International Nuclear Information System (INIS)
Kim, Du Gi
2005-08-01
This book introduces summary of structural dynamics, the reason of learning of structural dynamics, single-degree of freedom system, simple harmonic vibration and application, numerical analysis method, such as time domain and frequency domain and nonlinear system, multi-degree of freedom system random vibration over discrete distribution, continuous distribution and extreme value distribution, circumstance vibration, earth quake vibration, including input earthquake, and earthquake-resistant design and capacity spectrum method, wind oscillation wave vibration, vibration control and maintenance control.
Strømmen, Einar N
2014-01-01
This book introduces to the theory of structural dynamics, with focus on civil engineering structures that may be described by line-like beam or beam-column type of systems, or by a system of rectangular plates. Throughout this book the mathematical presentation contains a classical analytical description as well as a description in a discrete finite element format, covering the mathematical development from basic assumptions to the final equations ready for practical dynamic response predictions. Solutions are presented in time domain as well as in frequency domain. Structural Dynamics starts off at a basic level and step by step brings the reader up to a level where the necessary safety considerations to wind or horizontal ground motion induced dynamic design problems can be performed. The special theory of the tuned mass damper has been given a comprehensive treatment, as this is a theory not fully covered elsewhere. For the same reason a chapter on the problem of moving loads on beams has been included.
DEFF Research Database (Denmark)
Nielsen, Søren R.K.
The present textbook has been written for a course on stochastic vibration theory that is being given on the 9th semester at Aalborg University for M.Sc. students in structural engineering.......The present textbook has been written for a course on stochastic vibration theory that is being given on the 9th semester at Aalborg University for M.Sc. students in structural engineering....
Fundamentals of structural dynamics
Craig, Roy R
2006-01-01
From theory and fundamentals to the latest advances in computational and experimental modal analysis, this is the definitive, updated reference on structural dynamics.This edition updates Professor Craig's classic introduction to structural dynamics, which has been an invaluable resource for practicing engineers and a textbook for undergraduate and graduate courses in vibrations and/or structural dynamics. Along with comprehensive coverage of structural dynamics fundamentals, finite-element-based computational methods, and dynamic testing methods, this Second Edition includes new and e
Structure, Reactivity and Dynamics
Indian Academy of Sciences (India)
Understanding structure, reactivity and dynamics is the core issue in chemical ... functional theory (DFT) calculations, molecular dynamics (MD) simulations, light- ... between water and protein oxygen atoms, the superionic conductors which ...
Structural Dynamics Laboratory (SDL)
Federal Laboratory Consortium — Structural dynamic testing is performed to verify the survivability of a component or assembly when exposed to vibration stress screening, or a controlled simulation...
Anderson, James C
2012-01-01
A concise introduction to structural dynamics and earthquake engineering Basic Structural Dynamics serves as a fundamental introduction to the topic of structural dynamics. Covering single and multiple-degree-of-freedom systems while providing an introduction to earthquake engineering, the book keeps the coverage succinct and on topic at a level that is appropriate for undergraduate and graduate students. Through dozens of worked examples based on actual structures, it also introduces readers to MATLAB, a powerful software for solving both simple and complex structural d
DEFF Research Database (Denmark)
Nielsen, Søren R.K.
This book has been prepared for the course on Computational Dynamics given at the 8th semester at the structural program in civil engineering at Aalborg University.......This book has been prepared for the course on Computational Dynamics given at the 8th semester at the structural program in civil engineering at Aalborg University....
Dynamic interactions of the cortical networks during thought suppression.
Aso, Toshihiko; Nishimura, Kazuo; Kiyonaka, Takashi; Aoki, Takaaki; Inagawa, Michiyo; Matsuhashi, Masao; Tobinaga, Yoshikazu; Fukuyama, Hidenao
2016-08-01
Thought suppression has spurred extensive research in clinical and preclinical fields, particularly with regard to the paradoxical aspects of this behavior. However, the involvement of the brain's inhibitory system in the dynamics underlying the continuous effort to suppress thoughts has yet to be clarified. This study aims to provide a unified perspective for the volitional suppression of internal events incorporating the current understanding of the brain's inhibitory system. Twenty healthy volunteers underwent functional magnetic resonance imaging while they performed thought suppression blocks alternating with visual imagery blocks. The whole dataset was decomposed by group-independent component analysis into 30 components. After discarding noise components, the 20 valid components were subjected to further analysis of their temporal properties including task-relatedness and between-component residual correlation. Combining a long task period and a data-driven approach, we observed a right-side-dominant, lateral frontoparietal network to be strongly suppression related. This network exhibited increased fluctuation during suppression, which is compatible with the well-known difficulty of suppression maintenance. Between-network correlation provided further insight into the coordinated engagement of the executive control and dorsal attention networks, as well as the reciprocal activation of imagery-related components, thus revealing neural substrates associated with the rivalry between intrusive thoughts and the suppression process.
Nonlinear dynamics of structures
Oller, Sergio
2014-01-01
This book lays the foundation of knowledge that will allow a better understanding of nonlinear phenomena that occur in structural dynamics. This work is intended for graduate engineering students who want to expand their knowledge on the dynamic behavior of structures, specifically in the nonlinear field, by presenting the basis of dynamic balance in non‐linear behavior structures due to the material and kinematics mechanical effects. Particularly, this publication shows the solution of the equation of dynamic equilibrium for structure with nonlinear time‐independent materials (plasticity, damage and frequencies evolution), as well as those time dependent non‐linear behavior materials (viscoelasticity and viscoplasticity). The convergence conditions for the non‐linear dynamic structure solution are studied, and the theoretical concepts and its programming algorithms are presented.
Evidence of ghost suppression in gluon mass scale dynamics
Aguilar, A. C.; Binosi, D.; Figueiredo, C. T.; Papavassiliou, J.
2018-03-01
In this work we study the impact that the ghost sector of pure Yang-Mills theories may have on the generation of a dynamical gauge boson mass scale, which hinges on the appearance of massless poles in the fundamental vertices of the theory, and the subsequent realization of the well-known Schwinger mechanism. The process responsible for the formation of such structures is itself dynamical in nature, and is governed by a set of Bethe-Salpeter type of integral equations. While in previous studies the presence of massless poles was assumed to be exclusively associated with the background-gauge three-gluon vertex, in the present analysis we allow them to appear also in the corresponding ghost-gluon vertex. The full analysis of the resulting Bethe-Salpeter system reveals that the contribution of the poles associated with the ghost-gluon vertex are particularly suppressed, their sole discernible effect being a slight modification in the running of the gluon mass scale, for momenta larger than a few GeV. In addition, we examine the behavior of the (background-gauge) ghost-gluon vertex in the limit of vanishing ghost momentum, and derive the corresponding version of Taylor's theorem. These considerations, together with a suitable Ansatz, permit us the full reconstruction of the pole sector of the two vertices involved.
Wildfire and drought dynamics destabilize carbon stores of fire-suppressed forests
J. Mason Earles; Malcolm P. North; Matthew D. Hurteau
2014-01-01
Widespread fire suppression and thinning have altered the structure and composition of many forests in the western United States, making them more susceptible to the synergy of large-scale drought and fire events. We examine how these changes affect carbon storage and stability compared to historic fire-adapted conditions. We modeled carbon dynamics under possible...
DEFF Research Database (Denmark)
Andreasen, Martin Møller; Meldrum, Andrew
This paper studies whether dynamic term structure models for US nominal bond yields should enforce the zero lower bound by a quadratic policy rate or a shadow rate specification. We address the question by estimating quadratic term structure models (QTSMs) and shadow rate models with at most four...
Binocular vision in amblyopia : structure, suppression and plasticity
Hess, Robert F; Thompson, Benjamin; Baker, Daniel Hart
2014-01-01
The amblyopic visual system was once considered to be structurally monocular. However, it now evident that the capacity for binocular vision is present in many observers with amblyopia. This has led to new techniques for quantifying suppression that have provided insights into the relationship between suppression and the monocular and binocular visual deficits experienced by amblyopes. Furthermore, new treatments are emerging that directly target suppressive interactions within the visual cor...
International Nuclear Information System (INIS)
Bhoje, S.B.
2003-01-01
In view of thin walled large diameter shell structures with associated fluid effects, structural dynamics problems are very critical in a fast breeder reactor. Structural characteristics and consequent structural dynamics problems in typical pool type Fast Breeder Reactor are highlighted. A few important structural dynamics problems are pump induced as well as flow induced vibrations, seismic excitations, pressure transients in the intermediate heat exchangers and pipings due to a large sodium water reaction in the steam generator, and core disruptive accident loadings. The vibration problems which call for identification of excitation forces, formulation of special governing equations and detailed analysis with fluid structure interaction and sloshing effects, particularly for the components such as PSP, inner vessel, CP, CSRDM and TB are elaborated. Seismic design issues are presented in a comprehensive way. Other transient loadings which are specific to FBR, resulting from sodium-water reaction and core disruptive accident are highlighted. A few important results of theoretical as well as experimental works carried out for 500 MWe Prototype Fast Breeder Reactor (PFBR), in the domain of structural dynamics are presented. (author)
Paultre, Patrick
2013-01-01
This book covers structural dynamics from a theoretical and algorithmic approach. It covers systems with both single and multiple degrees-of-freedom. Numerous case studies are given to provide the reader with a deeper insight into the practicalities of the area, and the solutions to these case studies are given in terms of real-time and frequency in both geometric and modal spaces. Emphasis is also given to the subject of seismic loading. The text is based on many lectures on the subject of structural dynamics given at numerous institutions and thus will be an accessible and practical aid to
DEFF Research Database (Denmark)
Kejlberg-Rasmussen, Casper
statements about our data structure, which are based on the structure of the underlying problem, that we are trying to solve. We can rely on the properties of the invariants when performing queries, and in return we need to ensure that the invariants remain true after we perform updates. When designing data......In this thesis I will address three dynamic data structure problems using the concept of invariants. The first problem is maintaining a dynamically changing set of keys – a dictionary – where the queries we can ask are: does it contain a given key? and what is the preceding (or succeeding) key...... to a given key? The updates we can do are: inserting a new key or deleting a given key. Our dictionary has the working set property, which means that the running time of a query depends on the query distribution. Specifically the time to search for a key depends on when we last searched for it. Our data...
Binocular vision in amblyopia: structure, suppression and plasticity.
Hess, Robert F; Thompson, Benjamin; Baker, Daniel H
2014-03-01
The amblyopic visual system was once considered to be structurally monocular. However, it now evident that the capacity for binocular vision is present in many observers with amblyopia. This has led to new techniques for quantifying suppression that have provided insights into the relationship between suppression and the monocular and binocular visual deficits experienced by amblyopes. Furthermore, new treatments are emerging that directly target suppressive interactions within the visual cortex and, on the basis of initial data, appear to improve both binocular and monocular visual function, even in adults with amblyopia. The aim of this review is to provide an overview of recent studies that have investigated the structure, measurement and treatment of binocular vision in observers with strabismic, anisometropic and mixed amblyopia. © 2014 The Authors Ophthalmic & Physiological Optics © 2014 The College of Optometrists.
Analysis of a Mark II containment structure for hydrodynamic loads in suppression pool
International Nuclear Information System (INIS)
Bedrosian, B.
1978-01-01
During pressure-relief modes of BWR plant operation forcing signals are introduced into the suppression pool at discrete locations: exit nozzles of SRV discharge pipes (quenchers or ramsheads). These forcing signals are transmitted through the water of the suppression pool and, after reaching the pool boundaries, act as loadings on the containment structure wetted perimeter. The response of the containment structure is influenced by the presence of water as it interacts with the structure during application of the load. An adequate analysis must account for fluid-structure interaction (FSI) effects. This paper presents an exact formulation for solving the problem. FSI effects may become significant for a given geometry if the time history of loading and the dynamic properties of the coupled fluid-structure system satisfy a defined (system related) relationship. Results of analyses and parametric/sensitivity studies performed for the steel containment structure of an 1100 Mwe BWR nuclear plant of Mark II configuration are presented. (Author)
Distributed Dynamic Condition Response Structures
DEFF Research Database (Denmark)
Hildebrandt, Thomas; Mukkamala, Raghava Rao
We present distributed dynamic condition response structures as a declarative process model inspired by the workflow language employed by our industrial partner and conservatively generalizing labelled event structures. The model adds to event structures the possibility to 1) finitely specify...... as a labelled transition system. Exploration of the relationship between dynamic condition response structures and traditional models for concurrency, application to more complex scenarios, and further extensions of the model is left to future work....
Dynamic load in suppression pool during BWR main steam safety relief valve actuation
International Nuclear Information System (INIS)
Tsukada, Hiroshi; Yamaguchi, Hirokatsu; Morita, Terumichi
1979-01-01
BWRs are so designed that the exhaust steam from main steam safety relief valves is led to pressure suppression pools, and the steam is condensed in pool water, but at this time, dynamic load seems to arise in the pool water. In Tokai No. 2 Power Station, a Mark-2 containment vessel was adopted to improve the reliability as much as possible and to obtain the design with margin. In this report, the result of actual machine test in Tokai No. 2 Power Station and the method of reducing the load are described. When a relief valve works, the discharge of water in exhaust pipes into a suppression pool, the exhaust of air in exhaust pipes and repeated expansion and contraction of bubbles in pool water, and the exhaust of steam and condensation occur. As for the construction of the suppression pool in Tokai No. 2 Power Station, cross-shaped quencher and the structure with jet deflector were installed. The test plan and the test result with an actual machine are reported. The soundness of the Mark-2 containment vessel and the structures in the pool was proved. The differential pressure acting on the structures was negligibly small. The measured pulsating pressure was in the range from 0.84 to -0.39 kg/cm 2 . (Kako, I.)
Dynamics of Turbulence Suppression in a Helicon Plasma
Hayes, Tiffany; Gilmore, Mark
2012-10-01
Experiments are currently being conducted in the the Helicon-Cathode Device (HelCat) at the University of New Mexico. The goal is to the study in detail the transition from a turbulent to a non-turbulent state in the presence of flow shear. HelCat has intrinsic fluctuations that have been identified as drift-waves. Using simple electrode biasing, it has been found that these fluctuations can be completely suppressed. In some extreme cases, a different instability, possibly the Kelvin-Helmholtz instability, can be excited. Detailed studies are underway in order to understand the characteristics of each mode, and to elucidate the underlying physics that cause the change between an unstable plasma, and an instability-free plasma. Dynamics being observed include changes in flow profiles, both azimuthal and parallel, as well as changes in potential and temperature gradients. Further understanding is being sought using several computer codes developed at EPFL: a linear stability solver (LSS,footnotetextP. Ricci and B.N. Rogers (2009). Phys Plasmas 16, 062303. a one-dimensional PIC code/sheath solver, ODISEE,footnotetextJ. Loizu, P. Ricci, and C. Theiler (2011). Phys Rev E 83, 016406 and a global, 3D Braginski code, GBS.footnotetextRicci, Rogers (2009) A basic overview of results will be presented.
Dynamic modeling and adaptive vibration suppression of a high-speed macro-micro manipulator
Yang, Yi-ling; Wei, Yan-ding; Lou, Jun-qiang; Fu, Lei; Fang, Sheng; Chen, Te-huan
2018-05-01
This paper presents a dynamic modeling and microscopic vibration suppression for a flexible macro-micro manipulator dedicated to high-speed operation. The manipulator system mainly consists of a macro motion stage and a flexible micromanipulator bonded with one macro-fiber-composite actuator. Based on Hamilton's principle and the Bouc-Wen hysteresis equation, the nonlinear dynamic model is obtained. Then, a hybrid control scheme is proposed to simultaneously suppress the elastic vibration during and after the motor motion. In particular, the hybrid control strategy is composed of a trajectory planning approach and an adaptive variable structure control. Moreover, two optimization indices regarding the comprehensive torques and synthesized vibrations are designed, and the optimal trajectories are acquired using a genetic algorithm. Furthermore, a nonlinear fuzzy regulator is used to adjust the switching gain in the variable structure control. Thus, a fuzzy variable structure control with nonlinear adaptive control law is achieved. A series of experiments are performed to verify the effectiveness and feasibility of the established system model and hybrid control strategy. The excited vibration during the motor motion and the residual vibration after the motor motion are decreased. Meanwhile, the settling time is shortened. Both the manipulation stability and operation efficiency of the manipulator are improved by the proposed hybrid strategy.
Experimental results of active control on a large structure to suppress vibration
Dunn, H. J.
1991-01-01
Three design methods, Linear Quadratic Gaussian with Loop Transfer Recovery (LQG/LTR), H-infinity, and mu-synthesis, are used to obtain compensators for suppressing the vibrations of a 10-bay vertical truss structure, a component typical of what may be used to build a large space structure. For the design process the plant dynamic characteristics of the structure were determined experimentally using an identification method. The resulting compensators were implemented on a digital computer and tested for their ability to suppress the first bending mode response of the 10-bay vertical truss. Time histories of the measured motion are presented, and modal damping obtained during the experiments are compared with analytical predictions. The advantages and disadvantages of using the various design methods are discussed.
Structural dynamic modification
Indian Academy of Sciences (India)
and stiffness matrices) andaor modal parameters, in order to acquire some ... For the above reasons, another modification approach is presented here ... The data necessary to solve the direct problem are dynamic behaviour of the original.
International Nuclear Information System (INIS)
Gabata, Toshifumi
1994-01-01
The efficacy of both fat suppressed T1-weighted imaging (T1WI) and dynamic gadolinium-enhanced MR imaging (dynamic MRI) was compared with conventional MR sequences and dynamic CT in 22 patients with histologically proven pancreatic adenocarcinoma (PAC). In the control group of 30 patients without pancreatic disease, the pancreas was shown as a markedly higher signal intensity on fat suppressed T1WI than on conventional MR sequences. The signal noise ratio (SNR) of the normal pancreas and the contrast noise ratio (CNR) between the normal pancreas and muscle were significantly higher on fat suppressed T1WI than the other MR sequences. In the group of PAC patients without chronic pancreatitis (n=14), CNR between the tumor and the normal pancreas significantly differed among imaging techniques, including fat suppressed T1WI, dynamic MRI, and the other conventional MR sequences. In the group of PAC with chronic pancreatitis (n=8), CNR between the tumor and the associated chronic pancreatitis was remarkably diminished on both fat suppressed T1WI and conventional T1WI; however, it was significantly higher on dynamic MRI than the other pulse sequences. The early phase of dynamic MRI clearly identified the tumors in the group of PAC. The capability of conventional T1WI and dynamic CT to demonstrate peripancreatic tumor extension was significantly higher than that of fat suppressed T1WI. In conclusion, fat suppressed T1WI and dynamic MRI were useful in detecting pancreatic carcinoma. (N.K.)
Dynamic testing of cable structures
Directory of Open Access Journals (Sweden)
Caetano Elsa
2015-01-01
Full Text Available The paper discusses the role of dynamic testing in the study of cable structures. In this context, the identification of cable force based on vibration measurements is discussed. Vibration and damping assessment are then introduced as the focus of dynamic monitoring systems, and particular aspects of the structural behaviour under environmental loads are analysed. Diverse application results are presented to support the discussion centred on cable-stayed bridges, roof structures, a guyed mast and a transmission line.
Nature of dynamical suppressions in the generalized Veneziano model
International Nuclear Information System (INIS)
Odorico, R.
1976-05-01
It is shown by explicit numerical calculations that of a class of coupling suppressions existing in the generalized Veneziano model, which have been recently used to interpret the psi data and other related phenomena, only a part can be attributed to the exponential growth with energy of the number of levels in the model. The remaining suppressions have a more direct dual origin
Structural dynamic modifications via models
Indian Academy of Sciences (India)
The study shows that as many as half of the matrix ... the dynamicist's analytical modelling skill which would appear both in the numerator as. Figure 2. ..... Brandon J A 1990 Strategies for structural dynamic modification (New York: John Wiley).
International Nuclear Information System (INIS)
De Canio, G.; Ranieri, N.
2009-01-01
Shake table tests allow to assess the effectiveness of technologies for structures protection from natural events such as earthquakes. The article summarizes the remarkable results of the most significant projects. [it
DEFF Research Database (Denmark)
Nielsen, Søren R.K.
The present textbook has been written for a course on stochastic vibration theory that is being given on the 9th semester at Aalborg University for M.Sc. students in structural engineering.......The present textbook has been written for a course on stochastic vibration theory that is being given on the 9th semester at Aalborg University for M.Sc. students in structural engineering....
Coupled fluid-structure method for pressure suppression analysis
International Nuclear Information System (INIS)
McMaster, W.H.; Norris, D.M. Jr.; Goudreau, G.L.
1979-01-01
We have coupled an incompressible Eulerian hydrodynamic algorithm to a Lagrangian finite-element shell algorithm for the analysis of pressure suppression in boiling water reactors. The computer program calculates loads and structural response from air and steam blowdown and the oscillating condensation of steam bubbles in a water pool. The fluid, structure, and coupling algorithms have been verified by the calculation of solved problems from the literature and from air and steam blowdown experiments. The foundation of the program is the semi-implicit, two-dimensional SOLA algorithm. The shell structure algorithm uses conventional thin-shell theory with transverse shear. The finite-element spatial discretization employs piecewise-linear interpolation functions and one-point quadrature applied to conical frustra. We use the Newmark implicit time-integration method implemented as a one-step module. The algorithms are strongly coupled in the iteration loop using the iterated pressure in the fluid to drive the structure. The coupling algorithm requires normal velocity compatibility at the fluid-structure interface and incompressibility of the computational Eulerian zone overlaid by the structure. This is accomplished by iterating on the pressure field which is applied to the structure during each iteration until both conditions are satisfied
DEFF Research Database (Denmark)
Tsakalidis, Konstantinos
multi-versioned indexing database. We ﬁrst present a generic method for making data structures fully persistent in external memory. This method can render any database multi-versioned, as long as its implementation abides by our assumptions. We obtain the result by presenting an implementation of B...
Cantat, Isabelle; Graner, François; Pitois, Olivier; Höhler, Reinard; Elias, Florence; Saint-Jalmes, Arnaud; Rouyer, Florence
2013-01-01
This book is the first to provide a thorough description of all aspects of the physico-chemical properties of foams. It sets out what is known about their structure, their stability, and their rheology. Engineers, researchers and students will find descriptions of all the key concepts, illustrated by numerous applications, as well as experiments and exercises for the reader. A solutions manual for lecturers is available via the publisher's web site.
Past and future trends in structures and dynamics
International Nuclear Information System (INIS)
Bader, R.M.; Goesch, W.H.; Olsen, J.J.
1981-01-01
An historical review and a series of prognostications based on current developments are presented for the fields of structural design and structural dynamics analysis. It is shown that while weight and cost reduction and improved durability have been the primary forces in structural technology development in the past, emphasis has shifted to such things as productivity, quality assurance, low observables for military aircraft and increased fuel efficiency. Prominent among recent advances in future developments are damage tolerance durability, computer-aided design, active flutter suppression, adhesive bonding of primary structures, cast aluminum structures, titanium and graphite-epoxy primary aircraft structures, aeroelastic tailoring composites, metal matrix composites, and radar-absorbing structures
Coherent structures and dynamical systems
Jimenez, Javier
1987-01-01
Any flow of a viscous fluid has a finite number of degrees of freedom, and can therefore be seen as a dynamical system. A coherent structure can be thought of as a lower dimensional manifold in whose neighborhood the dynamical system spends a substantial fraction of its time. If such a manifold exists, and if its dimensionality is substantially lower that that of the full flow, it is conceivable that the flow could be described in terms of the reduced set of degrees of freedom, and that such a description would be simpler than one in which the existence of structure was not recognized. Several examples are briefly summarized.
Relating structure and dynamics in organisation models
Jonkers, C.M.; Treur, J.
2002-01-01
To understand how an organisational structure relates to dynamics is an interesting fundamental challenge in the area of social modelling. Specifications of organisational structure usually have a diagrammatic form that abstracts from more detailed dynamics. Dynamic properties of agent systems,
Kehrein, Stephan; Kohnen, Thomas; Fronius, Maria
2016-06-01
Interocular suppression is assumed to be the mechanism leading to impaired visual acuity, especially in strabismic amblyopia. Little is known about the dynamics of suppression during treatment. The aim of our study was to assess the development of the depth of suppression and its relation to changes in visual acuity during electronically monitored occlusion treatment. In a prospective pilot study, 15 amblyopes (8 with and 7 without strabismus) aged 5 to 16 years (mean 10.24 years) were examined before initiation of patching and then every 3 to 6 weeks for 4 months. To quantify suppression, a red filter ladder (Sbisa bar) was used, attenuating the image of the dominant eye until the patients reported a binocular perception (diplopia, rivalry, color mixture) or a change in eye dominance. Acuity was assessed with crowded Landolt rings. Daily occlusion was recorded using occlusion dose monitors. The depth of interocular suppression showed a biphasic change: it increased significantly during the first month (P=0.02), while visual acuity improved (mean 0.14 log units ±0.13; Pocclusion and suppression changes was not statistically significant. This first insight into the functional changes during electronically monitored patching suggests a complex relationship between visual acuity and interocular suppression that seems to be influenced by the presence of strabismus. Knowledge of the dynamics of interocular suppression is crucial for enhancing the outcome of occlusion treatment and also for the evaluation of its future role compared to emerging dichoptic treatments.
Static and Dynamic Membrane Structures
Directory of Open Access Journals (Sweden)
Sergiu Ivanov
2012-10-01
Full Text Available While originally P systems were defined to contain multiset rewriting rules, it turned out that considering different types of rules may produce important results, such as increasing the computational power of the rules. This paper focuses on factoring out the concept of a membrane structure out of various P system models with the goal of providing useful formalisations. Both static and dynamic membrane structures are considered.
Can a static nonlinearity account for the dynamics of otoacoustic emission suppression?
DEFF Research Database (Denmark)
Verhulst, Sarah; Shera, Christopher A.; Harte, James
2011-01-01
This study investigates whether time-dependent compression mechanisms in the cochlea are necessary to explain dynamic properties of otoacoustic emissions (OAEs). Dynamic properties of click-evoked OAEs (CEOAEs) have been observed in temporal suppression; the effect where the CEOAE magnitude is re...
Structural system identification: Structural dynamics model validation
Energy Technology Data Exchange (ETDEWEB)
Red-Horse, J.R.
1997-04-01
Structural system identification is concerned with the development of systematic procedures and tools for developing predictive analytical models based on a physical structure`s dynamic response characteristics. It is a multidisciplinary process that involves the ability (1) to define high fidelity physics-based analysis models, (2) to acquire accurate test-derived information for physical specimens using diagnostic experiments, (3) to validate the numerical simulation model by reconciling differences that inevitably exist between the analysis model and the experimental data, and (4) to quantify uncertainties in the final system models and subsequent numerical simulations. The goal of this project was to develop structural system identification techniques and software suitable for both research and production applications in code and model validation.
Analysis of Nonlinear Dynamic Structures
African Journals Online (AJOL)
Bheema
work a two degrees of freedom nonlinear system with zero memory was ... FRF is the most widely used method in structural dynamics which gives information about the ..... 3.6, which is the waterfall diagram of the same response, as well.
Error suppression and error correction in adiabatic quantum computation: non-equilibrium dynamics
International Nuclear Information System (INIS)
Sarovar, Mohan; Young, Kevin C
2013-01-01
While adiabatic quantum computing (AQC) has some robustness to noise and decoherence, it is widely believed that encoding, error suppression and error correction will be required to scale AQC to large problem sizes. Previous works have established at least two different techniques for error suppression in AQC. In this paper we derive a model for describing the dynamics of encoded AQC and show that previous constructions for error suppression can be unified with this dynamical model. In addition, the model clarifies the mechanisms of error suppression and allows the identification of its weaknesses. In the second half of the paper, we utilize our description of non-equilibrium dynamics in encoded AQC to construct methods for error correction in AQC by cooling local degrees of freedom (qubits). While this is shown to be possible in principle, we also identify the key challenge to this approach: the requirement of high-weight Hamiltonians. Finally, we use our dynamical model to perform a simplified thermal stability analysis of concatenated-stabilizer-code encoded many-body systems for AQC or quantum memories. This work is a companion paper to ‘Error suppression and error correction in adiabatic quantum computation: techniques and challenges (2013 Phys. Rev. X 3 041013)’, which provides a quantum information perspective on the techniques and limitations of error suppression and correction in AQC. In this paper we couch the same results within a dynamical framework, which allows for a detailed analysis of the non-equilibrium dynamics of error suppression and correction in encoded AQC. (paper)
Meng, Deshan; Wang, Xueqian; Xu, Wenfu; Liang, Bin
2017-05-01
For a space robot with flexible appendages, vibrations of flexible structure can be easily excited during both orbit and/or attitude maneuvers of the base and the operation of the manipulators. Hence, the pose (position and attitude) of the manipulator's end-effector will greatly deviate from the desired values, and furthermore, the motion of the manipulator will trigger and exacerbate vibrations of flexible appendages. Given lack of the atmospheric damping in orbit, the vibrations will last for quite a while and cause the on-orbital tasks to fail. We derived the rigid-flexible coupling dynamics of a space robot system with flexible appendages and established a coupling model between the flexible base and the space manipulator. A specific index was defined to measure the coupling degree between the flexible motion of the appendages and the rigid motion of the end-effector. Then, we analyzed the dynamic coupling for different conditions, such as modal displacements, joint angles (manipulator configuration), and mass properties. Moreover, the coupling map was adopted and drawn to represent the coupling motion. Based on this map, a trajectory planning method was addressed to suppress structure vibration. Finally, simulation studies of typical cases were performed, which verified the proposed models and method. This work provides a theoretic basis for the system design, performance evaluation, trajectory planning, and control of such space robots.
International Nuclear Information System (INIS)
Miletich, R.S.
1985-01-01
The effects of pergolide, a direct dopamine receptor agonist, on sleep and wakefulness, motor behavior and 3 H-spiperone specific binding in limbic structures and striatum in rats was studied. The results show that pergolide induced a biphasic dose effect, with high doses increasing wakefulness and suppressing sleep while low dose decreased wakefulness, but increased sleep. It was shown that pergolide-induced sleep suppression was blocked by α-glupenthixol and pimozide, two dopamine receptor antagonists. It was further shown that pergolide merely delayed the rebound resulting from rapid-eye-movement (REM) sleep deprivation, that dopamine receptors stimulation had no direct effect on the period, phase or amplitude of the circadian rhythm of REM sleep propensity and that there was no alteration in the coupling of REM sleep episodes with S 2 episodes. Rapid-eye-movement sleep deprivation resulted in increased sensitivity to the pergolide-induced wakefulness stimulation and sleep suppression and pergolide-induced motor behaviors of locomotion and head bobbing. 3 H-spiperone specific binding to dopamine receptors was shown to be altered by REM sleep deprivation in the subcortical limbic structures. It is concluded that the REM sleep suppressing action of dopamine receptor stimulation is secondary to sleep suppression per se and not secondary to a unique effect on the REM sleep. Further, it is suggested that the wakefulness stimulating action of dopamine receptor agonists is mediated by activation of the dopamine receptors in the terminal areas of the mesolimbocortical dopamine projection system
Value of fat suppression and dynamic contrast-enhanced MRI in the diagnosis of insulinoma
International Nuclear Information System (INIS)
Xu Zengbin; Ruan Lingxiang; Peng Zhiyi; Zhang Minming; Xu Shunliang; Zhang Xidao
2003-01-01
Objective: To evaluate the value of fat suppression and dynamic contrast-enhanced MRI in the preoperative localization of insulinoma. Methods: Twelve cases with pathologically proven insulinoma were evaluated with MRI. SE T 1 WI, FSE T 2 WI, T 1 WI and T 2 WI with fat suppression, dynamic contrast-enhanced FMPSPGR sequences were used in MR scanning. Results: On SE T 1 WI, the lesions displayed hypointense in 4, isointense in 8 cases. Lesions showed hyperintense in 4, isointense in 8 cases on FSE T 2 WI. In contrast, 7 cases appeared as hypointense on T 1 WI with fat suppression and 6 cases appeared as hyperintense on T 2 WI with fat suppression. With dynamic contrast-enhanced FMPSPGR sequence 11 of 12 insulinomas were detected. In the arterial phase, the lesions presented as hyperintense with different degrees in 11 cases and isointense in 1 case. 6 cases remained hyperintense and 6 cases were isointense in pancreatic parenchymal and portal phase. 4 lesions were identified only in dynamic enhancement images. The diagnostic accuracy of insulinoma by dynamic contrast-enhanced MRI was 91.7% (11/12) as compared with histological study. Conclusion: The results indicate that dynamic contrast-enhanced MRI is an sensitive and accurate method for the preoperative localization of insulinoma
Dynamic Soil-Structure-Interaction
DEFF Research Database (Denmark)
Kellezi, Lindita
1998-01-01
The aim of this thesis is to investigate and develop alternative methods of analyzing problems in dynamic soil-structure-interaction. The main focus is the major difficulty posed by such an analysis - the phenomenon of waves which radiate outward from the excited structures towards infinity....... In numerical calculations, only a finite region of the foundation metium is analyzed and something is done to prevent the outgoing radiating waves to reflect from the regions's boundary. The prosent work concerns itself with the study of such effects, using the finite element method, and artificial...... transmitting boundary at the edges of the computational mesh. To start with, an investigation of the main effects of the interaction phenomena is carried out employing a widely used model, considering dynamic stiffness of the unbounded soil as frequency independent. Then a complete description...
Directory of Open Access Journals (Sweden)
Olga Azarenko
Full Text Available Consumption of cruciferous vegetables is associated with reduced risk of various types of cancer. Isothiocyanates including sulforaphane and erucin are believed to be responsible for this activity. Erucin [1-isothiocyanato-4-(methylthiobutane], which is metabolically and structurally related to sulforaphane, is present in large quantities in arugula (Eruca sativa, Mill., kohlrabi and Chinese cabbage. However, its cancer preventive mechanisms remain poorly understood. We found that erucin inhibits proliferation of MCF7 breast cancer cells (IC50 = 28 µM in parallel with cell cycle arrest at mitosis (IC50 = 13 µM and apoptosis, by a mechanism consistent with impairment of microtubule dynamics. Concentrations of 5-15 µM erucin suppressed the dynamic instability of microtubules during interphase in the cells. Most dynamic instability parameters were inhibited, including the rates and extents of growing and shortening, the switching frequencies between growing and shortening, and the overall dynamicity. Much higher erucin concentrations were required to reduce the microtubule polymer mass. In addition, erucin suppressed dynamic instability of microtubules reassembled from purified tubulin in similar fashion. The effects of erucin on microtubule dynamics, like those of sulforaphane, are similar qualitatively to those of much more powerful clinically-used microtubule-targeting anticancer drugs, including taxanes and the vinca alkaloids. The results suggest that suppression of microtubule dynamics by erucin and the resulting impairment of critically important microtubule-dependent cell functions such as mitosis, cell migration and microtubule-based transport may be important in its cancer preventive activities.
Dynamics of Quantum Causal Structures
Castro-Ruiz, Esteban; Giacomini, Flaminia; Brukner, Časlav
2018-01-01
It was recently suggested that causal structures are both dynamical, because of general relativity, and indefinite, because of quantum theory. The process matrix formalism furnishes a framework for quantum mechanics on indefinite causal structures, where the order between operations of local laboratories is not definite (e.g., one cannot say whether operation in laboratory A occurs before or after operation in laboratory B ). Here, we develop a framework for "dynamics of causal structures," i.e., for transformations of process matrices into process matrices. We show that, under continuous and reversible transformations, the causal order between operations is always preserved. However, the causal order between a subset of operations can be changed under continuous yet nonreversible transformations. An explicit example is that of the quantum switch, where a party in the past affects the causal order of operations of future parties, leading to a transition from a channel from A to B , via superposition of causal orders, to a channel from B to A . We generalize our framework to construct a hierarchy of quantum maps based on transformations of process matrices and transformations thereof.
Dynamics of Quantum Causal Structures
Directory of Open Access Journals (Sweden)
Esteban Castro-Ruiz
2018-03-01
Full Text Available It was recently suggested that causal structures are both dynamical, because of general relativity, and indefinite, because of quantum theory. The process matrix formalism furnishes a framework for quantum mechanics on indefinite causal structures, where the order between operations of local laboratories is not definite (e.g., one cannot say whether operation in laboratory A occurs before or after operation in laboratory B. Here, we develop a framework for “dynamics of causal structures,” i.e., for transformations of process matrices into process matrices. We show that, under continuous and reversible transformations, the causal order between operations is always preserved. However, the causal order between a subset of operations can be changed under continuous yet nonreversible transformations. An explicit example is that of the quantum switch, where a party in the past affects the causal order of operations of future parties, leading to a transition from a channel from A to B, via superposition of causal orders, to a channel from B to A. We generalize our framework to construct a hierarchy of quantum maps based on transformations of process matrices and transformations thereof.
Structure and dynamics of solutions
Ohtaki, H
2013-01-01
Recent advances in the study of structural and dynamic properties of solutions have provided a molecular picture of solute-solvent interactions. Although the study of thermodynamic as well as electronic properties of solutions have played a role in the development of research on the rate and mechanism of chemical reactions, such macroscopic and microscopic properties are insufficient for a deeper understanding of fast chemical and biological reactions. In order to fill the gap between the two extremes, it is necessary to know how molecules are arranged in solution and how they change their pos
High cycle fatigue analysis of vortex suppression plate and secondary core support structures
International Nuclear Information System (INIS)
Xue Guohong; Li Yuan; Zhao Feiyun; Feng Shaodong; Yu Hao
2013-01-01
Background: Reactor internals are important equipment s in the reactor coolant system, its structure design needs high reliability in the entire lifetime, Reactor internals have occurred breakdown and the damage event due to flow induced vibrations in the domestic and foreign nuclear power plants, which make immediate influence on reactor safe operation and economic efficiency. Purpose: In this work, the dynamic response of reactor internals-vortex suppression plate and secondary core support structure (SCSS) under the loading from pump induced vibrations and flow induced vibrations are studied. Methods: Based on the finite element model of SCSS, Spectrum analysis and the harmonious analysis are performed, in order to get the response of the structure under flow induced vibrations. Then, the high fatigue of the structure is assessed according to the ASME B and PV Code. Results: The results indicate that alternate stresses of all the components satisfy the limiting value in the correlative requirements. Conclusions: The structure of SCSS could bear the vibration induced from the flow and the pump, and the method used in this article provides the reference for other reactor internals structure analysis like this. (authors)
Sierra Structural Dynamics Theory Manual
Energy Technology Data Exchange (ETDEWEB)
Reese, Garth M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2015-10-19
Sierra/SD provides a massively parallel implementation of structural dynamics finite element analysis, required for high fidelity, validated models used in modal, vibration, static and shock analysis of structural systems. This manual describes the theory behind many of the constructs in Sierra/SD. For a more detailed description of how to use Sierra/SD , we refer the reader to Sierra/SD, User's Notes . Many of the constructs in Sierra/SD are pulled directly from published material. Where possible, these materials are referenced herein. However, certain functions in Sierra/SD are specific to our implementation. We try to be far more complete in those areas. The theory manual was developed from several sources including general notes, a programmer notes manual, the user's notes and of course the material in the open literature. This page intentionally left blank.
Energy Technology Data Exchange (ETDEWEB)
Miletich, R.S.
1985-01-01
The effects of pergolide, a direct dopamine receptor agonist, on sleep and wakefulness, motor behavior and /sup 3/H-spiperone specific binding in limbic structures and striatum in rats was studied. The results show that pergolide induced a biphasic dose effect, with high doses increasing wakefulness and suppressing sleep while low dose decreased wakefulness, but increased sleep. It was shown that pergolide-induced sleep suppression was blocked by ..cap alpha..-glupenthixol and pimozide, two dopamine receptor antagonists. It was further shown that pergolide merely delayed the rebound resulting from rapid-eye-movement (REM) sleep deprivation, that dopamine receptors stimulation had no direct effect on the period, phase or amplitude of the circadian rhythm of REM sleep propensity and that there was no alteration in the coupling of REM sleep episodes with S/sub 2/ episodes. Rapid-eye-movement sleep deprivation resulted in increased sensitivity to the pergolide-induced wakefulness stimulation and sleep suppression and pergolide-induced motor behaviors of locomotion and head bobbing. /sup 3/H-spiperone specific binding to dopamine receptors was shown to be altered by REM sleep deprivation in the subcortical limbic structures. It is concluded that the REM sleep suppressing action of dopamine receptor stimulation is secondary to sleep suppression per se and not secondary to a unique effect on the REM sleep. Further, it is suggested that the wakefulness stimulating action of dopamine receptor agonists is mediated by activation of the dopamine receptors in the terminal areas of the mesolimbocortical dopamine projection system.
Suppression dampens unpleasant emotion faster than reappraisal: Neural dynamics in a Chinese sample.
Yuan, JiaJin; Long, QuanShan; Ding, NanXiang; Lou, YiXue; Liu, YingYing; Yang, JieMin
2015-05-01
The timing dynamics of regulating negative emotion with expressive suppression and cognitive reappraisal were investigated in a Chinese sample. Event-Related Potentials were recorded while subjects were required to view, suppress emotion expression to, or reappraise emotional pictures. The results showed a similar reduction in self-reported negative emotion during both strategies. Additionally, expressive suppression elicited larger amplitudes than reappraisal in central-frontal P3 component (340-480 ms). More importantly, the Late Positive Potential (LPP) amplitudes were decreased in each 200 ms of the 800-1600 ms time intervals during suppression vs. viewing conditions. In contrast, LPP amplitudes were similar for reappraisal and viewing conditions in all the time windows, except for the decreased amplitudes during reappraisal in the 1400-1600 ms. The LPP (but not P3) amplitudes were positively related to negative mood ratings, whereas the amplitudes of P3, rather than LPP, predict self-reported expressive suppression. These results suggest that expressive suppression decreases emotion responding more rapidly than reappraisal, at the cost of greater cognitive resource involvements in Chinese individuals.
Infrared suppression by hybrid EUV multilayer - IR lossy etalon structures
Medvedev, Viacheslav; Yakshin, Andrey; van de Kruijs, Robbert Wilhelmus Elisabeth; Krivtsun, V.M.; Yakunin, A.M.; Bijkerk, Frederik
2012-01-01
Many optical applications demand high reflectivity in a particular wavelength range and, simultaneously, suppression of radiation outside this prime range. Such parasitic radiation can lead to image distortions in imaging applications, or poor signal-noise ratios in spectroscopy. When working with
Jia, M.; Sun, Y.; Paz-Soldan, C.; Nazikian, R.; Gu, S.; Liu, Y. Q.; Abrams, T.; Bykov, I.; Cui, L.; Evans, T.; Garofalo, A.; Guo, W.; Gong, X.; Lasnier, C.; Logan, N. C.; Makowski, M.; Orlov, D.; Wang, H. H.
2018-05-01
Experiments using Resonant Magnetic Perturbations (RMPs), with a rotating n = 2 toroidal harmonic combined with a stationary n = 3 toroidal harmonic, have validated predictions that divertor heat and particle flux can be dynamically controlled while maintaining Edge Localized Mode (ELM) suppression in the DIII-D tokamak. Here, n is the toroidal mode number. ELM suppression over one full cycle of a rotating n = 2 RMP that was mixed with a static n = 3 RMP field has been achieved. Prominent heat flux splitting on the outer divertor has been observed during ELM suppression by RMPs in low collisionality regime in DIII-D. Strong changes in the three dimensional heat and particle flux footprint in the divertor were observed during the application of the mixed toroidal harmonic magnetic perturbations. These results agree well with modeling of the edge magnetic field structure using the TOP2D code, which takes into account the plasma response from the MARS-F code. These results expand the potential effectiveness of the RMP ELM suppression technique for the simultaneous control of divertor heat and particle load required in ITER.
Dynamic analysis of embedded structures
International Nuclear Information System (INIS)
Kausel, E.; Whitman, R.V.; Morray, J.P.
1977-01-01
The paper presents simplified rules to account for embeddment and soil layering in the soil-structure interaction problem, to be used in dynamic analysis. The relationship between the spring method, and a direct solution (in which both soil and structure are modeled with finite elements and linear members) is first presented. It is shown that for consistency of the results with the two solution methods the spring method should be performed in the following three steps: 1. Determination of the motion of the massless foundation (having the same shape as the actual one) when subjected to the same input motion as the direct solution. 2. Determination of the frequency dependent subgrade stiffness for the relevant degrees of freedom. 3. Computations of the response of the real structure supported on frequency dependent soil springs and subjected at the base of these springs to the motion computed in step 1. The first two steps require, in general, finite element methods, which would make the procedure not attractive. It is shown in the paper, however, that excellent approximations can be obtained, on the basis of 1-dimensional wave propagation theory for the solution of step 1, and correction factors modifying for embeddment the corresponding springs of a surface footing on a layered stratum, for the solution of step 2. (Auth.)
Dynamic buckling of inelastic structures
International Nuclear Information System (INIS)
Pegon, P.; Guelin, P.
1983-01-01
The aim of this paper is to provide research engineers with a method of approach, qualitative feature and order of magnitude of the relevant parameters in the field of dynamic buckling of structures exhibiting constitutive irreversibility and geometrical, constitutive or loading imperfections. It is difficult to adjust some of the classical analysis of the quasi-static elastic case. There remain also some difficulties in justifying the choice of constitutive schemes and in dealing with general kinematic formulation. Moreover, the interpretation of dynamical experimental data is not an easy matter. Consequently, the attempts described here use a simple symbolic model including all essential physical aspects. This symbolic model, of discrete character, is an n-hinged strut with masses located at each n+1 joint. The constitutive properties of the strut and hinge are defined using the same method: a dash-pot is in parallel with a two fold element (spring and friction-slider in series). The intrinsic restrictions are: the two dimensionality assumption, however no additional hypothesis are made concerning the kinematic of the constitutive elements; the use of simple sources of intrinsic dissipation. The relevant question of the longitudinal-transverse coupling effects is studied. Then, after various validation, we verify that a Lagrange resolution of this n+1 body problem gives physical relevant qualitative results concerning rods and cylindrical shells subjected to impact loading. (orig./RW)
Relating structure and dynamics in organisation models
Jonker, C.M.; Treur, J.
2003-01-01
To understand how an organisational structure relates to dynamics is an interesting fundamental challenge in the area of social modelling. Specifications of organisational structure usually have a diagrammatic form that abstracts from more detailed dynamics. Dynamic properties of agent systems, on
Chaotic Dynamics in Smart Grid and Suppression Scheme via Generalized Fuzzy Hyperbolic Model
Directory of Open Access Journals (Sweden)
Qiuye Sun
2014-01-01
Full Text Available This paper presents a method to control chaotic behavior of a typical Smart Grid based on generalized fuzzy hyperbolic model (GFHM. As more and more distributed generations (DG are incorporated into the Smart Grid, the chaotic behavior occurs increasingly. To verify the behavior, a dynamic model which describes a power system with DG is presented firstly. Then, the simulation result shows that the power system can lead to chaos under certain initial conditions. Based on the universal approximation of GFHM, we confirm that the chaotic behavior could be suppressed by a new controller, which is designed by means of solving a linear matrix inequality (LMI. This approach could make a good application to suppress the chaos in Smart Grid. Finally, a numerical example is given to demonstrate the effectiveness of the proposed chaotic suppression strategy.
Fluid-structure interaction in BWR suppression pool systems. Final report
International Nuclear Information System (INIS)
Nickell, R.E.
1979-09-01
The discharge of safety relief valves or a severe loss-of-coolant event in a boiling-water-cooled reactor steam supply system triggers a complex pressure suppression system that is based upon sub-surface steam condensation in large pools of water. The physical problems fall into two categories. The first is referred to as vent clearing and describes the process of expelling non-condensables from the system prior to steam flow. The second category covers a variety of phenomena related to the transient overexpansion of a condensable volume and the subsequent inertially-driven volume decrease. The dynamic loading of either event, depending upon fluid-structural design parameters, can be of concern in safety analysis. This report describes the development of a method for calculating the loads and the structural response for both types of problems. The method is embedded in a computer code, called PELE-IC, that couples a two-dimensional, incompressible eulerian fluid algorithm to a finite element shell algorithm. The fluid physics is based upon the SOLA algorithm, which provideds a trial velocity field using the Navier-Stokes equations that is subsequently corrected iteratively so that incompressibility, fluid-structure interface compatibility, and boundary conditions are satisfied. These fluid and fluid-structure algorithms have been extensively verified through calculations of known solutions from the classical literature, and by comparison to air and steam blowdown experiments
Langevin dynamics for ramified structures
Méndez, Vicenç; Iomin, Alexander; Horsthemke, Werner; Campos, Daniel
2017-06-01
We propose a generalized Langevin formalism to describe transport in combs and similar ramified structures. Our approach consists of a Langevin equation without drift for the motion along the backbone. The motion along the secondary branches may be described either by a Langevin equation or by other types of random processes. The mean square displacement (MSD) along the backbone characterizes the transport through the ramified structure. We derive a general analytical expression for this observable in terms of the probability distribution function of the motion along the secondary branches. We apply our result to various types of motion along the secondary branches of finite or infinite length, such as subdiffusion, superdiffusion, and Langevin dynamics with colored Gaussian noise and with non-Gaussian white noise. Monte Carlo simulations show excellent agreement with the analytical results. The MSD for the case of Gaussian noise is shown to be independent of the noise color. We conclude by generalizing our analytical expression for the MSD to the case where each secondary branch is n dimensional.
MSSM fine tuning problem and dynamical suppression of the Higgs mass parameters
International Nuclear Information System (INIS)
Kobayashi, Tatsuo; Terao, Haruhiko
2004-01-01
There have been several proposals for extension of the MSSM so as to ameliorate the fine tuning problem, which may be classified roughly into two categories; scenarios with enhanced quartic Higgs couplings and scenarios with radiatively stable Higgs soft masses. After a brief remark on some generic aspects of these approaches, we show a scenario with use of superconformal dynamics suppressing the Higgs mass parameters. (author)
MSSM fine tuning problem and dynamical suppression of the Higgs mass parameters
Energy Technology Data Exchange (ETDEWEB)
Kobayashi, Tatsuo [Kyoto Univ., Dept. of Physics, Kyoto (Japan); Terao, Haruhiko [Kanazawa Univ., Institute for Theoretical Physics, Kanazawa, Ishikawa (Japan)
2004-12-01
There have been several proposals for extension of the MSSM so as to ameliorate the fine tuning problem, which may be classified roughly into two categories; scenarios with enhanced quartic Higgs couplings and scenarios with radiatively stable Higgs soft masses. After a brief remark on some generic aspects of these approaches, we show a scenario with use of superconformal dynamics suppressing the Higgs mass parameters. (author)
Differentiation between benign and malignant breast lesions using fat-suppressed dynamic MR imaging
International Nuclear Information System (INIS)
Koshiishi, Takeshi; Isomoto, Ichirou; Nakamura, Kazukuni; Kajiwara, Yoshifumi; Izawa, Kunihide
1998-01-01
To assess the value and problems of fat-suppressed dynamic MR imaging in differentiating between benign and malignant lesions. In twenty-nine patients who underwent excisional biopsy or surgical resection, fat-suppressed dynamic MR imaging was performed with a 0.5 T superconducting magnet. Pre- and post-contrast 3D-spoiled gradient echo sequences were employed with fat suppression. We calculated and evaluated the contrast-to-noise ratio (CNR) and contrast enhancement ratio (CER) at each contrast determination time (CDT), which is the intermediate time in the scan. Time intensity curves of CNR showed no statistically significant difference between cancers and other benign lesions. The difference in CER between malignant and benign disease was highly significant (p=0.006) at CDT 45 sec., but there was great overlap in the time intensity curve of CER after CDT 45 sec. When we attempt to differentiate malignant from benign breast lesions by dynamic MR imaging, comparison of CNR is impertinent, and we should evaluate the differential diagnosis of cancer versus benign lesions by means of CER at CDT points of about 45 sec. (author)
Dynamic analysis and design of offshore structures
Chandrasekaran, Srinivasan
2015-01-01
This book attempts to provide readers with an overall idea of various types of offshore platform geometries. It covers the various environmental loads encountered by these structures, a detailed description of the fundamentals of structural dynamics in a class-room style, estimate of damping in offshore structures and their applications in the preliminary analysis and design. Basic concepts of structural dynamics are emphasized through simple illustrative examples and exercises. Design methodologies and guidelines, which are FORM based concepts are explained through a few applied example structures. Each chapter also has tutorials and exercises for self-learning. A dedicated chapter on stochastic dynamics will help the students to extend the basic concepts of structural dynamics to this advanced domain of research. Hydrodynamic response of offshore structures with perforated members is one of the recent research applications, which is found to be one of the effective manner of retrofitting offshore structur...
Structural and dynamical properties of Yukawa balls
International Nuclear Information System (INIS)
Block, D; Kroll, M; Arp, O; Piel, A; Kaeding, S; Ivanov, Y; Melzer, A; Henning, C; Baumgartner, H; Ludwig, P; Bonitz, M
2007-01-01
To study the structural and dynamical properties of finite 3D dust clouds (Yukawa balls) new diagnostic tools have been developed. This contribution describes the progress towards 3D diagnostics for measuring the particle positions. It is shown that these diagnostics are capable of investigating the structural and dynamical properties of Yukawa balls and gaining insight into their basic construction principles
Structural biology by NMR: structure, dynamics, and interactions.
Directory of Open Access Journals (Sweden)
Phineus R L Markwick
2008-09-01
Full Text Available The function of bio-macromolecules is determined by both their 3D structure and conformational dynamics. These molecules are inherently flexible systems displaying a broad range of dynamics on time-scales from picoseconds to seconds. Nuclear Magnetic Resonance (NMR spectroscopy has emerged as the method of choice for studying both protein structure and dynamics in solution. Typically, NMR experiments are sensitive both to structural features and to dynamics, and hence the measured data contain information on both. Despite major progress in both experimental approaches and computational methods, obtaining a consistent view of structure and dynamics from experimental NMR data remains a challenge. Molecular dynamics simulations have emerged as an indispensable tool in the analysis of NMR data.
International Nuclear Information System (INIS)
LeMaster, David M.
1997-01-01
A spin-diffusion-suppressed NOE buildup series has been measured for E. coli thioredoxin.The extensive 13C and 15N relaxation data previously reported for this protein allow for direct interpretation of dynamical contributions to the 1H-1H cross-relaxation rates for a large proportion of the NOE cross peaks. Estimates of the average accuracy for these derived NOE distances are bounded by 4% and 10%, based on a comparison to the corresponding X-ray distances. An independent fluctuation model is proposed for prediction of the dynamical corrections to 1H-1H cross-relaxation rates, based solely on experimental structural and heteronuclear relaxation data. This analysis is aided by the demonstration that heteronuclear order parameters greater than 0.6 depend only on the variance of the H-X bond orientation,independent of the motional model in either one- or two-dimensional diffusion (i.e., 1- S2 = 3/4 sin2 2 θσ). The combination of spin-diffusion-suppressed NOE data and analysis of dynamical corrections to 1H-1H cross-relaxation rates based on heteronuclear relaxation data has allowed for a detailed interpretation of various discrepancies between the reported solution and crystal structures
Combustion-Powered Actuation for Dynamic Stall Suppression - Simulations and Low-Mach Experiments
Matalanis, Claude G.; Min, Byung-Young; Bowles, Patrick O.; Jee, Solkeun; Wake, Brian E.; Crittenden, Tom; Woo, George; Glezer, Ari
2014-01-01
An investigation on dynamic-stall suppression capabilities of combustion-powered actuation (COMPACT) applied to a tabbed VR-12 airfoil is presented. In the first section, results from computational fluid dynamics (CFD) simulations carried out at Mach numbers from 0.3 to 0.5 are presented. Several geometric parameters are varied including the slot chordwise location and angle. Actuation pulse amplitude, frequency, and timing are also varied. The simulations suggest that cycle-averaged lift increases of approximately 4% and 8% with respect to the baseline airfoil are possible at Mach numbers of 0.4 and 0.3 for deep and near-deep dynamic-stall conditions. In the second section, static-stall results from low-speed wind-tunnel experiments are presented. Low-speed experiments and high-speed CFD suggest that slots oriented tangential to the airfoil surface produce stronger benefits than slots oriented normal to the chordline. Low-speed experiments confirm that chordwise slot locations suitable for Mach 0.3-0.4 stall suppression (based on CFD) will also be effective at lower Mach numbers.
Structural stability of nonlinear population dynamics.
Cenci, Simone; Saavedra, Serguei
2018-01-01
In population dynamics, the concept of structural stability has been used to quantify the tolerance of a system to environmental perturbations. Yet, measuring the structural stability of nonlinear dynamical systems remains a challenging task. Focusing on the classic Lotka-Volterra dynamics, because of the linearity of the functional response, it has been possible to measure the conditions compatible with a structurally stable system. However, the functional response of biological communities is not always well approximated by deterministic linear functions. Thus, it is unclear the extent to which this linear approach can be generalized to other population dynamics models. Here, we show that the same approach used to investigate the classic Lotka-Volterra dynamics, which is called the structural approach, can be applied to a much larger class of nonlinear models. This class covers a large number of nonlinear functional responses that have been intensively investigated both theoretically and experimentally. We also investigate the applicability of the structural approach to stochastic dynamical systems and we provide a measure of structural stability for finite populations. Overall, we show that the structural approach can provide reliable and tractable information about the qualitative behavior of many nonlinear dynamical systems.
Structural stability of nonlinear population dynamics
Cenci, Simone; Saavedra, Serguei
2018-01-01
In population dynamics, the concept of structural stability has been used to quantify the tolerance of a system to environmental perturbations. Yet, measuring the structural stability of nonlinear dynamical systems remains a challenging task. Focusing on the classic Lotka-Volterra dynamics, because of the linearity of the functional response, it has been possible to measure the conditions compatible with a structurally stable system. However, the functional response of biological communities is not always well approximated by deterministic linear functions. Thus, it is unclear the extent to which this linear approach can be generalized to other population dynamics models. Here, we show that the same approach used to investigate the classic Lotka-Volterra dynamics, which is called the structural approach, can be applied to a much larger class of nonlinear models. This class covers a large number of nonlinear functional responses that have been intensively investigated both theoretically and experimentally. We also investigate the applicability of the structural approach to stochastic dynamical systems and we provide a measure of structural stability for finite populations. Overall, we show that the structural approach can provide reliable and tractable information about the qualitative behavior of many nonlinear dynamical systems.
POSTER : Identifying dynamic data structures in Malware
Rupprecht, Thomas; Chen, Xi; White, David H.; Mühlberg, Jan Tobias; Bos, Herbert; Lüttgen, Gerald
2016-01-01
As the complexity of malware grows, so does the necessity of employing program structuring mechanisms during development. While control ow structuring is often obfuscated, the dynamic data structures employed by the program are typically untouched. We report on work in progress that exploits this
Fat-suppressed dynamic MR imaging for the postoperative evaluation of pituitary adenomas
International Nuclear Information System (INIS)
Akada, Kiyohiro
2000-01-01
The usefulness of the early post operative evaluation of pituitary adenomas with fat-suppressed MR imaging was studied. Thirty patients with pituitary adenoma, who underwent trans-sphenoidal surgery were analyzed. These include 22 with macroadenoma (3 recurrent cases) and 8 with microadenoma (2 recurrent cases). In all cases after adenoma resection, fat tissue was placed into the sella turcica to prevent postoperative cerebro-spinal fluid leakage and infections. T1-weighted and Gd DTPA-enhanced MR images were obtained using a 1.5-T superconductive MRI system (Shimadzu Co., Ltd.) by a standard technique and also by a fat suppression technique (chemical shift selective presaturation: CHESS) after surgery. It was difficult to discriminate between hematoma, fat tissue and pituitary posterior lobe on T1-weighted images within 1 month after surgery because of high-signal intensity. However, these regions could be distinguished one another by the CHESS technique. Normal pituitary anterior lobe could be identified in 86% of macroadenoma cases using Gd CHESS dynamic study, whereas it was identified only in 23% by standard technique. Normal anterior lobe was identified in 100% of microadenoma cases using Gd CHESS dynamic study. The residual tumors were found to invade into the supra sella or cavernous sinus, and these lesions could be distinguished from the surrounding tissue by the CHESS dynamic study in 83%, whereas only 33% could be distinguished by the standard technique. Although the fat tissue showed a time-sequence decrease in volume, high-signal intensity sometimes lasted long in association with degenerative granulation. In conclusion, CHESS dynamic MR Imaging study is useful for detection of the normal pituitary lobe and residual adenomas after trans-sphenoidal surgery. (author)
Dynamic analysis program for frame structure
International Nuclear Information System (INIS)
Ando, Kozo; Chiba, Toshio
1975-01-01
A general purpose computer program named ISTRAN/FD (Isub(HI) STRucture ANalysis/Frame structure, Dynamic analysis) has been developed for dynamic analysis of three-dimensional frame structures. This program has functions of free vibration analysis, seismic response analysis, graphic display by plotter and CRT, etc. This paper introduces ISTRAN/FD; examples of its application are shown with various problems : idealization of the cantilever, dynamic analysis of the main tower of the suspension bridge, three-dimensional vibration in the plate girder bridge, seismic response in the boiler steel structure, and dynamic properties of the underground LNG tank. In this last example, solid elements, in addition to beam elements, are especially used for the analysis. (auth.)
