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The tremendous growth of wireless technologies has introduced the potential of continuous service adaptation to the users' needs by giving them the ability to be able to select and access the proper network based on different criteria. Moreover, next generation wireless networks have been designed to provide support for multimedia services, with different traffic characteristics and different Quality of Service (QoS) guarantees. However, the expansion of Wireless Local Area Networks (WLANs) and Worldwide Interoperability for Microwave Access (WiMAX) networks poses new research era in the decision of the access network selection. In this paper, the existing access network selection schemes are classified into three categories: the network-centric, the user-centric and the collaborative sche...

DEFF Research Database (Denmark)

Introducing intelligence by means of cognition for managing, protecting, processing, and delivering of information in mobile communication systems is the way towards ubiquitous, converged and secure communications. In this context, this paper introduces the concept of quality of information (QoI). QoI means QoS while all the requirements for dependability, security, privacy and trust are satisfied at the highest possible level. This work proposes and describes an approach to network monitoring in a heterogeneous communication environment based on use of cognitive techniques and learning predictive algorithms (e.g., fuzzy logic). These methodologies are used to create an autonomy in the decision making process that is based on the calculation of key performance indicators (KPIs), which in their turn would trigger the needed radio resource management algorithms. The expected output is an improved network performance in terms ...

Science.gov (United States)

Recent trends in distributed real-time and embedded (DRE) systems motivate the development of tactical information management capabilities that ensure the right information is delivered to the right place at the right time to satisfy quality of service (QoS) requirements in heterogeneous environments. A promising approach to building and evolving large-scale and long-lived tactical information management systems are standards-based QoS-enabled publish/subscribe (pub/sub) platforms that enable applications to communicate by publishing information they have and subscribing to information they need in a timely manner. Since there is little existing evaluation of how well these platforms meet the performance needs of tactical information management, this paper provides two contributions: (1) it describes three common architectures for the OMG Data Distribution Service (DDS), which is a QoS-enabled pub/sub platform standard, and (2) it evaluates ...

Science.gov (United States)

... of the cycle shows that the separation area ea. ... with suitable flow solvers based on the Reynolds ... AGARD 75th Fluid Dynamics Panel Meeting and ...

UK PubMed Central (United Kingdom)

Specific criteria have been developed based on computerized dynamic posturography (CDP) to assist clinicians in identifying patients with psychogenic balance problems (Cyr and Cevette, Full Text Available

UK PubMed Central (United Kingdom)

The sequence-dependent structural variability and conformational dynamics of DNA play pivotal roles in many biological milieus, such as in the site-specific binding of transcription factors to target...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

A stable power system stabilizer (PSS) based on the inverse dynamics of the controlled system using an artificial neural network (ANN) is suggested to enhance the dynamic performances of a power system. First, an output feedback control law is driven with some conditions satisfied, which guarantees the internal stability and robustness against the asymptotically stable external disturbances. Then the control law is implemented using the inverse dynamics of the controlled plant. The inverse dynamics of the controlled plant is identified by an ANN, inverse dynamics neural network (IDNN), off-line. The pole-shifting technique and a scaling factor are introduced for the control system to meet the conditions for internal stability and robustness. The proposed controller is applied to a typical single-machine infinite-bus power system. Simulation results under various ...

Science.gov (United States)

... defense's weapons are Space-based kinetic-kill vehicles ... I ti I obtained by dividing the weapons as ... of the optimal weapon-arge assigntments and ...

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The applications of neutron reflectometry to study dynamic phenomena at surface and interfaces have been restricted so far. This was mainly due to the low intensity of neutron sources, but now high-intensity spallation neutron sources are under construction in Japan (J-PARC) and US (SNS). We are planning to install a spin-echo option on the J-PARC neutron reflectometer with horizontal sample geometry for studies of dynamics of surfaces and interfaces. This option is based on the resonance spin-echo method and aimed at dynamics up to hundreds of nanoseconds. In this contribution, the plan and status of development are introduced together with the principle and characteristics of this option.

CERN Document Server

Constrained quantum dynamics is used to propose a nonlinear dynamical equation for pure states of a generalized coarse-grained system. The relevant constraint is given either by the generalized purity or by the generalized invariant fluctuation, and the coarse-grained pure states correspond to the generalized coherent i.e. generalized nonentangled states. Open system model of the coarse-graining is discussed. It is shown that in this model and in the weak coupling limit the constrained dynamical equations coincide with an equation for pointer states, based on Hilbert-Schmidt distance, that was previously suggested in the context of the decoherence theory.

Energy Technology Data Exchange (ETDEWEB)

This investigation concerns the nonlinear dynamics of heat transfer from a surface using an upstream eddy promoter. A numerical model is developed for the coupled fluid flow and heat transfer process based on a modified MacCormack scheme. Numerical simulations are carried out to determine the response and heat transfer enhancement due to the promoter. The average heat transfer from a cavity floor is seen to be increased by a factor of approximately five over the unpromoted'' flow. Another interesting feature of the study is the nonlinear viscous flow dynamics from the cylinder-wall interaction which differ significantly from the familiar cylinder-free stream patterns.

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This report describes the test of a dynamic phase compensation unit for a wind turbine with directly connected induction generators. The compensation unit is based on thyristor switched capacitors, where conventional wind turbine compensations use mechanical contactors to switch the capacitors. The influence on power quality analysed, and influence on component lifetime is discussed. Besides, simulation models in Matlab/Simulink are presented, including a flicker meter model. (au)

British Library Electronic Table of Contents (United Kingdom)

In this article, equations of motion of a manipulator are derived after consideration of the characteristics of the driving source. By considering a collision between a link and an object, and considering the active motion to absorb the kinetic energy of the object, the trajectories for saving energy are calculated by the iterative dynamic programming (IDP) method. The dynamic characteristics of manipulator control based on the trajectory for saving energy are also analyzed theoretically and investigated experimentally.

CERN Document Server

Today, component oriented middlewares are used to design, develop and deploy easily distributed applications, by ensuring the heterogeneity, interoperability, and reuse of the software modules, and the separation between the business code encapsulated in the components and the system code managed by the containers. Several standards answer this definition such as: CCM (CORBA Component Model), EJB (Enterprise Java Beans) and .Net. However these standards offer a limited and fixed number of system services, removing any possibility to add system services or to reconfigure dynamically the middleware. Our works propose mechanisms to add and to adapt dynamically the system services, based on a reconfiguration language which is dynamically adaptable to the need of the reconfiguration, and on a tool of dynamic reconfiguration, a prototype was achieved for the OpenCCM platform, that is an ...

UK PubMed Central (United Kingdom)

BackgroundEpilepsy is a common neurological disorder characterized by recurrent electrophysiological activities, known as seizures. Without the appropriate detection strategies,...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

A new model for computations is considered which combines the quantum computer with the chaotic dynamics amplifier, based on the logistic map. We discuss the satisfiability problem and argue that the problem can, in principle, be solved in polynomial time if one uses the new model for computations.

UK PubMed Central (United Kingdom)

An estimator for the load share parameters in an equal load-share model is derived based on observing k-component parallel systems of identical components that have a continuous...Full Text Available

International Nuclear Information System (INIS)

Russian 2008 p. 244 Russian Federation Artemov, SV Yarmukhamedov,

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The Dynamic Transmission Electron Microscope (DTEM) is introduced as a novel tool for in situ processing of materials. Examples of various types of dynamic studies outline the advantages and differences of laser-based heating in the DTEM in comparison to conventional (resistive) heating in situ TEM methods. We demonstrate various unique capabilities of the drive laser, namely, in situ processing of nanoscale materials, rapid and high temperature phase transformations, and controlled thermal activation of materials. These experiments would otherwise be impossible without the use of the DTEM drive laser. Thus, the potential of the DTEM to as a new technique to process and characterize the growth of a myriad of micro and nanostructures is demonstrated.

International Nuclear Information System (INIS)

Background vibration in a CANDU plant can be used to determine the dynamic characteristics of major items of equipment, such as calandria, the fuelling machines and the primary heat transport pumps. These dynamic characteristics can then be used to verify the seismic response of the equipment which, at present, is based on theoretical models only. The feasibility and basic theory of this new approach (which uses accelerations measured at several points on a structure and does not require knowledge of the source of excitation) was established in Phase I of the study. This report is based on Phase II in which the methods of analysis developed in Phase I were improved and verified experimentally. A Fast Fourier Transform (FFT) algorithm was incorporated and an interactive curve fitting technique was developed to obtain the dynamic characteristics in the form of natural frequencies, ...

Science.gov (United States)

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As part of a comprehensive simulation of a prototype locomotive propulsion system, a detailed model has been developed which predicts the dynamic response of an experimental 2-stroke, turbocharged and intercooled diesel engine. Engine fueling and brake torque are computed from regression equations derived from an extensive data base. Corrections are applied to the calculated steady-state torque to account for dynamic deviations of in-cylinder trapped air-fuel ratio from the steady-state value. The engine simulation accurately represents the operation of the turbo-charger, which is gear-driven at low turbocharger speeds, and freewheels through an overrunning clutch when exhaust energy accelerates the turbocharger beyond its geared speed. Engine fueling level, ie, rack, is determined from a dynamic simulation of an electrohydraulic governor which responds to the difference between the desired and the ...

CERN Document Server

Involving effects of media, opinion leader and other agents on the opinion of individuals of market society, a trader based model is developed and utilized to simulate price via supply and demand. Pronounced effects are considered with several weights and some personal differences between traders are taken into account. Resulting time series and probabilty distribution function involving a power law for price come out similar to the real ones.

International Nuclear Information System (INIS)

This work aims at improving the understanding of the dynamics of a Free Electron Laser (FEL) based on a storage ring. A new phenomenon of saturation by the electron bunch transverse dimensions is pointed out, during the FEL operation with a magnetic optics ''low emittance''. A part of this thesis work concerns the study of the longitudinal dynamics of the FEL depending on a parameter: the detuning between the pass frequency of the electrons and the back and return frequency of the laser pulse in the optical cavity. This study shows that the FEL presents a pulsed or a steady state behavior depending on the detuning. Besides, a spectro-temporal behavior of the FEL is pointed out showing the FEL pulse substructures and holes in the spectrum. Another part of this work concerns the response of the resonant FEL system, when a perturbation is applied on the gain. Under the effect of a modulation, the FEL can present a periodic or ...

CERN Document Server

Consider the flow of a thin layer of non-Newtonian fluid over a solid surface. I model the case of a viscosity that depends nonlinearly on the shear-rate; power law fluids are an important example, but the analysis here is for general nonlinear dependence. The modelling allows for large changes in film thickness provided the changes occur over a large enough lateral length scale. Modifying the surface boundary condition for tangential stress forms an accessible base for the analysis where flow with constant shear is a neutral critical mode, in addition to a mode representing conservation of fluid. Perturbatively removing the modification then constructs a model for the coupled dynamics of the fluid depth and the lateral momentum. For example, the results model the dynamics of gravity currents of non-Newtonian fluids even when the flow is not very slow.

Energy Technology Data Exchange (ETDEWEB)

We develop a continuum description for the axial segregation of granular materials in a long rotating drum based on the dynamics of the thin near-surface granular flow coupled to bulk flow. The equations of motion are reduced to the one-dimensional system for two local variables only, the concentration difference and the dynamic angle of repose, or the average slope of the free surface. The parameters of the system are established from comparison with experimental data. The resulting system describes both initial transient traveling wave dynamics and the formation of quasi-stationary bands of segregated materials. A long-term evolution proceeds through slow logarithmic coarsening of the band structure which is analogous to the spinoidal decomposition described by the Cahn-Hilliard equation. {copyright} {ital 1999} {ital The American Physical Society}

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An analytical model is proposed for the design and simulation of in-situ fracture of deep oil sand formations. This model is based on the finite element variational principle in conjunction with special empirical modules to characterize in-situ oil sands behavior. A computer code by the name of SANFRAC was developed to handle the dynamic fracture of formations induced by explosives. Simulation of hydraulic fracture processes can be treated by the same code as special cases using the quasi-static analysis. Numerical case studies by the SANFRAC code indicate that extensive horizontal fracture can be achieved by dynamic loads with proper fracture starters configured at the injection well. The unique advantage of the dynamic fracturing technique over the hydraulic fracture methods is also demonstrated by these studies.

CERN Document Server

We present a dynamical spectral model for Large Eddy Simulation of the incompressible magnetohydrodynamic (MHD) equations based on the Eddy Damped Quasi Normal Markovian approximation. This model extends classical spectral Large Eddy Simulations for the Navier-Stokes equations to incorporate general (non Kolmogorovian) spectra as well as eddy noise. We derive the model for MHD and show that introducing a new eddy-damping time for the dynamics of spectral tensors in the absence of equipartition between the velocity and magnetic fields leads to better agreement with direct numerical simulations, an important point for dynamo computations.

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Numerical simulation of dynamic fracture of concrete slabs, impacted by steel projectiles, was carried out in this study. The concrete response was described by a continuum damage model. This continuum damage model was originally developed to study rock fragmentation and was modified in the present study with an emphasis on the post-limit structural response. The model was implemented into a transient dynamic explicit finite element code LS-DYNA2D and the code was then used for the numerical simulations. The specific impact configuration of this study follows the experiment series conducted by Hanchak et al. Comparisons between calculated results and measured data were made. Good agreements were found.

Energy Technology Data Exchange (ETDEWEB)

The authors use a Glauber multiple-collision model to examine the dynamics of nucleus-nucleus collisions. The model introduces a stopping law, which describes how a baryon loses energy in a baryon-baryon collision, and a particle production law, which is based on the baryon energy loss. The model gives results on the longitudinal energy loss which compare well with the recent WA80 experimental data for /sup 16/O on various targets at 60 and 200 GeV per nucleon. The stopping law that is needed to fit the experimental zero-degree spectra reveals that the degree of stopping in these high-energy nuclear collisions is high.

