e., 5 to 6 movements).

  19. Dynamic Loads and Wake Prediction for Large Wind Turbines Based on Free Wake Method

    Institute of Scientific and Technical Information of China (English)

    Cao Jiufa; Wang Tongguang; Long Hui; Ke Shitang; Xu Bofeng

    2015-01-01

    With large scale wind turbines ,the issue of aerodynamic elastic response is even more significant on dy-namic behaviour of the system .Unsteady free vortex wake method is proposed to calculate the shape of wake and aerodynamic load .Considering the effect of aerodynamic load ,inertial load and gravity load ,the decoupling dy-namic equations are established by using finite element method in conjunction of the modal method and equations are solved numerically by Newmark approach .Finally ,the numerical simulation of a large scale wind turbine is performed through coupling the free vortex wake modelling with structural modelling .The results show that this coupling model can predict the flexible wind turbine dynamic characteristics effectively and efficiently .Under the influence of the gravitational force ,the dynamic response of flapwise direction contributes to the dynamic behavior of edgewise direction under the operational condition of steady wind speed .The difference in dynamic response be-tween the flexible and rigid wind turbines manifests when the aerodynamics/structure coupling effect is of signifi-cance in both wind turbine design and performance calculation .

  20. Dynamic Aftershock Triggering Correlated with Cyclic Loading in the Slip Direction

    Science.gov (United States)

    Hardebeck, J.

    2014-12-01

    Dynamic stress changes have been shown to contribute to aftershock triggering, but the physical triggering mechanisms are not fully understood. Some proposed mechanisms are based on dynamic stress loading of the target fault in a direction that encourages earthquake slip (e.g. dynamic Coulomb stress triggering), while other mechanisms are based on fault weakening due to shaking. If dynamic stress loading in the fault slip direction plays a role in aftershock triggering, we would expect to see a relationship between the dynamic stress orientations and the aftershock focal mechanisms. Alternatively, if dynamic stress change triggering functions only through a fault weakening mechanism that is independent of the slip direction of the target fault, no such relationship is expected. I study aftershock sequences of 4 M≥6.7 mainshocks in southern California, and find a small but significant relationship between modeled dynamic stress direction and aftershock focal mechanisms. The mainshock dynamic stress changes have two observed impacts: changing the focal mechanisms in a given location to favor those aligned with the dynamic stress change, and changing the spatial distribution of seismicity to favor locations where the dynamic stress change aligns with the background stress. The aftershock focal mechanisms are significantly more aligned with the dynamic stress changes than the preshock mechanisms for only the first 0.5-1 year following most mainshocks, although for at least 10 years following Hector Mine. Dynamic stress effects on focal mechanisms are best observed at long periods (30-60 sec). Dynamic stress effects are only observed when using metrics based on repeated stress cycling in the same direction, for example considering the dominant stress orientation over the full time series, and not for the peak dynamic stress. These results imply that dynamic aftershock triggering operates at least in part through cyclic loading in the direction of fault slip, although

  1. Dynamic CT of portal hypertensive gastropathy: significance of transient gastric perfusion defect sign

    International Nuclear Information System (INIS)

    Kim, T.U.; Kim, S.; Woo, S.K.; Lee, J.W.; Lee, T.H.; Jeong, Y.J.; Heo, J.

    2008-01-01

    Aim: To evaluate the 'transient gastric perfusion defect' sign as a way of diagnosing portal hypertensive gastropathy (PHG) on multidetector computed tomography (CT). Materials and methods: Ninety-two consecutive patients with cirrhosis underwent three-phase CT and endoscopy. Endoscopy was performed within 3 days of the CT examination. As controls, 92 patients without clinical evidence of chronic liver diseases who underwent CT and endoscopy were enrolled; the findings at endoscopy were used as a reference standard for patients with PHG. Two radiologists who were unaware of the results of the endoscopy retrospectively interpreted the CT images. PHG was diagnosed on dynamic CT if the transient gastric perfusion defect sign was present. The transient gastric perfusion defect was defined as the presence of transient, segmental or subsegmental hypo-attenuating mucosa in the fundus or body of the stomach on hepatic arterial imaging that returned to normal attenuation on portal venous or equilibrium-phase imaging. The frequency of the transient gastric perfusion defect sign was compared between these two groups using Fisher's exact test. The frequency, sensitivity, specificity, positive predictive values, and negative predictive values of the transient gastric perfusion defect sign were also compared between patients with PHG and without PHG in the cirrhosis group. Results: Nine patients of 92 patients with cirrhosis were excluded because of previous procedure or motion artifact; the remaining 83 patients with cirrhosis were evaluated. In the cirrhosis group, 40 (48.1%) of 83 patients showed the transient gastric perfusion defect sign. In the control group, none of the 92 patients showed the transient gastric perfusion defect sign. In the cirrhotic group, the frequency of the transient gastric perfusion defect sign was significantly higher in the patients with PHG (75%, 36/48) than in patients without PHG (11.4%, 4/35). The sensitivity, specificity, positive predictive

  2. A generalized modal shock spectra method for spacecraft loads analysis. [internal loads in a spacecraft structure subjected to a dynamic launch environment

    Science.gov (United States)

    Trubert, M.; Salama, M.

    1979-01-01

    Unlike an earlier shock spectra approach, generalization permits an accurate elastic interaction between the spacecraft and launch vehicle to obtain accurate bounds on the spacecraft response and structural loads. In addition, the modal response from a previous launch vehicle transient analysis with or without a dummy spacecraft - is exploited to define a modal impulse as a simple idealization of the actual forcing function. The idealized modal forcing function is then used to derive explicit expressions for an estimate of the bound on the spacecraft structural response and forces. Greater accuracy is achieved with the present method over the earlier shock spectra, while saving much computational effort over the transient analysis.

  3. Transient multivariable sensor evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Vilim, Richard B.; Heifetz, Alexander

    2017-02-21

    A method and system for performing transient multivariable sensor evaluation. The method and system includes a computer system for identifying a model form, providing training measurement data, generating a basis vector, monitoring system data from sensor, loading the system data in a non-transient memory, performing an estimation to provide desired data and comparing the system data to the desired data and outputting an alarm for a defective sensor.

  4. Transient Beam Dynamics in the LBL 2 MV Injector

    International Nuclear Information System (INIS)

    Henestroza, E; Grote, D

    1999-01-01

    A driver-scale injector for the Heavy Ion Fusion Accelerator project has been built at LBL. This machine has exceeded the design goals of high voltage (> 2 MV), high current (> 0.8 A of K + ) and low normalized emittance (< 1 π mm-mr). The injector consists of a 750 keV gun pre-injector followed by an electrostatic quadrupole accelerator (ESQ) which provides strong (alternating gradient) focusing for the space-charge dominated beam, and simultaneously accelerates the ions to 2 MeV. A matching section is being built to match the beam to the electrostatic accelerator ELISE. The gun preinjector, designed to hold up to 1 MV with minimal breakdown risks, consists of a hot aluminosilicate source with a large curved emitting surface surrounded by a thick ''extraction electrode''. During beam turn-on the voltage at the source is biased from a negative potential, enough to reverse the electric field on the emitting surface and avoid emission, to a positive potential to start extracting the beam; it stays constant for about 1 (micro)s, and is reversed to turn-off the emission. Since the Marx voltage applied on the accelerating quadrupoles and the main pre-injector gap is a long, constant pulse (several (micro)s), the transient behavior is dominated by the extraction pulser voltage time profile. The transient longitudinal dynamics of the beam in the injector was simulated by running the Particle in Cell codes GYMNOS and WARP3d in a time dependent mode. The generalization and its implementation in WAIW3d of a method proposed by Lampel and Tiefenback to eliminate transient oscillations in a one-dimensional planar diode will be presented

  5. Comparative first- and second-law parametric study of transient diesel engine operation

    International Nuclear Information System (INIS)

    Rakopoulos, C.D.; Giakoumis, E.G.

    2006-01-01

    A computer model is developed for studying the first- and second-law (availability) balances of a turbocharged diesel engine, operating under transient load conditions. Special attention is paid to the direct comparison between the results from the two laws, for various operating parameters of the engine. The model simulates the transient operation on a degree crank angle basis, using a detailed analysis of mechanical friction, a separate consideration for the processes of each cylinder during a cycle ('multi-cylinder' model) and a mathematical model of the fuel pump. Experimental data taken from a marine duty, turbocharged diesel engine, located at the authors' laboratory, are used for the evaluation of the model's predictive capabilities. The first-law (e.g., engine speed, fuel pump rack position, engine load, etc.) and second-law (e.g., irreversibilities, heat loss and exhaust gases) terms for the diesel engine cylinder are both computed and depicted in comparison, using detailed diagrams, for various engine operating parameters. It is revealed that, at least for the specific engine type and operation, a thermodynamic, dynamic or design parameter can have a conflicting impact on the engine transient response as regards energy and availability properties, implying that both a first- and second-law optimization is needed for best performance evaluation

  6. Effect of Static-Dynamic Coupling Loading on Fracture Toughness and Failure Characteristics in Marble

    Directory of Open Access Journals (Sweden)

    Z. Q. Yin

    2014-03-01

    Full Text Available Fracture experiments in a notched semi-circular bend configuration were conducted to test the dynamic fracture toughness of a marble under static-dynamic coupling load using a modified split Hopkinson pressure bar. The fracture process of the specimen was monitored using a high speed (HS camera. Based on digital image correlation (DIC and strain gauges, the full-field strain fields and time-to-fracture of the marble were measured under static-dynamic coupling load. Experimental results show that dynamic fracture toughness was well determined, and the HS-DIC technique provides reliable full-field strain fields in the specimens under static-dynamic coupling loads. The failure characteristics of the marble under external impact were affected obviously by pre-compression stress. Increase of axial pre-compression stress was helpful to improve the crack propagation velocity, and dynamic crack initiation toughness was decreased.

  7. Influence of the implant abutment types and the dynamic loading on initial screw loosening

    Science.gov (United States)

    Kim, Eun-Sook

    2013-01-01

    PURPOSE This study examined the effects of the abutment types and dynamic loading on the stability of implant prostheses with three types of implant abutments prepared using different fabrication methods by measuring removal torque both before and after dynamic loading. MATERIALS AND METHODS Three groups of abutments were produced using different types of fabrication methods; stock abutment, gold cast abutment, and CAD/CAM custom abutment. A customized jig was fabricated to apply the load at 30° to the long axis. The implant fixtures were fixed to the jig, and connected to the abutments with a 30 Ncm tightening torque. A sine curved dynamic load was applied for 105 cycles between 25 and 250 N at 14 Hz. Removal torque before loading and after loading were evaluated. The SPSS was used for statistical analysis of the results. A Kruskal-Wallis test was performed to compare screw loosening between the abutment systems. A Wilcoxon signed-rank test was performed to compare screw loosening between before and after loading in each group (α=0.05). RESULTS Removal torque value before loading and after loading was the highest in stock abutment, which was then followed by gold cast abutment and CAD/CAM custom abutment, but there were no significant differences. CONCLUSION The abutment types did not have a significant influence on short term screw loosening. On the other hand, after 105 cycles dynamic loading, CAD/CAM custom abutment affected the initial screw loosening, but stock abutment and gold cast abutment did not. PMID:23509006

  8. Dynamical Model of Rocket Propellant Loading with Liquid Hydrogen

    Data.gov (United States)

    National Aeronautics and Space Administration — A dynamical model describing the multi-stage process of rocket propellant loading has been developed. It accounts for both the nominal and faulty regimes of...

  9. Dynamic load balancing algorithm for molecular dynamics based on Voronoi cells domain decompositions

    Energy Technology Data Exchange (ETDEWEB)

    Fattebert, J.-L. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Richards, D.F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Glosli, J.N. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2012-12-01

    We present a new algorithm for automatic parallel load balancing in classical molecular dynamics. It assumes a spatial domain decomposition of particles into Voronoi cells. It is a gradient method which attempts to minimize a cost function by displacing Voronoi sites associated with each processor/sub-domain along steepest descent directions. Excellent load balance has been obtained for quasi-2D and 3D practical applications, with up to 440·106 particles on 65,536 MPI tasks.

  10. Effects of the Pressurized Water Reactor Main Steam Line Break Location on the Blowdown Loading

    International Nuclear Information System (INIS)

    Jo, Jong Chull; Kang, Soon Ho; Chan, Won Joon

    2016-01-01

    The thermal hydraulic analysis has been performed generally using a simple lumped model or one dimensional numerical model. However, those models have limitations in predicting the transient variations of the steam velocity, pressure and hydrodynamic load at a local point and the most conservative condition. Furthermore, it cannot be confirmed if the blowdown loads predicted by either of the models are conservative to evaluate every part of the SG internal structures. In this study, the transient hydraulic response of the SG secondary side to the MSLB case where the pipe break is assumed to occur at the SG outlet nozzle end, another weld point on the MSL, was numerically simulated using a CFD code. The present CFD calculation results was compared with those in ref. to investigate the effect of break location (friction loss) on the blowdown load in the SG secondary side. The result shows that the friction loss along the steam line span between the SG nozzle end and the MSIV would cause reduction in steam velocity disturbance or dynamic pressure. It implies that the consequence of the MSLB at the SG nozzle end would be much severer that those of other MSLB cases where the break locations are far from the SG. Therefore, to assure a conservative safety evaluation of the SG structural integrity, the blowdown loading on the SG internal structures including tubes during a MSLB accident in terms of the transient steam velocity, dynamic pressure and decompression wave fluctuations should be assessed for the MSLB case where the break is assumed to occur at the SG nozzle end.

  11. Effects of the Pressurized Water Reactor Main Steam Line Break Location on the Blowdown Loading

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Jong Chull; Kang, Soon Ho; Chan, Won Joon [KAERI, Daejeon (Korea, Republic of)

    2016-05-15

    The thermal hydraulic analysis has been performed generally using a simple lumped model or one dimensional numerical model. However, those models have limitations in predicting the transient variations of the steam velocity, pressure and hydrodynamic load at a local point and the most conservative condition. Furthermore, it cannot be confirmed if the blowdown loads predicted by either of the models are conservative to evaluate every part of the SG internal structures. In this study, the transient hydraulic response of the SG secondary side to the MSLB case where the pipe break is assumed to occur at the SG outlet nozzle end, another weld point on the MSL, was numerically simulated using a CFD code. The present CFD calculation results was compared with those in ref. to investigate the effect of break location (friction loss) on the blowdown load in the SG secondary side. The result shows that the friction loss along the steam line span between the SG nozzle end and the MSIV would cause reduction in steam velocity disturbance or dynamic pressure. It implies that the consequence of the MSLB at the SG nozzle end would be much severer that those of other MSLB cases where the break locations are far from the SG. Therefore, to assure a conservative safety evaluation of the SG structural integrity, the blowdown loading on the SG internal structures including tubes during a MSLB accident in terms of the transient steam velocity, dynamic pressure and decompression wave fluctuations should be assessed for the MSLB case where the break is assumed to occur at the SG nozzle end.

  12. Modeling of Transient Response of the Wickless Heat Pipes

    International Nuclear Information System (INIS)

    Hussien, A.K.A.

    2013-01-01

    Thermosyphons transient response for startup from ambient temperature to steady state until shutdown conditions, is considered a stringent necessity for applications such as electronic, solar, geothermal and even nuclear reactors safety systems. This typically returns to the need to keep the temperature within certain limits before reaching critical conditions. A simple network model is derived for describing the transient response of closed two-phase thermosyphon (CTPT) at startup and shutdown states. In addition, for predicting the effect of operational characteristics of water/copper closed two-phase thermosyphon such as thermal load, filling ratio, evaporator length, and thermosyphon tube diameter. The thermosyphons operation was considered a thermal network of various components with different thermal resistances and dynamic responses. The network model consists of six sub-models. These models are pure conduction in walls of evaporator, adiabatic and condenser, and convection in evaporator pool, evaporator film, and condenser film. So, an energy balance for each sub-model was done to estimate temperatures, heat transfer coefficients, thermal resistances, time constant, and other thermal characteristics that describe the required transient response of the closed two-phase thermosyphon. Governing equations of the transient thermosyphon behavior can be simplified into a set of first-order linear ordinary differential equations. The Runge-Kutta method can be used to obtain transient thermosyphon temperatures from these equations.

  13. Strength and behavior in shear of reinforced concrete deep beams under dynamic loading conditions

    Energy Technology Data Exchange (ETDEWEB)

    Adhikary, Satadru Das [School of Civil and Environmental Engineering, Nanyang Technological University, 639798 (Singapore); Li, Bing, E-mail: cbli@ntu.edu.sg [School of Civil and Environmental Engineering, Nanyang Technological University, 639798 (Singapore); Fujikake, Kazunori [Department of Civil and Environmental Engineering, National Defense Academy, Yokosuka 239 8686 (Japan)

    2013-06-15

    Highlights: ► Effects of wider range of loading rates on dynamic shear behavior of RC deep beams. ► Experimental investigation of RC deep beam with and without shear reinforcements. ► Verification of experimental results with truss model and FE simulation results. ► Empirical equations are proposed to predict the dynamic increase factor of maximum resistance. -- Abstract: Research on reinforced concrete (RC) deep beams has seen considerable headway over the past three decades; however, information on the dynamic shear strength and behavior of RC deep beams under varying rates of loads remains limited. This paper describes the experimental results of 24 RC deep beams with and without shear reinforcements under varying rates of concentrated loading. Results obtained serve as useful data on shear resistance, failure patterns and strain rates corresponding to varying loading rates. An analytical truss model approach proves its efficacy in predicting the dynamic shear resistance under varying loading rates. Furthermore, three-dimensional nonlinear finite element (FE) model is described and the simulation results are verified with the experimental results. A parametric study is then conducted to investigate the influence of longitudinal reinforcement ratio, transverse reinforcement ratio and shear span to effective depth ratio on shear behavior. Subsequently, two empirical equations were proposed by integrating the various parameters to assess the dynamic increase factor (DIF) of maximum resistance under varying rates of concentrated loading.

  14. A pulsed load model and its impact on a synchronous-rectifier system

    Science.gov (United States)

    Hou, Pengfei; Xu, Ye; Li, Jianke; Wang, Jinquan; Zhang, Haitao; Yan, Jun; Wang, Chunming; Chen, Jingjing

    2017-02-01

    The pulsed load has become a developing trend of power loading. Unlike traditional loads, pulsed loads with current abrupt and repeated charges will result in unstable Microgrid operations because of their small capacity and inertia. In this paper, an Average Magnitude Sum Function (AMSF) is proposed to calculate the frequency of the grid, and based on AMSF, the Relative Deviation Rate (RDR) that characterises the impact of pulsed load on the AC side of the grid is defined and its calculation process is described in detail. In addition, the system dynamic characteristics under a pulsed load are analysed using an Insulated Gate Bipolar Transistor (IGBT) to control the on/off state of the resistive load for simulating a pulsed load. Finally, the transient characteristics of a synchronous-rectifier system with a pulsed load are studied and validated experimentally.

  15. Dynamic Load Balanced Clustering using Elitism based Random Immigrant Genetic Approach for Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    K. Mohaideen Pitchai

    2017-07-01

    Full Text Available Wireless Sensor Network (WSN consists of a large number of small sensors with restricted energy. Prolonged network lifespan, scalability, node mobility and load balancing are important needs for several WSN applications. Clustering the sensor nodes is an efficient technique to reach these goals. WSN have the characteristics of topology dynamics because of factors like energy conservation and node movement that leads to Dynamic Load Balanced Clustering Problem (DLBCP. In this paper, Elitism based Random Immigrant Genetic Approach (ERIGA is proposed to solve DLBCP which adapts to topology dynamics. ERIGA uses the dynamic Genetic Algorithm (GA components for solving the DLBCP. The performance of load balanced clustering process is enhanced with the help of this dynamic GA. As a result, the ERIGA achieves to elect suitable cluster heads which balances the network load and increases the lifespan of the network.

  16. Impact of large beam-induced heat loads on the transient operation of the beam screens and the cryogenic plants of the Future Circular Collider (FCC)

    Science.gov (United States)

    Correia Rodrigues, H.; Tavian, L.

    2017-12-01

    The Future Circular Collider (FCC) under study at CERN will produce 50-TeV high-energy proton beams. The high-energy particle beams are bent by 16-T superconducting dipole magnets operating at 1.9 K and distributed over a circumference of 80 km. The circulating beams induce 5 MW of dynamic heat loads by several processes such as synchrotron radiation, resistive dissipation of beam image currents and electron clouds. These beam-induced heat loads will be intercepted by beam screens operating between 40 and 60 K and induce transients during beam injection. Energy ramp-up and beam dumping on the distributed beam-screen cooling loops, the sector cryogenic plants and the dedicated circulators. Based on the current baseline parameters, numerical simulations of the fluid flow in the cryogenic distribution system during a beam operation cycle were performed. The effects of the thermal inertia of the headers on the helium flow temperature at the cryogenic plant inlet as well as the temperature gradient experienced by the beam screen has been assessed. Additionally, this work enabled a thorough exergetic analysis of different cryogenic plant configurations and laid the building-block for establishing design specification of cold and warm circulators.

  17. Dynamic Axle Load of an Automotive Vehicle When Driven on a Mobile Measurement Platform

    OpenAIRE

    Jagiełowicz-Ryznar C.

    2014-01-01

    An analysis of the dynamic axle load of an automotive vehicle (AV) when it is driven on a mobile measurement platform is presented in this paper. During the ride, the time characteristic of the dynamic force N(t), acting on the axle, was recorded. The effect of the vehicle axle mass on the maximum dynamic force value and the dynamic coefficient were studied. On this basis it was attempted to calculate the total vehicle’s weight. Conclusions concerning the dynamic loads of the vehicle axles in...

  18. Impact of the variation in dynamic vehicle load on flexible pavement responses

    Science.gov (United States)

    Ahsanuzzaman, Md

    The purpose of this research was to evaluate the dynamic variation in asphalt pavement critical responses due to dynamic tire load variations. An attempt was also made to develop generalized regression equations to predict the dynamic response variation in flexible pavement under various dynamic load conditions. The study used an extensive database of computed pavement response histories for five different types of sites (smooth, rough, medium rough, very rough and severely rough), two different asphalt pavement structures (thin and thick) at two temperatures (70 °F and 104 °F), subjected to a tandem axle dual tire at three speeds 25, 37 and 50 mph (40, 60 and 80 km/h). All pavement responses were determined using the 3D-Move Analysis program (Version 1.2) developed by University of Nevada, Reno. A new term called Dynamic Response Coefficient (DRC) was introduced in this study to address the variation in critical pavement responses due to dynamic loads as traditionally measured by the Dynamic Load Coefficient (DLC). While DLC represents the additional varying component of the tire load, DRC represents the additional varying component of the response value (standard deviation divided by mean response). In this study, DRC was compared with DLC for five different sites based on the roughness condition of the sites. Previous studies showed that DLC varies with vehicle speed and suspension types, and assumes a constant value for the whole pavement structure (lateral and vertical directions). On the other hand, in this study, DRC was found to be significantly varied with the asphalt pavement and function of pavement structure, road roughness conditions, temperatures, vehicle speeds, suspension types, and locations of the point of interest in the pavement. A major contribution of the study is that the variation of pavement responses due to dynamic load in a flexible pavement system can be predicted with generalized regression equations. Fitting parameters (R2) in the

  19. Efficient graph-based dynamic load-balancing for parallel large-scale agent-based traffic simulation

    NARCIS (Netherlands)

    Xu, Y.; Cai, W.; Aydt, H.; Lees, M.; Tolk, A.; Diallo, S.Y.; Ryzhov, I.O.; Yilmaz, L.; Buckley, S.; Miller, J.A.

    2014-01-01

    One of the issues of parallelizing large-scale agent-based traffic simulations is partitioning and load-balancing. Traffic simulations are dynamic applications where the distribution of workload in the spatial domain constantly changes. Dynamic load-balancing at run-time has shown better efficiency

  20. A neural model for transient identification in dynamic processes with 'don't know' response

    Energy Technology Data Exchange (ETDEWEB)

    Mol, Antonio C. de A. E-mail: mol@ien.gov.br; Martinez, Aquilino S. E-mail: aquilino@lmp.ufrj.br; Schirru, Roberto E-mail: schirru@lmp.ufrj.br

    2003-09-01

    This work presents an approach for neural network based transient identification which allows either dynamic identification or a 'don't know' response. The approach uses two 'jump' multilayer neural networks (NN) trained with the backpropagation algorithm. The 'jump' network is used because it is useful to dealing with very complex patterns, which is the case of the space of the state variables during some abnormal events. The first one is responsible for the dynamic identification. This NN uses, as input, a short set (in a moving time window) of recent measurements of each variable avoiding the necessity of using starting events. The other one is used to validate the instantaneous identification (from the first net) through the validation of each variable. This net is responsible for allowing the system to provide a 'don't know' response. In order to validate the method, a Nuclear Power Plant (NPP) transient identification problem comprising 15 postulated accidents, simulated for a pressurized water reactor (PWR), was proposed in the validation process it has been considered noisy data in order to evaluate the method robustness. Obtained results reveal the ability of the method in dealing with both dynamic identification of transients and correct 'don't know' response. Another important point studied in this work is that the system has shown to be independent of a trigger signal which indicates the beginning of the transient, thus making it robust in relation to this limitation.

  1. Expected load spectra of prototype Francis turbines in low-load operation using numerical simulations and site measurements

    Science.gov (United States)

    Eichhorn, M.; Taruffi, A.; Bauer, C.

    2017-04-01

    The operators of hydropower plants are forced to extend the existing operating ranges of their hydraulic machines to remain competitive on the energy market due to the rising amount of wind and solar power. Faster response times and a higher flexibility towards part- and low-load conditions enable a better electric grid control and assure therefore an economic operation of the power plant. The occurring disadvantage is a higher dynamic excitation of affected machine components, especially Francis turbine runners, due to pressure pulsations induced by unsteady flow phenomena (e.g. draft tube vortex ropes). Therefore, fatigue analysis becomes more important even in the design phase of the hydraulic machines to evaluate the static and dynamic load in different operating conditions and to reduce maintenance costs. An approach including a one-way coupled fluid-structure interaction has been already developed using unsteady CFD simulations and transient FEM computations. This is now applied on two Francis turbines with different specific speeds and power ranges, to obtain the load spectra of both machines. The results are compared to strain gauge measurements on the according Francis turbines to validate the overall procedure.

  2. Fatigue behaviour of core-spun yarns containing filament by means of cyclic dynamic loading

    Science.gov (United States)

    Esin, S.; Osman, B.

    2017-10-01

    The behaviour of yarns under dynamic loading is important that leads to understand the growth characteristics which is exposed to repetitive loadings during usage of fabric made from these yarns. Fabric growth is undesirable property that originated from low resilience characteristics of fabric. In this study, the effects of the filament fineness and yarn linear density on fatigue behaviour of rigid-core spun yarns were determined. Cotton covered yarns containing different filament fineness of polyester (PET) draw textured yarns (DTY) (100d/36f, 100d/96f, 100d/144f, 100d/192f and 100d/333f) and yarn linear densities (37 tex, 30 tex, 25 tex and 21 tex) were manufactured by using a modified ring spinning system at the same spinning parameters. Repetitive loads were applied for 25 cycles at levels between 0.1 and 3 N. Dynamic modulus and dynamic strain of yarn samples were analyzed statistically. Results showed that filament fineness and yarn linear density have significance effect on dynamic modulus and dynamic strain after cyclic loading.

  3. Transient and dynamic control of a variable speed wind turbine with synchronous generator

    Energy Technology Data Exchange (ETDEWEB)

    Jauch, Clemens [Riso National Laboratory, Wind Energy Department, PO Box 49, DK 4000 Roskilde, (Denmark)

    2007-02-14

    In this article, a controller for dynamic and transient control of a variable speed wind turbine with a full-scale converter-connected high-speed synchronous generator is presented. First, the phenomenon of drive train oscillations in wind turbines with full-scale converter-connected generators is discussed. Based on this discussion, a controller is presented that dampens these oscillations without impacting on the power that the wind turbine injects into the grid. Since wind turbines are increasingly demanded to take over power system stabilizing and control tasks, the presented wind turbine design is further enhanced to support the grid in transient grid events. A controller is designed that allows the wind turbine to ride through transient grid faults. Since such faults often cause power system oscillations, another controller is added that enables the turbine to participate in the damping of such oscillations. It is concluded that the controllers presented keep the wind turbine stable under any operating conditions, and that they are capable of adding substantial damping to the power system. (Author).

  4. Dynamic Magnification Factor in a Box-Shape Steel Girder

    Science.gov (United States)

    Rahbar-Ranji, A.

    2014-01-01

    The dynamic effect of moving loads on structures is treated as a dynamic magnification factor when resonant is not imminent. Studies have shown that the calculated magnification factors from field measurements could be higher than the values specified in design codes. It is the main aim of present paper to investigate the applicability and accuracy of a rule-based expression for calculation of dynamic magnification factor for lifting appliances used in marine industry. A steel box shape girder of a crane is considered and transient dynamic analysis using computer code ANSYS is implemented. Dynamic magnification factor is calculated for different loading conditions and compared with rule-based equation. The effects of lifting speeds, acceleration, damping ratio and position of cargo are examined. It is found that rule-based expression underestimate dynamic magnification factor.

  5. Analytical Modeling of Transient Process In Terms of One-Dimensional Problem of Dynamics With Kinematic Action

    Directory of Open Access Journals (Sweden)

    Kravets Victor V.