Structural Dynamic Behavior of Wind Turbines
Thresher, Robert W.; Mirandy, Louis P.; Carne, Thomas G.; Lobitz, Donald W.; James, George H. III
2009-01-01
The structural dynamicist s areas of responsibility require interaction with most other members of the wind turbine project team. These responsibilities are to predict structural loads and deflections that will occur over the lifetime of the machine, ensure favorable dynamic responses through appropriate design and operational procedures, evaluate potential design improvements for their impact on dynamic loads and stability, and correlate load and control test data with design predictions. Load prediction has been a major concern in wind turbine designs to date, and it is perhaps the single most important task faced by the structural dynamics engineer. However, even if we were able to predict all loads perfectly, this in itself would not lead to an economic system. Reduction of dynamic loads, not merely a "design to loads" policy, is required to achieve a cost-effective design. The two processes of load prediction and structural design are highly interactive: loads and deflections must be known before designers and stress analysts can perform structural sizing, which in turn influences the loads through changes in stiffness and mass. Structural design identifies "hot spots" (local areas of high stress) that would benefit most from dynamic load alleviation. Convergence of this cycle leads to a turbine structure that is neither under-designed (which may result in structural failure), nor over-designed (which will lead to excessive weight and cost).
Harmonic Suppressed Slot Antennas Using Rectangular/Circular Defected Ground Structures
Directory of Open Access Journals (Sweden)
Mohammad Saeid Ghaffarian
2012-01-01
Full Text Available Two wide rectangle-shaped microstrip-fed 2.6-GHz slot antennas using defected ground structures (DGSs with a low design complexity are proposed to achieve wideband harmonic suppression. To accomplish this, two rectangular DGSs (RDGSs in the first antenna and two circular DGSs (CDGSs in the second one with various dimensions are etched into the ground plane, which could have a wideband-stop characteristic. Simulated and measured reflection coefficients indicate that the two proposed structures effectively suppress the second and third harmonics up to 23 dB between 3.5 and 10.5 GHz with a maximum ripple of 2.4 dB. In addition, the radiation patterns and peak gains of the antennas can be suppressed at least 17 dB and 7.1 dBi, respectively, at the third harmonic frequency of 7.86 GHz.
Dynamics and acceleration in linear structures
International Nuclear Information System (INIS)
Le Duff, J.
1985-06-01
Basic methods of linear acceleration are reviewed. Both cases of non relativistic and ultra relativistic particles are considered. Induction linac, radiofrequency quadrupole are mentioned. Fundamental parameters of accelerating structures are recalled; they are transit time factor, shunt impedance, quality factor and stored energy, phase velocity and group velocity, filling time, space harmonics in loaded waveguides. Energy gain in linear accelerating structures is considered through standing wave structures and travelling wave structures. Then particle dynamics in linear accelerators is studied: longitudinal motion, transverse motion and dynamics in RFQ
Suppression of chaos at slow variables by rapidly mixing fast dynamics
Abramov, R.
2012-04-01
One of the key questions about chaotic multiscale systems is how the fast dynamics affects chaos at the slow variables, and, therefore, impacts uncertainty and predictability of the slow dynamics. Here we demonstrate that the linear slow-fast coupling with the total energy conservation property promotes the suppression of chaos at the slow variables through the rapid mixing at the fast variables, both theoretically and through numerical simulations. A suitable mathematical framework is developed, connecting the slow dynamics on the tangent subspaces to the infinite-time linear response of the mean state to a constant external forcing at the fast variables. Additionally, it is shown that the uncoupled dynamics for the slow variables may remain chaotic while the complete multiscale system loses chaos and becomes completely predictable at the slow variables through increasing chaos and turbulence at the fast variables. This result contradicts the common sense intuition, where, naturally, one would think that coupling a slow weakly chaotic system with another much faster and much stronger mixing system would result in general increase of chaos at the slow variables.
31st IMAC Conference on Structural Dynamics
Adams, Douglas; Carrella, Alex; Mayes, Randy; Rixen, Daniel; Allen, Matt; Cunha, Alvaro; Catbas, Fikret; Pakzad, Shamim; Racic, Vitomir; Pavic, Aleksandar; Reynolds, Paul; Simmermacher, Todd; Cogan, Scott; Moaveni, Babak; Papadimitriou, Costas; Allemang, Randall; Clerck, James; Niezrecki, Christopher; Wicks, Alfred
2013-01-01
Topics in Nonlinear Dynamics, Volume 1: Proceedings of the 31st IMAC, A Conference and Exposition on Structural Dynamics, 2013, the first volume of seven from the Conference, brings together contributions to this important area of research and engineering. The collection presents early findings and case studies on fundamental and applied aspects of Structural Dynamics, including papers on: Nonlinear Oscillations Nonlinearities In Practice Nonlinear System Identification: Methods Nonlinear System Identification: Friction & Contact Nonlinear Modal Analysis Nonlinear Modeling & Simulation Nonlinear Vibration Absorbers Constructive Utilization of Nonlinearity.
Network structure shapes spontaneous functional connectivity dynamics.
Shen, Kelly; Hutchison, R Matthew; Bezgin, Gleb; Everling, Stefan; McIntosh, Anthony R
2015-04-08
The structural organization of the brain constrains the range of interactions between different regions and shapes ongoing information processing. Therefore, it is expected that large-scale dynamic functional connectivity (FC) patterns, a surrogate measure of coordination between brain regions, will be closely tied to the fiber pathways that form the underlying structural network. Here, we empirically examined the influence of network structure on FC dynamics by comparing resting-state FC (rsFC) obtained using BOLD-fMRI in macaques (Macaca fascicularis) to structural connectivity derived from macaque axonal tract tracing studies. Consistent with predictions from simulation studies, the correspondence between rsFC and structural connectivity increased as the sample duration increased. Regions with reciprocal structural connections showed the most stable rsFC across time. The data suggest that the transient nature of FC is in part dependent on direct underlying structural connections, but also that dynamic coordination can occur via polysynaptic pathways. Temporal stability was found to be dependent on structural topology, with functional connections within the rich-club core exhibiting the greatest stability over time. We discuss these findings in light of highly variable functional hubs. The results further elucidate how large-scale dynamic functional coordination exists within a fixed structural architecture. Copyright © 2015 the authors 0270-6474/15/355579-10$15.00/0.
Dynamic response of structures with uncertain parameters
International Nuclear Information System (INIS)
Cai, Z H; Liu, Y; Yang, Y
2010-01-01
In this paper, an interval method for the dynamic response of structures with uncertain parameters is presented. In the presented method, the structural physical and geometric parameters and loads can be considered as interval variables. The structural stiffness matrix, mass matrix and loading vectors are described as the sum of two parts corresponding to the deterministic matrix and the uncertainty of the interval parameters. The interval problem is then transformed into approximate deterministic one. The Laplace transform is used to transform the equations of the dynamic system into linear algebra equations. The Maclaurin series expansion is applied on the modified dynamic equation in order to deal with the linear algebra equations. Numerical examples are studied by the presented interval method for the cases with and without damping. The upper bound and lower bound of the dynamic responses of the examples are compared, and it shows that the presented method is effective.
Design optimization applied in structural dynamics
Akcay-Perdahcioglu, Didem; de Boer, Andries; van der Hoogt, Peter; Tiskarna, T
2007-01-01
This paper introduces the design optimization strategies, especially for structures which have dynamic constraints. Design optimization involves first the modeling and then the optimization of the problem. Utilizing the Finite Element (FE) model of a structure directly in an optimization process
Dynamical structure of space and time
International Nuclear Information System (INIS)
Sannikov-Proskuryakov, S.S.
2000-01-01
A mathematically correct solution of the problem of ultraviolet divergences requires a radical change of our ideas on space and matter. We show that the space is a discontinuum in small which is the carrier of a new dynamical structure. Taking into account this structure, a new theory of elementary particles can be suggested
The Structure and Dynamics of GRB Jets
Energy Technology Data Exchange (ETDEWEB)
Granot, Jonathan; /KIPAC, Menlo Park
2006-10-25
There are several lines of evidence which suggest that the relativistic outflows in gamma-ray bursts (GRBs) are collimated into narrow jets. The jet structure has important implications for the true energy release and the event rate of GRBs, and can constrain the mechanism responsible for the acceleration and collimation of the jet. Nevertheless, the jet structure and its dynamics as it sweeps up the external medium and decelerates, are not well understood. In this review I discuss our current understanding of GRB jets, stressing their structure and dynamics.
Giant Suppression of the Activation Rate in Dynamical Systems Exhibiting Chaotic Transitions
Gac, J. M.; Xafebrowski, J. J.
2008-05-01
The phenomenon of giant suppression of activation, when two or more correlated noise signals act on the system, was found a few years ago in dynamical bistable or metastable systems. When the correlation between these noise signals is strong enough and the amplitudes of the noise are chosen correctly --- the life time of the metastable state may be longer than in the case of the application of only a single noise even by many orders of magnitude. In this paper, we investigate similar phenomena in systems exhibiting several chaotic transitions: Pomeau--Manneville intermittency, boundary crisis and interior crisis induced intermittency. Our goal is to show that, in these systems the application of two noise components with the proper choice of the parameters in the case of intermittency can also lengthen the mean laminar phase length or, in the case of boundary crisis, lengthen the time the trajectory spends on the pre-crisis attractor. In systems with crisis induced intermittency, we introduce a new phenomenon we called quasi-deterministic giant suppression of activation in which the lengthening of the laminar phase lengths is caused not by the action of two correlated noise signals but by a single noise term which is correlated with one of the chaotic variables of the system.
Modeling and identification in structural dynamics
Jayakumar, Paramsothy
1987-01-01
Analytical modeling of structures subjected to ground motions is an important aspect of fully dynamic earthquake-resistant design. In general, linear models are only sufficient to represent structural responses resulting from earthquake motions of small amplitudes. However, the response of structures during strong ground motions is highly nonlinear and hysteretic. System identification is an effective tool for developing analytical models from experimental data. Testing of full-scale prot...
Dynamic Response of a Floating Bridge Structure
Viuff, Thomas; Leira, Bernt Johan; Øiseth, Ole; Xiang, Xu
2016-01-01
A theoretical overview of the stochastic dynamic analysis of a floating bridge structure is presented. Emphasis is on the wave-induced response and the waves on the sea surface are idealized as a zero mean stationary Gaussian process. The first-order wave load processes are derived using linear potential theory and the structural idealization is based on the Finite Element Method. A frequency response calculation is presented for a simplified floating bridge structure example emphasising the ...
"Keep calm and carry on": structural correlates of expressive suppression of emotions.
Directory of Open Access Journals (Sweden)
Simone Kühn
Full Text Available There is a growing appreciation that individuals differ systematically in their use of particular emotion regulation strategies. Our aim was to examine the structural correlates of the habitual use of expressive suppression of emotions. Based on our previous research on the voluntary suppression of actions we expected this response-focused emotion regulation strategy to be associated with increased grey matter volume in the dorsomedial prefrontal cortex (dmPFC. On high-resolution MRI scans of 42 college-aged healthy adults we computed optimized voxel-based-morphometry (VBM to explore the correlation between grey matter volume and inter-individual differences in the tendency to suppress the expression of emotions assessed by means of the Emotion Regulation Questionnaire (Gross & John, 2003. We found a positive correlation between the habitual use of expressive suppression as an emotion regulation strategy and grey matter volume in the dmPFC. No other brain area showed a significant positive or negative correlation with the Emotion Regulation Questionnaire scores. The association between the suppression of expression of emotions and volume in the dmPFC supports the behavioural stability and biological foundation of the concept of this particular emotion regulation strategy within an age-homogenous sample of adults.
About the dynamics of structural phase transitions
International Nuclear Information System (INIS)
Medeiros, J.T.N.
1975-01-01
The dynamics of structural phase transitions with a fourth order interaction between the soft phonon fields is studied in the 1/n approximation, using many body methods at finite temperatures. Two limits are considered: high transition temperature T sub(c) (classical limit) and T sub(c) = 0 (quantum limit). The dynamical contribution to the critical coefficient eta of the correlation function is calculated in these limits. It is found that there is no dynamical contribution to eta in the classical limit, whereas in the quantum limit eta is non-zero only for dimensions of the system d [pt
Simultaneous determination of protein structure and dynamics
DEFF Research Database (Denmark)
Lindorff-Larsen, Kresten; Best, Robert B.; DePristo, M. A.
2005-01-01
at the atomic level about the structural and dynamical features of proteins-with the ability of molecular dynamics simulations to explore a wide range of protein conformations. We illustrate the method for human ubiquitin in solution and find that there is considerable conformational heterogeneity throughout......We present a protocol for the experimental determination of ensembles of protein conformations that represent simultaneously the native structure and its associated dynamics. The procedure combines the strengths of nuclear magnetic resonance spectroscopy-for obtaining experimental information...... the protein structure. The interior atoms of the protein are tightly packed in each individual conformation that contributes to the ensemble but their overall behaviour can be described as having a significant degree of liquid-like character. The protocol is completely general and should lead to significant...
Unifying dynamical and structural stability of equilibria
Arnoldi, Jean-François; Haegeman, Bart
2016-09-01
We exhibit a fundamental relationship between measures of dynamical and structural stability of linear dynamical systems-e.g. linearized models in the vicinity of equilibria. We show that dynamical stability, quantified via the response to external perturbations (i.e. perturbation of dynamical variables), coincides with the minimal internal perturbation (i.e. perturbations of interactions between variables) able to render the system unstable. First, by reformulating a result of control theory, we explain that harmonic external perturbations reflect the spectral sensitivity of the Jacobian matrix at the equilibrium, with respect to constant changes of its coefficients. However, for this equivalence to hold, imaginary changes of the Jacobian's coefficients have to be allowed. The connection with dynamical stability is thus lost for real dynamical systems. We show that this issue can be avoided, thus recovering the fundamental link between dynamical and structural stability, by considering stochastic noise as external and internal perturbations. More precisely, we demonstrate that a linear system's response to white-noise perturbations directly reflects the intensity of internal white-noise disturbance that it can accommodate before becoming stochastically unstable.
Structure and Dynamics of Negative Ions
International Nuclear Information System (INIS)
None
2000-01-01
This report describes progress made during the final three-year grant period 1997-2000. During this period, we experimentally investigated the structure and dynamics of negative ions by detaching the outermost electron in controlled processes induced by photon-, electron- and heavy particle-impact. In this manner we studied, at a fundamental level, the role of electron correlation in the structure and dynamics of simple, few-particle atomic systems. Our measurements have provided sensitive tests of the ability of theory to go beyond the independent electron model
Structural dynamics of electronic and photonic systems
Suhir, Ephraim; Steinberg, David S
2011-01-01
The proposed book will offer comprehensive and versatile methodologies and recommendations on how to determine dynamic characteristics of typical micro- and opto-electronic structural elements (printed circuit boards, solder joints, heavy devices, etc.) and how to design a viable and reliable structure that would be able to withstand high-level dynamic loading. Particular attention will be given to portable devices and systems designed for operation in harsh environments (such as automotive, aerospace, military, etc.) In-depth discussion from a mechanical engineer's viewpoint will be conducte
Chemical structure and dynamics: Annual report 1993
Energy Technology Data Exchange (ETDEWEB)
Colson, S.D.
1994-07-01
The Chemical Structure and Dynamics program responds to the need for a fundamental, molecular-level understanding of chemistry at the wide variety of environmentally-important interfaces. The research program is built around the established relationship between structure, thermodynamics, and kinetics. This research effort continues to evolve into a program of rigorous studies of fundamental molecular processes in model systems (e.g., well-characterized surfaces, single-component solutions, clusters, and biological molecules), and studies of complex systems found in the environment. Experimental studies of molecular and supramolecular structures and thermodynamics are key to understanding the nature of matter, and lead to direct comparison with computational results. Kinetic and mechanistic measurements, combined with real-time dynamics measurements of atomic and molecular motions during chemical reactions, provide for a molecular-level description of chemical reactions. The anticipated results of this work are the achievement of a quantitative understanding of chemical processes at complex interfaces, the development of new techniques for the detection and measurement of species at such interfaces, and the interpretation and extrapolation of the observations in terms of models of interfacial chemistry. The Chemical Structure and Dynamics research program includes five areas described in detail in this report: Reaction mechanisms at solid interfaces; Solution and solution interfaces; Structure and dynamics of biological systems; Analytical methods development; and atmospheric chemistry. Extended abstracts are presented for 23 studies.
Multiscale structure in eco-evolutionary dynamics
Stacey, Blake C.
In a complex system, the individual components are neither so tightly coupled or correlated that they can all be treated as a single unit, nor so uncorrelated that they can be approximated as independent entities. Instead, patterns of interdependency lead to structure at multiple scales of organization. Evolution excels at producing such complex structures. In turn, the existence of these complex interrelationships within a biological system affects the evolutionary dynamics of that system. I present a mathematical formalism for multiscale structure, grounded in information theory, which makes these intuitions quantitative, and I show how dynamics defined in terms of population genetics or evolutionary game theory can lead to multiscale organization. For complex systems, "more is different," and I address this from several perspectives. Spatial host--consumer models demonstrate the importance of the structures which can arise due to dynamical pattern formation. Evolutionary game theory reveals the novel effects which can result from multiplayer games, nonlinear payoffs and ecological stochasticity. Replicator dynamics in an environment with mesoscale structure relates to generalized conditionalization rules in probability theory. The idea of natural selection "acting at multiple levels" has been mathematized in a variety of ways, not all of which are equivalent. We will face down the confusion, using the experience developed over the course of this thesis to clarify the situation.
Dynamical decoupling sequences for multi-qubit dephasing suppression and long-time quantum memory
International Nuclear Information System (INIS)
Paz-Silva, Gerardo A; Lee, Seung-Woo; Green, Todd J; Viola, Lorenza
2016-01-01
We consider a class of multi-qubit dephasing models that combine classical noise sources and linear coupling to a bosonic environment, and are controlled by arbitrary sequences of dynamical decoupling pulses. Building on a general transfer filter-function framework for open-loop control, we provide an exact representation of the controlled dynamics for arbitrary stationary non-Gaussian classical and quantum noise statistics, with analytical expressions emerging when all dephasing sources are Gaussian. This exact characterization is used to establish two main results. First, we construct multi-qubit sequences that ensure maximum high-order error suppression in both the time and frequency domain and that can be exponentially more efficient than existing ones in terms of total pulse number. Next, we show how long-time multi-qubit storage may be achieved by meeting appropriate conditions for the emergence of a fidelity plateau under sequence repetition, thereby generalizing recent results for single-qubit memory under Gaussian dephasing. In both scenarios, the key step is to endow multi-qubit sequences with a suitable displacement anti-symmetry property, which is of independent interest for applications ranging from environment-assisted entanglement generation to multi-qubit noise spectroscopy protocols. (paper)
Koval, Peter; Butler, Emily A; Hollenstein, Tom; Lanteigne, Dianna; Kuppens, Peter
2015-01-01
The tendency for emotions to be predictable over time, labelled emotional inertia, has been linked to low well-being and is thought to reflect impaired emotion regulation. However, almost no studies have examined how emotion regulation relates to emotional inertia. We examined the effects of cognitive reappraisal and expressive suppression on the inertia of behavioural, subjective and physiological measures of emotion. In Study 1 (N = 111), trait suppression was associated with higher inertia of negative behaviours. We replicated this finding experimentally in Study 2 (N = 186). Furthermore, in Study 2, instructed suppressors and reappraisers both showed higher inertia of positive behaviours, and reappraisers displayed higher inertia of heart rate. Neither suppression nor reappraisal were associated with the inertia of subjective feelings in either study. Thus, the effects of suppression and reappraisal on the temporal dynamics of emotions depend on the valence and emotional response component in question.
Barnes, Rachel D.; Sawaoka, Takuya; White, Marney A.; Masheb, Robin M.; Grilo, Carlos M.
2013-01-01
Prior research on the relations among eating behaviors and thought suppression is limited to a measure of general thought suppression, the White Bear Suppression Inventory. To address this limitation, researchers recently validated the Food Thought Suppression Inventory (FTSI). Analyses using this measure suggest that food thought suppression is distinct from and is more predictive of eating disorder psychopathology than is general thought suppression. The FTSI, however, has not yet been validated in clinical samples. The purpose of the current study is to examine the factor structure and clinical correlates of the FTSI within treatment seeking obese women with binge eating disorder (BED; N = 128). Analyses revealed a valid and reliable one-factor measure of food thought suppression that was related to higher levels of eating and general psychopathology. The findings provide evidence for the use of the FTSI with obese women with BED. Future research should examine the psychometric properties of the FTSI within larger and more diverse samples. PMID:23265399
Dynamic telomerase gene suppression via network effects of GSK3 inhibition.
Directory of Open Access Journals (Sweden)
Alan E Bilsland
2009-07-01
Full Text Available Telomerase controls telomere homeostasis and cell immortality and is a promising anti-cancer target, but few small molecule telomerase inhibitors have been developed. Reactivated transcription of the catalytic subunit hTERT in cancer cells controls telomerase expression. Better understanding of upstream pathways is critical for effective anti-telomerase therapeutics and may reveal new targets to inhibit hTERT expression.In a focused promoter screen, several GSK3 inhibitors suppressed hTERT reporter activity. GSK3 inhibition using 6-bromoindirubin-3'-oxime suppressed hTERT expression, telomerase activity and telomere length in several cancer cell lines and growth and hTERT expression in ovarian cancer xenografts. Microarray analysis, network modelling and oligonucleotide binding assays suggested that multiple transcription factors were affected. Extensive remodelling involving Sp1, STAT3, c-Myc, NFkappaB, and p53 occurred at the endogenous hTERT promoter. RNAi screening of the hTERT promoter revealed multiple kinase genes which affect the hTERT promoter, potentially acting through these factors. Prolonged inhibitor treatments caused dynamic expression both of hTERT and of c-Jun, p53, STAT3, AR and c-Myc.Our results indicate that GSK3 activates hTERT expression in cancer cells and contributes to telomere length homeostasis. GSK3 inhibition is a clinical strategy for several chronic diseases. These results imply that it may also be useful in cancer therapy. However, the complex network effects we show here have implications for either setting.
Structure and dynamics of the solar chromosphere
Krijger, Johannes Mattheus
2002-01-01
The thesis "Structure and dynamics of the solar chromosphere" of J.M. Krijger is a study on the behavior of the solar chromosphere, the thin layer just above the solar surface (photosphere) visible in purple red light during a total solar eclipse. The most important result of this thesis is that the
Natural Poisson structures of nonlinear plasma dynamics
International Nuclear Information System (INIS)
Kaufman, A.N.
1982-01-01
Hamiltonian field theories, for models of nonlinear plasma dynamics, require a Poisson bracket structure for functionals of the field variables. These are presented, applied, and derived for several sets of field variables: coherent waves, incoherent waves, particle distributions, and multifluid electrodynamics. Parametric coupling of waves and plasma yields concise expressions for ponderomotive effects (in kinetic and fluid models) and for induced scattering. (Auth.)
Natural Poisson structures of nonlinear plasma dynamics
International Nuclear Information System (INIS)
Kaufman, A.N.
1982-06-01
Hamiltonian field theories, for models of nonlinear plasma dynamics, require a Poisson bracket structure for functionals of the field variables. These are presented, applied, and derived for several sets of field variables: coherent waves, incoherent waves, particle distributions, and multifluid electrodynamics. Parametric coupling of waves and plasma yields concise expressions for ponderomotive effects (in kinetic and fluid models) and for induced scattering
Structural dynamic modification using additive damping
Indian Academy of Sciences (India)
elements, FEM and perturbation methods for reanalysis or structural dynamic modification ... to a system changes its mass, stiffness and damping. Thus ... due to the phase difference between stress ' and strain or 'a И E1 З iE2 for direct strain.
Proteins with Novel Structure, Function and Dynamics
Pohorille, Andrew
2014-01-01
Recently, a small enzyme that ligates two RNA fragments with the rate of 10(exp 6) above background was evolved in vitro (Seelig and Szostak, Nature 448:828-831, 2007). This enzyme does not resemble any contemporary protein (Chao et al., Nature Chem. Biol. 9:81-83, 2013). It consists of a dynamic, catalytic loop, a small, rigid core containing two zinc ions coordinated by neighboring amino acids, and two highly flexible tails that might be unimportant for protein function. In contrast to other proteins, this enzyme does not contain ordered secondary structure elements, such as alpha-helix or beta-sheet. The loop is kept together by just two interactions of a charged residue and a histidine with a zinc ion, which they coordinate on the opposite side of the loop. Such structure appears to be very fragile. Surprisingly, computer simulations indicate otherwise. As the coordinating, charged residue is mutated to alanine, another, nearby charged residue takes its place, thus keeping the structure nearly intact. If this residue is also substituted by alanine a salt bridge involving two other, charged residues on the opposite sides of the loop keeps the loop in place. These adjustments are facilitated by high flexibility of the protein. Computational predictions have been confirmed experimentally, as both mutants retain full activity and overall structure. These results challenge our notions about what is required for protein activity and about the relationship between protein dynamics, stability and robustness. We hypothesize that small, highly dynamic proteins could be both active and fault tolerant in ways that many other proteins are not, i.e. they can adjust to retain their structure and activity even if subjected to mutations in structurally critical regions. This opens the doors for designing proteins with novel functions, structures and dynamics that have not been yet considered.
Structural test and analysis of a model of a BWR suppression chamber support in the plastic regime
International Nuclear Information System (INIS)
Blumer, U.R.; Klaeui, E.; Bosshard, E.P.
1991-01-01
A BWR Mark I suppression pool support has been analysed and tested in the laboratory. The aim was the demonstration of the acceptability of hypothetical dynamic loadings resulting from simultaneous steam blowdown through all safety relief valves. The analysis has shown that plastic deformation will locally occur, which is difficult to assess purely theoretical. Therefore tests in reduced scale were performed that show the amount and distribution of plastic flow in the supports. The paper describes the elastic analysis, the theory of the scaling laws for the reduced scale test, the test and its results. It also shows the thermographical method that has been used to determine the plastic material flow in the support structure. (author)
Component mode synthesis in structural dynamics
International Nuclear Information System (INIS)
Reddy, G.R.; Vaze, K.K.; Kushwaha, H.S.
1993-01-01
In seismic analysis of Nuclear Reactor Structures and equipments eigen solution requires large computer time. Component mode synthesis is an efficient technique with which one can evaluate dynamic characteristics of a large structure with minimum computer time. Due to this reason it is possible to do a coupled analysis of structure and equipment which takes into account the interaction effects. Basically in this the method large size structure is divided into small substructures and dynamic characteristics of individual substructure are determined. The dynamic characteristics of entire structure are evaluated by synthesising the individual substructure characteristics. Component mode synthesis has been applied in this paper to the analysis of a tall heavy water upgrading tower. Use of fixed interface normal modes, constrained modes, attachment modes in the component mode synthesis using energy principle and using Ritz vectors have been discussed. The validity of this method is established by solving fixed-fixed beam and comparing the results obtained by conventional and classical method. The eigen value problem has been solved using simultaneous iteration method. (author)
The dynamical conductance of graphene tunnelling structures
International Nuclear Information System (INIS)
Zhang Huan; Chan, K S; Lin Zijing
2011-01-01
The dynamical conductances of graphene tunnelling structures were numerically calculated using the scattering matrix method with the interaction effect included in a phenomenological approach. The overall single-barrier dynamical conductance is capacitative. Transmission resonances in the single-barrier structure lead to dips in the capacitative imaginary part of the response. This is different from the ac responses of typical semiconductor nanostructures, where transmission resonances usually lead to inductive peaks. The features of the dips depend on the Fermi energy. When the Fermi energy is below half of the barrier height, the dips are sharper. When the Fermi energy is higher than half of the barrier height, the dips are broader. Inductive behaviours can be observed in a double-barrier structure due to the resonances formed by reflection between the two barriers.
The dynamical conductance of graphene tunnelling structures.
Zhang, Huan; Chan, K S; Lin, Zijing
2011-12-16
The dynamical conductances of graphene tunnelling structures were numerically calculated using the scattering matrix method with the interaction effect included in a phenomenological approach. The overall single-barrier dynamical conductance is capacitative. Transmission resonances in the single-barrier structure lead to dips in the capacitative imaginary part of the response. This is different from the ac responses of typical semiconductor nanostructures, where transmission resonances usually lead to inductive peaks. The features of the dips depend on the Fermi energy. When the Fermi energy is below half of the barrier height, the dips are sharper. When the Fermi energy is higher than half of the barrier height, the dips are broader. Inductive behaviours can be observed in a double-barrier structure due to the resonances formed by reflection between the two barriers.
Dynamic structural disorder in supported nanoscale catalysts
International Nuclear Information System (INIS)
Rehr, J. J.; Vila, F. D.
2014-01-01
We investigate the origin and physical effects of “dynamic structural disorder” (DSD) in supported nano-scale catalysts. DSD refers to the intrinsic fluctuating, inhomogeneous structure of such nano-scale systems. In contrast to bulk materials, nano-scale systems exhibit substantial fluctuations in structure, charge, temperature, and other quantities, as well as large surface effects. The DSD is driven largely by the stochastic librational motion of the center of mass and fluxional bonding at the nanoparticle surface due to thermal coupling with the substrate. Our approach for calculating and understanding DSD is based on a combination of real-time density functional theory/molecular dynamics simulations, transient coupled-oscillator models, and statistical mechanics. This approach treats thermal and dynamic effects over multiple time-scales, and includes bond-stretching and -bending vibrations, and transient tethering to the substrate at longer ps time-scales. Potential effects on the catalytic properties of these clusters are briefly explored. Model calculations of molecule-cluster interactions and molecular dissociation reaction paths are presented in which the reactant molecules are adsorbed on the surface of dynamically sampled clusters. This model suggests that DSD can affect both the prefactors and distribution of energy barriers in reaction rates, and thus can significantly affect catalytic activity at the nano-scale
Dynamic structural disorder in supported nanoscale catalysts
Energy Technology Data Exchange (ETDEWEB)
Rehr, J. J.; Vila, F. D. [Department of Physics, University of Washington, Seattle, Washington 98195 (United States)
2014-04-07
We investigate the origin and physical effects of “dynamic structural disorder” (DSD) in supported nano-scale catalysts. DSD refers to the intrinsic fluctuating, inhomogeneous structure of such nano-scale systems. In contrast to bulk materials, nano-scale systems exhibit substantial fluctuations in structure, charge, temperature, and other quantities, as well as large surface effects. The DSD is driven largely by the stochastic librational motion of the center of mass and fluxional bonding at the nanoparticle surface due to thermal coupling with the substrate. Our approach for calculating and understanding DSD is based on a combination of real-time density functional theory/molecular dynamics simulations, transient coupled-oscillator models, and statistical mechanics. This approach treats thermal and dynamic effects over multiple time-scales, and includes bond-stretching and -bending vibrations, and transient tethering to the substrate at longer ps time-scales. Potential effects on the catalytic properties of these clusters are briefly explored. Model calculations of molecule-cluster interactions and molecular dissociation reaction paths are presented in which the reactant molecules are adsorbed on the surface of dynamically sampled clusters. This model suggests that DSD can affect both the prefactors and distribution of energy barriers in reaction rates, and thus can significantly affect catalytic activity at the nano-scale.
Wang, Zhen; Zheng, Yi; Mao, Yu-feng; Wang, Ya-zhou; Yu, Yan-ting; Liu, Hong-ning
2018-03-01
In the disturbance of unsteady flow field under the sea, the monitoring accuracy and precision of the bottom-mounted acoustic monitoring platform will decrease. In order to reduce the hydrodynamic interference, the platform wrapped with fairing structure and separated from the retrieval unit is described. The suppression effect evaluation based on the correlation theory of sound pressure and particle velocity for spherical wave in infinite homogeneous medium is proposed and the difference value between them is used to evaluate the hydrodynamic restraining performance of the bottom-mounted platform under far field condition. Through the sea test, it is indicated that the platform with sparse layers fairing structure (there are two layers for the fairing, in which the inside layer is 6-layers sparse metal net, and the outside layer is 1-layer polyester cloth, and then it takes sparse layers for short) has no attenuation in the sound pressure response to the sound source signal, but obvious suppression in the velocity response to the hydrodynamic noise. The effective frequency of the fairing structure is decreased below 10 Hz, and the noise magnitude is reduced by 10 dB. With the comparison of different fairing structures, it is concluded that the tighter fairing structure can enhance the performance of sound transmission and flow restraining.
Coupled problems in transient fluid and structural dynamics in nuclear engineering
International Nuclear Information System (INIS)
Krieg, R.
1978-01-01
Some important problems in coupled fluid-structural dynamics which occur in safety investigations of liquid metal fast breeder reactors (LMFBR). light water reactors and nuclear reprocessing plants are discussed and a classification of solution methods is introduced. A distinction is made between the step by step solution procedure, where available computer codes in fluid and structural dynamics are coupled, and advanced simultaneous solution methods, where the coupling is carried out at the level of the fundamental equations. Results presented include the transient deformation of a two-row pin bundle surrounded by an infinite fluid field, vapour explosions in a fluid container and containment distortions due to bubble collapse in the pressure suppression system of a boiling water reactor. A recently developed simultaneous solution method is presented in detail. Here the fluid dynamics (inviscid, incompressible fluid) is described by a singularity method which reduces the three-dimensional fluid dynamics problems to a two-dimensional formulation. In this way the three-dynamics fluid dynamics as well as the structural (shell) dynamics can be described essentially by common unknowns at the fluid-structural interface. The resulting equations for the coupled fluid-structural dynamics are analogous to to the equations of motion of the structural dynamics alone. (author)
Dynamics and structure of stretched flames
Energy Technology Data Exchange (ETDEWEB)
Law, C.K. [Princeton Univ., NJ (United States)
1993-12-01
This program aims to gain fundamental understanding on the structure, geometry, and dynamics of laminar premixed flames, and relate these understanding to the practical issues of flame extinction and stabilization. The underlying fundamental interest here is the recent recognition that the response of premixed flames can be profoundly affected by flame stretch, as manifested by flow nonuniformity, flame curvature, and flame/flow unsteadiness. As such, many of the existing understanding on the behavior of premixed flames need to be qualitatively revised. The research program consists of three major thrusts: (1) detailed experimental and computational mapping of the structure of aerodynamically-strained planar flames, with emphasis on the effects of heat loss, nonequidiffusion, and finite residence time on the flame thickness, extent of incomplete reaction, and the state of extinction. (2) Analytical study of the geometry and dynamics of stretch-affected wrinkled flame sheets in simple configurations, as exemplified by the Bunsen flame and the spatially-periodic flame, with emphasis on the effects of nonlinear stretch, the phenomena of flame cusping, smoothing, and tip opening, and their implications on the structure and burning rate of turbulent flames. (3) Stabilization and blowoff of two-dimensional inverted premixed and stabilization and determining the criteria governing flame blowoff. The research is synergistically conducted through the use of laser-based diagnostics, computational simulation of the flame structure with detailed chemistry and transport, and mathematical analysis of the flame dynamics.
Chemical structure and dynamics. Annual report 1995
Energy Technology Data Exchange (ETDEWEB)
Colson, S.D.; McDowell, R.S.
1996-05-01
The Chemical Structure and Dynamics program is a major component of Pacific Northwest National Laboratory`s Environmental Molecular Sciences Laboratory (EMSL), providing a state-of-the-art collaborative facility for studies of chemical structure and dynamics. We respond to the need for a fundamental, molecular-level understanding of chemistry at a wide variety of environmentally important interfaces by (1) extending the experimental characterization and theoretical description of chemical reactions to encompass the effects of condensed media and interfaces; (2) developing a multidisciplinary capability for describing interfacial chemical processes within which the new knowledge generated can be brought to bear on complex phenomena in environmental chemistry and in nuclear waste processing and storage; and (3) developing state-of-the-art analytical methods for the characterization of waste tanks and pollutant distributions, and for detection and monitoring of trace atmospheric species.
Chemical structure and dynamics: Annual report 1996
International Nuclear Information System (INIS)
Colson, S.D.; McDowell, R.S.
1997-03-01
The Chemical Structure and Dynamics (CS ampersand D) program is a major component of the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL) developed by Pacific Northwest National Laboratory (PNNL) to provide a state-of-the-art collaborative facility for studies of chemical structure and dynamics. We respond to the need for a fundamental, molecular-level understanding of chemistry at a wide variety of environmentally important interfaces by (1) extending the experimental characterization and theoretical description of chemical reactions to encompass the effects of condensed media and interfaces; (2) developing a multidisciplinary capability for describing interfacial chemical processes within which the new knowledge generated can be brought to bear on complex phenomena in environmental chemistry and in nuclear waste processing and storage; and (3) developing state-of-the-art analytical methods for characterizing waste tanks and pollutant distributions, and for detecting and monitoring trace atmospheric species
Annual Report 2000. Chemical Structure and Dynamics
Energy Technology Data Exchange (ETDEWEB)
Colson, Steven D.; McDowell, Robin S.
2001-04-15
This annual report describes the research and accomplishments of the Chemical Structure and Dynamics Program in the year 2000, one of six research programs at the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL) - a multidisciplinary, national scientific user facility and research organization. The Chemical Structure and Dynamics (CS&D) program is meeting the need for a fundamental, molecular-level understanding by 1) extending the experimental characterization and theoretical description of chemical reactions to encompass the effects of condensed media and interfaces; 2) developing a multidisciplinary capability for describing interfacial chemical processes relevant to environmental chemistry; and 3) developing state-of-the-art research and analytical methods for characterizing complex materials of the types found in natural and contaminated systems.
Chemical structure and dynamics: Annual report 1996
Energy Technology Data Exchange (ETDEWEB)
Colson, S.D.; McDowell, R.S.
1997-03-01
The Chemical Structure and Dynamics (CS&D) program is a major component of the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL) developed by Pacific Northwest National Laboratory (PNNL) to provide a state-of-the-art collaborative facility for studies of chemical structure and dynamics. We respond to the need for a fundamental, molecular-level understanding of chemistry at a wide variety of environmentally important interfaces by (1) extending the experimental characterization and theoretical description of chemical reactions to encompass the effects of condensed media and interfaces; (2) developing a multidisciplinary capability for describing interfacial chemical processes within which the new knowledge generated can be brought to bear on complex phenomena in environmental chemistry and in nuclear waste processing and storage; and (3) developing state-of-the-art analytical methods for characterizing waste tanks and pollutant distributions, and for detecting and monitoring trace atmospheric species.
On R factors for dynamic structure crystallography
DEFF Research Database (Denmark)
Coppens, Philip; Kaminski, Radoslaw; Schmøkel, Mette Stokkebro
2010-01-01
In studies of dynamic changes in crystals in which induced metastable species may have lifetimes of microseconds or less, refinements are most sensitive if based on the changes induced in the measured intensities. Agreement factors appropriate for such refinements, based on the ratios of the inte...... of the intensities before and after the external perturbation is applied, are discussed and compared with R factors commonly applied in static structure crystallography....
Feature Extraction for Structural Dynamics Model Validation
Energy Technology Data Exchange (ETDEWEB)
Farrar, Charles [Los Alamos National Laboratory; Nishio, Mayuko [Yokohama University; Hemez, Francois [Los Alamos National Laboratory; Stull, Chris [Los Alamos National Laboratory; Park, Gyuhae [Chonnam Univesity; Cornwell, Phil [Rose-Hulman Institute of Technology; Figueiredo, Eloi [Universidade Lusófona; Luscher, D. J. [Los Alamos National Laboratory; Worden, Keith [University of Sheffield
2016-01-13
As structural dynamics becomes increasingly non-modal, stochastic and nonlinear, finite element model-updating technology must adopt the broader notions of model validation and uncertainty quantification. For example, particular re-sampling procedures must be implemented to propagate uncertainty through a forward calculation, and non-modal features must be defined to analyze nonlinear data sets. The latter topic is the focus of this report, but first, some more general comments regarding the concept of model validation will be discussed.
Handbook on dynamics of jointed structures.
Energy Technology Data Exchange (ETDEWEB)
Ames, Nicoli M.; Lauffer, James P.; Jew, Michael D.; Segalman, Daniel Joseph; Gregory, Danny Lynn; Starr, Michael James; Resor, Brian Ray
2009-07-01
The problem of understanding and modeling the complicated physics underlying the action and response of the interfaces in typical structures under dynamic loading conditions has occupied researchers for many decades. This handbook presents an integrated approach to the goal of dynamic modeling of typical jointed structures, beginning with a mathematical assessment of experimental or simulation data, development of constitutive models to account for load histories to deformation, establishment of kinematic models coupling to the continuum models, and application of finite element analysis leading to dynamic structural simulation. In addition, formulations are discussed to mitigate the very short simulation time steps that appear to be required in numerical simulation for problems such as this. This handbook satisfies the commitment to DOE that Sandia will develop the technical content and write a Joints Handbook. The content will include: (1) Methods for characterizing the nonlinear stiffness and energy dissipation for typical joints used in mechanical systems and components. (2) The methodology will include practical guidance on experiments, and reduced order models that can be used to characterize joint behavior. (3) Examples for typical bolted and screw joints will be provided.
Structural dynamic analysis of turbine blade
Antony, A. Daniel; Gopalsamy, M.; Viswanadh, Chaparala B. V.; Krishnaraj, R.
2017-10-01
In any gas turbine design cycle, blade design is a crucial element which needs maximum attention to meet the aerodynamic performance, structural safety margins, manufacturing feasibility, material availability etc. In present day gas turbine engines, most of the failures occur during engine development test and in-service, in rotor and stator blades due to fatigue and resonance failures. To address this issue, an extensive structural dynamic analysis is carried out to predict the natural frequencies and mode shapes using FE methods. Using the dynamics characteristics, the Campbell diagram is constructed to study the possibility of resonance at various operating speeds. In this work, the feasibility of using composite material in place of titanium alloy from the structural dynamics point of view. This is being attempted in a Low-pressure compressor where the temperatures are relatively low and fixed with the casings. The analysis will be carried out using FE method for different composite material with different lamina orientations chosen through the survey. This study will focus on the sensitivity of blade mode shapes to different laminae orientations, which will be used to alter the natural frequency and tailor the mode shapes. Campbell diagrams of existing titanium alloy are compared with the composite materials with different laminae at all critical operating conditions. The existing manufacturing methods and the proven techniques for blade profiles will also be discussed in this report.
DYNAMIC CINEMATIC TO A STRUCTURE 2R
Directory of Open Access Journals (Sweden)
Florian Ion Tiberiu Petrescu
2016-06-01
Full Text Available Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 Flat structures 2R can solve all the problems posed by all the robotic anthropomorphic structures. The study of the anthropomorphic robots by the use of a flat structure 2R is a much easier method than classical used spatial methods. The paper outlines a method for the determination of dynamic to a robotic structure 2R balanced. 2R plane structures are used in practice only in the form balanced, for which in this paper will be made, initial, the total balance, and then the study cinematico-dynamic will only develop on the model already balanced. Dynamic relations presented then briefly without deduction will be explained and discussed with regard to their application. On the basis of the model presented and following calculations performed can be chosen correctly the two electric motors in the actuator. /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}
Evers, Jochem B; Bastiaans, Lammert
2016-05-01
Suppression of weed growth in a crop canopy can be enhanced by improving crop competitiveness. One way to achieve this is by modifying the crop planting pattern. In this study, we addressed the question to what extent a uniform planting pattern increases the ability of a crop to compete with weed plants for light compared to a random and a row planting pattern, and how this ability relates to crop and weed plant density as well as the relative time of emergence of the weed. To this end, we adopted the functional-structural plant modelling approach which allowed us to explicitly include the 3D spatial configuration of the crop-weed canopy and to simulate intra- and interspecific competition between individual plants for light. Based on results of simulated leaf area development, canopy photosynthesis and biomass growth of the crop, we conclude that differences between planting pattern were small, particularly if compared to the effects of relative time of emergence of the weed, weed density and crop density. Nevertheless, analysis of simulated weed biomass demonstrated that a uniform planting of the crop improved the weed-suppression ability of the crop canopy. Differences in weed suppressiveness between planting patterns were largest with weed emergence before crop emergence, when the suppressive effect of the crop was only marginal. With simultaneous emergence a uniform planting pattern was 8 and 15 % more competitive than a row and a random planting pattern, respectively. When weed emergence occurred after crop emergence, differences between crop planting patterns further decreased as crop canopy closure was reached early on regardless of planting pattern. We furthermore conclude that our modelling approach provides promising avenues to further explore crop-weed interactions and aid in the design of crop management strategies that aim at improving crop competitiveness with weeds.
Dynamic Failure of Composite and Sandwich Structures
Abrate, Serge; Rajapakse, Yapa D S
2013-01-01
This book presents a broad view of the current state of the art regarding the dynamic response of composite and sandwich structures subjected to impacts and explosions. Each chapter combines a thorough assessment of the literature with original contributions made by the authors. The first section deals with fluid-structure interactions in marine structures. The first chapter focuses on hull slamming and particularly cases in which the deformation of the structure affects the motion of the fluid during the water entry of flexible hulls. Chapter 2 presents an extensive series of tests underwater and in the air to determine the effects of explosions on composite and sandwich structures. Full-scale structures were subjected to significant explosive charges, and such results are extremely rare in the open literature. Chapter 3 describes a simple geometrical theory of diffraction for describing the interaction of an underwater blast wave with submerged structures. The second section addresses the problem of...
Dynamic analysis of the BPX machine structure
International Nuclear Information System (INIS)
Dahlgen, F.; Citrolo, J.; Knutson, D.; Kalish, M.
1992-01-01
A preliminary analysis of the response of the BPX machine structure to a seismic input was performed. MSC/NASTRAN 5 , a general purpose XXX element computer code, has been used. The purpose of this paper is to assess the probable range of seismically induced stresses and deflections in the machine substructure which connects the machine to the test cell floor, with particular emphasis on the shear pins which will be used to attach the TF coil modules to the machine substructure (for a more detailed description of the shear pins and structure see ref. 4 in these proceedings). The model was developed with sufficient detail to be used subsequently to investigate the transient response to various dynamic loading conditions imposed on the structure by the PF, TF, and Vacuum Vessel, during normal and off-normal operations. The model does not include the mass and stiffness of the building or the building-soil interaction and as such can only be considered an interim assessment of the dynamic response of the machine to the S.S.E.(this is the Safe Shutdown Earthquake which is also the Design XXX Earthquake for all major structural components)
Structured population dynamics: continuous size and discontinuous stage structures.
Buffoni, Giuseppe; Pasquali, Sara
2007-04-01
A nonlinear stochastic model for the dynamics of a population with either a continuous size structure or a discontinuous stage structure is formulated in the Eulerian formalism. It takes into account dispersion effects due to stochastic variability of the development process of the individuals. The discrete equations of the numerical approximation are derived, and an analysis of the existence and stability of the equilibrium states is performed. An application to a copepod population is illustrated; numerical results of Eulerian and Lagrangian models are compared.
30th IMAC, A Conference on Structural Dynamics
Catbas, FN; Mayes, R; Rixen, D; Griffith, DT; Allemang, R; Clerck, J; Klerk, D; Simmermacher, T; Cogan, S; Chauhan, S; Cunha, A; Racic, V; Reynolds, P; Salyards, K; Adams, D; Kerschen, G; Carrella, A; Voormeeren, SN; Allen, MS; Horta, LG; Barthorpe, R; Niezrecki, C; Blough, JR; Vol.1 Topics on the Dynamics of Civil Structures; Vol.2 Topics in Experimental Dynamics Substructuring and Wind Turbine Dynamics; Vol.3 Topics in Nonlinear Dynamics; Vol.4 Topics in Model Validation and Uncertainty Quantification; Vol.5 Topics in Modal Analysis I; Vol.6 Topics in Modal Analysis II
2012-01-01
Topics on the Dynamics of Civil Structures, Volume 1, Proceedings of the 30th IMAC, A Conference and Exposition on Structural Dynamics, 2012, the first volume of six from the Conference, brings together 45 contributions to this important area of research and engineering. The collection presents early findings and case studies on fundamental and applied aspects of Structural Dynamics, including papers on: Human Induced Vibrations Bridge Dynamics Operational Modal Analysis Experimental Techniques and Modeling for Civil Structures System Identification for Civil Structures Method and Technologies for Bridge Monitoring Damage Detection for Civil Structures Structural Modeling Vibration Control Method and Approaches for Civil Structures Modal Testing of Civil Structures.
Application of Time-Delay Absorber to Suppress Vibration of a Dynamical System to Tuned Excitation.
El-Ganaini, W A A; El-Gohary, H A
2014-08-01
In this work, we present a comprehensive investigation of the time delay absorber effects on the control of a dynamical system represented by a cantilever beam subjected to tuned excitation forces. Cantilever beam is one of the most widely used system in too many engineering applications, such as mechanical and civil engineering. The main aim of this work is to control the vibration of the beam at simultaneous internal and combined resonance condition, as it is the worst resonance case. Control is conducted via time delay absorber to suppress chaotic vibrations. Time delays often appear in many control systems in the state, in the control input, or in the measurements. Time delay commonly exists in various engineering, biological, and economical systems because of the finite speed of the information processing. It is a source of performance degradation and instability. Multiple time scale perturbation method is applied to obtain a first order approximation for the nonlinear differential equations describing the system behavior. The different resonance cases are reported and studied numerically. The stability of the steady-state solution at the selected worst resonance case is investigated applying Runge-Kutta fourth order method and frequency response equations via Matlab 7.0 and Maple11. Time delay absorber is effective, but within a specified range of time delay. It is the critical factor in selecting such absorber. Time delay absorber is better than the ordinary one as from the effectiveness point of view. The effects of the different absorber parameters on the system behavior and stability are studied numerically. A comparison with the available published work showed a close agreement with some previously published work.
Structural optimization for nonlinear dynamic response
DEFF Research Database (Denmark)
Dou, Suguang; Strachan, B. Scott; Shaw, Steven W.
2015-01-01
by a single vibrating mode, or by a pair of internally resonant modes. The approach combines techniques from nonlinear dynamics, computational mechanics and optimization, and it allows one to relate the geometric and material properties of structural elements to terms in the normal form for a given resonance......Much is known about the nonlinear resonant response of mechanical systems, but methods for the systematic design of structures that optimize aspects of these responses have received little attention. Progress in this area is particularly important in the area of micro-systems, where nonlinear...... resonant behaviour is being used for a variety of applications in sensing and signal conditioning. In this work, we describe a computational method that provides a systematic means for manipulating and optimizing features of nonlinear resonant responses of mechanical structures that are described...
Dynamics of Correlation Structure in Stock Market
Directory of Open Access Journals (Sweden)
Maman Abdurachman Djauhari
2014-01-01
Full Text Available In this paper a correction factor for Jennrich’s statistic is introduced in order to be able not only to test the stability of correlation structure, but also to identify the time windows where the instability occurs. If Jennrich’s statistic is only to test the stability of correlation structure along predetermined non-overlapping time windows, the corrected statistic provides us with the history of correlation structure dynamics from time window to time window. A graphical representation will be provided to visualize that history. This information is necessary to make further analysis about, for example, the change of topological properties of minimal spanning tree. An example using NYSE data will illustrate its advantages.
Calculating evolutionary dynamics in structured populations.
Directory of Open Access Journals (Sweden)
Charles G Nathanson
2009-12-01
Full Text Available Evolution is shaping the world around us. At the core of every evolutionary process is a population of reproducing individuals. The outcome of an evolutionary process depends on population structure. Here we provide a general formula for calculating evolutionary dynamics in a wide class of structured populations. This class includes the recently introduced "games in phenotype space" and "evolutionary set theory." There can be local interactions for determining the relative fitness of individuals, but we require global updating, which means all individuals compete uniformly for reproduction. We study the competition of two strategies in the context of an evolutionary game and determine which strategy is favored in the limit of weak selection. We derive an intuitive formula for the structure coefficient, sigma, and provide a method for efficient numerical calculation.
The structural dynamics of social class.
Kraus, Michael W; Park, Jun Won
2017-12-01
Individual agency accounts of social class persist in society and even in psychological science despite clear evidence for the role of social structures. This article argues that social class is defined by the structural dynamics of society. Specifically, access to powerful networks, groups, and institutions, and inequalities in wealth and other economic resources shape proximal social environments that influence how individuals express their internal states and motivations. An account of social class that highlights the means by which structures shape and are shaped by individuals guides our understanding of how people move up or down in the social class hierarchy, and provides a framework for interpreting neuroscience studies, experimental paradigms, and approaches that attempt to intervene on social class disparities. Copyright © 2017 Elsevier Ltd. All rights reserved.
Suppressing epidemic spreading by risk-averse migration in dynamical networks
Yang, Han-Xin; Tang, Ming; Wang, Zhen
2018-01-01
In this paper, we study the interplay between individual behaviors and epidemic spreading in a dynamical network. We distribute agents on a square-shaped region with periodic boundary conditions. Every agent is regarded as a node of the network and a wireless link is established between two agents if their geographical distance is less than a certain radius. At each time, every agent assesses the epidemic situation and make decisions on whether it should stay in or leave its current place. An agent will leave its current place with a speed if the number of infected neighbors reaches or exceeds a critical value E. Owing to the movement of agents, the network's structure is dynamical. Interestingly, we find that there exists an optimal value of E leading to the maximum epidemic threshold. This means that epidemic spreading can be effectively controlled by risk-averse migration. Besides, we find that the epidemic threshold increases as the recovering rate increases, decreases as the contact radius increases, and is maximized by an optimal moving speed. Our findings offer a deeper understanding of epidemic spreading in dynamical networks.
Dynamic sign structures in visual art and music
DEFF Research Database (Denmark)
Zeller, Jörg
2006-01-01
Seemingly static meaning carriers in visual art are considered as aspects of holistic dynamical sign structures.......Seemingly static meaning carriers in visual art are considered as aspects of holistic dynamical sign structures....
Dynamics of a structured neuron population
International Nuclear Information System (INIS)
Pakdaman, Khashayar; Salort, Delphine; Perthame, Benoît
2010-01-01
We study the dynamics of assemblies of interacting neurons. For large fully connected networks, the dynamics of the system can be described by a partial differential equation reminiscent of age-structure models used in mathematical ecology, where the 'age' of a neuron represents the time elapsed since its last discharge. The nonlinearity arises from the connectivity J of the network. We prove some mathematical properties of the model that are directly related to qualitative properties. On the one hand, we prove that it is well-posed and that it admits stationary states which, depending upon the connectivity, can be unique or not. On the other hand, we study the long time behaviour of solutions; both for small and large J, we prove the relaxation to the steady state describing asynchronous firing of the neurons. In the middle range, numerical experiments show that periodic solutions appear expressing re-synchronization of the network and asynchronous firing
The Dynamics and Structures of Adsorbed Surfaces
DEFF Research Database (Denmark)
Nielsen, M; Ellenson, W. D.; McTague, J. P.
1978-01-01
. Elastic neutron diffraction measurements, determining the two-dimensional structural ordering of the adsorbed films, have been performed on layers of N2, Ar, H2, D2, O2, Kr, and He. Measurements on layers of larger molecules such as CD4 and ND3 have also been reported. Inelastic neutron scattering...... measurements, studying the dynamics of the adsorbed films are only possible in a few especially favourable cases such as 36Ar and D2 films, where the coherent phonon scattering cross-sections are very large. In other cases incoherent scattering from hydrogen can give information about e.g. the mobility...
Structural dynamics of turbo-machines
Rangwala, AS
2009-01-01
The book presents a detailed and comprehensive treatment of structural vibration evaluation of turbo-machines. Starting with the fundamentals of the theory of vibration as related to various aspects of rotating machines, the dynamic analysis procedures of a broad spectrum of turbo-machines is covered. An in-depth procedure for analyzing the torsional and flexural oscillations of the components and of the rotor-bearing system is presented. The latest trends in design and analysis are presented, chief among them: Blade and coupled disk-blade mod
Dynamical structure of pure Lovelock gravity
Dadhich, Naresh; Durka, Remigiusz; Merino, Nelson; Miskovic, Olivera
2016-03-01
We study the dynamical structure of pure Lovelock gravity in spacetime dimensions higher than four using the Hamiltonian formalism. The action consists of a cosmological constant and a single higher-order polynomial in the Riemann tensor. Similarly to the Einstein-Hilbert action, it possesses a unique constant curvature vacuum and charged black hole solutions. We analyze physical degrees of freedom and local symmetries in this theory. In contrast to the Einstein-Hilbert case, the number of degrees of freedom depends on the background and can vary from zero to the maximal value carried by the Lovelock theory.
International Nuclear Information System (INIS)
Cao, Fangyu; Yang, Bao
2014-01-01
Highlights: • A new method for supercooling suppression of microPCMs by optimizing the structure of the microcapsule shell. • Large effective latent heat (up to 213 J/g) of the microPCMs, much higher than those using additive as nucleating agents. • Change of shell composition and structure significantly affects the phase transition processes of the encapsulated PCMs. • The latent heat of the shell-induced phase transition is maximized, reaching 83.7% of the latent heat of bulk octadecane. • Hollow spheres with porous rather than solid resin shell are also formed when the SDS concentration is very high. - Abstract: A new method for supercooling suppression of microencapsulated phase change materials (PCMs) has been developed by optimizing the composition and structure of the microcapsule resin shell. The microcapsules comprising paraffin octadecane encapsulated in melamine–formaldehyde resin shell were synthesized with the use the oil-in-water emulsion technique. These PCM microcapsules are 5–15 μm in diameter. The supercooling of these octadecane microcapsules can be as large as 13.6 °C, when the homogeneous nucleation is dominant during the melt crystallization into the thermodynamically stable triclinic phase. It is discovered that the homogeneous nucleation can be mediated by shell-induced nucleation of the triclinic phase and the metastable rotator phase when the shell composition and structure are optimized, without need of any nucleating additives. The effects of synthesis parameters, such as ratio of melamine to formaldehyde, pH of pre-polymer, and pH of emulsion, on the phase transition properties of the octadecane microcapsules have been investigated systemically. The optimum synthesis conditions have been identified in terms of minimizing the supercooling while maintaining heat capacity. Potential applications of this type of phase changeable microcapsules include high heat capacity thermal fluids, thermal management in smart buildings
Band structure dynamics in indium wires
Chávez-Cervantes, M.; Krause, R.; Aeschlimann, S.; Gierz, I.
2018-05-01
One-dimensional indium wires grown on Si(111) substrates, which are metallic at high temperatures, become insulating below ˜100 K due to the formation of a charge density wave (CDW). The physics of this transition is not conventional and involves a multiband Peierls instability with strong interband coupling. This CDW ground state is readily destroyed with femtosecond laser pulses resulting in a light-induced insulator-to-metal phase transition. The current understanding of this transition remains incomplete, requiring measurements of the transient electronic structure to complement previous investigations of the lattice dynamics. Time- and angle-resolved photoemission spectroscopy with extreme ultraviolet radiation is applied to this end. We find that the transition from the insulating to the metallic band structure occurs within ˜660 fs, which is a fraction of the amplitude mode period. The long lifetime of the transient state (>100 ps) is attributed to trapping in a metastable state in accordance with previous work.
Structure and dynamics of molten salts
International Nuclear Information System (INIS)
Rovere, M.; Tosi, M.P.