Science.gov (United States)

Optimization is a powerful paradigm for expressing and solving problems in a wide range of areas, and has been successfully applied to many vision problems. Discrete optimization techniques are especially interesting since, by carefully exploiting problem structure, they often provide nontrivial guarantees concerning solution quality. In this paper, we review dynamic programming and graph algorithms, and discuss representative examples of how these discrete optimization techniques have been applied to some classical vision problems. We focus on the low-level vision problem of stereo, the mid-level problem of interactive object segmentation, and the high-level problem of model-based recognition. PMID:20660950

Science.gov (United States)

The dynamic response characteristics of the vertical axis wind turbine (VAWT) rotor are important factors governing the safety and fatigue life of VAWT systems. The principal problems are the determination of critical rotor speeds (resonances) and the assessment of forced vibration response amplitudes. The solution to these problems is complicated by centrifugal and Coriolis effects which can have substantial influence on rotor resonant frequencies and mode shapes. The primary tools now in use for rotor analysis are described and discussed. These tools include a lumped spring mass model (VAWTDYN) and also finite-element based approaches. The accuracy and completeness of current capabilities are also discussed.

International Nuclear Information System (INIS)

An artificial neural network can be used as an intelligent controller to control non-linear, dynamic system through learning. It can easily accommodate non-linearities and time dependencies. Most common multi-layer feed-forward neural networks have drawbacks of large number of neurons and hidden layers required to deal with complex problems and require large training time. To overcome these drawbacks, a generalized neuron based non-linear controller has been developed and illustrated as a power system stabilizer. Studies on a five-machine power system show that the proposed controller can significantly improve the dynamic performance and provide good damping of the power system over a wide operating range.

British Library Electronic Table of Contents (United Kingdom)

Abstract A one step method was used to prepare stable aqueous nanocomposite dispersions based on cellulose whiskers extracted from the rachis of the date palm tree and a poly(styrene co 2 ethyl hexylacrylate) copolymer via miniemulsion polymerization. A reactive silane, i.e., methacryloxypropyl triethoxysilane was added to stabilize the dispersion and favor the anchoring of the whiskers on polymer particles. Dynamic light scattering was used to study the effect of the silane and whiskers contents on the average particle size of the polymer. Nanocomposites materials were prepared from these dispersions using a casting/evaporation method. The effect of the silane and whiskers contents on the thermal and mechanical properties were studied using differential scanning calorimetry and dynamic me...

CERN Document Server

Standard micro-economics concentrate on the description of markets but is seldom interested in production. Several economists discussed the concept of a firm, as opposed to an open labour market where entrepreneurs would recrute workers on the occasion of each business opportunity. Coase \\cite{Coase} is one of them, who explains the existence of firms as institution because they reduce the transaction costs with respect to an open labour market. Whatever the rationale proposed by economists to account for the existence of firms, their perspective is based on efficiency and cost analysis. Little attention is paid to the dynamics of emergence and evolution of firms. The aim of the present manuscript is to check the global dynamical properties of a very simple model based on bounded rationality and reinforcement learning. Workers and managers are localised on a lattice and they choose collaborators on the ...

CERN Document Server

n an early approach, we proposed a kinetic model with multiple translational temperature [K. Xu, H. Liu and J. Jiang, Phys. Fluids {\\bf 19}, 016101 (2007)], to simulate non-equilibrium flows. In this paper, instead of using three temperatures in $x-$, $y-$, and $z$-directions, we are going to further define the translational temperature as a second-order symmetric tensor. Based on a multiple stage BGK-type collision model and the Chapman-Enskog expansion, the corresponding macroscopic gas dynamics equations in three-dimensional space will be derived. The zeroth-order expansion gives the 10 moment closure equations of Levermore [C.D. Levermore, J. Stat. Phys {\\bf 83}, pp.1021 (1996)]. To the 1st-order expansion, the derived gas dynamic equations can be considered as a regularization of Levermore's 10 moments equations. The new gas dynamic equations have the same structure as the Navier-Stokes ...

Energy Technology Data Exchange (ETDEWEB)

An experimental apparatus has been built that allows direct measurement of the oil film thickness in a bearing that is subjected to dynamic loads and shaft speeds representative of those occurring in automotive engine connecting rod, big-end bearings. Dynamic motion of the shaft, relative to the bearing, is measured as a function of shaft rotational angle, using non-contact, eddy-current probes. A computer based data acquisition system is used to measure, record, and analyze the journal position in the bearing. The test bearing is 63.5 mm in diameter by 25.4 mm long, and is loaded using a servo-hydraulic actuator rated at 98.3 kN. The journal has an operating speed of 500 to 3800 rpm. The actuator is controlled by a computer-generated waveform that can duplicate load profiles developed by various engines operating at a wide range of conditions. Measurements taken with the shaft statically loaded show excellent agreement ...

CERN Document Server

Two-tier networks, comprising a conventional cellular network overlaid with shorter range hotspots (e.g. femtocells, distributed antennas, or wired relays), offer an economically viable way to improve cellular system capacity. The capacity-limiting factor in such networks is interference. The cross-tier interference between macrocells and femtocells can suffocate the capacity due to the near-far problem, so in practice hotspots should use a different frequency channel than the potentially nearby high-power macrocell users. Centralized or coordinated frequency planning, which is difficult and inefficient even in conventional cellular networks, is all but impossible in a two-tier network. This paper proposes and analyzes an optimum decentralized spectrum allocation policy for two-tier networks that employ frequency division multiple access (including OFDMA). The proposed allocation is optimal in terms of Area Spectral Efficiency (ASE), and is subjected to a sensible Quality of Service ...

International Nuclear Information System (INIS)

This paper presents a practical case study on the dynamic stability of the Saudi Electricity Company (SEC) power system and its effect on increasing power transfer limit of the interconnection between Eastern Operating Area (SEC-EOA). The problem of optimal tuning of the power system stabilizer parameters was converted into optimization problem wth eigenvalue-based objective functions, which was then solved by genetic algorithms. In this regard, two eigenvalue-based objective functions were considered and the problem is solved using real-coded genetic algorithm (RCGA). The effectiveness of the suggested technique to enhance the power system dynamic stability and to extend the power transfer capability limit of the SEC-EOA and the SEC-EOA power system was verified through a comprehensive eigenvalue analysis and time-domain nonlinear simulation. The results also indicated that the proposed tuning schemes ...

Energy Technology Data Exchange (ETDEWEB)

A decoupled characteristic between the damping of a specific swing mode and the stabilizer gain of the corresponding machine in multimachine power systems is identified. Using this decoupled characteristic a power system stabilizer (PSS) synthesis approach which is based on the phase compensation concept is verified on a 9-machine system and the dynamic performance of this system is significantly improved. This method is proved to be effective, simple and it can provide useful guidance for the PSS field tuning.

Energy Technology Data Exchange (ETDEWEB)

A new multigrid algorithm based on the method of self-correction for the solution of elliptic problems is described. The method exploits information contained in the residual to dynamically modify the source term (right-hand side) of the elliptic problem. It is shown that the self-correcting solver is more efficient at damping the short wavelength modes of the algebraic error than its standard equivalent. When used in conjunction with a multigrid method, the resulting solver displays an improved convergence rate with no additional computational work.

International Nuclear Information System (INIS)

In this study, a probabilistic seismic risk analysis of the Wolsung NPP containment building was performed by a seismic hazard analysis and a seismic fragility analysis based on the nonlinear dynamic time-history analyses. The conventional seismic fragility analysis of the safety related structures in a NPP have been performed by using the linear elastic analysis results. The probabilistic seismic risk of the containment building was 5.19e-8.

British Library Electronic Table of Contents (United Kingdom)

Phonon relaxation and internal friction in kaolin-and bentonite-filled PVC composites are studied. By varying the temperature and/or content of the ultrafine mineral filler in the PVC, one can control the contribution from phonon viscosity, damping force, and the effect of viscosity into the energy dissipation of ultrasonic oscillations in the MHz frequency interval. The dynamic character of the measurements makes it possible to differentiate between relaxation phenomena in the composites and to suggest methods for their controlled changes.

International Nuclear Information System (INIS)

The image processing system for the dynamic neutron radiography has been developed. It is based on the hardware subset, composed by the method of the pipe-line and use of algorithm of local statistics. The processing speed per one pixel is shorter than 100 n sec and video-rate processing can be executed on it. Some image processes for improving the quality of the real-time neutron image, noise reduction and contrast stretching would be attempted by the use of this system. (author).

Energy Technology Data Exchange (ETDEWEB)

With the help of the symmetry at the P point, we have determined the relations between the force constants and the moduli of elasticity for A-15 compounds. Based on these relations, a semi-experimental method for the study of the lattice dynamic behaviors of A-15 compounds is developed. Numerical calculations of the phonon spectrum of Nb/sub 3/Sn and its temperature dependence have been made, and they are in good agreement with the experimental data.

CERN Document Server

An approach to solving the problem of managerial control quality improvement corporate information-calculating networks (CICN) is proposed. The approach is based on the concept of a flexible toolkit. A macro-model, system-science and system-engineering models of an intelligent managerial control system (IMCS) for CICN development are considered as well as its dynamics. The practical opportunity of IMCS implementation is assessed. (5 refs).

Science.gov (United States)

In this paper the thermal equilibrium number of solitons in DNA as a function of absolute temperature and the number of base pairs is calculated. These calculations are effected by modeling DNA as a Toda lattice with parameters chosen to match experimentally measured properties of DNA. It is found that a significant number of solitons is generated at physiological temperature. 23 refs., 2 figs.

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The paper presents the integration of the SIMBAD space charge module in the UAL framework. SIMBAD is a Particle-in-Cell (PIC) code. Its 3-D Parallel approach features an optimized load balancing scheme based on a genetic algorithm. The UAL framework enhances the SIMBAD standalone version with the interactive ROOT-based analysis environment and an open catalog of accelerator algorithms. The composite package addresses complex high intensity beam dynamics and has been developed as part of the FAIR SIS 100 project.

CERN Document Server

The open source Scala language is a Java--based dynamic scripting, functional programming language. Moreover, this highly scalable scripting language lends itself well to building Cloud--based/deliverable Software as a Service (SaaS) online applications. Written by Lift Scala web framework founder and lead Dave Pollak, Beginning Scala takes a down--to--earth approach to teaching Scala that leads you through simple examples that can be combined to build complex, scalable systems and applications. This book introduces you to the Scala programming language and then guides you through Scala constr

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This work contains 27 chapters which cover recent advances in fracture mechanics applied to cement-based composites: concrete, reinforced concrete, and fiber reinforced concrete. The book, based on a NATO Advanced Study Institute, is a comprehensive survey of treating nonlinearity associated with crack growth in brittle materials such as cement composites, rocks and ice. The book is divided into 8 major themes: advances in nonlinear fracture mechanics; fracture processes; numerical modelling of fracture; experimental methods of determining fracture parameters; damage and continuum modelling; strain-rate and dynamic effects of crack propagation; stress-corrosion, time and temperature effects on fracture; and implications for concrete structures.

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Because the bridges over the Rio Grande were to be razed, the investigators were able to introduce simulated cracks in four stages of increasing length into the structure. This paper summarizes the results of ambient and conventional, measured-input, modal analyses, performed on the undamaged structure. Also summarized are the results of conventional modal analyses performed after each stage of damage had been introduced. These tests were intended to quantify the amount of damage necessary to produce changes in the global dynamic properties of the bridge and to form a data base that can be used by other investigators to develop damage identification algorithms. Conventional modal analysis identified changes in the global dynamic properties of the structure only after the final stage of a damage.

CERN Document Server

The auroras on Jupiter and Saturn can be studied with a high sensitivity and resolution by the Hubble Space Telescope (HST) ultraviolet (UV) and far-ultraviolet (FUV) Space Telescope spectrograph (STIS) and Advanced Camera for Surveys (ACS) instruments. We present results of automatic detection and segmentation of Jupiter's auroral emissions as observed by HST ACS instrument with VOronoi Image SEgmentation (VOISE). VOISE is a dynamic algorithm for partitioning the underlying pixel grid of an image into regions according to a prescribed homogeneity criterion. The algorithm consists of an iterative procedure that dynamically constructs a tessellation of the image plane based on a Voronoi Diagram, until the intensity of the underlying image within each region is classified as homogeneous. The computed tessellations allow the extraction of quantitative information about the auroral features such as mean intensity, latitudinal ...

Science.gov (United States)

A method for simplifying finite element models of structures having a beam-like global dynamical behaviour is presented. This method is based on the use of a general uniform beam finite element formulation. It takes into account both transverse shear effects and dynamical coupling between bending and torsion due to the fact that mass centres and shear centres do not always coincide. For that purpose, we develop a condensation method for reducing any shell model into an equivalent beam, as well as a technique for automatically identifying the corresponding set of beam parameters. The method is applied to several illustrate examples that demonstrate its ability to simplify finite element models for many kinds of sophisticated structures having a beam-like predominant behaviour.

CERN Document Server

In the paper we investigate a mathematical model describing the growth of tumor in the presence of immune response of a host organism. The dynamics of tumour and immune cells is based on the generic Michaelis-Menten kinetics describing interaction and competition between the tumour and the immune system. The appropriate phenomenological equation modeling cell-mediated immune surveillance against cancer is of the predator-prey form and within a given choice of parameters exhibits bistability. Under the influence of spontaneous weak fluctuations, the model may be analyzed in terms of a stochastic differential equation bearing the form of an overdamped Langevin-like dynamics in the external quasi-potential represented by a double well. We analyze properties of the system within the range of parameters for which the potential wells are of the same depth and when the additional perturbation describing a periodic treatment is ...

International Nuclear Information System (INIS)

Experience with the identification and tuning of exciter constants for a generating unit as the Second Nuclear Power Plant of Taiwan Power Company is reported. Field test is first performed on the excitation system with the generator open-circuited. Since the field test results differ from the computer simulation results using manufacturer's constants, the authors first modify the manufacturer's constants based on their previous experience to reach a preliminary set of parameters for the excitation system. Then a hybrid nonlinear simulation-sensitivity matrix method is developed to further refine the excitation system parameters. The exciter constants are tuned in order to give better dynamic response before a power system stabilizer is applied to the generator. Field tests are then performed in order to compare the dynamic response of the generator without and with power system stabilizer.

Energy Technology Data Exchange (ETDEWEB)

The dynamic response characteristics of the VAWT rotor are important factors governing the safety and fatique life of VAWT systems. The principal problems are the determination of critical rotor speeds (resonances) and the assessment of forced vibration response amplitudes. The solution to these problems is complicated by centrifugal and Coriolis effects which can have substantial influence on rotor resonant frequencies and mode shapes. This paper will describe and discuss the primary tools now in use at Sandia National Laboratories for rotor analysis. These tools include a lumped spring-mass model (VAWTDYN) and also finite-element based approaches. The discussion will center on the accuracy and completeness of current capabilities and plans for future research. As this paper is meant primarily to provide an overview, much of the detail is omitted and will be presented in a follow-on report.