    2016-05-01

    Full Text Available One-dimensional dynamic design of a component characterized by inertia coefficient, elastic coefficient, and coefficient of energy dispersion. The component is affected by external action in the form of time-independent initial kinematic disturbances and varying ones. Mathematical model of component dynamics as well as a new form of analytical representation of transient in terms of one-dimensional problem of kinematic effect is provided. Dynamic design of a component is being carried out according to a theory of modal control.

  6. Turbofan compressor dynamics during afterburner transients

    Science.gov (United States)

    Kurkov, A. P.

    1976-01-01

    The effects of afterburner light-off and shut-down transients on the compressor stability are investigated. The reported experimental results are based on detailed high response pressure and temperature measurements on the TF30-P-3 turbofan engine. The tests were performed in an altitude test chamber simulating high altitude engine operation. It is shown that during both types of transients, flow breaks down in the forward part of the fan bypass duct. At a sufficiently low engine inlet pressure this resulted in a compressor stall. Complete flow breakdown within the compressor was preceded by a rotating stall. At some locations in the compressor, rotating stall cells initially extended only through part of the blade span. For the shutdown transient the time between first and last detected occurrence of rotating stall is related to the flow Reynolds number. An attempt was made to deduce the number and speed of propagation of rotating stall cells.

  7. EURDYN: computer programs for the nonlinear transient analysis of structures submitted to dynamic loading. EURDYN (Release 3): users' manual

    International Nuclear Information System (INIS)

    Halleux, J.P.

    1983-01-01

    The EURDYN computer codes are mainly designed for the simulation of nonlinear dynamic response of fast-reactor compoments submitted to impulse loading due to abnormal working conditions. Two releases of the structural computer codes EURDYN 01 (2-D beams and triangles and axisymmetric conical shells and triangular tores), 02 (axisymmetric and 2-D quadratic isoparametric elements) and 03 (triangular plate elements) have already been produced. They include material (elasto-plasticity using the classical flow theory approach) and geometrical (large displacements and rotations treated by a corotational technique) nonlinearities. The new features of Release 3 roughly consist in: full large strain capability for 9-node isoparametric elements, generalized array dimensions, introduction of the radial return algorithm for elasto-plastic material modelling, extension of the energy check facility to the case of prescribed displacements, and, possible interface to a post-processing package including time plot facilities

  8. On the dynamic stability of shear deformable beams under a tensile load

    Science.gov (United States)

    Caddemi, S.; Caliò, I.; Cannizzaro, F.

    2016-07-01

    Loss of stability of beams in a linear static context due to the action of tensile loads has been disclosed only recently in the scientific literature. However, tensile instability in the dynamic regime has been only marginally covered. Several aspects concerning the role of shear deformation on the tensile dynamic instability on continuous and discontinuous beams are still to be addressed. It may appear as a paradox, but also for the case of the universally studied Timoshenko beam model, despite its old origin, frequency-axial load diagrams in the range of negative values of the load (i.e. tensile load) has never been brought to light. In this paper, for the first time, the influence of a conservative tensile axial loads on the dynamic behaviour of the Timoshenko model, according to the Haringx theory, is assessed. It is shown that, under increasing tensile loads, regions of positive/negative fundamental frequency variations can be distinguished. In addition, the beam undergoes eigen-mode changes, from symmetric to anti-symmetric shapes, until tensile instability of divergence type is reached. As a further original contribution on the subject, taking advantage of a new closed form solution, it is shown that the same peculiarities are recovered for an axially loaded Euler-Bernoulli vibrating beam with multiple elastic sliders. This latter model can be considered as the discrete counterpart of the Timoshenko beam-column in which the internal sliders concentrate the shear deformation that in the Timoshenko model is continuously distributed. Original aspects regarding the evolution of the vibration frequencies and the relevant mode shapes with the tensile load value are highlighted.

  9. Effect of transients on the beam in the Superconducting Supercollider Coupled-Cavity Linac

    International Nuclear Information System (INIS)

    Young, L.M.; Nath, S.

    1992-01-01

    Each module of the Superconducting Super Collider (SSC) Coupled-Cavity Linac (CCL) consists of eight tanks (10 accelerating cells each) coupled with bridge couplers. The radio frequency (rf) power drive is in the center of the module at the bridge coupler between the fourth and fifth tanks. In this simulation of the beam dynamics, the rf power is turned on 10 μs before the beam is turned on. This time lapse allows the fields to build up and stabilize before they are required by the beam. When the beam is turned on, the beam loading causes the fields to change. This transient state of the fields together with their effect on the beam is presented. A model has been developed to calculate field distribution throughout the module as a function of time. Beam dynamics simulations were run with the results of this model at several times during the beam pulse. An estimate of the effect of the transients is given by the results of these simulations

  10. Influence of the implant abutment types and the dynamic loading on initial screw loosening

    OpenAIRE

    Kim, Eun-Sook; Shin, Soo-Yeon

    2013-01-01

    PURPOSE This study examined the effects of the abutment types and dynamic loading on the stability of implant prostheses with three types of implant abutments prepared using different fabrication methods by measuring removal torque both before and after dynamic loading. MATERIALS AND METHODS Three groups of abutments were produced using different types of fabrication methods; stock abutment, gold cast abutment, and CAD/CAM custom abutment. A customized jig was fabricated to apply the load at ...

  11. Characterization of electrical appliances in transient state

    Science.gov (United States)

    Wójcik, Augustyn; Winiecki, Wiesław

    2017-08-01

    The article contains the study about electrical appliance characterization on the basis of power grid signals. To represent devices, parameters of current and voltage signals recorded during transient states are used. In this paper only transients occurring as a result of switching on devices are considered. The way of data acquisition performed in specialized measurement setup developed for electricity load monitoring is described. The paper presents the method of transients detection and the method of appliance parameters calculation. Using the set of acquired measurement data and appropriate software the set of parameters for several household appliances operating in different operating conditions was processed. Usefulness of appliances characterization in Non-Intrusive Appliance Load Monitoring System (NIALMS) with the use of proposed method is discussed focusing on obtained results.

  12. Transient effects of sudden changes of heat load in a naturally ventilated room

    Science.gov (United States)

    Caulfield, C. P.; Bower, D. J.; Fitzgerald, S.; Woods, A. W.

    2006-11-01

    Using reduced numerical models and small-scale laboratory experiments, we investigate the transient effects of changing isolated heat loads discontinuously within a large, ventilated space. We consider the emptying filling box (with high and low openings) driven by a single isolated source of buoyancy. The original steady state consists of a buoyant layer, whose depth (for the simplest case of a point source plume) is determined by the geometric properties of the room alone. When the buoyancy flux of the source is increased, a new layer `fills' the room from the top with a more buoyant layer. The original layer disappears due to entrainment by the rising plume. The behaviour is qualitatively different when the source buoyancy flux is decreased. In this case, the rising plume fluid is now relatively dense, and so it inevitably collapses back to `intrude' below the original layer. In this case, the original layer disappears due to both draining through the upper opening, and penetrative entrainment by the dense plume. We compare the predictions of three numerical models using different penetrative entrainment parametrizations to a sequence of laboratory experiments. This entrainment reduces the density of the intruding layer, and so the rising plume eventually stalls, and no longer reaches the (draining) original layer. We demonstrate that it is necessary to consider the transient effects of penetrative entrainment when the reduction in source buoyancy flux is sufficiently small.

  13. CW 316 mechanical properties during thermal transients

    International Nuclear Information System (INIS)

    Cauvin, R.; Boutard, J.L.; Allegraud, G.

    1984-06-01

    During in pile incidents, the cladding can experience higher temperatures than the nominal one; it is necessary to know the mechanical properties of the cladding material during such thermal transients to predict the time and location of rupture. Two types of tests have been developed: first tensile (constant strain rate) tests after a heating at a constant rate and secondly constant load tests where heating is performed until rupture occurs. The tensile tests clearly show the role of the heating rate: the higher is the heating rate, the lower is the cold work recovery. Constant load tests were conducted with either uniaxial or biaxial (burst tests) loading. The same stress/failure temperature relation is found in both types of loading using the Von Mises equivalent stress. To predict failure, the Larson Miller parameter is not adequate, as well as all parameters based on a time/temperature equivalence. The yield stress measured in the two types of tests are very different probably due to a strain rate effect. Indeed the tensile tests are dynamic ones to avoid thermal recovery during the test duration, while the strain rate measured in constant load tests ranges only from 10 -5 s -1 to 10 -3 s -1 , being an increasing function of heating rate (ranging from 1 0 c/s to 100 0 c/s)

  14. Shaft centre orbit for dynamically loaded radial bearings

    DEFF Research Database (Denmark)

    Klit, Peder; Vølund, Anders

    2002-01-01

    The aim of this work is to demonstrate how to utilize the bearings damping coefficients to estimate the orbit for a dynamically loaded journal bearing. The classical method for this analysis was developed by Booker in 1965 Booker1 and described further in 1972 Booker2. Several authors have refine...

  15. Dynamic load effects on gate valve operability

    International Nuclear Information System (INIS)

    Steele, R. Jr.; MacDonald, P.E.; Arendts, J.G.

    1986-01-01

    The Idaho National Engineering Laboratory (INEL) participated in an internationally sponsored seismic research program conducted at the decommissioned Heissdampfreaktor (HDR) located in the Federal Republic of Germany. An existing piping system was modified by installation of an 8-in., naturally aged, motor-operated gate valve from a US nuclear power plant and a piping support system of US design. Six other piping support systems of varying flexibility from stiff to flexible were also installed at various times during the tests. Additional valve loadings included internal hydraulic loads and, during one block of tests, elevated temperature. The operability and integrity of the aged gate valve and the dynamic response of the various piping support system were measured during 25 representative seismic events

  16. Dynamic characteristics of a pump-turbine during hydraulic transients of a model pumped-storage system: 3D CFD simulation

    International Nuclear Information System (INIS)

    Zhang, X X; Cheng, Y G; Xia, L S; Yang, J D

    2014-01-01

    The runaway process in a model pumped-storage system was simulated for analyzing the dynamic characteristics of a pump-turbine. The simulation was adopted by coupling 1D (One Dimensional) pipeline MOC (Method of Characteristics) equations with a 3D (Three Dimensional) pump-turbine CFD (Computational Fluid Dynamics) model, in which the water hammer wave in the 3D zone was defined by giving a pressure dependent density. We found from the results that the dynamic performances of the pump-turbine do not coincide with the static operating points, especially in the S-shaped characteristics region, where the dynamic trajectories follow ring-shaped curves. Specifically, the transient operating points with the same Q 11 and M 11 in different moving directions of the dynamic trajectories give different n 11 . The main reason of this phenomenon is that the transient flow patterns inside the pump-turbine are influenced by the ones in the previous time step, which leads to different flow patterns between the points with the same Q 11 and M 11 in different moving directions of the dynamic trajectories

  17. Dynamic characteristics of a pump-turbine during hydraulic transients of a model pumped-storage system: 3D CFD simulation

    Science.gov (United States)

    Zhang, X. X.; Cheng, Y. G.; Xia, L. S.; Yang, J. D.

    2014-03-01

    The runaway process in a model pumped-storage system was simulated for analyzing the dynamic characteristics of a pump-turbine. The simulation was adopted by coupling 1D (One Dimensional) pipeline MOC (Method of Characteristics) equations with a 3D (Three Dimensional) pump-turbine CFD (Computational Fluid Dynamics) model, in which the water hammer wave in the 3D zone was defined by giving a pressure dependent density. We found from the results that the dynamic performances of the pump-turbine do not coincide with the static operating points, especially in the S-shaped characteristics region, where the dynamic trajectories follow ring-shaped curves. Specifically, the transient operating points with the same Q11 and M11 in different moving directions of the dynamic trajectories give different n11. The main reason of this phenomenon is that the transient flow patterns inside the pump-turbine are influenced by the ones in the previous time step, which leads to different flow patterns between the points with the same Q11 and M11 in different moving directions of the dynamic trajectories.

  18. Dynamic control of a bistable wing under aerodynamic loading

    International Nuclear Information System (INIS)

    Bilgen, Onur; Arrieta, Andres F; Friswell, Michael I; Hagedorn, Peter

    2013-01-01

    The aerodynamic evaluation of a dynamic control technique applied to a bistable unsymmetrical cross-ply composite plate with surface bonded piezoelectric actuators is presented. The plate is clamped on one end to form a low-aspect-ratio wing. A previously proposed dynamic control method, utilizing bending resonance in different stable equilibrium positions, is used to induce snap-through between the two equilibrium states. Compared to quasi-static actuation, driving the bistable plate near resonance using surface bonded piezoelectric materials requires, theoretically, a lower peak excitation voltage to achieve snap-through. First, a set of extensive wind tunnel experiments are conducted on the passive bistable wing to understand the change in the dynamic behavior under various aerodynamic conditions. The passive wing demonstrated sufficient bending stiffness to sustain its shape under aerodynamic loading while preserving the desired bistable behavior. Next, by the use of the resonant control technique, the plate is turned into an effectively monostable structure, or alternatively, both stable equilibrium positions can be reached actively from the other stable equilibrium. Dynamic forward and reverse snap-through is demonstrated in the wind tunnel which shows both the effectiveness of the piezoelectric actuation as well as the load carrying capability of both states of the bistable wing. (paper)

  19. Loading technique for dynamic response studies of geological materials

    International Nuclear Information System (INIS)

    Butler, R.I.; Forrestal, M.J.

    1979-04-01

    A loading technique to study the dynamic response of tuff was explored. Loading is provided by electrically exploding etched copper mesh patterns with current from a capacitor discharge. Pressure pulses with peak pressures up to 1.25 kbar and 0.10 to 0.20 ms durations were measured with a pressure bar. The upper value of peak pressure was limited by the strength of the experimental apparatus, and higher pressure generation is possible with a redesign of test hardware. 6 figures, 2 tables

  20. Dynamic Response of Coarse Granular Material to Wave Load

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo

    1998-01-01

    The soil beneath vertical breakwaters is subjected to a combination of forces induced by the waves. The forces acting on the soil can be characterized as 1) static load due to submerged weight of the structure, 2) quasi-static forces induced by cyclic wave loading, and 3) wave impact from breaking...... waves. The stress conditions in the soil below a foundation exposed to these types of loading are very complex. The key to explain and quantify the soil response beneath a vertical breakwater is to understand the role of the volume changes and to be able to model these correctly. It is shown...... that the volume changes in soil subjected to static and dynamic loading are controlled by the characteristic line. Experiments have been performed to study the factors that influence the location of the characteristic line in drained and undrained tests for various types of sand and various types of loading...

  1. Dynamic stresses in a Francis model turbine at deep part load

    Science.gov (United States)

    Weber, Wilhelm; von Locquenghien, Florian; Conrad, Philipp; Koutnik, Jiri

    2017-04-01

    A comparison between numerically obtained dynamic stresses in a Francis model turbine at deep part load with experimental ones is presented. Due to the change in the electrical power mix to more content of new renewable energy sources, Francis turbines are forced to operate at deep part load in order to compensate stochastic nature of wind and solar power and to ensure grid stability. For the extension of the operating range towards deep part load improved understanding of the harsh flow conditions and their impact on material fatigue of hydraulic components is required in order to ensure long life time of the power unit. In this paper pressure loads on a model turbine runner from unsteady two-phase computational fluid dynamics simulation at deep part load are used for calculation of mechanical stresses by finite element analysis. Therewith, stress distribution over time is determined. Since only few runner rotations are simulated due to enormous numerical cost, more effort has to be spent to evaluation procedure in order to obtain objective results. By comparing the numerical results with measured strains accuracy of the whole simulation procedure is verified.

  2. Evaluation of muscle activity for loaded and unloaded dynamic squats during vertical whole-body vibration.

    Science.gov (United States)

    Hazell, Tom J; Kenno, Kenji A; Jakobi, Jennifer M

    2010-07-01

    The purpose of this investigation was to examine if the addition of a light external load would enhance whole-body vibration (WBV)-induced increases in muscle activity during dynamic squatting in 4 leg muscles. Thirteen recreationally active male university students performed a series of dynamic squats (unloaded with no WBV, unloaded with WBV, loaded with no WBV, and loaded with WBV). The load was set to 30% of body mass and WBV included 25-, 35-, and 45-Hz frequencies with 4-mm amplitude. Muscle activity was recorded with surface electromyography (EMG) on the vastus lateralis (VL), biceps femoris (BF), tibialis anterior (TA), and gastrocnemius (GC) and is reported as EMGrms (root mean square) normalized to %maximal voluntary exertion. During unloaded dynamic squats, exposure to WBV (45 Hz) significantly (p squat exercise in all muscles but decreased the TA. This loaded level of muscle activity was further increased with WBV (45 Hz) in all muscles. The WBV-induced increases in muscle activity in the loaded condition (approximately 3.5%) were of a similar magnitude to the WBV-induced increases during the unloaded condition (approximately 2.5%) demonstrating the addition of WBV to unloaded or loaded dynamic squatting results in an increase in muscle activity. These results demonstrate the potential effectiveness of using external loads with exposure to WBV.

  3. A technique for measuring dynamic friction coefficient under impact loading.

    Science.gov (United States)

    Lin, Y L; Qin, J G; Chen, R; Zhao, P D; Lu, F Y

    2014-09-01

    We develop a novel setup based on the split Hopkinson pressure bar technique to test the dynamic friction coefficient under impact loading. In the setup, the major improvement is that the end of the incident bar near the specimen is wedge-shaped, which results in a combined compressive and shear loading applied to the specimen. In fact, the shear loading is caused by the interfacial friction between specimen and bars. Therefore, when the two loading force histories are measured, the friction coefficient histories can be calculated without any assumptions and theoretical derivations. The geometry of the friction pairs is simple, and can be either cuboid or cylindrical. Regarding the measurements, two quartz transducers are used to directly record the force histories, and an optical apparatus is designed to test the interfacial slip movement. By using the setup, the dynamic friction coefficient of PTFE/aluminum 7075 friction pairs was tested. The time resolved dynamic friction coefficient and slip movement histories were achieved. The results show that the friction coefficient changes during the loading process, the average data of the relatively stable flat plateau section of the friction coefficient curves is 0.137, the maximum normal pressure is 52 MPa, the maximum relative slip velocity is 1.5 m/s, and the acceleration is 8400 m(2)/s. Furthermore, the friction test was simulated using an explicit FEM code LS-DYNA. The simulation results showed that the constant pressure and slip velocity can both be obtained with a wide flat plateau incident pulse. For some special friction pairs, normal pressure up to a few hundred MPa, interfacial slip velocities up to 10 m/s, and slip movement up to centimeter-level can be expected.

  4. Preliminary Study on Structural Optimization with Control Variables Using Equivalent Static Loads for Spring-damper Control Systems

    International Nuclear Information System (INIS)

    Yoo, Nam-sun; Jung, Ui-Jin; Park, Gyung-Jin; Kim, Tai-Kyung

    2014-01-01

    An optimization method is proposed for the simultaneous design of structural and control systems using the equivalent static loads. In the past researches, the control parameters of such feedback gains are obtained to improve some performance in the steady-state. However, the actuators which have position and velocity feedback gains should be designed to exhibit a good performance in the time domain. In other words, the system analysis should be conducted for the transient-state in dynamic manner. In this research, a new equivalent static loads method is presented to treat the control variables as the design variables. The equivalent static loads (ESLs) set is defined as a static load set which generates the same displacement field as that from dynamic loads at a certain time. The calculated sets of ESLs are applied as multiple loading conditions in the optimization process. Several examples are solved to validate the proposed method

  5. Response of porous beryllium to static and dynamic loading

    Energy Technology Data Exchange (ETDEWEB)

    Isbell, W.M.; Walton, O.R.; Ree, F.H.

    1977-07-01

    Previous investigstions of the mechanical response of porous materials to dynamic loading have been extended to include the shock wave response of a brittle metal. The complex response of berylliums of 85 to 90 percent porosity in two initial conditions has been examined in a theoretical and experimental program to be described. The study has resulted in the development of constitutive relations placed in hydrocodes which are capable of accurately predicting wave propagation in the berylliums. A comprehensive set of static (0 to 4 Gpa) and dynamic (0 to 35 Gpa) experiments was performed to measure the behavior of these brittle, porous materials to imposed loads. The results of the experiments guided a modeling effort which added several new features to previous models, including deviatoric stresses, porosity-dependent relaxation time of pore closure, elastic-plastic reopening of pores, and improved compaction functions.

  6. Response of porous beryllium to static and dynamic loading

    International Nuclear Information System (INIS)

    Isbell, W.M.; Walton, O.R.; Ree, F.H.

    1977-07-01

    Previous investigstions of the mechanical response of porous materials to dynamic loading have been extended to include the shock wave response of a brittle metal. The complex response of berylliums of 85 to 90 percent porosity in two initial conditions has been examined in a theoretical and experimental program to be described. The study has resulted in the development of constitutive relations placed in hydrocodes which are capable of accurately predicting wave propagation in the berylliums. A comprehensive set of static (0 to 4 Gpa) and dynamic (0 to 35 Gpa) experiments was performed to measure the behavior of these brittle, porous materials to imposed loads. The results of the experiments guided a modeling effort which added several new features to previous models, including deviatoric stresses, porosity-dependent relaxation time of pore closure, elastic-plastic reopening of pores, and improved compaction functions

  7. Transient dynamic and inelastic analysis of shells of revolution - a survey of programs

    International Nuclear Information System (INIS)

    Svalbonas, V.

    1976-01-01

    Advances in the limits of structural use in the aerospace and nuclear power industries over the past years have increased the requirements upon the applicable analytical computer programs to include accurate capabilities for inelastic and transient dynamic analyses. In many minds, however, this advanced capability is unequivocally linked with the large scale, general purpose, finite element programs. This idea is also combined with the view that such analyses are therefore prohibitively expensive and should be relegated to the 'last resort' classification. While this, in the general sense, may indeed be the case, if the user needs only to analyze structures falling into limited categories, however, he may find that a variety of smaller special purpose programs are available which do not put an undue strain upon his resources. One such structural category is shells of revolution. This survey of programs concentrates upon the analytical tools which have been developed predominantly for shells of revolution. The survey is subdivided into three parts: (a) consideration of programs for transient dynamic analysis; (b) consideration of programs for inelastic analysis and finally; (c) consideration of programs capable of dynamic plasticity analysis. In each part, programs based upon finite difference, finite element, and numerical integration methods are considered. The programs are compared on the basis of analytical capabilities, and ease of idealization and use. In each part of the survey sample problems are utilized to exemplify the state-of-the-art. (Auth.)

  8. A follow-up of transients. Stage 1

    International Nuclear Information System (INIS)

    Enekull, Aa.; Wallner, B.

    1981-09-01

    A follow-up of the transients of temperature and pressure in the primary pressurized system of a nuclear power plant has been completed for the Barsebaeck-1 reactor. The investigation consists of the following steps:- the collation of transients - drawing up load data based on transients-analyses of stress - recommendations for future programs. It was found that the lifetime of the system will exceed 40 years excluding some of the pipes for feed water. The appendices give a detailed description of the transients.(G.B.)

  9. Dynamic Analysis of Helical Planetary Gear Sets under Combined Force and Moment Loading

    Directory of Open Access Journals (Sweden)

    Yanfang Liu

    2017-01-01

    Full Text Available The dynamic behavior of a single-stage planetary gear set with helical gears of multishaft automotive automatic transmissions has been studied, in which one component of the planetary gear set is imposed by additional external vertical and axial loading from countershaft gear pair in addition to the moment. Under these combined loading conditions, the contributions of the deflections of the ring gear and the carrier cannot be neglected. A three-dimensional nonlinear time-variant dynamic model considering not only the transverse, torsional, axial, and rotational motions of the gears but also the elasticity of the mounted shafts has been developed by combining the lumped parameter method with finite element method. The natural modes and the forced vibration responses due to static transmission errors have been obtained. The proposed dynamic model is employed to describe the effects of the combined external loading condition and positioning on the dynamic behavior of a four-planet system.

  10. Dynamic analysis of elastic rubber tired car wheel breaking under variable normal load

    Science.gov (United States)

    Fedotov, A. I.; Zedgenizov, V. G.; Ovchinnikova, N. I.

    2017-10-01

    The purpose of the paper is to analyze the dynamics of the braking of the wheel under normal load variations. The paper uses a mathematical simulation method according to which the calculation model of an object as a mechanical system is associated with a dynamically equivalent schematic structure of the automatic control. Transfer function tool analyzing structural and technical characteristics of an object as well as force disturbances were used. It was proved that the analysis of dynamic characteristics of the wheel subjected to external force disturbances has to take into account amplitude and phase-frequency characteristics. Normal load variations impact car wheel braking subjected to disturbances. The closer slip to the critical point is, the higher the impact is. In the super-critical area, load variations cause fast wheel blocking.

  11. Structure and dynamics of paramagnetic transients by pulsed EPR and NMR detection of nuclear resonance. [Pulse radiolysis of methanol in D/sub 2/O

    Energy Technology Data Exchange (ETDEWEB)

    Trifunac, A.D.

    1981-01-01

    Structure and dynamics of transient radicals in pulse radiolysis can be studied by time resolved EPR and NMR techniques. EPR study of kinetics and relaxation is illustrated. The NMR detection of nuclear resonance in transient radicals is a new method which allows the study of hyperfine coupling, population dynamics, radical kinetics, and reaction mechanism. 9 figures.

  12. 46 CFR 154.409 - Dynamic loads from vessel motion.

    Science.gov (United States)

    2010-10-01

    ... in length and is an analysis by the following formulae that corresponds to a 10−8 probability level... EC02FE91.086 (d) If a cargo tank is designed to avoid fatigue, the dynamic loads determined under paragraph...

  13. Dynamic load-sharing characteristic analysis of face gear power-split gear system based on tooth contact characteristics

    Science.gov (United States)

    Dong, Hao; Hu, Yahui

    2018-04-01

    The bend-torsion coupling dynamics load-sharing model of the helicopter face gear split torque transmission system is established by using concentrated quality standard, to analyzing the dynamic load-sharing characteristic. The mathematical models include nonlinear support stiffness, time-varying meshing stiffness, damping, gear backlash. The results showed that the errors collectively influenced the load sharing characteristics, only reduce a certain error, it is never fully reached the perfect loading sharing characteristics. The system load-sharing performance can be improved through floating shaft support. The above-method will provide a theoretical basis and data support for its dynamic performance optimization design.

  14. An analytical model for the ductile failure of biaxially loaded type 316 stainless steel subjected to thermal transients

    International Nuclear Information System (INIS)

    Dimelfi, R.J.

    1987-01-01

    Failure properties are calculated for the case of biaxially loaded type 316 stainless steel tubes that are heated from 300 K to near melting at various constant rates. The procedure involves combining a steady state plastic-deformation rate law with a strain hardening equation. Integrating under the condition of plastic instability gives the time and plastic strain at which ductile failure occurs for a given load. The result is presented as an analytical expression for equivalent plastic strain as a function of equivalent stress, temperature, heating rate and material constants. At large initial load, ductile fracture is calculated to occur early, at low temperatures, after very little deformation. At very small loads deformation continues for a long time to high temperatures where creep rupture mechanisms limit ductility. In the case of intermediate loads, the plastic strain accumulated before the occurrence of unstable ductile fracture is calculated. Comparison of calculated results is made with existing experimental data from pressurized tubes heated at 5.6 K/s and 111 K/s. When the effect of grain growth on creep ductility is taken into account from recrystallization data, agreement between measured and calculated uniform ductility is excellent. The general reduction in ductility and failure time that is observed at higher heating rate is explained via the model. The model provides an analytical expression for the ductility and failure time during transients for biaxially loaded type 316 stainless steel as a function of the initial temperature and load, as well as the material creep and strain hardening parameters. (orig.)

  15. Calculation of piping loads due to filling procedures; Berechnung von Rohrleitungsbelastungen durch Fuellvorgaenge

    Energy Technology Data Exchange (ETDEWEB)

    Swidersky, Harald; Thiele, Thomas [TUeV Sued Industrie Service GmbH, Muenchen (Germany)

    2012-11-01

    Filling procedures in piping systems are usually not load cases that are studied by fluid dynamic and structure dynamic analyses with respect to the integrity of pipes and supports. Although, their frequency is higher than that of postulated accidental transients, therefore they have to be considered for fatigue analyses. The piping and support loads due to filling procedures are caused by the density differences if the transported fluids, for instance in flows with the transport of gas bubbles. The impact duration of the momentum forces is defined by the flow velocity and the length of discontinuities in the piping segments. Filling procedures end very often with a shock pressure, caused by the impact and decelerating of the fluid front at smaller cross sections. The suitability of the thermally hydraulics program RELAP/MOD3.3 for the calculation of realistic loads from filling procedures was studied, the results compared with experimental data. It is shown that dependent on the discretization level the loads are partial significantly underestimated.

  16. Self-organized dynamics in local load-sharing fiber bundle models.

    Science.gov (United States)

    Biswas, Soumyajyoti; Chakrabarti, Bikas K

    2013-10-01

    We study the dynamics of a local load-sharing fiber bundle model in two dimensions under an external load (which increases with time at a fixed slow rate) applied at a single point. Due to the local load-sharing nature, the redistributed load remains localized along the boundary of the broken patch. The system then goes to a self-organized state with a stationary average value of load per fiber along the (increasing) boundary of the broken patch (damaged region) and a scale-free distribution of avalanche sizes and other related quantities are observed. In particular, when the load redistribution is only among nearest surviving fiber(s), the numerical estimates of the exponent values are comparable with those of the Manna model. When the load redistribution is uniform along the patch boundary, the model shows a simple mean-field limit of this self-organizing critical behavior, for which we give analytical estimates of the saturation load per fiber values and avalanche size distribution exponent. These are in good agreement with numerical simulation results.

