Nonlinear dynamics of self-oscillating polymer gels
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
Self-oscillating polymer gels driven by Belousov-Zhabotinsky (BZ) chemical reaction are a new class of functional gels that have a wide range of potential applications (e.g., autonomously functioning membranes, actuate artificial muscles). However, the precise control of these gels has been an issue due to limited investigations of the influences of key system parameters on the characteristics of BZ gels. To address this deficiency, we studied the self-oscillating behavior of BZ gels using the nonline-ar dynamics theory and an Oregonator-like model, with focus placed upon the influences of various system parameters. The analysis of the oscillation phase indicated that the dynamic response of BZ gels represents the classical limit cycle oscillation. We then investigated the characteristics of the limit cycle oscillation and quantified the influences of key parameters (i.e., ini-tial reactant concentration, oxidation and reduction rate of catalyst, and response coefficient) on the self-oscillating behavior of BZ gels. The results demonstrated that sustained limit cycle oscillation of BZ gels can be achieved only when these key pa-rameters meet certain requirements, and that the pattern, period and amplitude of the oscillation are significantly influenced by these parameters. The results obtained in this study could enable the controlled self-oscillation of BZ gels system. This has several potential applications such as controlled drug delivery, miniature peristaltic pumps and microactuators.
DEFF Research Database (Denmark)
Isaeva, Olga B.; Kuznetsov, Sergey P.; Mosekilde, Erik
2011-01-01
The paper proposes an approach to constructing feasible examples of dynamical systems with hyperbolic chaotic attractors based on the successive transfer of excitation between two pairs of self-oscillators that are alternately active. An angular variable that measures the relations of the current...
Jenkins, Alejandro
2013-04-01
Physicists are very familiar with forced and parametric resonance, but usually not with self-oscillation, a property of certain dynamical systems that gives rise to a great variety of vibrations, both useful and destructive. In a self-oscillator, the driving force is controlled by the oscillation itself so that it acts in phase with the velocity, causing a negative damping that feeds energy into the vibration: no external rate needs to be adjusted to the resonant frequency. The famous collapse of the Tacoma Narrows bridge in 1940, often attributed by introductory physics texts to forced resonance, was actually a self-oscillation, as was the swaying of the London Millennium Footbridge in 2000. Clocks are self-oscillators, as are bowed and wind musical instruments. The heart is a “relaxation oscillator”, i.e., a non-sinusoidal self-oscillator whose period is determined by sudden, nonlinear switching at thresholds. We review the general criterion that determines whether a linear system can self-oscillate. We then describe the limiting cycles of the simplest nonlinear self-oscillators, as well as the ability of two or more coupled self-oscillators to become spontaneously synchronized (“entrained”). We characterize the operation of motors as self-oscillation and prove a theorem about their limit efficiency, of which Carnot’s theorem for heat engines appears as a special case. We briefly discuss how self-oscillation applies to servomechanisms, Cepheid variable stars, lasers, and the macroeconomic business cycle, among other applications. Our emphasis throughout is on the energetics of self-oscillation, often neglected by the literature on nonlinear dynamical systems.
Dynamics of self-oscillating cilia designed from active polymer gels
Dayal, Pratyush; Bhattacharya, Amitabh; Kuksenok, Olga; Balazs, Anna C.
2012-02-01
Using theory and simulations, we design active synthetic surfaces which are capable of replicating functionalities of biological cilia. In order to design such exquisite biomimetic systems we harness unique properties of polymer gels that undergo photosensitive Belousov-Zhabotinsky (BZ) reaction. Powered by internalized BZ reaction these polymer gels swell and de-swell autonomously by chemo-mechanical transduction and therefore are ideal materials for designing our system. In order to simulate the dynamics of the BZ cilia in surrounding fluid we have developed a nonlinear hybrid 3D model which captures elasto-dynamics of polymer gel and diffusive exchange of BZ reagents between the gel and the fluid. Here we show that the geometrical arrangement of cilia and the distribution of BZ activator in the fluid determine the dynamic response of the cilia. We further show that using light as an external stimulus we can sequentially modulate height of individual cilium and thereby create the ``piano effect''. Finally, we demonstrate that synchronized oscillations in the cilia result from the distribution of BZ-activator in the surrounding fluid. Our findings can be used to design active surfaces which can be remotely tuned depending upon the magnitude of external stimuli.
Self-oscillations in dynamic systems a new methodology via two-relay controllers
Aguilar, Luis T; Fridman, Leonid; Iriarte, Rafael
2015-01-01
This monograph presents a simple and efficient two-relay control algorithm for generation of self-excited oscillations of a desired amplitude and frequency in dynamic systems. Developed by the authors, the two-relay controller consists of two relays switched by the feedback received from a linear or nonlinear system, and represents a new approach to the self-generation of periodic motions in underactuated mechanical systems. The first part of the book explains the design procedures for two-relay control using three different methodologies – the describing-function method, Poincaré maps, and the locus-of-a perturbed-relay-system method – and concludes with stability analysis of designed periodic oscillations. Two methods to ensure the robustness of two-relay control algorithms are explored in the second part, one based on the combination of the high-order sliding mode controller and backstepping, and the other on higher-order sliding-modes-based reconstruction of uncertainties and their compensation where...
Jenkins, Alejandro
2011-01-01
Physicists are very familiar with forced and parametric resonance, but usually not with self-oscillation, a property of certain linear systems that gives rise to a great variety of vibrations, both useful and destructive. In a self-oscillator, the driving force is controlled by the oscillation itself so that it acts in phase with the velocity, causing a negative damping that feeds energy from the environment into the vibration: no external rate needs to be tuned to the resonant frequency. A paper from 1830 by G. B. Airy gives us the opening to introduce self-oscillation as a sort of "perpetual motion" responsible for the human voice. The famous collapse of the Tacoma Narrows bridge in 1940, often attributed by introductory physics texts to forced resonance, was actually a self-oscillation, as was the more recent swaying of the London Millenium Footbridge. Clocks are self-oscillators, as are bowed and wind musical instruments, and the heartbeat. We review the criterion that determines whether an arbitrary line...
Self oscillating PWM modulators, a topological comparison
DEFF Research Database (Denmark)
Poulsen, Søren; Andersen, Michael Andreas E.
2004-01-01
or fs/ð range respectively, where fs is the switching frequency of the converter. For some applications this will require unacceptable high switching frequency to achieve enough control loop bandwidth for the desired dynamic performance. With self oscillating modulators, the open loop bandwidth is equal...... to fs which makes this type of modulators an excellent choice for a wide range of applications. Self oscillating PWM modulators can be made in a number of ways, either as voltage or current mode modulators, and the self oscillating behavior can be achieved either by using hysteresis control......High precision control of the output voltage or current of a switch mode converter with fast response is required for a number of applications. Dependent on the type of application, the desired precision and transient response can be difficult, if not impossible, to achieve with standard PWM...
Frequency of self-oscillations
Groszkowski, Janusz
2013-01-01
Frequency of Self-Oscillations covers the realm of electric oscillations that plays an important role both in the scientific and technical aspects. This book is composed of nine chapters, and begins with the introduction to the alternating currents and oscillation. The succeeding chapters deal with the free oscillations in linear isolated systems. These topics are followed by discussions on self-oscillations in linear systems. Other chapters describe the self-oscillations in non-linear systems, the influence of linear elements on frequency of oscillations, and the electro mechanical oscillato
Strange nonchaotic self-oscillator
Jalnine, Alexey Yu.; Kuznetsov, Sergey P.
2016-08-01
An example of strange nonchaotic attractor (SNA) is discussed in a dissipative system of mechanical nature driven by a constant torque applied to one of the elements of the construction. So the external force is not oscillatory, and the system is autonomous. Components of the motion with incommensurable frequencies emerge due to the irrational ratio of the sizes of the involved rotating elements. We regard the phenomenon as strange nonchaotic self-oscillations, and its existence sheds new light on the question of feasibility of SNA in autonomous systems.
Digitized self-oscillating loop for piezoelectric transformer-based power converters
DEFF Research Database (Denmark)
Ekhtiari, Marzieh; Andersen, Thomas; Zhang, Zhe
2016-01-01
frequency control and ensures an optimum operation of the piezoelectric transformer in terms of voltage gain and efficiency. In this work, additional time delay is implemented digitally for the first time through 16 bit digital-to-analog converter to the self-oscillating loop. Delay control setpoints......A new method is implemented in designing of self-oscillating loop for driving piezoelectric transformers. The implemented method is based on combining both analog and digital control systems. Digitized delay, or digitized phase shift through the self-oscillating loop results in a very precise...... updates at a rate of 417 kHz. This allows the control loop to dynamically follow frequency changes of the transformer in each resonant cycle. The operation principle behind self-oscillating is discussed in this paper. Moreover, experimental results are reported....
Self-oscillating resonant power converter
DEFF Research Database (Denmark)
2014-01-01
The present invention relates to resonant power converters and inverters comprising a self-oscillating feedback loop coupled from a switch output to a control input of a switching network comprising one or more semiconductor switches. The self-oscillating feedback loop sets a switching frequency...... of the power converter and comprises a first intrinsic switch capacitance coupled between a switch output and a control input of the switching network and a first inductor. The first inductor is coupled in-between a first bias voltage source and the control input of the switching network and has...... a substantially fixed inductance. The first bias voltage source is configured to generate an adjustable bias voltage applied to the first inductor. The output voltage of the power converter is controlled in a flexible and rapid manner by controlling the adjustable bias voltage....
Turbulence and self-oscillations. [In magnetohydrodynamics
Energy Technology Data Exchange (ETDEWEB)
Bershadskii, A.G.
1985-12-01
The paper is concerned with the generation of turbulence by attenuating subcritical self-oscillations and with the evolution of this turbulence behind gratings, behind a cylinder, in ducts, and in a boundary layer (both in a magnetic field and in the absence of a magnetic field). Expressions are obtained for the spectral density of the energy, and the results are found to be in good agreement with experimental data. 15 references.
Direct and parametric synchronization of a graphene self-oscillator
Houri, S.; Cartamil-Bueno, S. J.; Poot, M.; Steeneken, P. G.; van der Zant, H. S. J.; Venstra, W. J.
2017-02-01
We explore the dynamics of a graphene nanomechanical oscillator coupled to a reference oscillator. Circular graphene drums are forced into self-oscillation, at a frequency f osc , by means of photothermal feedback induced by illuminating the drum with a continuous-wave red laser beam. Synchronization to a reference signal, at a frequency f sync , is achieved by shining a power-modulated blue laser onto the structure. We investigate two regimes of synchronization as a function of both detuning and signal strength for direct ( f sync ≈ f o s c ) and parametric locking ( f sync ≈ 2 f osc ) . We detect a regime of phase resonance, where the phase of the oscillator behaves as an underdamped second-order system, with the natural frequency of the phase resonance showing a clear power-law dependence on the locking signal strength. The phase resonance is qualitatively reproduced using a forced van der Pol-Duffing-Mathieu equation.
Sensitivity analysis of stochastically forced quasiperiodic self-oscillations
Directory of Open Access Journals (Sweden)
Irina Bashkirtseva
2016-08-01
Full Text Available We study a problem of stochastically forced quasi-periodic self-oscillations of nonlinear dynamic systems, which are modelled by an invariant torus in the phase space. For weak noise, an asymptotic of the stationary distribution of random trajectories is studied using the quasipotential. For the constructive analysis of a probabilistic distribution near a torus, we use a quadratic approximation of the quasipotential. A parametric description of this approximation is based on the stochastic sensitivity functions (SSF technique. Using this technique, we create a new mathematical method for the probabilistic analysis of stochastic flows near the torus. The construction of SSF is reduced to a boundary value problem for a linear differential matrix equation. For the case of the two-torus in the three-dimensional space, a constructive solution of this problem is given. Our theoretical results are illustrated with an example.
Investigation of Self-Oscillation using Particle Balance Model
Bae, Inshik; Na, Byungkeun; Chang, Hongyoung
2015-09-01
Self-oscillation, which is obtained by using a DC-only power supply with specific anode voltage conditions, is investigated in a cylindrical system with thermal electrons using tungsten filaments. From analysis of the obtained oscillation profiles, the experimental data is consistent with the model derived from the particle balance model. The self-oscillation period characteristics with respect to the pressure and gas species are also analyzed. As the physics and particle motion of self-oscillation near the electron avalanche is analyzed in different perspective, this study may advance the understanding of this phenomenon. This research was supported by the Ministry of Knowledge Economy (MKE) of Korea (Grant No. 10041681).
Self-oscillating loop based piezoelectric power converter
DEFF Research Database (Denmark)
2013-01-01
The present invention relates to a piezoelectric power converter comprising an input driver electrically coupled directly to an input or primary electrode of the piezoelectric transformer without any intervening series or parallel inductor. A feedback loop is operatively coupled between an output...... voltage of the piezoelectric transformer and the input driver to provide a self-oscillation loop around a primary section of the piezoelectric transformer oscillating at an excitation frequency. Electrical characteristics of the feedback loop are configured to set the excitation frequency of the self......- oscillation loop within a zero-voltage-switching (ZVS) operation range of the piezoelectric transformer....
Comparison of Simple Self-Oscillating PWM Modulators
DEFF Research Database (Denmark)
Dahl, Nicolai J.; Iversen, Niels Elkjær; Knott, Arnold
2016-01-01
Switch-mode power amplifiers has become the conventional choice for audio applications due to their superior efficiency and excellent audio performance. These amplifiers rely on high frequency modulation of the audio input. Conventional modulators use a fixed high frequency for modulation. Self......-oscillating modulators do not have a fixed modulation frequency and can provide good audio performance with very simple circuitry. This paper proposes a new type of self-oscillating modulator. The proposed modulator is compared to an already existing modulator of similar type and their performances are compared both...
Very High Frequency Interleaved Self-Oscillating Resonant SEPIC Converter
DEFF Research Database (Denmark)
Kovacevic, Milovan; Knott, Arnold; Andersen, Michael A. E.
2013-01-01
This paper describes analysis and design procedure of an interleaved, self-oscillating resonant SEPIC converter, suitable for operation at very high frequencies (VHF) ranging from 30 MHz to 300 MHz. The presented circuit consists of two resonant SEPIC DC-DC converters, and a capacitive...
Thermal self-oscillations in radiative heat exchange
Dyakov, S. A.; Dai, J.; Yan, M.; Qiu, M.
2015-02-01
We report the effect of relaxation-type self-induced temperature oscillations in the system of two parallel plates of SiO2 and VO2 which exchange heat by thermal radiation in vacuum. The non-linear feedback in the self-oscillating system is provided by metal-insulator transition in VO2. Using the method of fluctuational electrodynamics, we show that under the action of an external laser of a constant power, the temperature of VO2 plate oscillates around its phase transition value. The period and amplitude of oscillations depend on the geometry of the structure. We found that at 500 nm vacuum gap separating bulk SiO2 plate and 50 nm thick VO2 plate, the period of self-oscillations is 2 s and the amplitude is 4 K, which is determined by phase switching at threshold temperatures of phase transition.
Genuine Quantum Signatures in Synchronization of Anharmonic Self-Oscillators
Lörch, Niels; Amitai, Ehud; Nunnenkamp, Andreas; Bruder, Christoph
2016-08-01
We study the synchronization of a Van der Pol self-oscillator with Kerr anharmonicity to an external drive. We demonstrate that the anharmonic, discrete energy spectrum of the quantum oscillator leads to multiple resonances in both phase locking and frequency entrainment not present in the corresponding classical system. Strong driving close to these resonances leads to nonclassical steady-state Wigner distributions. Experimental realizations of these genuine quantum signatures can be implemented with current technology.
Self-oscillating loop based piezoelectric power converter
Rødgaard, Martin Schøler; Andersen, Michael A. E.; Esbern, Andreas; Meyer, Kasper Sinding
2013-01-01
The present invention relates to a piezoelectric power converter comprising an input driver electrically coupled directly to an input or primary electrode of the piezoelectric transformer without any intervening series or parallel inductor. A feedback loop is operatively coupled between an output voltage of the piezoelectric transformer and the input driver to provide a self-oscillation loop around a primary section of the piezoelectric transformer oscillating at an excitation frequency. Elec...
Self-oscillating AB diblock copolymer developed by post modification strategy
Energy Technology Data Exchange (ETDEWEB)
Ueki, Takeshi, E-mail: ueki@cross.t.u-tokyo.ac.jp, E-mail: ryo@cross.t.u-tokyo.ac.jp; Onoda, Michika; Tamate, Ryota; Yoshida, Ryo, E-mail: ueki@cross.t.u-tokyo.ac.jp, E-mail: ryo@cross.t.u-tokyo.ac.jp [Department of Materials Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Shibayama, Mitsuhiro [Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwano-ha, Kashiwa, Chiba 277-8581 (Japan)
2015-06-15
We prepared AB diblock copolymer composed of hydrophilic poly(ethylene oxide) segment and self-oscillating polymer segment. In the latter segment, ruthenium tris(2,2′-bipyridine) (Ru(bpy){sub 3}), a catalyst of the Belousov-Zhabotinsky reaction, is introduced into the polymer architecture based on N-isopropylacrylamide (NIPAAm). The Ru(bpy){sub 3} was introduced into the polymer segment by two methods; (i) direct random copolymerization (DP) of NIPAAm and Ru(bpy){sub 3} vinyl monomer and (ii) post modification (PM) of Ru(bpy){sub 3} with random copolymer of NIPAAm and N-3-aminopropylmethacrylamide. For both the diblock copolymers, a bistable temperature region (the temperature range; ΔT{sub m}), where the block copolymer self-assembles into micelle at reduced Ru(bpy){sub 3}{sup 2+} state whereas it breaks-up into individual polymer chain at oxidized Ru(bpy){sub 3}{sup 3+} state, monotonically extends as the composition of the Ru(bpy){sub 3} increases. The ΔT{sub m} of the block copolymer prepared by PM is larger than that by DP. The difference in ΔT{sub m} is rationalized from the statistical analysis of the arrangement of the Ru(bpy){sub 3} moiety along the self-oscillating segments. By using the PM method, the well-defined AB diblock copolymer having ΔT{sub m} (ca. 25 °C) large enough to cause stable self-oscillation can be prepared. The periodic structural transition of the diblock copolymer in a dilute solution ([Polymer] = 0.1 wt. %) is closely investigated in terms of the time-resolved dynamic light scattering technique at constant temperature in the bistable region. A macroscopic viscosity oscillation of a concentrated polymer solution (15 wt. %) coupled with the periodic microphase separation is also demonstrated.
Thermal self-oscillations in radiative heat exchange
Dyakov, Sergey; Yan, Min; Qiu, Min
2014-01-01
We report the effect of relaxation-type self-induced temperature oscillations in the system of two parallel plates of SiO$_2$ and VO$_2$ which exchange heat by thermal radiation in vacuum. The nonlinear feedback in the self-oscillating system is provided by metal-insulator transition in VO$_2$. Using the method of fluctuational electrodynamics we show that under the action of external laser of a constant power, the temperature of VO$_2$ plate oscillates around its phase transition value.
Minimizing Crosstalk in Self Oscillating Switch Mode Audio Power Amplifiers
DEFF Research Database (Denmark)
Knott, Arnold; Ploug, Rasmus Overgaard
2012-01-01
The varying switching frequencies of self oscillating switch mode audio amplifiers have been known to cause interchannel intermodulation disturbances in multi channel configurations. This crosstalk phenomenon has a negative impact on the audio performance. The goal of this paper is to present...... a method to minimize this phenomenon by improving the integrity of the various power distribution systems of the amplifier. The method is then applied to an amplifier built for this investigation. The results show that the crosstalk is suppressed with 30 dB, but is not entirely eliminated...
Analysis of friction self-oscillations of a drilling string with the exponential law of resistance
Energy Technology Data Exchange (ETDEWEB)
Belokobylskiy, S.V.; Prokopov, V.K.
1982-01-01
An analysis of the friction self-oscillations in the drilling string based on the exponential law of resistance with. A spasmodic law of resistance was obtained from it as a particular case. It is indicated that for definite parameters, the amplitude of self-oscillations with expoential law of resistance exceeds the scope of oscillations with spasmodic law. Dependences were constructed for the period of self-oscillations and time for motion from these parameters. Dangerous modes of friction self-oscillations were defined.
Interleaved Self-Oscillating Class E Derived Resonant DC/DC Converters
DEFF Research Database (Denmark)
Kovacevic, Milovan; Knott, Arnold; Andersen, Michael A. E.
2012-01-01
A new method for achieving self-oscillating, self-interleaved operation of class E derived resonant DC/DC converters is presented. The proposed method is suitable for operation at frequencies in the Very High Frequency (VHF) band. Interleaved and self-oscillating modes of operation are achieved...
Constant Switching Frequency Self-Oscillating Controlled Class-D Amplifiers
DEFF Research Database (Denmark)
Nguyen-Duy, Khiem; Knott, Arnold; Andersen, Michael A. E.
2014-01-01
The self-oscillating control approach has been used extensively in class-D amplifiers. It has several advantages such as high bandwidth and high audio performance. However, one of the primary disadvantages in a self-oscillating controlled system is that the switching frequency of the amplifier...
Investigation of crosstalk in self oscillating switch mode audio power amplifier
DEFF Research Database (Denmark)
Birch, Thomas Haagen; Ploug, Rasmus Overgaard; Iversen, Niels Elkjær
2012-01-01
channel self oscillating switch mode power amplier (class D). A step by step reduction of elements in an amplier built for this task, is used for methodically determining the actual presence and origins of crosstalk. The investigation shows that the crosstalk is caused by couplings in the self oscillating...
Molecular Design and Functional Control of Novel Self-Oscillating Polymers
Directory of Open Access Journals (Sweden)
Ryo Yoshida
2010-02-01
Full Text Available If we could realize an autonomous polymer system driven under biological conditions by a tailor-made molecular design, human beings could create unprecedented biomimetic functions and materials such as heartbeats, autonomous peristaltic pumps, etc. In order to achieve this objective, we have investigated the molecular design of such a polymer system. As a result, we were the first to demonstrate a self-oscillating polymer system driven in a solution where only malonic acid existed, which could convert the chemical energy of the Belousov-Zhabotinsky (BZ reaction into a change in the conformation of the polymer chain. To cause the self-oscillation in solution, we have attempted to construct a built-in system where the required BZ system substrates other than the organic acid are incorporated into the polymer itself. That is, the novel polymer chain incorporated the metal catalyst of the BZ reaction, a pH-control site and an oxidant supply site at the same time. As a result of introducing the pH control and oxidant supply sites into the conventional-type self-oscillating polymer chain, the novel polymer chain caused aggregation-disaggregation self-oscillations in the solution. We clarified that the period of the self-oscillation of the novel self-oscillating polymer chain was proportional to the concentration of the malonic acid. Therefore, the concentration of the malonic acid can be determined by measuring the period of the novel self-oscillating polymer solution. In this review, we introduce the detailed molecular design of the novel self-oscillating polymer chain and its self-oscillating behavior. Moreover, we report an autonomous self-oscillating polymer gel actuator that causes a bending-stretching motion under the constant conditions.
Control-volume representation of molecular dynamics.
Smith, E R; Heyes, D M; Dini, D; Zaki, T A
2012-05-01
A molecular dynamics (MD) parallel to the control volume (CV) formulation of fluid mechanics is developed by integrating the formulas of Irving and Kirkwood [J. Chem. Phys. 18, 817 (1950)] over a finite cubic volume of molecular dimensions. The Lagrangian molecular system is expressed in terms of an Eulerian CV, which yields an equivalent to Reynolds' transport theorem for the discrete system. This approach casts the dynamics of the molecular system into a form that can be readily compared to the continuum equations. The MD equations of motion are reinterpreted in terms of a Lagrangian-to-control-volume (LCV) conversion function ϑ(i) for each molecule i. The LCV function and its spatial derivatives are used to express fluxes and relevant forces across the control surfaces. The relationship between the local pressures computed using the volume average [Lutsko, J. Appl. Phys. 64, 1152 (1988)] techniques and the method of planes [Todd et al., Phys. Rev. E 52, 1627 (1995)] emerges naturally from the treatment. Numerical experiments using the MD CV method are reported for equilibrium and nonequilibrium (start-up Couette flow) model liquids, which demonstrate the advantages of the formulation. The CV formulation of the MD is shown to be exactly conservative and is, therefore, ideally suited to obtain macroscopic properties from a discrete system.
Multivariate volume visualization through dynamic projections
Energy Technology Data Exchange (ETDEWEB)
Liu, Shusen [Univ. of Utah, Salt Lake City, UT (United States); Wang, Bei [Univ. of Utah, Salt Lake City, UT (United States); Thiagarajan, Jayaraman J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Bremer, Peer -Timo [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Pascucci, Valerio [Univ. of Utah, Salt Lake City, UT (United States)
2014-11-01
We propose a multivariate volume visualization framework that tightly couples dynamic projections with a high-dimensional transfer function design for interactive volume visualization. We assume that the complex, high-dimensional data in the attribute space can be well-represented through a collection of low-dimensional linear subspaces, and embed the data points in a variety of 2D views created as projections onto these subspaces. Through dynamic projections, we present animated transitions between different views to help the user navigate and explore the attribute space for effective transfer function design. Our framework not only provides a more intuitive understanding of the attribute space but also allows the design of the transfer function under multiple dynamic views, which is more flexible than being restricted to a single static view of the data. For large volumetric datasets, we maintain interactivity during the transfer function design via intelligent sampling and scalable clustering. As a result, using examples in combustion and climate simulations, we demonstrate how our framework can be used to visualize interesting structures in the volumetric space.
High dynamic, low volume GPS receiver
Hurd, W. J.
1983-01-01
A new GPS receiver concept and design are presented to meet the high dynamic and low volume requirements for range applications in missiles and drones. The receiver has the potential to satisfy all range requirements with one basic receiver, which has significant potential economic benefit over the alternate approach of using a family of receivers, each tailored for specific applications. The main new concept is to use approximate maximum likelihood estimates of pseudo range and range-rate, rather than tracking with carrier phase locked loops and code delay locked loops. Preliminary analysis indicates that receivers accelerating at 50 g or more can track with position errors due to acceleration of approximately 0.2 m/g, or 10 m at 50 g. Implementation is almost entirely digital to meet the low volume requirements.
Ueki, Takeshi; Yoshida, Ryo
2014-06-14
Herein, we summarise the recent developments in self-oscillating polymeric materials based on the concepts of supramolecular chemistry, where aggregates of molecular building blocks with non-covalent bonds evolve the temporal or spatiotemporal structure. By utilising the rhythmic oscillation of the association/dissociation of molecular aggregates coupled with the redox oscillation by the BZ reaction, novel soft materials that express similar functions as those of living matter will be achieved. Further, from the viewpoint of materials science, our recent approach to prepare self-oscillating materials that operate long-term under mild conditions will be introduced.
Friction self-oscillation decrease in nonlinear system of locomotive traction drive
Antipin, D. Ya; Vorobiyov, V. I.; Izmerov, O. V.; Shorokhov, S. G.; Bondarenko, D. A.
2017-02-01
The problems of the friction self-oscillation decrease in a nonlinear system of a locomotive traction drive are considered. It is determined that the self-oscillation amplitude decrease in a locomotive wheel pair during boxing in traction drives with an elastic linkage between an armature of a traction electric motor and gearing can be achieved due to drive damping capacity during impact vibro-damping in an axle reduction gear with a hard driven gear. The self-oscillation amplitude reduction in a wheel pair in the designs of locomotive traction drives with the location of elastic elements between a wheel pair and gearing can be obtained owing to the application of drive inertial masses as an anti-vibrator. On the basis of the carried out investigations, a design variant of a self-oscillation shock absorber of a traction electric motor framework on a reduction gear suspension with an absorber located beyond a wheel-motor unit was offered.
Self-oscillating Vocal Fold Model Mechanics: Healthy, Diseased, and Aging
Hiubler, Elizabeth P.; Pollok, Lucas F. E.; Apostoli, Adam G.; Hancock, Adrienne B.; Plesniak, Michael W.
2014-11-01
Voice disorders have been estimated to have a substantial economic impact of 2.5 billion annually. Approximately 30% of people will suffer from a voice disorder at some point in their lives. Life-sized, self-oscillating, synthetic vocal fold (VF) models are fabricated to exhibit material properties representative of human VFs. These models are created both with and without a polyp-like structure, a pathology that has been shown to produce rich viscous flow structures not normally observed for healthy VFs during normal phonation. Pressure measurements are acquired upstream of the VFs and high-speed images are captured at varying flow rates during VF oscillation to facilitate an understanding of the characteristics of healthy and diseased VFs. The images are analyzed using a videokymography line-scan technique. Clinically-relevant parameters calculated from the volume-velocity output of a circumferentially-vented mask (Rothenberg mask) are compared to human data collected from two groups of males aged 18-30 and 60-80. This study extends the use of synthetic VF models by assessing their ability to replicate behaviors observed in human subject data to advance a means of investigating changes associated with normal, pathological, and the aging voice. Supported by the GWU Institute for Biomedical Engineering (GWIBE) and GWU Center for Biomimetics and Bioinspired Engineering (COBRE).
Flow past a self-oscillating airfoil with two degrees of freedom: measurements and simulations
Directory of Open Access Journals (Sweden)
Šidlof Petr
2014-03-01
Full Text Available The paper focuses on investigation of the unsteady subsonic airflow past an elastically supported airfoil for subcritical flow velocities and during the onset of the flutter instability. A physical model of the NACA0015 airfoil has been designed and manufactured, allowing motion with two degrees of freedom: pitching (rotation about the elastic axis and plunging (vertical motion. The structural mass and stiffness matrix can be tuned to certain extent, so that the natural frequencies of the two modes approach as needed. The model was placed in the measuring section of the wind tunnel in the aerodynamic laboratory of the Institute of Thermomechanics in Nový Knín, and subjected to low Mach number airflow up to the flow velocities when self-oscillation reach amplitudes dangerous for the structural integrity of the model. The motion of the airfoil was registered by a high-speed camera, with synchronous measurement of the mechanic vibration and discrete pressure sensors on the surface of the airfoil. The results of the measurements are presented together with numerical simulation results, based on a finite volume CFD model of airflow past a vibrating airfoil.
Multi-Volume High Resolution RGB-D Mapping with Dynamic Volume Placement
Salvato, Michael; Finman, Ross; Leonard, John
2015-01-01
We present a novel RGB-D mapping system for generating 3D maps over spatially extended regions with higher resolution than current methods using multiple, dynamically placed mapping volumes. Our method takes in RGB-D frames and dynamically assigns multiple mapping volumes to the environment, exchanging mapping volumes between the CPU and GPU. Mapping volumes are added or removed as needed to allow for spatially extended, high resolution mapping. Our system is designed to maximize the resoluti...
New Physics From A Dynamical Volume Element
Kaganovich, A B; Nissimov, E; Pacheva, S; Kaganovich, Alexander; Guendelman, Eduardo; Nissimov, Emil; Pacheva, Svetlana
2004-01-01
The use in the action integral of a volume element of the form $\\Phi d^{D}x$ where $\\Phi$ is a metric independent measure can give new interesting results in all types of known generally coordinate invariant theories: (1) 4-D theories of gravity plus matter fields; (2) Reparametrization invariant theories of extended objects; (3) Higher dimensional theories. In the case (1), a large number of new effects appears: under normal particle physics conditions (primordial) fermions split into three families; when matter is highly diluted, neutrinos increase their mass and can contribute both to dark energy and to dark matter. In the case (2), it leads to dynamically induced tension; to string models of non abelian confinement; to the possibility of new Weyl-conformally invariant light-like branes which dynamically adjust themselves to sit at black hole horizons; in the context of higher dimensional theories it can provide examples of massless 4-D particles with nontrivial Kaluza Klein quantum numbers. In the case (3...
Modeling mitochondrial bioenergetics with integrated volume dynamics.
Directory of Open Access Journals (Sweden)
Jason N Bazil
2010-01-01
Full Text Available Mathematical models of mitochondrial bioenergetics provide powerful analytical tools to help interpret experimental data and facilitate experimental design for elucidating the supporting biochemical and physical processes. As a next step towards constructing a complete physiologically faithful mitochondrial bioenergetics model, a mathematical model was developed targeting the cardiac mitochondrial bioenergetic based upon previous efforts, and corroborated using both transient and steady state data. The model consists of several modified rate functions of mitochondrial bioenergetics, integrated calcium dynamics and a detailed description of the K(+-cycle and its effect on mitochondrial bioenergetics and matrix volume regulation. Model simulations were used to fit 42 adjustable parameters to four independent experimental data sets consisting of 32 data curves. During the model development, a certain network topology had to be in place and some assumptions about uncertain or unobserved experimental factors and conditions were explicitly constrained in order to faithfully reproduce all the data sets. These realizations are discussed, and their necessity helps contribute to the collective understanding of the mitochondrial bioenergetics.
Modeling mitochondrial bioenergetics with integrated volume dynamics.
Bazil, Jason N; Buzzard, Gregery T; Rundell, Ann E
2010-01-01
Mathematical models of mitochondrial bioenergetics provide powerful analytical tools to help interpret experimental data and facilitate experimental design for elucidating the supporting biochemical and physical processes. As a next step towards constructing a complete physiologically faithful mitochondrial bioenergetics model, a mathematical model was developed targeting the cardiac mitochondrial bioenergetic based upon previous efforts, and corroborated using both transient and steady state data. The model consists of several modified rate functions of mitochondrial bioenergetics, integrated calcium dynamics and a detailed description of the K(+)-cycle and its effect on mitochondrial bioenergetics and matrix volume regulation. Model simulations were used to fit 42 adjustable parameters to four independent experimental data sets consisting of 32 data curves. During the model development, a certain network topology had to be in place and some assumptions about uncertain or unobserved experimental factors and conditions were explicitly constrained in order to faithfully reproduce all the data sets. These realizations are discussed, and their necessity helps contribute to the collective understanding of the mitochondrial bioenergetics.
Investigation of switching frequency variations in self-oscillating class D amplifiers
DEFF Research Database (Denmark)
Nielsen, Dennis; Knott, Arnold; Pfaffinger, Gerhard
2009-01-01
Class D audio amplifiers have gained significant influence in sound reproduction due to their high efficiency. One of the most commonly used control methods in class D amplifiers is known as self-oscillation. An parameter of key interest in self-oscillating class D amplifiers is the switching...... frequency, which can be directly related to the performance of the amplifier. This paper will clearify the myth of the switching frequency through investigation of its dependency on modulation index and reference frequency. Validation is done using simulations and an 50 W amplifier providing 0...
Instabilities in RF-power amplifiers caused by a self-oscillation in the transistor bias network
DEFF Research Database (Denmark)
Vidkjær, Jens
1976-01-01
This paper describes a self-oscillation in the bias network of an amplifier which is commonly used for the output stage in mobile transmitters. It is demonstrated how some often observed spurious oscillations may be related to the self-oscillation and a method for stabilizing the amplifier is der...
VHF Series-Input Parallel-Output Interleaved Self-Oscillating Resonant SEPIC Converter
DEFF Research Database (Denmark)
Kovacevic, Milovan; Knott, Arnold; Andersen, Michael A. E.
2013-01-01
If the switches of two resonant SEPIC converters are capacitively coupled, it is possible to obtain a self-oscillating converter in which the two power stages operate in interleaved mode. This paper describes a topology where the inputs of two SEPIC converters are connected in series, thereby sha...
Self-Oscillating Soft Switching Envelope Tracking Power Supply for Tetra2 Base Station
DEFF Research Database (Denmark)
Høyerby, Mikkel Christian Wendelboe; Andersen, Michael Andreas E.
2007-01-01
) implemented with a series inductor and an external clamping power supply. Combined with advanced power stage components (die-size MOSFETs), a high-performance fixed-frequency self-oscillating (sliding mode) control strategy and a 4th-order output filter, this leads to a compact, effective and efficient...
A VHF Class E DC-DC Converter with Self-Oscillating Gate Driver
DEFF Research Database (Denmark)
Andersen, Toke Meyer; Christensen, Søren K.; Knott, Arnold
2011-01-01
This paper describes the analysis and design of a DC-DC converter topology which is operational at frequencies in the Very High Frequency (VHF) band ranging from 30 MHz − 300 MHz. The presented topology, which consists of a class E inverter, class E rectifier, and self-oscillating gate driver, is...
Directory of Open Access Journals (Sweden)
Po Hu
2016-06-01
Full Text Available The synchronous tuning of the self-oscillating wireless power transfer (WPT in a close-coupling condition is studied in this paper. The Hamel locus is applied to predict the self-oscillating points in the WPT system. In order to make the system operate stably at the most efficient point, which is the middle resonant point when there are middle resonant and split frequency points caused by frequency-splitting, the receiver (RX rather than the transmitter (TX current is chosen as the self-oscillating feedback variable. The automatic delay compensation is put forward to eliminate the influence of the intrinsic delay on frequency tuning for changeable parameters. In addition, the automatic circuit parameter tuning based on the phase difference is proposed to realize the synchronous tuning of frequency and circuit parameters. The experiments verified that the synchronous tuning proposed in this paper is effective, fully automatic, and more robust than the previous self-oscillating WPT system which use the TX current as the feedback variable.
Locking of self-oscillation frequency by pump modulation in an erbium-doped fiber laser
Pisarchik, A. N.; Barmenkov, Yu. O.
2005-10-01
Frequency locking of self-oscillations in a diode-pumped erbium-doped fiber laser by external modulation of the diode current is studied experimentally. The coexistence of locking and unlocking regimes is detected. The condition for onset of the bistability and dependences of the frequency detuning on the modulation frequency and amplitude are established. Transitions to torus-chaos are also demonstrated.
Modeling Mitochondrial Bioenergetics with Integrated Volume Dynamics
Bazil, Jason N.; Buzzard, Gregery T.; Ann E Rundell
2010-01-01
Author Summary Mathematically modeling biological systems challenges our current understanding of the physical and biochemical events contributing to the observed dynamics. It requires careful consideration of hypothesized mechanisms, model development assumptions and details regarding the experimental conditions. We have adopted a modeling approach to translate these factors that explicitly considers the thermodynamic constraints, biochemical states and reaction mechanisms during model devel...
DEFF Research Database (Denmark)
Madsen, Mickey Pierre; Pedersen, Jeppe Arnsdorf; Knott, Arnold;
2014-01-01
This paper presents a new self-oscillating resonant gate drive composed solely of passive components. The gate drive can be used in various resonant converters and inverters and can be used for both low and high side gate drive. The paper presents examples of how higher order harmonics can be use...... Frequency (VHF) range, all showing good results with peak efficiency up to 82% and output regulation from 70% to full load without bursting....
Computational Methods in Stochastic Dynamics Volume 2
Stefanou, George; Papadopoulos, Vissarion
2013-01-01
The considerable influence of inherent uncertainties on structural behavior has led the engineering community to recognize the importance of a stochastic approach to structural problems. Issues related to uncertainty quantification and its influence on the reliability of the computational models are continuously gaining in significance. In particular, the problems of dynamic response analysis and reliability assessment of structures with uncertain system and excitation parameters have been the subject of continuous research over the last two decades as a result of the increasing availability of powerful computing resources and technology. This book is a follow up of a previous book with the same subject (ISBN 978-90-481-9986-0) and focuses on advanced computational methods and software tools which can highly assist in tackling complex problems in stochastic dynamic/seismic analysis and design of structures. The selected chapters are authored by some of the most active scholars in their respective areas and...
A modeling technique for STOVL ejector and volume dynamics
Drummond, C. K.; Barankiewicz, W. S.
1990-01-01
New models for thrust augmenting ejector performance prediction and feeder duct dynamic analysis are presented and applied to a proposed Short Take Off and Vertical Landing (STOVL) aircraft configuration. Central to the analysis is the nontraditional treatment of the time-dependent volume integrals in the otherwise conventional control-volume approach. In the case of the thrust augmenting ejector, the analysis required a new relationship for transfer of kinetic energy from the primary flow to the secondary flow. Extraction of the required empirical corrections from current steady-state experimental data is discussed; a possible approach for modeling insight through Computational Fluid Dynamics (CFD) is presented.
Saidi, Hiba; Erath, Byron D.
2015-11-01
The vocal folds play a major role in human communication by initiating voiced sound production. During voiced speech, the vocal folds are set into sustained vibrations. Synthetic self-oscillating vocal fold models are regularly employed to gain insight into flow-structure interactions governing the phonation process. Commonly, a fixed boundary condition is applied to the lateral, anterior, and posterior sides of the synthetic vocal fold models. However, physiological observations reveal the presence of adipose tissue on the lateral surface between the thyroid cartilage and the vocal folds. The goal of this study is to investigate the influence of including this substrate layer of adipose tissue on the dynamics of phonation. For a more realistic representation of the human vocal folds, synthetic multi-layer vocal fold models have been fabricated and tested while including a soft lateral layer representative of adipose tissue. Phonation parameters have been collected and are compared to those of the standard vocal fold models. Results show that vocal fold kinematics are affected by adding the adipose tissue layer as a new boundary condition.
Influence of nonlinearities on the power output of the Self-Oscillating Fluidic Heat Engine (SOFHE)
Tessier-Poirier, A.; Monin, T.; Léveillé, E.; Formosa, F.; Monfray, S.; Fréchette, L. G.
2016-11-01
In this paper, it is shown that two non-linearities drive the oscillations amplitude and the potential power density of the Self-Oscillating Fluidic Heat Engine (SOFHE). This new type of engine converts thermal energy into mechanical energy by producing self-sustained oscillations of a liquid column from a continuous heat source to power wireless sensors from waste heat. The underlying theoretical modeling shows that the pressure and the temperature nonlinearities limit the final oscillations amplitude, hence its achievable power density.
Self-oscillating modulators for direct energy conversion audio power amplifiers
Energy Technology Data Exchange (ETDEWEB)
Ljusev, P.; Andersen, Michael A.E.
2005-07-01
Direct energy conversion audio power amplifier represents total integration of switching-mode power supply and Class D audio power amplifier into one compact stage, achieving high efficiency, high level of integration, low component count and eventually low cost. This paper presents how self-oscillating modulators can be used with the direct switching-mode audio power amplifier to improve its performance by providing fast hysteretic control with high power supply rejection ratio, open-loop stability and high bandwidth. Its operation is thoroughly analyzed and simulated waveforms of a prototype amplifier are presented. (au)
Optomechanical self-oscillations in an anharmonic potential: engineering a nonclassical steady state
Grimm, Manuel; Bruder, Christoph; Lörch, Niels
2016-09-01
We study self-oscillations of an optomechanical system, where coherent mechanical oscillations are induced by a driven optical or microwave cavity, for the case of an anharmonic mechanical oscillator potential. A semiclassical analytical model is developed to characterize the limit cycle for large mechanical amplitudes corresponding to a weak nonlinearity. As a result, we predict conditions to achieve subpoissonian phonon statistics in the steady state, indicating classically forbidden behavior. We compare with numerical simulations and find very good agreement. Our model is quite general and can be applied to other physical systems such as trapped ions or superconducting circuits.
Self-oscillating modulators for direct energy conversion audio power amplifiers
Energy Technology Data Exchange (ETDEWEB)
Ljusev, P.; Andersen, Michael A.E.
2005-07-01
Direct energy conversion audio power amplifier represents total integration of switching-mode power supply and Class D audio power amplifier into one compact stage, achieving high efficiency, high level of integration, low component count and eventually low cost. This paper presents how self-oscillating modulators can be used with the direct switching-mode audio power amplifier to improve its performance by providing fast hysteretic control with high power supply rejection ratio, open-loop stability and high bandwidth. Its operation is thoroughly analyzed and simulated waveforms of a prototype amplifier are presented. (au)
Self-oscillating modulators for direct energy conversion audio power amplifiers
DEFF Research Database (Denmark)
Ljusev, Petar; Andersen, Michael Andreas E.
2005-01-01
Direct energy conversion audio power amplifier represents total integration of switching-mode power supply and Class D audio power amplifier into one compact stage, achieving high efficiency, high level of integration, low component count and eventually low cost. This paper presents how self......-oscillating modulators can be used with the direct switching-mode audio power amplifier to improve its performance by providing fast hysteretic control with high power supply rejection ratio, open-loop stability and high bandwidth. Its operation is thoroughly analyzed and experimental results from prototype amplifier...
Partial volume effects in dynamic contrast magnetic resonance renal studies
Energy Technology Data Exchange (ETDEWEB)
Gutierrez, D. Rodriguez, E-mail: drodriguez@biotronics3d.co [CVSSP, Faculty of Engineering and Physical Sciences, University of Surrey (United Kingdom); Wells, K., E-mail: k.wells@surrey.ac.u [CVSSP, Faculty of Engineering and Physical Sciences, University of Surrey (United Kingdom); Diaz Montesdeoca, O., E-mail: o.diaz.montesdeoca@gmail.co [EUITT, Universidad de Las Palmas de Gran Canaria (Spain); Moran Santana, A. [EUITT, Universidad de Las Palmas de Gran Canaria (Spain); Mendichovszky, I.A., E-mail: iosifm@hotmail.co [Radiology and Physics Unit, UCL Institute of Child Health, London WC1N 1EH (United Kingdom); Gordon, I., E-mail: i.gordon@ich.ucl.ac.u [Radiology and Physics Unit, UCL Institute of Child Health, London WC1N 1EH (United Kingdom)
2010-08-15
This is the first study of partial volume effect in quantifying renal function on dynamic contrast enhanced magnetic resonance imaging. Dynamic image data were acquired for a cohort of 10 healthy volunteers. Following respiratory motion correction, each voxel location was assigned a mixing vector representing the 'overspilling' contributions of each tissue due to the convolution action of the imaging system's point spread function. This was used to recover the true intensities associated with each constituent tissue. Thus, non-renal contributions from liver, spleen and other surrounding tissues could be eliminated from the observed time-intensity curves derived from a typical renal cortical region of interest. This analysis produced a change in the early slope of the renal curve, which subsequently resulted in an enhanced glomerular filtration rate estimate. This effect was consistently observed in a Rutland-Patlak analysis of the time-intensity data: the volunteer cohort produced a partial volume effect corrected mean enhancement of 36% in relative glomerular filtration rate with a mean improvement of 7% in r{sup 2} fitting of the Rutland-Patlak model compared to the same analysis undertaken without partial volume effect correction. This analysis strongly supports the notion that dynamic contrast enhanced magnetic resonance imaging of kidneys is substantially affected by the partial volume effect, and that this is a significant obfuscating factor in subsequent glomerular filtration rate estimation.
An introduction to finite volumes for gas dynamics
Dubois, François
2011-01-01
We propose an elementary introduction to the finite volume method in the context of gas dynamics conservation laws. Our approach is founded on the advection equation, the exact integration of the associated Cauchy problem, and the so-called upwind scheme in one space dimension. It is then extended in three directions: hyperbolic linear systems and particularily the system of acoustics, gas dynamics with the help of the Roe matrix and two space dimensions by following the approach proposed by Van Leer. A special emphasis on boundary conditions is proposed all along the text.
Forecasting of Machined Surface Waviness on the Basis of Self-oscillations Analysis
Belov, E. B.; Leonov, S. L.; Markov, A. M.; Sitnikov, A. A.; Khomenko, V. A.
2017-01-01
The paper states a problem of providing quality of geometrical characteristics of machined surfaces, which makes it necessary to forecast the occurrence and amount of oscillations appearing in the course of mechanical treatment. Objectives and tasks of the research are formulated. Sources of oscillation onset are defined: these are coordinate connections and nonlinear dependence of cutting force on the cutting velocity. A mathematical model of forecasting steady-state self-oscillations is investigated. The equation of the cutter tip motion is a system of two second-order nonlinear differential equations. The paper shows an algorithm describing a harmonic linearization method which allows for a significant reduction of the calculation time. In order to do that it is necessary to determine the amplitude of oscillations, frequency and a steady component of the first harmonic. Software which allows obtaining data on surface waviness parameters is described. The paper studies an example of the use of the developed model in semi-finished lathe machining of the shaft made from steel 40H which is a part of the BelAZ wheel electric actuator unit. Recommendations on eliminating self-oscillations in the process of shaft cutting and defect correction of the surface waviness are given.
A consensus-based dynamics for market volumes
Sabatelli, Lorenzo; Richmond, Peter
2004-12-01
We develop a model of trading orders based on opinion dynamics. The agents may be thought as the share holders of a major mutual fund rather than as direct traders. The balance between their buy and sell orders determines the size of the fund order (volume) and has an impact on prices and indexes. We assume agents interact simultaneously to each other through a Sznajd-like interaction. Their degree of connection is determined by the probability of changing opinion independently of what their neighbours are doing. We assume that such a probability may change randomly, after each transaction, of an amount proportional to the relative difference between the volatility then measured and a benchmark that we assume to be an exponential moving average of the past volume values. We show how this simple model is compatible with some of the main statistical features observed for the asset volumes in financial markets.
Dynamics at Solid State Surfaces and Interfaces Volume 2 Fundamentals
Bovensiepen, Uwe; Wolf, Martin
2012-01-01
This two-volume work covers ultrafast structural and electronic dynamics of elementary processes at solid surfaces and interfaces, presenting the current status of photoinduced processes. Providing valuable introductory information for newcomers to this booming field of research, it investigates concepts and experiments, femtosecond and attosecond time-resolved methods, as well as frequency domain techniques.The whole is rounded off by a look at future developments.
Cosmology via Metric-Independent Volume-Form Dynamics
Guendelman, Eduardo; Pacheva, Svetlana
2015-01-01
The method of non-Riemannian volume-forms (metric-independent covariant integration measure densities on the spacetime manifold) is applied to construct a unified model of dynamical dark energy plus dark matter as a dust fluid resulting from a hidden Noether symmetry of the pertinent scalar field Lagrangian. Canonical Hamiltonian treatment and Wheeler-DeWitt quantization of the latter model are briefly discussed.
Internet traffic load balancing using dynamic hashing with flow volume
Jo, Ju-Yeon; Kim, Yoohwan; Chao, H. Jonathan; Merat, Francis L.
2002-07-01
Sending IP packets over multiple parallel links is in extensive use in today's Internet and its use is growing due to its scalability, reliability and cost-effectiveness. To maximize the efficiency of parallel links, load balancing is necessary among the links, but it may cause the problem of packet reordering. Since packet reordering impairs TCP performance, it is important to reduce the amount of reordering. Hashing offers a simple solution to keep the packet order by sending a flow over a unique link, but static hashing does not guarantee an even distribution of the traffic amount among the links, which could lead to packet loss under heavy load. Dynamic hashing offers some degree of load balancing but suffers from load fluctuations and excessive packet reordering. To overcome these shortcomings, we have enhanced the dynamic hashing algorithm to utilize the flow volume information in order to reassign only the appropriate flows. This new method, called dynamic hashing with flow volume (DHFV), eliminates unnecessary flow reassignments of small flows and achieves load balancing very quickly without load fluctuation by accurately predicting the amount of transferred load between the links. In this paper we provide the general framework of DHFV and address the challenges in implementing DHFV. We then introduce two algorithms of DHFV with different flow selection strategies and show their performances through simulation.
Monin, T.; Tessier-Poirier, A.; Léveillé, E.; Juneau-Fecteau, A.; Skotnicki, T.; Formosa, F.; Monfray, S.; Fréchette, L. G.
2016-11-01
In this paper, we present the working principle and first experimental demonstration of an innovative approach to harvest low-quality heat sources, the Self-Oscillating Fluidic Heat Engine (SOFHE). Thermal energy is first converted into pressure pulsations by a selfexcited thermo-fluidic oscillator driven by periodic phase change of a fluid in an enclosed channel. A piezoelectric membrane then converts this mechanical energy into an electrical power. After describing the working principle, an experimental demonstration is presented. The P-V diagram of this new thermodynamic cycle is measured, showing a mechanical power of 3.3mW. Combined with a piezoelectric spiral membrane, the converted electrical power generation achieved is close to 1μ W in a 1MΩ load. This work sets the basis for future development of this new type of heat engine for waste heat recovery and to power wireless sensors.
High-endurance megahertz electrical self-oscillation in Ti/NbOx bilayer structures
Li, Shuai; Liu, Xinjun; Nandi, Sanjoy Kumar; Venkatachalam, Dinesh Kumar; Elliman, Robert Glen
2015-05-01
Electrical self-oscillation is reported for a Ti/NbOx negative differential resistance device incorporated in a simple electric circuit configuration. Measurements confirm stable operation of the oscillator at source voltages as low as 1.06 V, and demonstrate frequency control in the range from 2.5 to 20.5 MHz for voltage changes as small as ˜1 V. Device operation is reported for >6.5 × 1010 cycles, during which the operating frequency and peak-to-peak device current decreased by ˜25%. The low operating voltage, large frequency range, and high endurance of these devices makes them particularly interesting for applications such as neuromorphic computing.
Amoeba-like self-oscillating polymeric fluids with autonomous sol-gel transition
Onoda, Michika; Ueki, Takeshi; Tamate, Ryota; Shibayama, Mitsuhiro; Yoshida, Ryo
2017-07-01
In the field of polymer science, many kinds of polymeric material systems that show a sol-gel transition have been created. However, most systems are unidirectional stimuli-responsive systems that require physical signals such as a change in temperature. Here, we report on the design of a block copolymer solution that undergoes autonomous and periodic sol-gel transition under constant conditions without any on-off switching through external stimuli. The amplitude of this self-oscillation of the viscosity is about 2,000 mPa s. We also demonstrate an intermittent forward motion of a droplet of the polymer solution synchronized with the autonomous sol-gel transition. This polymer solution bears the potential to become the base for a type of slime-like soft robot that can transform its shape kaleidoscopically and move autonomously, which is associated with the living amoeba that moves forward by a repeated sol-gel transition.
Self-oscillation acoustic system destined to measurement of stresses in mass rocks
Kwasniewski, Janusz; Dominik, Ireneusz; Dorobczynski, Lech
2011-01-01
The paper presents an electronic self-oscillation acoustic system (SAS) destined to measure of stresses variations in the elastic media. The system consists of piezoelectric detector, amplifier-limiter, pass-band filter, piezoelectric exciter and the frequency meter. The mass rock plays a role of delaying element, in which variations in stresses causing the variations of acoustic wave velocity of propagation, and successive variation in frequency of oscillations generated by system. The laboratory test permitted to estimate variations in frequency caused by variations in stresses of elastic medium. The principles of selection of frequency and other parameters of the electronic system in application to stresses measurement in condition of the mine were presented.
Simulation of Vocal Folds: A Fluid-Induced Self-Oscillating Problem
Wang, Xingshi; Zhang, Lucy
2009-11-01
The goal of this study is to investigate the process of voice production by simulating the motion and deformation of human vocal folds. The vocal folds are oscillated by a constant lung pressure driven airflow in the throat. The system is modeled in 2-D using the immersed finite element method to simulate and study the fluid-structure interaction mechanism. From our numerical results, the glottal jets are identified. Several parameters such as the Reynolds number, Strouhal number, vocal folds stiffness, density ratio between the fluid and the structure are addressed and compared with experimental results. The frequency of the vocal folds vibration, fluid flow rate and pressure distribution are also investigated. In addition, the energy transfer between the fluid domain and the solid domain are analyzed to assist in explaining the underlying physical mechanism for this fluid-induced self-oscillating vocal folds.
Operation Performance of Self-Oscillation Ultrasonic Vibrating Device for Liquid Atomization
Toda, Kohji; Ishii, Jun
1995-09-01
An ultrasonic vibrating device, composed of a rectangular piezoelectric ceramic plate and a metal plate is described for liquid atomization. The resonance is used for the self-oscillation, which arises from the coupling between two vibration modes in the ceramic plate. The best operation occurs when one of the resonant frequencies of the vibrating device is equal to that of the piezoelectric ceramic plate without the metal plate. The ceramic plate has two electrodes on one of the two surfaces. A power feeding circuit is composed of the piezoelectric ceramic plate with three electrode terminals, which functions as a resonant element as well as a vibration source, and a power amplification transistor. The metal plate with minute holes functions effectively for liquid atomization.
DEFF Research Database (Denmark)
Nielsen, Dennis; Knott, Arnold; Andersen, Michael A. E.
2013-01-01
A hysteretic self-oscillating bandpass current mode control (BPCM) scheme for Class D audio amplifiers driving capacitive transducers are presented. The scheme provides excellent stability margins and low distortion over a wide range of operating conditions. Small-signal behavior of the amplifier...... the rules of electrostatics have been known as very interesting alternatives to the traditional inefficient electrodynamic transducers. When driving capacitive transducers from a Class D audio amplifier the high impedance nature of the load represents a key challenge. The BPCM control scheme ensures a flat...... is analysis through transfer function based linear control methodology. Measurements are performed on a single-ended ± 300 V half-bridge amplifier driving a capacitive load of 100 nF. Total Harmonic Distortion plus noise (THD+N) below 0.1 % are reported. Transducers representing a capacitive load and obeying...
Carrier Distortion in Hysteretic Self-Oscillating Class-D Audio Power
DEFF Research Database (Denmark)
Høyerby, Mikkel Christian Kofod; Andersen, Michael A. E.
2009-01-01
An important distortion mechanism in hysteretic self-oscillating (SO) class-D (switch mode) power amplifiers-–carrier distortion-–is analyzed and an optimization method is proposed. This mechanism is an issue in any power amplifier application where a high degree of proportionality between input...... and output is required, such as in audio power amplifiers or xDSL drivers. From an average-mode point of view, carrier distortion is shown to be caused by nonlinear variation of the hysteretic comparator input average voltage with the output average voltage. This easily causes total harmonic distortion...... proven in an audio power amplifier leading to THD figures that are comparable to the state of the art. Experimental hardware is a hysteretic SO bandpass current-mode-controlled single-ended audio power amplifier capable of 45 W into 8 Omega or 80 W into 4 Omega from a pm34 V supply with less than 0...
DYNAMIC TRAINING VOLUME: A CONSTRUCT OF BOTH TIME UNDER TENSION AND VOLUME LOAD
Directory of Open Access Journals (Sweden)
Quan T. Tran
2006-12-01
Full Text Available The purpose of this study was to investigate the effects of three different weight training protocols, that varied in the way training volume was measured, on acute muscular fatigue. Ten resistance-trained males performed all three protocols which involved dynamic constant resistance exercise of the elbow flexors. Protocol A provided a standard for the time the muscle group was under tension (TUT and volume load (VL, expressed as the product of the total number of repetitions and the load that was lifted. Protocol B involved 40% of the TUT but the same VL compared to protocol A; protocol C was equated with protocol A for TUT but only involved 50% of the VL. Fatigue was assessed by changes in maximum voluntary isometric force and integrated electromyography (iEMG between the pre- and post-training protocols. The results of the study showed that, when equated for VL, greater TUT produced greater overall muscular fatigue (p < 0.001 as reflected by the reduction in the force generating capability of the muscle. When the protocols were equated for TUT, greater VL (p < 0.01 resulted in greater overall muscular fatigue. All three protocols resulted in significant decreases in iEMG (p < 0.05 but they were not significantly different from each other. It was concluded that, because of the importance of training volume to neuromuscular adaptation, the training volume needs to be clearly described when designing resistance training programs
Price and Volume Dynamics in the Japanese Stock Market
Yamashita, Hirofumi; Takayasu, Hideki; Takayasu, Misako
We investigated data of stocks listed on Tokyo Stock Exchange. Although the data we used contains limited number of limit orders around the best prices in the ask and bid sides, we could confirm some issues of the layered structure which is similar to that in FX markets. We show time series of a market impact index, which is made using high correlation between dynamics of price and volume of limit orders. In the last section, we remark differences in our observations comparing with the FX market case.
Dynamical Volume Element in Scale-Invariant and Supergravity Theories
Guendelman, Eduardo; Pacheva, Svetlana; Vasihoun, Mahary
2013-01-01
The use in the action integral of a volume element of the form $\\Phi d^{D}x$, where $\\Phi$ is a metric-independent measure density, can yield new interesting results in all types of known generally coordinate-invariant theories: (1) 4-D theories of gravity plus matter fields; (2) reparametrization invariant theories of extended objects (strings and branes); (3) supergravity theories. In case (1) we obtain interesting insights concerning the cosmological constant problem, inflation and quintessence without the fifth force problem. In case (2) the above formalism leads to dynamically induced tension and to string models of non-abelian confinement. In case (3), we show that the modified-measure supergravity generates an arbitrary dynamically induced cosmological constant.