CERN Document Server

A growing number of applications that generate massive streams of data need intelligent data processing and online analysis. Real-time surveillance systems, telecommunication systems, sensor networks and other dynamic environments are such examples. The imminent need for turning such data into useful information and knowledge augments the development of systems, algorithms and frameworks that address streaming challenges. The storage, querying and mining of such data sets are highly computationally challenging tasks. Mining data streams is concerned with extracting knowledge structures represented in models and patterns in non stopping streams of information. Generally, two main challenges are designing fast mining methods for data streams and need to promptly detect changing concepts and data distribution because of highly dynamic nature of data streams. The goal of this article is to analyze and classify the application of diverse data mining ...

Energy Technology Data Exchange (ETDEWEB)

A technique for designing an adaptive power system stabilizer is presented which improves the dynamic stability of power systems by effectively increasing the damping torque of the synchronous generator in the system. The proposed adaptive stabilizer is optimal in the sense of minimizing a specified performance condition. A characteristic feature of using a Lyapunov techniques is that it leads to stable adaptation loops. The dynamic responses following a step disturbance by digital simulations are obtained by means of three types of stabilizers: the conventional power system stabilizer, a frequency-response-based optimal adaptive stabilizer and the proposed Lyapunov stabilizer. Simulation results on a typical single-machine/infinite-bus system illustrate the superiority of the proposed technique. (author).

KoreaScience (Korea)

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Energy Technology Data Exchange (ETDEWEB)

Electromechanical oscillations of small magnitude and low frequency exist in the interconnected power system and often persist for long periods of time. Power system stabilizers (PSSs) are traditionally used to provide damping torque for the synchronous generators to suppress the oscillations by generating supplementary control signals for the generator excitation system. Numerous techniques have previously been proposed to design PSSs but many of them are synthesized based on a linearized model. This paper presents a nonlinear power system stabilizer based on synergetic control theory. Synergetic synthesis of the PSS is based fully on a simplified nonlinear model of the power system. The dynamic characteristics of the proposed PSS are studied in a typical single-machine infinite-bus power system and compared with the cases with a conventional PSS and without a PSS. Simulation results show the proposed ...

Energy Technology Data Exchange (ETDEWEB)

Dynamic behaviors of gaseous sulfur-containing compounds evolved from pyrolysis of six Chinese coals were studied in the temperature range of up to 800{sup o}C under N{sub 2} and H{sub 2}. The released amount of total sulfur-containing gases was traced by an online flame photometric detector (FPD). Simultaneously, the changes of different sulfur forms, including H{sub 2}S, SO{sub 2}, COS and CS{sub 2}, also were investigated using an online mass spectrometer (MS). FPD results show that the effect of H{sub 2} on gaseous sulfur evolved is complex, which promoted certain peak and suppresses other peaks. Based on the data from MS, it is suggested that a series of competitive reactions between active sulfur and other active matters during pyrolysis may impact on the sulfur form in gas phase. Interactions between active sulfur-containing intermediates and the coal matrix are attributed to be the main factor determining the ...

Energy Technology Data Exchange (ETDEWEB)

Orientational constraints obtained from solid state NMR experiments on anisotropic samples are used here in molecular dynamics (MD) simulations for determining the structure and dynamics of several different membrane-bound molecules. The new MD technique is based on the inclusion of orientation dependent pseudo-forces in the COSMOS-NMR force field. These forces drive molecular rotations and re-orientations in the simulation, such that the motional time-averages of the tensorial NMR properties approach the experimentally measured parameters. The orientational-constraint-driven MD simulations are universally applicable to all NMR interaction tensors, such as chemical shifts, dipolar couplings and quadrupolar interactions. The strategy does not depend on the initial choice of coordinates, and is in principle suitable for any flexible molecule. To test the method on three systems of increasing complexity, we used as constraints ...

Energy Technology Data Exchange (ETDEWEB)

Reliable facility of cyclotron-based real time neutron radiography system has been developed and applied to some industrial components. The equipment for neutron fluoroscopy is based on a sub-compact cyclotron and a LiF/ZnS (Ag) fluorescent screen viewed by a silicon intensifier target TV camera. The real time image is monitored on a CRT, recorded with a standard video recorder and processed by a digital image processor. The effectiveness of our real time neutron radiograph has been demonstrated to be applicable to not only the dynamic observation but also the magnifying and stereoscopic observation of fluoroscopic images.

British Library Electronic Table of Contents (United Kingdom)

This paper provides a physically-based engineering model to estimate radiation hardening of 9%Cr-steels under both displacement damage (dpa) and helium. The model is essentially based on the dispersed barrier hardening theory and the dynamic re-solution of helium under displacement cascades but incorporating a number of assumptions and simplifications [Trinkaus, J. Nucl. Mater. 318 (2003) 234-340]. As a result, the kinetics of the damage accumulation kept fixed, its amplitude is fitted on one experimental condition. The model was rationalized on an experimental database that mainly consists of 9%Cr-steels irradiated in the range of 50-600degreeC up to 50dpa and with a He-content up to 5000appm. The test temperature effect is taken into account through a normalization procedure based on the...

Energy Technology Data Exchange (ETDEWEB)

The vascular status of femoral heads in the post-traumatic period of intracapsular femoral neck fracture (ICFNF) remains uncertain until the patient actually develops avascular necrosis (AVN). Several methods for predicting the viability of femoral head have been reported, that are not effective or widely used because of unreliability, potential complications, and technical difficulties. The present study involved the use of Dynamic MRI (DMRI) in assessing femoral head vascularity to predict AVN. The role of DMRI was studied prospectively in 30 patients with 31 ICFNF. Fractures were divided in to three types (Type A, B, or C) based on the femoral head vascularity shown by dynamic curve patterns on MRI evaluation. Type A was preserved vascularity, Type B was some decrease in vascularity but still viable while Type C was significantly reduced vascularity. These were followed-up for 6 months to 2 years to observe the final ...

Science.gov (United States)

Page 1. Dynamic Virtual LANs for Adaptive Network Security ... Dynamic Virtual LANs for adaptive network security D. Merani, A. Berni, M. Leonard ...

International Nuclear Information System (INIS)

The proposed Sudbury Neutrino Observatory is based on a Cherenkov detector which has a total of 1000 tonne of heavy water and 1800 tonne of light water for its sensitive volume. The detector is optimized for the measurement of extra-terrestrial low energy electron neutrinos and electron antineutrinos spectra as well as the total neutrino flux independent of neutrino flavours. It will delineate the Standard Solar Model and neutrino propagation aspects of the solar neutrino problem, provide detailed information on the dynamics of stellar collapse and measure neutrino masses and oscillation parameters with high sensitivity.

British Library Electronic Table of Contents (United Kingdom)

The mechanism of abrupt increase of the giant magneto impedance (GMI) ratio in the ion irradiated Co-based amorphous ribbon has been investigated. The grazing incident X-ray diffraction and transmission electron microscope were used to characterize the samples before and after ion irradiation. The GMI-ratio considerably increased in the ion irradiated samples and the GMI response showed strong dependence on the driving frequencies. The Barkhausen noise (BN) signals are increased for the Ar ion irradiated sample with dose of 1x10^1^7 ion/cm^2. The results are interpreted in terms of GMI variation associated with domain wall dynamics.

British Library Electronic Table of Contents (United Kingdom)

Introduction Gastrointestinal bleeding is a common life-threatening problem, causing significant mortality, costs and resource allocation. Its management requires a dynamic multidisciplinary approach that directs diagnostic and therapeutic priorities appropriately. Materials and methods Articles published within the past 15 years, related to gastrointestinal bleeding, were reviewed through MEDLINE search, in addition to current guidelines and standards. Results Decisions of ICU admission and blood transfusion must be individualized based on the extent of bleeding, hemodynamic profile and comorbidities of the patient and the risk of rebleeding. A secure airway may be required to optimize oxygenation and to prevent aspiration. Doses of induction agents must be reduced due to the changes in v...

Energy Technology Data Exchange (ETDEWEB)

A new scheme to accurately retain kinetic electron effects in particle-in-cell (PIC) simulations for the case of electrostatic drift waves is presented. The splitting scheme, which is based on exact separation between adiabatic and on adiabatic electron responses, is shown to yield more accurate linear growth rates than the standard df scheme. The linear and nonlinear elliptic problems that arise in the splitting scheme are solved using a multi-grid solver. The multi-grid particle-in-cell approach offers an attractive path, both from the physics and numerical points of view, to simulate kinetic electron dynamics in global toroidal plasmas.

Energy Technology Data Exchange (ETDEWEB)

This study examines the effects of blasting on waste dumps at open pit mining operations. Of specific concern were mining operations at the base of a five hundred foot high waste dump such as the operation at the South Pit of the Smoky-River Coal Ltd. property near Grande Cache, Alberta. An assessment of waste dump stability including factors such as quasi-static deformation behaviour, historical dump deformation behaviours and potential blasting effects was undertaken. It is concluded that safe blasting may be carried out in proximity to waste dumps, but monitoring of dump behaviour is recommended to ensure operational safety. 22 refs., 4 apps.

Energy Technology Data Exchange (ETDEWEB)

The freezing of liquid in the form of a granule on a cooled substrate is considered. On the basis of a hypothesis regarding the form of the isotherms in the granule, an analytical solution of the Stefan problem is obtained for two limiting cases: when a/sub d/ >> a/sub s/ and a/sub d/ << a/sub s/, where a/sub s/ and a/sub d/ are the thermal conductivity of the substrate and drop, respectively. The results of calculating the crystallization times of the granules as a function of their dimensions (height and diameter) and the substrate temperature, and also the dynamics of temperature variation at the base of the granule in the course of crystallization, are in good agreement with the experimental data.

Energy Technology Data Exchange (ETDEWEB)

The outward radial expansion of a free liquid annulus is a common problem of both earlier and current ICF blanket design. Whether the annulus fractures or not depends on the internal pressure and surface stability. In this paper a model based on incompressible cylindrically symmetric flow is used to get a theoretical solution similar to that of the Rayleigh's solution for bubble dynamics. The pressure inside the annulus is found positive all time but the peak is lowering during the expansion. Besides, both surfaces are Taylor stable during such motion. Thus, it is concluded that an annulus in outward radial motion will not cavitate or breakup.

British Library Electronic Table of Contents (United Kingdom)

Abstract Telecare has become an increasingly common medical service in recent years. However, new service must be close to the market and be market-driven to have a high likelihood of success. This article analyzes the business model of a telecardiology service managed by a general hospital. The methodology of the article is as follows: (1) initially it describes the elements of the service based on the ontology of the business model, (2) then it transfers these elements into the choices for business model dynamic loops and examines their validity, and (3) finally provides an empirical financial analysis of the service to assess the profit-making possibilities.

CERN Document Server

Two relativistic approaches are considered to evaluate the quasielastic double-differential and integrated neutrino-nucleus cross sections. One, based on the relativistic impulse approximation, relies on the microscopic description of nuclear dynamics using relativistic mean field theory, and incorporates a description of the final-state interactions. The second is based on the superscaling behavior exhibited by electron scattering data and its applicability, due to the universal character of the scaling function, to the analysis of neutrino scattering reactions. The role played by the vector meson-exchange currents in the two-particle two-hole sector is also incorporated and the results obtained are compared with the recent data for neutrinos measured by the MiniBooNE Collaboration.

Energy Technology Data Exchange (ETDEWEB)

The study abstracted aims at analyzing the economic effects of energy policies using simulations. Emphasis is on assessing the effects of decisions in favour of an expanding electric power industry based on nuclear energy and hard coal. The study discusses alternative assumptions concerning the cost involved, pollution abatement measures, shutdown and dismantling costs etc. Input-output analyses make the simulation model a consistent vehicle. Besides, the model in question is characterized by its explaining the investment demand of the different sectors by referring to the continuous annual development of innovative technologies.

British Library Electronic Table of Contents (United Kingdom)

Abstract: In many biological processes heterogeneity within clonal cell populations is an important issue. One of the most striking examples is a population of cancer cells in which after a common, identical death signal some cells die whereas others survive. The reason for this heterogeneity is intrinsic and extrinsic noise. In this paper we present a mechanistic multi-scale modeling framework for cell populations, in which the dynamics of every individual cell is captured by a parameter dependent stochastic differential equation (SDE). Heterogeneity among individual cells is accounted for by differences in parameter values, modeling extrinsic influences. Based on the statistical properties of the extrinsic noise and the SDE model for the individual cell, a partial differential equation (...

International Nuclear Information System (INIS)

To develop the advanced subchannel analysis code, the dominant factors that influence the boiling transitional process must be taken into account in the mechanistic constitutive equations based on the flow geometries and the fluid properties. The dominant factors that influence the boiling transitional processes are (1) the gas-liquid re-distribution by cross flow, (2) the liquid film dryout, (3) the two-phase flow regime transition, (4) the droplet deposition, and (5) the spacer-droplet interaction. At first, we indicated the strategy for the development of the constitutive equations for the five dominant factors based on the experimental database by the latest measurement technique and the latest computational fluid dynamics method. Then, the problems of the present constitutive equations and the improvement plan of the constitutive equations were indicated. Finally, the layered structure for the two-phase/three-field ...

British Library Electronic Table of Contents (United Kingdom)

This paper describes a comprehensive model of wastewater treatment in secondary facultative ponds, which combines 3D hydrodynamics with a mechanistic water quality model. The hydrodynamics are based on the Navier-Stokes equation for incompressible fluids under shallow water and Boussinesq assumptions capturing the flow dynamics along length, breadth and depth of the pond. The water quality sub model is based on the Activated Sludge Model (ASM) concept, describing COD and nutrient removal as function of bacterial growth following Monod kinetics, except for Escherichia coli removal, which was modelled as first order decay. The model was implemented in the Delft3D software and was used to evaluate the effect of wind and the addition of baffles on the water flow pattern, temperature profiles i...