  17. Dynamic Response in Transient Stress-Field Behavior Induced by Hydraulic Fracturing

    Science.gov (United States)

    Jenkins, Andrew

    magnitude. These types of shifts are of great concern because they can impact subsequent fracture development causing non-uniform fracture propagation and the potential overlapping of fracture paths as they extend from the wellbore at the point of injection. The dynamics of stress variation that occur with respect to hydraulic fracturing is a somewhat new area of study. In order to accomplish the goals of this thesis and continue future research in this area a new transient model has been developed in order to asses these dynamic systems and determine their influence on fracture behavior. This applies the use of a fully coupled finite element method in 2-D using linear elastic fracture mechanics which is then expanded using displacement discontinuity to a cohesive zone model in 3-D. A static boundary element model was also used to determine stress fields surrounding static, predetermined fracture geometries. These models have been verified against analytical solutions for simple cases and are now being applied to more detailed case studies and analysis. These models have been briefly discussed throughout this thesis in order to give insight on their current capabilities and application as well as their future potential within this area of research. The majority of this work introduces transient stress field prediction to cases of single and multiple hydraulic fractures. The static assessment of these stresses is determined for verification of results to those found in publication which leads into these transient stress field variations. A new method has been developed and applied to the stress state prediction for the first time in a transient fracture model which is partly based upon a critical distance theory. These dynamic interactions can provide useful insight to pertinent issues within the petroleum and natural gas industry such as those to hydraulic fracturing fluid loss and induced seismic events, as well as to applications of efficiency and optimization of the

  18. A transient absorption study of allophycocyanin

    Indian Academy of Sciences (India)

    Transient dynamics of allophycocyanin trimers and monomers are observed by using the pump-probe, transient absorption technique. The origin of spectral components of the transient absorption spectra is discussed in terms of both kinetics and spectroscopy. We find that the energy gap between the ground and excited ...

  19. Long-term dynamic loading improves the mechanical properties of chondrogenic mesenchymal stem cell-laden hydrogel

    Directory of Open Access Journals (Sweden)

    AH Huang

    2010-02-01

    Full Text Available Mesenchymal stem cells (MSCs are an attractive cell source for cartilage tissue engineering given their ability to undergo chondrogenesis in 3D culture systems. Mechanical forces play an important role in regulating both cartilage development and MSC chondrogenic gene expression, however, mechanical stimulation has yet to enhance the mechanical properties of engineered constructs. In this study, we applied long-term dynamic compression to MSC-seeded constructs and assessed whether varying pre-culture duration, loading regimens and inclusion of TGF-beta3 during loading would influence functional outcomes and these phenotypic transitions. Loading initiated before chondrogenesis decreased functional maturation, although chondrogenic gene expression increased. In contrast, loading initiated after chondrogenesis and matrix elaboration further improved the mechanical properties of MSC-based constructs, but only when TGF-beta3 levels were maintained and under specific loading parameters. Although matrix quantity was not affected by dynamic compression, matrix distribution, assessed histologically and by FT-IRIS analysis, was significantly improved on the micro- (pericellular and macro- (construct expanse scales. Further, whole genome expression profiling revealed marked shifts in the molecular topography with dynamic loading. These results demonstrate, for the first time, that dynamic compressive loading initiated after a sufficient period of chondro-induction and with sustained TGF-beta exposure enhances matrix distribution and the mechanical properties of MSC-seeded constructs.

  20. Estimation of inelastic behavior for a tapered nozzle in vessel due to thermal transient load using stress redistribution locus method

    International Nuclear Information System (INIS)

    Kobayashi, Ken-ichi; Yamada, Jun-ichi

    2010-01-01

    Simplified inelastic design procedures for elevated temperature components have been required to reduce simulation cost and to shorten a period of time for developing new projects. Stress redistribution locus (SRL) method has been proposed to provide a reasonable estimate employing both the elastic FEM analysis and a unique hyperbolic curve: ε tilde={1/σ tilde + (κ - 1)σ tilde}/κ, where ε tilde and σ tilde show dimensionless strain and stress normalized by corresponding elastic ones, respectively. This method is based on a fact that stress distribution in well deformed or high temperature components would change with deformation or time, and that the relation between the dimensionless stress and strain traces a kind of the elastic follow-up locus in spite of the constitutive equation of material and loading modes. In this paper, FEM analyses incorporating plasticity and creep in were performed for a tapered nozzle in reactor vessel under some thermal transient loads through the nozzle thickness. The normalized stress and strain was compared with the proposed SRL curve. Calculation results revealed that a critical point in the tapered nozzle due to the thermal transient load depended on a descending rate of temperature from the higher temperature in the operation cycle. Since the inelastic behavior in the nozzle resulted in a restricted area, the relationship between the normalized stress and strain was depicted inside the proposed SRL curve: Coefficient κ of the SRL in analyses is greater than the proposed one, and the present criterion guarantees robust structures for complicated components involving inelastic deformation. (author)

  1. Dynamic Regression Intervention Modeling for the Malaysian Daily Load

    Directory of Open Access Journals (Sweden)

    Fadhilah Abdrazak

    2014-05-01

    Full Text Available Malaysia is a unique country due to having both fixed and moving holidays.  These moving holidays may overlap with other fixed holidays and therefore, increase the complexity of the load forecasting activities. The errors due to holidays’ effects in the load forecasting are known to be higher than other factors.  If these effects can be estimated and removed, the behavior of the series could be better viewed.  Thus, the aim of this paper is to improve the forecasting errors by using a dynamic regression model with intervention analysis.   Based on the linear transfer function method, a daily load model consists of either peak or average is developed.  The developed model outperformed the seasonal ARIMA model in estimating the fixed and moving holidays’ effects and achieved a smaller Mean Absolute Percentage Error (MAPE in load forecast.

  2. Ripple Mitigation with Improved Line-Load Transients Response in Two-Stage DC-DC-AC Converter

    DEFF Research Database (Denmark)

    Gautam, Aditya R.; Gaurav, Kumar; Guerrero, Josep M.

    2018-01-01

    . The front-end boost converter in the considered two-stage converter interfaces a battery bank and single phase inverter fed loads. The control shapes the output impedance of boost converter to reduce the ripple component at battery input. Secondly, the proposed controller achieves good dynamic performance...

  3. Winnerless competition principle and prediction of the transient dynamics in a Lotka-Volterra model

    Science.gov (United States)

    Afraimovich, Valentin; Tristan, Irma; Huerta, Ramon; Rabinovich, Mikhail I.

    2008-12-01

    Predicting the evolution of multispecies ecological systems is an intriguing problem. A sufficiently complex model with the necessary predicting power requires solutions that are structurally stable. Small variations of the system parameters should not qualitatively perturb its solutions. When one is interested in just asymptotic results of evolution (as time goes to infinity), then the problem has a straightforward mathematical image involving simple attractors (fixed points or limit cycles) of a dynamical system. However, for an accurate prediction of evolution, the analysis of transient solutions is critical. In this paper, in the framework of the traditional Lotka-Volterra model (generalized in some sense), we show that the transient solution representing multispecies sequential competition can be reproducible and predictable with high probability.

  4. The Comprehensive Biomechanics and Load-Sharing of Semirigid PEEK and Semirigid Posterior Dynamic Stabilization Systems

    Directory of Open Access Journals (Sweden)

    D. K. Sengupta

    2013-01-01

    Full Text Available Alternatives to conventional rigid fusion have been proposed for several conditions related to degenerative disc disease when nonoperative treatment has failed. Semirigid fixation, in the form of dynamic stabilization or PEEK rods, is expected to provide compression under loading as well as an intermediate level of stabilization. This study systematically examines both the load-sharing characteristics and kinematics of these two devices compared to the standard of internal rigid fixators. Load-sharing was studied by using digital pressure films inserted between an artificially machined disc and two loading fixtures. Rigid rods, PEEK rods, and the dynamic stabilization system were inserted posteriorly for stabilization. The kinematics were quantified on ten, human, cadaver lumbosacral spines (L3-S1 which were tested under a pure bending moment, in flexion-extension, lateral bending, and axial rotation. The magnitude of load transmission through the anterior column was significantly greater with the dynamic device compared to PEEK rods and rigid rods. The contact pressures were distributed more uniformly, throughout the disc with the dynamic stabilization devices, and had smaller maximum point-loading (pressures on any particular point within the disc. Kinematically, the motion was reduced by both semirigid devices similarly in all directions, with slight rigidity imparted by a lateral interbody device.

  5. Dynamic loading of galvanized parts

    Directory of Open Access Journals (Sweden)

    Michal Černý

    2010-01-01

    Full Text Available This work is divided into two parts: the theoretical part includes actual knowledge and points of view about degradation processes in construction materials, anticorrosion protection, zinc coat composition and high frequency fatigue. The laboratory part follow-up existing regulations contents Czech standards and formulate specifications for acquisition of objective information from acceleration la­bo­ra­to­ry tests in condensation chests, mechanical high frequency fatigue tests on pulsator machine and possibilities of evaluation of fatigue tests. Laboratory findings declare to fundamental types of damage of constructions with anticorrosion protection in real loading conditions with dynamic high frequency character. Laboratory tests were made in sulphide and chloride environments.

  6. Dynamic modeling of primary and secondary systems of IRIS reactor for transient analysis using SIMULINK

    International Nuclear Information System (INIS)

    Magalhaes, Mardson Alencar de Sa; Lira, Carlos Alberto Brayner de Oliveira; Silva, Mario Augusto Bezerra da

    2011-01-01

    The IRIS project has significantly advanced in the last few years in response to a demand for a new generation reactor, that could fulfill the essential requirements for a future nuclear power plant: better economics, safety-by-design, low proliferation risk and environmental sustainability. IRIS reactor is a integral type PWR in which all primary components are arranged inside the pressure vessel. This configuration involves important changes in relation to a conventional PWR. These changes require several studies to comply with the safe operational limits for the reactor. In this paper, a study has been conducted to develop a dynamic model (named MODIRIS) for transient analysis, implemented in the MATLAB'S software SIMULINK, allowing the analysis of IRIS behavior by considering the neutron point kinetics for power production. The methodology is based on generating a set of differential equations of neutronic and thermal-hydraulic balances which describes the dynamics of the primary circuit, as well as a set of differential equations describing the dynamics of secondary circuit. The equations and initialization parameters at full power were into the SIMULINK and the code was validated by the confrontation with RELAP simulations for a transient of feedwater reduction in the steam generators. (author)

  7. A dynamic-biased dual-loop-feedback CMOS LDO regulator with fast transient response

    International Nuclear Information System (INIS)

    Wang Han; Sun Maomao

    2014-01-01

    This paper presents a low-dropout regulator (LDO) for portable applications with dual-loop feedback and a dynamic bias circuit. The dual-loop feedback structure is adopted to reduce the output voltage spike and the response time of the LDO. The dynamic bias circuit enhances the slew rate at the gate of the power transistor. In addition, an adaptive miller compensation technique is employed, from which a single pole system is realized and over a 59° phase margin is achieved under the full range of the load current. The proposed LDO has been implemented in a 0.6-μm CMOS process. From the experimental results, the regulator can operate with a minimum dropout voltage of 200 mV at a maximum 300 mA load and I Q of 113 μA. The line regulation and load regulation are improved to 0.1 mV/V and 3.4 μV/mA due to the sufficient loop gain provided by the dual feedback loops. Under a full range load current step, the voltage spikes and the recovery time of the proposed LDO is reduced to 97 mV and 0.142 μs respectively. (semiconductor integrated circuits)

  8. Fast relaxation transients in a kicked damped oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Urquizu, Merce [Laboratori d' Estudis Geofisics ' Eduard Fontsere' , IEC, Barcelona (Spain); Correig, Antoni M. [Departament d' Astronomical i Meteorologia, Laboratori d' Estudis Geofisics Eduard Fontsere, UB Marti Franques 1, E-08028 Barcelona (Spain) and Laboratori d' Estudis Geofisics ' Eduard Fontsere' , IEC, Barcelona (Spain)]. E-mail: ton.correig@am.ub.es

    2007-08-15

    Although nonlinear relaxation transients are very common in nature, very few studies are devoted to its characterization, mainly due to its short time duration. In this paper, we present a study about the nature of relaxation transients in a kicked damped oscillator, in which transients are generated in terms of continuous fast changes in the parameters of the system. We have found that transient dynamics can be described, rather than in terms of bifurcation dynamics, in terms of instantaneous stretching factors, which are related to the stability of fixed points of the corresponding stroboscopic maps.

  9. A design of cascade control system and adaptive load compensator for battery/ultracapacitor hybrid energy storage-based direct current microgrid

    International Nuclear Information System (INIS)

    Pavković, Danijel; Lobrović, Mihael; Hrgetić, Mario; Komljenović, Ante

    2016-01-01

    Highlights: • Battery/ultracapacitor storage is considered for a direct-current microgrid. • Microgrid voltage cascade control system with load compensator is designed. • Current references are allocated so that ultracapacitor takes on transient loads. • Adaptive Kalman filter-based estimator is used for indirect load compensation. • Control strategy has been verified on a downscaled hardware-in-the-loop setup. - Abstract: A control system design based on an actively-controlled battery/ultracapacitor hybrid energy storage system suitable for direct current microgrid energy management purposes is presented in this paper. The proposed cascade control system arrangement is based on the superimposed proportional–integral voltage controller designed according to Damping Optimum criterion and a zero-pole canceling feed-forward load compensator aimed at voltage excursion suppression under variable load conditions. The superimposed controller commands the inner battery and ultracapacitor current control loops through a dynamic current reference distribution scheme, wherein the ultracapacitor takes on the highly-dynamic (transient) current demands, and the battery covers for steady-state loads. In order to avoid deep discharges of the ultracapacitor module, it is equipped with an auxiliary state-of-charge controller. Finally, for those applications where load is not measured, an adaptive Kalman filter-based load compensator is proposed and tested. The presented control strategy has been implemented on the low-cost industrial controller unit, and its effectiveness has been verified by means of simulations and experiments for the cases of abrupt load changes and quasi-stochastic load profiles using a downscaled battery/ultracapacitor hardware-in-the-loop experimental setup.

  10. Transient dynamics in cavity electromagnetically induced transparency with ion Coulomb crystals

    Science.gov (United States)

    Albert, Magnus; Dantan, Aurélien; Drewsen, Michael

    2018-03-01

    We experimentally investigate the transient dynamics of an optical cavity field interacting with large ion Coulomb crystals in a situation of electromagnetically induced transparency (EIT). EIT is achieved by injecting a probe field at the single photon level and a more intense control field with opposite circular polarization into the same mode of an optical cavity to couple Zeeman substates of a metastable level in ? ions. The EIT interaction dynamics are investigated both in the frequency-domain - by measuring the probe field steady state reflectivity spectrum - and in the time-domain - by measuring the progressive buildup of transparency. The experimental results are observed to be in excellent agreement with theoretical predictions taking into account the inhomogeneity of the control field in the interaction volume, and confirm the high degree of control on light-matter interaction that can be achieved with ion Coulomb crystals in optical cavities.

  11. Dynamic simulation of a circulating fluidized bed boiler system part I: Description of the dynamic system and transient behavior of sub-models

    International Nuclear Information System (INIS)

    Kim, Seong Il; Choi, Sang Min; Yang, Jong In

    2016-01-01

    Dynamic performance simulation of a CFB boiler in a commercial-scale power plant is reported. The boiler system was modeled by a finite number of heat exchanger units, which are sub-grouped into the gas-solid circulation loop, the water-steam circulation loop, and the inter-connected heat exchangers blocks of the boiler. This dynamic model is an extension from the previously reported performance simulation model, which was designed to simulate static performance of the same power plant, where heat and mass for each of the heat exchanger units were balanced for the inter-connected heat exchanger network among the fuel combustion system and the water-steam system. Dynamic performance simulation was achieved by calculating the incremental difference from the previous time step, and progressing for the next time step. Additional discretization of the heat exchanger blocks was necessary to accommodate the dynamic response of the water evaporation and natural circulation as well as the transient response of the metal temperature of the heat exchanger elements. Presentation of the simulation modeling is organized into two parts; system configuration of the model plant and the general approach of the simulation are presented along with the transient behavior of the sub-models in Part I. Dynamic sub-models were integrated in terms of the mass flow and the heat transfer for simulating the CFB boiler system. Dynamic simulation for the open loop response was performed to check the integrated system of the water-steam loop and the solid-gas loop of the total boiler system. Simulation of the total boiler system which includes the closed-loop control system blocks is presented in the following Part II

  12. Dynamic simulation of a circulating fluidized bed boiler system part I: Description of the dynamic system and transient behavior of sub-models

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seong Il; Choi, Sang Min; Yang, Jong In [Dept. of Mechanical Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2016-12-15

    Dynamic performance simulation of a CFB boiler in a commercial-scale power plant is reported. The boiler system was modeled by a finite number of heat exchanger units, which are sub-grouped into the gas-solid circulation loop, the water-steam circulation loop, and the inter-connected heat exchangers blocks of the boiler. This dynamic model is an extension from the previously reported performance simulation model, which was designed to simulate static performance of the same power plant, where heat and mass for each of the heat exchanger units were balanced for the inter-connected heat exchanger network among the fuel combustion system and the water-steam system. Dynamic performance simulation was achieved by calculating the incremental difference from the previous time step, and progressing for the next time step. Additional discretization of the heat exchanger blocks was necessary to accommodate the dynamic response of the water evaporation and natural circulation as well as the transient response of the metal temperature of the heat exchanger elements. Presentation of the simulation modeling is organized into two parts; system configuration of the model plant and the general approach of the simulation are presented along with the transient behavior of the sub-models in Part I. Dynamic sub-models were integrated in terms of the mass flow and the heat transfer for simulating the CFB boiler system. Dynamic simulation for the open loop response was performed to check the integrated system of the water-steam loop and the solid-gas loop of the total boiler system. Simulation of the total boiler system which includes the closed-loop control system blocks is presented in the following Part II.

  13. Evolution of transiently melt damaged tungsten under ITER-relevant divertor plasma heat loading

    Energy Technology Data Exchange (ETDEWEB)

    Bardin, S., E-mail: s.bardin@differ.nl [FOM Institute DIFFER – Dutch Institute For Fundamental Energy Research, Ass EURATOM-FOM, Trilateral Euregio Cluster, Nieuwegein (Netherlands); Morgan, T.W. [FOM Institute DIFFER – Dutch Institute For Fundamental Energy Research, Ass EURATOM-FOM, Trilateral Euregio Cluster, Nieuwegein (Netherlands); Glad, X. [Université de Lorraine, Institut Jean Lamour, Vandoeuvre-les-Nancy (France); Pitts, R.A. [ITER Organization, CS 90 046, 13067 St Paul Lez Durance Cedex (France); De Temmerman, G. [FOM Institute DIFFER – Dutch Institute For Fundamental Energy Research, Ass EURATOM-FOM, Trilateral Euregio Cluster, Nieuwegein (Netherlands); ITER Organization, CS 90 046, 13067 St Paul Lez Durance Cedex (France)

    2015-08-15

    A high-repetition-rate ELM simulation system was used at both the Pilot-PSI and Magnum-PSI linear plasma devices to investigate the nature of W damage under multiple shallow melt events and the subsequent surface evolution under ITER relevant plasma fluence and high ELM number. First, repetitive shallow melting of two W monoblocks separated by a 0.5 mm gap was obtained by combined pulsed/steady-state hydrogen plasma loading at normal incidence in the Pilot-PSI device. Surface modifications including melting, cracking and strong net-reshaping of the surface are obtained. During the second step, the pre-damaged W sample was exposed to a high flux plasma regime in the Magnum-PSI device with a grazing angle of 35°. SEM analysis indicates no measurable change to the surface state after the exposure in Magnum-PSI. An increase in transient-induced temperature rise of 40% is however observed, indicating a degradation of thermal properties over time.

  14. Transient Performance Improvement Circuit (TPIC)s for DC-DC converter applications

    Science.gov (United States)

    Lim, Sungkeun

    Gordon Moore famously predicted the exponential increase in transistor integration and computing power that has been witnessed in recent decades [1]. In the near future, it is expected that more than one billion transistors will be integrated per chip, and advanced microprocessors will require clock speeds in excess of several GHz. The increasing number of transistors and high clock speeds will necessitate the consumption of more power. By 2014, it is expected that the maximum power consumption of the microprocessor will reach approximately 150W, and the maximum load current will be around 150A. Today's trend in power and thermal management is to reduce supply voltage as low as possible to reduce delivered power. It is anticipated that the Intel cores will operate on 0.8V of supply voltage by 2014 [2]. A significant challenge in Voltage Regulator Module (VRM) development for next generation microprocessors is to regulate the supply voltage within a certain tolerance band during high slew rate load transitions, since the required supply voltage tolerance band will be much narrower than the current requirement. If VR output impedance is maintained at a constant value from DC to high frequency, large output voltage spikes can be avoided during load cur- rent transients. Based on this, the Adaptive Voltage Position (AVP) concept was developed to achieve constant VR output impedance to improve transient response performance [3]. However, the VR output impedance can not be made constant over the entire frequency range with AVP design, because the AVP design makes the VR output impedance constant only at low frequencies. To make the output impedance constant at high frequencies, many bulk capacitors and ceramic capacitors are required. The tight supply voltage tolerance for the next generation of microprocessors during high slew rate load transitions requires fast transient response power supplies. A VRM can not follow the high slew rate load current transients, because

  15. Simulating transient dynamics of the time-dependent time fractional Fokker-Planck systems

    Science.gov (United States)

    Kang, Yan-Mei

    2016-09-01

    For a physically realistic type of time-dependent time fractional Fokker-Planck (FP) equation, derived as the continuous limit of the continuous time random walk with time-modulated Boltzmann jumping weight, a semi-analytic iteration scheme based on the truncated (generalized) Fourier series is presented to simulate the resultant transient dynamics when the external time modulation is a piece-wise constant signal. At first, the iteration scheme is demonstrated with a simple time-dependent time fractional FP equation on finite interval with two absorbing boundaries, and then it is generalized to the more general time-dependent Smoluchowski-type time fractional Fokker-Planck equation. The numerical examples verify the efficiency and accuracy of the iteration method, and some novel dynamical phenomena including polarized motion orientations and periodic response death are discussed.

  16. The Influence of External Load on Quadriceps Muscle and Tendon Dynamics during Jumping.

    Science.gov (United States)

    Earp, Jacob E; Newton, Robert U; Cormie, Prue; Blazevich, Anthony J

    2017-11-01

    Tendons possess both viscous (rate-dependent) and elastic (rate-independent) properties that determine tendon function. During high-speed movements external loading increases both the magnitude (FT) and rate (RFDT) of tendon loading. The influence of external loading on muscle and tendon dynamics during maximal vertical jumping was explored. Ten resistance-trained men performed parallel-depth, countermovement vertical jumps with and without additional load (0%, 30%, 60%, and 90% of maximum squat lift strength), while joint kinetics and kinematics, quadriceps tendon length (LT) and patellar tendon FT and RFDT were estimated using integrated ultrasound, motion analysis and force platform data and muscle tendon modelling. Estimated FT and RFDT, but not peak LT, increased with external loading. Temporal comparisons between 0% and 90% loads revealed that FT was greater with 90% loading throughout the majority of the movement (11%-81% and 87%-95% movement duration). However, RFDT was greater with 90% load only during the early movement initiation phase (8%-15% movement duration) but was greater in the 0% load condition later in the eccentric phase (27%-38% movement duration). LT was longer during the early movement (12%-23% movement duration) but shorter in the late eccentric and early concentric phases (48%-55% movement duration) with 90% load. External loading positively influenced peak FT and RFDT but tendon strain appeared unaffected, suggesting no additive effect of external loading on patellar tendon lengthening during human jumping. Temporal analysis revealed that external loading resulted in a large initial RFDT that may have caused dynamic stiffening of the tendon and attenuated tendon strain throughout the movement. These results suggest that external loading influences tendon lengthening in both a load- and movement-dependent manner.

  17. Transient eddy feedback and low-frequency variability

    International Nuclear Information System (INIS)

    Robinson, W.A.

    1994-01-01

    Superposed on any externally driven secular climatic change are fluctuations that arise from the internal nonlinear dynamics of the climate system. These internally generated variations may involve interactions between the atmosphere and the ocean, as in the case of El Nino, or they may arise from the dynamics of the atmosphere alone. Here we discuss the dynamics of interactions between transient eddies and lower-frequency motions in the atmosphere. The interactions between more transient and more persistent motions can be divided into two types. Nonlinear interactions among the transient motions can act as an essentially random source of low-frequency motion. The idea that the low-frequencies respond in a linear way to stochastic forcing from higher frequencies has been applied to the generation of planetary waves and to the forcing of changes in global angular momentum. In addition to stochastic coupling, there are systematic interactions, denoted feedbacks, through which the persistent motions modulate their own forcing by the transient eddies. This paper discusses the dynamics of these feedbacks

  18. Quality of computerized blast load simulation for non-linear dynamic ...

    African Journals Online (AJOL)

    Quality of computerized blast load simulation for non-linear dynamic response ... commercial software system and a special-purpose, blast-specific software product to ... depend both on the analysis model of choice and the stand-off distances.

  19. Loading dynamics of a sliding DNA clamp.

    KAUST Repository

    Cho, Won-Ki

    2014-05-22

    Sliding DNA clamps are loaded at a ss/dsDNA junction by a clamp loader that depends on ATP binding for clamp opening. Sequential ATP hydrolysis results in closure of the clamp so that it completely encircles and diffuses on dsDNA. We followed events during loading of an E. coli β clamp in real time by using single-molecule FRET (smFRET). Three successive FRET states were retained for 0.3 s, 0.7 s, and 9 min: Hydrolysis of the first ATP molecule by the γ clamp loader resulted in closure of the clamp in 0.3 s, and after 0.7 s in the closed conformation, the clamp was released to diffuse on the dsDNA for at least 9 min. An additional single-molecule polarization study revealed that the interfacial domain of the clamp rotated in plane by approximately 8° during clamp closure. The single-molecule polarization and FRET studies thus revealed the real-time dynamics of the ATP-hydrolysis-dependent 3D conformational change of the β clamp during loading at a ss/dsDNA junction.

  20. Transient analyzer

    International Nuclear Information System (INIS)

    Muir, M.D.

    1975-01-01

    The design and design philosophy of a high performance, extremely versatile transient analyzer is described. This sub-system was designed to be controlled through the data acquisition computer system which allows hands off operation. Thus it may be placed on the experiment side of the high voltage safety break between the experimental device and the control room. This analyzer provides control features which are extremely useful for data acquisition from PPPL diagnostics. These include dynamic sample rate changing, which may be intermixed with multiple post trigger operations with variable length blocks using normal, peak to peak or integrate modes. Included in the discussion are general remarks on the advantages of adding intelligence to transient analyzers, a detailed description of the characteristics of the PPPL transient analyzer, a description of the hardware, firmware, control language and operation of the PPPL transient analyzer, and general remarks on future trends in this type of instrumentation both at PPPL and in general

  1. Transient magnetoviscosity of dilute ferrofluids

    International Nuclear Information System (INIS)

    Soto-Aquino, Denisse; Rinaldi, Carlos

    2011-01-01

    The magnetic field induced change in the viscosity of a ferrofluid, commonly known as the magnetoviscous effect and parameterized through the magnetoviscosity, is one of the most interesting and practically relevant aspects of ferrofluid phenomena. Although the steady state behavior of ferrofluids under conditions of applied constant magnetic fields has received considerable attention, comparatively little attention has been given to the transient response of the magnetoviscosity to changes in the applied magnetic field or rate of shear deformation. Such transient response can provide further insight into the dynamics of ferrofluids and find practical application in the design of devices that take advantage of the magnetoviscous effect and inevitably must deal with changes in the applied magnetic field and deformation. In this contribution Brownian dynamics simulations and a simple model based on the ferrohydrodynamics equations are applied to explore the dependence of the transient magnetoviscosity for two cases: (I) a ferrofluid in a constant shear flow wherein the magnetic field is suddenly turned on, and (II) a ferrofluid in a constant magnetic field wherein the shear flow is suddenly started. Both simulations and analysis show that the transient approach to a steady state magnetoviscosity can be either monotonic or oscillatory depending on the relative magnitudes of the applied magnetic field and shear rate. - Research Highlights: →Rotational Brownian dynamics simulations were used to study the transient behavior of the magnetoviscosity of ferrofluids. →Damped and oscillatory approach to steady state magnetoviscosity was observed for step changes in shear rate and magnetic field. →A model based on the ferrohydrodynamics equations qualitatively captured the damped and oscillatory features of the transient response →The transient behavior is due to the interplay of hydrodynamic, magnetic, and Brownian torques on the suspended particles.

  2. Dynamics of gas-phase transient species studied by dissociative photodetachment of molecular anions

    OpenAIRE

    Lu, Zhou

    2007-01-01

    Gas-phase transient species, such as the CH₃CO₂ and HOCO free radicals, play important roles in combustion and environment chemistry. In this thesis work, the dynamics of these two radicals were studied by dissociative photodetachment (DPD) of the negative ions, CH₃CO₂-С and HOCO⁻, respectively. The experiments were carried out with a fast-ion-beam photoelectron-photofragment coincidence (PPC) spectrometer. Mass-selected molecular anions in a fast ion beam were intercepted by a linearly polar...