Dorozhkin, S. I.
2015-07-01
Self-oscillations of a microwave photovoltage with irregular interruptions have been discovered in the states with vanishing dc dissipation emerging in two-dimensional electron systems under microwave irradiation. The observed picture can be caused by transitions between a stable pole and a limiting cycle in the phase space of the systems (Andronov-Hopf bifurcation) that occur owing to fluctuations.
Dynamic Garment Simulation based on Hybrid Bounding Volume Hierarchy
Directory of Open Access Journals (Sweden)
Zhu Dongyong
2016-12-01
Full Text Available In order to solve the computing speed and efficiency problem of existing dynamic clothing simulation, this paper presents a dynamic garment simulation based on a hybrid bounding volume hierarchy. It firstly uses MCASG graph theory to do the primary segmentation for a given three-dimensional human body model. And then it applies K-means cluster to do the secondary segmentation to collect the human body’s upper arms, lower arms, upper legs, lower legs, trunk, hip and woman’s chest as the elementary units of dynamic clothing simulation. According to different shapes of these elementary units, it chooses the closest and most efficient hybrid bounding box to specify these units, such as cylinder bounding box and elliptic cylinder bounding box. During the process of constructing these bounding boxes, it uses the least squares method and slices of the human body to get the related parameters. This approach makes it possible to use the least amount of bounding boxes to create close collision detection regions for the appearance of the human body. A spring-mass model based on a triangular mesh of the clothing model is finally constructed for dynamic simulation. The simulation result shows the feasibility and superiority of the method described.
Effect of volume fraction on granular avalanche dynamics.
Gravish, Nick; Goldman, Daniel I
2014-09-01
We study the evolution and failure of a granular slope as a function of prepared volume fraction, ϕ(0). We rotated an initially horizontal layer of granular material (0.3-mm-diam glass spheres) to a 45° angle while we monitor the motion of grains from the side and top with high-speed video cameras. The dynamics of grain motion during the tilt process depended sensitively on ϕ(0)∈[0.58-0.63] and differed above or below the granular critical state, ϕ(c), defined as the onset of dilation as a function of increasing volume fraction. For ϕ(0)-ϕ(c)avalanche. Precursor compaction events began at an initial angle θ(0)=7.7±1.4° and occurred intermittently prior to the onset of an avalanche. Avalanches occurred at the maximal slope angle θ(m)=28.5±1.0°. Granular material at ϕ(0)-ϕ(c)>0 did not experience precursor compaction prior to avalanche flow, and instead experienced a single dilational motion at θ(0)=32.1±1.5° prior to the onset of an avalanche at θ(m)=35.9±0.7°. Both θ(0) and θ(m) increased with ϕ(0) and approached the same value in the limit of random close packing. The angle at which avalanching grains came to rest, θ(R)=22±2°, was independent of ϕ(0). From side-view high-speed video, we measured the velocity field of intermittent and avalanching flow. We found that flow direction, depth, and duration were affected by ϕ(0), with ϕ(0)-ϕ(c)0. Our study elucidates how initial conditions-including volume fraction-are important determinants of granular slope stability and the onset of avalanches.
Motion analysis of knee joint using dynamic volume images
Haneishi, Hideaki; Kohno, Takahiro; Suzuki, Masahiko; Moriya, Hideshige; Mori, Sin-ichiro; Endo, Masahiro
2006-03-01
Acquisition and analysis of three-dimensional movement of knee joint is desired in orthopedic surgery. We have developed two methods to obtain dynamic volume images of knee joint. One is a 2D/3D registration method combining a bi-plane dynamic X-ray fluoroscopy and a static three-dimensional CT, the other is a method using so-called 4D-CT that uses a cone-beam and a wide 2D detector. In this paper, we present two analyses of knee joint movement obtained by these methods: (1) transition of the nearest points between femur and tibia (2) principal component analysis (PCA) of six parameters representing the three dimensional movement of knee. As a preprocessing for the analysis, at first the femur and tibia regions are extracted from volume data at each time frame and then the registration of the tibia between different frames by an affine transformation consisting of rotation and translation are performed. The same transformation is applied femur as well. Using those image data, the movement of femur relative to tibia can be analyzed. Six movement parameters of femur consisting of three translation parameters and three rotation parameters are obtained from those images. In the analysis (1), axis of each bone is first found and then the flexion angle of the knee joint is calculated. For each flexion angle, the minimum distance between femur and tibia and the location giving the minimum distance are found in both lateral condyle and medial condyle. As a result, it was observed that the movement of lateral condyle is larger than medial condyle. In the analysis (2), it was found that the movement of the knee can be represented by the first three principal components with precision of 99.58% and those three components seem to strongly relate to three major movements of femur in the knee bend known in orthopedic surgery.
Yashin, Victor V; Levitan, Steven P; Balazs, Anna C
2015-06-24
Lightweight, deformable materials that can sense and respond to human touch and motion can be the basis of future wearable computers, where the material itself will be capable of performing computations. To facilitate the creation of "materials that compute", we draw from two emerging modalities for computation: chemical computing, which relies on reaction-diffusion mechanisms to perform operations, and oscillatory computing, which performs pattern recognition through synchronization of coupled oscillators. Chemical computing systems, however, suffer from the fact that the reacting species are coupled only locally; the coupling is limited by diffusion as the chemical waves propagate throughout the system. Additionally, oscillatory computing systems have not utilized a potentially wearable material. To address both these limitations, we develop the first model for coupling self-oscillating polymer gels to a piezoelectric (PZ) micro-electro-mechanical system (MEMS). The resulting transduction between chemo-mechanical and electrical energy creates signals that can be propagated quickly over long distances and thus, permits remote, non-diffusively coupled oscillators to communicate and synchronize. Moreover, the oscillators can be organized into arbitrary topologies because the electrical connections lift the limitations of diffusive coupling. Using our model, we predict the synchronization behavior that can be used for computational tasks, ultimately enabling "materials that compute".
Self-Oscillation-Based Frequency Tracking for the Drive and Detection of Resonance Magnetometers.
Tian, Zheng; Ren, Dahai; You, Zheng
2016-05-21
This paper reports a drive and detection method for Micro-Electro-Mechanical System (MEMS)-based Lorentz-force resonance magnetometers. Based on the proposed MEMS magnetometer, a drive and detection method was developed by using self-oscillation to adjust the mismatch between the mechanical resonance frequency and the coil drive frequency as affected by temperature fluctuations and vibration amplitude changes. Not only was the signal-to-noise ratio enhanced by the proposed method compared to the traditional method, but the test system automatically reached resonance frequency very rapidly when powered on. Moreover, the linearity and the measurement range were improved by the magnetic feedback generated by the coil. Test results indicated that the sensitivity of the proposed magnetometer is 59.6 mV/μT and its noise level is 0.25 μT. When operating in ±65 μT, its nonlinearity is 2.5‰-only one-tenth of the former prototype. Its power consumption is only about 250 mW and its size is only 28 mm × 28 mm × 10 mm, or about one-eighth of the original sensor; further, unlike the former device, it can distinguish both positive and negative magnetic fields. The proposed method can also be applied in other MEMS sensors such as gyroscopes and micromirrors to enhance their frequency tracking ability.
Balazs, Anna
Lightweight, deformable materials that can sense and respond to human touch and motion can be the basis of future wearable computers, where the material itself will be capable of performing computations. To facilitate the creation of ''materials that compute'', we draw from two emerging modalities for computation: chemical computing, which relies on reaction-diffusion mechanisms to perform operations, and oscillatory computing, which performs pattern recognition through synchronization of coupled oscillators. Chemical computing systems, however, suffer from the fact that the reacting species are coupled only locally; the coupling is limited by diffusion as the chemical waves propagate throughout the system. Additionally, oscillatory computing systems have not utilized a potentially wearable material. To address both these limitations, we develop the first model for coupling self-oscillating polymer gels to a piezoelectric (PZ) micro-electro-mechanical system (MEMS). The resulting transduction between chemo-mechanical and electrical energy creates signals that can be propagated quickly over long distances and thus, permits remote, non-diffusively coupled oscillators to communicate and synchronize. The oscillators can be organized into arbitrary topologies because the electrical connections lift the limitations of diffusive coupling. Using our model, we predict the synchronization behavior that can be used for computational tasks, ultimately enabling ''materials that compute''.
The Analysis and Design of a Dual-Band Self-Oscillating Mixer
Directory of Open Access Journals (Sweden)
Alishir Moradi Kordalivand
2011-06-01
Full Text Available Here, a self-oscillating mixer is experimentally demonstrated employing both the fundamental and harmonic signals generated by the oscillator sub-circuit in the mixing process. The resulting circuit is a dual-band down-converting mixer that can operate in the C-band, or in the X-band. The oscillator uses the active super harmonic coupling to enforce the quadrature relationship of the fundamental outputs. Either the fundamental outputs of the oscillator or the second harmonic oscillator output signals present at the common mode nodes are connected to the mixer via a set of complementary switches. The mixer achieves a conversion gain between 9–11.5 dB in both frequency bands. The third-order output intercept-point for the C-band and the X–band operations are 10.42 and 8.33 dBm, respectively. The circuit was designed and simulated in 0.18- CMOS technology by ADS2008.
Airflow visualization in a model of human glottis near the self-oscillating vocal folds model
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Horáček J.
2011-06-01
Full Text Available The contribution describes PIV (Particle Image Velocimetry measurement of airflow in the glottal region of complex physical models of the voice production that consist of 1 : 1 scaled models of the trachea, the self-oscillating vocal folds and the human vocal tract with acoustical spaces that correspond to the vowels /a:/, /u:/ and /i:/. The time-resolved PIV method was used for visualization of the airflow simultaneously with measurements of subglottal pressure, radiated acoustic pressure and vocal fold vibrations. The measurements were performed within a physiologically real range of mean airflow rate and fundamental phonation frequency. The images of the vibrating vocal folds during one oscillation period were recorded by the high-speed camera at the same time instants as the velocity fields measured by the PIV method.In the region above the models of the ventricular folds and of the epilaryngeal tube it is possible to detect large vortices with dimensions comparable with the channel cross-section and moving relatively slowly downstream. The vortices disappear in the narrower pharyngeal part of the vocal tract model where the flow is getting more uniform. The basic features of the coherent structures identified in the laryngeal cavity models in the interval of the measured airflow rates were found qualitatively similar for all three vowels investigated.
Energy Technology Data Exchange (ETDEWEB)
Artzi, Moran [Tel Aviv Sourasky Medical Center, Functional Brain Center, The Wohl Institute for Advanced Imaging, Tel Aviv (Israel); Tel Aviv University, Sackler Faculty of Medicine, Tel Aviv (Israel); Liberman, Gilad; Vitinshtein, Faina; Aizenstein, Orna [Tel Aviv Sourasky Medical Center, Functional Brain Center, The Wohl Institute for Advanced Imaging, Tel Aviv (Israel); Nadav, Guy [Tel Aviv Sourasky Medical Center, Functional Brain Center, The Wohl Institute for Advanced Imaging, Tel Aviv (Israel); Tel Aviv University, Faculty of Engineering, Tel Aviv (Israel); Blumenthal, Deborah T.; Bokstein, Felix [Tel Aviv Sourasky Medical Center, Neuro-Oncology Service, Tel Aviv (Israel); Bashat, Dafna Ben [Tel Aviv Sourasky Medical Center, Functional Brain Center, The Wohl Institute for Advanced Imaging, Tel Aviv (Israel); Tel Aviv University, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv (Israel)
2015-07-15
Cerebral blood volume (CBV) is an important parameter for the assessment of brain tumors, usually obtained using dynamic susceptibility contrast (DSC) MRI. However, this method often suffers from low spatial resolution and high sensitivity to susceptibility artifacts and usually does not take into account the effect of tissue permeability. The plasma volume (v{sub p}) can also be extracted from dynamic contrast enhancement (DCE) MRI. The aim of this study was to investigate whether DCE can be used for the measurement of cerebral blood volume in place of DSC for the assessment of patients with brain tumors. Twenty-eight subjects (17 healthy subjects and 11 patients with glioblastoma) were scanned using DCE and DSC. v{sub p} and CBV values were measured and compared in different brain components in healthy subjects and in the tumor area in patients. Significant high correlations were detected between v{sub p} and CBV in healthy subjects in the different brain components; white matter, gray matter, and arteries, correlating with the known increased tissue vascularity, and within the tumor area in patients. This work proposes the use of DCE as an alternative method to DSC for the assessment of blood volume, given the advantages of its higher spatial resolution, its lower sensitivity to susceptibility artifacts, and its ability to provide additional information regarding tissue permeability. (orig.)
Yu, Zhixian
2013-01-01
The Maxwell stress analysis is used for the calculation of displacement induced temporary electric force of a single charge. This force comes from the variation of the charge's electric intensities that follow Coulomb's inverse square law, and is a kind of displacement dependent temporary restore force. The possibility of natural self-oscillation of a free electron which is driven by this self-force is also suggested.
Aleksandrov, V. Yu.; Arefyev, K. Yu.; Ilchenko, M. A.
2016-07-01
Intensification of mixing between the gaseous working body ejected through a jet nozzle with ambient medium is an important scientific and technical problem. Effective mixing can increase the total efficiency of power and propulsion apparatuses. The promising approach, although poorly studied, is generation of acoustic self-oscillation inside the jet nozzle: this impact might enhance the decay of a supersonic jet and improve the mixing parameters. The paper presents peculiar properties of acoustic self-excitation in jet nozzle. The paper presents results of experimental study performed for a model injector with a set of plates placed into the flow channel, enabling the excitation of acoustic self-oscillations. The study reveals the regularity of under-expanded supersonic jet decay in submerged space for different flow modes. Experimental data support the efficiency of using the jet nozzle with acoustic self-oscillation in application to the systems of gas fuel supply. Experimental results can be used for designing new power apparatuses for aviation and space industry and for process plants.
STROKE VOLUME DYNAMICS IN MALES WITH DIFFERENT FITNESS LEVEL
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Klemen Lavrenčak
2011-08-01
Full Text Available Stroke volume (SV is well known as a routine clinical cardiodynamic measure. It represents the amount of blood ejected by the left ventricle in one beat. Our aim in present study was to evaluate, both, the stroke volume dynamics in males with different fitness level and the relationship between maximal SV value measured during graded exercise testing (GXT on treadmill and VO2 max. One hundred male participants of age 43,06 ± 9.03 years, height 175 ± 8.25 cm, body mass 76.94 ± 15.42 kg, BSA 2.01 ± 0,15 m2 and peak oxygen consumption 46.55 ± 7.03 ml kg-1 min-1 volunteered to participate in this study. All tests were performed in Exercise Physiology Laboratory (University of Ljubljana, Faculty of Sport, The group of expirienced recreational runners differed from sedentary or less trained recreational runners in higher cardiac output (Q; 20.92 ± 4.57 vs 16,90 ± 4,34 l · min-1 (p ≤ 0,001, bigger SV: 136,43 ± 34,59 vs 112,04 ± 30,11 ml · beat -1 (p ≤ 0,001 and higher SI: 73,41 ± 13,42 vs 60,66 ± 11,58 ml · beat -1 · m-2 (p ≤ 0,001. Interestingly, both groups reached maximal SV at practically identical level of test (58.62 ± 17.81 % vs 59,85 ± 14,27 % VO2max. Also, the pattern of SV fall according to VO2max in both groups tested, were similar (12.08 ± 6.26 % vs 11,33 ± 6,23 %.
A Conformal Truncation Framework for Infinite-Volume Dynamics
Katz, Emanuel; Walters, Matthew T
2016-01-01
We present a new framework for studying conformal field theories deformed by one or more relevant operators. The original CFT is described in infinite volume using a basis of states with definite momentum, $P$, and conformal Casimir, $\\mathcal{C}$. The relevant deformation is then considered using lightcone quantization, with the resulting Hamiltonian expressed in terms of this CFT basis. Truncating to states with $\\mathcal{C} \\leq \\mathcal{C}_{\\max}$, one can numerically find the resulting spectrum, as well as other dynamical quantities, such as spectral densities of operators. This method requires the introduction of an appropriate regulator, which can be chosen to preserve the conformal structure of the basis. We check this framework in three dimensions for various perturbative deformations of a free scalar CFT, and for the case of a free $O(N)$ CFT deformed by a mass term and a non-perturbative quartic interaction at large-$N$. In all cases, the truncation scheme correctly reproduces known analytic result...
Fast method for dynamic thresholding in volume holographic memories
Porter, Michael S.; Mitkas, Pericles A.
1998-11-01
It is essential for parallel optical memory interfaces to incorporate processing that dynamically differentiates between databit values. These thresholding points will vary as a result of system noise -- due to contrast fluctuations, variations in data page composition, reference beam misalignment, etc. To maintain reasonable data integrity it is necessary to select the threshold close to its optimal level. In this paper, a neural network (NN) approach is proposed as a fast method of determining the threshold to meet the required transfer rate. The multi-layered perceptron network can be incorporated as part of a smart photodetector array (SPA). Other methods have suggested performing the operation by means of histogram or by use of statistical information. These approaches fail in that they unnecessarily switch to a 1-D paradigm. In this serial domain, global thresholding is pointless since sequence detection could be applied. The discussed approach is a parallel solution with less overhead than multi-rail encoding. As part of this method, a small set of values are designated as threshold determination data bits; these are interleaved with the information data bits and are used as inputs to the NN. The approach has been tested using both simulated data as well as data obtained from a volume holographic memory system. Results show convergence of the training and an ability to generalize upon untrained data for binary and multi-level gray scale datapage images. Methodologies are discussed for improving the performance by a proper training set selection.
A dynamical system of deposit and loan volumes based on the Lotka-Volterra model
Sumarti, N.; Nurfitriyana, R.; Nurwenda, W.
2014-02-01
In this research, we proposed a dynamical system of deposit and loan volumes of a bank using a predator-prey paradigm, where the predator is loan volumes, and the prey is deposit volumes. The existence of loan depends on the existence of deposit because the bank will allocate the loan volume from a portion of the deposit volume. The dynamical systems have been constructed are a simple model, a model with Michaelis-Menten Response and a model with the Reserve Requirement. Equilibria of the systems are analysed whether they are stable or unstable based on their linearised system.
Cardiorenal-endocrine dynamics during and following volume expansion
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Zimmerman, R.S.; Edwards, B.S.; Schwab, T.R.; Heublein, D.M.; Burnett, J.C. Jr.
1987-02-01
The relationship between atrial pressure, atrial natriuretic peptide (ANP), the renin-angiotensin-aldosterone system, and renal hemodynamic and excretory function was examined during and following acute 10% body weight saline volume expansion and measurements were made at 3.3, 6.6, and 10% body weight volume expansion in pentobarbital anesthetized dogs. Right atrial pressure (RAP), pulmonary capillary wedge pressure (PCWP), fractional excretion of Na (FE/sub Na/), and ANP all increased in parallel during volume expansion. Plasma renin activity (PRA) and aldosterone decreased in parallel during 10% volume expansion. ANP, PRA and aldosterone were measured by radioimmunoassay. Following 10% volume expansion, saline was infused at the peak urine flow rate to maintain peak volume expansion. Despite continued saline infusion, RAP, PCWP, and ANP decreased in parallel. In contrast, FE/sub Na/ remained increased, and aldosterone and PRA remained depressed. These studies demonstrate that atrial pressures, ANP, and FE/sub Na/ increase in parallel during volume expansion; this suggests a role for ANP in modulating acute atrial volume overload. During stable volume expansion periods, however, despite a decrease in ANP levels, Na excretion remains elevated, suggesting that non-ANP mechanisms may be important in maintaining natriuresis during stable volume expansion.
Evaluation of Synthetic Self-Oscillating Models of the Vocal Folds
Hubler, Elizabeth P.; Weiland, Kelley S.; Hancock, Adrienne B.; Plesniak, Michael W.
2013-11-01
Approximately 30% of people will suffer from a voice disorder at some point in their lives. The probability doubles for those who rely heavily on their voice, such as teachers and singers. Synthetic vocal fold (VF) models are fabricated and evaluated experimentally in a vocal tract simulator to replicate physiological conditions. Pressure measurements are acquired along the vocal tract and high-speed images are captured at varying flow rates during VF oscillation to facilitate understanding of the characteristics of healthy and damaged VFs. The images are analyzed using a videokymography line-scan technique that has been used to examine VF motion and mucosal wave dynamics in vivo. Clinically relevant parameters calculated from the volume-velocity output of a circumferentially-vented mask (Rothenberg mask) are compared to patient data. This study integrates speech science with engineering and flow physics to overcome current limitations of synthetic VF models to properly replicate normal phonation in order to advance the understanding of resulting flow features, progression of pathological conditions, and medical techniques. Supported by the GW Institute for Biomedical Engineering (GWIBE) and GW Center for Biomimetics and Bioinspired Engineering (COBRE).
Resolving the mystery of milliwatt-threshold opto-mechanical self-oscillation in dual-nanoweb fiber
Koehler, J. R.; Noskov, R. E.; Sukhorukov, A. A.; Butsch, A.; Novoa, D.; Russell, P. St. J.
2016-08-01
It is interesting to pose the question: How best to design an optomechanical device, with no electronics, optical cavity, or laser gain, that will self-oscillate when pumped in a single pass with only a few mW of single-frequency laser power? One might begin with a mechanically resonant and highly compliant system offering very high optomechanical gain. Such a system, when pumped by single-frequency light, might self-oscillate at its resonant frequency. It is well-known, however, that this will occur only if the group velocity dispersion of the light is high enough so that phonons causing pump-to-Stokes conversion are sufficiently dissimilar to those causing pump-to-anti-Stokes conversion. Recently it was reported that two light-guiding membranes 20 μm wide, ˜500 nm thick and spaced by ˜500 nm, suspended inside a glass fiber capillary, oscillated spontaneously at its mechanical resonant frequency (˜6 MHz) when pumped with only a few mW of single-frequency light. This was surprising, since perfect Raman gain suppression would be expected. In detailed measurements, using an interferometric side-probing technique capable of resolving nanoweb movements as small as 10 pm, we map out the vibrations along the fiber and show that stimulated intermodal scattering to a higher-order optical mode frustrates gain suppression, permitting the structure to self-oscillate. A detailed theoretical analysis confirms this picture. This novel mechanism makes possible the design of single-pass optomechanical oscillators that require only a few mW of optical power, no electronics nor any optical resonator. The design could also be implemented in silicon or any other suitable material.
Resolving the mystery of milliwatt-threshold opto-mechanical self-oscillation in dual-nanoweb fiber
Directory of Open Access Journals (Sweden)
J. R. Koehler
2016-08-01
Full Text Available It is interesting to pose the question: How best to design an optomechanical device, with no electronics, optical cavity, or laser gain, that will self-oscillate when pumped in a single pass with only a few mW of single-frequency laser power? One might begin with a mechanically resonant and highly compliant system offering very high optomechanical gain. Such a system, when pumped by single-frequency light, might self-oscillate at its resonant frequency. It is well-known, however, that this will occur only if the group velocity dispersion of the light is high enough so that phonons causing pump-to-Stokes conversion are sufficiently dissimilar to those causing pump-to-anti-Stokes conversion. Recently it was reported that two light-guiding membranes 20 μm wide, ∼500 nm thick and spaced by ∼500 nm, suspended inside a glass fiber capillary, oscillated spontaneously at its mechanical resonant frequency (∼6 MHz when pumped with only a few mW of single-frequency light. This was surprising, since perfect Raman gain suppression would be expected. In detailed measurements, using an interferometric side-probing technique capable of resolving nanoweb movements as small as 10 pm, we map out the vibrations along the fiber and show that stimulated intermodal scattering to a higher-order optical mode frustrates gain suppression, permitting the structure to self-oscillate. A detailed theoretical analysis confirms this picture. This novel mechanism makes possible the design of single-pass optomechanical oscillators that require only a few mW of optical power, no electronics nor any optical resonator. The design could also be implemented in silicon or any other suitable material.
Dynamic Gain Equalizer Based on the H-PDLC Volume Phase Grating
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
The structure and Bragg diffraction characteristics of volume phase gratings based on H-PDLC technology are presented, and the principles and simulation aided design of dynamic gain equalizers with the gratings are discussed.
Nugroho, Bintoro S.; Iskandar, Alexander A.; Malyshev, Victor A.; Knoester, Jasper
2017-01-01
We theoretically investigate the nonlinear optical response of a heterodimer comprising a semiconductor quantum dot strongly coupled to a metal nanoparticle. The quantum dot is considered as a three-level ladder system with ground, one-exciton, and bi-exction states. As compared to the case of a two-level quantum dot model, adding the third (bi-exciton) state produces fascinating effects in the optical response of the hybrid system. Specifically, we demonstrate that the system may exhibit picosecond and sub-picosecond self-oscillations and quasi-chaotic behaviour under single-frequency continuous wave excitation. An isolated semiconductor quantum dot does not show such features. The effects originate from competing one-exciton and bi-exciton transitions in the semiconductor quantum dot, triggered by the self-action of the quantum dot via the metal nanoparticle. The key parameter that governs the phenomena mentioned is the ratio of the self-action strength and the bi-exciton shift. The self-oscillation regime can be achieved in practice, in particular, in a heterodimer comprised of a closely spaced ZnS/ZnSe core-shell quantum dot and a spherical silver nanoparticle. The results may have applications in nanodevices for generating trains of ultrashort optical pulses.
Wind energy conversion. Volume IV. Drive system dynamics
Energy Technology Data Exchange (ETDEWEB)
Martinez-Sanchez, M.; Labuszewski, T.
1978-09-01
The dynamics of the drive system and various approaches to power transmission are described. The effects on performance of using a constant rotor speed as opposed to a rotor speed varying with the wind speed are discussed for various rotor operating schedules and typical wind distributions. The dynamics of the combined rotor, alternator, and drive system are analyzed. Conditions which could lead to electro-dynamic instabilities and desynchronization are discussed as well as means for stabilizing the system. The dynamics of the drive system and important design conditions for various drive systems are discussed, such as location of the alternators, use of hydraulic drive systems and smoothing techniques.
Price dynamics and trading volume: A semiparametric approach
Spierdijk, L.; Nijman, T.E.; van Soest, A.H.O.
2004-01-01
In this paper we investigate the relation between price impact and trading volume for a sample of stocks listed on the New York Stock Exchange. The parametric VAR-models that have been used in the literature impose strong proportionality and symmetry restrictions on the price impact of trades,
Engineering Applications of Computational Fluid Dynamics: Volume 2
Directory of Open Access Journals (Sweden)
Maher A.R. Sadiq Al-Baghdadi
2013-01-01
Full Text Available Chapter 1: CFD Modeling of Methane Reforming in Compact Reformers. Meng Ni Chapter 2: FEM Based Solution of Thermo Fluid Dynamic Phenomena in Solid Oxide Fuel Cells (SOFCS. F. Arpino, A. Carotenuto, N. Massarotti, A. Mauro Chapter 3: Computational Fluid Dynamics in the Development of a 3D Simulator for Testing Pollution Monitoring Robotic Fishes. John Oyekan, Bowen Lu, Huosheng Hu Chapter 4: CFD Applications in Electronic Packaging. C.Y. Khor, Chun-Sean Lau, M.Z. Abdullah Chapter 5: CFD Simulation of Savonius Wind Turbine Operation. Jo?o Vicente Akwa, Adriane Prisco Petry Chapter 6: Intermittency Modelling of Transitional Boundary Layer Flows on Steam and Gas Turbine Blades. Erik Dick, Slawomir Kubacki, Koen Lodefier, Witold Elsner Chapter 7: Numerical Analysis of the Flow through Fitting in Air Conditioning Systems. N.C. Uz?rraga-Rodriguez, A. Gallegos-Mu?oz, J.M. Belman-Flores, J.C. Rubio-Arana Chapter 8: Design and Optimization of Food Processing Equipments using Computational Fluid Dynamics Modeling. N. Chhanwal and C. Anandharamakrishnan Chapter 9: Fuel and Intake Systems Optimization of a Converted LPG Engine: Steady and Unsteady in-Cylinder Flow CFD Investigations and Experiments Validation. M. A. Jemni, G. Kantchev, Z. Driss, M. S. Abid Chapter 10: Computational Fluid Dynamics Application for Thermal Management in Underground Mines. Agus P. Sasmito, Jundika C. Kurnia, Guan Mengzhao, Erik Birgersson, Arun S. Mujumdar Chapter 11: Computational Fluid Dynamics and its Applications. R.Parthiban, C.Muthuraj, A.Rajakumar
Smith, Simeon L.; Thomson, Scott L.
2010-11-01
The subglottis plays an important role in voice production; however, in general the role of subglottal geometry in phonation is not well understood. This research focuses on studying how subglottic stenosis, or a narrowing of the airway below the vocal folds, affects the response of a self-oscillating computational vocal fold model. Methods are described for computational model development, including stenotic geometry definition from CT scan images, incorporation of the stenosis into a finite element fluid-structure interaction model, and parametric variation of the degree of stenosis severity. Results are presented for a normal (no stenosis) case and five cases of varying degrees of stenosis severity. Qualitative and quantitative comparisons of vocal fold vibratory motion and of flow behavior for the six cases are made, including characterization of flow patterns in the subglottis, glottal width and flow rate time histories, vibration frequency, and airway resistance.
An Unstructured Finite Volume Method for Impact Dynamics of a Thin Plate
Institute of Scientific and Technical Information of China (English)
Weidong Chen; Yanchun Yu
2012-01-01
The examination of an unstructured finite volume method for structural dynamics is assessed for simulations of systematic impact dynamics.A robust display dual-time stepping method is utilized to obtain time accurate solutions.The study of impact dynamics is a complex problem that should consider strength models and state equations to describe the mechanical behavior of materials.The current method has several features.1) Discrete equations of unstructured finite volume method naturally follow the conservation law.2)Display dual-time stepping method is suitable for the analysis of impact dynamic problems of time accurate solutions.3) The method did not produce grid distortion when large deformation appeared.The method is validated by the problem of impact dynamics of an elastic plate with initial conditions and material properties.The results validate the finite element numerical data.
The Water to Solute Permeability Ratio Governs the Osmotic Volume Dynamics in Beetroot Vacuoles
Vitali, Victoria; Sutka, Moira; Amodeo, Gabriela; Chara, Osvaldo; Ozu, Marcelo
2016-01-01
Plant cell vacuoles occupy up to 90% of the cell volume and, beyond their physiological function, are constantly subjected to water and solute exchange. The osmotic flow and vacuole volume dynamics relies on the vacuole membrane -the tonoplast- and its capacity to regulate its permeability to both water and solutes. The osmotic permeability coefficient (Pf) is the parameter that better characterizes the water transport when submitted to an osmotic gradient. Usually, Pf determinations are made in vitro from the initial rate of volume change, when a fast (almost instantaneous) osmolality change occurs. When aquaporins are present, it is accepted that initial volume changes are only due to water movements. However, in living cells osmotic changes are not necessarily abrupt but gradually imposed. Under these conditions, water flux might not be the only relevant driving force shaping the vacuole volume response. In this study, we quantitatively investigated volume dynamics of isolated Beta vulgaris root vacuoles under progressively applied osmotic gradients at different pH, a condition that modifies the tonoplast Pf. We followed the vacuole volume changes while simultaneously determining the external osmolality time-courses and analyzing these data with mathematical modeling. Our findings indicate that vacuole volume changes, under progressively applied osmotic gradients, would not depend on the membrane elastic properties, nor on the non-osmotic volume of the vacuole, but on water and solute fluxes across the tonoplast. We found that the volume of the vacuole at the steady state is determined by the ratio of water to solute permeabilites (Pf/Ps), which in turn is ruled by pH. The dependence of the permeability ratio on pH can be interpreted in terms of the degree of aquaporin inhibition and the consequently solute transport modulation. This is relevant in many plant organs such as root, leaves, cotyledons, or stems that perform extensive rhythmic growth movements
The water to solute permeability ratio governs the osmotic volume dynamics in beetroot vacuoles
Directory of Open Access Journals (Sweden)
Victoria Vitali
2016-09-01
Full Text Available Plant cell vacuoles occupy up to 90% of the cell volume and, beyond their physiological function, are constantly subjected to water and solute exchange. The osmotic flow and vacuole volume dynamics relies on the vacuole membrane -the tonoplast- and its capacity to regulate its permeability to both water and solutes. The osmotic permeability coefficient (Pf is the parameter that better characterizes the water transport when submitted to an osmotic gradient. Usually, Pf determinations are made in vitro from the initial rate of volume change, when a fast (almost instantaneous osmolality change occurs. When aquaporins are present, it is accepted that initial volume changes are only due to water movements. However, in living cells osmotic changes are not necessarily abrupt but gradually imposed. Under these conditions, water flux might not be the only relevant driving force shaping the vacuole volume response. In this study, we quantitatively investigated volume dynamics of isolated Beta vulgaris root vacuoles under progressively applied osmotic gradients at different pH, a condition that modifies the tonoplast Pf. We followed the vacuole volume changes while simultaneously determining the external osmolality time-courses and analyzing these data with mathematical modelling. Our findings indicate that vacuole volume changes, under progressively applied osmotic gradients, would not depend on the membrane elastic properties, nor on the non-osmotic volume of the vacuole, but on water and solute fluxes across the tonoplast. We found that the volume of the vacuole at the steady state is determined by the ratio of water to solute permeabilites (Pf/Ps, which in turn is ruled by pH. The dependence of the permeability ratio on pH can be interpreted in terms of the degree of aquaporin inhibition and the consequently solute transport modulation. This is relevant in many plant organs such as root, leaves, cotyledons or stems that perform extensive rhythmic
Self-oscillating Galvanic Isolated Bidirectional Very High Frequency DC-DC Converter
DEFF Research Database (Denmark)
Pedersen, Jeppe Arnsdorf; Madsen, Mickey Pierre; Knott, Arnold
2015-01-01
This paper describes a galvanic isolated bidirectional Very High Frequency (VHF = 30 MHz - 300MHz) ClassE converter. The reason for increasing the switching frequency is to minimize the passive components in the converter. To make the converter topology bidirectional the rectifier has...... conduction mode. The designed converter operates at a switching frequency of 35.6 MHz, which is well within the VHF range. The same converter is also implemented with PCB embedded inductors to minimize cost and the physical volume of the total converter....
Automatic extraction of forward stroke volume using dynamic PET/CT
DEFF Research Database (Denmark)
Harms, Hans; Tolbod, Lars Poulsen; Hansson, Nils Henrik;
Background: Dynamic PET can be used to extract forward stroke volume (FSV) by the indicator dilution principle. The technique employed can be automated and is in theory independent on the tracer used and may therefore be added to any dynamic cardiac PET protocol. The aim of this study was to vali......Background: Dynamic PET can be used to extract forward stroke volume (FSV) by the indicator dilution principle. The technique employed can be automated and is in theory independent on the tracer used and may therefore be added to any dynamic cardiac PET protocol. The aim of this study...... was to validate automated methods for extracting FSV directly from dynamic PET studies for two different tracers and to examine potential scanner hardware bias. Methods: 21 subjects underwent a dynamic 27 min 11C-acetate PET scan on a Siemens Biograph TruePoint 64 PET/CT scanner (scanner I). In addition, 8...... subjects underwent a dynamic 6 min 15O-water PET scan followed by a 27 min 11C-acetate PET scan on a GE Discovery ST PET/CT scanner (scanner II). The LV-aortic time-activity curve (TAC) was extracted automatically from dynamic PET data using cluster analysis. The first-pass peak was isolated by automatic...
Relation Between the Cell Volume and the Cell Cycle Dynamics in Mammalian cell
Magno, A. C. G.; Oliveira, I. L.; Hauck, J. V. S.
2016-08-01
The main goal of this work is to add and analyze an equation that represents the volume in a dynamical model of the mammalian cell cycle proposed by Gérard and Goldbeter (2011) [1]. The cell division occurs when the cyclinB/Cdkl complex is totally degraded (Tyson and Novak, 2011)[2] and it reaches a minimum value. At this point, the cell is divided into two newborn daughter cells and each one will contain the half of the cytoplasmic content of the mother cell. The equations of our base model are only valid if the cell volume, where the reactions occur, is constant. Whether the cell volume is not constant, that is, the rate of change of its volume with respect to time is explicitly taken into account in the mathematical model, then the equations of the original model are no longer valid. Therefore, every equations were modified from the mass conservation principle for considering a volume that changes with time. Through this approach, the cell volume affects all model variables. Two different dynamic simulation methods were accomplished: deterministic and stochastic. In the stochastic simulation, the volume affects every model's parameters which have molar unit, whereas in the deterministic one, it is incorporated into the differential equations. In deterministic simulation, the biochemical species may be in concentration units, while in stochastic simulation such species must be converted to number of molecules which are directly proportional to the cell volume. In an effort to understand the influence of the new equation a stability analysis was performed. This elucidates how the growth factor impacts the stability of the model's limit cycles. In conclusion, a more precise model, in comparison to the base model, was created for the cell cycle as it now takes into consideration the cell volume variation
Modelling dynamic liquid-gas systems: Extensions to the volume-of-fluid solver
CSIR Research Space (South Africa)
Heyns, Johan A
2013-06-01
Full Text Available This study presents the extension of the volume-of-fluid solver, interFoam, for improved accuracy and efficiency when modelling dynamic liquid-gas systems. Examples of these include the transportation of liquids, such as in the case of fuel carried...
Mathematical model of diffusion-limited gas bubble dynamics in unstirred tissue with finite volume.
Srinivasan, R Srini; Gerth, Wayne A; Powell, Michael R
2002-02-01
Models of gas bubble dynamics for studying decompression sickness have been developed by considering the bubble to be immersed in an extravascular tissue with diffusion-limited gas exchange between the bubble and the surrounding unstirred tissue. In previous versions of this two-region model, the tissue volume must be theoretically infinite, which renders the model inapplicable to analysis of bubble growth in a finite-sized tissue. We herein present a new two-region model that is applicable to problems involving finite tissue volumes. By introducing radial deviations to gas tension in the diffusion region surrounding the bubble, the concentration gradient can be zero at a finite distance from the bubble, thus limiting the tissue volume that participates in bubble-tissue gas exchange. It is shown that these deviations account for the effects of heterogeneous perfusion on gas bubble dynamics, and are required for the tissue volume to be finite. The bubble growth results from a difference between the bubble gas pressure and an average gas tension in the surrounding diffusion region that explicitly depends on gas uptake and release by the bubble. For any given decompression, the diffusion region volume must stay above a certain minimum in order to sustain bubble growth.
Threshold switching and electrical self-oscillation in niobium oxide films
Liu, Xinjun; Li, Shuai; Nandi, Sanjoy Kumar; Venkatachalam, Dinesh Kumar; Elliman, Robert Glen
2016-09-01
Electrical self-sustained oscillations have been observed in a broad range of two-terminal systems and are of interest as possible building blocks for bio-inspired neuromorphic computing. In this work, we experimentally explore voltage-controlled oscillations in NbOx devices with a particular focus on understanding how the frequency and waveform are influenced by circuit parameters. We also introduce a finite element model of the device based on a Joule-heating induced insulator-metal transition. The electroformed device structure is represented by a cylindrical conductive channel (filament) comprised of NbO/NbO2 zones and surrounded by an Nb2O5-x matrix. The model is shown to reproduce the current-controlled negative differential resistance observed in measured current-voltage curves, and is combined with circuit elements to simulate the waveforms and dynamics of an isolated Pearson-Anson oscillator. Such modeling is shown to provide considerable insight into the relationship between the material response and device and circuit characteristics.
Starikov, E.; Shiktorov, P.; Gružinskis, V.; Marinchio, H.; Palermo, C.; Varani, L.
2015-12-01
We investigate the shortening of the gate-length in submicrometric and nanometric field-effect transistors as a powerful tool to improve their self-oscillations performances in the terahertz frequency region due to the appearance of the Dyakonov-Shur instability. The theoretical model is based on the numerical solution of hydrodynamic equations for the electron transport in FETs/HEMTs channels. We show that a decrease of the gate length allows, on the one hand, to increase the intrinsic resonant frequencies near 1 THz and, on the other hand, to improve the conditions for the onset of the Dyakonov-Shur instability and related phenomena. The small-signal characteristics calculated under constant drain-voltage operation are compared with the drain-voltage self-oscillations calculated under constant drain-current operation.
Gazdzinski, Stefan; Durazzo, Timothy C; Meyerhoff, Dieter J
2005-06-01
Brain shrinkage and its partial reversibility with abstinence is a common neuroimaging finding in alcohol dependent individuals. We used an automated three-dimensional whole brain magnetic resonance imaging method (boundary shift integral) in 23 alcohol dependent individuals to measure the temporal dynamics of cerebral tissue and spinal fluid volume changes over a 12-month interval and to examine the major determinants of brain tissue change rates during abstinence and non-abstinence. We found more rapid brain tissue gain during the first month of sobriety than in the following months. The most rapid volume recovery was observed in abstinent individuals with the greatest baseline brain shrinkage and drinking severity. The rapid reversal of brain volume gains in non-abstinent individuals and tissue volume changes are modulated by duration of abstinence and non-abstinence periods, as well as recency of non-abstinence. Age, family history density of alcoholism, relapse severity, and duration or age of onset of heavy drinking were not major determinants of brain shrinkage and brain volume recovery rates. Treatment providers may use this tangible information to reinforce the biomedical benefits of sobriety. Previous quantitative measurements of brain volumes in alcohol dependent individuals performed after several weeks of abstinence likely underestimated the full extent of chronic alcohol-associated brain shrinkage.
STIFFNESS AND EXCLUDED VOLUME EFFECTS ON CONFORMATION AND DYNAMICS OF POLYMERS: A SIMULATION STUDY
Institute of Scientific and Technical Information of China (English)
An-bang Li; Yuan-gen Yao; Hong Xu
2012-01-01
This work investigates the effects of the excluded volume and especially those of the chain stiffness on the structural and dynamical properties of a model polymer chain.The theoretical framework is the same as in the recent works by Steinhauser et al.,where a Rouse approach is adopted.Our model differs in that our chains have a finite average bending angle.As in the works by Steinhauser et al.,Langevin dynamic simulations were performed without hydrodynamic interactions.Whereas this doesn't impact the static properties we obtain,it also allows us to compare our results on dynamic properties to those predicted by Rouse theory,where hydrodynamic interactions are also neglected.Our results show that the structural properties are very sensitive to the chain stiffness,whereas the dynamic scaling laws remain the same as those by Rouse theory,with the prefactor depending on the persistence length.
On-line dynamic measurement of blood viscosity, hematocrit and change of blood volume
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
Objective: To develop an on-line system for the measurement of blood viscosity and hematocrit. The dynamic changes of the macrovascular blood volumes,microvascular blood volumes and the total blood volume were observed by means of calculating from the testing result. Methods: Applying traditional viscosity measurement principle and specific wavelength optic density measurement method, an on-line system for the measurement of blood viscosity and hematocrit was developed, and the A/D multifunctionai board and the testing circuit were designed by ourselves. The system was validated by experiments both in vitro and in vivo. Therapeutic effects of hypertonic saline dextran solution (HSD) and Lactatic Ringer's solution at the early stage after burn-blast combined injury were compared by this method. Results: The results showed that the system has attained the goal of the design. The changes of the blood viscosity and hematocrit could be detected effectively and continuously. The changes of macrovascular, microvascular and total blood volume could be calculated approximately. Conclusions: The system and the method can continuously on-line test the blood viscosity and hematocrit, and reveal the change and distribution of blood volumes more accurately and dearly in the therapy process by estimating changes of the macrovascular, microvascular and total blood volumes, respectively. It has confirmed that HSD treatment could increase blood pressure and attenuate tissue edema by significantly increasing total blood volume,improving macrocirculatory and microcirculatory blood volumes. This study suggested that it could be desirable to develop an experiment technique based on the method mentioned above.
Energy Technology Data Exchange (ETDEWEB)
Shi, Jingyun, E-mail: shijingyun89179@126.com [Department of Radiology, Shanghai Pulmonary Hospital, Tongji University School of Medicine (China); Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim (Germany); Schmid-Bindert, Gerald, E-mail: gerald.schmid-bindert@medma.uni-heidelberg.de [Division of Surgical Oncology and Thoracic Surgery, Department of Surgery, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim (Germany); Fink, Christian, E-mail: Christian.Fink@akh-celle.de [Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim (Germany); Sudarski, Sonja, E-mail: sonja_sudarski@gmx.de [Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim (Germany); Apfaltrer, Paul, E-mail: Paul.Apfaltrer@medma.uni-heidelberg.de [Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim (Germany); Pilz, Lothar R., E-mail: Lothar.Pilz@medma.uni-heidelberg.de [Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1, 68167 Mannheim (Germany); Liu, Bo, E-mail: bo.liu@siemens.com [Siemens Healthcare, No. 278, Zhouzhu Road, Shanghai, 201318 (China); Haberland, Ulrike, E-mail: ulrike.haberland@siemens.com [Siemens Healthcare Sector, H IM CR R and D PA SC, Siemensstraße 1, 91301 Forchheim (Germany); Klotz, Ernst, E-mail: ernst.klotz@siemens.com [Siemens Healthcare Sector, H IM CR R and D PA SC, Siemensstraße 1, 91301 Forchheim (Germany); and others
2013-12-01
Objective: To evaluate dynamic volume perfusion CT (dVPCT) tumor baseline characteristics of three different subtypes of lung cancer in untreated patients. Materials and methods: 173 consecutive patients (131 men, 42 women; mean age 61 ± 10 years) with newly diagnosed lung cancer underwent dVPCT prior to biopsy. Tumor permeability, blood flow (BF), blood volume (BV) and mean transit time (MTT) were quantitatively assessed as well as tumor diameter and volume. Tumor subtypes were histologically determined and compared concerning their dVPCT results. dVPCT results were correlated to tumor diameter and volume. Results: Histology revealed adenocarcinoma in 88, squamous cell carcinoma in 54 and small cell lung cancer (SCLC) in 31 patients. Tumor permeability was significantly differing between adenocarcinoma, squamous cell carcinoma and SCLC (all p < 0.05). Tumor BF and BV were higher in adenocarcinomathan in SCLC (p = 0.001 and p = 0.0002 respectively). BV was also higher in squamous cell carcinoma compared to SCLC (p = 0.01). MTT was not differing between tumor subtypes. Regarding all tumors, tumor diameter did not correlate with any of the dVPCT parameters, whereas tumor volume was negatively associated with permeability, BF and BV (r = −0.22, −0.24, −0.24, all p < 0.05). In squamous cell carcinoma, tumor diameter und volume correlated with BV (r = 0.53 and r = −0.40, all p < 0.05). In SCLC, tumor diameter und volume correlated with MTT (r = 0.46 and r = 0.39, all p < 0.05). In adenocarcinoma, no association between morphological and functional tumor characteristics was observed. Conclusions: dVPCT parameters are only partially related to tumor diameter and volume and are significantly differing between lung cancer subtypes.
Ryan, Eric D; Everett, Kenneth L; Smith, Doug B; Pollner, Christie; Thompson, Brennan J; Sobolewski, Eric J; Fiddler, Ryan E
2014-11-01
The purpose of this study was to examine the acute effects of different volumes of a dynamic stretching routine on vertical jump (VJ) performance, flexibility and muscular endurance (ME). Twenty-six males (age 22.2 ± 1.3 years) performed three separate randomized conditions: (i) a control (CON) condition (5-min jog + 12 min of resting), (ii) a 5-min jog + a dynamic stretching routine (DS1; 6.7 ± 1.3 min) and (iii) a 5-min jog + a dynamic stretching routine with twice the volume (DS2; 12.1 ± 1.6 min). The dynamic stretching routine included 11 exercises targeting the hip and thigh musculature. VJ performance (jump height and velocity) and flexibility were measured prior to and following all conditions, while ME was measured following all conditions. The DS1 and DS2 conditions increased VJ height and velocity (P0.05). When compared to the CON condition, the DS1 condition did not improve ME (P>0.05), whereas the DS2 condition resulted in a significant (15.6%) decrease in the number of repetitions completed (Pstretching routines lasting approximately 6-12 min performed following a 5-min jog resulted in similar increases in VJ performance and flexibility. However, longer durations of dynamic stretching routines may impair repetitive high-intensity activities. © 2014 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.
Brownian Dynamics of a Suspension of Particles with Constrained Voronoi Cell Volumes
Singh, John P.
2015-06-23
© 2015 American Chemical Society. Solvent-free polymer-grafted nanoparticle fluids consist of inorganic core particles fluidized by polymers tethered to their surfaces. The attachment of the suspending fluid to the particle surface creates a strong penalty for local variations in the fluid volume surrounding the particles. As a model of such a suspension we perform Brownian dynamics of an equilibrium system consisting of hard spheres which experience a many-particle potential proportional to the variance of the Voronoi volumes surrounding each particle (E = α(V
Brownian Dynamics of a Suspension of Particles with Constrained Voronoi Cell Volumes.
Singh, John P; Walsh, Stuart D C; Koch, Donald L
2015-06-23
Solvent-free polymer-grafted nanoparticle fluids consist of inorganic core particles fluidized by polymers tethered to their surfaces. The attachment of the suspending fluid to the particle surface creates a strong penalty for local variations in the fluid volume surrounding the particles. As a model of such a suspension we perform Brownian dynamics of an equilibrium system consisting of hard spheres which experience a many-particle potential proportional to the variance of the Voronoi volumes surrounding each particle (E = α(Vi-V0)(2)). The coefficient of proportionality α can be varied such that pure hard sphere dynamics is recovered as α → 0, while an incompressible array of hairy particles is obtained as α → ∞. As α is increased the distribution of Voronoi volumes becomes narrower, the mean coordination number of the particle increases and the variance in the number of nearest neighbors decreases. The nearest neighbor peaks in the pair distribution function are suppressed and shifted to larger radial separations as the constraint acts to maintain relatively uniform interstitial regions. The structure factor of the model suspension satisfies S(k=0) → 0 as α → ∞ in accordance with expectation for a single component (particle plus tethered fluid) incompressible system. The tracer diffusivity of the particles is reduced by the volume constraint and goes to zero at ϕ ∼ 0.52, indicating an earlier glass transition than has been observed in hard sphere suspensions. The total pressure of the suspension grows in proportion to (αkBT)(1/2) as the strength of the volume-constraint potential grows. This stress arises primarily from the interparticle potential forces, while the hard-sphere collisional contribution to the stress is suppressed by the volume constraint.
Dynamic real-time 4D cardiac MDCT image display using GPU-accelerated volume rendering.
Zhang, Qi; Eagleson, Roy; Peters, Terry M
2009-09-01
Intraoperative cardiac monitoring, accurate preoperative diagnosis, and surgical planning are important components of minimally-invasive cardiac therapy. Retrospective, electrocardiographically (ECG) gated, multidetector computed tomographical (MDCT), four-dimensional (3D + time), real-time, cardiac image visualization is an important tool for the surgeon in such procedure, particularly if the dynamic volumetric image can be registered to, and fused with the actual patient anatomy. The addition of stereoscopic imaging provides a more intuitive environment by adding binocular vision and depth cues to structures within the beating heart. In this paper, we describe the design and implementation of a comprehensive stereoscopic 4D cardiac image visualization and manipulation platform, based on the opacity density radiation model, which exploits the power of modern graphics processing units (GPUs) in the rendering pipeline. In addition, we present a new algorithm to synchronize the phases of the dynamic heart to clinical ECG signals, and to calculate and compensate for latencies in the visualization pipeline. A dynamic multiresolution display is implemented to enable the interactive selection and emphasis of volume of interest (VOI) within the entire contextual cardiac volume and to enhance performance, and a novel color and opacity adjustment algorithm is designed to increase the uniformity of the rendered multiresolution image of heart. Our system provides a visualization environment superior to noninteractive software-based implementations, but with a rendering speed that is comparable to traditional, but inferior quality, volume rendering approaches based on texture mapping. This retrospective ECG-gated dynamic cardiac display system can provide real-time feedback regarding the suspected pathology, function, and structural defects, as well as anatomical information such as chamber volume and morphology.
Dynamics at Solid State Surfaces and Interfaces, Volume 1 Current Developments
Bovensiepen, Uwe; Wolf, Martin
2010-01-01
This two-volume work covers ultrafast structural and electronic dynamics of elementary processes at solid surfaces and interfaces, presenting the current status of photoinduced processes. Providing valuable introductory information for newcomers to this booming field of research, it investigates concepts and experiments, femtosecond and attosecond time-resolved methods, as well as frequency domain techniques. The whole is rounded off by a look at future developments.
Analysis of flexible aircraft longitudinal dynamics and handling qualities. Volume 2: Data
Waszak, M. R.; Schmidt, D. K.
1985-01-01
Two analysis methods are applied to a family of flexible aircraft in order to investigate how and when structural (especially dynamic aeroelastic) effects affect the dynamic characteristics of aircraft. The first type of analysis is an open loop modal analysis technique. This method considers the effect of modal residue magnitudes on determining vehicle handling qualities. The second method is a pilot in the loop analysis procedure that considers several closed loop system characteristics. Both analyses indicated that dynamic aeroelastic effects caused a degradation in vehicle tracking performance, based on the evaluation of some simulation results. Volume 2 consists of the presentation of the state variable models of the flexible aircraft configurations used in the analysis applications mode shape plots for the structural modes, numerical results from the modal analysis frequency response plots from the pilot in the loop analysis and a listing of the modal analysis computer program.
Directory of Open Access Journals (Sweden)
Christina Haubrich
Full Text Available Several studies have shown that the progression of communicating hydrocephalus is associated with diminished cerebral perfusion and microangiopathy. If communicating hydrocephalus similarly alters the cerebrospinal fluid circulation and cerebral blood flow, both may be related to intracranial mechanoelastic properties as, for instance, the volume pressure compliance. Twenty-three shunted patients with communicating hydrocephalus underwent intraventricular constant-flow infusion with Hartmann's solution. The monitoring included transcranial Doppler (TCD flow velocities (FV in the middle (MCA and posterior cerebral arteries (PCA, intracranial pressure (ICP, and systemic arterial blood pressure (ABP. The analysis covered cerebral perfusion pressure (CPP, the index of pressure-volume compensatory reserve (RAP, and phase shift angles between Mayer waves (3 to 9 cpm in ABP and MCA-FV or PCA-FV. Due to intraventricular infusion, the pressure-volume reserve was exhausted (RAP 0.84+/-0.1 and ICP was increased from baseline 11.5+/-5.6 to plateau levels of 20.7+/-6.4 mmHg. The ratio dRAP/dICP distinguished patients with large 0.1+/-0.01, medium 0.05+/-0.02, and small 0.02+/-0.01 intracranial volume compliances. Both M wave phase shift angles (r = 0.64; p<0.01 and CPP (r = 0.36; p<0.05 displayed a gradual decline with decreasing dRAP/dICP gradients. This study showed that in communicating hydrocephalus, CPP and dynamic cerebral autoregulation in particular, depend on the volume-pressure compliance. The results suggested that the alteration of mechanoelastic characteristics contributes to a reduced cerebral perfusion and a loss of autonomy of cerebral blood flow regulation. Results warrant a prospective TCD follow-up to verify whether the alteration of dynamic cerebral autoregulation may indicate a progression of communicating hydrocephalus.
Lammi, Matthew R; Ciccolella, David; Marchetti, Nathaniel; Kohler, Malcolm; Criner, Gerard J
2012-10-01
Stroke volume augmentation during exercise is limited in chronic obstructive pulmonary disease patients because of decreased preload from dynamic hyperinflation (DH). We hypothesised that oxygen pulse and pulse pressure (PP) improve following lung volume reduction surgery (LVRS), and the magnitude of improvement correlates with reduction in DH. We compared 16 emphysema patients undergoing LVRS with six emphysema patients not undergoing LVRS. Oxygen pulse and PP were calculated from maximal cardiopulmonary exercise tests at baseline and 6 months. End-expiratory lung volume (EELV)/total lung capacity (TLC) represented DH. Comparisons were made between baseline and 6 months at metabolic isotimes (per cent maximal carbon dioxide production (V'(CO(2),max))). At baseline, the LVRS group was older with higher forced expiratory volume in 1 s, but had similar hyperinflation to the non-LVRS group. At 6 months, oxygen pulse (50%, 75%, and 100% V'(CO(2),max)) and PP (50% and 75% V'(CO(2),max)) increased in the LVRS, but not in the non-LVRS group. Baseline functional residual capacity/TLC inversely correlated with resting oxygen pulse (r= -0.449, p=0.04). Decreased EELV/TLC correlated with increased oxygen pulse at 75% (r= -0.487, p=0.02) and 100% V'(CO(2),max) (r= -0.548, p=0.008). LVRS led to increased oxygen pulse and PP during exercise at metabolic isotimes 6 months following surgery. Reductions in DH correlated with increases in oxygen pulse during exercise. Reducing lung volume may improve stroke volume response to exercise by decreasing DH.
Automated three-dimensional single cell phenotyping of spindle dynamics, cell shape, and volume
Plumb, Kemp; Pelletier, Vincent; Kilfoil, Maria L
2015-01-01
We present feature finding and tracking algorithms in 3D in living cells, and demonstrate their utility to measure metrics important in cell biological processes. We developed a computational imaging hybrid approach that combines automated three-dimensional tracking of point-like features with surface determination from which cell (or nuclear) volume, shape, and planes of interest can be extracted. After validation, we applied the technique to real space context-rich dynamics of the mitotic spindle, and cell volume and its relationship to spindle length, in dividing living cells. These methods are additionally useful for automated segregation of pre-anaphase and anaphase spindle populations in budding yeast. We found that genetic deletion of the yeast kinesin-5 mitotic motor cin8 leads to large mother and daughter cells that were indistinguishable based on size, and that in those cells the spindle length becomes uncorrelated with cell size. The technique can be used to visualize and quantify tracked feature c...
ECONOMETRIC MODELING OF THE DYNAMICS OF VOLUMES HYDROCARBONS OF SMALL OIL AND GAS ENTERPRISES
Directory of Open Access Journals (Sweden)
GORLOV A.V.
2015-01-01
Full Text Available In this paper investigates the principles of functioning of small oil and gas enterprises of Russia. The basic characteristics and socio-economic tasks performed by the small oil and gas enterprises. Made correlation and regression analysis, a result of which the pair correlation coefficients between the indicator of development of small oil and gas enterprises (volumes hydrocarbons and the factors that characterize the work environment of their operation; built regressions, describing the process of development of small oil and gas enterprises. With a view to forecasting the development of small oil and gas enterprises built production function of Cobb-Douglas and selected econometric model, has good predictive properties. Made predictive calculations dynamics of volumes hydrocarbons of small oil and gas enterprises on formulating scenarios for the planning period (2015-2016 years.
Energy Technology Data Exchange (ETDEWEB)
Müller, C.; Hughes, E. D.; Niederauer, G. F.; Wilkening, H.; Travis, J. R.; Spore, J. W.; Royl, P.; Baumann, W.
1998-10-01
Los Alamos National Laboratory (LANL) and Forschungszentrum Karlsruhe (FzK) are developing GASFLOW, a three-dimensional (3D) fluid dynamics field code as a best- estimate tool to characterize local phenomena within a flow field. Examples of 3D phenomena include circulation patterns; flow stratification; hydrogen distribution mixing and stratification; combustion and flame propagation; effects of noncondensable gas distribution on local condensation and evaporation; and aerosol entrainment, transport, and deposition. An analysis with GASFLOW will result in a prediction of the gas composition and discrete particle distribution in space and time throughout the facility and the resulting pressure and temperature loadings on the walls and internal structures with or without combustion. A major application of GASFLOW is for predicting the transport, mixing, and combustion of hydrogen and other gases in nuclear reactor containment and other facilities. It has been applied to situations involving transporting and distributing combustible gas mixtures. It has been used to study gas dynamic behavior in low-speed, buoyancy-driven flows, as well as sonic flows or diffusion dominated flows; and during chemically reacting flows, including deflagrations. The effects of controlling such mixtures by safety systems can be analyzed. The code version described in this manual is designated GASFLOW 2.1, which combines previous versions of the United States Nuclear Regulatory Commission code HMS (for Hydrogen Mixing Studies) and the Department of Energy and FzK versions of GASFLOW. The code was written in standard Fortran 90. This manual comprises three volumes. Volume I describes the governing physical equations and computational model. Volume II describes how to use the code to set up a model geometry, specify gas species and material properties, define initial and boundary conditions, and specify different outputs, especially graphical displays. Sample problems are included. Volume
NONLINEAR DYNAMICS MODFLING OF MECHANICAL PERIODICITY OF END DIASTOLIC VOLUME OF LEFT VENTRICLE
Institute of Scientific and Technical Information of China (English)
许世雄; 毛晓春
2001-01-01
The cardiovascular system with a lumped parameter model is treated, in which the Starling model is used to simulate left ventricle and the four-element Burattini & Gnudi model is used in the description of arterial system. Moreover, the feedback action of arterial pressure on cardiac cycle is taken into account. The phenomenon of mechanical periodicity (MP) of end diastolic volume (EDV) of left ventricle is successfully simulated by solving a series of one-dimensional discrete nonlinear dynamical equations. The effects of cardiovascular parameters on MP is also discussed.