1986-02-01
Modern techniques of liquid state physics have been successfully used over the last decade to probe the microscopic structure and dynamics of a variety of multicomponent liquids in which relative ordering of the species is present near freezing. The alkali halides are prototypes for this specific type of short range order in relation to the nature of bonding, but the systems in question include also other monovalent and polyvalent metal-ion halides, alkali-based intermetallic compounds, and chalcogen-based alloys. A viewpoint is taken in this review which gives attention to relations between liquid and solid phase properties across melting for compound systems at stoichiometric composition. In addition, large deviations from stoichiometry can be realized in the liquid phase, to display trends of evolution of structure, bonding and electronic states with composition. (author)
Molecular structures and intramolecular dynamics of pentahalides
Ischenko, A. A.
2017-03-01
This paper reviews advances of modern gas electron diffraction (GED) method combined with high-resolution spectroscopy and quantum chemical calculations in studies of the impact of intramolecular dynamics in free molecules of pentahalides. Some recently developed approaches to the electron diffraction data interpretation, based on direct incorporation of the adiabatic potential energy surface parameters to the diffraction intensity are described. In this way, complementary data of different experimental and computational methods can be directly combined for solving problems of the molecular structure and its dynamics. The possibility to evaluate some important parameters of the adiabatic potential energy surface - barriers to pseudorotation and saddle point of intermediate configuration from diffraction intensities in solving the inverse GED problem is demonstrated on several examples. With increasing accuracy of the electron diffraction intensities and the development of the theoretical background of electron scattering and data interpretation, it has become possible to investigate complex nuclear dynamics in fluxional systems by the GED method. Results of other research groups are also included in the discussion.
Structural Dynamics of Tropical Moist Forest Gaps
Hunter, Maria O.; Keller, Michael; Morton, Douglas; Cook, Bruce; Lefsky, Michael; Ducey, Mark; Saleska, Scott; de Oliveira, Raimundo Cosme; Schietti, Juliana
2015-01-01
Gap phase dynamics are the dominant mode of forest turnover in tropical forests. However, gap processes are infrequently studied at the landscape scale. Airborne lidar data offer detailed information on three-dimensional forest structure, providing a means to characterize fine-scale (1 m) processes in tropical forests over large areas. Lidar-based estimates of forest structure (top down) differ from traditional field measurements (bottom up), and necessitate clear-cut definitions unencumbered by the wisdom of a field observer. We offer a new definition of a forest gap that is driven by forest dynamics and consistent with precise ranging measurements from airborne lidar data and tall, multi-layered tropical forest structure. We used 1000 ha of multi-temporal lidar data (2008, 2012) at two sites, the Tapajos National Forest and Ducke Reserve, to study gap dynamics in the Brazilian Amazon. Here, we identified dynamic gaps as contiguous areas of significant growth, that correspond to areas > 10 m2, with height gap at Tapajos National Forest (4.8 %) as compared to Ducke Reserve (2.0 %). On average, gaps were smaller at Ducke Reserve and closed slightly more rapidly, with estimated height gains of 1.2 m y-1 versus 1.1 m y-1 at Tapajos. At the Tapajos site, height growth in gap centers was greater than the average height gain in gaps (1.3 m y-1 versus 1.1 m y-1). Rates of height growth between lidar acquisitions reflect the interplay between gap edge mortality, horizontal ingrowth and gap size at the two sites. We estimated that approximately 10 % of gap area closed via horizontal ingrowth at Ducke Reserve as opposed to 6 % at Tapajos National Forest. Height loss (interpreted as repeat damage and/or mortality) and horizontal ingrowth accounted for similar proportions of gap area at Ducke Reserve (13 % and 10 %, respectively). At Tapajos, height loss had a much stronger signal (23 % versus 6 %) within gaps. Both sites demonstrate limited gap contagiousness defined by an
Chemical Structure and Dynamics annual report 1997
International Nuclear Information System (INIS)
Colson, S.D.; McDowell, R.S.
1998-03-01
The Chemical Structure and Dynamics (CS and D) program is a major component of the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL), developed by Pacific Northwest National Laboratory (PNNL) to provide a state-of-the-art collaborative facility for studies of chemical structure and dynamics. The authors respond to the need for a fundamental, molecular level understanding of chemistry at a wide variety of environmentally important interfaces by: (1) extending the experimental characterization and theoretical description of chemical reactions to encompass the effects of condensed media and interfaces; (2) developing a multidisciplinary capability for describing interfacial chemical processes within which the new knowledge generated can be brought to bear on complex phenomena in environmental chemistry and in nuclear waste processing and storage; and (3) developing state-of-the-art analytical methods for characterizing complex materials of the types found in stored wastes and contaminated soils, and for detecting and monitoring trace atmospheric species. The focus of the research is defined primarily by DOE's environmental problems: fate and transport of contaminants in the subsurface environment, processing and storage of waste materials, cellular effects of chemical and radiological insult, and atmospheric chemistry as it relates to air quality and global change. Twenty-seven projects are described under the following topical sections: Reaction mechanisms at interfaces; High-energy processes at environmental interfaces; Cluster models of the condensed phase; and Miscellaneous
Modeling Insurgent Network Structure and Dynamics
Gabbay, Michael; Thirkill-Mackelprang, Ashley
2010-03-01
We present a methodology for mapping insurgent network structure based on their public rhetoric. Indicators of cooperative links between insurgent groups at both the leadership and rank-and-file levels are used, such as joint policy statements or joint operations claims. In addition, a targeting policy measure is constructed on the basis of insurgent targeting claims. Network diagrams which integrate these measures of insurgent cooperation and ideology are generated for different periods of the Iraqi and Afghan insurgencies. The network diagrams exhibit meaningful changes which track the evolution of the strategic environment faced by insurgent groups. Correlations between targeting policy and network structure indicate that insurgent targeting claims are aimed at establishing a group identity among the spectrum of rank-and-file insurgency supporters. A dynamical systems model of insurgent alliance formation and factionalism is presented which evolves the relationship between insurgent group dyads as a function of their ideological differences and their current relationships. The ability of the model to qualitatively and quantitatively capture insurgent network dynamics observed in the data is discussed.
Chemical Structure and Dynamics annual report 1997
Energy Technology Data Exchange (ETDEWEB)
Colson, S.D.; McDowell, R.S.
1998-03-01
The Chemical Structure and Dynamics (CS and D) program is a major component of the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL), developed by Pacific Northwest National Laboratory (PNNL) to provide a state-of-the-art collaborative facility for studies of chemical structure and dynamics. The authors respond to the need for a fundamental, molecular level understanding of chemistry at a wide variety of environmentally important interfaces by: (1) extending the experimental characterization and theoretical description of chemical reactions to encompass the effects of condensed media and interfaces; (2) developing a multidisciplinary capability for describing interfacial chemical processes within which the new knowledge generated can be brought to bear on complex phenomena in environmental chemistry and in nuclear waste processing and storage; and (3) developing state-of-the-art analytical methods for characterizing complex materials of the types found in stored wastes and contaminated soils, and for detecting and monitoring trace atmospheric species. The focus of the research is defined primarily by DOE`s environmental problems: fate and transport of contaminants in the subsurface environment, processing and storage of waste materials, cellular effects of chemical and radiological insult, and atmospheric chemistry as it relates to air quality and global change. Twenty-seven projects are described under the following topical sections: Reaction mechanisms at interfaces; High-energy processes at environmental interfaces; Cluster models of the condensed phase; and Miscellaneous.
Directory of Open Access Journals (Sweden)
Pascal eVrticka
2013-02-01
Full Text Available Emotion regulation is crucial for successfully engaging in social interactions. Yet, little is known about the neural mechanisms controlling behavioral responses to emotional expressions perceived in the face of other people, which constitute a key element of interpersonal communication. Here, we investigated brain systems involved in social emotion perception and regulation, using functional magnetic resonance imaging (fMRI in 20 healthy participants who saw dynamic facial expressions of either happiness or sadness, and were asked to either imitate the expression or to suppress any expression on their own face (in addition to a gender judgment control task. fMRI results revealed higher activity in regions associated with emotion (e.g., the insula, motor function (e.g., motor cortex, and theory of mind during imitation. Activity in dorsal cingulate cortex was also increased during imitation, possibly reflecting greater action monitoring or conflict with own feeling states. In addition, premotor regions were more strongly activated during both imitation and suppression, suggesting a recruitment of motor control for both the production and inhibition of emotion expressions. Expressive suppression produced increases in dorsolateral and lateral prefrontal cortex typically related to cognitive control. These results suggest that voluntary imitation and expressive suppression modulate brain responses to emotional signals perceived from faces, by up- and down-regulating activity in distributed subcortical and cortical networks that are particularly involved in emotion, action monitoring, and cognitive control.
Application of smart structure concepts to vibration suppression of a cryocooler coldfinger
International Nuclear Information System (INIS)
Glaser, R.J.; Kuo, Chinpo, Garba, J.A.
1993-01-01
A flight experiment demonstrating vibration suppression using smart structure technology is being flown on a small British satellite in late 1993. Piezo actuators are used to suppress motion of the tip of a cryocooler coldfinger in three dimensions. Two actuation methods are being demonstrated: low voltage piezo translators and applique ceramics. The applique ceramics stretch the coldfinger to cancel the tip motion and is discussed in detail in a companion paper. Commercially available piezo translators displace the entire cryocooler to cancel the motion of the tip of the coldfinger as measured by three eddy current transducers. Two types of control systems are being demonstrated: a real time analog control system using position feedback, and a digital feed forward controller that updates it's waveform every second or so. The flight experiment is a technology demonstration. The coldfinger is not being used to cool an operational sensor. Instead, the cooler vibration experiment will demonstrate that this class of hardware can be flown successfully. This includes qualification of the piezos for launch, and for the space environment; the design and qualification of low-power flight piezo drivers; and design and implementation of the control systems
Genomic structural variation-mediated allelic suppression causes hybrid male sterility in rice.
Shen, Rongxin; Wang, Lan; Liu, Xupeng; Wu, Jiang; Jin, Weiwei; Zhao, Xiucai; Xie, Xianrong; Zhu, Qinlong; Tang, Huiwu; Li, Qing; Chen, Letian; Liu, Yao-Guang
2017-11-03
Hybrids between divergent populations commonly show hybrid sterility; this reproductive barrier hinders hybrid breeding of the japonica and indica rice (Oryza sativa L.) subspecies. Here we show that structural changes and copy number variation at the Sc locus confer japonica-indica hybrid male sterility. The japonica allele, Sc-j, contains a pollen-essential gene encoding a DUF1618-domain protein; the indica allele, Sc-i, contains two or three tandem-duplicated ~ 28-kb segments, each carrying an Sc-j-homolog with a distinct promoter. In Sc-j/Sc-i hybrids, the high-expression of Sc-i in sporophytic cells causes suppression of Sc-j expression in pollen and selective abortion of Sc-j-pollen, leading to transmission ratio distortion. Knocking out one or two of the three Sc-i copies by CRISPR/Cas9 rescues Sc-j expression and male fertility. Our results reveal the gene dosage-dependent allelic suppression as a mechanism of hybrid incompatibility, and provide an effective approach to overcome the reproductive barrier for hybrid breeding.
Mahmoudpour, Sanaz; Attarnejad, Reza; Behnia, Cambyse
2011-01-01
Analysis and design of structures subjected to arbitrary dynamic loadings especially earthquakes have been studied during past decades. In practice, the effects of soil-structure interaction on the dynamic response of structures are usually neglected. In this study, the effect of soil-structure interaction on the dynamic response of structures has been examined. The substructure method using dynamic stiffness of soil is used to analyze soil-structure system. A coupled model based on finite el...
Abramov, R. V.
2011-12-01
Chaotic multiscale dynamical systems are common in many areas of science, one of the examples being the interaction of the low-frequency dynamics in the atmosphere with the fast turbulent weather dynamics. One of the key questions about chaotic multiscale systems is how the fast dynamics affects chaos at the slow variables, and, therefore, impacts uncertainty and predictability of the slow dynamics. Here we demonstrate that the linear slow-fast coupling with the total energy conservation property promotes the suppression of chaos at the slow variables through the rapid mixing at the fast variables, both theoretically and through numerical simulations. A suitable mathematical framework is developed, connecting the slow dynamics on the tangent subspaces to the infinite-time linear response of the mean state to a constant external forcing at the fast variables. Additionally, it is shown that the uncoupled dynamics for the slow variables may remain chaotic while the complete multiscale system loses chaos and becomes completely predictable at the slow variables through increasing chaos and turbulence at the fast variables. This result contradicts the common sense intuition, where, naturally, one would think that coupling a slow weakly chaotic system with another much faster and much stronger chaotic system would result in general increase of chaos at the slow variables.
Nonparametric inference of network structure and dynamics
Peixoto, Tiago P.
The network structure of complex systems determine their function and serve as evidence for the evolutionary mechanisms that lie behind them. Despite considerable effort in recent years, it remains an open challenge to formulate general descriptions of the large-scale structure of network systems, and how to reliably extract such information from data. Although many approaches have been proposed, few methods attempt to gauge the statistical significance of the uncovered structures, and hence the majority cannot reliably separate actual structure from stochastic fluctuations. Due to the sheer size and high-dimensionality of many networks, this represents a major limitation that prevents meaningful interpretations of the results obtained with such nonstatistical methods. In this talk, I will show how these issues can be tackled in a principled and efficient fashion by formulating appropriate generative models of network structure that can have their parameters inferred from data. By employing a Bayesian description of such models, the inference can be performed in a nonparametric fashion, that does not require any a priori knowledge or ad hoc assumptions about the data. I will show how this approach can be used to perform model comparison, and how hierarchical models yield the most appropriate trade-off between model complexity and quality of fit based on the statistical evidence present in the data. I will also show how this general approach can be elegantly extended to networks with edge attributes, that are embedded in latent spaces, and that change in time. The latter is obtained via a fully dynamic generative network model, based on arbitrary-order Markov chains, that can also be inferred in a nonparametric fashion. Throughout the talk I will illustrate the application of the methods with many empirical networks such as the internet at the autonomous systems level, the global airport network, the network of actors and films, social networks, citations among
Structure, dynamics, and function of biomolecules
International Nuclear Information System (INIS)
Frauenfelder, H.; Berendzen, J.R.; Garcia, A.; Gupta, G.; Olah, G.A.; Terwilliger, T.C.; Trewhella, J.; Wood, C.C.; Woodruff, W.H.
1998-01-01
This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The authors enhanced Los Alamos' core competency in Bioscience and Biotechnology by building on present strengths in experimental techniques, theory, high-performance computing, modeling, and simulation applied to biomolecular structure, dynamics, and function. Specifically, the authors strengthened their capabilities in neutron/x-ray scattering, x-ray crystallography, NMR, laser, and optical spectroscopies. Initially they focused on supporting the Los alamos Neutron Science Center (LANSCE) in the design and implementation of new neutron scattering instrumentation, they developed new methods for analysis of scattering data, and they developed new projects to study the structures of biomolecular complexes. The authors have also worked to strengthen interactions between theory and experiment, and between the biological and physical sciences. They sponsored regular meetings of members from all interested LANL technical divisions, and supported two lecture series: ''Biology for Physicists'' and ''Issues in Modern Biology''. They also supported the formation of interdisciplinary/inter-divisional teams to develop projects in science-based bioremediation and an integrated structural biology resource. Finally, they successfully worked with a multidisciplinary team to put forward the Laboratory's Genome and Beyond tactical goal
Barnes, Rachel D; Sawaoka, Takuya; White, Marney A; Masheb, Robin M; Grilo, Carlos M
2013-01-01
Prior research on the relations among eating behaviors and thought suppression is limited to a measure of general thought suppression, the White Bear Suppression Inventory. To address this limitation, researchers recently validated the Food Thought Suppression Inventory (FTSI). Analyses using this measure suggest that food thought suppression is distinct from and is more predictive of eating disorder psychopathology than is general thought suppression. The FTSI, however, has not yet been validated in clinical samples. The purpose of the current study is to examine the factor structure and clinical correlates of the FTSI within treatment seeking obese women with binge eating disorder (BED; N=128). Analyses revealed a valid and reliable one-factor measure of food thought suppression that was related to higher levels of eating and general psychopathology. The findings provide evidence for the use of the FTSI with obese women with BED. Future research should examine the psychometric properties of the FTSI within larger and more diverse samples. Copyright © 2012. Published by Elsevier Ltd.
Plasma and current structures in dynamical pinches
International Nuclear Information System (INIS)
Butov, I.Ya.; Matveev, Yu.V.
1981-01-01
Dynamics of plasma layers and current structure in aZ-pinch device has been experimentally investigated. It is found that shaping of a main current envelope is ended with its explosion-like expansion, the pinch decaying after compression to separated current filaments. It is also shown that filling of a region outside the pinch with plasma and currents alternating in directions occurs owing to interaction of current loops (inductions) formed in a magnetic piston during its compression with reflected shock wave. Current circulating in the loops sometimes exceeds 1.5-2 times the current of discharge circuit. The phenomena noted appear during development of superheat instability and can be realized, for example, in theta-pinches, plasma focuses, tokamaks. The experiments were carried out at the Dynamic Zeta-pinch device at an energy reserse of up to 15 kJ (V 0 =24 kV) in a capacitor bank. Half-period of the discharge current is 9 μs; Isub(max)=3.5x10sup(5) A. Back current guide surrounding a china chamber of 28 cm diameter and 50 cm length is made in the form of a hollow cylinder. Initial chamber vacuum is 10 -6 torr [ru
Wheat yield dynamics: a structural econometric analysis.
Sahin, Afsin; Akdi, Yilmaz; Arslan, Fahrettin
2007-10-15
In this study we initially have tried to explore the wheat situation in Turkey, which has a small-open economy and in the member countries of European Union (EU). We have observed that increasing the wheat yield is fundamental to obtain comparative advantage among countries by depressing domestic prices. Also the changing structure of supporting schemes in Turkey makes it necessary to increase its wheat yield level. For this purpose, we have used available data to determine the dynamics of wheat yield by Ordinary Least Square Regression methods. In order to find out whether there is a linear relationship among these series we have checked each series whether they are integrated at the same order or not. Consequently, we have pointed out that fertilizer usage and precipitation level are substantial inputs for producing high wheat yield. Furthermore, in respect for our model, fertilizer usage affects wheat yield more than precipitation level.
Chemical structure and dynamics. Annual report 1994
Energy Technology Data Exchange (ETDEWEB)
Colson, S.D.
1995-07-01
The Chemical Structure and Dynamics program was organized as a major component of Pacific Northwest Laboratory`s Environmental and Molecular Sciences Laboratory (EMSL), a state-of-the-art collaborative facility for studies of chemical structure and dynamics. Our program responds to the need for a fundamental, molecular-level understanding of chemistry at the wide variety of environmentally important interfaces by (1) extending the experimental characterization and theoretical description of chemical reactions to encompass the effects of condensed media and interfaces, and (2) developing a multidisciplinary capability for describing interfacial chemical processes within which the new knowledge generated can be brought to bear on complex phenomena in environmental chemistry and in nuclear waste processing and storage. This research effort was initiated in 1989 and will continue to evolve over the next few years into a program of rigorous studies of fundamental molecular processes in model systems, such as well-characterized surfaces, single-component solutions, clusters, and biological molecules; and studies of complex systems found in the environment (multispecies, multiphase solutions; solid/liquid, liquid/liquid, and gas/surface interfaces; colloidal dispersions; ultrafine aerosols; and functioning biological systems). The success of this program will result in the achievement of a quantitative understanding of chemical reactions at interfaces, and more generally in condensed media, that is comparable to that currently available for gas-phase reactions. This understanding will form the basis for the development of a priori theories for predictions of macroscopic chemical behavior in condensed and heterogeneous media, adding significantly to the value of field-scale environmental models, the prediction of short- and long-term nuclear waste storage stabilities, and other problems related to the primary missions of the DOE.
MULTISCALE DYNAMICS OF SOLAR MAGNETIC STRUCTURES
International Nuclear Information System (INIS)
Uritsky, Vadim M.; Davila, Joseph M.
2012-01-01
Multiscale topological complexity of the solar magnetic field is among the primary factors controlling energy release in the corona, including associated processes in the photospheric and chromospheric boundaries. We present a new approach for analyzing multiscale behavior of the photospheric magnetic flux underlying these dynamics as depicted by a sequence of high-resolution solar magnetograms. The approach involves two basic processing steps: (1) identification of timing and location of magnetic flux origin and demise events (as defined by DeForest et al.) by tracking spatiotemporal evolution of unipolar and bipolar photospheric regions, and (2) analysis of collective behavior of the detected magnetic events using a generalized version of the Grassberger-Procaccia correlation integral algorithm. The scale-free nature of the developed algorithms makes it possible to characterize the dynamics of the photospheric network across a wide range of distances and relaxation times. Three types of photospheric conditions are considered to test the method: a quiet photosphere, a solar active region (NOAA 10365) in a quiescent non-flaring state, and the same active region during a period of M-class flares. The results obtained show (1) the presence of a topologically complex asymmetrically fragmented magnetic network in the quiet photosphere driven by meso- and supergranulation, (2) the formation of non-potential magnetic structures with complex polarity separation lines inside the active region, and (3) statistical signatures of canceling bipolar magnetic structures coinciding with flaring activity in the active region. Each of these effects can represent an unstable magnetic configuration acting as an energy source for coronal dissipation and heating.
Annual Report 1998: Chemical Structure and Dynamics
Energy Technology Data Exchange (ETDEWEB)
SD Colson; RS McDowell
1999-05-10
The Chemical Structure and Dynamics (CS&D) program is a major component of the William R. Wiley Environmental Molecular Sciences Labo- ratory (EMSL), developed by Pacific Northwest National Laboratory (PNNL) to provide a state-of- the-art collaborative facility for studies of chemical structure and dynamics. We respond to the need for a fundamental, molecular-level understanding of chemistry at a wide variety of environmentally important interfaces by (1) extending the experimental characterization and theoretical description of chemical reactions to encompass the effects of condensed media and interfaces; (2) developing a multidisciplinary capability for describing interracial chemical processes within which the new knowledge generated can be brought to bear on complex phenomena in envi- ronmental chemistry and in nuclear waste proc- essing and storage; and (3) developing state-of- the-art analytical methods for characterizing com- plex materials of the types found in stored wastes and contaminated soils, and for detecting and monitoring trace atmospheric species. Our program aims at achieving a quantitative understanding of chemical reactions at interfaces and, more generally, in condensed media, compa- rable to that currently available for gas-phase reactions. This understanding will form the basis for the development of a priori theories for pre- dicting macroscopic chemical behavior in con- densed and heterogeneous media, which will add significantly to the value of field-scale envi- ronmental models, predictions of short- and long- term nuclear waste storage stabilities, and other areas related to the primary missions of the U.S. Department of Energy (DOE).
Kousi, Evanthia; Smith, Joely; Ledger, Araminta E; Scurr, Erica; Allen, Steven; Wilson, Robin M; O'Flynn, Elizabeth; Pope, Romney J E; Leach, Martin O; Schmidt, Maria A
2018-01-01
To propose a method to quantify T 1 and contrast agent uptake in breast dynamic contrast-enhanced (DCE) examinations undertaken with standard clinical fat-suppressed MRI sequences and to demonstrate the proposed approach by comparing the enhancement characteristics of lobular and ductal carcinomas. A standard fat-suppressed DCE of the breast was performed at 1.5 T (Siemens Aera), followed by the acquisition of a proton density (PD)-weighted sequence, also fat suppressed. Both sequences were characterized with test objects (T 1 ranging from 30 ms to 2,400 ms) and calibration curves were obtained to enable T 1 calculation. The reproducibility and accuracy of the calibration curves were also investigated. Healthy volunteers and patients were scanned with Ethics Committee approval. The effect of B 0 field inhomogeneity was assessed in test objects and healthy volunteers. The T 1 of breast tumors was calculated at different time points (pre-, peak-, and post-contrast agent administration) for 20 patients, pre-treatment (10 lobular and 10 ductal carcinomas) and the two cancer types were compared (Wilcoxon rank-sum test). The calibration curves proved to be highly reproducible (coefficient of variation under 10%). T 1 measurements were affected by B 0 field inhomogeneity, but frequency shifts below 50 Hz introduced only 3% change to fat-suppressed T 1 measurements of breast parenchyma in volunteers. The values of T 1 measured pre-, peak-, and post-contrast agent administration demonstrated that the dynamic range of the DCE sequence was correct, that is, image intensity is approximately directly proportional to 1/T 1 for that range. Significant differences were identified in the width of the distributions of the post-contrast T 1 values between lobular and ductal carcinomas (P contrast T 1 values, potentially related to their infiltrative growth pattern. This work has demonstrated the feasibility of fat-suppressed T 1 measurements as a tool for clinical studies. The
Structural basis for the suppression of skin cancers by DNA polymerase [eta
Energy Technology Data Exchange (ETDEWEB)
Silverstein, Timothy D.; Johnson, Robert E.; Jain, Rinku; Prakash, Louise; Prakash, Satya; Aggarwal, Aneel K. (Texas-MED); (Mount Sinai Hospital)
2010-09-13
DNA polymerase {eta} (Pol{eta}) is unique among eukaryotic polymerases in its proficient ability for error-free replication through ultraviolet-induced cyclobutane pyrimidine dimers, and inactivation of Pol{eta} (also known as POLH) in humans causes the variant form of xeroderma pigmentosum (XPV). We present the crystal structures of Saccharomyces cerevisiae Pol{eta} (also known as RAD30) in ternary complex with a cis-syn thymine-thymine (T-T) dimer and with undamaged DNA. The structures reveal that the ability of Pol{eta} to replicate efficiently through the ultraviolet-induced lesion derives from a simple and yet elegant mechanism, wherein the two Ts of the T-T dimer are accommodated in an active site cleft that is much more open than in other polymerases. We also show by structural, biochemical and genetic analysis that the two Ts are maintained in a stable configuration in the active site via interactions with Gln55, Arg73 and Met74. Together, these features define the basis for Pol{eta}'s action on ultraviolet-damaged DNA that is crucial in suppressing the mutagenic and carcinogenic consequences of sun exposure, thereby reducing the incidence of skin cancers in humans.
Indoor footstep localization from structural dynamics instrumentation
Poston, Jeffrey D.; Buehrer, R. Michael; Tarazaga, Pablo A.
2017-05-01
Measurements from accelerometers originally deployed to measure a building's structural dynamics can serve a new role: locating individuals moving within a building. Specifically, this paper proposes measurements of footstep-generated vibrations as a novel source of information for localization. The complexity of wave propagation in a building (e.g., dispersion and reflection) limits the utility of existing algorithms designed to locate, for example, the source of sound in a room or radio waves in free space. This paper develops enhancements for arrival time determination and time difference of arrival localization in order to address the complexities posed by wave propagation within a building's structure. Experiments with actual measurements from an instrumented public building demonstrate the potential of locating footsteps to sub-meter accuracy. Furthermore, this paper explains how to forecast performance in other buildings with different sensor configurations. This localization capability holds the potential to assist public safety agencies in building evacuation and incidence response, to facilitate occupancy-based optimization of heating or cooling and to inform facility security.
Active vibration suppression of self-excited structures using an adaptive LMS algorithm
Danda Roy, Indranil
The purpose of this investigation is to study the feasibility of an adaptive feedforward controller for active flutter suppression in representative linear wing models. The ability of the controller to suppress limit-cycle oscillations in wing models having root springs with freeplay nonlinearities has also been studied. For the purposes of numerical simulation, mathematical models of a rigid and a flexible wing structure have been developed. The rigid wing model is represented by a simple three-degree-of-freedom airfoil while the flexible wing is modelled by a multi-degree-of-freedom finite element representation with beam elements for bending and rod elements for torsion. Control action is provided by one or more flaps attached to the trailing edge and extending along the entire wing span for the rigid model and a fraction of the wing span for the flexible model. Both two-dimensional quasi-steady aerodynamics and time-domain unsteady aerodynamics have been used to generate the airforces in the wing models. An adaptive feedforward controller has been designed based on the filtered-X Least Mean Squares (LMS) algorithm. The control configuration for the rigid wing model is single-input single-output (SISO) while both SISO and multi-input multi-output (MIMO) configurations have been applied on the flexible wing model. The controller includes an on-line adaptive system identification scheme which provides the LMS controller with a reasonably accurate model of the plant. This enables the adaptive controller to track time-varying parameters in the plant and provide effective control. The wing models in closed-loop exhibit highly damped responses at airspeeds where the open-loop responses are destructive. Simulations with the rigid and the flexible wing models in a time-varying airstream show a 63% and 53% increase, respectively, over their corresponding open-loop flutter airspeeds. The ability of the LMS controller to suppress wing store flutter in the two models has
Structure-preserving integrators in nonlinear structural dynamics and flexible multibody dynamics
2016-01-01
This book focuses on structure-preserving numerical methods for flexible multibody dynamics, including nonlinear elastodynamics and geometrically exact models for beams and shells. It also deals with the newly emerging class of variational integrators as well as Lie-group integrators. It discusses two alternative approaches to the discretization in space of nonlinear beams and shells. Firstly, geometrically exact formulations, which are typically used in the finite element community and, secondly, the absolute nodal coordinate formulation, which is popular in the multibody dynamics community. Concerning the discretization in time, the energy-momentum method and its energy-decaying variants are discussed. It also addresses a number of issues that have arisen in the wake of the structure-preserving discretization in space. Among them are the parameterization of finite rotations, the incorporation of algebraic constraints and the computer implementation of the various numerical methods. The practical application...
Matrix of transmission in structural dynamics
International Nuclear Information System (INIS)
Mukherjee, S.
1975-01-01
Within the last few years numerous papers have been published on the subject of matrix method in elasto-mechanics. 'Matrix of Transmission' is one of the methods in this field which has gained considerable attention in recent years. The basic philosophy adopted in this method is based on the idea of breaking up a complicated system into component parts with simple elastic and dynamic properties which can be readily expressed in matrix form. These component matrices are considered as building blocks, which are fitted together according to a set of predetermined rules which then provide the static and dynamic properties of the entire system. A common type of system occuring in engineering practice consists of a number of elements linked together end to end in the form of a chain. The 'Transfer Matrix' is ideally suited for such a system, because only successive multiplication is necessary to connect these elements together. The number of degrees of freedom and intermediate conditions present no difficulty. Although the 'Transfer Matrix' method is suitable for the treatment of branched and coupled systems its application to systems which do not have predominant chain topology is not effective. Apart from the requirement that the system be linearely elastic, no other restrictions are made. In this paper, it is intended to give a general outline and theoretical formulation of 'Transfer Matrix' and then its application to actual problems in structural dynamics related to seismic analysis. The natural frequencies of a freely vibrating elastic system can be found by applying proper end conditions. The end conditions will yield the frequency determinate to zero. By using a suitable numerical method, the natural frequencies and mode shapes are determined by making a frequency sweep within the range of interest. Results of an analysis of a typical nuclear building by this method show very close agreement with the results obtained by using ASKA and SAP IV program. Therefore
Study on Human-structure Dynamic Interaction in Civil Engineering
Gao, Feng; Cao, Li Lin; Li, Xing Hua
2018-06-01
The research of human-structure dynamic interaction are reviewed. Firstly, the influence of the crowd load on structural dynamic characteristics is introduced and the advantages and disadvantages of different crowd load models are analyzed. Then, discussing the influence of structural vibration on the human-induced load, especially the influence of different stiffness structures on the crowd load. Finally, questions about human-structure interaction that require further study are presented.
International Nuclear Information System (INIS)
Boudreaux, J.F.; Ebadian, M.A.; Williams, P.T.; Dua, S.K.
1998-01-01
Hanford, Fernald, Savannah River, and other sites are currently reviewing technologies that can be implemented to demolish buildings in a cost-effective manner. In order to demolish a structure properly and, at the same time, minimize the amount of dust generated from a given technology, an evaluation must be conducted to choose the most appropriate dust suppression technology given site-specific conditions. Thus, the purpose of this research, which was carried out at the Hemispheric Center for Environmental Technology (HCET) at Florida International University, was to conduct an experimental study of dust aerosol abatement (dust suppression) methods as applied to nuclear D and D. This experimental study targeted the problem of dust suppression during the demolition of nuclear facilities. The resulting data were employed to assist in the development of mathematical correlations that can be applied to predict dust generation during structural demolition
Simulating CubeSat Structure Deployment Dynamics, Phase I
National Aeronautics and Space Administration — There is high value in simulating the nonlinear dynamics of stowing, deploying, and performance of deployable space structures, especially given the profound...
Structural dynamics in fast reactor accident analysis
International Nuclear Information System (INIS)
Fistedis, S.H.
1975-01-01
Analyses and codes are under development combining the hydrodynamics and solid mechanics (and more recently the bubble dynamics) phenomena to gage the stresses, strains, and deformations of important primary components, as well as the overall adequacy of primary and secondary containments. An arbitrary partition of the structural components treated evolves into (1) a core mechanics effort; and (2) a primary system and containment program. The primary system and containment program treats the structural response of components beyond the core, starting with the core barrel. Combined hydrodynamics-solid mechanics codes provide transient stresses and strains and final deformations for components such as the reactor vessel, reactor cover, cover holddown bolts, as well as the pulses for which the primary piping system is to be analyzed. Both, Lagrangian and Eulerian two-dimensional codes are under development, which provide greater accuracy and longer durations for the treatment of HCDA. The codes are being augmented with bubble migration capability pertaining to the latter stages of the HCDA, after slug impact. Recent developments involve the adaptation of the 2-D Eulerian primary system code to the 2-D elastic-plastic treatment of primary piping. Pulses are provided at the vessel-primary piping interfaces of the inlet and outlet nozzles, calculation includes the elbows and pressure drops along the components of the primary piping system. Recent improvements to the primary containment codes include introduction of bending strength in materials, Langrangian mesh regularization techniques, and treatment of energy absorbing materials for the slug impact. Another development involves the combination of a 2-D finite element code for the reactor cover with the hydrodynamic containment code
Dynamical structure of hadron emission sources
Zhao Xi; Zhao Shu Song
2000-01-01
NA22 experimental data of the triplet seagull effects show that the Doppler effects of hadron emission sources exist exactly in hadron- hadron collisions. Every source possesses the same average energy (CMS) approximately. The collective seagull effects can be also explained by the (aQ)/sup nu /K/sub nu / (aQ) distributions (generalized functions). The dynamical structure of a hadron emission source is described by the (aQ)/sup nu /K/sub nu / (aQ) distributions. The anomalous dimensions of the pionic quantum fields are gamma /sub B/(g/sub R/)=-0.045+or-0.012, which control the singularities of the production amplitude in quantum field theory. The mathematical parameter epsilon =4-D (the dimension D of space time) in the Feynman integrals can be replaced by the anomalous gamma /sub B/(g/sub R/) of the quantum fields for the regularization. (-2 gamma /sub B/(g/sub R/) to or from epsilon /2=1/ln( Lambda /sup 2//m /sup 2/) Lambda to infinity ). (26 refs).
Dynamical structure of hadron emission sources
International Nuclear Information System (INIS)
Zhao Xi; Huang Bangrong; Zhao Shusong
2000-01-01
NA22 experimental data of the triplet seagull effects show that the Doppler effects of the hadron emission sources exist exactly in the hadron-hadron collisions. Every source possesses the same average energy (CMS) approximately. The collective seagull effects can be also explained by the (aQ) ν K ν (aQ) distributions (Generalized functions). The dynamical structure of a hadron emission source is described by the (aQ) ν K ν (aQ) distributions. The anomalous dimensions of the pionic quantum fields are γ B (g R ) = - 0.045 +- 0.012, which control the singularities of the production amplitude in quantum field theory. The mathematical parameter ε = 4-D (the dimension D of space time) in the Feynman integrals can be replaced by the anomalous γ B (g R ) of the quantum fields for the regularization. (-2γ B (g R )↔ε/2 1/ln(Λ 2 /m 2 )Λ→∞)
Dynamical structure of linearized GL(4) gravities
International Nuclear Information System (INIS)
Aragone, C.; Restuccia, A.
1978-01-01
The physical content of the three more natural models of GL(4) gravity is analyzed, for the case of weak fields. It is shown that the first model is the linearized version of Yang's one-tensor-field gravity and is a scalar-tensor theory, with its scalar part contained in a symmetric tensor. The second and the third linearized models, which can both be derived from the fourth-order action postulated by Yang, are two-tensor decoupled systems. In both cases one of the tensors is the symmetric weak metric gravity tensor field. the second tensor appearing in these two models, representing the GL(4)-gauge field, is either a linearized symmetric affinity (in the second model) or a linearized but nonsymmetric affinity (for the third model). It is shown that in these last two cases the affinity contains a helicity-3 propagating field. Owing to the presence of helicity-3 fields it is shown that it is better to regard Yang's action as an action for a two-tensor system instead of trying to recover from a pure gravity (one-tensor-field) action. Finally, it is shown what is the dynamical structure of the second and third linearized two-tensor models which can be derived from Yang's action. (author)
Flexible joints in structural and multibody dynamics
Directory of Open Access Journals (Sweden)
O. A. Bauchau
2013-02-01
Full Text Available Flexible joints, sometimes called bushing elements or force elements, are found in all structural and multibody dynamics codes. In their simplest form, flexible joints simply consist of sets of three linear and three torsional springs placed between two nodes of the model. For infinitesimal deformations, the selection of the lumped spring constants is an easy task, which can be based on a numerical simulation of the joint or on experimental measurements. If the joint undergoes finite deformations, identification of its stiffness characteristics is not so simple, specially if the joint is itself a complex system. When finite deformations occur, the definition of deformation measures becomes a critical issue. This paper proposes a family of tensorial deformation measures suitable for elastic bodies of finite dimension. These families are generated by two parameters that can be used to modify the constitutive behavior of the joint, while maintaining the tensorial nature of the deformation measures. Numerical results demonstrate the objectivity of the deformations measures, a feature that is not shared by the deformations measures presently used in the literature. The impact of the choice of the two parameters on the constitutive behavior of the flexible joint is also investigated.
Knottin cyclization: impact on structure and dynamics
Directory of Open Access Journals (Sweden)
Gracy Jérôme
2008-12-01
Full Text Available Abstract Background Present in various species, the knottins (also referred to as inhibitor cystine knots constitute a group of extremely stable miniproteins with a plethora of biological activities. Owing to their small size and their high stability, knottins are considered as excellent leads or scaffolds in drug design. Two knottin families contain macrocyclic compounds, namely the cyclotides and the squash inhibitors. The cyclotide family nearly exclusively contains head-to-tail cyclized members. On the other hand, the squash family predominantly contains linear members. Head-to-tail cyclization is intuitively expected to improve bioactivities by increasing stability and lowering flexibility as well as sensitivity to proteolytic attack. Results In this paper, we report data on solution structure, thermal stability, and flexibility as inferred from NMR experiments and molecular dynamics simulations of a linear squash inhibitor EETI-II, a circular squash inhibitor MCoTI-II, and a linear analog lin-MCoTI. Strikingly, the head-to-tail linker in cyclic MCoTI-II is by far the most flexible region of all three compounds. Moreover, we show that cyclic and linear squash inhibitors do not display large differences in structure or flexibility in standard conditions, raising the question as to why few squash inhibitors have evolved into cyclic compounds. The simulations revealed however that the cyclization increases resistance to high temperatures by limiting structure unfolding. Conclusion In this work, we show that, in contrast to what could have been intuitively expected, cyclization of squash inhibitors does not provide clear stability or flexibility modification. Overall, our results suggest that, for squash inhibitors in standard conditions, the circularization impact might come from incorporation of an additional loop sequence, that can contribute to the miniprotein specificity and affinity, rather than from an increase in conformational rigidity
Suppression pool dynamics. Annual report, 1 July 1976--30 June 1977
International Nuclear Information System (INIS)
Chan, C.K.; Chiou, H.H.; Lee, B.K.C.; Dhir, V.K.; Liu, C.Y.; Catton, I.
1978-02-01
The work performed at UCLA to study the transient thermal-hydraulic phenomena induced by the motion of submerged air and steam bubbles in a boiling water reactor (BWR) pressure suppression pool, following a loss-of-coolant accident is described. The air transients, which include vent clearing, bubble growth, and pool swelling, were investigated by a series of air-water tests. These tests were performed in a cylindrical plexiglas test chamber. Gas was injected downward through different-diameter pipes, placed in the middle of the test chamber, which was filled with water at room temperature
Gradient-based optimization in nonlinear structural dynamics
DEFF Research Database (Denmark)
Dou, Suguang
The intrinsic nonlinearity of mechanical structures can give rise to rich nonlinear dynamics. Recently, nonlinear dynamics of micro-mechanical structures have contributed to developing new Micro-Electro-Mechanical Systems (MEMS), for example, atomic force microscope, passive frequency divider......, frequency stabilization, and disk resonator gyroscope. For advanced design of these structures, it is of considerable value to extend current optimization in linear structural dynamics into nonlinear structural dynamics. In this thesis, we present a framework for modelling, analysis, characterization......, and optimization of nonlinear structural dynamics. In the modelling, nonlinear finite elements are used. In the analysis, nonlinear frequency response and nonlinear normal modes are calculated based on a harmonic balance method with higher-order harmonics. In the characterization, nonlinear modal coupling...
Modal analysis application for dynamic characterization of simple structures
International Nuclear Information System (INIS)
Pastorini, A.J.; Belinco, C.G.
1987-01-01
The knowledge of the dynamic characteristics of a structure helps to foresee the vibrating behaviour under operating conditions. The modal analysis techniques offer a method to perform the dynamic characterization of a studied structure from the vibration modes of such structure. A hammer provided with a loaded cell to excite a wide frequency band and accelerometer and, on the basis of a measurement of the transfer function at different points, various simple structures were given with a dynamic structures analysis (of the type of Fourier's rapidly transformation) and the results were compared with those obtained by other methods. Different fields where these techniques are applied, are also enumerated. (Author)
International Nuclear Information System (INIS)
Lee, Hyun Ah; Kim, Yong Il; Park, Gyung Jin; Kang, Byung Soo; Kim, Joo Sung
2006-01-01
All the loads in the real world are dynamic loads and structural optimization under dynamic loads is very difficult. Thus the dynamic loads are often transformed to static loads by dynamic factors, which are believed equivalent to the dynamic loads. However, due to the difference of load characteristics, there can be considerable differences between the results from static and dynamic analyses. When the natural frequency of a structure is high, the dynamic analysis result is similar to that of static analysis due to the small inertia effect on the behavior of the structure. However, if the natural frequency of the structure is low, the inertia effect should not be ignored. then, the behavior of the dynamic system is different from that of the static system. The difference of the two cases can be explained from the relationship between the homogeneous and the particular solutions of the differential equation that governs the behavior of the structure. Through various examples, the difference between the dynamic analysis and the static analysis are shown. Also dynamic response optimization results are compared with the results with static loads transformed from dynamic loads by dynamic factors, which show the necessity of the design considering dynamic loads
Multipactor suppression by micro-structured gold/silver coatings for space applications
Energy Technology Data Exchange (ETDEWEB)
Nistor, Valentin, E-mail: valentin.nistor@uam.es [Departamento de Fisica Aplicada, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); González, Luis A. [Departamento de Fisica Aplicada, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Aguilera, Lydya; Montero, Isabel [Instituto de Ciencia de Materiales de Madrid (CSIC), Cantoblanco, 28049 Madrid (Spain); Galán, Luis [Departamento de Fisica Aplicada, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Wochner, Ulrich [Tesat Spacecom GmbH and Co. KG,Gerberstr. 49, D-71522 Backnang (Germany); Raboso, David [European Space Agency (ESA), European Space Research and Technology Centre (ESTEC), 2200 AG Noordwijk (Netherlands)
2014-10-01
Highlights: • Total suppression of the multipactor effect was achieved for a specific configuration of a high RF power K{sub u}-band waveguide. • Secondary emission of electrons was decreased by surfaces of high aspect ratio. • Simple techniques were used in the manufacturing of metallic microscopical rough coatings. • Surface analysis of the treatment was performed. • The RF insertion losses were improved with respect to Alodine, the standard coating for space applications. - Abstract: The secondary electron emission (SEE) from materials used in high power RF devices in space is the main trigger and sustaining mechanism of the resonant avalanche electron discharge known as the multipactor effect. It limits the attainable power of those devices. During recent decades, some scientific research has been focused on material properties for obtaining anti-multipactor coatings of low secondary emission yield (SEY). The European Space Agency (ESA) is leading a technological research on a new approach based on surface roughness that might perform as a kind of blackbody or Faraday cage effect. A multilayer coating structure was adopted for fulfilling the stringent requirements of the space. The surface of a standard silver plating was modified by a two-step treatment. First, a wet chemically etching process created a roughness of high aspect ratio, in the scale of microns. Secondly, the surface was coated with a protective 2 μm overlayer of gold, using magnetron sputtering. This anti-multipactor coating has been tested on several types of K{sub u}-band WR75 waveguide transformers and band-pass filters, with excellent results. The multipactor effect was suppressed for two waveguides, even when applying the maximum available power levels. As for the other final four, the increase of multipactor power level was in the range of 4–6 dB. These results were obtained after more than one year of air exposure. In spite of the strong roughness, the insertion losses were
Multipactor suppression by micro-structured gold/silver coatings for space applications
International Nuclear Information System (INIS)
Nistor, Valentin; González, Luis A.; Aguilera, Lydya; Montero, Isabel; Galán, Luis; Wochner, Ulrich; Raboso, David
2014-01-01
Highlights: • Total suppression of the multipactor effect was achieved for a specific configuration of a high RF power K u -band waveguide. • Secondary emission of electrons was decreased by surfaces of high aspect ratio. • Simple techniques were used in the manufacturing of metallic microscopical rough coatings. • Surface analysis of the treatment was performed. • The RF insertion losses were improved with respect to Alodine, the standard coating for space applications. - Abstract: The secondary electron emission (SEE) from materials used in high power RF devices in space is the main trigger and sustaining mechanism of the resonant avalanche electron discharge known as the multipactor effect. It limits the attainable power of those devices. During recent decades, some scientific research has been focused on material properties for obtaining anti-multipactor coatings of low secondary emission yield (SEY). The European Space Agency (ESA) is leading a technological research on a new approach based on surface roughness that might perform as a kind of blackbody or Faraday cage effect. A multilayer coating structure was adopted for fulfilling the stringent requirements of the space. The surface of a standard silver plating was modified by a two-step treatment. First, a wet chemically etching process created a roughness of high aspect ratio, in the scale of microns. Secondly, the surface was coated with a protective 2 μm overlayer of gold, using magnetron sputtering. This anti-multipactor coating has been tested on several types of K u -band WR75 waveguide transformers and band-pass filters, with excellent results. The multipactor effect was suppressed for two waveguides, even when applying the maximum available power levels. As for the other final four, the increase of multipactor power level was in the range of 4–6 dB. These results were obtained after more than one year of air exposure. In spite of the strong roughness, the insertion losses were
International Nuclear Information System (INIS)
Nagasaki, Kazunobu; Takamura, Shuichi; Razzak, Md. Abdur; Uesugi, Yoshihiko; Yoshimura, Yasuo; Cappa, Alvaro
2008-01-01
The dynamics and structure of plasma production are stated by the results of two experiments such as the radio frequency thermal plasmas produced by inductively coupled plasma technique at atmospheric pressure and the second harmonic ECH. The first experiment results explained transition from the electrostatic discharge mode of forming streamer to the induced discharge mode after forming the discharge channel that the streamer connected to in the azimuth direction. The other experiment explained the dynamics which the initial plasma produced at the ECH resonance point spread in the direction of radius. The divergence and transition related to the nonlinear process were observed independently existing the magnetic field or incident power. The experiment devices, conditions, results, and modeling are reported. (S.Y.)
Structure and dynamics of the magnetopause
International Nuclear Information System (INIS)
Wang, Z.
1992-01-01
This thesis addresses several topics concerning the structure and dynamics of the magnetopause. These topics include the role of the magnetopause in global convection, the Kelvin-Helmholtz (K-H) instability, which accounts for momentum transport at the magnetopause, the formation of flux ropes by the tearing and twisting modes and particle diffusion across the magnetopause resulting from the destruction of magnetic surfaces. The author establishs an analytic electric field model for an open magnetosphere and introduce a magnetopause to control the reconnection rate and momentum transport. A realistic magnetospheric configuration is realized by 'stretch transformation'. The role of magnetic nulls in the electric field is approached with a technique for direct calculation of electric fields along field lines. Results indicate that electric fields associated with A-type or B-type nulls are generally singular. Then the author considers kinetic effects on the K-H instability. Contrary to the logical assumption that Landau damping damps the instability, it can instead enhance the growth and increase the spatial extent of the instability because the heating of resonance particles enhances the pressure perturbation. A gravitational analogy is used to determine the effect of curvature on K-H instability and it is found that the critical Richardson number for stability increases from 1/4 for incompressible fluids to 1/2 for compressible fluids. The flux rope, which accounts for flux transfer events (FTE), can be formed by a tearing or twisting mode. The tearing mode is self excited by the free energy associated with the magnetic configuration, while the twisting mode must be externally driven. The shear flow generates the twisting mode and reduces the growth rate of the tearing mode. The flux ropes resulting from the twisting mode closely resemble FTE's which have a longer pitch length than that from tearing mode
Visualizing Structure and Dynamics of Disaccharide Simulations
Energy Technology Data Exchange (ETDEWEB)
Matthews, J. F.; Beckham, G. T.; Himmel, M. E.; Crowley, M. F.
2012-01-01
We examine the effect of several solvent models on the conformational properties and dynamics of disaccharides such as cellobiose and lactose. Significant variation in timescale for large scale conformational transformations are observed. Molecular dynamics simulation provides enough detail to enable insight through visualization of multidimensional data sets. We present a new way to visualize conformational space for disaccharides with Ramachandran plots.
International Nuclear Information System (INIS)
Jing, C.; Konecny, R.; Antipov, S.; Chang, C.; Gold, S. H.; Schoessow, P.; Kanareykin, A.; Gai, W.
2013-01-01
Efforts by a number of institutions to develop a Dielectric-Loaded Accelerating (DLA) structure capable of supporting high gradient acceleration when driven by an external radio frequency source have been ongoing over the past decade. Single surface resonant multipactor has been previously identified as one of the major limitations on the practical application of DLA structures in electron accelerators. In this paper, we report the results of an experiment that demonstrated suppression of multipactor growth in an X-band DLA structure through the use of an applied axial magnetic field. This represents an advance toward the practical use of DLA structures in many accelerator applications
Rassin, E; Muris, P; Schmidt, H; Merckelbach, H
2000-09-01
Research has shown that there are strong similarities in content between the obsessions and compulsions that characterize obsessive-compulsive disorder and nonclinical obsessions and compulsions. However, clinical and nonclinical obsessions and compulsions do differ with respect to characteristics like frequency, intensity, discomfort and elicited resistance. Two separate concepts have been invoked to explain how normal obsessions and compulsions may develop into clinical phenomena. First, it is suggested that thought-action fusion (TAF) contributes to obsessive-compulsive symptoms. Second, thought suppression may intensify obsessive-compulsive symptoms due to its paradoxical effect on intrusive thoughts. Although both phenomena have been found to contribute to obsessive-compulsive symptoms, possible interactions between these two have never been investigated. The current study explored how TAF and thought suppression interact in the development of obsessive-compulsive symptoms. Undergraduate psychology students (N = 173) completed questionnaires pertaining to TAF, thought suppression and obsessive-compulsive symptoms. Covariances between the scores on these questionnaires were analyzed by means of structural equation modeling. Results suggest that TAF triggers thought suppression, while thought suppression, in turn, promotes obsessive-compulsive symptoms.
Guo, Jian; Wei, Zhongchao; Liu, Yuebo; Huang, Aili
2015-02-01
Two amplitude modulation methods, including modified Bessel-like function modulation structure and trapezoid annulus structure, for suppressing sidelobes of optical vortices are studied. In the former approach, we propose that the order of the Bessel-like function can be an additional parameter to modulate diffraction patterns of optical vortices motivated by the idea of conventional annulus structures. Furthermore, new Bessel-like modulation functions are introduced to solve the problem of low diffraction efficiency of the original one. Trapezoid annulus structure is proposed as a compromise structure between the modified Bessel-like modulation structure and the conventional annulus one, and has advantages of both. It is demonstrated that these two approaches can achieve high-quality optical vortices with suppressed sidelobes effectively, and the relative structures behave as more flexible and applicable structures for producing optical vortices with large coverage of topological charges, which suggests great potential in simplifying the structure designing procedure. These reliable and generalized structures for generating high-quality optical vortices will help to promote the development of future optical communication and optical manipulation significantly.
International Nuclear Information System (INIS)
Lin, Huang-Kai; Su, Liang-Yu; Hung, Chia-Chin; Huang, JianJang
2013-01-01
In this work, we explore an indium gallium zinc oxide (IGZO) thin film transistor structure with a vacuum annealed IGZO thin film inserted between the dielectric and typical channel layers. The device demonstrates a better subthreshold swing and field-effect mobility due to the suppression of defects in the channel and the channel/dielectric interface. The hybrid channel structure also exhibits the flexibility of adjusting the threshold voltage. The superior carrier mobility was then verified from the transient response of the inverter circuit constructed by the devices. - Highlights: • Additional in-situ annealed In–Ga–ZnO film was inserted in thin film transistor (TFT). • Traps are suppressed and field effect mobility is improved in the TFT. • An inverter with the device structure has a better transient response
Energy Technology Data Exchange (ETDEWEB)
Lin, Huang-Kai; Su, Liang-Yu; Hung, Chia-Chin [Graduate Institute of Photonics and Optoelectronics, National Taiwan University, 1, Roosevelt Road, Sec. 4, Taipei 106, Taiwan (China); Huang, JianJang, E-mail: jjhuang@cc.ee.ntu.edu.tw [Graduate Institute of Photonics and Optoelectronics, National Taiwan University, 1, Roosevelt Road, Sec. 4, Taipei 106, Taiwan (China); Department of Electrical Engineering, National Taiwan University, 1, Roosevelt Road, Sec. 4, Taipei 106, Taiwan (China)
2013-07-01
In this work, we explore an indium gallium zinc oxide (IGZO) thin film transistor structure with a vacuum annealed IGZO thin film inserted between the dielectric and typical channel layers. The device demonstrates a better subthreshold swing and field-effect mobility due to the suppression of defects in the channel and the channel/dielectric interface. The hybrid channel structure also exhibits the flexibility of adjusting the threshold voltage. The superior carrier mobility was then verified from the transient response of the inverter circuit constructed by the devices. - Highlights: • Additional in-situ annealed In–Ga–ZnO film was inserted in thin film transistor (TFT). • Traps are suppressed and field effect mobility is improved in the TFT. • An inverter with the device structure has a better transient response.
Structures in dynamics finite dimensional deterministic studies
Broer, HW; van Strien, SJ; Takens, F
1991-01-01
The study of non-linear dynamical systems nowadays is an intricate mixture of analysis, geometry, algebra and measure theory and this book takes all aspects into account. Presenting the contents of its authors' graduate courses in non-linear dynamical systems, this volume aims at researchers who wish to be acquainted with the more theoretical and fundamental subjects in non-linear dynamics and is designed to link the popular literature with research papers and monographs. All of the subjects covered in this book are extensively dealt with and presented in a pedagogic
Ergodic Theory, Open Dynamics, and Coherent Structures
Bose, Christopher; Froyland, Gary
2014-01-01
This book is comprised of selected research articles developed from a workshop on Ergodic Theory, Probabilistic Methods and Applications, held in April 2012 at the Banff International Research Station. It contains contributions from world leading experts in ergodic theory, dynamical systems, numerical analysis, fluid dynamics, and networks. The volume will serve as a valuable reference for mathematicians, physicists, engineers, physical oceanographers, atmospheric scientists, biologists, and climate scientists, who currently use, or wish to learn how to use, probabilistic techniques to cope with dynamical models that display open, coherent, or non-equilibrium behavior.
Chaotic Dynamics in Smart Grid and Suppression Scheme via Generalized Fuzzy Hyperbolic Model
Sun, Q.; Wang, Y.; Yang, J.; Qiu, Y.; Zhang, H.
2014-01-01
This paper presents a method to control chaotic behavior of a typical Smart Grid based on generalized fuzzy hyperbolic model (GFHM). As more and more distributed generations (DG) are incorporated into the Smart Grid, the chaotic behavior occurs increasingly. To verify the behavior, a dynamic model
Suppression of dynamic laser speckle signals in multimode fibers of various lengths
Petoukhova, Anna; Cleven, Ester; de Mul, F.F.M.; Steenbergen, Wiendelt
2004-01-01
The effects of fiber coupling and fiber length on photocurrent fluctuations are studied when the light of a laser diode transmitted to and from a dynamic turbid medium by a step-index multimode fiber is studied. When the laser light is coupled asymmetrically, filling only the higher-order modes, the
Model reduction tools for nonlinear structural dynamics
Slaats, P.M.A.; Jongh, de J.; Sauren, A.A.H.J.
1995-01-01
Three mode types are proposed for reducing nonlinear dynamical system equations, resulting from finite element discretizations: tangent modes, modal derivatives, and newly added static modes. Tangent modes are obtained from an eigenvalue problem with a momentary tangent stiffness matrix. Their
Multipactor suppression by micro-structured gold/silver coatings for space applications
Nistor, Valentin; González, Luis A.; Aguilera, Lydya; Montero, Isabel; Galán, Luis; Wochner, Ulrich; Raboso, David
2014-10-01
The secondary electron emission (SEE) from materials used in high power RF devices in space is the main trigger and sustaining mechanism of the resonant avalanche electron discharge known as the multipactor effect. It limits the attainable power of those devices. During recent decades, some scientific research has been focused on material properties for obtaining anti-multipactor coatings of low secondary emission yield (SEY). The European Space Agency (ESA) is leading a technological research on a new approach based on surface roughness that might perform as a kind of blackbody or Faraday cage effect. A multilayer coating structure was adopted for fulfilling the stringent requirements of the space. The surface of a standard silver plating was modified by a two-step treatment. First, a wet chemically etching process created a roughness of high aspect ratio, in the scale of microns. Secondly, the surface was coated with a protective 2 μm overlayer of gold, using magnetron sputtering. This anti-multipactor coating has been tested on several types of Ku-band WR75 waveguide transformers and band-pass filters, with excellent results. The multipactor effect was suppressed for two waveguides, even when applying the maximum available power levels. As for the other final four, the increase of multipactor power level was in the range of 4-6 dB. These results were obtained after more than one year of air exposure. In spite of the strong roughness, the insertion losses were diminished by 25% with respect to the values attained in the tests of the standard anti-multipactor coating, Alodine.
4th International Conference on Structural Nonlinear Dynamics and Diagnosis
2018-01-01
This book presents contributions on the most active lines of recent advanced research in the field of nonlinear mechanics and physics selected from the 4th International Conference on Structural Nonlinear Dynamics and Diagnosis. It includes fifteen chapters by outstanding scientists, covering various aspects of applications, including road tanker dynamics and stability, simulation of abrasive wear, energy harvesting, modeling and analysis of flexoelectric nanoactuator, periodic Fermi–Pasta–Ulam problems, nonlinear stability in Hamiltonian systems, nonlinear dynamics of rotating composites, nonlinear vibrations of a shallow arch, extreme pulse dynamics in mode-locked lasers, localized structures in a photonic crystal fiber resonator, nonlinear stochastic dynamics, linearization of nonlinear resonances, treatment of a linear delay differential equation, and fractional nonlinear damping. It appeals to a wide range of experts in the field of structural nonlinear dynamics and offers researchers and engineers a...
Complex-Dynamic Cosmology and Emergent World Structure
Kirilyuk, Andrei P.
2004-01-01
Universe structure emerges in the unreduced, complex-dynamic interaction process with the simplest initial configuration (two attracting homogeneous fields, quant-ph/9902015). The unreduced interaction analysis gives intrinsically creative cosmology, describing the real, explicitly emerging world structure with dynamic randomness on each scale. Without imposing any postulates or entities, we obtain physically real space, time, elementary particles with their detailed structure and intrinsic p...
Discretization model for nonlinear dynamic analysis of three dimensional structures
International Nuclear Information System (INIS)
Hayashi, Y.
1982-12-01
A discretization model for nonlinear dynamic analysis of three dimensional structures is presented. The discretization is achieved through a three dimensional spring-mass system and the dynamic response obtained by direct integration of the equations of motion using central diferences. First the viability of the model is verified through the analysis of homogeneous linear structures and then its performance in the analysis of structures subjected to impulsive or impact loads, taking into account both geometrical and physical nonlinearities is evaluated. (Author) [pt
Recolonizing wolves and mesopredator suppression of coyotes:impacts on pronghorn population dynamics
Berger, Kim Murray; Conner, Mary M.