DEFF Research Database (Denmark)

Udgivelsesdato: 2008

KoreaScience (Korea)

Full Text Available

Science.gov (United States)

This report contains the study on the dynamic characteristics of Wolsung fuel rod and on the dynamic balancing of rotating machinery to evaluate the performance of nuclear reactor components. The study on the dynamic characteristics of Wolsung fuel rod wa...

Energy Technology Data Exchange (ETDEWEB)

Chapter 2 describes the worldwide increase of primary energy consumption, which is expected in coming decades and results in possible solutions of a decentralised energy supply that is mainly based upon renewable energy carriers and the use of cogeneration systems. Chapter 3 shows the characteristics of decentralised system components that have been investigated in the frame of this research work as well as the resulting model library to depict the operational performance of the individual components and their mutual influence. A detailed dynamic simulation of a complete fuel cell system based on a steam reformer including the concept of local and superordinate control circuits is presented in chapter 4. Chapter 5 includes the integrated concepts for the intelligent and adaptable management of complex decentralised energy systems as well as a description of their implementation. Apart from the applied metaheuristic ...

Energy Technology Data Exchange (ETDEWEB)

Polysaccharides like cellulose and chitosan are known for their filmic properties. This paper concerns the synthesis and the study of chitosan-based polymer electrolytes. A preliminary work concerns the study of glucosamine reactivity. The poly-condensation of chitosan ethers (obtained by reaction with ethylene oxide or propylene oxide) with bifunctional and monofunctional oligo-ethers leads to the formation of thin lattices (10 {mu}m) having excellent mechanical properties. The presence of grafted polyether chains along the polysaccharide skeleton allows to modify the vitreous transition temperature and the molecular disorder of the system. Two type of polymer electrolytes have been synthesized: electrolytes carrying a dissolved alkaline metal salt and ionomers. The analysis of their thermal, dynamical mechanical, nuclear magnetic relaxation, electrical, and electrochemical properties shows that this new class of polymer electrolytes has the ...

Energy Technology Data Exchange (ETDEWEB)

A dust extraction system removes the contaminated air at source by means of a hood. The extraction system for dust is essentially a ducted air system that prevents excessive employee exposure to dust in the working zone. The four major mechanisms that remove the contaminants in an extraction system are: - capture of contaminants by hoods - transport of contaminated air in duct network - separation of dust in the collector - exhaust of clean air through stack. The current methods of design are based on empirical relations, multi-variable tables, graphs and nomographs that have been derived from the principle of fluid mechanics and particle dynamics. However, the empirical formulae, tables and graphs are used in different geographical locations of the world having different environmental conditions and geo-characteristics of dust particles. Therefore, it is required to establish a rational design method that will be based on ...

British Library Electronic Table of Contents (United Kingdom)

Objectives: Human influenza A (H1N1) 2009 has caused severe epidemics in many countries, but its dynamics in spatial and temporal contexts have so far been poorly appreciated. Methods: A total of 24,414 laboratory confirmed human influenza A (H1N1) 2009 cases reported from May to September 2009 in Hong Kong were evaluated, using a Geographic Information System (GIS)-based approach. Spatio-temporal clustering was assessed after dividing Hong Kong into 4 geographic sectors, 18 districts and 500 m x 500 m cells. Global Moran's I, Local Moran's I and SaTScan(TM) were used in the exploration. Results: Spatio-temporal clusters first appeared on Hong Kong Island at week 3, alongside multiple foci suggestive of infection nidus introduced from abroad. The clusters grew rapidly and became confluent ...

International Nuclear Information System (INIS)

The current trend towards the increased use of risk assessment in the regulation of nuclear power plants will inevitably result in changes in the analysis of fire protection systems and the methods of analysis. Before fire protection can be regulated on a risk basis, a consensus must be reached on a number of issues. One key issue is what types of computational tools will be allowable for analyzing fire events, and what types of scenarios those tools will be approved for use. Reaching this consensus will require an understanding of the types of computational tools available and their inherent advantages and disadvantages. To aid with this understanding, three different methods of fire simulation are applied to an oil pool fire test in the HDR (Heiss Dampf Reaktor) containment test facility. These methods are a hand calculation, the zone model code CFAST (Consolidated Model of Fire Growth and Smoke Transport), and the computational fluid dynamics code FDS (Fire ...

Energy Technology Data Exchange (ETDEWEB)

The success in developing of the oil industry operating in offshore-onshore terminals, connected by pipelines with the facilities of the coastal zone, can be attributed partially to the beach morpho dynamic monitoring. This study represents a solution to the concerns of the technical operations in coastal zones because it minimizes the impact of the petroleum production and it assures the environmental protection associated to the risks of the pipelines breaking. This impact type results mainly of the vertical and horizontal displacements of the beach, from the coastal dunes to the shore face. The mobility of the profile is associated to the magnitude of the sedimentary processes, which reproduce naturally or not, in scale of time that can vary among few days, years or decades. For the monitoring and interpretation of the beach profile mobility the following methods are recommended: calculation of the closure depth with base in the wave data; ...

CERN Document Server

Bayesian optimization (BO) algorithms try to optimize an unknown function that is expensive to evaluate using minimum number of evaluations/experiments. Most of the proposed algorithms in BO are sequential, where only one experiment is selected at each iteration. This method can be time inefficient when each experiment takes a long time and more than one experiment can be ran concurrently. On the other hand, requesting a fix-sized batch of experiments at each iteration causes performance inefficiency in BO compared to the sequential policies. In this paper, we present an algorithm that asks a batch of experiments at each time step t where the batch size p_t is dynamically determined in each step. Our algorithm is based on the observation that the sequence of experiments selected by the sequential policy can sometimes be almost independent from each other. Our algorithm identifies such scenarios and request those experiments at the same time ...

International Nuclear Information System (INIS)

This paper presents the application of hydraulic network analysis to evaluate the performance of butterfly valves in nuclear power plant applications. Required actuation torque for butterfly valves in high-flow applications is often dictated by peak dynamic torque. The peak dynamic torque, which occurs at some intermediate disc position, requires accurate evaluation of valve flow rate and pressure drop throughout the valve stroke. Valve flow rate and pressure drop are significantly affected by the valve flow characteristics and the hydraulic system characteristics, such as pumping capability, piping resistances, single and parallel flow paths, system hydrostatic pressure, and the location of the motor-operated valve (MOV) within the system. A hydraulic network analysis methodology that addresses the effect of these parameters on the MOV performance is presented. The methodology is based on well-established engineering ...

Energy Technology Data Exchange (ETDEWEB)

A study was conducted to predict indoor ventilation, smoke movement and fire propagation in a new building currently under construction at the Ecole Polytechnique de Montreal. It was conducted in response to concerns regarding the impact that air quality, in normal operation conditions, and smoke concentration, in the event of a fire, may have on occupants of a building. A detailed three-dimensional model of the new building was constructed using the NURBS-based modeler, Rhino. Simulations of fire propagation and airflow ventilation were performed in different areas of the building. The flow pattern data was analyzed using the computational fluid dynamics (CFD) program called FLUENT. It predicted air flow conditions and estimated the mean age of air (MAA) in the room. Real-world geometries, such as diffuser inlets, have a significant impact on overall fluid flow behaviour and are necessary for this type of analysis. The fire simulation was ...

Energy Technology Data Exchange (ETDEWEB)

In addition to ceramics, alloys such as tool steel and nickel- and iron-based superalloys are being considered for high temperature applications such as missile bearings and low heat rejection engines. Studies were made to lubricate a nickel-based superalloy at 500{degrees}C, by using a vaporized aryl phosphate ester, at a concentration of 0.1% in air. From deposition and wear studies it was found that it was impossible to form a good polymeric coating on the superalloy surface. Energy dispersive X-ray analyzer (EDXA) analysis showed that this was due to minute quantities of aluminum in the alloy segregating to the surface, upon being heated to 500{degrees}C, forming a passive oxide coating. It was necessary to activate the surface, in order to lubricate the material successfully. A method of activation by electrodepositing the surface with a layer of iron oxide was developed. Once activated, a good lubricous polymer was formed on the ...

Science.gov (United States)

Most palladium thin film based hydrogen gas sensors have response and recovery times that are too long to make them useful in vehicular and stationary gas leak detection applications. In contrast, a palladium-silver thin film based microcantilever (MC) hydrogen gas microsensor is reported herein with near ideal response characteristics for use in these hydrogen economy related applications. Specifically, 3-10 second response and recovery times have been measured for these sensors in contrast to previous sensor response measurements of several to tens of minutes using Pd thin film and MC based sensing techniques. The much reduced response times observed in the present study are attributed to a wet chemical Pd-Ag thin film deposition technique and a gas conditioning protocol that produces a highly nanostructured, porous film that rapidly adsorbs and desorbs H2, allowing rapid equilibration with the H2 concentration in the ...

Science.gov (United States)

We have developed a transportable container based direct detection Doppler lidar based on the double-edge molecular technique. The pulsed solid state system was built at the University of Geneva. It was used to make range resolved measurements of the atmospheric wind field as part of the VALID campaign at the Observatoire de Haute Provence in Provence, France in July 1999. Comparison of our lidar wind measurements, which were analyzed without knowledge of the results of rawinsonde measurements made under the supervision of ESA, show good agreement with these rawinsondes. These are the first Doppler lidar field measurements made with an eyesafe direct detection molecular-based system at 355 nm and serve as a demonstrator for future spaceborne direct detection wind systems such as the Atmospheric Dynamics mission. Winds are an important contributor to sea surface temperature measurements made with the ...

International Nuclear Information System (INIS)

This paper provides a physically-based engineering model to estimate radiation hardening of 9%Cr-steels under both displacement damage (dpa) and helium. The model is essentially based on the dispersed barrier hardening theory and the dynamic re-solution of helium under displacement cascades but incorporating a number of assumptions and simplifications [Trinkaus, J. Nucl. Mater. 318 (2003) 234-340]. As a result, the kinetics of the damage accumulation kept fixed, its amplitude is fitted on one experimental condition. The model was rationalized on an experimental database that mainly consists of ?9%Cr-steels irradiated in the range of 50-600 deg. C up to 50 dpa and with a He-content up to 5000 appm. The test temperature effect is taken into account through a normalization procedure based on the change of the Young's modulus and the anelastic deformation that occurs at high temperature. Despite the large ...

CERN Document Server

Liquid-liquid wetting failure is investigated in a two-dimensional Couette system with two immiscible fluids of arbitrary viscosity. The problem is solved exactly using a sharp interface treatment of hydrodynamics (lubrication theory) as a function of the capillary number, viscous ratio and separation of scale, i.e. slip length versus macroscopic scale of the system. The existence of critical velocities, above which no stationary solutions are found, is analyzed in detail in terms of the relevant parameters of the system. Comparisons with existing analysis for other geometries are also carried out. A numerical method of analysis is also presented, based on diffuse interface models obtained from multiphase extensions of the lattice Boltzmann equation (LBE). Sharp interface and diffuse interface models are quantitatively compared face to face indicating the correct limit of applicability of the diffuse interface models.

International Nuclear Information System (INIS)

The Container Analysis Fire Environment (CAFE) computer code has been developed to model all relevant fire physics for predicting the thermal response of massive objects engulfed in large fires. It provides realistic fire thermal boundary conditions for use in design of radioactive material packages and in risk-based transportation studies. The CAFE code can be coupled to commercial finite-element codes such as MSC PATRAN/THERMAL and ANSYS. This coupled system of codes can be used to determine the internal thermal response of finite element models of packages to a range of fire environments. This document is a user manual describing how to use the three-dimensional version of CAFE, as well as a description of CAFE input and output parameters. Since this is a user manual, only a brief theoretical description of the equations and physical models is included.

British Library Electronic Table of Contents (United Kingdom)

In this paper, we investigate the relationship between the subprime asset-backed collateralized debt obligations (CDO) market and Large Complex Financial Institutions (LCFIs). We attempt to account for the dynamics between the ABX index returns and the banks' equity returns through conditioning our analysis on the historical correlation between the variables. Three key results emerge from the analysis. First, we find a positive correlation between movements of the ABX index and the equity returns for all the LCFIs. Second, the volatility of ABX index returns tend to be transmitted to the volatilities of the equity returns of the financial institutions. Third, ABX prices changes lead equity returns changes of the European-based LCFIs. For the US LCFIs a two-way linkage emerges.

British Library Electronic Table of Contents (United Kingdom)

SummaryBackground Intracellular transport via processive kinesin, dynein, and myosin molecular motors plays an important role in maintaining cell structure and function. In many cases, cargoes move distances longer than expected for single motors; there is significant evidence that this increased travel is in part due to multiple motors working together to move the cargoes. Although we understand single motors experimentally and theoretically, our understanding of multiple motors working together is less developed. Results We theoretically investigate how multiple kinesin motors function. Our model includes stochastic fluctuations of each motor as it proceeds through its enzymatic cycle. Motors dynamically influence each other and function in the presence of thermal noise and viscosity. We...

International Nuclear Information System (INIS)

We have used polarised neutrons to measure the integrated magnetic cross-section of a dilute alloy of Ce in Y a Kondo system, T_K#approx#40 K. Previous polarised neutron measurements of the field-induced magnetic form factor found no anomalies that could be attributed to the formation of a spin compensation cloud around the Ce ion. The present measurements, focused on the diffuse low-Q range, represent information over a very wide length scale in real space. Again, they show no changes in the Q-dependence of the form-factor at low temperatures that could be attributed to the formation of a spin compensation cloud. An alternative interpretation of the phenomenon based on the dynamical magnetic susceptibility of Y-Ce is proposed.

Energy Technology Data Exchange (ETDEWEB)

In the thermal hydraulics codes developed for fire safety analysis and for containment thermal hydraulic analysis, junctions in the multi-compartment geometries is often modeled as uni-directional junctions. However, ceiling junctions are known to depict unstable/oscillatory bi-directional flow behavior. Detailed investigations have been carried out to understand the unstable flow behaviour of a junction by analyzing an earlier reported experiment and its subsequent two dimensional numerical RANS based study of fire in an enclosure. The authors attempt more realistic and desired three dimensional and inherently transient large eddy simulations using a computer code Fire Dynamics Simulator (FDS). The paper presents the details of the analysis, the results obtained and further studies required to be conducted so that the findings can be applied to the fire/containment thermal hydraulics analysis codes successfully. (orig.)