  3. Variation of Pore Water Pressure in Tailing Sand under Dynamic Loading

    Directory of Open Access Journals (Sweden)

    Jia-xu Jin

    2018-01-01

    Full Text Available Intense vibration affects the pore water pressure in a tailing dam, with the tendency to induce dam liquefaction. In this study, experiments were performed wherein model tailing dams were completely liquefied by sustained horizontal dynamic loading to determine the effects of the vibration frequency, vibration amplitude, and tailing density on the pore water pressure. The results revealed four stages in the increase of the tailing pore water pressure under dynamic loading, namely, a slow increase, a rapid increase, inducement of structural failure, and inducement of complete liquefaction. A lower frequency and smaller amplitude of the vibration were found to increase the time required to achieve a given pore water pressure in dense tailings. Under the effect of these three factors—vibration frequency and amplitude and tailing density—the tailing liquefaction time varied nonlinearly with the height from the base of the tailing dam, with an initial decrease followed by an increase. The pore pressure that induced structural failure also gradually decreased with increasing height. The increase in the tailing pore pressure could be described by an S-shaped model. A complementary multivariate nonlinear equation was also derived for predicting the tailing pore water pressure under dynamic loading.

  4. An investigation of loads generated by temperature transients in pipes

    International Nuclear Information System (INIS)

    Maneschy, C.E.

    1988-12-01

    An analysis is presented of the effect of a transient temperature on the stress distribution due to a fluid flowing through a pipe, is analytically determined using the definition of a variable called in this paper as ''shifted time''. This variable, which is related to the axial coordinate, the average fluid velocity and the real time, is defined to make the transient thermal problem one-dimensional. The stresses are then calculated from the temperature solution using the linear theory of viscoelasticity. (author) [pt

  5. Analysis of Dynamic Properties of Piezoelectric Structure under Impact Load

    Directory of Open Access Journals (Sweden)

    Taotao Zhang

    2015-10-01

    Full Text Available An analytical model of the dynamic properties is established for a piezoelectric structure under impact load, without considering noise and perturbations in this paper. Based on the general theory of piezo-elasticity and impact mechanics, the theoretical solutions of the mechanical and electrical fields of the smart structure are obtained with the standing and traveling wave methods, respectively. The comparisons between the two methods have shown that the standing wave method is better for studying long-time response after an impact load. In addition, good agreements are found between the theoretical and the numerical results. To simulate the impact load, both triangle and step pulse loads are used and comparisons are given. Furthermore, the influence of several parameters is discussed so as to provide some advices for practical use. It can be seen that the proposed analytical model would benefit, to some extent, the design and application (especially the airport runway of the related smart devices by taking into account their impact load performance.

  6. Direct Time Domain Numerical Analysis of Transient Behavior of a VLFS during Unsteady External Loads in Wave Condition

    Directory of Open Access Journals (Sweden)

    Yong Cheng

    2014-01-01

    Full Text Available The transient response of the VLFS subjected to arbitrary external load is systematically investigated by a direct time domain modal expansion method, in which the BEM solutions based on time domain Kelvin sources are used for hydrodynamic forces. In the analysis, the time domain free-surface Green functions with sufficient accuracy are rapidly evaluated in finite water depth by the interpolation-tabulation method, and the boundary integral equation with a quarter VLFS model is established taking advantage of symmetry of flow field and structure. The validity of the present method is verified by comparing with the time histories of vertical displacements of the VLFS during a mass drop and airplane landing and takeoff in still water conditions, respectively. Then the developed numerical scheme is used in wave conditions to study the combined action taking into account the mass drop/airplane landing/takeoff loads as well as incident wave action. It is found that the elevation of structural waves due to mass drop load can be significantly changed near the impact region, while the vertical motion of runway in wave conditions is dominant as compared with that only generated by airplane.

  7. Dynamic supplier selection problem considering full truck load in probabilistic environment

    Science.gov (United States)

    Sutrisno, Wicaksono, Purnawan Adi

    2017-11-01

    In this paper, we propose a mathematical model in a probabilistic dynamic optimization to solve a dynamic supplier selection problem considering full truck load in probabilistic environment where some parameters are uncertain. We determine the optimal strategy for this problem by using stochastic dynamic programming. We give some numerical experiments to evaluate and analyze the model. From the results, the optimal supplier and the optimal product volume from the optimal supplier were determined for each time period.

  8. Ensuring dynamic load smoothness in problem of controlling Atomic Electric Power Stations exclusive mechanisms

    International Nuclear Information System (INIS)

    Shumilov, V.F.

    2003-01-01

    New methods for the investigation of automatic systems based on the inverse tasks of dynamics with the use of rational, trigonometric and polynomial spline functions are discussed. By means of SH function the technological regimes: start-up, steadiness, racing, braking, reverse, stop were determined. Procedure for the provision of dynamic load smoothness is suggested, and example of control over the transport systems for fuel load is considered [ru

  9. HOLD MODE BASED DYNAMIC PRIORITY LOAD ADAPTIVE INTERPICONET SCHEDULING FOR BLUETOOTH SCATTERNETS

    Directory of Open Access Journals (Sweden)

    G.S. Mahalakshmi

    2011-09-01

    Full Text Available Scheduling in piconets has emerged as a challenging research area. Interpiconet scheduling focuses on when a bridge is switched among various piconets and how a bridge node communicates with the masters in different piconets. This paper proposes an interpiconet scheduling algorithm named, hold mode based dynamic traffic priority load adaptive scheduling. The bridges are adaptively switched between the piconets according to various traffic loads. The main goal is to maximize the utilization of the bridge by reducing the bridge switch wastes, utilize intelligent decision making algorithm, resolve conflict between the masters, and allow negotiation for bridge utilization in HDPLIS using bridge failure-bridge repair procedure . The Hold mode - dynamic traffic - priority based - load adaptive scheduling reduces the number of bridge switch wastes and hence increases the efficiency of the bridge which results in increased performance of the system.

  10. Vibration of functionally graded plate resting on viscoelastic elastic foundation subjected to moving loads

    Science.gov (United States)

    Duy Hien, Ta; Lam, Nguyen Ngoc

    2018-04-01

    The dynamics of plates subjected to a moving load must be considered by engineering mechanics and design structures. This paper deals with the dynamic responses of functionally graded (FG) rectangular plates resting on a viscoelastic foundation under moving loads. It is assumed that material properties of the plate vary continuously in the thickness direction according to the power-law. The governing equations are derived by using Hamilton’s principle, which considers the effect of the higher-order shear deformation in the plate. Transient responses of simply supported FG rectangular plates are employed by using state-space methods. Several examples are given for displacement and stresses in the plates with various structural parameters, and the effects of these parameters are discussed.

  11. Transient stability analysis in electric power systems with frequency dependent loads; Analise de estabilidade transitoria em sistemas eletricos de potencia com cargas dependentes da frequencia

    Energy Technology Data Exchange (ETDEWEB)

    Alberto, Luis F. Costa; Borelli, Jose Renato; Bretas, Newton G. [Sao Paulo Univ., Sao Carlos, SP (Brazil). Dept. de Engenharia Eletrica

    1997-12-31

    The power system models normally used to transient stability analysis are very simplified. Damping effects such as frequency dependent loads are neglected. In order to incorporate these effects in the analysis, a frequency dependent load model is proposed, and it is shown the important influence that it causes in the critical clearing times for stability analysis beyond the first swing. this load model require the network structure preservation and the knowledge of frequency of non-generator buses. In this work, an efficient method to estimate the frequencies of non-generator buses was developed. (author) 11 refs., 5 figs., 2 tabs.; e-mail: ngbretas at sel.eesc.sc.usp.br

  12. PWR systems transient analysis

    International Nuclear Information System (INIS)

    Kennedy, M.F.; Peeler, G.B.; Abramson, P.B.

    1985-01-01

    Analysis of transients in pressurized water reactor (PWR) systems involves the assessment of the response of the total plant, including primary and secondary coolant systems, steam piping and turbine (possibly including the complete feedwater train), and various control and safety systems. Transient analysis is performed as part of the plant safety analysis to insure the adequacy of the reactor design and operating procedures and to verify the applicable plant emergency guidelines. Event sequences which must be examined are developed by considering possible failures or maloperations of plant components. These vary in severity (and calculational difficulty) from a series of normal operational transients, such as minor load changes, reactor trips, valve and pump malfunctions, up to the double-ended guillotine rupture of a primary reactor coolant system pipe known as a Large Break Loss of Coolant Accident (LBLOCA). The focus of this paper is the analysis of all those transients and accidents except loss of coolant accidents

  13. Dynamic load-balancing-extended gradient mechanism: Graphic representation

    International Nuclear Information System (INIS)

    Muniz, Francisco J.

    2017-01-01

    Load-balancing methods are quite well described in the open literature (hundreds of articles can be found about this subject). In particularly, about the Dynamic Load-balancing mechanism Extended Gradient (EG), several articles of the author are available. Even though, there are some overlap, each one of them is focused on a particular aspect of the mechanism, in a complementary way. In this article, a graphic representation of the Extended Gradient mechanism is done: this representation way had not yet been explored. However, for an in-depth knowledge of the Extended Gradient mechanism, at least, some other articles should to be read. In the CDTN, Clusters are used, mainly, in deterministic methods (CFD) and non-deterministic methods (Monte Carlo). (author)

  14. Dynamic load-balancing-extended gradient mechanism: Graphic representation

    Energy Technology Data Exchange (ETDEWEB)

    Muniz, Francisco J., E-mail: muniz@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2017-07-01

    Load-balancing methods are quite well described in the open literature (hundreds of articles can be found about this subject). In particularly, about the Dynamic Load-balancing mechanism Extended Gradient (EG), several articles of the author are available. Even though, there are some overlap, each one of them is focused on a particular aspect of the mechanism, in a complementary way. In this article, a graphic representation of the Extended Gradient mechanism is done: this representation way had not yet been explored. However, for an in-depth knowledge of the Extended Gradient mechanism, at least, some other articles should to be read. In the CDTN, Clusters are used, mainly, in deterministic methods (CFD) and non-deterministic methods (Monte Carlo). (author)

  15. Ductile Crack Initiation Criterion with Mismatched Weld Joints Under Dynamic Loading Conditions.

    Science.gov (United States)

    An, Gyubaek; Jeong, Se-Min; Park, Jeongung

    2018-03-01

    Brittle failure of high toughness steel structures tends to occur after ductile crack initiation/propagation. Damages to steel structures were reported in the Hanshin Great Earthquake. Several brittle failures were observed in beam-to-column connection zones with geometrical discontinuity. It is widely known that triaxial stresses accelerate the ductile fracture of steels. The study examined the effects of geometrical heterogeneity and strength mismatches (both of which elevate plastic constraints due to heterogeneous plastic straining) and loading rate on critical conditions initiating ductile fracture. This involved applying the two-parameter criterion (involving equivalent plastic strain and stress triaxiality) to estimate ductile cracking for strength mismatched specimens under static and dynamic tensile loading conditions. Ductile crack initiation testing was conducted under static and dynamic loading conditions using circumferentially notched specimens (Charpy type) with/without strength mismatches. The results indicated that the condition for ductile crack initiation using the two parameter criterion was a transferable criterion to evaluate ductile crack initiation independent of the existence of strength mismatches and loading rates.

  16. Transient electromagnetic and dynamic structural analyses of a blanket structure with coupling effects

    Energy Technology Data Exchange (ETDEWEB)

    Koganezawa, K. [Mitsubishi Atomic Power Industries, Inc., Yokohama (Japan); Kushiyama, M. [Mitsubishi Atomic Power Industries, Inc., Yokohama (Japan); Niikura, S. [Mitsubishi Atomic Power Industries, Inc., Yokohama (Japan); Kudough, F. [Mitsubishi Atomic Power Industries, Inc., Yokohama (Japan); Onozuka, M. [Mitsubishi Heavy Industries Ltd., Yokohama (Japan); Koizumi, K. [Japan Atomic Energy Research Inst., Ibaraki (Japan)

    1995-12-31

    Transient electromagnetic and dynamic structural analyses of a blanket structure in the fusion experimental reactor (FER) under a plasma disruption event and a vertical displacement event (VDE) have been performed to investigate the dynamic structural characteristics and the feasibility of the structure. Coupling effects between eddy currents and dynamic deflections have also been taken into account in these analyses. In this study, the inboard blanket was employed because of our computer memory limitation. A 1/192 segment model of a full torus was analyzed using the analytical code, EDDYCUFF. In the plasma disruption event, the maximum magnetic pressure caused by eddy currents and poloidal fields was 1.2MPa. The maximum stress intensity by this magnetic pressure was 114MPa. In the VDE, the maximum magnetic pressure was 2.4MPa and the maximum stress intensity was 253MPa. This stress was somewhat beyond the allowable stress limit. Therefore, the blanket structure and support design should be reviewed to reduce the stress to a suitable value. In summary, the dynamic structural characteristics and design issues of the blanket structure have been identified. (orig.).

  17. Merenje prelaznih opterećenja na dva modela u aero tunelu t-38 / Measurement of transient loads on two models

    Directory of Open Access Journals (Sweden)

    Aleksandar Vitić

    2008-07-01

    Full Text Available Pri ispitivanju modela u "rafalnom" aerotunelu sa prekidnim dejstvom T-38, na Mahovim brojevima većim od 2, moraju se uzeti u obzir prelazne pojave koje se javljaju na početku i na kraju rada aerotunela. To su stanja kada su model i aerovaga izloženi velikim aerodinamičkim silama i momentima. Ova kombinovana opterećenja mogu oštetiti modele i aerovage, pa bi bilo potrebno unapred znati kolike se vrednosti očekuju za pojedine konfiguracije modela, kako bi se izvršio pravilan izbor aerovage i odgovarajućih materijala za izradu modela. U tu svrhu postoje dijagrami koji pružaju mogućnost procene ovih opterećenja. Dijagrami su dobijeni na osnovu ispitivanja nekoliko različitih modela na Mahovim brojevima većim od 2. U radu su prikazana merenja prelaznih opterećenja na još dva modela, a rezultati su upoređeni sa već postojećim dijagramima. / The T-38 wind tunnel is a blow down, intermittent-run type of wind tunnels. During model testing in the this type of wind tunnels, at Mach numbers higher than 2, transient loads which appear during the starting and stopping of the wind tunnel runs must be taken into consideration. These are the conditions when a model and the wind tunnel balance are exposed to large aerodynamic forces and moments. These combined loads can damage models and wind tunnel balances, and, for this reason, it is very important to determine them in advance for any particular model configuration so that an appropriate wind tunnel balance and materials for model manufacturing can be chosen. For that purpose there are graphs which give possibilities to estimate these loads. The graphs are based on experiments with a number of different models at Mach numbers higher than 2. This paper gives the measurements of transient loads on two more models and the results are compared with the already existing graphs.

  18. Performance of various types of containment support under quasi-static and dynamic loading conditions, Part I.

    CSIR Research Space (South Africa)

    Kuijpers, JS

    2002-05-01

    Full Text Available deformations. In this project, the effects of dynamic loading are therefore specifically addressed. In order to monitor the effects of extreme dynamic loading conditions on various tunnel support systems, a real scale physical model has been used... systems and allow the identification of shortcomings and potential improvements. A conceptual, analytical model representing the load deformation behaviour of strings (lacing and mesh) has been developed. This model does allow for a quantification...

  19. Power System Transient Stability Improvement Using Demand Side Management in Competitive Electricity Markets

    DEFF Research Database (Denmark)

    Hu, Weihao; Wang, Chunqi; Chen, Zhe

    2012-01-01

    Since the hourly spot market price is available one day ahead in Denmark, the price could be transferred to the consumers and they may shift some of their loads from high price periods to the low price periods in order to save their energy costs. The optimal load response to an electricity price...... for demand side management generates different load profiles and may provide an opportunity to improve the transient stability of power systems with high wind power penetrations. In this paper, the idea of the power system transient stability improvement by using optimal load response to the electricity...... price is proposed. A 102-bus power system which represents a simplified model of the western Danish power system is chosen as the study case. Simulation results show that the optimal load response to electricity prices is an effective measure to improve the power system transient stability with high...

  20. Limitations and corrections in measuring dynamic characteristics of structural systems

    International Nuclear Information System (INIS)

    Walter, P.L.

    1978-10-01

    The work deals with limitations encountered in measuring the dynamic characteristics of structural systems. Structural loading and response are measured by transducers possessing multiple resonant frequencies in their transfer function. In transient environments, the resultant signals from these transducers are shown to be analytically unpredictable in amplitude level and frequency content. Data recorded during nuclear effects simulation testing on structures are analyzed. Results of analysis can be generalized to any structure which encounters dynamic loading. Methods to improve the recorded data are described which can be implemented on a frequency selective basis during the measurement process. These improvements minimize data distortion attributable to the transfer characteristics of the measuring transducers

  1. Exploring the temporal dynamics of sustained and transient spatial attention using steady-state visual evoked potentials.

    Science.gov (United States)

    Zhang, Dan; Hong, Bo; Gao, Shangkai; Röder, Brigitte

    2017-05-01

    While the behavioral dynamics as well as the functional network of sustained and transient attention have extensively been studied, their underlying neural mechanisms have most often been investigated in separate experiments. In the present study, participants were instructed to perform an audio-visual spatial attention task. They were asked to attend to either the left or the right hemifield and to respond to deviant transient either auditory or visual stimuli. Steady-state visual evoked potentials (SSVEPs) elicited by two task irrelevant pattern reversing checkerboards flickering at 10 and 15 Hz in the left and the right hemifields, respectively, were used to continuously monitor the locus of spatial attention. The amplitude and phase of the SSVEPs were extracted for single trials and were separately analyzed. Sustained attention to one hemifield (spatial attention) as well as to the auditory modality (intermodal attention) increased the inter-trial phase locking of the SSVEP responses, whereas briefly presented visual and auditory stimuli decreased the single-trial SSVEP amplitude between 200 and 500 ms post-stimulus. This transient change of the single-trial amplitude was restricted to the SSVEPs elicited by the reversing checkerboard in the spatially attended hemifield and thus might reflect a transient re-orienting of attention towards the brief stimuli. Thus, the present results demonstrate independent, but interacting neural mechanisms of sustained and transient attentional orienting.

  2. Optimization of structures subjected to dynamic load: deterministic and probabilistic methods

    Directory of Open Access Journals (Sweden)

    Élcio Cassimiro Alves

    Full Text Available Abstract This paper deals with the deterministic and probabilistic optimization of structures against bending when submitted to dynamic loads. The deterministic optimization problem considers the plate submitted to a time varying load while the probabilistic one takes into account a random loading defined by a power spectral density function. The correlation between the two problems is made by one Fourier Transformed. The finite element method is used to model the structures. The sensitivity analysis is performed through the analytical method and the optimization problem is dealt with by the method of interior points. A comparison between the deterministic optimisation and the probabilistic one with a power spectral density function compatible with the time varying load shows very good results.

  3. Analysis of Spontaneous and Nerve-Evoked Calcium Transients in Intact Extraocular Muscles in Vitro

    Science.gov (United States)

    Feng, Cheng-Yuan; Hennig, Grant W.; Corrigan, Robert D.; Smith, Terence K.; von Bartheld, Christopher S.

    2012-01-01

    Extraocular muscles (EOMs) have unique calcium handling properties, yet little is known about the dynamics of calcium events underlying ultrafast and tonic contractions in myofibers of intact EOMs. Superior oblique EOMs of juvenile chickens were dissected with their nerve attached, maintained in oxygenated Krebs buffer, and loaded with fluo-4. Spontaneous and nerve stimulation-evoked calcium transients were recorded and, following calcium imaging, some EOMs were double-labeled with rhodamine-conjugated alpha-bungarotoxin (rhBTX) to identify EOM myofiber types. EOMs showed two main types of spontaneous calcium transients, one slow type (calcium waves with 1/2max duration of 2–12 s, velocity of 25–50 μm/s) and two fast “flash-like” types (Type 1, 30–90 ms; Type 2, 90–150 ms 1/2max duration). Single pulse nerve stimulation evoked fast calcium transients identical to the fast (Type 1) calcium transients. Calcium waves were accompanied by a local myofiber contraction that followed the calcium transient wavefront. The magnitude of calcium-wave induced myofiber contraction far exceeded those of movement induced by nerve stimulation and associated fast calcium transients. Tetrodotoxin eliminated nerve-evoked transients, but not spontaneous transients. Alpha-bungarotoxin eliminated both spontaneous and nerve-evoked fast calcium transients, but not calcium waves, and caffeine increased wave activity. Calcium waves were observed in myofibers lacking spontaneous or evoked fast transients, suggestive of multiply-innervated myofibers, and this was confirmed by double-labeling with rhBTX. We propose that the abundant spontaneous calcium transients and calcium waves with localized contractions that do not depend on innervation may contribute to intrinsic generation of tonic functions of EOMs. PMID:22579493

  4. Dynamic characterization and modeling of magneto-rheological elastomers under compressive loadings

    International Nuclear Information System (INIS)

    Koo, J H; Khan, F; Jang, D D; Jung, H J

    2009-01-01

    The primary goal of this paper is to characterize and model the compression properties of Magneto-Rheological Elastomers (MREs). MRE samples were fabricated by curing a two component elastomer resin with 30% content of 10 μm sized iron particles by volume. In order to vary the magnetic field during compressive testing, a test fixture was designed and fabricated in which two permanent magnets could be variably positioned on either side of the specimen. By changing the distance between the magnets, the fixture allowed for varying the magnetic field that passes uniformly through the sample. Using this test setup and a dynamic test frame, a series of compression tests of MRE samples was performed by varying the magnetic field and frequency of loading. The results show the MR effect (percent increase in the materials 'stiffness') increases as the magnetic field increases and loading frequency increases within the range of the magnetic field and input frequency considered in this study. Furthermore, a phenomenological model was developed to capture the dynamic behaviours of the MREs under compression loadings.

  5. Response of Jupiter's Aurora to Plasma Mass Loading Rate Monitored by the Hisaki Satellite During Volcanic Eruptions at Io

    Science.gov (United States)

    Kimura, T.; Hiraki, Y.; Tao, C.; Tsuchiya, F.; Delamere, P. A.; Yoshioka, K.; Murakami, G.; Yamazaki, A.; Kita, H.; Badman, S. V.; Fukazawa, K.; Yoshikawa, I.; Fujimoto, M.

    2018-03-01

    The production and transport of plasma mass are essential processes in the dynamics of planetary magnetospheres. At Jupiter, it is hypothesized that Io's volcanic plasma carried out of the plasma torus is transported radially outward in the rotating magnetosphere and is recurrently ejected as plasmoid via tail reconnection. The plasmoid ejection is likely associated with particle energization, radial plasma flow, and transient auroral emissions. However, it has not been demonstrated that plasmoid ejection is sensitive to mass loading because of the lack of simultaneous observations of both processes. We report the response of plasmoid ejection to mass loading during large volcanic eruptions at Io in 2015. Response of the transient aurora to the mass loading rate was investigated based on a combination of Hisaki satellite monitoring and a newly developed analytic model. We found that the transient aurora frequently recurred at a 2-6 day period in response to a mass loading increase from 0.3 to 0.5 t/s. In general, the recurrence of the transient aurora was not significantly correlated with the solar wind, although there was an exceptional event with a maximum emission power of 10 TW after the solar wind shock arrival. The recurrence of plasmoid ejection requires the precondition that an amount comparable to the total mass of magnetosphere, 1.5 Mt, is accumulated in the magnetosphere. A plasmoid mass of more than 0.1 Mt is necessary in case that the plasmoid ejection is the only process for mass release.

  6. Substantiation of strength of TVSA-ALPHA fuel assembly under dynamic seismic loads

    International Nuclear Information System (INIS)

    Tutnov, A.; Kiselev, A.; Kiselev, A.; Krutko, E.; Kiselev, I.; Samoilov, O.; Kaydalov, V.

    2009-01-01

    A special place in the substantiation of the safe operation of fuel assemblies is the assessment their operating capability under seismic loads, leading to short-term (several seconds or tens of seconds) the dynamic effects on the reactor core. The level of acceleration of various elements of the reactor installation can be higher than 1,5 g (g - acceleration of gravity) and depends on the height of these elements relatively the ground, which movement causes an earthquake. This dynamic load cause significant deformation of the active zones design element, in particular of the fuel assemblies (FA), which could lead to a contact (or impact) interaction between them. The report presents the results of studies of stress-strain state of FA of TVSA-ALPHA type under the influence of seismic loads of the 8th level on Richter scale using standard approach. According to a normative approach the natural frequencies and modes of FA are calculated in the preliminary stage. The obtained results are conservative from the point of view that in the real FA design the most loaded SG in the middle of the fuel assemblies are made in a combined with mixing grid variant, which are joint by a common rim. This increases the overall carrying capacity of SG as compared with the calculation SG model. It is also necessary to bear in mind that the dynamic (impact) loading the basic mechanical properties of the material may have a significant difference from static (standard) values. This refers in particular to the yield limit, the value of which can be several times higher than specified in the calculation

  7. Rambling and trembling in response to body loading.

    Science.gov (United States)

    Tahayor, Behdad; Riley, Zachary A; Mahmoudian, Armaghan; Koceja, David M; Hong, Siang Lee

    2012-04-01

    Various studies have suggested that postural sway is controlled by at least two subsystems. Rambling-Trembling analysis is a widely accepted methodology to dissociate the signals generated by these two hypothetical subsystems. The core assumption of this method is based on the equilibrium point hypothesis which suggests that the central nervous system preserves upright standing by transiently shifting the center of pressure (COP) from one equilibrium point to another. The trajectory generated by this shifting is referred to as rambling and its difference from the original COP signal is referred to as trembling. In this study we showed that these two components of COP are differentially affected when standing with external loads. Using Detrended Fluctuation analysis, we compared the pattern of these two signals in different configurations of body loading. Our findings suggest that by applying an external load, the dynamics of the trembling component is altered independently of the area of postural sway and also independently of the rambling component. The dynamics of rambling changed only during the backloading condition in which the postural sway area also substantially increased. It can be suggested that during loaded standing, the trembling mechanism (which is suggested to be activated by peripheral mechanisms and reflexes) is altered without affecting the central influence on the shifts of the equilibrium point.

  8. Transients and burn dynamics in advanced tokamak fusion reactors

    International Nuclear Information System (INIS)

    Mantsinen, M.J.; Salomaa, R.R.E.

    1994-01-01

    Transient behavior of D 3 He-tokamak reactors is investigated numerically using a zero-dimensional code with prescribed profiles. Pure D 3 He start-up is compared to DT-assisted and DT-ignited start-ups. We have considered two categories of transients which could extinguish steady fusion burn: fuelling interruptions and sudden confinement changes similar to the L → H transients occurring in present-day tokamaks. Shutdown with various current and density ramp-down scenarios are studied, too. (author)

  9. Comprehensive Structural Dynamic Analysis of the SSME/AT Fuel Pump First-Stage Turbine Blade

    Science.gov (United States)

    Brown, A. M.

    1998-01-01

    A detailed structural dynamic analysis of the Pratt & Whitney high-pressure fuel pump first-stage turbine blades has been performed to identify the cause of the tip cracking found in the turbomachinery in November 1997. The analysis was also used to help evaluate potential fixes for the problem. Many of the methods available in structural dynamics were applied, including modal displacement and stress analysis, frequency and transient response to tip loading from the first-stage Blade Outer Gas Seals (BOGS), fourier analysis, and shock spectra analysis of the transient response. The primary findings were that the BOGS tip loading is impulsive in nature, thereby exciting many modes of the blade that exhibit high stress at the tip cracking location. Therefore, a proposed BOGS count change would not help the situation because a clearly identifiable resonance situation does not exist. The recommendations for the resolution of the problem are to maintain the existing BOGS count, eliminate the stress concentration in the blade due to its geometric design, and reduce the applied load on the blade by adding shiplaps in the BOGS.

  10. Research of thermal dynamic characteristics for variable load single screw refrigeration compressor with different capacity control mechanism

    International Nuclear Information System (INIS)

    Wang, Zengli; Wang, Zhenbo; Wang, Jun; Jiang, Wenchun; Feng, Quanke

    2017-01-01

    Highlights: • Theoretical models of SSRC under part-load condition have been established. • The experiment of SSRC performance under part-load condition was conducted. • Thermal dynamic characteristic of SSRC under part-load condition was gained. • Economy and reliability of SSRC under part-load condition was analyzed. - Abstract: In the single screw refrigeration compressor (SSRC), the capacity control mechanism is normally employed to meet the actual required cooling capacity under different load conditions. In this paper, theoretical calculation models describing the working process of the SSRC with the single slide valve capacity control mechanism (SVCCM) and SSRC with the frequency conversion regulating mechanism (FCRM) are established to research the thermal dynamic characteristics for variable load SSRC under part-load conditions. Experimental investigation on a SSRC under part-load conditions is also carried out to verify the theoretical calculation models. By using these validated models, the thermodynamic performances and dynamic characteristics of the SSRC with different capacity control mechanism under part-load conditions have been analyzed and compared. Through the comparison, the economical efficiency and reliability of the SSRC with different capacity control mechanism were obtained. All of these works can provide the basis for the later optimization design for the variable load single screw refrigeration compressor.

  11. Pulse mitigation and heat transfer enhancement techniques. Volume 3: Liquid sodium heat transfer facility and transient response of sodium heat pipe to pulse forward and reverse heat load

    Science.gov (United States)

    Chow, L. C.; Hahn, O. J.; Nguyen, H. X.