2015-01-01
Food web theory predicts that the loss of large carnivores may contribute toelevated predation rates and, hence, declining prey populations, through the process ofmesopredator release. However, opportunities to test predictions of the mesopredator releasehypothesis are rare, and the extent to which changes in predation rates inﬂuence preypopulation dynamics may not be clear due to a lack of demographic information on the preypopulation of interest. We utilized spatial and seasonal heterogenei...
Eddy currents self-tuning dynamic vibration absorber for machine tool chatter suppression
Aguirre , Gorka; Gorostiaga , Mikel; Porchez , Thomas; Munoa , Jokin
2013-01-01
International audience; The current trend in machine tool design aims at stiffer machines with lowerinfluence of friction, leading to faster and more precise machines. However, this is atthe expense of reducing the machine damping, which is mainly produced by friction,and thus increasing the risk of suffering from a self-excited vibration named chatter,which limits the productivity of the process. Dynamic vibration absorbers (DVAs)offer a relatively simple and low cost solution to reduce chat...
International Nuclear Information System (INIS)
Watt, James; Schlezinger, Jennifer J.
2015-01-01
Environmental obesogens are a newly recognized category of endocrine disrupting chemicals that have been implicated in contributing to the rising rates of obesity in the United States. While obesity is typically regarded as an increase in visceral fat, adipocyte accumulation in the bone has been linked to increased fracture risk, lower bone density, and osteoporosis. Exposure to environmental toxicants that activate peroxisome proliferator activated receptor γ (PPARγ), a critical regulator of the balance of differentiation between adipogenesis and osteogenesis, may contribute to the increasing prevalence of osteoporosis. However, induction of adipogenesis and suppression of osteogenesis are separable activities of PPARγ, and ligands may selectively alter these activities. It currently is unknown whether suppression of osteogenesis is a common toxic endpoint of environmental PPARγ ligands. Using a primary mouse bone marrow culture model, we tested the hypothesis that environmental toxicants acting as PPARγ agonists divert the differentiation pathway of bone marrow-derived multipotent mesenchymal stromal cells towards adipogenesis and away from osteogenesis. The toxicants tested included the organotins tributyltin and triphenyltin, a ubiquitous phthalate metabolite (mono-(2-ethylhexyl) phthalate, MEHP), and two brominated flame retardants (tetrabromobisphenol-a, TBBPA, and mono-(2-ethylhexyl) tetrabromophthalate, METBP). All of the compounds activated PPARγ1 and 2. All compounds increased adipogenesis (lipid accumulation, Fabp4 expression) and suppressed osteogenesis (alkaline phosphatase activity, Osx expression) in mouse primary bone marrow cultures, but with different potencies and efficacies. Despite structural dissimilarities, there was a strong negative correlation between efficacies to induce adipogenesis and suppress osteogenesis, with the organotins being distinct in their exceptional ability to suppress osteogenesis. As human exposure to a mixture of
Dynamical load factor of impact loaded shell structures
International Nuclear Information System (INIS)
Hammel, J.
1977-01-01
Dynamical loaded structures can be analysed by spectral representations, which usually lead to an enormous computational effort. If it is possible to find a fitting dynamical load factor, the dynamical problem can be reduced to a statical one. The computation of this statical problem is much simpler. The disadvantage is that the dynamical load factor usually leads to a very rough approximation. In this paper it will be shown, that by combination of these two methods, the approximation of the dynamical load factor can be improved and the consumption of computation time can be enormously reduced. (Auth.)
Fundamental structures of dynamic social networks
DEFF Research Database (Denmark)
Sekara, Vedran; Stopczynski, Arkadiusz; Jørgensen, Sune Lehmann
2016-01-01
Social systems are in a constant state of flux, with dynamics spanning from minute-by-minute changes to patterns present on the timescale of years. Accurate models of social dynamics are important for understanding the spreading of influence or diseases, formation of friendships...... and their interactions in the network of real-world person-to-person proximity measured via Bluetooth, as well as their telecommunication networks, online social media contacts, geolocation, and demographic data. These high-resolution data allow us to observe social groups directly, rendering community detection......, and the productivity of teams. Although there has been much progress on understanding complex networks over the past decade, little is known about the regularities governing the microdynamics of social networks. Here, we explore the dynamic social network of a densely-connected population of ∼1,000 individuals...
THE DYNAMICS OF THE MATRICS STRUCTURE
Directory of Open Access Journals (Sweden)
Dumitru CONSTANTINESCU
2007-01-01
Full Text Available The relationships organization-suppliers-customers have recently known major changes in the structure of services and have made the organization develop its managerial and professional competencies in order to do projects. The qualified organization is the most trust-worthy in the process of doing a project. The participation of an organization in doing projects depends on a multitude of factors. Out of these factors, the structural organization comes forth, as it represents the variable with the most important impact on a project’s quality, costs and lead time. From the organizational point of view, the matrix structure is frequently chosen for projects. The matrix structure generally coexists with the line structure. The two structures are contrastive. The line structure is based on the unity of command principle and is not open to cooperation and dialogue. The matrix structure encourages cooperation and communication, favours conflict, which is considered here a healthy and essential process. The matrix structure and the line structure claim their right to initiative. Conflict and the multidimensional integration of multiple hierarchies can be negotiated through the concept charisma – mediation, sustained by the matrix structure.
Nonlinear structural mechanics theory, dynamical phenomena and modeling
Lacarbonara, Walter
2013-01-01
Nonlinear Structural Mechanics: Theory, Dynamical Phenomena and Modeling offers a concise, coherent presentation of the theoretical framework of nonlinear structural mechanics, computational methods, applications, parametric investigations of nonlinear phenomena and their mechanical interpretation towards design. The theoretical and computational tools that enable the formulation, solution, and interpretation of nonlinear structures are presented in a systematic fashion so as to gradually attain an increasing level of complexity of structural behaviors, under the prevailing assumptions on the geometry of deformation, the constitutive aspects and the loading scenarios. Readers will find a treatment of the foundations of nonlinear structural mechanics towards advanced reduced models, unified with modern computational tools in the framework of the prominent nonlinear structural dynamic phenomena while tackling both the mathematical and applied sciences. Nonlinear Structural Mechanics: Theory, Dynamical Phenomena...
Dynamic Capital Structure: Dynamics, Determinants and Speed of Adjustment
Tamirat, A.S.; Trujillo Barrera, A.A.; Pennings, J.M.E.
2017-01-01
The corporate finance literature has focused on explaining the determinants of firms target capital structure and speed of adjustment using the well-established theories such as pecking order, signaling and trade-off theories. However, less attention has been paid to understanding the financing
Recent Progress in Heliogyro Solar Sail Structural Dynamics
Wilkie, William K.; Warren, Jerry E.; Horta, Lucas G.; Juang, Jer-Nan; Gibbs, Samuel C.; Dowell, E.; Guerrant, Daniel; Lawrence Dale
2014-01-01
Results from recent National Aeronautics and Space Administration (NASA) research on the structural dynamics and control characteristics of heliogyro solar sails are summarized. Specific areas under investigation include coupled nonlinear finite element analysis of heliogyro membrane blade with solar radiation pressure effects, system identification of spinning membrane structures, solarelastic stability analysis of heliogyro solar sails, including stability during blade deployment, and results from small-scale in vacuo dynamics experiments with spinning high-aspect ratio membranes. A low-cost, rideshare payload heliogyro technology demonstration mission concept, used as a mission context for these heliogyro structural dynamics and solarelasticity investigations, is also described.
Energy Technology Data Exchange (ETDEWEB)
Hassani Nia, Iman; Fathipour, Vala; Mohseni, Hooman, E-mail: hmohseni@ece.northwestern.edu [Bio-Inspired Sensors and Optoelectronics Laboratory (BISOL), Department of Electrical Engineering, Northwestern University, Evanston, Illinois 60208 (United States)
2015-08-15
We report the first observation of non-threshold Auger mechanism for a quantum well structure with Type-I band alignment. Excitation-dependent photoluminescence measurements were used to extract the Auger recombination coefficients from 77 K up to room temperature. The results verify the role of interface mediated momentum exchange as well as suppression of Auger recombination for delocalized electron-hole wavefunctions.
Friends and foes : The dynamics of dual social structures
Sytch, M.; Tatarynowicz, A.
2014-01-01
This paper investigates the evolutionary dynamics of a dual social structure encompassing collaboration and conflict among corporate actors. We apply and advance structural balance theory to examine the formation of balanced and unbalanced dyadic and triadic structures, and to explore how these
DSIbin : Identifying dynamic data structures in C/C++ binaries
Rupprecht, Thomas; Chen, Xi; White, David H.; Boockmann, Jan H.; Luttgen, Gerald; Bos, Herbert
2017-01-01
Reverse engineering binary code is notoriously difficult and, especially, understanding a binary's dynamic data structures. Existing data structure analyzers are limited wrt. program comprehension: they do not detect complex structures such as skip lists, or lists running through nodes of different
Dynamic fracture toughness testing of structural steels
International Nuclear Information System (INIS)
Debel, C.P.
1978-01-01
Two candidate test methods aimed at producing materials properties of interest in connection with crack arrest assessments are currently under evaluation. These methods and the significance of the results are described. The quasi-static as well as the dynamic fracture toughness of a plain C-Mn steel in the as-quenched and tempered condition have been examined at temperatures between -115 0 C and the ambient temperature. Wedge-loaded duplex DCB-specimens were used in dynamic tests. The crack extension velocity was measured using a surface deposited grid and a registration circuit based on TTL-electronics. The toughness transition-temperature at quasi-static loading rate is found to be low; but during dynamic crack-extension a substantial shift of the transition-region to higher temperatures is produced, and fast fracture was obtained even at ambient temperature. Even though the dynamic fracture toughness Ksub(ID) increases with temperature, it decreases with increasing crack-extension velocity at a given temperature and the rate of decrease with respect to crack-extension velocity seems to be independent of temperature. Ksub(ID) appears to be insensitive to heat treatments. Test results indicate insufficient load-train stiffness, and problems due to crack branching were encountered. (author)
Full scale dynamic testing of Kozloduy NPP unit 5 structures
International Nuclear Information System (INIS)
Da Rin, E.M.
1999-01-01
As described in this report, the Kozloduy NPP western site has been subjected to low level earthquake-like ground shaking - through appropriately devised underground explosions - and the resulting dynamic response of the NPP reactor Unit 5 important structures appropriately measured and digitally recorded. In-situ free-field response was measured concurrently more than 100 m aside the main structures of interest. The collected experimental data provide reference information on the actual dynamic characteristics of the Kozloduy NPPs main structures, as well as give some useful indications on the dynamic soil-structure interaction effects for the case of low level excitation. Performing the present full-scale dynamic structural testing activities took advantage of the experience gained by ISMES during similar tests, lately performed in Italy and abroad (in particular, at the Paks NPP in 1994). The IAEA promoted dynamic testing of the Kozloduy NPP Unit 5 by means of pertinently designed buried explosion-induced ground motions which has provided a large amount of data on the dynamic structural response of its major structures. In the present report, the conducted investigation is described and the acquired digital data presented. A series of preliminary analyses were undertaken for examining in detail the ground excitation levels that were produced by these weak earthquake simulation experiments, as well as for inferring some structural characteristics and behaviour information from the collected data. These analyses ascertained the high quality of the collected digital data. Presumably due to soil-structure dynamic interaction effects, reduced excitation levels were observed at the reactor building foundation raft level with respect to the concurrent free-field ground motions. measured at a 140 m distance from the reactor building centre. Further more detailed and systematic analyses are worthwhile to be performed for extracting more complete information about the
Invariant molecular-dynamics approach to structural phase transitions
International Nuclear Information System (INIS)
Wentzcovitch, R.M.
1991-01-01
Two fictitious Lagrangians to be used in molecular-dynamics simulations with variable cell shape and suitable to study problems like structural phase transitions are introduced. Because they are invariant with respect to the choice of the simulation cell edges and eliminate symmetry breaking associated with the fictitious part of the dynamics, they improve the physical content of numerical simulations that up to now have been done by using Parrinello-Rahman dynamics
Creating a Test Validated Structural Dynamic Finite Element Model of the X-56A Aircraft
Pak, Chan-Gi; Truong, Samson
2014-01-01
Small modeling errors in the finite element model will eventually induce errors in the structural flexibility and mass, thus propagating into unpredictable errors in the unsteady aerodynamics and the control law design. One of the primary objectives of the Multi Utility Technology Test-bed, X-56A aircraft, is the flight demonstration of active flutter suppression, and therefore in this study, the identification of the primary and secondary modes for the structural model tuning based on the flutter analysis of the X-56A aircraft. The ground vibration test-validated structural dynamic finite element model of the X-56A aircraft is created in this study. The structural dynamic finite element model of the X-56A aircraft is improved using a model tuning tool. In this study, two different weight configurations of the X-56A aircraft have been improved in a single optimization run. Frequency and the cross-orthogonality (mode shape) matrix were the primary focus for improvement, while other properties such as center of gravity location, total weight, and offdiagonal terms of the mass orthogonality matrix were used as constraints. The end result was a more improved and desirable structural dynamic finite element model configuration for the X-56A aircraft. Improved frequencies and mode shapes in this study increased average flutter speeds of the X-56A aircraft by 7.6% compared to the baseline model.
Quantifying and modeling soil structure dynamics
Characterization of soil structure has been a topic of scientific discussions ever since soil structure has been recognized as an important factor affecting soil physical, mechanical, chemical, and biological processes. Beyond semi-quantitative soil morphology classes, it is a challenge to describe ...
From Dynamic Condition Response Structures to Büchi Automata
DEFF Research Database (Denmark)
Mukkamala, Raghava Rao; Hildebrandt, Thomas
2010-01-01
Recently we have presented distributed dynamic condition response structures (DCR structures) as a declarative process model conservatively generalizing labelled event structures to allow for finite specifications of repeated, possibly infinite behavior. The key ideas are to split the causality...... relation of event structures in two dual relations: the condition relation and the response relation, to split the conflict relation in two relations: the dynamic exclusion and dynamic inclusion, and finally to allow configurations to be multi sets of events. In the present abstract we recall the model...... and show how to characterise the execution of DCR structures and the acceptance condition for infinite runs by giving a map to Bu ̈chi-automata. This is the first step towards automatic verification of processes specified as DCR structures....
Dynamical community structure of populations evolving on genotype networks
International Nuclear Information System (INIS)
Capitán, José A.; Aguirre, Jacobo; Manrubia, Susanna
2015-01-01
Neutral evolutionary dynamics of replicators occurs on large and heterogeneous networks of genotypes. These networks, formed by all genotypes that yield the same phenotype, have a complex architecture that conditions the molecular composition of populations and their movements on genome spaces. Here we consider as an example the case of populations evolving on RNA secondary structure neutral networks and study the community structure of the network revealed through dynamical properties of the population at equilibrium and during adaptive transients. We unveil a rich hierarchical community structure that, eventually, can be traced back to the non-trivial relationship between RNA secondary structure and sequence composition. We demonstrate that usual measures of modularity that only take into account the static, topological structure of networks, cannot identify the community structure disclosed by population dynamics
Evers, Jochem B.; Bastiaans, Lammert
2016-01-01
Suppression of weed growth in a crop canopy can be enhanced by improving crop competitiveness. One way to achieve this is by modifying the crop planting pattern. In this study, we addressed the question to what extent a uniform planting pattern increases the ability of a crop to compete with weed
Dynamic analysis of CHASNUPP steam generator structure during shipping
International Nuclear Information System (INIS)
Han Liangbi; Xu Jinkang; Zhou Meiwu; He Yinbiao
1998-07-01
The dynamic analysis of CHASNUPP steam generator during shipping is described, including the simplified mathematical model, acceleration power spectrum of ocean wave induced random vibration, the dynamic analysis of steam generator structure under random loading, the applied computer code and calculated results
Crystal structure and pair potentials: A molecular-dynamics study
Energy Technology Data Exchange (ETDEWEB)
Parrinello, M.; Rahman, A.
1980-10-06
With use of a Lagrangian which allows for the variation of the shape and size of the periodically repeating molecular-dynamics cell, it is shown that different pair potentials lead to different crystal structures.
Simulation of Protein Structure, Dynamics and Function in Organic Media
National Research Council Canada - National Science Library
Daggett, Valerie
1998-01-01
The overall goal of our ONR-sponsored research is to pursue realistic molecular modeling strudies pertinnent to the related properties of protein stability, dynamics, structure, function, and folding in aqueous solution...
VanZwieten, Tannen S.; Gilligan, Eric T.; Wall, John H.; Miller, Christopher J.; Hanson, Curtis E.; Orr, Jeb S.
2015-01-01
NASA's Space Launch System (SLS) Flight Control System (FCS) includes an Adaptive Augmenting Control (AAC) component which employs a multiplicative gain update law to enhance the performance and robustness of the baseline control system for extreme off-nominal scenarios. The SLS FCS algorithm including AAC has been flight tested utilizing a specially outfitted F/A-18 fighter jet in which the pitch axis control of the aircraft was performed by a Non-linear Dynamic Inversion (NDI) controller, SLS reference models, and the SLS flight software prototype. This paper describes test cases from the research flight campaign in which the fundamental F/A-18 airframe structural mode was identified using post-flight frequency-domain reconstruction, amplified to result in closed loop instability, and suppressed in-flight by the SLS adaptive control system.
Wall, John H.; VanZwieten, Tannen S.; Gilligan, Eric T.; Miller, Christopher J.; Hanson, Curtis E.; Orr, Jeb S.
2015-01-01
NASA's Space Launch System (SLS) Flight Control System (FCS) includes an Adaptive Augmenting Control (AAC) component which employs a multiplicative gain update law to enhance the performance and robustness of the baseline control system for extreme off nominal scenarios. The SLS FCS algorithm including AAC has been flight tested utilizing a specially outfitted F/A-18 fighter jet in which the pitch axis control of the aircraft was performed by a Non-linear Dynamic Inversion (NDI) controller, SLS reference models, and the SLS flight software prototype. This paper describes test cases from the research flight campaign in which the fundamental F/A-18 airframe structural mode was identified using frequency-domain reconstruction of flight data, amplified to result in closed loop instability, and suppressed in-flight by the SLS adaptive control system.
Limitations and corrections in measuring dynamic characteristics of structural systems
International Nuclear Information System (INIS)
Walter, P.L.
1978-10-01
The work deals with limitations encountered in measuring the dynamic characteristics of structural systems. Structural loading and response are measured by transducers possessing multiple resonant frequencies in their transfer function. In transient environments, the resultant signals from these transducers are shown to be analytically unpredictable in amplitude level and frequency content. Data recorded during nuclear effects simulation testing on structures are analyzed. Results of analysis can be generalized to any structure which encounters dynamic loading. Methods to improve the recorded data are described which can be implemented on a frequency selective basis during the measurement process. These improvements minimize data distortion attributable to the transfer characteristics of the measuring transducers
THE DYNAMICS OF THE MATRICS STRUCTURE
Dumitru CONSTANTINESCU
2007-01-01
The relationships organization-suppliers-customers have recently known major changes in the structure of services and have made the organization develop its managerial and professional competencies in order to do projects. The qualified organization is the most trust-worthy in the process of doing a project. The participation of an organization in doing projects depends on a multitude of factors. Out of these factors, the structural organization comes forth, as it represents the variable with...
Suppression of dynamic stall with a leading-edge slat on a VR-7 airfoil
Mcalister, K. W.; Tung, C.
1993-01-01
The VR-7 airfoil was experimentally studied with and without a leading-edge slat at fixed angles of attack from 0 deg to 30 deg at Re = 200,000 and for unsteady pitching motions described by alpha equals alpha(sub m) + 10 deg(sin(wt)). The models were two dimensional, and the test was performed in a water tunnel at Ames Research Center. The unsteady conditions ranged over Re equals 100,000 to 250,000, k equals 0.001 to 0.2, and alpha(sub m) = 10 deg to 20 deg. Unsteady lift, drag, and pitching-moment measurements were obtained along with fluorescent-dye flow visualizations. The addition of the slat was found to delay the static-drag and static-moment stall by about 5 degrees and to eliminate completely the development of a dynamic-stall vortex during unsteady motions that reached angles as high as 25 degrees. In all of the unsteady cases studied, the slat caused a significant reduction in the force and moment hysteresis amplitudes. The reduced frequency was found to have the greatest effect on the results, whereas the Reynolds number had little effect on the behavior of either the basic or the slatted airfoil. The slat caused a slight drag penalty at low angles of attack, but generally increased the lift/drag ratio when averaged over the full cycle of oscillation.
Directory of Open Access Journals (Sweden)
Xiaohui Zeng
2016-03-01
Full Text Available Dual-chamber air springs are used as a key component for vibration isolation in some industrial applications. The working principle of the dual-chamber air spring device as applied to motion suppression of marine structures is similar to that of the traditional air spring, but they differ in their specific characteristics. The stiffness and damping of the dual-chamber air spring device determine the extent of motion suppression. In this article, we investigate the stiffness and damping characteristics of a dual-chamber air spring device applied to marine structure motion suppression using orthogonal analysis and an experimental method. We measure the effects of volume ratio, orifice ratio, excitation amplitude, and frequency on the stiffness and damping of the dual-chamber vibration absorber. Based on the experimental results, a higher-order non-linear regression method is obtained. We achieve a rapid calculation model for dual-chamber air spring stiffness and damping, which can provide guidance to project design.
Dynamical stability in fluid-structure interaction
International Nuclear Information System (INIS)
Planchard, J.; Thomas, B.
1991-01-01
The aim of the paper is to investigate the dynamical stability of a group of elastic tubes placed in a cross-flow which obeys to the Navier-Stokes equations. The stability of this coupled system is deduced from the study of a quadratic eigenvalue problem arising in the linearized equations. The instability occurs when the real part of one of the eigenvalues becomes positive; the steady state is then replaced by a time-periodic state which is stable (Hopf bifurcation phenomenon). Some numerical methods for solving the quadratic eigenvalue problem are described [fr
Atomic probes of surface structure and dynamics
International Nuclear Information System (INIS)
Heller, E.J.; Jonsson, H.
1992-01-01
Progress for the period Sept. 15, 1992 to Sept. 14, 1993 is discussed. Semiclassical methods that will allow much faster and more accurate three-dimensional atom--surface scattering calculations, both elastic and inelastic, are being developed. The scattering of He atoms from buckyballs is being investigated as a test problem. Somewhat more detail is given on studies of He atom scattering from defective Pt surfaces. Molecular dynamics simulations of He + and Ar + ion sputtering of Pt surfaces are also being done. He atom scattering from Xe overlayers on metal surfaces and the thermalized dissociation of H 2 on Cu(110) are being studied. (R.W.R.) 64 refs
Dynamics of structures '89. Vol. 3
International Nuclear Information System (INIS)
1989-01-01
The proceedings, comprising 3 volumes published by the Plzen Centre of the Czechoslovak Society for Science and Technology (Vol. 1 and 2) and by Skoda Works in Plzen (Vol. 3), contain 107 papers, out of which 8 fall within the INIS Subject Scope; these deal with problems related to the earthquake resistance of nuclear power plants. Attention is paid to the evaluation of seismic characteristics of nuclear power plant equipment, to the equipment testing and to calculations of its dynamic characteristics under simulated seismic stress. (Z.M.)
Dynamic isoperimetry and the geometry of Lagrangian coherent structures
International Nuclear Information System (INIS)
Froyland, Gary
2015-01-01
The study of transport and mixing processes in dynamical systems is particularly important for the analysis of mathematical models of physical systems. We propose a novel, direct geometric method to identify subsets of phase space that remain strongly coherent over a finite time duration. This new method is based on a dynamic extension of classical (static) isoperimetric problems; the latter are concerned with identifying submanifolds with the smallest boundary size relative to their volume.The present work introduces dynamic isoperimetric problems; the study of sets with small boundary size relative to volume as they are evolved by a general dynamical system. We formulate and prove dynamic versions of the fundamental (static) isoperimetric (in)equalities; a dynamic Federer–Fleming theorem and a dynamic Cheeger inequality. We introduce a new dynamic Laplace operator and describe a computational method to identify coherent sets based on eigenfunctions of the dynamic Laplacian.Our results include formal mathematical statements concerning geometric properties of finite-time coherent sets, whose boundaries can be regarded as Lagrangian coherent structures. The computational advantages of our new approach are a well-separated spectrum for the dynamic Laplacian, and flexibility in appropriate numerical approximation methods. Finally, we demonstrate that the dynamic Laplace operator can be realised as a zero-diffusion limit of a newly advanced probabilistic transfer operator method [9] for finding coherent sets, which is based on small diffusion. Thus, the present approach sits naturally alongside the probabilistic approach [9], and adds a formal geometric interpretation. (paper)
Cardiolipin effects on membrane structure and dynamics.
Unsay, Joseph D; Cosentino, Katia; Subburaj, Yamunadevi; García-Sáez, Ana J
2013-12-23
Cardiolipin (CL) is a lipid with unique properties solely found in membranes generating electrochemical potential. It contains four acyl chains and tends to form nonlamellar structures, which are believed to play a key role in membrane structure and function. Indeed, CL alterations have been linked to disorders such as Barth syndrome and Parkinson's disease. However, the molecular effects of CL on membrane organization remain poorly understood. Here, we investigated the structure and physical properties of CL-containing membranes using confocal microscopy, fluorescence correlation spectroscopy, and atomic force microscopy. We found that the fluidity of the lipid bilayer increased and its mechanical stability decreased with CL concentration, indicating that CL decreases the packing of the membrane. Although the presence of up to 20% CL gave rise to flat, stable bilayers, the inclusion of 5% CL promoted the formation of flowerlike domains that grew with time. Surprisingly, we often observed two membrane-piercing events in atomic force spectroscopy experiments with CL-containing membranes. Similar behavior was observed with a lipid mixture mimicking the mitochondrial outer membrane composition. This suggests that CL promotes the formation of membrane areas with apposed double bilayers or nonlamellar structures, similar to those proposed for mitochondrial contact sites. All together, we show that CL induces membrane alterations that support the role of CL in facilitating bilayer structure remodeling, deformation, and permeabilization.
Chaos, dynamical structure and climate variability
Energy Technology Data Exchange (ETDEWEB)
Stewart, H.B. [Brookhaven National Lab., Upton, NY (United States). Dept. of Applied Science
1995-09-01
Deterministic chaos in dynamical systems offers a new paradigm for understanding irregular fluctuations. Techniques for identifying deterministic chaos from observed data, without recourse to mathematical models, are being developed. Powerful methods exist for reconstructing multidimensional phase space from an observed time series of a single scalar variable; these methods are invaluable when only a single scalar record of the dynamics is available. However, in some applications multiple concurrent time series may be available for consideration as phase space coordinates. Here the authors propose some basic analytical tools for such multichannel time series data, and illustrate them by applications to a simple synthetic model of chaos, to a low-order model of atmospheric circulation, and to two high-resolution paleoclimate proxy data series. The atmospheric circulation model, originally proposed by Lorenz, has 27 principal unknowns; they establish that the chaotic attractor can be embedded in a subspace of eight dimensions by exhibiting a specific subset of eight unknowns which pass multichannel tests for false nearest neighbors. They also show that one of the principal unknowns in the 27-variable model--the global mean sea surface temperature--is of no discernible usefulness in making short-term forecasts.
Nonlinear and stochastic dynamics of coherent structures
DEFF Research Database (Denmark)
Rasmussen, Kim
1997-01-01
This Thesis deals with nonlinear and stochastic dynamics in systems which can be described by nonlinear Schrödinger models. Basically three different models are investigated. The first is the continuum nonlinear Schröndinger model in one and two dimensions generalized by a tunable degree of nonli......This Thesis deals with nonlinear and stochastic dynamics in systems which can be described by nonlinear Schrödinger models. Basically three different models are investigated. The first is the continuum nonlinear Schröndinger model in one and two dimensions generalized by a tunable degree...... introduces the nonlinear Schrödinger model in one and two dimensions, discussing the soliton solutions in one dimension and the collapse phenomenon in two dimensions. Also various analytical methods are described. Then a derivation of the nonlinear Schrödinger equation is given, based on a Davydov like...... system described by a tight-binding Hamiltonian and a harmonic lattice coupled b y a deformation-type potential. This derivation results in a two-dimensional nonline ar Schrödinger model, and considering the harmonic lattice to be in thermal contact with a heat bath w e show that the nonlinear...
Hadron structure with light dynamical quarks
International Nuclear Information System (INIS)
Edwards, R.G.; Richards, D.G.; Fleming, G.T.; Haegler, P.; Negele, J.W.; Orginos, K.; Pochinsky, A.; Renner, D.B.; Schroers, W.
2005-09-01
Generalized parton distributions encompass a wealth of information concerning the three-dimensional quark and gluon structure of the nucleon, and thus provide an ideal focus for the study of hadron structure using lattice QCD. The special limits corresponding to form factors and parton distributions are well explored experimentally, providing clear tests of lattice calculations, and the lack of experimental data for more general cases provides opportunities for genuine predictions and for guiding experiment. We present results from hybrid calculations with improved staggered (Asqtad) sea quarks and domain wall valence quarks at pion masses down to 350 MeV. (orig.)
Limitation and suppression of hot electron fluctuations in submicron semiconductor structures
International Nuclear Information System (INIS)
Kochelap, V.A.; Zahleniuk, N.A.; Sokolov, V.N.
1992-09-01
We present theoretical investigations of fluctuations of hot electrons in submicron active regions, where the dimensions 2 d of the region is comparable to the electron energy relaxation length L ε . The new physical phenomenon is reported; the fluctuations depend on the sample thickness, with 2d ε a suppression of fluctuations arises in the range of fluctuation frequencies ω much less than T -1 ε , T ε is the electron energy relaxation time. (author). 12 refs, 7 figs
A framework of DYNAMIC data structures for string processing
DEFF Research Database (Denmark)
Prezza, Nicola
2017-01-01
implemented using DYNAMIC with those of stateof-the-art tools performing the same task. Our experiments show that algorithms making use of dynamic compressed data structures can be up to three orders of magnitude more space-efficient (albeit slower) than classical ones performing the same tasks.......In this paper we present DYNAMIC, an open-source C++ library implementing dynamic compressed data structures for string manipulation. Our framework includes useful tools such as searchable partial sums, succinct/gap-encoded bitvectors, and entropy/run-length compressed strings and FM indexes. We...... prove close-to-optimal theoretical bounds for the resources used by our structures, and show that our theoretical predictions are empirically tightly verified in practice. To conclude, we turn our attention to applications. We compare the performance of five recently-published compression algorithms...
Mid-frequency Band Dynamics of Large Space Structures
Coppolino, Robert N.; Adams, Douglas S.
2004-01-01
High and low intensity dynamic environments experienced by a spacecraft during launch and on-orbit operations, respectively, induce structural loads and motions, which are difficult to reliably predict. Structural dynamics in low- and mid-frequency bands are sensitive to component interface uncertainty and non-linearity as evidenced in laboratory testing and flight operations. Analytical tools for prediction of linear system response are not necessarily adequate for reliable prediction of mid-frequency band dynamics and analysis of measured laboratory and flight data. A new MATLAB toolbox, designed to address the key challenges of mid-frequency band dynamics, is introduced in this paper. Finite-element models of major subassemblies are defined following rational frequency-wavelength guidelines. For computational efficiency, these subassemblies are described as linear, component mode models. The complete structural system model is composed of component mode subassemblies and linear or non-linear joint descriptions. Computation and display of structural dynamic responses are accomplished employing well-established, stable numerical methods, modern signal processing procedures and descriptive graphical tools. Parametric sensitivity and Monte-Carlo based system identification tools are used to reconcile models with experimental data and investigate the effects of uncertainties. Models and dynamic responses are exported for employment in applications, such as detailed structural integrity and mechanical-optical-control performance analyses.
Fonda, James; Rao, Vittal S.; Sana, Sridhar
2001-08-01
This paper provides an account of a student research project conducted under the sponsoring of the National Science Foundation (NSF) program on Research Experience for Undergraduates (REU) in Mechatronics and Smart Strictures in the summer of 2000. The objective of the research is to design and test a stand-alone controller for a vibration isolation/suppression system. The design specification for the control system is to suppress the vibrations induced by the external disturbances by at least fiver times and hence to achieve vibration isolation. Piezo-electric sensors and actuators are utilized for suppression of unwanted vibrations. Various steps such as modeling of the system, controller design, simulation, closed-loop testing using d- Space rapid prototyping system, and analog control implementation are discussed in the paper. Procedures for data collection, the trade-offs carried out in the design, and analog controller implementation issues are also presented in the paper. The performances of various controllers are compared. The experiences of an undergraduate student are summarized in the conclusion of the paper.
Structural Identifiability of Dynamic Systems Biology Models.
Villaverde, Alejandro F; Barreiro, Antonio; Papachristodoulou, Antonis
2016-10-01
A powerful way of gaining insight into biological systems is by creating a nonlinear differential equation model, which usually contains many unknown parameters. Such a model is called structurally identifiable if it is possible to determine the values of its parameters from measurements of the model outputs. Structural identifiability is a prerequisite for parameter estimation, and should be assessed before exploiting a model. However, this analysis is seldom performed due to the high computational cost involved in the necessary symbolic calculations, which quickly becomes prohibitive as the problem size increases. In this paper we show how to analyse the structural identifiability of a very general class of nonlinear models by extending methods originally developed for studying observability. We present results about models whose identifiability had not been previously determined, report unidentifiabilities that had not been found before, and show how to modify those unidentifiable models to make them identifiable. This method helps prevent problems caused by lack of identifiability analysis, which can compromise the success of tasks such as experiment design, parameter estimation, and model-based optimization. The procedure is called STRIKE-GOLDD (STRuctural Identifiability taKen as Extended-Generalized Observability with Lie Derivatives and Decomposition), and it is implemented in a MATLAB toolbox which is available as open source software. The broad applicability of this approach facilitates the analysis of the increasingly complex models used in systems biology and other areas.
Oxide Interfaces: emergent structure and dynamics
Energy Technology Data Exchange (ETDEWEB)
Clarke, Roy [Univ. of Michigan, Ann Arbor, MI (United States)
2016-08-16
This Final Report describes the scientific accomplishments that have been achieved with support from grant DE-FG02-06ER46273 during the period 6/1/2012– 5/31/2016. The overall goals of this program were focused on the behavior of epitaxial oxide heterostructures at atomic length scales (Ångstroms), and correspondingly short time-scales (fs -ns). The results contributed fundamentally to one of the currently most active frontiers in condensed matter physics research, namely to better understand the intricate relationship between charge, lattice, orbital and spin degrees of freedom that are exhibited by complex oxide heterostructures. The findings also contributed towards an important technological goal which was to achieve a better basic understanding of structural and electronic correlations so that the unusual properties of complex oxides can be exploited for energy-critical applications. Specific research directions included: probing the microscopic behavior of epitaxial interfaces and buried layers; novel materials structures that emerge from ionic and electronic reconfiguration at epitaxial interfaces; ultrahigh-resolution mapping of the atomic structure of heterointerfaces using synchrotron-based x-ray surface scattering, including direct methods of phase retrieval; using ultrafast lasers to study the effects of transient strain on coherent manipulation of multi-ferroic order parameters; and investigating structural ordering and relaxation processes in real-time.
Structure and dynamics of magnetic nanoparticles
DEFF Research Database (Denmark)
Clausen, K.N.; Bødker, F.; Hansen, M.F.
2000-01-01
In this paper we present X-ray and neutron diffraction data illustrating aspects of crystal and magnetic structures of ferromagnetic alpha-Fe and antiferromagnetic NiO nanoparticles, as well as inelastic neutron scattering studies of the magnetic fluctuations in NiO and in canted antiferromagnetic...
Emergence of structured communities through evolutionary dynamics.
Shtilerman, Elad; Kessler, David A; Shnerb, Nadav M
2015-10-21
Species-rich communities, in which many competing species coexist in a single trophic level, are quite frequent in nature, but pose a formidable theoretical challenge. In particular, it is known that complex competitive systems become unstable and unfeasible when the number of species is large. Recently, many studies have attributed the stability of natural communities to the structure of the interspecific interaction network, yet the nature of such structures and the underlying mechanisms responsible for them remain open questions. Here we introduce an evolutionary model, based on the generic Lotka-Volterra competitive framework, from which a stable, structured, diverse community emerges spontaneously. The modular structure of the competition matrix reflects the phylogeny of the community, in agreement with the hierarchial taxonomic classification. Closely related species tend to have stronger niche overlap and weaker fitness differences, as opposed to pairs of species from different modules. The competitive-relatedness hypothesis and the idea of emergent neutrality are discussed in the context of this evolutionary model. Copyright © 2015 Elsevier Ltd. All rights reserved.
Dynamic structure in self-sustained turbulence
International Nuclear Information System (INIS)
Itoh, K.; Itoh, S.; Yagi, M.; Fukuyama, A.
1995-06-01
Dynamical equation for the self-sustained and pressure-driven turbulence in toroidal plasmas is derived. The growth rate of the dressed-test mode, which belongs to the subcritical turbulence, is obtained as a function of the turbulent transport coefficient. In the limit of the low fluctuation level, the mode has the feature of the nonlinear instability and shows the explosive growth. The growth rate vanishes when the driven transport reaches to the stationarily-turbulent level. The stationary solution is thermodynamically stable. The characteristic time, by which the stationary and self-sustained turbulence is established, scales with the ion-sound transit time and is accelerated by the bad magnetic curvature. Influences of the pressure gradient as well as the radial electric field inhomogeneity are quantified. (author)
Structure an dynamics in cavity quantum electrodynamics
International Nuclear Information System (INIS)
Kimble, H.J.
1994-01-01
Much of the theoretical background related to the radiative processes for atoms in the presence of boundaries comes from two often disjoint areas, namely cavity quantum electrodynamics and optical bistability with two-state atoms. While the former of these areas has been associated to a large degree with studies in a perturbative domain of altered associated to a large degree with studies in a perturbative domain of altered emission processes in the presence of boundaries other than those of free space, the latter is often viewed from the perspective of hysteresis cycles and device applications. With the exception of the laser, however, perhaps the most extensive investigations of quantum statistical processes in quantum optics are to be found in the literature on bistability with two-state atoms and on cavity QED. Unfortunately, the degree of overlap of these two areas has not always been fully appreciated. This circumstance is perhaps due in part to the fact that the investigation of dynamical processes in cavity QED has had as its cornerstone the Jaynes-Cummings problem, with extensions to include, for example, small amounts of dissipation. On the other hand, a principle aspect of the bistability literature has been the study of quantum fluctuations in open systems for which dissipation plays a central role, but for which the coherent quantum dynamics of the Haynes-Cummings model are to a large measure lost due to the usual assumption of large system size and weak coupling (as in the standard theory of the laser). 132 refs., 26 figs., 1 tab
Directory of Open Access Journals (Sweden)
Kyle M Hocking
Full Text Available Initiation of force generation during vascular smooth muscle contraction involves a rise in intracellular calcium ([Ca(2+]i and phosphorylation of myosin light chains (MLC. However, reversal of these two processes alone does not account for the force inhibition that occurs during relaxation or inhibition of contraction, implicating that other mechanisms, such as actin cytoskeletal rearrangement, play a role in the suppression of force. In this study, we hypothesize that forskolin-induced force suppression is dependent upon changes in actin cytoskeletal dynamics. To focus on the actin cytoskeletal changes, a physiological model was developed in which forskolin treatment of intact porcine coronary arteries (PCA prior to treatment with a contractile agonist resulted in complete suppression of force. Pretreatment of PCA with forskolin suppressed histamine-induced force generation but did not abolish [Ca(2+]i rise or MLC phosphorylation. Additionally, forskolin pretreatment reduced filamentous actin in histamine-treated tissues, and prevented histamine-induced changes in the phosphorylation of the actin-regulatory proteins HSP20, VASP, cofilin, and paxillin. Taken together, these results suggest that forskolin-induced complete force suppression is dependent upon the actin cytoskeletal regulation initiated by the phosphorylation changes of the actin regulatory proteins and not on the MLC dephosphorylation. This model of complete force suppression can be employed to further elucidate the mechanisms responsible for smooth muscle tone, and may offer cues to pathological situations, such as hypertension and vasospasm.
Dynamic loads during failure risk assessment of bridge crane structures
Gorynin, A. D.; Antsev, V. Yu; Shaforost, A. N.
2018-03-01
The paper presents the method of failure risk assessment associated with a bridge crane metal structure at the design stage. It also justifies the necessity of taking into account dynamic loads with regard to the operational cycle of a bridge crane during failure risk assessment of its metal structure.
Molecular dynamics of the structure and thermodynamics of dusty ...
African Journals Online (AJOL)
The static structure and thermodynamic properties of two-dimensional dusty plasma are analyzed for some typical values of coupling and screening parameters using classical molecular dynamics. Radial distribution function and static structure factor are computed. The radial distribution functions display the typical ...
Molecular dynamic analysis of the structure of dendrimers
Energy Technology Data Exchange (ETDEWEB)
Canetta, E.; Maino, G. E-mail: maino@bologna.enea.it
2004-01-01
We present main results of molecular dynamics simulations that we have carried out in order to investigate structural properties of polyamidoamine (PAMAM) dendrimers. Obtained data confirm the PAMAM dendrimer structure proposed by experiments, performed by means of X-ray scattering (SAXS) and quasi-elastic light scattering (QELS) techniques.
Molecular dynamic analysis of the structure of dendrimers
International Nuclear Information System (INIS)
Canetta, E.; Maino, G.
2004-01-01
We present main results of molecular dynamics simulations that we have carried out in order to investigate structural properties of polyamidoamine (PAMAM) dendrimers. Obtained data confirm the PAMAM dendrimer structure proposed by experiments, performed by means of X-ray scattering (SAXS) and quasi-elastic light scattering (QELS) techniques
Li, Ronghua; Boudot, Mickael; Boissière, Cédric; Grosso, David; Faustini, Marco
2017-04-26
The appearance of structural colors on coated-glass is a critical esthetical drawback toward industrialization of photocatalytic coatings on windows for architecture or automobile. Herein we describe a rational approach to suppress the structural color of mesoporous TiO 2 -based coatings preserving photoactivity and mechanical stiffness. Addition of SiO 2 as third component is discussed. Ti x Si (1-x) O 2 mesoporous coatings were fabricated by one-step liquid deposition process through the evaporation induced self-assembling and characterized by GI-SAXS, GI-WAXS, electron microscopies, and in situ Environmental Ellipsometry Porosimetry. Guided by optical simulation, we investigated the critical role of SiO 2 on the optical responses of the films but also on the structural, mechanical, and photocatalytic properties, important requirements to go toward real applications. We demonstrate that adding SiO 2 to porous TiO 2 allows tuning and suppression of structural colors through refractive index matching and up to 160% increase in mechanical stiffening of the films. This study leads us to demonstrate an example of "invisible" coating, in which the light reflection is angle- and thickness-independent, and exhibiting high porosity, mechanical stiffness, and photoactivity.
Dynamic kirigami structures for integrated solar tracking
Lamoureux, Aaron; Lee, Kyusang; Shlian, Matthew; Forrest, Stephen R.; Shtein, Max
2015-01-01
Optical tracking is often combined with conventional flat panel solar cells to maximize electrical power generation over the course of a day. However, conventional trackers are complex and often require costly and cumbersome structural components to support system weight. Here we use kirigami (the art of paper cutting) to realize novel solar cells where tracking is integral to the structure at the substrate level. Specifically, an elegant cut pattern is made in thin-film gallium arsenide solar cells, which are then stretched to produce an array of tilted surface elements which can be controlled to within ±1°. We analyze the combined optical and mechanical properties of the tracking system, and demonstrate a mechanically robust system with optical tracking efficiencies matching conventional trackers. This design suggests a pathway towards enabling new applications for solar tracking, as well as inspiring a broader range of optoelectronic and mechanical devices. PMID:26348820
Structure and dynamics of ringed galaxies
International Nuclear Information System (INIS)
Buta, R.J.
1984-01-01
In many spiral and SO galaxies, single or multiple ring structures are visible in the disk. These inner rings (r), outer rings (R), and nuclear rings (nr) were investigated by means of morphology, photometry, and spectroscopy in order to provide basic data on a long neglected phenomenon. The metric properties of each ring are investigated and found to correlate with the structure of the parent galaxy. When properly calibrated, inner rings in barred (SB) systems can be used as geometric extragalactic distance indicators to distances in excess of 100 Mpc. Other statistics are presented that confirm previous indications that the rings have preferred shapes, relative sizes, and orientations with respect to bars. A survey is made of the less homogeneous non-barred (SA) ringed systems, and the causes of the inhomogeneity are isolated. It is shown that rings can be identified in multiple-ring SA systems that are exactly analogous to those in barred spirals
International Conference on Structural Nonlinear Dynamics and Diagnosis
CSNDD 2012; CSNDD 2014
2015-01-01
This book, which presents the peer-reviewed post-proceedings of CSNDD 2012 and CSNDD 2014, addresses the important role that relevant concepts and tools from nonlinear and complex dynamics could play in present and future engineering applications. It includes 22 chapters contributed by outstanding researchers and covering various aspects of applications, including: structural health monitoring, diagnosis and damage detection, experimental methodologies, active vibration control and smart structures, passive control of structures using nonlinear energy sinks, vibro-impact dynamic MEMS/NEMS/AFM, energy-harvesting materials and structures, and time-delayed feedback control, as well as aspects of deterministic versus stochastic dynamics and control of nonlinear phenomena in physics. Researchers and engineers interested in the challenges posed and opportunities offered by nonlinearities in the development of passive and active control strategies, energy harvesting, novel design criteria, modeling and characteriz...
Structural dynamics of the cell nucleus
Wiegert, Simon; Bading, Hilmar
2011-01-01
Neuronal morphology plays an essential role in signal processing in the brain. Individual neurons can undergo use-dependent changes in their shape and connectivity, which affects how intracellular processes are regulated and how signals are transferred from one cell to another in a neuronal network. Calcium is one of the most important intracellular second messengers regulating cellular morphologies and functions. In neurons, intracellular calcium levels are controlled by ion channels in the plasma membrane such as NMDA receptors (NMDARs), voltage-gated calcium channels (VGCCs) and certain α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) as well as by calcium exchange pathways between the cytosol and internal calcium stores including the endoplasmic reticulum and mitochondria. Synaptic activity and the subsequent opening of ligand and/or voltage-gated calcium channels can initiate cytosolic calcium transients which propagate towards the cell soma and enter the nucleus via its nuclear pore complexes (NPCs) embedded in the nuclear envelope. We recently described the discovery that in hippocampal neurons the morphology of the nucleus affects the calcium dynamics within the nucleus. Here we propose that nuclear infoldings determine whether a nucleus functions as an integrator or detector of oscillating calcium signals. We outline possible ties between nuclear mophology and transcriptional activity and discuss the importance of extending the approach to whole cell calcium signal modeling in order to understand synapse-to-nucleus communication in healthy and dysfunctional neurons. PMID:21738832
Dynamic structure factor on liquid Pb
International Nuclear Information System (INIS)
Padureanu, I.; Rapeanu, S.; Rotarascu, G.; Craciun, C.
1979-01-01
Dinamic structure factor S(Q,hω) in liquid Pb has been measured at 350 deg C and 400 deg C using the inelastic scattering of the slow neutrons. The measurements were performed in the momentum transfer range 0.6 A -1 -1 . The intermediate scattering function F(Q,t) is also calculated from S(Q,hω). Multiple scattering calculation shows that it is very large especially at small scattering angles. The comparison of the experimental data with the theory is made in terms of two theoretical models. (author)
Dynamical effects of QCD vacuum structure
International Nuclear Information System (INIS)
Ferreira, Erasmo
1994-01-01
The role of the QCD vacuum structure in the determination of the properties of states and processes occurring in the confinement regime of QCD is reviewed. The finite range of the vacuum correlations is discussed, and an analytical form is suggested for the correlation functions. The role of the vacuum quantum numbers in the phenomenology of high-energy scattering is reviewed. The vacuum correlation model of non-perturbative QCD is mentioned as a bridge between the fundamental theory and the description of the experiments. (author). 13 refs., 1 fig
Dynamical structure of extreme ultraviolet macrospicules
Karovska, Margarita; Habbal, Shadia Rifai
1994-01-01
We describe the substructures forming the macrospicules and their temporal evolution, as revealed by the application of an image enhancement algorithm to extreme ultraviolet (EUV) observations of macrospicules. The enhanced images uncover, for the first time, the substructures forming the column-like structures within the macrospicules and the low-lying arches at their base. The spatial and temporal evolution of macrospicules clearly show continuous interaction between these substructures with occasional ejection of plasma following a ballistic trajectory. We comment on the importance of these results for planning near future space observations of macrospicules with better temporal and spatial resolution.
Effect of support conditions on structural response under dynamic loading
International Nuclear Information System (INIS)
Akram, T.; Memon, S.A.
2008-01-01
In design practice, dynamic structural analysis is carried out with base of structure considered as fixed; this means that foundation is placed on rock like soil material. While conducting this type of analyses the role of foundation and soil behaviour is totally neglected. The actions in members and loads transferred at foundation level obtained in this manner do not depict the true structural behaviour. FEM (Finite Element Methods) analysis where both superstructure and foundation soil are coupled together is quite complicated and expensive for design environments. A simplified model is required to depict dynamic response of structures with foundations based on flexible soils. The primary purpose of this research is to compare the superstructure dynamic responses of structural systems with fixed base to that of simple soil model base. The selected simple soil model is to be suitable for use in a design environment to give more realistic results. For this purpose building models are idealized with various heights and structural systems in both 2D (Two Dimensional) and 3D (Three Dimensional) space. These models are then provided with visco-elastic supports representing three soil bearing capacities and the analysis results are compared to that of fixed supports models. The results indicate that fixed support system underestimates natural time period of the structures. Dynamic behavior and force response of visco-elastic support is different from fixed support model. Fixed support models result in over designed base columns and under designed beams. (author)
PDB2CD visualises dynamics within protein structures.
Janes, Robert W
2017-10-01
Proteins tend to have defined conformations, a key factor in enabling their function. Atomic resolution structures of proteins are predominantly obtained by either solution nuclear magnetic resonance (NMR) or crystal structure methods. However, when considering a protein whose structure has been determined by both these approaches, on many occasions, the resultant conformations are subtly different, as illustrated by the examples in this study. The solution NMR approach invariably results in a cluster of structures whose conformations satisfy the distance boundaries imposed by the data collected; it might be argued that this is evidence of the dynamics of proteins when in solution. In crystal structures, the proteins are often in an energy minimum state which can result in an increase in the extent of regular secondary structure present relative to the solution state depicted by NMR, because the more dynamic ends of alpha helices and beta strands can become ordered at the lower temperatures. This study examines a novel way to display the differences in conformations within an NMR ensemble and between these and a crystal structure of a protein. Circular dichroism (CD) spectroscopy can be used to characterise protein structures in solution. Using the new bioinformatics tool, PDB2CD, which generates CD spectra from atomic resolution protein structures, the differences between, and possible dynamic range of, conformations adopted by a protein can be visualised.
Elements of earthquake engineering and structural dynamics. 2. ed.
International Nuclear Information System (INIS)
Filiatrault, A.
2002-01-01
This book is written for practising engineers, senior undergraduate and junior structural-engineering students, and university educators. Its main goal is to provide basic knowledge to structural engineers who have no previous knowledge about earthquake engineering and structural dynamics. Earthquake engineering is a multidisciplinary science. This book is not limited to structural analysis and design. The basics of other relevant topics (such as geology, seismology, and geotechnical engineering) are also covered to ensure that structural engineers can interact efficiently with other specialists during a construction project in a seismic zone
Plasma turbulence. Structure formation, selection rule, dynamic response and dynamics transport
International Nuclear Information System (INIS)
Ito, Sanae I.
2010-01-01
The five-year project of Grant-in-Aid for Specially Promoted Research entitled general research on the structure formation and selection rule in plasma turbulence had brought many outcomes. Based on these outcomes, the Grant-in-Aid for Scientific Research (S) program entitled general research on dynamic response and dynamic transport in plasma turbulence has started. In the present paper, the state-of-the-art of the research activities on the structure formation, selection rule and dynamics in plasma turbulence are reviewed with reference to outcomes of these projects. (author)
Structure-based control of complex networks with nonlinear dynamics.
Zañudo, Jorge Gomez Tejeda; Yang, Gang; Albert, Réka
2017-07-11
What can we learn about controlling a system solely from its underlying network structure? Here we adapt a recently developed framework for control of networks governed by a broad class of nonlinear dynamics that includes the major dynamic models of biological, technological, and social processes. This feedback-based framework provides realizable node overrides that steer a system toward any of its natural long-term dynamic behaviors, regardless of the specific functional forms and system parameters. We use this framework on several real networks, identify the topological characteristics that underlie the predicted node overrides, and compare its predictions to those of structural controllability in control theory. Finally, we demonstrate this framework's applicability in dynamic models of gene regulatory networks and identify nodes whose override is necessary for control in the general case but not in specific model instances.
DYNAMIC PARTICLE SYSTEMS FOR OBJECT STRUCTURE EXTRACTION
Directory of Open Access Journals (Sweden)
Olivier Lavialle
2011-05-01
Full Text Available A new deformable model based on the use of a particle system is introduced. By defining the local behavior of each particle, the system behaves as an active contour model showing a variable topology and regularization properties. The efficiency of the particle system is illustrated by two applications: the first one concerns the use of the system as a skeleton extractor based on the propagation of particles inside a treeshaped object. Using this method, it is possible to generate a cartography of structures such as veins or channels. In a second illustration, the system avoids the problem of initialization of a piecewise cubic Bspline network used to straighten curved text lines.
International Nuclear Information System (INIS)
Dellerue, Serge
2000-01-01
Understand the structure-dynamics-function relation in the case of proteins is essential. But few experimental techniques allow to have access to knowledge of fast internal movements of biological macromolecules. With the neutron scattering method, it has been possible to study the reorientation dynamics of side chains and of polypeptide skeleton for two proteins in terms of water or detergent and of temperature. With the use of the molecular dynamics method, essential for completing and interpreting the experimental data, it has been possible to assess the different contributions of the whole structure of proteins to the overall dynamics. It has been shown that the polypeptide skeleton presents an energy relaxation comparable to those of the side chains. Moreover, it has been explained that the protein dynamics can only be understood in terms of relaxation time distribution. (author) [fr
Structure and dynamics of weakly bound complexes
International Nuclear Information System (INIS)
Skouteris, D.
1998-01-01
The present thesis deals with the spectroscopic and theoretical investigation of weakly bound complexes involving a methane molecule. Studies of these Van der Waals complexes can give valuable information on the relevant intermolecular dynamics and promote the understanding of the interactions between molecules (which can ultimately lead to chemical reactions). Especially interesting are complexes involving molecules of high symmetry (e.g. tetrahedral, such as methane) because of the unusual effects arising from it (selection rules, nuclear Spin statistical weights etc.). The infrared spectrum of the Van der Waals complex between a CH 4 and a N 2 O molecule has been recorded and most of it has been assigned in the region of the N - O stretch (approximately 2225.0 cm -1 ). Despite the fact that this is really a weakly bound complex, it is nevertheless rigid enough so that the standard model for asymmetric top spectra can be applied to it with the usual quantum numbers. From the value of the inertial defect, it turns out that the methane unit is locked in a rigid configuration within the complex rather than freely rotating. The intermolecular distance as well as the tilting angle of the N 2 O linear unit are determined from the rotational constants. The complex itself turns out to have a T - shaped configuration. The infrared spectrum of the Ar - CH 4 complex at the ν 4 (bending) band of methane is also assigned. This is different from the previous one in that the methane unit rotates almost freely Within the complex. As a result, the quantum numbers used to classify rovibrational energy levels include these of the free unit. The concept of 'overall symmetry' is made use of to rationalise selection rules in various sub-bands of the spectrum. Moreover, new terms in the potential anisotropy Hamiltonian are calculated through the use of the overall symmetry concept. These are termed 'mixed anisotropy' terms since they involve both rotational and vibrational degrees of
PWL approximation of nonlinear dynamical systems, part I: structural stability
International Nuclear Information System (INIS)
Storace, M; De Feo, O
2005-01-01
This paper and its companion address the problem of the approximation/identification of nonlinear dynamical systems depending on parameters, with a view to their circuit implementation. The proposed method is based on a piecewise-linear approximation technique. In particular, this paper describes the approximation method and applies it to some particularly significant dynamical systems (topological normal forms). The structural stability of the PWL approximations of such systems is investigated through a bifurcation analysis (via continuation methods)
The Return to Schooling in Structural Dynamic Models: A Survey
Christian Belzil
2007-01-01
Working paper du GATE 2006-09; This papers contains a survey of the recent literature devoted to the returns to schooling within a dynamic structural framework. I present a historical perspective on the evolution of the literature, from early static models set in a selectivity framework (Willis and Rosen, 1979) to the recent literature, stimulated by Keane and Wolpin (1997), and which uses stochastic dynamic programming techniques. After reviewing the literature thoroughly, I compare the stru...
The assessment of structural dynamics problems in nuclear reactor safety
International Nuclear Information System (INIS)
Liebe, R.
1978-10-01
The paper discusses important physical features of structural dynamics problems in reactor safety. First a general characterization is given of the following problems: Containment deformation due to pool-dynamics during BWR-blowdown; behavior of the core internals due to PWR-blowdown loads; dynamic response of a nuclear power plant during an earthquake; fuel element deformation due to local pressure pulses in an LMFBR core. Several criterias are formulated to classify typical problems so that a better choise can be made both of appropriate mathematical/numerical as well as experimental techniques. The degree of physical coupling between structural dynamics and fluid dynamics is discussed in more detail since it requires particular attention when selecting problem-oriented methods of solution. Some examples are given to illustrate the application and to compare advantages and disadvantages of several numerical methods. Then description is given of experimental techniques in structural dynamics and typical problem areas are identified. Finally some results are presented concerning the fuel element deformation problem in LMFBRs and from the general considerations some important conclusions are summarized. (orig.) 891 RW 892 AP [de
Dynamic characteristics analysis of deployable space structures considering joint clearance
Li, Tuanjie; Guo, Jian; Cao, Yuyan
2011-04-01
The clearance in joints influences the dynamic stability and the performance of deployable space structures (DSS). A virtual experimental modal analysis (VEMA) method is proposed to deal with the effects of joint clearance and link flexibility on the dynamic characteristics of the DSS in this paper. The focus is on the finite element modeling of the clearance joint, VEMA and the modal parameters identification of the DSS. The finite element models (FEM) of the clearance joint and the deployable structure are established in ANSYS. The transient dynamic analysis is conducted to provide the time history data of excitation and response for the VEMA. The fast Fourier transform (FFT) technique is used to transform the data from time domain to frequency domain. The frequency response function is calculated to identify the modal parameters of the deployable structure. Experimental verification is provided to indicate the VEMA method is both a cost and time efficient approach to obtain the dynamic characteristics of the DSS. Finally, we analyze the effects of clearance size and gravity on the dynamic characteristics of the DSS. The analysis results indicate that the joint clearance and gravity strongly influence the dynamic characteristics of the DSS.
Dynamics of a bistable Miura-origami structure
Fang, Hongbin; Li, Suyi; Ji, Huimin; Wang, K. W.
2017-05-01
Origami-inspired structures and materials have shown extraordinary properties and performances originating from the intricate geometries of folding. However, current state of the art studies have mostly focused on static and quasistatic characteristics. This research performs a comprehensive experimental and analytical study on the dynamics of origami folding through investigating a stacked Miura-Ori (SMO) structure with intrinsic bistability. We fabricate and experimentally investigated a bistable SMO prototype with rigid facets and flexible crease lines. Under harmonic base excitation, the SMO exhibits both intrawell and interwell oscillations. Spectrum analyses reveal that the dominant nonlinearities of SMO are quadratic and cubic, which generate rich dynamics including subharmonic and chaotic oscillations. The identified nonlinearities indicate that a third-order polynomial can be employed to approximate the measured force-displacement relationship. Such an approximation is validated via numerical study by qualitatively reproducing the phenomena observed in the experiments. The dynamic characteristics of the bistable SMO resemble those of a Helmholtz-Duffing oscillator (HDO); this suggests the possibility of applying the established tools and insights of HDO to predict origami dynamics. We also show that the bistability of SMO can be programmed within a large design space via tailoring the crease stiffness and initial stress-free configurations. The results of this research offer a wealth of fundamental insights into the dynamics of origami folding, and provide a solid foundation for developing foldable and deployable structures and materials with embedded dynamic functionalities.