Energy Technology Data Exchange (ETDEWEB)

This paper describes the design and operating experience with a high performance control system tailored to the requirements of the SuperHILAC accelerator. A large number (20) of the latest 16-bit microcomputer boards are used in a parallel-distributed manner to get a high system bandwidth. Because of the high bandwidth, software costs and complexity are significantly reduced. The system by its very nature and design is easily upgraded and repaired. Dynamically assigned and labeled knobs, together with touch-panels, allow a flexible and efficient operator interface. An X-Y vector graphics system provides for display and labeling of real-time signals as well as general plotting functions. This control system allows attachment of a powerful auxiliary computer for scientific processing with access to accelerator parameters.

International Nuclear Information System (INIS)

The identification of the unknown parameters of the Duffing's mechanical system, based on an algebraic approach, is presented. This approach is fast, accurate, and simple to numerically implement. Also, the method, combined with a suitable invariant filter, can became robust against high frequency output measurement noises. Our method uses the availability of one measurable output and produces an exact formula for the unknown parameters, which may be realized in terms of iterated convolutions. First, we show that the Duffing's system parameters are linearly identifiable with respect to the position variable, then we obtain a linear system where the unknowns are the unavailable parameters. Suitable algebraic operations on the output differential equations makes the identification schema independent of the unavailable initial conditions of the underlying nonlinear dynamical system.

Energy Technology Data Exchange (ETDEWEB)

The physics of density limit phenomena in toroidal helical plasmas based on an analytic point model of toroidal plasmas is discussed. The combined mechanism of the transport and radiation loss of energy is analyzed, and the achievable density is derived. A scaling law of the density limit is discussed. The dependence of the critical density on the heating power, magnetic field, plasma size and safety factor in the case of L-mode energy confinement is explained. The dynamic evolution of the plasma energy and radiation loss is discussed. Assuming a simple model of density evolution, of a sudden loss of density if the temperature becomes lower than critical value, then a limit cycle oscillation is shown to occur. A condition that divides the limit cycle oscillation and the complete radiation collapse is discussed. This model seems to explain the density limit oscillation that has been observed on the W7-AS stellarator. (author)

British Library Electronic Table of Contents (United Kingdom)

Purpose - This paper seeks to deal with the history of Research and Development (R&D) management. It takes the history of the R&D Department of the Royal Philips Electronics of The Netherlands as an example to unravel the dynamics behind industrial R&D management. Design/methodology/approach - This paper is based upon historical and theoretical studies on industrial R&D institutions and research cultures. Findings - The paper proposes that the directors of the Philips R&D Department continually shaped and reshaped the organization in order to retain researchers with creative ideas, and to stimulate innovativeness. The R&D-management was the outcome of a search process that comprehended a mixture of scientific and industrial (management) skills, knowledge and experti...

International Nuclear Information System (INIS)

The objective of this research is to replace the current flow regime dependent interfacial area correlations in the thermal-hydraulic system analysis codes with an interfacial area transport equation, which dynamically models two-phase flow regime transitions. The interfacial area transport equation applicable to bubbly flows has been developed based on mechanistic modeling of bubble interaction. Detailed experiments have been performed for bubbly conditions in 2.54, 5.08 and 10.16-cm ID pipes to benchmark the model. This new approach predicts the continuous changes of the interfacial area and will eliminate artificial bifurcations stemming from the use of the static flow regime transition criteria. This paper presents the preliminary results of incorporating the one-group transport equation into the USNRC consolidated code, currently under development. The framework for the two-group transport equation and the necessary constitutive relations ...

British Library Electronic Table of Contents (United Kingdom)

Various SST indices in the Indo-Pacific region have been proposed in the literature in light of a long-range seasonal forecasting of the Indian Summer Monsoon (ISM). However, the dynamics associated with these different indices have never been compared in detail. To this end, the present work re-examines the variabilities of ISM rainfall, onset and withdrawal dates at interannual timescales and explores their relationships with El Ni?o-Southern Oscillation (ENSO) and various modes of coupled variability in the Indian Ocean. Based on recent findings in the literature, five SST indices are considered here: Ni?o3.4 SST index in December?January both preceding [Nino(?1)] and following the ISM [Nino(0)], South East Indian Ocean (SEIO) SST in February?March, the Indian Ocean Basin (IOB) mode in ...

CERN Document Server

An analysis of the cross section for hadronic production of gluino-squark pairs close to threshold is presented. Within the framework of non-relativistic QCD a significant enhancement compared to fixed order perturbation theory is observed which originates from the characteristic remnants of the gluino-squark resonances below the nominal pair threshold. The analysis includes all colour configurations of S-wave gluino-squark pairs, i.e. triplet, sextet and 15 representation. Matching coefficients at leading order are separately evaluated for all colour configurations. The dominant QCD corrections, arising from initial- and final-state radiation are included. The non-relativistic dynamics of the gluino pair is solved by calculating the Green's function in Next-to-Leading Order (NLO). The results are applied to benchmark scenarios, based on Snowmass Points and Slopes (SPS). As a consequence of the large decay rate of at least one of the ...

British Library Electronic Table of Contents (United Kingdom)

Fault symptoms of running gearboxes must be detected as early as possible to avoid serious accidents. Diverse advanced methods are developed for this challenging task. However, for multiwavelet transforms, the fixed basis functions independent of the input dynamic response signals will possibly reduce the accuracy of fault diagnosis. Meanwhile, for multiwavelet denoising technique, the universal threshold denoising tends to overkill important but weak features in gear fault diagnosis. To overcome the shortcoming, a novel method incorporating customized (i.e., signal-based) multiwavelet lifting schemes with sliding window denoising is proposed in this paper. On the basis of Hermite spline interpolation, various vector prediction and update operators with the desirable properties of biorthog...

British Library Electronic Table of Contents (United Kingdom)

Using the Galaxy as an example, we study the effect of Formula Not Shown force on the rotational curves of gas and plasma in galaxies. Acceptable model for the galactic magnetic field and plausible physical parameters are used to fit the flat rotational curve for gas and plasma based on the observed baryonic (visible) matter distribution and Formula Not Shown force term in the static MHD equation of motion. We also study the effects of varied strength of the magnetic field, its pitch angle and length scale on the rotational curves. We show that Formula Not Shown force does not play an important role on the plasma dynamics in the intermediate range of distances 6?12?kpc from the centre, whilst the effect is sizable for larger r (r?15?kpc), where it is the most crucial.

CERN Document Server

We review various field theory approaches to the description of neutrino oscillations in vacuum and external fields. First we discuss a relativistic quantum mechanics based approach which involves the temporal evolution of massive neutrinos. To describe the dynamics of the neutrinos system we use exact solutions of wave equations in presence of an external field. It allows one to exactly take into account both the characteristics of neutrinos and the properties of an external field. In particular, we examine flavor oscillations an vacuum and in background matter as well as spin flavor oscillations in matter under the influence of an external electromagnetic field. Moreover we consider the situation of hypothetical nonstandard neutrino interactions with background fermions. In the case of ultrarelativistic particles we reproduce an effective Hamiltonian which is used in the standard quantum mechanical approach for the description of neutrino ...

DEFF Research Database (Denmark)

The determination of conformational preferences in unfolded and disordered proteins is an important challenge in structural biology. We here describe an algorithm to optimize energy functions for the simulation of unfolded proteins. The procedure is based on the maximum likelihood principle and employs a fast and efficient gradient descent method to find the set of parameters of the energy function that best explain the experimental data. We first validate the method by using synthetic reference data, and subsequently apply the algorithms to data from nuclear magnetic resonance spin-labeling experiments on the Delta 131 Delta fragment of Staphylococcal nuclease. A significant strength of the procedure that we present is that it directly uses experimental data to optimize the energy parameters, without relying on the availability of high resolution structures. The procedure is fully general and can be applied to a range of experimental data and energy functions ...

British Library Electronic Table of Contents (United Kingdom)

Abstract Dynamic testing of a phosphoric acid-based high temperature PEM fuel cell shows a peculiar phenomenon. A certain current loss is observed after temperature cycling at constant voltage. This loss is incidentally recovered by applying a cell voltage spike to open circuit voltage. Experimental investigations into temperature, cell voltage, and ageing effects show that this phenomenon might occur due to the orientation of the adsorbed phosphate species on the platinum catalyst surface. Along with some supporting literature and experimental results, a hypothesis is presented in order to explain this occurrence. Phosphoric acid adsorption hysteresis on platinum catalyst due to temperature cycling could cause the temporary cell current loss. Electrode potential-dependent molecule symmetr...

CERN Document Server

The LHCb experiment has chosen to use the SAM framework (Service Availability Monitoring Environment from EGEE-II) [1] make extensive tests of the LHCb environment at all the accessible grid resources. The availability and the proper definition of the local Computing and Storage Elements, user interfaces as well as the WLCG software environment are checked. The SAM framework is also used to pre-install the LHCb applications in the shared software area provided by each site. The deployment of the LHCb applications is based on a python tool developed inside the experiment. It is used for software management including incremental installation of interdependent packages and clean package removal. After the application software is installed a validation test of the whole MC chain is run. According to the results of the experiment specific SAM tests, the sites are (re)integrated into the LHCb production system managed by DIRAC [2]. The possibility of automated ...

British Library Electronic Table of Contents (United Kingdom)

Effective and efficient strategic decision making is the backbone for the success of a business organization. These decision making processes, used among its competitors in a particular industry, determine whether the business will continue to survive or not. In this research, fuzzy logic (FL) concept and game theory are being used to model strategic decision making processes by business organizations. Competition between business organizations is viewed as a game with each business organization as a player. A player formulates his own decisions by making his strategic moves based on uncertain information. This is the information he has about the opponents with respect to prevailing or anticipated market demand, cost of production, marketing, consolidation efforts and some other business v...

Energy Technology Data Exchange (ETDEWEB)

Thermophotovoltaic energy conversion achieves direct conversion of thermal energy to electricity without the need for complex dynamic machinery operating in one of several possible thermodynamic cycles. This paper presents an analysis of a hybrid solar thermophotovoltaic (STPV) energy conversion system in which a receiver/photovoltaic (PV) array subsystem is powered by either a solar concentrator or a fossil fuel combustion source. The overall TPV system efficiency is calculated using an appropriate selective emitter and a spectrally tuned solar cell designed to achieve maximum conversion efficiency in the narrow band emitted by the selective emitter. Two limiting cases are examined to place upper and lower bounds on system performance. The estimates of system performance are based on actual experimental data from PV cells and selective emitters.

Energy Technology Data Exchange (ETDEWEB)

Problems can sometimes occur during the construction of cast in-situ concrete piles. These foundations are formed by drilling a substantial hole into the ground and subsequently filling it with steel reinforcement and wet concrete. Several well-documented cases exist where concrete has not filled the hole and substantial voids have been left in the apparently completed pile. A theory has been developed by which it is possible to identify the nature, size and position of a finite defect within a suspect pile. The technique is based on the concept of receptances, and requires information obtained from vibration tests performed on piles after the concrete has hardened, and the nominal dimensions and material properties of the pile. The application of the theory is demonstrated using data relating to a pile with a known defect. The theory described in this paper ignores the effect of the surrounding soil; this can be included by further development of the theory.

Energy Technology Data Exchange (ETDEWEB)

When the transmission line is very long or the generator is operated at a power factor nearly equal to 1.0, the machine regulated by an automatic voltage regulator (AVR) cannot be operated stably due to poor dynamic stability. To overcome this difficulty, the so called power system stabilizer (PSS) is very useful, in that output power or rotor speed of the generator is used as a feedback signal. The primary obective of the PSS is to damp the swing of the generator as quickly as possible. A method is proposed for designing PSS which yields a given eigenvalue. In the second method, the use of a Heffron-Phillips model is discussed. Next, a detailed procedure for the proposed design method is presented. A generalized method of a PSS design based on Park's equation and matrix operation is proposed.

Science.gov (United States)

A six-axis active vibration isolation system (AVIS) is designed by using the direct driven guide and ball contact mechanisms in order to have no cross-coupling between actuators. The point contact configuration gives an advantage of having an easy assembly of eight voice coil actuators to an upper and a base plate. A voice coil actuator is used since it can provide a large displacement and sufficient bandwidth required for vibration control. The AVIS is controlled considering the effect of flexible vibration mode in the upper plate and velocity sensor dynamics. A loop shaping technique and phase margin condition are applied to design a vibration controller. The performances of the AVIS are investigated in the frequency domain and finally validated by comparing with the passive isolation system. The scanning profiles of the specimen are compared together by using the atomic force microscope. The robustness of the AVIS is verified by showing the ...

CERN Document Server

In order to understand the parameters of the standard model of electroweak and strong interactions (coupling constants, masses, mixing angles) one needs to embed the standard model into some larger theory that accounts for the observed values. This means some additional sector is needed that fixes and stabilizes the values of the fundamental constants of nature. In these lecture notes we describe in nontechnical terms how such a sector can be constructed. Our additional sector is based on rapidly fluctuating scalar fields that, although completely deterministic, evolve in the strongest possible chaotic way and exhibit complex behaviour. These chaotic fields generate potentials for moduli fields, which ultimately fix the fundamental parameters. The chaotic dynamics can be physically interpreted in terms of vacuum fluctuations. These vacuum fluctuations are different from those of QED or QCD but coupled with the same moduli fields as QED and QCD ...

Environmental Research Database

Objectives1. To create a strong, interdisciplinary evidence base about the relationships linking ecosystems, agrobiodiversity, wild biodiversity, and sustainable livelihoods, including the use of trade-off analysis (modeling the relationships between agricultural productivity, levels of biodiversity, and ecosystem resilience); crop evolutionary studies (wild relative/crop interactions) and socioeconomic, cultural, and nutritional studies of the contribution of biodiversity to different livelihoods asset [continued...]DescriptionAgriculture, ecosystems, and humans have co-evolved over millennia in the Andean-Amazonian region, creating the richest of all Vavilov centers of crop origin and diversity. The conservation of a wide range of domesticated crops and landraces (i.e., indigenous, ancestral varieties or cultivars that are distinct, uniform, and stable) and their co-evolution with crop wild relatives (CRW) has been essential for food security, adaptation to ...