Large-Scale Context-Aware Volume Navigation using Dynamic Insets
Al-Awami, Ali
2012-07-01
Latest developments in electron microscopy (EM) technology produce high resolution images that enable neuro-scientists to identify and put together the complex neural connections in a nervous system. However, because of the massive size and underlying complexity of this kind of data, processing, navigation and analysis suffer drastically in terms of time and effort. In this work, we propose the use of state-of- the-art navigation techniques, such as dynamic insets, built on a peta-scale volume visualization framework to provide focus and context-awareness to help neuro-scientists in their mission to analyze, reconstruct, navigate and explore EM neuroscience data.
Applying the dynamic cone penetrometer (DCP) design method to low volume roads
CSIR Research Space (South Africa)
Paige-Green, P
2011-07-01
Full Text Available in one hand and assessing the ?cohesion?. At OMC (damp) the material can be squeezed into a ?sausage? that remains intact. In the very dry state (less than about 25% of OMC), the material is dusty and loose and has absolutely no cohesion. In the dry... state (about 50% of OMC), the material will have no cohesion P. Paige-Green / Applying the Dynamic Cone Penetrometer Design Method to Low Volume Roads 423 when squeezed into a sausage whereas in the moist state (about 75% of OMC), the material may just...
Dynamics of impurities in a three-dimensional volume-preserving map.
Das, Swetamber; Gupte, Neelima
2014-07-01
We study the dynamics of inertial particles in three-dimensional incompressible maps, as representations of volume-preserving flows. The impurity dynamics has been modeled, in the Lagrangian framework, by a six-dimensional dissipative bailout embedding map. The fluid-parcel dynamics of the base map is embedded in the particle dynamics governed by the map. The base map considered for the present study is the Arnold-Beltrami-Childress (ABC) map. We consider the behavior of the system both in the aerosol regime, where the density of the particle is larger than that of the base flow, as well as the bubble regime, where the particle density is less than that of the base flow. The phase spaces in both the regimes show rich and complex dynamics with three types of dynamical behaviors--chaotic structures, regular orbits, and hyperchaotic regions. In the one-action case, the aerosol regime is found to have periodic attractors for certain values of the dissipation and inertia parameters. For the aerosol regime of the two-action ABC map, an attractor merging and widening crisis is identified using the bifurcation diagram and the spectrum of Lyapunov exponents. After the crisis an attractor with two parts is seen, and trajectories hop between these parts with period 2. The bubble regime of the embedded map shows strong hyperchaotic regions as well as crisis induced intermittency with characteristic times between bursts that scale as a power law behavior as a function of the dissipation parameter. Furthermore, we observe a riddled basin of attraction and unstable dimension variability in the phase space in the bubble regime. The bubble regime in the one-action case shows similar behavior. This study of a simple model of impurity dynamics may shed light upon the transport properties of passive scalars in three-dimensional flows. We also compare our results with those seen earlier in two-dimensional flows.
Kuzishchin, V. F.; Tsarev, V. S.
2014-04-01
The problem of automatically tuning controllers in an operating control system is considered. Two methods for quickly determining the model parameters with calculating the plant model and the optimal controller tuning parameters in real time are proposed for the preliminary controller tuning stage: from the experimentally obtained plant response to an impulse disturbance and from two periods of self-oscillations excited in the mode of two-position control. The PID controller tunings are determined using the calculation algorithm of indirect frequency optimality indicators. The results from checking the serviceability of the proposed method in a system fitted with an industry-grade controller are presented.
Borg, Michael; Melchior Hansen, Anders; Bredmose, Henrik
2016-09-01
Designing floating substructures for the next generation of 10MW and larger wind turbines has introduced new challenges in capturing relevant physical effects in dynamic simulation tools. In achieving technically and economically optimal floating substructures, structural flexibility may increase to the extent that it becomes relevant to include in addition to the standard rigid body substructure modes which are typically described through linear radiation-diffraction theory. This paper describes a method for the inclusion of substructural flexibility in aero-hydro-servo-elastic dynamic simulations for large-volume substructures, including wave-structure interactions, to form the basis of deriving sectional loads and stresses within the substructure. The method is applied to a case study to illustrate the implementation and relevance. It is found that the flexible mode is significantly excited in an extreme event, indicating an increase in predicted substructure internal loads.
Waszak, M. R.; Schmidt, D. S.
1985-01-01
As aircraft become larger and lighter due to design requirements for increased payload and improved fuel efficiency, they will also become more flexible. For highly flexible vehicles, the handling qualities may not be accurately predicted by conventional methods. This study applies two analysis methods to a family of flexible aircraft in order to investigate how and when structural (especially dynamic aeroelastic) effects affect the dynamic characteristics of aircraft. The first type of analysis is an open loop model analysis technique. This method considers the effects of modal residue magnitudes on determining vehicle handling qualities. The second method is a pilot in the loop analysis procedure that considers several closed loop system characteristics. Volume 1 consists of the development and application of the two analysis methods described above.
DEFF Research Database (Denmark)
Harms, Hans; Hansson, Nils Henrik Stubkjær; Tolbod, Lars Poulsen;
2016-01-01
-gated dynamic cardiac PET. METHODS: Thirty-five patients with aortic-valve stenosis and 10 healthy controls (HC) underwent a 27-min 11C-acetate PET/CT scan and cardiac magnetic resonance imaging (CMR). HC were scanned twice to assess repeatability. Parametric images of uptake rate K1 and the blood pool were......LV and WT only and an overestimation for LVEF at lower values. Intra- and inter-observer correlations were >0.95 for all PET measurements. PET repeatability accuracy in HC was comparable to CMR. CONCLUSION: LV mass and volumes are accurately and automatically generated from dynamic 11C-acetate PET without...... ECG-gating. This method can be incorporated in a standard routine without any additional workload and can, in theory, be extended to other PET tracers....
Arendsen, A. R. J.; Versteeg, G. F.
2009-01-01
Dynamic models for process design, optimization, and control usually solve a set of heat and/or mass balances as a function of time and/or position in the process. To obtain more robust dynamic models and to minimize the amount of assumptions, internal energy, volume, and amount of moles are chosen
Arendsen, A. R. J.; Versteeg, G. F.
2009-01-01
Dynamic models for process design, optimization, and control usually solve a set of heat and/or mass balances as a function of time and/or position in the process. To obtain more robust dynamic models and to minimize the amount of assumptions, internal energy, volume, and amount of moles are chosen
An upwind vertex centred Finite Volume solver for Lagrangian solid dynamics
Aguirre, Miquel; Gil, Antonio J.; Bonet, Javier; Lee, Chun Hean
2015-11-01
A vertex centred Jameson-Schmidt-Turkel (JST) finite volume algorithm was recently introduced by the authors (Aguirre et al., 2014 [1]) in the context of fast solid isothermal dynamics. The spatial discretisation scheme was constructed upon a Lagrangian two-field mixed (linear momentum and the deformation gradient) formulation presented as a system of conservation laws [2-4]. In this paper, the formulation is further enhanced by introducing a novel upwind vertex centred finite volume algorithm with three key novelties. First, a conservation law for the volume map is incorporated into the existing two-field system to extend the range of applications towards the incompressibility limit (Gil et al., 2014 [5]). Second, the use of a linearised Riemann solver and reconstruction limiters is derived for the stabilisation of the scheme together with an efficient edge-based implementation. Third, the treatment of thermo-mechanical processes through a Mie-Grüneisen equation of state is incorporated in the proposed formulation. For completeness, the study of the eigenvalue structure of the resulting system of conservation laws is carried out to demonstrate hyperbolicity and obtain the correct time step bounds for non-isothermal processes. A series of numerical examples are presented in order to assess the robustness of the proposed methodology. The overall scheme shows excellent behaviour in shock and bending dominated nearly incompressible scenarios without spurious pressure oscillations, yielding second order of convergence for both velocities and stresses.
Pathak, Harshavardhana S.; Shukla, Ratnesh K.
2016-08-01
A high-order adaptive finite-volume method is presented for simulating inviscid compressible flows on time-dependent redistributed grids. The method achieves dynamic adaptation through a combination of time-dependent mesh node clustering in regions characterized by strong solution gradients and an optimal selection of the order of accuracy and the associated reconstruction stencil in a conservative finite-volume framework. This combined approach maximizes spatial resolution in discontinuous regions that require low-order approximations for oscillation-free shock capturing. Over smooth regions, high-order discretization through finite-volume WENO schemes minimizes numerical dissipation and provides excellent resolution of intricate flow features. The method including the moving mesh equations and the compressible flow solver is formulated entirely on a transformed time-independent computational domain discretized using a simple uniform Cartesian mesh. Approximations for the metric terms that enforce discrete geometric conservation law while preserving the fourth-order accuracy of the two-point Gaussian quadrature rule are developed. Spurious Cartesian grid induced shock instabilities such as carbuncles that feature in a local one-dimensional contact capturing treatment along the cell face normals are effectively eliminated through upwind flux calculation using a rotated Hartex-Lax-van Leer contact resolving (HLLC) approximate Riemann solver for the Euler equations in generalized coordinates. Numerical experiments with the fifth and ninth-order WENO reconstructions at the two-point Gaussian quadrature nodes, over a range of challenging test cases, indicate that the redistributed mesh effectively adapts to the dynamic flow gradients thereby improving the solution accuracy substantially even when the initial starting mesh is non-adaptive. The high adaptivity combined with the fifth and especially the ninth-order WENO reconstruction allows remarkably sharp capture of
Dynamic volume changes in astrocytes are an intrinsic phenomenon mediated by bicarbonate ion flux.
Directory of Open Access Journals (Sweden)
Clare M Florence
Full Text Available Astrocytes, the major type of non-neuronal cells in the brain, play an important functional role in extracellular potassium ([K(+](o and pH homeostasis. Pathological brain states that result in [K(+](o and pH dysregulation have been shown to cause astrocyte swelling. However, whether astrocyte volume changes occur under physiological conditions is not known. In this study we used two-photon imaging to visualize real-time astrocyte volume changes in the stratum radiatum of the hippocampus CA1 region. Astrocytes were observed to swell by 19.0±0.9% in response to a small physiological increase in the concentration of [K(+](o (3 mM. Astrocyte swelling was mediated by the influx of bicarbonate (HCO(3- ions as swelling was significantly decreased when the influx of HCO(3- was reduced. We found: 1 in HCO(3- free extracellular solution astrocytes swelled by 5.4±0.7%, 2 when the activity of the sodium-bicarbonate cotransporter (NBC was blocked the astrocytes swelled by 8.3±0.7%, and 3 in the presence of an extracellular carbonic anhydrase (CA inhibitor astrocytes swelled by 11.4±0.6%. Because a significant HCO(3- efflux is known to occur through the γ-amino-butyric acid (GABA channel, we performed a series of experiments to determine if astrocytes were capable of HCO(3- mediated volume shrinkage with GABA channel activation. Astrocytes were found to shrink -7.7±0.5% of control in response to the GABA(A channel agonist muscimol. Astrocyte shrinkage from GABA(A channel activation was significantly decreased to -5.0±0.6% of control in the presence of the membrane-permeant CA inhibitor acetazolamide (ACTZ. These dynamic astrocyte volume changes may represent a previously unappreciated yet fundamental mechanism by which astrocytes regulate physiological brain functioning.
Gong, Mao-lei; Liu, Da-wei; Wang, Xiao-ting; Chen, Xiu-kai
2013-05-07
To explore the value of dynamic arterial elastance (Eadyn) in the predication of arterial pressure response to volume loading in shock patients. A total of 32 patients with pulse indicator continuous cardiac output (PICCO) monitoring at our intensive care unit from January 2011 to December 2012 were retrospectively studied. The decision of fluid replacement was based upon the presence of shock (mean arterial pressure (MAP) ≤ 65 mm Hg, systolic arterial pressure arterial pressure response to volume loading. Significantly different between MAP responders and MAP nonresponders, baseline Eadyn was an effective predictor of MAP increase after volume loading. The area under the ROC curve was 0.95 for the prediction of volume loading on MAP for Eadyn at baseline (P 0.85 predicted a MAP increase after volume administration with a sensitivity of 89.5% and a specificity of 92.3%. Baseline Eadyn may predict accurately arterial pressure response in MAP to volume loading in shock patients.
Pérez-Molina, Manuel; Pérez-Polo, Manuel F.
2014-10-01
This paper analyzes a controlled servomechanism with feedback and a cubic nonlinearity by means of the Bogdanov-Takens and Andronov-Poincaré-Hopf bifurcations, from which steady-state, self-oscillating and chaotic behaviors will be investigated using the center manifold theorem. The system controller is formed by a Proportional plus Integral plus Derivative action (PID) that allows to stabilize and drive to a prescribed set point a body connected to the shaft of a DC motor. The Bogdanov-Takens bifurcation is analyzed through the second Lyapunov stability method and the harmonic-balance method, whereas the first Lyapunov value is used for the Andronov-Poincaré-Hopf bifurcation. On the basis of the results deduced from the bifurcation analysis, we show a procedure to select the parameters of the PID controller so that an arbitrary steady-state position of the servomechanism can be reached even in presence of noise. We also show how chaotic behavior can be obtained by applying a harmonical external torque to the device in self-oscillating regime. The advantage of achieving chaotic behavior is that it can be used so that the system reaches a set point inside a strange attractor with a small control effort. The analytical calculations have been verified through detailed numerical simulations.
Weak and Dynamic GNSS Signal Tracking Strategies for Flight Missions in the Space Service Volume
Jing, Shuai; Zhan, Xingqun; Liu, Baoyu; Chen, Maolin
2016-01-01
Weak-signal and high-dynamics are of two primary concerns of space navigation using GNSS (Global Navigation Satellite System) in the space service volume (SSV). The paper firstly defines a reference assumption third-order phase-locked loop (PLL) as the baseline of an onboard GNSS receiver, and proves the incompetence of this conventional architecture. Then an adaptive four-state Kalman filter (KF)-based algorithm is introduced to realize the optimization of loop noise bandwidth, which can adaptively regulate its filter gain according to the received signal power and line-of-sight (LOS) dynamics. To overcome the matter of losing lock in weak-signal and high-dynamic environments, an open loop tracking strategy aided by an inertial navigation system (INS) is recommended, and the traditional maximum likelihood estimation (MLE) method is modified in a non-coherent way by reconstructing the likelihood cost function. Furthermore, a typical mission with combined orbital maneuvering and non-maneuvering arcs is taken as a destination object to test the two proposed strategies. Finally, the experiment based on computer simulation identifies the effectiveness of an adaptive four-state KF-based strategy under non-maneuvering conditions and the virtue of INS-assisted methods under maneuvering conditions. PMID:27598164
The event-driven constant volume method for particle coagulation dynamics
Institute of Scientific and Technical Information of China (English)
2008-01-01
Monte Carlo (MC) method, which tracks small numbers of the dispersed simulation parti- cles and then describes the dynamic evolution of large numbers of real particles, consti- tutes an important class of methods for the numerical solution of population balance modeling. Particle coagulation dynamics is a complex task for MC. Event-driven MC ex- hibits higher accuracy and efficiency than time-driven MC on the whole. However, these available event-driven MCs track the "equally weighted simulation particle population" and maintain the number of simulated particles within bounds at the cost of "regulating" com- putational domain, which results in some constraints and drawbacks. This study designed the procedure of "differently weighted fictitious particle population" and the corresponding coagulation rule for differently weighted fictitious particles. And then, a new event-driven MC method was promoted to describe the coagulation dynamics between differently weighted fictitious particles, where "constant number scheme" and "stepwise constant number scheme" were developed to maintain the number of fictitious particles within bounds as well as the constant computational domain. The MC is named event-driven constant volume (EDCV) method. The quantitative comparison among several popular MCs shows that the EDCV method has the advantages of computational precision and computational efficiency over other available MCs.
The event-driven constant volume method for particle coagulation dynamics
Institute of Scientific and Technical Information of China (English)
ZHAO HaiBo; ZHENG ChuGuang
2008-01-01
Monte Carlo (MC) method, which tracks small numbers of the dispersed simulation parti-cles and then describes the dynamic evolution of large numbers of real particles, consti-tutes an important class of methods for the numerical solution of population balance modeling. Particle coagulation dynamics is a complex task for MC. Event-driven MC ex-hibits higher accuracy and efficiency than time-driven MC on the whole. However, these available event-driven MCs track the "equally weighted simulation particle population" and maintain the number of simulated particles within bounds at the cost of "regulating" com-putational domain, which results in some constraints and drawbacks. This study designed the procedure of "differently weighted fictitious particle population" and the corresponding coagulation rule for differently weighted fictitious particles. And then, a new event-driven MC method was promoted to describe the coagulation dynamics between differently weighted fictitious particles, where "constant number scheme" and "stepwise constant number scheme" were developed to maintain the number of fictitious particles within bounds as well as the constant computational domain. The MC is named event-driven constant volume (EDCV) method. The quantitative comparison among several popular MCs shows that the EDCV method has the advantages of computational precision and computational efficiency over other available MCs.
Weak and Dynamic GNSS Signal Tracking Strategies for Flight Missions in the Space Service Volume.
Jing, Shuai; Zhan, Xingqun; Liu, Baoyu; Chen, Maolin
2016-09-02
Weak-signal and high-dynamics are of two primary concerns of space navigation using GNSS (Global Navigation Satellite System) in the space service volume (SSV). The paper firstly defines a reference assumption third-order phase-locked loop (PLL) as the baseline of an onboard GNSS receiver, and proves the incompetence of this conventional architecture. Then an adaptive four-state Kalman filter (KF)-based algorithm is introduced to realize the optimization of loop noise bandwidth, which can adaptively regulate its filter gain according to the received signal power and line-of-sight (LOS) dynamics. To overcome the matter of losing lock in weak-signal and high-dynamic environments, an open loop tracking strategy aided by an inertial navigation system (INS) is recommended, and the traditional maximum likelihood estimation (MLE) method is modified in a non-coherent way by reconstructing the likelihood cost function. Furthermore, a typical mission with combined orbital maneuvering and non-maneuvering arcs is taken as a destination object to test the two proposed strategies. Finally, the experiment based on computer simulation identifies the effectiveness of an adaptive four-state KF-based strategy under non-maneuvering conditions and the virtue of INS-assisted methods under maneuvering conditions.
Weak and Dynamic GNSS Signal Tracking Strategies for Flight Missions in the Space Service Volume
Directory of Open Access Journals (Sweden)
Shuai Jing
2016-09-01
Full Text Available Weak-signal and high-dynamics are of two primary concerns of space navigation using GNSS (Global Navigation Satellite System in the space service volume (SSV. The paper firstly defines a reference assumption third-order phase-locked loop (PLL as the baseline of an onboard GNSS receiver, and proves the incompetence of this conventional architecture. Then an adaptive four-state Kalman filter (KF-based algorithm is introduced to realize the optimization of loop noise bandwidth, which can adaptively regulate its filter gain according to the received signal power and line-of-sight (LOS dynamics. To overcome the matter of losing lock in weak-signal and high-dynamic environments, an open loop tracking strategy aided by an inertial navigation system (INS is recommended, and the traditional maximum likelihood estimation (MLE method is modified in a non-coherent way by reconstructing the likelihood cost function. Furthermore, a typical mission with combined orbital maneuvering and non-maneuvering arcs is taken as a destination object to test the two proposed strategies. Finally, the experiment based on computer simulation identifies the effectiveness of an adaptive four-state KF-based strategy under non-maneuvering conditions and the virtue of INS-assisted methods under maneuvering conditions.
Kim, Dongmin; Mun, Jeong-Beom; Kim, Eun Young
2013-01-01
Occurrence of dynamic left ventricular outflow tract (LVOT) obstruction is not infrequent in critically ill patients, and it is associated with potential danger. Here, we report a case of transient heart failure with hemodynamic deterioration paradoxically induced by extreme dehydration. This article describes clinical features of the patient and echocardiographic findings of dynamic LVOT obstruction and significant mitral regurgitation caused by systolic anterior motion of the mitral valve in a volume-depleted heart. PMID:23709446
Arendsen, A. R. J.; Versteeg, G. F.
2009-01-01
Dynamic models for process design, optimization, and control usually solve a set of heat and/or mass balances as a function of time and/or position in the process. To obtain more robust dynamic models and to minimize the amount of assumptions, internal energy, volume, and amount of moles are chosen as states for the conservation laws of the dynamic model. Temperature, pressure, and the amount and composition of the phases are calculated on the basis of these states at every time step. The Red...
Study of optimal exposure windows using 320-Detector rows dynamic volume CT
Directory of Open Access Journals (Sweden)
Gang Sun
2010-12-01
Full Text Available Gang Sun1, Min Li1, Li Li1, Guo-ying Li1, Zhi-wei Jing21Departments of Medical Imaging, 2Medical Statistics, Jinan Military General Hospital, Shandong Province, ChinaAbstract: The purpose of this study was to determine the optimal electrocardiographic (ECG pulsing windows and evaluate the effect on reduced dose and accuracy using 320-detector rows dynamic volume computed tomography (DVCT. A total of 170 patients were prospectively studied. The optimal reconstruction windows were analyzed in 76 patients scanned using retrospective ECG gating. Forty-seven patients were scanned by the predicted triggering windows. The optimal positions of exposure intervals according to different heart rates were evaluated. Optimal image quality, radiation dose, and diagnostic accuracy were then investigated by applying optimal triggering windows. The optimal ECG pulsing windows were determined as follows: when heart rate was <70 beats per minute, the exposure windows should be preset at 60%–80%; for a heart rate 70–90 beats per minute at 70%–90%; and for a heart rate ≥90 beats per minute at 30%–50%. The radiation dose for patients scanned with prospective ECG gating was significantly lower (5.9 versus 12.9 mSv, P < 0.001. However, because two or three heart beats were needed when heart rate was >70 beats per minute, the radiation dose increased with increasing heart rate for both retrospective and prospective ECG gating (r = 0.64, P < 0.001 and r = 0.59, P < 0.001, respectively. On the basis of a per segment analysis, overall sensitivity was 98.0% (49/50, specificity was 99.2% (602/607, the positive predictive value was 90.7% (49/54, and the negative predictive value was 99.8% (602/603. In conclusion, DVCT has the potential to provide high image quality across a wide range of heart rates using an optimized ECG pulsing window. However, it is recommended to control heart rate below 70 beats per minute, if possible, to decrease the radiation dose
Energy Technology Data Exchange (ETDEWEB)
Delcourte, S
2007-09-15
We aim to develop a finite volume method which applies to a greater class of meshes than other finite volume methods, restricted by orthogonality constraints. We build discrete differential operators over the three staggered tessellations needed for the construction of the method. These operators verify some analogous properties to those of the continuous operators. At first, the method is applied to the Div-Curl problem, which can be viewed as a building block of the Stokes problem. Then, the Stokes problem is dealt with with various boundary conditions. It is well known that when the computational domain is polygonal and non-convex, the order of convergence of numerical methods is deteriorated. Consequently, we have studied how an appropriate local refinement is able to restore the optimal order of convergence for the Laplacian problem. At last, we have discretized the non-linear Navier-Stokes problem, using the rotational formulation of the convection term, associated to the Bernoulli pressure. With an iterative algorithm, we are led to solve a saddle-point problem at each iteration. We give a particular interest to this linear problem by testing some pre-conditioners issued from finite elements, which we adapt to our method. Each problem is illustrated by numerical results on arbitrary meshes, such as strongly non-conforming meshes. (author)
Latest Developments With the Cubed-Sphere Finite-Volume Dynamical Core
Putman, W. M.; Lin, S.
2008-12-01
The hydrostatic finite-volume (FV) dycore [Lin (2004)] has been implemented on the cubed-sphere geometry [Putman and Lin (2007)]. This implementation was intended to address the scalability limitations of the original FV dycore developed for the latitude-longitude grid. The improved parallelism of the cubed-sphere dynamical core has poised the FV dycore to efficiently address high-resolution climate, weather and data- assimilation problems on today's emerging peta-scale computing platforms. In addition, the FV dycore has been extended to the fully compressible non-hydrostatic flow (essentially the un-approximated Euler equations on the sphere) [Lin (2008)]. We will provide an overview of the current state of development, and implementation within parent models at NOAA/GFDL and NASA/GMAO, including shared use of modeling frameworks including the Flexible Modeling System (FMS) at NOAA and the Earth System Modeling Framework at NASA. Further science enhancements to the FV dycore will be discussed, including high-order scale selective explicit diffusion options and vertical remapping options from the floating Lagrangian to Eulerian reference coordinates. Results will be based on idealized baroclinic tests, aqua-planet and AMIP simulations.
AFDM: An advanced fluid-dynamics model. Volume 6: EOS-AFDM interface
Energy Technology Data Exchange (ETDEWEB)
Henneges, G.; Kleinheins, S. [comps.] [Kernforschungszentrum Karlsruhe (Germany)
1994-01-01
This volume of the Advanced Fluid-Dynamics Model (AFDM) documents the modeling of the equation of state (EOS) in the code. The authors present an overview of the basic concepts underlying the thermodynamics modeling and resulting EOS, which is a set of relations between the thermodynamic properties of materials. The AFDM code allows for multiphase-multimaterial systems, which they explore in three phase models: two-material solid, two-material liquid, and three-material vapor. They describe and compare two ways of specifying the EOS of materials: (1) as simplified analytic expressions, or (2) as tables that precisely describe the properties of materials and their interactions for mechanical equilibrium. Either of the two EOS models implemented in AFDM can be selected by specifying the option when preprocessing the source code for compilation. Last, the authors determine thermophysical properties such as surface tension, thermal conductivities, and viscosities in the model for the intracell exchanges of AFDM. Specific notations, routines, EOS data, plots, test results, and corrections to the code are available in the appendices.
Schwing, Alan Michael
For computational fluid dynamics, the governing equations are solved on a discretized domain of nodes, faces, and cells. The quality of the grid or mesh can be a driving source for error in the results. While refinement studies can help guide the creation of a mesh, grid quality is largely determined by user expertise and understanding of the flow physics. Adaptive mesh refinement is a technique for enriching the mesh during a simulation based on metrics for error, impact on important parameters, or location of important flow features. This can offload from the user some of the difficult and ambiguous decisions necessary when discretizing the domain. This work explores the implementation of adaptive mesh refinement in an implicit, unstructured, finite-volume solver. Consideration is made for applying modern computational techniques in the presence of hanging nodes and refined cells. The approach is developed to be independent of the flow solver in order to provide a path for augmenting existing codes. It is designed to be applicable for unsteady simulations and refinement and coarsening of the grid does not impact the conservatism of the underlying numerics. The effect on high-order numerical fluxes of fourth- and sixth-order are explored. Provided the criteria for refinement is appropriately selected, solutions obtained using adapted meshes have no additional error when compared to results obtained on traditional, unadapted meshes. In order to leverage large-scale computational resources common today, the methods are parallelized using MPI. Parallel performance is considered for several test problems in order to assess scalability of both adapted and unadapted grids. Dynamic repartitioning of the mesh during refinement is crucial for load balancing an evolving grid. Development of the methods outlined here depend on a dual-memory approach that is described in detail. Validation of the solver developed here against a number of motivating problems shows favorable
Kou, Jisheng
2017-09-30
Capillary pressure can significantly affect the phase properties and flow of liquid-gas fluids in porous media, and thus, the phase equilibrium calculation incorporating capillary pressure is crucial to simulate such problems accurately. Recently, the phase equilibrium calculation at specified moles, volume and temperature (NVT-flash) becomes an attractive issue. In this paper, capillarity is incorporated into the phase equilibrium calculation at specified moles, volume and temperature. A dynamical model for such problem is developed for the first time by using the laws of thermodynamics and Onsager\\'s reciprocal principle. This model consists of the evolutionary equations for moles and volume, and it can characterize the evolutionary process from a non-equilibrium state to an equilibrium state in the presence of capillarity effect at specified moles, volume and temperature. The phase equilibrium equations are naturally derived. To simulate the proposed dynamical model efficiently, we adopt the convex-concave splitting of the total Helmholtz energy, and propose a thermodynamically stable numerical algorithm, which is proved to preserve the second law of thermodynamics at the discrete level. Using the thermodynamical relations, we derive a phase stability condition with capillarity effect at specified moles, volume and temperature. Moreover, we propose a stable numerical algorithm for the phase stability testing, which can provide the feasible initial conditions. The performance of the proposed methods in predicting phase properties under capillarity effect is demonstrated on various cases of pure substance and mixture systems.
Energy Technology Data Exchange (ETDEWEB)
Mehndiratta, Amit [Massachusetts General Hospital, Department of Radiology, Harvard Medical School, Boston, MA (United States); University of Oxford, Institute of Biomedical Engineering and Keble College, Oxford (United Kingdom); Indian Institute of Technology Delhi and All India Institute of Medical Science, Centre for Biomedical Engineering, New Delhi (India); Rabinov, James D. [Massachusetts General Hospital, Interventional Neuroradiology, Harvard Medical School, Boston, MA (United States); Grasruck, Michael [Siemens Medical Solutions, Forchheim (Germany); Liao, Eric C. [Massachusetts General Hospital, Department of Plastic and Reconstructive Surgery and Center for Regenerative Medicine, Harvard Medical School, Boston, MA (United States); Crandell, David [Spaulding Rehabilitation Hospital, Department of Physical Medicine and Rehabilitation, Harvard Medical School, Charlestown, MA (United States); Gupta, Rajiv [Massachusetts General Hospital, Department of Radiology, Harvard Medical School, Boston, MA (United States)
2015-07-15
This paper evaluates a prototype flat-panel volume CT (fpVCT) for dynamic in vivo imaging in a variety of neurovascular and lower limb applications. Dynamic CTA was performed on 12 patients (neuro = 8, lower limb = 4) using an fpVCT with 120 kVp, 50 mA, rotation time varying from 8 to 19 s, and field of view of 25 x 25 x 18 cm{sup 3}. Four-dimensional data sets (i.e. 3D images over time) were reconstructed and reviewed. Dynamic CTA demonstrated sufficient spatio-temporal resolution to elucidate first-pass and recirculation dynamics of contrast bolus through neurovasclar pathologies and phasic blood flow though lower-limb vasculature and grafts. The high spatial resolution of fpVCT resulted in reduced partial volume and metal beam-hardening artefacts. This facilitated assessment of vascular lumen in the presence of calcified plaque and evaluation of fractures, especially in the presence of fixation hardware. Evaluation of arteriovenous malformation using dynamic fpVCT angiography was of limited utility. Dynamic CTA using fpVCT can visualize time-varying phenomena in neuro and lower limb vascular applications and has sufficient diagnostic imaging quality to evaluate a number of pathologies affecting these regions. (orig.)
Daniele, C. J.; Lorenzo, C. F.
1979-01-01
Lumped volume dynamic equations are derived using an energy-state formulation. This technique requires that kinetic and potential energy state functions be written for the physical system being investigated. To account for losses in the system, a Rayleigh dissipation function is also formed. Using these functions, a Lagrangian is formed and using Lagrange's equation, the equations of motion for the system are derived. The results of the application of this technique to a lumped volume are used to derive a model for the free-piston Stirling engine. The model was simplified and programmed on an analog computer. Results are given comparing the model response with experimental data.
Bodley, C. S.; Devers, D. A.; Park, C. A.
1975-01-01
A theoretical development and associated digital computer program system is presented. The dynamic system (spacecraft) is modeled as an assembly of rigid and/or flexible bodies not necessarily in a topological tree configuration. The computer program system may be used to investigate total system dynamic characteristics including interaction effects between rigid and/or flexible bodies, control systems, and a wide range of environmental loadings. Additionally, the program system may be used for design of attitude control systems and for evaluation of total dynamic system performance including time domain response and frequency domain stability analyses. Volume 1 presents the theoretical developments including a description of the physical system, the equations of dynamic equilibrium, discussion of kinematics and system topology, a complete treatment of momentum wheel coupling, and a discussion of gravity gradient and environmental effects. Volume 2, is a program users' guide and includes a description of the overall digital program code, individual subroutines and a description of required program input and generated program output. Volume 3 presents the results of selected demonstration problems that illustrate all program system capabilities.
Gritti, Fabrice; Kazakevich, Yuri; Guiochon, Georges
2007-08-17
The hold-up volumes, V(M) of two series of RPLC adsorbents were measured using three different approaches. The first method is based on the difference between the volumes of the empty column tube (150x4.6mm) and of the material packed inside the column. It is considered as giving the correct value of V(M). This method combines the results of the BET characterization of the adsorbent before packing (giving the specific pore volume), of carbon element analysis (giving the mass fraction of silica and alkyl bonded chains), of Helium pycnometry (providing silica density), and of inverse size exclusion chromatography (ISEC) performed on the packed column (yielding the interparticle volume). The second method is static pycnometry, which consists in weighing the masses of the chromatographic column filled with two distinct solvents of different densities. The last method is based on the thermodynamic definition of the hold-up volume and uses the dynamic minor disturbance method (MDM) with binary eluents. The experimental results of these three non-destructive methods are compared. They exhibit significant, systematic differences. Pycnometry underestimates V(M) by a few percent for adsorbents having a high carbon content. The results of the MDM method depend strongly on the choice of the binary solution used and may underestimate or overestimate V(M). The hold-up volume V(M) of the RPLC adsorbents tested is best measured by the MDM method using a mixture of ethanol and water.
Self-oscillations of a third order PLL in periodic and chaotic mode and its tracking in a slave PLL
Sarkar, B. C.; Chakraborty, S.
2014-03-01
The dynamics of a third order phase locked loop (PLL) with a resonant low pass filter (LPF) has been studied numerically in the parameter space of the system. The range of stable synchronous operating zone of the PLL, expressed in terms of system and signal parameters, is estimated. The obtained results are in agreement with the analytically predicted results in the literature. The PLL dynamics in the unstable region is found to have a sequence of period doubling bifurcation and chaos. In the master-slave mode of operation of two 3rd order PLLs, the slave PLL can track the periodic as well as chaotic dynamics of the master PLL for a narrow range of effective frequency offset when other design parameters are within the stable zone as predicted for an isolated PLL. The synchronization of the master and slave PLLs in this condition is proved to be a generalized one using the auxiliary slave system approach. Experimental observations on prototype hardware circuits for an isolated PLL and for a master-slave PLL arrangement are also given.
Lian, Ming; Zhao, Xiao; Wang, Hong; Chen, Lianhua; Li, Shitong
2016-12-30
Laparoscopic operations have become longer and more complex and applied to a broader patient population in the last decades. Prolonged gynecological laparoscopic surgeries require prolonged pneumoperitoneum and Trendelenburg position, which can influence respiratory dynamics and other measurements of pulmonary function. We investigated the differences between volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV) and tried to determine the more efficient ventilation mode during prolonged pneumoperitoneum in gynecological laparoscopy. Twenty-six patients scheduled for laparoscopic radical hysterectomy combined with or without laparoscopic pelvic lymphadenectomy were randomly allocated to be ventilated by either VCV or PCV. Standard anesthesic management and laparoscopic procedures were performed. Measurements of respiratory and hemodynamic dynamics were obtained after induction of anesthesia, at 10, 30, 60, and 120 min after establishing pneumoperitoneum, and at 10 min after return to supine lithotomy position and removal of carbon dioxide. The logistic regression model was applied to predict the corresponding critical value of duration of pneumoperitoneum when the Ppeak was higher than 40 cmH2O. Prolonged pneumoperitoneum and Trendelenburg position produced significant and clinically relevant changes in dynamic compliance and respiratory mechanics in anesthetized patients under PCV and VCV ventilation. Patients under PCV ventilation had a similar increase of dead space/tidal volume ratio, but had a lower Ppeak increase compared with those under VCV ventilation. The critical value of duration of pneumoperitoneum was predicted to be 355 min under VCV ventilation, corresponding to the risk of Ppeak higher than 40 cmH2O. Both VCV and PCV can be safely applied to prolonged gynecological laparoscopic surgery. However, PCV may become the better choice of ventilation after ruling out of other reasons for Ppeak increasing.
Hurlimann Ziegler, Marcel; Abancó, Clàudia; Moya Sánchez, José
2014-01-01
The sophisticated monitoring system installed in the Rebaixader catchment incorporates a total of 6 different stations: four stations recording information on the initiation mechanisms (two meteorological stations and two infiltration stations), and two stations focussing on the debris flow detection and the dynamic behaviour of the flows. Between August 2009 and August 2013, seven debris flows and seventeen debris floods were detected. The volumes of the debris flows ranged from 2,100 to 16,...
Directory of Open Access Journals (Sweden)
Ertugrul Gelen
2012-12-01
Full Text Available The purpose of this study was to compare the acute effects of static stretching; dynamic exercises and high volume upper extremity plyometric activity on tennis serve performance. Twenty-six elite young tennis players (15.1 ± 4.2 years, 167.9 ± 5.8 cm and 61.6 ± 8.1 kg performed 4 different warm-up (WU routines in a random order on non-consecutive days. The WU methods consisted of traditional WU (jogging, rally and serve practice (TRAD; traditional WU and static stretching (TRSS; traditional WU and dynamic exercise (TRDE; and traditional WU and high volume upper extremity plyometric activity (TRPLYP. Following each WU session, subjects were tested on a tennis serve ball speed test. TRAD, TRSS, TRDE and TRPLYO were compared by repeated measurement analyses of variance and post-hoc comparisons. In this study a 1 to 3 percent increase in tennis serve ball speed was recorded in TRDE and TRPLYO when compared to TRAD (p 0.05. ICCs for ball speed showed strong reliability (0.82 to 0.93 for the ball speed measurements.The results of this study indicate that dynamic and high volume upper extremity plyometric WU activities are likely beneficial to serve speed of elite junior tennis players.
Directory of Open Access Journals (Sweden)
Martin Lundsgaard Hansen
2016-02-01
Full Text Available The purpose of this study was to assess inter- and intra-observer reproducibility of three different analytic methods to evaluate quantitative dynamic contrast-enhanced computed tomography (DCE-CT measures from gastroesophageal junctional cancer. Twenty-five DCE-CT studies with gastroesophageal junction cancer were selected from a previous longitudinal study. Three radiologists independently reviewed all scans, and one repeated the analysis eight months later for intraobserver analysis. Review of the scans consisted of three analysis methods: (I Four, fixed small sized regions of interest (2-dimensional (2D fixed ROIs placed in the tumor periphery, (II 2-dimensional regions of interest (2D-ROI along the tumor border in the tumor center, and (III 3-dimensional volumes of interest (3D-VOI containing the entire tumor volume. Arterial flow, blood volume and permeability (ktrans were recorded for each observation. Inter- and intra-observer variability were assessed by Intraclass Correlation Coefficient (ICC and Bland-Altman statistics. Interobserver ICC was excellent for arterial flow (0.88, for blood volume (0.89 and for permeability (0.91 with 3D-VOI analysis. The 95% limits of agreement were narrower for 3D analysis compared to 2D analysis. Three-dimensional volume DCE-CT analysis of gastroesophageal junction cancer provides higher inter- and intra-observer reproducibility with narrower limits of agreement between readers compared to 2D analysis.
Lundsgaard Hansen, Martin; Fallentin, Eva; Axelsen, Thomas; Lauridsen, Carsten; Norling, Rikke; Svendsen, Lars Bo; Nielsen, Michael Bachmann
2016-02-01
The purpose of this study was to assess inter- and intra-observer reproducibility of three different analytic methods to evaluate quantitative dynamic contrast-enhanced computed tomography (DCE-CT) measures from gastroesophageal junctional cancer. Twenty-five DCE-CT studies with gastroesophageal junction cancer were selected from a previous longitudinal study. Three radiologists independently reviewed all scans, and one repeated the analysis eight months later for intraobserver analysis. Review of the scans consisted of three analysis methods: (I) Four, fixed small sized regions of interest (2-dimensional (2D) fixed ROIs) placed in the tumor periphery, (II) 2-dimensional regions of interest (2D-ROI) along the tumor border in the tumor center, and (III) 3-dimensional volumes of interest (3D-VOI) containing the entire tumor volume. Arterial flow, blood volume and permeability (k(trans)) were recorded for each observation. Inter- and intra-observer variability were assessed by Intraclass Correlation Coefficient (ICC) and Bland-Altman statistics. Interobserver ICC was excellent for arterial flow (0.88), for blood volume (0.89) and for permeability (0.91) with 3D-VOI analysis. The 95% limits of agreement were narrower for 3D analysis compared to 2D analysis. Three-dimensional volume DCE-CT analysis of gastroesophageal junction cancer provides higher inter- and intra-observer reproducibility with narrower limits of agreement between readers compared to 2D analysis.
A Fully Integrated 2:1 Self-Oscillating Switched-Capacitor DC–DC Converter in 28 nm UTBB FD-SOI
Directory of Open Access Journals (Sweden)
Matthew Turnquist
2016-09-01
Full Text Available The importance of energy-constrained processors continues to grow especially for ultra-portable sensor-based platforms for the Internet-of-Things (IoT. Processors for these IoT applications primarily operate at near-threshold (NT voltages and have multiple power modes. Achieving high conversion efficiency within the DC–DC converter that supplies these processors is critical since energy consumption of the DC–DC/processor system is proportional to the DC–DC converter efficiency. The DC–DC converter must maintain high efficiency over a large load range generated from the multiple power modes of the processor. This paper presents a fully integrated step-down self-oscillating switched-capacitor DC–DC converter that is capable of meeting these challenges. The area of the converter is 0.0104 mm2 and is designed in 28 nm ultra-thin body and buried oxide fully-depleted SOI (UTBB FD-SOI. Back-gate biasing within FD-SOI is utilized to increase the load power range of the converter. With an input of 1 V and output of 460 mV, measurements of the converter show a minimum efficiency of 75% for 79 nW to 200 µW loads. Measurements with an off-chip NT processor load show efficiency up to 86%. The converter’s large load power range and high efficiency make it an excellent fit for energy-constrained processors.
Dynamic Regulation of Cell Volume and Extracellular ATP of Human Erythrocytes
Leal Denis, M. Florencia; Alvarez, H. Ariel; Lauri, Natalia; Alvarez, Cora L.; Chara, Osvaldo; Schwarzbaum, Pablo J.
2016-01-01
Introduction The peptide mastoparan 7 (MST7) triggered in human erythrocytes (rbcs) the release of ATP and swelling. Since swelling is a well-known inducer of ATP release, and extracellular (ATPe), interacting with P (purinergic) receptors, can affect cell volume (Vr), we explored the dynamic regulation between Vr and ATPe. Methods and Treatments We made a quantitative assessment of MST7-dependent kinetics of Vr and of [ATPe], both in the absence and presence of blockers of ATP efflux, swelling and P receptors. Results In rbcs 10 μM MST7 promoted acute, strongly correlated changes in [ATPe] and Vr. Whereas MST7 induced increases of 10% in Vr and 190 nM in [ATPe], blocking swelling in a hyperosmotic medium + MST7 reduced [ATPe] by 40%. Pre-incubation of rbcs with 10 μM of either carbenoxolone or probenecid, two inhibitors of the ATP conduit pannexin 1, reduced [ATPe] by 40–50% and swelling by 40–60%, while in the presence of 80 U/mL apyrase, an ATPe scavenger, cell swelling was prevented. While exposure to 10 μM NF110, a blocker of ATP-P2X receptors mediating sodium influx, reduced [ATPe] by 48%, and swelling by 80%, incubation of cells in sodium free medium reduced swelling by 92%. Analysis and Discussion Results were analyzed by means of a mathematical model where ATPe kinetics and Vr kinetics were mutually regulated. Model dependent fit to experimental data showed that, upon MST7 exposure, ATP efflux required a fast 1960-fold increase of ATP permeability, mediated by two kinetically different conduits, both of which were activated by swelling and inactivated by time. Both experimental and theoretical results suggest that, following MST7 exposure, ATP is released via two conduits, one of which is mediated by pannexin 1. The accumulated ATPe activates P2X receptors, followed by sodium influx, resulting in cell swelling, which in turn further activates ATP release. Thus swelling and P2X receptors constitute essential components of a positive feedback loop
Dynamic Regulation of Cell Volume and Extracellular ATP of Human Erythrocytes.
Directory of Open Access Journals (Sweden)
M Florencia Leal Denis
Full Text Available The peptide mastoparan 7 (MST7 triggered in human erythrocytes (rbcs the release of ATP and swelling. Since swelling is a well-known inducer of ATP release, and extracellular (ATPe, interacting with P (purinergic receptors, can affect cell volume (Vr, we explored the dynamic regulation between Vr and ATPe.We made a quantitative assessment of MST7-dependent kinetics of Vr and of [ATPe], both in the absence and presence of blockers of ATP efflux, swelling and P receptors.In rbcs 10 μM MST7 promoted acute, strongly correlated changes in [ATPe] and Vr. Whereas MST7 induced increases of 10% in Vr and 190 nM in [ATPe], blocking swelling in a hyperosmotic medium + MST7 reduced [ATPe] by 40%. Pre-incubation of rbcs with 10 μM of either carbenoxolone or probenecid, two inhibitors of the ATP conduit pannexin 1, reduced [ATPe] by 40-50% and swelling by 40-60%, while in the presence of 80 U/mL apyrase, an ATPe scavenger, cell swelling was prevented. While exposure to 10 μM NF110, a blocker of ATP-P2X receptors mediating sodium influx, reduced [ATPe] by 48%, and swelling by 80%, incubation of cells in sodium free medium reduced swelling by 92%.Results were analyzed by means of a mathematical model where ATPe kinetics and Vr kinetics were mutually regulated. Model dependent fit to experimental data showed that, upon MST7 exposure, ATP efflux required a fast 1960-fold increase of ATP permeability, mediated by two kinetically different conduits, both of which were activated by swelling and inactivated by time. Both experimental and theoretical results suggest that, following MST7 exposure, ATP is released via two conduits, one of which is mediated by pannexin 1. The accumulated ATPe activates P2X receptors, followed by sodium influx, resulting in cell swelling, which in turn further activates ATP release. Thus swelling and P2X receptors constitute essential components of a positive feedback loop underlying ATP-induced ATP release of rbcs.
Jelinek, Herbert F; Karmakar, C; Kiviniemi, A M; Hautala, A J; Tulppo, M P; Mäkikallio, T H; Huikuri, H V; Khandoker, A H; Palaniswami, M
2015-10-01
Increased risk of arrhythmic events occurs at certain times during the circadian cycle with the highest risk being in the second and fourth quarter of the day. Exercise improves treatment outcome in individuals with cardiovascular disease. How different exercise protocols affect the circadian rhythm and the associated decrease in adverse cardiovascular risk over the circadian cycle has not been shown. Fifty sedentary male participants were randomized into an 8-week high volume and moderate volume training and a control group. Heart rate was recorded using Polar Electronics and investigated with Cosinor analysis and by Poincaré plot derived features of SD1, SD2 and the complex correlation measure (CCM) at 1-h intervals over the 24-h period. Moderate exercise significantly increased vagal modulation and the temporal dynamics of the heart rate in the second quarter of the circadian cycle (p = 0.004 and p = 0.007 respectively). High volume exercise had a similar effect on vagal output (p = 0.003) and temporal dynamics (p = 0.003). Cosinor analysis confirms that the circadian heart rate displays a shift in the acrophage following moderate and high volume exercise from before waking (1st quarter) to after waking (2nd quarter of day). Our results suggest that exercise shifts vagal influence and increases temporal dynamics of the heart rate to the 2nd quarter of the day and suggest that this may be the underlying physiological change leading to a decrease in adverse arrhythmic events during this otherwise high-risk period.
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Chao Chen
Full Text Available OBJECTIVE: To investigate microcirculatory differences between pathologic types of kidney tumor using 320-slice dynamic volume CT perfusion. METHODS: Perfusion imaging with 320-slice dynamic volume CT was prospectively performed in 85 patients with pathologically proven clear cell renal cell carcinoma (RCC (n = 66, papillary RCC (n = 7, chromophobe RCC (n = 5, angiomyolipoma (AML with minimal fat (n = 7, or RCC (n = 78. Equivalent blood volume (Equiv BV, permeability surface-area product (PS; clearance/unit volume = permeability, and blood flow (BF of tumor and normal renal cortex were measured and analyzed. Effective radiation dose was calculated. RESULTS: There was a significant difference in all three parameters between tumor and normal renal cortex (P<0.001. Equiv BV was significantly different between RCC and AML with minimal fat (P = 0.038 and between clear cell RCC and AML with minimal fat (P<0.001. Mean Equiv BV and BF were significantly higher in clear cell RCC than in papillary RCC (P<0.001 for both and mean Equiv BV was higher in clear cell RCC than in chromophobe RCC (P<0.001. The effective radiation dose of the CT perfusion protocol was 18.5 mSv. CONCLUSION: Perfusion imaging using 320-slice dynamic volume CT can be used to evaluate hemodynamic features of the whole kidney and kidney tumors, which may be useful in the differential diagnosis of these four pathologic types of kidney tumor.
Ratas, Irmantas; Pyragas, Kestutis
2016-09-01
We analyze the dynamics of a large network of coupled quadratic integrate-and-fire neurons, which represent the canonical model for class I neurons near the spiking threshold. The network is heterogeneous in that it includes both inherently spiking and excitable neurons. The coupling is global via synapses that take into account the finite width of synaptic pulses. Using a recently developed reduction method based on the Lorentzian ansatz, we derive a closed system of equations for the neuron's firing rate and the mean membrane potential, which are exact in the infinite-size limit. The bifurcation analysis of the reduced equations reveals a rich scenario of asymptotic behavior, the most interesting of which is the macroscopic limit-cycle oscillations. It is shown that the finite width of synaptic pulses is a necessary condition for the existence of such oscillations. The robustness of the oscillations against aging damage, which transforms spiking neurons into nonspiking neurons, is analyzed. The validity of the reduced equations is confirmed by comparing their solutions with the solutions of microscopic equations for the finite-size networks.
Energy Technology Data Exchange (ETDEWEB)
Takara, L.S.; Cunha, T.M.; Barbosa, P.; Rodrigues, M.K.; Oliveira, M.F.; Nery, L.E. [Setor de Função Pulmonar e Fisiologia Clínica do Exercício, Disciplina de Pneumologia, Departamento de Medicina, Universidade Federal de São Paulo, São Paulo, SP (Brazil); Neder, J.A. [Setor de Função Pulmonar e Fisiologia Clínica do Exercício, Disciplina de Pneumologia, Departamento de Medicina, Universidade Federal de São Paulo, São Paulo, SP (Brazil); Division of Respiratory and Critical Care Medicine, Department of Medicine, Queen' s University, Kingston, ON (Canada)
2012-10-15
This study evaluated the dynamic behavior of total and compartmental chest wall volumes [(V{sub CW}) = rib cage (V{sub RC}) + abdomen (V{sub AB})] as measured breath-by-breath by optoelectronic plethysmography during constant-load exercise in patients with stable chronic obstructive pulmonary disease. Thirty males (GOLD stages II-III) underwent a cardiopulmonary exercise test to the limit of tolerance (Tlim) at 75% of peak work rate on an electronically braked cycle ergometer. Exercise-induced dynamic hyperinflation was considered to be present when end-expiratory (EE) V{sub CW} increased in relation to resting values. There was a noticeable heterogeneity in the patterns of V{sub CW} regulation as EEV{sub CW} increased non-linearly in 17/30 “hyperinflators” and decreased in 13/30 “non-hyperinflators” (P < 0.05). EEV{sub AB} decreased slightly in 8 of the “hyperinflators”, thereby reducing and slowing the rate of increase in end-inspiratory (EI) V{sub CW} (P < 0.05). In contrast, decreases in EEV{sub CW} in the “non-hyperinflators” were due to the combination of stable EEV{sub RC} with marked reductions in EEV{sub AB}. These patients showed lower EIV{sub CW} and end-exercise dyspnea scores but longer Tlim than their counterparts (P < 0.05). Dyspnea increased and Tlim decreased non-linearly with a faster rate of increase in EIV{sub CW} regardless of the presence or absence of dynamic hyperinflation (P < 0.001). However, no significant between-group differences were observed in metabolic, pulmonary gas exchange and cardiovascular responses to exercise. Chest wall volumes are continuously regulated during exercise in order to postpone (or even avoid) their migration to higher operating volumes in patients with COPD, a dynamic process that is strongly dependent on the behavior of the abdominal compartment.
Directory of Open Access Journals (Sweden)
L.S. Takara
2012-12-01
Full Text Available This study evaluated the dynamic behavior of total and compartmental chest wall volumes [(V CW = rib cage (V RC + abdomen (V AB] as measured breath-by-breath by optoelectronic plethysmography during constant-load exercise in patients with stable chronic obstructive pulmonary disease. Thirty males (GOLD stages II-III underwent a cardiopulmonary exercise test to the limit of tolerance (Tlim at 75% of peak work rate on an electronically braked cycle ergometer. Exercise-induced dynamic hyperinflation was considered to be present when end-expiratory (EE V CW increased in relation to resting values. There was a noticeable heterogeneity in the patterns of V CW regulation as EEV CW increased non-linearly in 17/30 "hyperinflators" and decreased in 13/30 "non-hyperinflators" (P < 0.05. EEV AB decreased slightly in 8 of the "hyperinflators", thereby reducing and slowing the rate of increase in end-inspiratory (EI V CW (P < 0.05. In contrast, decreases in EEV CW in the "non-hyperinflators" were due to the combination of stable EEV RC with marked reductions in EEV AB. These patients showed lower EIV CW and end-exercise dyspnea scores but longer Tlim than their counterparts (P < 0.05. Dyspnea increased and Tlim decreased non-linearly with a faster rate of increase in EIV CW regardless of the presence or absence of dynamic hyperinflation (P < 0.001. However, no significant between-group differences were observed in metabolic, pulmonary gas exchange and cardiovascular responses to exercise. Chest wall volumes are continuously regulated during exercise in order to postpone (or even avoid their migration to higher operating volumes in patients with COPD, a dynamic process that is strongly dependent on the behavior of the abdominal compartment.
Joint dynamics of prices and trading volume on the Polish stock market:
Henryk Gurgul; Pawel Majdosz; Roland Mestel
2005-01-01
This paper concerns the relationship between stock returns and trading volume. We use daily stock data of the Polish companies included in the WIG20 segment (the twenty most liquid companies quoted on the primary market of the Warsaw Stock Exchange). The sample covers the period from January 1995 to April 2005. We find that there is no empirical support for a relationship between stock return levels and trading volume. On the other hand, our calculations provide evidence for a significant con...
Pretorius, P. H.; King, Michael A.; Tsui, Benjamin M.; LaCroix, Karen; Xia, Weishi
1998-07-01
This manuscript documents the alteration of the heart model of the MCAT phantom to better represent cardiac motion. The objective of the inclusion of motion was to develop a digital simulation of the heart such that the impact of cardiac motion on single photon emission computed tomography (SPECT) imaging could be assessed and methods of quantitating cardiac function could be investigated. The motion of the dynamic MCAT's heart is modeled by a 128 time frame volume curve. Eight time frames are averaged together to obtain a gated perfusion acquisition of 16 time frames and ensure motion within every time frame. The position of the MCAT heart was changed during contraction to rotate back and forth around the long axis through the center of the left ventricle (LV) using the end systolic time frame as turning point. Simple respiratory motion was also introduced by changing the orientation of the heart model in a 2 dimensional (2D) plane with every time frame. The averaging effect of respiratory motion in a specific time frame was modeled by randomly selecting multiple heart locations between two extreme orientations. Non-gated perfusion phantoms were also generated by averaging over all time frames. Maximal chamber volumes were selected to fit a profile of a normal healthy person. These volumes were changed during contraction of the ventricles such that the increase in volume in the atria compensated for the decrease in volume in the ventricles. The myocardium were modeled to represent shortening of muscle fibers during contraction with the base of the ventricles moving towards a static apex. The apical region was modeled with moderate wall thinning present while myocardial mass was conserved. To test the applicability of the dynamic heart model, myocardial wall thickening was measured using maximum counts and full width half maximum measurements, and compared with published trends. An analytical 3D projector, with attenuation and detector response included, was used
Energy Technology Data Exchange (ETDEWEB)
Taylor, L.L.; Wilson, J.R. (INEEL); Sanchez, L.C.; Aguilar, R.; Trellue, H.R.; Cochrane, K. (SNL); Rath, J.S. (New Mexico Engineering Research Institute)
1998-10-01
The United States Department of Energy Office of Environmental Management's (DOE/EM's) National Spent Nuclear Fuel Program (NSNFP), through a collaboration between Sandia National Laboratories (SNL) and Idaho National Engineering and Environmental Laboratory (INEEL), is conducting a systematic Nuclear Dynamics Consequence Analysis (NDCA) of the disposal of SNFs in an underground geologic repository sited in unsaturated tuff. This analysis is intended to provide interim guidance to the DOE for the management of the SNF while they prepare for final compliance evaluation. This report presents results from a Nuclear Dynamics Consequence Analysis (NDCA) that examined the potential consequences and risks of criticality during the long-term disposal of spent nuclear fuel owned by DOE-EM. This analysis investigated the potential of post-closure criticality, the consequences of a criticality excursion, and the probability frequency for post-closure criticality. The results of the NDCA are intended to provide the DOE-EM with a technical basis for measuring risk which can be used for screening arguments to eliminate post-closure criticality FEPs (features, events and processes) from consideration in the compliance assessment because of either low probability or low consequences. This report is composed of an executive summary (Volume 1), the methodology and results of the NDCA (Volume 2), and the applicable appendices (Volume 3).
LoMauro, Antonella; Cesareo, Ambra; Agosti, Fiorenza; Tringali, Gabriella; Salvadego, Desy; Grassi, Bruno; Sartorio, Alessandro; Aliverti, Andrea
2016-06-01
The objective of this study was to characterize static and dynamic thoraco-abdominal volumes in obese adolescents and to test the effects of a 3-week multidisciplinary body weight reduction program (MBWRP), entailing an energy-restricted diet, psychological and nutritional counseling, aerobic physical activity, and respiratory muscle endurance training (RMET), on these parameters. Total chest wall (VCW), pulmonary rib cage (VRC,p), abdominal rib cage (VRC,a), and abdominal (VAB) volumes were measured on 11 male adolescents (Tanner stage: 3-5; BMI standard deviation score: >2; age: 15.9 ± 1.3 years; percent body fat: 38.4%) during rest, inspiratory capacity (IC) maneuver, and incremental exercise on a cycle ergometer at baseline and after 3 weeks of MBWRP. At baseline, the progressive increase in tidal volume was achieved by an increase in end-inspiratory VCW (p obese adolescents adopt a thoraco-abdominal operational pattern characterized by abdominal rib cage hyperinflation as a form of lung recruitment during incremental cycle exercise. Additionally, a short period of MBWRP including RMET is associated with improved exercise performance, lung and chest wall volume recruitment, unloading of respiratory muscles, and reduced dyspnea.
Lossless compression of very large volume data with fast dynamic access
Zhao, Rongkai; Tao, Tao; Gabriel, Michael; Belford, Geneva
2002-09-01
The volumetric data set is important in many scientific and biomedical fields. Since such sets may be extremely large, a compression method is critical to store and transmit them. To achieve a high compression rate, most of the existing volume compression methods are lossy, which is usually unacceptable in biomedical applications. We developed a new context-based non-linear prediction method to preprocess the volume data set in order to effectively lower the prediction entropy. The prediction error is further encoded using Huffman code. Unlike the conventional methods, the volume is divided into cubical blocks to take advantage of the data's spatial locality. Instead of building one Huffman tree for each block, we developed a novel binning algorithm that build a Huffman tree for each group (bin) of blocks. Combining all the effects above, we achieved an excellent compression rate compared to other lossless volume compression methods. In addition, an auxiliary data structure, Scalable Hyperspace File (SHSF) is used to index the huge volume so that we can obtain many other benefits including parallel construction, on-the-fly accessing of compressed data without global decompression, fast previewing, efficient background compressing, and scalability etc.