Dynamics of a bistable Miura-origami structure.
Fang, Hongbin; Li, Suyi; Ji, Huimin; Wang, K W
2017-05-01
Origami-inspired structures and materials have shown extraordinary properties and performances originating from the intricate geometries of folding. However, current state of the art studies have mostly focused on static and quasistatic characteristics. This research performs a comprehensive experimental and analytical study on the dynamics of origami folding through investigating a stacked Miura-Ori (SMO) structure with intrinsic bistability. We fabricate and experimentally investigated a bistable SMO prototype with rigid facets and flexible crease lines. Under harmonic base excitation, the SMO exhibits both intrawell and interwell oscillations. Spectrum analyses reveal that the dominant nonlinearities of SMO are quadratic and cubic, which generate rich dynamics including subharmonic and chaotic oscillations. The identified nonlinearities indicate that a third-order polynomial can be employed to approximate the measured force-displacement relationship. Such an approximation is validated via numerical study by qualitatively reproducing the phenomena observed in the experiments. The dynamic characteristics of the bistable SMO resemble those of a Helmholtz-Duffing oscillator (HDO); this suggests the possibility of applying the established tools and insights of HDO to predict origami dynamics. We also show that the bistability of SMO can be programmed within a large design space via tailoring the crease stiffness and initial stress-free configurations. The results of this research offer a wealth of fundamental insights into the dynamics of origami folding, and provide a solid foundation for developing foldable and deployable structures and materials with embedded dynamic functionalities.
Algorithm of Dynamic Model Structural Identification of the Multivariable Plant
Directory of Open Access Journals (Sweden)
Л.М. Блохін
2004-02-01
Full Text Available The new algorithm of dynamic model structural identification of the multivariable stabilized plant with observable and unobservable disturbances in the regular operating modes is offered in this paper. With the help of the offered algorithm it is possible to define the “perturbed” models of dynamics not only of the plant, but also the dynamics characteristics of observable and unobservable casual disturbances taking into account the absence of correlation between themselves and control inputs with the unobservable perturbations.
Structure Learning in Stochastic Non-linear Dynamical Systems
Morris, R. D.; Smelyanskiy, V. N.; Luchinsky, D. G.
2005-12-01
A great many systems can be modeled in the non-linear dynamical systems framework, as x˙ = f(x) + ξ(t), where f(x) is the potential function for the system, and ξ(t) is the driving noise. Modeling the potential using a set of basis functions, we derive the posterior for the basis coefficients. A more challenging problem is to determine the set of basis functions that are required to model a particular system. We show that using the Bayesian Information Criteria (BIC) to rank models, and the beam search technique, that we can accurately determine the structure of simple non-linear dynamical system models, and the structure of the coupling between non-linear dynamical systems where the individual systems are known. This last case has important ecological applications, for example in predator-prey systems, where the very structure of the coupling between predator-prey pairs can have great ecological significance.
Matrix of transmission in structural dynamics
International Nuclear Information System (INIS)
Mukherjee, S.
1975-01-01
The problem of close-coupled systems and cantilever type buildings can be treated efficiently by means of the very general and versatile method of transmission matrix. The expression 'matrix of transmission' is used to point out the fact that the method to be described differs fundamentally from another method related to matrix calculus, and also successfully used in vibration problem. In this method, forces and displacements are introduced as the 'unknowns' of the problem. The 'matrix of transmission' relates these quantities at one point of the structure to those at the neighbouring point. The natural frequencies of a freely vibrating elastic system can be found by applying proper end conditions. The end conditions will yield the frequency determinate to zero. By using suitable numerical method, the natural frequencies and mode shapes are determined, by making a frequency sweep within the range of interest. Results of analysis of a typical nuclear building by this method show very close agreement with the results obtained by using ASKA and SAP IV Program
Organoactinide chemistry: synthesis, structure, and solution dynamics
International Nuclear Information System (INIS)
Brennan, J.G.
1985-12-01
This thesis considers three aspects of organoactinide chemistry. In chapter one, a bidentate phosphine ligand was used to kinetically stabilize complexes of the type Cp 2 MX 2 . Ligand redistribution processes are present throughout the synthetic work, as has often been observed in uranium cyclopentadienyl chemistry. The effects of covalent M-L bonding on the solution and solid state properties of U(III) coordination complexes are considered. In particular, the nature of the more subtle interaction between the metal and the neutral ligand are examined. Using relative basicity data obtained in solution, and solid state structural data (and supplemented by gas phase photoelectron measurements), it is demonstrated that the more electron rich U(III) centers engage in significant U → L π-donation. Trivalent uranium is shown to be capable of acting either as a one- or two-electron reducing agent toward a wide variety of unsaturated organic and inorganic molecules, generating molecular classes unobtainable via traditional synthetic approaches, as well as offering an alternative synthetic approach to molecules accessible via metathesis reactions. Ligand redistribution processes are again observed, but given the information concerning ligand lability, this reactivity pattern is applied to the synthesis of pure materials inaccessible from redox chemistry. 214 refs., 33 figs., 10 tabs
In situ structure and dynamics of DNA origami determined through molecular dynamics simulations.
Yoo, Jejoong; Aksimentiev, Aleksei
2013-12-10
The DNA origami method permits folding of long single-stranded DNA into complex 3D structures with subnanometer precision. Transmission electron microscopy, atomic force microscopy, and recently cryo-EM tomography have been used to characterize the properties of such DNA origami objects, however their microscopic structures and dynamics have remained unknown. Here, we report the results of all-atom molecular dynamics simulations that characterized the structural and mechanical properties of DNA origami objects in unprecedented microscopic detail. When simulated in an aqueous environment, the structures of DNA origami objects depart from their idealized targets as a result of steric, electrostatic, and solvent-mediated forces. Whereas the global structural features of such relaxed conformations conform to the target designs, local deformations are abundant and vary in magnitude along the structures. In contrast to their free-solution conformation, the Holliday junctions in the DNA origami structures adopt a left-handed antiparallel conformation. We find the DNA origami structures undergo considerable temporal fluctuations on both local and global scales. Analysis of such structural fluctuations reveals the local mechanical properties of the DNA origami objects. The lattice type of the structures considerably affects global mechanical properties such as bending rigidity. Our study demonstrates the potential of all-atom molecular dynamics simulations to play a considerable role in future development of the DNA origami field by providing accurate, quantitative assessment of local and global structural and mechanical properties of DNA origami objects.
Full scale dynamic testing of Paks nuclear power plant structures
International Nuclear Information System (INIS)
Da Rin, E.M.
1995-01-01
This report refers to the full-scale dynamic structural testing activities that have been performed in December 1994 at the Paks (H) Nuclear Power Plant, within the framework of: the IAEA Coordinated research Programme 'Benchmark Study for the Seismic Analysis and Testing of WWER-type Nuclear Power Plants, and the nuclear research activities of ENEL-WR/YDN, the Italian National Electricity Board in Rome. The specific objective of the conducted investigation was to obtain valid data on the dynamic behaviour of the plant's major constructions, under normal operating conditions, for enabling an assessment of their actual seismic safety to be made. As described in more detail hereafter, the Paks NPP site has been subjected to low level earthquake like ground shaking, through appropriately devised underground explosions, and the dynamic response of the plant's 1 st reactor unit important structures was appropriately measured and digitally recorded. In-situ free field response was measured concurrently and, moreover, site-specific geophysical and seismological data were simultaneously acquired too. The above-said experimental data is to provide basic information on the geophysical and seismological characteristics of the Paks NPP site, together with useful reference information on the true dynamic characteristics of its main structures and give some indications on the actual dynamic soil-structure interaction effects for the case of low level excitation
Two stage approach to dynamic soil structure interaction
International Nuclear Information System (INIS)
Nelson, I.
1981-01-01
A two stage approach is used to reduce the effective size of soil island required to solve dynamic soil structure interaction problems. The ficticious boundaries of the conventional soil island are chosen sufficiently far from the structure so that the presence of the structure causes only a slight perturbation on the soil response near the boundaries. While the resulting finite element model of the soil structure system can be solved, it requires a formidable computational effort. Currently, a two stage approach is used to reduce this effort. The combined soil structure system has many frequencies and wavelengths. For a stiff structure, the lowest frequencies are those associated with the motion of the structure as a rigid body. In the soil, these modes have the longest wavelengths and attenuate most slowly. The higher frequency deformational modes of the structure have shorter wavelengths and their effect attenuates more rapidly with distance from the structure. The difference in soil response between a computation with a refined structural model, and one with a crude model, tends towards zero a very short distance from the structure. In the current work, the 'crude model' is a rigid structure with the same geometry and inertial properties as the refined model. Preliminary calculations indicated that a rigid structure would be a good low frequency approximation to the actual structure, provided the structure was much stiffer than the native soil. (orig./RW)
Pak, Chan-Gi; Truong, Samson S.
2014-01-01
Small modeling errors in the finite element model will eventually induce errors in the structural flexibility and mass, thus propagating into unpredictable errors in the unsteady aerodynamics and the control law design. One of the primary objectives of Multi Utility Technology Test Bed, X-56A, aircraft is the flight demonstration of active flutter suppression, and therefore in this study, the identification of the primary and secondary modes for the structural model tuning based on the flutter analysis of X-56A. The ground vibration test validated structural dynamic finite element model of the X-56A is created in this study. The structural dynamic finite element model of the X-56A is improved using a model tuning tool. In this study, two different weight configurations of the X-56A have been improved in a single optimization run.
Structural dynamics and vibration 1995. PD-Volume 70
International Nuclear Information System (INIS)
Ovunc, B.A.; Esat, I.I.; Sabir, A.B.; Karadag, V.
1995-01-01
The themes of this symposium focused on: dynamic responses to temperature cycles and wind excitation; the influence of the hydraulic feedback on stability; structural reliability; vibratory stress relief; fault detection by signal processing; dynamic contact in mechanisms; vibration of thick flexible mechanisms; higher order mechanisms in flexible mechanisms; natural circular frequencies by finite element method; elastic buckling, stability, and vibration of linear and nonlinear structures; buckling of stiffened plates and rings; mixed variable optimization; vibration optimization; and optimization in a constrained space. Separate abstracts were prepared for 20 papers in this book
Energy Technology Data Exchange (ETDEWEB)
Car, R.; Parrinello, M.
1988-01-18
An amorphous silicon structure is obtained with a computer simulation based on a new molecular-dynamics technique in which the interatomic potential is derived from a parameter-free quantum mechanical method. Our results for the atomic structure, the phonon spectrum, and the electronic properties are in excellent agreement with experiment. In addition we study details of the microscopic dynamics which are not directly accessible to experiment. We find in particular that structural defects are associated with weak bonds. These may give rise to low-frequency vibrational modes.
DEFF Research Database (Denmark)
van der Velden, Tijl A; Schmitz, Alexander M Th; Gilhuijs, Kenneth G A
2016-01-01
contained 3D T1-weighted gradient echo images obtained with both WSE fat suppression, multi echo Dixon fat suppression, and without fat suppression. Images were acquired at a (0.8mm)(3) or (0.7mm)(3) isotropic resolution with equal field of view and optimized such to obtain a maximal SNR. Image quality...... was scored qualitatively on overall image quality, sharpness of anatomical details, presence of artefacts, inhomogeneous fat suppression and the presence of water-fat shift. A quantitative scoring was obtained from the signal to noise ratio and contrast to noise ratio. RESULTS: WSE scored significantly...... better in terms of overall image quality and the absence of artefacts. No significant difference in contrast to noise ratio was found between the two fat suppression methods. CONCLUSION: When maximizing temporal and spatial resolution of high resolution DCE MRI of the breast, water selective excitation...
Chimaerin suppresses Rac1 activation at the apical membrane to maintain the cyst structure.
Directory of Open Access Journals (Sweden)
Shunsuke Yagi
Full Text Available Epithelial organs are made of a well-polarized monolayer of epithelial cells, and their morphology is maintained strictly for their proper functions. Previously, we showed that Rac1 activation is suppressed at the apical membrane in the mature organoid, and that such spatially biased Rac1 activity is required for the polarity maintenance. Here we identify Chimaerin, a GTPase activating protein for Rac1, as a suppressor of Rac1 activity at the apical membrane. Depletion of Chimaerin causes over-activation of Rac1 at the apical membrane in the presence of hepatocyte growth factor (HGF, followed by luminal cell accumulation. Importantly, Chimaerin depletion did not inhibit extension formation at the basal membrane. These observations suggest that Chimaerin functions as the apical-specific Rac1 GAP to maintain epithelial morphology.
International Nuclear Information System (INIS)
Davis, E.C.; Stansfield, R.G.; Melroy, L.A.; Huff, D.D.
1984-01-01
Shallow depth to groundwater, surface drainage, and subsurface flow during storm events are major environmental concerns of low-level radioactive waste management operations in humid regions. At two waste disposal sites within the Oak Ridge National Laboratory (ORNL), groups of closed trenches have experienced these problems and have been shown to collect and hold water with seasonal fluctuations ranging from 1 to 2 m. In an attempt to correct these water-related problems, the older of the two sites [Solid Waste Storage Area Four (SWSA 4)] was equipped in September 1975 with asphalt lined drainage-ways designed to prevent infiltration of storm drainage from a 13.8-ha upslope catchment. At the second site (49-Trench area of SWSA 6), the entire 0.44-ha trench area was capped with a bentonite clay cover in 1976. These attempts have not corrected the water problems. In September 1983, engineered drainage projects were initiated at both the disposal sites. The SWSA 4 project was designed to divert surface runoff and shallow subsurface flow which originates upslope of the site away from the disposal area. The second project, a passive French drain constructed in SWSA 6, was aimed strictly at suppressing the site water table, thus preventing its intersection with the bottoms of disposal trenches. Postconstruction monitoring for performance evaluation has shown that the water table in the 49-Trench area has been suppressed to a depth > 4.9 m below the ground surface over 50% of the site as compared to a depth of only 2.1 m for certain parts of the same area observed during seasonally wet months prior to drain construction. The SWSA 4 project evaluation indicates that 56% of the Winter-Spring 1984 runoff was diverted around SWSA 4 via the drainage system
Groundwater suppression and diversion structures applied to closed shallow land burial trenches
International Nuclear Information System (INIS)
Davis, E.C.; Melroy, L.A.; Huff, D.D.
1984-01-01
Shallow depth to groundwater, surface drainage, and subsurface flow during storm events are major environmental concerns of low-level radioactive waste management operations in humid regions. At two waste disposal sites within the Oak Ridge National Laboratory (ORNL), groups of closed trenches have experienced these problems and have been shown to collect and hold intratrench water with seasonal fluctuations ranging from 1 to 2 m. In an attempt to correct these water-related problems, Solid Waste Storage Area Four (SWSA-4) was equipped in September 1975 with asphalt-lined drainage ways designed to prevent reinfiltration of storm drainage from the 13.8 ha upslope catchment. At 49-Trench Area of SWSA-6 the entire 0.44 ha trench area was capped with a bentonite clay cover in 1976. These early attempts at hydrologic isolation have not corrected the water problems. In September 1983, two similarly designed engineered drainage projects were initiated at the disposal sites. The SWSA-4 project was designed to divert surface runoff around the trench area and drain a portion of the shallow subsurface flow which originates upslope of the site. The second project, a passive French drain constructed in SWSA-6, was aimed strictly at suppressing the site water table thus preventing its intersection with the bottoms of disposal trenches. Post-construction monitoring for performance evaluation has shown that the water table in the 49-trench area has been suppressed to a depth >4.9 m below the ground surface over 50% of the site with a maximum drawdown of 4 m at the drains deepest point. The SWSA-4 project evaluation is just being completed and data show that 56 +/- 15% of the Winter-Spring 1984 runoff was diverted around SWSA 4. As a result, a 44% reduction in 90 Sr flux was calculated from observed discharges and a previously established relation between flow rate and 90 Sr concentration
Dynamic soil-structure interactions on embedded buildings
International Nuclear Information System (INIS)
Kobarg, J.; Werkle, H.; Henseleit, O.
1983-01-01
The dynamic soil-structure interaction on the horizontal seismic excitation is investigated on two typical embedded auxiliary buildings of a nuclear power plant. The structure and the soil are modelled by various analytical and numerical methods. Under the condition of the linear viscoelastic theory, i.e. soil characteristic constant in time and independent of strain, the interaction influences between a homogenous soil layer and a structure are analysied for the following parameters: 4) mathematical soil modells; 4) mathematical structure modells; 4) shear wave velocities; 3) embedment conditions; 4) earthquake time histories. (orig.) [de
Gas Price Formation, Structure and Dynamics
Energy Technology Data Exchange (ETDEWEB)
Davoust, R.
2008-07-01
Our study, focused on gas prices in importing economies, describes wholesale prices and retail prices, their evolution for the last one or two decades, the economic mechanisms of price formation. While an international market for oil has developed thanks to moderate storage and transportation charges, these costs are much higher in the case of natural gas, which involves that this energy is still traded inside continental markets. There are three regional gas markets around the world: North America (the United States, importing mainly from Canada and Mexico), Europe (importing mainly from Russia, Algeria and Norway) and Asia (Japan, Korea, Taiwan, China and India, importing mainly from Indonesia, Malaysia and Australia). A market for gas has also developed in South America, but it will not be covered by our paper. In Europe and the US, due to large domestic resources and strong grids, natural gas is purchased mostly through pipelines. In Northeast Asia, there is a lack of such infrastructures, so imported gas takes mainly the form of Liquefied Natural Gas (LNG), shipped on maritime tankers. Currently, the LNG market is divided into two zones: the Atlantic Basin (Europe and US) and the Pacific Basin (Asia and the Western Coast of America). For the past few years, the Middle East and Africa have tended to be crucial suppliers for both LNG zones. Gas price formation varies deeply between regional markets, depending on several structural factors (regulation, contracting practises, existence of a spot market, liquidity, share of imports). Empirically, the degree of market opening (which corresponds to the seniority in the liberalization process) seems to be the primary determinant of pricing patterns. North America has the most liberalized and well-performing natural gas industry in the world. Gas pricing is highly competitive and is based on supply/demand balances. Spot and futures markets are developed. The British gas sector is also deregulated and thus follows a
Gas Price Formation, Structure and Dynamics
International Nuclear Information System (INIS)
Davoust, R.
2008-01-01
Our study, focused on gas prices in importing economies, describes wholesale prices and retail prices, their evolution for the last one or two decades, the economic mechanisms of price formation. While an international market for oil has developed thanks to moderate storage and transportation charges, these costs are much higher in the case of natural gas, which involves that this energy is still traded inside continental markets. There are three regional gas markets around the world: North America (the United States, importing mainly from Canada and Mexico), Europe (importing mainly from Russia, Algeria and Norway) and Asia (Japan, Korea, Taiwan, China and India, importing mainly from Indonesia, Malaysia and Australia). A market for gas has also developed in South America, but it will not be covered by our paper. In Europe and the US, due to large domestic resources and strong grids, natural gas is purchased mostly through pipelines. In Northeast Asia, there is a lack of such infrastructures, so imported gas takes mainly the form of Liquefied Natural Gas (LNG), shipped on maritime tankers. Currently, the LNG market is divided into two zones: the Atlantic Basin (Europe and US) and the Pacific Basin (Asia and the Western Coast of America). For the past few years, the Middle East and Africa have tended to be crucial suppliers for both LNG zones. Gas price formation varies deeply between regional markets, depending on several structural factors (regulation, contracting practises, existence of a spot market, liquidity, share of imports). Empirically, the degree of market opening (which corresponds to the seniority in the liberalization process) seems to be the primary determinant of pricing patterns. North America has the most liberalized and well-performing natural gas industry in the world. Gas pricing is highly competitive and is based on supply/demand balances. Spot and futures markets are developed. The British gas sector is also deregulated and thus follows a
The structure and dynamics of boron nitride nanoscrolls
International Nuclear Information System (INIS)
Perim, Eric; Galvao, Douglas S
2009-01-01
Carbon nanoscrolls (CNSs) are structures formed by rolling up graphene layers into a scroll-like shape. CNNs have been experimentally produced by different groups. Boron nitride nanoscrolls (BNNSs) are similar structures using boron nitride instead of graphene layers. In this paper we report molecular mechanics and molecular dynamics results for the structural and dynamical aspects of BNNS formation. Similarly to CNS, BNNS formation is dominated by two major energy contributions, the increase in the elastic energy and the energetic gain due to van der Waals interactions of the overlapping surface of the rolled layers. The armchair scrolls are the most stable configuration while zigzag scrolls are metastable structures which can be thermally converted to armchairs. Chiral scrolls are unstable and tend to evolve into zigzag or armchair configurations depending on their initial geometries. The possible experimental routes to produce BNNSs are also addressed.
Stochastic Erosion of Fractal Structure in Nonlinear Dynamical Systems
Agarwal, S.; Wettlaufer, J. S.
2014-12-01
We analyze the effects of stochastic noise on the Lorenz-63 model in the chaotic regime to demonstrate a set of general issues arising in the interpretation of data from nonlinear dynamical systems typical in geophysics. The model is forced using both additive and multiplicative, white and colored noise and it is shown that, through a suitable choice of the noise intensity, both additive and multiplicative noise can produce similar dynamics. We use a recently developed measure, histogram distance, to show the similarity between the dynamics produced by additive and multiplicative forcing. This phenomenon, in a nonlinear fractal structure with chaotic dynamics can be explained by understanding how noise affects the Unstable Periodic Orbits (UPOs) of the system. For delta-correlated noise, the UPOs erode the fractal structure. In the presence of memory in the noise forcing, the time scale of the noise starts to interact with the period of some UPO and, depending on the noise intensity, stochastic resonance may be observed. This also explains the mixing in dissipative dynamical systems in presence of white noise; as the fractal structure is smoothed, the decay of correlations is enhanced, and hence the rate of mixing increases with noise intensity.
Structure and dynamics of aqueous solution of uranyl ions
International Nuclear Information System (INIS)
Chopra, Manish; Choudhury, Niharendu
2014-01-01
The present work describes a molecular dynamics simulation study of structure and dynamics of aqueous solution of uranyl ions in water. Structural properties of the system in terms of radial distribution functions and dynamical characteristics as obtained through velocity autocorrelation function and mean square displacements have been analyzed. The results for radial distribution functions show the oxygen of water to form the first solvation shell at 2.4 Å around the uranium atom, whereas the hydrogen atoms of water are distributed around the uranium atom with the major peak at around 3.0 Å. Analyses of transport behaviors of ions and water through MSD indicates that the diffusion of the uranyl ion is much less as compared to that of the water molecules. It is also observed that the dynamical behavior of water molecules gets modified due to the presence of uranyl ion. The effect of increase in concentration of uranyl ions on the structure and dynamics of water molecules is also studied
International Nuclear Information System (INIS)
Carrillo, Jan-Michael Y.; Sumpter, Bobby G.
2014-01-01
Coarse-grained molecular dynamics simulations are used to probe the dynamic phenomena of polymer melts confined in nanopores. The simulation results show excellent agreement in the values obtained for the normalized coherent single chain dynamic structure factor, (S(Q,Δt))/(S(Q,0)) . In the bulk configuration, both simulations and experiments confirm that the polymer chains follow Rouse dynamics. However, under confinement, the Rouse modes are suppressed. The mean-square radius of gyration 〈R g 2 〉 and the average relative shape anisotropy 〈κ 2 〉 of the conformation of the polymer chains indicate a pancake-like conformation near the surface and a bulk-like conformation near the center of the confining cylinder. This was confirmed by direct visualization of the polymer chains. Despite the presence of these different conformations, the average form factor of the confined chains still follows the Debye function which describes linear ideal chains, which is in agreement with small angle neutron scattering experiments (SANS). The experimentally inaccessible mean-square displacement (MSD) of the confined monomers, calculated as a function of radial distance from the pore surface, was obtained in the simulations. The simulations show a gradual increase of the MSD from the adsorbed, but mobile layer, to that similar to the bulk far away from the surface
Interfacial ionic 'liquids': connecting static and dynamic structures.
Uysal, Ahmet; Zhou, Hua; Feng, Guang; Lee, Sang Soo; Li, Song; Cummings, Peter T; Fulvio, Pasquale F; Dai, Sheng; McDonough, John K; Gogotsi, Yury; Fenter, Paul
2015-01-28
It is well known that room temperature ionic liquids (RTILs) often adopt a charge-separated layered structure, i.e. with alternating cation- and anion-rich layers, at electrified interfaces. However, the dynamic response of the layered structure to temporal variations in applied potential is not well understood. We used in situ, real-time x-ray reflectivity to study the potential-dependent electric double layer (EDL) structure of an imidazolium-based RTIL on charged epitaxial graphene during potential cycling as a function of temperature. The results suggest that the graphene-RTIL interfacial structure is bistable in which the EDL structure at any intermediate potential can be described by the combination of two extreme-potential structures whose proportions vary depending on the polarity and magnitude of the applied potential. This picture is supported by the EDL structures obtained by fully atomistic molecular dynamics simulations at various static potentials. The potential-driven transition between the two structures is characterized by an increasing width but with an approximately fixed hysteresis magnitude as a function of temperature. The results are consistent with the coexistence of distinct anion- and cation-adsorbed structures separated by an energy barrier (∼0.15 eV).
32nd IMAC Conference and Exposition on Structural Dynamics
Mayes, Randy; Rixen, Daniel; Catbas, Fikret; Atamturktur, H; Moaveni, Babak; Papadimitriou, Costas; Schoenherr, Tyler; Foss, Gary; Niezrecki, Christopher; Allemang, Randall; Kerschen, Gaetan
2014-01-01
This critical collection examines a range of topics in modal analysis, from experimental techniques to acoustics to biodynamics, as presented in early findings and case studies from the Proceedings of the 32nd IMAC, A Conference and Exposition on Structural Dynamics, 2014. The collection includes papers in the following general technical research areas: Experimental Techniques, Processing Modal Data, Rotating Machinery, Acoustics, Adaptive Structures, Biodynamics, Damping
Proton structure functions in the dipole picture of BFKL dynamics
International Nuclear Information System (INIS)
Navelet, H.; Peschanski, R.; Wallon, S.; Royon, Ch.
1996-06-01
The proton structure functions are derived in the QCD dipole picture. Assuming k T and renormalization-group factorization, deep-inelastic proton scattering is related to deep-inelastic onium scattering. A three parameter fit of the 1994 H1 data in the low-x, moderate Q 2 range has been obtained. The dipole picture of BFKL dynamics is shown to provide a relevant model for quantitatively describing the proton structure functions at HERA. (author)
Capital Structure, Environmental Dynamism, Innovation Strategy, and Strategic Risk Management
DEFF Research Database (Denmark)
Juul Andersen, Torben
2005-01-01
Previous research found that capital structure affects performance when it is adapted to the level of environmental dynamism and pursuit of an innovation strategy. The current study reproduces some of these relationships in a more recent dataset but also identifies significant nuances across...... industrial environments. Analyses of a large cross sectional sample and various industry sub-samples suggest that other factors have influenced capital structure effects in recent years including flexibilities in multinational organization and effective strategic risk management capabilities....
Zhu, Lu; Xi, Li
2018-04-01
Drag reduction induced by polymer additives in wall-bounded turbulence has been studied for decades. A small dosage of polymer additives can drastically reduce the energy dissipation in turbulent flows and alter the flow structures at the same time. As the polymer-induced fluid elasticity increases, drag reduction goes through several stages of transition with drastically different flow statistics. While much attention in the area of polymer-turbulence interactions has been focused on the onset and the asymptotic stage of maximum drag reduction, the transition between the two intermediate stages – low-extent drag reduction (LDR) and high-extent drag reduction (HDR) – likely reflects a qualitative change in the underlying vortex dynamics according to our recent study [1]. In particular, we proposed that polymers start to suppress the lift-up and bursting of vortices at HDR, leading to the localization of turbulent structures. To test our hypothesis, a statistically robust conditional sampling algorithm, based on Jenong and Hussain [2]’s work, was adopted in this study. The comparison of conditional eddies between the Newtonian and the highly elastic turbulence shows that (i) the lifting “strength” of vortices is suppressed by polymers as reflected by the decreasing lifting angle of the conditional eddy and (ii) the curvature of vortices is also eliminated as the orientation of the head of the conditional eddy changes. In summary, the results of conditional sampling support our hypothesis of polymer-turbulence interactions during the LDR-HDR transition.
Development of structural health monitoring techniques using dynamics testing
Energy Technology Data Exchange (ETDEWEB)
James, G.H. III [Sandia National Labs., Albuquerque, NM (United States). Experimental Structural Dynamics Dept.
1996-03-01
Today`s society depends upon many structures (such as aircraft, bridges, wind turbines, offshore platforms, buildings, and nuclear weapons) which are nearing the end of their design lifetime. Since these structures cannot be economically replaced, techniques for structural health monitoring must be developed and implemented. Modal and structural dynamics measurements hold promise for the global non-destructive inspection of a variety of structures since surface measurements of a vibrating structure can provide information about the health of the internal members without costly (or impossible) dismantling of the structure. In order to develop structural health monitoring for application to operational structures, developments in four areas have been undertaken within this project: operational evaluation, diagnostic measurements, information condensation, and damage identification. The developments in each of these four aspects of structural health monitoring have been exercised on a broad range of experimental data. This experimental data has been extracted from structures from several application areas which include aging aircraft, wind energy, aging bridges, offshore structures, structural supports, and mechanical parts. As a result of these advances, Sandia National Laboratories is in a position to perform further advanced development, operational implementation, and technical consulting for a broad class of the nation`s aging infrastructure problems.
Dignam, Bryony E A; O'Callaghan, Maureen; Condron, Leo M; Kowalchuk, George A; Van Nostrand, Joy D; Zhou, Jizhong; Wakelin, Steven A
2018-01-01
Cropping soils vary in extent of natural suppression of soil-borne plant diseases. However, it is unknown whether similar variation occurs across pastoral agricultural systems. We examined soil microbial community properties known to be associated with disease suppression across 50 pastoral fields varying in management intensity. The composition and abundance of the disease-suppressive community were assessed from both taxonomic and functional perspectives. Pseudomonas bacteria were selected as a general taxonomic indicator of disease suppressive potential, while genes associated with the biosynthesis of a suite of secondary metabolites provided functional markers (GeoChip 5.0 microarray analysis). The composition of both the Pseudomonas communities and disease suppressive functional genes were responsive to land use. Underlying soil properties explained 37% of the variation in Pseudomonas community structure and up to 61% of the variation in the abundance of disease suppressive functional genes. Notably, measures of soil organic matter quality, C:P ratio, and aromaticity of the dissolved organic matter content (carbon recalcitrance), influenced both the taxonomic and functional disease suppressive potential of the pasture soils. Our results suggest that key components of the soil microbial community may be managed on-farm to enhance disease suppression and plant productivity.
Functional clustering in hippocampal cultures: relating network structure and dynamics
International Nuclear Information System (INIS)
Feldt, S; Dzakpasu, R; Olariu, E; Żochowski, M; Wang, J X; Shtrahman, E
2010-01-01
In this work we investigate the relationship between gross anatomic structural network properties, neuronal dynamics and the resultant functional structure in dissociated rat hippocampal cultures. Specifically, we studied cultures as they developed under two conditions: the first supporting glial cell growth (high glial group), and the second one inhibiting it (low glial group). We then compared structural network properties and the spatio-temporal activity patterns of the neurons. Differences in dynamics between the two groups could be linked to the impact of the glial network on the neuronal network as the cultures developed. We also implemented a recently developed algorithm called the functional clustering algorithm (FCA) to obtain the resulting functional network structure. We show that this new algorithm is useful for capturing changes in functional network structure as the networks evolve over time. The FCA detects changes in functional structure that are consistent with expected dynamical differences due to the impact of the glial network. Cultures in the high glial group show an increase in global synchronization as the cultures age, while those in the low glial group remain locally synchronized. We additionally use the FCA to quantify the amount of synchronization present in the cultures and show that the total level of synchronization in the high glial group is stronger than in the low glial group. These results indicate an interdependence between the glial and neuronal networks present in dissociated cultures
Dynamic analysis on market structure of China's coal industry
International Nuclear Information System (INIS)
Yang, Qing; Zhang, Lei; Wang, Xin
2017-01-01
According to industrial organization theory, market structure is a crucial factor to market performance. Based on the VAR model and the data from 1994 to 2014, we revealed the dynamic response route of the market structure to these factors and the change process of contribution rate of these factors to the market structure. It shows that market structure is inertial adjustment; technology advance and industry policy have continuous effects on improvement of market concentration ratio; market size and production scale have sustained negative effects on market concentration ratio; fixed capital has barrier effect, which is mainly the entry barrier effect at the beginning, and then the exit barrier effect continues to play a leading role. Therefore, the government has no need to introduce special policies to encourage merger or expansion on the capacity as enterprises would do it spontaneously; it is necessary to make market access system stricter, to improve exit compensation mechanism and to promote technological innovation; all these policies need dynamic adjustment based on the stages of economic cycle. - Highlights: • The adjustment mechanism of China's coal market structure is revealed. • Technology and industry policy are significant factors to optimize the market structure. • The government need not introduce special policy to encourage merger. • The market access system should be stricter. • Policies strength should be dynamically adjusted based on the economic cycle.
Structural relaxation dynamics and annealing effects of sodium silicate glass.
Naji, Mohamed; Piazza, Francesco; Guimbretière, Guillaume; Canizarès, Aurélien; Vaills, Yann
2013-05-09
Here we report high-precision measurements of structural relaxation dynamics in the glass transition range at the intermediate and short length scale for a strong sodium silicate glass during long annealing times. We evidence for the first time the heterogeneous dynamics at the intermediate range order by probing the acoustic longitudinal frequency in the GHz region by Brillouin light scattering spectroscopy. Or, from in-situ Raman measurements, we show that relaxation is indeed homogeneous at the interatomic length scale. Our results show that the dynamics at the intermediate range order contains two distinct relaxation time scales, a fast and a slow component, differing by about a 10-fold factor below Tg and approaching to one another past the glass transition. The slow relaxation time agrees with the shear relaxation time, proving that Si-O bond breaking constitutes the primary control of structural relaxation at the intermediate range order.
Parameter and Structure Inference for Nonlinear Dynamical Systems
Morris, Robin D.; Smelyanskiy, Vadim N.; Millonas, Mark
2006-01-01
A great many systems can be modeled in the non-linear dynamical systems framework, as x = f(x) + xi(t), where f() is the potential function for the system, and xi is the excitation noise. Modeling the potential using a set of basis functions, we derive the posterior for the basis coefficients. A more challenging problem is to determine the set of basis functions that are required to model a particular system. We show that using the Bayesian Information Criteria (BIC) to rank models, and the beam search technique, that we can accurately determine the structure of simple non-linear dynamical system models, and the structure of the coupling between non-linear dynamical systems where the individual systems are known. This last case has important ecological applications.
Shafer, M. W.; McKee, G. R.; Schlossberg, D. J.; Austin, M. E.; Burrell, K. H.
2008-11-01
Long-wavelength turbulence (kρiITBs) may form. Application of off-axis ECH slows the q-profile evolution and increases ρqmin, both of which enhance turbulence measurements using a new high-sensitivity large-area (8x,8) 2D BES array. The measured transient turbulence suppression is localized to the low-order rational surface (qmin= 2, 5/2, 3, etc.). Measured poloidal flow shear transiently exceeds the turbulence decorrelation rate, which is consistent with shear suppression. The localized suppression zone propagates radially outward, nearly coincident with the low-order surface.
The Fine Structure of Equity-Index Option Dynamics
DEFF Research Database (Denmark)
Andersen, Torben G.; Bondarenko, Oleg; Todorov, Viktor
We analyze the high-frequency dynamics of S&P 500 equity-index option prices by constructing an assortment of implied volatility measures. This allows us to infer the underlying fine structure behind the innovations in the latent state variables driving the movements of the volatility surface...
Zooplankton community structure and dynamics during the transition ...
African Journals Online (AJOL)
This study investigates the zooplankton community structure and dynamics of Kufena Rock Pool during the transition from dry season (March to April) to rainy season (May to June) in Zaria, Nigeria. Physicochemical parameters such as temperature, hydrogen ion concentration, electrical conductivity and total dissolved ...
Progression of 3D Protein Structure and Dynamics Measurements
Sato-Tomita, Ayana; Sekiguchi, Hiroshi; Sasaki, Yuji C.
2018-06-01
New measurement methodologies have begun to be proposed with the recent progress in the life sciences. Here, we introduce two new methodologies, X-ray fluorescence holography for protein structural analysis and diffracted X-ray tracking (DXT), to observe the dynamic behaviors of individual single molecules.
Structure of hydrogenated amorphous silicon from ab initio molecular dynamics
Energy Technology Data Exchange (ETDEWEB)
Buda, F. (Department of Physics, The Ohio State University, 174 West 18th Avenue, Columbus, Ohio (USA)); Chiarotti, G.L. (International School for Advanced Studies, Strada Costiera 11, I-34014 Trieste (Italy) Laboratorio Tecnologie Avanzate Superfici e Catalisi del Consorzio Interuniversitario Nazionale di Fisica della Materia, Padriciano 99, I-34012 Trieste (Italy)); Car, R. (International School for Advanced Studies, Strada Costiera 11, I-34014 Trieste (Italy) Institut Romard de Recherche Numerique en Physique des Materiaux, CH-1015 Lausanne, Switzerland Department of Condensed Matter Physics, University of Geneva, CH-1211 Geneva (Switzerland)); Parrinello, M. (IBM Research Division, Zurich Research Laboratory, CH-8803 Rueschlikon (Switzerland))
1991-09-15
We have generated a model of hydrogenated amorphous silicon by first-principles molecular dynamics. Our results are in good agreement with the available experimental data and provide new insight into the microscopic structure of this material. The calculation lends support to models in which monohydride complexes are prevalent, and indicates a strong tendency of hydrogen to form small clusters.
Gauge-invariant cosmic structures---A dynamic systems approach
International Nuclear Information System (INIS)
Woszczyna, A.
1992-01-01
Gravitational instability is expressed in terms of the dynamic systems theory. The gauge-invariant Ellis-Bruni equation and Bardeen's equation are discussed in detail. It is shown that in an open universe filled with matter of constant sound velocity the Jeans criterion does not adequately define the length scale of the gravitational structure
A new dynamic null model for phylogenetic community structure
Pigot, Alex L; Etienne, Rampal S
Phylogenies are increasingly applied to identify the mechanisms structuring ecological communities but progress has been hindered by a reliance on statistical null models that ignore the historical process of community assembly. Here, we address this, and develop a dynamic null model of assembly by
Isomorph invariance of the structure and dynamics of classical crystals
DEFF Research Database (Denmark)
Albrechtsen, Dan; Olsen, Andreas Elmerdahl; Pedersen, Ulf Rørbæk
2014-01-01
This paper shows by computer simulations that some crystalline systems have curves in their thermodynamic phase diagrams, so-called isomorphs, along which structure and dynamics in reduced units are invariant to a good approximation. The crystals are studied in a classical-mechanical framework...
Nuclear visions enhanced: chromatin structure, organization and dynamics
Meshorer, Eran; Herrmann, Harald; Raška, Ivan
2011-01-01
The EMBO Workshop on ‘Chromatin Structure, Organization and Dynamics' took place in April 2011 in Prague, Czech Republic. Participants presented data on the generation of models of the genome, working to correlate changes in the organization of chromatin with the functional state of the genome.
From dynamics to structure and function of model biomolecular systems
Fontaine-Vive-Curtaz, F.
2007-01-01
The purpose of this thesis was to extend recent works on structure and dynamics of hydrogen bonded crystals to model biomolecular systems and biological processes. The tools that we have used are neutron scattering (NS) and density functional theory (DFT) and force field (FF) based simulation
Fluorescence relaxation spectroscopy : light on dynamical structures of flavoproteins
Burten - Bastiaens, P.I.H.
1992-01-01
Refinements in technique and data analysis have opened new avenues for a detailed interpretation of protein fluorescence. What is more, by combining new insights in protein structure and dynamics with improved knowledge of photophysics of biological chromophores, the coupling between
Dynamics and control of twisting bi-stable structures
Arrieta, Andres F.; van Gemmeren, Valentin; Anderson, Aaron J.; Weaver, Paul M.
2018-02-01
Compliance-based morphing structures have the potential to offer large shape adaptation, high stiffness and low weight, while reducing complexity, friction, and scalability problems of mechanism based systems. A promising class of structure that enables these characteristics are multi-stable structures given their ability to exhibit large deflections and rotations without the expensive need for continuous actuation, with the latter only required intermittently. Furthermore, multi-stable structures exhibit inherently fast response due to the snap-through instability governing changes between stable states, enabling rapid configuration switching between the discrete number of programmed shapes of the structure. In this paper, the design and utilisation of the inherent nonlinear dynamics of bi-stable twisting I-beam structures for actuation with low strain piezoelectric materials is presented. The I-beam structure consists of three compliant components assembled into a monolithic single element, free of moving parts, and showing large deflections between two stable states. Finite element analysis is utilised to uncover the distribution of strain across the width of the flange, guiding the choice of positioning for piezoelectric actuators. In addition, the actuation authority is maximised by calculating the generalised coupling coefficient for different positions of the piezoelectric actuators. The results obtained are employed to tailor and test I-beam designs exhibiting desired large deflection between stable states, while still enabling the activation of snap-through with the low strain piezoelectric actuators. To this end, the dynamic response of the I-beams to piezoelectric excitation is investigated, revealing that resonant excitations are insufficient to dynamically trigger snap-through. A novel bang-bang control strategy, which exploits the nonlinear dynamics of the structure successfully triggers both single and constant snap-through between the stable states
Dynamical Heterogeneity in Granular Fluids and Structural Glasses
Avila, Karina E.
Our current understanding of the dynamics of supercooled liquids and other similar slowly evolving (glassy) systems is rather limited. One aspect that is particularly poorly understood is the origin and behavior of the strong non trivial fluctuations that appear in the relaxation process toward equilibrium. Glassy systems and granular systems both present regions of particles moving cooperatively and at different rates from other regions. This phenomenon is known as spatially heterogeneous dynamics. A detailed explanation of this phenomenon may lead to a better understanding of the slow relaxation process, and perhaps it could even help to explain the presence of the glass transition. This dissertation concentrates on studying dynamical heterogeneity by analyzing simulation data for models of granular materials and structural glasses. For dissipative granular fluids, the growing behavior of dynamical heterogeneities is studied for different densities and different degrees of inelasticity in the particle collisions. The correlated regions are found to grow rapidly as the system approaches dynamical arrest. Their geometry is conserved even when probing at different cutoff length in the correlation function or when the energy dissipation in the system is increased. For structural glasses, I test a theoretical framework that models dynamical heterogeneity as originated in the presence of Goldstone modes, which emerge from a broken continuous time reparametrization symmetry. This analysis is based on quantifying the size and the spatial correlations of fluctuations in the time variable and of other kinds of fluctuations. The results obtained here agree with the predictions of the hypothesis. In particular, the fluctuations associated to the time reparametrization invariance become stronger for low temperatures, long timescales, and large coarse graining lengths. Overall, this research points to dynamical heterogeneity to be described for granular systems similarly than
DEFF Research Database (Denmark)
Luczak, Marcin; Peeters, Bart; Kahsin, Maciej
2014-01-01
for uncertainty evaluation in experimentally estimated models. Investigated structures are plates, fuselage panels and helicopter main rotor blades as they represent different complexity levels ranging from coupon, through sub-component up to fully assembled structures made of composite materials. To evaluate......Aerospace and wind energy structures are extensively using components made of composite materials. Since these structures are subjected to dynamic environments with time-varying loading conditions, it is important to model their dynamic behavior and validate these models by means of vibration...
Directory of Open Access Journals (Sweden)
Pan Dan-guang
2015-01-01
Full Text Available For realizing the variation of structural dynamic characteristics due to neighbor structure in buildings group, the surface structure is idealized as an equivalent single degree of freedom system with rigid base whose site consists of a single homogeneous layer. Based on the model, a equivalent method on the equivalent seismic excitation is proposed. Then, the differences of seismic response and equivalent seismic input between soil - structure interaction (SSI system and structure -soil-structure interaction (SSSI system are investigated by harmonic analysis. The numerical results show that dynamic responses would be underestimated in SSSI system when the forcing frequencies are close to the Natural frequency if the effects of neighborhood structure were ignored. Neighborhood structure would make the translational displacement increase and rocking vibration decrease. When establishing an effective seismic input, it is necessary to consider the impact of inertia interaction.
Metastable structures and size effects in small group dynamics.
Lauro Grotto, Rosapia; Guazzini, Andrea; Bagnoli, Franco
2014-01-01
In his seminal works on group dynamics Bion defined a specific therapeutic setting allowing psychoanalytic observations on group phenomena. In describing the setting he proposed that the group was where his voice arrived. This physical limit was later made operative by assuming that the natural dimension of a therapeutic group is around 12 people. Bion introduced a theory of the group aspects of the mind in which proto-mental individual states spontaneously evolve into shared psychological states that are characterized by a series of features: (1) they emerge as a consequence of the natural tendency of (both conscious and unconscious) emotions to combine into structured group patterns; (2) they have a certain degree of stability in time; (3) they tend to alternate so that the dissolution of one is rapidly followed by the emergence of another; (4) they can be described in qualitative terms according to the nature of the emotional mix that dominates the state, in structural terms by a kind of typical "leadership" pattern, and in "cognitive" terms by a set of implicit expectations that are helpful in explaining the group behavior (i.e., the group behaves "as if" it was assuming that). Here we adopt a formal approach derived from Socio-physics in order to explore some of the structural and dynamic properties of this small group dynamics. We will described data from an analytic DS model simulating small group interactions of agents endowed with a very simplified emotional and cognitive dynamic in order to assess the following main points: (1) are metastable collective states allowed to emerge in the model and if so, under which conditions in the parameter space? (2) can these states be differentiated in structural terms? (3) to what extent are the emergent dynamic features of the systems dependent of the system size? We will finally discuss possible future applications of the quantitative descriptions of the interaction structure in the small group clinical setting.
Metastable structures and size effects in small group dynamics
Directory of Open Access Journals (Sweden)
Rosapia eLauro Grotto
2014-07-01
Full Text Available In his seminal works on group dynamics Bion defined a specific therapeutic setting allowing psychoanalytic observations on group phenomena. In describing the setting he proposed that the group was where his voice arrived. This physical limit was later made operative by assuming that the natural dimension of a therapeutic group is around 12 people. Bion introduced a theory of the group aspects of the mind in which proto-mental individual states spontaneously evolve into shared psychological states that are characterized by a series of features: 1 they emerge as a consequence of the natural tendency of (both conscious and unconscious emotions to combine into structured group patterns; 2 they have a certain degree of stability in time; 3 they tend to alternate so that the dissolution of one is rapidly followed by the emergence of another; 4 they can be described in qualitative terms according to the nature of the emotional mix that dominates the state, in structural terms by a kind of typical 'leadership’ pattern, and in 'cognitive’ terms by a set of implicit expectations that are helpful in explaining the group behavior (i.e. the group behaves 'as if’ it was assuming that…. Here we adopt a formal approach derived from Socio-physics in order to explore some of the structural and dynamic properties of this small group dynamics. We will described data from an analytic DS model simulating small group interactions of agents endowed with a very simplified emotional and cognitive dynamic in order to assess the following main points: 1 are metastable collective states allowed to emerge in the model and if so, under which conditions in the parameter space? 3 can these states be differentiated in structural terms? 3 to what extent are the emergent dynamic features of the systems dependent of the system size? We will finally discuss possible future applications of the quantitative descriptions of the interaction structure in the small group clinical
The Effects of Interference Suppression by a Reconfigurable Structure at DSSS-DPSK Receiver
Directory of Open Access Journals (Sweden)
B. Dimitrijevic
2010-12-01
Full Text Available In this paper we show the performances of DSSS-DPSK receiver where the interference rejection circuit is reconfigurable and is using ksi-structure. The results will be shown for the case of packet, as well as for the continuous QPSK interference. The results show that the proposed reconfiguration circuit, in case of packet QPSK interference, significantly decreases the error probability, compared to the system using only ksi-structure. Also, in case of continuous interference, the reconfigurable structure has equally good performance, regardless of interference power and its bitrate.
Sukhodolov, Alexander N.; Krick, Julian; Sukhodolova, Tatiana A.; Cheng, Zhengyang; Rhoads, Bruce L.; Constantinescu, George S.
2017-06-01
Only a handful of field studies have examined turbulent flow structure at discordant confluences; the dynamics of flow at such confluences have mainly been examined in the laboratory. This paper reports results of a field-based investigation of turbulent flow structure at a discordant river confluence. These results support the hypothesis that flow at a discordant alluvial confluence with a velocity ratio greater than 2 exhibits jet-like characteristics. Scaling analysis shows that the dynamics of the jet core are quite similar to those of free jets but that the complex structure of flow at the confluence imposes strong effects that can locally suppress or enhance the spreading rate of the jet. This jet-like behavior of the flow has important implications for morphodynamic processes at these types of confluences. The highly energetic core of the jet at this discordant confluence is displaced away from the riverbed, thereby inhibiting scour; however, helical motion develops adjacent to the jet, particularly at high flows, which may promote scour. Numerical experiments demonstrate that the presence or absence of a depositional wedge at the mouth of the tributary can strongly influence detachment of the jet from the bed and the angle of the jet within the confluence.
Structure and dynamics of thylakoids in land plants
DEFF Research Database (Denmark)
Pribil, Mathias; Labs, Mathias; Leister, Dario
2014-01-01
Thylakoids of land plants have a bipartite structure, consisting of cylindrical grana stacks, made of membranous discs piled one on top of the other, and stroma lamellae which are helically wound around the cylinders. Protein complexes predominantly located in the stroma lamellae and grana end....... Depending on light conditions, thylakoid membranes undergo dynamic structural changes that involve alterations in granum diameter and height, vertical unstacking of grana, and swelling of the thylakoid lumen. This plasticity is realized predominantly by reorganization of the supramolecular structure...
Safdernejad, Morteza S.; Karpenko, Oleksii; Ye, Chaofeng; Udpa, Lalita; Udpa, Satish
2016-02-01
The advent of Giant Magneto-Resistive (GMR) technology permits development of novel highly sensitive array probes for Eddy Current (EC) inspection of multi-layer riveted structures. Multi-frequency GMR measurements with different EC pene-tration depths show promise for detection of bottom layer notches at fastener sites. However, the distortion of the induced magnetic field due to flaws is dominated by the strong fastener signal, which makes defect detection and classification a challenging prob-lem. This issue is more pronounced for ferromagnetic fasteners that concentrate most of the magnetic flux. In the present work, a novel multi-frequency mixing algorithm is proposed to suppress rivet signal response and enhance defect detection capability of the GMR array probe. The algorithm is baseline-free and does not require any assumptions about the sample geometry being inspected. Fastener signal suppression is based upon the random sample consensus (RANSAC) method, which iteratively estimates parameters of a mathematical model from a set of observed data with outliers. Bottom layer defects at fastener site are simulated as EDM notches of different length. Performance of the proposed multi-frequency mixing approach is evaluated on finite element data and experimental GMR measurements obtained with unidirectional planar current excitation. Initial results are promising demonstrating the feasibility of the approach.
Petersen, Maya L; Wang, Yue; van der Laan, Mark J; Guzman, David; Riley, Elise; Bangsberg, David R
2007-10-01
Pillbox organizers are inexpensive and easily used; however, their effect on adherence to antiretroviral medications is unknown. Data were obtained from an observational cohort of 245 human immunodeficiency virus (HIV)-infected subjects who were observed from 1996 through 2000 in San Francisco, California. Adherence was the primary outcome and was measured using unannounced monthly pill counts. Plasma HIV RNA level was considered as a secondary outcome. Marginal structural models were used to estimate the effect of pillbox organizer use on adherence and viral suppression, adjusting for confounding by CD4+ T cell count, viral load, prior adherence, recreational drug use, demographic characteristics, and current and past treatment. Pillbox organizer use was estimated to improve adherence by 4.1%-4.5% and was associated with a decrease in viral load of 0.34-0.37 log10 copies/mL and a 14.2%-15.7% higher probability of achieving a viral load organizers appear to significantly improve adherence to antiretroviral therapy and to improve virologic suppression. We estimate that pillbox organizers may be associated with a cost of approximately $19,000 per quality-adjusted life-year. Pillbox organizers should be a standard intervention to improve adherence to antiretroviral therapy.
Kato, Tatsuya; Kikuta, Kotaro; Kanematsu, Ayumi; Kondo, Sachiko; Yagi, Hirokazu; Kato, Koichi; Park, Enoch Y
2017-09-01
To synthesize complex type N-glycans in silkworms, shRNAs against the fused lobe from Bombyx mori (BmFDL), which codes N-acetylglucosaminidase (GlcNAcase) in the Golgi, was expressed by recombinant B. mori nucleopolyhedrovirus (BmNPV) in silkworm larvae. Expression was under the control of the actin promoter of B. mori or the U6-2 and i.e.-2 promoters from Orgyia pseudotsugata multiple nucleopolyhedrovirus (OpMNPV). The reduction of specific GlcNAcase activity was observed in Bm5 cells and silkworm larvae using the U6-2 promoter. In silkworm larvae, the partial suppression of BmFDL gene expression was observed. When shRNA against BmFDL was expressed under the control of U6-2 promoter, the Man 3 GlcNAc(Fuc)GlcNAc structure appeared in a main N-glycans of recombinant human IgG. These results suggested that the control of BmFDL expression by its shRNA in silkworms caused the modification of its N-glycan synthetic pathway, which may lead to the alteration of N-glycans in the expressed recombinant proteins. Suppression of BmFDL gene expression by shRNA is not sufficient to synthesize complex N-glycans in silkworm larvae but can modify the N-glycan synthetic pathway.
Dynamic vortex dust structures in a nuclear-track plasma
International Nuclear Information System (INIS)
Rykov, V A; Khudyakov, A V; Filinov, V S; Vladimirov, V I; Deputatova, L V; Krutov, D V; Fortov, V E
2003-01-01
Results are presented from Monte Carlo calculations of the electric charge on dust grains in a plasma produced during the slowing down of radioactive decay products of californium nuclei in neon. The dust grain charging is explained as being due to the drift of electrons and ions in an external electric field. It is shown that the charges of the grains depend on their coordinates and strongly fluctuate with time. The time-averaged grain charges agree with the experimental data obtained on ordered liquid-like dust structures in a nuclear-track plasma. The time-averaged dust grain charges are used to carry out computer modelling of the formation of dynamic vortex structures observed in experiments. Evidence is obtained for the fact that the electrostatic forces experienced by the dust grains are potential in character. The paper is supplemented by a video clip showing the typical dynamics of the simulated vortex dust structure
Applications of Asymptotic Sampling on High Dimensional Structural Dynamic Problems
DEFF Research Database (Denmark)
Sichani, Mahdi Teimouri; Nielsen, Søren R.K.; Bucher, Christian
2011-01-01
The paper represents application of the asymptotic sampling on various structural models subjected to random excitations. A detailed study on the effect of different distributions of the so-called support points is performed. This study shows that the distribution of the support points has consid...... dimensional reliability problems in structural dynamics.......The paper represents application of the asymptotic sampling on various structural models subjected to random excitations. A detailed study on the effect of different distributions of the so-called support points is performed. This study shows that the distribution of the support points has...... is minimized. Next, the method is applied on different cases of linear and nonlinear systems with a large number of random variables representing the dynamic excitation. The results show that asymptotic sampling is capable of providing good approximations of low failure probability events for very high...
Modeling structural change in spatial system dynamics: A Daisyworld example.
Neuwirth, C; Peck, A; Simonović, S P
2015-03-01
System dynamics (SD) is an effective approach for helping reveal the temporal behavior of complex systems. Although there have been recent developments in expanding SD to include systems' spatial dependencies, most applications have been restricted to the simulation of diffusion processes; this is especially true for models on structural change (e.g. LULC modeling). To address this shortcoming, a Python program is proposed to tightly couple SD software to a Geographic Information System (GIS). The approach provides the required capacities for handling bidirectional and synchronized interactions of operations between SD and GIS. In order to illustrate the concept and the techniques proposed for simulating structural changes, a fictitious environment called Daisyworld has been recreated in a spatial system dynamics (SSD) environment. The comparison of spatial and non-spatial simulations emphasizes the importance of considering spatio-temporal feedbacks. Finally, practical applications of structural change models in agriculture and disaster management are proposed.
Directory of Open Access Journals (Sweden)
Sanaz Mahmoudpour
2011-01-01
Full Text Available Analysis and design of structures subjected to arbitrary dynamic loadings especially earthquakes have been studied during past decades. In practice, the effects of soil-structure interaction on the dynamic response of structures are usually neglected. In this study, the effect of soil-structure interaction on the dynamic response of structures has been examined. The substructure method using dynamic stiffness of soil is used to analyze soil-structure system. A coupled model based on finite element method and scaled boundary finite element method is applied. Finite element method is used to analyze the structure, and scaled boundary finite element method is applied in the analysis of unbounded soil region. Due to analytical solution in the radial direction, the radiation condition is satisfied exactly. The material behavior of soil and structure is assumed to be linear. The soil region is considered as a homogeneous half-space. The analysis is performed in time domain. A computer program is prepared to analyze the soil-structure system. Comparing the results with those in literature shows the exactness and competency of the proposed method.
Uncertainty propagation through dynamic models of assemblies of mechanical structures
International Nuclear Information System (INIS)
Daouk, Sami
2016-01-01
When studying the behaviour of mechanical systems, mathematical models and structural parameters are usually considered deterministic. Return on experience shows however that these elements are uncertain in most cases, due to natural variability or lack of knowledge. Therefore, quantifying the quality and reliability of the numerical model of an industrial assembly remains a major question in low-frequency dynamics. The purpose of this thesis is to improve the vibratory design of bolted assemblies through setting up a dynamic connector model that takes account of different types and sources of uncertainty on stiffness parameters, in a simple, efficient and exploitable in industrial context. This work has been carried out in the framework of the SICODYN project, led by EDF R and D, that aims to characterise and quantify, numerically and experimentally, the uncertainties in the dynamic behaviour of bolted industrial assemblies. Comparative studies of several numerical methods of uncertainty propagation demonstrate the advantage of using the Lack-Of-Knowledge theory. An experimental characterisation of uncertainties in bolted structures is performed on a dynamic test rig and on an industrial assembly. The propagation of many small and large uncertainties through different dynamic models of mechanical assemblies leads to the assessment of the efficiency of the Lack-Of-Knowledge theory and its applicability in an industrial environment. (author)
Pleil, Joachim D; Stiegel, Matthew A; Fent, Kenneth W
2014-09-01
Firefighters wear fireproof clothing and self-contained breathing apparatus (SCBA) during rescue and fire suppression activities to protect against acute effects from heat and toxic chemicals. Fire services are also concerned about long-term health outcomes from chemical exposures over a working lifetime, in particular about low-level exposures that might serve as initiating events for adverse outcome pathways (AOP) leading to cancer. As part of a larger US National Institute for Occupational Safety and Health (NIOSH) study of dermal exposure protection from safety gear used by the City of Chicago firefighters, we collected pre- and post-fire fighting breath samples and analyzed for single-ring and polycyclic aromatic hydrocarbons as bioindicators of occupational exposure to gas-phase toxicants. Under the assumption that SCBA protects completely against inhalation exposures, any changes in the exhaled profile of combustion products were attributed to dermal exposures from gas and particle penetration through the protective clothing. Two separate rounds of firefighting activity were performed each with 15 firefighters per round. Exhaled breath samples were collected onto adsorbent tubes and analyzed with gas-chromatography-mass spectrometry (GC-MS) with a targeted approach using selective ion monitoring. We found that single ring aromatics and some PAHs were statistically elevated in post-firefighting samples of some individuals, suggesting that fire protective gear may allow for dermal exposures to airborne contaminants. However, in comparison to a previous occupational study of Air Force maintenance personnel where similar compounds were measured, these exposures are much lower suggesting that firefighters' gear is very effective. This study suggests that exhaled breath sampling and analysis for specific targeted compounds is a suitable method for assessing systemic dermal exposure in a simple and non-invasive manner.