    1992-08-01

    This report presents the description of a liquid sodium heat transfer facility (sodium loop) constructed to support the study of transient response of heat pipes. The facility, consisting of the loop itself, a safety system, and a data acquisition system, can be safely operated over a wide range of temperature and sodium flow rate. The transient response of a heat pipe to pulse heat load at the condenser section was experimentally investigated. A 0.457 m screen wick, sodium heat pipe with an outer diameter of 0.127 m was tested under different heat loading conditions. A major finding was that the heat pipe reversed under a pulse heat load applied at the condenser. The time of reversal was approximately 15 to 25 seconds. The startup of the heat pipe from frozen state was also studied. It was found that during the startup process, at least part of the heat pipe was active. The active region extended gradually down to the end of the condenser until all of the working fluid in the heat pipe was molten.

  12. Nanosecond UV lasers stimulate transient Ca2+ elevations in human hNT astrocytes.

    Science.gov (United States)

    Raos, B J; Graham, E S; Unsworth, C P

    2017-06-01

    Astrocytes respond to various stimuli resulting in intracellular Ca 2+ signals that can propagate through organized functional networks. Recent literature calls for the development of techniques that can stimulate astrocytes in a fast and highly localized manner to emulate more closely the characteristics of astrocytic Ca 2+ signals in vivo. In this article we demonstrate, for the first time, how nanosecond UV lasers are capable of reproducibly stimulating Ca 2+ transients in human hNT astrocytes. We report that laser pulses with a beam energy of 4-29 µJ generate transient increases in cytosolic Ca 2+ . These Ca 2+ transients then propagate to adjacent astrocytes as intercellular Ca 2+ waves. We propose that nanosecond laser stimulation provides a valuable tool for enabling the study of Ca 2+ dynamics in human astrocytes at both a single cell and network level. Compared to previously developed techniques nanosecond laser stimulation has the advantage of not requiring loading of photo-caged or -sensitising agents, is non-contact, enables stimulation with a high spatiotemporal resolution and is comparatively cost effective.

  13. A Reduced-Order Model for Evaluating the Dynamic Response of Multilayer Plates to Impulsive Loads

    Science.gov (United States)

    2016-04-12

    A REDUCED-ORDER MODEL FOR EVALUATING THE DYNAMIC RESPONSE OF MULTILAYER PLATES TO IMPULSIVE LOADS Weiran Jiang, Alyssa Bennett, Nickolas...innovative multilayer materials or structures to optimize the dynamic performance as a mechanism to absorb and spread energy from an impulsive load...models. • Optimizing the structural weight and levels of protection of the multilayer plates with a good combination of materials. Technical Approach 2016

  14. Transient stress control of aeroengine disks based on active thermal management

    International Nuclear Information System (INIS)

    Ding, Shuiting; Wang, Ziyao; Li, Guo; Liu, Chuankai; Yang, Liu

    2016-01-01

    Highlights: • The essence of cooling in turbine system is a process of thermal management. • Active thermal management is proposed to control transient stress of disks. • The correlation between thermal load and transient stress of disks is built. • Stress level can be declined by actively adjusting the thermal load distribution. • Artificial temperature gradient can be used to counteract stress from rotating. - Abstract: The physical essence of cooling in the turbine system is a process of thermal management. In order to overcome the limits of passive thermal management based on thermal protection, the concept of active thermal management based on thermal load redistribution has been proposed. On this basis, this paper focuses on a near real aeroengine disk during a transient process and studies the stress control mechanism of active thermal management in transient conditions by a semi-analytical method. Active thermal management is conducted by imposing extra heating energy on the disk hub, which is represented by the coefficient of extra heat flow η. The results show that the transient stress level can be effectively controlled by actively adjusting the thermal load distribution. The decline ratio of the peak equivalent stress of the disk hub can be 9.0% for active thermal management load condition (η = 0.2) compared with passive condition (η = 0), even at a rotation speed of 10,000 r/min. The reason may be that the temperature distribution of the disk turns into an artificial V-shape because of the extra heating energy on the hub, and the resulting thermal stresses induced by the negative temperature gradients counteract parts of the stress from rotating.

  15. Mathematical Model and Computational Analysis of Selected Transient States of Cylindrical Linear Induction Motor Fed via Frequency Converter

    Directory of Open Access Journals (Sweden)

    Andrzej Rusek

    2008-01-01

    Full Text Available The mathematical model of cylindrical linear induction motor (C-LIM fed via frequency converter is presented in the paper. The model was developed in order to analyze numerically the transient states. Problems concerning dynamics of ac-machines especially linear induction motor are presented in [1 – 7]. Development of C-LIM mathematical model is based on circuit method and analogy to rotary induction motor. The analogy between both: (a stator and rotor windings of rotary induction motor and (b winding of primary part of C-LIM (inductor and closed current circuits in external secondary part of C-LIM (race is taken into consideration. The equations of C-LIM mathematical model are presented as matrix together with equations expressing each vector separately. A computational analysis of selected transient states of C-LIM fed via frequency converter is presented in the paper. Two typical examples of C-LIM operation are considered for the analysis: (a starting the motor at various static loads and various synchronous velocities and (b reverse of the motor at the same operation conditions. Results of simulation are presented as transient responses including transient electromagnetic force, transient linear velocity and transient phase current.

  16. TRANSIENT ANALYSIS OF WIND DIESEL POWER SYSTEM WITH FLYWHEEL ENERGY STORAGE

    Directory of Open Access Journals (Sweden)

    S. SUJITH

    2017-10-01

    Full Text Available Wind-Diesel Hybrid power generation is a viable alternative for generating continuous power to isolated power system areas which have inconsistent but potential wind power. The unpredictable nature of variable power from Wind generator to the system is compensated by Diesel generator, which supplies the deficit in generated power from wind to meet the instantaneous system load. However, one of the major challenges for such a system is the higher probability of transients in the form of wind and load fluctuations. This paper analyses the application of Flywheel Energy storage system (FESS to meet the transients during wind-speed and load fluctuations around high wind operation. The power system architecture, the distributed control mechanism governing the flow of power transfer and the modelling of major system components has been discussed and the system performances have been validated using MATLAB /Simulink software. Two cases of transient stages around the high wind system operation are discussed. The simulation results highlight the effective usage of FESS in reducing the peak overshoot of active power transients, smoothes the active power curves and helps in reducing the diesel consumption during the flywheel discharge period, without affecting the continuous power supply for meeting the instantaneous load demand.

  17. Understanding Epileptiform After-Discharges as Rhythmic Oscillatory Transients.

    Science.gov (United States)

    Baier, Gerold; Taylor, Peter N; Wang, Yujiang

    2017-01-01

    Electro-cortical activity in patients with epilepsy may show abnormal rhythmic transients in response to stimulation. Even when using the same stimulation parameters in the same patient, wide variability in the duration of transient response has been reported. These transients have long been considered important for the mapping of the excitability levels in the epileptic brain but their dynamic mechanism is still not well understood. To investigate the occurrence of abnormal transients dynamically, we use a thalamo-cortical neural population model of epileptic spike-wave activity and study the interaction between slow and fast subsystems. In a reduced version of the thalamo-cortical model, slow wave oscillations arise from a fold of cycles (FoC) bifurcation. This marks the onset of a region of bistability between a high amplitude oscillatory rhythm and the background state. In vicinity of the bistability in parameter space, the model has excitable dynamics, showing prolonged rhythmic transients in response to suprathreshold pulse stimulation. We analyse the state space geometry of the bistable and excitable states, and find that the rhythmic transient arises when the impending FoC bifurcation deforms the state space and creates an area of locally reduced attraction to the fixed point. This area essentially allows trajectories to dwell there before escaping to the stable steady state, thus creating rhythmic transients. In the full thalamo-cortical model, we find a similar FoC bifurcation structure. Based on the analysis, we propose an explanation of why stimulation induced epileptiform activity may vary between trials, and predict how the variability could be related to ongoing oscillatory background activity. We compare our dynamic mechanism with other mechanisms (such as a slow parameter change) to generate excitable transients, and we discuss the proposed excitability mechanism in the context of stimulation responses in the epileptic cortex.

  18. A new transiently chaotic flow with ellipsoid equilibria

    Science.gov (United States)

    Panahi, Shirin; Aram, Zainab; Jafari, Sajad; Pham, Viet-Thanh; Volos, Christos; Rajagopal, Karthikeyan

    2018-03-01

    In this article, a simple autonomous transiently chaotic flow with cubic nonlinearities is proposed. This system represents some unusual features such as having a surface of equilibria. We shall describe some dynamical properties and behaviours of this system in terms of eigenvalue structures, bifurcation diagrams, time series, and phase portraits. Various behaviours of this system such as periodic and transiently chaotic dynamics can be shown by setting special parameters in proper values. Our system belongs to a newly introduced category of transiently chaotic systems: systems with hidden attractors. Transiently chaotic behaviour of our proposed system has been implemented and tested by the OrCAD-PSpise software. We have found a proper qualitative similarity between circuit and simulation results.

  19. Synchronizing noisy nonidentical oscillators by transient uncoupling

    Energy Technology Data Exchange (ETDEWEB)

    Tandon, Aditya, E-mail: adityat@iitk.ac.in; Mannattil, Manu, E-mail: mmanu@iitk.ac.in [Department of Physics, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016 (India); Schröder, Malte, E-mail: malte@nld.ds.mpg.de [Network Dynamics, Max Planck Institute for Dynamics and Self-Organization (MPIDS), 37077 Göttingen (Germany); Timme, Marc, E-mail: timme@nld.ds.mpg.de [Network Dynamics, Max Planck Institute for Dynamics and Self-Organization (MPIDS), 37077 Göttingen (Germany); Department of Physics, Technical University of Darmstadt, 64289 Darmstadt (Germany); Chakraborty, Sagar, E-mail: sagarc@iitk.ac.in [Department of Physics, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016 (India); Mechanics and Applied Mathematics Group, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016 (India)

    2016-09-15

    Synchronization is the process of achieving identical dynamics among coupled identical units. If the units are different from each other, their dynamics cannot become identical; yet, after transients, there may emerge a functional relationship between them—a phenomenon termed “generalized synchronization.” Here, we show that the concept of transient uncoupling, recently introduced for synchronizing identical units, also supports generalized synchronization among nonidentical chaotic units. Generalized synchronization can be achieved by transient uncoupling even when it is impossible by regular coupling. We furthermore demonstrate that transient uncoupling stabilizes synchronization in the presence of common noise. Transient uncoupling works best if the units stay uncoupled whenever the driven orbit visits regions that are locally diverging in its phase space. Thus, to select a favorable uncoupling region, we propose an intuitive method that measures the local divergence at the phase points of the driven unit's trajectory by linearizing the flow and subsequently suppresses the divergence by uncoupling.

  20. Unified picture of the photoexcitations in phenylene-based conjugated polymers: Universal spectral and dynamical features in subpicosecond transient absorption

    International Nuclear Information System (INIS)

    Kraabel, B.; Klimov, V. I.; Kohlman, R.; Xu, S.; Wang, H-L.; McBranch, D. W.

    2000-01-01

    Using subpicosecond transient absorption spectroscopy, we investigate the primary photoexcitations in thin films and solutions of several phenylene-based conjugated polymers and an oligomer. We identify several features in the transient absorption spectra and dynamics that are common to all of the materials which we studied from this family. The first spectral feature is a photoinduced absorption (PA) band peaking near 1 eV that has intensity-dependent dynamics that match the stimulated emission dynamics exactly over two orders of magnitude in excitation density. This band is associated with singlet intrachain excitons. The second spectral feature (observed only in thin films and aggregated solutions) is a PA band peaking near 1.8 eV, that is longer lived than the 1 eV exciton PA band, and that has dynamics that are independent (or weakly dependent) on excitation density. This feature is attributed to polarons, generated through a mechanism that is sample dependent. In pristine samples, polarons are generated via a mechanism that is quadratic in exciton density, whereas in photodegraded samples or samples doped with electron acceptors, the generation mechanism becomes linear in exciton density. (c) 2000 The American Physical Society

  1. STAMINA OF A GASKETED BOLTED FLANGED PIPE JOINT UNDER DYNAMIC LOADING

    Directory of Open Access Journals (Sweden)

    Muhammad Abid

    2016-11-01

    Full Text Available Gasketed bolted flange joints are the most critical components in pipelines for their sealing and strength under operating conditions. Most of the work available in literature is under static loading, whereas in industry, cyclic loads are applied due to the vibrating machinery such as motors, pumps, sloshing in offshore applications and in the ships etc. In this study a three dimensional finite element analysis of a gasketed joint is carried out using a spiral wound gasket under bolt up and dynamic operating conditions (internal pressure, axial and bending singly and in combination. The cyclic axial loads are concluded relatively more challenging for both the sealing and strength of the joint. Higher magnitudes of loads and frequencies are also observed more challenging to the joints performance.

  2. Development of a simulation platform for dynamic simulation and control studies of AP1000 nuclear steam supply system

    International Nuclear Information System (INIS)

    Wan, Jiashuang; Song, Hongbing; Yan, Shoujun; Sun, Jian; Zhao, Fuyu

    2015-01-01

    Highlights: • A fast-running simulation platform named NCAP was developed on a personal computer using MATLAB/Simulink. • Three types of typical operations, namely 10% step load change, 5%/min ramp load change and load follow were simulated. • NCAP predictions were compared with those obtained by CENTS for the load regulation transients. - Abstract: This paper presents the development, application and performance assessment of a fast-running NCAP (NSSS Control & Analysis Platform) in MATLAB/Simulink environment. First, a nodal core model, a lumped parameter dynamic steam generator model with moving boundary, a non-equilibrium two-regions-three-volumes pressurizer model, and the relevant pipe and plenum models were proposed based on the fundamental conservation of mass, energy and momentum. Then, these first order nonlinear models and the NSSS control systems were implemented in the Simulink by the predefined library blocks. Based on the developed NCAP, three types of typical operational transients, namely the 10% step load change, the 5%/min ramp load change and the daily load follow were simulated to study the dynamic behavior and control characteristics of the AP1000 NSSS. It has been demonstrated that the dynamic responses of the selected key parameters agree well with the general physical rules. In addition, the comparison of load regulation simulation results obtained by NCAP and CENTS shows a good agreement in terms of the changing trends. With the adoption of modular programming techniques, the NCAP facilitates easy modification and runs quickly, which easily allows the control system designer to test and compare various ideas efficiently

  3. Mitigation method of thermal transient stress by thermalhydraulic-structure total analysis

    International Nuclear Information System (INIS)

    Kasahara, Naoto; Jinbo, Masakazu; Hosogai, Hiromi

    2003-01-01

    This study proposes a rational evaluation and mitigation method of thermal transient loads in fast reactor components by utilizing relationships among plant system parameters and stresses induced by thermal transients of plants. A thermalhydraulic-structure total analysis procedure helps us to grasp relationship among system parameters and thermal stresses. Furthermore, it enables mitigation of thermal transient loads by adjusting system parameters. In order to overcome huge computations, a thermalhydraulic-structure total analysis code and the Design of Experiments methodology are utilized. The efficiency of the proposed mitigation method is validated through thermal stress evaluation of an intermediate heat exchanger in Japanese demonstration fast reactor. (author)

  4. Transient selection in multicellular immune networks

    Science.gov (United States)

    Ivanchenko, M. V.

    2011-03-01

    We analyze the dynamics of a multi-clonotype naive T-cell population competing for survival signals from antigen-presenting cells. We find that this competition provides with an efficacious selection of clonotypes, making the less able and more repetitive get extinct. We uncover the scaling principles for large systems the extinction rate obeys and calibrate the model parameters to their experimental counterparts. For the first time, we estimate the physiological values of the T-cell receptor-antigen presentation profile recognition probability and T-cell clonotypes niche overlap. We demonstrate that, while the ultimate state is a stable fixed point, sequential transients dominate the dynamics over large timescales that may span over years, if not decades, in real time. We argue that what is currently viewed as "homeostasis" is a complex sequential transient process, while being quasi-stationary in the total number of T-cells only. The discovered type of sequential transient dynamics in large random networks is a novel alternative to the stable heteroclinic channel mechanism.

  5. Shear zone nucleation and deformation transient: effect of heterogeneities and loading conditions in experimentally deformed calcite

    Science.gov (United States)

    Morales, L. F. G.; Rybacki, E.; Dresen, G. H.; Kilian, R.

    2015-12-01

    In the Earth's middle to lower crust, strain is frequently localized along ductile shear zones, which commonly nucleate at structural and material heterogeneities. To investigate shear zone nucleation and development due to heterogeneities, we performed constant strain-rate (CSR) and constant stress (CS) simple shear (torsion) deformation experiments on Carrara marble samples containing weak (limestone) inclusions. The experiments were conducted in a Paterson-type gas deformation apparatus at 900 °C temperature and 400 MPa confining pressure and maximum bulk shear strains of 3. Peak shear stress was about 20 MPa for all the samples, followed by smooth weakening and steady state behavior. The strain is predominantly localized in the host marble within the process zone in front of the inclusion, defined by a zone of intense grain size reduction due to dynamic recrystallization. In CS tests a narrow shear zone developed in front of the inclusion, whereas in CSR experiments the deformation is more heterogeneously distributed, up to g=3.. In the later, secondary foliations oblique to the process zone and alternating thin, high-strain layers are common. In samples deformed at the same shear strain (g=1), the average recrystallized grain size in the process zone is similar for CS and CSR conditions. Crystallographic preferred orientation (CPO) measurements shows that different grain sizes have slightly different CPO patterns. CPO strength varies for different grain sizes, with a CPO strength peak between 40-50 μm, decreasing progressively within smaller grain size, but with secondary peaks for different coarse-grained sizes. Our observations suggest that the initial formation and transient deformation of shear zones is strongly affected by loading conditions.

  6. Strain-rate effect on initial crush stress of irregular honeycomb under dynamic loading and its deformation mechanism

    Science.gov (United States)

    Wang, Peng; Zheng, Zhijun; Liao, Shenfei; Yu, Jilin

    2018-02-01

    The seemingly contradictory understandings of the initial crush stress of cellular materials under dynamic loadings exist in the literature, and a comprehensive analysis of this issue is carried out with using direct information of local stress and strain. Local stress/strain calculation methods are applied to determine the initial crush stresses and the strain rates at initial crush from a cell-based finite element model of irregular honeycomb under dynamic loadings. The initial crush stress under constant-velocity compression is identical to the quasi-static one, but less than the one under direct impact, i.e. the initial crush stresses under different dynamic loadings could be very different even though there is no strain-rate effect of matrix material. A power-law relation between the initial crush stress and the strain rate is explored to describe the strain-rate effect on the initial crush stress of irregular honeycomb when the local strain rate exceeds a critical value, below which there is no strain-rate effect of irregular honeycomb. Deformation mechanisms of the initial crush behavior under dynamic loadings are also explored. The deformation modes of the initial crush region in the front of plastic compaction wave are different under different dynamic loadings.

  7. Experimental study of combustion noise radiation during transient turbocharged diesel engine operation

    International Nuclear Information System (INIS)

    Giakoumis, Evangelos G.; Dimaratos, Athanasios M.; Rakopoulos, Constantine D.

    2011-01-01

    Diesel engine noise radiation has drawn increased attention in recent years since it is associated with the passengers' and pedestrians' discomfort, a fact that has been acknowledged by the manufacturers and the legislation in many countries. In the current study, experimental tests were conducted on a truck, turbocharged diesel engine in order to investigate the mechanism of combustion noise emission under various transient schedules experienced during daily driving conditions, namely acceleration and load increase. To this aim, a fully instrumented test bed was set up in order to capture the development of key engine and turbocharger variables during the transient events. Analytical diagrams are provided to explain the behavior of combustion noise radiation in conjunction with cylinder pressure (spectrum), turbocharger and governor/fuel pump response. Turbocharger lag was found to be the main cause for the noise spikes during all test cases examined, with the engine injection timing calibration and the slow adjustment of cylinder wall temperature to the new fueling conditions playing a vital role. The analysis was extended with a quasi-steady approximation of transient combustion noise using steady-state maps, in order to better highlight the effect of dynamic engine operation on combustion noise emissions. -- Highlights: → Studying the effects of acceleration and load increase on the combustion noise radiation from a turbocharged diesel engine. → Turbocharger lag was the most notable contributor for the behavior of combustion noise radiation. → Turbocharged diesel engine behaves noisier at acceleration compared with the steady-state operation. → Fuel limiter, governing and engine injection timing calibration play a decisive role on the emission of combustion noise. → Transient noise radiation was smoothed the slower the acceleration and the smaller the demanded speed increase.

  8. Vortex-induced dynamic loads on a non-spinning volleyball

    Science.gov (United States)

    Qing-ding, Wei; Rong-sheng, Lin; Zhi-jie, Liu

    1988-09-01

    An experiment on vortex-induced dynamic loads on a non-spinning Volleyball was conducted in a wind tunnel. The flow past the Volleyball was visualized, and the aerodynamic load was measured by use of a strain gauge balance. The separation on the Volleyball was measured with hot-film. The experimental results suggest that under the action of an unstable tail vortex system the separation region is changeable, and that the fluctuation of drag and lateral forces is the same order of magnitude as the mean drag, no matter whether the seam of the Volleyball is symmetric or asymmetric, with regard to the flow. Based on the experimental data a numerical simulation of Volleyball swerve motion was made.

  9. Solar Dynamic Power System Stability Analysis and Control

    Science.gov (United States)

    Momoh, James A.; Wang, Yanchun

    1996-01-01

    The objective of this research is to conduct dynamic analysis, control design, and control performance test of solar power system. Solar power system consists of generation system and distribution network system. A bench mark system is used in this research, which includes a generator with excitation system and governor, an ac/dc converter, six DDCU's and forty-eight loads. A detailed model is used for modeling generator. Excitation system is represented by a third order model. DDCU is represented by a seventh order system. The load is modeled by the combination of constant power and constant impedance. Eigen-analysis and eigen-sensitivity analysis are used for system dynamic analysis. The effects of excitation system, governor, ac/dc converter control, and the type of load on system stability are discussed. In order to improve system transient stability, nonlinear ac/dc converter control is introduced. The direct linearization method is used for control design. The dynamic analysis results show that these controls affect system stability in different ways. The parameter coordination of controllers are recommended based on the dynamic analysis. It is concluded from the present studies that system stability is improved by the coordination of control parameters and the nonlinear ac/dc converter control stabilize system oscillation caused by the load change and system fault efficiently.

  10. Dynamic contrast-enhanced ultrasound and transient arterial occlusion for quantification of arterial perfusion reserve in peripheral arterial disease

    International Nuclear Information System (INIS)

    Amarteifio, E.; Wormsbecher, S.; Krix, M.; Demirel, S.; Braun, S.; Delorme, S.; Böckler, D.; Kauczor, H.-U.; Weber, M.-A.

    2012-01-01

    Objective: To quantify muscular micro-perfusion and arterial perfusion reserve in peripheral arterial disease (PAD) with dynamic contrast-enhanced ultrasound (CEUS) and transient arterial occlusion. Materials and methods: This study had local institutional review board approval and written informed consent was obtained from all subjects. We examined the dominant lower leg of 40 PAD Fontaine stage IIb patients (mean age, 65 years) and 40 healthy volunteers (mean age, 54 years) with CEUS (7 MHz; MI, 0.28) during continuous intravenous infusion of 4.8 mL microbubbles. Transient arterial occlusion at mid-thigh level simulated physical exercise. With time–CEUS–intensity curves obtained from regions of interest within calf muscles, we derived the maximum CEUS signal after occlusion (max) and its time (t max ), slope to maximum (m), vascular response after occlusion (AUC post ), and analysed accuracy, receiver operating characteristic (ROC) curves, and correlations with ankle-brachial index (ABI) and walking distance. Results: All parameters differed in PAD and volunteers (p max was delayed (31.2 ± 13.6 vs. 16.7 ± 8.5 s, p post as optimal parameter combination for diagnosing PAD and therefore impaired arterial perfusion reserve. Conclusions: Dynamic CEUS with transient arterial occlusion quantifies muscular micro-perfusion and arterial perfusion reserve. The technique is accurate to diagnose PAD.

  11. Dynamic loads during failure risk assessment of bridge crane structures

    Science.gov (United States)

    Gorynin, A. D.; Antsev, V. Yu; Shaforost, A. N.

    2018-03-01

    The paper presents the method of failure risk assessment associated with a bridge crane metal structure at the design stage. It also justifies the necessity of taking into account dynamic loads with regard to the operational cycle of a bridge crane during failure risk assessment of its metal structure.

  12. Dynamic modelling of heavy metals - time scales and target loads

    NARCIS (Netherlands)

    Posch, M.; Vries, de W.

    2009-01-01

    Over the past decade steady-state methods have been developed to assess critical loads of metals avoiding long-term risks in view of food quality and eco-toxicological effects on organisms in soils and surface waters. However, dynamic models are needed to estimate the times involved in attaining a

  13. Damage propagation in a masonry arch subjected to slow cyclic and dynamic loadings

    Directory of Open Access Journals (Sweden)

    J. Toti

    2014-07-01

    Full Text Available In the present work, the damage propagation of a masonry arch induced by slow cyclic and dynamic loadings is studied. A two-dimensional model of the arch is proposed. A nonlocal damage-plastic constitutive law is adopted to reproduce the hysteretic characteristics of the masonry material, subjected to cyclic static loadings or to harmonic dynamic excitations. In particular, the adopted cohesive model is able to take into account different softening laws in tension and in compression, plastic strains, stiffness recovery and loss due to crack closure and reopening. The latter effect is an unavoidable feature for realistically reproducing hysteretic cycles. In the studied case, an inverse procedure is used to calibrate the model parameters. Then, nonlinear static and dynamic responses of the masonry arch are described together with damage propagation paths.

  14. Application of transient analysis methodology to heat exchanger performance monitoring

    International Nuclear Information System (INIS)

    Rampall, I.; Soler, A.I.; Singh, K.P.; Scott, B.H.

    1994-01-01

    A transient testing technique is developed to evaluate the thermal performance of industrial scale heat exchangers. A Galerkin-based numerical method with a choice of spectral basis elements to account for spatial temperature variations in heat exchangers is developed to solve the transient heat exchanger model equations. Testing a heat exchanger in the transient state may be the only viable alternative where conventional steady state testing procedures are impossible or infeasible. For example, this methodology is particularly suited to the determination of fouling levels in component cooling water system heat exchangers in nuclear power plants. The heat load on these so-called component coolers under steady state conditions is too small to permit meaningful testing. An adequate heat load develops immediately after a reactor shutdown when the exchanger inlet temperatures are highly time-dependent. The application of the analysis methodology is illustrated herein with reference to an in-situ transient testing carried out at a nuclear power plant. The method, however, is applicable to any transient testing application

  15. Transient beam dynamics in the Lawrence Berkeley Laboratory 2 MV injector

    International Nuclear Information System (INIS)

    Henestroza, E.

    1996-01-01

    A driver-scale injector for the heavy ion fusion accelerator project has been built at LBL. This machine has exceeded the design goals of high voltage (above 2 MV), high current (more than 0.8 A of K + ) and low normalized emittance (less than 1 π mm mrad). The injector consists of a 750 keV gun pre-injector followed by an electrostatic quadrupole accelerator which provides strong (alternating gradient) focusing for the space-charge-dominated beam, and simultaneously accelerates the ions to 2 MeV. A matching section is being built to match the beam to the electrostatic accelerator ELISE. The gun pre-injector, designed to hold up to 1 MV with minimal breakdown risks, consists of a hot alumino-silicate source with a large curved emitting surface surrounded by a thick ''extraction electrode''. During beam turn-on the voltage at the source is biased from a negative potential, enough to reverse the electric field on the emitting surface and to avoid emission, to a positive potential to start extracting the beam; it stays constant for about 1 μs, and is reversed to turn off the emission. Since the Marx voltage applied on the accelerating quadrupoles and the main pre-injector gap is a long, constant pulse (several microseconds), the transient behavior is dominated by the extraction pulser voltage time profile. The transient longitudinal dynamics of the beam in the injector was simulated by running the particle-in-cell codes GYMNOS and WARP3D in a time-dependent mode. The generalization and its implementation is WARP3D of a method proposed by Lampel and Tiefenback to eliminate transient oscillations in a one-dimensional planar diode will be presented. (orig.)

  16. Resting state brain dynamics and its transients: a combined TMS-EEG study.

    Science.gov (United States)

    Bonnard, Mireille; Chen, Sophie; Gaychet, Jérôme; Carrere, Marcel; Woodman, Marmaduke; Giusiano, Bernard; Jirsa, Viktor

    2016-08-04

    The brain at rest exhibits a spatio-temporally rich dynamics which adheres to systematic behaviours that persist in task paradigms but appear altered in disease. Despite this hypothesis, many rest state paradigms do not act directly upon the rest state and therefore cannot confirm hypotheses about its mechanisms. To address this challenge, we combined transcranial magnetic stimulation (TMS) and electroencephalography (EEG) to study brain's relaxation toward rest following a transient perturbation. Specifically, TMS targeted either the medial prefrontal cortex (MPFC), i.e. part of the Default Mode Network (DMN) or the superior parietal lobule (SPL), involved in the Dorsal Attention Network. TMS was triggered by a given brain state, namely an increase in occipital alpha rhythm power. Following the initial TMS-Evoked Potential, TMS at MPFC enhances the induced occipital alpha rhythm, called Event Related Synchronisation, with a longer transient lifetime than TMS at SPL, and a higher amplitude. Our findings show a strong coupling between MPFC and the occipital alpha power. Although the rest state is organized around a core of resting state networks, the DMN functionally takes a special role among these resting state networks.