Energy Technology Data Exchange (ETDEWEB)
Nichols, B. D.; Mueller, C.; Necker, G. A.; Travis, J. R.; Spore, J. W.; Lam, K. L.; Royl, P.; Wilson, T. L.
1998-10-01
Los Alamos National Laboratory (LANL) and Forschungszentrum Karlsruhe (FzK) are developing GASFLOW, a three-dimensional (3D) fluid dynamics field code as a best-estimate tool to characterize local phenomena within a flow field. Examples of 3D phenomena include circulation patterns; flow stratification; hydrogen distribution mixing and stratification; combustion and flame propagation; effects of noncondensable gas distribution on local condensation and evaporation; and aerosol entrainment, transport, and deposition. An analysis with GASFLOW will result in a prediction of the gas composition and discrete particle distribution in space and time throughout the facility and the resulting pressure and temperature loadings on the walls and internal structures with or without combustion. A major application of GASFLOW is for predicting the transport, mixing, and combustion of hydrogen and other gases in nuclear reactor containment and other facilities. It has been applied to situations involving transporting and distributing combustible gas mixtures. It has been used to study gas dynamic behavior in low-speed, buoyancy-driven flows, as well as sonic flows or diffusion dominated flows; and during chemically reacting flows, including deflagrations. The effects of controlling such mixtures by safety systems can be analyzed. The code version described in this manual is designated GASFLOW 2.1, which combines previous versions of the United States Nuclear Regulatory Commission code HMS (for Hydrogen Mixing Studies) and the Department of Energy and FzK versions of GASFLOW. The code was written in standard Fortran 90. This manual comprises three volumes. Volume I describes the governing physical equations and computational model. Volume II describes how to use the code to set up a model geometry, specify gas species and material properties, define initial and boundary conditions, and specify different outputs, especially graphical displays. Sample problems are included. Volume III
Directory of Open Access Journals (Sweden)
Daniel Ruijters
2008-09-01
Full Text Available The generation of multiview stereoscopic images of large volume rendered data demands an enormous amount of calculations. We propose a method for hardware accelerated volume rendering of medical data sets to multiview lenticular displays, offering interactive manipulation throughout. The method is based on buffering GPU-accelerated direct volume rendered visualizations of the individual views from their respective focal spot positions, and composing the output signal for the multiview lenticular screen in a second pass. This compositing phase is facilitated by the fact that the view assignment per subpixel is static, and therefore can be precomputed. We decoupled the resolution of the individual views from the resolution of the composited signal, and adjust the resolution on-the-fly, depending on the available processing resources, in order to maintain interactive refresh rates. The optimal resolution for the volume rendered views is determined by means of an analysis of the lattice of the output signal for the lenticular screen in the Fourier domain.
Dynamic cortical gray matter volume changes after botulinum toxin in cervical dystonia
Delnooz, C.C.S.; Pasman, J.W.; Warrenburg, B.P.C. van de
2015-01-01
Previous electrophysiological and functional imaging studies in focal dystonia have reported on cerebral reorganization after botulinum toxin (BoNT) injections. With the exception of microstructural changes, alterations in gray matter volume after BoNT have not been explored. In this study, we
DEFF Research Database (Denmark)
Damkjær, Jesper; Erleben, Kenny
2009-01-01
hierarchies. Our approach makes it possible to perform non-convex object versus non-convex object collision on the GPU, using tandem traversals of bounding volume hierarchies. Prior work only supports single traversals on GPUs. We introduce a blocked hierarchy data structure, using imaginary nodes...
METHODS OF CHAOTIC DYNAMICS IN SCHEMES OF RESEARCHES FEASIBILITY INTERNALS OF CAR TRAFFIC VOLUMES
National Research Council Canada - National Science Library
H. A. Kramarenko; A. V. Nechay; V. V. Skalozub
2011-01-01
The possibilities of chaotic dynamics methods applied to the topical analysis and forecasting problems of economic and technological properties of wagon streams represented by the related time series are studied...
Experimental Modal Analysis and Dynamic Component Synthesis. Volume 1. Summary of Technical Work
1987-12-01
Rades. M., "Identification of the Dynamic Characteristics of a Simple System with Quadratic Damping," Serie de Mecanique Appliquee. 28 (4), 1983, pp...Measurement and Analysis Requirements," SAE Paper Number 751066 1975, 17 pp. [261 Prony, R. "Essai Experimental et Analytique sur les Lois de [a...of the Dynamic Characteristics of a Simple System with Quadratic Damping, Serie de Mecanique Appliquee, Vol. 28, Num. 4, 1983, pp. 439-446. 11391
DIGITAL SELF-OSCILLATING MODULATOR
DEFF Research Database (Denmark)
2007-01-01
the digi- tal output from the feedback block (18) and the digital reference signal (Vref). The first output is in digital form fed back to the feedback block (18). Provided that the transfer function (MFW) of the forward block (12) is formed by a plurality of integrators, the transfer function (MFB...
Pang, Baojun; Wang, Liwen; Yang, Zhenqi; Chi, Runqiang
2009-06-01
Dynamic strain-stress curves of reactive powder concrete under high strain rate (10/s-100/s) were determined by improved split Hopkinson pressure bar (SHPB) system. A plumbum pulse shaper was used to ensure the symmetrical stress in the specimens before fracture and avoid the fluctuation of test data due to input shaky stress pulse. A time modified method was induced for data processing in order to get accurate SHPB results. The results of experiment showed after high temperature burnt, different volume rate (0.0%, 0.5%, 1.0%, 1.5%) steel-fiber reinforced reactive power concrete had the same changing tendency of residual mechanics behaviors, e.g. after 400 centigrade burnt, the residual compression strength was about 70% of material strength without burnt under 100/s. After 800 centigrade burnt, the compression strength is about 30% under 100/s while the deformation ability increased. At meanwhile, steel fiber had improved the mechanism of reinforcing effect and toughening effect of concrete material after burnt. With increasing of steel fiber volume rate, dynamic residual behavior of samples was improved. Microcosmic characteristics and energy absorption were induced for explaining the experiment results.
DEFF Research Database (Denmark)
Lundsgaard Hansen, Martin; Fallentin, Eva; Axelsen, Thomas;
2016-01-01
The purpose of this study was to assess inter- and intra-observer reproducibility of three different analytic methods to evaluate quantitative dynamic contrast-enhanced computed tomography (DCE-CT) measures from gastroesophageal junctional cancer. Twenty-five DCE-CT studies with gastroesophageal ...... were narrower for 3D analysis compared to 2D analysis. Three-dimensional volume DCE-CT analysis of gastroesophageal junction cancer provides higher inter- and intra-observer reproducibility with narrower limits of agreement between readers compared to 2D analysis.......The purpose of this study was to assess inter- and intra-observer reproducibility of three different analytic methods to evaluate quantitative dynamic contrast-enhanced computed tomography (DCE-CT) measures from gastroesophageal junctional cancer. Twenty-five DCE-CT studies with gastroesophageal...... for each observation. Inter- and intra-observer variability were assessed by Intraclass Correlation Coefficient (ICC) and Bland-Altman statistics. Interobserver ICC was excellent for arterial flow (0.88), for blood volume (0.89) and for permeability (0.91) with 3D-VOI analysis. The 95% limits of agreement...
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Bartoš, J., E-mail: Jozef.Bartos@savba.sk [Institute of SAS, Department of Structure and Physical Properties, Dúbravská cesta 9, 845 41 Bratislava (Slovakia); Švajdlenková, H. [Institute of SAS, Department of Structure and Physical Properties, Dúbravská cesta 9, 845 41 Bratislava (Slovakia); Zaleski, R. [Institute of Physics, Maria Curie-Sklodowska University, Pl. Marii Curie-Sklodowskiej 1, PL-20-031 Lublin (Poland); Edelmann, M. [Leibniz Institute of Polymer Research Dresden, Hohe Strasse 6, D-01069 Dresden (Germany); Lukešová, M. [Institute of SAS, Department of Structure and Physical Properties, Dúbravská cesta 9, 845 41 Bratislava (Slovakia)
2013-12-01
We report on a combined study of the guest dynamics and free volume in n-hexadecane (n-HXD) using two external microscopic probes: stable free radical 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) and ortho-positronium (o-Ps) by means of ESR or PALS, respectively. Dynamic behavior of the molecular TEMPO probe and annihilation properties of the atomistic o-Ps one as a function of temperature are compared. Two coincidencies between the crossover effects at the characteristic ESR and PALS temperatures T{sub 50G} and T{sub b1}{sup cr} below and T{sub X2}{sup fast} and T{sub m}{sup PALS} at the melting point T{sub m}{sup DSC} of n-HXD from macroscopic DSC scan were found. First, the slow to fast regime transition is ascribed to the spin probe TEMPO localization in the expanding interlamellar gap due to the induced enhanced end-chain mobility. Second, the high-temperature crossover within the fast regime is directly connected to the collective chain movements at the melting which takes place under the similar free volume fluctuation condition as revealed recently for a series of amorphous small molecular and polymer glass-formers.
Dynamic measures of regional lung air volume using phase contrast x-ray imaging
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Kitchen, M J; Lewis, R A; Morgan, M J; Siu, K K W; Habib, A [School of Physics, Monash University, Melbourne VIC 3800 (Australia); Wallace, M J; Siew, M L; Hooper, S B [Department of Physiology, Monash University, Melbourne VIC 3800 (Australia); Fouras, A [Division of Biological Engineering, Monash University, Melbourne VIC 3800 (Australia); Yagi, N; Uesugi, K [SPring-8/JASRI, Sayo, Hyogo 679-5198 (Japan)], E-mail: Marcus.Kitchen@sci.monash.edu.au
2008-11-07
Phase contrast x-ray imaging can provide detailed images of lung morphology with sufficient spatial resolution to observe the terminal airways (alveoli). We demonstrate that quantitative functional and anatomical imaging of lung ventilation can be achieved in vivo using two-dimensional phase contrast x-ray images with high contrast and spatial resolution (<100 {mu}m) in near real time. Changes in lung air volume as small as 25 {mu}L were calculated from the images of term and preterm rabbit pup lungs (n = 28) using a single-image phase retrieval algorithm. Comparisons with plethysmography and computed tomography showed that the technique provided an accurate and robust method of measuring total lung air volumes. Furthermore, regional ventilation was measured by partitioning the phase contrast images, which revealed differences in aeration for different ventilation strategies.
Lanspa, Michael J; Grissom, Colin K; Hirshberg, Eliotte L; Jones, Jason P; Brown, Samuel M
2013-02-01
Volume expansion is a mainstay of therapy in septic shock, although its effect is difficult to predict using conventional measurements. Dynamic parameters, which vary with respiratory changes, appear to predict hemodynamic response to fluid challenge in mechanically ventilated, paralyzed patients. Whether they predict response in patients who are free from mechanical ventilation is unknown. We hypothesized that dynamic parameters would be predictive in patients not receiving mechanical ventilation. This is a prospective, observational, pilot study. Patients with early septic shock and who were not receiving mechanical ventilation received 10-mL/kg volume expansion (VE) at their treating physician's discretion after initial resuscitation in the emergency department. We used transthoracic echocardiography to measure vena cava collapsibility index and aortic velocity variation before VE. We used a pulse contour analysis device to measure stroke volume variation (SVV). Cardiac index was measured immediately before and after VE using transthoracic echocardiography. Hemodynamic response was defined as an increase in cardiac index 15% or greater. Fourteen patients received VE, five of whom demonstrated a hemodynamic response. Vena cava collapsibility index and SVV were predictive (area under the curve = 0.83, 0.92, respectively). Optimal thresholds were calculated: vena cava collapsibility index, 15% or greater (positive predictive value, 62%; negative predictive value, 100%; P = 0.03); SVV, 17% or greater (positive predictive value 100%, negative predictive value 82%, P = 0.03). Aortic velocity variation was not predictive. Vena cava collapsibility index and SVV predict hemodynamic response to fluid challenge patients with septic shock who are not mechanically ventilated. Optimal thresholds differ from those described in mechanically ventilated patients.
Lanspa, Michael J.; Grissom, Colin K.; Hirshberg, Eliotte L.; Jones, Jason P.; Brown, Samuel M.
2013-01-01
Background Volume expansion is a mainstay of therapy in septic shock, although its effect is difficult to predict using conventional measurements. Dynamic parameters, which vary with respiratory changes, appear to predict hemodynamic response to fluid challenge in mechanically ventilated, paralyzed patients. Whether they predict response in patients who are free from mechanical ventilation is unknown. We hypothesized that dynamic parameters would be predictive in patients not receiving mechanical ventilation. Methods This is a prospective, observational, pilot study. Patients with early septic shock and who were not receiving mechanical ventilation received 10 ml/kg volume expansion (VE) at their treating physician's discretion after initial resuscitation in the emergency department. We used transthoracic echocardiography to measure vena cava collapsibility index (VCCI) and aortic velocity variation (AoVV) prior to VE. We used a pulse contour analysis device to measure stroke volume variation (SVV). Cardiac index was measured immediately before and after VE using transthoracic echocardiography. Hemodynamic response was defined as an increase in cardiac index ≥ 15%. Results 14 patients received VE, 5 of which demonstrated a hemodynamic response. VCCI and SVV were predictive (Area under curve = 0.83, 0.92, respectively). Optimal thresholds were calculated: VCCI ≥ 15% (Positive predictive value, PPV 62%, negative predictive value, NPV 100%, p = 0.03); SVV ≥ 17% (PPV 100%, NPV 82%, p = 0.03). AoVV was not predictive. Conclusions VCCI and SVV predict hemodynamic response to fluid challenge patients with septic shock who are not mechanically ventilated. Optimal thresholds differ from those described in mechanically ventilated patients. PMID:23324885
Automatic extraction of forward stroke volume using dynamic 11C-acetate PET/CT
DEFF Research Database (Denmark)
Harms, Hans; Tolbod, Lars Poulsen; Hansson, Nils Henrik;
, potentially introducing bias if measured with a separate modality. The aim of this study was to develop and validate methods for automatically extracting FSV directly from the dynamic PET used for measuring oxidative metabolism. Methods: 16 subjects underwent a dynamic 27 min PET scan on a Siemens Biograph...... TruePoint 64 PET/CT scanner after bolus injection of 399±27 MBq of 11C-acetate. The LV-aortic time-activity curve (TAC) was extracted automatically from dynamic PET data using cluster analysis. The first-pass peak was derived by automatic extrapolation of the down-slope of the TAC. FSV...... was then calculated as the injected dose divided by the product of heart rate and the area under the curve of the first-pass peak. Gold standard FSV was measured in the left ventricular outflow tract by cardiovascular magnetic resonance using phase-contrast velocity mapping within two weeks of PET imaging. Results...
DEFF Research Database (Denmark)
Borg, Michael; Hansen, Anders Melchior; Bredmose, Henrik
2016-01-01
to the extent that it becomes relevant to include in addition to the standard rigid body substructure modes which are typically described through linear radiation-diffraction theory. This paper describes a method for the inclusion of substructural flexibility in aero-hydro-servo-elastic dynamic simulations......Designing floating substructures for the next generation of 10MW and larger wind turbines has introduced new challenges in capturing relevant physical effects in dynamic simulation tools. In achieving technically and economically optimal floating substructures, structural flexibility may increase...
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Bezler, P.; Hartzman, M.; Reich, M.
1980-08-01
A set of benchmark problems and solutions have been developed for verifying the adequacy of computer programs used for dynamic analysis and design of nuclear piping systems by the Response Spectrum Method. The problems range from simple to complex configurations which are assumed to experience linear elastic behavior. The dynamic loading is represented by uniform support motion, assumed to be induced by seismic excitation in three spatial directions. The solutions consist of frequencies, participation factors, nodal displacement components and internal force and moment components. Solutions to associated anchor point motion static problems are not included.
Effect of dynamic contact angle in a volume of fluid (VOF) model for a microfluidic capillary flow.
Ashish Saha, Auro; Mitra, Sushanta K
2009-11-15
We perform three-dimensional numerical and experimental study of the dynamic contact angle using volume of fluid (VOF) method applied to microfluidic channels with integrated pillars. Initially, we evaluated different dynamic contact angle models (hydrodynamic, molecular kinetic and empirical) for capillary filling of a two-dimensional microchannel using analytical formulation. Further, the models which require a minimum prescription of adjustable parameters are only used for the study of capillary filling of microchannels with integrated pillars using different working fluids such as DI water, ethanol and isopropyl alcohol. Different microchannel geometry with varying diameter/height/spacing were studied for circular pillars. Effect of square pillars and changing the overall number of pillars on the capillary phenomena were also simulated. Our study demonstrated that the dynamic contact angle models modifies the transient response of the meniscus displacement and also the observed trends are model specific for the various microchannel geometries and working fluids. However, the different models have minimal effect on the meniscus profile. Different inlet boundary conditions were applied to observe the effect of grid resolution selected for numerical study on the capillary filling time. A grid dependent dynamic contact angle model which incorporates effective slip in the model was also used to observe the grid convergence of the numerical results. The grid independence was shown to improve marginally by applying the grid dependent dynamic contact angle model. Further we did numerical experiments of capillary filling considering variable surface wettability on the top and bottom walls of the microchannel with alternate hydrophilic-hydrophobic patterns. The meniscus front pinning was noticed for a high wetting contrast between the patterns. Non uniform streamline patterns indicated mixing of the fluid when using patterned walls. Such a microfluidic device with
METHODS OF CHAOTIC DYNAMICS IN SCHEMES OF RESEARCHES FEASIBILITY INTERNALS OF CAR TRAFFIC VOLUMES
Directory of Open Access Journals (Sweden)
H. A. Kramarenko
2011-04-01
Full Text Available The possibilities of chaotic dynamics methods applied to the topical analysis and forecasting problems of economic and technological properties of wagon streams represented by the related time series are studied. The advisability of using the generalized logistic map method for the construction of time series behavior operational forecasting is also determined.
Dynamic isotope power system (DIPS) applications study. Volume I. Summary. Final report
Energy Technology Data Exchange (ETDEWEB)
Prickett, W. Z.
1979-11-01
The Nuclear Integrated Multimission Spacecraft (NIMS) is designed for communications, surveillance, navigation and meteorelogical missions. This study assesses th attributes of the Dynamic Isotope Power System (DIPS) for this spacecraft. These attributes include cost, system and mission compatibility, and survivability. (LCL)
Modeling water sorption dynamics of cellular solid food systems using free volume theory
Meinders, M.B.J.; Vliet, van T.
2009-01-01
Water sorption and dynamical properties of bread crust were studied using gravimetric sorption experiments. Water uptake and loss were measured while relative humidity (RH) was step-wise in- or decreased. Experimental results were compared with Fickian diffusion models and empirical models like the
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Nichols, B.D.; Mueller, C.; Necker, G.A.; Travis, J.R.; Spore, J.W.; Lam, K.L.; Royl, P.; Redlinger, R.; Wilson, T.L.
1998-10-01
Los Alamos National Laboratory (LANL) and Forschungszentrum Karlsruhe (FzK) are developing GASFLOW, a three-dimensional (3D) fluid dynamics field code as a best-estimate tool to characterize local phenomena within a flow field. Examples of 3D phenomena include circulation patterns; flow stratification; hydrogen distribution mixing and stratification; combustion and flame propagation; effects of noncondensable gas distribution on local condensation and evaporation; and aerosol entrainment, transport, and deposition. An analysis with GASFLOW will result in a prediction of the gas composition and discrete particle distribution in space and time throughout the facility and the resulting pressure and temperature loadings on the walls and internal structures with or without combustion. A major application of GASFLOW is for predicting the transport, mixing, and combustion of hydrogen and other gases in nuclear reactor containments and other facilities. It has been applied to situations involving transporting and distributing combustible gas mixtures. It has been used to study gas dynamic behavior (1) in low-speed, buoyancy-driven flows, as well as sonic flows or diffusion dominated flows; and (2) during chemically reacting flows, including deflagrations. The effects of controlling such mixtures by safety systems can be analyzed. The code version described in this manual is designated GASFLOW 2.1, which combines previous versions of the United States Nuclear Regulatory Commission code HMS (for Hydrogen Mixing Studies) and the Department of Energy and FzK versions of GASFLOW. The code was written in standard Fortran 90. This manual comprises three volumes. Volume I describes the governing physical equations and computational model. Volume II describes how to use the code to set up a model geometry, specify gas species and material properties, define initial and boundary conditions, and specify different outputs, especially graphical displays. Sample problems are included
Cha, Chae Young; Noma, Akinori
2012-08-21
The cell volume continuously changes in response to varying physiological conditions, and mechanisms underlying volume regulation have been investigated in both experimental and theoretical studies. Here, general formulations concerning cell volume change are presented in the context of developing a comprehensive cell model which takes Ca(2+) dynamics into account. Explicit formulas for charge conservation and steady-state volumes of the cytosol and endoplasmic reticulum (ER) are derived in terms of membrane potential, amount of ions, Ca(2+)-bound buffer molecules, and initial cellular conditions. The formulations were applied to a ventricular myocyte model which has plasma-membrane Ca(2+) currents with dynamic gating mechanisms, Ca(2+)-buffering reactions with diffusive and non-diffusive buffer proteins, and Ca(2+) uptake into or release from the sarcoplasmic reticulum (SR) accompanied by compensatory cationic or anionic currents through the SR membrane. Time-dependent volume changes in cardiac myocytes induced by varying extracellular osmolarity or by action potential generation were successfully simulated by the novel formulations. Through application of bifurcation analysis, the existence and uniqueness of steady-state solutions of the cell volume were validated, and contributions of individual ion channels and transporters to the steady-state volume were systematically analyzed. The new formulas are consistent with previous fundamental theory derived from simple models of minimum compositions. The new formulations may be useful for examination of the relationship between cell function and volume change in other cell types.
Automatic extraction of forward stroke volume using dynamic 11C-acetate PET/CT
DEFF Research Database (Denmark)
Harms, Hans; Tolbod, Lars Poulsen; Hansson, Nils Henrik
was then calculated as the injected dose divided by the product of heart rate and the area under the curve of the first-pass peak. Gold standard FSV was measured in the left ventricular outflow tract by cardiovascular magnetic resonance using phase-contrast velocity mapping within two weeks of PET imaging. Results...... TruePoint 64 PET/CT scanner after bolus injection of 399±27 MBq of 11C-acetate. The LV-aortic time-activity curve (TAC) was extracted automatically from dynamic PET data using cluster analysis. The first-pass peak was derived by automatic extrapolation of the down-slope of the TAC. FSV...... = 0.001). Conclusions: FSV can be obtained automatically and reliably using dynamic 11C-acetate PET/CT and cluster analysis, although a small overestimation is observed when compared to FSV determined from MRI. This method could potentially be generalized to other tracers, although this requires...
A shock-fitting technique for cell-centered finite volume methods on unstructured dynamic meshes
Zou, Dongyang; Xu, Chunguang; Dong, Haibo; Liu, Jun
2017-09-01
In this work, the shock-fitting technique is further developed on unstructured dynamic meshes. The shock wave is fitted and regarded as a special boundary, whose boundary conditions and boundary speed (shock speed) are determined by solving Rankine-Hugoniot relations. The fitted shock splits the entire computational region into subregions, in which the flows are free from shocks and flow states are solved by a shock-capturing code based on arbitrary Lagrangian-Eulerian algorithm. Along with the motion of the fitted shock, an unstructured dynamic meshes algorithm is used to update the internal node's position to maintain the high quality of computational meshes. The successful applications prove the present shock-fitting to be a valid technique.
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Phillips, J.S.; Luke, B.A.; Long, J.W.; Lee, J.G.
1992-04-01
Tunnel damage resulting from seismic loading is an important issue for the Yucca Mountain nuclear waste repository. The tunnel dynamics experiment was designed to obtain and document ground motions, permanent displacements, observable changes in fracture patterns, and visible damage at ground motion levels of interest to the Yucca Mountain Project. Even though the maximum free-field loading on this tunnel was 28 g, the damage observed was minor. Fielding details, data obtained, and supporting documentation are reported.
Use of Dynamical Undulator Mechanism to Produce Short Wavelength Radiation in Volume FEL (VFEL)
Baryshevsky, V. G.; Batrakov, K. G.
2013-01-01
VFEL lasing in system with dynamical undulator is described. In this system radiation of long wavelength creates the undulator for lasing on shorter wavelength. Two diffraction gratings with different spatial periods form VFEL resonator. The grating with longer period pumps the resonator with long wavelength radiation to provide necessary amplitude of undulator field. The grating with shorter period makes mode selection for short wavelength radiation. Lasing of such a system in terahertz freq...
Automatic extraction of forward stroke volume using dynamic PET/CT
DEFF Research Database (Denmark)
Harms, Hans; Tolbod, Lars Poulsen; Hansson, Nils Henrik Stubkjær
2015-01-01
from PET data using cluster analysis. The first-pass peak was isolated by automatic extrapolation of the downslope of the TAC. FSV was calculated as the injected dose divided by the product of heart rate and the area under the curve of the first-pass peak. Gold standard FSV was measured using phase-contrast...... a dynamic 11 C-acetate PET scan on a Siemens Biograph TruePoint-64 PET/CT (scanner I). In addition, 10 subjects underwent both dynamic 15 O-water PET and 11 C-acetate PET scans on a GE Discovery-ST PET/CT (scanner II). The left ventricular (LV)-aortic time-activity curve (TAC) was extracted automatically.......001 for all). FSV based on 11 C-acetate and 15 O-water correlated highly (r = 0.99, slope = 1.03) with no significant difference between FSV estimates (p = 0.14). Conclusions FSV can be obtained automatically using dynamic PET/CT and cluster analysis. Results are almost identical for 11 C-acetate and 15 O...
Guendelman, Eduardo; Pacheva, Svetlana
2015-01-01
We propose a new class of gravity-matter-gauge theories in terms of two different non-Riemannian volume-forms independent of the Riemannian metric. The nonlinear gauge field system contains a square-root $\\sqrt{-F^2}$ of the standard Maxwell Lagrangian which is known to describe charge confinement in flat spacetime. In the physical Einstein frame we obtain an effective Lagrangian of "k-essence" type with quadratic dependence on the scalar "dilaton" kinetic term X, with a remarkable effective potential possessing two infinitely large flat regions as well as with nontrivial effective gauge coupling constants running with the "dilaton" $\\varphi$. Corresponding to the each of the two flat regions we find "vacuum" configurations of the following types: (i) $\\varphi = const$ and a non-zero gauge field vacuum $\\sqrt{-F^2}\
Cheng, Wei-Tso; Chen, Huan-Wen; Su, I-Hao; Fang, Ji-Tseng; Kuo, Han-Pin; Huang, Chien-Da
2015-12-01
Patients with asthma may also have vocal cord dysfunction (VCD), which leads to poor control of the asthma. Once patients are diagnosed with difficult-to-treat asthma with poor control, VCD should be excluded or treated accordingly. The gold standard for diagnosis of VCD is to perform a laryngoscopy. However, this procedure is invasive and may not be suitable for patients with difficult-to-treat asthma. Four-dimensional (4D) dynamic volume computed tomography (CT) is a noninvasive method for quantification of laryngeal movement, and can serve as an alternative for the diagnosis of VCD. Herein, we present a series of five cases with difficult-to-treat asthma patients who were diagnosed with VCD by 4D dynamic volume CT. Clinicians should be alert to the possibility of VCD when poor control is noted in patients with asthma. Early diagnosis by noninvasive 4D dynamic volume CT can decrease excessive doses of inhaled corticosteroids.
Directory of Open Access Journals (Sweden)
J. K. Wang
2001-01-01
Full Text Available I present a model of stock market price fluctuations incorporating effects of share supply as a history-dependent function of previous purchases and share demand as a function of price deviation from moving averages. Price charts generated show intervals of oscillations switching amplitude and frequency suddenly in time, forming price and trading volume patterns well-known in market technical analysis. Ultimate price trends agree with traditional predictions for specific patterns. The consideration of dynamically evolving supply and demand in this model resolves the apparent contradiction with the Efficient Market Hypothesis: perceptions of imprecise equity values by a world of investors evolve over non-negligible periods of time, with dependence on price history.
Directory of Open Access Journals (Sweden)
Hsun-Wen Chang
Full Text Available OBJECTIVES: The purpose of this study was to examine the correlation between the foot arch volume measured from static positions and the plantar pressure distribution during walking. METHODS: A total of 27 children, two to six years of age, were included in this study. Measurements of static foot posture were obtained, including navicular height and foot arch volume in sitting and standing positions. Plantar pressure, force and contact areas under ten different regions of the foot were obtained during walking. RESULTS: The foot arch index was correlated (r = 0.32 with the pressure difference under the midfoot during the foot flat phase. The navicular heights and foot arch volumes in sitting and standing positions were correlated with the mean forces and pressures under the first (r = -0.296∼-0.355 and second metatarsals (r = -0.335∼-0.504 and midfoot (r = -0.331∼-0.496 during the stance phase of walking. The contact areas under the foot were correlated with the foot arch parameters, except for the area under the midfoot. CONCLUSIONS: The foot arch index measured in a static position could be a functional index to predict the dynamic foot functions when walking. The foot arch is a factor which will influence the pressure distribution under the foot. Children with a lower foot arch demonstrated higher mean pressure and force under the medial forefoot and midfoot, and lower contact areas under the foot, except for the midfoot region. Therefore, children with flatfoot may shift their body weight to a more medial foot position when walking, and could be at a higher risk of soft tissue injury in this area.
SU(N) Gauge Theories with C-Periodic Boundary Conditions II. Small Volume Dynamics
Kronfeld, Andreas S
1993-01-01
The dynamics of SU(N) gauge theories, especially for N=3, in a small C-periodic box are investigated. We identify the fields that mimimize the energy---the torons---and determine which of these ``classical'' vacua are stable quantum mechanically. The stable torons break cubic symmetry, which has interesting consequences on the spectrum. At any of the stable torons there are also quartic modes. Since all C-periodic boundary conditions are gauge-equivalent, we choose a convenient version, for which the quartic modes are constant modes, and compute the effective Hamiltonian to one loop in perturbation theory.
Blade loss transient dynamics analysis, volume 1. Task 2: TETRA 2 theoretical development
Gallardo, Vincente C.; Black, Gerald
1986-01-01
The theoretical development of the forced steady state analysis of the structural dynamic response of a turbine engine having nonlinear connecting elements is discussed. Based on modal synthesis, and the principle of harmonic balance, the governing relations are the compatibility of displacements at the nonlinear connecting elements. There are four displacement compatibility equations at each nonlinear connection, which are solved by iteration for the principle harmonic of the excitation frequency. The resulting computer program, TETRA 2, combines the original TETRA transient analysis (with flexible bladed disk) with the steady state capability. A more versatile nonlinear rub or bearing element which contains a hardening (or softening) spring, with or without deadband, is also incorporated.
Econometrics and data of the 9 sector Dynamic General Equilibrium Model. Volume III. Final report
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Berndt, E.R.; Fraumeni, B.M.; Hudson, E.A.; Jorgenson, D.W.; Stoker, T.M.
1981-03-01
This report presents the econometrics and data of the 9 sector Dynamic General Equilibrium Model. There are two key components of 9DGEM - the model of household behavior and the model of produconcrneer behavior. The household model is concerned with decisions on consumption, saving, labor supply and the composition of consumption. The producer model is concerned with output price formation and determination of input patterns and purchases for each of the nine producing sectors. These components form the behavioral basis of DGEM. The remaining components are concerned with constraints, balance conditions, accounting, and government revenues and expenditures (these elements are developed in the report on the model specification).
Moukalled, F; Darwish, M
2016-01-01
This textbook explores both the theoretical foundation of the Finite Volume Method (FVM) and its applications in Computational Fluid Dynamics (CFD). Readers will discover a thorough explanation of the FVM numerics and algorithms used for the simulation of incompressible and compressible fluid flows, along with a detailed examination of the components needed for the development of a collocated unstructured pressure-based CFD solver. Two particular CFD codes are explored. The first is uFVM, a three-dimensional unstructured pressure-based finite volume academic CFD code, implemented within Matlab. The second is OpenFOAM®, an open source framework used in the development of a range of CFD programs for the simulation of industrial scale flow problems. With over 220 figures, numerous examples and more than one hundred exercise on FVM numerics, programming, and applications, this textbook is suitable for use in an introductory course on the FVM, in an advanced course on numerics, and as a reference for CFD programm...
Directory of Open Access Journals (Sweden)
Bas Versluis
Full Text Available OBJECTIVES: The aim of the current study was to describe a method that assesses the hyperemic microvascular blood plasma volume of the calf musculature. The reversibly albumin binding contrast agent gadofosveset was used in dynamic contrast-enhanced magnetic resonance imaging (DCE MRI to assess the microvascular status in patients with peripheral arterial disease (PAD and healthy controls. In addition, the reproducibility of this method in healthy controls was determined. MATERIALS AND METHODS: Ten PAD patients with intermittent claudication and 10 healthy control subjects were included. Patients underwent contrast-enhanced MR angiography of the peripheral arteries, followed by one DCE MRI examination of the musculature of the calf. Healthy control subjects were examined twice on different days to determine normative values and the interreader and interscan reproducibility of the technique. The MRI protocol comprised dynamic imaging of contrast agent wash-in under reactive hyperemia conditions of the calf musculature. Using pharmacokinetic modeling the hyperemic fractional microvascular blood plasma volume (V(p, unit: % of the anterior tibial, gastrocnemius and soleus muscles was calculated. RESULTS: V(p was significantly lower for all muscle groups in PAD patients (4.3±1.6%, 5.0±3.3% and 6.1±3.6% for anterior tibial, gastrocnemius and soleus muscles, respectively compared to healthy control subjects (9.1±2.0%, 8.9±1.9% and 9.3±2.1%. Differences in V(p between muscle groups were not significant. The coefficient of variation of V(p varied from 10-14% and 11-16% at interscan and interreader level, respectively. CONCLUSIONS: Using DCE MRI after contrast-enhanced MR angiography with gadofosveset enables reproducible assessment of hyperemic fractional microvascular blood plasma volume of the calf musculature. V(p was lower in PAD patients than in healthy controls, which reflects a promising functional (hemodynamic biomarker for the
Reorientation dynamics of nematics encapsulated in microscopic volumes in a strong electric field
Zakharov, A. V.; Vakulenko, A. A.; Pasechnik, S. V.
2016-09-01
We theoretically describe a new regime of reorientation of the director field widehat n and velocity v of a nematic liquid crystal (LC) encapsulated in a rectangular cell under the action of strong electric field E directed at angle α ( π/2) to the horizontal surfaces bounding the LC cell. The numerical calculations in the framework of nonlinear generalization of the classical Eriksen-Leslie theory showed that at certain relations between the torques and momenta affecting the unit LC volume and E ≫ E th, transition periodic structures can arise during reorientation of widehat n, if the corresponding distortion mode has the fastest response and, thus, suppresses all the rest of the modes, including uniform ones. The position of sites of these periodic structures is affected by the value of field E, angle α, and the character of anchoring of LC molecules to the bounding surfaces. The calculations performed for the nematic formed by 4-n-penthyl-4'-cyanobiphenyl showed that several vortexes can form in an LC cell under the action of reorientation of the nematic field; the boundaries of these vortexes are determined by the positions of periodic structure sites.
Blade loss transient dynamics analysis, volume 2. Task 2: TETRA 2 user's manual
Black, Gerald; Gallardo, Vincente C.
1986-01-01
This is the user's manual for the TETRA 2 Computer Code, a program developed in the NASA-Lewis Blade Loss Program. TETRA 2 calculates a turbine engine's dynamic structural response from applied stimuli. The calculation options are: (1) transient response; and (2) steady state forced response. Based on the method of modal syntheses, the program allows the use of linear, as well as nonlinear connecting elements. Both transient and steady state options can include: flexible Bladed Disk Module, and Nonlinear Connecting Elements (including deadband, hardening/softening spring). The transient option has the additional capability to calculate response with a squeeze film bearing module. TETRA 2 output is summarized in a plotfile which permits post processing such as FFT or graphical animation with the proper software and computer equipment.
Parallel implementation of a dynamic unstructured chimera method in the DLR finite volume TAU-code
Energy Technology Data Exchange (ETDEWEB)
Madrane, A.; Raichle, A.; Stuermer, A. [German Aerospace Center, DLR, Numerical Methods, Inst. of Aerodynamics and Flow Technology, Braunschweig (Germany)]. E-mail: aziz.madrane@dlr.de
2004-07-01
Aerodynamic problems involving moving geometries have many applications, including store separation, high-speed train entering into a tunnel, simulation of full configurations of the helicopter and fast maneuverability. Overset grid method offers the option of calculating these procedures. The solution process uses a grid system that discretizes the problem domain by using separately generated but overlapping unstructured grids that update and exchange boundary information through interpolation. However, such computations are complicated and time consuming. Parallel computing offers a very effective way to improve the productivity in doing computational fluid dynamics (CFD). Therefore the purpose of this study is to develop an efficient parallel computation algorithm for analyzing the flowfield of complex geometries using overset grids method. The strategy adopted in the parallelization of the overset grids method including the use of data structures and communication, is described. Numerical results are presented to demonstrate the efficiency of the resulting parallel overset grids method. (author)
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Sheu, D.L.
1978-09-01
The effects of tower motion on the dynamic response of a windmill rotor are studied. The blade lagging and side tower motion are taken into consideration in the analysis. The equations of motion for the system are a set of linear ordinary differential equations having periodic coefficients. The periodic coefficients of the equations of motion for a three bladed rotor are eliminated by using the multiblade coordinate transformation method. For a two bladed rotor, the equations of motion are solved by using the harmonic balance method. In addition to both methods, the Floquet Transition Matrix method is shown to be an effective way in dealing with the linear ordinary differential equations having periodic coefficients. The differences between the instability regions for a three bladed system and for a two bladed system are discussed.
Roques-Carmes, Thibault; Mathieu, Vincent; Gigante, Alexandra
2010-04-01
The dynamics of drop spreading of glycerol-water mixtures with and without surfactant on hydrophilic glass surfaces has been investigated. The influence of different factors, such as viscosity, drop volume and non-ionic alkyl (8-16) glucoside (Plantacare) surfactant concentration on the number and the nature of the spreading regimes is systematically investigated. More than 25 spreading experiments have been performed in order to obtain clear trends. The results confirm the existence of several spreading regimes for the duration of an experiment (200 s). For each regime, the radius can be expressed by a power law of the form R=Kt(n). Both n and K are necessary to identify the regime. The experimental data are compared with the analytical predictions of the combined theory of spreading. One of the main results of this study is that the nature of the regimes is strongly affected by the drop volume, the viscosity and the surfactant concentration. This behavior is not predicted by the theory. For drop volume less than or equal to 15 microL, a succession of two different regimes which depend on the viscosity and surfactant concentration are observed in the following order: a molecular-kinetic regime followed by a hydrodynamic regime (for high viscosity in the presence of surfactant) or a hydrodynamic regime and lastly a final asymptotic regime corresponding to a long relaxation time to equilibrium (for high viscosity in absence of surfactant and for low viscosity regardless of the presence of surfactant). The spreading follows quantitatively the predictions of the theory. Our results demonstrate that the theory is still valid for low viscosity liquids and in the presence of surfactant. The contact angle for which the crossover between molecular-kinetic regime and hydrodynamic regime occurs is thoroughly estimated since the theories do not allow the exact calculation of this value. Here for the first time, an empirical power law exponent (n=0.08+/-0.05) is proposed for
Institute of Scientific and Technical Information of China (English)
高传昌; 刘彩萍; 刘新阳; 苏泊源
2012-01-01
The effects of the operation parameters on the performance of the self-oscillating pulse jet device were investigated in this paper. The relationship between the operation parameters, such as working pressure, flow velocity, standoff distance, and the performance of the device was analyzed,and the optimal ranges of the operation parameters were obtained for the and self-oscillating pulse jet device, which provided references for the engineering applications.%运用自行研制的自激脉冲射流装置就其运行参数对装置性能的影响进行了试验研究.在自激脉冲射流装置结构参数一定的情况下,分析了工作压力、工作流速、靶距等运行参数与脉冲射流装置性能之间的关系,初步得出自激脉冲射流装置的最佳运行参数范围,为工程应用提供了依据.
1991-01-01
A Science Definition Team was established in December 1990 by the Space Physics Division, NASA, to develop a satellite program to conduct research on the energetics, dynamics, and chemistry of the mesosphere and lower thermosphere/ionosphere. This two-volume publication describes the TIMED (Thermosphere-Ionosphere-Mesosphere, Energetics and Dynamics) mission and associated science program. The report outlines the scientific objectives of the mission, the program requirements, and the approach towards meeting these requirements.
SRM Internal Flow Test and Computational Fluid Dynamic Analysis. Volume 1; Major Task Summaries
Whitesides, R. Harold; Dill, Richard A.; Purinton, David C.
1995-01-01
During the four year period of performance for NASA contract, NASB-39095, ERC has performed a wide variety of tasks to support the design and continued development of new and existing solid rocket motors and the resolution of operational problems associated with existing solid rocket motor's at NASA MSFC. This report summarizes the support provided to NASA MSFC during the contractual period of performance. The report is divided into three main sections. The first section presents summaries for the major tasks performed. These tasks are grouped into three major categories: full scale motor analysis, subscale motor analysis and cold flow analysis. The second section includes summaries describing the computational fluid dynamics (CFD) tasks performed. The third section, the appendices of the report, presents detailed descriptions of the analysis efforts as well as published papers, memoranda and final reports associated with specific tasks. These appendices are referenced in the summaries. The subsection numbers for the three sections correspond to the same topics for direct cross referencing.
Finite volume spectrum of 2D field theories from Hirota dynamics
Energy Technology Data Exchange (ETDEWEB)
Gromov, Nikolay [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)]|[Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik]|[St. Petersburg INP, Gatchina (Russian Federation); Kazakov, Vladimir [Univ. Paris-IV, Paris (France). Ecole Normale Superieure, Lab. de Physique Theorique; Vieira, Pedro [Max-Planck-Institut fuer Gravitationsphysik (Albert-Einstein-Institut), Potsdam (Germany)]|[Univ. do Porto (Portugal). Dept. de Fisica e Centro de Fisica do Porto Faculdade de Ciencias
2008-12-15
We propose, using the example of the O(4) sigma model, a general method for solving integrable two dimensional relativistic sigma models in a finite size periodic box. Our starting point is the so-called Y-system, which is equivalent to the thermodynamic Bethe ansatz equations of Yang and Yang. It is derived from the Zamolodchikov scattering theory in the cross channel, for virtual particles along the non-compact direction of the space-time cylinder. The method is based on the integrable Hirota dynamics that follows from the Y-system. The outcome is a nonlinear integral equation for a single complex function, valid for an arbitrary quantum state and accompanied by the finite size analogue of Bethe equations. It is close in spirit to the Destri-deVega (DdV) equation. We present the numerical data for the energy of various states as a function of the size, and derive the general Luescher-type formulas for the finite size corrections. We also re-derive by our method the DdV equation for the SU(2) chiral Gross-Neveu model. (orig.)
DEFF Research Database (Denmark)
Larsson, Henrik B W; Courivaud, Frédéric; Rostrup, Egill
2009-01-01
Assessment of vascular properties is essential to diagnosis and follow-up and basic understanding of pathogenesis in brain tumors. In this study, a procedure is presented that allows concurrent estimation of cerebral perfusion, blood volume, and blood-brain permeability from dynamic T(1)-weighted...
Harms, Hendrik Johannes; Tolbod, Lars Poulsen; Hansson, Nils Henrik Stubkjær; Kero, Tanja; Örndahl, Lovisa Holm; Kim, Won Yong; Bjerner, Tomas; Bouchelouche, Kirsten; Wiggers, Henrik; Frøkiær, Jørgen; Sörensen, Jens
2015-01-01
BACKGROUND: The aim of this study was to develop and validate an automated method for extracting forward stroke volume (FSV) using indicator dilution theory directly from dynamic positron emission tomography (PET) studies for two different tracers and scanners. METHODS: 35 subjects underwent a dynamic (11)C-acetate PET scan on a Siemens Biograph TruePoint-64 PET/CT (scanner I). In addition, 10 subjects underwent both dynamic (15)O-water PET and (11)C-acetate PET scans on a GE Discovery-ST PET...
Loading Processes Dynamics Modelling Taking into Account the Bucket-Soil Interaction
Directory of Open Access Journals (Sweden)
Carmen Debeleac
2007-10-01
Full Text Available The author propose three dynamic models specialized for the vibrations and resistive forces analysis that appear at the loading process with different construction equipment like frontal loaders and excavators.The models used putting into evidence the components of digging: penetration, cutting, and loading.The conclusions of this study consist by evidentiate the dynamic overloads that appear on the working state and that induced the self-oscillations into the equipment structure.
Rajappa, Chitra; Sringeri, S. Bhuvaneshwari; Subramanian, Yashonath; Gopalakrishnan, J.
2014-06-01
Extensive molecular dynamics studies of 13 different silica polymorphs are reported in the isothermal-isobaric ensemble with the Parrinello-Rahman variable shape simulation cell. The van Beest-Kramer-van Santen (BKS) potential is shown to predict lattice parameters for most phases within 2%-3% accuracy, as well as the relative stabilities of different polymorphs in agreement with experiment. Enthalpies of high-density polymorphs - CaCl2-type, α-PbO2-type, and pyrite-type - for which no experimental data are available as yet, are predicted here. Further, the calculated enthalpies exhibit two distinct regimes as a function of molar volume—for low and medium-density polymorphs, it is almost independent of volume, while for high-pressure phases a steep dependence is seen. A detailed analysis indicates that the increased short-range contributions to enthalpy in the high-density phases arise not only from an increased coordination number of silicon but also shorter Si-O bond lengths. Our results indicate that amorphous phases of silica exhibit better optimization of short-range interactions than crystalline phases at the same density while the magnitude of Coulombic contributions is lower in the amorphous phase.
Hindel, Stefan; Söhner, Anika; Maa, Marc; Sauerwein, Wolfgang; Baba, Hideo Andreas; Kramer, Martin; Lüdemann, Lutz
2017-01-01
The aim of our study was to assess the accuracy of fractional interstitial volume determination in low perfused and low vascularized tissue by using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). The fractional interstitial volume (ve) was determined in the medial thigh muscle of 12 female pigs by using a 3-dimensional gradient echo sequence with k-space sharing and administering gadolinium-based contrast agent (gadoterate meglumine). Analysis was performed using 3 pharmacokinetic models: the simple Tofts model (TM), the extended TM (ETM), and the 2-compartment exchange model (2CXM). We investigated the effect of varying acquisition durations (ADs) on the model parameter estimates of the 3 models and compared the ve values with the results of histological examinations of muscle sections of the medial thigh muscle. Histological measurements yielded a median value (25%-75% quartile) of 4.8% (3.7%-6.2%) for ve. The interstitial fractional volume determined by DCE-MRI was comparable to the histological results but varied strongly with AD for the TM and ETM. For the TM and the ETM, the results were virtually the same. Choosing arterial hematocrit to Hcta = 0.4, the lowest median ve value determined by DCE-MRI was 5.2% (3.3%-6.1%) for the ETM at a 6-minute AD. The maximum ve value determined with the ETM at a 15-minute AD was 7.7% (4.5%-9.0%). The variation with AD of median ve values obtained with the 2CXM was much smaller: 6.2% (3.1%-9.2%) for the 6-minute AD and 6.3% (4.3%-9.8%) for the 15-minute AD. The best fit for the 2CXM was found at the 10-minute AD with ve values of 6.6% (3.7%-8.2%). No significant correlation between the histological and any DCE-MRI modeling results was found. Considering the expected accuracy of histological measurements, the medians of the MR modeling results were in good agreement with the histological prediction. A parameter determination uncertainty was identified with the use of the TMs. This is due to underfitting and
Directory of Open Access Journals (Sweden)
Adèle Salin-Cantegrel
Full Text Available Loss-of-function of the potassium-chloride cotransporter 3 (KCC3 causes hereditary motor and sensory neuropathy with agenesis of the corpus callosum (HMSN/ACC, a severe neurodegenerative disease associated with defective midline crossing of commissural axons in the brain. Conversely, KCC3 over-expression in breast, ovarian and cervical cancer is associated with enhanced tumor cell malignancy and invasiveness. We identified a highly conserved proline-rich sequence within the C-terminus of the cotransporter which when mutated leads to loss of the KCC3-dependent regulatory volume decrease (RVD response in Xenopus Laevis oocytes. Using SH3 domain arrays, we found that this poly-proline motif is a binding site for SH3-domain containing proteins in vitro. This approach identified the guanine nucleotide exchange factor (GEF Vav2 as a candidate partner for KCC3. KCC3/Vav2 physical interaction was confirmed using GST-pull down assays and immuno-based experiments. In cultured cervical cancer cells, KCC3 co-localized with the active form of Vav2 in swelling-induced actin-rich protruding sites and within lamellipodia of spreading and migrating cells. These data provide evidence of a molecular and functional link between the potassium-chloride co-transporters and the Rho GTPase-dependent actin remodeling machinery in RVD, cell spreading and cell protrusion dynamics, thus providing new insights into KCC3's involvement in cancer cell malignancy and in corpus callosum agenesis in HMSN/ACC.
Boutou, Afroditi K; Zoumot, Zaid; Nair, Arjun; Davey, Claire; Hansell, David M; Jamurtas, Athanasios; Polkey, Michael I; Hopkinson, Nicholas S
2015-01-01
Dynamic hyperinflation (DH) is a pathophysiologic hallmark of Chronic Obstructive Pulmonary Disease (COPD). The aim of this study was to investigate the impact of emphysema distribution on DH during a maximal cardiopulmonary exercise test (CPET) in patients with severe COPD. This was a retrospective analysis of prospectively collected data among severe COPD patients who underwent thoracic high-resolution computed tomography, full lung function measurements and maximal CPET with inspiratory manouvers as assessment for a lung volume reduction procedure. ΔIC was calculated by subtracting the end-exercise inspiratory capacity (eIC) from resting IC (rIC) and expressed as a percentage of rIC (ΔIC%). Emphysema quantification was conducted at 3 predefined levels using the syngo PULMO-CT (Siemens AG); a difference >25% between best and worse slice was defined as heterogeneous emphysema. Fifty patients with heterogeneous (62.7% male; 60.9 ± 7.5 years old; FEV1% = 32.4 ± 11.4) and 14 with homogeneous emphysema (61.5% male; 62.5 ± 5.9 years old; FEV1% = 28.1 ± 10.3) fulfilled the enrolment criteria. The groups were matched for all baseline variables. ΔIC% was significantly higher in homogeneous emphysema (39.8% ± 9.8% vs.31.2% ± 13%, p = 0.031), while no other CPET parameter differed between the groups. Upper lobe predominance of emphysema correlated positively with peak oxygen pulse, peak oxygen uptake and peak respiratory rate, and negatively with ΔIC%. Homogeneous emphysema is associated with more DH during maximum exercise in COPD patients.
Adam, A.; Pavlidis, D.; Percival, J. R.; Salinas, P.; Xie, Z.; Fang, F.; Pain, C. C.; Muggeridge, A. H.; Jackson, M. D.
2016-09-01
A general, higher-order, conservative and bounded interpolation for the dynamic and adaptive meshing of control-volume fields dual to continuous and discontinuous finite element representations is presented. Existing techniques such as node-wise interpolation are not conservative and do not readily generalise to discontinuous fields, whilst conservative methods such as Grandy interpolation are often too diffusive. The new method uses control-volume Galerkin projection to interpolate between control-volume fields. Bounded solutions are ensured by using a post-interpolation diffusive correction. Example applications of the method to interface capturing during advection and also to the modelling of multiphase porous media flow are presented to demonstrate the generality and robustness of the approach.
Maric, Tomislav; Bothe, Dieter
2013-01-01
A new parallelized unsplit geometrical Volume of Fluid (VoF) algorithm with support for arbitrary unstructured meshes and dynamic local Adaptive Mesh Refinement (AMR), as well as for two and three dimensional computation is developed. The geometrical VoF algorithm supports arbitrary unstructured meshes in order to enable computations involving flow domains of arbitrary geometrical complexity. The implementation of the method is done within the framework of the OpenFOAM library for Computational Continuum Mechanics (CCM) using the C++ programming language with modern policy based design for high program code modularity. The development of the geometrical VoF algorithm significantly extends the method base of the OpenFOAM library by geometrical volumetric flux computation for two-phase flow simulations. For the volume fraction advection, a novel unsplit geometrical algorithm is developed, which inherently sustains volume conservation utilizing unique Lagrangian discrete trajectories located in the mesh points. ...
Energy Technology Data Exchange (ETDEWEB)
Goettler, Jens; Preibisch, Christine [TU Muenchen, Department of Neuroradiology, Klinikum rechts der Isar, Munich (Germany); TU Muenchen, TUM Neuroimaging Center (TUM-NIC), Klinikum rechts der Isar, Munich (Germany); Lukas, Mathias; Mustafa, Mona; Schwaiger, Markus; Pyka, Thomas [TU Muenchen, Department of Nuclear Medicine, Klinikum rechts der Isar, Munich (Germany); Kluge, Anne; Kaczmarz, Stephan; Zimmer, Claus [TU Muenchen, Department of Neuroradiology, Klinikum rechts der Isar, Munich (Germany); Gempt, Jens; Ringel, Florian; Meyer, Bernhard [TU Muenchen, Department of Neurosurgery, Klinikum rechts der Isar, Munich (Germany); Foerster, Stefan [TU Muenchen, TUM Neuroimaging Center (TUM-NIC), Klinikum rechts der Isar, Munich (Germany); TU Muenchen, Department of Nuclear Medicine, Klinikum rechts der Isar, Munich (Germany); Klinikum Bayreuth, Department of Nuclear Medicine, Bayreuth (Germany)
2017-03-15
{sup 18}F-fluorethyltyrosine-(FET)-PET and MRI-based relative cerebral blood volume (rCBV) have both been used to characterize gliomas. Recently, inter-individual correlations between peak static FET-uptake and rCBV have been reported. Herein, we assess the local intra-lesional relation between FET-PET parameters and rCBV. Thirty untreated glioma patients (27 high-grade) underwent simultaneous PET/MRI on a 3 T hybrid scanner obtaining structural and dynamic susceptibility contrast sequences. Static FET-uptake and dynamic FET-slope were correlated with rCBV within tumour hotspots across patients and intra-lesionally using a mixed-effects model to account for inter-individual variation. Furthermore, maximal congruency of tumour volumes defined by FET-uptake and rCBV was determined. While the inter-individual relationship between peak static FET-uptake and rCBV could be confirmed, our intra-lesional, voxel-wise analysis revealed significant positive correlations (median r = 0.374, p < 0.0001). Similarly, significant inter- and intra-individual correlations were observed between FET-slope and rCBV. However, rCBV explained only 12% of the static and 5% of the dynamic FET-PET variance and maximal overlap of respective tumour volumes was 37% on average. Our results show that the relation between peak values of MR-based rCBV and static FET-uptake can also be observed intra-individually on a voxel basis and also applies to a dynamic FET parameter, possibly determining hotspots of higher biological malignancy. However, just a small part of the FET-PET signal variance is explained by rCBV and tumour volumes determined by the two modalities showed only moderate overlap. These findings indicate that FET-PET and MR-based rCBV provide both congruent and complimentary information on glioma biology. (orig.)
Modelling of Nonlinear Dynamic of Mechanic Systems with the Force Tribological Interaction
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K.A. Nuzhdin
2015-09-01
Full Text Available This paper considers the mechanisms with different structure: tribometric device and a mechanism for handling of optical glasses. In the first device, the movement of the upper platform is due to a reciprocating friction interaction. In the second device, the processing of the optical element or group of elements occurs due to the rotational motion. Modelling of the dynamic of these systems with Matlab/Simmechanic allowed carrying out the analysis of dynamic of mechanisms, considering nonlinearity tribological interactions for these systems. The article shows that using of the computer models can effectively carry out the selection of the control parameters to create the desired mode of operation, as well as to investigate the behaviour of systems with nonlinear parameters and processes of self-oscillations. The organization of the managed self-oscillation process is realized to create the relevant high-performance manufacturing, for example, for the processing of optical glasses.
Directory of Open Access Journals (Sweden)
Inseon Ryoo
Full Text Available PURPOSE: To evaluate the usefulness of dynamic susceptibility contrast (DSC enhanced perfusion MR imaging in predicting major genetic alterations in glioblastomas. MATERIALS AND METHODS: Twenty-five patients (M:F = 13∶12, mean age: 52.1±15.2 years with pathologically proven glioblastoma who underwent DSC MR imaging before surgery were included. On DSC MR imaging, the normalized relative tumor blood volume (nTBV of the enhancing solid portion of each tumor was calculated by using dedicated software (Nordic TumorEX, NordicNeuroLab, Bergen, Norway that enabled semi-automatic segmentation for each tumor. Five major glioblastoma genetic alterations (epidermal growth factor receptor (EGFR, phosphatase and tensin homologue (PTEN, Ki-67, O6-methylguanine-DNA methyltransferase (MGMT and p53 were confirmed by immunohistochemistry and analyzed for correlation with the nTBV of each tumor. Statistical analysis was performed using the unpaired Student t test, ROC (receiver operating characteristic curve analysis and Pearson correlation analysis. RESULTS: The nTBVs of the MGMT methylation-negative group (mean 9.5±7.5 were significantly higher than those of the MGMT methylation-positive group (mean 5.4±1.8 (p = .046. In the analysis of EGFR expression-positive group, the nTBVs of the subgroup with loss of PTEN gene expression (mean: 10.3±8.1 were also significantly higher than those of the subgroup without loss of PTEN gene expression (mean: 5.6±2.3 (p = .046. Ki-67 labeling index indicated significant positive correlation with the nTBV of the tumor (p = .01. CONCLUSION: We found that glioblastomas with aggressive genetic alterations tended to have a high nTBV in the present study. Thus, we believe that DSC-enhanced perfusion MR imaging could be helpful in predicting genetic alterations that are crucial in predicting the prognosis of and selecting tailored treatment for glioblastoma patients.
Energy Technology Data Exchange (ETDEWEB)
Taylor, L.L.; Wilson, J.R.; Sanchez, L.Z.; Aguilar, R.; Trellue, H.R.; Cochrane, K.; Rath, J.S.
1998-10-01
The US Department of Energy Office of Environmental Management's (DOE/EM's) National Spent Nuclear Fuel Program (NSNFP), through a collaboration between Sandia National Laboratories (SNL) and Idaho National Engineering and Environmental Laboratory (INEEL), is conducting a systematic Nuclear Dynamics Consequence Analysis (NDCA) of the disposal of SNFs in an underground geologic repository sited in unsaturated tuff. This analysis is intended to provide interim guidance to the DOE for the management of the SNF while they prepare for final compliance evaluation. This report presents results from a Nuclear Dynamics Consequence Analysis (NDCA) that examined the potential consequences and risks of criticality during the long-term disposal of spent nuclear fuel owned by DOE-EM. This analysis investigated the potential of post-closure criticality, the consequences of a criticality excursion, and the probability frequency for post-closure criticality. The results of the NDCA are intended to provide the DOE-EM with a technical basis for measuring risk which can be used for screening arguments to eliminate post-closure criticality FEPs (features, events and processes) from consideration in the compliance assessment because of either low probability or low consequences. This report is composed of an executive summary (Volume 1), the methodology and results of the NDCA (Volume 2), and the applicable appendices (Volume 3).