Directory of Open Access Journals (Sweden)
Takamatsu Kiyoharu
2010-07-01
Full Text Available Abstract Background Dietary 1(3-behenoyl-2,3(1-dioleoyl-rac-glycerol (BOO has been reported to inhibit pancreatic lipase activity in vitro and suppress postprandial hypertriacylglycerolemia in humans. In the present study, the anti-obesity activities of BOO and its inhibitory effects on lymphatic triacylglycerol (TAG absorption were investigated in rats. Methods In Experiment 1, rats were fed either BOO or soybean oil (SO diet for 6 weeks. In the BOO diet, 20% of SO was replaced with an experimental oil rich in BOO. In Experiments 2 and 3, rats cannulated in the thoracic duct were administered an emulsions containing trioleoylglycerol (OOO or an oil mixture (OOO:BOO, 9:1. Tri[1-14C]oleoylglycerol (14C-OOO was added to the emulsions administered in Experiment 3. Results No observable differences were detected in food intake or body weight gain between the BOO and SO groups in Experiment 1. Plasma and liver TAG concentrations and visceral fat weights were significantly lower in the BOO group than in the SO group. The apparent absorption rate of fat was significantly lower in the BOO group than in the SO group. In Experiment 2, the lymphatic recovery of oleic and behenic acids was significantly lower at 5 and 6 h after BOO administration than after OOO administration. In Experiment 3, the lymphatic recovery of 14C-OOO was significantly lower at 5 and 6 h after BOO administration than after OOO administration. Conclusions These results suggest that BOO prevents deposition of visceral fat and hepatic TAG by lowering and delaying intestinal absorption of TAG.
Solution structure and dynamics of melanoma inhibitory activity protein
International Nuclear Information System (INIS)
Lougheed, Julie C.; Domaille, Peter J.; Handel, Tracy M.
2002-01-01
Melanoma inhibitory activity (MIA) is a small secreted protein that is implicated in cartilage cell maintenance and melanoma metastasis. It is representative of a recently discovered family of proteins that contain a Src Homologous 3 (SH3) subdomain. While SH3 domains are normally found in intracellular proteins and mediate protein-protein interactions via recognition of polyproline helices, MIA is single-domain extracellular protein, and it probably binds to a different class of ligands.Here we report the assignments, solution structure, and dynamics of human MIA determined by heteronuclear NMR methods. The structures were calculated in a semi-automated manner without manual assignment of NOE crosspeaks, and have a backbone rmsd of 0.38 A over the ordered regions of the protein. The structure consists of an SH3-like subdomain with N- and C-terminal extensions of approximately 20 amino acids each that together form a novel fold. The rmsd between the solution structure and our recently reported crystal structure is 0.86 A over the ordered regions of the backbone, and the main differences are localized to the most dynamic regions of the protein. The similarity between the NMR and crystal structures supports the use of automated NOE assignments and ambiguous restraints to accelerate the calculation of NMR structures
International Nuclear Information System (INIS)
Stefanou, Stefanos
2002-07-01
Substrate crosstalk or coupling has been acknowledged to be a limiting factor in mixed signal RF integration. Although high levels of integration and high frequencies of operation are desirable for mixed mode RF and microwave circuits, they make substrate crosstalk more pronounced and may lead to circuit performance degradation. High signal isolation is dictated by requirements for low power dissipation, reduced number of components and lower integration costs for feasible system-on-chip (SoC) solutions. Substrate crosstalk suppression in ground plane silicon-on-insulator (GPSOI) substrates is investigated in this thesis. Test structures are designed and fabricated on SOI substrates with a buried WSi 2 plane that is connected to ground; hence it is called a ground plane. A Faraday cage structure that exhibits very high degrees of signal isolation is presented and compared to other SOI isolation schemes. The Faraday cage structure is shown to achieve 20 dB increased isolation in the frequency range of 0.5-50 GHz compared to published data for high resistivity (200 Ωcm) thin film SOI substrates with no ground planes, but where capacitive guard rings were used. The measurement results are analysed with the aid of planar electromagnetic simulators and compact lumped element models of all the fabricated test structures are developed. The accuracy of the lumped models is validated against experimental measurements. (author)
Structure, entanglements and dynamics of polymer nanocomposites containing spherical nanoparticles
International Nuclear Information System (INIS)
Karatrantos, A; Clarke, N; Composto, R J; Winey, K I
2014-01-01
We investigate the effect of nanoparticles on polymer structure, nanoparticle dynamics and topological constraints (entanglements) in polymer melts for nanoparticle loading above percolation threshold as high as 40.9% using stochastic molecular dynamics (MD) simulations. An increase in the number of entanglements (decrease of N e with 40.9% volume fraction of nanoparticles dispersed in the polymer matrix) in the nanocomposites is observed as evidenced by larger contour lengths of the primitive paths. Attraction between polymers and nanoparticles affects the entanglements in the nanocomposites and alters the primitive path. The diffusivity of small sized nanoparticles deviates significantly from the Stokes- Einstein relation
Coalescence of silver unidimensional structures by molecular dynamics simulation
International Nuclear Information System (INIS)
Perez A, M.; Gutierrez W, C.E.; Mondragon, G.; Arenas, J.
2007-01-01
The study of nanoparticles coalescence and silver nano rods phenomena by means of molecular dynamics simulation under the thermodynamic laws is reported. In this work we focus ourselves to see the conditions under which the one can be given one dimension growth of silver nano rods for the coalescence phenomenon among two nano rods or one nano rod and one particle; what allows us to study those structural, dynamic and morphological properties of the silver nano rods to different thermodynamic conditions. The simulations are carried out using the Sutton-Chen potentials of interaction of many bodies that allow to obtain appropriate results with the real physical systems. (Author)
An age-structured population balance model for microbial dynamics
Directory of Open Access Journals (Sweden)
Duarte M.V.E.
2003-01-01
Full Text Available This work presents an age-structured population balance model (ASPBM for a bioprocess in a continuous stirred-tank fermentor. It relates the macroscopic properties and dynamic behavior of biomass to the operational parameters and microscopic properties of cells. Population dynamics is governed by two time- and age-dependent density functions for living and dead cells, accounting for the influence of substrate and dissolved oxygen concentrations on cell division, aging and death processes. The ASPBM described biomass and substrate oscillations in aerobic continuous cultures as experimentally observed. It is noteworthy that a small data set consisting of nonsegregated measurements was sufficient to adjust a complex segregated mathematical model.
Estimating spatio-temporal dynamics of size-structured populations
DEFF Research Database (Denmark)
Kristensen, Kasper; Thygesen, Uffe Høgsbro; Andersen, Ken Haste
2014-01-01
with simple stock dynamics, to estimate simultaneously how size distributions and spatial distributions develop in time. We demonstrate the method for a cod population sampled by trawl surveys. Particular attention is paid to correlation between size classes within each trawl haul due to clustering...... of individuals with similar size. The model estimates growth, mortality and reproduction, after which any aspect of size-structure, spatio-temporal population dynamics, as well as the sampling process can be probed. This is illustrated by two applications: 1) tracking the spatial movements of a single cohort...
Directory of Open Access Journals (Sweden)
Lana Damaj
2015-01-01
Full Text Available A wideband dual-polarized coplanar waveguide (CPW fed antenna integrating a wide stop-band filter is presented. The designed filter is based on a nonuniform defected ground structure (DGS in order to obtain a wide stop-band and a compact size. This filter is used to reject harmonics and spurious radiation arising from the RF front end. The complete structure (antenna and filter has been optimized to have a compact size of 0.6×0.6λ02 (λ0 being the free-space wavelength at the lowest operating frequency. The realized antenna operates in the frequency range between 2.7 GHz and 5.9 GHz (bandwidth of about 74%. The isolation between feeding ports is more than 18 dB. The complete structure has a wide stop-band characteristic (103% for harmonic rejection. The simulated numerical results have been confirmed with measurements.
Allison, Jane R; Hertig, Samuel; Missimer, John H; Smith, Lorna J; Steinmetz, Michel O; Dolenc, Jožica
2012-10-09
NMR experiments provide detailed structural information about biological macromolecules in solution. However, the amount of information obtained is usually much less than the number of degrees of freedom of the macromolecule. Moreover, the relationships between experimental observables and structural information, such as interatomic distances or dihedral angle values, may be multiple-valued and may rely on empirical parameters and approximations. The extraction of structural information from experimental data is further complicated by the time- and ensemble-averaged nature of NMR observables. Combining NMR data with molecular dynamics simulations can elucidate and alleviate some of these problems, as well as allow inconsistencies in the NMR data to be identified. Here, we use a number of examples from our work to highlight the power of molecular dynamics simulations in providing a structural interpretation of solution NMR data.
The structure and dynamics of patterns of Benard convection cells
International Nuclear Information System (INIS)
Rivier, N.; Imperial Coll. of Science and Technology, London; Lausanne Univ.
1990-08-01
Benard-Marangoni convection, in containers with large aspect ratio, exhibits space-filling cellular structures, highly deformable, but crystallized. They contain dislocations and grain boundaries generated and moved by elementary topological transformations, and are subjected to a weak shear stress due to the earth's rotation. The cellular structure and its fluctuations are analyzed from a crystallographic viewpoint, by using two complementary approaches. One is a global analysis of cellular structures in cylindrical symmetry. Their structural stability and defect pattern are obtained as topological mode-locking of a continuous structural parameter. The other, a local, molecular dynamics of the cells, gives a realistic parametrization of the forces and the transformations by generalizing the Voronoi cell construction in one extra dimension. 23 refs., 8 figs
Energy Technology Data Exchange (ETDEWEB)
Liu, Po-Tsun, E-mail: ptliu@mail.nctu.edu.tw; Chang, Chih-Hsiang; Chang, Chih-Jui [Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan (China)
2016-06-27
This study investigates the instability induced by bias temperature illumination stress (NBTIS) for an amorphous indium-tungsten-oxide thin film transistor (a-IWO TFT) with SiO{sub 2} backchannel passivation layer (BPL). It is found that this electrical degradation phenomenon can be attributed to the generation of defect states during the BPL process, which deteriorates the photo-bias stability of a-IWO TFTs. A method proposed by adding an oxygen-rich a-IWO thin film upon the a-IWO active channel layer could effectively suppress the plasma damage to channel layer during BPL deposition process. The bi-layer a-IWO TFT structure with an oxygen-rich back channel exhibits superior electrical reliability of device under NBTIS.
Choi, Seungbeom; Jo, Jeong-Wan; Kim, Jaeyoung; Song, Seungho; Kim, Jaekyun; Park, Sung Kyu; Kim, Yong-Hoon
2017-08-09
Here, we report static and dynamic water motion-induced instability in indium-gallium-zinc-oxide (IGZO) thin-film transistors (TFTs) and its effective suppression with the use of a simple, solution-processed low-k (ε ∼ 1.9) fluoroplastic resin (FPR) passivation layer. The liquid-contact electrification effect, in which an undesirable drain current modulation is induced by a dynamic motion of a charged liquid such as water, can cause a significant instability in IGZO TFTs. It was found that by adopting a thin (∼44 nm) FPR passivation layer for IGZO TFTs, the current modulation induced by the water-contact electrification was greatly reduced in both off- and on-states of the device. In addition, the FPR-passivated IGZO TFTs exhibited an excellent stability to static water exposure (a threshold voltage shift of +0.8 V upon 3600 s of water soaking), which is attributed to the hydrophobicity of the FPR passivation layer. Here, we discuss the origin of the current instability caused by the liquid-contact electrification as well as various static and dynamic stability tests for IGZO TFTs. On the basis of our findings, we believe that the use of a thin, solution-processed FPR passivation layer is effective in suppressing the static and dynamic water motion-induced instabilities, which may enable the realization of high-performance and environment-stable oxide TFTs for emerging wearable and skin-like electronics.
MIIP remodels Rac1-mediated cytoskeleton structure in suppression of endometrial cancer metastasis
Directory of Open Access Journals (Sweden)
Yingmei Wang
2016-10-01
Full Text Available Abstract Background Endometrial carcinoma (EC is one of the most common malignancies of the female reproductive system. Migration and invasion inhibitory protein (MIIP gene was recently discovered candidate tumor suppress gene which located at chromosome 1p36.22. 1p36 deletion was found in many types of tumor including EC. In the present study, we will determine the role and mechanism of MIIP in EC metastasis. Methods Immunohistochemistry was used to measure MIIP expression in normal and EC tissue. Both gain-of-function (infection and loss-of-function (siRNA assays were used to alter MIIP expression levels. The effect of MIIP on cell migration and invasion was measured by transwell assay. F-actin immunofluorescence staining was used to observe the cell morphology. The activation of GTP-loaded Rac1 was evaluated by Rac activity assay kit. Immunoprecipitation/WB was used to measure the interaction between MIIP and PAK1. Results We demonstrate that MIIP expression was significantly decreased in EC patients comparing to the normal ones, and decreased MIIP expression in EC tissues is associated with deep myometrial invasion, advanced stage, and the presence of lymph node metastasis. Using both gain-of-function (infection and loss-of-function (siRNA assays, we show that MIIP markedly blocked EC cell migration, whereas loss of MIIP led to increase in EC cell migration. We demonstrate that elevated expression of MIIP resulted in cytoskeleton reorganization with decreased formation of lamellipodia. We also provide evidence that MIIP is a key molecule in directing Rac1 signaling cascades in EC. Ectopically expressed MIIP consistently competed with Rac1-GTP for binding with the PAK1 p21-binding domain. Our data show that MIIP and PAK1 bind each other and that a C-terminal polyproline domain of MIIP is required for PAK1 binding. Deletion of the PAK1-binding domain of MIIP reduced cell migration-inhibiting activity. Conclusions MIIP may function as a tumor
MIIP remodels Rac1-mediated cytoskeleton structure in suppression of endometrial cancer metastasis.
Wang, Yingmei; Hu, Limei; Ji, Ping; Teng, Fei; Tian, Wenyan; Liu, Yuexin; Cogdell, David; Liu, Jinsong; Sood, Anil K; Broaddus, Russell; Xue, Fengxia; Zhang, Wei
2016-10-19
Endometrial carcinoma (EC) is one of the most common malignancies of the female reproductive system. Migration and invasion inhibitory protein (MIIP) gene was recently discovered candidate tumor suppress gene which located at chromosome 1p36.22. 1p36 deletion was found in many types of tumor including EC. In the present study, we will determine the role and mechanism of MIIP in EC metastasis. Immunohistochemistry was used to measure MIIP expression in normal and EC tissue. Both gain-of-function (infection) and loss-of-function (siRNA) assays were used to alter MIIP expression levels. The effect of MIIP on cell migration and invasion was measured by transwell assay. F-actin immunofluorescence staining was used to observe the cell morphology. The activation of GTP-loaded Rac1 was evaluated by Rac activity assay kit. Immunoprecipitation/WB was used to measure the interaction between MIIP and PAK1. We demonstrate that MIIP expression was significantly decreased in EC patients comparing to the normal ones, and decreased MIIP expression in EC tissues is associated with deep myometrial invasion, advanced stage, and the presence of lymph node metastasis. Using both gain-of-function (infection) and loss-of-function (siRNA) assays, we show that MIIP markedly blocked EC cell migration, whereas loss of MIIP led to increase in EC cell migration. We demonstrate that elevated expression of MIIP resulted in cytoskeleton reorganization with decreased formation of lamellipodia. We also provide evidence that MIIP is a key molecule in directing Rac1 signaling cascades in EC. Ectopically expressed MIIP consistently competed with Rac1-GTP for binding with the PAK1 p21-binding domain. Our data show that MIIP and PAK1 bind each other and that a C-terminal polyproline domain of MIIP is required for PAK1 binding. Deletion of the PAK1-binding domain of MIIP reduced cell migration-inhibiting activity. MIIP may function as a tumor suppressor gene for endometrial carcinoma. MIIP attenuates Rac1
DEFF Research Database (Denmark)
Yang, Tiankui; Fruekilde, Maj-Britt; Xu, Xuebing
2005-01-01
Acyl migration in the glycerol backbone often leads to the increase of by-products in the enzymatic production of specific structured lipids. Acyl migration is a thermodynamic process and is very difficult to stop fully in actual reactions. The objective of this study was to investigate...
Structure and dynamics of a silica melt in neutral confinement
Geske, Julian; Drossel, Barbara; Vogel, Michael
2017-04-01
We analyze the effects of spatial confinement on viscous silica using molecular dynamics simulations. For this purpose, we prepare a silica melt in a cylindrical pore, which is produced by pinning appropriate fractions of silicon and oxygen atoms in a bulk system after an equilibration period. In this way, the structure of the confined silica melt remains unaffected, while the confinement has a strong impact on the dynamics. We find that the structural relaxation of viscous silica is slowed down according to a double exponential law when approaching the pore wall. Moreover, we observe that static density correlations exist in the vicinity of the pore wall. Based on these effects, we determine dynamical and structural length scales of the silica melt. Both length scales show a similar increase upon cooling, with values on the order of the next-neighbor distances in the studied temperature range. Interestingly, we find no evidence that the growth of the length scales is affected by a fragile-to-strong transition of the silica melt. This observation casts serious doubts on the relevance of these length scales for the structural relaxation, at least for the studied glass former.
Dynamic testing of MFTF containment-vessel structural system
International Nuclear Information System (INIS)
Weaver, H.J.; McCallen, D.B.; Eli, M.W.
1982-01-01
Dynamic (modal) testing was performed on the Magnetic Fusion Test Facility (MFTF) containment vessel. The seismic design of this vessel was heavily dependent upon the value of structural damping used in the analysis. Typically for welded steel vessels, a value of 2 to 3% of critical is used. However, due to the large mass of the vessel and magnet supported inside, we felt that the interaction between the structure and its foundation would be enhanced. This would result in a larger value of damping because vibrational energy in the structure would be transferred through the foundation into the surrounding soil. The dynamic test performed on this structure (with the magnet in place) confirmed this later theory and resulted in damping values of approximately 4 to 5% for the whole body modes. This report presents a brief description of dynamic testing emphasizing the specific test procedure used on the MFTF-A system. It also presents an interpretation of the damping mechanisms observed (material and geometric) based upon the spatial characteristics of the modal parameters
Structural fluctuation governed dynamic diradical character in pentacene.
Yang, Hongfang; Chen, Mengzhen; Song, Xinyu; Bu, Yuxiang
2015-06-07
We unravel intriguing dynamical diradical behavior governed by structural fluctuation in pentacene using ab initio molecular dynamics simulation. In contrast to static equilibrium configuration of pentacene with a closed-shell ground state without diradical character, due to structural fluctuation, some of its dynamical snapshot configurations exhibit an open-shell broken-symmetry singlet ground state with diradical character, and such diradical character presents irregular pulsing behavior in time evolution. Not all structural changes can lead to diradical character, only those involving the shortening of cross-linking C-C bonds and variations of the C-C bonds in polyacetylene chains are the main contributors. This scenario about diradicalization is distinctly different from that in long acenes. The essence is that structural distortion cooperatively raises the HOMO and lowers the LUMO, efficiently reducing the HOMO-LUMO and singlet-triplet energy gaps, which facilitate the formation of a broken-symmetry open-shell singlet state. The irregular pulsing behavior originates from the mixing of normal vibrations in pentacene. This fascinating behavior suggests the potential application of pentacene as a suitable building block in the design of new electronic devices due to its magnetism-controllability through energy induction. This work provides new insight into inherent electronic property fluctuation in acenes.
Abramov, Rafail V.
2011-01-01
Chaotic multiscale dynamical systems are common in many areas of science, one of the examples being the interaction of the low-frequency dynamics in the atmosphere with the fast turbulent weather dynamics. One of the key questions about chaotic multiscale systems is how the fast dynamics affects chaos at the slow variables, and, therefore, impacts uncertainty and predictability of the slow dynamics. Here we demonstrate that the linear slow-fast coupling with the total energy conservation prop...
Dynamic Analysis of Wind Turbines Including Soil-Structure Interaction
DEFF Research Database (Denmark)
Harte, M.; Basu, B.; Nielsen, Søren R.K.
2012-01-01
This paper investigates the along-wind forced vibration response of an onshore wind turbine. The study includes the dynamic interaction effects between the foundation and the underlying soil, as softer soils can influence the dynamic response of wind turbines. A Multi-Degree-of-Freedom (MDOF......) horizontal axes onshore wind turbine model is developed for dynamic analysis using an Euler–Lagrangian approach. The model is comprised of a rotor blade system, a nacelle and a flexible tower connected to a foundation system using a substructuring approach. The rotor blade system consists of three rotating...... for displacement of the turbine system are obtained and the modal frequencies of the combined turbine-foundation system are estimated. Simulations are presented for the MDOF turbine structure subjected to wind loading for different soil stiffness conditions. Steady state and turbulent wind loading, developed using...
IUTAM Symposium on Hamiltonian Dynamics, Vortex Structures, Turbulence
Borisov, Alexey V; Mamaev, Ivan S; Sokolovskiy, Mikhail A; IUTAM BOOKSERIES : Volume 6
2008-01-01
This work brings together previously unpublished notes contributed by participants of the IUTAM Symposium on Hamiltonian Dynamics, Vortex Structures, Turbulence (Moscow, 25-30 August 2006). The study of vortex motion is of great interest to fluid and gas dynamics: since all real flows are vortical in nature, applications of the vortex theory are extremely diverse, many of them (e.g. aircraft dynamics, atmospheric and ocean phenomena) being especially important. The last few decades have shown that serious possibilities for progress in the research of real turbulent vortex motions are essentially related to the combined use of mathematical methods, computer simulation and laboratory experiments. These approaches have led to a series of interesting results which allow us to study these processes from new perspectives. Based on this principle, the papers collected in this proceedings volume present new results on theoretical and applied aspects of the processes of formation and evolution of various flows, wave a...
Population and evolutionary dynamics in spatially structured seasonally varying environments.
Reid, Jane M; Travis, Justin M J; Daunt, Francis; Burthe, Sarah J; Wanless, Sarah; Dytham, Calvin
2018-03-25
Increasingly imperative objectives in ecology are to understand and forecast population dynamic and evolutionary responses to seasonal environmental variation and change. Such population and evolutionary dynamics result from immediate and lagged responses of all key life-history traits, and resulting demographic rates that affect population growth rate, to seasonal environmental conditions and population density. However, existing population dynamic and eco-evolutionary theory and models have not yet fully encompassed within-individual and among-individual variation, covariation, structure and heterogeneity, and ongoing evolution, in a critical life-history trait that allows individuals to respond to seasonal environmental conditions: seasonal migration. Meanwhile, empirical studies aided by new animal-tracking technologies are increasingly demonstrating substantial within-population variation in the occurrence and form of migration versus year-round residence, generating diverse forms of 'partial migration' spanning diverse species, habitats and spatial scales. Such partially migratory systems form a continuum between the extreme scenarios of full migration and full year-round residence, and are commonplace in nature. Here, we first review basic scenarios of partial migration and associated models designed to identify conditions that facilitate the maintenance of migratory polymorphism. We highlight that such models have been fundamental to the development of partial migration theory, but are spatially and demographically simplistic compared to the rich bodies of population dynamic theory and models that consider spatially structured populations with dispersal but no migration, or consider populations experiencing strong seasonality and full obligate migration. Second, to provide an overarching conceptual framework for spatio-temporal population dynamics, we define a 'partially migratory meta-population' system as a spatially structured set of locations that can
A Novel Double-Piston Magnetorheological Damper for Space Truss Structures Vibration Suppression
Qiang Wang; Mehdi Ahmadian; Zhaobo Chen
2014-01-01
The design, fabrication, and testing of a new double-piston MR damper for space applications are discussed. The design concept for the damper is described in detail. The electromagnetic analysis of the design and the fabrication of the MR damper are also presented. The design analysis shows that the damper meets the weight and size requirements for being included in a space truss structure. The prototype design is tested in a damper dynamometer. The test results show that the damper can provi...
Directory of Open Access Journals (Sweden)
Shoshana Y Kahana
Full Text Available The authors examined associations between structural characteristics and HIV disease management among a geographically diverse sample of behaviorally and perinatally HIV-infected adolescents and young adults in the United States.The sample included 1891 adolescents and young adults living with HIV (27.8% perinatally infected; 72.2% behaviorally infected who were linked to care through 20 Adolescent Medicine Trials Network for HIV/AIDS Interventions Units. All completed audio computer-assisted self-interview surveys. Chart abstraction or blood draw provided viral load data. Geographic-level variables were extracted from the United States Census Bureau (e.g., socioeconomic disadvantage, percent of Black and Latino households, percent rural and Esri Crime (e.g., global crime index databases as Zip Code Tabulation Areas. AIDSVu data (e.g., prevalence of HIV among youth were extracted at the county-level. Using HLM v.7, the authors conducted means-as-outcomes random effects multi-level models to examine the association between structural-level and individual-level factors and (1 being on antiretroviral therapy (ART currently; (2 being on ART for at least 6 months; (3 missed HIV care appointments (not having missed any vs. having missed one or more appointments over the past 12 months; and (4 viral suppression (defined by the corresponding assay cutoff for the lower limit of viral load at each participating site which denoted nondetectability vs. detectability.Frequencies for the 4 primary outcomes were as follows: current ART use (n = 1120, 59.23%; ART use for ≥6 months (n = 861, 45.53%; at least one missed HIV care appointment (n = 936, 49.50; and viral suppression (n = 577, 30.51%. After adjusting for individual-level factors, youth living in more disadvantaged areas (defined by a composite score derived from 2010 Census indicators including percent poverty, percent receiving public assistance, percent of female, single-headed households, percent
Energy Technology Data Exchange (ETDEWEB)
Gómez-González, Víctor; Docampo-Álvarez, Borja; Gallego, Luis J.; Varela, Luis M., E-mail: luismiguel.varela@usc.es [Grupo de Nanomateriais e Materia Branda, Departamento de Física da Materia Condensada, Universidade de Santiago de Compostela, Campus Vida s/n, E-15782 Santiago de Compostela (Spain); Cabeza, Oscar [Facultade de Ciencias, Universidade da Coruña, Campus A Zapateira s/n, E-15008 A Coruña (Spain); Fedorov, Maxim [Department of Physics, Scottish University Physics Alliance (SUPA), University of Strathclyde, John Anderson Bldg., 107 Rottenrow East, Glasgow G4 0NG (United Kingdom); Lynden-Bell, Ruth M. [Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW (United Kingdom)
2015-09-28
We report a molecular dynamics study of the structure and single-particle dynamics of mixtures of a protic (ethylammonium nitrate) and an aprotic (1-butyl-3-methylimidazolium hexaflurophosphate [BMIM][PF{sub 6}]) room-temperature ionic liquids doped with magnesium and calcium salts with a common anion at 298.15 K and 1 atm. The solvation of these divalent cations in dense ionic environments is analyzed by means of apparent molar volumes of the mixtures, radial distribution functions, and coordination numbers. For the protic mixtures, the effect of salt concentration on the network of hydrogen bonds is also considered. Moreover, single-particle dynamics of the salt cations is studied by means of their velocity autocorrelation functions and vibrational densities of states, explicitly analyzing the influence of salt concentration, and cation charge and mass on these magnitudes. The effect of the valency of the salt cation on these properties is considered comparing the results with those for the corresponding mixtures with lithium salts. We found that the main structural and dynamic features of the local solvation of divalent cations in ionic liquids are similar to those of monovalent salts, with cations being localized in the polar nanoregions of the bulk mixture coordinated in monodentate and bidentate coordination modes by the [NO{sub 3}]{sup −} and [PF{sub 6}]{sup −} anions. However, stronger electrostatic correlations of these polar nanoregions than in mixtures with salts with monovalent cations are found. The vibrational modes of the ionic liquid (IL) are seen to be scarcely affected by the addition of the salt, and the effect of mass and charge on the vibrational densities of states of the dissolved cations is reported. Cation mass is seen to exert a deeper influence than charge on the low-frequency vibrational spectra, giving a red shift of the vibrational modes and a virtual suppression of the higher energy vibrational modes for the heavier Ca{sup 2
International Nuclear Information System (INIS)
Gómez-González, Víctor; Docampo-Álvarez, Borja; Gallego, Luis J.; Varela, Luis M.; Cabeza, Oscar; Fedorov, Maxim; Lynden-Bell, Ruth M.
2015-01-01
We report a molecular dynamics study of the structure and single-particle dynamics of mixtures of a protic (ethylammonium nitrate) and an aprotic (1-butyl-3-methylimidazolium hexaflurophosphate [BMIM][PF 6 ]) room-temperature ionic liquids doped with magnesium and calcium salts with a common anion at 298.15 K and 1 atm. The solvation of these divalent cations in dense ionic environments is analyzed by means of apparent molar volumes of the mixtures, radial distribution functions, and coordination numbers. For the protic mixtures, the effect of salt concentration on the network of hydrogen bonds is also considered. Moreover, single-particle dynamics of the salt cations is studied by means of their velocity autocorrelation functions and vibrational densities of states, explicitly analyzing the influence of salt concentration, and cation charge and mass on these magnitudes. The effect of the valency of the salt cation on these properties is considered comparing the results with those for the corresponding mixtures with lithium salts. We found that the main structural and dynamic features of the local solvation of divalent cations in ionic liquids are similar to those of monovalent salts, with cations being localized in the polar nanoregions of the bulk mixture coordinated in monodentate and bidentate coordination modes by the [NO 3 ] − and [PF 6 ] − anions. However, stronger electrostatic correlations of these polar nanoregions than in mixtures with salts with monovalent cations are found. The vibrational modes of the ionic liquid (IL) are seen to be scarcely affected by the addition of the salt, and the effect of mass and charge on the vibrational densities of states of the dissolved cations is reported. Cation mass is seen to exert a deeper influence than charge on the low-frequency vibrational spectra, giving a red shift of the vibrational modes and a virtual suppression of the higher energy vibrational modes for the heavier Ca 2+ cations. No qualitative
Energy Technology Data Exchange (ETDEWEB)
Koganezawa, K. [Mitsubishi Atomic Power Industries, Inc., Yokohama (Japan); Kushiyama, M. [Mitsubishi Atomic Power Industries, Inc., Yokohama (Japan); Niikura, S. [Mitsubishi Atomic Power Industries, Inc., Yokohama (Japan); Kudough, F. [Mitsubishi Atomic Power Industries, Inc., Yokohama (Japan); Onozuka, M. [Mitsubishi Heavy Industries Ltd., Yokohama (Japan); Koizumi, K. [Japan Atomic Energy Research Inst., Ibaraki (Japan)
1995-12-31
Transient electromagnetic and dynamic structural analyses of a blanket structure in the fusion experimental reactor (FER) under a plasma disruption event and a vertical displacement event (VDE) have been performed to investigate the dynamic structural characteristics and the feasibility of the structure. Coupling effects between eddy currents and dynamic deflections have also been taken into account in these analyses. In this study, the inboard blanket was employed because of our computer memory limitation. A 1/192 segment model of a full torus was analyzed using the analytical code, EDDYCUFF. In the plasma disruption event, the maximum magnetic pressure caused by eddy currents and poloidal fields was 1.2MPa. The maximum stress intensity by this magnetic pressure was 114MPa. In the VDE, the maximum magnetic pressure was 2.4MPa and the maximum stress intensity was 253MPa. This stress was somewhat beyond the allowable stress limit. Therefore, the blanket structure and support design should be reviewed to reduce the stress to a suitable value. In summary, the dynamic structural characteristics and design issues of the blanket structure have been identified. (orig.).
Excited State Structural Dynamics of Carotenoids and Charge Transfer Systems
International Nuclear Information System (INIS)
Van Tassle, Aaron Justin
2006-01-01
This dissertation describes the development and implementation of a visible/near infrared pump/mid-infrared probe apparatus. Chapter 1 describes the background and motivation of investigating optically induced structural dynamics, paying specific attention to solvation and the excitation selection rules of highly symmetric molecules such as carotenoids. Chapter 2 describes the development and construction of the experimental apparatus used throughout the remainder of this dissertation. Chapter 3 will discuss the investigation of DCM, a laser dye with a fluorescence signal resulting from a charge transfer state. By studying the dynamics of DCM and of its methyl deuterated isotopomer (an otherwise identical molecule), we are able to investigate the origins of the charge transfer state and provide evidence that it is of the controversial twisted intramolecular (TICT) type. Chapter 4 introduces the use of two-photon excitation to the S1 state, combined with one-photon excitation to the S2 state of the carotenoid beta-apo-8'-carotenal. These 2 investigations show evidence for the formation of solitons, previously unobserved in molecular systems and found only in conducting polymers Chapter 5 presents an investigation of the excited state dynamics of peridinin, the carotenoid responsible for the light harvesting of dinoflagellates. This investigation allows for a more detailed understanding of the importance of structural dynamics of carotenoids in light harvesting
Polarizability effects on the structure and dynamics of ionic liquids
Energy Technology Data Exchange (ETDEWEB)
Cavalcante, Ary de Oliveira, E-mail: arycavalcante@ufam.edu.br [Institute of Chemistry, University of Campinas – UNICAMP, Cx. P. 6154, Campinas, SP 13084-862 (Brazil); Departamento de Química, Universidade Federal do Amazonas, Av. Rodrigo Octávio, 6200, Coroado, Manaus, AM (Brazil); Ribeiro, Mauro C. C. [Laboratório de Espectroscopia Molecular, Instituto de Química, Universidade de São Paulo, São Paulo, SP C.P. 26077, 05513 970 São Paulo, SP (Brazil); Skaf, Munir S. [Institute of Chemistry, University of Campinas – UNICAMP, Cx. P. 6154, Campinas, SP 13084-862 (Brazil)
2014-04-14
Polarization effects on the structure and dynamics of ionic liquids are investigated using molecular dynamics simulations. Four different ionic liquids were simulated, formed by the anions Cl{sup −} and PF{sub 6}{sup −}, treated as single fixed charge sites, and the 1-n-alkyl-3-methylimidazolium cations (1-ethyl and 1-butyl-), which are polarizable. The partial charge fluctuation of the cations is provided by the electronegativity equalization model (EEM) and a complete parameter set for the cations electronegativity (χ) and hardness (J) is presented. Results obtained from a non-polarizable model for the cations are also reported for comparison. Relative to the fixed charged model, the equilibrium structure of the first solvation shell around the imidazolium cations shows that inclusion of EEM polarization forces brings cations closer to each other and that anions are preferentially distributed above and below the plane of the imidazolium ring. The polarizable model yields faster translational and reorientational dynamics than the fixed charges model in the rotational-diffusion regime. In this sense, the polarizable model dynamics is in better agreement with the experimental data.
Differentiable dynamical systems an introduction to structural stability and hyperbolicity
Wen, Lan
2016-01-01
This is a graduate text in differentiable dynamical systems. It focuses on structural stability and hyperbolicity, a topic that is central to the field. Starting with the basic concepts of dynamical systems, analyzing the historic systems of the Smale horseshoe, Anosov toral automorphisms, and the solenoid attractor, the book develops the hyperbolic theory first for hyperbolic fixed points and then for general hyperbolic sets. The problems of stable manifolds, structural stability, and shadowing property are investigated, which lead to a highlight of the book, the \\Omega-stability theorem of Smale. While the content is rather standard, a key objective of the book is to present a thorough treatment for some tough material that has remained an obstacle to teaching and learning the subject matter. The treatment is straightforward and hence could be particularly suitable for self-study. Selected solutions are available electronically for instructors only. Please send email to textbooks@ams.org for more informatio...
Ultrafast Dynamic Pressure Sensors Based on Graphene Hybrid Structure.
Liu, Shanbiao; Wu, Xing; Zhang, Dongdong; Guo, Congwei; Wang, Peng; Hu, Weida; Li, Xinming; Zhou, Xiaofeng; Xu, Hejun; Luo, Chen; Zhang, Jian; Chu, Junhao
2017-07-19
Mechanical flexible electronic skin has been focused on sensing various physical parameters, such as pressure and temperature. The studies of material design and array-accessible devices are the building blocks of strain sensors for subtle pressure sensing. Here, we report a new and facile preparation of a graphene hybrid structure with an ultrafast dynamic pressure response. Graphene oxide nanosheets are used as a surfactant to prevent graphene restacking in aqueous solution. This graphene hybrid structure exhibits a frequency-independent pressure resistive sensing property. Exceeding natural skin, such pressure sensors, can provide transient responses from static up to 10 000 Hz dynamic frequencies. Integrated by the controlling system, the array-accessible sensors can manipulate a robot arm and self-rectify the temperature of a heating blanket. This may pave a path toward the future application of graphene-based wearable electronics.
Musical structure analysis using similarity matrix and dynamic programming
Shiu, Yu; Jeong, Hong; Kuo, C.-C. Jay
2005-10-01
Automatic music segmentation and structure analysis from audio waveforms based on a three-level hierarchy is examined in this research, where the three-level hierarchy includes notes, measures and parts. The pitch class profile (PCP) feature is first extracted at the note level. Then, a similarity matrix is constructed at the measure level, where a dynamic time warping (DTW) technique is used to enhance the similarity computation by taking the temporal distortion of similar audio segments into account. By processing the similarity matrix, we can obtain a coarse-grain music segmentation result. Finally, dynamic programming is applied to the coarse-grain segments so that a song can be decomposed into several major parts such as intro, verse, chorus, bridge and outro. The performance of the proposed music structure analysis system is demonstrated for pop and rock music.
Annual Report 2000. Chemical Structure and Dynamics; FINAL
International Nuclear Information System (INIS)
Colson, Steve D; McDowell, Rod S
2001-01-01
This annual report describes the research and accomplishments of the Chemical Structure and Dynamics Program in the year 2000, one of six research programs at the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL) - a multidisciplinary, national scientific user facility and research organization. The Chemical Structure and Dynamics (CS and D) program is meeting the need for a fundamental, molecular-level understanding by (1) extending the experimental characterization and theoretical description of chemical reactions to encompass the effects of condensed media and interfaces; (2) developing a multidisciplinary capability for describing interfacial chemical processes relevant to environmental chemistry; and (3) developing state-of-the-art research and analytical methods for characterizing complex materials of the types found in natural and contaminated systems
Integrative Analysis of Metabolic Models – from Structure to Dynamics
Energy Technology Data Exchange (ETDEWEB)
Hartmann, Anja, E-mail: hartmann@ipk-gatersleben.de [Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben (Germany); Schreiber, Falk [Monash University, Melbourne, VIC (Australia); Martin-Luther-University Halle-Wittenberg, Halle (Germany)
2015-01-26
The characterization of biological systems with respect to their behavior and functionality based on versatile biochemical interactions is a major challenge. To understand these complex mechanisms at systems level modeling approaches are investigated. Different modeling formalisms allow metabolic models to be analyzed depending on the question to be solved, the biochemical knowledge and the availability of experimental data. Here, we describe a method for an integrative analysis of the structure and dynamics represented by qualitative and quantitative metabolic models. Using various formalisms, the metabolic model is analyzed from different perspectives. Determined structural and dynamic properties are visualized in the context of the metabolic model. Interaction techniques allow the exploration and visual analysis thereby leading to a broader understanding of the behavior and functionality of the underlying biological system. The System Biology Metabolic Model Framework (SBM{sup 2} – Framework) implements the developed method and, as an example, is applied for the integrative analysis of the crop plant potato.
A general modeling framework for describing spatially structured population dynamics
Sample, Christine; Fryxell, John; Bieri, Joanna; Federico, Paula; Earl, Julia; Wiederholt, Ruscena; Mattsson, Brady; Flockhart, Tyler; Nicol, Sam; Diffendorfer, James E.; Thogmartin, Wayne E.; Erickson, Richard A.; Norris, D. Ryan
2017-01-01
Variation in movement across time and space fundamentally shapes the abundance and distribution of populations. Although a variety of approaches model structured population dynamics, they are limited to specific types of spatially structured populations and lack a unifying framework. Here, we propose a unified network-based framework sufficiently novel in its flexibility to capture a wide variety of spatiotemporal processes including metapopulations and a range of migratory patterns. It can accommodate different kinds of age structures, forms of population growth, dispersal, nomadism and migration, and alternative life-history strategies. Our objective was to link three general elements common to all spatially structured populations (space, time and movement) under a single mathematical framework. To do this, we adopt a network modeling approach. The spatial structure of a population is represented by a weighted and directed network. Each node and each edge has a set of attributes which vary through time. The dynamics of our network-based population is modeled with discrete time steps. Using both theoretical and real-world examples, we show how common elements recur across species with disparate movement strategies and how they can be combined under a unified mathematical framework. We illustrate how metapopulations, various migratory patterns, and nomadism can be represented with this modeling approach. We also apply our network-based framework to four organisms spanning a wide range of life histories, movement patterns, and carrying capacities. General computer code to implement our framework is provided, which can be applied to almost any spatially structured population. This framework contributes to our theoretical understanding of population dynamics and has practical management applications, including understanding the impact of perturbations on population size, distribution, and movement patterns. By working within a common framework, there is less chance
Gao, Zilin; Wang, Yinhe; Zhang, Lili
2018-02-01
In the existing research results of the complex dynamical networks controlled, the controllers are mainly used to guarantee the synchronization or stabilization of the nodes’ state, and the terms coupled with connection relationships may affect the behaviors of nodes, this obviously ignores the dynamic common behavior of the connection relationships between the nodes. In fact, from the point of view of large-scale system, a complex dynamical network can be regarded to be composed of two time-varying dynamic subsystems, which can be called the nodes subsystem and the connection relationships subsystem, respectively. Similar to the synchronization or stabilization of the nodes subsystem, some characteristic phenomena can be also emerged in the connection relationships subsystem. For example, the structural balance in the social networks and the synaptic facilitation in the biological neural networks. This paper focuses on the structural balance in dynamic complex networks. Generally speaking, the state of the connection relationships subsystem is difficult to be measured accurately in practical applications, and thus it is not easy to implant the controller directly into the connection relationships subsystem. It is noted that the nodes subsystem and the relationships subsystem are mutually coupled, which implies that the state of the connection relationships subsystem can be affected by the controllable state of nodes subsystem. Inspired by this observation, by using the structural balance theory of triad, the controller with the parameter adaptive law is proposed for the nodes subsystem in this paper, which may ensure the connection relationship matrix to approximate a given structural balance matrix in the sense of the uniformly ultimately bounded (UUB). That is, the structural balance may be obtained by employing the controlling state of the nodes subsystem. Finally, the simulations are used to show the validity of the method in this paper.
Spectroscopic Tools for Quantitative Studies of DNA Structure and Dynamics
DEFF Research Database (Denmark)
Preus, Søren
The main objective of this thesis is to develop quantitative fluorescence-based, spectroscopic tools for probing the 3D structure and dynamics of DNA and RNA. The thesis is founded on six peer-reviewed papers covering mainly the development, characterization and use of fluorescent nucleobase...... analogues. In addition, four software packages is presented for the simulation and quantitative analysis of time-resolved and steady-state UV-Vis absorption and fluorescence experiments....
Yaw control for active damping of structural dynamics
Energy Technology Data Exchange (ETDEWEB)
Ekelund, T. [Chalmers Univ. of Technology, Goeteborg (Sweden). Control Engineering Lab.
1996-12-01
Yaw torque control for reduction of structural dynamic loads in a two-bladed wind turbine is investigated. The models are obtained using rigid-body mechanics. Linear quadratic control theory is utilized for design and analysis. The analysis of two simple examples, where the teeter angle and the tower lateral bending motion are regarded, shows that a time-varying controller has some advantages compared with a time-invariant controller. 6 refs, 9 figs
Sierra Structural Dynamics User's Notes
Energy Technology Data Exchange (ETDEWEB)
Reese, Garth M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2015-10-19
Sierra/SD provides a massively parallel implementation of structural dynamics finite element analysis, required for high fidelity, validated models used in modal, vibration, static and shock analysis of weapons systems. This document provides a users guide to the input for Sierra/SD. Details of input specifications for the different solution types, output options, element types and parameters are included. The appendices contain detailed examples, and instructions for running the software on parallel platforms.
Feedback Linearized Aircraft Control Using Dynamic Cell Structure
Jorgensen, C. C.
1998-01-01
A Dynamic Cell Structure (DCS ) Neural Network was developed which learns a topology representing network (TRN) of F-15 aircraft aerodynamic stability and control derivatives. The network is combined with a feedback linearized tracking controller to produce a robust control architecture capable of handling multiple accident and off-nominal flight scenarios. This paper describes network and its performance for accident scenarios including differential stabilator lock, soft sensor failure, control, stability derivative variation, and turbulence.
Control of Spin Wave Dynamics in Spatially Twisted Magnetic Structures
2017-06-27
control the spin wave dynamics of magnetic structures twisted spatially, we prepared the exchange-coupled films with the hard magnetic L10-FePt and...information writing of magnetic storage and spintronic applications. Introduction and Objective: Recent rapid progress in the research field of nano...scaled bilayer elements is also an important aim of this project. Approach/Method: The exchange-coupled films with the hard magnetic L10-FePt and
Doublet vs. FODO structure: beam dynamics and layout
Eshraqi, M; CERN. Geneva. BE Department
2010-01-01
A FoDo (singlet) structure is designed for the CERN Superconducting Proton LINAC. This architecture is compared to the baseline (doublet) architecture of SPL on the basis of its beam dynamics performance and the required investment. The sensitivity of both layouts to quadrupole gradient errors and misalignment is checked and a correction scheme for beam steering is proposed. Finally a single quad beam dilution scheme is studied and designed for the pilot beam dump.
Dynamic Capital Structure with Callable Debt and Debt Renegotiations
DEFF Research Database (Denmark)
Christensen, Peter Ove; Flor, Christian Riis; Lando, David
2014-01-01
We consider a dynamic trade-off model of a firm’s capital structure with debt renegotiation. Debt holders only accept restructuring offers from equity holders backed by threats which are in the equity holders’ own interest to execute. Our model shows that in a complete information model in which...... taxes and bankruptcy costs are the only frictions, violations of the absolute priority rule (APR) are typically optimal. The size of the bankruptcy costs and the equity holders’ bargaining power affect the size of APR violations, but they have only a minor impact on the choice of capital structure....
Map updates in a dynamic Voronoi data structure
DEFF Research Database (Denmark)
Mioc, Darka; Antón Castro, Francesc/François; Gold, C. M.
2006-01-01
In this paper we are using local and sequential map updates in the Voronoi data structure, which allows us to automatically record each event and performed map updates within the system. These map updates are executed through map construction commands that are composed of atomic actions (geometric...... algorithms for addition, deletion, and motion of spatial objects) on the dynamic Voronoi data structure. The formalization of map commands led to the development of a spatial language comprising a set of atomic operations or constructs on spatial primitives (points and lines), powerful enough to define...
Dynamic soil-structure interaction of monopod and polypod foundations
DEFF Research Database (Denmark)
Andersen, Lars Vabbersgaard
2016-01-01
within the time domain, frequency-independent lumped-parameter models are developed. The paper proposes a decision criterion for determination of which components must be included within a lumped-parameter model in order to account for the structure–soil–structure interaction in an adequate and efficient......The paper concerns the importance of through–soil coupling for structures having foundations with more footings. First, a model for dynamic analysis of polypod footings is established in the frequency domain, employing Green’s function for wave propagation in a layered half-space. To allow analysis...
Dynamic calculation of structures in seismic zones. 2. ed.
International Nuclear Information System (INIS)
Capra, Alain; Davidovici, Victor
1982-01-01
The aims of this book are both didactic and practical. It is therefore addressed to both experienced engineers and students. Some general information about earthquakes and their occurrence is first given. The problem of a simple oscillator is presented. In this way, the reader is provided with an insight into undestanding the dynamic phenomena taking place and is introduced to the concept of response spectra and to an intuitive comprehension of the behavior of structures during earthquakes. The next chapter is devoted to the cases most frequently encountered with multiple oscillator structures. Theoretical studies are based on the usual modal decomposition method. The various practical methods of calculation employed are then examined, emphasis being given to the various different stages involved and to which of them is the best suited for a particular type of structure. Advise is given on how to select the model whose behavior best describes the real structure, both manual and computer methods of calculation being envisaged [fr
Dynamic Changes in Sarcoplasmic Reticulum Structure in Ventricular Myocytes
Directory of Open Access Journals (Sweden)
Amanda L. Vega
2011-01-01
sarcoplasmic reticulum (SR and the sarcolemma where Ca2+ release is activated. Here, we tested the hypothesis that the SR is a structurally inert organelle in ventricular myocytes. Our data suggest that rather than being static, the SR undergoes frequent dynamic structural changes. SR boutons expressing functional ryanodine receptors moved throughout the cell, approaching or moving away from the sarcolemma of ventricular myocytes. These changes in SR structure occurred in the absence of changes in [Ca2+] during EC coupling. Microtubules and the molecular motors dynein and kinesin 1(Kif5b were important regulators of SR motility. These findings support a model in which the SR is a motile organelle capable of molecular motor protein-driven structural changes.
Dynamic testing of nuclear power plant structures: an evaluation
International Nuclear Information System (INIS)
Weaver, H.J.
1980-02-01
Lawrence Livermore Laboratory (LLL) evaluated the applications of system identification techniques to the dynamic testing of nuclear power plant structures and subsystems. These experimental techniques involve exciting a structure and measuring, digitizing, and processing the time-history motions that result. The data can be compared to parameters calculated using finite element or other models of the test systems to validate the model and to verify the seismic analysis. This report summarizes work in three main areas: (1) analytical qualification of a set of computer programs developed at LLL to extract model parameters from the time histories; (2) examination of the feasibility of safely exciting nuclear power plant structures and accurately recording the resulting time-history motions; (3) study of how the model parameters that are extracted from the data be used best to evaluate structural integrity and analyze nuclear power plants
Age structure and cooperation in coevolutionary games on dynamic network
Qin, Zilong; Hu, Zhenhua; Zhou, Xiaoping; Yi, Jingzhang
2015-04-01
Our proposed model imitates the growth of a population and describes the age structure and the level of cooperation in games on dynamic network with continuous changes of structure and topology. The removal of nodes and links caused by age-dependent attack, together with the nodes addition standing for the newborns of population, badly ruins Matthew effect in this coevolutionary process. Though the network is generated by growth and preferential attachment, it degenerates into random network and it is no longer heterogeneous. When the removal of nodes and links is equal to the addition of nodes and links, the size of dynamic network is maintained in steady-state, so is the low level of cooperation. Severe structure variation, homogeneous topology and continuous invasion of new defection jointly make dynamic network unsuitable for the survival of cooperator even when the probability with which the newborn players initially adopt the strategy cooperation is high, while things change slightly when the connections of newborn players are restricted. Fortunately, moderate interactions in a generation trigger an optimal recovering process to encourage cooperation. The model developed in this paper outlines an explanation of the cohesion changes in the development process of an organization. Some suggestions for cooperative behavior improvement are given in the end.
Impact of constrained rewiring on network structure and node dynamics
Rattana, P.; Berthouze, L.; Kiss, I. Z.
2014-11-01
In this paper, we study an adaptive spatial network. We consider a susceptible-infected-susceptible (SIS) epidemic on the network, with a link or contact rewiring process constrained by spatial proximity. In particular, we assume that susceptible nodes break links with infected nodes independently of distance and reconnect at random to susceptible nodes available within a given radius. By systematically manipulating this radius we investigate the impact of rewiring on the structure of the network and characteristics of the epidemic. We adopt a step-by-step approach whereby we first study the impact of rewiring on the network structure in the absence of an epidemic, then with nodes assigned a disease status but without disease dynamics, and finally running network and epidemic dynamics simultaneously. In the case of no labeling and no epidemic dynamics, we provide both analytic and semianalytic formulas for the value of clustering achieved in the network. Our results also show that the rewiring radius and the network's initial structure have a pronounced effect on the endemic equilibrium, with increasingly large rewiring radiuses yielding smaller disease prevalence.
Yang, Bingen
2005-01-01
Stress, Strain, and Structural Dynamics is a comprehensive and definitive reference to statics and dynamics of solids and structures, including mechanics of materials, structural mechanics, elasticity, rigid-body dynamics, vibrations, structural dynamics, and structural controls. This text integrates the development of fundamental theories, formulas and mathematical models with user-friendly interactive computer programs, written in the powerful and popular MATLAB. This unique merger of technical referencing and interactive computing allows instant solution of a variety of engineering problems
Dynamical simulation of structural multiplicity in grain boundaries
International Nuclear Information System (INIS)
Majid, I.; Bristowe, P.D.
1987-06-01
Work on a computer simulation study of a low-energy high-angle boundary structure which is not periodic have been recently reported. This result is of interest since grain boundary structures are usually assumed to have a periodicity corresponding to the appropriate coincidence site lattice (CSL) and many experimental observations of the structure of grain boundaries performed using conventional and high-resolution electron microscopy, electron diffraction and x-ray diffraction appear to support this work. However, this work, using empirical interatomic pair potentials and the relaxation method of molecular statics, have simulated a Σ = 5 36.87 0 (001) twist boundary and found a low energy structure having a larger repeat cell than the CSL and is composed of two different types of structural unit that are randomly distributed in the boundary plane. This result, which has been termed the multiplicity of grain boundary structures, has also been found in the simulation of tilt boundaries. The multiplicity phenomenon is of special interest in twist boundaries since it is used as a structural model to explain the x-ray scattering from a Σ = 5 boundary in gold. These scattering patterns had previously remained unexplained using stable structures that had simple CSL periodicity. Also, the effect of having a multiple number of low energy structural units coexisting in the grain boundary is of more general interest since it implies that the boundary structures may be quasi-periodic and, in some circumstances, may even result in a roughening of the boundary plane. This paper extends this work by showing, using molecular dynamics, that a multiplicity of structural units can actually nucleate spontaneously in a high-angle grain boundary at finite temperatures
DEFF Research Database (Denmark)
Tahavori, Maryamsadat; Shaker, Hamid Reza
A method for model reduction of dynamical systems with the second order structure is proposed in this paper. The proposed technique preserves the second order structure of the system, and also preserves the stability of the original systems. The method uses the controllability and observability...... gramians within the time interval to build the appropriate Petrov-Galerkin projection for dynamical systems within the time interval of interest. The bound on approximation error is also derived. The numerical results are compared with the counterparts from other techniques. The results confirm...
Structural dynamic and resistance to nuclear air blast
International Nuclear Information System (INIS)
Qureshi, S.M.
2003-01-01
A need exists to design protective shelters attached to specialized facilities against nuclear airbursts, explosive shocks and impacting projectiles. Designing such structures against nuclear and missile impact is a challenging task that needs to be looked into for design methodology formulation and practicability. Structures can be designed for overpressure pulsed generated by a nuclear explosion as well as the scabbing and perforation/punching of an impacting projectile. This paper discuses and formulates the methods of dynamic analysis and design required to undertake such a task. Structural resistance to peak overpressure pulse for a 20 KT weapons and smaller tactical nuclear weapons of 1 KT (16 psi, overpressure) size as a direct air blast overpressure has been considered in design of walls, beams and slabs of a special structure under review. The design of shear reinforcement as lacing is also carried out. Adopting the philosophy of strengthening and hardening can minimize the effect of air blast overpressure and projectile impact. The objective is to avoid a major structural failure. The structure then needs to be checked against ballistic penetration by a range of weapons or be required to resist explosive penetration from the charge detonated in contact with the structure. There is also a dire need to formulate protective guidelines for all existing and future critical facilities. (author)
A Novel Double-Piston Magnetorheological Damper for Space Truss Structures Vibration Suppression
Directory of Open Access Journals (Sweden)
Qiang Wang
2014-01-01
Full Text Available The design, fabrication, and testing of a new double-piston MR damper for space applications are discussed. The design concept for the damper is described in detail. The electromagnetic analysis of the design and the fabrication of the MR damper are also presented. The design analysis shows that the damper meets the weight and size requirements for being included in a space truss structure. The prototype design is tested in a damper dynamometer. The test results show that the damper can provide nearly 80 N of damping force at its maximum velocity and current. The test results also show that the seal drag could contribute significantly to the damping forces. Additionally, the test results indicate that both the work by the damper and damping force increase rapidly with increasing current at lower currents and taper off at higher currents as the damper starts to saturate. The damper force versus velocity plots show hysteresis in both pre- and postyield regions and asymmetric forces in jounce and rebound. A model is proposed for representing the force-displacement, force-velocity, and asymmetric forces observed in test results. A comparison of the modeling results and test data indicates that the model accurately represents the force characteristics of the damper.
Directory of Open Access Journals (Sweden)
Ratna Juwita
2013-04-01
Full Text Available Cell membranes are composed mainly of phospholipids which are in turn, composed of five major chemical elements: carbon, hydrogen, nitrogen, oxygen, and phosphorus. Recent studies have suggested the possibility of sustaining life if the phosphorus is substituted by arsenic. Although this issue is still controversial, it is of interest to investigate the properties of arsenated-lipid bilayers to evaluate this possibility. In this study, we simulated arsenated-lipid, 1-palmitoyl-2-oleoyl-sn-glycero-3-arsenocholine (POAC, lipid bilayers using all-atom molecular dynamics to understand basic structural and dynamical properties, in particular, the differences from analogous 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, (POPC lipid bilayers. Our simulations showed that POAC lipid bilayers have distinct structural and dynamical properties from those of native POPC lipid bilayers. Relative to POPC lipid bilayers, POAC lipid bilayers have a more compact structure with smaller lateral areas and greater order. The compact structure of POAC lipid bilayers is due to the fact that more inter-lipid salt bridges are formed with arsenate-choline compared to the phosphate-choline of POPC lipid bilayers. These inter-lipid salt bridges bind POAC lipids together and also slow down the head group rotation and lateral diffusion of POAC lipids. Thus, it would be anticipated that POAC and POPC lipid bilayers would have different biological implications.
Carr, J. K.; Buchanan, L. E.; Schmidt, J. R.; Zanni, M. T.; Skinner, J. L.
2013-01-01
Urea/water is an archetypical “biological” mixture, and is especially well known for its relevance to protein thermodynamics, as urea acts as a protein denaturant at high concentration. This behavior has given rise to an extended debate concerning urea’s influence on water structure. Based on a variety of methods and of definitions of water structure, urea has been variously described as a structure-breaker, a structure-maker, or as remarkably neutral towards water. Because of its sensitivity to microscopic structure and dynamics, vibrational spectroscopy can help resolve these debates. We report experimental and theoretical spectroscopic results for the OD stretch of HOD/H2O/urea mixtures (linear IR, 2DIR, and pump-probe anisotropy decay) and for the CO stretch of urea-D4/D2O mixtures (linear IR only). Theoretical results are obtained using existing approaches for water, and a modification of a frequency map developed for acetamide. All absorption spectra are remarkably insensitive to urea concentration, consistent with the idea that urea only very weakly perturbs water structure. Both this work and experiments by Rezus and Bakker, however, show that water’s rotational dynamics are slowed down by urea. Analysis of the simulations casts doubt on the suggestion that urea immobilizes particular doubly hydrogen bonded water molecules. PMID:23841646
International Nuclear Information System (INIS)
Cen, Ling; Hutzen, Brian; Ball, Sarah; DeAngelis, Stephanie; Chen, Chun-Liang; Fuchs, James R; Li, Chenglong; Li, Pui-Kai; Lin, Jiayuh
2009-01-01
Colorectal carcinoma is one of the major causes of morbidity and mortality in the Western World. Novel therapeutic approaches are needed for colorectal carcinoma. Curcumin, the active component and yellow pigment of turmeric, has been reported to have several anti-cancer activities including anti-proliferation, anti-invasion, and anti-angiogenesis. Clinical trials have suggested that curcumin may serve as a potential preventive or therapeutic agent for colorectal cancer. We compared the inhibitory effects of curcumin and novel structural analogues, GO-Y030, FLLL-11, and FLLL-12, in three independent human colorectal cancer cell lines, SW480, HT-29, and HCT116. MTT cell viability assay was used to examine the cell viability/proliferation and western blots were used to determine the level of PARP cleavages. Half-Maximal inhibitory concentrations (IC 50 ) were calculated using Sigma Plot 9.0 software. Curcumin inhibited cell viability in all three of the human colorectal cancer cell lines studied with IC 50 values ranging between 10.26 μM and 13.31 μM. GO-Y030, FLLL-11, and FLLL-12 were more potent than curcumin in the inhibition of cell viability in these three human colorectal cancer cell lines with IC 50 values ranging between 0.51 μM and 4.48 μM. In addition, FLLL-11 and FLLL-12 exhibit low toxicity to WI-38 normal human lung fibroblasts with an IC-50 value greater than 1,000 μM. GO-Y030, FLLL-11, and FLLL-12 are also more potent than curcumin in the induction of apoptosis, as evidenced by cleaved PARP and cleaved caspase-3 in all three human colorectal cancer cell lines studied. The results indicate that the three curcumin analogues studied exhibit more potent inhibitory activity than curcumin in human colorectal cancer cells. Thus, they may have translational potential as chemopreventive or therapeutic agents for colorectal carcinoma
International Nuclear Information System (INIS)
Zanotti, J.M.