CERN Document Server

A possibility of geophysical measurements using the large scale laser interferometrical gravitational wave antenna is discussed. An interferometer with suspended mirrors can be used as a gradiometer measuring variations of an angle between gravity force vectors acting on the spatially separated suspensions. We analyze restrictions imposed by the atmospheric noises on feasibility of such measurements. Two models of the atmosphere are invoked: a quiet atmosphere with a hydrostatic coupling of pressure and density and a dynamic model of moving region of the density anomaly (cyclone). Both models lead to similar conclusions up to numerical factors. Besides the hydrostatic approximation, we use a model of turbulent atmosphere with the pressure fluctuation spectrum f^{-7/3} to explore the Newtonian noise in a higher frequency domain (up to 10 Hz) predicting the gravitational noise background for modern gravitational wave detectors. Our estimates show that this could pose ...

British Library Electronic Table of Contents (United Kingdom)

This paper investigates the relationship between environmental pollution and economic growth in China based on the environmental Kuznets curve hypothesis, using Chinese provincial data over 1985?2005. Waste gas, waste water and solid wastes are used as environmental indicators and GDP is used as the economic indicator. It is found by panel cointegration test that there is a long-run cointegrating relationship between the per capita emission of three pollutants and the per capita GDP. According to comparisons with the dynamic OLS estimator and the Within OLS estimator, we find that panel cointegration estimation is preferable for all pollutants except for solid wastes. The results also show that all three pollutants are inverse U-shaped, and water pollution has been improved earlier than ga...

Science.gov (United States)

Ab initio lattice dynamics based on linear response method are performed for high pressure phase of yttrium to describe electron-phonon coupling and subsequent superconducting behavior. The critical temperature Tc in fcc-Y increases monotonically with pressure up to 9.25 K at 31 GPa, which is quantitatively in excellent agreement with two quasihydrostatic experiments and is qualitatively compatible with recent experiments. The excellent agreement with experiments gives us a better understanding of the effective pseudopotential ?* as well as spectral function ?2(?)F(?) in yttrium. These results demonstrate that there exists strong electron-phonon coupling in Y within the studied pressure regime, and for lower pressure electron correlation becomes stronger. Generally, it is found that superconductivity in yttrium under pressure can be described quantitatively within standard theory of phonon-mediated superconductivity.

International Nuclear Information System (INIS)

The optically stimulated luminescent (OSL) radiation dosimeter technically surveys a wide dynamic measurement range and a high sensitivity. Optical fiber dosimeters provide capability for remote monitoring of the radiation in the locations which are difficult-to-access and hazardous. In addition, optical fiber dosimeters are immune to electrical and radio-frequency interference. In this paper, a novel remote optical fiber radiation dosimeter is described. The optical fiber dosimeter takes advantage of the charge trapping materials CaS:Ce, Sm that exhibit OSL. The measuring range of the dosimeter is from 0.1 to 100 Gy. The equipment is relatively simple and small in size, and has low power consumption. This device is suitable for measuring the space radiation dose and also can be used in high radiation dose condition and other dangerous radiation occasions. (authors)

Energy Technology Data Exchange (ETDEWEB)

This paper reports on a study to validate the Graphical Network Representation (GRPHREP) model which is being conducted on the Los Alamos National Laboratory Integrated Computer Network (ICN). The GRPHREP model is a software system application based on graph theory and object-oriented programming methodologies. It codified the Department of Energy (DOE) Order 5637.1, which is concerned with classified computer secret policy, restrictions, and requirements. The Los Alamos ICN is required to control access to and support large-scale scientific and administrative computing. Thus, large-scale scientific and administrative computing. Thus we felt that this large, complex, and dynamic network would provide a good test for the graphical and functional capabilities of the model. Furthermore, the ICN is composed of multiple partitions that reflect the sensitivity and classification of the computation (data) and designate the required clearance level for ...

Energy Technology Data Exchange (ETDEWEB)

The resident bald eagles of the lower Columbia River have lower productivity and higher contaminant levels than other bald eagles of the Pacific Northwest. The primary population stressors are believed to be habitat loss, human disturbance, p,p{prime}DDE, PCBs, dioxins and furans. The primary effect of habitat loss is to reduce the carrying capacity of the region for nesting sites, and the primary effects of human disturbance and contamination by organic compounds are to reduce productivity. The purpose of this study was to quantitatively evaluate the effects of all of, these potential stressors on the bald eagle population dynamics. A model of the population dynamics was developed. The model structure includes a physiologically-based toxicokinetic (PBTK) submodel to estimate the degree of contamination, which is linked via a toxicology submodel to a population dynamics submodel. The PBTK submodel is ...

Energy Technology Data Exchange (ETDEWEB)

The boundary-integral equation method is well suited for the calculation of the dynamic-stiffness matrix of foundations embedded in a layered visco-elastic halfspace (or a transmitting boundary of arbitrary shape), which represents an unbounded domain. It also allows pile groups to be analyzed, taking pile-soil-pile interaction into account. The discretization of this boundary-element method is restricted to the structure-soil interface. All trial functions satisfy exactly the field equations and the radiation condition at infinity. In the indirect boundary-element method distributed source loads of initially unknown intensities act on a source line located in the excavated part of the soil and are determined such that the prescribed boundary conditions on the structure-soil interface are satisfied in an average sense. In the two-dimensional case the variables are expanded in a Fourier integral in the wave number domain, while in three dimensions, Fourier series in ...

Energy Technology Data Exchange (ETDEWEB)

In robotics inverse dynamics is a standard control concept for highly nonlinear multibody systems. It is shown, however, that inverse dynamics results in a high energy demand. Therefore, linear energy efficient state feedback controllers are designed in a way that a performance index representing the energy consumption is minimized. At the same time inequality constraints such as control error and limited input variables have to be met. For the control design an analytical solution by pole placement is presented as well as a numerical controller optimization. This control design includes small motions in the neighborhood of the operating point. Then, linear controllers are tested with respect to control error and energy consumption when undergoing large displacement motion. It is shown that linear state feedback can only save energy if large control errors are accepted. Therefore, nonlinear systems are optimized as a whole by implementation of ...

Energy Technology Data Exchange (ETDEWEB)

A study of the electron beam dynamics in the linac is conducted for the FERMI free electron laser (FEL) founded for construction at the Sincrotrone Trieste.

International Nuclear Information System (INIS)

English 2009 p. 161-162 Brazil Paula, Viviane Silva de Almeida, Fabio

UK PubMed Central (United Kingdom)

Background and AimsIt is well known that genome size differs among species. However, information on the variation and dynamics of genome size in wild populations and on the early...Full Text Available

UK PubMed Central (United Kingdom)

AIM: To investigate the effects of gallbladder stones on motor functions of the gallbladder and the dynamics of bile flow in asymptomatic gallstone disease.METHODS: Quantitative hepatobiliary...Full Text Available

Science.gov (United States)

... 23 Milstar 25 A Notional Battlespace For Dynamic Wireless Network Simulation/Testing ... Figure 16: GPS Satellite 23 Figure 17: Milstar Satellite 25 ...

International Nuclear Information System (INIS)

We introduce a novel search technique that can identify trans-Neptunian objects in three to five exposures of a pointing within a single Hubble Space Telescope (HST) orbit. The process is fast enough to allow the discovery of candidates soon after the data are available. This allows sufficient time to schedule follow-up observations with HST within a month. We report the discovery of 14 slow-moving objects found within 50 of the ecliptic in archival data taken with the Wide Field Channel of the Advanced Camera for Surveys. The luminosity function of these objects is consistent with previous ground-based and space-based results. We show evidence that the size distribution of both high and low inclination populations is similar for objects smaller than 100 km, as expected from collisional evolution models, while their size distribution differs for brighter objects. We suggest that the two populations formed in different parts of the ...

CERN Document Server

Because of the stochastic nature of traffic requirement matrix, it is very difficult to get the optimal traffic distribution to minimize the delay even with adaptive routing protocol in a fixed connection network where capacity already defined for each link. Hence there is a requirement to define such a method, which could generate the optimal solution very quickly and efficiently. This paper presenting a new concept to provide the adaptive optimal traffic distribution for dynamic condition of traffic matrix using nature based intelligence methods. With the defined load and fixed capacity of links, average delay for packet has minimized with various variations of evolutionary programming and particle swarm optimization. Comparative study has given over their performance in terms of converging speed. Universal approximation capability, the key feature of feed forward neural network has applied to predict the flow distribution on each link to ...

International Nuclear Information System (INIS)

The B test series from the course of ISP Nr. 43 was analysed. The boundary conditions measured include the initial temperature of the primary system, the front/slug injection flowrate and temperature, and the pressure drop across the core. Temperature data were collected at 185 thermocouple positions in the downcomer and 38 positions in the lower plenum. The frequency of data acquisition for code predictions was set to 2 Hz, which corresponds to the acquisition frequency of the two experimental setups. Calculations were performed using the FLUENT Computational Fluid Dynamics (CFD) code. This program is based on the finite volume method, The computational mesh was generated by the pre-processor - GAMBIT program. FLUENT uses a control-volume-based technique to convert the governing equations to algebraic equations, which can be solved numerically. This control volume technique consists of integrating the governing equations ...

CERN Document Server

Recent studies have revealed a number of striking dependence patterns in high frequency stock price dynamics characterizing probabilistic interrelation between two consequent price increments x (push) and y (response) as described by the bivariate probability distribution P(x,y) [1,2,3,4]. There are two properties, the market mill asymmetries of P(x,y) and predictability due to nonzero z-shaped mean conditional response, that are of special importance. Main goal of the present paper is to put together a model reproducing both the z-shaped mean conditional response and the market mill asymmetry of P(x,y) with respect to the axis y=0. We develop a probabilistic model based on a multi-component ansatz for conditional distribution P(y|x) with push-dependent weights and means describing both properties. A relationship between the market mill asymmetry and predictability is discussed. A possible connection of the model to ...

International Nuclear Information System (INIS)

Small economies such as New Zealand risk significant economic hardship without careful evaluation of alternatives to petroleum-based transportation due to the adverse effects of climate change and depleting international oil reserves. This paper uses an integrated multi-regional multi-fleet system dynamics model of New Zealand's energy economy to assess the primary impacts of alternative vehicle fleet technologies. Results suggest that hydrogen fuelled HICEs and FCVs may offer significantly greater economic savings than BEVs due to a much lower capital cost. Under our Base Case, 65% of the light fleet are HICEs and FCVs and 5% BEVs. Excluding hydrogen vehicles from the vehicle fleet can result in an average annual cost of US$562 per vehicle between 2015 and 2050. Co-production of hydrogen and electricity using coal gasification with carbon capture and storage is the dominant long term hydrogen production technology. ...

International Nuclear Information System (INIS)

A personal computer based single specimen unloading technique has been demonstrated using a nuclear grade pressure vessel material, A533B Class I steel, and an #alpha#-#beta# titanium alloy, CORONA-5. Experimental parameters investigated in the case of steel include the effect of test temperature, loading rate and neutron irradiation. Results revealed the effect of dynamic strain aging (DSA) as a drop in the critical crack initiation fracture toughness (Jsub(q)); the minimum in Jsub(q) shifts to higher temperatures at higher test speeds as predicted from DSA models. In CORONA-5, the effects of microstructure and heat treatment for two different sizes of equiaxed #alpha# morphology in a #beta#-matrix heat treated to different yield strengths were investigated. It is found that the observed higher values of Jsub(q) and tearing modulus result from a greater tortuosity of the crack path and ease of crack blunting. The largest increase in Jsub(q) ...

Energy Technology Data Exchange (ETDEWEB)

An important aspect of water quality modeling is forecasting water quality variables for real-time management and control applications to enhance, maintain and sustain desirable water qualities. The major objective of this research is to develop daily time series models for forecasting river dissolved-oxygen (DO). The modeling approach adopted herein combines deterministic and stochastic concepts for determining properties of the DO process based on time series data and dynamic mechanisms governing the said process. This is accomplished by deriving a general DO stochastic model structure based on a modified Streeter-Phelps DO-BOD dynamic model. Then some types of nonlinear models namely, self-exciting threshold autoregressive-moving average (SETARMA), amplitude-dependent autoregressive (ADAR) and bilinear (BL) models, and the class of linear autoregressive-moving average (ARMA) models are adopted for ...

Science.gov (United States)

The jet in cross flow (JICF) is a basic flowfield which is relevant to a wide variety of applications which are described to provide context for JICF investigations. Material consistent with the scope of topics presented at the 72nd AGARD Fluid Dynamics Panel Meeting and Symposium on Computational and Experimental Assessment of Jets in Cross Flow on 19-22 April 1993 in Winchester, U.K. is summarized. The JICF research was divided into three time periods: (1) early research - up to 1970, (2) research during the 1970's, and (3) research since 1980. The following areas of experimental activity are discussed; the definition of an effective correlation parameter; the jet flowfield including the jet trajectories, cross-section shape, and jet induced pressures; the effects of jet deflection angle, nozzle shape, pressure ratio, velocity decay, and temperature; and the effect of confined flowfield, ground effects, multiple jets, and adjacent surface geometry. In addition, ...

Science.gov (United States)

S.M. Goltz; NASA Goddard Space Flight Center, Forest Ecosystem Dynamics Project ...

KoreaScience (Korea)

Full Text Available

International Nuclear Information System (INIS)

... Netherlands Kormendy, J. Dominion Astrophysical Observatory, Victoria, British

KoreaScience (Korea)

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Energy Technology Data Exchange (ETDEWEB)

No abstract prepared

Norwegian Open Research Archives (NORA)

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Indian Institute of Science Theses & Dissertations (India)

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KoreaScience (Korea)

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KoreaScience (Korea)

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Science.gov (United States)

Three aspects of the physical geographic environment of the Amazon Basin are considered: (1)

KoreaScience (Korea)

Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Fully coupled, Newton-Krylov algorithms are investigated for solving strongly coupled, nonlinear systems of partial differential equations arising in the field of computational fluid dynamics. Primitive variable forms of the steady incompressible and compressible Navier-Stokes and energy equations that describe the flow of a laminar Newtonian fluid in two-dimensions are specifically considered. Numerical solutions are obtained by first integrating over discrete finite volumes that compose the computational mesh. The resulting system of nonlinear algebraic equations are linearized using Newton`s method. Preconditioned Krylov subspace based iterative algorithms then solve these linear systems on each Newton iteration. Selected Krylov algorithms include the Arnoldi-based Generalized Minimal RESidual (GMRES) algorithm, and the Lanczos-based Conjugate Gradients Squared (CGS), Bi-CGSTAB, and Transpose-Free ...