Guimarães, Fernando S; Moço, Vanessa J R; Menezes, Sara L S; Dias, Cristina M; Salles, Raquel E B; Lopes, Agnaldo J
2012-04-01
Although respiratory physical therapy is considered fundamental in the treatment of hypersecretive patients, there is little evidence of its physiological and therapeutic effects in bronchiectasis patients. To evaluate the acute physiological effects of ELTGOL and Flutter VRP1® in dynamic and static lung volumes in patients with bronchiectasis and, secondarily, to study the effect of these techniques in sputum elimination. Patients with clinical and radiological diagnosis of bronchiectasis were included. Patients underwent three interventions in a randomized order and with a one-week washout interval between them. Before all interventions patients inhaled two puffs of 100 mcg of salbutamol. There was a cough period of five minutes before and after the control protocol and the interventions (ELTGOL and Flutter VRP1®). After each cough series patients underwent assessments of dynamic and static lung volumes by spirometry and plethysmography. The expectorated secretions were collected during the interventions and during the second cough series, and quantified by its dry weight. We studied 10 patients, two males and eight females (mean age: 55.9±18.1 years). After using Flutter VRP1®and ELTGOL there was a significant decrease in residual volume (RV), functional residual capacity (FRC) and total lung capacity (TLC) (pELTGOL compared with Control and Flutter VRP1® (pELTGOL and Flutter VRP1® techniques acutely reduced lung hyperinflation, but only the ELTGOL increased the removal of pulmonary secretions from patients with bronchiectasis.
Energy Technology Data Exchange (ETDEWEB)
Taylor, L.L.; Wilson, J.R.; Sanchez, L.C.; Aguilar, R.; Trellue, H.R.; Cochrane, K.; Rath, J.S.
1998-10-01
The US Department of Energy Office of Environmental Management's (DOE/EM's) National Spent Nuclear Fuel Program (NSNFP), through a collaboration between Sandia National Laboratories (SNL) and Idaho National Engineering and Environmental Laboratory (INEEL), is conducting a systematic Nuclear Dynamics Consequence Analysis (NDCA) of the disposal of SNFs in an underground geologic repository sited in unsaturated tuff. This analysis is intended to provide interim guidance to the DOE for the management of the SNF while they prepare for final compliance evaluation. This report presents results from a Nuclear Dynamics Consequence Analysis (NDCA) that examined the potential consequences and risks of criticality during the long-term disposal of spent nuclear fuel owned by DOE-EM. This analysis investigated the potential of post-closure criticality, the consequences of a criticality excursion, and the probability frequency for post-closure criticality. The results of the NDCA are intended to provide the DOE-EM with a technical basis for measuring risk which can be used for screening arguments to eliminate post-closure criticality FEPs (features, events and processes) from consideration in the compliance assessment because of either low probability or low consequences. This report is composed of an executive summary (Volume 1), the methodology and results of the NDCA (Volume 2), and the applicable appendices (Volume 3).
Institute of Scientific and Technical Information of China (English)
LIU Qian; YE Jing-ming; XU Ling; DUAN Xue-ning; ZHAO Jian-xin; LIU Yin-hua
2012-01-01
Background Earlier studies have examined the association between the diameter of primary tumors measured by magnetic resonance imaging (MRI) and histopathology in breast cancer patients.However,the diameter does not completely describe the dimensions of the breast tumor or its volumetric proportion relative to the whole breast.The association between breast tumor volume/breast volume ratios measured by these two techniques has not been reported.Methods Seventy-three patients were recruited from female patients with primary breast tumors admitted to our center between January and December 2010.They were divided into two groups.Group A (n=46) underwent modified radical mastectomy (MRM),and Group B (n=27) underwent preoperative neoadjuvant chemotherapy before MRM.They were examined by dynamic-contrast enhanced MRI (DCE-MRI) to measure breast volumes (BVs),tumor volumes (TVs),and tumor volume/breast volume ratios (TV/BV).These measurements were compared with histopathology results after MRM,and the associations between MRI and pathology were analyzed by linear regression and Bland-Altman analysis.Results For Group A,the correlation coefficients for BVs,TVs,and TV/BV ratios measured by the two techniques were 0.938,0.921,and 0.897 (all P ＜0.001),respectively.For Group B,the correlation coefficients for BVs,TVs,and TV/BV ratios were 0.936,0.902,and 0.869 (all P＜0.01),respectively.The results suggest statistically significant correlations between these parameters measured by the two techniques for both groups.Conclusion For these patients,BVs,TVs,and TV/BV ratios measured by DCE-MRI significantly correlated with those determined by histopathology.
Institute of Scientific and Technical Information of China (English)
李崇贵; 斯林; 赵宪文
2001-01-01
The components and functions of all parts of forest volume dynamic monitoring system based on remote sensing (RS), geographic information system (GIS) and the global positioning system (GPS) are presented. The various volume estimate models included in the system are sketched. The action and application of the system in forest resource quantitative monitoring is analyzed through practical example.
Visser, E.P.; Philippens, M.E.P.; Kienhorst, L.; Kaanders, J.H.A.M.; Corstens, F.H.M.; Geus-Oei, L.F. de; Oyen, W.J.G.
2008-01-01
Tumor delineation using noninvasive medical imaging modalities is important to determine the target volume in radiation treatment planning and to evaluate treatment response. It is expected that combined use of CT and functional information from 18F-FDG PET will improve tumor delineation. However, u
Kim, Dongmin; Mun, Jeong-Beom; Kim, Eun Young; Moon, Jeonggeun
2013-01-01
Occurrence of dynamic left ventricular outflow tract (LVOT) obstruction is not infrequent in critically ill patients, and it is associated with potential danger. Here, we report a case of transient heart failure with hemodynamic deterioration paradoxically induced by extreme dehydration. This article describes clinical features of the patient and echocardiographic findings of dynamic LVOT obstruction and significant mitral regurgitation caused by systolic anterior motion of the mitral valve i...
Directory of Open Access Journals (Sweden)
Antonio J. Torregrosa
2017-05-01
Full Text Available Duct junctions play a major role in the operation and design of most piping systems. The objective of this paper is to establish the potential of a staggered mesh finite volume model as a way to improve the description of the effect of simple duct junctions on an otherwise one-dimensional flow system, such as the intake or exhaust of an internal combustion engine. Specific experiments have been performed in which different junctions have been characterized as a multi-port, and that have provided precise and reliable results on the propagation of pressure pulses across junctions. The results obtained have been compared to simulations performed with a staggered mesh finite volume method with different flux limiters and different meshes and, as a reference, have also been compared with the results of a more conventional pressure loss-based model. The results indicate that the staggered mesh finite volume model provides a closer description of wave dynamics, even if further work is needed to establish the optimal calculation settings.
Salinas, P.; Jackson, M.; Pavlidis, D.; Pain, C.; Adam, A.; Xie, Z.; Percival, J. R.
2015-12-01
We present a new, high-order, control-volume-finite-element (CVFE) method with discontinuous representation for pressure and velocity to simulate multiphase flow in heterogeneous porous media. Time is discretized using an adaptive, fully implicit method. Heterogeneous geologic features are represented as volumes bounded by surfaces. Within these volumes, termed geologic domains, the material properties are constant. A given model typically contains numerous such geologic domains. Our approach conserves mass and does not require the use of CVs that span domain boundaries. Computational efficiency is increased by use of dynamic mesh optimization, in which an unstructured mesh adapts in space and time to key solution fields, such as pressure, velocity or saturation, whilst preserving the geometry of the geologic domains. Up-, cross- or down-scaling of material properties during mesh optimization is not required, as the properties are uniform within each geologic domain. We demonstrate that the approach, amongst other features, accurately preserves sharp saturation changes associated with high aspect ratio geologic domains such as fractures and mudstones, allowing efficient simulation of flow in highly heterogeneous models. Moreover, accurate solutions are obtained at significantly lower computational cost than an equivalent fine, fixed mesh and conventional CVFE methods. The use of implicit time integration allows the method to efficiently converge using highly anisotropic meshes without having to reduce the time-step. The work is significant for two key reasons. First, it resolves a long-standing problem associated with the use of classical CVFE methods to model flow in highly heterogeneous porous media, in which CVs span boundaries between domains of contrasting material properties. Second, it reduces computational cost/increases solution accuracy through the use of dynamic mesh optimization and time-stepping with large Courant number.
Wu, Zhe-bin; Cao, Hong; Liu, Ting; Wu, Ze-qian; Ke, Wei-min; Gao, Zhi-liang
2012-10-01
The aim of this study was to determine the dynamic expression profile of hepatitis B surface antigen (HBsAg) according to hepatic parenchyma cells' volume at different stages of liver fibrosis during the immune clearance phase. Eighty-nine patients with HBeAg-positive chronic hepatitis B (CHB) in the immune clearance stage were recruited for study. Each patient's serum HBsAg levels were detected by electrochemiluminescence. The serum HBsAg levels were apportioned according to hepatic parenchyma cells' volume at liver fibrosis stages 1, 2, 3, and 4 and compared by ANOVA. The unapportioned serum HBsAg levels (IU/mL) at liver fibrosis stages 1 (227.2+/-237.7), 2 (211.0+/-131.4), 3(300.1+/-144.6), and 4 (278.7+/-148.8) were not significantly different (all comparisons, P range: 0.061 to 0.759). However, when the serum HBsAg levels were apportioned by the same hepatic parenchyma cells' volume at liver fibrosis stages 1 (343.9+/-359.8), 2 (336.4+/-209.5), 3 (508.7+/-245.1), and 4 (525.2+/-274.8), the levels were significantly different (all comparisons, F = 3.045 and P = 0.033; stage 1 vs. 3, P = 0.041; stage 1 vs. 4, P = 0.046; stage 2 vs. 3, P = 0.028; stage 2 vs. 4, P = 0.034). During the immune clearance phase of chronic hepatitis B, increased HBsAg expression is associated with increased hepatic parenchyma cells' volume and progressive liver fibrosis stage.
Bartoš, J.; Švajdlenková, H.
2017-02-01
The rotation dynamics of the spin probe TEMPO in glycerol from ESR is compared with the ortho-positronium (o-Ps) annihilation from PALS and interpreted using the relaxation dynamics from BDS. Rotation time scale within the slow motion regime exhibits two Arrhenius regions with the characteristic ESR temperature, TX1τ, close to the characteristic PALS temperature, Tb1L, which is related to the secondary β process above Tg. Next, a slow to fast motion regime transition at the characteristic ESR temperature, Tcτ, close to the characteristic PALS temperature, Tb2L, followed by non-Arrhenius fast motion regime region is fully coupled with the primary α process.
Energy Technology Data Exchange (ETDEWEB)
Fu, Jun; Chen, Wei-jian; Wang, Mei-hao; Li, Jian-ce; Zhang, Qian; Xia, Neng-zhi; Yang, Yun-jun [Wenzhou Medical University, Department of Radiology, First Affiliated Hospital, Wenzhou (China); Wu, Gui-yun [Cleveland Clinics Foundation, Department of Nuclear Medicine, Imaging Institute, Cleveland, OH (United States); Cheng, Jing-liang; Zhang, Yong [Zhengzhou University, Department of Radiology, First Affiliated Hospital, Zhengzhou (China); Zhuge, Qichuan [Wenzhou Medical University, Department of Neurosurgery, First Affiliated Hospital, Wenzhou (China)
2014-11-09
The purpose of this study was to evaluate the value of 320-detector row CT used to detect crossed cerebellar diaschisis (CCD) in patients with unilateral supratentorial spontaneous intracerebral hemorrhage (SICH). We investigated 62 of 156 patients with unilateral supratentorial SICH using 320-detector row CT scanning. Regional cerebral blood flow (rCBF), cerebral blood volume (rCBV), mean transit time (rMTT), and time to peak (rTTP) levels were measured in different regions of interest (ROIs) that were manually outlined on computed tomography perfusion (CTP) for the cerebrum, including normal-appearing brain tissue that surrounded the perilesional low-density area (NA) and the perihematomal low-density area (PA) in all patients and the cerebellum (ipsilateral and contralateral) in CCD-positive patients. Of 62 cases, a total of 14 met the criteria for CCD due to cerebellar perfusion asymmetry on CTP maps. In the quantitative analysis, significant differences were found in the perfusion parameters between the contralateral and ipsilateral cerebellum in CCD-positive cases. No significant differences were found between the CCD-positive group and the CCD-negative group according to the hematoma volume, NIHSS scores, and cerebral perfusion abnormality (each P > 0.05). The correlation analysis of the degree of NA, PA perfusion abnormality, and the degree of CCD severity showed negative and significant linear correlations (R, -0.66∝-0.56; P < 0.05). 320-detector row CT is a robust and practicable method for the comprehensive primary imaging work-up of CCD in unilateral supratentorial SICH patients. (orig.)
Shavykin, Oleg V; Neelov, Igor M; Darinskii, Anatolii A
2016-09-21
The effect of excluded volume (EV) interactions on the manifestation of the local dynamics in the spin-lattice NMR relaxation in dendrimers has been studied by using Brownian dynamics simulations. The study was motivated by the theory developed by Markelov et al., [J. Chem. Phys., 2014, 140, 244904] for a Gaussian dendrimer model without EV interactions. The theory connects the experimentally observed dependence of the spin-lattice relaxation rate 1/T(1)H on the location of NMR active groups with the restricted flexibility (semiflexibility) of dendrimers. Semiflexibility was introduced through the correlations between the orientations of different segments. However, these correlations exist even in flexible dendrimer models with EV interactions. We have simulated coarse-grained flexible and semiflexible dendrimer models with and without EV interactions. Every dendrimer segment consisted of two rigid bonds. Semiflexibility was introduced through a potential which restricts the fluctuations of angles between neighboring bonds but does not change orientational correlations in the EV model as compared to the flexible case. The frequency dependence of the reduced 1/T(1)H(ωH) for segments and bonds belonging to different dendrimer shells was calculated. It was shown that the main effect of EV interactions consists of a much stronger contribution of the overall dendrimer rotation to the dynamics of dendrimer segments as compared to phantom models. After the exclusion of this contribution the manifestation of internal dynamics in spin-lattice NMR relaxation appears to be practically insensitive to EV interactions. For the flexible models, the position ωmax of the peak of the modified 1/T(1)H(ωH) does not depend on the shell number. For semiflexible models, the maximum of 1/T(1)H(ωH) for internal segments or bonds shifts to lower frequencies as compared to outer ones. The dependence of ωmax on the number of dendrimer shells appears to be universal for segments and
Shrestha, Kalyan; Mompean, Gilmar; Calzavarini, Enrico
2016-02-01
A finite-volume (FV) discretization method for the lattice Boltzmann (LB) equation, which combines high accuracy with limited computational cost is presented. In order to assess the performance of the FV method we carry out a systematic comparison, focused on accuracy and computational performances, with the standard streaming lattice Boltzmann equation algorithm. In particular we aim at clarifying whether and in which conditions the proposed algorithm, and more generally any FV algorithm, can be taken as the method of choice in fluid-dynamics LB simulations. For this reason the comparative analysis is further extended to the case of realistic flows, in particular thermally driven flows in turbulent conditions. We report the successful simulation of high-Rayleigh number convective flow performed by a lattice Boltzmann FV-based algorithm with wall grid refinement.
1993-09-15
Alamos National Labor.lory, MS B-258, Los Alamos, NM 87545. Cellular automata, Interacting particle systems USA Adaptive dynamics C.K.R.T. JONES...exhibit resonant be- mensions of the junctions are 200 am by 10/um haviour at all multipla n of one half-wavelength and they are closely spaced in...conjugated --electron molecules Brian M. Pierce Hughes Aircraft Company, Bldg. R02, MS V518, P.O. Box 92426, Los Angeles, CA 90009-2426, USA The nonresonant w
Berry, R. L.; Tegart, J. R.; Demchak, L. J.
1979-01-01
Space shuttle propellant dynamics during ET/Orbiter separation in the RTLS (return to launch site) mission abort sequence were investigated in a test program conducted in the NASA KC-135 "Zero G" aircraft using a 1/10th-scale model of the ET LOX Tank. Low-g parabolas were flown from which thirty tests were selected for evaluation. Data on the nature of low-g propellant reorientation in the ET LOX tank, and measurements of the forces exerted on the tank by the moving propellent will provide a basis for correlation with an analytical model of the slosh phenomenon.
Bainum, P. M.; Kumar, V. K.
1980-01-01
The dynamics and stability of large orbiting flexible beams, and platforms and dish type structures oriented along the local horizontal are treated both analytically and numerically. It is assumed that such structures could be gravitationally stabilized by attaching a rigid light-weight dumbbell at the center of mass by a spring loaded hinge which also could provide viscous damping. For the beam, the small amplitude inplane pitch motion, dumbbell librational motion, and the anti-symmetric elastic modes are all coupled. The three dimensional equations of motion for a circular flat plate and shallow spherical shell in orbit with a two-degree-of freedom gimballed dumbbell are also developed and show that only those elastic modes described by a single nodal diameter line are influenced by the dumbbell motion. Stability criteria are developed for all the examples and a sensitivity study of the system response characteristics to the key system parameters is carried out.
Shima, Eiji; Yoshida, Kenji; Amano, Kanichi
1987-11-01
An automatic grid generator for multiple element airfoils was developed and the existing implicit Total Variation Diminishing (TVD) finite volume code was improved in both accuracy and efficiency, in order to make the Navier-Stokes solver a practical design tool for high lift devices. Utilizing these codes, Navier-Stokes analysis of the single slotted flap was carried out. The automatic grid generator utilizes the elliptic equation solver using the finite difference method combined with the panel method. The flow field is divided into subregions by the dividing stream lines which are calculated by the panel method and the computational grid in each subregion is generated by solving the elliptic equations (Thompson's method). Since the panel method can solve the potential flow around any number of arbitrary shaped bodies, this grid generator can generate a H-type computational grid around such bodies automatically. To obtain a high accuracy on a rapidly stretching grid, the flow solver uses the TVD formulation containing an explicit treatment of nonuniform grid spacing. Converging rate and numerical stability of the flow solver is augmented by the relaxation approach using Symmetric Point Gauss Seidel method in matrix inversion process which is necessary for an implicit scheme.
Kemp, Victoria R.
1992-01-01
A fluid-dynamic, digital-transient computer model of an integrated, parallel propulsion system was developed for the CDC mainframe and the SUN workstation computers. Since all STME component designs were used for the integrated system, computer subroutines were written characterizing the performance and geometry of all the components used in the system, including the manifolds. Three transient analysis reports were completed. The first report evaluated the feasibility of integrated engine systems in regards to the start and cutoff transient behavior. The second report evaluated turbopump out and combined thrust chamber/turbopump out conditions. The third report presented sensitivity study results in staggered gas generator spin start and in pump performance characteristics.
1995-01-01
A computational fluid dynamics (CFD) analysis has been performed on the aft slot region of the Titan 4 Solid Rocket Motor Upgrade (SRMU). This analysis was performed in conjunction with MSFC structural modeling of the propellant grain to determine if the flow field induced stresses would adversely alter the propellant geometry to the extent of causing motor failure. The results of the coupled CFD/stress analysis have shown that there is a continual increase of flow field resistance at the aft slot due to the aft segment propellant grain being progressively moved radially toward the centerline of the motor port. This 'bootstrapping' effect between grain radial movement and internal flow resistance is conducive to causing a rapid motor failure.
Energy Technology Data Exchange (ETDEWEB)
Kandel, Sonja; Kloeters, Christian; Meyer, Henning; Hein, Patrick; Rogalla, Patrik [Charite - Universitaetsmedizin Berlin, Department of Radiology, Campus Charite Mitte, Berlin (Germany); Hilbig, Andreas [Charite - University Medicine, Medical Clinic III - Hematology and Oncology, Campus Virchow Klinikum, Berlin (Germany)
2009-11-15
The purpose of this study was to evaluate a whole-organ perfusion protocol of the pancreas in patients with primary pancreas carcinoma and to analyse perfusion differences between normal and diseased pancreatic tissue. Thirty patients with primary pancreatic malignancy were imaged on a 320-slice CT unit. Twenty-nine cancers were histologically proven. CT data acquisition was started manually after contrast-material injection (8 ml/s, 350 mg iodine/ml) and dynamic density measurements in the right ventricle. After image registration, perfusion was determined with the gradient-relationship technique and volume regions-of-interest were defined for perfusion measurements. Contrast time-density curves and perfusion maps were generated. Statistical analysis was performed using the Kolmogorov-Smirnov test for analysis of normal distribution and Kruskal-Wallis test (nonparametric ANOVA) with Bonferroni correction for multiple stacked comparisons. In all 30 patients the entire pancreas was imaged, and registration could be completed in all cases. Perfusion of pancreatic carcinomas was significantly lower than of normal pancreatic tissue (P < 0.001) and could be visualized on colored perfusion maps. The 320-slice CT allows complete dynamic visualization of the pancreas and enables calculation of whole-organ perfusion maps. Perfusion imaging carries the potential to improve detection of pancreatic cancers due to the perfusion differences. (orig.)
Zaghi, S.
2014-07-01
OFF, an open source (free software) code for performing fluid dynamics simulations, is presented. The aim of OFF is to solve, numerically, the unsteady (and steady) compressible Navier-Stokes equations of fluid dynamics by means of finite volume techniques: the research background is mainly focused on high-order (WENO) schemes for multi-fluids, multi-phase flows over complex geometries. To this purpose a highly modular, object-oriented application program interface (API) has been developed. In particular, the concepts of data encapsulation and inheritance available within Fortran language (from standard 2003) have been stressed in order to represent each fluid dynamics "entity" (e.g. the conservative variables of a finite volume, its geometry, etc…) by a single object so that a large variety of computational libraries can be easily (and efficiently) developed upon these objects. The main features of OFF can be summarized as follows: Programming LanguageOFF is written in standard (compliant) Fortran 2003; its design is highly modular in order to enhance simplicity of use and maintenance without compromising the efficiency; Parallel Frameworks Supported the development of OFF has been also targeted to maximize the computational efficiency: the code is designed to run on shared-memory multi-cores workstations and distributed-memory clusters of shared-memory nodes (supercomputers); the code's parallelization is based on Open Multiprocessing (OpenMP) and Message Passing Interface (MPI) paradigms; Usability, Maintenance and Enhancement in order to improve the usability, maintenance and enhancement of the code also the documentation has been carefully taken into account; the documentation is built upon comprehensive comments placed directly into the source files (no external documentation files needed): these comments are parsed by means of doxygen free software producing high quality html and latex documentation pages; the distributed versioning system referred as git
Kimura, Yuichi; Seki, Chie; Hashizume, Nobuya; Yamada, Takashi; Wakizaka, Hidekatsu; Nishimoto, Takahiro; Hatano, Kentaro; Kitamura, Keishi; Toyama, Hiroshi; Kanno, Iwao
2013-11-21
This study aimed to develop a new system, named CD-Well, for mouse PET dynamic study. CD-Well allows the determination of time-activity curves (TACs) for arterial whole blood and plasma using 2-3 µL of blood per sample; the minute sample size is ideal for studies in small animals. The system has the following merits: (1) measures volume and radioactivity of whole blood and plasma separately; (2) allows measurements at 10 s intervals to capture initial rapid changes in the TAC; and (3) is compact and easy to handle, minimizes blood loss from sampling, and delay and dispersion of the TAC. CD-Well has 36 U-shaped channels. A drop of blood is sampled into the opening of the channel and stored there. After serial sampling is completed, CD-Well is centrifuged and scanned using a flatbed scanner to define the regions of plasma and blood cells. The length measured is converted to volume because the channels have a precise and uniform cross section. Then, CD-Well is exposed to an imaging plate to measure radioactivity. Finally, radioactivity concentrations are computed. We evaluated the performance of CD-Well in in vitro measurement and in vivo (18)F-fluorodeoxyglucose and [(11)C]2-carbomethoxy-3β-(4-fluorophenyl) tropane studies. In in vitro evaluation, per cent differences (mean±SE) from manual measurement were 4.4±3.6% for whole blood and 4.0±3.5% for plasma across the typical range of radioactivity measured in mouse dynamic study. In in vivo studies, reasonable TACs were obtained. The peaks were captured well, and the time courses coincided well with the TAC derived from PET imaging of the heart chamber. The total blood loss was less than 200 µL, which had no physiological effect on the mice. CD-Well demonstrates satisfactory performance, and is useful for mouse PET dynamic study.
Energy Technology Data Exchange (ETDEWEB)
Sykes, R.I.; Lewellen, W.S.; Parker, S.F.; Henn, D.S.
1989-01-01
The Second Order Closure Integrated Puff Model (SCIPUFF) is the intermediate resolution member of a hierarchy of models. It simulates the expected values of plume concentration downwind of a fossil-fueled power plant stack, along with an estimate of the variation around this value. To represent the turbulent atmosphere surrounding the plume compatibly with available meteorological data, a second order closure sub-model is used. SCIPUFF represents the plume by a series of Gaussian puffs, typically 10 seconds apart; plume growth is calculated by a random walk phase combined with plume expansion calculated from the volume integrals of the equations used in the Stack Exhaust Model (SEM), the highest resolution model. Meteorological uncertainty is accounted for by means of extra dispersion terms. SCIPUFF was tested against more than 250 hours of plume data including both a level site and a moderately complex terrain site; approximately 200 samplers were used. Model predictions were evaluated by comparing the measured ground level concentration distribution to that simulated by the model. Further, the simulated and actual distributions of deviations between simulated or observed and expected values were compared. The predicted distributions were close to the measured ones. The overall results from SCIPUFF were similar to those from the lowest resolution model, SCIMP. The advantage of SCIPUFF is its flexibility for including future improvements. When combined with a suitable mesoscale model, SCIPUFF may be able to simulate plume dispersion beyond the 50 km limit of other available models. The ability to cover a wide range of time and space scales in a single calculation is another valuable feature. 3 refs., 10 figs., 4 tabs.
Directory of Open Access Journals (Sweden)
J. Ungermann
2015-06-01
Full Text Available The Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA is an airborne infrared limb imager combining a two-dimensional infrared detector with a Fourier transform spectrometer. It was operated aboard the new German Gulfstream G550 High Altitude LOng Range (HALO research aircraft during the Transport And Composition in the upper Troposphere/lowermost Stratosphere (TACTS and Earth System Model Validation (ESMVAL campaigns in summer 2012. This paper describes the retrieval of temperature and trace gas (H2O, O3, HNO3 volume mixing ratios from GLORIA dynamics mode spectra that are spectrally sampled every 0.625 cm−1. A total of 26 integrated spectral windows are employed in a joint fit to retrieve seven targets using consecutively a fast and an accurate tabulated radiative transfer model. Typical diagnostic quantities are provided including effects of uncertainties in the calibration and horizontal resolution along the line of sight. Simultaneous in situ observations by the Basic Halo Measurement and Sensor System (BAHAMAS, the Fast In-situ Stratospheric Hygrometer (FISH, an ozone detector named Fairo, and the Atmospheric chemical Ionization Mass Spectrometer (AIMS allow a validation of retrieved values for three flights in the upper troposphere/lowermost stratosphere region spanning polar and sub-tropical latitudes. A high correlation is achieved between the remote sensing and the in situ trace gas data, and discrepancies can to a large extent be attributed to differences in the probed air masses caused by different sampling characteristics of the instruments. This 1-D processing of GLORIA dynamics mode spectra provides the basis for future tomographic inversions from circular and linear flight paths to better understand selected dynamical processes of the upper troposphere and lowermost stratosphere.
Martyr-Koller, R.C.; Kernkamp, H.W.J.; Van Dam, Anne A.; Mick van der Wegen,; Lucas, Lisa; Knowles, N.; Jaffe, B.; Fregoso, T.A.
2017-01-01
A linked modeling approach has been undertaken to understand the impacts of climate and infrastructure on aquatic ecology and water quality in the San Francisco Bay-Delta region. The Delft3D Flexible Mesh modeling suite is used in this effort for its 3D hydrodynamics, salinity, temperature and sediment dynamics, phytoplankton and water-quality coupling infrastructure, and linkage to a habitat suitability model. The hydrodynamic model component of the suite is D-Flow FM, a new 3D unstructured finite-volume model based on the Delft3D model. In this paper, D-Flow FM is applied to the San Francisco Bay-Delta to investigate tidal, seasonal and annual dynamics of water levels, river flows and salinity under historical environmental and infrastructural conditions. The model is driven by historical winds, tides, ocean salinity, and river flows, and includes federal, state, and local freshwater withdrawals, and regional gate and barrier operations. The model is calibrated over a 9-month period, and subsequently validated for water levels, flows, and 3D salinity dynamics over a 2 year period.Model performance was quantified using several model assessment metrics and visualized through target diagrams. These metrics indicate that the model accurately estimated water levels, flows, and salinity over wide-ranging tidal and fluvial conditions, and the model can be used to investigate detailed circulation and salinity patterns throughout the Bay-Delta. The hydrodynamics produced through this effort will be used to drive affiliated sediment, phytoplankton, and contaminant hindcast efforts and habitat suitability assessments for fish and bivalves. The modeling framework applied here will serve as a baseline to ultimately shed light on potential ecosystem change over the current century.
Institute of Scientific and Technical Information of China (English)
曾廷敏; 林祥友; 王勇
2013-01-01
The dynamic relationships between price and volume of CSI 300 stock index futures are empirically examined based on 5 minutes high frequency transaction price and volume data of CSI 300 stock index futures contracts , and the results show that there is obviously positive direction relationship between price volatility and trading volume and between relative trading volume and relative position volume , but there is significantly negative direction relation with position volume , that there is obviously positive relationship between the volatility and expected trading volume or unexpected trading volume , furthermore , the positive influence of unexpected trading volume is bigger , that there is significantly negative relationship between the volatility and expected position volume or unexpected position volume , furthermore , the negative influence of unexpected position volume is bigger , that the influence of the change of trading volume and position volume on the volatility of stock index futures price is asymmetric , and that the influence of the shock of positive trading volume and position volume is bigger than that of negative trading volume and position volume , i.e.the influence on price volatility is bigger when unexpected trading volume and unexpected position volume are positive .The supervisors and investors in stock index futures market can analyze the changing trends of the implicit indicators such as price volatility and market risk and so on by monitoring explicit indicators such as trading volume , position volume , relatively trading volume , relative position volume and so on as well as their changes in order to implement proper supervising policies and trading policies .%利用沪深300股指期货合约的5分钟高频交易价量数据，分析股指期货合约的价量特征及其动态关系，结果表明：股指期货合约的价格波动率与成交量、相对成交量和相对持仓量之间均存在显著正向关系，而与持仓
Energy Technology Data Exchange (ETDEWEB)
Wirestam, R.; Knutsson, L.; Risberg, J.; Boerjesson, S.; Larsson, E.M.; Gustafson, L.; Passant, U.; Staahlberg, F. [Depts. of Medical Radiation Physics, Diagnostic Radiology, Psychiatry, and Psychogeriatrics, Lund Univ, Lund (Sweden)
2007-07-15
Background: Attempts to retrieve absolute values of cerebral blood flow (CBF) by dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) have typically resulted in overestimations. Purpose: To improve DSC-MRI CBF estimates by calibrating the DSC-MRI-based cerebral blood volume (CBV) with a corresponding T1-weighted (T1W) steady-state (ss) CBV estimate. Material and Methods: 17 volunteers were investigated by DSC-MRI and 133Xe SPECT. Steady-state CBV calculation, assuming no water exchange, was accomplished using signal values from blood and tissue, before and after contrast agent, obtained by T1W spin-echo imaging. Using steady-state and DSC-MRI CBV estimates, a calibration factor K = CBV(ss)/CBV(DSC) was obtained for each individual. Average whole-brain CBF(DSC) was calculated, and the corrected MRI-based CBF estimate was given by CBF(ss) = KxCBF(DSC). Results: Average whole-brain SPECT CBF was 40.1{+-}6.9 ml/min 100 g, while the corresponding uncorrected DSC-MRI-based value was 69.2{+-}13.8 ml/mi 100 g. After correction with the calibration factor, a CBF(ss) of 42.7{+-}14.0 ml/min 100 g was obtained. The linear fit to CBF(ss)-versus-CBF(SPECT) data was close to proportionality (R = 0.52). Conclusion: Calibration by steady-state CBV reduced the population average CBF to a reasonable level, and a modest linear correlation with the reference 133Xe SPECT technique was observed. Possible explanations for the limited accuracy are, for example, large-vessel partial-volume effects, low post-contrast signal enhancement in T1W images, and water-exchange effects.
Energy Technology Data Exchange (ETDEWEB)
Li, C [Fox Chase Cancer Center, Philadelphia, PA (United States); Renmin Hospital of Wuhan University, Wuhan, Hubei Province (China); Wang, B; Dong, Z; Ma, C [Fox Chase Cancer Center, Philadelphia, PA (United States); Ge, W; Xu, L [Renmin Hospital of Wuhan University, Wuhan, Hubei Province (China)
2015-06-15
Purpose: Radio-dynamic therapy (RDT) is a potentially effective modality for local and systemic cancer treatment. Using RDT, the administration of a radio-sensitizer enhances the biological effect of high-energy photons. Although the sensitizer uptake ratio of tumor to normal tissue is normally high, one cannot simply neglect its effect on critical structures. In this study, we aim to explore planning strategies to improve bone marrow sparing without compromising the plan quality for RDT treatment of pelvic cancers. Methods: Ten cervical and ten prostate cancer patients who previously received radiotherapy at our institution were selected for this study. For each patient, nine plans were created using the Varian Eclipse treatmentplanning-system (TPS) with 3D-CRT, IMRT, and VMAT delivery techniques containing various gantry angle combinations and optimization parameters (dose constraints to the bone marrow). To evaluate the plans for bone marrow sparing, the dose-volume parameters V5, V10, V15, V20, V30, and V40 for bone marrow were examined. Effective doseenhancement factors for the sensitizer were used to weigh the dose-volume histograms for various tissues from individual fractions. Results: The planning strategies had different impacts on bone marrow sparing for the cervical and prostate cases. For the cervical cases, provided the bone marrow constraints were properly set during optimization, the dose to bone marrow sparing was found to be comparable between different IMRT and VMAT plans regardless of the gantry angle selection. For the prostate cases, however, careful selection of gantry angles could dramatically improve the bone marrow sparing, although the dose distribution in bone marrow was clinically acceptable for all prostate plans that we created. Conclusion: For intensity-modulated RDT planning for cervical cancer, planners should set bone marrow constraints properly to avoid any adverse damage, while for prostate cancer one can carefully select gantry
Institute of Scientific and Technical Information of China (English)
华仁海; 仲伟俊
2003-01-01
We examine the dynamic relation between returns, volume, and volatility of our futures markets. The results show that there exists a positive correlation between absolute returns and volume, but no correlation between returns and volume; Granger causality demonstrate that no causality relation exists between returns (or absolute returns) and volume, except copper's absolute returns causes volume; the conditional volatility of returns has no direct impact to futures returns; copper' and soybean' trading volume contributes strong explanatory power to volatility, but aluminous' trading volume has no direct impact to volatility.
Energy Technology Data Exchange (ETDEWEB)
Wiesmann, Martin [University of Munich, Department of Neuroradiology, Muenchen (Germany); Klinikum der Universitaet Muenchen - Grosshadern, Abteilung fuer Neuroradiologie, Muenchen (Germany); Berg, Scott; Stoeckelhuber, B.M. [University of Luebeck, Department of Radiology, Luebeck (Germany); Bohner, G.; Klingebiel, R. [University Medicine Berlin, Department of Neuroradiology, Charite, Berlin (Germany); Schoepf, V.; Yousry, I.; Linn, J. [University of Munich, Department of Neuroradiology, Muenchen (Germany); Missler, U. [Evangelisches Krankenhaus Duisburg-Nord, Department of Neuroradiology, Duisburg (Germany)
2008-12-15
The influence of the frequency of computed tomography (CT) image acquistion on the diagnostic quality of dynamic perfusion CT (PCT) studies of the brain was investigated. Eight patients with clinically suspected acute ischemia of one hemisphere underwent PCT, performed on average 3.4 h after the onset of symptoms. Sixty consecutive images per slice were obtained with individual CT images obtained at a temporal resolution of two images per second. Eight additional data sets were reconstructed with temporal resolutions ranging from one image per second to one image per 5 s. Cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) measurements were performed in identical regions of interest. Two neuroradiologists evaluated the PCT images visually to identify areas of abnormal perfusion. Perfusion images created up to a temporal resolution of one image per 3 s were rated to be diagnostically equal to the original data. Even at one image per 4 s, all areas of infarction were identified. Quantitative differences of CBF, CBV and MTT measurements were {<=}10% up to one image per 3 s. For PCT of the brain, temporal resolution can be reduced to one image per 3 s without significant compromise in image quality. This significantly reduces the radiation dose of the patient. (orig.)
Goodman, Lawrence E
2001-01-01
Beginning text presents complete theoretical treatment of mechanical model systems and deals with technological applications. Topics include introduction to calculus of vectors, particle motion, dynamics of particle systems and plane rigid bodies, technical applications in plane motions, theory of mechanical vibrations, and more. Exercises and answers appear in each chapter.
Astuti, Valerio; Rovelli, Carlo
2016-01-01
Building on a technical result by Brunnemann and Rideout on the spectrum of the Volume operator in Loop Quantum Gravity, we show that the dimension of the space of the quadrivalent states --with finite-volume individual nodes-- describing a region with total volume smaller than $V$, has \\emph{finite} dimension, bounded by $V \\log V$. This allows us to introduce the notion of "volume entropy": the von Neumann entropy associated to the measurement of volume.
APPLICATION OF MODIFIED CONVERSION METHOD TO A NONLINEAR DYNAMICAL SYSTEM
Directory of Open Access Journals (Sweden)
G.I. Melnikov
2015-01-01
Full Text Available The paper deals with a mathematical model of dynamical system with single degree of freedom, presented in the form of ordinary differential equations with nonlinear parts in the form of polynomials with constant and periodic coefficients. A modified method for the study of self-oscillations of nonlinear mechanical systems is presented. A refined method of transformation and integration of the equation, based on Poincare-Dulac normalization method has been developed. Refinement of the method lies in consideration of higher order nonlinear terms by Chebyshev economization technique that improves the accuracy of the calculations. Approximation of the higher order remainder terms by homogeneous forms of lower orders is performed; in the present case, it is done by cubic forms. An application of the modified method for the Van-der-Pol equation is considered as an example; the expressions for the amplitude and the phase of the oscillations are obtained in an analytical form. The comparison of the solution of the Van-der-Pol equation obtained by the developed method and the exact solution is performed. The error of the solution obtained by the modified method equals to 1%, which shows applicability of the developed method for analysis of self-oscillations of nonlinear dynamic systems with constant and periodic parameters.
Bronchoscopic lung volume reduction
Directory of Open Access Journals (Sweden)
M. I. Polkey
2006-12-01
Full Text Available Surgical lung volume reduction can improve exercise performance and forced expiratory volume in one second in patients with emphysema. However, the procedure is associated with a 5% mortality rate and a nonresponse rate of 25%. Accordingly, interest has focused on alternative ways of reducing lung volume. Two principle approaches are used: collapse of the diseased area using blockers placed endobronchially and the creation of extrapulmonary pathways. Preliminary data from the former approach suggest that it can be successful and that the magnitude of success is related to reduction in dynamic hyperinflation.
Energy Technology Data Exchange (ETDEWEB)
Thomsen, H. (Den Sundhedsfaglige Kandidatuddannelse, Aarhus Universitet Bygning 1264, Aarhus (Denmark); University College Nordjylland, Aalborg (Denmark)), Email: hnt@ucn.dk; Steffensen, E. (Aalborg Hospital/Aarhus University Hospital, Department of Radiology, Aalborg (Denmark)); Larsson, E. M. (Aalborg Hospital/Aarhus University Hospital, Department of Radiology, Aalborg (Denmark); Uppsala University Hospital, Department of Radiology, Uppsala (Sweden))
2012-02-15
Background. Perfusion magnetic resonance imaging (MRI) is increasingly used in the evaluation of brain tumors. Relative cerebral blood volume (rCBV) is usually obtained by dynamic susceptibility contrast (DSC) MRI using normal appearing white matter as reference region. The emerging perfusion technique arterial spin labelling (ASL) presently provides measurement only of cerebral blood flow (CBF), which has not been widely used in human brain tumor studies. Purpose. To assess if measurement of blood flow is comparable with measurement of blood volume in human biopsy-proven gliomas obtained by DSC-MRI using two different regions for normalization and two different measurement approaches. Material and Methods. Retrospective study of 61 patients with different types of gliomas examined with DSC perfusion MRI. Regions of interest (ROIs) were placed in tumor portions with maximum perfusion on rCBF and rCBV maps, with contralateral normal appearing white matter and cerebellum as reference regions. Larger ROIs were drawn for histogram analyses. The type and grade of the gliomas were obtained by histopathology. Statistical comparison was made between diffuse astrocytomas, anaplastic astrocytomas, and glioblastomas. Results. rCBF and rCBV measurements obtained with the maximum perfusion method were correlated when normalized to white matter (r = 0.60) and to the cerebellum (r = 0.49). Histogram analyses of rCBF and rCBV showed that mean and median values as well as skewness and peak position were correlated (0.61 < r < 0.93), whereas for kurtosis and peak height, the correlation coefficient was about 0.3 when comparing rCBF and rCBV values for the same reference region. Neither rCBF nor rCBV quantification provided a statistically significant difference between the three types of gliomas. However, both rCBF and rCBV tended to increase with tumor grade and to be lower in patients who had undergone resection/treatment. Conclusion. rCBF measurements normalized to white matter
Cronin, Drew T; Woloszynek, Stephen; Morra, Wayne A; Honarvar, Shaya; Linder, Joshua M; Gonder, Mary Katherine; O'Connor, Michael P; Hearn, Gail W
2015-01-01
Bushmeat hunting is extensive in west and central Africa as both a means for subsistence and for commercial gain. Commercial hunting represents one of the primary threats to wildlife in the region, and confounding factors have made it challenging to examine how external factors influence the commercial bushmeat trade. Bioko Island, Equatorial Guinea is a small island with large tracts of intact forest that support sizeable populations of commercially valuable vertebrates, especially endemic primates. The island also has a low human population and has experienced dramatic economic growth and rapid development since the mid-1990's. From October 1997 - September 2010, we monitored the largest bushmeat market on Bioko in Malabo, recording over 197,000 carcasses for sale. We used these data to analyze the dynamics of the market in relation to political events, environmental legislation, and rapid economic growth. Our findings suggest that bushmeat hunting and availability increased in parallel with the growth of Equatorial Guinea's GDP and disposable income of its citizens. During this 13-year study, the predominant mode of capture shifted from trapping to shotguns. Consequently, carcass volume and rates of taxa typically captured with shotguns increased significantly, most notably including intensified hunting of Bioko's unique and endangered monkey fauna. Attempts to limit bushmeat sales, including a 2007 ban on primate hunting and trade, were only transiently effective. The hunting ban was not enforced, and was quickly followed by a marked increase in bushmeat hunting compared to hunting rates prior to the ban. Our results emphasize the negative impact that rapid development and unenforced legislation have had on Bioko's wildlife, and demonstrate the need for strong governmental support if conservation strategies are to be successful at preventing extinctions of tropical wildlife.
Ochiai, Nobuo; Sasamoto, Kikuo; Tsunokawa, Jun; Hoffmann, Andreas; Okanoya, Kazunori; MacNamara, Kevin
2015-11-20
An extension of multi-volatile method (MVM) technology using the combination of a standard dynamic headspace (DHS) configuration, and a modified DHS configuration incorporating an additional vacuum module, was developed for milliliter injection volume of aqueous sample with full sample evaporation. A prior step involved investigation of water management by weighing of the water residue in the adsorbent trap. The extended MVM for 1 mL aqueous sample consists of five different DHS method parameter sets including choice of the replaceable adsorbent trap. An initial two DHS sampling sets at 25°C with the standard DHS configuration using a carbon-based adsorbent trap target very volatile solutes with high vapor pressure (>10 kPa) and volatile solutes with moderate vapor pressure (1-10 kPa). Subsequent three DHS sampling sets at 80°C with the modified DHS configuration using a Tenax TA trap target solutes with low vapor pressure (88%) for 17 test aroma compounds and moderate recoveries (44-71%) for 4 test compounds. The method showed good linearity (r(2)>0.9913) and high sensitivity (limit of detection: 0.1-0.5 ng mL(-1)) even with MS scan mode. The improved sensitivity of the method was demonstrated with analysis of a wide variety of aroma compounds in brewed green tea. Compared to the original 100 μL MVM procedure, this extension to 1 mL MVM allowed detection of nearly twice the number of aroma compounds, including 18 potent aroma compounds from top-note to base-note (e.g. 2,3-butanedione, coumarin, furaneol, guaiacol, cis-3-hexenol, linalool, maltol, methional, 3-methyl butanal, 2,3,5-trimethyl pyrazine, and vanillin). Sensitivity for 23 compounds improved by a factor of 3.4-15 under 1 mL MVM conditions.
Bamford, D
2002-01-01
The work described in this thesis is concerned with the study of the local free volume measured by Positron Annihilation Spectroscopy and its correlation with the physical, chemical and structural properties of polymers. The average size of the local free volume holes in branched poly(ethylene-co-olefin) and poly(propylene-co-olefin) copolymers is studied using Positron Annihilation Lifetime Spectroscopy PALS and correlated with the number and length of the branches and the physical properties determined from Differential Scanning Calorimetry DSC and density measurements. The presence of the n-alkyl branches were found to form sterical hindrances to an effective chain packing resulting in a linear increase in the average free volume hole sizes, an increase in the specific volume of the amorphous phase, a decrease in the sample crystallinity and a decrease in the glass transition and melting temperatures. A linear relation was found between the average size of the free volume holes and the glass transition tem...
Hindel, Stefan; Söhner, Anika; Maaß, Marc; Sauerwein, Wolfgang; Möllmann, Dorothe; Baba, Hideo Andreas; Kramer, Martin; Lüdemann, Lutz
2017-01-01
The purpose of this study was to assess the accuracy of fractional blood volume (vb) estimates in low-perfused and low-vascularized tissue using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). The results of different MRI methods were compared with histology to evaluate the accuracy of these methods under clinical conditions. vb was estimated by DCE-MRI using a 3D gradient echo sequence with k-space undersampling in five muscle groups in the hind leg of 9 female pigs. Two gadolinium-based contrast agents (CA) were used: a rapidly extravasating, extracellular, gadolinium-based, low-molecular-weight contrast agent (LMCA, gadoterate meglumine) and an extracellular, gadolinium-based, albumin-binding, slowly extravasating blood pool contrast agent (BPCA, gadofosveset trisodium). LMCA data were evaluated using the extended Tofts model (ETM) and the two-compartment exchange model (2CXM). The images acquired with administration of the BPCA were used to evaluate the accuracy of vb estimation with a bolus deconvolution technique (BD) and a method we call equilibrium MRI (EqMRI). The latter calculates the ratio of the magnitude of the relaxation rate change in the tissue curve at an approximate equilibrium state to the height of the same area of the arterial input function (AIF). Immunohistochemical staining with isolectin was used to label endothelium. A light microscope was used to estimate the fractional vascular area by relating the vascular region to the total tissue region (immunohistochemical vessel staining, IHVS). In addition, the percentage fraction of vascular volume was determined by multiplying the microvascular density (MVD) with the average estimated capillary lumen, [Formula: see text], where d = 8μm is the assumed capillary diameter (microvascular density estimation, MVDE). Except for ETM values, highly significant correlations were found between most of the MRI methods investigated. In the cranial thigh, for example, the vb medians
Söhner, Anika; Maaß, Marc; Sauerwein, Wolfgang; Möllmann, Dorothe; Baba, Hideo Andreas; Kramer, Martin; Lüdemann, Lutz
2017-01-01
The purpose of this study was to assess the accuracy of fractional blood volume (vb) estimates in low-perfused and low-vascularized tissue using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). The results of different MRI methods were compared with histology to evaluate the accuracy of these methods under clinical conditions. vb was estimated by DCE-MRI using a 3D gradient echo sequence with k-space undersampling in five muscle groups in the hind leg of 9 female pigs. Two gadolinium-based contrast agents (CA) were used: a rapidly extravasating, extracellular, gadolinium-based, low-molecular-weight contrast agent (LMCA, gadoterate meglumine) and an extracellular, gadolinium-based, albumin-binding, slowly extravasating blood pool contrast agent (BPCA, gadofosveset trisodium). LMCA data were evaluated using the extended Tofts model (ETM) and the two-compartment exchange model (2CXM). The images acquired with administration of the BPCA were used to evaluate the accuracy of vb estimation with a bolus deconvolution technique (BD) and a method we call equilibrium MRI (EqMRI). The latter calculates the ratio of the magnitude of the relaxation rate change in the tissue curve at an approximate equilibrium state to the height of the same area of the arterial input function (AIF). Immunohistochemical staining with isolectin was used to label endothelium. A light microscope was used to estimate the fractional vascular area by relating the vascular region to the total tissue region (immunohistochemical vessel staining, IHVS). In addition, the percentage fraction of vascular volume was determined by multiplying the microvascular density (MVD) with the average estimated capillary lumen, π(d2)2, where d = 8μm is the assumed capillary diameter (microvascular density estimation, MVDE). Except for ETM values, highly significant correlations were found between most of the MRI methods investigated. In the cranial thigh, for example, the vb medians (interquartile range
Maiti, Moumita; Vinutha, H. A.; Sastry, Srikanth; Heussinger, Claus
2015-10-01
Using an athermal quasistatic simulation protocol, we study the distribution of free volumes in sheared hard-particle packings close to, but below, the random-close packing threshold. We show that under shear, and independent of volume fraction, the free volumes develop features similar to close-packed systems — particles self-organize in a manner as to mimick the isotropically jammed state. We compare athermally sheared packings with thermalized packings and show that thermalization leads to an erasure of these structural features. The temporal evolution in particular the opening-up and the closing of free-volume patches is associated with the single-particle dynamics, showing a crossover from ballistic to diffusive behavior.
Jung, Seung Chai; Choi, Seung Hong; Yeom, Jeong A.; Kim, Ji-Hoon; Ryoo, Inseon; Kim, Soo Chin; Shin, Hwaseon; Lee, A. Leum; Yun, Tae Jin; Park, Chul-Kee; Sohn, Chul-Ho; Park, Sung-Hye
2013-01-01
Purpose To compare the reproducibilities of manual and semiautomatic segmentation method for the measurement of normalized cerebral blood volume (nCBV) using dynamic susceptibility contrast-enhanced (DSC) perfusion MR imaging in glioblastomas. Materials and Methods Twenty-two patients (11 male, 11 female; 27 tumors) with histologically confirmed glioblastoma (WHO grade IV) were examined with conventional MR imaging and DSC imaging at 3T before surgery or biopsy. Then nCBV (means and standard deviations) in each mass was measured using two DSC MR perfusion analysis methods including manual and semiautomatic segmentation method, in which contrast-enhanced (CE)-T1WI and T2WI were used as structural imaging. Intraobserver and interobserver reproducibility were assessed according to each perfusion analysis method or each structural imaging. Interclass correlation coefficient (ICC), Bland-Altman plot, and coefficient of variation (CV) were used to evaluate reproducibility. Results Intraobserver reproducibilities on CE-T1WI and T2WI were ICC of 0.74–0.89 and CV of 20.39–36.83% in manual segmentation method, and ICC of 0.95–0.99 and CV of 8.53–16.19% in semiautomatic segmentation method, repectively. Interobserver reproducibilites on CE-T1WI and T2WI were ICC of 0.86–0.94 and CV of 19.67–35.15% in manual segmentation method, and ICC of 0.74–1.0 and CV of 5.48–49.38% in semiautomatic segmentation method, respectively. Bland-Altman plots showed a good correlation with ICC or CV in each method. The semiautomatic segmentation method showed higher intraobserver and interobserver reproducibilities at CE-T1WI-based study than other methods. Conclusion The best reproducibility was found using the semiautomatic segmentation method based on CE-T1WI for structural imaging in the measurement of the nCBV of glioblastomas. PMID:23950891
DEFF Research Database (Denmark)
Henriksen, Jens Henrik Sahl
2004-01-01
in haemodynamic and homoeostatic mechanisms in patients with cirrhosis. Infusion of oncotic material (preferably albumin) may prevent circulatory dysfunction during certain types of stress. Volume expansion in advanced cirrhosis is qualitatively and quantitively different from that of healthy subjects and those......Adequate size and distribution of the circulating medium are important for cardiovascular function, tissue oxygenation and fluid homoeostasis. Patients with cirrhosis have an abnormal distribution of increased blood volume, increased total vascular compliance and increased arterial compliance....... The pattern and temporal relations of plasma and blood volume expansion are important for pathophysiological, diagnostic and therapeutic purposes and depend highly on the type of load (water, saline, oncotic material, red blood cells). In some aspects patients with cirrhosis respond differently from healthy...
Kashima, Susumu; Nishihara, Minoru; Takemoto, Yoshihiro; Osawa, Toshihiko
1990-09-01
The laser scattering characteristics from tissue microvasculature have been made clear by means of theoretical and experimental approaches. Our results show that the integrated intensity of the power spectrum correlates linearly with the volume of red blood cells in a given tissue provided the average collision number (\\bar{m}) between photons and moving red blood cells is less than unity. Also, the integrated intensity of the power spectrum is proportional to tissue blood volume if the density of red blood cells in blood (hematocrit) is constant.
Institute of Scientific and Technical Information of China (English)
张超; 彭道黎; 党永峰; 智长贵
2013-01-01
The study was conducted to acquire the forest volume and its dynamic change in Three Gorges Reservoir Region quick-ly and efficiently .With the sixth and seventh of national cotinuous forest resources inventory and Landsat TM/ETM+ima-ges in 2003 and 2008 , the partial least squares regression model was generated and the predicting map of forest volume in Three Gorges Reservoir Region was constructed.Furthermore, the forest volume dynamic changes in this area were conduc-ted.The estimation precisions are 91.84%and 94.61%, respectively.The total forest volume of Three Gorges Reservoir Region are 94 446 687 and 104 314 340 m3 , respectively .The forest volume has a slow and steady arise from 2003 to 2008.The forest volume is mainly distributed at altitudes of 400 to 1 600 m and at slopes of 5-44.However, it is well dis-tributed at every slope aspect.%为了快速有效获取三峡库区森林蓄积量及其时空动态变化特征，基于第六次（2003年）和第七次（2008年）森林资源一类清查样地数据和TM/ETM＋遥感影像，利用偏最小二乘回归方法构建了森林蓄积量估测模型，估算了三峡库区森林蓄积量，定量分析了蓄积量的时空变化特征。利用预留独立样本对模型进行精度验证，两期模型的总体预测精度分别达到91．84％和94．61％；2003年和2008年三峡库区森林总蓄积量分别为94446687、104314340 m3，从2003年至2008年呈现缓慢增长的趋势；两期森林蓄积量在海拔400～1600 m、坡度5°～44°之间分布最多，在坡向上的分布较为均匀。
Energy Technology Data Exchange (ETDEWEB)
Hassein-bey-Larouci, A., E-mail: hasseinbey@yahoo.fr [Laboratoire Thermodynamique et Modélisation Moléculaire, Faculté de Chimie, Université des Sciences et de la Technologie Houari Boumediene, B.P. 32, El-Alia, 16111 Bab-Ezzouar, Alger (Algeria); Igoujilen, O.; Aitkaci, A. [Laboratoire Thermodynamique et Modélisation Moléculaire, Faculté de Chimie, Université des Sciences et de la Technologie Houari Boumediene, B.P. 32, El-Alia, 16111 Bab-Ezzouar, Alger (Algeria); Segovia, J.J.; Villamañán, M.A. [TERMOCAL Research Group, Escuela de Ingenierías Industriales, Universidad de Valladolid, Paseo del Cauce, 59, 47011 Valladolid (Spain)
2014-08-10
Highlights: • Many engineering applications require quantitative thermodynamic data of the fluids. • Excess properties of mixtures are important in the understanding of mixing process. • The results are used to explain the molecular interaction in the mixtures. - Abstract: Dynamic and kinematic viscosities, and densities of the ternary mixture {x_1 propanol + x_2 DMF + x_3 chloroform} and of the three corresponding binary systems have been measured at 293.15, 303.15, 313.15 and 323.15 K and atmospheric pressure. The thermophysical properties, viscosity deviations (Δη), kinematic viscosity (γ), excess Gibbs energies of activation of viscous flow (G*{sup E}) and excess molar volumes (V{sup E}) have been calculated from experimental values of dynamic viscosity, η, and density, ρ. The different results have been correlated by the Redlich–Kister equation for the binary mixtures and the Cibulka equation for equation for the ternary ones.
Suarez, Max J. (Editor); Takacs, Lawrence L.
1995-01-01
A detailed description of the numerical formulation of Version 2 of the ARIES/GEOS 'dynamical core' is presented. This code is a nearly 'plug-compatible' dynamics for use in atmospheric general circulation models (GCMs). It is a finite difference model on a staggered latitude-longitude C-grid. It uses second-order differences for all terms except the advection of vorticity by the rotation part of the flow, which is done at fourth-order accuracy. This dynamical core is currently being used in the climate (ARIES) and data assimilation (GEOS) GCMs at Goddard.
颈椎管容积和脊髓体积的MRI测量及其动态变化%Dynamic measurement of cervical spinal canal and cervical spinal cord volume
Institute of Scientific and Technical Information of China (English)
钱军; 申才良; 荆珏华; 田大胜
2009-01-01
目的 利用核磁共振测量正常人的颈椎管容积及脊髓的体积,并探讨其动态变化趋势.方法 选取正常人20名,排除退变、畸形和对扫描发生恐惧者4名,利用MRI无间隔梯度扰像回波序列方式分别扫描并测量过屈、中立、过伸位下各颈椎椎管容积和脊髓的体积,并进行统计学分析.结果 过屈、中立、过伸三种体位下正常人的颈椎管容积改变趋势为V过屈V中立V过伸,且三个体位下的容积差异有显著性(P0.05);过屈、中立和过伸位下脊髓的体积差异均无统计学意义(P>0.05),颈段脊髓的体积约10.69±0.56cm3.结论 颈椎由过屈向过伸动态变化过程中,颈椎管的容积是逐渐减小的,且颈椎管容积的改变主要发生在颈3～颈7节段;但颈段脊髓的体积是固定不变的,脊髓的形态和在椎管内的位置是变化的.%Objectives To measure the cervical spinal canal and cervical spinal cord volume of healthy people during MRI,and also to evaluate the dynamic changes of the cervical spinal canal and cervical spinal cord volume with the angle change of the cervical vertebrae. Methods Twenty healthy people are chosen to experiment,and four individuals of all are excluded because of degeneration,deformity or in fear of the scan. The remaining 16 individuals are conducted MRI scan. Last,we analyze the conclusions and evaluate their dynamic changes. Results The volume of the cervical spinal canal reduced gradually. The volume was larger in flexion position than in the central position,and the volume was larger in central position than in the extension position,and al-so they had a significant difference (P0.05),the mean volume of cer-vical spinal cord were about 10.69±0.56cm3. Conclusion The volume of the cervical spinal canal decreases gradually with increasing extension angle,but the volume of the spinal cord is always the same size with changing the angle of cervical vertebrae,and the shape and location of the spinal
Directory of Open Access Journals (Sweden)
Sovenko S.P.
2012-12-01
Full Text Available Analysed and systematized information in relation to the volume of competition practice and facilities of different primary orientation of jumpers in length and triple in the process of long-term preparation. The expert questioning is conducted 16 trainers. The documents of planning of training process are analysed, the analysis of diaries of sportsmen is carried out (n=22. The volume of competition practice of sportsmen and facilities of training of different primary orientation is certain. The results of analysis in relation to the construction of training process are reflected by the leading trainers of Ukraine on track-and-field. An approach classification of facilities of training taking into account the specific of training process of sportsmen is presented. It is set that the volume of facilities of general preparation is most on the initial stages of long-term perfection, then stabilized on the stages specialized base and preparations to higher achievements and a few diminishes on maximal implementation of individual possibilities and maintainance of higher sporting trade phases. It is related to diminishing of duration of the general preparatory stages of annual preparation.