1997-01-01
This memoir includes five chapters. In the first chapter, are given the elements of the neutrons scattering theory that is used in this study. the second chapter is devoted to a general presentation of the interaction between biological macro molecule and water. The third part is dedicated to the study of the structure and the dynamics of interfacial water in the neighbouring of model systems, the vycor and the amorphous carbon. The results presented in this part are compared with these one relative to water dynamics at the C-phycocyanin surface. This study makes the object of the fourth chapter. Then, in the fifth and last chapter are discussed the results relative to the role of hydratation on the parv-albumin dynamics for which have been combined the neutron quasi elastic incoherent scattering and the nuclear magnetic resonance of the carbon 13 solid in natural abundance
Testing the Lag Structure of Assets’ Realized Volatility Dynamics
Directory of Open Access Journals (Sweden)
Francesco Audrino
2017-12-01
Full Text Available A (conservative test is applied to investigate the optimal lag structure for modelingrealized volatility dynamics. The testing procedure relies on the recent theoretical results that showthe ability of the adaptive least absolute shrinkage and selection operator (adaptive lasso to combinee cient parameter estimation, variable selection, and valid inference for time series processes. In anapplication to several constituents of the S&P 500 index it is shown that (i the optimal significantlag structure is time-varying and subject to drastic regime shifts that seem to happen across assetssimultaneously; (ii in many cases the relevant information for prediction is included in the first 22lags, corroborating previous results concerning the accuracy and the diffculty of outperforming outof-sample the heterogeneous autoregressive (HAR model; and (iii some common features of theoptimal lag structure can be identified across assets belonging to the same market segment or showinga similar beta with respect to the market index.
Optical Fibres Contactless Sensor for Dynamic Testing of Lightweight Structures
Directory of Open Access Journals (Sweden)
L. Bregant
2008-01-01
Full Text Available With dynamic testing, engineers describe activities focused on the identification of some properties of vibrating structures. This step requires for the measurements of excitations and responses signals, applying appropriate sensors directly on the test article. These instruments modify the system's mass and stiffness distributions and eventually the eigen-properties of the structure. These errors become unacceptable especially when testing lightweight structures. This paper shows the results of some tests performed on a small compressor with the purpose of identifying the blades’ natural frequencies and modes. It compares the acquisitions performed with standard accelerometers and two different contact-less systems using as exciters either a micro-hammer or a micro inertial shaker. The paper shows how the contact-less sensors provide good quality data and consistent results in the mode identification phase.
Fouling Kinetics and Associated Dynamics of Structural Modifications
DEFF Research Database (Denmark)
Jacob, Jerome; Prádanos, Pedro; Calvo, J. I.
1998-01-01
It is shown that the fouling behaviour of microfiltration membranes does not agree within all the time ranges of any of the commonly used membrane blocking models (i.e. complete, standard, intermediate or cake blocking). The resulting experimental kinetics of flux decline do not fit to only one...... of these models, but according to a successive or simultaneous coexistence of two or more of them. This is studied by analysing the structural modifications associated with the fouling kinetics. To achieve this goal, here we analyse the dynamical changes on the structure of four microporous membranes made...... by Sartorius (ST02 and ST045, neutral) and Spectrum (SP02 and SP045, positively charged) when fouled by permeating a protein aqueous solution (bovine serum albumin (BSA) at 1 g l(-1)) under 10 kPa in a dead-end device. The structure after different fouling times is obtained by using an extended bubble point...
Mapping the structural and dynamical features of kinesin motor domains.
Directory of Open Access Journals (Sweden)
Guido Scarabelli
Full Text Available Kinesin motor proteins drive intracellular transport by coupling ATP hydrolysis to conformational changes that mediate directed movement along microtubules. Characterizing these distinct conformations and their interconversion mechanism is essential to determining an atomic-level model of kinesin action. Here we report a comprehensive principal component analysis of 114 experimental structures along with the results of conventional and accelerated molecular dynamics simulations that together map the structural dynamics of the kinesin motor domain. All experimental structures were found to reside in one of three distinct conformational clusters (ATP-like, ADP-like and Eg5 inhibitor-bound. These groups differ in the orientation of key functional elements, most notably the microtubule binding α4-α5, loop8 subdomain and α2b-β4-β6-β7 motor domain tip. Group membership was found not to correlate with the nature of the bound nucleotide in a given structure. However, groupings were coincident with distinct neck-linker orientations. Accelerated molecular dynamics simulations of ATP, ADP and nucleotide free Eg5 indicate that all three nucleotide states could sample the major crystallographically observed conformations. Differences in the dynamic coupling of distal sites were also evident. In multiple ATP bound simulations, the neck-linker, loop8 and the α4-α5 subdomain display correlated motions that are absent in ADP bound simulations. Further dissection of these couplings provides evidence for a network of dynamic communication between the active site, microtubule-binding interface and neck-linker via loop7 and loop13. Additional simulations indicate that the mutations G325A and G326A in loop13 reduce the flexibility of these regions and disrupt their couplings. Our combined results indicate that the reported ATP and ADP-like conformations of kinesin are intrinsically accessible regardless of nucleotide state and support a model where neck
Dynamico-FE: A Structure-Preserving Hydrostatic Dynamical Core
Eldred, Christopher; Dubos, Thomas; Kritsikis, Evaggelos
2017-04-01
It is well known that the inviscid, adiabatic equations of atmospheric motion constitute a non-canonical Hamiltonian system, and therefore posses many important conserved quantities such as as mass, potential vorticity and total energy. In addition, there are also key mimetic properties (such as curl grad = 0) of the underlying continuous vector calculus. Ideally, a dynamical core should have similar properties. A general approach to deriving such structure-preserving numerical schemes has been developed under the frameworks of Hamiltonian methods and mimetic discretizations, and over the past decade, there has been a great deal of work on the development of atmospheric dynamical cores using these techniques. An important example is Dynamico, which conserves mass, potential vorticity and total energy; and possesses additional mimetic properties such as a curl-free pressure gradient. Unfortunately, the underlying finite-difference discretization scheme used in Dynamico has been shown to be inconsistent on general grids. To resolve these accuracy issues, a scheme based on mimetic Galerkin discretizations has been developed that achieves higher-order accuracy while retaining the structure-preserving properties of the existing discretization. This presentation will discuss the new dynamical core, termed Dynamico-FE, and show results from a standard set of test cases on both the plane and the sphere.
Polyacrylic acids–bovine serum albumin complexation: Structure and dynamics
International Nuclear Information System (INIS)
Othman, Mohamed; Aschi, Adel; Gharbi, Abdelhafidh
2016-01-01
The study of the mixture of BSA with polyacrylic acids at different masses versus pH allowed highlighting the existence of two regimes of weak and strong complexation. These complexes were studied in diluted regime concentration, by turbidimetry, dynamic light scattering (DLS), zeta-potential measurements and nuclear magnetic resonance (NMR). We have followed the pH effect on the structure and properties of the complex. This allowed refining the interpretation of the phase diagram and understanding the observed phenomena. The NMR measurements allowed probing the dynamics of the constituents versus the pH. The computational method was used to precisely determine the electrostatic potential of BSA and how the polyelectrolyte binds to it at different pH. - Highlights: • Influence of physico-chemical parameters on the electrostatic interactions in the complex system (polyelectrolyte/protein). • Stabilization and encapsulation of biological macromolecules solution by mean of polyelectrolyte. • Properties and structure of mixture obtained by screening the charges of globular protein and at different masses of polyacrylic acids. • Dynamic of the constituents formed by complexes particles. • Evaluation of the electrostatic properties of bovine serum albumin versus pH through solution of the Poisson-Boltzmann equation.
Dynamical soil-structure interactions: influence of soil behaviour nonlinearities
International Nuclear Information System (INIS)
Gandomzadeh, Ali
2011-01-01
The interaction of the soil with the structure has been largely explored the assumption of material and geometrical linearity of the soil. Nevertheless, for moderate or strong seismic events, the maximum shear strain can easily reach the elastic limit of the soil behavior. Considering soil-structure interaction, the nonlinear effects may change the soil stiffness at the base of the structure and therefore energy dissipation into the soil. Consequently, ignoring the nonlinear characteristics of the dynamic soil-structure interaction (DSSI) this phenomenon could lead to erroneous predictions of structural response. The goal of this work is to implement a fully nonlinear constitutive model for soils into a numerical code in order to investigate the effect of soil nonlinearity on dynamic soil structure interaction. Moreover, different issues are taken into account such as the effect of confining stress on the shear modulus of the soil, initial static condition, contact elements in the soil-structure interface, etc. During this work, a simple absorbing layer method based on a Rayleigh/Caughey damping formulation, which is often already available in existing Finite Element softwares, is also presented. The stability conditions of the wave propagation problems are studied and it is shown that the linear and nonlinear behavior are very different when dealing with numerical dispersion. It is shown that the 10 points per wavelength rule, recommended in the literature for the elastic media is not sufficient for the nonlinear case. The implemented model is first numerically verified by comparing the results with other known numerical codes. Afterward, a parametric study is carried out for different types of structures and various soil profiles to characterize nonlinear effects. Different features of the DSSI are compared to the linear case: modification of the amplitude and frequency content of the waves propagated into the soil, fundamental frequency, energy dissipation in
Directory of Open Access Journals (Sweden)
M. Javanpour
2017-02-01
Full Text Available Prediction of existing buildings’ vulnerability by future earthquakes is one of the most essential topics in structural engineering. Modeling steel structures is a giant step in determining the damage caused by the earthquake, as such structures are increasingly being used in constructions. Hence, two same-order steel structures with two types of structural systems were selected (coaxial moment frames and moment frame. In most cases, a specific structure needs to satisfy several functional levels. For this purpose, a method is required to determine the input request to the structures under possible earthquakes. Therefore, the Incremental Dynamic Analysis (IDA was preferred to the Push-Over non-linear static method for the analysis and design of the considered steel structures, due its accuracy and effect of higher modes at the same time intervals. OpenSees software was used to perform accurate nonlinear analysis of the steel structure. Two parameters (spectral acceleration and maximum ground acceleration were introduced to the modeled frames to compare the numerical correlations of seismic vulnerability obtained by two statistical methods based on the "log-normal distribution" and "logistics distribution", and finally, the parameters of displacement and drift were assessed after analysis.
Turbulent structure and dynamics of swirled, strongly pulsed jet diffusion flames
Liao, Ying-Hao; Hermanson, James C.
2013-01-01
The structure and dynamics of swirled, strongly pulsed, turbulent jet diffusion flames were examined experimentally in a co-flow swirl combustor. The dynamics of the large-scale flame structures, including variations in flame dimensions, the degree
2018-01-01
The structural heterogeneity of water at various interfaces can be revealed by time-resolved sum-frequency generation spectroscopy. The vibrational dynamics of the O–H stretch vibration of interfacial water can reflect structural variations. Specifically, the vibrational lifetime is typically found to increase with increasing frequency of the O–H stretch vibration, which can report on the hydrogen-bonding heterogeneity of water. We compare and contrast vibrational dynamics of water in contact with various surfaces, including vapor, biomolecules, and solid interfaces. The results reveal that variations in the vibrational lifetime with vibrational frequency are very typical, and can frequently be accounted for by the bulk-like heterogeneous response of interfacial water. Specific interfaces exist, however, for which the behavior is less straightforward. These insights into the heterogeneity of interfacial water thus obtained contribute to a better understanding of complex phenomena taking place at aqueous interfaces, such as photocatalytic reactions and protein folding. PMID:29490138
Energy Technology Data Exchange (ETDEWEB)
Kennedy, A.R.; Symons, M.C.
1987-05-01
We report here that dimethylsulfoxide (DMSO): suppresses radiation-induced transformation in vitro, even when DMSO treatments begin as late as 10 days post-irradiation (when cells are in the confluent, stationary phase of growth); inhibits the 12-O-tetradecanoylphorbol-13-acetate (TPA) enhancement of radiation-induced transformation in vitro; does not affect the expression of transformed cells as foci (when surrounded by non-transformed cells); and may be affecting radiation-induced transformation through its solvent properties (i.e. the Water Structure theory), while its effects on the TPA enhancement of radiation transformation may be mediated by its free radical scavenging abilities. DMSO, dimethylformamide (DMF) and dimethylacetamide (DMA) are similar solvents which are all very effective in their ability to suppress radiation-induced transformation in vitro (at concentrations in the cellular media down to 0.01%). As DMSO is known to be an extremely effective OH. free-radical scavenging agent, while DMF and DMA are not as efficient at scavenging free radicals, our results suggest that properties other than free-radical scavenging ability may be important in the suppressive effects of these compounds on radiation-induced transformation in vitro. It is known that low concentrations of such basic aprotic solvents modify water structure so as to suppress the protic (H-bond donor) reactivity of water and enhance its basic (H-bond receptor) reactivity. These reactivity changes may well be responsible for the effects noted above. DMSO, DMF and DMA are also capable of suppressing the TPA enhancement of radiation transformation (at concentrations of the compounds of 0.1% or higher). For this effect, the ability of these compounds to scavenge OH. shows a general correlation with their ability to suppress the TPA enhancement of transformation, suggesting that the Radical Scavenger theory may explain the ability of DMSO to suppress promotion in vitro.
Dynamical spin structure factors of α-RuCl3
Suzuki, Takafumi; Suga, Sei-ichiro
2018-03-01
Honeycomb-lattice magnet α-RuCl3 is considered to be a potential candidate of realizing Kitaev spin liquid, although this material undergoes a phase transition to the zigzag magnetically ordered state at T N ∼ 7 K. Quite recently, inelastic neutron-scattering experiments using single crystal α-RuCl3 have unveiled characteristic dynamical properties. We calculate dynamical spin structure factors of three ab-initio models for α-RuCl3 with an exact numerical diagonalization method. We also calculate temperature dependences of the specific heat by employing thermal pure quantum states. We compare our numerical results with the experiments and discuss characteristics obtained by using three ab-initio models.
Stage-Structured Population Dynamics of AEDES AEGYPTI
Yusoff, Nuraini; Budin, Harun; Ismail, Salemah
Aedes aegypti is the main vector in the transmission of dengue fever, a vector-borne disease affecting world population living in tropical and sub-tropical countries. Better understanding of the dynamics of its population growth will help in the efforts of controlling the spread of this disease. In looking at the population dynamics of Aedes aegypti, this paper explored the stage-structured modeling of the population growth of the mosquito using the matrix population model. The life cycle of the mosquito was divided into five stages: eggs, larvae, pupae, adult1 and adult2. Developmental rates were obtained for the average Malaysian temperature and these were used in constructing the transition matrix for the matrix model. The model, which was based only on temperature, projected that the population of Aedes aegypti will blow up with time, which is not realistic. For further work, other factors need to be taken into account to obtain a more realistic result.
Structural Influence on Excited State Dynamics in Simple Amines
DEFF Research Database (Denmark)
Klein, Liv Bærenholdt
experiments with calculations, provides new insight into the nature of the internal conversion processes that mediate the dynamical evolution between Rydberg states, and how structural variations in simple amine system have a large impact on the non-adiabatic processes. The experimental method of choice...... is femtosecond time-resolved photoelectron velocity map imaging (VMI), which is a newtechnique in the Copenhagen lab. The design, building and implementation of the VMI spectrometer has been a very substantial part of the thesis work. This techniques oers enhanced information content in the form of ecient...... and sensitive collection of photoelectron spectra. In particular, the angleresolved data available from the VMI approach provides highly detailed mechanistic insight about the relaxation pathways. One striking novel nding is that for tertiary amines, the critical factor driving the non-adiabatic dynamics...
Neutrons probing the structure and dynamics of liquids
International Nuclear Information System (INIS)
Leclercq-Hugeux, F.; Coulet, M.V.; Gaspard, J.P.; Pouget, St.; Zanotti, J.M.
2007-01-01
This article illustrates the benefits of neutron techniques to the understanding of the liquid state. As opposed to the nearly complete order of crystals or the nearly complete disorder of gas, the disorder of a liquid is partial and results from dynamical events acting on a broad range of space and time scales. Consequently, no single, simple parameter can encompass the concept of order or disorder in the liquid state. The wide variety of neutron techniques (diffraction, quasi-elastic and inelastic scattering) is a key asset to solve the issue. Selected studies ranging over typical interactions and conditions relevant to liquids (metallic, covalent, molecular, liquids near a phase transition and confined fluids) are presented. In each case, both structural and dynamical aspects, along with the connections to complementary techniques (computer simulation, X-ray absorption and/or scattering) are highlighted. (authors)
Poisson structure of dynamical systems with three degrees of freedom
Gümral, Hasan; Nutku, Yavuz
1993-12-01
It is shown that the Poisson structure of dynamical systems with three degrees of freedom can be defined in terms of an integrable one-form in three dimensions. Advantage is taken of this fact and the theory of foliations is used in discussing the geometrical structure underlying complete and partial integrability. Techniques for finding Poisson structures are presented and applied to various examples such as the Halphen system which has been studied as the two-monopole problem by Atiyah and Hitchin. It is shown that the Halphen system can be formulated in terms of a flat SL(2,R)-valued connection and belongs to a nontrivial Godbillon-Vey class. On the other hand, for the Euler top and a special case of three-species Lotka-Volterra equations which are contained in the Halphen system as limiting cases, this structure degenerates into the form of globally integrable bi-Hamiltonian structures. The globally integrable bi-Hamiltonian case is a linear and the SL(2,R) structure is a quadratic unfolding of an integrable one-form in 3+1 dimensions. It is shown that the existence of a vector field compatible with the flow is a powerful tool in the investigation of Poisson structure and some new techniques for incorporating arbitrary constants into the Poisson one-form are presented herein. This leads to some extensions, analogous to q extensions, of Poisson structure. The Kermack-McKendrick model and some of its generalizations describing the spread of epidemics, as well as the integrable cases of the Lorenz, Lotka-Volterra, May-Leonard, and Maxwell-Bloch systems admit globally integrable bi-Hamiltonian structure.
Dynamical suppression of nuclear-spin decoherence time in Si and GaAs using inversion pulses
International Nuclear Information System (INIS)
Watanabe, S.; Harada, J.; Sasaki, S.; Hirayama, Y.
2007-01-01
We found that nuclear-spin decoherence is suppressed by applying inversion pulses such as alternating phase Carr-Purcell (APCP) and Carr-Purcell-Meiboom-Gill (CPMG) sequences in silicon and GaAs. The decoherence time reaches ∼1.3s by applying inversion pulses, which is ∼200 times as long as the characteristic decay time obtained from the Hahn echo sequence (∼6ms) in silicon
A broadband frequency-tunable dynamic absorber for the vibration control of structures
International Nuclear Information System (INIS)
Komatsuzaki, T; Inoue, T; Terashima, O
2016-01-01
A passive-type dynamic vibration absorber (DVA) is basically a mass-spring system that suppresses the vibration of a structure at a particular frequency. Since the natural frequency of the DVA is usually tuned to a frequency of particular excitation, the DVA is especially effective when the excitation frequency is close to the natural frequency of the structure. Fixing the physical properties of the DVA limits the application to a narrowband, harmonically excited vibration problem. A frequency-tunable DVA that can modulate its stiffness provides adaptability to the vibration control device against non-stationary disturbances. In this paper, we suggest a broadband frequency-tunable DVA whose natural frequency can be extended by 300% to the nominal value using the magnetorheological elastomers (MREs). The frequency adjustability of the proposed absorber is first shown. The real-time vibration control performance of the frequency-tunable absorber for an acoustically excited plate having multiple resonant peaks is then evaluated. Investigations show that the vibration of the structure can be effectively reduced with an improved performance by the DVA in comparison to the conventional passive- type absorber. (paper)
Electronic structure and molecular dynamics of Na2Li
Malcolm, Nathaniel O. J.; McDouall, Joseph J. W.
Following the first report (Mile, B., Sillman, P. D., Yacob, A. R. and Howard, J. A., 1996, J. chem. Soc. Dalton Trans , 653) of the EPR spectrum of the mixed alkali-metal trimer Na2Li a detailed study has been made of the electronic structure and structural dynamics of this species. Two isomeric forms have been found: one of the type, Na-Li-Na, of C , symmetry and another, Li-Na-Na, of C symmetry. Also, there are two linear saddle points which correspond to 'inversion' transition structures, and a saddle point of C symmetry which connects the two minima. A molecular dynamics investigation of these species shows that, at the temperature of the reported experiments (170 K), the C minimum is not 'static', but undergoes quite rapid inversion. At higher temperatures the C minimum converts to the C form, but by a mechanism very different from that suggested by minimum energy path considerations. 2 2v s s 2v 2v s
The Response of Simple Polymer Structures Under Dynamic Loading
Proud, William; Ellison, Kay; Yapp, Su; Cole, Cloe; Galimberti, Stefano; Institute of Shock Physics Team
2017-06-01
The dynamic response of polymeric materials has been widely studied with the effects of degree of crystallinity, strain rate, temperature and sample size being commonly reported. This study uses a simple PMMA structure, a right cylindrical sample, with structural features such as holes. The features are added an varied in a systematic fashion. Samples were dynamically loaded using a Split Hopkinson Pressure Bar up to failure. The resulting stress-strain curves are presented showing the change in sample response. The strain to failure is shown to increase initially with the presence of holes, while failure stress is relatively unaffected. The fracture patterns seen in the failed samples change, with tensile cracks, Hertzian cones, shear effects being dominant for different holes sizes and geometries. The sample were prepared by laser cutting and checked for residual stress before experiment. The data is used to validate predictive model predictions where material, structure and damage are included.. The Institute of Shock Physics acknowledges the support of Imperial College London and the Atomic Weapons Establishment.
A Comparative Study on Optimal Structural Dynamics Using Wavelet Functions
Directory of Open Access Journals (Sweden)
Seyed Hossein Mahdavi
2015-01-01
Full Text Available Wavelet solution techniques have become the focus of interest among researchers in different disciplines of science and technology. In this paper, implementation of two different wavelet basis functions has been comparatively considered for dynamic analysis of structures. For this aim, computational technique is developed by using free scale of simple Haar wavelet, initially. Later, complex and continuous Chebyshev wavelet basis functions are presented to improve the time history analysis of structures. Free-scaled Chebyshev coefficient matrix and operation of integration are derived to directly approximate displacements of the corresponding system. In addition, stability of responses has been investigated for the proposed algorithm of discrete Haar wavelet compared against continuous Chebyshev wavelet. To demonstrate the validity of the wavelet-based algorithms, aforesaid schemes have been extended to the linear and nonlinear structural dynamics. The effectiveness of free-scaled Chebyshev wavelet has been compared with simple Haar wavelet and two common integration methods. It is deduced that either indirect method proposed for discrete Haar wavelet or direct approach for continuous Chebyshev wavelet is unconditionally stable. Finally, it is concluded that numerical solution is highly benefited by the least computation time involved and high accuracy of response, particularly using low scale of complex Chebyshev wavelet.
Evolutionary game dynamics in a growing structured population
Energy Technology Data Exchange (ETDEWEB)
Poncela, Julia; Gomez-Gardenes, Jesus; Moreno, Yamir [Institute for Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza, E-50009 Zaragoza (Spain); Traulsen, Arne [Emmy-Noether Group for Evolutionary Dynamics, Department of Evolutionary Ecology, Max Planck Institute for Evolutionary Biology, August-Thienemann-Strasse 2, 24306 Ploen (Germany)], E-mail: traulsen@evolbio.mpg.de
2009-08-15
We discuss a model for evolutionary game dynamics in a growing, network-structured population. In our model, new players can either make connections to random preexisting players or preferentially attach to those that have been successful in the past. The latter depends on the dynamics of strategies in the game, which we implement following the so-called Fermi rule such that the limits of weak and strong strategy selection can be explored. Our framework allows to address general evolutionary games. With only two parameters describing the preferential attachment and the intensity of selection, we describe a wide range of network structures and evolutionary scenarios. Our results show that even for moderate payoff preferential attachment, over represented hubs arise. Interestingly, we find that while the networks are growing, high levels of cooperation are attained, but the same network structure does not promote cooperation as a static network. Therefore, the mechanism of payoff preferential attachment is different to those usually invoked to explain the promotion of cooperation in static, already-grown networks.
Evolutionary game dynamics in a growing structured population
International Nuclear Information System (INIS)
Poncela, Julia; Gomez-Gardenes, Jesus; Moreno, Yamir; Traulsen, Arne
2009-01-01
We discuss a model for evolutionary game dynamics in a growing, network-structured population. In our model, new players can either make connections to random preexisting players or preferentially attach to those that have been successful in the past. The latter depends on the dynamics of strategies in the game, which we implement following the so-called Fermi rule such that the limits of weak and strong strategy selection can be explored. Our framework allows to address general evolutionary games. With only two parameters describing the preferential attachment and the intensity of selection, we describe a wide range of network structures and evolutionary scenarios. Our results show that even for moderate payoff preferential attachment, over represented hubs arise. Interestingly, we find that while the networks are growing, high levels of cooperation are attained, but the same network structure does not promote cooperation as a static network. Therefore, the mechanism of payoff preferential attachment is different to those usually invoked to explain the promotion of cooperation in static, already-grown networks.
Efficient placement of structural dynamics sensors on the space station
Lepanto, Janet A.; Shepard, G. Dudley
1987-01-01
System identification of the space station dynamic model will require flight data from a finite number of judiciously placed sensors on it. The placement of structural dynamics sensors on the space station is a particularly challenging problem because the station will not be deployed in a single mission. Given that the build-up sequence and the final configuration for the space station are currently undetermined, a procedure for sensor placement was developed using the assembly flights 1 to 7 of the rephased dual keel space station as an example. The procedure presented approaches the problem of placing the sensors from an engineering, as opposed to a mathematical, point of view. In addition to locating a finite number of sensors, the procedure addresses the issues of unobserved structural modes, dominant structural modes, and the trade-offs involved in sensor placement for space station. This procedure for sensor placement will be applied to revised, and potentially more detailed, finite element models of the space station configuration and assembly sequence.
Modeling structured population dynamics using data from unmarked individuals
Grant, Evan H. Campbell; Zipkin, Elise; Thorson, James T.; See, Kevin; Lynch, Heather J.; Kanno, Yoichiro; Chandler, Richard; Letcher, Benjamin H.; Royle, J. Andrew
2014-01-01
The study of population dynamics requires unbiased, precise estimates of abundance and vital rates that account for the demographic structure inherent in all wildlife and plant populations. Traditionally, these estimates have only been available through approaches that rely on intensive mark–recapture data. We extended recently developed N-mixture models to demonstrate how demographic parameters and abundance can be estimated for structured populations using only stage-structured count data. Our modeling framework can be used to make reliable inferences on abundance as well as recruitment, immigration, stage-specific survival, and detection rates during sampling. We present a range of simulations to illustrate the data requirements, including the number of years and locations necessary for accurate and precise parameter estimates. We apply our modeling framework to a population of northern dusky salamanders (Desmognathus fuscus) in the mid-Atlantic region (USA) and find that the population is unexpectedly declining. Our approach represents a valuable advance in the estimation of population dynamics using multistate data from unmarked individuals and should additionally be useful in the development of integrated models that combine data from intensive (e.g., mark–recapture) and extensive (e.g., counts) data sources.
Improving the Dynamic Characteristics of Body-in-White Structure Using Structural Optimization
Directory of Open Access Journals (Sweden)
Aizzat S. Yahaya Rashid
2014-01-01
Full Text Available The dynamic behavior of a body-in-white (BIW structure has significant influence on the noise, vibration, and harshness (NVH and crashworthiness of a car. Therefore, by improving the dynamic characteristics of BIW, problems and failures associated with resonance and fatigue can be prevented. The design objectives attempt to improve the existing torsion and bending modes by using structural optimization subjected to dynamic load without compromising other factors such as mass and stiffness of the structure. The natural frequency of the design was modified by identifying and reinforcing the structure at critical locations. These crucial points are first identified by topology optimization using mass and natural frequencies as the design variables. The individual components obtained from the analysis go through a size optimization step to find their target thickness of the structure. The thickness of affected regions of the components will be modified according to the analysis. The results of both optimization steps suggest several design modifications to achieve the target vibration specifications without compromising the stiffness of the structure. A method of combining both optimization approaches is proposed to improve the design modification process.
Structure and Dynamics of Polymer/Polymer grafted nanoparticle composite
Archer, Lynden
Addition of nanoparticles to polymers is a well-practiced methodology for augmenting various properties of the polymer host, including mechanical strength, thermal stability, barrier properties, dimensional stability and wear resistance. Many of these property changes are known to arise from nanoparticle-induced modification of polymer structure and chain dynamics, which are strong functions of the dispersion state of the nanoparticles' and on their relative size (D) to polymer chain dimensions (e.g. Random coil radius Rg or entanglement mesh size a) . This talk will discuss polymer nanocomposites (PNCs) comprised of Polyethylene Glycol (PEG) tethered silica nanoparticles (SiO2-PEG) dispersed in polymers as model systems for investigating phase stability and dynamics of PNCs. On the basis of small-angle X-ray Scattering, it will be shown that favorable enthalpic interactions between particle-tethered chains and a polymer host provides an important mechanism for creating PNCs in which particle aggregation is avoided. The talk will report on polymer and particle scale dynamics in these materials and will show that grafted nanoparticles well dispersed in a polymer host strongly influence the host polymer relaxation dynamics on all timescales and the polymers in turn produce dramatic changes in the nature (from diffusive to hyperdiffusive) and speed of nano particle decorrelation dynamics at the polymer entanglement threshold. A local viscosity model capable of explaining these observations is discussed and the results compared with scaling theories for NP motions in polymers This material is based on work supported by the National Science Foundation Award Nos. DMR-1609125 and CBET-1512297.
International Nuclear Information System (INIS)
Kelton, K F
2017-01-01
The liquid phase remains poorly understood. In many cases, the densities of liquids and their crystallized solid phases are similar, but since they are amorphous they lack the spatial order of the solid. Their dynamical properties change remarkably over a very small temperature range. At high temperatures, near their melting temperature, liquids flow easily under shear. However, only a few hundred degrees lower flow effectively ceases, as the liquid transforms into a solid-like glass. This temperature-dependent dynamical behavior is frequently characterized by the concept of kinetic fragility (or, generally, simply fragility). Fragility is believed to be an important quantity in glass formation, making it of significant practical interest. The microscopic origin of fragility remains unclear, however, making it also of fundamental interest. It is widely (although not uniformly) believed that the dynamical behavior is linked to the atomic structure of the liquid, yet experimental studies show that although the viscosity changes by orders of magnitude with temperature, the structural change is barely perceptible. In this article the concept of fragility is discussed, building to a discussion of recent results in metallic glass-forming liquids that demonstrate the presumed connection between structural and dynamical changes. In particular, it becomes possible to define a structural fragility parameter that can be linked with the kinetic fragility. (topical review)
Performance of dynamic safety barriers-Structuring, modelling and visualization
Wikdahl, Olga
2014-01-01
The main objective of this master thesis is to discuss performance of dynamic safety barriers. A comprehensive literature review is performed in order to get understanding what dynamic safety barrier is. Three different concepts of dynamic safety barriers based on various meanings of dynamic were derived from the literature review: - dynamic safety barriers related to motion or physical force - dynamic safety barriers as updated barriers from dynamic risk analysis - dynamic safety ...
Phase Structure and Dynamics of QCD–A Functional Perspective
International Nuclear Information System (INIS)
Strodthoff, Nils
2017-01-01
The understanding of the phase structure and the fundamental properties of QCD matter from its microscopic description requires appropriate first-principle approaches. Here I review the progress towards a quantitative first-principle continuum approach within the framework of the Functional Renormalization group established by the fQCD collaboration. I focus on recent quantitative results for quenched QCD and Yang-Mills in the vacuum before addressing the calculation of dynamical quantities such as spectral functions and transport coefficients in this framework. (paper)
Dynamic analysis of clustered building structures using substructures methods
International Nuclear Information System (INIS)
Leimbach, K.R.; Krutzik, N.J.
1989-01-01
The dynamic substructure approach to the building cluster on a common base mat starts with the generation of Ritz-vectors for each building on a rigid foundation. The base mat plus the foundation soil is subjected to kinematic constraint modes, for example constant, linear, quadratic or cubic constraints. These constraint modes are also imposed on the buildings. By enforcing kinematic compatibility of the complete structural system on the basis of the constraint modes a reduced Ritz model of the complete cluster is obtained. This reduced model can now be analyzed by modal time history or response spectrum methods
Structure and Dynamics of Interfaces: Drops and Films
Mann, J. Adin, Jr.; Mann, Elizabeth K.; Meyer, William V.; Neumann, A. Wilhelm; Tavana, Hossein
2015-01-01
We aim to acquire measurements of the structure and dynamics of certain liquid-fluid interfaces using an ensemble of techniques in collaboration: (1) Total internal reflection (TIR) Surface light scattering spectroscopy (SLSS), (2) Brewster angle microscopy (BAM), and (3) Drop-shape analysis. SLSS and BAM can be done on a shared interfacial footprint. Results using a 50-50 mixture of pentane-isohexane, which extends the range of NASA's Confined Vapor Bubble (CVB) experiment, yield surface tension results that differ from the expected Langmuir Fit. These results were confirmed using both the SLSS and drop-shape analysis approaches.
Dependence of ICF reaction dynamics on target structure
International Nuclear Information System (INIS)
Kumar, Kamal; Dutt, Sunil; GulI, Muntazir; Ahmad, Tauseef; Rizvi, I.A.; Ali, Sabir; Agarwal, Avinash; Kumar, R.; Chaubey, A.K.
2016-01-01
The projectile structure is also found responsible for the ICF reaction processes. It is found that projectile having bigger alpha cluster is more unstable towards break up. In this context, a comparative study of 12 C and 16 O ion-beams induced reactions with different targets has been done. The deduced ICF contributions for different systems have been plotted against the target charge of different targets. It is observed that target properties may also be responsible for the interplay between CF and ICF reaction dynamics
Dynamical quadrupole structure factor of frustrated ferromagnetic chain
Onishi, Hiroaki
2018-05-01
We investigate the dynamical quadrupole structure factor of a spin-1/2 J1-J2 Heisenberg chain with competing ferromagnetic J1 and antiferromagnetic J2 in a magnetic field by exploiting density-matrix renormalization group techniques. In a field-induced spin nematic regime, we observe gapless excitations at q = π according to quasi-long-range antiferro-quadrupole correlations. The gapless excitation mode has a quadratic form at the saturation, while it changes into a linear dispersion as the magnetization decreases.
Dynamic structurization in solutions of hydrodynamically active polymers
International Nuclear Information System (INIS)
Pogrebnyak, V.G.; Tverdokhleb, S.V.; Naumchuk, N.V.
1993-01-01
The processes of ordering and self-regulation in nonlinear systems have attracted great attention because understanding the principles of self-regulation and its thermodynamics can become a clue to many physical phenomena. In this work, it is experimentally established that, under the condition of elongational flows, dynamic structurization and periodic processes may originate in the solutions of flexible, hydrodynamically-active polymers due to self-regulation in these systems. The hydrodynamic elongational field was created using the flow of a Newtonian liquid (water, acetone, dioxane) converging to a small opening. The hydrodynamically-active polymers were polyethylene oxide or hydrolyzed polyacrylamide
Dynamical measurements of the interior structure of exoplanets
International Nuclear Information System (INIS)
Becker, Juliette C.; Batygin, Konstantin
2013-01-01
Giant gaseous planets often reside on orbits in sufficient proximity to their host stars for the planetary quadrupole gravitational field to become non-negligible. In presence of an additional planetary companion, a precise characterization of the system's orbital state can yield meaningful constraints on the transiting planet's interior structure. However, such methods can require a very specific type of system. This paper explores the dynamic range of applicability of these methods and shows that interior structure calculations are possible for a wide array of orbital architectures. The HAT-P-13 system is used as a case study, and the implications of perturbations arising from a third distant companion on the feasibility of an interior calculation are discussed. We find that the method discussed here is likely to be useful in studying other planetary systems, allowing the possibility of an expanded survey of the interiors of exoplanets.
Proton structure functions in the dipole picture of BFKL dynamics
International Nuclear Information System (INIS)
Navelet, H.; Wallon, S.
1996-06-01
The F 2 , F G , R=F L /F T proton structure functions are derived in the QCD dipole picture. Assuming k T and renormalization-group factorization, we relate deep-inelastic proton scattering to deep-inelastic onium scattering. We get a three-parameter fit of the 1994 H1 data in the low-x, moderate Q 2 range. The ratios F G /F 2 and R are predicted without further adjustment. The dipole picture of BFKL dynamics is shown to provide a relevant model for quantitatively describing the proton structure functions at HERA. The predictions for F 2 and F G are compatible with next-to-leading DGLAP analysis, while R is expected to be significantly lower at very small x. (orig.)
Structural and dynamic properties of solid state ionics
International Nuclear Information System (INIS)
Sakuma, T.
1995-01-01
The structural and dynamic properties of solid state ionics are reviewed. The low temperature phase transition of the copper halide-chalcogen compounds by specific heat measurements, electrical conductivity measurements and x-ray diffraction measurements are explained. The structures of solid state ionics investigated by the usual x-ray diffraction method and the anomalous x-ray scattering (AXS) measurement are discussed. The expression of the diffuse scattering intensity including the correlations among the thermal displacements of atoms has been given and applied to α-AgI type solid state ionics and lithium sulphate. The presence of low-energy excitations in crystalline copper ion conductors and the superionic conducting glass is investigated by neutron inelastic scattering measurements. The relation between the excitation energy and the mass of the cations is discussed. (author). 141 refs., 21 figs., 7 tabs
Parallel processors and nonlinear structural dynamics algorithms and software
Belytschko, Ted
1989-01-01
A nonlinear structural dynamics finite element program was developed to run on a shared memory multiprocessor with pipeline processors. The program, WHAMS, was used as a framework for this work. The program employs explicit time integration and has the capability to handle both the nonlinear material behavior and large displacement response of 3-D structures. The elasto-plastic material model uses an isotropic strain hardening law which is input as a piecewise linear function. Geometric nonlinearities are handled by a corotational formulation in which a coordinate system is embedded at the integration point of each element. Currently, the program has an element library consisting of a beam element based on Euler-Bernoulli theory and trianglar and quadrilateral plate element based on Mindlin theory.
Global structure of exact scalar hairy dynamical black holes
Energy Technology Data Exchange (ETDEWEB)
Fan, Zhong-Ying [Center for High Energy Physics, Peking University,No. 5 Yiheyuan Rd, Beijing, 100871 P.R. (China); Chen, Bin [Center for High Energy Physics, Peking University,No. 5 Yiheyuan Rd, Beijing, 100871 P.R. (China); Department of Physics and State Key Laboratory of Nuclear Physics and Technology,Peking University, No. 5 Yiheyuan Rd, Beijing, 100871 P.R. (China); Collaborative Innovation Center of Quantum Matter,No. 5 Yiheyuan Rd, Beijing, 100871 P.R. (China); Lü, H. [Center for Advanced Quantum Studies, Department of Physics, Beijing Normal University,Beijing, 100875 P.R. (China)
2016-05-30
We study the global structure of some exact scalar hairy dynamical black holes which were constructed in Einstein gravity either minimally or non-minimally coupled to a scalar field. We find that both the apparent horizon and the local event horizon (measured in luminosity coordinate) monotonically increase with the advanced time as well as the Vaidya mass. At late advanced times, the apparent horizon approaches the event horizon and gradually becomes future outer. Correspondingly, the space-time arrives at stationary black hole states with the relaxation time inversely proportional to the 1/(n−1) power of the final black hole mass, where n is the space-time dimension. These results strongly support the solutions describing the formation of black holes with scalar hair. We also obtain new charged dynamical solutions in the non-minimal theory by introducing an Maxwell field which is non-minimally coupled to the scalar. The presence of the electric charge strongly modifies the dynamical evolution of the space-time.
Electrostatic cloaking of surface structure for dynamic wetting
Shiomi, Junichiro; Nita, Satoshi; Do-Quang, Minh; Wang, Jiayu; Chen, Yu-Chung; Suzuki, Yuji; Amberg, Gustav
2017-11-01
Dynamic wetting problems are fundamental to the understanding of the interaction between liquids and solids. Even in a superficially simple experimental situation, such as a droplet spreading over a dry surface, the result may depend not only on the liquid properties but also strongly on the substrate-surface properties; even for macroscopically smooth surfaces, the microscopic geometrical roughness can be important. In addition, as surfaces may often be naturally charged, or electric fields are used to manipulate fluids, electric effects are crucial components that influence wetting phenomena. Here we investigate the interplay between electric forces and surface structures in dynamic wetting. While surface microstructures can significantly hinder the spreading, we find that the electrostatics can ``cloak'' the microstructures, i.e. deactivate the hindering. We identify the physics in terms of reduction in contact-line friction, which makes the dynamic wetting inertial force dominant and insensitive to the substrate properties. This work was financially supported in part by, the Japan Society for the Promotion of Science, Swedish Governmental Agency for Innovation Systems, and the Japan Science and Technology Agency.
Automatic anatomical structures location based on dynamic shape measurement
Witkowski, Marcin; Rapp, Walter; Sitnik, Robert; Kujawinska, Malgorzata; Vander Sloten, Jos; Haex, Bart; Bogaert, Nico; Heitmann, Kjell
2005-09-01
New image processing methods and active photonics apparatus have made possible the development of relatively inexpensive optical systems for complex shape and object measurements. We present dynamic 360° scanning method for analysis of human lower body biomechanics, with an emphasis on the analysis of the knee joint. The anatomical structure (of high medical interest) that is possible to scan and analyze, is patella. Tracking of patella position and orientation under dynamic conditions may lead to detect pathological patella movements and help in knee joint disease diagnosis. The processed data is obtained from a dynamic laser triangulation surface measurement system, able to capture slow to normal movements with a scan frequency between 15 and 30 Hz. These frequency rates are enough to capture controlled movements used e.g. for medical examination purposes. The purpose of the work presented is to develop surface analysis methods that may be used as support of diagnosis of motoric abilities of lower limbs. The paper presents algorithms used to process acquired lower limbs surface data in order to find the position and orientation of patella. The algorithms implemented include input data preparation, curvature description methods, knee region discrimination and patella assumed position/orientation calculation. Additionally, a method of 4D (3D + time) medical data visualization is proposed. Also some exemplary results are presented.
Dynamic multiprotein assemblies shape the spatial structure of cell signaling.
Nussinov, Ruth; Jang, Hyunbum
2014-01-01
Cell signaling underlies critical cellular decisions. Coordination, efficiency as well as fail-safe mechanisms are key elements. How the cell ensures that these hallmarks are at play are important questions. Cell signaling is often viewed as taking place through discrete and cross-talking pathways; oftentimes these are modularized to emphasize distinct functions. While simple, convenient and clear, such models largely neglect the spatial structure of cell signaling; they also convey inter-modular (or inter-protein) spatial separation that may not exist. Here our thesis is that cell signaling is shaped by a network of multiprotein assemblies. While pre-organized, the assemblies and network are loose and dynamic. They contain transiently-associated multiprotein complexes which are often mediated by scaffolding proteins. They are also typically anchored in the membrane, and their continuum may span the cell. IQGAP1 scaffolding protein which binds proteins including Raf, calmodulin, Mek, Erk, actin, and tens more, with actin shaping B-cell (and likely other) membrane-anchored nanoclusters and allosterically polymerizing in dynamic cytoskeleton formation, and Raf anchoring in the membrane along with Ras, provides a striking example. The multivalent network of dynamic proteins and lipids, with specific interactions forming and breaking, can be viewed as endowing gel-like properties. Collectively, this reasons that efficient, productive and reliable cell signaling takes place primarily through transient, preorganized and cooperative protein-protein interactions spanning the cell rather than stochastic, diffusion-controlled processes. Copyright © 2014 Elsevier Ltd. All rights reserved.
Challenges in parameter identification of large structural dynamic systems
International Nuclear Information System (INIS)
Koh, C.G.
2001-01-01
In theory, it is possible to determine the parameters of a structural or mechanical system by subjecting it to some dynamic excitation and measuring the response. Considerable research has been carried out in this subject area known as the system identification over the past two decades. Nevertheless, the challenges associated with numerical convergence are still formidable when the system is large in terms of the number of degrees of freedom and number of unknowns. While many methods work for small systems, the convergence becomes difficult, if not impossible, for large systems. In this keynote lecture, both classical and non-classical system identification methods for dynamic testing and vibration-based inspection are discussed. For classical methods, the extended Kalman filter (EKF) approach is used. On this basis, a substructural identification method has been developed as a strategy to deal with large structural systems. This is achieved by reducing the problem size, thereby significantly improving the numerical convergence and efficiency. Two versions of this method are presented each with its own merits. A numerical example of frame structure with 20 unknown parameters is illustrated. For non-classical methods, the Genetic Algorithm (GA) is shown to be applicable with relative ease due to its 'forward analysis' nature. The computational time is, however, still enormous for large structural systems due to the combinatorial explosion problem. A model GA method has been developed to address this problem and tested with considerable success on a relatively large system of 50 degrees of freedom, accounting for input and output noise effects. An advantages of this GA-based identification method is that the objective function can be defined in response measured. Numerical studies show that the method is relatively robust, as it does in response measured. Numerical studies show that the method is relatively robust, as it dos not require good initial guess and the
Energy Technology Data Exchange (ETDEWEB)
Demontis, Pierfranco; Suffritti, Giuseppe B. [Dipartimento di Chimica e Farmacia, Università degli studi di Sassari, Sassari (Italy); Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali (INSTM), Unità di ricerca di Sassari, Via Vienna, 2, I-07100 Sassari (Italy); Gulín-González, Jorge [Grupo de Matemática y Física Computacionales, Universidad de las Ciencias Informáticas (UCI), Carretera a San Antonio de los Baños, Km 21/2, La Lisa, La Habana (Cuba); Masia, Marco [Dipartimento di Chimica e Farmacia, Università degli studi di Sassari, Sassari (Italy); Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali (INSTM), Unità di ricerca di Sassari, Via Vienna, 2, I-07100 Sassari (Italy); Istituto Officina dei Materiali del CNR, UOS SLACS, Via Vienna 2, 07100 Sassari (Italy); Sant, Marco [Dipartimento di Chimica e Farmacia, Università degli studi di Sassari, Sassari (Italy)
2015-06-28
In order to study the interplay between dynamical heterogeneities and structural properties of bulk liquid water in the temperature range 130–350 K, thus including the supercooled regime, we use the explicit trend of the distribution functions of some molecular properties, namely, the rotational relaxation constants, the atomic mean-square displacements, the relaxation of the cross correlation functions between the linear and squared displacements of H and O atoms of each molecule, the tetrahedral order parameter q and, finally, the number of nearest neighbors (NNs) and of hydrogen bonds (HBs) per molecule. Two different potentials are considered: TIP4P-Ew and a model developed in this laboratory for the study of nanoconfined water. The results are similar for the dynamical properties, but are markedly different for the structural characteristics. In particular, for temperatures higher than that of the dynamic crossover between “fragile” (at higher temperatures) and “strong” (at lower temperatures) liquid behaviors detected around 207 K, the rotational relaxation of supercooled water appears to be remarkably homogeneous. However, the structural parameters (number of NNs and of HBs, as well as q) do not show homogeneous distributions, and these distributions are different for the two water models. Another dynamic crossover between “fragile” (at lower temperatures) and “strong” (at higher temperatures) liquid behaviors, corresponding to the one found experimentally at T{sup ∗} ∼ 315 ± 5 K, was spotted at T{sup ∗} ∼ 283 K and T{sup ∗} ∼ 276 K for the TIP4P-Ew and the model developed in this laboratory, respectively. It was detected from the trend of Arrhenius plots of dynamic quantities and from the onset of a further heterogeneity in the rotational relaxation. To our best knowledge, it is the first time that this dynamical crossover is detected in computer simulations of bulk water. On the basis of the simulation results, the possible
Shekhar, Adarsh
Nanotechnology is becoming increasingly important with the continuing advances in experimental techniques. As researchers around the world are trying to expand the current understanding of the behavior of materials at the atomistic scale, the limited resolution of equipment, both in terms of time and space, act as roadblocks to a comprehensive study. Numerical methods, in general and molecular dynamics, in particular act as able compliment to the experiments in our quest for understanding material behavior. In this research work, large scale molecular dynamics simulations to gain insight into the mechano-chemical behavior under extreme conditions of a variety of systems with many real world applications. The body of this work is divided into three parts, each covering a particular system: 1) Aggregates of aluminum nanoparticles are good solid fuel due to high flame propagation rates. Multi-million atom molecular dynamics simulations reveal the mechanism underlying higher reaction rate in a chain of aluminum nanoparticles as compared to an isolated nanoparticle. This is due to the penetration of hot atoms from reacting nanoparticles to an adjacent, unreacted nanoparticle, which brings in external heat and initiates exothermic oxidation reactions. 2) Cavitation bubbles readily occur in fluids subjected to rapid changes in pressure. We use billion-atom reactive molecular dynamics simulations on a 163,840-processor BlueGene/P supercomputer to investigate chemical and mechanical damages caused by shock-induced collapse of nanobubbles in water near amorphous silica. Collapse of an empty nanobubble generates high-speed nanojet, resulting in the formation of a pit on the surface. The pit contains a large number of silanol groups and its volume is found to be directly proportional to the volume of the nanobubble. The gas-filled bubbles undergo partial collapse and consequently the damage on the silica surface is mitigated. 3) The structure and dynamics of water confined in
Deconstructing continuous flash suppression.
Yang, Eunice; Blake, Randolph
2012-03-08
In this paper, we asked to what extent the depth of interocular suppression engendered by continuous flash suppression (CFS) varies depending on spatiotemporal properties of the suppressed stimulus and CFS suppressor. An answer to this question could have implications for interpreting the results in which CFS influences the processing of different categories of stimuli to different extents. In a series of experiments, we measured the selectivity and depth of suppression (i.e., elevation in contrast detection thresholds) as a function of the visual features of the stimulus being suppressed and the stimulus evoking suppression, namely, the popular "Mondrian" CFS stimulus (N. Tsuchiya & C. Koch, 2005). First, we found that CFS differentially suppresses the spatial components of the suppressed stimulus: Observers' sensitivity for stimuli of relatively low spatial frequency or cardinally oriented features was more strongly impaired in comparison to high spatial frequency or obliquely oriented stimuli. Second, we discovered that this feature-selective bias primarily arises from the spatiotemporal structure of the CFS stimulus, particularly within information residing in the low spatial frequency range and within the smooth rather than abrupt luminance changes over time. These results imply that this CFS stimulus operates by selectively attenuating certain classes of low-level signals while leaving others to be potentially encoded during suppression. These findings underscore the importance of considering the contribution of low-level features in stimulus-driven effects that are reported under CFS.
Dynamical Structure of a Traditional Amazonian Social Network
Directory of Open Access Journals (Sweden)
Paul L. Hooper
2013-11-01
Full Text Available Reciprocity is a vital feature of social networks, but relatively little is known about its temporal structure or the mechanisms underlying its persistence in real world behavior. In pursuit of these two questions, we study the stationary and dynamical signals of reciprocity in a network of manioc beer (Spanish: chicha; Tsimane’: shocdye’ drinking events in a Tsimane’ village in lowland Bolivia. At the stationary level, our analysis reveals that social exchange within the community is heterogeneously patterned according to kinship and spatial proximity. A positive relationship between the frequencies at which two families host each other, controlling for kinship and proximity, provides evidence for stationary reciprocity. Our analysis of the dynamical structure of this network presents a novel method for the study of conditional, or non-stationary, reciprocity effects. We find evidence that short-timescale reciprocity (within three days is present among non- and distant-kin pairs; conversely, we find that levels of cooperation among close kin can be accounted for on the stationary hypothesis alone.
An age structured model for obesity prevalence dynamics in populations
Directory of Open Access Journals (Sweden)
Gilberto González Parra
2010-08-01
Full Text Available Objective. Modeling the correlation of the development of obesity in a population with age and time and predict the dynamics of the correlation of the development of obesity in a population with age and time under different scenarios in Valencia (Spain. Materials and methods. An age structured mathematical model is used to describe the future dynamics of obesity prevalence for different ages in human population with excess weight. Simulation of the model with parameters estimated using the Health Survey of the Region of Valencia 2000 (4.319 interviews and Health Survey of the Region of Valencia 2005 (4.012 interviews. The model considers only overweight and obese populations since these subpopulations are the most relevant on obesity health concern. Results. The model allows predicting and studying the prevalence of obesity for each age. Results showed an increasing trend of obesity in the following years in well accordance with the trend observed in several countries. Conclusions. Based on the numerical simulations it is possible to conclude that the age structured mathematical model is suitable to forecast the obesity epidemic in each age group in different countries. Additionally, this type of models may be applied to study other characteristics of other populations such animal populations.
Structure and dynamics of basin forested wetlands in North America
International Nuclear Information System (INIS)
Brown, S.
1990-01-01
Freshwater basin wetlands are found in depressions of various depths, generally in areas where precipitation exceeds evapotranspiration or where the depression intersects the water table creating groundwater seeps or springs. Forested basins are those that contain woody vegetation with the potential for reaching tree stature; they do not include woody shrub wetlands. In North America these areas are mainly in the central and eastern region. Pertinent information and reviews on the distribution, floristic composition, structure and dynamics of basin forested wetlands are summarized. The major emphasis is on freshwater wetlands, but data for saltwater wetlands mainly from Florida and tropical America are included. The external factors affecting basin wetlands or the important components of a wetlands energy signature are described as well as the distribution and floristic composition of representative basin wetlands. Sections on structural characteristics, organic matter dynamics, and nutrient cycling comprise the bulk of quantitative information. The effects of disturbances, both natural and human induced, with varying degrees of impact depending upon the intensity and on the part of the ecosystem to which the stressor is applied are evaluated. Examples of stressors in basin wetlands include water impoundment, water diversion, thermal stress from hot water, sedimentation, addition of toxic substances, addition of wastewater, oil spills, and harvesting. 86 refs., 5 figs., 11 tabs
Robinson, Lucy F; Atlas, Lauren Y; Wager, Tor D
2015-03-01
We present a new method, State-based Dynamic Community Structure, that detects time-dependent community structure in networks of brain regions. Most analyses of functional connectivity assume that network behavior is static in time, or differs between task conditions with known timing. Our goal is to determine whether brain network topology remains stationary over time, or if changes in network organization occur at unknown time points. Changes in network organization may be related to shifts in neurological state, such as those associated with learning, drug uptake or experimental conditions. Using a hidden Markov stochastic blockmodel, we define a time-dependent community structure. We apply this approach to data from a functional magnetic resonance imaging experiment examining how contextual factors influence drug-induced analgesia. Results reveal that networks involved in pain, working memory, and emotion show distinct profiles of time-varying connectivity. Copyright © 2014 Elsevier Inc. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Kim, Seonghan; Chang, Rakwoo [Kwangwoon University, Seoul (Korea, Republic of)
2016-07-15
Full atomistic molecular dynamics simulations have been performed for model mixture bilayer membrane systems consisting of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) phospholipids to understand the effects of two essential parameters such as lipid composition and temperature on the structural, dynamical, and phase behavior of mixture membrane systems. Although pure DSPC membranes are in the gel-like (L{sub β}' or P{sub β}') phase at 323 K, raising the temperature by only 10 K or replacing 20% of DSPC lipids by DOPC lipids can change the gel-like phase into the completely liquid-crystalline phase (L{sub α}). This phase change is accompanied by dramatic change in both structural properties such as area per lipid, membrane thickness, deuterium order parameter, and tail angle distribution, and dynamics properties such as mobility map. We also observe that the full width at half-maximum (FWHM) data of tail angle distribution as well as area per lipid (or membrane thickness)can be used as order parameters for the membrane phase transition.
International Nuclear Information System (INIS)
Kim, Seonghan; Chang, Rakwoo
2016-01-01
Full atomistic molecular dynamics simulations have been performed for model mixture bilayer membrane systems consisting of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) phospholipids to understand the effects of two essential parameters such as lipid composition and temperature on the structural, dynamical, and phase behavior of mixture membrane systems. Although pure DSPC membranes are in the gel-like (L_β' or P_β') phase at 323 K, raising the temperature by only 10 K or replacing 20% of DSPC lipids by DOPC lipids can change the gel-like phase into the completely liquid-crystalline phase (L_α). This phase change is accompanied by dramatic change in both structural properties such as area per lipid, membrane thickness, deuterium order parameter, and tail angle distribution, and dynamics properties such as mobility map. We also observe that the full width at half-maximum (FWHM) data of tail angle distribution as well as area per lipid (or membrane thickness)can be used as order parameters for the membrane phase transition.
Multiscale molecular dynamics simulation approaches to the structure and dynamics of viruses.
Huber, Roland G; Marzinek, Jan K; Holdbrook, Daniel A; Bond, Peter J
2017-09-01
Viral pathogens are a significant source of human morbidity and mortality, and have a major impact on societies and economies around the world. One of the challenges inherent in targeting these pathogens with drugs is the tight integration of the viral life cycle with the host's cellular machinery. However, the reliance of the virus on the host cell replication machinery is also an opportunity for therapeutic targeting, as successful entry- and exit-inhibitors have demonstrated. An understanding of the extracellular and intracellular structure and dynamics of the virion - as well as of the entry and exit pathways in host and vector cells - is therefore crucial to the advancement of novel antivirals. In recent years, advances in computing architecture and algorithms have begun to allow us to use simulations to study the structure and dynamics of viral ultrastructures at various stages of their life cycle in atomistic or near-atomistic detail. In this review, we outline specific challenges and solutions that have emerged to allow for structurally detailed modelling of viruses in silico. We focus on the history and state of the art of atomistic and coarse-grained approaches to simulate the dynamics of the large, macromolecular structures associated with viral infection, and on their usefulness in explaining and expanding upon experimental data. We discuss the types of interactions that need to be modeled to describe major components of the virus particle and advances in modelling techniques that allow for the treatment of these systems, highlighting recent key simulation studies. Copyright © 2016 Elsevier Ltd. All rights reserved.
Trombetti, Tomaso
This thesis presents an Experimental/Analytical approach to modeling and calibrating shaking tables for structural dynamic applications. This approach was successfully applied to the shaking table recently built in the structural laboratory of the Civil Engineering Department at Rice University. This shaking table is capable of reproducing model earthquake ground motions with a peak acceleration of 6 g's, a peak velocity of 40 inches per second, and a peak displacement of 3 inches, for a maximum payload of 1500 pounds. It has a frequency bandwidth of approximately 70 Hz and is designed to test structural specimens up to 1/5 scale. The rail/table system is mounted on a reaction mass of about 70,000 pounds consisting of three 12 ft x 12 ft x 1 ft reinforced concrete slabs, post-tensioned together and connected to the strong laboratory floor. The slip table is driven by a hydraulic actuator governed by a 407 MTS controller which employs a proportional-integral-derivative-feedforward-differential pressure algorithm to control the actuator displacement. Feedback signals are provided by two LVDT's (monitoring the slip table relative displacement and the servovalve main stage spool position) and by one differential pressure transducer (monitoring the actuator force). The dynamic actuator-foundation-specimen system is modeled and analyzed by combining linear control theory and linear structural dynamics. The analytical model developed accounts for the effects of actuator oil compressibility, oil leakage in the actuator, time delay in the response of the servovalve spool to a given electrical signal, foundation flexibility, and dynamic characteristics of multi-degree-of-freedom specimens. In order to study the actual dynamic behavior of the shaking table, the transfer function between target and actual table accelerations were identified using experimental results and spectral estimation techniques. The power spectral density of the system input and the cross power spectral
Nonlinear dynamic analysis of hydrodynamically-coupled stainless steel structures
International Nuclear Information System (INIS)
Zhao, Y.