International Nuclear Information System (INIS)

This paper is concerned with the determination of a unique scaling parameter in complex scaling analysis and with accurate calculation of dynamics resonances. In the preceding paper we have presented a theoretical analysis and provided a formalism for dynamical resonance calculations. In this paper we present accurate numerical results for two non-trivial dynamical processes, namely, models of diatomic molecular predissociation and of barrier potential scattering for resonances. The results presented in this paper confirm our theoretical analysis, remove a theoretical ambiguity on determination of the complex scaling parameter, and provide an improved understanding for dynamical resonance calculations in rigged Hilbert space.

International Nuclear Information System (INIS)

The goal of this work is to present a systematic Monte Carlo validation study on the clinical implementation of the enhanced dynamic wedges (EDWs) into the Pinnacle"3 (Philips Medical Systems, Fitchburg, WI) treatment planning system (TPS) and QA procedures for patient plan verification treated with EDWs. Modeling of EDW beams in the Pinnacle"3 TPS, which employs a collapsed-cone convolution superposition (CCCS) dose model, was based on a combination of measured open-beam data and the 'Golden Segmented Treatment Table' (GSTT) provided by Varian for each photon beam energy. To validate EDW models, dose profiles of 6 and 10 MV photon beams from a Clinac 2100 C/D were measured in virtual water at depths from near-surface to 30 cm for a wide range of field sizes and wedge angles using the Profiler 2 (Sun Nuclear Corporation, Melbourne, FL) diode array system. The EDW output factors (EDWOFs) for square fields from 4 to 20 cm wide were measured in ...

Energy Technology Data Exchange (ETDEWEB)

Hybrid models for solving unit commitment problem have been proposed in this paper. To incorporate the changes due to the addition of new constraints automatically, an expert system (ES) has been proposed. The ES combines both schedules of units to be committed based on any classical or traditional algorithms and the knowledge of experienced power system operators. A solution database, i.e. information contained in the previous schedule is used to facilitate the current solution process. The proposed ES receives the input, i.e. the unit commitment solutions from a fuzzy-neural network. The unit commitment solutions from the artificial neural network cannot offer good performance if the load patterns are dissimilar to those of the trained data. Hence, the load demands, i.e. the input to the fuzzy-neural network is considered as fuzzy variables. To take into account the uncertainty in load demands, a fuzzy decision making approach has also been developed to solve the ...

International Nuclear Information System (INIS)

1 - Description of program or function: T-HEMP3D (Transportable HEMP3D) is a derivative of the STEALTH three-dimensional thermodynamics code developed by Science Applications, Inc. Changes were made primarily in three areas: material specification, coordinate generation, and the addition of sliding surface boundary conditions. STEALTH itself is based entirely on the HEMP3D code written at LLNL. HEMP3D solves problems in solid mechanics involving dynamic plasticity and time-dependent material behavior and problems in gas dynamics. 2 - Method of solution: The equations of motion, conservation equations, and constitutive relations for stresses, strains, hydrostatic pressure, the von Mises yield condition, and artificial viscosity are solved by finite difference methods following the format of the HEMP code (NESC Abstract 775). The physical object is divided into zones defined by 8 grid points. The grid (i,j,k) moves with the ...

Energy Technology Data Exchange (ETDEWEB)

Safety-technical factors related to spontaneous ignition and dust explosions of biomasses were investigated. Parametres of dust explosions and effect of inertisation on the maximum pressure (pmax) and the maximum rate of pressure rise (Kstmax) were studied at elevated initial pressure (1-9 bar). The level of inertisation required to prevent dust explosions totally was determined at different initial pressures. The sensitivity of fuels to spontaneous ignition and the effect of pressure on the sensitivity to and temperature of spontaneous ignition were studied on a pressurised dynamic self-ignition equipment. The effect of inertisation on the self-ignition temperature and alternatives of preventing spontaneous ignition by effective inertisation in the pressure ranges of 1 and 25 bar were investigated. As an example of application, results obtained with the laboratory test equipment were extrapolated to bin sizes used in practice. As a factor contributing to ...

International Nuclear Information System (INIS)

The optical, electromagnetic and mechanical properties of thin films (TFs) are directly correlated to their morphology at the nanoscale. This, in concert with the fact that new deposition techniques are enabling the growth of thin films with very complex morphologies, there is an increasing interest in model-based simulation (MBS) for the design of engineering structures (including nanostructures), and increasing computer speeds are beginning to make MBS an effective design tool capable of bridging the nanoscale with the continuum scale, has made it increasingly important to understand how the nanostructure of a thin film impacts its properties at all length scales. The authors have developed the capability to determine the mechanical properties of thin films with amorphous nanostructure by combining molecular dynamics, i.e., position of particles (e.g., atoms or molecules) and their interatomic potential(s), with continuum mechanics ...

International Nuclear Information System (INIS)

We investigate a two-orbital Anderson lattice model with Ising orbital intersite exchange interactions on the basis of a dynamical mean field theory combined with the static mean field approximation of intersite orbital interactions. Focusing on Ce-based heavy-fermion compounds, we examine the orbital crossover between two orbital states, when the total f-electron number per site n_f is #approx#1. We show that a 'meta-orbital' transition, at which the occupancy of two orbitals changes steeply, occurs when the hybridization between the ground-state f-electron orbital and conduction electrons is smaller than that between the excited f-electron orbital and conduction electrons at low pressures. Near the meta-orbital critical end point, orbital fluctuations are enhanced and couple with charge fluctuations. A critical theory of meta-orbital fluctuations is also developed by applying the self-consistent renormalization theory of itinerant electron ...

Energy Technology Data Exchange (ETDEWEB)

Growth dynamics and biomass production in short-rotation poplar plantations were evaluated at Hanyuan Forestry Farm, Baoying County, P.R.C. Experimental treatments applied in a split-plot design included: four planting densities (1111, 833, 625 and 500 stems ha{sup -1}); three poplar clones (NL-80351, I-69 and I-72) and three rotation lengths. Survival of all three clones was excellent at the experimental site under the imposed management regime. Differences in DBH, height, LAI and above-ground biomass production, however, were manifested among the treatments. Overall the clonal ranking was in the order NL-80351 {>=}I-69 > I-72 by age 6. LAI values ranged from 0.6 to 4.4 m{sup 2} m{sup -2} and differences among four planting densities and three clones were significant throughout the first six years. Above-ground biomass productivity was affected considerably by planting density, clone and rotation length. Within the four densities, the highest biomass ...

Energy Technology Data Exchange (ETDEWEB)

Selected case studies of auroral structure/activity observed at different local times on the dayside are presented and discussed in the context of electrodynamic coupling between the different magnetospheric boundary regions and the ionosphere. The first case addresses the question of the auroral signatures of the two boundary regions referred to as cusp and cleft/LLBL. Combined ground-based and satellite data reveal the different latitudinal zones of auroral forms/particle precipitation/field-aligned current and the relationship with the respective magnetospheric plasma populations, i.e. CPS, BPS, LLBL, and the plasma mantle. Midday auroral breakup events and the related ionospheric ion drift and magnetic observations show many of the features that have been predicted to be ionospheric signatures of flux transfer events. An alternative explanation that has been proposed by others, i.e. ionospheric effect of magnetopause perturbations excited by ...

International Nuclear Information System (INIS)

Dynamic recrystallization (DRX) is the main softening mechanism of magnesium alloy AZ31B in hot deformation. Theoretically, in the flow rule the atomic diffusibility and the driving force of dislocation migration are dependent on the temperature, and the dislocation density and the cumulation of grain boundary energy are dependent on the strain rate. The peak stress will appear when the flow driving force and resistance force reach a balance, after which the stress descending will take place due to recrystallization fraction. Since the DRX is a thermally activated process, the recrystallized volume fraction can be regarded as the function of strain through Avrami equation. Based on this idea, the paper proposes a new constitutive model characterizing dynamic recrystallization for magnesium alloy AZ31B. The model is described by a peak stress and a strain softening rate, in which the peak stress depends only on ...

International Nuclear Information System (INIS)

Non-destructive testing (NDT) is a dynamic technology and progresses with time. Since the issuance of IAEA-TECDOC-628 in 1991, the technology has experienced numerous changes. Advancements in knowledge about the behaviour of materials have led to changes in the applicable NDT codes, standards and specifications. In addition, over the last ten years, as a result of extensive research and development activities worldwide, new NDT techniques and equipment have been developed which are accepted by engineering community. To accommodate the latest developments, modifications are required to training materials. The present publication is an updated version of IAEA-TECDOC-628. The modifications were made during an Advisory Group Meeting, held in Vienna from 25-29 June 2001. The content of the first edition of IAEA-TECDOC-628 has been revised based on the experience of the experts, as well as comments of the end-user industries. The time allotment for ...

Energy Technology Data Exchange (ETDEWEB)

Software has been developed for the calculation of the thermodynamic cycle and the entropy changes in a turbocharged, direct injection, diesel engine based upon the measured cylinder pressure and a shaft encoder output. Assumptions of homogeneous mixture and equilibrium thermodynamic properties are made for the products of combustion and temporal variation in the fluid thermodynamic state is followed in a quasi-steady manner through a series of adjacent equilibrium states, each separated by finite intervals of one degree crank angle (1degCA). The thermodynamic properties are calculated by either of two equivalent formulations -- equilibrium constant or minimisation of Gibbs free energy, and are expressed in algebraic equations of the partial derivative of internal energy and gas constant with respect to temperature, pressure and equivalence ratio. The effect of the engine operating conditions on the thermodynamic cycle is studied, Results show that the ...

Energy Technology Data Exchange (ETDEWEB)

The ALICE heavy-ion particle physics experiment is currently being built at CERN near Geneva. It will use a PC cluster of 900 dual-processor machines for the last stages of the data readout process and a network of 400 microcomputers for the configuration and control of the cluster nodes. One of the most important objectives to be achieved in such experiments is to guarantee the utilized devices are running correctly during the experiment life-time. A second aspect is the extremely high availability and reliability requirements of the applications being run, the so called high level trigger (HLT). The SysMES framework is a scalable, decentralized, fault tolerant, dynamic, rule based tool set for the monitoring of networks of target systems and applications. The management algorithms consist of the following steps: system and application monitoring, recognition of undesirable states, event (message) generation, local event handling on the ...

CERN Document Server

Testing deviation of GR is one of the main goals of the proposed {\\emph{Laser Interferometer Space Antenna}}, a space-based gravitational-wave observatory. For the first time, we consistently compute the generation of gravitational waves from extreme-mass ratio inspirals (stellar compact objects into supermassive black holes) in a well-motivated alternative theory of gravity, that to date remains weakly constrained by double binary pulsar observations. The theory we concentrate on is Chern-Simons (CS) modified gravity, a 4-D, effective theory that is motivated both from string theory and loop-quantum gravity, and which enhances the Einstein-Hilbert action through the addition of a dynamical scalar field and the parity-violating Pontryagin density. We show that although point particles continue to follow geodesics in the modified theory, the background about which they inspiral is a modification to the Kerr metric, which imprints a CS ...

Science.gov (United States)

The Wind Energy Research Division of Sandia National Laboratories has been funded by the Wind/Ocean Technology Division of the Department of Energy (DOE) to design and build a 34-meter diameter Vertical Axis Wind Turbine (VAWT). The turbine design incorporates the results of recent VAWT research in aerodynamics and structural dynamics. Initial system concept studies identified several blade options that met the required power rating of 500 kW. The final blade and rotor configurations were chosen based on finite element calculations that determined the turbine modes of response, their frequency of vibration, and stress levels. For parked survival turbine components were designed to with stand the loading of a 150 mph (67.0 m/s) wind coupled with maximum cable tensions. Specific areas of design discussed include the rotor, cables, bearings, brakes, and foundations. Construction of the turbine is in progress at this time and anticipated completion ...

Energy Technology Data Exchange (ETDEWEB)

This report of progress and future objectives timetable is based on an included schematic of goals and objectives and the project abstract which is included as Appendix 1. Five matters are summarized in the order of (1) novel methods of calcified bone confocal microscopy and reconstruction image analysis of decalcified beagle and human cortical bone serial sections, (2) macroscopic cross-correlation of beagle and human cortical and cancellous bone fractions with CT analysis, (3) guidance to the most radiobiologically important skeletal regions of interest with the just completed {sup 90}Sr bone tumor map from life time beagle studies, (4) deposition patterns of radioactive agents that participate in apatite crystal nucleation processes in bone and leave radiation-excited electrons trapped in bone mineral, and (5) the budget period timetable. The discovery that beta particles from {sup 166}Ho (T{sub {1/2}} =26 hr, {beta}{sub max} = 1.8 MeV) phosphonic acid bone ...

International Nuclear Information System (INIS)

Interest in renewable energy systems that employ regenerative components to enable intermittent energy sources to service time varying loads is growing. The overall performance of these systems is intimately linked to the choice of the energy storage media and the efficiency of the energy conversion devices. Recent advances in electrolyser and fuel cell technologies may make small-scale hydrogen buffered renewable energy systems a practical reality in the near term. A research team at the University of Victoria - Institute for Integrated Energy Systems (IESVic) is developing a flexible distributed, laboratory-scale energy system called IRENE (Integrated Renewable Energy Experiment). The initial goal of this research is to explore the potential for constructing a regenerative energy system using early commercial and precommercial hydrogen storage and fuel cell energy conversion devices. Once implemented, research efforts will focus on the dynamic interactions ...

Energy Technology Data Exchange (ETDEWEB)

We numerically constructed elementary phase-correct global quantum gates by using molecular electronic and vibrational states to encode two qubits and implement the Deutsch-Jozsa algorithm. The calculations were based on optimal control theory (OCT). The molecular species we chose were Na{sub 2} and Li{sub 2}. The electronic X{sup 1}{sigma}{sub g}{sup +} and A{sup 1}{sigma}{sub u}{sup +} states were taken as two orthonormalized energy levels of the electronic qubit. The vibrational qubits were those involved in these electronic states. The time duration of the optimized pulses with high fidelity was typically 500-900 fs, which reflects the wavepacket dynamics in electronically ground and excited states. When implementing the Deutsch-Jozsa algorithm by combining these elementary gates, we obtained a maximum probability 83.12% for Li{sub 2} molecule, which indicates that the electronic-vibrational qubits are worse than the vibrational-vibrational ...