Gover, A. Rod; Waldron, Andrew
2017-09-01
We develop a universal distributional calculus for regulated volumes of metrics that are suitably singular along hypersurfaces. When the hypersurface is a conformal infinity we give simple integrated distribution expressions for the divergences and anomaly of the regulated volume functional valid for any choice of regulator. For closed hypersurfaces or conformally compact geometries, methods from a previously developed boundary calculus for conformally compact manifolds can be applied to give explicit holographic formulæ for the divergences and anomaly expressed as hypersurface integrals over local quantities (the method also extends to non-closed hypersurfaces). The resulting anomaly does not depend on any particular choice of regulator, while the regulator dependence of the divergences is precisely captured by these formulæ. Conformal hypersurface invariants can be studied by demanding that the singular metric obey, smoothly and formally to a suitable order, a Yamabe type problem with boundary data along the conformal infinity. We prove that the volume anomaly for these singular Yamabe solutions is a conformally invariant integral of a local Q-curvature that generalizes the Branson Q-curvature by including data of the embedding. In each dimension this canonically defines a higher dimensional generalization of the Willmore energy/rigid string action. Recently, Graham proved that the first variation of the volume anomaly recovers the density obstructing smooth solutions to this singular Yamabe problem; we give a new proof of this result employing our boundary calculus. Physical applications of our results include studies of quantum corrections to entanglement entropies.
Demerdash, N. A. O.; Nehl, T. W.
1979-01-01
A description and user's guide of the computer program developed to simulate the dynamics of an electromechanical actuator for aerospace applications are presented. The effects of the stator phase currents on the permanent magnets of the rotor are examined. The voltage and current waveforms present in the power conditioner network during the motoring, regenerative braking, and plugging modes of operation are presented and discussed.
The dynamic behavior of sliding tribosystems in unstable operating conditions
Postaru, A.; Postaru, Ghe; Ceban, V.; Spânu, C.; Stoicev, P.
2017-02-01
The paper addresses the issue of the influence that the law of friction has on the dynamic behavior of the mechanical system that interacts with a tribosystem. The emergence of certain nonlinearities of higher order into the law of friction leads to an intensification of the dissipative process and to tribosystem destabilization. Consequently, friction excited self-oscillations are generated into the elements of the mechanical system with a wide spectrum of frequencies, sustained from the external source of energy. The theoretical and experimental modelling of the dissipative process and of the generation of is based on the frictional harmonic oscillator that interacts with the tribosystem. The oscillator is used as a sensitive element to the fluctuations of the frictional force and as a measure of the dissipated energy. Starting from the model, the elaboration of a method and of devices for experimental research provided the opportunity to study the behavior of the tribosystem in unstable operating
Nonlinear radiation pressure dynamics in an optomechanical crystal
Krause, Alex G; Ludwig, Max; Safavi-Naeini, Amir H; Chan, Jasper; Marquardt, Florian; Painter, Oskar
2015-01-01
Utilizing a silicon nanobeam optomechanical crystal, we investigate the attractor diagram arising from the radiation pressure interaction between a localized optical cavity at $\\lambda = 1552$nm and a mechanical resonance at $\\omega/2\\pi = 3.72$GHz. At a temperature of $T \\approx 10$K, highly nonlinear driving of mechanical motion is observed via continuous wave optical pumping. Introduction of a time-dependent (modulated) optical pump is used to steer the system towards an otherwise inaccessible dynamically stable attractor in which mechanical self-oscillation occurs for an optical pump red-detuned from the cavity resonance. An analytical model incorporating thermo-optic effects due to optical absorption heating is developed, and found to accurately predict the measured device behavior.
1984-01-01
methods and procedures should be continuously improved and adapted to the latest state of the art . 3.3 Improving the Convergence Convergence improving...1972 System Identification of Vibrating 0 Structures, ASME. State-of-the- art of system identification of aerospace structures. 11. A. BERMAN 1975...129. Non linear dynamics by mode superposition. 5. S. IDELSOHN and A. CARDONA 1982 Cuaderno No 16 ed. by Comite Argentino de Transferencia de Calor y
Demerdash, N. A. O.; Nehl, T. W.
1979-01-01
The development, fabrication and evaluation of a prototype electromechanical actuator (EMA) is discussed. Application of the EMA as a motor for control surfaces in aerospace flight is examined. A mathematical model of the EMA is developed for design optimization. Nonlinearities which complicate the mathematical model are discussed. The dynamics of the EMA from the underlying physical principles are determined and a discussion of similating the control logic by means of equivalent boolean expressions is presented.
1998-07-30
8217 1 Dipartimento di Chimica dell’UniversitY, Perugia, Italy 2 Instituto Pluridisciplinar, Universidad Complutense , Madrid , Spain 1 Introduction...Jim~nez, A. GonzAlez Urefia Unidad de Laseres y Haces Moleculares. Universidad Complutense de Madrid . Spain. The spectroscopy and dynamics of We have...continued) 17:00 - 18:30 POSTER SESSION MB - P Chair: A. Gonzalez-Urena ( Madrid ) Observation and Spectroscopy of Metastable 04 D.S. Peterka, M. Ahmed
DEFF Research Database (Denmark)
Thomsen, H; Steffensen, E; Larsson, Elna-Marie
2012-01-01
technique arterial spin labelling (ASL) presently provides measurement only of cerebral blood flow (CBF), which has not been widely used in human brain tumor studies. Purpose: To assess if measurement of blood flow is comparable with measurement of blood volume in human biopsy-proven gliomas obtained by DSC......, and glioblastomas. Results: rCBF and rCBV measurements obtained with the maximum perfusion method were correlated when normalized to white matter (r ¼ 0.60) and to the cerebellum (r ¼ 0.49). Histogram analyses of rCBF and rCBV showed that mean and median values as well as skewness and peak position were correlated......-MRI using two different regions for normalization and two different measurement approaches. Material and Methods: Retrospective study of 61 patients with different types of gliomas examined with DSC perfusion MRI. Regions of interest (ROIs) were placed in tumor portions with maximum perfusion on rCBF and r...
Energy Technology Data Exchange (ETDEWEB)
Vaidya, R.U.; Song, S.G.; Zurek, A.K.; Gray, G.T. III
1995-09-01
Static and Dynamic mechanical tests, and microstructural examinations performed on a SiC particle reinforced 6061-Al matrix composite indicated that particle cracking significantly affected the strength, strain hardening, and failure mechanism of the composite. Cracks were observed to nucleate and propagate on stacking faults and interfaces between the various phases within the reinforcing SiC particles. Planar defects were the predominant artifacts seen in the SiC particles. Partial dislocations were also observed bounding the stacking faults within the reinforcement phase.
Directory of Open Access Journals (Sweden)
Fernando S. Guimarães
2012-04-01
Full Text Available Contextualização: Embora a fisioterapia respiratória seja considerada fundamental para o tratamento de pacientes hipersecretivos, há poucas evidências acerca de seus efeitos fisiológicos e terapêuticos em indivíduos com bronquiectasia. Objetivos: Avaliar os efeitos fisiológicos imediatos da ELTGOL e do Flutter® nos volumes pulmonares dinâmicos e estáticos em pacientes com bronquiectasia e, secundariamente, determinar o efeito dessas técnicas na remoção de secreção brônquica. Métodos: Participaram do estudo pacientes com diagnóstico clínico e radiológico de bronquiectasia. Os pacientes foram submetidos a três intervenções de forma randomizada e com um intervalo (washout de uma semana entre elas. Inicialmente os pacientes inalaram dois jatos de 100µcg de salbutamol. Após 5 minutos de tosse iniciais e após 5 minutos de tosse que sucederam o protocolo controle e as intervenções (ELTGOL e Flutter®, os pacientes realizaram as avaliações dos volumes pulmonares dinâmicos e estáticos por meio da espirometria e pletismografia corporal. A secreção expectorada foi coletada durante as intervenções e durante a segunda série de tosse, sendo quantificada por meio de seu peso seco. Resultados: Foram avaliados dez pacientes, dois do sexo masculino e oito do sexo feminino (média de idade de 55,9±18,1 anos. Após a utilização do Flutter® e da ELTGOL, observou-se diminuição significativa do volume residual (VR, da capacidade residual funcional (CRF e da CPT (pBackground: Although respiratory physical therapy is considered fundamental in the treatment of hypersecretive patients, there is little evidence of its physiological and therapeutic effects in bronchiectasis patients. Objective: To evaluate the acute physiological effects of ELTGOL and Flutter VRP1® in dynamic and static lung volumes in patients with bronchiectasis and, secondarily, to study the effect of these techniques in sputum elimination. Methods: Patients
Focks, D A; Kloter, K O; Carmichael, G T
1987-05-01
The efficacy of sequential, ultra-low volume ground aerosol applications of malathion at current U.S. label rates was evaluated as an emergency control measure for adult populations of Aedes aegypti (L.) in New Orleans, Louisiana. Replicates of 11 sequential aerosol treatments applied 12 hr apart during a 5.5-day period reduced mean adult captures and oviposition rates during the treatment period 73% and 75%, respectively. We hypothesize that oviposition was not completely suppressed because females with a developing egg burden remained sequestered during treatment periods or were more tolerant to the pesticide. We further concluded that adults could not be totally suppressed because of continued emergence. After treatment, adult densities recovered to pretreatment and control levels within approximately 1 week. A simulation study of the results suggested that, under the conditions of closely spaced housing and abundant vegetation that is typical of much of New Orleans, a single aerosol killed an average of 88% of the males and only 30% of the females present.
Institute of Scientific and Technical Information of China (English)
吴威; 曹有挥; 梁双波; 肖琛
2011-01-01
Taking 16 cities in the Yangtze River Delta as the object of study,this paper analyzes the freight volume dynamics and influencing mechanism since the mid-1980s from the aspects of quantitative growth,evolution in spatial pattern,spatial competition and pattern change of container cargo flow.The results show that,both the freight volume,freight turnover and the transportation range in the Yangtze River Delta have increased by a large margin and the regional spatial structure of freight volume has a complicated change with the rapid economic growth during the past 20 years.The centralization pattern is obvious in these years,Shanghai,Nanjing,Hangzhou,Ningbo is prominent in freight volume,but the distribution of freight volume tend to equilibrium as a whole,meanwhile,the freight and production place appeared some isolated situation.The container cargo flow in the Yangtze River Delta is highly competitive.Shanghai initially established the position as the central hub port and Ningbo port has the obvious advantages of spatial agglomeration,but the general spatial agglomeration function of container port system is not prominent.The driving mechanism of freight dynamics is mainly influenced by economic globalization,global supply chain and manufacturing paradigm shift from the macroscopic level,while from the middle and microcosmic level,it was mainly affected by regional economic systems and integrated transport costs,regional segmentation and traffic management system,etc.%以长三角地区16市为研究对象,从数量增长、空间格局变动及集装箱运输的空间竞争与格局演变等方面对长三角地区20世纪80年代中期以来货运量动态变化及其影响机制进行了分析。结果表明：随着经济的快速增长,长三角地区货运量、货运周转量及平均运距均大幅增长,货运量地域空间结构变动复杂,总体上极化特征突出,在时间演化上趋于区域均衡化,但同时货运量与生产地出现了一定
Institute of Scientific and Technical Information of China (English)
许炜敏; 陈友飞; 林广发; 陈明华
2011-01-01
树木的生长不仅受到自身遗传因素的影响而且还受外界环境条件的影响.以杉木为例,基于实测数据建立的蓄积量随林龄增长的生长模型以及影响林木生长的立地因子,以实现林分中的杉木林蓄积量可视化表达.在3D Max中构建了杉木三维形态几何模型,结合杉木生长模型与形态模型,采用AE+VB.NET编程,实现了基于ArcScene的杉木林蓄积量动态可视化,能直观地反映杉木林蓄积量随立地条件和生长模型的生长状况,对于林业生产信息化和林场的管理、经营和决策具有很大的实用价值.%The growth of the trees is influenced not only by genetic factors and also by extemal environmental conditions. Taking Chinese firs for example, this paper, based on measured data, established the growth model of volume correlated to the stand age and site factors that influence the growth of trees. The research is helpful to realize the visualization of Chinesefir stand volume.Three-dimensional geometric model of Chinese fir is constructed through 3D Max. On the basis of the growth model and the configuration model of Chinese fir, the dynamic visualization d Chinese fir volume was realized based on ArcScene by adopting AE + VB. NET programming. It is possible to directly manifest the growth conditions of Chinese fir volume according to the site conditions and growth model and is of high practical value to forestry production information, the management, operation and strategy of the forest farm.
Sparse PDF Volumes for Consistent Multi-Resolution Volume Rendering
Sicat, Ronell Barrera
2014-12-31
This paper presents a new multi-resolution volume representation called sparse pdf volumes, which enables consistent multi-resolution volume rendering based on probability density functions (pdfs) of voxel neighborhoods. These pdfs are defined in the 4D domain jointly comprising the 3D volume and its 1D intensity range. Crucially, the computation of sparse pdf volumes exploits data coherence in 4D, resulting in a sparse representation with surprisingly low storage requirements. At run time, we dynamically apply transfer functions to the pdfs using simple and fast convolutions. Whereas standard low-pass filtering and down-sampling incur visible differences between resolution levels, the use of pdfs facilitates consistent results independent of the resolution level used. We describe the efficient out-of-core computation of large-scale sparse pdf volumes, using a novel iterative simplification procedure of a mixture of 4D Gaussians. Finally, our data structure is optimized to facilitate interactive multi-resolution volume rendering on GPUs.
Sparse PDF Volumes for Consistent Multi-Resolution Volume Rendering.
Sicat, Ronell; Krüger, Jens; Möller, Torsten; Hadwiger, Markus
2014-12-01
This paper presents a new multi-resolution volume representation called sparse pdf volumes, which enables consistent multi-resolution volume rendering based on probability density functions (pdfs) of voxel neighborhoods. These pdfs are defined in the 4D domain jointly comprising the 3D volume and its 1D intensity range. Crucially, the computation of sparse pdf volumes exploits data coherence in 4D, resulting in a sparse representation with surprisingly low storage requirements. At run time, we dynamically apply transfer functions to the pdfs using simple and fast convolutions. Whereas standard low-pass filtering and down-sampling incur visible differences between resolution levels, the use of pdfs facilitates consistent results independent of the resolution level used. We describe the efficient out-of-core computation of large-scale sparse pdf volumes, using a novel iterative simplification procedure of a mixture of 4D Gaussians. Finally, our data structure is optimized to facilitate interactive multi-resolution volume rendering on GPUs.
Institute of Scientific and Technical Information of China (English)
杜玉昆; 王瑞和; 倪红坚
2009-01-01
发展新型破岩钻井技术对于促进油气田高效开发具有重要意义,高压水射流是提高破岩钻井效率的一个重要手段,脉冲射流是一种高效射流形式.为了充分利用井底水力能量,提出了一种环空流体吸入式脉冲射流的技术构想.基于自激振荡原理设计了相应射流调制工具,并对工具的流场和动力学特性进行了大涡模拟研究.研究结果分析揭示了环空流体吸入式自激振荡脉冲射流调制的机理,并发现合理的水力结构可以在振荡腔内实现局部负压,使得环空流体被吸入,参与调制生成高效脉冲射流.与非吸入式脉冲射流相比,吸入式脉冲射流振荡更加剧烈,破岩能力更强.研究结果得到了实验验证,为实际钻井工具的研制和相关工艺技术的开发提供了依据.%It is of great significance that developing new rock breaking drilling technology to promote efficient exploit of oil field. High pressure water jet drilling technology is an important method to promote the rock breaking drilling efficiency, and pulsed water jet is such a kind of high efficiency water jet. In order to take full advantage of hydraulic energy in bottom hole, a concept of new type of pulsed water jet drawing in annulus flow, is put forward. The pulsed water jet modulation tool is designed based on the self-exciting principle, and the large eddy simulation is adopted to simulate the flow field and the dynamic characteristics in this tool. This simulation shows the modulation mechanism of self-exciting pulsed water jet drawing in annulus flow. Partial negative pressure could be achieved in the oscillating cavity if the reasonable hydraulic structure is applied. The negative pressure formed in the drawing entrance of the oscillating cavity provides assurance to automatically draw enough fluid into annulus flow, which takes part in modulating the efficient pulsed water jet. The amplitude is larger and the rock breaking capacity of
Gover, A Rod
2016-01-01
For any conformally compact manifold with hypersurface boundary we define a canonical renormalized volume functional and compute an explicit, holographic formula for the corresponding anomaly. For the special case of asymptotically Einstein manifolds, our method recovers the known results. The anomaly does not depend on any particular choice of regulator, but the coefficients of divergences do. We give explicit formulae for these divergences valid for any choice of regulating hypersurface; these should be relevant to recent studies of quantum corrections to entanglement entropies. The anomaly is expressed as a conformally invariant integral of a local Q-curvature that generalizes the Branson Q-curvature by including data of the embedding. In each dimension this canonically defines a higher dimensional generalization of the Willmore energy/rigid string action. We show that the variation of these energy functionals is exactly the obstruction to solving a singular Yamabe type problem with boundary data along the...
Energy Technology Data Exchange (ETDEWEB)
Budjan, Johannes, E-mail: Johannes.Budjan@umm.de [Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim—Heidelberg University, Mannheim (Germany); Ong, Melissa; Riffel, Philipp [Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim—Heidelberg University, Mannheim (Germany); Morelli, John N. [Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD (United States); Michaely, Henrik J.; Schoenberg, Stefan O.; Haneder, Stefan [Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim—Heidelberg University, Mannheim (Germany)
2014-11-15
Highlights: • We examined the influence of different clinically used contrast agents on the image quality of a new sequence called CDT-VIBE for dynamic MRI of the liver. • CDT-VIBE is a robust sequence for clinical routine as it provides good image quality regardless of the utilized contrast agent. • In average, more than 3 hepatic arterial dominant phases are acquired with the CDT-VIBE sequence regardless of the contrast agent. - Abstract: Purpose: CAIPIRINHA-Dixon-TWIST (CDT)-VIBE is a robust method for abdominal magnetic resonance imaging providing both high spatial and high temporal resolution. The purpose of this study was to examine the influence of different gadolinium based contrast agents (GBCA) on image quality (IQ) with CDT-VIBE. Materials and methods: In this IRB-approved, retrospective, inter-individual comparison study, 86 patients scanned at 3T were included. Within 28 s, 14 high-resolution 3D datasets were acquired using CDT-VIBE. 37 patients received 0.1 mmol/kg gadoterate meglumine, 28 patients 0.1 mmol/kg gadobutrol, and 19 patients 0.1 mL/kg gadoxetic acid. Two blinded, board-certified radiologists assessed the image quality on a 5 point scale, as well as the number of hepatic arterial dominant (HAD) phases. Results: Regardless of the GBCA utilized, CDT-VIBE resulted in good IQ in terms of best IQ achieved among all 14 datasets (gadobutrol 4.3, gadoterate meglumine 3.9, gadoxetic acid 3.7). With respect to worst IQ, the three groups showed statistically significant differences with gadobutrol receiving the highest rating (3.6) and gadoxetic acid the lowest (2.4) (gadoterate meglumine 3.0; 0.0014 < p < 0.0485). No statistically significant differences were found in the mean number of acquired HAD phases (gadobutrol 3.4, gadoterate meglumine 3.9, gadoxetic acid 3.1; 0.18 < p < 0.57). Conclusion: Different gadolinium-based contrast agents can be utilized for dynamic liver imaging with CDT-VIBE resulting in good image quality.
Liang, Anita D. (Technical Monitor); Shapiro, Wilbur; Aggarwal, Bharat
2004-01-01
The objectives of the program were to develop computational fluid dynamics (CFD) codes and simpler industrial codes for analyzing and designing advanced seals for air-breathing and space propulsion engines. The CFD code SCISEAL is capable of producing full three-dimensional flow field information for a variety of cylindrical configurations. An implicit multidomain capability allows the division of complex flow domains to allow optimum use of computational cells. SCISEAL also has the unique capability to produce cross-coupled stiffness and damping coefficients for rotordynamic computations. The industrial codes consist of a series of separate stand-alone modules designed for expeditious parametric analyses and optimization of a wide variety of cylindrical and face seals. Coupled through a Knowledge-Based System (KBS) that provides a user-friendly Graphical User Interface (GUI), the industrial codes are PC based using an OS/2 operating system. These codes were designed to treat film seals where a clearance exists between the rotating and stationary components. Leakage is inhibited by surface roughness, small but stiff clearance films, and viscous pumping devices. The codes have demonstrated to be a valuable resource for seal development of future air-breathing and space propulsion engines.
Advances in heat transfer volume 21
Hartnett †, James P; Cho, Young I
1991-01-01
This volume in a series on heat transfer covers the modelling of the dynamics of turbulent transport processes, supercritical pressures, hydrodynamics, mass transfer near rotating surfaces, lost heat in entropy and the mechanics of heat transfer in a multifluid bubbling pool. Other related titles are "Advances in Heat Transfer", volumes 18, 19 and 20.
Institute of Scientific and Technical Information of China (English)
井丽龙; 张文平; 明平剑; 付丽荣; 刘晓刚
2015-01-01
为探究Timoshenko梁模型数值计算方法,开展了基于有限体积法的Timoshenko梁数值计算方法研究. 利用有限体积法对考虑剪切变形的梁进行了离散,并进行了静力学分析和动力学分析,通过几个经典算例将此方法所得到的数值解与解析解及有限元解进行了对比,结果证明,有限体积法有较高精度. 与此同时利用有限体积法离散Timoshenko梁时当梁为细长梁时不存在剪切自锁现象. 有限体积法可以应用于Timoshenko梁模型静力弯曲分析、固有特性和动力响应分析.%In order to explore a numerical simulation method based on the Timoshenko beam model, a study was done on beam numerical simulation using the Timoshenko beam model, based on the finite volume method ( FVM) . In order to examine the beam's shear deformation, the beam model was discretized by FVM, and static and dynamic analyses were conducted. After first calculating some typical examples, the derived numerical results and the analyt-ic solutions with FVM, a comparison was made with the solution by FVM. It is shown that FVM provides high preci-sion analysis, with no shear-locking phenomenon for thin and long beams when discretizing Timoshenko beam based on FVM. This validates FVM for analyzing Timoshenko beam static bending, inherent characteristics, and dynamic response problems.
Birkhoff, George D
1927-01-01
His research in dynamics constitutes the middle period of Birkhoff's scientific career, that of maturity and greatest power. -Yearbook of the American Philosophical Society The author's great book€¦is well known to all, and the diverse active modern developments in mathematics which have been inspired by this volume bear the most eloquent testimony to its quality and influence. -Zentralblatt MATH In 1927, G. D. Birkhoff wrote a remarkable treatise on the theory of dynamical systems that would inspire many later mathematicians to do great work. To a large extent, Birkhoff was writing about his o
A Finite Volume Scheme on the Cubed Sphere Grid
Putman, William M.; Lin, S. J.
2008-01-01
The performance of a multidimensional finite-volume scheme for global atmospheric dynamics is evaluated on the cubed-sphere geometry. We will explore the properties of the finite volume scheme through traditional advection and shallow water test cases. Baroclinic evaluations performed via a recently developed deterministic initial value baroclinic test case from Jablonowski and Williamson that assesses the evolution of an idealized baroclinic wave in the Northern Hemisphere for a global 3-dimensional atmospheric dynamical core. Comparisons will be made when available to the traditional latitude longitude discretization of the finite-volume dynamical core, as well as other traditional gridpoint and spectral formulations for atmospheric dynamical cores.
The Shock and Vibration Digest. Volume 13. Number 2
1981-02-01
whierln Iunstability damae a wel a th exprimnta reultsis ecomened. variouas usual pitches and arrangements are tested. Critical velocities are...and Centro Atomico Bariloche Oscillation, Beams (CNEA), Rio Negro , Argentina, J. Acoust. Soc. A method of determination of self oscillation and shape
Energy Technology Data Exchange (ETDEWEB)
Server, Andres; Nakstad, Per H. [Oslo University Hospital-Ullevaal, Section of Neuroradiology, Department of Radiology and Nuclear Medicine, Oslo (Norway); University of Oslo, Oslo (Norway); Orheim, Tone E.D. [Oslo University Hospital, Interventional Centre, Oslo (Norway); Graff, Bjoern A. [Oslo University Hospital-Ullevaal, Department of Radiology and Nuclear Medicine, Oslo (Norway); Josefsen, Roger [Oslo University Hospital-Ullevaal, Department of Neurosurgery, Oslo (Norway); Kumar, Theresa [Oslo University Hospital-Ullevaal, Department of Pathology, Oslo (Norway)
2011-05-15
Conventional magnetic resonance (MR) imaging has limited capacity to differentiate between glioblastoma multiforme (GBM) and metastasis. The purposes of this study were: (1) to compare microvascular leakage (MVL), cerebral blood volume (CBV), and blood flow (CBF) in the distinction of metastasis from GBM using dynamic susceptibility-weighted contrast-enhanced perfusion MR imaging (DSC-MRI), and (2) to estimate the diagnostic accuracy of perfusion and permeability MR imaging. A prospective study of 61 patients (40 GBMs and 21 metastases) was performed at 3 T using DSC-MRI. Normalized rCBV and rCBF from tumoral (rCBVt, rCBFt), peri-enhancing region (rCBVe, rCBFe), and by dividing the value in the tumor by the value in the peri-enhancing region (rCBVt/e, rCBFt/e), as well as MVL were calculated. Hemodynamic and histopathologic variables were analyzed statistically and Spearman/Pearson correlations. Receiver operating characteristic curve analysis was performed for each of the variables. The rCBVe, rCBFe, and MVL were significantly greater in GBMs compared with those of metastases. The optimal cutoff value for differentiating GBM from metastasis was 0.80 which implies a sensitivity of 95%, a specificity of 92%, a positive predictive value of 86%, and a negative predictive value of 97% for rCBVe ratio. We found a modest correlation between rCBVt and rCBFt ratios. MVL measurements in GBMs are significantly higher than those in metastases. Statistically, both rCBVe, rCBVt/e and rCBFe, rCBFt/e were useful in differentiating between GBMs and metastases, supporting the hypothesis that perfusion MR imaging can detect infiltration of tumor cells in the peri-enhancing region. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Server, Andres; Nakstad, Per H. [Oslo University Hospital-Ullevaal, Section of Neuroradiology, Department of Radiology and Nuclear Medicine, Oslo (Norway); University of Oslo, Oslo (Norway); Graff, Bjoern A. [Oslo University Hospital-Ullevaal, Department of Radiology and Nuclear Medicine, Oslo (Norway); Orheim, Tone E.D.; Gadmar, Oeystein B. [Oslo University Hospital, Interventional Centre, Oslo (Norway); Schellhorn, Till [Oslo University Hospital-Ullevaal, Section of Neuroradiology, Department of Radiology and Nuclear Medicine, Oslo (Norway); Josefsen, Roger [Oslo University Hospital-Ullevaal, Department of Neurosurgery, Oslo (Norway)
2011-06-15
To assess the diagnostic accuracy of microvascular leakage (MVL), cerebral blood volume (CBV) and blood flow (CBF) values derived from dynamic susceptibility-weighted contrast-enhanced perfusion MR imaging (DSC-MR imaging) for grading of cerebral glial tumors, and to estimate the correlation between vascular permeability/perfusion parameters and tumor grades. A prospective study of 79 patients with cerebral glial tumors underwent DSC-MR imaging. Normalized relative CBV (rCBV) and relative CBF (rCBF) from tumoral (rCBVt and rCBFt), peri-enhancing region (rCBVe and rCBFe), and the value in the tumor divided by the value in the peri-enhancing region (rCBVt/e and rCBFt/e), as well as MVL, expressed as the leakage coefficient K{sub 2} were calculated. Hemodynamic variables and tumor grades were analyzed statistically and with Pearson correlations. Receiver operating characteristic (ROC) curve analyses were also performed for each of the variables. The differences in rCBVt and the maximum MVL (MVL{sub max}) values were statistically significant among all tumor grades. Correlation analysis using Pearson was as follows: rCBVt and tumor grade, r = 0.774; rCBFt and tumor grade, r = 0.417; MVL{sub max} and tumor grade, r = 0.559; MVL{sub max} and rCBVt, r = 0.440; MVL{sub max} and rCBFt, r = 0.192; and rCBVt and rCBFt, r = 0.605. According to ROC analyses for distinguishing tumor grade, rCBVt showed the largest areas under ROC curve (AUC), except for grade III from IV. Both rCBVt and MVL{sub max} showed good discriminative power in distinguishing all tumor grades. rCBVt correlated strongly with tumor grade; the correlation between MVL{sub max} and tumor grade was moderate. (orig.)
1991-01-01
Dynamical Bifurcation Theory is concerned with the phenomena that occur in one parameter families of dynamical systems (usually ordinary differential equations), when the parameter is a slowly varying function of time. During the last decade these phenomena were observed and studied by many mathematicians, both pure and applied, from eastern and western countries, using classical and nonstandard analysis. It is the purpose of this book to give an account of these developments. The first paper, by C. Lobry, is an introduction: the reader will find here an explanation of the problems and some easy examples; this paper also explains the role of each of the other paper within the volume and their relationship to one another. CONTENTS: C. Lobry: Dynamic Bifurcations.- T. Erneux, E.L. Reiss, L.J. Holden, M. Georgiou: Slow Passage through Bifurcation and Limit Points. Asymptotic Theory and Applications.- M. Canalis-Durand: Formal Expansion of van der Pol Equation Canard Solutions are Gevrey.- V. Gautheron, E. Isambe...
Gladwell, Graham ML
2011-01-01
The papers in this volume present an overview of the general aspects and practical applications of dynamic inverse methods, through the interaction of several topics, ranging from classical and advanced inverse problems in vibration, isospectral systems, dynamic methods for structural identification, active vibration control and damage detection, imaging shear stiffness in biological tissues, wave propagation, to computational and experimental aspects relevant for engineering problems.
Analog circuit design designing dynamic circuit response
Feucht, Dennis
2010-01-01
This second volume, Designing Dynamic Circuit Response builds upon the first volume Designing Amplifier Circuits by extending coverage to include reactances and their time- and frequency-related behavioral consequences.
Finite Volumes for Complex Applications VII
Ohlberger, Mario; Rohde, Christian
2014-01-01
The methods considered in the 7th conference on "Finite Volumes for Complex Applications" (Berlin, June 2014) have properties which offer distinct advantages for a number of applications. The second volume of the proceedings covers reviewed contributions reporting successful applications in the fields of fluid dynamics, magnetohydrodynamics, structural analysis, nuclear physics, semiconductor theory and other topics. The finite volume method in its various forms is a space discretization technique for partial differential equations based on the fundamental physical principle of conservation. Recent decades have brought significant success in the theoretical understanding of the method. Many finite volume methods preserve further qualitative or asymptotic properties, including maximum principles, dissipativity, monotone decay of free energy, and asymptotic stability. Due to these properties, finite volume methods belong to the wider class of compatible discretization methods, which preserve qualitative propert...
Ovarian volume throughout life
DEFF Research Database (Denmark)
Kelsey, Thomas W; Dodwell, Sarah K; Wilkinson, A Graham
2013-01-01
cancer. To date there is no normative model of ovarian volume throughout life. By searching the published literature for ovarian volume in healthy females, and using our own data from multiple sources (combined n=59,994) we have generated and robustly validated the first model of ovarian volume from...... to about 2.8 mL (95% CI 2.7-2.9 mL) at the menopause and smaller volumes thereafter. Our model allows us to generate normal values and ranges for ovarian volume throughout life. This is the first validated normative model of ovarian volume from conception to old age; it will be of use in the diagnosis...
Energy Technology Data Exchange (ETDEWEB)
Chin, E; Hoppe, R; Million, L; Loo, B; Koong, A; Xing, L; Hsu, A; Fahimian, B [Stanford University, Stanford, CA (United States); Otto, K [University of British Columbia, Vancouver, BC (Canada)
2015-06-15
Purpose: Integration of coordinated robotic table motion with inversely-planned arc delivery has the potential to resolve table-top delivery limitations of large-field treatments such as Total Body Irradiation (TBI), Total Lymphoid Irradiation (TLI), and Cranial-Spinal Irradiation (CSI). We formulate the foundation for Trajectory Modulated Arc Therapy (TMAT), and using Varian Developer Mode capabilities, experimentally investigate its practical implementation for such techniques. Methods: A MATLAB algorithm was developed for inverse planning optimization of the table motion, MLC positions, and gantry motion under extended-SSD geometry. To maximize the effective field size, delivery trajectories for TMAT TBI were formed with the table rotated at 270° IEC and dropped vertically to 152.5cm SSD. Preliminary testing of algorithm parameters was done through retrospective planning analysis. Robotic delivery was programmed using custom XML scripting on the TrueBeam Developer Mode platform. Final dose was calculated using the Eclipse AAA algorithm. Initial verification of delivery accuracy was measured using OSLDs on a solid water phantom of varying thickness. Results: A comparison of DVH curves demonstrated that dynamic couch motion irradiation was sufficiently approximated by static control points spaced in intervals of less than 2cm. Optimized MLC motion decreased the average lung dose to 68.5% of the prescription dose. The programmed irradiation integrating coordinated table motion was deliverable on a TrueBeam STx linac in 6.7 min. With the couch translating under an open 10cmx20cm field angled at 10°, OSLD measurements along the midline of a solid water phantom at depths of 3, 5, and 9cm were within 3% of the TPS AAA algorithm with an average deviation of 1.2%. Conclusion: A treatment planning and delivery system for Trajectory Modulated Arc Therapy of extended volumes has been established and experimentally demonstrated for TBI. Extension to other treatment
DEFF Research Database (Denmark)
Mogensen, O.; Sørensen, Flemming Brandt; Bichel, P.
1999-01-01
We evaluated the following nine parameters with respect to their prognostic value in females with endometrial cancer: four stereologic parameters [mean nuclear volume (MNV), nuclear volume fraction, nuclear index and mitotic index], the immunohistochemical expression of cancer antigen (CA125...
Videotapes and Movies on Fluid Dynamics and Fluid Machines
Carr, Bobbie; Young, Virginia E.
1996-01-01
Chapter 17 of Handbook of Fluid Dynamics and Fluid Machinery: Experimental and Computational Fluid Dynamics, Volume 11. A list of videorecordings and 16mm motion pictures about Fluid Dynamics and Fluid Machines.
Programmatic methods for addressing contaminated volume uncertainties.
Energy Technology Data Exchange (ETDEWEB)
DURHAM, L.A.; JOHNSON, R.L.; RIEMAN, C.R.; SPECTOR, H.L.; Environmental Science Division; U.S. ARMY CORPS OF ENGINEERS BUFFALO DISTRICT
2007-01-01
Accurate estimates of the volumes of contaminated soils or sediments are critical to effective program planning and to successfully designing and implementing remedial actions. Unfortunately, data available to support the preremedial design are often sparse and insufficient for accurately estimating contaminated soil volumes, resulting in significant uncertainty associated with these volume estimates. The uncertainty in the soil volume estimates significantly contributes to the uncertainty in the overall project cost estimates, especially since excavation and off-site disposal are the primary cost items in soil remedial action projects. The Army Corps of Engineers Buffalo District's experience has been that historical contaminated soil volume estimates developed under the Formerly Utilized Sites Remedial Action Program (FUSRAP) often underestimated the actual volume of subsurface contaminated soils requiring excavation during the course of a remedial activity. In response, the Buffalo District has adopted a variety of programmatic methods for addressing contaminated volume uncertainties. These include developing final status survey protocols prior to remedial design, explicitly estimating the uncertainty associated with volume estimates, investing in predesign data collection to reduce volume uncertainties, and incorporating dynamic work strategies and real-time analytics in predesign characterization and remediation activities. This paper describes some of these experiences in greater detail, drawing from the knowledge gained at Ashland1, Ashland2, Linde, and Rattlesnake Creek. In the case of Rattlesnake Creek, these approaches provided the Buffalo District with an accurate predesign contaminated volume estimate and resulted in one of the first successful FUSRAP fixed-price remediation contracts for the Buffalo District.
SLSF loop handling system. Volume I. Structural analysis. [LMFBR
Energy Technology Data Exchange (ETDEWEB)
Ahmed, H.; Cowie, A.; Ma, D.
1978-10-01
SLSF loop handling system was analyzed for deadweight and postulated dynamic loading conditions, identified in Chapters II and III in Volume I of this report, using a linear elastic static equivalent method of stress analysis. Stress analysis of the loop handling machine is presented in Volume I of this report. Chapter VII in Volume I of this report is a contribution by EG and G Co., who performed the work under ANL supervision.
DEFF Research Database (Denmark)
Klausen, Thomas Kjær
- serves a multitude of functions in the mammalian cell, regulating the membrane potential (Em), cell volume, protein activity and the driving force for facilitated transporters giving Cl- and Cl- channels a major potential of regulating cellular function. These functions include control of the cell cycle...... of volume perturbations evolution have developed system of channels and transporters to tightly control volume homeostasis. In the past decades evidence has been mounting, that the importance of these volume regulated channels and transporters are not restricted to the defense of cellular volume......, controlled cell death and cellular migration. Volume regulatory mechanisms has long been in focus for regulating cellular proliferation and my thesis work have been focusing on the role of Cl- channels in proliferation with specific emphasis on ICl, swell. Pharmacological blockage of the ubiquitously...
Magoules, Frederic
2011-01-01
Exploring new variations of classical methods as well as recent approaches appearing in the field, Computational Fluid Dynamics demonstrates the extensive use of numerical techniques and mathematical models in fluid mechanics. It presents various numerical methods, including finite volume, finite difference, finite element, spectral, smoothed particle hydrodynamics (SPH), mixed-element-volume, and free surface flow.Taking a unified point of view, the book first introduces the basis of finite volume, weighted residual, and spectral approaches. The contributors present the SPH method, a novel ap
Precision volume measurement system.
Energy Technology Data Exchange (ETDEWEB)
Fischer, Erin E.; Shugard, Andrew D.
2004-11-01
A new precision volume measurement system based on a Kansas City Plant (KCP) design was built to support the volume measurement needs of the Gas Transfer Systems (GTS) department at Sandia National Labs (SNL) in California. An engineering study was undertaken to verify or refute KCP's claims of 0.5% accuracy. The study assesses the accuracy and precision of the system. The system uses the ideal gas law and precise pressure measurements (of low-pressure helium) in a temperature and computer controlled environment to ratio a known volume to an unknown volume.
Orban, Marek; Bruce, Charles J; Pressman, Gregg S; Leinveber, Pavel; Romero-Corral, Abel; Korinek, Josef; Konecny, Tomas; Villarraga, Hector R; Kara, Tomas; Caples, Sean M; Somers, Virend K
2008-12-01
Using the Mueller maneuver (MM) to simulate obstructive sleep apnea (OSA), our aim was to investigate acute changes in left-sided cardiac morphologic characteristics and function which might develop with apneas occurring during sleep. Strong evidence supports a relation between OSA and both atrial fibrillation and heart failure. However, acute effects of airway obstruction on cardiac structure and function have not been well defined. In addition, it is unclear how OSA might contribute to the development of atrial fibrillation and heart failure. Echocardiography was used in healthy young adults to measure various parameters of cardiac structure and function. Subjects were studied at baseline, during, and immediately after performance of the MM and after a 10-minute recovery. Continuous heart rate, blood pressure, and pulse oximetry measurements were made. During the MM, left atrial (LA) volume index markedly decreased. Left ventricular (LV) end-systolic dimension increased in association with a decrease in LV ejection fraction. On release of the maneuver, there was a compensatory increase in blood flow to the left side of the heart, with stroke volume, ejection fraction, and cardiac output exceeding baseline. After 10 minutes of recovery, all parameters returned to baseline. In conclusion, sudden imposition of severe negative intrathoracic pressure led to an abrupt decrease in LA volume and a decrease in LV systolic performance. These changes reflected an increase in LV afterload. Repeated swings in afterload burden and chamber volumes may have implications for the future development of atrial fibrillation and heart failure.
Nonlinear dynamics new directions models and applications
Ugalde, Edgardo
2015-01-01
This book, along with its companion volume, Nonlinear Dynamics New Directions: Theoretical Aspects, covers topics ranging from fractal analysis to very specific applications of the theory of dynamical systems to biology. This second volume contains mostly new applications of the theory of dynamical systems to both engineering and biology. The first volume is devoted to fundamental aspects and includes a number of important new contributions as well as some review articles that emphasize new development prospects. The topics addressed in the two volumes include a rigorous treatment of fluctuations in dynamical systems, topics in fractal analysis, studies of the transient dynamics in biological networks, synchronization in lasers, and control of chaotic systems, among others. This book also: · Develops applications of nonlinear dynamics on a diversity of topics such as patterns of synchrony in neuronal networks, laser synchronization, control of chaotic systems, and the study of transient dynam...
DEFF Research Database (Denmark)
Advances in Soil Dynamics, Volume 3, represents the culmination of the work undertaken by the Advances in Soil Dynamics Monograph Committee, PM-45-01, about 15 years ago to summarize important developments in this field over the last 35 years. When this project was initiated, the main goal...... was to abridge major strides made in the general area of soil dynamics during the sixties, seventies, and eighties. However, by about the mid-nineties soil dynamics research in the US and much of the developed world had come to a virtual standstill. Although significant progress was made prior to the mid......-nineties, we still do not have a sound fundamental knowledge of soil-machine and soil-plant interactions. It is the hope of the editors that these three volumes will provide a ready reference for much needed future research in this area....
DEFF Research Database (Denmark)
Advances in Soil Dynamics, Volume 3, represents the culmination of the work undertaken by the Advances in Soil Dynamics Monograph Committee, PM-45-01, about 15 years ago to summarize important developments in this field over the last 35 years. When this project was initiated, the main goal...... was to abridge major strides made in the general area of soil dynamics during the sixties, seventies, and eighties. However, by about the mid-nineties soil dynamics research in the US and much of the developed world had come to a virtual standstill. Although significant progress was made prior to the mid......-nineties, we still do not have a sound fundamental knowledge of soil-machine and soil-plant interactions. It is the hope of the editors that these three volumes will provide a ready reference for much needed future research in this area....
Giant Volume Change of Active Gels under Continuous Flow
2014-04-21
communication17 of BZ droplets and chemical self-organiza- tion,18 the properties and potential of self-oscillating gels in a microfluidic system have yet to be...active gels driven by the Belousov−Zhabotinsky reaction. These results demon- strate that microfluidics offers a useful and facile experimental...soft materials and microfluidic systems. ■ INTRODUCTION This paper reports the use of a continuous reactant flow in a microfluidic system to achieve
Energy Technology Data Exchange (ETDEWEB)
Ostebee, Heath Michael; Ziminsky, Willy Steve; Johnson, Thomas Edward; Keener, Christopher Paul
2017-01-17
The present application provides a variable volume combustor for use with a gas turbine engine. The variable volume combustor may include a liner, a number of micro-mixer fuel nozzles positioned within the liner, and a linear actuator so as to maneuver the micro-mixer fuel nozzles axially along the liner.
DEFF Research Database (Denmark)
Klausen, Thomas Kjær
of volume perturbations evolution have developed system of channels and transporters to tightly control volume homeostasis. In the past decades evidence has been mounting, that the importance of these volume regulated channels and transporters are not restricted to the defense of cellular volume...... but are also essential for a number of physiological processes such as proliferation, controlled cell death, migration and endocrinology. The thesis have been focusing on two Channels, namely the swelling activated Cl- channel (ICl, swell) and the transient receptor potential Vanilloid (TRPV4) channel. I: Cl......- serves a multitude of functions in the mammalian cell, regulating the membrane potential (Em), cell volume, protein activity and the driving force for facilitated transporters giving Cl- and Cl- channels a major potential of regulating cellular function. These functions include control of the cell cycle...
Institute of Scientific and Technical Information of China (English)
郝晓光
2013-01-01
Objective To explore the clinical value of 64-slice CT coronary CTA dynamic volume rendering images auxiliary diagnosis of myocardial bridge. Methods 96 patients underwent coronary CTA from January 2009 to the end of December 2012, with confirm of coronary angiography, were chosen. CT images are routinely reconstructed in the best phase period and in 0-90% phase period, an interval of 10%. Reconstruction data was sent to the workstation to get the MPR, the CPR, as well as dynamic volume rendering images. Images were analyzed by the two groups of doctors of medical imaging department to determine whether the presence of myocardial bridge of the left anterior descending artery based on static images, both static and dynamic volume images, respectively. Results 96 cases with myocardial bridge of the left anterior descending artery confirmed by coronary angiography, 83 cases were diagnosed by the static CTA image, 93 cases were diagnosed by both static and dynamic volume images. The sensitivity of two groups was 93.75% and 82.29%, specificity 99.68% and 99.57%, respectively. Conclusion The comprehensive analysis of the 64-slice spiral CT coronary CTA static and dynamic volume rendering images can improve the accuracy of the diagnosis of left anterior descending artery myocardial bridge.% 目的探索64层螺旋CT冠状动脉CTA动态容积再现图像辅助诊断心肌桥的临床应用价值。方法选择我院2009年1月-2012年12月行冠状动脉CTA检查并经冠脉造影证实的心肌桥96例，所有CT图像均进行常规best phase期相重建及0-90%、间隔10%的多期相重建，重建后的数据传送至工作站进行MPR、CPR重建以及动态容积再现处理。图像由两组医师分别根据静态图像、静态加动态容积再现图像判断是否存在前降支心肌桥，诊断结果分别统计，并进行统计学分析。结果经冠脉造影证实的前降支心肌桥患者96例中，静态CTA图像诊断肌桥83例，静
IVUS coronary volume alignment for distinct phases
Matsumoto, Monica Mitiko Soares; Lemos, Pedro Alves; Furuie, Sergio Shiguemi
2009-02-01
Image-based intravascular ultrasound (IVUS) cardiac phase detection allows coronary volume reconstruction in different phases. Consecutive volumes are not necessarily spatially aligned due to longitudinal movement of the catheter. Besides ordinary pullback velocity, there is a relative longitudinal movement of the heart vessel walls and the transducer, due to myocardial contraction. In this manuscript, we aim to spatially align cardiac phase coronary IVUS volumes. In addition, we want to investigate this non-linear longitudinal catheter movement. With this purpose, we have analyzed 120 simulated IVUS images and 10 real IVUS pullbacks. We implemented the following methodology. Firstly, we built IVUS volume for each distinct phase. Secondly, each IVUS volume was transformed into a parametric signal of average frame intensity. We have used these signals to make correlation in space with a reference one. Then we estimated the spatial distance between the distinct IVUS volumes and the reference. We have tested in simulated images and real examinations. We have also observed similar pattern in real IVUS examinations. This spatial alignment method is feasible and useful as a step towards dynamic studies of IVUS examination.
Vos, Jaap Jan; Poterman, Marieke; Struys, Michel; Scheeren, Thomas; Kalmar, A.F.
2013-01-01
Background and Goal of Study: Dynamic preload variables derived from the arterial pressure waveform have been shown to accurately predict fluid responsiveness in mechanically ventilated patients. One of these variables, stroke volume variation (SVV), can also be obtained noninvasively by the finger
Volume regulation in epithelia
DEFF Research Database (Denmark)
Larsen, Erik Hviid; Hoffmann, Else Kay
2016-01-01
function of iso-osmotic fluid transport that depends on Na+ recirculation. The causative relationship is discussed for a fluid-absorbing and a fluid-secreting epithelium of which the Na+ recirculation mechanisms have been identified. A large number of transporters and ion channels involved in cell volume...... regulation are cloned. The volume-regulated anion channel (VRAC) exhibiting specific electrophysiological characteristics seems exclusive to serve cell volume regulation. This is contrary to K+ channels as well as cotransporters and exchange mechanisms that may serve both transepithelial transport and cell...
Towards the Amplituhedron Volume
Ferro, Livia; Orta, Andrea; Parisi, Matteo
2015-01-01
It has been recently conjectured that scattering amplitudes in planar N=4 super Yang-Mills are given by the volume of the (dual) amplituhedron. In this paper we show some interesting connections between the tree-level amplituhedron and a special class of differential equations. In particular we demonstrate how the amplituhedron volume for NMHV amplitudes is determined by these differential equations. The new formulation allows for a straightforward geometric description, without any reference to triangulations. Finally we discuss possible implications for volumes related to generic N^kMHV amplitudes.
Energy Technology Data Exchange (ETDEWEB)
Becker, B.G.; Lane, D.A.; Max, N.L.
1995-03-01
Flow volumes are extended for use in unsteady (time-dependent) flows. The resulting unsteady flow volumes are the 3 dimensional analog of streamlines. There are few examples where methods other than particle tracing have been used to visualize time varying flows. Since particle paths can become convoluted in time there are additional considerations to be made when extending any visualization technique to unsteady flows. We will present some solutions to the problems which occur in subdivision, rendering, and system design. We will apply the unsteady flow volumes to a variety of field types including moving multi-zoned curvilinear grids.
Rathakrishnan, Ethirajan
2014-01-01
This is an introductory level textbook which explains the elements of high temperature and high-speed gas dynamics. written in a clear and easy to follow style, the author covers all the latest developments in the field including basic thermodynamic principles, compressible flow regimes and waves propagation in one volume covers theoretical modeling of High Enthalpy Flows, with particular focus on problems in internal and external gas-dynamic flows, of interest in the fields of rockets propulsion and hypersonic aerodynamics High enthalpy gas dynamics is a compulsory course for aerospace engine
Fiszdon, W
1965-01-01
Fluid Dynamics Transactions, Volume 2 compiles 46 papers on fluid dynamics, a subdiscipline of fluid mechanics that deals with fluid flow. The topics discussed in this book include developments in interference theory for aeronautical applications; diffusion from sources in a turbulent boundary layer; unsteady motion of a finite wing span in a compressible medium; and wall pressure covariance and comparison with experiment. The certain classes of non-stationary axially symmetric flows in magneto-gas-dynamics; description of the phenomenon of secondary flows in curved channels by means of co
Landman, Bruce
2014-01-01
""Integers"" is a refereed online journal devoted to research in the area of combinatorial number theory. It publishes original research articles in combinatorics and number theory. This work presents all papers of the 2013 volume in book form.
Renormalized Volumes with Boundary
Gover, A Rod
2016-01-01
We develop a general regulated volume expansion for the volume of a manifold with boundary whose measure is suitably singular along a separating hypersurface. The expansion is shown to have a regulator independent anomaly term and a renormalized volume term given by the primitive of an associated anomaly operator. These results apply to a wide range of structures. We detail applications in the setting of measures derived from a conformally singular metric. In particular, we show that the anomaly generates invariant (Q-curvature, transgression)-type pairs for hypersurfaces with boundary. For the special case of anomalies coming from the volume enclosed by a minimal hypersurface ending on the boundary of a Poincare--Einstein structure, this result recovers Branson's Q-curvature and corresponding transgression. When the singular metric solves a boundary version of the constant scalar curvature Yamabe problem, the anomaly gives generalized Willmore energy functionals for hypersurfaces with boundary. Our approach ...
Environmental chemistry: Volume A
Energy Technology Data Exchange (ETDEWEB)
Yen, T.F.
1999-08-01
This is an extensive introduction to environmental chemistry for engineering and chemical professionals. The contents of Volume A include a brief review of basic chemistry prior to coverage of litho, atmo, hydro, pedo, and biospheres.
DEFF Research Database (Denmark)
Darkner, Sune; Sporring, Jon
2011-01-01
Mutual Information (MI) and normalized mutual information (NMI) are popular choices as similarity measure for multimodal image registration. Presently, one of two approaches is often used for estimating these measures: The Parzen Window (PW) and the Generalized Partial Volume (GPV). Their theoret......Mutual Information (MI) and normalized mutual information (NMI) are popular choices as similarity measure for multimodal image registration. Presently, one of two approaches is often used for estimating these measures: The Parzen Window (PW) and the Generalized Partial Volume (GPV...
Dynamic gamma knife radiosurgery.
Luan, Shuang; Swanson, Nathan; Chen, Zhe; Ma, Lijun
2009-03-21
Gamma knife has been the treatment of choice for various brain tumors and functional disorders. Current gamma knife radiosurgery is planned in a 'ball-packing' approach and delivered in a 'step-and-shoot' manner, i.e. it aims to 'pack' the different sized spherical high-dose volumes (called 'shots') into a tumor volume. We have developed a dynamic scheme for gamma knife radiosurgery based on the concept of 'dose-painting' to take advantage of the new robotic patient positioning system on the latest Gamma Knife C and Perfexion units. In our scheme, the spherical high dose volume created by the gamma knife unit will be viewed as a 3D spherical 'paintbrush', and treatment planning reduces to finding the best route of this 'paintbrush' to 'paint' a 3D tumor volume. Under our dose-painting concept, gamma knife radiosurgery becomes dynamic, where the patient moves continuously under the robotic positioning system. We have implemented a fully automatic dynamic gamma knife radiosurgery treatment planning system, where the inverse planning problem is solved as a traveling salesman problem combined with constrained least-square optimizations. We have also carried out experimental studies of dynamic gamma knife radiosurgery and showed the following. (1) Dynamic gamma knife radiosurgery is ideally suited for fully automatic inverse planning, where high quality radiosurgery plans can be obtained in minutes of computation. (2) Dynamic radiosurgery plans are more conformal than step-and-shoot plans and can maintain a steep dose gradient (around 13% per mm) between the target tumor volume and the surrounding critical structures. (3) It is possible to prescribe multiple isodose lines with dynamic gamma knife radiosurgery, so that the treatment can cover the periphery of the target volume while escalating the dose for high tumor burden regions. (4) With dynamic gamma knife radiosurgery, one can obtain a family of plans representing a tradeoff between the delivery time and the dose
Dynamic gamma knife radiosurgery
Luan, Shuang; Swanson, Nathan; Chen, Zhe; Ma, Lijun
2009-03-01
Gamma knife has been the treatment of choice for various brain tumors and functional disorders. Current gamma knife radiosurgery is planned in a 'ball-packing' approach and delivered in a 'step-and-shoot' manner, i.e. it aims to 'pack' the different sized spherical high-dose volumes (called 'shots') into a tumor volume. We have developed a dynamic scheme for gamma knife radiosurgery based on the concept of 'dose-painting' to take advantage of the new robotic patient positioning system on the latest Gamma Knife C™ and Perfexion™ units. In our scheme, the spherical high dose volume created by the gamma knife unit will be viewed as a 3D spherical 'paintbrush', and treatment planning reduces to finding the best route of this 'paintbrush' to 'paint' a 3D tumor volume. Under our dose-painting concept, gamma knife radiosurgery becomes dynamic, where the patient moves continuously under the robotic positioning system. We have implemented a fully automatic dynamic gamma knife radiosurgery treatment planning system, where the inverse planning problem is solved as a traveling salesman problem combined with constrained least-square optimizations. We have also carried out experimental studies of dynamic gamma knife radiosurgery and showed the following. (1) Dynamic gamma knife radiosurgery is ideally suited for fully automatic inverse planning, where high quality radiosurgery plans can be obtained in minutes of computation. (2) Dynamic radiosurgery plans are more conformal than step-and-shoot plans and can maintain a steep dose gradient (around 13% per mm) between the target tumor volume and the surrounding critical structures. (3) It is possible to prescribe multiple isodose lines with dynamic gamma knife radiosurgery, so that the treatment can cover the periphery of the target volume while escalating the dose for high tumor burden regions. (4) With dynamic gamma knife radiosurgery, one can obtain a family of plans representing a tradeoff between the delivery time and the
Dynamic gamma knife radiosurgery
Energy Technology Data Exchange (ETDEWEB)
Luan Shuang; Swanson, Nathan; Chen Zhe [Department of Computer Science, University of New Mexico, Albuquerque, NM 87131 (United States); Ma Lijun [Department of Radiation Oncology, University of California San Francisco, San Francisco, CA 94143 (United States)], E-mail: sluan@cs.unm.edu, E-mail: nate@cs.unm.edu, E-mail: zchen@cs.unm.edu, E-mail: lijunma@radonc.ucsf.edu
2009-03-21
Gamma knife has been the treatment of choice for various brain tumors and functional disorders. Current gamma knife radiosurgery is planned in a 'ball-packing' approach and delivered in a 'step-and-shoot' manner, i.e. it aims to 'pack' the different sized spherical high-dose volumes (called 'shots') into a tumor volume. We have developed a dynamic scheme for gamma knife radiosurgery based on the concept of 'dose-painting' to take advantage of the new robotic patient positioning system on the latest Gamma Knife C(TM) and Perfexion(TM) units. In our scheme, the spherical high dose volume created by the gamma knife unit will be viewed as a 3D spherical 'paintbrush', and treatment planning reduces to finding the best route of this 'paintbrush' to 'paint' a 3D tumor volume. Under our dose-painting concept, gamma knife radiosurgery becomes dynamic, where the patient moves continuously under the robotic positioning system. We have implemented a fully automatic dynamic gamma knife radiosurgery treatment planning system, where the inverse planning problem is solved as a traveling salesman problem combined with constrained least-square optimizations. We have also carried out experimental studies of dynamic gamma knife radiosurgery and showed the following. (1) Dynamic gamma knife radiosurgery is ideally suited for fully automatic inverse planning, where high quality radiosurgery plans can be obtained in minutes of computation. (2) Dynamic radiosurgery plans are more conformal than step-and-shoot plans and can maintain a steep dose gradient (around 13% per mm) between the target tumor volume and the surrounding critical structures. (3) It is possible to prescribe multiple isodose lines with dynamic gamma knife radiosurgery, so that the treatment can cover the periphery of the target volume while escalating the dose for high tumor burden regions. (4) With dynamic gamma knife radiosurgery, one can
McMahon, Troy
2015-05-01
© 2015 IEEE. Reachable volumes are a new technique that allows one to efficiently restrict sampling to feasible/reachable regions of the planning space even for high degree of freedom and highly constrained problems. However, they have so far only been applied to graph-based sampling-based planners. In this paper we develop the methodology to apply reachable volumes to tree-based planners such as Rapidly-Exploring Random Trees (RRTs). In particular, we propose a reachable volume RRT called RVRRT that can solve high degree of freedom problems and problems with constraints. To do so, we develop a reachable volume stepping function, a reachable volume expand function, and a distance metric based on these operations. We also present a reachable volume local planner to ensure that local paths satisfy constraints for methods such as PRMs. We show experimentally that RVRRTs can solve constrained problems with as many as 64 degrees of freedom and unconstrained problems with as many as 134 degrees of freedom. RVRRTs can solve problems more efficiently than existing methods, requiring fewer nodes and collision detection calls. We also show that it is capable of solving difficult problems that existing methods cannot.
Development of a theoretical framework for analyzing cerebrospinal fluid dynamics
DEFF Research Database (Denmark)
Cohen, Benjamin; Voorhees, Abram; Vedel, Søren
2009-01-01
Background: To date hydrocephalus researchers acknowledge the need for rigorous but utilitarian fluid mechanics understanding and methodologies in studying normal and hydrocephalic intracranial dynamics. Pressure volume models and electric circuit analogs introduced pressure into volume conservat......Background: To date hydrocephalus researchers acknowledge the need for rigorous but utilitarian fluid mechanics understanding and methodologies in studying normal and hydrocephalic intracranial dynamics. Pressure volume models and electric circuit analogs introduced pressure into volume...
Kaiser, James; Rollins, Clint
2011-01-01
Agol has conjectured that minimally twisted n-chain links are the smallest volume hyperbolic manifolds with n cusps, for n at most 10. In his thesis, Venzke mentions that these cannot be smallest volume for n at least 11, but does not provide a proof. In this paper, we give a proof of Venzke's statement. The proof for n at least 60 is completely rigorous. The proof for n between 11 and 59 uses a computer calculation, and can be made rigorous for manifolds of small enough complexity, using methods of Moser and Milley. Finally, we prove that the n-chain link with 2m or 2m+1 half-twists cannot be the minimal volume hyperbolic manifold with n cusps, provided n is at least 60 or |m| is at least 8, and we give computational data indicating this remains true for smaller n and |m|.
Directory of Open Access Journals (Sweden)
Bogdan DINU
2014-04-01
Full Text Available Big Data can revolutionize humanity. Hidden within the huge amounts and variety of the data we are creating we may find information, facts, social insights and benchmarks that were once virtually impossible to find or were simply inexistent. Large volumes of data allow organizations to tap in real time the full potential of all the internal or external information they possess. Big data calls for quick decisions and innovative ways to assist customers and the society as a whole. Big data platforms and product portfolio will help customers harness to the full the value of big data volumes. This paper deals with technical and technological issues related to handling big data volumes in the Big Data environment.