  17. Two Stage Secure Dynamic Load Balancing Architecture for SIP Server Clusters

    Directory of Open Access Journals (Sweden)

    G. Vennila

    2014-08-01

    Full Text Available Session Initiation Protocol (SIP is a signaling protocol emerged with an aim to enhance the IP network capabilities in terms of complex service provision. SIP server scalability with load balancing has a greater concern due to the dramatic increase in SIP service demand. Load balancing of session method (request/response and security measures optimizes the SIP server to regulate of network traffic in Voice over Internet Protocol (VoIP. Establishing a honeywall prior to the load balancer significantly reduces SIP traffic and drops inbound malicious load. In this paper, we propose Active Least Call in SIP Server (ALC_Server algorithm fulfills objectives like congestion avoidance, improved response times, throughput, resource utilization, reducing server faults, scalability and protection of SIP call from DoS attacks. From the test bed, the proposed two-tier architecture demonstrates that the ALC_Server method dynamically controls the overload and provides robust security, uniform load distribution for SIP servers.

  18. Impact of operational frequency overvoltage transients on nuclear power plant supply systems

    International Nuclear Information System (INIS)

    Aziz, Michael; Klipfel, Volkher; Behrens, Joerg; Trumm, Karl-Heinz; Bresler, Markus

    2008-01-01

    During the Forsmark-1 event from 25 th July 2006 a regular transient after load shedding caused serious impact to the power supply system due to an improper setting of the UPS protection devices. The applicability of the main security issue to German NPPs could be excluded. Nevertheless the event motivated the launch of a detailed analysis program on overvoltage transients. One main issue within this program was the study of overvoltage transients in the operational frequency range. The program was organized as a common project of the German operators with input from the authorities and the consultants, managed within the VGB (''Vereinigung der Grosskraftwerksbetreiber''). More general information to the ''VGB program'' can be found in [1, 2]. A generic model of the power supply and its protection system, the generator and the turbine turned out to be an efficient analysis approach. In a first step, the possible sources (initiating events) for overvoltage transients are identified. The scenarios resulting from the considered initiating events are evaluated with respect to their potential for causing damage in the station power supply system. In a second step those scenarios are excluded from further consideration, which can be categorized as fully covered by the design basis even under assumption with most conservative boundary conditions. In a third step the remaining scenarios for the covering transient are identified. The boundary conditions and failure postulates are assumed conservatively, but with respect to reasonable probabilistic limits. Finally the dynamics of the covering transient is simulated. (orig.)

  19. Transient two-phase flow

    International Nuclear Information System (INIS)

    Hsu, Y.Y.

    1974-01-01

    The following papers related to two-phase flow are summarized: current assumptions made in two-phase flow modeling; two-phase unsteady blowdown from pipes, flow pattern in Laval nozzle and two-phase flow dynamics; dependence of radial heat and momentum diffusion; transient behavior of the liquid film around the expanding gas slug in a vertical tube; flooding phenomena in BWR fuel bundles; and transient effects in bubble two-phase flow. (U.S.)

  20. A computational procedure for coupled electromagnetic-structural dynamic problems and its application to a fusion reactor blanket

    International Nuclear Information System (INIS)

    Jordan, T.

    1993-09-01

    A method is presented in order to couple quasistationary electromagnetics and the dynamics of structure and fluid. This method allows to compute forces, strains and stresses in structures subjected to transient magnetic fields. An important application was to determine the dynamic loading of the self-cooled liquid metal blanket during a plasma distruption. (orig./HP) [de

  1. A simplified model of dynamic interior cooling load evaluation for office buildings

    International Nuclear Information System (INIS)

    Ding, Yan; Zhang, Qiang; Wang, Zhaoxia; Liu, Min; He, Qing

    2016-01-01

    Highlights: • The core interior disturbance was determined by principle component analysis. • Influences of occupants on cooling load should be described using time series. • A simplified model was built to evaluate dynamic interior building cooling load. - Abstract: Predicted cooling load is a valuable tool for assessing the operation of air-conditioning systems. Compared with exterior cooling load, interior cooling load is more unpredictable. According to principle components analysis, occupancy was proved to be a typical factor influencing interior cooling loads in buildings. By exploring the regularity of interior disturbances in an office building, a simplified evaluation model for interior cooling load was established in this paper. The stochastic occupancy rate was represented by a Markov transition model. Equipment power, lighting power and fresh air were all related to occupancy rate based on time sequence. The superposition of different types of interior cooling loads was also considered in the evaluation model. The error between the evaluation results and measurement results was found to be lower than 10%. In reference to the cooling loads calculated by the traditional design method and area-based method in case study office rooms, the evaluated cooling loads were suitable for operation regulation.

  2. Transient Dynamic Response of Delaminated Composite Rotating Shallow Shells Subjected to Impact

    Directory of Open Access Journals (Sweden)

    Amit Karmakar

    2006-01-01

    Full Text Available In this paper a transient dynamic finite element analysis is presented to study the response of delaminated composite pretwisted rotating shallow shells subjected to low velocity normal impact. Lagrange's equation of motion is used to derive the dynamic equilibrium equation and moderate rotational speeds are considered wherein the Coriolis effect is negligible. An eight noded isoparametric plate bending element is employed in the finite element formulation incorporating rotary inertia and effects of transverse shear deformation based on Mindlin's theory. To satisfy the compatibility of deformation and equilibrium of resultant forces and moments at the delamination crack front a multipoint constraint algorithm is incorporated which leads to unsymmetric stiffness matrices. The modified Hertzian contact law which accounts for permanent indentation is utilized to compute the contact force, and the time dependent equations are solved by Newmark's time integration algorithm. Parametric studies are performed in respect of location of delamination, angle of twist and rotational speed for centrally impacted graphite-epoxy composite cylindrical shells.

  3. Dynamic characterization and modeling of magneto-rheological elastomers under compressive loadings

    International Nuclear Information System (INIS)

    Koo, Jeong-Hoi; Khan, Fazeel; Jang, Dong-Doo; Jung, Hyung-Jo

    2010-01-01

    The primary goal of the research reported in this paper has been to characterize and model the compression properties of magneto-rheological elastomers (MREs). MRE samples were fabricated by curing a two-component elastomer resin with 30% content of 10 µm sized iron particles by volume. In order to vary the magnetic field during compressive testing, a test fixture was designed and fabricated in which two permanent magnets could be variably positioned on either side of the specimen. Changing the distance between the magnets of the fixture allowed the strength of the magnetic field passing uniformly through the sample to be varied. Using this test setup and a dynamic test frame, a series of compression tests of MRE samples were performed, by varying the magnetic field and the frequency of loading. The results show that the MR effect (per cent increase in the material 'stiffness') increases as the magnetic field increases and the loading frequency increases within the range of the magnetic field and input frequency considered in this study. Furthermore, a phenomenological model was developed to capture the dynamic behaviors of the MREs under compression loadings. (technical note)

  4. Transient computational homogenization for heterogeneous materials under dynamic excitation

    NARCIS (Netherlands)

    Pham, N.K.H.; Kouznetsova, V.; Geers, M.G.D.

    2013-01-01

    This paper presents a novel transient computational homogenization procedure that is suitable for the modelling of the evolution in space and in time of materials with non-steady state microstructure, such as metamaterials. This transient scheme is an extension of the classical (first-order)

  5. Calculation of design load for the MOD-5A 7.3 mW wind turbine system

    Science.gov (United States)

    Mirandy, L.; Strain, J. C.

    1995-01-01

    Design loads are presented for the General Electric MOD-SA wind turbine. The MOD-SA system consists of a 400 ft. diameter, upwind, two-bladed, teetered rotor connected to a 7.3 mW variable-speed generator. Fatigue loads are specified in the form of histograms for the 30 year life of the machine, while limit (or maximum) loads have been derived from transient dynamic analysis at critical operating conditions. Loads prediction was accomplished using state of the art aeroelastic analyses developed at General Electric. Features of the primary predictive tool - the Transient Rotor Analysis Code (TRAC) are described in the paper. Key to the load predictions are the following wind models: (1) yearly mean wind distribution; (2) mean wind variations during operation; (3) number of start/shutdown cycles; (4) spatially large gusts; and (5) spatially small gusts (local turbulence). The methods used to develop statistical distributions from load calculations represent an extension of procedures used in past wind programs and are believed to be a significant contribution to Wind Turbine Generator analysis. Test/theory correlations are presented to demonstrate code load predictive capability and to support the wind models used in the analysis. In addition MOD-5A loads are compared with those of existing machines. The MOD-5A design was performed by the General Electric Company, Advanced Energy Program Department, under Contract DEN3-153 with NASA Lewis Research Center and sponsored by the Department of Energy.

  6. Discontinuity effects in dynamically loaded tilting pad journal bearings

    DEFF Research Database (Denmark)

    Thomsen, Kim; Klit, Peder; Vølund, Anders

    2011-01-01

    This paper describes two discontinuity effects that can occur when modelling radial tilting pad bearings subjected to high dynamic loads. The first effect to be treated is a pressure build-up discontinuity effect. The second effect is a contact-related discontinuity that disappears when a contact...... force is included in the theoretical model. Methods for avoiding the pressure build-up discontinuity effect are proposed....

  7. Time-Domain Three Dimensional BE-FE Method for Transient Response of Floating Structures Under Unsteady Loads

    Directory of Open Access Journals (Sweden)

    R. E. S. Ismail

    Full Text Available Abstract This paper presents a direct time-domain three dimensional (3D numerical procedure to simulate the transient response of very large floating structures (VLFS subjected to unsteady external loads as well as moving mass. The proposed procedure employs the Boundary Element and Finite Element methods (FEM-BEM. The floating structure and the surrounding fluid are discretized by 4-node isoparametric finite elements (FE and by 4-node constant boundary elements (BE, respectively. Structural analysis is based on Mindlin's plate theory. The equation of motion is constructed taking into account the effect of inertia loading due to the moving mass. In order to obtain the hydrodynamic forces (added mass and radiation damping, the coupled natural frequencies are first obtained by an iterative method, since hydrodynamic forces become frequency-dependent. Then the Newark integration method is employed to solve the equation of motion for structural system. In order to prove the validity of the present method, a FORTRAN program is developed and numerical examples are carried out to compare its results with those of published experimental results of a scale model of VLFS under a weight drop and airplane landing and takeoff in still water condition. The comparisons show very good agreement.

  8. Infrared Thermographic Diagnosis Mechanism for Fault Detection of Ball Bearing under Dynamic Loading Conditions

    International Nuclear Information System (INIS)

    Seo, Jin Ju; Yoon, Hanvit; Kim, Dong Yeon; Hong, Dong Pyo; Kim, Won Tae

    2011-01-01

    Fault detection for dynamic loading conditions of rotational machineries was considered from the contactless, non-destructive infrared thermographic method, rather than the traditional diagnosis method. In this paper, by applying a rotating deep-grooved ball bearing, passive thermographic experiment was performed as an alternative way proceeding the traditional fault monitoring. In addition, the thermographic experiments were compared with the vibration spectrum analysis to evaluate the efficiency of the proposed method. Based on the results, it was concluded the temperature characteristics of the ball bearing under dynamic loading conditions were analyzed thoroughly

  9. In vitro evaluation of stiffness and load sharing in a two-level corpectomy: comparison of static and dynamic cervical plates.

    Science.gov (United States)

    Fogel, Guy R; Li, Zhenyu; Liu, Weiqiang; Liao, Zhenhua; Wu, Jia; Zhou, Wenyu

    2010-05-01

    Anterior cervical plating has been accepted in corpectomy and fusion of the cervical spine. Constrained plates were criticized for stress shielding that may lead to subsidence and pseudarthrosis. A dynamic plate allows load sharing as the graft subsides. Ideally, the dynamic plate design should maintain adequate stiffness of the construct while providing a reasonable load sharing with the strut graft. The purpose of the study was to compare dynamic and static plate kinematics with graft subsidence. The study designed was an in vitro biomechanical study in a porcine cervical spine model. Twelve spines were initially tested in intact condition with 20-N axial load in 15 degrees of flexion and extension range of motion (ROM). Then, a two-level corpectomy was created in all specimens with spines randomized to receive either a static or dynamic plate. The spines were retested under identical conditions with optimal length and undersized graft. Range of motion and graft loading were analyzed with a one-way analysis of variance (p<.05). Both plates significantly limited ROM compared with the intact spine in both graft length conditions. In extension graft, load was significantly higher (p=.001) in the static plate with optimal length, and in flexion, there was a significant loss of graft load (p=.0004). In flexion, the dynamic plate with undersized graft demonstrated significantly more load sustained (p=.0004). Both plates reasonably limited the ROM of the corpectomy. The static plate had significantly higher graft loads in extension and significant loss of graft load in flexion, whereas the dynamic plate maintained a reasonable graft load in ROM even when graft contact was imperfect. Copyright 2010 Elsevier Inc. All rights reserved.

  10. COTRANSA simulation of Chinshan unit one generator load rejection test

    International Nuclear Information System (INIS)

    Wu, C.H.

    1984-01-01

    A simulation of the plant behavior during a BWR generator load rejection transient using Exxon Nuclear Company's COTRANSA code is presented in this paper. The results are compared to measurements obtained by Taiwan Power Company during a generator load rejection transient, initiated at full power condition, which was one of the Chinshan Unit 1 initial cycle startup tests. Good agreement between the COTRANSA predicted and the measured values, indicates that the COTRANSA code can simulate this transient satisfactorily

  11. Recommendations for analysis of stress corrosion in pipe systems exposed to thermohydraulic transients

    International Nuclear Information System (INIS)

    Bjoerndahl, Olof; Letzter, Adam; Marcinkiewicz, Jerzy; Segle, Peter

    2007-03-01

    Transient thermohydraulic events often control the design of piping systems in nuclear power plants. Water hammers due to valve closure, pressure transients caused by steam collapse and pipe break all result in structural loads that are characterised by a high frequency content. What also characterises these pressures/forces is the specific spatial and time dependence that is acting on the piping system and found in the wave propagation in the contained fluid. The aim with this project has been to develop recommendations for analysis of the stress response in piping systems subjected to thermohydraulic transients. Basis for this work is that the so called two-step-method is applied and that the structural response is calculated with modal superposition. Derived analysis criteria are based on the assumption that the associated volume strain energy in the wave propagation for the contained fluid may be well defined by a parameter, here called ε PN . The stress response in the piping system is assumed to be completely determined with certain accuracy for that part of the volume strain energy in the wave propagation associated with this parameter. A comprehensive work has been done to determine the accuracy in loadings calculated with RELAP5. Properties such as period elongation and associated spurious oscillations in the pressure wave transient have been investigated. Furthermore, has the characteristics of the artificial numerical damping in RELAP5 been identified. Based on desired accuracy of the thermohydraulic analysis together with knowledge about the duration of the thermohydraulic perturbation, the lowest upper frequency limit f Pipe , in the modal base that is required for the structure model is calculated. With perturbation is meant such as a valve closure. According to suggested criteria and with the upper frequency limit set, the essential parameters i) largest size of the elements in the structure model and ii) the largest applicable time step in the

  12. Erosion dynamics of tungsten fuzz during ELM-like heat loading

    Science.gov (United States)

    Sinclair, G.; Tripathi, J. K.; Hassanein, A.

    2018-04-01

    Transient heat loading and high-flux particle loading on plasma facing components in fusion reactors can lead to surface melting and possible erosion. Helium-induced fuzz formation is expected to exacerbate thermal excursions, due to a significant drop in thermal conductivity. The effect of heating in edge-localized modes (ELMs) on the degradation and erosion of a tungsten (W) fuzz surface was examined experimentally in the Ultra High Flux Irradiation-II facility at the Center for Materials Under Extreme Environment. W foils were first exposed to low-energy He+ ion irradiation at a fluence of 2.6 × 1024 ions m-2 and a steady-state temperature of 1223 K. Then, samples were exposed to 1000 pulses of ELM-like heat loading, at power densities between 0.38 and 1.51 GW m-2 and at a steady-state temperature of 1223 K. Comprehensive erosion analysis measured clear material loss of the fuzz nanostructure above 0.76 GW m-2 due to melting and splashing of the exposed surface. Imaging of the surface via scanning electron microscopy revealed that sufficient heating at 0.76 GW m-2 and above caused fibers to form tendrils to conglomerate and form droplets. Repetitive thermal loading on molten surfaces then led to eventual splashing. In situ erosion measurements taken using a witness plate and a quartz crystal microbalance showed an exponential increase in mass loss with energy density. Compositional analysis of the witness plates revealed an increase in the W 4f signal with increasing energy density above 0.76 GW m-2. The reduced thermal stability of the fuzz nanostructure puts current erosion predictions into question and strengthens the importance of mitigation techniques.

  13. Dynamic load indicators for take-off-landing sequence in blocks and attacks of elite female volleyball players.

    Science.gov (United States)

    Kabaciński, Jarosław; Dworak, Lechosław Bogdan; Murawa, Michał; Rzepnicka, Agata

    2016-01-01

    Dynamic loads during landings determined by the ground reaction forces (GRFs) may elaborate internal loads and increase the risk of overload knee injuries as a result of performing volleyball jumps many times. The study dealt with a biomechanical assessment of dynamic load indicators in female volleyball players for the motion sequence of take-off-landing in blocks and attacks. Twelve professional female volleyball players participated in the study. Blocks and attacks were filmed by two cameras. GRFs vs. time graphs were recorded with the use of a force platform. Values of dynamic load indicators in terms of the relations of peak of vertical component of GRF, build-up index of this force (BIF), and power output (P) during landing to the vGRF, BIF and P during take-off (L/T) were calculated. The statistically significant ( p volleyball players.

  14. Measurement Research of Motorized Spindle Dynamic Stiffness under High Speed Rotating

    Directory of Open Access Journals (Sweden)

    Xiaopeng Wang

    2015-01-01

    Full Text Available High speed motorized spindle has become a key functional unit of high speed machine tools and effectively promotes the development of machine tool technology. The development of higher speed and more power puts forward the stricter requirement for the performance of motorized spindle, especially the dynamic performance which affects the machining accuracy, reliability, and production efficiency. To overcome the problems of ineffective loading and dynamic performance measurement of motorized spindle, a noncontact electromagnetic loading device is developed. The cutting load can be simulated by using electromagnetic force. A new method of measuring force by force sensors is presented, and the steady and transient loading force could be measured exactly. After the high speed machine spindle is tested, the frequency response curves of the spindle relative to machine table are collected at 0~12000 rpm; then the relationships between stiffness and speeds as well as between damping ratio and speeds are obtained. The result shows that not only the static and dynamic stiffness but also the damping ratio declined with the increase of speed.

  15. Influence of foundation mass and surface roughness on dynamic response of beam on dynamic foundation subjected to the moving load

    Science.gov (United States)

    Tran Quoc, Tinh; Khong Trong, Toan; Luong Van, Hai

    2018-04-01

    In this paper, Improved Moving Element Method (IMEM) is used to analyze the dynamic response of Euler-Bernoulli beam structures on the dynamic foundation model subjected to the moving load. The effects of characteristic foundation model parameters such as Winkler stiffness, shear layer based on the Pasternak model, viscoelastic dashpot and characteristic parameter of mass on foundation. Beams are modeled by moving elements while the load is fixed. Based on the principle of the publicly virtual balancing and the theory of moving element method, the motion differential equation of the system is established and solved by means of the numerical integration based on the Newmark algorithm. The influence of mass on foundation and the roughness of the beam surface on the dynamic response of beam are examined in details.

  16. The dynamic response and perturbation of magnetic field vector of orthotropic cylinders under various shock loads

    International Nuclear Information System (INIS)

    Dai, H.L.; Wang, X.

    2006-01-01

    In this paper, an analytical method is introduced to solve the problem for the dynamic stress-focusing and centred-effect of perturbation of the magnetic field vector in orthotropic cylinders under thermal and mechanical shock loads. Analytical expressions for the dynamic stresses and the perturbation of the magnetic field vector are obtained by means of finite Hankel transforms and Laplace transforms. The response histories of dynamic stresses and the perturbation of the field vector are also obtained. In practical examples, the dynamic focusing effect on both magnetoelastic stress and perturbation of the axial magnetic field vector in an orthotropic cylinder subjected to various shock loads is presented and discussed

  17. Flight Loads Prediction of High Aspect Ratio Wing Aircraft Using Multibody Dynamics

    Directory of Open Access Journals (Sweden)

    Michele Castellani

    2016-01-01

    Full Text Available A framework based on multibody dynamics has been developed for the static and dynamic aeroelastic analyses of flexible high aspect ratio wing aircraft subject to structural geometric nonlinearities. Multibody dynamics allows kinematic nonlinearities and nonlinear relationships in the forces definition and is an efficient and promising methodology to model high aspect ratio wings, which are known to be prone to structural nonlinear effects because of the high deflections in flight. The multibody dynamics framework developed employs quasi-steady aerodynamics strip theory and discretizes the wing as a series of rigid bodies interconnected by beam elements, representative of the stiffness distribution, which can undergo arbitrarily large displacements and rotations. The method is applied to a flexible high aspect ratio wing commercial aircraft and both trim and gust response analyses are performed in order to calculate flight loads. These results are then compared to those obtained with the standard linear aeroelastic approach provided by the Finite Element Solver Nastran. Nonlinear effects come into play mainly because of the need of taking into account the large deflections of the wing for flight loads computation and of considering the aerodynamic forces as follower forces.

  18. Study on the Flare Load Estimation of the Deethanizer using Dynamic Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Park, Kyungtae; Won, Wangyun [GS EC, Seoul (Korea, Republic of); Shin, Dongil [Myongji University, Yongin (Korea, Republic of)

    2014-10-15

    A flare system is a very important system that crucially affects on the process safety in chemical plants. If a flare system is designed too small, it cannot prevent catastrophic accidents of a chemical plant. On the other hand, if a flare system is designed too large, it will waste resources. Therefore, reasonable relief load estimation has been a crucial issue in the industry. American Petroleum Institute (API) suggests basic guidelines for relief load estimation, and a lot of engineering companies have developed their own relief load estimation methods that use an unbalanced heat and material method. However, these methods have to involve lots of conservative assumptions that lead to an overestimation of relief loads. In this study, the new design procedure for a flare system based on dynamic simulation was proposed in order to avoid the overestimation of relief loads. The relief load of a deethanizer process was tested to verify the performance of the proposed design procedure.

  19. An Energy Saving Green Plug Device for Nonlinear Loads

    Science.gov (United States)

    Bloul, Albe; Sharaf, Adel; El-Hawary, Mohamed

    2018-03-01

    The paper presents a low cost a FACTS Based flexible fuzzy logic based modulated/switched tuned arm filter and Green Plug compensation (SFC-GP) scheme for single-phase nonlinear loads ensuring both voltage stabilization and efficient energy utilization. The new Green Plug-Switched filter compensator SFC modulated LC-Filter PWM Switched Capacitive Compensation Devices is controlled using a fuzzy logic regulator to enhance power quality, improve power factor at the source and reduce switching transients and inrush current conditions as well harmonic contents in source current. The FACTS based SFC-GP Device is a member of family of Green Plug/Filters/Compensation Schemes used for efficient energy utilization, power quality enhancement and voltage/inrush current/soft starting control using a dynamic error driven fuzzy logic controller (FLC). The device with fuzzy logic controller is validated using the Matlab / Simulink Software Environment for enhanced power quality (PQ), improved power factor and reduced inrush currents. This is achieved using modulated PWM Switching of the Filter-Capacitive compensation scheme to cope with dynamic type nonlinear and inrush cyclical loads..

  20. Feasibility of Applying Active Lubrication to Dynamically Loaded Fluid Film Bearings

    DEFF Research Database (Denmark)

    Estupinan, Edgar Alberto; Santos, Ilmar

    2009-01-01

    The feasibility of modifying the dynamics of the thin fluid films of dynamically loaded journal bearings, using different strategies of active lubrication is studied in this work. A significant reduction in the vibration levels, wear and power friction losses, is expected. Particularly, the focus...... of this study is on the analysis of main crankshaft bearings, where the conventional hydrodynamic lubrication is modified by injecting oil at actively controllable pressures, through orifices circumferentially located along the bearing surface....

  1. Dynamic analysis of maritime gasbag-type floating bridge subjected to moving loads

    Directory of Open Access Journals (Sweden)

    Huan-huan Wang

    2016-03-01

    Full Text Available This paper studied the dynamic response of a new gasbag-type floating bridge under the effect of a moving load. The arbitrary Lagrangian-Eulerian (ALE method was used to simulate the movement of seawater and air, and the penalty-based method was used to study the coupling between gasbags and fluid. A three-dimensional finite element model of the floating bridge was established, and the numerical model was verified by comparing with the experimental results. In order to prevent resonance, the natural frequencies and flexural mode shapes were analyzed. Based on the initial state analysis, the dynamic responses of the floating bridge subjected to different moving loads were investigated. Vertical displacements and radial deformations of gasbags under different loads were compared, and principal stress distributions of gasbags were researched while driving. The hinge forces between adjacent modules were calculated to ensure the connection strength. Besides, the floating bridge under wave impacting was analyzed. Those results can provide references for the analysis and design of this new floating bridge.

  2. Analysis of the Dynamic Response in Blast-Loaded CFRP-Strengthened Metallic Beams

    Directory of Open Access Journals (Sweden)

    Zhenyu Wang

    2013-01-01

    Full Text Available Carbon fiber-reinforced polymer composites (CFRPs are good candidates in enhancing the blast resistant performance of vulnerable public buildings and in reinforcing old buildings. The use of CFRP in retrofitting and strengthening applications is traditionally associated with concrete structures. Nevertheless, more recently, there has been a remarkable aspiration in strengthening metallic structures and components using CFRP. This paper presents a relatively simple analytical solution for the deformation and ultimate strength calculation of hybrid metal-CFRP beams when subjected to pulse loading, with a particular focus on blast loading. The analytical model is based on a full interaction between the metal and the FRP and is capable of producing reasonable results in a dynamic loading scenario. A nonlinear finite element (FE model is also developed to reveal the full dynamic behavior of the CFRP-epoxy-steel hybrid beam, considering the detailed effects, that is, large strains, high strain rates in metal, and different failure modes of the hybrid beam. Experimental results confirm the analytical and the FE results and show a strong correlation.

  3. Transient identification system with noising data and 'don't know' response

    International Nuclear Information System (INIS)

    Mol, Antonio C. de A.; Martinez, Aquilino S.; Schirru, Roberto

    2002-01-01

    In the last years, many different approaches based on neural network (NN) has been proposed for transient identification in nuclear power plants (NPP). Some of them focus the dynamic identification using recurrent neural networks however, they are not able to deal with unrecognized transients. Other kind of solution uses competitive learning in order to allow the 'don't know' response. In this case dynamic, dynamic features are not well represented. This work presents a new approach for neural network based transient identification which allows either dynamic identification and 'don't know'response. Such approach uses two multilayer neural networks trained with backpropagation algorithm. The first one is responsible for the dynamic identification. This NN uses, a short set (in a movable time window) of recent measurements of each variable avoiding the necessity of using starting events. The other one is used to validate the instantaneous identification (from the first net) through the validation of each variable. This net is responsible for allowing the system to provide 'don't know' response. In order to validate the method a NPP transient identification problem comprising 15 postulated accidents, simulated for a pressurized water reactor, was proposed in the validation process it has been considered noising data in other to evaluate the method robustness. Obtained results reveal the ability of the method in dealing with both dynamic identification of transients and correct 'don't know' response. In order to validate the method, a NPP transient identification problem comprising 15 postulated accidents simulated for a pressurized water reactor, was proposed in the validation process it has been considered noising data in order to evaluate the method robustness. Obtained results reveal the ability of the method in dealing with both dynamic identification of transients and correct 'don't know' response. (author)

  4. Dynamic Load Balancing Based on Constrained K-D Tree Decomposition for Parallel Particle Tracing

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jiang; Guo, Hanqi; Yuan, Xiaoru; Hong, Fan; Peterka, Tom

    2018-01-01

    Particle tracing is a fundamental technique in flow field data visualization. In this work, we present a novel dynamic load balancing method for parallel particle tracing. Specifically, we employ a constrained k-d tree decomposition approach to dynamically redistribute tasks among processes. Each process is initially assigned a regularly partitioned block along with duplicated ghost layer under the memory limit. During particle tracing, the k-d tree decomposition is dynamically performed by constraining the cutting planes in the overlap range of duplicated data. This ensures that each process is reassigned particles as even as possible, and on the other hand the new assigned particles for a process always locate in its block. Result shows good load balance and high efficiency of our method.

  5. Nonlinear dynamic response of electro-thermo-mechanically loaded piezoelectric cylindrical shell reinforced with BNNTs

    International Nuclear Information System (INIS)

    Yang, J H; Yang, J; Kitipornchai, S

    2012-01-01

    This paper presents an investigation on the nonlinear dynamic response of piezoelectric cylindrical shells reinforced with boron nitride nanotubes (BNNTs) under a combined axisymmetric electro-thermo-mechanical loading. By employing the classical Donnell shell theory, the von Kármán–Donnell kinematic relationship, and a piezo-elastic constitutive law including thermal effects, the nonlinear governing equations of motion of the shell are derived through the Reissner variational principle. The finite difference method and a time-integration scheme are used to obtain the nonlinear dynamic response of the BNNT-reinforced piezoelectric shell. A parametric study is conducted, showing the effects of geometrically nonlinear deformation, applied voltage, temperature change, mechanical load, BNNT volume fraction and boundary conditions on the nonlinear dynamic response. (paper)

  6. The OECD/NEA/NSC PBMR 400 MW coupled neutronics thermal hydraulics transient benchmark: transient results - 290

    International Nuclear Information System (INIS)

    Strydom, G.; Reitsma, F.; Ngeleka, P.T.; Ivanov, K.N.