1996-01-01
Spent nuclear fuel is usually stored temporarily on the site of nuclear power plants. The spent fuel storage racks are nuclear-safety-related stainless steel structures required to be analyzed for seismic loads. When the storage pool is subjected to three-dimensional (3-D) floor seismic excitations, rack modules, stored fuel bundles, adjacent racks and pool walls, and surrounding water are hydrodynamically coupled. Hydrodynamic coupling (HC) significantly affects the dynamic responses of the racks that are free-standing and submerged in water within the pool. A nonlinear time-history dynamic analysis is usually needed to describe the motion behavior of the racks that are both geometrically nonlinear and material nonlinear in nature. The nonlinearities include the friction resistance between the rack supporting legs and the pool floor, and various potential impacts of fuel-rack, rack-rack, and rack-pool wall. The HC induced should be included in the nonlinear dynamic analysis using the added-hydrodynamic-mass concept based on potential theory per the US Nuclear Regulatory Commission (USNRC) acceptance criteria. To this end, a finite element analysis constitutes a feasible and effective tool. However, most people perform somewhat simplified 1-D, or 2-D, or 3-D single rack and 2-D multiple rack analyses. These analyses are incomplete because a 3-D single rack model behaves quite differently from a 2-D mode. Furthermore, a 3-D whole pool multi-rack model behaves differently than a 3-D single rack model, especially when the strong HC effects are unsymmetrical. In this paper 3-D nonlinear dynamic time-history analyses were performed in a more quantitative manner using sophisticated finite element models developed for a single rack as well as all twelve racks in the whole-pool. Typical response results due to different HC effects are determined and discussed
Shaking of reinforced concrete structures subjected to transient dynamic analysis
International Nuclear Information System (INIS)
Rouzaud, Christophe
2015-01-01
In the design of nuclear engineering structures security and safety present a crucial aspect. Civil engineering design and the qualification of materials to dynamic loads must consider the accelerations which they undergo. These accelerations could integrate seismic activity and shaking movements consecutive to aircraft impact with higher cut-off frequency. Current methodologies for assessing this shock are based on transient analyses using classical finite element method associated with explicit numerical schemes or projection on modal basis, often linear. In both cases, to represent in meaningful way a medium-frequency content, it should implement a mesh refinement which is hardly compatible with the size of models of the civil engineering structures. In order to extend industrial methodologies used and to allow a better representation of the behavior of the structure in medium-frequency, an approach coupling a temporal and non-linear analysis for shock area with a frequency approach to treatment of shaking with VTCR (Variational Theory of Complex Rays) has been used. The aim is to use the computational efficiency of the implemented strategy, including medium frequency to describe the nuclear structures to aircraft impact. (author)
Vesicles and vesicle gels - structure and dynamics of formation
International Nuclear Information System (INIS)
Gradzielski, M
2003-01-01
Vesicles constitute an interesting morphology formed by self-aggregating amphiphilic molecules. They exhibit a rich structural variety and are of interest both from a fundamental point of view (for studying closed bilayer systems) and from a practical point of view (whenever one is interested in the encapsulation of active molecules). In many circumstances vesicular structures have to be formed by external forces, but of great interest are amphiphilic systems, where they form spontaneously. Here the question arises of whether this means that they are also thermodynamically stable structures, which at least in some systems appears to be the case. If such vesicles are well defined in size, it is possible to pack them densely and thereby form vesicle gels that possess highly elastic properties even for relatively low volume fractions of amphiphile. Conditions for the formation and the microstructure of such vesicle gels have been studied in some detail for the case of unilamellar vesicles. Another important and topical issue is the dynamics of vesicle formation/breakdown, as the understanding of the transition process will open the way to a deeper understanding of their stability and also allow controlling of the structures formed, by means of their formation processes. Significant progress in the study of the transformation processes has been achieved, in particular by means of time-resolved scattering experiments. (topical review)
EURDYN, Nonlinear Transient Analysis of Structure with Dynamic Loads
International Nuclear Information System (INIS)
Donea, J.; Giuliani, S.; Halleux, J.P.
1987-01-01
1 - Description of program or function: The EURDYN computer codes are under development at JRC-Ispra since 1973 for the simulation of non- linear dynamic response of fast-reactor components submitted to impulsive loading due to abnormal working conditions. They are thus mainly used in reactor safety analysis but can apply to other fields. Indeed the codes compute the elasto-plastic transient response of 2-D and thin 3-D structures submitted to fast dynamic loading generated by explosions, impacts... and represented by time dependent pressures, concentrated loads and prescribed displacements, or by initial speeds. Two releases of the structural computer codes EURDYN 01 (2-D beams and triangles and axisymmetric conical shells and triangular tori), 02 (axisymmetric and 2-D quadratic iso-parametric elements) and 03 (triangular plate elements) have already been produced in 1976(1) and 1980(2). They include material (elasto-plasticity using the classical flow theory approach) and geometrical (large displacements and rotations treated by a co-rotational technique) nonlinearities. The present version (Release 3) has been completed mid-1982 and is documented in EUR 8357 EN. The new features of Release 3, as compared to the former ones, roughly consist in: - full large strain capability for 9-node iso-parametric elements (EURDYN 02), - generalized array dimensions, - introduction of the radial return algorithm for elasto-plastic material modelling, - extension of the energy check facility to the case of prescribed displacements, - possible interface to a post-processing package including time plot facilities (TPLOT). The theoretical aspects can be found in refs. 2,4,5,6,7,8. 2 - Method of solution: - Finite element space discretization. - Explicit time integration. - Lumped masses. - EURDYN 01: 2-D co-rotational formulation including constant strain triangles (plane or axisymmetric), beams and conical shells, this last element being particularly useful for the study of thin
PCI-SS: MISO dynamic nonlinear protein secondary structure prediction
Directory of Open Access Journals (Sweden)
Aboul-Magd Mohammed O
2009-07-01
Full Text Available Abstract Background Since the function of a protein is largely dictated by its three dimensional configuration, determining a protein's structure is of fundamental importance to biology. Here we report on a novel approach to determining the one dimensional secondary structure of proteins (distinguishing α-helices, β-strands, and non-regular structures from primary sequence data which makes use of Parallel Cascade Identification (PCI, a powerful technique from the field of nonlinear system identification. Results Using PSI-BLAST divergent evolutionary profiles as input data, dynamic nonlinear systems are built through a black-box approach to model the process of protein folding. Genetic algorithms (GAs are applied in order to optimize the architectural parameters of the PCI models. The three-state prediction problem is broken down into a combination of three binary sub-problems and protein structure classifiers are built using 2 layers of PCI classifiers. Careful construction of the optimization, training, and test datasets ensures that no homology exists between any training and testing data. A detailed comparison between PCI and 9 contemporary methods is provided over a set of 125 new protein chains guaranteed to be dissimilar to all training data. Unlike other secondary structure prediction methods, here a web service is developed to provide both human- and machine-readable interfaces to PCI-based protein secondary structure prediction. This server, called PCI-SS, is available at http://bioinf.sce.carleton.ca/PCISS. In addition to a dynamic PHP-generated web interface for humans, a Simple Object Access Protocol (SOAP interface is added to permit invocation of the PCI-SS service remotely. This machine-readable interface facilitates incorporation of PCI-SS into multi-faceted systems biology analysis pipelines requiring protein secondary structure information, and greatly simplifies high-throughput analyses. XML is used to represent the input
Nonlinear dynamic analysis of framed structures including soil-structure interaction effects
International Nuclear Information System (INIS)
Mahmood, M.N.; Ahmed, S.Y.
2008-01-01
The role of oil-structure interaction on seismic behavior of reinforced concrete structures is investigated in this paper. A finite element approach has been adopted to model the interaction system that consists of the reinforced concrete plane frame, soil deposit and interface which represents the frictional between foundation of the structure and subsoil. The analysis is based on the elasto-plastic behavior of the frame members (beams and columns) that is defined by the ultimate axial force-bending moment interaction curve, while the cap model is adopted to govern the elasto-plastic behavior of the soil material. Mohr-Coulomb failure law is used to determine the initiation of slippage at the interface, while the separation is assumed to determine the initiation of slippage at the interface, while the separation is assumed to occur when the stresses at the interface becomes tension stresses. New-Mark's Predictor-Corrector algorithm is adopted for nonlinear dynamic analysis. The main aim of present work is to evaluate the sensitivity of structures to different behavior of the soil and interface layer when subjected to an earthquake excitation. Predicted results of the dynamic analysis of the interaction system indicate that the soil-structure interaction problem can have beneficial effects on the structural behavior when different soil models (elastic and elasto-plastic) and interface conditions (perfect bond and permitted slip)are considered. (author)
Structure and lattice dynamics in non-centrosymmetric borates
International Nuclear Information System (INIS)
Stein, W.D.R.
2007-01-01
This thesis deals with a study of structural and lattice dynamical properties of some noncentrosymmetric borates with outstanding non-linear optical properties. The focus was on the compound bismuth triborate (BiB 3 O 6 ). The structure of the tetraborates MB 4 O 7 (M=Pb,Sr,Ba) was also investigated. The structural investigations in bismuth triborate include powder and single crystal diffraction experiments on X-ray and neutron sources. The crystal structure was under examination in the temperature range from 100 K to room temperature and the lattice constants in the temperature range from 20 K to 800 K. The lattice constants show a nearly linear dependency from temperature. Our observations are in good agreement with investigations of the thermal expansion, which shows a strong anisotropy within the layer-like structure of bismuth triborate. Within the borate layers, along the polar axis a strong positive and in the orthogonal direction a negative thermal expansion is observed. This effect can be explained by a zig-zag effect within the borate layers. The lone electron pair at the bismuth atom is discussed to be possibly the origin of the temperature dependency of the coordination environment of the bismuth atom. The influence of the lone electron pair on the crystal structure is raising by lowering the temperature. At the bismuth atom distinct anharmonic effects are observed, where the maximum points along the direction of the polar axis and therefore along the direction of the lone electron pair. The phonon dispersion of bismuth triborate has been investigated by inelastic neutron scattering. The low symmetry of the crystal structure depicts to be a special challenge. The dispersion was observed along the three reciprocal lattice constants. Along the polar axis the dispersion could be characterized to a maximum energy of 20 THz. The low energy acoustic branch along the polar axis shows a softening at the zone boundary. In the orthogonal directions the dispersion
Nonlinear dynamics of drift structures in a magnetized dissipative plasma
International Nuclear Information System (INIS)
Aburjania, G. D.; Rogava, D. L.; Kharshiladze, O. A.
2011-01-01
A study is made of the nonlinear dynamics of solitary vortex structures in an inhomogeneous magnetized dissipative plasma. A nonlinear transport equation for long-wavelength drift wave structures is derived with allowance for the nonuniformity of the plasma density and temperature equilibria, as well as the magnetic and collisional viscosity of the medium and its friction. The dynamic equation describes two types of nonlinearity: scalar (due to the temperature inhomogeneity) and vector (due to the convectively polarized motion of the particles of the medium). The equation is fourth order in the spatial derivatives, in contrast to the second-order Hasegawa-Mima equations. An analytic steady solution to the nonlinear equation is obtained that describes a new type of solitary dipole vortex. The nonlinear dynamic equation is integrated numerically. A new algorithm and a new finite difference scheme for solving the equation are proposed, and it is proved that the solution so obtained is unique. The equation is used to investigate how the initially steady dipole vortex constructed here behaves unsteadily under the action of the factors just mentioned. Numerical simulations revealed that the role of the vector nonlinearity is twofold: it helps the dispersion or the scalar nonlinearity (depending on their magnitude) to ensure the mutual equilibrium and, thereby, promote self-organization of the vortical structures. It is shown that dispersion breaks the initial dipole vortex into a set of tightly packed, smaller scale, less intense monopole vortices-alternating cyclones and anticyclones. When the dispersion of the evolving initial dipole vortex is weak, the scalar nonlinearity symmetrically breaks a cyclone-anticyclone pair into a cyclone and an anticyclone, which are independent of one another and have essentially the same intensity, shape, and size. The stronger the dispersion, the more anisotropic the process whereby the structures break: the anticyclone is more intense
Structural phase transition and dynamical properties of PbTiO3 simulated by molecular dynamics
International Nuclear Information System (INIS)
Costa, S C; Pizani, P S; Rino, J P; Borges, D S
2005-01-01
The temperature- and pressure-induced structural phase transition in PbTiO 3 is studied with the isoenthalpic-isobaric molecular-dynamics method, using an effective two-body interaction potential. The tetragonal to cubic transformation is successfully reproduced with both temperature and pressure. The behaviour of lattice parameters, vibrational density of states, and phonon anharmonicity with temperature and pressure are in very good agreement with experimental data. Two- and three-body correlations were analysed through pair distribution functions, coordination numbers and bond-angle distributions
Excimer Formation Dynamics of Dipyrenyldecane in Structurally Different Ionic Liquids.
Yadav, Anita; Pandey, Siddharth
2017-12-07
Ionic liquids, being composed of ions alone, may offer alternative pathways for molecular aggregation. These pathways could be controlled by the chemical structure of the cation and the anion of the ionic liquids. Intramolecular excimer formation dynamics of a bifluorophoric probe, 1,3-bis(1-pyrenyl)decane [1Py(10)1Py], where the fluorophoric pyrene moieties are separated by a long decyl chain, is investigated in seven different ionic liquids in 10-90 °C temperature range. The long alkyl separator allows for ample interaction with the solubilizing milieu prior to the formation of the excimer. The ionic liquids are composed of two sets, one having four ionic liquids of 1-butyl-3-methylimidazolium cation ([bmim + ]) with different anions and the other having four ionic liquids of bis(trifluoromethylsulfonyl)imide anion ([Tf 2 N - ]) with different cations. The excimer-to-monomer emission intensity ratio (I E /I M ) is found to increase with increasing temperature in sigmoidal fashion. Chemical structure of the ionic liquid controls the excimer formation efficiency, as I E /I M values within ionic liquids with the same viscosities are found to be significantly different. The excited-state intensity decay kinetics of 1Py(10)1Py in ionic liquids do not adhere to a simplistic Birk's scheme, where only one excimer conformer forms after excitation. The apparent rate constants of excimer formation (k a ) in highly viscous ionic liquids are an order of magnitude lower than those reported in organic solvents. In general, the higher the viscosity of the ionic liquid, the more sensitive is the k a to the temperature with higher activation energy, E a . The trend in E a is found to be similar to that for activation energy of the viscous flow (E a,η ). Stokes-Einstein relationship is not followed in [bmim + ] ionic liquids; however, with the exception of [choline][Tf 2 N], it is found to be followed in [Tf 2 N - ] ionic liquids suggesting the cyclization dynamics of 1Py(10)1Py
Directory of Open Access Journals (Sweden)
Jian Hao
2017-10-01
Full Text Available Cellulose insulation polymer (paper/pressboard has been widely used in high voltage direct current (HVDC transformers. One of the most challenging issues in the insulation material used for HVDC equipment is the space charge accumulation. Effective ways to suppress the space charge injection/accumulation in insulation material is currently a popular research topic. In this study, an aluminium oxide functional film was deposited on a cellulose insulation pressboard surface using reactive radio frequency (RF magnetron sputtering. The sputtered thin film was characterized by the scanning electron microscopy/energy dispersive spectrometer (SEM/EDS, X-ray photoelectron spectroscopy (XPS, and X-ray diffraction (XRD. The influence of the deposited functional film on the dielectric properties and the space charge injection/accumulation behaviour was investigated. A preliminary exploration of the space charge suppression effect is discussed. SEM/EDS, XPS, and XRD results show that the nano-structured Al2O3 film with amorphous phase was successfully fabricated onto the fibre surface. The cellulose insulation pressboard surface sputtered by Al2O3 film has lower permittivity, conductivity, and dissipation factor values in the lower frequency (<103 Hz region. The oil-impregnated sputtered pressboard presents an apparent space-charge suppression effect. Compared with the pressboard sputtered with Al2O3 film for 90 min, the pressboard sputtered with Al2O3 film for 60 min had a better space charge suppression effect. Ultra-small Al2O3 particles (<10 nm grew on the surface of the larger nanoparticles. The nano-structured Al2O3 film sputtered on the fibre surface could act as a functional barrier layer for suppression of the charge injection and accumulation. This study offers a new perspective in favour of the application of insulation pressboard with a nano-structured function surface against space charge injection/accumulation in HVDC equipment.
Dynamical X-ray scattering from the relaxed structures
International Nuclear Information System (INIS)
Benediktovitch, A.; Feranchuk, I.; Ulyanenkov, A.
2009-01-01
High-resolution X-ray diffraction is now widely used analytical tool for investigation of nano scale multilayered structures in semiconductor and optical technologies. The HRXRD method delivers unique information on the crystallographic lattice of the samples, concentration of solid solutions, lattice mismatches, layer thicknesses, defect distribution, and relaxation degree of the epitaxial layers. The evaluation of the experimental results, however, requires a robust and precise theory due to complex dynamical scattering of X-rays from near perfect crystallographic structure of the samples. Usually, the Takagi-Taupin approach [1] or the recurrent matrix methods [2] are used for the simulation of the X-ray diffraction profiles from the epitaxial multilayered structures. The use of these theories, however, becomes essentially difficult, when the lateral lattice mismatches are present in multilayers, for example, in the case of partially or fully relaxed epitaxially grown samples. In the present work, the general solution of this problem is found analytically. The angular divergence of the incident beam is also considered and the algorithm for the diffracted profile mapping in the reciprocal space is developed. The experimental reciprocal space mapping of typical AlGaN/GaN/AlN samples with partially relaxed layers is compared to the simulated maps, which describe well the location and character of the diffraction spots caused by different layers. (author)
Directory of Open Access Journals (Sweden)
Komarine Romdenh-Romluc
2009-12-01
Full Text Available Moran’s revised conception of conscious belief requires us to reconceptualise suppressed belief. The work of Merleau-Ponty offers a way to do this. His account of motor-skills allows us to understand suppressed beliefs as pre-reflective ways of dealing with the world.
Structure and dynamics at the liquid surface of benzyl alcohol
International Nuclear Information System (INIS)
Dietter, J.; Morgner, H.
1999-01-01
A molecular dynamics simulation of a liquid layer of benzyl alcohol has been performed in order to compare the results with those obtained in experimental studies of our group. The main result of the experimental work was a strong orientational ordering of the benzyl alcohol molecules in the surface as well as an exceptionally large surface potential of ca. 0.6 V. According to the experiments the surface molecules orientate in such a way that the benzene ring points toward the vapor phase while the CH 2 group and the OH group are directed towards the bulk of the liquid. The simulation confirms this orientation of the surface molecules. The surface potential resulting from the simulation is 350 mV. The simulation reveals that the rather large surface potential can be understood as a consequence of the mean orientation of the molecular dipole moment in the surface region. The mean orientation of the molecules themselves in the surface is due to the tendency of the system to maintain the hydrogen bonding structure of the bulk in the surface region as well. The preferential orientation of the surface molecules causes a change of the dynamics of the individual components of the molecules when switching from bulk to surface which depends on the separation of these components from the polar group. This becomes most obvious in case of the reorientation dynamics of the molecular axes, e.g. the reorientation of the benzene ring is faster than the reorientation of the OH group. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)
Jablonski, Piotr; Poe, Gina; Zochowski, Michal
2007-03-01
The hippocampus has the capacity for reactivating recently acquired memories and it is hypothesized that one of the functions of sleep reactivation is the facilitation of consolidation of novel memory traces. The dynamic and network processes underlying such a reactivation remain, however, unknown. We show that such a reactivation characterized by local, self-sustained activity of a network region may be an inherent property of the recurrent excitatory-inhibitory network with a heterogeneous structure. The entry into the reactivation phase is mediated through a physiologically feasible regulation of global excitability and external input sources, while the reactivated component of the network is formed through induced network heterogeneities during learning. We show that structural changes needed for robust reactivation of a given network region are well within known physiological parameters.
Importance of structural damping in the dynamic analysis of compliant deployable structures
Dewalque, Florence; Rochus, Pierre; Brüls, Olivier
2015-06-01
Compliant mechanisms such as tape springs are often used on satellites to deploy appendices, e.g. solar panels, antennas, telescopes and solar sails. Their main advantage comes from the fact that their motion results from the elastic deformation of structural components and the absence of actuators or external energy sources. The mechanical behaviour of a tape spring is intrinsically complex and nonlinear involving buckling, hysteresis and self-locking phenomena. In the majority of the previous works, dynamic simulations were performed without any physical representation of the structural damping. These simulations could be successfully achieved because of the presence of numerical damping in the transient solver. However, in this case, the dynamic response turns out to be quite sensitive to the amount of numerical dissipation, so that the predictive capabilities of the model are questionable. In this work based on numerical case studies, we show that the dynamic simulation of a tape spring can be made less sensitive to numerical parameters when the structural dissipation is taken into account.
Mean-field theory of nuclear structure and dynamics
International Nuclear Information System (INIS)
Negele, J.W.
1982-01-01
The physical and theoretical foundations are presented for the mean-field theory of nuclear structure and dynamics. Salient features of the many-body theory of stationary states are reviewed to motivate the time-dependent mean-field approximation. The time-dependent Hartree-Fock approximation and its limitations are discussed and general theoretical formulations are presented which yield time-dependent mean-field equations in lowest approximation and provide suitable frameworks for overcoming various conceptual and practical limitations of the mean-field theory. Particular emphasis is placed on recent developments utilizing functional integral techniques to obtain a quantum mean-field theory applicable to quantized eigenstates, spontaneous fission, the nuclear partition function, and scattering problems. Applications to a number of simple, idealized systems are presented to verify the approximations for solvable problems and to elucidate the essential features of mean-field dynamics. Finally, calculations utilizing moderately realistic geometries and interactions are reviewed which address heavy-ion collisions, fusion, strongly damped collisions, and fission
The Influence of Knitting Structure on Heating and Cooling Dynamic
Directory of Open Access Journals (Sweden)
Daiva MIKUČIONIENĖ
2013-05-01
Full Text Available The comfort provided by clothing depends on several factors, one of them being thermal comfort. Human thermal comfort depends on a combination of clothing, climate, and physical activity. It is known, the fibre type, yarn properties, fabric structure, finishing are the main factors affecting thermo-physiological comfort. The thermal property of knitted fabric is very important not only for its thermal comfort but also for protection against cross weather conditions. Most of the studies carried out have been devoted to measure static thermal properties. But it is very important not only amount of the heat released to the environment but also the dynamics of the heat transmission. The main goal of this work was to investigate the dynamic of the heat and cool transfer through the fabrics with different knitting pattern and different type of the yarns. Three different types of knitted fabrics were developed for this experimental work.DOI: http://dx.doi.org/10.5755/j01.ms.19.2.4434
Coding considerations for standalone molecular dynamics simulations of atomistic structures
Ocaya, R. O.; Terblans, J. J.
2017-10-01
The laws of Newtonian mechanics allow ab-initio molecular dynamics to model and simulate particle trajectories in material science by defining a differentiable potential function. This paper discusses some considerations for the coding of ab-initio programs for simulation on a standalone computer and illustrates the approach by C language codes in the context of embedded metallic atoms in the face-centred cubic structure. The algorithms use velocity-time integration to determine particle parameter evolution for up to several thousands of particles in a thermodynamical ensemble. Such functions are reusable and can be placed in a redistributable header library file. While there are both commercial and free packages available, their heuristic nature prevents dissection. In addition, developing own codes has the obvious advantage of teaching techniques applicable to new problems.
Direct Adaptive Aircraft Control Using Dynamic Cell Structure Neural Networks
Jorgensen, Charles C.
1997-01-01
A Dynamic Cell Structure (DCS) Neural Network was developed which learns topology representing networks (TRNS) of F-15 aircraft aerodynamic stability and control derivatives. The network is integrated into a direct adaptive tracking controller. The combination produces a robust adaptive architecture capable of handling multiple accident and off- nominal flight scenarios. This paper describes the DCS network and modifications to the parameter estimation procedure. The work represents one step towards an integrated real-time reconfiguration control architecture for rapid prototyping of new aircraft designs. Performance was evaluated using three off-line benchmarks and on-line nonlinear Virtual Reality simulation. Flight control was evaluated under scenarios including differential stabilator lock, soft sensor failure, control and stability derivative variations, and air turbulence.
13C-NMR assignment, structure, and dynamics of deoxyoligonucleotides
International Nuclear Information System (INIS)
Zanatta, N.; Borer, P.N.; Levy, G.C.
1986-01-01
The unique spectral properties of 13 C-NMR for studying nucleic acids and some of the important features of 13 C-NMR in oligonucleotide studies are demostrated. The main difficulty in studying oligonucleotides by 13 C-NMR and recent improvements in NMR instrumentation and advances in oligonucleotide synthesis are presented. The high resolution 13 C-NMR spectra, T 1 relaxation times and NOEs were measured for duplex of the self-complementary oligo-DNAs: d(CG) 3 and d(GGTATACC) are studied. The target of this study is to developed a systematic 13 C-NMR spectral assignment and to investigate the structure and dynamics of these two sequences by this techniques. (M.J.C.) [pt
Structure and Dynamics of Quasi-Ordered Systems
International Nuclear Information System (INIS)
Eckert, J.; Redondo, A.; Henson, N.J.; Wang, W.; Hay, P.J.
1999-01-01
The functionality of many materials of both fundamental and technological interest is often critically dependent on the nature and extent of any disorder that may be present. In addition, it is often difficult to understand the nature of disorder in quite well ordered systems. There is therefore an urgent need to develop better tools, both experimental and computational, for the study of such quasi-ordered systems. To this end, the authors have used neutron diffraction studies in an attempt to locate small metal clusters or molecules randomly distributed inside microporous catalytic materials. Specifically, they have used pair distribution function (PDF) analysis, as well as inelastic neutron scattering (INS) spectroscopy, to study interactions between adsorbate molecules and a microporous matrix. They have interfaced these experimental studies with computations of PDF analysis as well as modeling of the dynamics of adsorbates. These techniques will be invaluable in elucidating the local structure and function of many of these classes of materials
Dynamic control of quadruped robot with hierarchical control structure
International Nuclear Information System (INIS)
Wang, Yu-Zhang; Furusho, Junji; Okajima, Yosuke.
1988-01-01
For moving on irregular terrain, such as the inside of a nuclear power plant and outer space, it is generally recognized that the multilegged walking robot is suitable. This paper proposes a hierarchical control structure for the dynamic control of quadruped walking robots. For this purpose, we present a reduced order model which can approximate the original higher order model very well. Since this reduced order model does not require much computational time, it can be used in the real-time control of a quadruped walking robot. A hierarchical control experiment is shown in which the optimal control algorithm using a reduced order model is calculated by one microprocessor, and the other control algorithm is calculated by another microprocessor. (author)
Parameter identification for structural dynamics based on interval analysis algorithm
Yang, Chen; Lu, Zixing; Yang, Zhenyu; Liang, Ke
2018-04-01
A parameter identification method using interval analysis algorithm for structural dynamics is presented in this paper. The proposed uncertain identification method is investigated by using central difference method and ARMA system. With the help of the fixed memory least square method and matrix inverse lemma, a set-membership identification technology is applied to obtain the best estimation of the identified parameters in a tight and accurate region. To overcome the lack of insufficient statistical description of the uncertain parameters, this paper treats uncertainties as non-probabilistic intervals. As long as we know the bounds of uncertainties, this algorithm can obtain not only the center estimations of parameters, but also the bounds of errors. To improve the efficiency of the proposed method, a time-saving algorithm is presented by recursive formula. At last, to verify the accuracy of the proposed method, two numerical examples are applied and evaluated by three identification criteria respectively.
The landscape of nonlinear structural dynamics: an introduction.
Butlin, T; Woodhouse, J; Champneys, A R
2015-09-28
Nonlinear behaviour is ever-present in vibrations and other dynamical motions of engineering structures. Manifestations of nonlinearity include amplitude-dependent natural frequencies, buzz, squeak and rattle, self-excited oscillation and non-repeatability. This article primarily serves as an extended introduction to a theme issue in which such nonlinear phenomena are highlighted through diverse case studies. More ambitiously though, there is another goal. Both the engineering context and the mathematical techniques that can be used to identify, analyse, control or exploit these phenomena in practice are placed in the context of a mind-map, which has been created through expert elicitation. This map, which is available in software through the electronic supplementary material, attempts to provide a practitioner's guide to what hitherto might seem like a vast and complex research landscape. © 2015 The Authors.
Jang, Mooseok; Ruan, Haowen; Vellekoop, Ivo M.; Judkewitz, Benjamin; Chung, Euiheon; Yang, Changhuei
2014-01-01
Light scattering in biological tissue significantly limits the accessible depth for localized optical interrogation and deep-tissue optical imaging. This challenge can be overcome by exploiting the time-reversal property of optical phase conjugation (OPC) to reverse multiple scattering events or suppress turbidity. However, in living tissue, scatterers are highly movable and the movement can disrupt time-reversal symmetry when there is a latency in the OPC playback. In this paper, we show that the motion-induced degradation of the OPC turbidity-suppression effect through a dynamic scattering medium shares the same decorrelation time constant as that determined from speckle intensity autocorrelation – a popular conventional measure of scatterer movement. We investigated this decorrelation characteristic time through a 1.5-mm-thick dorsal skin flap of a living mouse and found that it ranges from 50 ms to 2.5 s depending on the level of immobilization. This study provides information on relevant time scales for applying OPC to living tissues. PMID:25657876
Nonlinear dynamic soil-structure interaction in earthquake engineering
International Nuclear Information System (INIS)
Nieto-Ferro, Alex
2013-01-01
The present work addresses a computational methodology to solve dynamic problems coupling time and Laplace domain discretizations within a domain decomposition approach. In particular, the proposed methodology aims at meeting the industrial need of performing more accurate seismic risk assessments by accounting for three-dimensional dynamic soil-structure interaction (DSSI) in nonlinear analysis. Two subdomains are considered in this problem. On the one hand, the linear and unbounded domain of soil which is modelled by an impedance operator computed in the Laplace domain using a Boundary Element (BE) method; and, on the other hand, the superstructure which refers not only to the structure and its foundations but also to a region of soil that possibly exhibits nonlinear behaviour. The latter sub-domain is formulated in the time domain and discretized using a Finite Element (FE) method. In this framework, the DSSI forces are expressed as a time convolution integral whose kernel is the inverse Laplace transform of the soil impedance matrix. In order to evaluate this convolution in the time domain by means of the soil impedance matrix (available in the Laplace domain), a Convolution Quadrature-based approach called the Hybrid Laplace-Time domain Approach (HLTA), is thus introduced. Its numerical stability when coupled to Newmark time integration schemes is subsequently investigated through several numerical examples of DSSI applications in linear and nonlinear analyses. The HLTA is finally tested on a more complex numerical model, closer to that of an industrial seismic application, and good results are obtained when compared to the reference solutions. (author)
Dynamical versus diffraction spectrum for structures with finite local complexity
Baake, Michael; Lenz, Daniel; van Enter, Aernout
2015-01-01
It is well known that the dynamical spectrum of an ergodic measure dynamical system is related to the diffraction measure of a typical element of the system. This situation includes ergodic subshifts from symbolic dynamics as well as ergodic Delone dynamical systems, both via suitable embeddings.
Directory of Open Access Journals (Sweden)
Kei Moritsugu
Full Text Available Molecular dynamics (MD simulations of proteins provide important information to understand their functional mechanisms, which are, however, likely to be hidden behind their complicated motions with a wide range of spatial and temporal scales. A straightforward and intuitive analysis of protein dynamics observed in MD simulation trajectories is therefore of growing significance with the large increase in both the simulation time and system size. In this study, we propose a novel description of protein motions based on the hierarchical clustering of fluctuations in the inter-atomic distances calculated from an MD trajectory, which constructs a single tree diagram, named a "Motion Tree", to determine a set of rigid-domain pairs hierarchically along with associated inter-domain fluctuations. The method was first applied to the MD trajectory of substrate-free adenylate kinase to clarify the usefulness of the Motion Tree, which illustrated a clear-cut dynamics picture of the inter-domain motions involving the ATP/AMP lid and the core domain together with the associated amplitudes and correlations. The comparison of two Motion Trees calculated from MD simulations of ligand-free and -bound glutamine binding proteins clarified changes in inherent dynamics upon ligand binding appeared in both large domains and a small loop that stabilized ligand molecule. Another application to a huge protein, a multidrug ATP binding cassette (ABC transporter, captured significant increases of fluctuations upon binding a drug molecule observed in both large scale inter-subunit motions and a motion localized at a transmembrane helix, which may be a trigger to the subsequent structural change from inward-open to outward-open states to transport the drug molecule. These applications demonstrated the capabilities of Motion Trees to provide an at-a-glance view of various sizes of functional motions inherent in the complicated MD trajectory.
Nonlinear analysis and dynamic structure in the energy market
Aghababa, Hajar
This research assesses the dynamic structure of the energy sector of the aggregate economy in the context of nonlinear mechanisms. Earlier studies have focused mainly on the price of the energy products when detecting nonlinearities in time series data of the energy market, and there is little mention of the production side of the market. Moreover, there is a lack of exploration about the implication of high dimensionality and time aggregation when analyzing the market's fundamentals. This research will address these gaps by including the quantity side of the market in addition to the price and by systematically incorporating various frequencies for sample sizes in three essays. The goal of this research is to provide an inclusive and exhaustive examination of the dynamics in the energy markets. The first essay begins with the application of statistical techniques, and it incorporates the most well-known univariate tests for nonlinearity with distinct power functions over alternatives and tests different null hypotheses. It utilizes the daily spot price observations on five major products in the energy market. The results suggest that the time series daily spot prices of the energy products are highly nonlinear in their nature. They demonstrate apparent evidence of general nonlinear serial dependence in each individual series, as well as nonlinearity in the first, second, and third moments of the series. The second essay examines the underlying mechanism of crude oil production and identifies the nonlinear structure of the production market by utilizing various monthly time series observations of crude oil production: the U.S. field, Organization of the Petroleum Exporting Countries (OPEC), non-OPEC, and the world production of crude oil. The finding implies that the time series data of the U.S. field, OPEC, and the world production of crude oil exhibit deep nonlinearity in their structure and are generated by nonlinear mechanisms. However, the dynamics of the non
Femtosecond structural dynamics on the atomic length scale
Energy Technology Data Exchange (ETDEWEB)
Zhang, Dongfang
2014-03-15
This thesis reports on the development and application of two different but complementary ultrafast electron diffraction setups built at the Max Planck Research Department for Structural Dynamics. One is an ultra-compact femtosecond electron diffraction (FED) setup (Egun300), which is currently operational (with a maximum electron energy of 150 keV) and provides ultrashort (∝300 fs) and bright (∝10 e/μm{sup 2}) electron bunches. The other one, named as Relativistic Electron Gun for Atomic Exploration (REGAE) is a radio frequency driven 2 to 5 MeV FED setup built in collaboration with different groups from DESY. REGAE was developed as a facility that will provide high quality diffraction with sufficient coherence to even address structural protein dynamics and with electron pulses as short as 20 fs (FWHM). As one of the first students in Prof. R.J. Dwayne Miller's group, I led the femtosecond (fs) laser sub-group at REGAE being responsible for the construction of different key optical elements required to drive both of aforementioned FED systems. A third harmonic generation (THG) and a nonlinear optical parametric amplifier (NOPA) have been used for the photo-generation of ultrashort electron bursts as well as sample laser excitation. Different diagnostic tools have been constructed to monitor the performance of the fs optical system. A fast autocorrelator was developed to provide on the fly pulse duration correction. A transient-grating frequency-resolved optical gating (TG-FROG) was built to obtain detail information about the characteristics of fs optical pulse, i.e. phase and amplitude of its spectral components. In addition to these optical setups, I developed a fs optical pump-probe system, which supports broadband probe pulses. This setup was successfully applied to investigate the semiconductor-to-metal photoinduced phase transition in VO{sub 2} and the ultrafast photo-reduction mechanism of graphene oxide. In regard to FED setups, I have been
Femtosecond structural dynamics on the atomic length scale
International Nuclear Information System (INIS)
Zhang, Dongfang
2014-03-01
This thesis reports on the development and application of two different but complementary ultrafast electron diffraction setups built at the Max Planck Research Department for Structural Dynamics. One is an ultra-compact femtosecond electron diffraction (FED) setup (Egun300), which is currently operational (with a maximum electron energy of 150 keV) and provides ultrashort (∝300 fs) and bright (∝10 e/μm 2 ) electron bunches. The other one, named as Relativistic Electron Gun for Atomic Exploration (REGAE) is a radio frequency driven 2 to 5 MeV FED setup built in collaboration with different groups from DESY. REGAE was developed as a facility that will provide high quality diffraction with sufficient coherence to even address structural protein dynamics and with electron pulses as short as 20 fs (FWHM). As one of the first students in Prof. R.J. Dwayne Miller's group, I led the femtosecond (fs) laser sub-group at REGAE being responsible for the construction of different key optical elements required to drive both of aforementioned FED systems. A third harmonic generation (THG) and a nonlinear optical parametric amplifier (NOPA) have been used for the photo-generation of ultrashort electron bursts as well as sample laser excitation. Different diagnostic tools have been constructed to monitor the performance of the fs optical system. A fast autocorrelator was developed to provide on the fly pulse duration correction. A transient-grating frequency-resolved optical gating (TG-FROG) was built to obtain detail information about the characteristics of fs optical pulse, i.e. phase and amplitude of its spectral components. In addition to these optical setups, I developed a fs optical pump-probe system, which supports broadband probe pulses. This setup was successfully applied to investigate the semiconductor-to-metal photoinduced phase transition in VO 2 and the ultrafast photo-reduction mechanism of graphene oxide. In regard to FED setups, I have been deeply involved in
Simulations of the structure and dynamics of nanoparticle-based ionic liquids
Hong, Bingbing; Chremos, Alexandros; Panagiotopoulos, Athanassios Z.
2012-01-01
We use molecular dynamics simulations over microsecond time scales to study the structure and dynamics of coarse-grained models for nanoparticle-based ionic liquids. The systems of interest consist of particles with charged surface groups and linear
National Research Council Canada - National Science Library
Kalia, Rajiv
1997-01-01
Large-scale molecular-dynamics (MD) simulations were performed to investigate: (1) sintering process, structural correlations, and mechanical behavior including dynamic fracture in microporous and nanophase Si3N4...
Modeling the Effect of Fluid-Structure Interaction on the Impact Dynamics of Pressurized Tank Cars
2009-11-13
This paper presents a computational framework that : analyzes the effect of fluid-structure interaction (FSI) on the : impact dynamics of pressurized commodity tank cars using the : nonlinear dynamic finite element code ABAQUS/Explicit. : There exist...
Analysis of Dynamic Properties of Piezoelectric Structure under Impact Load
Directory of Open Access Journals (Sweden)
Taotao Zhang
2015-10-01
Full Text Available An analytical model of the dynamic properties is established for a piezoelectric structure under impact load, without considering noise and perturbations in this paper. Based on the general theory of piezo-elasticity and impact mechanics, the theoretical solutions of the mechanical and electrical fields of the smart structure are obtained with the standing and traveling wave methods, respectively. The comparisons between the two methods have shown that the standing wave method is better for studying long-time response after an impact load. In addition, good agreements are found between the theoretical and the numerical results. To simulate the impact load, both triangle and step pulse loads are used and comparisons are given. Furthermore, the influence of several parameters is discussed so as to provide some advices for practical use. It can be seen that the proposed analytical model would benefit, to some extent, the design and application (especially the airport runway of the related smart devices by taking into account their impact load performance.
Structural organisation and dynamics in king penguin colonies
Gerum, Richard; Richter, Sebastian; Fabry, Ben; Le Bohec, Céline; Bonadonna, Francesco; Nesterova, Anna; Zitterbart, Daniel P.
2018-04-01
During breeding, king penguins do not build nests, however they show strong territorial behaviour and keep a pecking distance to neighbouring penguins. Penguin positions in breeding colonies are highly stable over weeks and appear regularly spaced, but thus far no quantitative analysis of the structural order inside a colony has been performed. In this study, we use the radial distribution function to analyse the spatial coordinates of penguin positions. Coordinates are obtained from aerial images of two colonies that were observed for several years. Our data demonstrate that the structural order in king penguin colonies resembles a 2D liquid of particles with a Lennard-Jones-type interaction potential. We verify this using a molecular dynamics simulation with thermally driven particles, whereby temperature corresponds to penguin movements, the energy well depth ɛ of the attractive potential corresponds to the strength of the colony-forming behaviour, and the repulsive zone corresponds to the pecking radius. We can recapitulate the liquid disorder of the colony, as measured by the radial distribution function, when the particles have a temperature of several (1.4–10) \
Measurement of resistance switching dynamics in copper sulfide memristor structures
McCreery, Kaitlin; Olson, Matthew; Teitsworth, Stephen
Resistance switching materials are the subject of current research in large part for their potential to enable novel computing devices and architectures such as resistance random access memories and neuromorphic chips. A common feature of memristive structures is the hysteretic switching between high and low resistance states which is induced by the application of a sufficiently large electric field. Here, we describe a relatively simple wet chemistry process to fabricate Cu2 S / Cu memristive structures with Cu2 S film thickness ranging up to 150 micron. In this case, resistance switching is believed to be mediated by electromigration of Cu ions from the Cu substrate into the Cu2 S film. Hysteretic current-voltage curves are measured and reveal switching voltages of about 0.8 Volts with a relatively large variance and independent of film thickness. In order to gain insight into the dynamics and variability of the switching process, we have measured the time-dependent current response to voltage pulses of varying height and duration with a time resolution of 1 ns. The transient response consists of a deterministic RC component as well as stochastically varying abrupt current steps that occur within a few microseconds of the pulse application.
Telemetered sensors for dynamic activity and structural performance monitoring
Townsend, Christopher P.; Hamel, Michael J.; Arms, Steven W.
2001-08-01
The development of improved structures requires knowledge of their dynamic behavior. Minimally intrusive wireless systems, capable of monitoring vibration and impact, are needed in order to provide this knowledge. Our objective was to design, build, and test a high speed data collection and wireless data communications system, including microsensors, and capable of being embedded or externally worn. Our previous transmitter designs were small and could be used to transmit multichannel digital data, but they were not capable of fast data transmission rates. The addition of a remotely triggered datalogger allowed us to overcome the limitations of our earlier designs. A bi-directional RF communications link was used to trigger a sample to be logged (from 30 meters), as well as to request data to be transmitted to the host PC for data acquisition/analysis. Sweep rates of 2000 Hz were successfully demonstrated from a triad of MEMs accelerometers. The remote datalogger and transceiver and accelerometer package measured 12 mm by 24 mm by 6 mm thick; these were mounted to the feet of thoroughbred horses to study their impact levels. These small, fast, wireless data recording systems can be used to monitor rotating/ vibrating machinery and civil/automotive/aerospace structures.
Building a Data Store with the Dynamic Structure
Directory of Open Access Journals (Sweden)
Yu. N. Artamonov
2016-01-01
Full Text Available This article presents the analysis of approaches to data warehouse construction based on relational and NoSQL solutions and lists the limitations of the relational approach to data mining. The contradiction between data presentation in the real subject domain and the model of data presentation in the relational and NoSQL approaches is revealed. The revealed contradiction is related to the temporality of the values of individual data attributes, the variability of the composition of these attributes, and structure of connections between them. A new logical model of the data warehouse with dynamic structure is proposed. The model is based on the concept of the object as a container for properties storage. Each property of the object includes the property name and two property values without reference and with reference, that are relevant at a given time. The reference property value points to an object whose name is interpreted as the value of the property at a given time. A formal description of the model with allocation of the necessary functionality to manipulate objects and their properties (selectors, predicates, constructors is given and the necessary control structures are introduced. Substantiation of the proposed model, called an OP-model is given on the basis of compliance with the logical ER data model. It is proved that any ER data model can be implemented in the OP-model. At the same time, the advantages of the OP-model are indicated, they are associated with the possibility of changing connections between entities due to changes in the reference value at a particular time. The potential for scalability of data warehouse due to the unique identification of each object is noted.
Lagged and instantaneous dynamical influences related to brain structural connectivity
Directory of Open Access Journals (Sweden)
Carmen eAlonso Montes
2015-07-01
Full Text Available Contemporary neuroimaging methods can shed light on the basis of human neural and cognitive specializations, with important implications for neuroscience and medicine. Indeed, different MRI acquisitions provide different brain networks at the macroscale; whilst diffusion-weighted MRI (dMRI provides a structural connectivity (SC coincident with the bundles of parallel fibers between brain areas, functional MRI (fMRI accounts for the variations in the blood-oxygenation-level-dependent T2* signal, providing functional connectivity (FC. Understanding the precise relation between FC and SC, that is, between brain dynamics and structure, is still a challenge for neuroscience.To investigate this problem, we acquired data at rest and built the corresponding SC (with matrix elements corresponding to the fiber number between brain areas to be compared with FC connectivity matrices obtained by three different methods: directed dependencies by an exploratory version of structural equation modeling (eSEM, linear correlations (C and partial correlations (PC. We also considered the possibility of using lagged correlations in time series; in particular, we compared a lagged version of eSEM and Granger causality (GC. Our results were two-fold: firstly, eSEM performance in correlating with SC was comparable to those obtained from C and PC, but eSEM (not C, nor PC provides information about directionality of the functional interactions. Second, interactions on a time scale much smaller than the sampling time, captured by instantaneous connectivity methods, are much more related to SC than slow directed influences captured by the lagged analysis. Indeed the performance in correlating with SC was much worse for GC and for the lagged version of eSEM. We expect these results to supply further insights to the interplay between SC and functional patterns, an important issue in the study of brain physiology and function.
Predicting Reactive Transport Dynamics in Carbonates using Initial Pore Structure
Menke, H. P.; Nunes, J. P. P.; Blunt, M. J.
2017-12-01
Understanding rock-fluid interaction at the pore-scale is imperative for accurate predictive modelling of carbon storage permanence. However, coupled reactive transport models are computationally expensive, requiring either a sacrifice of resolution or high performance computing to solve relatively simple geometries. Many recent studies indicate that initial pore structure many be the dominant mechanism in determining the dissolution regime. Here we investigate how well the initial pore structure is predictive of distribution and amount of dissolution during reactive flow using particle tracking on the initial image. Two samples of carbonate rock with varying initial pore space heterogeneity were reacted with reservoir condition CO2-saturated brine and scanned dynamically during reactive flow at a 4-μm resolution between 4 and 40 times using 4D X-ray micro-tomography over the course of 1.5 hours using μ-CT. Flow was modelled on the initial binarized image using a Navier-Stokes solver. Particle tracking was then run on the velocity fields, the streamlines were traced, and the streamline density was calculated both on a voxel-by-voxel and a channel-by-channel basis. The density of streamlines was then compared to the amount of dissolution in subsequent time steps during reaction. It was found that for the flow and transport regimes studied, the streamline density distribution in the initial image accurately predicted the dominant pathways of dissolution and gave good indicators of the type of dissolution regime that would later develop. This work suggests that the eventual reaction-induced changes in pore structure are deterministic rather than stochastic and can be predicted with high resolution imaging of unreacted rock.
Dynamics and management of stage-structured fish stocks.
Meng, Xinzhu; Lundström, Niklas L P; Bodin, Mats; Brännström, Åke
2013-01-01
With increasing fishing pressures having brought several stocks to the brink of collapse, there is a need for developing efficient harvesting methods that account for factors beyond merely yield or profit. We consider the dynamics and management of a stage-structured fish stock. Our work is based on a consumer-resource model which De Roos et al. (in Theor. Popul. Biol. 73, 47-62, 2008) have derived as an approximation of a physiologically-structured counterpart. First, we rigorously prove the existence of steady states in both models, that the models share the same steady states, and that there exists at most one positive steady state. Furthermore, we carry out numerical investigations which suggest that a steady state is globally stable if it is locally stable. Second, we consider multiobjective harvesting strategies which account for yield, profit, and the recovery potential of the fish stock. The recovery potential is a measure of how quickly a fish stock can recover from a major disturbance and serves as an indication of the extinction risk associated with a harvesting strategy. Our analysis reveals that a small reduction in yield or profit allows for a disproportional increase in recovery potential. We also show that there exists a harvesting strategy with yield close to the maximum sustainable yield (MSY) and profit close to that associated with the maximum economic yield (MEY). In offering a good compromise between MSY and MEY, we believe that this harvesting strategy is preferable in most instances. Third, we consider the impact of harvesting on population size structure and analytically determine the most and least harmful harvesting strategies. We conclude that the most harmful harvesting strategy consists of harvesting both adults and juveniles, while harvesting only adults is the least harmful strategy. Finally, we find that a high percentage of juvenile biomass indicates elevated extinction risk and might therefore serve as an early-warning signal of
Chiral dynamics and partonic structure at large transverse distances
Energy Technology Data Exchange (ETDEWEB)
Strikman, M. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Physics; Weiss, C. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States). Theory Center
2009-12-30
In this paper, we study large-distance contributions to the nucleon’s parton densities in the transverse coordinate (impact parameter) representation based on generalized parton distributions (GPDs). Chiral dynamics generates a distinct component of the partonic structure, located at momentum fractions x≲M_{π}/M_{N} and transverse distances b~1/M_{π}. We calculate this component using phenomenological pion exchange with a physical lower limit in b (the transverse “core” radius estimated from the nucleon’s axial form factor, R_{core}=0.55 fm) and demonstrate its universal character. This formulation preserves the basic picture of the “pion cloud” model of the nucleon’s sea quark distributions, while restricting its application to the region actually governed by chiral dynamics. It is found that (a) the large-distance component accounts for only ~1/3 of the measured antiquark flavor asymmetry d¯-u¯ at x~0.1; (b) the strange sea quarks s and s¯ are significantly more localized than the light antiquark sea; (c) the nucleon’s singlet quark size for x<0.1 is larger than its gluonic size, (b^{2})_{q+q¯}>(b^{2})_{g}, as suggested by the t-slopes of deeply-virtual Compton scattering and exclusive J/ψ production measured at HERA and FNAL. We show that our approach reproduces the general N_{c}-scaling of parton densities in QCD, thanks to the degeneracy of N and Δ intermediate states in the large-N_{c} limit. Finally, we also comment on the role of pionic configurations at large longitudinal distances and the limits of their applicability at small x.
Anawar, Hossain M; Rengel, Zed; Damon, Paul; Tibbett, Mark
2018-02-01
High arsenic (As) concentrations in the soil, water and plant systems can pose a direct health risk to humans and ecosystems. Phosphate (Pi) ions strongly influence As availability in soil, its uptake and toxicity to plants. Better understanding of As(V)-Pi interactions in soils and plants will facilitate a potential remediation strategy for As contaminated soils, reducing As uptake by crop plants and toxicity to human populations via manipulation of soil Pi content. However, the As(V)-Pi interactions in soil-plant systems are complex, leading to contradictory findings among different studies. Therefore, this review investigates the role of soil type, soil properties, minerals, Pi levels in soil and plant, Pi transporters, mycorrhizal association and microbial activities on As-Pi interactions in soils and hydroponics, and uptake by plants, elucidate the key mechanisms, identify key knowledge gaps and recommend new research directions. Although Pi suppresses As uptake by plants in hydroponic systems, in soils it could either increase or decrease As availability and toxicity to plants depending on the soil types, properties and charge characteristics. In soil, As(V) availability is typically increased by the addition of Pi. At the root surface, the Pi transport system has high affinity for Pi over As(V). However, Pi concentration in plant influences the As transport from roots to shoots. Mycorrhizal association may reduce As uptake via a physiological shift to the mycorrhizal uptake pathway, which has a greater affinity for Pi over As(V) than the root epidermal uptake pathway. Copyright © 2017 Elsevier Ltd. All rights reserved.
Structural Dynamic Analyses And Test Predictions For Spacecraft Structures With Non-Linearities
Vergniaud, Jean-Baptiste; Soula, Laurent; Newerla, Alfred
2012-07-01
The overall objective of the mechanical development and verification process is to ensure that the spacecraft structure is able to sustain the mechanical environments encountered during launch. In general the spacecraft structures are a-priori assumed to behave linear, i.e. the responses to a static load or dynamic excitation, respectively, will increase or decrease proportionally to the amplitude of the load or excitation induced. However, past experiences have shown that various non-linearities might exist in spacecraft structures and the consequences of their dynamic effects can significantly affect the development and verification process. Current processes are mainly adapted to linear spacecraft structure behaviour. No clear rules exist for dealing with major structure non-linearities. They are handled outside the process by individual analysis and margin policy, and analyses after tests to justify the CLA coverage. Non-linearities can primarily affect the current spacecraft development and verification process on two aspects. Prediction of flights loads by launcher/satellite coupled loads analyses (CLA): only linear satellite models are delivered for performing CLA and no well-established rules exist how to properly linearize a model when non- linearities are present. The potential impact of the linearization on the results of the CLA has not yet been properly analyzed. There are thus difficulties to assess that CLA results will cover actual flight levels. Management of satellite verification tests: the CLA results generated with a linear satellite FEM are assumed flight representative. If the internal non- linearities are present in the tested satellite then there might be difficulties to determine which input level must be passed to cover satellite internal loads. The non-linear behaviour can also disturb the shaker control, putting the satellite at risk by potentially imposing too high levels. This paper presents the results of a test campaign performed in
Directory of Open Access Journals (Sweden)
BERNARD DEMANZE eLaurence
2014-01-01
Full Text Available Posture control is based on central integration of multisensory inputs, and on internal representation of body orientation in space. This multisensory feedback regulates posture control and continuously updates the internal model of body’s position which in turn forwards motor commands adapted to the environmental context and constraints. The peripheral localization of the vestibular system, close to the cochlea, makes vestibular damage possible following cochlear implant (CI surgery. Impaired vestibular function in CI patients, if any, may have a strong impact on posture stability. The simple postural task of quiet standing is generally paired with cognitive activity in most day life conditions, leading therefore to competition for attentional resources in dual-tasking, and increased risk of fall particularly in patients with impaired vestibular function. This study was aimed at evaluating the effects of post-lingual cochlear implantation on posture control in adult deaf patients. Possible impairment of vestibular function was assessed by comparing the postural performance of patients to that of age-matched healthy subjects during a simple postural task performed in static and dynamic conditions, and during dual-tasking with a visual or auditory memory task. Postural tests were done in eyes open (EO and eyes closed (EC conditions, with the cochlear implant activated (ON or not (OFF. Results showed that the CI patients significantly reduced limits of stability and increased postural instability in static conditions. In dynamic conditions, they spent considerably more energy to maintain equilibrium, and their head was stabilized neither in space nor on trunk while the controls showed a whole body rigidification strategy. Hearing (prosthesis on as well as dual-tasking did not really improve the dynamic postural performance of the CI patients. We conclude that CI patients become strongly visual dependent mainly in challenging postural conditions.
Bernard-Demanze, Laurence; Léonard, Jacques; Dumitrescu, Michel; Meller, Renaud; Magnan, Jacques; Lacour, Michel
2013-01-01
Posture control is based on central integration of multisensory inputs, and on internal representation of body orientation in space. This multisensory feedback regulates posture control and continuously updates the internal model of body's position which in turn forwards motor commands adapted to the environmental context and constraints. The peripheral localization of the vestibular system, close to the cochlea, makes vestibular damage possible following cochlear implant (CI) surgery. Impaired vestibular function in CI patients, if any, may have a strong impact on posture stability. The simple postural task of quiet standing is generally paired with cognitive activity in most day life conditions, leading therefore to competition for attentional resources in dual-tasking, and increased risk of fall particularly in patients with impaired vestibular function. This study was aimed at evaluating the effects of postlingual cochlear implantation on posture control in adult deaf patients. Possible impairment of vestibular function was assessed by comparing the postural performance of patients to that of age-matched healthy subjects during a simple postural task performed in static (stable platform) and dynamic (platform in translation) conditions, and during dual-tasking with a visual or auditory memory task. Postural tests were done in eyes open (EO) and eyes closed (EC) conditions, with the CI activated (ON) or not (OFF). Results showed that the postural performance of the CI patients strongly differed from the controls, mainly in the EC condition. The CI patients showed significantly reduced limits of stability and increased postural instability in static conditions. In dynamic conditions, they spent considerably more energy to maintain equilibrium, and their head was stabilized neither in space nor on trunk: they behaved dynamically without vision like an inverted pendulum while the controls showed a whole body rigidification strategy. Hearing (prosthesis on) as well
Plasmodium vivax Population Structure and Transmission Dynamics in Sabah Malaysia
Abdullah, Noor Rain; Barber, Bridget E.; William, Timothy; Norahmad, Nor Azrina; Satsu, Umi Rubiah; Muniandy, Prem Kumar; Ismail, Zakiah; Grigg, Matthew J.; Jelip, Jenarun; Piera, Kim; von Seidlein, Lorenz; Yeo, Tsin W.; Anstey, Nicholas M.; Price, Ric N.; Auburn, Sarah
2013-01-01
Despite significant progress in the control of malaria in Malaysia, the complex transmission dynamics of P. vivax continue to challenge national efforts to achieve elimination. To assess the impact of ongoing interventions on P. vivax transmission dynamics in Sabah, we genotyped 9 short tandem repeat markers in a total of 97 isolates (8 recurrences) from across Sabah, with a focus on two districts, Kota Marudu (KM, n = 24) and Kota Kinabalu (KK, n = 21), over a 2 year period. STRUCTURE analysis on the Sabah-wide dataset demonstrated multiple sub-populations. Significant differentiation (F ST = 0.243) was observed between KM and KK, located just 130 Km apart. Consistent with low endemic transmission, infection complexity was modest in both KM (mean MOI = 1.38) and KK (mean MOI = 1.19). However, population diversity remained moderate (H E = 0.583 in KM and H E = 0.667 in KK). Temporal trends revealed clonal expansions reflecting epidemic transmission dynamics. The haplotypes of these isolates declined in frequency over time, but persisted at low frequency throughout the study duration. A diverse array of low frequency isolates were detected in both KM and KK, some likely reflecting remnants of previous expansions. In accordance with clonal expansions, high levels of Linkage Disequilibrium (I A S >0.5 [P<0.0001] in KK and KM) declined sharply when identical haplotypes were represented once (I A S = 0.07 [P = 0.0076] in KM, and I A S = -0.003 [P = 0.606] in KK). All 8 recurrences, likely to be relapses, were homologous to the prior infection. These recurrences may promote the persistence of parasite lineages, sustaining local diversity. In summary, Sabah's shrinking P. vivax population appears to have rendered this low endemic setting vulnerable to epidemic expansions. Migration may play an important role in the introduction of new parasite strains leading to epidemic expansions, with important implications for malaria
Dynamics of vortex structures in a stratified rotating fluid
Sokolovskiy, Mikhail A
2013-01-01
This book presents an extensive analysis of the dynamics of discrete and distributed baroclinic vortices in a multi-layer fluid that characterizes the main features of the large and mesoscales dynamics of the atmosphere and the ocean.
Ji, Pengfei; Zhang, Yuwen; Yang, Mo
2016-01-01
The structural, dynamic, and vibrational properties during the heat transfer process in Si/Ge superlattices, are studied by analyzing the trajectories generated by the ab initio Car-Parrinello molecular dynamics simulation. The radial distribution functions and mean square displacements are calculated and further discussions are made to explain and probe the structural changes relating to the heat transfer phenomenon. Furthermore, the vibrational density of states of the two layers (Si/Ge) ar...
Dynamic analysis of an industrial structure with fluid-structure interaction
International Nuclear Information System (INIS)
Sigrist, J.F.
2006-01-01
The present paper deals with the dynamic analysis of a nuclear reactor subjected to a shock loading with fluid-structure interaction modeling. The general framework of the study is that of linear vibrations, which are investigated for coupled fluid-structure problems. From a methodological point of view, energy deformation and modal mass calculation are exposed for elasto-acoustic systems. From an industrial point of view, the influence of elasto-acoustic coupling effects are highlighted for the studied structure. The dynamic analysis of the coupled system is carried out with various procedures (static, spectral and temporal methods), which are exposed and compared. As a general result, the spectral method is proved to be the most effective for the industrial problem. From the numerical point of view, the discretization procedure is based on a finite element method for the coupled problem, using a displacement and pressure-displacement potential coupled formulation with axi-symmetric representation of the problem unknowns. A finite element code is developed within MATLAB for the specific study, the numerical calculations presented in the paper are used as reference test cases for integration of the (u,p,φ) formulation in the commercial finite element code Ansys. (author)