Wlodarczyk, Przemyslaw; Zachorowski, Jerzy; Lipinski, Marcin
2012-01-01
We investigate one of the most sensitive devices for measuring magnetic fields, the, so-called, AMOR magnetometer. The device exploits a specific nonlinear optical phenomenon (amplitude-modulated nonlinear magneto-optical rotation) for ultra-precise magnetic field detection. It allows measuring the field with a sensitivity of 10^-14 T/Hz^-1/2 within a dynamic range of 10-4 T. Such high sensitivity and the dynamic range covering the Earth magnetic field are desired in context of many practical application of the device. By elaborating the electronic model of the magnetometer we study its different characteristics in various arrangements. It allows us to optimize the device regarding different requirements, e.g., technical simplicity, data processing, etc. It is shown that the device may be automated operating it in the self-oscillation mode. Particularly, we show that the magnetometer instantly responses to the magnetic field change. Our numerical analyses are confirmed with experimental results obtained in on...
Directory of Open Access Journals (Sweden)
Barreira N
2005-01-01
Full Text Available The topological active volumes (TAVs model is a general model for 3D image segmentation. It is based on deformable models and integrates features of region-based and boundary-based segmentation techniques. Besides segmentation, it can also be used for surface reconstruction and topological analysis of the inside of detected objects. The TAV structure is flexible and allows topological changes in order to improve the adjustment to object's local characteristics, find several objects in the scene, and identify and delimit holes in detected structures. This paper describes the main features of the TAV model and shows its ability to segment volumes in an automated manner.
Gerke, Tim D.
Presented in this thesis is an investigation into aperiodic volume optical devices. The three main topics of research and discussion are the aperiodic volume optical devices that we call computer-generated volume holograms (CGVH), defects within periodic 3D photonic crystals, and non-periodic, but ordered 3D quasicrystals. The first of these devices, CGVHs, are designed and investigated numerically and experimentally. We study the performance of multi-layered amplitude computer-generated volume holograms in terms of efficiency and angular/frequency selectivity. Simulation results show that such aperiodic devices can increase diffraction efficiency relative to periodic amplitude volume holograms while maintaining angular and wavelength selectivity. CGVHs are also designed as voxelated volumes using a new projection optimization algorithm. They are investigated using a volumetric diffraction simulation and a standard 3D beam propagation technique as well as experimentally. Both simulation and experiment verify that the structures function according to their design. These represent the first diffractive structures that have the capacity for generating arbitrary transmission and reflection wave fronts and that provide the ability for multiplexing arbitrary functionality given different illumination conditions. Also investigated and discussed in this thesis are 3D photonic crystals and quasicrystals. We demonstrate that these devices can be fabricated using a femtosecond laser direct writing system that is particularly appropriate for fabrication of such arbitrary 3D structures. We also show that these devices can provide 3D partial bandgaps which could become complete bandgaps if fabricated using high index materials or by coating lower index materials with high index metals. Our fabrication method is particularly suited to the fabrication of engineered defects within the periodic or quasi-periodic systems. We demonstrate the potential for fabricating defects within
Energy Technology Data Exchange (ETDEWEB)
Adam, C., E-mail: adam@fpaxp1.usc.es [Departamento de Física de Partículas, Universidad de Santiago de Compostela and Instituto Galego de Física de Altas Enerxias (IGFAE), E-15782 Santiago de Compostela (Spain); Haberichter, M. [School of Mathematics, Statistics and Actuarial Science, University of Kent, Canterbury, CT2 7NF (United Kingdom); Wereszczynski, A. [Institute of Physics, Jagiellonian University, Lojasiewicza 11, Kraków (Poland)
2016-03-10
There exists, in general, no unique definition of the size (volume, area, etc., depending on dimension) of a soliton. Here we demonstrate that the geometric volume (area etc.) of a soliton is singled out in the sense that it exactly coincides with the thermodynamical or continuum-mechanical volume. In addition, this volume may be defined uniquely for rather arbitrary solitons in arbitrary dimensions.
Wever, R.; Boks, C.; Stevels, A.
2007-01-01
Traditionally packaging design-for-sustainability (DfS) strongly focuses on resource conservation and material recycling. The type and amount of materials used has been the driver in design. For consumer electronics (CE) products this weight-based approach is too limited; a volume-based approach is
Emihovich, Catherine; Schroder, Barbara; Panofsky, Carolyn P.
1999-01-01
Introduces a volume that examines the issue of critical thinking and whether or not it is culturally specific, discussing recent research on the subject. The papers focus on critical thinking and culture, historical consciousness and critical thinking, critical thinking as cultural-historical practice, culture and the development of critical…
Volume change theory for syringomyelia: A new perspective.
Rai, Survendra Kumar Rajdeo; Rai, Pooja Survendra Kumar
2015-01-01
The etiopathogenesis of syringomyelia is still an enigma. The authors present a novel theory based on fluid dynamics at the craniovertebral (CV) junction to explain the genesis of syringomyelia (SM). The changes in volume of spinal canal, spinal cord, central canal and spinal subarachnoid space (SSS) in relation to the posterior fossa have been analysed, specifically during postural movements of flexion and extension. The effect of fluctuations in volume of spinal canal and its contents associated with cerebrospinal fluid (CSF) flow dynamics at the CV junction have been postulated to cause the origin and propagation of the syringomyelia. The relevant literature on the subject has been reviewed and the author's theory has been discussed. Volume of spinal canal in flexion is always greater than that in extension. Flexion of spine causes narrowing of the ventral subarachnoid space (SAS) and widening of dorsal SAS while extension causes reverse changes leading to fluid movement in dorsal spinal SAS in flexion and ventral spinal SAS in extension. Cervical and lumbar spinal region with maximum bulk hence maximum area and volume undergo maximum deformation during postural changes. SSS CSF is the difference between the volume of spinal canal and spinal cord, varies in flexion and extension which is compensated by changes in posterior fossa (CSF) volume in normal circumstances. Blocked SAS at foramen magnum donot permit spinal SAS CSF exchange which during postural changes is compensated by cavitatory/cystic (syrinx) change at locations in cervical and lumbar spine with propensity for maximum deformation. Augmentation of posterior fossa volume by decompression helps by normalization of this CSF exchange dynamics but immobilizing the spinal movement theoretically will cease any dynamic volume changes thereby minimizing the destructive influence of the fluid exchange on the cord. Thus, this theory strengthens the rational of treating patients by either methodology.
Directory of Open Access Journals (Sweden)
Jo-An Atkinson
2017-02-01
Full Text Available Development of effective policy responses to address complex public health problems can be challenged by a lack of clarity about the interaction of risk factors driving the problem, differing views of stakeholders on the most appropriate and effective intervention approaches, a lack of evidence to support commonly implemented and acceptable intervention approaches, and a lack of acceptance of effective interventions. Consequently, political considerations, community advocacy and industry lobbying can contribute to a hotly contested debate about the most appropriate course of action; this can hinder consensus and give rise to policy resistance. The problem of alcohol misuse and its associated harms in New South Wales (NSW, Australia, provides a relevant example of such challenges. Dynamic simulation modelling is increasingly being valued by the health sector as a robust tool to support decision making to address complex problems. It allows policy makers to ask ‘what-if’ questions and test the potential impacts of different policy scenarios over time, before solutions are implemented in the real world. Participatory approaches to modelling enable researchers, policy makers, program planners, practitioners and consumer representatives to collaborate with expert modellers to ensure that models are transparent, incorporate diverse evidence and perspectives, are better aligned to the decision-support needs of policy makers, and can facilitate consensus building for action. This paper outlines a procedure for embedding stakeholder engagement and consensus building in the development of dynamic simulation models that can guide the development of effective, coordinated and acceptable policy responses to complex public health problems, such as alcohol-related harms in NSW.
Institute of Scientific and Technical Information of China (English)
党一纵; 王鲁; 范群波
2012-01-01
Atomic structure evolution and diffusivity during the cooling of Zr5oCu50 metallic liquid are studied by molecular dynamics (MD) simulation. Based on the theory that free volume is equal to the volume difference between the amorphous materials and their crystalline counterpart, a new method of annihilating rate of free volume has been developed and applied to predict the critical microscopic glass transition temperature. The predicted critical temperature Tc was 969. 5 K, which is close to the MCT(mode-coupling theory) value of 978. 4 K, and the caloric glass transition temperature Tg was 731 K, which is also close to the value of 725 K determined from the curve of average atomic volume with temperature. Without calculation of diffusion coefficients at a serial of specified temperatures, the developed method is more convenient than former methods to calculate Tc and Tg.%利用分子动力学模拟了Zr50Cu50金属玻璃的形成过程,并获得了不同温度下合金的原子构型.借助金属玻璃中自由体积量等于金属玻璃与对应晶体的体积差理论提出一种自由体积湮没速度法,对Zr50Cu50金属玻璃形成过程中的临界玻璃态转变温度Tc以及热力学玻璃态转变温度Tg进行预测.用该方法确定出的Tc(969.5 K)与利用模式耦合理论计算获得的Tc (978.4 K)接近；Tg(731 K)与利用平均原子体积随温度变化关系曲线确定的Tg(725 K)相近.运用自由体积湮没速度法计算的Tc和Tg无需计算各温度下的原子扩散系数,节省了计算时间.
Cell Volume Regulation and Apoptotic Volume Decrease in Rat Distal Colon Superficial Enterocytes
Directory of Open Access Journals (Sweden)
Stefania Antico
2013-12-01
Full Text Available Background: The colon epithelium is physiologically exposed to osmotic stress, and the activation of cell volume regulation mechanisms is essential in colonocyte physiology. Moreover, colon is characterized by a high apoptotic rate of mature cells balancing the high division rate of stem cells. Aim: The aim of the present work was to investigate the main cell volume regulation mechanisms in rat colon surface colonocytes and their role in apoptosis. Methods: Cell volume changes were measured by light microscopy and video imaging on colon explants; apoptosis sign appearance was monitored by confocal microscopy on annexin V/propidium iodide labeled explants. Results: Superficial colonocytes showed a dynamic regulation of their cell volume during anisosmotic conditions with a Regulatory Volume Increase (RVI response following hypertonic shrinkage and Regulatory Volume Decrease (RVD response following hypotonic swelling. RVI was completely inhibited by bumetanide, while RVD was completely abolished by high K+ or iberiotoxin treatment and by extracellular Ca2+ removal. DIDS incubation was also able to affect the RVD response. When colon explants were exposed to H2O2 as apoptotic inducer, colonocytes underwent an isotonic volume decrease ascribable to Apoptotic Volume Decrease (AVD within about four hours of exposure. AVD was shown to precede annexin V positivity. It was also inhibited by high K+ or iberiotoxin treatment. Interestingly, treatment with iberiotoxin significantly inhibited apoptosis progression. Conclusions: In rat superficial colonocytes K+ efflux through high conductance Ca2+-activated K+ channels (BK channels was demonstrated to be the main mechanism of RVD and to plays also a crucial role in the AVD process and in the progression of apoptosis.
Flat-panel volume CT: fundamental principles, technology, and applications.
Gupta, Rajiv; Cheung, Arnold C; Bartling, Soenke H; Lisauskas, Jennifer; Grasruck, Michael; Leidecker, Christianne; Schmidt, Bernhard; Flohr, Thomas; Brady, Thomas J
2008-01-01
Flat-panel volume computed tomography (CT) systems have an innovative design that allows coverage of a large volume per rotation, fluoroscopic and dynamic imaging, and high spatial resolution that permits visualization of complex human anatomy such as fine temporal bone structures and trabecular bone architecture. In simple terms, flat-panel volume CT scanners can be thought of as conventional multidetector CT scanners in which the detector rows have been replaced by an area detector. The flat-panel detector has wide z-axis coverage that enables imaging of entire organs in one axial acquisition. Its fluoroscopic and angiographic capabilities are useful for intraoperative and vascular applications. Furthermore, the high-volume coverage and continuous rotation of the detector may enable depiction of dynamic processes such as coronary blood flow and whole-brain perfusion. Other applications in which flat-panel volume CT may play a role include small-animal imaging, nondestructive testing in animal survival surgeries, and tissue-engineering experiments. Such versatility has led some to predict that flat-panel volume CT will gain importance in interventional and intraoperative applications, especially in specialties such as cardiac imaging, interventional neuroradiology, orthopedics, and otolaryngology. However, the contrast resolution of flat-panel volume CT is slightly inferior to that of multidetector CT, a higher radiation dose is needed to achieve a comparable signal-to-noise ratio, and a slower scintillator results in a longer scanning time.
Miller, Wayne L
2016-08-01
Volume regulation, assessment, and management remain basic issues in patients with heart failure. The discussion presented here is directed at opening a reassessment of the pathophysiology of congestion in congestive heart failure and the methods by which we determine volume overload status. Peer-reviewed historical and contemporary literatures are reviewed. Volume overload and fluid congestion remain primary issues for patients with chronic heart failure. The pathophysiology is complex, and the simple concept of intravascular fluid accumulation is not adequate. The dynamics of interstitial and intravascular fluid compartment interactions and fluid redistribution from venous splanchnic beds to central pulmonary circulation need to be taken into account in strategies of volume management. Clinical bedside evaluations and right heart hemodynamic assessments can alert clinicians of changes in volume status, but only the quantitative measurement of total blood volume can help identify the heterogeneity in plasma volume and red blood cell mass that are features of volume overload in patients with chronic heart failure and help guide individualized, appropriate therapy-not all volume overload is the same. © 2016 American Heart Association, Inc.
DEFF Research Database (Denmark)
Frost, H; Mortensen, C.R.; Secher, Niels H.
2017-01-01
In healthy humans, stroke volume (SV) and cardiac output (CO) do not increase with expansion of the central blood volume by head-down tilt or administration of fluid. Here, we exposed 85 patients to Trendelenburg's position about one hour after surgery while cardiovascular variables were determined...... non-invasively by Modelflow. In Trendelenburg's position, SV (83 ± 19 versus 89 ± 20 ml) and CO (6·2 ± 1·8 versus 6·8 ± 1·8 l/min; both Pheart rate (75 ± 15 versus 76 ± 14 b min(-1) ) and mean arterial pressure were unaffected (84 ± 15 versus 84 ± 16 mmHg). For the 33 patients......, determination of SV and/or CO in Trendelenburg's position can be used to evaluate whether a patient is in need of IV fluid as here exemplified after surgery....
2011-08-01
non- uniform rational B-splines (NURBS), 127 and BRL-CAD TM format. This dual-package development allowed for rapid development of components ...next generation of scientists and engineers. A fundamental component of our outreach program is to provide students research experiences at ARL...summer intern. There, I ran Volume Based Morphometry , an application of Statistical Parametric Mapping that was new to the Hirsch lab. I
Muffly, Matthew K; Chen, Michael I; Claure, Rebecca E; Drover, David R; Efron, Bradley; Fitch, William L; Hammer, Gregory B
2017-10-01
In the perioperative period, anesthesiologists and postanesthesia care unit (PACU) nurses routinely prepare and administer small-volume IV injections, yet the accuracy of delivered medication volumes in this setting has not been described. In this ex vivo study, we sought to characterize the degree to which small-volume injections (≤0.5 mL) deviated from the intended injection volumes among a group of pediatric anesthesiologists and pediatric postanesthesia care unit (PACU) nurses. We hypothesized that as the intended injection volumes decreased, the deviation from those intended injection volumes would increase. Ten attending pediatric anesthesiologists and 10 pediatric PACU nurses each performed a series of 10 injections into a simulated patient IV setup. Practitioners used separate 1-mL tuberculin syringes with removable 18-gauge needles (Becton-Dickinson & Company, Franklin Lakes, NJ) to aspirate 5 different volumes (0.025, 0.05, 0.1, 0.25, and 0.5 mL) of 0.25 mM Lucifer Yellow (LY) fluorescent dye constituted in saline (Sigma Aldrich, St. Louis, MO) from a rubber-stoppered vial. Each participant then injected the specified volume of LY fluorescent dye via a 3-way stopcock into IV tubing with free-flowing 0.9% sodium chloride (10 mL/min). The injected volume of LY fluorescent dye and 0.9% sodium chloride then drained into a collection vial for laboratory analysis. Microplate fluorescence wavelength detection (Infinite M1000; Tecan, Mannedorf, Switzerland) was used to measure the fluorescence of the collected fluid. Administered injection volumes were calculated based on the fluorescence of the collected fluid using a calibration curve of known LY volumes and associated fluorescence.To determine whether deviation of the administered volumes from the intended injection volumes increased at lower injection volumes, we compared the proportional injection volume error (loge [administered volume/intended volume]) for each of the 5 injection volumes using a linear
Palazzi, Elisa; Fraedrich, Klaus
2016-01-01
This volume provides an overview of the fluid aspects of the climate system, focusing on basic aspects as well as recent research developments. It will bring together contributions from diverse fields of the physical, mathematical and engineering sciences. The volume will be useful to doctorate students, postdocs and researchers working on different aspects of atmospheric, oceanic and environmental fluid dynamics. It will also be of interest to researchers interested in quantitatively understanding how fluid dynamics can be applied to the climate system, and to climate scientists willing to gain a deeper insight into the fluid mechanics underlying climate processes.
Microscopic origin of volume modulus inflation
Energy Technology Data Exchange (ETDEWEB)
Cicoli, Michele [ICTP, Strada Costiera 11, Trieste 34014 (Italy); Dipartimento di Fisica e Astronomia, Università di Bologna, via Irnerio 46, 40126 Bologna (Italy); INFN, Sezione di Bologna, via Irnerio 46, 40126 Bologna (Italy); Muia, Francesco [Dipartimento di Fisica e Astronomia, Università di Bologna, via Irnerio 46, 40126 Bologna (Italy); INFN, Sezione di Bologna, via Irnerio 46, 40126 Bologna (Italy); Pedro, Francisco Gil [Departamento de Fisica Teórica UAM and Instituto de Fisica Teórica UAM/CSIC, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid (Spain)
2015-12-21
High-scale string inflationary models are in well-known tension with low-energy supersymmetry. A promising solution involves models where the inflaton is the volume of the extra dimensions so that the gravitino mass relaxes from large values during inflation to smaller values today. We describe a possible microscopic origin of the scalar potential of volume modulus inflation by exploiting non-perturbative effects, string loop and higher derivative perturbative corrections to the supergravity effective action together with contributions from anti-branes and charged hidden matter fields. We also analyse the relation between the size of the flux superpotential and the position of the late-time minimum and the inflection point around which inflation takes place. We perform a detailed study of the inflationary dynamics for a single modulus and a two moduli case where we also analyse the sensitivity of the cosmological observables on the choice of initial conditions.
Microscopic Origin of Volume Modulus Inflation
Cicoli, Michele; Pedro, Francisco Gil
2015-01-01
High-scale string inflationary models are in well-known tension with low-energy supersymmetry. A promising solution involves models where the inflaton is the volume of the extra dimensions so that the gravitino mass relaxes from large values during inflation to smaller values today. We describe a possible microscopic origin of the scalar potential of volume modulus inflation by exploiting non-perturbative effects, string loop and higher derivative perturbative corrections to the supergravity effective action together with contributions from anti-branes and charged hidden matter fields. We also analyse the relation between the size of the flux superpotential and the position of the late-time minimum and the inflection point around which inflation takes place. We perform a detailed study of the inflationary dynamics for a single modulus and a two moduli case where we also analyse the sensitivity of the cosmological observables on the choice of initial conditions.
ORGANIZATIONS AND STRATEGIES IN ASTRONOMY VOLUME 7
HECK, ANDRÉ
2006-01-01
This book is the seventh volume under the title Organizations and Strategies in Astronomy (OSA). The OSA series covers a large range of fields and themes: in practice, one could say that all aspects of astronomy-related life and environment are considered in the spirit of sharing specific expertise and lessons learned. The chapters of this book are dealing with socio-dynamical aspects of the astronomy (and related space sciences) community: characteristics of organizations, strategies for development, operational techniques, observing practicalities, journal and magazine profiles, public outreach, publication studies, relationships with the media, research communication, series of conferences, evaluation and selection procedures, research indicators, national specificities, contemporary history, and so on. The experts contributing to this volume have done their best to write in a way understandable to readers not necessarily hyperspecialized in astronomy while providing specific detailed information and somet...
Organizations and Strategies in Astronomy Volume 6
Heck, André
2006-01-01
This book is the sixth volume under the title Organizations and Strategies in Astronomy (OSA). The OSA series is intended to cover a large range of fields and themes. In practice, one could say that all aspects of astronomy-related life and environment are considered in the spirit of sharing specific expertise and lessons learned. The chapters of this book are dealing with socio-dynamical aspects of the astronomy (and related space sciences) community: characteristics of organizations, strategies for development, legal issues, operational techniques, observing practicalities, educational policies, journal and magazine profiles, public outreach, publication studies, relationships with the media, research communication, evaluation and selection procedures, research indicators, national specificities, contemporary history, and so on. The experts contributing to this volume have done their best to write in a way understandable to readers not necessarily hyperspecialized in astronomy while providing specific detai...
Topology optimization using the finite volume method
DEFF Research Database (Denmark)
Computational procedures for topology optimization of continuum problems using a material distribution method are typically based on the application of the finite element method (FEM) (see, e.g. [1]). In the present work we study a computational framework based on the finite volume method (FVM, see...... the well known Reuss lower bound. [1] Bendsøe, M.P.; Sigmund, O. 2004: Topology Optimization - Theory, Methods, and Applications. Berlin Heidelberg: Springer Verlag [2] Versteeg, H. K.; W. Malalasekera 1995: An introduction to Computational Fluid Dynamics: the Finite Volume Method. London: Longman......, e.g. [2]) in order to develop methods for topology design for applications where conservation laws are critical such that element--wise conservation in the discretized models has a high priority. This encompasses problems involving for example mass and heat transport. The work described...
Extinction-Optimized Volume Illumination.
Ament, Marco; Zirr, Tobias; Dachsbacher, Carsten
2016-05-16
We present a novel method to optimize the attenuation of light for the single scattering model in direct volume rendering. A common problem of single scattering is the high dynamic range between lit and shadowed regions due to the exponential attenuation of light along a ray. Moreover, light is often attenuated too strong between a sample point and the camera, hampering the visibility of important features. Our algorithm employs an importance function to selectively illuminate important structures and make them visible from the camera. With the importance function, more light can be transmitted to the features of interest, while contextual structures cast shadows which provide visual cues for perception of depth. At the same time, more scattered light is transmitted from the sample point to the camera to improve the primary visibility of important features. We formulate a minimization problem that automatically determines the extinction along a view or shadow ray to obtain a good balance between sufficient transmittance and attenuation. In contrast to previous approaches, we do not require a computationally expensive solution of a global optimization, but instead provide a closed-form solution for each sampled extinction value along a view or shadow ray and thus achieve interactive performance.
Environmental Report 1996, Volume 2
Energy Technology Data Exchange (ETDEWEB)
Harrach, R.J.
1996-01-01
This is Volume 2 of the Lawrence Livermore National Laboratory`s (LLNL`s) annual Environmental Report 1996, prepared for the US Department of Energy. Volume 2 supports Volume 1 summary data and is essentially a detailed data report that provides individual data points, where applicable. Volume 2 includes information on monitoring of air, air effluents, sewerable water, surface water, ground water, soil and sediment, vegetation and foodstuff, environmental radiation, and quality assurance.
REFLECTION AND REFRACTION, VOLUME 2.
KLAUS, DAVID J.; AND OTHERS
THIS VOLUME 2 OF A TWO-VOLUME SET PROVIDES AUTOINSTRUCTION IN PHYSICS. THE UNITS COVERED IN THIS VOLUME ARE (1) REFLECTION OF LIGHT, (2) PHOTOMETRY, (3) POLARIZATION, (4) REFRACTION OF LIGHT, (5) SNELL'S LAW, (6) LENSES, FOCUS, AND FOCAL POINTS, (7) IMAGE FORMATION, AND (8) ABERRATIONS, THE EYE, AND MAGNIFICATION. THE INTRODUCTION AND UNITS ON…
Calculus Students' Understanding of Volume
Dorko, Allison; Speer, Natasha M.
2013-01-01
Researchers have documented difficulties that elementary school students have in understanding volume. Despite its importance in higher mathematics, we know little about college students' understanding of volume. This study investigated calculus students' understanding of volume. Clinical interview transcripts and written responses to volume…
Michaely, Henrik J; Morelli, John N; Budjan, Johannes; Riffel, Philipp; Nickel, Dominik; Kroeker, Randall; Schoenberg, Stefan O; Attenberger, Ulrike I
2013-08-01
value with CDT-VIBE in 10 of the 47 patients (21%). The CDT-VIBE is a robust approach allowing, for the first time, dynamic imaging of the upper abdomen with high temporal resolution and preservation of high spatial resolution.
Roche volume filling and the dissolution of open star clusters
Ernst, A; Just, A; Noel, T
2015-01-01
From direct N-body simulations we find that the dynamical evolution of star clusters is strongly influenced by the Roche volume filling factor. We present a parameter study of the dissolution of open star clusters with different Roche volume filling factors and different particle numbers. We study both Roche volume underfilling and overfilling models and compare with the Roche volume filling case. We find that in the Roche volume overfilling limit of our simulations two-body relaxation is no longer the dominant dissolution mechanism but the changing cluster potential. We call this mechnism "mass-loss driven dissolution" in contrast to "two-body relaxation driven dissolution" which occurs in the Roche volume underfilling regime. We have measured scaling exponents of the dissolution time with the two-body relaxation time. In this experimental study we find a decreasing scaling exponent with increasing Roche volume filling factor. The evolution of the escaper number in the Roche volume overfilling limit can be d...
Roche volume filling and the dissolution of open star clusters
Ernst, A.; Berczik, P.; Just, A.; Noel, T.
2015-08-01
From direct N-body simulations we find that the dynamical evolution of star clusters is strongly influenced by the Roche volume filling factor. We present a parameter study of the dissolution of open star clusters with different Roche volume filling factors and different particle numbers. We study both Roche volume underfilling and overfilling models and compare with the Roche volume filling case. We find that in the Roche volume overfilling limit of our simulations two-body relaxation is no longer the dominant dissolution mechanism but the changing cluster potential. We call this mechanism ``mass-loss driven dissolution'' in contrast to ``two-body relaxation driven dissolution'' which occurs in the Roche volume underfilling regime. We have measured scaling exponents of the dissolution time with the two-body relaxation time. In this experimental study we find a decreasing scaling exponent with increasing Roche volume filling factor. The evolution of the escaper number in the Roche volume overfilling limit can be described by a log-logistic differential equation. We report the finding of a resonance condition which may play a role for the evolution of star clusters and may be calibrated by the main periodic orbit in the large island of retrograde quasiperiodic orbits in the Poincaré surfaces of section. We also report on the existence of a stability curve which may be of relevance with respect to the structure of star clusters.
DEFF Research Database (Denmark)
Kiszka-Kanowitz, Marianne; Henriksen, Jens Henrik; Møller, Søren;
2001-01-01
: The close relation between the estimated blood volume in the thorax region and the central and arterial blood volume, obtained by the dynamic indicator dilution technique (r=0.87, PWhole-body scintigraphy showed altered blood volume distribution in the cirrhotic...
Volume of an Industrial Autoclave
Directory of Open Access Journals (Sweden)
Nicholas Madaffari
2010-01-01
Full Text Available We were able to determine the volume of an industrial autoclave sterilization tank using a technique learned in calculus. By measuring the dimensions of the tank and roughly estimating the equation of curvature at the ends of the tank, we were able to revolve half of the end of the tank around the x axis to get its fluid volume. Adding the two volumes of the ends and the volume of the cylindrical portion on the tank yielded the total volume.
McGee, William T
2009-01-01
Intravascular volume status and volume responsiveness continue to be important questions for the management of critically ill or injured patients. Goal-directed hemodynamic therapy has been shown to be of benefit to patients with severe sepsis and septic shock, acute lung injury and adult respiratory distress syndrome, and for surgical patients in the operating room. Static measures of fluid status, central venous pressure (CVP), and pulmonary artery occlusion pressure (PAOP) are not useful in predicting volume responsiveness. Stroke volume variation and pulse pressure variation related to changes in stroke volume during positive pressure ventilation predict fluid responsiveness and represent an evolving practice for volume management in the intensive care unit (ICU) or operating room. Adoption of dynamic parameters for volume management has been inconsistent. This manuscript reviews some of the basic physiology regarding the use of stroke volume variation to predict fluid responsiveness in the ICU and operating room. A management algorithm using this physiology is proposed for the critically ill or injured in various settings.
Basin stability in delayed dynamics
Leng, Siyang; Lin, Wei; Kurths, Jürgen
2016-02-01
Basin stability (BS) is a universal concept for complex systems studies, which focuses on the volume of the basin of attraction instead of the traditional linearization-based approach. It has a lot of applications in real-world systems especially in dynamical systems with a phenomenon of multi-stability, which is even more ubiquitous in delayed dynamics such as the firing neurons, the climatological processes, and the power grids. Due to the infinite dimensional property of the space for the initial values, how to properly define the basin’s volume for delayed dynamics remains a fundamental problem. We propose here a technique which projects the infinite dimensional initial state space to a finite-dimensional Euclidean space by expanding the initial function along with different orthogonal or nonorthogonal basis. A generalized concept of basin’s volume in delayed dynamics and a highly practicable calculating algorithm with a cross-validation procedure are provided to numerically estimate the basin of attraction in delayed dynamics. We show potential applicabilities of this approach by applying it to study several representative systems of biological or/and physical significance, including the delayed Hopfield neuronal model with multistability and delayed complex networks with synchronization dynamics.
Mikulica, Tomáš
2016-01-01
Cílem diplomové práce je popsat různé metody výpočtu globálního osvětlení scény včetně techniky Light Propagation Volumes. Pro tuto metodu jsou podrobně popsány všechny tři kroky výpočtu: injekce, propagace a vykreslení. Dále je navrženo několik vlastních rozšíření zlepšující grafickou kvalitu metody. Části návrhu a implementace jsou zaměřeny na popis scény, zobrazovacího systému, tvorby stínů, implementace metody Light Propagation Volumes a navržených rozšíření. Práci uzavírá měření, porovná...
Development of a balloon volume sensor for pulsating balloon catheters.
Nolan, Timothy D C; Hattler, Brack G; Federspiel, William J
2004-01-01
Helium pulsed balloons are integral components of several cardiovascular devices, including intraaortic balloon pumps (IABP) and a novel intravenous respiratory support catheter. Effective use of these devices clinically requires full inflation and deflation of the balloon, and improper operating conditions that lead to balloon under-inflation can potentially reduce respiratory or cardiac support provided to the patient. The goal of the present study was to extend basic spirographic techniques to develop a system to dynamically measure balloon volumes suitable for use in rapidly pulsating balloon catheters. The dynamic balloon volume sensor system (DBVSS) developed here used hot wire anemometry to measure helium flow in the drive line from console to catheter and integrated the flow to determine the volume delivered in each balloon pulsation. An important component of the DBVSS was an algorithm to automatically detect and adjust flow signals and measured balloon volumes in the presence of gas composition changes that arise from helium leaks occurring in these systems. The DBVSS was capable of measuring balloon volumes within 5-10% of actual balloon volumes over a broad range of operating conditions relevant to IABP and the respiratory support catheter. This includes variations in helium concentration from 70-100%, pulsation frequencies from 120-480 beats per minute, and simulated clinical conditions of reduced balloon filling caused by constricted vessels, increased driveline, or catheter resistance.
Free volume sizes in intercalated polyamide 6/clay nanocomposites
DEFF Research Database (Denmark)
Wiinberg, P.; Eldrup, Morten Mostgaard; Pedersen, N.J.
2005-01-01
The effect of incorporating modified clay into a polyamide 6 (PA6) matrix, on the free volume cavity sizes and the thermal and viscoelastic properties of the resulting nanocomposite, was studied with positron annihilation lifetime spectroscopy, differential scanning calorimetry and dynamic mechan...
Dynamic Recrystallization: The Dynamic Deformation Regime
Murr, L. E.; Pizaña, C.
2007-11-01
Severe plastic deformation (PD), especially involving high strain rates (>103 s 1), occurs through solid-state flow, which is accommodated by dynamic recrystallization (DRX), either in a continuous or discontinuous mode. This flow can be localized in shear instability zones (or adiabatic shear bands (ASBs)) with dimensions smaller than 5 μ, or can include large volumes with flow zone dimensions exceeding centimeters. This article illustrates these microstructural features using optical and electron metallography to examine a host of dynamic deformation examples: shaped charge jet formation, high-velocity and hypervelocity impact crater formation, rod penetration into thick targets (which includes rod and target DRX flow and mixing), large projectile-induced target plug formation and failure, explosive welding, and friction-stir welding and processing. The DRX is shown to be a universal mechanism that accommodates solid-state flow in extreme (or severe) PD regimes.
Dynamic Logics of Dynamical Systems
Platzer, André
2012-01-01
We survey dynamic logics for specifying and verifying properties of dynamical systems, including hybrid systems, distributed hybrid systems, and stochastic hybrid systems. A dynamic logic is a first-order modal logic with a pair of parametrized modal operators for each dynamical system to express necessary or possible properties of their transition behavior. Due to their full basis of first-order modal logic operators, dynamic logics can express a rich variety of system properties, including safety, controllability, reactivity, liveness, and quantified parametrized properties, even about relations between multiple dynamical systems. In this survey, we focus on some of the representatives of the family of differential dynamic logics, which share the ability to express properties of dynamical systems having continuous dynamics described by various forms of differential equations. We explain the dynamical system models, dynamic logics of dynamical systems, their semantics, their axiomatizations, and proof calcul...
Conference on Multibody Dynamics
Multibody Dynamics : Computational Methods and Applications
2014-01-01
By having its origin in analytical and continuum mechanics, as well as in computer science and applied mathematics, multibody dynamics provides a basis for analysis and virtual prototyping of innovative applications in many fields of contemporary engineering. With the utilization of computational models and algorithms that classically belonged to different fields of applied science, multibody dynamics delivers reliable simulation platforms for diverse highly-developed industrial products such as vehicle and railway systems, aeronautical and space vehicles, robotic manipulators, smart structures, biomechanical applications and nano-technologies. The chapters of this volume are based on the revised and extended versions of the selected scientific papers from amongst 255 original contributions that have been accepted to be presented within the program of the distinguished international ECCOMAS conference. It reflects state-of-the-art in the advances of multibody dynamics, providing excellent insight in the recen...
Excluded volume effect enhances the homology pairing of model chromosomes
Takamiya, Kazunori; Isami, Shuhei; Nishimori, Hiraku; Awazu, Akinori
2015-01-01
To investigate the structural dynamics of the homology pairing of polymers, we mod- eled the scenario of homologous chromosome pairings during meiosis in Schizosaccharomyces pombe, one of the simplest model organisms of eukaryotes. We consider a simple model consist- ing of pairs of homologous polymers with the same structures that are confined in a cylindrical container, which represents the local parts of chromosomes contained in an elongated nucleus of S. pombe. Brownian dynamics simulations of this model showed that the excluded volume effects among non-homological chromosomes and the transitional dynamics of nuclear shape serve to enhance the pairing of homologous chromosomes.
Excluded volume effect enhances the homology pairing of model chromosomes
Takamiya, Kazunori; Yamamoto, Keisuke; Isami, Shuhei; Nishimori, Hiraku; Awazu, Akinori
To investigate the structural dynamics of the homology pairing of polymers, we mod- eled the scenario of homologous chromosome pairings during meiosis in Schizosaccharomyces pombe, one of the simplest model organisms of eukaryotes. We consider a simple model consist- ing of pairs of homologous polymers with the same structures that are confined in a cylindrical container, which represents the local parts of chromosomes contained in an elongated nucleus of S. pombe. Brownian dynamics simulations of this model showed that the excluded volume effects among non-homological chromosomes and the transitional dynamics of nuclear shape serve to enhance the pairing of homologous chromosomes.
Institute of Scientific and Technical Information of China (English)
方顺
2012-01-01
This paper introduces the principles of Dynamic Segmentation, and taking the national highway network in Guangdong Province for example, by using route mileage as M - value of route system, with the traffic observed data collected from the annual traffic survey data being imported to the route system of national highway network as line events, the traffic volume data can match to the vector map, which could provide a basis for the further analysis on the highway network.%在介绍动态分段基本原理的基础上，以广东省普通国道网为例，将里程桩号作为路线系统的量测M值的校正参考依据，并把年度交调数据中路段交通流量观测值作为线事件引入国道网的路线系统中，实现了路段交通流量与空间矢量地图的匹配，为路网的进一步网络分析及研究决策提供了科学的参考依据。
Evolutionary dynamics of mammalian karyotypes
Directory of Open Access Journals (Sweden)
Carlo Alberto Redi
2012-12-01
Full Text Available This special volume of Cytogenetic and Genome Research (edited by Roscoe Stanyon, University of Florence and Alexander Graphodatsky, Siberian division of the Russian Academy of Sciences is dedicated to the fascinating long search of the forces behind the evolutionary dynamics of mammalian karyotypes, revealed after the hypotonic miracle of the 1950s....
DEFF Research Database (Denmark)
Aref, Hassan
2010-01-01
An IUTAM symposium with the title of this paper was held on October 12-16, 2008, in Lyngby and Copenhagen, Denmark, to mark the sesquicentennial of publication of Helmholtz's seminal paper on vortex dynamics. This volume contains the proceedings of the Symposium. The present paper provides...
FINITE VOLUME METHOD OF MODELLING TRANSIENT GROUNDWATER FLOW
Directory of Open Access Journals (Sweden)
N. Muyinda
2014-01-01
Full Text Available In the field of computational fluid dynamics, the finite volume method is dominant over other numerical techniques like the finite difference and finite element methods because the underlying physical quantities are conserved at the discrete level. In the present study, the finite volume method is used to solve an isotropic transient groundwater flow model to obtain hydraulic heads and flow through an aquifer. The objective is to discuss the theory of finite volume method and its applications in groundwater flow modelling. To achieve this, an orthogonal grid with quadrilateral control volumes has been used to simulate the model using mixed boundary conditions from Bwaise III, a Kampala Surburb. Results show that flow occurs from regions of high hydraulic head to regions of low hydraulic head until a steady head value is achieved.
Spatiotemporal heterogeneity of local free volumes in highly supercooled liquid
Shiba, Hayato; Kawasaki, Takeshi
2013-11-01
We discuss the spatiotemporal behavior of local density and its relation to dynamical heterogeneity in a highly supercooled liquid by using molecular dynamics simulations of a binary mixture with different particle sizes in two dimensions. To trace voids heterogeneously existing with lower local densities, which move along with the structural relaxation, we employ the minimum local density for each particle in a time window whose width is set along with the structural relaxation time. Particles subject to free volumes correspond well to the configuration rearranging region of dynamical heterogeneity. While the correlation length for dynamical heterogeneity grows with temperature decrease, no growth in the correlation length of heterogeneity in the minimum local density distribution takes place. A comparison of these results with those of normal mode analysis reveals that superpositions of lower-frequency soft modes extending over the free volumes exhibit spatial correlation with the broken bonds. This observation suggests a possibility that long-ranged vibration modes facilitate the interactions between fragile regions represented by free volumes, to induce dynamical correlations at a large scale.
Lagrangian Volume Deformations around Simulated Galaxies
Robles, S; Oñorbe, J; Martínez-Serrano, F J
2015-01-01
We present a detailed analysis of the local evolution of 206 Lagrangian Volumes (LVs) selected at high redshift around galaxy seeds, identified in a large-volume $\\Lambda$CDM hydrodynamical simulation. The LVs have a mass range of $1 - 1500 \\times 10^{10} M_\\odot$. We follow the dynamical evolution of the density field inside these initially spherical LVs from $z=10$ up to $z_{\\rm low}= 0.05$, witnessing highly non-linear, anisotropic mass rearrangements within them, leading to the emergence of the local cosmic web (CW). These mass arrangements have been analysed in terms of the reduced inertia tensor $I_{ij}^r$, focusing on the evolution of the principal axes of inertia and their corresponding eigen directions, and paying particular attention to the times when the evolution of these two structural elements declines. In addition, mass and component effects along this process have also been investigated. We have found that deformations are led by DM dynamics and they transform most of the initially spherical L...
Metric-Independent Volume-Forms in Gravity and Cosmology
Guendelman, Eduardo; Pacheva, Svetlana
2015-01-01
Employing alternative spacetime volume-forms (generally-covariant integration measure densities) independent of the pertinent Riemannian spacetime metric have profound impact in general relativity. Although formally appearing as "pure-gauge" dynamical degrees of freedom they trigger a number of remarkable physically important phenomena such as: (i) new mechanism of dynamical generation of cosmological constant; (ii) new type of "quintessential inflation" scenario in cosmology; (iii) non-singular initial "emergent universe" phase of cosmological evolution preceding the inflationary phase; (iv) new mechanism of dynamical spontaneous breakdown of supersymmetry in supergravity; (v) gravitational electrovacuum "bags". We study in some detail the properties, together with their canonical Hamiltonian formulation, of a class of generalized gravity-matter models built with two independent non-Riemannian volume-forms and discuss their implications in cosmology.
35th IMAC, A Conference and Exposition on Structural Dynamics 2017
Niezrecki, Christopher; Maio, Dario; Castellini, Paolo; Mains, Michael; Blough, JR
2017-01-01
Special Topics in Structural Dynamics, Volume 6: Proceedings of the 35th IMAC, A Conference and Exposition on Structural Dynamics, 2017, the sixth volume of ten 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: Experimental Methods Analytical Methods General Dynamics & Modal Analysis General Dynamics & System Identification Damage Detection .
Cosmological Measures without Volume Weighting
Page, Don N
2008-01-01
Many cosmologists (myself included) have advocated volume weighting for the cosmological measure problem, weighting spatial hypersurfaces by their volume. However, this often leads to the Boltzmann brain problem, that almost all observations would be by momentary Boltzmann brains that arise very briefly as quantum fluctuations in the late universe when it has expanded to a huge size, so that our observations (too ordered for Boltzmann brains) would be highly atypical and unlikely. Here it is suggested that volume weighting may be a mistake. Volume averaging is advocated as an alternative. One consequence would be a loss of the argument for eternal inflation.
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.
Schrijver, Carolus J.; Siscoe, George L.
2010-11-01
Volume 1: Preface; 1. Prologue Carolus J. Schrijver and George L. Siscoe; 2. Introduction to heliophysics Thomas J. Bogdan; 3. Creation and destruction of magnetic field Matthias Rempel; 4. Magnetic field topology Dana W. Longcope; 5. Magnetic reconnection Terry G. Forbes; 6. Structures of the magnetic field Mark B. Moldwin, George L. Siscoe and Carolus J. Schrijver; 7. Turbulence in space plasmas Charles W. Smith; 8. The solar atmosphere Viggo H. Hansteen; 9. Stellar winds and magnetic fields Viggo H. Hansteen; 10. Fundamentals of planetary magnetospheres Vytenis M. Vasyliūnas; 11. Solar-wind magnetosphere coupling: an MHD perspective Frank R. Toffoletto and George L. Siscoe; 12. On the ionosphere and chromosphere Tim Fuller-Rowell and Carolus J. Schrijver; 13. Comparative planetary environments Frances Bagenal; Bibliography; Index. Volume 2: Preface; 1. Perspective on heliophysics George L. Siscoe and Carolus J. Schrijver; 2. Introduction to space storms and radiation Sten Odenwald; 3. In-situ detection of energetic particles George Gloeckler; 4. Radiative signatures of energetic particles Tim Bastian; 5. Observations of solar and stellar eruptions, flares, and jets Hugh Hudson; 6. Models of coronal mass ejections and flares Terry Forbes; 7. Shocks in heliophysics Merav Opher; 8. Particle acceleration in shocks Dietmar Krauss-Varban; 9. Energetic particle transport Joe Giacalone; 10. Energy conversion in planetary magnetospheres Vytenis Vasyliūnas; 11. Energization of trapped particles Janet Green; 12. Flares, CMEs, and atmospheric responses Tim Fuller-Rowell and Stanley C. Solomon; 13. Energetic particles and manned spaceflight 358 Stephen Guetersloh and Neal Zapp; 14. Energetic particles and technology Alan Tribble; Appendix I. Authors and editors; List of illustrations; List of tables; Bibliography; Index. Volume 3: Preface; 1. Interconnectedness in heliophysics Carolus J. Schrijver and George L. Siscoe; 2. Long-term evolution of magnetic activity of Sun
Directory of Open Access Journals (Sweden)
Cooch, E. G.
2004-06-01
focused on estimation of survival rate (arguably, use of data from marked individuals has been used for estimation of survival more than any other parameter, save perhaps abundance, it is only one of many transitions in the life cycle. Others discussed include transitions between age or size classes, breeding states, and physical locations. The demographic consequences of these transitions can be captured by matrix population models, and such models provide a natural link connecting multi–stage mark–recapture methods and population dynamics. The utility of the matrix approach for both prospective, and retrospective, analysis of variation in the dynamics of populations is well–known; such comparisons of results of prospective and retrospective analysis is fundamental to considerations of conservation management (sensu Caswell, 2000. What is intriguing is the degree to which these methods can be combined, or contrasted, with more direct estimation of one or more measures of the trajectory of a population (e.g., Sandercock & Beissinger, 2002. The five additional papers presented in the population dynamics session clearly reflected these considerations. In particular, the three papers submitted for this volume indicate the various ways in which complex empirical data can be analyzed, and often combined with more classical modeling approaches, to provide more robust insights to the dynamics of the study population. The paper by Francis & Saurola (2004 is an example of rigorous analysis and modeling applied to a large, carefully collected dataset from a long–term study of the biology of the Tawny Owl. Using a combination of live encounters and dead recoveries, the authors were able to separate the relative contributions of various processes (emigration, mortality on variation in survival rates. These analyses were combined with periodic matrix models to explore comparisons of direct estimation of changes in population size (based on both census and mark
Volume and Surface-Enhanced Volume Negative Ion Sources
Stockli, M P
2013-01-01
H- volume sources and, especially, caesiated H- volume sources are important ion sources for generating high-intensity proton beams, which then in turn generate large quantities of other particles. This chapter discusses the physics and technology of the volume production and the caesium-enhanced (surface) production of H- ions. Starting with Bacal's discovery of the H- volume production, the chapter briefly recounts the development of some H- sources, which capitalized on this process to significantly increase the production of H- beams. Another significant increase was achieved in the 1990s by adding caesiated surfaces to supplement the volume-produced ions with surface-produced ions, as illustrated with other H- sources. Finally, the focus turns to some of the experience gained when such a source was successfully ramped up in H- output and in duty factor to support the generation of 1 MW proton beams for the Spallation Neutron Source.
'Shape Dynamics': Foundations Reassessed
Anderson, Edward
2015-01-01
`Shape dynamics' is meant here in the sense of a type of conformogeometrical reformulation of GR, some of which have of late been considered as generalizations of or alternatives to GR. This note concerns in particular cases based on the notion of volume-preserving conformal transformations (VPCTs), in the sense of preserving a solitary global volume of the universe degree of freedom. The extent to which various ways of modelling VPCTs make use of group theory at all, in a congruous manner, and with minimal departure from standard Lie group theory, is considered. This points to changing conception of VPCTs from the current finite integral implementation to an infinitesimal differential implementation (or to avoiding using them at all). Some useful observations from flat-space conformal groups (well-known from CFT) concerning the existence or otherwise of VPCT groups are also provided.
Helicopter Dynamic Performance Program. Volume 2. User’s Manual
1980-07-01
the calculated power required plus this increment exceeds the power input in locatin 81, the power level specified in 81 will be used. 207: Auxiliary...hover height. This cordi ~ion also prevails for the 1.2 and 1.3 options. The non-ntirized points reflected on the H-V diagram drawn only r.;flect the...takeoff distance plus the aircraft length. It should be noted that landing distances must also be considered in the determination of the paved field size
Aircraft Landing Dynamic Analysis. Volume 2. Computer Program
1988-11-04
VIGA = 0.0 INIT 90 V2GA = 0.0 INIT 91 V3GA = 0.0 INIT 92 PHIHKR = PHIHKO / 57.29578 INIT 93 IF (NBE) 30, 130, 30 INIT 94 30 VBA1 = VB(1) + GAMB(1,I...VIL INIT162 V2L = GAMB(3,I) * LT2(I) + V2L INIT163 V3L = GAMB(3,I) * LT3(I) + V3L INIT164 VHL = GAMB(3,I) * LH(I) + VHL INIT165 VIGA = GBAG1(3,I...GXIA1(I) + ViGA INIT166 V2GA = GBAG2(3,I) * GXIA2(I) + V2GA INIT167 140 V3GA = GBAG3(3,I) * GXIA3(I) + V3GA lNiTI68 Vl = - VIL - VIGA - VIQB - WC13
A Dynamical Mechanism for Large Volumes with Consistent Couplings
Abel, Steven
2016-01-01
A mechanism for addressing the 'decompactification problem' is proposed, which consists of balancing the vacuum energy in Scherk-Schwarzed theories against contributions coming from non- perturbative physics. Universality of threshold corrections ensures that, in such situations, the stable minimum will have consistent gauge couplings for any gauge group that shares the same N = 2 beta function for the bulk excitations as the gauge group that takes part in the minimisation. Scherk- Schwarz compactification from 6D to 4D in heterotic strings is discussed explicitly, together with two alternative possibilities for the non-perturbative physics, namely metastable SQCD vacua and a single gaugino condensate. In the former case, it is shown that modular symmetries gives various consistency checks, and allow one to follow soft-terms, playing a similar role to R-symmetry in global SQCD. The latter case is particularly attractive when there is nett Bose-Fermi degeneracy in the massless sector. In such cases, because th...
Engineering Applications of Computational Fluid Dynamics: Volume 1
Directory of Open Access Journals (Sweden)
Maher A.R. Sadiq Al-Baghdadi
2013-01-01
Full Text Available Chapter 1: Filtered Density Function as a Modern CFD Tool. N. Ansari, F.A. Jaberi, M.R.H. Sheikhi, P. Givi Chapter 2: CFD Applications in Steam Boilers. N. Nikolopoulos, A. Nikolopoulos, E. Karambinis, M. Agraniotis, P. Grammelis, E. Kakaras Chapter 3: CFD Simulation on Human-Environment System. Shengwei Zhu Chapter 4: CFD Applications in Membrane Technology by Finite Element Analysis. José M. Gozálvez-Zafrilla, Asunción Santafé-Moros Chapter 5: CFD Modelling of Stirred Tanks. Z. Driss, M. Ammar, W. Chtourou, M.S. Abid Chapter 6: CFD Modeling and Simulations: Horizontal Deep Drilling Process and Filter Cake Formation. Mohd A. Kabir, Isaac K. Gamwo Chapter 7: CFD Simulation of Phase Particle Entrapment. Peymani F. Y., Ganbari S. A., Liu Y., Hayatdavoudi A. Chapter 8: Simulation of Low-Btu Syngas Combustion in Trapped Vortex Combustor. Khaled Zbeeb, Chaouki Ghenai Chapter 9: Experimental, Analytical and Numerical Investigation of a Swirling Submerged Jet Flow. H. Alighanbari, M. R. Amiralaei, S. Savtchenko Chapter 10: CFD Simulations of Two-Phase Flow. Yu Zhang Chapter 11: CFD Simulation of Syntrophic Anaerobic Digestion of Volatile Fatty Acids in a Continuous Stirred Reactor. T. Amani, S.M. Mousavi, M. Nosrati
A dynamical mechanism for large volumes with consistent couplings
Abel, Steven
2016-11-01
A mechanism for addressing the "decompactification problem" is proposed, which consists of balancing the vacuum energy in Scherk-Schwarzed theories against contributions coming from non-perturbative physics. Universality of threshold corrections ensures that, in such situations, the stable minimum will have consistent gauge couplings for any gauge group that shares the same N = 2 beta function for the bulk excitations as the gauge group that takes part in the minimisation. Scherk-Schwarz compactification from 6D to 4D in heterotic strings is discussed explicitly, together with two alternative possibilities for the non-perturbative physics, namely metastable SQCD vacua and a single gaugino condensate. In the former case, it is shown that modular symmetries gives various consistency checks, and allow one to follow soft-terms, playing a similar role to R-symmetry in global SQCD. The latter case is particularly attractive when there is nett Bose-Fermi degeneracy in the massless sector. In such cases, because the original Casimir energy is generated entirely by excited and/or non-physical string modes, it is completely immune to the non-perturbative IR physics. Such a separation between UV and IR contributions to the potential greatly simplifies the analysis of stabilisation, and is a general possibility that has not been considered before.
Probabilistic Modeling of Aircraft Trajectories for Dynamic Separation Volumes
Lewis, Timothy A.
2016-01-01
With a proliferation of new and unconventional vehicles and operations expected in the future, the ab initio airspace design will require new approaches to trajectory prediction for separation assurance and other air traffic management functions. This paper presents an approach to probabilistic modeling of the trajectory of an aircraft when its intent is unknown. The approach uses a set of feature functions to constrain a maximum entropy probability distribution based on a set of observed aircraft trajectories. This model can be used to sample new aircraft trajectories to form an ensemble reflecting the variability in an aircraft's intent. The model learning process ensures that the variability in this ensemble reflects the behavior observed in the original data set. Computational examples are presented.
Dynamic Response of Reinforced Soil Systems. Volume 1. Report
1993-03-01
accomplished by modeling explosive energy. The heat of detonation of I gram (0.0022 pounds) of cyclotrimethylenetrinitramine (RDX) is equal to the heat ... of detonation of 1.14 gram (0.0025 pounds) of TNT (Reference 77). It was originally intended to accelerate all models to 30 g and to calculate and
Spacecraft dynamics characterization and control system failure detection, volume 1
1992-07-01
The work under this grant has been directed to two aspects of the control of flexible spacecraft: (1) the modeling of deployed or erected structures including nonlinear joint characteristics; and (2) the detection and isolation of failures of the components of control systems for large space structures. The motivation for the first of these research tasks is the fact that very large assemblies in space will have to be built or deployed in situ. A likely scenario is, in fact, a combination of these wherein modules which are folded for transportation into orbit are erected to their final configuration and then jointed with other such erected modules to form the full assembly. Any such erectable modules will have joints. It remains to be seen whether or not joints designed for operational assemblies will have nonlinear properties, but it seems prudent to develop a methodology for dealing with that possibility. The motivation for the second of these research tasks is the fact that we foresee large assemblies in space which will require active control to damp vibrations and/or hold a desired shape. Lightweight structures will be very flexible, with many elastic modes having very low frequencies. In order to control these modes well, the control system will likely require many sensors and many actuators, probably distributed over much of the structure. The combination of a large number of control system components with long operational periods virtually guarantees that these systems will suffer control system component failures during operation. The control system must be designed to tolerate failures of some sensors and actuators, and still be able to continue to perform its function.
A Dynamic Analysis of the Medium Tank Battalion. Volume I
1978-06-01
the U.S. Army might employ the Medium Tank Battalion as part of a Heavy Division would te the Midale East and North Africa . The Study had insufficient...V t C4 1 4 . N_ __14 4 in in In AAIn 4jJ 0% W ~ %%I- 0 0% 9 0 %o in o 0% OD - uf tfl PIb u .40 0 4I) >. -A V) 4.0% %0 1D~4 in E4) d) N 0 Ch QU W %0
Dynamic Displays for Tactical Planning. Volume 3. Software Documentation
1979-12-01
7 STAI T=EVTPTR C *~*SHIF! MoF I(- MAKE ThUM 16. MCTIUA BLOCK FCR GREEN ACTIi’ KEL_’f9.J PTRPlP=LF-LPTR+lsLJSLZ-1 ACTPlk=MDF(PTRPTk’) ST ART =ACTPTR 8...IN2 9 ML Z LSP= (’fN2-~iN 0* 12000+ %IL2-rlL I IF(LSP.GT.4C,)G~i TO 300 DO 315 K~lv400 315 C0iINUE Ii-( lATT (1).E.0L, TO J12 IU-IATT(1).N-.36.CR.IATT(3...0 ?nl IF ( lATT (i).NL.-) GO TO 30 KEY=ITEM P +34 GO TO 1000 3, It- ( IA TT 1l).Nl:.32) GO TC 40 u&EY=130kJO*IATI (; GL, TO 1000 4,j IF IIATI1.NE.30
Quantification of cardiopulmonary blood volume turnover using dynamic PET
DEFF Research Database (Denmark)
Harms, Hans; Tolbod, Lars Poulsen; Kero, Tanja;
: MPTT progressively increased with disease severity during stress (mean MPTT±SD of 0.142±0.051 min, 0.176±0.042 min, 0.186±0.040 min and 0.248±0.077 min for groups 1 to 4, ANOVA p....237±0.059 min for groups 1 to 4, ANOVA pANOVA pANOVA p
PDLE: Sustaining Professionalism. Volume 3
Byrd, Patricia, Ed.; Nelson, Gayle, Ed.
2003-01-01
This third volume looks at ways that seasoned professionals continue to develop throughout their careers. The text includes descriptive accounts of professionals seeking to enhance their careers while remaining inspired to continue to develop professionally. This volume reveals how personal and professional lives are entwined. It proves that TESOL…
African Journals Online (AJOL)
PROF. EZECHUKWU
2013-11-24
Nov 24, 2013 ... sleep. There was also increase in both frequency of uri- nation and volume of urine voided; from1- 2 times to ... phagia, fever, head trauma, chronic cough, weight loss, ... water deprivation at 15Kg. Total volume of urine voided.
Finding related functional neuroimaging volumes
DEFF Research Database (Denmark)
Nielsen, Finn Årup; Hansen, Lars Kai
2004-01-01
We describe a content-based image retrieval technique for finding related functional neuroimaging experiments by voxelization of sets of stereotactic coordinates in Talairach space, comparing the volumes and reporting related volumes in a sorted list. Voxelization is accomplished by convolving each...
Discretized Volumes in Numerical Methods
Antal, Miklós
2007-01-01
We present two techniques novel in numerical methods. The first technique compiles the domain of the numerical methods as a discretized volume. Congruent elements are glued together to compile the domain over which the solution of a boundary value problem is sought. We associate a group and a graph to that volume. When the group is symmetry of the boundary value problem under investigation, one can specify the structure of the solution, and find out if there are equispectral volumes of a given type. The second technique uses a complex mapping to transplant the solution from volume to volume and a correction function. Equation for the correction function is given. A simple example demonstrates the feasibility of the suggested method.
Biochemical kinetics in changing volumes.
Pawłowski, Piotr H; Zielenkiewicz, Piotr
2004-01-01
The need of taking into account the change of compartment volume when developing chemical kinetics analysis inside the living cell is discussed. Literature models of a single enzymatic Michaelis-Menten process, glycolytic oscillations, and mitotic cyclin oscillations were tested with appropriate theoretical extension in the direction of volume modification allowance. Linear and exponential type of volume increase regimes were compared. Due to the above, in a growing cell damping of the amplitude, phase shift, and time pattern deformation of the metabolic rhythms considered were detected, depending on the volume change character. The performed computer simulations allow us to conclude that evolution of the cell volume can be an essential factor of the chemical kinetics in a growing cell. The phenomenon of additional metabolite oscillations caused by the periodic cell growth and division was theoretically predicted and mathematically described. Also, the hypothesis of the periodized state in the growing cell as the generalization of the steady-state was formulated.
Animation framework using volume visualization
Fang, Wenxuan; Wang, Hongli
2004-03-01
As the development of computer graphics, scientific visualization and advanced imaging scanner and sensor technology, high quality animation making of volume data set has been a challenging in industries. A simple animation framework by using current volume visualization techniques is proposed in this paper. The framework consists of two pipelines: one is surface based method by using marching cubes algorithm, the other is volume rendering method by using shear-warp method. The volume visualization results can not only be used as key frame sources in the animation making, but also can be directly used as animation when the volume visualization is in stereoscopic mode. The proposed framework can be applied into fields such as medical education, film-making and archaeology.