    2010-01-01

    The PBMR is a High-Temperature Gas-cooled Reactor (HTGR) concept developed to be built in South Africa. The analysis tools used for core neutronic design and core safety analysis need to be verified and validated, and code-to-code comparisons are an essential part of the V and V plans. As part of this plan the PBMR 400 MWth design and a representative set of transient exercises are defined as an OECD benchmark. The scope of the benchmark is to establish a series of well defined multi-dimensional computational benchmark problems with a common given set of cross sections, to compare methods and tools in coupled neutronics and thermal hydraulics analysis with a specific focus on transient events. This paper describes the current status of the benchmark project and shows the results for the six transient exercises, consisting of three Loss of Cooling Accidents, two Control Rod Withdrawal transients, a power load-follow transient, and a Helium over-cooling Accident. The participants' results are compared using a statistical method and possible areas of future code improvement are identified. (authors)

  7. Transient dynamic and modeling parameter sensitivity analysis of 1D solid oxide fuel cell model

    International Nuclear Information System (INIS)

    Huangfu, Yigeng; Gao, Fei; Abbas-Turki, Abdeljalil; Bouquain, David; Miraoui, Abdellatif

    2013-01-01

    Highlights: • A multiphysics, 1D, dynamic SOFC model is developed. • The presented model is validated experimentally in eight different operating conditions. • Electrochemical and thermal dynamic transient time expressions are given in explicit forms. • Parameter sensitivity is discussed for different semi-empirical parameters in the model. - Abstract: In this paper, a multiphysics solid oxide fuel cell (SOFC) dynamic model is developed by using a one dimensional (1D) modeling approach. The dynamic effects of double layer capacitance on the electrochemical domain and the dynamic effect of thermal capacity on thermal domain are thoroughly considered. The 1D approach allows the model to predict the non-uniform distributions of current density, gas pressure and temperature in SOFC during its operation. The developed model has been experimentally validated, under different conditions of temperature and gas pressure. Based on the proposed model, the explicit time constant expressions for different dynamic phenomena in SOFC have been given and discussed in detail. A parameters sensitivity study has also been performed and discussed by using statistical Multi Parameter Sensitivity Analysis (MPSA) method, in order to investigate the impact of parameters on the modeling accuracy

  8. On the equivalent static loads approach for dynamic response structural optimization

    DEFF Research Database (Denmark)

    Stolpe, Mathias

    2014-01-01

    The equivalent static loads algorithm is an increasingly popular approach to solve dynamic response structural optimization problems. The algorithm is based on solving a sequence of related static response structural optimization problems with the same objective and constraint functions...... as the original problem. The optimization theoretical foundation of the algorithm is mainly developed in Park and Kang (J Optim Theory Appl 118(1):191–200, 2003). In that article it is shown, for a certain class of problems, that if the equivalent static loads algorithm terminates then the KKT conditions...

  9. An Analysis on a Dynamic Amplifier and Calibration Methods for a Pseudo-Differential Dynamic Comparator

    Science.gov (United States)

    Paik, Daehwa; Miyahara, Masaya; Matsuzawa, Akira

    This paper analyzes a pseudo-differential dynamic comparator with a dynamic pre-amplifier. The transient gain of a dynamic pre-amplifier is derived and applied to equations of the thermal noise and the regeneration time of a comparator. This analysis enhances understanding of the roles of transistor's parameters in pre-amplifier's gain. Based on the calculated gain, two calibration methods are also analyzed. One is calibration of a load capacitance and the other is calibration of a bypass current. The analysis helps designers' estimation for the accuracy of calibration, dead-zone of a comparator with a calibration circuit, and the influence of PVT variation. The analyzed comparator uses 90-nm CMOS technology as an example and each estimation is compared with simulation results.

  10. Improved pump turbine transient behaviour prediction using a Thoma number-dependent hillchart model

    International Nuclear Information System (INIS)

    Manderla, M; Koutnik, J; Kiniger, K

    2014-01-01

    Water hammer phenomena are important issues for high head hydro power plants. Especially, if several reversible pump-turbines are connected to the same waterways there may be strong interactions between the hydraulic machines. The prediction and coverage of all relevant load cases is challenging and difficult using classical simulation models. On the basis of a recent pump-storage project, dynamic measurements motivate an improved modeling approach making use of the Thoma number dependency of the actual turbine behaviour. The proposed approach is validated for several transient scenarios and turns out to increase correlation between measurement and simulation results significantly. By applying a fully automated simulation procedure broad operating ranges can be covered which provides a consistent insight into critical load case scenarios. This finally allows the optimization of the closing strategy and hence the overall power plant performance

  11. Improved pump turbine transient behaviour prediction using a Thoma number-dependent hillchart model

    Science.gov (United States)

    Manderla, M.; Kiniger, K.; Koutnik, J.

    2014-03-01

    Water hammer phenomena are important issues for high head hydro power plants. Especially, if several reversible pump-turbines are connected to the same waterways there may be strong interactions between the hydraulic machines. The prediction and coverage of all relevant load cases is challenging and difficult using classical simulation models. On the basis of a recent pump-storage project, dynamic measurements motivate an improved modeling approach making use of the Thoma number dependency of the actual turbine behaviour. The proposed approach is validated for several transient scenarios and turns out to increase correlation between measurement and simulation results significantly. By applying a fully automated simulation procedure broad operating ranges can be covered which provides a consistent insight into critical load case scenarios. This finally allows the optimization of the closing strategy and hence the overall power plant performance.

  12. Modeling the dynamic stiffness of cracked reinforced concrete beams under low-amplitude vibration loads

    Science.gov (United States)

    Xu, Tengfei; Castel, Arnaud

    2016-04-01

    In this paper, a model, initially developed to calculate the stiffness of cracked reinforced concrete beams under static loading, is used to assess the dynamic stiffness. The model allows calculating the average inertia of cracked beams by taking into account the effect of bending cracks (primary cracks) and steel-concrete bond damage (i.e. interfacial microcracks). Free and forced vibration experiments are used to assess the performance of the model. The respective influence of bending cracks and steel-concrete bond damage on both static and dynamic responses is analyzed. The comparison between experimental and simulated deflections confirms that the effects of both bending cracks and steel-concrete bond loss should be taken into account to assess reinforced concrete stiffness under service static loading. On the contrary, comparison of experimental and calculated dynamic responses reveals that localized steel-concrete bond damages do not influence significantly the dynamic stiffness and the fundamental frequency.

  13. Excellent plasticity of a new Ti-based metallic glass matrix composite upon dynamic loading

    Energy Technology Data Exchange (ETDEWEB)

    Wu, R.F. [Laboratory of Applied Physics and Mechanics of Advanced Materials, College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081 (China); Jiao, Z.M. [Institute of Applied Mechanics and Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Wang, Y.S.; Wang, Z. [Laboratory of Applied Physics and Mechanics of Advanced Materials, College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Wang, Z.H.; Ma, S.G. [Institute of Applied Mechanics and Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Qiao, J.W., E-mail: qiaojunwei@gmail.com [Laboratory of Applied Physics and Mechanics of Advanced Materials, College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081 (China)

    2016-11-20

    Quasi-static and dynamic compressive properties of in-situ Ti{sub 60}Zr{sub 14}V{sub 12}Cu{sub 4}Be{sub 10} bulk metallic glass matrix composites containing ductile dendrites were investigated. Upon quasi-static compressive loading, the composite exhibits a high fracture strength of ~2,600 MPa, combined with a considerable plasticity of ~40% at room temperature. However, upon dynamic loading, an excellent plasticity of ~16% can be obtained due to the abundant dislocations and severe lattice distortions within dendrites and multiplication of shear bands within the glass matrix analyzed by transmission-electron microscopy. A constitutive relationship is obtained by Johnson-Cook plasticity model, which is employed to model the dynamic flow stress behavior. In addition, under dynamic compression, the adiabatic temperature rise increases with increasing strain rates, resulting in that the softening effect within the glass matrix is obviously enhanced during deformation.

  14. Evaluation of resilient abutment components on measured strain using dynamic loading conditions.

    Science.gov (United States)

    Morton, D; Stanford, C M; Aquilino, S A

    1998-07-01

    Factors that affect transmission of strain from prostheses to bone may affect the long-term success of loaded implants. Current in vitro models are theoretically predictive (finite element modeling) or facsimile (photoelastic) in nature. A more clinically relevant in vitro model for strain evaluation should be investigated. This study attempted: (1) to validate a human cadaver bone model for vitro measurement of cortical bone strain, and (2) to evaluate the effect on cortical strain measurements of a resilient plastic component incorporated within a titanium implant in response to variable dynamic loading. Two IMZ (Interpore International) abutment alternatives were used: the titanium Abutment Complete and the polyoxymethylene Intra-mobile Element. The model system consisted of two implants placed in unfixed human cadaver ulna bone to simulate an implant bound edentulous region. Four biaxial rosette strain gauges simultaneously recorded cortical bone strain immediately mesial and distal to each implant. During experimentation a simulated prosthetic framework supported by either titanium or polyoxymethylene abutments was dynamically loaded 6 min from the terminal abutment along a cantilever extension. Cyclic nominal peak loads were applied with a materials testing machine at 20-N intervals from 20 to 200 N at a crosshead speed of 5 mm/minute. The protocol allowed frequency of load application to vary. A Newtonian linear correlation (r2 > or = 0.98) between load application and strain output was determined for each gauge position except for the terminal gauge located opposite the cantilever. Cortical strains recorded were within reported physiologic ranges involved in bone modeling and remodeling. Further, the polyoxymethylene abutment components did not result in reduction of peak microstrain at any gauge position. The Intra-mobile Element abutments, however, did increase the time required to complete 10 loading cycles when compared with the titanium Abutment

  15. Wake Influence on Dynamic Load Characteristics of Offshore Floating Wind Turbines

    DEFF Research Database (Denmark)

    Jeon, Minu; Lee, Soogab; Kim, Taeseong

    2016-01-01

    Because the flow conditions of an offshore floating wind turbine and onshore fixed wind turbine differ, it is debatable whether the aerodynamic load predictions of an offshore floating wind turbine using the conventional blade-element momentum theory, which does not consider the dynamic wake effe...

  16. Reaction-based small-molecule fluorescent probes for dynamic detection of ROS and transient redox changes in living cells and small animals.

    Science.gov (United States)

    Lü, Rui

    2017-09-01

    Dynamic detection of transient redox changes in living cells and animals has broad implications for human health and disease diagnosis, because intracellular redox homeostasis regulated by reactive oxygen species (ROS) plays important role in cell functions, normal physiological functions and some serious human diseases (e.g., cancer, Alzheimer's disease, diabetes, etc.) usually have close relationship with the intracellular redox status. Small-molecule ROS-responsive fluorescent probes can act as powerful tools for dynamic detection of ROS and redox changes in living cells and animals through fluorescence imaging techniques; and great advances have been achieved recently in the design and synthesis of small-molecule ROS-responsive fluorescent probes. This article highlights up-to-date achievements in designing and using the reaction-based small-molecule fluorescent probes (with high sensitivity and selectivity to ROS and redox cycles) in the dynamic detection of ROS and transient redox changes in living cells and animals through fluorescence imaging. Copyright © 2017. Published by Elsevier Ltd.

  17. Dynamic analysis of reactor containment subjected to aircraft impact loading

    International Nuclear Information System (INIS)

    Li Xiaotian; He Shuyan

    2004-01-01

    In this paper, dynamic character of reactor containment subjected to aircraft impact loading is analyzed with MSC.DYTRAN program. The displacement of concrete and velocity curve of airplane is obtained. The results of the different material model are compared with empirical formula. It is concluded that reasonable result can be obtained using cap model for concrete

  18. Influence of dynamic compressive loading on the in vitro degradation behavior of pure PLA and Mg/PLA composite.

    Science.gov (United States)

    Li, Xuan; Qi, Chenxi; Han, Linyuan; Chu, Chenglin; Bai, Jing; Guo, Chao; Xue, Feng; Shen, Baolong; Chu, Paul K

    2017-12-01

    The effects of dynamic compressive loading on the in vitro degradation behavior of pure poly-lactic acid (PLA) and PLA-based composite unidirectionally reinforced with micro-arc oxidized magnesium alloy wires (Mg/PLA) are investigated. Dynamic compressive loading is shown to accelerate degradation of pure PLA and Mg/PLA. As the applied stress is increased from 0.1MPa to 0.9MPa or frequency from 0.5Hz to 2.5Hz, the overall degradation rate goes up. After immersion for 21days at 0.9MPa and 2.5Hz, the bending strength retention of the composite and pure PLA is 60.1% and 50%, respectively. Dynamic loading enhances diffusion of small acidic molecules resulting in significant pH decrease in the immersion solution. The synergistic reaction between magnesium alloy wires and PLA in the composite is further clarified by electrochemical tests. The degradation behavior of the pure PLA and PLA matrix in the composite under dynamic conditions obey the first order degradation kinetics and a numerical model is postulated to elucidate the relationship of the bending strength, stress, frequency, and immersion time under dynamic conditions. We systematically study the influence of dynamic loading on the degradation behavior of pure PLA and Mg/PLA. Dynamic compressive loading is shown to accelerate degradation of pure PLA and Mg/PLA. The synergistic reaction between magnesium alloy wires and PLA in the composite is firstly clarified by electrochemical tests. The degradation behavior of the pure PLA and PLA matrix in the composite under dynamic conditions obey the first order degradation kinetics. Then, a numerical model is postulated to elucidate the relationship of the bending strength, stress, frequency, and immersion time under dynamic conditions. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  19. Investigation of switch designs for the dynamic load current multiplier scheme on the SPHYNX microsecond linear transformer driver

    International Nuclear Information System (INIS)

    Maysonnave, T.; Bayol, F.; Demol, G.; Almeida, T. d'; Lassalle, F.; Morell, A.; Grunenwald, J.; Chuvatin, A.S.; Pecastaing, L.; De Ferron, A.S.

    2014-01-01

    SPHINX is a microsecond linear transformer driver LTD, used essentially for implosion of Z-pinch loads in direct drive mode. It can deliver a 6-MA current pulse within 800 ns into a Z-pinch load. The dynamic load current multiplier concept enables the current pulse to be modified by increasing its amplitude while reducing its rise time before being delivered to the load. This compact system is made up of concentric electrodes (auto transformer), a dynamic flux extruder (cylindrical wire array), a vacuum convolute (eight post-holes), and a vacuum closing switch, which is the key component of the system. Several different schemes are investigated for designing a vacuum switch suitable for operating the dynamic load current multiplier on the SPHINX generator for various applications, including isentropic compression experiments and Z-pinch radiation effects studies. In particular, the design of a compact vacuum surface switch and a multichannel vacuum switch, located upstream of the load are studied. Electrostatic simulations supporting the switch designs are presented along with test bed experiments. Initial results from shots on the SPHINX driver are also presented. (authors)

  20. Dynamic simulation of a beta-type Stirling engine with cam-drive mechanism via the combination of the thermodynamic and dynamic models

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Chin-Hsiang; Yu, Ying-Ju [Department of Aeronautics and Astronautics, National Cheng Kung University, No. 1, Ta-Shieh Road, Tainan, Taiwan (China)

    2011-02-15

    Dynamic simulation of a beta-type Stirling engine with cam-drive mechanism used in concentrating solar power system has been performed. A dynamic model of the mechanism is developed and then incorporated with the thermodynamic model so as to predict the transient behavior of the engine in the hot-start period. In this study, the engine is started from an initial rotational speed. The torques exerted by the flywheel of the engine at any time instant can be calculated by the dynamic model as long as the gas pressures in the chambers, the mass inertia, the friction force, and the external load have been evaluated. The instantaneous rotation speed of the engine is then determined by integration of the equation of rotational motion with respect to time, which in return affects the instantaneous variations in pressure and other thermodynamic properties of the gas inside the chambers. Therefore, the transient variations in gas properties inside the engine chambers and the dynamic behavior of the engine mechanism should be handled simultaneously via the coupling of the thermodynamic and dynamic models. An extensive parametric study of the effects of different operating and geometrical parameters has been performed, and results regarding the effects of mass moment of inertia of the flywheel, initial rotational speed, initial charged pressure, heat source temperature, phase angle, gap size, displacer length, and piston stroke on the engine transient behavior are investigated. (author)

  1. Dynamic Operation and Simulation of Post-Combustion CO2 Capture

    DEFF Research Database (Denmark)

    Gaspar, Jozsef; Gladis, Arne; Jørgensen, John Bagterp

    2016-01-01

    Thermal power need to operate, on a daily basis, with frequent and fast load changes to balance the large variations of intermittent energy sources, such as wind and solar energy. To make the integration of carbon capture to power plants economically and technically feasible, the carbon capture...... process has to be able to follow these fast and large load changes without decreasing the overall performance of the carbon capture plant. Therefore, dynamic models for simulation, optimization and control system design are essential. In this work, we compare the transient behavior of the model against...

  2. Thermal-hydraulic transient characteristics of ship-propulsion reactor investigated through safety analysis

    International Nuclear Information System (INIS)

    Fujiki, Kazuo; Asaka, Hideaki; Ishida, Toshihisa

    1986-01-01

    Thermal-hydraulic behaviors in the reactor of Nuclear Ship ''Mutsu'' were investigated through safety evaluation of operational transients by using RETRAN and COBRA-IV codes. The results were compared to the transient behaviors of typical commercial PWR and the characteristics of transient thermal-hydraulic behaviors in ship-loaded reactor were figured out. ''Mutsu'' reactor has larger thermal margin than commercial PWR because it is designed to be used as ship-propulsion power source in the load-following operation mode. This margin makes transient behavior in general milder than in commercial PWR but high opening pressure set point of main-steam safety valves leads poor heat-sink condition after reactor trip. The effects of other small-sized components are also investigated. The findings in the paper will be helpful in the design of future advanced reactor for nuclear ship. (author)

  3. Acoustics and voiding dynamics during SLSF simulations of LMFBR undercooling transients

    International Nuclear Information System (INIS)

    Anderson, T.T.; Kuzay, T.M.; Marr, W.W.; Miles, K.J.; Pedersen, D.R.; Thompson, D.H.; Wilson, R.E.

    1978-01-01

    The SLSF is the largest U.S. in-reactor test vehicle for steady-state and transient experiments in an environment typical of a LMFBR core. The SLSF experiment program, sponsored by the Department of Energy, contributes to the LMFBR safety assurance program by providing data on key phenomena that occur during postulated reactor accidents. This paper describes completed SLSF experiments, in-core instrumentation used, and methods of data interpretation to determine sodium boiling and voiding dynamics. Boiling inception is shown to be identifiable from several types of in-core instruments. Location of the boiling front and void growth derived from experimental data are compared with analytical predictions. These and other data form the basis to improve understanding of accidents and to validate or guide the development of accident analysis methods

  4. Effect of random microstructure on crack propagation in cortical bone tissue under dynamic loading

    International Nuclear Information System (INIS)

    Gao, X; Li, S; Adel-Wahab, A; Silberschmidt, V

    2013-01-01

    A fracture process in a cortical bone tissue depends on various factors, such as bone loss, heterogeneous microstructure, variation of its material properties and accumulation of microcracks. Therefore, it is crucial to comprehend and describe the effect of microstructure and material properties of the components of cortical bone on crack propagation in a dynamic loading regime. At the microscale level, osteonal bone demonstrates a random distribution of osteons imbedded in an interstitial matrix and surrounded by a thin layer known as cement line. Such a distribution of osteons can lead to localization of deformation processes. The global mechanical behavior of bone and the crack-propagation process are affected by such localization under external loads. Hence, the random distribution of microstructural features plays a key role in the fracture process of cortical bone. The purpose of this study is two-fold: firstly, to develop two-dimensional microstructured numerical models of cortical bone tissue in order to examine the interaction between the propagating crack and bone microstructure using an extended finite-element method under both quasi-static and dynamic loading conditions; secondly, to investigate the effect of randomly distributed microstructural constituents on the crack propagation processes and crack paths. The obtained results of numerical simulations showed the influence of random microstructure on the global response of bone tissue at macroscale and on the crack-propagation process for quasi-static and dynamic loading conditions

  5. Dynamic Load on a Pipe Caused by Acetylene Detonations – Experiments and Theoretical Approaches

    Directory of Open Access Journals (Sweden)

    Axel Sperber

    1999-01-01

    Full Text Available The load acting on the wall of a pipe by a detonation, which is travelling through, is not yet well characterized. The main reasons are the limited amount of sufficiently accurate pressure time history data and the requirement of considering the dynamics of the system. Laser vibrometry measurements were performed to determine the dynamic response of the pipe wall on a detonation. Different modelling approaches were used to quantify, theoretically, the radial displacements of the pipe wall. There is good agreement between measured and predicted values of vibration frequencies and the propagation velocities of transverse waves. Discrepancies mainly due to wave propagation effects were found in the amplitudes of the radial velocities. They might be overcome by the use of a dynamic load factor or improved modelling methods.

  6. Dynamic nonlinear analysis of shells of revolution

    International Nuclear Information System (INIS)

    Riesemann, W.A. von; Stricklin, J.A.; Haisler, W.E.

    1975-01-01

    Over the past few years a series of finite element computer programs have been developed at Texas A and M University for the static and dynamic nonlinear analysis of shells of revolution. This paper discusses one of these, DYNAPLAS, which is a program for the transient response of ring stiffened shells of revolution subjected to either asymmetric initial velocities or to asymmetric pressure loadings. Both material and geometric nonlinearities may be considered. (Auth.)

  7. Transient identification system with noising data and 'don't know' response; Sistema de identificacao de transientes com inclusao de ruidos e indicacao de eventos desconhecidos

    Energy Technology Data Exchange (ETDEWEB)

    Mol, Antonio C. de A. [Instituto de Engenharia Nuclear (IEN), Rio de Janeiro, RJ (Brazil). Div. de Confiabilidade Humana; Martinez, Aquilino S.; Schirru, Roberto [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia. Programa de Engenharia Nuclear

    2002-07-01

    In the last years, many different approaches based on neural network (NN) has been proposed for transient identification in nuclear power plants (NPP). Some of them focus the dynamic identification using recurrent neural networks however, they are not able to deal with unrecognized transients. Other kind of solution uses competitive learning in order to allow the 'don't know' response. In this case dynamic, dynamic features are not well represented. This work presents a new approach for neural network based transient identification which allows either dynamic identification and 'don't know'response. Such approach uses two multilayer neural networks trained with backpropagation algorithm. The first one is responsible for the dynamic identification. This NN uses, a short set (in a movable time window) of recent measurements of each variable avoiding the necessity of using starting events. The other one is used to validate the instantaneous identification (from the first net) through the validation of each variable. This net is responsible for allowing the system to provide 'don't know' response. In order to validate the method a NPP transient identification problem comprising 15 postulated accidents, simulated for a pressurized water reactor, was proposed in the validation process it has been considered noising data in other to evaluate the method robustness. Obtained results reveal the ability of the method in dealing with both dynamic identification of transients and correct 'don't know' response. In order to validate the method, a NPP transient identification problem comprising 15 postulated accidents simulated for a pressurized water reactor, was proposed in the validation process it has been considered noising data in order to evaluate the method robustness. Obtained results reveal the ability of the method in dealing with both dynamic identification of transients and correct 'don't know

  8. Transient Vibrations of an Elastic Cylinder Inserted in the Elastic Medium

    Directory of Open Access Journals (Sweden)

    Sulym Heorgij

    2016-06-01

    Full Text Available Using method of Laguerre polynomials we have obtained the solution of the dynamic problem of the theory of elasticity for elastic cylinder inserted into massive body modeled as a space. The source of non-stationary processes in composite is high intensity force load of the inner surface of the cylinder. On the surface separation of materials of space and cylinder the conditions of ideal mechanical contact are satisfied. The solution is obtained as series of Laguerre polynomials, which coefficients are found from recurrent relations. The results of numerical analysis of transient stress-strain state in elastic space with cylindrical insertion might be used for the technological process of hydraulic fracturing during shale gas extraction.

  9. Using Maximal Isometric Force to Determine the Optimal Load for Measuring Dynamic Muscle Power

    Science.gov (United States)

    Spiering, Barry A.; Lee, Stuart M. C.; Mulavara, Ajitkumar P.; Bentley, Jason R.; Nash, Roxanne E.; Sinka, Joseph; Bloomberg, Jacob J.

    2009-01-01

    Maximal power output occurs when subjects perform ballistic exercises using loads of 30-50% of one-repetition maximum (1-RM). However, performing 1-RM testing prior to power measurement requires considerable time, especially when testing involves multiple exercises. Maximal isometric force (MIF), which requires substantially less time to measure than 1-RM, might be an acceptable alternative for determining the optimal load for power testing. PURPOSE: To determine the optimal load based on MIF for maximizing dynamic power output during leg press and bench press exercises. METHODS: Twenty healthy volunteers (12 men and 8 women; mean +/- SD age: 31+/-6 y; body mass: 72 +/- 15 kg) performed isometric leg press and bench press movements, during which MIF was measured using force plates. Subsequently, subjects performed ballistic leg press and bench press exercises using loads corresponding to 20%, 30%, 40%, 50%, and 60% of MIF presented in randomized order. Maximal instantaneous power was calculated during the ballistic exercise tests using force plates and position transducers. Repeated-measures ANOVA and Fisher LSD post hoc tests were used to determine the load(s) that elicited maximal power output. RESULTS: For the leg press power test, six subjects were unable to be tested at 20% and 30% MIF because these loads were less than the lightest possible load (i.e., the weight of the unloaded leg press sled assembly [31.4 kg]). For the bench press power test, five subjects were unable to be tested at 20% MIF because these loads were less than the weight of the unloaded aluminum bar (i.e., 11.4 kg). Therefore, these loads were excluded from analysis. A trend (p = 0.07) for a main effect of load existed for the leg press exercise, indicating that the 40% MIF load tended to elicit greater power output than the 60% MIF load (effect size = 0.38). A significant (p . 0.05) main effect of load existed for the bench press exercise; post hoc analysis indicated that the effect of

  10. Multiharmonic rf feedforward system for compensation of beam loading and periodic transient effects in magnetic-alloy cavities of a proton synchrotron

    Directory of Open Access Journals (Sweden)

    Fumihiko Tamura

    2013-05-01

    Full Text Available Beam loading compensation is a key for acceleration of a high intensity proton beam in the main ring (MR of the Japan Proton Accelerator Research Complex (J-PARC. Magnetic alloy loaded rf cavities with a Q value of 22 are used to achieve high accelerating voltages without a tuning bias loop. The cavity is driven by a single harmonic (h=9 rf signal while the cavity frequency response also covers the neighbor harmonics (h=8,10. Therefore the wake voltage induced by the high intensity beam consists of the three harmonics, h=8,9,10. The beam loading of neighbor harmonics is the source of periodic transient effects and a possible source of coupled bunch instabilities. In the article, we analyze the wake voltage induced by the high intensity beam. We employ the rf feedforward method to compensate the beam loading of these three harmonics (h=8,9,10. The full-digital multiharmonic feedforward system was developed for the MR. We describe the system architecture and the commissioning methodology of the feedforward patterns. The commissioning of the feedforward system has been performed by using high intensity beams with 1.0×10^{14} proteins per pulse. The impedance seen by the beam is successfully reduced and the longitudinal oscillations due to the beam loading are reduced. By the beam loading compensation, stable high power beam operation is achieved. We also report the reduction of the momentum loss during the debunching process for the slow extraction by the feedforward.

  11. Electromechanical responses of a long piezoelectric tube subjected to dynamic loading

    International Nuclear Information System (INIS)

    Huang, Jin H; Shiah, Y C; Lee, Bing Jean

    2008-01-01

    This paper deals with the fully coupled electromechanical response of a long piezoelectric tube subjected to periodic excitation loads. By adopting the variation approach for generalized loading conditions and utilizing Hamilton's principle, the governing differential equations are described in this paper. For studying the direct and converse effect of the piezoelectric tube, the equations of motion are then solved to give exact solutions corresponding to different boundary conditions prescribed for the tube functioning as sensors or actuators. For numerical illustrations of our analysis, a long tube made of polyvinylidene difluoride is investigated for its dynamic responses under different harmonic excitation loads. Contributing to the development of novel acousto-optic, actuator and sensor devices, this work may be extended to investigating the electromechanical responses of piezoelectric coatings on optical fibres

  12. Composite slab behavior and strength analysis under static and dynamic loads

    Directory of Open Access Journals (Sweden)

    Florin Radu HARIGA

    2012-07-01

    Full Text Available Steel-framed buildings are typically constructed using steel-deck-reinforced concrete floor slabs. The in-plane (or diaphragm strength and stiffness of the floor system are frequently utilized in the lateral load-resisting system design. This paper presents the results of an experimental research program in which four full size composite diaphragms were vertically loaded to the limit state, under static or dynamic loads. Two test specimens were provided with longitudinal steel-deck ribs, and the other two specimens with cross steel-deck ribs. Typical composite diaphragm limit states are described, and the controlling limit state for each of the full size tests is indicated. The interaction effects between the reinforced concrete slab and the steel girder on the composite slab strength and stiffness were mainly studied.

  13. Static and dynamic load-balancing strategies for parallel reservoir simulation

    International Nuclear Information System (INIS)

    Anguille, L.; Killough, J.E.; Li, T.M.C.; Toepfer, J.L.