Energy Technology Data Exchange (ETDEWEB)

In the Energy Balance Analysis Model (Standard Review Plan (USNRC, 1981), Section 3.6.2, ''Determination of Rupture Locations and Dynamic Effects Associated with the Postulated Rupture of Piping''), time dependence is not considered, and a constant blowdown thrust force is assumed. This force includes an amplification factor of 1.1 to account for potential effects of rebound. Many of the assumptions used in establishing the acceptance criteria, as stated in the Standard Review Plan, were based on engineering judgment and logic intended to assure upper bound design rather than on a mechanistic assessment of actual pipe rupture phenomena and their effects. As a result of the current practice an exceedingly conservative design may be introduced. This report represents a parametric study of the amplification factor to account for rebound effects in the Energy Balance Method. Of the 71 distinct cases we chose for ...

Energy Technology Data Exchange (ETDEWEB)

Excessive erosion of the labyrinth seal of a 100 MW geothermal turbine has been investigated. This study used computational fluid dynamics (CFD) and aims to identify one cause of erosion and a possible solution for substantially reducing it. The predictions were based upon a numerical calculation using a CFD model of the labyrinth seal with a water/steam flow containing hard solid particles and solved with a commercial CFD code: Fluent V5.0. The results confirmed the existence of flow conditions that play a major role in the rotor labyrinth seal erosion. Afterwards, the flow path was simulated with changes of rotor labyrinth seal geometry, which are indeed feasible of being implemented. The results confirmed that it is possible to reduce the erosion process by approximately 80% by incorporating a steam flow deflector in the fourth stage diaphragm, which changes the steam flow direction in the inlet zone to the rotor labyrinth seal channel, ...

Energy Technology Data Exchange (ETDEWEB)

Glacier fluctuations exclusively due to internal variations in the climate system are simulated using downscaled integrations of the ECHAM4/OPYC coupled general circulation model (GCM). A process-based modeling approach using a mass balance model of intermediate complexity and a dynamic ice flow model considering simple shearing flow and sliding are applied. Multi-millennia records of glacier length fluctuations for Nigardsbreen (Norway) and Rhonegletscher (Switzerland) are simulated using auto-regressive processes determined by statistically downscaled GCM experiments. Return periods and probabilities of specific glacier length changes using GCM integrations excluding external forcings such as solar irradiation changes, volcanic or anthropogenic effects are analyzed and compared to historical glacier length records. Preindustrial fluctuations of the glaciers as far as observed or reconstructed, including their advance during the ...

CERN Document Server

In dissipative ordinary differential equation systems different time scales cause anisotropic phase volume contraction along solution trajectories. Model reduction methods exploit this for simplifying chemical kinetics via a time scale separation into fast and slow modes. The aim is to approximate the system dynamics with a dimension-reduced model after eliminating the fast modes by enslaving them to the slow ones via computation of a slow attracting manifold. We present a novel method for computing approximations of such manifolds using trajectory-based optimization. We discuss Riemannian geometry concepts as a basis for suitable optimization criteria characterizing trajectories near slow attracting manifolds and thus provide insight into fundamental geometric properties of multiple time scale chemical kinetics. The optimization criteria correspond to a suitable mathematical formulation of "minimal relaxation" of chemical forces along reaction ...

Energy Technology Data Exchange (ETDEWEB)

A three-dimensional mathematical model has been developed as a tool for furnace structure design and operation conditions optimization when the straw combustion is in oxygen-enriched or conventional air atmospheres. Mathematical methods have been used based on a combination of FLIC (A fluid Dynamic Incinerator Code) code for the in-bed incineration and commercial software FLUENT for the over-bed combustion. Oxygen-enriched atmospheres promote the destruction of most pollutants due to the high oxygen partial pressures and temperatures, which is reflected by very low residual amounts of organic combustion by-products in the bottom ash and flue gas of the straw-fired boiler unit. The predictions indicated that the maximum combustion temperature is around 1500 K, CO emission is 201 vppm and O{sub 2} concentration is about 6.9 vol% at furnace exit, and it is shown that mathematical models can serve as a reliable tool for detailed analysis of straw ...

International Nuclear Information System (INIS)

The EUROTRAC sub-project ''Tropospheric Ozone Research'' (TOR) follows a dual strategy: - Observation of the chemical processes contributing to the oxygen balance directly in the atmosphere; - Establishment of a validated data base for model calculations. Both tasks require simultaneous measurements of a wide range of chemical and meteorological components. In the case of the investigation of the chemical processes, it is also desirable to measure the free radicals directly involved in ozone production. In the project described, a measuring station was set up. For a period of two years and a half, continuous measurements were made of ozone and its chemical precursors (NO, NO_2, NO_y, VOC, CO), as well as other photooxidants (H_2O_2 and organic hydroperoxides, organic nitrates), the photolysis frequency of NO_2, and meteorological parameters (wind, temperature, moisture, aerosols). The station was located on the Schauinsland mountain in the southern Black Forest, at ...

International Nuclear Information System (INIS)

The liberalization of the electricity sector requires utilities to develop sound operation strategies for their power plants. In this paper, attention is focused on the problem of optimizing the management of the thermal power plants belonging to a strategic producer that competes with other strategic companies and a set of smaller non-strategic ones in the day-ahead market. The market model suggested here determines an equilibrium condition over the selected period of analysis, in which no producer can increase profits by changing its supply offers given all rivals' bids. Power plants technical and operating constraints are considered. An iterative procedure, based on the dynamic programming, is used to find the optimum production plans of each producer. Some combinations of power plants and number of producers are analyzed, to simulate for instance the decommissioning of old expensive power plants, the installation of new more efficient ...

Energy Technology Data Exchange (ETDEWEB)

In machine condition monitoring many fault-related vibration signals are highly non-stationary. Time-frequency representations comprise the natural signal-processing tool traditionally used for representing such non-stationary signals. The methods used in this analysis are based on the second order statistics of a signal. This paper discusses the use of higher order time frequency methods in the context of a condition monitoring application. The paper outlines the two classes of higher order representations: the L-Wigner distribution and the sliced Wigner higher order distribution. The use of higher order distributions introduces the possibility of non-oscillating cross-terms, a problem not encountered in conventional bilinear time-frequency methods. Techniques for reducing these cross-terms are presented. The paper compares the performance of bilinear and higher order time-frequency methods using synthetic data and vibration signals measured on the engine block of ...

CERN Document Server

From this vast subject, I will pick out and review three specific topics, namely the formation and evolution of bars, the formation of bulges, and the evolution during multiple major mergers. Bars form naturally in galactic discs. Their evolution is driven by the exchange of angular momentum within the galaxy. This is emitted mainly by near-resonant material in the inner disc (bar), and is absorbed by near-resonant material in the outer disc and in the halo. As a result of this, the bar becomes stronger and rotates slower. Bulges are not a homogeneous class of objects. Based on their formation history, one can distinguish three types. Classical bulges are mainly formed before the actual disc component, from collapses or mergers and the corresponding dissipative processes. Boxy/peanut bulges are parts of bars seen edge-on. Finally, disc-like bulges are formed by the inflow of material to the center due to bar torques. Major mergers bring strong and fast evolution ...

International Nuclear Information System (INIS)

This study concerns our experiences with abdominal gamma imaging using Tc-99m colloid and with abdominal angiography using Tc-99m-pyrophosphate labelled erythrocytes ''in vivo'' based on the modified technique described by Callahan. The dynamic or perfusion phase was first performed, then the static phase during which for the first two hours scans were taken every 15 minutes and thereafter every 4-6 hours. The routine image corresponds to the first, although it was necessary at times to take oblique projections. The study was felt to be accomplished after 48 hours upon observing no extravasation of radioactive material in the abdominal region, or upon detecting a bleeding site. The investigation was performed on 11 patients, 8 having positive scans of abdominal extravasation, later confirmed in 6 by endoscopy and by surgery. In 2, the presence of salmonelosis was shown by laboratory analysis. Endoscopy and angiography XR are both invasor ...

Energy Technology Data Exchange (ETDEWEB)

A new double-null, slotted divertor configuration will be installed for the DIII-D Radiative Divertor Program at General Atomics in late 1996. Four cryocondensation pumps, three new and one existing, will be part of this new divertor. The purpose of the pumps is to provide plasma density control and to limit the impurities entering the plasma core by providing pumping at each divertor strike point. The three new pumps are based on the design of the existing pump, installed in 1992 as part of the Advanced Divertor Program. The new pumps require geometry modifications to the original design. Therefore, extensive modal and dynamic analyses were performed to determine the behavior of these pumps and their helium and nitrogen feed lines during disruption events. Thermal and fluid analyses were also performed to characterize the helium two-phase flow regime in the pumps and their feedlines. A flow testing program was completed to test the change in ...

Energy Technology Data Exchange (ETDEWEB)

The application of HVDC system to the trunk power supply system requires the transmission of DC power as much as possible to improve the stability of the whole AC/DC system. To meet this requirement, continued pulse system, which keeps sending a DC current even when an AC voltage lowers remarkably, has been used. The stability is much more improved by adding damping control which modulates converter active and/or reactive power. In order to make full use of such control effects, it is important that the HVDC system maintains stable operation during faults and reclosing of the AC system. In particular, it is necessary to prevent a repetitive commutation failure following the unbalanced AC transmission line faults. In this paper, the cause of the repetitive commutation failure is discussed by using the AC-DC power system simulator developed by CRIEPI. Based on the analytical result, a stabilization control scheme with on-line extinction angle estimation is proposed, ...

International Nuclear Information System (INIS)

Plasma surface interactions in tokamaks are known to create significant quantities of dust, which settles onto surfaces and accumulates in the vacuum vessel. In ITER, a loss of vacuum accident may result in the release of dust which will be radioactive and/or toxic, and provides increased surface area for chemical reactions or dust explosion. A new method of analysis has been developed for modeling dust resuspension and transport in loss of vacuum accidents. The aerosol dynamic equation is solved via the user defined scalar (UDS) capability in the commercial CFD code Fluent. Fluent solves up to 50 generic transport equations for user defined scalars, and allows customization of terms in these equations through user defined functions (UDF). This allows calculation of diffusion coefficients based on local flow properties, inclusion of body forces such as gravity and thermophoresis in the convection term, and user defined source terms. The code ...

Energy Technology Data Exchange (ETDEWEB)

Power system operating conditions vary with system configurations and loading conditions. Coefficients in nominal system model change in a complex manner with different operating point and so does system dynamic behavior. With the aid of unstructured and structured uncertainty descriptions, the worst system variations can be estimated and formulated into two different uncertainty models in frequency domain; multiplicative unstructured uncertainty in the form of transfer function and structured uncertainty with the parametric uncertainty description. The uncertainty descriptions are then incorporated into system nominal model to perform H{sub {infinity}} and {mu} based robust power system stabilizer (PSS) design. Both approaches to the PSS design enable the power system to remain stable over a wide range of system operating conditions but the different performance can be observed due to the inheritance of the ways to handle the system ...

Energy Technology Data Exchange (ETDEWEB)

The computer aided coal structure construction system is proposed, and a computational construction example is presented. The coal structure construction engine of this system fabricates molecular structure by connecting fragments sequentially inputted through a user interface. The best structure candidate is determined using construction knowledge and partial energy evaluation every addition of one fragment, and this process is subsequently repeated. The structure evaluation engine analyzes the 3-D conformation candidate by molecular dynamics, and evaluates the conformation by determining the energy value of an optimum structure. As an example, this system was applied to construction of coal molecular structure based on the actual data of partial structure composed of 26 structures from 2l kinds of aromatic cluster structures, 27 bonds from 2 kinds of bridged bonds, and 16 groups from 2 kinds of terminal substitutional groups. As a result, ...

Energy Technology Data Exchange (ETDEWEB)

Solid-state nuclear magnetic resonance (NMR) has been used to explore the nanometer-scale structure of Nafion, the widely used fuel cell membrane, and its composites. We have shown that solid-state NMR can characterize chemical structure and composition, domain size and morphology, internuclear distances, molecular dynamics, etc. The newly-developed water channel model of Nafion has been confirmed, and important characteristic length-scales established. Nafion-based organic and inorganic composites with special properties have also been characterized and their structures elucidated. The morphology of Nafion varies with hydration level, and is reflected in the changes in surface-to-volume (S/V) ratio of the polymer obtained by small-angle X-ray scattering (SAXS). The S/V ratios of different Nafion models have been evaluated numerically. It has been found that only the water channel model gives the measured S/V ratios in the normal hydration ...

CERN Document Server

We consider network coding for networks experiencing worst-case bit-flip errors, and argue that this is a reasonable model for highly dynamic wireless network transmissions. We demonstrate that in this setup prior network error-correcting schemes can be arbitrarily far from achieving the optimal network throughput. We propose a new metric for errors under this model. Using this metric, we prove a new Hamming-type upper bound on the network capacity. We also show a commensurate lower bound based on GV-type codes that can be used for error-correction. The codes used to attain the lower bound are non-coherent (do not require prior knowledge of network topology). The end-to-end nature of our design enables our codes to be overlaid on classical distributed random linear network codes. Further, we free internal nodes from having to implement potentially computationally intensive link-by-link error-correction.

Energy Technology Data Exchange (ETDEWEB)

The application of the LBB technology to the newly constructed PWRs has been approved in Korea for several high energy systems that can meet rigorous acceptance criteria. The LBB evaluation had been initiated for Yong-Gwang 3 and 4 units (YGN 3 and 4) which are in service, and subsequently performed for Ul-Chin 3 and 4 units (UCN 3 and 4) which are in construction. The LBB application in Korea is based on the USNRC requirements. The LBB evaluation for YGN 3 and 4 is to eliminate the dynamic effects associated with the postulated DEGB from design basis loads as well as to eliminate pipe whip restraints and jet impingement barriers. There were several issues on the application of LBB to the primary coolant loop and the pressurizer surge line. Of concern were material properties of carbon steel for the primary coolant loop, estimation of crack opening area at the pipe-to-nozzle interface considering the asymmetry, and the leakage crack size which ...