Institute of Scientific and Technical Information of China (English)
张小伟; 王淑香; 王岩; 马玲
2016-01-01
目的探讨应用灰色动态 GM（1，1）模型，分析和预测常态下承德市中心血站血液品种采集数量的动态发展变化趋势，根据模型的应用效果做出定量预测。方法根据承德市中心血站2004年1月～2013年12月的全血（400 ml）（人次）、单采少白血小板（人份）血液品种年采集数据，将2013年预测值与实际值比较，检验模型的预测能力，同时分析2014～2016年血液采集数量。结果以上两类血液采集品种数量灰色动态 GM（1，1）模型的 Y（t）后验差比（均方差）C均＜0.35，小误差概率P值均为1。精度均为优，用于血液采集量预测的效果好。结论承德市中心血站以上两类血液采集品种数量呈逐渐增高趋势。灰色系统一阶模型 GM（1，1）作为一种新型预测模型，能够在常态下合理预测采供血系统血液采集量。%Objective To explore the application of dynamic grey GM (1,1)modeling,analyse and forecast varieties of blood collection volume for central blood bank of Chengde in Hebei Province,under normal dynamic development trends,and make quantitative predictions according to the model’s application.Methods According to the blood collection data of whole blood,single white blood platelet (person-portion)in the blood Bank of Chengde city fom January 2004 to December 2013 (400 ml/people),and in order to test predictive ability of the model by comparing the forecast value with the actual value in 2013.At the same time,analysed blood collection value in 2014 to 2016.Results The above two types of blood collection number grey GM (1,1)model Y (t)posterior difference (standard deviation)C<0.35,small error probability P was 1.Ac-curacy was excellent,good for prediction of blood collection.Conclusion These two categories of blood collecting species in Central Blood Bank of Chengde increased gradually.Grey model GM (1,1)as a new prediction model can forecast reasonably clinical blood
Institute of Scientific and Technical Information of China (English)
于梅艳; 时惠平; 李春东; 熊明辉; 毕永民; 郭薇; 马晓璇
2012-01-01
uterus was imaged, and registration could be completed in all cases. The time-density curve ascended quickly. The cervical cancer could be visualized on color maps, and was significantly higher than the surrounding normal tissue. The AF of cervix cancer (255. 42±28. 14) ml/min/l00ml was significantly higher than that of normal tissue (168. 34±7. 49) ml/min/lOOml ( t =3. 189, F<0. 05), and could be visualized on colored perfusion maps. Conclusion The 640-slice CT cervical cancer dynamic volume CT perfusion has good maneuver ability and feasibility. As a comprehensive imaging technique in the evaluation of cervical cancer, CT perfusion can evaluate the hemo-dynamic changes of cervical cancer and is a useful complement to conventional CT scan.
LLE Review: Quarterly report, July--September 1994. Volume 60
Energy Technology Data Exchange (ETDEWEB)
Knauer, J.P. [ed.
1994-12-31
This volume contains articles on efficient generation of second-harmonic radiation from short-pulse lasers; calculation of the stabilization cutoff wave numbers for the Rayleigh-Taylor instability; a high-frequency silicon optical modulator; the angular dependence of stimulated Brillouin scattering; and femtosecond dynamics of ladder polymers. Three of these articles--second-harmonic generation, Rayleigh-Taylor cutoff wave numbers, and angular dependence of Brillouin scattering--are directly related to the OMEGA Upgrade, currently under construction. A summary of the status of the OMEGA Upgrade laser facility and the NLUF News for FY94 are included in this volume.
Xie, Huimin
The following sections are included: * Definition of Dynamical Languages * Distinct Excluded Blocks * Definition and Properties * L and L″ in Chomsky Hierarchy * A Natural Equivalence Relation * Symbolic Flows * Symbolic Flows and Dynamical Languages * Subshifts of Finite Type * Sofic Systems * Graphs and Dynamical Languages * Graphs and Shannon-Graphs * Transitive Languages * Topological Entropy
[Dynamic lung hyperinflation and its clinical implication in COPD].
O'donnell, D-E
2008-12-01
Static lung hyperinflation is defined as the elevation of end- expiratory lung volume above its predicted value, with no increase in end-expiratory alveolar pressure, which remains equal to atmospheric pressure. Dynamic hyperinflation is the transient increase of this volume above the relaxation volume. In patients with COPD, dynamic hyperinflation is mainly determined by the mechanical properties of the respiratory system. Its measurement relies on plethysmography and, during exercise, inspiratory capacity. During exercise, dynamic hyperinflation attenuates expiratory flow limitation but increases the inspiratory loading and induces functional weakness of the diaphragm. It also has haemodynamic consequences and results in more rapid, shallow breathing and progressive reduction in dynamic lung compliance. These events explain exercise intolerance. Several approaches may help combat dynamic hyperinflation and its deleterious clinical effects: bronchodilators, hyperoxia, helium-oxygen mixtures, lung volume reduction surgery...
Rho, Mannque
2008-01-01
This is the sequel to the first volume to treat in one effective field theory framework the physics of strongly interacting matter under extreme conditions. This is vital for understanding the high temperature phenomena taking place in relativistic heavy ion collisions and in the early Universe, as well as the high-density matter predicted to be present in compact stars. The underlying thesis is that what governs hadronic properties in a heat bath and/or a dense medium is hidden local symmetry which emerges from chiral dynamics of light quark systems and from the duality between QCD in 4D and
Liang, Xuecheng
Dynamic hardness (Pd) of 22 different pure metals and alloys having a wide range of elastic modulus, static hardness, and crystal structure were measured in a gas pulse system. The indentation contact diameter with an indenting sphere and the radius (r2) of curvature of the indentation were determined by the curve fitting of the indentation profile data. r 2 measured by the profilometer was compared with that calculated from Hertz equation in both dynamic and static conditions. The results indicated that the curvature change due to elastic recovery after unloading is approximately proportional to the parameters predicted by Hertz equation. However, r 2 is less than the radius of indenting sphere in many cases which is contradictory to Hertz analysis. This discrepancy is believed due to the difference between Hertzian and actual stress distributions underneath the indentation. Factors which influence indentation elastic recovery were also discussed. It was found that Tabor dynamic hardness formula always gives a lower value than that directly from dynamic hardness definition DeltaE/V because of errors mainly from Tabor's rebound equation and the assumption that dynamic hardness at the beginning of rebound process (Pr) is equal to kinetic energy change of an impact sphere over the formed crater volume (Pd) in the derivation process for Tabor's dynamic hardness formula. Experimental results also suggested that dynamic to static hardness ratio of a material is primarily determined by its crystal structure and static hardness. The effects of strain rate and temperature rise on this ratio were discussed. A vacuum rotating arm apparatus was built to measure Pd at 70, 127, and 381 mum sphere sizes, these results exhibited that Pd is highly depended on the sphere size due to the strain rate effects. P d was also used to substitute for static hardness to correlate with abrasion and erosion resistance of metals and alloys. The particle size effects observed in erosion were
Comparison of methods to quantify volume during resistance exercise.
McBride, Jeffrey M; McCaulley, Grant O; Cormie, Prue; Nuzzo, James L; Cavill, Michael J; Triplett, N Travis
2009-01-01
The purpose of this investigation was to compare 4 different methods of calculating volume when comparing resistance exercise protocols of varying intensities. Ten Appalachian State University students experienced in resistance exercise completed 3 different resistance exercise protocols on different days using a randomized, crossover design, with 1 week of rest between each protocol. The protocols included 1) hypertrophy: 4 sets of 10 repetitions in the squat at 75% of a 1-repetition maximum (1RM) (90-second rest periods); 2) strength: 11 sets of 3 repetitions at 90% 1RM (5-minute rest periods); and 3) power: 8 sets of 6 repetitions of jump squats at 0% 1RM (3-minute rest periods). The volume of resistance exercise completed during each protocol was determined with 4 different methods: 1) volume load (VL) (repetitions [no.] x external load [kg]); 2) maximum dynamic strength volume load (MDSVL) (repetitions [no.] x [body mass--shank mass (kg) + external load (kg)]); 3) time under tension (TUT) (eccentric time +milliseconds] + concentric time +milliseconds]); and 4) total work (TW) (force [N] x displacement [m]). The volumes differed significantly (p , 0.05) between hypertrophy and strength in comparison with the power protocol when VL and MDSVL were used to determine the volume of resistance exercise completed. Furthermore, significant differences in TUT existed between all 3 resistance exercise protocols. The TW calculated was not significantly different between the 3 protocols. These data imply that each method examined results in substantially different values when comparing various resistance exercise protocols involving different levels of intensity.
Cortisol, Cytokines, and Hippocampal Volume in the Elderly
Directory of Open Access Journals (Sweden)
Keith Daniel Sudheimer
2014-07-01
Full Text Available Separate bodies of literature report that elevated pro-inflammatory cytokines and cortisol negatively affect hippocampal structure and cognitive functioning, particularly in older adults. Although interactions between cytokines and cortisol occur through a variety of known mechanisms, few studies consider how their interactions affect brain structure. In this preliminary study, we assess the impact of interactions between circulating levels of IL-1Beta, IL-6, IL-8, IL-10, IL-12, TNF-alpha, and waking cortisol on hippocampal volume. Twenty-eight community-dwelling older adults underwent blood draws for quantification of circulating cytokines and saliva collections to quantify the cortisol awakening response. Hippocampal volume measurements were made using structural magnetic resonance imaging. Elevated levels of waking cortisol in conjunction with higher concentrations of IL-6 and TNF-alpha were associated with smaller hippocampal volumes. In addition, independent of cortisol, higher levels of IL-1beta and TNF-alpha were also associated with smaller hippocampal volumes. These data provide preliminary evidence that higher cortisol, in conjunction with higher IL-6 and TNF-alpha, are associated with smaller hippocampal volume in older adults. We suggest that the dynamic balance between the hypothalamic-pituitary adrenal axis and inflammation processes may explain hippocampal volume reductions in older adults better than either set of measures do in isolation.
Tikhonov, A V
2006-01-01
We consider a sphere of 7.5 Mpc radius, which contains 355 galaxies with accurately measured distances, to detect the nearest empty volumes. Using a simple void detection algorithm, we found six large (mini)voids in Aquila, Eridanus, Leo, Vela, Cepheus and Octans, each of more than 30 Mpc^3. Besides them, 24 middle-size "bubbles" of more than 5 Mpc^3 volume are detected, as well as 52 small "pores". The six largest minivoids occupy 58% of the considered volume. Addition of the bubbles and pores to them increases the total empty volume up to 75% and 81%, respectively. The detected local voids look like oblong potatoes with typical axial ratios b/a = 0.75 and c/a = 0.62 (in the triaxial ellipsoide approximation). Being arranged by the size of their volume, local voids follow power law of volumes-rankes dependence. A correlation Gamma-function of the Local Volume galaxies follows a power low with a formally calculated fractal dimension D = 1.5. We found that galaxies surrounding the local minivoids do not differ...
Molecular mobility with respect to accessible volume in Monte Carlo lattice model for polymers
Diani, J.; Gilormini, P.
2017-02-01
A three-dimensional cubic Monte Carlo lattice model is considered to test the impact of volume on the molecular mobility of amorphous polymers. Assuming classic polymer chain dynamics, the concept of locked volume limiting the accessible volume around the polymer chains is introduced. The polymer mobility is assessed by its ability to explore the entire lattice thanks to reptation motions. When recording the polymer mobility with respect to the lattice accessible volume, a sharp mobility transition is observed as witnessed during glass transition. The model ability to reproduce known actual trends in terms of glass transition with respect to material parameters, is also tested.
Plasma volume changes during hypoglycaemia
DEFF Research Database (Denmark)
Hilsted, J; Frandsen, Henrik Lund; Christensen, N J
1991-01-01
-induced hypoglycaemia with total autonomic blockade (alpha-adrenoceptor blockade combined with beta-adrenoceptor blockade and atropine); and insulin-induced hypoglycaemia without any autonomic blockade. In the experiments without autonomic blockade the peripheral venous hematocrit increased, plasma volume decreased......, intravascular albumin content decreased and the transcapillary escape rate of albumin increased. In both experiments with autonomic blockade the increase in venous haematocrit was abolished, yet plasma volume decreased, intravascular albumin content decreased and the transcapillary escape rate of albumin...... increased in these experiments. Thus, the changes in plasma volume and composition in response to hypoglycaemia are due to the combined actions of adrenaline and of insulin....
Plasma volume changes during hypoglycaemia
DEFF Research Database (Denmark)
Hilsted, J; Bendtsen, F; Christensen, N J
1990-01-01
To investigate whether previously reported changes in venous blood volume and composition induced by acute hypoglycaemia in humans are representative for the entire body we measured erythrocyte 51Cr content, haematocrit, plasma volume, intravascular albumin content and transcapillary escape rate...... of albumin in arterial and venous blood in seven healthy subjects before and during insulin-induced hypoglycaemia. In both vascular sites blood 51Cr content and the haematocrit increased, plasma volume and intravascular albumin content decreased and the transcapillary escape rate of albumin increased during...
10 CFR 63.332 - Representative volume.
2010-01-01
... 10 Energy 2 2010-01-01 2010-01-01 false Representative volume. 63.332 Section 63.332 Energy... Protection Standards § 63.332 Representative volume. (a) The representative volume is the volume of ground... radionuclides released from the Yucca Mountain disposal system that will be in the representative volume....
Bare-Hand Volume Cracker for Raw Volume Data Analysis
Directory of Open Access Journals (Sweden)
Bireswar Laha
2016-09-01
Full Text Available Analysis of raw volume data generated from different scanning technologies faces a variety of challenges, related to search, pattern recognition, spatial understanding, quantitative estimation, and shape description. In a previous study, we found that the Volume Cracker (VC 3D interaction (3DI technique mitigated some of these problems, but this result was from a tethered glove-based system with users analyzing simulated data. Here, we redesigned the VC by using untethered bare-hand interaction with real volume datasets, with a broader aim of adoption of this technique in research labs. We developed symmetric and asymmetric interfaces for the Bare-Hand Volume Cracker (BHVC through design iterations with a biomechanics scientist. We evaluated our asymmetric BHVC technique against standard 2D and widely used 3D interaction techniques with experts analyzing scanned beetle datasets. We found that our BHVC design significantly outperformed the other two techniques. This study contributes a practical 3DI design for scientists, documents lessons learned while redesigning for bare-hand trackers, and provides evidence suggesting that 3D interaction could improve volume data analysis for a variety of visual analysis tasks. Our contribution is in the realm of 3D user interfaces tightly integrated with visualization, for improving the effectiveness of visual analysis of volume datasets. Based on our experience, we also provide some insights into hardware-agnostic principles for design of effective interaction techniques.
Spin Dynamics in Confined Magnetic Structures III
Hillebrands, Burkard
2006-01-01
This third volume of Spin Dynamics in Confined Magnetic Structures addresses central aspects of spin-dynamic phenomena, including recent new developments, on a tutorial level. Researchers will find a comprehensive compilation of the current work in the field. Introductory chapters help newcomers to understand the basic concepts. The more advanced chapters give the current state of the art of spin dynamic issues ranging from the femtosecond to the microsecond regime. This volume concentrates on new experimental techniques such as ferromagnetic-resonance-force microscopy and two-photon photoemission, as well as on aspects of precessional switching, spin-wave excitation, vortex dynamics, spin relaxation, domain-wall dynamics in nanowires and their applications to magnetic logic devices. An important chapter is devoted to the presently very hot subject of the spin-transfer torque, combining the physics of electronic transport and micromagnetics. The comprehensive presentation of these developments makes this volu...
Impact of 8-week endurance training on qualitative and quantitative parameters of stroke volume
Directory of Open Access Journals (Sweden)
Suzana Pustivšek
2014-08-01
Full Text Available Background: Dynamics of stroke volume during increasing progressive load varies widely among individuals. The data of current studies describing the impact of long-term endurance training on the dynamics of cardiac stroke volume are conflicting. The purpose of this study was to evaluate the impact of 8-week endurance training on the dynamics of stroke volume and some quantitative features of cardiac function in recreational female runners.Methods: Measurements were performed in the physiological laboratory at the Institute of Sport, Faculty of Sport in Ljubljana. CosmedK4b2 equipment that allows continuous “on-line”, “breath-by-breath” monitoring of oxygen consumption and gases in exhaled air was used. Cardiac output was calculated by the method described by Stringer et al.Results: The results showed a significant increase in stroke volume at rest and during the first two minutes of the test. Maximum stroke volume did not increase, but there was a decrease in heart rate during maximal stroke volume from 126.65 (± 27.14 to 120.15 (± 26.56 beats per minute. The dynamics of stroke volume in a majority of participants did not change. The most common dynamics of stroke volume before and after test was plateau dynamics. The training resulted in an increase in running endurance and the average increase in running speed during the final test by 4.41 % (± 4.62.Conclusion: The exercise resulted in minimal changes in cardiac function and a significant improvement in endurance parameters.
Chaotic dynamics in nanoscale NbO2 Mott memristors for analogue computing
Kumar, Suhas; Strachan, John Paul; Williams, R. Stanley
2017-08-01
At present, machine learning systems use simplified neuron models that lack the rich nonlinear phenomena observed in biological systems, which display spatio-temporal cooperative dynamics. There is evidence that neurons operate in a regime called the edge of chaos that may be central to complexity, learning efficiency, adaptability and analogue (non-Boolean) computation in brains. Neural networks have exhibited enhanced computational complexity when operated at the edge of chaos, and networks of chaotic elements have been proposed for solving combinatorial or global optimization problems. Thus, a source of controllable chaotic behaviour that can be incorporated into a neural-inspired circuit may be an essential component of future computational systems. Such chaotic elements have been simulated using elaborate transistor circuits that simulate known equations of chaos, but an experimental realization of chaotic dynamics from a single scalable electronic device has been lacking. Here we describe niobium dioxide (NbO2) Mott memristors each less than 100 nanometres across that exhibit both a nonlinear-transport-driven current-controlled negative differential resistance and a Mott-transition-driven temperature-controlled negative differential resistance. Mott materials have a temperature-dependent metal-insulator transition that acts as an electronic switch, which introduces a history-dependent resistance into the device. We incorporate these memristors into a relaxation oscillator and observe a tunable range of periodic and chaotic self-oscillations. We show that the nonlinear current transport coupled with thermal fluctuations at the nanoscale generates chaotic oscillations. Such memristors could be useful in certain types of neural-inspired computation by introducing a pseudo-random signal that prevents global synchronization and could also assist in finding a global minimum during a constrained search. We specifically demonstrate that incorporating such
Self-Oscillating 150 W Switch-Mode Amplifier Equipped with eGaN-FETs
DEFF Research Database (Denmark)
Duraij, Martijn; Iversen, Niels Elkjær; Petersen, Lars Press
2015-01-01
This paper discusses the effect of flux modulation in the electrodynamic loudspeaker with main focus on the effect on the force factor. A measurement setup to measure the AC flux modulation with static voice coil is explained and the measurements shows good consistency with FEA simulations. Measu...
DEFF Research Database (Denmark)
Pedersen, Jeppe Arnsdorf; Madsen, Mickey Pierre; Mønster, Jakob Døllner
2016-01-01
This paper describes a Very High Frequency (VHF) converter made with three Class-E inverters and a single ClassDE rectifier. The converter is designed for the US mains (120 V, 60 Hz) and can deliver 9 W to a 60 V LED. The converter has a switching frequency of 37 MHz and achieves an efficiency...
EMC Investigation of a Very High Frequency Self-oscillating Resonant Power Converter
DEFF Research Database (Denmark)
Pedersen, Jeppe Arnsdorf; Knott, Arnold; Andersen, Michael A. E.
2016-01-01
This paper focuses on the electromagnetic compatibility (EMC) performance of a Very High Frequency (VHF) converter and how to lower the emissions. To test the EMC performance a VHF converter is implemented with a Class-E inverter and a Class-DE rectifier. The converter is designed to deliver 3 W...... to a 60 V LED, it has a switching frequency of 37 MHz and achieves an efficiency of 80%. For an LED driver to be used on the consumer market it has to fulfil the standard regarding EMC emissions. The conducted emission is often used as a reason to increase the switching frequency to the VHF range to avoid...... the regulations. This converter shows to be well below the levels for conducted emission even without filtering. For the radiated emissions the converter is above the limits without input and output filters. Several designs with different ways to lower the emissions are implemented and the different layouts...
DEFF Research Database (Denmark)
Nielsen, Dennis; Knott, Arnold; Pfaffinger, Gerhard
2009-01-01
for its variation. Knowledge of switching frequency variations is of great importance with respect to electromagnetic interference (EMI). This paper will investigate, whether the switching frequency is depended on modulation index and audio reference frequency. Validation is done using simulations......, and the results are compared with measurements performed on a 50 W prototype amplifier. The switching frequency is tracked through accurate spectrum measurements, and very good compliance with simulation results are observed....
Two-frequency self-oscillations in a FitzHugh-Nagumo neural network
Glyzin, S. D.; Kolesov, A. Yu.; Rozov, N. Kh.
2017-01-01
A new mathematical model of a one-dimensional array of FitzHugh-Nagumo neurons with resistive-inductive coupling between neighboring elements is proposed. The model relies on a chain of diffusively coupled three-dimensional systems of ordinary differential equations. It is shown that any finite number of coexisting stable invariant two-dimensional tori can be obtained in this chain by suitably increasing the number of its elements.
Proskurin, S G; Avsievich, T I
2014-01-01
In this study the experimental dependencies of the velocity of shuttle endoplasmic motion in the isolated plasmodial strand of Physarum polycephalum obtained by laser Doppler microscopy are presented. The spectral analysis of the time dependencies of the endoplasm allows obtaining two distinct harmonic components. Influence of KCN and SHAM--inhibitors of cellular respiration--leads to a complete cessation of endoplasmic motion in the strand. After removal of the inhibitors the respiratory system becomes normal, gradually restoring the activity of both harmonic oscillation sources. Based on the spectral analysis the simulated time-dependent velocity of the endoplasmic motion is rather good consistent with experimental data.
Self-oscillating Ultrasonic Micro-motor and It’s Application
2003-06-01
development. 2. Principle and basic construction 2.1 Principle The ultrasonic motors use vibration of an elastic body, therefore there are many different...References 1. T.Takano, Y.Tomikawa and C.Kusakabe, “Same Phase Drive-Type Ultrasonic Motors Using Two Degenerate Bending Vibration Modes of a Disk”, IEEE... Ultrasonic Motors ”, OXFORD SCIENCE PUBRICATIONS (1993) 4. T.Satoh, “Vibration Alarm Analog Quartz Watch with Ultrasonic Micro-motor”, Journal of the
Two-Phase Interleaved Buck Converter with a new Digital Self-Oscillating Modulkator
DEFF Research Database (Denmark)
Jakobsen, Lars Tønnes; Andersen, Michael Andreas E.
2007-01-01
for traditional digital PWM modulators given a certain switching frequency. A synchronised version of the DiSOM modulator is derived for interleaved converters. A prototype interleaved Buck converter for Point of Load applications has been designed and built to test the performance of DiSOM modulator. The Di...
A Self-Oscillating Control Scheme for a Boost Converter Providing a Controlled Output Current
DEFF Research Database (Denmark)
Knott, Arnold; Pfaffinger, Gerhard R.; Andersen, Michael A. E.
2011-01-01
Most switched mode power supplies provide a regulated voltage at their output. However, there are applications requiring a controlled current. Among others are battery chargers, test equipment for converters driven by solar cells, and LED drivers. This paper describes a dc–dc power converter real...
Self-Oscillating 150 W Switch-Mode Amplifier Equipped with eGaN-FETs
DEFF Research Database (Denmark)
Duraij, Martijn; Iversen, Niels Elkjær; Petersen, Lars Press;
2015-01-01
This paper discusses the effect of flux modulation in the electrodynamic loudspeaker with main focus on the effect on the force factor. A measurement setup to measure the AC flux modulation with static voice coil is explained and the measurements shows good consistency with FEA simulations...
About Landau–Hopf scenario in a system of coupled self-oscillators
Energy Technology Data Exchange (ETDEWEB)
Kuznetsov, Alexander P.; Kuznetsov, Sergey P.; Sataev, Igor R.; Turukina, Ludmila V., E-mail: lvtur@rambler.ru
2013-12-17
The conditions are discussed for which an ensemble of interacting oscillators may demonstrate the Landau–Hopf scenario of successive birth of multi-frequency quasi-periodic motions. A model is proposed that is a network of five globally coupled oscillators characterized by controlled degree of activation of individual oscillators. Illustrations are given for successive birth of tori of increasing dimension via quasi-periodic Hopf bifurcations.
Photothermal self-oscillation and laser cooling of graphene optomechanical systems.
Barton, Robert A; Storch, Isaac R; Adiga, Vivekananda P; Sakakibara, Reyu; Cipriany, Benjamin R; Ilic, B; Wang, Si Ping; Ong, Peijie; McEuen, Paul L; Parpia, Jeevak M; Craighead, Harold G
2012-09-12
By virtue of their low mass and stiffness, atomically thin mechanical resonators are attractive candidates for use in optomechanics. Here, we demonstrate photothermal back-action in a graphene mechanical resonator comprising one end of a Fabry-Perot cavity. As a demonstration of the utility of this effect, we show that a continuous wave laser can be used to cool a graphene vibrational mode or to power a graphene-based tunable frequency oscillator. Owing to graphene's high thermal conductivity and optical absorption, photothermal optomechanics is efficient in graphene and could ultimately enable laser cooling to the quantum ground state or applications such as photonic signal processing.
Prandtl, Ludwig
1953-01-01
Equilibrium of liquids and gases ; kinematics : dynamics of frictionless fluids ; motion of viscous fluids : turbulence : fluid resistance : practical applications ; flow with appreciable volume changes (dynamics of gases) ; miscellaneous topics.
Nonlinear dynamics new directions theoretical aspects
Ugalde, Edgardo
2015-01-01
This book, along with its companion volume, Nonlinear Dynamics New Directions: Models and Applications, covers topics ranging from fractal analysis to very specific applications of the theory of dynamical systems to biology. This first volume is devoted to fundamental aspects and includes a number of important new contributions as well as some review articles that emphasize new development prospects. The second volume contains mostly new applications of the theory of dynamical systems to both engineering and biology. The topics addressed in the two volumes include a rigorous treatment of fluctuations in dynamical systems, topics in fractal analysis, studies of the transient dynamics in biological networks, synchronization in lasers, and control of chaotic systems, among others. This book also: · Presents a rigorous treatment of fluctuations in dynamical systems and explores a range of topics in fractal analysis, among other fundamental topics · Features recent developments on...
Properties of High Volume Fly Ash Concrete Compensated by Metakaolin or Silica Fume
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
The compressive strength and dynamic modulus of high volume fly ash concrete with incorporation of either metakaolin or silica fume were investigated. The water to cementitious materials ratio was kept at 0.4 for all mixtures. The use of high volume fly ash in concrete greatly reduces the strength and dynamic modulus during the first 28 days. The decreased properties during the short term of high volume fly ash concrete is effectively compensated by the incorporation of metakaolin or silica fume. The DTA results confirmed that metakaolin or silica fume increase the amount of the hydration products. An empirical relationship between dynamic modulus and compressive strength of concrete has been obtained. This relation provides a nondestructive evaluation for estimating the strength of concrete by use of the dynamic modulus.
VOLUMNECT: measuring volumes with Kinect
Quintino Ferreira, Beatriz; Griné, Miguel; Gameiro, Duarte; Costeira, João. Paulo; Sousa Santos, Beatriz
2014-03-01
This article presents a solution to volume measurement object packing using 3D cameras (such as the Microsoft KinectTM). We target application scenarios, such as warehouses or distribution and logistics companies, where it is important to promptly compute package volumes, yet high accuracy is not pivotal. Our application auto- matically detects cuboid objects using the depth camera data and computes their volume and sorting it allowing space optimization. The proposed methodology applies to a point cloud simple computer vision and image processing methods, as connected components, morphological operations and Harris corner detector, producing encouraging results, namely an accuracy in volume measurement of 8mm. Aspects that can be further improved are identified; nevertheless, the current solution is already promising turning out to be cost effective for the envisaged scenarios.
Anadromous fish inventory: Summary volume
US Fish and Wildlife Service, Department of the Interior — Summary volume, with discussion, on anadromous fish inventories, species lists, histories of fisheries, habitat, key spawning and rearing areas, runs/escapements,...
Organ volume estimation using SPECT
Zaidi, H
1996-01-01
Knowledge of in vivo thyroid volume has both diagnostic and therapeutic importance and could lead to a more precise quantification of absolute activity contained in the thyroid gland. In order to improve single-photon emission computed tomography (SPECT) quantitation, attenuation correction was performed according to Chang's algorithm. The dual-window method was used for scatter subtraction. We used a Monte Carlo simulation of the SPECT system to accurately determine the scatter multiplier factor k. Volume estimation using SPECT was performed by summing up the volume elements (voxels) lying within the contour of the object, determined by a fixed threshold and the gray level histogram (GLH) method. Thyroid phantom and patient studies were performed and the influence of 1) fixed thresholding, 2) automatic thresholding, 3) attenuation, 4) scatter, and 5) reconstruction filter were investigated. This study shows that accurate volume estimation of the thyroid gland is feasible when accurate corrections are perform...
Christodoulou, Marios; De Lorenzo, Tommaso
2016-11-01
Black holes that have nearly evaporated are often thought of as small objects, due to their tiny exterior area. However, the horizon bounds large spacelike hypersurfaces. A compelling geometric perspective on the evolution of the interior geometry was recently shown to be provided by a generally covariant definition of the volume inside a black hole using maximal surfaces. In this article, we expand on previous results and show that finding the maximal surfaces in an arbitrary spherically symmetric spacetime is equivalent to a 1 +1 geodesic problem. We then study the effect of Hawking radiation on the volume by computing the volume of maximal surfaces inside the apparent horizon of an evaporating black hole as a function of time at infinity: while the area is shrinking, the volume of these surfaces grows monotonically with advanced time, up to when the horizon has reached Planckian dimensions. The physical relevance of these results for the information paradox and the remnant scenarios are discussed.
Volumetric measurement of tank volume
Walter, Richard T. (Inventor); Vanbuskirk, Paul D. (Inventor); Weber, William F. (Inventor); Froebel, Richard C. (Inventor)
1991-01-01
A method is disclosed for determining the volume of compressible gas in a system including incompressible substances in a zero-gravity environment consisting of measuring the change in pressure (delta P) for a known volume change rate (delta V/delta t) in the polytrophic region between isothermal and adiabatic conditions. The measurements are utilized in an idealized formula for determining the change in isothermal pressure (delta P sub iso) for the gas. From the isothermal pressure change (delta iso) the gas volume is obtained. The method is also applicable to determination of gas volume by utilizing work (W) in the compression process. In a passive system, the relationship of specific densities can be obtained.
Ultrasonographic Measures of Volume Responsiveness
2017-02-01
AFRL-SA-WP-SR-2017-0005 Ultrasonographic Measures of Volume Responsiveness Sarah B. Murthi, MD February 2017...use, or sell any patented invention that may relate to them. Qualified requestors may obtain copies of this report from the Defense Technical...TITLE AND SUBTITLE Ultrasonographic Measures of Volume Responsiveness 5a. CONTRACT NUMBER FA8650-13-2-6D10 5b. GRANT NUMBER 5c. PROGRAM
Volumes of Polytopes Without Triangulations
Enciso, Michael
2014-01-01
We introduce a new formalism for defining and computing the volumes of completely general polytopes in any dimension. The expressions that we obtain for these volumes are independent of any triangulation, and manifestly depend only on the vertices of the underlying polytope. As one application of this formalism, we obtain new expressions for tree-level, n-point NMHV amplitudes in N=4 Super Yang-Mills (SYM) theory.
Disorders of Erythrocyte Volume Homeostasis
Glogowska, Edyta; Gallagher, Patrick G.
2015-01-01
Inherited disorders of erythrocyte volume homeostasis are a heterogeneous group of rare disorders with phenotypes ranging from dehydrated to overhydrated erythrocytes. Clinical, laboratory, physiologic, and genetic heterogeneity characterize this group of disorders. A series of recent reports have provided novel insights into our understanding of the genetic bases underlying some of these disorders of red cell volume regulation. This report reviews this progress in understanding determinants ...
Direct Multifield Volume Ray Casting of Fiber Surfaces.
Wu, Kui; Knoll, Aaron; Isaac, Benjamin J; Carr, Hamish; Pascucci, Valerio
2017-01-01
Multifield data are common in visualization. However, reducing these data to comprehensible geometry is a challenging problem. Fiber surfaces, an analogy of isosurfaces to bivariate volume data, are a promising new mechanism for understanding multifield volumes. In this work, we explore direct ray casting of fiber surfaces from volume data without any explicit geometry extraction. We sample directly along rays in domain space, and perform geometric tests in range space where fibers are defined, using a signed distance field derived from the control polygons. Our method requires little preprocess, and enables real-time exploration of data, dynamic modification and pixel-exact rendering of fiber surfaces, and support for higher-order interpolation in domain space. We demonstrate this approach on several bivariate datasets, including analysis of multi-field combustion data.
Utilization of pressure-volume curves in the pediatric patient.
Bone, R C; Jantzen, D; Heithold, R
1978-04-01
Seven patients treated with continuous mechanical ventialtion were monitored with static and dynamic pressure-volume curves. Three patients developed no pulmonary complications, and mechanical ventilation was discontinued within 96 hr. In four patients, pressure-volume curves were used as a diagnostic aid in the detection of the physiologic defect resulting from bronchoconstriction, atelectasis, loculated pleural fluid, pulmonary edema, and mucous plugging. These measurements were also utilized to evaluate the effectivess of therapeutic modalities such as treatment of bronchoconstriction with bronchodilators, mucous plugging with adequate suctioning, and drainage of loculated pleural effusion. Pressure-v-lume measurements are simple, noninvasive, and require the smae equipment used in continuous mechanical ventilation. Pressure-volume monitoring of pediatric patients with curves warrants further investigation to evaluate its value.
Bistability: requirements on cell-volume, protein diffusion, and thermodynamics.
Directory of Open Access Journals (Sweden)
Robert G Endres
Full Text Available Bistability is considered wide-spread among bacteria and eukaryotic cells, useful, e.g., for enzyme induction, bet hedging, and epigenetic switching. However, this phenomenon has mostly been described with deterministic dynamic or well-mixed stochastic models. Here, we map known biological bistable systems onto the well-characterized biochemical Schlögl model, using analytical calculations and stochastic spatiotemporal simulations. In addition to network architecture and strong thermodynamic driving away from equilibrium, we show that bistability requires fine-tuning towards small cell volumes (or compartments and fast protein diffusion (well mixing. Bistability is thus fragile and hence may be restricted to small bacteria and eukaryotic nuclei, with switching triggered by volume changes during the cell cycle. For large volumes, single cells generally loose their ability for bistable switching and instead undergo a first-order phase transition.
Heterogeneous Beliefs, Trading Volume, and Seemingly Emotional Stock Market Behavior
Institute of Scientific and Technical Information of China (English)
CHEN Zhanhui; YANG Xin
2007-01-01
Various information types and rational learning methods have shown that heterogeneous belief changes in a rational expectation model can explain many empirical findings in stock markets, such as momentum, contrarians, and technical trading. The methods have also shown that momentum and price movements can coexist in an asset market with only rational agents. The purpose of this paper is to provide a rational economic theory to explain these phenomena. Results of a dynamic programming model with heterogeneous beliefs show that the dynamic interactions between information diffusion and belief changes create continuation and reversals. The duration and magnitude of momentum and price movements are associated with trading volume. Therefore, rational investors should incorporate price and volume information in their trading decisions.
Quantum Gravity and the Nuts and Bolts of Thermodynamic Volumes
Johnson, Clifford V
2014-01-01
In theories of semi-classical quantum gravity where the cosmological constant is considered a thermodynamic variable, the gravitational mass of a black hole has been shown to correspond to the enthalpy of the thermodynamic system, rather than the energy. We propose that this should be extended to all spacetime solutions, and consider the meaning of this extension of gravitational thermodynamics for the Taub-NUT and Taub-Bolt geometries in four dimensional locally anti-de Sitter spacetime. We present formulae for their thermodynamic volumes. Surprisingly, Taub-NUT has negative volume, for which there is a natural dynamical explanation in terms of the process of formation of the spacetime. A special case corresponds to pure AdS_4 with an S^3 slicing. The same dynamical setting can explain the negative entropy known to exist for these solutions for a range of parameters.
The RESOLVE Survey: REsolved Spectroscopy Of a Local VolumE
Kannappan, Sheila; Norris, M. A.; Eckert, K. D.; Moffett, A. J.; Stark, D. V.; Haynes, M. P.; Giovanelli, R.; Berlind, A. A.; Wei, L. H.; Baker, A. J.; Vogel, S. N.; Hendel, D. A.; RESOLVE Team
2011-01-01
The RESOLVE Survey is a volume-limited census of stellar, gas, and dynamical mass as well as merging and star formation within 53,000 cubic Mpc of the nearby cosmic web in two long equatorial strips. The survey's primary science drivers include relating the galaxy velocity and mass functions to environment, constraining the "missing baryons" problem from a complete accounting perspective, and understanding galaxy disk building in large-scale context. RESOLVE's unique data product is high-resolution multiple-longslit spectroscopy, targeting all 1500 galaxies with baryonic (stellar + cold gas) mass > 109 Msun in the volume. Combined with a complete redshift survey, this spectroscopy will enable an unprecedented high dynamic-range view of how kinematically estimated mass is distributed on scales from dwarf galaxies to clusters. To trace stellar and gas mass, RESOLVE is drawing on deep public surveys at UV, optical, IR, and radio wavelengths, most notably the 21cm ALFALFA Survey. Here we present early results: (1) statistics of our efforts to recover galaxies missed by RESOLVE's parent survey, the SDSS; (2) calibration of indirect atomic and molecular gas estimators to supplement direct observations; (3) progress toward optimizing stellar mass and environment measures; and (4) a first installment of kinematic data focusing on S0 galaxies. This work is supported by the National Science Foundation under CAREER award 0955368.
Directory of Open Access Journals (Sweden)
Yusuke Hara
2013-09-01
Full Text Available This review introduces the self-oscillating behavior of two types of nonthermoresponsive polymer systems with Ru catalyst moieties for the Belousov-Zhabotinsky (BZ reaction: one with a poly-vinylpyrrolidone (PVP main chain, and the other with a poly(2-propenamide (polyacrylamide (PAM main chain. The amplitude of the VP-based self-oscillating polymer chain and the activation energy for self-oscillation are hardly affected by the initial concentrations of the BZ substrates. The influences of the initial concentrations of the BZ substrates and the temperature on the period of the swelling-deswelling self-oscillation are examined in detail. Logarithmic plots of the period against the initial concentration of one BZ substrate, when the concentrations of the other two BZ substrates are fixed, show good linear relationships. The period of the swelling-deswelling self-oscillation decreases with increasing temperature, in accordance with the Arrhenius equation. The maximum frequency (0.5 Hz of the poly(VP-co-Ru(bpy3 gel is 20 times that of the poly(NIPAAm-co-Ru(bpy3 gel. It is also demonstrated that the amplitude of the volume self-oscillation for the gel has a tradeoff with the self-oscillation period. In addition, this review reports the self-oscillating behavior of an AM-based self-oscillating polymer chain as compared to that of the VP-based polymer chain.
Dynamics of partial differential equations
Wayne, C Eugene
2015-01-01
This book contains two review articles on the dynamics of partial differential equations that deal with closely related topics but can be read independently. Wayne reviews recent results on the global dynamics of the two-dimensional Navier-Stokes equations. This system exhibits stable vortex solutions: the topic of Wayne's contribution is how solutions that start from arbitrary initial conditions evolve towards stable vortices. Weinstein considers the dynamics of localized states in nonlinear Schrodinger and Gross-Pitaevskii equations that describe many optical and quantum systems. In this contribution, Weinstein reviews recent bifurcations results of solitary waves, their linear and nonlinear stability properties, and results about radiation damping where waves lose energy through radiation. The articles, written independently, are combined into one volume to showcase the tools of dynamical systems theory at work in explaining qualitative phenomena associated with two classes of partial differential equ...
Institute of Scientific and Technical Information of China (English)
邬喆斌; 曹红; 刘婷; 吴泽倩; 柯伟民; 高志良
2012-01-01
Objective The aim of this study was to determine the dynamic expression profile of hepatitis B surface antigen (HBsAg) according to hepatic parenchyma cells' volume at different stages of liver fibrosis during the immune clearance phase.Methods Eighty-nine patients with HBeAg-positive chronic hepatitis B (CHB) in the immune clearance stage were recruited for study.Each patient's serum HBsAg levels were detected by electrochemiluminescence.The serum HBsAg levels were apportioned according to hepatic parenchyma cells' volume at liver fibrosis stages 1,2,3,and 4 and compared by ANOVA.Results The unapportioned serum HBsAg levels (IU/mL) at liver fibrosis stages 1 (227.2 ± 237.7),2 (211.0 ± 131.4),3 (300.1 ± 144.6),and 4 (278.7 ± 148.8) were not significantly different (all comparisons,P range:0.061～0.759).However,when the serum HBsAg levels were apportioned by the same hepatic parenchyma cells' volume at liver fibrosis stages 1 (343.9 ± 359.8),2 (336.4 ± 209.5),3 (508.7 ± 245.1),and 4 (525.2 ± 274.8),the levels were significantly different (all comparisons,F =3.045 and P =0.033; stage 1 vs.3,P =0.041;stage 1 vs.4,P =0.046; stage 2 vs.3,P =0.028; stage 2 vs.4,P =0.034).Conclusion During the immune clearance phase of chronic hepatitis B,increased HBsAg expression is associated with increased hepatic parenchyma cells' volume and progressive liver fibrosis stage.%目的 观察慢性乙型肝炎免疫清除期肝纤维化S1、S2、S3和S4期,相同肝实质细胞体积所分摊HBsAg表达的动态变化. 方法 对89例HBeAg阳性慢性乙型肝炎免疫清除期患者应用电化学发光法检测肝纤维化S1、S2、S3和S4期血清HBsAg的水平；进一步用相同肝实质细胞体积分摊并且两两比较肝纤维化S1、S2、S3和S4期血清HBsAg的水平.使用SPSS 15.0统计软件,组间用两两比较,采用ANOVA检验进行分析. 结果 肝纤维化S1、S2、S3和S4期的血清HBsAg水平分别为(227.2±237.7)IU/ml、(211.0±131.4)IU/ml、(300.2
Correlating the properties of amorphous silicon with its flexibility volume
Fan, Zhao; Ding, Jun; Li, Qing-Jie; Ma, Evan
2017-04-01
For metallic glasses, "flexibility volume" has recently been introduced as a property-revealing indicator of the structural state the glass is in. This parameter incorporates the atomic volume and the vibrational mean-square displacement, to combine both static structure and dynamics information. Flexibility volume was shown to quantitatively correlate with the properties of metallic glasses [J. Ding et al., Nat. Commun. 7, 13733 (2016), 10.1038/ncomms13733]. However, it remains to be examined if this parameter is useful for other types of glasses with bonding characteristics, atomic packing structures, as well as properties that are distinctly different from metallic glasses. In this paper, we tackle this issue through systematic molecular-dynamics simulations of amorphous silicon (a -Si) models produced with different cooling rates, as a -Si is a prototypical covalently bonded network glass whose structure and properties cannot be characterized using structural parameters such as free volume used for metallic and polymeric glasses. Specifically, we demonstrate a quantitative prediction of the shear modulus of a -Si from the flexibility for atomic motion. This flexibility volume descriptor, when evaluated on the atomic scale, is shown to also correlate well with local packing, as well as with the propensity for thermal relaxations and shear transformations, providing a metric to map out and explain the structural and mechanical heterogeneity in the amorphous material. This case study of a model of covalently bonded network a -Si, together with our earlier demonstration for metallic glasses, points to the universality of flexibility volume as an indicator of the structure state to link with properties, applicable across amorphous materials with different chemical bonding and atomic packing structures.
Volume analysis of supercooled water under high pressure
Duki, Solomon F.; Tsige, Mesfin
2016-01-01
Motivated by recent experimental findings on the volume of supercooled water at high pressure [O. Mishima, J. Chem. Phys. 133, 144503 (2010)] we performed atomistic molecular dynamics simulations study of bulk water in the isothermal-isobaric ensemble. Cooling and heating cycles at different isobars and isothermal compression at different temperatures are performed on the water sample with pressures that range from 0 to 1.0 GPa. The cooling simulations are done at temperatures that range from...
Energy Technology Data Exchange (ETDEWEB)
Ladd, A.J.C.
1988-08-01
The basic methodology of equilibrium molecular dynamics is described. Examples from the literature are used to illustrate how molecular dynamics has been used to resolve theoretical controversies, provide data to test theories, and occasionally to discover new phenomena. The emphasis is on the application of molecular dynamics to an understanding of the microscopic physics underlying the transport properties of simple fluids. 98 refs., 4 figs.
Second International Colloquium on Dynamical Systems
Seade, José; Verjovski, Alberto
1988-01-01
The objective of the meeting was to have together leading specialists in the field of Holomorphic Dynamical Systems in order to present their current reseach in the field. The scope was to cover iteration theory of holomorphic mappings (i.e. rational maps), holomorphic differential equations and foliations. Many of the conferences and articles included in the volume contain open problems of current interest. The volume contains only research articles.
Dynamics of mathematical models in biology bringing mathematics to life
Zazzu, Valeria; Guarracino, Mario
2016-01-01
This volume focuses on contributions from both the mathematics and life science community surrounding the concepts of time and dynamicity of nature, two significant elements which are often overlooked in modeling process to avoid exponential computations. The book is divided into three distinct parts: dynamics of genomes and genetic variation, dynamics of motifs, and dynamics of biological networks. Chapters included in dynamics of genomes and genetic variation analyze the molecular mechanisms and evolutionary processes that shape the structure and function of genomes and those that govern genome dynamics. The dynamics of motifs portion of the volume provides an overview of current methods for motif searching in DNA, RNA and proteins, a key process to discover emergent properties of cells, tissues, and organisms. The part devoted to the dynamics of biological networks covers networks aptly discusses networks in complex biological functions and activities that interpret processes in cells. Moreover, chapters i...
Federal Laboratory Consortium — The Dynamics Lab replicates vibration environments for every Navy platform. Testing performed includes: Flight Clearance, Component Improvement, Qualification, Life...
Sternberg, Shlomo
2010-01-01
Celebrated mathematician Shlomo Sternberg, a pioneer in the field of dynamical systems, created this modern one-semester introduction to the subject for his classes at Harvard University. Its wide-ranging treatment covers one-dimensional dynamics, differential equations, random walks, iterated function systems, symbolic dynamics, and Markov chains. Supplementary materials offer a variety of online components, including PowerPoint lecture slides for professors and MATLAB exercises.""Even though there are many dynamical systems books on the market, this book is bound to become a classic. The the
Multibody system dynamics, robotics and control
Gerstmayr, Johannes
2013-01-01
The volume contains 19 contributions by international experts in the field of multibody system dynamics, robotics and control. The book aims to bridge the gap between the modeling of mechanical systems by means of multibody dynamics formulations and robotics. In the classical approach, a multibody dynamics model contains a very high level of detail, however, the application of such models to robotics or control is usually limited. The papers aim to connect the different scientific communities in multibody dynamics, robotics and control. Main topics are flexible multibody systems, humanoid robots, elastic robots, nonlinear control, optimal path planning, and identification.
Dynamics and Thermodynamics of Nanoclusters
Directory of Open Access Journals (Sweden)
Karo Michaelian
2015-10-01
Full Text Available The dynamic and thermodynamic properties of nanoclusters are studied in two different environments: the canonical and microcanonical ensembles. A comparison is made to thermodynamic properties of the bulk. It is shown that consistent and reproducible results on nanoclusters can only be obtained in the canonical ensemble. Nanoclusters in the microcanonical ensemble are trapped systems, and inconsistencies will be found if thermodynamic formalism is applied. An analytical model is given for the energy dependence of the phase space volume of nanoclusters, which allows the prediction of both dynamical and thermodynamical properties.
Basic developments in fluid dynamics
Holt, Maurice
2012-01-01
Basic Developments in Fluid Dynamics, Volume 2 focuses on the developments, approaches, methodologies, reactions, and processes involved in fluid dynamics, including sea motion, wave interactions, and motion of spheres in a viscous fluid.The selection first offers information on inviscid cavity and wake flows and weak-interaction theory of ocean waves. Discussions focus on steady and unsteady cavity flows, radiation balance, theory of weak interactions in random fields, interactions between gravity waves and the atmosphere, and interactions within the ocean. The text then examines low Reynolds
Dynamical tunneling theory and experiment
Keshavamurthy, Srihari
2011-01-01
A prominent aspect of quantum theory, tunneling arises in a variety of contexts across several fields of study, including nuclear, atomic, molecular, and optical physics and has led to technologically relevant applications in mesoscopic science. Exploring mechanisms and consequences, Dynamical Tunneling: Theory and Experiment presents the work of international experts who discuss the considerable progress that has been achieved in this arena in the past two decades.Highlights in this volume include:A historical introduction and overview of dynamical tunneling, with case histories ranging from
Complex Dynamics in Communication Networks
Kocarev, Ljupco
2005-01-01
Computer and communication networks are among society's most important infrastructures. The internet, in particular, is a giant global network of networks without central control or administration. It is a paradigm of a complex system, where complexity may arise from different sources: topological structure, network evolution, connection and node diversity, or dynamical evolution. The present volume is the first book entirely devoted to the new and emerging field of nonlinear dynamics of TCP/IP networks. It addresses both scientists and engineers working in the general field of communication networks.
Insular volume reduction in schizophrenia.
Saze, Teruyasu; Hirao, Kazuyuki; Namiki, Chihiro; Fukuyama, Hidenao; Hayashi, Takuji; Murai, Toshiya
2007-12-01
Structural and functional abnormalities of the insular cortex have been reported in patients with schizophrenia. Most studies have shown that the insular volumes in schizophrenia patients are smaller than those of healthy people. As the insular cortex is functio-anatomically divided into anterior and posterior subdivisons, recent research is focused on uncovering a specific subdivisional abnormality of the insula in patients with schizophrenia. A recent ROI-based volumetric MRI study demonstrated specific left anterior insular volume reduction in chronic schizophrenia patients (Makris N, Goldstein J, Kennedy D, Hodge S, Caviness V, Faraone S, Tsuang M, Seidman L (2006) Decreased volume of left and total anterior insular lobule in schizophrenia. Schizophr Res 83:155-171). On the other hand, our VBM-based volumetric study revealed a reduction in right posterior insular volume (Yamada M, Hirao K, Namiki C, Hanakawa T, Fukuyama H, Hayashi T, Murai T (2007) Social cognition and frontal lobe pathology in schizophrenia: a voxel-based morphometric study. NeuroImage 35:292-298). In order to address these controversial results, ROI-based subdivisional volumetry was performed using the MRI images from the same population we analyzed in our previous VBM-study. The sample group comprised 20 schizophrenia patients and 20 matched healthy controls. Patients with schizophrenia showed a global reduction in insular gray matter volumes relative to healthy comparison subjects. In a simple comparison of the volumes of each subdivision between the groups, a statistically significant volume reduction in patients with schizophrenia was demonstrated only in the right posterior insula. This study suggests that insular abnormalities in schizophrenia would include anterior as well as posterior parts. Each subdivisional abnormality may impact on different aspects of the pathophysiology and psychopathology of schizophrenia; these relationships should be the focus of future research.
Molecular dynamics of a dense fluid of polydisperse hard spheres
Sear, Richard P.
2000-01-01
Slow dynamics in a fluid are studied in one of the most basic systems possible: polydisperse hard spheres. Monodisperse hard spheres cannot be studied as the slow down in dynamics as the density is increased is preempted by crystallisation. As the dynamics slow they become more heterogeneous, the spread in the distances traveled by different particles in the same time increases. However, the dynamics appears to be less heterogeneous than in hard-sphere-like colloids at the same volume fractio...
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.
Quantum dynamical semigroups and applications
Energy Technology Data Exchange (ETDEWEB)
Alicki, R. [Gdansk Univ. (Poland). Inst. of Theoretical Physics and Astrophysics; Lendi, K. [Zuerich Univ. (Switzerland). Inst. of Physical Chemistry
2007-07-01
Reinvigorated by advances and insights, in particular from the active fields of quantum information and computing, the quantum theory of irreversible processes has recently attracted growing attention. This volume introduces the very basic concepts of semigroup dynamics of open quantum systems and reviews a variety of modern applications. The present book, originally published as Vol. 286 (1987) in Lecture in Physics, has been newly typeset, revised and corrected and also expanded to include a review on recent developments. (orig.)
TAO/TRITON, RAMA, and PIRATA Buoys, Monthly, Dynamic Height
National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has monthly Dynamic Height data (a measure of the elevation of the sea level, calculated by integrating the specific volume anomaly of the sea water...
TAO/TRITON, RAMA, and PIRATA Buoys, Daily, Dynamic Height
National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has daily Dynamic Height data (a measure of the elevation of the sea level, calculated by integrating the specific volume anomaly of the sea water...
TAO/TRITON, RAMA, and PIRATA Buoys, Quarterly, Dynamic Height
National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has quarterly Dynamic Height data (a measure of the elevation of the sea level, calculated by integrating the specific volume anomaly of the sea water...
Averaged Lema\\^itre-Tolman-Bondi dynamics
Isidro, Eddy G Chirinos; Piattella, Oliver F; Zimdahl, Winfried
2016-01-01
We consider cosmological backreaction effects in Buchert's averaging formalism on the basis of an explicit solution of the Lema\\^itre-Tolman-Bondi (LTB) dynamics which is linear in the LTB curvature parameter and has an inhomogeneous bang time. The volume Hubble rate is found in terms of the volume scale factor which represents a derivation of the simplest phenomenological solution of Buchert's equations in which the fractional densities corresponding to average curvature and kinematic backreaction are explicitly determined by the parameters of the underlying LTB solution at the boundary of the averaging volume. This configuration represents an exactly solvable toy model but it does not adequately describe our "real" Universe.
Bergstra, J.A.; Bethke, I.
2002-01-01
Molecular dynamics is a model for the structure and meaning of object based programming systems. In molecular dynamics the memory state of a system is modeled as a fluid consisting of a collection of molecules. Each molecule is a collection of atoms with bindings between them. A computation is model
Blackburn, P.; Venema, Y.
2008-01-01
This paper examines various propositional logics in which the dynamic implication connective (discussed in Groenendijk and Stokhof's (1992) Dynamic Predicate Logic and Kamp's (1981) Discourse Representation Theory) plays the central role. Our approach is modal: the basic idea is to view as a binary
DEFF Research Database (Denmark)
Robe, Dominic M.; Boettcher, Stefan; Sibani, Paolo
2016-01-01
When quenched rapidly beyond their glass transition, colloidal suspensions fall out of equilibrium. The pace of their dynamics then slows down with the system age, i.e., with the time elapsed after the quench. This breaking of time translational invariance is associated with dynamical observables...
DEFF Research Database (Denmark)
Brorsen, Michael
These lecture notes are intended mainly for the 7th semester course "Fluid Dynamics" offered by the Study Committee on Civil Engineering, Aalborg University.......These lecture notes are intended mainly for the 7th semester course "Fluid Dynamics" offered by the Study Committee on Civil Engineering, Aalborg University....
Image plane sweep volume illumination.
Sundén, Erik; Ynnerman, Anders; Ropinski, Timo
2011-12-01
In recent years, many volumetric illumination models have been proposed, which have the potential to simulate advanced lighting effects and thus support improved image comprehension. Although volume ray-casting is widely accepted as the volume rendering technique which achieves the highest image quality, so far no volumetric illumination algorithm has been designed to be directly incorporated into the ray-casting process. In this paper we propose image plane sweep volume illumination (IPSVI), which allows the integration of advanced illumination effects into a GPU-based volume ray-caster by exploiting the plane sweep paradigm. Thus, we are able to reduce the problem complexity and achieve interactive frame rates, while supporting scattering as well as shadowing. Since all illumination computations are performed directly within a single rendering pass, IPSVI does not require any preprocessing nor does it need to store intermediate results within an illumination volume. It therefore has a significantly lower memory footprint than other techniques. This makes IPSVI directly applicable to large data sets. Furthermore, the integration into a GPU-based ray-caster allows for high image quality as well as improved rendering performance by exploiting early ray termination. This paper discusses the theory behind IPSVI, describes its implementation, demonstrates its visual results and provides performance measurements.
Control volume based hydrocephalus research
Cohen, Benjamin; Voorhees, Abram; Wei, Timothy
2008-11-01
Hydrocephalus is a disease involving excess amounts of cerebral spinal fluid (CSF) in the brain. Recent research has shown correlations to pulsatility of blood flow through the brain. However, the problem to date has presented as too complex for much more than statistical analysis and understanding. This talk will highlight progress on developing a fundamental control volume approach to studying hydrocephalus. The specific goals are to select physiologically control volume(s), develop conservation equations along with the experimental capabilities to accurately quantify terms in those equations. To this end, an in vitro phantom is used as a simplified model of the human brain. The phantom's design consists of a rigid container filled with a compressible gel. The gel has a hollow spherical cavity representing a ventricle and a cylindrical passage representing the aquaducts. A computer controlled piston pump supplies pulsatile volume fluctuations into and out of the flow phantom. MRI is used to measure fluid velocity, and volume change as functions of time. Independent pressure measurements and flow rate measurements are used to calibrate the MRI data. These data are used as a framework for future work with live patients.
Control volume based hydrocephalus research; a phantom study
Cohen, Benjamin; Voorhees, Abram; Madsen, Joseph; Wei, Timothy
2009-11-01
Hydrocephalus is a complex spectrum of neurophysiological disorders involving perturbation of the intracranial contents; primarily increased intraventricular cerebrospinal fluid (CSF) volume and intracranial pressure are observed. CSF dynamics are highly coupled to the cerebral blood flows and pressures as well as the mechanical properties of the brain. Hydrocephalus, as such, is a very complex biological problem. We propose integral control volume analysis as a method of tracking these important interactions using mass and momentum conservation principles. As a first step in applying this methodology in humans, an in vitro phantom is used as a simplified model of the intracranial space. The phantom's design consists of a rigid container filled with a compressible gel. Within the gel a hollow spherical cavity represents the ventricular system and a cylindrical passage represents the spinal canal. A computer controlled piston pump supplies sinusoidal volume fluctuations into and out of the flow phantom. MRI is used to measure fluid velocity and volume change as functions of time. Independent pressure measurements and momentum flow rate measurements are used to calibrate the MRI data. These data are used as a framework for future work with live patients and normal individuals. Flow and pressure measurements on the flow phantom will be presented through the control volume framework.
Impact of Trading Volume on Prediction of Stock Market Development
Directory of Open Access Journals (Sweden)
Rudolf Plachý
2014-01-01
Full Text Available The paper focuses on the influence of trading volume on quality of prediction of stock market development. The main objective of this article is to assess the influence of stock trading volume level on quality of prediction with use of technical analysis. The research was applied on stocks included in the S & P 500 index. Based on average daily trading volume, three aggregate indexes were constructed. The dynamics of index return volatility was modeled by GARCH-class models. GARCH(1,1, GJR and EGARCH models were estimated for each time series. The in-sample evidence indicated that the return volatility of the indexes can be characterized by significant persistence and asymmetric effects. The best estimate of each model was produced for the index of stocks with the highest average trading volume.However the result could differ based on the observed period, the volatility structure of the examined data supports the idea that influential investors respond to various shocks in the market primarily by closing or opening their largest position.The importance of the level of trading volume for the prediction of financial time series development was shown in the paper. This finding could help generate such volatility structure of time series which would allow to explain development of the time series by various models with better results.
Weisbuch, Gérard; Deffuant, Guillaume; Amblard, Frédéric
2005-08-01
We here discuss a model of continuous opinion dynamics in which agents adjust continuous opinions as a result of random binary encounters whenever their difference in opinion is below a given threshold. We concentrate on the version of the model in the presence of few extremists which might drive the dynamics to generalized extremism. A network version of the dynamics is presented here, and its results are compared to those previously obtained for the full-mixing case. The same dynamical regimes are observed, but in rather different parameter regions. We here show that the combination of meso-scale features resulting from the first interaction steps determines the asymptotic state of the dynamics.
Laird, Philip
1992-01-01
We distinguish static and dynamic optimization of programs: whereas static optimization modifies a program before runtime and is based only on its syntactical structure, dynamic optimization is based on the statistical properties of the input source and examples of program execution. Explanation-based generalization is a commonly used dynamic optimization method, but its effectiveness as a speedup-learning method is limited, in part because it fails to separate the learning process from the program transformation process. This paper describes a dynamic optimization technique called a learn-optimize cycle that first uses a learning element to uncover predictable patterns in the program execution and then uses an optimization algorithm to map these patterns into beneficial transformations. The technique has been used successfully for dynamic optimization of pure Prolog.