    1995-01-01

    Accurate simulation of the complex phenomena that occur in flow in porous media can tax even the most powerful serial computers. Emergence of new parallel computer architectures as a future efficient tool in reservoir simulation may overcome this difficulty. Unfortunately, major problems remain to be solved before using parallel computers commercially: production serial programs must be rewritten to be efficient in parallel environments and load balancing methods must be explored to evenly distribute the workload on each processor during the simulation. This study implements both a static load-balancing algorithm and a receiver-initiated dynamic load-sharing algorithm to achieve high parallel efficiencies on both the IBM SP2 and Intel IPSC/860 parallel computers. Significant speedup improvement was recorded for both methods. Further optimization of these algorithms yielded a technique with efficiencies as high as 90% and 70% on 8 and 32 nodes, respectively. The increased performance was the result of the minimization of message-passing overhead

  14. Numerical modelling of closed-cell aluminium foam under dynamic loading

    Science.gov (United States)

    Hazell, Paul; Kader, M. A.; Islam, M. A.; Escobedo, J. P.; Saadatfar, M.

    2015-06-01

    Closed-cell aluminium foams are extensively used in aerospace and automobile industries. The understanding of their behaviour under impact loading conditions is extremely important since impact problems are directly related to design of these engineering structures. This research investigates the response of a closed-cell aluminium foam (CYMAT) subjected to dynamic loading using the finite element software ABAQUS/explicit. The aim of this research is to numerically investigate the material and structural properties of closed-cell aluminium foam under impact loading conditions with interest in shock propagation and its effects on cell wall deformation. A μ-CT based 3D foam geometry is developed to simulate the local cell collapse behaviours. A number of numerical techniques are applied for modelling the crush behaviour of aluminium foam to obtain the more accurate results. The simulation results are compared with experimental data. Comparison of the results shows a good correlation between the experimental results and numerical predictions.

  15. Calculation of fluid (steam) hammer loading to piping systems by the response spectrum method

    International Nuclear Information System (INIS)

    Krause, G.; Schrader, W.; Leimbach, K.R.

    1983-01-01

    Today computations of fluid and steam hammer loading to piping systems are usually performed as a time-history analysis in which the transient pressure forces act as external excitations. For practical purposes it is desirable to be able to treat fluid hammer loading using the response spectrum method similarily as loads from external events. Two advantages arise from the use of spectra in the analysis of piping systems subjected to dynamic force excitations. Firstly, the response spectrum method is much less sensitive to model idealization than the time-history method. Secondly, computational efforts are reduced. In this paper the algorithm for the treatment of force excitations through the modal response spectrum method is briefly presented. The effect of the residuum accounting for higher modes which are not part of the modal decomposition is considered. In particular various methods of superposition of the responses of the dynamic forces and of the modes are investigated. Results and comparisons are presented of several response spectrum analyses and time-history analyses. (orig.)

  16. Vertical axis wind turbine drive train transient dynamics

    Science.gov (United States)

    Clauss, D. B.; Carne, T. G.

    1982-01-01

    Start up of a vertical axis wind turbine causes transient torque oscillations in the drive train with peak torques which may be over two and one half times the rated torque of the turbine. A computer code, based on a lumped parameter model of the drive train, was developed and tested for the low cost 17 meter turbine; the results show excellent agreement with field data. The code was used to predict the effect of a slip clutch on transient torque oscillations. It was demonstrated that a slip clutch located between the motor and brake can reduce peak torques by thirty eight percent.

  17. Transient behavior of flare-associated solar wind. II - Gas dynamics in a nonradial open field region

    Science.gov (United States)

    Nagai, F.

    1984-01-01

    Transient behavior of flare-associated solar wind in the nonradial open field region is numerically investigated, taking into account the thermal and dynamical coupling between the chromosphere and the corona. A realistic steady solar wind is constructed which passes through the inner X-type critical point in the rapidly diverging region. The wind speed shows a local maximum at the middle, O-type, critical point. The wind's density and pressure distributions decrease abruptly in the rapidly diverging region of the flow tube. The transient behavior of the wind following flare energy deposition includes ascending and descending conduction fronts. Thermal instability occurs in the lower corona, and ascending material flows out through the throat after the flare energy input ceases. A local density distribution peak is generated at the shock front due to the pressure deficit just behind the shock front.

  18. Transient analysis of the new Cold Source at the FRM-II

    International Nuclear Information System (INIS)

    Gutsmiedl, E.; Posselt, H.; Scheuer, A.

    2003-01-01

    The new Cold Source (CNS) at the FRM-II research reactor is completely installed. This paper reports on the results of the transient analysis in the design status for this facility for producing cold neutrons for neutron experiments, the implementation of the results in the design of the mechanical components, the measurements at the cold tests and the comparison with the data of the transient analysis. The important load cases are fixed in the system description and the design data sheet of the CNS. A transient analysis was done with the computer program ESATAN, the nodal configuration was identical with the planned system of the CNS and the boundary conditions were chosen so, that conservative results can be expected. The following transients of the load cases in the piping system behind the inpile part 1) normal storage of D 2 at the hydride storage vessel 2) breakdown of cooling system of the CNS and transfer of D 2 to the buffer tank 3) rapid charge of D 2 to the buffer tank with break of the insulation vacuum and flooding of Neon 4) reloading of the D 2 from the buffer tank to the D 2 hydride storage vessel were calculated. Additionally the temperature distribution for these transients in the connecting flanges of the systems to the inpile part were analysed. The temperature distributions in the flange region were take into account for the strength calculation of the flange construction. The chosen construction shows allowable values and a leak tight flange connection for the load cases. The piping system was designed to the lowest expected temperatures. The load cases in the moderator tank were take into account in the stress analysis and the fatigue analysis of the vacuum vessel and the moderator vessel. The results shows allowable stresses. The results shows that a transient analysis is necessary and helpful for good design of the CNS. (author)

  19. Concentration dependent carriers dynamics in CsPbBr3 perovskite nanocrystals film with transient grating

    Science.gov (United States)

    Wang, Yinghui; Wang, Yanting; Dev Verma, Sachin; Tan, Mingrui; Liu, Qinghui; Yuan, Qilin; Sui, Ning; Kang, Zhihui; Zhou, Qiang; Zhang, Han-Zhuang

    2017-05-01

    The concentration dependence of the carrier dynamics is a key parameter to describe the photo-physical properties of semiconductor films. Here, we investigate the carrier dynamics in the CsPbBr3 perovskite nanocrystal film by employing the transient grating (TG) technique with continuous bias light. The concentration of initial carriers is determined by the average number of photons per nanocrystals induced by pump light (⟨N⟩). The multi-body interaction would appear and accelerate the TG dynamics with ⟨N⟩. When ⟨N⟩ is more than 3.0, the TG dynamics slightly changes, which implies that the Auger recombination would be the highest order multi-body interaction in carrier recombination dynamics. The concentration of non-equilibrium carriers in the film is controlled by the average number of photons per nanocrystals excited by continuous bias light (⟨nne⟩). Increasing ⟨nne⟩ would improve the trapping-detrapping process by filling the trapping state, which would accelerate the carrier diffusion and add the complexity of the mono-molecular recombination mechanism. The results should be useful to further understand the mechanism of carrier dynamics in the CsPbBr3 perovskite nanocrystal film and of great importance for the operation of the corresponding optoelectronic devices.

  20. Dynamic loads on reactor vessel components by low pressure waves

    International Nuclear Information System (INIS)

    Benkert, J.; Mika, C.; Stegemann, D.; Valero, M.

    1978-01-01

    Starting from the conservation theorems for mass and impulses the code DRUWE has been developed enabling the calculation of dynamic loads of the reactor shell on the basis of simplified assumptions for the first period shortly after rupture. According to the RSK-guidelines it can be assumed that the whole weld size is opened within 15 msec. This time-dependent opening of the fractured plane can be taken into account in the computer program. The calculation is composed in a way that for a reactor shell devided into cross and angle sections the local, chronological pressure and strength curves, the total dynamic load as well as the moments acting on the fastenings of the reactor shell can be calculated. As input data only geometrical details concerning the concept of the pressure vessel and its components as well as the effective subcooling of the fluid are needed. By means of several parameters the program can be operated in a way that the results are available in form of listings or diagrams, respectively, but also as card pile for further examinations, e.g. strength analysis. (orig./RW) [de

  1. Test system to simulate transient overpower LMFBR cladding failure

    International Nuclear Information System (INIS)

    Barrus, H.G.; Feigenbutz, L.V.

    1981-01-01

    One of the HEDL programs has the objective to experimentally characterize fuel pin cladding failure due to cladding rupture or ripping. A new test system has been developed which simulates a transient mechanically-loaded fuel pin failure. In this new system the mechanical load is prototypic of a fuel pellet rapidly expanding against the cladding due to various causes such as fuel thermal expansion, fuel melting, and fuel swelling. This new test system is called the Fuel Cladding Mechanical Interaction Mandrel Loading Test (FCMI/MLT). The FCMI/MLT test system and the method used to rupture cladding specimens very rapidly to simulate a transient event are described. Also described is the automatic data acquisition and control system which is required to control the startup, operation and shutdown of the very fast tests, and needed to acquire and store large quantities of data in a short time

  2. Timing of transients: quantifying reaching times and transient behavior in complex systems

    Science.gov (United States)

    Kittel, Tim; Heitzig, Jobst; Webster, Kevin; Kurths, Jürgen

    2017-08-01

    In dynamical systems, one may ask how long it takes for a trajectory to reach the attractor, i.e. how long it spends in the transient phase. Although for a single trajectory the mathematically precise answer may be infinity, it still makes sense to compare different trajectories and quantify which of them approaches the attractor earlier. In this article, we categorize several problems of quantifying such transient times. To treat them, we propose two metrics, area under distance curve and regularized reaching time, that capture two complementary aspects of transient dynamics. The first, area under distance curve, is the distance of the trajectory to the attractor integrated over time. It measures which trajectories are ‘reluctant’, i.e. stay distant from the attractor for long, or ‘eager’ to approach it right away. Regularized reaching time, on the other hand, quantifies the additional time (positive or negative) that a trajectory starting at a chosen initial condition needs to approach the attractor as compared to some reference trajectory. A positive or negative value means that it approaches the attractor by this much ‘earlier’ or ‘later’ than the reference, respectively. We demonstrated their substantial potential for application with multiple paradigmatic examples uncovering new features.

  3. Nonlinear Diffusion and Transient Osmosis

    International Nuclear Information System (INIS)

    Igarashi, Akira; Rondoni, Lamberto; Botrugno, Antonio; Pizzi, Marco

    2011-01-01

    We investigate both analytically and numerically the concentration dynamics of a solution in two containers connected by a narrow and short channel, in which diffusion obeys a porous medium equation. We also consider the variation of the pressure in the containers due to the flow of matter in the channel. In particular, we identify a phenomenon, which depends on the transport of matter across nano-porous membranes, which we call ''transient osmosis . We find that nonlinear diffusion of the porous medium equation type allows numerous different osmotic-like phenomena, which are not present in the case of ordinary Fickian diffusion. Experimental results suggest one possible candidate for transiently osmotic processes. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  4. Analysis of piping response to thermal and operational transients

    International Nuclear Information System (INIS)

    Wang, C.Y.

    1987-01-01

    The reactor piping system is an extremely complex three-dimensional structure. Maintaining its structural integrity is essential to the safe operation of the reactor and the steam-supply system. In the safety analysis, various transient loads can be imposed on the piping which may cause plastic deformation and possible damage to the system, including those generated from hydrodynamic wave propagations, thermal and operational transients, as well as the seismic events. At Argonne National Laboratory (ANL), a three-dimensional (3-D) piping code, SHAPS, aimed for short-duration transients due to wave propagation, has been developed. Since 1984, the development work has been shifted to the long-duration accidents originating from the thermal and operational transient. As a result, a new version of the code, SHAPS-2, is being established. This paper describes many features related to this later development. To analyze piping response generated from thermal and operational transients, a 3-D implicit finite element algorithm has been developed for calculating the hoop, flexural, axial, and torsional deformations induced by the thermomechanical loads. The analysis appropriately accounts for stresses arising from the temperature dependence of the elastic material properties, the thermal expansion of the materials, and the changes in the temperature-dependent yield surface. Thermal softening, failure, strain rate, creep, and stress ratching can also be considered

  5. Tapping the energy storage potential in electric loads to deliver load following and regulation, with application to wind energy

    International Nuclear Information System (INIS)

    Callaway, Duncan S.

    2009-01-01

    This paper develops new methods to model and control the aggregated power demand from a population of thermostatically controlled loads, with the goal of delivering services such as regulation and load following. Previous work on direct load control focuses primarily on peak load shaving by directly interrupting power to loads. In contrast, the emphasis of this paper is on controlling loads to produce relatively short time scale responses (hourly to sub-hourly), and the control signal is applied by manipulation of temperature set points, possibly via programmable communicating thermostats or advanced metering infrastructure. To this end, the methods developed here leverage the existence of system diversity and use physically-based load models to inform the development of a new theoretical model that accurately predicts - even when the system is not in equilibrium - changes in load resulting from changes in thermostat temperature set points. Insight into the transient dynamics that result from set point changes is developed by deriving a new exact solution to a well-known hybrid state aggregated load model. The eigenvalues of the solution, which depend only on the thermal time constant of the loads under control, are shown to have a strong effect on the accuracy of the model. The paper also shows that load heterogeneity - generally something that must be assumed away in direct load control models - actually has a positive effect on model accuracy. System identification techniques are brought to bear on the problem, and it is shown that identified models perform only marginally better than the theoretical model. The paper concludes by deriving a minimum variance control law, and demonstrates its effectiveness in simulations wherein a population of loads is made to follow the output of a wind plant with very small changes in the nominal thermostat temperature set points.

  6. Prediction-based dynamic load-sharing heuristics

    Science.gov (United States)

    Goswami, Kumar K.; Devarakonda, Murthy; Iyer, Ravishankar K.

    1993-01-01

    The authors present dynamic load-sharing heuristics that use predicted resource requirements of processes to manage workloads in a distributed system. A previously developed statistical pattern-recognition method is employed for resource prediction. While nonprediction-based heuristics depend on a rapidly changing system status, the new heuristics depend on slowly changing program resource usage patterns. Furthermore, prediction-based heuristics can be more effective since they use future requirements rather than just the current system state. Four prediction-based heuristics, two centralized and two distributed, are presented. Using trace driven simulations, they are compared against random scheduling and two effective nonprediction based heuristics. Results show that the prediction-based centralized heuristics achieve up to 30 percent better response times than the nonprediction centralized heuristic, and that the prediction-based distributed heuristics achieve up to 50 percent improvements relative to their nonprediction counterpart.

  7. Evaluating transient performance of servo mechanisms by analysing stator current of PMSM

    Science.gov (United States)

    Zhang, Qing; Tan, Luyao; Xu, Guanghua

    2018-02-01

    Smooth running and rapid response are the desired performance goals for the transient motions of servo mechanisms. Because of the uncertain and unobservable transient behaviour of servo mechanisms, it is difficult to evaluate their transient performance. Under the effects of electromechanical coupling, the stator current signals of a permanent-magnet synchronous motor (PMSM) potentially contain the performance information regarding servo mechanisms in use. In this paper, a novel method based on analysing the stator current of the PMSM is proposed for quantifying the transient performance. First, a vector control model is constructed to simulate the stator current behaviour in the transient processes of consecutive speed changes, consecutive load changes, and intermittent start-stops. It is discovered that the amplitude and frequency of the stator current are modulated by the transient load torque and motor speed, respectively. The stator currents under different performance conditions are also simulated and compared. Then, the stator current is processed using a local means decomposition (LMD) algorithm to extract the instantaneous amplitude and instantaneous frequency. The sample entropy of the instantaneous amplitude, which reflects the complexity of the load torque variation, is calculated as a performance indicator of smooth running. The peak-to-peak value of the instantaneous frequency, which defines the range of the motor speed variation, is set as a performance indicator of rapid response. The proposed method is applied to both simulated data in an intermittent start-stops process and experimental data measured for a batch of servo turrets for turning lathes. The results show that the performance evaluations agree with the actual performance.

  8. Collapse mechanisms of metal foam matrix composites under static and dynamic loading conditions

    Energy Technology Data Exchange (ETDEWEB)

    Linul, Emanoil, E-mail: emanoil.linul@upt.ro [Department of Mechanics and Strength of Materials, Politehnica University of Timisoara, 1 Mihai Viteazu Avenue, 300 222 Timisoara (Romania); Marsavina, Liviu [Department of Mechanics and Strength of Materials, Politehnica University of Timisoara, 1 Mihai Viteazu Avenue, 300 222 Timisoara (Romania); Kováčik, Jaroslav [Institute of Materials and Machine Mechanics, Slovak Academy of Sciences, Dúbravská cesta 9, 845 13 Bratislava (Slovakia)

    2017-04-06

    The collapse mechanisms of metal foam matrix composites under static and dynamic loading conditions were experimentally and analytically investigated. Closed-cell aluminium foam AlSi10 with 325±10 kg/m{sup 3} density was used as core material, while stainless-steel-mesh is the faces materials. Prior to characterizing the composite sandwich structure, the stainless steel mesh face material and closed-cell aluminium foam were characterized by tensile testing and compression testing, respectively. Experimental tests were performed on sandwich beams using both High Speed Camera and Digital Image Correlation system for strain distribution. All experimental tests were performed at room temperature with constant crosshead speed of 1.67×10{sup −4} m/s for static tests and 2 m/s impact loading speed for dynamic tests. Two main deformation behaviours of investigated metal foam matrix composites were observed following post-failure collapse: face failure and core shear. It was showed that the initiation, propagation and interaction of failure modes depend on the type of loading, constituent material properties and geometrical parameters.

  9. An evaluation of analysis methodologies for predicting cleavage arrest of a deep crack in an RPV subjected to PTS loading conditions

    International Nuclear Information System (INIS)

    Keeney-Walker, J.; Bass, B.R.

    1992-01-01

    Several calculational procedures are compared for predicting cleavage arrest of a deep crack in the wall of a prototypical reactor pressure vessel (RPV) subjected to pressurized-thermal-shock (PTS) types of loading conditions. Three procedures examined in this study utilized the following models: (1) a static finite-element model (full bending); (2) a radially constrained static model; and (3) a thermoelastic dynamic finite-element model. A PTS transient loading condition was selected that produced a deep arrest of an axially-oriented initially shallow crack according to calculational results obtained from the static (full-bending) model. Results from the two static models were compared with those generated from the detailed thermoelastic dynamic finite-element analysis. The dynamic analyses modeled cleavage-crack propagation using node-release technique and an application-mode methodology based on dynamic fracture toughness curves generated from measured data. Comparisons presented here indicate that the degree to which dynamic solutions can be approximated by static models is highly dependent on several factors, including the material dynamic fracture curves and the propensity for cleavage reinitiation of the arrested crack under PTS loading conditions. Additional work is required to develop and validate a satisfactory dynamic fracture toughness model applicable to postcleavage arrest conditions in an RPV

  10. 3D analysis of the gas dynamic loads in the KKB containment resulting from combustion of radiolysis gas

    International Nuclear Information System (INIS)

    Kotchourko, A.; Breitung, W.; Dorofeev, S.; Ohlmeyer, H.

    2003-01-01

    The radiolysis gas explosion in the KKB power plant was recalculated in 3D simulations as followed: The total energy released was limited as far as possible. - Pressure generation and dispersion across the containment was calculated for three different initial energies. - Loads in the near field were simulated assuming the most probable total energy (about 14 MJ) and using three different models of the explosion process. The calculation with direct simulation of detonation inside the tube provided realistic results, according to the authors. - Transient local pressure and temperature loads were recorded in specified local points and evaluated in further damage analyses. The results showed that modern 3D flow and combustion calculations provide valuable information on pressure and temperature loads resulting from radiolysis gas reactions in big complex safety containments. (orig.) [de

  11. Computational methods for predicting the response of critical as-built infrastructure to dynamic loads (architectural surety)

    Energy Technology Data Exchange (ETDEWEB)

    Preece, D.S.; Weatherby, J.R.; Attaway, S.W.; Swegle, J.W.; Matalucci, R.V.

    1998-06-01

    Coupled blast-structural computational simulations using supercomputer capabilities will significantly advance the understanding of how complex structures respond under dynamic loads caused by explosives and earthquakes, an understanding with application to the surety of both federal and nonfederal buildings. Simulation of the effects of explosives on structures is a challenge because the explosive response can best be simulated using Eulerian computational techniques and structural behavior is best modeled using Lagrangian methods. Due to the different methodologies of the two computational techniques and code architecture requirements, they are usually implemented in different computer programs. Explosive and structure modeling in two different codes make it difficult or next to impossible to do coupled explosive/structure interaction simulations. Sandia National Laboratories has developed two techniques for solving this problem. The first is called Smoothed Particle Hydrodynamics (SPH), a relatively new gridless method comparable to Eulerian, that is especially suited for treating liquids and gases such as those produced by an explosive. The SPH capability has been fully implemented into the transient dynamics finite element (Lagrangian) codes PRONTO-2D and -3D. A PRONTO-3D/SPH simulation of the effect of a blast on a protective-wall barrier is presented in this paper. The second technique employed at Sandia National Laboratories uses a relatively new code called ALEGRA which is an ALE (Arbitrary Lagrangian-Eulerian) wave code with specific emphasis on large deformation and shock propagation. ALEGRA is capable of solving many shock-wave physics problems but it is especially suited for modeling problems involving the interaction of decoupled explosives with structures.

  12. Computer simulation of yielding supports under static and short-term dynamic load

    Directory of Open Access Journals (Sweden)

    Kumpyak Oleg

    2018-01-01

    Full Text Available Dynamic impacts that became frequent lately cause large human and economic losses, and their prevention methods are not always effective and reasonable. The given research aims at studying the way of enhancing explosion safety of building structures by means of yielding supports. The paper presents results of numerical studies of strength and deformation property of yielding supports in the shape of annular tubes under static and short-term dynamic loading. The degree of influence of yielding supports was assessed taking into account three peculiar stages of deformation: elastic; elasto-plastic; and elasto-plastic with hardening. The methodology for numerical studies performance was described using finite element analysis with program software Ansys Mechanical v17.2. It was established that rigidity of yielding supports influences significantly their stress-strain state. The research determined that with the increase in deformable elements rigidity dependence between load and deformation of the support in elastic and plastic stages have linear character. Significant reduction of the dynamic response and increase in deformation time of yielding supports were observed due to increasing the plastic component. Therefore, it allows assuming on possibility of their application as supporting units in RC beams.

  13. AN INVESTIGATION TO RESOLVE THE INTERACTION BETWEEN FUEL CELL, POWER CONDITIONING SYSTEM AND APPLICATION LOADS

    Energy Technology Data Exchange (ETDEWEB)

    Sudip K. Mazumder; Chuck McKintyre; Dan Herbison; Doug Nelson; Comas Haynes; Michael von Spakovsky; Joseph Hartvigsen; S. Elangovan

    2003-11-03

    nonlinear models of the SOFC stack subsystem (SOFCSS), the power-electronics subsystem (PES), and the BOPS. Such an approach leads to robust and comprehensive electrical, electrochemical, thermodynamic, kinetic, chemical, and geometric models of the SOFSS, PES and application loads, and BOPS. A comprehensive methodology to resolve interactions among SOFCSS, PES and application loads and to investigate the impacts of the fast- and slow-scale dynamics of the power-conditioning system (PCS) on the SOFCSS has been developed by this team. Parametric studies on SOFCSS have been performed and the effects of current ripple and load transients on SOFC material properties are investigated. These results are used to gain insights into the long-term performance and reliability of the SOFCSS. Based on this analysis, a novel, efficient, and reliable PES for SOFC has been developed. Impacts of SOFC PCS control techniques on the transient responses, flow parameters, and current densities have also been studied and a novel nonlinear hybrid controller for single/parallel DC-DC converter has been developed.

  14. Phase change energy storage for solar dynamic power systems

    Science.gov (United States)

    Chiaramonte, F. P.; Taylor, J. D.

    1992-01-01

    This paper presents the results of a transient computer simulation that was developed to study phase change energy storage techniques for Space Station Freedom (SSF) solar dynamic (SD) power systems. Such SD systems may be used in future growth SSF configurations. Two solar dynamic options are considered in this paper: Brayton and Rankine. Model elements consist of a single node receiver and concentrator, and takes into account overall heat engine efficiency and power distribution characteristics. The simulation not only computes the energy stored in the receiver phase change material (PCM), but also the amount of the PCM required for various combinations of load demands and power system mission constraints. For a solar dynamic power system in low earth orbit, the amount of stored PCM energy is calculated by balancing the solar energy input and the energy consumed by the loads corrected by an overall system efficiency. The model assumes an average 75 kW SD power system load profile which is connected to user loads via dedicated power distribution channels. The model then calculates the stored energy in the receiver and subsequently estimates the quantity of PCM necessary to meet peaking and contingency requirements. The model can also be used to conduct trade studies on the performance of SD power systems using different storage materials.

  15. Additional 5 kWe thermoelectric system temperature transients

    International Nuclear Information System (INIS)

    Halfen, F.J.

    1972-01-01

    Several additional system transients have been calculated for the 5 kW(e) TE system and are reported in this document. They include a startup transient with a reactivity rate of 0.005 cents/sec, several startup accidents, a step reactivity insertion at full power and a loss of electrical load. These data are intended for input to system design analyses and for possible use in the protected accident section of the safety report. (U.S.)

  16. A new strategy for transient stability using augmented generator control and local dynamic braking

    Energy Technology Data Exchange (ETDEWEB)

    Dorsey, J; Jiang, H; Habetler, T [Georgia Inst. of Tech., Atlanta, GA (United States); Qu, Z [University of Central Florida, Orlando, FL (United States)

    1994-12-31

    A decentralized automatic control strategy for significantly improving the transient stability of a large power system is introduced. The strategy combines local dynamic braking and a straightforward augmentation of the existing turbine / governor control system that uses only local feedback. The brake resistor, which employs thick film, metal oxide technology, has no inductance and is of very low resistance, allowing its use during fault to show a generator`s acceleration. Simulation results using the 39 Bus New England system show that the strategy dramatically increases the global stability of a power system. (author) 15 refs., 7 figs., 1 tab.

  17. A free-piston Stirling engine/linear alternator controls and load interaction test facility

    Science.gov (United States)

    Rauch, Jeffrey S.; Kankam, M. David; Santiago, Walter; Madi, Frank J.

    1992-01-01

    A test facility at LeRC was assembled for evaluating free-piston Stirling engine/linear alternator control options, and interaction with various electrical loads. This facility is based on a 'SPIKE' engine/alternator. The engine/alternator, a multi-purpose load system, a digital computer based load and facility control, and a data acquisition system with both steady-periodic and transient capability are described. Preliminary steady-periodic results are included for several operating modes of a digital AC parasitic load control. Preliminary results on the transient response to switching a resistive AC user load are discussed.

  18. Evaluation of MOSTAS computer code for predicting dynamic loads in two bladed wind turbines

    Science.gov (United States)

    Kaza, K. R. V.; Janetzke, D. C.; Sullivan, T. L.

    1979-01-01

    Calculated dynamic blade loads were compared with measured loads over a range of yaw stiffnesses of the DOE/NASA Mod-O wind turbine to evaluate the performance of two versions of the MOSTAS computer code. The first version uses a time-averaged coefficient approximation in conjunction with a multi-blade coordinate transformation for two bladed rotors to solve the equations of motion by standard eigenanalysis. The second version accounts for periodic coefficients while solving the equations by a time history integration. A hypothetical three-degree of freedom dynamic model was investigated. The exact equations of motion of this model were solved using the Floquet-Lipunov method. The equations with time-averaged coefficients were solved by standard eigenanalysis.

  19. Numerical methods in dynamic fracture mechanics

    International Nuclear Information System (INIS)

    Beskos, D.E.

    1987-01-01

    A review of numerical methods for the solution of dynamic problems of fracture mechanics is presented. Finite difference, finite element and boundary element methods as applied to linear elastic or viscoelastic and non-linear elastoplastic or elastoviscoplastic dynamic fracture mechanics problems are described and critically evaluated. Both cases of stationary cracks and rapidly propagating cracks of simple I, II, III or mixed modes are considered. Harmonically varying with time or general transient dynamic disturbances in the form of external loading or incident waves are taken into account. Determination of the dynamic stress intensity factor for stationary cracks or moving cracks with known velocity history as well as determination of the crack-tip propagation history for given dynamic fracture toughness versus crack velocity relation are described and illustrated by means of certain representative examples. Finally, a brief assessment of the present state of knowledge is made and research needs are identified

  20. Dynamics of defect-loaded grain boundary under shear deformation in alpha iron

    Science.gov (United States)

    Yang, L.; Zhou, H. L.; Liu, H.; Gao, F.; Zu, X. T.; Peng, S. M.; Long, X. G.; Zhou, X. S.

    2018-02-01

    Two symmetric tilt grain boundaries (GBs) (Σ3〈110〉{112} and Σ11〈110〉{332}) in alpha iron were performed to investigate the dynamics of defect-loaded GBs under shear deformation. The results show that the loaded self-interstitial atoms (SIAs) reduce the critical stress of the coupled GB motion in the Σ3 GB, but increase the critical stress in the Σ11 GB. The loaded SIAs in the Σ3 GB easily form 〈111〉 clusters and remain in the bulk when the GB moves away. However, the SIAs move along with the Σ11 GB and combine with the vacancies in the bulk, leading to the defect self-healing. The helium (He) atoms loaded into the GBs significantly affect the coupled GB motion. Once He clusters emit interstitials, the Σ11 GB carries those interstitials away but the Σ3 does not. The loaded He atoms reduce the critical stress of the Σ3 GB, but increase the critical stress of the Σ11 GB.